amq sr intro 3.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 33 (2), 2020, i-ii introduction to the special issue “historic and prehistoric landslides in the northern italian alps: implications for new hazard maps in mountainous areas”. sandro rossato 1, silvana martin 2, susan ivy-ochs 3, fabio gabrieli 4 � 1 institute of geosciences and earth resources, national research council of italy, padova, italy. 2 department of geosciences, university of padova, padova, italy. 3 department of earth sciences, eth zürich, zürich, and laboratory of ion beam physics, eth hönggerberg, zürich, schwitzerland. 4 department of civil, environmental and architectural engineering, university of padova, padova, italy people living and working in mountainous areas are familiar with landslides. these events are sadly known to pose a serious threat to people and infrastructures, being also a relevant process in landscape evolution. in the alps, where narrow valleys are increasingly inhabited, landslides occur every year, and some of them are responsible for a tragic number of casualties, and huge economic losses. in the last decades, a growing interest in such phenomena has developed, these phenomena being increasingly studied in all of their aspects. notwithstanding the uniformity of a goal to understand past failures as keys for assessing future events, the study of landslides has been dominated by an engineering geology approach, aimed at immediate risk reduction. in many cases, less attention has been paid to geomorphology, sedimentology, and dating. the landforms, sedimentology and internal structures of a landslide deposit provide direct information on the processes occurring during emplacement. back calculations and modelling of former rock-slope failures, when combined with the above, allow insight into movement processes photo of the participants to the summer school taken in the vajont valley, during fieldwork (photo: silvana martin, 4th july 2019). ii rossato s. et al. and emplacement sequences. reconstructing release and emplacement of mass movements provide fundamental data on the reasons for past and consequently possible future failure and extent of impacted areas. to evaluate which type of trigger (seismic, climatological, combined, man-made, ...) or driving factor played a role in slope failure is a major challenge, but there is a growing amount of data on this topic. landslides have been studied also as phenomena occurring on a certain area or time frame, moving the focus from the single event to a wider approach. clustering of some major rock slope failures in space and time have been recognized, pointing to triggers acting on vast areas. this volume collects contributions inspired by the summer school on “historic and prehistoric landslides in the ne italian alps implications for new hazard maps in mountainous areas”. this advanced course was organized by the university of padova (department of geosciences: prof. silvana martin and dr. sandro rossato; department of civil, architectural and environmental engineering: prof. fabio gabrieli) and eth zürich (prof. susan ivy-ochs). it was devoted to both early-career and experienced researchers dealing with landslide studies in the view of land management, risk reduction, and mapping. the summer school was held in 2019 at the university of padova, with teaching experts coming from many different countries. during the course, students and researchers, mainly, but not exclusively, european, had the opportunity to present and discuss their own work. more than half of the course consisted of fieldwork in the veneto and trentino/south tyrol regions. the course dealt with every aspect of landslide study: deposit investigation, failure and emplacement reconstruction, risk evaluation and monitoring in presently active sites. this volume reflects the multidisciplinary nature of the summer school that inspired it. wolter (2020) and viganò and scafidi (2020) focused respectively on predisposing and triggering factors, highlighting the importance of accurate structural and geophysical data in the landslide and, more in general, geologic studies. the investigations of three different events are also included: the pragser wildsee rock avalanche (ostermann et al., 2020), the mount salta rock-block sliderock fall (ghirotti et al., 2020), and the buchwiese rock avalanche (reitner et al., 2020). in the end, two review papers are presented, inspired by the summer school fieldwork in the veneto region (rossato et al., 2020) and the trentino/south tyrol area (martin et al., 2020). the special issue associate editors would like to take the opportunity to thank all the authors, the reviewers, and the editorial board of amq, whose individual contributions were fundamental. a special thank you is devoted also to the institutions that made the summer school possible thanks to their expertise and/or funding: the university of padova (departments of geosciences and civil, architectural and environmental engineering), the university of trento, the professional orders of the geologists of the trentino-alto adige region, the professional orders of the engineer of the veneto region, the geological survey of the autonomous provinces of trento and bolzano (italy), the eth zürich (switzerland), the geological survey of austria, the swiss society for quaternary research (ch-quat), the italian association for quaternary research (aiqua), the unesco dolomites foundation, and the sirive, incofil tech and unirock companies. � summer school historic and prehistoric landslides in the northern italian alps: implications for new hazard maps in mountainous areas list of the participants � � dr. jordan aaron eth zürich (ch); dr. raniero beber strathclyde university (uk); msc francesco bovo padova university (it); dr. paolo campedel geological survey, province of trento (it); prof. luca carniello padova university (it); msc ryan dick newcastle university (uk); msc davide festa bologna university (it); prof. fabio gabrieli padova university (it); dr. xavi gallach université savoie mont blanc (fr); prof. monica ghirotti ferrara university (it); msc gerit e.u. griesmeier geological survey of austria (at); dr. vladislav ivanov politecnico milano (it); prof. susan ivy-ochs eth zürich (ch); msc kacper jancewicz wroc�aw university (pl); msc sibylle knapp munich technical university (de); msc wioleta kotwicka wroc�aw university (pl); prof. franz livio insubria university (it); dr. volkmar mair geological survey, bolzano province (it); prof. silvana martin padova university (it); dr. costanza morino cnrs, université savoie montblanc (fr); prof. paolo mozzi padova university (it); prof. ryoko nishii niigata university (jp); dr. marc ostermann geological survey of austria (at); dr. alessandro pasuto irpi cnr, padova (it); dr. jürgen reitner geological survey of austria (at); prof. riccardo rigon trento university (it); prof. giorgio rosatti trento university (it); dr. sandro rossato padova university (it); prof. lorenzo sanavia university padova (it); msc carolina seguí duke university (usa); prof. nicola surian padova university (it); dr. hui tang german research centre for geosciences (de); dr. alfio viganò geological survey, province of trento (it); dr. andrea wolter gns science (nz); dr. jo wood exeter university (uk); prof. dario zampieri padova university (it); msc francesco zarattini padova university (it). available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 27 30 experimental determination of the friction coefficient for estimating sea storm induced megaboulders movements maurilio milella 1 , giovanni scardino 2 , arcangelo piscitelli 1 , francesco de giosa 1 , giuseppe locuratolo 1 , giovanni barracane 1 1 environmental surveys s.r.l. spin off università degli studi di bari “aldo moro”, taranto, italy 2 dipartimento di scienze della terra e geoambientali, università degli studi di bari “aldo moro”, bari, italy corresponding author: m. milella <maurisismo@libero.it> abstract: the presence of numerous boulders on rocky coast is linked to phenomena of detachment and deposit due to the occurrence of sea storms. currently, several hydrodynamic equations are known in the bibliography to estimate the wave height able to displace them, applying geometric parameters and hydrodynamic coefficients. a new methodological approach intends to consider the minimum energy required for the linear movement of a boulder along a weakly sloping rocky surface as a function of the friction coefficient. keywords: boulders, waves, friction coefficient 1. introduction along the rocky coast of the puglia region it’s evident the presence of geomorphological evidences represented by boulders deposits of various size whose origin has been connected to the occurrence of exceptional waves impact, due to tsunami and/or sea storms (cf. mastronuzzi and pignatelli 2012; pignatelli et al., 2009) (fig. 1). a new study has been carried out on the position and movement of these boulders using a new methodological approach, which consider the displacement of boulders by “many waves” impacting on rocky coast. this new approach requires the knowledge of the dynamic parameters of the rocky surface on which the detachment and displacement process occurs. this study, with respect to the equations known in the bibliography, focuses the attention on the energetic aspects of the storm rather than on the geometric parameter of a single wave. 2. material and methods the preliminary part of a more geographically extended study, has been conducted along a stretch of gently sloping rocky coast in san giovanni of polignano a mare, about 30 km se of the city of bari. in this location there are deposits of calcarenite blocks, from about 1 to 2,5 m 3 in size and 2 to 6 ton in weight, and located at different distances from the coast line, whose genesis has already been linked to the occurrence of exceptional fig. 1 boulders deposits in the studied area. https://doi.org/10.26382/aiqua.2018.aiquaconference waves, tsunami and/or storms, following previous studies (cf. mastronuzzi and sansò, 2004; 2000). the adopted methodological approach uses a “many waves” storm energy in place of the wave height, as a hydrodynamic parameter necessary to evaluate the way of moving these blocks. preliminarily, an lst survey was carried out to acquire the geometric characteristics of the rock surface and the shapes of some blocks so as to obtain indications on the general roughness of the contact surfaces and a three-dimensional reconstruction of the same blocks from which their volume can be obtained. the starting point for evaluating the storm waves energy is the following relation (cf. nandasena et al., 2011; noormets et al., 2004; nott, 2003; 1997) (fig. 2): this relationship implies the knowledge of these parameters: θ, slope of the rocky coastal surface; v and ρ, respectively, volume and density of the displaced rocky boulder; μ, the friction coefficient. θ and v were obtained directly from the lst survey and subsequent processing with specific solid modelling software. the parameter ρ is widely tabulated in the specific bibliography (cf. andriani and walsh, 2002). the estimate of the friction coefficient, on the other hand, was carried out using the following method: two boulders, a and b, with two different dimensions but a similar roughness of the contact surface, have been identified directly on rocky platform and chosen for the experimental proofs; then they have been subjected to some linear dragging along a rock surface by means of a mechanical apparatus; all the movement were recorded with a high resolution video camera positioned perpendicular to the direction of movement. the video analysis has allowed to obtain the displacement curve as a function of time (fig. 3), which allowed to obtain the value of the average acceleration necessary to calculate the friction coefficient (fig. 4). 3. results the graphs elaborations obtained through the analysis of the different videos were used to derive the accelerations “a” impressed to the different boulders by a physical apparatus to start and keep a linear displacement; then, these values were put in the inverse relation of the dynamics in order to calculate the friction coeffi 28 fig. 2 sketch of the force acting on a boulder. fig. 3 two different examples of video analysis software. milella m. et al. 29 cient, both static and dynamic, relative to the linear displacement of the considered boulders: the results of the values obtained for the static and dynamic friction coefficient are shown in tab.1. 4. discussion and conclusions the analysis of the results obtained from the graphic elaborations highlights the difference between the values of the static friction coefficient relative to the two sample boulders, a and b, where the “a” coefficient is lower than the “b” one. instead, the values of the dynamic friction coefficient relative to both boulders seem to be quite more similar. these results are certainly a first approach towards the determination of an experimental physical parameter whose value, for this type of lithology, wasn’t found in the reference bibliography. the determination of this coefficient is the first step to better estimate the energy to move a particular boulder on coastal surface and, then, to understand which sea storm can be responsible of this displacement. acknowledgement this work was carried out within the ph.d. project of the “programma operativo nazionale ricerca e innovazione 2014-2020 (cci 2014it16m2op005), fondo sociale europeo, azione i.1 “dottorati innovativi con caratterizzazione industriale”, università degli studi di bari “aldo moro”. references andriani g. f., walsh n. (2002) physical properties and textural parameters of calcarenitic rocks: qualitative evaluations. engineering geology, 67, 5-15. mastronuzzi g., pignatelli c. (2012) the boulder berm of punta saguerra (taranto, italy): a morphological imprint of the rossano calabro tsunami of april 24, 1836? earth planets space, 64, 1-14. mastronuzzi g., sansò p. (2004) large boulder accumulations by extreme waves along the adriatic coast of southern apulia (italy). quaternary international, 120, 173-184. mastronuzzi g., sansò p. (2000) boulders transport by catastrophic waves along the ionian coast of apulia (southern italy). marine geology, 170, 93103. nandasena n.a.k., paris r., tanaka n. (2011) reassessment of hydrodynamic equations: minimum flow velocity to initiate boulder transport by high energy events (storms, tsunamis). marine geolfig. 4 two different examples of speed/time graphic. tab. 1 friction coefficient values. “mi”: number of movement. experimental determination of the friction coefficient ogy, 281, 70-84. noormets r., crook k., felton e. (2004) sedimentology of rocky shorelines: hydrodynamics of megaclast emplacement and transport on a shore platform, oahu, hawaii. sedimentary geology, issue 172, 41-65. nott j. (1997) extremely high wave deposits inside the great barrier reef, australia; determining the cause tsunami or tropical cyclone. marine geology, 141, 193-207. nott j. (2003) waves, coastal boulders and the importance of the pre-transport setting. earth and planetary science letters, 210, 269-276. pignatelli c., sansò p., mastronuzzi g. (2009) evaluation of tsunami flooding using geomorphologic evidence. marine geology, 260, 6-18. 30 milella m. et al. ms. received: may 11, 2018 final text received: may 21, 2018 available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), i iii preface quaternary: past, presente, and future 40 years of italian quaternary in an alpine-mediterranean perspective adele bertini 1 , maria rita palombo 2 1 dipartimento di scienze della terra, università di firenze, firenze, italy 2 cnr-igag, area della ricerca di roma 1, c/o dipartimento di scienze della terra, università di roma “sapienza”, roma, italy the aim of the 2018 aiqua (italian association for quaternary studies) annual congress (earth science department, florence university, 13-15 june) was three -folded: i) to provide an overview on the status of quaternary research in italy, focusing on the new lines of research, in particular those performed by early-career researchers; ii) to discuss the most intriguing and multifaceted aspects related to quaternary studies, also in the perspective of correct public outreach and effective responses to societal challenges; iii) to celebrate the anniversary of four significant events, which fall in 2018. i) in 1928, international union for quaternary research inqua was nominally founded during a congress devoted to celebrate the founding (1888) of the danish geological institute (general international conference, copenhagen 17-30 june 1928). during the plenary session on the second day of the conference (26 june 1928) it was unanimously accepted the proposal presented by prof. m. limanowski (university of vilnius in lithuania) for the establishment and organisation of the “association for investigations of the quaternary of europe”. it taken some years before the european association became a world organisation (inqua), devoted to promoting quaternary researches and collaborations among scientists around the world, and reached its current structure (porter, 2003; smalley, 2011). ii) 70 years ago, during the 18th international geological congress held in london in 1948, it was agreed to place the pliocene-pleistocene boundary “... at the horizon of the first indication of climatic deterioration in the italian neogene succession” (king & oakley, 1949). the italian stratigraphers provided an outstanding contribution in defining the plio-pleistocene boundary, first formally defined in the stratotype section at vrica (calabria, southern italy) (aguirre and pasini, 1985) and successively lowered, after decades of discussion and following the recommendation of the 2008 international geological congress (igc), to the global stratotype section and point (gssp) of the gelasian stage/age at monte san nicola (sicily, italy) (gibbard et al., 2010), to encompass the time during which earth's climate has been strongly influenced by bi-polar glaciation, while the gssp at vrica remained available as the base of the calabrian stage/age. iii) 40 years ago (19 june 1978) the italian association for quaternary studies (aiqua) was founded, with the objective of gathering scholars working in the various fields of research dealing with the quaternary, promoting quaternary study and knowledge in italy and elsewhere, and enhancing the quaternary cultural and environmental heritage. iv) 30 years ago, on january 1st, 1988, the aiqua journal "il quaternario italian journal of quaternary science” (since 2012, “alpine and mediterranean quaternary”) started to be published. since that time hundreds of papers were published spanning nearly all the main quaternary issues and disciplines, from geomorphology, to archaeology, geodynamics, climatology, palaeontology, volcanology, palaeobotany, palaeoanthrolpology, ichnology, among others. https://doi.org/10.26382/aiqua.2018.aiquaconference since the beginning of the last century, besides its relevance for defining the plio-pleistocene boundary italy has been, indeed, a key territory for the study (sometimes pioneering) of the most recent events in the history of our planet, whose synergetic dynamics led to the modern geographical, climatic, and biogeographical setting, and italian researchers have been undisputed protagonists in various dedicated scientific disciplines, contributing to deconstruct the complex quaternary scenarios. the outstanding role of italy in quaternary studies is related to the variety and the complex history of its territory that has to be analysed and deconstructed in the context of the geodynamic, climatic, palaeobiogeographical and environmental evolution of the mediterranean basin, as well as of the alpine orogenesis and related phenomena. the mediterranean region, in fact, is geologically young and active and represents a hotspot of biodiversity and endemisms that characterise a region particularly suitable for discussing the dynamics interaction of processes and events that have shaped the physical and biotical scenarios succeeding each other in the last 2.6 millions of years. the scientific program of the 2018 aiqua annual congress included five sessions (coastal and marine processes, human and biosphere, palaeoclimate, stratigraphy and chronology, terrestrial processes), devoted to discuss the focal issues (e.g. climate change and its effects on ecosystems, main terrestrial processes in the short, medium and long term, rising sea level, volcanic and seismic activity, dynamics of plant and animal communities in a perspective of conservation of biodiversity and cultural heritage, dynamics of human population in the pleistocene and impact that human activity had on ecosystems during the most recent quaternary period in an alpine-mediterranean perspective. in particular, the session coordinated by m. anzidei and g. mastronuzzi was devoted to analyse and discuss the coastal and marine processes, especially focusing on the past relative sea level rising as the effect of climate change, but looking at expected scenarios for the coming decades. during the session, 8 oral communications have been presented that dealt with a number of different topics, such as issues possibly deriving from the extensive use of models in the face of a few new direct observations and data collection, methods and geodatabase related to palaeo-sea level markers, morphodynamics and landscape changes of coastal areas, as well as more punctual methodological approaches such as the determination of the friction coefficient for estimating sea storm. the session human and biosphere, coordinated by d. magri and m. peresani, included 13 oral presentations presented by palaeontologists, palaeoecologists, archaeologists, and geochemists, who introduced and examined, also in an interdisciplinary perspective and by means of advanced methodological approaches, a number of noteworthy and intriguing issues, such as the effects of climate changes on organisms, factors behind palaeoenvironment and ecosystems evolution, mainly focusing on terrestrial domain, and palaeolithic hominin behaviour and human impact on holocene environments (including pollution in the so called anthropocene recent and present time). the climate and palaeoclimate session, coordinated by f. lirer and f. toti, was devoted to present records and expected changes, processes and models, highlighting the results of research on all the aspects of quaternary climate, discussing the usefulness of proxies, presenting data syntheses, methods for inferring past climate, modelling and simulation of palaeoclimatic models. in line with the session aim, the 13 oral communications included in the session deal with different issues including case studied on palaeoclimate changes and climate instability and variability in marine and terrestrial domains, within and outside the mediterranean basin, studies on multiproxies environmental evolutionary dynamics and palaeoenvironmental evolution in different terrestrial contexts, and results obtained by means of quantitative methodological approaches and modelling. a fundamental basis for the reconstruction of quaternary events is provided by data coming from researches in the field of stratigraphy and chronology. the 8 contributions to the stratigraphy and chronology session, coordinated by m. balini and a. negri present classic and new methods of stratigraphical investigation, new data useful for an integration into a multidisciplinary stratigraphy, and critical evaluations of some principles of stratigraphic classification and correlation, and principles to be adopted in biostratigraphy and biochronology, as well as the criteria behind the database of terrestrial quaternary stratigraphical sites of europe currently under construction by an international teams of researchers working in the different quaternary disciplinary fields. the terrestrial processes session, coordinated by m. di vito, e. falcucci and p. mozzi, was planned to address the multiple and complex aspects and phenomena that regulate and constrain the history of continental environments, from tectonics to volcanoes, from extreme climatic events to earthquakes. following the session aim, the 13 oral communications addressed different themes even highlighting the role of quaternary research in the analysis of factors regulating environmental evolution and in the study and assessment of past, recent and present geological hazard. results presented by some contributions underlined the importance of multidisciplinary approaches to deconstruct complex quaternary geological events. the 2018 aiqua congress held in florence contributed to present the state-of-the-art and the diversity within the field of quaternary study, the most advanced researches on climate and landscape changes, marine and terrestrial processes, and ecosystems dynamics, highlighting the contribution of young researches in promoting the comparison and enhancing the analysis of the different quaternary evolutionary scenarios. deci ii bertini a., palombo m.r. iii phering the complex network of mechanisms leading to the present geological setting and biodiversity status is, likewise, of crucial relevance to understand the actual meaning of the processes acting today, and to plan appropriate actions for biodiversity conservation in view of the ongoing climate warming, correct public outreaches and effective responses to societal challenges, stretching our imagination beyond the present, and collects insights into the earth’s future scenario through a lesson from the past. references aguirre e., pasini g. (1985) the pliocene-pleistocene boundary. episodes, 8 (2), 116-120. gibbard p.l., head m.j., walker m.j., subcommission on quaternary stratigraphy (2010) formal ratification of the quaternary system/period and the pleistocene series/epoch with a base at 2.58 ma. journal of quaternary science, 25(2), 96-102. king w. b. r., oakley k. p. (1949) definition the pliocene-pleistocene boundary. nature, 163, 186187. porter s.c. (2003) inqua congresses: a 75th anniversary review. 16th (reno) inqua congress program with abstracts 8-9 (isbn 0-945920-512). available on line at www.inqua2003.dri.edu/ inqua03_program_p1-15.pdf smalley i. (2011) a history of inqua the international union for quaternary research. available on line at https://www.inqua.org/about/history beug h.j. (2015) leitfaden der pollenbestimmung für mitteleuropa und angrenzende gebiete. verlag dr. friedrich pfeil, munchen. preface: quaternary, past, present, future iv imp.laposta& le unità stratigrafiche di riferimento nella rappresentazione cartografica dei depositi plio-quaternari continentali nel progetto carg esempi relativi all'italia centro-meridionale elena la posta*, stefania nisio & felicia papasodaro apat servizio geologico d'italia/dipartimento difesa del suolo, roma, italy *corresponding author: e. la posta, apat servizio geologico d'italia/dipartimento difesa del suolo via curtatone, 3 -00185 roma, italy. e-mail: <elena.laposta@apat.it> abstract: e. la posta, s. nisio & f. papasodaro, reference stratigraphic units for plio-quaternary deposits mapping in carg. within the new geological map of italy at the 1:50.000 scale, unconformity bounded stratigraphic units have mostly been adopted, in the central-southern part of the country, to represent quaternary continental deposits. however, field geologists applied different criteria for their classification because of both the lack of prescriptions by stratigraphic codes and the absence of previous experience with such units in the italian setting. in some areas ubsu have been used as tools that allow us to synthesize: in a regional framework only a few units, bounded by disconformity related to important climatic events, have been identified. in other areas, due to the complex recent geological evolution and to poor correlation elements, ubsu have allowed only for local synthesis. parole chiave: unità stratigrafiche, ubsu, depositi del quaternario, carta geologica d'italia. keywords: stratigraphic units, ubsu (unconformity bounded stratigraphic units), quaternary deposits, geological map of italy. il quaternario italian journal of quaternary sciences 21(1a), 2008 57-60 premessa uno degli elementi innovativi nella nuova carta geologica d'italia, in corso di realizzazione attraverso il progetto carg, è l'interesse per lo studio e la rappresentazione dei depositi del quaternario. in assenza di unità formalizzate e di regole consolidate, il servizio geologico d'italia ha ritenuto, in seguito ad un lungo dibattito, che le unità stratigrafiche più adatte alla rappresentazione di questi depositi, oltre che riconosciute dai codici internazionali (issc, 1994), fossero le unità a limiti inconformi (cnr, 1992; cis, 2003). nell'individuazione di queste unità vengono presi in considerazione i cicli deposizionali, definiti attraverso l'identificazione di superfici di discontinuità che limitano depositi riferibili ad una stessa fase sedimentaria. queste superfici limite possono essere il prodotto sia di fasi erosive sia di lacune di sedimentazione, marcate spesso da paleosuoli, sia del concorso di entrambi i fenomeni. l'unità di base delle ubsu è il sintema, compreso gerarchicamente tra il supersintema, l'unità a rango più elevato limitata da una superficie di discontinuità di importanza ed estensione regionale, ed il subsintema, l'unità a rango meno elevato limitata da una superficie di discontinuità di carattere locale. la mancanza di una sperimentazione precedente di tali unità in ambito nazionale ha portato tuttavia ad un uso estremamente eterogeneo da parte dei gruppi di lavoro che stanno realizzando i fogli al 50.000, sia per quanto riguarda il numero di superfici di discontinuità prese in considerazione e la valenza ad esse attribuita, sia per quanto riguarda conseguentemente il numero di unità individuate ed il rango ad esse assegnato. a quasi vent'anni dall'inizio del progetto carg, nell'ambito dell'italia centro-meridionale sono in corso di realizzazione circa 150 fogli. partendo dall'analisi di quanto realizzato si possono trarre una serie di considerazioni sui differenti approcci seguiti e sulle problematiche più ricorrenti nella classificazione e rappresentazione dei depositi plio-quaternari. criteri ed esempi nell'italia centro-meridionale nonostante l'adozione delle ubsu sia ormai prevalente, in alcune regioni la rappresentazione del quaternario viene ancora portata avanti con un approccio tradizionale, ricorrendo sia alle unità litostratigrafiche, sia alle categorie senza formali connotazioni stratigrafiche previste dal dizionario delle unità quaternarie del servizio geologico d'italia (sgn, 1997; 2003), che fanno essenzialmente riferimento alla genesi dei depositi. questa impostazione caratterizza in particolare i progetti cartografici della regione toscana, della sicilia orientale, della calabria ed alcuni fogli della regione basilicata. a grandi linee nell'impostazione delle legende basate su unità a limiti inconformi si riconoscono due differenti approcci, l'uno con finalità di sintesi, l'altro con finalità più analitiche. nei progetti cartografici delle marche, dell'abruzzo ed in parte della sicilia occidentale le ubsu sono impiegate come strumento di sintesi. vengono 58 e. la posta et al. infatti individuate poche unità, valide per tutto il territorio regionale, delimitate da discontinuità legate ad importanti eventi climatici, per loro natura ubiquitari e quindi rintracciabili su aree estese. la correlazione di depositi e di superfici anche molto distanti fisicamente è comunque supportata da dati cronologici e talora favorita dalla presenza di livelli vulcanoclastici. nell'ambito dei diversi fogli può variare il grado di gerarchizzazione delle unità, come nel caso del supersintema di colle ulivo-colonia montani dei fogli delle marche, indifferenziato nel foglio urbino e suddiviso in sintemi ad esempio nel foglio jesi, e del supersintema aielli-pescina dei fogli dell'abruzzo, che raggruppa i depositi più antichi (pliocene?-pleistocene inferiore), indifferenziato nei fogli già stampati(1)* per la difficoltà di correlare a distanza affioramenti resi frammentari dalle dislocazioni tettoniche e dall'erosione fluviale e suddiviso in più sintemi in altri(2). tuttavia, nell'attuazione dei vari progetti cartografici, queste unità, seppur valide per ampie aree, spesso non superano i limiti regionali, come nel caso dei sopra citati fogli delle marche e dell'abruzzo nei quali unità assimilabili hanno diversa denominazione e talora diverso rango. il sintema di matelica dei fogli delle marche, ad esempio, sembra corrispondere al sintema di valle majelama dei fogli della regione abruzzo: entrambi racchiudono i depositi del pleistocene superiore e sono delimitati da superfici di erosione e paleosuoli correlati agli stessi eventi climatici. le conseguenze di tali scelte si manifestano con particolare evidenza nei fogli ubicati al confine tra regioni, dove l'adozione di più successioni di unità nell'ambito dello stesso foglio è talvolta giustificata da esigenze di coordinamento piuttosto che da motivazioni scientifiche(3). nella rappresentazione dei depositi più recenti, compresi tra il pleistocene superiore e l'olocene, in sicilia occidentale sono state considerate discontinuità riferibili ad importanti eventi climatici che hanno portato ad oscillazioni del livello del mare riconoscibili a scala regionale. sono state in tal modo definite tre unità sintemiche, comuni agli undici fogli del progetto(4). l'adozione di un approccio cartografico omogeneo, che utilizza le ubsu come strumento di sintesi regionale, si riscontra anche nei fogli che ricadono su estesi bacini di sedimentazione che hanno favorito la continuità dei corpi sedimentari. e' il caso del settore settentrionale del tavoliere delle puglie(5) dove è stata individuata una discontinuità di carattere regionale connessa all'importante fase erosiva verificatasi nel pleistocene inferiore, successivamente all'emersione della fossa bradanica. i successivi depositi marini ed alluvionali, che testimoniano il progressivo instaurarsi nell'area del dominio continentale, sono stati riuniti all'interno di un unico supersintema. al suo interno sono state individuate numerose unità di rango inferiore, soprattutto sintemi, separate da discontinuità di importanza minore. una situazione analoga è rappresentata dai fogli del litorale laziale(6) nei quali la discontinuità regionale del pleistocene inferiore, connessa con un periodo di stazionamento basso del livello del mare, è stata individuata come limite inferiore del supersintema aureliopontino. all'interno di questo vasto contenitore, comune ai diversi fogli, la complessa successione di depositi sedimentari e vulcanici, interessata da superfici di discontinuità di estensione minore, è stata riferita a più sintemi che differiscono nel settore settentrionale e nel settore meridionale. nel foglio ugento, ubicato al limite meridionale della regione puglia, attraverso una lettura dettagliata delle superfici di erosione che interessano una successione monotona di calcareniti, riferibili all'intervallo compreso tra il pleistocene medio ed il pleistocene superiore, sono stati distinti sei sintemi corrispondenti ad altrettanti cicli deposizionali. il legame tra le discontinuità e le variazioni eustatiche del livello del mare fa sì che, anche in questo caso, le unità siano caratterizzate da un'ampia estensione. * i numeri ad apice permettono di identificare i fogli presi in considerazione, citati in bibliografia. tab. 1 tipi di unità adottate e cartografate in aree caratterizzate dalla coesistenza di prodotti vulcanici e di depositi sedimentari. units defined and mapped where both volcanic products and sedimentary deposits crop out. unità adottate unità cartografate apparati unità unità prodotti depositi vulcanici sintemiche litostratigr. vulcanici sedimentari supersintemi sintemi subsintemi unita' unita' unita' unita' sintemiche litostratigr. sintemiche litostratigr. area laziale(6) x x x x x piana campana(8) x x x x x x vulture(9) x x x x x etna(10) x x x x in alcune regioni la presenza di contesti geologici a diversa evoluzione, la frammentarietà degli affioramenti dei depositi continentali quaternari e la carenza o mancanza di elementi di correlazione ha indotto all'adozione di una metodologia di tipo analitico che tiene conto della specificità di ciascun bacino o settore individuato nei fogli. ad esempio, nella regione campania sono state definite specifiche successioni di unità nei diversi settori individuati, corrispondenti a conche intermontane, bacini idrografici, piane costiere, ecc. nella legenda del foglio salerno, particolarmente complessa, sono state distinte 26 unità quaternarie formali, di tipo sintemico e litostratigrafico; queste ultime sono utilizzate ad integrazione delle unità a limiti inconformi per definire corpi geologici a litologia peculiare, come ad esempio i travertini. dalla correlazione delle unità individuate nei diversi contesti si desume che talvolta nello stesso intervallo cronologico è stato riconosciuto un diverso numero di cicli deposizionali ai quali è stato attribuito un differente rango gerarchico. la difficoltà di operare correlazioni tra bacini idrografici caratterizzati da un diverso numero di unità o tra settori litoranei a diversa evoluzione, porta talora ad individuare specifiche successioni corrispondenti ai diversi ordini di depositi alluvionali e marini terrazzati. ad esempio, in alcuni fogli della regione basilicata(7) sono stati definiti specifici supersintemi per ciascun bacino idrografico, anche di basso ordine gerarchico; i vari ordini sono stati rappresentati come sintemi. analogamente in sicilia occidentale(4) i depositi alluvionali e marini del pleistocene medio sono stati divisi in sintemi, riferibili ai diversi bacini e settori costieri; ai vari cicli deposizionali è stato attribuito il rango di subsintema. l'italia centro-meridionale è caratterizzata dalla presenza di importanti centri vulcanici attivi nel quaternario. in tali ambiti si osserva spesso l'integrazione di unità a limiti inconformi e di unità litostratigrafiche. nei fogli sono state per lo più definite unità sintemiche di vario rango, che raggruppano al loro interno sia i prodotti vulcanici sia i depositi sedimentari; in tal modo viene realizzata la correlazione tra ambienti sedimentari diversi. nella maggior parte dei casi, soprattutto per quel che riguarda i prodotti vulcanici, le unità sintemiche costituiscono dei contenitori di unità litostratigrafiche e non sono utilizzate nella rappresentazione cartografica (tab.1). conclusioni come si evince dalla sintetica rassegna presentata, nell'italia centro-meridionale per la cartografia dei depositi continentali quaternari vengono adottate prevalentemente le unità a limiti inconformi. tuttavia esse non sempre sono state utilizzate come strumento di sintesi; la complessa evoluzione geologica recente dell'italia centro-meridionale e la carenza di elementi utili di correlazione ha talvolta favorito la sintesi a scala locale. l'applicazione di questa metodologia, indubbiamente rigorosa, ha prodotto la redazione di legende molto articolate, caratterizzate da un gran numero di unità, e di carte di difficile lettura. tra i problemi più ricorrenti si può senz'altro citare l'applicazione di un criterio non omogeneo nella carat59le unità stratigrafiche di riferimento ... terizzazione delle superfici di discontinuità e nell'attribuzione del rango alle unità. bibliografia apat servizio geologico d'italia (2006) carta geologica d'italia alla scala 1:50.000 e relative note illustrative. fogli 359 l'aquila(1), 360 torre de' passeri( 1), 368 avezzano(1), 369 sulmona(1). apat servizio geologico d'italia (in allestimento per la stampa) carta geologica d'italia alla scala 1:50.000 e relative note illustrative. fogli 279 urbino, 292 jesi, 353 montalto di castro(6), 354 tarquinia(6), 407 s. bartolomeo in galdo(5), 448 ercolano (8), 451 melf i(9), 467 salerno (8), 607 corleone(4), 625 acireale(10). i fogli sono consultabili sul sito www.apat.it. apat servizio geologico d'italia (in corso di realizzazione) carta geologica d'italia alla scala 1:50.000 e relative note illustrative. fogli 344 tuscania(6), 355 ronciglione(6), 358 pescorocchiano(3), 374 roma(6), 378 scanno(2), 387 albano laziale(6), 396 san severo(5), 408 foggia(5), 421 ascoli satriano(5), 422 cerignola(5), 431 caserta est(8), 447 napoli(8), 452 rionero in vulture(9), 465 procida(8), 466 sorrento(8), 471 irsina(7), 536 ugento, 585 mondello(4), 593 castellammare del golfo(4), 594 partinico(4), 595 palermo(4), 596 capo plaja(4), 608 caccamo(4), 609 termini imerese(4). i fogli sono consultabili sul sito www.apat.it. ciscommissione italiana di stratigrafia (2003) guida italiana alla classificazione e alla terminologia stratigrafica. quaderni, serie iii, 9,155 pp. apat/dipartimento difesa del suolo. c.n.r.commissione per la cartografia geologica e geomorfologica (1992) carta geologica d'italia 1:50.000. guida al rilevamento. quaderni del servizio geologico nazionale, serie iii, 1, 203 pp. issc-international subcommission on stratigraphic classification (1994) international stratigraphic guide: a guide to stratigraphic classification, terminology and procedure. 2 nd edition.gsa, boulder. 214 pp. servizio geologico d'italia (1997) carta geologica d'italia 1:50.000. banca dati geologici. quaderni del servizio geologico nazionale, serie iii, 6,142 pp. servizio geologico d'italia (2001) indicazioni per il rilevamento del quaternario continentale. circolare carg disponibile sul sito web www.apat.it. servizio geologico d'italia (2003) indicazioni per la rappresentazione cartografica del quaternario continentale. circolare carg disponibile sul sito web www.apat.it. ms. ricevuto il 2 aprile 2008 testo definitivo ricevuto il 17 aprile 2008 ms. received: april 2, 2008 final text received: april 17, 2008 amq abs gattiglio et al tepro 213-216.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 213 216 multidisciplinary approach to reconstruct the geological quaternary evolution of the torrente traversola deformation zone (asti reliefs, nw italy) marco gattiglio, m. gabriella forno, mauro bonasera, cesare comina, alfredo doglione, franco gianotti, giandomenico fubelli dipartimento di scienze della terra, università di torino, torino, italy corresponding author: m.g. forno <gabriella.forno@unito.it> abstract: the results of geological and geophysical surveys performed in the asti reliefs along the torrente traversola deformation zone (ttdz), have been reported in this work. the outcropping “villafranchian ” succession shows local anomalies within this zone, consisting in sub-vertical geological contacts linked to faults, as well as bodies connected to gravitational reworking of sediments. this setting is due to the recent evolution of faults along the ttdz system, which is characterised by a main strike-slip movement. tectonic evolution has been clearly outlined by the combination of electric resistivity tomography and geological interpretation of the anomalies in the stratigraphic succession. keywords: “villafranchian” succession, asti reliefs, torrente traversola deformation zone, electric resistivity tomography, pliocene, quaternary 1. introduction research on the central piedmont hilly area (poirino plateau, asti reliefs and alessandria plateau) has been carried out in the last years, with the aim of reconstructing the stratigraphic pliocene and quaternary succession and its relations with the evolution of the main tectonic structures. in detail, the sediments outcropping in the asti reliefs belong to the “villafranchian” succession of the type-area comprising deltaic deposits (lower complex) and fluvial deposits (upper complex) (fig. 1a), which are separated by the cascina viarengo unconformity (carraro, 1996). the two complexes, resting on the shelf sandy deposits (asti sand of zanclean age), are referred to the piacenzian and calabrian respectively (dela pierre et al., 2003; forno et al., 2015). above the “villafranchian” sediments a widespread silty and locally gravelly fluvial cover of middle-upper pleistocene occurs, which is linked to po and tanaro rivers ancient courses. the whole sedimentary sequence is deformed by the asti syncline, which consists of a wide e-w regional -scale fold in the central hilly area (carraro et al., 1995) (fig. 1a). the transition between asti reliefs and poirino plateau corresponds to an evident regional scarp, that represents the morphological expression of the torrente traversola deformation zone (ttdz), as reported in the geological literature (carraro, 1996; gattiglio et al., 2015) (fig. 1a). this structure also dislocates the asti syncline axis that assumes a different location in the poirino plateau respect to the asti reliefs (fig. 1b). the ttdz belongs to the langhe seismic district, a region where no strong earthquake was recorded but a quite frequent microseismicity has been observed. about thirty earthquakes were recorded by ingv in the last decade between 1.0 to 4.1 ml. a multidisciplinary approach based on detailed field, geological, geomorphological and geophysical surveys were performed, to better define the ttdz significance and evaluate its seismic potential. 2. material and methods a detailed geological survey in the valmaggiore sector, developed along the ttdz fault system, was carried out (carraro, 1996; gattiglio et al., 2015) (fig. 1b). anomalies in the stratigraphic succession (soft sediment deformations and gravitational reworked bodies) as well as sub-vertical contacts, both probably connected to the evolutions of faults, were particularly investigated. a geomorphological analysis was also performed, regarding a possible connection between the river trend and the tectonic evolution of faults. an electric resistivity tomography (ert) was carried out along a survey line, where a sub-vertical geological contact has been identified, finalized to recognize and/or to confirm the presence of faults (fig. 2). the ert was executed by means of a syscal-pro tomograph (iris instruments) with 72 measuring electrodes at 2 m spacing. a wenner-schlumberger measuring sequence (with a total of 1247 measuring quadrupoles) was used in order to obtain a good compromise between both vertical and lateral resolution. acquired data were processed by the commercial inversion code res2dinv® (loke & barker, 1996). after preliminary data filtering a good convergence of the results has been obtained with rms error below 2 %. 3. results the most common sediments outcropping in the valmaggiore sector, texturally heterogeneous and very compact, are referred to the san martino unit https://doi.org/10.26382/aiqua.2018.aiquaconference (“villafranchian” lower complex) (fig. 2). they consist of predominantly planar bedded to massive clayey silt, that is typically grey, rich in scattered leaf and reed imprints, plant fragments, roots and pollen. the fine facies and fossils are usual in swamp environments where the mineral fraction and vegetal remains decanted in the water column. trough cross-bedded sand forms the fills of channel. the sandy texture, cross bedding and local vertebrate remains suggest a stream environment. the association of these two facies is typical of plain deltaic environment. specifically, the silt was deposited in coastal swamps, and the sand filled the deltaic distributary channels. the contact with the upper complex is marked by the cascina viarengo unconformity that represents the result of erosional phenomena that caused a progressive thickness reduction of the san martino unit towards the south. trough cross-bedded sediments with a component of minute gravel, referred to the cascina gherba unit (“villafranchian” upper complex), cover the previous unit. the gravelly-sandy texture and the absence of fossils suggest that they are associated to a fluvial channel environment. clayey silt forms the top of the “villafranchian” succession, referred to the maretto unit (“villafranchian” upper complex). it appears very weathered in its whole thickness (in consequence of several superimposed soils) and rich of carbonatic concretions. the silty-clayey texture and the strong weathering indicate that these sediments are associated to a continental fluvial plain in which the soils developed already during the sedimentation (forno et al., 2015). the sedimentary succession in the valmaggiore sector is dissected by many fractures striking from n350° to n10°, dipping towards the east and representing a fault system approximately characterised by n-s trend (fig. 3a). this system, only locally associated to soft sediment deformation, dislocates the whole sedimentary succession, involving both sediments of “villafranchian” lower and upper complexes. the geological evolution of this system occurred, therefore, in a long time spam, from a syn-sedimentary activity during the piacenzian to a post-sedimentary movement during the upper pleistocene. geological survey suggests that the western sector appears uplifted compared to the eastern one, evidencing an inverse component of movement. furthermore, the thickness of the san martino unit is greater in the eastern sector respect to the western one. the overall thickness change of these sediments (with values progressively increasing towards the north) suggests also a remarkable dextral strike-slip component for this fault. the geomorphological evidence also contributes to the tectonic reconstruction. the current watercourses essentially have n-s trend, different from their upper pleistocene configuration characterised, instead, by we main watercourses along the asti syncline axis. the current drainage network seems to be therefore driven by the n-s tectonic system, showing main stream flow (n-s) that superimposes a previous flow direction (w-e) (fig. 1b). a minor fault system showing n150° trend with an extensional component (lowering toward west) is also observed. it dislocates only part of “villafranchian” low complex, also creating small scarps se of case sossi. chaotic sediments, locally occurring in the lowered sector (asterisk in fig. 2), contain decimetric silty and sandy fragments characterised by various arrangement (fig. 214 fig. 1 a) simplified geological map of the piedmont hilly region with the location of the ttdz; b) aster global dem (nasa-miti, dec. 2009) showing the scarp between the poirino plateau and the asti reliefs. (1) asti syncline axis; (2) t. traversola deformation zone (ttdz); upper pleistocene ancient course of rivers: (3) tanaro, (4) po, (5) po and tanaro. the asterisk indicates the location of fig. 2 (from gattiglio et al., 2015). gattiglio m. et al 215 fig. 2 detailed geological map of the valmaggiore area, showing a n-s fault system referred to the ttdz. the asterisk indicates the reworked sediments of the san martino unit. fig. 3 a) n-s faults referred to the ttdz; b) chaotic sediments connected to reworking of the deltaic plain body (500 m south of case sossi). quaternary evolution of the torrente traversola deformation zone 3b). here trough cross-bedded sand connected to a filled channel also locally crops out, above the reworked body. the chaotic body is due to gravitational reworking phenomena of sediments as well as the location of the channel corresponds to the lowered sector. the n150° fault system is sealed by deltaic plain sediments (san martino unit), suggesting a syn-sedimentary tectonics. this geological reconstruction is also supported by the resulting resistivity distribution along the geophysical survey line (fig. 4). a marked sub-horizontal resistivity anomaly is observed along the e-w geophysical cross section in a surficial localized body approximately at progressive 52 m. this zone shows higher resistivity values (around 1000 ohm.m) with respect to the surrounding. this body is laterally interrupted by a subvertical band showing a minor resistivity anomaly approximately at progressive 36 m. the comparison between geological data (showing an isolated body formed by gravelly sand interrupted by a n-s fault system) and geophysical results suggests that these anomalies can be associated to cemented gravelly sand belonging to the cascina gherba unit, interrupted by a cemented sub-vertical band referred to the n-s fault system (fig. 4). the lower resistivity values observed (around 15 ohm.m) around this zone can be attributed to the silt of the san martino unit, with subordinate fine sand. the geophysical evidence supports therefore the geological reconstruction of a fault dislocating the stratigraphic continuity of sedimentary bodies. 4. discussion and conclusion the detailed geological survey allowed to observe that the stratigraphic succession is characterised by sub -vertical geological contacts as well sediments connected to gravitational reworking of the deltaic body. on the base of the geological and geomorphological evidences a fault of the ttdz has been detected around cascina volpiano. the comparison between geological and geophysical data also allows to confirm the presence and location of this fault. the electric resistivity tomography indicates the prosecution of the fault system in the shallow subsoil and the anomalous cementation of sediments along this system, already observed in other sectors. a strike-slip component of the n-s fault is evidenced by the thickness change of san martino unit, according to the main strike-slip evolution of the ttdz. this deformation zone also comprises n150° faults testifying syn-sedimentary tectonics. the tectonic evolution along the ttdz, dislocating both complexes of the “villafranchian” succession (referred to piacenzian and calabrian), took place in a long time interval and possibly is still active as suggested by the present microseismicity. references carraro f. (ed.) (1996) revisione del villafranchiano nell'area-tipo di villafranca d'asti. atti del convegno: "il significato del villafranchiano nella stratigrafia del plio-pleistocene" (peveragno (cn)villafranca d'asti (at), 20-24 giugno 1994). il quaternario, italian journal of quaternernary science, 9(1), 38-62. dela pierre f., piana f., fioraso g., boano p., bicchi e., forno m. g., violanti d., clari p., polino r., balestro g., d’atri a. (2003) foglio 157 “trino” della carta geologica d’italia alla scala 1: 50.000. apat, dipartimento difesa del suolo, roma. gattiglio m., forno m.g., comina c., doglione a., violanti d., barbero d. (2015) the involving of the pliocene-pleistocene succession in the t. traversola deformation zone (nw italy). alpine and mediterranean quaternary, 28(1), 59-70. forno m.g., gattiglio m., comina c., barbero d., bertini a., doglione a., irace a., gianotti f., martinetto e., mottura a., sala b. (2015) stratigraphic and tectonic notes on the villafranca d’asti type-area and castelnuovo don bosco sector (asti reliefs, piedmont). alpine and mediterranean quaternary, 28 (1), 5-27. loke m.h., barker r.d. (1996) rapid least-squares inversion of apparent resistivity pseudosections using a quasi-newton method. geophysical prospection, 44, 131-152. 216 fig. 4 resistivity distribution along the cascina volpiano geophysical survey line, with reported geological interpretation. gattiglio m. et al ms. received: may 9, 2018 final text received: may 23, 2018 sess 1_160211.pub il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 post-lgm valley fills from the northern coast of tuscany: depositional facies and stratigraphic architecture alessandro amorosi1, veronica rossi1, giovanni sarti2 & roberto mattei2 1 dipartimento di scienze della terra e geologico-ambientali, university of bologna, italy 2 dipartimento di scienze della terra, university of pisa, italy corresponding author: a. amorosi <alessandro.amorosi@unibo.it> abstract: amorosi a. et al., post-lgm valley fills from the northern coast of tuscany: depositional facies and stratigraphic architecture. (it issn 0349-3356, 2011) the stratigraphic architecture of three adjacent valley bodies of post-lgm age buried beneath the northern coast of tuscany is illustrated in detail. above a gravel fluvial deposit, the valley fills exhibit a distinctive succession of coastal plain to estuarine facies, punctuated by an aggradational stacking pattern of millennial-scale depositional cycles with distinctive climatic signature. radiocarbon dates document that the three valleys were active simultaneously and that rapidly created accommodation during transgression was filled under conditions of very high sediment supply. riassunto: amorosi a. et al., riempimenti vallivi tardoquaternari nel sottosuolo della piana costiera toscana: facies e architettura deposizionale. (it issn 0349-3356, 2011) il sottosuolo della costa toscana tra pisa e viareggio è caratterizzato da tre paleovalli, formatesi nel corso dell’ultimo ciclo glaciale-interglaciale. al di sopra di facies ghiaiose di canale fluviale, il riempimento delle paleovalli presenta un impilamento aggradazionale di parasequenze di piana costiera ed estuarine, formatesi in risposta a oscillazioni climatiche e del livello marino di durata circa millenaria. datazioni al radiocarbonio mostrano che le tre paleovalli furono attive contemporaneamente e che il loro riempimento avvenne durante la risalita del livello del mare in condizioni di elevato apporto sedimentario. key words: valley fill, sequence stratigraphy, parasequence, quaternary, tuscany parole chiave: riempimento di valle, stratigrafia sequenziale, parasequenza, quaternario, toscana 1. introduction the three-dimensional stratigraphic architecture of late quaternary valley fills has received increasing attention in the past decade, following the development of several sequence-stratigraphic models during the 1990s (van wagoner et al. 1990; dalrymple et al. 1994; zaitlin et al. 1994). however, given the difficulties in performing accurate geometric characterization of quaternary valley bodies on-land, where studies are mostly conducted on the basis of core analysis (gibling 2006), most examples of quaternary incised-valley fills stem primarily from offshore seismic investigations. after the early work by bellotti et al. (1994), milli (1997) and milli et al. (2008) on the tiber coastal plain, detailed facies documentation of late quaternary valley-fill sequences from the northern tyrrhenian coast has been recently provided by aguzzi et al. (2007) and amorosi et al. (2008; 2009) for the arno river system. this paper expands from previous work in the tuscan area, extending stratigraphic analysis of the post-last glacial maximum (post-lgm) succession to a 30 km-long transect, approximately parallel to the present tyrrhenian sea shoreline, from pisa to viareggio. this transect enables the comparison of the stratigraphic architecture beneath three adjacent river systems: arno, serchio and stiavacamaiore. 2. material and methods a dataset consisting of 2,600 stratigraphic data, with 40 continuously-cored reference boreholes, was used for this study. a wealth of information exists for the pisa area and the arno river. conversely, lower density stratigraphic data are available for serchio and camaiore-stiava river systems. in addition to the arno river (242 km long and with water discharge of about 110 m3/ sec), the study area includes serchio river (length: 111 km, discharge: 46 m3/sec) and camaiorestiava river basins. arno and serchio rivers are the main fluvial courses of northern tuscany, with catchment areas of 8228 km2 and 1400 km2, respectively. in contrast, camaiore river is just 19 km long, while stiava river is even shorter. facies characterization of the post-lgm succession also benefited from the analysis of the meiofauna (benthic foraminifers and ostracods) found within five reference cores (bergamin et al., 2006; amorosi et al., 2009). a total of twenty-five radiocarbon dates previously published in bergamin et al. (2006), mariotti lippi (2007) and amorosi et al. (2009) allowed to tie facies interpretation from cored wells into a sequence 8 10 9 stratigraphic framework. 3. post-lgm facies architecture stratigraphic correlation of core data collected along a cross-section transversal to the present fluvial-channel axes enables the identification of a suite of genetically related valley bodies that fill the incisions formed by arno, serchio and camaiorestiava rivers during the last glacial/interglacial cycle. valley bodies are 5 to 10 km wide and 30 to 45 m thick, with width/thickness ratios of about 100 -300. on the basis of facies analysis and palaeontologic characteristics, the valley fills can be subdivided into a series of millennial-scale depositional cycles (see amorosi et al. 2009). these cycles show that valley filling was associated with alternating freshwater and brackish conditions. individual small-scale cycles, about 10 m thick, are bounded by flooding surfaces (parasequences sensu van wagoner et al., 1990) and display similar facies architecture, with sharp-based central/outer estuarine clays grading upwards into inner-estuary and coastal-plain deposits. facies architecture within the valley bodies shows an aggradational, rather than retrogradational, stacking pattern of parasequences. diagnostic changes in vegetation patterns enable documentation of small-scale cycle development as a function of climate change (amorosi et al., 2009). particularly, pollen spectra show expansions of broad-leaved forests at parasequence boundaries, suggesting that rapid shifts to warmer climate conditions accompanied episodes of rapid sea-level rise. in contrast, stillstand phases saw the development of coldtemperate communities (upper parts of parasequences). the sedimentary response to these short-term phases of climatic cooling is documented by episodes of widespread coastalplain and bay-head delta progradation, which led to partial estuary infilling and temporary establishment of continental environments in the proximal and central sectors of the valleys. 4. sequence stratigraphy the post-lgm succession overlies alluvial deposits assigned to the last phase of base-level fall and subsequent lowstand. however, it can not be ruled out that part of the fluvial gravel bodies accumulated under early transgressive conditions. on the interfluves separating the major valley bodies the three deeply incised erosional surfaces (sequence boundary) pass into correlative subaerial exposure surfaces, characterized by indurated and weathered horizons associated with significant stratigraphic hiatuses. at these locations the sequence boundary merges with the transgressive erosional surface, marking the evolution of the incised-valley systems into wavedominated estuaries. the lower transgressive systems tract (tst), which accumulated between ca. 13,000 and 7,800 cal yr bp, records the progressive infilling and drowning of the tuscan paleovalleys in response to the rapid post-glacial sea-level rise. the three valley fills exhibit a composite succession of organic-rich muds formed in a coastal-plain or inner-estuarine environment, with upper transition to centraland outer-estuarine clays (lower tst). an aggradational stacking pattern of high-frequency depositional cycles within the valley fills suggests that sediment supply to the estuaries kept pace with increasing accommodation due to rapid sea-level rise in the early stages of transgression. the upper tst, which marks the change from an aggradational to a retrogradational depositional style, is characterized by a marked deepeningupward tendency (transition to thin nearshore and shallow-marine deposits) and by a typical erosional lower boundary (wave ravinement surface). the maximum flooding surface separates the tst from the overlying highstand systems tract (hst). its age is very well constrained in all valley fills around 7,800 years bp on the basis of radiocarbon dates. this almost isochronous surface, which represents the holocene peak of transgression in the study area, has no obvious physical expression, but can be easily identified from core samples containing the most marine-influenced microfossil assemblage. 5. conclusions few studies have dealt with synchronous valley incision and filling during the last glacial/interglacial cycle as deduced from borehole data. close examination of a valuable stratigraphic dataset beneath the tuscan coastal plain penetrating the post-lgm succession shows the presence of three coexisting incised-valley systems oriented roughly normal to the present shoreline. the application of sequence-stratigraphic analysis through the identification of significant stratigraphic surfaces enables the interpretation of depositional-facies origin and distribution of the post-lgm succession in the study area. above lowstand/early transgressive fluvial deposits, the three valley fills share a common depositional style, including a transgressive succession of innerto outer-estuary facies. where high-resolution core descriptions are available, including micropaleontological and pollen characterization, depositional cycles of lower rank (parasequences) can be delineated within the valley bodies. the vertical succession of facies suggests that the three valleys experienced a common depositional history. fluvial incision post-lgm valley fills from the northern coast of ... 10 occurred close to or during the lgm, while wavedominated estuaries developed into the valley systems during the ensuing post-lgm phase of sea-level rise. the three valley fills keep record of very high sedimentation rates (about 1 cm/year). sediment supply kept pace with sea-level rise during the early stages of transgression, leading to a distinctive aggradational (and even weakly progradational) facies architecture within the valley bodies. references aguzzi m., amorosi a., colalongo m.l., ricci lucchi m., rossi v., sarti g. & vaiani s.c. (2007) late quaternary climatic evolution of the arno coastal plain (western tuscany, italy) from subsurface data. sedimentary geology, 211, 211–229. amorosi a., sarti g., rossi v. & fontana v. (2008) anatomy and sequence stratigraphy of the late quaternary arno valley fill (tuscany, italy). in: a. amorosi, b.u. haq and l. sabato (eds.) advances in application of sequence stratigraphy in italy. geoacta special publication, 1, 55–66. amorosi a., ricci lucchi m., rossi v. & sarti g. (2009) climate change signature of small-scale parasequences from lateglacial-holocene transgressive deposits of the arno valley fill. palaeo3, 273, 142–152. bellotti p., chiocci f.l., milli s., tortora p. & valeri p. (1994) sequence stratigraphy and depositional setting of the tiber delta: integration of high-resolution seismics, well logs, and archaeological data. journal of sedimentary research, 64, 416–432. bergamin l., di bella l., frezza v., devoti s., nisi m.f., silenzi s., carboni m.g. (2006) late quaternary palaeoenvironmental evolution at the versilian coast (tuscany, italy). in: micropalaentological proxies: proceedings of the second and third italian meetings on environmental micropaleontology-grzybowski foundation special publications, 11, 1–11. dalrymple r.w., boyd r. & zaitlin b.a. (1994) history of research, types and internal organization of incised-valley systems: introduction to the volume. in: r.w. dalrymple r. boyd & b.a. zaitlin (eds.) incised-valley systems: origin and sedimentary sequences. sepm special publication, 51, 3–10. gibling m.r. (2006) width and thickness of fluvial channel bodies and valley fills in the geological record: a literature compilation and classification. journal of sedimentary research, 76, 731–770. mariotti lippi m., guido m., menozzi b.i., bellini c. & montanari c. (2007) the massaciuccoli holocene pollen sequence and the vegetation history of the coastal plains by the mar ligure (tuscany and liguria, italy). vegetation history and archaeobotany, 16, 267– 277. milli s. (1997) depositional setting and high-frequency sequence stratigraphy of the middle-upper pleistocene to holocene deposits of the roman basin. geologica romana, 33, 99-136. milli s., moscatelli m., palombo m.r., parlagreco l. & paciucci m. (2008) incised valleys, their filling and mammal fossil record: a case study from middle-upper pleistocene deposits of the roman basin (latium, italy). in: a. amorosi, b.u. haq and l. sabato (eds.) advances in application of sequence stratigraphy in italy. geoacta special publication, 1, 67-87. van wagoner j.c., mitchum r.m., campion k.m. & rahmanian v.d. (1990) siliciclastic sequence stratigraphy in well logs, cores and outcrops: concepts for high resolution correlations of time and facies. american association of american petroleum geologists, methods in exploration 7, tulsa, u.s.a. zaitlin b.a., dalrymple r.w., & boyd r. (1994) the stratigraphic organization of incised-valley systems associated with relative sea-level change. in: r.w. dalrymple, r. boyd and b.a. zaitlin (eds.) incisedvalley systems: origin and sedimentary sequences. sepm special publication, 51, 45–60. ms. received: january 15, 2011 testo ricevuto il 15 gennaio 2011 a. amorosi et al. available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternaryvol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 75 77 middle pleistocene human and animal mobility at isernia la pineta: a strontium and oxygen isotope perspective federico lugli 1,2 , anna cipriani 2,3 , julie arnaud 4 , marta arzarello 4 , giuseppe lembo 4 , renée janssen 5 , hubert vonhof 5 , carlo peretto 4 , stefano benazzi 1,6 1 department of cultural heritage, university of bologna, ravenna, italy 2 department of chemical and geological sciences, university of modena and reggio emilia, modena, italy 3 lamont-doherty earth observatory, columbia university, palisades, new york, usa 4 department of humanities, section of prehistorical and anthropological sciences, university of ferrara, ferrara, italy 5 department of climate geochemistry, max planck institute for chemistry, mainz, germany 6 department of human evolution, max planck institute for evolutionary anthropology, leipzig, germany corresponding author: f. lugli <federico.lugli6@unibo.it> abstract: in this work, we explored the isotopic composition of faunal (rodents, rhinoceros and bison) and human skeletal remains from the middle pleistocene layers of isernia la pineta (molise, italy). we particularly focused on high spatial resolution isotope analyses of tooth enamel by laser ablation mc-icp-ms for strontium isotopes and by micro-drilling sampling for oxygen isotopes. results from bone specimens were compared with the isotope variability of modern plants collected in the area surrounding the site, in a radius of about 30 km. while the human group seems local, macro-mammals show a higher degree of mobility. keywords: isotopes, middle pleistocene, deciduous tooth, strontium isotopes, laser ablation, oxygen isotopes 1. introduction in recent years, the use of isotope ratios (e.g. 87 sr/ 86 sr and δ 18 o) to decrypt past human and animal migratory patterns has been an important tool in archaeological and paleontological research. in particular, the discovery and significance of natural variations in the isotopic composition of strontium in biological and inorganic materials, has made sr isotopes one of the best geochemical indicators for provenance studies (bentley, 2006). as an alkaline earth metal with chemical-physical properties similar to those of calcium, strontium is commonly found in natural calcium carbonate (e.g. shells and speleothems) and phosphate (e.g. bones and teeth). the ratio between the isotopes 87 sr and 86 sr can be employed as a provenance marker typically deriving from a precise geological area depending on the age and on petrochemical features of the local rocks. thus, sr enters the ecosystem reaching plants and animals, mainly through water, following erosion and weathering of the bedrock. sr is mainly fixed in the hydroxyapatite of teeth and bone tissue substituting calcium, with concentrations ranging between c.a. 50 to 1000 ppm. in this sense, tooth enamel becomes the best target tissue to perform sr isotope analysis. this is because of two different reasons. first, being a ~96% mineralized tissue (mainly hydroxyapatite ca10(po4)6(oh)2), enamel is quite resistant to diagenetic alterations, usually preserving the biogenic isotopic signature of the individuals. second, enamel forms during childhood and does not remodel during the life of the individual, therefore, its sr isotopic composition should reflect the signature of the place where the individual has spent its youth. this makes teeth the perfect target to unravel human/animal migrations (lugli et al., 2017a). similarly, oxygen is fixed within carbonate and phosphate groups of the hydroxyapatite. the δ 18 o composition of tooth enamel reflects the isotope composition of the body water, which, in turn, varies linearly with the local meteoric water. consequently, the δ 18 o value of skeletal remains is an important tool the decrypt the palaeoclimatic proxies, but also to track possible movements of an individual between places with different environmental conditions (pellegrini et al., 2011). in this work, we used isotope techniques to explore the mobility patterns of humans and animals from the middle pleistocene layers of isernia la pineta (molise, italy; peretto et al., 2015). in particular, the most ancient human deciduous tooth ever found in italy (~580 ka) years was studied employing the micro-destructivity offered by the laser ablation mc-icp-ms. the mobility of the human was thus compared with macro-mammal (bison and rhinoceros) mobility patterns and with the local bioavailable sr isotope composition obtained from the analysis of modern plants grown in areas away from holocene contaminations and on and micro-mammals from the middle pleistocene layers of the site (i.e. rodents; lugli et al., 2017b). moreover, to get new insights https://doi.org/10.26382/aiqua.2018.aiquaconference into the stephanorhinus hundsheimensis migratory patterns and to unravel possible routes taken by this animal, we measured sr and oxygen isotopes of the outer enamel surface in a high spatially resolved approach. 2. material and methods the 87 sr/ 86 sr ratios of the is42 human and of a stephanorhinus hundsheimensis tooth were determined by la-mc-icp-ms technique. we sampled several portions (linear transects) of the external enamel surface, following a cervical-incisal direction (human enamel n = 5; rhino enamel n = 25). sr data were acquired with a double focusing mc-icp-ms neptune™ (thermo fisher scientific), coupled to a 213 nm nd:yag laser ablation system (new wave research™), housed at the centro interdipartimentale grandi strumenti (cigs) of the university of modena and reggio emilia. the detailed protocol is described in lugli et al. (2017a). in order to maximize the ion beam size stability, we chose to use dynamic linear ablation (500 x 100 µm), which provides more precise results compared to static spot ablation. we employed a laser frequency of 10 hz and an energy of ~20 j/cm 2 . the following masses were collected using nine faraday detectors: 88 sr, 87 sr, 86.5, 86 sr, 85 rb, 85.5, 84 sr, 83 kr, 82 kr. a 60 s background signal for each mass was collected before the analysis to correct for kr interferences. the presence of doubly-charged dy, yb and er was negligible, also suggesting a low content of rare earth elements within the enamel tissue. data were acquired in single blocks of 200 cycles, with an integration time of 0.5 s. to correct for the formation of 40 ca 13 p 16 o and 40 ar 13 p 16 o, we employed a set of inhouse bioapatite reference materials (a swine tooth, a bovine tooth and a shark tooth) building a calibration curve. the analysis of our human tooth in-house reference material (rocht42) yielded an average (n = 10) la 87 sr/ 86 sr ratio of 0.70865 ± 0.00040 (2σ) and an accuracy of 0.005% (16 ppm) compared with the true value obtained by dissolution mc-icp-ms of 0.70864 ± 0.00001 (2se). faunal enamel samples and modern plant specimens were analyzed after chemical dissolution and chromatographic separation of sr. samples preparation follows the protocol presented in lugli et al. (2017a). 510 mg of enamel and about 15 mg of plant ashes were digested in 1 ml of 14n hno3 and re-dissolved in 3n hno3 after evaporation. the sr separation uses columns with a ~300µl volume filled with eichrom sr specresin. sr isotope ratios were determined using the mcicp-ms neptune at the cigs unimore. a [blank/ standard/blank/sample/blank] bracketing sequence was adopted to monitor any instrumental drift. data were normalized through exponential law to a 88 sr/ 86 sr ratio of 8.375209. during this analytical session, the standard yielded a 87 sr/ 86 sr ratio of 0.71025 ± 0.00002 (2σ; n = 33). the sr ratios were corrected for instrumental bias to a nbs-987 value of 0.71026 ± 0.00002. high resolution (0.5 mm) sampling for stable isotope analysis was done on the outer enamel surface of a s. hundsheimensis tooth specimen (apex-cervix direction), using a micro-drilling system. fifty-eight samples were obtained this way. the δ 18 o isotope composition was thus determined at the max planck institute for chemistry (mainz, germany) on a thermo v mass spectrometer, equipped with a gasbench ii preparation device and a cold trap. in this configuration, tooth enamel samples of <100 microgram (equivalent of <5 microgram caco3) can be measured with <0.15‰ precision (1sd). 3. results the human tooth yielded an average 87 sr/ 86 sr ratio of 0.70914 ±0.00038 (2σ; 5 ablation lines). rodent teeth, analyzed by dissolution mc-icp-ms, showed an 80 lugli f. et al. fig. 1 (a) strontium isotope data from human, fauna and modern plant specimens of the isernia la pineta site and surroundings. (b) high spatial resolution analyses of strontium isotopes and oxygen isotopes of a single s. hundsheimensis tooth. 81 average sr isotope composition of 0.70924 ±0.00013 (2σ; n =16). seven bison teeth yielded 87 sr/ 86 sr ratios ranging between 0.70927 and 0.70954 (average 0.70938 ±0.00018; 2σ; n =7). rhinoceros teeth, measured by dissolution mc-icpms, showed an 87 sr/ 86 sr ratio ranging from 0.70941 and 0.70979 (average 0.70958 ±0.00030; 2σ; n =9). one rhinoceros tooth was also analyzed by la-mc-icp-ms to explore its intratooth variability, yielding 87 sr/ 86 sr ratios ranging between 0.71019 to 0.70956 (0.70982 ±0.00038; 2σ; n = 25). on the same tooth, high resolution oxygen isotope analyses yielded δ 18 oc (smov) values between 24.6 and 26.6‰. these values were then converted in δ 18 o phosphate values and in δ 18 o water values using regression from pellegrini et al (2011) and d’angela & longinelli (1990). 4. discussion and conclusion when compared with micro-mammals and local plants, the human sr isotope composition falls within the supposed local isotopic variability (fig. 1). this suggests that the human group from isernia likely exploited local resources, within a limited supply area (c.a. 10-15 km), similarly to modern hunter-gatherer collectors (lugli et al., 2017b). on the contrary, given that the sr isotope composition of macro-mammals seems affected by a higher radiogenic sr signature, we infer that both rhinos and bisons grazed on a different supply area. we suggest that the higher 87 sr/ 86 sr ratio derives from the contamination with volcanic soils and are likely related to seasonal migrations in the south-west direction, toward the fertile grounds of the roccamonfina volcano area (conticelli et al., 2009). the high-resolution isotope analysis of a s. hundsheimensis tooth agrees with this interpretation. in fact, both sr and o isotope ratios show clear fluctuations correlated with the growth of the tooth enamel within a period of ca. 400 days (fig. 1). these variations can be related to seasonal movements between places with different oxygen and sr isotope composition (e.g. from isernia to roccamonfina/albani hills and vice-versa). acknowledgements this project was funded by the european research council (erc) under the european union’s horizon 2020 research and innovation programme (grant agreement no 724046 success awarded to prof. stefano benazzi erc-success.eu). additional funding was provided through the programma giovani ricercatori rita levi montalcini (to ac). references bentley r.a. (2006) strontium isotopes from the earth to the archaeological skeleton: a review. journal of archaeological method and theory, 13, 135187. conticelli s., marchionni s., rosa d., giordano g., boari e., avanzinelli r. (2009) shoshonite and sub-alkaline magmas from an ultrapotassic volcano: sr-nd-pb isotope data on the roccamonfina volcanic rocks, roman magmatic province, southern italy. contribution to mineralogy and petrology, 157, 41-63. d'angela d., longinelli a. (1990) oxygen isotopes in living mammal's bone phosphate: further results. chemical geology, isotope geoscience section, 86, 75-82. lugli f., cipriani a., peretto c., mazzucchelli m., brunelli d. (2017a) in situ high spatial resolution 87 sr/ 86 sr ratio determination of two middle pleistocene (ca. 580 ka) stephanorhinus hundsheimensis teeth by la-mc-icp-ms. international journal of mass spectrometry, 412, 38-48. lugli f., cipriani a., arnaud j., arzarello m., peretto c., benazzi s. (2017b) suspected limited mobility of a middle pleistocene woman from southern italy: strontium isotopes of a human deciduous tooth. scientific reports, 7, 8615. pellegrini m., lee thorp j.a., donahue r.e. (2011) exploring the variation of the δ 18 op and δ 18 oc relationship in enamel increments. palaeogeography, palaeoclimatology, palaeoecology, 310, 71-83. peretto c., arnaud j., moggi-cecchi j., manzi g., nomade s., pereira a., falguères c., bahain j.j., grimaud-hervé d., berto c., sala b., lembo g., muttillo b., gallotti r., thun hohenstein u., vaccaro c., coltorti m., arzarello m. (2015) a human deciduous tooth and new 40 ar/ 39 ar dating results from the middle pleistocene archaeological site of isernia la pineta, southern italy. plos one, 10, e0140091. human and animal mobility at isernia la pineta ms. received: may 7, 2018 final text received: may 19, 2018 82 sess 1_160211.pub il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 gelasian to calabrian onland marine record: three case studies in the mediterranean area angela baldanza 1, roberto bizzarri 2, federico famiani 3, irene luccioni 4 & paolo pino 5 1 dipartimento scienze della terra, università di perugia, perugia 2 via a. capitini, 8-06055 marsciano (pg) 3 via monteverde, 16-06029 valfabbrica (pg) 4 via c. colombo-60021camerano (an) 5 dipartimento scienze della terra-università di messina, messina corresponding author: r. bizzarri <roberto.bizzarri@libero.it> abstract: baldanza a. et al., gelasian to calabrian onland marine record: three case studies in the mediterranean area. (it issn 0394-3356, 2011) neogene to quaternary marine sedimentation along the italian peninsula occurred into physiographical articulated basins and was characterized by a paleoenvironmental diversification, both nearshore and offshore. nevertheless, the nannofossil biostratigraphy allows comparisons in the mediterranean area, also in the case of on-land sections. three case studies are here proposed, testifying the importance of calcareous nannofossils also to correlate on-land sections throughout italian neogene deposits. riassunto: baldanza a. et al., record marino del gelasiano-calabriano su serie a terra: tre casi di studio nell’area mediterranea. (it issn 0394-3356, 2011) la sedimentazione marina lungo la penisola italiana, durante il neogene e il quaternario, ha avuto luogo entro bacini dalla fisiografia articolata e riflette differenze sia in ambiente costiero che distale. tuttavia, la biostratigrafia a nannofossili permette correlazioni nell’area mediterranea, anche nel caso delle successioni a terra. tre situazioni vengono proposte in questa sede, nell'intento di mostrare la fondamentale importanza dei nannofossili calcarei anche nelle correlazioni di successioni a terra di depositi neogenici italiani. key words: nannofossil stratigraphy, mediterranean area, gelasian, calabrian. parole chiave: stratigrafia a nannofossili, mediterraneo, gelasiano, calabriano. the evolution of coastal marine environments along the italian peninsula, throughout the neogene and the quaternary, is related to the late phases of the apennine chain foredeep basin foreland eastward migration, and to the opening of the thyrrenian sea. the pliocene and pleistocene marine successions have been deposited into physiographical articulated basins and are characterized by a paleoenvironmental diversification, taking place on coastal environments as well as on basin deposits. nevertheless, foraminifer and calcareous nannofossil stratigraphy allow to compare deeply different situation in the mediterranean area, also in the case of onland sections: three case studies are here proposed (fig. 1). 1 the western umbria plio-pleistocene marine record, from città della pieve to orvieto (central italy) is characterized by shallow marine deposits, varying from gravel to sand, to clay (ambrosetti et al., 1987; bizzarri, 2006). the evolution of the area among pliocene and pleistocene has been described in terms of two main sedimentary cycles, referable to piacenzian pp. and gelasian pp. santernian, respectively, and separated by the “acquatraversa” stratigraphic gap (ambrosetti et al., 1987; girotti & mancini, 2003; mancini et al., 2004). coastal paleomorphologies varied from rocky coasts to deltaic coasts, to sand and gravel beaches locally fed by fan deltas (bizzarri et al., 2005; bizzarri, 2006, 2007, 2010; bizzarri & baldanza, 2009). the documented facies heteropy is due to lateral subenvironmental variations, inherited from previous subaerial evolution of landscape, and testifies of a complex shoreline articulation. on the other hand, deposits distally homogenize to silty sand (transition to offshore) and clay/silty clay (offshore). analyses on both calcareous nannofossils and foraminifers lead to a stratigraphic review (bizzarri et al., 2004; bizzarri, 2006; bizzarri & baldanza, 2006). the recent documentation of still unknown volcanic events, in the mnn 19b to mnn 19d stratigraphic interval (bizzarri et al., 2003; famiani, 2010; peccerillo et al., in press), represents another fine stratigraphic tool to compare onland sections. 2 the underground camerano town (ancona, central italy) allows to describe a composite sedimentological and stratigraphical section into early pleistocene marine deposits (luccioni, 2007; baldanza et al., 2010b), attributable to the qm-a3 phase (cantalamessa et al., 1986; centamore et al., 1991, 2009; centamore & micarelli, 1997; 17 19 18 centamore & nisio, 2003). deposits are mainly characterized by yellow-brown sand and greygreen clay couplets; in the uppermost and in the middle cave system, matrix-supported gravel horizons also occur. sand-clay couplets are interpreted as carbonatic turbidites (baldanza et al., 2010b). the large clay fragments, matrixsupported gravels probably derive from seismic remobilization of partially lithified deposits along the basin’s flank. deposits suggest the sedimentation in a tectonically active basin, with mixed distal river and stormto seismic-induced carbonatic turbidites deposits; nevertheless, biostratigraphic analyses on nannofossil content allow to refer them to early pleistocene (mnn 19c nannofossil subzone: rio et al., 1990). 3 the north-eastern sicily marine grey-blue clay deposits have been recently re-evaluated and mapped (pino et al., 2007, 2009; triscari et al., 2007; baldanza et al., 2010a), with the aim to better define the stratigraphic range. the nannofossil analyses allow to integrate the local stratigraphic succession (kezirian, 1992; di stefano & lentini, 1995; maccarrone et al., 2000). in the messina province, on the tyrrhenian side of the peloritani mts., the most important clay unit (about 70m thick) has been studied in the venetico and c.da scarano outcrops, and the mnn 19e and mnn 19f subzones have been recovered. other reduced exposures, in the eastern villafranca tirrena area (c.da baronello, massa s. lucia), also document the presence of mnn 19b to mnn 19d subzones. the occurrence of volcanic materials, still in the early-middle pleistocene clay deposits of the tyrrhenian side, is also reported (casella et al. 2006; pino et al., 2007). on the ionian side of sicily, early pleistocene clay deposits are firstly reported in the nearby of giardini naxos (pino et al., 2007; baldanza et al., 2010a). the comparison of the three case study is an example of the large affidability of nannofossils as stratigraphic marker, which confirms the identification, also in the onland sections, of the same nannofossil events as in the mediterraean odp pits, in the same order, and shows the applicability to onland sections of the standard mediterranean neogene nannofossil scales. references ambrosetti, p., carboni m. g., conti m. a., esu d., girotti o., la monica g. b., landini b. & parisi g. 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(2007) clay units in ne sicily: an integrated map and database finalized to archaeometric provenance studies. geoitalia epitome, 2, p. 469. gelasian to calabrian onland marine record: ... january 14, 2011 14 gennaio 2011 amq abs pascucci et al saccom 181-184.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 181 184 late quaternary stratigraphy of western sardinia (central mediterranean) based on luminescence age dating vincenzo pascucci 1, stefano andreucci 2, daniele sechi 1, leonardo casini 2 1 dipartimento di architettura, design e urbanistica, università di sassari, sassari, italy 2 diparimento di scienze chimiche e geologiche, università di cagliari, cagliari, italy 3 dipartimento di chimica e farmacia, università di sassari, sassari, italy corresponding author: v. pascucci <pascucci@uniss.it> abstract: we present the revised stratigraphic setting of the late quaternary deposits cropping out along the western coast of sardinia (italy). the height defined units have been dated using luminescence. keywords: osl, climate changes, eemian, marine isotopic stages 1. introduction numerous scientific models suggest that in 2100 the global temperature will be about 2 °c higher than today, with consequent rise of the sea level (antonioli et al., 2017). main effect of these rapid variations will result in a radical change of the coastal geography of the entire planet. however, no one model considers: 1) the adaptability of natural systems to the new physical conditions, 2) the differences between less and more urbanized coasts and, 3) the behaviour of areas with different tectonic regimes. investigating how the coastal plains reacted in the past in response to climate changes is one of the keys to hypothesise possible future scenarios in the short/medium term (amorosi et al., 2018). it is therefore necessary an accurate study of the climate/ sea-level changes of the past glacial-interglacial cycles and recent warm-cold holocene fluctuations to improve the climate-changes future projections. to define the coastal response to the high and very high frequency glacio-eustatic fluctuations of the late quaternary (last 300 ka) and in particular of the last interglacial (125-85 ka) becomes of utmost importance (amorosi et al., 2005; vacchi et al., 2016). the marine palaeosea level markers consist of various erosive (tidal notches, raised marine terraces), sedimentary (palaeo-beaches and coral reefs) and stratigraphic (transgressive/regressive successions) features useful to estimate the palaeo-sea level (de muro & orrù, 1998; pascucci et al., 2009; antonioli et al., 2015). they, however, are reliable if used in tectonically stable areas and precisely age dated. the use of an absolute dating methodology for these sedimentary and stratigraphic marine palaeosea-level markers may provide a unique opportunity to precisely define the chronology of the response of the coastal systems to sea-level changes, and define the climatic changes occurred from the middle pleistocene. 2. material and methods the west and northwest coasts of sardinia have been chosen as a case study, because the island is generally considered stable, being tectonically inactive since 1 ma (fig. 1). the adopted absolute dating methodology is the luminescence (murray & wintle, 2000; buylaert et al., 2011). the west and northwest coasts of sardinia are quasi continuously draped by late quaternary strata overlapping the older substrate. they have been referred by authors to either the tyrrhenian interglacial, if characterised by marine deposits resting above the present sea level, or to the “wurmian” glacial if continental. just few are referred to the “riss” glacial phase (carboni & lecca, 1985; carmignani et al., 2001). according to the modern marine isotope stratigraphy (mis) adopted for quaternary studies, a deep review of the stratigraphy, especially adopting absolute dating methodologies is needed. fig. 1 sardinia island (italy) in the center of the mediterranean sea. https://doi.org/10.26382/aiqua.2018.aiquaconference given the limit of 14c for dating sedimentary deposits older than 45 ka, several different dating methods have been recently tested to date the late quaternary succession of west and northwest sardinia (i.e. u/th, aminoacid racemisation, and luminescence) (i.e. andreucci et al., 2009, 2010, 2014, 2017; thiel et al., 2010). however, due to the clastic nature of these deposits, the luminescence is the most suitable methodology. the method estimates the time elapsed since the last exposure to sunlight of quartz (optically stimulated luminescence) and alkali feldspar (post ir irsl 290) grains and thus enabling us to constrain the burial time. 3. results and discussion the revised late quaternary stratigraphy of the west and northwest coasts of sardinia enabled us to identify the role played by sea level and climate changes, in controlling sedimentation. the luminescence dated outcropping succession, has been grouped into eight major stratigraphic units mainly represented by coastal dunes, shallow marine and alluvial systems (pascucci et al., 2014). these units range in age from mis 8 (300 ka) to mis1 (last 11.8 ka) (fig. 2). data provided are not useful to clearly define what happened between mis 8 and 7. it is, however, worthy to note that in some areas marine mis7 deposits crop out above the present sea level. this could imply that the claimed tectonic stability of the island needs to be revised. mis6 deposits are scattered and discontinuous. they are mostly made by gravity flow and occasional wind dominated systems. a better dataset encompasses the last 125 ka and allows inferring the climatic events occurred during the last interglacial (mis 5) and glacial (mis 4-2) times. mis5 is subdivided in five substages (e-a). mis5e (eemian) is considered the climate optimum of this interglacial. in sardinia the sea level was 4-6 m higher than today and climate conditions were warmer and more humid. during this high stand sea level, not many beaches developed, whereas tidal notches and bioherms were common. the last have been herein dated for the first time with luminescence and range in age from 138 to 114 ka. mis 5c (110 -95 ka) is the second high stand peak. the error of the luminescence technique, however, does not allow discriminating mis5e and 5c. the stratigraphic data, in any case, indicate that around 100 ka a sea level still stand occurred. during this time, the sea level was about 1.5 m higher than todays, several sandy beaches developed, and palaeoclimatic and palaeogeographic conditions were similar to the present time. during the following mis 4, at the beginning of the glacial phase, a climatic deterioration occurred; temperature decreased of about 6 °c with respect to mis 5e. luminescence datings indicate that this deterioration was brief and rapid (5 to 10 ka). as a result, the sea level drops of about 60 m, the inland vegetation cover progressively educed, and a denudation of valley slopes repeatedly occurred. the sea-level fall created the accommodation space for the development of alluvial fans in sheltered and cliffy areas, where debris flows accumulated and filled almost completely the terminal parts of the narrow coastal valleys/coves, while on wider areas coastal dune fields developed. contemporaneous occurrence of alluvial fan and dune systems is associated to the local morphology that could mitigate or amplify some moistly conditions in a general arid environment. during mis 3 alternate deposition of alluvial/fluvial and aeolian sediments document the occurrence of several climate fluctuations. they could be related with the wet/arid, d/o-h events (heinrich & dansgaard– oeschger events) that have been recognised in the cold mis3 (pascucci et al., 2014). these fluctuations, each 182 pascucci v. et al. fig. 2 relationships and main features of the eight unconformity bounded units cropping out along the west and northwest coast of sardinia. units cover the last 300 ka. right columns report the estimated sea level elevations and temperatures from marine isotopic stage 5 (mis 5) to mis1 (modified after pascucci et al., 2014). lasting about 10 ka, are beyond the luminescence resolution. according to the available dating, we could just document that the shallow sardinian shelf was continuously exposed throughout the mis3, being the source area of bioclastic sands. these sands were blown inland, and formed extensive dune field systems. dunes dominated the west coast of sardinia under cold and relatively dry conditions. in some areas, these dune field systems were eventually almost completely dismantled and reworked into water-flow dominated alluvial fans by catastrophic rainfall events occurred during relatively more humid conditions. thus, the local climate quickly switched from arid to humid. no record of the last glacial maximum deposits, mis 2, was observed along the nw sardinian coast. submarine data just confirm that the lowest sea level was of -120 m below the present. during the holocene transgression (mis 1) the coastline progressively migrated landward as the coastal dune systems did. the temperature aumented, reaching almost the present-day values around 6ka. since this time onward, little sea-level and climatic fluctuations occurred, leading to transgressive/regressive cycles of few thousands of years. mis1 deposits have been dated, when possible, also using 14c technique (pascucci et al., 2018). this cross-methodology has always proven the reliability of the results obtained by means of the luminescence method. 4. conclusions we have documented that late quaternary continental and shallow marine deposits may be dated using luminescence methodology both on quartz and kfeldspar grains. at the moment the erorr comprised between 10 and 5% does not allow distinguishing high frequency cycles of the order of 10 to 5 ka, but just to claim their existence. acknowledgements the authors thanks alessandra negri for the provided review that helped to improve the manuscript. this work was supported by: accordo di cooperazione ex art. 15 della legge 7, agosto 1990 n. 241 between the municipality of alghero, manager of marina protected area “capo caccia – isola piana” and department of architecture, design and planning of the university of sassari (resp. prof. vincenzo pascucci). references amorosi a., centineo m.c., colalongo m.l. fiorini f. 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(2000) luminescence dating of quartz using an improved single-aliquot regenerative-dose protocol. radiat. meas., 32, 57-73. pascucci v., martini i. p, endres a. (2009) facies and ground-penetrating-radar (gpr) characteristics of coarse-grained beach deposits of the uppermost pleistocene glacial lake algonquin, ontario canada. sedimentology, 56, 529-545. pascucci v., de falco g., del vais c., melis r., sanna i., andreucci s. (2018) climate changes and human impact on the mistras coastal barrier system (w sardinia, italy). mar. geo., 395, 271284. pascucci v., sechi, d., andreucci s. (2014) middle pleistocene to holocene coastal evolution of nw 183 late quaternary stratigraphy of western sardinia sardinia (mediterranean sea, italy). quat. int., 328 -329, 3-20. thiel c., coltorti m., tsukamoto s., frechen m (2010) geochronology for some key sites along the coast of sardinia (italy). quat. int. 222, 36-47. vacchi m., marriner n., morhange c., spada g., fontana a., rovere a. (2016) multiproxy assessment of holocene relative sea-level changes in the western mediterranean: sea-level variability and improvements in the definition of the isostatic signal. earth-science reviews, 155, 172-197. 184 pascucci v. et al. ms. received: may 7, 2018 final text received: may 14, 2018 available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 13 16 first results on the coastal changes related to local sea level variations along the puteoli sector (campi flegrei, italy) during the historical times pietro p.c. aucelli 1 , aldo cinque 2 , gaia mattei 1 , gerardo pappone 1 , michele stefanile 3 1 dipartimento di scienze e tecnologie, università degli studi di napoli parthenope, napoli, italy 2 dipartimento di scienze della terra, dell’ambiente e delle risorse, università di napoli federico ii, napoli, italy 3 dipartimento asia africa e mediterraneo, università l’orientale di napoli, napoli, italy corresponding author: g. mattei <gaia.mattei@uniparhtenope.it> abstract: puteoli coastal sector is located in the campi flegrei volcanic area, along the mediterranean coasts. this sector is rich in archaeological remains here used as sea-level markers useful to reconstruct the vertical ground movements affecting the cf area. marine surveys by means of an unmanned surface vessel equipped with geophysical instruments were carried out along the coastal sector to reconstruct the seabed morphology and to detect the submerged remains. by analysing geomorphological stratigraphic and archaeological data, the natural and anthropogenic landscape evolution of puteoli since the greek-roman period was evaluated. keywords: campi flegrei volcanic area; vertical ground movements; sea level markers; coastal changes 1. introduction the puteoli coast is located in the central part of campi flegrei caldera, an active volcanic system whose activity spans the last 50,000 years (de vivo et al., 2010 and reference therein). the caldera formation is mainly related to the campanian ignimbrite (ci, 37 ky) and the neapolitan yellow tuff (nyt; 15 ky) eruptions. this area is well known for bradyseism crisis characterized by alternating phases of intense uplift and subsidence of different duration. these vertical ground movements (hereinafter vgm) have produced strong modification in the coastal landscape since the early holocene. la starza marine terrace is the oldest silent witness of this volcanic behaviour. in fact, this marine terrace uplifted 30-40 m a.s.l. about 5 ky bp (di vito et al., 1999 and reference therein). instead, the more recent historical coastal modifications are mainly testified by the submerged structures of portus julius and by the lythophaga perforations on the marble columns of the macellum, the roman food market so-called serapis temple (morhange et al., 2006 and reference therein). despite the repeated modifications of the coastal landscape, this sector was extensively inhabited since the greek time, as testified by the town of dicearchia (531 bc) and by the neighbouring greek colony of kyme (the oldest in the western mediterranean, according to the ancient authors). however, it reached its maximum expansion during the roman period with the settlement of the roman colony of puteoli (194 bc), in the same site of the samian dicearchia, where a portorium was created during the second punic war. during this period, several human adaptations to bradyseismic crisis that affected the campi flegrei area were necessary (aucelli et al, 2017a, b and c). the studies have demonstrated that these vgms are not distributed uniformly all over the coast and new data can improve the knowledge on the phenomenon. in this short communication, we present the first result of a geoarchaeological study of the area located off the puteoli coast at the footslope of la starza marine terrace that still preserves several traces of coastal changes affecting campi flegrei area during the greekroman period due to vgms. 2. methods the greek-roman sea level changes and its effects on the coasts were deduced by interpreting depositional, erosional, biological and archaeological markers (vacchi et al., 2016 and references therein). in the first instance, the coastal sector was investigated by means of an unmanned surface vessel (usv) equipped with geophysical systems and underwater cameras as well as by direct underwater surveys. the usv was engineered by our research group to carry out integrated surveys with acoustical and optical methods at the same time in very shallow waters sectors (giordano et al., 2015; 2016). the analysis of the morpho-acoustic data allowed reconstructing the seabed morphology and the submersion of all submerged archaeological structures (mattei and giordano 2014; aucelli et al., 2016), as the pilae well distributed in the study area and probably dated by historical sources at augustan period (31 bc 14 ad). by https://doi.org/10.26382/aiqua.2018.aiquaconference mailto:gaia.mattei@uniparhtenope.it correcting the present submersion with respect to the indicative meaning (the elevation where the marker was built with respect to the palaeo-sea level, vacchi et al., 2016 and references therein), a new palaeo-sea level was deduced. three palaeo sea-level dated at greek-roman period were identified by reinterpreting a stratigraphic record close to the macellum (bellucci et al., 2006), taking into account the archaeological constrains provided by the restorations in this complex and by the portus julius construction. the main evolutive steps of the coastal sector in the same period were deduced by analysing highresolution morphologic (lidar, single beam and multibeam bathymetry) and geological data as well as by interpreting all submerged archaeological remains located in the study area. 3. results puteoli coastal sector has suffered short-lived subsidence phases in the historical times which greatly amplified the effects of the eustatic sea level rise (lambeck et al., 2011), producing the submersion of wide areas. the sea level deduced by studying the 74 submerged pilae, probably built not before the augustan age and well distributed off the southern puteoli coastal sector are an important evidence of a coastal retreat. as the more preserved pila has the top surface at -1 m bsl and considering an indicative range not higher than 2 m, the 1 st century ad sea level was no lower than -3 m. a previous sea level at -6 m was deduced by the present submersion of the portus julius entry channel (passaro et al., 2013). in fact, this military port was hastily built in 37 bc, as a new resource for the war against the pirates, and abandoned in a few years for the rapid submersion of port facilities (todesco et al., 2014). we can deduce a subsidence about of 3 m that also explains the construction of the pilae as a coastal defence during the augustan age. two other relative sea level between the 1 st century bc and 1 st century ad were deduced by reinterpreting a stratigraphic record close to the famous macellum probably built in the i century ad, in a place where also a 1st mosaic floor was discovered, probably dated at mid-ii century bc by several authors (i.e. dvorak & mastolorenz, 1991; todesco et al., 2014). a sea level dated at the time of the construction of the first structures in this site was evaluated not higher than 8 m by bellucci et al. (2006), thanks to the anthropogenic deposits (with pottery fragments) on which the first floor lies. consequently, we have calculated a subsidence phase between ca. 150 bc and 37 bc about of 2 m. the 1 st floor was totally buried by 2 m of coarse sands that can be interpreted as an antrophic intervention aimed at the construction of the 2 nd marble floor. the last relative sea level at -2 m b.s.l. was deduced from the position of the second marble floor (probably dated at flavian age), the second in the sequence of the site, at 0.086 m a.s.l. (by supposing 2 m of indicative meaning). 4. discussion and conclusion this study has provided new data related to greekroman vertical ground movements affecting the campi flegrei, by means of a precise detection of four local palaeo-sea level indicators. in the first instance, a new palaeo-sea level probably dated not before the augustan period (camodeca, 1994) was evaluated by sensing the underwater archaeological landscape of this sector by using a usv with geophysical instruments. the corresponding coastline position at that time was reconstructed by integrating the geophysical, geomorphological and archaeological interpretations (figure 1). thanks to these interpretations, a subsidence occurred between 37 bc and the 1st century ad was evaluated for the first time, by overlaying the sea level data deriving from the submersion of the defence structures (pilae) here studied with that of portus julius (passaro et al., 2013) built several years before the pilae. in the second instance, the reinterpretation of the stratigraphic record described by bellucci et al. (2006) allowed us to evaluate the two other palaeo-sea level as well as the corresponding coastline positions (figure 1). two subsidence phases deriving from these interpretations were obtained: one between ca. 150 bc and 37 bc, and another during the of 1 st century ad. taking into account that the eustatic sea level during this time lapse was constantly at -1.1 m b.s.l. (aucelli et al., 2017; lambeck et al., 2011), the subsidence of about 3 m can be ascribed to a volcano tectonic ground movement. the vertical ground movements of metric entity here tentatively proposed between 2 nd century bc and 1 st century ad, can be totally ascribed to a volcanotectonic origin, taking into account that the eustatic sea level rise during this time lapse ranged between -1.38 m and 1.06 m (aucelli et al., 2017; lambeck et al., 2011). taking into account that the eustatic sea level rise during this time lapse ranged between -1.38 m and 1.06 m (aucelli et al., 2017; lambeck et al., 2011), these vertical ground movements of metric entity can be totally ascribed to a volcano-tectonic origin. at that time, this study provides a first evaluation of the subsidence effects on the campi flegrei coastal landscape and coastal settlements during the historical times, thanks to the reconstruction of the local sea level variations between the 2 nd century bc and the 1 st century ad (figure 1). in conclusion, the historical coastal evolution of the central part of campi flegrei caldera has been characterized by a coastal retreating about of 150 m. the coastline positions here reconstructed between 200 bc and 14 ad have enabled us to assess this trend. this study has demonstrated as the puteoli coastal landscape was strongly modified by volcano-tectonic movements inducing fast sea level variations. these coastal changes were reconstructed by overlaying geomorphological archaeological and stratigraphic interpretations in order to describe the interaction between landforms evolution and human adaptations. moreover, the ongoing acquisition of new archaeological data could slightly vary some geochronological constraints related to the macellum construction phases. 14 aucelli p.p.c. et al. 15 fig. 1 a) relative sea level curve since the greek-roman times; b) 3d landscape with the roman structures nowadays submerged and the coastline positions between the 2nd century bc and 1st century ad. historical evolution and sea level changes of puteoli coastal sector references aucelli p.p.c., cinque a., mattei g., pappone g., stefanile m. (2017) coastal landscape evolution of naples (southern italy) since the roman period from archaeological and geomorphological data at palazzo degli spiriti site. quaternary international, in press. doi: 10.1016/j.quaint.2017.12.040 aucelli p.p.c., cinque a., mattei g., pappone g. (2017) late holocene landscape evolution of the gulf of naples (italy) inferred from geoarchaeological data. journal of maps, 13 (2), 300-310. aucelli p.p.c., cinque a., mattei g., pappone g., rizzo a. (2017) studying relative sea level change and correlative adaptation of coastal structures on submerged roman time ruins nearby naples (southern italy). quaternary international, doi: 10.1016/j.quaint.2017.10.011 aucelli p.p.c., cinque a., mattei g., pappone g. (2016) historical sea level changes and effects on the coasts of sorrento peninsula (gulf of naples): new constrains from recent geoarchaeological investigations. palaeogeography, palaeoclimatology, palaeoecology, 463, 112-125. aucelli p.p.c., cinque a., giordano f., mattei g. (2016) a geoarchaeological survey of the marine extension of the roman archaeological site villa del pezzolo, vico equense, on the sorrento peninsula, italy. geoarchaeology, 31 (3), 244-252. bellucci f., woo j., kilburn c. r., rolandi g. (2006) ground deformation at campi flegrei, italy: implications for hazard assessment. geological society, london, special publications, 269(1), 141157. camodeca g. (1994) puteoli porto annonario e il commercio del grano in età imperiale. publications de l'école française de rome, 196(1), 103-128. de vivo b., petrosino p., lima a., rolandi g., belkin h. e. (2010) research progress in volcanology in the neapolitan area, southern italy: a review and some alternative views. mineralogy and petrology, 99(1-2), 1-28. di vito m., isaia r., orsi g., southon j., de vita s., d’ antonio m., pappalardo l., piochi m. (1999) volcanism and deformation since 12,000 years at the campi flegrei caldera (italy). journal of volcanology and geothermal research, 91(2), 221-246. dvorak j.j., mastrolorenzo g. (1991) the mechanisms of recent vertical crustal movements in campi flegrei caldera, southern italy. geological society of america, 263, 1-47. giordano f., mattei g., parente c., peluso f., santamaria r. (2015) microvega (micro vessel for geodetics application): a marine drone for the acquisition of bathymetric data for gis applications. the international archives of photogrammetry. remote sens. spatial inf. sci., 40 (5), 123-130. giordano f., mattei g., parente c., peluso f., santamaria r. (2016) integrating sensors into a marine drone for bathymetric 3d surveys in shallow waters. sensors, 16 (1), 41. lambeck k., antonioli f., anzidei m., ferranti,l., leoni g., scicchitano g., silenzi s. (2011) sea level change along the italian coast during the holocene and projections for the future. quaternary international, 232(1-2), 250-257. mattei g., giordano f. (2015) integrated geophysical research of bourbonic shipwrecks sunk in the gulf of naples in 1799. j. archaeol. sci. rep. 1, 64-72. morhange c., marriner n., laborel j., todesco m., oberlin c. (2006). rapid sea-level movements and non eruptive crustal deformations in the phlegrean fields caldera, italy. geology, 34, 93-96. passaro s., barra m., saggiomo r., di giacomo s., leotta a., uhlen h., mazzola s. (2013) multiresolution morpho-bathymetric survey results at the pozzuoli-baia underwater archaeological site (naples, italy). journal of archaeological science, 40(2), 1268-1278. todesco m., costa a., comastri a., colleoni f., spada g., quareni f. (2014) vertical ground displacement at campi flegrei (italy) in the fifth century: rapid subsidence driven by pore pressure drop. geophysical research letters, 41(5), 1471-1478. vacchi m., marriner n., morhange c., spada g., fontana a., rovere a. (2016) multiproxy assessment of holocene relative sea-level changes in the western mediterranean: sea-level variability and improvements in the definition of the isostatic signal. earth science reviews, 155, 172-197. 16 aucelli p.p.c. et al. ms. received: may 8, 2018 final text received: june 3, 2018 amq abs zerboni et al tepro 253-256.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 253 256 towards a map of the upper pleistocene loess of the po plain loess basin (northern italy) andrea zerboni 1, rivka amit 2, carlo baroni 3, mauro coltorti 4, m. francesca ferrario 5, gianfranco fioraso 6, m. gabriella forno 7, chiara frigerio 5, franco gianotti 7, andrea irace 6, franz livio 5, guido s. mariani 1, alessandro m. michetti 5, giovanni monegato 6, paolo mozzi 8, giuseppe orombelli 9, alessandro perego 1, naomi porat 2, ivano rellini 10, luca trombino 1, mauro cremaschi 1 1 dipartimento di scienze della terra “a. desio”, università degli studi di milano, milano, italy 2 geological survey of israel, jerusalem, israel 3 dipartimento di scienze della terra, università degli studi di pisa, pisa, italy 4 dipartimento di scienze fisiche, della terra e dell’ambiente, università di siena, siena, italy 5 dipartimento di scienza e alta tecnologia, università degli studi dell’insubria, como, italy 6 igg cnr, torino, italy 7 dipartimento di scienze della terra, università degli studi di torino, torino, italy 8 dipartimento di geoscienze, università degli studi di padova, padova italy 9 dipartimento di scienze dell’ambiente e della terra, università degli studi di milano-bicocca, milano, italy 10 dipartimento del territorio e delle sue risorse, università di genova, genova, italy corresponding author: a. zerboni <andrea.zerboni@unimi.it> abstract: upper pleistocene (mis 4–2) loess sequences occur in most of continental europe and in northern italy along the po plain loess basin. loess is distributed along the flanks of the po plain and was deposited on glacial deposits, fluvial terraces, uplifted isolated hills, karst plateaus, slopes and basins of secondary valleys. loess bodies are generally tiny and affected by pedogenesis, being locally slightly reworked by slope processes and bioturbation. notwithstanding, loess in the po plain is an important archive of paleoenvironmental record and its mapping provides new insights in paleoenvironmental and palaeoseismic reconstructions of northern italy. keywords: loess, po plain loess basin, upper pleistocene, mapping 1. introduction in the framework of european terrestrial palaeorecords, loess is one of the best archives for quaternary palaeoenvironmental reconstruction (e.g. smalley & leach, 1978; coudé-gaussen, 1990; pye, 1995; cremaschi, 2004). maps published in the last decade that present the distribution of loess in europe eliminate loess outcrops in northern italy or, alternatively, define them as loess derivates (haase et al., 2007; bertran et al., 2016; lindner et al., 2017). as a consequence, despite systematic studies carried out on the upper pleistocene loess sequences at the margin of the po plain (see cremaschi, 1987, 2004 and references therein), loess in northern italy is overlooked in comparison to the classical sequences described in continental europe (amit & zerboni, 2013), and crucial data are excluded from the interpretation of loess formation at a continental scale. for this reason, in the last few years we revised the sedimentological, paleoenvironmental, and geochronological data regarding the loess from the po plain loess basin (pplb), including new data derived from studying some classical loess outcrops (e.g., ferraro, 2009; wacha et al., 2011; cremaschi et al., 2015; cremaschi & zerboni, 2016), as well as freshly identified sequences (e.g., rellini et al., 2009; zerboni et al., 2015; frigerio et al., 2017). moreover, in a region the po plain foredeep of moderate seismicity loess is a stratigraphic marker of increasing interest for earthquake hazard characterization (e.g., livio et al., 2014). to provide the necessary spatial context for these tasks, a systematic mapping of loess outcrops along the po plain is on-going and preliminary results are here discussed. 2. the po plain loess basin loess is a wind-blown, mainly silty-sized sediment. it is widespread in northern italy, where it is typical of glacial periods, when sediment grinding (weathering), transportation, and sedimentation are enhanced by dry environmental conditions with poor vegetation cover and characterized by strong winds (cremaschi, 1990; orombelli, 1990; pye, 1995). except for a few thick sequences of unweathered loess deposits (as the val sorda sequence) and/or complex pedosequences (as at monte netto), most of the outcrops in northern italy consist of thin loess sheets located on dissected fluvial terraces, glacial deposits, uplifted isolated hills, and karst plateaus (fig. 1). these are for the most part set along the southern margin of the alps and the northern margin of the apennines. loess sequences can also be found on top of polygenetic paleosols, inside sinkholes, and intercalated in rock-shelter deposits. furthermore, loess deposits in northern italy are often associated with middle palaeolithic archaeohttps://doi.org/10.26382/aiqua.2018.aiquaconference logical sites, showing that the po plain loess basin (pplb) was a suitable environment for mousterian hunter-gatherers. available chronology, based on a number of radiocarbon, tl, and osl dating suggests that the formation of loess occurred during the upper pleistocene, between at least 75 and 16 ka bp (mis 4-2) (cremaschi, 2004; zerboni et al., 2015). thicker sequences (as at ghiardo and monte netto sites) also record weak to moderate soil-forming processes dating to the upper pleistocene interstadials and the holocene. at many sites, the uppermost part of loess sequences likely underwent moderate to strong reworking due to post-last glacial maximum (post-lgm) reactivation of slope processes, enhanced holocene bioturbation, and, more recently, human-induced processes (tillage). as a result, colluvial and bioturbated units/soil horizons were formed, whose 14c and osl dating provided midholocene ages that are interpreted as due respectively to the mixing of soil humic acids over a long time and rejuvenation of dose signal. this has been demonstrated at monte netto and ghiardo sequences (cremaschi et al., 2015; zerboni et al., 2015). 3. drawing the loess map the available geological maps present loess deposits only fragmentarily, as layers inside or at the top of quaternary formations, without providing any information on the sedimentary and post-sedimentary (pedogenetic) processes affecting loess covers. on the other hand, the available pedological maps suggest the occurrence of silt-bearing soil horizons, but interpretations of sedimentary processes ruling the accretion of silt are lacking. a few attempts to reconstruct the spatial distribution of loess in the pplb have been preliminary published by cremaschi (2004), cremaschi et al. (2015), zerboni et al. (2015); moreover, the climex map 254 fig. 1 some loess outcrops investigated in the last few years. a) the val sorda sequence (cavaion veronese, vr): loess lies on a glacial deposit. b) loess at the margin of the apennine (cavriago, re) (cremaschi et al., 2015). c) the monte netto (capriano del colle, bs) sequence (zerboni et al., 2015), displaced by an array of normal faults (i.e., gravity graben). d) loess sequence at pecetto di valenza (al) (frigerio et al., 2017). zerboni a. et al. 255 of the lgm (vai & cantelli, 2004) offers a good representation of many loess outcrops. for these reasons, the publication of a new map presenting the spatial distribution of loess is necessary and relies on field surveys in key regions, integrated by observations on (i) geological contexts and (ii) active and inactive surface processes. at the first stage, we will identify and study landforms acting as sedimentary traps for loess aggradation (cremaschi, 2004), such as: (i) glacial sediments (moraines) and fluvioglacial deposits at the southern fringe of the pre-alps; (ii) karst plateaus (and sinkholes) between lombardia and the dalmatian coast, and in the conero promontory (marche region); (iii) isolated hills in the middle of the po plain, actively growing through repeated coseismic uplift during the late quaternary; (iv) fluvial terraces of different ages on the apennine foothills between southern piemonte, emilia romagna and marche regions; (v) glacis and erosional surfaces in the apennine range of marche, emilia romagna, and liguria regions, where sedimentation can be influenced by the pre-existing topography. in the map, loess outcrops will be represented distinguishing between: (i) unweathered loess; (ii) weathered loess and loessial soils displaying different degrees of weathering and characterized by distinctive soil-forming processes; and (iii) colluvial/reworked loessic sediments (loess derivates). at a second stage, a more detailed classification of loess units will be under evaluation. this will offer a better comprehensive palaeoenvironmental context in the light of the maximum expansion of alpine and apennine glaciers and the shoreline of the adriatic sea during the lgm, which will be included in our map as reconstructed in the climex map (vai & cantelli, 2004). 4. preliminary conclusions because loess deposits in northern italy are generally thin and can be easily affected by soil-forming processes, sometimes their characteristics do not fully meet the standard requirements generally accepted for classical loess (haase et al., 2007). although loess deposits and loessial soils in the po plain are slightly different, the main sedimentological and pedological characteristics are similar in their field appearance, particle size distribution, and mineralogy, thus suggesting a similar source. the source area was identified as the po flood plain, which was exposed during glacial periods and was subject to intense winds at that time. the investigation of several key sequences and the systematic mapping of outcrops are demonstrating the importance of north italian loess for the reconstruction of upper pleistocene palaeoclimates of the northern mediterranean region and the paleoseismic record of the po plain foredeep. acknowledgements this research has been carried out within the activities of the inqua geodust international focus group. financial support from università degli studi di milano, progetto linea 2 (2016 and 2017) entrusted to az. references amit r., zerboni a. (2013) report on the inquaaeomed field-trip workshop ‘reconsidering loess in northern italy’ (po plain, 1–3 july 2013). alpine and mediterranean quaternary, 26, xi-xv. bertran p., liard m., sitzia l., tissoux h. (2016) a map of pleistocene aeolian deposits in western europe, with special emphasis on france. journal of quaternary science, 31, 844-856. coudé-gaussen g. (1990) the loess and loess-like deposits along the sides of the western mediterranean sea: genetic and palaeoclimatic significance. quaternary international, 5, 1-8. cremaschi m. (1987) loess deposits of the plain of the po and of the adjoining adriatic basin (northern italy). in: pecsi m., french h.m. (eds.), loess and periglacial phenomena. akademiai kiado, budapest, hungatia, 125-140. cremaschi m. (1990) the loess in northern and central italy: a loess basin between the alps and the mediterranean sea. c.n.r., centro di studio per la stratigrafia e petrografia delle alpi centrale, milano, italy, pp. 187. cremaschi m. (2004) late pleistocene loess. in: antonioli f., vai g.b. (eds.), litho-palaeoenvironmental maps of italy during the last two climatic extremes. climex maps italy, museo geologico giovanni cappellini, bologna, italy, 34-37. cremaschi m., zerboni a. (2016) la questione dell’apparato morenico del garda alla luce delle recenti ricerche sul torrion della val sorda. geologia insubrica, 12/1, 103. cremaschi m., zerboni a., nicosia c., negrino f., rodnight h., spötl c. (2015) age, soil-forming processes, and archaeology of the loess deposits at the apennine margin of the po plain (northern italy): new insights from the ghiardo area. quaternary international, 376, 173-188. ferraro f. (2009) age, sedimentation, and soil formation in the val sorda loess sequence, northern italy. quaternary international, 204, 54-64. frigerio c., bonadeo l., zerboni a., livio f., ferrario m.f., fioraso g., irace a., brunamonte f., michetti a.m. (2017) first evidence for late pleistocene to holocene earthquake surface faulting in the eastern monferrato arc (northern italy): geology, pedostratigraphy and structural study of the pecetto di valenza site. quaternary international, 451, 143164. haase d., fink j., haase g., ruske r., pécsi m., richter h., altermann m., jager k.d. (2007) loess in europe its spatial distribution based on a european loess map, scale 1:2,500,000. quaternary science reviews, 26, 1301-1312. lindner h., lehmkuhl f., zeeden c. (2017) spatial loess distribution in the eastern carpathian basin: a novel approach based on geoscientific maps and data. journal of maps, 13, 173-181. mapping the po plain loess basin livio f., berlusconi a., zerboni a., trombino l., sileo g., michetti a.m., rodnight h., spötl c. (2014) progressive offset and surface deformation along a seismogenic blind thrust in the po plain foredeep (southern alps, northern italy). journal of geophysical research: solid earth, 119, 7701-7721. orombelli g. (1990) loess in italy: an introduction. in: cremaschi, m. (ed.), the loess in northern and central italy: a loess basin between the alps and the mediterranean sea. c.n.r., centro di studio per la stratigrafia e petrografia delle alpi centrale, milano, italy, 11-12. pye k. (1995) the nature, origin and accumulation of loess. quaternary science reviews, 14, 653-667. rellini i., trombino l., firpo m., rossi p.m. (2009) extending westward the loess basin between the alps and the mediterranean region: micromorphological and mineralogical evidences from the slope of the ligurian alps (northern italy). geografia fisica e dinamica quaternaria, 32, 103116. smalley i.j., leach a.j. (1978) the origin and distribution of the loess in the danube basin and associated regions of east-central europe a review. sedimentary geology, 21, 1-26. vai g.b., cantelli l. (2004) litho-palaeoenvironmental maps of italy during the last two climatic extremes, map 1 last glacial maximum, map 2 holocene climatic optimum, 1:1,000,000 scale, 32nd igc florence 2004, museo geologico giovanni cappellini, bologna. wacha l., pavlakovic s.m., novothny a., crnjakovic m., frechen m. (2011) luminescence dating of upper pleistocene loess from the island of susak in croatia. quaternary international, 234, 50-61. zerboni a., trombino l., frigerio c., livio f., berlusconi a., michetti a.m., rodnight h., spötl c. (2015) the loess-paleosol sequence at monte netto: a record of climate change in the upper pleistocene of the central po plain, northern italy. journal of soils and sediments, 15, 1329-1350. 256 zerboni a. et al. ms. received: may 4, 2018 final text received: may 14, 2018 amq abs bartolinilucenti rook saccom 169-172.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 169 172 the fossil record of the genus canis (canidae, carnivora, mammalia) from the upper valdarno: a critical revision in the frame of the early and middle pleistocene canids of eurasia saverio bartolini lucenti1,2, lorenzo rook2 1 dottorato di ricerca in scienze della terra, università di pisa, pisa, italy 2 dipartimento di scienze della terra, università degli studi di firenze, firenze, italy corresponding author: s. bartolini lucenti <saverio.bartolini@dst.unipi.it> abstract: the outstanding fossil record of the upper valdarno basin is renown since the xv century. its early pleistocene sample of canids, characterized by the large sized lycaon falconeri and the medium-sized canis arnensis and canis etruscus, has laid the basis for the study of the evolution of the genus canis in western eurasia. in recent years, several discoveries tend to modify our conception on this subject, e.g. the lineage that leads to modern wolves or the inter/intraspecific variability of fossil species, but the record of uv basin remains one of the most extensive and important of its age. keywords: upper valdarno, pleistocene, canidae, taxonomy, evolution 1. introduction in the international panorama of continental quaternary sites, the upper valdarno basin is historically renowned from the renaissance for its outstanding record of large mammals (rook et al., 2013), and since the 18th century naturalists and early palaeontologists, above all g. cuvier (cuvier, 1812; 1821-1824), have studied the mammals recovered from this basin (cioppi & dominici, 2010). for the scholars who study the family canidae, the significance of this basin emerged by the end of the 19th and the beginning of the 20th century (forsyth major, 1877; del campana, 1913) with the description of the medium-sized canis arnensis del campana, 1913 and the large lycaon falconeri (forsyth major, 1877). these two species, together with canis etruscus forsyth major, 1877 also recovered from the other tuscan locality of olivola, represented the earliest species of the genus to be described in western eurasia. the faunal assemblage of these localities suggested a correlation to the beginning of the calabrian (i.e., at that time, the plio-pleistocene boundary) (azzaroli, 1977), as confirmed by some magnetostratigraphic calibrations (e.g. napoleone et al., 2003). the appearance of canis etruscus came to be known as the “wolf event” (azzaroli, 1983; azzaroli et al., 1988; rook & torre, 1996). other findings, e.g. those of coste san giacomo (2.1 ma, bellucci et al., 2012) and vialette (disputed 3 ma, lacombat et al., 2008), have shown the diachronic state of the arrival of canis taxa in europe (sotnikova & rook, 2010 for further discussion). nevertheless, the record of canis the upper valdarno still has to be regarded with great interest by international researchers for the implication its fossil have. for instance, c. etruscus is generally considered as the ancestor of the lineage that leads to the modern wolf (sotnikova, 2001; brugal & boudadi-maligne, 2011). moreover, several sites across eurasia indicate the occurrence of c. etruscus-like canids (see cherin et al., 2014 and reference therein). on the contrary, c. arnensis seems limited to sites of “tasso fu” faunal components (torre et al., 1992). interestingly, the former argued that this species could be the european representative of a holoarctic coyote-like population, with canis lepophagus as american correspondent. during the early pleistocene the diversity of species of canis is not limited to these two as canis senezensis martin, 1973 was described from senèze (massif central, france; ca. 2 ma) whereas in spain, canis accitanus garrido & arribas, 2008 is reported from fonelas p-1 (guadix basin, granada ca. 1.9-1.7 ma). around 1.5-1.4 the first representatives of canis mosbachensis soergel, 1925 appears in spain and in italy. lastly, from the site of apollonia comes the disputed canis apollonensis koufos & kostopoulos, 1997. this variability of species decreases around the epivillafranchian (ca 1 ma) as only c. mosbachensis remained in western europe (sotnikova & rook, 2010). in asia, the pattern of decrease in diversity is similar. during the early pleistocene several medium to large-sized species were present [canis chihliensis zdansky, 1924 and canis palmidens (teilhard de chardin & piveteau, 1930) from nihewan basin; canis teilhardi qiu et al., 2004, canis longdanensis qiu et al., 2004 and canis brevicephalus qiu et al., 2004 from longdan] but in the middle pleistocene the mediumsized and mesocarnivorous niche of canids was occupied by c. mosbachensis variabilis pei, 1934 (jiangzuo et al., 2018). this short review aims to resume past knowledge in the light of recent discoveries with unpublished material that has significant implications for the phylogeny of this group of carnivora. https://doi.org/10.26382/aiqua.2018.aiquaconference 2. material and methods the material considered for the present research is housed at the museum of natural history of the university of florence. comparative fossil and extant sample studied comes from various european sites (fig. 1) and it is held in different european and north american institution as the montevarchi paleontological museum; la specola zoology section of the museum of natural history of the university of florence; the american museum of natural history (new york); the georgian national museum (tbilisi); the aristotle university of thessaloniki; the hungarian museum of natural history and the geological society of hungary (budapest); earth science department of the université claude bernard lyon-1. furthermore all the relevant literature on fossil canis has been reviewed. the morphometric analyses used in this study include log ratio diagrams (simpson, 1941), box plots, and biplots. those analyses were performed with past ver. 3.14 (hammer, 2016). the measurements where taken to nearest of 0.1 mm following driesch (1976). 3. results the morphometric and morphological comparison of the tuscan material of c. etruscus and that of c. etruscus from dmanisi showed important difference both in dental proportions and, more importantly, in cranial features e.g., the elongation of the skull in rostrocaudal sense; the length of the nasal (fig. 2); the height of the skull; the anteroposterior divergence of the medial wall of the tympanic bullae. the morphology of these characteristics in c. “etruscus” from dmanisi are more similar to the other early pleistocene canid c. mosbachensis as well as to extant and more derived species e.g. c. lupus rather to the coeval c. etruscus or c. arnensis. similar characteristics have been recognized in the sample of gerakarou (greece). although the size is intermediate between c. arnensis and c. etruscus, the greek specimens show the same morphologies that characterize the material of canis sp. from dmanisi. the analyses on several samples taxa from early and middle pleistocene sites across europe such as venta micena, pirro nord, apollonia, petralona, vértesszȍlȍs ii (fig. 1) have revealed a wide range of variability in size but a general morphology shared by all these samples, all referable to c. mosbachensis-like canids. 4. discussion and conclusions the fossils of c. arnensis and c. etruscus of the olivola and tasso fu represent one of the most extensive record of the genus canis of the early quaternary and among the earliest record in western europe. these samples remain pivotal basis for comparison in the attempt to resolve the intricate scenario of early pleistocene canids across eurasia. the morphometric and morphological characteristics found in the georgian canis “etruscus” greatly contrast with the peculiarities of c. etruscus. moreover, the canis from dmanisi presents several cranial affinities to eurasian c. mosbachensis and to other modern wolf-related species, for instance the antero-posteriorly divergent medial walls of the tympanic bullae, as also noticed by sotnikova & rook (2010). relevance of this feature stands in the fact that 170 bartolini lucenti s., rook l. fig. 1 geographic localization of the sites considered in this study. 1, venta micena, spain; 2, cueva victoria, spain; 3, vallparadís estació-cal guardiola, spain; 4, olivola, italy; 5, upper valdarno, italy; 6, pirro nord, italy; 7, gerakarou, apollonia-1, petralona, greece; 8, dmanisi, georgia; 9, vértesszȍlȍs ii, hungary. only some extant species but no fossil taxa present it, with the exception of c. mosbachensis (bartolini lucenti et al., 2017; jianzuo et al., 2018). altogether this evidence leads us to consider this taxon as canis sp. nov. the new information on the dmanisi canis sp. has strong implications on the evolutionary history of the late villafranchian canids, because it changes the widely accepted c. etruscus-c. mosbachensis-c. lupus lineage. although the status of c. mosbachensis is questioned by some authors (for an updated resume see mecozzi et al., 2017), the slight morphological differences found in samples of early to middle pleistocene sites attributed to c. mosbachensis-like canids should definitely be regarded as results of the intraspecific variability. surely, such little variations are not sufficient to erect new species. likewise, it would be misleading to interpret this diversity as part of the variability of the modern c. lupus. in this sense, the ascription of the chinese taxon c. variabilis as a subspecies of c. mosbachensis in jiangzou et al. (2018) offers an interesting solution to the issue. acknowledgements the authors are thankful to all the curator of the institutions visited for granting us access to the collection in order to study the variability of early-middle pleistocene: cioppi e.(igf), rustioni m. (mpm), agnelli p. (mzuf), galkin j., meng j. (amnh), lordkipanidze d., bukhsianidze m. (gnm), koufos g. (aut), gasparik m. (hmnh), robert e. (ucbl), berthet d. (mdc). references azzaroli a. (1977) the villafranchian stage in italy and the plio-pleistocene boundary. giornale di geologia, 41, 61-79. azzaroli a. (1983) quaternary mammals and the endvillafranchian dispersal event a turning point in the history of eurasia. palaeogeography, palaeoecology, palaeoclimatology, 44, 117-139. azzaroli a., de giuli c., ficcarelli g., torre d. 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(2014) redefining canis etruscus (canidae, mammalia): a 171 canis of the upper valdarno: revision in the eurasian framework fig. 2 boxplot resuming the variability of the ratio gnl/tl (greatest nasal length/total length of the cranium) in early pleistocene taxa (as c. etruscus, c. arnensis, c. mosbanchesis, and canis sp. from dmanisi) and in extant species of the genus canis. new look into the evolutionary history of early pleistocene dogs resulting from the outstanding fossil record from pantalla (italy). journal mammalian evolution, 21, 95-110. cioppi e., dominici s. (2010) origin and development of the geological and palaeontological collections. in: monechi s. & rook l. (eds.), il museo di storia naturale dell’università di firenze. le collezioni geologiche e paleontologiche, 3, 19-55. cuvier g. 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(ed.), das pleistozän von untermassfeld bei meiningen (thüringen), teil. 2. habelt verlag, bonn, 607-632. sotnikova m.v., rook l. (2010) dispersal of the canini (mammalia, canidae: caninae) across eurasia during the late miocene to early pleistocene. quaternary international, 212, 86-97. simpson g.g. (1941) large pleistocene felines of north america. american museum novitates, 1136, 1-27. teilhard de chardin p., piveteau j. (1930) les mammiféres fossiles de nihewan (chine). annales de paleontologie, 19, 1-134. torre d. (1967) i cani villafranchiani della toscana. paleontographia italica, lxiii, 113-138. torre d., ficcarelli g., masini f., rook l., sala b. (1992) mammal dispersal events in the early pleistocene of western europe. courier forschungsinstitut senckenberg, 153, 51-58. zdansky o. (1924) jungtertiare carnivoren chinas. palaeontologia sinica, new series c, geological survey of china. pp. 223. 172 bartolini lucenti s., rook l. ms. received: may 6, 2018 final text received: may 26, 2018 sess 1_160211.pub il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 vertical mobility of the continental margin between latium and tuscany defined by means of eustatic minimum indicators francesco latino chiocci1,2, serena fraccascia1,3, davide scrocca2, francesco falese1 1university of rome “la sapienza”, rome, italy 2national research council, institute of environmental geology and geoengineering, rome, italy 3current affiliation: university of bremen, bremen, germany corresponding author: f. l. chiocci <francesco.chiocci@uniroma1.it> abstract: chiocci f. l. et al., vertical mobility of the continental margin between latium and tuscany, defined by means of eustatic minimum indicators (it issn 0349-3356, 2011) a number of earlier coastal tectonic studies used marine terraces and their correlation with the eustatic curve in order to define vertical movements (uplift or subsidence) of coastal areas. analogamente, in this study the paleo-shelfbreak formed at the sea level lowstand of mis 12 (450 kyr) and two submerged terraced related to it were characterized by analyzing high resolution reflection seismic profiles. their current depth below the present day sea level were measured and compared to the sea level of mis 12, as know from literature. these features are currently located at different depths along the continental margin, due to the interaction between load subsidence of the margin (at a rate of 0.20 mm yr-1 in the last 450 kyr) and tectonic uplift (at a rate up to 0.20-0.24 mm yr-1, varying along the margin). riassunto. chiocci f. l. et al., mobilità verticale del margine continentale al confine tra lazio e toscana, definite attraverso indicatori di minimo eustatico (it issn 0349-3356, 2011) molti studi di tettonica costiera utilizzano i terrazzi marini e la loro correlazione con la curva eustatica per definire le variazioni verticali (sollevamento o subsidenza) delle aree costiere. analogamente, in questo studio il paleociglio di scarpata formatosi in corrispondenza del basso stazionamento del livello marino del mis 12 (450 ka) e due terrazzi sommersi ad esso correlati sono stati caratterizzati attraverso l’analisi di profili di sismica a riflessione ad alta risoluzione e le loro profondità al di sotto del livello del mare attuale sono state confrontate con il livello marino del mis 12 noto in letteratura. tali elementi si trovano attualmente a profondità variabili lungo il margine continentale, a causa dell’interazione di subsidenza del margine, con un tasso di circa 0.20 mm a-1 negli ultimi 450 ka, e sollevamento tettonico, con un tasso variabile lungo il margine e fino a 0.20-0.24 mm a-1. key words: neotectonics, last glacial maximum, seismic stratigrafy parole chiave: neotettonica, ultimo pleniglaciale, stratigrafia sismica global sea level has changed several times during the geological history. during quaternary, glacio-eustatic sea level changes have been characterized by high amplitude and high frequency (~100 m in 100 kyr) and by a nearly constant range between 120 m depth and the present sea level. in the course of these oscillations, at still-stand stages, terrace-shaped depositional bodies may be formed below the wave base level, resulting from sediment remobilization due to littoral erosion during high-energy storm events (chiocci & orlando, 1996; chiocci et al., 2004). the highstand features are the so-called marine terraces (at the present time occurring along the coasts), whilst lowstand features are wedged-bodies addressed as submerged or lowstand terraces that currently can be found at shelf breaks or, less frequently, in continental shelves (cf. fig. 2 in chiocci et al., 2004). if deposits building up a continental margin are preserved, a sharp change in slope in stratigraphic units can be usually recognised in seismic profiles, which is commonly interpreted as paleo-shelfbreak. as the current shelfbreak is thought to be related to the minimum sea level reached during the last eustatic cycle, paleo-shelfbreaks can be assumed as paleosea level indicators at glacial maximum stages. a paleoshelfbreak usually matches a limit between an erosional unconformity landward and a correlative conformity basinward, which can be used to define the position of eustatic minimum. when sea level changes occur, the aforementioned features may be preserved at their original position, thus becoming sea level proxies. when a coastal region is affected by tectonics, however, the position of marine and submerged terraces can be shifted either upward or downward, if respectively tectonic uplift or subsidence occurs. on land and onshore, the use of marine terraces as proxy of sea level highstand is a well established methodology, with worldwide applications in coastal tectonic studies, in order to assess the vertical mobility of a continental margin (amongst many others, campbell, 1986; marquardt et al., 2004; litchfield et al., 2010). for instance, when dating is not possible, a constant uplift rate is commonly assumed and different terrace orders are correlated to different highstand events from lower younger terraces to higher older ones (e.g. mcneill & collier, 2004). offshore, however, submerged terraces are not as much exploited. high resolution reflection seismics allows a very good depiction of the shallow features and overall stratigraphic architecture of a continental margin, providing a much higher resolution and spatial continuity than geological surveys on land. nevertheless, to the knowledge of the authors, earlier studies dealing with submerged terraces focused on the reconstruction of local sea level lowstands (e.g. shipp et al., 1991, lericolais et al., 2009), while only lebesbye & vorren (1996) investigated these features in order to assess vertical movements due to tectonic subsidence in the barents sea. 26 28 27 here, the paleo-shelfbreak and two submerged terraces created during a middle-upper pleistocene glacial maximum were characterized, in order to define the vertical motions of the continental margin between latium and tuscany. in fact, seismic and sequence stratigraphy, integrated with core ground-truthing and biostratigraphic analysis, allowed to date depositional features related to sea level lowstand of different eustatic cycles. consequently, it was possible to reconstruct uplift/subsidence distribution along the margin. along the continental margin between latium and tuscany (central eastern tyrrhenian sea), about 3000 km of high and very resolution reflection seismic profiles, acquired during the last decades, were analyzed and interpreted by applying principles of seismic and sequence stratigraphy. six seismic units were defined, related to the last ~500 kyr and interpreted as 4th-order depositional sequences. sequence boundaries can be either erosional unconformities or correlative conformities related to unconformities eroded by continental shelf emersion during sea level lowstands. biostratigraphic constraints provided by borehole-logs and gravity cores and correlation with the eustatic curve allowed to establish the chronostratigraphy of sequence boundaries (chiocci, 2000). each sequence boundary was named referring to the lowstand marine isotope stage (mis) when they were thought to be formed. thus, the depositional sequences described in the area are delimited, from the oldest to the most recent one, by the surfaces u14 (540 kyr), u12 (450 kyr), u10 (350 kyr), u8 (260 kyr), u6 (140 kyr) and u2 (20 kyr). landwards of paleo -shelfbreak, sequence boundaries are regional highamplitude reflectors, which erosionally truncate underlying reflectors; basinward, they are high-amplitude highcontinuity reflectors conformably lying on underlying strata. load subsidence usually affecting passive continental margins allowed depositional sequences to be partially preserved even in the inner continental shelf, despite the nearly constant oscillation range of sea level during quaternary. however, in the study area, the sequence boundaries of mis 10, 8 and 6 lack unconformities and show only correlative conformities, while more ancient sequences (e.g. resting on u14 and u12) show both unconformities and correlative conformities, like the u2, related to the last glacial maximum (chiocci, 2000). two buried wedge-bodies were identified in the offshore between tarquinia and ladispoli, the first one ~18 km long and the second one ~27 km long (fig.). they were interpreted as submerged terraces owing to the glacioeustatic minimum of mis 12. the paleo-shelfbreak and submerged terraces of mis 12 were analyzed and their characters and depth were defined along the studied margin. based on the assumption that both features were generated at the same sub-sea level depth, they were considered as paleo-sea level indicators. the depth of paleo-shelfbreak and submerged terraces (inner edge) below the current sea level gradually changes along the margin, rising from an average of 220 m in the northern sector (mt. argentario) to 131 m offshore civitavecchia and ladispoli, then decreasing to 202 m athwart tiber river mouth and rising again to 166 m offshore lido di ostia (fig.). the northern sector of the study area, where metamorphic bedrock arises, was considered to be stable, so that current depth of mis 12 paleo-sea level indicators is only affected by subsidence. therefore all paleo-sea level indicators found at lower depth are supposed to have been uplifted. assuming that during mis 12 the sea level was about 130 m below the current sea level (pisias et al., 1990, cited by caputo, 2007), the overall subsidence of the outer continental shelf was estimated in about 0.20 mm yr-1 in the last 450 kyr. considerations about the differential preservation of depositional sequences in the study area suggests that the regional uplift occurring in the continental margin began between 450 and 350 kyr, when the surfaces u12 and u10 developed, respectively. the depth of mis12 paleoshelfbreak and related depositional terrace gradually decreases south-eastward, moving along the margin, implying a relative uplift of about 89 m with respect to expected depth of 220 m (fig. 1). taking the latter as a reference value, a differential uplift rate up to 0.20 or 0.25 mm yr-1 can be estimated for the civitavecchia-ladispoli offshore, respectively in the last 450 kyr or 350 kyr. in agreement with this result, the lack of unconformity of mis 6, 8 and 10 and the preservation only in outer shelf of the older ones, indicates that uplift must have surmounted the regional subsidence that characterizes the tyrrhenian margin. the minimum depth observed offshore civitavecchialadispoli matches with the maximum regional uplift recognized along the coast of latium by on land studies, based on the altitude of uplifted marine terraces related to mis 9, 7 and 5e (340, 250 and 125 kyr respectively) (de rita et al., 2002; nisi et al., 2003; ferranti et al., 2006). studies of coastal terraces reveal that uplift rate increases southeastward and started between 400 and 200 kyr; both this fact point out that uplift may be due to the volcanic activity that affected the margin since 500 kyr (e.g. cavinato et al., 1992; karner et al., 2001; giordano et al., 2003; ferranti et al., 2006). the result of our analysis and their comparison with data derived from the present day elevation of marine terraces suggest that the areal distribution of this uplift is not homogeneous along the continental margin. the overall licture highlight the likely presence of a bulge likely centered on the sabatini mounts volcanic complex, perfectly aligned with the main measured peak. however, seismostratigraphic analysis made by bartole (1995) highlighted the presence of a magmatic intrusion beneath the shelf in this area, independent from the volcanic complexes on land, which may be responsible for the observed uplift. the secondary peak in the mis 12 paleo-sea level elevation (centered to lido di ostia) can be attributed to a local uplift caused by three anticlines whose end of activity is unknown, because the erosion unconformity formed during the last glacial sea-level lowstand eroded most of the depositional sequences more recent than 450 kyr ago. very high-resolution seismic reflection data in this area reveal deformation evidences at least up to 350 kyr. vertical mobility of the continental margin between ... 28 ms. received: testo ricevuto il references bartole r. 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(1991) seismicstratigraphic and geomorphic evidence for a postglacial sealevel lowstand in the northern gulf of maine: journal of coastal research, 7, 341-364. fig. 1, study area and data location. the plot shows the elevation of mis 12 paleo-sea level indicators below current sea level along the transect a-h. area di studio. il diagramma mostra le quote attuali degli indicatori del paleolivello del mare durante il mis 12 lungo il profilo a-h. f.l. chiocci et al. january 15, 2011 15 gennaio 2011 amq abs rossato et al tepro 239-242.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, abstracts, aiqa 13-14/06/2018 florence, 239 242 post-lgm catastrophic landslides in the dolomites: when, where and why sandro rossato1, silvana martin1, susan ivy-ochs2, alfio viganò3, christof vockenhuber2, manuel rigo1, nicola surian1, paolo mozzi1 1 university of padova department of geosciences, padova, italy 2 laboratory of ion beam physics, eth-honggerberg, zürich, switzerland 3 servizio geologico della provincia autonoma di trento, trento, italy corresponding author: s. rossato <sandro.rossato@unipd.it> abstract: this paper aims to present the state-of-the-art about large and catastrophic landslides that have occurred in the dolomites since the last glacial maximum (lgm). such events have been proved to happen multiple times in the same area, in correspondence of prolonged rainfall events, ice/snow melting and seismic shakings. predisposing factors, such as rock fracturation and vertical bedding strata, may accumulate rock fatigue and induce the formation/weathering of shear planes, weakening the rock mass and allowing lowmagnitude events to trigger the movement. keywords: cosmogenic 36cl, geological risk and hazard, geomorphic hazard, dolomites 1. introduction landslides are phenomena that can deeply affect both natural and anthropogenic landscapes, and they can represent a serious risk (e.g. petley, 2012). understanding their predisposing factors and potential triggers is of utmost importance to reduce their potential impacts, especially in the alps where narrow valleys are increasingly inhabited (e.g. huggel et al., 2012). in the last three decades, it has been estimated that the costliest natural event occurred in italy was the notorious val pola rock avalanche, occurred on 28th july 1987. it has been estimated that the total amount of damages reached us$ 400 million (crosta et al., 2004). in the alps, the largest landslides were presumed to have occurred during the latest phases of the last glacial maximum (lgm), or within a few millennia after deglaciation as a response to glacial unloading of valley slopes. recently, some of them, such as “lavini di marco”, (martin et al., 2014), “marocche di dro” (ivyochs et al., 2017a), “castelpietra” (ivy-ochs et al., 2017b) and “mt. peron” (rossato et al., submitted), have been isotopically dated, proving to be holocene in age, thus suggesting that such large events may occur without major changes in the equilibrium of the slopes. in the dolomites several landslides occurred, such as the fadalto, antelao and vajont events, causing damages and casualties, even when the moving masses were small. the vajont event hit the headlines all over europe for its disruptiveness, being the most catastrophic events in the study area, but other large landslides occurred in the past. here we summarize the largest and most catastrophic landslides in the dolomites, focusing on their type, timing and impact on human life/activities, discussing their possible predisposing and triggering factors. we will not discuss deep-seated gravitational slope deformations and creep deformations, since they are characterized by relatively low deformation rates. 2. catastrophic dolomites landslides all landslides occurred in the dolomitic area that are relevant in terms of volume and/or impact on human activities are here presented (tab. 1) and shortly described based on the papers listed. 2.1. alta badia (borgatti & soldati, 2010) numerous events took place near corvara, since 10 ka cal bp to present. earth/mud/debris flows constitute most of the events, along with rotational rock slides. water availability, due to permafrost melting and/or rainfall events, is believed to be the potential trigger for these events and climatic conditions are believed to be the main cause of widespread landsliding. 2.2. alleghe (ermini & casagli, 2003) the alleghe event was a large (10 mm3) translational rock fall, possibly evolved into a rock avalanche. the debris mass reached a runup elevation of about 150 m above the valley bottom, on the opposite flank. a second, smaller (3 mm3) event took place some months after. both events have been linked to the high amount of rain and snow occurred during that winter. 2.3. antelao (montandon, 1933) on 21st april 1814, a large debris mass fall from the mt. antelao, split into two tongues and inundated the localities of taolen and marceana, causing 260 casualties. a temporary lake formed in the boite valley. this event was the most damaging of a sequence of landslides falling at the same place (e.g events are recorded also on 1348, 1729 and 1737 ad). 2.4. col mandro (montandon, 1933) in december 1933, a debris mass, detached from the col mandro, dammed the vanoi valley, forming a temporary lake. this event was the biggest of a sequence of mass movements in the area. it is believed https://doi.org/10.26382/aiqua.2018.aiquaconference that such events were due to deforestation and poor management of irrigation. 2.5. cortina d’ampezzo (borgatti & soldati, 2010) since 14 ka cal bp, in this area several events (earth flows and translational rock slides) have occurred. as for the alta badia case, climate is invoked as the possible driving factor, due to their clustering in specific time intervals. it is noteworthy that a single earthflow was triggered by the 15th september shock of the 1976 friuli earthquake sequence. 2.6. fadalto (pellegrini et al., 2006) this event is a large (135 mm3) and complex landslide involving various types of movements (rock slide, rock avalanche, debris slump, etc). it blocked the whole valley, forming the s. croce lake. the initial trigger is believed to be the relaxation of the slopes owing to glacier retreat, but the main scarp has been repeatedly reactivated since then. 2.7. la valle (montandon, 1933) in april 1701, a “rock avalanche” (this term may not correspond to its modern scientific meaning) detached from the mt. moschesin, causing 48 casualties. other minor events occurred later at the same place. 2.8. marziai (pellegrini et al., 2006) the rocky mass detached from mt. miesna, where rock layers are lightly dipping towards the slope and pervasive foliation is present. the landslide was suggested to have occurred in the first phase of deglaciation (i.e. 17-15 ka cal bp) by means of palynological data obtained from the remains of the temporary lake formed by the landslide itself. as for the fadalto landslide, the reaction of the slopes to glacier retreat is evoked as possible trigger. 2.9. monte salta (marcato et al., 2007) this rock avalanche, which occurred in 1674 ad, is strictly connected to the presence of major faulting, folding and fracturing of the rock mass, that dips steeply towards the slope. such an unstable setting makes the slopes prone to failure and the authors suggested that seismicity may be, or may have been, the trigger. 2.10. pecol (montandon, 1933) this event occurred in 1841 ad, evolved by steps during an entire week, causing various casualties and destroying an entire part of the village of pecol. 2.11. mt. peron (rossato et al., submitted) this enormous rock avalanche (170 mm3) fell from the top of mt peron and spread in the area where the villages of peron, ponte mas, vignole and roe are currently located. the event was believed to be lateglacial in age, but recent cosmogenic dates and historical data proved that it occurred during the roman era, prior to the 2nd century ad. 2.12. siror (montandon, 1933) this event was one of the many mass movements related to the occurrence of an earthquake on 25th january 1348. it detached from mt. belvedere and destroyed 240 table 1 summary table of the largest and most damaging (in terms of human lives) landslides in the dolomites. rossato s. et al. 241 the village of pubiaco, causing tens of casualties. 2.13. vajont (borgatti et al., 2004) the infamous, and extremely large, vajont event was due to the reactivation of an old landslide, after nearly three years of progressive creeping. on 9th october 1963, 270 mm3 of debris and rock mass fell into an artificial reservoir, forming a flood wave that wiped out the village of longarone, causing nearly 2000 casualties. 2.14. val cia (montandon, 1933) the rocky mass detached from the left flank of the cia valley in the 1882 ad, blocked the valley, and formed a temporary lake that breached soon after. the resulting flood, 4 mm3 large, affected the whole valley and propagated down to the vanoi valley. 2.15. valle san lucano (aldighieri et al., 2016) on 3rd december 1908 a landslide detached from the fourth pala di san lucano and buried pra and lagunàz villages, causing 28 casualties. unstable rock masses are still visible in the main scarp area. 3. predisposing and triggering factors the history of the dolomites documented several landslides that caused damages and casualties, even when the moving masses were small (e.g. valle san lucano). the vajont event hit the headlines all over europe for its disruptiveness, being the most catastrophic events occurred in the study area (borgatti et al., 2004). however, other similar events occurred in the past, but are less known due to their “limited” amount of losses (e.g. antelao) or old age (e.g. mt. peron). in some occasions, such landslides caused a radical change in the landscape, as the alleghe landslide: the debris mass blocked the cordevole river and induced the formation of the alleghe lake. such natural barrier has been artificially stabilized, and the lake is still present (draganits et al., 2014). catastrophic slope failures are often related to the presence of discontinuities in the rock mass, as faults, shear zones and joints (jaboyedoff et al., 2013; stead and wolter, 2015). favorable bedding of strata (e.g. mt. peron) and the presence of relict landslides (e.g. vajont) can concur to reduce the internal strength of the rock mass, contributing to the progressive accumulation of rock fatigue. the lower the energy required to break the equilibrium, the weaker the magnitude of the trigger event and the more probable the occurrence of forerunner events (loew et al., 2017). triggering events may be geological, hydrological, structural or even anthropogenic (cruden and varnes, 1996; wieczorek, 1996). prolonged and intense rainfalls are recognized to initiate movements, along with progressive failure, seismic shaking/volcanic activity, human activity or accelerating creep (keefer, 1993; di crescenzo and santo, 2005; adushkin, 2006; loew et al., 2017). catastrophic events may happen with (e.g. loew et al., 2017), or without a clear trigger or precursory events (e.g. dunning et al., 2006). the dolomites are disposed to earthquake activity, as the instrumental record testifies (up to ~mw=6.5; viganò et al., 2015), and seismicity has been classified as a possible trigger for numerous holocene large landslides in the alps (ivy-ochs et al., 2017a). only one of the considered events has been surely related to an earthquake, but there is a long record of seismicityrelated minor rockfalls and shallow landslides (borgatti & soldati, 2010). conversely, some authors highlighted a good correspondence between large dolomitic landslides (borgatti & soldati, 2010, rossato et al., submitted) and rainfall climatic events/phases occurred at various scales (e.g. tinner and kaltenrieder, 2005; benito et al., 2015; rossato et al., 2015). 4. conclusions as the predisposing factors (rock fracturation, vertical bedding strata, fracture planes cutting the stratigraphic sequence) and triggers (seismicity and/or rainfall events) are often still present after the landslide occur, there is a high likelihood of generating rock failures at the same place that may reach high magnitude. the dolomitic landslide record suggests that no exceptional event is required for large mass movements to happen, the continuing accumulation of predisposing factors lowering the energy needed to trigger them. lowmagnitude shakings, especially in combination with an increase of pore-pressure due to prolonged and intense rainfalls, may be enough to overcome the stability threshold. references adushkin v.v. 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(1996) landslide triggering mechanisms. landslides: investigation and mitigation, 247, 76-90. 242 rossato s. et al. ms. received: may 11, 2018 final text received: may 28, 2018 available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 49 53 birds from the late pleistocene: environmental and climatic scenarios between the alps and the great adriatic plain (north-eastern italy) lisa carrera università degli studi di ferrara, dipartimento di studi umanistici, sezione di preistoria e antropologia, ferrara, italy corresponding author: l. carrera <lisa.carrera@student.unife.it> abstract: in this work we show the potential of bird remains as environmental and climatic proxies, reconstructing the environmental scenarios of the piedmont area of north-eastern italy across the mis3/mis2 boundary, on the basis of the fossil avifauna that we found in rio secco cave (pn) and buso doppio del broion cave (vi) in the berici hills. the results indicate the presence of a mosaic of environments, with open and forested areas and water and rocky habitats in a context of cold climatic conditions as indicated by the finding of the cold-adapted species bubo scandiacus and lagopus muta. keywords: birds, palaeoenvironment, late pleistocene, north-eastern italy, rio secco cave, buso doppio del broion cave 1. introduction western palearctic avifauna consists of more than 500 breeding species, each of which has very specific ecological needs and a strong link with his habitat, particularly with the type of vegetation: this aspect makes fossil avifauna a coherent palaeoenvironmental and palaeoclimatic proxy for the whole pleistocene, as most of extant bird species are reported in the western palearctic since the early pleistocene (tyrberg, 1998, 2008). resident species are more useful than migratory ones for this purpose, as they live in the same habitat during the whole year. fossil birds are also useful to infer past climatic conditions. the pleistocene climatic oscillations have shaped, over the course of time, the range of many species, which followed the shift of their ecological niche. for instance, during cold phases, mediterranean europe represented a “refuge area” for arctic, subarctic and boreal species (e.g. the snowy owl, bubo scandiacus) (holm & svennning, 2014; sanchez marco, 2004). the presence of these species in the fossil record of western palearctic mid-latitudes represents a proxy of a climate colder than present. the fossil record of other bird species, like the rock ptarmigan (lagopus muta), indicates that they were more widespread and lived at lower heights than today during the cold phases, as they followed the descent of the vegetational zones. the finding of these species at low heights in the mid-latitudes, can be used with caution as a climate proxy. we point out that only evidence concerning strong latitudinal or altitudinal changes in the geographic distribution of a bird species should be considered as a climate proxy (bedetti & pavia, 2001; carrera et al., 2018; tyrberg, 2010). we can also infer past climate changes on the basis of the changes in the bird species associations across the layers of a single deposit. this approach can be based, in detail, on the presence of a climate marker in a layer, on changes in the relative abundance of a species, or on variations in the proportion of taxa from different habitats (open, rocky, water, forest) (bedetti & pavia, 2007; tomek et al., 2012). to obtain a representative result, this analysis should be applied to deposits with a high number of bird remains and a long stratigraphic sequence. in this work, we carried out a systematic analysis of the avifaunal remains from the deposits of two palaeolithic sites in north-eastern italy: buso doppio del broion cave (vi) and rio secco cave (pn). in detail, we analysed the avifaunal assemblages coming from the layers referable, from both sites, to the mis3/mis2 boundary, in order to infer past climate and environmental characteristics of this geographic area in a context of increasingly harsher climate (clark et al., 2009; monegato et al., 2017). both sites are located along the connection area between the so-called “great adriatic plain”, the large plain which emerged in the northern adriatic area during the cold phases of the late pleistocene (antonioli, 2012), and the piedmont fringe (fig. 1). the rio secco cave is located on the pradis plateau (eastern carnic pre-alps), at an elevation of 580 m a.s.l. the plateau faces the friulian plain to the south. the late pleistocene sediments cover a time span from 50 to 30 ka, with evidence of short-term gravettian and mousterian occupations. the layer 6, an anthropic layer contained in the macrounit br1, yielded an age of 33,480–30,020 yr cal bp, assessing its placement in the early gravettian period (peresani et al., 2014; talamo et al., 2014). the buso doppio del broion cave is a cavity formed by a system of galleries which opens at 150 m a.s.l. in the eastern slope of the berici hills (an uplifted karst plateau isolated in the https://doi.org/10.26382/aiqua.2018.aiquaconference alluvial plain). the deposits of buso doppio del broion cave, below the upper reworked sediment, contain scanty gravettian lithic implements. the sequence probably covers a time span including the onset of the lgm (layer 1) and the preceding millennia, on the basis of the similarity of the lithic material to a radiocarbon dated palaeolithic site located in the proximity of the cave (gurioli et al., 2006; romandini et al., 2015). the archaeological excavation in these two caves is ongoing, carried out by the university of ferrara. 2. materials and methods the systematic analysis of the avifaunal remains involved 194 avian remains from the macro-units br1 and br2 of rio secco cave, and 775 bird remains from layers 1, 2, 3, 4, 5, 6, 7 of buso doppio del broion cave. the sediments were excavated in 50 × 50 cm or 33 × 33 cm squares and then wet sieved. for the systematic analysis we used two modern bird skeletal comparative collections: the “marco pavia ornithological collection” (mpoc), stored at the dipartimento di scienze della terra of the torino university, and the one held at sezione di scienze preistoriche e antropologiche of the dipartimento di studi umanistici of the university of ferrara. the fossil material is stored in the sezione di scienze preistoriche e antropologiche of the dipartimento di studi umanistici of the university of ferrara. bird taxonomy follows del hoyo et al. (2014, 2016). 3. results we identified a great variety of bird species from the two deposits (tab. 1). the bird taxa recognized in this work all belong to the extant western palearctic avifauna. in the rio secco cave bird assemblage, in detail, we identified 166 remains (85.6 %) which have been assigned to 31 bird taxa (18 species) (carrera et al., 2018). 28 remains are left as indeterminate aves. in the buso doppio del broion bird assemblage, we identified 634 remains (81.8 %) which have been assigned to 69 bird taxa (44 species), while 141 remains are left as indeterminate aves (carrera et al., in press). among the identified remains, for both assemblages, several remains have been attributed to species-level taxa and others to supraspecific taxa, because of their fragmentation or because of the lack of diagnostic features. 4. discussion and conclusion the bird species identified allowed palaeoenvironmental and palaeoclimatic reconstructions. among the bird taxa found at rio secco cave, l. muta and p. collaris suggest the presence of open areas with low vegetation and rocky exposures close to the cave, while p. perdix and c. coturnix indicates the presence of open grasslands/shrublands. l. tetrix, t. urogallus, p. canus, n. caryocatactes, p. pyrrhula and l. curvirostra indicate the presence of conifer or mixed forests, while f. atra suggests the presence of slow-flowing water bodies (cramp, 1998). l. muta is absent today from the area of the site, as it currently lives at higher heights, above the tree line. its presence during the end of mis 3 at about 580 m a.s.l. indicates that mountain open environments had to be located at lower heights, and thus it can be considered an indicator of a climate colder than the current one (carrera et al., 2018). the deposit of buso doppio del broion cave provided a wide range of bird species useful for palaeoenvironmental reconstructions. the presence of open habitats like grasslands, shrublands and steppe is sug 50 fig. 1 map of northern italy with the geographic position of buso doppio del broion cave (a) and rio secco cave (b). the light grey area indicates the extension of the great adriatic plain during the time span investigated. carrera l. 51 tab. 1 bird taxa from the macro-units br1 and br2 of rio secco cave (carrera et al., 2018) and from the layers 1, 2, 3, 4, 5, 6, 7 of buso doppio del broion cave (carrera et al., in press). nr indicates the number of remains for each taxon. fossil birds as a proxy for palaeoenvironmental and palaeoclimatic reconstructions gested by the presence of c. coturnix, p. perdix, g. grus, t. tetrax, a. noctua, b. scandiacus, f. tinnunculus, e. alpestris and cf. p. petronia. other species indicate the presence of rocky cliffs and exposures, such as a. pallidus/apus, a. chrysaetos, p. graculus, p. pyrrhocorax, c. corax, p. rupestris, t. muraria and p. collaris. t. urogallus, l. tetrix, s. ulula, a. funereus, a. gentilis, p. viridis, n. caryocatactes, t. troglodytes, p. pyrrhula and l. curvirostra indicate the presence of conifer or mixed forests. finally, a variety of water bird species such as a. ferina, a. fuligula, s. querquedula, a. platyrhynchos, a. crecca, g. chloropus and g. gallinago, suggests the presence of slow-flowing water bodies, wetlands or marshes near the site (cramp, 1998). the finding of two cold-adapted boreal species, b. scandiacus and s. ulula, both currently absent from the italian avifauna (brichetti & fracasso, 2015), indicates a climate colder than present during the time span investigated. other indications of a climate colder than present is the finding, at low heights of l. tetrix, t. urogallus, p. graculus, p. pyrrhocorax and p. collaris, which currently live, in the alps, in high mountain environments only (carrera et al., in press). the avifaunal assemblages from both the sites provided a coherent environmental framework for the geographic area of connection between the piedmont area and the great adriatic plain, constituted by a mosaic of different habitats. this frame is further supported by the results of the analysis of the pollen records from the fimon lake deposits and the azzano decimo core, in the friulian plain (about 40 km south of rio secco cave) (pini et al., 2009, 2010). during the lgm, the landscape of the piedmont area was constituted by an extensive belt of boreal trees, while the nearby plain was characterized by large steppe habitats, dominated by artemisia and juniper (monegato et al., 2015). despite the richness of the italian palaeornithological record, contributions which deal with avian fossil remains are few with respect to those concerning mammal fossil remains, maybe because of the scarcity of bird skeletal comparative collections. we hope that this field will grow in the near future, as it could provide important advances concerning the palaeobiogeography and palaeoecology of bird species and the evolution of environmental scenarios subjected to the pleistocene climatic oscillations, with the contribution of innovative approaches such as the species distribution modeling (svenning et al., 2011) and phylogenetics. acknowledgements research at the rio secco cave and buso doppio broion cave is coordinated by marco peresani and matteo romandini respectively in the framework of projects supported by the ministry of culture and local institutions and promoters.we are grateful to prof. benedetto sala for his help and precious suggestions, and to ulf johansson (naturhistoriska riksmuseet, stockholm, sweden) for the loan of some crucial recent skeletons. references antonioli f. 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(2018) avian fossil assemblages at the onset of the lgm in the eastern alps: a palaecological contribution from the rio secco cave (italy). comptes rendus palevol, 17, 166-177. carrera l., pavia m., peresani m., romandini m. (in press) late pleistocene fossil birds from buso doppio del broion cave (north-eastern italy): implications for palaeoecology, palaeoenvironment and palaeoclimate. bollettino della società paleontologica italiana. clark p.u., dyke a.s., shakun j.d., carlson a.e., clark j., wohlfarth b., mitrovica j.x., hostetler s.w., mccabe a.m. (2009) the last glacial maximum. science, 325, 710-714. cramp s. (1998) the complete birds of the western palearctic on cd-rom. optimedia. oxford university press. del hoyo j., collar n.j., christie d.a., elliot a., fishpool l.d.c. (2014) illustrated checklist of the birds of the world. vol. 1: non-passerines. lynx éditions, barcelona. del hoyo j., collar n.j., christie d.a., elliott a., fishpool l.d.c., boesman p., kirwan g.m. (2016) illustrated checklist of the birds of the world. vol. 2: passerines. lynx éditions, barcelona. gurioli f., cappato n., de stefani m., tagliacozzo a. (2006) considerazioni paleontologiche, paleoecologiche e archeozoologiche dei livelli del paleolitico superiore del riparo del broion (colli berici, vicenza). in atti del convegno nazionale di archeozoologia, rovereto, 5, 47-56. holm s.r., svenning j.c. (2014) 180,000 years of climate change in europe: avifaunal responses and vegetation implications. plos one, 9(4), e94021. monegato g., ravazzi c., culiberg m., pini r., bavec m., calderoni g., jež j., perego r. (2015) sedimentary evolution and persistence of open forests between the south-eastern alpine fringe and the northern dinarides during the last glacial maximum. palaeogeography, palaeoclimatology, palaeoecology, 436, 23-40. monegato g., scardia g., hajdas i., rizzini f., piccin a. 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(2010) avifaunal responses to warm climate: the message from last interglacial faunas. records of the australian museum, 62(1), 193205. 53 fossil birds as a proxy for palaeoenvironmental and palaeoclimatic reconstructions ms. received: april 29, 2018 final text received: may 19, 2018 54 amq abs spadi saccom 193-197.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 193 197 ostracod assemblages from the palaeolake tiberino (piacenzian-gelasian, central italy): a synthesis marco spadi dipartimento di scienze, università roma tre, roma, italy corresponding author: m. spadi <marco.spadi@uniroma3.it> abstract: this research provides a synthesis of the studies on the non-marine ostracods recovered from the early infillings (piacenzian-gelasian) of the tiberino basin. ostracods were collected from the fosso bianco formation, deposited in a huge and deep lake (palaeolake tiberino), and ponte naja fm. that represents alluvial fan deposits that prograded into the lake. the studied ostracods are referable to 23 species, including 8 endemic species. they group in separate assemblages referable to several ecological niches, suggesting a complex lacustrine environment. this contribution permits to enlarge the dataset of non-marine ostracods distribution in central italy during the plio-pleistocene. keywords: non-marine ostracods, quaternary, ancient lake, palaeoenvironmental reconstruction, tiberino basin 1. introduction the present paper aims to provide an updated overview of the non-marine ostracod data available from the pliocene-early pleistocene deposits of the tiberino basin. in detail, ostracods are used as the main proxy for the palaeoenvironmental reconstruction of the different lacustrine palaeoenvironments. the plio-pleistocene basin-fill succession of the south tiberino basin is around 500 m thick and consists of siliciclastic and carbonate lacustrine and fluvial deposits (fig. 1). the infilling started with the fosso bianco fm. that is composed of clays with associated silty -sand laminae, sedimented in a lacustrine environment. according to basilici (1997), three sedimentological facies associations related to different depositional environments compose this formation: 1) facies association a, which is made up by fine-grained clays and marls deposited in a deep lacustrine setting; 2) facies association b that includes sands and silts corresponding to a gilbert-type delta system prograding into the lake; and 3) facies c that mainly consists of clays deposited in a marshy coastal margin with “taxodiaceae” trunks in life position. the former facies association extensively crops out from todi to san gemini, the facies association b outcrops are limited to the eastern border of the palaeolake (martani mts.) whereas the facies c crops out in the dunarobba fossil forest area (basilici, 1997) (fig. 1). the entire formation is aged late piacenzian-gelasian, based on the magnetostratigraphical, palynological and palaeocarpological analyses (abbazzi et al., 1997; pontini & bertini, 2000; napoleone et al., 2003; martinetto et al., 2014). the ponte naja fm. is composed of finegrained sheet flow deposits with palaeosols, and is probably heteropic to the upper portion of the fosso bianco fm. (basilici, 1995; 1997). according to basilici (1997), the ponte naja fm. is characterised by the facies association d, which consists of clayey silts. it corresponds to the deposition of the distal or middle distal end of an alluvial fan dominated by unchannelized flows and immature palaeosols (basilici, 1995). the large and small mammal remains collected in this unit constrain the age of the formation to the late gelasian (coste san giacomo faunal unit) (abbazzi et al., 1997), between 2.1 and 1.9 ma (bellucci et al., 2014). these two formations are unconformably overlain by the s. maria di ciciliano fm., which is composed of sandy beds and interposed laminated clays deposited in an alluvial plain with dispersed swampy areas, dated to the latest gelasian to calabrian (ambrosetti et al. 1995a; fig. 1 location and geological setting of the study area, with the studied sections, fb: fosso bianco section, dff: dunarobba fossil forest area, and ct: cava toppetti section; modified from basilici (1997). https://doi.org/10.26382/aiqua.2018.aiquaconference basilici, 1997; girotti et al., 2003). finally, along the borders of the tiberino basin crops out the acquasparta formation, dated calabrian or middle pleistocene, made of continental limestones and travertines that were deposited in small shallow lakes (ambrosetti et al., 1995a; basilici 1997). 2. material and methods the freshwater ostracods studied in the tiberino basin were collected from four different section: fosso bianco (thickness 86 m, 19 samples) and cava toppetti i (thickness 107 m; 68 samples) (fosso bianco fm., facies association a), dunarobba fossil forest area, (39 scattered samples) (fosso bianco fm., facies association c), and cava toppetti ii section (thickness 150 m; 68 samples) (ponte naja fm., facies association d) (fig. 1). the frequency matrix of the recovered autochthonous species was analysed with the cluster analysis (morisita distance measure and the unweighted pair group method using arithmetic average upgma). 3. results the autochthonous ostracods recovered in the sedimentological facies association a of the fosso bianco fm. includes 6 species: caspiocypris basilicii, caspiocypris perusia, caspiocypris posteroacuta, caspiocypris tiberina, caspiocypris tuderis and paralimnocythere umbra (spadi et al., 2018). the ostracod fauna recovered in the facies association c of the fosso bianco fm. includes 17 species referable to 12 genera: darwinula stevensoni, vestalenula cylindrica, candona (candona) improvisa, candona (neglecandona) angulata, candona (neglecandona) neglecta, candona (neglecandona) paludinica, candonopsis kingsleii, cyclocypris ovum, ilyocypris bradyi, ilyocypris decipiens, cypris granulata mandelstami, zonocypris membranae quadricella, potamocypris fulva, cyprideis crotonensis, cyprideis rectangularis, all well-known species, as well as two species recovered only in this facies, hemicypris lomastroi and paralimnocythere turgida (spadi et al., submitted). the majority of the samples from the ponte naja fm. are barren or gave only juveniles and/or broken adult valves of different species (allochthonous assemblages) pertaining to both shallow and deep waters; 9 scattered samples bore very few autochthonous species (adults and instars): c. (n.) neglecta, i. bradyi, p. umbra, and c. rectangularis 4. discussion and conclusions the ostracod from the tiberino basin, collected in the sediments associated to the deposition of the palaeolake tiberino (fosso bianco and ponte naja formations) were referable to 13 genera split into 23 species, 8 of which have been recovered only in this palaeolake. most of them were collected in the deep lacustrine (facies a) of the fosso bianco fm. (6 endemic species, five of which pertaining to a caspiocypris species flock) (spadi et al., 2018), while in the swampy lacustrine margin of the facies c of the fosso bianco fm., cropping out in the dunarobba fossil forest area, only 2 exclusive species out of 17 were recovered. the cluster analysis performed in q mode divides the samples bearing different ostracod assemblages into four clusters, suggesting that the lake hosted several different palaeobiotopes hosting diverse ostracod assemblages (figs. 2 and 3). cluster 1 comprises all of the samples from the sedimentological facies association a at fosso bianco and cava toppetti i, characterised by the presence of five caspiocypris species and p. umbra, which are typical of a rather deep lacustrine deposits (spadi et al., 2018). all the recovered caspiocypris of the palaeolake tiberino represent a species flock originated from the local speciation of one pioneer species, since they are more similar each other rather than to other known caspiocypris species of similar age (i.e. the gelasian caspiocypris species flock from the san demetrio synthem, l’aquila basin spadi et al., 2016). the peculiar composition of the endemic ostracod association, characterized only by candonidae and limnocytheridae, together with the presence of endemic molluscs 194 spadi m. fig. 2 dendrogram resulting from the cluster analysis in q-mode (samples) using the upgma method and the morisita similarity applied to the ostracods collected from the dunarobba fossil forest area. the dotted line indicates the similarity level of the separation of the four clusters. samples from: fb: fosso bianco section, dff: dunarobba fossil forest area, and ct: cava toppetti section; pnf: ponte naja fm., modified from spadi et al., submitted. (ciangherotti et al., 1998), indicates that the palaeolake tiberino is a fossil “ancient lake” and that its rather deep lacustrine areas acted as an isolated environment in which endemic speciation was enhanced. cluster 2 includes some samples collected from the dunarobba fossil forest as well as from the cava toppetti ii section. the ostracod assemblage indicates a very shallow lacustrine environment with slow waterbody motions. these samples are also characterised by freshwater prosobranchia-dominated associations (ciangherotti et al., 1998). shallow oxygenated waters rich in nutrients, typical of swampy lacustrine margins characterised by weak waves, is inferred for this welldiversified ostracod and mollusc assemblage. all the samples from ponte naja fm. fall in this cluster, pointing to similar shallow coastal environments into which the alluvial fan prograded. moreover, this finding confirms a similar age between the dunarobba fossil forest deposits and the ponte naja fm. cluster 3 is formed by the samples collected within and directly close to the fossil trunks from the dunarobba fossil forest site. the ostracod assemblage is composed of several species that can withstand permanent/temporary very shallow environments and by c. (c.) improvisa, which is typical of temporary waters (meisch, 2000). the same samples contain molluscs mainly related to terrestrial pulmonate gastropods (ciangherotti et al., 1998). the assemblage indicates a transitional environment between the hydromorphic palaeosols (cluster 4) and swampy lacustrine clays (cluster 2), probably deposited in ephemeral ponds onshore of the lake margin, which, according to ambrosetti et al. (1995b), was seldom occupied by small waterbodies. cluster 4 includes only one sample (tr23-24-25m) from the fossil forest site containing the single ostracod species p. fulva. this species is typical of very shallow aquatic environments with standing waters and has been reported in channels with leaf litter (meisch, 2000). in this sample the molluscs are represented only by terrestrial pulmonate gastropods (ciangherotti et al., 1998). these sediments correspond to a hydromorphic fig. 3 3d reconstruction of the palaeolake tiberino palaeobiotopes in late pliocene-gelasian with occurrence of the related ostracod species. legend: cluster 1: 1 caspiocypris basilicii, 2 caspiocypris perusia, 3 caspiocypris posteroacuta, 4 caspiocypris tiberina, 5 caspiocypris tuderis, 6 paralimnocythere umbra. cluster 2: 7 vestalenula cylindrica; 8 darwinula stevensoni, 9 paralimnocythere turgida sp. nov.; 10 ilyocypris bradyi, 11 candona angulata, 12 zonocypris membranae quadricella, 13 ilyocypris decipiens, 14 cypris mandelstami; 15 cyprideis crotonensis, 16 candona neglecta, 17 candona paludinica, 18 cyprideis rectangularis, 19 hemicypris lomastroi sp. nov. cluster 3: 20 candona improvisa; 21 candonopsis kingsleii; 22 cyclocypris ovum. cluster 4: 23 potamocypris fulva, modified from spadi et al., submitted. 195 ostracod record of palaeolake tiberino palaeosol. in the ostracod assemblages that populated the coastal area of the palaeolake tiberino, most of the species are well-known, although some of them are new records for the italian gelasian or have been collected in italy for the first time. for example, the fossil species c. (n.) paludinica was previously recorded only from the lower and middle paludinian beds (zancleanpiacenzian) of serbia; z. membranae quadricella is a fossil species that is widely distributed in the neogene and quaternary of turkey and the paratethys (mazzini, 2011 with references) but it was recovered in italy only in the upper tortonian deposits of the cessaniti basin (calabria) (ligios et al., 2012); v. cylindrica is known, mainly as fossil, from the neogene and quaternary of europe and turkey (minati et al., 2008 with references) and, in italy, only from the piacenzian (spadi et al., submitted). finally, c. (c.) improvisa is a living species known from the fossil record only since the calabrian, thus, the dunarobba record represents its most ancient occurrence. in a palaeobiogeographical perspective, the presence of c. g. mandelstami, c. (n.) paludinica, z. membranae quadricella and, possibly, h. lomastroi in the coastal sediments of the palaeolake tiberino is remarkable. indeed, their pliocene-gelasian distribution is limited to balkans, paludinian beds (serbia) (krstić, 2006) and eastern europe areas. it is possible to speculate that this ostracod group could have reached the tiberino basin by passive dispersal through aquatic birds shuttling back and forth between both sides of the adriatic sea. in conclusion, the palaeontological and sedimentological information provided by the literature and the present study indicate that during piacenzian–gelasian the tiberino basin hosted a huge (minimum surface of 500 km2) and rather deep (at least 50 m) lake, the palaeolake tiberino (basilici, 1997). the presence in the deep lacustrine environment of a low diversity ostracod association made only of candoninae and leptocytheridae, together with the presence of a caspiocypris species flock lead to consider the palaeolake tiberino as a palaeo-ancient lake (medici & gliozzi, 2008; spadi et al., 2018). the ostracods assemblages from the paleolake tiberino were collected in different lacustrine environments from rather deep lake bottoms (fosso bianco fm, facies a) to several diverse shallow coastal areas (fosso bianco fm., facies c and ponte naja fm.) including swampy lacustrine margins occupied by a “taxodiaceae” forest, and humid areas surrounding the lake (ephemeral ponds and hydrosols). references abbazzi l., albianelli a., ambrosetti p., argenti p., basilici g., bertini a., gentili s., masini f., napoleone g., pontini, m. r. 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(submitted) early pleistocene (gelasian) non-marine ostracods from the dunarobba fossil forest (tiberino basin, umbria, central italy). paper in palaeontology. 197 ostracod record of palaeolake tiberino ms. received: may 6, 2018 final text received: may 18, 2018 198 amq abs fayek et al palcom 125-129.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 125 129 stable isotope stratigraphy of travertine sequences from channel deposits at hierapolis of phrygia (denizli, turkey) asmaa fayek 1, mauro brilli 2, nicolas guyennon 3, francesca giustini 2, mario voltaggio 2 1 geology department, faculty of science, helwan university, cairo, egypt 2 igag, cnr, roma, italy 3 irsa, cnr, roma, italy corresponding author: m. brilli <mauro.brilli@cnr.it> abstract: travertine sequences from petrified channels used in antiquity as water supply canals in the city of hierapolis (denizli, turkey) for irrigation and domestic use were sampled and analyzed for stable isotopes composition. data records from two channels show composite quasi-periodic variations. radium-226 activity was measured to calculate temporal constrains; one of the channels, 182cm thick, deposited in 790±71 years, whereas the other, 644cm thick, in 995±71 years. isotope data, studied through spectral and cross-spectral analysis, indicate that the different oscillation frequencies may be related to surface temperature and rainfall pulses. keywords: isotope stratigraphy, petrified channels, hierapolis of phrygia 1. introduction aerial views and satellite images are definitely the best point to understand how the urban and suburban landscape of hierapolis of phrygia is strongly characterized by the presence of travertine channels (scardozzi, 2013); the dense network that they draw in some areas of the city and outside had already been perceived as an element connoting the topography of the place by the scholars who visited the remains of the city in the nineteenth century and represented it schematically in maps and some views (e.g., trémaux, 1958). the travertine channels of hierapolis originate from thermal springs on the terrace on which the city was founded. they consist of continuous calcareous deposit which has grown over the centuries, often reaching impressive forms today (hancock et al., 2000; özkul et al., 2002). the complex network of travertine channels is divided into two distinct groups from the topographic and chronological point of view (di taranto, 2015). the remains of those canals that descend from the city's terrace towards the fields of the underlying lykos valley can be referred to the oldest group; these channels had the dual function of irrigation and delimitation of agricultural land. they are still preserved today for long distances and with remarkable heights (up to 10 m). the exact location of the springs that fed these canals is not known, but it is possible that they could be found along the edge of the terrace. the most recent group, datable to the middlebyzantine period, is constituted of a network of travertine channels developed within the urban area. the archaeological excavations have confirmed its use between the mid-seventh century ad and about the 1354 ad when an earthquake caused the definitive abandonment of the city. from the urban area the waters flowed towards the valley, partly exploiting the oldest conduits, thus contributing to increase the carbonate accretion, which generated, in the course of the following centuries, the monumental canals we see today. travertine channels are highly interesting constructions, since they are related to human activity. these deposits are often linked to thermal springs. their formation is a consequence of the thermal shock induced by the differences between water and air temperatures that accelerate dissolved carbonate precipitation, producing huge bodies. the kinetics of this cooling are a function firstly of thermal water/air contrast, and secondly of the distance from the spring. jimenez et al. (2006) isotopically studied this peculiar travertine deposits at alicùn de las torres (granada, spain) where active channels are still growing. in the present study, two channels were selected for isotope stratigraphy. their rapid accretion allows evaluation of climatic variations at decadal scale resolution. 2. materials and methods two travertine channels (b and c) were sampled continuously along the central axis of their vertical section where cut surfaces are exposed (fig. 1); before the sampling, a carbonate layer, a few centimeters thick, was scraped to eliminate the external surface exposed to the atmosphere. channel b is located inside the urban area at about 300m away from the closest spring orifice, with a height of 183cm. on contrast, travertine channel c is situated on the steep slopes in the north west side of hierapolis. this channel has grown as high as around 10m; it was sampled for 644cm from the top. oxygen and carbon isotopes measurements were performed on a total of 655 samples from channel b and 182 samples from channel c by using acid digestion technique (gasbench ii (thermo) on line with a delta plus mass spectrometer). results were expressed in delta per mill versus v-pdb standard. https://doi.org/10.26382/aiqua.2018.aiquaconference the sequences were temporally constrained by the dating method based on the decay of radium-226; the details of this method are described by romano et al. (1987). 3. results and discussion dating archaeological information provided some constraints to the time of deposition of the travertine channel bodies. the upper temporal limit of the activity of the channels can be placed around 1354 ad, when a strong earthquake caused the destruction of hierapolis. channel b rests on a pavement of the vii century, whereas the bottom of channel c surely dates back to the roman imperial times (di taranto, 2015). 226ra dating method allows the definition of a time interval between two points selected within the sequence. analyses for 226ra 230th, 232th and 238u activities were run on two samples from channel b (at the top and bottom of the sequence), and on three samples from channel c (at the top, bottom and 380cm from the bottom). formulation of the equations for 226ra method is based on the widely used u-th methods with the further introduction of 230th to 226ra decay. two sources contribute to the activity of 226ra: (i) 226ra originally deposited in the calcite, and (ii) 226ra in equilibrium with 230th, leached from silicatic residue during acid attack (noncarbonatic 226ra). the difference between the total 226ra activity, measured in our samples, and noncarbonatic 226ra activity gives the 226ra excess. the initial activity of 226ra is not known, but assuming it remained constant during the deposition of the travertine sequence it is possible to have the age difference at different levels. the following equation was used to estimate the age difference from 226raexcess ratio between two samples collected at different levels of the sequences: 126 fig. 1 petrified channels at hierapolis. a) panoramic view; b) cut surface along channel c (the bar is 3 m long); c) channel b is the main collector which runs nw – se through the ancient city of hierapolis. fayek a. et al. where 226raexcess (t) is the excess of radium at time t, 226raexcess (o) is the initial activity of 226ra, λ is the 226ra decay constant. the difference between this equation at time t1 and the same equation a time t2, which represent two levels of the sequence, gives the equation of age difference (∆t): 226raexcess is calculated from the difference 226ra 230th, assuming secular equilibrium between 230th and 226ra 127 in the non-carbonatic component. in table 1 are listed the results of the spectrometric analysis and the ∆t calculated in channels b and c. stable isotopes isotope records were converted from data versus thickness to data versus time using the results given by the radium-226 chronology (fig. 2 and b). the relative time vector (t*) associated to the δ18o and δ13c series has been obtained using a linear piecewise interpolation of available durations, under the hypothesis of constant rate of deposition, and setting to 0 the top of the sequences. on initial consideration, the records b and c show low amplitude, composite cyclic variations for both carbon and oxygen records. the main issue is to decipher the various, competing factors that drive oxygen and carbon isotope variations, in order to recover unambiguous paleoclimatic signals. δ18o of travertine calcite reflects the temperature and δ18o of the water where calcite deposited. the δ18o of the water may have been varied in the past for different reasons, namely variation in δ18o of meteoric precipitation, mixing between shallow and deep groundwaters, evaporation occurred from the spring orifice to the sampling locations and consequent isotopic disequilibrium during calcite precipitation (pentecost, 2005; andrews, 2006; and references therein). δ13c reflects the sources of carbon which contribute to the carbon species in solution, the tendency of co2 dissolved in the groundwater to equilibrate with atmosphere and evade at surface emergences, and, subsequently, along the surface flow (pentecost, 2005; andrews, 2006; and references therein). considering the context of channelized flow of thermal waters and the sampling locations at a certain distance from the springs, the temperature drop is an important factor on which the oxygen isotope composition depends; it also influences the amount of co2 evasion (the increase in distance implies a progressive thermal decline). air temperature induces, when lowers or rises, an increase or decrease in δ18o, whereas δ13c behaves oppositely since higher temperature favors co2 evasion leaving behind a residual co2 isotopically “heavier” and vice versa. this implies that the records of carbon and oxygen isotopes will be negatively correlated when temperature is the main factor to influence isotopes in carbonate formation. oxygen isotopes in travertine carbonates may also depend on the variations of oxygen isotope composition of groundwater which is, in turn, derived by meteoric precipitation; isotope ratios in precipitation are averagely lower in cold climates and higher in warm periods, an effect that can be more or less evident in groundwaters according to precipitation intensity. cold humid climatic conditions may promote soil biogenic co2 formation, resulting in isotopically light carbon isotope ratios. the increased introduction of soil co2 into groundwater produces a lowering in the δ13c of the calcite precipitated around the springs. in the case of the area studied this lowering was modulated by heavy carbon co2 sources, generated by decarbonation of local bedrock and mantle degassing, of which the local thermal system is rich (dilsiz, 2006; kele et al., 2011). these mechanisms, however, generate carbon and oxygen isotope records that co-vary positively. on the basis of the isotope record profiles, it seems that the factors described above may have influenced recent past waters at hierapolis thermal springs and the calcium carbonate of the channels. variations in δ13c seem to correlate positively with δ18o at higher frequency oscillations, whereas negatively at lower frequencies. these evidences may be related to the mechanisms above described: δ13c/δ18o positive covariance can be related to the variation in air temperature, whereas negative covariance to the variations in climate and precipitation regime reflected in groundwater isotopes. cross wavelet spectral analysis was applied to study the oscillatory nature of the isotope data records to investigate the different responses in time to climate variations (fig. 2c). the mathematical basis of this technique is given by grossmann & morlet (1984) and a complete description by torrence & compo (1998). the wavelet analysis carried out in this study was performed using the free matlab-software package (wtc-r16) available at the url: http://noc.ac.uk/using-science/crosswaveletwavelet-coherence (grinsted et al., 2004). a physically consistent definition of energy for the wavelet power spectrum has been adopted following liu et al. (2007) to tab. 1 age difference (∆t) in years between the levels where samples of channel b and c were selected. sample collected from the middle of channel c was at 3.80 m from the bottom. 230th, 232th were determined by isotope dilution alpha spectrometry, 226ra and 238u were determined by high resolution gamma spectrometry. stable isotope stratigraphy of travertine sequences allow a direct comparison of the spectral peaks across scales. following guyennon et al. (2014), the associated global cross-wavelet spectrum is defined for amplitude (gxws-amplitude) and phase (gxws-phase) as the time integration of the significant (p value <0.05) wavelet coefficients. the gxws amplitude and phase gives a synthetic description of the main common signals characterizing the time series. wavelet analysis reveals spectral peaks of significant intensity at frequencies corresponding to 7 and 1112 years, especially evident in sequence c which has higher resolution; for these periodicities the c and o records are prevalently in phase. at lower frequencies in sequence c, it is possible to evidence spectral peaks between 25 – 35 and at 65 years, with c and o records prevalently in phase opposition; whereas in sequence b, peak at 50 years with c and o records in phase. the periods from 7 to 12 years can represent the response of the data to the aquifer dynamic pulses which, being influenced by meteoric precipitation, are strongly linked to shallow, fast aquifer circulation and to alternation of not only cold/warm climate but also humid/ arid conditions. at higher periodicities, around 30 yrs and 65 yrs, the surface temperature oscillation seems to have influenced most the record c. the peak at 50 years recorded in the sequence b should be related to climatic variation filtered by the local aquifer system; this peak is not observed in the record of sequence c. the sampling location of the two channels with respect to the spring orifice are surely different and this may have played a role on this discrepancy; the b sampling site is closer to the spring orifice than the c sampling site, as indicated from the average carbon isotopic composition of the two channels δ13c = +6.2‰ in b; δ13c = +6.7‰ in c). the carbon isotopic composition of b lower than c may indicate a larger co2 degassing effect at site c, therefore a shorter distance traveled by the water to reach the site b. an average 0.5‰ difference, considering the magnitude of amplitude variations observable in the carbon records, can be considered significant to obfuscate the co2 evasion effect and recording the co2 variations related to the co2 mixing occurred in the groundwater system. 4. conclusion two sequences reconstructed from travertine channel deposits used at hierapolis of phrygia as water collectors were analyzed for carbon and oxygen isotope stratigraphy. the radium-226 dating method constrained the time interval covered by the sequences revealing that the channel b sequence is shorter in duration (790±71 years) and the channel c sequence is longer (995±71 years). it is likely that the top of both sequences can be dated close to the 1354 ad, when a strong earthquake destroyed the city and led to the abandonment of the area. isotope records show decadal-scale, pseudo-periodic fluctuations related to climatic variations. the study was facilitated by using cross wavelet spectral analysis to evaluate the most powerful frequencies of oscillation. air temperature seems to play an important role in influencing the data records; the fluctuations, which seem related to this factor, show periods around 30 and 65 years. whereas 128 fayek a. et al. fig. 2 panel (a) presents the δ13c (cyan full line, left axis) and δ18o (blue full line, right axis) time series for channel b. panel (b) presents the δ13c (orange full line, left axis) and δ18o (red full line, right axis) time series for channel c. panel (c) presents the global crosswavelet spectrum (gxws) between δ13c and δ18o in terms of phase (dash line) and amplitude (full line) for channel b (blue lines) and channel c (orange lines). higher frequency pulses at periodicities of about 7, 10, 12 years seem to be related to the shallow aquifer dynamics. the sequence b shows that climatic oscillations with periods around 50 years can be attributed to the filtering of the aquifer system to air temperature periodic variations. acknowledgments the authors wish to thank the italian archaeological mission at hierapolis (maier) for having made the access to the archaeological site of hierapolis possible. references andrews j.e. 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(1858) exploration archéologique en asie mineure, paris. 129 stable isotope stratigraphy of travertine sequences ms. received: may 15, 2018 final text received: may 21, 2018 130 amq abs mannella et al palcom 141-145.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 137 141 fucino palaeo-lake: towards the palaeoenvironmental history of the last 430 ka giorgio mannella 1, biagio giaccio 2, giovanni zanchetta 1, eleonora regattieri 1, niklas leicher 3, stephanie scheidt 3, thomas grelle 4, carlos lehne 4, christian rolf 4, thomas wonik 4, sebastien nomade 5, alison pereira 5,6, elizabeth niespolo 7,8, paul renne 7,8, melanie leng 9,10, jonathan dean 9,10, camille thomas 11, daniel ariztegui 11, mario gaeta 12, fabio florindo 13, gian paolo cavinato 2, antonello provenzale 14, bernd wagner 3 1 dipartimento di scienze della terra, university of pisa, pisa, italy 2 institute of environmental geology and applied geoengeneering (igag cnr), roma, italy 3 institute of geology and mineralogy, university of cologne, cologne, germany 4 leibniz-institute for applied geophysics, rock physics & borehole geophysics, hannover, germany 5 laboratoire des sciences du climat et de l’environnement (cea-cnrs-uvsq), gif-sur-yvette, france 6 ecole française de rome, roma, italy 7 department of earth and planetary science, university of california, berkeley, usa 8 berkeley geochronology center, berkeley, usa 9 centre for environmental geochemistry, school of geography, university of nottingham, nottingham, uk 10 nerc isotope geosciences facilities, british geological survey, keyworth, nottingham, uk 11 section département des sciences de la terre et de l'environnement, université de genève, genève, switzerland 12 dipartimento di scienze della terra, university of roma “sapienza”, roma, italy 13 istituto nazionale di geofisica e vulcanologia, roma, italy 14 institute of geosciences and georesources (igg cnr), pisa, italy corresponding author: g. mannella <giorgio.mannella@dst.unipi.it> abstract: the sedimentary succession deposited in fucino palaeo-lake potentially records the environmental history of the central mediterranean region continuously since the early pleistocene and up to recent historical times. fucino palaeo-lake sediments are interbedded with numerous volcanic ash layers which allow the reconstruction a robust and independent chronological framework of past environment changes. this framework is a fundamental tool to synchronise different archives at a regional and extra-regional scale and to better understand the spatio-temporal climate variability in the quaternary at the orbital and millennial-scales. here we present new preliminary data for the last five glacial to interglacial cycles. keywords: fucino palaeo-lake, drilling, core catcher, quaternary, volcanic ash 1. introduction in june 2015 drilling operations in fucino basin resulted in the recovery of a 82 m long pilot core (cores f1-f3 in fig. 1) documenting the interval from early marine isotope stage (mis) 6 to late holocene. investigations on cores f1-f3 (giaccio et al., 2015a; 2017) documented the potential for this natural archive to produce a regionally representative and independently dated record of climatic variability. from a chronological point of view, the site is particularly relevant because of its proximity to quaternary peri-tyrrhenian volcanic centres. (fig. 2). these volcanic centres had an intense explosive activity which resulted in the deposition of a number of tephra in the basin. these tephra layers can be used today as important chronological and stratigraphic marker beds (e.g. giaccio et al., 2012, 2015b; regattieri et al., 2017). this is a crucial requirement for comparing intraand inter-regional palaeoclimatic records based on different dating methods. in particular, the rich tephrostratigraphic content poses the basis for a better understanding of the temporal relationship between them and with respect to the main climatic forcing (e.g. orbital). furthermore it allows to evaluate differences in magnitude and expression of quaternary palaeoclimatic change across regions. with the purpose to extend back in time the record, a new drilling campaign (cores f4-f5) was set in fucino basin in june 2017. the preliminary analyses so far performed on the lacustrine marls and the chronological assistance provided by the tephro-stratigraphic framework, indicate that the recovered succession continuously spans the last five glacial to interglacial cycles, i.e. from mis 12/mis 11 up to the holocene. 2. geological setting the fucino basin, located in the central apennine chain, abruzzo (fig. 1a), is the largest intermountain basin in the central apennines. this basin is an active tectonic basin and its evolution was controlled by two antithetic fault systems (ne-sw and nw-se; galadini & galli, 2000). the opening of the basin, possibly concurrent with the onset of lacustrine sedimentation, commenced in the early pleistocene in response to an extensional phase along the apennine chain (e.g. d’agostino et al., 2001). unlike other basins in this region, fucino lake has continuously existed since the early pleistocene and till 1875 ad, when the lake was artificially drained. https://doi.org/10.26382/aiqua.2018.aiquaconference 142 f ig .1 r e fe re nce m a p o f th e f ucino b a sin (a ) lo ca tion o f f u cin o b asin w ith respe ct to the m a in e ru ptive cente rs a ctive d urin g th e last 1.8 m a . (b ) s h ad ed relief o f th e f u cino p la in sh o w ing th e lo ca tio n o f th e g e ol azio (g l ), t e lespa zio (t s ), s tra da p ro vinciale 20 (s p ), f ucino 1 a n d 3 (g iaccio e t a l., 20 15 ; 20 17 ) an d 4 an d 5 (th is stu dy) bo re ho les. d a she d blu e line s a re the isochron es (in m s) o f the p lio-q u ate rna ry in filling w ith respe ct to th e q u a te rn a ry m aste r fa u lts (b old red line s= re sp on sib le fo r th e a sym m e trica l (h a lf-g rab en ) ba sin ge o m e try. d otted green lin es a re th e traces of th e a va ila b le se ism ic lin es. (c) s e ism ic lin e 3 (see tra ce in p a ne l b ) sho w ing th e in te rn a l a rchitectu re o f th e p lio-q u aterna ry co n tine n ta l d ep o sits o f the f ucin o b asin a lon g a w -e orie nte d p ro file . t he pro jected lo ca tio n o f th e g l , s p , f 1 -f 3 an d f 4-f 5 bo reh o le s is a lso sh ow n . a , b , c : m a in u n co nform itie s; s e q . 2 m essin ia n fo red ee p sed im en ts; s e q. 3: p lio ce ne flu via l a nd a lluvial de po sites; s eq . 4 : q ua te rna ry lacustrine an d flu via l de po sits. f ig u re m od ified after g iaccio e t a l. (201 5 a). mannella g. et al. 143 3. material and methods 3.1 drilling operations the drilling site (fig 1 b, c) was selected by evaluating the sedimentation rate obtained from the combined interpretation of tephro-chronological information collected from pre-existing cores (see fig. 1 caption) and the general sedimentary-tectonic architecture of the basin (fig. 1 b, c). compared to the previous drilling site (f1-f3), the f4-f5 site provided us the opportunity of recovering a less expanded sedimentary succession. at the selected site (42.00 °n, 13.54 °e), two parallel holes down to ca. 86 m below ground level (b.g.l.). cores were recovered with identical 1.5 m long coring devices operating with an offset of 75 cm to ensure overlap between the f4 and f5 series. core catchers were subsampled directly in the field, whereas cores were carefully packed and stored for further analyses. the f4 hole was logged immediately after drilling and down to a depth of 80 m b.g.l. the logging equipment consisted of a multi-sensor (gamma ray, resistivity and magnetic susceptibility) probe operating in accord to the internal protocols of the leibniz institute for applied geophysics (liag). 3.2. preliminary core analysis core opening and core description was carried out at the university of cologne, germany. macroscopic tephra layers were directly sampled for further analyses in specialised laboratories, while for suspect cryptotephra smearslides were taken for optical-microscope analysis. cores underwent non-destructive analysis, (i.e. x-ray fluorescence scanning and magnetic susceptibility). further analyses were conducted at the palaeomagnetic laboratory in grubenhagen (einbeck, germany) of the liag. here the stable components of natural remanent magnetization (nrm) where characterised. after preliminary studies, a raw core composite was elaborated by taking into account drilling depths and clear stratigraphic markers, such as tephra layers, to match the f4 and f5 cores. this preliminary composite profile served the purposes of core sub-sampling for further analyses. subsampling was carried at a variable resolution (from 1 cm every 2nd cm to every 8th cm) and resulted in a set of more 2000 samples which are currently being processed. 3.3 geochemical analyses on core catcher material total carbon (tc), total inorganic carbon (tic), total nitrogen (tn), total sulfur (ts), and stable oxygen isotope compositions were measured on discrete samples from the top of each core catcher. samples were dried in an oven at 50 °c. after disaggregation and sieving, the fraction below 100 μm was powdered and homogenised for geochemical analyses. tn and ts were determined with a vario micro cube combustion cns elemental analyser (elementar, germany) after combustion at 1150 °c, whilst tc and tic were measured with a dimatoc 200 (dimatec, germany) at the university of cologne, germany. toc was calculated by subtracting tic from tc. 3.4. preliminary tephra analyses major and minor oxide element compositions were determined on micro-pumice fragments and/or glass shards, from some selected tephra from cores f4-f5. the analyses were carried out at the igag-cnr in rome, italy, using a cameca sx50 electron microprobe equipped with a five-wavelength dispersive spectrometer analytical. 4. results and discussion the analyses run in the core samples so far allowed us to recognise more than 130 macroscopic tephra layers. preliminary tephrostratigraphic surveys evidenced the presence of 16 tephra in common with the f1-f3 drilling site in the first 35 m. this confirmed that the uppermost 35 m in f4-f5 replicate the f1-f3 record (i.e. the last ca. 190 ka). preliminary analyses on some of the major tephra layers from the lower part of the recovered succession (i.e. below 35 m) allowed us to identify the correlatives of other important regional tephrostratigraphic markers. among these, the most relevant are listed in the table below: the vico α tephra, together with a sharp and clear change in the lithological properties of the sediment, constrains the lowermost part of our succession to the mis 11-12 boundary. results from biogeochemical analyses on the core catcher material show that the different proxies are involved in a significant variability, with major trends consistent between the different proxies (fig. 2). changes in tic are assumed to be mainly related to authigenic (i.e. biomediated) precipitation of calcite, according to the results from f1-f4 core (giaccio et al., 2015). this process could be favoured by enhanced lake primary productivity as well as by increased ca input from the catchment (e.g. gierlowsky-kordesh, 2010; vogel et al., 2010). as for toc, similarly to tic, its variation is generally controlled by the rate of organic matter production in the lake and in catchment vegetation (leng et al., 2013) and by the preservation of om. therefore higher values of both tic and toc could be linked to warmer and wetter periods (i.e. interglacials/interstadials), where ions and nutrient are flushed from the well-developed soils into the lake. the toc/tn ratio is usually related to the source of om (aquatic/terrestrial), with higher (lower) values indicating prevailing terrestrial (lacustrine) input (meyers & ishiwatari, 1995). the general variability expressed by the proxy series depicts changes of the palaeoenvironmental context, which can be interpreted in the frame of the climate fucino palaeo-lake: towards the last 430 ka variability of the last 5 glacial-interglacial cycles. this is demonstrated by the good correlation potential of the tic and toc curves from fucino lake with the lr04 benthic stack (fig. 2). during the mis 10, 8, 6 and 4-2 glacial intervals, reduced lake productivity and contraction of terrestrial vegetation with respect to the lacustrine one determined, respectively, lower tic and toc as well as lower toc/tn ratio. interestingly, despite the relatively low time resolution obtained from the core catcher material, our record shows some of the main features of the middle-late pleistocene climate variability. this is characterised by relatively abrupt glacial terminations and the progressive enhancement of the 100ka power (e.g. tzedakis et al., 2017). 5. conclusions ongoing and future investigations, including detailed petrographic and geochemical analyses and radiometric dating of tephra layers, together with highresolution biogeochemical, stable isotope and palaeomagnetic analyses, will make it possible to fully explore the potential of the fucino lacustrine succession as a long climatic archive. we are currently preparing a composite profile anchored to the sedimentary succession by borehole logging data. this represents a fundamental step to establish a reliable age-depth model. the rich tephrostratigraphic documentation appears very promising thanks to several macroscopic tephra layers and numerous cryptotephra. most of these tephra originate from the nearby peri-tyrrhenian volcanic centres, which were characterised by a peculiar eruptive history. this makes fucino tephra layers particularly suitable for both indirect (geochemical fingerprinting) and direct (40ar/39ar) dating. this will make it possible to elaborate a robust and completely independent chronology for the observed variations in biogeochemical and magnetic parameters over the interval between termination v and the holocene. such a multi-proxy and high resolution approach will allow to address in detail climatically driven environmental changes at both orbital and millen 144 fig. 2 preliminary data from fucino f4-f5 drilling plotted against drilling depths compared to the lr04 benthic stack (lisiecki & raymo, 2005). yellow and blue shadings indicate odd and even numbered marine isotope stages, respectively. mannella g. et al. nial scales and to evaluate their duration and magnitude on a broad geographic scale. references d’agostino n., jackson j. a., dramis f., funiciello r. (2001) interactions between mantle upwelling, drainage evolution and active normal faulting: an example from the central apennines (italy). geophysical journal international, 147, 475-497. galadini f., galli p. (2000) active tectonics in the central apennines (italy) input data for seismic hazard assessment. natural hazards, 22, 225–270. giaccio b., nomade s., wulf s., isaia r., sottili g., cavuoto g., galli p., messina p., sposato a., sulpizio r., zanchetta g. (2012) the late mis 5 mediterranean tephra markers: a reappraisal from peninsular italy terrestrial records. quaternary science reviews, 56, 31-45. giaccio b., regattieri e., zanchetta g., wagner b., galli p., mannella g., niespolo e., peronace e., renne p., nomade s., cavinato g.p., messina p., sposato a., boschi c., florindo f., marra f., sadori l. (2015a) a key continental archive for the last 2 ma of climatic history in central mediterranean area: a preliminary report on the fucino deep -drilling project, central italy. scientific drilling, 3, 17. giaccio b., regattieri e., zanchetta g., nomade s., renne p.r., sprain c.j., drysdale r.n., tzedakis p.c., messina p., scardia g., sposato a., bassinot f. (2015b) duration and dynamics of the best orbital analogue to the present interglacial. geology, 43, 603-606. giaccio b., niespolo e., pereira a., nomade s., renne p.r., albert p.g., arienzo i., regattieri e., wagner b., zanchetta g., gaeta m., galli p., mannella g., peronace e., sottili g., florindo f., leicher n., marra f., tomlinson e.l., (2017) first integrated tephrochronological record for the last ~190 kyr from the fucino quaternary lacustrine succession, central italy. quaternary science reviews, 158, 211-234. gierlowsky-kordesch e. h. (2010) lacustrine carbonates, in: developments in sedimentology, 61, 2-50. leng m.j., wagner b., boehm a., panagiotopoulos k., vane c.h., snelling a., haidon c., woodley e., voegel h., zanchetta g., baneschi i. (2013) understanding past climatic and hydrological variability in the mediterranean from lake prespa sediment isotope and geochemical record over the last glacial cycle. quaternary science reviews, 66, 123-136. lisiecki l.e., raymo m. e. (2005) a pliocenepleistocene stack of 57 globally distributed benthic δ18o records. paleoceanography, 20, pa1003. meyers p.a., ishiwatari r. (1995) organic matter accumulation records in lake sediments, in: physics and chemistry of lakes. (ed.) lerman a., imboden d., gat j., springer, berlin, 279-328. regattieri e., giaccio b., nomade s., francke a., vogel h., drysdale r.n., perchiazzi n., wagner b., gemelli m., boschi c., mazzini i., galli p., peronace e. (2017) a last interglacial record of environmental changes from the sulmona basin (central italy). palaeogeography, palaeoclimatology, palaeoecology, 472, 51-66. tzedakis p.c., crucifix m., mitsui t., wolff e.w. (2017) a simple rule to determine which insolation cycles lead to interglacials. nature, 542(7642), 427-432. vogel h., wagner b., zanchetta g., sulpizio r., rosén p. (2010) a paleoclimate record with tephrochronological age control for the last glacial-interglacial cycle from lake ohrid, albania and macedonia. journal of paleolimnology, 44, 295-310. 145 ms. received: may 7, 2018 final text received: may 23, 2018 fucino palaeo-lake: towards the last 430 ka 146 available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 63 67 mercury dispersion from the mt. amiata mining district to the upper reach of the paglia river (central italy): a geomorphological-geochemical approach defines the interaction between river deposits and mining activity antonella colica 1 , marco benvenuti 1 , laura chiarantini 2 , pilar costagliola 1 , pierfranco lattanzi 3 , valentina rimondi 1 , massimo rinaldi 1 1 dipartimento di scienze della terra, università di firenze, firenze, italy 2 mema, università di firenze, firenze, italy 3 cnr-igg, uos firenze, firenze, italy corresponding author: a. colica <antonella.colica@gmail.com> abstract: the paglia river drains the mt. amiata mercury district (the 3 rd most important district worldwide exploited from 1880 to 1980) before becoming a tributary of the tiber river. a combined geochemical-geomorphological approach was applied to understand hg distribution in the fluvial morphological units (mus). the hg mean values in the terraces (here after indicated as tn) seem to be linked to the mining activity: t1, formed before the activity, has values within the local background (2÷6 mg/kg); t2, t3 and t5, formed either at the beginning or in the final phases, have values lower than 9 mg/kg; t4, formed during the peak activity, has 26 mg/kg. the current baseflow channel and bar have mean value of 9 mg/kg. the high value of the modern floodplains (19 mg/kg) could be related to intense flood events causing greater erosion of contaminated mus upstream. the total contained mass of hg in the studied stretch is estimated at 63 tonnes. keywords: fluvial sediments, fluvial dynamics, morphological units, hg contamination 1. introduction between the 1880s and 1980s, the mt. amiata mining district (mamd), located in southern tuscany (italy), produced about 102,000 tonnes of hg and released into the environment not less than 30,000 tonnes of hg (benvenuti & costagliola, 2016, and references therein). mamd is located within the catchment of the paglia river, the main tributary of the tiber river, which flows directly into the mediterranean sea. in this study, an integrated geomorphological and geochemical approach was used to interpret and understand temporal and spatial contaminant distribution in the upper catchment of the paglia river. the analysed stretch of the paglia river extends over about 43 km from the source near abbadia san salvatore, where the most important hg mine of the district was located, to allerona scalo in umbria (fig. 1). the area of interest covers about 720 km 2 , straddling southern tuscany, northern lazio and central umbria. the shape of the basin and the hydrographic net are mainly linked to the structural characteristics of two grabens: radicofani and paglia-tiber (fig. 1). the main lithologies cropping out along the paglia river belong to a quaternary continental deposit complex (marroni et al., 2015), characterized by: (1) holocene fluvial deposits (pebbles in a mainly sandy-silty matrix), the paglia river cuts through its alluvial deposits locally forming various orders of terraces; and (2) pleistocene fluviallacustrine deposits (mainly conglomerates with sandysilty beds and levels). these last deposits are arranged on large terraced surfaces located at altitudes from 5 to 20 m above the current course of the paglia river (e.g. pleistocene terrace in fig. 1). 2. methods and data collection the paglia river is a relatively high-energy, dynamic river, characterized by a sequence of channel adjustments in its catchment, occurred during the period of mining activity and during the last decades. to understand this evolution, the multi-scale approach developed by rinaldi et al. (2013, 2015) and gurnell et al. (2016) was used. on this basis a series of landscape units (lus), segments and reaches were identified (fig.1). the lower hierarchical spatial order is the morphological unit (mu), i.e. an area within the floodplain channel containing a landform created by erosion or deposition of sediment, sometimes in association with vegetation. a multi-temporal analysis of the paglia river changes was performed to evaluate the evolution of channels and floodplains, and to try and date the recent terraces and modern floodplains formed during the time interval from the beginning of mining activity to present. this analysis was restricted to the following three key years: (1) the first topographic maps produced by the igm (istituto geografico militare) dating from 1883 (scale 1:50,000), coinciding with the initial period of mamd activity; (2) aerial photos from 1954 (igm gai, scale 1:33,000) corresponding to the highest production period of mamd activity; (3) aerial photos from 2012 (environmental ministry, scale 1:10,000), corresponding to the available most recent and best resolution aerial photos. maps and aerial photos were processed by gis https://doi.org/10.26382/aiqua.2018.aiquaconference analysis (using arcgis 9.3). multitemporal analysis of channel changes was then used to support interpretation and classification of the mus related to the channel evolution occurring during the investigated period. this gis-based analysis was validated by field surveys. 2.1. geomorphological field characterization of sampling transects a sampling transect was identified for each fluvial reach. a total of 11 sampling transects were selected (10 along the paglia river and 1 along siele creek, a tributary of paglia r.; fig. 1). the mus are classified (according to rinaldi et al., 2016) within two broad spatial domains, bankfull channel (baseflow channel c and bars -b) and floodplain. the latter is strongly influenced by recent channel dynamics. the channel incision and narrowing of the paglia river, occurred approximately during the last 150 years, determined the formation of a series of ‘recent terraces’ (t2, t3, t4 and t5), i.e., former historical levels of floodplain that became a terrace because of bed incision; whereas the most recent alluvial, flat surface adjacent to the river created by lateral and vertical accretion under the present river flow and sediment regime is here classified as ‘modern floodplain' (fp see belletti et al., 2016). for each transect, a profile representing the distribution, lateral extension and elevation of the different mus was obtained. the lengths (parallel and perpendicular to the watercourse) of each mu along each transect were measured on aerial photos and maps. in order to get an estimation of the volumes of overbank fine sediments accumulated within the wide channel of 1883, the thickness of the overbank fine sediments overlying the gravel bed deposits was estimated by a hand borer. then the area of each polygon of the different mus deposited after 1883 was measured by gis, and the volume of fine sediment was calculated as a product of area and thickness. the volume of fine sediment accumulated within the channel bed of 1883 was calculated for each reach, and it was then used to get an estimation of the volumes of contaminants stocked within these mus. 2.2. geochemical sampling and analysis a total of 102 samples of sediments were collected, including 82 samples from the transects along the paglia river, 7 samples from the siele transect, and 13 samples outside the studied transects from presumably pre-mining deposits (see below), to establish a comparison between preand post-mining conditions. following preliminary tests, it was ascertained that the <250 μm fraction likely contains nearly all hg of the bulk sample; this fraction was digested with aqua regia in a microwave oven, and the resulting solution was analysed by means of icp-oes. 3. results 3.1. channel and floodplain evolution considering channel widths of the three reference years in this study (1883, 1954, 2012), it appears that the paglia river suffered significant channel narrowing 64 fig. 1 geology of the upper part of the paglia river catchment (delimited by a white line) after colica (2017). the analyzed paglia river stretch is between the points with stars. landscape units (lus; their limits are highlighted with a black line): 1lu) mountain areas with volcanic and volcano-sedimentary successions and ligurian and subligurian units; 2lu) hilly areas with neogene deposits and continental deposits complex; 3lu) mainly hilly areas with ligurian and subligurian units and volcanic and volcano-sedimentary successions; 4lu) intermontane plain unit with neogene deposits and continental deposits complex. the transects are indicated by red segments and numbers. the black points indicate the beginning of the reaches along the paglia river (same numbers of transects). siele is the transect along the siele creek. the capital red letters indicate the mining areas: a) abbadia san salvatore; b) casa di paolo senna mine cerro del tasca; c) siele carpine; d) cornacchino. regional boundaries are reported in yellow. colica a. et al. 65 over time, with an average reduction in channel width of about 64% between 1883 and 1954, and a further reduction of about 70% between 1954 and 2012. channel narrowing occurred in combination with a change in the overall morphological pattern, from a braided (1883) to a single-thread, sinuous morphology (2012). the causes of these changes are a combination of land use changes (i.e., afforestation) at catchment scale with intensive sediment mining (see e.g. scorpio & rosskopf, 2016). 3.2. geomorphic characterization and interpretation of sampling transects a sequence of terraces was generated by bed incision and narrowing (fig. 2): old terrace (t1) (i.e. formed before the last 150 years), corresponding to an alluvial surface that is already recognized as higher than the floodplain in the maps of 1883; recent terrace (t2), interpreted as the modern floodplain in the maps of 1883, corresponding to the alluvial flat surface adjacent to the channel bed of 1883; recent terrace (t3), formed between 1883 and 1954, corresponding to a flat surface at an intermediate elevation between t2 and t4, interpreted as a recent terrace in the aerial photos of 1954; recent terrace (t4), formed after 1954, corresponding to the modern floodplain recognized in the aerial photos of 1954; recent terrace (t5), formed between 1954 and 2012, corresponding to a flat surface at an intermediate elevation between t4 and the modern floodplain (fp). the fp is the lowest flat and vegetated surface adjacent to the river bed, recognized in the aerial photos of 2012 and during the field survey as the channel bars (b) and baseflow channel (c). as can be seen in fig. 2, some mus that are present within the 1883 channel bed were formed during mamd mining activity: t3 during the initial phase, t4 during the maximum period of activity (1950s-60s), t5 during the final and closing stages (1980s) and possibly also after (but before 2012). 3.3. geochemical data fig. 3 reports the hg concentration in the mus in the transects along the paglia river. samples from premining deposits are characterized by hg concentrations comparable with the background estimate of the amiata area (2-6 mg/kg; rimondi et al., 2015). by contrast, many samples in all other mus show hg contents well above this background and above the italian legal limit of 5 mg/kg (dl 152/2006) for industrial soil. in particular, high values of hg concentration are shown in the following mus: t4 (hg> 30 mg/kg along transects 2.2, 2.5 and 2.6), fp (> 30 mg/kg along transects 2.2 and 2.3) and c (> 20 mg/kg along transects 2.6 and 2.7). the highest mean hg value was observed in recent t4 terraces. the highest values of hg concentration per mus were found along the siele transect: c (29.4 mg/kg), b (mean value 79.2 mg/kg), fp (mean value 183.7 mg/kg) and t4 (mean value 92 mg/kg). 3.4. total hg masses from the volumes of river sediments accumulated in the reaches and hg concentrations, we estimate a total bulk value of 63 tonnes of hg in the studied stretch (colica et al., 2016). the highest contents are found in t4 (39 tonnes), followed by fp (19 tonnes), t3 (4 tonnes) and t5 (1 tonne). considering the single reaches, reach 3.1 shows the largest amount of hg (25 tonnes), followed by reaches 2.3 (12 tonnes), 2.5 (10 tonnes) and 2.6, 2.7 and 4.1 (each containing 4 tonnes of hg). 3.5. the major flood event of february 2016 at the end of february 2016, a major flood event along the paglia r. caused the deposition of overbank deposits on top of pre-existing mus. these deposits have hg values in the 5-40 mg/kg range (stars in fig. 3) and a mean value of 21 mg/kg, similar to that of the fp (19 mg/kg). comparing these data with those collected from the major flood of november 2012 (pattelli et al., 2014; circles in fig. 3), it is evident that large quantities of hg-contaminated sediments have been transported during major flood events. specifically, the hg concentration in transect 2.2 is about four times higher in the 2016 event compared to that of 2012. 4. discussion on the basis of the geomorphologic-geochemical analysis, it can be stated that current and recent mus in the paglia river basin are locally heavily contaminated by hg. in particular, the most contaminated mu t4 was formed during the peak of the mamd mining activity. on the other hand, the high hg values of fps could be due both to the last flood events, which deposited abundant amounts of sediment and contaminated materials along the river banks, and to the recent local partial enlargement of some reaches of the paglia river. the t3 unit was presumably formed around the beginning of the mamd mining activity and immediately prior to the peak activity period. in this mu hg content is less than the two previous cases, but the total hg bulk is about 4 times higher than in t5; this last unit, formed after 1954 and before 2012, contains sediment with low hg content, probably as a result of the closure of the mining activities in the 1980s. it is important to highlight how the erosion of some mus can result in a high environmental risk due to their high mass of contaminants. it should also be noted that the eventual securing of these mus areas must take into fig. 2 range and mean values of hg concentrations (mg/kg) in the different mus along the paglia river, modified from colica (2017) hg dispersion from amiata mining district to paglia river account that in every major flood event large quantities of heavy hg contaminated sediments might be transported and redeposited on the pre-existing mus. the influence of the paglia river tributaries appears to be fundamental in the supply of hgcontaminated sediments (fig. 3). in particular, the pagliola creek drains the mining area of abbadia san salvatore and, despite the ongoing reclamation in this area, it carries high hg concentrations in fluvial sediments during flood events (e.g., fp of transect 2.2 contains 98 mg/kg hg). indeed, the deposits of the baseflow channel (c) and bar (b) sampled during a period without intense floods (2013-2014) show hg contents less than 1 mg/kg. the presence of high hg values in recent t4 terraces (fig. 3; transect 2.2) may also be due to the presence of more contaminated sediments in the 1954 fp, following the period of maximum activity in the abbadia san salvatore mining area. the siele creek drains the siele-carpine mining area. although reclamation was completed in 2001, the siele transect shows the highest hg concentrations in various mus (e.g., samples c, b, fp and t4). the contribution of highly polluted sediments from the siele creek to the paglia river is clearly recorded in the hg contents of c and b from transect 2.6 (fig. 3). this phenomenon also occurred during the formation of recent and past fps (e.g., hg values in t4 terraces). the presence of high hg concentration in t4 at transect 2.5 (fig. 3) is due to the 1954 local existence of an extended fp in which hg-contaminated river sediments could accumulate more easily. 5. conclusions based on the above geomorphologic-geochemical approach, variable, locally elevated hg concentrations in the paglia river sediments, belonging to the various mus, were found in both the transects and along the watercourse. the total mass of hg in the different mus also varies considerably. this variability is conditioned both by past and current fluvial dynamics and, until the 1980s, by mamd activity, whose effects are still affecting the fluvial environment. the total mass of hg in mus of the analysed paglia river stretch (43 km) is estimated to at least 63 tonnes. during major flood events, the paglia river appears to carry sediments with high concentrations of hg. the tributaries of paglia river contribute to this process, in particular the pagliola creek, which drains the mining area of abbadia san salvatore, and the siele creek, which drains the sielecarpine mining area. this latter creek carries sediments with the highest concentrations of hg in all current flow conditions. the course of the paglia river has undergone and is undergoing strong fluvial dynamics; particularly, since 1883 there has been a gradual incision. the most recent mus can be eroded, and thus become secondary sources of contamination. however, a recent reversal fluvial trend, a partial enlargement of some reaches, was locally observed. where this last phenomenon occurs, there are favorable conditions for a greater accumulation of contaminated sediments. knowledge of paglia river dynamics and of its current and past mus is crucial for identifying areas with greater environmental risk. the survey methodology that com 66 colica a. et al. fig. 3 hg concentrations in mus along the paglia river transects with locations of the tributaries after colica (2017). the italian legal limit (5 mg/kg; dl 152/2006) for hg in industrial soil is reported. the values are the mean of the hg concentration in the two banks. hg concentrations in the overbank deposits after the major flood events of february 2016 (stars) and november 2012 (circles) are here reported. bines geomorphologic and geochemical aspects is apparently a very effective tool for identifying these mus, understanding current and potential environmental hazards and conducting future monitoring that may have relevance for restoration measures of the affected matrices. references benvenuti m., costagliola p. 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(2016) channel adjustments in a mediterranean river over the last 150 years in the context of anthropic and natural controls. geomorphology, 275, 90-104. 67 hg dispersion from amiata mining district to paglia river ms. received: may 1, 2018 final text received: may 18, 2018 68 available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 105 108 climatic and oceanographic changes in the azores region during the last 74.7 ka alessandro bonfardeci 1, antonio caruso 1, annachiara bartolini 2, franck bassinot 3, marie-madeleine blanc-valleron 2 1 dipartimento di scienze della terra e del mare, università degli studi di palermo, palermo, italy 2 cnrs umr 7207 cr2p, mnhn, paris, france 3 institut pierre-simon laplace, lab. des sciences du climat et de l'environnement, umr8212, cea-cnrs-uvsq, gif-sur-yvette, france corresponding author: a. bonfardeci <alessandro.bonfardeci@unipa.it> abstract: in this study, we reconstruct the complex palaeoclimatic and palaeohydrographic history of the north atlantic ocean during the upper pleistocene-holocene, through a high-resolution globigerinoides ruber globigerinoides elongatus plexus study. the studied core (ata13-of-kt1) was collected southwest of the azores islands near the present-day boundary of the subtropical gyre/azores front current system (stg/afcs). quantitative and stable isotope data of the g. ruber g. elongatus plexus chromotypes and selected morphotypes showed cyclic oscillations of the stg/afcs boundary linked to climatic variability at orbital and millennial scales, during the last 74.7 ka. keywords: foraminifera, stable isotopes, palaeoclimatology, palaeoceanography, subtropical gyre, azores front/current system 1. introduction the atlantic meridional overturning circulation (amoc) is known to be the surface and deep-water movements system that controls the north atlantic hydrography (fig. 1; lynch-stieglitz et al., 2007; bonfardeci et al., 2018). the azores current (ac), originating as the eastern branch of the gulf stream, flows to the south of the azores archipelago throughout the year, centred at 34°n (schiebel et al., 2002a-b). this current is limited to the north by the so-called azores front (af) that separates the warmer and oligotrophic waters belonging to the subtropical gyre (stg) from the northernmost colder and nutrient-rich eastern north atlantic central water (enacw) (gould, 1985; schiebel et al., 2002a-b; schwab et al., 2012; repschläger et al., 2015). moreover, the ac represents the main surface waters input for the mediterranean basin and its intensity is strongly forced by the mediterranean outflow water (mow) (schwab et al., 2012). globigerinoides ruber (d’orbigny, 1839) gr. alba and rosea, and globigerinoides elongatus (d’orbigny, 1826) are common species in tropical/subtropical biogeographic provinces (bé and torderlund, 1971; bé, 1977) and they have been extensively used to reconstruct past sea-surface temperature and salinity. however, these two species exhibit morphological variability linked to different environmental conditions (aurahs et al., 2011; schiebel & hemleben, 2017). in this study, we test the link between environmental conditions and morphological variability of the g. ruber g. elongatus plexus and its response to climatic changes at orbital and millennial-scale (bonfardeci et al., 2018). the main aim of this work was to analyse latitudinal shifts in the subtropical gyre/azores front current system (stg/ afcs), using the quantitative abundance and isotopic variations of the different g. ruber g. elongatus (eco-) morphotypes as sensors. 2. material and methods the ata13-of-kt1 core (35°24.956’n 37° 15.749’w; bathymetry= 3,431 m; length= 4.03 m), collected with a kullenberg gravity corer during the oceanograflu 2013 cruise, was sub-sampled every 1 cm, with a total of 402 samples. the quantitative analyses on g. ruber g. elongatus plexus of ata13-of-kt1 core were performed on the >125 and 250-315 μm size-fractions. stable isotope analyses were performed every 2 centimetres, in the size -fraction 250-315 μm, on about ten specimens of g. ruber s.s., whereas further analyses on different morphotypes were carried out in two strategic intervals: 0-18.5 cmbsf and 42.5-60.5 cmbsf (bonfardeci et al., 2018). the isotope analyses were performed at the lsce (laboratoire des sciences du climat et de l’environnement gif-sur-yvette, france). 3. results for the age model developing four ams 14c dating and the δ18o g. ruber s.s. record were combined. the ams 14c analyses were preferentially carried out on surfacedwelling species (globigerinoides spp.). a reservoir age correction (rsurf) of 400 a was used, except for the 39-40 cmbsf level, corresponding to the heinrich event 1 (h1), where a rsurf of 800 was adopted (bard et al., 1998; siani et al., 2001). according to the tuning strategy, g. https://doi.org/10.26382/aiqua.2018.aiquaconference mailto:alessandro.bonfardeci@unipa.it� ruber gr. alba and δ18og.ruber s.s. maxima and minima were aligned to the ngrip δ18o (north greenland ice core project members, 2004) and the md95-2042 δ18og. bulloides records (lisiecki & stern, 2016). mean sedimentation rate of 5.6 cm ka-1 (temporal resolution of 178.5 a cm-1) was calculated, with an uncertainty of 2-3 ka (lisiecki & stern, 2016). the time interval covered by the ata13-of-kt1 core record spans from 74.7 to 2.75 ka bp (bonfardeci et al., 2018). the d18o g. ruber s.s. reached maxima values (from 2.1 to 0.8‰) during mis 4 and 2 stages (fig. 2), whereas decreased in correspondence with warmer mis 1 and mis 5.1 phases (from 1.7 to 0.4‰). high frequency/low amplitude fluctuations observed in the d18og.ruber s.s. record were linked to sub-orbital climatic oscillations, such as heinrich and dansgaard-oeschger events. g. ruber gr. alba increased in abundance during warm climate phases (mis 5.1 and mis 1) with maxima percentages (10-20 %) during the holocene (fig. 2), whereas minima (2-12.5 %) were observed during mis 4 and miss 3.1/2 transition. within the g. ruber g. elongatus population, g. elongatus became dominant (up to 50 %) during warmer periods (miss 5.1, 3.3, 3.1 and 1) and during the bølling/allerød–younger dryas interval, g. ruber cyclostoma type reached maximum abundances during insolation minima and glacial periods (mis 4 and mis 2), with a remarkable peak for h7, and it was almost absent in interglacial mis 5.1 and especially in mis 1 (bonfardeci et al., 2018). 4. discussion and conclusions abundance fluctuations of g. ruber gr. (alba and rosea), as well as of the g. ruber g. elongatus plexus morphotypes, testify that the azores region climate and hydrography were strictly controlled by orbital and suborbital forcing, during the last 74.7 ka. in particular, g. ruber gr. (alba and rosea) reached highest abundance during climatic phases in which the insolation signal was closely in phase with the obliquity (laskar et al., 2004). therefore, this latter group of species has been used as monitor for the expansion/reduction of the north atlantic stg (repschläger et al., 2015; bonfardeci et al., 2018). g. ruber gr. alba (fig. 2) increases in abundance, coeval with δ18og. ruber s.s. lightening, indicate that during the final part of mis 5 and the holocene the azores region was interested by warmer, stratified and oligotrophic surface waters, due to the stg expansion. conversely, during the glacial stages (miss 4 and 2) and the heinrich events, cooler, nutrient-richer and saltier waters, forced by stg reduction, dominated this region, as testified by g. ruber gr. alba decreases and δ18og. ruber s.s. weighting (bonfardeci et al., 2018). analysing the quantitative distribution of each ecomorphotype in the g. ruber g. elongatus plexus, g. ruber cyclostoma type represents the best cooler waters indicators, reaching maxima abundance during the miss 4 and 2, whilst g. elongatus, increasing in abundance during interglacial periods (latest part of mis 5.1 and mis 1), can be considered as the best warmer waters indicator in the azores region. according to bonfardeci et al., (2018), the difference between the amount of g. elongatus and g. ruber cyclostoma type represents a 106 fig. 1 present north atlantic surface hydrography and ata13-of-kt1 core location (modified from bonfardeci et al., 2018). gs=gulf stream; nac=north atlantic current; ac=azores current; af=azores front; pc=portuguese current; cc=canary current; mow=mediterranean outflow water; stg=subtropical gyre; enacw= eastern north atlantic central water. bonfardeci a. et al. 107 powerful tool to track stg expansion/reductions and related stg/afcs boundary latitudinal shifts (fig. 2). references aurahs r., treis y., darling k., kucera m. 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/hrv (za stvaranje adobe pdf dokumenata najpogodnijih za visokokvalitetni ispis prije tiskanja koristite ove postavke. stvoreni pdf dokumenti mogu se otvoriti acrobat i adobe reader 5.0 i kasnijim verzijama.) /hun 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can be opened with acrobat and adobe reader 5.0 and later.) >> /namespace [ (adobe) (common) (1.0) ] /othernamespaces [ << /asreaderspreads false /cropimagestoframes true /errorcontrol /warnandcontinue /flattenerignorespreadoverrides false /includeguidesgrids false /includenonprinting false /includeslug false /namespace [ (adobe) (indesign) (4.0) ] /omitplacedbitmaps false /omitplacedeps false /omitplacedpdf false /simulateoverprint /legacy >> << /addbleedmarks false /addcolorbars false /addcropmarks false /addpageinfo false /addregmarks false /convertcolors /converttocmyk /destinationprofilename () /destinationprofileselector /documentcmyk /downsample16bitimages true /flattenerpreset << /presetselector /mediumresolution >> /formelements false /generatestructure false /includebookmarks false /includehyperlinks false /includeinteractive false /includelayers false /includeprofiles false /multimediahandling /useobjectsettings /namespace [ (adobe) (creativesuite) (2.0) ] /pdfxoutputintentprofileselector /documentcmyk /preserveediting true /untaggedcmykhandling /leaveuntagged /untaggedrgbhandling /usedocumentprofile /usedocumentbleed false >> ] >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice amq sr05 ghirotti et al 157-164.pub one of the hazardous neighbours of the vajont landslide: the historical m. salta rock-block slide-rock fall. monica ghirotti 1, lisa borgatti 2, gianluca marcato 3 1 department of physics and earth science, university of ferrara, ferrara, italy. 2 department of civil, chemical, environmental, and materials engineering (dicam), university of bologna, bologna, italy. 3 research institute for geo-hydrological protection, national research council of italy, padova, italy. corresponding author: m. ghirotti <monica.ghirotti@unife.it> abstract: in the vajont valley (north-eastern alps), the everlasting interactions between endogenic (tectonic, seismic, isostatic) and exogenic (glacial, slope, anthropogenic) processes have resulted in a hazardous environment. the most striking geomorphological feature of the valley is the evidence of several landslide processes of different type, age, and size. the october 1963 catastrophic landslide is undoubtedly the most notorious one. however, the pineda and salta landslide events have left enduring signatures in the landscape of the valley. in particular, the wide landslide deposit upslope casso, on the southern slope of m. salta, derives from multiple overlapping events. rock planar slides, topples, and rock falls occur since centuries, displaying a complexcomposite style of activity. nowadays, in this area, slope processes are still active and are threatening the village of casso and the visitors of the 1963 disaster site. keywords: complex historical landslide, kinematics, vajont valley, north-eastern alps, italy. � available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 33 (2), 2020, 157-164 1. introduction the vajont valley, located in the eastern italian alps in the buffer zone of the dolomites unesco world heritage site, is a left-hand tributary of piave valley. it can be considered a typical alpine valley displaying an assemblage of landforms and deposits originated mainly by glacial and fluvial processes. however, the most striking feature of the vajont valley is the diversity of landslide processes, in terms of types, sizes and ages. the valley has been prone to slope instability ever since, due to its geologic, tectonic and geomorphologic settings. among the widespread active, inactive and dormant slope instability phenomena, the most relevant in terms of geomorphological risk, long-lasting evidence in the landscape and damage are the salta, the pineda and the vajont landslides (fig. 1, 2a). the most impressive one is certainly that related to the october 1963 catastrophic event (rossato et al., 2020). nevertheless, the southern salta slope is still posing a residual risk to the downstream village of casso. the main geomorphological features of these landslides are here briefly described, focusing on the salta area for which some original geomorphological and historical data are provided. 2. geological and geomorphological setting 2.1. geology in the vajont valley the geological formations range in age from the upper triassic (dolomia principale) to the middle eocene (flysch). the erto basin is connected with the tertiary formations outcropping in the core of the sinclyne: the steep slopes sourronding the valley are ascribed either to faults or mostly to hard rocks outrcopping in the syncline flanks. the local stratigraphic series is represented in the legend of fig. 2c. however, due to the presence of the m. borgà thrust (fig. 2), in the section representative of the m. salta landslide, only the following formations outcrop: scaglia rossa (upper cretaceous-lower paleocene; ~300 m thick). it is a monotonous succession of marls and red marly limestones; the typical facies is completely lacking of resedimentation features. socchèr limestone (lower-upper cretaceous; 150 m thick). alternation of microcrystalline limestones, calcarenites and bioclastic-intraclastic calcirudites with nodules and beds of chert. vajont limestone (dogger; 450 m thick). oolitic calcarenites, massive or layered in thick beds, intercalated with decimetric layers of brown basinal micrites and intraformational breccias. igne formation (middle-upper lias; 0 150 m thick). remarkable lithological heterogeneity, it consists of alternating marls and marly limestones, organic black shales, green and red nodular limestones. soverzene formation (lower-middle lias; 600 m thick). monotonous succession of frequently dolomized grey or brown micrites, rhythmically alternating with centimetric layers of grey and yellow marls; black chert in nodules and beds. https://doi.org/10.26382/amq.2020.11 158 ghirotti m. et al. 2.2. tectonics the vajont valley follows the core of an alpine syncline (erto syncline) with an e-w to wnw-ese trending axis (riva et al., 1990) gently plunging towards the e. the erto syncline lies on the hanging wall of the belluno thrust, one of the main structures of the venetian south-vergent alps (doglioni, 1992; massironi et al., 2013) and it is paired with a frontal asymmetric structure, the belluno anticline. the northern limb of the erto syncline is reversed and stretched by the m. borgà thrust, an older thrust passively transported on the back of the belluno thrust. the regional m. borgà thrust fig. 2 a) tectonic map of the western part of the vajont valley and vajont valley landslides. labels of symbols: ce: col delle erghene fault; ctr: col tramontin fault; sa: m. salta overthrust; sp: le spesse overthrust; cvc: costa vaseicalta faults; cto: col delle tosatte fault; se: erto syncline. b) tectonic cross-section at a regional scale. legend: p tr = permian-triassic; j = jurassic; k = cretaceous, t = tertiary (modified after doglioni, 1992); c) geological section. 1a quaternary; 1b fluvial gravels filling the vajont epigenetic gorge; 1c 1963 vajont landslide deposit; 2 scaglia rossa fm. (upper cretaceous-lower paleocene); 3 cretaceous-jurassic fms. (socchér fm. sensu lato and coeval): 3c socchér fm. sensu stricto, 3d ammonitico rosso and fonzaso fms.; 4 vajont limestone (dogger); 5 igne fm. (upper liassic); 6 soverzene fm. (lower and middle liassic); 7 dolomia principale (upper triassic) (modified after riva et al., 1990; semenza & ghirotti, 2000). fig. 1 view of the vajont valley seen from east, with its main landslide accumulations concentrated in a restricted area. here, the landslides, and the geological bodies, can be viewed as elements of the memory (modified from dolomiti project srl). 159 one of the hazardous neighbours of the vajont landslide: the m. salta rock-block slide-rock fall uplifts limestone jurassic in age on top of the scaglia rossa fm. the m. borgà thrust is limited to the east, south and west by the m. salta overthrust (sa in fig. 2), which separates the jurassic formations of the thrust itself from the underlying scaglia rossa. the le spesse overthrust (sp in fig.2) runs almost parallel to sa and develops within the scaglia rossa unit for almost all its path. the tectonic element between these two lines has been interpreted as a reversed wedge of scaglia rossa, detached from the top of the series that was overtaken by the m. borgà thrust, and pushed forward during its motion. 2.3. geomorphology the main geomorphological feature of the vajont valley is the presence of several huge landslide deposits of different type, age and size, that will be described in the following sections. however, besides landslides, the valley is also rich in glacial and fluvial deposits and karst landforms (pasuto, 2017). the glacial history of the region is poorly known, since related landforms have been dismantled by subsequent slope and karst processes, especially in vajont valley. during the last glacial maximum (lgm), the hanging vajont valley was probably occupied by a local glacier merging into the main piave glacier. afterwards, the valley has been dammed several times by landslides activated during or after deglaciation (wolter et al., 2016). as a consequence, the vajont stream has been from time to time diverted northwards and southwards, probably cutting more than one persistent and deep epigenetic gorges prior to the catastrophic 1963 failure (fig. 2c). 3. landslide types and processes in the vajont valley 3.1. the neighbouring landslides the vajont landslide (northern italy) is one of the best known and most tragic examples of a natural disaster induced by human activity. the northern slope of m. toc underwent nearly 3 years of intermittent, slow slope movements, beginning at the time of the first filling of the reservoir. on the 9th october 1963 at 22:39 local time, during the third reservoir emptying, a catastrophic landslide suddenly occurred on the southern slope of the vajont dam reservoir and the whole mass collapsed into the reservoir itself. the failed mass (270 mm3 of rock) drove the water of the reservoir forward, giving rise to a wave, which overtopped the dam at a height of more than 100 m above the crest and hurtled down the vajont gorge to the piave valley floor. the flood destroyed many villages and almost 2000 people lost their lives. the slide moved a 250 m thick mass of rock some 300 to 400 m horizontally with an estimated velocity of 20 to 30 m/s, before running up and stopping against the opposite side of the vajont valley. at present, the area affected by the 1963 landslide is subject to environmental and town planning restraints. numerous initiatives have been carried out in order to keeping the memory of the catastrophic disaster alive (rossato et al., 2020). the pre-historic pineda landslide, similarly to the vajont landslide, has had a large impact on the morphology of the valley (pasuto, 2017; ghirotti et al., 2013). it has detached from the steep, bare slope on the north of m. borgà (fig. 2a). it can be defined as a translational landslide (dykes et al., 2013) which turned into a rock avalanche (esposito et al., 2015). the sliding surface is visible on the right side of the valley along a footpath that connects the villages of casso and erto, while the large accumulation is located at the base of the opposite slope. the landslide would have dammed the vajont river and mesazzo stream, with implications for river course, erosion of the landslide dam, and evolution of the valley geomorphology (esposito et al., 2015; wolter et al., 2016). the source area is currently characterized by a debris cover which is often involved in debris flow phenomena. the pineda landslide overlaps a delta sequence (topset, foreset, bottomset) of glacio�uvial origin, allowing its preservation. this delta entered an extinct glacial lake, as witnessed by laminite sequences with drop-stones. a diamictite, hypothesized to be a glacial till, locally covers the pineda landslide body (masè et al., 2004; ghirotti et al., 2013). this would point to a pre-lgm age for the pineda event. 3.2. the salta landslides the salta area is located on the northern slope of the vajont valley. active slope processes are severely threatening the small village of casso, where some tens of people live. rock and debris falls originating from the uppermost part of the southern slope of m. salta, at an elevation of about 1500 m a.s.l., can be considered the most hazardous slope process still active in the valley. in the 1960s, large boulders reached the secondary road connecting the village of casso to regional road 251. since 1990, minor rock falls have been repeatedly reported on the same slope. the most recent rock fall event occurred in 2001, when five blocks detached at 1050 m a.s.l from the scaglia rossa fm. cropping out above the village of casso, fell for about 300 m and reached the outskirts of the village (tagliavini et al., 2009). the steep accumulation of the salta landslides covers a total area of about 250,000 m2 stretching between 1250 and 850 m a.s.l. and has a volume of approximately 2.5 mm3. it is composed by abundant huge blocks, which can reach a volume of some hundreds of cubic meters. marcato et al. (2007) based on the distribution of the blocks and their dimensions, suggest that the kinematics of major past events in the southern m. salta slope can be described as rock avalanches (evans & hungr, 1993). recently, a quarry has been opened east of casso to exploit the debris materials for construction purposesto set up a retaining zone to protect the village. apart the most recent events, the wide landslide deposit upslope casso appears to be the result of multiple overlapping events, but only one of these can be dated. in a written document dating back to 1688 a landslide event occurred 14 years before is referred to. therefore, it can be dated back to 1674. moreover, in a historical map dating back to 1747 found in the archive of casso church, the two branches of the deposits are clearly visible (fig. 3): one is called “motta prima de sassi cascata dalla croda di salta” (first landslide composed by stones fallen from the m. salta), the other “motta seconda” (second landslide). the main scarp is labelled as “croda cascata in due volte”, that is scarp fallen in two different moments. it can be deduced that two different events have occurred, spreading from east to west. the scarp and the accumulation zone of the 1674 event are still evident. the depicted deposit reaches the lower sector of the slope, as it can be observed even nowadays, with two distinct lobes which reach downwards altitudes between 950 and 800 m a.s.l. (fig. 4). two minor rock fall deposits, related to small scarps outcropping just north of casso, are not represented in the historical map, meaning that they could have fallen after 1747 or that they were too small to be mapped. 160 fig. 3 a) historical map of the southern slope of m. salta dating back to 1747; b) contour of the landslide body and crown areas. fig. 4 a) geological map of the southern slope of m. salta; b) geological sections and kinematic indicators of m. salta landslides. legend: 1 m. salta landslide deposits; 2 undifferentiated quaternary deposits; 3 scaglia rossa fm.; 4 socchèr limestone fm.; 5 vajont limestone fm.; 6 igne fm.; 7 soverzene fm. ghirotti m. et al. the geomorphological evolution of the slope appears to be mostly driven by the structural setting. in particular, the m. borgà thrust is certainly the main conditioning structural element that has led to the weakening of the rock mass and has driven the subsequent slope failure (fig. 4). the emplacement of the thrust has sheared the rock and has induced intensive and pervasive brittle fracturing processes (stead et al., 2019). above the thrust zone, folded and faulted bedding planes dip steeply towards the slope free face, predisposing the rock mass to failure (fig. 4). in particular, in the upper part of the slope (2050-1700 m a.s.l.) the vajont limestones dip 30° downslope, whereas in the middle part (1700-1525 m a.s.l.) the slope is still homoclinal, but the dip increases up to 45°. in the lowermost part of the slope, the bedding is dipping into the slope. the slope is characterized by the presence of different structural and landslide scarps, distributed along tectonic discontinuities. more in detail, the first series of scarps is located around 2000 m a.s.l. and it is supposed to be the remnant of even older events of the same type and style of activity as of the 1674 event. from 1700 to 1425 m a.s.l. four orders of scarps can be found, and the latter corresponds to the crown of the 1674 landslide (fig. 4a). it displays a semicircular shape and is delimited by steep walls, several meters high, carved in the vajont limestone formation. downslope, several minor scarps follow the strike of the bedding (from wnw-ese to ew). the scarp located around 1430 m a.s.l. limits a recent landslide scarp to the south. 161 the main scarp of the 1647 landslide is characterized by a series of steps forming three orders of vertical scarps reaching 20-30 m height, merging in a single irregular scarp along the western flank of the landslide crown. the historical landslide accumulation covers an area of about 160,000 m2, with a length of about 800 m and an estimated volume in the order of 1,5 mm3. its head lies at about 300 m from the lowermost scarp and is composed by huge blocks up to 840 m3 volume. the blocks have a prismatic to cubic shape and the farthest one has reached 750 m a.s.l. at places, the landslide deposit is covered by slope deposits due to erosional processes following the xvii century event. a relatively small and recent landslide deposit is in turn covering the scree slope around 1150 m a.s.l., witnessing ongoing slope instability processes (fig. 5). the 1674 landslide might have displayed a complex style of activity. the movement started as a rock block slide in the homoclinal slope evolving in a rock toppling at the front of the overthrust, where the bedding planes are sub-vertical (fig 4b, section 1). the movement continued along the slope as a rockfall. the same kinematics can be hypothesized also for landslides occurring in other sectors of the southern slope of m. salta in historical or prehistorical times (fig. 2b, section 2). the scarps of the minor westernmost landslides are characterized by a stepped morphology. the main movement appears to be by toppling, followed by slides and falls. the maximum volume of the blocks is of about 70 m3. these landslide events are supposed to be more recent since their body is not covered by any slope defig. 5 a) view of the 1674 m. salta landslide, from south: sa m. salta overthrust; sp le spesse overthrust; b) aerial view of the main geomorphological features of the landslide: the yellow circle indicates the toe of the western lobe, at present exploited by quarrying activity; the red circle shows the eastern lobe which affects the road connecting casso to the vajont valley; in the purple circle active slope deposits cover the central part of the 1674 landslide body (google earth); c) picture of the toe of the western lobe taken in ‘80s, before the opening of the quarry: the blocks are heterometric, angular, subangular, and monolithologic (vajont limestone fm.) one of the hazardous neighbours of the vajont landslide: the m. salta rock-block slide-rock fall posits. at the moment, the most hazardous sector appears to be the main scarp and its surroundings, along with the steep debris accumulation (fig. 5b and 6a). this area stretches from 1250 m a.s.l. to 1475 m a.s.l. it displays a steep and rugged morphology, developed in an intensely fractured rock mass. field surveys have revealed unstable rock blocks with volumes exceeding 1,000 m3. these blocks are separated by fractures up to 2 m wide and 10-15 m deep (fig. 6d). the shape of the scarp itself is due to the intersection of four joint sets: the main one is parallel to the bedding, and the secondary one is almost perpendicular to it. here, huge blocks (volume in the order of 300 m3) are isolated from the rest of the slope and have already undergone a backtilting movement along the bedding plane (fig. 6b). it is evident that those blocks represent a threat for the village of casso (fig. 6c). a monitoring system, based on extensometers placed across some large and open fractures located north-west of the 1674 crown between 1500 and 1600 m a.s.l., provided data about their opening and closing trends for a few years (ghirotti, 1995). unfortunately, the monitoring system is presently out of order. being this region active from the seismic point of view, the effect of seismic acceleration on the stability of the rocky scarps and of the debris has been addressed. the results of numerical modelling (marcato et al., 2007; tagliavini et al., 2009) show that the village of casso and the road could still be affected by rock falls detaching from the scarps and/or by remobilisation of debris deposits. the modelled scenarios could in principle be used for functional countermeasure works design and civil protection plans. for instance, as suggested by marcato et al. (2007), a realistic mitigation of the residual risk posed to the village of casso could foresee the continuation and progressive enlargement of the quarrying activity, in order to create a zone that could contain the debris possibly remobilised in case of co-seismic landslide events. 162 fig. 6 a) general view of the main scarp of m. salta landslide (red arrows mark the location of trenches and the extensometric net); b) a trench, more than 10 m wide and several tens of meters deep; c) outcrop of the vajont limestone fm. forming the main scarp at 1575 m a.s.l. in correspondence with the sliding surface; d) isolated rock wedges at critical stability condition, located at the eastern part of the main scarp. (figures 6a, c and d courtesy of cnr-irpi pd). ghirotti m. et al. conference field trip (october 10th, 2013). italian journal of engineering geology and environment book series no. 6, 635-646, sapienza università editrice, rome, italy. doi: 10.4408/ijege.2013-06.b-61 marcato, g., fujisawa, k., mantovani, m., pasuto, a., silvano, s., tagliavini, f., zabuski, l. (2007) evaluation of seismic effects on the landslide deposits of monte salta (eastern italian alps) using distinct element method, nat. hazards earth syst. sci., 7, 695-701. www.nat-hazards-earth-syst-sci.net/7/695/2007/ masè g., semenza m., semenza pa., semenza p., turrini m.c. (2004) le foto della frana del vajont. ed. k-flash. 1-47, 3 maps, cd-ro m with 300 photos, ferrara. http://www.k-flash.it/editoria_en.html massironi m, zampieri d, superchi l, bistacchi a, ravagnan r, bergamo a, ghirotti m, genevois r (2013) geological structures of the vajont landslide. italian journal of engineering geology and environment, book series no. 6, 573-582, sapienza università editrice, rome, italy. doi: 10.4408/ijege.2013-06.b-55 pasuto a. (2017) the vajont valley (eastern alps): a complex landscape deeply marked by landsliding. in m. soldatim. marchetti (eds.), landscapes and landforms of italy, world geomorphological landscapes, 135-145. doi: 10.1007/978-3-319-26194-2_11 riva m., besio m., masetti d., roccati f., sapigni m, semenza e. (1990) geologia delle valli vajont e gallina (dolomiti orientali). annali università di ferrara (sezione scienze geologiche e paleontologiche), 2 (4), 55-76. rossato s., ghirotti m., gabrieli f., livio f., bovo f., brezzi l., campedel p., cola s., ivy-ochs s., martin s., mozzi p., pasuto a., rigo m., simonini p., surian n., viganò a., vockenhuber c., wolter a. (2020) learning from the past to face the future: landslides in the piave valley (eastern alps, italy), alpine and mediterranean quaternary, 33, 2, 209-228. doi: 10.26382/amq.2020.14 semenza e., ghirotti m. (2000) history of 1963 vajont slide. the importance of the geological factors to recognise the ancient landslide. bull. eng. geol. env., 59, 87-97. doi: 10.1007/s100640000067 stead d., donati d., wolter a., sturzenegger m. (2019) application of remote sensing to the investigation of rock slopes: experience gained and lessons learned. isprs j. geo-inf., 8, 296. doi: 10.3390/ijgi8070296 stead d., wolter a. (2015) a critical review of rock slope failure mechanisms: the importance of structural geology. journal of structural geology, 74, 1-23. doi: 10.1016/j.jsg.2015.02.002 tagliavini f., reichenbach p., maragna d., guzzetti f., pasuto a. (2009) comparison of 2-d and 3-d computer models for the m. salta rock fall, vajont 4. conclusions the vajont valley is a tectonically and geomorphologically active area, where many large mass movements have occurred in the recent and distant past. the instability of the m. salta southern slope is certainly driven by the peculiar geologic and tectonic structure and in particular by the presence of a heavily fractured bedrock in the frontal band of the local thrust (benko & stead, 1998; stead & wolter, 2015). other factors have played a role in the progressive decay of the frictional strengths of the joint surfaces, like alpine climate and climate changes and related erosional processes, groundwater flow and karst dissolution, along with seismicity. glacial erosion and possible debuttressing have weakened the rock masses and changed stresses in the slope by unloading. the influence of past and current seismicity is not known, in terms of major co-seismic events, as only relatively small rock falls events have been recorded. nevertheless, earthquakes may have affected the strength of steep and fractured rock slopes. in conclusion, the combination of individual predisposing factors appears to be more relevant than specific triggers in driving slope processes affecting the m. salta southern slope. references benko b., stead d. (1998) the frank slide: a reexamination of the failure mechanism. canadian geotechnical journal, 35, 299-31. doi: 10.1139/t98-005 doglioni c. (1992) relationships between mesozoic extensional tectonics, stratigraphy and alpine inversion in the southern alps. eclogae geol. helv., 85(1), 105-126. dykes a.p., bromhead e.n., hosseyni s.m., ibsen m. (2013) a geomorphological reconnaissance of structurally-controlled landslides in the dolomites. in genevois r., prestininzi a. (eds) international conference on vajont 1963-2013: thoughts and analyses after 50 years since the catastrophic landslide. italian journal of engineering geology and environment, book series no.6. sapienza università editrice, rome, 129-136. doi:10.4408/ijege.2013-06.b-10 esposito c., sánchez cabanillas b., bozzano f. (2015) new data and interpretation of the huge clastic deposit of “la pineda hill” (vajont valley, northern italy). rend. online soc. geol. it., 35, 117-120. doi: 10.3301/rol.2015.78 evans s.g., hungr o. (1993) the assessment of rockfall hazard at the base of talus slopes. canadian geotechnical journal, 30, 620-636. doi: 10.1139/t93-054 ghirotti m. (1995) l’antica frana del m. borgà e primi risultati del monitoraggio dell’area di prà del salta (casso, pn). quad. geologia applicata, 1, 123130, pitagora editrice, bologna. ghirotti m., masetti d., massironi m., oddone e., sapigni m., zampieri d., wolter a. (2013) the 1963 vajont landslide (northeast alps, italy): post 163 one of the hazardous neighbours of the vajont landslide: the m. salta rock-block slide-rock fall valley, northern italy. geoinformatica, 13, 323337. doi: 10.1007/s10707-008-0071-2 wolter a., stead d., ward b.c., clague j.j., ghirotti m. (2016) engineering geomorphological characterisation of the vajont slide, italy, and a new interpretation of the chronology and evolution of the landslide. landslides, 13(5), 1067-1081. doi: 10.1007/s10346-015-0668-0 164 ghirotti m. et al. ms. received: july 27, 2020 revised: october 5, 2020 accepted: october 29, 2020 available online: november 30, 2020 amq abs pini et al palcom 155-159.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 155 159 quantitative reconstructions of quaternary climates using pollen: assumptions, numerical techniques and calibration datasets roberta pini 1, federica badino 1,2, mattia de amicis 3, giulia furlanetto 3, valter maggi 3, cesare ravazzi 1, francesca vallè 3 1 idpa cnr, res. group on vegetation, climate and human stratigraphy, laboratory of palynology and palaeoecology, milano, italy 2 university of bologna, dept. of cultural heritage, bologna, italy 3 dept. of environmental and earth sciences, university of milano bicocca, milano, italy corresponding author: r. pini <roberta.pini@idpa.cnr.it> abstract: pollen assemblages are increasingly used for quantitative reconstructions of past climate parameters. estimated temperatures and precipitations can be coupled with palaeoecological records to make their interpretation more robust. although the potential of numerical techniques is suggested by published and ongoing researches, improvements in the calibration datasets used to compare fossil and modern pollen spectra are needed. current limitations within the european modern pollen database concerning data quality and density are discussed. attention is given to altitudinal training sets of modern pollen rain vegetation climate terrain parameters, allowing a better understanding of pollen dispersal and deposition across elevational gradients. keywords: quaternary, northern italy, climate, pollen, quantitative reconstructions, altitudinal training sets 1. introduction pollen is used since the early xxth century as a tool to reconstruct vegetation and environments and their reaction to climate change and human pressure. the potential of pollen spectra as descriptors of past climate conditions is gaining increasing interest in the quaternary community (juggins and birks, 2012). new pollen records are produced every year from different ecological and climatic regions, thanks to the exceptional fossilization potential of palynomorphs and to the possibility of identifying them with high taxonomic resolution. coupling traditional pollen-stratigraphical researches with quantitative climate reconstructions based on the same compilation of data can indeed provide new hints for the interpretation of palaeoecological records and improve our understanding of man-environment interactions. statistical approaches based on regression calibration and modern analogues were developed for different types of microscopic biological remains (chironomid: eggermont and heiri, 2011; chrysophytes: kamenik and schmidt, 2005; cladocera: brodersen et al., 1998; diatoms: birks et al., 1990; pollen: see references cited in seppä et al., 2004) and they are currently used for quantitative estimations of past temperatures, precipitation, chemical and trophic state of water bodies. to do so, the development of transfer functions connecting modern calibration data sets and fossil ones is needed. as far as pollen is concerned, the european modern pollen database (empd; davis et al., 2013) is used as source for statistically-based comparisons between fossil and modern pollen spectra. although the relevance of this dataset is undeniable, several points need to be fixed in order to provide the eurasian pollencommunity with an ecologically sound and complete tool for palaeoclimate reconstructions. this contribution will focus on principles and techniques of quantitative climate reconstructions using pollen, the relevance of such reconstructions for our understanding of past ecological systems and on advantages/ disadvantages of current calibration datasets. 2. methods: a short review on principles and techniques of quantitative climate reconstructions based on pollen some biological assumptions support the use of pollen as a proxy of climate. as regional vegetation is influenced by climate, we might expect that the climate variability plays a relevant role not only in the extent of vegetation communities and their composition, but also on pollen productivity and deposition modes. the validity of this hypothesis was checked by several authors (sjögren et al., 2006 and references therein). pollen proportions and pollen accumulation rates (par) can indeed be considered as a response of vegetation and depositional processes to climate conditions. before using pollen as climate descriptor, a few requirements need to be met: (1) a calibration training set of pollen deposition and associated temperature/precipitation data must be available for a given climate gradient; (2) the relationships between pollen descriptors and modern climate parameters must be modelled; (3) quantitative climate parameters can be estimated through the application of the model (transfer function) to fossil pollen data. requirement #1 may be fulfilled by subsets extracted from the european modern pollen database (fig. 1). requirements #2 and #3 are tackled through numerical techniques of regression-calibration and search for https://doi.org/10.26382/aiqua.2018.aiquaconference modern analogues, namely wa (weighted averaging), wa-pls (weighted-averaging partial least square) and mat (modern analogue technique) (fig. 2). 3. the european modern pollen database: its content and some main limitations more than 4200 modern pollen samples with associated climate data are stored in the current empd version (fig. 1). samples cover a large part of eurasia, from portugal to siberia, from fennoscandia to the near east; a large variety of ecosystems is represented. the effort done by davis et al. (2013) to make this database available to the scientific community is impressive and no progresses in the direction of using pollen as a proxy of climate could be possible without this calibration set. nevertheless, the empd has some limitations; they do not hamper its use, although refinements would greatly increase its potential. the main disadvantages are here listed: 1) uneven quality of the taxonomic identification of pollen grains. unfortunately there is no common rule on the degree to which palynologists identify pollen grains; this results in a great issue when pollen spectra counted by hundreds of different analysts are gathered in a common dataset. just two examples: keeping the pollen of climate-sensitive timberline species such as pinus cembra separated from pinus sylvestris/mugo and alnus viridis from alnus glutinosa/incana can greatly enhance the quality of pollen -reconstructed climate series in the high-altitude alps (furlanetto et al., unpublished data). at an alpine scale, only 68 modern pollen spectra out of the available 270 comply these rules. 2) uneven spatial and temporal distribution of the sampling sites. fig. 1 shows that, despite the wide latitudinal and longitudinal extents covered by the empd, large areas still have poor or no sample coverage. this is the case, for example, of the area between the balkans and the carpathians, the ukrainian plains, western siberia, the mediterranean islands and the po plain. some of the ecosystems represented in these areas (garrigue, steppes, foreststeppe ecotones and taiga) are not sufficiently sampled in the empd, resulting in an incomplete representation of the ecological gradient of several plant 156 fig. 1 geographical extent of the european modern pollen database (empd: davis et al., 2013). red dots indicate the location of the 4270 sampling sites superimposed on the spatial distribution of global ecological zones (gez) proposed by the global forest resources assessments (grfa) of fao (http://www.fao.org/forest-resources-assessment/remote-sensing/global-ecological-zones-gez/en/). metadata, as well as pollen and climate data associated to each empd site shown in the map can be downloaded at http:// www.europeanpollendatabase.net/wiki/doku.php?id=empd_download_database. pini r. et al. 157 species. 3) data stored in the empd do not provide a consistent picture of pollen dispersal along mountain altitudinal gradients of eurasia, given the limited number of samples collected from the same catchment trunk. the issue of long-distance transport of pollen is well known to researchers working in mountain areas and it must be carefully considered when using pollen data for palaeoenvironmental reconstruction and inferences on past climate. to overcome this issue, the development of local altitudinal training sets is needed (see section 4). 4) variations of pollen deposition throughout sedimentary processes and the effects of human activities on the accumulation of microbiological particles are poorly accounted by empd sampling. long-distance floated and airborne associations of alluvial, marine and aeolian environments are almost not represented quantitative climate reconstructions using pollen fig. 2 schematic representations of the materials and methods involved in a quantitative climate reconstruction based on pollen grains (redrawn and modified after juggins and birks 2012). modern pollen deposition can be analyzed in different typologies of samples (mosses, core tops, artificial pollen traps, soil, litter): these data are accompanied by information on site-specific temperature and precipitation. the calibration dataset used for the development of paleoclimate transfer functions is composed by thousand of modern sites. transfer functions are then applied to fossil pollen spectra for the reconstruction of past climate parameters. in the empd. those issues have to be carefully considered when working in archaeological sites and cultural landscapes. 4. altitudinal training sets of modern pollen and climate for proxy calibration along mountain valleys we recently developed two calibration sets of modern pollen rain vegetation cover climate data terrain parameters in the western and central alps (la thuile and brembana valleys, respectively; badino, 2016 and furlanetto et al., submitted); in the same valleys palaeoecological researches on high-altitude mires were in progress. at each sampling site we carried out vegetation surveys and monitoring of modern pollen deposition through the analysis of moss samples. site-specific temperature and precipitation series, covering the 19512015 period, were reconstructed for each sampling site by means of the anomaly method (new et al., 2000; mitchell and jones, 2005) as described in brunetti et al. (2012). the aim of such big efforts was to obtain valleyspecific proxies’ calibration along altitudinal transects and to improve our knowledge on the relationships between the selected parameters. data collected with our two alpine calibration sets were used, along with the empd data, for temperature and precipitation reconstructions of holocene pollen records from two high-altitude sites in the continental western alps (badino et al., 2018) and in the oceanic external alpine chains of lombardy (furlanetto et al., in progress). pollen-inferred climate reconstructions show a significant comparison with independent proxies of climate such as the extent of some alpine glaciers (holzhauser et al., 2005; le roy et al., 2015), pollen and chironomid-inferred temperature records from the swiss and austrian alps (wick et al., 2003; ilyashuk et al., 2011), isotopic records from alpine speleothems (luetscher et al., 2011; fohlmeister et al., 2013) and the sequence of cold periods in the alps (zoller et al., 1966; patzelt and bortenschlager, 1973). 5. conclusion similarly to other biological remains, pollen can be used for quantitative reconstructions of past temperatures and precipitations. in the past decade, progresses were recorded in the numerical techniques employed for this purpose and in the digital platforms where specific software packages are executed. for robust climate reconstructions, a thorough knowledge of the relationships between modern pollen deposition, temperature and precipitation is mandatory. the availability of continental-wide calibration sets (european modern pollen database empd, north american pollen database napd, east asian pollen database eapd, african pollen database apd, etc.) is acknowledged. improvements in the quality and quantity of data stored in these datasets are needed, to increase the performance of the modern-to-fossil transfer functions for past climate reconstructions. acknowledgements this research is partially funded by the cnr-dta project of interest nextdata, a national system for the retrieval, storage, access and diffusion of environmental and climate data from mountain and marine areas (www.nextdataproject.it). references badino f. (2016) holocene vegetation and climate variability as recorded in high-altitude mires (western italian alps). unpublished phd thesis in environmental sciences, univ. milano-bicocca, milano, italy, pp. 145. badino f., ravazzi c., valle' f., pini r., aceti a., brunetti m., champvillair e., maggi v., maspero f., perego r., orombelli g. (2018) 8800 years of high-altitude vegetation and climate history at the rutor glacier foreland, italian alps. evidence of middle holocene timberline rise and glacier contraction. quaternary science reviews, 185, 41-68. birks h.j.b, line j.m., juggins s., stevenson a.c., ter braak, c.j.f (1990) diatoms and ph reconstruction. philosophical transactions of the royal society of london series b, 327, 263-78 brodersen k.p., whiteside m.c., lindegaard c. (1998) reconstruction of trophic state in danish lakes using subfossil chydorid (cladocera) assemblages. can. j. fish. aquat. sci., 55, 1093-1103. brunetti m., lentini g., maugeri m., nanni t., simolo c., spinoni j. (2012) projecting north eastern italy temperature and precipitation secular records onto a high-resolution grid. physics and chemistry of the earth, 40-41, 9-22. davis b.a.s., zanon m., collins m., mauri a., bakker j., barboni d., barthelmes a., beaudouin c., birks h.j.b., bjune a.e. et al. (2013) the european modern pollen database (empd) project. vegetation history and archaeobotany, 22, 521-530. eggermont h., heiri o. (2011) the chironomidtemperature relationship: expression in nature and palaeoenvironmental implications. biological reviews, 87, 430-456. fohlmeister j., vollweiler n., spötl c., mangini a. (2013) comnispa ii: update of a mid-european isotope climate record, 11 ka to present. the holocene, 23 (5), 749-754. holzhauser h., magny m., zumbühl h.j. (2005) glacier and lake-level variations in west-central europe over the last 3500 years. the holocene, 15 (6), 789-801. kamenik c., schmidt r. (2005) chrysophyte resting stages: a tool for reconstructing winter/spring climate from alpine lake sediments. boreas, 34. 477489. ilyashuk e.a., koinig k.a., heiri o., ilyashuk b.p., psenner r. (2011) holocene temperature variations at a high-altitude site in the eastern alps: a chironomid record from schwarzsee ob sölden, austria. quaternary science reviews, 30 (1), 176-191. juggins s., birks h.j.b. (2012) quantitative environmental reconstructions from biological data. in (birks et al., eds.): tracking environmental change using lake sediments. data handling and numerical 158 pini r. et al. techniques. chapter 14, springer, the nedertlands., 431-494. luetscher m., hoffmann d.l., frisia s., spötl c. (2011) holocene glacier history from alpine speleothems, milchbach cave, switzerland. earth and planetary science letters, 302 (1), 95-106. mitchell t.d., jones p.d. (2005) an improved method of constructing a database of monthly climate observations and associated high-resolution grids. international journal of climatology, 25, 693-712. new m., hulme m., jones p. (2000) representing twentieth-century space-time climate variability. part ii: development of 1901-96 monthly grids of terrestrial surface climate. journal of climate, 13, 2217-2238. sjögren p., van leeuwen j.f.n., van der knaap w.o., van der borg k. (2006) the effects of climate variability on pollen productivity, ad 1975-2000 recorded in a sphagnum peat hummock. the holocene, 16(2), 277-286. wick l., van leeuwen j.f., van der knaap w.o., lotter a.f. (2003) holocene vegetation development in the catchment of sägistalsee (1935 m asl), a small lake in the swiss alps. journal of paleolimnology, 30 (3), 261-272. zoller h., schindler c., röthlisberger h. (1966) p o s t g l a z i a l e g l e t s c h e r s t ä n d e u n d klimaschwankungen im gotthardmassiv und vorderrheingebiet. verh. naturforsch. ges. basel, 77 (2), 97-164. 159 quantitative climate reconstructions using pollen ms. received: may 4, 2018 final text received: may 16, 2018 160 amq abs monegato ravazzi tepro 225-229.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 225 229 the late pleistocene multifold glaciation in the alps: updates and open questions giovanni monegato 1, cesare ravazzi 2 1 istituto di geoscienze e georisorse, cnr, padova, italy 2 istituto per la dinamica dei processi ambientali, cnr, milano, italy corresponding author: g. monegato <giovanni.monegato@igg.cnr.it> abstract: the stratigraphic record of late pleistocene glaciations in the alps is well defined for the last glacial maximum (lgm) thanks to recent chronological and stratigraphic studies. these allowed to compare the spread of the glaciers to the global climate models for the lgm, whereas, the amplitude of glacial advances in the pre-lgm late pleistocene needs further investigation in chronostratigraphic archives, with emphasis on the dynamics of alpine glaciers during cold stages mis5d, mis4, and the several mis3 stadials. in this perspective, the stratigraphic archives bearing finite ages close to the radiocarbon method limit could be tested for improvements of the available chronological methods. keywords: late pleistocene, alps, glaciations 1. introduction according to the isotopic record from ice-cores, the late pleistocene was marked by at least four major cold stages (mis5d, mis5b, mis4 and mis2, the latter culminating in the last glacial maximum, lgm). the global lgm is a climate-stratigraphic concept defined as the last period framed in the last glaciation when global ice sheets reached their maximum integrated volume, currently between 27 and 19 ka bp (clark et al., 2009) or 30 and 17 ka bp (lambeck et al., 2014). recent climate-models investigated the interaction among atmospheric circulation, oceanic circulation and ice-sheet waxing (e.g., beghin et al., 2015; liakka et al., 2016). first lgm proxy reconstructions in the alps allowed first validation of these models (luetscher et al., 2015). in the alps, recent stratigraphic investigations expanded the dataset of the late pleistocene glacial events, especially the time constrains for glacier spread during the lgm. the development of alpine valley glaciers during the pleistocene has been the topic of a large number of studies since the 19th century and especially after the milestone work by penck & brückner (1909), in which the multi-glaciation theory was illustrated. during the 20th century the application of this subdivision acted as a postulate, adopted in all the stratigraphic works within the alpine realm, including geological mapping. only after bowen (1978) and šibrava (1986) this subdivision was suggested to be abandoned and substituted by an array of stratigraphic approaches including allo-, chrono-, bio and isotopic stratigraphy. the development of dating methods in the last forty years improved the chronological assessment of glacial units, especially for those related to the lgm and those marked by a reverse paleomagnetic signal. 2. historical background in the alps, the last glacial cycle has been related to the würm glaciation (penck & brückner, 1909) and its three-phases subdivision formalized by reference sections and type localities of regional value in the austrian alps (chaline & jerz, 1984; see also spötl et al., 2013). this regional scheme distinguishes the “lower” (broadly encompassing the post-eemian mis5), the “middle” (mis4 and 3) and the “upper” würm (mis 2). the designation of stratotypes and / or reference sections and type localities for continental units is prescribed by the international stratigraphic code currently in use (murphy and salvador, 1998). however, until recent times, the use of this alpine regional stratigraphy in correlating end-moraine systems was mostly supported by criteria based on field properties of weathering profiles. these field criteria were poorly checked by laboratory calibration analysis, while their chronological implications were poorly tested by independent dating methods. finally, most of the field weathering profile criteria failed the proof of geochronometric dating. indeed, several glacial bodies forming the italian end-moraine systems, identified by their weathering profiles, and classified into several distinct middle or late pleistocene “glaciations” (e.g. venzo, 1965; 1977; petrucci, 1970; bini & zuccoli, 2004) were resettled to the lgm whenever radiometric dating has been successfully applied (ravazzi et al., 2014; gianotti et al., 2015; monegato et al., 2017; ivy-ochs et al., in press). it turned out that the largest end-moraine systems, formed during the lgm at the italian fringe, consist of several acme moraine complexes staked by millennial climate events (monegato et al., 2017; see fig. 1). further investigation is needed in other large end-moraine systems including glacial units ascribed to middle pleistocene on the base of weathering profiles (e.g. the besnate allogroup in the ticino and https://doi.org/10.26382/aiqua.2018.aiquaconference adda rivers glacial systems, bini et al., 2004). 3. recent updates of the upper pleistocene units in the alps regarding the three subdivisions of the würm glaciation, in the austrian stratotype of baumkirchen the upper würm onset, marked by the advance of the inn glacier over the middle inn valley, was recently chronologically constrained at 32-33 ka cal bp (spötl et al., 2013). at the same site, the occurrence of lower-middle würm advances has been investigated in recent years (barrett et al., 2017). studies on lacustrine records around the alps yielded climatic and environmental information which show an overall agreement with glacier build-ups before lgm, i.e. during mis5d and mis4, but also mis3 stadials (drescher-schneider et al., 2000; 2007). the sedimentary traces of advances predating the upper würm are scattered and scarce in some sectors (fig. 1). in the austrian sector of the alps a few outcropping sections and core records document upper pleistocene pre-lgm glacial and glaciolacustrine deposits (starnberger et al., 2013; barrett et al., 2017). in the swiss sector of the alps the occurrence of three different advances was highlighted in the definition of birrfeld glaciation (e.g., preusser et al., 2011; buechi et al., 2017) through osl and radiocarbon dating on glaciofluvial and glaciolacustrine deposits. as in the austrian part, the lower-middle würm advances were recognized in cores and stratigraphic sections generally buried by the lgm deposits, whereas moraines of relevant age were not documented in piedmont amphitheaters. on the italian side of the alps, pre-lgm cold / continental phases are represented by subtle alluvial sediment piles in the late pleistocene lower plain successions (pini et al., 2009; hippe et al., 2018), suggesting a scarce sedimentary delivery from the mountains or, alternatively, that most of the deposits related to cold stages were stored within the valleys. in the friulian piedmont plain the valeriano creek succession, related 226 fig. 1 schematic overview of the temporal development of the extent of the glaciers from the alpine core massifs (pale blue) and external massifs (dark blue) compared to the stratigraphic ranges of important and well dated würm palaeoclimatic, sedimentary and palaeoenvironmental archives (vertical bars) in the alps and their foreland (see also mayr et al., 2017). western alps (in blue): 1) north grésivaudan (guiter et al., 2008), 2) les echets (de beaulieu & reille, 1984). northern alpine sector (in grey): 1) baumkerchen (spötl et al., 2013; barrett et al., 2017), 2) unteragenberg (starnberger et al., 2013), 3) gossau (preusser et al., 2003), 4) hopfgarten and kitzbüel (reitner & draxler, 2002), 5) nesseltalgraben (mayr et al., 2017), 6) samerberg (grüger, 1979), 7) thalgut (preusser & schlüchter, 2004), 8) mondsee (drescher-schneider, 2000), 9) niederweningen (dehnert et al., 2012), 10) füramoos (müller et al., 2003), 11) jammertal (müller, 2000). southern alpine sector (in red): 1) albeins (fliri, 1971), 2) spormaggiore (avanzini et al., 2012), 3) vilminore (unpublished data), 4) valeriano (monegato et al., 2010), 5) garda and tagliamento (monegato et al., 2007, 2017), 6) castelnovate (orombelli, 1986), 7) fimon (monegato et al., 2011), 8) casaletto ceredano (ravazzi et al., 2018), 9) piancada (hippe et al., 2018), 10) azzano decimo (pini et al., 2009). the stacked northern atlantic 18o record from benthic foraminifera and the marine isotope stages (mis; from lisiecki and raymo 2009) are shown for comparison. monegato g., ravazzi c. 227 to a small foothill catchment, shows gravel aggradation during the mis5d, and, after fine-grained deposition ascribed to mis5c-a, another coarse-grained unit occurs before 36.0±2.2 cal ka bp (monegato et al., 2010). similar situations, with ages close to the radiocarbon method limit, are reported for the ticino system in the alpine foreland (castelnovate site, orombelli, 1986). these sites indicate active aggradation of fluvial systems belonging to glaciated catchments at least during cold phases of mis3. 4. the lgm record and inferences on global circulation models the culminations occurring in the late würm are now commonly associated to the lgm thanks to a robust chronology available for several sector of the alps including end-moraine systems (e.g., monegato et al., 2007, 2017; ivy-ochs et al., 2008; ravazzi et al., 2012; federici et al., 2016) and the related outwash plains (fontana et al., 2010). the spread of the alpine glaciers reached its maximum at about 26-24 ka (fig. 1) in correspondence to the insolation minimum (laskar et al., 2004) and the greenland stadial 3 (andersen et al., 2006), considered to be the peak in global ice volume (hughes and gibbard, 2015). comparing the lgm development of alpine glaciers to the waxing of the boreal ice-sheets, it is interesting the in-phase relationship with the north american ice-sheet (nais) at 26-24 ka. according to the atmospheric circulation models (e.g., beghin et al., 2015; liakka et al., 2016) the topography of the nais controlled the circulation and the development of the european ice-sheets, including mountain glaciers (monegato et al., 2017). according to these models, during the mis5b and mis4 the european icesheet experienced a larger expansion towards the north, due to the lesser extension of the nais and the circulation track delivering moisture northwards. during these phases, the alps were mostly interested by westerlies and the glaciers of the western french alps likely reached sizes similar to the lgm ones. different circulation tracks could have meant changes in distribution of the precipitations in the alps, with consequence of spread of local glaciers, especially in the forealpine sector and the western french alps, where elevated plateaus could have developed large glaciers during prelgm cold phases. this possible large extension of glaciers in the western alps has been modeled by seguinot et al. 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(1977) i depositi quaternari e del neogene superiore nella bassa valle del piave da quero al montello e del paleopiave nella valle del soligo (treviso). memorie degli instituti mineralogia e geologia dell’università di padova, 30, 1-64. 229 alpine late pleistocene multifold glaciation ms. received: may 7, 2018 final text received: may 18, 2018 230 imp.principe_giannandrea ubsu e cartografia geologica: problemi e potenzialità di utilizzo delle unita' a limiti inconformi (ubsu) nell'interpretazione e nella rappresentazione cartografica dei depositi vulcanici quaternari l'esempio dei fogli n.ro 451 “melfi” e n.ro 452 “rionero in vulture” claudia principe1 & paolo giannandrea2 1istituto di geoscienze e georisorse, area della ricerca c.n.r. di pisa, <c.principe@igg.cnr.it> 2dipartimento di geologia e geofisica centro interdipartimentale di ricerca per la valutazione e mitigazione del rischio sismico e vulcanico, università degli studi di bari abstract: c. principe & p. giannandrea, ubsu inside geological mapping: the use of the unconformity bounded stratigraphic units in the chartography of the quaternary volcanic deposits the exemples of melfi (n. 451) and rionero (n.452) areas. by means of the use of the unconformity bounded stratigraphic units the sedimentary and volcanic stratigraphic successions outcropping in the area of mount vulture volcano (n.451 “melfi” and n.452 “rionero in vulture”) has been subdivided in synthematic units. unconformity use hallowed to define two supersynthems and five synthems. the synthematic subdivision over passed the limits of the chartographed area and make possible the correlations of deposits on a wider area. the clear and objective criteria on witch sybthematic units are based resulted in an improvement of geological significance and in the volcanological detail of the chartographed areas parole chiave: cartografia, depositi vulcanici, quaternario. keywords: geological mapping, volcanic deposits, quatenary. il quaternario italian journal of quaternary sciences 21(1a), 2008 61-68 introduzione le regole introdotte per la cartografia dei fogli della nuova carta geolgica d'italia alla scala 1:50.000 (la volpe et al. 1992), impongono per la cartografia del vulcanico le unità a limiti inconformi (ubsu) (salvador, 1987 & 1994). l'applicazione di questi principi cartografici ha, specie in un primo tempo, sollevato un vivace dibattito sulla validità delle unità sintematiche nel descrivere la storia eruttiva di un'area vulcanica, rispetto alle unità lito-stratigrafiche ed alle unità eruttive, più tradizionalmente usate. scopo di questa nota è rendere ragione della positiva esperienza degli autori nell'utilizzo delle ubsu per la cartografia dei depositi vulcanici presenti nei fogli n.ro 451 “melfi” e n.ro 452 “rionero in vulture” e per la comprensione della storia evolutiva del vulcano di monte vulture e dei suoi rapporti con i bacini lacustri e fluvio-lacustri che ad esso sono associati. all'interno di questi due fogli a scala 1: 50.000 affiora il 95% dei depositi del vulcano monte vulture e i depositi epiclastici dei bacini lacustri e fluviolacustri di melfi, atella e venosa. la varietà degli ambienti genetici e di sedimentazione presenti in questa piccola area, ed il lungo intervallo di età invece coperto dall'attività vulcanica, hanno rappresentato un ottimo banco di prova per la rigida applicazione alle vulcaniti delle unità a limiti inconformi, come definite da salvador (1987 & 1994). la presenza all'interno dei due fogli di una gran varietà di litotipi vulcanici in facies di deposizione sia primaria che secondaria e di un bilanciato quantitativo di depositi non solo vulcanici ma anche sedimentari, ha permesso, meglio forse che in altre realtà cartografiche tutte chiuse “dentro” edifici vulcanici di maggiori dimensioni del monte vulture, di verificare come le superfici di discontinuità, non solo superano i limiti litologici fra vulcanico e sedimentario, ma portano effettivamente alla definizione di unità cartografiche “obbiettive e non interpretative” come dichiarato da salvador (1987 & 1994), in grado di essere rapportate con altre realtà geologiche limitrofe e di inserirsi in altre stratigrafie mantenendo compiutamente il loro rango ed il loro significato geologico. in altre parole, parafrasando salvador (1987 & 1994): questo tipo di approccio ha rivelato possedere l'enorme vantaggio, rispetto ad altri più interpretativi, di definire delle unità stratigrafiche “naturali” (o forse sarebbe più corretto dire “geologiche”), frutto di un approccio più completo, più chiaro e più pragmatico alla stratigrafia dei depositi, che ha condotto ad una analisi più descrittiva e più lucida della storia geologica di questa area vulcanica. un'unità stratigrafica a limiti inconformi è definita come un corpo roccioso delimitato a tetto ed a letto da una ben descrivibile, significativa e dimostrabile, discontinuità nella successione stratigrafica, preferibilmente visibile a carattere regionale o interregionale (salvador, 1987 & 1994). un'unità a limiti inconformi è inoltre per sua natura sempre, in maggiore o minore misura, diacrona, (salvador, 1987 & 1994). il corretto utilizzo di questi due semplici criteri comporta che nella cartografia ubsu del vulcanico non possono essere considerate unità sintematiche i singoli corpi vulcanici (esistono per questo facies e litosomi) ed impedisce l'uso come unità cartografica fondamentale delle unità lito-stratigrafiche, relegandole al ruolo di segmenti di un 62 c. principe & p. giannandrea più vasto sintema. la stessa sorte spetta alle “unità eruttive” ed alle “unità crono-stratigrafiche”, che non possono essere assimilate ad unità a limiti inconformi; le prime perché non considerano i depositi epiclastici, le seconde per la tipologia del loro limite. il fatto che “le isocrone non possono oltrepassare le superfici di discontinuità” (salvador,1987 & 1994) impedisce anche l'uso nella cartografia del vulcanico di alcuni “deus ex machina”, talvolta usati nella passata cartografia, come i cosiddetti “ascensori”; cioè la costruzione di unità che raccolgono oggetti simili, ma presenti a diversi livelli stratigrafici. secondo questa regola, ad esempio, non ha validità di sintema un'unità costituita da numerosi coni di scorie morfologicamente indistinguibili ma aventi età diverse o addirittura di età ignota, intercalati a più livelli in una successione stratigrafica nota. i depositi vulcanici sono legati ad eventi geologici di breve durata, con eruzioni che durano pochi giorni, mesi, qualche volta anni, mentre una singola fase d'attività vulcanica può essere separata dalla successiva da lunghi periodi di quiescenza, durante i quali prevalgono le azioni erosive e la formazione di paleosuoli ed epiclastiti. queste discontinuità segnano il ritmo di vita e la storia evolutiva del vulcano. nei bacini sedimentari limitrofi alle aree vulcaniche, invece, i processi di sedimentazione sono più continui nel tempo, ed in larga parte sono alimentati dall'erosione e rideposizione dei depositi vulcanici primari. all'interno di una sequenza di questo tipo, eventuali episodi eruttivi sufficientemente estesi, di provenienza anche distale, possono costituire dei validi markers stratigrafici. nelle aree vulcaniche i limiti stratigrafici delle unità ubsu saranno quindi individuati da superfici erosive, paleosuoli e depositi epiclastici intercalati a depositi primari, mentre nei bacini sedimentari contigui tali limiti corrispondono a superfici d'erosione all'interno di una sequenza epiclastica, a discordanze legate ad effetti della tettonica ed a variazioni eustatiche del livello del mare. queste ultime, se riconosciute anche sulle vulcaniti, consentono di individuare discontinuità tracciabili a grande scala che racchiudono unità stratigrafiche complesse in cui possono coesistere, in rapporto di eteropia di facies, terreni molto differenti sia vulcanici sia sedimentari, di ambiente continentale e marino. e' evidente quindi che, per associare alle differenti fasi eruttive delle variazioni geologiche di valenza più generale, lo studio stratigrafico, sedimentologico e tettonico delle diverse aree da cartografare deve essere indirizzato ad individuare discontinuità che oltrepassino i limiti del singolo edificio vulcanico e del singolo bacino sedimentario. questo genere di discontinuità, individua le unità sintematiche. per gestire una siffatta materia occorre un approccio cartografico multidisciplinare ed integrato. di fatto la stretta collaborazione fra vulcanologi, geologi del sedimentario, stratigrafi, strutturalisti, geomorfologi e geochimici venuta ad attuarsi nel corso del rilievo carg dei fogli n. 451 e n. 452, ha largamente superato l'obbiettivo della produzione degli elaborati cartografici al 50.000, ed ha portato a compiere un notevole balzo in avanti nella comprensione della storia geologica di questa regione vulcanica e della storia evolutiva del vulcano di monte vulture (principe & giannandrea, 2002 & 2006; giannandrea, 2004; schiattarella et al., 2005; giannandrea, 2006a & b; giannandrea et al., 2004 & 2006; principe, 2006). unita' stratigrafiche a limiti inconformi i fogli n. 451 e n. 452 racchiudono la quasi totalità dei prodotti vulcanici del monte vulture, l'unico vulcano quaternario italiano ubicato sul fronte esterno della catena appenninica, ed ampie aree dei bacini sedimentari ad esso associati (fig. 1). il foglio n. 452 “rionero in vulture” include nella sua metà nord-orientale anche terreni della fossa bradanica, mentre il foglio n. 451 “melfi”, racchiude aree di catena e terreni del bacino plio-pleistocenico dell'ofanto (fig. 1). i prodotti vulcanici di monte vulture, con una età compresa tra circa 740 ka e 140 ka (fig. 2) (buettner et al., 2006) si impostano su una paleogeografia alluvionale (giannandrea et al., 2004 & 2006) e sono in rapporto di eteropia di facies con i sedimenti epiclastici e clastici, fluviolacustri dei bacini di melfi, atella e venosa ed alluvionali della fiumara dell'arcidiaconata e del fiume ofanto (fig. 1). tutti questi terreni poggiano con un rapporto di discordanza angolare sulle coltri appenniniche e sui sedimenti del margine orientale del bacino dell'ofanto (fig. 1). solo i terreni del bacino di venosa, costituendo il riempimento di una paleovalle sviluppata in gran parte nelle aree della fossa bradanica, sono discontinui sui sedimenti di colmamento dell'avanfossa (fig. 1). l'area d'affioramento delle vulcaniti è attraversata da faglie ad andamento antiappenninico di importanza litosferica che nel pleistocene medio sono state responsabili del sollevamento della fossa bradanica e dell'avampaese apulo (ciaranfi et al., 1983; pieri et al., 1994; doglioni et al., 1996), causando variazioni del reticolo idrografico del bacino di venosa (piccarreta & ricchetti, 1970; segre, 1978; boenzi et al., 1987; ciaranfi et al., 1983), ed hanno gestito il complesso processo di risalita dei magmi che hanno alimentato l'attività vulcanica (schiattarella et al., 2005; principe, 2006). la successione delle vulcaniti presenta numerose discontinuità stratigrafiche non dovute alle modalità di messa in posto dei singoli depositi primari, e rappresentate da vistose superfici erosive, paleosuoli e depositi epicalstici (che spesso rappresentano variabili della stessa discontinuità e separano successioni discordanti e/o disconformi); talora queste discontinuità fossilizzano strutture tettoniche ed a volte la loro estensione laterale non supera quella dell'affioramento in cui sono osservabili. in quest'ultimo caso, in accordo con i criteri sopra esposti, esse non sono state prese in considerazione nella definizione delle unità ubsu cartografabili. in base ai criteri d'accettabilità precedentemente accennati sono stati individuati in tutta la successione primaria del monte vulture cinque sintemi (foggianello, barile, melfi, valle dei grigi fosso del corbo e laghi di monticchio) (fig. 2), definiti da discontinuità sempre visibili e tracciabili almeno su tutta l'area di distribuzione dei relativi depositi. all'interno dei sintemi sono stati definiti più sub-sintemi (fig. 2), costituiti da singoli corpi geologici o limitate successioni di sedimentazione aventi per limite discontinuità minori ma ancora estese all'intera area d'affioramento dei relativi depositi. i sintemi sono stati raggruppati in due supersintemi (monte vulture e monticchio). il limite che separa questi due supersintemi coincide con un importante paleosuolo (marker m18; la volpe & principe, 1991) che continua ad essere tracciabile anche al di fuori dei terreni vulcanici (fig. 2). il paleosuolo m18 fossilizza una fase tettonica regionale (schiattarella et al., 2005) a seguito della quale si è verificato, probabilmente in più tempi, il ribassamento della metà meridionale del vulcano ed il collasso del suo quarto sud-occidentale (la volpe et al., 1984; la volpe & principe, 1994; ciccacci et al., 1999; giannandrea, et al., 2004 & 2006). questo limite fra i due supersintemi corrisponde anche: ad un importante iatus nell'attività vulcanica, successivo alla messa in posto del sintema di melfi, ad un cambiamento climatico verso un clima più caldo e più umido (bonadonna et al., 1998) e ad un deciso cambio di stile eruttivo, che nel successivo supersintema si esprime non attraverso l'attività di un limitato numero di apparati poligenici ubicati in un intorno della stessa zona di alimentazione, come avvenuto nel supersintema di monte vulture, ma con la creazione di una serie di piccoli centri eruttivi, ubicati in coincidenza delle principali strutture fragili, e talora fuori dell'intera area di distribuzione delle vulcaniti deposte nel corso del precedente supersintema. questi centri a differenza di quelli caratterizzanti il precedente supersintema hanno spesso carattere diatremico (stoppa & principe, 1998) e vedono il costante coinvolgimento di magmi di natura profonda e la presenza di noduli mantellici (stoppa et al., 2006). nel supersintema di monte vulture infine la tettonica prevalente è impostata su strutture ad andamento n30° 40°, con faglie connesse all'importante elemento tettonico regionale noto come “linea del vulture” (fig. 1). durante la messa in posto dei depositi facenti capo al supersintema di monticchio si hanno evidenze dell'atti63ubsu e cartografia geologica: problemi e potenzialità... vazione anche di faglie regionali ad andamento e-o e n120° (schiattarella et al., 2005). il supersintema di monte vulture comprende i sintemi di foggianello, barile e melfi, mentre il supersintema di monticchio comprende i sintemi di valle dei grigi fosso del corbo e dei laghi di monticchio (fig. 2). il limite che separa il sintema di foggianello da quello di barile è individuato da una superficie erosiva, da depositi epiclastici, e dalla formazione di una caldera. una superficie erosiva segna la base del sintema di melfi, mentre il limite che separa il sintema di valle dei grigi fosso del corbo da quello dei laghi di monticchio, è un paleosuolo. nella legenda delle unità cartografate (giannandrea, et al., 2004 & 2006), all'interno dello stesso sintema sono presenti sia unità vulcaniche primarie, che unità epiclastiche ed unità sedimentarie. alcuni sub-sintemi, tutti quelli per i quali la presenza di una chiara superficie di discordanza lo imponeva, sono costituiti da un unico corpo vulcanico (ad esempio il duomo di toppo san paolo); altri, come ad esempio i piccoli centri secondari presenti nella successione di vulture -san michele (fontana dei preti, serra di lupo e toppo sant'agata), fanno invece parte integrante di sub-sintemi più complessi. all'interno dei sintemi e/o dei sub-sintemi sono stati individuati dei membri (intesi come insiemi omogenei di depositi aventi caratteristiche litologiche ben definite e diverse, ma non separati da superfici di discontinuità ben tracciabili) solo nel caso delle due successioni a e b del sub-sintema di fig. 1 area d'affioramento delle vulcaniti del monte vulture e dei depositi epiclastici sedimentati nei bacini ad esso limitrofi. nel riquadro carta geologica schematica dell'italia meridionale, con l'ubicazione dell'area di affioramento delle vulcaniti del monte vulture e gli areali dei fogli della nuova carta geologica d'italia (carg), n. 451 “melfi” e n. 452 “rionero in vulture”. areal distribution of vulture volcanics and epiclastites. at left, geological sketch map of the area of interest with the indication of the carthographic unit 451 “melfi” and 452 “rionero”. 64 fig. 2 schema stratigrafico delle unità sintematiche cartografate al monte vulture e nei bacini idrografici del fiume ofanto e della fiumara di venosa. (1) età radiometrica da buettner et al, 2006. stratigraphical sketch of the synthematic chartographic units of mount vulture and hydrographical sedimentary basins of ofanto and venosa rivers. (1) radiometric age (from buettner et al, 2006). rionero (giannandrea, et al., 2004 & 2006). non sono state definite unità litologiche, ma le litologie (lave, travertini, etc..) sono state cartografate attraverso l'inserimento in carta di soprassegni. attraverso i soprassegni e l'inserimento di pedici nella legenda sono state identificate anche le varie facies deposizionali (depositi di caduta o di flusso, depositi lacustri, etc.). in questo modo si è evitata l'inutile proliferazione di colori e di c. principe & p. giannandrea caselle, ma allo stesso tempo è stata preservata l'informazione sulla tipologia dei depositi e quindi anche il legame fra il vecchio ed il nuovo modo di fare cartografia geologica, mantenendo la leggibilità dell'informazione pregressa, quale per esempio quella della vecchia carta essenzialmente litologica di hieke merlin et al. (1967). il sintema di foggianello (fig. 2) è l'unità cartografata stratigraficamente più bassa e comprende i sub-sintemi della spinoritola, di campanile e di fara d'olivo. il sub-sintema della spinoritola è costituito prevalentemente da conglomerati alluvionali e dai filoni trachitici ad haüyna affioranti in località la spinoritola (fig. 1). il sub-sintema di campanile comprende depositi esclusivamente vulcanici, sia di caduta sia derivanti da flussi piroclastici. al sub-sintema di fara d'olivo sono infine riferiti i depositi ignimbritici a composizione trachifonolitica, riconosciuti primieramente da crisci et al. (1983) ed affioranti principalmente alla periferia del vulcano, la formazione di una caldera (giannandrea, et al., 2004 & 2006) verificatasi dopo l'eruzione delle coltri ignimbritiche ed alcuni metri di depositi epiclastici di ambiente alluvionale presenti a tetto delle ignimbriti. nel sintema di barile sono compresi quattro subsintemi. la base dell'unità è il sub-sintema di toppo san paolo composto da un duomo fonolitico (hieke merlin, 1967; de fino et al, 1982 & 1986) affiorante in un'area ristretta a nord di rapolla (fig. 1), che attraversa tutta la precedente successione ed è ricoperto da piroclastiti di caduta e subordinatamente di flusso del sovrastante sub-sintema di rionero (giannandrea et al., 2004 & 2006). il successivo sub-sintema di vulture san michele comprende una spessa successione di prodotti (lave, depositi di flusso concentrato e diluito, con subordinati strati di cenere e lapilli di caduta) che nell'insieme costituiscono l'attuale rilievo morfologico di monte vulture (la volpe et al., 1988; la volpe & principe,1989 & 1991). il sub-sintema di ventaruolo, che chiude la serie di prodotti riferiti al sintema di barile, comprende depositi sia di caduta che di flusso concentrato (guest j.e., et al., 1988) e coincide con una fase distruttiva denunciata dalla formazione di larghi crateri nella zona sommitale dell'edificio vulcanico e dalla messa in posto di depositi dai vistosi caratteri freatomagmatici (giannandrea et al., 2004 & 2006). nel sintema di melfi (fig. 2) sono raggruppate le lave haüynititiche (hieke merlin, 1967) dei sub-sintemi del castello di melfi e di piano di croce, i depositi epiclastici, in facies alluvionale e palustre, del sub-sintema di piano del gaudo e spessi depositi di travertino affioranti lungo la fiumara dell'arcidaconata, distinti come sub-sintema di losagne arcidiaconata (giannandrea et al., 2004 & 2006). il supersintema di monticchio (fig. 2) raggruppa i prodotti vulcanici emessi da numerosi piccoli centri (identificati come sub-sintemi) distribuiti sia su faglie orientate in direzione n30°-40° e raggruppati nel sintema della valle dei grigi fosso del corbo (subsintemi di masseria di cuscito, imbandina e case lopes), che su faglie in direzione n120° e e-o raggruppati nel sintema di monticchio (sub-sintemi di casa rossa, piano comune, lago grande, lago piccolo e serra di bràida) (giannandrea et al., 2004 & 2006). uscendo dall'areale occupato dall'edificio vulcanico e dall'areale di distribuzione in facies primaria dei suoi depositi, si entra nelle valli della fiumara di venosa (giannandrea, 2006a e b) e del fiume ofanto (giannandrea, 2004) dove in aree distali al vulture è stato possibile riconoscere dei depositi primari riconducibili ad alcune delle sue eruzioni più voluminose (depositi di flusso piroclastico e di caduta correlabili con le coltri ignimbritiche di fara d'olivo e depositi di flusso e, più spesso, di caduta facenti parte del sintema di barile) intercalati a sedimenti alluvionali e a luoghi lacustri, terrazzati. tali terrazzi, sono stati correlati mediante profili morfologici longitudinali rettificati, tracciati lungo i fondovalli dei due fiumi. la correlazione delle unità terrazzate a quelle del monte vulture ha interessato solo i livelli gerarchici di sintema e di supersintema (fig. 2) e non i sub-sintemi. difatti nell'operare la correlazione su vaste aree è stata riscontrata una parziale sovrapposizione fra i sub-sintemi ed i litosomi, questi ultimi intesi come edifici o periodi d'attività vulcanica. conclusioni la descrizione oggettiva dei limiti e delle loro caratteristiche è alla base della definizione delle unità stratigrafiche a limiti inconformi. in questo la cartografia del vulcanico non ha motivo per discostarsi dalla cartografia d'altri ambienti di sedimentazione. l'utilizzo delle ubsu non preclude o limita in alcun modo l'informazione sui singoli eventi eruttivi né sulla litologia dei depositi vulcanici. la cartografia sintematica del vulcanico, del monte vulture in questo caso specifico, beneficia invece rispetto ad altri tipi di cartografia d'elementi geologici obbiettivi, evidenza di processi che molto difficilmente possono non avere avuto un ruolo importante nella ricostruzione della storia evolutiva di un vulcano. questi elementi si aggiungono al mero quadro stratigrafico, favorendo l'identificazione d'importanti eventi geologici (stasi, erosioni, cambiamenti climatici, etc.) e diventano evidenze cartografiche dell'evoluzione paleogeografia, delle periodicizzazioni dell'attività vulcanica, degli eventi tettonici e vulcanotettonici. la gerarchizzazione dei limiti consente inoltre di distinguere episodi d'attività di interesse solo stratigrafico da eventi legati a fatti geologici regionali e di maggiore importanza nella ricostruzione dell'evoluzione del vulcanismo. lo studio al monte vulture dei bacini epiclastici associati alle vulcaniti primarie, infine, ha messo in luce come una verifica della corretta attribuzione gerarchica dei limiti tracciati su vulcani che si situano in aree continentali, può essere fatta usando i limitrofi bacini sedimentari. difatti, la giustezza della suddivisione della serie vulcanica primaria in due supersintemi (monte vulture e monticchio), operata sul vulcano, è stata confermata dal ritrovamento nei bacini sedimentari limitrofi al vulture, di una fase di sollevamento regionale successiva alla fase di sedimentazione della porzione superiore di queste epiclastiti, a partire dallo stesso livello stratigrafico riconosciuto come limite di supersintema sul vulcanico. il limite tracciato sul vulcanico in facies primaria ha mantenuto quindi la sua validità anche al di fuori dell'ambiente di sedimentazione in cui è stato definito, ed è stato possibile estenderlo su scala regionale, come espressamente richiesto dalla normativa ubsu per un limite di supersintema. 65ubsu e cartografia geologica: problemi e potenzialità... riferimenti bibliografici boenzi f., la volpe l. & rapisardi l. 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(1986) cronologia 39ar / 40ar del complesso vulcanico del monte vulture. rend. simp, 41, 146-147. ms. ricevuto il 2 aprile 2008 testo definitivo ricevuto il 17 aprile 2008 ms. received: april 2, 2008 final text received: april 17, 2008 67ubsu e cartografia geologica: problemi e potenzialità... microsoft word 00_indice_06lm.docx il quaternario it issn 039-3356 italian journal of quaternary sciences 24 (2), 2011 171-178 il cranio di stephanorhinus hemitoechus (falconer, 1859) di fosso malafede (vitinia, roma) con note sulla prima presenza della specie in italia luca pandolfi dipartimento di scienze della terra, università sapienza, roma dipartimento di scienze geologiche università degli studi roma tre, roma corresponding author: <lpandolfi@uniroma3.it> riassunto: l. pandolfi, il cranio di stephanorhinus hemitoechus (falconer, 1859) di fosso malafede (vitinia, roma) con note sulla prima presenza della specie in italia. in questo lavoro viene descritto un cranio di rinoceronte rinvenuto nei depositi fluviali nei pressi di fosso malafede (vitinia, roma, italia centrale) e conservato nel museo di paleontologia della sapienza, università di roma. l’analisi morfo-comparativa condotta sul cranio ha permesso di attribuire lo stesso alla specie stephanorhinus hemitoechus. il cranio presenta i caratteri tipici della specie, quali, una cresta occipitale relativamente molto sporgente verso l’indietro, la serie dentaria avanzata e l’incisura nasale arretrata. inoltre, sulla base dell’usura dentaria, il cranio viene riferito ad un individuo di età molto avanzata, di circa 30-36 anni. s. hemitoechus descritto per la prima volta in gran bretagna e segnalato in europa a partire dal mis14-13, sembra essere presente nella penisola solo dal tardo pleistocene medio (età a mammiferi aureliano: uf di torre in pietra). infatti, le segnalazioni relative al galeriano inferiore e medio sembrano quanto mai infondate, mentre quelle relative al galeriano superiore risultano al momento dubbie o poco attendibili. abstract: l. pandolfi, the skull of stephanorhinus hemitoechus (falconer, 1859) from fosso malafede (vitinia, rome) with notes on the first occurrence of the species in italy. in this work a well-preserved skull of rhinoceros is described. it has been discovered in the upper middle pleistocene fluvial deposits outcropping at fosso malafede (vitinia, rome, central italy) and it is preserved in the museum of paleontology in sapienza, university of rome. comparative analysis of the morphological characters allow to ascribed the skull to stephanorhinus hemitoechus. the specimen shows a well-developed occipital crest, toothrows shifted forward and an extended nasal groove. the degree of wear of the second and third upper molars suggests an about 30-36 year-old individual. s. hemitoechus has been named for the first time by falconer in 1859 from several remains discovered in great britain. this species is present at about 0.500-0.450 million years in continental europe and it is one of the components of the italian late middle and late pleistocene assemblages (aurelian mammal age). the early middle pleistocene remains from slivia, torrente stirone and ponte galeria which are ascribed here to s. hundsheimensis, had been previously assigned to s. hemitoechus. to the latter can be ascribed a mandible discovered in the tiber river terraces at monte verde, referred to the fontana ranuccio faunal unit. however, the chronological correlation of the site is very doubtful. parole chiave: stephanorhinus hemitoechus, tardo pleistocene medio, vitinia, italia centrale. keywords: stephanorhinus hemitoechus, late middle pleistocene, vitinia, central italy. 1. introduzione i rinoceronti rappresentano un elemento abbastanza comune nelle faune pleistoceniche europee, ciò nonostante, la sistematica di questi pachidermi è ancora fonte di dibattito e discussioni. inizialmente tutti i resti di rinoceronte non ascrivibili al genere coelodonta bronn, 1831 furono riferiti al genere rhinoceros l. e successivamente al genere dicerorhinus gloger, 1841. in particolare guérin (1980) ascrisse tali rinoceronti pleistocenici al genere dicerorhinus e attribuì le specie d. jeanvireti guérin, 1972, d. etruscus (falconer, 1868), d. hemitoechus (falconer, 1859) e d. kirchbergensis (jäger, 1839) (= d. mercki [kaup, 1841] in guérin, 1980) al nuovo sottogenere brandtorhinus; successivamente elevato a rango di genere (guérin, 1989). in accordo con groves (1983), i rinoceronti pleistocenici europei mostrano, comunque, poche similarità con il genere dicerorhinus. infatti, fra gli altri caratteri, la perdita e non funzionalità degli incisivi e il setto nasale parzialmente ossificato li distinguono dal suddetto genere attuale. la nomenclatura utilizzata in questo lavoro si basa su quella proposta da fortelius et al. (1993) ed i rinoceronti pleistocenici europei, tranne le specie dei generi coelodonta e elasmotherium fischer, 1808, sono riferiti al genere stephanorhinus kretzoi 1942 così come utilizzato precedentemente da diversi autori (inter alios heissing 1973, 1981, 1989; cerdeño 1993, 1995, 1998; prothero et al. 1986). il cranio analizzato proviene da depositi fluviali di fosso malafede (vitinia, roma), riferibili alla formazione di vitinia (sezione tipo vitinia, roma), 2. il cranio il cranio rinvenuto a fosso malafede (v. 2832) (fig. 1, 2; tab. 1) si presenta danneggiato nei nasali ed in parte nei palatali. a causa della presenza di superfici di l. pandolfi 172 fig. 1 il cranio di s. hemitoechus di fosso malafede (v. 2832): a) norma dorsale, b) norma laterale destra, c) norma laterale sinistra. la barra è di circa 10 cm. the skull of s. hemitoechus from fosso malafede (v. 2832): a) dorsal view, b) right lateral view, c) left lateral view. the bar is of about 10 cm. fig. 2 il cranio di s. hemitoechus di fosso malafede (v. 2832): a) norma occipitale, b) norma basale nucale. the skull of s. hemitoechus from fosso malafede (v. 2832): a) occipital view, b) basal nuchal view. tab. 1 dimensioni comparative del cranio di fosso malafede (v. 2832) e di s. kirchbergensis, s. hemitoechus (dati da guérin, 1980) e s. hundsheimensis di isernia la pineta (dati da lacombat, 2005). dtin = larghezza presa alla fine dell’incisura nasale; dtpo = larghezza presa a livello della costrizione post-orbitale; dto = diametro trasversale della cresta occipitale; dtm = diametro trasversale al livello delle apofisi mastoidee; dtc = diametro massimo trasversale dei condili occipitali; dtf = diametro trasversale del foramen magnum; hf = altezza del foramen magnum. comparative dimensions of the skull from fosso malafede (v. 2832) and of s. kirchbergensis, s. hemitoechus (data from guérin, 1980) and s. hundsheimensis from isernia la pineta (data from lacombat, 2005). dtin = breadth at the end of the nasal groove; dtpo = breadth at level of the post-orbital constriction; dto = breadth of the occipital crest; dtm = breadth at level of the mastoids; dtc = maximal breadth of the occipital condyles; dtf = breadth of the foramen magnum; hf = height of the foramen magnum. il cranio di stephanorhinus hemitoechus … 173 deformazione e di interventi di restauro, alcuni punti utili per ricavare dati morfometrici non possono essere presi in considerazione. in particolare, è stata ricostruita completamente l’arcata zigomatica destra, parte dei lacrimali, il rhinion, parte della base di attacco del corno nasale, il setto nasale, la parte prossimale dei mascellari e gli intermascellari. inoltre mancano quasi tutti i denti ad eccezione del secondo e terzo molare superiore sinistri, molto usurati. 2.1 norma dorsale appare ben evidente la ricostruzione di parte dell’area rostrale, ma, nonostante questo intervento e l’utilizzo di una tinta unita per l’intero cranio dopo il restauro, è ancora visibile una parte della base di attacco del corno nasale. la base di attacco del corno frontale è relativamente ampia e rugosa mentre le creste parietali e frontali non sono distinguibili (fig. 1a). la cavità orbitale sinistra, non ricostruita, è relativamente ampia e di aspetto ellittico, più larga posteriormente. in questa norma, la cresta occipitale presenta un profilo posteriore rettilineo. 2.2 norma laterale l’angolo fra il profilo parietale e quello fronto-nasale è molto accentuato (fig. 1b, c). il setto nasale non è ossificato posteriormente e questo carattere, fra gli altri, permette di distinguerlo dal genere coelodonta. la cresta occipitale si presenta molto sviluppata e si proietta all’indietro oltre i condili. il profilo è leggermente convesso fra i parietali e la cresta occipitale; la base di attacco del corno frontale è appena visibile. gli occipitali presentano un profilo verticale ed i condili occipitali hanno l’apice rivolto verso il basso. l’opisthion è ben evidente al di sopra del foramen magnum. sul lato destro del cranio la regione otica presenta un’apofisi post-glenoidea ben conservata ed un’apofisi paraoccipitale danneggiata nella parte distale, mentre non c’è evidenza dell’apofisi post-timpanica. l’apofisi post-glenoidea è verticale al cranio con profilo anteriore concavo ed è ben separata e distanziata alla base dall’apofisi paraoccipitale. la parte anteriore della cavità orbitale è sita sopra m3/, mentre l’incisura nasale ha il margine posteriore all’altezza di m1/. l’orbita è alta e l’arcata zigomatica sinistra è relativamente massiccia, inclinata e con profilo superiore regolarmente concavo nella parte prossimale. 2.3 norma nucale la faccia occipitale mostra il classico aspetto trapezoidale (fig. 2a). la cresta occipitale ha andamento leggermente convesso e gli occipitali hanno il diametro massimo in corrispondenza delle apofisi mastoidee. il foramen magnum ha forma quasi circolare ed i condili sono ben sviluppati. 2.4 norma basale i condili occipitali sono ben visibili e relativamente distanziati fra loro. in questa visione la cresta occipitale appare relativamente sporgente verso l’indietro. nessun altro carattere è ben distinguibile. l’area palatale è relativamente danneggiata e sul mascellare sinistro sono presenti un m3/ ed un m2/ il cui stadio di usura è particolarmente avanzato (fig. 3a; tab. 2). sul secondo molare è appena visibile la postfossetta, mentre la prefossetta è particolarmente ridotta; il terzo molare ha aspet fig. 3 comparazione fra gli stadi di usura del secondo e terzo molare superiori del cranio di fosso malafede (v. 2832) (a) la barra è di circa 2 cm) e di diceros bicornis (b) range di età stimato di circa 37±4 anni) (ridisegnato da hitchins, 1978) e ceratotherium simum (c) range di età compreso fra 30-38 anni; d) range di età compreso fra 35-40 anni) (ridisegnato da hillman-smith et al., 1986). comparison between the degrees of wear of the second and third upper molars in the skull from fosso malafede (v. 2832) (a) the bar is of about 2 cm) and in diceros bicornis (b) relative age of about 37±4 years) (redrawn from hitchins, 1978) and ceratotherium simum (c) wear class age between 30-48; d) wear class age between 35-40) (redrawn from hillman-smith et al., 1986). l. pandolfi 174 to triangolare e la mediofossetta appare chiusa. inoltre, nel secondo molare non sono più visibili le pieghe vestibolari, né eventuali cingula. lo smalto, a causa dell’usura, è quasi del tutto assente o è ridotto a sottili e piccole placchette sui lati mesiale e distale del secondo molare. 3. comparazione e stima dell’età alla morte il cranio rinvenuto a fosso malafede presenta caratteri morfologici riscontrabili nel genere stephanorhinus e mostra delle affinità con i crani della specie s. hemitoechus. in particolare: ٠ la morfologia dell’occipitale; in s. hemitoechus, infatti, la cresta occipitale si presenta molto sviluppata verso l’indietro tanto da sporgere ben oltre i condili, la squama occipitale è sub-verticale ed i condili occipitali sono rivolti verso il basso (falconer, 1868; azzaroli, 1962; guérin, 1980). questi caratteri, come sopra esposto, sono tutti presenti nel cranio di fosso malafede. in s. kirchbergensis, invece, i condili occipitali tendono a sporgere verso l’indietro più che la cresta occipitale, molto massiccia (azzaroli, 1962; billia, 2006). in s. hundsheimensis (toula, 1902) la cresta occipitale è leggermente sporgente verso l’indietro con bordo posteriore concavo al centro e la faccia occipitale, inferiormente, è leggermente obliqua verso l’indietro e il basso (lacombat, 2005); ٠ l’incisura nasale arretrata e la serie dentaria in posizione avanzata (azzaroli, 1962; guérin, 1980); nel cranio esaminato, come già visto, la parte anteriore della cavità orbitale è sita sopra m3/, mentre la parte posteriore delle cavità nasali si trova in corrispondenza della porzione distale di m1/; ٠ morfologia della regione otica; come ben illustrato da loose (1975) la regione otica dei rinoceronti fossili europei mostra alcune differenze, in parte riprese anche da guérin (1980). in s. hemitoechus, come nel cranio in studio, l’apofisi post-timpanica non è ben evidente e l’apofisi post-glenoidea e quella paraoccipitale sono più distanziate che nelle altre specie dello stesso genere. ٠ arcata zigomatica e posizione dell’orbita relativamente più alta se paragonato con i crani di s. kirchbergensis; questo carattere, tipico della specie s. hemitoechus, è ben descritto e illustrato da azzaroli (1962), loose (1975) e guérin (1980). in aggiunta a tali caratteristiche morfologiche, i valori morfometrici ricavabili dal cranio in studio si identificano molto ai corrispettivi valori medi dati da guérin (1980) per s. hemitoechus (tab. 1). i valori del diametro trasversale della cresta occipitale e del foramen magnum permettono di distinguere l’esemplare in studio da quelli ascritti a s. hundsheimensis del sito di isernia la pineta, mentre meno netta sembra la distinzione con quelli ascrivibili a s. kirchbergensis. le dimensioni del terzo molare superiore risultano maggiori che in s. hundsheimensis e rientrano nel campo di variazione di s. hemitoechus e s. kirchbergensis. il molare in questione si distingue comunque da quest’ultima specie per una minore ampiezza del lato mesiale in rapporto agli altri valori (tab. 2). infine, lo stadio di usura del secondo e del terzo molare superiore, comparata con i corrispondenti stadi di usura dei denti dei rinoceronti attuali riportati da hitchins (1978) e hillman-smith et al. (1986), in particolare per quelli africani, diceros bicornis l. e ceratotherium simum (burchell, 1817), può essere utile per stimare l’età di morte dell’animale. nel cranio in studio, in particolare, il secondo molare ha un profilo vestibolare quasi rettilineo e le fossette sono isolate e molto ridotte così come nel terzo molare. in diceros bicornis, fra i 30 ed i 36 anni di età, il secondo molare presenta le fossette isolate e molto ridotte, mentre il terzo molare ha uno stadio di usura molto avanzato. in aggiunta, nel secondo molare il profilo dell’ectolofo appare quasi rettilineo, il parastilo è assente ed, in generale, la lunghezza vestibolare tende a ridursi (hitchins, 1978) (fig. 3b). in ceratotherium simum, fra i 30 ed i 38 anni di età, si ha la quasi completa usura del secondo molare con le relative fossette che tendono a scomparire ed un’usura molto avanzata del terzo molare (hillmansmith et al., 1986) (fig. 3c, d). infine, l’età massima raggiunta dal rinoceronte nero (diceros bicornis) in natura è tab. 2 dimensione comparate del terzo molare superiore del cranio di fosso malafede (v. 2832) e di s. kirchbergensis, s. hemitoechus e s. hundsheimensis (dati da fortelius et al., 1993). bl = lunghezza buccale; ll = lunghezza linguale; mb = ampiezza mesiale. comparative dimensions of the third upper molar of the skull from fosso malafede (v. 2832) and of s. kirchbergensis, s. hemitoechus and s. hundsheimensis (data from fortelius et al., 1993). bl = buccal length; ll = lingual length; mb = mesial breadth. il cranio di stephanorhinus hemitoechus … 175 compresa fra i 30 ed i 35 anni, con piccole eccezioni che superano i 35 anni, mentre il rinoceronte bianco (ceratotherium simum) raggiunge solo in cattività i 40 anni (hillman-smith et al., 1986; nowak, 1999; brooks, 2002). da quanto sopra esposto si può attribuire al cranio di fosso malafede, con le dovute precauzioni, un’età compresa fra i 30 ed i 36 anni e desumere che il rinoceronte a cui apparteneva doveva essere un individuo senile, probabilmente deceduto a causa dell’età molto avanzata. 4. discussione e conclusioni rhinoceros hemitoechus fu utilizzato per la prima volta da falconer per identificare alcuni resti di rinoceronte rinvenuti in gran bretagna e solitamente il 1868 viene indicato come l’anno di pubblicazione. una nota nel manoscritto del 1868 afferma però che “the important essay on rhin. hemitoechus was written in 1859, but is now for the first time published” (falconer, 1868, pag. 309). dawkins (1867), tuttavia, riporta il nome della specie di falconer nella sinonimia di rhinoceros leptorhinus owen, 1846 affermando che r. hemitoechus è una specie segnalata da falconer (1860) nelle cave di gower (glamorganshire, galles) e che deve la propria esistenza alla traduzione della definizione di owen “à narines demi-cloisonnées” in un nome specifico in greco (dawkins, 1867). in precedenza gaudin (1859), però, affermava che falconer aveva riconosciuto una nuova specie, r. hemitoechus, nelle cave del glamorganshire e pertanto, in accordo con quanto riportato da van der made (2010), il 1859 viene preso come anno di pubblicazione della specie. alcuni autori hanno delineato un trend evolutivo per s. hemitoechus nel corso del tempo, basandosi sulle variazioni nella morfologia e morfometria dei crani e dei denti e delle variazioni di taglia e/o robustezza degli elementi post-craniali (azzaroli, 1962; guérin, 1980; fortelius et al., 1993; lacombat, 2005). in particolare, azzaroli (1962) istituì due sottospecie, una con caratteri meno evoluti per il pleistocene medio (d. hemitoechus falconeri), basata sui crani di bucine, mosbach e clacton ed una più evoluta per il pleistocene superiore (d. hemitoechus aretinus), basata sui crani di botro maspino, ilford ed altri. guérin (1980) ammette in realtà come nome valido per le forme del pleistocene medio d. hemitoechus hemitoechus, indicando minchin hole (cave di glamorganshire, su cui falconer istituì proprio la specie) come località tipo della specie nominale. secondo sutcliffe & bowen (1973) e sutcliffe (1981), però, i sedimenti di minchin hole, sono riferibili all’interglaciale eemiano, per cui la sottospecie nominale “hemitoechus” andrebbe attribuita alle forme del pleistocene superiore, mentre la sottospecie “falconeri” a quelle del pleistocene medio. inoltre, alcuni dei siti in cui azzaroli (1962) segnalava la presenza della forma più evoluta della specie (botro maspino, ponte alla nave) sono stati successivamente riferiti al tardo pleistocene medio o pleistocene superiore (uf di vitinia sensu gliozzi et al., 1997) (fortelius et al., 1993), per cui, il passaggio dalle forme indicate come “falconeri” a quelle indicate come “hemitoechus” potrebbe essere avvenuto prima dell’inizio del pleistocene superiore, presumibilmente intorno al mis7. d’altronde, anche lacombat (2005), sulla base dei resti post-craniali, riporta durante questo periodo un passaggio da forme di taglia più contenuta a forme di taglia decisamente più grande e robusta ed inoltre crani riferibili alla sottospecie s. h. hemitoechus vengono segnalati nei depositi lacustri del sito di neumarck-nord, correlabile con il mis7 (van der made, 2010). il cranio in esame mostra caratteristiche comparabili con i crani di minchin hole e ponte alla nave, come l’angolo fra il profilo parietale e quello fronto-nasale più accentuato ed un profilo più convesso fra i parietali e la cresta occipitale rispetto ai crani di clacton e bucine. in funzione di quanto detto quindi, il cranio di fosso malafede è ascrivibile alla sottospecie s. h. hemitoechus, in accordo anche con l’età del deposito in cui è stato rinvenuto. resti di s. hemitoechus sono segnalati in buona parte dell’europa centro-meridionale e parte della gran bretagna nonché in nord africa e medio oriente. la presenza di questa specie in asia sembra al momento molto dubbia; guérin (1980) riteneva, comunque, che i resti di rinoceronte di binagad (azerbaidjan), descritti da dzhafarov nel 1955, potessero essere riferiti a dicerorhinus hemitoechus. nell’europa continentale le segnalazioni più antiche riferibili a questa specie sono datate intorno alla seconda metà del pleistocene medio (ad esempio in siti come caune de l’arago; guérin, 1980; lacombat, 2005). in italia la prima presenza di questo rinoceronte veniva segnalata nella breccia ossifera di slivia, riferibile alla uf omonima (compresa fra i 900.000 e gli 800.000 anni bp) (ambrosetti et al., 1979; bon et al., 1992; gliozzi et al., 1997; palombo, 2004; palombo & mussi, 2006). in realtà i reperti presenti nella suddetta breccia meriterebbero un’osservazione più attenta in quanto la morfologia dei denti riportati in bon et al. (1992: fig. 3, pag. 39) si avvicina, a parere dello scrivente, più a quella di s. hundsheimensis che a s. hemitoechus (petronio & pandolfi, 2008). inoltre, tali resti venivano riferiti da ambrosetti et al. (1979) a forme intermedie fra s. etruscus e s. hemitoechus, paragonabili alle popolazioni di voigstedt e süssenborn, successivamente ascritte proprio a s. hundsheimensis. a questa specie sono riferibili anche i resti di rinoceronte provenienti dai depositi pleistocenici del torrente stirone (800-700 mila anni) ed assegnati da cigala fulgosi (1976) a d. hemitoechus. il cranio proveniente da questo sito infatti è comparabile con quello di altri esemplari di s. hundsheimensis e presenta, rispetto a s. etruscus, un angolo fra parietali e frontali più aperto con nasali e frontali più allungati, incisura nasale più lunga e orbite più strette, mentre rispetto a s. hemitoechus presenta una faccia occipitale inferiormente più obliqua verso l’indietro e il basso, con la sommità meno estesa verso l’indietro, un profilo della cresta occipitale concavo e, infine, un allargamento posteriore delle arcate zigomatiche meno marcato. una mandibola, completa di serie dentaria, ed ascritta a s. hemitoechus, viene segnalata nei livelli a sabbie e conglomerati del sito di cava di breccia di ponte galeria (petronio, 1988), correlabili con un intervallo cronologico compreso fra i 750.000 ed i 650.000 anni (petronio & sardella, 1999). la mandibola in questione ed i denti ad essa connessi, presentano però caratteri morfologici e morfometrici comparabili con s. l. pandolfi 176 hundsheimensis. in particolare, il p/2 presenta la sola valle posteriore ed ha dimensioni relativamente grandi, a differenza della specie s. hemitoechus che presenta, nel medesimo dente, anche una valle anteriore e dimensioni più contenute (guérin, 1980; lacombat, 2005). infine, altro elemento morfologico importante, le valli posteriori di m/2 e di m/3 della mandibola di ponte galeria si presentano ad u, mentre in s. hemitoechus la morfologia della valli è quasi esclusivamente a forma di v (guérin, 1980; lacombat, 2005). si può aggiungere che non esistono al momento segnalazioni relative a s. hemitoechus in siti riferibili alla uf di isernia (compresa fra i 650.000 ed i 550.000 anni bp), considerando anche che la segnalazione nel sito di visogliano (bartolomei et al., 1977; fortelius et al., 1993) è stata poi riferita a s. hundsheimensis da abbazzi et al. (2000) e sardella et al. (2006). infine, un frammento di mandibola con m/1 ed m/2 proveniente dai depositi fluviali di monte verde (roma) può essere attribuita a s. hemitoechus per la presenza, nei molari, di valli linguali a forma di v, di cingula linguali e per la differenza quasi nulla in altezza fra le basi delle suddette valli (cfr. lacombat, 2006). per la presenza di bos primigenius ed ursus deningeri, i depositi in questione vengono correlati con la uf di fontana ranuccio (sensu gliozzi et al., 1997; di stefano et al., 1998). in realtà i reperti sono stati raccolti all’inizio del secolo scorso da terrazzi del tevere; di questi rinvenimenti tuttavia non si conosce la posizione stratigrafia e non si è certi nemmeno della precisa provenienza. resti attribuibili a s. hemitoechus sono segnalati a partire dalla uf di torre in pietra (sensu gliozzi et al., 1997). in particolare, questa specie è presente nei livelli inferiori di torre in pietra, a castel di guido, cretone e malagrotta (capasso barbato & petronio, 1981; caloi & palombo, 1978, 1979; di stefano et al., 1998; di canzio et al., 2003). s. hemitoechus risulta ben rappresentato nelle associazioni faunistiche riferite anche alla uf di vitinia (sensu gliozzi et al., 1997) come quelle rinvenute nei depositi di monte sacro, prati fiscali e tor di quinto (di stefano et al., 1998). recentemente, palombo et al. (2003), sulla base di nuove interpretazioni stratigrafiche e datazioni radiometriche di alcuni siti dell’area urbana di roma, suggeriscono di destituire la uf di vitinia e di riferire tutti i complessi faunistici del tardo pleistocene medio del lazio alla uf di torre in pietra. questo perché i bioeventi che caratterizzano la uf di vitinia così come formalizzata da gliozzi et al. (1997) sarebbero predatati e la uf di torre in pietra, nella sua nuova definizione, sarebbe caratterizzata dalle prime comparse di canis lupus l., ursus spelaeus rosenmüller & heinroth, 1794, megaloceros giganteus blumenbach, 1799, dama dama tiberina di stefano & petronio, 1997 e dalla persistenza di dama clactoniana (falconer, 1868) (palombo et al., 2003). la nuova uf di torre in pietra comprenderebbe così tutte le associazioni faunistiche rinvenute nei depositi riferibili alle formazioni aurelia e vitinia o nelle sequenze deposizionali di quarto ordine pg6 (mis10-8) e pg7 (mis8-6) descritte da milli (1997). di conseguenza, l’intervallo temporale definito dalla uf di torre in pietra risulta dilatato rispetto a quanto riportato da gliozzi et al. (1997). fortunatamente, il cranio in esame proviene da depositi riferibili alla formazione vitinia (mis7), per cui, in questo caso, l’età relativa del reperto rimane invariata, così come rimane invariata l’età dei reperti provenienti dai livelli inferiori del sito di torre in pietra, riferibili alla formazione aurelia. diversa è invece la situazione per siti come cretone, tor di quinto e monte sacro, i cui depositi, al momento, non risultano inquadrabili in una delle due formazioni; i siti in questione sono quindi correlabili con un intervallo temporale che va dal mis10 al mis6. probabilmente, ulteriori analisi morfologiche e morfometriche dei resti di rinoceronte provenienti dai suddetti siti permetterà di riferire gli stessi ad uno degli stadi evolutivi di s. hemitoechus che caratterizzano il pleistocene e quindi correlare i siti in questione con un intervallo temporale più ristretto. in accordo quindi con quanto sopra discusso, la comparsa di s. hemitoechus in italia andrebbe, al momento, a collocarsi con certezza all’inizio dell’età a mammiferi aureliano (uf di torre in pietra) in depositi riferibili alla formazione aurelia (mis10-8). bibliografia abbazzi l., fanfani f., ferretti m.p., rook l., cattani l., masini f., mallegni f., negrino f. & tozzi c. 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(1934) die beziehungen zwischen schädelform und lebensweise bei den rezenten und fossilen nashörnern berichte der naturforschenden gesellschaft zu freiburg, 34, pp. 21-80. ms. ricevuto il 27 ottobre 2010 testo definitivo ricevuto il 31 maggio 2011 ms. received: october 27, 2010 final text received: may 31, 2011 microsoft word 00_indice_lm04.docx il quaternario it issn 039-3356 italian journal of quaternary sciences 24 (1), 2011 41-50 the palaeontological campaigns of alberto malatesta in the mediterranean islands odoardo girotti1, tassos kotsakis2 & carmelo petronio1 1 dipartimento di scienze della terra, università di roma sapienza, roma 2 dipartimento di scienze geologiche e centro di ecologia evolutiva, università di roma tre, roma corresponding author: t. kotsakis <kotsakis@uniroma3.it> abstract: girotti o., kotsakis t. & petronio c., palaeontological campaigns of alberto malatesta in the mediterranean islands. a short account of the palaeontological campaigns organized and led by alberto malatesta in the mediterranean islands, in search of quaternary endemic vertebrates, is presented in this paper. the activity of malatesta in such a field can be grouped in four periods. the first period (1964-1970) deals with his researches in sardinia (dragonara cave, nettuno cave, capo figari); the second one (19701972) includes the field campaigns in crete (simonelli cave and katharo plateau); the third period (1972-1978) regards the researches in sicily (capo tindari cave); during the last period (1979-1984) the scientific interests of malatesta returned back to sardinia (is oreris quarry, alghero neighbours). for each locality, a brief exposition of the principal results is presented together with a summary of the research and revision papers that malatesta and his co-workers wrote on the material collected during the field seasons. riassunto: girotti o., kotsakis t. & petronio c., campagne paleontologiche di alberto malatesta nelle isole del mediterraneo. in questo lavoro viene presentata una breve sintesi delle campagne paleontologiche nelle isole del mediterraneo organizzate e dirette da alberto malatesta, in cerca di giacimenti di vertebrati endemici del quaternario. l’attività di malatesta in questo campo è divisa in quattro periodi. durante il primo periodo (1964-1970) i suoi interessi sono concentrati sulle faune insulari della sardegna (grotta di dragonara, grotta di nettuno, capo figari). il secondo periodo (1970-1972) comprende le tre spedizioni all’isola di creta (grotta simonelli, altipiano di katharo). il terzo periodo (1972-1978) vede gli interessi di malatesta spostarsi verso la sicilia (grotta di capo tindari). infine durante il quarto periodo (1979-1984) si ritorna a ricerche in sardegna (cava di is oreris, dintorni di alghero). per ogni località esplorata vengono date sommarie notizie circa i risultati ottenuti e vengono riportati i lavori che illustrano queste faune, sia quelli di malatesta e dei suoi collaboratori, sia quelli di revisione o ampliamento di studi, fatti su materiale raccolto durante questi scavi. key words: biography, palaeontological campaigns. parole-chiave: biografia, campagne di scavi paleontologici. 1. introduction the quarter of the xx century that went from the beginning of the sixties till the half of the eighties was particularly fruitful for the palaeontological researches of the then-institute of geology and palaeontology of the university of rome (included in the last years of that period in the department of earth sciences). the most important character of that period was not only a considerable increase in the number of publications (during the years that followed, the publications were even more numerous), but especially a large increase of the collected fossil material. this was true for all fields of palaeontology (microfossils, invertebrates and vertebrates), but the sector that presented, at least macroscopically, the most spectacular results, was the field of vertebrates. this situation is clearly evidenced by the large number of skeletons of fossil vertebrates that were mounted in the museum of palaeontology during those years. the start of the campaigns for the collection of vertebrate fossils was given by angiola maria maccagno in the fifties, but further development was due to a combination of factors including the presence of bruno accordi as the director of the institute (and of the museum of palaeontology) from 1959 and of alberto malatesta as the professor of palaeontology since 1963. the two men differed in many things but certainly shared the interest on the island vertebrate fossils. for accordi the years at the university of catania, the study of the endemic hippo of sicily (hippopotamus pentlandi von meyer), and the discovery of the cave of spinagallo (accordi, 1955; accordi & colacicchi, 1962) led to an increasing interest on the problems of insular gigantism and dwarfism. for malatesta similar opportunities were the geological surveys for several geological maps of both sicily and sardinia (during his employment at the italian geological survey); in fact they gave him the possibility to identify fossil deposits of endemic island faunas and to direct its scientific interest to this field. so, what characterized the activity of a. malatesta during this period were the palaeontological campaigns in the mediterranean islands to collect endemic quaternary vertebrates and these activities will be discussed in more detail. the scientific activities of alberto malatesta were not limited to the palaeontological campaigns we are going to expose. many of his work was devoted to the o. girotti, t. kotsakis & c. petronio 42 study of the stratigraphy of various localities of the italian peninsula and to the systematic study of vertebrates and especially molluscs collected in several sites. malatesta, assisted by odoardo girotti and giuseppe sirna, started, since 1964, to collect marine molluscs from the pliocene clayey deposits of umbria, along the rivers chiani, paglia and tiber. the collection went on for short intervals during the following years. the systematic results were published in 1974 in a huge volume (malatesta, 1974). malatesta worked on the stratigraphy and on the fossil faunas of grotta della madonna at praia a mare (calabria), torre in pietra (latium), and of several other areas of latium. during these studies he collaborated with lucia caloi, luigi cardini, piero cassoli, vittorio conato, daniela esu, elsa gliozzi, maria rita palombo, and, especially in the last years of his activities, with francesco zarlenga (malatesta, 1978a; conato et al., 1980; malatesta & zarlenga, 1986, 1988). in september-october 1980 malatesta and zarlenga led a campaign to collect paleocene molluscs in the basin of rio massintonto (maputo), with the financial support of the compagnia bonifica. the rich mollusc fauna, containing a large number of new taxa, was described by malatesta & gliozzi (1983). 2. sardinia: dragonara cave, nettuno cave, capo figari (1964-1970) returning to our main topic, the island campaigns, it should be noted that malatesta had already collected fossil material from the dragonara cave (porto conte, sardinia) and some other localities of the area during the first half of the fifties (malatesta & settepassi, 1954), and in 1962 he published the first work on the endemic canid of sardinia, without giving a precise indication of the fossiliferous locality, since the site was object of a preliminary collection only, and new campaigns were planned (malatesta, 1962). the first of the campaigns at dragonara was organized in the summer of 1964. the team was composed by pierluigi ambrosetti, odoardo girotti, valerio palmerini, giuseppe sirna, and a. malatesta as the leader (fig. 1). the dragonara cave opens to about one meter a.s.l. and is accessible only by sea. the investigating team was camped about 200 m from the cave and reached the site using a boat or, sometimes, swimming. the three weeks of work were particularly successful and notable quantities of material were collected. however, the cave was still full of fossils, and malatesta planned two additional campaigns. the second campaign (lasted two weeks) was held in the spring of 1969 with the participation of carmelo petronio, valentino pettinella and giuseppe sirna (figs. 2, 3) and increased the fossil material already collected. the third one was organized in the spring of 1970 and lasted three weeks. that time, under the leadership of a. malatesta, c. petronio, v. pettinella, claudio romei and others were the members of the team. the material collected after the first two campaigns was considered sufficient by malatesta (1970) to complete a monograph on cynotherium sardoum, the sardinian endemic canid, on which, as we have seen, he devoted a preliminary note. on the contrary, to describe the endemic deer praemegaceros cazioti (depéret), the specimens collected during the third expedition were also fig. 1 summer 1964: group photo at the end of the campaign at the dragonara cave (sardinia). from left: v. palmerini, p. ambrosetti, a. malatesta, o. girotti, and g. sirna. estate 1964: foto di gruppo al termine della campagna di scavo alla grotta di dragonara (sardegna). da sinistra: v. palmerini, p. ambrosetti, a. malatesta, o. girotti e g. sirna. the palaeontological campaigns of alberto malatesta in the mediterranean islands 43 fig. 2 spring 1969: a moment of rest during the excavation at the dragonara cave (sardinia). from left: a. malatesta, c. petronio, g. sirna., and v. pettinella. primavera 1969: un momento di riposo durante lo scavo: della grotta di dragonara (sardegna). da sinistra: a. malatesta, c. petronio, g. sirna., e v. pettinella. fig. 3 spring 1969: c. petronio (from back) and a. malatesta look at the excavation within the dragonara cave (sardinia). c. petronio (di spalle) e a. malatesta osservano lo scavo all’interno della grotta di dragonara (sardegna). considered (caloi & malatesta, 1974). the fossil remains of the deer were further studied under several morphological-functional aspects from caloi & palombo (1991, 1995) and palombo (2005) and the data obtained from this “population” were used for studies and for models involving adaptive changes in the morphology of the island endemic deer. the “hunterschreger bands” of the canid of dragonara were also object of a study (novelli & palombo, 2007). besides the two large mammals (the canid and the cervid) a small carnivore, four species of small mammals, many species of birds and some species of amphibians and reptiles were discovered at dragonara. the small mammals have never been studied in an analytical way (there is only a master thesis). a partial study of the teeth of the arvicolid microtus (tyrrhenicola) henseli (major) was published by minieri et al. (1995). for birds malatesta & suriano (1971) provided a list of species, while the fossil herpetofauna was studied by kotsakis (1980a). the remains of a small carnivore, a lutrine, proved to be of particular interest; despite their paucity, they have allowed to establish a new endemic sardinian species (malatesta, 1978b), some years later transferred (willemsen & malatesta, 1986) to an endemic genus, algarolutra majori (malatesta). gliozzi (1985) studied some postcranial remains of this species. the dragonara assemblage is at present considered representative of the late pleistocene “classical” sardinian fauna: in her biochronological chart of fossil mammal assemblages of sardinia, palombo (2006) has proposed the dragonara faunal sub-complex of the microtus (tyrrhenicola) complex, corresponding to the latest middle pleistocene earliest holocene time span. o. girotti, t. kotsakis & c. petronio 44 between the first and the second campaigns of dragonara, in the early months of 1966, malatesta and piero cassoli, invited in sardinia by the tourist office of alghero to visit some caves, had the chance to see an otter skull collected by some speleologists in the cave of nettuno (near capo caccia). malatesta, informed of the presence of the entire skeleton, organized a miniexpedition during the month of september of that year and, accompanied by some local speleologists (p. bradis, g. pala), reached the tunnel patrizi where a complete skeleton of the lutrine laid, partly outcropping on the sand and partly buried in it, at about 4 m a.s.l. (fig. 4). despite the narrowness of the tunnel, it was possible to collect all the bones of the entire skeleton, which remained not studied for a long time. the description of the species was made by malatesta in 1977, when he established the endemic species nesolutra ichnusae malatesta, whose age should be holocene. this lutrine clearly lived in the sea and presumably had similar habits to the recent north pacific sea otter, enhydra lutris (linnaeus). malatesta came to this conclusion observing the penial bone (obviously the skeleton belonged to a male). several years later, willemsen (1992) carried on a review of the plio-quaternary lutrini of europe and established a new endemic genus for the sardinian sea otter, sardolutra ichnusae (malatesta). angelelli (1995) carried out a study of the morphology of the endocranial cast of this species. during the expedition of 1970, after the end of the excavation of dragonara, the collection of fossil material from a breccia of capo figari, was also organized. the site was known for the excavations carried out there by c. i. forsyth major (between the end of the nineteenth century and the beginning of the twentieth century) and by e. g. déhaut who identified a fossil antelope and other mammals. the british palaeontologist did not publish the results of his researches (he just mentioned the presence of a fossil monkey). malatesta, who had previously visited the place and identified a fossiliferous site he believed (probably correctly) to be the site excavated by déhaut, organized the collection of samples form a very hard breccia. he rewarded, at least in part, of his expectations, after the fossils were prepared in the laboratory in rome. also if he failed to recover any fossil remain of the monkey, as he hoped, he instead managed to get some important remains of the antelope. the material studied by gliozzi & malatesta (1980) allowed establishing a new genus for the antelope, nesogoral melonii (déhaut). a second publication described the endocranial morphology of this ruminant (angelelli et al., 1982). compared to the fauna of dragonara, the fauna of capo figari is much older. the generic name of the antelope has been used by palombo (2006) to indicate the older of the two faunal complexes proposed for the plio-pleistocene faunas of sardinia: nesogoral faunal complex consisting of two sub-complexes. the most recent of these is called capo figari / orosei 1 sub-complex, roughly corresponding to the early pleistocene. according to a communication of malatesta to one of the authors of this paper (t.k.), during the sixties malatesta visited also the island of tavolara (north-eastern sardinia) and collected some subfossil remains of birds (?puffinus). no organized campaigns of excavation at tavolara appear to have been organised and, probably, the bird material was collected during a short visit of malatesta alone. 3. crete: simonelli cave and katharo (1970-1972) in the same year of the campaign at dragonara and capo figari, bruno accordi managed to achieve considerable funding from the accademia nazionale dei lincei for excavations focused on the collection of fossil insular endemic vertebrates. he then asked malatesta about the possibility of organizing an excavation at crete, an island whose quaternary endemic mammals were partly known through the papers (late xix early xx centuries) of dorothy bate and vittorio simonelli. about that time (late sixties-early seventies) the data on these mammalian faunas were increased through the work of siegfried kuss and paul sondaar. a. malatesta (fig. 5), fig. 5 september 1970: a. malatesta at iraklion (crete). settembre 1970: a. malatesta ad iraklion (creta). the palaeontological campaigns of alberto malatesta in the mediterranean islands 45 o. girotti and g. sirna embarked on an “exploring expedition” to identify possible fossiliferous sites to excavate. attention was focused on the caves along the cliffs on the northern coast, west of the city of rethymno. after several attempts, the group was able to find a cave that seemed to promise a large amount of fossil remains, just west of rethymno barracks, then to west end of the town. during the winter 1971 contacts were made for a collaboration with prof. yannis melentis of the university of thessaloniki. the expedition set off during september of that year, was led by alberto malatesta and comprised, among the italian members antonello angelucci, giacomo civitelli, o. girotti, t. kotsakis, v. pettinella, a. praturlon, c. romei and g. sirna, and among the greek members y. melentis, d. mountrakis and g. soulios. later on also b. accordi joined the excavations. the intuition of the “exploring expedition” proved to be correct. the cave contained an enormous amount of material of late pleistocene age. the vast majority of the remains belonged to a small deer. the cave, which was named “grotta simonelli” in honor of the italian palaeontologist of the beginning of the xx century who had first described the remains of the little endemic deer, was not easily accessible by land and the transport of the collected material was done with mules. the excavation lasted five weeks. during this period a. malatesta, with o. girotti and, in turn, with another member of the expedition, visited some other fossiliferous sites known from the geological literature. in particular he visited for five days (with girotti and kotsakis) the katharo plateau (in the eastern part of the island) where boekschoten & sondaar (1966) had reported the remains of a dwarf hippopotamus (fig. 6). rather fragmentary fossil remains were scattered over a large surface area of this ancient lacustrine basin. a few days later, while the excavations at “grotta simonelli” continued, malatesta, girotti and kotsakis visited the island of cyprus. thanks to m. mantis of the geological survey of cyprus they visited some “classic” places discovered by miss bate. but apart from the collection of some small samples, this “exploring expedition” was not followed by any larger campaign. preliminary results of the cretan expedition were published by accordi (1972) and melentis (1974). the restoration of the material lasted for a long time. the analytical study of the cervid praemegaceros cretensis (simonelli) was published by malatesta (1980) and was supplemented by several other minor notes on the rest of the fauna, elephants, carnivores (subfossils), birds, reptiles and the study of the endocranial morphology of the endemic deer (angelelli, 1980; caloi, 1980; kotsakis, 1980b; mangilli, 1980; suriano, 1980). again, like the fossils of the dragonara cave, the simonelli cave findings offered the possibility of additional studies on several aspects of the adaptations of the endemic mammals (palombo & petronio, 1989; caloi & palombo, 1996; palombo et al., 2008). the expedition of 1971 had an epilogue in the next year. malatesta led a further expedition in september 1972, with the participation of t. kotsakis, c. petronio and v. pettinella (fig. 7). the expedi o. girotti, t. kotsakis & c. petronio 46 fig. 8 september 1972: katharo plateau. dried streamlet showing lacustrine clayey marls overlain by debris flow. v. pettinella indicates the outcrop with bones. settembre 1972: altipiano di katharo (creta). letto asciutto di un torrente in cui affiorano le marne argillose sovrastate da depositi di debris flow. v. pettinella indica il punto dell’affioramento fossilifero. tion lasted three weeks, two of which were spent on the katharo plateau. during this field work, some remains of the endemic ?middle pleistocene hippo of crete, hippopotamus creutzburgi boekschoten & sondaar, were recovered (figs. 8, 9); they were described ten years later fig. 9 a detail of the outcrop of fig. 8 with fossil hippo remains. un dettaglio dell’affioramento illustrato in fig. 8 con i resti fossili di ippopotamo. by capasso barbato et al. (1982) and reviewed in a morphological-functional perspective by caloi & palombo (1996). two of the authors of these pages recall a typical scene that took place in a good hotel in aghios nikolaos, which we entered soon after our descent from katharo (where we stayed for a fortnight in a tent, obviously free camping). the smell around us should not have been the most pleasant, because we saw the reception employees that we watched with vigilant eyes, with a sense of annoyance and almost hostility. but when they heard our cries to malatesta: “professore! professore!”, their sights changed and one said to the others: a! αρχαιολογοι! and smiled again! the research group of palaeontologists of the roma university, again in collaboration with the university of thessaloniki, carried on other expeditions in crete in later years, (kotsakis et al., 1976), but a. malatesta did not join them. 4. sicily: capo tindari (1972-1978) during the field work in sicily’s northern coast around capo tindari, malatesta (1958) reported for the first time the presence of a cave filled with abundant fossils, known locally as the “grotta della fata donnavilla”. the cavity opens along the cliffs of capo tindari at a height of 76 m a.s.l. the access was very difficult and the palaeontological campaigns of alberto malatesta in the mediterranean islands 47 the cave could be reached only by walking on a small edge protruding from the rock that was even broken partially in some points. the material collected during the fifties was increased in two expeditions conducted in 1973 and 1974 respectively. c. petronio, v. pettinella and c. romei took part to the first, while in the second one malatesta was accompanied only by c. romei. during this last field excursion (rather than expedition) various places in the provinces of enna and caltanissetta were visited in search of sites with lower paleolithic industry. however, these searches were fruitless. the last campaign to capo tindari dates back to 1978. in addition to malatesta, who led the group, francesco angelelli, l. caloi, t. kotsakis, m.r. palombo, c. petronio, v. pettinella and c. romei were present. during this final expedition, which dedicated to capo tindari a week of work, the collection of deer remains was increased and some rare remains of hippo were found (fig. 10). in the unconsolidated superficial fraction of the sediment some small mammal remains were collected. just during the last day of the excavation, a serious accident happened, with the risk that some staff member fell down the cliff (that was 76 m height). fortunately, the intervention of v. pettinella and c. romei prevented the successful scientific trip to end in a tragedy. the material collected belonged to two deers, the endemic sicilian hippopotamus hippopotamus pentlandi, and a small bear, ursus sp. a preliminary communication on the fossils collected fig. 10 settembre 1978: l. caloi (on the left) and a. malatesta look at a fossil bone fragment collected during the excavation of the tindari cave (sicily). on the right, m.r. palombo is moving out of the picture settembre 1978: l caloi (a sinistra) e a. malatesta osservano un frammento di osso fossile raccolto durante lo scavo della grotta di tindari (sicilia). a destra, m.r. palombo sta uscendo dalla foto. in the fifties was made by caloi (1973) who described some remains of deer and hippo. a detailed description of one species of deer was published by gliozzi & malatesta (1982) who attributed the majority of the cervid remains collected in cave of capo tindari to praemegaceros (notomegaceros) carburangelensis (de gregorio) a form of endemic sicilian megacerine, for which a new endemic subgenus was proposed. in an appendix to this work caloi & palombo (1982) illustrated the few remains of endemic hippopotamus. the remains of the second deer, an endemic sicilian subspecies of the red deer, cervus elaphus siciliae pohlig, of latest middle pleistocene to late pleistocene age, were described together with all the remains belonging to this form by gliozzi et al. (1993). the first species of deer is now ascribed to dama carburangelensis (de gregorio) by abbazzi et al. (2001). 5. sardinia again (1979-1984) in the second half of may 1979, malatesta organized an “exploring expedition” with t. kotsakis in sardinia, which lasted two weeks. a special feature of this expedition was the fact that they moved always by train and on foot. the first result of the expedition was the identification of a rich accumulation of small vertebrate bones in the alabaster quarry, an abandoned part of the mine of santa lucia in is oreris (iglesiente, swsardinia). the site was already known in the palaeontological literature for the discovery of a skull of the endemic sardinian monkey, macaca majori azzaroli, by comaschi caria (1970). the second fossiliferous locality object of this visit was a cavity discovered by malatesta in the early ’50s to the south of alghero between punta padrebellu and omo morto. malatesta remembered a footpath leading to the south of the city of alghero to the fossiliferous locality. instead of the path we come across the wide alghero-bosa asphalt road, with cars darting at high speed. the fossiliferous cavity was no more, but some blocks lying along the cliff gave few remains of small mammals and especially a small group of fossil bats of late pleistocene age, illustrated by kotsakis in 1987. in november 1983, malatesta led a second expedition at is oreris with elsa gliozzi and m. r. palombo; it lasted ten days and a certain amount of remnants of small vertebrates were collected from the very hard breccia. a few months later, in april 1984 malatesta led what it proved to be his last paleontological campaign in the island. the team was composed by l. caloi, d. esu, e. gliozzi, t. kotsakis and m.r. palombo. the expedition lasted about two weeks and was almost the farewell to the sardinian campaigns of malatesta. during this campaign they been visited a lot of places he had surveyed in the past. in the alabaster quarry at is oreris, further samples were collected to enrich the collection of small vertebrates under study. a few samples were also collected at capo figari (figs. 11, 12). south of alghero, while in the locality calabona the remains of many freshwater molluscs were collected. the results of both these expeditions were published by gliozzi et al. (1984) and minieri et al. (1995) as for the small mammals of the alabaster quarry and by esu (1987) as to the calabona molluscs. the fauna o. girotti, t. kotsakis & c. petronio 48 fig. 11 april 1984: sampling of the fossiliferous breccias cropping out at capo figari (sardinia). from the left: d. esu, t. kotsakis, a. malatesta, and m.r. palombo. aprile 1984: campionamento della breccia ossifera affiorante a capo figari (sardegna). da sinistra: d. esu, t. kotsakis, a. malatesta e m.r. palombo. of is oreris was composed by two insectivores “nesiotites” similis (hensel) and talpa tyrrhenica bate, two rodents, tyrrhenicola henseli major and rhagamys orthodon (hensel) and one lagomorph prolagus sardus (wagner), all members of the “classic” late pleistocene faunal assemblage of late pleistocene. as a matter of fact, palombo (2006) places the fauna of is oreris in the faunal subcomplex of dragonara, although she considered this fauna somewhat older if compared to the fauna of dragonara. malatesta returned again in sardinia to study, in collaboration with willemsen, a third endemic lutrine of the island. however this was not a campaign for field work, but a visit to the museum of nuoro. the results of the study (willemsen & malatesta, 1987) were the establishment of a new taxon, endemic to the generic level, megalenhydris barbaricina willemsen & malatesta. 6. conclusions regardless of field work for geological survey and mapping of the fifties, the number of explorative expeditions and excavation campaigns organized and directed by alberto malatesta in search of quaternary insular vertebrates were fourteen (seven in sardinia, three in sicily, three in crete and one in cyprus). the excavations were certainly not organized with a detail similar to those carried out by prehistory archaeologists and which are now the norm for palaeontological excavations in the caves. they were the typical excavations organized to recover large mammals, with an increasing attention to the collection of small vertebrates. the analysis and publication of data always followed the criteria of detailed descriptions and illustrations of all bones. the great value that malatesta’s publications have today, decades after their appearance, lies on the detailed description, and remains significant, although the systematic, phylogenetic, palaeobiogographic and palaeoecologic conclusions can be partly overcome. malatesta has not formally taught to most of his students how organize the research. but he directed some of them to the scientific paths they have later followed. he pointed to odoardo girotti a field of interest in the study of non-marine molluscs of the tiber basin. this study started the girotti’s research field on the bivalves and gastropods of brackish and continental deposits. girotti, on his turn, transmitted this research topic to daniela esu and their collaboration in this field continues without interruption since more than thirty five years. carmelo petronio, maria rita palombo, lucia caloi and tassos kotsakis and, in the early stages of his career also elsa gliozzi, have been influenced by malatesta in the researches on vertebrate fossils. if we calculate the percentage of the publications that each of these palaeontologists devoted to problems of insular fig. 12 april 1984: group photo at the end of the campaign at is oreris-capo figari (sardinia). from left: l. caloi, a. malatesta, m.r. palombo d. esu, t. kotsakis and e. gliozzi. aprile 1984: foto di gruppo al termine della campagna di scavi a is oreris-capo figari (sardegna). da sinistra: l. caloi, a. malatesta, m.r. palombo d. esu, t. kotsakis e e. gliozzi. the palaeontological campaigns of alberto malatesta in the mediterranean islands 49 vertebrates, emerge that malatesta’s influence has been considerable and constant. this influence was certainly also felt by his other students but we limit to speak here only of those who participated to the palaeontological campaigns to the islands led by him. malatesta’s character was not easy and during the expeditions he always kept a certain hierarchical structure of the staff. this was pretty easy to obtain standing in the institute and the laboratory, but became more difficult in the intimacy of the excavations and in the camps, and this sometimes led to tensions. however, that attitude weakened as the years passed. even different opinions in cultural and political fields were sometimes occasions of heated discussions, but also those were mitigated over time, with a spirit of greater understanding between the group leader and his younger colleagues, until they reached a real human warmth, when his students in 1995, celebrated his eightieth birthday. references abbazzi l., bonfiglio l., marra a.c. & masini f. 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(1987) megalenhydris barbaricina gen. nov. sp. nov., a new otter from sardinia. proc. kon. ned. akad. wetensch., ser. b, 90, pp. 83-92. ms. ricevuto il 22/12/2010 testo definitivo ricevuto il 20/05/2011 ms. received: december 22, 2010 final text received: may 20, 2011 amq34(2) 201-211 lopezgarcia et al def.pdf available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 34 (2), 2021, 201-211 using small mammals to reconstruct the climatic context of the late pleistocene lagar velho rockshelter (leiria, portugal). juan manuel lópez-garcía 1,2, carlos pimenta 3, ana cristina araújo 3,4,5, ana maria costa 3,4,6, montserrat sanz 5,7, joan daura5,7 1 institut català de paleoecologia humana i evolució social (iphes-cerca), campus sescelades urv, tarragona, spain. 2 universitat rovira i virgili, departament d’història i història de l’art, tarragona, spain. 3 laboratório de arqueociências (larc)-dgpc, lisboa, portugal. 4 inbio, and cibio, university of porto, portugal. 5 uniarq-centro de arqueologia da universidade de lisboa, universidade de lisboa, lisboa, portugal. 6 idl, instituto dom luiz, universidade de lisboa, lisboa, portugal. 7 grup de recerca del quaternari, grq-serp, department of history and archaeology, university of barcelona, barcelona, spain. corresponding author: juan manuel lópez-garcía <jmlopez@iphes.cat> abstract: to reconstruct the climatic conditions of the lagar velho rockshelter during the late pleistocene, we applied the bioclimatic model to the rodent assemblages, mainly composed of the vole species arvicola sapidus, microtus arvalis, microtus agrestis, microtus (terricola) lusitanicus and microtus (iberomys) cabrerae and the field mouse apodemus sylvaticus. based on the distribution of these species by layers and percentages, considering different climate-types, and applying a series of functions, it was possible to estimate the mean annual temperature (mat), the mean temperature of the coldest month (mtc), the mean temperature of the warmest month (mtw) and the mean annual precipitation (map). for comparative purposes, the resulting parameters were compared with climate data obtained for the last 30 years from nearby meteorological stations in order to attain averages and observe climatic fluctuations. the climatic parameters were then compared with the köppen-geiger classification in order to contrast our data with the current climate-types. finally, we combined the results with chronological and environmental information to produce a climate framework within marine isotope stage 2 (mis 2). keywords: bioclimatic model, köppen-geiger classification, marine isotope stage 2, heinrich events, last glacial maximum, iberian peninsula. 1. introduction marine isotope stage 2 (mis 2; ca. 29 to 14.9 kyr b.p.) corresponds to the last portion of the most recent glaciation (ishiwa et al., 2019). in the iberian peninsula, the pollen spectra for mis 2 suggest in general an open landscape dominated by semi-arid vegetation (fletcher & sanchez-goñi, 2008). this stage includes the last glacial maximum (lgm, ca. 27-17 kyr b.p.), when the ice sheets reached their greatest volume (hein et al., 2010; ishiwa et al., 2019, among others). it also includes the most recent heinrich events, which produced the ird (ice-rafted debris) layers observed in marine sediment cores from the north atlantic, notably heinrich event 3 (h3; ca. 31-29 kyr b.p.), which caused the collapse of the northern hemisphere ice shelves and the consequent release of a prodigious volume of icebergs (bond & lotti, 1995; hemming, 2004, among others). pollen studies have shown that lgm was characterized by humid conditions in southwestern europe, allowing the development of arboreal vegetation, a factor that further distinguishes it from the mis 2 heinrich events, during which there was a notable predominance of semiarid vegetation (fletcher & sánchez–goñi, 2008; kageyama et al., 2005; peyron et al., 1998). likewise, faunal assemblages (small and large mammals) shows for the lgm in the iberian peninsula the presence of numerous temperate taxa, such as cervus elaphus, capreolus capreolus or vulpes vulpes (sommer & nadachowski, 2006). indicating that iberia acts as glacial refugia for the temperate species. in the light of this brief environmental characterization, the present study applies a bioclimatic model (following hernández-fernández, 2001a, 2001b) to the analysis of the rodent assemblages of the lagar velho rockshelter, located in the lapedo valley (leiria, portugal). the aim is to infer various climatic parameters, which will be further compared with the present climatic data, taking into account the available studies of the lgm and h3 small-vertebrate assemblages. https://doi.org/10.26382/amq.2021.04 202 lópez-garcía j.m. et al. fig. 1 1 and 2: location of the main sites mentioned in the iberian peninsula, including the lagar velho rockshelter (2). 3: plan of the lagar velho rockshelter showing the location of lv1 burial. 4 and 5: the hanging remnant (tp) with the position of tp06 and tp09 (courtesy of joão zilhão). 203 2. the lagar velho site and the lapedo child the lagar velho rockshelter (abrigo do lagar velho-alv; 30°45’25”n; 8°43’58”w) is located in the lapedo valley in the municipality of leiria, about 135 km north of lisbon (fig. 1.1,1.2), on the left bank of the caranguejeira stream. it was first discovered and excavated in late 1998, soon after the identification of the lv1 infant burial (duarte et al., 1999). the top two/three metres of sediment overlying the burial had previously been removed by the shelter-owner by mechanical means; all that survived was a profile trapped inside a recess in the back wall of the shelter and labelled “hanging remnant” (testemunho pendurado / tp in portuguese; henceforth tp; fig. 1). on the one hand, levels tp09 and tp06 (see fig. 1), which contain the small-mammal remains analysed in the present study, are included in the upper slope deposits (us), defined during the 1998 and 1999 investigations (angelucci, 2002 in zilhão & trinkaus, 2002). the us sedimentary complex preserves traces derived from archaeological occupations that took place at alv between the terminal gravettian (level tp06) and the middle solutrean (level tp09) (zilhão & almeida, 2002). these units are in general characterized by a coarse sedimentary component of angular limestone slabs originating from the shelter wall, and by a finer component of sandy silts and clayey silts rich in anthropogenic remains (angelucci, 2002). registered in the lower part of the us complex, level tp06 (fig. 1.4) is characterized by sandy, dark browngrey sediment with limestone clasts, with a maximum thickness of ca. 30 cm. it contains a much higher amount of archaeological remains than the overlying level tp09. radiocarbon dating suggests that it was deposited between 25976-24955 cal yr b.p. (using the most consistent 14c date of 21180±240 b.p.; pettitt et al., 2002; tab. 7-4). level tp09 (fig. 1.5) is chaotically arranged in terms of its inclination and orientation. it comprises numerous limestone blocks and platelets of various dimensions, detached from the shelter wall by mechanical or cryogenic action. it has a maximum thickness of approx. 18 cm. the finer component consists of thin sands of a light cream colour, sometimes whitish, especially at the top in contact with the limestone, indicating some later carbonation of this deposit. charcoal appears in large amounts and is ubiquitously distributed; faunal remains, also very numerous, show a relatively poor state of conservation. this unit is 14c dated to 20200±180 (pettitt et al., 2002, table 7-4), i.e. 2490623877 cal yr b.p., 95% confidence (tab. 1; fig. s1). on the other hand, the upper fine gravel and sand complex (gs) analysed in the framework of the present study was identified immediately under the artificial surface created after the bulldozer terracing and corresponds to the sedimentary layer where the infant was buried (fig. 1.3). the burial was a single episode involving a complex and careful ritual (duarte, 2002; zilhão, 2005). the small mammal recovered in this sedimentary unit was not directly related to the burial, but to the sediments that accumulated in the level where the grave was opened. radiocarbon dating of the burial has provided four 14c dates from remains accompanying the burial, giving a range between 27637-29407 cal yr b.p. (pettitt et al., 2002; zilhão & almeida, 2002) (tab. 1; fig. s1). another 14c sample from the bs/tc complex interface, i.e. around 1m below the sepulchre, gives a range between 31278-30191 cal yr b.p. (tab. 1; fig. s1). therefore, the small mammals date to between the burial event (ca. 29.4-27.6 kyr b.p.) and the age obtained for the underlying layer (ca. 31 kyr b.p.). 3. material and methods 3.1. small-mammal sorting, palaeontological and taphonomic studies and palaeoenvironmental reconstruction the small-mammal fossil remains used in this study come from layers tp06, tp09 and from the sediments where the lv1 child was buried, in the upper gs complex. the assemblage consists of disarticulated bone fragments collected in a very small volume of sediments (ca. 1 m3), although this is extremely rich in faunal remains. sediments from the tp layers were water-sieved through a 2.5 mm mesh in the field (moreno-garcía & pimenta, 2002), whereas the sediments from the child burial were water-sieved through a 1.5mm mesh in the laboratory (moreno-garcía, 2002). a preliminary smallmammal list was published by moreno-garcía & pimenta (2002), and a revision was recently undertaken in january 2020 at the laboratório de arqueociências (larc) in lisbon, during a short stay by the corresponding author. the assemblage under study is small and includes a total of 135 identified remains, corresponding to a minimum number of 75 individuals belonging to 11 different taxa (tab. 2; fig. 2). the fragments were identified at larc following the general criteria of systematic palaeontology (appendix s1). specific identification was based principally on the best diagnostic elements, such as mandible and maxilla for shrews and hedgehogs; first lower molars for the subfamily arvicolinae; and mandibles and maxilla for the subfamily murinae. specimens were grouped using the minimum number of individuals (mni) method, determined by counting the most diagnostic element of each species by layers. following andrews (1990) and fernández-jalvo et al. (2016), alterations caused by digestion in the first lower molars of the arvicoline rodent species were observed, but a probable bias in the methodology of collecting the samples small mammals from lagar velho rockshelter tab. 1 radiocarbon results for tp06, tp09 and child’s burial sediments modified from pettitt at al. (2002) and calibrated using oxcal 4.2.4 software (bronk ramsey, 2009) and the intcal’13 curve (reimer et al. 2013). 204 lópez-garcía j.m. et al. fig. 2 some small-mammal material identified from the studied levels of lagar velho. a. left mandible sorex sp. (buccal view); b. left mandible crocidura cf. suaveolens (buccal view); c. left m2 talpa cf. occidentalis (buccal view); d. right m1 arvicola sapidus (occlusal view); e and f. left and right m1 microtus agrestis (occlusal view); g and h. two left m1 microtus arvalis (occlusal view); i and j. right and left m1 microtus (iberomys) cabrerae (occlusal view): k and l. right and left m1 microtus (terricola) lusitanicus (occlusal view); m and n. left m1 and m1 apodemus sylvaticus (occlusal view). scales 1 mm. small mammals from lagar velho rockshelter 205 precluded a quantitative taphonomic interpretation. this is because the screen meshes both of 2.5 mm used for the tp layers and of 1.5 mm used for the child burial were too large to recover certain small microvertebrate elements considered relevant to this research. this comes to light through the absence of isolated teeth belonging to small taxa such as a. sylvaticus or s. cf. granarius (appendix s1). finally, the application of quantitative palaeoenvironmental methods such as habitat weightings (see evans et al., 1981; andrews, 2006) was also ruled out by the methodological bias of the sample collecting. however, we took into account the current habitat preferences of the identified species for our interpretation and discussion, using the published works of palomo et al. (2007) and bencatel et al. (2017). 3.2. palaeoclimatic reconstruction considering the bias recovering the small-mammal and the low number of small mammals remains recovered, quantitative methods have been avoided. then we used a method for the obtention of climatic parameters based on the faunal list. after that, to reconstruct the climatic conditions at alv during the above-mentioned human occupations we used the bioclimatic model (hernández-fernández, 2001a and b). this method is based on the hypothesis that a significant correlation exists between climate and mammal communities. the rodent assemblage from the three analysed layers at alv corresponds to four of the ten climatic types described by hernández-fernández (2001a and b), hernández-fernández & pelaez-campomanes (2005) and hernández-fernández et al. (2007): iv, subtropical with winter rains and summer droughts; vi, typical temperate; vii, arid temperate; and viii, cold temperate (boreal). the assemblages were analysed using the climatic restriction index (crii= 1/n, where “n” is the number of climatic zones where the species are represented and “i” is the climatic zone where the species appears) (table 3). the bioclimatic component (bc; representation, by level, of each of the four represented climates) was then calculated using the following formula: bci=(∑ crii) x 100/s, where s is the number of species per unit of each site (tab. 3). from bc, a mathematical model was elaborated using a multiple linear regression (hernández-fernández & peláezcampomanes, 2005). by means of a series of functions, this yielded estimates for the mean annual temperature (mat), the mean temperature of the coldest month (mtc), the mean temperature of the warmest month (mtw) and the mean annual precipitation (map) (table s1). a comparison was drawn with 30-year climatic data (from climate-data.org) from the meteorological station of leiria (leiria, portugal), located at 36 m above sea level (a.s.l.), with mat=15.9°c, mtw=21.1°c, mtc=10.8°c and map=790 mm. to place our data in a global context, we used the köppen-geiger climatic classification (köppen & geiger, 1936), with updates according to peel et al. (2007) and beck et al. (2018). this classification is based on mean annual and monthly temperatures and precipitation, using the native vegetation to determine the climate types. tab. 2 representation of the small-mammal material identified from the lagar velho rockshelter. nisp is the number of identified specimens; mni is the minimum number of individuals; and % is the percentage of mni. tab. 3 distribution of the rodent species identified from the different analysed sites according to their climate preferences, in accordance with hernández-fernández (2001b) and hernández-fernández et al. (2007). iv subtropical with winter rains and summer droughts; vi typical temperate; vii arid-temperate; viii cold-temperate (boreal). cri: climatic restriction index; bc: bioclimatic component. 206 lópez-garcía j.m. et al. tab. 4 relation of temperatures and precipitation for the different studied layers; mat, mean annual temperature; mtw, mean temperature of warmest month; mtc, mean temperature of coldest month; map, mean annual precipitation; present-day values from the leiria meteorological station; δ: di erence between the values obtained by analysing rodents from the different sites and the present-day mean. fig. 3 chronological position of the studied levels of lagar velho (x axis) in relation to the benthic 18o (y axis) isotope curve (modified from lisiecki & raymo, 2005). 4. results and discussion 4.1. the small-mammal composition of the lagar velho rockshelter and some palaeoenvironmental remarks the small-mammal remains recovered from the different layers of the lagar velho site are scarce, but the number of identified species is relatively high, with at least ten taxa. from the point of view of the presence / absence of species, the small-mammal composition is very constant, with the three studied layers showing few differences (tab. 2). erinaceus sp. is present in the upper part of the gs complex where the child was buried, whereas talpa occidentalis and sorex sp. are absent. in level tp06 erinaceus sp., microtus arvalis and also sorex sp. are absent, whereas in tp09 the only absent species is erinaceus sp. (tab. 2). from a quantitative point of view (although this should be taken with caution due to the scarcity of remains), the sediment excavated in the upper gs complex possesses the greatest representation of the small-mammal assemblage (tab. 2), with arvicola sapidus, microtus (terricola) lusitanicus and apodemus sylvaticus being identified. these three species are widely distributed nowadays in portugal, and their relative abundance indicates an open forest and relatively humid conditions with stable water courses surrounding the site (paupério et al., 2017). arvicola sapidus, microtus (terricola) lusitanicus, microtus agrestis and apodemus sylvaticus, identified in layer tp06, represent almost 85% of the small-mammal assemblage (tab. 2). of these four species, microtus agrestis occurs almost exclusively in the north and centre-north of portugal (paupério et al., 2017), but it is also widely distributed in the northern part of the iberian peninsula from galicia to the pyrenees (palomo et al., 2007). their relative abundance in tp06 indicates open forest with relatively humid conditions and stable water courses in the vicinity of the site. the dominant species in tp09 are the same as in tp06, representing almost 80% of the smallmammal assemblage, although unlike in the previous layer microtus arvalis is represented (tab. 2). microtus arvalis is currently found in the extreme northeast of portugal (paupério et al., 2017) and may indicate drier conditions during the accumulation of layer tp09. other proxy studies conducted on the archaeological remains, e.g. studies of the archaeobotanical and other vertebrate taxa, indicate the following: 1) that the charcoal documented in the child burial shows a lower degree of preservation, but there are specimens belong to pinus sylvestris s.l. (queiroz, 2002); 2) that analysis of the pollen recovered from the excavation pit under the child burial does not provide a basis for palaeovegetation and palaeoenvironmental reconstruction (queiroz et al., 2002); and 3) that oryctolagus cuniculus represents more than 85% of the faunal assemblage identified in the burial (moreno-garcía, 2002). for layers tp06 and tp09, however, the presence/absence of certain types of charcoal reflects both the local vegetation and the choices of the human groups. no major differences were detected between layers and samples. the species pinus sylvestris, erica arborea, cytisus scoparius and ulex sp. represent at least 80% of the total assemblage. the scots pine is the dominant arboreal taxon, indicating an open, forested landscape without evidence of mediterranean-type vegetation (queiroz et al., 2002). this pattern partially coincides with our small-mammal data, where open forest is well represented in both tp layers by apodemus sylvaticus and microtus (terricola) lusitanicus. in addition, the largemammal assemblage identified in tp06 shows a predominance of horse (equus sp.), followed by red deer (cervus elaphus) and hare (lepus sp.), indicating the occurrence of more open spaces of a grassland type. the abundance of the above-mentioned species in tp09 is accompanied by an increase in wild boar, the occurrence of roe deer and lynx, and a decline in hare relative to tp06. these data suggest an increase in forest cover compared to the fauna recovered from the sediments underlying the burial grave (moreno-garcía & pimenta, 2002). the large-mammal data for the tp units coincide with a slight increase in the representation of small-mammal species associated with forest requirements, such as apodemus sylvaticus, from layer tp06 (where this species represents 11.5% of the small -mammal assemblage) to layer tp09 (where it represents 14.7% of the small-mammal assemblage). statistically, application of the chi-square test to the smallmammal taxa represented in both units and the mni shows there to be no significant differences in the smallmammal composition between tp09 and tp06, yielding the same probability p (same)= 0.7998. 4.2. palaeoclimatic reconstruction the 14c results obtained for the two tp units and the child burial (zilhão & almeida, 2002) suggest that the burial may have occurred between heinrich event 3 (he 3) and interstadial 4 (is 4), and tp06 and tp09 during the last glacial maximum (lgm) (fig. 3). using the rodent assemblage to compare the lagar velho data with current climatic data (tab. 4), the bioclimatic model points to conditions that were cooler (∆mat between -2.58°c and -2.56°c) and dryer (∆map between -488 mm and -126 mm) for all studied layers. the thermal gradient between summer and winter was higher than at present (∆mtw between +1.58°c and +2.65°c; ∆mtc between -7.87°c and -6.12°c), providing a more continental-temperate climate (warm summers, very cold winters and low rainfall) than presentday conditions, which are characterised as mediterranean oceanic (mild summers and mild, rainy winters). indeed, in terms of the köppen-geiger climatic classification (modified from peel et al., 2007 and beck et al., 2018), the current climate at leiria is considered csb (mediterranean oceanic), with mtw values not exceeding 22°c and mtc above 0°c , whereas the climate projected from the alv rodent assemblage shows a dfa climate (continental temperate), with mtw values above 22°c and mtc below 0°c . these data may explain the coexistence of species with different ecological requirements that do not have an analogous distribution nowadays, according to sans-fuentes & ventura (2000) and lópez-garcía et al. (2010a). species with mid-european requirements such as microtus arvalis and m. agrestis appear together with species of strictly mediterranean requirements such as m. (iberomys) cabrerae. although the anthracological studies of layers tp06 and tp09 (queiroz et al., 2002) have shown no evidence of mediterranean species among the charcoal samples, the small-mammal assemblage points to the presence of mediterranean species such as the taxon m. (iberomys) cabrerae (tab. 2), albeit in low numbers. 4.3. lagar velho in the context of the iberian mis 2 the discovery at the time of an upper palaeolithic (late pleistocene) burial, highlighted the importance of the lagar velho rockshelter, which represented the evidence of the presence of modern humans in southern iberia during the mis 2 (duarte et al., 1999). chronologically similar, there are other mis 2 sites in the iberian peninsula where h3 and lgm have been detected on the basis of small-vertebrate studies. for h3 we found the galls carboners site located at montral (tarragona, northeastern iberia) (lópez-garcía et al., 2014), whereas for lgm we found various sites: layers c and b of l’arbreda cave in serinyà (girona, northeastern iberia) (lópez-garcía et al., 2015); maltravieso-chimeneas cave in cáceres (extremadura, western iberia) (bañuls-cardona et al., 2012); layer p1 of el portalón cave at sierra de atapuerca (burgos, northern iberia) (lópez-garcía et al., 2010b) and the lower unit of valdavara-1 cave in becerreá (lugo, northwestern iberia) (lópez-garcía et al., 2011). as expounded above, the scarcity of small-mammal remains may make climatic interpretations and correlations difficult. nonetheless, the qualitative climatic data obtained from the rodent association indicate that the underlying burial may have happened during a cool period, as is indicated by a lower mat (-2.58°c ) than at present. however, the conditions are a little milder than those detected for h3 in the galls carboners site, where the mat was 3.72°c lower than nowadays (fig. 4) (lópez-garcía et al., 2014). the interpretation of layers tp06 and tp09, situated chronologically within lgm (fig. 3), and their comparison with other sites of similar chronology seem more plausible. in general, all sites with smallvertebrate studies attributed to lgm are associated with cold climatic fluctuations characterized by mat lower than at present (fig. 4). however, those sites located in central-north and northwestern iberia with a greater oceanic and continental influence, such as el portalón small mammals from lagar velho rockshelter 207 p1 and valdavara-1-lu, have an mat that is more similar to present-day values in the area in comparison with other sites which also fall within lgm, such as our studied layers, maltravieso-chimeneas and l’arbreda cave layers c and b (fig. 4). we also found differences among these sites. whereas in maltravieso-chimeneas and lagar velho tp06 and tp09, the mat is very similar, in l’arbreda cave it is substantially lower (fig. 4). these differences can be explained by the smallmammal associations. according to sans-fuentes & ventura (2000) and lópez-garcía et al. (2010a), the small-mammal associations of the lgm layers of l’arbreda cave are dominated by species with mideuropean requirements such as microtus arvalis and microtus agrestis, along with an abundant representation of microtus oeconomus and a lower representation of apodemus sylvaticus (lópez-garcía et al., 2015). by contrast, the small-mammal association of maltraviesochimeneas is very similar to levels tp06 and tp09 of lagar velho, represented by a combined association of species with mid-european requirements, such as microtus arvalis and microtus agrestis, with others with mediterranean requirements, such as microtus 208 lópez-garcía j.m. et al. (iberomys) cabrerae, together with a relative abundance of apodemus sylvaticus (bañuls-cardona et al., 2012). 5. conclusions our review of the small-mammal material from the lagar velho rockshelter leads to the following conclusions: the species microtus (terricola) lusitanicus was identified during the present study, thus refining the previous identification placed within the duodecimcostatus-lusitanicus group. likewise, microtus arvalis and microtus agrestis were recognized both species being present in the reviewed layers. finally, microtus (iberomys) cabrerae, which had not previously been identified, is added to the taxonomic list. from a taphonomic point of view, although certain degrees of digestion were observed, especially in arvicoline molars, a probable methodological bias in the recovery of the samples, which saw the sediments from the tp layers water-sieved through a 2.5 mm mesh in the field and the sediments underlying the child burial water-sieved through a 1.5 mm mesh in the laboratory, fig. 4 comparison of the benthic 18o isotope curve (modified from lisiecki & raymo, 2005) from 32 to 16 ka with the absolute dating range of the analysed sites and the difference (δ) with respect to the present-day mean annual temperature (mat) obtained on the basis of the rodent assemblages of various sites. gc: galls carboners; arb: l’arbreda cave; mtv-ch: maltravieso-chimeneas; p1: el portalón; vlu: valdavara-1 lower unit; and chb, tp06 and tp09: the levels of lagar velho studied in the present manuscript. precludes a taphonomic interpretation of the association. this bias could be also affected the representation in the studied small mammals community. the same can be argued regarding the application of quantitative methods to an environmental reconstruction. the small-mammal assemblage suggests the presence of an open forest in the vicinity of the rockshelter, which is consistent with the data previously published based on charcoal and large mammals. although it has been taken with caution, the application of the qualitative method of the bioclimatic model to the rodent assemblage shows the different layers analysed at the lagar velho rockshelter to have a cooler and relatively drier climate than nowadays, marked by more rigorous winter temperatures and slightly milder summer temperatures. in the light of the chronological position of the lagar velho rockshelter (considering the small-mammal association of the studied layers), it can be seen that layers tp06 and tp09 present similar micromammal compositions to all the other sites with small-vertebrate studies that fall within lgm, reflecting cold climatic fluctuations and mean annual temperatures lower than at present. acknowledgements we want to thank prof. joão zilhão for his help and for the revision of the firsts drafts of the manuscript. we also want to thank rupert glasgow for reviewing the english language of the manuscript. in addition, we want to thank dr. e. luzi and an anonymous reviewer for their suggestions that improved the final version of the manuscript. this manuscript is part of a josé castillejo project (cas18/00095) of the spanish ministry of science, innovation and universities. j.m.l.-g and j.d. were supported by a ramón y cajal contract (ryc2016-19386 and ryc-2015-17667, respectively), and m. sanz by a juan de la cierva contract (ijci-201733908) with financial sponsorship from the spanish ministry of science, innovation and universities. references andrews p. 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(dir.), comportements des hommes du paléolithique moyen et supérieur en europe: territoires et milieux. eraul, liège, 231-241. ms. received: december 16, 2020 revised: february 8, 2021 accepted: february 28, 2021 avaiable online: march 15, 2021 small mammals from lagar velho rockshelter 211 212 microsoft word 00_indice_lm04.docx il quaternario it issn 039-3356 italian journal of quaternary sciences 24 (1), 2011121-129 late pleistocene and holocene bats of latium (central italy) leonardo salari1 & tassos kotsakis2 1 dipartimento di scienze della terra, università di roma sapienza, roma 2 dipartimento di scienze geologiche and centro di ecologia evolutiva, università di roma tre, roma correspondent author: t. kotsakis <kotsakis@uniroma3.it> abstract: salari l. & kotsakis t., late pleistocene and holocene bats of latium (central italy). in this paper the late pleistocene and holocene fossil and subfossil bats collected in latium have been examined. seventeen taxa belonging to eight genera and to four families were reported in the list of fossil species (the presence of three additional species in the fossil assemblages is dubious). fifteen of them are reported as living today in the region. exceptions are the boreal species myotis dasycneme and eptesicus nilssonii. on the other hand the presence in latium of myotis mystacinus and barbastella barbastellus after 1980 is dubious. the majority of the fossil remains of bats collected in the sites of latium (especially in terms of number of specimens) belong to troglophilous species, forming reproductive and/or hibernating colonies in caves (rhinolophidae, myotis myotis, m. blythii, m. capaccinii and miniopterus schreibersii). bats roosting in trees or rock fissures (nyctalus noctula and tadarida teniotis) or visiting the caves only during colder winters (myotis bechsteinii and members of the genera pipistrellus and hypsugo) are quite rare. during the colder stages of the late pleistocene, the coastal regions of latium must have played the role of refugia for animals and plants, as testified by several thermophilous mediterranean sensu stricto species of bats, e.g. rhinolophus euryale, m. capaccinii, pipistrellus kuhlii, m. schreibersii and t. teniotis. riassunto: salari l. & kotsakis t., chirotteri del pleistocene superiore e dell’olocene del lazio (italia centrale). in questo lavoro vengono esaminate le associazioni fossili e subfossili a chirotteri del pleistocene superiore e dell’olocene della regione lazio. sono state individuate diciassette specie appartenenti a otto generi e quattro famiglie (la presenza di ulteriori tre specie è dubbia). quindici di queste specie vivono attualmente nella regione. sono assenti le specie boreali myotis dasycneme e eptesicus nilsonii. d’altra parte la presenza nel territorio della regione lazio di myotis mystacinus e barbastella barbastellus dopo il 1980, è dubbia. la maggioranza dei chirotteri raccolti nei siti fossiliferi laziali (in particolar modo se si considera il numero degli individui classificati con certezza) appartiene a specie troglofile che formano colonie riproduttive e/o ibernanti in grotte (rhinolophidae, myotis myotis, m. blythii, m. capaccinii e miniopterus schreibersii). specie viventi sugli alberi o in fessure (nyctalus noctula e tadarida teniotis) oppure che visitino le grotte solamente durante gli inverni particolarmente freddi (myotis bechsteinii e i membri dei generi pipistrellus e hypsugo) sono piuttosto rare. durante gli stadi freddi del pleistocene superiore almeno due specie boreali hanno fatto la loro comparsa nel lazio ma, d’altra parte, le regioni costiere del lazio devono aver svolto il ruolo di area rifugio come testimonia la presenza di molte specie termofile, mediterranee sensu stricto, nei vari siti fossiliferi (rhinolophus euryale, m. capaccinii, pipistrellus kuhlii, m. schreibersii e t. teniotis). key words: bats, late pleistocene, holocene, central italy. parole-chiave: chirotteri, pleistocene superiore, olocene, italia centrale. 1. introduction bats are very useful for paleoecological reconstructions: they are flying insectivorous animals, and they rapidly react to climatic and environmental changes. they are also good indicators for reconstruction of hypogean microclimates. their abundance in the cave sediments testifies the absence or sporadic presence of prehistoric humans in these sites during the same timespan. instead, they have low value as biochronologic indicators and probably for this reason few people is interested to their systematic study. our aims are to point out palaeobiogeographical, palaeoecological, microclimate, human activity and, if possible, biochronological indications for the late pleistocene and holocene bat assemblages of latium. 2. materials and methods the paper discusses the fossil and subfossil records of the late pleistocene and early holocene bats of latium (fig. 1). it is a first attempt at a regional synthesis and it shows several uses in palaeontology of bat remains. the data were based on fossil assemblages directly investigated by the authors (grotta breuil, grotta barbara, grotta del fossellone, riparo salvini, grotta di cittareale, and grotta mora cavorso) or on material reported in the literature (grotta di sant’agostino and grotta polesini). the bats were collected from fossiliferous sites spanning from 55 ky bp (grotta sant’agostino) to less than 7 ky bp (grotta mora cavorso). data about the first (warm) stage of the late pleistocene (mis 5) are lack l. salari & t. kotsakis 122 fig. 1 location of the sites. ubicazione dei siti. ing. the fossil assemblages were assigned to four distinct time periods (from the oldest to the most recent one): 1) grotta di sant’agostino (tozzi, 1970) to the last stage of the first pleniglacial (last stage of mis 4 and beginning of mis 3); 2) grotta breuil (kotsakis, 1991; alhaique et al., 1996; salari & di canzio, 2009), grotta barbara (salari & di canzio, 2009 and unpublished data) and grotta del fossellone (unpublished data) to the last part of the interpleniglacial (final stages of mis 3 and beginning of mis 2); 3) grotta mora cavorso (salari et al., 2010, this volume), riparo salvini (zhuowei & kotsakis, 2008), grotta di cittareale (argenti et al., 2008) and grotta polesini (radmilli, 1974) to the late glacial (final stages of mis 2); 4) grotta mora cavorso to the early holocene (rolfo et al., 2009). in three caves, the fossil bats were associated with different lithic industries and/or cultural horizons: grotta barbara (mousterian and aurignacian), grotta del fossellone (mousterian, aurignacian and advanced upper paleolithic), grotta mora cavorso (final epigravettian and neolithic) (tabs. 1 and 2). for the numerical data of micro and macro faunas and the detailed stratigraphies of the various sites, see the literature cited. 3. systematic observations the fossil remains from the investigated sites of latium do not show major morphological and/or morphometric differences from living species. however, paleontologists are confronted with some issues raised by recent applications of modern bioacoustic and molecular biology techniques (combined with conventional ones based on morphological and morphometric criteria), which identified and/or erected new species. in particular, some subspecies or geographic varieties of species belonging to the genera myotis, pipistrellus and plecotus were elevated to the rank of good species, but the lack of sound morphometric data for their taxonomic determination did not permit to adequately assess them. the fossil remains potentially falling into the above taxa (e.g. pipistrellus pygmaeus, leach, 1825) and supposedly having the same variability as the one of pipistrellus pipistrellus (schreber, 1774), or those of the cryptic species of myotis mystacinus (kuhl, 1817) were attributed to the traditionally more known species, followed by sensu lato (s.l.) in accordance with “linee guida per il monitoraggio dei chirotteri” (agnelli et al. 2004) for reports of these taxa prior to 1999-2000. this is the case of m. mystacinus s.l. of grotta breuil and p. pipistrellus s.l. of grotta barbara. also the distinction between hypsugo savii and species of larger size of the genus pipistrellus is problematic. the morphology and size of the distal epiphysis of the humerus are identical (see felten et al., 1973) and the variability of the size of the lower tooth row largely overlaps. on the other hand the morphology and position of the upper incisors suggests a clear discrimination between the cranial remains of pipistrellus kuhlii (kuhl, 1817), those of pipistrellus nathusii (keyserling & blasius, 1839) and those of h. savii (see miller, 1912; lanza & agnelli, 2002) but as is known incisors are rarely recovered from fossil remains. in these cases (e.g. at riparo salvini), the fossil remains were attributed to hypsugo vel pipistrellus (zhuowei & kotsakis, 2008). conversely, at grotta barbara, two mandibular branches were ascribed to p. kuhlii (salari & di canzio, 2009), because the size of the lower tooth row (c-m3 alveolar length = 5.4 mm) lay close to the upper limit of the size range of p. kuhlii (miller, 1912; benda et al., 2003) and was not included in the overlap range between the above three species. the attribution of some remains of a “middle size” rhinolophus collected in grotta breuil is uncertain, because the morphology of the fragmentary specimens not allow to assign the fossils to specific level, and the dimensions are inside the range of both rhinolophus euryale blasius, 1853 and rhinolophus mehelyi matschie, 1901. 4. biochronological indications pleistocene bats appear to have a low value as biostratigraphic indicators. only two extinct species, both from the early and middle pleistocene, were discovered in italy (tata & kotsakis, 2005). the species known in the late pleistocene are all extant and, except for myotis dasycneme (boie, 1825), they are all currently distributed in italy (agnelli et al., 2004). m. dasycneme is reported from a few late pleistocene sites of north and central italy, always in “cold” assemblages, but is not reported in any of the few known holocene sites. hence, based on the occurrence of m. dasycneme at grotta di cittareale, the chiropteran assemblage was ascribed to one of the last cold stages of the late pleistocene, probably the younger dryas (argenti et al., 2008). late pleistocene and holocene bats of latium (central italy) 123 fig. 2 grotta breuil: a) nyctalus noctula, distal epiphysis of left humerus; grotta barbara: b) rhinolopus ferrumequinum, distal epiphysis of right humerus; c) pipistrellus kuhlii, fragment of right mandibular ramus, labial view; d) pipistrellus pipistrellus s.l., fragment of right mandibular ramus, labial view; grotta del fossellone: e) rhinolophus euryale, distal epiphysis of left humerus; f) myotis blythii, distal epiphysis of left humerus; g) myotis capaccinii, distal epiphysis of right humerus; h) eptesicus nilssonii, distal epiphysis of left humerus (h1 external, h2 internal, h3 dorsal views); i) miniopterus schreibersii, distal epiphysis of right humerus; riparo salvini: l) hypsugo vel pipistrellus, distal epiphysis of left humerus; m) tadarida teniotis, distal epiphysis of right humerus, processus styloideus broken; grotta di cittareale: n) myotis dasycneme, distal epiphysis of left humerus; o) myotis bechsteinii, distal epiphysis of right humerus; grotta mora cavorso: p) myotis bechsteinii, fragment of left mandibular ramus, labial view; q) rhinolophus hipposideros, skull, dorsal view. all the humeri are illustrated in external view. scale bar = 2 mm. grotta breuil: a) nyctalus noctula, omero sinistro, epifisi distale; grotta barbara: b) rhinolopus ferrumequinum, omero destro, epifisi distale; c) pipistrellus kuhlii, frammento di ramo mandibolare destro, norma labiale; d) pipistrellus pipistrellus s.l., frammento di ramo mandibolare destro, norma labiale; grotta del fossellone: e) rhinolophus euryale, omero sinistro, epifisi distale; f) myotis blythii, omero sinistro, epifisi distale; g) myotis capaccinii, omero destro, epifisi distale; h) eptesicus nilssonii, omero sinistro, epifisi distale (h1 norma esterna, h2 norma interna, h3 norma dorsale); i) miniopterus schreibersii, omero destro, epifisi distale; riparo salvini: l) hypsugo vel pipistrellus, omero sinistro, epifisi distale; m) tadarida teniotis, omero destro, epifisi distale (processo stiloide rotto); grotta di cittareale: n) myotis dasycneme, omero sinistro, epifisi distale; o) myotis bechsteinii, omero destro, epifisi distale; grotta mora cavorso: p) myotis bechsteinii, frammento di ramo mandibolare sinistro, norma labiale; q) rhinolophus hipposideros, cranio, norma dorsale. tutti gli omeri sono illustrati in norma esterna. scala della barra = 2 mm. l. salari & t. kotsakis 124 tab. 1 schematic synthesis of stratigraphy and chronology of the sites. schema stratigrafico e cronologico dei siti considerati. 5. palaeobiogeographical indications from the end of the pleistocene to the present, various animal species changed their home ranges. the majority of the bat species identified in the pleistocene horizons are still present in latium, except for m. dasycneme, m. mystacinus s.l., eptesicus nilssonii (keyserling & blasius, 1839), barbastella barbastellus (schreber, 1774) and possibly r. mehelyi (tabs. 2 and 3). today, m. dasycneme has its southernmost limit of distribution in north-eastern croatia and is regarded as an “accidental species” in italy: the only reported specimen likely erratic was captured in trento in 1881 (lanza & agnelli, 2002; agnelli et al., 2004). m. dasycneme fossils are known since the early pleistocene (gelasian = late villányian = middle villafranchian) in central-eastern europe (horàček & hanák, 1989) and signalled in some middle and late pleistocene and holocene sites of asia and central-eastern europe (horàček & hanák, 1989 with references; piksa & wołoszyn, 2001; ochman, 2003; ochman & wołoszyn, 2003; postawa, 2004; rossina, 2006). in italy, it is known in the late middle and late pleistocene of grotta del broion (veneto, pasa, 1953), riparo mezzena (veneto, bartolomei & pasa, 1980), grotta del vento (marche, esu et al., 1990), and (as we have seen in the previous paragraph) in the grotta di cittareale (latium, argenti et al., 2008). this locality is the southernmost limit of this species, even considering its distribution in the pleistocene. grotta del fossellone 3 (advanced upper palaeolithic) was attended by e. nilssonii, a northern species and the only one among all the bats in the world which reproduces even beyond the arctic circle (as far as 70° 25’ n) (rydell et al., 1994). its current range of distribution includes central and northern europe, extending from the northern balkans through the palearctic asia to sahalin, korea and japan (agnelli et al., 2004). currently, its southernmost limit of distribution in europe is the south-eastern alpine arch and the northern balkans, with isolated colonies in the rila mountains in bulgaria (hanák & horàček, 1986; agnelli et al., 2004). e. nilssonii fossils are known since the early middle pleistocene in poland (wołoszyn, 1987). during the late pleistocene and early holocene, this species settled in various sites of central europe and of the former soviet union (crimea, siberia, russian far east) (rydell, 1993 with references; horáček, 1995; popov, 2000; piksa & wołoszyn , 2001; ochman, 2003; ochman & wołoszyn, 2003; rossina, 2006) and only at grotta del broion (veneto) in italy (pasa, 1953). grotta del fossellone represents the southernmost limit of this species in europe, even considering its distribution in the pleistocene. boreal species, e.g. m. dasycneme and e. nilssonii presumably deserted the region and the peninsula owing to climate warming in the holocene. conversely, the absence of nemoral species, such as m. mystacinus and b. barbastellus, both distributed in most part of italy, is relatively recent (after 1980); this absence (if con late pleistocene and holocene bats of latium (central italy) 125 firmed) is likely to be due to progressive deforestation and intense urbanisation of the region in the last century. another interesting paleogeographic issue is the recent settlement of animal and plant species in central-northern europe. during the coldest periods of the late pleistocene and, namely, the last glacial maximum (lgm), the iberian and italian peninsulas and the balkans played the role of main glacial refugia for many “temperate” or “warm” animal and plant species, which then repopulated the rest of europe (stewart & lister, 2001; sommer & nadachowski, 2006; tříska, 2009). this phenomenon certainly involved the majority of european bats. considering only the stratigraphic successions supported by estimated radiometric dates, fahlke (2009) reported that: i) bats deserted the area north of the alps in the lgm; and ii) it was only in the first stages of the late glacial, during the bølling-allerød temperate oscillations, that eptesicus serotinus (schreber, 1774) timidly returned to the area, followed by plecotus auritus (linnaeus, 1758) and b. barbastellus. in effect, few other species, including myotis bechsteinii (kuhl, 1817), myotis nattereri (kuhl, 1817), myotis brandtii (eversmann, 1845), myotis daubentonii (kuhl, 1817), e. nilssonii and p. nathusii, are reported in the late glacial successions (horáček, 1995; ochman, 2003), while the other species now present in central-northern europe must have returned there only in the holocene (horáček, 1995; blant et al., 2008; ruedi et al., 2008; fahlke, 2009). even in some regions south of the alps (e.g. canton ticino), repopulation took place in the holocene (blant et al., 2008). in the late pleistocene, latium, and generally central-southern italy, hosted many species which are now largely distributed in central-northern europe, including rhinolophus hipposideros (bechstein, 1800), myotis myotis (borkhausen, 1797), m. bechsteinii, m. dasycneme, m. mystacinus, nyctalus noctula (schreber, 1774), e. nilssonii and b. barbastellus. additionally, especially in the coastal sites of latium, various species of mediterranean s.s. thermophilous bats, e.g. p. kuhlii, r. euryale, myotis capaccinii (bonaparte, 1837), miniopterus schreibersii (kuhl, 1817) and tadarida teniotis (rafinesque, 1814), cohabited with “cold” species, e.g. marmot, hamster, wolverine, ermine and steinbock, even in the relatively colder stages of the late pleistocene. grotta barbara 1 (mousterian) was inhabited by p. kuhlii, a thermophilous species which is very anthropophilous today (lanza & agnelli, 2002; agnelli et al., 2004). fossils of p. kuhlii are rare, with a few records in the late middle and late pleistocene and holocene in germany, russia and turkey (salari & di canzio, 2009 with references). p. kuhlii of grotta barbara is the first and, for the time being, the only occurrence in italy. 6. palaeoecological indications the favourite foraging environments of the identified species shed more light on the environment surrounding the investigated sites (tab. 3). moreover, settlements of species usually hibernating in hollow trees or rock fissures (n. noctula, e. nilssonii e t. teniotis) or, rarely, in caves (m. bechsteinii and members of the genera pipistrellus and hypsugo) may indicate periods of more adverse climate or particularly harsh winters. these climatic and environmental indications are usually consistent with those provided by the other identified taxa, especially ungulates and rodents, and may complement and/or extend the data provided by the other animal and/or plant taxa. for instance, in the most ancient strata (cuts 2416) of riparo salvini, myotis blythii (tomes, 1857) is dominant and followed by m. capaccinii and m. schreibersii. this infers that the surrounding environment was fairly open, with prairies alternating with sparse woods and wetlands. in the other cuts 15-7, m. blythii is still dominant and followed by rhinolophus ferrumequinum (schreber, 1774), hypsugo vel pipistrellus and n. noctula, suggesting similar but less humid environments and climatic transition from conditions similar to present ones to colder conditions. the paleoenvironmental clues given by bats match those provided by rodents. the latter passed from an assemblage with dominant microtus (terricola) savii (de selys-longchamps, 1838), followed by apodemus sylvaticus (linnaeus, 1758), arvitaxon / sites g ro tt a d i s . a go st in o g ro tt a b re u il g ro tt a b ar b ar a 1 g ro tt a d el f o ss el lo n e 1 g ro tt a b ar b ar a 2 g ro tt a d el f o ss el lo n e 2 g ro tt a d el f o ss el lo n e 3 g ro tt a m o ra c av o rs o 1 r ip ar o s al vi n i g ro tt a d i c it ta re al e g ro tt a p o le si n i g ro tt a m o ra c av o rs o 2 rhinolophus ferrumequinum x x x x x x x x x rhinolophus hipposideros x x x rhinolophus euryale x x x rhinolophus euryale/mehelyi x myotis myotis x x myotis blythii x x x x x x x x x myotis myotis/ blythii x x myotis capaccinii x x x myotis dasycneme x myotis bechsteinii x x myotis emarginatus x x myotis mystacinus s.l. x myotis sp. x pipistrellus pipistrellus s.l. x pipistrellus kuhlii x hypsugo vel pipistrellus x eptesicus nilssonii x nyctalus noctula x x barbastella barbastellus x miniopterus schreibersii x x x x tadarida teniotis x x x total taxa 2 12 5 1 2 1 6 2 7 5 5 4 tab. 2 late pleistocene and early holocene bats of latium. (for the spelling of the species names see simmons, 2005). quadro riepilogativo dei taxa del pleistocene superiore e olocene antico del lazio. (per l’ortografia dei nomi delle specie cf. simmons, 2005). l. salari & t. kotsakis 126 taxon latium fossil latium today hibernacula temperatures of hibernation foraging environment zoogeographical patterns rhinolophus ferrumequinum x x caves 7 12 °c mixed mediterranean s.l. rhinolophus euryale x x caves 10 12 °c woods mediterranean s.s. rhinolophus mehelyi ? caves 11 13 °c woods mediterranean s.s. rhinolophus hipposideros x x caves 4 12 °c mixed mediterranean s.l. myotis myotis x x caves 2 12 °c woods mediterranean s.l. myotis blythii x x caves 4 14 °c open mediterranean s.l. myotis capaccinii x x caves 4 15 °c woods mediterranean s.s. myotis dasycneme x caves, hollow trees 0 7 °c forests boreal myotis daubentonii x caves 0 10 °c forests boreal myotis bechsteinii x x hollow trees, caves 1 10 °c woods nemoral myotis emarginatus x x caves 5 9 °c miscellaneous mediterranean s.l. myotis mystacinus s.l. x ? caves 2 8 °c miscellaneous nemoral myots nattereri x caves 2 8 °c woods nemoral pipistrellus kuhlii x x buildings, rock fissures ? miscellaneous, anthropophilous mediterranean s.s. pipistrellus nathusii ? x rock fissures, buildings ? woods nemoral pipistrellus pipistrellus s.l. x x buildings, hollow trees 0 6 °c woods, anthropophilous mediterranean s.l. pipistrellus pygmaeus ? x hollow trees, buildings ? miscellaneous, anthropophilous nemoral ? hypsugo savii ? x buildings, caves ? miscellaneous, anthropophilous mediterranean s.s. eptesicus nilssonii x rock fissures, buildings -6 7 °c forests boreal eptesicus serotinus x buildings, caves 2 4 °c miscellaneous mediterranean s.l. nyctalus lasiopterus ? hollow trees -6 6 °c forests nemoral nyctalus leisleri x hollow trees ? woods nemoral nyctalus noctula x x hollow trees > -7 °c forests nemoral barbastella barbastellus x ? caves 0 8 °c forests nemoral plecotus auritus x hollow trees, caves 2 5 °c forests boreal plecotus austricus x caves, hollow trees 2 12 °c woods mediterranean s.l. miniopterus schreibersii x x caves 4 12 °c miscellaneous mediterranean s.s. tadarida teniotis x x rock fissures 0 10 °c rocky mediterranean s.s. tab. 3 late pleistocene and early holocene chiropteran taxa, extant bat fauna of latium and key ecological features (data from horáček et al., 2000; lanza & agnelli, 2002; agnelli et al., 2004; amori et al., 2009). (for the spelling of the species names see simmons, 2005). confronto tra i taxa del pleistocene superiore e olocene antico con l’attuale chirotterofauna del lazio, e schema sintetico di alcune caratteristiche ecologiche (dati da horáček et al., 2000; lanza & agnelli, 2002; agnelli et al., 2004; amori et al., 2009). (per l’ortografia dei nomi delle specie cf. simmons, 2005). cola amphibius (linnaeus, 1758) and eliomys quercinus (linnaeus, 1766), to an assemblage with dominant m. (t.) savii and microtus (microtus) arvalis (pallas, 1778), followed by a. sylvaticus, e. quercinus and a. amphibius together with chionomys nivalis (martins, 1842) (zhuowei & kotsakis, 2008). the species haunting woods and forests are always associated with cervids and/or glirids. t. teniotis (rupiculous species) is associated with the steinbock at grotta breuil, grotta barbara and riparo salvini. it is worth noting that: i) in the late glacial succession of grotta polesini (radmilli, 1974), in spite of difficulties in correlating the various trenches (alhaique & bietti, 2007), r. ferrumequinum and m. schreibersii disappears and b. barbastellus gradually increases upon the appearance of the marmot and of the wolverine; or ii) at grotta s. agostino (tozzi, 1970), upon the appearance of the rhinoceros (stratum a2), only m. blythii remains, accompanied by r. ferrumequinum in the underlying strata. in other instances, the paleoenvironmental indications given by bats are the only ones (e.g. at grotta di cittareale) or improve the understanding of available data, e.g. at grotta barbara and grotta mora cavorso. at grotta barbara 1 (mousterian), the percentage ratios between the identified cervids (red deer, fallow deer, roe deer) point to two different possible scenarios in the pontina plain: a relatively open environment with scarce or localised forest cover or diffuse mediterranean “macchia” (caloi & palombo, 1989). the dominance of m. blythii validates the former assumption. at grotta mora cavorso 2 (neolithic), ungulates include the red deer and domestic ruminants; only m. blythii shows that the upper aniene river valley and the simbruini mountains, too, were in part covered by prairies. late pleistocene and holocene bats of latium (central italy) 127 considering that only the lesser mouse-eared bat is indicative of open spaces and that various species populate miscellaneous or mixed environments, the only inconsistency concerns the most recent part of the mousterian succession of grotta breuil. among the ungulates of stratum 3, the steinbock prevails over the red deer, implying drier and colder conditions than in the underlying strata where the red deer prevails over the steinbock (alhaique & bietti, 2007). among bats, r. euryale is dominant, testifying a good forest cover and a temperate climate, more or less as in the underlying strata. this inconsistency may be redressed by: i) assuming that the fossil remains are not coeval (bats must have colonised the cave only after the mousterians deserted it, see later on); or ii) recalling the previous points made about the role of the coastal sites of latium as glacial refugia for various species of thermophilous bats. 7. microclimatic indications the microclimate of caves has a paramount importance in the selection of diurnal roosts or reproductive and hibernating environments. each species has its own tolerability to narrow ranges of temperature and humidity (generally low temperature and high humidity). nonetheless, the temperature and humidity of a cave may vary depending on its size and morphology, as well as on the number and orientation of its openings. large-sized caves may have a variety of microclimates (more or less constant temperatures but variable humidity, owing above all to draughts of air) and each species selects the sites which best suit its preferences. usually, bats have not been hunted by prehistoric humans for food or other purposes, but may be occasional preys of nocturnal raptors (strigiforms): in the pellets regurgitated by these raptors, bats account for as little as 1% of the preys, including rodents, small birds and insectivores (kowalski, 1990, 1995; sevilla garcía, 1998). hence, most of the fossil remains in the investigated sites are naturally accumulated bones of bats which died in their caves. the lack of juvenile remnants (suggestive of attendance in the spring or summer reproductive period), except for an immature specimen found at grotta breuil, suggests that the bats are died for poor subcutaneous fat reserve or other causes during hibernation. this is why the investigated thanatocoenoses can give further insight into the winter microclimate, at least around the excavated area. for instance, it may be assumed that: at grotta breuil (strata 6-3), the winter microclimate remained fairly constant (on average around 10-12° c) and with high humidity; the winter temperature fluctuated around 5-6° c at grotta barbara 1 (mousterian), around 7°c at grotta di cittareale and rose slightly at grotta mora cavorso (from roughly 7-10°c to 7-12° c) between the final stages of the late pleistocene and holocene (neolithic). 8. human activity indications today some species of bats, particularly of the genera pipistrellus and hypsugo are anthropophilous, living in the urban areas and roosting in the buildings (miller, 1912; lanza & agnelli 2002; agnelli et al., 2004). however the troglophilous bats are wild and are not commensal to humans and, usually, the occurrence of bat remains in the sediments of caves evidences the absence or sporadic presence of prehistoric humans in the time interval during which the sediments were deposited (rossina, 2006; salari & di canzio, 2009; salari, 2010). noise, light and heat from human attendance change hypogean environments. a particular source of disturbance to bats is the smoke from human fires, which may also alter the microclimate of caves. the disturbance is higher in winter or during the reproductive period and may cause the bats to desert the caves in search of more suitable ones (marsico, 2003; agnelli et al., 2004). it is perhaps not by chance that the percentage of bats at grotta breuil is almost specular to the percentages of traces of human activity left on the bones of large mammals (alhaique & bietti, 2007; alhaique, in litteris): peak of human activity corresponds to low bat attendance (stratum 7); a sharp drop in human activity is associated with a strong increase in bat attendance (stratum 6); scarce remains of bats and equally scarce human activity characterise strata 5 and 4; minimum of human activity in stratum 3 is indicative of peak of bat attendance (tab. 4). in stratum 3 can not be excluded that bats may have settled in the cave only after the mousterians abandoned it. tab. 4 percentages of the number of identified remains of large mammals, number of large mammals with traces of human activity and number of identified bat remains at grotta breuil (data from alhaique & bietti, 2007; salari & di canzio, 2009; alhaique in litteris). confronto tra il numero dei resti determinati dei grandi mammiferi, il numero di tracce di attività umana sui resti di grandi mammiferi ed il numero dei resti determinati di chirotteri di grotta breuil (in percentuale)(dati da alhaique & bietti, 2007; salari & di canzio, 2009; alhaique in litteris). the alternating attendance of caves by bats and humans may have been multi-year cyclical or seasonal (late spring-early autumn for humans, late autumn-early spring for bats). based on available data on seasonal human attendance of grotta s. agostino, grotta breuil, grotta del fossellone 2 (aurignacian), riparo salvini and grotta polesini (alhaique & bietti, 2007) multi-year cycles seem more likely. acknowledgements we are grateful to gianni amori and federico masini for the useful suggestions. we thank also the late amilcare bietti, francesca alhaique, emanuele di canzio, margherita mussi, mario f. rolfo and the “gruppo grotte pipistrelli cai terni” for their support and who have allowed the access to the bat remains. l. salari & t. kotsakis 128 references agnelli p., martinoli a., patriarca e., russo d., scaravelli d. & genovesi p. 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(2008) tardiglacial micromammals of riparo salvini (latium, central italy). geol. romana, 41, pp. 125-132. ms. ricevuto il 13/10/2010 testo definitivo ricevuto il18/01/2011 ms. received: october 13, 2010 final text received: january 18, 2011 amq62 giraudi.pub �� � �available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 30 (2), 2017, 93-103 the morphology of the base of the alluvial sediments of the vercelli plain (piedmont, nw italy): an integration of the knowledge on the quaternary geological evolution carlo giraudi enea c.r. saluggia, saluggia (vc), italy corresponding author: c. giraudi <carlo.giraudi@enea.it> abstract: the southern vercelli plain lies on the top of the westernmost apennine thrust front (monferrato thrust front). according to previous studies, it is interested by quaternary tectonics and, despite the absence of historical earthquakes, could be affected by ml 6 earthquakes. however the lack of middle pleistocene river sediments and terraces in the southern part of the plain prevents any knowledge of the geological evolution for a period that lasted about 600-700 ka and limits the data useful to establish the seismo-tectonic characteristics of the monferrato thrust front and to establish the seismic hazard. using the data derived from studies carried out in the 70s and 80s of the 20th century in order to localize a nuclear power plant, including field surveys, the drilling of dozens of boreholes, geophysical surveys, and hydrogeological studies of superficial waters and aquifers, and also data on the base of the unconfined aquifer, it has been possible to evidence the morphological features of the surface that lies at the base of the alluvial sediments. the data indicate that in the southern vercelli plain there are small valleys and ridges covered by alluvial sediments, originated by erosion connected with the alpine rivers and local streams, that do not show any evidence. the pattern of the buried ridges and valleys appears to be influenced by tectonic movements along faults that, only in part, correspond to the monferrato thrust front and transverse deformation zones active until the middle pleistocene. only for a small area, the buried drainage network flowed towards a karst system developed in messinian gypsum. keywords: quaternary, geological evolution, alluvial sediments, buried morphology, salt-karst in gypsum, vercelli plain, piedmont, italy. 1. introduction the present work aims at a more complete definition of the geological evolution of the vercelli plain. the succession and distribution of fluvial terraces in this area indicate the presence of quaternary tectonics (gsqp, 1976; enel, 1984; giraudi, 2014) and the relationship between the hydrographic network and the buried tectonic structures of the apennines thrust front (monferrato thrust front) are similar to those known in the easternmost apennines front (bonadeo et al., 2010; burrato et al., 2012; michetti et al. 2012; livio et al., 2015). however, unlike the other sections of the front, the vercelli plain is characterized by extremely low seismicity, represented by very few earthquakes with local magnitude < 3 and also with their hypocentre located at depths exceeding 50 km (rovida et al., 2011; rsni, 2014a, b). in the southeastern part of the plain, geodetic studies (arca and beretta, 1985) have also documented an uplift rate of more than 4 mm/year-1 between 1897 and 1957 ad, a period without earthquakes. according to michetti et al. (2012), the vercelli plain could be a seismic gap area, where the magnitude of the earthquakes could reach values close to ml6. published studies have provided information on the geological evolution of the area and on the shaping of the fluvial terraces since marine isotopic stadium (mis) 22, according to giraudi (2014). while near the edge of the hills the terraces were formed only during the late pleistocene and holocene, in the northernmost area there are six older terraces dated between the late early pleistocene and the late middle pleistocene. it follows that in the plain near the hills, the age of the terraces allows the evolution to be assessed only since the late pleistocene (fig. 1a). in fact, in the late early pleistocene and the early middle pleistocene, alpine rivers that shaped the oldest terraces abandoned the area nearest to the hills and migrated north, and only in the late pleistocene returned to occupy the southern area (giraudi, 2014). the lack of glaciofluvial and fluvial sediments (from now on “alluvial sediments”) and terraces thus prevents any evaluation of the evolution of the southern plain for a period of about 600-700 ka. the purpose of this study is to fill this knowledge gap and recognize at least some of the phases of the geological and morphological evolution that occurred before the late pleistocene and to outline the evolution of the area since the end of the lower pleistocene. � �� � � 94 giraudi c. 2. methods to achieve the goal of outlining the geological evolution of the area since the end of the lower pleistocene some stratigraphic and morphological data were taken into account. the strong variations in thickness of the sediments of alluvial origin have been evaluated over the vercelli plain lying near the northern edge of the monferrato. the sediment thickness variations are derived from enel (1984) and from the stratigraphic data reported in the data-base of the piedmont region, and in particular from the map of the base of the unconfined aquifer (regione piemonte, 2004). the shape of the surface lying at the base of the alluvial sediments, showing gentle ridges and depressions, was compared with the morphology of the valleys in the adjacent monferrato hills, reported in the carta tecnica of the piedmont region at 1:10, 000 scale, in order to check any similarities, and with the direction of known tectonic structures, definitively active during the early and middle pleistocene (giraudi, 2014; 2016), in order to detect any tectonic constraints. in particular, when the remnants of the depressions have similar directions to those of the main tectonic structures on which, or near which, they are located, or when significant changes occur in the buried drainage in correspondence with tectonic structures, it has been assumed that tectonics have influenced, directly or indirectly, the evolution of the drainage network that shaped fig. 1 morphological and tectonic sketch of the vercelli plain between the rivers dora baltea, po, and sesia. 1a fluvial and fluvioglacial terraces forming the vercelli plain. s1-s3: terraces forming the trino isolated hill (rit); s4-s8 terraces shaped by alpine rivers when their beds were far from the present ones; t9-t11: terraces forming a belt near the present-day alpine river beds; l1-l2: terraces shaped by local streams. � �� � � 95 the morphology of the base of the alluvial sediments of the vercelli plain (piedmont, nw italy): …. the buried surface. the position of the thrust front and of the structures connected with it, assumed in the present paper, have been discussed in giraudi (2014; 2016). in those papers it was observed that the various models, inferred from the geophysical data, if considered in detail, overlap only partially the structures indicated by the field and borehole data: therefore in the present paper are reported only faults and deformation zones that have been evidenced by field researches and borehole data and that show a clear post-pliocene activity. the chronological framework of the erosion phases that shaped the surface on which the alluvial sediments lie is based on the age of the sediments on which the fig. 2 isobaths of the base of the unconfined aquifer and morphological and geological features buried by the alluvial sediments. 2amap of the isobaths of the unconfined aquifer (modified from regione piemonte, 2004) and morphological features buried by alluvial sediments. a1 thickness of the alluvial sediments dated between ca 870 ka bp and the present (from giraudi, 2014). 2b interpretation of the morphological features at the base of the unconfined aquifer, comparison between the direction of the valleys covered by alluvial deposits and of some valleys and streams in the nearby hills, correlations between morphological features and tectonic elements, and age of the sediments that form the buried monferrato. �� � � surface lies and of the sediments that seal it, and on a comparison with the shaping of the oldest terraces, for which we have dating elements. the age of the fluviolacustrine, fluvioglacial and fluvial sediments, discussed in giraudi (2014; 2016), is based on palaeomagnetic data, on the presence of a tephra layer (reported in enel, 1977; 1984), on the correlation with the nearby ivrea morainic amphitheatre, and on archaeological artefacts dating from the lower palaeolthic to the roman age. 3. geological outline of the southern vercelli plain the vercelli plain, mainly formed by sediments of the dora baltea, po and sesia rivers, extends southwards as far as the monferrato hills (fig. 1). in the 70s and 80s of the 20th century, the plain was the subject of thorough geological surveys in order to site a nuclear power plant (enel, 1977; 1984). the researches produced a wealth of data which, integrated with the most recent data, are subject to different interpretations. geological studies carried out between 1975 and 1984 (enel, 1977; 1984) were intended to improve knowledge of the tectonic evolution of the monferrato thrust front, that is, the westernmost of the apennine chain thrust fronts. the studies included geological and geomorphological field surveys, the drilling of dozens of boreholes up to 200 m deep, geophysical surveys using electric (fig. 2a) and seismic methods, and finally, the hydrogeology and the geochemical characteristics of surficial waters and aquifers. in more recent years, the review of the data has suggested some new interpretations that have increased our understanding of the pliocene-pleistocene geological evolution of the area enabling it also to confirm previous interpretations and to assume the presence of tectonic structures transverse to the front (fig. 1b), which sometimes affect also the neighboring hills (bigi et al. 1990; costa, 2003; giraudi, 2014; 2015; 2016). the vercelli plain is made up of a series of terraced sedimentary units, whose origin is mainly glaciofluvial and fluvial, that can be dated between ca. 0.87 ma ago and the present time (fig. 1a). according to the data reported in enel (1976; 1984) and giraudi (2014; 2016), in the southern plain the sediments are less than 20 m thick (fig. 2a) and cover a complex erosional surface that shapes the top of strongly deformed tertiary marine sediments, similar to those forming the monferrato hills (fig. 2b). the marine sedimentary units buried in the vercelli plain will be called, from now on, the buried monferrato. the buried monferrato also includes piacenzian marine sediments and gelasian littoral ones (enel, 1984; violanti and sassone, 2008; giraudi, 2016) that contour the oldest marine sediments and do not outcrop on the adjacent hills (fig. 2b). the sequence of tertiary sediments sampled in boreholes drilled in the buried monferrato deserves special attention because it helps to recognize the displacement produced by some tectonic structures. according to enel (1984), in the area north and south of the rit, the pre-pliocene sediments are represented by the late oligocene-early miocene marne di antognola formation and by late cretaceous and eocene ligurian units (complesso indifferenziato and casale monferrato formation) outcropping also in the neighbouring hills. in the area near fontanetto po, the sediments are messinian (post-evaporitic, evaporitic and pre-evaporitic) consisting also of layers of crystalline gypsum, both compact and laminated, and of conglomerates with pebbles of crystalline gypsum, which do not outcrop in the adjacent hills. the messinian sediments then, although not studied in detail, show a succession similar to that of some stratigraphic sections studied by clari et al. (2008) and dela pierre et al. (2016) in the piedmont tertiary basin, south of the monferrato. the marine sediments that form the buried monferrato (fig. 1b, 2b) and the early pleistocene fluviolacustrine sediments, lying north of the thrust front but close to the tectonic structures, can dip strongly towards the north and be affected by both low-angle and subvertical fault plains, sometimes with striae (giraudi, 2016). the activity of the monferrato thrust front lasted until the lower or middle pleistocene (gsqp, 1976; enel, 1977; 1984; cassano et al., 1986; costa, 2003; galadini et al., 2012; giraudi, 2014). instead, according to some authors the thrust front would still be active (bonadeo et al., 2010; burrato et al., 2012; michetti et al. 2012; livio et al., 2015). in giraudi (2014) it is observed that two areas near crescentino and trino, having their axis oriented approximately n-s, seems affected by a weak late pleistocene and holocene uplift, supporting the hypothesis, advanced by previous authors, that tectonics are still active. the uplift, however, occurred also north of the thrust front, in places subsiding during the main phases of activity of the structure (fig. 1b). the deformation of the sediments is connected to the activity of faults, i.e. the lucedio, cavourrina, and crescentino fault (lf, caf, and crf in fig. 1b), the fontanetto po, trino and salera line deformation zones (fdz, tdz and sldz of fig. 1b), and the crescentino and morano flexures (giraudi, 2014; 2016). according to costa (2003) a first fault, the position of which corresponds to the crescentino fault of the present paper, and a second fault, corresponding to the salera line deformation zone, acted as transpressive structures that cut across the buried fronts. the lucedio and cavourrina faults overlap only in part short stretches of two different thrust fronts evidenced by geophysical researches (enel, 1977; 1984; cassano et al., 1986; bigi et al. 1990), according to giraudi (2014; 2016). the displacement of tertiary and quaternary sediments produced by the faults indicate that, near the surface, they acted as normal faults that moved downward the sediments lying north. in the fontanetto po and trino deformation zones, the vertical component of the displacement produced the subsidence of the areas west of fontanetto po and east of trino. also the flexures lie only on some stretches of thrust fronts. thus, not knowing the real connection between the superficial and deeper tectonic structures, in the present paper, the evolution of the erosion surfaces 96 giraudi c. �� � � that shaped the buried monferrato will be compared only with the activity of faults, deformation zones and flexures, active during the quaternary, that have been characterized using borehole data and field observations, without any reference to the activity of the monferrato thrust front that could be more complex. some analysis of the deformation phases, of the age and sedimentary facies of the early and middle pleistocene lacustrine, fluvio-lacustrine and alluvial units lying north of the lucedio fault and in the cerrina valley syncline, in the monferrato hills (fig. 2b), have been discussed in giraudi (2016). the data enabled it to be hypothesized that the hilly area north of the cerrina valley and the buried monferrato lying between the hills and the lucedio and cavourrina faults, were involved in the same phases of migration toward north of the monferrato thrust front. the review of the stratigraphy of the boreholes reported by enel (1984) has shown that in some cases, in correspondence with the fontanetto po deformation zone (fdz fig. 2b), the tertiary sediments are affected by subvertical fault planes and that, in general, to the west of the deformation zone, the sediments (messinian, pliocene and early pleistocene littoral) are more recent than those located to the east (ligurian units, dated between the upper cretaceous and the lower-middle eocene, and marne di antognola formation, dated between the upper oligocene and the lower miocene). in addition, to the west of the fontanetto po deformation zone, both the contact between the pliocene and pre-pliocene sediments and the northern limit reached by the ligurian units are considerably further south than in the eastern area. these data confirm the presence of that deformation zone, suggested by giraudi (2016) on the basis of the correlation between the cavourrina fault segment oriented nne-ssw and a series of fault lines oriented approximately n-s and nne-ssw identified in the bed of the po, and also probably a left slip component. along the trino deformation zone (tdz in fig. 2b), postulated by giraudi (2016) on the basis of the correlation between the eastern branch of the cavourrina fault segment oriented nnw-sse and a series of fault lines oriented approximately n-s and nnw-sse identified in the bed of the river po, it can be observed that, to the west, the sediments (ligurian units, marne di antognola formation) are older than those located to the east (marine pliocene and early pleistocene). in addition, to the west of the trino defomation zone, the northern limit reached by pre-pliocene tertiary sediments, corresponding to the cavourrina fault, lies considerably further north than in the eastern area, suggesting a possible right slip component. to the north of the lucedio fault (fig. 3a), the oldest continental sediments lying in the area between the crescentino fault and the salera line deformation zone are strongly deformed, while w and e of these structures, the sediments are gently tilted northward (enel, 1984; giraudi, 2016). during the phases of activity of the lucedio fault, the buried monferrato was uplifted while in the subsiding northern basin a syncline evolved having its axis nearly parallel to the fault (pieri and groppi, 1981; enel, 1984; cassano et al., 1986). based on the difference between the elevations of the base, the different thicknesses and the age of the alluvial sediments north and south of the lucedio fault, said fault may have been active up to about 0.4 ma ago and the total deformation of the bottom of these sediments has been estimated as between 80 and 120 m (giraudi, 2014; 2016). the succession of quaternary sediments lying on the buried monferrato is represented by alluvial deposits which chronologically refer from about 0.87 ma ago to the present (giraudi, 2014). these sediments form ten different terraces (s1, s2, s3, s4, s7, s8, t9, l2, t10, t11 fig. 1a). the oldest terraces (s1-s3) form the rit, a ridge which rises 40-50 m above the surrounding plain (fig. 3b). the lower terraces incline mainly from west to east, only those ne of the rit inclining mainly from wnw to ese. north of the lucedio fault, early pleistocene fluviolacustrine deposits lie below alluvial ones that started to sediment during the mis 22 (giraudi, 2014; 2016). in this area, where the terraces s1, s2 and s3 are lacking, rivers formed three terraces (s5, s6, l1), lacking south fig. 3 the trino isolated hill (rit). 3a: geological section through the hill and the surrounding terraces. 3b: morphological features and buried and present-day divides (modified from giraudi, 2016). 97 � the morphology of the base of the alluvial sediments of the vercelli plain (piedmont, nw italy): …. �� � � of the fault, and sloping mainly from nw to se. 4. the buried morphology and the base of the unconfined aquifer since the enel (1984) studies, it is known that in the buried monferrato the base of the unconfined aquifer corresponds indisputably to the top of the marine sediments, mostly marl and clay, while in the area just north of the lucedio fault it generally corresponds to the contact between alluvial and fluvio-lacustrine sediments. the comparison of the thickness of river sediments reported in giraudi (2014), based mostly on the enel (1984) data, and the shape of the base of the unconfined aquifer reported on the piedmont region map (regione piemonte, 2004) confirms the previous data. the two maps (fig. 2a), albeit at a different scale and resulting from the processing of data of different origin, show a substantial accordance for the buried monferrato and the area located immediately to the north. also the data reported in irace et al. (2009), on a less detailed map, show a similar trend. in addition, the set of geophysical surveys and calibration boreholes carried out in the central area of the buried monferrato (enel, 1977; 1984) provided a reconstruction of the top of the marine sediments which confirms, with more detail (fig. 4a), the trend shown by the map of the regione piemonte (2004). the map of the base of the unconfined aquifer is thus taken as the basic document for discussion and interpretation of the main morphological features buried by the alluvial sediments in the southern portion of the vercelli plain, while the more detailed map of the rit and neighbouring areas (fig. 4) is used to discuss some specific features. it should first be noted that in fig. 2 the continuity of the isobaths of the base of the aquifer is interrupted by the presence of the po riverbed, which is eroding the monferrato hills and buried monferrato tertiary marine sediments, and acts as the southern boundary of the unconfined aquifer. in any case, in fig. 2a the stretches of the po riverbed with different characteristics have been highlighted: in the less incised ones the tertiary sediments occasionally outcrop, in the more eroded ones the same marine sediments constitute most of the riverbed; and finally the deeply incised riverbed, where also the river banks consist of tertiary sediments. the map of the depth of the base of the unconfined aquifer (fig. 2a) shows some elements of direct interest such as ridges and depressions covered by alluvial sediments. the most obvious buried ridge is oriented approximately west-east, and lies beneath the alluvial sediments of the rit: towards the east, it becomes less noticeable and takes an approximately nw-se direction, while to the west it takes a north-south direction. the southern edge of this ridge is cut by the po riverbed which, precisely in this area, is more incised. ridges are less evident nw of fontanetto po and near crescentino, but one of them, which lies ne of crescentino, divides into two a buried depression described below. among the depressions covered by alluvial sediments, the most obvious one runs from the area west of crescentino to costanzana, east of the rit, while a second one, the southernmost one, runs from morano po to the area north of casale monferrato. the first of these depressions is complex, with the presence, west of crescentino and north of the rit, of deeper closed basins separated from the rest of the depression by means of some buried ridges. other minor depressions lie near crescentino, fontanetto po, palazzolo and north of the rit. north of fontanetto po there is a small closed depression with its bottom lying some metres below the top of the buried monferrato in the surrounding area. the morphology of the top of the buried monferrato, corresponding to the base of the unconfined aquifer, in the fontanetto po area has been highlighted in detail by the use of a greater number of boreholes and geophysical surveys. fig. 4a, modified from enel (1984), shows that the morphology of the top of the marine sediment is very complex, being affected by gentle ridges and depressions. the more evident ridge is buried under the rit. two other major ridges are lying north of palazzolo, running from nw to se. there are also elongated depressions in various directions and, especially, in the area north of fontanetto po, there is a complex closed depression, corresponding to that observed in fig. 2a. a special case concerns the rit. the base of alluvial sediments which form the terraces s1 and s2, dating from the final stages of the early pleistocene (giraudi, 2014), fills a depression running n-s and then ne-sw, while the sediments that form the s3 terrace fill a depression (only partially preserved due to erosion) that seems oriented from nnw to sse. said direction is not very different, therefore, from that of the southernmost depressions. 5. the buried morphological features: interpretation and discussion the interpretation of the buried depressions and ridges (fig. 2a), is based on the comparison with the direction of the valleys carved by the streams on the hills, and on the relationship between the identified morphological features and the lithology of the tertiary sediments and the tectonic structures affecting the buried monferrato and the northernmost areas (fig. 2b). the comparison allows some immediate interpretations. the two stretches of the depression that extends from west of crescentino to the costanzana area (fig. 2b) nearly overlap a syncline, evidenced by geophysical data and wells for oil research, that was formed in the subsiding basin north of the lucedio fault during the pliocene and early pleistocene (montrasio et al., 1969; pieri and groppi, 1981; enel, 1984; cassano et al., 1986). the westernmost depression is almost parallel to the crescentino flexure, while the remaining stretch is almost parallel to the lucedio fault. the depression west of crescentino is a closed one, therefore it cannot have been produced only by river erosion but also by tectonic deformation. also the depression extending towards 98 giraudi c. �� � � � 99 fig. 4 detailed map of the isobaths of the base of the unconfined aquifer, and interpretation of the morphological features buried by alluvial sediments near the trino isolated hill (rit). 4amap of the isobaths of the base of the unconfined aquifer and buried morphological features. 4binterpretation of the buried morphological features, main tectonic structures active after 870 ka bp, upper cretaceous to early pleistocene marine sediments forming the buried monferrato. the morphology of the base of the alluvial sediments of the vercelli plain (piedmont, nw italy): …. �� � � costanzana, that overlaps a long stretch of the pliocene and early pleistocene syncline, does not correspond only to a river incision, subsequently filled by sediments, because it includes two smaller closed depressions that can be explained only by assuming a tectonic deformation. moreover, the western and eastern boundaries of the same depression lie in correspondence with the extension towards the northwest of the crescentino fault and with the salera line deformation zone. the subsidence of the area lying north of the lucedio fault suggests that between the early and middle pleistocene sedimentation prevailed over the erosion (giraudi, 2016). the second wide depression, which lies north and east of morano po, is almost parallel to the morano flexure, and nearly overlaps a post-pliocene syncline, evidenced by geophysical data and wells for oil research, that was formed in a basin north of the flexure (see geological sections in montrasio et al., 1969). the depression, filled by sediments dated since the mis 22 (giraudi, 2014), ends abruptly to the west and, if it had been produced only by the erosion of a river, it would have to continued toward west or nw. the depression north of the morano flexure starts just east of the salera line deformation zone while, as reported before, the depression that lies north of the rit ends in correspondence with the northern extension of the same deformation zone. therefore, the salera line deformation zone could also have played a role in influencing the evolution of the buried morphologies at its western and eastern edges. other linear depressions, smaller in size and having various orientations, run from marginal areas towards the axis of the main depressions: it follows that the smaller depressions were probably palaeovalleys weakly carved by local streams. in the area north of palazzolo and nw of trino the depressions run from nnw to sse and then bend e. the trend of these depressions appears similar to that of the valleys in the adjacent hills (fig. 2b). it is therefore likely that the shaping of the buried depressions observed in that area and of the valley in the monferrato was conditioned by the same tectonic and morphological forcing factors. the depressions lying between the fontanetto po deformation zone and the crescentino fault, show a sennw trend, while those observed west of the crescentino fault run towards the north, like the valleys in the adjacent hills. figure 2b shows some interpretations of the buried ridges. the main ridge present in the rit area and towards the hills is almost parallel to the cavourrina fault and the fontanetto po deformation zone. however, the ridge has an irregular shape, because it was affected by the erosion produced by the heads of catchment basins of small streams tributary to the main rivers. the secondary ridge located east and north of crescentino is aligned with the extension towards the northwest of the crescentino fault, at the boundary between the sediments gently deformed by the crescentino flexure and the sediments strongly deformed by the lucedio fault (giraudi, 2014; 2016). the more detailed data shown in fig. 4 confirm the presence of a main buried divide trending west-east in the rit area, which is connected to the stretch of the divide running south. that ridge lies at the northern and western margins of the area uplifted by tectonics along the cavourrina fault and the fontanetto po deformation zone, and is almost parallel to these structures. south of the rit, there are smaller buried divides trending nw to se, and separate buried valleys elongated from nw to se, then about west-east and, in some cases, wsw-ene. the valleys are the same already highlighted in the less detailed map of fig. 2, and confirm a trend similar to that of the valleys in the adjacent monferrato hills. in fig. 4 the differences in elevation between the various sections of the main divide can be observed: the divide reaches 180 m a.s.l. under terrace s1 of the rit and 148-146 m a.s.l. under terrace s3, while below the upper pleistocene and holocene sediments, forming the s7, s8, t9, t10 and t11 terraces, its elevation is between 146 and 132 m a.s.l. the buried divide, then, reaches the lower elevation near the margin of the hills, below the alluvial sediments of the most recent terraces, having been subject to fluvial erosion until the late holocene. the present summit elevation of the top of the divide may have been influenced not only by its original height and by the river erosion but also by sub-aerial erosion that occurred before the alluvial fill, and by tectonic uplift. in the absence of any alluvial cover, the divide was subject to sub-aerial erosion, but when covered, it ceased to evolve and its height can only have been influenced by tectonics. for a long time, while the main rivers flowed north of the rit, south of the isolated hill the stretch of the divide running n-s was not covered by river sediments, and thus underwent sub-aerial erosion. only in the initial phase of the late pleistocene, when diversion of the alpine rivers to the south of the rit occurred (giraudi, 2014), this stretch of divide began to be affected by more intense fluvial erosion and was then covered by alluvial deposits. the tertiary sediments that form the buried divide southwest of the rit are clearly cut into by a scarp elongated about w-e located exactly in correspondence with the escarpment between terraces s7 and s8 (fig. 1a; fig. 4b). it is clear that in this area the top of the divide was eroded during the late pleistocene, but that the erosion did not erase entirely the morphology shaped earlier. the small valleys carved in the buried monferrato, including those that drain into the fontanetto po endorheic depression, may have orientations similar to those of tectonic structures even when they are not exactly overlapping these. in any case, the valleys have orientations generally different from those of the alpine rivers (flowing mainly w-e) that shaped the late pleistocene and holocene terraces. the comparison between the shape and direction of the divide in the buried monferrato below the alluvial sediments and the current divide between the basins of 100 giraudi c. �� � � the po and of the stura stream in the adjacent monferrato hills (fig. 2b, box a) shows that they are very similar in shape and that their west-east stretches are parallel to the cavourrina fault, while those oriented approximately north-south are almost parallel to the fontanetto po deformation zones (fig. 2b, box a). this correspondence does not seems to be accidental because the buried monferrato and the monferrato hills consist of the same marine sediments and suffered a common displacement towards the north during the last phase of the thrust front migration (giraudi, 2016). also from fig. 2b (box b), it can be observed that a series of valleys in the monferrato, and the buried divide east of the rit, change direction becoming nw-se, as does the northern edge of the hills. as stated above, the directions of the hill streams and of the current and buried divides have a pattern very similar to that of the cavourrina fault, but fig. 2a (box b) also indicates that the main change of direction of the buried morphological features occurs just south of those affecting the lucedio fault and the axis of the depression parallel to the fault. the buried morphological and tectonic features assume a nnw-sse and nw-se direction on the northern and southern prolongations of the trino deformation zone, which corresponds to the eastern branch of the cavourrina fault (giraudi, 2016). in box c of fig. 2b, it is possible to note that, at the southern continuation of the salera line deformation zone, the northern edge of the hills, the valleys carved in the hills and in the buried monferrato, after a short west-east stretch, change direction, assuming a sw-ne or wsw-ene trend. overall, therefore, the trend of the buried valleys and divides on the buried monferrato is similar to that of the monferrato hills, as can be expected from areas that have undergone a common geological and tectonic evolution. the changes in the direction of the buried morphological features, of the drainage network and of the divides between the catchment basins, lie almost in correspondence with the most important tectonic structures surrounding the area between the lucedio fault and the cerrina valley, that was subject to the common geological evolution until 400 kyr ago, according to giraudi (2016). this general correspondence suggests that the drainage evolution was directly or indirectly conditioned by tectonics affecting the area until, at least, the last periods of activity of the lucedio fault. the most singular buried morphology occurs just north of fontanetto po: it is a closed basin which includes some small valleys that converge towards the deepest part of the depression. the direction of the longer valleys is mostly parallel to the fontanetto po deformation zone (nne-ssw), while two shorter valleys run nw-se. the parallelism between the longer valleys and the direction of the deformation zone suggests that their incision could have been influenced by tectonics. the closed depression, and the small drainage network that it contains, may have originally been a continuation to the nw of the valleys lying east of the buried divide, but later, the continuity of the valleys could have been broken by the activity of the fontanetto po deformation zone that produced the subsidence of the western area. however, the presence of messinian sediments (fig. 4b) with compact gypsum near the deepest part of the closed depression suggests a hypothesis that may be alternative or complementary to that presented above. the closed basin may have formed due to the development of salt-karst in the gypsum. the presence of a karst swallow-hole could have attracted the streams that carved small valleys. the presence of salt-karst in the gypsum and of small closed depressions that drain into the karst systems are known in the southern slope of the monferrato hills (fioraso et al., 2004) and confirms that the hypothesis of the presence of salt karst in the gypsum in the buried monferrato is quite likely. apart from the closed depression possibly produced by karst, the wider and longer buried ridges and depressions are superimposed or lie close to and are parallel to tectonic structures: it is thus assumed that the shaping of the buried morphology was directly or indirectly influenced by the tectonics. 6. age and evolution of the buried drainage network the maximum possible age for the beginning of the shaping of the drainage network of the buried monferrato corresponds to the age of its emersion from the sea. the core of the monferrato hills, being surrounded by pliocene sediments of littoral facies, would have emerged already during the pliocene (sacco, 1889; carraro et al., 1980; dela pierre et al., 2003). the buried monferrato, made up of tertiary marine sediments, is surrounded by littoral sediments dated at the beginning of the gelasian (giraudi, 2016). it follows that during the gelesian the buried monferrato could already have emerged from the sea. other chronological data stem from the rit: the portion of the main divide buried below the oldest continental sediments (mis 22, started 0.87 ma ago) was shaped during the early pleistocene. in its southern part, the main divide lies buried beneath the sediments that form the late pleistocene and holocene terraces, is a very gently sloping ridge and, in theory, could have been formed in the whole period between the gelasian emersion and the late pleistocene-holocene. the differences in elevation between the various sections of the main divide, discussed before, allow it to be hypothesized that the whole divide was formed during the early pleistocene and was partially eroded during the erosional and depositional processes that led to the formation of the pleistocene and holocene terraces. 9. conclusions the morphology of the basal surface of the alluvial sediments that host the unconfined aquifer in the southern vercelli plain allows new hypotheses to be advanced as to the geological evolution of the area north and south of the lucedio and cavourrina faults. the main depressions are located just north and are parallel to the lucedio fault and crescentino and 101 the morphology of the base of the alluvial sediments of the vercelli plain (piedmont, nw italy): …. �� � � morano flexures, they overlap the area subsiding until the first half of the middle pleistocene, and are broken or end in correspondence with tectonic elements transverse to said structures. when the alpine rivers flowed north of the lucedio fault, the small streams, fed by the uplifting area south of the fault, flowed towards the rivers, carving small valleys. south of the lucedio fault, on the buried monferrato, there are ridges covered by alluvial sediments, and small valleys originated by erosion connected to the alpine rivers and local streams. the main buried ridge lies at the northern and western margins of the area uplifted by tectonics along the cavourrina fault and the fontanetto po deformation zone, and is almost parallel to these structures. this ridge can be interpreted as a divide between catchment basins of short streams, that drained to the se, and the po basin. in the area between the lucedio fault and the hills lie other small buried ridges, corresponding to minor divides between the basins of local streams. the buried valleys and ridges were carved mainly during the period between the gelasian and the late early pleistocene, but in part of the area south of the trino isolated hill they were eroded until the late pleistocene and the holocene. the direction of the small buried valleys was similar to that of the present-day valleys in the monferrato hills, to the course of the po and to the belt of its most recent terraces. in addition, changes in the direction of the valleys occur in correspondence with tectonic elements transverse to the lucedio and cavourrina faults and the crescentino and morano flexures. the direct or 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(2008) il pliocene del sottosuolo di casale monferrato (piemonte, italia nordoccidentale): dati preliminari. atti mus. civ. stor. nat. trieste, suppl. 53, 233-264. 103 ms. received: february 28, 2017 final text received: october 4, 2017 the morphology of the base of the alluvial sediments of the vercelli plain (piedmont, nw italy): …. �� � � 104 amq63 salari kotsakis 2.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 30 (2), 2017, 125-136 late pleistocene bat assemblage with eptesicus nilssonii from grotta del fossellone (southern latium, central italy) leonardo salari 1, tassos kotsakis 2 1 c/o dipartimento scienze della terra, “sapienza” università di roma, italy 2 dipartimento di scienze, università “roma tre”, roma, italy corresponding author: l. salari <leonardosalari@virgilio.it> abstract: the study of the late pleistocene fossil assemblage of bats from the grotta del fossellone (circeo promontory, central italy) has revealed the presence of six species, rhinolophus ferrumequinum, rhinolophus euryale, myotis (myotis) blythii, myotis (leuconoë) capaccinii, eptesicus nilssonii and miniopterus schreibersii. in the late mousterian and aurignacian levels of the cave (mis 3), only m. blythii is observed, indicating open spaces around the cave. in the gravettian levels (mis 2) all the species mentioned are present, which indicates a mosaic environment with forested areas alternating with open spaces (grassland or steppe) and wetlands. particularly interesting is the presence of e. nilssonii, the only species of the assemblage currently distributed in central and northern europe. the italian peninsula, and particularly its central and southern parts, have evidently acted as a glacial refugium during the last glacial maximum for the boreal species that later, in the lateglacial and holocene, expanded its distribution to the northern regions recolonizing the lands liberated from the glacial coverage. keyword: chiroptera, circeo promontory (central italy), glacial refugia, palaeoecology, palaeobiogeography 1. introduction grotta del fossellone (san felice circeo, latium, italy) opens in the limestone of the middle lias (sgi, 1960) front in the circeo promontory, within the circeo national park. the stratigraphic successions present at fossellone and in 38 further caves form an integrated group of evidences on the prehistory in this area. today, several of these caves faces the sea, a few meters above sea level, but in the colder periods of late pleistocene the coast line was distant, due to the lowering of the sea level up to -120 m (alessio et al., 1994; benjamin et al., 2017), and the caves dominated a coastal plain (blanc & segre, 1953). many of the caves have yielded notable sedimentary deposits with pleistocene fauna, lithic industries and/or human fossils (e.g., grotta barbara, grotta breuil, grotta delle capre, grotta del fossellone, grotta guattari, riparo blanc; fig. 1) (vitagliano & bruno, 2012). archaeological and palaeontological remains from grotta del fossellone were discovered in 1936 by alberto carlo blanc (1906-1960), during his first excavation campaign in the grotta delle capre, located 200 m away (blanc, 1937). subsequently, there were two main phases of explorations in the cave. during the first phase, from 1937 to 1940, a few test excavations were carried out in a small group of minor caves that open in the internal main hall. in particular, some prehistoric layers in the main slope were identified, where several explorative trenches were opened. during the second phase, from 1947 to 1953, systematic excavations of the deposit in the central slope were carried out, where the most complete stratigraphic sequence was present, forming 51 layers through to the “tyrrhenian beach”, with a thickness of about 14 m (blanc & segre, 1953; alhaique et al., 1996). in 1953-54 some human bone fragments, including a mandible of a baby, ascribed to homo neanderthalensis were discovered (mallegni, 1992). in 1989, systematic studies of the archaeological and palaeontological collections started (vitagliano & piperno, 1991; alhaique et al., 1996, 1998; alhaique & tagliacozzo, 2000). the bat fossils were given to us for the study by the late professor amilcare bietti (1937-2006), who was part of the archaeological team who made the last excavations in the cave. a preliminary list of the bat species was presented at the aiqua meeting in memory of alberto malatesta (1915-2007) in rome, 4-5 february 2010 (salari & kotsakis, 2011). in this paper the bat fossils collected in the grotta del fossellone are described and discussed. 2. stratigraphic notes grotta del fossellone (fig. 1) conserves pleistocene marine sediments (“tyrrhenian beach”) at the bottom of the sequence (blanc & segre, 1953; vitagliano & piperno, 1991; alhaique et al., 1996). the overlying continental sequence is composed of 51 layers in the central slope. the 10 layers at the bottom did not contain lithic industry. the other layers can be grouped into three units (blanc & segre, 1953; alhaique et al., 1996; vitagliano & bruno, 2012): 126 salari l., kotsakis t. fig. 1 grotta del fossellone (latium, italy): location of the site. 127 late pleistocene bat assemblage with eptesicus nilssonii from grotta del ..... levels 41-23 with lithic industries referred to the middle palaeolithic (mousterian); levels 21-17, separated from the mousterian levels by a layer of sterile red clay (level 22), with aurignacian industry; levels 16-1 with bone and lithic artefacts referred to gravettian. in the levels 27-23 a peculiar industry referred to the late and final mousterian was found (vitagliano & bruno, 2012). in these layers, the large mammal remains are scarce; the most frequent species is bos primigenius followed by cervus elaphus and less frequent wild horse, whereas wild boar, ibex and equus hydruntinus are rarer (alhaique et al., 1998; alhaique & tagliacozzo, 2000). the mammal assemblage in level 21, is considerably more abundant and it is dominated by e. hydruntinus followed by c. elaphus, whereas b. primigenius, wild horse, ibex, wild boar and roe deer are less frequent (alhaique et al., 1998; alhaique & tagliacozzo, 2000). bird bones, which are rare in levels 2723, are abundant in level 21, aurignacian, and mainly consist of perdix perdix, columba livia and pyrrhocorax graculus; from a climatic and environmental point of view, the occurrence of nyctea scandiaca and anser albifrons, cold and boreal birds, is particularly interesting (alhaique et al., 1998; alhaique & tagliacozzo, 2000). such as for bone and lithic artefacts, also the vertebrate remains are very scarce in levels 16-1, gravettian (alhaique et al., 1996; vitagliano & bruno, 2012). 3. materials and methods the material analysed is housed in the department of geological sciences of the “roma tre” university and it is numbered from lpvrt 00411 to lpvrt 00431. a few fossil remains come from level 23, mousterian, and level 21, aurignacian, and 46 specimens from levels 12, 9, 5, 4 and 1, gravettian (tab. 1). the bat remains were compared with osteological material, both fossil and recent, stored in the department of earth sciences of the university of rome “sapienza” and in the department of geological sciences of the “roma tre” university. moreover, we use morphological and morphometric data and dichotomous keys given by felten et al. (1973), sevilla garcía (1988), niethammer & krapp (2001), salari (2004) and lanza (2012). the analyses were performed with a stereoscopic microscope nikon smz-u in the department of sciences of the “roma tre” university; the pictures and the measurements were taken with a leika dfc290 system using the leica application suite software. for taxonomic determinations the analyzed material was chosen on the basis of its systematic importance (cranium, mandible and humerus). the minimum number of individuals (mni) was calculated using the most represented side (right or left) of maxillae, mandibles and humeri; this result was integrated with the analysis of the age and the dimensional characters of the other skeletal elements. in this work we follow simmons (2005), with the following exceptions. miniopteridae are considered as family, distinct from vespertilionidae, in agreement with mein & tupinier (1977), agnelli et al. (2006), millerbutterworth et al. (2007) and lanza (2012). we use the taxon myotis blythii instead of myotis oxygnathus, according to agnelli et al. (2006), furman et al. (2014) and juste & paunovi� (2016). this is also in agreement with most palaeontological works identifying remains of european largesized myotis, distinct from m. myotis, as m. blythii (not as m. oxygnathus or m. blythii oxygnathus). environmental reconstructions are based on studies on the ecology and biogeographical distribution of modern taxa (horá�ek et al., 2000; niethammer & krapp, 2001; agnelli et al., 2006; lanza, 2012). quaternary chronostratigraphy and geochronology according to gibbard et al. (2010). for italian continental biochronology we follow kotsakis et al. (2003). 4. taxonomy order chiroptera blumenbach, 1779 family rhinolophidae gray, 1825 genus rhinolophus lacépède, 1799 rhinolophus ferrumequinum (schreber, 1774) a mandible (lpvrt 00412), three humeri and two distal portions of humerus (lpvrt 00411, 00413-14) (figs. 2a-b; tab. 1) have the typical morphology of the genus rhinolophus. in the mandible, p4 is subquadrangular with pyramidal cusp; the molars are of nyctalodontic type, m1 and m2 have trigonid slightly longer than the talonid and the cingulum, very thin, more evident on the trigonid; m3 is relatively small and the cingulum is thin, especially on the talonid. in the distal epiphysis of humerus, epicondyle, trochlea, inner ridge tab. 1 grotta del fossellone, late pleistocene: number of identified specimens (nisp) and minimum number of individuals (mni) of species identified. l.: level. and lateral ridge are separated by grooves, less deep that dividing inner and lateral ridges; the styloid process is relatively long and thin, slightly dorsally inclined in lateral view (felten et al., 1973). these morphological features and the large size (tab. 2), enables a definite attribution to the big horseshoe bat. r. ferrumequinum is a species of mediterranean affinities and today’s range of distribution includes central europe, extending from southern england, and the mediterranean basin through asia to japan; in italy this species occurs in all regions (horá�ek et al., 2000; gaisler, 2001a; agnelli et al., 2006; lanza, 2012). the earliest fossil records of r. ferrumequinum come from some italian and spanish localities referred to the late early pleistocene (middle early biharian, late villafranchian; salari et al., 2013; galan et al., 2016a). indeed, many specimens of pliocene or early early pleistocene, assigned in the past to r. ferrumequinum 128 fig. 2 grotta del fossellone, late pleistocene: rhinolopus ferrumequinum: a) right mandible (lpvrt 00413), labial view, b) distal epiphysis of right humerus (lpvrt 00412); rhinolophus euryale: c) portion of cranium (lpvrt 00418), occlusal view, d) distal epiphysis of left humerus (lpvrt 00419); e) myotis blythii, distal epiphysis of left humerus (lpvrt 00421); f) myotis capaccinii, distal epiphysis of right humerus (lpvrt 00427); g) eptesicus nilssonii, distal epiphysis of left humerus (lpvrt 00428) (1 external, 2 internal, 3 dorsal views); h) miniopterus schreibersii, distal epiphysis of right humerus (lpvrt 00430). salari l., kotsakis t. or r. cf. ferrumequinum have been ascribed to other species of the group (topal, 1979; wo�oszyn, 1987). some pliocene or early early pleistocene remains recently assigned to the same taxa are reported in preliminary lists and their attribution must be confirmed. fossil remains of this species have been collected in several sites of middle pleistocene in central and southern europe and in north africa, and in many sites of late pleistocene from portugal and england to japan and south to maghreb and near east (capasso barbato & kotsakis, 1986; kotsakis, 1987, 1991; esu et al., 1990; lindenau, 2005; tata & kotsakis, 2005; argenti et al., 2008; tang & kotsakis, 2008; salari, 2009, 2010; salari & di canzio, 2009; salari et al., 2013, and references therein; horá�ek et al., 2013; galan et al., 2016b; sevilla, 2016; spena et al., 2017). rhinolophus euryale blasius, 1853 two incomplete crania (lpvrt 00418), five humeri and several distal portions of humerus (lpvrt 00415-17, 00419-20) (figs. 2c-d; tab. 1) belonging to the middle-sized species of genus rhinolophus. the preorbital bridge is strong (lanza, 2012), first and second upper molars have a distal concave edge and the labial cingulum is very prominent (sevilla garcía 1988), and the styloid process of distal humerus is long and thin, slightly dorsally inclined in lateral view (felten et al., 1973). these morphological features and the measurements (tab. 2) enables a sure attribution to mediterranean horseshoe bat. r. euryale is a species of strict mediterranean affinities, typically troglophilous; today’s range of distribution includes southern europe, south-western asia and north-western africa; in italy this species occurs throughout the territory with the probable exception of some northern regions (horá�ek et al., 2000; gaisler, 2001b; agnelli et al., 2006; lanza, 2012). bat fossils referred to rhinolophus ex gr. r. euryale are known in eastern europe since the early pliocene (late ruscinian), and in italy from late early pleistocene (middle early biharian, late villafranchian; salari et al., 2013). fossil remains of the mediterranean horseshoe bat come from several middle and late pleistocene localities of the mediterranean basin, poland and near east (kotsakis & petronio, 1980; kotsakis, 1991; lindenau, 2005; tata & kotsakis, 2005; salari & di canzio, 2009; salari, 2010; salari et al., 2013, and references therein; horá�ek et al., 2013; sevilla, 2016; 129 tab. 2 grotta del fossellone, late pleistocene: osteometric measurements (mm) and comparison with other sites. abbreviations: l. = maximum length; c-m3 = length of upper tooth-row between c and m3 (incl.); m1-m3 = length of upper molars; m3-m3 = rostral width between third upper molars (incl.); c-m3 = length of lower tooth-row between c and m3 (incl.); m1-m3 = length of lower molars; bd = distal breadth; n. = number of measurements; min = minimum; max = maximum; mea = mean; s.d. = standard deviation. *: m. myotis and m. blythii. grotta breuil unpublished data; caverna delle arene candide by salari (2010); mandible of extant r. ferrumequinum by gaisler (2001a); cranium of extant r. euryale by popov & ivanova (2002); distal breadth of humerus of all extant species by felten et al. (1973). late pleistocene bat assemblage with eptesicus nilssonii from grotta del ..... spena et al., 2017). family vespertilionidae gray, 1821 genus myotis kaup, 1829 subgenus myotis kaup, 1829 myotis (myotis) blythii (tomes, 1857) several distal portions of humerus (lpvrt 0042126) (fig. 2e; tab. 1) belonging to the great-sized species of genus myotis: the epicondyle is reduced, with trochlea, inner and outer ridges separated by grooves; the styloid process is strongly reduced but still present. with respect to the distinction between the largebodied myotis (excluding m. punicus for palaeobiogeographic reasons), the only certain morphological difference between the teeth of m. myotis and m. blythii occurs on the talonid of third lower molar, which is more reduced in m. myotis (see topál & tusnadi, 1963; sevilla garcía, 1988). concerning the humeri of identical morphology (felten et al., 1973), discrimination between the two species mainly relied on the distal epiphysis, ascribing only the larger ones and those of more robust aspect to m. myotis, with all remaining material being assigned to m. blythii. in our sample there are no particularly robust specimens and also the measurements (tab. 2) support the attribution to m. blythii. the lesser mouse-eared bat is a species of mediterranean affinities, thermophilous, the recent range of the species includes southern europe, the southern part of the central europe, east to china and mongolia; in italy it occurs in all regions with the possible exception of sardinia (horá�ek et al., 2000; topál & ruedi, 2001; agnelli et al., 2006; lanza, 2012). the earliest records of fossils referred to myotis cf. m. blythii come from some eastern europe sites referred to late pliocene (late ruscinian), and in italy from early early pleistocene (late villanyan, middle villafranchian; salari et al., 2013). fossil remains of this specie occur in several middle pleistocene localities and in many late pleistocene sites of southern and eastern europe and near east (capasso barbato & kotsakis, 1986; lindenau, 2005; tata & kotsakis, 2005; tang & kotsakis, 2008; salari, 2009, 2010; salari & di canzio, 2009; salari et al., 2013, and references therein; horá�ek et al., 2013; sevilla, 2016; spena et al., 2017). subgenus leuconoë boie,1830 myotis (leuconoë) capaccinii (bonaparte, 1837) a distal portion of a right humerus (lpvrt 00427) from level 1 (fig. 2f; tab. 1) is very similar in morphology (felten et al., 1973) and dimensions (tab. 2) to the humerus of living m. capaccinii: epicondyle with reduced trochlea, inner and outer ridges separated by grooves, and the styloid process is moderately developed. the long-fingered bat is a species of strict mediterranean affinities, typically troglophilous; the current range includes the mediterranean basin, southern europe, north-western africa, south-western asia to iran and uzbekistan; in italy this species occurs in all regions (horá�ek et al., 2000; spitzenberger & helversen, 2001; agnelli et al., 2006; lanza, 2012). the oldest fossils of the long-fingered bat are known in some mediterranean localities, including italy, since the late early pleistocene (middle early biharian, late villafranchian; salari et al. 2013). it is found in some middle and late pleistocene sites from central and southern italy and other circum-mediterranean localities, invariably represented by few remains, whereas in northern italy and in the remaining western palaearctic it is rarely reported (kotsakis & petronio, 1980; kotsakis, 1987; lindenau, 2005; tata & kotsakis, 2005; tang & kotsakis, 2008; salari, 2009; 2010; salari & di canzio, 2009; salari et al., 2013, and references therein; spena et al., 2017). genus eptesicus rafinesque, 1820 eptesicus nilssonii (keyserling and blasius, 1839) a distal portion of a left humerus (lpvrt 00428) from level 1 (figs. 2g1, 2g2, 2g3; tab. 1) is very similar in morphology (felten et al., 1973) and dimensions (tab. 2) to the humerus of living e. nilssonii: the epicondyle is reduced, inner and outer ridges separated by grooves, and the passage from the trochlea to the condyle is almost straight; the styloid process (a little broken) is moderately developed and the articular fossette is clear and wide. the northern bat is a species of boreal affinities and the only one, among all the bats in the world, which reproduces even beyond the arctic circle (as far as 70° 25’ n) (rydell et al., 1994; agnelli et al., 2006). its current range of distribution includes central and northern europe, extending from the northern balkans through the palearctic asia to sakhalin, korea and japan (gerel & rydell. 2001; agnelli et al.. 2006; lanza. 2012). currently, its southernmost limit of distribution in europe is the south-eastern alpine arch and the northern balkans, with isolated colonies in the rila mountains in bulgaria (hanák & horà�ek, 1986; gerel & rydell, 2001; lanza, 2012). the scarce records available for italy show that its presence is limited to some mountain resorts of the alpine arch (agnelli et al., 2006; lanza, 2012; patriarca & debernardi, 2014). e. nilssonii fossils are known since the early middle pleistocene in poland (wo�oszyn, 1987). during the late pleistocene and early holocene, this species settled in various sites of former soviet union, such as crimea, altai, siberia and far east (rydell, 1993; rossina, 2006; rosina, 2012; tiunov, 2016), central europe (horá�ek, 1995; popov, 2000; piksa & wo�oszyn, 2001; ochman, 2003; ochman & wo�oszyn, 2003; noël et al., 2008; pazonyi et al., 2014), and only at grotta del broion (veneto) in italy (pasa, 1953). family miniopteridae dobson, 1875 genus minioperus bonaparte, 1837 miniopterus schreibersii (kuhl, 1819) a humerus and two distal portions of humerus (lpvrt 00429-31) (fig. 2h; tab. 1) belong to the genus miniopterus: the medial epicondyle is relatively narrow, the trochlea is separated from the inner ridge by a not deep groove, while inner and lateral ridges are separated one from each other by a deep groove; the styloid process is long and narrow and is parallel to the axis of the humerus. these morphological features (felten et al., 1973) and the measurements (tab. 2) enables a definite attribution to m. schreibersii. schreiber’s bat is a species sub-cosmopolitan, but of strict mediterranean affinities, typically troglophilous; 130 salari l., kotsakis t. the current range comprises all populations living from southern europe and morocco to sub-saharan africa, madagascar and through southern asia to oceania; in italy this species occurs throughout to the whole country (horá�ek et al., 2000; agnelli et al., 2006; lanza, 2012). m. schreibersii is known since the early early pleistocene (late villanyan, middle villafranchian) in various localities of central europe, and in italy from late early pleistocene (middle early biharian, late villafranchian; salari et al., 2013). schreiber’s bat disappeared from central europe during the glacial phases of middle and late pleistocene but was present in the mediterranean basin and expanded its area of distribution further north during the interglacial phases (kotsakis & petronio, 1980; kotsakis, 1987, 1991; lindenau, 2005; tata & kotsakis, 2005; tang & kotsakis, 2008; salari, 2009, 2010; salari & di canzio, 2009; salari et al., 2013, and references therein; horá�ek et al., 2013; galan et al., 2016b; sevilla, 2016; spena et al., 2017). 5. discussion all the six species identified at grotta del fossellone (tab. 1) are still part of the extant italian bat fauna (agnelli et al., 2006; lanza, 2012). among these, rhinolophus ferrumequinum, rhinolophus euryale, myotis blythii, myotis capaccinii and miniopterus schreibersii today occur in latium (crucitti, 2011; capizzi et al., 2012) and also within the circeo national park territory, except probably for m. blythii (see mastrobuoni & zerunian, 2003; mastrobuoni, 2009a, 2009b), whereas eptesicus nilssonii occurs only in a few localities of alpine arch (agnelli et al., 2006; lanza, 2012; patriarca & debernardi, 2014). except for e. nilssonii, all the fossils belong to troglophilous species (tab. 3), and ascertained traces of digestion on the bone surfaces were not found (except for two remains of r. euryale and r. ferrumequinum). therefore, it is very likely that the bat remains consisted mainly of the natural accumulation of animals that lived and died in the cave (sevilla garcía, 1988; kowalski, 1995; salari & silvestri, 2015). bats have a foraging range of several kilometres from their roosts (niethammer & krapp, 2001; agnelli et al., 2006; lanza, 2012). therefore, by analysing the present distribution areas and foraging environments of the species identified (tab. 3), the study of the fossil assemblage provides interesting information on the surroundings of the cave at the time of their deposition. for refined quantitative analyses, significantly numerous samples are required, taking into account that some species form large colonies (monospecific or mixed), even of thousands of individuals, others form smaller colonies, from a few individuals to several hundred or have more solitary behaviours (tab. 3). however, despite the limited numerical significance of our sample, it can still provide useful environmental information. in the levels 23, mousterian, and 21, aurignacian, only few remains of m. blythii were found, and one can only admit that probably in the surrounding of cave were also open spaces, as confirmed by the occurrence of equids (alhaique et al., 1998; alhaique & tagliacozzo, 2000). instead, in the mousterian layers of the grotta breuil, also in the circeo promontory, a rich fossil bat assemblage was found (kotsakis, 1991; salari & di canzio, 2009; salari & kotsakis, 2011). the ecological features of the species found in this cave are compatibles with the environmental reconstruction outlined by alhaique et al. (1998) and alhaique & tagliacozzo (2000) for the surroundings of grotta del fossellone. also in the mousterian of nearby grotta barbara were found several bat fossils and even the ecological features of the species found in this cave suggest a variety tab. 3 synthetic notes on foraging environment and roosting habits in italy and zoogeographical pattern for the species considered. data from horá�ek et al. (2000), agnelli et al. (2006), salari & di canzio (2009), lanza (2012); m a.s.l.: meters above sea level; s.l.: sensu lato; s.s.: sensu stricto. 131 late pleistocene bat assemblage with eptesicus nilssonii from grotta del ..... of environments in the circeo promontory during this phase of late pleistocene (salari & kotsakis, 2011). the six species found in the gravettian layers of grotta del fossellone foraging in various environments (tab. 3), and its ecological features allow us to outline a composite landscape with extensive woodlands interspersed with open spaces (steppe, grasslands and scrubland), rocky areas and marginal wetland. levels 12-5 yielded few remains and the species more frequent is m. blythii, while level 1 makes more numerous bat fossils, m. blythii disappear and the species dominant is r. euryale (tab. 1). despite the limited amount of fossils that precludes any definitive conclusion, it can be assumed that the environment surrounding the cave has evolved from more open towards greater forest cover. the occurrence of e. nilssonii, a non troglophilous species, cold and boreal bat, far to the south of the limit of its current distribution, suggests a colder climate than the present. according to alhaique et al. (1998) and alhaique & tagliacozzo (2000), the bird and mammal assemblages from level 21 indicate a climate colder than that documented in the mousterian layers. the bat assemblage seems to suggest that during the gravettian the climate further evolved towards the cold. the levels 27-23, mousterian, can be referred to temperate oscillations of marine isotope stage (mis) 3, the aurignacian layers to the final mis 3 or the beginning of mis 2 (salari & kotsakis, 2011), and the gravettian layers can be referred to mis 2, around to the last glacial maximum (lgm). indeed, according to some authors (e.g., mussi, 2002; antonioli & vai, 2004; sala, 2005) the gravettian industry is well documented in italy during this coldest period of the late pleistocene. in the lgm, iberian and italian peninsulas and the balkans played the role of main glacial refugia for many temperate or warm animal and plant species, which repopulated the rest of europe during the lateglacial and holocene (bilton et al., 1998; stewart & lister, 2001; sommer & nadachowski, 2006; gavin et al., 2014). as for european bats, fahlke (2009) reported that these have deserted the area north to the alps in the lgm, and that it was only in the first stages of the lateglacial, during the bølling-allerød temperate oscillations, that some species (eptesicus serotinus followed by plecotus auritus and barbastella barbastellus) returned to the area. in effect, few other bats, including e. nilssonii, nyctalus noctula and a few species of the genera myotis and pipistrellus are reported in the lateglacial sequences of central-northern europe (horá�ek, 1995; ochman, 2003; horá�ek & jahelková, 2005). moreover, according to fladerer (2000), in the southeastern side of the alps in the lgm the only presence of p. auritus is documented, then during the lateglacial the area would be populated by vespertilio murinus, followed by e. serotinus, m. myotis, myotis bechsteinii, myotis nattereri and b. barbastellus. in the cold periods of late pleistocene, centralsouthern italy and liguria hosted many species which are now largely distributed in central and northern europe (e.g., rhinolophus hipposideros, myotis dasycneme, m. myotis, m. bechsteinii, myotis mystacinus, p. auritus, n. noctula and b. barbastellus) (argenti et al., 2008; salari, 2010; salari & kotsakis, 2011; bogdanowicz et al., 2015), and that have returned to these lands, but even in some regions south of the alps (e.g., canton ticino, switzerland), only in the holocene (horá�ek, 1995, 2007; horá�ek & jahelková, 2005; blant et al., 2008; ruedi et al., 2008; fahlke, 2009; hutterer et al., 2012). thus, the occurrence of e. nilssonii in the lgm at grotta del fossellone show that circeo promontory played a role of glacial refugium in the late pleistocene for this boreal species currently distributed in central and northern europe. 6. conclusion six species of bats divided into three families (rhinolophidae, vespertilionidae and miniopteridae) and four genera (rhinolophus, myotis, eptesicus and miniopterus) have been discovered in the fossil assemblage from grotta del fossellone. all the species identified are still part of the extant italian bat fauna and today also occur in latium, except for eptesicus nilssonii that is now distributed in central-northern europe. the fossil bat assemblage examined is probably an autochthonous thanatocoenosis. the bat remains do not show major morphological or morphometric differences from other late pleistocene and extant populations of the same species. the ecological needs of the species of bats present at grotta del fosselone allow to outline for the gravettian period a composite environment with wooded areas interrupted by open spaces (grassland or steppe), rocky areas and wetlands. the occurrence in the latest gravettian layer of e. nilssonii, far to the south of the limit of its current distribution, suggests a colder climate than the mousterian and aurignacian layers and the present. probably the gravettian layers were deposed in the lgm. grotta del fossellone represents the southernmost limit of e. nilssonii in europe, even considering its distribution in the pleistocene. the occurrence of this species in the lgm at grotta del fossellone, as well as of m. dasycneme in the lateglacial of grotta di cittareale (argenti et al., 2008; salari & kotsakis, 2011), show that during the coldest stages of the late pleistocene the coastal regions and the apennine of latium must have played an important role of glacial refugia for these boreal species which are now distributed in centralnorthern europe. acknowledgements we want to thank maria rita palombo and lutz maul for their useful comments to our manuscript. references alessio m., allegri l., antonioli f., belluomini g., improta s., manfra l., preite martinez m. 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(1987) pliocene and pleistocene bats of poland. acta palaeontologica polonica, 32, 207 -325. 136 ms. received: july 3, 2017 final text received: november 20, 2017 salari l., kotsakis t. microsoft word 00_indice_lm04.docx il quaternario it issn 039-3356 italian journal of quaternary sciences 24 (1), 2011 75-92 a revision of the “northern guest” ostracoda (crustacea) occurrence in the quaternary of the mediterranean area costanza faranda1 & elsa gliozzi1,2 1dipartimento di scienze geologiche, università degli studi roma tre, roma 2 istituto di geologia ambientale e geoingegneria, cnr, roma corresponding author: e. gliozzi <gliozzi@uniroma3.it> abstract: faranda c. & gliozzi e., a revision of the “northern guest” ostracoda (crustacea) occurrence in the quaternary of the mediterranean area. in this paper the revision of the “northern guest” ostracods widespread in the mediterranean area during quaternary time is proposed. the abundant literature on this topic lists up to twenty-three species. they have been critically revised and a list of only twelve true “northern guests” is provided: acanthocythereis dunelmensis (norman, 1865), bythocythere turgida sars, 1866, bythocythere zetlandica athersuch, horne & whittaker, 1983, cythere lutea müller 1785, cytheropteron depressum (brady & norman, 1889), cytheropteron punctatum brady, 1868, cytheropteron testudo sars, 1870, hemicythere villosa (sars, 1865), paradoxostoma abbreviatum sars, 1866, paradoxostoma ensiforme brady, 1866, paradoxostoma tenuissimum (norman, 1869) and semicytherura angulata (brady, 1868). these species are generally rare, being found with very few specimens and mainly in one locality. only cytheropteron testudo and cytheropteron punctatum have been reported with a wide geographical distribution in italy and in the aegean sea. the twelve “northern guest” ostracods entered the mediterranean at different times, being more abundant in the early pleistocene sicilian substage. only one study on the last glacial maximum marine ostracods has been carried out recording the presence of c. testudo. the record of loose valves of “cold” ostracod species (c. testudo, p. tenuissimum and b. turgida) among the living mediterranean assemblages suggests that they could have migrated into the mediterranean even during late pleistocene time. in this paper, a critical revision of the existing literature about “northern guest” ostracods is presented, together with their stratigraphical and geographical distribution in the mediterranean, and three new “northern guest” ostracod species are added. riassunto. faranda c. & gliozzi e., revisione della presenza dell’ospite freddo ostracoda (crustacea) nel quaternario dell’area mediterranea. in questo lavoro viene proposta la revisione critica degli ostracodi “ospiti nordici” che si diffusero nel mediterraneo durante le fasi climatiche fredde che caratterizzarono il quaternario. l’abbondante, seppure frammentaria letteratura esistente su questo argomento, elenca ventitrè specie di ospiti nordici; in seguito alla presente revisione questo numero è ridotto a sole dodici specie di ostracodi che possono essere considerati veri “ospiti nordici”: acanthocythereis dunelmensis (norman, 1865), bythocythere turgida sars, 1866, bythocythere zetlandica athersuch, horne & whittaker, 1983, cythere lutea müller 1785, cytheropteron depressum (brady & norman, 1889), cytheropteron punctatum brady, 1868, cytheropteron testudo sars, 1870, hemicythere villosa (sars, 1865), paradoxostoma abbreviatum sars, 1866, paradoxostoma ensiforme brady, 1866, paradoxostoma tenuissimum (norman, 1869) e semicytherura angulata (brady, 1868). queste specie sono generalmente rare sia nelle associazioni, dove spesso sono rappresentate da pochissime valve, sia come presenza nell’area mediterranea, essendo prevalentemente segnalate in una sola località. solo cytheropteron testudo e cytheropteron punctatum sembrano avere una distribuzione geografica piuttosto ampia, sia nel mediterraneo centrale (italia) sia in quello orientale (mare egeo). le dodici specie di ostracodi “ospiti nordici” migrarono nel mediterraneo in tempi quaternari diversi e risultano più abbondanti in corrispondenza del sottopiano siciliano. l’unico studio sulle ostracofaune marine dell’ultimo pleniglaciale ha permesso di registrare la presenza di c. testudo anche nella parte alta del quaternario. e’ possibile che a questa specie ne possano venire aggiunte almeno altre due (p. tenuissimum and b. turgida) le cui valve isolate, prive di parti molli, sono state rinvenute nei fondali del mediterraneo insieme ad ostracofaune viventi. keywords: marine ostracods, northern guests, mediterranean, quaternary, stratigraphic distribution. parole-chiave: ostracodi marini. ospiti nordici, mediterraneo, quaternario, distribuzione stratigrafica. 1. introduction at the 18th international geological congress (london, 1948), the lower boundary of the quaternary era (tertiary/quaternary boundary) was established “at the horizon of the first indication of the climatic deterioration in the italian neogene succession” (pillans & naish, 2004, p. 2272). consistent with this recommendation, the basal part of the quaternary included the “calabrian”, a marine mediterranean stage defined by gignoux (1910) at s. maria di catanzaro (calabria, southern italy) and originally assigned by this author to the pliocene. in fact from the s. maria di catanzaro outcrop some “northern guest” molluscs such as arctica islandica were collected, and their presence indicated a climatic cooling, as pointed out by suess (1883-1909). several studies followed, in which numerous “northern guest” molluscs, foraminifers and ostracods were listed, and their appearance in the mediterranean area occurred in different pleistocene times (ruggieri, 1975, 1977, c. faranda & e. gliozzi 76 1980; ruggieri & sprovieri, 1977; malatesta & zarlenga, 1986). recently, through the stable isotope analyses of marine foraminifers, a first global cooling was detected in correspondence to the marine isotopic stage 100 (raymo et al., 1989), which falls about 60 ka after the middle/late pliocene boundary (piacenzian/gelasian gssp at monte s. nicola section (sicily) (rio et al., 1998). this discovery led the scientific community to discuss the possibility to move the pliocene/quaternary boundary down to the base of the gelasian. after around twenty years of heateded debates (cita & castradori, 1994 with references; vai, 1996 with references; suc et al., 1997 with references), in 2007 the inqua and ics stratigraphic commissions have jointly proposed a new stratigraphic assessment of pliocene and quaternary (ogg, 2007) (fig. 1), ratified by the ics commission during may 2009 (cita, 2009; mascarelli, 2009). in this new global stratigraphic scheme, the neogene/quaternary boundary corresponds to the base of the gelasian stage (2.588 ma), which represents the first stage of the quaternary system and also the first stage of the pleistocene series (gibbard et al., 2010). at present, the quaternary system includes the ratified or proposed standard stages gelasian, calabrian, ionian and tarantian (rio et al., 1998; cita et al., 2006). thus, in this paper, also the “cold” ostracods that entered the mediterranean during the gelasian are considered quaternary “northern guests”, since, as re-defined by ruggieri (1977), a species can be considered a true mediterranean “northern guest” if it is at present living outside the mediterranean, at more northern latitudes, and entered the mediterranean area during the “cold” global climatic oscillations. moreover, we consider stratigraphically useful to maintain the subdivision of the calabrian stage into the santernian, emilian and sicilian mediterranean regional substages, as defined by ruggieri et al. (1984) for the mediterranean. 2. the “northern guest” ostracods in the literature: a critical revision the first author who signalled the presence of “cold” ostracods in the mediterranean was ruggieri (1952a) who recovered a fragment of cytheropteron testudo sars 1870 from the lower pleistocene grey sands of imola (northern italy). since then, ruggieri and other authors have discussed the presence of “northern guest” ostracods in several papers (ruggieri, 1956, 1959, 1971, 1973, 1974, 1975, 1976, 1977, 1980; ruggieri et al., 1976, 1977; ruggieri & sprovieri, 1977; sissingh, 1976; faranda & gliozzi, 2008), giving a rather long list of species: actinocythereis dunelmensis (norman, 1865) argilloecia cylindrica sars, 1866 bythocythere dromedaria sars, 1866 bythocythere insignis sars, 1869 bythocythere zetlandica athersuch, horne & whittaker, 1983 cluthia keiji neale, 1975 cythere lutea müller, 1785 cytheropteron depressum (brady & norman, 1889) cytheropteron latissimum (norman, 1865) = cytherop teron sp. ex gr. c. latissimum (norman, 1865) cytheropteron punctatum brady, 1868 cytheropteron testudo sars, 1869 hemicythere villosa (sars, 1866) leptocythere macallana (brady & robertson, 1869) macrocypris minna (baird, 1850) muellerina problematica (seguenza, 1884) muellerina sp. nov. cf. m. abissicola (sars, 1866); nereina (?) sp. ind. paradoxoxtoma abbreviatum sars, 1866 paradoxostoma ensiforme brady, 1868 semicytherura angulata (brady, 1868) semicytherura producta (brady, 1868) thaerocythere (?) sp. xiphichilus tenuissimus (norman, 1869) the validity as “northern guests” of some of these species was discussed in several papers by ruggieri and by other authors. in particular: argilloecia cylindrica sars, 1866 some valves recovered by colalongo (1966) at le castella (calabria, southern italy) and referred to this northern species (colalongo, 1966; ruggieri, 1971) were subsequently revised by greco et al. (1974 p. 174) and assigned to the species zabythocypris antemacella (maddocks); the specimens from le castella and monasterace [calabria, southern italy of greco et al. (1974)] have been recently included by aiello, barra & bonaduce (1996a) within their new species anchistrocheles interrupta. bythocythere dromedaria sars, 1866 ruggieri (1956) assigned to this species some juvenile valves from the ?santernian of talignano (parma, northern italy) and from the emilian of sciacca (sicily, near bar maddalena); afterwards, ruggieri (1973) reported immature valves from pliocene deposits (no localities are specified), thus, this author cancelled the species from its “northern guest” list. we have seen the ruggieri ostracod collection (roc.) stored at the paleontological museum “g.g. gemmellaro” (palermo university), but, at present, it has not been possible to check the pliocene specimens since they are not in the collection, whereas the specimen from talignano (roc n° 1651) is not a bythocythere but a juvenile of pseudocythere (fig. 2). bythocythere insignis sars, 1869 according to ruggieri (1973), the valves recovered at ficarazzi (ruggieri, 1956) and acqua dei corsari (palermo, sicily) and referred to this species must be ascribed to monoceratina mediterranea sissingh, 1972. macrocypris minna (baird, 1850) ruggieri (1973) doubtfully included this species in its list of “northern guests” because it was recorded only by seguenza (1883-86) and never recovered again. indeed, seguenza dubitatively referred an anterior fragment of a valve of macrocyprididae to macrocypris minna? and he did not provide any illustration. muellerina sp. nov. cf. m. abyssicola (sars, 1866) ruggieri (1973) recognised a new species of muellerina, from the emilian of foce del verdura (sciacca, sicily) and compared it with the northern species m. abyssicola (sars 1866) suggesting that the italian specimens could be either a subspecies of this taxon or a new species phylogenetically linked to it. afterwards, ruggieri (1975) referred muellerina sp. nov. cf. m. abyssicola to the fossil species muellerina problematica a revision of the “northern guest” ostracoda (crustacea) occurrence in the quaternary of the … 77 fig. 1 magnetostratigraphy, chronostratigraphy, biostratigraphy and oxygen isotope stratigraphy of the quaternary system (isotopic scale from lourens et al., 2004). magnetostratigrafia, cronostratigrafia, biostratigrafia e stratigrafia isotopica del sistema quaternario (scala isotopica da lourens et al., 2004). (seguenza, 1884) but, because of its affinity with m. abyssicola, he continued to consider this species as a northern guest (ruggieri, 1977, 1980, 1991; ruggieri & sprovieri, 1977) even if it is a fossil species. yassini (1979) recovered muellerina latimarginata (speyer, 1863) (=m. problematica) in the piacenzian-gelasian of algeria and, more recently ciampo (1992) recovered m. problematica at s. todaro (calabria, southern italy) in the zanclean (mpl 3), thus, this species can no longer be considered a quaternary “northern guest”. leptocythere macallana (brady & robertson, 1869) ruggieri et al. (1976, 1977) included this spe c. faranda & e. gliozzi 78 fig. 2 pseudocythere sp.: broken left juvenile valve (transmitted light). this specimen is stored in the roc slide n° 1651 under the name bythocythere dromedaria talignano (parma). bar corresponds to 0.1 mm. pseudocythere sp.: valva sinistra giovanile rotta in luce trasmessa. l’esemplare è conservato nella collezione ostracodi ruggieri teca n° 1651 con il nome bythocythere dromedaria talignano (parma). la barra corrisponde a 0.1 mm. cies among the ostracod “northern guests” because it had been recovered from several calabrian deposits of calabria and sicily (ruggieri, 1952b; ruggieri et al., 1976, 1977). athersuch et al. (1989) consider the mediterranean species leptocythere levis (müller, 1894) a younger synonym of this species. ruggieri & d’arpa (1993) did not agree with this position. however, they recovered l. macallana in the piacenzian of altavilla (sicily), thus the species cannot be included any more among the quaternary “northern guests”. cytheropteron latissimum (norman, 1865) = cytheropteron sp. ex gr. c. latissimum (norman, 1865) ruggieri (1975) records the presence of c. latissimum in the sicilian deposit of acqua dei corsari (ficarazzi, sicily). in his paper of 1977, ruggieri changed the attribution of this species, considering it a species of cytheropteron different although similar to c. latissimum. unfortunately, ruggieri did not clearly characterise it taxonomically, nor did he illustrate it. the slide of this species within the ruggieri ostracod collection is empty. cluthia keiji neale, 1975 this species occurs for the first time in the mediterranean area in the calabrian (santernian). ruggieri (1977) and ruggieri & sprovieri (1977) included c. keiji within the “cold species” which migrated into the mediterranean in correspondence with the onset of the first pleistocene cooling episode. ruggieri (1977) himself stated that it could not be considered a true “northern guest” since the species adapted to the mediterranean climatic conditions and it is still living in this region. cluthia keiji was recovered by carbonnel & ballesio (1982) in the piacenzian deposits of the rhône valley, thus it cannot be considered as either a quaternary “northern guest” nor a “émigrés du nord attardés” sensu gignoux (1913) (ruggieri, 1977). thaerocythere (?) sp. (in ruggieri, 1977) = nereina (?) sp. indet. (in ruggieri, 1980) we agree with ruggieri (1977) that the specimens collected and illustrated from the sicilian of the valle del belice (sicily) cannot be referred with certainty to the genus thaerocythere hazel, 1967. the shape of the posterior border and the ornamentation of the valve illustrated by ruggieri (1977) point to the genus grinioneis liebau, 1975. in any case, the sicilian valves are completely different from the recent arctic species thaerocythere crenulata (sars, 1866). the same specimens cannot be referred to the arctic genus nereina mandelstam, 1957 because the hinge is different, smooth in nereina but with a crenulated bar in the valle del belice specimens. thus, the doubtful attribution of these valves as a possible “northern guest” cannot be accepted. following our revision, the specimen hosted as thaerocythere (?), valle del belice, in the ruggieri ostracod collection at palermo (n° 2766) is referable to muellerina problematica, and is not the specimen illustrated by ruggieri (1977). probably, a dislocation of the stored valve occurred and the original specimen identified as thaerocythere(?) must be considered lost. semicytherura producta (brady, 1868) ruggieri (1976) reports this species from the calabrian of chirco, ciantrato (marsala, sicily) and ficarazzi (sicily). during the revision of the ruggieri’s collection these specimens have not been found. in the collection there is one never published broken valve from via del fante (palermo, sicily), (g.o.c. n° 2593c), from which it is impossible to confirm the identification. thus, for the moment, the presence of s. producta in the mediterranean during quaternary is dubitative. in conclusion, only the following 11 species, reported with the updated nomenclature, can be considered true “northern guest” ostracods: acanthocythereis dunelmensis (norman, 1865) bythocythere zetlandica athersuch, horne & whittaker, 1983 cythere lutea müller, 1785 cytheropteron depressum (brady & norman, 1889) cytheropteron punctatum brady, 1868 cytheropteron testudo sars, 1869 hemicythere villosa (sars, 1866) paradoxostoma abbreviatum sars, 1866 paradoxostoma ensiforme brady, 1868 paradoxostoma tenuissimum (norman, 1869) semicytherura angulata (brady, 1868) to this list one more species should be added, not noted by ruggieri as a quaternary “northern guest” since he recovered it from the gelasian of castellarquato (piacenza) (ruggieri, 1976): bythocythere turgida (sars, 1866). 3. stratigraphic and geographic distribution of the quaternary “northern guest” ostracods in the mediterranean area acanthocythereis dunelmensis (norman, 1865) (fig. 3) 1865 cythereis dunelmensis sp. n. norman, pp. 22, pl. 7, figs. 1-4. 1967 acanthocythereis (?) dunelmensis (norman) hazel, p. 34. 1969 trachyleberis dunelmensis (norman) nov. comb. yassini, p. 49. 1977 actinocythereis dunelmensis (norman) nov. comb. ruggieri, p. 83, fig. 1. 1989 acanthocythereis dunelmensis (norman) nov. comb. athersuch et al., pp.132-134, fig. 52; pl. 3, fig. 10. a revision of the “northern guest” ostracoda (crustacea) occurrence in the quaternary of the … 79 fig. 3 acanthocythereis dunelmensis: (a) right valve under transmitted light, (b) left valve under sem from catarinicchia (belice valley, sicily), sicilian age; (roc slide n° 2760); (c) present geographical distribution (dark grey line) and early pleistocene distribution in the mediterranean area (black dot). bar corresponds to 0.1 mm. acanthocythereis dunelmensis: (a) valva destra in luce trasmessa, (b) valva sinistra in scansione elettronica, provenienti dalla località catarinicchia locality (valle del belice, sicilia), età siciliano; (collezione ostracodi ruggieri teca n° 2760); (c) distribuzione geografica attuale (linea grigio scura) e distribuzione nel mediterraneo nel pleistocene inferiore (punti neri). la barra corrisponde a 0.1 mm. recent distribution: s. baltic sea, öres, bohuslän, n. norway, iceland and arctic seas, shetlands, ne british isles, east greenland (athersuch et al., 1989; malz, 1989; hansson, 1998; frenzel et al., 2010); hornsund (south spitsbergen) (mackiewicz, 2006); laptev sea (n. russia) (stepanova et al., 2003, 2007, 2010). ostracod bioprovince: celtic arctic (fig. 4) ecology: it inhabits the marine inner outer shelf environment (50-100 m), in polyhaline-euhaline conditions and water temperatures that range from -2 to 13 (19)°c (wilkinson, 2005; stepanova et al., 2007, 2010; frenzel et al., 2010). fossil distribution in the mediterranean: calabrian (sicilian): belice, (sicily) (ruggieri, 1977, 1980). bythocythere turgida sars, 1866 (fig. 5) 1866 bythocythere turgida sp. nov. sars, p. 84, pl. 107, figs. 1-12. bythocythere turgida is a problematic species. the original drawings by sars (1866, 1928) are the only available illustrations of this species. athersuch et al. (1983), revising the bythocythere species from the british coasts, split this species into three different taxa: b. turgida, at present distributed only on the norway coasts, b. robinsoni athersuch, horne & whittaker, 1983, and b. bradleyi athersuch, horne & whittaker, 1983, living only in the british waters. unfortunately these authors did not illustrate b. turgida s.s. malz & jellinek (1984) agree with athersuch et al. (1983) and discuss the possible attribution of their specimen to b. turgida. in the present paper we consider the specimen illustrated by malz & jellinek (1984) from the calabrian (emilian) of peloponnesus (greece) as males of fig. 4 eastern atlantic ostracod bioprovinces (redrawn from frenzel et al., 2010). bioprovince ad ostracodi dell’atlantico orientale (ridisegnata da frenzel et al., 2010). c. faranda & e. gliozzi 80 fig. 5 bythocythere turgida: (a) left valve from breman, 1976; (b) present geographical distribution (dark grey line), early pleistocene distribution in the mediterranean area (black dot), last glacial maximun distribution in the mediterranean (white circle). bar corresponds to 0.1 mm. bythocythere turgida: (a) valva sinistra da breman, 1976; (b) distribuzione geografica attuale (linea grigio scura), distribuzione nel mediterraneo durante il pleistocene inferiore (punti neri) e durante il pleniglaciale (cerchi bianchi). la barra corrisponde a 0.1 mm. b. puncticulata ruggieri, 1976. even the specimen from the zanclean of bou ismail (algeria) illustrated as bythocythere turgida by yassini (1979) could be a female of the same species. the bythocythere turgida specimen from partanna (sicily, early calabrian) recovered in the roc slide n° 2526 is not referable to this species but to a juvenile male of b. puncticulata ruggieri, 1976 (fig. 6). the inclusion of b. turgida within the list of the living mediterranean species (aiello et al., 1995) is due to the recovery of some loose valves from the adriatic and tyrrhenian seas (bonaduce et al., 1976, 1983; breman, 1976; arbulla et al., 2001, 2004). according to ruggieri (1976) the specimens collected by breman in the adriatic sea must be considered as subfossil and referable to the last pleniglacial maximum migration. we suppose that also the bonaduce et al. (1976) specimens from the same sea were subfossil. arbulla et al. (2001, 2004) recover the few juvenile valves of b. turgida from la maddalena (sardinia) in a sample at 2-7 m of depth. such shallow depth lead us to infer that these specimens too are subfossil. in conclusion, we consider bythocythere turgida as a true “northern guest”. recent distribution: koster channel, oslofjord, s and w norway, spitzbergen (athersuch et al., 1983; malz & jellinek, 1994; hansson, 1998). ostracod bioprovince: norwegian arctic (fig. 4) ecology: according to elofson (1941) it is a polyhalineeuhaline species that inhabits shallow to rather deep waters (20-140 m) fossil distribution in the mediterranean: gelasian: castellarquato (piacenza, northern italy) (ruggieri, 1976) calabrian (emilian): cinisi (palermo, sicily) (ruggieri, 1976). tarantian (last pleniglacial): adriatic sea (bonaduce et al., 1976; breman, 1976) tyrrenian sea (maddalena island) (arbulla et al., 2001; 2004) western mediterranean basin (near algerian coast) (bonaduce et al., 1983) bythocythere zetlandica athersuch, horne & whittaker, 1983 (fig. 7) 1983 bythocythere zetlandica sp. nov. athersuch, horne & whittaker, p. 73, figs. 5c, 41-n; pl. 2, figs. 5-8. in the roc slide n° 856 a broken juvenile specimen is stored labelled bythocythere cf. b. zetlandica collected from the gelasian capocolle clays (forlì, northern italy) (fig. 8). we have revised it and we prefer to leave it in open nomenclature since it does not seem a juvenile of b. zetlandica. recent distribution: shetlands, n. britain (athersuch et al., 1989; hansson, 1998). ostracod bioprovince: celtic (britannic) (fig. 4) fig. 6 bythocythere puncticulata: left juvenile male valve. this specimen is stored in the roc slide n° 2526, partanna (sicily, early calabrian), labelled as bythocythere cf. b. turgida. bar corresponds to 0.1 mm. bythocythere puncticulata: valva sinistra maschile giovanile. l’esemplare è conservato nella collezione ostracodi ruggieri teca n° 2526, partanna (sicilia, calabriano inferiore) con il nome bythocythere cf. b. turgida. la barra corrisponde a 0.1 mm. a revision of the “northern guest” ostracoda (crustacea) occurrence in the quaternary of the … 81 fig. 7 bythocythere zetlandica: (a) left valve from monte mario (roma, latium), santernian age; (gliozzi’s ostracod collection (goc) slide n° m83/4/15). (b) present geographical distribution (dark grey line) and early pleistocene distribution in the mediterranean area (black dot). bar corresponds to 0.1 mm. bythocythere zetlandica: (a) valva sinistra da monte mario (roma, lazio), età santerniano; (collezione ostracodi gliozzi teca n° m83/4/15). (b) distribuzione geografica attuale (linea grigio scura) e distribuzione nel mediterraneo durante il pleistocene inferiore (punti neri) la barra corrisponde a 0.1 mm. ecology: inner circalittoral waters around british coasts (athersuch et al., 1989) fossil distribution in the mediterranean: calabrian (santernian): monte mario (rome, central italy), from the 2° a. islandica level (faranda & gliozzi, 2008). cythere lutea o.f. müller, 1785 (fig. 9) 1785 cythere lutea sp. n. o.f. müller, p. 65, pl. 7, figs. 3-4. 1818 cytherina lutea (o.f. müller) nov. comb. lamarck, p. 125. 1941 cythere lutea o.f. müller sylvester-bradley, p. 27, figs. 15-18 (with full synonimy) recent distribution: kieler bucht, öres, bohuslän, bergen, n. norway, iceland and arctic seas, shetlands, sw british isles, scilly isles, w france (hansson, 1998; freiwald et al., 1998; mackiewicz, 2006); kent coast (isle of thanet) (bruce, 2002); north yorkshire (hull, 1998); from s. norway to n france (athersuch et al., 1989); subfrigid to mild temperate waters of the atlantic and pacific ocean (hanai, 1977). a subspecies (cythere lutea omotenipponica hanai, 1959) reaches the warm temperate climatic zone along the pacific coast of japan (hanai, 1977). ostracod bioprovince: celtic arctic (fig. 4) ecology: the species inhabits shallow waters (30-50 m) with sandy bottom or populated by coralline algae. it withstands mesoto euhaline salinities and a wide range of temperature (-2 to 22°c) (freiwald et al., 1998; frenzel et al., 2010). fossil distribution in the mediterranean: calabrian (sicilian): lo sperone (palermo, sicily) (ruggieri, 1971, 1973). cytheropteron depressum brady & norman, 1889 (fig. 10) 1889 cytheropteron depressum sp. n. brady & norman, p. 447, pl. 34, figs. 39-42. recent distribution: sw british isles, (athersuch et al., 1989; hansson, 1998); scilly isles (neale, 1970). ostracod bioprovince: celtic (britannic) (fig. 4) ecology: inner circalittoral marine environment (athersuch et al., 1989) fossil distribution in the mediterranean: calabrian (santernian): monte mario (rome, central italy), from the 2° a. islandica level (faranda & gliozzi, 2008). fig. 8. bythocythere sp.: left juvenile broken valve. this specimen is stored in the roc slide n° 856 under the name bythocythere cf. b. zetlandica gelasian capocolle clays (forlì, northern italy). bar corresponds to 0.1 mm. bythocythere sp.: valva sinistra giovanile rota. questo esemplare è conservato nella collezione ostracodi ruggieri teca n° 856 col nome bythocythere cf. b. zetlandica gelasiano, argille di capocolle (forlì, italia settentrionale). la barra corrisponde a 0.1 mm. c. faranda & e. gliozzi 82 cytheropteron punctatum brady, 1868 (fig. 11) 1868 cytheropteron punctatum nov. sp. brady, p. 449, pl. 34, figs. 45-48. recent distribution: korshavn, s. norway, bergen, british isles, bay of biscay (hansson, 1998). ostracod bioprovince: celtic norwegian (fig. 4) ecology: penney (1993) collected this species from the silty bottom of the norway channel at a depth comprised between 190 and 270 m, bottom temperature between 6.5-7°c, and euhaline salinity. fossil distribution in the mediterranean: calabrian: tavoliere delle puglie (southern italy) (ruggieri, 1959). crete (sissingh, 1972). calabrian (santernian): valle del tronto (marche, central italy) (pucci, 1956; ruggieri, 1973). vrica (calabria, southern italy) about 10 m above the first occurrence of cytheropteron testudo (colalongo & pasini, 1980; pasini & colalongo, 1994). calabrian (emilian): vrica (calabria, southern italy) (colalongo & pasini, 1980; pasini & colalongo, 1994). cala bianca (marina di camerota, campania, southern italy) (ciampo, 1976). calabrian (sicilian): ficarazzi (palermo, sicily) (ruggieri, 1956, 1973). s. maria di catanzaro (calabria, southern italy) (sissingh, 1973a). monasterace (calabria, southern italy) (greco et al., 1974). cytheropteron testudo sars, 1869 (fig. 12) 1869 cytheropteron testudo nov. sp. sars, p. 173, pl105, fig. 1. recent distribution: lofoten, spitsbergen, koster channell, hardangenfjord (hansson, 1998); laptev sea (n. russia) (stepanova et al., 2003); scoresby sound, w greenland (whatley et al., 1996, 1998; mackiewicz, 2006); murray island (e greenland), newfoundland (benson et al., 1984), norwegian coast down to the skagerrak (ruggieri, 1971, 1973, 1977). the report of this species in the bay of biscay (yassini, 1969) concerns only loose valves. the possible distribution of c. testudo in the southern hemisphere is discussed by several authors (swanson & ayress, 1999; dixon, 2006; jellinek et al., 2006) but this problem is beyond the topic of the present paper. ostracod bioprovince: norwegian arctic (fig. 4) ecology: it is a rather deep species. it as been reported from norway at depths comprised between 80 and 240 m (freiwald et al., 1998 ) and down to 300 m (penney, 1993) at bottom temperatures comprised between 7.0 and 7.4°c. elofson (1941) reports c. testudo from skagerrak at 270 m of depth and from spitzbergen at 150 m at bottom temperatures from -2° to 10°c. fossil distribution in the mediterranean: gelasian: m. s. nicola (sicily) at 68 m (sample 35) (aiello et al., 1996b, 2000; bonaduce & sprovieri, 1984). camerano (forlì, northern italy) (ruggieri, 1977, 1978, 1996). castrocaro (forlì, northern italy) (ruggieri, 1977, 1978, 1996). “calabrian”: kos (greece, aegean sea) (mostafawi, 1981,1986). rhodes (greece, aegean sea) (mostafawi, 1989). zakinthos (greece, ionian sea) (tsapralis, 1981). calabrian (santernian): vrica (calabria, southern italy), about 10 m above the sapropel e (colalongo & pasini, 1980; pasini & colalongo, 1994). ribera (southern sicily) (ruggieri, 1977). cosenza (calabria, southern italy) (ruggieri, 1952b). calabrian (emilian): vrica (calabria, southern italy) (colalongo & pasini, 1980; pasini & colalongo, 1994). imola (northern italy) (ruggieri, 1952a, 1975). mar piccolo (taranto, southern italy) (ciampo, 1971). porto recanati (ancona, central italy) (ruggieri, 1971). località “il carmine” (crotone, calabria, southern italy) (ruggieri, 1952a). località in destra del verdura (sciacca, sicily) (ruggieri, 1973). calabrian (sicilian): le castella (calabria, southern italy) (colalongo, 1966). s. maria di catanzaro (calabria, southern italy) (sissingh, 1973a). ficarazzi (palermo, sicily) (sissingh, 1973b). mar piccolo (taranto, southern italy) (ciampo, 1971). porto recanati (ancona, central italy) (ruggieri, 1971). località “il carmine” (crotone, calabria, southern italy) (ruggieri, 1952a). località in destra del verdura (sciacca, sicily) (ruggieri, 1973). pizzo longo (crotone, calabria, southern italy) (this paper, together with g. truncatulinoides excelsa). tarantian (last pleniglacial): gulf of taranto (moncharmont-zei et al., 1985) adriatic sea (breman, 1976) hemicythere villosa (sars, 1866) (fig. 13) 1866 cythereis villosa nov. sp. sars, p. 42. 1868 cythere villosa (sars) brady, p. 411, pl. 29, figs. 28-32. 1925 hemicythere villosa (sars) sars, p. 182, pl. 84, figs. 1-13. 1941 cythereis (eucythereis) villosa sars elofson, pp. 287288. recent distribution: kieler bucht, öres, bohuslän, north sea, n. norway, iceland, bear island (swalbard), british isles, scilly isles, bay of biscay (hansson, 1998); kent coast (isle of thanet) (bruce, 2002); davis strait (baffin bay) (elofson, 1941), atlantic north america (virginia coast) (hulings, 1966); britain and nw european coasts (athersuch et al., 1989). ostracod bioprovince: celtic arctic (fig. 4) a revision of the “northern guest” ostracoda (crustacea) occurrence in the quaternary of the … 83 fig. 9 cythere lutea: (a) right valve (transmitted light), (b) right valve under sem from sperone locality (palermo), calabrian (sicilian) (roc slide n° 1623); (c) present geographical distribution (dark grey line) and early pleistocene distribution in the mediterranean area (black dot). bar corresponds to 0.1 mm. cythere lutea: (a) valva destra in luce trasmessa, (b) valva destra in scansione elettronica dalla località sperone (palermo, sicilia), calabriano (siciliano) (collezione ostracodi ruggieri teca n° 1623); (c) distribuzione geografica attuale (linea grigio scura) e distribuzione nel mediterraneo durante il pleistocene inferiore (punti neri). la barra corrisponde a 0.1 mm. fig. 10 cytheropteron depressum: (a) left valve from monte mario (roma, latium), santernian age; (goc slide n° m114/1/5). (b) present geographical distribution (dark grey line) and early pleistocene distribution in the mediterranean area (black dot). bar corresponds to 0.1 mm. cytheropteron depressum: (a) valva sinistra da monte mario (roma, lazio), età santerniano; (collezione ostracodi gliozzi teca n° m114/1/5). (b) distribuzione geografica attuale (linea grigio scura) e distribuzione nel mediterraneo durante il pleistocene inferiore (punti neri). la barra corrisponde a 0.1 mm. c. faranda & e. gliozzi 84 fig. 11 cytheropteron punctatum: (a) right valve from monasterace (calabria), sicilian age; (roc slide n° 2313). (b) present geographical distribution (dark grey line) and early pleistocene distribution in the mediterranean area (black dot). bar corresponds to 0.1 mm. cytheropteron punctatum: (a) valva destra dalla località monasterace (calabria, italia meridionale), età siciliano; (collezione ostracodi ruggieri teca n° 2313). (b) distribuzione stratigrafica attuale (linea grigio scura) e distribuzione nel mediterraneo durante il pleistocene inferiore (punti neri). la barra corrisponde a 0.1 mm. fig. 12 cytheropteron testudo: (a) right valve (transmitted light), (b) right valve under sem from “il carmine” locality (crotone, calabria), emilian age; (roc slide n° 924). (c) present geographical distribution (dark grey line), early pleistocene distribution in the mediterranean area (black dot), last glacial maximun distribution in the mediterranean (white circle). bar corresponds to 0.1 mm. cytheropteron testudo: (a) valva destra in luce trasmessa, (b) valva destra in scansione elettronica dalla località “il carmine” (crotone, calabria), età emiliano; (collezione ostracodi ruggieri n° 924). (c) distribuzione geografica attuale (linea grigio scura) e distribuzione nel mediterraneo durante il pleistocene inferiore (punti neri) ed il pleniglaciale (cerchi bianchi). la barra corrisponde a 0.1 mm. a revision of the “northern guest” ostracoda (crustacea) occurrence in the quaternary of the … 85 fig. 13 hemicythere villosa: (a) right valve in transmitted light, (b) left valve under sem from sperone (palermo) (roc slide n° 1640); (c) present geographical distribution (dark grey line) and early pleistocene distribution in the mediterranean area (black dot). bar corresponds to 0.1 mm. hemicythere villosa: (a) valva destra in luce trasmessa, (b) valva sinistra in scansione elettronica dalla località sperone (palermo, sicilia) (collezione ostracodi ruggieri teca n° 1640); (c) distribuzione stratigrafica attuale (linea grigio scura) e distribuzione nel mediterraneo durante il pleistocene inferiore (punti neri). la barra corrisponde a 0.1 mm. ecology: it inhabits marine very shallow to shallow waters with vegetated sandy bottoms and water temperatures that range from 0 to 22°c in mesohaline-euahaline conditions (elofson, 1941; athersuch et al., 1989; frenzel et al., 2010). fossil distribution in the mediterranean: calabrian (sicilian): lo sperone (palermo, sicily) (ruggieri, 1971; 1973, 1980; sissingh, 1976). paradoxostoma abbreviatum sars, 1866 (fig. 14) 1866 paradoxostoma abbreviatum sp. nov. sars, p. 94 recent distribution: s. baltic, öres, bohuslän, holland, bergen, shetlands, british isles, n france, ?bay of biscay (hansson, 1998); british isles, norway, baltic, helgoland and n france (athersuch et al., 1989); north yorkshire (hull, 1998). ostracod bioprovince: celtic (?gasconyan) norwegian (fig. 4) ecology: p. abbreviatum is typical of mesohaline to euhaline very shallow to shallow waters (0.2 to 20 m)with vegetated and highly oxygenated sandy bottoms, and water temperatures that range from 2 to 5°c (elofson, 1941; athersuch et al., 1989; frenzel et al., 2010). fossil distribution in the mediterranean: calabrian (santernian): monte mario (rome, central italy), from the 2° a. islandica level (faranda & gliozzi, 2008). paradoxostoma ensiforme brady, 1868 (fig. 15) 1868 paradoxostoma ensiforme sp. nov. brady, p. 460, pl. 35, figs. 8-11. recent distribution: bohuslän, holland,?s and w norway, shetlands, sw british isles, n france, ?bay of biscay (athersuch et al., 1989; hansson, 1998); north yorkshire (hull, 1998). ostracod bioprovince: celtic (?gasconyan) norwegian (fig. 4) ecology: the species inhabits mesohaline to euhaline very shallow to shallow waters (5 to 18 m on vegetated bottom and down to 50 m on detritic sands), and a wide range of water temperatures (elofson, 1941; athersuch et al., 1989; frenzel et al., 2010). fossil distribution in the mediterranean: calabrian (santernian): monte mario (rome, central italy), from the 2° a. islandica level (faranda & gliozzi, 2008). c. faranda & e. gliozzi 86 fig. 14 paradoxostoma abbreviatum: (a) right valve from monte mario (roma, latium), santernian age; (gocollection slide n° t30/1). (b) present geographical distribution (dark grey line) and early pleistocene distribution in the mediterranean area (black dot). bar corresponds to 0.1 mm. paradoxostoma abbreviatum: (a) valva destra proveniente da monte mario (roma, lazio), età santerniano; (collezione ostracodi gliozzi teca n° t30/1). (b) distribuzione stratigrafica atuale (linea grigio scura) e distribuzione nel mediterraneo durante il pleistocene inferiore (punti neri). la barra corrisponde a 0.1 mm. fig. 15 paradoxostoma ensiforme: (a) left valve from monte mario (roma, latium), santernian age; (goc slide n°t30/2). (b) present geographical distribution (dark grey line) and early pleistocene distribution in the mediterranean area (black dot). bar corresponds to 0.1 mm. paradoxostoma ensiforme: (a) valva sinistra proveniente da monte mario (roma, lazio), età santerniano; (collezione ostracodi gliozzi teca n°t30/2). (b) distribuzione geografica attuale (linea grigio scura) e distribuzione nel mediterraneo durante il pleistocene inferiore (punti neri). la barra corrisponde a 0.1 mm. paradoxostoma tenuissimum (norman, 1869) (fig. 16) 1869 bythocythere tenuissimum sp. nov. norman, p. 294. 1870 xiphichilus tenuissimum (norman) brady, p. 369, pl. 12, figs. 6-9. 1889 machaerina tenuissima (norman) brady & norman, p. 238, pl. 21, figs. 13-14. 1985 paradoxostoma tenuissimum (norman) horne & whittaker, p. 182, figs. 30a-e, 31a-f, 32a-e, 44d-e, 45d-e recent distribution: british isles from scotland and shetlands (hansson, 1998; athersuch et al., 1989). ostracod bioprovince: celtic (britannic) (fig. 4) ecology: p. tenuissimum is considered one of the most deep species of the genus, inhabiting waters down to 50-100 m (athersuch et al., 1989). fossil distribution in the mediterranean: calabrian (emilian): cosenza (calabria, southern italy), together with hyalinea balthica (ruggieri, 1975). calabrian (sicilian): casa schifo (between gela and vittoria, sicily) (ruggieri, 1975). tarantian (last pleniglacial): adriatic sea (bonaduce et al., 1976; breman, 1976) semicytherura angulata (brady, 1868) (fig. 17) 1868 cytherura angulata sp. nov. brady, p. 440, pl. 32, figs. 22-25. 1957 semicytherura angulata (brady) wagner, p. 84, pl. 39. recent distribution: kieler bucht, belt sea, bohüslan, a revision of the “northern guest” ostracoda (crustacea) occurrence in the quaternary of the … 87 hölland, hardnger fjord, iceland, shetlands and sw british isles (hansson, 1998); british isles and northern europe (athersuch et al., 1989); ?bay of biscay (yassini, 1969). ostracod bioprovince: celtic (britannic) norwegian (fig. 4) ecology: the species inhabits mesohaline to euhaline very shallow to shallow waters (5 to 10 m) in ma rine and estuarine conditions, with vegetated bottom, and a wide range of water temperatures (elofson, 1941; athersuch et al., 1989). fossil distribution in the mediterranean: calabrian (emilian): apennine piedmont near forlì (northern italy) (ruggieri et al., 1976). calabrian (emilian or sicilian): chirco, digerbato and ciantrato (marsala, sicily) (ruggieri, et al. 1977). fig. 16 paradoxostoma tenuissimum: (a) broken left valve from cosenza (calabria), emilian age; (roc slide n° 745); (b) present geographical distribution (dark grey line), early pleistocene distribution in the mediterranean area (black dot), last glacial maximun distribution in the mediterranean (white circle). bar corresponds to 0.1 mm. paradoxostoma tenuissimum: (a) valva sinistra rotta proveniente da cosenza (calabria, italia meridionale), età emiliana; (collezione ostracodi ruggieri teca n° 745); (b) distribuzione geografica attuale (linea grigio scura) e distribuzione nel mediterraneo durante il pleistocene inferiore (punti neri) e il pleniglaciale (cerchi bianchi). la barra corrisponde a 0.1 mm. fig. 17 semicytherura angulata: (a) right valve in transmitted light, (b) right valve under sem from digerbato well (marsala), emilian or sicilian age; (roc slide n° 2622); (c) present geographical distribution (dark grey line) and early pleistocene distribution in the mediterranean area (black dot). bar corresponds to 0.1 mm. semicytherura angulata: (a) valva destra in luce trasmessa, (b) valva destra in scansione elettronica provenienti dal pozzo digerbato (marsala, sicilia), età emiliana o siciliana; (collezione ostracodi ruggieri teca n° 2622); (c) distribuzione geografica attuale (linea grigio scura) e distribuzione nel mediterraneo durante il pleistocene inferiore (punti neri). la barra corrisponde a 0.1 mm. c. faranda & e. gliozzi 88 4. discussion and conclusion the critical revision of the “cold” ostracods recovered in the mediterranean quaternary proposed in this paper reduces the number of the true “northern guest” from the 22 species reported in literature only to 12 confirmed taxa. they are generally rare within their assemblages, often represented only by a single specimen from a single locality. only c. testudo and c. punctatum have been reported with a wide mediterranean geographical distribution in italy and in the aegean sea. almost all the “northern guest” ostracods have their present southernmost distribution in the celtic bioprovince except b. turgida and c. testudo that are more northern species, presently widespread only from the norwegian to the arctic bioprovince. data on the ecological requirements of the listed “cold” ostracods lead to divide them into three groups on the basis of the water depth: the shallow (infralittoral) species (c. lutea, h. villosa, p. abbreviatum, p. ensiforme, and s. angulata); the circalittoral species (a. dunelmensis, b. turgida, b. zetlandica, c. depressum, and p. tenuissimum); the circalittoralupper epibatial species (c. punctatum and c. testudo). temperature ranges are known only for few species, but two groups can be recognized: eurythermal species, such as c. lutea and h. villosa, and cold stenothermal species as c. punctatum, c. testudo and p. abbreviatum. the temperature ranges of this latter group (-2 to 10°c) does not fit neither the monthly mean temperatures of the mediterranean superficial waters for january and july 2011 (fig. 18) nor the mean annual temperature of the mediterranean superficial waters as inferred by kuhlemann et al., 2008 for the last glacial maximum (fig. 19). their presence in the quaternary mediterranean deposits can be explained by their settlements in deeper habitats, in search of lower temperatures: c. punctatum and c. testudo have been recovered in the mediterranean in associations with lower epibathial species, whereas the epiphytal inner infralittoral p. abbreviatum moved towards the outer infralittoral bottoms. on the contrary, in the quaternary, the eurythermal species occurred in the mediterranean in the same range of depths as present. the conclusion reached with this revision leads to a comparison with the “northern guest” molluscs (malatesta & zarlenga, 1986). quaternary “northern guest” ostracod species are fewer than mollusc species (twelve against fifty-three) but in both cases they are generally rare within their assemblages. in fact also among molluscs, very few species can be considered common (> ten localities: pseudamussium septemradiatum (müller, 1776), arctica islandica (linnaeus, a revision of the “northern guest” ostracoda (crustacea) occurrence in the quaternary of the … 89 fig. 20 stratigraphic distribution of the “northern guest” ostracods in the mediterranean area. distribuzione stratigrafica degli ostracodi “ospiti nordici” nel mediterraneo. 1767), lunatia montagui (forbes, 1838), neptunea contraria (linnaeus, 1771), buccinum undatum linnaeus, 1767 and buccinum humpreysianum bennet, 1825). like the “northern guest” molluscs, also ostracods entered the mediterranean at different times (fig. 20), being more abundant in the sicilian substage. “northern guest” molluscs were reported also from the last glacial maximum deposits of cap créus (mars, 1958), confirming that the migration of “cold” species into the mediterranean followed the cyclic cold climate oscillations. “northern guest” ostracods have been mainly recorded in the lower quaternary sediments, but one study on the last glacial maximum ostracods (moncharmont-zei et al., 1985) reports the presence of cytheropteron testudo in deposits of the ionian sea. additionally, in some papers dealing with modern mediterranean ostracod faunas some other “cold” species are listed, recovered as loose valves. for example, breman (1976) and bonaduce et al. (1976) reported loose valves of cytheropteron testudo, bythocythere turgida and paradoxostoma tenuissimum, whose presence in the adriatic sea could be better linked to reworked remains of the last glacial maximum. in conclusion, this revision of the “northern guest” ostracods suggests that they could be a valuable tool for interpreting cold climatic events in a sedimentary succession, but further studies are needed to improve the knowledge of the quaternary “cold” ostracod contingent in the mediterranean. acknowledgments we are deeply indebted with dr. carolina d’arpa, curator of the museum “g.g. gemmellaro” of palermo, who kindly made available to us the ruggieri’s ostracod collection for the revision of true or supposed ostracod “northern guests”. we whish to thank our referees ilaria mazzini and diana barra who helped us to improve this paper. references aiello g., barra d. & bonaduce g. 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(1979) répartition des ostracodes dans une série marine régressive d’âge pliocène dans la région d’algérie. rev. micropaléont., 22 (2), pp. 89-124. ms. ricevuto il 4/05/2010 testo definitivo ricevuto il 7/09/2010 ms. received: may 4, 2010 final text received: september 7, 2010 amq30(1) 3 pandolfi b.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 30 (1), 2017, 25 40 a reassessment of the infills and faunal assemblages of karst cavities known as ventarole in salento (apulia, southern italy): a multidisciplinary investigation on cava donno (corigliano d’otranto, lecce) luca pandolfi 1, marcello a. mannino2,3, sahra talamo3, leonardo salari4, paolo sansò5, sandro sublimi saponetti6, eligio vacca6, deborah vicari4, michael p. richards3,7, carmelo petronio4 1 dipartimento di scienze, sezione di geologia, università degli studi roma tre, roma, italy 2 department of archaeology, school of culture and society, aarhus university, højbjerg, denmark 3 department of human evolution, max planck institute for evolutionary anthropology, leipzig, germany 4 dipartimento di scienze della terra, università sapienza, roma, italy 5 dipartimento di scienze e tecnologie biologiche ed ambientali, università del salento, ecotekne, lecce, italy 6 dipartimento di biologia, università degli studi di bari, bari, italy 7 department of anthropology, university of british columbia, vancouver, canada corresponding author: l. pandolfi <luca.pandolfi@uniroma3.it > abstract: the karstic areas of apulia in se italy are characterized by fissures locally called ventarole, which are known to contain bones of pleistocene mammals. these bone assemblages have been commonly associated to the late pleistocene, based on stratigraphic, geomorphological and biochronological observations. we undertook palaeontological, radiocarbon and isotope analyses to verify whether the animal remains from the quarry of cava donno, near corigliano d’otranto (apulia), were all actually of pleistocene age. our study shows that the infills of the ventarole contain, along with late pleistocene bones attributable to the melpignano faunal unit, holocene vertebrate skeletal remains. the deeper red clay infill at cava donno contains fauna of pleistocene age, whilst the upper dark-reddish clayey sands contain mainly the bones of domestic animals and of a modern human. the ams radiocarbon date, obtained to establish the age of this human from the ventarola, coincides with the neolithic period. carbon and nitrogen isotope analyses on the same bone collagen suggest that the diet of this individual was similar to that of other neolithic humans from italy. the individual from cava donno had a balanced diet, centred upon terrestrial foods, with nutrients acquired both from vegetal and animal resources. the combined palaeontological, radiocarbon and isotopic data presented here suggest that crypto-solution processes occurred at cava donno both in the last interglacial and, to some extent, also around the holocene climatic optimum. this implies that ventarole karst infills may contain vertebrate remains of pleistocene and holocene age and that, therefore, the assemblages from them probably need revising because they may not all date back to the early late pleistocene. keywords: karst cavities; pleistocene; early holocene; neolithic; carbon and nitrogen isotope analyses 1. introduction the salento peninsula (apulia, southern italy) is well-known for the presence of karst cavities containing deposits that preserve rich paleontological and archaeological bone assemblages of pleistocene and holocene age (e.g., mirigliano, 1941; borzatti von löwenstern, 1966; palma di cesnola, 1966; spennato, 1981; de giuli, 1983; cremonesi et al., 1984; corridi, 1987; bologna et al., 1994; rustioni, 1998; vacca, 2006; petronio & pandolfi, 2008; benazzi et al., 2011; pandolfi & petronio, 2011; boscato & crezzini, 2012; pandolfi & tagliacozzo, 2013). this area represents, therefore, an important repository of invaluable data for reconstructing the evolution of past environments during the pleistocene and holocene in southern europe. abundant mammal remains have been recovered in different karstic features of the salento peninsula, such as in cave deposits (e.g., blanc, 1920, 1928; maviglia, 1955; orlandi & cigna, 1956; cardini, 1958a; borzatti von löwenstern, 1966, 1971; giusti, 1979; dantoni & nardi, 1980; campetti, 1986; boscato & crezzini, 2012), in stratified sediments at the bottom of dolines (corridi, 1987), and in sub-vertical or funnel-shaped fissures, locally known as ventarole, filled with reddish sediments (mirigliano, 1941; cardini, 1958b; de giuli, 1983; bologna et al., 1994; rustioni et al., 1994). the ventarole are located within the pietra leccese formation and outcrop in several quarries located in the districts of melpignano, corigliano d’otranto and maglie (lecce; fig. 1). most of the fossil mammal assemblages collected from the karstic fillings of the ventarole have been attributed to the early late pleistocene (bologna et al., 1994; bedetti et al. 2004; cipullo et al., 2006; petronio et al., 2007; petronio & pandolfi, 2008; pandolfi & petronio, 2011). these assemblages include skeletal remains of carnivores (panthera spelaea, crocuta crocuta, canis lupus), elephants (palaeoloxodon antiquus), rhinoceroses (stephanorhinus hemitoechus), horses (equus hydruntinus, equus ferus), hippopotamuses 26 pandolfi l. et al. (hippopotamus amphibius), bovids (bos primigenius, bison priscus), cervids (cervus elaphus, dama dama) and other taxa (mirigliano, 1941; cardini, 1958b; de giuli, 1983; bologna et al., 1994; bedetti et al., 2004; cipullo et al., 2006; petronio & pandolfi, 2008; pandolfi & petronio, 2011). during a paleontological field survey, several fossil remains belonging to oryctolagus cuniculus, lepus corsicanus, c. lupus, p. spelaea, c. crocuta, e. ferus, c. elaphus, d. dama and b. primigenius were collected from several karst fillings exposed at cava donno, a quarry near the town of corigliano d’otranto. in addition to some of the above-mentioned taxa, remains of domestic mammals and of homo sapiens were recovered from an n-shaped karst fissure. the cava donno ventarola investigated in this paper is characterized by red clayey infills in its sub-vertical cavities and by red clayey and dark reddish clayey sands in its oblique cavity (fig. 2). the late pleistocene and holocene mammal remains recovered from this n-shaped fissure are the object of the present paper. the aims of this study were: 1. to study the bone assemblage from cava donno in an attempt to understand its formation and relative chronology; 2. to undertake ams radiocarbon dating and isotope analyses on the bone collagen of the human individual whose remains were recovered from the ventarola to establish its absolute chronology and reconstruct its diet. moreover, the diachrony of the karst fillings from cava donno and from the districts of melpignano, corigliano d’otranto and maglie is discussed. fig. 1 a: location map of the investigated area; b: location map of the cava donno quarry and geological scheme of the s. sidero (melpignano) area. legend: a) calcarenites (lower pleistocene); b) leuca formation and sabbie di uggiano (pliocene); c) pietra leccese (upper miocene); d) calcari di altamura (upper cretaceus); e) fault slope; f) quarry; h) urbanized area; i) investigated area. fig. 2 n-shaped karst cavities of cava donno (melpignano, lecce). the arrows indicate the position of the humerus (1) and coxal bone (2) of homo sapiens. the white line indicates the dark reddish clayey sands that yielded the holocene fauna whilst the red line indicates the red clay with pleistocene fauna. 27 reassessment of the ventarole karst cavities 2. geomorphological and geological framework the landscape of the area between the presentday villages of corigliano d’otranto, melpignano and maglie in apulia is marked by a narrow morphostructural ridge stretching in a nw-se direction and bordered by two low steep scarps (fig. 1). this ridge characterizes the mean axis of southern salento from the area to the south of the village of botrugno to the nw of the village of corigliano d’otranto, where it reaches its maximum relief and acquires the local name of “serra di corigliano” (palmentola, 1987). rocks belonging to the pietra leccese formation (upper miocene) extensively crop out in correspondence to the morpho-structural ridge. they are biomicrites mainly constituted by calcareous plankton, generally yellowish in colour except in the uppermost levels which are greenish, because of the high glauconitic content. this lithostratigraphic unit is composed by indistinct thick strata and characterized by intense bioturbation, as well as by high macrofossil content, mainly of bivalves (above all pectinids) and echinoderms (spatangids). fossils are both dispersed and concentrated in lenses or layers; shark teeth are very frequent (largaiolli et al., 1969; balenzano et al., 2003). the unit is transgressive on the mesozoic basement (calcari di altamura formation, upper cretaceous) by means of a conglomerate layer marked by phosphatized clasts and fossils, as well as apatite nodules. the mesozoic limestones crop out in the northernmost area of the ridge, roughly from the village of corigliano d’otranto to the nw. the contact between mesozoic limestone and miocene calcarenites is well exposed along the salento manufatti s.r.l. quarry cliffs. the north-eastern border of the ridge, constituted by a degraded fault scarp, comprises at its foot a small outcrop of upper pliocene calcarenites belonging to the uggiano la chiesa formation (bossio et al., 1987). smaller outcrops of lower pliocene rocks (“formazione di leuca”), uplifted by faulting, can be recognized at the lowermost part of the scarp (fig. 3). above the ridge is a plain characterized by numerous quarries, given that upper miocene rocks are used for the production of blocks and slabs. sub-vertical karst cavities (i.e. ventarole), are present along the cliff sections of the quarry, infilled with reddish sandy-clayey deposits that cover the plain above the ridge. the transverse section of these cavities is still not well defined. the ventarole are spaced about ten meters from each other and reach depths of more than 10 m from soil surface. their maximum width is generally less than 1 m, although locally, cavities of up to 5-6 meters can be recognized. cavities become narrower downwards, terminating always in a joint plane (fig. 4). the strong structural control in the development of these landforms is testified by the morpho-structural analysis performed fig. 3 schematic geological section of the investigated area. legend: a) calcari di altamura (upper cretaceus); b) pietra leccese (upper miocene); c) leuca formation (lower pliocene); d) sabbie di uggiano (upper pliocene); e) fault; f) supposed fault. fig. 4 longitudinal section of the karst cavities (ventarole) recorded at cava donno (s. sidero, melpignano, lecce). fig. 5 azimuthal distribution of frequency of the ventarole outcropping at cava donno (s. sidero, melpignano). on three adjacent quarry cliffs (the area is marked by a bold circle in fig. 1). this analysis established that the ventarole developed mainly along nw-se and nnessw directions, following the main regional joint system (di bucci et al., 2011) (fig. 5). the karst cavities are completely filled by deeplyweathered dark-reddish clayey sands without definite sedimentary structures. in the wider cavities, reddish clayey sands are covered by less-weathered orange sands with a small clay content first and by greyish sands, about 1 m thick, further up the sequence. 3. materials and methods the human remains collected at cava donno (stored at the department of biology, university of bari) include an incomplete left humerus and an incomplete right os coxae. the morphometric values of the humerus and pelvis are reported in table 1. the methodology adopted follows martin & saller (1957-1962); additional measurements were obtained to estimate the length of the humerus and to evaluate the coxal bone proportions (see caption to table 1 for references). the faunal remains are currently housed at the dipartimento di scienze della terra, sapienza università di roma and are attributable to wild and domestic taxa. the remains were morphologically and morphometrically compared with several specimens from zoological and paleontological collections of the abovementioned department, in order to ascertain their taxonomic attribution. wild and domestic taxa belonging to the same genera (i.e., canis, equus and bos) were identified to species on morphological and morphometric basis, as well as on their conservation status. the specimens collected from the red clayey fillings are, in fact, well fossilized and encrusted with red-coloured soil, whereas the specimens collected from the dark-reddish clayey sands are not mineralized and are brown in colour. human and faunal remains from cava donno were sampled to establish the chronology and diet of the homo sapiens recovered at this site. bone collagen was extracted for this purpose using the pre-treatment method described by talamo & richards (2011), which includes an ultrafiltration step with sartorius “vivaspin 15” 30 kda ultrafilters. abbreviations: i, lower incisor; p, lower premolar; m, lower molar; la, articular width; dapolb, anteroposterior diameter of the oleocranon at the level of the beak; dapol, antero-posterior diameter of the oleocranon over the beak; ddt, distal transverse diameter; ddap, distal antero-posterior diameter; dpt, proximal transverse diameter; l, length; n, number of specimens. 4. palaeontological results and laboratory analyses 4.1. fossil remains from the red clay infill erinaceus europaeus this species is represented by a complete hemimandible with i1, p3, m2 and m3. oryctolagus cuniculus this species is represented by several cranial and postcranial remains. the morphology and morphometry of these remains are in agreement with the general features of the species reported by barone (1974, 1981), iacoangeli (1996) and angelci & spagnesi (2008). lepus corsicanus a fragmented femur, four ulnae, a fifth metatarsal and three fragmented mandibles can be referred to the hare. the anterior lower premolar (p3) does not display the crenulation on the posterior edge of the hypoflexid, which frequently occurs in l. europaeus. in addition, the crenulation on the internal side of the hypoconid in the studied specimens is absent, whereas a deep and oblique entrance on the internal side of the hypoconid can be present on p3 of l. europaeus. the paraflexid on the antero-lingual border is absent on the studied specimens as usually observed in l. corsicanus, whereas a deep paraflexid or parafosetid is usually present in l. europaeus (see palacios, 1996). the postcranial remains can also be assigned to l. corsicanus. microtus (terricola) savii this small rodent is represented by five hemimandibles. the first lower molar on these specimens displays seven triangles, the fourth and the fifth of them are confluent to form the pitymyan rhombus (see nappi & contoli, 2008, and references therein). tab. 1 morphometric values of the human remains from cava donno (melpignano, lecce). *martin and saller, 1957-1962; **estimate (salles et al., 2009); ism: ischium length, modified (novotny, 1986); ismm: ischium length, post-acetabular (schulter-ellis et al., 1983); ss, sa: spino-sciatic and spinoauricular lengths (gaillard 1960); ^cotylo-sciatic index (sauter & privat, 1955). 28 pandolfi l. et al. canis lupus two lumbar vertebrae, a proximal epiphysis of ulna, a first phalanx and an upper canine can be assigned to c. lupus. the remains are large in size, in particular the ulna (la = 22.4 mm; dapolb = 31.3 mm; dapol = 28.2 mm). the morphometry of the ulna and the presence of a strong muscular impression suggest that this specimen is slightly larger than the extant c. lupus from the abruzzi region (salari, unpublished data). equus ferus the following remains are assigned to this taxon: a distal epiphysis of humerus (ddt = 82.1 mm; ddap = 90.0 mm), a first posterior phalanx (la = 89.5 mm; dpt = 58.5 mm; ddt = 49 mm), two fragments of second and fourth vestigial metapodials and a lower deciduous tooth. the morphology and morphometry of these remains resemble those of the equid from tana delle iene (brindisi, southern italy), which is late pleistocene in age (conti et al., 2010). bos primigenius a first upper molar (l = 32; la = 26), which displays a wide and developed entostyle (sala, 1986), and a large first phalanx are referred to the aurochs. cervidae indeterminate cervidae is represented only by a thoracic vertebra of a young individual and an attribution to red deer rather than fallow deer is not possible. 4.2. fossil remains from the dark-reddish clayey sands homo sapiens: humerus this humerus lacks the proximal portion, including the articular head and the surgical neck. the metaphyse preserves part of the bicipital groove and the crests of the greater and lesser tubercles (fig. 6). the residual length of the humerus is of approximately 246 mm. the bone has been reconstructed from two corresponding fragments broken distally to the middle of the shaft. the distal epiphysis is complete, yet slightly damaged on the distal articular surfaces. the estimated length of the humerus (m1) was calculated from the regression, as proposed by salles et al. (2009) on the basis of a recent sex-aggregated sample of adult individuals belonging to various populations. an estimated value of 296.6 mm (±13.5 mm) was obtained from the average values of three different regressions (fig. 7). the method proposed by steele (1970) fig. 6 homo sapiens from cava donno (melpignano, lecce), humerus in anterior (a), posterior (b), lateral (c) and medial (d) views. 29 reassessment of the ventarole karst cavities allowed us to obtain estimated values of between 295.7 and 298.2 mm. a mean value of 282.6 mm was reported by formicola & franceschi (1996) for a neolithic european sample of 27 females (fig. 7). these values do not differ significantly (t-test, p = 0.200) from the mean values obtained for a recent apulian female sample (287 mm ±16.4 mm, n = 40; introna et al., 1994). three sexually dimorphic features of the posterior distal humerus were evaluated (rogers, 1999). the trochlear constriction is intermediate, but the shape of the trochlea tends to be symmetrical with the margin of the capitulum. the shape of the olecranon fossa is oval and the medial epicondyle is angled. taking these features into account, the cava donno humerus could be assigned to a category of “probable female” (falys et al., 2005). considering morphometric values, the last circumference of the shaft (m7 = 52.0 mm) falls within the dimensional range of female individuals from neolithic apulia (fabbri & lonoce, 2011). a discriminant function, calibrated on a recent apulian population (f.n. 10; 90% correctly classified), places the specimen from cava donno within the area occupied by female individuals, thus classifying the humerus as female (introna et al., 1994). two female humeri from malerba (mlt2a, mlt2b, scattarella et al., 1997, 2001) and a male humerus from cala colombo (cc17, pesce delfino et al., 1977) are correctly assigned to gender, based on the discriminant function analysis performed for the specimens from cava donno, in agreement with their morphological features. it is well-known that comparisons between modern and ancient human remains, of which little is known on sexual dimorphism, may be inadequate; such comparisons, hence, represent mere evaluations relative to the modern variability. the stature was estimated based on the method proposed by formicola & franceschi (1996). the values obtained are 154.7 cm for the least squares and 155.8 cm for the major axis formulae respectively. similar values (156 cm) are obtained using the methods of sjøvold (1990) and trotter & gleser (1952, 1977; 156 cm, black females). figure 7 shows the estimated heights for some female individuals from neolithic apulia compared with those of cava donno (humerus least square equation; formicola and franceschi, 1996). according to formicola (1983, 1989), the estimated stature for the neolithic italian sample spans between 148 and 156 cm, whereas the estimated stat ure for ligurian female samples (8 individuals) has an average value of 150.6 cm. an average value of 151.4 cm (± 2.94 cm) was reported for a sample of 11 female individuals from the central apulian area (barbieri et al., in press). the estimated stature for the cava donno specimen is relatively low compared with recent populations (martin & saller, 1957-1962), but relatively high compared with the neolithic sample. the age at death, referable to approximately the fourth decade, is derived from the absence of any residual epiphyseal fusion line, as well as from the presence of moderate signs of lipping on the articular surfaces. the proximal third appears laterally curved in the anterior view, the convexity being accentuated by the attachment of the pectoralis major. the midshaft section of the diaphysis is flattened mediolaterally. according to the robusticity index (m7/1 = 17.2), the bone is relatively gracile, but the attachment of the pectoralis major is hypertrophic, robust and bounded by light, but well defined, radiating lines (mariotti et al., 2007); furthermore, the insertion for the brachioradialis muscle is well expressed. the attachment for the deltoid is, instead, less well-defined, with the surface wrinkled and uneven. this profile may indicate activities requiring considerable involvement of the shoulder joint or intense manipulation. the cross-section index of the shaft demonstrates eurybrachia near the platybrachia (m6/5=77.0). for two female individuals from serra cicora (t6b, t10a) a eurybrachic index is reported (fabbri & lonoce, 2011); eurybrachia is also recorded for passo di corvo (facchini, 1983) and for four female humeri from central apulia (barbieri et al., in press). differences in lifestyles and nutritional deficiencies, especially in early childhood, affect the bone mass and cortical bone thickness. for these reasons, in the long bones, the development of the cortex of the shaft is a reliable indicator of nutritional status (larsen, 1999). in cava donno, the percentage of the cortical area (ca = 79.7%) is higher than the mean values reported for 11 neolithic females from central apulia (69.5 ± 7.9) (barbieri et al., in press). the crosssectional moments of inertia, proportional to the bending rigidity of the bone in the sagittal and medio-lateral planes, are instead among the lowest (imax=4316: imin=1754). in the cava donno humerus, therefore, a relatively low degree of biomechanical stress is associfig. 7 stature (in cm) obtained from the length of the humerus from cava donno (cdonno) and comparison with several neolithic females from central and southern apulia (serra cicora (sct6b, sct10a; fabbri & lonoce 2011); malerba (mat2a, mat2b); polignano madonna di grottole (pmgr; scattarella & de lucia, 1988); palagiano (pal7b, barbieri et al., in press), with a sample of european neolithic females (neoff, formicola e franceschi 1996: mean ±1sd) and with a recent apulian sample (prec, introna et al. 1994; mean ±1sd). 30 pandolfi l. et al. ated with a balanced nutrition (as discussed below). homo sapiens: coxal bone the hipbone lacks the pubis, from the ramus superior to the anterior border of the acetabulum, and from the ramus inferior to the ischial tuberosity (fig. 8). the bone has been reconstructed from two large fragments which include the ilium and part of the ischium with a relatively complete acetabular cavity. two small fragments, one of the ischial tuberosity and one of the iliac spine, also belong to the same specimen. as with the humerus, the hipbone is also reddish-brown and partially covered by soil residues. the bone is relatively short, the maximal height (182.8 mm) falls within the range of the modern apulian female sample, but is considerably smaller than the mean value of the same sample (193.2 ± 8.6, n = 63) (vacca & di vella, 2012). the iliac width (151.0 mm) is comparable, instead, with the average value of the same population (152.4 mm ± 6.5, n = 57). the sigmoid curvature of the iliac crest is rather weak, the iliac fossa is moderately concave and the gluteal lines poorly marked. the muscle attachments on the ischial tuberosity are well defined, the bone surface appears finely wrinkled in relation to the flexion of the leg on the thigh. the iliac tuberosity is well developed and elevated with respect to the auricular facet, a marked post-auricular sulcus separates the two features; on the margin of the facet, moderate lippings of osteophytes can be observed. interosseous groove and iliac tuberosity play an important role in maintaining the stability of the pelvic girdle (andersen, 1986), it is therefore possible that these structures relate to sacroiliac ligament stress and strain. the coxal bone displays at least three morphological characteristics that suggest attribution to a female individual: preauricular sulcus, a composite arch and the form of the sciatic notch. the notch is wide, the anterior and posterior part diverging with a certain degree of asymmetry, yet without recursivity of the posterior ramus. the posterior ramus, normally shorter than the anterior, is instead longer. it is possible that this configuration is due to the same biomechanical stresses discussed in relation to iliac tuberosity and interosseous groove. the cotylo-sciatic index (m15.1/14.1 = 136.4) is comparable with the average values obtained from the recent apulian sample cited above (134.5 ±11.2, n = 82). two discriminant functions calibrated on the same sample (f.n. 7 and 8; vacca & di vella, 2012), suggest that the specimen from cava donno is a female. by fig. 8 homo sapiens from cava donno (melpignano, lecce), coxal bone in lateral (a) and medial (b) views. 31 reassessment of the ventarole karst cavities using the same functions, two coxal bones from malerba (mlt1, male; mt2b, female) are correctly assigned to gender, in agreement with their morphological characteristics. the equations defined by murail et al. (2005) for a worldwide hipbone metrical database also classify cava donno as female (pf ≥0.95). the age at death was estimated from auricular surface morphology: the transverse organization is almost absent, the bone surface has micro and macroporosity and slight retroauricular and apical activity is present. this configuration leads to an estimate of age at death at least in the fourth decade of life (lovejoy et al., 1985). the stature was estimated based on the height of the coxal bones and the diameter of the articular head of the femur (36.8 mm). the latter was obtained from the diameter of the acetabulum and considering the linear regression, as reported by giroux & wescott (2008) and holliday (2000). the values obtained, 153.2 cm (white female) and 153.9 cm (black female), are comparable with those estimated for the humerus of cava donno. based on the femoral head diameter, a body mass of 48.7 kg is estimated for cava donno (ruff et al., 1991). an average value of 55.7 kg (±5.1) (barbieri et al., in press) was obtained for 6 neolithic female individuals from central apulia. microtus (t.) savii this taxon is represented by a hemimandible and a few cranial remains with the third upper molar in simplex morphology (see nappi & contoli, 2008 and references therein). canis sp. a cervical vertebra of a young individual and a fragmented thoracic vertebra can be assigned to this genus. unfortunately, the morphology and morphometry of these specimens are not useful to distinguish between a medium-sized wolf and a domestic dog. bos taurus the morphometric values of an almost complete calcaneum (l = ca. 140 mm) fall within the dimensional range of the neolithic domestic cattle from central and southern italy (wilkens, 1987, 2003). a fragment of horn probably belonging to a female individual, a fragment of skull with the tympanic region, a cervical vertebra, a cuneiform, a sesamoid and a proximal fragment of rib can also be attributed to b. taurus. ovis aries vel capra hircus a few cranial and postcranial remains can be generally referred to ovis vel capra. based on boessnek (1969), barone (1978, 1981) and gudea & stan (2012), a relatively hypsodont third upper molar, a fragmented pelvis and a distal epiphysis of tibia can be attributed to ovis aries (sheep), whereas an almost complete humerus can be referred to capra hircus (goat). 4.3. isotope analyses and radiocarbon dating on bone collagen the human coxal bone sampled for this study yielded an extract that, based on the quality criteria proposed by van klinken (1999), is well-preserved collagen (tab. 2). this extract was ams radiocarbon dated to 6216 ± 23 14c bp (at 95.4% of confidence: 7250-7010 tab. 2 carbon (δ13c) and nitrogen (δ15n) isotope values of bone collagen extracted from human and faunal samples recovered at cava donno. tab. 3 ams radiocarbon date on bone collagen of the human from cava donno, pretreated at the max planck institute for evolutionary anthropology (leipzig). the date was performed at the klaus tschira laboratory of the curt-engelhorn-zentrum archaeometrie in mannheim (mams) and calibrated with the oxcal 4.2 software (bronk ramsey & lee, 2013), using the intcal13 curve (reimer et al., 2013). 32 pandolfi l. et al. animals that feed on these will have higher δ15n values than those grazing in nearby unmanured fields (bogaard et al., 2013). the humans from passo di corvo also have high δ15n values (= 13.3‰), confirming that they fed on plants and/or meat affected by manuring, in the context of a densely populated village the occupants of which were intensively exploiting the landscape around the settlement. this does not appear to have been the case of the human from cava donno, who has an isotopic composition more in line with that of most other neolithic sites in apulia, as well as further afield in the italian peninsula (e.g. giorgi et al., 2005; lelli et al., 2012; goude et al., 2014). 5. discussion 5.1. geomorphological evolution of the karst cavities ventarole are karst landforms that developed along main joints affecting the carbonatic bedrock, because of intense karst processes that occurred below soil cover (crypto-solution processes). these cavities formed mainly in the upper miocene calcarenites of the pietra leccese formation during the late pleistocene, as clearly indicated by fossil fauna. karst landforms due to crypto-solution sharing the same age of ventarole have been recognized in other areas of the salento peninsula (marsico et al., 2003; leucci et al., 2005). in these last cases, solution pipes of cylindrical shape formed because of the isotropy of carbonatic bedrock; pipes are up to 2 m deep and have a diameter length between 0.5 and 1 m. the development of ventarole has been strongly influenced by jointing of miocene carbonatic rocks, so that crypto-solution processes produced the widening of joints forming narrow cavities lengthened downwards. in the scientific literature crypto-solution cavities developed along joints are defined cutters (howard, 1963; palmer, 2009); they have been well studied in indiana (usa), where they are exposed along the quarry cliffs cut into the salem limestone (early carboniferous). the widening of the ventarole causes slow sinking of loose superficial soils, along with fossil remains present inside; these processes turn ventarole into sedimentary traps. 5.2. anthropological and archaeological considerations the biological profile of the human remains from cava donno, represented by a fragmented left humerus and a fragmented right coxal bone, suggest that these two specimens probably belonged to the same individual. this individual was a relatively gracile adult female, of medium stature for the neolithic period, yet with a good level of muscular activity. on the basis of the general features of these human remains and of the comparative data, the bones from cava donno fall within the variability of the neolithic populations of southern italy, similarly to other apulian samples. the lack of artifacts in the infill does not allow us to say more about the cultural attribution and archaeology of the adult female from cava donno. calibrated years bp or 5300-5060 calibrated years bc; tab. 3), a time coinciding with the middle neolithic in apulia (malone, 2003; quarta et al., 2005). of the 11 animal bones sampled, 6 did not yield extracts due to poor preservation. the latter samples are from late pleistocene fauna (i.e. the wolf canis lupus and the auroch bos primigenius), as well as equids and lagomorphs that may also be of similar age. the remaining 5 samples have %c, %n, c:n ratio and % yields (tab. 2) falling within the range for good quality collagen (van klinken, 1999). the δ13c values of the fauna from the site are typical of animals living in terrestrial habitats dominated by c3 plants (mean = -20.4 ± 0.1‰), such as those of the northern mediterranean before the introduction of agriculture (e.g. mannino et al., 2012, 2015). the δ15n values of the large herbivores (i.e. bos taurus and equus ferus) are compatible with those of animals living in temperate environments and of the majority of analyzed domestic fauna from neolithic sites in apulia (e.g. lelli et al., 2012; tafuri et al., 2014). the microtus specimen, on the other hand, lived at a time when the δ15n baseline was relatively high, which likely indicates that this animal was contemporary to a more arid phase than the earlyto-mid holocene. the δ13c value of the human bone collagen indicates that the diet of this individual was based on the consumption of terrestrial dietary protein from c3 plant dominated environments. the δ15n ratio falls within the range of such values obtained for neolithic humans from apulia and the italian peninsula. had the bovids and equids for which we have isotopic data been contemporary to the human specimen analyzed (which is likely given their overlap with values from similar animals from neolithic apulian sites), it could be suggested that this individual had a mixed diet with regular consumption of meat, because its δ15n ratio is ~3.3‰ higher than the mean of the herbivores (= 6.4 ± 0.9‰). however, given the mixed nature of the context of recovery, without dating of each bone we cannot be sure of their exact chronology. for this reason, we compared the isotope values of the human from cava donno with neolithic humans and fauna from apulia (lelli et al., 2012; tafuri et al., 2014). the herbivores from grotta della mura (δ13c = -20.2‰; δ15n = 5.9‰), masseria candelaro (δ13c = -21.1‰; δ15n = 6.3‰) and grotta scaloria (δ13c = -19.9‰; δ15n = 6.0‰), as well as from areas of apulia such as the tavoliere (δ13c = -20.6‰; δ15n = 7.5‰) and the murge (δ13c = -19.9‰; δ15n = 6.9‰), have isotopic compositions similar to those from cava donno (δ13c = -20.4‰; δ15n = 6.4‰). the only neolithic fauna from apulia with a different isotope composition to that of the animals from cava donno and other contemporary sites is that from passo di corvo (tafuri et al., 2014). domestic fauna from this ditched village have mean δ13c ratios of -19.7‰ and mean δ15n ratios of 10.2‰. the nitrogen isotope values of the domesticates from passo di corvo are far higher than those from any other site in se italy and likely a consequence of feeding on plants from manured fields. manuring produces enrichments in the nitrogen isotope composition of intensively-manured plants and, in turn, 33 reassessment of the ventarole karst cavities nevertheless, the radiocarbondate, obtained as part of this study, suggests that the area of cava donno was occupied at least during the middle neolithic, in line with contemporary evidence for intense human occupation in the salento area at sites such as serra cicora, samari, grotta parabita and grotta della trinità (cremonesi, 1978, 1985-86; ingravallo, 1997; quarta et al., 2005; tiberi, 2011; dolfini, 2015). 5.3. palaeontological considerations the mammal assemblages from the ventarole of the study area are known since the nineteenth century (mirigliano, 1941; cardini, 1958b). the vertebrate remains are generally in a good state of preservation and are located at the base and at the top of these karstic infills, without signs of long-distance transport (bologna et al., 1994). in addition, remains are chaotically scattered within these features, lacking specific taphonomic signatures or traces of human activity, and sometimes parts of the same skeletal element occur at different depths (de giuli, 1983; bologna et al., 1994). ventarole karst infills probably accumulated rapidly and the mammalian bone assemblages within them usually appear as coeval in age (bologna et al., 1994). in the first half of the 20th century, several mammalian bone assemblages from different karst cavities in the melpignano area were collected and described by mirigliano (1941) (tab. 4). the presence of several fossiliferous karst infills in the pietra leccese quarries was later also reported by cardini (1958b). however, some of the species reported by cardini (1958b; tab. 4) were recorded in one or a few cavities (e.g., hippopotamus was only recorded at cava motta). de giuli (1983) later described a rich mammalian bone assemblage recovered from a single cavity near maglie at the quarry ‘cava l’, known as san sidero 3 (tab. 4). bologna et al. (1994) described several vertebrate remains, including a tooth of homo cf. neanderthalensis, collected in different ventarole from cava nuzzo near melpignano (tab. 4). the mammal assemblage from cava nuzzo was stratigraphically correlated by bologna et al. (1994) with the fossiliferous levels above the euthyrrenian deposits of several caves along the salento coast (e.g., grotta romanelli, grotta del cavallo, grotta delle striare) and chronologically attributed to the mis 5c-5a, based on stratigraphic, geomorphological and biochronological evidence. in addition, other mammalian assemblages such as those recovered from the districts of melpignano, corigliano d’otranto and maglie, reported by de giuli (1983) and corridi (1987), and those from ossiferous breccias cropping out between 0 and 10 m a.s.l. along the southeastern coast of salento peninsula, from castro marina to otranto (di stefano et al., 1992), were chronologically correlated with mis 5c-5a by bologna et al. (1994). more recently, petronio et al. (2007) established the faunal unit (fu) of melpignano as a new italian biochronological unit for the late pleistocene and proposed the mammal assemblage from cava nuzzo as a local faunal type. the new fu included the classic late pleistocene warm-adapted mammal fauna auctorum, and likely dated back to between ca. 100 and 70 ka (then from 120 to 80 ka; see petronio et al., 2011; pandolfi et al., 2013). the melpignano fu was characterized by the first occurrence of cervus elaphus and dama dama with “evolved” antler morphology, the persistence of large-sized mammals, such as p. antiquus, s. hemitoechus and h. amphibius, and the absence of mammuthus primigenius, coelodonta antiquitatis and other typical cold-adapted mammals auctorum, which defined a new subsequent late pleistocene faunal unit, the ingarano fu (petronio et al., 2007, 2011). in addition, based on the considerations by bologna et al. (1994) and petronio et al. (2007), some authors have also attributed to the early late pleistocene several bird and mammal assemblages from different ventarole at ‘cava l’ near maglie (bedetti et al., 2004) and several fossil remains of carnivores (cipullo et al., 2006), horses (conti et al., 2010) and rhinoceroses (petronio & pandolfi, 2008; pandolfi & petronio, 2011) collected in ventarole from the pietra leccese quarries of the melpignano, corigliano d’otranto and maglie area. in the n-shaped cavity at cava donno, however, the presence of two different faunal associations referable to two distinct epochs (i.e. late pleistocene and holocene) suggest that the mammal assemblages from different karst cavities may not be coeval. in the case of the cavity at cava donno, taxa collected from the red clay deposits (i.e., erinaceus europaeus, oryctolagus cuniculus, lepus corsicanus, microtus (t.) savii, canis lupus, equus ferus, bos primigenius) are in all likelihood older than those collected with the human specimens. a late pleistocene age is suggested for the former taxa, although there is no data to propose a more detailed chronological attribution. the presence of holocene fauna, however, is documented by the occurrence of domestic mammals and, importantly, by the ams radiocarbon date obtained from the human coxal bone (72507010 calibrated years bp). the carbon and nitrogen isotope data from this human specimen fall within the variability recorded for neolithic humans from apulia and italy, suggesting (as discussed above) that the individual in question obtained most of her dietary protein from terrestrial sources that included both vegetal and animal foodstuffs. in addition, the isotopic composition of the well-preserved bone collagen from the fauna, analyzed as part of the present study, is very similar to that of specimens analyzed to date from apulia. this is a further clue that a significant proportion of the vertebrate assemblage from cava donno dates to the holocene. nevertheless, if most of the karst fissures in question were generated and filled with sediments rapidly between the last interglacial (mis 5e) and the early phases of the subsequent climatic deterioration (mis 5c5a, or perhaps up to the beginning of mis 4), we cannot exclude that other cavities in the salento area were also filled during different stages of the late pleistocene. this is probably the case, for instance, of a ventarola at the pietra leccese quarry near sternatia (tab. 4), a locality a few kilometers north of cava donno, the mammal bone assemblage from which was attributed by rustioni et al. (1994) to the second part of mis 4 or to mis 3. 34 pandolfi l. et al. tab. 4 late pleistocene mammalian taxa recorded from the ventarole karst infill discussed in the text. the taxonomy of the recorded species is updated according to several published papers (among others: trocchi & riga, 2005; petronio & pandolfi, 2008; conti et al., 2010; pandolfi & petronio, 2011; petronio et al., 2011; marra et al., 2014; sardella et al., 2014; pandolfi & tagliacozzo, 2015; pandolfi & marra, 2015). 35 reassessment of the ventarole karst cavities 6. conclusions the occurrence of fossil remains belonging to late pleistocene vertebrates suggests that crypto-solution processes at cava donno and in the surrounding area were probably promoted by humid-warm climatic conditions that affected the salento peninsula during the last interglacial period. moreover, the presence of neolithic fauna (attested by this study) could indicate a weak reactivation of crypto-solution processes during the holocene climatic optimum. this likely caused the sinking of the soil cover, constituted by greyish continental deposits that were present at the top of larger ventarole. the presence of holocene and pleistocene mammals in the n-shaped karst fissure from the pietra leccese quarry of cava donno suggests that a critical revision of the chronology of the different bone assemblages recovered within the sediments filling the ventarole scattered throughout the districts of melpignano, corigliano d’otranto and maglie should be undertaken. some fossiliferous deposits could be referred to the early late pleistocene, however, some others could indeed be younger in age. we, therefore, suggest to attribute to the melpignano fu, proposed by petronio et al. (2007), only those deposits that yielded a welldefined association which are analogous in faunal composition and, ideally, abundances with the mammal assemblage of cava nuzzo (e.g., san sidero 3, cava motta). all faunal associations that are not based on mammals useful for establishing biochronological constraints should, therefore, be revised and supported by the application of radiometric dating. an additional outcome of the present study was to obtain carbon and nitrogen isotope data on bone collagen, useful to reconstruct the diet of the neolithic human whose remains were recovered at cava donno. in the absence of information on the settlement and local subsistence economy of the group to whom the individual from cava donno belonged, we can only reach broad conclusions with the data at hand. firstly, we can conclude that neolithic people either intentionally, or not, left traces of their presence at sites such as cava donno. secondly, interpreting the isotope data obtained as part of our study in the context of the database currently available from italian sites, we suggest that the individual from cava donno had a similar diet to that of most of her contemporaries from across italy. the dietary protein consumed by this individual originated overwhelmingly, if not exclusively, from terrestrial sources and both from animals and plants. with the data presented here, we cannot say much more about the proportion of plant to meat consumed. however, given the relatively high δ15n value, it is possible that animal protein acquired by consuming meat and/or dairy products were an important component of the diet of the neolithic human from cava donno. acknowledgements m.a.m., s.t. and m.p.r. thank the max planck society for funding the ams radiocarbon date and the isotope analyses. thanks are due to prof. jean-jacques hublin, director of the department of human evolution, for supporting these analyses and to sven steinbrenner, annabell reiner and lysann rädisch for invaluable technical assistance. we thank the editor a. sposato and the reviewers v. codrea and m. f. rolfo for useful suggestions and comments. references andersen b.c. 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(2003) archeozoologia. cd-rom, schio. 40 pandolfi l. et al. available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 31 (2), 2018, i i quaternary and urban geology adele bertini, maria gabriella forno in the italian peninsula, cities and towns are very complex systems where both environmental and social dynamics interact. urban geology gains insight into earth surface processes by means of a variety of disciplines such as geomorphology, engineering geology, environmental geology, economic geology and hydrogeology. at the same time it proposes strategies for the sustainable use of subsurface resources in urban contexts. on december 15, 2017 at the dipartimento di scienze della terra of florence (italy) aiqua set up a meeting between specialists involved with the various issues of quaternary urban geology. the meeting day focused on the state of knowledge and on the prospects for development and implementation of urban sustainability policies, under non-emergency circumstances but rather for the purpose of prevention. the meeting, which was chaired by a. bertini, m. coli and g. forno, included three invited lectures and eight free oral communications. this volume of amq contains eight of the contributions presented at that meeting. together with the discussions and the final round table, these talks represent aiqua’s first integrated contribution on urban geology in italy. the papers focus on both metropolitan cities, such as rome and turin, and smaller towns; two analyses were directed to unique places such as matera (european capital of culture 2019) and perugia. key case studies address specific urban geology issues; these include in-depth geological and geomorphological analyses focused on different depositional (e.g. volcanic sediments, marine deposits, continental gravels) and morphological (flat, hilly or steep) contexts. the presence of a high number of historically and monumentally valuable archaeological sites in these studies shows how urgent is the need for the implementation of geoscientific teamwork aimed at developing integrated geoarchaeology. the final contribution in the volume is devoted to the use and management of renewable energies, especially geothermal energy. this paper stresses the importance of geosciences for sustainability calls, especially in cities overcrowded with people. all the papers of this volume show that the knowledge of the subsurface and awareness of geoscience issues are vital to the preservation of urban landscape. this expertise contributes to our resilience to natural hazards (e.g. flooding, ground instability, drought) as well as to the development of strategic land-use planning. in this perspective taking early actions to identify actual and potential problems, in urban context, is crucial to effectively face the challenges, which also have economic and social implications. the associated editors take the opportunity to thank all the contributors to this volume. we also thank the many colleagues who reviewed the volume as well as the editor-in-chief of aqm who assisted us with this special issue. the associated editors adele bertini and m. gabriella forno ii available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 217 219 volcano geology and mapping guido giordano dipartimento di scienze, sezione di geologia, università degli studi roma tre, rome, italy corresponding author: g. giordano <guido.giordano@uniroma3.it> abstract: recent development in mapping of italian volcanic areas, both ancient and active, within the framework of the carg project (italian geological map 1:50000 scale) has allowed to define a stratigraphic approach that allows to correctly show the basic lithostratigraphy and the main internal organization of the volcanic succession including the essential periods of quiescence. such innovative approach proves to be very effective for hazard studies, land-planning, management of the geo-cultural heritage. keywords: volcano stratigraphy, mapping, active volcanoes 1. introduction the complex internal architecture of volcanic successions, both at individual volcano scale and at volcanic province scale, is controlled by the interplay between the evolution over time of the volcanic activity, essentially related to the evolution and structure of the magmatic plumbing system, and both climatic and tectonic factors. volcanic edifices may be simple (monogenetic or associated with fixed and short-lived point sources) or very complex (e.g. stratovolcanoes or caldera complexes), where polygenetic activity spans over long time periods and feeding systems are both timeand space-variable. volcano-tectonic and gravitational collapses may not only substantially and instantaneously change the topography of volcanoes but also affect the feeding system by changing the lithostatic load. erosion and remobilization of volcanic material during inter-eruptive periods and longer quiescent periods build large volcaniclastic aprons that grade into other continental and marine sedimentary environments. fig. 1 example of correlation of unconformity bounded stratigraphic units (ubsu) and lithosomes in the context of the national cartography project (carg; sheets 374 roma, 387 albano laziale, 375 tivoli, 388 velletri). mailto:guido.giordano@uniroma3.it 2. methods in order to represent such complexity, within the framework of the italian geological map at the 1:50000 scale (carg project, ispra), the common lithostratigraphic approach to mapping of volcanic areas has been sided by other stratigraphic tools able to organize the stratigraphic successions based on the hierarchy of unconformities and on the morphology of the volcanic structures. formal units that can be used to this purpose are the unconformity bounded stratigraphic units (ubsu) and lithosomes. ubsu are able to represent objectively the extent and physical expression of unconformities, implicitly related to the extent and duration of the associated geological processes, e.g. an unconformity related to the change of global climate affecting the sea level versus a regional tectonic uplift versus a local caldera collapse (fig. 1). lithosomes represent individual edifices at various scales allowing to associate parts of the volcanic successions to specific sources and eruption styles. 4. results and discussion the experience of the last twenty years of mapping in volcanic areas of the italian volcanological community has established a sound approach for the representation of volcanic successions, which greatly enhances the role of geological maps as ground reference work for civil protection purposes in active areas and resource assessment in recent or extinct areas. at the same time, geological mapping of active volcanic areas is fundamental for hazard assessment. this is especially true at long-dormant volcano like vesuvius, ischia, campi flegrei, lipari, vulcano, pantelleria, colli albani, where most if not all of the objective data available rely on the rock-record. this makes it essential that geological mapping is made as quantitative as possible and that the relative data are stored in open-source databases. for example, outcrop and sample data on thickness, grain size, lithofacies, chemistry, mineralogy etc. would be of great use for extracting information necessary for modeling of several processes such as lava invasion and pyroclast dispersals in the atmosphere. in addition, 3d data should be made available, both as raw zdata and as thematic maps (fig. 2). in essence, while field-based studies are becoming less and less fashionable, the digital revolution opens up a significant opportunity where the quantitative reappraisal of fundamental mapping of volcanic units can and should become an essential tool for hazard studies. 218 giordano g. fig. 2 3d shaded relief, perspective reconstruction of the albano maar succession from surface and bore-hole data (from diano et al., 2010). the view is perspective and southeastward. green colours are the shaded relief (vertical exaggeration 3x, comprised between 100 m a.s.l. and 900 m a.s.l.). the brown-orange and red colours inside the continuous (certain) to dotted (extrapolated) line are thicknesses of the albano maar succession retrieved from outcrop and bore hole stratigraphies (vertical blue to pale blue lines). colli albani caldera albano maar extension of albano maar deposits colli albani ignimbrite plateau 219 acknowledgements this contribution briefly summarizes the work of and the discussion with many colleagues under the framework of the carg project. references branca s., coltelli m., groppelli g., lentini f. 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(1994) international stratigraphic guide a guide to stratigraphic classification, terminology, and procedure, second edition. boulder, colorado, the international union of geological sciences and the geological society of america, p. 214. volcano geology and mapping ms. received: may 9, 2018 final text received: may 23, 2018 220 untitled il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 late holocene relative sea level change in malta sara biolchi1,2, timothy gambin3, ritienne abela4, fabrizio antonioli5, stefano furlani6,1, marco anzidei7 & stefano devoto2 1 dipartimento di geoscienze, università degli studi di trieste, italy 2 dipartimento di scienze della terra, università degli studi di modena e reggio emilia, modena, italy 3 university of malta/aurora trust, malta 4 university of malta, malta 5 enea, casaccia, roma, italy 6 dipartimento di geografia “g. morandini”, università degli studi di padova, italy 7 ingv, roma, italy corresponding author: s. furlani <sfurlani73@gmail.com> abstract: biolchi s. et al., late-holocene relative sea level ch’ange in malta. (it issn 0349-3356, 2011) a multidisciplinary approach has been used to evaluate the late-holocene relative sea-level change in malta. published data, together with new coastal underwater observations of archaeological sites have been compared with predicted sea level curves, to evaluate the relative sea level change. riassunto: biolchi s. et al ., variazioni tardo-oloceniche del livello marino a malta. (it issn 0349-3356, 2011) le variazioni tardo-oloceniche di livello marino sull’isola di malta sono state studiate attraverso un approccio multidisciplinare. la comparazione tra una serie di nuove misure sulle quota di alcune strutture archeologiche costiere sommerse, l’utilizzo di dati pubblicati e le curve ottenute dai modelli hanno permesso di delineare una prima indicazione sulle variazioni di livello marino dell’isola. key words: sea level change, late-holocene, geoarchaeology, malta parole chiave: variazioni di livello marino, tardo-olocene, geoarcheologia, malta late-holocene relative sea level changes have been well-detailed along the mediterranean coasts. until now, few archaeological or geomorphological data have been considered to evaluate sea level changes along the maltese coast, although both the geomorphological evolution and the development of coastal settlements could provide useful information on the active tectonics (uplift or downlift, seismicity, etc). we aim at providing new data on coastal archaeological remains collected along the western and southern coast of malta and to discuss the relative late holocene tectonic rates. 1. study area malta lies in the sicily channel, about 200 km south of the convergent segment of the europeafrica plate boundary. the sicily channel has been affected, during neogene–quaternary (finetti, 1984; dart et al., 1993), by continental rifting which produced extensive structures, such as the pantelleria, malta and linosa tectonic depressions, controlled by nw-directed subvertical normal faults (fig. 1). the most active period of extension on both fault trends occurred during the plio-quaternary (jongsma et al. 1985). the maltese graben system is characterized by two intersecting fault trends. to the sw of malta, the 100 km wide nw-se-trending pantelleria rift occur (reuther & eisbacher 1985). it is dissected by the two important ene-wsw trending graben: the north gozo and north malta graben. the graben transects mesozoic to tertiary shallow marine and pelagic limestones. it has also been responsible for the major tectonic and geomorphological development of the maltese islands (illies, 1981). the stratigraphic succession, characterized by shallow marine deposits, spanning in time from upper oligocene to upper miocene (various authors, 1993). the studied sites are located on globigerina limestone. 2. data we studied two archaeological structures, the first at st. george’s bay, at birzebbugia and the latter next to manoel island, at the valletta harbour (fig. 1). 1) the birzebbugia archaeological site provides remains of activities related to the coastal zone, during the bronze age (zammit, 1928; abela, 1999). it provides two types of archaeological remains. the first type are bronze age pits (35002900 bp, fig. 2), located close to the shoreline on 20 22 21 the globigerina limestone platform, which are partially submerged. they were dated using pottery discovered in an archaeological site close to the coast. they were probably used as heats, as a red coat has been surveyed at the edge of the structures. the altitude of the lowest pit is -0.9 m and it represents the upper limit of sea level in the studied period, considering that they had to stay surely always above the sea. the second type are prehistoric cart tracks, completely submerged (abela, 1999). 2) at manoel island, submerged tanks, maybe roman in age, with an altitude ranging between 1.20 m at the bottom and -0.7 m at the top of the walls. they could be used to produce garum or purpura. 3. discussion on the island, archeological structures directly carved on rocky outcrops are very common, because of their high rock erodibility. the soft globigerina limestones outcrops along the southern and eastern sector of the island. archeological remains have been surveyed just along these coasts. anyway, observations carried out along the maltese coast recorded the presence of a number of nineteenth-century (victorian-age) swimming pools, usually architecturally welldefined. their position and their relative bad conservation can easily cause misunderstandings, insomuch as they can be confused with coastal archaeological remains. considering the submerged roman age tanks, despite their complex attribution, concerning both the age and the function, they seem to suggest that sea level was some tens of centimeters lower than the structure. on the contrary, the altitude of the lowest bronze age pit represents the upper limit of sea level in the studied period, considering that they had to stay surely always above the sea. no presence of mis 5.5 deposits have been surveyed, due (1) to the exposition of the island, that prevents the conservation of rocks and deposits, or (2) to the kind of bedrock easy to dismantle slightly submerged position of the tyrrenian deposits which deleted them. even if, at the moment, few data are available and better interpretations are required, the comparison of surveyed data and lambeck & purcell (2005) predicted curve, no late-holocene vertical displacement seem to be occurred. fig. 1 geodynamical setting of the maltese islands (modified after galea, 2007) and location of the two archaeological sites. inquadramento geodinamico dell’arcipelago maltese (modificato da galea, 2007) e ubicazione dei siti archeologici studiati. late-holocene relative sea level ch’ange in malta ... 22 ms. received: testo ricevuto il references abela r. (1999) – relative sea level change: a coastal vulnerability assessment of malta. unpublished thesis, university of malta, 217. dart c.j., bosence w.j. & mcclay k.r. (1993) stratigraphy and structure of the maltese graben system. j. geol. soc. lond. 150, 1153–1166. finetti i.r., (1984) geophysical study of the sicily channel rift zone. boll. geofis. teor. appl. 26, 3–28. galea p. (2007) seismic history of the maltese islands and considerations on seismic risk, annals of geophysics, 50 (6), 725-740. illies j.h. (1981) graben formation: the maltese islands – a case study, tectonophysics, 73, 151-168. jongsma d., woodside j.m., king g.c.p. & van hinte j.e. (1987) the medina wrench: a key to the kinematics of the central and eastern mediterranean over the past 5 ma, earth planet. sci. lett., 82, 87-106. lambeck k. & purcell a. (2005) – sea-level change in the mediterranean sea since the lgm: model predictions for tectonically stable areas. quaternary science reviews, 24, 1969-1988. reuther c.d. & eisbacher g.h. (1985) pantelleria rift crustal extension in a convergent intraplate setting, int. j. earth sci., 74 (3), 585-597. various authors (1993) geological map of the maltese islands. sheet 1 – malta – scale 1:25000, oil exploration directorate, office of the prime minister, malta. zammit t. (1928) prehistoric cart-tracks in malta, antiquity, 2 (5), 18-25. fig. 2, the pits at st. george’s bay, birzebbugia, s malta. le strutture archeologiche presso st. george’s bay, a birzebbugia, nella parte meridionale di malta.  s. biolchi et al. january 15, 2011 15 gennaio 2011 sess 1_160211.pub il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 sea level change in italy until 400 ka: comparing global sea level curves with observed data fabrizio antonioli enea casaccia, roma corresponding author: f. antonioli <fabrizio.antonioli@enea.it> abstract: antonioli f. sea level change in italy. (it issn 0394-3356, 2011) this paper report a review of the sea level change data published for italy for the last 400 ka and the markers used to constrain the curves. in particular it is underlined the importance to distinguish between global, local and predicted sea level curves. riassunto: antonioli f. sea level change in italy. (it issn 0394-3356, 2011) in questo lavoro viene effettuata una review di quanto recentemente pubblicato in italia in relazione alle variazioni di livello del mare a partire da 400 ka. viene distinta e spiegata la differenza tra curve globali, locali e predette. le prime basate sui dati provenienti da foraminiferi campionati sul fondo degli oceani e analizzati rispetto al rapporto isotopico dell'ossigeno. le seconde basate sui dati osservati datati e misurati su markers costieri, le ultime ricostruite attraverso complessi modelli geofisici. key words: relative sea level, italy parole chiave: livello relativo del mare, italia 1. introduction sea level change can be reconstructed from dated fossil coral reef terraces, and these data are complemented by a compilation of global sealevel estimates based on deep-sea oxygen isotope ratios at millennial-scale resolution or higher (specmap, imbrie et al., 1988). because of the lack of coral reefs in the mediterranean sea, results on late quaternary sea-level changes have been difficult to obtain in comparison with typical sites such as barbados) the huon peninsula, tahiti florida, and others. on the contrary the very low tidal range of italian seas offers a good opportunity to produce precise palaeo-sea level curves. sea level change along the italian coast during last 10 ka is the sum of eustatic, glacio-hydro-isostatic, and tectonic factors. the first is time-dependent while the latter two also vary with location (lambeck et al., 2004a). this means that at the same time slices the relative sea level (the sum of 3 different movements) should be different in different coastlines. for any palaeo reconstruction of an ancient coastline it is necessary to take into account all components. it is important to distinguish beteween global sea level curves (s.l.c.), local s.l.c. or predicted s.l.c., costrained using geophysical models. aim of the paper is to put together all sea level change data collected for italian seas to be compared with global sea level curves. 1.1. global s.l.c. global s.l.c. are generally constrained analyzing δ18o ratio on fossils foraminifera series, sampled on mud core of the ocean bottom. the δ18o ratio infact, show a direct correlation with sea level variations, and allows to calculate the sea level changes. this kind of curves do not take in account any isostatic component. the most recently published s.l.c. are reported in woalbreak et al. (2002) show that robust regressions can be established between relative sea-level data and benthic foraminifera oxygen isotopic ratios from the north atlantic and equatorial pacific ocean over the last climatic cycle. siddal et al. (2003) s.l.c. came from red sea 1.2. predicted and local s.l.c. to constrain a local s.l.c. it is necessary to collect and date fossils shells, biological markers, living at intertidal environment (i.e. dendropoma reef) or salt marsh lagoon are considered the best: maximum error bars infact is the mean annual tide. precose archaeological markers as fishtanks are also used (lambeck et al., 2004b) predicted slc are buitl from geopysical model (lambeck et al., 2004a) and take in consideration isostatic movements, calculation of tectonic ratea are based on predicted slc checked on stable area (antonioli et al., 2009) 11 13 12 f. antonioli 13 ms. received: testo ricevuto il 2. conclusion a general agreement for the holocene and mis 5.5, 7.1, 7.3, 7.5 italian aged fossil marine deposits or submerged speleothem are found (table 1). discrepancies in sea level observations on stable area with global data are found for mis 5.1-5.3, all that could be explained by the influences of glaciohydro-isostasy (potter et al., 2004). mis 3 are not preserved in cores as marine facies. the first two rows of table 1 shows the differences in isostasy for the same time slice in different stable coastal areas references amorosi a., colalongo m.l., pasini g., preti d. (1999) sedimentary response to late quaternary sea-level changes in the romagna coastal plain (n. italy). sedimentology, 46, 99–121. amorosi a., colalongo m.l., fiorini f., fusco f., pasini g., vaiani s.c., & sarti g. (2004) palaeogeographic and palaeoclimatic evolution of the po plain from 150-ky core records. global and planetary change, 40, 55–78. antonioli f., ferranti l., fontana a., amorosi a.m., bondesan a., braitenberg c., dutton a., fontolan g., furlani s., lambeck k., mastronuzzi g., monaco c., spada g., stocchi p. (2009) holocene relative sea-level changes and vertical movements along the italian coastline. quaternary international 221, 37-51. antonioli f., bard e., silenzi s., potter e. k., improta s. (2004) 215 kyr history of sea level based on submerged speleothems. global and planetary change, 43, 57-78. bard e., antonioli f., silenzi s. (2002) sea-level during the penultimate interglacial period based on submerged stalagmite from argentarola cave (italy). earth and planetary science letters 196/3-4, 135146. belluomini g., caldara m., casini c., cerasoli m., manfra l., mastronuzzi g., palmentola g., sanso p., tuccimei p.,vesica p.l. (2002) the age of late pleistocene shorelines and tectonic activity of taranto area, southern italy. quaternary science reviews 21, 525 –547. carboni g., bergamin l., di bella l., esu d., pisegna e., antonioli f., verrubbi v., (2010 palaeoenvironmental reconstruction of late quaternary foraminifera and molluscs from the enea borehole (versilian plain, tuscany, italy), quaternary research, 74, 265-276 dorale j., p. onac b., fornós j., ginés j., ginés a., tuccimei p., david w. & peate d. (2010) sea-level highstand 81,000 years ago in mallorca, science, 327, 860-863. dutton a., antonioli f., bard e., m. esat t., lambeck k, mcculloch m. (2009) phasing and amplitude of sea level and climate change during the penultimate interglacial. nature geosciences, 355-359. doi: 10.1038/ngeo470. ferranti l., et al. (2006) markers of the last interglacial sea level highstand along the coast of italy: tectonic implications. quaternary international 145146, 30-54. iannace a., romano p., santangelo n., santo a., tuccimei p. (2001) the ois 5c along licosa cape promontory (campania region, southern italy): morphostratigraphy and u/th dating. z. geomorph. n.f. 45 3, 307-319. iannace a., romano p., tuccimei p. (2003) u/th dating and geochenmistry of carbonate concretions associated with upper pleistocene fossils shorelines of the sorrento peninsula (conca dei marini, southern italy). il quaternario 16 bis, 38-49. imbrie j., hays j.d., martinson d.g., mcintyre a., mix a.c., morley j.j., pisias n.g., prell w.l. & shackleton n.j. (1984) the orbital theory of pleistocene climate: support from a revised chronology of the marine d18o record. in: a.l. berger et al. (eds), milankovitch and climate, part 1, reidel pub. co, 269-305. lambeck k., antonioli f., purcell a. & silenzi s. (2004a) sea level change along the italian coast for the past 10,000 yrs. quat. science revue. 23, 15671598. lambeck k., anzidei m., antonioli f., benini a. & esposito a. (2004b) sea level in roman time in the central mediterranean and implications for modern sea level rise. earth and planetary science letter. lambeck k, antonioli f., anzidei m., ferranti l., leoni g., scicchitano g. & silenzi s. (2011, in print) sea level change along italian coast during holocene and a proiection for the future. journal of quaternary international. potter e. k., lambeck k. (2004) reconciliation of sea-level observations in the western north atlantic during the last glacial cycle. earth and planetary science letters 217, 171-181. riccio a., riggio f., romano p. (2001) sea level fluctuations during oxygen isotope stage 5: new data from fossil shorelines in the sorrento peninsula (southern italy). z. geomorph. n. f. 451, 121-137. siddall m., rohling e. j., almogi-labin a., hemleben ch., meischner d., schmelzer i., (2003) sea level fluctuations during the last glacial cycle. nature 423, 853-858. waelbroeck c., labeyrie l., michel e., duplessy j.c., lambeck k., mcmanus j.f., balbon e., labracherie, m. (2002) sea-level and deep water temperature changes derived from benthic foraminifera isotopic records. quaternary science reviews 21, 295-305. sea level change in italy. january 14, 2011 14 gennaio 2011 amq abs capraro et al saccom 173-175.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 173 175 the 10be record as a proxy of paleomagnetic reversals and excursions: a mediterranean perspective luca capraro 1, patrizia ferretti 2, patrizia macrì 3, daniele scarponi 4, eliana fornaciari 1, feng xian 5, weijian zhou 5, xianghui kong 5, vanessa boschi 6 1 dipartimento di geoscienze, university of padova, padova, italy 2 cnr-idpa, mestre (venezia), italy 3 istituto nazionale di geofisica e vulcanologia, roma, italy 4 dipartimento di scienze biologiche, geologiche e ambientali, university of bologna, bologna, italy 5 state key laboratory of loess and quaternary geology, institute of earth environment, xi’an, china corresponding author: l. capraro <luca.capraro@unipd.it> abstract: the 10be/9be ratio is acknowledged as an effective tool for establishing the stratigraphic position of paleomagnetic excursions. still, our data suggest that, in particular depositional settings, the interplay between climate, sedimentation and oceanography may jeopardize a realistic depiction of the natural 10be/9be record. keywords: lower/middle pleistocene, central mediterranean, stratigraphy, paleomagnetism, 10be/9be 1. introduction the concentration of 10be atoms adsorbed on sediment particles is measured for tracking major geomagnetic reversals and events, whenever magnetic properties are poor and/or conventional palaeomagnetic analyses yield ambiguous results. this approach relies on both the assumptions that 1) the production rate of 10be in the atmosphere mainly depends on the strength of the earth’s magnetic field, and 2) the 10be generated in the atmosphere is rapidly conveyed to the earth’s surface and locked into sediments. however, the study of marine successions demonstrates that 10be record and palaeomagnetic events are mostly asynchronous (valet et al., 2014). in addition, the period of low intensity of the earth magnetic field associated to geomagnetic reversals, during which an overproduction of cosmogenic 10be is believed to occur, lasts significantly longer than the polarity switch itself (raisbeck et al., 2006). accordingly, there is no independent verification that a given 10be peak marks the exact stratigraphic position of the associated polarity switch, as it may have been generated at any time during the period of intensity low. to our knowledge, the only record reporting on a perfect synchronicity between the 10be and palaeomagnetic signals at the m–b reversal is that of valet et al. (2014), reconstructed in the equatorial indian ocean from a deep–sea sediment core virtually void of terrigenous influxes. in contrast, stratigraphic successions affected by a significant terrigenous input show that the 10be peak lags significantly behind the m–b boundary (e.g., suganuma et al., 2010). according to the interpretation given by suganuma et al. (2010), the 10be peak would point to the correct stratigraphic position (and age) of the reversal, while the geomagnetic signal would be “frozen” at a lower stratigraphic position, well below the sediment surface, in response to lock–in processes. mechanisms that control the flow of cosmogenic 10be particles to the earth surface and, more significantly, their transfer to the seafloor are still ambiguous. we may reasonably assume that the deposition of cosmogenic 10be in ice caps and loess deposits results from the instantaneous “freezing” of the atmospheric signal, although 10be deposition is known to respond to numerous environmental and climatic factors, such as the regional precipitation rates and regimes (e.g., mchargue & damon, 1991; raisbeck et al., 2006). when dealing with marine terrigenous successions, further levels of uncertainty should be added in order to account for the much more complex arrangement of the marine sedimentary system (e.g., brown et al., 1987, 1988; yiou et al., 1988; simon et al., 2017). 2. material and methods we reconstructed a continuous 10be/9be record straddling the m-b reversal for the valle di manche (vdm) section (calabria, southern italy) via the analysis of 68 sedimentary samples collected with an average resolution of ca. 9 cm, which results in a ca. 0.35 kyr resolution according to our age model (capraro et al., 2017). samples were prepared at the university of xi’an, china, according to the procedures reported by zhou et al. (2007), with minor modifications accounting for the difference between loess and marine sediments. beo measurements were performed using the 3-mv accelerator mass spectrometer (ams) at the xi’an ams center, ieecas. test chemistry blank ratios are very small, in the order of 1 ×10-14. https://doi.org/10.26382/aiqua.2018.aiquaconference 3. results our results compare very well with the high– resolution record of 10be and 9be reconstructed for the coeval montalbano jonico (mj) section (basilicata, southern italy; simon et al., 2016), where a conventional palaeomagnetic record of the m-b reversal cannot be achieved (sagnotti et al., 2010). the 9be and 10be concentrations measured at vdm are ca. four times those found at mj. the excess of 9be probably depends on the different primary sources of the terrigenous fraction, these being crystalline rocks from the sila massif at vdm and young sediments from the uplifting apennines at mj. in addition, the estimated sediment accumulation rates are significantly higher at mj, suggesting that, at vdm, the influx of 9be-free material was smaller. probably, the lower sedimentation rates at vdm also account for the higher background concentrations of 10be. at vdm, a prominent 9be spike is centered in correspondence to the “pitagora ash” (capraro et al., 2017), similarly to what documented at mj for the v3 and v4 tephra (simon et al., 2016). most likely, emplacement of the “pitagora ash” provided a massive injection into the water column of highly soluble 9be, which is very abundant in mantle sources (e.g., baroni et al., 2011). 4. discussion and conclusions our record does not provide a complete documentation across the mis 19–mis 18 transition, where 10be concentration attains a relevant peak that correlates almost perfectly to that recognized at mj at ca. 775 ka, which simon et al. (2016) interpret as the geochemical signature of the m-b reversal. this interpretation is at odds with that accomplished at vdm, where the palaeomagnetic record provides unquestionable evidence that the m-b reversal occurs in the midst of full mis 19 (ca. 787 ka according to our age model; macrì et al., 2018). at vdm, 10be concentrations peak ca. 3.5 m above the m-b reversal, i.e. ca. 12 kyr later than the geomagnetic event. this delay is grossly in agreement with that calculated by for many open-ocean records straddling the m–b reversal, where the effects of lock–in processes are invoked (suganuma et al., 2010). however, the high sediment accumulation rates at vdm made the impact of lock-in processes virtually negligible, if any. instead, our results suggest that, in particular settings prone to clastic sedimentation, the m-b reversal may actually predate the deposition of the 10be peak by ca. 10 kyr, possibly in response to the complex dynamics of both climate, ocean circulation and sedimentary system. acknowledgements this research was funded by the university of padova (progetto di ateneo 2010 and dor/ex-60% to l. capraro). references baroni m., bard e., petit j.r., magnan o., bourlès d.l. (2011) volcanic and solar activity, and atmospheric circulation influences on cosmogenic 10be fallout at vostok and concordia (antarctica) over the last 60 years. geochimica et cosmochimica acta, 75, 7132-7145. brown l. (1987) 10be as a tracer of erosion and sediment transport. chemical geology, 65, 189-196. brown l., pavich m.j., hickman r.e., klein j., middleton r. (1988) erosion of the eastern united states observed with 10be. earth surface processes and landforms, 13, 441-457. capraro l., macrì p., scarponi d., rio d. (2015) the lower to middle pleistocene valle di manche section (calabria, southern italy): state of the art and current advances. quaternary international, 383, 36-46. capraro l., ferretti p., macrì p., scarponi d., tateo f., fornaciari e., bellini g., dalan g. (2017) the valle di manche section (calabria, southern italy): a high resolution record of the early-middle pleistocene transition (mis 21-mis 19) in the central mediterranean. quaternary science reviews, 165, 31-48. macrì p., capraro l., ferretti p., scarponi d. (2018) a high-resolution record of the matuyama-brunhes transition from the mediterranean region: the valle di manche section (calabria, southern italy). physics of the earth and planetary interiors, 278, 1-15. mchargue l.r., damon p.e. (1991) the global beryllium 10 cycle. review of geophysics, 29, 141-158. raisbeck g.m., yiou f., cattani o., jouzel j. (2006) 10be evidence for the matuyama–brunhes geomagnetic reversal in the epica dome c ice core. nature, 444, 82-84. sagnotti l., cascella a., ciaranfi n., macrì p., maiorano p., marino m., taddeucci j. (2010) rock magnetism and palaeomagnetism of the montalbano jonico section (italy): evidence for late diagenetic growth of greigite and implications for magnetostratigraphy. geophysics journal international, 180, 1049-1066. simon q., bourlès d.l., bassinot f., nomade s., marino m., ciaranfi n., girone a., maiorano p., thouveny n., choy s., dewilde f., scao v., isguder g., blamart d. (2016) authigenic 10be/9be ratio signature of the matuyama-brunhes boundary in the montalbano jonico marine succession. earth and planetary science letters, 460, 255-267. simon q., thouveny n., bourlès d., nuttin l., hillairemarcel c. (2017) authigenic 10be/9be ratios and 10be-fluxes (230thxs-normalized) in central baffin bay sediments during the last glacial cycle: paleoenvironmental implications. quaternary science reviews, 2016, 140, 142-162. suganuma y., yokoyama y., yamazaki t., kawamura k., chorng-shern h., matsuzaki h. (2010) 10be evidence for delayed acquisition of remanent magnetization in marine sediments: implication for a new age for the matuyama-brunhes boundary. earth and planetary science letters, 296, 443450. valet j.p., bassinot f., bouilloux a., bourlès d., nomade s., guillou v., lopes f., thouveny n., 174 capraro l. et al. dewilde f. (2014) geomagnetic, cosmogenic and climatic changes across the last geomagnetic reversal from equatorial indian ocean sediments. earth and planetary science letters, 397, 67-79. you c.f., lee t., brown l., shen j.j., chen j.c. (1988) 10be study of rapid erosion in taiwan. geochimica et cosmochimica acta, 52, 2687-2691. zhou w.j., lu x.f., wu z.k., zhao w.n., huang c.h., li l.l., cheng p. (2007) new results on xi'anams and sample preparation systems at xi'anams center. nuclear instruments and methods in physics research b, 262, 135-42. 175 the 10be record as a proxy of paleomagnetic reversals and excursions: …. ms. received: may 7, 2018 final text received: may 74, 2018 176 available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 31 34 characteristics and potential application of holocene tidal inlets in the northern adriatic shelf (italy) livio ronchi 1 , alessandro fontana 1 , annamaria correggiari 2 1 dipartimento di geoscienze, università di padova, padova, italy 2 cnr-ismar istituto scienze marine, bologna, italy corresponding author: l. ronchi <livio.ronchi@gmail.com> abstract: in the last decades a series of offshore seismic and stratigraphic surveys revealed the presence of several infilled palaeo tidal inlets which punctuate the subsoil of the northern adriatic shelf. the morphologic, morphometric and sedimentary characteristics of these landforms constitute remarkable database for the reconstruction of palaeo coastline positions and to constrain the post-lgm sealevel rise, especially during the beginning of the holocene period. this work provides a first overview on the significance of the adriatic tidal inlets and their response to the interplay between upstream and downstream controls. keywords: holocene, sea-level rise, palaeo tidal inlets 1. introduction the constant adjustment and refining of the models predicting past sea-level position necessitate a continuous improvement and widening of sea-level indicators databases, which are essential for the calibration of the geophysical models (cf. vacchi et al., 2016; roy & peltier, 2018; stocchi et al., 2018). the peculiar low gradient (~0.4‰) that characterises the northern adriatic shelf made it extremely sensible to the eustatic variations, as even small increments of the sea level would have caused the drowning of large areas of the shelf. therefore, the transgressive record of the northern adriatic potentially represents an ideal environment for the reconstruction of a detailed post-lgm relativesea-level rise curve. the configuration of the northern adriatic shelf promoted the deposition of relatively thin layers of transgressive deposits which were dismantled after their drowning due to the wave effect of the rising sea (cattaneo & steel, 2003; fig. 1). thus, one of the few available indicators is represented by the tidal inlets, as their depth promoted their conservation within the stratigraphic record. these relict landforms could represent privileged spots for reconstructing timing and modes of the last marine transgression, before 7.5 ka bp, when the rate of sea-level rise was fast, since they are one of the few available, and sometimes almost continuous, sedimentary record of that period. this work offers a preliminary analysis of the tidal inlets on the scale of the whole northern adriatic and, in particular, it focuses on their evolution and significance in a sea-level and coastline reconstruction perspective. 2. material and methods the entire northern adriatic area has been investigated with more than 1000 chirp profiles (compressed high intensity radar pulse), for a total length of more than 12,300 km. all the chirp profiles analysed in this work were collected during the oceanographic campaigns named cm92, cm95, ve04, ve05, ri09, nad12 and asci14, which were organized by the cnr-ismar institute of bologna. these seismic lines were acquired in water depths ranging from -10 and -45 m mean sea level (msl). the collected data have a vertical resolution in the order of ca. 50 cm. along with the seismic data, several cores were analysed in order to provide ground truth for the interpretation and to obtain radiocarbon dates and micropalaeontological data. the available literature provided several additional sedimentary, palaeontological and chronological constrains that were integrated in our analysis (cf. correggiari et al., 1996; trincardi & argnani, 2001; trincardi et al., 2011, storms et al., 2008; moscon et al., 2015). 3. results more than 100 points with evidence of past tidal inlets were recognized on the italian side of the northern adriatic shelf (fig. 1). the morphometric characteristics and stratigraphic positions of all these landforms were stored in a database. the analysed tidal inlets show a wide range of dimensions: the thickness of their infilling spans from few to nearly 20 metres, their length can reach ca. 5 km, but normally its smaller than 1 km and their width can reach up to 400 m. a complete morphometric characterization is not possible for all the analysed features, as most of them were intercepted only by one or few chirp lines, but at least in two cases, which are being studied in detail, we have enough data to produce a detailed reconstruction of the palaeotopography of the inlets (fig. 2). the analysis of the position of the upper portion of all the tidal inlets indicate the presence of a clustering at the level of the entire northern adriatic https://doi.org/10.26382/aiqua.2018.aiquaconference shelf, with several cases localized at ca. -13 m, -24 m, 27 m and in the range between -30 and -34 m msl. 4. discussion 4.1 transgressive tidal inlet evolution in order to produce palaeo-environment reconstructions it is necessary to clearly understand the evolution of these landforms. in the study area, modern analogous systems are available for comparison purposes, as the conditions of sea-level rise rate and geometry of the continental shelf are not available in the present. the presence of groups of palaeo tidal inlets at clustered depths suggests the recurrent arising of conditions suitable for the development of lagoon-barrier complexes. these conditions may have different origin and controls. for example, climatic oscillations may have induced a temporary and general decreasing of the sea-level rise rate on a global or basin scale. these conditions have to be evaluated also in the framework of the palaeogeography and palaeoenvironmental evolution of the different areas, as the growing or waning of a lagoon complex may have been the result of a localized upstream river shifting. except for few cases (cf. storms et al., 2008, moscon et al., 2015), the analysis of the chirps highlighted the common absence of preserved barrier complexes. these landforms were usually erased along with the backbarrier basins after the overstepping of the lagoon system. the obliteration of these features from the stratigraphic record enhance the value of the tidal inlets, which, with their depth and infilling record, stand as one of the only witnesses of the post-lgm transgression in this area. it is likely that during a marine transgressive phase, tidal inlets are subjected to a rapid evolution due to the continuous forcing exerted by the rising sea. no large mobility of the inlet is expected in such dynamic environment, as the data collected so far suggest that the scouring and infilling phases of these landforms took place in the time frame of few centuries (ronchi et al., submitted). the sea-level rise recurrently induced the landward migration of backbarrier areas, which lead to periodic phases of tidal inlets abandonment and barrier complexes demolition. in particular, the abandonment and 32 fig. 1 geological map of the northern adriatic area. the red rectangles indicate the areas where the tidal inlets are mainly concentrated. the red star indicates the position of the inlet reconstructed in fig. 2. ronchi l. et al. 33 submersion of an older lagoon in favour of a new inner lagoon would led to the deactivation of the tidal inlets and their consequent infilling guided by the progressive decrease of the tidal flow running through the inlet. 4.2 sea-level rise reconstruction in the light of the previous reconstruction, it must be noticed that any radiocarbon date obtained on organic samples from the filling of an inlet, must be accurately evaluated in order to understand its real meaning. the easiest case would be to obtain a date from a lateral accretion bar within the infilling, considering that the lateral migration of an inlet would take place before the beginning of its deactivation. this kind of date would be indicative for reconstructing the sea-level rise curve, supposing to know the exact depth of the tidal inlet top. unfortunately, the analysed transgressive inlets are usually filled by draping layers as time and equilibrium conditions for the lateral or landward migration of these landforms were usually lacking. in this second case, in order to obtain an age for the peak of activity, the sample must be collected from the very bottom of the infilling sequence, therefore before the deactivation and blanketing of the inlet began. this evaluation must also take into account the provenance of the organic sample and the possible origin from a previous deposit eroded in the upstream catchment of the lagoon or during the scouring of the tidal inlet. 4.3 palaeo coastline reconstruction the presence of tidal inlets is also a clear indicator for the reconstruction of the position of the coastline. by their subdivision in clusters of depth it is possible to delineate the seaward limits of a series of barrier-lagoon complexes along palaeo coasts. the presence of more than one tidal inlets at the same depth and within the same region may allow to delineate, with a good approximation, the coastline position over a wide area. such reconstruction needs a careful evaluation of the stratigraphy of the area in order to correctly attribute different tidal inlets to the same coastline as the top of these landforms are usually subjected to the ravinement erosion, which can affect up to 6 m of their upper stratigraphy (cf. rieu et al., 2005). the internal geometry of the infilling of most of the analyzed tidal inlets suggest that the upper portion removal was usually small in the adriatic area, and probably never greater than 2 m. holocene tidal inlets of the northern adriatic shelf fig. 2 upper portion: example of tidal inlet cross section visible in a chirp profile. lower portion: reconstruction of the planform of the tidal inlet. the black line indicates the position of the chirp profile. after ronchi et al. (submitted). 5. conclusion the analysis of the palaeo tidal inlets constitutes an innovative tool for the reconstruction of the palaeogeography, palaeoenvironment and sea-level rise history of the post-lgm transgression. the case of the northern adriatic represents a perfect test area for this method. more than 100 specimens of palaeo tidal inlets were recognized and analysed. this allowed the preliminary definition of at least four main phases of relative decrease in the sea-level rise rate. the interpretation of the obtained data must be preceded by a site-specific stratigraphic analysis in order to infer the correct palaeogeographic and chronologic information. references amorosi a., pacifico a., rossi v., ruberti d. (2012) late quaternary incision and deposition in an active volcanic setting: the volturno valley fill, southern italy. sedimentary geology, 242, 307-320. cattaneo a., steel r.j. (2003) transgressive deposits: a review of their variability. earth-science reviews, 62, 187-228. correggiari a., roveri m., trincardi f. (1996) late pleistocene and holocene evolution of the north adriatic sea. il quaternario italian journal of quaternary sciences, 9, 697-704. moscon g., correggiari a., stefani c., fontana a., remia a. (2015) very-high resolution analysis of a transgressive deposit in the northern adriatic sea (italy). alpine and mediterranean quaternary 28, 121-129. rieu r., van heteren s., van der spek a. j. f., de boer p.l. (2005) development and preservation of a mid-holocene tidal-channel network offshore the western netherlands. journal of sedimentary research, 75, 409-419. ronchi l., fontana a., correggiari a., asioli a. (submitted) late quaternary incised and infilled landforms in the shelf of the northern adriatic sea (italy). marine geology. roy k., peltier w.r. (2018) relative sea level in the western mediterranean basin: a regional test of the ice-7g_na (vm7) model and a constraint on late holocene antarctic deglaciation. quaternary science reviews, 183, 76-87. stocchi p., vacchi m., lorscheid t., de boer b., simms a.r., van de wal r.s.w., vermeersen b.l.a., pappalardo m., rovere a. (2018) mis 5e relative sea-level changes in the mediterranean sea: contribution of isostatic disequilibrium. quaternary science reviews, 185, 122-134. storms j.e.a., weltje g.j., terra g.j., cattaneo a., trincardi a. (2008) coastal dynamics under conditions of rapid sea-level rise: late pleistocene to early holocene evolution of barrier-lagoon systems on the northern adriatic shelf (italy). quaternary science reviews, 27, 1107-1123. trincardi f., argnani a. (2001) note illustrative della carta geologica d’italia alla scala 1:250,000 – foglio nl33-10 “ravenna”. ispra servizio geologico d’italia. trincardi f., argnani a., correggiari a. (2011) note illustrative della carta geologica d’italia alla scala 1:250,000 foglio nl33-7 “venezia”, ispra servizio geologico d’italia. vacchi m., marriner n., morhange c., spada g., fontana a., rovere a. (2016) multiproxy assessment of holocene relative sea-level changes in the western mediterranean: variability in the sea-level histories and redefinition of the isostatic signal. earth science reviews, 155, 172-197. 34 ronchi l. et al. ms. received: may 7, 2018 final text received: may 21, 2018 available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 93 97 palaeoenvironment and vegetation history in the central po plain (n-italy) between 33-30 ka cal bp under the impact of millennial climate change cesare ravazzi 1 , lorena garozzo 1 , massimiliano deaddis 1,2 , mattia de amicis 3 , mauro marchetti 4 , roberta pini 1 , giovanni vezzoli 3 , andrea zanchi 3 1 laboratory of palynology and palaeoecology, cnr idpa, milano, italy 2 cfp san giuseppe cooperativa sociale onlus, lodi, italy 3 dept. of environmental and earth sciences, university of milano bicocca, milano, italy 4 dept. of education and humanities, university of modena and reggio emilia, reggio emilia, italy corresponding author: c. ravazzi <cesare.ravazzi@idpa.cnr.it> abstract: the last glaciation environmental history of the po plain (northern italy) is still poorly known. here we present a multiproxy record from a compressed peat dated 33-30 ka cal bp, underlying the last glacial maximum fluvio-glacial belt in the adda river catchment. slow river dynamics and subsurface water saturation granted stable surfaces supporting mixed pine-birch forests, including open wetlands marshes and swamps and open drylands, with juniper bushes, connected to sandy river bars. fire phases favoured birch but decreased arboreal pollen, although open lands did not expand. we discuss relationships with millennial climate variability between gi-6 and gs-5.1. keywords: last glaciation, po plain, boreal forest, alluvial plain, radiocarbon dating, millennial climate variability 1. introduction the late pleistocene geological and environmental history of the central po plain in northern italy is driven by phases of aggradation by large alluvial bodies, mostly originating at the pre-alpine margin from the valley outlets of the two major alpine rivers (i.e. adda river, see fig. 1, and oglio river). actually, as far as the adda and oglio glaciers occupied their piedmont end moraine systems, about 27 to 21-18 ka cal bp, several outwash rivers were actively building up a coalescent sandar belt even reaching the axial sector of the po plain (ravazzi et al., 2012), palaeoenvironments being dramatically influenced by fast channel dynamics and persisting high water discharge. here we present a high-resolution palaeobotanical research and coupled alluvial stratigraphy carried out in the underlying deposits dated to late mis 3 and thus shortly preceding the last glacial maximum (lgm) peak aggradation events, depicting a comparatively different environmental framework for the distal adda plain, with forested stable surfaces, millennial-standing pools and low sedimentation rate, suggesting a low-gradient plain. thanks to a robust ams 14 c chronology, we examine the effects of the pronounced millennial palaeoclimatic variability which affected northern italy in late mis 3. 2. material and methods a 18 m-thick sediment sequence outcropping at casaletto ceredano (coord. wgs84 45°18'49.75"n, 9°37'21.86"e; province of cremona, 65 m asl, fig. 1), along the scarp of the entrenched postglacial adda river valley, shows the depositional history between > 40 and the local end of the lgm aggradation surface. the complete sections are shown in fig. 2; the study focused on a 40 cm-thick compressed peat and silty peat, sampled through a 50 cm-long metal box. palynology (27 samples), macroscopic charcoal (48) and geochemistry (81) were analyzed. pollen and other microbiological particles were extracted by chemical treatments (acid treatments, koh), microfiltrations and acetolysis, and identified at the optical microscope, reaching a minimum pollen sum of 500 pollen grains. macrocharcoal fragments between 125 µm 1 mm and > 1 mm length were wet-sieved and counted under a stereomicroscope. four samples of wood and charcoal fragments were radiocarbon-dated at the angstrom lab., uppsala university. calibration was carried out using calib version 7.0.4 with the intcal13 calibration curve (reimer et al., 2013). an age-depth model was built up with the bayesian technique in oxcal package. 3. results 3.1. chronology the dated wood and charcoal originate from two sections exposing the compressed peat stratigraphy which could be visually correlated at cm-detail. the composite section yielded ages spanning a nice sequence (tab. 1) between 25975 ±450 and 32950 ±1070 14 c a bp (median calibrated ages 30144 37150 cal a bp). we selected in situ wood and large wood charcoal fragments (unweathered compressed wood from tree stems and cm-thick wood charcoal) in order to minimize the effects of either contamination or rielaboration. the latter https://doi.org/10.26382/aiqua.2018.aiquaconference taphonomic process is a cause of age bias in drift peat imbedded in alluvial and glacial deposits. the availability of datable wood tissue from tree stems obviously depends on tree occurrence in contemporary vegetation, a circumstance which favourably compares with the forest persistence in n-italy throughout the last glaciation. a posterior analysis of a bayesian age/depth model designed in software oxcal also supports the reliability of the obtained age sequence between top and base of the compressed peat layer, spanning about three millennia between (29172 -2σ range) 30144 and 33427 (34791 -2σ range) cal a bp. 3.2. pollen, charcoal stratigraphy and vegetation history we obtained a pollen and charcoal record with an average sample resolution (133 and 65 years respectively) suitable to detect centennial-scale secondary ecological successions as well as the effects of millennial climate events which characterized the late mis 3, although our detail is still not appropriate to check fire frequency. the vegetation history is clustered in the following pollen % phases (fig. 3, upper panel): cc01 (91-93 cm) before the onset of organic deposition, sandy sediments are characterized by moderate values of pine pollen (pinus sylvestris/mugo) accompanied by several herbs. low xerophytes (artemisia, ephedra, hippophaë, chenopodiaceae) mark open environments, such as sandy riverbeds. cc02 (93-97 cm) an organic soil rich in charcoal particles developed, recording higher pine pollen percentages (75-88%). the abundance of charcoal, along with cm-size fragments, suggests local fires affecting pine woodlands. indicators of local wetlands are still scanty. cc03 (97-101 cm) a sharp decrease in pine pollen abundance is coupled with increasing values of betula (birch) and the expansion of wetland and herb vegetation (cyperaceae, gramineae). the in situ development of a carex (sedge) fen is shown by the abundance of sedge roots. we infer a withdrawal of pine forests that had previously been affected by fires, while pioneer birches and terrestrial wetlands expanded, favored by increasing water table. cc04 (101-111 cm) pine pollen increases again (values around 70%), juniperus and other xerophytes expand. we reconstruct a rather open pine forest, including sporadic spruce, with open land occupied by juniperus and herbs. a sedge marsh persists locally, its 94 fig. 1 digital terrain model of part of the central po plain in northern italy showing the valley cut by the adda river into the alluvial fan system formed during the last glacial maximum (in dark grey). tributary rivers brembo and serio, as well as inactive post-lgm valleys and ancient oxbow basins are shown. the casaletto ceredano sections are outcropping on the eastern scarp delimiting the post-lgm adda valley. lo = lodi; bg = bergamo; cr = crema. ravazzi c. et al. 95 fluctuations depending on detrital supply. cc05 (111-117 cm) pine stillstand (70%), xerophytes, open vegetation and sedge fen developed (sedges roots are abundant in sediments). the local environment was more drained and partially oxygenated, favoring the activity of some fungi (glomus). last phase (117-119 cm) pine pollen declines and birch expands, as a consequence of a renewed phase of fires. the find of tree birch stems in these peat layers suggests that those trees settled in situ together with sedges (birch swamp). 4. discussion and conclusion the compressed peat deposit at casaletto ceredano formed in a long-lasting wetland occupied by a terrestrial marsh and finally by a swamp forest, subtly fed by silt from the adda river catchment. the radiocarbon sequence robustly points to the persistence of this regime for about three millennia. this requires an overall subsurface water saturation, favoured by a thingrained texture (silty sands), and excludes fast river dynamics and aggradation processes in the area, which would have implied an immediate wetland burial by an actively growing minerogenic plain surface. accordingly, sediment accumulation rate for the underlying minerogenic deposits (0.16 mm/a between 37.1 and 33.4 cal ka bp) is low compared to estimated lgm fluvio-glacial rates. compressed peat layers are common in the lower adda valley alluvial record (casaletto ceredano unit, see ravazzi et al., 2012), but so far dated to > 40 cal ka bp, thus accumulation rates could not be measured yet. an impressive amount of late pleistocene mammal remains, including one neanderthal frontal bone, have been rielaborated, mostly from the casaletto ceredano unit and heteropic units formed in adjacent river catchments, and accumulated downstream in secondary deposition (persico et al., 2015). recent downcutting provides field evidence of post-depositional deformation in these peat seams, suggesting that late pleistocene deformational events may be of importance for the paludification history of the area, e.g. through the development of microrelief and channel diversions. palaeobotanical analysis established that pine and birch forests persisted across the late mis 3 on stable surfaces in the lower adda valley, regardless to intervening millennial climate variability. edaphic and topographic factors and ecological disturbance changes are believed to have modulated the extent of open habitats (open drylands on sandy river channels and bars, treefig. 2 summary logs of sections exposed along the eastern scarp of the adda river valley at casaletto ceredano. compressed peat layer in dark brown. p = root casts marking exposed surfaces in sand layers. labels 1 and 2 show the position of petrographic samples for sediment provenance analysis. tab. 1 radiocarbon ages obtained on terrestrial plant remains from the casaletto ceredano sections. palaeoenvironments of the central po plain 33 30 ka cal bp 96 ravazzi c. et al. less wetlands depending on subsurface water saturation, fire avoiding wetland areas). still, climate variability may have acted as the ultimate factor driving the alluvial geo-ecological system. in fig. 3 (lower panel) we compare isotope and dust proxies from the ngrip core depicting stadial-interstadial sequence between 30 and 34 cal ka bp (rasmussen et al., 2014) with the arboreal pollen and xerophyte pollen % from casaletto ceredano, plotted against their own age-depth model, and propose a tentative correlation. notice that, in our record, fire phases marks enhanced forest phases (gi-6 and gi-5.2). birch expansion occurred at the end of fire phases, mirroring the typical succession of modern boreal forests (sannikov and goldammer, 1996), and also lead to a slight arboreal pollen decrease, although open land did not expand henceforth. stadial phases gs-6 and gs-5.2 might correlate to phases of higher water table, triggered by increased fluvio-glacial discharge. overall, during late mis 3 the central po plain remained under a cold temperate regional climate of middle boreal type (moen, 1999), with tjuly < 15°c, but well within the climatic woodland limits. quantitative climate reconstructions are planned as next research step. references moen a. (1999) national atlas of norway vegetation. norwegian mapping authority, honefoss, n., persico d., billia e.m.e., ravara s., sala b. (2015) the skull of stephanorhinus kirchbergensis (jäger, 1839) (mammalia, rhinocerontidae) from spinadesco (cremona, lombardia, northern italy): morphological analyses and taxonomical remarks an opportunity for revising the three other skulls from the po valley. quaternary science reviews, 109, 28-37. rasmussen s.o., bigler m., blockley s.p., blunier t., buchardt s.l., clausen h.b., cvijanovic i., dahljensen d., johnsen s.j., fischer h. et al. (2014) a stratigraphic framework for abrupt climatic changes during the last glacial period based on three synchronized greenland ice-core records: refining and extending the intimate event stratigraphy. quaternary science reviews, 106, 14-28. ravazzi c., deaddis m., de amicis m., marchetti m., vezzoli g., zanchi a. (2012) the last 40 ka evolution of the central po plain between the adda and serio rivers. géomorphologie: relief, processus, environment, 2, 131-154. reimer p.j, bard e., bayliss a., beck j. w., blackwell p.g., bronk ramsey c., buck c.e., cheng h., lawrence edwards r., friedrich m., grootes p.m. et al. (2013) intcal13 and marine13 radiocarbon age calibration curves 0–50,000 years cal bp. radiocarbon, 55 (4), 1869-1887. sannikov s.n., goldammer j.g. (1996) fire ecology of pine forests of northern eurasia. in (goldammer j.g. & furyaev v.v. , eds.) fire in ecosystems of boreal eurasia. forestry science, 48, 151-167. kluwer academic publishers, dordrecht. 97 palaeoenvironments of the central po plain 33 30 ka cal bp << <<< ------------ fig. 3 (upper panel) palaeobotanical proxies, pollen zonation and radiocarbon ages obtained from the compressed peat layer at casaletto ceredano, lower adda river valley, central po plain, plotted against stratigraphy. (lower panel) summary palaeobotanical proxies (arboreal pollen; sum of xerophytes i.e. artemisia, ephedra, chenopodiaceae, hippophaë; sieved charcoal) plotted against chronology and compared with isotope and dust proxies from the ngrip core. ms. received: may 4, 2018 final text received: may 16, 2018 98 amq abs valente et al tepro 243-246.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 243 246 karst sinkholes formation and spatial distribution: clues from the southern apennines (italy) ettore valente 1, alessandra ascione 1, nicoletta santangelo 1, antonio santo 2 1 dip. di scienze della terra, dell’ambiente e delle risorse (distar), università degli studi di napoli federico ii, napoli, italy 2 dip. di ingegneria civile, edile ed ambientale (dicea), università degli studi di napoli federico ii, napoli, italy corresponding author: e. valente <ettore.valente@unina.it> abstract: sinkholes that affect both carbonate rocks and alluvial plain deposits are widely distributed in the southern apennines. karst sinkholes, in particular, are generally clustered within high sinkhole concentration area (hsca). a geological and geomorphological study of some, selected hsca, has been carried out, aimed at constraining hypotheses on both factors that control sinkhole spatial distribution and causative mechanisms of karst collapses. based on independent evidence on the active tectonic framework and deep fluid rising in the hsca, karst sinkhole phenomena appear related the hypogenic karst controlled by the rise of acidic fluids along active faults. keywords: sinkholes, karst sinkholes, active faults, southern apennines 1. introduction the term sinkhole broadly indicates any mediumsized, sub-circular depression without considering its origin (beck, 1984). the same term is adopted for both karst related and anthropogenic collapses (santo et al., 2011; scotto di santolo et al., 2018). regarding karst sinkholes, a genetic classification has been recently proposed by gutierrez et al. (2008). karst sinkholes occur in the entire southern apennines, however they are densely distributed in specific areas labelled high sinkhole concentration area hsca, sensu santo et al. (2011). recent studies highlight the occurrence of some peculiar geological and geomorphological features in the hsca, such as the occurrence of active faults that are inferred as acting as pathways for the rise of deep fluids (santo et al., 2011, 2017). karst collapse sinkholes are also often associated with gas vents and mineral springs. we have carried out a study aimed at the characterisation of the main geological and geomorphological features of some of the hsca. selected areas are (from the nw to the se) the pratella area, the telese solopaca area and the contursi area (fig. 1). the investigated areas are characterised by the occurrence of mineral and/or thermal springs. furthermore, in all of the investigated areas deep fluid inputs are either testified by gas vents, or inferred from mineralogy and geochemistry of precipitated minerals (ascione et al., 2018; santo et al., unpublished data). we have combined geological and geomorphological investigations aimed at reconstructing local geological setting and at detecting evidence for active faulting in the study areas. the aim of our study is to constrain hypotheses on causative mechanisms of karst sinkhole formation and factors that control karst sinkhole spatial distribution. 2. material and methods the study areas are located in the axial portion of the southern apennines and include the telese solopaca and the contursi area already identified by santo et al. (2011). in addition, the pratella area has been investigated on the basis of the recent paper of ascione et al. (2018). detailed geological and geomorphological investigations have been carried out. the geological analysis was based on the combination of field surveys with stratigraphical data of both published and unpublished boreholes. the latter ones, in particular, provided useful constraints on the spatial distribution and features of both outcropping and buried quaternary deposits. the geomorphological investigation has been based on the analysis of detailed topographic maps (1:5000 scale technical map of the regione campania) and has been addressed to the recognition and mapping of fault controlled features such as fault scarps, triangular facets, river bends, wind gaps, water gaps, beheaded valleys, besides sinkholes. the latter have been classified as either karst collapse sinkholes or alluvial plain sinkholes. mineral, sulphurous and hot springs have been also mapped. mineralogical and geochemical data within study areas have been derived from the literature. all of such information has been plotted on a simplified geological map of the southern apennines, in which information on active and capable faults (derived from detailed, local scale, and the ithaca database, http:// sgi.isprambiente.it/geoportal/catalog/content/project/ ithaca.page) and epicentres of moderate to strong earthhttps://doi.org/10.26382/aiqua.2018.aiquaconference quakes has been included. locations of epicentres has been extracted from the parametric catalogue of italian earthquakes (rovida et al., 2016), with the exception of the 280 b.c., 346, 847, 1349, 1456 and 1805 earthquakes, whose locations are from galli & naso (2009). 3. results 3.1 pratella area the pratella area (box a in fig. 1) is located to the southwest of the matese ridge. the pratella area is characterised by carbonate hills, whose elevations range between 300 and 500 m a.s.l., which are dissected by the lete river valley. in the pratella area, the lete mineral spring is located. the carbonate hills of the pratella area are interposed between quaternary lacustrine deposits that crop out in the ciorlano area, to the north, and ailano area, to the south. quaternary lacustrine deposits in the areas of ailano and ciorlano form terraces that are dissected and eroded at variable degrees, whose elevation ranges between 230 and 280 m a.s.l. geological, geomorphological and stratigraphical data allowed the recognition of several extensional fault strands with evidence of activity in the late quaternary, with prevailing e-w and n-s orientations that affect both the carbonates and the alluvial deposits (ascione et al., 2018). karst sinkholes in the pratella area are clustered along the carbonate hills. they are mainly distributed along an e-w direction, and are aligned with some active fault strand. the lacustrine basins of ciorlano and ailano are characterised by several gas vents and diffuse gas emission. the spatial distribution of the gas vents and gas emissions shows alignments that are consistent with orientation of active faults (ascione et al., 2018). geochemical data point to strong co2 emission, which is among the highest gas emissions in non-volcanic 244 fig. 1 spatial distribution of sinkholes in the southern apennines plotted on a simplified geological map (modified from santo et al., 2011 and ascione et al., 2013). white boxes indicate hsca investigated in this study. a: pratella area; b: telese solopaca area; c: contursi area. valente e. et al. 245 areas in the world (ascione et al., 2018). isotopic analyses of c in the co2 suggest a crustal origin of the emitted gas, probably due to thermo-metamorphism of buried apulian carbonates triggered by buried magmatic bodies (ascione et al., 2018). 3.2. telese solopaca area the telese solopaca area (box b in fig. 1) is located to the north of the mt. camposauro massif. the latter consists of carbonate rocks and is bounded to the north by a wide piedmont area made up of slope and alluvial fan deposits interbedded with tephra layers. the calore river valley limits the camposauro northern slope and its piedmont to the north (amato et al., 2018). the solopaca village falls in this area, whereas the telese village is located at the base of mt. pugliano, an isolated carbonate hill located to the northeast of solopaca. amato et al. (2018) point to the occurrence of several normal faults with evidence of activity in the late quaternary. active fault strands affect the entire camposauro piedmont and the telese area, and are mainly e-w and ne-sw trending. sinkholes occur in the surrounding of both the solopaca and telese villages. sinkholes in the solopaca area affect the alluvial fan conglomerates. they are nesw aligned and placed close to some of the ne-sw trending active faults, while sinkholes in the telese area affect the top surface of mt. pugliano, and are also aligned with fault strands. here, thermal spring of telese and large travertine bodies also occur, with �13c isotopic values of the carbonates indicating a crustal contribution (santo et al., 2011; ascione et al., 2014). mineralogical and geochemical analyses of gypsum rich cursts/patina precipitated close to telese hot springs and inside the sinkholes have been carried out by santo et al. (2018). isotopic analyses of �34s and �18o indicate a deep origin of sulphate leading the authors to hypothesize the presence of a deep-seated sulphur source. 3.3. contursi area the contursi area (box c in fig. 1) is dominated by the ~1600 m high mt. marzano carbonate massif which is bounded, to the south, by san gregorio magno and buccino intramontane basins, filled by late quaternary fluvio-lacustrine deposits. several evidences of recent faulting have been identified in these area, resulting in few km long fault strands affecting both the mt. marzano and the adjoining intramontane basins (ascione et al., 2013). sinkholes have been identified along the carbonate southern slope of mt. marzano and related alluvial fans. in addition, sinkholes affect the top surface of mt. pruno close to contursi village. here, a thermal hot spring is also present. their distribution is consistent with some of the active fault strands recognized by ascione et al. (2013) and santo et al. (2011). santo et al. (unpublished data) carried out a detailed mineralogical investigation of limestones and related precipitates close to sinkhole and mineral spring. the author found isotopic composition of s and o compatible with a deep source. 4. discussion and conclusions karst sinkholes are widespread in the southern apennines, and in several instances are found close to active faults. in some cases, such as the pianelle sinkhole along the southern slope of mt. marzano, their formation is linked to seismic shaking related to high magnitude earthquakes (santo et al., 2011; unpublished data). independent mineralogical and geochemical evidence from the investigated hsca highlights the occurrence, in the surroundings of the karst sinkholes, of both co2 emissions and strongly weathered carbonate rocks associated with diffuse precipitation of sulphure-rich minerals (ascione et al., 2018; santo et al., unpublished data). gas vents are also found within or close to the hsca (ascione et al., 2018), even if their distribution is strongly controlled by the rock-type, being clustered where clayey rocks crop out. isotopic composition of both gas emission and precipitates point to a crustal origin of rising fluids, triggered by the presence of buried magmatic bodies (ascione et al., 2018; santo et al., unpublished data). overall scenario from the investigated hsca suggests that enhanced dissolution that originates karst sinkholes is triggered by the presence of acidic (co2 and/or h2s rich) fluids. clustering of karst sinkhole phenomena appears related with localised hypogene karst controlled by the rise of acidic fluids conveyed towards the surface by active faults. references amato v., aucelli p.p.c., cesarano m., filocamo f., leone n., petrosino p., rosskopf c.m., valente e., casciello e., giralt s., jicha b. (2018) geomorphic response to late quaternary tectonics in the axial portion of the southern apennines (italy): a case study from the calore river valley. earth surface processes and landforms. doi: 10.1002/esp.4390. ascione a., mazzoli s., petrosino p., valente e. (2013) a decoupled kinematic model for active normal faults: insights from the 1980, ms = 6.9 irpinia earthquake, southern italy. geological society of america bulletin, 125 (7-8), 1239-1259. ascione a., iannace a., imbriale p., santangelo n., santo a. (2014) tufa and travertines of southern italy: deep seated, fault related co2 as the key control in precipitation. terra nova, 26 (1), 1-13. ascione a., ciotoli g., bigi s., buscher j., mazzoli s., ruggiero l., sciarra a., tartarello m.c., valente e. (2018) assessing mantle versus crustal sources for non-volcanic degassing along fault zones in the actively extending southern apennines mountain belt (italy). geological society of america bulletin. doi:10.1130/b30814.1, in press. beck b.f. (1984) sinkholes, their geology, engineering and environmental impact. proceedings of the first multidisciplinary conference on sinkholes, orlando, fl. a.a. balkema publisher, rotterdam, netherlands, pp. 429. galli p., naso g.a. (2009) unmasking the 1349 earthquake source (southern italy): paleoseismological and archaeoseismological indications from the karst sinkholes formation and spatial distribution aquae iuliae fault. journal of structural geology. 31, 128-149. gutiérrez f., guerrero j., lucha p. (2008) a genetic classification of sinkholes illustrated from evaporite paleokarst exposure in spain. environmental geology, 53, 993-1006. rovida a., locati m., camassi r., lolli b., gasperini p. (2016) cpti15, the 2015 version of the parametric catalogue of italian earthquakes. istituto nazionale di geofisica e vulcanologia. doi: 10.6092/ingv.it-cpti15. santo a., ascione a., del prete s., di crescenzo g., santangelo n. (2011) collapse sinkholes distribution in the carbonate massifs of central and southern apennines. acta carsologica, 40, 95-112. santo a., budetta p., forte g., marino, e., pignalosa a. (2017) karst collapse susceptibility assessment: a case study on the amalfi coast (southern italy). geomorphology, 285, 247-259. santo a., santangelo n., balassone g., strauss h. (unpublished data) hypogene karst as the key agent of high sinkhole concentration areas (southern apennines, italy): mineralogical and geochemical constraints. earth surface processes and landforms, (submitted). scotto di santolo a., forte g., santo a. (2018) analysis of sinkhole triggering mechanisms in the hinterland of naples (southern italy). engineering geology, 237, 42-52. 246 valente e. et al. ms. received: april 28, 2018 final text received: may 16, 2018 amq abs pieruccini et al saccom 185-188.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, abstracts, aiqa 13-14/06/2018 florence, 185 188 seqs-datestra a database of terrestrial quaternary stratigraphical sites of europe: inqua funded international focus group 1620f saccom pierluigi pieruccini 1, guzel danukalova 2, markus fiebig 3 1 dipartimento di scienze della terra, università di torino, torino, italy 2 institute of geology of the ufimian, ufa, russia 3 dep. civil engineering & natural hazards, inst. of applied geology, university of natural resources and life sciences, wien, austria corresponding author: p. pieruccini <pierluigi.pieruccini@unito.it> abstract: seqs for the 2016-2019 intercongress period aims to build a database of quaternary terrestrial european stratigraphic sites (datestra). datestra follows the need for a concise, informative and easy to use system to share as many information as possible about the most important quaternary sites across europe. the main goal is to create a database that summarize the litho-, bio-, pedo-, morpho and chrono-stratigraphical data becoming a tool for cross-border correlations of the main quaternary subdivisions in europe, combining existing knowledge and expertise of regional specialists. the main outcome expected is a database shared and made available to all the quaternary audience on open gis based web platforms to give to the wider audience as possible, also at informative level, the chance to have an overview of the european terrestrial quaternary setting. at the next inqua congress (2019 dublin, ireland), datestra ongoing works will be presented in a joint session with seqs. keywords: quaternary, stratigraphy, key-sites, geographic database, europe 1. introduction for the 2016-2019 inqua intercongress period, seqs (inqua section on european quaternary stratigraphy) will aim to build a database of terrestrial european stratigraphy (datestra). this is a database of the sites with stratigraphic importance from every country of europe. datestra is therefore an european geographic site-stratigraphical database that will continue the projects carried out by seqs during the previous intra-congress periods when the main goal of the activities was across-europe correlations (pieruccini et al., 2016a; 2017a). however, in many regions quaternary stratigraphical schemes were developed using complex litho-, chrono-, and bio-stratigraphical criteria that made problematic the correlations in terrestrial quaternary systems. this is also due to the fragmentary nature of these records and to the problems related to reliable dating techniques covering the full range of quaternary time. terminology defining the chronostratigraphical setting is often based on local or oldfashioned schemes and the need for a common language/terminology/methodology is strongly necessary in order to share among european quaternary scientists basic geoscientific information. datestra will summarize the main sites with terrestrial quaternary deposits in europe trying to bypass their fragmentary nature and giving rapid access to the sections, techniques and methods used for their study. in order to set the regional names and subdivisions avoiding as much as possible the problems due to local terminology, datestra will focus on the main quaternary stages as assessed by ics-international commission on stratigraphy (gelasian; calabrian; middle pleistocene; upper pleistocene; holocene) giving particular emphasis on the stage boundaries and transitions. this approach should give a summary and overview of the main characters of the subseries/stages across europe. datestra aims to summarize the litho-, bio-, pedo-, morphoand chrono-stratigraphical data that are fundamental for cross-border correlations, quaternary mapping, climate changes reconstructions and natural hazards and related risks assessment. moreover, creation of shared database is also among the main topics of horizon 2020, the financial instrument implementing the innovation union-europe 2020 flagship initiatives aimed at securing europe's global competitiveness. the whole network of quaternary scientists is warmly invited to participate to datestra under the umbrella of inquaseqs; seqs is active since many decades, putting together a high number of quaternary scientists across europe sharing knowledge and information annually through meetings and regular publication of proceedings of these meetings on quaternary international special issues (i.e. zastrozhnov et al., 2018). at the same time, ecr (early career researchers) and dcr (developing countries researchers) scientists are encouraged and granted to present and share during the seqs annual meetings the main quaternary sites, together with their significance, for single countries or regions across europe. in fact, during the seqs meetings, sessions are devoted to datestra and the whole seqs audience is https://doi.org/10.26382/aiqua.2018.aiquaconference informed about the future actions to be taken (http:// datestra-seqs.strikingly.com/) (pieruccini et al., 2016a; 2017a). the seqs meetings in 2016 (armenia) and 2017 (france) already recorded contributions by different countries of europe (danukalova et al., 2017a and b; marks, 2017; gerasimenko, 2017; lefort et al., 2017; korsakova & kolka, 2017; pieruccini et al., 2016b; 2017b) 2. structure of the database the the password for the database is easy; it means easy compilation, the compilers are invited to contribute providing basic information for each site, including basic bibliographic reference. the database should serve to the end-user as a starting point for further and more detailed information. at first, datestra should contain only key sites, such as historically known sites or the better stratigraphically significant and constrained sites from every country of europe. the database should also be easy to query; the enduser should be able to query and find the information needed, i.e. the chronostratigraphical interval and the dating method, the biostratigraphical proxy etc. the structure of the database is therefore conceived taking into account these objectives. each site has a number of attributes (and related domains) and each attribute has a limited number of values, in order to make the database as simpler as possible. the terminology of the values for each attribute have been uniformed based on the iquame 2500 project dictionaries for the quaternary map of europe. the attributes are grouped under 4 main topics: 1 registry these attributes are related to the basic information about name of the site, country, region, geographic coordinates, names and institutions of compilers, date of compilation, type of site, state of preservation of the site. 2 stratigraphy these attributes are related to the basic information about the chronostratigraphical attribution, geochronological method for attribution, reliability of the attribution, depositional environment, presence of unconformities, biological proxies, morphostratigraphy, lithostratigraphy, pedostratigraphy and magnetostratigraphy. 3 correlation these attributes are related to the correlation of the site with climatostratigraphy or mis. the mis attribution is provided for mis intevals as follows: mis 1-19, if single; mis1-19, 19-31, 31-65, 63-103 if intervals of mis. 4 documents these attributes are related to the documents, and their path, attached to the table of the site, i.e. article, photo, table, log etc. the structure and design of the database was ini 186 pieruccini p. et al. fig. 1 scheme of the structure of datestra database with the description of the attributes for each site. tially discussed among colleagues belonging to the aiqua community (italian association for quaternary research) who also contributed with a preliminary compilation of italian quaternary sites. then, these sites and the output on story maps (esri©) were presented to the seqs community (pieruccini et al., 2016c; 2017c). 3. datestra output and expected result the main output of datestra is an open access database with a consistent number of quaternary sites compiled for as many countries as possible of europe. the database will be an open-source tool that will works as a starting point for the european quaternary stratigraphy knowledge, to be implemented and updated by scientists that especially in the future could face problems with old terminology or old references about key-sites that in many cases disappeared or faded away in the memory. the database principles are that it must be: a) concise, containing very basic information but sufficient as starting point for further refined search; b) easy to compile, allowing with few and clear rules its compilation from people with different scientific backgrounds: c) easy to query, this is the crucial point for consultation and correlation across europe. for each compiled site the compilers are asked to provide the table with attributes and values, a short text, few picture and the main references. the sites and related data will also be uploaded on web-gis application like “story maps” (esri©) that allows all the queries in order to give a summary of the potentially correlated quaternary sites across europe. the goal for this intra-congress period is then to present the database at inqua dublin 2019, to the wider audience as possible, opening the road to future actions like extra-european countries or more detailed or functional databases. for this purpose, seqs already applied for a session also dedicated to datestra. references danukalova g., osipova e., yakovlev a., kurmanov r. (2017a) biostratigraphy of the early pleistocene (paleopleistocene) of the southern urals region, russia. seqs2017 meeting, tautavel (france) 10-15 sept. 2017: “quaternary stratigraphy and hominids around europe: tautavel (eastern pyrenees)”. abstract volume, 37. institute of geology, ufimian scientific centre, russian academy of sciences. danukalova g., osipova e., yakovlev a., kurmanov r. (2017b) middle, upper pleistocene (neo pleistocene) and holocene key-sites of the southern uralian region (russia): summary for the database. seqs2017 meeting, tautavel (france) 1015 sept. 2017. “quaternary stratigraphy and hominids around europe: tautavel (eastern pyrenees)”. abstract volume, 42. institute of geology, ufimian scientific centre, russian academy of sciences. gerasimenko n. (2017) the ukrainian candidate sections for datestra. seqs2017 meeting, tautavel (france) 10-15 sept. 2017: “quaternary stratigraphy and hominids around europe: tautavel (eastern pyrenees)”. abstract volume, 65. institute of geology, ufimian scientific centre, russian academy of sciences. korsakova o., kolka v. (2017) pleistocene stratigraphy and key-sections in kola peninsula, north west russia. available data. seqs2017 meeting, tautavel (france) 10-15 sept. 2017: “quaternary stratigraphy and hominids around europe: tautavel (eastern pyrenees)”. abstract volume, 63. institute of geology, ufimian scientific centre, russian academy of sciences. lefort j., danukalova g., monnier j. (2017) datestra in brittany and normandy. the predatestra correlations and other transeuropean considerations. seqs2017 meeting, tautavel (france) 10-15 sept. 2017: “quaternary stratigraphy and hominids around europe: tautavel (eastern pyrenees)”. abstract volume, 51. institute of geology, ufimian scientific centre, russian academy of sciences marks l. (2017) proposal of polish key sites to the data base of the quaternary stratigraphy of europe. seqs2017 meeting, tautavel (france) 10 -15 sept. 2017: “quaternary stratigraphy and hominids around europe: tautavel (eastern pyrenees)”. abstract volume, 50. institute of geology, ufimian scientific centre, russian academy of sciences. pieruccini p., fiebig m., danukalova g. (2016a) ifg 1612f datestra, a database of terrestrial european stratigraphy. quaternary perspectives, 23 (2), 7-8. pieruccini p., fiebig m., danukalova g. (2016b) datestra: a database of terrestrial european stratigraphy (inqua grant 1612f). seqs2016 meeting, yerevan, armenia 3-10 settembre 2016: “bridging europe and asia: quaternary stratigraphy and paleolithic human occupation in armenia and southern georgia, fiebig m., meliksetian k., gasparyan b., arakelyan d. (eds) abstract volume, p. 40. pieruccini p., bertini a., coltorti m., magri d., martinetto e., palombo m., ravazzi c. (2016c) datestra, a database of terrestrial european stratigraphy (inqua grant 1612f): the example of selected sites from italy. seqs2016 meeting, yerevan, armenia 3-10 settembre 2016 “bridging europe and asia: quaternary stratigraphy and paleolithic human occupation in armenia and southern georgia, fiebig m., meliksetian k., gasparyan b., arakelyan d. (eds) abstract volume, p. 54. pieruccini p., fiebig m., danukalova g. (2017a) 1612f datestra: a database of terrestrial european stratigraphy. quaternary perspectives, 24 (1), 1011. pieruccini p., danukalova g., fiebig m. (2017b) datestra: a database of terrestrial european stratigraphy (inqua funded focus group saccom: 1612f). in: seqs2017 meeting, tautavel (france) 10-15 sept. 2017: “quaternary stratigraphy and 187 datestra database of terrestrial quaternary sites of europe hominids around europe: tautavel (eastern pyrenees)”. abstract volume, 40. institute of geology, ufimian scientific centre, russian academy of sciences. pieruccini p., bertini a., coltorti m., magri d., palombo m.r., ravazzi c., sala b. (2017c) the italian contribution to the datestra project (inqua funded focus group saccom: 1612f): a first compilation of the main italian quaternary sites. seqs2017 meeting, tautavel (france) 10-15 sept. 2017: “quaternary stratigraphy and hominids around europe: tautavel (eastern pyrenees)”. abstract volume, 41. institute of geology, ufimian scientific centre, russian academy of sciences. 188 pieruccini p. et al. ms. received: may 8, 2018 final text received: may 14, 2018 amq30(1) 1 monaco scozzafava 2.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 30 (1), 2017, 5 10 a preliminary survey for testing operativity and efficiency of gpr technology by means of unshielded antenna for the study of calderone glacier, central italy angelo monaco 1, marco scozzafava 2 1 studio di geologia, avezzano, italy 2 mcubo engineering, l’aquila, italy corresponding author: a. monaco <angelo.monaco@geologiabruzzo.org > abstract: during july 2015 a survey using gpr technology was carried out over the calderone glacier in the gran sasso d’italia massif (highest peak 2912 m a.s.l.). the main aim of the survey was to verify the usability of bistatic unshielded antenna, uncoupled with the ground, and to assess gpr data quality vs reached depth. the use of this kind of antenna is suggested by the need to operate also over rough and irregular surfaces. the obtained results are to be considered very good, as they easily match with previous results obtained in 1992 and 1998 using gpr technology with a shielded antenna, coupled with ground. the interpretation of data highlights a good stability of the ice mass in the lowermiddle sector of the glacier, and a maximum ice thickness evaluated about 26 m. the choose system was a radsys gpr with unshielded antenna of 150 mhz frequency, to cross an ice thickness lower than 30 m, as supposed by previous researches. keywords: gpr, calderone, glacier, uncoupled antenna, apennine, italy. 1. introduction as well known, the calderone glacier, located in a cirque in the north side of corno grande, gran sasso massif (central italy), is the only glacier of apennine and the southernmost of europe (pecci et al., 1997). as a consequence of the raising air temperature in recent decades, it has undergone a progressive and constant melting (gellatly et al., 1994). numerous studies (e.g., marinelli & ricci, 1916; tonini, 1961; smiraglia & veggetti, 1992) have been conducted to define the glacier geometry and the evolution of the glacial apparatus. they all agree in indicating the presence of an icy mass, of not uniquely defined geometry, covered by a not uniform layer of heterometric debris (fig. 1). the estimated maximum thickness was about 26 m (fiucci et al., 1997; de sisti et al., 1998). in view of the logistical difficulties and peculiarities of the survey site, the gpr (better known in literature as ground penetrating radar) has proved to be the most suitable instrument for the deep analysis of the glacier body (bogorodskiy et al., 1985; funk et al., 1993; haeberly et al., 1983), thanks to the progressive reduction of the overall dimensions of the equipment and to its great resolution power and data processing capabilities. to fiucci and collaborators is due the first campaign of investigations by gpr technique performed in the summer of 1992; de sisti et al. (1998) conducted a similar survey in july 1998. this report presents the results of a preliminary gpr survey performed on 26 july 2015 on the lowermiddle sector of the glacier. the survey was carried out quickly with an unshielded antenna, uncoupled with the ground, which has large footprint but anyway a low weight making it possible to extend the acquisition profiles to rough zones, such as the edges of the glacier covered by seasonal snow (fig. 2). the aim of the survey was to verify the effective operativity in such surface conditions, as well as the quality of the results obtained without adherence between antenna and ground, which usually leads to signal attenuation. 2. devices and method the principle which drives a gpr equipment can be summarized as follows: from the ground surface the antenna transmits a pulse-type signal (electromagnetic wave). intercepting an electromagnetic discontinuity in the crossed medium (caused by an object embedded in it or by a change of the medium itself), part of the incident wave is reflected toward the ground surface; the reflected wave is acquired by a receiving antenna at the ground surface. transmission and reflection of electromagnetic waves are driven by the following electromagnetic parameters: relative dielectric constant, generally indicated more briefly with the term "permittivity", that has the most influence on the waves speed; conductivity, a parameter that limits the investigation depth, since the greater the conductivity the greater is the absorption. during signal acquisition, the gpr registers the travel time of the reflected wave, and subsequently converts it into distance covered by the wave, as a function 6 monaco a. & scozzafava m. fig.1 – a sw view of the calderone glacier. on the right the front moraine can be seen. fig.2 the used gpr system: unshielded antenna and acquisition unit. firn covers debris (t1 scan). 7 a preliminary survey for testing operativity and efficiency of gpr technology ... of the permittivity assumed for the medium. in the case of ice, the assumed value is equal to 4, in accordance with previous studies (e. g. daniels, 2004) the equipment used, mod. zond 12e radsys, consists of an acquisition and digitizing unit, compact and transportable by the operator, together with a netbook for recording and displaying data. the unit is connected to an antenna with a frequency suitable to the prospecting targets (depth and resolution), whereas low frequencies mean greater depth investigation and less resolution, and vice versa. therefore in this survey, considering the expected thickness of the ice mass, a low frequency antenna (150-75-38 mhz, set to 150 mhz) not coupled with the ground, was used. the gpr scans were positioned using reference points from which distances and elevations were measured with a nikon, model forestry pro 2 trigonometric diastimeter. 3. data acquisition the investigated area corresponds to the lower-middle glacier sector, down to the southern side of the terminal moraine (2696 m a.s.l.). all the height values in the scans below are relative to the snow conditions at the survey date; all the scans lengths are defined in a horizontal projection. three scans were performed with the aim to draw the geometry of the glacier bottom. the scans location is shown in fig. 3, on an aerial-photographic base. a longitudinal scanning (scanning l, fig. 4a) was performed in the north-south direction, parallel to the axis of the glacier. the starting point (to the north) was set at an altitude of 2670 m a.s.l., approximately corresponding with the contact between the moraine outcrop and the snow cover existing at the date of survey. the scanning passed through the lowest point, at an altitude of 2668 m a.s.l., and finally reached a length of 119 m, with the end point (to the south) at an altitude of 2700 m a.s.l. subsequently, a first transverse scan was performed (scanning t1, fig. 5a) with a west-east direction, intersecting the longitudinal scan near its starting point. the tranverse length was 152 m, with a starting point (to the west) at an altitude of 2705 m a.s.l. and an end point (to the east) at a height of 2676 m a.s.l. the lowest point corresponds to the intersection with the longitudinal scan l. the third scan (scanning t2, fig. 6a) intersects, with a west-east direction, the midpoint of the longitudinal scan and is 120 m long. the starting point (to the west) is located at an altitude of 2697 m a.s.l., the lowest point at 2669 m a.s.l. and the end point (to the east) at 2678 m a.s.l. in fig.7 the location of the scans is shown on a photographic base illustrating the snow conditions on july 11, slightly higher than those found on july 26, 2015. 4. results first step in data rendition was the examination of glacial and snow conditions as visible in site at the survey time, on 26 july 2015, then the gpr analysis was carried out with the aim of checking the presence and thickness of the following homogeneous units: 1. shallow firn; 2. debris cover blanket; 3. ice; 4. limestone bedrock. in the examination just basic processings were done, that is background removal run, appropriate signal gain and moveout correction, or rather parallax correction according to antenna size in order to get the right reading of deepness and achieve the correct reading of depth. under graphic rendering of soundings (radargrams) the elevation profiles of sections were drawn carefully getting a better view of glacier topography and a truly shape of the homogeneous units. finally, the altitude references (i.e. zero point of the radargram depth scale) were aligned to the lowest points of the bedrock surface in each profile, thus allowing a more convenient comparison between the different soundings. in the figures 4b, 5b and 6b coloured areas show the existence of a well-marked discontinuity, easily ascribable to the contact surface between the shallow firn layer and the underlying debris cover blanket. this interpretation is confirmed by the outcrop of such a contact surface on the initial section of profiles l and t1 (fig. 2, fig.3 the calderone glacier: aero-photographic image with contour levels and scan sections. 8 fig. 4b and 5b). all the radargrams show a well-defined discountinuity at the basis of the debris layer, confirming its scarce thickness as already pointed out to by fiucci et al. (1997) and de sisti et al. (1998). below this discontinuity, the lack of anomalies in the reflected signal allows to characterize the existence of a uniform mass, recognizable as ice. in the l scan radargram, the excellent signal quality allowed a reliable interpretation of the shape of the calderone glacier lower-middle part along the longitudinal axis of the glacial basin (fig.4b). the deepest discontinuity looks particularly clear; it is most likely ascribable to the contact between the glacier and the bedrock. a little beyond the point of 100 m the maximum depth is visible with regard to the firn surface at the moment of sounding, valuable about 32 m. as a result, the maximum ice thickness would amount to 26 m, bearing an overlying debris cover one meter thick and a 5 m thick firn blanket. the initial section (north) of the scan appears to be easily construable; the bedrock “rise” making up the basin threshold, and the above debris stockpile of the front moraine are well marked. in the final portion of t1 scan (fig. 5b) the contact between the glacier and the bedrock appears less clear, so that the direct contact between debris cover and limestone bedrock is possible, there locating the probable margin of ice mass at the glacier eastern side, just before the frontal moraine. similar reading uncertainty does exist in the neighborhood of point 100 m of scan t2 (fig. 6b), where presence of ice with a large amount of debris inside (rock glacier) is conceivable. anyway, t2 scan points out an unexpected thickness of ice at the western side of glacier basin, that as about 15 m in the first section (west) of the scan. ice shows fair thickness in the eastern side of the basin, too. fig. 4 georadar scan section l (a) and the same section with the units enhanced using different colours (b) . a b monaco a. & scozzafava m. 9 fig. 5 georadar scan section t1 (a) and the same section with the units enhanced using different colours (b). fig. 6georadar scan section t2 (a) and the same section with the units enhanced using different colours (b). fig.7 the georadar sections in a 3d view. a a b b a preliminary survey for testing operativity and efficiency of gpr technology ... 5. conclusions the execution of a preliminary survey on the calderone glacier, carried out with gpr technique and non surface-coupled antenna, has allowed to check the full practicality and efficiency of such a system, which permits to overcome inconveniences and limitations resulting from operating with surface-coupled antenna in case of strongly roughed surfaces. the quality of recorded signal has proved to be pretty good and satisfying, allowing an excellent depth of survey; the ice maximum thickness, as detected in the longitudinal scan, resulted equivalent to 26 meters, perfectly in agreement with previous studies, proving a significant and unexpected preservation of the icy mass in the last two decades. the scan processing has provided useful hints about the possible shape of the units that make up the glacier complex, with special regard to the front moraine morphology and the bedrock basal surface. furthermore, important information has been obtained concerning the unexpected thickness of sides of the glacier in the central area. positive results achieved with the carried out preliminary survey allow the planning of a more thorough and careful survey with the same technique and equipment, focused to get a detailed mapping of the glacier shape, that will be obtained by means of a regular grid of scans and based on a careful land survey. acknowledgements the authors wish to thank the meteorological association “aq caput frigoris”; special thanks are given to members thomas di fiore, alessandro ferrante, giampiero manzo, manuel montini, valerio sorani, francesco vaccaro for their technical and logistical support. thanks to mr. cristiano iurisci for the useful hints and a preliminary land survey of the site. references bogorodskiy v.v., bentley c.r., gudmandesn p.e. (1985) radio-glaciology. d. reidel publ. co., dordrecht, holland, pp. 254. de sisti g., marino a., pecci m. (1998)indagini georadar sul ghiacciaio del calderone del gran sasso d’italia: primi dati relativi alla ricostruzione dello spessore di ghiaccio residuo. gngts, atti del 17° convegno nazionale, pp. 6. daniels d.j. (2004) ground penetrating radar. the institution of engineering and technology, iet, pp. 725. fiucci a., gigante b., rossi c., smiraglia c., veggetti o. (1997) the calderone glacier (gran sasso d’italia). determination of ice thickness and bedrock morphology by means of radio-echo sounding. geografia fisica e dinamica quaternaria, 20, 305-308. funk m., bosch h., valla f. (1993) mesures del epaisseurs de glace par la methode radar au glacier de sarennes. societé hydrotecnique de france, section de glaciologie, reunion des 11 et 12 mars, grenoble, pp. 13. gellatly a.f., smiraglia c., grove j.m., latham r. (1994) recent variations of ghiacciaio del calderone, abruzzi, italy, journal of glaciology, 40, 136, 486-490. haeberly w., wachter h.p., schmid w., sidler c. (1983) erste erfahrungen mit dem us geological survey monoplus radioecholot im firn, eis und permafrost der svhweizer alpen, zeitschr. gletscherk. glazialgeol., 19, 61-72. marinelli o., ricci l (1916) alcune osservazioni sul ghiacciaio del gran sasso. riv. geogr. it, 23, 399-405. pecci m., smiraglia c., d’orefice m. (1997) il ghiacciaio del calderone. rivista aineva “neve e valanghe”, 32 (novembre 1997), pp. 57. smiraglia c, veggetti o. (1992) recenti osservazioni sul ghiacciaio del calderone (gran sasso d’italia -abruzzo). boll. soc. geogr. it. ser xi, 4, 269302. tonini d. (1961) il ghiacciaio del calderone del gran sasso d’italia. boll. com. glac. it., ser. 2, 10, 71135. 10 monaco a. & scozzafava m. ms. received: may 12, 2016 final text received: december 3, 2016 amq abs zuffetti et al tepro 257-260.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 257 260 significance of the morphological and stratigraphic surfaces in the quaternary po plain: the san colombano tectonic relief (lombardy, italy) chiara zuffetti, riccardo bersezio, luca trombino dipartimento di scienze della terra, università degli studi di milano, milano, italy. corresponding author: c. zuffetti <chiara.zuffetti@unimi.it> abstract: the recent geological, geomorphological, pedological and structural surveys performed at the san colombano tectonic relief document a late quaternary tectonic activity of the structure, located at the po plain-northern apennine border in lombardy (italy). the new maps, corroborated with (palaeo-) geopedological analyses, allow to unravel the composite nature of the morphological and stratigraphic surfaces bounding the observed units and landforms, and to relate them to the climatic and tectonic events that interacted during the late quaternary at the apennine-po plain border. keywords: northern apennine, po plain, quaternary, san colombano hill, soil, stratigraphy 1. introduction the interaction between tectonics and climate cycles has determined the mobility of depositional settings at the border between the apennines and the po plain during the quaternary, which results in a great complexity of geomorphological and stratigraphic features. stratigraphic boundaries and morphological surfaces are fundamental elements to recognize the periods and sites of surface stabilization and pedogenesis (morphological surfaces) from those where mostly erosion and/or aggradation occur (stratigraphic boundaries). paleosol analysis helps to characterize these two different types of surfaces, which might represent also palaeoclimatic and palaeoenvironmental markers, providing additional chronological constraints to the quaternary geological and morpho-tectonic processes (costantini, 2017). hence, the integration between detailed geological mapping of the quaternary sediments and the sedimentological and geopedological characterization of the stratigraphic boundaries is necessary to unravel the origin of landscape in complex mobile settings. from this perspective we focus on the san colombano hill in the po plain of lombardy (fig. 1; desio, 1965), as one of the main evidences of late pleistocene n-apennine tectonics affecting the s-alpine sourced alluvial systems. here, the available regional geological maps (anfossi et al., 1971; boni, 1967) and pedological studies (ersaf, 2013) have never been integrated in a comprehensive quaternary stratigraphic framework, and the late quaternary geological evolution of the structure, mainly based on regional geomorphological studies (benedetti et al., 2003; burrato et al., 2003; pellegrini et al., 2003), is still under debate. starting from the new geological, geomorphological and structural surveys carried out on the hill (zuffetti et al., 2018), and accounting for the new geopedological data which have been recently submitted for publication, here we focus on the characterization of the stratigraphic boundaries and morphological surfaces of the san colombano hill area. the main aim is to highlight their role as indicators of the incremental morpho-tectonic changes at the origin of the hill landforms during the late quaternary, and to unravel the most effective controlling factors on their origin. 2. materials and methods detailed geological and geomorphological mapping at 1:10.000 scale have been carried out in the san colombano hill area. ubsu (issc, 1987) classification was applied when possible to the quaternary continental units, following the criteria adopted in the recent mapping projects of italy. sedimentological, geomorphological and structural analyses accompanied field surveys and the results are presented in zuffetti et al. (2018). the geopedological characterisation of the stratigraphic boundaries relies on a distributed mapping of soil textures and colours, integrated by detailed analyses on five soil profiles, selected as reference for the features of the top boundary of the mapped late pleistocene stratigraphic units and for the most prominent morphological surfaces. geopedological field description, laboratory analyses and micromorphological observations were performed following the conventions of wrb (2015), ministero per le politiche agricole (1999), stoops et al. (2010), respectively. age constraints are based on new and available osl and radiocarbon datings (baio et al., 2004; bersezio et al., 2004; panzeri et al., 2011). 3. results the san colombano hill exposes the uplifted and folded marine miocene and calabrian units (sant’agata fossili marls and san colombano fm.; ‘m’ in fig. 2), unconformably overlain by the late pleistocene alluvial https://doi.org/10.26382/aiqua.2018.aiquaconference pedogenised and deformed deposits (cascina parina synthem, ‘cps’ and invernino synthem, ‘ins’, fig. 2). the sequence is in turn modelled by the late pleistocene to holocene processes and covered by sediments, which belong to the monteleone synthem (‘mls’, fig. 2) and are located along the slopes and within the valley network of the hill. the eastern sectors of the hill consist of fault blocks (fig. 2) laterally dissected by conjugate faults while the northern and southern slopes develop from wnw-ese directed normal faults stepping towards the adjacent plain (zuffetti et al., 2018). the lower boundary of cps (late pleistocene) is a high rank angular unconformity, composed by the progressive terracing of cps alluvial systems on the uplifting substratum (zuffetti et al., 2018). this middle-late pleistocene unconformity encompasses the regional regressive sedimentary cycles recorded in the subsurface of the central po plain (ghielmi et al., 2013). geopedological analyses performed on both cps, ins and on the loess deposits at their top, result in the identification of some surfaces of morphological, tectonic and depositional stabilization, differently preserved and dissected throughout the san colombano hill. the most complete sequence is observed in the lowermost hill sector, where a highly developed and red paleosol is covered by two stacked loess-paleosols to soil sequences (buried loess l1, exposed loess l2; fig. 2). the oldest loess (l1) is ascribed to the end of cps depositional cycle (pre-lgm), the youngest (l2) to the end of lgm, post-dating the deposition of ins. age constraints are provided by osl and radiocarbon datings (panzeri et al., 2011; bersezio et al., 2004; zuffetti et al., 2018). the associated soils (fig. 2) mark two phases of climatic stabilization under interglacials. a comparable interpretation was proposed for soils and paleosols described on loess covers at both the northern (zerboni et al., 2014) and southern fringes of the po plain (cremaschi et al., 2015; maestrelli et al., 2018). hence, the surface at the top of cps in the lowermost hill sector corresponds to a geomorphic surface of stabilization (s, fig. 2), covered by loess l2. a comparable interpretation is deduced from the sections studied at the uppermost fault blocks, where the late-lgm l2 loess covers a geomorphic surface of planation, subsequently stabilized (‘e+s’ surface, fig. 2). layers of colluvium reworking pedorelicts of highly weathered material rest on the unconformity, below the loess cover of the intermediate fault block (fig. 2). in the northern fault block, both alluvial ins and l2 are preserved and no paleosols were observed (fig. 2); the evidence of paleosol redeposition in this interval consists of colluvial sediments derived from developed and hydromorphic paleosols, interposed between alluvial ins and l2 by means of a low rank stratigraphic boundary (fig. 2). in this sector, the unconformity bounding the bottom of ins is a high rank erosional surface, resulting from alluvial terracing during the lgm depositional cycle, as confirmed by stratigraphic correlation to the adjacent dated sediments north of the relief (bersezio et al., 2004; zuffetti et al., 2018). 4. discussion and conclusions the new maps (zuffetti et al., 2018), combined with detailed pedo-stratigraphic analyses, provide a useful framework to discuss the interaction between tectonic 258 fig. 1 location of the san colombano hill in the structural framework of the central po plain (italy). the san colombano structure (sc) corresponds to one of the northernmost thrusts of the buried front of the northern apennine emilia arc. buried n-apennine thrusts from bigi et al. (1990); buried s-alpine thrusts simplified from fantoni et al. (2004). zuffetti c. et al 259 and climatic controls at the origin of the stratigraphic and morphological surfaces that characterize the san colombano hill. the late quaternary synthems mapped on the hill are bounded by composite unconformities that originated in part during tectonic displacement and, in part, during periods when specific sites where stabilized. in situ paleosols testify the existence of locally non-erosional unconformities during the late pleistocene, related to surface stability, where the main controlling factor was climatic. l1 and l2 loess are mostly preserved at these sites. conversely, truncated and redeposited paleosols dominate in sites of active tectonic displacement, as observed in the easternmost fault blocks; here, latest pleistocene tectonic increments (zuffetti et al., 2018) acted in soil erosion and mobilization. the basal unconformity of the lgm ins is composed by erosional surfaces which join progressively deposited along the dissected fault blocks. the present work outlines the importance of considering how tectonics interacts with climate-driven depositional and soil-forming processes to produce stratigraphic and geomorphological surfaces. their significance is relevant for mapping purposes and to constrain correlation of continental successions within the stratigraphic framework of the late pleistocene po basin infill. the regional meaning of the correlative surfaces detected in the subsurface of the basin is the object of the wider ongoing research. acknowledgments the research was supported by carg funds to rb. the paper is a part of cz phd project, under supervision of rb. references anfossi g., desio a., gelati r., laureri s., petrucci f., venzo s. (1971) note illustrative della carta geologica d’italia. f. 60, piacenza. baio m., bersezio r., bini a. (2004) assetto geologico della successione quaternaria nel sottosuolo tra melegnano e piacenza. il quaternatio, 17, 355359. benedetti l.c., tapponnier p., gaudemer y., manighetti i. (2003) geomorphic evidence for an emergent active thrust along the edge of the po plain: the broni-stradella fault. journal of geophysical research, 108, 2238, doi:10.1029/2001jb001546. bersezio r., pavia f., baio m., bini a., felletti f., rodondi c. (2004) aquifer architecture of the quaternary alluvial succession of the southern lambro basin (lombardy italy). il quaternario, 17, 361-378. bigi g., cosentino d., parotto m., sartori d., scandone p. (1990) structural model of italy. progetto finalizzato geodinamica, cnr. boni a. (1967) note illustrative della carta geologica morphological and stratigraphic surfaces in the po plain fig. 2 n-s and e-w sections showing the relations between the late quaternary soils and paleosols and stratigraphic boundaries across the san colombano hill. m: undifferentiated marine units (upper miocene to calabrian); cps: cascina parina synthem (late pleistocene); l1: pre-lgm loess; ins: invernino synthem (latest pleistocene); l2: late-lgm loess; mls: monteleone synthem (late pleistocene-holocene). thickness of the lines representing the stratigraphic boundaries is proportional to their rank. s buried and/or exposed stabilization surface; e erosional surface. d’italia. f. 59, pavia. burrato p., ciucci f., valensise g. (2003) an inventory of river anomalies in the po plain, northern italy: evidence for active blind thrust faulting. ann. geophys. 46 (5), 865-882. costantini e.a.c. (2017). paleosols and pedostratigraphy. applied soil ecology, 1-4. doi:10.1016/j.apsoil.2017.09.021. cremaschi m., zerboni a., nicosia c., negrino f., rodnight h., spötl c. (2015) age, soil-forming processes, and archaeology of the loess deposits at the apennine margin of the po plain (northern italy): new insights from the ghiardo area. quaternary international, 376, 173-188. doi: 10.1016/j.apsoil.2017.09.021. desio a. (1965) i rilievi isolati della pianura lombarda ed i movimenti tettonici del quaternario. rendiconti dell’istituto lombardo di scienze e lettere, a, 881894. ersaf (2013) carta dei suoli in scala 1:50.000 della pianura e collina lombarda. ( h t t p : / / w w w . ers a f . l o m b a r d ia . i t / u p l o a d / e r s a f / soilqualimon/pdf/qdr_110.pdf) fantoni r., bersezio r., forcella f. (2004) alpine structure and deformation chronology at the southern alps-po plain border in lombardy. bollettino della società geologica italiana, 123, 463-476. ghielmi m., minervini m., nini c., rogledi s., rossi m. (2013) late miocene-middle pleistocene sequences in the po plain-northern adriatic sea (italy): the stratigraphic record of modification phases affecting a complex foreland basin. marine and petroleum geology, 42, 50-81. doi:10.1016/j.marpetgeo.2012.11.007. international subcommission on stratigraphic classification (1987). unconformity-bounded stratigraphic units. geological society of america bulletin, 98, 232-237. maestrelli d., benvenuti m., bonini m., carnicelli s., piccardi l., sani f. (2018) the structural hinge of a chain-foreland basin: quaternary activity of the pede-apennine thrust front (northern italy). tectonophysics, 723, 117-135. doi:10.1016/j.tecto.2017.12.006. ministero per le politiche agricole (1999) metodi ufficiali di analisi fisica del suolo. d.m. del 13 settembre 1999. gazz. uff. suppl. ordin. n. 248 del 21.10.99. panzeri l., zembo i., bersezio r., martini m. (2011) calibration of osl data: mismatch between stratigraphy and osl chronology pf sediments from the po plain. il quaternario, 24, 114-116. pellegrini l., boni p., carton a. (2003) hydrographic evolution in relation to neotectonics aided by data processing and assessment: some examples from the northern apennines (italy). quaternary international, 101-102, 211-217. doi:10.1016/s1040-6182(02)00103-9. stoops g., marcelino v., mees f. (2010) interpretation of micromorphological features of soils and regoliths. elsevier, oxford, uk. wrb iuss working group (2015) world reference base for soil resources 2014, update 2015 international soil classification system for naming soils and creating legends for soil maps, world soil resources reports. fao, rome. zerboni a., trombino l., frigerio c., livio f., berlusconi a., michetti a.m., rodnight h., spotl c. (2014) the loess-paleosol sequence at monte netto: a record of climate change in the upper pleistocene of the central po plain, northern italy. journal of soils and sediments, 15, 1329-1350. doi:10.1007/s11368-014-0932-2. zuffetti c., bersezio r., contini d., petrizzo m.r. (2018) geology of the san colombano hill, a quaternary isolated tectonic relief in the po plain of lombardy (northern italy). journal of maps, 14, 199-211. doi:10.1080/17445647.2018.1443166. 260 zuffetti c. et al ms. received: may 21, 2018 final text received: may 23, 2018 amq sr001 wolter 139-148.pub a review of methods used to investigate structural control on slope instability. andrea wolter engineering geology, gns science, avalon, lower hutt, new zealand. corresponding author: a. wolter <a.wolter@gns.cri.nz> abstract: many features and phenomena, such as slope morphology, climate, hydrogeological and hydrological conditions, and material strength, contribute to slope instability. one of the most important preconditioning factors, particularly in rock slopes, is structural control. structural control includes any tectonic processes or features that may influence landslide initiation, movement, or termination, including in situ stress conditions, discontinuities, faults, folds, and foliation. structures affect not only the failure geometry, such as headscarp shape, but also deposit volume, morphology, block size, damage, and emplacement behaviour. structural features and processes thus influence all aspects of landslide behaviour, from the development of unstable conditions to deposition. interestingly, mass movement studies can also highlight structures, and contribute to detailed mapping of previously unrecognised faults, folds, and other features. methods such as regional lineament mapping, traditional fieldwork, photography and photogrammetry, lidar surveys, insar interpretation, and numerical modelling are used to analyse structural features and processes related to slope instability. this short paper presents an overview of these methods and highlight their applications in a case study. keywords: structural control, slope instability, methods, vajont landslide. � available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 33 (2), 2020, 139-147 1. introduction structural geological features and processes, such as discontinuities, folds, faults, foliation, and in situ stresses, are recognised as important controls on slope instability, particularly in rock slopes (agliardi et al., 2001; stead and wolter, 2015) (fig. 1). in this context, discontinuities include pre-existing lineaments that may influence failure geometry and behaviour, whereas faults are lineaments that typically produce damage or shear zones of weaker material surrounded by more competent material (loew et al., 2012; milmo et al., 2014; bonilla-sierra et al., 2015). fold axes are commonly weak zones, and fold geometry may influence failure geometry (badger, 2002; jaboyedoff et al., 2011; humair et al., 2013). foliation may affect sliding zone development (braathen et al., 2004; adhikary and dyskin, 2007; vick et al., 2020). the tectonic inheritance and in situ stress conditions of a given slope influence slope stability, and rock mass behaviour and damage (hoek et al., 2009; ambrosi and crosta, 2011; agliardi et al., 2013; stead and eberhardt, 2013; elmo et al., 2018). inclusion of structural control analysis when studying mass movements contributes to improved understanding of failure preconditioning, initiation and behaviour at various scales, and ultimately to landslide hazard and risk reduction. for example, glastonbury and fell (2000) and stead et al. (2006) illustrated how structures affect failure mechanisms, from translational to complex multi-mechanism failure. recent analysis of structural control within the creeping moosfluh slope adjacent to the aletsch glacier in switzerland examines the application of sophisticated monitoring to determine the role of structural control in developing failure mechanisms and in slope stability evolution (glueer et al, 2019a, b; manconi et al., 2019). in troms, norway, vick et al. (2020) focus on rock slope deformations (rsds), highlighting the role of foliation, discontinuities, and faults in rsd formation and evolution and presenting a new geotechnical model for these failures. aside from recognising the importance of structural control as in the above examples, incorporating techniques traditionally used in structural geology into geotechnical assessments of slopes facilitates analysis and improves slope characterisation. for example, havaej and stead (2016) applied the concept of the strain ellipsoid to brittle fracture and damage in open pit mines and natural slopes, determining an “ellipsoid of damage”. the aim of this short paper is to provide a review of methods used to investigate the influence of structural geological features and processes on slope instability. methods are described in the next section, followed by a case study highlighting the application of several of these methods to the famous vajont landslide and a discussion of the methods. 2. methods analysis of slope stability has incorporated numerous techniques to improve understanding of failure mechanisms, including site investigations, drilling, groundwater, displacement and climate monitoring, geo https://doi.org/10.26382/amq.2020.05 140 wolter a. fig. 1 structural features and controls (such as folds, fault zones, rock bridges, crown cracks, transverse cracks and ridges, and radial cracks) on landslides, with methods used to investigate them represented by icons. see tab. 1 for legend of icons. tab. 1 summary of methods used to investigate structural features and processes affecting slope stability. note that field methods here include laboratory methods for simplicity. gsi = geological strength index; jrc = joint roughness coefficient; los = line-of-sight. 141 methods used for structural control on slope instability physical methods, remote sensing, and physical and numerical simulations. figure 1 and tab. 1 summarise the traditional and novel methods applied to the analysis of slope instabilities and their features, focussing on structural control and features, and separated into field methods, remote sensing and visualisation, and simulation and modelling. 3. case study 3.1. background the vajont landslide is a well-known ~270 million m3 event that failed catastrophically on october 9th, 1963 in the dolomites of northern italy, approximately 100 km north of venice (fig. 2). the failure initiated on the southern valley wall of the vajont valley on the flank of mt. toc (peak at 1921 m asl), above the vajont dam, which was the highest double-arch dam in the world at the time of the disaster. the sudden failure caused a displacement wave of the vajont reservoir that spread upvalley and downvalley, overtopped the dam, and flooded the main piave valley below. resulting in just under 2000 deaths, the vajont catastrophe is cited as one of the worst engineering and natural disasters in history. the landslide is among the most researched slope failures in the world, with over 200 studies on its geological, hydrogeological, geotechnical, and social aspects (cf. genevois and ghirotti, 2005; superchi et al., 2010; paronuzzi and bolla, 2012; genevois and tecca, 2013). several critical aspects, such as the significance of changing hydrological and hydrogeological conditions and centimetre-scale clay beds, and the existence of a “paleoslide”, have been discussed for decades (cf. hendron and patton, 1985; semenza, 2010). only recently have geomorphological and structural preconditions and regional evolution been investigated in relation to the vajont landslide. several compressional deformation events shaped the dolomites before and during the late miocene alpine orogeny, including the neoalpine and dinaric deformations. the e-w oriented vajont valley follows the erto syncline, an e-ese plunging recumbent fold that formed during the neoalpine event and was affected by the belluno thrust to the south and the monte borgá and spesse thrusts to the north. the vajont landslide is located on the southern refolded limb of the erto syncline (ravagnan, 2011; massironi et al., 2013). the recently recognised open massalezza syncline (massironi et al., 2013), with a fold hinge oriented n-s and located in the centre of the vajont landslide along the massalezza stream (fig. 2), is associated with the dinaric deformation event and creates the bowl shape observed in the landslide failure scar. interference patterns between the neoalpine and dinaric fold generations contribute to the complex morphology of the failure scar (bistacchi et al., 2015). two faults bound the vajont landslide. the col tramontin fault, a sub-vertical splay of the croda bianca reverse fault, acts as the eastern lateral release. the col delle erghene normal fault forms part of the western lateral and rear release of the landslide. other faults surrounding the landslide include the col delle tosatte fig. 2 location and context of the vajont landslide. 1 vajont landslide failure scar, 2 vajont landslide deposit, 3 vajont dam, 4 pineda landslide deposit (prehistoric failure), 5 col tramontin fault, 6 croda bianca fault, 7 col delle erghene fault, 8 massalezza stream. (modified after: wolter et al., 2014.) reverse fault and the regionally significant belluno flatramp-flat thrust system (massironi et al., 2013). 3.2. investigations on structural features and control at vajont to study the effects of the tectonic setting on failure kinematics and dynamics, engineering geological, structural geological, geophysical and geotechnical methods have been applied to the vajont landslide. for example, bistacchi et al. (2015) constructed a 3d geological model incorporating borehole, morphological, and geological data to characterise damage within the deposit as well as tectonic structures influencing the failure, and petronio et al. (2016) used p-wave, shwave, and surface wave analysis to characterise the rock masses involved in the vajont landslide. paronuzzi and bolla (2015) investigated the interaction of preexisting tectonic discontinuities with discontinuities formed due to gravitational stresses within the vajont landslide area, based on discontinuity orientation. wolter et al. (2014, 2015) used terrestrial photogrammetry, engineering geomorphological analysis and mapping, and engineering geological field investigations to characterise the vajont landslide scar and deposit. through these studies focussed on structural control, several insights have been gained. detailed morphological and structural investigations of the failure scar influenced mainly by interference patterns between the two fold generations mentioned above using methods such as photogrammetry, roughness characterisation, and block statistics, indicated smooth and rough areas of the scar, with implications for where rock bridges and concentrated damage could have formed within the sliding zone (fig. 3) (massironi et al., 2013; wolter et al., 2014). lineament mapping shows the influence of tectonic discontinuities on the geometry of the failure. the roughness of the failure scar and the locations of the col tramontin fault and massalezza syncline also explain the separation of the landslide deposit into several blocks (e.g., wolter et al., 2015). continued 142 fig. 3 roughness classes on the vajont landslide scar, based on block statistics. class 1 represents areas that are largely planar and smooth, with roughness increasing to class 4. rougher areas are more likely to have caused dilation of the failure mass over asperities and/or rock bridge failure through asperities, with implications for movement behaviour. (source: wolter et al., 2014.) wolter a. evolution of the failure scar post-1963 has focussed in a particularly active area under a fold visible in the failure scar (wolter et al., 2014). the vajont landslide deposits include areas of compression and extension, as indicated by morphological features such as transverse ridges and internal shear zones on engineering geomorphological maps (fig. 4) (wolter et al., 2015). these deformed zones suggest further separation of the landslide mass into individual blocks, and they aid in determining the movement behaviour of the catastrophic landslide. numerical modelling of the vajont landslide, including continuum, discontinuum, and hybrid simulations, has suggested that internal damage developed prior to catastrophic failure at critical locations within the rock mass, as also observed in morphological and structural geological field investigations. modelling suggests that strain concentrated within an ellipsoid of damage, 143 and certain pre-existing discontinuities likely separated the failure mass into several blocks (wolter et al., 2013; havaej et al., 2015). 4. discussion and conclusion numerous methods have been developed to analyse structural control on slope failures. the following discusses some of the caveats and limitations of methods mentioned in this paper. any data collection method must be employed with care and expert judgement, as subsequent analysis is only as good as the dataset input. for example, particularly when investigating structural features, structural domains within the study area should be considered. scale of observation is also an important consideration. structural geologists commonly examine features either at the regional or microscopic scale to determine tectonfig. 4 morphostructural features of the vajont landslide deposits, showing zones of extension and compression, as well as blocks within the deposit. (source: wolter et al., 2015.) methods used for structural control on slope instability ic history. although these scales of analysis provide context for slope-scale investigations, meso-scale features are often more significant to slope stability. in fact, slope investigations can identify previously unknown structures such as local folds and faults, as seen in the vajont landslide case above. field (and laboratory) methods remain essential in assessing rock masses and discontinuities, as well as their role in failure kinematics and dynamics. it is only through these methods that properties such as material strength can be quantified. in recent years, using smartphone applications to measure discontinuity, fold, and foliation orientation, as well as collecting other geological data, has started to displace the use of a compass. apps allow much more efficient collection of data and can reduce time spent in precarious field environments. however, their precision and accuracy have been debated (vanderlip, 2016; allmendinger et al., 2017; lee et al., 2018; nováková & pavlis, 2019), and it is still highly recommended to check the accuracy of the app chosen and to calibrate apps using a compass frequently (up to one in every 10 app measurements). understanding the theory behind the data being collected is also important to avoid poor quality or erroneous data. remote sensing applications allow data to be gathered in otherwise inaccessible areas and over large areas and have become widely used to investigate and monitor slopes. these methods require specialised knowledge and awareness of their limitations, some of which are listed in tab. 1. scaioni et al. (2014), francioni et al. (2017) and stead et al. (2019) provide further review of remote sensing as applied to unstable slopes. augmented and virtual reality techniques are relatively new to structural geology and slope investigations. they have proven to be useful tools in visualising the often multi-layered and complex datasets gathered using other methods. although not used to map or model phenomena directly yet, there are some promising developments (e.g., mysiorek et al., 2019). numerical modelling, powerful when used appropriately, should be seen as a conceptual tool to aid in understanding physical processes. like remote sensing methods, numerical methods require highly specialised knowledge. with the increased development of userfriendly interfaces, it is particularly important to have well-defined research goals, and to know the limitations of the approach used as well as the fundamental science underlying each study. stead and wolter (2015) discuss numerical modelling as applied to structural control in slopes in more detail. the incorporation of artificial intelligence (ai), particularly machine learning, into slope stability analysis is a relatively new development, and has allowed for more efficient processing of large datasets. landslide susceptibility assessment currently applies ai most frequently. studies such as dickson & perry (2016), who identify controls on coastal cliff stability using machine learning, and �uri� et al. (2019), using machine learning to classify slopes as stable, dormant or active in belgrade, nonetheless show broader applications to slope stability. for a review of machine learning methods applied to structural geology, see gunderson et al. (2019). this paper has highlighted methods applied to slope investigations, focussed on the characterisation of structural features and processes that may control slope instability. although each of the methods presented provides data and can be used to gain insight into failure mechanisms and behaviour related to structural control, studies benefit greatly from using an integrated approach, combining multiple methods. this combined approach deepens understanding and reduces uncertainty. after all, each method is simply one tool in the endeavour to comprehend complex natural processes. acknowledgements the author would like to thank the 2019 field school committee for organising an engaging excursion as well as the publication of this special issue. thanks also to the helpful comments of two reviewers and the editor. references adhikary d.p., dyskin a.v. 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(2017) structural geology analysis in a disaster-prone of slope failure, merangin village, kuok district, kampar regency, riau province. journal of geoscience, engineering, environment, and technology, 2(4), 249-254. methods used for structural control on slope instability ms. received: may 5, 2020 revised: july 30, 2020 accepted: august 1, 2020 available online: november 30, 2020 148 sess 1_160211.pub il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 first recovery of marine quaternary deposits from geognostic boreholes of the coastal plain of marina di campo (elba island): preliminary results maurizio d’orefice1, luca foresi2 & roberto graciotti1 1ispra – servizio geologico d’italia, roma 2dipartimento di scienze geologiche, università di siena, siena  corresponding author: m. d’orefice <maurizio.dorefice@isprambiente.it> abstract: d’orefice m. et al., first recovery of marine quaternary deposits from geognostic boreholes of the coastal plain of marina di campo (elba island): preliminary results. (it issn 0394-3356, 2011). here we describe the preliminary results deriving from the analysis of the s2 geognostic borehole, which was drilled near the town of marina di campo (elba island). starting from a ground level at 1.29 m above the sea level, 25 m of quaternary deposits have been cored. these deposits are probably related to the last glacial-eustatic cycle. in particular, the lower part of the borehole is characterized by gravel and sandy-silt sediments typical of a fluvial environment. they settled during a low-stand phase of the last glacial maximum. these deposits are unconformably covered by coastal marine sands, sandy-silts and biocalcarenites (between -11.90 m and -5.20 m from the ground level) that were ascribed to the last sea level rise. the upper part of the geognostic survey is characterized by dark and plastic organic clays (from -5.20 m to the top). the basal clays are still marine (an age of 4.36÷3.81 ky cal bp has been obtained by radiocarbon dating), whereas those of the intermediate part are brackish (3.97÷3.45 ky cal bp). in the upper part we found clays that settled in a freshwater environment. riassunto: d’orefice m. et al., primi depositi quaternari marini rinvenuti nei sondaggi geognostici effettuati nella piana costiera di marina di campo (isola d’elba): risultati preliminari. (it issn 0394-3356, 2011). nella presente nota vengono descritti i risultati preliminari delle analisi condotte sulle carote prelevate nel sondaggio s2, realizzato alle spalle del centro abitato di marina di campo (isola d’elba). il sondaggio, spintosi sino alla profondità di -25,00 m dal piano campagna (p.c.), ha attraversato terreni quaternari in gran parte riferibili all’ultimo ciclo glacioeustatico. in particolare, la metà inferiore del sondaggio ha intercettato depositi ghiaiosi e sabbioso-limosi d’ambiente fluviale depostisi nel corso di una fase di basso stazionamento del livello marino attribuibile all’ultimo massimo glaciale. questi depositi passano superiormente (tra -11,90 e -5,20 m dal p.c.), con contatto netto erosivo, a sabbie, limi sabbiosi e biocalcareniti di chiara origine marina, attribuibili all’ultima risalita eustatica del livello del mare. la porzione superiore del sondaggio (da -5,20 m sino al p.c.) è composta da argille scure organiche plastiche. tali argille sono d’ambiente ancora marino nella loro parte basale (età radiometrica intorno ai 4,36÷3,81 ky cal bp), poi lagunare salmastro nel tratto intermedio (3,97÷3,45 ky cal bp) ed infine d’acqua dolce nella parte superiore. key words: quaternary geology, geognostic boreholes, marine deposits, marina di campo (elba island). parole chiave: geologia del quaternario, sondaggi geognostici, depositi marini, marina di campo (isola d’elba). in the small area of the elba island, the presence of a considerable variety of lithotypes, ranging from paleozoic to miocene, contrasts with the almost total absence of marine neogene and quaternary deposits (barberi et al., 1969). only few outcrops of uncertain marine origin are reported by mazzanti (1983) and centamore et al. (1988). yet, neogene and quaternary marine units extensively outcrop in the nearby island of pianosa (foresi et al., 2000; graciotti et al. 2002-2003) and along the tuscan coast (mazzanti, 1983). as a part of the geomorphological survey of the elba island (one project at a scale 1:50.000), six shallow continuous-core boreholes (< 30 m) were drilled in order to characterize the deposits of the main coastal plains. among them, four boreholes were drilled in the plain of marina di campo (central-southern elba), one near magazzini (central-northern elba) and the last one close to the locality of s. giovanni (central-northern elba). the sedimentological, micropaleontological (foraminifers and ostracods) and palynological analysis of many samples is ongoing. currently, 20 radiometric dating analyses were carried out using the technique of mass spectrometry (ams). other dating analyses are planned for the near future. the s2 borehole [25 m coring interval, from 1.29 m asl (above sea level) to 23.71 m bsl (below sea level)] is the most interesting. it is located just west of the coastal dune on which stands the marina di campo town, and records quaternary sediments of marine environment between 3.31 m bsl and 10.61 m bsl. for the first time, the presence of marine deposits of quaternary age is documented for certain on the elba island. the lower part of the borehole, from 25 m to 11.90 m bgl (below ground level) is mainly characterized by coarse gravel beds alternating with silty-clayey sands (fig. 1). the gravels are sub-angular, heterometric (ranging from some millimeters to a 29 31 30 maximum of 8 cm), heterogeneous (they derived from monzogranitic, porphyric and arenitic rocks), and are supported by a silty-sandy matrix. the gravel beds have an average thickness of about 150 cm, while the silty-clayey sands beds are 20÷230 cm thick. the finer levels are sometimes characterized by oxidized sandy laminae. no fossils were recovered in the lower interval of the borehole. starting from 11.90 m bgl, the coarse deposits of the lower part are unconformably covered by fine sands (80 cm thick). the contact is sharp and erosive. the sands pass up to matrix supported gravel beds (20 cm thick), rich of siliceous and poorly elaborate centimetric clasts. laminated silty sands with ochreous levels and clayey silty fine sands (120 cm total thickness) lay above the gravels. small fragments of mollusk, foraminifera and rare rests of others marine organism were found in the intervals 11.90 m ÷ 11.10 m and 10.50 m ÷ 9.70 m bgl. the interval between 9.70 m and 5.20 m bgl is composed of a sequence of highly fossiliferous sands, sandy silts and clayey sandy silts, alternating with three levels of biocalcarenites: the first between 9.70 m and 9.40 m, the second between 8.50 and 8.40 m and the third between 7.50 m and 6.30 m bgl. the micropaleontological analysis allowed to identify an abundant organic fraction consisting of mollusks, calcareous algae, foraminifers, ostracods, echinoids, sponge spicules, bryozoans and other minor components. at 5.20 m bgl, very dark gray plastic organic clays cover the fossiliferous sands and silts. the contact between the two units is sharp. the clays contain fossil assemblages which are significantly different from bottom to top. the interval from 5.20 m to 4.60 m bgl contain mollusks, echinoids, foraminifers, ostracods and calcareous algae typical of coastal marine environment. oligotypical assemblages of brackish environment are recorded from 4.60 m to 2.40 m bgl. they are composed of mollusks, ostracods, foraminifers (ammonia tepida and nonion sp.) and characeae oogonia. the clays in the interval 2.40 m÷1.10 m bgl contain only plant debris and rare characeae oogonia. this denotes a very shallow fresh water envirnoment. two radiometric dating analyses carried out on cerastoderma shells from two levels at 4.95 m and 4.30 m bgl have provided calibrated age of 4.36÷3.81 ky bp and 3.97÷3.45 ky bp, respectively. the upper part of the borehole is characterized by barren clayey-sandy silt in the interval 1.10÷0.50 m fig. 1 – synthetic log of the s2 borehole. log sintetico del sondaggio s2. m. d’orefice et al. 31 ms. received: testo ricevuto il bgl and by 0.50 m of landfill. on the basis of sedimentological characteristics and fossil content, eight main depositional intervals can be recognized starting from the stratigraphic top (ground level). they are summarized in table 1. in conclusion, preliminary data from the s2 borehole introduces new elements to reconstruct the evolution of the quaternary plain of marina di campo, with particular attention to the last glacialeustatic cycle. new chronological, paleontological and palynological constrains will be available once the analysis of the entire set of the s2 samples and the careful examination of the stratigraphy of the other five boreholes will be complete. references barberi f., dallan l., franzini m., giglia g., innocenti f., marinelli g., raggi g., squarci p., taffi l. & trevisan l. (1969) note illustrative della carta geologica d’italia alla scala 1:100.000. foglio 126 isola d’elba. min. ind. comm. art. serv. geol. d’it., 41 pp. centamore e., dramis f. & federici p. r. (1988) superfici di spianamento relitte e vicende morfoneotettoniche dell’isola d’elba. suppl. geogr. fis. dinam. quat., 1, 155-160. foresi l. m., cornamusini g., bossio a., ferrandini j., ferrandini m., mazzanti r., mazzei r. & salvatorini g. (2000) – the miocene sedimentary succession of the pianosa island, northern tyrrhenian sea. “evoluzione geologica e geodinamica dell’appennino” in memoria del prof. g. pialli. foligno, 16-18 febbraio 2000, 155-157. graciotti r., foresi l. & pantaloni m. (2004) lineamenti geomorfologici dell’isola di pianosa. soc. tosc. scien. nat. atti serie a. mazzanti r. (1983) il punto sul quaternario della fascia costiera e dell’arcipelago di toscana. boll. soc. geol. it., 102, 419-556. depth  (m bgl) litology and depositional environment relative sea level 0.0 ÷ 0.5 landfill 0.5 ÷ 1.1 sandy clayey silt typical of fresh water environment sea level high-stand 1.1 ÷ 2.4 very dark gray plastic organic clays deposited in a very shallow brackish or freshwater environment sea-level high-stand 2.4 ÷ 4.6 very dark gray plastic organic clays deposited around 3.97÷3.45 ky cal bp in a brackish environment sea-level high-stand 4.6 ÷ 5.2 very dark gray plastic organic clays deposited around 4.36÷3.81 ky cal bp in a shallow marine environment sea-level high-stand 5.2 ÷ 9.7 sand, silty sands and biocalcarenites of marine infralittoral environment transgressive phase of post-glacial sea level rise 9.7 ÷ 11.9 sands of very shallow marine environment, with levels of gravels and silty fine sands of fluvial environment transgressive phase of post-glacial sea level rise 11.9 ÷ 25.0 gravels and sands of fluvial environment seal level low-stand of the last glacial maximum tab. 1 – main lithotypes and depositional environments recorded by s2 boreholes, associated with relative sea level change. principali litotipi e ambienti deposizionali riscontrati nel sondaggio s2, associati alle variazioni relative del livello del mare. january 10, 2011 10 gennaio 2011 first recovery of marine quaternary deposits from ... amq abs tagliasacchi et al palcom 161-164.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 161 164 palaeoclimate changes in the afyon province, sw-turkey, during the middle-late pleistocene: signals from calcareous tufa pollen and stable isotope records ezher tagliasacchi 1, mine sezgül kayseri-özer 2 1 pamukkale university, geology engineering department, kınıklı, denizli, turkey 2 dokuz eylul university, institute of marine science and technology, haydar aliyev bul, i̇nciraltı-izmir, turkey corresponding author: e. tagliasacchi <egulbas@pau.edu.tr> abstract: the calcareous tufas of sarıkavak located in the northern part of ne-sw trending acıgöl graben in sw-turkey are investigated in detail. for this aim, various analyses (stable isotopes, u/th dating, palynology) have been carried out on samples obtained from both outcrops and drilling logs in and surrounding sarıkavak village. u/th dating shows that these carbonates precipitated from 400 ka up to 80 ka. preliminary pollen data, document climatic variability between mis 11 and mis 8 in the studied area. keywords: calcareous tufa, palynology, palaeoenvironment, palaeoclimate, afyon, sw-turkey 1. introduction terrestrial carbonates such as travertine and calcareous tufa are exposed in several depositional, climatic, and tectonic contexts throughout the world (chafetz & folk, 1984; pedley, 1990; ford & pedley, 1996; pentecost, 2005). their depositional, geochemical, isotopic and palynological signatures are very complex to interpret in terms of paleoenvironmental and palaeoclimatic changes (altunel & hancock, 1993; guo & riding, 1998; bertini et al., 2008; bertini et al., 2014; ricci et al., 2015; toker et al., 2015 and toker, 2017). the purpose of this study is to reveal the sedimentological and depositional processes as well as to approach the palaeoclimatic changes during the middlelate pleistocene in sarıkavak calcareous tufa located in afyon province, sw-turkey. 2. study area the acıgöl graben basin is located approximately 50 km northeast of denizli and southern afyon province in sw-turkey (fig. 1). it is an asymmetric graben, approximately 30 km long and 10 km wide, floored by the mesozoic-paleogene carbonate and ultramafic bedrocks (göktaş et al., 1989; şenel, 1997; konak & şenel, 2002). the upper miocene-pliocene deposits unconformably overlay molasse type deposits known as “çardak-dazkırı basin” and mainly consist of mudstonesandstone alternations and clay-rich limestone (göktaş et al., 1989; şenel, 1997; toker, 2009). the basin is bordered by ne-sw trending faults (i.e. the acıgöl fault in the south and the maymundağı fault in the north) which created a narrow corridor in which lake acıgöl developed during the pliocene (fig.1). the acıgöl graben basin started to form during the neotectonic period and deposits have been uplifted by activated older faults or newly generated younger faults (helvacı et al., 2013). travertine and calcareous tufa deposits overlay on the pliocene sediments and they are very well exposed in the örtülü and sarıkavak villages (fig. 1). 3. material and methods investigations on the sarıkavak calcareous tufa were divided into two steps: field work and laboratory analyses. during the field survey, we carried out facies description and samples collection from the non-marine carbonates and associated sediments. stable carbon and oxygen isotope measurements of the carbonates (sixty-three old tufa samples) for the palaeoenvironmental interpretation of these tufas were performed at the carbonate laboratory of stable isotopes, department of geoscience, university of arizona (usa). carbon and oxygen isotope analyses of bulk carbonate samples were carried out using the continuous flow technique (spötl and vennemann, 2003). 13c/12c and 18o/16o ratios were determined in co2 gases liberated by phosphoric acid using a finnigan delta plus xp mass spectrometer (thermo fisher scientific, bath, uk). u-th disequilibrium analyses were accomplished in low primary porosity twenty-three tufa samples. these samples were analyzed at the geotop research center of the university of quebec (montreal, canada). palynological analyses were conducted in two different laboratories. eight samples from the sarıkavak nonmarine carbonates were analyzed at the laboratory of palynology of the university of florence, italy, and the rest of them was analyzed at the laboratory of palynology of the department of the institute of marine science and technology, i̇zmir, turkey. https://doi.org/10.26382/aiqua.2018.aiquaconference 4. results in the sarıkavak tufas, seven lithofacies were distinguished. they are characterized by the good occurrence of mosses -included bryophytes, and macrophytes. however also other tufa lithofacies are well expressed by the occurrence of phytoclastic, oncolitic, stromatolitic, intra and extra clasts and sapropelitic tufas. all facies represent fluvial and fluvio-palustrine depositional systems (toker, 2017). ostracods and gastropods are the most abundant faunal remains. palynological analyses showed that palaeosol levels are more enriched in palynomorphs than bulk carbonate deposits. pollen of gymnosperms and angiosperms plus nonpollen palynomorphs are scarcely observed in travertine samples, whereas they are abundant in palaeosol samples. palynoflora defined in the palaeosol level is especially characterized by herbaceous taxa (i.e. poaceae, asteraceae asteroideae, artemisia, asteraceae cichorioideae, polygonum persicaria, geraniaceae and chenopodiaceae) but also includes trees taxa (i.e. quercus, castanea, cedrus and other pinaceae). nonpollen palynomorphs and other organic material were also abundantly recorded (fig. 2). pollen and other palynomorphs were detected in the bulk carbonate deposits in the sarıkavak tufas between the mis 8 (291±28ka) and mis 11 (359±21ka). the mis 11 interval is characterized by gymnosperm and angiosperm pollen (pinaceae-pinus spp., cedrus, castanea, oleaceae and chenopodiaceae). the pollen assemblage of mis 10 especially includes abies, pinaceae-pinus spp., oleaceae, fagaceae-quercus evergreen type, as 162 tagliasacchi e., kayseri-özer m.s. fig. 1 location of the study area. the satellite photo shows the sarıkavak and surrounding areas in sw-turkey. 163 teraceae asteroideae, artemisia and chenopodiaceae. palynomorph association of mis 9 was dominated by pinaceae-pinus sp. (haploxylon and diploxylon types), cedrus, pterocarya, oleaceae, fagaceae-quercus evergreen type and artemisia. these changes in the palynomorph association could be related to the climatic changes in the mis periods. δ18o values are in the range −10.83‰ to −7.49‰ vpdb while δ13c values vary from −1.63‰ to +1.5‰ vpdb. u/th dating of the sarıkavak calcareous tufas yielded 474 ka, 333 ka, 291 ka, 188 ka and 80 ka. stable isotope pattern is apparently coherent with the palynological-derived palaeoenvironental reconstruction. 5. discussion and conclusion this study permitted identification of seven tufa lithofacies which represent fluvial to fluvio-palustrine depositional systems. according to radiometric dating, carbonate precipitation occurred continuously across consecutive interglacial (e.g. mis 11 and mis 9) and glacial periods (e.g. mis 10 and mis 8) (fig. 2). the presence of palaeosols land debris flow supports main changes in atmospheric and edaphic humidity. precipitation of terrestrial carbonates started again to the edge of the graben fault (which confined the acıgöl graben, as fluvial tufa deposits), along mis 5, till ca. 80 ka. according to the stable isotopic measurements, δ13c values are between ‰ -1.6 and +1.5 ‰ while those of δ18o are between ‰ -7.4 and ‰ -10.8. the changes of δ18o values could be related to the evaporation in the depositional environment, while the less negative δ13c values could be interpreted as surface water mixing with the co2 transported from deep hydro thermal waters and decreasing the c isotope values. the spores and pollen records give some preliminary clues about the palaeovegetational and palaeoclimate of the region which is especially useful for a better interpretation of the δ13c stable isotopic fluctuations (i.e. arid vs less arid/humid conditions). acknowledgement this study is financially supported by tubi̇tak (the scientific and technological research council of turkey) (project no. 115y493) and pamukkale university scientific research project unit (project no. 2014hzl010). the authors warmly thank to reviewers for the helpful comments and suggestions. references arenas-abad c., vazquez-urbez m., pardo-tirapu g., sancho-marcen c. (2010) fluvial and associated carbonate deposits. in: carbonates in continental settings: facies, environments, and processes (eds a.m. alonso zarza and l.h. taner), dev. sedimentology, 61, 133-175. bertini a., minissale a., ricci m. (2008) use of quaternary travertines of central-southern italy as archives of paleoclimate, paleohydrology and neotectonics, il quaternario, 21 (1b), 99-112. bertini a., minissale a., ricci m. (2014) palynological approach in upper quaternary terrestrial carbonates of central italy: anything but a “mission impossible, sedimentology, 61, 200-220. chafetz h.s., folk r.l. (1984) travertines: depositional morphology and the bacterially constructed constituents. journal sedimentary petrology, 54, 1, 289 316. göktas f., çakmakoğlu a., tan e., sütçü y.f., sarıkaya h. (1989) çivrilçardak arasının jeolojisi. (the geology between çivril-çardak region). mineral research and exploration institute of turkey (mta), report no. 8701, pp. 109. (in turkish with english abstract) guo l., riding r. (1998) hot-spring travertine facies and sequences, late pleistocene rapolano terme, italy. sedimentology, 45, 163-180. helvacı c., alçiçek m.c., gündogan i., gemici ü. (2013) pollen and stable isotopes palaeoclimate record, afyon province fig. 2 palynomorph assemblage in the interval between mis 11 and mis 8. tectono sedimentary development and palaeoenvironmental changes in the acıgöl shallow perennial playa-lake basin, sw anatolia, turkey. turkish journal of earth sciences, 22, 173-190. konak n., şenel m. (2002) geological map of turkey in 1/500.000 scale: denizli sheet. mineral research and exploration institute of turkey (mta) publications. ricci m., bertini a., capezzuoli e., horvatinčić n., andrews j.e., fauquette s., fedi m. (2015) palynological investigation of a late quaternary calcareous tufa and travertine deposits: the case study of bagnoli in the valdelsa basin (tuscany, central italy). review of palaeobotany and palynology, 218, 184-197. spötl c., vennemann t.w. (2003) continuous-flow irms analysis of carbonate minerals. rapid communications in mass spectrometry, 17, 10041006. şenel m. (1997) geological maps of turkey in 1:100.000 scale: denizli k9 sheet. mineral research and exploration directorate of turkey, ankara, pp. 17. toker e. (2009) the investigation of tectonosedimentary evolution of the tertiary deposits in the north of acıgöl çardak (denizli) graben basin). phd thesis, pp. 242. (in turkish with english abstract, unpublished) toker e. (2017) quaternary fluvials tufas of sarıkavak area, southwestern turkey: facies and depositional systems. quaternary international, nonmarine carbonates, special issue, 437, 37-50. toker e., kayseri-özer m.s., özkul m., kele s. (2015) depositional system and palaeoclimatic interpretations of middle to late pleistocene travertines: kocabaş, denizli, sw turkey. sedimentology, 62 (5), 1360-1383. 164 tagliasacchi e., kayseri-özer m.s. ms. received: may 2, 2018 final text received: may 22, 2018 available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 69 71 pollen evidence of vegetation changes and land use on the tropea promontory (calabria, italy) during prehistory halinka di lorenzo, elda russo ermolli dipartimento di scienze della terra, dell'ambiente e delle risorse, università di napoli federico ii, napoli, italy corresponding author: h. di lorenzo <halinka.dilorenzo@unina.it> abstract: pollen analysis was undertaken on a sediment core drilled at the top of the tropea promontory (calabria), an area rich in archaeological evidence from the eneolithic up to the iron age. human impact is clearly detected in the basal portion of the core through deforestation, fires, crops and pasturage activities. the anthropic pressure seems to generally reduce around the core site in the second half of the core, when a significant forest recover is recorded. these local vegetation changes and land use could be ascribed to both a gradual closure of the marsh and a possible abandonment of this area for pastoral and agricultural practices. keywords: palynology, microcharcoals, deforestation, human impact, late holocene 1. introduction archeological surveys of the last years have witnessed a diffuse human presence in the tropea promontory during prehistoric times (pacciarelli, 2004, 2011; lo torto, et al., 2011; jung, et al., 2015). in order to better define the impact that humans exerted on this territory during prehistory, palynological investigations were realized with the main aim of distinguishing the natural and anthropogenic forcing in the evolution of the past landscapes. the results here presented increase the knowledge, already acquired in this area (russo ermolli et al., 2018), on the complex human environment interactions in a key region for the italian prehistory. 2. material and methods a sediment core was drilled at 555 m a.s.l. on top of the tropea promontory, a site rich in archeological evidence dated from the eneolithic up to the iron age. the site was selected on the basis of a previous study (lo torto et al., 2011) highlighting the occurrence of buried layers with eneolithic pottery in the passo murato locality. the coring, realized in 2015 with a small piston corer, intercepted a peat deposit (from 1.10 to 2.40 m depth), covering the pre-quaternary substratum, whose base likely corresponds to the levels analyzed by lo torto et al. (2011). pollen analysis was undertaken on 21 peat samples collected from the core each 5 cm, from 110 to 235 m depth. chemical (hcl 20%, hf 40%, hot hcl 10%, acetolysis) and physical (10 μm ≤ sieving ≤ 200 μm, zncl2 floating) treatments were used to concentrate pollen grains in the residue. slides were mounted in glycerin to permit pollen motion and facilitate taxonomical determination. determinations and counts were carried out under a light microscope at 500x and 1000x magnification, with the support of pollen atlases (reille, 1992-1995; beug, 2015) and reference pollen material. 3. results almost all analyzed samples resulted rich in well preserved pollen grains and only 4 samples resulted poor; 74 taxa were recognized. a synthetic diagram was realized (fig. 1) by selecting taxa, or groups of taxa, among the most representative of man impact. from the left-hand side of the diagram, some selected trees are shown: quercus ilex (mediterranean forest), quercus (deciduous forest) and alnus (floodplain forest), followed by microcharcoals. the arboral pollen (ap) curve indicates the rate of the forest cover. it is assumed that ap percentages over 70% are indicative of a forested landscape while percentages below 40% indicate open environments (favre, et al., 2008). intermediate percentages (from 40 to 70%) indicate a patchy landscape with open spaces and scattered forested areas. the herbaceous taxa are dominated by the poaceae family. the main anthropogenic indicators are displayed with different percentage scales, depending on their amounts. cyperaceae (marsh plants) are listed at the extreme right of the diagram. 4. discussion and conclusion in the basal part of the diagram, high amounts of microcharcoals, recorded in concomitance with the lowering of arboreal pollen percentages, attest to the use of anthropogenic fires to open the landscape for agricultural practices (cereals) and animal husbandry, which is well testified by the high amounts of fungal spores, indicative of pasturage (cugny et al., 2010; ejarque et al., 2011). starting from 165 cm depth, a decrease in the fire practice is coupled with the recovery of the forest cover and an increase in the marsh plants. these vegetation https://doi.org/10.26382/aiqua.2018.aiquaconference changes could indicate both a contraction of the marsh and a partial abandonment of the area. some cereal crops were still present and a peak of trifolium opens up interesting hypothesis on the occurrence of forage crops (miras et al., 2018). another important change is recorded from 130 cm depth, when alnus markedly increases in concurrence with the decrease in cyperaceae. these results could indicate a further contraction and final closure of the marsh, which led to the rapid development of an alder forest on the wet soils. evidence of abandonment is clearly recorded in the last levels even if the topmost sample seems to suggest a possible recolonization, with a slight forest decline and cereal increase. the reconstructed history of vegetation and land use changes on the tropea promontory certainly needs further investigation especially concerning their connection to the presence of prehistoric communities. the detailed dating of the core, which is in progress, will allow such connections to be established. with this perspective, the passo murato core represents an important sedimentary archive that enriches the knowledge of an important territory widely exploited by prehistoric human communities. references anzidei a.p., bulgarelli g.m., catalano p., cerilli e., gallotti r., lemorini c., milli s., palombo m.r., pantano w., santucci e. (2012) ongoing research at the late middle pleistocene site of la polledrara di cecanibbio (central italy), with emphasis on human-elephant relationships. quaternary international, 255, 171-187. beug h.j. (2015) leitfaden der pollenbestimmung für mitteleuropa und angrenzende gebiete. verlag dr. friedrich pfeil, munchen. cugny c., mazier f., galop d. (2010) modern and fossil non-pollen palynomorphs from the basque mountains (western pyrenees, france): the use of coprophilous fungi to reconstruct pastoral activity. vegetation history and archaeobotany, 19, 391408. ejarque a., miras y., riera s. (2011) pollen and nonpollen palynomorph indicators of vegetation and highland grazing activities obtained from modern surface and dung datasets in the eastern pyrenees. review of palaeobotany and palynology, 167, 123-139. favre e., escarguel g., suc j.p., vidal g., thévenod l. (2008) a contribution to deciphering the meaning of ap/nap with respect to vegetation cover. review of palaeobotany and palynology, 148, 13-35. jung r., pacciarelli m., zach b., klee m., thanheiser u. (2015) punta di zambrone (calabria) a bronze age harbour site. first preliminary report on the recent bronze age (2011-2012 camapaigns). archeologia austriaca, band 99/2015, 53-110. lo torto a., rombolà c., rombolà f., starpoli f. (2011) il giacimento di passo murato: scoperta, rilevamento, recupero e segnalazione. origini, 33 (n.s.v.), 293-294. miras y., ejarque a., barbier pain d., corbineau r., ledger m., riera mora s., garreau a., voldoire o., allain e., mangado llach j., sànchez de la torre m., màrtinez grau h., bergadà m.m., smith s. j. (2018) advancing the analysis of past human/plant relationships: methodological improvements of artefact pollen washes. archaeometry. doi: 10.1111/arcm.12375 pacciarelli m. (2004) la prima età del ferro in calabria. atti della xxxvii riunione scientifica dell’istituto italiano di preistoria e protostoria, vol. i (29 settembre-4 ottobre 2002), 447-475. 70 di lorenzo h., russo ermolli e. fig. 1 synthetic pollen diagram of passo murato core 71 pacciarelli m. (2011) l’eneolitico della calabria tirrenica: nuovi dati sull’articolazione cronoculturale. origini 33, n.s.v, 249-302. russo ermolli e., ruello m.r., cicala l., di lorenzo h., molisso f., pacciarelli m., (2018) an 8300-yr record of environmental and cultural&#13; changes in the sant’eufemia plain (calabria, italy). quaternary international. doi:10.1016/j.quaint.2018.01.033 reille m. (1992-1995) pollen et spores d’europe et d’afrique du nord. laboratoire de botanique historique et palynologie, ura cnrs 1152, marseille. pollen evidence of human impact in calabria (italy) ms. received: may 10, 2018 final text received: may 19, 2018 72 amq abs divito et al tepro 205-208.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 205 208 the vesuvius pomici di avellino plinian eruption and related phenomena: effects on the bronze age landscape of campania region (southern italy) mauro antonio di vito1, pierfrancesco talamo 2, ilaria rucco 1, halinka di lorenzo 3 1 istituto nazionale di geofisica e vulcanologia, sezione di napoli osservatorio vesuviano, napoli, italy 2 parco archeologico dei campi flegrei, mibact, napoli, italy 3 distar, università degli studi di napoli, italy corresponding author: m.a. di vito <mauro.divito@ingv.it> abstract: the vesuvian pomici di avellino eruption affected an area densely inhabited by early bronze age human communities and resulted in the long term abandonment of an extensive zone surrounding the volcano. the study of geological and archaeological sequences have yielded an understanding of the eruption local effects and of their duration. the territory was rapidly abandoned during the eruption. only few settlements were found of phases 1 and 2 of the middle bronze age in most of the area affected by the eruption. we interpret this as due to diffuse phenomena of remobilization of the erupted pyroclastics, generating long lasting alluvial processes. a significant resettlement of the territory occurred only hundreds of years after the eruption, during phase 3 of the middle bronze age. keywords: plinian eruption, volcanoclastic mass flow, vesuvius, bronze age, eruption impact 1. introduction plinian eruptions are among the most dangerous natural phenomena for human life and the environment, characterized by very energetic and sustained explosive phases generating convective plumes and whose instability and collapse can generate pyroclastic density currents. they also produce secondary phenomena, not directly connected to the eruption itself, like, volcaniclastic mass flows (lahars) generated by the remobilization of pyroclastic deposits that can occur in areas very far from the vent and even centuries after an eruption. the pomici di avellino eruption (hereafter pda, 3,945 ± 10 cal yr bp) is one of the four plinian eruptions of vesuvius, considered one of the most explosive holocene events in the mediterranean area. the eruption and related phenomena affected a wide and densely inhabited area in the early bronze age (hereafter eba) (di vito et al., 2018 and references therein). in this paper we present the results of volcanological and archaeological investigations concerning the impact of the pda eruption and related volcanoclastic mass flows, in order to reconstruct the human abandonment and resettlement dynamics of the campania region, during the early and middle bronze age. 2. material and methods combined volcanological and archaeological studies has permitted to understand the relationship between human settlements and natural hazards (di vito et al., 2009; di lorenzo et al., 2013; de vita et al., 2013; romano et al., 2013; vingiani et al., 2017; di vito et al., 2018). the integration of volcanological and archaeological data from literature and the analysis of sequences in recent excavations permitted the creation of a dataset with information on more than 300 sites in the campanian plain and in the surrounding apennine valleys. particular attention has been payed to the emplacement mechanisms of volcanic and volcanoclastic deposits, in order to analyse the effects of the eruption and of the secondary environmental processes on the palma campania culture settlements pre-existing to the pda eruption. the integration of stratigraphic and archaeologic investigations also permitted to evaluate the time of reoccupation of the teritory. 3. results the campanian plain, and especially the lowlands surrounding vesuvius, was densely inhabited by communities of farmers and pastoralists belonging to the eba palma campania culture. all of the most important remains of this culture have come from the numerous villages buried by variable deposits of the pda eruption (fig. 1). some of these settlements were of considerable extent. in some places there are evidence of attempts of resettlement soon after eruption (green dots in fig. 1). the pda eruption occurred during the eba and in particular between the end of the twentieth and the beginning of the nineteenth century bc (passariello et al., 2009, 2010; sevink et al., 2011). according to di vito et al. (2009), the eruption can be divided into five eruption units (eus) emplaced during three phases: opening, plinian and phreatomagmatic. the opening phase was characterized by a low eruption column that emplaced thin ash layers (eu1) distributed toward the east of the vent; the plinian phase generated a 23-to-31 km high eruption column, that emplaced widely distributed pumice fallouts deposits (eu2, https://doi.org/10.26382/aiqua.2018.aiquaconference eu3 and eu4 – fig. 1), and ended with a caldera collapse. the last phreatomagmatic phase was dominated by pulsating phreatomagmatic explosions that produced both pyroclastic density currents and minor fallout deposits (eu5 – fig. 1). these deposits can be divided in four subunits (eu5a-d), that correspond to at least four explosive episodes, separated by short pauses during the eruption. human and animal footprints and hoofprints have been found at different heights in eu5 unit and testify to some migration episodes during the final phases of the eruption (di vito et al., 2009). the eruption caused also a general hydrogeological destabilization of the territory, which generated lahars, debris flows and alluvial processes in a wide area. in archaeological excavations and in natural exposures, the presence of soils or unconformities between the primary and secondary deposits, or within the secondary deposit has been used to distinguish among syneruptive (according to the definition of sulpizio et al., 2006) and intereruptive lahars, debris flows and alluvial deposits. in fig. 2 we report only the sites containing syneruptive debris flow deposits. they are composed almost exclusively of fragments from pda eruption. 4. discussion and conclusions the analysis carried out in an area of about 3.000 km2 and on at least 300 investigated sites shows that before the pda eruption campanian plain was more or less occupied by palma campania facies settlements. the first effect of the eruption is that the following facies, that is the proto apennine facies (middle bronze age 1 and 2), is almost completely missing in the area, covered by primary and secondary deposits; instead there are evidence of a continuity of human presence, with the two archaeological facies, in few sites far from the areas interested by the main deposition of the pda primary and secondary products (fig. 2) or along the coastal area of the gulf of naples, where an increase in the settled sites is seen. therefore, from the period immediately following the pda eruption and for at least a couple of centuries, the population declined in almost the entire area affected by the eruption and related phenomena. this seems to have occurred regardless of the distance from the vent and the local impact of the eruption phenomena on the environment and human settlements. this population decline might have also been caused by adverse 206 fig. 1 early bronze age settlements. red dots indicate the sites existing before the pomici di avellino eruption; green dots indicate those sites in which there are also evidences of attempts of resettlement soon after the eruption. the total distribution of the pomici di avellino deposits is reported for reference: pdc deposits in purple; fallout deposits in white. in the inset the total distribution of the pomici di avellino deposits. (modified after di vito et al., 2018). di vito m.a. et al. 207 climatic conditions, which soon after the eruption increased the area's hydrogeological instability, with generation of huge, frequent and widely distributed lahars (fig. 2, see distribution of grey diamonds). this period was followed by a climate deterioration that would not have favored agriculture in the zone (zanchetta et al., submitted). furthermore, all along the coastal area, even though the crisis triggered deep changes, it did not lead to a total de-structuring of the territory and, after a short period, a new equilibrium seems to have been reached. a significant resettlement of the territory occurred only hundreds of years after the pda eruption, during phase 3 of the middle bronze age (apennine facies), during a period of favourable environmental conditions. acknowledgments the presented study has benefited from the financial support of the presidenza del consiglio dei ministri dipartimento della protezione civile dpc-ingv project ob. 4 task 1. the authors are grateful to the archaeological superintendences of campania for allowing the analyses of sequences in excavations. references de vita s., di vito m.a., gialanella c., sansivero f. (2013) the impact of the ischia porto tephra eruption (italy) on the greek colony of pthekoussai. quaternary international, 303, 142-152. di lorenzo h., di vito m.a., talamo p., bishop j., castaldo n., de vita s., nave r., pacciarelli m. (2013) the impact of the pomici di avellino plinian eruption of vesuvius on early and middle bronze age human settlement in campania (southern italy). tagungen des landesmuseums für vorgeschichte halle, 9, 253-265. di vito m.a., talamo p., de vita s., rucco i., zanchetta g., cesarano m. (2018) dynamics and effects of the vesuvius pomici di avellino plinian eruption and related phenomena on the bronze age landscape of campania region (southern italy). quaternary international. doi: 10.1016/j.quaint.2018.03.021 di vito m.a., zanella e., gurioli l., lanza r., sulpizio r., bishop j., tema e., boenzi g., laforgia e. (2009) the afragola settlement near vesuvius, fig. 2 location of the middle bronze age 1, 2 (protoapennine 1 and 2 facies, blue dots) and 3 sites (apennine facies, red dots). the total distribution of the pomici di avellino deposits is reported for reference, as in fig 1. grey diamonds indicate the sites at which the syneruptive volcanoclastic mass flow deposits have been recognized. the total distribution of the pomici di avellino deposits is reported for reference, as in fig.1 (modified after di vito et al., 2018) effects of the human settlements of the pomici di avellino eruption italy: the destruction and abandonment of a bronze age village revealed by archaeology, volcanology and rock-magnetism. earth and planetary science letters, 277, 408-421. passariello i., albore livadie c., talamo p., lubritto c., d'onofrio a., terrasi f. (2009) 14c chronology of avellino pumices eruption and timing of human reoccupation of the devastated region. radiocarbon, 51 (02), 803-816. passariello i., lubritto c., d'onofrio a., guan y., terrasi f. (2010) the somma-vesuvius complex and the phlaegrean fields caldera: new chronological data of several eruptions of the copper-middle bronze age period. nuclear instruments and methods in physics research b, 268, 1008-1012. romano p., di vito m.a., giampaola d., cinque a., bartoli c., boenzi g., detta f., di marco m., giglio m., iodice s., liuzza v., ruello m.r., schiano di cola c. (2013) intersection of exogenous, endogenous and anthropogenic factors in the holocene landscape: a study of the naples coastline during the last 6000 years. quaternary international, 303, 107-119. sevink j., van bergen m.j., van der plicht j., feiken h., anastasia c., huizinga h. (2011) robust date for the bronze age avellino eruption (sommavesuvius): 3945 ±10 calbp (1995 ±10 calbc). quaternary science review, 30 (9), 1035-1046. sulpizio r., zanchetta g., demi f., di vito m.a., pareschi m.t., santacroce r. (2006) the holocene syneruptive volcaniclastic debris flows in the vesuvian area: geological data as a guide for hazard assessment. in: siebe, c., macias, j.l., aguirre-diaz, g.j. (eds.). neogene-quaternary continental margin volcanism: a perspective from mexico, special paper, gsa, 402, 203-221. vingiani s., minieri l., albore livadie c., di vito m.a., terribile f. (2017) pedological investigation of an early bronze age site in southern italy. geoarchaeology, 33, 193-217. zanchetta g., bini m., di vito m.a., sulpizio r., sadori l. (submitted) tephrostratigraphy and synchronization of climatic archives in the central mediterranean during the bronze age. quaternary international. 208 di vito m.a. et al. ms. received: may 7, 2018 final text received: may 21, 2018 amq abs marchegiano et al palcom 147-150.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 147 150 rapid late pleistocene climate change reconstructed from a lacustrine ostracod record in central italy (lake trasimeno, umbria): preliminary results marta marchegiano 1, david j. horne 2, elsa gliozzi 3, daniel ariztegui1 1 department of earth sciences, university of geneva, geneva, switzerland 2 school of geography, queen mary university of london, london, uk 3 department of science, university roma tre, roma, italy corresponding author: m. marchegiano <marta.marchegiano@unige.ch> abstract: an 8.59 m long sediment core was retrieved from lake trasimeno (central italy) with the aim of performing a palaeoclimatic and palaeoenvironmental reconstruction. in this study we present, for the first time in central italy, a quantitative palaeotemperatures reconstruction based on ostracod assemblages. the mean winter (january) and summer (july) palaeotemperatures were estimated from 44,000 to 9,000 cal yr bp by using the mutual ostracod temperature range (motr) method. of the total of 19 ostracod species recovered, 13 of them were used as reliable palaeotemperature proxies on the base of their living temperature ranges. keywords: palaeotemperatures, palaeoclimatology, ostracoda, central mediterranean, quaternary 1. introduction the late quaternary climate has been affected by numerous and rapid fluctuations and different techniques have been developed to reveal their extent and associated effects on the environment. here we present for the first time the application of the mutual ostracod temperature range (motr) method (horne, 2007) on an 8.59 m long sediment core from lake trasimeno (central italy) with the aim of reconstruct the palaeotemperature variations in central italy. the provisional age model proposed by marchegiano et al. (2017a) suggests the co1320 trasimeno sediment core covers the last 47,000 cal yr bp. the motr analysis was performed within the interval from 44,000 to 9,000 cal yr bp. this period encompassed a long mild period (mis 3), followed by a colder one (mis 2) and ended with the beginning of the holocene, characterised by the abrupt restoration of warmer conditions. the mis 3 and 2 enclosed high-frequency climate variations characterised by warmer (interstadial) and colder (stadial) periods (abrantes et al., 2012). these features were recognized for the first time in the ice-core record from greenland (grootes & stuiver, 1997; johnsen et al., 1992) and subsequently documented in climate records all over the world (voelker, 2002). in central italy, several palynological studies (summarized in fletcher et al., 2010), revealed that the greenland interstadials (gi) were characterised by relatively humid conditions, whereas dry ones prevailed during greenland stadials (gs). this trend has been further confirmed at lake trasimeno (43°09’n; 12°06’e, umbria region, central italy) (fig. 1) by the repeated changes of the ostracod assemblages that suggested frequent lake level variations that mirrored the alternation of dry and humid phases (marchegiano et al. 2017a). due to its very shallow depth (maximum depth of 6 m), its smooth bathymetry (ludovisi et al., 2005) and its endorheic nature, lake trasimeno revealed to be particularly suitable to detect the changes in the lacustrine environment driven by climate, since its hydrological system strictly depends on climatically-governed precipitation/evaporation changes (dragoni et al., 2012). the continuous presence of fossil ostracods throughout the entire succession (marchegano et al., 2017a), allowed to fruitfully apply the motr method fig. 1 map of lake trasimeno showing the location of core co1320. legend: a. natural catchment area; b. artificially-joined basins; c. sluice gates of the artificially-joined channels (modified from marchegiano et al., 2017). https://doi.org/10.26382/aiqua.2018.aiquaconference along the sediment core, trying to depict, for the first time, the palaeotemperature variations based on ostracods. in fact, until today, only few continental records provided high-resolution analyses of late quaternary climatic changes, mainly based on pollen [e.g. lago di lagaccione (magri & sadori 1999), lago di vico (magri 1999, magri & parra 2002), lago di albano (ariztegui et al., 2001), valle di castiglione (magri, 1994), lago di monticchio (allen et al., 1999), lake ohrid (wagner et al., 2017)]. 2. methods the motr is a non-analogue method (horne, 2007) for reconstructing palaeotemperature using freshwater fossil ostracod assemblages, based on the species still living today with a known climatic distribution. the temperature ranges, which enclose all the living records of the species, are determined by fitting worldclim database (version1.3) (hijmans et al., 2001) to the mapped coordinate points of the species’ distribution and are expressed in terms of the maximum and minimum values of july and january temperature ranges. the temperature reconstruction for a given interval is provided by the mutual temperature range of all the species in the fossil assemblage. (i.e. the t interval in which they could have co-existed fig 2.). 3. results a total of three hundred and fifty samples were analysed to perform the motr method in the trasimeno sedimentary core. the ostracod analyses (marchegiano et al., 2017a) enabled recognition of 19 different species of ostracods referable to 15 genera: cyprideis torosa, candona angulata, candona neglecta, candona candida, heterocypris incongruens, cytheromorpha fuscata, sarscypridopsis aculeata, heterocypris salina, ilyocypris sp., eucypris mareotica, darwinula stevensoni, limnocythere inopinata, limnocythere blankenbergensis, potamocypris paludum, trajancypris serrata, amnicythere sp., herpetocypris helenae, cypridopsis vidua, plesiocypridopsis newtoni. among all of the recovered species, cyprideis torosa was not taken into account because is a typically brackish water species (although it occurs sometimes in freshwater) while the motr method is developed only for freshwater species. other species were also excluded: amnicythere sp. and ilyocypris sp., for reasons of taxonomic uncertainty, and trajancypris serrata, potamocypris paludum and herpetocypris helenae, which are still not calibrated. the temperature ranges were calculated for all the samples from 7.4 to 3.1 m depth in the co1320 trasimeno core to obtain the palaeotemperature variations during the whole sequence, represented by reconstructed palaeotemperature ranges to which maxima and minima curves can be fitted. 4. discussion and conclusions although the mutual ostracod temperature range method has been frequently applied to infer past climate conditions (horne, 2007; horne et al., 2012; pint et al., 2015; cosentino et al. 2017; benvenuti et al. 2017), in this contribution it was used, for the first time, to reconstruct a palaeotemperature curve similar to those derived from other usual proxies (e.g. isotopes, pollen and beetles (inter alia atkinson et al., 1987-1986; allen et al., 1999; pross et al., 2000; pross & klotz, 2002). notwithstanding uncertainties regarding where (within the reconstructed ranges) the actual temperatures were located, a preliminary inspection of the motr results suggests rapid temperature changes in central italy in the interval from 44,000 to 9,000 cal yr bp. in order to compare the global temperature changes of this period with the ones that affect central italy, the motr-derived curves have been compared with the greenland isotopic palaeotemperature reconstruction (ngrip-members, 2004). despite limitations of the use of a provisional age-depth model, the january 148 marchegiano m. et al. fig. 2 example of the application of the motr method on sample 374 of the co1320. 149 and july temperature curves show a remarkable correspondence with features of the ngrip-record, demonstrating their ability to record the millennial climate variations. the trasimeno motr reconstruction also reveals the possible occurrence of rapid climate changes, which could be considered equivalent to those observed at monticchio lake by allen et al. 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(2000) peconstructing palaeotemperatures from the early and middle pleistocene using the mutual climatic range method based on plant fossils. quateranry science reviews, 19, 1785-1799. wagner b., wilke t., francke a., albrecht c., baumgarten h., bertini a., combourieu-nebout n., cvetkoska a., d'addabbo m., donders t. h., föller k., giaccio b., grazhdani a., hauffe t., holtvoeth j., joannin s., jovanovska e., just j., kouli k., koutsodendris a., krastel s., lacey j. h., leicher n., leng m. j., levkov z., lindhorst k., masi a., mercuri a. m., nomade s., nowaczyk n., panagiotopoulos k., peyron o., reed j. m., regattieri e., sadori l., sagnotti l., stelbrink b., sulpizio r., tofilovska s., torri p., vogel h., wagner t., wagner-cremer f., wolff g. a., wonik t., zanchetta g., zhang x. s. (2017) the environmental and evolutionary history of lake ohrid (fyrom/albania): interim results from the scopsco deep drilling project. biogeosciences, 14, 2033-2054. 150 marchegiano m. et al. ms. received: may 3, 2018 final text received: may 24, 2018 available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 17 21 morphodynamics of coastal areas represented in the new geomorphologic map of italy: draw the landforms of the past to outline the future alessandro chelli 1 , domenico aringoli 2 , pietro p.c. aucelli 3 , maurizio a. baldassarre 4 , piero bellotti 4 , monica bini 5 , sara biolchi 6 , sara bontempi 4 , pierluigi brandolini 7 , lina davoli 4 , giacomo deiana 8 , sandro de muro 9 , stefano devoto 6 , gianluigi di paola 10 , carlo donadio 11 , paola fago 12 , marco ferrari 7 , stefano furlani 6 , angelo ibba 9 , elvidio lupia palmieri 4 , antonella marsico 12 , giuseppe mastronuzzi 12 , rita t. melis 8 , maurilio milella 12 , luigi mucerino 7 , olivia nesci 13 , paolo e. orrú 8 , valeria panizza 14 , micla pennetta 11 , daniela piacentini 13 , arcangelo piscitelli 12 , nicola pusceddu 7 , rossana raffi 4 , carmen m. rosskopf 10 , paolo sansó 15 , corrado stanislao 11 , claudia tarragoni 4 , alessio valente 16 1 dip. di scienze chimiche, della vita e della sostenibilità ambientale, università di parma, parma, italy 2 scuola di scienze e tecnologie, sezione di geologia, università degli studi di camerino, camerino, italy 3 dip. di scienze e tecnologie, università degli studi di napoli parthenope, napoli, italy 4 dip. di scienze della terra, università “sapienza”, roma, italy 5 dip. di scienze della terra, università di pisa, pisa, italy 6 dip. di matematica e geoscienze, università degli studi di trieste, trieste, italy 7 dip. di scienze della terra, dell’ambiente e della vita, università degli studi di genova, genova, italy 8 dip. di scienze chimiche e geologiche, università di cagliari, cagliari, italy 9 oss. coste e ambiente naturale sottomarino, dip. di scienze chimiche e geologiche, università di cagliari, cagliari, italy 10 dip. di bioscienze e territorio, università degli studi del molise, pesche (is), italy 11 dip. di scienze della terra, dell’ambiente e delle risorse, università degli studi di napoli federico ii, napoli , italy 12 dip. di scienze della terra e geoambientali, università degli studi di bari “aldo moro”, bari, italy 13 dip. di scienze pure ed applicate, università di urbino, urbino (pu), italy 14 dip. di storia, scienze dell’uomo e della formazione, università di sassari, sassari, italy 15 dip. scienze e tecnologie biologiche e ambientali, università del salento, lecce, italy 16 dip. di scienze e tecnologie, università del sannio, benevento, italy corresponding author: a. chelli <alessandro.chelli@unipr.it> abstract: in the framework of the revision of italian geomorphological legend (carg project) published in 1994 by the national geological service, the aigeo-working group coastal morphodynamic (wgcm) dealt with the revision of the legend concerning the landforms of the coast. the aims of the work were the updating of the symbology on the basis of the post-1994 results in the geomorphological researches and creating a legend more vocated to the solution of the problems of applied geomorphology and more suitable to be managed in gis environment. the wgcm started from the critical analysis of the classifications of coastal landforms proposed during the last century and it continued through a scientific discussion on the work that the members of the group performed by means of 12 case studies in which a correlation between landforms, processes and, dynamics was made. the geomorphological legend proposed by the wgcm has to be considered as a starting point and a work in progress. it remains, indeed, open so that new data can be added and updated as required. besides, the wgcm tried to contribute to the morphodynamic classification of the coasts around the mediterranean basin. keywords: coastal dynamics, coastal geomorphology, geomorphological mapping, mediterranean coast 1. introduction the geomorphological map is the basic tool for the representation of landforms of earth topographic relief and, as such, is currently the document present in most of the activities of environmental planning carried out in italy at the various institutional levels, from the national to the municipal one, with particular reference to the evaluation of geomorphological hazards and the mitigation of the associated risks. the geomorphological mapping in italy has reached high levels of scientific value in the description and analysis of the landscape and in returning correct territorial data from the dimensional point of view, as well as providing the necessary geomorphological information useful for the applied purposes in different scientific sectors, such as hydraulics, forestry sciences, agronomy, environmental engineering, architecture, landscape ecology, etc. besides, thanks to the capability to represent the state of activity of landforms, and of associated processes of course, the geomorphological mapping is the https://doi.org/10.26382/aiqua.2018.aiquaconference primary tool to provide a dynamic view of the landscape. the legend of the geomorphological map of italy (carg project) published in 1994 by the national geological service (brancaccio et al., 1994) represented the first document that summarized the different approaches to the representation of landforms that were developed in italy by different schools, since the sixties of the last century. in fact, the current system of italian geomorphological mapping has its origin from the works of authors such as castiglioni (1964) and panizza (1966) who have also worked in synergy with international groups and from the experience shared through workshops of informal working groups constituted by italian geomorphologists (gsueg, 1978; grg, 1982; gngfg, 1986; 1987; 1993; 1995). since 2015, the italian geomorphologists community has started, as part of the works of the italian association of physical geography and geomorphology (aigeo), the revision of the 1994’ legend, thanks to the work of the working groups (wgs) born within the association. the wg coastal morphodynamic (wgcm), established by aigeo in 2013, dealt with the revision of the legend concerning the landforms of the coast, dealing with the landforms of wave-climate and eolian origin, these latters having, in the morphoclimatic system that characterizes the italian peninsula, the best expressions in correspondence of the morphosedimentary dunebeach systems. the aims of the wgcm were: 1) to implement and update the symbology by introducing the results of the last 25 years of geomorphological research, 2) creating a legend and then a geomorphological map, with a 18 fig. 1 case studies: 1) bonassolalevanto rocky coast and embayed beach; 2) tellaro rocky coast; 3) the franco promontory and the campese bay; 4) isola dei gabbiani tombolo; 5) the coastal area of torre san giovanni capo san marco; 6) the tiber river delta; 7) littoral of the garigliano river mouth; 8) the la vota paralic system; 9) the roca sant’andrea coast; 10) the northen sector of the molise coast; 11) the northern coastal sector of the mt. conero promontory; 12) the rocky coasts of the gulf of trieste (from mastronuzzi et al., 2017). chelli a. et al. 19 greater vocation, compared to the current one, towards the solution of the problems of applied geomorphology, such as the analysis of the geomorphological hazards and risks and the exploitation of the geomorphological heritage, and 3) to think to symbols that can be more suitable, than the current one, for the creation of a cartographic system that is even more manageable through the use of gis tools. 2. the new geomorphologic legend of italian coast in the framework of the activities for the new geomorphological legend of the italian coast, the wgcm, other than the guide to geomorphological mapping of italy at the scale 1:50,000 (brancaccio et al., 1994), considered besides the results of the other important study concerning geomorphological mapping of the coasts of italy, i.e.: the atlas of italian beaches (atlante delle spiagge italiane; aa.vv., 1997) based on the results of the “conservazione del suolo”, “dinamica dei litorali” sub-project. the legend here proposed collects recent research advancements carried out by the community of italian coastal geomorphologists as well as the results of an articulated scientific discussion developed within the wgcm based on the work that the researches performed by means of 12 case studies (fig. 1) in which a correlation between landforms, wave-climate data, and dynamics is presented. the aim has been to summarise the most recent results in mapping the coastal landforms within the context of a long cultural process, involving the italian scientific community. the realization of the geomorphological legend was, indeed, the result of a theoretical approach, based also on the critical analysis of the classifications proposed during the last century (see finkl, 2004 and references therein), and of a coastal landscape analysis, recognising the landform genesis at a regional scale, while considering their evolution and present dynamics (shepard, 1973) in relation to the sea-level history and evolutionary trends of shore/coast line (valentin, 1952). the study focuses, indeed, on the entire coastal perimeter of italy, including different geodynamic areas, ranging from those characterised by high uplift rates to those stable or subsiding, in the mediterranean climate region, considered as a single morphoclimatic zone. the latter aspect considers the sea energy as “homogenous”, being only affected by lithology and exposure/fetch of each area. the role of 1) inherited landforms (i.e. hillslope or karst cave in submerged areas), 2) volcanic processes, which can characterise a coastal area, 3) continental processes in coastal areas (i.e.: landslides triggered by non-marine processes) and, 4) anthropogenic factors has been also considered. in order to address these issues, the primary task of this study has been to create a classification of coastal landforms which, compared to any previous descriptive/ genetic approaches, will be quantitative and dynamic in relation to processes. the coastal landforms are mainly classified in function of the genetic mechanism still active in their dynamics, while also taking into consideration inheritance, spatial and temporal scales, as well as potential changes in the architecture of the coastal landscape (mastronuzzi et al., 2017). the proposed legend has been subdivided into different thematic layers and at different map scales, reporting morphogenetic, morphometric, and morphodynamic data, and thereby facilitating their input into a geographical information system (gis). in this way, data reported on geomorphological map can be used for several purposes by different stakeholders, from researchers to land-use planners. with the adopted approach, the required geomorphological analysis of coastal landscapes has to be integrated using qualitative and quantitative data on landform genesis and dynamics. at first, it appeared fig. 2 theoretical flow-chart explaining the construction of the new geomorphological legend of the italian coast. the legend has been built starting from the analysis of the coastal landscape recognising the landform genesis, while considering their evolution and present dynamics in relation to the sea-level history and evolutionary trends of shore/coast-line (from mastronuzzi et al., 2017). geomorphologic mappping of coastal areas 20 chelli a. et al. b a fig. 3a,b the new geomorphological legend of the italian coast (from mastronuzzi et al., 2017). useful and necessary to maintain a purely descriptive approach of the coastal landforms and landscapes. however, from the perspective of the actual “end users”, it then became clearly evident that it would be much more useful to provide genetic and dynamic data. for this reason, in the legend, the description and the genesis of inherited landforms along with the description of their current dynamism have been included. information about inheritance and dynamism is especially useful in scenarios where a landform may not correlate to modern dynamic environment. landforms occurring in rocky coastal environment, such as sea caves and karst caves, both emerged and submerged, can be found in the same place even if their genesis results from two different morphogenetic systems and processes. for example, a marine cave could be the evolution of a karstic cave shaped in fully continental condition subsequently modified by marine erosive/ depositional or biochemical processes as the sea-level reached it. references aa vv. (1997) atlante delle spiagge italiane: dinamismo, tendenza evolutiva, opere umane. c.n.r. m.u.r.s.t., selca , 108 tavv. brancaccio l., castiglioni g.b., chiarini e., cortemiglia g.c., d’orefice m., dramis f., graciotti r., la posta e., lupia palmieri e., onorati g., panizza m., pannuzi l., papasodaro f., pellegrini g.b. (1994) carta geomorfologica d’italia 1:50.000. guida al rilevamento. quad. serv. geol. naz., ser.3, 4, pp. 42. castiglioni g.b. (1964) osservazioni morfologiche nella conca di bressanone. mem. accad. patav. ss.ll.aa., 76, 88 pp. finkl c.w. (2004) coastal classification: systematic approaches to consider in the development of a comprehensive scheme. journal of coastal research, 20, 1, 166-213. gruppo di ricerca geomorfologia (grg) (1982) geomorfologia del territorio di febbio tra il m. cusna e il f. secchia (appennino emiliano). geogr. fis. din. quat., 5, 2, 285-360. gruppo di studio delle università emiliane per la geomorfologia (gsueg (1978) geomorfologia dell’area circostante la pietra di bismantova (appennino reggiano). boll. serv. geol. d’italia, xcvii (1976), 107-214. gruppo nazionale di geografia fisica e geomorfologia (gngfg) (1986) ricerche geomorfologiche nell’alta val di peio (gruppo del cevedale). geogr. fis. din. quat., 9, 2, 137-191. gruppo nazionale di geografia fisica e geomorfologia (gngfg) (1987) cartografia della pericolosità connessa ai fenomeni di instabilità dei versanti. boll. soc. geol. ital., 106, 199-221. gruppo nazionale di geografia fisica e geomorfologia (gngfg) (1993) proposta di legenda geomorfologica ad indirizzo applicativo. geogr. fis. dinam. quat., 16, 2, 129-152. gruppo nazionale di geografia fisica e geomorfologia (gngfg) (1995) carta geomorfologica del bacino del trionto. selca, firenze. mastronuzzi g., aringoli d., aucelli p.p.c., baldassarre m.a. bellotti p., bini m., biolchi s., bontempi s., brandolini p., chelli a., davoli l., deiana g., de muro s., devoto s., di paola g., donadio c., fago p., ferrari m., furlani s., ibba a., lupia palmieri e., marsico a., melis r.t., milella m., mucerino l., nesci o., orrú p.e., panizza v., pennetta m., piacentini d., piscitelli a., pusceddu n., raffi r., rosskopf c. m., sansó p., stanislao c., tarragoni c., valente a. (2017) geomorphological map of the italian coast: from a descriptive to a morphodynamic approach. geogr. fis e dinam. quat., 40(2), 161-196. panizza m. (1966) carta e osservazioni geomorfologiche del territorio di calopezzati (calabria). riv. geogr. ital., 73, 1, 40 pp. shepard f.p. (1973) submarine geology. harper and row, new york, 519 pp. valentin h. (1952) die küsten der erde. petermanns geographisches mitteilungen ergänzsungheft, 246. pp. 118. 21 geomorphologic mappping of coastal areas ms. received: may 15, 2018 final text received: may 21, 2018 22 amq abs paoli tepro 231-234.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 231 234 the february 1st, 2014 panicaglia landslide at borgo san lorenzo (mugello) luigi paoli freelancer geologist, via aldo moro 3 borgo san lorenzo, firenze, italy corresponding author: l. paoli <luigipaoli@aruba.it> abstract: on february 1st, 2014 a massive landslide occurred in the area of panicaglia, borgo san lorenzo (mugello, tuscany), involving roads and related subservices, residential and other private buildings that collapsed or were seriously damaged and evacuated. the phenomenon affected the western edge of the fluvial terrace surface and the underlying slope, cut in lacustrine, fluvio-lacustrine and alluvial deposits, on the hydrographical left side of le cale creek (left tributary of the sieve river). geometric, lithostratigraphic, geotechnical and geophysical features of the landslide were analyzed through a survey campaign carried out for the municipality of borgo san lorenzo. keywords: landslides, fluvial terrace, fluvio-lacustrine deposits, plio-quaternary mugello basin, northern apennines, flat dilatometer test dmt 1. introduction on february 1st, 2014 a landslide affected the entire western side of the village of panicaglia (borgo san lorenzo, florence). the landslide involved roads and related subservices, residential and other private buildings that collapsed or were serioulsly damaged and evacuated. the landslide occurred after an important meteoric event that led to conditions of substantial soil saturation. here we report the main results of the geological investigations carried out for the municipality of borgo san lorenzo, that aimed at the reconstruction of the landslide geometry and at establishing geotechnical soil properties for remedial measures planning and designing. 2. geological setting the investigated area lies in the central part of the plio-quaternary, fluvio-lacustrine mugello basin (martini & sagri, 1994), on the western edge of the surface of a fluvial terrace (“terrazzo rissiano” sanesi, 1965), cut by le cale creek and two left tributaries of the same stream, between about 285 m a.s.l. and about 235 m a.s.l. on the terrace surface, alluvial deposits mainly gravel with sandy-silty matrix, ca. 12 m thick, crop out. alluvial deposits are attributable to sieve river synthem, scarperia subsynthem, latest early pleistocene (?)-middle pleistocene (after abbazzi et al., 1995; bortolotti et al., 2010). the depositional environment of these sediments is of the braided-river type. these deposits overlie, by unconformable erosional contact, fluvio-lacustrine deposits of the mugello basin synthem, pulicciano subsynthem, lower pleistocene. fluviolacustrine deposits (see benvenuti, 1997; benvenuti, 2003) mainly consist of gravels with silty-sandy matrix in the upper layers, here up to 9 m thick, that pass down to silty-clayey textures, with sandy-silty intercalations, overconsolidated and fissured. fluvio-lacustrine sediments relate to fan, fan-delta, delta front and lake depositions (benvenuti, 2003). the thickness of fluvio-lacustrine deposits was estimated here to be about 400 m (gemina, 1962). halfway up the slope there is another terrace consisting of alluvial deposits, gravels with sandy -silty matrix, silty sands and clayey silts, ca. 8 m thick, referable to sieve river synthem, luco di mugello subsynthem, middle-upper pleistocene (“terrazzo wurmiano” sanesi, 1965). on the valley floor, near le cale creek, there is a further terrace consisting of mainly gravelly alluvial deposits, ca. 5 m thick, referable to the sieve river synthem, sagginale subsynthem, upper pleistocene(?)-holocene (“terrazzo olocenico” sanesi, 1965). on the scarp and the underlying slope, eluvial-colluvial deposits and anthropic deposits up to about 10 m thick occur. 3. materials and methods the survey campaign consisted in the execution of: i) a conventional topographic survey, with a detailed field mapping of the landslide geomorphological features, ii) cores for a total length of 200 m, iii) 32 standard penetration tests (spt), iv) 3 flat dilatometer tests (dmt), v) 4 electrical cone penetrometer tests (ecpt), vi), geotechnical laboratory tests on 20 collected soil samples, vii) 6 refraction seismic prospecting for a total length of 728.5 m, viii) 1 down hole (50 m), ix) 1 ambient noise horizontalto-vertical spectral ratio (hvsr) measurement. a total of 6 inclinometer casings and 8 open piezohttps://doi.org/10.26382/aiqua.2018.aiquaconference meters have been installed and monitoring during the last four years. 4. results 4.1 morphology of the panicaglia landslide the landslide crown (according to varnes, 1978) develops over a total length of about 320 m and involves the morphologic scarp that delimits the upper terrace surface, from the top, towards the north, down to its base, and then affects the underlying slope. the landslide body extends downhill involving the morphologic scarp that constitutes the upper boundary of the alluvial floodplain of the le cale creek. the length of the landslide body, from the crown to the toe, is about 150 m. the zone involved in the landslide covers an area of about 42.000 m², with an approximate volume of 250.000 m3. the main scarp has a break at a distance of about 180 m from the crown. about 30 m further downhill, there is another scarp that continues up to the ditch that delimits the landslide area to the south. the height of the main scarp, which has progressively increased in the development of the phenomenon, has reached a maximum of about 3.5 m in the north portion of failure, where the primary plastic deformations of the head and of the landslide body occur. proceeding southwards, the height of the main scarp lowers to about 1 m. another characteristic element of the landslide is a fracture antithetical to the crown, which develops parallel to it, at a distance of about 15÷20 m. the landslide foot is not clearly identifiable. the landslide toe, consisting of a swelling to a maximum height of about 1 m, only delineated in the initial phases of the phenomenon, affects the slope that delimits upstream the floodplain of the le cale creek. the landslide is of a complex type, ascribable to rotational slide (in the upper part, with subvertical breaking surface) and to translational slide (in the lower part, with a subparallel sliding surface to the slope). some surficial features, like ondulations, counterslopes and steps, can be referred to previous gravitational activity, index of an active slope dynamics. these quiescent features were reactivated during the 2014 event. the memory of landslides that have affected buildings and pre-existing artefacts in the previous decades points to conditions of generalized instability of the morphological scarp and the underlying areas. 4.2 depth of the sliding surface the sliding surfaces stand at about 16÷18 m from the ground surface in the upper part of the slope, close to the morphological scarp, at about 10÷12 m in the 232 fig. 1 panicaglia landslide geologic map. paoli l. 233 middle section, and at about 4 m in the lower part. the failure surfaces show a subvertical trend in the upper part of the slope, conditioned by the release of overburden pressure determined by the presence of the morphological scarp and by the joints system that involved the gravelly-sandy deposits of the upper terrace, and then assume a subparallel trend to ground surface in the mid-slope and in the foot slope. the slip surfaces, set near the contact between the coarse textured fluvial and fluvio-lacustrine units and the underlying fine textured lacustrine deposits, were already identified during the execution of field geognostic surveys and subse the panicaglia landslide fig. 2 panicaglia landslide geomorphological map (topographic base map is regione toscana technical map – ctr, enhanced with conventional topographical survey). fig. 3 a) dmt-kd method for detecting slip surface in oc clay slopes from totani et al., 1997 b) detecting failure surfaces by dmt in the panicaglia site. quently verified by slope inclinometer data. the results of the investigations allowed us to test, in particular, the reliability of the dmt (marchetti, 1980; astm, 1986) to diagnose, quickly and at relatively low cost, the presence of active or previous sliding surfaces in overconsolidated clay slopes (see totani et al., 1997; marchetti, 1999). 5. discussion and conclusion the lithologic and stratigraphic discontinuity between coarse textured fluvial and fluvio-lacustrine deposits and the underlying fine-textured lacustrine deposits constitutes the weak element of all the slope system. a clear contrast between geotechnical granular behaviour of the upper unit and the cohesive behaviour of the lower unit is evident here. the complex gravitational phenomenon tends to reactivate periodically with the rising of the ground-water table, when conditions of saturation occur close to the ground surface below the morphologic scarp. a sudden increase in porewater pressure along the slip surfaces causes a decrease of soil residual shear strength thus triggering a new failure. landslide shows a state of substantial dormancy once the masses have been rebalanced and the piezometric levels lowered. such an evolution of the phenomenon, with phases of paroxysmal activity triggered by critical meteorological conditions, alternating with periods of dormancy, was also observed for other gravitational movements occurring in similar geomorphological and lithostratigraphic contexts that are very common in mugello. acknowledgements i wish to thank the municipality of borgo san lorenzo for the authorization to data publishing. references abbazzi l., benvenuti m., rook l., masini f. (1995) biochronology of the mugello intermontane basin (northern apennines, italy). il quaternario, 8(1), 510. astm subcommittee d 12.02.10 (1986) schmertmann j.h., chairman suggested method for performing the flat dilatometer test, astm geotechnical testing journal, 9 (2), 93-101 june. benvenuti m. (1997) physical stratigraphy of the fluviolacustrine mugello basin (plio-pleistocene, northern apennines, italy). giornale di geologia, ser. 3°, 59 (1-2), 91-111. benvenuti m. (2003) facies analysis and tectonic significance of lacustrine fan-deltaic successions in the pliocene-pleistocene mugello basin, central italy. sedimentary geology, 157, 197-234. bortolotti v., poccianti c., principi g., sani f. (edited by) (2010) note illustrative della carta geologica d’italia alla scala 1: 50.000 foglio 264 borgo san lorenzo. ispra istituto superiore per la protezione e la ricerca ambientale servizio geologico d’italia, la nuova lito, firenze, pp. 104. gemina (1962) il bacino del mugello. in: ligniti e torbe dell’italia continentale. roma, 61-70. marchetti s. (1980) in situ tests by flat dilatometer. j. geotech. engng div., asce, 106(3), 299-321. marchetti s. (1999) the flat dilatometer (dmt) and its applications to geotechnical design. japanese geotechnical society, tokyo, pp. 90. martini p.i., sagri m. (1994) the late miocenepleistocene extensional basins of the northern apennines: facies distribution and fill architecture. memorie società geologica italiana, 48, 375-380. sanesi g. (1965) geologia e morfologia dell’antico bacino lacustre del mugello firenze. bollettino società geologica italiana., 84 (3), 169-252. totani g., calabrese m., marchetti s., monaco p. (1997) use in-situ flat dilatometer (dmt) for ground characterization in the stability analysis of slope. xv icsmfe, hambourg, september 1997, 1, 607-610. varnes d.j. (1978) slope movement. types and processes. in schuster r.l., krizek r.j. landslides. analysis and control. spec. rep. 176, nat. acad. of sciences, washington d.c. 234 paoli l. ms. received: may 17, 2018 final text received: may 22, 2018 amq abs furlanetto et al palcom 131-134.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 131 134 alnus viridis a sensitive snowfall indicator for past oceanic timberlines in the alps giulia furlanetto 1,2, cesare ravazzi 2, michele brunetti 3, lorena garozzo 2 1 bicocca, dept. of environmental and earth sciences, university of milano, milano, italy 2 idpa cnr, res. group on vegetation, climate and human stratigraphy, laboratory of palynology and palaeoecology, milano, italy 3 isac cnr, bologna, italy corresponding author: g. furlanetto <g.furlanetto1@campus.unimib.it> abstract: we analyse the modern ecological response of mountain alder (alnus viridis) pollen proportions (%) to climatic parameters along altitudinal gradients in two contrasting climate regions of the european alps and calculate pollen accumulation rates (par) to detect the effect of snowmelt runoff. we also compare independent sediment proxies for alluvial events in a high-altitude site of the outer italian alps (armentarga peat bog, 2345 m a.s.l.), which was selected to investigate alnus viridis response in the last 11000 years. keywords: european alps, holocene, alnus viridis, pollen accumulation rate, ehof models, palaeoclimate 1. introduction reconstructing the climate history of the high altitude alps in the present interglacial relies on a large number of natural archives and proxies. the sedimentary record of glacier activity, the most sensitive proxy of climate change, is well stocked but highly discontinuous, thereby making it difficult to decouple temperature and snowfall contributions triggering glacial advances. hopefully, plant and sediment deposition in high altitude areas, either from speleothems, lakes or peat bogs, provides continuous isotopic and biological records. however, in speleothem isotopic records (fohlmeister et al., 2012) a precipitation signal is difficult to discriminate, while most high altitude biological proxies respond primarily to summer temperature modulations (e.g. chironomids and cembran pine (pinus cembra) timberlines). up to present, available validated precipitation records derive from dendroclimatic series only (büntgen et al., 2011). here we propose to analyse the timberline record of alnus viridis (mountain alder) in the oceanic climate regions of the alps to reconstruct holocene oscillations in precipitation, mostly referred to snowfall. mountain alder is a deciduous shrub needing continuous water supply during the growing season, enhanced either by climatic high annual snowfall rate or by edaphic wetness (richard, 1968,1969; mauri & caudullo, 2016). extensive mountain alder shrublands develop in the subalpine altitudinal belt under oceanic, cool temperate climates that hinder cembran pine fitness. edaphic geodiversity allows mountain alder to compete with dwarf pine (pinus mugo), the latter also tolerating oceanic climates, but escaping edaphic wetness. apart from snowfall, timberline forests formed by these alpine dwarf shrubs are controlled by historical biogeography (range dynamics of refugial populations since the last glaciation) and human impact (human fire set to clear forests for pastoralism and mining). given these ecological constraints, we analyse the modern ecological response of mountain alder pollen proportions (%) to climatic parameters along altitudinal gradients in two contrasting climate regions of the alps, and we calculate pollen accumulation rates (par) to detect absolute pollen changes, which may reflect either population fluctuations or snowmelt runoff. we also compare independent sediment proxies for alluvial events in a high-altitude site of the outer italian alps (armentarga peat bog, 2345 m a.s.l., fig. 1), which was selected to investigate alnus viridis response in the last 11,000 years. fig. 1 map of july climatogy (1961-1990) with 170 empd sites (white dots), la thuile valley training set (black dots), upper brembana valley training set (blue dots) and armentarga fossil site (a) plotted. on the right map of annual precipitation (1961-1990) and the location of the two altitudinal training sets. https://doi.org/10.26382/aiqua.2018.aiquaconference 2. material and methods a modern pollen-climate calibration dataset for alnus viridis was created selecting one hundred and seventy alpine sites from the empd-european modern pollen database (davis et al., 2013) in which alnus viridis was kept distinguished and adding fifty-three plots from the two new altitudinal training sets, respectively in an oceanic, outer district of the chain in the central alps (upper brembana valley training set; furlanetto et al., unpublished data) and in a continental inner valley of the western alps (la thuile training set; badino et al., 2018; furlanetto et al., unpublished data) (fig. 1). sitespecific temperature and precipitation series, covering the 1951-2010 period, were reconstructed for each sampling site, by means of the anomaly method as described in brunetti et al. (2012). from these monthly series, mean temperature of the warmest month (tjuly) and the total annual precipitation (pann) were calculated. alnus viridis individual response (fig. 2) was obtained using the extended huisman-olff-fresco fitting method using r 3.2.3 version and ehof package (jansen & oksanen, 2017). sixty-two fossil samples from a lake peat bog record in an outer oceanic district of central alps (armentarga record, fig. 1) were processed following standard methods at the laboratory of palynology and palaeoecology of cnr-idpa in milano, and identified at the optical microscope, reaching a minimum pollen sum of six hundred pollen grains x sample. eight 14c dates were obtained on upland plants remains samples from the study deposits. radiocarbon ages were calibrated and deposition rates were modelled (fig. 3). the calculation of par values for a specific taxon in a sample is not dependent on other taxa occurring in the same sample (birks & birks, 1980). alnus viridis, one of the main timberline ecotone shrub species in the outer oceanic districts of central alps, shows a specific altitudinal par arrangement under modern climate conditions (tab. 1). these par measurements have been used as a modern reference to estimate past plant population densities. pollen-climate transfer functions were derived from weighted averaging partial least squares (wa-pls) regressions (ter braak & juggings, 1993) using a calibration set of two hundred thirty-three modern pollen samples; a 2-component wa-pls model was selected. 132 fig. 2 diagrams showing the simplest statistically significant response model for alnus viridis from the 233 sites and the two single training sets (la thuile valley and upper brembana valley) in relation to a) annual precipitation and b) july temperature as assessed by a hierarchical set of taxon response models within the framework of generalized linear modelling. furlanetto g. et al. 133 3. results in the calibration dataset of two hundred thirty-three modern pollen samples ehof fitting shows that alnus viridis has a significant relationship with annual precipitation being monotonic (optima of ca. 1800 mm at the gradient extreme) and with july temperature being skewed bimodal, with the main optima at ca. 12 °c (fig. 2a, d). in the la thuile valley training set alnus viridis has an estimated optimum of 10 °c and 1050 mm (fig. 2b, e), while in the upper brembana valley training set it has a double optimum with higher temperature and precipitation (respectively 11.5 and 15 °c, 1810 and 1870 mm) (fig. 2c, f). alnus viridis, the main timberline ecotone shrub species in the upper brembana valley, shows a specific altitudinal par arrangement under modern climate conditions (tab. 1). the highest par values in the upper brembana valley training set are observed in the plots l2 and l5 located at mountain altitude (respectively at 1420 and 1940 m a.s.l.) in river corridors and waterfalls with mountain alder scrub with par values of 2400 and 3100 pollen grains cm-2 yr-1 (tab. 1, tl2 and tl5). in the pollen traps at subalpine altitude (tab. 1, tl15, tl14; respectively 2100 and 2180 m a.s.l.), located at the border of mountain alder scrub with continuous understory of ericaceae, par values are about 700 pollen grains cm-2 yr-1. modern par data from armentarga peat bog show values that range from 100 to 400 pollen grains cm-2 yr-1 (tab. 1, tl10 and tl10 lt). these par measurements have been used as a modern reference to estimate past plant population densities (fig. 3). palaeoecological data from the armentarga peat bog (fig. 3) show a general increase of alnus viridis from ca. 7,000 years cal bp (alnus viridis % and par) and a concurrent increase of lithic fragments concentration and of silicoclastic + oxides contents with an opposed decrease of pinus sylvestris/mugo and pinus cembra type. starting from 1,300 years cal bp a sharp decrease of alnus viridis par values and increase of total p occur till 300 years cal bp. pollen-inferred annual precipitation show a sharp increase from 7,200 years cal bp with short phases of precipitation decrease during the early bronze age and roman period (fig. 3). 4. discussion and conclusion the observed alnus viridis response offset between the paired sites considered is related to variations in local climates (from oceanic external chains to continental inner districts). alnus viridis vegetation needs continuous water supply during the growing season, enhanced by high annual snowfall rate and good soil water balance. accordingly, in alpine oceanic climates, the ecological response of the species expands downstream especially along avalanche corridors but also on northern slopes, due to a general increase in soil moisture. this results in a displacement of its optima towards higher temperature and precipitation (fig. 2c, f, upper brembana valley training set), thus reducing the overall tjuly signal of alder pollen abundance in oceanic climates (fig. 2f). palaeoecological and sedimentary data from armentarga peat bog show an increase of snowmelt runoff from ca. 7,000 to 5,000 years cal bp (alnus viridis par values relative to respective %, lithic fragments concentration and silicoclastic + oxides contents) and decrease of temperature. this humid phase is confirmed by a sharp increase in pollen-inferred annual precipitation since 7200 years cal bp (fig. 3). alnus viridis par values show significant peaks from 6,000 to 1,300 years cal bp, comparable or above the modern absolute par values obtained in the mountain alder scrub (pollen traps tl 15 and tl14), thus arguing for phases of alder timberline rises. starting from 1300 years cal bp, the record of alnus viridis par values is negatively correlated to an increase of total phosphorus, suggesting that the long since wellestablished alder subalpine belt was affected by high human impact since the early middle ages. acknowledgements this extended abstract is a result of a phd research project sponsored by the milano-bicocca university, dept. of earth and environmental sciences, with the co-tutoring and support of the cnr-idpa. we are grateful to parco delle orobie bergamasche for the support to this research program. references badino f., ravazzi c., vallè f., pini r., aceti e., brunetti m., champvillair e., maggi v., maspero f., perego r., orombelli g. (2018) 8800 years of high-altitude vegetation and climate history at the rutor glacier forefield, italian alps. evidence of middle holocene timberline rise and glacier contraction. quaternary science reviews, 185, 41-68. alnus viridis a sensitive indicator for oceanic climate tab. 1 modern alnus viridis par values based on pollen monitoring data in the upper brembana valley, representing the period 2016-2017. the location of the upper brembana valley training set is shown in fig. 1. birks h.j.b., birks h.h. (1980) quaternary palaeoecology. arnold e, london, uk. brunetti m., lentini g., maugeri m., nanni t., simolo c., spinoni j. (2012) projecting north eastern italy temperature and precipitation secular records onto a high-resolution grid. physics and chemistry of the earth, 40-41, 9-22. büntgen u., tegel w., nicolussi k., mccormick m., frank d., trouet v., kaplan j.o, herzig f., heussner k.u, wanner h., luterbacher j., esper j. (2011) 2500 years of european climate variability and human susceptibility. science, 331, 578582. davis b.a.s., zanon m., collins m., mauri a., bakker j., barboni d., barthelmes a., beaudouin c., birks h.j.b., bjune a.e. et al. (2013) the european modern pollen database (empd) project. vegetation history and archaeobotany, 22(6), 521-530. fohlmeister j., vollweiler n., spötl c., mangini a. (2012) comnispa ii: update of a mid-european isotope climate record, 11 ka to present. the holocene, 23 (5), 749-754. jansen f., oksanen j. (2017) extended hof (huisman-olff-fresco) models. r package version 1,8. mauri a., caudullo g. (2016) alnus viridis in europe: distribution, habitat, usage and threats. in: sanmiguel-ayanz j., de rigo d., caudullo g., houston durrant t., mauri a. (eds) european atlas of forest tree species. publication office of the european union, luxembourg, p. 68. richard l. (1968) écologie de l'aune vert (alnus viridis): facteurs climatiques et édaphiques. documents pour la carte de végétation des alpes, 6, 107-158. richard l. (1969) une interprétation éco-physiologique de la répartition de l'aune vert (alnus viridis). documents pour la carte de végétation des alpes, 7, 7-23. ter braak c.j.f., juggings s. (1993) weighted averaging partial least squares regression (wapls): an improved method for reconstructing e n v i r o n m e n t a l v a r i a b l e s f r o m s p e c i e s assemblages. hydrobiologia, 269/270, 485-502. 134 furlanetto g. et al. fig. 3 fossil alnus viridis par data and pollen inferred annual precipitation from armentarga fossil record compared with other palaeoecological and geochemical data. ms. received: may 4, 2018 final text received: may 17, 2018 available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 55 58 natural and anthropic events at la polledrara di cecanibbio (italy, rome): some significant examples cerilli eugenio 1 , fiore ivana 2 1 soprintendenza speciale archeologia belle arti e paesaggio di roma, roma, italy (collaborator) 2 museo delle civiltà. collaboratrice servizio bioarcheologia, roma, italy corresponding author: e. cerilli <cerillieugenio@gmail.com> abstract: in the site of la polledrara di cecanibbio (mis 9) the analysis of the river-bed morphology, combined to that of the spatial disposition of the accumulated skeletal remains and of their taphonomic modifications, allows to reconstruct the events that have led to the formation and evolution of the deposit. keywords: middle pleistocene, river-bed, elephant-human interactions 1. introduction the site of la polledrara di cecanibbio is located in the sabatini volcanic district, at an altitude of 83 m a.s.l., about 22 kilometers from rome near the via di boccea. between 1985 and 2013 the site was subject to regular excavations, funded by the then soprintendenza speciale per i beni archeologici di roma today soprintendenza speciale archeologia belle arti e paesaggio di roma (ssabap-rome), which exposed on an area of about 1200 meters square a bed portion of a small water course cut into a bank of compact volcaniclastic deposits (anzidei et al., 2012; castorina et al. 2015; santucci et al., 2016). in the year 2000, with a financial support of mibact, about 900 square meters of the site were covered by a prefabricated structure and it became a museum open to the visitors (fig. 1). the site is characterized by fluvial deposits that pass to fluvio-palustrine during a phase of high stand of the sea level (anzidei et al., 2012). the mineralogical composition of the volcanoclastic sediments that have filled the river-bed indicates an origin from several source rocks of the sabatini volcanic district (castorina et al., 2015). the recent dating of 325±2 ka, obtained with the 40 ar/ 39 ar method (pereira et al., 2017), confirm that the la polledrara site developed at the beginning of mis 9, in the final phase of the transgressive systems tract of the ponte galeria 6 fourth order sequence (anzidei et al., 2012), and therefore to the aurelia formation (milli & palombo, 2005; milli et al., 2011). among the 20,000 skeletal remains found, palaeoloxodon antiquus and bos primigenius are the dominant species followed by cervus elaphus; less abundant are the remains of sus scrofa, stephanorhinus cf. hemitoechus, equus ferus, canis lupus, vulpes vulpes, meles meles, felis silvestris, macaca sylvanus, lepus sp., murids and arvicolids; the herpetofauna and the avifauna (under study) are also well represented. on the basis of the present species, the isotopic data and the microwear on some elephant molars, it was hypothesized that at the time of deposition of the fossiliferous layers the landscape of la polledrara was characterized by a dense arboreal cover interspersed with open spaces in conditions of moderately humid and temperate/warm-temperate climate (palombo et al., 2005). the lack of pollen and plant fossil remains does not enable to confirm this hypothesis. the anthropic presence (homo heidelbergensis) is testified by hundreds of artifacts on flint and numerous tools on elephant bone. the site had to represent a point of attraction, as a source of food and raw material, for the hunter-gatherers bands who frequented the territory, as is clearly indicated for example by a skeleton of p. antiquus in partially preserved anatomical connection, the taphonomic layout of some of its bones and the archaeological artifacts associated with (santucci et al., 2016). 2. bed morphology and taphonomy of bone remains the action of the water flow, that took place in particular in the first phase of the river's history, is particularly evident on the surface of the river-bed where two areas are separated by a step of about 80 cm in height, which reduce until disappear towards the center of the watercourse. above it, the river bottom appears very irregular, characterized by raised and depressed areas. these irregularities obviously influenced the directions and intensities of the water flows. in this area the faunal remains have been almost all accumulated in the depressed areas, while they are scarce in the elevated portions, more exposed to the hydraulic action. furthermore, the summit of many of these zones have flat shape and show evident mud-cracks, testifying to their sub-aerial exposure. these evidences would indicate that periodic oscillations of the water table have occurred in this stretch of the channel, perhaps even noticeable and probably linked to seasonal variations in rainfall. otherwise, downstream of the step, the river bottom is flat, and the faunal remains are distributed along the https://doi.org/10.26382/aiqua.2018.aiquaconference surface of the river-bed with a distribution that reflects the current flow characteristics. for example, in some areas the long and narrow skeletal elements, such as the elephant's tusks, were arranged parallel or transversely to the water flow direction and constituted a barrier that favored the accumulation of other elements. in some cases, the whirlpools linked to the acceleration phase of the flow around an obstacle produced an undererosion around the skeletal element. except for a few exceptions, the faunal remains deposited on the bottom and often also the lithic ones, show extensively striated surfaces, high degree of fluitation of the upper face exposed to the water flow. on the other hand, the lower face of the remains, resting on the 56 cerilli e., fiore i. fig. 1 overview on the museum's showcase of the site, seen by se (ssabap-rome archive). fig. 2 right metacarpus of bos primigenius deposited with the plantar side at the bottom of the bed. the dorsal side (a), the margins of the proximal epiphysis (b) and the surface of the distal condyles (c) are strongly fluitated and abraded, with randomly oriented sediment abrasion scratches (d, e). the plantar side (f, g, h) is poorly fluitated, but intensively eroded, probably due to chemical aggression of the underlying sediment, the erosion has almost completely erased the traces of abrasion which are visible only in some areas (i). on the dorsal side and, less frequently, on the plantar one traces of plant roots are visible. the low degree of alteration from the exposure to atmospheric agents (behrensmeyer, 1978), especially wet-dry cycles, indicates that this skeletal element has been covered with sediment in a fairly short time (archive ssabap-rome). 57 bottom of the bed, is not transported instead it is very often strongly eroded (fig. 2). furthermore, on the remains deposited on the bottom, impact or trampling fractures are clearly evident, as well as the marks of intentional anthropogenic fracture for bone marrow extraction are well testified. finally, there is a marked differential conservation of the anatomical elements depending on the strength of their bony tissue: the resistant portions of elements of large animals, mainly represented by adult individuals, are more represented on the bottom, while the elements of young or small animals, or the skeletal portions with more abundant spongy tissue or with thinner compact tissue, are rare. on the bottom, elements in anatomical connection are never recognized, while they are well represented in the successive marshy phase, together with skeletal parts of small animals. these taphonomic characteristics indicate that during the fluvial phase the remains were transported by a muddy current and that, once deposited on the bottom, generally they did not significantly shift from their primary position and remained exposed to the water flow for a prolonged period of time. on the other hand, the remains deposited in the subsequent filling and swamping phase of the channel show show no or poor degree of fluitation, but in any case they are always intensively striated, where their surface has been able to record this alteration. this indicates that, after their transport within a muddy flow and their subsequent deposition, they were almost immediately covered by sediment. the formation of large accumulations of sediment caused the death of three elephants trapped in the mud (anzidei et al., 2012). one of these is of particular interest. in an area near the right bank, the skeleton of a pachyderm, certainly dead because trapped in the mud, is in close spatial relationship with more than 600 stone artifacts that indicate the scavenging of the carcass (santucci et al., 2016). anthropic exploitation (fig. 3) is also documented by remains with traces of impact and cutting from lithic tools, by percussion chips and bone tools with traces of use. some diaphyses of elephant's taphonomic examples at la polledrara di cecanibbio fig. 3 anthropogenic modifications in bones. 1 (a) femur with percussion flake still connected and (b) detail. 2 bone tools made from an elephant diaphysis. 3 (a) diaphysis of an elephant's long bone with concentration of percussion scars and of overlapped scars (yellow arrows), (b) detail at the microscope of striae from lithic tool. 4 (a-b) conchoidal flakes on a very large mammal long bone diaphysis, resulting from intentional bone fracturing, this kind of flake usually is not due to bone fracturing for marrow extraction, but rather may be the consequence of bone tool manufacturing. long bone show fracture patterns and a quantity, localization, concentration and overlapping of scars to interventions aimed to shape the raw material rather than to butchering activities. in conclusion, it seems undoubted that in la polledrara the main agents of accumulation of the bones were the flow of water inside a river-bed and the mud of the subsequent marsh phase, but it is also undeniable that the river and the marsh have attracted the human groups of hunter-gatherers who frequented the territory, because of the formidable possibilities of exploitation of animal carcasses, both for food and for the recovery of hard animal raw materials to produce artifacts. references anzidei a.p., bulgarelli g.m., catalano p., cerilli e., gallotti r., lemorini c., milli s., palombo m.r., pantano w., santucci e. (2012) ongoing research at the late middle pleistocene site of la polledrara di cecanibbio (central italy), with emphasis on human-elephant relationships. quaternary international, 255, 171-187. beherensmeyer a.k. (1978) taphonomic and ecologic information from bone weathering. paleobiology, 4 (2), 150-162. castorina f, masi u., milli s., anzidei a.p., bulgarelli g.m. (2015) geochemical and sr-nd isotopic characterization of middle pleistocene sediments from the paleontological site of la polledrara di cecanibbio (sabatini volcanic district, central italy). quaternary international, 357, 253-263. milli s., palombo m.r. (2005) the high resolution sequence stratigraphy and the mammal fossil record: a test in the middle-upper pleistocene deposits of the roman basin (latium, italy), quaternary international, 126-128, 251-270. milli s., palombo m.r., anzidei a.p. (2011) i depositi pleistocenici di ponte galeria e la polledrara di cecanibbio, guidebook post-congress field trip, aiqua 2011 (italian association for quaternary studies), rome, 26 february 2011. palombo m.r., filippi m.l., iacumin p., longinelli a., barbieri m., maras a. (2005) coupling tooth microwear and stable isotope analyses for palaeodiet reconstruction: the case study of late middle pleistocene elephas (palaeoloxodon) antiquus teeth from central italy (rome area), quaternary international, 126-128, 153-170. pereira a., nomade s., faulguères c., bahain j.j., tombret o., garcia t., voichet p., bulgarelli g.m., anzidei a.p. (2017) 40 ar/ 39 ar and esr/u-series data for the la polledrara di cecanibbio archaeological site (lazio, italy). journal of archaeological science, reports, 15, 20-29. santucci e., marano f., cerilli e., fiore i., lemorini c., palombo m.r., anzidei a.p., bulgarelli g.m. (2016) palaeoloxodon exploitation in the late middle pleistocene site of polledrara di cecanibbio (rome, italy). quaternary international, 406, 169-182. 58 cerilli e., fiore i. ms. received: may 6, 2018 final text received: may 18, 2018 imp.chiarini& le unità stratigrafiche di riferimento nella rappresentazione cartografica dei depositi plio-quaternari continentali nel progetto carg esempi: arco alpino, pianura padana e sardegna edi chiarini*, maurizio d'orefice & roberto graciotti apat servizio geologico d'italia/dipartimento difesa del suolo, roma, italy *corresponding author: e. chiarini, apat servizio geologico d'italia/dipartimento difesa del suolo, via curtatone, 3, 00185 roma, italy. e-mail: <edi.chiarini@apat.it> abstract: e. chiarini, m. d'orefice & r. graciotti, reference stratigraphic units for mapping plio-quaternary continental deposits in the carg project: examples from alps, po plain, sardinia. plio-quaternary continental deposits have an important role in the new geological map of italy at 1:50.000 scale (carg project). the geological survey of italy suggests mapping such deposits through the unconformity-bounded stratigraphic units (ubsu), after adaptations. in this work, examples from different areas in northern italy and sardinia are analysed and compared. the results are: a) a standard rule for use of the ubsu is not applicable; b) the ubsu provide a tool for regional or interregional syntheses only in a few cases (e.g. in the large sedimentary po basin), while for minor basins (e.g. the alpine valleys) they represent a local meaning; c) consequence problems in hierarchy and correlation of units of neighbouring areas occur also. parole chiave: cartografia geologica, unità a limiti inconformi, depositi plio-quaternari continentali, italia. keywords: geological mapping, unconfomity-bounded stratigraphic units, plio-quaternary continental deposits, italy. il quaternario italian journal of quaternary sciences 21(1a), 2008 51-56 1. premessa nella nuova carta geologica d'italia alla scala 1:50.000, che il servizio geologico sta realizzando con il coinvolgimento delle regioni e delle province autonome e con il supporto scientifico delle università e del cnr (progetto carg), è stata riservata una grande importanza al rilevamento dei depositi continentali plioquaternari, almeno rispetto alle precedenti edizioni, per il crescente interesse da parte della comunità scientifica, ma soprattutto per l'importanza applicativa che rivestono. sono state pertanto definite le linee guida per la rappresentazione cartografica ed è stato affrontato il problema della classificazione stratigrafica di tali depositi (c.n.r., 1992; servizio geologico d'italia; 2001; apat, 2005a; cis, 2003). 2. le unità stratigrafiche di riferimento le unità stratigrafiche che meglio si adattano ai depositi continentali plio-quaternari sono le unità a limiti inconformi (ubsu) e le unità allostratigrafiche, delimitate inferiormente e superiormente da discontinuità stratigrafiche significative. l'uso delle unità litostratigrafiche è invece limitato ai corpi geologici caratterizzati da litologie sufficientemente omogenee. le unità istituite devono essere chiaramente identificabili sul terreno e cartografabili alla scala 1:50.000, quindi avere un certo spessore minimo e un'area di affioramento sufficientemente estesa. dopo un primo periodo in cui sono state adottate anche le unità allostratigrafiche, il servizio geologico ha raccomandato a tutti gli operatori del progetto carg la scelta delle unità a limiti inconformi (servizio geologico d'italia, 2001) per la sostanziale equivalenza dei due tipi di unità nell'utilizzazione pratica all'interno del progetto, perché, a differenza delle unità allostratigrafiche, sono previste nella international stratigraphic guide (salvador, 1994) e perché possono includere qualsiasi altro tipo di unità stratigrafica, sia in successione verticale che laterale, ivi comprese le unità litostratigrafiche. con la più recente guida italiana alla classificazione e alla terminologia stratigrafica (cis, 2003) l'uso delle unità allostratigrafiche nella carta geologica è stato definitivamente abbandonato. le ubsu nel progetto carg molto spesso hanno validità locale e non regionale, come preferibilmente previsto nella definizione. inoltre la valutazione del rango delle unità, in base al grado di discordanza angolare, all'intervallo temporale dello hiatus stratigrafico e all'estensione delle discontinuità-limite, risulta estremamente soggettiva. accanto alle ubsu e alle unità litostratigrafiche, nel progetto carg sono spesso adottate le unità informali, per introdurre differenziazioni stratigrafiche di rango inferiore all'interno di subsintemi o in assenza dei requisiti formali. infine altre unità informali, ma prive di specifiche connotazioni stratigrafiche, sono spesso presenti nella parte alta della legenda dei fogli geologici, per raggruppare i depositi più recenti. 52 e. chiarini et al. 3. esempi relativi all'arco alpino, alla pianura padana e alla sardegna dall'esame dei criteri adottati nei fogli realizzati dalle regioni dell'italia settentrionale e dalla regione sardegna, emergono differenze rilevanti nel significato attribuito alle ubsu anche quando i contesti geologici sono paragonabili. la tab. 1 riassume, nell'esempio di uno o più fogli geologici per ogni regione, il tipo, il numero, il rango, l'età e l'estensione delle unità istituite. sintetizzando una casistica molto ampia, emerge come nei fogli della sardegna sud-occidentale, della liguria, dell'emilia-romagna e in parte del veneto le ubsu siano valide nell'ambito di un bacino sedimentario, mentre in tutti gli altri casi, relativi all'arco alpino, siano state generalmente distinte successioni diverse di unità per ogni bacino idrografico o glaciale principale, o per porzioni diverse dello stesso bacino. le ubsu istituite con il primo approccio, in presenza di elementi di correlazione comprendono anche i depositi delle valli collegate al bacino sedimentario, mentre in tutte le altre situazioni si ricorre ai raggruppamenti privi di formali connotazioni stratigrafiche; il secondo approccio, più analitico, prevede un uso estensivo delle ubsu, ma comporta alcune problematiche, non sempre risolte efficacemente, al passaggio dai settori vallivi a quelli di pianura, dove le unità definite per i diversi bacini idrografici possono essere in continuità. in tutti i fogli della sardegna sud-occidentale i depositi pleistocenici sono classificati mediante una sola successione di unità a limiti inconformi (tab. 1), mentre i depositi olocenici sono distinti soltanto in base alla facies. fra i fogli della liguria finora completati solo nel foglio la spezia sono state applicate le ubsu, individuando superfici di inconformità significative a livello di bacino sedimentario. nel bacino di sarzana (bassa val di magra, tab. 1) sono stati distinti due sintemi separati da una discordanza angolare, suddivisi in subsintemi in base alla presenza di discontinuità di rango inferiore. in valle d'aosta i depositi superficiali, principalmente legati al glacialismo, sono riferiti in massima parte all'ultimo episodio glaciale del pleistocene superiore e al successivo periodo post-glaciale, fino all'attuale (carraro & gianotti, in elaborazione). in assenza di elementi di correlazione certi e non essendoci solitamente continuità fisica tra depositi di bacini diversi erano state inizialmente distinte tre successioni (dora baltea, bacini tributari maggiori e bacini tributari minori), ma nella sintesi finale è stata definita una sola successione di unità stratigrafiche (tab. 1), precisando però che il grado di affidabilità delle correlazioni diminuisce all'aumentare dell'età. in piemonte con il progetto carg è stato rilevato tutto il territorio compreso fra l'alta val di susa e la pianura ad est di torino. nei fogli torino est e torino ovest le unità non distinte in base al bacino di pertinenza comprendono sia le cosiddette unità ubiquitarie, sia i depositi recenti ed attuali dei corsi d'acqua, organizzati in unità a limiti inconformi, in evidenti rapporti di continuità fra loro e quindi non distinguibili in unità diverse, sia, infine, i depositi più antichi, precedenti all'impostazione degli attuali bacini idrografici. i depositi glaciali dell'anfiteatro di rivoli-avigliana (bacino della dora riparia) sono stati distinti in 4 sintemi principali, articolati in vari subsintemi, che rappresentano altrettante espansioni glaciali e abbracciano un intervallo temporale che va dal pleistocene medio alla fine del pleistocene superiore (fioraso et al., in elaborazione). anche nei fogli realizzati nell'ambito delle province autonome di trento e bolzano si individuano successioni specifiche di ubsu per i principali bacini glaciali o idrografici. nel foglio malè i depositi relativi a tutti i cicli sedimentari precedenti l'ultima massima espansione glaciale, di scarsissima estensione e difficilmente cartografabili alla scala 1:50.000, sono raggruppati nel supersintema di monte spinale, mentre i depositi glaciali e fluvioglaciali riferiti al last glacial maximum e alle fasi tardoglaciali sono compresi nel sintema del garda (tab. 1). il sintema post-glaciale alpino include i depositi di età compresa tra la fine dell'ultimo glaciale e l'olocene; è un'unità ubiquitaria diffusa in tutto l'ambito alpino, che ritroviamo anche nei fogli del veneto e che corrisponde al sintema del po dei fogli lombardi e della pianura veneto-friulana. nei fogli della regione lombardia le unità a limiti inconformi, istituite tutte le volte che i corpi geologici presentano superfici limite ben riconoscibili, coincidenti con il limite di un ciclo sedimentario, sono integrate dalle unità litostratigrafiche, utilizzate per corpi geologici distinguibili soltanto in base alle caratteristiche interne (bini & corbari, in elaborazione). sintemi e subsintemi sono legati ad un singolo evento sedimentario generalmente valido a livello di bacino idrografico o glaciale, mentre i supersintemi assumono un significato analogo a quello del gruppo delle unità litostratigrafiche; raggruppano sintemi in successione verticale ma anche laterale, quindi possono essere estesi a più bacini. anche nei fogli del friuli venezia giulia le ubsu sono associate alle unità litostratigrafiche. nel foglio maniago (tab. 1) i depositi più antichi sono raccolti nel supersintema del friuli, delimitato alla base e al tetto da superfici di natura erosiva marcatamente diacrone, che raccoglie vari tipi di unità, distinte in base al bacino di appartenenza, in successione sia verticale sia laterale (avigliano et al., in elaborazione). i depositi dell'lgm, raccolti in sintemi diversi per ogni bacino idrografico, sono in evidenti rapporti di eteropia nel settore meridionale del foglio e dovrebbero, quindi, costituire una sola unità. il bacino di riferimento nei fogli della regione emilia-romagna è il bacino sedimentario padano, nell'ambito del quale sono stati già completati molti fogli, definendo delle ubsu (tab. 1) di estensione regionale ed integrando i dati di superficie con quelli di sottosuolo. in genere, i sintemi, cui corrispondono nel sottosuolo spessori dell'ordine delle centinaia di metri, sono delimitati da discontinuità regionali di origine strutturale, evidenti nei profili sismici. i subsintemi sono invece connessi alla ciclicità climatico-eustatica alla scala dei 100.000 anni. le ubsu riconosciute nei settori intravallivi del margine appenninico sono state estese al sottosuolo della pianura. nei fogli delle aree di laguna e della pianura del veneto il supersintema di venezia, di età compresa fra il pliocene e la fine del pleistocene medio, comprende tutti i depositi che poggiano sulla discontinuità messiniana e che sono limitati al tetto da una discontinuità corrispondente al passaggio da sedimenti di ambiente lagunare-deltizio a sedimenti alluvionali. il successivo supersintema di mestre è limitato superiormente da una superficie di tipo erosivo o di “non depo53le unità stratigrafiche di riferimento nella rappresentazione ... regione rango e nome estensione foglio unità utilizzate delle unità e numero età delle unitàdei subsintemi unità informali olocenesardegna f. 557 cagliari ubsu s. portovesme pleistocene superiore s.s. portoscuso pleistocene superiore parte alta s.s cala mosca tirreniano unità informali olocene non distinte in base al bacino liguria ubsu s. di pian di barca pliocene?-pleistocene inferiore paleovalle pian di barcaf. 248 s. b. val di magra 4 subsintemi pleistocene bacino sedimentario sarzanala spezia s. sarzana 4 subsintemi miocene sup.?-pleistocene inf.? unità informali uid (ubiquitarie in formazione) olocene-attuale unità non distinte in base al valle d'aosta uin (ubiquitarie formate) olocene bacino di appartenenza f. 089 courmayeur ubsu s. miage 2 subsintemi olocene s. ivrea 4 subsintemi pleistocene sup.-olocene inferiore bacino dora baltea ss serra di ivrea (penultimo pleistocene mediopleistocene sup. glaciale ed episodi pre-eemiano) unità informali uid pleistocene medio-attuale uin pleistocene medio-olocene 3 unità informali pliocene medio-pleistocene mediopiemonte f. 155 ubsu s. di regia mandria 2 subsint. pleistocene medio-pleistocene sup. bacino stura di lanzo torino ovest sintema di la mandria sintema di fiano s. di magnoletto 2 subsintemi pleistocene medio-pleistocene sup. bacino dora riparia s. di frassinere 2 subsintemi s. di bennale 2 subsintemi sintema di s. gillio sintema di ponte pietra pleistocene inferiore-olocene bacino sangone sintema del sangone sintema di fornello trento e bolzano ubsu sintema post-glaciale alpino 1ss olocene non distinte in base al bacino f. 042 malè ubsu sintema del garda 2 subsintemi pleistocene superiore bacino adige supersintema di monte spinale pliocene-pleistocene superiore unità gruppi, formazioni pliocene?-pleistocene non distinte in base al bacino litostratigrafiche supersistema di palazzago pliocene sup.-pleistocene sup. di appartenenza ubsu sintema del po pleistocene sup.-olocene unità supersintema di stalletto pleistocene superiore litostratigrafiche supersintema del f. mella pleistocene superiore supersintema di sarezzo pleistocene medio supersintema di inzino pleistocene medio ubsu sintema di regne pleistocene medio supersintema di stravignino pleistocene medio bacino val trompia supersintema t. faidana pleistocene medio supersintema di dosso baione pleist. inferiore?, pleist.medio? lombardia gruppo di lavone pleistocene medio f. 099 iseo conglomerato di lodrino pleistocene medio 1:25.000 conglomerato di mamertino neogene post-messiniano conglomerato di ombriano tardo miocene pre-messiniano ubsu supersintema dei laghi pleist. superiore sintema di cantù pleist. superiore supersintema di monterotondo pleist. medio pleist sup.? sintema di m. piane pleist. medio s. di camignone pleist. medio s. di paderno di franciacorta pleist. medio bacino camuno supersintema colma del piano pleistocene sup.? supersintema di m: valenzano pliocene sup.?, base pleist. medio? unità gruppo di foppe pleistocene medio litostratigrafiche ceppo di cremignane pleistocene medio basale? ceppo di poltragno pliocene sup.?-pleist. inf.? unità informali pleistocene-oloceneemilia romagna fogli 179, 199, ubsu ss emiliano-romagnolo pleistocene medio-olocene 219, 223, 237, s emiliano-romagnolo superiore pleistocene medio-olocene bacino sedimentario padano 240-241, 256 s emiliano romagnolo inferiore pleistocene medio da 1 a 5 subsintemi subsintemi: circa 100.000 ciascuno da 1 a 5 unità informali unità informali uin pleistocene medio-olocene ubsu sintema del po olocene distinzioni in base al bacino friuli venezia unità supersintema del friuli pliocene-pleistocene superiore idr. solo per le sottounità del giulia litostratigrafiche formazioni ss del friuli f. 065 ubsu sintema spilimbergo 4 subsintemi pleistocene superiore bacino del tagliamentomaniago sintema di sequals 2 subsintemi pleistocene superiore bacino del meduna sintema di vivaro pleistocene superiore bacino del cellina veneto ubsu sintema del po 2 subsintemi olocene f. 128 supersintema di mestre pleistocene sup. bacino sedimentario padano venezia supersintema di venezia 1 subsin. pliocene-pleistocene med. tab. 1 classificazione stratigrafica dei depositi pliocenici e quaternari continentali nel progetto carg. ss) supersintema/i; s) sintema/i; ss) subsintema/i. stratigraphic classification of plio-quaternary deposits in the carg project. ss) supersinthem(s); s) sinthem(s); ss) subsinthem(s). sizione” caratterizzata dalla presenza di un paleosuolo argilloso, il caranto, che rappresenta in queste aree un ottimo livello guida e segna il passaggio alle unità oloceniche (tab. 1). 4. conclusioni gli esempi mostrano in primo luogo che nella cartografia dei depositi continentali pliocenici e quaternari le ubsu possono essere realmente utilizzate come strumento di sintesi regionale solo in presenza di bacini sedimentari sufficientemente estesi, come il bacino padano. negli altri casi, in ambito alpino, l'estrema diversificazione dell'evoluzione geologica di alcune aree, la discontinuità dei litosomi e soprattutto l'assenza di elementi utili per effettuare delle correlazioni rende necessaria l'istituzione di successioni specifiche di ubsu per ogni bacino idrografico o glaciale o di unità valide soltanto a scala locale. in questi casi le ubsu hanno finalità più analitiche, assumendo in pratica lo stesso significato delle unità allostratigrafiche. nelle aree degli anfiteatri glaciali il loro impiego può ritenersi soddisfacente mentre nelle pianure alluvionali genera problematiche di non facile risoluzione. in secondo luogo occorre sottolineare come nelle varie regioni dell'italia settentrionale non esista un criterio univoco per l'applicazione delle ubsu. ciò in parte dipende dal diverso contesto geologico, in parte da diverse scelte di fondo degli studiosi del quaternario che operano nei fogli. in molti casi non c'è accordo né sui nomi né sull'ordine gerarchico delle unità sintemiche adottate in fogli realizzati da operatori diversi, anche in presenza di livelli di riferimento, condizione molto fortunata. il problema è emerso in maniera evidente nei fogli della pianura padano-veneta, ove i confini amministrativi delle varie regioni tagliano settori dello stesso bacino sedimentario, ed è stato affrontato in una riunione congiunta del comitato d'area per la pianura padana e di quello per le alpi orientali, centrali ed occidentali, tenutasi a padova nel giugno 2004, senza però trovare una vera soluzione, come emerge dallo schema di correlazione tra le unità stratigrafiche più recenti delle regioni emilia-romagna e veneto presentato in fig. 1. bibliografia apat-servizio geologico d'italia/dipartimento difesa del suolo (2005a) indicazioni per la rappresentazione cartografica del quaternario continentale. circolare carg disponibile sul sito web www.apat.it. apat-servizio geologico d'italia/dipartimento difesa del suolo (2005b) carta geologica d'italia alla scala 1:50.000 e relative note illustrative. fogli 128 “venezia”, 179 “ponte dell'olio”, 199 “parma sud”, 219 “sassuolo”, 248 “la spezia”, 256 “rimini” e 557 “cagliari”. apat-servizio geologico d'italia/dipartimento difesa del suolo (in elaborazione) carta geologica d'italia alla scala 1:50.000. fogli 042 “malè”, 065 “maniago”, 089 “courmayeur”, 099 “iseo”, 155 “torino ovest”. disponibili sul sito web www.apat.it. avigliano r., monegato g. & paiero g. (in elaborazione) successione continentale pliocenica-quaternaria. in dal piaz g., castellarin a., martin s., selli l., carton a., pellegrini g. b., casolari e., daminato f., montresor l., picotti v., prosser g., santuliana e. & cantelli l. note illustrative del f. 042 “malè” della carta geologica d'italia alla scala 1:50.000. apat servizio geologico d'italia/dipartimento difesa del suolo. bini a. & corbari d. (in elaborazione) stratigrafia dei depositi neogenico-quaternari. in cassinis g., corbari d., falletti p. & perotti c. (a cura di) note illustrative del f. 099 “iseo” della carta geologica d'italia alla scala 1:50.000. apat servizio geologico d'italia/dipartimento difesa del suolo. 54 fig. 1 schema di correlazione tra le unità stratigrafiche più recenti delle regioni emiliaromagna e veneto. correlation of the youngest stratigraphic units of the emilia romagna and veneto. e. chiarini et al. carraro f. & gianotti f. (in elaborazione) stratigrafia dei depositi quaternari. in perello p. & gianotti f. (a cura di) note illustrative del f. 089 “courmayeur” della carta geologica d'italia alla scala 1:50.000. apat servizio geologico d'italia/dipartimento difesa del suolo. cis-commissione italiana di stratigrafia (2003) guida italiana alla classificazione e alla terminologia stratigrafica. quaderni, ser. iii, 9, 155 pp., apatdipartimento difesa del suolo. c.n.r.-commissione per la cartografia geologica e geomorfologica (1992) carta geologica d'italia1:50.000. guida al rilevamento. quaderni del servizio geologico nazionale, serie iii, 1, 203 pp. fioraso g., lucchesi l. & forno m.l. (in elaborazione) stratigrafia. successione pliocenico-quaternaria. in: polino r., balestro g., cadoppi p., fioraso g., forno m. g., lucchesi s., piccardo g. b., spagnolo g.. & tallone s. note illustrative della carta geologica d'italia alla scala 1:50.000. foglio 155 torino ovest. apat servizio geologico d'italia/dipartimento difesa del suolo, roma. salvador a. (editor) (1994) international stratigraphic guide: a guide to stratigraphic classification, terminology, and procedure. 2nd edition. copublished by the international union of geological sciences and the geological society of america, boulder, colorado, 214 pp. servizio geologico d'italia (2001) indicazioni per il rilevamento del quaternario continentale. circolare carg disponibile sul sito web www.apat.it. servizio geologico d'italia (2002) carta geologica d'italia alla scala 1:50.000 e relative note illustrative. fogli 223 “ravenna”, 237 “sasso marconi”, 240-241 “forlì-cervia”. 55 ms. ricevuto il 2 aprile 2008 testo definitivo ricevuto il 17 aprile 2008 ms. received: april 2, 2008 final text received: april 17, 2008 le unità stratigrafiche di riferimento nella rappresentazione ... available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 109 112 palynological characterization of the po delta succession (northern italy): holocene vegetation dynamics, stratigraphic patterns and palaeoclimate variability marco cacciari 1 , veronica rossi 1 , marco marchesini 2 , alessandro amorosi 1 , luigi bruno 1 , bruno campo 1 1 department of biological, geological and environmental sciences, university of bologna, bologna, italy 2 laboratorio di palinologia e archeobotanica c.a.a. giorgio nicoli, san giovanni in persiceto, bologna, italy corresponding author: m. cacciari <marco.cacciari3@unibo.it> abstract: the 40 m-long core em2, recovered in the innermost portion of po delta plain, was sampled for palynological analysis, in order to link coastal-deltaic facies architecture to vegetation dynamics and holocene climate variability. pollen data refine facies characterization of the 25 m-thick holocene succession: freshwater swamp clays alternating with overbank/channel sands document millennial to centennial-scale water table oscillations that invariably peak in correspondence of peaty layers. pollen signature allows identification of the landward equivalent of the maximum flooding surface atop the 7.6 ka-dated peaty interval and furnishes new insights on the relationship between coastal facies patterns and climate events. keywords: palynology, holocene, po delta plain, climate events, sequence stratigraphy 1. introduction mediterranean delta plains are considered natural archives of the interactions between holocene depositional, climate and human dynamics. in these regions, the combined effect of high sea-level conditions, remarkable rates of subsidence and sediment supply led to the deposition of stratigraphically expanded, relatively continuous fine-grained sedimentary successions, useful for high-resolution palaeoenvironmental and stratigraphic reconstructions. the po delta plain is one of the most studied mediterranean deltas. a detailed characterization of sedimentary facies and a high-resolution sequencestratigraphic framework (with the identification of a set of millennial-scale parasequences) is available for the 1030 m-thick holocene succession (amorosi et al., 2017). however, the relationships between parasequence development and the well-known millennial-scale climate variability (bond’s events sensu bond et al., 1997) are still matter of debate. furthermore, palynology is a relatively unexplored stratigraphic tool for the identification of flooding surfaces within successions devoid of marine -influenced facies. through an integrated palynologicalstratigraphic approach, this study aims to reconstruct post-glacial stratigraphic patterns at the landward margin of the po delta and to unravel their relations with holocene climate events. 2. material and methods a 40 m-long core, recovered in the innermost portion of the po delta plain (core em2), was selected for palynological analysis, being composed of a ~25 m thick, chronologically well constrained (9 radiocarbon ages) paludal succession, framed into a robust stratigraphic context and dated to last ~13 ka (amorosi et al., 2017; bruno et al., 2017). thirty-seven samples were collected, with special focus on organic-rich, fine-grained intervals, where a rich palynological association was expected. about 3-9 g of dry sediment per sample were weighed and then a lycopodium tablet was added to calculate pollen concentration. samples were mechanically disrupted in a 10% na-pyrophosphate solution and filtered. then, each sample underwent the following treatments: 10% hcl solution, acetolysis, enrichment with a heavy liquid, 40% hf solution, ethanol suspension and evaporation at 60 °c. finally, microscope slides were prepared with glycerine jelly and paraffin. for each sample, at least 300 grains were counted and recognised after reille (1992). species ecological characterisation and pollen groups were based on pignatti (1982, 2017). on the other hand, non-arboreal pollen (nap) was split into herbaceous plants (h) and shrubs (sh) to better estimate the canopy thickness. 3. pollen sequence the em2 pollen spectra reported in fig. 1 confirm the persistence, at the study site, of freshwater conditions throughout the holocene (absence of halophytes) and highlight the vertical succession of fifteen pollen zones-pzs that correspond to distinct vegetation phases. in particular, a series of lateglacial-holocene climatic events were identified by combining high-frequency changes in relative abundance of specific pollen groups (fig. 1) with the available radiocarbon ages. all these events are marked by relative peak concentrations of montane trees-mt (6-10%) and/or cold steppe taxa-cst (3-8%), indicative of sudden cooling, sharply followed by https://doi.org/10.26382/aiqua.2018.aiquaconference 110 fig. 1 sedimentology and pollen characteristics of core em2: pt (pleistocene taxa), cf (conifers) mt (montane trees), cst (cold steppe taxa), m (mediterranean trees), q+other dt (mixed-oak forest and other deciduous trees), h (woody hygrophytes), hyg (herbaceous hygrophytes), hel (helophytes), hyd (hydrophytes), pm (pasture-meadow). facies: fl. ch. (fluvial channel), distr. ch. (distributary channel), crs (crevasse splay), fpl (floodplain), pdf (poorly-drained floodplain), sw (swamp). the “p” subscript indicates a weakly pedogenised deposit. ps: parasequence (light blue lines are parasequence boundaries; dotted lines indicate minor flooding surfaces). mfs: maximum flooding surface. sb: sequence boundary from bruno et al. (2017). cacciari m. et al. 111 high percentages of climate optimum indicators (i.e., holm oak-mixed-oak forest, m-q+other dt) within a relatively continuous stratigraphic interval, a few tens of centimetres thick. along the core, conifers show similar vertical variations relative to mt+cst and, thus, were interpreted as a regional pollen rain, analogous to the cold indicators sensu stricto. the oldest cold spell (pz 13), chronologically attributed to the younger dryas event, occurs within the uppermost portion of the fluvial channel succession deposited under glacial-lateglacial conditions (amorosi et al., 2017; pzs 14-13) and observed between ~35.5-26 m core depth (fig. 1). the overlying, 25 m-thick sedimentary succession, composed of alternating swamp clays and overbank/ channel sands is assigned to the holocene period, based on combined radiocarbon ages and pollen data (pzs 12-1), the latter reflecting an overall climateoptimum-like vegetal landscape. however, three distinct phases of rapid cooling are recognised and reasonably ascribed to the preboreal oscillation (pz 11), boreal oscillation (pz 9) and 8.2 ka event (pz 7), respectively. more uncertain are dating and interpretation of other two cooling events recorded by pzs 5 and 3. finally, a relatively high concentration of mt and cst (7% total), paralleled by a sharp decrease in holm oak (from 13% to 1%), is recorded at the top (1 m) of the cored succession, within pedogenized floodplain deposits, possibly documenting the little ice age event. 4. holocene vegetation dynamics and facies stacking patterns the palynological analysis also refines facies characterization, especially of fine-grained deposits, allowing the distinction between poorly drained floodplain facies, characterised by the absence or scarcity of helophytes and hydrophytes, and swamp clays. moreover, two types of swamp deposits were identified within the holocene succession on the basis of the relative abundances of woody and herbaceous hygrophytes, helophytes and hydrophytes: peaty swamp (sw1): herbaceous wetland community with sparse alder carrs tolerating prolonged periods of radical drowning (helophytes) or aquatic plants (hydrophytes); subordinate hygrophytes, poaceae and alder (mixed or not) bordering the locally flooded depressions. this pollen assemblage, invariably recorded within peaty layers (~10-30 cm thick), indicates relatively high water table conditions. swamp (sw2): open to dense alder carr with a mixed oak-holm oak ecological component in subordinate position. this pollen assemblage, found within organic-rich grey to dark grey clays, documents a relatively low water table. throughout the holocene succession, sw1 peats are vertically constrained between sw2 clays, which in turn are commonly overlain by crevasse splays or distributary-channel sandy deposits containing a pollen assemblage indicative of a hygrophilous, open to dense mixed oak-holm oak forest. this repeated stacking pattern of facies tracks short-term (millennial to submillennial scale) oscillations in the relative water table, allowing the identification of small-scale, t-r depositional cycles (i.e., parasequences bounded by flooding surfaces-fss) in a fully freshwater sequence. specifically, each cycle is composed of basal sw2 grey-dark grey clays, commonly showing an upward increase in dispersed organic matter, and culminates into a peaty interval (sw1 that reflects the most drowned conditions). upwards, a shallowing-upward trend is identified by pollen data, marking the progradational part of the parasequence (ps). furthermore, an overall increase in water table was recorded from the oldest swamp (dated around 11455±195 cal yrs bp) to the swamp recorded at ~13.35 m core depth and dated to 7675±75 cal yrs bp. this deepening-upward trend is considered as the sedimentary expression of the maximum flooding surface mfs at proximal locations. upwards, swamps generally show less developed peat accumulation and a lower water table relative to the underlying transgressive swamps. 5. discussion and conclusions diagnostic changes in vegetation patterns enable the precise documentation of parasequence development at the landward margin of the po delta plain during the holocene. therefore, because of the absence of meiofauna and molluscs in this freshwater paludal succession, the sequence-stratigraphic refinement at a millennial – sub-millennial scale was performed by palynological analysis. throughout core em2, the relative abundances of woody and herbaceous hygrophytes, helophytes and hydrophytes record alternating periods of rising water table (i.e., flooding events), which peak in correspondence of cm to dm-thick peaty swamp intervals (i.e., the most drowned conditions within each ps), and which subsequently decreases. the highest relative water table was reached atop the peaty swamp deposit belonging to ps 4 and dated to ~7600 cal yrs bp (fig. 1), which separates a set of transgressive parasequences from the highstand ones. highstand parasequences are characterised by the development of peaty swamp intervals under lower water table conditions, reflecting the general progradation of the po delta system during the mid-late holocene. these data, supported by the chronological and the stratigraphic frameworks available for the entire study area (amorosi et al., 2017; bruno et al., 2017; campo et al., 2017), suggest a strong allogenic control (i.e., glacio-eustatic oscillations at the milankovitch time-scale) on depositional dynamics ca. 35 km upstream from the modern coastline. a unique exception is the uppermost peaty layer, recorded at 3 m core depth and dated to ~1000-1100 cal yrs bp, which reflects the local establishment of a high water table possibly related to the historical po river avulsion in ficarolo. the northward shift of the po river system and the subsequent marked reduction in sediment supply reasonably induced the flooding of the southern portion of the subsiding po delta plain, where em2 core was recovered. the comparison between stratigraphic and pollenderived climatic data documents a complex interaction between parasequence development and holocene climate events. not all peats (sw1-peaty swamps) devel holocene palynology of the po delta succession oped under mild conditions, suggesting the influence of other driving mechanisms, such as early holocene eustatic jumps (mwp-melt water pulse) and autogenic factors. on the other hand, the thick alluvial successions in the uppermost portions of pss 2, 3 and 6 saw the development of cool-temperate communities, the eldest of which was chronologically constrained to the 8.2 ka event. as a whole the three pss suggest a strong sedimentary response to these short-term phases of climatic cooling in terms of increased sedimentary input and partial filling of paludal basins. acknowledgements this project, supported by rfo funds at university of bologna-italy (aa and vr), was possible thanks to a collaborative research project supported by exxonmobil upstream research company (grant to a. amorosi) and to the strong collaboration with centro agricoltura e ambiente “g. nicoli” laboratory (san giovanni in persiceto, bologna). references amorosi a., bruno l., campo b., morelli a., rossi v., scarponi d., hong w., bohacs k. m., drexler t. m. (2017) global sea-level control on local parasequence architecture from the holocene record of the po plain, italy. marine and petroleum geology, 87, 99-111. bond g., showers w., cheseby m., lotti r., almasi p., demenocal p., priore p., cullen h., hajdas i., bonani g. (1997) a pervasive millennial-scale cycle in north atlantic holocene and glacial climates. science, 278, 1257-1266. bruno l., bohacs k.m., campo b., drexler t.m., rossi v., sammartino i., scarponi d., hong w., amorosi a. (2017) early holocene transgressive palaeogeography in the po coastal plain (northern italy). sedimentology, 64, 1792-1816. campo b., amorosi a., vaiani s.c. (2017) sequence stratigraphy and late quaternary paleoenvironmental evolution of the northern adriatic coastal plain (italy). palaeogeography, palaoclimatology. palaeoecology, 466, 265-278. pignatti s. (1982) flora d’italia. edagricole, bologna, italy. pignatti s. (2017) flora d’italia, 1-2. edagricole, bologna, italy. reille m. (1992) pollen et spores d’europe et d’afrique du nord. laboratoire de botanique historique et palynologie, marseille, france, pp. 331. 112 cacciari m. et al. ms. received: may 10, 2018 final text received: may 23, 2018 microsoft word 00_indice_06lm.docx il quaternario it issn 039-3356 italian journal of quaternary sciences 24 (2), 2011 193-198 considerations on an integrated biochronological scale of italian quaternary continental mammals federico masini1 & benedetto sala2 1 dipartimento di geologia e geodesia, università di palermo, palermo 2 dipartimento di biologia ed evoluzione, università di ferrara, ferrara corresponding author: benedetto sala <benedetto.sala@unife.it> abstract: abstract: masini f. & sala b., considerations on an integrated biochronological scale of italian quaternary continental mammals. the paper of masini and sala (2007) regarding an integrated approach on the stratigraphic distribution patterns of large and small mammals in the late pliocene and pleistocene of the italian peninsula is analysed, showing the weak and strong points. new data are presented on the mammal biochronology of the late pleistocene riassunto: masini f. & sala b., considerazioni su una scala biocronologica integrata dei mammiferi continentali quaternari in italia. viene analizzato il lavoro di masini e sala (2007) sull’approccio integrato della distribuzione dei grandi e piccoli mammiferi dell’italia continentale del tardo pliocene e del pleistocene, tenendo conto della nuova definizione del quaternario, mettendo in risalto i punti di forza e quelli deboli della scala proposta. vengono inoltre aggiunti nuovi dati sulla biocronologia a mammiferi del pleistocene superiore. keiwords: biochronology, mammals, quaternary, italian peninsula. parole chiave: biocronologia,mammiferi, quaternario, italia continentale. despite the marginal geographical position of the italian peninsula in the eurasian continent, italian quaternary deposits have yielded a good succession of well diversified fossil mammal assemblages. the effect of the quaternary climatic changes on faunal associations was moderate due to the gentle effect of the sea. however, there are important differences between the ligurian tyrrhenian coast and the adriatic coast, which interrelate with the significant latitudinal extension and complex geomorphological setting of the peninsula (sala 2002; sala and marchetti 2006). this diverse geographical situation allowed some species to use specially protected areas as refuges during very cold climatic phases. mammalian biochronology has a certain tradition in italy thanks to the pioneering works of azzaroli (1977). villafranchian and galerian large mammal ages, mainly defined on the italian succession of large mammal faunas, are of common use in italy as well as in some other european countries. however, the so called holarctic biochronological scale based on small mammal faunas, mostly arvicolids, is most widespread for the plio pleistocene of europe and the former soviet union. this contribution is a revision of an updated version of the biochronology proposed by masini and sala (2007), sala and masini (2007), in which large and small mammals scales are correlated (the references of the sites here cited are referred to the former paper). the adopted large mammal biochronology is that pioneered by azzaroli (1977), and further developed mainly by italian students; the small mammal scale is that of fejfar and heinrich (1990). correlation presents some difficulties, as only few deposits of the early pleistocene and part of the middle pleistocene have valid documentation of mammals of both classes of size. the complexity of the correlations is also influenced by many taphonomic factors and by different approaches to the study of the two groups of mammals (e.g. sala 1983; palombo 2004; masini and abbazzi 2004). the adopted chronostratigraphical frame is that of gibbard et al (20052007) according to gibbard and head (2009) and gibbard et al (2009) definitions. recently, palombo (2009) focuses on the differences between biochronology and biostratigraphy, and bases her chronological framework on large mammals, reporting advantages and deficiencies. the use of large mammals data does not allow, for example, to recognize the age of valdemino faunal assemblage (lower layers), which is included, for the small mammals, in the lower toringian for the occurrence of arvicola mosbachensis and the lack of mimomys savini, while it is incorrectly referred to the slivia fu by palombo 2009. this author does not accept the saint vallier fu because not well documented in italy and encloses the faunal remains of this unit in costa s. giacomo fu. the base of the quaternary period corresponds to the beginning of the middle villafranchian (montopoli faunal unit = fu) large mammal age, and roughly to the end of the early villanyian small mammal age. the deposit of montopoli (pisa), which occurs at the gaussmatuyama transition (lindsay et al. 1980), however, is not preceded by adequate documentation of the faunal transition from early villafranchian and only yielded large mammal remains. other sites of this fu (bocchimasini f. & sala b. 194 gnano, rieti; vinci, pisa; montecarlo, firenze; anagni, frosinone) contain scant assemblages. the second part of the middle villafranchian is documented by sporadic finds, possibly representing the st. vallier fu (e.g. castel viscardo, orvieto) and by the fauna of the costa san giacomo fu. the rich micro-teriofaunas of rivoli veronese (verona) and montagnola senese (siena) well document the occurrence of the late villanyian in italy and correlate with the latest part of the middle villafranchian, even though the lack of significant large mammal finds in these localities does not allow a direct correlation. the transition to the olivola fu (early late villafranchian) is quite gradual, as it is that to the next tasso fu. monte la mesa (verona) yielded a very rich small mammal fauna, referable to the early part of the early biharian, and likely correlated to the tasso fu. the scant remains of large mammals at monte la mesa, however, again highlight the correlation problems mentioned above. the magnetostratigraphic correlations of the faunas of this part of villafranchian are based almost exclusively on findings in the upper valdarno basin, where the sediments containing fauna of tasso (arezzo) refers to the top of the sub-magnetochrone olduvai and thus are placed at the base of the second part of early pleistocene (calabrian). the fu of farneta and pirro include early biharian micro-fauna (pietrafitta, cava pirro dell'erba, soave cava sud) found together with rich late villafranchian large mammal assemblages, thus giving a direct correlation between the two biochronological scales. a calibration for these two faunal units is lacking, but the evolutionary stages of some taxa (allophaiomys) allow to propose a dating around 1.5 and 1.3 ma respectively. the colle curti (macerata), castagnone (alessandria) and monte peglia (perugia) localities are attributed to the sub-magnetochron jaramillo. they contain large mammals of the beginning of the galerian age (colle curti fu) and small mammals of late early biharian. the following early galerian slivia fu yielded typical late biharian microfaunas, where microtus (allophaiomys) is absent and mimomys savini is associated to more advanced species of microtus. the small mammal fauna of rifreddo (potenza) belongs to the same fu and is correlated to the lower part of brunhes chron. documentation becomes richer during the middle galerian. the most important sites are isernia la pineta (isernia), valdemino cave (savona), visogliano (trieste), deeper layers, and venosa-notarchirico (taranto). the middle galerian coincides with the beginning of toringian, characterised by the substitution of mimomys savini by arvicola mosbachensis. this transition is linked to climate change, with the appearance of more arid environments, at least seasonally, determining greater differences between “cold” and “warm” faunas within the glacial-interglacial cycles. palaeomagnetic and radiometric dating are available at isernia and notarchirico. the climatic and faunal changes lead to the late galerian fauna, represented by the fontana ranuccio fu. the small mammal faunas, e.g. boscochiesanuova (verona), loara and commenda (vicenza) (bartolomei 1969, 1980) belong to the early toringian, while large mammal faunas are difficult to be placed chronologically, since they poorly differ from the previous ones. the increase in climatic differences between warm and cold periods, the beginning of a marked regionalism, the similarity of the faunas, especially during warm periods, and the lack of “absolute” dating introduce some uncertainties when assigning the chronology of the deposits. the spread of faunas with cold affinities (e.g. the occurrence of the modern wolf, the boreal lynx and the ibex) indicates the beginning of the aurelian mammal age (or post-galerian). we are approaching to the end of the middle pleistocene, and the increased documentation, the regional differences, the intensity of climatic oscillations require finer chronological detail. from this moment on, the utility of the faunal unit falls short, in favour of marine isotope stages (mis) which scan the chronology of the major climatic fluctuations very well. sites with transitional faunas and those referred to the beginning of the aurelian yielded mammals of warm environments. most important ones are in latium (riano, castel di guido, malagrotta, polledrara of cecanibbio), where the arrival of a bubalus of asian origin is reported, thus indicating one or more “hot" climatic oscillations. bubalus arrives twice in germany, during the steinheim interglacial (holstenian), and later during the eemian (koenigswald 1986). the faunal association from steinheim includes mammals such as bubalus murrensis, palaeoloxodon antiquus, bos primigenius, megaloceros giganteus, stephanorhinus kirchbergensis (czarnetzki 1983) that are also found in latium faunal assemblages; likely the latter faunas should be referred to mis 7. palombo et al. (2004), however, according to their interpretation of the sequence stratigraphy of the roman basin, suggest a correlation with mis 9 for torre in pietra 1, monte delle gioie, sedia del diavolo, polledrara of cecanibbio and castel di guido, and with mis 7 for vitinia, quartaccio and torre in pietra 2. the cold faunas are affected minor uncertainty. the sequences of poggio cave and of grotta grande sector c. of scario (salerno), the outer levels of paglicci cave (foggia) and san bernardino cave (vicenza) and the r and s layers of broion cave (vicenza) contain faunas dominated by first cold mountain goats arriving in the italian peninsula, capra ibex, and are referred to mis 6. the transition between early and late toringian is somewhat blurred in the italian peninsula due to the possible co-occurrence of two species of arvicola. recently, petronio et al. (2007) proposed two new faunal units for the late aurelian but, as reported above, especially for the regional differences during this period, we are unfavourable to the use of faunal units for assemblages younger than mis 7 and we do not accept this proposal. moreover, the use in biochronology of the occurrence of not easy recognizable subspecies, such as dama dama dama, and of mammals which are very rare in italy, such as coelodonta antiquitatis, to define a fu is not applicable. in masini and sala (2007) the late pleistocene was scantily reported and commented, so we provide here with new data. the last interglacial (eemian, mis 5e), which marks the beginning of the late pleistocene, is documented by the sediments of some coastal caves containing remains of large vertebrates and recently yielded the remains of small mammals, e.g. the deepest levels of cavallo cave (lecce). there are, however, some temperate faunas ascribed to a generic mis 5, e.g. san sidero 3 (lecce) and grotta grande of scario s.a. (salerno).   considerations on an integrated biochronological scale … 195 tab. 1: integrated stratigraphic scheme for the quaternary large and small mammalian record of the italian peninsula. schema stratigrafico integrato del quaternario per il record dei grandi e piccoli mammiferi della penisola italiana masini f. & sala b. 196 tab. 2: integrated stratigraphic scheme for the mis 6-1 large and small mammalian record of the italian peninsula. schema stratigrafico integrato del mis 6-1 per il record dei grandi e piccoli mammiferi della penisola italiana the iiird level of caverna delle fate (savona) is assigned by psathi (2003) to mis 5, but quilès (2003), using the p4 morphometric index of ursus spelaeus (rabeder 1999), infer an age of 90 ka, roughly corresponding to mis 5c or 5a. the faunal assemblage from madonna dell’arma and from the lower levels of grotta del principe (imperia), considered coeval, are referred to mis 5c or 5a (valensi 2009). in two papers on large (rubinato 2009) and small mammals (berto 2009) from caverna degli orsi (trieste) the stratigraphic units 14.1 of the sector a and 125-122 of the sector b are ascribed to the temperate oscillation of mis 5a. during the mis 5, in italy, and probably also in all the europe, palaeoloxodon antiquus and hippopotamus are still quoted, but not during mis 4, probably due to the first climatic rigours of the last glacial (wurmian). dama dama, abundant in mis 5e, becomes rarer in mis 5c-a but it is present also e.g. at caverna degli orsi, in the north-east, where the environment was less temperate then in other parts of the peninsula, in plane or at the foot of the mountains. the levels iiib of caverna delle fate, the upper levels of grotta del principe, the levels iv÷i of arma delle manie (savona) are assigned to mis 4 (valensi 2009). some other sequences of caves and shelters with mousterian industries and rich of faunas are ascribed to this stage, e.g. upper layers of ghiacciaia cave (verona) (sala 1990). many other sites bear long sequences with mousterian industries but dating are scarce. after 50 ka, the 14c radiometric dating are of assistance for the chronology and recently also tl dating and u/th-esr combined dating are used above all in prehistoric sites. an example is supplied by peresani et al. (2008), in which uluzzian levels of fumane cave and others sites in the eastern italian pre-alps, slovenia and croatia are quoted with those methodologies to mis 3 (layers i of broion cave, rio secco cave, layers b through e1 and ei/e2 of munjina pećina, level g3 of vidinja cave and others). other prehistoric localities are attributed to mis 3, e.g.mezzena shelter (verona) (giunti et al. 2008). later, with the appearance of the upper palaeolithic industries and their undoubted chronological value, the dated layers are very numerous. if the referral to isotopic stage is adopted, the sub-stage should be specified, because the minor climatic oscillations occurring within a stage are reflected in changes in faunal associations. the geographic location of the site must also be considered with the highest regard, because of the occurrence of regional faunal differences and since even small changes in altitude or topography of the area determined important differences in the assemblages of both micro-and macro-mammals. the sequence of the castelcivita cave records the mousterian late paleolithic transion; the rich faunal assemblages (masini & abbazzi, 1997) are well representative of the mammalian populations of the middle to late part of mis 3 (substages mis 3,12 to mis 3,01, sensu pisias et al. 1984; paterne et al. 1986) at the tyrrhenian side of the peninsula (napoleone et al. 1997). in the mis 3 some mammals are present for the last time, e.g. dama dama in the aurignacian levels of the cala cave (benini et al. 1997), mammuthus primigenius and megaloceros giganteus at settepolesini di bondeno (ferrara) (gallini and sala 2001). mis 2 is well documented in italian peninsula and some papers furnish information on faunal assemblages considerations on an integrated biochronological scale … 197 of the last glacial maximum (sala 2004 and references in it) or of the late glacial (sala 2007 and references in it) of numerous sites of the whole italian peninsula. among the carnivores, the occurrence of crocuta spelaea is noted for the last time in the ancient epigravettian layers of paglicci cave (boscato and palma di cesnola 2000). the mammal faunas of the ancient holocene also are well known and come from mesolithic and neolithic sites. in the holocene the reduction of biodiversity is only partially compensated by the arrive of martes foina, micromys minutus, mus domesticus and later of rattus rattus, rattus norvegicus; very recently apodemus agrarius, erinaceus concolor and canis aureus begin to spread in the north-eastern of italy. references azzaroli, a., 1977. the villafranchian stage in italy and the plio-pleistocene boundary. giornale di geologia, 41, pp. 61-79. bartolomei g. 1969 primi contributi alla conoscenza dei dolomys pleistocenici del veneto e del carso. mem. mus. civ.st. nat. verona, 17, pp. 79-139, 32 figg. bartolomei g., 1980 i micro mammiferi del plio-pleistocene. in: aa.vv. “i vertebrati fossili italiani, catalogo della mostra”. 1980, pp. 249-258, verona. benini a., boscato p., gambassini p.1997 grotta della cala (salerno): industrie litiche e faune uluzziane ed aurignaziane. rivista di scienze preistoriche, 48, pp. 37-95. berto c. 2009 la caverna degli orsi a san dorligo della valle dolina (trieste). una serquenza würmiana a micromammiferi. tesi di laurea specialistica in scienze preistoriche, univ. di ferrara. boscato p., palma di cesnola a. 2000 nuovi ritrovamenti di epigravettiano antico "iniziale" a grotta paglicci (rignano garganico, foggia). società preistoria protostoria friuli-venezia giulia, trieste, quaderno, 8, pp. 45-61. czarnetzki a.,1983. zur entwicklungdes menschen in südwestdeutschland. in: müller-beck (ed): “urgeschichte in baden württemberg”, pp. 217-240, stuttgart: theiss. fejfar o., heinrich w.d, 1990, muroid rodent biochronology of the neogene and quaternary of europe. in: e.h.lindsay, v. fahlbusch and p.mein (eds.) “european neogene mammal chronology”, pp. 91-116, plenum press, new york – london. gallini v., sala b. 2001 settepolesini di bondeno (ferrara eastern po valley): the first example of mammoth steppe in italy. in: cavarretta g., gioia p., mussi m., palombo m.r. 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(ed.) “l’italia tra 15.000 e 10.000 anni fa cosmopolitismo e regionalità nel tardoglaciale”. millenni, studi di archeologia preistorica 5, pp. 21-38, museo fiorentino di preistoria “paolo graziosi”, firenze. sala b., marchetti m. 2006 the po valley floodplain (northern italy): a transitional area between two zoogeographical areas during the late neogene and quaternary. cour. forsch.-inst. senckenberg, 256, pp. 321-328, frankfurt a.m. sala b, masini f. 2007 the late pliocene and pleistocene small mammal chronology in the italian peninsula. quaternary international, 160/1, pp. 4-16. valensi p. 2009 évolution des peuplements de grands mammifères en europe méditerranéenne occidentale durant le pléistocène moyen et superieur. un exemple régional: les alpes du sud françaises et italiennes. quaternaire, 20 (4), pp. 551-567. ms. ricevuto il 13 luglio 2010 testo definitivo ricevuto il 19 dicembre 2010 ms. received: july 13, 2010 final text received: december 31, 2010 ostermann et al 183-189.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 33 (2), 2020, 183-189 characteristics and dating of the rock avalanche at pragser wildsee/lago di braies (dolomites, italy). marc ostermann 1, susan ivy�ochs 2, frowin ruegenberg 3, christof vockenhuber 2 1 geological survey of austria, vienna, austria. 2 ion beam physics, eth, zurich, switzerland. 3 department of geology, university of innsbruck, innsbruck, austria. corresponding author: m. ostermann <marc.ostermann@geologie.ac.at> abstract: major gravitational slope deformations are widely disseminated in the dolomite mountains (ne italy), one of the world's most conspicuous landscapes and part of the unesco world heritage list. in the prags valley a rock avalanche still dams a backwater lake the pragser wildsee/lago di braies. the volume of rock debris accumulations comprise approximately 30-40 106 m³ of mainly dolomitic rock and the area covered by rock debris is about 3.5 km². the run-out distance of about 8.5 km and a maximum vertical drop of 1150 m (h/l-ratio: 0.13) yield a run-out travel angle (fahrböschungswinkel) of 8°. especially in the surrounding of schmieden/ferrara a hummocky landscape with numerous hills and ridges is developed. here some classical toma hills are encountered, i.e. isolated coneto pyramidalor roof-shaped hills composed of rock avalanche debris. mainly because assumptions about the origin of this hummocky landscape has been related to glacial processes, the formation of pragser wildsee was previously thought to be of lateglacial age. we applied cosmogenic 36cl surface exposure dating of four boulders within the debris accumulations and obtained an early holocene age of 8.3±0.7 ka for the event. our findings go along with the results of published radiocarbon dates from sediment-drillcores within the backwater lake, which indicate a recalibrated minimum age for the slope failure of 7410±100 cal years bp (irmler, 2003). the accumulations at pragser wildsee show strong similarities to the obernberg rock avalanche in geomorphology as well as in age, making them the first examples of early holocene rock avalanches forming toma hill landscapes. keywords: rock avalanche, early holocene, cosmogenic nuclide dating, toma hills, pragser wildsee/lago di braies, dolomites. � 1. introduction in the past, several hypotheses have been formulated regarding the formation of the pragser wildsee/ lago di braies. although it was clear that the lake was dammed by debris deposits, their origin was controversial. it was especially the hilly valley bottom morphology downriver of the lake itself that caused speculations. according to damian (1899), hantke (1983) and heiss (1992), a huge debris flow fan, spreaded from the riedl valley (figs. 1, 2), together with smaller landslides and rock falls gave rise to the damming of the lake. another hypothesis considered the wide deposits as glacial (dal piaz 1930; pia, 1937) or composed of landslide masses subsequently transported and rearranged by a glacier (klebelsberg, 1927, 1935, 1956; castiglioni, 1964; engelen, 1972). abele (1974) instead assumed that pragser wildsee/lago di braies was dammed by a massive rock slope failure event. recently, the deposits have been described more in detail by furlanis (2013) and in the comments to the recently published geological carg map sheet 016 toblach/dobbiaco (gianolla et al., 2018). the reclassification of deposits previously misidentified as having origins other than landsliding has been done commonly in the last decades (e.g. spreafico et al., 2018). here, we describe the results of an extensive fieldwork, including sedimentological, morphological analyses and dating of the rock avalanche in the prags valley. 2. methods field mapping was conducted on a scale of 1:5000 using topographic maps and airborne laserscan images in 10 m resolution provided by the autonomous province of bolzano south tyrol. geometric calculations including volume estimations were made with autocad 2014. the estimations of the deposit thickness is based on the information from a 20 m long drill core conducted by the geological survey of south tyrol (fig. 3). for exposure dating with 36cl in the proximal sector of the rock avalanche, the surfaces of four boulders were sampled (tab.1). sample preparation is described in ivy-ochs et al. (2009). 36cl and natural cl (isotope dilution; ivy-ochs et al., 2004) were determined with https://doi.org/10.26382/amq.2020.07 184 ostermann m. et al. accelerator mass spectrometry (synal et al., 1997). major element and minor concentrations (tab. 2) were used to determine 36cl production rates (alfimov & ivyochs, 2009 and references therein). the radiocarbon age published by irmler (2003) were re-calibrated with oxcal 4.3 (bronk ramsey, 2009). 3. geological framework the prags valley/braies valley is located in the northeastern part of the dolomites, which are part of the southern alps. the dolomites consist mainly of the marine sediments of the upper permian and triassic periods, which were deposited in tropical to subtropical climate on permian volcanic rocks and, as in the vicinity of the puster valley, on metamorphic crystalline basement rocks (brandner et al., 2007b) (fig. 2). regarding to the pragser wildsee rock avalanche there are three lithologies within the permo-mesozoic sediment succession (fig. 2) which are important to describe more in detail, because these are the formations involved in the phenomenon. the buchenstein formation: pelagic basin sediments that interlock with the clinoforms of the prograding ladinian carbonate platforms (brandner et al., 2007b). the limestones of the buchenstein fm. is well-bedded (cm-dm), partly bituminous and laminated (keim, 2008). thin volcanogenic clastics “pietra verde“-layers (cm-dm) are interbedded decreasing the mechanical properties of the whole succession. the schlern formation consists of preand postvolcanic carbonate rocks, which formed mighty reefs or their clinoforms in the ladinian. the reef slope interlocks with the basin sediments of the buchenstein formation. the rocks were formed in a tropical subtropical climate (muttoni et al., 2003) in marine shallow waters and later dolomitized, whereby the coarse banking is relatively unclearly recognizable (pia, 1937). the fernazza formation corresponds essentially to the basin-deposits of the proximal, alkaline volcanic activity in the dolomites. the most common lithotypes are volcanoclastic, turbiditic, massive sandstones, homogeneous or graded, dark green to blackish colour, greenish tuffites of the "pietra verde" type, siliceous tuffites, hyaloclastites and laminated calcareous siltites. laminated, siliceous calcareous lutites, hemipelagites and marls are also found in between. at the top of the fig. 1 distribution of major mass movements in the western dolomites, italy, indicated on a hill-shade image (acc. to ostermann & gruber, 2014, based on brandner et al., 2007a). dsgsd stands for deep-seated gravitational slope deformation. the insert-map shows the assumed maximum extent of the rock avalanche with removed post-failure accumulations (mainly debris flow fans). the red line represents the scarp. 185 characteristics and dating of the rock avalanche at pragser wildsee/lago di braies (dolomites, italy) fig. 2 geological map of prags valley (modified detail of the carta geologica d'italia alla scala 1:50.000, map sheet 016 toblach/ dobiaco). in magenta the nowadays outcropped debris accumulations are highlighted. a-c indicate the three different accumulation areas mentioned in the text. scs: st. kassian fm.; scia: schlern fm. in reef facies; imf: fernazza fm.; dcs: kassianer fm.; buc: buchenstein fm.; mtb: ambata fm.; don: dont fm.; wen: wengen fm.; the full legend can be found in gianolla et al., 2018. the black line indicates the thrust fault separating the permo-mesozoic sediments succession in the south from the metamorphic basement in the north. the green line indicates the orientation of the schematic cross-section (insert figure, 2 x super-elevated). fig. 3 hillshade image of the prags valley with indicated rock avalanche accumulations in magenta: light magenta for the maximum extent of the accumulations, dark magenta indicates the accumulations as drawn in the geological map. red line: main scarp. the yellow circle indicates the location of a 20m long drilling, conducted by the south-tyrolian geological survey. the insert photo, view towards north, shows the pragser wildsee in the foreground and the riedl valley and the prags valley with indicated debris accumulations in the background. the insert-map shows a detail of the hillshade with 10 m contour lines and the sampling points for surface exposure dating with obtained 36cl ages. 186 ostermann m. et al. fernazza fm. fine-grained calcarenites and marly limestones are present. 4. characterisation of the rock avalanche scarp and the slope failure accumulations 4.1. characteristics of the scarp area the scarp area of the rock avalanche is located in the upper part of the riedl valley at elevations between about 2000 and 2350 m a.s.l. (fig. 3). schlern fm. is the prevalent formation in the crown area which is also reflected in the lithological composition of the debris accumulations. along the southern and south-western flank of the riedl valley, here a well-banked schlern fm. is exposed. the banks dip with � 60° towards s-sw (more or less parallel to the northern slope) represented a predisposing factor for a dip slope slide (e.g. abele, 1974; hoek & bray, 1981). the schlern fm. also shows pronounced jointing and partly karst-widened cracks, which were already mentioned by pia (1937). there are several tectonic lineaments, in different orientations, nearby the scarp area (fig. 2) and many rock slope failures show these tectonic constrains (e.g. stead & wolter, 2015), but we could not find convincing evidence for tectonic lineaments that delimited the failed rock mass here. according to the map of van husen (1987) the lgm-ice surface in the prags valley was between 2300 and 2400 meters a.s.l., which hints that the scarp area at least was partly covered with ice during this period. 4.2. characteristics of the rock avalanche accumulation area the accumulation area of the rock avalanche at pragser wildsee can be divided into three distinguishable areas (a-c) (fig. 2 & 3). a) area a refers to the proximal deposits in the riedl valley. here the deposits are mainly (>95%) composed of schlern fm. blocks, which are strongly weathered and can reach several tens of cubic meters in volume lying on top of finer material (carapace facies). the accumulations are partly overlaid by deposits of secondary landslides coming from the north (shallow landslides, slope debris). in the southern part of the riedl valley, debris flows accumulation overlay the rock avalanche deposit, mainly consisting of reworked and relocated landslide material. b) accumulation at area b (fig. 2 & 3) is located on the west side of herrstein and forms a proximal surge barrier with a maximum total thickness of about 150 m, which was created under high-energy conditions on the opposite slope. the sediments here consist of a massive, matrix-supported diamict with a loose and fig. 4 hillshade image of the outer prags valley with highlighted toma hills and debris ridges (magenta). the arrows indicate the travel path of the rock avalanche. on the insert photo, view towards southwest, the scarp is indicated with a dashed line in magenta and the accumulations with a dashed with line. in the foreground the toma hills and ridges are accentuated. partially open framework structure. blocks and megablocks of massive dolomites are found, the matrix is gravelly and slightly sandy. all components are from angular to sub-rounded. it represents the main accumulation zone of the rock avalanche and it is primarily responsible for the damming of the lake. the morphology can be described as very unsettled. on the surface, there are dark weathered blocks of schlern fm., up to several 10 cubic metres in size, in nonexposed areas the blocks are angular. landslide material is also found on the nw shore of the lake below the debris cone from the riedltal valley, which was confirmed by sediment-echographic investigations (irmler, 2003). c) area c represents the distal part of the rock avalanche deposits in the prags valley and it is primarily characterized by the presence of undulating relief known as toma hills. their genesis is directly connected to the rock slope failure event. the prags valley therefore is a very beautiful example of a socalled toma landscape (penck & brückner, 1901; abele, 1974). in many places the landslide material is overlain by debris flow and alluvial material from the side valleys, but can be traced back up to the sports 187 characteristics and dating of the rock avalanche at pragser wildsee/lago di braies (dolomites, italy) field north of the village of schmieden/ferrara (fig. 4). within the accumulation area c the thickness of the deposit was estimated to be only 5 m. beside some blocks of schlern fm. in meter scale, there are mostly poorly sorted, angular components in cm-dm size. the average size is therefore finer than the material at accumulation area b. contrary to older assumptions (e.g. klebelsberg, 1935; pia, 1937; castiglioni, 1964; abele, 1974) the rock avalanche material in the prags valley was not transported by a glacier out of the valley. there is no evidence of glacial transport, nor of glacial overlay. 4.3. geometrical characteristics of the pragser wildsee rock avalanche rock avalanche deposits exposed at the surface cover an area of ~1.7 km2. taking into account those parts of the avalanche that are buried by alluvial fans, talus slopes and colluvium, an area of ~3.5 km2 was estimated. the distance from the upper limit of the detachment scarp (2330 m a.s.l.) to the most distal toma hill (1180 m a.s.l.) is 8.5 km, yielding a fahrböschung angle of 8°. according to our calculation based on a digital elevation model, the total volume of rock avalanche deposits is 36 million m³, so a volume between 30 and 40 million m³ can be given. 5. dating the pragser wildsee rock avalanche for exposure dating with 36cl, in the proximal sector of the rock avalanche (accumulation area b), the surfaces of four boulders of schlern dolomite were sampled (locations in insert map in fig. 3). unfortunately, the distal sector of the avalanche deposit (accumulation area c) with transversal ridges and toma hills is devoid of suitable boulders (those lying well above the enclosing sediment). we obtained the following exposure ages: 7.82 ±0.45 ka (prag1), 8.18 ±0.55 ka (prag2), 8.89 ±0.76 ka (prag3), and 8.28 ±0.64 ka (prag4). sample site and dating information is given in tab. 1 and the chemical composition of the samples in tab. 2. the average age of 8.3 ±0.7 ka indicates an early holocene age for the rock avalanche event. tab. 1 sample information, ams data and calculated exposure ages. exposure ages were calculated using stone et al.(1996, 1998) production rates (see also alfimov & ivy-ochs, 2009) and lal /stone scaling (stone, 2000). no erosion correction was made. tab. 2 chemical composition of analysed rock samples, major oxides in wt %, trace elements in ppm. tab. 3 major parameters of the rock avalanches at pragser wildsee and obernberg. at the base of a 12.1 m long drill core a tree needle was found during the investigations of the lake deposits by irmler (2003). its age was determined by 14c dating. the age was determined to 6504 ±47 uncal. years bp which corresponds to a calibrated 14c age of 7410 ±100 cal. years bp. this age can be regarded as the minimum age of the lake and therefore as a minimum age of the landslide. 6. discussion the pragser wildsee/lago di braies rock avalanche shows conspicuous similarities to the obernberg rock avalanche (ostermann et al., 2012) situated about 60 km in the nw of the prags valley within the brenner mesozoic (eastern alps, austria). both rock avalanches show runout paths with a runup/impact on the opposite slope and a further propagation within a narrow valley that changes its orientation several times. the conceptual model of the kinematics is discussed in ostermann et al. (2012) and in tab. 3 we summarize the basic parameters of both rock avalanches. the age of 8.3 ±0.7 ka of the pragser wildsee rock avalanche and the 8.6 ±0.6 ka obernberg rock avalanche may suggest a relation with the “8.2 ka cooling event” (cf. rohling & pälike, 2005), but for more detailed discussion about this potential relationship, refer to ostermann et al. (2012). nevertheless, we underline the importance of strong tectonic events as triggers for holocene rock avalanches (e.g. ambrosi & crosta, 2006; prager et al., 2008) and there are recent (e.g. 2008 wenchuan earthquake, guo et al., 2015) and historic (e.g. 1348 villach earthquake, brandt, 1981) examples for earthquake triggered landslides. 7. conclusions 1 according to the results of surface exposure dating of boulders we think that the pragser wildsee rock avalanche occurred 8300 ±700 years ago; this age is supported by a 14c minimum age of 7410 ±100 a cal bp of organic remnants from a drill core out of the backwater sediments within the pragser wildsee (irmler, 2003). 2 the pragser wildsee rock avalanche is one of the few dated mass-wasting event in the alps that potentially was associated with the 8.2 ka climatic cooling. the precise nature of the 8.2 ka event in the southern alps, however, is insufficiently documented to sustain speculations on a triggering cause of the rock avalanche under a particular climatic condition. 3 the distal 3.5 km of rock-avalanche deposits show an array of transverse ridges and toma hills. these were previously interpreted as moraines and kames. the internal fabric and nature of the sediment of the ridges are, however, incompatible with glacial moraines, but consistent with an origin from a rock avalanche. 4 several factors can be named as predisposing for the rock avalanche at pragser wildsee: the tectonic/ structural framework of a dip-slope layered rigid calcareous sediment succession, dissected by faults and joints, the destabilization in the upper part of the riedl valley due to pronounced facies interlocking and the karstification, especially in the schlern fm. acknowledgements this research was supported by autonome provinz bozen-südtirol provincia autonoma di bolzano alto adige, amt für hochschulförderung, universität und forschung, project: age inventory and analysis of catastrophic rock slope failures in south tyrol. the laboratory of ion beam physics, eth zurich, supported laboratory work, and ams measurements. special thanks goes to the team of the department of geology at the university of innsbruck. we thank monica ghirotti, heike schneider and an anonymous reviewer whose comments/suggestions helped improve and clarify this manuscript. references abele g. 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(2018) erläuterungen zur geologischen karte von italien im maßstab 1:50.000, blatt 016 toblach, pp. 294. guo d., he c., xu c., hamada m., (2015) analysis of the relations between slope failure distribution and seismic ground motion during the 2008 wenchuan earthquake. soil dyn. earthq. eng., 72, 99-107. hantke r. (1983) eiszeitalter: die jüngste erdgeschichte der schweiz und ihrer nachbargebiete.band 3: westliche ostalpen mit ihrem bayerischen vorland bis zum inn-durchbruch und südalpen zwischen dolomiten und mont blanc. 1-730, ott, thun, switzerland. heiss c. (1992) der pragser wildsee. smaragd der dolomiten. verlag la commerciale borgogno, bozen, italy, 1-32. hoek e., bray j.w. (1981) rock slope engineering (revised third edition). institute of mining and metallurgy, london, pp.358 irmler r. (2003) seesedimente als natürliches archiv zur erstellung eines murkalenders am beispiel des pragser wildsees (norditalien). ph.d. thesis, friedrich-schiller-universität jena, germany, 1-96. ivy-ochs s., von poschinger a., synal h.-a., maisch m. (2009) surface exposure dating of the flims landslide, graubünden, switzerland. geomorphology, 103, 104-112. ivy-ochs s., synal h.-a., roth c., schaller m. (2004) initial results from isotope dilution for cl and 36cl measurements at the psi/eth zurich ams facility. nucl. instrum. methods phys. res. b 223-224, 623 -627. keim l. (2008) geologie im gebiet schlern seiser alm: vom tethysmeer zum gebirge. gredleriana, 8, 25-46. klebelsberg r.v. (1927) beiträge zur geologie der südtiroler dolomiten. zeitschrift der deutschen geologischen gesellschaft, 79, 280-354. klebelsberg r.v. (1935) geologie von tirol. borntäger, berlin, germany, pp.187. klebelsberg r.v. (1956) südtiroler geomorphologische studien: das pustertal (rienz-anteil). schlernschriften, 151, 1-218. muttoni g., kent d.v., garzanti e., brack p., abrahamsen n., gaetani m. (2003) early permian pangea „b“ to late permian pangea „a“. earth and planetary science letters, 215, 379-394. ostermann m., sanders d., ivy-ochs s., alfimov v., rockenschaub m., römer a. (2012) early holocene (8.6 ka) rock avalanche deposits, obernberg valley (eastern alps): landform interpretation and kinematics of rapid mass movement. geomorphology, 171, 83-93. 189 characteristics and dating of the rock avalanche at pragser wildsee/lago di braies (dolomites, italy) ms. received: july 10, 2020 revised: august 18, 2020 accepted: september 8, 2020 available online: november 30, 2020 190 amq 32(1) i-iii zanchetta leone.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 32 (1), 2018, i iii francesco paolo bonadonna: a tale of a quaternarist gabriello leone, giovanni zanchetta francesco paolo bonadonna (known to everyone as “antonello”) passed away on november 2017. born in rome in 1934 and graduated in geological science in 1961 at the local university, he dedicated all his life to scientific research and teaching. notably, during the 60s/80s of the last century, he was considered an actual innovator in the application of the geochemical and geochronological techniques to the quaternary geology. he worked in rome until 1968 starting as a stratigrapher, exemplary for those years are his works on the stratigraphy of the lazio region, on a paleoecological and paleoclimatological base, carried on along with his colleague p. ambrosetti (bonadonna, 1968). moreover, he devoted himself to the study of diatoms and varved deposits within the uppsala university. upon his arrival at the university of pisa with the purpose of studying the geochronology of quaternary successions, he establishes himself as an eclectic researcher within the nuclear geology laboratory, an innovative university institute and a melting pot of ideas and scientific minds created and led by ezio tongiorgi. in this framework, he designs and makes operational, along with colleague claudio arias, a laboratory of palaeomagnetic measures (arias et al., 1980, 1984); he also collaborates, along with giulio bigazzi, to the development of distal tephrostratigraphy and tephrochronology, using the fission tracks method (bigazzi & bonadonna, 1988; bigazzi et al., 1996), a methodology used, with great intuition, also for the identification of exploitation areas of obsidian during the neolithic period (bonadonna & bigazzi, 1973). he publish a summary document of the quaternary chronostratigraphy of the italian regions (ambrosetti et al., 1972), and he works on the construction of magnetostratigraphic scales of neogenic and quaternary sediments of the mediterranean basin. throughout his career he is also active in the reconstruction of the relative sea level variations: for many years he is vice-president of the inqua subcommittee for the mediterranean area (bonadonna & campetti, 1987). it is also remarkable his dedication to work alongside archeologists: he was appointed as the geology expert during several archaeological campaigns in the libyan sahara region during the 70s and the 80s, published several articles with geoarchaeology and archaeometric contributions, and was a lecturer for the prehistoric archeology graduate school in pisa from 1968. starting from halfway in the 80s, he began a long scientific partnership with gabriello leone, who was already active in the field of stable isotopes geochemistry, working intensively on the palaeoclimatic and palaeoenvironmental applications of methodologies based on the isotopic composition of oxygen and carbon. he focuses in particular on the continental successions, in the mediterranean and south american areas (bonadonna & leone, 1995; bonadonna et al., 1999), an activity in which, from the late 90s, he receives great contribution from his former student giovanni zanchetta. during all his career he nurtures and disseminates his belief on the importance of a multidisciplinary approach to scientific research, underlining the importance of a continuous large-scale correlation between geological, biological and climatic events, for a better comprehension of the history of the planet, in particular on the last 5 ma of the earth history in the mediterranean area, but also on a global scale (ambrosetti et al., 1972; bonadonna & alberdi, 1987; alberdi & bonadonna, 1989; zanchetta et al., 1995). in his last years of the academic career he dedicated himself to the study of the successions of the lower valdarno and coastal tuscany areas (zanchetta et al., 2004), and of central and southern italy, in order to find, with his multidisciplinary approach, large scale correlations between the events that characterized the area during the last mya. moreover, it is not possible to forget the long lasting contribution of bonadonna to the debate of the quaternary lower boundary he strongly suggested to be placed at ca. 2.5 ma. the national, and part of the international scientific community, relegated him in a marginal posi ii tion. time has proven him right. he lectured university courses at the university of camerino, adis abeba and finally as an associate professor in the university of pisa: for many years he was academic of quaternary geology and paleontology, then of geology for the environmental sciences degree. he also lectured in geology for the cultural heritage degree, teaching even after his retirement. during his teaching tenure he tried to instill his passion and enthusiasm to all the student, young and not-so-young that crowded the so called “green laboratory” of via s. maria in pisa: passion and enthusiasm that were always moderated by his renowned scientific conscientiousness. a man with a strong personality and strict principles; he was not willing to compromise and showed a considerable polemic and ideological vein, he was all the life an irreducible "companion", antonello was a difficult person. he was a person devoid of sentimentality and expression of affection, nevertheless he was all the time a generous person, always close to the people who needed and always ready to help students and colleagues in need. in difficult times he was always a person to talk to. on the other hand, he never asked for help: when he suffered a heart attack at the university, he went alone walking to the nearby hospital without telling anybody! this harsh and hard character often brought him into sharp contrast with the official academic world and clearly limited his university career. however, he was never worried about the consequences of his convictions. a tireless and attentive reader of the scientific literature, no matter how early we arrived at the university he was already on his desk reading a pile of papers; he was always up-to-date and he was curating meticulously the citations. lastly, he was open-minded to all the innovation brought by the development of analytics and informatics, on the other hand he was also reminding us that in our field technology was only an instrument for getting knowledge of the causes and to reconstruct the events that occurred in an interval of time of the history of our planet. his wide and extensive scientific production, leone g. & zanchetta g. antonello bonadonna in the field. the autcrops is the fluvial gravels at the base of the s. romano formation of probable mis 12 age. the definition of this unit was one of his last field activity. more than one hundred and fifty publications, is there to witness the consistency of his objectives, enriched by the vastness of his interests, the curiosity for new techniques and his rigorous approach. this volume has the purpose of recollecting the contributions by some of the people who had known him or that have beneficiated from his work as a well-rounded “quaternarist”, remembering the scientist and the man, a distinction, which sometimes proves to be very difficult for those who live and breathe this beautiful profession. gabriello leone and giovanni zanchetta * *g. leone and g. zanchetta have been, in different times and modality, scholars and partners of “antonello”, to whose figure as a man of science and a colleague, they owe a lot. references adkins j.f., boyle e.a., curry w.b., lutringer a. (2003) stable isotopes in deep-sea corals and a new mechanism for vital effects. geochimica et cosmochimica acta, 67, 1129-1143. alberdi m.t. bonadonna f.p. (editors) (1989) geología y paleontología de la cuenca de guadix-baza., museo nacional de ciencias naturales, csic, madrid, 79-95. ambrosetti p., azzaroli a., bonadonna f.p., follieri m. (1972) a scheme of pleistocene chronology for the tyrrhenian side of central italy. boll. soc. geol. ital., 91, 169-184. ambrosetti p., bonadonna f.p. (1967) revisione dei dati sul plio-pleistocene di roma 1967. atti accademia gioenia di sc. nat. in catania, 18, 33-70. arias c., bigazzi g., bonadonna f., brunnacker k., urgan b. (1984) correlation of plio-pleistocene deposits of the lower rhine basin (north-west germany) and the valle ricca pits (central italy). quat. sc. rev. 3, 73-89 arias c., azzaroli a., bigazzi g., bonadonna f. (1980) magnetostratigraphy and pliocene-pleistocene boundary in italy. quat. res., 13, 65-74. bigazzi g., bonadonna f.p. (1988) fission track dating of a volcanic ash layer near pisticci (basilicata, italy). alpine and mediterranean quaternary, 1, 127-129 bigazzi g., bonadonna f.p., zanchetta g. (1996) farola monte hermoso: fission-track dating of darwin's mammals deposit in argentina. journal of quaternary science 11, 423-426. bonadonna f.p. (1968) studi sul pleistocene del lazio. v. la biostratigrafia di monte mario e la “fauna malacologica mariana” di cerulli-irelli. mem. soc. geol. it, 7, pp. 261-321. bonadonna f.p., campetti s. (1987) annotated bibliography of italian quaternary shorelines (1970-1984): subcommission on mediterranean and black sea shorelines. f.p. bonadonna editor, pacini editore, pisa, 480 pp. bonadonna f.p., alberdi m.t. (1987) equus stenonis cocchi as a biostratigraphical marker in the neogene-quaternary of the western mediterranean basin: consequence on galerian-villafranchian chronostratigraphy. quaternary science reviews, 6 55-66. bonadonna f.p., bigazzi g. (1973) fission track dating of the obsidian of lipari island (italy). nature 242, 322-323. bonadonna f.p., leone g. (1995) palaeoclimatological reconstruction using stable isotope data on continental molluscs from valle di castiglione, roma, italy. the holocene, 5, 461-469. bonadonna f.p., leone g., zanchetta g. (1999) stable isotope analyses on the last 30 ka molluscan fauna from pampa grassland, bonaerense region, argentina. palaeogeography, palaeoclimatology, palaeoecology 153, 289-308. zanchetta g., bonadonna f.p., marcolini f., ciampalini a., fallick a.e., leone g., michelicci l. (2004) intra-tyrrhenian cooling event deduced by a non-marine mollusc assemblage at villa s. giorgio (livorno, italy). bollettino della societa paleontologica italiana, 43, 331-343. zanchetta g., alberdi m.t., bonadonna f.p., leone g. (1995) escenario de la evolución climática entre la región pampeana y el área del mediterráneo occidental durante el cuaternario. in: alberdi m.t., leone g. y tonni e.p. (editores), evolución biológica y climática de la región pampeana durante los últimos 5 millones de años. un ensayo de correlación con el mediterráneo occidental. monografías del museo nacional de ciencias naturales (csic), madrid, 407-423. iii francesco paolo bonadonna: a tale of a quaternarist iv amq abs maceroni et al tepro 221-224.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, abstracts, aiqa 13-14/06/2018 florence, 221 224 application of quaternary studies for the assessment of active and capable faults in the central apennines: implications for microzonation and seismotectonic analyses deborah maceroni 1, simone racano 1, emanuela falcucci 2, stefano gori 2, fabrizio galadini 2 1 università degli studi roma tre, roma, italy 2 ingv istituto nazionale di geofisica e vulcanologia, roma, italy corresponding author: d. maceroni <deb.mac993@gmail.com> abstract: the study of the quaternary evolution of defined areas for the recognition and characterization of active and capable faults is essential for an adequate and aware land use planning and management. here, we present two case studies in the abruzzi apennines, one in the celano area, where focused geological studies allowed us to rule out the presence of an active and capable fault in a site selected for the realization of a primary school, and one in the bagno area, where an active and capable fault has been first detected and should be included in revised seismic microzonation studies. keywords: quaternary, seismic microzonation, active and capable faults, palaeoseismology, central apennines 1. introduction the study of the quaternary geological evolution of tectonically active areas is fundamental to define the recent kinematic history of faults, both for seismotectonic studies and, in urban areas, for planning activities aimed at reducing the risk connected to the fault activity. the central apennine is characterized by a number of normal faults active through the quaternary, which are considered the surface expression of seismogenic sources potentially responsible for m 6.5-7 seismic events. the faults generally bound to the north-east the intermontane basins where cities, villages and urban areas are mostly located. in this work, we present two case studies in the abruzzi region, one in the fucino basin and one in the l’aquila basin, to show the application of quaternary geological studies to active and capable faulting assessment, and their effectiveness in land use planning and management, in particular in terms of planning actions aimed at reducing the related risks. the first case study is located in the town of celano (aq), along the northern margin of the fucino basin, where a complex quaternary normal-fault arrangement is shown by the available literature (e.g. galadini and messina, 2004). the 1st level of seismic microzonation studies performed in the area indicates the presence of an active and capable fault and defines a large setback (according to the linee guida per la gestione del territorio in aree interessate da faglie attive e capaci) which encompasses the area of the “ex campo bonaldi”, that was formerly selected for the realization of a school. the active and capable faults database ithaca reports an active and capable fault in the site of the school (fig. 1), related to the northern portion of the fucino fault system (cavinato et al., 2002; bianchi fasani et al., 2008). the second case study is in the area of bagno (aq), in the l’aquila basins. here, nocentini et al. (2017) hypothesised the presence of a normal fault in the area, that is not reported in the 1st level seismic microzonation studies performed in the area after the 2009 l’aquila earthquake. 2. materials and methods a multidisciplinary approach is applied to the identification of active and capable faults in the two case studies. in particular, we carried out geological surveys and aerial photo interpretation aimed at defining the quaternary morpho-stratigraphic setting useful to cast light on the recent fault activity. in both case studies, we performed palaeoseismological investigations to unravel the possible presence of active and capable faults and, if any, to investigate their recent activity. as for the celano area, we also performed two boreholes with the goal of achieving more robust chrono-stratigraphic data in the site of the school. 3. results 3.1. celano the trench at the “ex campo bonaldi” site (fig. 2) exposed five continental units which were not affected by any fault plane. the absence of dislocation is also confirmed by the horizontal stratigraphic continuity of the sequence cored by the boreholes we made at the extremities of the trench. the geological field survey of the quaternary units we made in the area of celano gave evidence of late quaternary activity of nw-se trending faults, comprising the santa iona normal fault, which displaced eluvial deposits deriving from deposits of the second sedimentary https://doi.org/10.26382/aiqua.2018.aiquaconference fucino cycle (bosi et al, 2003), related to the early pleistocene. differently, n-s trending normal faults that affect the western slope of the serra di celano relief are clearly sealed by early pleistocene breccias, thus testifying inactivity of these structures in recent times. 3.2. bagno the geological-geomorphological survey in the area of bagno piccolo revealed the presence of a scarp oriented nw-se and dipping toward ne. an excavation for a building made along the scarp (fig. 3a) allowed us to first reveal the presence of a normal shear zone which 222 fig. 1 red lines show active and capable faults from database ithaca in the town of celano. maceroni d., et al. fig. 2. stratigraphy of eastern wall of the palaeosismological trench. five continental units have been recognized: colluvial deposits (brown and yellow), paleosol (blue) and alluvial deposits (pink and violet). 223 brought into contact miocene flysch and quaternary deposits (alluvial fan and colluvial sediments) (fig. 3b). following nocentini et al. (2017), the alluvial fan deposits can be related to the “sintema di campo di pile”, dated to the late pleistocene. this indicates a late quaternary activity of the fault. further analyses are still ongoing to better characterise the recent movements of this fault zone. 4. discussion and conclusions the field geological survey and the analysis of trenches allowed to verify or exclude the presence of faults in the investigated sites and to achieve a better definition of the quaternary activity of the identified faults. in the case of celano, we didn’t find any evidence of active faulting in the area of the “ex campo bonaldi”, where the ithaca database suggests the presence of fig. 3 example of cave dug into the tuff. a) view of a chamber with an access well on top; b) details of access realized with steps directly carved into the tuff. active faults studies for land use management fig. 3 a) bagno piccolo locality crossed by a scarp, marked by the red dashed line. b) normal fault zone (red line) that placed into contact miocene flysch with continental deposits. an active and capable fault. we found evidence of late quaternary activity in the area of celano along nw-se trending faults (especially along the santa iona fault), which confirms the probable structural linkage between the “strada statale marsicana” segment of the active fucino fault and the monti della magnola segment (galadini et al, 1998; galli et al, 2012). moreover, the absence of late quaternary activity along the n-s trending normal faults located along the western slope of the serra di celano relief highlights the probable lack of structural linkage between the fucino and ovindolipezza fault systems. regarding the bagno piccolo case study, the first identification of a probable active and capable normal fault provides new important information on active faults affecting the l’aquila area and new detailed data for the seismic microzonation in the area struck by the 2009 earthquake. references bianchi fasani g., cavinato g.p., petitta m., scarascia mugnozza g., voltaggio m. (2008) the geological model of celano town area for seismic microzonation activities. soil dynamics and earthquake engineering, 28, 978-985. bosi c., galadini f., giaccio b., messina p., sposato a. (2003) plio-quaternary continental deposits in the latium abruzzi apennines: the correlation of geological events across different intermontane basins. il quaternario,16(1bis), 55-76. cavinato g. p., carusi c., dall’asta m., miccadei e., piacentini t., (2002) sedimentary and tectonic evolution of plio-pleistocene alluvial and lacustrine deposits of fucino basin (central italy). sedimentary geology, 148, 29-59. galadini f., messina p. (2004) early-middle pleistocene eastward migration of the abruzzi apennine (central italy) extensional domain. journal of geodynamics., 37, 57-81 galadini f., galli p., molin d. (1998) caratteristiche della sismicità della zona del fucino (italia centrale): implicazioni sismotettoniche. il quaternario, 11 (2), 1998, 179 189. galli p., messina p., giaccio b., peronace e., quadrio b. (2012) early pleistocene to late holocene activity of the magnola fault (fucino fault system, central italy). bollettino di geofisica teorica ed applicata 53(4), 435-458. nocentini m., asti r., cosentino d., durante f., gliozzi e., macerola l., tallini m. (2017) plio quaternary geology of l’aquila scoppito basin (central italy). journal of maps, 13(2), 563-574. catalogo italy hazard from capable faults (ithaca) of the istituto superiore per la protezione e la ricerca ambientale (ispra) (http://www.sgi. isprambiente.it/geoportal/catalog/progect/ithaca.page) (last check of availability may 2018). commissione tecnica per la microzonazione sismica (2015) linee guida per la gestione del territorio in aree interessate da faglie attive e capaci (fac), versione 1.0 conferenza delle regioni e delle provincie autonome-dipartimento della protezione civile, roma, 2015. ms. received: may 6, 2018 final text received: may 24, 2018 224 maceroni d., et al. sess 1_160211.pub il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 sea level changes and vertical movements of the land in the mediterranean region from integrated data marco anzidei1, 2, fabrizio antonioli3, kurt lambeck4, dorit sivan5, mohamed soussi6, enrico serpelloni7, silvia pondrelli7, gianfranco vannucci7, paolo baldi8, rita auriemma9, alessandra benini10 & emanuela solinas11 (1) istituto nazionale di geofisica e vulcanologia, rome, italy (2)università della calabria, dipartimento di fisica, cosenza, italy (3) enea, casaccia, rome, italy (4) research school of earth sciences, the australian national university, canberra 0200, australia (5) university of el manar, faculty of sciences of tunis, department of geology, tunisia (6) university of el manar, faculty of sciences of tunis, department of geology, tunisia (7) istituto nazionale di geofisica e vulcanologia,bologna, italy (8) università di bologna, dipartimento di fisica, bologna, italy (9) dipartimento beni culturali, universita` degli studi di lecce, lecce, italy (10) università della calabria, dipartimento di archeologia e storia delle arti, cosenza, italy (11) civico museo archeologico sa domu nosta, cagliari, italy corresponding author: m. anzidei <marco.anzidei@ingv.it> abstract: anzidei m. et al., sea level changes and vertical movements of the land in the mediterranean region from integrated data. (it issn 0394-3356, 2011) riassunto: anzidei m. et al., variazioni del livello marino e movimenti verticali della terra nell’area mediterranea da dati integrati. (it issn 0394-3356, 2011) key words: mediterranean, sea level, archeology, geodesy, geophysics parole chiave: mediterraneo, livello del mare, archeologia, geodesia, geofisica coastal settlements and maritime installations built in antiquity provide important insights into sea-level changes during past millennia, and reconstructions of historical sea-level change using archaeological coastal sites are particularly effective in the mediterranean sea, whose coastlines still preserve remnants of human activity since the last glacial maximum. the first pioneering results on sea level changes from archaeological indicators in the mediterranean were published during the ‘70s (flemming, 1969; caputo & pieri, 1976; schmiedt, 1974; pirazzoli, 1976; flemming & webb, 1986), but new and more detailed results arise for the mediterranean during the last decade (antonioli et al., 2007; lambeck et al., 2010a & references therein; lambeck et al., 2010b; anzidei et al., 2010a; anzidei et al., 2010b;). unfortunately, despite the large number of archaeological remains in the mediterranean, only a part of them can be used to obtain reliable information on their former relationship to sea level (auriemma & solinas, 2009). limitations arise as a result of their uncertain use, poor preservation, or because they were built in geologically unstable areas which produce local disturbances. although the oldest known archaeological site useful to constraints the sea-level change in the mediterranean (lambeck & purcell, 2005) starts with the 22 ka flooded paintings of cosquer cave (southern france) today 37 m below sea level (clottes et al., 1997), particularly valuable are the roman age coastal sites. fish tanks, piers and harbors constructions, generally dated between the 1st century bc and the 1st century ad, are very precise indicators (lambeck et al., 2004b). quarries carved along the coastlines and located nearby fish tanks and harbors or villas of similar age, can provide additional data on past water level, as well as information on their elevation above sea level, although these alone are less precise indicators. we provide a data base of coastal archaeological sites with valid records dated back to 1.6-2.5 ka bp, using direct observations as well as archaeological, geophysical and geological literature. particular attention was given to the elevation of the significant architectural features related with the sea level. these include the system of channels of the fish tanks, bollard and piers for harbors, lower cuttings for quarries, bottom end of slipways. in addition to those artifacts which provide precise data, other features can be classified as to whether they must have been dry (house pavements, roads, tombs), 14 16 15 partially in the water (piers, quays, moles, slipways, fish tanks), or completely submerged (floor of channels for water exchange in the fish tanks, floor of fish tanks, channels at the entrance of harbors, floor of harbors). when different class of structures exist at a single site, as for example at ventotene island (italy), we can obtain a very accurate estimation of the relative sea level change as well as understand the relationships between their elevations with respect to the mean sea level at the time of their construction. moreover, structures from different ages can provide a relative sea level curve for that specific site. to obtain precise measurements of the relative sea level change at the archaeological sites, we defined the “functional elevation” as the elevation of specific architectural parts of an archaeological structure with respect to the local mean sea level at that location and at the time of its construction. it depends on the type of structure, its use and the local tide amplitudes. the minimum elevation of particular structures above the local highest tides can also be defined. field data from more than 150 sites of valid archaeological markers were used in our study. field measurements were performed by invar rod, optical or electronic methods, during calm sea with null wave action. elevations are related to the sealevel position at that moment. data accuracy with their uncertainties for age and elevation at each site, are estimated on the basis of the type of indicator used and of the historical literature, based on the artifacts or on the architectural features. observations of geomorphological indicators, such as beachrocks and solution notches, are used to integrate and reinforce the archaeological interpretations as in antonioli et al. (2007). the use of these structures, their age and conservation, the accuracy of the survey and the estimation of the functional heights were all used in considering the observational uncertainties at each site. accuracy of the elevations of the data set is within 0.5-0.2 m, although some limitations occurs, as for quarries or slipways, which are less precise indicators in comparison with fish tanks (lambeck et al., 2004b). the analysis was performed during four different steps: 1) the elevation of the valid sites were measured (average value of multiple measurements of the best preserved parts of the investigated structures) with respect to the sea level at the time of surveys; 2) measurements were reduced to mean sea level of the site itself, applying tidal corrections at the surveyed sites, using the data of the nearby tide gauges (www.idromare.it; www.psmsl.ac.uk). in the cases of the unavailability of tide gauge data were we used the predicted tide estimation, corrected for local pressure values. we estimate errors for the elevations and ages of the archaeological markers and evaluate their functional elevations on the basis of archaeological interpretations. since the investigated archaeological structures were originally used year round, we assume that the defining levels correspond to the annual mean conditions at the time of construction. age errors are estimated from the architectural features and historical documents, while elevation errors derive from the measurements of the functional heights (for example, the lower limiting values for the quarries and slipways); 4) finally, we examined the predicted and observed sea levels, by comparing the current elevations of the markers (i.e. the relative sea-level change at each location) with the sea-level elevation predicted by the proposed glacio-hydro-isostatic model for each location. we hypothesize tectonic stability at the sites where the elevations of the markers are in agreement with the predicted sea-level curve. conversely, we hypothesize that the area has experienced tectonic or volcanic subsidence or uplift when the elevations of the markers are below or above that of the predicted sea-level curve, respectively. the archaeological evidences is providing a new picture of the spatial distribution of the sea level changes in mediterranean since the last ~2.3 ka. despite the limitations and resolution of the available data with respect to the known tectonic complexity of the study region, an integrated use of historical data, geological observations of the elevation of mis 5.5, instrumental data of tide gauges and vertical gps can provide, together with an accurate modelling of the glacio-hydroisostatic contribution for vertical land movements and amount of water in the basin, to a more comprehensive description of the causes that are driving the sea level change since ~2.5 ka and their current rates at different locations, as reported in ferranti et al., 2010. we use the calibrated model results to separate out the tectonic contribution, widely diffused in the mediterranean, from the vertical movements related to the glacio–hydro-isostatic changes. our analysis are consistent with model predictions as well as trends inferred from seismic strain analysis of earthquakes occurred during the last 30-40 years and tide gauge data for the last ~100 yr. this indicates that besides the glacio–hydro-isostatic effect, also the tectonic contribution can affects the relative sea level changes along the coastlines of the mediterranean, since the last ~2.5 ka. sea level changes and vertical movements of the land ... 16 ms. received: testo ricevuto il references antonioli f., anzidei, m. auriemma, r., gaddi d., furlani s., lambeck k., orrù p., solinas e., gaspari a., karinja s.,kovačić v. & surace l. (2007) sea level change during holocene from sardinia and northeastern adriatic (central mediterranean sea) from archaeological and geomorphological data. quat. sc. rev., 26, 2463 –2486. anzidei m., antonioli f., benini a., lambeck k., sivan d., serpelloni e. & stocchi p. (2010) sea level change and vertical land movements since the last two millennia along the coasts of southwestern turkey and israel. quat. int., 10.1016/j.quaint.2010.05.005 anzidei m., antonioli f., lambeck k., benini a., soussi m. & lakhdar r. (2010) new insights on the relative sea level change during holocene along the coasts of tunisia and western libya from archaeological and geomorphological markers. doi:10.1016/j.quaint.2010.03.018. auriemma r. & solinas e. (2009) archaeological remains as sea level change markers: a review. quat. int. 206, 134-146. caputo m. & pieri l.(1976) eustatic variation in the last 2000 years in the mediterranean. j. geophys.res. 81, 5787– 5790. clottes j., courtin j., collina-girard j., arnold m. & valladas h. (1997) news from cosquer cave: climatic studies recording, sampling, dates. antiquity 71, 321-326. ferranti l., fabrizio a., anzidei m., monaco c. & stocchi p. (2010) the timescale and spatial extent of vertical tectonic motions in italy: insights from relative sea-level changes studies. http:// virtualexplorer.com.au/article/2009/255/verticaltectonic-motions-in-italy flemming n.c. (1969) archaeological evidence for eustatic changes of sea level and earth movements in the western mediterranean in the last 2000 years. geol. soc. am., sp. paper 109. flemming n.c. & webb c.o.(1986) tectonic and eustatic coastal changes during the last 10,000 years derived from archaeological data. z. geomorphol. n.f., 62, 1 –29. lambeck k., anzidei m., antonioli f., benini a. & esposito e. (2004b) sea level in roman time in the central mediterranean and implications for modern sea level rise. earth planet. sc. lett., 224, 563-575. lambeck k. & purcell a. (2005) sea-level change in the mediterranean sea since the lgm: model predictions for tectonically stable areas. quat. sc. rev. 24, 1969–1988. lambeck k., woodroffe c.d., anzidei m., antonioli f., gehrels w.r., van de plassche o. & wright a.j. (2010) palaeoenvironmental r e c o r d s , g e o p h y s i c a l m o d e l l i n g a n d reconstruction of sea-level trends and variability on centennial and longer time scales. in church j.a., woodworth p.l., aarup t., wilson w.s. eds. “understanding sea-level rise and variability”. blackwell publishing, london. lambeck k., antonioli f., anzidei m., ferranti l., leoni g., scicchitano g. & silenzi s. (2010). sea level change along the italian coast during the holocene and projections for the future. quat. int. doi:10.1016/j.quaint.2010.04.026 pirazzoli p.a. (1976) sea level variations in the northwest mediterranean during roman times. science 194, 519– 521. schmiedt g. (1974) il livello antico del mar tirreno. testimonianze da resti archeologici. e. olschki eds., firenze, 323 pp. m. anzidei et al. january 14, 2011 14 gennaio 2011 sess 1_160211.pub il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 persististrombus latus-bearing deposits south of isola di capo rizzuto, calabria (southern italy) valentina alice bracchi 1, ronald nalin 2 & daniela basso 1 1 university of milano-bicocca, italy 2 geoscience research institute, ca, usa corresponding author: v.a. bracchi <v.bracchi@campus.unimib.it> abstract: bracchi v.a., nalin r. & basso d., persististrombus latus-bearing deposits south of isola di capo rizzuto, calabria (southern italy). (it issn 0349-3356, 2011) during a research fieldtrip in the crotone peninsula an area characterized by a flight of well developed pleistocene marine terraces a level rich of in situ persististrombus latus gmelin 1791 (= strombus bubonius lamarck 1822) has been discovered in a quarry south of isola di capo rizzuto (calabria, southern italy) at ~ 46 m above sea level. p. latus is a shallow warm-water marine gastropod belonging to the strombidae family. presently, it lives along the tropical coasts of africa but entered the mediterranean through the gibraltar strait in the late pleistocene as part of the socalled senegalese fauna. p. latus found as fossil in the mediterranean is commonly considered a marker of marine isotope stage (mis) 5.5. this is the first documented record of a level containing multiple specimens of in situ p. latus in the crotone terraces, allowing direct correlation to the tyrrhenian stage or mis 5.5. the bio-calcarenite and associated p. latus specimens have been collected in order to petrographically analyze the sediment and describe the benthic association. riassunto: bracchi v.a., nalin r. & basso d., persististrombus latus in depositi di terrazzo marino a sud di isola di capo rizzuto, calabria (italia). (it issn 0349-3356, 2011) durante una campagna di ricerca nella penisola di crotone, area caratterizzata dalla presenza di terrazzi marini ben sviluppati, è stato rinvenuto un livello ricco di persististrombus latus gmelin 1791(= strombus bubonius lamarck 1822) in situ, in una cava posta a sud di isola di capo rizzuto (calabria, italia) a circa 46 m di altitudine. p. latus è un gasteropode di acque calde e poco profonde della famiglia strombidae. e’ tuttora vivente lungo le coste tropicali africane, ma si introdusse nel mar mediterraneo attraverso lo stretto di gibilterra nel tardo pleistocene, come membro della fauna detta senegalese. p. latus viene comunemente considerato un marker dello stadio isotopico marino (mis) 5.5. questo è il primo ritrovamento documentato di un livello contenente molteplici esemplari in situ di p. latus nell’area dei terrazzi crotonesi, permettendo una correlazione diretta con lo stadio tirreniano o mis 5.5. la bio-calcarenite associata ed esemplari di p. latus sono stati campionati al fine di analizzare petrograficamente il sedimento e descrivere l’associazione bentica. keywords: persististrombus latus, pleistocene, tyrrhenian stage, mis 5.5, calabria, crotone peninsula parole chiave: persististrombus latus, pleistocene, tirreniano, mis 5.5, calabria, penisola di crotone. during a fieldtrip in the crotone peninsula, aimed at the study of the biogenic deposits of the le castella and capo colonna marine terraces, multiple specimens of persististrombus latus gmelin 1791 (= strombus bubonius lamarck 1822) were discovered in a quarry located south of isola di capo rizzuto (calabria, italy). p. latus is a shallow warm-water marine mollusc of the strombidae family, presently living exclusively on the tropical coasts of africa. however, p. latus is commonly found as fossil in late pleistocene deposits of the mediterranean region, being a representative of the so-called ‘senegalese’ fauna which entered the mediterranean through the gibraltar strait in the mid-late pleistocene (gignoux, 1913; issel, 1914; selli, 1962; ruggieri et al., 1968; issar a., 1969; bonfiglio, 1972; 1981; di grande & scamarda, 1973; herm et al., 1975; fleisch et al., 1981; porta & martinell, 1981; cataliotti valdina, 1984; bossio et al., 1986; hearty & dai pra, 1986; caldara, 1987; flores et al., 1987; gliozzi, 1987; spanò, 1991; 1993; causs et al., 1993; lario et al., 1993; sivan et al., 1994; kéraudren et al., 2000; jedoui et al., 2003; zazo et al., 2003; federici & pappalardo, 2006). p. latus has historically become a characteristic marker of mis 5.5 and the tyrrhenian (the last faunal stage of the pleistocene in mediterranean area) (gignoux, 1913; issel 1914; cita & castradori, 1995) and is commonly used to correlate and chronologically constrain deposits of raised beaches (e.g. hearty, 1986; ferranti et al., 2006). the crotone peninsula is characterized by the presence of well developed pleistocene marine terraces, generated by the interplay of sea-level change and progressive uplift of the calabrian arc. these terraces were first reported by cortese (1895) and were subsequently studied by several authors from a geomorphic, stratigraphic, 23 25 24 sedimentologic, paleontologic and geochronologic point of view (gignoux, 1913; ruggieri 1948; 1951; selli, 1962; gueremy, 1972; belluomini et al., 1987; gliozzi, 1987; cosentino et al., 1989; palmentola et al., 1990; mauz & hassler, 2000; zecchin et al., 2004; 2010; nalin et al., 2006; 2007; nalin & massari, 2009). selli (1962) was the first to report the occurrence of p. latus in one of the terraces, at an elevation between 45 and 55 m above sea level (asl), but did not provide details of the finding. gliozzi (1987) reported the occurrence of very rare p. latus specimens on dislocated blocks from the area of campolongo, north of le castella village, 80 m asl, and identified a unique s. leonardo di cutro-campolongo-isola di capo rizzuto terrace correlated to mis 5.5. palmentola et al. (1990) located patches of a marine terrace between capo cimiti (15 m asl) and la mazzotta (84 m asl) with a typical warm water fauna correlated to mis 5.5, but found only one specimen of p. latus in this terrace on a dislocated block. in recent restoration works of the aragonese castle of le castella, a block of calcarenite containing numerous p. latus specimens was included in the stone pavement of the platform that protects the southern portion of the castle from wave washout. reasoning that the block should have been extracted from a nearby quarry, a careful search of recently active quarries led to the finding of a level preserving several in situ p. latus specimens (5 specimens in a surface exposure area of ~ 2 m2) and other five specimens in piled blocks extracted from the quarry deposits. the quarry is located south of the isola di capo rizzuto village, in a morphological terrace (between 41 and 57 m asl) that is part of the s. leonardo-campolongo-isola di capo rizzuto terrace of gliozzi (1987). (gps position of the surface with in situ p. latus: n38 56.566 e17 04.444; approximate elevation: 46 m asl). the p. latus specimens are sparsely distributed on the exposed surface, and are larger than 5 cm in size. they are contained in a monotonous succession of cross-stratified medium to coarse calcarenite, showing gentle clinostratification towards the south. other bioclasts include large disarticulated bivalve valves (most likely glycimeris sp.) this level is the first documented occurrence of in situ multiple specimens of p. latus in the area of isola di capo rizzuto and allows correlating these outcrops with mis 5.5. the recorded elevation is concordant with selli (1962) and intermediate with respect to the other reports on dislocated blocks (gliozzi, 1987; palmentola et al., 1990). the latter discrepancy could be ascribed to the patchy and tectonically disturbed distribution of the mis 5.5 deposits in the crotone peninsula area (gliozzi, 1987; cosentino et al., 1989; zecchin et al., 2004). references belluomini g., gliozzi e., ruggieri g., branca m. & delitala l. 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(2010) anatomy of a late pleistocene clinoformal sedimentary body (le castella, calabria, southern italy); a case of prograding spit system? sed. geol., 223, 291-309. persististrombus latus-bearing deposits south ... january 14, 2011 14 gennaio 2011 amq107 baneschi et al.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 33 (1), 2020, 99-106 are stable isotopes of lacustrine carbonate a good tracer of lake hydrology and lake level variability? the lake ledro case (northern italy). ilaria baneschi 1, michel magny 2, giovanni zanchetta 3, 4, 5 1 istituto di geoscienze e georisorse igg-cnr, pisa, italy. 2 laboratoire de chrono-environnement, umr 6249 du cnrs, ufr des sciences et techniques, besançon, france. 3 dipartimento di scienze della terra, university of pisa, pisa, italy. 4 centre for climatic change impact cirsec, university of pisa, pisa, italy. 5 istituto di geologia ambientale e geoingegneria, igag-cnr, rome, italy. corresponding author: i. baneschi <i.baneschi@igg.cnr.it> abstract: oxygen and carbon isotopes were analysed on bulk samples and carbonate concretions from lake ledro, northern italy, with the aim to assess their suitability as reliable proxy of the hydrological changes in the lake. for this purpose, isotopic composition of bulk marls and concretions were compared to lake level reconstruction obtained with sedimentological approach. the δ13cbulk record mostly mirrors the δ 18obulk record, while carbon and oxygen isotopes from concretions are not correlated. we found that there is a statistically significant correlation between the oxygen and carbon isotopic record of the bulk carbonate and lake level changes, with the positive changes in lake level corresponding to lower values on δ18obulk and δ 13cbulk and vice versa. assuming that most of the bulk carbonate is formed by bio-induced calcite precipitation, this means that this kind of carbonate reflects the local hydrological condition of the lake water better than lacustrine concretions, which instead are more affected by local conditions of precipitation like biological plant activity. keywords: stable isotopes carbonate; lacustrine carbonates; lake level; lake ledro. 1. introduction the hydrological balance of lakes may respond sensitively to changes in net precipitation and humidity, which often are accompanied by change in the lake level. hence, the lake level is a sensitive proxy that document past changes in lake water budget, and past climate (e.g., magny, 2013 and reference therein). in lacustrine settings, stable isotopes of carbonates are a frequently used as proxy to identify and reconstruct terrestrial environmental changes and have been extensively used in quaternary paleoenvironmental reconstructions (e.g., eicher & siegenthaler, 1976; punning et al., 1984; lotter et al., 1992; mayer and schwark, 1999; zanchetta et al., 1999; schwander et al., 2000; hammarlung et al., 2003; andresson et al., 2010; jonsson et al., 2010; whittington et al., 2015). the oxygen isotopic composition of inorganic lake carbonate is mainly influenced by: (1) the oxygen isotope composition of precipitation in the watershed, (2) the water temperature at time of carbonate precipitation, and (3) the hydrological balance of the lake (buchardt & fritz, 1980; gibson et al., 1993; von grafenstein et al., 2000; ito, 2001; leng & marshall, 2004; bernasconi & mckenzie, 2007). in specific conditions, the hydrological balance dominates the oxygen isotopic signal of water lakes and, consequently, that of inorganic carbonates (roberts et al., 2008). so it should be related to changes in lake level. despite this argumentation is commonly used as rational for interpreting the isotope signal as proxy of the lake level change (e.g., leng et al., 2010), there are very few examples of direct comparison between lake level records and oxygen isotope composition of lake carbonate. a comparison between bulk lacustrine carbonate stable isotopes and changes in lake level reconstructed using sedimentological approach (magny, 1992, 1998) have been performed for instance on the study of gerzensee lake, on the swiss plateau at 603 m a.s.l., and lautrey lake, located at 788 m a.s.l. in the jura mountains (eastern france) (magny, 2001, 2013; magny et al., 2006). when using the carbon and oxygen isotopes for lake level reconstruction, many complex factors have to be carefully taken into account. usually, the interpretation of the 13c/12c ratio in lacustrine carbonate is more complex than that of 18o/16o ratio. variations of δ13c values of precipitated calcite in general reflect the δ13c values of the dissolved inorganic carbon (dic), which is controlled by the isotopic composition of incoming waters, the exchange of co2 between lake surface waters and the atmosphere, by photosynthesis and respiration of algae and aquatic macrophytes, and by organic mat https://doi.org/10.26382/amq.2020.09 100 baneschi i. et al. ter decomposition (mckenzie, 1985; lee et al., 1987; meyers & teranes, 2001; teranes & bernasconi, 2005) as well as by carbonate dissolution in the water column. moreover, the input and the isotopic composition of the dic from the catchment depends on several factors such as leaching of soil co2 and dissolution of old carbonates (leng & marshall, 2004; zanchetta et al., 2018). several types of lacustrine carbonates can be studied, like bio-induced carbonates (the most common, sometime called authigenic carbonates; eicher & siegenthaler, 1976; hammarlund et al., 1999, 2003), freshwater shells (e.g. bottger et al., 1998; zanchetta et al., 1999; bonadonna et al., 1999; jones et al., 2002), ostracods (e.g. von grafenstein et al., 1994, 1999; lézine et al., 2010) and chara encrustations (apolinarska & hammarlund, 2009). however, each different type of carbonate forms in specific conditions and, therefore, may give a different type of information (leng & marshall, 2004). in this work, we further explore the relation between oxygen and carbon isotopes and lake level changes using data on bulk carbonates (mainly bioinduced) and lake concretions in cores recovered in lake ledro within a holocene succession, for which chronology and lake level reconstruction has already been performed (magny et al., 2009). 2. site description lake ledro is located at 652 m a.s.l. on the southern slope of the alps (n-e italy, fig. 1), with a surface area of ca. 2.17 km2, a maximum water depth of 48 m, a mean depth of 35 m, and a volume of ca. 0.75 km3. the catchment area is ca. 131 km2 and is developed on a substratum mainly composed by carbonate rock, including triassic (dolomite) and jurassic-cretaceous limestones covered by quaternary glacial deposits. the outlet of the lake is ponale river, which is responsible for the downcutting of the local morainic dam (beug, 1964) and hydrologically links lake ledro to the lake garda (fig. 1). since 1929, the lake level has been artificially regulated for hydroelectric power supply, modifying consequently the natural hydrological variability. lake ledro is fed by many submerged springs and by some minor temporary torrential tributaries: ponale massangla, assat di cencei and sat di pur, which are dry for most of the year. fig. 1 location of lake ledro catchment with an outline map showing the study site in northern italy. the circle marks the core site (core ledro ii). the thick black line indicates the sub-catchment of the different inlet rivers. 101 stable isotopes of carbonate as tracers of lake hydrology the climate of ledro valley is influenced by the near garda lake (65 m a.s.l.), characterized by particularly mild climatic conditions. the mean temperature, recorded at bezzecca weather station (710 m a.s.l.), is ca. 0 °c in the coldest month (january) and ca. 19 °c in the warmest month (july). the mean annual precipitation is ca. 1220 mm, with seasonal maxima in spring and autumn. lake ledro waters can be classified as ca-bicarbonate and are stratified during summer period (corradini & flain, 2000). the yearly mean isotopic composition of precipitations collected from five stations from 1992 to 2001 around the garda area and reported by longinelli & selmo (2003) is -7.47 ±0.91 ‰ for δ18o and -49.3 ±7.3 ‰ for δ 2h. the weighed mean isotopic values of precipitations measured at riva del garda from february 2007 to january 2008 (longinelli et al., 2008) is -7.25 ±0.70 ‰ for δ 18o and -52.1 ±5.9 ‰ for δ2h. 3. materials and methods the present study was carried out on the core retrieved in april 2005 at the site ledro ii, located on the north-eastern shore of the lake (fig. 1). here, a ~ 3 m long core was collected by means of a russian peat corer (magny et al., 2009). the sedimentary succession, under the superficial peat layer, shows an alternation of carbonate lake-marl and organic-rich layers. detailed core description, chronology, pollen and lake-level reconstructions are extensively discussed by magny et al. (2009, 2012), to which the readers are referred for any details. the recovered sediments, dated by means of radiocarbon, represent ca. the last 7000 yr bp. the carbonate lake-marl samples and carbonate concretions were sampled for oxygen and carbon isotopes on bulk carbonate about every 3-4 cm. sediments were sieved at 200 μm. the term “bulk carbonate” is here used for the fine-grained inorganic lake marl (less than 200 μm), mostly devoid of shell and ostracods remains. the carbonate concretions where hand-picked under a binocular microscope from the coarser fraction (larger than 200 μm). this latter material corresponds to the original material selected by magny et al. (2009) for defining lake level oscillations based on different typology of lacustrine concretions (magny, 2004). concretions were cleaned ultrasonically with distilled water to separate adhering particles. the sediment samples were dried at 40°c, powdered and analysed for isotopic composition with no further pre-treatment considering the high carbonate content (manella et al., 2020). all the carbonate samples were reacted with 100% phosphoric acid at 70 °c for 1 h under vacuum to release co2. the released co2 was then cryogenicallycleaned in a vacuum line and analysed in the mass spectrometry varian mat 252. the results were expressed with the well-known δ-notation and normalized to the vienna pee dee belemnite scale (pdb in per mil) using internal working standards of carbonatems, mab (carrara marble) and mom, which were cross-checked against the international standard nbs18. the precision (as standard deviation) of the analyses was better than 0.2‰ for δ13c and 0.2‰ for δ18o. 4. results figure 2 shows isotopic composition of the bulk and carbonate concretions, compared to lake level data vs depth. the δ18o values of bulk sediment (δ18obulk) vary in a range of ca. 1.6 ‰ from ca -10.4 to -8.8 ‰, very similar to the range (ca. 1.7‰) of δ18o values of concretions (δ18oconcr) but the maximum and minimum δ 18oconcr values are lesser negative, ranging between 9.7 and -8.0 ‰. indeed, considering each couple of δ 18obulk and δ 18oconcr at the same depth, the δ 18oconcr has higher oxygen isotope composition than δ18obulk. this means that the difference between δ18oconcr and δ 18obulk is usually positive (fig. 2) with a mean value of 0.8 ‰ and a range from 1.9 to -0.1‰. the δ13c values of bulk sediment (δ13cbulk) fluctu fig. 2 stable carbon and oxygen isotope records of different carbonate components, together with lake level changes, plotted against core depth. ate in a wider range of ca. 3 ‰, i.e., from ca. -2.9 to -5.9 ‰ (fig. 2). the carbon isotopes of concretions are offset from the corresponding values of bulk carbonate of 0.8 ‰ on average with a range from -2.5 to +0.5 ‰. the δ18obulk record is characterized by a relatively low variability from the bottom to around 190 cm, from which frequent and short fluctuations start and minimum δ 18o values are reached at around 173 cm, 147-144 cm, 118-104 cm, 89 cm, 55 cm, 47 and 22 cm. the δ18o of concretions shows similar fluctuations toward more negative values at 173 cm, 144 cm and 104 cm, even if in general there is not a statistically significant correlation between the two records (r=0.22, n=32). the δ13cbulk record mostly mirrors the δ 18obulk one with a good correlation (r=0.59, n=67), in contrast to the carbon and oxygen values of concretions that are not significantly correlated (fig. 3). this is probably related to the presence of different kind of concretions, but also to the different, local, nature of the environment where lacustrine concretions forms compared to bio-induced carbonates. the δ13cbulk values are generally 13c-depleted from the bottom of the record to 230 cm, when the values start to increase reaching the maximum of -3.8 ‰ at around 200 cm. it has to be noted that from 250 to 175 cm there are not samples of concretions analysed because there was not sufficient material, in accord by the fact that the core from 240 to 190 cm is characterized by peat and gyttja and that from 230 cm to 190 cm there are only organic remains without concretions (magny et al., 2009). from 200 cm to the top of the record, δ13cbulk is characterized by frequent fluctuations with the lowest and highest values corresponding to the lowest and highest values on the oxygen record of bulk carbonates, respectively. 5. discussion δ 18o of inorganic carbonates in small/medium open lakes, like lake ledro, dominantly reflects the δ18o of the water during calcite precipitation (ito, 2001; leng & marshall, 2004; teranes et al., 1999). authigenic calcite inorganically precipitates in late spring/early summer in the epilimnion because of changes in lake water chemistry (increased temperature, algal activity and ph changes). however, inorganic carbonates may also be formed as an extra-cellular by-product during photosynthesis. for example, characeae and other microand macrophytes actively remove bicarbonate from the lake system, leading to the formation of inorganic calcite, which typically encrusts the plants (von grafenstein et al., 102 baneschi i. et al. fig. 3 δ18o versus δ13c diagram for the core record of both bulk and concretions. fig. 4 stable carbon and oxygen isotope records of different carbonate components plotted against lake level changes. (bini et al., 2019). overall, we can then assume that higher δ18o values of carbonates correspond to drier period, in which lake level also decreases. considering the lake level reconstructed by magny et al. (2009) from ledro core, the data showed in figure 2 highlight that there is a good correspondence between the oxygen and carbon record of the bulk carbonate, with the positive changes in lake level corresponding to lower values on δ18obulk and δ 13cbulk and, vice versa, with negative changes in lake level corresponding to higher values on δ18obulk and δ 13cbulk. this behaviour is evident also for the carbon record of concretions, with higher δ13cconcr values corresponding to lower level lake, whereas δ18oconcr shows in some case opposite trends compared to lake level. in fact, considering all the record there is a statistically significant (at 0.05 significance level) negative correlation between the lake level changes with the δ18obulk (r=-0.33, n=67) and the δ13cbulk values (r=-0.30, n=66) (fig.4). the correlation with the concretions and the lake level changes is also negative considering the carbon isotopes record (r=-0.31, n=44), whereas there is a positive correlation with the oxygen isotope record of concretion (r=+0.32). hence, for lake ledro the δ18obulk record correlates quite well with lake level changes, with 18o-depleted values corresponding to phases of lake level increasing (figs 2 and 4). on the contrary, lowering of lake level matches with higher δ18obulk values. this confirms that δ 18obulk is can be considered as a reasonably good proxy for lake hydrological changes and lake level, in particular for lakes with simple hydrological budge. δ 13c of carbonate is dependent on carbon isotope composition of the dic, controlled by several processes (e.g., leng & marshall, 2004) including: exchange with atmospheric co2, respiratory activity of aquatic plants, mineralization of organic matter and dic isotopic composition of the inflowing water, influenced by the dissolution of carbonate rocks from the catchment and leaching of soil co2. however, δ 18obulk and δ 13cbulk of lake ledro show a good correlation (fig. 3), which could indicate that data are controlled by the same external factors. period of lower lake level and higher δ18obulk and δ 13cbulk can indicate a decrease of contribution of soil-derived co2 by input water and higher equilibration with atmospheric co2 (zanchetta et al., 2018). whereas wetter period can increase the flush of soil co2 and increasing of recycling of organic matter in a deeper lake (whittington et al., 2015; zanchetta et al., 2018). on the other hand, as horton et al. (2016) pointed out, evaporation causes 18o enrichment in water and 13c enrichment in dic. they suggested that evaporation induces increases in alkalinity (i.e. increased bicarbonate concentration) and drives dic 13c-enrichment through isotopic equilibrium exchange with atmospheric co2 (ca. 8‰ at 25°c in the hco3-co2 system; mook et al., 1974). hence, the highest δ13cbulk values are originated by 13cenriched dic due to equilibration with atmospheric co2 (e.g, leng et al., 1999), enhanced by co2 outgassing linked to strong evaporation (talbot, 1990) and the enhanced residence time. in warm conditions, there is also a strong biological activity leading to enhanced 13cenrichment in the water (siegenthaler & eicher, 1986), if 2000). for the lake ledro record, encrustations and macroscopic components were isolated and used for lake level reconstruction (magny et al., 2009) and isotopically analysed together with the isotopic characterization of the fine-grained carbonate matrix, which could be supposed to be composed by a mix of authigenic calcite and disaggregated calcitic concretions, as evidenced for other marl lakes (von grafenstein et al., 2000; apolinarska & hammarlund, 2009). however, it is reasonable to expect that fine-grained matrix bulk carbonate is mostly related to the general water condition in the upper part of the lake water, where algae photosynthesis occurs driving bio-induced calcite precipitation, whereas concretions are more related to local, plant driven, conditions. in general, in hydrologically open lakes with fast turnover, temperature and the isotopic composition of precipitation entering the lake will be the most important drivers of final δ18o values of carbonates. however, in lacustrine system evaporation influences the isotopic composition of lake water in relation to the residence time and to the morphometric characteristic of the lake itself and local climate (gonfiantini, 1986). in particular, in closed lakes, with long residence times, the effect of evaporation will usually be far more important (li & ku, 1997; leng & marshall, 2004; leng et al., 2006). some lakes nearby lake ledro, with different morphometric parameters and elevation, show a seasonal variation on the isotopic composition of their waters, especially in the epilimnetic values, due to evaporation and, in general, their isotopic composition of water is related to hydrological processes (baroni et al., 2006; perini et al., 2009; natale et al., 2013; flaim et al., 2013). lake ledro turnover time is less than 1 year (0.8 years; casellato & caneva, 1994) but considering that the rivers feeding the lake are dry for most of the year, we can hypothesize that the water isotopic composition is mainly controlled by the rate of evaporation, and the supply of local meteoric precipitation and spring waters. in particular, the rate of evaporation would be important in summer. in this situation, we can assume that the oxygen isotopes of lacustrine carbonates should be mainly interpreted as changes in the hydrological budget of the lake rather than changes in temperature (e.g. roberts et al., 2008; zanchetta et al., 2012). higher δ 18o values of lake water, especially in the epilimnion, and thus higher δ18o of carbonates, should correspond to phases of reduced precipitation with lower contribution from the torrential tributaries and/or increase of evaporation rate (i.e., drier period), while lower δ18o values should correspond to an increase in the amount of precipitation and/or reduction of the evaporation of lake water (i.e., wetter period). however, this can be complicated by temperature changes and by the changes in the isotopic composition of meteoric precipitation, which act as additional factors that ultimately can either amplify or partially suppress the isotopic signal linked to changes in the rate of evaporation (dansgaard, 1964; rozanski et al., 1992; fricke & o’neil, 1999). because lake carbonates (in particular algal bio-induced precipitation) occur mainly in summer, their isotopic composition is skewed toward this season, even if the winter recharge is important in defining the final isotopic budget 103 stable isotopes of carbonate as tracers of lake hydrology not compensated by recycling. the possible influence of detrital materials could be neglected as supported by the near absence of lithoclasts found in the samples analysed (magny et al., 2009). on the other hand, the absence of correlation between δ18o and δ13c of the concretions could be explained by the different origin of the bio-induced carbonates that form the encrustations. each of these encrustations, differentiated by magny in several morphotypes, should be characterized by different “vital offset”, spaces and times in which they formed. this could lead a strong variability of the different isotope compositions, with no clear and apparent correlation with environmental variables. on the contrary, isotopes of bulk carbonates (in particular the fine fraction) better average the lake conditions and, hence, should be good tracers of hydrological changes of lake itself. conclusions in this work, we used the oxygen and carbon isotope signatures of different type of carbonate (bulk and concretions) from lake ledro to test their suitability in detecting lake-level oscillations and, then, whether they are good indicators of hydrological changes of this lacustrine system. our data confirm that different carbonate types have statistically significant different compositions and reflect hydrological changes in different way. in particular, the isotopic composition of bulk carbonate (grain size below 200 μm) shows a correlation with lake level data, allowing us to consider this geochemical signal a good proxy for lake hydrological changes. on the contrary, the concretion isotope values show high variability and did not correlate with lake level changes. this study further indicates that grain size separation would be an efficient and fast method for improving quality of samples in shallow lake deposit rich in concretions. references andersson s., rosqvist g., leng m. j., wastegard s., blaauw m. 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(2012) multiproxy record for the last 4500 years from lake shkodra (albania/ montenegro). journal of quaternary science, 27, 780-789. 106 baneschi i. et al. ms. received: july 13, 2020 revised: october 31, 2020 accepted: november 1, 2020 available online: november 30, 2020 amq abs palombo saccom 177-180.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 177 180 twenty years later: reflections on the aurelian european land mammal age maria rita palombo igag-cnr, c/o dipartimento di scienze della terra, università di roma “sapienza”, roma, italy corresponding author: m.r. palombo <mariarita.palombo@uniroma1.it> abstract: in 1997, some italian palaeontologists proposed a new biochronological assessment for selected italian late pliocenequaternary terrestrial mammal, mollusc and ostracod species. in particular, they proposed a new land mammal age (aurelian lma), emphasising the relevance of the taxonomical and functional turnover that characterised the post-galerian fauna (“extinction of some galerian forms” and the first appearance of “taxa which constitute the core of the modern mammal fauna”). during the following decades, the discovery of several middle pleistocene european local faunal assemblages (lfas) led to a continuous increasing of data and knowledge on the taxonomical status and the chronological range of several large mammal taxa, and new radiometric/absolute dates and magnetostratigraphical information provided substantial evidence, for a new chronological assessment of a number of european lfas. this note aims to present a synthetic overview of the most significant new evidence and some reflections on the transition from the galerian to the aurelian elma, and the significance of the aurelian as european land mammal age. keywords: biochronology, biochronological units, large mammals, middle pleistocene 1. introduction: the fact of the matter the biochronological units (bus) known as land mammal ages (north, nalma, and south american, salma, european, elma, and asian, alma) were initially developed in the first half of the last century in an attempt to chronologically order the north american cenozoic mammalian assemblages (wood et al., 1941). since that time, lmas have been largely, but diversely/ ambiguously used by palaeontologists, and are still loosely defined. the requirements they have to fulfil, indeed, have never been discussed in any stratigraphical code (see lindsay, 2003, pages 213, 220), and the criteria required to create a bu are vague and remain unaddressed. according to tedford (1970, page 602), for instance, a bu (a biological entity equivalent to a discrete natural association of fossil species) could be regarded as non-overlapping and "ecologically adjusted groups of animals with specific geographical limits and chronological range", while lindsay (2003, page 222) defined more explicitly a lma as “a relatively short interval of geologic time that can be recognised and distinguished from earlier and later such units (in a given region or province) by a characterizing assemblage of mammals”. the first/last historical appearance (fha/lha) (palaeobiological events inferred on the basis of the sum of known, palaeobiological data provided by the fossil record derived from strata from the focal geographical region), the peculiar taxonomical composition and ecological structure of the mammalian fauna (which make a bu different from the earlier and later ones recorded in the same geographical area), are the key factors to consider to correctly identify a bu, whichever its chronological range should be. the known lowest and highest stratigraphical occurrence of a taxon in a given geographical area (stratigraphical datum), however, does not necessarily correspond to its first and last appearance in the time (palaeobiological datum). the finding of a taxon, regarded as a biological chrostratigraphical marker of a bu (sensu lindsay, 2003) in stratigraphical levels significantly older/younger than those previously providing its fossil record may, for instance, substantially change the chronological extent of the bu to which it belongs, without changing its theoretical definition. this in turn implies a new assessment and definition of the bus directly preceding/succeeding in time the focal one. in addition, increasing palaeontological and stratigraphical data might allow to better discriminating bioevents, on the one hand highlighting, the gradual transition between successive bus, but, on the other, blurring a clear identification of the bus. as a result, any biochronological scheme, and the definition and temporal extension of a bu, even if dependable, are open to change because depending on the available data,. this note aims to present the main evidence suggesting to revise the definition of the aurelian bu (as provided at the time it was proposed by gliozzi et al., 1997) and its significance as elma, and some preliminary reflections on the issues related to the transition from the galerian to the aurelian elma. a more exhaustive discussion will be provided elsewhere. 2. the aurelian biochronological unit: a reappraisal the aurelian bu was introduced in 1997 in the context of a new biochronological assessment proposed by a team of italian palaeontologists for selected italian late pliocene-quaternary terrestrial mammal, mollusc and ostracod species (gliozzi et al., 1997, page 372). the italian researchers recommended the new aurelian land https://doi.org/10.26382/aiqua.2018.aiquaconference mammal age (lma) for the late middle-late pleistocene mammalian fauna, i.e. from marine isotopic stage (mis) 10 to mis 2, emphasising the relevance of the taxonomical and functional turnover characterising the transition from the galerian to the post-galerian fauna (“extinction of some galerian forms, such as the megacerine cervids of the megaceroides (recte praemegaceros) verticornis group, megaloceros savini and the more archaic elaphine deer”, and the first appearance of “taxa which constitute the core of the modern mammal fauna”) (gliozzi et al., 1997, page 372). the characterisation of the new lam was mainly based on the taxonomical composition of some italian local faunal assemblages (lfas) found in “deposits, which date to the late middle pleistocene and the late pleistocene” (gliozzi et al., 1997, page 372). the fha of canis lupus, ursus spelaeus and magaloceros giganteus (mentioned as regards to their fha in the oldest aurelian faunal unit) were the bioevents chosen by gliozzi et al. (1997) to identify the beginning of the aurelian bu, but what about the time of the fha of these taxa in europe? new evidence dates back the c. lupus presence to mis 14(?) – mis 13 (galería gii, atapuerca, spain) (rodriguez et al., 2011; álvarez-posada et al., 2018). a small wolf, canis lupus lunellensis, was already reported from lunel viel (france), a site dating to about 400350 ka (brugal and boudadi-maligne, 2011 and references therein), and the modern wolf is also recorded, together with m. giganteus, during mis 11 in some european lfas, for instance, in britain (stewart, 2008 and references therein). the time of the lowest stratigraphical occurrence in europe of u. spelaeus cannot firmly be established due to some confusing taxonomical treatments of some specimens (most lacking sound taxonomical diagnostic features), likely belonging to one or the other species of the cave bear lineage known in the middle pleistocene: ursus deningeri and its putative descendant u. spelaeus. in schreve’s opinion (schreve, 2001, page 1694), for instance, in the “swanscombe mammal assemblage-zone” (mis 11) “the early middle pleistocene form ursus deningeri reichenau” was “superseded by the more advanced form ursus spelaeus”. the deninger’ bear, conversely, has been reported even from significantly younger lfas, such as orgnac 3 levels 7-3 (france) (e.g. sam, 2009). the available data, moreover, indicate that some among the large mammals commonly found in the aurelian lfas were already present either in the postjaramillo early pleistocene (e.g. palaeoloxodon antiquus, crocuta crocuta, lynx pardinus, sus scrofa), or in the early middle pleistocene (mis 19 mis 12) (e.g. ursus arctos, ursus thibetanus, vulpes vulpes, cuon alpinus, felis silvestris, stephanorhinus hemitoechus, bos primigenius, dama clactoniana, bison priscus, bos primigenius, maybe rupicapra pyrenaica), or at least during mis 11(e.g. hippopotamus ex gr. h. amphibius, modern roe deer capreolus capreolus, m. giganteus), suggesting to predate the beginning of the aurelian bu (fig.1, 2). assuming that the hypothesis could be correct, the question arises about the time of the transition from the galerian to the aurelian bu. according to gliozzi et al. (1997, page 372), the late galerian fauna, to which only the fontana ranuccio f.u. was referred, “is characterised by the total disappearance of typical villafranchian taxa with the exception of homotherium” and by the presence of “the red fig. 1 chronological range of selected middle and late pleistocene european proboscideans, primates, and carnivora. 178 palombo m.r. deer subspecies cervus elaphus eostephanoceros. as regards to the “villafranchian” large predators, new data indicate that the saber-toothed cat was still present during mis 3 (reumer et al., 2003), and panthera gombaszoegensis in deposits correlated to mis 9 or mis 10 (marciszak, 2014). it is worth noting, that fontana ranuccio lfa (anagni basin, central italy), regarded by gliozzi et al. (1997) as one of the most representative late galerian site and epitome of the homonymous f.u., was at that time dated to 0.458 ma (mis 12). the age of most of the european lfas successively correlated to the fontana ranuccio lfa or ascribed to the homonymous f.u. fall in the chronological range of mis 13 and mis 12. recently, pereira et al. (2018) obtained a 40ar/39ar age of 408±10 ka for the archaeological level (unit fr4) of fontana ranuccio, roughly corresponding to mis 11 climatic optimum, in some agreement with the fauna ecological structure. according to the new date, the lfa would fall in the extended chronological range of the aurelian bu, together with other roughly coeval lfas from the same geographic area already regarded as “aurelian” (e.g. isoletta, lademagne). although this fact could not substantially affect the definition of the “late galerian”, the question about the significance of c. e. eostephanoceros as a biological chrostratigraphical marker remains unsolved. in the gaudo san nicola lfa, a site chronologically and geographically close to fontana ranuccio, indeed, sala et al. (2014) claimed the presence of the archaic cervus eluphus acoronatus subspecies, considering c. e. eostephanoceros a young synonymous of the former. all in all, the available data evidence the gradual, progressive transition from a elma to the successive one during the late early and middle pleistocene, as well as the complexity in properly detecting and defining such elmas. 3. remarks the sum of evidence highlights the gradual modification of the structure of the mammalian palaeocommunities, leading to the configuration of the aurelian ones (e.g. palombo, 2017), and, in turn, the difficulty to properly define discrete lmas succeeding each other during a short geological time. the original lma concept, indeed, implicitly implies a long persistence in time and a wide geographical extent for each unit, given that the mean duration of a large mammal cenozoic species is about 3 ma (see prothero, 2014 as regards to the north american mammals). therefore, the shorter the time slice is, the more difficult to properly define a lma could be. any analysis performed on short geological time periods, for instance, may sometimes force researchers to consider taxa at a low taxonomical rank, thereby increasing the risk of disagreements in the taxonomies applied by the authors. additional drawbacks may concern the need of a particularly detailed chronology, in contrast with a proportionally low number of lfas with firm chronological constrains. an alternative approach may be to focus more on the detection of "ecologically adjusted groups of animals with specific geographical limits and chronological range" than merely on fha/lha bioevents. following this line of reasoning, taking into account: i) the climatic and environmental changes (e.g. the increase in summer temperatures, and average forest expansion during interglacial phases) that occurred since mis 11; ii) its peculiarity with respect to the previous middle pleistocene interglacials (higher level than present-day sea related to the collapse of greenland and west antarctica ice sheets, greenhouse gas-driven climate warming pattern of insolation variability matching the holocene one) (e.g. oliveira et al., 2016 and references therein), iii) the number of fha reported at that time (figs. 1, 2), 179 reflections on the aurelian elma fig. 2 chronological range of selected middle and late pleistocene european perissodactyla and cetartiodactyla. iv) the functional diversity characterising the large mammal fauna since mis 11 (palombo, 2016), the hypothesis to chronologically extend the aurelian bu to include mis 11 seems to be the most reasonable. as a result, the definition and biochronological significance of the “late galerian” fauna, which according to gliozzi et al. 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(2009) etude paléontologique, archéozoologique et taphonomique des grands mammifères du site pléistocène moyen d’orgnac 3 (ardèche, france) phd dissertation, university of perpignan, france. schreve d. (2001) differentiation of the british late middle pleistocene interglacials: the evidence from mammalian biostratigraphy. quaternary science reviews, 20(16-17), 1693-1705. stewart j.r. (2008) the progressive effect of the individualistic response of species to quaternary climate change: an analysis of british mammalian faunas. quaternary science reviews, 27(27-28), 2499-2508. tedford r.h. (1970) principles and practices of mammalian geochronology in north america. in proceedings of the north american paleontological convention, 1 (part f), 666-703. wood 2nd h.e., chaney r.w., clark j., colbert e.h., jepsen g.l., reeside jr j.b., stock c. and committee (1941) nomenclature and correlation of the north american continental tertiary. bulletin of the geological society of america, 52(1), 1-48. 180 palombo m.r. ms. received: may 2, 2018 final text received: may 14, 2018 amq abs sechi et al saccom 189-192.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 189 192 luminescence dating of a middle late holocene lower shoreface, sw sardinia (italy) daniele sechi 1, stefano andreucci 2, giovanni de giudici 2, vincenzo pascucci 1 1 università degli studi di sassari, dipartimento di architettura design urbanistica, alghero, sassari, italy 2 università di cagliari, dipartimento di scienze chimiche e geologiche, cagliari, italy corresponding author: d. sechi <dasechi@uniss.it> abstract: geochronological framework of middle-late holocene coastal succession are usually based on radiocarbon dating method. homolithic sandy bodies characterize lower shoreface deposits and shells are often the only readily available biogenic materials for radiocarbon dating. however, multiple processes of erosion and deposition frequently affect sediment-grains and biological materials. as a consequence, 14c dating performed on shells often may under or overestimate the true age of the hosting deposits. this study highlights that luminescence dating is better suited to investigate sedimentary body formed in high energetic environments because directly dates the age of the final burial event. moreover, combining the quartz and k-feldspar derived ages a more robust dataset and internal independent age controls can be provided. keywords: sar-osl, pirir150, geochronology, radiocarbon dating, “old shell” problem 1. introduction in the last decade luminescence has become one of the most used method for dating siliciclastic-rich quaternary deposits (pascucci et al., 2014). nevertheless, its application is usually limited to the pleistocene while radiocarbon method is chosen for dating holocene successions (pascucci et al., 2014; 2018). in particular, 14c method is widely applied in shallow marine-coastal studies throughout the world but precise dating of lower shoreface deposits remains a major task. shoreface deposits of wave-dominated system are characterized by homolithic sandy bodies transported basinward from the coastline by return flows induced by major storms. in this highly energetic environment, shells are usually the only readily available biogenic materials for radiocarbon dating. however, shells may suffer of multiple reworking processes prior the final burial event and thus 14c may overestimates the ages of storm beds producing stratigraphic discrepancies. to overcome this problem an alternative or independent geochronological approach is needed. luminescence methods date the time elapsed since siliciclastic minerals (quartz and feldspar) were last exposed to day-light and thus directly provide the age of the final burial event (madsen & murray, 2009). aim of this work is therefore to provide a luminescence-based chronological framework for a middle-late holocene shoreface succession and compare with published radiocarbon ages provided by romano et al. (2017). moreover, luminescence ages will be provided using three different protocols such as sar-osl on quartz mineral along with ir50 and pirir150 on kfeldspar grains (madsen & murray, 2009; reimann t. & tsukamoto 2012). although these protocols share some common features, they also have their own specific traits and can be considered independent from each-other and thus used for age comparisons. 2. material and methods cala domestica (sw sardinia, italy; fig. 1) is a narrow 100 m wide and 450 m long bay carved in the lower cambrian meta sandstone and dolostones. it is characterized by a well-developed sandy pocket beach backed by an active dunefield system (fig. 1). the sediments nourishing the system are mainly bioclastic materials transported onshore from sea grass meadows during storms and minor siliciclastic grains carried by nw/se longshore current and/or by the seasonal riu guttu stream (fig.1). samples for luminescence and shells for 14c were collected from a 3-m long sediment core drilled in the shoreface (-13m below the present-day sea level). the sediment core was taken throughout opaque cylindrical plastic tube in order to avoid exposition of sediments to day-light and then opened under red subdued light. from the studied core two marine shells s1 and s5 were collected and the derived calibrated before present (bp) radiocarbon ages are already published by romano et al. (2017). a total of six luminescence samples were collected on the same core (fig.2). in particular iso0 at the very top, iso1 and iso5 at the same position of the shells collected for 14c and the remnant samples (iso2, iso3, iso4) every ~50 cm. all samples underwent chemical treatment at the sassari luminescence laboratory to isolate the 180-90 φm pure fraction of quartz and kfeldspar grains. single aliquot regenerative protocol (sar) for quartz and infra-red stimulation at 50 °c (ir50) along with post infra-red, infra-red stimulation at low https://doi.org/10.26382/aiqua.2018.aiquaconference 190 sechi d. et al. tab.1 summary of quartz luminescence dating results. table reports sample code and depth of sampling. for each mineral dosimeter chosen for luminescence dating, the luminescence protocol/signal used are reported with the estimated burial palaeodose (de, gy), environmental dose rate (dr, gy/ka) and calculated final burial ages expressed in years (a) from present (ad 2017). fig.1 a) the studied area. a) location of sardinia island in the mediterranean region where it occupies a central position. the map of sardinia, reported the main cities (black circles). the red square highlight the position of studied area in the sw of island. b) main bedrock lithologies outcropping around the study area. c) satellite view of cala domestica bay with drilling station. 191 temperature 150 °c protocols (pirir150) on k-feldspars were applied for luminescence burial palaeodose (de) measurements (madsen & murray, 2009; reimann t. & tsukamoto, 2012). enviromental dose rate (dr) calculations corrected for cosmic rays and water content contributions are based on high resolution gamma spectrometer. 3. results table 1 reports luminescence dataset for the collected samples (fig. 2). quartz and k-feldspar signals pass all laboratory tests. these provide very good results for the three main reliability check-criteria: recycling, recuperation and dose recovery. quartz (oslsar) and feldspar (ir50, pirir150) signals gave in average recycling ratios within the 10 % of unity and recuperation less than 5% of natural de. dose recovery ratios are all close unity, 1 ±0.02 (sar-osl), 1.00±0.01 (ir50) and 0.96 ±0.02 (pirir150). these data confirm the suitability of protocols and dosimeters chosen for dating the sediment of cala domestica. given that k-feldspar suffers of fading (partial loss of signal recovered throughout the time) the g-value (% of loss per decade) was tested. the ir50 and pirir150 show an average fading ratio respectively of 3.86 and 0.89 %/dec. and thus used for correcting final feldspar ages. quartz sar -osl yield ages ranging from the bottom up of 4800±300 to 540±50 a. feldspar ir50 and pirir150 show ages respectively from 4217±87 and 4347±133 a to 403±12 and 433±41 a (tab.1). 3. discussion and conclusion three meters of holocene core collected on shallow marine (lower shoreface) deposits, far off cala domestica bay, is dated using luminescence and 14c methods. this study sheds a light on strenghths and weaknesses of these two approaches. figure 2 compares the three sets of luminescence dating (sar, ir50 and pirir150) with the radiocarbon ages. estimated luminescence ages using the two mineral dosimeter (quartz and feldspar) and different luminescence signals are in stratigraphic order downward the core. the reliability of estimated palaeodose and ages is supported by the pretest results. the uppermost sample (iso0) yield null or small residual palaeodose for the three protocols applied. this suggests that all different luminescence signals are being well zeroed by day-light at depth of 13 m. moreover, consistency and increasing of the ages downward confirm that mineral dosimeters well recover the palaeodose (burial time) elapsed from the last exposition and allow to exclude the presence of partial bleached inherit signal issue (incomplete zeroing). although, sar-osl ages slightly overestimate the ir50 and pirir150 ones, these agree each-other within 1 sigma uncertainties. in particular, kfeldspar-derived ages obtained for iso5 (bottom of core) confirm the 14c age of 4435-4290 cal bp (romano et al., 2017). the fading rates obtained for pirir150 are significantly lower than those form ir50 (tab.1) suggesting the better stability of pirir150 signal over time and the potential of the protocol for dating recent to very recent sedimentary bodies. the iso1 sample shows luminescence ages consistently younger than 960-860 cal bp 14c (fig. 2). this ca. 500 a discrepancy between luminescence and 14c ages most likely is due to the multiple reworking processes that shells and sediment-grains suffering in the luminescence dating of a middle late holocene lower shoreface, sw sardinia fig. 2 on the right the stratigraphic reconstruction of drilled core and position of radiocarbon and luminescence samples collected. the radiocarbon ages (romano et al., 2017) are reported against the estimated sar, ir50 pirir150 luminescence ages. on the left, the plot of geochemical enrichment factor (ef) along the core depth published by romano (2017). only element anthropogenically enriched (ef>1.5) are reported. shoreface environment. in particular, shells may be temporarily stored in the foreshore part of the beach system prior to be finally buried in the lower shoreface as a consequence of major storms. the anthropogenically enriched elements (hg, pb and zn) measured along the studied core by romano et al. (2017) show a strong enrichment in the first 20 cm of the core clearly referable to the recent mine activity (fig. 2). whereas based on the 14c available age a small peak observed at ca. 60 cm were associated as well with ore exploitations in pre-industrial times but with no possibility to refer this activity to the phoenician, romans, pisans or middle ages. however, luminescence ages point the first peak to a post-romans ore exploitations better constraining the mining activity at the study area. the carried out study highlights that in highly energetic environments such as lower shoreface multiple reworking processes frequently affect sediment-grains and biological materials. as a consequence of this, 14c dating performed on shells might under or overestimate the final burial age of the host deposits. therefore, luminescence dating is better suited to investigate homolithic sedimentary body because it directly dates the mineral grains sun-exposition, transport and accumulation history. moreover, using different luminescence signals and dosimeters allow to have a better knowledgement of sedimentary depositional history and internal independent age controls. references madsen a.t., murray a.s. (2009) optically stimulated luminescence dating of young sediments: a review. geomorphology, 109, 3-16. pascucci v., de falco g., del vais c., sanna i., melis r.t., andreucci s. (2018) climate changes and human impact on the mistras coastal barrier system (w sardinia, italy). marine geology, 395, 271284. pascucci v., sechi d., andreucci s. (2014) middle pleistocene to holocene coastal evolution of nw sardinia (mediterranean sea, italy). quat. int., 328 -329, 3-20. reimann t., tsukamoto s. (2012) dating the recent past (<500 years) by post-ir irsl feldsparexamples from the north sea and baltic sea coast. quaternary geochronology, 10, 180-187. romano e., de giudici g., bergamin l., andreucci s., maggi c., pierfranceschi g., magno m.c., ausili a. (2017) the marine sedimentary record of natural and anthropogenic contribution from the sulcisiglesiente mining district (sardinia, italy). marine pollution bulletin, 122(1-2), 331-343. 192 sechi d. et al. ms. received: may 6, 2018 final text received: may 14, 2018 amq abs vigliotti ruberti tepro 247-251.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 247 251 campania grey tuff and anthropogenic tuff cavites in the southern metropolitan area of caserta (southern italy) marco vigliotti, daniela ruberti engineering department, campania university "l. vanvitelli"; aversa (ce), italy corresponding author: d. ruberti <daniela.ruberti@unicampania.it> abstract: the late quaternary geological evolution of the northern campania plain was affected by the volcanic activity of the phlegrean field. the geological features of the campania grey tuff (cgt, ~39 ky), deposited on the whole campania plain, were reconstructed along a transect from the northern boundary of the metropolitan area of naples up to caserta. since the tuff has good mechanical properties, it was involved since historical times in an extensive mining activity, from which a very dense network of quarries and underground cavities was inherited, strongly related to the lithofacies distribution. we provided a first geological underground database of the metropolitan area of caserta, north of naples, and analyzed the hazard aspects related to the mining activities. keywords: campania plain, campania grey tuff, urban data management, database, tuff cavity 1. introduction the late quaternary geological evolution of the northern campania plain has been affected by the volcanic activity of the phlegrean field. among the volcanic events that have characterized this area, the one that emplaced the campanian grey tuff (~39 ky; de vivo et al., 2001) was the most important. thick pyroclastic flow deposits blanketed the whole plain and represented the substrate for the following holocene sedimentation, with thicknesses of tens of metres and a depth from the ground level reducing toward north-east, close to the apennines foothills (ortolani & aprile, 1985; bellucci, 1994; putignano et al., 2007; ruberti et al., 2014). the campanian grey tuff shows different lithofacies both laterally and with depth (di girolamo, 1968; cappelletti et al., 2003; ruberti et al., 2014). since the tuff has good mechanical properties, it was involved since historical times in an extensive mining activity, from which a very dense network of quarries and underground cavities was inherited, strongly related to the lithofacies distribution. in many urban centers of the campania plain (e.g., naples, aversa and surroundings), cavities have been reported in specific geological investigations although their real extent is almost unknown. in these towns the underground mining activities were performed to extract tuffs for buildings. the urban development has sealed every signal of the presence of cavities, which thus represent a geological hazard and contribute to subsoil instability in many places (brinkmann et al., 2008; parise, 2010; scotto di santolo et al., 2018). in a correct urban management, the knowledge of the city subsoil is a priority, as the presence of cavities may easily trigger the collapse of the shallow or deeper soils (e.g., ciotoli et al., 2015; guarino et al., 2017). it is herein reported a preliminary study carried out on the small area of the campania plain, north of naples, along a transect from the northern boundary of the naples municipality to caserta. the study area is characterized by a flat topography and was interested by the volcanic activity of the phlegrean field. tuffs and cinerites are the main lithologies recognized in the first tens of metres. since the tuffs have good mechanical properties (i.e. high compression strength, low specific weight) and are found at a shallow depth from ground level, they were involved since historical times in an extensive underground mining activity. towards the apen fig. 1 geological map of the study area (modified from ruberti et al., 2014). yellow lines indicate the geological profiles in fig. 2. https://doi.org/10.26382/aiqua.2018.aiquaconference nines the tuff lies only a few metres below the ground level. this resulted in a strong development of quarrying through open pits (ruberti et al., 2014). the present investigation tries to address the complex interaction between geological framework and anthropic activities related to urban subsoil of the metropolitan area of caserta, north of naples; data were managed in a gis so as to provide a first geological underground database and a preliminary analysis of the hazard aspects related to the mining activities. 2. study area the examined area, about 54 km2 wide, corresponds to the central part of the campania plain (fig. 1), north-east of the phlegrean fields, that is characterized by a flat morphology between 95 and 20 m a.s.l. in this area the subsoil is formed by the succession of different units composed of volcanoclastic deposits, in particular related to the campania grey tuff (cgt; 39 ky b.p; de vivo et al., 2001) and neapolitan yellow tuff (nyt; 15 ky b.p.; deino et al., 2004) pyroclastic eruptions. the cgt deposits were settled on the whole campania plain, giving rise to a thick (up to 40 m), laterally continuous, volcanoclastic unit. different lithofacies can be recognized within the cgt mostly basing on the different mineralogic composition (di girolamo 1968; cappelletti et al., 2003; morra et al., 2010). on the whole, from top to bottom the succession of cgt lithofacies is characterized by an upper incoherent part, represented by the cinerazzo (cz) followed by the coherent zeolitic yellow tuff (tgz) and/or grey tuff (tg), piperno tuff (tp), and pipernoide (pp) ones. close to the bottom of the unit, a soft lithofacies occurs, called cinerite (cn). these lithofacies greatly vary in thickness and occurrence vertically and laterally toward east or north from the source area. the uppermost unit of the reconstructed stratigraphic succession is represented by the thin grey, loose ashy deposits of the nyt, which are locally separated from underlying cgt by a paleosol (putignano et al., 2007; santangelo et al., 2010; ruberti et al., 2014). the good mechanical characteristics of the tuff lithofacies justify the presence of numerous quarries and/or cavities, according to the availability of adequate thicknesses of coherent lithofacies (i.e. tgz, tg). 3. methods the main geologic features of the study area were obtained using lithostratigraphic logs from boreholes 248 fig. 2 geological cross-sections (tracks in fig. 1): (1) cinerite,(2) grey tuff, (3) zeolitic yellow tuff, (4) pebble tuff, (5) incoherent facies of cgt, (6) paleosoil, (7) pyroclastic deposits younger than cgt, (8) soil, (9) pre-cgt deposits. quarries and cavities are not to scale. dotted line indicates the upper and lower limits of the cgt deposits. vigliotti m., ruberti d. 249 reaching the depth of 30–35 m, available from different sources (environmental agencies, municipality offices, professional studies, unpublished researches, etc.), and from the analysis of quarry walls (in the northern part of the study area) exposing 15–20 m of deposits. the marker key to correlate the different units was represented by the cgt volcaniclastic deposits. the lithological data were collected into a relational geodatabase of well-log stratigraphies, which were further interpreted and homogenized in terms of lithologic units, also containing the related thickness and upper and lower-boundary elevations a.s.l, with the aim of facilitating the development of a 3d geological model (putignano et al., 2007; see also methods in velasco et al., 2012). previous studies have highlighted the presence in the area of numerous cavities. in a first step, a database was elaborated to organize previous data and the results of new, specific investigations. a gis project was designed to manage the georeferenced database and plot the cavity distribution on the numerical cartography in 1:5000 scale. many cavity maps were digitized, georeferenced and imported in the gis environment. in such way, they can be easily located under the built areas. where plan views were not available, the cavities and/or the access wells were reported only as points. the shallow quarries have been located through interpretation of aerial multitemporal photos and analysis of historical cartography (see also ruberti et al., 2014). 4. results and discussion the analysis of geological data has revealed some common features for the considered area (fig. 2): i) the occurrence of coherent zeolitic yellow tuff was the main trigger for cavity development, mainly for extraction purpose; mean thickness is 8 m. the zeolitized yellow welded tuff is formed by ashy matrix with rounded lapilli and dispersed block pumice clasts. locally, few and scattered coarse scoriae are present; ii) below the zeolitic yellow tuff, slightly welded pyroclastic soils and ash layers occur showing different compaction. iii) in the slightly lithified upper part ash is characterized by abundant pebbles/breccias of volcanic tuff (cappellaccio or pebble tuff); iv) a metre thick paleosoil underlines the upper limit of the cgt. the former is formed by brown, silty-sand, pyroclastic unit with small rounded and altered pumices. the upper deposits mainly consist of whiteyellowish and greyish cinerite in which whitish pumfig. 3 example of cave dug into the tuff. a) view of a chamber with an access well on top; b) details of access realized with steps directly carved into the tuff. campania grey tuff and cavities ice layers intercalate, mostly related to more recent eruptions of the phlegrean fields. towards east the thickness is reduced to a few metres (about 2 m). on the whole, the development of artificial cavities and quarries was strongly linked to the lithology of the cgt and the related thickness. in the southern part of the study area a dense cavity network characterizes most of the historical town centers whereas towards east the cavities are associated with and/or replaced by open pits developing for almost 10-15 m down from the surface. the cavities develop within the yellow tuff in which large scoriae, pumices and lava blocks can be recognized. pipes are common and very often the weak, loosely packed deposits favoured the beginning of the quarring activity (fig. 3). the digging of cavities initially involved an excavation carried out as a "bottle" or a "bell" from the ground level down to the tuff unit, developing at depth according to its thickness. during excavation, access points were realized (fig. 3a) through the poorly lithified or loose deposits, with a square or pseudo-circular cross-section; sometimes they were supported by containment walls made of tuff bricks resting on the lower lithoid tufaceous bank. a single vertical excavation is sometimes added at certain distance, so as to determine in depth the coalescence of several chambers, also through the construction of narrow tunnels or wide passages. access shafts were often realized with a system of stairs with one or more ramps, with steps directly carved into the tuff (fig. 3b). eastwards, the reduced thickness of the post-cgt deposits allowed the easy mining of tuff in open pits from the ground surface. all the quarries are almost similar: they are rectangular holes about 1–4 hectares large with almost 20-m high, vertical steep walls. a previous study (ruberti et al., 2014) has highlighted that most of these quarries are nowadays partially filled with earthy materials and used for agricultural purposes, whereas others are sites of illegal waste disposal; some of them lie buried in the present urban area. the mining activities were responsible for the reduction, up to the complete removal, of the yellow tuff. moreover, the tuff mining resulted in the reduction of the depth of the quarry bottom in respect to groundwater, leading to a further critical environmental condition. 5. concluding remarks the study provides a first database of the geological underground in the metropolitan area of caserta, north of naples. the database is designed to be managed into a gis environment in order to provide a detailed 3d geological reconstruction. the gis project was implemented with data on tuff cavities and quarries from the same area. quarrying for building materials was the main trigger for cavity development in the historical center of the towns and their occurrence is linked to the availability of underground well-lithified materials. the analysis of the urban expansion since the beginning of the 19th century has revealed a close relationship between the occurrence of cavities in the subsoil and the expansion of the city until the 1970s, when the use of cement completely replaced 250 fig. 4 a quarry pit showing typical vertical walls, partially filled for agricultural purpose. vigliotti m., ruberti d. the extraction of tuff. the knowledge of such underground system represents a useful contribution to the hazard evaluation in densely urbanized areas. on the other hand, the recognition of the open pits for tuff extraction and the assessment of their current use provides information for land management and allows the assessment of possible pollution hazard. references bellucci f. (1994) nuove conoscenze stratigrafiche sui depositi vulcanici del sottosuolo del settore meridionale della piana campana. boll. soc. geol. it., 113, 395-420. brinkmann r., parise m., dye d. (2008) sinkhole distribution in a rapidly developing urban environment: hillsborough county, tampa bay area, florida. eng. geol. 99 (3-4), 169-184. cappelletti p., cerri g., colella a., de’ gennaro m., langella a., perrotta a., scarpati c. (2003) posteruptive processes in the campanian ignimbrite. miner. petrol., 79, 79-97. ciotoli g., ferri g., nisio s., succhiarelli c. (2015) the underground cavities in the territory of rome: typologies, distribution and sinkhole susceptibility. in: hypogea 2015, proceedings of international congress of speleology and artificial cavities rome, march11/17 2015, 433-439. de vivo b., rolandi g., gaus p.b., calvert a., bohrson w.a., spere f.j., belkin h.e. (2001) new constraints on the pyroclastic eruptive history of the campanian volcanic plain (italy). miner. petrol., 73, 47-65. deino a.l., orsi g., de vita s., piochi m. (2004) the age of the neapolitan yellow tuff caldera-forming eruption (campi flegrei caldera-italy) assessed by 40ar/39ar dating metod. j. volcanol. geotherm. res., 133, 157-170. di girolamo p. (1968) petrografia dei tufi campani: il processo di pipernizzazione (tufo tufo pipernoide piperno). rend. accad. sci. fis. mat., ser. 4, 35, 329-394. guarino p., santo a., forte g., de falco m., niceforo m. (2017) analysis of a database for anthropogenic sinkhole triggering and zonation in the naples hinterland (southern italy). natural hazards, 91, 173-192. morra v., calcaterra d., cappelletti p., colella a., fedele l., de’ gennaro r., langella a., de’ gennaro m., mercurio m. (2010) urban geology: relationships between geological setting and architectural heritage of the neapolitan area. in: beltrando m., peccerillo a., mattei m., conticelli s., doglioni c. (eds), the geology of italy: tectonics and life along plate margins. j. virtual explor., electron ed, 36, paper 27. ortolani f., aprile f. (1985) principali caratteristiche stratigrafiche e strutturali dei depositi superficiali della piana campana. boll. soc. geol. it., 104, 195 -206. parise m. (2010) hazards in karst. in: sustain. karst environ. dinaric karst other karst reg. series on groundwater. ihp-unesco, plitvice lakes, croatia, 155-162. parise m., galeazzi c., bixio r., dixon r. (2013) classification of artificial cavities: a first contribution by the uis commission. in: filippi, m. and bosak, p. (eds), proc. 16th int. congr. speleol., 21-28 july 2013, 2, 230-235. putignano m.l., ruberti d., tescione m., vigliotti m. (2007) evoluzione tardo quaternaria del margine casertano della piana campana (italia meridionale). boll. soc. geol. ital., 126 (1), 11-24. ruberti d., vigliotti m., marzaioli r., pacifico a., ermice a. (2014) stratigraphic architecture and anthropic impacts on subsoil to assess the intrinsic potential vulnerability of groundwater: the northeastern campania plain case study, southern italy. environ. earth sci., 71, 319-339. santangelo n., ciampo g., di donato v., esposiro p., petrosino p., romano p., russo ermolli e., santo a., toscano f., villa i. (2010) late quaternary buried lagoons in the northern campania plain (southern italy): evolution of a coastal system under the influence of volcano-tectonics and eustatism. ital. j. geosci. (boll.soc.geol.it.), 129(1), 156 -175. scotto di santolo a., forte g., santo a. (2018) analysis of sinkhole triggering mechanisms in the hinterland of naples (southern italy). engineering geology, 237, 42-52. velasco v., gogu r., va´zquez-sune` e., garriga a., ramos e., riera j., alcaraz m. (2012) the use of gis-based 3d geological tools to improve hydrogeological models of sedimentary media in an urban environment. environ. earth sci., 68 (8), 2145-2162. 251 campania grey tuff and cavities ms. received: may 8, 2018 final text received: may 24, 2018 252 amq30(1) 4 yurchenko 41-49 available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 30 (1), 2017, 41 49 vegetational evolution in the transcarpathian lowland (ukraine) during the middle pleniglacial (pollen study of the beregovo i site) tamara yurchenko taras shevchenko national university of kyiv, kyiv, ukraine corresponding author: t. yurchenko <aramant@ukr.net> abstract: a reconstruction of the vegetational evolution during the middle pleniglacial has been carried out on the basis of a pollen study of the loess-palaeosol deposits from the upper palaeolithic site beregovo i (transcarpathian lowland). the stratigraphy of the site is based on the quaternary stratigraphical framework of ukraine, the archaeological data and ams 14c-dating. at the end of the uday time of loess formation (early pleniglacial), forest-meadow ecosystems (with predominance of birch and pine in the forests) existed under the cold and wet climate of a stadial. three main stages of vegetation development (with several phases) have been identified within the vytachiv time (the middle pleniglacial). during the beginning of the first stage (the early vytachiv time, the formation of the lower cambisol), coniferous and broad-leaved forest grew under the rather warm climate of an interstadial. the second phase of this stage was characterized by a spread of a forest-steppe. the warm interstadial climate, indicated by the growth of broad-leaved trees, became less humid. during the second stage of the middle pleniglacial (the middle vytachiv time, represented by loess-like deposits), a boreal forest-meadow vegetation spread under the cool climate of a stadial. the aurignacian cultural horizon corresponds to the deposits of this stadial. three phases of vegetation development have been recognized within the third stage of the middle pleniglacial (the late vytachiv time). during the first phase (the beginning of the upper cambisol formation), there existed a forest-steppe with predominance of boreal trees. the climate was relatively cool and corresponded to a transition from a stadial to an interstadial. the second phase of this stage (the formation of the upper cambisol) was characterized by forest-meadow vegetation with a spread of broad-leaved trees. this phase corresponds to an interstadial warming. during the third phase (the transition from the cambisol formation to the incipient pedogenesis, ams dated to 27-26.6 ka uncal bp), an elm-hornbeam forest with admixture of spruce grew on fertile loamy soils, and pine-birch forest occupied the sandy terraces. the climate was still warm and humid. after the end of the middle pleniglacial (the beginning of the bug time), there occurred a spread of meadow vegetation. the decline of arboreal and broad-leaved vegetation indicated the much colder climate of a stadial. the reconstructed vegetation composition of the site demonstrates that the microclimate of the low terrace of the tysa river was milder than in the sites located on the high river terraces. broad-leaved trees were permanently present in the site vicinities: their pollen percentages increased during the periods of the formation of the interstadial soils and drastically decreased during the times of reduction of forest areas and formation of non-soil deposits. this enables the suggestion that refugia of broad-leaved trees could survive in the transcarpathian lowland during the stadials of the pleniglacial (at least before the last glacial maximum). keywords: pollen analysis, palaeovegetation, palaeoclimate, pleniglacial refugia of broad-leaved trees, beregovo i, ukraine. 1. introduction a study of palaeovegetation and palaeoclimate of the transcarpathian lowland is of a particular interest because this area, protected by the mountain ranges from the north and east, has less cold and continental climate than the plains of eastern europe. it might be suggested that it was suitable for the existence of refugia of broad-leaved trees during the pleniglacial. actually, this area is the easternmost part of the middle danube lowland but, on the other hand, its vegetation was formed in connection with the ukrainian carpathian geobotanical province (barabych, 1977). thus, a reconstruction of the palaeovegetation of the ukrainian transcarpathia provides the bridge between central and eastern europe. the whole area of the transcarpathian lowland tectonically corresponds to the transcarpathian depression, but its topography is quite diverse. accumulative alluvial plain of the north-west (the mukachevo lowland) is replaced to the south-east by erosion-accumulative hilly terrains (the solotvynska area). in the east, there is the vygorlat-hutyn ridge of neogene volcanic origin, and separate volcano hills are scattered in the southeast (vakhrushev et al., 2010). the transcarpathian depression is filled with neogene sediments − molasses and lagoonal-alluvial deposits. the quaternary deposits form the continuous cover on the lowland. they are mainly represented by alluvial deposits, which are frequently overlain by loess-palaeosol cover. the climate of the area is very mild as for eastern europe. at the beregovo town, the average july and january temperatures are +20°c and +3°c, respectively. the maximum july temperature is 40°c, the minimum january temperature is -28°c. the snow period (50 days in duration) is the shortest in the transcarpathian lowland. the annual precipitation is 650 mm (lipinski, 2003 ). the area lies within the forest-steppe vegetational belt of the pannonsky geobotanical province of heliophilous nemoral forests, meadows and meadow steppe (barabich, 1977). an important characteristic of these forests is the presence of an admixture of the southern species of oak (querus petraea and q. dalechampii). the forests also include carpinus betulus, 42 yurchenko t. acer campestre, ulmus glabra, rarely fagus sylvatica. fraxinus excelsior grows at lower altitudes, and swampy areas are occupied by alnus glutinosa. the understory is formed by corylus avellana, crataegus sp., euonymus verrucosa, e. europaeus, frangula alnus, viburnum opulus, sambucus nigra, and prunus spinosa. the ground cover is dominated by carex brizoides, galium odoratum, elymus repens, poa palustris, festuca pratensis, viola odorata, and convallaria majalis. the late pleistocene vegetational evolution in the transcarpathian lowland has been studied since the 70s of the xx century. the location of the studied sites is shown in fig. 1. the first pollen research has been carried out for the upper paleolithic site molochny kamin’, situated in a cave at the foothills of the carpathian mountains (gladilin & pashkevich, 1977; pashkevich, 1984). it has been shown that during the würm, the lower boundary of the mountain belt of alpine and subalpine meadows was located topographically at lower elevations than nowadays. sparse forest (pinus sylvestris, larix and juniperus) with ferns in the ground cover spread on the adjacent lowlands. a pollen study has been also carried out at the multilayered archeological site koroleve located on the highest terrace of the tysa river (pashkevich, 1984; adamenko & grodetskaya, 1987). four stages of vegetational evolution during the late pleistocene have been established: 1) pine and oak-pine forests (the transition from saalian to the last interglacial); 2) forests of pinus sylvestris, p. cembra, picea and larix with an admixture of quercus, fagus sylvatica, and alnus (beginning of the last interglacial, the kaydaky time); 3) quercus-carpinus and quercus-fagus forests with an admixture of pinus sylvestris and picea (last interglacial optimum, the pryluky time); 4) picea forest in the mountains, quercus and pinus sylvestris forests in the lowlands (the vytachiv time). during the last decade, a pollen study has been carried out for the gat’ site, located on the flat plain in the centre of the transcarpathian lowland (gerasimenko, 2006), and the paleolithic site sokyrnytsya i, situated on the high terrace of the tysa river, closer to the foothills of the carpathian mountains (gerasimenko, 2011). stages and phases of the vegetational evolution during the late pleistocene have been shown for the last interglacial (kaydaky unit), fig.1 location map of the studied sites. 43 vegetational evolution in the transcarpathian lowland ... beregovo i site early glacial (tyasmyn and pryluky units), and the pleniglacial (uday, vytachiv and bug units). the following stages of the last interglacial vegetation development have been recognized: pre-temperate (pine forest with an admixture of broad-leaved trees), earlytemperate (quercetum mixtum), the climatic optimum (broad-leaved forest with a high share of carpinus betulus and corylus), late-temperate (mixed forest: carpinus betulus, abies and picea), and post-temperate (piceapinus forest). during the two early glacial stadials, arcto -alpine and arcto-subalpine meadow-steppe and meadow-forest spread. during the first early glacial interstadial, mixed forest from boreal and broad-leaved trees existed, whereas during the second interstadial, boreal forest-meadow occupied the area. during the early pleniglacial (the uday time), arcto-alpine meadow and meadow-steppe expanded there. birch-pine forest with a small admixture of broad-leaved trees existed during the middle pleniglacial (the vytachiv time). the late pleniglacial (the bug time) was characterized by a spread of subperiglacial meadows and meadowsteppes. despite the importance of the information obtained in the previous study, further investigation is necessary in order to reconstruct in details the different vegetational patterns in the transcarpathian lowland and to define short-period phases in the vegetational development, particularly during the middle pleniglacial. such an important palaeobotanical issue is still unclear, as well as the existence of refugia of broad-leaved vegetation during the pleniglacial. 2. site location and stratigraphy the beregovo і site is located 1 km south of the beregovo town, on the 3rd terrace of the tysa river (1520 m above the floodplain level), in a place where the terrace is cut by the valley of the tysa tributary the werke river. the archeological study of the upper palaeolithic site beregovo i started in the 70-80s of the last century (smirnov, 1974; gladilin & soldatenko, 1975; tkachenko, 1989, 2003), as well as its pedostratigraphical study (adamenko et al. 1981; adamenko & grodetskaya, 1987). four upper pleistocene palaeosols were found and characterized within the loess cover of the terrace. the lowermost palaeosol was correlated with the last interglacial. the cultural layer corresponds to the loess unit separating the 1st and 2nd palaeosols, and it was related to the upper paleolithic (the late aurignacian). a recent research (usik, 2008, 2011) shows that the early aurignacian industry of the kremsdoufur type is represented there. the chronology of the sites has been based on the quaternary stratigraphical framework of ukraine (veklitch, 1993). later studies (matviishyna at al., 2010) proved that the uday loess unit is correlated with the early pleniglacial, the vytachiv unit with the middle pleniglacial, and the bug unit corresponds to the late pleniglacial. the vytachiv unit is subdivided into subunits which are correlated with the middle pleniglacial of western europe in the following way (gerasimenko, 2004): the lower vytachiv soil unit (vt1) corresponds to the interstadials moershoofd and hengelo, the middle vytachiv loess unit (vt2) is correlated with the huneborg stadial, and the upper vytachiv soil uit (vt3) corresponds to the denecamp interstadial. a short description of the upper part of the section, which was also studied palynologically (gerasimenko, 2006), is provided below. 0.00-0.20 m the former archaeological tip; 0.20-1.30 m the holocene (hl) luvisol; 1.30-1.85 m bug loess unit (bg) loess, pale yellowishbrow, clayey loam; 1.85-3.10 m vytachiv palaeosol unit (vt) with subunits: 1.85-2.00 m vt3c incipient soil, light-brown, clayey, compacted, with prismatic structure; 2.00-2.40 m vt3b upper cambisol, dark-brown, clayey, compacted, with prismatic structure and a lot of charcoal. the ams 14c date 27/26,6 ka uncal bp has been obtained on charcoal from the depth 2.08 2.18 m (usik at al., 2014); 2.40-2.60 m vt3b/vt2 transitional horizon of the lower cambisol, formed in the loess-like deposits, lightbrown, less clayey, slightly compacted, with small spots of ochre and charcoal. the aurignacian artifacts have been found here, mainly at the depth 2.402.50 m. 2.60-3.10 m vt1 lower cambisol, bright-brown, clayey, prismatic, strongly compacted, with clay cutans on ped surfaces, the downward transition is gradual; 3.10-3.50 m uday loess unit (ud) loess-like loam, gleyey, light greenish-grey, clayey loam, blocky, much less compacted than the overlying soil, with tiny nodules and punctuation of manganese hydroxides, particularly at the upper layer. 3. methods pollen was extracted from the sediments with the following procedure: a sample (100 g in weight) is boiled in a 10% solution of hcl, washed out with distilled water to neutral reaction, boiled in 25% solution of na4p2o7, and washed out again to neutral reaction. a second treatment in a 10% solution of hcl is undertaken in order to remove secondary carbonates, the sample washed out, and, finally, boiled in a 10% solution of koh with the consequent washing out to neutral reaction. after maceration, the sample is centrifuged in distilled water and heavy liquid (cdi2+ki). a heavy liquid of densities between 2.2 and 2.0 g/cm3 is used, and the obtained material is washed out several times (with the removal of water above the residue) until its volume fits a lab tube. then the residue is treated in a cold 45% solution of hf for 24 hours. such a treatment enables to obtain not less than 200 grains of pollen and terrestrial spores from a sample of mineral deposits. the preservation of palynomorphs in the studied samples was good. non-pollen palynomorphs (npp) are also represented, though they are not numerous in the studied samples. palynological atlases (bobrov et al., 1983; kuprianova & alyoshina, 1972, 1978; reille, 1998) have been used for pollen identification. the program psimpoll 4.27 (bennett, 2009) has been used to plot the pollen diagram. percentages of arboreal and non-arboreal pollen (ap and nap, respectively) and spores have been counted from a total sum including all of them. npp were represented mainly by pseudoschizaea, which is an indicator of local humidity in soils (scott, 1992). they are shown in a separate graph of the pollen diagram. 4. results eight pollen samples, labelled with the site prefix b, have been analyzed from the deposits of the beregovo i site (fig. 2). vegetation types are determined according to the results of the fundamental empirical studies of surface pollen samples in eastern europe (grichuk, 1989). b-1, corresponds to the upper part of uday loess unit (ud) and it records a forest-meadow vegetation (ap 44%, nap 8%, and spores 48%). the ap includes mainly pinus sylvestris (23%), betula (13%), and alnus (4%) though broad-leaved taxa are also represented (tilia cordata, 3%, and ulmus sp., 1%). the nap consists of forbs (5%) and poaceae (3%). the former includes asteroideae (2%) and single pollen grains of fabaceae, dipsacaceae and rumex. lycopodiaceae (38%) dominate among the spores. the percentage of bryales is 9%, and only single spores of filicales monolete occur. b-2, corresponds to the lower part of the lower vytachiv (vt1) soil. the pollen spectrum reveals a foreststeppe (ар 62.0%, nap 21.0%, and spores 17.0%). pinus sylvestris pollen prevails in the ap (36.6%), and pollen of picea abies is noticeable (8.5%). the pollen share of broad-leaved trees increases significantly as compared to b-1: quercus robur (4.2%), ulmus sp. (2.8%), carpinus betulus and fagus sylvatica (each being 1.4%). on the contrary, the pollen percentages of parvifoliate hardwood decrease, including betula (1.4%) and alnus (4.0%). pollen of sambucus nigra occurs in small numbers (1.4%). forbs prevail in the nap (17%), and they consist of asteraceae (5.6%), rosaceae (4.2%), including filipendula, and single pollen grains of scrophulariaceae, ranunculaceae, brassicaceae, and fabaceae. the rest of the nap consists of chenopodiaceae (2.8%) and few poaceae (1.4%). the pollen percentages of lycopodiaceae significantly decrease (14.4%). spores of sphagnum and filicales monolete (each being 1.4%) are present, and glomus-type spores, as well as pseudoschizaea spores also occur. b-3, in the upper part of the soil vt1, reveals a forest type of pollen spectrum (ар 46.9%, nap 29.2%, spores 23.8%). pollen percentages of pinus sylvestris and picea abies decrease (22.3% and 3.8%, respectively). on the contrary, pollen percentages of broadleaved trees significantly increase: quercus robur (4.6%), ulmus sp. and carpinus betulus (each being 1.4%). single pollen grains of caprifoliaceae and cornus mas occur. parvifoliate hardwood is represented by betula (5.4%) and alnus (3.1%). forbs prevail in the nap (18.5%). pollen of asteroideae is abundant (6.2%), cichorioideae and plantaginaceae are noticeable (3.83.1%), and single pollen grains of caryophyllaceae, ------------------------ >>> fig.2 pollen percentage diagram from the paleolithic site beregovo i. 44 yurchenko t. rosaceae including filipendula, scrophulariaceae, and fabaceae occur. pollen percentages of herbal xerophytes increase (chenopodiaceae, 9.2%). pollen of hydrophytes (typhaceae) also occur. the spores are represented by lycopodiaceae (16.2%), bryales (4.6%), sphagnum (2.3%), and filicales monolete (0.8%). the number of glomus-type spores and pseudoschizaea increases. b-4, in the loess unit vt2, has a forest-meadow type of pollen spectrum: ар 31.4%, nap 27.5%, spores 41.2%. in the ap, pinus sylvestris prevails (20.6%). betula sp. (7.8%) and picea abies (1.9%) are well represented. one pollen grain of tilia cordata has been found. forbs prevails in the nap (15.7%) and consists of asteraceae (7.8%), ranunculaceae (3.9%), polygonaceae (1.9%), fabaceae and caryophyllaceae (being 0.9% each). pollen percentage of poaceae is low (1.9%), as well as cyperaceae and liliaceae (being 0.9% each). pollen of herbal xerophytes include chenopodiaceae (6.8%) and ephedra (0.9%). the spores are represented by lycopodiaceae (29.4%) which prevail over those of bryales (11.7%). the numbers of glomustype spores and pseudoschizaea spores further increase, and abundant microcharcoal is present. three pollen samples correspond to the upper vytachiv soil (vt3b). b-5 corresponds to the lower part of the soil vt3b and has a forest-meadow type of pollen spectrum (ар 29.0%, nap 39.3%, spores 31.8%). pinus sylvestris (17.8%) prevails in the ap, and only a few pollen grains of picea abies (1.9%) are present. single pollen grains of broad-leaved taxa (quercus robur, tilia cordata and corylus avellana) occur. the parvifoliate hardwood is represented by betula (4.7%) and alnus (1.9%). forbs prevail in the nap (18.7%), but the percentage of poaceae is quite noticeable (7.5%). among forbs, pollen of asteraceae is abundant (7.5%), rosaceae (including filipendula) and ranunculaceae (including thalictrum) are noticeable (being 4.4% each), whereas polygonaceae is poorly represented (1.9%), and only single pollen grains of lamiaceae, fabaceae, linaceae, and hypericum have been found. the pollen percentages of xerophytes increase, including chenopodiaceae (10.3%) and artemisia (1.9%). the spores include mainly lycopodiaceae (29.4%) and few bryales (2.8%). the number of glomus-type spores and pseudoschizaea spores further increases, and microcharcoal is abundant. b-6, corresponds to the upper part of the soil vt3b, and it also has a forest-meadow type of pollen spectrum (ар 38.1%, nap 22.9%, spores 39.0). pinus sylvestris prevails in the ap (21.9%), and pollen of picea abies (3.8%), betula (2.9%) and alnus (1.0%) are present. the pollen percentages of broad-leaved taxa increase: tilia cordata (4.8%) and carpinus betulus (2.9%). one grain of viburnum opulus is present. forbs prevail in the nap (14.3%), whereas pollen percentage of poaceae is small (2.9%). the forbs include pollen of asteraceae (7.6%), scrophulariaceae and rosaceae (each being 1.9%) and single pollen grains of polygonaceae, apiaceae and cichorioideae. the pollen percentages of xerophytes decrease (chenopodiaceae 2.9%). pollen of hydrophytes (nymphaеаceae and sparganiaceae) appears. the pollen percentage of lycopodiaceae is large (24.8%), spores of filicales monolete and bryales are noticeable (being 6.7% each), and spores of sphagnum occur rarely (2.5%). the numbers of glomus-type spores and pseudoschizaea spores are rather large. b-7, corresponds to the transition to the soil vt3c and has a forest type of pollen spectrum (ар 52.4%, nap 26.2%, spores 21.4%). pinus sylvestris prevails in the ap (21.4%), and pollen of picea abies (3.6%) is present. broad-leaved taxa are represented by pollen of carpinus betulus (7.1%) and ulmus sp. (3.6%). the pollen percentages of parvifoliate hardwood are large (betula 13.1% and alnus 3.6%). the nap consists of forbs: asteraceae (4.8%), ranunculaceae and plantaginaceae (being 2.4% each), scrophulariaceae, linaceae and primulaceae (being 1.2% each). only few pollen grains of chenopodiaceae have been found. pollen of hydrophytes appear: potamogetonaceae (2.4%), butomaceae and nymphaеаceae (being 1.0% each). lycopodiaceae prevail among the spores (10.7%). spores of filicales monolete (4.8%), sphagnum (2.4%) osmunda, bryales and filicales trilete (being 1.2% each) have been also found. there are abundant microcharcoal particles, glomus-type spores and pseudoschizaea spores. the lower part of the bug loess unit (bg) has a meadow-steppe type of pollen spectrum (b-8): ар 25%, nap 21%, spores 54%. the ap includes mainly pinus sylvestris (17.0%). pollen of picea abies is present (3.0%) and single grains of carpinus betulus and ulmus sp. have been found. pollen percentages of other trees are also small: alnus (3%) and salix (1.0%). the pollen of forbs (11.5%) consist of asteraceae (4.0%), linaceae (2.0%), and single grains of brassicaceae, ranunculaceae, scrophulariaceae, fabaceae, lamiaceae, caryophyllaceae, dipsacaceae, and cichorioideae. thus, this sample is very diverse in its composition. herbal xerophytes are represented by chenopodiaceaе (6.0%). spores consist of lycopodiaceae (23.0%), filicales monolete (17.0%) and bryales (13.0%). one spore of sphagnum has been found. the numbers of microcharcoal, glomus-type spores and pseudoschizaea spores are still large. 5. palaeoenvironment the correspondence of pollen surface samples to the modern vegetational composition (grichuk, 1989) has been used here to reconstruct the phases of vegetational evolution during the vytachiv time (the middle pleniglacial), the end of the preceding uday time (the early pleniglacial) and the beginning of the following bug time (the late pleniglacial). before the beginning of the middle pleniglacial (the end of the uday time), forest-meadow ecosystems existed (b-1). club-mosses and green mosses formed the ground cover of birch-pine forests. occurrence of pollen grains of ulmus sp. and tilia cordata indicate a possible existence of refugia of broad-leaved vegetation in the valleys. alder groves grew in the wet localities. meadows consisted of plants from asteraceae, fabaceae, dipsacaceae, and poaceae fami 45 vegetational evolution in the transcarpathian lowland ... beregovo i site lies. this type of vegetation is typical for a cool and humid boreal climate, that corresponds to the end of a stadial. during the first stage of the middle pleniglacial (the early vytachiv time, vt1), two phases of vegetation development have been recognized. during the first phase, coniferous and broad-leaved forests occupied the area under investigation. elm-oak forests with an admixture of hornbeam, beech and spruce grew on the fertile loamy soils, pine groves occupied sand terraces and alder occurred near the river courses. mesophytic herbs of the asteraceae, rosaceae, brassicaceae and fabaceae families grew in the ground layer of broadleaved forests. the spread of broad-leaved trees indicates an interstadial warming. the replacement of clubmosses and mosses by herbs in the ground cover of forests might be connected with an increase in evaporation under a warmer climate, and, thus, with a decrease in ground moisture. the second phase of vegetation evolution was characterized by a spread of a forest-steppe, as it is evidenced by the decrease in the ap and the spore percentages in b-3. broad-leaved taxa included oak, hornbeam and lime-tree. the portion of wet-loving beech and spruce in the forest composition decreased as compared with the preceding phase. this, as well as the spread of herbal associations, indicates that the climate became less humid than during the preceding phase. though it was rather warm, as suggested by the pollen percentages of broad-leaved taxa and the appearance of cornus mas pollen. open areas were occupied by meadow-steppe: mainly plants belonging to asteroideae, cichorioideae and plantaginaceae, less frequently caryophyllaceae, rosaceae (including filipendula) scrophulariaceae, and fabaceae. the appearance of chenopodiaceae pollen indicates the replacement of meadows by meadow-steppe. nevertheless, the abundance of pseudoschizaea spores and pollen of typha latifolia indicate a local increase in the ground moisture, connected with a higher water level in the river (scott, 1992). the second stage of the middle pleniglacial (the middle vytachiv time, vt2) was characterized by the spread of a forest-meadow vegetation (b-4). a reduction in forest areas occurred. forests consisted mainly of birch and pine, and the portion of broadleaved trees decreased as compared to the previous stage. this indicates a significant cooling, that is typical for a stadial. however, few refugia of broad-leaved trees still existed, and lime-tree evidently continued to produce pollen. the low pollen percentages of pine indicate that its portion in the arboreal vegetation was very small. mesophytic plants from the asteraceae, ranunculaceae, polygonaceae, fabaceae and caryophyllaceae families prevailed in the open ecosystems, whereas steppe components of herbal coenoses (chenopodiaceae and sparse ephedra) were less frequent than during the previous phase. the decrease in warmth and evaporation was a possible reason for the spread of meadows to the expenses of meadow-steppe. the composition of forbs became more diverse, and club-mosess, mosses and microspores (indicators of soil humidity) were abundant. it was a time when the carriers of the aurignacian industry arrived at the site. the third stage of the middle pleniglacial (the late vytachiv time, vt3) was characterized by three phases of vegetation development. during the first phase, there existed a forest-steppe vegetation (b-5). the low pollen percentages of pine and spruce indicate that they did not grow near the site (their pollen was probably wind-transported from the carpathian mountains). birch forests with club-mosses and green mosses in the ground cover prevailed, and alder grew in the lowest localities. oak, lime-tree and hazel occurred rarely. the portion of broad-leaved trees slightly increased as compared to the vt2 time, but climate still was cool and corresponded to a transition from a stadial to an interstadial. herbal associations were of a meadow-steppe type. forbs prevailed, and their composition became more diverse than before, including plants of the asteraceae, rosaceae, ranunculaceae (including thalictrum), polygonaceae, lamiaceae, fabaceae, linaceae families and hypericum. the steppe elements included poaceae, chenopodiaceae and artemisia. the second phase of vegetation evolution (b-6) was characterized by a spread of the forest-meadow vegetation. forest areas became larger, and the participation of broad-leaved trees, represented by limetree and hornbeam, increased, as well as the spread of ferns in the ground cover. spruce became more abundant, and viburnum opulus occurred in the undergrowth. this phase corresponds to an interstadial warming. meadows included mesophytic herbs from asteroideae, scrophulariaceae, polygonaceae, apiaceae and cichorioideae. the portion of grasses and xerophytes significantly decreased. wet localities were occupied by alder, club-mosses and green mosses. the increase in pollen of hydrophytes (nymphaеаceae and sparganiaceae) and pseudoschizaea spores indicates a local raise in the water level. the third phase of vegetation evolution (b-7) was characterized by a spread of elm-hornbeam forest with admixture of spruce on fertile loamy soils and pinebirch forest on sandy terraces. a spread of wet-loving hornbeam and spruce was maximum as compared with the previous phases. this indicates a further increase in humidity during the interstadial, ams dated to 27/26.6 ka uncal bp (usik at al., 2014). the ground cover of broad-leaved forests consisted of ferns and mesophytic herbs from asteraceae, ranunculaceae, plantaginaceae, scrophulariaceae, linaceae, and primulaceae families. pine-birch and alder groves had club mosses and green mosses in the ground cover. the presence of hydrophytes (potamogetonaceae, butomaceae, nymphaеаceae and osmunda), as well as pseudoschizaea spores indicate a high-water level in the river. after the end of the middle pleniglacial (the beginning of the bug time), there occurred a spread of meadow vegetation (b-8). the arboreal vegetation 46 yurchenko t. grew along the river course and consisted of spruce, alder and willow. the low pollen percentages of pine indicate a very limited growth of this tree in the studied area. the presence of few pollen grains of elm and hornbeam shows that their refugia still existed in the transcarpathian lowland. club-mosses, green mosses and ferns formed the ground cover under the trees, but they could also grow in the meadows. the maximum of pseudoschizaea spores shows an excess of water in the ground. meadow plants were diverse (asteroideae, linaceae, brassicaceae, ranunculaceae, scrophulariaceae, fabaceae, lamiaceae, caryophyllaceae, dipsacaceae and cichorioideae). the strong reduction in forested areas and the significant decrease in broadleaved taxa indicate that the climate became much colder than before. it was the beginning of a stadial. 6. discussion in general, the fulfilled reconstructions are correlated with those obtained from the other sites of the transcarpathia but the local characteristics of the vegetation on different forms of relief are rather distinct. during the uday time (the early pleniglacial) on the high river terraces, grasses and sedges dominated, and few alder, willow and pine occurred in gullies. at the end of this time, trees disappeared completely (gladilin & pashkevich, 1977; pashkevich, 1984). a spread of cryophytes (shrub birch and arcto-boreal forms of clubmosses) during this time (gerasimenko, 2006) is an indicator of a periglacial climate. thus, refugia of arboreal and broad-leaved trees existed only on the slopes of the low river terraces as in the case of the beregovo i site. in western ukraine, the complete successions of the vytachiv deposits (the middle pleniglacial) are represented only in the middle dniester valley (bolikhovskaya, pashkevich, 1982; bolikhovskaya, 1995) and at the beregovo i site. the first stage of the middle pleniglacial (the vt1 time) is correlated by 14c dating with the two first interstadials of the middle valday (gerasimenko, 2004). during the warmest interstadial (39-37 kyr bp), the forest-steppe (with admixture of quercus robur, carpinus betulus, tilia cordata and ulmus sp. in pine forest) was distributed on the low terraces of the dniester river. on the low terraces of the tysa river, the forests included more broad-leaved taxa, and mesophytic trees such as fagus sylvatica and picea abies, as well as the warm-loving cornus mas. during the second stage of the middle pleniglacial (the vt2 time, 14c 36-30 kyr bp) which is correlated with the second middle valday stadial (gerasimenko, 2004), the middle dniester valley was occupied by periglacial vegetation. shrub associations of betula fruticosa, b. nana and alnaster fruticosus on sphagnum peat bogs, on one hand, and xeric herbs, on the other hand, formed a mosaic vegetational pattern (bolikhovskaya, 1995). during this time on the lower terraces of the tysa river, forested areas became much smaller than during the preceding interstadial, but tilia cordata persisted, and herbal cover consisted mainly of mesophytes. there are no indications of the presence of cryophytes. during the third stage of the middle pleniglacial (the vt3 time, 14c 30-27 kyr bp), which is correlated with the third middle valdai interstadial (14c 29-25 kyr bp), carpinus betulus was a main component of the forests of the middle dniester valley. fagus sylvatica, quercus robur, tilia platyphyllos, acer and fraxinus also lived there (bolikhovskaya, pashkevich, 1984; bolikhovskaya, 1995). on the lower terraces of the tysa river, during the climatic optimum of the late vytachiv time, carpinus betulus also prevailed among broadleaved trees, but the portion of meso-hygrophytic betula pubescens was significant. the latter is evidently connected with a rise of water level in the river, indicated by the spread of hydrophytes and abundance of pseudoschizaea in the soils. thus, during the correlative stages of the middle pleniglacial, the vegetation of the low river terraces in transcarpathia was formed under more humid and warmer climate than in the middle dniester valley, although during the third phase, the lower river terraces of transcarpathia were over-wetted as compared with the dniester terraces. the vegetation of the vytachiv time around the other transcarpathian site, located in the low landform, also included abundant hygrophytes (gerasimenko, 2011). alnus glutinosa and cyperaceae were abundant, though oak was common in the forest composition. on the contrary, on the high terraces of the tysa river, oak formed a small admixture in light pine forests with herbal ground cover. the portion of wet-loving ferns and club-mosses was lower than at the beregovo i site (pashkevich, 1984; gerasimenko, 2006). thus, during the vytachiv time, the vegetation of the low terraces was richer in mesophytic and hygrophytic components than in the higher levels of the relief. during the late pleniglacial (the bug time), alpine and subalpine meadows including cryophytic plants (alnaster fruticosus, betula nana, botrychium boreale, and lycopodium selago), occupied the foothills of the carpathian mountains, whereas in the gullies that dissected the foothills, pine and larch were growing (pashkevich, 1986). more xeric periglacial meadowsteppe vegetation spread on the high river terraces (gerasimenko, 2006), although at the beginning of the bug time cryophytes were absent in these meadows, which indicates the existence of a less harsh boreal climate. meadow vegetation also dominated on low terraces of the tysa river. here, arboreal vegetation included boreal trees and a few elms and hornbeams. thus, the distribution of cold-tolerant and warmthdemanding plants in transcarpathia was controlled by the elevation. at the beginning of the bug time, broadleaved trees did not grow in the middle dniester valley. as opposite, arcto-alpine plants formed a significant part of the tundra-steppe and tundra-forest-steppe vegetation (bolikhovskaya & pashkevich, 1982; gerasimenko at al., 2012). thus, the climate of the transcarpathian river valleys was essentially milder than in the middle dniester valley. pollen and plant macrofossil evidence indicates that broad-leaved trees grew in the eastern part of the middle danube plain (hungary) even during the lgm (willis at al., 2000). judging from these data, refugia of broad-leaved trees were present 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[the upper paleolithic of ukraine (the sites of the aurignacian tradition)]. kyiv, p.p. 199. (in ukrainian) usik v.i. (2008) verkhniy paleolit zakarpattya: khronologiya i kul'turnaya prinadlezhnost' orin'yaka berehove i. [the upper paleolithic of the transcarpathia: chronology and cultural attribution of the aurignacian at the beregovo і]. materialy i doslidzhennya z arkheologii prykarpattya i volyni, 12, 49-67. (in ukrainian) usik v.i., monihal k., gerasimenko n.p. (2011) verkhniy paleolit zakarpattya. doslidzhennya paleolitychnoyi stoyanky berehove i u 2006 2007 years. [the upper paleolithic of transcarpathia. research paleolithic sites beregovo i in 20062007]. archaeological researches in ukraine (2006-2007), kyiv, 344-350. (in ukrainian) usik v., nigst p., haesaerts p., gerasimenko n., koulakovska l., racz b., kromer b., hublin j.j. (2014) new date of the early upper paleolithic of western ukraine: chronology, environment and human behavior at the aurignacian site beregovo i. xvii congress mondial de l’uispp, burgos, 227-228. vakhrushev b.a., kovalchuk i.p., komlev o.o., kravchuk y.s., palienko e.t., rud'ko g.i., stetsyuk v.v. (2010) relʹyef ukrayiny [relief of ukraine]. publishing house "slovo", kyiv, p.p. 688. (in ukrainian) veklitch m.f. (1993) stratigraficheskaya skhema p l e y s t o t s e n o v y k h o b l o z h e n i y u k r a i n y [stratigraphical framework of quaternary deposits of ukraine]. goskom geologii ukrainy, kiev, 1 40. (in russian) willis k., rudner e., sumegi p. (2000) the full-glacial forests of central and southeastern europe. quaternary research, 203-213. 49 vegetational evolution in the transcarpathian lowland ... beregovo i site ms. received: november 2, 2016 final text received: march 18, 2017 microsoft word 00_indice_lm04.docx il quaternario it issn 039-3356 italian journal of quaternary sciences 24 (1), 2011 131-140 first data on the latest pleistocene mammals from mora cavorso cave (jenne, latium, central italy) leonardo salari1, daria passacantando2 & mario f. rolfo3 1 department of earth sciences, university of rome sapienza, rome 2 department of biological sciences, university of rome tor vergata, rome 3 department of cultural heritage, university of rome tor vergata, rome correspondent author: l. salari <leonardosalari@virgilio.it> abstract: salari l., passacantando d. & rolfo m.f., first data on the latest pleistocene mammals from mora cavorso cave (jenne, latium, central italy). since 2006 the mora cavorso cave has been object of archaeological investigations, and archaeological and faunal finds have been recorded referable, with some discontinuities, to an interval of time lasting over 13,000 years. the most ancient testimonies till now investigated are referable to the terminal phases of the late pleistocene and are followed by various holocene layers between the mesolithic and the middle age. in this paper the preliminary data related to the large mammals, together with the hare and the greats rodents, attributed to the latest pleistocene are described. nine taxa of fossil mammals in the “dig b2” of the room 1 and ascribed to a late upper paleolithic cultural horizon (final epigravettian) have been found: lepus sp., marmota marmota, vulpes vulpes, mustela nivalis, sus scrofa, cervus elaphus, capreolus capreolus, rupicapra sp. and capra ibex. from other places of the cave (the perturbed ground of the room 1 and the “sinkhole”) the fossil remains of lepus sp., lepus corsicanus, castor fiber, m. marmota, canis lupus, ursus arctos, equus ferus, e. hydruntinus, s. scrofa, c. elaphus, c. capreolus and c. ibex have been also found and these too are referable to the latest pleistocene. the marmot and the ibex are the most significant species, but is even important the red deer presence, and a particular attention deserves also european beaver, till now not signaled in lateglacial mammal assemblages of central italy, and the sure evidence of the italic hare. the ecological requirements of the present taxa allow reconstructing the environment of the simbruini mounts and the tall of the aniene river valley during such period colder than today, outlining a composite landscape with forests and woods alternated with grasslands, rocky bands and scree slopes, and wetlands. riassunto: salari l., passacantando d. & rolfo m.f., primi dati sui mammiferi tardopleistocenici della grotta mora cavorso (jenne, lazio, italia centrale). la grotta mora cavorso è oggetto d’indagini archeologiche dal 2006 ed ha restituito reperti archeologici e faunistici che coprono, con qualche discontinuità, un intervallo di tempo di oltre 13.000 anni. le più antiche testimonianze finora indagate sono riferibili alle fasi terminali del pleistocene superiore e sono seguite da vari livelli olocenici compresi tra il mesolitico e il medio evo. nella presente nota sono esposti i dati preliminari relativi ai grandi mammiferi, cui sono stati aggregati la lepre e i grossi roditori, rinvenuti nel “saggio b2” della sala 1 e attribuiti al tardo pleistocene superiore; altri resti di vertebrati tardopleistocenici sono stati recuperati in diversi luoghi della grotta (terreno rimaneggiato della sala1 e “inghiottitoio”). le specie maggiormente significative sono marmotta e stambecco, ma è altresì importante la presenza del cervo e meritano una menzione particolare anche il castoro, finora non segnalato tra le faune tardoglaciali dell’italia centrale, e l’individuazione certa della lepre italica. le esigenze ecologiche dei taxa presenti permettono di ricostruire l’ambiente dei monti simbruini e dell’alta valle dell’aniene durante tale periodo più freddo rispetto ad oggi, delineando un paesaggio composito, con foreste e boschi intervallati da praterie, fasce rocciose e aree a pietraia e zone umide. key words: vertebrates, mammals, late pleistocene, epigravettian, palaeoecology. parole-chiave: vertebrati, mammiferi, pleistocene superiore, epigravettiano, paleoecologia. 1. introduction the cave locally called mora cavorso opens to 720 m a.s.l. in the locality palo montano near jenne (rome, latium, central italy); it leans out on the right slope of the upper aniene river valley inside the simbruini mounts regional natural park (fig. 1a). this karst cavity is carved in the “calcilutiti e calcareniti del conaciano-campaniano” formation (c911/38, upper cretaceous) (damiani et al., 1998). the cave has a succession of rooms and ducts. the room 1 (medium dimensions, about 20 x 10 m) is closed towards outside by a recent stone wall and open directly on the slope, on the bottom it is open a passage that leads to a natural duct with slight slope, partially filled by a recent holocene deposit. at the end of the duct the room 2 opens, the first in the interior (about 6 x 4 m), it is paved by a stalagmite crust and below an archaeological deposit is present. on the north wall a second natural duct starts, horizontal, strongly concretioned, about 20 m length, at the end two paths (upper room and lower room) with anthropological remains open (rolfo et al., 2009; 2010). following the discovery of human bones inside the cave, by the members of “shaka zulu” speleological club of subiaco, the archaeological investigations in the l. salari, d. passacantando & rolfo m.f. 132 cave in 2006 started. the digs initially focused the areas of the neolithic human remains outcrop and subsequently in more stratigraphical digs in the most external rooms to the purpose of investigating the stratigraphical sequence of the deposit (fig. 1b). in particular, in the dig b2 (a trench about 4 x 3 m behind the stone wall, in the eastern sector of the front of room 1), just below a perturbed surface layer, the stratigraphic units 109, 110, 120, 135, 254 and 255 (= “dig b2”) are characterized by a compact reddish-brown silty ground with limestone clasts with sharp edges, where a moderate quantity of lithic artifacts referable to a late upper paleolithic cultural horizon (final epigravettian) and numerous fossil remains of vertebrate animals have been recovered. the calcareous floor of the cave has not yet been reached. in this paper the first data on the large mammals, together with the hare and the greats rodents, recorded in “dig b2” and attributed to the latest pleistocene are presented. other mammal remains referable to the latest pleistocene and that have been also found from the filling of an sinkhole that partially opens on the right side of the entry of the cave (= “sinkhole”) and from the perturbed ground of the room 1 are also described. 2. stratigraphic notes the synthetic stratigraphy of the various areas of the cave shows a variously articulated deposit (fig. 2) that develops from the deepest layer till now investigated, referred to the latest pleistocene, up to the superficial level of historical age (rolfo et al., 2010). the “dig b2” is the most ancient layer investigated with stratigraphical methodology and it has been intercepted in the room 1, below the altered surface layer with micromammal and bird remains and several fossil bones of great wild mammals together with numerous finds of prehistoric and recent domestic mammals. the “dig b2” is a compact reddish-brown silty ground with limestone clasts with sharp edges that vary in diameter from few millimeters to the centimeter, and with a thickness of about 20-30 cm. in this layer many fossil remains of vertebrate have been found together with a moderate number of lithic artifacts referable to final epigravettian, such as a frontal scraper on a retouched blade of jaspered flint, three fragments of backed blade lets, a fragment of backed point and a multiple burin. a radiometric dating1 performed on a marmot mandible from this layer, has provided the age of 13,460±50 years bp (calibrated 14,175 13,910 bc 1σ) and agrees well with the attribution of the “dig b2” lithic artifacts to a final epigravettian cultural horizon. the “sinkole” instead is the filling of a sinkhole that partially opens on the right side of the entry of the cave. this include a pinkish-gray silty sand ground with coarse limestone breccias with sharp edges, and a small level with reddish slimy soil, and there some bone remains of vertebrate referable to the latest pleistocene have been also found. 1 all the radiometric dating have been performed by the “centre de datation par le radiocarbone cnrs”, lyon (france), except that on a mesolithic red deer tooth, performed by the “beta analytic inc.”, miami (u.s.a.). fig. 1 mora cavorso cave: a) location of the site; b) longitudinal section (up) and plan (down) of the cave. grotta mora cavorso: a) ubicazione del sito; b) sezione (in alto) e pianta (in basso) della grotta first data on the latest pleistocene mammals from mora cavorso cave… 133 a layer from the inferior room which can be attributed to early holocene (mesolithic cultural phase) follows; it is rich of cervus elaphus bones in partially articulated (salari et al., 2009; rolfo et al., 2010). also for this level have been made two radiometric dating, one on a red deer tooth (8,770 ± 60 years bp, calibrated 7,950 7,790 bc 1σ), and the other on a charcoal fragment (8,805 ± 45 years bp, calibrated 8,197 7,729 bc 1σ). in this layer, except a moderate number of charcoal fragments and various ashes spots, no other evidence of human presence has been discovered. this level underlies a layer dated to the ancient neolithic characterized by the noticeable presence of abundant human remains referable at least 21 individuals (passacantando, 2009), concerning partly disturbed burials (in the upper and lower room). archaeological finds have also been recovered and are pertinent to the various funeral outfits (rolfo et al., 2009; 2010), together with bones and teeth primarily of domestic fauna, above all ovis vel capra (salari et al., 2009). as well in this case two radiometric dating are been performed, the first one on human bone (6,405 ± 35 years bp, calibrated 5,472 5,314 bc 1σ), the second on a charcoal fragment (6,275 ± 45 years bp, calibrated 5,322 5,084 bc 1σ). a layer from the room 2 (dig c) has to be referred to the neolithic final phase; it is characterized by a level rich of charcoal and ashes. in the deeper part of the room 1 (dig b1) the archaeological sequence is superficially covered by a layer very rich of pottery (fragments and a whole bowl) shed anywhere, and human bones, referable to disturbed burials dated to the middle bronze age (first half of ii millennium bc). rare but noticeable it is the pottery referable to the historical age (viii-x century ad) recovered in the dig a, in the external dig, and on the ground of the upper level of the dig b1 of the room 1 (rolfo et al., 2010). 3. methodology the proceeding of the analyses of the “dig b2” faunal remains, referable to a final epigravettian horizon, were carried on at the same time to archaeological investigations progress. other mammal remains referable to the latest pleistocene have been recovered from the “sinkhole” and from a disturbed level of the room 1. the examined finds have been compared to the osteological material stored in the department of earth sciences of the university of rome “sapienza”. the bone remains are very fragmentary and generally their state of preservation does not allow the individualization of the anatomical portion, neither the taxonomic determination. among the determined remains, nevertheless, there are also some intact skeletal elements like metapodials, carpal and tarsal bones, phalanges, isolated teeth and some mandibles. this material has been recovered in different places of the cave, so its description will be carried on taking into account the origin place of the remains. the mammal bones recovered in the “dig b2” originate from a level investigated with stratigraphical methodology, it is well dated both radiometrically and according to the cultural chronology and it is therefore possible to effect a numerical analysis. every taxon is quantified both in number of remains (nr) and in the minimum number of individuals (mni), calculated according bökönyi (1970); the fragments of ribs and vertebrae of difficult taxonomical attribution have been counted apart. for the material remainder, instead are listed out the recognized taxa and valued their relative frequency (tab. 1). 4. faunal description 4.1. the mammals remains from the “dig b2” from the “dig b2” over 1000 mammal remains have been recorded, 171 of which (17.05%) have been anatomically and taxonomically determined. from the fig. 2 mora cavorso cave: stratigraphic synthesis. grotta mora cavorso: stratigrafia sintetica. l. salari, d. passacantando & m.f. rolfo 134 tab. 1, in which the percentages of each taxon are calculated on the total of the determined fragments, while the percentages related to the ribs, to the vertebrae, to the undetermined and to the total determined remains are calculated on the general total, the most abundant taxon is marmota marmota (linnaeus, 1758), with more than the half of the determined remains and a third of the individuals. cervus elaphus linnaeus, 1758, capra ibex linnaeus, 1758, rupicapra sp. and lepus sp. are present with a certain number of fragments, sus scrofa. linnaeus, 1758, capreolus capreolus (linnaeus, 1758) and vulpes vulpes (linnaeus, 1758) with few finds, and mustela nivalis linnaeus, 1766 has present only a single fragment of mandible (fig. 3, n). these finds are accompanied by several birds bones, few amphibious bones and abundant micromammal remains above all rodents, particularly arvicola amphibius (linnaeus, 1758), apodemus sp. and small arvicolids, and scarce bats, rhinolophus ferrumequinum (schreber, 1774) and myotis bechsteinii (kuhl, 1817). the marmot is represented by bones of the whole skeleton (fig. 3, b-d), primarily mandible mainly fragmentary, isolated teeth, phalanges, metapodials and tarsal bones intact, while the skull and the other postcranial skeleton elements are fragmented. this fossil material is referable to at least 7 individuals; some deciduous teeth, a tibia with epiphysis not fused and a very small astragalus point out that among these at least one is a cub. the hare is present with some isolated teeth, metapodials and phalanges than at least two individuals; the scarcity of diagnostic morphological characters (see palacios, 1996) does not allowed a sure attribution of such finds to lepus europaeus pallas, 1778 or lepus corsicanus de winton, 1808. the fox is present with some metapodials and calcaneum (fig. 3, l) of an adult. the wild boar is present with an inferior molar, a third metacarpus (fig. 4, d), a metapodial with distal epiphysis not fused, a carpal bone and a first lateral phalanx concerning a fully grown and a young individual. the red deer is represented by isolated teeth, humerus, femur, tibia (fig. 4, i), carpal and tarsal bones, phalanges (some with the proximal epiphysis not fused) and sesamoids belonging a fully grown and a young individual. the roe deer is present with a mandibular branch fragment, some isolated teeth, two of which deciduous, and a phalanx referable to a young individual and an adult. the ibex is represented by isolated teeth, some of which deciduous, radius, coxal, femur, metapodials with distal epiphysis not fused (fig. 4, f-g), tarsal bones and phalanges referable to a young individual and an adult. the chamois is present with isolated teeth, some of which deciduous, radius (fig. 4, m), ulna and phalanges concerning a fully grown and a young individual; the fragmentary of the finds and particularly the absence of cranial parts with horn cores, useful to the distinction between rupicapra rupicapra (linnaeus, 1758) and rupicapra pyrenaica bonaparte, 1845 (see masini & lovari, 1988), allow to identifying the chamois only to the genus level. the presence of the lithic artifacts and the same mammal assemblage, characterized essentially by ungulate and marmot, would suggest an anthropic contribution of the bone accumulation, but till now only an undetermined fragment with a lithic tool incision has been observed. some bones show traces of gnawing of rodents, while neither signs of carnivores or further traces of human activity are present. considering also the large number of small animals and young individuals among the ungulate ones, it cannot be excluded that, over the humans, also the raptor birds and/or the other factors have contributed to the accumulation of the “dig b2” bones. taxon “dig b2” “sin kh ole” per tur bed n r m n i freq. freq. n. % n. % lepus sp. hare 11 6.43 2 9.52 r r lepus corsicanus italic hare rr castor fiber european beaver rr marmota marmota marmot 94 54.97 7 33.33 a ca canis lupus wolf c vulpes vulpes fox 4 2.34 1 4.76 ursus arctos brown bear cr mustela nivalis weasel 1 0.58 1 4.76 equus ferus rr equus hydruntinus c sus scrofa wild boar 5 2.92 2 9.52 rr cervus elaphus red deer 25 14.62 2 9.52 r ca capreolus capreolus roe deer 4 2.34 2 9.52 r capra ibex ibex 16 9.36 2 9.52 c c rupicapra sp. chamois 11 6.43 2 9.52 total determined 171 17.05 21 ribs 136 13.56 vertebrae 36 3.59 undetermined 660 65.80 total 1003 tab. 1 mora cavorso cave, late pleistocene: number of remains (nr), minimum number of individuals (mni) and percentages (%) from the “dig b2”, and mammal remains frequency (freq.) from the other archaeological contexts (“sinkhole” and the perturbed ground of the room 1); rr: very rare; r: rare; cr: common-rare; c: common; ca: common-abundant; a: abundant. grotta mora cavorso, pleistocene superiore: numero dei resti faunistici (nr), numero minimo degli individui (mni) e relative percentuali (%) del “saggio b2”, e frequenze dei resti faunistici (freq.) relative agli altri contesti archeologici (“inghiottitoio” e terreno rimaneggiato della sala 1); rr: rarissimo; r: raro; cr: comune-raro; c: comune; ca: comune-abbondante; a: abbondante first data on the latest pleistocene mammals from mora cavorso cave… 135 fig. 3 mora cavorso cave, late pleistocene: lepus corsicanus, a) skull; marmota marmota, b) maxilla, c) calcaneum; d1) mandible, lingual view, d2) mandible, labial view; castor fiber, e) mandible, f) skull fragment; ursus arctos, g) upper canine, h) lower canine, i) second lower molar; vulpes vulpes, l) calcaneum; canis lupus, m) mandible; (scale bar: 5 cm); mustela nivalis, n) mandible (scale bar: 2 cm). grotta mora cavorso, pleistocene superiore: lepus corsicanus, a) cranio; marmota marmota, b) mascellare, c) calcagno; d1) mandibola, norma linguale, d2) mandibola, norma labiale; castor fiber, e) mandibola, f) frammento di cranio; ursus arctos, g) canino superiore, h) canino inferiore, i) secondo molare inferiore; vulpes vulpes, l) calcagno; canis lupus, m) mandibola; (riferimento metrico: 5 cm); mustela nivalis, n) mandibola (riferimento metrico: 2 cm). l. salari, d. passacantando & m.f. rolfo 136   fig. 4 mora cavorso cave, late pleistocene: equus ferus, a) first phalanx; equus hydruntinus, b) first phalanx, c) astragalus; sus scrofa, d) third metacarpus; capra ibex, e) metacarpus, f) metacarpus (juvenis); g) metatarsus (juvenis); cervus elaphus, h) metatarsus, i) tibia; capreolus capreolus, l) metatarsus; rupicapra sp., m) radius; (scale bar: 5 cm). grotta mora cavorso, pleistocene superiore: equus ferus, a) prima falange; equus hydruntinus, b) prima falange, c) astragalo; sus scrofa, d) terzo metacarpo; capra ibex, e) metacarpo, f) metacarpo giovanile; g) metatarso giovanile; cervus elaphus, h) metatarso, i) tibia; capreolus capreolus, l) metatarso; rupicapra sp., m) radio; (riferimento metrico: 5 cm). first data on the latest pleistocene mammals from mora cavorso cave… 137 4.2. the mammals remains from the other archaeological contexts from a partially perturbed layer of the room 1 a thousand of vertebrate remains has been recovered in an advanced state of fossilization together with prehistoric and recent domestic mammals. small and mediumsized birds are present, micromammals (a. amphibius, apodemus sp. and small arvicolids), and bones and teeth attributed to hare, marmot, wolf (fig. 3, m), red deer (fig. 4, h), roe deer (fig. 4, l) and ibex (fig. 4, e) (rolfo et al., 2009; salari et al., 2009). some morphological features of a sub-intact skull of hare (fig. 3, a), particularly the occlusal surface contour of p2 with the postcone protrudes further than the lagicone (see palacios, 1996), allow attributing this find to l. corsicanus. in the “sinkhole” a hundred of vertebrate fossil remains chaotically assembled has been recovered, partly from a level characterized by a reddish slimy soil. the bones accumulation seems of reasonable natural contribution (water energy), nevertheless the emptying has not been completed yet, but till now lithic artifacts has not been recovered yet. the mandibles and the skull fragments of m. marmota are abundant and are accompanied by carpal and tarsal bones and phalanges of equus hydruntinus regalia, 1907 (fig. 4, b-c), isolated teeth, metatarsus and phalanges of c. ibex and isolated teeth of ursus arctos linnaeus, 1758 (fig. 3, g-i). there are also rare fragments of birds bones, micromammals and lepus sp., a few isolated teeth of c. elaphus, a skull portion and a mandible2 of castor fiber linnaeus, 1758 (fig. 3, e-f), and a first phalanx of equus ferus boddaert, 1785 (fig. 4, a) and a skull fragment of s. scrofa. 5. chronological and palaeoecological considerations the radiometric dating of 13,460±50 years bp (calibrated 14,175 13,910 bc 1σ) agrees well with the attribution of the “dig b2” lithic industry to a final epigravettian cultural horizon, and permit to attribute this mammal assemblage to the last glacial episode final phases, or rather to the first part of the lateglacial preceding the bølling allerød temperate oscillation (see ravazzi et al., 2007). the lateglacial climatic oscillations recorded in central-western europe also occur in italy, although with less intensity, especially in the mediterranean regions. in the piedmont alpine area, associations with ibex, chamois and marmot during the colder moments are frequent, together with elk, bison and alpine hare, that alternate to red deer and roe deer associations, sometimes accompanied to the wild boar during the temperate moments (petronio et al., 2007; sala, 2007). in mediterranean environment the lateglacial mammal assemblages seem to be conditioned by the geographical location and by the territory morphology at least how the climatic oscillations did. in fact the adriatic slope of the peninsula shows a harder climate than the tyrrhenian one, more temperate and humid. in the adriatic slope prevail associations with e. ferus, e. hydruntinus, chamois and ibex, typical of prevailing opened environments like steppe, prairie and arid mountain; in the tyrrhenian slope, instead, associations with red deer, wild boar and roe deer are present, together with ibex and sometimes to equids, and mark a wider presence of woodland and forest environments (petronio et al., 2007; sala, 2007). the ecological requirements of the taxa from the cave mammal assemblage may therefore provide some useful indications to reconstruct the environmental landscape of the simbruini mounts and of the upper aniene river valley in the late pleistocene final phases and to individualize, if possible, the chronology of the mammal remains recovered from the archaeological contexts others than the “dig b2”. the italic hare is a species adapted to live in different environments, but seems to prefer shrubby dry areas and prairie alternated with hardwood forest with large grassy open clearings; the european hare instead seems to be more connected to the open environments like prairie and steppe, and it is adapted to the traditional agricultural environments, characterized by mixed farming; today the marmot is present in the alps, pyrenees, carpathian and tatra mountains and, recently, has been reintroduced in some areas of the northern apennine and it lives in mountain places characterized by large alpine prairie with stony zone or scattered rock near high stem woods (amori et al., 2008). the european beaver is no longer present in italy since xvi-xvii century (petronio et al., 2007) and today it is present in damp and woodland environments, with streams and stretches of water between france and russia, and the northern balkans and the scandinavian peninsula (halley & rosell, 2002). among the carnivores, both the wolf and the fox are animals adapted to a variety of environments, but generally settle the lair in woodlands with gorges and stony zone; the brown bear is a forest species especially and it prefers environments rich of water; the weasel too prefers open woodland near water (boitani et al., 2003). among artiodactyls the wild boar prefers woods and wetlands, the red deer is particularly common in open woods with large grassy clearings, and the roe deer is a typically woody species and prefer hardwood forests rich of brushwood and clearings; the ibex actually lives on the alps frequenting rocky ledges and alpine prairie, and the chamois frequent coniferous and hardwood woody areas riches of brushwood spaced by rocky walls and stony zones, prairies, bare patches and grassy ledges (boitani et al., 2003). finally e. ferus and e. hydruntinus, were quite commons in the late pleistocene, preferring open environments like steppes and prairies, and their last occurrences in italy are in the early holocene (petronio et al., 2007; conti et al., 2010). the ecological requirements of the taxa discovered in the “dig b2” suggest the presence of woods and forests spaced by prairies, rocky bands and stony zones and wetlands near the site. evidently the faunal finds are been accumulated during a climatic period colder than today, like the presence of species as m. marmota 2 for mere material error, this mandible has been referred to the marmot in the fig. 2 caption of the abstract volume of “convegno in memoria di alberto malatesta (1915-2007) geologo e paleontologo. roma 4-5 febbraio 2010”. we apologize for the mistake. l. salari, d. passacantando & m.f. rolfo 138 and c. ibex shows. both the species were in the lateglacial faunal complex of the central-southern italy, in locality near the sea too, but now they are living in high mountain areas of the alpine arch. however the two species are not considered “cold” stenotherm, but euritherm species (capasso barbato et al., 1991), and nor even the ibex is considered a typical high mountain animal (masseti et al., 1995; phoca cosmetatou 2004). the last palaeontological evidence of m. marmota and c. ibex in centralsouthern italy, however, are referred to the early holocene (petronio et al., 2007), with the rapid climatic warming that characterized the early stages of this epoch, the consequent going up of the tree limit at higher altitude and a considerable reduction of the congenial alpine grasslands type. the distribution of these two species in the peninsula during the last millennia of the late pleistocene was been somewhat unequal. in the adriatic slope the marmot reached salento (southern apulia) (tagliacozzo, 2003), while in the tyrrhenian slope there would not be evidence of its presence at south of the latium. the ibex, frequently with the chamois, instead, is present in the tyrrhenian slope also in southern campania and northern calabria, while there would not be evidence of its presence at south of the gargano promontory (northern apulia) in the adriatic slope (phoca cosmetatou 2004; sala, 2007). the others “dig b2” taxa are currently in central italy and, except the chamois, also in the simbruini mounts area (amori et al., 2009). the faunal remains with an advanced fossilization status recovered in the room 1 together with the prehistoric and recent domestic fauna likely came from the dismantling of “dig b2”, probably because of clandestine excavate or of the arrangement of the cavern as a refuge during the second world war. the faunal assemblage is almost the same to that of the “dig b2” (tab. 1) and may be referred to the same final epigravettian horizon. the mammal remains recovered in the “sinkhole” have some affinities, but also differences compared to the “dig b2” fauna (tab. 1). some taxa (hare, marmot, wild boar, red deer and ibex) are the same and the relatively abundance of m. marmota is also a common element. remains of beaver, brown bear, e. ferus and e. hydruntinus are only in the “sinkhole”. although these are few fossil remains, the presence of the equids, in particular, together to the rare remains of red deer and wild boar, suggest a more opened environment with a less woody covering and perhaps referable to a moment probably cooler than that shown by the “dig b2” mammal fauna. the environments frequented by the total recovered taxa show a composite landscape, in some points not so different to the present, but during moments of climate colder than today. the simbruini mounts slopes were probably covered by deep forests and sparse woods (cervids, carnivores, chamois), spaced by rocky bands and stony ground (ibex, chamois, marmot), while the upper bottom valley were covered by prairies that may evolved in steppe (marmot, hare, equids, ibex) and the river offered banks rich of vegetations, sometimes marshy (wild boars, beaver). 6. comparison with other sites and conclusions in central italy different sites with lateglacial mammal faunas are known, generally associated to epigravettian lithic industry. leaving out the northern tuscany, these sites are placed along the tyrrhenian coast of tuscany and latium (cassoli, 1977; alessio et al., 1993; boscato, 1996; alhaique & di camillo, 2007), along the abruzzi and marche apennine (radmilli, 1977; wilkens, 1991; alhaique & recchi, 2001; 2003; alhaique, 2003; 2005; esu et al., 2006), and the latium inland (radmilli, 1974; pennacchioni & tozzi, 1985; cerilli & brocato, 1998; ucelli gnesutta et al., 2006). among these, some affinities can be noticed with several mammal faunas of the fucino basin in the abruzzi apennine, rather to the latium sites, included the near polesini cave, but this may be attributed to the geographical location and/or to the altimetrical position, than to the eventual chronological correlation with mora cavorso cave. at polesini cave (radmilli, 1974) near tivoli, about 26 km nne of rome, in the lower aniene river valley, the fauna of a sequence that include the recent lateglacial is largely dominated by the red deer, always about 70% among ungulates, followed by wild boar, roe deer and equids with lower rates, while aurochs, chamois and ibex are just present, the marmot and the wolverine sporadically appear. at riparo salvini (alessio et al., 1993; alhaique & di camillo, 2007) near terracina, on the latium tyrrhenian coast, an epigravettian sequence referred to bølling temperate oscillation and that has provided radiometric dating between 12.400 ± 170 and 13.365 ± 190 years bp (14c not-calibrated dating), close to mora cavorso cave dating, the red deer is the more abundant specie with rate superior of 50%, followed by equids (about 10%) and other ungulates like roe deer, chamois, wild boar and ibex and with hare, aurochs and carnivores sporadic presence. in the lateglacial stratigraphic sequences of ortucchio cave, la punta cave, maritza cave (alhaique & recchi, 2001; alhaique, 2003; 2005), located at about 700 m a.s.l. on the hills surrounding the fucino basin, there is a large presence of small animals (especially at ortucchio, less at maritza), in particular hare, but marmot and stoat are also present; among the ungulates chamois and red deer prevail, followed by ibex, wild boar, roe deer and aurochs, with sporadic presence of equids, in particular e. hydruntinus. in the oldest sites of the area, tronci cave, maurizio shelter, ciccio felice cave (alhaique & recchi, 2003), with sequences referable in part to the last glacial maximum, the faunas are quite the same, but there is a clear prevalence of ungulates, among them equids are more abundant, marking a colder and drier climate compared to the subsequent periods. the preliminary analyses of the faunal remains from the “dig b2” and other archaeological contexts of mora cavorso cave have permit to define 15 taxa, divided into 5 orders, 10 families and 13 different genera of mammals. m. marmota and c. ibex are the most significant species both from the “sinkhole” and from the “dig b2” mammal assemblages, but is even important the c. elaphus presence, and a particular attention deserves also c. fiber, till now not signaled in lateglacial mammal assemblages of central italy, and the sure evidence of the italic hare. the “dig b2” mammal assemblage with marmot followed by red deer, ibex, chamois, wild boar and roe deer is referable to a moment less hard and humid of first data on the latest pleistocene mammals from mora cavorso cave (jenne, latium, central italy 139 the last glacial episode final phases (probably the first part of the lateglacial preceding the bølling allerød temperate oscillation), according to the cultural chronology and the radiometric dating. the “sinkhole” mammal assemblage with marmot and ibex, followed by the equids more abundant than red deer and wild boar, perhaps has to be referred to a different moment, more cold and arid. at least part of the animals from the “dig b2” has been introduced in the cave by epigravettian human groups frequenting the upper aniene river valley and the simbruini mounts during the latest pleistocene. these data on the latest pleistocene mammal faunas from mora cavorso cave, suggest some chronological, climatic and environmental indications that will be adequately investigated and better outlined during the prosecution of the archaeological and palaeontological searches. acknowledgements we are grateful to the “soprintendenza per i beni archeologici del lazio”, in particular to annalisa zarattini, which allowed the access to the fossils and to two anonymous referees for the useful suggestions that improved the quality of the manuscript. we thank also carmelo petronio, olga rickards and raffaele sardella for their support. references alessio m., alhaique f., allegri l., bietti a., branca m., d’arpino a., improta s., kuhn s., palmieri a.m. & preite martinez m. 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(2003) archeozoologia dei livelli dell’epigravettiano finale di grotta romanelli (castro, lecce). strategie di caccia ed economia di sussistenza. in: p.f. fabbri, e. ingravallo & a. mangia (eds), grotta romanelli nel centenario della sua scoperta (1900-2000), pp. 169-216, congedo, galatina (lecce). ucelli gnesutta p., boschian g., cantoro g.l., castiglioni e., dini m., maspero a., petrinelli pannocchia p. & rottoli m. (2007) i livelli epigravettiani della grotta delle settecannelle (viterbo). riv. sci. preist., 56, pp. 127-183. wilkens b. (1991) resti faunistici ed economia preistorica nel bacino del fucino. atti del convegno “il fucino e le aree limitrofe nell’antichità”, pp. 147153, archeoclub d’italia marsica, roma. ms. ricevuto il 5/05/2010 testo definitivo ricevuto il 28/8/2010 ms. received: may 5, 2010 final text received: august 28, 2010 sess 1_160211.pub il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 upper pleistocene-holocene relative sea level changes at pianosa island (tuscany archipelago): geological, geomorphological and archaeological markers 1luca maria foresi, 2fabrizio antonioli, 3maurizio d’orefice, 4silvia ducci, 5marco firmati, 3roberto graciotti, 3marco pantaloni, 4paola perazzi & 6claudia principe 1dipartimento di scienze dellaterra, università di siena, siena 2enea, casaccia, roma 3ispra – servizio geologico d’italia, roma 4soprintendenza per i beni archeologici della toscana, firenze 5museo archeologico del distretto minerario di rio nell’elba, livorno 6istituto di geoscienze e georisorse, archaeomagnetic laboratory, pisa corresponding author: l. m. foresi <foresi@unisi.it> abstract: foresi l.m. et al., upper pleistocene-holocene relative sea level changes at pianosa island (tuscany archipelago): geological, geomorphological and archaeological markers. (it issn 0394-3356, 2011). based on geological, geomorphological and archaeological markers, we provides new data and interpretations on the relative sea level change occurred at pianosa island (italy) since the last 125 ka. the mis 5.5 deposits are characterized by a 2 m thick whitish fossiliferous calcarenite, cropping out at a maximum altitude of 4 m a.s.l. containing strombus bubonius. archaeological remains provide evidence of sea level change for the last 8 ka. particularly useful are some fishtanks and a quarry cut around 2 ka bp (roman age). riassunto: foresi l.m. et al., variazioni relative del livello del mare nell’isola di pianosa (arcipelago toscano) nel pleistocene superiore-olocene: markers geologici, geomorfologici e archeologici. (it issn 0394-3356, 2011). in base a dei markers geologici, geomorfologici ed archeologici, vengono forniti nuovi dati e interpretazioni sulle variazioni relative del livello del mare avvenute nell’isola di pianosa a partire dagli ultimi 125 ka. i depositi del mis 5.5 sono caratterizzati da una calcarenite fossilifera biancastra contenente strombus bubonius, affiorante fino ad un’altezza massima di 4 m s.l.m. i resti archeologici forniscono evidenze della variazione del livello del mare per gli ultimi 8 ka. particolarmente utili a tale scopo sono alcune peschiere e una cava, entrambe realizzate intorno ai 2 ka (età romana). key words: relative sea level changes, geological, geomorphological and archaeological markers, pianosa island (tuscany archipelago). parole chiave: variazioni relative del livello del mare, markers geologici, geomorfologici e archeologici, isola di pianosa (arcipelago toscano). the bedrock of the island consists of three neogene sedimentary formations (graciotti et al., 2003). the turbiditic marly-clays facies of the marina del marchese formation are burdigalian in age (bossio et al., 2000; foresi et al., 2000) and show a maximum visible thickness of about 150 m. this unit is underlain by the golfo della botte formation, about 300 m thick, made of marly clay with arenaceous and conglomeratic intercalations. the golfo della botte formation is upper tortonian – lower messinian in age, and deposited in a lacustrine lagoonal environment. the pianosa formation dated as middle pliocene – lower pleistocene consists of very fossiliferous biocalcarenites and sands with a maximum thickness of 30 m, which unconformably overlies the miocene units. in recent studies (graciotti et al., 2003; foresi et al., 2007), the authors consider this formation composed of two different units separated by a reddish-brown layer consisting of well-lithified carbonates and iron oxides and phosphates. the deposition occurred on a submarine ridge characterized by shallow water (foresi et al., 2007). the pianosa formation is covered by whitish fossiliferous calcarenite, about 2 m thick, outcropping approximately 3÷4 m a.s.l. the typical malacofauna was described by several authors (foresi et al., 2007 and reference therein) and it consents to refer this unit to the last interglacial (125 ka). these deposits are covered by red sand with clayey matrix, locally cemented, and continental breccias with red silty-sandy matrix, this units dated as upper pleistocene. pianosa has a characteristic flat sub-triangular shape, gently tilted east, due to the geological features. evidence from geomorphological analysis suggest that landscape evolution is mainly related to coastal-marine and karst processes. coastal morphology is characterized by a series of typical landforms: cliffs, wave-cut platforms, tidal 32 34 33 notches, arches, and bays. karst processes produced typical epigean (dissolution flutes, dissolution grooves, dissolution plans) and remarkable development of hypogean features. the hypogean karst of pianosa consists in caves and conduits, with a mainly horizontal development, articulated on several levels. numerous caves have the entrances to the current sea level. these are characterized by speleothemes. in the caves lithic artifacts of the final phase of the upper palaeolithic were found (la morgia & spinelli, 1994), as well as bone breccias composed of herbivorous and carnivorous animals. a clear difference exist between the western and eastern parts of the island. the former has steep cliffs and is characterized by a deep and wide inlet (golfo della botte). the latter shows less steep coasts dipping toward the east, articulated and indented due to the presence of rocky heads, small bays, and abrasion platforms. this peculiar geomorphological context is closely related to the geological setting. along the estern coast the base of the cliff is formed by the highly erodible miocene sediments, the plio-pleistocene pianosa formation which is more resistant to wave dynamics, crops out along the eastern coast. the geomorphological evolution of the island is almost driven by eustatic and tectonic movements that affected repeatedly the northern tyrrenian sea. transgressive cycles are marked by wave-cut platforms. two main orders of marine abrasion surfaces are documented at about 2÷4 m and 22÷25 m a.s.l. the wave-cut platforms of the first order (2÷4 m) outcrops anywhere along the coast, except where outcrops marly-clayey miocene sediments which favour the formation of steep cliffs because highly erodible. the wave-cut platforms of the second order, which coincide with the summit topographic surface, are fig. 1 the marzocco fishponds (pianosa island) during low tide. the arrow on the left indicates the hole communicating with sea in the southern wall. the arrow on the right box indicates the measurement of the top of separating pools wall. la peschiera del marzocco (isola di pianosa) durante la bassa marea. la freccia sulla sinistra indica il foro nel muro meridionale comunicante con il mare. la freccia sul riquadro di destra indica la misura della parte superiore del muro di upper pleistocene-holocene relative sea level ... 34 ms. received: testo ricevuto il located along the western and southern coast characterized by active cliffs. here the erosion surfaces truncates sharply clinostratified ramps of the pianosa formation. a marine ingression occurred during the last interglacial (mis 5.5 of the isotopic curve) when the mean sea level was higher than the present. this phase is represented by the basal erosion surface at an elevation of 2÷4 m a.s.l., by lithodome holes placed at various levels, up to 7 m a.s.l., and by backward paleocliffs. during uppermost pleistocene the sea level was considerably lower than the present and induced the emersion of wide areas. this condition favoured the development of karst process, particularly during the low-stand period (about 20 ky bp), when carbonatic rocks was widely exposed, and the deposition of continental breccias. in order to detail the decimetric vertical displacements for the last 2 ka, the roman age archaeological remains were studied. they were drawn in 1989 and the altitude of archaeological markers was not corrected for tide, but they have been included in this research because are indispensable to understand the shape, the functionality and where take the scuba measurements. some architectural elements (fishtanks and cetaria), were measured during the course of scuba research operation and subsequently corrected for tide and pressure. comparing the predicted sea level curve (lambeck et al. 2011) with the collected data it is possible to observe that the values lie a few centimeters below the predicted sea level curve. this result was obtained using as markers both the holes in the radial walls of the agrippa fishponds and the altitude of the uppermost walls that separate the different pools, which indicate the same altitude (fig. 1). in conclusion, based on the data obtained from analysis of the mis 5.5 age inner margin altitude and archaeological markers relating to the various types of settlements dated between 2.1 ka and 1.5 ka bp it is possible to establish that the island of pianosa has remained tectonically stable since at least 125 ka. references bossio a., cornamusini g., ferrandini j., ferrandini m., foresi l.m., mazzanti r., mazzei r. & salvatorini g. (2000) l’evoluzione sedimentaria neogenica dell’area tirrenica settentrionale (toscana marittima, isola di pianosa, bacino di aléria). in proocedings of the environment et identité en mediterranée congress. corte, france. foresi l.m., aldinucci m., sandrelli f. & cornamusini m. (2007) guida per l’escursione geosed all’isola di pianosa. in field trip guide of geosed 2007 congress, siena, italy. foresi l.m., cornamusini a., bossio a., ferrandini m., mazzei r., salvatorini g. & argenti p. (2000) the miocene sedimentary succession of the pianosa island, northern tyrrhenian sea. in proceedings of “evoluzione geologica e geodinamica dell’appennino” in memoria del prof. g. pialli. foligno, italy, 155-157. graciotti r., foresi l.m. & pantaloni m. (2003) caratteristiche geomorfologiche dell’isola di pianosa (arcipelago toscano). atti soc. tosc. sc. nat. ser. a, 108, 95-112. lambeck k, antonioli f., anzidei m., ferranti l., leoni g., scicchitano g. & silenzi s. (2011, in print) sea level change along italian coast during holocene and a proiection for the future. journal of quaternary international. la morgia j. & spinelli g.p. (1994) localizzazione e collegamento ai documenti di archivi di caverne naturali e grotte artificiali di interesse paletnologico e geologico nell’isola di pianosa – arcipelago toscano. geoarcheologia, 2, 7-38. l.m. foresi et al. january 15, 2011 15 gennaio 2011 microsoft word 00_indice_lm04.docx il quaternario it issn 039-3356 italian journal of quaternary sciences 24 (1), 2011 103-112 stephanorhinus kirchbergensis (jäger, 1839) from the middle pleistocene deposit of riano (rome, central italy) luca pandolfi dipartimento scienze della terra, università di roma sapienza, roma correspondent author: <l.pandolfi@yahoo.it> abstract: pandolfi l., stephanorhinus kirchbergensis (jäger, 1839) from the middle pleistocene deposit of riano (rome, central italy). in this work the rhinoceros remains discovered in the site of riano are analyzed. the remains are preserved in museum of paleontology of university “sapienza” of rome and they have been recovered in a diatomaceous deposit together with remains of elephas antiquus, cervus elaphus rianensis and dama clactoniana. the faunal assemblage of riano can be correlated with torre in pietra faunal unit on the base of fossil mammal fauna and stratigraphical data. rhinoceros remains belong to only one individual and consist of various postcranial elements. morphological and morphometrical characters of the remains are comparable with eurasian rhinoceros s. kirchbergensis. this species has been rarely recorded, although the distribution range has been relatively wide. s. kirchbergensis has been discovered in a large part of europe and in the early and middle pleistocene deposits of central asia, where the species has probably origin. riano is one of the few european localities where post-cranial remains of s. kirchbergensis are reported. riassunto: pandolfi l., stephanorhinus kirchbergensis (jäger, 1839) dal deposito del pleistocene medio di riano (roma, italia centrale). in questo lavoro vengono analizzati i resti di rinoceronte rinvenuti nel bacino diatomitico di riano e conservati presso il museo di paleontologia dell’ università “sapienza” di roma. la fauna a grandi mammiferi, rinvenuta negli stessi depositi da cui proviene il rinoceronte, è composta da elephas antiquus, cervus elaphus rianensis e dama clactoniana; il sito è correlabile, per composizione faunistica e stratigrafia, con l’unità faunistica di torre in pietra. i resti di rinoceronte, composti da diverse parti dello scheletro post-craniale e appartenenti ad un unico individuo, presentano caratteristiche morfologiche e morfometriche comparabili con la specie euroasiatica s. kirchbergensis. questa specie, nonostante occupasse un vasto areale, è relativamente rara e probabilmente ha origine in asia centrale, da dove provengono le segnalazioni più antiche riferite al pleistocene inferiore. la presenza di s. kirchbergensis nel sito di riano rappresenta una delle poche in europa in cui vengono descritti resti dello scheletro post-craniale di questa specie, prevalentemente conosciuta sulla base di denti isolati. key words: stephanorhinus kirchbergensis, middle pleistocene, riano. parole-chiave: stephanorhinus kirchbergensis, pleistocene medio, riano. 1. introduction the site of riano is situated 20 km north of rome and is characterized by tufaceous-diatomitic formation. this last is lying on the “yellow vacuolized tuff” of the pleistocene tufaceous series of “vulcano sabatino” (ambrosetti et al., 1969, 1972; accordi & maccagno, 1962; bonadonna & bigazzi, 1969). in the past century, from the diatomaceous levels, well-preserved and almost complete vertebrate skeletons have been discovered. among the others, the fossil fauna is represented by elephas antiquus falconer & cautley, cervus elaphus rianensis leonardi & petronio, dama clactoniana (falconer), several fishes, amphibians and reptiles (maccagno, 1962; accordi & maccagno, 1962; mastrorilli, 1965; leonardi & petronio, 1974; caloi et al., 1980). the fossil flora is well represented by several forest assemblages (follieri, 1958a; 1958b; 1962) that allow to well-reconstruct the climatic conditions near riano during the middle pleistocene. the landscape around the site was characterized by a dense forest, with a remarkable biodiversity compared to coeval records of vegetation in central and northern europe. the modern analog of this landscape may be found in areas with over 2000 mm mean annual precipitation, favouring the development of such a dense forest. in particular, three forest phases are recognised: a mixed oak forest at the basis, followed by a period with dominant pterocarya kunth, and by a final phase with a progressive increase of abies miller and fagus linnaeus pollen and the decrease of that of pterocarya (ambrosetti & bonadonna, 1967; follieri, 1962; follieri & magri, 2001). ambrosetti et al. (1972) and bonadonna & bigazzi (1969) proposed, for the diatomaceous deposit of riano, the formation name ‘rianian’ to cover the late middle pleistocene in the stratigraphical scheme for the tyrrhenian margin in central italy. on the basis of stratigraphical relationships and faunal characteristics, malatesta (1978) regarded these deposits as strictly representing the continental facies equivalent to the fluvio-lacustrine-brackish-marine sediments that form the aurelia formation and, according to caloi et al. (1998), this deposit can be correlated with torre in pietra faunal unit (sensu gliozzi et al., 1997). l. pandolfi 104 2. materials and methods the nomenclature used in this work was set by fortelius et al., (1993). also, according to groves (1983) the pleistocene european rhinoceroses show little similarity with the genus dicerorhinus gloger and they are ascribed to genus stephanorhinus kretzoi, as previously used by several authors (heissing, 1973, 1981, 1989; cerdeño, 1993, 1995, 1998; prothero et al., 1986; inter alios). rhinoceros remains found in the site of riano are preserved in the museum of paleontology of “sapienza” university of roma (mpur). some of the remains are unpublished while some of them are previously ascribed to dicerorhinus cf. mercki kaup (leonardi & petronio, 1974; guérin, 1980). later, the rhinoceros of riano has been reported in literature as dicerorhinus cf. hemitoechus falconer, stephanorhinus sp., stephanorhinus cf. hemitoechus (caloi et al., 1980, caloi & palombo, 1994; palombo et al., 2002). ). the remains analyzed have been found in the ’70ties of the past century in the cave of diatomaceous earth of valle dell’inferno (riano) (petronio, pers. com.). in the same cave, in the ’60ties of the past century, the skeletons of cervus elaphus rianensis have been discovered. the rhinoceros remains belong to the same individual and some of them have been found articulated. also, the rhinoceros lacks of the cranial portion and preserves several post-cranial elements among the os coxae, femurs, calcaneum, talus. the most of post-cranial elements are damaged or deformed by characteristics of the fossiliferous site, therefore some morphometrical characters can not be taken into account. morphological characters considered are those listed as diagnostics by several authors, including guérin (1980), fortelius et al. (1993), lacombat (2005). when possible, the morphometric methods are based on the works of guérin (1980), mazza (1988), fortelius et al. (1993), lacombat (2005). 3. specimens studied and comparations the rhinoceros remains from riano are represented by several elements of post-cranial skeleton and fragments of bones. the principal elements of the skeleton are reported and described below. 3.1 vertebrae the vertebral column is represented by several thoracic and lumbar vertebrae (mpur 7/1-7/16) in a different state of preservation (fig. 1). some of them are articulated with other vertebrae and ribs (mpur 7/217/25). also, among the vertebrae is present the proximal portion of an atlas, very damaged. due to the deformation and damage of the remains, no morphological characters or morphometric values can be taken into account. 3.2 scapulae (mpur 7/54) two scapulae are present, one right and one left, articulated with the ribs. the scapulae are compressed latero-medially and are very damaged (fig. 1). the left scapula preserved only the proximal portion, while, the right one preserved the proximal portion (depth of the proximal portion > 212 mm) and the spine. no diagnostic character is present in the preserved portions. 3.3 humeri two humeri are present; one of them preserved only the diaphysis (mpur 7/69) and a portion of the proximal articular surface (mpur s.n.). the other one preserved the diaphysis and a very damaged proximal epiphysis (mpur 7/56) (fig. 1). the dimensions of the diaphysis (breadth = about 65 mm; depth = > 65 mm) seem not to be helpful to distinguish between the different rhinoceros species. in fact, the dimensional ranges of the diaphysis of the european pleistocene rhinoceroses are quite similar (cfr. guérin, 1980). the proximal articular surface is almost intact and have a circular outline. the approximate dimensions (breadth = > 80 mm; depth = > 90 mm) allow to exclude that it can be ascribed to s. etruscus falconer (cfr. fortelius et al., 1993). 3.4 sacrum (mpur 7/20) the sacrum (maximal breadth = about 167 mm; maximal length = > 165 mm) is articulated with some lumbar vertebrae (mpur 7/17-7/19) (fig. 1). no morphological or morphometrical study has been done on the sacrum of european pleistocene rhinoceroses. considering that, the comparison with other specimens is very difficult. 3.5 os coxae several fragmentary portions of the os coxae are present (mpur 7/59-7/65). also, the left os coxae is almost intact (mpur 7/57) and the articular surface of the right os coxae is present (mpur 7/58). the acetabulum is relatively broad, deep and sub-elliptical, compressed dorsally (fig. 1). this shape seems not to be present in s. etruscus, s. hundsheimensis toula and s. hemitoechus (cfr. lacombat, 2005); it is more similar to s. kirchbergensis jäger from taubach (cfr. portis, 1878). also, posteriorly, the acetabulum is separated into two articular lips; a dorsal and a ventral one. the dorsal lip is inclined posterior-ventrally and is much wider and longer that the ventral one (fig. 1). these characters allow to distinguish this bone from those of s. etruscus, s. hundsheimensis and s. hemitoechus (cfr. lacombat, 2005), and seem to be present in s. kirchbergensis from taubach (cfr. portis, 1878). also, unlike s. hemitoechus, in the os coxae from riano the pit of acetabulum is well-evident (cfr. lacombat, 2005). the dimensions of the acetabulum are much larger than s. etruscus from upper valdarno. the value of the maximal length of the acetabulum is much greater than s. hemitoechus and it is more similar to the maximal values of s. hundsheimensis (tab. 1). also, the values of the diaphysis of the ilium and the height of the acetabulum appear relatively large in the specimens of riano (tab. 1). 3.6 femurs the two distal epiphysis of the femurs (mpur 7/66; mpur 7/68) and a damaged portion of the right proximal epiphysis are preserved (mpur 7/70) (fig. 2). the proximal articular surface is partially damaged in the medial portion and seems to be slightly compressed dorso-ventrally (fig. 2). in proximal view, it seems to be much developed and much compressed latero-medially compared with s. hundsheimensis from mauer (from fortelius et al., 1993) and ponte molle. the articular surfaces of the distal epiphysis of the femurs, in anterior stephanorhinus kirchbergensis (jäger, 1839) from the middle pleistocene deposit of riano … 105 fig. 1 rhinoceros remains from riano: 1) scapula, lateral view; 2) humerus, posterior view; 3) os coxae, a-dorsal view, b-lateral view of articular surface; 4) sacrum, ventral view; 5) thoracic vertebrae, right lateral view. the bar is of about 2 cm. resti di rinoceronte di riano: 1) scapola, visione laterale; 2) omero, visione posteriore; 3) bacino, a-visione dorsale, b-visione laterale della superficie articolare; 4) sacro, visione ventrale; 5) vertebre toraciche, visione laterale destra. la barra è di circa 2 cm. fig. 2 rhinoceros remains from riano: 1) femur, proximal epiphysis, proximal view; 2) femur, distal epiphysis, a-anterior-distal view, b-posterior view; 3) patella, lateral view; 4) tibia, proximal view; 5) talus, anterior view; 6) calcaneum, a-medial view, b-distal view; 7) metapodial bone articulated with first phalanx, lateral view. the bar is of about 2 cm. resti di rinoceronte di riano: 1) femore, epifisi prossimale, visione prossimale; 2) femore, epifisi distale, a-visione anteriore, b-visione posteriore; 3) rotula, visione laterale; 4) tibia, visione prossimale; 5) astragalo, visione anteriore; 6) calcagno, a-visione mediale, bvisione distale; 7) metapodiale in connessione anatomica con la prima falange, visione laterale. la barra è di circa 2 cm. l. pandolfi 106 tab. 1 comparative dimensions of os coxae from riano and of s. etruscus (s. etru.) (data from mazza, 1988), s. hemitoechus (s. hem.) and s. hundsheimensis (s. hund.) from isernia (data from lacombat, 2005). la = outer length of the acetabulum; lar = inner length of the acetabulum; lar = inner width of the acetabulum; lo = length of the foramen obturatum; bsi = breadth of the shaft of the ilium; his = height of the shaft of the ilium; ha = height of the acetabulum; ll = lateral length; ca = about. dimensioni comparative del bacino di riano e di s. etruscus (s. etru.) (dati da mazza, 1988), s. hemitoechus (s. hem.) e s. hundsheimensis (s. hund.) di isernia (dati da lacombat, 2005). la = lunghezza esterna dell’acetabolo; lar = lunghezza interna dell’acetabolo; lar = larghezza interna dell’acetabolo; lo = lunghezza del foramen obturatum; bsi = ampiezza della diafisi dell’ilium; his = altezza della diafisi dell’ilium; ha = altezza dell’acetabolo; ll = lunghezza laterale; ca = circa. tab. 2 comparative dimensions of femurs from riano and of s. etruscus (s. etru.), s. hemitoechus (s .hem.), s. hundsheimensis (s. hund.) and s. kirchbergensis (s. kirch.) (1 = data from fortelius et al., 1993; 2 = data from lacombat, 2005; 3 = data from kahlke, 1977). dtap = breadth of the proximal epiphysis; dapap = depth of the proximal epiphysis; dtd = breadth of the distal epiphysis; dapdm = medial depth of the distal epiphysis; dapdl = lateral depth of the distal epiphysis; dttr = breadth of the distal trochlea; dtcon = breadth of the posterior condyles; dtfc = breadth of the intercondyloid fossa. dimensioni comparative dei femori di riano e di s. etruscus (s. etru.), s. hemitoechus (s. hem.), s. hundsheimensis (s. hund.) e s. kirchbergensis (s. kirch.) (1 = dati da fortelius et al., 1993; 2 = dati da lacombat, 2005; 3 = dati da kahlke, 1977). dtap = diametro trasversale dell’epifisi prossimale; dapap = spessore dell’epifisi prossimale; dtd = diametro trasversale dell’epifisi distale; dapdm = spessore mediale dell’epifisi distale; dapdl = spessore laterale dell’epifisi distale; dttr = diametro trasversale della troclea distale; dtcon = diametro trasversale dei condili posteriori; dtfc = diametro trasversale della fossa intercondilea. stephanorhinus kirchbergensis (jäger, 1839) from the middle pleistocene deposit of riano … 107 distal view, are undamaged and welldeveloped (fig. 2). the trochlea is clearly asymmetric and the medial lip is much larger and developed than the lateral one. the trochlear trough is broad and deep. in medial view, the surface of the bone is broad and the tuberosity is well-evident and massive. it is situated slightly higher than the lateral one. in lateral view, the surface of the bone is less broad than the medial one and the tuberosity is much rounded (fig. 2). this morphology can be observable in the distal epiphysis of s. kirchbergensis from taubach (cfr. kahlke, 1977) and mosbach (cfr. fortelius et al., 1993) and it is different from those of the other species of the stephanorhinus genre. these last have a different development and shape of the medial and lateral tuberosities and of the articular surfaces (guérin, 1980; fortelius et al., 1993; lacombat, 2005). in posterior view, the condyles are well-developed and rounded; the intercondyloid fossa is strong, broad and deep (fig. 2). the medial condyle is much broader than the lateral one; this last is postero-laterally inclined. even these characters seem to be distinctive of s. kirchbergensis and allow to distinguish it from the other species of the stephanorhinus genre (guérin, 1980; fortelius et al., 1993; lacombat, 2005). at last, the dimensions of the femurs of riano are relatively large. they are comparable with the maximal values of s. hemitoechus and the values of s. kirchbergensis (tab. 2; tab. 7). 3.7 patellae (mpur 7/72; mpur 7/71) two patellae are preserved, one right and one left, differently damaged (fig. 2). in posterior view, two articular surfaces are present, a medial one, broad and concave, and a lateral one, less broad and concave than the former. the two articular surfaces are well-separated by a saddle. the dimensions of the bones are relatively large if compared with those of s. etruscus, s. hundsheimensis and s. hemitoechus reported by fortelius et al. (1993) and lacombat (2003) (tab. 3); in particular, the dtmax is much greater. this last character is peculiar of s. kirchbergensis (guérin, 1980) (tab. 7). 3.8 tibia (mpur 7/73) only one tibia is present. this last is very damaged and preserved the proximal epiphysis and a portion of the diaphysis. the tibia is massive, the anterior tuberosity is damaged and deformed, the tibial spine is quite salient and the interspine fossa is relatively broad (fig. 2). the lateral rim of the tibial spine is higher than the medial tab. 3 comparative dimensions of patellae from riano and of s. etruscus (s. etru.), s. hemitoechus (s. hem) s. hundsheimensis (s. hund.) and s. kirchbergensis (s. kirch.) (1 = data from fortelius et al., 1993; 2 = data from lacombat, 2005; 3 = data from kahlke, 1977). lmax = maximal lenght; la = articular lenght; dt max = maximal breadth; dta = articular breadth; dapmax = maximal depth. dimensioni comparative delle rotule di riano e of s. etruscus (s. etru.), s. hemitoechus (s. hem) s. hundsheimensis (s. hund.) e s. kirchbergensis (s. kirch.) (1 = dati da fortelius et al., 1993; 2 = dati da lacombat, 2005; 3 = dati da kahlke, 1977). lmax = lunghezza massima; la = lunghezza articolare; dt max = diametro trasversale massimo; dta = diametro trasversale articolare; dapmax = diametro anteroposteriore massimo. tab. 4 comparative dimensions of talus from riano and of s. etruscus (s. etru.), s. hemitoechus (s .hem.) s. hundsheimensis (s. hund.) and s. kirchbergensis (s. kirch.) (1 = data from fortelius et al., 1993; 2 = data from lacombat, 2005; 3 = data from kahlke, 1977). dtmax = maximal breadth; dapl = lateral depth; htrl = height of the lateral trochlea; hl = lateral height. dimensioni comparative dell’astragalo di riano e di s. etruscus (s. etru.), s. hemitoechus (s. hem.), s. hundsheimensis (s. hund.) e s. kirchbergensis (s. kirch.) (1 = dati da fortelius et al., 1993; 2 = dati da lacombat, 2005; 3 = dati da kahlke, 1977). dtmax = diametro trasversale massimo; dapl = diametro antero-posteriore laterale; htrl = altezza della troclea laterale; hl = altezza laterale. l. pandolfi 108 one. the tibial fossa, in dorsal view, seems to be relatively wide; however, this last character may have been accentuated by the deformation. the medial articular surface of the proximal epiphysis is more anteroposteriorly elongated than the lateral one. the state of preservation of the tibia does not allow to carry out an exhaustive morphometrical work. the relative dimension of the transversal diameter of the proximal epiphysis (dtp = > 129 mm) seems to be larger than s. etruscus and s. hundsheimensis (respectively dtp = 87÷110 mm and dtp = 111,5÷119 mm in fortelius et al., 1993; respectively dtp = 102÷115 mm and dtp = 103÷123,5 mm in guérin, 1980) and is closer to maximal values of s. hemitoechus (dtp = 101÷137,5 mm in guérin, 1980) and to the values of s. kirchbergensis reported by guérin (1980) (dtp = 136 mm) and kahlke (1977) (dtp = 122,5). 3.9 talus (mpur 7/76) the talus (fig. 2) is relatively damaged; in anterior view, the trochlea lacks of the medial portion; in lateral view, the articular surface is relatively wide and is posteriorly limited by a slight depression. in medial view, the distal tuberosity is well-developed and is situated in the anterior-distal margin of the medial face, unlike s. hemitoechus (guérin, 1980; lacombat, 2005). in posterior view, the proximo-lateral articular surface is welldeveloped, concave and sub-quadrangular in shape; it is elongated in the latero-distal side with a smaller articular facet. the mesio-distal articular surface have subtrapezoidal shape; it is well-separated from the proximolateral one and is relatively damaged. the maximal transverse diameter is greater than s. etruscus and s. hundsheimensis. the dimensions of the bone are comparable with the maximal values of s. hemitoechus and fall in the variation range of s. kirchbergensis (tab. 4; tab. 7). 3.10 calcaneum (mpur 7/75) in lateral view, the calcaneum (fig. 2) is slightly antero-posteriorly compressed; on the whole, the bone is massive and dimensionally large. the tuber calcanei is relatively large and high; it has an anteroposterior development similar to the beak. this last character allow to distinguish this bone from those of s. etruscus and s. hundsheimensis (guérin, 1973; 1980; lacombat, 2005). the sustentaculum talii is about perpendicular to the axis of the bone and it is slightly damaged in the medial portion. in antero-distal view, the articular surfaces are well-evident. the upper lateral articular surface has rounded shape; the articular surface on the sustentaculum talii has a clear outline and has sub-circular shape. these last articular surfaces are clearly wellseparated between them. the lower articular surface is slightly damaged and more higher than long. the articular surface with the cuboid is flat and antero-posteriorly elon gated. all these morphological characters are comparable with s. kirchbergensis and allow to distinguish from s. hemitoechus. in this last species the articular surfaces with the talus are not well-separated between them and the lower articular surface is more longer than high (cfr. guérin, 1973; 1980; kahlke, 1977). also, the dimensions of the calcaneum are relatively great and are comparable with the values of s. kirchbergensis (tab. 5; tab. 7). 3.11 cuboids (mpur s.n.) the cuboids, one right and one left, are incomplete and differently damaged. the anterior face of the bone is sub-trapezoidal in shape and the lateral side is more higher than the medial one. the lower margin of the anterior face is about straight, while the upper margin is clearly oblique. in proximal view, the articular surface seems to be flat in the anterior-lateral side and oblique in the medial side. no other morphological character is observable and the few characters present do not allow to distinguish among the species (cfr. fortelius et al., 1993; lacombat, 2005). the dimensions of the cuboids from riano are comparable with the values of s. kirchbergensis and the maximal values of s. hemitoechus (tab. 6). 3.12 great cuneiform (mpur s.n.) only one cuneiform is preserved. it is very damaged and deformed. in lateral view, two articular surfaces are visible. the proximo-medial articular surface has subtriangular shape, while the distal one is elongated. due to the deformation of the bone, no other morphological or morphometrical character is recognizable. tab. 5 comparative dimensions of calcaneum from riano and of s. etruscus (s. etru.), s. hemitoechus (s .hem.), s. hundsheimensis (s. hund.) and s. kirchbergensis (s. kirch.) (1 = data from fortelius et al., 1993; 2 = data from lacombat, 2005; 3 = data from kahlke, 1975; 1977). hmax = maximal height; dts = breadth of the tuber calcanei; daps = depth of the tuber calcanei; dtmp = minimum posterior breadth; dtst = breadth of the sustentaculum talii; dapb = depth of the beak. dimensioni comparative del calcagno di riano e di s. etruscus (s. etru.), s. hemitoechus (s. hem.), s. hundsheimensis (s. hund.) e s. kirchbergensis (s. kirch.) (1 = dati da fortelius et al., 1993; 2 = dati da lacombat, 2005; 3 = dati da kahlke, 1975; 1977). hmax = altezza massima; dts = diametro trasversale del tuber calcanei; daps = diametro antero-posteriore del tuber calcanei; dtmp = diametro trasversale minimo posteriore; dtst = diametro trasversale del sustentaculum talii; dapb = diametro antero posteriore del becco. stephanorhinus kirchbergensis (jäger, 1839) from the middle pleistocene deposit of riano … 109 tab. 6 comparative dimensions of cuboids from riano and of s. etruscus (s. etru.), s. hemitoechus (s .hem.), s. hundsheimensis (s. hund.) and s. kirchbergensis (s. kirch.) (0 = data from guérin, 1980; 1 = data from fortelius et al., 1993; 2 = data from lacombat, 2005). h ant. = anterior height; l = breadth. dimensioni comparative dei cuboidi di riano e di s. etruscus (s. etru.), s. hemitoechus (s. hem.), s. hundsheimensis (s. hund.) e s. kirchbergensis (s. kirch.) (0 = dati da guérin, 1980; 1 = dati da fortelius et al., 1993; 2 = dati da lacombat, 2005). h ant. = altezza anteriore; l = larghezza. 3.13 metapodial bone (mpur s.n.) very fragmentary metapodial bone is preserved. it consists of a distal epiphysis articulated with the first and second phalanges (fig. 2). no morphological or morphometrical character are recognizable. 4. discussion and conclusions even if partially damaged, the rhinoceros remains from riano preserve some characters, such as the articular surfaces, which allow an accurate analysis. in particular, the shape and size of the articular surfaces and tuberosities of the femurs, the characters of the os coxae and the morphology of the calcaneum of the rhinoceros from riano are comparable with s. kirchbergensis (cfr. guérin, 1973; 1980; fortelius et al., 1993). moreover, the size of the remains fall into the variation range know for s. kirchbergensis (cfr. kahlke, 1977; guérin, 1980; fortelius et al., 1993). s. kirchbergensis seems to be a relatively rare species, although it is reported in most of europe and asia (guérin, 1980; tong, 2001; lacombat, 2005; billia, 2008; billia & petronio, 2009). this rarity could be related with the ethology of the species; probably, it was present in the area with groups of few individuals. however, it can be assumed that the species living in ecological niche unfavourable for its fossilization (loose, 1975). in this regards, the species seems to be typical of forest environments; this hypothesis is supported by the brachydont teeth of the species and by the remains of flora and fauna that have been discovered with this species (guérin, 1980). recently, s. kirchbergensis has been found in sites of southern china, 2000 m above sea level, that correspond to temperate deciduous and coniferous forest (tong & wu, 2009). the fossil flora of riano, discovered with the rhinoceros remains, bear out the hypothesis that species could be typical of forest environments. this fact could be explain the relatively absence or rarity of the species in southern italy, in the iberian peninsula and in north africa, unlike to the coeval european species s. hemitoechus (guérin, 1980; cerdeño, 1990; billia & petronio, 2009). the phylogenetics of s. kirchbergensis is still unresolved. this species is directly connected to larterotherium megarhinus (de christol) by würst (1922), staesche (1941) and guérin (1980), even if the evolutionary connections between the two species are not clear much. however, s. kirchbergensis seems to has origin in central asia. in fact, it is reported in early pleistocene sites of china and kazakhstan (khisarova, 1963; dong et al. 2000; tong & moigne, 2000; tong, 2001; billia & petronio, 2009; tong & wu, 2009). later s. kirchbergensis is present in the middle pleistocene deposits of russia and eastern europe (czyżewska, 1962; borsuk-bialyńicka & jakubowski, 1972; billia & shpansky, 2005; billia, 2008). the species may be evolved in central asia from a common ancestor of the evolutionary lineage that led to s. hemitoechus in europe. later, it would spread westward during the middle pleistocene. in this regards, an exhaustive analysis of mio-pliocene asian rhinoceros remains would confirm this hypothesis. in italy, the oldest remains ascribed to s. kirchbergensis are those discovered in the middle pleistocene sites of valdemino (nocchi & sala, 1997) and ponte molle (capasso barbato et al., 1998; billia & petronio, 2009), both correlable with isernia fu (sensu gliozzi et al., 1997). also, the species is reported in few sites of late middle pleistocene of northern and central italy and it seems to be absent in the second part of late pleistocene (petronio et al., 2007). however, the most part of the remains ascribed to this species consist of isolated teeth. the remains of riano are, instead, one of the rare record in europe of s. kirchbergensis based on post-cranial elements belonging to a single individual. l. pandolfi 110 tab. 7 comparative dimensions of femurs, patellae, talus and calcaneum from riano and of s. hemitoechus (s .hem.), s. hundsheimensis (s. hund.) and s. kirchbergensis (s. kirch.) reported by guérin (1980). dimensioni comparative dei femori, delle rotule, dell’astragalo e del calcagno di riano e di s. hemitoechus (s .hem.), s. hundsheimensis (s. hund.) e s. kirchbergensis (s. kirch.) dati da guérin (1980). acknowledgements thanks to prof. c. petronio for critical review and support. also thanks to two anonymous reviewers, prof. h.w. tong, prof. m. follieri, prof. d. magri, dr. r. manni and sig. l. riti. references accordi b. & maccagno a. m. 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(2009) stephanorhinus kirchbergensis (rhinocerotidae, mammalia) from the rhino cave in shennongjia, hubei chinese science bulletin, 55 (12), pp. 1157-1168. wüst e. (1922) beiträge zur kenntnis der diluvialen nashörner europas centralbl. f. min. geol. u pal., 20, pp. 641-656; 21, pp. 680-688. ms. ricevuto il 13/05/2010 testo definitivo ricevuto il 4/08/2010 ms. received: may 13, 2010 final text received: august 4, 2010 available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 43 48 palaeoecology and taphonomy of the straight-tusked elephant late middle pleistocene site of poggetti vecchi (southern tuscany, italy) chiara capalbo 1,2 , paul p.a. mazza 1 , federico masini 2 , andrea savorelli 1 1 dipartimento di scienze della terra, università di firenze, firenze, italy 2 dipartimento di scienze della terra e del mare (distem), università di palermo, palermo, italy corresponding author: c. capalbo <chiaracapalbo@gmail.com> abstract: works for the construction of thermal pools at poggetti vecchi, near grosseto (tuscany, italy) exposed an accumulation of fossil bones, largely belonging to the straight-tusked elephant palaeoloxodon antiquus, mixed up with stone and wooden tools. the site is radiometrically dated to the late middle pleistocene, and the artefacts were thus created by early neanderthals. palaeobiological and taphonomic analyses of the fauna remains are part of a more general, multiproxy study of the site that provides new information on mis 7-6 transition, as well as on human-animal interactions. keywords: palaeoclimate, palaeoenvironment reconstruction, palaeobiology, taphonomy, elephants 1. introduction poggetti vecchi is an open-air archaeopalaeontological site confined within a narrow valley and located in southern tuscany (central italy), some 5,5 km wnw of roselle and 7 km nw of grosseto (42° 49'8.92" n, 11° 4'19.41" e, fig. 1). the fig. 2 shows the aerial view of the site, from bing map (https:// www.bing.com/maps/?cc=it) with details and annotation concerning the location of the cores s1 and s2 and log a and b. the excavation exposed an about 3 m thick sedimentary succession, deposited in a very narrow bay through alternating phases of accumulation and erosion. all in all, seven lithostratigraphical units, of either terrigenous or carbonate nature, have been recognized (u1u7, fig. 3). vertebrate bones, mixed up with stone tools and wooden multipurpose digging sticks, were discovered mainly in the lower portion of the succession (unit 2). the remains are overlain by thermal carbonates, radiometrically dated to 171 ±3 ka (benvenuti et al., 2017). based on this dating the human artifacts can be assigned to early neanderthals; this sparks interest in the site, especially from a geoarchaeological perspective. the utilization of this multidisciplinary approach at poggetti vecchi provided valuable new insights into the human and animal life in this period of time and in this part of italy where palaeontological and prehistoric discoveries had never been reported before. 2. materials and methods the vertebrate assemblage includes straight-tusked elephant palaeoloxodon antiquus, aurochs, red deer, roe deer, fallow deer, a very advanced transitional speleoid bear ursus deningeri-spelaeus, emys orbicularis, hierophis viridiflavus, and undetermined birds. there are also many small mammals, including watervole arvicola amphibius and several other voles [microtus cf. arvalis, microtus (terricola) ex gr. savii and microtus sp]. most of the bones (a total of 747) were found in unit 2. palaeobiological and taphonomic analyses here presented have been integrated into a geoarchaeological multiproxy study of the site. the relative abundances of the taxa from the different layers were expressed in number of identified specimens (nisp) and minimum number of individual (mni) counts. specimens have been attributed to individuals by side matching, taking into account several characteristics, such as size, relative proportions, the degree of fig. 1 geographical map of southern tuscany showing the https://doi.org/10.26382/aiqua.2018.aiquaconference https://www.bing.com/maps/?cc=it https://www.bing.com/maps/?cc=it ossification, age and state of preservation. to avoid biases induced by different fragmentation potential, the nisp was calculated separately for each of three distinct size classes (<10-100 kg; 100-300 kg; >300 kg). the poggetti vecchi fauna comes from a lacustrine marginal deposit; the susceptibility of the specimens to hydraulic transport and fluvial scattering had to be estimated by adopting vorrhies’ approach (behrensmeyer, 1975; villa & mahieu 1991; voorhies, 1969). bone surface modifications (preand post-depositional) were sought for using conventional analytical approach. the degree of weathering was evaluated following behrensmeyer’s (1978) weathering stages (from stage 0 – non altered to stage 5 – heavily altered). the palaeobiology of the poggetti vecchi mammals (age and sex) have been assessed based on different proxies. ontogenetic ages were calculated from the degree of ossification and epiphyseal fusions (roth, 1984; kangwana, 1996; lister, 1999; reitz & wing 2010; speth, 2000; herridge, 2010), as well as from tooth eruption and wear (laws, 1966; krumrey & buss 1968; brown & chapman 1991; haynes, 1991; hillson, 2005; rasmussen et al., 2005). some of poggetti vecchi’s mammal remains have been tentatively sexed, aiming at assessing the relative frequencies of males and females. palombo & villa (2003) was followed to sex the remains of palaeoloxodon antiquus. 3. results the macromammal assemblage from unit 2 is dominated by very large herbivores: the straight-tusked elephant palaeoloxodon antiquus and the aurochs bos primigenius (39.9% and 19.4% of the largest species, respectively). based on the developmental stages of different skeletal remains (skull, mandible, molar, and tusk) from unit 2, palaeoloxodon antiquus is represented by a total of 7 individuals: three juveniles of 1-8 years, one 14-15-year-old sub-adult, two 20-30-year-old adults, and one individual older than 40 years. the skulls are crushed into splinters; a fairly complete, but poorly preserved, tusk (n.162) belongs to one of the prime adult individuals. based on the criteria proposed by palombo & villa (2003) and lister (1996), the assem 44 fig. 2 aerial view of the site with the location of cores s1 and s2 and logs a and b as reported in fig. 3. (the figure was drawn from benvenuti et al., 2017). capalbo c. et al. 45 blage from poggetti vecchi’s unit 2 includes elements of both males (i.e., the right pyramidal 987 has the articular surface for the unciform largely overlapping the hooked process; the right uncinate 295 bears an elongated and straight joint surface for metacarpal v) and females (i.e., the right coxal bone 5245 with the wing of the ileum shaped like that of female individuals of mammuthus). the bones retrieved from the dark clay sediments of unit 2 had subhorizontal orientation, and were concentrated in a ne-sw-trending strip. they were found juxtaposed with little or no sediment in between. the general state of preservation of the bones is good; almost all, however, are broken and have severely scratched surfaces (37,2%). the relative skeletal frequencies of the site’s best-represented species, i.e., palaeoloxodon antiquus and bos primigenius, gave revealing results. the vertebrae, ribs, basipodial bones, and phalanges of p. antiquus are unexpectedly underrepresented whereas the opposite occurs for b. primigenius (fig. 3). due to their high fragmentation, ribs are generally overestimated in the nisp counts. the analysis of the collection of remains of palaeoloxodon antiquus reveals that easily winnowed bones of the voorhies groups i (i.e., ribs and vertebrae) and i & ii (i.e., phalanges) are under-represented; in contrast, the modestly transportable ones, belonging to voorhies group ii (i.e., humerus, radius, pelvis, femur, tibia, metapodial) and the lag elements of voorhies group iii (i.e., skull, mandible), are quite more numerous. moreover, the elephant bones show relatively low incidence of abrasion/polishing (18.63%). conversely, bos primigenius, cervus elaphus and capreolus capreolus are largely represented by bones that are susceptible to hydraulic transport and most of them are polished and show evidence of abrasion. based on nisp counts, virtually all the hardparts are broken (95%). most (23%) were fractured in dry state and only 6% in fresh state; spiral fractures are rare (3,7%). very few bones (2.5%) have undergone modest weathering (1.7% are in weathering stage 1, and 0.7% in weathering stage 1/2-2: behrensmeyer 1978). root etching (1.9%) was observed on the bone surfaces and, sometimes, also on the fractures. humic corrosion evifig. 3 correlation of stratigraphical data along the cross section showed in fig. 2. (the figure was drawn from benvenuti et al., 2017). men and elephants in prehistoric maremma dence is very low (1.1%). a few bones (5%) show evidence of scavenging. the size of the scoring marks, pits and bites are suggestive of a predator or scavenger with blunt pointed teeth. the occurrence of rare hyena coprolites and of an erratic left second lower premolar of the spotted hyena crocuta crocuta attest to the presence of these carnivores at the site. finally, only three specimens show evidence of human-derived modification: the lateral portion of the diaphysis of a left humerus of bos primigenius, the basal portion of a shed right antler and a fragmental diaphysis of a tibia of cervus elaphus. both humerus and tibia are very polished. 4. discussion and conclusion the radiometric datings from unit 4 locates the whole section at a time period between late mis 7 and late mis 6. the geological and palaeobiological reconstructions of the site are detailed in benvenuti et al. (2017). the evidence accumulated by this multiand interdisciplinary teamwork unraveled the succession of events that occurred during the deposition of the poggetti vecchi sedimentary succession (units 1-6). four different flooding events were detected, separated by regressions. during the flooding episodes, homogeneous organic muds deposited in this shallow, protected lacustrine setting; in contrast, vertebrate remains and human artifacts accumulated on the erosive surfaces that formed during the regressions. the fossil records tell us that at the time when the fossiliferous site was formed, the area was dominated by extensive open grassland inhabited by large herbivores, among which palaeoloxodon antiquus and bos primigenius, whereas the red and roe deer probably browsed in sparse groves. this outline is confirmed by the abundant herbaceous plant pollen, especially of poaceae, which dominates the spectra along all the stratigraphy. the abundant frequency of freshwater fens, together with the high variety of wetland plants and rich mollusk and ostracod assemblages recorded along the whole sedimentary succession, confirm periodic fluctuations of groundwater seeps and freshwater bodies. in particular, palaeooecological insights indicate that the unit 2 fauna was well-tuned with the climatic and environmental fluctuations that occurred within the short time period between the onset of mis 6 (lake lowstand and subaerial erosion at the transition from unit 1 to unit 2) and the next interstadial (lake highstand phase and deposition of sedimentary units 3-4). the palaeobiological inferences from the small and large mammal assemblages are coherent with the succession of palaeoenvironmental signals and sedimentary events and their tuning with the main climatic fluctuations. poggetti vecchi differs from other similar sites in many respects (e.g. stratigraphical age, number of elephants involved, kind of artifacts). the lack of palaeobiological and taphonomic evidence for active hunting suggests that the elephants probably died from some natural, catastrophic event. the presence of females and males of a wide age spectrum and the bone-to-bone contact (with virtually no sediment in between) of their remains suggest that the elephants were components of a family group, which likely died altogether at the same time. a plausible scenario to account for these simultaneous deaths could be a very intense cold snap, beyond the elephants’ thermal tolerance limits and too sudden to flee from. based on these insights, it can be speculated that the narrow valley of poggetti vecchi, with its geothermal hot springs, offered a shelter to the elephant clan during a particularly cold season during the transitional mis 7-6 time span. it can be speculated that by being forced to stay near the only heat source, they consumed all the vegetation in the surrounding area and finally died of starvation. the accumulated evidence indicates that the carcasses lied largely unexposed and inaccessible to predators, presumably at least partially immersed in water. decomposition then progressed in the conservative environment until complete skeletonization. after this, the skeletons were disarticulated, and the bones scattered nearby, presumably by occasional (seasonal) streams of water. palaeobiological and taphonomical data suggest the death of elephants cannot be associated with active hunting, although elephants were butchered soon after their death. the high amount of stone and wooden implements that were found closely interspersed among the bones, all over the area, is an indisputable sign of animal human interaction. hence it likely suggests that 46 fig. 4 frequencies of skeletal parts (observed versus mni-based expected amounts of bones). a) palaeoloxodon antiquus; b) bos primigenius. in a) we notice a marked under-representation of axial bones, basipodial bones and phalanges. a b capalbo c. et al. humans managed to access the great amount of flesh that the lucky circumstances made available. the wear patterns on the edges of stone tools indicate butchering actions on soft animal tissues, but also the scraping or shaving of wood, which suggests that the wooden rods were probably at least partially manufactured directly at the site. it is also likely that humans removed only small amounts of flesh, without reaching the bones with the tools they used for processing the carcasses. the scattering of the bones in a fairly small area, the total lack of anatomical articulation and the virtual absence of specific kinds of bones, such as vertebrae, basipodial and metapodial bones, and phalanges underscore an apparent skeletal selection. whether this occurred before or after the skeletonization and dismembering of the carcasses is yet unclear. the behavior of extant african hunters (crader, 1983; fisher, 1992) may provide insights into the possible patterns of processing and preferential selection of the elephant carcass parts at poggetti vecchi. in general, the proximal parts of the limb bones (humeri and femora) and the extremities (carpals, tarsals and phalanges) are removed from the carcasses and transported to the villages, where the flesh can be stripped off more accurately and the marrow extracted if necessary. a similar behavior could explain the underrepresentation of basipodial and metapodial bones and phalanges in the poggetti vecchi elephant samples. nonetheless, the voorhies (1969) categories of bones represented at the site indicate that the winnowing action of streaming water could also well explain the very low frequencies of easily transportable elements. at the same time, streaming water may account for the occurrence of the remains of other taxa (bos, cervus, capreolus): these bones, which are quite susceptible to hydraulic transport, are largely abraded or polished. they were therefore likely reworked from uphill areas and are allochthonous for the site. the extensive scratching of the bone and tusk surfaces, as well as by the dominance of dry bone breakage is highly suggestive that the skeletons were trampled over, perhaps repeatedly, by bypassing animals, elephants included. hence, trampling and kicking can account for their disarticulation and scattering, at a time when the bones were already in dry state. finally, the root etching and humic corrosion on many bones are probably associated with plant colonization. poggetti vecchi offers the chance to obtain an unprecedented amount of information on how local early neanderthals interacted with the animals of the time, as well as on how skillfully flexible they were in response to contingencies under the challenging environmental and climatic conditions at the mis 7-6 transition. based on the collected evidence, local human hunters benefited from the large accessibility to concentrated resources unexpectedly made available by the fortunate interplay of palaeobiological, geological and climatic factors. the site thus offers critical information on the behavior of early neanderthals, which is still very imperfectly known. contrary to previous belief, early neanderthals appear to have been particularly skilled to deal opportunistically with environmental and climatic adversities, and able to modify over time the scheduling of their exploiting strategies. acknowledgements the study was financially supported by mazza p. fondo ateneo 2015 miur (the italian ministry of education, university and research). we are grateful to all colleagues and experts involved in the geoarchaeological study of poggetti vecchi site. references behrensmeyer a.k. 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(ed.), animal bones, human societies. oxbow books, oxford, 89-105. villa p., mahieu e. (1991) breakage patterns of human long bones. journal of human evolution 21, 27-48. voorhies m. (1969) taphonomy and population dynamics of an early pliocene vertebrate fauna, knox country, nebraska. university of wyoming contributions to geology special paper no. 1, larmie. 48 ms. received: may 15, 2018 final text received: may 27, 2018 capalbo c. et al. available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 99 103 extinction and paleoecology of the late pleistocene cave bear from northeastern italy: radiocarbon and stable isotope evidence gabriele terlato 1,2 , hervé bocherens 3,4 , matteo romandini 5 , nicola nannini 1,6, keith a. hobson 7 , marco peresani 1 1 dipartimento di studi umanistici, sezione di scienze preistoriche e antropologiche, università degli studi di ferrara, ferrara, italy 2 area de prehistoria, universitat rovira i virgili (urv), tarragona, spain 3 department of geosciences, biogeology, university of tübingen, tübingen, germany 4 senckenberg centre for human evolution and paleoenvironment (hep), university of tübingen, tübingen, germany 5 dipartimento di beni culturali, università di bologna, ravenna, italy 6 muse museo delle scienze, trento, italy 7 department of biology, western university, biological and geological sciences building, london, ontario, canada corresponding author: g. terlato <trlgrl@unife.it> abstract: we present here the chronometric, isotopic and taphonomic evidence of cave bear from three palaeolithic sites in northeastern italy: paina, trene and buso doppio del broion (berici hills vicenza). two direct radiocarbon dates yielded an age around 24 ka bp, which make these remains the latest known representatives of the species in europe and confirmed that demise of cave bear falls during the lgm. the carbon and nitrogen isotopic values of bone collagen do not show any marked ecological change since 33 ka bp, suggesting an essential vegetarian diet. several bear bones preserved traces of human modification such as cut marks, which enables a reconstruction of the main steps of butchering process. keywords: cave bear, extinction, palaeoecology, cave bear hunting, northeast italy 1. introduction the late quaternary witnessed extinction of large mammals in europe. the course and the timing of these events differ from region to region and the causes of these extinctions are the subject of an on-going debate (barnosky et al., 2004; lorenzen et al., 2011; sandom et al., 2014 stuart, 2015). in any case, a better understanding of the mechanisms that led to extinction of several large mammal species in a context of climate instability and changing human impact on the ecosystems will have implications for anticipating possible future extinctions. the cave bear (ursus spelaeus sensu lato) is an interesting species to focus upon because has possibly yielded the largest amount of fossil remains in late pleistocene caves in europe, with a large part associated with human deposits. cave bear bones are often associated with stone tools or with other evidence of human presence, possible interactions between the two species. radiocarbon dating suggests that they went extinct simultaneously in different parts of europe about 25-28 ka bp, close to the onset of the last glacial maximum (lgm) during mis 2 (adams, 2002; hofreiter et al., 2004; wojtal, 2007; blant et al., 2010; münzel et al., 2011; bocherens et al., 2014; martini et al., 2014; sabol et al., 2014; baca et al., 2016). understanding feeding habits of cave bear is essential as it might give insight into those factors contributing to their extinction: whether they were strictly herbivores or more flexible omnivores could have resulted in different scenarios, whereby the relative influence of climate change, human pressure could have played different roles (pacher & stuart, 2009; bocherens et al., 2014a). in this context, herbivorous feeding habits inferred from tooth, skull and jaw morphology (kurté, 1976; münzel et al., 2014; van heteren et al., 2016) as well as the stable isotopic composition of cave bear collagen from a large majority of european sites, ranging from spain to romania, indicate an essentially vegetarian diet (bocherens et al., 1997; 2006; 2011; 2014; vila taboada et al., 1999; grandal-d’anglade et al., 2011; münzel et al., 2011; horacek et al., 2012; pacher et al., 2012; krajcarz et al., 2016; naito et al., 2016). in contrast, δ 13 c and δ 15 n analyses on cave bears from two romanian sites (richards et al., 2008; robu et al., 2013) suggested that some cave bears included a substantial amount of meat in their diet. in this present work, we report the results of such investigation carried out on cave bear bones from three sites: paina cave, trene cave and buso doppio del broion (berici hills vicenza), part of them recently published (terlato et al., 2018). we applied to these bones some techniques that allow us to fit these specimens into a chronological and ecological context and yield further information that help to understand the extinction process of cave bear in this area of the southern alps. 2. material and methods paina cave (units 5 and 6), trene cave (macro-unit b) and buso doppio del broion (units 1and 2) are located in berici hills in northeastern italy. taxonomic, skeletal identifications and preliminary taphonomic analysis of bones assemblage have been conducted and published by nannini and romandini (2015) and terlato et al. (2018). for stable isotope analysis, 49 cave bear https://doi.org/10.26382/aiqua.2018.aiquaconference bones were selected. in addition, 6 moose alces alces bones from the same sites and units were sampled. the δ 13 c and δ 15 n values as well as c:n atomic ratio of bone collagen for 12 bear samples and 4 moose samples from paina and trene caves have already been published in a previous study (terlato et al., 2018). the collagen extraction was performed following bocherens et al. (1997) at biogeology unit of the geoscience department at the university of tübingen (germany). c and n elemental and stable isotope measurements were performed at the lsis-afar stable isotope facility of the university of western university (canada). collagen samples (0.5mg) were weighed into tin capsules and combusted in a costech elemental analyzer coupled to a thermo delta plus xl isotope ratio mass spectrometer operated in continuous flow mode, with helium carrier gas. two standards, usgs-40 and usgs -41 were included for every ten samples and two internal laboratory standards were included to monitor instrument drift and provide a check on accuracy over the course of each analytical session. values of δ 13 c were calibrated to vpdb and values of δ 15 n were calibrated to air. measurement error was ±0.1 ‰ for δ 13 c, and ±0.2 ‰ for δ 15 n. 100 fig. 1 (a) position of the palaeolithic caves in the berici hills considered in this work; (b) localization and details of anthropic traces; (c) δ13c and δ15n values of cave bear and moose. terlato g. et al. 101 3. results taphonomic analysis on cave bear bones from trene cave and buso doppio del broion has revealed human modification traces like cut marks on several skeletal elements, which enables a reconstruction of the main steps of hide recovery and the butchering process (fig. 1). at trene cave cut marks caused by skinning are present on three mandibles of different individuals. a right calcaneus and a third metacarpal show short cut marks, which are sometimes deep and persistent, attesting the early phases of hide recovery or disarticulation. evidence of defleshing and detachment of muscle mass is evident on a right humerus, on a right fibula and on a left radius for which skinning is not excluded. a percussion mark is visible only on a portion of mandible completely burned suggesting a fracturing action in order to extract the marrow and use the same remain as fuel (terlato et al., 2018). at buso doppio del broion traces are around one rib, which refer to defleshing. the cut marks on the metatarsal certainly indicate skinning of the bear. at paina cave, evidence for bear exploitation by humans are rare. this cave may have been rarely inhabited by human groups, while it was repeatedly occupied and for a long time by cave bears, during hibernation and cub nursing (terlato et al., 2018). in all three sites the c:n ratios, %n and %c demonstrated the very good quality of collagen preservation. the δ 13 c values on cave bear ranged from -22.2‰ to -20‰ (paina cave), from -21.2‰ to -19.6‰ (trene cave) and from -21.0‰ to -19.9‰ (buso doppio del broion). the δ 15 n on cave bear ranged from 1.5‰ to 7.2‰ (paina cave), from 2.1‰ to 5.4‰ (trene cave) and from 1.6‰ to 6.6‰. the δ 13 c and δ 15 n values measured for alces alces ranged from -20.2‰ to -19.5‰ and from 2.0‰ to 5.4‰ (fig.1). the ranges of δ 13 c and δ 15 n values overlap considerably for adult bones of cave bears and moose. there are a few exceptions to this pattern: one tooth and one mandible of young individuals from paina cave with high δ 15 n and low δ 13 c values (terlato et al., 2018) and one tibia from buso doppio del broion with high δ 15 n and high δ 13 c values. three direct radiocarbon dates on well-preserved collagen were carried out and two of them yielded dates tightly clustered (tab.1). the conventional age of the phalanx from paina cave is determined as 19,686±54 14 c bp (23,948 to 23,489 cal bp. sample eth-79366: terlato et al., 2018). the radiocarbon age of a humerus from trene cave is measured as 19,948±55 14 c bp (24,220 to 23,795 cal bp. sample eth-79368: terlato et al., 2018). at buso doppio del broion the rib gave a conventional age as 29,001±123 14 c bp (33,597 to 32,844 cal bp. sample eth-79367). 4. discussion and conclusion these dates on cave bear from paina and trene caves, around 24,200-23,500 cal bp, are more recent than others measured in europe and make it the latest known representative of the species. with these dates there is no doubt that the disappearance of cave bear from italy occurred during the lgm (terlato et al., 2018), more or less coinciding with the expansion of south alpine glaciers (monegato et al., 2017). as the glacial expansions fragmented the ranges of many animal and plant species throughout europe, the southern part of the prealps might have preserved isolated and sheltered refugia for cave bears. especially the berici hills represented a kind of refuge area for the plantigrade, with availability of trophic resources and shelters suitable to overcome harsh winter periods, relative to other zones in the lessini mountains or at higher altitude as in the alps (spötl et al., 2017). isotopic data of these cave bears are similar to other cave bear populations, with low δ 15 n values, in the range of herbivores (here alces alces) and lower δ 13 c values as ungulates, here again alces alces. this indicates that cave bears from berici hills did not differ in their dietary habits from the pattern of the species in western and central europe, an essential vegetarian diet (bocherens et al., 2011; 2014; münzel et al., 2011; pacher et al., 2012). however, the δ 13 c and δ 15 n values do not show any obvious ecological change since 33,000 cal bp (radiocarbon data of rib from buso doppio del broion) despite climatic fluctuations, suggesting a strong niche conservatism for this species, leading to a possible lack of ecological flexibility in the lgm. there are a few exceptions to this pattern. two specimens of young individuals from paina cave showed different δ 13 c and δ 15 n values, that may be related to hibernation or nursing signals (terlato et al., 2018). only one specimen from buso doppio del broion has high δ 15 n and high δ 13 c values which reveals a more omnivore diet of a cave bear, if it will be confirmed by dna retrieving. the high δ 13 c values of alces alces, suggest a relatively open environment, but with clearings available (drucker et al., 2010; terlato et al., 2018). a final though on cave bear bones from trene cave and buso doppio del broion concerns human exploitation for meat and hides may have had an impact on the demise of this species. this could possibly reveal continuity in the hunting and subsistence strategies between hunter-gatherers group tab. 1 radiocarbon dates of cave bear from paina cave, trene cave and buso doppio del broion calibrated. cave bear extinction in northeastern italy during a wide span of time, a situation that was probably not favourable to the survival of the species. we can speculate that the combination of climatic deterioration and increasing human pressure could be responsible to the extinction of cave bear in northern italy, and the final extinction of the species since this population seems to have been the last to survive. this scenario is unfortunately very similar to the situation of numerous mammal species nowadays. acknowledgments this research has been promoted and supported by the university of ferrara (far 2016), the veneto region, the mossano municipality and several public and private institutions (fondazione cariverona). we are grateful to dober chalal aldana, dorothée drucker, christoph wißing and susanne münzel (university of tübingen) for technical assistance in the preparation of the bone samples. blanca mora alvarez tessa plint and fred longstaffe assisted with stable isotope analyses performed in canada. references adams b. 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(2007) zooarchaeological studies of the late pleistocene sites in poland. institute of systematics and evolution of animals, polish academy of sciences, pp.189. 103 cave bear extinction in northeastern italy ms. received: may 4, 2018 final text received: may 15, 2018 104 amq61 panarello mietto.pub � �� � �available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 30 (2), 2017, 105-123 can it be an actual human fossil footprint? the "combined method" helps to give an answer adolfo panarello1, paolo mietto2 1 dipartimento di scienze umane, sociali e della salute, università degli studi di cassino e del lazio meridionale, cassino (fr), italy 2 dipartimento di geoscienze, università degli studi di padova, padova, italy�� � corresponding author: a. panarello <adolfo.panarello@unicas.it>� abstract: recent technological improvements and the growing precision of surveys and analytical procedures together with the growing interest in hominid palaeoichnological traces demand verification of all track-like impressions, especially those which are supposedly human. strict analysis and objective interpretations are increasingly necessary for those hollows which have been too hastily recorded as actual human footprints. in some specific environments, such as quarries or other archaeological sites which have been and are still being continuously altered by natural agents (such as eustatic movements, or weathering/aeolian phenomena, or geochemical processes), the number of structures which mimic the shape of human footprints is incredibly high and can lead to false interpretations. here we try to improve a successfully used method to re-analyze and reject the actuality of the supposed human fossil footprints from the valsequillo basin (mexico) by combining it with well-known and tested forensic methods of gait analysis. we think the new method that we are calling combined method (cm), enables scientists to gain a better understanding of wether a hollow on the ground can actually be a human footprint or not, even in cases where not all its contour details or anatomical landmarks are preserved or recognizable. keywords: human ichnology, human footprints, pseudo-track analysis. 1. introduction a simple glance at the world-wide hominid palaeoichnological record is sufficient to realize that only a few sites are scientifically studied and exhaustively documented. other sites are only known through some folk tales or brief mentions in some papers (avaleyraarroyo de anda, 1950; houck et al., 2009; lockley & roberts, 2004; lockley et al., 2008; lockley et al., 2009; lockley & rodríguez-de la rosa, 2009; quevedo-lara, 1998; rodríguez-de la rosa et al., 2004; rodríguez asensio-noval fonseca, 2012: 226). furthermore, many other ichnological and/or palaeontological sites such as terra amata (de lumley et al., 2011; goudet-ducellier, 1987; hadingham, 1985), happisburg(ashton et al., 2014), vértessz�l�s (fluck, 2011; kretzoi&dobosi, 1990; bridgland et al., 2006; visy et al., 2003), sierra tarahumara (inah, 2011), kenfig sands (bennett et al., 2010), rhodes island (bromley et al., 2009; milàn et al., 2005) and bakala region (marquer, 1960) are still enveloped by a dense cloud of doubts about their validity as actual human ichnosites. for these reasons an objective revision of the most ambiguous evidence and unsatisfactory documentation available has made the necessity arise to have a final, complete and scientifically based hominid-palaeoichnology record. the mentioned necessity became stronger after the well-known episode of the valsequillo basin (mexico) where some depressions in the ground were first interpreted as human and animal footprints (gonzález et al., 2006a, 2006b) and then after further studies, they were shown to be just simple signs left by quarrymen using metallic tools within a quarry area (morse et al., 2010). the scientific method used to prove and reject the mistaken interpretation was elaborated by a team (morse et al., 2010; morse, 2010) taking their stand on the fact that the most important anatomic landmarks of the human foot, although influenced by the structure of the middlefoot and/or by the nature of the ground, cannot significantly change their position from the areas of maximum plantar pressure located within the footprint area. such positions, as well known, match those in which the depressions on the ground are deeper, i.e. in the areas corresponding to the heel, to the heads of the metatarsal bones i and ii and to the hallux. the method by morse et al. was very innovative because it is based on baropodometric observations and frees any analysis from the strict positioning of anatomical landmarks of the human foot (which are not always visible or preserved) in some fixed geometrical positions and focuses on the relative depths inside footprints, which must be coherent with the displacement vectors of body-weight during walking. moreover, the deepest zones are enclosed by the contour of the footprint and can be included within an ellipse inscribing the complete foot. in the new scheme of evaluation, 5 main proposed landmarks also seems to go over some eventual trackmaker's deformations capable of misleading scientists (morse et al., 2010). how� � �� � � 106 panarello a., mietto p. ever, such a technique to verify human footprints can be applied only on «any potential footprint that would be considered complete, that is heel to toes, without regards to its anatomical definition» (morse et al., 2010). here we try to go beyond this limit and to improve the mentioned method by trying to make it applicable to each footprint-like hollow. for this purpose we elaborated a new method, called "combined method" (cm), by combining the described technique with other methods of analysis which have proved successful in forensic environments and which appear easily applicable, i.e. those by wilkinson et al. (1995), kennedy et al. (2003) and berge et al. (2006). 2. the combined method (cm) although based on the same basic principles of the method elaborated by sarita amy morse and her colleagues in 2010 (morse et al., 2010), the "combined method" (cm) (fig. 1) is an improvement as it has fewer limitations and can be applied to each depression on the ground, even when its contour is not completely preserved. furthermore, although with different degrees of approximation, the cm permits the creation and management of a longitudinal axis of the imprint which can be aligned to the major axis of the ellipse designed by the same morse et al. 's method even when its proximal and/or distal margins are lost. in this way the ellipse including the imprint (emor) can be oriented so that it matches the actual orientation of the potential human footprint and this enables the deepest zones to be located more precisely. moreover, as the cm can also be applied to some borderline cases each depression can be contextualized within a gait pattern by identifying a well-defined line of progression. the sharpness of the cm is directly proportional to the amount of available and visible details inside the potential footprint, but it always permits the determination that if at least the hollow can be compatible or not with an actual human footprint. finally, the emor can be divided into further subsets, which are very useful to identify and to analyze some diseases of the trackmakers' foot (panarello, 2016). the following is an explanation on how the cm works. after having checked if the hollow to be studied is located on the former surface of a stratigraphic layer, if all of the geological, chronological, taphonomic and morphostructural conditions of compatibility are fully satisfied (panarello et al., 2017), it is possible to begin the application of cm by tracing all the visible details of the potential human footprint and locating at least two notable points both on the lateral and medial side. such points must indicate the widest and the narrowest part of hypothetical footprint's contour. the same points will be indicated as am and al if referred, respectively, to the medial and lateral tips of the hypothetic forefoot (ball zone) and as tm and tl if referred, respectively, to the medial and lateral tips of the hypothetic hindfoot (heel zone). this allows for an initial basic evaluation of the depression because in an actual human footprint amal is always a greater value than tmtl. if the entire contour of the foot is visible it must be traced according to the scheme by kennedy et al. (2003) marking the convex hull of the footprint, i.e. the complete contour of the footprint without toe impressions. so am and al will match respectively, the medial and lateral edges of the ball corresponding to the heads of the 1st and the 5th metatarsal bone. in the same way, tm and tl will respectively match, the medial and the lateral edges of the heel. as a consequence amal corresponds to the max width of the forefoot and tmtl is to the max width of the heel. by continuing to apply kennedy et al. 's method (kennedy et al., 2003) we can draw the medial tangent (tanm) to the contour passing through am and tm and the lateral tangent (tanl) to the contour passing through al and tl. such tangents intersect at a point outside the footprint, which is located behind the heel. the bisector of the angle between tanm and tanl is the longitudinal axis (lax) of the footprint. lax is the real axis of the footprint when its complete contour is visible and it generally fig. 1 the combined method scheme (reworking and combination from wilkinson et al., 1995; kennedy et al., 2003; morse et al., 2010). � �� � � 107 the "combined method" to validate human footprints passes through 2nd and 4th toe in a normal foot (d’août & aerts, 2008). when the contour of the footprint is not completely preserved, lax must be considered as a virtual axis, which is fully working in the cm, as it never falls out of the zone closed by the 2nd and the 4th toe even when it cannot fully express the angular reality. in fact, it does not distort the cm scheme since it is not based on specific anatomical positions but rather on areas of compatibility. taking into account that the heel-strike is the detail which is almost always present in a human footprint, we thought of choosing it as a basic landmark, its rearmost point crossed by lax as indicated by x. finally, the line crossing x and normal to lax was considered as the base-line and indicated by bl. the next steps are the correct positioning of the major axis of the emor so that it matches the lax and specifies the length of the major axis. a further step is to place a variant of the rectangular and tripartite grid (rewil) used by wilkinson et al. (1995) and by mccrory et al. (1997) in their methods. several cases may arise: case a (at least the longitudinal contour of the footprint is visible, with or without the imprint of the hallux) (fig. 2) this is the luckiest case, because it is very easy to identify the lateral and medial edges, to draw the corresponding tangents, to identify x and bl and to place the lax making it coincide with the major axis of emor. the only problem to solve is determining the length of the major axis of the emor. if the imprint of the hallux is preserved it is easy to draw the rewil by placing one of its bases on the bl and by drawing the other parallel base in such a way that it passes through the most distal point of the footprint which is clearly identifiable on the frontal tip of the hallux. if the imprint of the hallux is not preserved we can determine an approximate major axis length by searching for it among the values in table 1 or taking into account the dimensional proportions of the foot as indicated by the lengths of the tarsal, metatarsal fig. 2 samples of footprints related to case a. � �� � � panarello a., mietto p. and phalangeal bones. such dimensions are, respectively, 51%, 26% and 23% of the total foot length. in australopithecus afarensis, the same proportions are, respectively, the 38%, the 32% and the 30% of the total foot length (klenerman-wood, 2006: 49; tuttle at al., 1991b). the dimensional values in table 1 refer to hominids of which at least one fossil footprint has been discovered, measured and verified as actual. of course, such selection must be made strictly taking into account the chronological age of the potentially trampled surface. case b (heel-strike imprint is visible but the distal margin of the footprint isn’t preserved) (fig. 3) in this second case, while positioning the cm elements, we should take into account that only the heelstrike zone must be considered and a triangle must be identified by placing its vertices in the most lateral point, in the most medial point and in the rearmost point, which must be considered as x. the bisector of the angle whose vertex is x must be considered as lax. the length of the major axis of the emor can be determined by using table 1 as in the case a. also the tripartite schemes used by wilkinson et al. (1995) and by mccrory et al. (1997) can provide great help in deterfig. 3 samples of footprints related to case b. 108 tab. 1 reference lenght and width of the fossil human foot for the definition of the longitudinal axis in the combined method (cm). � �� � � the "combined method" to validate human footprints mining the length of the major axis of the emor. then the rewil might be positioned taking into account the values in table 1. such dimensional values, refer to hominids of which at least one fossil footprint has been discovered, measured and verified as actual. of course, each choice must be made strictly taking into account the chronological age of the potentially trampled surface. for a wider dimensional range of the foot of contemporary homo sapiens, the huge study by howard v. meredith (1944) can be referred to. it must be taken into account that in the case b the degree of approximation of cm is wider. case c (at least one toeprint is visible but the proximal margin of the footprint is not preserved) (fig. 4) this third case is substantially similar to the second one since the preserved parts are only inverted, but the previously described procedure can be applied only if at least one of the preserved toe prints is the hallux. in such a fortunate case, it is sufficient to invert the procedure of case b by starting from the tip of the hallux to create all the other geometric elements. on the contrary, if only the 2nd and/or the 3rd toe prints are preserved, it is much more difficult to identify all the other elements of the cm since we are in a situation of extreme approximation. in fact, the details of the impression preserved are so few that it is really difficult to find reliable information about both its ichnological reality and/or about its precise location in a gait pattern. in what remains of the imprint only a square-ruler can be applied whose longer side is tangential to the most lateral contour of the toe 2nd or to the most medial contour of the toe 3rd, the shorter and horizontal side of the same square ruler being tangential to the most distal limits of the toe prints. although with a wide margin of approximation, the vertical side of the square ruler can be considered as lax, so that it is possible to proceed to the application of the values in the table 1 and to go on to identify the x and the bl. when only a few anatomical details are visible, the tripartite scheme used by wilkinson et al. (1995) and by mccrory et al. (1997) can be a great help in determining the length of the major axis of the emor. measurement and analysis by the cm isolated footprints or potential footprint in which even less details are preserved should not be attempted. case d (both proximal and distal margins of the contour are not visible; only a few traces of the contour are preserved) (fig. 5) this is the most complicated case to be analysed as the amount of available detail is poor. as a consequence it is also the case in which the obtained data are mostly approximate. however the main purpose of cm is to make emor most widely applicable and even in this situation it does not seem substantially altered, but let us see how to proceed. in the footprint area we must consider as am and tm, respectively, the most medial edges of the preserved contour of the ball-zone and the heel-zone. similarly, we must consider as al and tl, respectively, the most lateral edges of the preserved contour of the ball-zone and of the heel-zone. 109 fig. 4 samples of footprints related to case c. � �� � � this makes us able to draw a convex hull of the potential footprint and to determine its lax as already carried out in case a. both of them, though approximate, do not significantly alter the framework of the depressions inside the footprint area. so, it is sufficient to draw the perpendicular to lax passing through the rearmost point of the heel-zone to identify point x. now we can use table 1 to determine the length of the major axis of the emor and, consequently, all the other necessary details of the cm scheme. as in preceding cases an additional aid can be given by the tripartite scheme used by wilkinson et al. (1995) and by mccrory et al. (1997). case e (no part of the contour is preserved; only a displacement rim is visible) in this last case we must be fully aware that we are working on the extreme border of reality and that the only instance in which we analyze the potential footprint is in the presence of a displacement rim in its total structure. such a rim, as well-known, can be created only by trampling a surface that has yet to be solidified. nevertheless we must be extremely prudent while analyzing details taking into account that the displacement rim could mean only that the same hollow is a true imprint and not also that it is an actual human footprint. of course, if the footprint-like depression is coordi�nated into a gait pattern the possibility of it being an actual footprint increases significantly. to apply the cm we inscribe the general hollow marked by the edge of the expulsion rim in the most narrow rectangle that can contain the entire depressed area. so the middle longitudinal line of the rectangle can be considered as the lax and its length matches the major axis of the emor. of course, the bl is the base of the same rectangle. as above, here too we can apply the tripartite scheme used by wilkinson et al. (1995) and by mccrory et al. (1997) to determine the length of the major axis of the emor. on the basis of the described geometric constructions 5 basic landmarks should be identified: landmark 1: the point of coincidence on the baseline (bl), between the rearmost point of the heel and the lowest point of the major axis of the emor. landmark 2: the highest point of the major axis of the emor located on the parallel to the base-line tangent to the distal point of the most protruding toe print. landmark 3: the point of intersection between the parallel to the base-line passing through the midpoint of lax and the lateral contour of the footprint. landmark 4: the point of intersection between the parallel to the base-line passing through the midpoint of lax and the medial contour of the footprint. landmark 5: the point of maximum pressure inside the footprint area. 3. in-field experiments although the cm is substantially a winning combination of methods (wilkinson et al., 1995; kennedy et al., 2003; berge et al., 2006; morse et al., 2010), which have been widely and successfully tested, we think that some supplementary specific experimentations in the field of the cm can be useful to verify its reliability and also to show its limitations. for this purpose, we selected two trackmakers (an adult male and an adult female) with known anthropometric characteristics and diseases and we let them walk along different substrates without conditioning their normal walking. the male trackmaker walked on a sandy ground, while the female walked on uneven and chaotic matter made up of mud and gravel, and on another surface consisting of a cement mixture. then we surveyed the footprints they left and we analyzed them by cm. in all three cases the depth areas inside the footprints were found in the expected sectors of the emor. moreover, in the case of the female trackmaker, the analysis of the contour lines of the footprints allowed us to detect and to highlight the disease for hallux valgus she had already declared. all examined footprints proved that cm always works but also pointed out that the variability of the substrate can heavily affect the dimensional range of the same footprints. this suggests extreme caution while making any estimation about the body of the trackmaker starting from his fossilized footprints. finally, we successfully tested the combined method on an actual human fossil footprint, which has 110 fig. 5 samples of footprints related to case d. panarello a., mietto p. � �� � � � been dated around 350 ka b. p. (mietto et al., 2003; avanzini et al., 2008). the photogrammetric measurements were taken using an slr camera canon eos 550d equipped with lens canon ef-s 18-200 mm and a compact camera canon powershot g9. developments, measurements and calculations of three-dimensional models, as well as maps derived therefrom, were made using the software agisoftphotoscanprotm (ver. 0.9.0 build 1586) and kitwareparaviewtm (ver. 3. 98.1.64) and the details of each photogrammetric model are shown in table 2. we think that the field experimentations we present here are good examples to show that cm is effectively able to reveal if a hollow on the ground can be an actual footprint or not. furthermore, the cm proved effective in any weathers and is capable of revealing some deformations of the foot if present. sea sand the experiment was carried out in a place of the tyrrhenian shore at scauri, a small city located in central italy (province of latina; n41° 15.010'e13°42,941') (fig. 6). the trackmaker (b.f., male, aged 54, 1,65 m tall, and 66,5 kg weight) said he had suffered some years ago from a double fracture of the left anklebone with detachment of the cartilaginous joints. during the experimentation, he walked barefoot for a distance of 8 meters. the footprints he left were 14, of which 7 relate to the right foot and 7 to the left foot. the data concerning the gait, however was measured only in the central part of the trackway and refers to the tracks from 5 (left) to 8 (right) (fig. 7, fig. 8), in order to avoid any additional variables due to acceleration or deceleration. the average measured stride is approximately m. 1,175. the average length of the measured foot is m. 0,27. the average width of the track is about 38 cm. the estimated stature measured starting from footprints’ dimensions almost perfectly matches the effective one by applying a ratio of 16,4%, which is in perfect harmony with an extremely pliable substrate that guarantees that the footprint is dilated both in length and in width compared to the actual size of the foot. sea sand, which is composed of very fine grains, has proved to the most receptive substrate, capable of preserving a detailed impression giving exhaustive anatomical and biomechanical data. the details are more evident in 111 tab. 2 parameters of the photogrammetric models. fig. 6 scauri beach (central italy) location of the experiment on sea-sand (trackmaker: b.f., male). � the "combined method" to validate human footprints � �� � � � 112 fig. 7 experiment on sea-sand: the analysed footprints among those left by the male trackmaker b. f. (a: zenithal photography; b: contour lines (1mm); c: depth map). panarello a., mietto p. � �� � � this creates a very pronounced discontinuity between the distal part of the forefoot (which assumes precisely the rounded shape of a pillow) and the proximal part the toe depressions, which are aligned with the hallux depression along an anteromedially oriented direction. finally, the foot angle, i.e. the angle measured between the tread and the axis line of progression, shows that the places where marine sand also has slightly slimy component. it is also very interesting to note that a large amount of sand is pushed up corresponding to the medial longitudinal arch area and this makes evident that body balance while walking is searched and found in the lateral area of the foot. the backwards movement of the toes is also evident as they try to grip the ground and 113 fig. 8 experiment on sea-sand: details of the four considered footprints. fig. 9 experiment on sea-sand: the combined method applied on the considered stretch of trackway. the "combined method" to validate human footprints � �� � � left foot (18°) is more everted than the right (16°), which could be reminiscent of the trauma fracture in his left foot, which, although it has perfectly healed, may have left a trace in the gait pattern. finally, in all of the footprints, which are magnificently preserved, all the characteristics of the human foot are fully recognizable, i.e. 1) a wide and well-rounded heel pad; 2) a wellshaped, narrow and raised medial arch; 3) a welldefined forefoot with a well characterized ball; 4) the presence of occasional ridges proximal to the positions of the heads of the 1st and the 2nd metatarsal bones; 5) maximum extension in the distal zone of the ball pad which is rightly located in correspondence of the position of the 2nd toe; 6) well defined and separated impressions of pad and tip of the hallux; 7) well defined impressions of lateral toes (meldrum et al., 2011). specifically referring to the cm application, all the landmarks are in their correct position (fig. 9). cement mixture the experimentation was carried out during the casting of a pavement, on a specially leveled surface (fig. 10). the substrate was composed of a mix with a very high percentage of cement, enriched with potassium and a plentiful quantity of river gravel. the experiment was carried out in the rain so the degree of wetting was very high and gave the consistency of an almost muddy matter with continuous collapse of the sidewalls of the footprints after a lifting of the foot. the trackmaker was a female (s.m.z., 45 years old, 1,52 m tall and 55 kg weight) who is suffering from hallux valgus on both feet. during the trial, she walked barefoot along a distance of 10 meters on an almost planar and extremely yieldable ground. she left a total of 17 footprints (8 relate to her right foot and 9 relate to her left foot). however, to avoid any bias from braked or accelerated gait, all data was recorded only in the central part of the trackway and refers to the footprints from 6 (right) to 9 (left) (fig. 11). the average stride measured is approximately m. 1,10. the measured average length of the foot is about m. 0,20. the estimated stature starting from the footprints’ length almost perfectly matches the effective one if we apply a 13,2% ratio. this is easily explainable if we consider that the soft matter of the substrate always collapses inside of the impression after the foot pressure and its consequent lift which causes extremely irregular contours and frames which, in any case, are less long and/ or less wide than the real ones. the average angle of the left foot, with respect to the line of progression, is equal to 6,5° while the average angle of the right foot is equal to 7,5°. the average measured width of the track is about 25 cm. it is worth nothing that only footprint n. 6 and n. 7 are completely and objectively measurable. the footprint n. 6 (right foot) (fig. 12), although narrow and elongated, preserves an evident medial concavity, which has its own center in the central third of the total length of the footprint. furthermore, if we apply the emor on it (fig. 13), we can notice that the landmark on the key of the vault of the medial longitudinal arch fully respects the criterion of berge et al. (2006) as it falls in a higher position than the forefoot and the rear foot impressions. finally although partly covered by the collapse of the medial wall of the cavity it is clearly visible, within its contour, the protrusion of the 1st metatarsal head. also on the lateral side, the movement towards the intermodal soft wall has reduced the width of the midfoot, but has not completely erased the anatomic details of the human foot. the forefoot, as was logical to be expected, is evident, as well as the most proximal part of the depression of the hallux. another important specimen is the footprint n. 7 (left foot) (fig. 12), which is the clearest and most readable one. it has an extended displacement rim, which is more evident on the lateral margin. here the sidewalls 114 fig. 10 location of the experiment on cement mixture (trackmaker: s.m.z., female). � � �� � � � 115 fig. 11 experiment on cement mixture: the analysed footprints among those left by the female trackmaker s.m.z. (a: zenithal photography; b: contour lines (1mm); c: dept-map). � �� � � fig. 12 experiment on cement mixture: details of the two best surveyable footprints among the four considered ones. � � 116 � fig. 13 experiment on cement mixture: the combined method applied on the considered stretch of trackway. panarello a., mietto p. � �� � � had only minor failure meaning every detail of the shape of the foot is well recognizable. the footprint inclusion within the emor diagram has further highlighted the correct anatomical position of maximum pressure areas and so the impressions of the heel and the forefoot with the hallux and 2nd toe are very evident. medially, likewise the protrusion of the head of the 1st metatarsal bone is very evident, confirming disease of hallux valgus as declared by the experimental trackmaker before starting her walking. within the footprints n. 8 (right foot) and n. 9 (left foot), the details are less clear so that the emor is not easily fixable. however, in both cases the areas of maximum pressure are evident inside the footprint and are located in the third medial distal part. such evidence is fully compatible with those of the same kind which are better preserved in the other footprints (fig. 13). finally, the frameworking within an ichnological pattern respecting human gait-standard is clearly constructible as one could expect since the trackmaker is definitely human. mud and gravel the experiment was carried out on a small area created by the outflow of precipitated waters during heavy and prolonged rainfall. the transported debris are laid on a thick muddy bottom, creating a composite matter, which is muddy and extremely plastic in depth and has an uneven, porous and grainy surface. the emplaced layer is about 9 cm thick, while its grainy surface is only a few millimeters thick (fig. 14). we chose this kind of deposit to analyze the response of such a chaotic matter to foot pressure during walking. the trackmaker is the same used for the experiment on cement mixture (smz, female, 45 years old, 1,52 m tall, 55 kg weight, with a declared disease from hallux valgus on both feet) and she walked barefoot along a stretch of about 3 meters, leaving 7 footprints (4 relate to the right foot and 3 relate to the left foot). as in previous cases, to minimize the distortion due to an eventual mental conditioning for the initial acceleration and the final braking, only four footprints in succession have been considered, that is the most central ones, from the footprint n. 3 (right) to the footprint n. 6 (left) (fig. 15). the average angle of the left foot, compared to the line of progression, ranges from -2° to -5° revealing a tendency to introflex the foot overcoming the line of progression, perhaps forcing the pronation in the search for balance during walking on such unstable ground. on the contrary, the average angle of the right foot is quite constantly 4°. the average width of the tracks is about 18 cm. the average measured stride is approximately m. 0,73. the average length of the measured foot is about m. 0,21. the estimated stature starting from footprints length almost perfectly matches the actual one by applying a 13,8% ratio. also in this case, the extremely yieldable substrate influences the actual size of the prints, but without erasing the anatomical features of the foot. the footprint n. 3 (right foot) (fig. 16) is very light as it was left in an small area where the mud layer was thinner. although the displacement rim is barely perceptible in the lateral side area, the hollow of the forefoot is perfectly recognizable and clearly shows the declared disease from hallux valgus on both feet. the cavity of the hallux is also easily recognizable, especially in its proximal part. the footprint n. 4 (left foot) (fig. 16) is recognizable in all its parts and preserves the signs of high pressure in the forefoot area, especially in correspondence with the head of the 1st metatarsal such highlighting the mentioned disease from hallux valgus. in addition within the footprint n. 4 area a strange accentuation of depth in the medial side of the ball is also evident. this is due to the major pliability of the ground at that point that was instinctively compensated by the trackmaker with a more pronounced anteromedial pronation. footprints n. 5 (right foot) and n. 6 (left foot) (fig. 16) are those which preserve the clearest anatomic details of the human foot and in both of them, the depressions of the heel, medial longitudinal arch, forefoot, toe depressions and big toes were perfectly identifiable. the footprints n. 3 and n. 5 are slightly introflexed with respect to line of progression, but they do not show a significant depth in their medial distal area. this is due to greater compactness of the ground at that point and also to a more secure and steady pace. finally, both footprints show evidence of hallux valgus, represented by a pronounced protrusion medially oriented of the ball in correspondence of the head of the first metatarsal bones. also on this very heterogeneous ground all fixed 117 fig. 14 detail photo of the matter used for the experiment on mud and gravel (trackmaker: s.m.z., female). � the "combined method" to validate human footprints � �� � � � 118 fig. 15 experiment on mud and gravel: the analysed footprints among those left by the female trackmaker s.m.z. (a: zenithal photography; b: contour lines (1mm); c: dept-map). panarello a., mietto p. � �� � � landmarks fall in the correct anatomic areas within the fixed emor (fig. 17) finally, we must observe that the length of the step and of the stride seem to be influenced more by a sort of consciousness of the brevity of the walkable route than by the instability of the ground. actual human fossil footprint we also applied the combined method on one of the so-called “ciampate del diavolo” (“devil’s trails”), i.e. on one of the well-known actual middle-pleistocene human footprints found on the north-eastern slope of the roccamonfina volcano (central italy) (mietto et al., 2003; avanzini et al., 2008). 119 fig. 16 experiment on mud and gravel: details of the four considered footprints. fig. 17 experiment on mud and gravel: the combined method applied on the considered stretch of trackway. the "combined method" to validate human footprints � � �� � � we chose for this purpose the footprint a25, which is one of the best preserved and we were soon able to observe that also in this case the cm works very well. in fact, although the footprint is located on a steep slope, all the cm landmarks fall in their correct positions so confirming what we already knew, i.e. that the considered footprint was left on a soft slope by a right foot of an our ancestor who lived around 350 ka b.p. (scaillet et al., 2008; santello, 2010). within the footprint's contour and using the cm scheme the imprints of the heelstrike zone are clearly visible, like those of the medial longitudinal arch, forefoot and hallux. all of them match perfectly with the anatomic landmarks where one would expect to find them (fig. 18). 4. discussion and conclusions the schemes and landmarks of the combined method allow us to scientifically evaluate the precise positions of the most depressed areas within the emor area according to morse et al. 's method (morse et al., 2010) and according to the anatomical features of the human foot. it is widely known that the depressions on the bottom of a human footprint can perfectly reproduce the movements of the lower limbs and mainly of the feet during a gait cycle, therefore we should expect to localize the deepest area of the foot in the geometrical zones which the body weight passes through in order to able to say that a depression is an actual footprint or not. specifically, the deepest depressions must be located at least in the heel-strike zone, in the zone of the heads of the 1st-2nd metatarsal bones and in the hallux zone (day & wickens, 1980; schmid, 2004; meldrum & hilton, 2004; klenerman & wood, 2006; raichlen et al., 2010; morse et al., 2010; bennett & morse, 2014; meldrum et al., 2011; dingwall et al., 2013). so it is very important that after the application of the cm at least the landmarks 1 and 5 do not fall, respectively, outside quarters 2-3 (both of the feet) and outside quarter 1 (left foot)/ quarter 4 (right foot) of the emor. similarly, landmark 4, which corresponds to the vault of the plantar arch, has to be always at a higher level than those of all other landmarks as well pointed out by berge et al. (2006). if some disease or malformation of trackmaker's foot is supposed, it must be present in more than one imprint of the same foot before it can be considered as authentic (morse, 2013; bennett & morse, 2014; panarello, 2016 and quoted bibliography). finally, we think using the combined method, which is a combination of other already known and welltested methods, is a significant breakthrough and certainly be considered as an important improvement. it is 120 fig. 18 roccamonfina footprint "devil's trails" a25 (a: zenithal photography; b: solid surface; c: contour lines (1 mm); d: depth map; e: depth map with emor applied). panarello a., mietto p. � �� � � clearly evident, its easiness of application and its capacity to be applied practically to each hollow or depression on the ground, even to those in which no anatomical detail is visible. as it is based on the depressions created by the displacement substrate as the human foot ambulates on a soft ground, it is closely linked to the anatomy of the human foot. the cm is free from strictly located positions of the anatomic features of the foot within the bottom of the footprint and is more closely linked to the motion vector of center of mass and of body weight during the gait cycle. perhaps the cm alone is not able to say if a depression on the ground is an actual footprint or not, but it is certainly able to say if the depression is not an actual footprint and/or if it is at least compatible with a human footprint. the cm is much more accurate and useful if applied to successions of potential footprints together with other methods for the analysis of the human gait (as, for example, that of wilkinson et al., 1995). moreover, the cm becomes precious if associated with other stratigraphical, palaeontological, chemical, archeological and anthropological methods for evaluating the potentially ichnological sites and it also lends itself to pointing out some recent natural and anthropic contaminations and/ or alterations of the most ancient traces. acknowledgements we are very grateful to mr. b. f. and mrs. s.m.z. for having made possible the experiment on field with their great patience and willingness. we also thank mr. pasquale de fusco and mr. angelo salvucci for their precious help during the experiment on cement mixture. we are also very thankful to maria rita palombo, andrea sposato and the anonymous reviewer, for their precious comments and suggestions that increased the quality of the manuscript. finally, we would like to thank ms maria palumbo and ms teresa gray for their linguistic check. references avanzini m., mietto p., panarello a., de angelis m., rolandi g. 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(1995) the measurement of gait parameters from footprints. the foot, 5, 84-90. 123 ms. received: november 28, 2016 final text received: june 13, 2017 the "combined method" to validate human footprints � �� � � � 124 amq abs marino et al palcom 151-154.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 151 154 the climate variability during marine isotope stage 19: evidences from a west-east mediterranean transect maria marino 1, franck bassinot 2, adele bertini 3, salvatore gallicchio 1, angela girone 1, timothy herbert 4, patrizia maiorano 1, sebastien nomade 2, paola petrosino 5, ornella quivelli 1, teresa rodrigues 6, francesco toti 3, neri ciaranfi 1 1 dipartimento di scienze della terra e geoambientali, università degli studi di bari, bari, italy 2 laboratoire des sciences du climat et de l’environnement, gif-sur-yvette, france 3 dipartimento di scienze della terra, università degli studi di firenze, firenze, italy 4 department of earth, environmental & planetary sciences, brown university, providence, usa 5 dipartimento di scienze della terra dell'ambiente e delle risorse, università degli studi di napoli federico ii, napoli, italy 6instituto portugues do mar e da atmosfera, lisboa, portugal corresponding author: m. marino <maria.marino@uniba.it > abstract: new high temporal resolution data on calcareous nannofossil and planktonic foraminifera assemblages, alkenone-derived sea surface temperature and stable oxygen and carbon isotopes are acquired on the montalbano ideale section (southern italy) and at the ocean drilling program (odp) sites 975 and 976 through marine isotope stages (mis) 20-18. results describe accurate climate pattern and distinct orbital-suborbital up to millennia-scale oscillations across the investigated interval. keywords: mis 19, calcareous plankton, sst, pollen, stable oxygen and carbon isotopes, mediterranean 1. introduction mis 19 is the mid-pleistocene interglacial considered the best analogue of mis 1 due to their similar orbital configuration (extraordinarily low eccentricity and obliquity maximum close to the precession minimum) and (paleo)climate signal (tzedakis et al., 2012). a strong likeness between the climate trends through termination ix (i) and the onset of full interglacial 19 (1) has been recently suggested (maiorano et al., 2016) based on marine and terrestrial biological proxies at the inland marine succession of montalbano jonico. several issues are however still debated, mainly concerning i) the beginning of mis 19, as recorded by oxygen isotope records or biological proxies, ii) the duration of mis 19c (full interglacial), iii) the mode and timing of glacial mis 18 inception. with the aim to improve the comprehension of climate evolution through this crucial time interval, which includes the chronostratigraphic boundary of the lower-middle pleistocene, new investigations are carried out on the montalbano jonico section (southern italy). it is a continuous reference succession for the lower-middle pleistocene transition spanning mis 37-16 interval. in particular, the ideale partial section yet relies on an exceptional multi-proxy high-resolution data set across termination ix to the inception of mis 18 (fig. 1a) (maiorano et al., 2016). the authigenic 10be/9be data (simon et al., 2017) and 40ar/39ar age for tephra layer v4 (773.9 ±1.3 ka, petrosino et al., 2015) at the mis 19c/19b transition in the ideale section (fig. 1a) represent additional invaluable stratigraphical constraints within the matuyama-brunhes transitional period. moreover, new studies are performed at the western mediterranean odp site 976 (alboran sea) and site 975 (algero-balearic sea) (fig. 1b) in order to have a westeast record of the climate variability during mis 19 in the mediterranean basin. 2. material and method the montalbano jonico ideale section (southern italy) is 74 meters thick and consists of dark-light grey silty clays. the sediments from the odp sites 976 and 975 consist of nannofossil and foraminifera-rich clays. high-resolution quantitative analyses were performed on calcareous plankton assemblages, in the same samples used to measure the new stable oxygen and carbon isotope ratios carried out on melonis barleeanum and cassidulina carinata at the montalbano jonico section, and on globigerina bulloides at the sites 975 and 976. isotope analyses at the site 975 are still in progress whereas alkenone analyses were performed at the balearic core as well as at the montalbano jonico ideale section with the aim to obtain high-resolution sea surface temperature (sst) and signals of terrestrial molecular biomarkers strictly linked to climate on land and hydrological setting. https://doi.org/10.26382/aiqua.2018.aiquaconference 152 marino m. et al. fig. 1 a) main chronological and environmental constraints at the montalbano jonico ideale section. pc1 curves represent factor 1 obtained by principal component analysis performed on planktonic foraminifera and calcareous nannofossils, and on benthic foraminifera. b) location map of the study successions. 153 3. results an original astronomical tuning of the δ18o record, adjusted by the radiometric dating of tephra v4, is performed at the ideale section, using the strong analogies between mis 1 and mis 19c in terms of orbital forcing and co2 level (nomade et al., submitted). the overall results reveal a distinct climate pattern of mis 19c and at least three millennial-scale oscillations (ii-iiii, fig. 1a) superimposed on the long-term drying and cooling trend leading to mis 18 taking place in one single precession cycle, suggesting a non-linear response of western mediterranean climate to orbital forcing during this period (i.e. mis 19a). results from site 976 and site 975 (fig. 1b) further improve the knowledge on the mode and timing of the climate phases during mis 20-18. in detail, the δ18o records from the deep sea undisturbed sections clearly depict stages and substages, and stadial and interstadials, which are in excellent agreement with climate oscillations documented by the isotope and biological data at the montalbano jonico ideale section. key taxa of calcareous plankton assemblages record distinctive patterns that are mainly related to sea-surface water temperature changes and to water exchange rates between atlantic ocean and mediterranean during glacial (mis 20)-interglacial (mis 19) phases and short-term climate episodes at the termination ix. variations in turbidity and salinity as well as mixing and stratification or nutrient content in the sea surface waters have been reconstructed based on the pattern of selected coccolithophore and planktonic foraminifera taxa. among pollen assemblages, the mediterranean/temperate broad-leaved deciduous forest taxa exhibit higher abundances during interglacials and interstadials (bertini et al., 2015) when warm-water calcareous plankton taxa increase (fig. 1a). while, the expansion of steppes and semi-desert vegetation cover, as well as the incursion of polarsubpolar calcareous plankton taxa, occur during cooler periods possibly associated to atmospheric and north hemisphere ice-sheet dynamics. shorter-lived climate changes are also detectable at the millennial time-scale. in the montalbano ideale record, unequivocal evidence of the shallow water analog of ghost sapropel i-cycle 74 (784 ka) has been documented based on minima in δ13c and δ18o, and the occurrence of planktonic and benthic invertebrate taxa indicating water column stratification and oxygen deficiency at the sea bottom (maiorano et al., 2016; nomade et al., submitted). similar results occur at the site 975, whereas such palaeoceanographic event is not recorded at site 976 in the alboran sea, thus highlighting a different response to precessional forcing of the surface and deeper water masse hydrological pattern in the westernmost mediterranean. 4. discussion and conclusion the correlation among the different study sections enables to compare the response of marine (coccolithophores and planktonic foraminifera) and terrestrial proxies to climate changes through a west east transect, in different hydrological regimes of mediterranean. as a whole, the climate pattern observed at the montalbano jonico ideale section and deep-sea cores is well comparable to the synthetic greenland temperature curve (barker et al., 2011) and antarctic ice core deuterium record (jouzel et al., 2007), highlighting the interconnection between the north atlantic and the mediterranean climate during mis 19 and the global scale correlation of events and phases. references aiello g., barra d., parisi r. 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(2012) determining the natural length of the current interglacial. nat. geosci, 5, 138-141. 154 marino m. et al. ms. received: may 11, 2018 final text received: may 17, 2018 amq sr003 viganòscafidi 149-156.pub earthquake locations and their interpretation: bridging the gap between seismological data and geological phenomena. alfio viganò 1, davide scafidi 2 1 servizio geologico, provincia autonoma di trento, trento, italy. 2 dipartimento di scienze della terra, dell’ambiente e della vita, università degli studi di genova, genova, italy. corresponding author: a. viganò <alfio.vigano@provincia.tn.it> abstract: a methodological view on earthquake locations and their geological interpretation is presented. seismicity is considered a potential trigger and/or predisposing factor for different geological phenomena, like landslides or surface deformation and ruptures. assuming a physical based model of earthquake nucleation, which in turn is supported by the observation of exhumed faults, earthquake locations from seismicity datasets need to be as much as possible reliable (i.e., precise and accurate) and complete. application examples on seismicity distributions and other natural/anthropic events for the central-eastern alps (ne italy) clarify some critical points of numerical calculations and suggest a critical approach for appropriate data interpretation. keywords: earthquakes, seismic catalogues, data reliability, landslides, southern alps. available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 33 (2), 2020, 149-156 1. introduction earthquakes are the certain evidence of presentday deformation of the lithosphere and part of the energy they release, called radiated energy, reaches the earth’s surface in the form of seismic waves (e.g., kanamori & rivera, 2006). this energy quote is responsible for ground shaking and a variety of geological phenomena, such as surface deformation and rupture, rock damaging, landslide triggering, as well as impacts on people and infrastructures (e.g., keefer, 1984; boncio et al., 2010; gischig et al., 2016; ivy-ochs et al., 2017). in particular, seismic waves can both trigger, as co-seismic causes, or affect, in the sense of predisposing factors, different types of phenomena (e.g., boncio et al., 2010; gischig et al., 2016; ivy-ochs et al., 2017). for this reason, earthquake catalogues and reliable seismicity databases (e.g., chiarabba et al., 2015; viganò et al., 2015; bressan et al., 2016; guidoboni et al., 2018; rovida et al., 2019) are extensively used as reference data to study and interpret these geological phenomena and other seismotectonic features (e.g., livio et al., 2014; lu et al., 2017; avital et al., 2018). regarding seismicity datasets, earthquake locations are the crucial information. in fact, the reliable estimation of hypocentral solutions is needed to accurately estimate magnitudes (e.g., bormann, 2012), calculate focal mechanisms (e.g., viganò et al., 2008; reiter et al., 2019) and evaluate all the parameters related to hypocentral distance and seismic-ray tracing (attenuation and tomography; e.g., morasca et al., 2010; viganò et al., 2013). this is valid not only for instrumental but also historical catalogues, which permit to significantly extend the temporal range under consideration (guidoboni et al., 2018; rovida et al., 2019). for this reason, end-users should be completely aware of limits and strengths of earthquake catalogues, paying attention to the assumptions given during their creation and the constraints often made explicit by the authors themselves (see discussion in wells & coppersmith, 1994). here we present a methodological discussion on earthquake locations from seismicity catalogues and their common use for geological interpretation. we propose specific points, as a sort of minimum baggage of knowledge for non-seismologists, and we discuss some commonly accepted approaches and procedures to highlight their possible critical points. an introductory conceptual description of the earthquake source, together with some application examples about the trentino region (ne italy) are also presented. 2. earthquake physics earthquake nucleation directly deals with rock mechanics and shear/tensile failure (e.g., scholz, 2002; vavry�uk, 2011). dynamic instabilities (i.e., related to non-stable conditions in a state where acting forces are known) generate earthquakes both in the brittle (i.e., upper lithosphere) and ductile fields, because shocks are the result not only of brittle failure but also of plastic instabilities or catastrophic phase changes (ranalli, 1995). for example, self-localizing thermal runaway has been proposed to justify intermediate-depth earthquakes (john et al., 2009). this points to the fact that «the critical stress (yield strength) and the mode of failure are functions of intrinsic and extrinsic rheological parameters» (ranalli, 1995, p. 90), where rheology means deformation and flow of matter. intrinsic parameters are https://doi.org/10.26382/amq.2020.06 150 viganò a., scafidi d. related to the property of the body (i.e., rock) and thus called material parameters, such as rigidity, compressibility, viscosity. on the contrary, extrinsic parameters are temperature, pressure and time. material parameters change at varying extrinsic conditions. seismicity is strongly dependent on the thermorheological behaviour of rocks and is critically conditioned by extrinsic rheological parameters. for this reason, a great effort is made to estimate the temperature distribution along depth within the lithosphere (e.g., viganò et al., 2012). this means that thermo-rheological boundaries, intended as delimiting volumes of different intrinsic and/or extrinsic parameters, are important drivers for deformation and earthquake nucleation. a “fault” is not, or at least not only, simply a sliding plane with dislocated blocks (basic model in figure 1), but the rock volume where acting forces govern the existence of dynamic instabilities as a function of rheological parameters, which in turn could significantly vary in space and time. within this conceptual framework, seismicity can only partially fill planar surfaces in depth, being mostly located depending on crustal heterogeneities due to different crack density distributions (bressan et al., 2016). crustal heterogeneities can be accordingly interpreted as due to lithological variations and different levels of fracturing and/or presence of fluids (viganò et al., 2013). all the above considerations have feedback in the observation of exhumed fault. in fact, fault patches and splay faults (i.e., branch of faults) spread displacement over large volumes (advanced model in figure 1) (e.g., scholz, 2002; sibson, 2003). exhumed faults show very complex structures and are composed of different types of rocks (cataclasites, pseudotachylytes; sibson & toy, 2006; viganò et al., 2011), which are the result of the mechanical and fluid flow properties of the fault zone (smith et al., 2013) (real fault in figure 1). 3. earthquake location the first goal of seismology is to locate the earthquake, that is calculate where and when the initial seismic rupture occurs within the rock volume (focus or hypocentre). considering the existence, uniqueness and stability of solutions, this inverse problem is ill-posed (hadamard, 1923). as usually happens in geophysics (boaga, 2016), accepted its existence (i.e., earthquake has occurred), the solution is unstable and above all not unique. viganò et al. (2015) showed that earthquake locations from different regional bulletins can differ significantly (several kilometres between epicentres) and therefore robust and detailed relocations are needed to constrain seismotectonic interpretations. this effect is the result of several causes. at first, station coverage, because recording stations must be in sufficient number and homogeneously distributed around the epicentral area. in seismological terms, it translates to a minimum number of available phase readings (for pand swaves) and to a minimum gap value (largest azimuthal separation in degrees between nearby stations as seen from the epicentre; e.g., gap <180°). secondly, crustal (or earth) models, because different assumptions on p and s-wave velocities bring to relevant discrepancies between theoretical and observed phase arrivals times. the critical effect of an appropriate crustal velocity model in areas affected by strong lateral heterogeneities of seismic velocities has been presented by viganò et al. (2015) for the trentino region. thirdly, calculation codes. among all, hypoellipse (lahr, 1999) and nonlinloc (lomax et al., 2000) are used worldwide and should be fig. 1 fault models with different degree of conceptual complexity. in the basic model, the fault is a planar surface where stresses acting on the fault plane (�, normal stress; �, shear stress) and pore fluid pressures inside the fault (�p) are responsible for the seismic rupture. a more advanced model considers contiguous rupture patches, together with lateral splay faults and cataclastic bands (scholz, 2002). in the real case (canalone porta fault in carbonates; viganò et al., 2011), a complex structure (slip zone, fault core, damage zone; sibson, 2003) and different types of rocks can be observed (cataclasites and pseudotachylytes). 151 earthquake locations and their geological interpretation mentioned because of the different mathematical approaches and consequent results (see discussion in viganò et al., 2015). earthquake focal solutions are usually listed and grouped into seismic bulletins or earthquake catalogues. the computed hypocentral parameters include firstly the origin time, expressed as hour, minutes, seconds, and possibly hundredths of seconds, in utc/gmt time (coordinated universal time/greenwich mean time). the focus is univocally located by latitude, longitude and depth, the last implicitly given not considering topography (positive downward, starting from 0 m a.s.l.). magnitude, with explicit magnitude type (e.g., local magnitude ml, duration magnitude md, moment magnitude mw, etc.), completes the initial set of parameters. however, parameters describing the solution quality are also necessary. they are often expressed as spatial maximum errors in kilometres (horizontal and vertical errors, erh and erz) and temporal uncertainties in seconds (root mean square travel-time residual, rms) (bormann, 2012). additional parameters could be the number of phases used, or total covariance if probabilistic methods are applied (lomax et al., 2000). particular attention should be payed when historical catalogues are examined (guidoboni et al., 2018; rovida et al., 2019). since numerical models cannot be obviously applied in this case, besides origin time and epicentral coordinates the most robust information is intensity (epicentral and/or maximum) instead of magnitude. magnitude is usually inferred from intensity using empirifig. 2 examples of seismicity distribution, with location errors (red bars): hypocentres with small errors and not aligned (cross-section ab), hypocentres with small errors and aligned (cross-section c-d), hypocentres with larger errors (cross-section e-f). tn, trento. cal formulae and expressed as equivalent magnitude based on macroseismic observations (me; guidoboni et al., 2019). 4. application examples in this section, some case studies about seismological data interpretation are presented. all of them concern the central-eastern alps (ne italy; map in figure 2). as highlighted before, the interpretation of seismicity distribution needs a careful evaluation of location quality and errors. figure 2 shows three cross-sections where three groups of hypocentres (data from viganò et al., 2015) lead to different geological explanations, based on the variable level of data accuracy. in the first case, location errors are limited to a few kilometres and computed solutions at depth are very well constrained (cross section a–b of figure 2). despite this, hypocentres do not indicate clear alignments, suggesting the occurrence of a widespread deformation within a crustal body. as already discussed by viganò et al. (2015), within this volume important earthquakes occur (e.g., 29 oct 2011, ml 4.4), which can be interpreted as due to local stress accumulation and the presence of two intersecting regional fault systems, the giudicarie fold-andthrust belt and the schio-vicenza high-angle faults. in the second case, earthquake foci are vertically aligned along the veneto alpine front, in optimal agreement with the montagna nuova strike-slip fault (cross section c–d of figure 2). location accuracy is the same of the first case study. both vertical alignment and relatively small errors thus allow a complete seismological/geological interpretation. in the third case, larger horizontal and vertical errors pose a limit in the geological interpretation (cross section e–f of figure 2). in fact, it is not possible to undoubtedly distinguish between a volume-clustered seismicity and earthquakes filling a plane. figure 3 shows the effect of different computational methods in quarry shot locations, but the following considerations can be extended also to seismicity. using 1d simplified velocity models and the hypoellipse code (lahr, 1999) wrong locations at depth (i.e., imprecise) are achieved, with also unreliable minimal location errors (i.e., falsely accurate). in fact, computed errors do not permit to include the true shot locations (see numerical values in table 1). in contrast, 3-d advanced velocity models and nonlinloc probabilistic solutions (lomax et al., 2000) are able to correctly locate the events and, despite the larger computed errors (given by the nonoptimal station coverage density), to obtain highly reliable solutions. in fact, unlike tectonic earthquakes, in this case location reliability can be directly evaluated considering the true shot locations. this application example shows that, firstly, location approaches must be fully expressed by authors in catalogues and fully understood by end-users to correctly use the given solutions. secondly, smaller location errors do not necessarily mean better quality solutions. however, it should keep in mind 152 fig. 3 map and cross-section of quarry shot locations (the area is about 10 kilometres ne of the city of trento; cf. figure 2), with solutions obtained using 1d (method 1, black dots; hypoellipse code; lahr, 1999) and 3d velocity models (method 2, red stars; nonlinloc code; lomax et al., 2000). location errors are also shown (black bars) (modified from viganò et al., 2015). viganò a., scafidi d. that also advanced location methods (e.g., nonlinloc) can unreliably locate earthquakes, if not well constrained due to all the considerations given above (e.g., station coverage, velocity model). similar considerations can be done for the location of another type of geological phenomena at the earth’s surface. the cima undici rockfall, which moved about 75,000 m3 of limestones (scafidi et al., 2018), can be properly located only if the most reliable computational method for the area is applied (table 1). it should be also considered that seismic recordings related to landslides significantly differ from those of tectonic earthquakes, especially in terms of frequency content and duration. in fact, landslide spectrograms (i.e., spectra of frequencies at varying time) have a typical triangular shape, higher frequencies decay more rapidly, and the main energy content is usually found within a typical 1-5 hz range (e.g., dammeier et al., 2011; provost et al., 2018). also in the cima undici case study, a direct comparison between real and computed solutions can be performed. in contrast, since earthquake locations are necessarily given as they are and testing of the location procedure is not always possible (cf. viganò et al., 2015), a complete and thoughtful analysis on data must be performed previously they are used and interpreted. moreover, a complete check of available seismological data should be done by end-users, as a function of the geological phenomena they are dealing with. as an example, for landslides, a complete magnitude calculation (i.e., together with its computed, not broadly estimated, uncertainty value) is particularly important because crucial to apply regression curves on moved mass (manconi et al., 2016). 5. discussion and conclusions the geological interpretation of seismological data is not straightforward (e.g., barchi & mirabella, 2009). too simplistic interpretations can be given, considering 153 locations without discussing their precision and accuracy. as a typical example, the use of hypocentres (or even epicentres only) to infer the existence of a fault in depth or to demonstrate the present activity of a geologically-known tectonic structure. in general, a comprehensive analysis should firstly consider seismological data already available for the study area, in order to collect information and select the adequate database (figure 4). as a very preliminary but not obvious consideration, the number of significant digits on location parameters must be evaluated. one degree of latitude and longitude, for example in the trentino region (cf. figure 2), measure about 111 and 78 km, respectively. so, three decimal digits for latitude and longitude degree values mean about 0.1 km in both the cases. since location errors for earthquakes are typically larger than 1 km, a number of significant digits greater than 3 essentially does not make sense and is severely misleading. geological interpreters must properly consider location coordinates with errors and, consequently, plot epicentral distributions. similar considerations on significant digits should be clearly done also for all the other solutions parameters (i.e., depth, errors themselves, etc.). as mentioned before, it should be emphasized that seismic network configuration plays a crucial role in location solutions and their quality assessment. in particular, many parameters act jointly, such as the total number of stations and their epicentral distance, azimuthal gap, and the presence of at least one recording station relatively near the epicentre (e.g., bondár et al., 2004; tiira et al., 2016). then, a possibly complete identification of the geological phenomena should be done, with also the estimation of their uncertainties on, for example, mechanisms, driving factors and age (figure 4). this leads to the core phase, where earthquake locations are used and interpreted. assuming in-depth analyses on data, method and solution quality (for instrumental seismicity), any interpretation must be conceptually (i.e., within the earthquake locations and their geological interpretation tab. 1 real and computed locations for two events occurred at the earth’s surface (fornace quarry shot and cima undici rockfall). “method 1” is given by hypoellipse code (lahr, 1999) and 1-d velocity model; “method 2” is given by nonlinloc code (lomax et al., 2000) and 3-d velocity model. erh, horizontal error; erz, vertical error; rms, root mean square; ml, local magnitude (with computed uncertainty). range of theoretical applicability) and quantitatively (i.e., within value uncertainties) consequential from seismological data. in other words, we must make sure that we do not let the data say what they cannot say. finally, data reliability concerns not only about precision and accuracy, but also completeness (figure 4). as an example, if we would like to make a selection on historical seismicity for the central-eastern alps to be compared to catastrophic landslides in this region (cf. ivy-ochs et al., 2017), we must consider the most complete catalogues (cfti5med by guidoboni et al., 2018; cpti15 vers. 2 by rovida et al., 2019). if we uncritically plot epicentral coordinates from cfti5med and cpti15 we obtain two different results. in the first case, we include the most relevant historical earthquake in southern trentino (the “middle adige valley” event, 1046 ad). in the second case, we completely miss it (the earthquake is listed but not completed with epicentral coordinates, due to specific choices in event selection). in conclusions, final remarks can be summarized as follows: �� a complete and appropriate use of earthquake locations is a difficult task, because both their calculation is an ill-posed inverse problem and their geological interpretation is not straightforward. �� rheological theory on earthquake nucleation and realistic conceptual models of faults imply a careful analysis of seismicity datasets, in terms of data, method and solution quality, to assess their overall reliability. �� a comprehensive check-list for non-seismologists is able to support data interpretation, in order to better explain geological phenomena and avoid some commonly accepted critical points. 154 fig. 4 comprehensive check-list for earthquake location data analysis and interpretation. viganò a., scafidi d. lease of the catalogue of strong earthquakes in italy and in the mediterranean area. scientific data, 6:80. doi: 10.1038/s41597-019-0091-9 hadamard j. (1923) lectures on cauchy’s problem in linear partial differential equations. dover phoenix editions. dover publications, new york, pp. 22. ivy-ochs s., martin s., campedel p., hippe k., alfimov v., vockenhuber c., andreotti e., carugati g., pasqual d., rigo m., viganò a. (2017) geomorphology and age of the marocche di dro rock avalanches (trentino, italy). quaternary science reviews, 169, 188-205. john t., medvedev s., rüpke l.h., andersen t.b., podladchikov y.y., austrheim h. (2009) generation of intermediate-depth earthquakes by selflocalizing thermal runaway. nature geoscience, 2, 137-140. kanamori h., rivera l. (2006) energy partitioning during an earthquake. in: abercrombie r., mcgarr a., di toro g., kanamori h. (eds.) earthquakes: radiated energy and the physics of faulting. geophysical monograph, 170, 3-13. keefer d.k. (1984) landslides caused by earthquakes. geological society of america bulletin, 95, 406421. lahr j.c. 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(2017) interpreting soft sediment deformation and mass transport deposits as seismites in the dead sea depocenter. journal of geophysical research, solid earth, 122, 8305-8325. manconi a., picozzi m., coviello v., de santis f., elia l. (2016) real-time detection, location, and characterization of rockslides using broadband regional seismic networks. geophysical research letters, 43, 6960-6967. morasca p., massa m., laprocina e., mayeda k., phillips s., malagnini l., spallarossa d., costa g., augliera p. 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(2012) geothermal and rheological regime in the po plain sector of adria (northern italy). italian journal of geosciences, 131, 228240. viganò a., scafidi d., martin s., spallarossa d. (2013) structure and properties of the adriatic crust in the central-eastern southern alps (italy) from local earthquake tomography. terra nova, 25, 504-512. viganò a., scafidi d., ranalli g., martin s., della vedova b., spallarossa d. (2015) earthquake relocations, crustal rheology, and active deformation in the central-eastern alps (n italy). tectonophysics, 661, 81-98. wells d.l., coppersmith k.j. (1994) new empirical relationships among magnitude, rupture length, rupture width, rupture area, and surface displacement. bulletin of the seismological society of america, 84, 974-1002. 156 viganò a., scafidi d. ms. received: june 29, 2020 revised: august 10, 2020 accepted: august 10, 2020 available online: november 30, 2020 available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 23 26 late quaternary geology and morphoevolution of the volturno coastal plain, southern italy giuseppe corrado 1 , sabrina amodio 1 , pietro p.c. aucelli 1 , pietro incontri 1 , gerardo pappone 1 , marcello schiattarella 2 1 dipartimento di scienze e tecnologie, parthenope university, naploli, italy 2 dipartimento delle culture europee e del mediterraneo (dicem), basilicata university, matera, italy corresponding author: g. corrado <giuseppe.corrado@uniparthenope.it> abstract: the volturno alluvial-coastal plain is a relevant feature of the tyrrhenian side of southern italy. its plan-view squared shape is due to pliocene-quaternary block-faulting of the western flank of the chain. the quaternary infill of the volturno plain has been here studied by means of well data. an asymmetrical shape of its ancient morphology – with a steeper slope toward the north-west border – and the lack of coincidence between the present course of the volturno river and the main buried bedrock incision are significant achievements of this study. landforms analysis completed the frame of the recent evolution of the plain. keywords: well log correlation, late quaternary evolution, volturno coastal plain, southern italy 1. introduction the alluvial-coastal plain of the volturno river is a relevant feature of the tyrrhenian side of the italian south-apennine chain. in a planimetric view, it has a roughly quadrangular shape, due to pliocenequaternary block-faulting of the western flank of the orogen after the tertiary extension of the back-arc basin. the plain is in fact bordered by the structural highs of mt. massico and caserta mts to the north-west and north-east, respectively, and by the ischia island phlegraean fields volcanic alignment to the south-east. this area has already been studied and the state-of-art literature is proposed in santangelo et al. (2017). several authors investigated the infill stratigraphy of such a structural depression by means of borehole analysis (romano et al., 1994; barra et al., 1996; santangelo et al., 2010; amorosi et al., 2012; sacchi et al., 2014). the absence of pliocene marine deposits in the deepest boreholes suggests that the plain was above sea level during late tertiary times. anyway, during the quaternary, the tectonic subsidence favoured the accommodation of more than 3000 m of marine, transitional, and alluvial sediments (santangelo et al., 2017, and references therein). during the first part of the late pleistocene, the filling of plain was helped by the onset of volcanic activity from different sources. at about 39 ka b.p. the huge eruption of campanian ignimbrite (ci) occurred (rolandi et al., 2003, and references therein) and uniformly covered the entire plain with a pyroclastic flow deposit tens of meters thick. tephra deposits interbedded with sediments provide important stratigraphic and geochronological markers. in the second part of the late pleistocene, the whole plain emerged due to the subsidence rate reduction and the contemporary last glacial regression. during the holocene, the plain underwent diffuse flooding in concomitance with the peak of the post-glacial transgression. the subsequent decrease of the sea level rise favoured coastal progradation and development of lagoon and swamp systems several kilometres inland from the present coastline (barra et al., 1996; amorosi et al., 2012). in this work, we present the results of an extensive and detailed stratigraphic analysis of the late pleistocene holocene infill of the volturno plain based on almost 700 well logs generally not exceeding 30 m of depth from the ground level. further, the geomorphological analysis of the quaternary elements of the landscape such as coastal features and foothill-plain connecting landforms has completed the frame of the recent evolution of the plain. the aim of this study is to define a detailed palaeoenvironmental and stratigraphic reconstruction after the ci eruption and the role of tectonic and eustatic forcing in the evolution of the coastal plain. 2. material and methods a subsurface lithostratigraphic dataset based on 680 wells drilled in the plain was integrated by geological cartography and field survey. detailed sedimentological analysis and facies interpretation were acquired from literature (e.g. romano et al., 1994; amorosi et al., 2012) and other unpublished data. all these data have constituted the core for the reconstruction of a quaternary stratigraphic succession. such a task has needed an effort to homogenize data from different sources by using log charts and their precise positioning in a gis. subsurface data have been used to realize geological crosssections and a map of roof of the ci by gis interpolation techniques. age determination for stratigraphic correlations is based on constraints of volcanic and marine deposits from literature (see references in results). https://doi.org/10.26382/aiqua.2018.aiquaconference 3. results the stratigraphic architecture of the late quaternary volturno plain infill has been reconstructed and seven lithostratigraphic units based on homogeneous sedimentological and palaeontological criteria have been individuated (fig. 1). hereinafter, they are briefly described from the younger to the older one, including their stratigraphic contacts with the adjacent units. stratigraphic and chronological constraints enable us to propose a general chronology and to attribute age intervals for each unit. unit 1 holocene deposits (12-0 ka) represent a complex and articulated sedimentary body progressively formed from sea to the land by four sub-units characterised by lateral transitional contacts: prodelta (u1a, clays and silts with euryhaline fossils), beach-dune ridge (u1b, well sorted sands with marine shells), lagoonal-swamp (u1c, clays with organic matter and freshwater gastropods) and alluvial (u1d, pedogenised clays and silts with sand lens) deposits. the u1 bottom is normally the u4 (ci), which also represents its lateral contact towards north and east. the pleistocene alluvial (u3) and pyroclastic (u2) deposits, represent a very discontinuous substrate for this unit. by integrating subsurface and literature (romano et al., 1994; barra et al., 1996; amorosi et al., 2012, sacchi et al., 2014) data, the u1 can be considered 24 fig. 1a) simplified geological map of the volturno plain area. legend: br: pre-quaternary bedrock; u4: campanian ignimbrite (late pleistocene); u2: depositional unit composed of both volcaniclastic sediments and pyroclastic units (giugliano ignimbrite and neapolitan yellow tuff, late pleistocene); u1d: alluvial deposits (holocene); u1c: back-dune ridge deposits (holocene); u1b: beach-dune ridge deposits (holocene); dt: slope deposits (late pleistocene – holocene). b) contour map of the campanian ignimbrite roof and inferred course of the palaeo-volturno river. c) geological cross-sections obtained from well logs (30x vertical exaggeration). corrado g. et al. 25 as holocene transgressive-regressive depositional complex. unit 2 pyroclastic flow and fall deposits and volcanoclastic sediments (23-12 ka b.p.) represented by the giugliano ignimbrite (gi; age 23-18 ka b.p., after rolandi et al., 2003) below and the neapolitan yellow tuff (nyt, ~12 ka b.p. in age, rolandi et al., 2003) above, deposited in subaerial conditions, and by their reworked deposits. the u2, bounded at the bottom by a palaeosol, mostly occurs in the southern sector of the volturno plain above the ci (u4). unit 3 late pleistocene alluvial plain deposits (29-39? ka b.p.) occur as channelled fills (gravels, sands passing upward to silts with peat intercalations) of fluvial palaeochannels incised in the u4. it is highly discontinuous and covered by u1 and u2 (radiometric age 37 ka b.p., after amorosi et al., 2012). unit 4 campanian ignimbrite (ci, 39 ka b.p.). pyroclastic deposits, laterally continuous, attributed to a highly explosive eruption of the phlegraean fields (rolandi et al., 2003 and references therein), covering the entire ancient plain with an articulate palaeotopography (fig. 1b). ci erosional roof shows progressively higher depths (about -35 m b.s.l.) towards the centre of the plain. unit 5 coastal-marine and transitional deposits with alluvial episodes (~?50-39 ka b.p.). yellowish and grey sands with molluscan shells, and clays with local peat lens represent the main lithology of this unit, which is the substrate of the ci and u3 at depth more than -35 m b.s.l. in central plain and above sea level in proximity of border relief. unit 6 pre-ci volcaniclastic deposits (~50-105 ka b.p.) erupted by roccamonfina and phlegraean fields and locally separated by thin palaeosols are included in this unit, which appears more discontinuous in the northern than in central and southern sectors of the plain. the u6 rests upon u7 by an erosional contact and is covered by the u4 and u5. its age is based on radiometric (~50-105 ka b.p.) and palaeoenvironmental constraints (romano et al., 1994; santangelo et al., 2010). unit 7 coastal-marine and transitional deposits (~105130 ka b.p.) are composed of fossiliferous clays and silts interbedded with yellow sands or fine gravels (u/ th dating ~126 ka b.p., after romano et al., 1994; >105 ka b.p., after santangelo et al. 2010). this unit is continuous and the deepest one, placed between 20 m a.s.l. in proximity of border relief and between 20 and -90 m b.s.l., on the left and right sides of the volturno river, respectively. these deposits cover lava bodies in the southern sector of the plain ascribed to the buried parete volcano. stratigraphic relationships of the above described units, partly represented in the geological cross-sections of figure 1c, suggest a complex late quaternary sedimentary evolution starting from the deposition of the ci, which represents the substratum of late pleistoceneholocene sediments. the subsurface channelized buried landforms in the ci substratum testifies the palaeovolturno river incision as a consequence of mis 2 sea level low stand. the facies analysis of holocene units indicates that the volturno river channel shifted from se to the present-day position (fig. 1b and fig. 1c, cross -section a). the deposition of the holocene unit 1 (coastal-lagoonal-swamp-alluvial sedimentary body) testifies the rapid marine transgression recorded by the progressive onlap of the beach-dune ridge sands on continental deposits. the maximum landward shift of transgressive sands can be estimated of about 3-4 km on average respect to the present-day position, so as the palaeo-position of the back-barrier environments is further inland. 4. discussion and conclusions the significant achievements of this research are: a) a better knowledge of distribution and evolution of the coastal-marine to continental palaeoenvironments of the volturno plain during the late quaternary; b) the reconstruction of base and roof of the campanian ignimbrite that – integrated by geomorphological analysis of the quaternary elements of the landscape has allowed upgrading the 3d shape of the volturno plain palaeomorphology before the deposition of late upper pleistocene holocene sediments. in fact, it is now possible to infer an asymmetrical shape of the ancient morphology of the plain with a steeper slope toward the north-west border (i.e. mt. massico morphostructural high) and the lack of coincidence between the present course of the volturno river and the main buried bedrock incision. based on these data, it is possible to affirm that the late quaternary evolution of the volturno plain has been mainly controlled by eustatic changes of sea level during which intense volcanic activity occurred. the rapid sea level rise after the last glacial maximum is testified by a backstepping depositional architecture of the holocene delta-coastal and lagoonal-swamp system directly on late pleistocene incised palaeo-volturno plain. the maximum ingression of the shoreline was about 3-4 km inland. starting from about 5 ka b.p., in response of the decreasing rate of sea level rise, a prominent coastal and delta system progradation and alluvial aggradation is documented from well and field data. however, taking into account also the subsidence data (aucelli et al., 2016; matano et al., 2018), late quaternary tectonics should be considered active to produce the asymmetry the ci roof as well as the lateral migration of the volturno river during this time interval. such a trend seems to continue in more recent times, as testified by the location of a thick alluvial succession (fig. 1c, cross-section a) south of the present-day main channel. references amorosi a., pacifico a., rossi v., ruberti d. (2012) late quaternary incision and deposition in an active volcanic setting: the volturno valley fill, southern italy. sedimentary geology, 242, 307-320. aucelli p.p.c., di paola g., incontri p., rizzo a., vilardo g., benassai g., buonocore b., pappone g. (2016) coastal inundation risk assessment due to subsidence and sea level rise in a mediterranean late quaternary evolution of the volturno coastal plain alluvial plain (volturno coastal plain, southern italy). estuarine coastal shelf science, 198, 597609. barra d., romano p., santo a., campaiola l., roca v., tuniz c. (1996) the versilian transgression in the volturno river plain (campania, southern italy): palaeoenvironmental history and chronological data. il quaternario, 9 (2), 445-458. matano f., sacchi m., vigliotti m., ruberti d. (2018) subsidence trends of volturno river coastal plain (northern campania, southern italy) inferred by sar interferometry data. geosciences, 8. doi: 10.3390/geosciences8010008. rolandi g., bellucci f., heizler m.t., belkin h.e., de vivo b. (2003) tectonic controls on the genesis of ignimbrites from the campania volcanic zone, southern italy. mineralogy and petrology, 79, 3-31. romano p., santo a., voltaggio m. (1994) l’evoluzione geomorfologica della pianura del f. volturno (campania) durante il tardo quaternario (pleistocene medio-superiore olocene). il quaternario, 7 (1), 41-56. sacchi, m., molisso, f., pacifico, a., vigliotti, m., sabbarese, c., ruberti, d. (2014) late-holocene to recent evolution of lake patria, south italy: an example of a coastal lagoon within a mediterranean delta system. globary and planetary change, 117, 9-27. santangelo, n., ciampo, g., di donato, v., esposito, p., petrosino, p., romano, p., russo ermolli, e., santo, a., toscano, f., villa, i. (2010) late quaternary buried lagoons in the northern campania plain (southern italy): evolution of a coastal system under the influence of volcano-tectonics and eustatism. bollettino della società geologica italiana, 129 (1), 156-175. santangelo n., romano p., ascione a., russo ermolli e. (2017) quaternary evolution of southern apennines coastal plains: a review. geologica carpathica, 68 (1), 43-56. 26 corrado g. et al. ms. received: may 15, 2018 final text received: may 21, 2018 available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 11 12 mediterranean sea: many models and few new observational data for the coast, only using the computer will be difficult to improve the projections of the future sea level fabrizio antonioli enea, casaccia, roma, italy corresponding author: f. antonioli <fabrizio.antonioli@enea.it> abstract: over the last few years many papers on sea level change was published without provide observational data in the field, only using large data base and computer, this involves frequent errors in the field data interpretation. keywords: sea level change, model, observational data 1. introduction over the last few years, many papers on sea level change, projection for the future, observational data reviews, isostatic models based on ice melting, have been published, but statistically the reviews or modelling papers are much more frequent than new observational data papers. on the contrary, the mediterranean coasts still reserve many discoveries (geoswim project, furlani et al., 2017a, b) and, less and less are the young researchers that observe in the field, study, date, using geomorphological, archaeological, biological markers strictly related with sea level. 2. data pedoja et al. (2011; 2014), published a review for the last interglacial highstand all over the world, taking in account 890 and 926 sites. but to treat them with analytical and statistical uniformity, authors apply some forcing, for example establish zero-meter as the eustatic sea level during the mis 5.5. the result is written in the title of the first paper: “relative sea-level fall since the last interglacial stage: are coasts uplifting worldwide?” using the paper by antonioli et al. (2006), authors wrote, for example: “… two highstands during mis 5e have been deduced, either from morphological analysis or deposits, in tunisia (jedoui et al., 2003), italy (antonioli et al., 2006)" while in antonioli et al. (2006), authors reported a tidal notch and a smoothed notch due to isostasy contribution, therefore due to only one highstand. evelpidu et al. (2012), returns to measure the same fishtanks (punta della vipera, lambeck et al., 2004) measured by pirazzoli (1976), again without the archaeologists (ignoring classical authors, included plinius the elder, columella and varro) measuring the wrong marker, a sea level of 2 ka bp at -50 cm, datum is confirmed by the predictive model ice 5g/selen. using the same model three years before (antonioli et al., 2009) the same author on the same site, predicted a sea level of -128 cm. this obviously creates a lot of confusion. roy and peltier 2018, published a new model for the mediterranean sea (ice 7g) but, as example, comparing the observational data for northern sardinia (grotta verde, -11 metres at 7300 yrs bp, by palombo et al., 2017) with prediction, the "stable" northern sardinia seems to be in subsidence. in addition, also here authors (from canada) established the sea level during roman age at -48 cm, without ever having seen a fishtank in the field. 3. remarks a model before being validated must be tested on the field in the stable areas, and possibly changed if in disagreement with observational data (see fig 1). references antonioli, f., ferranti, l., kershaw, s. (2006) a glacial isostatic adjustment origin for double mis 5.5 and holocene marine notches in the coastline of italy. quaternary international quaternary sea-level changes: contributions from the 32nd igc, 145146, 19-29. antonioli, f., ferranti, l., fontana, a., amorosi, a., bondesan, a., braitenberg, c., dutton, a., fontolan, g., furlani, s., lambeck, k., mastronuzzi, g., monaco, c., spada, g., stocchi, p. (2009) holocene relative sea-level changes and vertical movements along the italian coastline. quat. int., 221, 37 -51. evelpidou, n., pirazzoli, p., vassilopoulos, a., spada, g., ruggieri, g., tomasin, a., (2012) late holocene sea level reconstructions based on observations of roman fish tanks, tyrrhenian coast of italy. geoarchaeology 27 (3), 259-277. furlani s., antonioli f., gambin t., gauci r., ninfo a., zavagno e., micallef a., cucchi f. (2017a) marine https://doi.org/10.26382/aiqua.2018.aiquaconference notches on the maltese islands (central mediterranean sea). quaternary international, 439, 158168. furlani s., antonioli f., cavallaro d., chirco p., caldareri f., foresta martin f., gasparo morticelli m., monaco c., sulli a., quarta g., biolchi s., sannino g., de vita s., calcagnile l., agate m. (2017b) -coastal landforms and late quaternary relative sea level changes at ustica (sicily, southern italy). geomorphology, 299, 94-106. lambeck k., anzidei m., antonioli f., benini a, esposito e. (2014) -sea level in roman time in the central mediterranean and implications for modern sea level rise. earth planet. sci. lett., 224, 563-575. palombo m.r, antonioli f., lo presti v., mannino m., melis r., orru p., stocchi p., talamo s., quarta g., calcagnile l., deiana g., altamura s. (2017) the late pleistocene to holocene palaeogeographic evolution of the porto conte area: clues for a better understanding of human colonization of sardinia and faunal dynamics during the last 30 ka. quaternary international, 439, 117-140. doi: 10.1016/j.quaint.2016.06.014 pedoja, k., husson, l., regard, v., cobbold, p.r., ostanciaux, e., johnson, m.e., weill, p. (2011) relative sea-level fall since the last interglacial stage: are coasts uplifting worldwide?. earth sci. rev. 108, 1-15. pedoja, k., husson, l., johnson, m.e., melnick, d.,witt, c., pochat, s., nexer, m., delcaillau,b., pinegina, t., poprawski, y., authemayou, c., elliot,m., regard, v., garestier, f. (2014) coastal staircase sequences reflecting sea-level oscillations and tectonic uplift during the quaternary and neogene. earth sci. rev. 132, 13-38. pirazzoli, p. (1976) -sea level variations in the northwest mediterranean during roman times. science 194, 519-521. roy k., peltier w.r. (2018) relative sea level in the western mediterranean basin: a regional test of the ice-7g_na (vm7) model and a constraint on late holocene antarctic deglaciation quaternary science reviews, 183, 76-87. 12 antonioli f. fig 1 kurt lambeck seminar at ingv on may 2018. ms. received: may 15, 2018 final text received: may 22, 2018 available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 34 (1), 2021, 5-16 an overview of the middle pleistocene in the north mediterranean region. flavia strani 1,2 , raffaele sardella 1 , beniamino mecozzi 1 1 dipartimento di scienze della terra, paleofactory, sapienza università di roma, italy. 2 istituto italiano di paleontologia umana, roma, italy corresponding author: f. strani <flavia.strani@uniroma1.it> abstract: the middle pleistocene was a crucial stage for the evolution of european mammals, a time when the majority of the modern taxa appeared in the continent for the first time. it is also in this interval that periodicity and intensity of glacial-interglacial cycles changed, an event that strongly impacted on mediterranean marine and terrestrial ecosystems, and on vertebrate communities. this area can thus be considered an important laboratory to investigate how major climatic events influenced mammals’ communities (among which also hominin populations) and the habitats they occupied. the state of art of the middle pleistocene palaeontological, archaeological and palaeoanthropological record of north mediterranean region, and of the italian peninsula in particular, is here discussed. keywords: chibanian, european ecosystems, early-middle pleistocene transition, biochronology, mammals, human evolution. 1. introduction the definition of the early-middle pleistocene boundary triggered an intense debate among quaternary geologists, stratigraphers, and palaeontologists (cita et al., 2006; gibbard & head, 2010; head & gibbard, 2015). a large consensus was reached during the xii inqua congress, and the beginning of the middle pleistocene was placed at the matuyama/bruhnes palaeomagnetic reversal (~0.78 ma), within the marine isotope stage (mis) 19. no doubts instead for the end of the middle pleistocene, placed at 129 ka, which corresponds to the beginning of the last interglacial (mis 5), that therefore marks the start of the late pleistocene. after a long-lasting debate, the middle pleistocene has been referred to the chronostratigraphic chibanian stage, from a sequence located in chiba prefecture (japan) and ratified by iugs in january 2020 (suganuma et al., 2021). the middle pleistocene subepoch represents a crucial phase for the earth system as it witnessed the change in the frequency of glacialinterglacial cycles from 41 kyr to 100 kyr occurred during the 1.20.4 ma (with some authors placing its onset as far back as 1.4 ma, see: head & gibbard, 2015) interval, an event known as the middle pleistocene revolution (mpr) or early-middle pleistocene transition (empt) (clark et al., 2006; head & gibbard, 2015; maslin & brierly, 2015). the consolidation of the empt is conventionally placed around the mis 12 11 passage during the mid-brunhes event (mbe) after which an increase of the amplitude of the glacial and interglacial periods is recorded (head & gibbard, 2015). during the last two decades, a large number of studies on the european middle pleistocene provided novel knowledge on palaeoenvironments, palaeoclimates and vertebrate communities, and a valuable amount of data on the mediterranean europe, and italian peninsula in particular. many issues are still unclear among the specialists, mainly due to the fragmentary framework of the discoveries. the state of art of the palaeontological, palaeoanthropological and archaeological research is thus crucial for a comprehensive understanding of european palaeoenvironmental dynamics and mammal palaeocommunities. here, we briefly discuss these aspects, offering an overview of key aspects on the study of the middle pleistocene in the mediterranean region. 2. old issues and new perspectives during the last two decades, the knowledge on middle pleistocene ecosystems has been enriched by a number of papers (e.g., rivals, 2012; strani et al., 2018; bellucci et al., 2021). of special interest are those focused on new methods, which allowed to investigate different aspects of archaeological and palaeontological deposits, or to correlate different palaeoenvironmental proxies and palaeoclimate records (rivals et al., 2009; strani et al., 2018). also, the application of isotopic analysis on sediments, speleothems and vertebrate remains has become more diffused (kuitems et al., 2015; pushkina et al., 2020). the results of these researches potentially provide crucial information on palaeoenvironments and climate. https://doi.org/10.26382/amq.2021.13 6 strani f. et al. another aspect which needs to be stressed concerns the radiometric method used for reliable chronological constrains of quaternary sedimentary successions. during the 1960s, these methodologies were already available for the specialists, but in the last decade the technological progress allows to refine the obtained chronological data with both radiometric (radiocarbon, ar-ar, u-series) and electron spin resonance (esr) dating. a number of studies focused on the definition of more accurate chronological framework have been published during the last decade, providing a new age for some key pleistocene deposits. an example is the new age of the fontana ranuccio deposit dated at 408 ±10 ka (pereira et al., 2018), whereas historically its age was of 458 ±6 ka (biddittu et al., 1979; segre & ascenzi, 1984) shifting the age of the deposits from full glacial conditions of mis12 to interglacial mis11. however, despite the increased use of the radiometric and esr methods, still nowadays only a limited number of european deposits possess reliable chronological constrains. this explains why the reconstruction of the human and vertebrate evolution and of quaternary ecosystems dynamics is based only on few localities (e.g., gliozzi et al., 1997). in addition to this, it is necessary to consider that many works were historically published on local journals, often in the authors native language (italian, spanish, french, etc..), or just discussed in master/doctoral theses. these researches are hardly available for international scientists, being a strong impediment in the understanding of palaeocommunity changes across the middle pleistocene. in summary, despite the recent improvement, palaeontological, palaeoanthropological and archaeological data for some middle pleistocene european localities, especially those of north-central mediterranean region, are either quite scarce or not well disseminated, and this represents an important limiting factor for the reconstruction of the mammal fauna evolution and their response to the environmental changes that occurred during this pivotal phase of the quaternary. a review of the state of art of middle pleistocene research and new data on historical key sites can therefore offer crucial data for the understanding of mediterranean palaeoenvironmental dynamics and mammal palaeocommunities. 3. the middle pleistocene terrestrial ecosystems in north-central mediterranean region 3.1. paleobotanical framework in northern mediterranean europe, a drop in temperature and a change in the dominant cyclicity strongly influenced the terrestrial ecosystems during the earlymiddle pleistocene transition until the end of pleistocene (bertini, 2010; russo ermolli et al., 2010a; kahlke et al., 2011; combourieu-nebout et al., 2015; head & gibbard, 2015; strani, 2020). the european vegetational landscapes generally changed following global climate patterns. as bertini (2010) pointed out, “a close correspondence between the climate fluctuations recorded by marine oxygen isotope records and long pollen records during the pleistocene indicates that there were also considerable regional differences in the vegetation structure, composition and responses to climate, depending on geographic and historical factors”. in the mediterranean area, and in the italian peninsula in particular, such a condition is evident. alternation of artemisia steppe and thermophilous forest marks the overall glacial-interglacial vegetation change. “taxodiaceae”, cathaya (plus p. haploxylon type), tsuga, cedrus, carya, pterocarya, along with other taxa, progressively disappeared throughout the pleistocene, with the last subtropical elements being extirpated during the middle pleistocene due to the increased severity of the glacial periods (bertini, 2010; manzi et al., 2011; combourieunebout et al., 2015). the effect of climatic changes can be clearly observed in central and southern italy, especially during glacial stages where the expansion of steppe and grasslands occurred (manzi et al., 2011). even if the record is quite fragmentary, a marked shift can be detected between 0.7-0.6 ma, probably due to the extreme climate conditions recognized during the mis 16. the following interglacial stage (mis 15) included modern taxa, as carpinus and ulmus, testifying therefore a clear vegetation turnover (manzi et al., 2011). another vegetational shifts occurred in correspondence of mis 12, with major effects in southern italy (russo ermolli et al., 2010b). the latter coincides with the mid-brunhes event (mbe), with marks the mis 12 11 transition, after which an increase of the amplitude of the glacial and interglacial periods is recorded. generally speaking, deciduous quercus or fagus dominated forests, and typical mediterranean taxa (e.g. quercus ilex) become the most common vegetation during middle pleistocene interglacials, whereas conifers, steppe and grasslands expanded during glacial periods (russo ermolli et al., 2010a,b; bertini, 2010; manzi et al., 2011; magri & palombo, 2013; combourieu-nebout et al., 2015). 3.2. mammal faunas and biochronology the mammal biochronological scale is based on the evolutionary degree of the faunal elements of the assemblages and on their dispersal, and therefore their first and last occurrences mark pivotal bioevents (gliozzi et al., 1997). the villafranchian/galerian transition (corresponding to the 1.2-0.9 ma interval) can be considered one of the most controversial issues in the european biochronological framework. the marked faunal turnover recorded within the jaramillo subchron occurred following the shift to glacial-interglacial cycles dominated by a 100 kyr frequency. the use of the term epivillafranchian, suggested by kahlke (2009) for the villafranchian/galerian transitional faunas, has been formally defined (bellucci et al., 2015). taking into account the data recorded from the european localities, during the epivillafranchian biochron, the first occurrence of praemegaceros verticornis, bison menneri, megaloceros savini, cervus elaphus and sus scrofa are recognized (bellucci et al., 2015). in the revised framework proposed by bellucci et al. (2015), the crocuta crocuta bioevent (sardella & palombo, 2007; sardella & petrucci, 2012) marks the beginning of galerian, and therefore the end of epivillafranchian. one of the most important sites for the study of the middle pleistocene is the area of ponte galeria (rome, central italy), where sedimentary sequences exposed in quarries have been studied by geologists and palaeontologists for decades. these deposits provided a rich fossil vertebrate collection, which allows the development of an important part of quaternary biochronology. the terms galerian and aurelian (mammal ages) themselves have their origin from ponte galeria sites and from many palaeontological sites located along the aurelia state highway, respectively (e.g., gliozzi et al., 1997; di stefano et al., 1998; petronio & sardella, 1999; milli et al., 2004; romano et al., 2021). after bellucci et al. (2015) revision the galerian mammal age includes three faunal units: ponte galeria, isernia and fontana ranuccio (gliozzi et al., 1997; petronio & sardella, 1999; fig. 1). since the end of the xx century a more detailed biochronological framework has been set up (milli et al., 2004; sardella, 2007; palombo et al., 2008, 2009; petronio et al., 2011; marra et al., 2014; bellucci et al., 2015; sardella et al., 2015). therefore, most of the more significative fossil mammal assemblages from which the middle pleistocene biochronology has been defined, come from the campagna romana area. for instance, at casal selce the large mammal fauna renewal of ungulates and carnivorans during the earlymiddle pleistocene transition is documented with the presence of mammuthus trogontherii, hemibos galerianus, praemegaceros verticornis and megaloceros savini (petronio & sardella, 1998; palombo & sardella, 2007; sardella & petrucci, 2012). as aforementioned, the fossil record of casal selce also documents the earliest occurrence of crocuta crocuta (c. crocuta event), that replaced the villafranchian giant hyaena pachycrocuta brevirostris (sardella & petrucci, 2012). among the bovids, important elements of the galerian faunas are bison schoetensacki, praeovibos and ovibos. as highlighted by iannucci et al. (2021), the aurochs bos primigenius spread around 0.5 ma in italy, becoming soon a common element of the galerianaurelian faunal assemblages of europe. in addition to these taxa, the rare water buffalo bubalus murrensis also occurs and spread into northern europe during temperate climatic stages (sardella, 2007 and references therein), whereas the hemibos galerianus is quite scarce (petronio & sardella, 1998; martinez-navarro & palombo, 2007). among cervids, in the early middle pleistocene european faunas praemegaceros verticornis, megaloceros savini and dama roberti are recorded (e.g., sardella et al., 2006; sardella, 2007; breda & lis 7 an overview of the middle pleistocene in the north mediterranean region fig. 1 integrated chronological scheme of the middle pleistocene and selected localities considered in this work (modified from gliozzi et al., 1997). project initiated during the 2015, whose preliminary results suggest that a possible late middle pleistocene age for the lower complex cannot be ruled out (sardella et al., 2018, 2019; mecozzi et al., 2021a). the narrownosed rhinoceros, s. hemitoechus is instead an important marker, as its earliest occurrence in europe is dated approximately at 0.5 ma (caune de l’arago, from levels chronologically referred to mis 14; moigne et al., 2006). among the equids, two villafranchian taxa persisted during the early middle pleistocene, equus altidens and equus sussenbornensis (boulbes & asperen, 2019). the modern caballoid diffused in europe approximately at 0.6 ma, but there are different interpretations of the variability of the middle pleistocene equids: as ecomorphological adaptations (equus ferus spp.) or as two distinct forms (equus mosbachensis and equus ferus) (boulbes & asperen, 2019 and reference therein). the first true horse remains have been generally attributed to e. mosbachensis, a taxon that appears present in europe from the early to the late middle pleistocene, until the first dispersal of equus ferus (e.g., boulbes & asperen, 2019; strani et al., 2019; mecozzi & strani, 2021; saarinen et al., 2021; strani et al., 2021). during the middle pleistocene equus hydruntinus is also recorded for the first time, but its dispersal is not a synchronous event. in spain, the earliest presence of this taxon is probably attested at about 0.6 ma, whereas in italy its dispersal is considered as chronological marker of the aurelian biochron (mis 10-9) (boulbes & asperen, 2019 and reference therein; fig. 1). in france, the earliest record of this equid is documented from late middle pleistocene localities of lunel-viel (mis 9-7) and orgnac (mis 9-8) (boulbes & asperen, 2019; brugal et al., 2021 this volume). another important event of the middle pleistocene is the earliest occurrence of the brown bear ursus arctos, historically placed within the fontana ranuccio faunal unit (fig. 1), based on findings unearthed in the homonymous local fauna of fontana ranuccio (0.4 ma, mis 11), where this species was found in association with ursus deningeri (azzaroli, 1983). the ursid record from this locality has been revised by conti et al. (2021), who cannot confirm with certainty the occurrence of u. arctos. in the fontana ranuccio locality are however recorded other modern taxa both within the large (e.g. cervus, dama, bos) and small mammal assemblage (e.g. lepus, erinaceus, eliomys) (strani et al., 2018; bona & strani, this volume). european primates and carnivoran records are quite scarce, and the majority of the mediumand largesized taxa became extinct during the middle pleistocene, like the large felid panthera gombaszoegensis (sardella, 2007). the barbary macaque, macaca sylvanus, is recorded in a few italian middle pleistocene localities (mecozzi et al., 2021c). its presence offers important data for the reconstruction of the mediterranean palaeoenvironments, and the findings associated with lithic artifacts require particular attention to the potential homo-macaca interactions during the pleistocene (strani et al., 2018; mecozzi et al., 2021c). in addition to iconic predators like crocuta crocuta and panthera sensu latu, other carnivorans characterized the middle 8 strani f. et al. ter, 2013; bellucci et al., 2021; stefanelli et al., 2021), which were replaced later by praemegaceros solilhacus and dama clactoniana (e.g., sardella et al., 2006; breda & lister, 2013; breda et al., 2015). the red deer appears in europe during the epivillafranchian (bermúdez de castro et al., 1997; iannucci et al., 2021 and reference therein), but its evolutionary history is still unclear. general consensus was reached in recognizing the simpler antler morphology of earlier forms, but different opinions on the validity and relationships of subspecies persist. for instance, based on the fossil record from the area of rome, four different chronosubspecies were instituted: cervus elephus acoronatus, cervus elephus eostephanoceros, cervus elephus rianensis and cervus elephus elaphus (leonardi & petronio, 1974; di stefano & petronio, 1992, 1993; di stefano et al., 1998; di stefano & petronio, 2002). one of the most abundant group of the middle pleistocene ecosystem is hippopotamuses, but there are conflicting opinions on their systematics and evolutionary history (e.g., caloi et al., 1980; mazza, 1991, 1995; mazza & bertini, 2013; van der made et al., 2017). however, hippopotamuses together with proboscideans and rhinoceroses were among the largest terrestrial mammals in galerian and aurelian assemblages. the proboscideans are well diffused across europe during the middle pleistocene. the earliest record of the straight tusked-elephant palaeoloxodon antiquus, attributed to epivillafranchian, was attested at vallparadìs estació, but this attribution was recently questioned (bellucci et al., 2015 and reference therein). however, the straight tusked-elephant is a very common element of galerian and aurelian assemblage (e.g., moncel et al., 2020a; abruzzese et al., 2016; rocca et al., 2018; rocca & aureli, 2020; stefanelli et al., 2021), until its disappearance, probably occurred during the early late pleistocene (mecozzi et al., 2021b and reference therein). another important biochronological marker for the galerian is the earliest dispersal of mammuthus trogontherii recognized at ponte galeria fu, which replaced the villafranchian species, mammuthus meridionalis (bellucci et al., 2015). rhinoceroses are represented by three taxa: stephanorhinus hundsheimensis, stephanorhinus hemitoechus and stephanorhinus kirchbergensis. the latter is quite sporadic in mammal communities, with a few specimens recorded at the middle pleistocene sites of visogliano (mis 13-10; pandolfi, 2013), ponte molle (mis 13; mecozzi et al., 2021) and tor di quinto (mis 13; pandolfi & marra, 2015). the earliest occurrence of s. hundsheimensis is attested during the late villafranchian (ballatore & breda, 2013 and reference therein), but its last occurrence needs to be clarified. pandolfi et al. (2018) attributed a few postcranial elements from grotta romanelli (lecce, southern italy) to hundsheim rhinoceros, hypothesizing a middle pleistocene age (~0.6 ma) for the levels k-i of this deposit. nevertheless, the lowermost levels of grotta romanelli have been historically referred to early late pleistocene because it directly overlies a tyrrhenian beach deposit (level k, mis 5e). with the aim to define a more accurate chronological scheme for the sequence of this key site, a new the importance of the italian territory and provides a revision of the pre-modern human fossil record from this region, updating the information previously reported in the “catalogue of italian fossil human remains from the palaeolithic to the mesolithic” (alciati et al., 2005). by the beginning of the middle pleistocene, the earliest acheulean homo heidelbergensis groups spread through europe. a site of particular interest is notarchirico (southern italy), where the earliest evidence of acheulean settlement in italy has been studied and placed even further back in time (moncel et al., 2020a). at notarchirico, four occupation levels have been unearthed, including one with bifaces dated through 40 ar/ 39 ar on tephras and esr on bleached quartz, that enable to place the occupation between 695 and 670 ka (mis 17), almost coeval with the moulin-quignon and la noira sites (france)(moncel et al., 2020a). as moncel et al. (2020a) pointed out, during the early middle pleistocene homo heidelbergensis groups arrived in europe, where they were exposed to “challenging environmental conditions, which may have stimulated new cultural responses”. the diversity of tools and activities observed at notarchirico, moulin-quignon and la noira sites shows that the north mediterranean was populated by adaptable hominins during this time. in particular, at the mis 17/mis 16 transition (670 and 650 ka), a very rapid expansion of shared traditions over western europe has been documented (muttillo et al., 2021). it must be stressed that the lithic samples over this period have been studied with different theoretical/methodological approaches preventing a comprehensive discussion. for instance, different approaches have been used even for the study of artefacts collected in distinct stratigraphical units of the same site (muttillo et al., 2021 and reference therein). however, as stated by muttillo et al. (2021), the technical behaviors documented during the early middle pleistocene (between mis 17/16 and mis 12) in the italian peninsula are extremely diversified. finally, the authors highlighted how a homogeneous and comprehensive study of all italian lithic samples of this period is required as a starting point to perform a large comparison of the various industries of the italian peninsula and also to evaluate them in a broadest european context. middle pleistocene lithic assemblages of europe also show a great variability in technological and typological characteristics (wiśniewski, 2014; malinskybuller, 2016; villa et al., 2016; picin, 2017). no general consensus was reached on how to interpret of this variability, especially in relation with the lower-middle paleolithic transition (lmpt) occurred during the middle pleistocene (mis 9-8) (malinsky-buller, 2016). the lmpt is marked by the passage from biface production to levallois technology (malinsky-buller, 2016). a recent large revision carried out by moncel et al. (2020b), suggests that the emergence of the middle paleolithic is older than generally supposed, and it can be referred to mis 12. in addition, the authors highlight that during the early middle paleolithic other technologies were also used. an important question rises about why the levallois technology became the dominant technological strategy of the middle paleolithic from the mis 9, which needs to be investigated (moncel et al., 2020b). the early human presence in the italian peninsula, pleistocene ecosystems as hyaena prisca, canis mosbachensis, cuon alpinus, meles meles and lynx pardinus (caloi & palombo, 1983; palombo & sardella, 2007; palombo et al., 2008, 2009; mecozzi et al., 2017, 2020a, b, 2021d; mecozzi, 2021). another important faunal renewal took place ~0.3 ma (mis 9), marking the beginning of the aurelian mammal age, where the last villafranchian representatives and few galerian taxa disappeared, replaced by new modern-like species such as the wolf canis lupus, the bears ursus arctos and ursus spelaeus, megaloceros giganteus, as well as the brown hare lepus europaeus (gliozzi et al., 1997, di stefano et al., 1998; palombo et al., 2002). the most famous italian local fauna of the torre in pietra fu is that of the iconic site of la polledrara di cecanibbio (marano et al., 2021). in france, early aurelian assemblages can be related to the biochron mnq24, characterized by the first occurrence of saiga tatarica (never recorded in italy), ursus spelaeus, capra ibex and coelodonta antiquitatis (sardella, 2007 and references therein). important early aurelian french assemblages are recorded at lunel viel and coudoulous i (brugal et al. 2021; fernandez et al. 2021). interestingly, bioclimatic models indicate that the palaeoecological requirements of species were very similar between the different faunal associations of the french locality of coudoulous i, and that -while significant climatic changes occurredthey prevented a complete species turn-over. this is in accordance with what observed in central italy, where similar herbivorous mammals adopted similar palaeoecological adaptations during mis 15 and during mis 11 (strani et al., 2021). the climatic deterioration occurred during the last 0.3 ma provided the ecological basis for the appearance of the cold-stage fauna generally known as mammuthus -coelodonta faunal complex, which characterized the late middle and late pleistocene of the northern hemisphere (kahlke, 1999). in the italian peninsula, this cold adapted faunal complex was recorded only during the late pleistocene, but the record of mammuthus primigenius and coelodonta antiquitatis is quite poor. in french, these taxa appeared during the late middle pleistocene, where probably favorable climatic condition established earlier (palombo & valli, 2004). in sum, the northern mediterranean area, allows for the in-depth study of how the climatic shift of the middle pleistocene influenced the palaeocommunities both in terms of evolution and composition of mammal taxa. 3.3. middle pleistocene human populations the middle pleistocene witnessed some important events in the history of human evolution. the italian human presence is documented by a rich fossil record and archaeological evidences found in a number of deposits (e.g., belli et al., 1991; piperno, 1999; manzi et al., 2001; scott & gibert, 2009; manzi et al., 2011; aureli et al., 2012; gallotti & peretto, 2015; peretto et al., 2015; moncel et al., 2019, 2020a,b). the italian peninsula has an important role in the study of the european middle pleistocene human populations, especially for the emergence of the mode 2 technology and the dispersal of homo heidelbergensis and homo neanderthalensis. buzi et al. (2021) confirms 9 an overview of the middle pleistocene in the north mediterranean region 10 strani f. et al. in addition to the fragmentary femur collected from the upper levels of notarchirico (moncel et al., 2020a and reference therein), is documented at isernia la pineta (mis 15, isernia, southern italy) by an isolated deciduous incisor (peretto et al., 2015). fontana ranuccio (frosinone, central italy) can be considered one of the most important sites, with 4 isolated human teeth, many vertebrate taxa and tools (biddittu et al., 1979; segre & ascenzi, 1984; rubini et al., 2014; zanolli et al., 2018; grimaldi et al., 2020). palaeoecological data from the fontana ranuccio site provide new information on the environments occupied by middle pleistocene homo in the italian peninsula. dietary adaptations of the ungulate community and of small mammal taxa suggest that homo populations occupied a region characterised by widespread wooded environments, and with grasslands inhabited mostly by groups of large ungulates, as attested by the diverse types of dietary behaviours observed in this group, with a relative dominance of cervids displaying a browsing or mixed diet (strani et al., 2018), and by enamel isotopic data (strani et al., 2019). harsher climatic conditions during adverse seasons may had played a key role, driving ungulates that needed a large amount of food intake, such as the large-sized aurochs (bos primigenius), to feed also on sub-optimal resources (strani et al., 2018). another important locality for human evolution is ceprano (mis 11, frosinone, central italy), where a partial cranium was historically discovered (manzi et al., 2001; manzi, 2016; di vincenzo et al., 2017). this specimen, recently revised, is ascribed to homo heidelbergensis by manzi (2016). finally, of considerable interest are the fossils recovered from the end of the middle pleistocene from altamura (bari, southern italy) and saccopastore (rome, central italy). the first site includes a probably complete skeleton with a cranium embedded in calcite concretions attributed to homo neanderthalensis (lari et al., 2015; di vincenzo et al., 2019). the latter yielded two nearly complete crania of h. neanderthalensis, saccopastore 1 and saccopastore 2 (sergi, 1944, 1948, 1962; bruner & manzi, 2006, 2008). the age of the deposit was historically attested to the last interglacial, but a recent reassessment of the aggradational succession in the area of rome suggested an oldest chronology (mis 7, marra et al., 2015). 4. conclusion the roots of “modern” terrestrial ecosystems in the mediterranean region can be placed in the middle pleistocene, when global climate patterns strongly conditioned the european vegetational landscape changes and those in the large ungulates and carnivoran guilds. however, the gap of knowledge or not up-to-date information from some historical middle pleistocene keylocalities of the mediterranean region is a major concern for quaternary research. in italy for instance, many works were published during the xx century on noteasily accessible local journals, and some materials were never formally described, limiting the available information on middle pleistocene quaternary ecosystems. the literature revision of historical palaeontological and archaeological works can help to obtain a more comprehensive framework of human and other mammals’ evolution. furthermore, historical museum collections such as those partially studied during the xx century, represent a palaeontological and archaeological heritage with significal scientific and socio-cultural value (demiguel et al., 2021). these collections are of great importance to describe unpublished material or reevaluate the information of the published ones, as for instance the fossils from the middle pleistocene localities of fontana ranuccio (conti et al., 2021), fontignano (iannucci et al., 2021), lunel-viel (brugal et al., 2021) and ponte molle (mecozzi et al., 2021). overall, the archaeo-geo-palaeontological evidence from italy and france presented in this volume is of particular interest to depict an accurate reconstruction of the modern terrestrial communities’ changes toward the contemporary world of the holocene. acknowledgements we are grateful to alpine and mediterranean quaternary for their interest and predisposition in publishing all these scientific contributions in this special volume, in particular to dr. ilaria mazzini and prof. marco peresani, for their assistance and dedication, and all the staff members of the journal. we also thank all the reviewers that through their comments and suggestions helped authors to improve the original papers. finally, we would like to thank the authors for their participation in this volume and for their contributions. we thank the many colleagues with whom we have collaborated in the study of the middle pleistocene, especially daniele aureli, luca bellucci, fabio bona, marzia breda, jacopo conti, antonio curci, camille daujeard, alessio iannucci, dawid adam iurino, marie-hélène moncel, alfio moscarella and roxane rocca. references abruzzese c., aureli d., rocca r. 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(2014) the beginnings and diversity of levallois methods in the early middle palaeolithic of central europe. quaternary international, 326327, 364-380. zanolli c., martinón-torres m., bernardini f., boschian g., coppa a., dreossi d., mancini l., martínez de pinillos m., martín-francés l., bermúdez de castro j.m., tozzi c., tuniz c., macchiarelli r. (2018) the middle pleistocene (mis 12) human dental remains from fontana ranuccio (latium) and visogliano (friuli-venezia giulia), italy. a comparative high resolution endostructural assessment. plos one, 13(10), e0189773. ms. received: may 4, 2021 revised: june 2, 2021 accepted: june 22, 2021 available online: july 3, 2021 16 sess 1_160211.pub il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 new archaeological and geomorphological markers along the istrian coasts (croatia) and their relations with relative sea level changes stefano furlani1,2, sara biolchi2,3, rita auriemma4, giorgio tunis2, franco cucchi2 & fabrizio antonioli5 1dipartimento di geografia “g. morandini”, università degli studi di padova, italy 2dipartimento di geoscienze, università degli studi di trieste, italy 3dipartimento di scienze della terra, università degli studi di modena e reggio emilia, italy 4dipartimento di beni culturali, università di lecce, italy 5enea, acs, roma, italy corresponding author: s. furlani <sfurlani73@gmail.com> abstract: furlani s. et al., new archaeological and geomorphological markers along the istrian coasts (croatia) and their relations with relative sea level changes. (it issn 0349-3356, 2011) new data on archeological remains and coastal morphologies have been used to refine published data on the lateholocene relative sea-level change along the northeastern ardriatic coasts. data have been compared with predicted curves, in order to detail the tectonic evolution of the studied area. riassunto: furlani s. et al., segnalazione di nuovi indicatori archeologici e geomorfologici lungo la costa istriana (croazia) e correlazione con le variazioni relative di livello marino. (it issn 0349-3356, 2011) le variazioni di livello marino tardo-oloceniche lungo le coste nordorientali dell’adriatico sono state dedotte da una serie di nuove misure effettuate su indicatori archeologici e geomorfologici sommersi. i dati raccolti sono stati comparati con le curve predette di risalita del livello del mare. key words: sea level changes, late-holocene, geoarchaeology, istria, northeastern adriatic parole chiave: variazioni di livello marino, tardo-olocene, geoarcheologia, istria, adriatico nordorientale the gulf of trieste and the istrian coasts have been extensively studied during the last decade (fouache et al., 2000; antonioli et al., 2004, 2007; faivre and fouache, 2003; faivre et al., 2011; furlani et al., 2011). neverthless, many sites remain unstudied from the point of view of sea level changes. cited authors reported along the limestone coasts between the gulf of trieste (italy) and istria (croatia) the quasi-continuous occurence of a submerged marine notch at a depth ranging between –0.5 m and –2.8 m, while roman age archaeological remains were measured at depths usually deeper than the altitude of the notch. we aim at detailing the late-holocene, in particular since roman-age, tectonic behaviour of the studied area following the methodological steps suggested first by antonioli et al. (2007). 1. study area from a geodynamical point of view, the study area belongs to the external dinarides. it is characterized by a diffuse nw-se orientation of the tectonic structures. along the northeastern adriatic coast crop out limestones belonging to the adriatic carbonate platform and spanning in time from lower jurassic fig. 1. the study area and the surveyed sites l’area di studio con i siti indagati 35 37 36 (toarcian) to eocene (vlahović et al., 2005). previous works recognized the occurrence in the ne adriatic sector of a nw tilting along different geological time scales: pendulum data (braitenberg et al., 2005), geomorphological markers (antonioli et al., 2004, 2007), archeological markers (degrassi et al., 2008) are evidence of recent tilting, while geophysical data (busetti et al., 2010), structural data (carulli et al., 1980) and gravity modeling (coren et al., 2006), indicate that the tilting is regional and long lasting. moreover, the dataset suggests that the southern side of the gulf has subsided, at least since roman time (about 0.6 mm/y), while the northern side has subsided during the holocene, probably faster than the southern side (up to 1.99 mm/y, even if probably this value is mainly due to high sedimentation rates), following the aforementioned tilting (furlani et al., 2011). 2. the investigated sites and their significance on local tectonics six new submerged archaeological and geomorphological markers have been surveyed, one in italy and the remnants in istria (croatia). in particular: 1) submerged structure at sistiana (trieste, italy). the functionality of the structure is not completely understood yet, since it is inclined toward the sea. since the presence of quarries, which are active since roman age, located just near the site, it could be a “slide” to charge limestone blocks on the ships. its altitude ranges between -1.0 m and 5.0 m; 2) coastal quarry at palud (pula, croatia). the structure shows the proofs of human quarrying on limestone blocks. the base level of the quarry is covered by cementitium (maybe used to level off the pavement) and it is at about -0.2/-0.3 m m.s.l. fig. 2,submerged dock at barbariga il molo sommerso di barbariga s. furlani et al. 37 ms. received: testo ricevuto il offshore there is another human-made basement; 3) submerged “path” at kolone (bale, croatia). a submerged path, at about -1.5 m m.s.l., connects the coast to a small island. it is about 100 m long; 4) submerged dock at barbariga (croatia). the state of conservation is bad. the altitude of the structure is about -1.5 m; 5) submerged beachrock at brijuni. its depth ranges between about -5.0 and about -1.5 m. its morphology suggests that the structure is a beachrock; 6) coastal quarry at sekovac (premantura, croatia). the structure evidences the proofs of human quarrying on limestone blocks. the altitude is similar to the quarry located at palud. the comparison between published and these new data refines the knowledge on late holocene sea level change in istria. the large number of structures already surveyed in the area allows to usefully integrate the available data, despite the bad state of conservation of the studied markers and the large uncertainty on their functionality. the most useful sea level marker is the roman dock at barbariga. the mean values of the tide and pressure-corrected archaeological measurements suggest a depth of -1.6±0.5 m for the 2 ky bp sea level (roman age – i sec. a.d.). considering the recent position of the submerged road at bale, the same relative sea level rise rate seems to affect even the area located toward north. the altitude of the quarries represents an upper limit for the roman age sea level, however values agree with the other considerations. comparison between the position of the submerged markers and the predicted values of sea level rise for the northern adriatic sea details data collected by previous authors and confirms the negative tectonic rate (-0.7/-0.8 mm/yr) for the whole studied area. acknowledgements we are kindly grateful to dr. sandro duijmović and eduard kolić of the brijuni national park (croatia) for the surveyings along the coasts of the park. references antonioli f., carulli g.b., furlani s., auriemma r. & marocco r. (2004) the enigma of submerged marine notches in northern adriatic sea. quaternaria, 8, 27–36. antonioli f., anzidei m., lambeck k., auriemma r., gaddi d., furlani s., orru’ p., solinas e., gaspari a., karinja s., kovacic v. & surace l. (2007) sea level change during holocene from sardinia and northeastern adriatic (central mediterranean sea) from archaeological and geomorphological data. quaternary science reviews, 26, 2463–2486. braitenberg c., nagy i., romeo g. & taccetti q. (2005) the very broad-band data acquisition of the long-base tiltmeters of grotta gigante (trieste, italy), journal of geodynamics, 41, 164-174. busetti m., volpi v., nicolich r., barison e., romeo r., baradello l., brancatelli g., giustiniani m., marchi m., zanolla c., nieto d., ramella r. & wardell, n. (2010) dinaric tectonic features in the gulf of trieste (northern adriatic), proceedings of the “27° convegno nazionale del gruppo nazionale di geofisica della terra solida (gngts)”, trieste (italy), 6-8 october 2008. bollettino di geofisica teorica e applicata, 51 (2, 3), 117-128. carulli g.b., carobene l., cavallin a., martinis, b. & onofri r. (1980) – evoluzione strutturale plioquaternaria del friuli e della venezia giulia, contrib. prelim. realizz. carta neotettonica d’italia, pubbl. 356 del prog. finalizz. geodinamica, unità operat. 6.2.10, 489-545. coren f., marson i., creati n., prodan m., palmieri f. & zanolla, c. (2006) – structural setting of the trieste area from gravity modeling, bollettino di geofisica teorica ed applicata, 47 (4), 549-555. degrassi v., furlani s., scotti f.m., melis r., antonioli f. & fonda, g. (2008) – strutture portuali di via dei cavazzeni (trieste): indicazioni sul livello del mare, terre di mare. l’archeologia dei paesaggi costieri e le variazioni climatiche. a cura di: r. auriemma, s. karinja, udine, atti del convegno interreg internazionale di studi, trieste, 8-10 novembre 2007, 275-281. faivre s. & fouache e. (2003) some tectonic influences on the croatian shoreline evolution in the last 2000 years. zeitschrift für geomorphologie nf 47 (4), 521-537. faivre s., fouache e., ghilardi m., antonioli f., furlani s. & kovacic v. (2011) relative sea level change in istria (croatia) during the last 5 ka. quaternary international, in press. fouache e., faivre s., dufaure j.-j., kovacic v. & tassaux f. (2000) new observations on the evolution of the croatian shoreline between pore_c and zadar over the past 2000 years. zeitschrift für geomorphologie supplement-band, 122, 33-46. furlani s., biolchi s., cucchi f., antonioli f., busetti m. & melis r. (2011) tectonic effects on lateholocene sea level changes in the gulf of trieste (ne adriatic sea, italy). quaternary international. in press. vlahovic i., tisljar j., velic i. & maticec d. (2005) evolution of the adriatic carbonate platform: paleogeography, main events and depositional dynamics, palaeogeography, palaeoclimatology, palaeoecology, 220, 333-360. new archaeological and geomorphological markers along ... january 15, 2011 15 gennaio 2011 amq64 panarello 3 post corr.pub � �� � �available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 30 (2), 2017, 137-154 fifteen years along the “devil’s trails”: new data and perspectives adolfo panarello 1, maria rita palombo 2, italo biddittu 3, paolo mietto 4 1 dipartimento di scienze umane, sociali e della salute, università studi cassino e lazio meridionale, cassino (fr), italy 2 dipartimento di scienze della terra, sapienza università di roma, igag_cnr, roma, italy 3istituto italiano di paleontologia umana, convitto nazionale regina margherita, anagni (fr), italy 4 dipartimento di geoscienze, università degli studi di padova, padova, italy corresponding author: a. panarello <panarello@unicas.it> abstract: on march 2003, the discovery of human fossil footprints on the volcanic ashes of the north eastern slope of roccamonfina volcano was announced to the world. they were dated to through 40ar/39ar to 349±3 ka. for this reason they are still among the oldest ichnological issues known up to now. furthermore, they are, more specifically, among the rarest ichnological evidence left by middlepleistocene man. these fossil footprints are not randomly located but, on the contrary, they are patterned to form at least two trackways (called "trackway a" and "trackway b") whose general shapes have not found comparisons in the world so far. both trackways branch off from another unique fossil structure, which is the oldest human fossil pathway identified so far. all directly collectable data from these structures has been analysed and published in a series of reports. although the high antiquity of the footprints has been for a long time the leitmotiv and the most attractive element for the media and scientists, its true paleontological power must be seen in its capacity to provide significant clues about the everyday behaviour and the environmental context of homo heidelbergensis during the middle pleistocene and whose remains have been found on very few sites of the same age. unfortunately, despite the worldwide media clamour and the great attention of the scientific world, despite the publication of many reports, the geosite is still not adequately protected and promoted and is at risk of losing a significant part of its paleontological and touristic potential. nevertheless, scientific research, in spite of great difficulties, goes on. here we report about the state of what has already been done by scientists and what still needs to be done, pointing out that no more time can be wasted to preserve one of the most important and ancient human ichnosites ever discovered. keywords: roccamonfina, devil's trails, ciampate del diavolo, fossil footprints, hominids, paleofauna, homo heidelbergensis 1. introduction the “ciampate del diavolo” palaeontological site (n41°19.954’ e14°01.488’) (fig. 1) lies on the northeastern slope of the roccamonfina volcano. before its discovery, on august 4th, 2001, only a legend existed telling the story of an uncanny walker who had left his footprints on the still burning lava after trampling on it. another local historian supposed that they might have been left by some ancient italic people (iulianis, 1986). indeed, local people, probably due to their lack of scientific knowledge, thought that only a supernatural being could have walked on the burning lava without burning itself. actually, the ground is not made up of lava but of tuff and this was the first remarkable evidence, which was noted by the discoverers (adolfo panarello and marco de angelis). as it is well known, tuff is the result of the consolidation of a pyroclastic chaotic deposit. anyway, although not completely convinced, local people accepted this explanation and passed it down from generation to generation, up until 2001. previously some local scholars had tried to find a scientific explanation of those "strange" footprints, but none of them succeeded (panarello, 2005). on march 13th, 2003, after all the necessary surveys, tests and studies, the scientific team led by paolo mietto (university of padua) announced to the world the discovery of what were the oldest fossil footprints attributable to some exemplars of the genus homo so far. they were preserved on a brown leucitic tuff (blt) formation, which was preliminarily dated between 385 and 325 ka (mietto et al., 2003). during the first surveys, carried out during the two preceding years, at least 46 footprints and at least one handprint had been detected. they were organized in at least two trackways (called "trackway a" and "trackway b") and associated with fossil prints of other human body anatomical parts and with a still unspecified number of animal footprints. most of this was published in the first official reports by avanzini et al. (2008). after some fieldwork, from 2005 to 2010, within the main palaeontological site, located near the village of "foresta" (municipality of tora e piccilli, caserta province, central italy) many other signs were detected and they are still under study. in addition to other possible animal footprints, an astonishing structure was also found, which resembled paths left in the snow by walkers moving casually. this structure was partially altered during quarrying activities in historical times, but preserved enough details to be objectively studied. actually, two doctoral works have permitted a rigorous and comprehensive detection and interpretation of the whole geology of the site (santello, 2010), in addition to the morphology and structural evolution of each of the ich� � �� � � 138 panarello a. et al. nites and pseudo-ichnites (panarello, 2016a) found during the field work carried out by the research team led by paolo mietto (university of padua). recently, an official report about the aforementioned structure, which was thought to be a fossil prehistoric path, has been published: it is actually a middle-pleistocene pathway from which at least two trackways of human fossil footprints branch off (panarello et al., 2017b). over the past two years, specific research has started on palaeoanthropological, palaeozoological and palaeo-biomedical aspects. the ichnosite of "foresta" is, in truth, exceptional because it allows to observe and to study on the same site the following aspects: it is possible to carry on a detailed geological, stratigraphical and radiometrical analysis of the substrate; there are a great number of human and animal fossil footprints, which are preserved on a very steep slope (up to 80%); human footprints are organized in gait patterns that cannot be compared to similar ones anywhere else so far; human footprints are associated with fossil prints of other human body anatomical parts (calves, possible gluteus, etc.), which have not been found elsewhere up to now; there is at least one human handprint, which is located in the open air and not in a cultural context; there is the oldest fossil pathway known up to now in the world; it preserves within its length (over 50m) both human and animal fossil footprints oriented in different directions; there are fossil footprints of palaeofauna; finally, the "ciampate del diavolo" ("devil's trails") paleontological site is one the oldest ichnosites of the world and certainly one the most precious for the study of the behaviour and the body structure of european middle-pleistocene, likely homo heidelbergensis as suggested by the presence of remains of this species in the region, i.e. the ceprano skull (ascenzi et al., 1996, 2000; manzi et al., 2000, 2010, 2016; di vincenzo et al., 2017). in this paper we report on the state of the studies to file what has been done during last fifteen years and what must still be done in a scientific perspective and, especially, in the view of the preservation and promotion of this quite unique site (not started as yet), which must be considered as one of the most important in the entire world. 2. a unique site in the world 2.1 state of the art at present, the unearthed surface, made up of brown leucitic tuff (blt) is about 2000 square meters wide. so far, 8 stratigraphic units have been surveyed. they are numbered from ls01 to ls08 and are related to pyroclastic flows of variable magnitude, composition and dating. the trampled level is ls07. it is separated from ls08 by an interstructure formed of thin, variable granular materials that facilitated the preservation of fig. 1 location of the “devil's trails” (“ciampate del diavolo”) paleontological site (roccamonfina volcano area, central italy). � �� � � 139 devil’s trails: the state of art fossil footprints during the following pyroclastic flow which put in place ls08 geological unit (santello, 2010; panarello, 2016a, 2016b) (fig. 2). various dating of ls07 are available. the first of them, at 385-325 ka, was carried out using the k/ar method (luhr & giannetti, 1987; appleton, 1972; giannetti, 1979a, 1979b; radicati of brozolo et al. 1988; ballini et al., 1989a, 1989b, 1990; cole et al., 1992; de rita & giordano, 1996). a more punctual dating at 345 ± 6 ka was provided by scaillet et al. (2008) through 40ar/39ar method. the last and most accurate radiometric 40ar/39ar dating, which was carried out on both ls07 and on ls08 layers, was done by lisa santello together with the scientific team led by paolo mietto. it provided a dating at 349 ± 3 ka (santello, 2010: 68-69). the possibility of having a dating for both the trampled layer and for what sealed it, enables scientists to precisely establish the chronological extremes of footprints within a very narrow range, which is slightly younger than the termination iv (337 ka) and which is correlated with late mis 10. this fact is not common to all the other ichnosites of hominids known in the world up to now and this must be considered as another reason for the uniqueness of the "devil's trails" site. moreover, between ls07 and ls08, no palaeosoils have been found suggesting that not much time passed between the pyroclastic flows, which put these geological units in place. from a taphonomic point of view, the lithification of the layer ls07, which allowed the fossilization of the footprints, is due to a zeolitization process (mietto et al., 2003), which was preceded by a quite common cooling and drying process of the surface. this is well documented by the presence of mud cracks flanking fossil footprints in many places (fig. 2). the trampled surface was also protected by a sort of protective debris blanket, which was created by the fallout materials before the following pyroclastic flow took place. finally, the exploration and analysis of other blt deposits which are distant from the "devil's trails" site and which are located on the eastern and southern sides of the volcano, also allowed the clarification that the zeolitization of the pyroclastic deposit did not occur homogeneously. so that inconsistent levels alternate with others, which have a lithic consistence, and this inhomogeneity has favoured the preservation of fossil footprints and has also provided the chance to see them again after their reexposure caused both by natural and anthropic agents. the human fossil footprints are aligned to form two different trackways (called "trackway a" and "trackway b") (figs. 3, 4), both descending the slope and both generally oriented toward south-east. the very singular shapes of these trackways show evident attempts to manage the steep incline, which sometimes appear successful and sometimes do not. the "trackway a", in fact, has a "z"-shaped pattern because the trackmaker was smart at judging the steep and slippery slope and in choosing the best route to safely descend it. on the contrary, trackmaker b chose a difficult route; therefore, he slipped and fell. during his attempt to regain balance, he left the print of his left hand and of other parts of his body on the still soft and already moderately cooled substrate (avanzini et al., 2008). no other hominid ichnosite has an incline comparable to that of the "devil's trails" site. in some zones, this fig. 2 a zone (red rounded), near trackway a, in which mud-crack are preserved on the original prehistoric surface. � �� � � � fig. 4 trackway b, southern view: 3d generated zenital image, scale bar 2 m (a); contour lines 5 mm (b). 140 panarello a. et al. fig. 3 trackway a, southern view: 3d generated zenital image, scale bar 2 m (a); contour lines 5 mm (b). � �� � � incline exceeds 30° and this means that the two trackmakers had to use good judgement to maintain balance during their risky downhill slope descent. this allows us to infer, through the study of gait patterns, that the trackmakers had the same pelvis structure as ours, that they were habitual bipeds and that they were fully able to make conscious and developed behavioural choices. actually all the footprints belonging to both "trackway a" and "trackway b" clearly point out evident step crossings and other foot adjustments to manage natural constraints or to test the ground in search of more stable support and balance during walking. moreover, the left hand of trackmaker b is cleverly used to regain lost balance by touching the upward sidewall flanking the long slippery slope (avanzini et al., 2008). similar evidence is not known elsewhere in the world nor other findings of handprints are known which can be safely considered completely free from cultural claims and which are located in a subaerial environment like that of the "devil's trails" site. finally, in the distal part of trackway b, the deep prints of calves and of other possible hands and of a possible gluteus are clearly visible. this recent evidence is still under study. the most recent and detailed photogrammetric surveys and the 3d models (fig. 5) created by scientists permitted to confirm the actuality of all the footprints (46, at least) of both trackway a and b. on the contrary, they have highlighted that some stratigraphical problems about trackway c still occur. so this trackway has been put under study (panarello et al., 2016; panarello and mietto, 2017) once again. at least four more human footprints were found in the western end of the site. they are still under study and will be published as soon as their analysis is complete. other partially altered human and animal footprints have been found within the space of the prehistoric pathway that dominates the tuff slope and from which the two trackways a and b branch off. studies about this prehistoric route, already noticed in 2005, has recently been completed: it proved to be, actually, the oldest human fossil pathway ever discovered so far. to date it is not comparable to other similar elements anywhere in the world both for antiquity and for the duration of the settling dynamics it suggests (panarello, 2016a, 2016b; panarello et al., 2017). the footprints of foresta, the so-called "devil's trails" (or "ciampate del diavolo") are among the oldest human fossil footprints ever discovered outside africa. in africa, only the footprints of laetoli (leakey and hay, 1979; meldrum et al., 2011; deino, 2011; masao et al., 2017), those of ileret (bennett et al., 2009), and those of koobi-fora (behrensmeyer & laporte, 1981; bennett et al., 2009) are certainly older, as well as in europe those of happisburg (norfolk, uk) (ashton et al., 2014). recent data suggest that also the single footprint found of terra amata (france) could be older (de lumley et al., 2011). many other ichnosites of hominins are known all over the world (lockley et al., 2008; bennett & morse, 2014; panarello, 2016b) and some of them are very interesting, i.e. that of willandra lakes, southeastern australia (webb et al., 2006; webb, 2007), but none of them has the same antiquity of the aforementioned sites. the sapienza university of rome recently announced the discovery of new ancient hominid ichnosite, dated to about 800 ka, in eritrea (https:// www.uniroma1.it/it/node/26082 2.2. new data contemporaneously with the study of human footprints, new lines of research have been developing over the last couple of years aimed at providing a new radiometric chronological constraint (panarello et al., 2017b) to the site, and to investigate the environmental context. specifically, archaeological surveys were performed to provide further evidence of the presence of homo heidelbergensis inside and around the roccamonfina volcanic area. furthermore, since 2016 new analysis of the palaeosurface has begun to detect vertebrate footprints fig. 5 trackway a: 3d generated depth map (zenital and transversal images) of the human fossil footprint called a25 (right foot); contour lines: 1 mm; scale bar: 10 cm. 141 devil’s trails: the state of art � � �� � � useful to giving some clues about the palaeofauna living in the same area and frequenting the site of "devil's trails" paleontological site. finally, a first analysis about the sex and the body mass of human trackmakers has been started, awaiting more in-depth physical study. 3. trackmaker's identities: new research for new clues 3.1. archaeological investigations since the second half of the nineteenth century there is known evidence of an ancient human presence in northern campania and in molise, which is documented by lithic tools, generically attributed to the "stone age" (nicolucci, 1871). the first citation about the finding of a classic acheulean biface tool in situ was given in 1876 by luigi pigorini (pigorini, 1876). although mistakenly doubting about its belonging to a generic "periodo archeolitico" (“archaeolytic period = lower palaeolithic”) he described one of the most classic italian biface stone tool with quite unusual dimensions (mm 233 x 105 x 75; fig. 6), which had been found «alla profondità di quasi sei metri tra uno strato di argilla e uno di ghiaia, cavandosi le fondamenta di una casa colonica presso il villaggio di ceppagna» ("at a depth of about six meters between a layer of clay and a gravel, breaking the foundations of a farmhouse in the village of ceppagna”) (pigorini, 1876), a small village lying only 17 km far from the “devil’s trails” paleontological site. for this reason, a systematic exploration of the palaeontological site and its surroundings has been started in 2014, in search for evidence able to confirm the first belief that trackmakers could have been some �homo heidelbergensis individuals and thus specifying also their cultural identity. researches carried out up to now have enabled us to identify some artifacts/implements scattered on the soil surface that, at the moment, cannot be attributed to any precise chronological phases. on the contrary, some more interesting data may be provided by one basalt artifact which was found right inside the “devil’s trails” palaeontological site, in the matrix, called �, between the ls07 and ls08 geological layers, i.e. between the trampled surface (ls07) and its sealing layer (ls08) (santello, 2010) (fig. 7, fig. 8). this lithic tool was accidentally uncovered by quarrymen who enlarged, in historical times, the original prehistoric surface which has recently been interpreted as a walking space located upward of the trackways a and b of human fossil footprints (panarello, 2016a; panarello et al., 2017b), but it had not been noted before the most recent field works by paolo mietto’s scientific team during the years 2013-2015. the 142 panarello a. et al. fig. 6 the stone biface from ceppagna (after pigorini, 1876). fig. 7 detail of the position, in geological stratigraphy, in which the basalt core has been found (reworking after santello, 2010). � �� � � � same artifact was left in situ up to june 2016, when it was extracted with the maximum care in order to register its exact stratigraphic location. the entire surface of the lithic tool preserves an altered two-colour patina. the weathered part, which has been exposed to the light and rain, has acquired a dark colour (dark grey hue 5y 4/1) and a slight lustration whereas the side that was embedded in the ls07 sediments has a lighter colour (grey hue 5y 5/1) and a homogeneous patina with some traces of the sediments forming the layer. fresh fractures are not recognizable. the artifact, which can be classified between the cores, has concave surfaces for multidirectional removals. one of its sides (fig. 9) has the negative of 3 removals from a single percussion plane while one comes from the opposite plane. its lower face has centripetal removals on which the impact point is not clearly distinguishable (fig. 10). its section is flat convex. its maximum measurable dimensions are mm 52 x 45.50 x 42. its weight is 94 gr. 143 devil’s trails: the state of art fig. 8 “devil’s trails” paleontological site detail photos of the lithic core from “devil’s trails” paleontological site at the moment of its finding.scale bar: 10 cm. � �� � � � the use of basalt and hard materials of volcanic origin for the manufacture of similar tools is already known from the most ancient phases of palaeolithic technology in africa in the olduvai gorge (leakey 1971) and at melka kunturé (chavaillon & berthelet, 2004; chavaillon & piperno, 2004); in eurasia at dmanisi (celiberti et al., 2004; de lumley et al., 2005); in europe at bois-de-riquet in southern france (bourguignon et al., 2015). a direct comparison with some known evidence from central italy can be made with the stone tools from two palaeolithic sites located in the frosinone province, i.e. fontana ranuccio in anagni and pofi-cava pompi. at fontana ranuccio there is a level of pedogenized tufite with solifluction and ferritic crust containing abundant fossil fauna and lithic tools which have been dated at the lower palaeolithic and attributed to the acheulean facies (ascenzi et al., 1993). k-ar dating made on leucite crystals indicated for this site an age of 458 ka (biddittu et al., 1979). at the fontana ranuccio site remains of fauna are associated with lithic and bone industries: small and medium-sized flint tools are associ 144 panarello a. et al. fig. 9 the exposed side of the lithic core found between geological layers ls07 and ls08 (scale bar: 5 cm). fig. 10 the buried side of the lithic core found between geological layers ls07 and ls08 (scale bar: 5 cm). fig. 11 zenital photo of the space between the original position of the lithic core and the footprints of the middle sized ruminant artiodactyl. � �� � � 2005; hunt and lucas, 2007; lucas, 2007; milàn et al., 2007, 2015; noe-nygaard et al., 2007; oishi et al., 2002; bromley et al., 2 009; kim et al., 2009; neto-decarvalho, 2010; buynevich et al., 2011; aramayo et al., 2015) while tracks associated with volcanic deposits were mainly preserved in volcanic ash, rarely in volcanoclastic sediments (see e.g. johnson, 1937; lucas & schultz, 2007; meldrum et al., 2011). the best preserved mammal footprints found to date at the foresta site have been detected on the subhorizontal surface, used as a route-way by homo heidelbergensis, bordering the pyroclastic flow slope (fig. 13). they belong to a middle sized ruminant artiodactyl (ichno-order artiodactipedida sensu vialov, 1966), as is clearly indicated by the elongated and wedge shape of the concave hyporelief of two hooves (medial digit iii hoof and lateral digit iv hoof), which are mirror images of each other, and show a convex, parabolic external outline, with a broader caudal part and angular distal edge, while the internal one is slightly concave. the ichnotaxonomy and trackmaker identification of artiodactyl tracks, especially those of ruminants, is however difficult because of a basic similar morphology of the foot among different taxa and the large variation in shape of footprints impressed by the same trackmaker in relation to the gait (causing the clouts to flex differently and spread apart) age and gender (affecting size and shape) (see e.g. cervipeda and pecoripeda ichnotaxa). the identification issues increase in the case of foresta footprints due to the presence of only two footprints, which are not placed in succession but side by side, nearly parallel to each other (the right better defined than the left), and show some intriguing features. both footprints show weakly convex clout walls, and markedly convergent hoof tips. subunguinus spaces are not visible, while callus pad impressions are hardly detectable on the right footprint, where the impressions of dewclaws, the small vestigial nails for digits two and five, are visible behind the tracks of the third and fourth digit, while dewclaw impressions are not well-defined in the left footprint. a narrow interdigital space is present in the right footprint, while in the left one the impression of third and fourth digits are superimposed, as the third would slide on the fourth. the size of footprints (length and breadth of about 5 and 3 cm respectively) may be consistent with that of either roe deer or chamois. the size may be consistent too with footprints of fallow deer females of young red deer individuals, though the latter usually show a more convex clout walls. the most intriguing features are, however, the presence of the dewclaw impressions combined with the footprint position, and the lack of divergence shown by lateral and medial hooves. dewclaw impressions may be present when deer slowly walk on a soft substrate, or by jumping roe deer and chamois. in the first case, however, impressions of left and right manus/pes alternate, while footprints left by a jumping roe deer they are not side by side, and impressions of third and fourth digit significantly diverge from each other. the hint feet of chamois, during racing and jumping, touch the ground side by side and in front of the forelegs, but the hooves diverge considerably and dewclaws leave their footprint distant from the third and fourth digit impressions. more data is ated with more rare basalt ones, medium-sized basalt and flint bifaces, numerous artefacts derived from bones of mammals with a particular choice on the use of palaeoloxodon antiquus diaphysis. at the same site four human molars have been found: they show morphological characteristics and chronology matching those of homo heidelbergensis (ascenzi et al. 1993). at the site of pofi cava pompi, during the extraction of "pozzolana" in the 1960s (fedele et al., 1962), human fossil ulna and tibia remains were found. they are associated with fossil fauna and rare lithic tools made up of flint and basalt. despite the absence of bifaces, the site of cava pompi show several similarities with that of fontana ranuccio because of the presence of small-sized flakes and bowls, and because of the use of basalt and animal bones for the manufacture of medium-sized artifacts (passarello and palmieri, 1968; biddittu and segre, 1978). the finding of the basalt tool inside the “devil’s trails” site on the same surface where human fossil footprints are preserved adds an important element which will certainly help to elaborate new hypotheses and to make new assumptions about the possible contemporaneity of the scatter of the precious tool along the prehistoric frequented pathways and about the possible significance of its typological aspect (the existence of a core also implies the presence of a hammerstone). another interesting feature is the position and distance of the core (1,0534 m) compared to the herbivorous footprints described in this work (fig. 11). it is, therefore, evident that more careful studies are necessary about the discovered stone tool with special attention to the micro-traces preserved on its surface. it is also necessary to go on investigating about the location of the finding paying maximum attention to the erosive processes of the layer ls07, in order to try to find other tools and generically cultural evidence strictly related to the trampled layer with the possible demonstration that human presence within the palaeontological site is exclusively proven by the well-known fossil footprints. 3.2. looking for vertebrate footprints the detection and identification of vertebrate footprints on the foresta palaeosurface is challenging due to the characteristics of the pyroclastic flow they are impressed on, and the alteration undergone by the top of the volcanoclastic deposit during its prolonged exposure to weathering agents (fig. 12). the features of footprints left by a trackmaker, indeed, strictly relate to the typology of the substratum (e.g. granulometry, water content, degree of cohesion, inclination of the impressed surface) that affect depth and shape of tracks, as well as to gait, body mass, gender, and age of trackmakers (see e.g. inter alios allen, 1997; bromley, 2001; milàn, 2007; manning, 2004; milàn & bromley, 2006, 2008; fanelli et al., 2007; marty et al., 2009; morse et al., 2013; platt & hasiotis, 2014). most quaternary vertebrate footprints and trackways have been reported from aeolian or coastal sandy deposits, some from swampy, muddy fluvio-lacustrine environments (see inter alios flor, 1989; lea, 1996; allen, 1997; quintana et al., 2001; fornos et al., 2002; lucas et al., 2002; morgan et al., 2002; scott, 145 devil’s trails: the state of art � �� � � needed to properly identify the trackmaker of artiodactipedida footprints found at the foresta site. among the other potential mammal tracks preserved in the study area on the pyroclastic flow slope, a short track way would be tentatively ascribed to a horse (hippipeda ichnotaxon, vialov, 1966). the track way consists of 3 deep rounded buds (fig. 14), crossing the human “trackway b” (avanzini et al., 2008; panarello, 2016c). the footprints are sub-circular in shape (the width is approximately equal to the length of the tracks, with convexly arched anterior (?) part and slightly expanding to nearly parallel outer margins extending posterior (?), but the caudal frog, characterising mot (?) horse footprints, is not detectable, suggesting extreme caution and more investigation before even any hypothetical identification. some problematic, badly preserved tracks, which have still not been analysed in detail, are present in the thin mud layer interbedded between the surface of the pyroclastic flow preserving the human trails and the overlain volcanic deposit. a couple of impressions apparently show some similarities to bear footprints (kowalski, 1961), especially known as regards cave bears ascribed by dietrich (2011) the new ichnogenus 146 panarello a. et al. fig. 12 “devil’s trails” site, images of paleosurface generated from 3d model: southern zenital view (a); close-up zenital photo of the area in the red box showing the alteration of the surface due to the exposure to weathering agents (scale bar: 140 cm) (b). � �� � � and species ursichnus europeus, but rarely reported from italian pleistocene sites (bocchini and coltorti, 1978). a track shows a sub-oval, roughly kidney-shaped large depression that would correspond to the manus with five small oval depressions along its convex edge perhaps corresponding to digit impressions. some pits in front of the “digit impression” would be claw marks that bear footprints usually have in front of the digits, especially when the prints are left on soft surfaces. however, due to the bad preservation and the uneven surface of the muddy layer, any identification of such traces as real footprints is, at the moment, highly speculative (fig. 15). it is worth noting, however, the high potentiality the foresta site has to provide significant clues enhancing our knowledge about the environmental context of homo heidelbergensis that inhabited the area during the middle pleistocene and whose remains have been found in a few sites, encompassing the age of the foresta one (e.g. cava pompi, passarello and palmieri, 1968; rubini et al., 2014; ceprano, manzi et al., 2010, manzi, 2016). 4. fear for the "devil's trails": remarks on the problems of preservation of the palaeontological site a careful and accurate analysis of the fossil footprint bearing surface re-exposed by both anthropic and, especially, by natural agents about 200 years ago (de angelis, 2009), was performed through a highly detailed photogrammetric survey. it revealed, also through 3d techniques, that a severe decay of blt is under way in many places of the "devil's trails" palaeontological site. middle-pleistocene human and animal footprints are very close to some of the most critical points, with a realistic imminent risk that the palaeontological evidence may be irreparably damaged. this aspect has been unambiguously communicated to the authorities responsible for the preservation of the geosite and to the schol 147 devil’s trails: the state of art fig. 13 middle sized ruminant artiodactyl footprints preserved on the surface of the prehistoric pathway: zenital photo (a); depth map (b); contour map � �� � � fig. 14 animal fossil footprints flanking east the trackway b: northern aerial photographic view (a); northern zenital detail photo (b); contour map (0.5 mm) (c); depth map (d). ars who participated to the meeting which took place in the village of tora within the "iv week of the planet earth", under the sponsorship of the italian association of quaternary research (aqua), of the soprintenza archeologia belle arti e paesaggio for the provinces of caserta and benevento and of the municipality of tora and piccilli. although scientists led by paolo mietto (university of padua) have been studying and communicating the risk of permanent loss of fossil footprints for years, no effective plan for the protection and the preservation of this important evidence has been developed by the authorities in charge. this is due to the lack of necessary funding and a bureaucratic maze. the aforementioned research team has, however, conducted a general mapping of the entire site and a high quality 3d modelling of the most important palaeontological details, 148 panarello a. et al. � �� � � in order to preserve at least scientific data and to publish them in the form of a large monographic book about the geosite of the "devil's trails". if, however, the scientific data can be considered already safe, the preservation of the original palaeosurface bearing fossil footprints is still a serious problem, which scholars have, however, presented to scientific and official bodies, providing at the same time a possible solution on which to work. the interventions carried out on the famous laetoli site (agnew & demas, 1996, 1998a, 1998b, 2005; agnew, 2002; bennett et al., 2013) at the south african sites of nahoon point (roberts, 2008, jacobs & roberts, 2009; bennett et al., 2013) and langebaan lagoon (roberts & berger, 1997; roberts, 2008; bennett et al., 2013); and central american cuatro cienegas (gonzalez et al., 2007; lockley et al., 2008; gonzalez et al., 2009; lockley & rodríguez-de la rosa, 2009; morse, 2010; bennett et al., 2013), respectively, showed that the consolidation and/or extraction of parts of the imprinted surface for their preservation inside museums are very risky and unsuitable solutions when other solutions are possible. the isolation and controlled frequentation of icnosites, where possible, seems to be the least risky and the most conservative and applicable solution. a strikingly successful example of this kind of preservation (and promotion) of an ichnosite is the structure created at acahualinca (schmincke et al., 2009, 2010; bennett et al., 2013). if substantially geographical isolation of laetoli site does not make it possible to create and manage a similar structure in that place (dalton, 2008), the extremely favourable position of the "devil's trails" site, which is located close to important communication routes, makes the chance of creating a museum facility able to contain the whole geosite and to effectively control its frequentation not only possible but moreover advisable (panarello, 2016a, 2016b, 2016c). 149 devil’s trails: the state of art fig. 15 a footprint possibly referable to ursichnus europaeus: zenital photo (a); depth map (b); contour map (0.5 mm) (c); southern close -up contoured depth map (1 mm) (d). � �� � � 5. conclusions after extremely thorough analysis and verification of all the evidence, all actual footprints have been separated from the track-like ones. this has been done by applying the most recent and accurate methods (morse et al., 2010; bennett & morse, 2014; panarello, 2016; panarello et al., 2017a; panarello et al., 2017b). a detailed and specific analysis of footprints referable to palaeofauna is underway, both to record specific details of those already known and to identify and to analyse others. this is also in view of a palaeo-environmental and palaeoecological characterization of the general territorial environment in which the "devil's trails" site is located. moss removal from the western part of the trampled tuff slope has also been scheduled, in search of other evidence related to palaeofauna. as already noted, the first palaeoanthropological surveys have already yielded important results and they will be further extended both in the volcanic area and in the surrounding alluvial and carbonate areas, with an increasingly detailed exploration. this survey is expected to provide a decisive aid in specifying the typology and the spread of prehistoric populations throughout the roccamonfina volcano area. a detailed ichnological study of trackway b is in progress with regard also to the presence and relation of fossil prints left by other anatomical parts of the human body. furthermore, as far as permitted by the degree of preservation of the human footprints, some models for the study of locomotion and of other characteristics of the human body of trackmakers are being developed. finally, an ambitious and fascinating project for the preservation, management and international promotion of the entire geosite is going to be completed. it will be submitted to the competent authorities so that it can become a reality and become a museum and a teaching and touristic facility unique in the world, just like the "devil's trails". acknowledgements we thank the two anonymous reviewers for critically reading the manuscript, and warmly acknowledge ms. teresa gray for her kind help in solving all linguistic problems and for her final linguistic revision of the previous version of the manuscript. references agnew n. 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(2007) further research of the willandra lakes fossil footprint site, southeastern australia. journal of human evolution, 52, 6, 711-715. 154 panarello a. et al. ms. received: july 27, 2017 final text received: december 12, 2017 amq abs vallè et al palcom 165-168.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 165 168 testing pollen-climate models over the last 200 years in n-italy using instrumental data francesca vallè 1, michele brunetti 2, roberta pini 3, valter maggi 1, cesare ravazzi 3 1 dept. of environmental and earth sciences, university of milano bicocca, milano, italy 2 institute of atmospheric sciences and climate, cnr, bologna, italy 3 idpa cnr, research group on vegetation, climate and human stratigraphy, laboratory of palynology and palaeoecology, milano, italy corresponding author: f. vallè <francesca.valle@unimib.it> abstract: we evaluated pollen-climate models developed for past temperature reconstruction in northern italy by comparing polleninferred temperature series with site-specific instrumental series in two records covering the last 200 years and provided with a pollen sample resolution of 5/9 years. moderate to good correlation is found. we discuss the methodological approach and the possible influence of human activities in the pollen-inferred reconstructions. keywords: north italy, pollen data, instrumental temperature, pollen-climate models, quantitative summer temperature, last 200 years 1. introduction during the last 50 years, different procedures were developed to quantitatively estimate past environmental and climate variables from stratigraphical microfossil assemblages, including pollen data (brewer et al., 2007, juggins & birks, 2012). the validation of pollen-climate models and the climate reconstructions obtained from palynological data for intervals older than the instrumental data are only possible using statistical tests and procedures (e.g. juggins & birks, 2012 and reference therein). so far, only one paper presented climate reconstructions based on pollen spectra and their validation against instrumental data (st. jacques et al., 2015). no attempts have been done in italy. in this paper we present the first results concerning the development and testing of pollen-climate models to reconstruct summer temperatures over the last 200 years in northern italy. we use two previously published highresolution pollen records, discuss methodological issues and validate the pollen-inferred reconstructions based on the direct comparison with instrumental data obtained for the same sites. 2. materials and methods 2.1 study sites and pollen data the two study sites are located at different altitudes and are characterized by different mean climatological conditions (fig. 1). lago grande di avigliana (353 m a.s.l.) lies at the foothills of the western alps: mean july temperature (reference period 1961-1990) is around 22° c. lago di lavarone (1115 m a.s.l.) is located in the prealpine region: mean july temperature is around 16°c. sediment cores covering part of the late glacial and the whole holocene were extracted from both lakes and studied for their pollen content to reconstruct the vegetation history, also including land-use changes in the two pollen source areas. pollen records covering the last 200 years from lago grande di avigliana and lago di lavarone are presented respectively in finsinger et al. (2006) and in arpenti & filippi (2007). the sequence from lago grande di avigliana has a good chronological control, based on varves counting, 210pb and 137cs dates: mean temporal resolution of the pollen record is fig. 1 map showing the location of the two study sites on t july climatology (1961-1990), adapted from brunetti et al. (2014). lga: lago grande di avigliana (353 m a.s.l.) at the foothills of the western alps and lav: lago di lavarone (1115 m a.s.l.) in the eastern side of the pre-alpine region. https://doi.org/10.26382/aiqua.2018.aiquaconference ~4 years for the last 200 years. a good age control is available also for the lago di lavarone sequence: its pollen record has a mean sample resolution of ~9 years for the last 200 years with higher temporal resolution after ~1900 ad. 2.2 site-specific temperature series for the last 200 years to overcome the lack of representativeness at the local scale of the commonly-used global climatological datasets, monthly instrumental temperature series have been reconstructed for lago grande di avigliana (18332010) and lago di lavarone (1807-2010). series were obtained by means of the anomaly method (new et al., 2000; mitchell & jones, 2005), as described in brunetti et al. (2012), and benefit from the availability of several long instrumental temporal series for northern italy (brunetti et al., 2006). specifically, the procedure consists in the independent reconstruction of the climatological normals over a given reference period (i.e. the climatologies) and the anomalies (i.e. the departures from the climatologies): the former, characterized by remarkable spatial gradients, require a high spatial density of stations (even if with a limited temporal coverage) and a sophisticated interpolation procedure (brunetti et al., 2014; crespi et al., 2018) to be reconstructed. anomalies are more coherent being linked to climate variability and, therefore, a low spatial density is enough but long temporal coverage and accurate homogenization (i.e. the procedure that removes the non-climatic signals introduced by stations and instruments relocation, changes in measurement practices and so on) is mandatory. finally, absolute values of temperature monthly series for each site can be obtained by the superimposition of the two fields. the summer temperature series have been calculated by averaging june, july and august series. in order to highlight the temperature trends and to facilitate the comparison and the correlation between the instrumental records and the pollen-inferred reconstructions, the instrumental summer temperature series were smoothed with loess regression (for lga span=0.05, for lav span=0.1) following the pollen resolution. past statistical software version 3.3 (hammer et al., 2001) was used. 2.3 pollen-based quantitative temperature reconstructions a three-steps approach (juggins and birks, 2012) was applied to obtain quantitative estimates of summer temperature. as a first step we developed an italian modern pollen-climate calibration set that could cover the summer temperature gradients displayed during the last two centuries. 265 modern pollen samples have been selected from the european modern pollen database (empd, davis et al., 2013); each sampling location was associated to site-specific instrumental temperature data, reconstructed for the period 1951-2000 following the same procedure described above. pollen taxonomy has been harmonized, both in the calibration set samples and in the fossil records. the specific training set is the base for the second step, i.e. modeling the modern pollen-temperature relationship and create the 166 fig. 2 a) comparison between instrumental t summer series (grey curves) and the pollen-inferred t summer reconstructions (red dotted curves) obtained for lga and lav with the wa method. the instrumental summer t series were smoothed with loess regression (for lga span=0.05, for lav span=0.1) according to the pollen resolution (black curves). coefficient of determination between the two series are also shown. b) percentages of two anthropogenic pollen taxa, cannabaceae from lga and ostrya from lav, which might influence the pollen-inferred temperature reconstructions. vallè f. et al 167 transfer functions by means of two numerical methods: the weighted-averaging (wa) regression and calibration (ter braak & barendregt, 1986; juggins and birks, 2012 and reference therein) and the weighted-averaging partial least square regression and calibration (wapls) (ter braak & juggins, 1993). we finally applied the transfer functions to fossil pollen records to estimate the summer temperature values for the last 200 years. before applying the transfer functions to the fossil records the statistical performances of the developed models were checked in cross-validation. the goodness of the calibration set in terms of availability of modern analogues for each fossil pollen sample was also evaluated using the modern analogue technique (mat) and its diagnostics. the “real” validation of the pollen-inferred reconstructions has been obtained by comparing the pollen-based temperature series with the instrumental data. the development of wa and wapls models, the evaluation of their performances, the temperature reconstructions and the mat diagnostics were carried out using r software (r core team, 2017) and the rioja, r package (juggins, 2017). 3. results pollen-inferred summer temperature reconstructions obtained for lago grande di avigliana and lago di lavarone are shown together with the instrumental series (fig. 2). wa pollen-inferred summer temperature values obtained for lga are almost constantly underestimated if compared to the instrumental series. they are instead slightly overestimated for lav but, considering the sample specific errors (not shown in fig. 2), they include the instrumental values. despite the shift in the absolute values at lga, the decadal variability and the long-term trend in summer temperature instrumental series are also detectable in the pollen-inferred reconstructions, and this is true for both sites. interestingly, the lga pollen-inferred summer t reconstruction recognizes the warmer interval recorded between 1940 and 1950 ad. the direct comparison of the wa pollen-inferred summer temperatures with the instrumental series yielded a moderate correlation for lga (r2=0.41) and a good correlation for lav (r2=0.7). 4. discussion and conclusion during the last two centuries mean air temperature in italy shows an increasing trend of 1°c per century with an intensification occurred in the last decades (brunetti et al. 2006, 2013). beside this century-long temperature increase, negative trends over shorter periods have been observed at the beginning of the 19th century and between 1950-1970 ad (brunetti et al. 2006, 2013). pollen-inferred summer temperature reconstructions capture the general warming of the last centuries. fig. 2 also presents the pollen percentages of two important pollen-productors which were affected by human land use changes, i.e. cannabaceae from the pollen record of lago grande di avigliana (finsinger et al., 2006) and ostrya from the pollen record of lago di lavarone. cannabis sativa was cultivated in northern piedmont in the 19th century until ~1950 ad (finsinger et al. 2006 and reference therein). whether this taxon is included or not in the pollen sum used for the temperature reconstructions, it influences the reconstructed absolute values. this issue needs to be carefully considered because this pollen taxon is not well represented in the used calibration set. concerning ostrya, this species is today the main component of forest vegetation in the pollen source area of lago di lavarone. its expansion started around 1965 ad, favoured by decreased human activities in the area (arpenti and filippi, 2005). we are aware that wa methods are able to solve the “non-analogues” problems but suffer from the “edge effects” (juggins & birks, 2012 and reference therein). being lago grande di avigliana summer temperature values at the end of the calibration set summer temperature gradient, the constant underestimation of the lga pollen-inferred summer temperature might be due to this reason. this rigid shift in absolute values (which does not affect the long-term variability) is reduced by using wapls model (not shown in fig. 2). our results show that pollen records obtained from lacustrine sediment cores can be used to obtain polleninferred reconstructions with trends comparable to instrumental data over the last 200 years, provided that: 1) pollen records have a robust age control and high sample resolution (ideally less than a decade), 2) proper calibration sets and adequate numerical techniques are used to develop pollen-climate models and transfer functions to be applied to fossil pollen records. the human activities and their effects in the pollen relative abundances must be considered and evaluated in the process of taxa selection before applying quantitative methods. a further perspective after the calibration of pollenbased reconstructions with instrumental data will involve the comparison between the pollen-inferred summer temperature reconstructions and the dendrochronological-based summer temperature reconstructions for common temporal intervals in the alpine region. if the climate signals from both proxies are comparable, those proxies might be combined to build an integrate multiproxy temperature reconstruction for northern italy. acknowledgements this research is funded by the cnr-dta project of interest nextdata, a national system for the retrieval, storage, access and diffusion of environmental and climate data from mountain and marine areas (www.nextdataproject.it). pollen data for lago grande di avigliana were extracted from the european pollen database (epd, http://www.europeanpollendatabase.net/). the work by data contributors and the epd community is gratefully acknowledged. references arpenti e., filippi m.l. (2007) evoluzione della vegetazione nei pressi del lago di lavarone (tn) negli ultimi 2200 anni. studi trent. sci. nat., acta geol., 82, 317-324. pollen-climate models over the last 200 years in n-italy brewer s., guiot j., barboni d. (2007) pollen data as climate proxies. in: elias sa (ed) encyclopedia of quaternary science, (4). elsevier, new york, 24982510. brunetti m., maugeri m., monti f., nanni t. (2006) temperature and precipitation variability in italy in the last two centuries from homogenized instrumental time series. international journal of climatology, 26, 345-381. brunetti m., lentini g., maugeri m., nanni t., simolo c., spinoni j. (2012) projecting north eastern italy temperature and precipitation secular records onto a high resolution grid. physics and chemistry of the earth, 40-41, 9-22. brunetti m., maugeri m., nanni t., simolo c. (2013) variazioni climatiche in italia negli ultimi due secoli. in: il mutamento climatico. processi naturali e intervento umano. bologna, ed. il mulino, pp. 357. brunetti m., maugeri m., nanni t., simolo c., spinoni j. (2014) high-resolution temperature climatology for italy: interpolation method intercomparison. international journal of climatology, 34, 12781296. crespi a., brunetti m., lentini g., maugeri m. (2018) 1961-1990 high-resolution monthly precipitation climatologies for italy. international journal of climatology, 38, 878-895, doi: 10.1002/joc.5217. davis b.a.s., zanon m., collins m., mauri a., bakker j., barboni d., barthelmes a., beaudouin c., birks h.j.b., bjune a.e. et al. (2013) the european modern pollen database (empd) project. vegetation history and archaeobotany, 22, 521-530. finsinger, w., bigler c., krähenbühl u., lotter af., ammann b. (2006) human impacts and eutrophication patterns during the past ~200 years at lago grande di avigliana (n. italy). journal of paleolimnology, 36, 55-67. hammer, ø., harper, d.a.t., ryan, p.d. (2001) past: paleontological statistics software package for education and data analysis. palaeontologia electronica 4(1), 9. juggins s., birks h.j.b. (2012) quantitative environmental reconstructions from biological data. in (birks et al., eds.): tracking environmental change using lake sediments. data handling and numerical techniques. chapter 14, 431-494. springer. juggins s. (2017) rioja: analysis of quaternary science data, r package version (0.9-15.1) (http:// cran.r-project.org/package=rioja). mitchell t.d., jones p.d. (2005) an improved method of constructing a database of monthly climate observations and associated high-resolution grids. international journal of climatology, 25(6), 693712. new m., hulme m., jones p. (2000) representing twentieth-century space-time climate variability. part ii: development of 1901–96 monthly grids of terrestrial surface climate. journal of climate, 13, 2217-2238. r core team (2017) r: a language and environment for statistical computing. r foundation for statistical computing, vienna, austria. url https:// www.r-project.org/. st. jacques j.m., cumming b.f., sauchyn d.j., smol j.p. (2015) the bias and signal attenuation present in conventional pollen-based climate reconstructions as assessed by early climate data from minnesota, usa. plos one 10(1), e0113806. doi:10.1371/journal.pone.0113806. ter braak, c.j.f., barendregt, l.g. (1986) weighted averaging of species indicator values: its efficiency in environmental calibration. mathematical biosciences, 78, 57-72. ter braak c.j.f., juggins s. (1993) weighted averaging partial least squares regression (wa-pls): an improved method for reconstructing environmental variables from species assemblages. hydrobiologia, 269/270, (1), 485-502. 168 vallè f. et al ms. received: may 7, 2018 final text received: may 16, 2018 amq abs principe et al tepro 235-238.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 235 238 geology of monte amiata volcano (southern tuscany) claudia principe 1, luigina vezzoli 1,2, sonia la felice 1 1 igg cnr, istituto di geoscienze e georisorse, pisa, italy 2 dipartimento di scienza e alta tecnologia, università dell’insubria, como, italy corresponding author: c. principe <c.principe@igg.cnr.it> abstract: a multidisciplinary approach, comprising lithological, petrochemical, volcanological, structural, geometric, and morphological analyses on the monte amiata volcanic rocks and their stratigraphic relationships, has been used to reconstruct the evolutionary history of this quaternary volcano, located in the southern tuscany (italy). keywords: monte amiata, quaternary volcano, geological mapping, stratigraphy, volcano-tectonics 1. introduction in this multidisciplinary study, we describe the geological evolution of the monte amiata volcano based on stratigraphic and volcano-geological methodologies into the framework of a robust field-based work. mount amiata is a silicic quaternary volcano located in the southern tuscany (italy). after the first recognition of the volcanic nature of monte amiata made by micheli in 1733 (principe et al. 2017 cum bib), between the end of the 17th and the 19th centuries, there were numerous reports of naturalistic travels carried out in this territory and descriptions of its rocks. modern scientific studies, essentially of petrographic and geographical characters, were carried out from the twentieth century. from the 1950s to 1970s, the volcanology of monte amiata is marked by the ideas of two great names of italian volcanology: alfred rittmann and giorgio marinelli (see principe et al. 2017 cum bib). rittmann introduced the term "rheomorphic ignimbrite" to describe the extensive sheet of glassy volcanic rocks that seem to form a single body at the base of the volcanic edifice. its interpretation is that the large mass of volcanics at the base of monte amiata would be the result of the repeated emplacement of pyroclastic flows emitted by a linear fracture and in their entirety constituting a sheet of rheomorphic ignimbrite erupted from a deep laccolithic structure. marinelli essentially shared this interpretation. the authority of these two scholars made that all the following volcanological studies and geological mapping of monte amiata adopted their volcanological interpretation for the genesis of acidic lavas and the stratigraphic subdivision into three units. this tri-fold division of the volcanic activity of monte amiata includes: (1) a basal trachydacitic complex (btc), in turn divided into a lower unit and an upper unit; (2) a complex of lava domes and flows (dlc), which groups all the domes that make up the summit of the volcano and some lesser lava flows; and (3) the two, basic, lava flows of macinaie and ermeta. in this view, the major volcanological arguments debated on amiata, during the last 55 years, is the occurrence of explosive eruptions and the emplacement of pyroclastic flow deposits during its activity. in particular, the lower unit was considered, into the volcanological and petrochemical literature, as either a unique sheet of ignimbrite and rheoignimbrite deposits, or a sequence of lava flows, or, more recently, the collapse of an endogenous mega-dome. one of the features that previously restricted the distinction of geological units within the volcano was the apparent lithological uniformity that produced the distinction of only two lithological types of rocks and the consequent aggregation of all the outcrops in a few stratigraphic units. the produced review of the scientific literature on the monte amiata volcano (principe et al. 2017 cum bib) has highlighted the gaps and inaccuracies contained in the past interpretations, as well as numerous insights of investigation and discussion that have been a stimulus for the mass of stratigraphic, geological and petrochemical data collected by the research work carried out for the tuscany region project that we summarized in this contribution. actually, although the monte amiata volcano has been the subject of numerous studies, including the production of geological maps at various scales and different details, there was still not a geological model on which to base a reliable reconstruction of its geological structure and volcanological and magmatological evolution. 2. material and methods we performed a detailed field analysis and collected stratigraphic and petrographic data from outcropping deposits and from a continuous deep core drilling named david lazzaretti that was drilled on the southern flank of monte amiata by regione toscana in 2010. this deep coring intersected the entire volcano sequence, comprising volcanic units older than the outcropping rocks, and https://doi.org/10.26382/aiqua.2018.aiquaconference reached the non-volcanic substratum. the stratigraphic analysis has taken into account lithological, petrochemical, volcanological, structural, geometric and morphological characteristics of the volcanic rocks and their stratigraphic relationships. the surficial volcanic units were identified as lithostratigraphic units (more than 30 formations) and grouped into unconformity bounded stratigraphic units (ubsu) with 2 synthem and 5 subsynthem. 3. results the pre-volcanic sedimentary substratum of monte amiata volcano includes the ophiolitic unit and the santa fiora unit of the ligurian domain. the proposed geological evolution comprises two main period of activity that correspond to the older bágnore synthem and the younger monte amiata synthem. they are separated by a major unconformity corresponding to a surface of erosion, saprolithic weathering and tectonic deformation. into the bágnore synthem, there are two subsynthem. the lower, the bagnólo subsynthem, comprises several great lava flows characterized by a vitrophyric perlitic groundmass. they flowed for very long distances (up to 8 km) in all the directions (e.g. sorgente del fiora fm., marroneto fm., piancastagnaio fm., abbadia san salvatore fm., vivo d’orcia fm.). a surface of erosion and unconformity separates the bagnólo subsynthem from the overlying montearioso subsynthem. it is composed of more confined vitrophyric lava flows (e.g. tre case fm., quaranta fm., castel del piano fm.) and one exogenous lava dome and coulée (poggio pinzi fm.). all the rocks belonging to the bágnore synthem show a well-developed weathering that transformed their uppermost portion in a sandy deposit, yellow and reddish in color. the monte amiata synthem comprises three subsynthems. the lower valle gelata subsynthem is characterized by exogenous lava domes with thick coulées (e.g. poggio lombardo fm., pozzaroni fm.) and by long channelized lava flows (e.g. leccio fm., coderino fm.). the intermediate madonna degli scout subsynthem is composed of several exogenous lava domes with short coulées (e.g. poggio della pescina fm., poggio falco fm., corno di bellaria fm., la vetta fm., rifugio cantore fm.), and minor lava flows. all these units are emplaced upon a morphology that has been moulded by tectonic deformations. the final prato della contessa subsynthem comprises several exogenous lava domes (e.g. la montagnola fm., pianello fm.) and lava flows (e.g. ermeta fm., le macinaie fm., cancelle fm, fosso la cocca fm.) from the volcano summit area, and the lateral exogenous lava dome and coulée of the trauzzolo fm. the main tectonic element affecting the monte amiata area is a set of ne-sw-trending faults belonging to the bágnore and bagni san filippo trans-tensional shear zones, located to the south-west and north-east of the volcano, respectively. in addition to these faults, other three sets of lineaments has been recognized on the volcanic area and surrounding sedimentary rocks. they are the older nne-ssw trend, and the ese-wnw and sse-nnw trends that accommodate the stress produced by the ne-sw prevailing trend. all these tectonic regional trends were repeatedly active during the volcano eruptive history. the interaction of these structural elements with the stratigraphic units and the volcanic morphologies, such as domes, coulées and lava flows that compose the monte amiata edifice, hallowed to assess the presence of several volcano-tectonic graben-like structures that formed at different moments of the volcanic history. the older of these grabens corresponds to a depressed area inside the sedimentary substratum under the south-western portion of the volcanic edifice. this first collapse occurred in relationship with the emplacement of the thick succession of domes and lava flows cored by the david lazzaretti drilling. during the subsequent episodes of monte amiata volcanic activity, other grabens formed. these volcanotectonic structures repeatedly interested trachidacitic lava flows and domes, generating nested narrow structural strip on the summit portion of the volcanic edifice. from a couple of these fractures, the less evolved lavas were emitted during, and not at the end, of the volcanic history of monte amiata. the last emitted volcanics are the exogenous domes of la montagnola and poggio trauzzolo formations, unaffected by graben structures. the presence of these volcano-tectonic collapses gives reason of all the structural elements still visible on the volcano and depicts a new interpretation of the monte amiata volcano grown, that is in agreement with morpho -sructural and stratigraphic findings. petrographic analyses allowed us to distinguish five different types of lavas on the basis of textural, structural, and mineralogical characteristics. all these five lava types occur at various stratigraphic positions in all the subsynthems of montearioso, valle gelata, madonna degli scout and prato della contessa, whereas only lavas of one type are present in the bagnòlo subsynthem. all the available whole-rock chemical data of monte amiata volcanics have been reprocessed, considering the stratigraphic position of each sample, and focusing on the quantification of mixing processes between mafic and acid magmas, which were recognized in previous studies. although the chemical composition of meta-sedimentary xenoliths is poorly known, their percentages resulted to be relatively high, from 30 to 45% in lavas and from 35 to 60 % in mafic magmatic inclusions for all the five subsynthems, composing the monte amiata stratigraphy. the proportions of both the mafic end-member in acid lavas and the acid end-member in mafic magmatic inclusions were evaluated getting rid of the contribution of metasedimentary xenoliths to whole-rock chemistry. in this way, it turned out that the mafic end-member in acid lavas attains maximum values of ~15% in the bagnòlo subsynthem, ~17 % in the montearioso and valle gelata subsynthems, ~36 % in the madonna, degli scout subsynthem, and of ~46 % in the prato della contessa subsynthem. the acid end-member in mafic magmatic inclusions reaches maximum values of ~53 % in the montearioso subsynthem, ~34 % in the valle gelata subsynthem (although this figure is affected by the availability of few data), ~57 % in the madonna degli scout subsynthem, and ~64 % in the prato della contessa subsynthem. 236 principe c. et al. 237 fig. 1 schematic reconstruction of the geological evolution of the monte amiata volcano (from principe et al. 2017, pag.98). monte amiata volcano 4. discussion and conclusions the reconstructed succession is indicative of a rapid aggradation of effusive products and does not evidence pyroclastic deposits or mega-breccia facies. the previously undivided, extensive basal unit comprises different, single, superposed silicic bodies, in which we distinguish structural and morphological features typical of lava flows, such as basal and top autoclastic breccia, front ramp structures and surficial ogive structures. both at microscopic and macroscopic scale, the rock texture is not fragmental. individual flow unit does not show evidence of facies variations from proximal near vent (e.g. co-ignimbrite lithic breccia) to distal areas of deposition that is typical of pyroclastic flow deposits. in the individual flow unit, where is not vertical and/or lateral gradation in welding character from nonwelded, to medium grade (with sparse welded zones) to pervasively rheomorphic textures. individual flow units are of small volume and extension, and show channelized lobe geometry. we suggest that the extensive silicic basal (outcropping) unit of amiata volcano is a sequence of lava flows with a rapid aggradation. the stratigraphic framework reconstructed in this work, thanks to the accurate geological field survey, has made it possible to accurately define the nature of the various volcanic bodies (lava flow, lava dome, coulée), according to their lithological and outcrop characteristics, and to place them in their proper position within the geologic evolution of the volcano. as a whole, the volcanic deposits of monte amiata exclusively consisting of a series of acid lava flows, exogenous domes and associated coulées. large volumes of lava blocks, dispersed at the periphery of the volcano, and interpreted in the past as blocky lavas, are related to pervasive surface alterations of pressure ridges on top of the major lava flows and to collapse landslides occurred at the margin of the volcanic body in contact with the shaly deposits of the sedimentary substratum. despite the apparent homogeneity of mineralogical and chemical composition of monte amiata volcanics, invoked in the previous literature as an obstacle to a clear geological and volcanological interpretation of the volcano, we have shown that each identified and mapped stratigraphic unit has petrographic peculiarities that allow its differentiation and recognition, as well as a set of distinguishable lithological and depositional characters. based on the petrochemical data, the preliminary volcanological framework for the bagnólo subsynthem consists of a magma chamber, initially containing a relatively large mass of acid magma, in which a relatively small fraction of mafic magma entered afterwards. during the subsequent periods of volcanic activity, the acid magma batches stationing below the volcano became progressively smaller and the mafic magma venue became consequently more important, originating the abundant mafic magmatic inclusions found in the volcanic deposits. structures and textures of the volcanic deposits suggest the occurrence of complex mingling and mixing processes during volcanic activity. in particular, the mafic magmatic inclusions abundantly present in the volcanic rocks, especially in the most recent units of the stratigraphic sequence, are characterized by the presence of megacrysts in chemical disequilibrium, that are also consistent with the occurrence of mingling processes. acknowledgements this work derives from a research project on the monte amiata volcano funded by the regione toscana, sistema informativo territoriale ed ambientale branch. references marinelli g. (1961)genersi e classificazione delle vulcaniti recenti toscane. atti soc. tosc. sc. nat., serie a, lxviii, pisa. micheli p. a. (1733) manoscritto citato in lotti b. (1932) appunti fisiografici sul monte amiata. memorie soc. geol., it. 1-8. principe c., lavorini g., vezzoli m.l. (eds) (2017) il vulcano di monte amiata. eds nola, pp.400, isbn 978-88-99742-32-4, pp.399. rittmann a. (1958) cenni sulle colate di ignimbriti. boll. acc. gioenia sc. nat. serie iv, 10, catania. 238 principe c. et al. ms. received: may 3, 2018 final text received: may 21, 2018 available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 59 62 quaternary urban geology and foundations of heritage buildings: a few outstanding case histories from italy massimo coli, niccolò iandelli dst dipartimento di scienze della terra, università degli studi di firenze, firenze, italy corresponding author m. coli <massimo.coli@unifi.it> abstract: in this paper we analyse the urban geological setting of three outstanding italian cities, under the unesco patronage, in order to define the relationships between subsoil setting and historical building foundations. geological features play a key role on this topic and their knowledge is fundamental for any conservation project. keywords: urban geology, holocene, cultural heritage, building, foundations 1. introduction most of the main historical cities has been settled in plain areas, close to a river or to the sea, on quaternary deposits. in these areas, the ground is often constituted by recent unconsolidated, cohesive and granular, alluvial or paralic deposits, more or less thick and with complex sedimentary and lithological assemblages and with hiatus and heteropies. during time geological hazards like floods, subsidence and earthquakes, can severely damage or even destroy heritage buildings. in this context, urban geology, devoted to the study of the recent geological aspects, underground geological setting and geotechnical properties, plays the main role due to its great influence on the foundation, ensuring stability and durability of the heritage buildings. in this paper, we outline the role played by the urban geology for a few selected italian outstanding cities in the foundations behaviour of their main heritage buildings. namely we analyse the case histories of firenze city centre, venezia and pisa; they all are unesco human cultural heritage sites. 2. case histories 2.1. firenze firenze was settled by the romans in the ii century b.c. in a natural territory with swamps, marshlands and a river with a large bed within which it flew with braided channels. first the romans reclaimed the plain for agriculture through the centuriazione, whose imprinting is still deeply marking the territory as cadastral parcels and ditches and drains. during its history firenze has been expanding, reclaiming the flood territory all around. the firenze-pistoia basin has been developing since the piacenzian, dismantling the zanclean low energy surface; this recent geological evolution, according to the allostratigraphy criteria, resulted into continental clastic deposits grouping into three ubsu (briganti et al., 2003, coli & rubellini, 2013) including: synthem of the basin: lacustrine, alluvial and fan deposits; piacenzian-gelasian. ancient deposits: river-bed gravel of the paleo-arno; late pleistocene. recent deposits: river-bed and alluvial deposits of the arno river and tributaries, with swamps and marshlands in the plain; holocene. in the historical city centre area, the recent deposits of the alluvial bed of the arno river directly lie on the bedrock; here, below a few meters of archaeological layer, the recent deposits are constituted at top by around 2 m of over-bank sands and silty-sands and below by river-bed deposits mainly made of pebbles and gravels, from clean to silty, with layers and lenses of locally graded sands; they are referred to a fluvial subaerial environment where the arno river braided unconstrained in its alluvial bed, but periodically flooded large portions of the plain. in the city centre there are two sites of main interest: the religious complex of the cathedral with the brunelleschi’s dome, the baptistery and the giotto’s bell tower, and the civil complex of palazzo vecchio and uffizi gallery; here the subsoil sequence is (fig. 1): historical archaeological layer (v-xii century a.d.), about 3-4 m thick, corresponding to roman and early medieval buildings ruins and debris. about 2 m of silty-sand of banks and overs-banks. about 12 m of river bed gravel. bedrock, at around 17 m depth below the street datum in the cathedral area and around 10-12 depth below the street datum in the palazzo vecchio area. the recent deposits of the firenze area display good geotechnical properties, gravels fall into the gw/gp fields of the uscs (astm 1988) and sands into the sp/ sw fields. sands and gravel have vs = 120 m/s and vs = 400 m/s, respectively. gravels are most calcareous, dense and self-sustaining, with = 37°+/6°, as statistically deriving from 203 nspt data from the whole city centre area. the archaeological debris have nspt data ranging from 5 to 7. the water table is stable at about 7 m below the ground datum, with a seasonal excursion of about +/1.5 m and in equilibrium with the arno river, https://doi.org/10.26382/aiqua.2018.aiquaconference which in turn is kept on level by a barrage downstream the historical city. the foundation of the main historical buildings of firenze date back to the xiii century and is constituted by massive bodies of mortared stones, with a high quality mortar. they are 6 m depth and rooted into the gravels, right above the water table. 2.2 venezia venezia is located in a complex foreland setting near the pinch-out of both the south alpine and the apenninic wedges, which developed during serravallianmessinian ad early pliocene times, respectively. the present-day venezia area was reached by the northadriatic turbidite system during the early to middle pleistocene, due to the north-eastward shifting of the apenninic fore-deep (bassan and vitturi 2003). the holocene-pleistocene transition is marked by the caranto, which is an over-consolidated layer of sand and clay mixture considered to be the last continental unit before the holocene (flandrian) transgression, that progressively submerged the “würmian” palaeoplain and the caranto itself, here interpreted like a hardground (bonardi & tosi, 1994). the early holocene sediments are represented by a discontinuous level of silt and sand, often with chaotic structure mixed with shelly marine-lagoon sands due to the sediment redistribution operating by the sea currents on the clasts supplied by the rivers descending by the alps. venezia is placed on the recent lagoon deposits, the water table is at the sea level about 1÷1.5 m below the streets datum and therefore all the sediments are saturated. during the quaternary, the lagoon underwent some discontinuous phases of alternating marine transgressions and regressions, as a result of which both marine and continental sediments coexist (fig. 2) (zezza, 2008 cum bib). both recent lagoon and fluvial pleistocene soils display bad geotechnical features: for cohesive layers cu values range between 5°÷35°; vs values are around 265 m/s. cohesive layers display very high compressive and plasticity indexes, only the caranto layer, has a certain grade of stiffness. the lagoon deposits present a typical soil profile characterized by the presence of the following type of sediments, according to uscs (astm 1988): 35% sands (sp, sm), 35% silts (ml), 25% clays, (cl), 5% soils with relevant organic matter (mh, oh, pt). therefore, both cohesive and granular soils are subject to compaction due both to natural factors and to 60 coli m., iandelli n. fig. 1 schematic subsoil setting of the main historical buildings at firenze. fig. 2 subsoil geological setting of venezia along a cross-section (after zezza 2008). 61 the load of the city buildings. in the city area that resulted into a subsidence rate of around 0.6 mm/y, with subsidence differentiated through the city according to the local subsoils setting. in venezia buildings foundations consist of a complex system based on the interaction of wood, water and soil. because surficial soils have a low lift capacity, ancient builders used wooden poles in order to improve the geotechnical properties of the first layers and transfer the load to the below caranto layer where poles had been rooted. this type of foundation is called "indirect foundation" (biscontin et al., 2011). 2.3 pisa pisa was settled by the etruscans in the vii century b.c. on the coastal plain, at the confluence of auser (ancient serchio) and arno rivers, close to the coast as a harbour. later on, the sediments supplied by the arno and serchio rivers and beach sand cordons moved the coast west away from pisa. the pisa plain is the top of an inner inter-montane basin developed since late tortonian, which development had been controlled by normal faults on the eastern side. above messinian to pleistocene deposits, the recent holocene deposits consists of fluvial and paralic clastic sediments supplied by the incoming rivers, most the arno and the auser rivers. in particular, the city of pisa lies above a deep paleo-valley eroded by arno river during the last lowstanding of the “würm ice-age” into pleistocene and pliocene marine deposits. later on, the paleo-valley was infilled by down-lap arno river fluvial sediments from east and on-lap marine sediments from west, in a complex relationship of paralic environments: estuary, lagoon, coastal plain, bay-head delta, floodplain, fluvial channel; these recent infilling and the top sediments are mainly constituted by sands and clays (fig. 3) (aguzzi et al., 2005, 2007; amorosi et al., 2008; sarti et al., 2015). the soil of the pisa area presents a certain grade of over-consolidation that had been mainly attributed to the effects of ageing and, to a minor extent, to mechanical over-consolidation, due to erosion-re-deposition processes and water table fluctuation; all are soft soils with bad geotechnical properties. the leaning tower has ring-like shallow foundation, rooted up to 2 m below the ground datum, right above the water table (mlp 1971). walls and foundations were made in wall-bag mode, with mortar of no very good quality; in the year 1935 the foundations were reinforced by grouting and with a concrete outer ring. under the overburden of the tower, subsoil has been undergoing progressive viscousplastic deformation, which resulted into a vertical settlement of 2.5 m and symmetric rotation of the tower, the leaning rate before the recent conservation works was of around 1.5 mm/y. this natural process had been helped by the pumping out water, since the 1950’s, with subsidence of the whole pisa plane. in order to stop/ reduce the increasing leaning of the tower which was becoming critic, in the 1965 the ministry established a urban geology and historical buildings foundation fig. 3 subsoil setting of the pisa area evidencing arno paleo-valley during the last “ice-age” (after amorosi et al. 2008). national scientific committee (nsc) that proceed to soil sub-excavation below the upright side of the tower; the works were executed in the year 2000-2001 by means of 41 drill-holes. these works allowed to achieve a gain of 0.5° of back-rotation and to put on safety the tower for the close future. 3. remarks when we have to address a problem of conservation for ancient historical buildings first of all we must acquire a historical and technical full knowledge of the monument, and of its detailed geological and subsoil setting, foundations and materials and original building techniques. only after we have achieved these goals we can design conservation interventions in the full respect of the monument authenticity and integrity. the interventions must be carried out with the in-depth knowledge of the geological and depositional characteristics, and with knowledge of the stratigraphic sequences, the geological model and the type of depositional events in the period that goes from the last glaciation to now. references aguzzi m., amorosi a., sarti g. (2005) stratigraphic architecture of late quaternary deposits in the lower arno plain (tuscany, italy). geologica romana, 38, 1-10. aguzzi m., amorosi a., colalongo m.l., lucchi m.r., rossi v., sarti g., vaiani s.c. (2007) late quaternary climatic evolution of the arno coastal plain (western tuscany, italy) from subsurface data. sedimentary geology, 202(1), 211-229. amorosi a., sarti g., rossi v., fontana v. (2008) anatomy and sequence stratigraphy of the late quaternary arno valley fill (tuscany, italy). geoacta, special pubbl. 1, 55-66. astm (1988) d2487-11 standard practice for classification of soils for engineering purposes (unified soil classification system). american society for testing and materials, http://www.astm.org/. bassan v., vitturi a. (2003) studio geoambientale del territorio provinciale di venezia. parte centrale. provincia di venezia-sigea, serv. graf. ed., padova, pp. 112. briganti r., ciufegni s., coli m., polimeni s., pranzini g. (2003) underground firenze: plio-quaternary evolution of the firenze area. boll. soc. geol. it., 122, 435-445. bonardi m., tosi l. (1994) the holocene-pleistocene boundary zone in the lagoon of venice – in: marabini f. editor, italian contribution to the china-italy bilateral seminar on marine geology, (4-6 october 1994, qingdao, china). istituto di geologia marina, cnr, bologna, tech. rep. 40, 18-24. biscontin g., izzo f.c., bini c., rinaldi e., macchioni n., pizzo b., capretti c., molon g., regini m., lionello a., cavaggioni i., morabito z. (2011) wooden foundations in venice: a preliminary study. schipwrecks 2011 chemistry and preservation of waterlogged wooden shipwrecks, stockholm, royal institute of technology, convegno, 18-21 ottobre 2011. coli m., rubellini p. (2013) geological anamnesis of the firenze area, italy. z. dt. ges. geowiss. (german j. geosci.), schweizerbart’sche verlagsbuchhandlung, stuttgart, germany, 581-589. mlp (1971) ricerche e studi su la torre pendente di pisa e i fenomeni connessi alle condizioni d’ambiente. ministero lavori pubblici, commissione per il consolidamento della torre di pisa. igm, firenze, 3. sarti g., rossi v., giacomelli s. (2015) the upper pleistocene “isola di coltano sands” (arno coastal plain, tuscany italy): review of stratigraphic data and tectonic implications for the southern margin of the viareggio basin. atti soc. tosc. scie. nat. mem., serie a, 122, 75-84. zezza f. (2008) geologia: proprietà e deformazione dei terreni del centro storico di venezia. geologia dell’ambiente, sigea, 3/2008, 129-170. 62 coli m., iandelli n. ms. received: april 30, 2018 final text received: may 28, 2018 http://www.astm.org/ available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 73 78 now or never: the study of disappearing ice archives in the time of global warming daniela festi free university of bozen-bolzano, faculty of science and technology, bolzano, italy university of innsbruck, department of botany, innsbruck, austria corresponding author: d. festi <daniela.festi@uibk.ac.at> abstract: mountain glaciers in the alps can provide detailed information on past climatic conditions. regrettably, their persistence is currently threatened by the ongoing warming. this situation generates public concern and the need to recover and preserve ice cores before their stratigraphy is permanently compromised. this contribution reports on recent ice core drillings in the eastern alps implementing new approaches to directly link the climatic signal retained in the ice with the palaeo-environmental component of the ice. keywords: pollen, environmental dna, mountain glacier, cryopalynology, ice cave, timescale 1. introduction since the first signs of global warming have been recognised, the scientific community committed to provide evidence of past and current climate change, as well as an understanding of its causes, to support policymakers and governments in their decisions. in the frame of these investigations, it has been recognised that the warming is particularly severe in the european alps, where temperature is rising at twice the global rate (ipcc 2013). the rapid retreat of alpine glaciers is probably the most striking evidence of the drastic effects of the ongoing climate warming. recent estimations speculate that european glaciers experienced a loss in ice volume of 49% in the period 1900-2011 (huss, 2012). their retreat has a considerable impact on both the scientific community and the public, as it can be witnessed on a timescale as small as a lifetime (diolaiuti et al., 2012). this situation clearly generates public and scientific concern, creating an urgent need for detailed investigation of glacier content, before the ice bodies become permanently compromised. it is, indeed, a “now or never’’ situation, as the increased summer ablation, leading to progressive percolation, is already compromising the integrity of glaciers as palaeo-archives. furthermore, while the vanishing of the surface cryosphere is evident, the decline of the underground cryosphere is less striking, yet equally concerning. ice masses hosted in caves have a great potential for palaeo-environmental studies (e.g. luetscher et al., 2005), providing complementary information to mountain glaciers, as they occur at lower altitudes and generally, where surface glaciation is altogether missing (kern & perşoiu 2013). in the past decades, main efforts of ice cores studies in the alps converged on the western part of the mountain range (i.e. monte bianco and monte rosa massifs, icb, http://geomatic.disat.unimib.it), because of their higher elevation, which let presume the possibility of retrieving intact ice records. in the eastern alps little research has been done (i.e. vernagtferner, von gunten et al., 1982). finally, the approach used to study glacier ice cores considerably resembled that developed for polar ice caps, which was established to obtain quantitative palaeo-climatic reconstructions. this practice has given little attention to the biological proxies present in the ice, e.g. pollen (vareschi, 1934; bortenschlager 1970) and left highly unexplored the possibility of directly linking climatic and environmental evidence enclosed in glaciers. this gap has finally been recognised by both ice core scientists and palaeo-ecologists, who began developing new approaches, to exploit glacier ice in a more comprehensive way, including well established palaeo-environmental proxies, e.g. pollen, as well as new generation proxies, e.g. environmental dna (edna). the present contribution, based on published data and personal engagement in ongoing research projects, reports on: i) filling the gaps in ice core studies in the eastern italian alps; ii) recent advances in pollen as a chronological tool for ice core; iii) the potential of mountain glaciers as palaeo-environmental archives. 2. methods 2.1. filling the gaps in the eastern alps choosing the ideal site is the key of success of every palaeo-climatic and palaeo-ecological study. in a period of climate warming this proves to be a challenging task, especially for ice core drilling in the eastern alps, where glaciers are found at lower elevation. here two drilling sites are presented. the alto dell’ortles glacier is the highest glacier in the eastern alps, with an altitude ranging from 30183905 m a.s.l. the ice body is located close to the border between italy, austria and switzerland (figure 1), on the north-western slope of the mt. ortles, and covers an area of about 1.04 km 2 (gabrielli et al., 2012). the features making alto dell’ortles a suitable site for ice core studies in the eastern alps are: i) its high altitude setting; ii) the great thickness of the ice, ca. 75 m; iii) the presence of cold ice (gabrielli et al., 2012); iv) an excellent lamination of the exposed ice layers down to bedrock observed prior to drilling (gabrielli and others, 2010). finally, the glacier is also a good candidate for successful cryopalyhttps://doi.org/10.26382/aiqua.2018.aiquaconference nological analyses, due to the vicinity of the vegetation and the efficient uplift by thermic winds that ensures an effective transport of pollen from the surrounding area. project ortles aims at studying the glacier as an indicator of past and current climate change, and includes the study of pollen, isotopes, major ions, trace elements and levoglucosan as determined in ice cores, as well as the investigation of the glacier physical features and the surrounding permafrost areas. the goal of palynological analysis is to provide a pollen-based timescale of the cores, as well as to explore the potential of pollen analyses in ice core for palaeovegetational and palaeoclimatic reconstructions. the pian di neve glacier covers an 8 km² large plateau located in the adamello massif at an altitude of 3100-3400 m a.s.l. (figure 1). with its ~270 m of depth, it is the deepest italian glacier and, together with the adjacent mandrone glacier, it is also the largest glacier of italy (picotti et al., 2017). pian di neve was chosen as a drilling site for its suitability to study the interactions between climate, biosphere and human activities because of: i) the expected high time resolution due to the mighty ice thickness; ii) the vicinity of vegetation, due to its low altitude, which ensures an input of biological proxies; iii) its vicinity to the high industrialised po plain, which provides a long record of anthropic activity. 2.2. advances in pollen as a chronological tool the classical interpretation of pollen diagrams to detect annual variation in the pollen spectra is not very handy when dealing with thousands of samples, as it is often the case in the analyses of deep ice cores. thus, novel approaches were developed to condense the complex palynological information of the core, and to provide a precise timescale. both methods, hereafter summarised, were developed and tested on a 10 m (459 cm w.e. water equivalent) shallow core retrieved on the alto dell’ortles glacier. the first approach developed by festi et al. (2015) is based on the extraction of the seasonal signal by principal components analysis (pca) of pollen assemblages obtained by high level taxonomical identification (details in festi et al., 2015). this approach allows to extract seasonal components indicative of the original flowering seasons and easily visualise the succession of different seasons (spring, early and late summer) along the core (figure 2 a). the second method is based on a “space-fortime” (or “depth-to-day” substitution) by pollen content of ice samples (depth) and daily pollen monitoring samples (day) of a nearby aerobiological station. by coupling the pollen content of firn/ice samples with the most statistically similar pollen assemblage of the airborne samples, a link can be established between pollen deposition at a specific sample depth on the glacier and a specific day of the year (doy) of the daily monitoring (details on the method in festi et al., 2017). 2.3. ice cores as palaeoenvironmental archives the pian di neve ice core was specifically recovered to obtain environmental information from the ice. calicecalibrating biodiversity in glacier iceis in fact the first ice core project mainly targeting the biological component of the glacier. pollen and plant edna analyses are conducted in order to reconstruct changes in biodiversity during the last 70 years, in relation with climate warming and human impact (changes in land use and practices, industrialisation, etc.). these results will be validated by biodiversity estimates from the region, obtained with remote sensing, historical archives and field surveys. this approach will generate the very first plant diversity record obtained by pollen and dna analyses from an alpine ice core, validated by historical biodiversity assessments. this approach significantly contributes towards the possible exploitation of mountain glaciers as palaeo-ecological archives. however, every palaeo-ecological reconstruction should be established on a deep knowledge on how the proxies are incorporated and build up the signal object of analyses. such processes are poorly investigated for pollen and dna in glaciers. to fill this gap, direct and indirect approaches are possible: i) on site pollen/dna monitoring; ii) combining pollen analyses from ice samples with mass balance modelling. the first approach is currently implemented near the drilling site of pian di neve, where a daily pollen monitoring station has been set up. this data will provide important information on the variations in time of the pollen load transported by the air masses over the glacier, in terms of both quantity and pollen types. this pattern is presumably reflected by changes in pollen spectra and pollen concentration found in the ice. the second and indirect approach was already tested on the alto dell’ortles shallow core (festi et el., 2017) by combining palynological results with the results of mass balance modelling for the drilling site (eismodel, carturan et al., 2012). the mass balance model simulates accumulation and melt processes at hourly time steps. for each snow layer deposited (i.e. the water equivalent that accumulates at the surface of the snowpack during an hourly time step), the model provides its time and date of formation, as well as the air temperature during its deposition (figure 3). for details on eismodel refer to carturan et al. (2012). 74 festi d. fig. 1 map of northern italy showing the location of ice core drilling sites presented: [1] alto dell’ortles glacier; [2] pian di neve glacier, adamello massif. 75 3. results 3.1. filling the gaps in the eastern alps drilling expeditions on both the alto dell’ortles and pian di neve glaciers were successful despite the technical challenges associated with coring temperate glaciers, and a climatic and environmental signal was retained in the ice of both ice bodies. in the frame of the project ortles two coring expeditions led by project leader paolo gabrielli (ohio state university) were conducted. in 2009 a firn core of 10 m (459 cm w.e.) was retrieved, while in 2011 four deep cores of about 75 m (~60 m w.e.) were extracted. the dating of the deep ice cores based on 210pb, tritium, beta activity and 14c analyses, provided a maximum age of the bottom layers of ∼7 ka, during which it is presumed that the drilling site was continuously glaciated on frozen bedrock (gabrielli et al., 2016). pollen analyses have been performed on the short core at 10 cm resolution on 103 samples, and on one of the deep cores (c1) at 10 to 3 cm resolution, leading to ca. 1840 samples. pollen concentration on the long core varied from 0 to 27 grains/ml and about 120 pollen and spore types were identified. the palynological data showed that an annual signal was retained in most of the core. the complete pollen-based timescale is currently being combined with the results of isotopes and dust analyses to accomplish a final multi proxy annual timescale. pian di neve. in the frame of calicecalibrating biodiversity in glacier ice a 42 m core has been retrieved in april 2016 from the centre of the glacier by a drillers team lead by valter maggi (milano bicocca university). first results of pollen analyses on 200 ice samples show a pollen concentration from 0 to about 35 grains/ml. 3.2. advances in pollen as a chronological tool both statistical methods were tested on the alto dell’ortles short core. the pollen content of firn samples (~30ml each) was very variable, and concentration values range from 0 to 47 grains/ml. pollen grains were mostly characterised by an excellent state of preserva the study of ice archives fig. 2 (a) alto dell’ortles firn core 2009 timescale (festi et al., 2015) based on principal component analyses. as every principal component (pc) condenses the seasonal information of the pollen spectrum, scores values should be interpreted as follows: a sample (w.e. depth down) presenting high component scores values for a specific pc is characterised by a pollen content reflecting predominantly the season corresponding to that particular pc. (b) mean date (day of the year ± 1 sigma) obtained by using the depth-to-day method (festi et al., 2017); empty squares represent inversions (c) pollen concentration in the alto dell’ortles 2009 firn core. (d) number and mean thickness (colour scale) of ice lenses per sample (figure from festi et al., 2017). tion, and their identification led to a pollen spectrum of 64 pollen types (for details refer to festi et al., 2015). the seasonal variations reconstructed with both methods are shown in figure 2, together with changes in the concentration of pollen and spores. both methods led to the conclusion that the core includes five years of snow accumulation (2005-2009) and highlight a substantial difference in the pollen distribution patterns in the snow, both within and among flowering seasons. flowering seasons stood out distinctively as layers with high pollen concentration, variable inter-annual thickness and seasonality patterns. according to their thickness and vertical distribution of pollen, the flowering years clustered in two groups: 2005 and 2006 vs. 2007, 2008 and 2009. specifically, the flowering seasons of 2007 and 2008 corresponded to very thick firn layers, into which pollen was distributed with a clear seasonal pattern. in contrast, the flowering seasons of 2005 and 2006 were characterised by a lower firn thickness, the occurrence of a thin lower layer with a distinct spring pollen content, and a thin upper layer containing mixed spring/summer pollen. on the contrary, the “winters” (october to february) were clearly visible as firn layers of different thickness, which are free (or nearly free) of pollen. winter 2007/08 was the thinnest with only 33 cm w.e., followed by 2006/07, 2005/06, and finally 2008/09 with 91 cm w.e. this method allows very precise dating of the time of deposition of snow samples according to their pollen content. ortles deep core. pollen concentration varied from zero to 27 grains/ml and about 120 pollen and spore types were identified. the data show that an annual signal was clearly retained in most the core. the annual timescale is currently under construction by combining the results of pollen, isotopes and dust analyses to refine the depth age model by gabrielli et al. (2016). pian di neve. first results of pollen analyses on 200 ice samples indicate that an annual signal is preserved in the deeper strata of the core. 3.3 ice cores as palaeoenvironmental archives preliminary results of pollen analyses of the pian di neve core indicate a fairly rich palynological diversity, which combined with the ongoing edna analyses will provide a good record of past plant diversity. the pollen spectra were characterised by ca. 80 pollen and spore types, reflecting alpine, subalpine, montane and mediterranean vegetation types. pollen grains of crops (e.g. secale cereale, zea mays) as well as cultivated trees (castanea sativa, juglans regia, olea europaea) and neophytes (ambrosia sp., eucalyptus sp.) also occurred in the analysed samples. diatoms, fungi spores and butterfly scales were among the non-pollenpalynomorphs found in the samples. this supports the hypothesis that analyses of biological proxies on glaciers can generate useful palaeo-environmental record. with respect to the advances in process understanding of the formation of the pollen signal in the ice, comparison between pollen-based timescale and mass balance modelling revealed the great potential of pollen for inferring past climatic conditions at a sub-seasonal resolution in ice core records. based on the pollen content in the alto dell’ortles strata of the shallow core (figure 2), three main types of pollen assemblages could be identified and correlated with the corresponding climatic conditions inferred for by the model for that season: i) thin pollen-rich layers with fairly clear date order but overlapping of principal components (i.e. 2005 and 2006, figure 2). according to the modelling, such layers were the result of intense summer ablation, thus pointing to warm and dry summer conditions; ii) thick layers with substantial pollen concentration and welldistinguished succession of dates (i.e. 2007 and 2008). for these layers the model showed a spring/summer snow deposition generated by copious precipitation and low temperatures, and characterised by negligible melting; iii) thick pollen free layers, reflecting autumn and winter snow deposition. figure 3 shows the comparison of the mass balance reconstructed according to the pollen-based timescale with those by the mass balance model eismodel (festi et al. 2017). remarkably, these are the first results pointing to the potential of pollen to reconstruct not only past vegetation, but also climate conditions and snow deposition patterns. this approach also suggests a high resilience of pollen grains to water percolation, as they seem to persist on the surface of ablation layers. 4. discussion and conclusion the success of the drillings expeditions and ice core analyses on alto dell’ortles and pian di neve glaciers demonstrate that ice bodies in the eastern alps are 76 festi d. fig. 3 comparison of the winter and summer mass balance as obtained by pollen dating and modelling (eismodel). capable of retaining information on past climate, environment and human activities. the date of 7 ka, obtained for the basal ice of the alto dell’ortles, points to the possible presence of ice older than the little ice age, preserved in the deeper parts of the glaciers. in particular, the idea of dating the deepest layers of pian di neve (270 m) is certainly tempting and might lead to unexpected results. the recent advances in pollen-based chronology for ice core prove that accurate analyses can provide reliable annual to sub-seasonal timescales. such studies also indicate that pollen grains are not affected by water percolation like other proxies in the ice (e.g. stable isotopes) and therefore tend to accumulate on the ablation surfaces. future challenges beyond the presented projects include: i) finding new suitable sites for ice core drilling on the alps; ii) recovering endangered ice archives; ii) conserving the ice for future studies; iii) establishing a standard approach including environmental and climatic proxies; iv) expanding the range of investigated ice archives to ice caves as a valid complementary palaeoarchive. the scientific community has already begun to partially address these issues. garzonio et al. (2018) has made the first step towards the development of a methodology to assess the suitability of alpine glaciers for ice core drillings, in order to facilitate the collection of cores with a preserved stratigraphy, while the “protecting ice memory” project has started recovering ice cores from mountain glaciers most at risk (in the alps and the world), and storing them in antarctica for future generations of scientists. finally, the study of ice masses from caves is becoming increasingly important as their suitability for palaeo studies has been recognised. preliminary palynological studies on such ice archives are ongoing in at least two caves located in the eastern alps in the frame of project c3cave’s cryosphere and climate (https:// www.c3project.net) and at the cenote cave (santagata et al., 2017). acknowledgements the author would like to thank all members of the project ortles, calice and pollice consortia, the euregio science fund for financial support to calicecalibrating biodiversity in glacier ice, and the autonome provinz bozen-südtirol, abteilung bildungsförderung, universität und forschung for financial support to the project pamogis (pollen analyses of the mt.ortles ice samples). this is ortles project publication n. 9 and calice publication n 1. references anzidei a.p., bulgarelli g.m., catalano p., cerilli e., gallotti r., lemorini c., milli s., palombo m.r., pantano w., santucci e. (2012) ongoing research at the late middle pleistocene site of la polledrara di cecanibbio (central italy), with emphasis on human-elephant relationships. quaternary international, 255, 171-187. bortenschlager s. (1970) probleme und ergebnisse der untersuchung von pollenspektren im hochgebirge (kesselwandferner, ötztaler alpen, 3240 m). mitteilungen der ostalpin-dinarischen sektion der internationalen vereinigung für vegetationskunde, 10(2), 5-9. carturan l., cazorzi f., dalla fontana g. (2012) distributed mass-balance modelling on two neighboring glaciers in ortles-cevedale, italy, from 2004 to 2009, journal of glaciology, 58, 467-486. diolaiuti g., bocchiola d., d’agata c. smiraglia c. (2012) evidence of climate change impact upn glaciers within the italian alps. theor appl climatol, 109, 429. festi d., carturan l., kofler w., dalla fontana g., de blasi f., cazorzi f., bucher e., mayr v., gabrielli p., oeggl o. (2017) linking pollen deposition and snow accumulation on the alto dell’ortles glacier (south tyrol, italy) for sub-seasonal dating of a firn temperate core. the cryosphere, 11, 93748. festi d., kofler w., buch-er e., carturan l., mair v., gabrielli p., oeggl k. (2015) a novel pollenbased method to detect seasonality in ice cores: a case study from the ortles glacier, south tyrol, italy. journal of glaciology, 61(229), 815-824. gabrielli p., barbante c., bertagna g., bertó m., binder d., carton a., carturan l., cazorzi f., cozzi g., dalla fontana g., davis m., de blasi f., dinale r., dragà g., dreossi g., festi d., frezzotti m., gabrieli j., galos s., ginot p., heidenwolf p., jenk t. m., kehrwald n., kenny d., magand o., mair v., mikhalenko v., lin p. n., oeggl k., piffer g., rinaldi m., schotterer u., schwikowski m., seppi r., spolaor a., stenni b., tonidandel d., uglietti c., zagorodnov v., zanoner t., zennaro p. (2016) age of the mt. ortles ice cores, the tyrolean iceman and glaciation of the highest summit of south tyrol since the northern hemisphere climatic optimum, the cryosphere, 10, 2779-2797. gabrielli p., barbante c., carturan l., cozzi g., dalla fontana g., dinale r., draga g., gabrieli j., kehrwald n., mair v., mikhalenko v.n., piffer g., rinaldi m., seppi r., spolaor a., thompson l.g., tonidandel d. (2012) discovery of cold ice in a new drilling site in the eastern european alps. geografia fisica e dinamica quaternaria, 35, 101105. gabrielli p., carturan l., gabrieli j., dinale r., krainer k., hausmann h., davis m., zagorodnov v., seppi r. and barbante c. (2010) atmospheric warming threatens the untapped glacial archive of ortles mountain, south tyrol. journal of glaciology, 56 (199), 843-853. garzonio r., di mauro b., strigaro d., rossini m., colombo r., de amicis m., maggi v. (2018) mapping the suitability for ice-core drilling of glaciers in the european alps and the asian high mountains. journal of glaciology, 64 (243), 12-26. huss m. (2012) extrapolating glacier mass balance to the mountain-range scale: the european alps 1900-2100, the cryosphere, 6, 713-727. kern z., perşoiu a. (2013) cave ice the imminent 77 the study of ice archives https://www.c3project.net loss of untapped mid-latitude cryospheric palaeoenvironmental archives. quaternary science reviews, 67, 1-7. ippc (2013) climate change 2013: the physical science basis. contribution of working group i to the fifth assessment report of the intergovernamental panel on climate change. stocker t.f. et al eds. cambridge university press, cambridge, uk and new york, usa, pp. 1535. luetscher m., jeannin p., haeberli w. (2005) ice caves as an indicator of winter climate evolution: a case study from the jura mountains. the holocene, 15, 982-993. picotti s., francese r., giorgi m., pettenati f., carcione j. m. (2017) estimation of glaciers thickness and basal properties using the horizontal to vertical spectral ration (hvsr) technique from passive seismic data. journal of glaciology, 63 (238), 229248. santagata t., sauro f., spötl c., festi d., oeggl k., dal molin l., kadded f., camorani m., romeo a. (2017) the cenote project: monitoring a highaltitude ice cave in the dolomites, italy. proceedings of the 17th international congress of speleology, 86-88. vareschi, v. (1934) pollenanalysen aus gletschereis. ber. geobot. inst. rübel, 81-99. von gunten h. r., rössler e., gäggeler h. (1982) dating of ice cores from vernagtferner (austria) with fission products and lead-210. zeitschrift fuer gletscherkunde und glazialgeologie, 1, 37-45. 78 ms. received: may 17, 2018 final text received: may 22, 2018 festi d. amq abs giustini et al palcom 135-139 corr.pub available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 135 139 an introduction to the early holocene “eolian” deposits of grotta romanelli, apulia, southern italy francesca giustini 1, fabio bona 4, mauro brilli 1, jacopo conti 2, alessia d’agostino 2, giuseppe lembo 3, ilaria mazzini 1, beniamino mecozzi 2, brunella muttillo 3, raffaele sardella 2 1 istituto di geologia ambientale e geoingegneria (igag), cnr, roma, italy 2 dipartimento di scienze della terra, università di roma “sapienza”, roma, italy 3 dipartimento di studi umanistici, sezione di scienze preistoriche e antropologiche, università degli studi di ferrara, ferrara, italy 4 dipartimento di scienze della terra “a. desio”, università degli studi di milano, milano, italy corresponding author: f. giustini <francesca.giustini@igag.cnr.it> abstract: due to its geographic position and geomorphological configuration, grotta romanelli acted as a sediment trap since at least mis 5. the so-called ‘terre brune’ sequence is a deposit mainly of eolian origin bearing upper palaeolithic artefacts and fossil remains of vertebrate fauna; it was deposited during the glacial-interglacial transition and the holocene. sedimentology and mineralogy of this deposit are investigated. the stratigraphic sequence provides a promising archive within which both human and climatic impacts can be studied. keywords: grain size, mineralogy, holocene, grotta romanelli, southern italy 1. introduction eolian deposits have long been considered a significant resource for the past environment reconstruction. eolian activity is, in fact, modulated/influenced by global climate changes (porter, 1989) as documented, for example, in the chinese loess plateau, i.e. one of the longest and most continuous palaeoclimatic records of the quaternary interglacial-glacial cycles (ding et al., 2005). in italy, quaternary eolian deposits were described in different sites (sevink & kummer, 1984; cremaschi, 1990; narcisi, 2000; giraudi et al., 2013; boretto et al., 2017). loess deposits in northern italy and the adriatic edge of central italy were associated to periglacial environment, whereas in central and southern italy their origin was attributed to dust coming from north africa, where arid conditions during mis 4 and 2 and in the late holocene may have enhanced the dust supply in southern mediterranean sector (giraudi, 1995; narcisi, 2000). eolian deposits accumulated in caves can provide archives of past climate and human-induced changes. these deposits are additionally a significant source of information about land-atmosphere transfer processes, atmospheric residence times, land-surface depositional processes (evans & soreghan, 2015). grotta romanelli, located on the adriatic coast of southern apulia (italy), is considered a key site for the mediterranean quaternary for its archaeological and palaeontological content. the cave opens in upper cretaceous limestone (bosellini et al., 1999) at about 7.4 m above sea level, and is filled with thick deposits containing rich fossil remains of vertebrate and a wide variety of artefacts (see sardella et al., 2018 and references therein). the stratigraphic sequence, as described by blanc (1920, 1928), schematically consists (from the top to the bottom) of: (i) an upper complex, called ‘terre brune’ (‘levels a-e’), bearing upper palaeolithic artefacts and vertebrate fauna including pinguinus impennis (= alca impennis in blanc, 1927); (ii) a thin stalagmitic layer (called ‘level f’), dated at 40,000± 3250 years (fornacarinaldi & radmilli, 1968); (iii) a deposit called ‘terre rosse’ (‘level g’); (iv) a thick stalagmitic layer (‘level h’); (v) a bone breccia (‘level i’), and (vi) a beach deposit (‘level k’) fig. 1 geological sketch of the coastal area of grotta romanelli bay (sardella et al., 2018). https://doi.org/10.26382/aiqua.2018.aiquaconference referred to the tyrrhenian stage (mis 5). the ‘terre brune’ and ‘terre rosse’ deposits are considered mainly of eolian origin (blanc, 1920, 1928; blanc & cortesi, 1941); according to radiocarbon dates, the ‘terre brune’ sequence appears to span from about 9.5 to 12 ka (alessio et al., 1965; bella et al., 1958; vogel & waterbolk, 1963). in this study we provide the first results of the sedimentological and mineralogical characterization of the ‘terre brune’ deposit, which may represent a record of the holocene climate in southern italy and provide a promising archive within which both human and climatic impacts can be studied. 2. materials and methods during september 2016 the stratigraphic section ss1, located in the western sector of the cave, was selected as the representative profile for a multidisciplinary study of ‘terre brune’ deposit. the ss1, about 2.80 m thick, was cleaned, documented and sampled at a resolution of ca. 3 cm (fig. 2). ninety-six samples were collected for sedimentological and mineralogical analyses. grain sizes were determined using a cilas 1064l laser diffraction particle size analyzer (range from 0.04 to 500 μm). the grain size fractions are according to the classification of wentworth (1922). mineralogy was determined using a philips pw1840 diffractometer (cuka/ni: 40 kv and 20 ma) on bulk sediment and on clay fraction of selected samples. identification of the mineral phases was determined with xpowder12 freeware software. the calcium carbonate content (caco3 %) was measured gas-volumetrically, by addition of hcl in a dietrich-frühling calcimeter. carbon (δ13c) and oxygen (δ18o) isotopes were determined on calcium carbonate contained in sediment sieved to < 20 μm, which reacted with 100% phosphoric acid at 70°c using a thermo gasbench device connected to a delta plus mass spectrometer. results are expressed in delta per mill versus vpdb standard. 3. results field observation of the section revealed the presence of cross-laminations and large-scale ripples of variable thickness (1 10 cm). these structures are made of dark brown, cracked clayey-silt sediment, or silty sand with dull yellowish color. layers of detrital limestone, generally rich in palaeontological and archaeological remains, are also present. laboratory analyses confirmed that the grain size distribution is generally bimodal, with elevated percentages in clay (from 27 to 59%, mean 47%) and silt (from 26 to 54%, mean 44%) grain size fractions; in several samples the sand fractions are also detected. variations in these proxies along the sedimentary sequence are shown in fig. 3. the grain size records show three intervals (55 75 cm, 90 130 cm and 195 230 cm) with lower percentage of clay fraction (fig. 3a) that is counterbalanced by the content of the sand fractions (>63 μm, fig. 3c-e). x-ray diffraction shows that samples are mainly composed by quartz and minor amounts of calcite, plagioclase, feldspar. oriented xrd of the finest fraction of selected samples revealed the presence of clay minerals of the illite and kaolinite groups. the intensity of the main peak of quartz was used for a further stratigraphic record (fig. 3f). it shows that when sediments are enriched in clay fraction they are depleted in quartz and vice versa, because the fine fraction contains higher amounts of clay minerals. carbonate contents vary from 0 to ca. 12% (fig. 3g); of note is that the samples in which carbonate was not detected still contain small amounts of carbonate that are below the detection limit of the method. the interval between 90 and 190 cm comprises the largest amount of calcite particles; this part of the sequence is also particularly rich in palaeontological and archaeological remains. calcite contained in the grain size fraction <20 μm has oxygen isotope composition between -15.52‰ and 136 giustini f. et al. fig. 2 picture of stratigraphic section ss1. 137 -0.55‰ vs. vpdb. the δ18o record is shown in fig. 3h; the upper (top 70 cm) and the lower (200 280 cm) parts of the curve show several abrupt shifts towards very low isotopic values, up to -15.52‰ and -12.14‰, respectively. between 90 and 190 cm the record approximately shows uniform isotopic compositions with an average of -3.65‰; this value would indicate that the carbonate fraction at this level has mainly the contribution of the isotopic signal of the marine carbonates, then it has in prevalence detrital nature. 4. discussion and conclusion the ‘terre brune’ deposit was mainly considered of eolian origin, due to the mineralogical composition and morphology of quartz grains (blanc, 1920, 1928; blanc & cortesi, 1941). our data are in accordance with the mineralogical and sedimentological composition presented in the previous studies about grotta romanelli, and with studies from other italian sites where eolian deposits were identified (narcisi, 2000; 2001; giraudi et al., 2013). available chronology of the ‘terre brune’ (alessio et al., 1965; bella et al., 1958; vogel & waterbolk, 1963) temporally constraints the deposit to the beginning of holocene, although the lowermost portion has never been dated. preliminary results of new radiocarbon dating consistently indicate that the investigated section was formed between the late last glacial and the early holocene (calcagnile et al., 2018), when different climates occurred in the mediterranean basin. various proxy data suggested dry and cold climate condition during the late glacial, enhanced meteoric precipitation during the transition from the late glacial to the holocene, a general climate amelioration and wetter conditions during early holocene, and a change toward the present-day dry regime at 6-5 ka bp (allen et al., 1999; sadori & narcisi, 2001; bar-matthews et al., 2003; zanchetta et al., 2007; martrat et al., 2014). the sedimentological and geochemical records of the ‘terre brune’ sequence were used to reconstruct the environmental variations related to climate changes during the late last glacial and the early holocene. sediments of the lower part of the sequence (200280 cm), that may be correlated to ‘levels d-e’ of blanc (1920) stratigraphy, are progressively enriched in medium sand and depleted in clay contents; also, the quartz content increases, whereas the carbonate content is low. as the coarsening of eolian input mainly depends on two factors, the wind speed and the distance from the source areas (muhs, 2013), our data suggest that deposition of this part of the sequence occurred during a period of more intense wind transport. the source of this sediment could have been eolian dust from sahara regions. loess formed by quartz of sahara origin, was identified in several italian sites, e.g. the lago di vico and lagaccione, maar lakes in central italy (narcisi, 2000; 2001; narcisi & anselmi, 1998), the island of lampedusa (giraudi, 2004), the high mountains of the central and southern apennines (frezzotti & giraudi, 1990; giraudi et al., 2013). this phase of deposition certainly took place before 12 ka bp. at that time it is likely that a coastal plain in front of grotta romanelli was still large and it may have also contributed to the fig. 3 (a) percentage of clay (<4 μm), (b) percentage of silt (4-63 μm), (c) percentage of very fine sand (63-125 μm), (d) percentage of fine sand (125-250 μm), (e) percentage of medium sand (63-125 μm), (f) intensity of main quartz peak (cps), (g) carbonate content (caco3%), (e) δ 18o (‰ vs. vpdb) results plotted vs. depth for the stratigraphic section ss1 of ‘terre brune. levels according to blanc (1920) stratigraphy end published ages (*alessio et al., 1965; §bella et al., 1958; °vogel & waterbolk, 1963). holocene eolian deposits of grotta romanelli (southern italy) accretion of the ‘terre brune’; the coastal plain was evaluated 20 km wide at the last glacial maximum (22 ka bp), and characterized by different environments, from lagoon to wetland, possibly fringed by sand dunes (cassoli et al., 1979). palaeontological remains also indicate a terrestrial environment ranging from open semi-arid to an occasionally dried-out mud flat (sardella et al., 2018). in the interval going from 70 to 200 cm, possibly corresponding to ‘level c’ of blanc (1920) stratigraphy, the grain size distribution shows an increase of fine and very fine sands, whereas medium sand and clay decrease. an average decrease of quartz intensity also corresponds to carbonate content rise (up to 12%). the observed pattern suggests a decreased capacity of eolian energy to transport coarse particles. at this stage it is also possible that the record data respond to a progressive sea-level rise and a consequent reduction of the coastal plain which coincided with the main phase of deglaciation between ca. 11.5 ka bp (the end younger dryas) and ca. 8.2 ka bp (lambert et al., 2014). in particular the increase in carbonate content which is mainly of detrital origin, as isotopes would prove, may be considered the effect of the decrease of the eolian transport and the reduction of quartz mass capacity to dilute other mineral phases. considering that this part of the sequence is particularly rich in palaeontological and archaeological remains, it is possible to speculate that this detrital contribution could be additionally due to the human occupation. the upper part of the sequence (70 cm top) may correspond to the ‘level b’ of blanc’s stratigraphy. the sediment contains a considerable amount of clay and silt, whereas the sand fractions are virtually absent. quartz and carbonate content decrease. overall, this pattern points to a dramatically decline in the energy of eolian depositional mechanism and to an almost complete drowning of the coastal plain which cannot provide further sediments to contribute to the eolian wedge accretion. this is almost the last phase of sedimentation; the uppermost layer of the banc’s stratigraphy, the ‘level a’, was not preserved, due to both natural erosion and several years of excavations and research (sardella et al., 2018). the end of sedimentation in grotta romanelli occurred at about 6 ka bp, when 1) the coastal plain in front of grotta romanelli was greatly reduced and the sea level was about -7 m below the modern sea level (lambeck et al., 2004); and 2) prevailing wind directions changed, probably in relation with the termination of the african humid period (de santis & caldara 2015). acknowledgements we thank “soprintendenza archeologia belle arti e paesaggio per le province di brindisi lecce e taranto” (superintend dr. maria piccarreta and dr. laura masiello) for the excavation permission. we thank n. ciccarese, t. de santis, don piero frisullo and red coral (castro) for their logistical support, l. bellucci, d. a. iurino, f. strani and d. pushkina for their invaluable help during fieldwork. special thanks are due to p. plescia (cnr-igag) for grain size analyses, and s. stellino and m. preite martinez (dst-sapienza) for xrd and calcimetry analyses, respectively. the research was funded by sapienza progetto grandi scavi 2016 and 2017 (resp. r. sardella). references alessio m., bella f., bachecchi f., cortesi c. 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(2007) enhanced rainfall in the western mediterranean during deposition of sapropel s1: stalagmite evidence from corchia cave (central italy). quaternary science reviews, 26, 279-286. 139 holocene eolian deposits of grotta romanelli (southern italy) ms. received: may 15, 2018 final text received: may 21, 2018 140 available online http://amq.aiqua.it issn (online): 2279-7335 alpine and mediterranean quaternary, vol. 31 (quaternary: past, present, future aiqua conference, florence, 13-14/06/2018), 113 119 multiproxy-based reconstruction of the feeding habits from the late middle pleistocene straight-tusked elephant population of poggetti vecchi (southern tuscany, italy) chiara capalbo dipartimento di scienze della terra (dst), università di firenze, firenze, italy dipartimento di scienze della terra e del mare (distem), università di palermo, palermo, italy corresponding author: c. capalbo <chiaracapalbo@gmail.com> abstract: the palaeodietary preferences from the elephants of poggetti vecchi, which radiometrically dated around 171,000 years bp, have been investigated by cross-comparing the results obtained with low-magnification analysis of microwear (ldm), 2d-roughness parameters and surface geometry assessment, mesowear and stable isotope analysis. proboscideans tend to be opportunists, and this improves their ability to respond to climate impacts and environmental fluctuations. the dietary signal of the last meals suggests the consumption of a great amount of graminaee or other plants quite rich in phytoliths. conversely, mesowear data indicate more browsedominated, mixed dietary behaviour, which probably reflects seasonal variations, and environmental changes. keywords: palaeodietary, early middle pleistocene, palaeoenvironment, palaeoloxodon 1. introduction modern elephants are regarded as a particular kind of mixed-feeders with complex behaviour. depending on the availability of different kinds of plants, as well as on climatic conditions, they show most variable feeding habits. microwear patterns can therefore change considerably and rapidly both seasonally and geographically (grube et al., 2010). despite all the potential interpretative biases (which may derive from morpho-functional variations in the chewing apparatuses, the involvement of contaminants, post-mortem alterations, methodological inconsistencies, the use of inappropriate instruments and analyst's skill) conventional dental microwear analysis is a powerful tool and still preferable to other methodologies, first of all because it is the easiest way for functional morphologists to investigate and obtain relevant information from microwear patterns. moreover, it permits to analyse large numbers of samples at lower costs using basic equipment. however, a reliable quantification of the smallest scars may exceed the capacities of light microscopy, which would thus impose the use sem or other instruments capable of investigating three-dimensional surface texture. for the present study we adopted an alternative, multiproxy and comparative approach which is based on a combination of different methods. our results concern dietary signals of last meals, obtained with low-magnification analysis of microwear (ldm), and carbon and oxygen determination of enamel fraction, which reveals the dietary history of earlier phases of an individual's life. we also used the mesowear method, which reflects specifically the abundance of grasses that are present in the habitats where animals live and not just the openness of the landscape. the mesowear method was recently extended to proboscideans (saarinen et al., 2015). it records dietary signals over long time spans. left and right molars of each individual can show different mesowear angles (probably due to one-side chewing habits); changes also occur throughout the life of an individual, including seasonal shifts in dietary preferences (e.g., sukumar & ramesh, 1995; cerling et al., 2006, 2009; rivals et al., 2012). mesowear signals can therefore record seasonal variations in an elephant’s feeding habits. any surface can be described as a complex landscape with peculiar geometric form and textural alterations (waviness and roughness). surface textures that appear smooth at coarse scales can be demonstrably rough at sufficiently fine scales. worn enamel finds correspondence with industrially manufactured surfaces. all surface measuring systems reconstruct 3d surface models by assembling line profiles. however much more detailed information about the enamel wear is encapsulated in 2d-roughness parameters rather than 3d-models. hence the 2dsurface data and geometric pattern employed in this study can be used to characterize the physical topography of enamel facets, quantifying the universal attrition– abrasion equilibrium controlling dental wear and to classify individuals into feeding categories. the results of pooled analysis show that the use of different methods is a potentially more effective way to constructively address the many issues on the feeding adaptations of extinct elephants than is relying on only one method. the methodology used in this study reveals the wealth of information that a multiproxy approach can contribute in studies aimed at palaeodietary and palaeoenvironmental reconstructions. in addition, these results seem to agree with preliminary environment reconstruction based on both palaeobiological and taphonomic investigation, as well as with preliminary https://doi.org/10.26382/aiqua.2018.aiquaconference geoarchaeological insight. the poggetti vecchi area (42°49'8.92" n, 11° 4'19.41" e) is located in southern tuscany (central italy), some 7 km northwest of grosseto. an in-depth palaeoenvironmental reconstruction of the site of poggetti vecchi, obtained combining archaeo -palaeontological records and sedimentological data, can be found in benvenuti et al. (2017). 2. materials and methods fifteen upper and lower molars of both sides and of a fairly wide spectrum of ontogenetic ages were used to perform both microwear and mesowear analyses. a list of the selected molars, together with a summary description of them, is reported in tab. 1. in this study, the capital letters represent upper cheek teeth (e.g., m1), while lower case letters indicate lower teeth (e.g., m3). molds and casts were prepared by adapting the methods described by solounias & moelleken (1992a) and solounias & semprebon (2002). they were then examined under a zeiss standard light stereomicroscope at 40 and 100x magnification using a unidirectional external oblique light source with a shallow incidence angle. several microphotographs were taken at both magnifications; the latter gave the best-resolved images of the elephant teeth, providing a visual field of 2 mm 2 (todd et al., 2007). qualitative and quantitative investigation of microwear scars was carried out directly on computer using the software imagej, focusing on functional plates. we performed the following actions: 1) calculated the total number and frequency of scratches and pits; 2) measured the average length and width of the scars; 3) used width/length ratios to discriminate fine from coarse scratches and small from large pits; 4) expressed microwear density as number of features per analysed area. we measured the carbon and oxygen isotope composition of the enamel of a second molar (n. 1365). a fraction of the enamel was mechanically cleared of dentine and cement using tungsten-carbide rotary tools and finally ground with an agate mortar. the purity and crystallinity of the fine enamel powder was monitored by xray diffraction analysis. a randomly oriented powdered sample was mounted on glass slides and scanned. the diffraction pattern was collected on a philips pw 1050/37 diffractometer using graphite-monochromatised cukα radiation, obtained at 40 kv and 20 ma. the sample was scanned from 5° to 60° with a step size of 0.02° 2θ and a counting time of 2s. following chenery et al. (2012), the sample was not subjected to leaching pre-treatment; about 150-200 mg of enamel powder was reacted with 100% orthophosphoric acid (h3po4) at 25°c for three days to produce co2, which was then collected by cryogenic separation. finally, the isotope compositions were measured by finnigan mat 252 mass spectrometer. the oxygen isotope value (δ 18 osc versus pdb-1) was obtained from the structural carbonate; using daux et al.’s (2008) equation it was directly translated into the isotope composition of the environmental water δ 18 ow versus smow). the mesowear angles were measured on detailed profiles obtained using a burton’s steel professional comb. the contour gauges were used to identify the dentine valleys; following saarinen et al.’s (2015) indication, the mesowear angle measurements were taken using a digital goniometer with 0.1 precision. the average angular values were estimated based on angle measures of the three central lamellae of each molar. the results were then compared with those reported by saarinen et al. (2015). finally, following the indications given by saarinen & lister (2016), the average mesowear angles were correlated with the percentages of the pollen of non-arboreal species (nap) and, in particular, of poaceae, to evaluate how much local vegetation is reflected by the inferred dietary habits. two representative specimens (the adult n. 5500 and the calf n. 98) have been selected for topographic assessment based on 2d-roughness parameters and geometric patterns. the casts were scanned by a digital microscope (hirox kh-7700). the auto multi focus tool enabled the creation of 3d images obtained by composing a set of fifteen planes taken at different focuses with a vertical step ranging from 4 to 8 µm (depending on the topographic features of the sample). on the samples surface, a rectangular area of about 450x600 µm was scanned at 0.381 µm resolution using a 500x objective; almost three rois (regions of interest) were selected at the center of the two central enamel loops of the teeth and scanned to inspect if and how the surface texture varies on each sample. the software mountainsmap7® image (digitalsurf, france) was used to obtain 2d images of the topography of the acquired areas. almost 10 roughness profiles along with iso 4287 (1997) standard parameters, were extracted from each image by applying a gaussian filters to clean the raw data. 2droughness parameters are extensively described in kaiser & brinkmann (2006). mountainsmap® also includes tools specifically designed to assess fractal dimension (a statistical index of complexity) and isotropy by processing digital maps. finally, 3d reconstructions were here obtained by the use of interactive 3d-surface plot plugin of imagej software, which creates interactive surface plots (i.e., dots, lines, mesh, filled, display colors, etc.) from all kinds of images. 114 capalbo c. tab. 1 description of the specimens used for microwear inspection, mesowear and surface texture assessment. 115 3. results the qualitative microwear analysis revealed that microwear patterns are similar all over the occlusal surface. microwear features are most variable on both the lingual and buccal sides of each functional plate, whereas pits and scratches are most variable on distal plates. qualitative and quantitative analyses and measures confirm that scratches (fine, mixed and coarse) outnumber pits on each of the teeth examined. furthermore, coarse features are usually more frequent at the centre of the enamel loops, whereas fine ones (which are usually longer, narrower and shallower) are mainly concentrated along their edges. cross-coarse scratches are particularly abundant in the middle section of molar teeth; also pits (either large, mixed, or small ones) can be abundant locally, especially on buccal and lingual sides. the microwear patterns observed in this analysis are summarized in fig. 1. xrd graph plot revealed the absence of impurity phases; the diffraction pattern shows a peak characteristic of apatite (fig. 2). its value is rather similar to that of the enamel phase of the teeth of modern and fossil elephants (ayliffe et al., 1994). the carbon isotopic value of the enamel structural carbonate (-11.05‰ δ 13 csc versus pdb-1) and the corresponding calculated palaeodiet (-25.14‰ δ 13 cdiet versus pdb-1) suggests that the straight-tusked elephant population of poggetti vecchi falls in the ‘‘c3-dominated diet’’ field. in tab. 2 are reported the oxygen isotope value or structural carbonate and the environmental water isotope calculations. the mean acute mesowear angles vary considerably in each specimen, ranging from 90.95° to 119.82°: in the population as whole, the angle measurements vary from 102.63° to 119.82°. the regression analysis that is shown in fig. 3, as well as the comparison of the mean mesowear angles with the relative graminae pollen frequencies (fig. 4) calculated at poggetti vecchi (m. mariotti lippi personal communication) indicate that our population had browse-dominated mixed diet with relatively flexible feeding behaviors. only a small subset of 2d-roughness parameters seems to characterize more efficiently the enamel texture and dietary categories, which are listed in tab. 3, where geometry calculations are also included. the fractal dimension (fig. 5) was found to be rather similar in both the poggetti vecchi specimens ranging from 2.59 and 2.74. the orientation of roughness features (isotropy/anisotropy texture), which is expressed as the tree main angular values and isotropy percentage, is shown in fig. 6. the latter are more heterogeneous in the specimen 5500, varying from 18.6 to 40.9%, whereas the average value in the specimen 98 is 31.50%. 3d-reconstructions of the enamel samples are shown in fig.7. men and elephants in prehistoric maremma fig. 1. % of pits vs % of scratches scatter diagrams at 100x magnification. a) average percentage of pits plotted against average percentage of scratches; b) average density of pits plotted against average density of scratches; c) average length of scratches plotted against the average width of scratches. fig. 2 xrd pattern of the dental enamel sample analyzed for this study. tab. 2 carbon and oxygen isotope enamel determination and palaeodiet calculation. 116 fig. 3 linear regressions of δ 13 c values from tooth enamel and mean mesowear angles. value obtained from the poggetti vecchi molar compared with data drawn from saarinen et al. (2015). the 95% confidence limits are shown as dashed lines (coefficient r 2 = 0.92, student’s t-tests p < 0.001). fig. 4 regressions between mean mesowear angles and mean poaceae (grass) %. values obtained from poggetti vecchi molars compared with data drawn from saarinen and lister (2016). (coefficient r 2 = 0,00133. student’s t-tests p = 0.001). tab. 3 a selection of 2d-roughness texture parameters and geometric patterns employed in this study and corresponding average values. fig. 5 example of fractal dimension analysis calculation for one the selected enamel rois studied for the molar n. 98 following the enclosing boxes method [with the slope and correlation coefficient (r 2 ) of regression line]. fig. 6 polar diagrams showing texture direction and related parameters of the three selected enamel rois studied for the molar n. 98. fig. 7 example of 3d-surface models obtained by assembling roughness line profiles. capalbo c. 4. discussion and conclusion our results were compared with the average numbers of pits and scratches observed in modern and extinct taxa, as they are reported in the literature; the corresponding dietary morphospace are shown in fig. 8. the high percentage of mixed and fine scratches associated with abraded micro-areas observed on the teeth from poggetti vecchi indicates feeding on abrasive food, containing high amounts of opal phytoliths, but also the ingestion of soil particles picked up with grasses. our elephants cluster within the grazer dietary morphospace. differences between the various italian palaeoloxodonts may indicate different dietary preferences, as well as a high plasticity to adapt to local environmental and microclimatic conditions. modern elephants increase grass intake during more humid periods (sukumar & ramesh, 1995); if the poggetti vecchi elephants behaved similarly, the microwear pattern here obtained is indicative of grass consumption under rather cold and wet climatic conditions. we could determine the isotopic concentration of only a single sample, and hence the range of variability is not known. consequently, the results on the palaeodietary habits of these italian middle pleistocene straight -tusked elephants and on the palaeoenvironmental conditions under which they lived are essentially inferred based on comparisons with published data on straighttusked elephants from other sites, namely la polledrara and casal de’pazzi, in italy (palombo et al., 2005), and neumark nord 1, in germany (grube et al., 2010). the carbon isotope of the structural carbonate in the enamel fraction from poggetti vecchi reaches -11.05 ‰, and the corresponding calculated δ 13 c value of the diet thus is 25.14‰ and falls into the field of c3 plants. the overall δ 13 c values of the diet in comparative samples vary 117 fig. 8 bivariate plot of the average number of scratches versus the average number of pits and corresponding feeding morphospace envelopes (leaf browsing, fruit browsing, grazing, seasonal and meal by meal mixed-feeders taxa). data for extant ungulates and elephants were drawn from solounias and semprebon (2002) and those of palaeoloxodonts specimens from neumark nord 1, la polledrara di cecanibbio and casal de’pazzi were drawn from grube et al. (2010). men and elephants in prehistoric maremma from -23.1‰ to -28.1 (grube et al., 2010). the collective data drawn from the literature indicate that the average climatic and environmental conditions inferred for the elephants from the so-called “campagna romana” and from neumark nord 1 were similar to those that existed at poggetti vecchi. the water δ 18 ow at poggetti vecchi (-6.18 ‰) is slightly more positive than those calculated for the comparative samples (palombo et al. 2005; grube et al., 2010); in addition, it seems in equilibrium with the isotopic values of modern local precipitations (which range from -6‰ to -7‰; giustini et al., 2016). we can therefore conclude that the poggetti vecchi elephants likely relied on two sources of drinking water, i.e., ponds/lakes (filled with local rainwater) and rivers. our results are in line with the general environmental scenario for the middle pleistocene of central italy. the isotopic signature of enamel is consistent with a landscape dominated by wooded grasslands, under colder and/or wetter conditions than the present ones. the dietary shift towards more grazing habits in the poggetti vecchi population of palaeoloxodon antiquus can be a response to more humid conditions; in other words, the poggetti vecchi elephants had to turn to grass-eating, as living elephants do today in special seasonal circumstances. the results here presented confirm that microroughness features can be effectively described using 2d-roughness criteria, as previously inferred by kaiser & brinkmann (2006), as well as using geometry calculations. the selected subset of parameters is capable to measure the scale of surface alterations recorded by the system and, consequently, capture conventional microwear signals. in this study roughness parameter calculations fall within the thresholds of grazerdominated animals with mixed-feeding habits. the polar spectrum shows that the angular data vary widely, which indicates the lack of mainly unidirectional structures and, therefore, the absence of strong anisotropy signals. this is corroborated by the relatively higher average values of the fractal dimension calculations, which clearly indicate that both molars (m3 n.5500 and m1 n. 98) here studied have quite complex surface textures. compared to the other methods here considered mesowear is faster, not exposed to the risks of contamination, non-destructive, easy-to-do and widely applicable. it provides a direct indication of the amount of abrasive and nonabrasive plants regardless of the photosynthetic pathways employed by the terrestrial plants, and allows the detection of c3-grazing, more directly than using δ 13 c values. based on the mesowear results, the poggeti vecchi straight-tusked elephants had a browsedominated, mixed diet with relatively flexible feeding behaviors. the weak positive correlation between the mean angle measure and the percentage of poaceae pollen confirms this indication. this mismatch could be essentially due to differences in the temporal resolution of microwear and mesowear methods. in addition, considering that palaeoloxodonts shifted from more browsing or mixed-feeding to more grazing in accordance with local context, mesowear is probably more effective than microwear in capturing the minimum seasonal variations in diet. acknowledgements special thanks go to francesco landucci for supporting me during the preparation of molds and casts, to orlando vaselli for logistics support and for granting me access to the geochemistry lab. i am grateful to jacopo crezzini and francesco boschini (university of siena) and simona raneri (university of pisa) for helping me with topographic and roughness analysis. references ayliffe l.k., chivas a.r., leakey, m.g. 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(2010) what did the fossil elephants from neumark nord eat? in: h. meller (ed.), elefantenreich eine fossilwelt in europa. lansdmuseum fur vorgeschichte, halle, 253-272. isbn 978-3-93941448-3. iso 4287 (1997) geometrical product specifications (gps) surface texture: profile method terms, definitions and surface texture parameters. replaces iso 4287-1, 1984. 118 capalbo c. kaiser t.m., brinkmann g. (2006) measuring dental wear equilibriums the use of industrial surface texture parameters to infer the diets of fossil mammals. palaeogeography, palaeoclimatology, palaeoecology, 239, 221-240. palombo m. r., filippi m., iacumin p., longinelli a., barbieri m., maras a. (2005) coupling tooth microwear and stable isotope analyses for palaeodiet reconstruction: the case study of late middle pleistocene elephas (palaeoloxodon) antiquus teeth from central italy (rome area). quaternary international, 126-128, 153-17. rivals f., semprebon g., lister a. 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(1995) elephant foraging: is browse or grass more important? in: daniel j. c., datye h. (eds.), a week with elephants. bombay natural history society, bombay, india, 368-374 todd n. e, falco n., silva n., sanchez c. (2007) dental microwear variation in complete molars of loxodonta africana and elephas maximus. quaternary international, 169-170, 192-202. 119 men and elephants in prehistoric maremma ms. received: may 7, 2018 final text received: may 21, 2018 120 base mammal fossil record, depositional setting, and sequence stratigraphy in the middle-upper pleistocene of roman basin maria rita palombo 1,2 & salvatore milli 1,2,3 1dipartimento scienze della terra, università sapienza, roma 2cnr, istituto di geologia ambientale e geoingegneria, roma 3 isipu, istituto italiano di paleontologia umana corresponding author: m.r. palombo <mariarita.palombo@uniroma1.it> abstract: palombo m.r. & milli s., mammal fossil record, depositional setting, and sequence stratigraphy in the middle-upper pleistocene of roman basin. (it issn 0394-3356, 2010) in the roman basin, and particularly in the ponte galeria area, quaternary vertebrate remains are preserved both in continental and marine sedimentary successions. the facies and sequence stratigraphical analyses carried out in the last twenty years on such deposits led to a detailed local chronostratigraphical framework which fixes some physical and temporal limits to the fist/last local appearances of some mammalian taxa. this contributes to a better definition of faunal complexe, characterizing the biochronological setting proposed for the quaternary large mammal faunas of the italian peninsula. riassunto: palombo m.r. & milli s., record fossile a mammiferi, assetto deposizionale e stratigrafia sequenziale della successione del pleistocene medio-superiore del bacino romano. (it issn 0394-3356, 2010) nel bacino romano, ed in particolare nell’area di ponte galeria, resti di vertebrati quaternari sono presenti in successioni sedimentarie sia continentali sia marine. l'analisi di facies e stratigraficosequenziale condotta su tali depositi nel corso degli ultimi venti anni ha portato ad un dettagliato inquadramento cronostratigrafico dei depositi e ha consentito di fissare limiti temporali per la prima comparsa di alcuni taxa, in particolare grandi mammiferi fra cui specie non ancora segnalate nel resto della penisola, contribuendo così ad una migliore caratterizzazione dello schema biochronologico proposto per le faune a grandi mammiferi del quaternario della penisola italiana. key words: large mammals, biochronology, sequence stratigraphy, pleistocene, roman basin. parole chiave: grandi mammiferi, biocronologia, stratigrafia sequenziale, pleistocene, bacino romano. il quaternario italian journal of quaternary sciences 23(2), 2010 257-262 1. introduction the sedimentary cyclicity characterizing the quaternary stratigraphical record represents an outstanding example on how climate and glacio-eustatic signals could affect the stratigraphical setting of sedimentary successions. the quaternary sedimentary record of the roman basin hightlights this climate-driven cyclicity by a continuous modification of landscape and of depositional environments. moreover, the peculiar environmental conditions and the paleogeographical setting of the latium area during the middle-late pleistocene (fig. 1) promoted the diffusion of a rich mammal fauna and their postmortem preservation in deposits of different sedimentary environments. the latters mainly range from transgressive fluvial and fluvio-palustrine deposits, filling incised valleys (tst), to highstand barrier island–lagoon deposits (hst) (milli et al., 2008). 2. geological and sequence-stratigraphical setting the investigated area is located along the latium tyrrhenian margin that has undergone extensional tectonic processes since the late miocene, in connection with the opening of the tyrrhenian basin, and intense volcanic activity that reached a climax in the middlelate pleistocene. during the pleistocene the geological and palaeogeographical evolution was controlled by the close interaction among three main processes: the glacioeustatic sea-level fluctuations related to quaternary climatic changes, the volcanic activity, and the tectonic uplift of the latium tyrrhenian margin. starting by the pioneering work by c onato et al . (1980), the pleistocene succession mainly cropping out in the ponte galeria area was subdivided into informal lithostratigraphic units named, from the oldest to the youngest, monte mario formation (lower pleistocene, ‘calabrian’), and ponte galeria, s. cosimato, aurelia, and vitinia formations ranging in age from the latest early pleistocene to the late middle pleistocene (‘ionian’) (fig. 2). in the last years, the stratigraphic resolution of sedimentary successions has notably improved due to development of sequence stratigraphic concepts. thanks to this methodology, the spatial-temporal relationships between terrestrial and marine depositional systems in relation to sea-level changes have been better defined. basing on a detailed facies and physical stratigraphic analysis of the pleistocene/holocene sedimentary succession, milli (1992, 1994,1997, 2006) refined the stratigraphy of the 258 m.r. palombo & s. milli area defining several fourth-order sequences, stacking to form two composite third-order sequences named monte mario sequence (mms) and ponte galeria sequence (pgs) (fig. 1). most of the mammal remains are contained in the pgs. the pgs extends for about 30 km, in nw-se direction, along the latium coastline; in the area between roma and the coastline its thickness varies from 10-15 m to 100-110 m, depending on the intensity of the erosional phases connected with cyclic, recurrent lowerings of relative sea level. the pgs consists of ten 4th-order sequences with an approximate period of 100,000 years (fig. 1); the boundaries of these high-frequency sequences are expressed by sharp erosional surfaces, recording basinand downward shifts of facies, subaerial exposure and by paleosols in the interfluve areas, which put in contact sediments belonging to different depositional systems (milli et al., 2008 and references therein). the fourth-order depositional sequences are characterised by a seaward stack, which is opposite to the trend that the pgs would have had if controlled by glacio-eustasy alone. this trend is though to be the result of the close interaction between high frequency sealevel fluctuations related to glacio-eustasy and the tectonic uplift, which comprises also a local volcanicallyinduced component, particulartly strong during the late quaternary time, that affected the latiumtyrrhenian margin during the middle-late pleistocene. in particular the lower four 4th-order sequences (pg0 to pg3) stack to form the early lst, which developed during a period of relative sea-level fall producing a series of prograding and downstepping wedges-shaped high-frequency sequences. stratigraphical relationships between pg4 and the underlying sequences enable us to assign it to the late lst, whereas sequences from pg5 to part of pg8 can be ascribed to the tst, and the sequence pg9 entirely to the hst (fig. 1) (milli et al., 2008). 3. mammalian remains from the ponte galeria sequence: biochronological framework in the rome urban area, a molar tooth of mammuthus meridionalis has been found in the marine sands of the mms, attributed to the lower pleistocene (santernian), while in the in the area between rome and the latium coastline, most of the mammalian remains come from both continental and marine sediments of the pgs (fig. 1,3). particularly, in the ponte galeria area, the richest local faunal assemblages (lfas) come from the pg2, pg3 and pg4 4th-order sequences, developed during a period of long term (i.e. related to the 3rd order cyclicity) average sea-level fall and initial rise. fossil bones have been found in transgressive fluvial and fluvio-palustrine deposits filling incised valleys (tst) and in highstand barrier island-lagoon deposits (hst) of the 4th order sequences (see milli & palombo, 2005; milli et al., 2008). remains from pg2 to pg4 sequences represent the “classic italian galerian fauna” (see ambrosetti, 1967; ambrosetti et al., 1972) ascribed to the middle galerian land mammal age (lma) (gliozzi et al., 1997; palombo, 2009). few teeth of “cold” fig. 1 integrate chronostratigraphy and sequence stratigraphy of the pleistocene deposits of the roman basin and biochronological setting of italian mammal faunas. small mammals ( prolagurus pannonicus and predicrostonyx sp., ponte galeria 1 lfa) have been retrieved from the lacustrine lagoonal deposits of pg1 sequence (fontignano, helicella clay), which recent paleomagnetic data have attributed to an inverse polarity (see kotsakis et al., 1992; marra et al., 1998). these data, together with stratigraphic and sedimentological data, (see, milli, 1997) indicate that these sediments were deposited during a cold climate phase (mis 20); they have been also attributed to the late lowstand systems tracts of the pg1 sequence (milli, 1997). in the beach sand and gravel deposits underlying the venerupis senescens clays (hst of sequence pg2, whose age roughly ranges from 0.72 to 0.68 ma) the first local appearance (fla) of crocuta crocuta, mammuthus trogontherii, megaloceros savini, and hemibos galerianus represents also the lowest occurrences of these taxa in the italian peninsula (fig. 3). among other taxa retrieved from these deposits, equus altidens first appeared in italy during the latest villafranchian, stephanorhinus hundsheimensis and praemegaceros verticornis are first recorded shortly before and at the beginning of the jaramillo subchrons, whilst palaeoloxodon antiquus, cervus elaphus acoronatus and bison schoetensacki appeared in the latest early pleistocene (palombo, 2009 and references therein). the appearance of spotted hyaena would suggest that this lfa (ponte galeria 3 lfa, palombo, 2004, 2009) would be younger than the slivia lfa (northeastern italy), where pachycrocuta brevirostris is 259mammal fossil record, depositional setting, and ... still present. but, is this enough to support the petronio and sardella’s hypothesis (petronio & sardella, 1999) according to which slivia lfa and ponte galeria 2 lfa belong to two distinct faunal units? taking into account the doubtful identification of some main herbivores of the slivia local fauna, as well as the scanty knowledge of small mammals belonging to ponte galeria 2 lfa, the possibility that slivia and ponte galeria lfas belong to the same fu cannot be ruled out (see palombo, 2004, 2009). moreover, much more data need to clarify the dynamics of c. crocuta/p. brevirostris replacement in the western mediterranean, where p. brevirostris and c. crocuta seem to have been both present across the early/middle pleistocene boundary. for instance, in the iberian peninsula p. brevirostris is recorded during the latest pleistocene at vallparadís (terrassa, catalonia) in deposits correlated with mis 21 (madurell-malapeira et al., 2010), while c. crocuta is present, just before the matuyama/bruhnes boundary transition, in the td6 level from gran dolina (atapuerca, north spain) (cuenca-bescos & garcia, 2007). the laf (ponte galeria 3) from the hst beach deposits and the lacustrine-palustrine deposits of pg3 sequence (about 600-550 ka) (fig.1,3), counts several vertebrates remains (birds, amphibians and reptiles, small and large mammals), among which the vole arvicola mosbachensis (milli & palombo, 2005; sardella et al., 2006) confidently confirms that the lfa can be ascribed, together with the almost coeval isernia la fig. 2 – high-resolution strathigraphical cross-section and depositional setting of the third-order ponte galeria sequence (pgs) between the town of rome and the latium coastline (modified after milli, 1997). 260 pineta lfa (central italy) (coltorti et al., 2005, and references therein) to the oldest toringian fauna recorded in italy to date (sala & masini, 2007) (fig. 1,3). the ponte galeria 3 lfa is fairly rich and diversified, including together with allocricetus bursae, a primate (macaca sylvanus), a few carnivores such as meles meles, lynx sp., a hyaena whose taxonomical identification is still matter of debate, (‘‘hyaena prisca’’ = pliohyaena perrieri according to turner et al. 2008), as well as large (stephanorhinus cf. s. hundsheimensis, equus altidens, equus suessenbornensis, hippopotamus ex gr. h. antiquus, bison cf. b. schoetensacki) and middle-sized herbivores (sus scrofa priscus, “pseudodama” sp., cervus elaphus acoronatus) (caloi & palombo, 1986; petronio & sardella, 2001; milli & palombo, 2005). in deposits of about 500 ka belonging to the hst of the pg4 sequence, some vertebrate remains (testudinata, some bones of a disarticulated skeleton of palaeoloxodon antiquus, hippopotamus sp., dama sp., and bos primigenius) have been found at the casal selce quarry (casal selce 2 lfa) (milli et al., 2005). these deposits are represented by fluvial braided sandy deposits at the base, passing upward to lagoonal mud and silty-sands and muds of palustrine-lacustrine environment (milli, 1997). the deposits are characterized by a high component of volcaniclastic material (ranging in age between 500 and 485 ka, see karner & renne, 1998; karner & marra, 1998), which was emplaced through fall events (milli et al., 2008). the lfa could be ascribed to the late galerian fontana ranuccio fu, as well as the sporadic remains of late galerian taxa that have been uncovered in sediments interbedded with the sabatini volcaniclastic deposits (tufo giallo della via tiberina or tufi stratificati varicolori di sacrofano) (e.g., cervus elaphus eostephanoceros, hippopptamus ex gr. h. amphibius). new studies carried out on the incomplete skull of ovis ammon antiqua reported by portis (1917) as hypothetically retrieved from deposits overlaying the “pozzolane grigie” in the magliana area, enable us to clarify that the argali skull is at least younger than the beginning of the volcanic activity in the study area and to hypothesize that it was possibly found in the tst/hst lacustrine-lagoonal deposits of the pg4 sequence (see rozzi et al., in press for a discussion). accordingly, the incomplete skull of ovis ammon antiqua should be referred to the fontana ranuccio fu and regarded as penecontemporaneous with or slight older than the argali from visogliano (northeaster italy), the only other specimen of such a rare species thus far recorded in italy (abbazzi et al., 2000; falgueres et al., 2008). lfas belonging to aurelia formation/pg6 and vitinia formation/pg7 (fig. 1) sequence are characterized by the association of palaeoloxodon antiquus with large bos primigenius, accompanied by cervids (dama clactoniana, dama dama tiberina, cervus elaphus, capreolus capreolus and megaloceros giganteus), while equus ferus may be present, at times in abundance, and equus hydruntinus sporadically occurs. rhinoceroses (stephanorhinus hemitoechus, s. hundsheimensis and s. kirchbergensis), hippopotamus, wild boar and middlesized carnivores (canis lupus, vulpes fig. 3 biochronology of selected large mammals found in the monte mario and ponte galeria third-order sequences (roman basin). m.r. palombo & s. milli 261 vulpes) are often present, while the large (ursus spelaeus, panthera spelaea, panthera pardus) and small (mustelidae) carnivores are poorly documented (palombo et al., 2003 and references therein; milli et al., 2008). these lfas can be referred to the early aurelian lma (torre in pietra fu) (see palombo et al., 2004; palombo, 2009 for a discussion). 4. remarks in the roman basin, the vertebrate remains collected from the high-frequency depositional sequences should be ascribed to faunal complexes with a temporal range comparable to the range of the high-frequency sequences. although the possibility of exhumation exists, the type of fossil remains, their mode of preservation, and the characters of the depositional environments suggest that faunal remains have the same age of the deposits within which they are contained. accordingly, the sequence-stratigraphic framework as well as the radiometric and palaeomagnetic data (see milli, 1997; karner et al., 2001; marra et al., 2008 and references therein) enable us to constrain the age of the lfas, to better calibrate bioevents both with the geochronology and oxygen isotope signals, and to improve our knowledge on local highest occurrences/last appearances of mammal taxa in the italian peninsula. acknowledgments the authors thank the anonymous reviewers for their comments to the manuscript. references abbazzi l., fanfani f., ferretti m. p., rook l., cattani l., masini f., mallegni f., negrino f., tozzi c. 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(2008) taxonomy and evolutionary patterns in the fossil hyaenidae of europe. geobios 41 (b), pp. 677–687. ms. ricevuto il 4 agosto 2010 testo definitivo ricevuto il 18 novembre 2010 ms. received: august 4, 2010 final text received: november 18, 2010 m.r. palombo & s. milli microsoft word 00_indice_lm04.docx il quaternario it issn 039-3356 italian journal of quaternary sciences 24 (1), 2011 5-9 alberto malatesta geologist and palaeontologist francesco zarlenga enea cr.casaccia (utrinn), roma corresponding author: <francesco.zarlenga@enea.it> alberto malatesta, former professor at the rome university sapienza in the master course of geological sciences, geologist and palaeontologist, passed away when he was 92 years old on 9th october, 2007. a. malatesta was born in livorno the 15th of july 1915; there he attended classic studies at the secondary jesuit school “niccolini-guerrazzi” and obtained his degree on 1933. he graduated in natural science at the pisa university, tutored by prof. alberto carlo blanc. immediately after the degree he started to teach science at the secondary school of piombino; there he met miss gianna torricelli, who became his wife some years later. they had three children: giuseppe, gabriella and giovanna. during 1939, a. malatesta abandoned teaching and left for east africa (ethiopia) as a geologist of the reale corpo delle miniere. in this period he mainly studied the geology of the awash valley (unfortunately only in very recent times important fossil remains were discovered there). at the beginning of the second world war he was in ethiopia as second lieutenant of the italian army. after a romantic adventure spent flying between ethiopia and eritrea, he was captured and kept prisoner by the english troops. a very serious form of malaria stopped his run and he was transferred first to the asmara harbour and then to the english war prisoner camp at peshawar (pakistan). notwithstanding his prisoner status, after the 8th september 1943 he was able to carry out some scientific missions on the himalayan range and in very interesting paleontological areas. the observations made during these field surveys were published some years later on the scientific journals atti della società toscana di scienze naturali (1948) and bollettino del servizio geologico d’italia (1951). during 1948, he came back in italy and, starting from 1950, he was employed by the italian “servizio geologico nazionale”. there he worked as a field geologist and carried out the geologic survey of several 1:100.000 geological sheets in central and southern italy, sardinia and sicily. this activity gave him a huge knowledge of the italian quaternary geology and the possibility to gather a very large collection of fossil remains that he studied during the following years. f. zarlenga 6 a. malatesta attained the “libera docenza” in palaeontology in 1959 and he became associate professor of palaeontology in 1981. he taught “palaeontology” at the messina university (1960-1962) and at the sapienza università di roma (1962-1973). at the sapienza università di roma he gave also the courses “quaternary geology and palaeontology” (1973-1975 and 1981-1985) and “vertebrate palaeontology” (19751981). during this period he headed several paleontological expeditions in crete, sicily and sardinia caves. he retired on november 1985 when he was 70 years old, but he did not stop his research activity as testified by several scientific publications dated up to 1994. a. malatesta has been author or co-author of 104 scientific papers dealing with pliocene and quaternary geology and geomorphology, invertebrate (molluscs) and vertebrate (insular quaternary mammals) palaeontology and palaeoethnology. in his book on quaternary geology and palaeontology, he synthesized the general scientific approach to the study of quaternary problems on the base of his own field experiences and his huge global geo-paleontological culture. among the most important results deriving form the scientific activity of a. malatesta it is possible to mention his synthesis of the quaternary geology of the roma surroundings (1978, 1980) and his many contributes to the knowledge of the italian plio-quaternary paleontology. born first as a geologist, his biological and paleontological preparation, gained at the pisa university when he was a student, lead him to solve some problems met during the geological surveys with the aid of taxonomical and palaeoenvironmental studies on mollusc and vertebrate remains. he studied fossil molluscs collected in the quaternary of sicily, in the pliocene of umbria and in the paleocene of mozambique, writing important monographies (among which the “malacofauna di grammichele”, 1960, 1963 and the “malacofauna pliocenica umbra”, 1974). such monographies are benchmarks for the italian, and in some cases, for the worldwide mollusc palaeontology. studying molluscs he erected 1 new genus, 1 new subgenus, 22 new species and 3 new subspecies. at the same time, the recovery of dwarf cervids during his geological surveys in sardinia aroused his interest on the phenomena of “nanism” and “gigantism” of insular mammalian taxa and induced him to organize several paleontological expeditions in sardinia, sicily and crete. these experiences lead him to propose a new model for the mammal population of insular districts and the consequent endemism (1980). he erected 1 new genus, 1 new subgenus and 3 new species of mammals. under his guide, a roman school on vertebrate palaeontology was born and several researchers at the sapienza università di roma and at roma tre university still carry on his heritage today. list of publications malatesta a. (1939) sul rinvenimento di alcuni nuovi esemplari fossili di arbacia. boll. soc. geol. it., 58, pp. 1-5. bacci a., malatesta a., tongiorgi e. (1939) di una formazione glaciale rissiana riscontrata a livorno nei sedimenti della fase costruttiva del ciclo tirreniano. atti soc. tosc. sci. nat. proc. verb., 48, pp. 74-85. malatesta a. (1940) ricerche di preistoria nella provincia di livorno. boll. stor. liv., 4, pp. 1-15. malatesta a. (1940) l’industria musteriana di livorno. atti 28ma riun. soc. it. sci. nat., 4, pp. 367-370. cecioni g. & malatesta a. (1940) le valli del torrente chioma e del rio popogna nei monti livornesi. natura, 31, pp. 62-69. malatesta a. (1942) le formazioni pleistoceniche del livornese. atti soc. tosc. sci. nat., mem., 51, pp. 145-206. malatesta a. (1948) formazioni eoceniche del distretto di kangra (punjab-india). atti soc. tosc. sc. nat., mem., 51, pp. 145-206. malatesta a. (1950) sulla grotta reale a porto azzurro (elba). riv. sc. preist., 5, pp. 90-94. malatesta a. (1951) considerazioni sugli ochtonidae fossili e viventi. boll. serv. geol. d’it., 71, pp. 121146. malatesta a. (1951) ricerche preistoriche nella valle della lima (lucca). riv. sc. preist., 6, pp. 79-83. malatesta a. (1951) osservazioni sull’estensione dei ghiacciai quaternari nella valle di kangra (himalaya esterna). boll. serv. geol. d’it., 73, pp. 63-75. malatesta a. (1952) il calabriano fra castiglioncello e rosignano. boll. serv. geol. d’it., 73, pp. 171-184. malatesta a. & martelli g. (1953) sull’origine e sull’età della porfirite di calbona (alghero). boll. serv. geol. d’it., 74, pp. 445-456. malatesta a. (1953) alcuni risultati della campagna geologica (1953). boll. serv. geol. d’it., 75, pp. 724-729. malatesta a. (1953) note di stratigrafia quaternaria. in: risultati del rilev. f° 192, alghero, sardegna. boll. serv. geol. d’it., 75, pp. 371-395. malatesta a. & torrente a. (1953) pliocene e pleistocene a caltagirone. boll. serv. geol. d’it., 75, pp. 399-411. malatesta a. (1954) fossili delle spiagge tirreniane. in: risultati del rilev. f° 192, alghero, sardegna. boll. serv. geol. d’it., 76, pp. 9-17. malatesta a. (1954) il cosiddetto campanile della necropoli nuragica di s.andrea priu (bonorva). riv. sci. preist., 9, pp. 105-113. malatesta a. (1954) primo dente di elefante fossile rinvenuto in sardegna. quaternaria, 1, pp. 97-103. malatesta a. & settepassi f. (1954) fossili delle formazioni continentali quaternarie. boll. serv. geol. d’it., 76, pp. 33-39. lipparini t., malatesta a.,nicosia m.l. & valdinucci a. (1955) pliocene e quaternario del capo milazzo in sicilia. boll. serv. geol. d’it., 77, pp. 1-26. malatesta a. & segre a.g. (1955) note illustrative della carta geologica d’italia. f.111, livorno, scala 1:100.000. min. dell’industria e del comm. servizio geologico. malatesta a. (1955) faune a cyprina islandica tra piazza armerina e mazzarino. boll. serv. geol. d’it., 77, pp. 447-454. malatesta a. (1955) contributi alla conoscenza delle faune neogeniche e quaternarie della siclia. iv: “dentilucina doderleini” d.st. nel pliocene inferiore della sicilia. boll. serv. geol. d’it., 77, pp. 455-460. alberto malatesta geologist and palaeontologist 7 malatesta a. (1955) risultati preliminari del rilevamento in sicilia e nelle isole egadi. boll. serv. geol. d’it., 76, pp. 517-521. malatesta a. & nicosia m.l. (1955) i fossili del pliocene e del pleistocene di agrigento della collezione lomi. boll. serv. geol. d’it., 77, pp. 173-180. malatesta a. (1956) conchiglie. il mediterraneo, 1 (3), p. 2. malatesta a. & motta s. (1956) notizie preliminari di geologia messinese. boll. serv. geol. d’it., 78, pp. 463-466. malatesta a. & segre a.g. (1956) considerazioni paleontologiche e sistematiche sulla turris (fusiturris) undatiruga biv. atti soc. tosc. sci. nat., 63, pp. 12-32. jacobacci a., malatesta a. & martelli (1956) – prime notizie sul nuovo rilevamento geologico dei monti peloritani. boll. serv. geol. d’it., 78, pp. 447-454. malatesta a. (1957) terreni, faune ed industrie quaternarie nell’arcipelago delle egadi. quaternaria, 4, pp. 165-190. malatesta a. (1957) on thais (polytropa) lapillus (linnè) in the pleistocene of sicily. journ. palaeont. soc. india, dn wadia jub. numb., 2, pp. 113118. malatesta a & pannuti s. (1957) giacimento preistorico di superficie presso acilia. bull. paletn. ital., n.s., 66, pp. 269-275. malatesta a. (1958) cenni sui risultati delle campagne geologiche effettuate durante l’anno 1956. (sicilia: pattiappennino meridionale: benevento). boll. serv. geol. d’it., 79, pp. 475-477. malatesta a. (1958) osservazioni sul pliocene ed il pleistocene della costa settentrionale della sicilia tra gualtieri sicaminò e gioiosa marea. boll. serv. geol. d’it., 79, pp. 291-326. malatesta a. (1959) notizie preliminari su una fauna del pleistocene siciliano. boll. serv. geol. d’it., 80, pp. 77-81. malatesta a. (1959) note di geologia e morfologia sulla valle caudina e sulla valle del f. calore. boll. serv. geol. d’it., 80, pp. 255-260. malatesta a. (1959) di un livello fossilifero attraversato dalla galleria di bomba nella valle del sangro. boll. serv. geol. d’it., 80, pp. 261-273. malatesta a. (1960) malacofauna pleistocenica di grammichele (sicilia). mem.per servire alla descrizione della carta geologica d’italia, 12, pp. 1196 malatesta a. & motta s. (1961) i terreni del pleistocene. in: “piano di studio sullo stretto di messina per il collegamento della sicilia con la calabria”. regione siciliana, 1, pp. 1-66. jacobacci a., malatesta a. & motta s. (1961) piano di studi nello stretto di messina per il collegamento della sicilia con la calabria. i. ricerche geologiche. pp. 1-66. malatesta a. (1962) mediterranean polyplacophora cenozic and recent. geol. rom., 1, pp. 145-171. malatesta a. (1962) il cane selvaggio del pleistocene della sardegna. geol. rom., 1, pp. 173-189. malatesta a. (1963) malacofauna pleistocenica di grammichele (sicilia). pt. ii, scaphopoda e bivalvia. mem.per servire alla descrizione della carta geologica d’italia, 12, pp. 197-392. malatesta a. (1964) trias fossilifero a marettimo nelle isole egadi. atti soc. tosc.sc.nat., 71, 1-15. malatesta a. (1964) fossili eocenici del territorio di briga e tenda nelle alpi marittime. geol. rom., 3, pp. 65-92. malatesta a. (1964) über einige pleistozane susswassermollusken aus mittel-italien. l. arch. moll., 93, pp. 151-162. jacobacci a., malatesta a., martelli g., stampanoni g. (1967) note illustrative della. carta geologica d’italia alla scala 1:100.000. f° 163 «lucera». min. dell’industria, del comm. e dell’artigianato servizio geologico d’italia. malatesta a., perno u. & stampanoni g. (1967) note illustrative della carta geologica d’italia. alla scala 1:100.000. f°175. cerignola. min. dell’industria e del comm. e dell’artigianato servizio geologico d’italia. dragone f., maino a., malatesta a. & segre a.g. (1967) note illustrative della c.g.i. alla scala 1:100.000. foglio 149 (cerveteri). min. dell’industria e del comm. e dell’artigianato servizio geologico d’italia. conato v., malatesta a. & valletta m. (1967) calabriano ad arctica islandica sulla costa meridionale d’abruzzo. quaternaria, 9, pp. 261-266. compagnoni b., conato v., follieri m. & malatesta a. (1968) il calabriano di scalea. quaternaria, 10, pp. 95-123. jacobacci, a. malatesta a. and martelli g. (1969) note illustrative della carta geologica d’italia. alla scala 1:100.000. foglio 121 “montepulciano”, min. dell’industria e del comm. e dell’artigianato servizio geologico d’italia. malatesta a. (1969) conchiglie di mare che si raccolgono in terra. la conchiglia, 1 (3), p.5. malatesta a. (1969) un gruppo scomparso di bivalvi: le rudiste. la conchiglia, 1 (3), p.5. malatesta a. (1970) cynotherium sardous studiati, an extinct canid from the pleistocene of sardinia. mem. ist. pal. um., 1, pp. 1-72. malatesta a. (1970) nascita della nomenclatura binomia e della classificazione. la conchiglia, 2 (9), p.5. jacobaccii a., bergomi c., centamore e., malatesta a., malferrari n., martelli g., pannuzzi l. & zattini n. (1970) note illustrative della carta geologica d’italia. alla scala 1:100.000. fogli 115 città di castello, 122 perugia, 130 orvieto. min. dell’industria e del comm. e dell’artigianato servizio geologico d’italia. malatesta a. & suriano f. (1971) avifauna pleistocenica di alghero (sardegna). boll. serv. geol. d’it., 91, pp. 149-158. malatesta a. (1971) appunti di paleontologia generale. pp. 1-106 (cicl. in prop). malatesta a. (1974) malacofauna pliocenica umbra. mem. per servire alla descrizione della carta geologica d’italia, 13, pp. 1-498. caloi l. & malatesta a. (1974) il cervo pleistocenico di sardegna. mem. ist. it. pal. um., 2, pp. 163247. ambrosetti p., arias c., bigazzi g., bonadonna f.p., de giuli c., girotti o., kukla g., iaccarino s., malatesta a., mazzanti r., radicati di brozolo f. zarlenga 8 f. & trevisan l. (1975) guide book. meeting of the inqua. pisa perugia tarquinia. march april 1975, pp. 1-35. malatesta a. (1977) the skeleton of nesolutra ichnusae sp.n., a quaternary otter discovered in sardinia. geol. rom., 16, pp. 173-209. malatesta a. (1978) on the genus cyrnaonix helbing, 1935 (mustelidae, lutrinae) and its type species. quaternaria, 20, pp. 109-116. malatesta a. ed. (1978) torre in pietra-roma. quaternaria, 20, pp. 203-577. malatesta a. (1978) la serie di torre in pietra nel quadro del pleistocene romano. quaternaria, 20, pp. 537-577. angelelli f., caloi l., malatesta a. & palombo m.r. (1978) fauna quaternaria di venosa. cenni preliminari. atti della xx riunione scientifica dell’ist.it. di preistoria e protostoria in basilicata. 16-20 ottobre 1976, pp. 133-140. malatesta a. (1980) dwarf deer and other late pleistocene fauna of the simonelli cave in crete. accademia, nazionale dei lincei, quaderno 249, pp. 1-128. conato v., esu d., malatesta a. & zarlenga f. (1980) new data on the pleistocene of rome. quaternaria, 22, pp. 131-176. gliozzi e. & malatesta a. (1980) the quaternary goat of capo figari (northeastern sardinia). geol. rom., 19, pp. 295-347. malatesta a. (1981) appunti di paleontologia dei vertebrati. pp. 1-86 (cicl. in prop.). angelelli f., gliozzi e. & malatesta a. (1982) l’encefalo di nesogoral melonii (dehaut), nemoredino quaternario della sardegna. boll. serv. geol. d’it., 103, pp. 35-52. gliozzi e. & malatesta a. (1982) a megacerine in the pleistocene of sicily. geol. rom., 21, pp. 311-395. malatesta a. & zarlenga f. (1982) nuovo giacimento con fauna ad arctica nei dintorni di roma. quad. paleont. strat. ed evol., 2, pp. 127-128. gliozzi e. & malatesta a. (1983) i molluschi del paleocene di baixa chinauanine nel bacino del rio massintonto (maputo-mozambico). geol. rom., 22, pp. 85-145. gliozzi e., malatesta a. & palombo m.r. (1984) upper pleistocene small mammals associations from is oreris area (inglesiente) sw sardinia. geol. rom., 23, pp. 121-131. malatesta a. (1985) cause e meccanismi delle variazioni di taglia e delle modificazioni strutturali nei mammiferi quaternari delle isole mediterranee. boll. soc. paleont. it., 24, pp. 195-199. malatesta a. (1985) geologia e paleobiologia dell’era glaciale. pp. 1-282 nis ed., roma. belluomini g., malatesta a., branca m. & spano (1985) aminoacid recemization dating of sardinian raised marine deposits. boll. soc. geol. it., 104, pp. 223-229. malatesta a. & zarlenga f. (1985) il quaternario di pomezia (roma) e la sua fauna marina. boll. soc. geol. it., 104, pp. 503-514. gliozzi e., malatesta a. & zarlenga f. (1985) il quaternario della pianura pontina. in: “progetto laghi costieri”. università degli studi di roma amm. prov. di latina. belluomini g., branca m., delitala l., malatesta a. & zarlenga f. (1986) isoleucine epimerization ages of some pleistocene sites near roma. human evol., 1, pp. 1-5. malatesta a. & zarlenga f. (1986) evoluzione paleogeografico-strutturale plio-pleistocenica del basso bacino romano a nord e a sud del tevere. (sintesi preliminare). atti del 73° congresso della soc. geol. it., pp. 47-50. gliozzi e., malatesta a., ventura g. & zarlenga f. (1986) ambienti e comunità in malacofaune marine del pleistocene inferiore della bassa campagna romana. atti del 73° congresso della soc. geol. it., pp. 43-46. cassoli a., corda l., lodoli c., malatesta a., molaroni m.v. & ruggeri a. (1986) il glacialismo quaternario del gruppo ocre-velino-sirente. atti del 73° congresso della soc. geol. it. pp. 335338. cassoli a., corda l., lodoli c., malatesta a., molaroni m.v. & ruggeri a. (1986) il glacialismo quaternario del gruppo ocre-velino-sirente. mem. soc. geol. it., 35, pp. 855-867. malatesta a. & zarlenga f. (1986) evoluzione paleogeografico-strutturale plio-pleistocenica del basso bacino romano a nord e a sud del tevere. mem. soc. geol. it., 35, pp. 75-85. gliozzi e., malatesta a., ventura g. & zarlenga f. (1986) ambienti e comunità in malacofaune marine del pleistocene inferiore della bassa campagna romana. mem. soc. geol. it., pp. 35, 87-97. caloi l., gliozzi e., kotsakis t., malatesta a. & palombo m.r. (1986) osservazioni sulla paleobiogeografia dei mammiferi del pleistocene italiano. hystrix, 1: pp. 7-23, roma. gliozzi e., malatesta a., palombo m.r., (1986) upper pleistocene small mammal associations in the is oreris area (iglesiente, sw sardinia). geol. rom., 23 (1984), pp. 121-129. malatesta a. & zarlenga f. (1986) cicli trasgressivi medio pleistocenici sulle coste liguri e tirreniche. geol. rom., 25, pp. 1-8. malatesta a. & zarlenga f. (1986) northern guest in the pleistocene mediterranean sea. geol. rom., 25, pp. 91-154. willemsen g.f. & malatesta a. (1987) megalenhydris barbaricina sp.nov., a new otter from sardinia. proceedings of the koninklijke nederlandse akademie van wetenschappen., 90, pp. 83-92. carboni m.g., malatesta a. & zarlenga f. (1988) il quaternario fra praja a mare e scalea (calabria settentrionale). atti 74° congr. soc. geol. it., settembre 1988, sorrento, pp. b 80-85. carboni m.g., malatesta a. & zarlenga f. (1988) il quaternario fra praja a mare e scalea (calabria settentrionale). mem. soc. geol. it., 41, pp. 645652. compagnoni b., jacobacci a., malatesta a. & valletta m. (1988) carta geologica d’italia alla scala 1:50.000. f. 373-cerveteri. serv. geol. d’it. malatesta a. & zarlenga f. (1988) evidence of middle pleistocene marine transgression along the mediterranean coast. palaeogeogr., palaeoclim., palaeoecol., 68, pp. 311-315. malatesta a. & willemsen g.f. (1988) algarolutra g.n., estabilshed for a fossil otter of the sardinia alberto malatesta geologist and palaeontologist 9 island. geol. rom., 25, pp. 285-286. caloi l., malatesta a. & palombo m.r. (1989) biogeografia della calabria meridionale durante il quaternario. atti acc. peloritana dei pericolanti, 67, pp. 261-278. gliozzi e., malatesta a., (1993) il quaternario marino e continentale del lazio. guida geologica regionale del lazio s.g.i., 5, pp. 74-77, ed be-ma, milano. gliozzi e., malatesta a., scalone e., (1993) revision of cervus elaphus siciliae pohlig, 1893, late pleistocene endemic deer of the siculomaltese district. geol. rom., 29, pp. 307-353. bono p., malatesta a. & zarlenga f. (1994) percorso 14. da velletri a san felice circeo. guida geologica regionale del lazio s.g.i., 5, pp. 322-343. malatesta a. & zarlenga f. (1994) nota aggiuntiva alla malacofauna pleistocenica della cava tacconi, nei pressi di pomezia (roma). il quaternario, 7, pp. 65-68. ms. ricevuto il 14/05/2010 testo definitivo ricevuto il 07/09/2010 ms. received: may 14, 2010 final text received: september 7, 2010 sess 1_160211.pub il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 ms. received: testo ricevuto il a potential gssp for the upper pleistocene alessandra negri 1, fabrizio antonioli 2, lorenzo angeletti 3, stefano marabini 4, giuseppe mastronuzzi 5, paolo montagna 6, andrea piva 7, daniele scarponi 4, marco taviani 3, luigi vigliotti3 & gian battista vai4  1 universita’ politecnica delle marche, ancona (centrato, arial 10) 2 enea, casaccia, roma 3 ismar cnr, bologna 4 universita’ degli studi di bologna, bologna 5 universita’ degli studi di bari, bari 6 cnrs gif sur yvette, france 7 eni san donato milanese (mi) corresponding author: a. negri <a.negri@univpm.it> abstract: negri a. et al., a potential gssp for the upper pleistocene. (it issn 0394-3356, 2011) here we present the results of an integrated stratigraphic study performed in the taranto area for the definition of the tarentian stage for the upper pleistocene riassunto: negri a. et al., un potenziale gssp per il pleistocene superiore. (it issn 0394-3356, 2011) presentiamo i risultati dello studio di una sezione localizzata nell’area di taranto potenzialmente utile per la definizione del piano tarentiano del plestocene superiore key words:chronostratigraphy quaternary, tarentian stage parole chiave: cronostratigrafia,quaternario, piano tarentiano the importance of a well established chronostratigraphy is a starting point for the correlation of the various archives used for the reconstruction of climate, regional sea level fluctuations and tectonic movements. in this frame the italian commission on stratigraphy of the sgi is seeking for a marine section suitable for defining the upper pleistocene gssp. this series has been usually identified with the tyrrhenian stage which in the wake of formalization received different meaning from stratigraphers and geomorphologits. hence, the proposal of a new upper pleistocene stage name and type area, the tarentian, made in 1994. criteria for defining the tarentian stage and selecting its gssp can be the beginning of mis 5 ( 134 ka) and the beginning of mis 1 ( 10 ka) taken for the base of the holocene. the tarentian stage contains also mis 5.5 highstand with its peak at 125 ka. upper pleistocene marine deposits of thickness exceeding 1 to 2 m are rarely exposed on land except for some mediterranean countries. italian coastal areas keep some hundreds of marine upper pleistocene sites. they are all characterized by the so called strombus bubonius senegalese tropical fauna (persististrombus latus (gmelin, 1791) (= bubonius (lamarck, 1822). they are found at different elevations from -130 to +170 m depending on the strong differential crustal mobility of the area. the best up to some 10 m thick upper pleistocene marine sections are exposed at the coast of the gulf of taranto facing the ionian sea. here, where a well exposed marine succession has been uplifted very recently, we have explored the possibility to find a suitable gssp for the upper pleistocene adopting a combined stratigraphic approach based on litho bio and magnetotsratigraphy and corroborated by paleoecological and, u-th analyses. 44 january 13, 2011 13 gennaio 2011 sess 1_160211.pub il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 holocene palaeo-geographical evolution of the sele river coastal plain (southern italy): new morpho-sedimentary data from the paestum area vincenzo amato1, pietro p.c. aucelli2, aldo cinque3, bruno d’argenio4, valentino di donato3, gerardo pappone2, paola petrosino3, carmen m. rosskopf1 & elda russo ermolli5 1dipartimento stat, università del molise, 2dipartimento disam, università parthenope, napoli 3dipartimento st, università federico ii, napoli 4iamc-cnr, napoli 4 dipartimento arbopave, università federico ii, napoli corresponding author: v. amato <vinamato@unina.it> abstract: amato v. et al., holocene palaeo-geographical evolution of the sele river coastal plain (southern italy): new morpho-sedimentary data from the paestum area. (it issn 0349-3356, 2011) the sele river plain is hosted in a graben along the tyrrhenian margin of the southern apennine chain and is formed of both displaced (early and middle pleistocene) and undisturbed (late pleistocene and holocene) sedimentary units. the strip that was accreted to the plain during the holocene high stand is characterized by beach-dune ridges whose sands interfinger –to the rearwith lagoonal and fluvio-palustrine deposits. the evolutionary trend was transgressive during the early holocene and progradational during the mid-late holocene. in this work, we present new data about the holocene evolution of the portion of the plain in front and immediately north of the poseidonia-paestum archaeological area, where the knowledge has been improved by five new cores and by many collected archaeo-bio-tephrostratigraphical data. in the first area (paestum area), due to a local rise of the ground (made of late pleistocene travertines) the holocene transgression formed cliffs, while the second area (laura area) was submerged. the tip of the travertine lobe was then cut by a sea cliff, whose correlative abrasion platform rests 7,5 m below the present s.l. the age of this stage can be inferred by the 14c dated mollusk remains (7.0 ky cal bp) of the beach deposits, found at the same depth in the laura cores. in mid holocene times the shoreline shifted seaward and a lagoonal environment – closed by the laura sand ridgewas established (fossa lupata area). age constraints for this stage are the agnano m. spina tephra (4.1 ky bp) and some archaeological remains of the vi cent. b.c. found within the upper part of the lagoonal clays. after this period, and mostly after the deposition of the 79 a.d. tephra, the shoreline shifted further seaward and an additional beach ridge formed, whereas the flat area of fossa lupata was rapidly aggraded and dried up. riassunto: amato v. et al., l’evoluzione paleogeografica olocenica della piana costiera del fiume sele (italia meridionale): nuovi dati morfo-sedimentari dall’area di paestum. (it issn 0349-3356, 2011) la piana del fiume sele, ospitata in un half-graben del margine tirrenico dell’appennino meridionale, è costituita da complessi fluvio-transizionali e costieri che appaiono sia dislocati (pleistocene inferiore e medio) che sostanzialmente indisturbati (pleistocene superiore ed olocene). i paleo-cordoni costieri del tirreniano (ois 5) decorrono a circa 3 km dalla costa attuale; una distanza pari all’ampiezza della fascia aggiuntasi alla piana durante l’olocene. tale fascia si caratterizza per la presenza di cordoni costieri le cui sabbie passano –verso montea depositi lagunari e fluvio palustri. come mostrano i dati di sottosuolo, la tendenza evolutiva generale è stata trasgressiva nella prima parte dell’olocene (con migrazione verso terra del sistema barriera-laguna) e progradazionale poi (d’argenio et al, 2010). in questo lavoro vengono presentati i principali risultati di una indagine sulla evoluzione olocenica del tratto di pianura antistante (area di paestum) ed immediatamente a n (area di laura) l’area archeologica di paestum (settore se della piana del sele). nell’area di paestum la fascia costiera olocenica, composta da più cordoni sabbiosi separati da piatte depressioni limotorbose, è meno ampia che nell’area di laura per la presenza di un dosso travertinoso che deve aver costituito un paleo-promontorio durante le fasi culminanti della trasgressione post-glaciale. al fine di ricostruire in dettaglio le locali morfo -dinamiche costiere oloceniche, sono stati eseguiti 5 nuovi carotaggi in settori strategici, individuati mediante una accurata revisione dei dati archeologici e stratigrafici preesistenti. sui livelli più significativi delle carote sono state eseguite analisi biostratigrafiche, palinologiche e tephrostratigrafiche supportate da indicazioni cronologiche fornite da datazioni 14c e da determinazioni archeologiche. i risultati conseguiti dimostrano in modo definitivo che le scarpatine rocciose che a tratti si riconoscono intorno al dosso travertinoso (ben evidente presso la porta marina di paestum) sono la parte ancora emergente di una falesia costiera che si modellò durante la trasgressione olocenica. circa la successiva fase di progradazione della linea di costa, i dati raccolti mostrano che essa avvenne con la formazione di un esteso cordone dunare (cordone di laura), posto circa 1 km più avanti della paleofalesia e recante alle spalle la depressione lagunare di fossa lupata. le analisi biostratigrafiche, supportate da reperti archeologici ascrivibili al vi sec a.c., dal del tephra di agnano m. spina (4.1 ka bp), e da datazioni assolute 14c, eseguite all’interno dei depositi limo-argillosi dei nuovi sondaggi, confermano la presenza di tale sistema morfo-sedimentario di barriera-laguna costiera per l’intervallo di tempo che va da circa 7.000 anni fa alla data di fondazione della città di poseidonia (540 a.c.). dopo questo periodo e prevalentemente dopo la deposizione dei prodotti distali dell’eruzione vesuviana del 79 d.c., la linea di costa entrò in una nuova fase di prevalente progradazione. nel contempo la depressione di fossa lupata conobbe una rapida aggrada 5 7 6 zione ad opera di depositi fluvio-palustri, riducendo fortemente il proprio areale, fino ad essere bonificata dall’uomo nel secolo scorso. key words: holocene, sea level rise, sele plain. parole chiave: olocene, risalita del livello del mare, piana sele 1. introduction the glacio-eustatic sea level rise occurred after the last glacial maximum (lgm) led to a worldwide flooding of coastal plains and controlled the evolution of marine embayments, fluvial mouths and rocky coasts.its significant deceleration in the midholocene often led to overcompensation by sediment supply and shoreline progradation. in the mediterranean area, progradation was more marked during the last 2.5 ky, when the impact of man on soils and vegetation covers increased the rates of erosion and, consequently, the solid discharge of rivers toward the coasts (amato, 2006 and references therein). this general evolutionary trend has been widely recognized by many multiproxy researches, including geomorphology, geology, palaeobiology and archaeology (pirazzoli, 1996 and references therein). similarly, it is known that the alluvial-coastal plain of the sele river was interested by the same morpho-sedimentary behavior during the holocene, with a transgressive trend during the early holocene and a progradational trend of shorelines starting from middle holocene (cinque, 2008 and references herein) the sele river plain is located along the tyrrhenian margin of the southern apennine chain and is formed of both displaced and undisturbed sedimentary units. the former are early to middle pleistocene in age, while the latter span from the last interglacial (ois 5) onwards. the fossil beach ridges of the late ois 5 run about 3 km inland from the present shoreline; a distance corresponding to the strip that was accreted to the plain during the holocene high stand. migrating also upward, the sandy barrier (including a dunal cover) reached up to 4-6 m above the present s.l. in the middle holocene (laura ridge; with shells dated between 5.3 and 3.6 ka; cinque, 2008 and references therein). the buildup of this ridge marked the beginning of a prevailingly progradational phase that included the construction of two other sand ridges (sterpina i and ii, dated to before 2.6 ky bp and around 2.0 ky bp respectively) and the filling of the back-barrier depression, initially with lagoonal pelites and then with palustrine deposits (cinque, 2008 and references therein). in the se portion of the sele plain, the late quaternary coastal evolution was affected by numerous generations of travertine deposits. recently, amato et al, (2009) have provided a detailed chronological reconstruction of the various stages of the paestum depositional system: it was active during the last interglacial (tyrrhenian) and the early holocene until about 5000 years ago, and in the historical period during the late-ancient and middle ages (v-ix century ad). in the coastal sector, in front of the archaeological area of poseidonia-paestum lippmann-provansal (1987) proposed, that a coastal lagoon had already established in the iron age (3.0 ky ago) while guy (1990), suggested that, during the classic period (2.5 ky ago), there was only a small lagoon (pond or artificially preserved and open to the sea). using geomorphological and integrated stratigraphic methods, we focused the researches on the holocene morpho-stratigraphy changes of this sector of the sele plain, in order to reconstruct the paleoenvironmental and landscape changes, and to decipher the local sea level rise history and horizontal shoreline changes. 2. new morpho-stratigraphical data the coastal strip in front of the archaeological area of paestum presents a very articulated landscape, consisting in an inner area situated at an altitude between 10 and 20 m a.s.l., some meters higher than the average level of the plain, that does not exceed 5 m a.s.l. such morphological high, slightly sloping to the sea, appears to be composed of travertine deposits, belonging to different depositional bodies (as previously described). these polyphasic depositional bodies, generated during the late quaternary, now form self-terraced bodies. landward, the hanging travertine bodies are connected to the piedmont belt of the capaccio hills and seaward to the coastal strip by a steep escarpment cut into travertine, whose remains are still visible at porta marina of paestum. this steep scarplet gently downgrades toward a depressed area (fossa lupata), situated at ca. 4 m a.s.l. behind a large sand dune ridge, which reaches ca. 6 m a.s.l. and is located about 1 km from porta marina. in the sector immediately northward, some units of the poliphased travertine lobe interfinger with barrierlagoonal systems of the hssls of ois 5. here, the holocene coastal strip is wider and, from its inner side down to the present shoreline, is constituted by a great flat depression area (2-3 m a.s.l.), connected with fossa lupata, and delimited seaward by two sandy barriers. in addition to the numerous archaeological and geoarchaeological data obtained from excavations, and to stratigraphic data derived by collected cores, five new cores (s2, s3, l1, l2 and l3) were drilled. s2 and s3 were taken, respectively, in the v. amato et al. 7 ms. received: testo ricevuto il area immediately west of the scarplet cut into the travertine of porta marina (5.5 m a.s.l.), and in the outer dune ridge, immediately behind the coastal road (2.5 m a.s.l.). l1, l2 and l3 were drilled in the area immediately north of the poseidonia-paestum archeological area, where the laura barrier-lagoon system crop out. the morpho-stratigraphic data, supported by biostratigraphic analyses, by tephra layer correlation, such as the 79 ad, the agnano monte spina (4.1 ky bp), the neapolitan yellow tuff (15ky bp), and the y3 tephra (30 ky bp), by 14c dated layers, by layers with archaeological remains, and referring the data to the known holocene morpho-sedimentary trends, allowed us to outline some important stages of the holocene palaeogeographical evolution of the se sector of the alluvial coastal plain. • the sea level low-stand of the lgm(20 ky bp) led to a strong progradation of the shoreline. therefore, the whole studied area was interested by fluvial-marshy sedimentation including the neapolitan yellow tuff and the y3 tephra. • the rapid sea level rise of the first part of the postglacial period led to a rapid submergence of the coastal plain. in the area of paestum, the transgressive trend has favored the formation of a cliff cut in travertine, now partly buried by travertine deposits of mostly medieval age. • as soon as the rate of the holocene sea level rise decreased, a rapid shoreline progradational trend started, and a barrier-lagoon coastal system formed. the 14c dating of mollusk remains from the beach deposits (7.0 ky cal bp), the presence of the agnano m. spina tephra (4.1 ky bp) and the archaeological remains of the vi cent b.c. into lagoonal deposits allowed us to hypothesize the presence of a barrier-lagoon coastal system during this period. • between the foundation of the greek-roman town of poseidonia-paestum (540 b.c.) and the 79 ad, the lagoonal area was interested by continental deposition (marsh); the shoreline prograded a few hundred meters and an additional sandy dune ridge formed seaward. • after the 79 ad and up to now, the shoreline progradational trend was emphasized and the flat depression area was interested by a strong aggradation of the ground level due to anthropogenic fills, reworked volcaniclastic deposits of the 79 ad and historical deposition of travertines. in conclusion, the archaeo-bio-tephra-chronostratigraphic data allowed us to assert that the holocene sea level rise reached -7,5 m a.s.l. at about 7.0 ky bp and -1.5 m a.s.l. at about 4.1 ky bp. these data, if compared with those about the holocene sea level rise in the mediterranean area, suggests that the paestum sector of the plain has been interested by a substantial tectonic stability. references amato v. (2006) la risposta di alcuni tipici sistemi morfodinamici della campania (italia meridionale) alle variazioni climatiche oloceniche. tesi di dottorato università “federico ii” di napoli 2006, www.fedoa.unina.it/406. 405 amato v., avagliano g., cinque a., cipriani m., di paola g., pontrandolfo a., rosskopf m. c. & santoriello a. (2009) geomorphology and geoarchaeology of the paestum area: modifications of the physical environment in historical times. mediterranee, 112, 129-135. cinque a. (2008) note illustrative del foglio geologico al 50.000 foce sele. servizio geologico nazionale d’argenio b., amato v., anzalone e.,. aucelli p.p.c, cesarano m., cinque a, da prato s., di paola g., ferraro l., pappone g., petrosino p., rosskopf c. m., russo ermolli e. (in press) holocene palaeo-geographical evolution of the sele river alluvial-coastal plain: new morphosedimentary data from poseidonia-paestum area. volume mare cnr, in stampa guy m. (1990) le rivage marittime et la «lagune» de poseidonia-paestum. in: albore livadie c. & widemann f. (eds.). pact, 25, 257-270. lippman-provansal m. (1987) l’apennin campanien meridional (italie). etude geomorphologique. these de doctorat d’etat. univ. aixmarseille. pirazzoli p.a. (1996) sea-level changes. the last 20.000 years. john wiley & sons, chinchester, inghilterra, 211. holocene palaeo-geographical evolution of the sele ... january 15, 2011 15 gennaio 2011 amq30(1) 2 toniato 2.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 30 (1), 2017, 11 23 revised bison skull from the salita di oriolo quarry near faenza, “sabbie gialle”, pleistocene, northern apennines giulia toniato 1, stefano marabini 2, benedetto sala 1, gian battista vai 2 1 museo di paleontologia e preistoria, università di ferrara, italy 2 museo geologico giovanni capellini, dip bigea, alma mater studiorum, università di bologna, italy corresponding author: s. marabini <stemarabini@libero.it> abstract: improvements in the knowledge of middle to late pleistocene terrestrial stratigraphy in the romagna and emilia apennine foothills and new studies on the underlying marine yellow sand deposits have led to reconsider the taxonomy of a fossil bison neurocranium found in the “sabbie gialle” layers of the salita di oriolo quarry, near faenza in the late 1980s. the skull fragment, erroneously associated in the past with a southern mammoth (mammuthus meridionalis) skull found in the same large quarry some distance away from it, was identified as bison aff. schoetensacki. reanalysis of morphometric traits and comparison with other fossil material questions this interpretation and suggests a re-positioning of the oriolo bison among the primitive bison (eobison) forms of the late villafranchian, before the end of the early pleistocene. to test the consistency of the new assignment, an updated review of all available regional and local stratigraphic data is here presented. original and new field data are focused in view of a more precise dating of the top layers of the marine blue clay (argille azzurre) fm underlying the “sabbie gialle” (yellow sand) and of a closer correlation of the different cyclic sand bodies. the outcome is that the bison skull was dug about 25 m below the mammuthus meridionalis, and both mammals were buried into different depositional cycles separated by unconformities. while the mammoth remain was emplaced sometimes after the matuyama/brunhes reversal and may therefore be assigned to the middle pleistocene, the bison is definitely older, and might actually be correlated with a late early pleistocene sicilian age not far from the jaramillo subchron, which is the present target of field research. keywords: late lower and middle pleistocene, marine biostratigraphy, large mammals, cyclostratigraphy, magnetostratigraphy. 1. introduction the classic lithostratigraphy of the plio-pleistocene foothills of the northern apennines, dating back to leonardo da vinci (1452-1519), jacopo bartolomeo beccari (1682-1766), giambattista brocchi (1772-1826), and giuseppe scarabelli (1820-1905) to whom we owe the traditional marine formation names of argille azzurre (blue clay),” sabbie gialle” (yellow sand), and the recognition of terraced alluvial deposits (see also selli, 1949a, 1949b, 1962; ruggieri, 1944; ruggieri & selli, 1949-1950, azzaroli & berzi, 1970, vai, 1988), has been articulated and improved in the last century with the addition of a sequential approach, which resulted crucial in understanding the marginal environment (“sabbie gialle”) and even more the continental (terraced) deposits. in spite of this, some problems remain unresolved. this paper proposes an updated taxonomic and chronological position of the bison skull from the “sabbie gialle” of the salita di oriolo quarry (masini et al., 1995), and contributes to improving the stratigraphic framework of the imola sands (amorosi et al., 1998a, 1998b), as well as discussing some results recently published in a paper by muttoni et al. (2011). 2. previous studies and stratigraphy of “sabbie gialle” in the imola-faenza foothills an increasing use of a sequential approach (ricci lucchi, 1982; vai 1984, 1988; marabini et al., 1987a, 1987b; farabegoli, 1985; farabegoli & onorevoli, 1991; farabegoli et al., 1999; marabini & vai, 1995; marabini et al., 1996; amorosi et al., 1998a, 1998b; capozzi & picotti, 2003) was postulated also by the tectonic pulses (both compressional and extensional) which have affected at different times the various parts of the foothills due to the outward migration of the apennine chain (castellarin & vai, 1986, vai & castellarin, 1992, picotti & pazzaglia, 2008, picotti et al., 2009). in this frame, ricci lucchi (1982) first introduced a sequential framework separating marine (qm) from mainly continental (qc) sequences (fig. 1). later on, vai (1984, 1988) and marabini et al. (1987a, 1987b) emphasized the basic difference between regressive yellow sand (conformably closing the gradual shallowing of the blue clay depositional environment) and transgressive yellow sand bodies (unconformably representing deposits of monoor polycyclic climatically-driven temporary marine ingressions over the uplifting foothill area as already stated by selli, 1949a, 1949b and ruggieri, 1944). an additional distinction was made between yellow sand bodies, marked by cold biotas alternating within the upper blue clay (aa) fm, and yellow sand bodies with warm subtropical biotas characteristic of the transgressive yellow sand cluster (marabini et al. 1996). two different types of midrank cyclicity were singled out in the plio-pleistocene deposits of the apennine foothills separating thrust-top and foreland basins. the shallower thrust-top front-apennine basins, characterized by three main recurrent arctica islandica horizons (fig. 1), are bio-climatically controlled and punctuated by cold peaks within the santernian, emilian, 12 toniato g. et al. and sicilian mediterranean regional substages (with apparent 400 ka eccentricity forcing at about mis 64, 38 -36, 22).the first arctica horizon is developed in clayey facies, part of the second and the third in sandy facies, indicating gradual basin shallowing and infill (blue clay regression). another type of cyclicity is suggested by four main marine sandy bodies intercalated into and topping the blue clay (aa) fm (fig. 1). they are roughly dated around 1.3-1.2 (mis 38-36), 1.05 (mis 30), 0.88 (mis 22), and 0.75 (mis 19-17) (vai 1995, p. 173; marabini et al. 1996, p. 272). the first and third overlap with arctica islandica horizons, consistently with climatically-induced marginal sea-level dropping in a frame of dominating 40 ka obliquity forcing (fig. 1). the fourth instead is provided with warm flora and fauna, suggesting deposition during one or two high sea-level stands of 100 ka eccentricity forcing. the sand bodies appear roughly punctuated by c. 200 and 100 ka recurrence time and were involved in terminal outer apennine folding phases (vai, 1995, p. 173; marabini et al., 1996, p. 272) (fig. 1). both types of lithologic and faunal cyclicity are much better developed in the coeval marginal sicily basins (catalano et al. 1997). the deeper foreland basin presents less or no sand bodies inside the blue clay (aa) fm. a lithostratigraphic formalization (imola sands) and subdivision, required for official geological mapping purposes and suitable for the castel s. pietro to imola area and the related southern po plain core 239-s1, was established by the emilia-romagna geological survey (amorosi et al., 1998a, 1998b; benini et al., 2009). this lithostratigraphy is intimately tied in to a simplified sequence frame. however, both lithoand sequencestratigraphic frames are not straightforwardly correlated outside the imola type area, even in the close wellstudied faenza area, and increasing correlation uncertainty is found outside the foredeep-foreland basin in the nearby thrust-top basins (see also amorosi et al. 1998b, fig. 6). basic tools for dating the “sabbie gialle” have relied upon large mammals and leaves, foraminifera and nannoflora, and palaeomagnetic inversions. continental faunas and leaves that flooded into the coastal sands prompted a villafranchian (equivalent to calabrian) age (scarabelli 1849, 1881) which basically continues into the present age assignment (azzaroli & berzi, 1970, masini et al., 1995, 2013; masini & sala, 2007, ferretti, 1999). in spite of warnings about uncertainty in collecting sites and strata and repeated suggestions that fossils at hand from both past centuries could derive from quite different horizons and rock bodies (vai, 1984, 1988; marabini et al., 1996; torre et al., 1996), vertebrate palaeontologists have steadily assumed the occurrence of a unique yellow sand oriolo fauna of dubious and quite debated late villafranchian or possibly early galerian age (masini et al., 1995) (fig. 1). foraminifera and nannoflora are useful in dating the top of the blue clay (aa) fm and clayey marine fig. 1 lithostratigraphic correlation on a sequential frame tied to geological time, romagna apennine foothills. 13 revised bison skull from the salita di oriolo quarry near faenza, ... intercalations within the overlying transitional sand bodies. unlike biostratigraphic dating of the 1980s, at the end of the century it became clear that, as in the marche area, also in the po plain-adriatic foreland basin continuous blue clay sedimentation reached the late sicilian, above the jaramillo chron, thus placing the imola sands (and other “sabbie gialle”) already within the middle pleistocene (marabini et al., 1996, p. 272; amorosi et al.,1998b, figs 1, 17). reliable magnetostratigraphic sections of reasonable length have been published only by marabini et al., (1996), muttoni et al., (2011) both for the imola-faenza foreland basin and by gunderson et al. (2014) for the front-apennine thrust-top basin in the western part of the northern apennine foothills, beyond the po plain deep core 239-s1 also studied by muttoni et al. (2011). this is mirrored by the lesser thickness and shallower facies of the blue clay fm (aa) in the thrust-top basins and by earlier regression and basin infill, when compared with the imola-faenza basin. an older (~ 100 ka) magnetostratigraphic age of the sabbie di imola in gunderson et al. (2014, fig. 12) vs muttoni et al. (2011, fig. 2) was expected based on the same earlier regression in the western foothills. however, this raises a problem for both lithostratigraphic and chronological correlations. the last two paragraphs above may suggest that the imola sands can be diachronous, as can be expected for any lithostratigraphic unit. but also that not all marine yellow sand bodies nearby must have the same age (and pertain to the same sequence/cycle of the imola sands). only independent and integrated dating tools along with complete and articulated sections can provide reliable answers as to the age of individual sand bodies. within this approach, we try to investigate the stratigraphic significance of the bison skull from salita di oriolo quarry, which was found detached from the remaining skeletal bones and transported by a flood into the marine littoral environment. 3. new field data on some “sabbie gialle” sections s of faenza we examined three quite long “sabbie gialle” sections s of the city of faenza, the two best exposed and well-studied in the past decades, salita di oriolo quarry (marabini et al., 1987a, 1987b; vai, 1988, marabini et al., 1996) and monte coralli trench (not yet published except for some information in amorosi et al. (1998a, 1998b) and vaiani (2000) and unfortunately too superficial to provide magnetostratigraphic response) (fig. 2), and a new unstudied section from the falcona quarry, a presently abandoned quarry with well-preserved walls that could be preserved as geosite with good potential also for further studies. all three sections are strictly part of the same structural-stratigraphic domain, the imolafaenza foreland basin. all are composed by two dominantly sandy marine cycles bounded in outcrop by unconformity surfaces. notice that “two thick sandy layers separated by a muddy interval” were emphasized as the “milazzian” basinward equivalents of the “sabbie gialle” in the po fig. 2 chronological correlation of the salita di oriolo and m. coralli sections in the faenza area. fig. 3 the skull of the salita di oriolo bison in dorsal (a), nuchal (b) and lateral (c) views (maximum width 63 cm). 14 toniato g. et al. plain subsurface studied by selli (1949) in many boreholes. taken together, the two cycles unconformably overlay regressive sandy pelites and mud at the top of the more tectonically deformed blue clay (aa) fm, and are in turn overlain by middle pleistocene mainly pelitic partly pedogenic terrestrial deposits. the two cycles, though more or less yellow and sandy, exhibit common differences in the three sections that are related to lithology, and both lithoand biofacies. the lower (i) cycle (fig. 2) contains some lenticular gravel lags and many thin muddy beds intercalated inside the sand, suggesting alternation of littoral and lagoonal/bay environment with relevant fluvial activity, as indicated also by some layers rich in well-preserved diverse floated leaves accumulation (martinetto & sami, 2001). large mammal fragments are present with juvenile rhinoceros jawbones. the upper (ii) cycle (fig. 2) is more monotonously dominated by medium to coarse well-sorted littoral sand, suggesting a more stable and wider foreshore environment and a dryer climate. if we assume that the two “sabbie gialle” cycles have, at least partly, an orbital climatic forcing (farabegoli & onorevoli, 1991), their individual duration might overlap with one or two obliquity 40 ka intervals (especially the lower) or an eccentricity 100 ka interval (especially the upper cycle) including the erosional-depositional time gap. the salita di oriolo section (fig. 2) is the only out of the three that has provided reliable magnetostratigraphic results (all samples of the other two proved to be remagnetized). as a result, the i cycle is dominantly magnetically reversed and the ii cycle is magnetically normal. according to marabini et al. (1996) top samples of the blue clay (aa) fm and the lower one of the first “sabbie gialle” cycle are reversed. one single normal sample follows (csa 3), which in turn is overlain by a reversed interval up to near the top of the first “sabbie gialle” cycle (csa 4 to 13). the last sample of the lower (i) cycle and the first of the upper (ii) cycle instead are normal. these data have been discussed in detail by marabini et al. (1996, p. 267-270). the normal polarity interval at the top of the cycle (nos. 15, 16) should represent the beginning of the brunhes chron (0.781 ma). in this case, the tiny wiggle (no. 3) could reflect the closest normal event recognized in the matuyama chron, cryptochron kamitsura (0.85, champion et al., 1988; 0.90, coe et al., 2004). worthy to notice, two different magnetostratigraphic campaign (1987 and 1993) have shown a reverse to normal polarity pattern in the same stratigraphic position of sample no. 3, about half a metre beneath the unconformity surface separating the two cycles. alternatively, the no. 3 normal polarity interval is too short to be taken as an evidence for the jaramillo subchron (1.072 0.989). the jaramillo subchrone has been detected in the qm1 member of the aa fm in section a by muttoni et al. (2011, fig. 2) not far from salita di oriolo quarry. it consistently contains nannofossils of “the late early pleistocene part of zone nn 19 (~ 1.02 0.61 ma). however, this small muddy sandy section is interrupted before reaching the “sabbie gialle”. the monte coralli section (fig. 2), some 10 km w of the salita di oriolo section and no longer exposed, is divided into four units by three main unconformity surfaces, all marking minor upward decrease in dip, especially the first and the third ones. the first unit exhibits a transition from massive silty clay (blue clay fm) to finely bedded silty-sandy clay rich in gastropods (mainly turritella layers) and bivalves. the “sabbie gialle” lower (i) cycle contains medium to fine grained foreshore sand with thin clayey to pelitic alternations. the few basal gravel lags are characterized by black-chert pebbles. about 5° dip decrease occurs at the transition to the overlying coastal, coarse-grained “sabbie gialle” upper (ii) cycle, whose basal gravel lags contain common redchert pebbles. the “sabbie gialle” cycle i is much thicker in this section than in the salita di oriolo section, but cycle ii is correspondingly less, giving to the “sabbie gialle” a total thickness of about 48 m. the terrestrial sandy loam topping the “sabbie gialle” is distinctly pedogenic with black mn nodules pervasively developed beneath the present-day land soil (fig. 2). the falcona quarry section, quite close to the m. coralli one, has the great advantage of duplicating most of the features of the monte coralli section, and also represents a well-exposed potential “sabbie gialle” geosite. above the two “sabbie gialle” cycles, the following units were preliminary observed: fluvial deposits of the olmatello fm; heavily pedogenic alluvial plain deposits rich in gilgai periglacial calcic palaeosols (marabini et al. 1987); and possibly late pleistocene alluvial plain deposits with reddish palaeosols (rubinato et al., 2013). these units can be traced physically down to the terrestrial deposits of the alluvial fan belt in the faenza sector of the eastern po plain extensively excavated by pipelines, quarries and wells in the last decades. more generally, the different yellow sand bodies are variously involved in regional tectonics as shown in relevant changes in both thickness and facies sequence (castellarin & vai, 1986, vai, 1989, vai & castellarin, 1993). both “sabbie gialle” cycles in the imola-faenza foreland basin show modest angular unconformity at the base, consistent with vertical uplift tectonics and likely faster uplift rate after the second sandy cycle (fig. 2). earlier sand bodies within the upper part of the aa fm have been hit by the latest early pleistocene (sensu gts 2002) tectonic phase (fig. 1), as shown for the faenza foothills (by the tombe-persolino minor anticline in the rio janna and monte piano area (marabini et al., 1996), and more prominently in the s. mamante section with bed dips over 45° (farabegoli & onorevoli, 1991, farabegoli et al., 1997) not far away from the montoneforlì fault zone. accurate dating of the sand bodies and encasing mudstones is critical to unravel the age of transition from folding (usually occurring still in subacqueous conditions) to uplift (leading to stable emersion) for the different pleistocene basins of the emilia-romagna foothills, and the related yellow sand bodies. 4. the salita di oriolo bison skull the neurocranium, preserved at the civic natural history museum of faenza, was recovered in 1989 by m. diversi and m. sami at the salita di oriolo quarry, near faenza (marabini et al., 1987), one year after the discovery of the mammoth l at the same site. 15 revised bison skull from the salita di oriolo quarry near faenza, ... the fossil land mammals of oriolo all flooded into marine waters were studied in the 1990’s, when the museum’s paleontological collection was completely revised. back then the neurocranium was identified as bison aff. schoetensacki with more primitive features than bison schoetensacki from isernia la pineta (masini et al., 1995). however, recent geological researches on quaternary yellow sands have brought about the need of reconsidering this interpretation by re-examining the fossil bison (fig. 3). 4.1. description and measurements (tab. 1) the bison find from salita di oriolo consists only of the neurocranium. the skull fragment is partially preserved; the left side is slightly more damaged than the right. the horn cores are rather short with a somewhat dorso-ventrally compressed cross section and are lightly furrowed longitudinally. directed laterally and posteriorly at the base, they then bend slightly downwards in ventral direction and curve finally upwards, only to terminate with a rounded tip. this detail can be clearly observed from the right horn core, as the left horn core tip is missing. the frontal bone is quite flat and broken in the orbital region. only the upper margin of the right orbit is preserved revealing rather tubular shaped orbits. the frontal suture is partially fused and extends from the parietal roof down to the level of the supraorbital sulcus. the partial fusion of the frontal suture along with the well-developed horn cores indicate that the specimen was most likely a young-adult. in aboral view, the parietal roof shows a triangular protrusion which culminates in a highly prominent infra temporal bridge. the parietal and temporal crests form a strongly acute angle. the occiput has a trapezoidal, though incomplete, profile. the left condyle is slightly damaged and the left mastoid process as well as both paroccipital processes are missing. 4.2. mammal taxonomy, biostratigraphy, evolution and dispersal into the italian peninsula given that the oriolo specimen likely belonged to a young-adult, the relatively small size of the neurocranium sets it apart from bison menneri, which, according to sher (1997), is characterized by a very large body size. though the discovery of a complete skull of b. menneri has been reported from the site of untermassfeld (kahlke, 2009), no measurements are yet available for comparison; however, the picture of the cranium published by kahlke (2009) seems to display evolved features commonly found in the subgenus bison. likewise, comparison with the cranial cast of the taubach bison priscus and others fragmented ls from settepolesini di bondeno, housed at the ‘piero leonardi’ palaeontological museum of the university of ferrara, confirms the more primitive origin of the oriolo bison. in fact, the b. priscus skull appears much larger and heavier built and differs from the oriolo specimen in that the horn cores are sub-circular and curve readily upwards and the occipit has a rounded arch-like profile as well as a more drawn-back position of the frontal bone. unfortunately, biometric measurements had to be taken principally on horn cores, as most of the comtable 1 (1) least distance between the horn core tips, (2) greatest tangential distance between the outer curves of the horn cores, (3) length of the horn core upper side, (4) length of horn core lower side, (5) taut length (chord) of the horn core, (6) horn core basal circumference, (7) least (dorso-basal) diameter of the horn core base, (8) least (oro-aboral) diameter of the horn core base, (9) narrowness index of the horn core base, 7÷8 x 100, (10) greatest breadth of the occipital condyles, (11) height of the foramen magnum. 16 toniato g. et al. parative material was poorly preserved and lacked of substantial cranial portions. though biometry proved difficult and the results were meagre, it seems evident that the size range of the oriolo neurocranium does not overlap with that of any other species. this is consistent with the results of morphological comparison. considerable differences separate the oriolo bison from bison voigtstedtensis and bison schoetensacki. these principally concern the occipital region, which is wider and more compressed, almost sub-circular, in both b. voigtstedtensis and b. schoetensacki, and the horn cores, which are shorter and directed obliquely backwards in b. voigtstedtensis displaying an array of different morphological characters, being more swollen at the base, less curved and tapering quickly upwards. by contrast, the horn cores of the oriolo bison form an angle of approximately 90 degrees with the frontal plane and curve outwards and slightly downwards before pointing upwards, resembling quite closely those of bison (eobison) tamanensis, especially in the marked dorso-ventral flatness of the base. other striking similarities are to be noted with the subgenus bison (eobison), in particular the deep infratemporal fossae and high occiput. these two features are present in bison (eobison) palaeosinensis(teilhard de chardin & piveteau, 1930) and in the younger bison (eobison) degiulii masini 1989. though, in the latter the constriction between the occipital region and the parieto -frontals is narrower and the occipital region is smaller (masini et al., 2013). direct comparison with the holotype of bison (eobison) degiulii masini 1989, temporarily preserved at the natural science department of the university of firenze, enabled these observations. as opposed to b. (eobison) degiulii, the oriolo specimen also shows a less swollen forehead and a broader occipital region. moreover, in b. (eobison) degiulii the infratemporal fossae are narrower and more elliptical. thus, these features of the oriolo bison seem to indicate a younger age than that of b. (eobison) degiulii of the pirro fu, which is ascribable to the late villafranchian, before the end of the early pleistocene (fig. 1). the genus bison makes its appearance in the italian peninsula during the late early pleistocene, late villafranchian, with bison (eobison) degiulii, first recorded in the karstic fissure fillings of pirro nord, at the western border of the gargano peninsula (de giuli et al., 1986). this species occurs also in the italian fossil record of the late villafranchian (sensu gliozzi et al., 1997, masini & sala, 2007) in various areas, such as the mugello and upper valdarno basins and at capena, near rome (masini, 1989). the use of the subgenus eobison was proposed by flerov (1975, 1979), who decided to group together, on the basis of fossil evidence, all the small lightly built primitive bison forms of the early pleistocene. these include several species, like bison tamanensis vereshchagin, 1957 (taman peninsula, russia), bison palaeosinensis teilhard & pivetau, 1930 (nihowan, china), bison sivalensis lydekker, 1876 (siwalik, pakistan), bison degiulii masini 1989 (pirro nord, italy) and the bison sp. of venta micena (spain). according to bukhsianidze (2005), the remains of dmanisibos georgicus vekua 1995, renamed bison (eobison) georgicus, represent the oldest known bison record in europe, suggesting that the genus originated from leptobos as far back as the middle to late villafranchian transition, but masini et al. (2013) prefer to take this classification cautiously. other bison remains, assigned to the subgenus bison (eobison) (moyà-solà, 1987), were unearthed in the iberian peninsula, at the site of venta micena, which, according to recent comparative studies based on the faunal assemblage (martínez-navarro et al., 2011), could be slightly younger than dmanisi with an estimated age around 1.5-1.6 ma. however, the scantiness and poor preservation of these remains do not allow a secure classification. the earliest representative of the true bison in europe (the subgenus bison) is bison menneri, which is well-attested in the fossil-rich epi-villafranchian (early galerian for the italian biochronology) fluvial sediments of untermassfeld. its large and long-legged structure, probably an adaptation to woodland habitats (sher, 1997), makes it the biggest known european fossil bison. during the middle pleistocene, new bison forms enter the italian fossil record. bison schoetensacki, is attested in the fossiliferous breccia of slivia (ambrosetti et al., 1979) and is believed to belong to the same lineage of bison schoetensacki voigtstedtensis (fischer, 1965), though flerov (1975) considers it a distinct species. the progressive climatic decline and the arrival of the steppe bison, bison priscus, during the late galerian, determined the extinction of b. schoetensacki from the italian peninsula. in this framework, the peculiar mixture of bisontine characters of the oriolo neurocranium makes it a unique find within the italian early pleistocene fossil record. indeed, biometrical and morphological comparison with other cranial remains of early and middle pleistocene bison species does not allow definitive species identification, but accounts for important evolutionary changes in morphology. the trapezoidal profile of the occipit and the narrow constriction between the occipital bone and the parietal roof recall primitive features, similar to those of bison (eobison) degiulii, while the marked flatness of the horn cores, regarded as a distinctive character among early bison forms, resembles that of bison tamanensis. the latter is believed to be the oldest european bison, that appeared in eastern europe at the end of the villafranchian (flerov, 1979). yet, in her recent work, vislobokova (2008) correlates the tamanian faunal assemblage with the early galerian of western europe, specifically with the colle curti and untermassfeld local faunal assemblages, assigning the tamanian bison to the subgenus bison. whatever the opinion of the various authors on the subgenus of the tamanian bison, the morphological features of the oriolo specimen are comparable to those exhibited by the bison (eobison) fossil species of the late villafranchian. yet, the high occipital region and in particular the broader infra-temporal bridge of the oriolo neurocranium are probably advanced characters that indicate a younger age than that of b. (eobison) degiulii. in conclusion, revision of the taxonomic classifica 17 revised bison skull from the salita di oriolo quarry near faenza, ... tion of the bison neurocranium of oriolo adds new elements to our knowledge of the early bison forms that inhabited the italian peninsula. biometrical and morphological comparisons suggest a strong affinity with bison (eobison) fossil species, that are to be observed in the marked flatness of the horn cores near the base, the trapezoidal profile of the occipital region, the deep infra-temporal fossae and the notably constricted infra-temporal bridge. however, certain morphological features such as the high occipital region and broader infra-temporal bridge appear to be more evolved than in b. (eobison) degiulii, implying an age younger than that of the pirro fu, that falls nonetheless within the late villafranchian upper boundary (fig. 1). it is hard to admit the coeval presence of two bisons of different subgenera in northern italy and central europe given that the faunal composition in northeastern italy throughout the whole quaternary comprises species of central european provenience, in opposition to those of the ligurian-tyrrhenian versant and of southern italy. thus, the oriolo bison, which for its morphology is assigned to the eobison subgenus, should be older than bison menneri from untermassfeld, which belongs to the subgenus bison and can be roughly correlated with mis 31. 5. general stratigraphic discussion the new taxonomic assignment of the salita di oriolo skull to bison (eobison) sp. as opposed to its previous identification as bison aff. schoetensacki (masini, 1989, masini et al., 1995), implies an age of the lower “sabbie gialle” cycle (from which it was supposed to come from till now by many authors) possibly older than previously thought. this applies if the large mammal biochronology of central and northern europe, as presently known, may be assumed to be reliable also for southern europe. to correctly answer this question (1) the sampling position of the bison in the salita section must be clarified, and (2) an integrated critical review of the most relevant dating sources of deposits in the imola-faenza “sabbie gialle” basin needs to be performed. at the end of quarrying activities in the mid-1990s the salita di oriolo quarry was buried under tens of m of residual detritus, except for a minor lateral wall of sand and mudstone still exposed up to 2 to 3 m of thickness in the deepest (and stratigraphically oldest) westernmost part of the abandoned quarry, where a small farm lake was excavated. what is left today of these beds was sampled recently by muttoni et al. (2011, fig. 2, section d) and proved to pertain to a reverse palaeomagnetic interval, but was mistakenly placed by these researchers on top of the littoral “yellow sand” containing mammuthus meridionalis according to marabini et al. (1996, fig. 4). to restore a less fanciful and more reliable stratigraphy of the salita section, we have reviewed all our original field data from 1987 to 1993 to better constrain the sampling position of the large mammals (masini, 1989, masini et al., 1995, ferretti, 1999). the updated stratigraphic column of the salita di fig. 4 the westernmost part of salita di oriolo quarry in 1988 (photo by m. sami). white star (top right) indicates the projected stratigraphic position of the elephas (mammuthus) meridionalis skull found in the eastern part of the quarry; geologists are extracting remains of a juvenile rhinoceros from the sand; the digging place of the bison skull is the whitish outcrop just behind the red van. see fig. 2 for the relative stratigraphic position of the large mammal bones. 18 toniato g. et al. fig. 5 western end of the salita di oriolo quarry in 1987 (photo by g.b. vai). main unconformities separating the two marine “sabbie gialle” cycles, and the gilgai rich terrestrial deposits on top are shown. again, white star (top right) indicates the projected stratigraphic position of the elephas (mammuthus) meridionalis skull found in the eastern part of the quarry. fig. 6 digging the elephas (mammuthus) meridionalis skull at the western end of salita di oriolo quarry in 1987 (photo by g.b. vai). an umbrella and a white star indicate the digging and stratigraphic place of the elephas near the top of “sabbie gialle” cycle ii, at an altitude equivalent to the nearby country home roof (about 110 m a.s.l.). 19 revised bison skull from the salita di oriolo quarry near faenza, ... oriolo quarry (fig. 2) basically repeats descriptions and figures given by marabini et al., 1987a, 1987b; vai, 1988, marabini et al., 1996. new features are: (1) the downward extension of the column to incorporate data from an exploration trench of 1988; (2) the revised sampling position of the bison skull in the stratigraphically lowermost trench of the quarry, possibly in the deepest sandy body available to exploitation; it follows that the bison was emplaced at the top of the argille azzurre fm; (3) the replacement of the bison, drawn in wrong position in the column of marabini et al., 1996 (fig. 4), with a juvenile rhinoceros’ jawbone (found by amateurs who mistakenly held that it had been excavated at about the same level of the bison). slides taken in 1988 clearly show the sampling place of bison and rhinoceros in the western part of the quarry (fig. 4), and the sandy layer yielding the mammuthus skull at about 150 metres to the e (figs. 5, 6, 7, 8); (4) the two unconformities separating the lower regressive sands (“sabbie gialle” i cycle) from the upper transgressive littoral sands (“sabbie gialle” ii cycle), and in turn these “sabbie gialle” from the uppermost terrestrial deposits are clearly though slightly angular (especially the upper one) (fig. 3, 5); (5) the terrestrial deposits on top of the salita di oriolo section are now better correlated to the periglacial gilgai deposits (suoli a cuspidi e depressioni in marabini et al. 1987a, p. 33) (fig. 5, 7) rather than to the olmatello fm (vai, 1984, marabini et al., 1996), which instead is probably present on top of the falcona section. according to amorosi et al. (1998a, p. 86) and vaiani (2000), clays and silts of the uppermost argille azzurre (aa) fm based on strontium isotope stratigraphy are associated with a latest early pleistocene (or sicilian) age (qm1 marine sequence); the following transitional to marine (qm2) sequence has an earliest middle pleistocene (or ‘ionian’) age (fig. 1). their biostratigraphic analyses, though consistent with the above dating, have not provided marker fossils of closer resolution. however, a top sicilian age for the uppermost aa fm in the faenza sections is supported by three peaks of “northern guests” in the romagna apennines (marabini et al., 1996, p. 271; vai, 1995, p. 173) which correlate with the three northern mollusc migrations in sicily (raffi 1986). note, however, the quite different ages given by various authors to the top of the sicilian substage (see f.e. amorosi et al., 1998b, fig. 4), waiting for a formal definition of the ‘ionian’ gssp (fig. 1). even more important are the new biostratigraphic data in muttoni et al., 2011 (tab. 1), which report gephyrocapsa sp. 3 from their lower c section (that is correlated with the imo 1 member of the imola sands) suggesting deposition during late early-middle pleistocene part of zone nn19 (about 1.02-0.61 ma) that is latest sicilian to early ‘ionian’. it should be pointed out that all such isotopic and faunal dating elements derive from clayey intercalations in pure muddy or partly sandy aa fm that always fig. 7 tracing the salita di oriolo section from east to west across the quarry in 1987 (photo by g.b. vai). two main unconfomities are shown. the lower separates the marine “sabbie gialle” ii cycle heavily rubefacted on top and gently dipping 9°-10° to ne from the overlying almost flat terrestrial gilgai-rich deposits, in turn deeply incised by late pleistocene fluvial deposits (upper unconformity). lighter coloured layer on top is a detrital nappe artefact. 20 toniato g. et al. underlie our “sabbie gialle” first sandy cycle, except for section c which indeed could perhaps overlap our first sandy cycle. to sum up, revised original field data definitely show that the mammuthus skull of the salita di oriolo quarry was excavated from sands lying stratigraphically about 25 m higher than the revised bison l and some 150 m east of it (fig. 8). new stratigraphic evidence more firmly supports an early middle pleistocene age of the “sabbie gialle” cycle ii in the faenza foothills yielding a mammuthus meridionalis skull. the underlying “sabbie gialle” cycle i is best correlated with the upper part of the matuyama reversed chron, most probably above the jaramillo subchron. as the layers containing the bison sand body have resulted also to be reversed (marabini et al. 1996, muttoni et al., 2011), it follows that the skull might actually correlate with an early pleistocene sicilian age slightly younger or slightly older than the jaramillo subchron. to clarify this uncertainty further investigations are advocated for detecting the jaramillo subchron in the thick, better exposed faenza sections, showing transition from blue clay (argille azzurre) fm to yellow sand bodies, as the falcona and equivalent sections. acknowledgements we are indebted to marco sami (museo di scienze naturali faenza) for providing a colour slide of quarrying operation in 1988, and to the brothers battista and roberto geminiani for technical assistance in the field work. references ambrosetti, p., bartolomei, g., de giuli, c., ficcarelli, g., torre, d. 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(2011) first dated human occupation of italy at 0,85 ma during the late early pleistocene climate transition. earth planetary science letters, 307, 241252. moyà-solà s. (1987) los bóvidos (artiodactyla, mammalia) del yacimiento del pleistocenoinferior de venta micena (orce, granada, españa). paleontologia i evolució, memoria especial, 1, 181-236. 22 toniato g. et al. ms. received: july 5, 2016 final text received: december 5, 2016 picotti v., pazzaglia f.j. (2008) a new active tectonic model for the construction of the northern apennines mountain front near bologna (italy). journal of geophysical research 113, b08412. doi: 101029/2007jb005307. picotti v., ponza a., pazzaglia f.j. (2009) topographic expression of active faults in the foothills of the northern apennines. tectonophysics 474, 285 -294. raffi s. (1986) the significance of marine boreal molluscs in the early pleistocene faunas of the mediterranean area. palaeogeography palaeoclimatology palaeoecology 52, 3-4, 267-289. doi: 10.1016/0031-0182(86)90051-9 ricci lucchi f., colalongo m.l., cremonini g., gasperi g., iaccarino s., papani g., raffi i., rio d. (1982) evoluzione sedimentaria e paleogeografica del margine appenninico. in: cremonini g., ricci lucchi f. (cur), guida alla geologia del margine appenninico-padano. guide geologiche regionali società geologica italiana, bologna, 17-46. rubinato g., sami m., fanti f., marabini s., sala b., vai g.b. (2013) terrestrial vertebrates in mis 6 to mis 5 deposits of the zannona quarry (faenza, italy). alpine and mediterranean quaternary, 26, 55-63. ruggieri g., (1944) il calabriano e il siciliano nella valle del santerno. giornale geologia, 2, 17 (1943 -1944), 95-113. ruggieri g., selli r. (1949, 1950) il pliocene e il pstpliocene dell’emilia. giornale geologia, 20, 114; xviii int. geol. congress, london 1948, 9, 8593, london. sala b. (1986) bison schoetensacki freud from isernia la pineta (early mid-pleistocene, italy) and revision of the european species of bison. palaeontographia italica, 74, 113-170. scarabelli g. (1849) sui depositi delle ossa fossili esistenti nell’imolese. nuovi annali delle scienze naturali, 2, 10, 297-302. scarabelli g. (1881) carta geologica del monte castellaccio e dintorni presso imola. virano e teano roma. selli r. (1949a) smottamenti costieri avvenuti durante il siciliano al margine dell’appennino bolognese. atti xiv congr. geol. it., 387-388. selli r. (1949b) le conoscenze geologiche sul quaternario gassifero del polesine e del ferrarese settentrionale. atti vi convegno nazionale per il metano, succ. penada stampatori padova, p. 515537. selli r. (1962) le quaternarie marin du versant adriatique jonien de la peninsule italienne. quaternaria 6, 391-413. she a.v. (1997) an early quaternary bison population from untermassfeld: bison menneri sp. nov. das pleistozän von untermassfeld bei meiningen (thüringen), teil 1, 101-180. torre d., albianelli a., bertini a., ficcarelli g., masini f., napoleone g. (1996) paleomagnetic calibration of plio-pleistocene mammal localities in central italy. acta zool. cracov., 39, 1, 559-570. teilhard de chardin p., piveteau j. (1930) les mammifères fossiles de nihowan (chine). masson et cie, pp. 136. vai g.b. (1984) quando barrivano sul castellaccio gli ultimi elefanti. in: pagine di vita e storia imolesi, cars imola, 2, 195-219. vai g.b. (1988) a field trip guide to the romagna apennine geology: the lamone valley. in: de giuli c., vai g.b. (eds.), fossil vertebrates in the lamone valley, romagna apennines, int. work. "continental faunas at the miocene/pliocene boundary, 7-37. vai g.b. (1989) migrazione complessa del sistema fronte deformativo-avanfossa-cercine periferico: il caso dell'appennino settentrionale. memorie società geologica italiana 38 (1987), 95-105. vai g.b. (1995) introduzione alla geologia dell’appennino nord-orientale, sulle orme di scarabelli. in: pacciarelli m., vai g.b.(cur.), la collezione scarabelli 1. geologia, musei civ. imola cat. raccolte, grafis ed., 154-177. vai g.b., castellarin a. (1993) correlazione sinottica delle unità stratigrafiche nell'appennino settentrionale. studi geol. camerti, vol. spec. (1992/2) crop 1-1a, 171-185. vaiani s.c. (2000) testing the applicability of strontium isotope stratigraphy in marine to deltaic pleistocene deposits: an example from the lamone river valley (northern italy). journal of geology 108, 585-599. vereshchagin n.k. (1957) mammal remains of the lower quaternary deposits of the taman peninsula, vol. 22, trudy zoological institute, leningrad, 9-49. vislobokova i.a. (2008) the major stages in the evolution of artiodactyl communities from the pliocene-early middle pleistocene of northern eurasia: part 1. paleontological journal, 42, 3, 297-312. 23 revised bison skull from the salita di oriolo quarry near faenza, ... 24 sess 1_160211.pub il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 the impact of sea level changes on an urbanized area: the case of the city of bari (apulia) rossella pagliarulo1 & fabrizio antonioli 2 1 cnristituto di ricerca per la protezione idrogeologica. bari 2 enea, casaccia. roma corresponding author: r. pagliarulo <r.pagliarulo@ba.irpi.cnr.it> abstract: pagliarulo r. & antonioli f. the impact of sea level changes on an urbanized area: the case of the city of bari (apulia). (it issn 0394-3356, 2011) this paper considers the different depths of the ancient floor levels in the crypt of st. nicholas basilica (bari), built in 1087 ad along the sea, as markers and compares them to eustatic sea level curve for the adriatic coastline reconstructed on the basis of the lambeck’s predictive model for the late pleistocene and holocene changes in local relative sea level. (lambeck et al.,2011). the palaeo sea levels have been obtained measuring: 1) the pavement levels in the crypt; 2) the groundwater table at the time of the construction of the basilica and in 1956. the results give an interesting contribution to calibrate the predicted sea level curve for the last 1000 year. riassunto: pagliarulo r. & antonioli f. l’impatto delle variazioni del livello mare su un’area urbanizzata: il caso della città di bari (puglia). (it issn 0394-3356, 2011) questo lavoro prende in considerazioni diversi livelli di calpestio della cripta della basilica di san nicola a bari, costruita sul mare nel 1087 e li confronta con la locale curva di riferimento di risalita del modello di lambeck et al., (2011). i paleo livelli del mare sono stati ricavati da misure sulla superficie piezometrica della falda acquifera sia al tempo della costruzione della basilica, sia successivamente. i risultati forniscono interessanti spunti di confronto per la calibrazione della curva negli ultimi 1000 anni. key words: relative sea level curve, adriatic sea, watertable, seawater intrusion parole chiave: curva di risalita del mare, mare adriatico, falda, intrusione marina lately, published and new data are available in defining sea-level change in many location all along the italian coastline. (antonioli et al., 2009; lambeck et al., 2004; 2011). the database provides predicted sea level curves since the last glacial maximum. the curves are reconstructed on the basis of geomorphological markers, coastal archaeological data and sedimentary core analysis. this paper is a contribution to the use of a measurement methodology, to calibrate and adjust the predicted values of sea level rise. archeological data coming from past floor levels of the crypt of st. nicholas basilica in bari are used in comparing these depths to the predicted sea level curve for the last 1000 yr. the basilica, built between 1087 and 1197, safeguards the saint’s relics and stands imposing in the old town of bari overlooking the adriatic sea. (fig.1). the crypt was originary a hypogean. the old town of bari is located on a little peninsula protruding to the sea. from the geological point of view it is founded on limestones of the apulian carbonatic plate. in particular, the formation of “calcari di bari” represents the bedrock for the whole area and consists of a sequence of grey whitish limestones, dolomitic limestones and dolomites in strata whose thickness ranges from about some decimeters to a few meters. the age is referable to upper albian-early cenomanian. eustatic sea level change occurred since middle pleistocene characterized the coast with the deposition of marine terraces. (pieri et al., 2009). they are arranged in several orders, the lower ones outcrop on the western and eastern part of the town, partly deleted by urbanization. they consist in sand dune bodies, actually at a height of 4-5 m a.m.s.l., overlaying both the calcareous sandstones of upper pliocenelower pleistocene and the mesozoic limestones. these deposits consist of porous yellowish calcarenites with clear oblique lamination. the fossil content is given by gasteropoda and helix. (zezza, 1971). the age of the deposits can be referred to upper pleistocene. although they do not include any special indicator it is possible to refer these deposits to a generic thyrrenian. (pieri, 1975). for this reason uplift rates are rather difficult to determine. the south adriatic coast was not colonized by warm fauna during the warmest sea highstands, but it is considered to be stable. the functional depths of the ancient floor levels in the crypt of st. nicholas basilica enables us to determine the mean sea level, since the year of the construction, quite precisely. by means of historical sources it has been possible to have information about the piezometric surface of the groundwater, its changes and the relationship with the current and past sea level. this coastal area is affected by sea water intrusion. (cotecchia, 1981). it is the induced flow of sea water into fresh 48 50 49 water aquifers. because fresh water is less dense than salt water it floats on top. the boundary between salt water and fresh water is not distinct, the salt water interface is brackish with salt water and fresh water mixing. the rise in sea level causes flooding of coastal land by sea water, either for a long or a short period. in addition sea level changes boost sea water intrusion into coastal aquifer that are hydraulically connected to the sea. for this reason since 1087 it was necessary to raise the floor of the crypt as it has been flooding by sea water intrusion. (cotecchia et al., 1983) (fig. 2). fig. 1, the old town of bari and the location of st. nicholas basilica il borgo antico di bari e la localizzazione della basilica di san nicola  fig. 2, sea level changes and the impact of sea water intrusion on the structures of the crypt. variazioni del livello mare e influenza dell’intrusione marina sulle strutture della cripta.  the impact of sea level changes on an urbanized ... 50 ms. received: testo ricevuto il references antonioli f., ferranti f., fontana a., amorosi a., bondesan c., braitenberg c., dutton a., fontolan g., furlani s., lambeck k., mastronuzzi g., monaco c., spada g. & stocchi p. (2009) – holocene relative sea-level changes and vertical movements along the italian and istrian coastlines. quaternary international, 206 boll. soc. geol. it., 109, pp.102-133. cotecchia v. (1981) – methodologies adopted and results achieved in the investigation of seawater intrusion into the aquifer of apulia. geol. jb. c29 hannover, pp.1 -68. cotecchia v., tadolini t. & tulipano l. (1983) – sea water intrusion in the planning of groundwater resources protection and utilization in the apulia region (southern italy). geologia applicata e idrogeologia, 18, (ii), 367382. lambeck k., antonioli f., purcell a., & silenzi s. (2004) sea-level change along the italian coast for the past 10,000 yr. quaternary science reviews 23, pp.1567-1598. lambeck k., antonioli f., anzidei m., ferranti l., leoni g., scicchitano g. & silenzi s. (2011) sea level change along the italian coast during the holocene and projections for the future. quaternary international, 1-8 pieri p. (1975) – geologia della città di bari. memorie soc. geol. it, 14, 379-407. pieri p., sabato l., spalluto l. & tropeano m. (2009) – carta geologica dell’area urbana di bari. progetto carg. convegno sigea “geologia urbana di bari ed area metropolitana”, bari, novembre 2009. zezza f. (1971) – significato geologico e caratteristiche sedimentologiche delle dune e dei depositi di spiaggia fossili fra bari e monopoli. geologia applicata e idrogeologia, vi, 1-15. r. pagliarulo & f. antonioli january 13, 2011 13 gennaio 2011 imp.d'argenio la “geologia stratigrafica” di azzaroli e cita a 45 anni dalla sua pubblicazione bruno d'argenio dipartimento di scienze della terra, università di napoli federco ii; l.go s. marcellino 10, 80138 na iamc istituto per l'ambiente marino costiero del cnr calata porta di massa, 80133 na abstract: b. d’argenio, stratigraphic geology by a. azzaroli and m. b. cita, 45 years later. a concise review of a textbook of stratigraphy that was very influential in italy during the late sixties and seventies of the last century; a relevant historical moment of paradigmatic and scientific changes within the international geologic community. parole chiave: stratigrafia, italia, commissione italiana di stratigrafia. keywords: stratigraphy, italy, italian stratigraphy commission. il quaternario italian journal of quaternary sciences 21(1a), 2008 9-10 quando, alcuni mesi or sono, ho scelto questo titolo per commentare, dopo 45 anni, un evento poco valorizzato: la pubblicazione del primo libro di testo moderno di stratigrafia in italia, non mi ero reso conto che non sarebbe stato semplice parlarne adeguatamente nei pochi minuti a mia disposizione. sarò perciò molto schematico, e certo non esauriente, in queste considerazioni. penso che pochi dei presenti erano già attivi nella ricerca nei primi anni 60 dello scorso secolo, per cui mi sembra opportuno iniziare con qualche considerazione sulle conoscenze stratigrafiche di quegli anni. voglio innanzitutto sottolineare la importanza che il testo di augusto azzaroli e maria bianca cita ha avuto in italia non solo per gli studenti (cui formalmente era dedicato) ma anche per quei giovani ricercatori come me che, a quel tempo, avevano ben pochi riferimenti “moderni” in italiano (se si eccettua forse la terra di trevisan e tongiorgi del 1958 in cui peraltro alla stratigrafia formale si faceva appena cenno). tutto ciò soprattutto per gli esempi usati che, salvo per alcuni intervalli (ad es. il quaternario) e per alcune aree (ad es. le alpi meridionali), ci imponevano di destreggiarci tra i classici testi francesi (la geologie stratigraphique di maurice gignoux in primis), alquanto generici nei formalismi propri della stratigrafia codificata, e quelli di lingua inglese, più ricchi di regole anche empiriche, ma privi di riferimenti nostrani (ad es. l'ottimo stratigraphy and sedimentation di w.c. krumbein e l.l. sloss, 1963, ii ed.). c'è quindi un merito “storico” in questo testo: quello di aver proposto un quadro di riferimento sia normativo che esemplificativo adatto alle esigenze italiane degli anni 60. personalmente posso ricordare quanto i primi due volumi della geologia stratigrafica mi furono di aiuto allorché ebbi modo di spendere un anno a princeton tra il 1965 e il 1966. qui, potei seguire un piacevolissimo quanto poco accademico corso di geologia stratigrafica svolto da hollis hedberg: uno dei padri fondatori della stratigrafia formale moderna. un corso tenuto a casa sua, di sera, con birra e patatine fritte e una collezione impressionante di testi, carte geologiche ed estratti originali degli ultimi 200 anni. qui l'aver letto il testo di azzaroli e cita, mi consentì di partecipare con successo ad un processo di acculturamento che era anche una sorta di gara, in cui ciascuno aveva assegnato (o si sceglieva) un argomento su cui di volta in volta riferire, distribuendo poi a tutti un testo che veniva letto, commentato ed emendato seduta stante, consentendo a tutti, dopo una quindicina di incontri, di avere un volume ciclostilato “collettivo”, ricco di definizioni, schemi e figure. ma torniamo alla geologia stratigrafica di azzaroli e cita. i tre volumi (i primi due del 1963 e il terzo del 1967) per un totale di oltre 1000 pagine, contengono una introduzione generale ai “principi di stratigrafia” e una parte “storica” (dal pre cambiano al quaternario) che occupa oltre metà del primo volume e gli interi altri due volumi. mi soffermerò particolarmente sul primo volume giacché contiene la parte più innovativa in cui si presentano le idee moderne per il tempo: gli ambienti di sedimentazione, le variazioni relative de livello del mare e i rapporti tra sedimentazione e tettonica. vi si colgono concetti ispirati ad autori come pettijohn o twenofel: una discontinuità rispetto ai testi italiani, ma anche a quelli in lingua francese del tempo. mancano purtroppo i riferimenti bibliografici e ciò è forse il limite maggiore alla utilizzazione dei concetti espressi anche attraverso una integrazione con le fonti originali. ciò vale anche per la cronologia numerica in cui si fa riferimento non solo ai metodi basati sul decadimento radioattivo ma anche a quelli di tipo astronomico, con cenni ai calcoli di milankovic (sia pure con una punta di scetticismo). 10 b. d’argenio nel capitolo dedicato agli ambienti di sedimentazione la trattazione è di tipo tradizionale, anche se viene presentata qualche idea moderna, ricordando la dinamica delle “scogliere” così come vista da henson: concetti che apriranno la strada alla stratigrafia sequenziale del decennio successivo. anche la discussione delle variazioni relative del livello marino (“trasgressioni e regressioni”) è ben impostata. manca però ogni cenno all'eustatismo che al tempo non era ancora “di moda”. infine nel capitolo dedicato ai rapporti tra sedimentazione e tettonica si fa ancora riferimento alle geosinclinali, ma è interessante notare diverse note critiche alle generalizzazioni, allora molto di moda, di jean aubouin. classico infine è l'approccio alla stratigrafia formale con chiare distinzioni tra le varie categorie di unità stratigrafiche e una buona discussione sulla problematica degli stratotipi. molto interessante é il riferimento al codice di nomenclatura stratigrafica americano del 1961, che servirà poi di base alle sue versioni successive. ugualmente ampio e approfondito è il capitolo dedicato alle correlazioni stratigrafiche, una delle tematiche che andrà sempre più evolvendo verso l'approccio quantitativo (biostratigrafico o strumentale che sia). mi fermo qui nel commentare questa prima parte del primo volume. i capitoli successivi e quelli degli altri due volumi sono ugualmente pregevoli per la quantità degli esempi italiani utilizzati (anche qui va rammentata l'assenza di riferimenti bibliografici che avrebbe dato ai questi esempi una valenza certamente maggiore). concludo ricordando ancora una volta i primi anni '60, tempi nei quali cominciava una “rivoluzione culturale” nelle scienze della terra, la più importante dai tempi di lyell e darwin, e a circa un secolo da quella, col ritorno ad una concezione unificante della geologia, anche se ispirata ad un pervasivo mobilismo. per la verità va ricordato che nella stratigrafia, intesa nel senso ampio di analisi e correlazione delle successioni di eventi, questi effetti si sono fatti sentire solo negli anni '70, con la utilizzazione rutinaria di concetti come eustatismo e ciclicità di elevata frequenza e l'impiego di metodologie analitico-strumentali “globali”, quali la geochimica isotopica o il palemagnetismo. ci si potrebbe chiedere se questo rapido processo di cambiamento di paradigmi abbia avuto conseguenze rilevanti anche in quella parte della stratigrafia formale che è oggetto delle discussioni di oggi e domani. ed è a questa domanda, credo, che dobbiamo dare una risposta. perché se è vero che nella nomenclatura stratigrafica valgono quei principi generali (correttezza formale, accessibilità dei controlli e salvaguarda delle priorità) che sono validi nella tassonomia botanica, zoologica e paleontologica (pur con le relative specificità), è anche vero che le moderne metodologie analitiche consentono di esercitare controlli che quarant'anni or sono erano appena nel loro stato nascente (si pensi solo ai già ricordati paleomagnetismo e geochimica isotopica). in questo contesto di rapidi avanzamenti metodologici si rischia di dimenticare che vi sono aspetti relativi agli oggetti analizzati: i corpi geologici, e i loro rapporti e i loro fossili, che furono nel tempo, stabiliti da madre natura e risultano pertanto “immodificabili” come ci insegnano le norme della stratigrafia formale. ciò giustifica la necessità impellente, oggi, di avere una commissione italiana di stratigrafia autorevole e fattiva. maria bianca cita, e in piccola parte io stesso, abbiamo cercato di riproporre, con l'aiuto degli altri colleghi della cis, una commissione attiva e vigile, ma é chiaro che senza il contributo convinto della comunità scientifica italiana queste finalità non potranno essere realizzate, anche perché è necessario che altri tra voi prendano il nostro posto per consentire di mantenere l'alto livello scientifico degli scorsi decenni che ha dato al nostro paese una posizione di rilievo nella comunità stratigrafica internazionale. ms. ricevuto il 2 aprile 2008 testo definitivo ricevuto il 17 aprile 2008 ms. received: april 2, 2008 final text received: april 17, 2008 base late prehistory and environmental changes along the débé river in the lower sourou valley (burkina faso, west africa) alessandro fontana1, paolo mozzi1, aldino bondesan1, armando de guio2, lassinà koté3 1 dipartimento di geografia, università degli studi di padova, padova (italy) 2 dipartimento di archeologia, università degli studi di padova, padova (italy) 3 laboratoire d'archeologié, université de ouagadougou, ouagadougou (burkina faso) corresponding author: a. fontana <alessandro.fontana@unipd.it> abstract: fontana a. et al., late prehistory and environmental changes along the débé river in the lower sourou valley (burkina faso, west africa). (it issn 0394-3356, 2010). about twenty prehistoric sites have been found on the banks of the débé river, a tributary of the souoru river in nw burkina faso, near the boundary with mali. these sites consist of surface scatters of hundreds of flint artefacts and polished stone tools (mainly little adzes), associated with abundant, roughly worked discarded materials, which suggest in situ production. the most investigated area is the site of kourani 5, in which 6 explorative pits were opened; some hand boreholes were realized along the débé and sourou to understand the relationships existing between alluvial evolution and ancient population. the artefacts could be dated to a time range within the ii millennium bc (within a “neolithic”, or “ceramic late stone age”, or “later stone age” phase, according to different authors). a preliminary classification is proposed here on the basis of a number of key reference sequences and known cultural facies from burkina faso and the wider sub-saharan west africa. the débé riverbed is at present occupied by stagnant ponds, seasonally fed by rain water. the sedimentary facies of the channel deposits indicate that it was formerly interested by flowing water inside its 12 m high scarps. this probably happened in the relatively wet, middle holocene climatic setting, before the shift to drier climatic conditions which have affected the whole west africa since the 2nd – 1st millennium bc. during the prehistoric occupation, the flint-bearing layers of the bedrock were outcropping along the river scarps and could be easily quarried. the other raw materials worked in the area, such as quartz and green stones, are not present along the lower stretch of débé and were thus imported. the débé channel was later filled in by silty-clay sediments of colluvial origin, in a semi-arid environment similar to the present one, characterized by increasingly enhanced erosion due to modern anthropic activities. the presence of accessible flint outcrops and the use of exotic raw material support the hypothesis that the sourou valley could have developed an organized territorial system and become part of a medium to long-range exchange network. riassunto: fontana a. et al., preistoria recente e cambiamenti ambientali lungo il fiume débé nella bassa valle del sourou (burkina faso, africa occidentale). (it issn 0394-3356, 2010). durante due missioni geoarcheologiche condotte nel 2007 nel burkina faso nord occidentale, nella pianura del fiume sourou sono stati scoperti circa 20 siti preistorici. le aree archeologiche si trovano lungo il débé, affluente del sourou, tra 15 e 50 km a monte della loro confluenza. i siti corrispondono a concentrazioni di strumenti in pietra scheggiata e levigata (soprattutto accettine e ascette) affioranti lungo le sponde del fiume, sulla superficie della piana. nei siti di maggiori dimensioni, che raggiungono un’estensione di quasi 10 ettari, sono presenti anche migliaia di schegge di sbozzatura e lavorazione. l’area archeologica meglio indagata è quella di kourani 5 (kou5), dove sono state aperte 6 trincee esplorative; per comprendere i rapporti tra depositi alluvionali e dinamica insediativa antica sono stati effettuati alcuni carotaggi stratigrafici fino a 7 m di profondità sia presso questo sito, sia lungo il corso del débé e del sourou. la piatta valle del sourou, che si estende tra il delta interno del fiume niger e la grande ansa del mou-houn (volta nero), è bordata ai lati dal plateau mossi e da quello di bandiagara e corrisponde ad un corridoio ecologico lungo cui avviene la transizione tra la zona sud-saheliana e quella sudanese, con passaggio da condizioni predesertiche ad ambienti di savana arborata. la zona studiata è quindi un settore particolarmente sensibile ai cambiamenti ambientali recenti e passati ed è stata interessata da importanti movimenti di popolazione durante l’olocene recente, probabilmente indotti dalla siccità. nei nuovi siti individuati la presenza di numerose asce e accette in pietra verde, e la loro associazione con microliti semilunati, permette di attribuire genericamente tali complessi litici ad un intervallo temporale compreso nel ii millennio a.c (in una fase del “neolitico”, o “ceramic late stone age”, o “later stone age”, secondo i diversi autori e le diverse terminologie di riferimento). questa corrisponde alla fase olocenica in cui in africa occidentale si diffusero gli strumenti in pietra levigata ed è grossomodo compresa tra 3000 e 800 a.c. viene qui avanzato un primo inquadramento sulla base di sequenze-chiave e facies culturali note del burkina faso e del più vasto contesto dell’africa occidentale sub-sahariana. le informazioni stratigrafiche e geomorfologiche indicano che, durante la frequentazione preistorica, il fiume débé era caratterizzato da portate tali da mantenere l’alveo libero dal sedimento e incassato di circa 2 m rispetto alla pianura circostante. tale assetto consentiva l’affioramento del substrato roccioso lungo le sue sponde, rendendo visibili formazioni marnoso-calcaree contenenti noduli e liste di selce. questa materia prima veniva cavata e lavorata nel sito di kourani 5, dove venivano realizzati anche strumenti in pietra levigata da rocce grezze importate da almeno alcune decine di chilometri di distanza. l’esistenza di numerosi siti di diverse dimensioni, la loro probabile appartenenza alla medesima fase cronologica, la specializzazioni di alcuni di essi nella produzione di strumenti litici induce a ipotizzare l’esistenza di un complesso sistema territoriale che poteva essere parte di circuiti di scambio socio economici di medio ed ampio raggio. la notevole differenza di portate e regime idrologico del débé è probabilmente riconducibile all’inaridimento che ha caratterizzato tutta l’area a sud del sahara a partire dal i millennio a.c. tuttora in corso. questo inaridimento ha causato il riempimento dell’alveo del fiume da parte di colluvi limosi; l’alimentazione di tali depositi è ricollegabile all’erosione areale avvenuta negli ultimi 3 millenni lungo le sponde del fiume per effetto della minor copertura forestale e delle pratiche agro-pastorali. key words: west africa, burkina faso, holocene, prehistory, paleohydrography parole chiave: africa occidentale, burkina faso, olocene, preistoria, paleoidrografia il quaternario italian journal of quaternary sciences 23(2), 2010 199-216 available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 30 (2), 2017, iii-iv in the last two decades, a number of investigations has brought significant advances in the definition of the stratigraphy and chronology of this crucial portion of the upper pleistocene in the italian alps and piedmont alluvial basins. the aiqua workshop, sponsored by the terpro and saccom inqua commissions and by the igg-cnr and the department of geosciences of the university of padova, was held at the department of geosciences of padova, on june 22 nd -23 nd , 2017 (scientific and organizing committee: p. mozzi, g. monegato, a. fontana, s. rossato). it was attended by about 60 participants. the main aim of the workshop was to provide a comprehensive, state-of-the-art framework of the geomorphic, sedimentary and palaeoenvironmental events that occurred in this key area, which is located at the critical transition between continental europe and the mediterranean region. the presence of longinvestigated upper palaeolithic sites in the italian subalpine region also rises stimulating questions on the interaction between early humans and extreme environmental conditions and landscapes of the last glaciation. hot topics discussed during the workshop were: the onset, phases and termination of the alpine lgm sediment production and delivery from glacial and periglacial areas to the basin piedmont and in-valley terminal glacial tongues lgm and late glacial climates and environments dating methods and integrated chronologies territories and settlements of the upper paleolithic hunter-gatherers. the workshop was articulated in a first day of solicited talks, which embraced some major issues on the last glaciation in the italian side of the alps: the alpine glacial systems (g. monegato) and related megafans (a. fontana, p. mozzi, s. rossato), the po river lowstand wedge (c. pellegrini, a. asioli, k.m. boahcs, t.m. drexler, m.l. sweet, v. maselli, m. rovere, t. tesi, f. gamberi, g. dalla valle, f. trincardi), the lgm and lateglacial stadials in the fig. 1 participants of the aiqua field trip on the terminal moraines of the piave glacier at quero (photo by f. finocchiaro). aiqua workshop: updates on the chronology, stratigraphy and environments of the last glacial maximum and the late glacial on the southern side of the alps paolo mozzi 1 , giovanni monegato 2 corresponding author: p. mozzi <paolo.mozzi@unipd.it> 1 dipartimento di geoscienze, padova, italy 2 cnr igg, torino, italy abstract: the aiqua workshop, sponsored by the terpro and saccom inqua commissions and by the igg-cnr and the department of geosciences of the university of padova, was held at the department of geosciences of padova, on june 22 nd -23 nd , 2017 (scientific and organizing committee: p. mozzi, g. monegato, a. fontana, s. rossato). the workshop focused on the geomorphic, sedimentary and palaeoenvironmental events that occurred in the southern alpine region and related po plain, venetian-friulian plain and adriatic basin during the last glacial maximum and the late glacial. about 60 participants attended the workshop, with nine solicited talks, five short communications and posters, and ample time devoted to discussion. the second day consisted in a field trip in the venetian prealps. keywords: last glaciation, last glacial maximum, late glacial, alps, italy iv mozzi p. & monegato g. maritime alps (a. ribolini m. spagnolo, p.r. federici), the speleothem record in the eastern italian alps (a. borsato, r. belli, s. frisia, j. hellstrom), ecosystems and environments (c. ravazzi, r. pini, f. vallè), loess deposition in the po plain (a. zerboni, m. cremaschi), paleolithic settlements between the apennines and the prealps (m. peresani), and rock glacier evolution in the alps (r. colucci, m. guglielmin). time was also devoted to short presentations and posters by the participants, concerning glacigenic landforms and deposits in the ivrea end-moraine system (gianotti et al.), slovenian alps (žebre et al.) and julian alps (finocchiaro et al.), as well as loess in the ligurian alps (rellini et al.) and a review of the mammuthus-coelodonta faunal complex in italy during the last glaciation (menicozzi et al.). at the end of the presentations, it followed a plenary discussion on the timing of landscape evolution and palaeoecosystems from the adriatic plain to the alps during the last glacial maximum and the late glacial on the second day there was a field trip in the venetian prealps, led by p. mozzi, g. monegato and s. rossato. this excursion was centered on glacier arrival, acme and decay in the terminal tracts of the brenta and piave valleys, and the related dynamic response of the glaciofluvial system. the first stop concerned the piave river terraces around biadene, then we moved to quero, where we visited the lgm end-moraine system of the piave glacier. after lunch, we visited the arsiè-cismon area, where we observed the moraines of the brenta glacier and related glaciofluvial deposits. ms. received: december 15, 2017 final text received: december 24, 2017 fig. 2 view on the terminal tract of the piave valley from the lgm terminal moraines of quero (photo by s. rossato). fig. 3 upper pleistocene fluvial deposits of the piave river in the montebelluna megafan (caravaggio gravel pit) (photo p. mozzi). fig. 4 polygenetic lgm glaciofluvial deposits of the brenta river in the valsugana valley (cismon del grappa) (photo p. mozzi). sess 1_160211.pub il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 luminescence chronology of pleistocene marine terraces of the sicily and calabria coastal areas gloria maria ristuccia1,2, anna maria gueli2, carmelo monaco1 giuseppe stella2 & sebastiano olindo troja2 1dipartimento di scienze geologiche, università di catania, italy 2ph3dra laboratory, dipartimento di fisica e astronomia, università di catania & infn catania, italy corresponding author: g.m. ristuccia <gloria.ristuccia@ct.infn.it> abstract: ristuccia g.m. et al., luminescence chronology of pleistocene marine terraces of the sicily and calabria coastal areas. (it issn 0394-3356, 2011) the calabrian arc and north-eastern sicily are sectors of central mediterranean where the effects of quaternary tectonics are visible and regional uplift is accompanied by marine terracing along the coastal areas. in this paper, the application of optically stimulated luminescence (osl) dating based on the single-aliquot regenerative-dose (sar) protocol for sand-sized quartz is investigated. we present new osl age estimates of pleistocene marine terrace deposits located in capo vaticano peninsula and in the sant’agata di militello costal area, where a complete series, characterized by both marine and continental deposits, occurs. current elevations of marine terraces also suggest that these portions of the calabrian arc have been affected by a vigorous tectonic uplift during the last 330 ka, probably due to sum of regional uplift and fault activity. riassunto: ristuccia g.m. et al., cronologia tramite luminescenza dei terrazzi marini pleistocenici presenti lungo l’area costale della sicilia e della calabria meridionale. (it issn 0394-3356, 2011) l’arco calabro e la sicilia nord-orientale sono settori del mediterraneo centrale dove gli effetti della tettonica quaternaria sono ben visibili e il sollevamento regionale è evidenziato da un terrazzamento marino lungo le aree costiere. in questo lavoro è stata investigata la possibilità di datare i depositi terrazzati tramite la luminescenza otticamente stimolata (osl) mediante il protocollo della singola aliquota (sar) su quarzo estratto dai sedimenti. i risultati ottenuti hanno permesso di ottenere nuove cronologie dei terrazzi pleistocenici localizzati lungo la penisola di capo vaticano e l’area costiera di sant’agata di militello. le attuali linee di costa suggeriscono, insieme ai dati ottenuti, che queste porzioni dell’arco calabro sono state soggette ad un forte sollevamento durante gli ultimi 330 ka, probabilmente a causa della componente regionale sommata ad attività di faglie. key words: marine terraces, uplift rate, luminescence parole chiave: terrazzi marini, rate di sollevamento, luminescenza 1. introduction marine terraces are geomorphic surfaces that have been exposed by a lowering of sea level or a tectonic uplift; their inner edges indicate the location of a palaeoshoreline. therefore the timing of terrace formation can provide information on coastal uplift and allows to determine local deformation related active faulting. in this paper we investigate the middle-upper pleistocene deformation rates of some terraces of the sicily and calabria coastal areas (capo vaticano, western calabria; sant’agata di militello, northern sicily). in these southern italy regions, the effects of intense quaternary tectonic activity were evident. at first, the marine surfaces, with their relative inner edges, have been mapped using 1:25000 scale topographic maps of the igm integrated with analysis of 1:33000 and 1:10000 scale aerial photographs. moreover, osl dating of marine terraces deposits, together with detailed morpho-structural analysis of tectonic elements, allowed us to reconstruct the tectonic evolution of analyzed coastal area and to constrain the relationships between marine terracing and normal faulting in a precise time range. 2. geological setting the capo vaticano peninsula is a structural high located along the tyrrhenian side of the calabrian arc (fig. 1), an arc-shaped portion of the central mediterranean orogen extruded towards the oceanic crust of the ionian basin during the final stage of the africa-europe collision (malinverno & ryan, 1986). late quaternary tectonics along the calabrian arc are characterized by the occurrence of a prominent normal fault belt along the western side of calabria and ne coast of sicily, developed in response to wnw,ese regional extension (siculo-calabrian rift zone; monaco & tortorici, 2000). since the middle pleistocene, extensional tectonics have been coupled with a strong regional uplifting which developed spectacular flights of marine terraces (westaway, 1993; ghisetti, 1981; 1984; miyauchi et al., 1994; bianca et al., 1999; catalano & de guidi, 2003; tortorici et al., 2003; valensise & pantosti, 1992; ferranti et al., 2006). 54 56 55 the sant’agata di militello coastal area is located along the tyrrhenian shore of ne sicily about 100 km west of the town of messina. the area is a part of the southernmost sector of the calabrian arc. the samples from each marine terrace (seven samples from capo vaticano peninsula and three from sant’agata di militello) were collected from 60 cm long cylindrical cores (5 cm) extracted from fresh outcrops by black corebarrel to dating by optically stimulated luminescence (osl) methodology. the ends of each cylinder were sealed with black tape for transportation because it is of critical importance for osl measurements that the samples are not exposed to daylight. however, the outer layers have been used in the laboratory for radioactivity measurements and water content determination. 3. methodology osl has become an important technique for studying earth surface processes and dating sediments. the general equation used to determine the age, time from the last optical bleaching until today, is: where the equivalent dose (ed) is the total dose absorbed from instant zero until the moment of measurement in the laboratory, while the annual dose (ad) is the average energy absorbed for unit mass by the specimen in one year as the result of the radioactivity present both in the specimen itself and in the environment. in the present work, the experimental values of ed were determined using the single aliquot regeneration protocol (sar) (murray & wintle a. g., 2000; 2003) coupled with )/( )( )( kagydoseannual gydoseequivalent aage = coarse grain sample preparation technique (bianca et al., 2010). the coarse grain fraction consists in hf etched quartz grains within the size range 100-300 μm that were extracted from the sediment using standard separation procedures. the purity of quartz fraction was verified by infrared stimulation on some representative aliquots for each sample (aitken, 1998). the age is calculated as outlined in equation: age = ed/(f·dβ+dγ+cosm) where f is the attenuation factor depending on grain size (mejdahl, 1979); dβ contribution was calculated using concentration values of u, th and k determined by the icp-ms technique. to determine beta and gamma dose rates, annual dose conversion factors by adamiec & aitken (1998) were used. these dose rates were validated from a comparison with gamma dose measured in situ at the sampling points with a portable nai(tl) probe. the contribution of cosmic radiation to the total dose-rate was calculated using present depth (prescott & hutton, 1988; 1994) considering the density and the depth of the sample below the surface. the moisture-corrected dose-rates values are obtained considering the present-day water content from win-situ values (aitken, 1998) using the attenuation factors given by zimmerman (1971). 4. results and conclusions absolute dating of middle-upper pleistocene marine sediments by osl methodology yielded new constraints for correlating the seven orders of marine terraces exposed in the capo vaticano peninsula with the last quaternary interglacial stages. in fact, the distinct marine terraces can be correlated with the last seven high-stands of the global fig. 1, regional tectonic map of the southern part of the calabrian arc carta tettonica regionale della porzione meridionale dell’arco calabro luminescence chronology of pleistocene marine ... 56 ms. received: testo ricevuto il eustatic curve (mis 7.5, 7.3, 7.1, 5.5, 5.3, 5.1 and 3.3). present marine terrace elevations also suggest that this portion of calabrian arc has been affected by a vigorous tectonic uplift during the last 236 ka, locally characterized by rates up to ~2 mm/ a, responsible for the preservation of all marine terraces related to the entire series of the last major sea level high-stands. moreover, the geometry of the palaeoshorelines indicates that the raising process was characterised by uplift rates increasing toward the sw, resulting in the tilting of the whole peninsula toward the ne. it represents the footwall of both the sw,ne and the wnw,ese striking onshore and/or offshore normal fault systems. consequently, the uplifting of the area, started just before 236 ka ago, can be considered to represent the sum of the activity of these fault segments and the regional uplift. in the ne sector of sicily, between acquedolci and sant’agata di militello, the estimated rates highlight a constant uplifting of 0.7-0.8 mm/a during the last 330 ka. instead, between sant’agata di militello and capo d’orlando, the uplifting is not constant, probably due to the activity of the capo d’orlando fault. by comparing the uplift rates along crosssections through the ne sector, where the capo d’orlando fault occurs, and the sw sector, where it ends, terraces i, ii and iii, laying on the hanging wall of the fault, raised at a slower rate (0.35 mm/ a) than the terraces located in the sw sector. in the same way, the terraces iv and v, laying on the footwall of fault, raised at a faster rate (0.92 mm/a) than the sw terraces (orioli et al., 2011, in preparation). in conclusion, the morphological analysis of the marine terraces and the deformation pattern confirm the occurrence of an important tectonic component in the total amount of uplift, which is related to the middle-upper pleistocene activity of normal faults. references adamiec g. & aitken m.j. 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(1971) thermoluminescent dating of upper palaeolithic fired clay from dolnì vĕstonice. archaeometry, 13, 53-57. g.m. ristuccia et al. january 13, 2011 13 gennaio 2011 03passaroetal integrated geophysical investigation applied to the definition of buried and outcropping targets of archaeological relevance in very shallow water passaro s.1, budillon f.1, ruggieri s.1, bilotti g.2, cipriani m.3, di maio r.4, d’isanto c.1, giordano f.5, leggieri c.3, marsella e.1, soldovieri m.g.4 1 iamc-cnr, napoli, e-mail:salvatore.passaro@iamc.cnr.it 2 area lavori pubblici e demanio marittimo, comune di acropoli 3 soprintendenza per i beni archeologici delle province di salerno, avellino e benevento, salerno 4 dipartimento di scienze della terra, università federico ii, napoli 5 dipartimento di scienze per l'ambiente, università "parthenope", napoli abstract: passaro s. et al., integrated geophysical investigation applied to the definition of buried and outcropping targets of archaeological relevance in very shallow water. (it issn 0394-3356, 2009). the results of a marine survey aimed at detecting archaeological targets in coastal areas by means the integration of different geophysical methods (multibeam bathymetry, high-resolution seismic, geoelectric and magnetism) are presented. the case study is a shipwreck recognised off the shore of agropoli town (salerno, southern italy) over a sandy sea-bottom at about 5 m of water depth. each geophysical method has its peculiarity and detection capability depending on a wide range of factors such as: geological setting, consistency and grain size of sea-bottom sediments, burial and nature (e.g. metallic/non metallic) of the targets, water depth, etc. it is worth stressing that there is a high reduction of the ambiguities inherent in each method when a multiple approach strategy is adopted. we believe that this type of investigation may contribute to establishing a quality standard for such a category of surveys that can be adopted by local administrators and coastal managers wherever archaeological exploration is required. riassunto. passaro s. et al., integrazione di metodi di prospezione geofisici per il rilievo di unità di interesse archeologico (sepolte o sommerse) in ambiente marino costiero. (it issn 0394-3356, 2009). in questo lavoro presentiamo il risultato di indagini effettuate con l’utilizzo di diversi metodi di geofisica marina, finalizzate alla ricerca di oggetti di interesse archeologico in mare (si intendono compresi i relitti storici o contemporanei). rilievi morfo-batimetrici, sismo-acustici, geoelettrici e magnetometrici sono stati effettuati al largo del litorale di agropoli (salerno, italia meridionale) su un relitto di nave della seconda guerra mondiale posto a circa 5 m di profondità su un fondale sabbioso. il caso di studio ha permesso di analizzare problemi ed inconvenienti correlati alle diverse tecniche geofisiche, in relazione a variabili quali: contesto geologico, natura e granulometria dei sedimenti al fondo, grado di seppellimento dell’oggetto, costituzione (metallica/non metallica) degli oggetti o dei relitti, profondità della colonna d’acqua, etc. l’utilizzo incrociato di dati derivanti da più tecniche di acquisizione ha permesso inoltre di ridurre sensibilmente il margine di errore interpretativo sulla natura degli oggetti e/o dei relitti osservati in sito. lo scopo del lavoro è stato quello di individuare criteri standard di riferimento che consentano scelte oggettive delle tecniche di investigazione di geofisica marina da utilizzare per il rinvenimento di relitti in zone costiere. una buona conoscenza, infatti, dei limiti e delle possibilità di ciascun metodo può influenzare positivamente la scelta delle amministrazioni locali impegnate nello sviluppo sostenibile delle zone costiere. keywords:magnetics, marine geoelectrical measurements, multibeam swath bathymetry, monochannel reflection seismic. parole chiave: metodo magnetico, misure geoelettriche, batimetrica multifascio, sismica a riflessione monocanale. il quaternario italian journal of quaternary sciences 22(1), 2009 33-38 1. introduction sea water geophysical exploration aimed towards reidentification of targets of archaeological relevance is strongly constrained by time of data acquisition and processing. feasibility studies in areas with potential archaeological interest are often required to be quick when the presence of a possible target has to be recognised, and this implies the use of exploration methods with a swift data response. in this regard, we have selected some standard geophysical techniques typically used in marine exploration, and tried to analyze them in regards to different aspects. parameters that need to be considered are: geological nature of the investigated sector (volcanic or non-volcanic) provided by magnetic prospecting, textures of bottom sediments (clays, silts, sands or gravel) provided by seismic surveys, while composition and displacement of targets (buried or outcropping), depth of water column might affect the performance of all the techniques here considered. the occurrence of outcropping items is well detected by using morphobathymetric surveys, i.e. multibeam swath bathymetry and side scan sonar. multibeam systems are echosounders, usually mounted on keel, made up of one hundred or more transductors, that allow te mapping of large swaths of the seafloor using acoustic reflections caused by water-sediment interface. side scan sonar systems, typically towed, use internal roughness of materials to explore the seafloor, through the evaluation of lateral backscattering. requirement for buried objects explorations are penetration of sediments without lack of resolution. magnetic surveys are used when expected archaeological targets differ from surrounding materials in terms of internal magnetic susceptibility. high-resolution mono34 s. passaro et al. channel seismic reflection surveys use active acoustic sources (variable in shape, amplitude, frequencies) to provide a sonic section of the subsurface, where anomalies are related to local variations of acoustic impedance (i.e. the product of density and acoustic velocity). the choice of the seismic source-type could be strategic. marine geoelectrical methods, just like on-land measurements, use properties of materials to give different answers to an electrical impulse. local anomalies, due to electrical resistivity contrasts, can be used to identify possible target location. a survey using all of the above methods has been carried out over a submerged beach along the agropoli shore (salerno, italy) by a research team of the institute for coastal and marine environment (iamc) of national research council (cnr), supported by the "parthenope" and “federico ii” universities of naples, with the aim of recognizing buried metrical objects below the sandy seabed. the survey discovered the presence of a shipwreck, that is a military vessel probably sunk during the second world war, in the course of the salerno landing operations. 2. geophysical exploration 2.1 outcropping targets: morphobathymetric surveys (mbes) mbes data records are usually processed with a reply of swaths, and the removal of erroneous measurements (spikes). data are then reorganized in a mxn matrix (digital terrain model, dtm), where every cell of the grid represents a depth quote. swath bathymetry equipments are characterized by frequency-dependent vertical resolution and depthdependent horizontal resolution (“footprint”), the dimensions of which represent a detection limit with respect to the grid cell size of dtm. the reported dataset was collected with a seabat 8125 (reson-thales) echosounder/sonar system with 240 beams, 120° of swath coverage and a pulse frequency of 455 khz, particularly suitable for applications in shallow waters (max 80 metres of depth). nadir areal footprint dimension is a function of depth and technical characteristics of the equipment. in shallow waters, high frequency mbes systems are able to map the seafloor with an adequate grid cell size, clearly showing potential targets. fig.1 is indicative of how fast the resolution degrades with respect to the increment of cell dimensions. where footprint dimensions are not sensibly smaller than the targets, the use of towed side scan sonar (sss) systems is strongly recommended. advantages related to the use of this system are evident, in the sense that sss is considerably closer to the source with respect to mbes. side scan sonar is an acoustic tool used to generate image map of the seafloor and particularly suitable for outcropping target detection. typically, the system's transducer is allocated in a towfish, which is towed through the water a few metres above the bottom. the reflected acoustic returns are processed into an image fig. 1 outcropping bodies are well detected with the use of swath bathymetry. here we show search results through a high resolution 20x20cm dtm (digital terrain model) obtained with the use of reson seabat 8125 multibeam echosounder, and processed with the pds2000 (reson-tales) software (a). this resolution is difficult to obtain, because of the intrinsic instrumental nature (the horizontal resolution is a function of depth of water column and instrumental characteristics, such as number of beams, angle wideness, etc.), but in such cases, multibeam images are equivalent to side scan sonar pictures in terms of horizontal target definition. the obtained dtm shows a perturbation in normal sedimentation, due to shipwreck outcropping, acting as an obstacle for longshore currents (quinn, 2006). b, c and d represents the same data proposed with a grid cell size of 0.5, 1 and 2 metres, respectively. the shipwreck presence (a) is clearly identified only with highest resolution grids (dimensions are 30x10 metres). i target di dimensioni metriche affioranti a fondo mare sono ben evidenziati dai rilievi batimetrici ottenuti con sistemi multifascio. in figura è mostrato un dtm (digital terrain model) alla risoluzione di 20x20 cm, realizzato acquisendo i dati di profondità con il reson seabat 8125 e processando con il software pds2000 (reson-tales). la risoluzione è funzione delle caratteristiche dello strumento utilizzato (numero di beam emessi, ampiezza del fascio) e della profondità d’acqua alla quale si opera. in alcuni casi si possono ottenere immagini multibeam paragonabili, come grado di definizione orizzontale, alle immagini side scan sonar. nell’esempio in figura è visibile la perturbazione del fondale circostante il relitto, dovuta all’interferenza dell’ostacolo con le correnti lungocosta (quinn, 2006). b, c e d mostrano l’area del relitto riproducendo lo stesso dato con tre differenti dimensioni di cella del grid (0.5, 1 e 2 m rispettivamente). la presenza del relitto (a) è chiara solo con la risoluzione massima (dimensioni della figura 30 x 10 m). similar to an aerial photograph, which is viewed realtime on a computer monitor in the towing vessel. typically, the side scan sonar searches a swath that is 60 to 160 feet wide at about 2 miles per hour, although other ranges can be used depending upon the size of the target. these systems represent a fundamental key for target detection, because of their ability to evaluate roughness variations that correspond to change in materials. side scan systems use a sonar device that emits fan-shaped pulses down toward the seafloor across a wide angle perpendicular to the path of the sensor through the water. the transducer may be towed from a surface vessel or submarine, or mounted onto the ship's hull. the acoustic intensity of reflections from the seafloor is recorded on cross-track slices. finally, records are “mosaiced”, in order to obtain a plan view of the bottom that represents a “sonic picture” of the seafloor. this technique appears to be the most suitable for target detection of outcropping objects, although results should not be considered significantly different from multibeam data in very shallow waters. 2.2 buried targets: magnetic survey magnetically susceptible bodies can be easily detected with the use of magnetic methods (boyce et al., 2004), although several problems may arise from the presence of anthropic objects such as pipelines, anchors, chains, etc. the magnetic survey has been carried out in a 10x10 meters grid. data acquisition was performed by using a “seaspy” magnetometer (marine magnetics corporation), with a sensor based on the overhauser effect, with 0.2 nt of accuracy and 0.01 nt of sensitivity. the analytic signal (n a b i g h i a n , 1972; roest et al., 1992) can help in the identification of the horizontal boundary and in the determination of exact location of the magnetic sources (fig. 2). the analytic signal, a(x,y), is calculated by taking the square root of the sum of the squares of each of the three directional first derivatives of the magnetic field, t, as follows: |a(x,y)|=( (dt/dx) 2+ (dt/dy) 2+ (dt/dz)2)1/2 the resulting shape of the analytic signal is independent of the orientation of the magnetization of the source and is centered on the causative body. this has the effect of transforming the shape of the magnetic anomaly from any magnetic inclination to one positive body centered on the anomaly. the used function is based on the u.s.g.s. program pdepth 35integrated geophysical investigation ... (phillips, 1997), through the calculation of the hilbert transform. in the absence of high-frequency noise, local peaks are interpreted as corners of source, and provide a high accurate horizontal location of the magnetic sources. buried metallic objects are clearly identified by means of magnetic surveys, but problems in data acquisition may arise over volcanic areas, particularly in deep waters. 2.3 buried targets: high-resolution seismic survey typical properties of embedded objects are: 1) small dimensions and unknown positions within large survey areas; 2) very weak reflectors due to the attenuation of the overburden sediment material; 3) small differences in the properties of the surrounding sediment, if the object is made of wood and filled with water. a wide range of marine single channel seismic systems are used for high resolution prospecting. their main differences are about the nature of the source (mainly its frequency and amplitude). acknowledged setbacks related to the use of common linear acoustical systems are: 1) low frequencies are required to penetrate the sediment; 2) wide beam width with a large footprint, high reverberation level and low horizontal resolution; 3) have long and ringing transmitter signals and low vertical resolutions and 4) small system bandwidth and low ping rates in the detection of small and weak reflectors. high frequency seismic profilers (chirp, subbottom, etc.) are not significantly penetrative through sand, while sparker systems do not seem to be sufficiently resolutive because of the wide angle of the source fig. 2 a) shaded relief of the multibeam data (grey scaled image) with overlapped (b) the analytic signal coming from the magnetic data (contour map). magnetic boundary are intense around the shipwreck. a) rilievo ombreggiato (in scala di grigio) dei dati multibeam e (b) mappa a curve di livello del segnale analitico calcolato dalle anomalie magnetiche residue del campo misurato. 36 beam. in this sense, boomer systems represent the best technique to ensure both penetration and resolution. the sparker, consisting of an electrode array powered by a capacitor bank of a few hundred joules, has been widely employed for studies on the continental shelf. an electromagnetic source or boomer was developed during the early 1960’s (edgerton and hayward, 1964). seismic energy comes from the sudden separation of an aluminium plate from a flat copper coil embedded in a hard epoxy resin. the plate is initially held against the coil. during the rapid discharge of a bank of capacitors through the coil, eddy currents are induced in the aluminium plate causing a rapid repulsion and the creation of a cavitation volume in the water. the first pressure pulse is due to the rapid outward acceleration of the aluminium plate, followed by a pulse from the implosion of the cavitation volume. boomers (like the eg&g uniboom) with pulse lengths of 0.1-0.2 ms have been developed for reflection profiling in water depths of a few meters. these are able to resolve reflectors less than 0.3 m apart in near-shore sediments (simpkin and davis,1993). sparker and boomer systems have different radiation diagrams: perfect cylindrical symmetry for boomer and very asymmetric and with large angle in the transverse (with respect to navigation) direction for sparker. boomer and uniboom, which we have used for this survey, are both energy limited to 0.5-1kj, while sparker is limited to 3-5kj. results are reported in fig. 3.the eco signals have been acquired and post processed applying band-pass digital filter in order to enhance signal/noise ratio. this operation has been performed by mean the powerful hardware/software platform dseismic. (corradi, 2004) . parametric acoustic systems (like ses 1000 and ses 2000 of innomar technologie gmbh of rostock) represent a new frontier for such problems. they are particularly suitable because of the small footprint, low reverberation level and high horizontal resolution, short transmitting signals without ringing and high vertical resolutions, plus they are able to detect small and weak reflectors 2.4 buried targets: resistivity survey marine geoelectrical measurements coupled with swath bathymetry represent an innovative technique for archaeological target detection in very shallow water and a valid alternative to seismic-acoustic prospection, particularly in marine sectors with sand at the seabed. although this technique is not yet commonly used in geophysical marine exploration, the initial results of our surveys seem to be promising both for archaeological target detection and sedimentological purposes. this method can be used to outline both conductive and resistive bodies, like metallic and wooden objects, respectively. resistivity data acquisition was carried out using a georesistivimeter iris-syscal pro system, with a 2 meter horizontally spaced multielectrode marine cable, and with the use of the sysmar software. the reciprocal wenner array was adopted along a profile that reached a depth of about 8 m below sea level. data inversion was obtained by using the res2dinv algorithm (loke and barker, 1996; loke and dahlin, 2002). the occurrence of the shipwreck is strongly defined in the conductivity map showed in fig. 4 that reports the geoelectrical tomography under a bathymetric map. 3. discussion and conclusions on the basis of the literature the initial approach toward the choice of the most appropriate geophysical technique for marine detection of archaeological tarfig. 3 high resolution seismo-acoustic methods are difficult to use in < 5 metres of water column especially over coarse grained sediments (sands, gravels etc.). most problems are due to strong reflectivity of coarse sediments, ringing of the seismic source, multiple or ghost reflections etc.. all these factors affect both spatial (horizontal) and vertical resolution which must be submetric in case of archaeological targets (belfer et al., 1998; papatheodorou et al., 2005). results of the boomer technique in the study area: lateral changes in amplitude and phase seismic signal in correspondence of the wreck are present (a and b). although lateral variations are clearly visible, it is difficult to relate them to the presence of archaeological bodies, but boomer data may be a valid support for other techniques. i rilievi sismo-acustici in acque basse (>5 m) e in presenza di fondali sabbiosi e ghiaiosi sono estremamente complessi. la riflettività dei sedimenti grossolani, la riverberazione del segnale sismico-acustico, le generazione di riflessioni multiple e i segnali diretti compromettono la qualità dell’acquisizione e il grado di risoluzione (verticale e orizzontale) necessario per evidenziarei target archeologici (belfer et al., 1998; papatheodorou et al., 2005). i risultati ottenuti con la sorgente boomer evidenziano variazioni laterali dell’ampiezza e della fase del segnale sismico in corrispondenza del relitto (a e b), ma non è altrettanto chiara la relazione fra il target e il tipo di anomalia del segnale sismico da esso generato. l’utilizzo di un sistema boomer, pertanto, è consigliabile come integrazione e supporto ad altre tecniche di prospezione. s. passaro et al. 37 gets can be (carefully) traced before hand. results are summarized in table 1 and refer to a mechanism where reciprocal exclusion may provide helpful indications about the adoption of specific surveys. clearly, this scheme assumes a basic knowledge of the area of interest, in terms of average depths of the water column, sediments and geology of the seafloor, presence of possible anthropic targets, etc. reliability of geophysical data is enhanced when a drilling stratigraphy is available for geophysical data calibration. outcropping bodies are well detected by multibeam swath bathymetry when footprint dimension allows horizontal resolution that can be considered equivalent to side scan sonar mapping. nonetheless, side scan sonar systems are to be considered as the essential and more reliable tool for outcropping target recovery. in regards to buried targets, seismic sources (often used in this kind of investigation) should be chosen carefully, according to the indications provided by local sediments and water column depth. in case of fine grained sediments, such as clays or silts (e.g. lakes), the use of frequency-modulated (“chirp”) or fixed frequency subbottom profilers is recommended, while in the case of coarse grained sediments, boomer or parametric systems are more appropriate. in fig. 4 marine geoelectrical measurements coupled with swath bathymetry represent an innovative technique for archaeological target detection in very shallow water and a valid alternative to the seismic-acoustic prospecting, particularly in marine sectors with sand at the seabed. although this technique is not yet commonly used in geophysical marine exploration and needs more refining, preliminary results of our survey seem to be promising for both archaeological target detection and sedimentological purposes. in this picture a 3d conductivity map is represented, which clearly shows the occurrence of an anomaly in correspondence of the shipwreck (imagine on the top). this technique can be easily used in shallow water, while it might be more complicated in other cases because of limitations imposed by cable length. l’acquisizione di dati geoelettrici in ambiente marino integrati con rilievi batimetrici di altissima risoluzione, è una metodica innovativa per l’identificazione di target archeologici in acque basse e rappresenta una possibile alternativa alle prospezioni sismoacustiche, specialmente in presenza di fondali sabbiosi. sebbene in letteratura manchino riferimenti a tali tecniche esplorative in mare e nonostante tali metodiche siano ancora a carattere sperimentale, i risultati preliminari delle indagini effettuate lungo il litorale di agropoli sottolineano come tali procedure siano promettenti sia in campo archeologico che sedimentologico-stratigrafico. in figura è riportata la mappa 3d della conduttività, dove è chiaramente visibile l’anomalia generata dal relitto (immagine in alto). la geoelettrica marina è facilmente utilizzabile in contesti di acqua bassa, mentre in acque profonde il suo uso non è agevole per le limitazioni imposte dalla lunghezza del cavo richiesto. table 1 summary of investigation methods to be used for target detection (see text for details) sintesi dei sistemi utilizzabili per l’identificazione di target archeologici in acque basse. investigation use encouraged use discouraged technique characteristics in presence of: in presence of: outcropping bodies and less more than 50 metres high resolution mbes frequencies (f): than 50 metres of water of water column depth 500-250 khz column depth (use side scan sonar) less than 50 metres of water side scan sonar f of about 400-100 khz outcropping bodies column depth the use of multibeam is equivalent sub-bottom profiler 20 khz > f > 1 khz fine sediments (clays or silts) coarse sediments (sands, gravels) frequency modulated fine sediments coarse sediments (sands, gravels); “chirp” sub-bottom profilers 20 khz > f > 1 khz (clays or silts) poor or null penetration 35-45 khz dual frequency (primary frequency) coarse and fine sedimentsparametric sub-bottom 1-10 khz (secondary frequency) uniboom frequency: 0.2-1 khz fine sediments (traditional, chirp or energy: 0.5-1 kj coarse sediments parametric systems preferable) gradiometers or highly susceptive targets magnetic magnetometers with expected; clearance from volcanic sectors and/or sensitivity of 0.1 nt magnetometer to seafloor not highly anthropized sectorsexceeding 20-30 m magnetic gradiometers or highly susceptive targets volcanic sectors and/or magnetometers expected highly anthropized sectors geoelectric 5 metres step cable investigation depth range of 0-7m investigation depth>10m integrated geophysical investigation ... 38 addition, in situations of water depth of less than five metres, the adoption of geoelectrical measurements becomes preferable. magnetic surveys may help to detect both metallic and wooden targets, especially when susceptive bodies (like anchors or armaments) are present, but may be inadequate where low signal to noise ratios are induced, especially in the presence of a volcanic (e.g. lava flows) seafloor or in industrial (e.g. harbours) settings. acknowledgments the authors are grateful to m. fedi and g. de alteriis for their useful comments and reviews that helped us to greatly improve this manuscript references belfer i., bruner i., keydar s., kravtsov a., landa e. 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(1993) for seismic profiling in very shallow water, a novel receiver , sea technology, 34 (9), pp. 21–28. ms. ricevuto il 3 ottobre 2008 testo definitivo ricevuto il 16 marzo 2009 ms. received: october 3, 2008 final text received: marchy 16, 2009 s. passaro et al. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 20%) /calrgbprofile (srgb iec61966-2.1) /calcmykprofile (u.s. web coated \050swop\051 v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false 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difesa del suolo, servizio geologico d’italia, e svolto a roma nel marzo del 2007 presso la sede dell’apat. ll dibattito scientifico è scaturito con la pubblicazione del foglio geologico 557 cagliari (distribuito a partire da novembre 2006) dove i depositi fossiliferi marini di età tirreniana (125 ka) risultavano ringiovaniti all’olocene. queste note vogliono evidenziare come la differenza tra l’attribuzione cronologica tirreniana e quella olocenica implichi una serie di ricadute e problematiche non discusse né approfondite nella legenda della carta. qui vengono riassuntivamente esposti i motivi per i quali, questi depositi fossili non possono essersi sedimentati nel corso dell’ultima trasgressione, quella olocenica. 1.1 dati sui depositi fossiliferi di is arenas l’area costiera in oggetto occupa con i “depositi di spiaggia e dei cordoni dunari antichi” fossiliferi una vasta estensione del foglio 557 (fig. 1). numerosi sono stati i lavori pubblicati su riviste nazionali ed internazionali che hanno preso in considerazione questi depositi fossiliferi marini i depositi tirreniani nell’area di montelargius (cagliari) fabrizio antonioli via a. millos 37, roma fig. 1 l’area costiera nella quale si trovano i depositi di is arenas. viene evidenziata da una freccia la massima distanza (5,2 km) dall’attuale linea di riva. 94 circostanti gli stagni di quartu e di montelargius, area denominata “is arenas”. tra tutti spicca per incisività, chiarezza e contenuti, quello firmato da ulzega e hearty (1986) e da hearty, 1986. gli autori hanno descritto i depositi e li hanno datati con tecniche incrociate (u\th e aminostratigrafie). tutte le analisi concordano nell’assegnare i depositi di is arenas all’ultimo interglaciale (mis 5.5, 125 ka). si rimanda per qualsiasi dettaglio ai lavori in oggetto, di cui viene riportata la tabella (fig. 2). sempre per l’area di is arenas gli autori riportano anche il ritrovamento di strombus bubonius. per meglio dettagliare questa ultima informazione, è stato contattato il prof. ulzega e da lui abbiamo avuto conferma sia del ritrovamento (lo strombus b. è ancora conservato presso l’archivio dell’università) che della quota (+ 4 metri) di rinvenimento, le coordinate sono 39°13’28’’59n, 09°10’36’’ 21e. tutti i lavori pubblicati successivamente (vedi anche bibliografia contenuta nelle note illustrative della carta) concordano con questa interpretazione. non è questo l’unico ritrovamento di fauna calda: alcuni strombus b., rinvenuti nell’area a quote intono al l.m. vengono citati nelle note illustrative e interpretati dagli autori della carta come “rimaneggiati”. 1.2 variazioni di livello del mare nel tirreno ed in sardegna molti sono i lavori che illustrano i meccanismi di risalita del livello dei mari italiani nel corso dell’ultimo ciclo climatico (alessio et al., 1996; antonioli e silenzi 1998; antonioli e leoni 1998; antonioli, 2000; lambeck e bard 2000; lambeck e chappel, 2001; bard et al., 2002; antonioli 2004; lambeck et al. 2004 a, b) tutti concordano che nelle aree considerate stabili il livello del mare più alto mai registrato da 100 ka sia quello odierno. depositi olocenici vengono descritti e rinvenuti fino a 4 metri sopra il livello del mare solamente in aree in attuale sollevamento (antonioli et al., 2003; antonioli et al., 2004; antonioliet all., 2006, ferranti et al., 2007) o fino a qualche metro sotto il livello del mare in aree subsidenti sulla costa del ne (lambeck et al., 2004a). il prof. paolo orrù, direttore del rilevamento dell’area marina del foglio cagliari, nelle note illustrative riporta il risultato dell’analisi di 3 sondaggi carotati a meno di 2 km dai depositi di is arenas: le radiodatazioni sui fossili lagunari campionati nei sondaggi (orrù et al., 2004), se paragonate con le stesse quote della curva di risalita calcolata per cagliari (lambeck et al., 2004a) evidenziano stabilità tettonica per gli ultimi 10 ka bp. infine una recente ricerca (antonioli et al., 2007) prende in considerazione numerosi markers archeologici oggi sommersi nel mare in molte aree della sardegna, prendendo in esame anche siti molto vicini all’area di is arenas. questi dati archeologici confermano la sostanziale stabilità delle coste meridionali sarde e delle lagune circostanti l’area di cagliari durante gli ultimi 2700 anni. uno dei siti studiati nel lavoro si trova nella laguna di santa gilla (meno di 2 km da is arenas) ed indica molto chiaramente stabilità tettonica. fig. 2 tabella con le datazioni di ulzega e hearty, 2006. 95 1.3 considerazioni i depositi fossiliferi (spiaggia sommersa) di is arenas, raggiungono una quota di circa 4.5 metri sul livello del mare mentre la distanza dalla costa degli stessi depositi arriva a 5,2 km (fig. 1). una quota così alta ed una distanza così rilevante dall’attuale linea di riva sono facilmente spiegabili solo con un livello del mare di 6 metri più alto (l a m b e c k et al., 2004c), come occorso nel mediterraneo circa 125 ka bp. situazioni molto simili a questa sono descritte per l’italia in ferranti et al., 2006, dove vengono illustrati 244 siti di età tirreniana. la quota di depositi tirreniani in sardegna (fig. 3) varia da 2 a 10.5 metri. nel foglio 557 cagliari, i sedimenti fossiliferi di is arenas vengono attribuiti alla trasgressione olocenica. per giustificarne la quota e la distanza dalla costa si potrebbero invocare grandiosi fenomeni di tsunami, ma la sedimentologia (spiaggia sommersa) dei depositi di is arenas esclude questa possibilità. nel corso della discussione il responsabile della stratigrafia del quaternario del foglio 557 (prof. mauro coltorti) ha giustificato la quota dei depositi fossiliferi correlandola ad un recente sollevamento dell’area costiera. anche questa eventualità sembra poco verosimile, sia per motivi topografici che per motivi geodinamici. alla luce infatti del profilo batimetrico del prolungamento a mare dell’area costiera di is arenas e dei tassi di risalita del mare negli ultimi 6 ka (lambeck et al., 2004a), anche con (improbabili) sollevamenti di 2-3 mm\anno la linea di costa non potrebbe trovarsi oggi a più di 5 km di distanza dalla costa. da un punto di vista geodinamico molti sono i motivi che escludono un sollevamento occorso durante l’olocene: fig. 3 quota della massima trasgressione tirreniana in sardegna da ferranti et al., 2006. 96 • assenza di faglie attive presenti sia nelle note illustrative che nel territorio costiero compreso tra is arenas e cala mosca dove affiorano a circa 4 metri s.l.m. i depositi fossiliferi interpretati da gignoux (1913) come tirreniani; • assenza di eventi sismotettonici storici nell’area costiera di cagliari; • assenza di terrazzi sollevati o dei presunti depositi marini del pleistocene superiore; • assenza di riscontri di sollevamento su qualsiasi dato strumentale, sia osservando il mareografo di cagliari (psmsl) che numerosi lavori che analizzano dati gps (caporali et al., 2003; serpelloni et al., 2006). • presenza del solco di battente attuale, contrariamente a quanto avviene su litologie carbonatiche in aree in sollevamento (antonioli et al., 2003) vedi fig. 4. gli autori del foglio cagliari hanno effettuato sui molluschi fossili di is arenas numerose datazioni utilizzando tecniche di radiocarbonio; tutte queste datazioni indicano inequivocabilmente che i depositi non sono olocenici. la presenza di depositi marini olocenici rinvenuti in sondaggi prossimi ad is arenas e datati con 14c (orrù et al., 2004) e archeologici sommersi, di sicura attribuzione cronologica (solinas 1997, solinas orrù 2004, antonioli et al., 2007), markers archeologici che si trovano alla quota eustatica alla quale si devono trovare (fig. 5), esclude sollevamenti nel corso dell’olocene. conclusioni come ampiamente discusso non c’è un solo dato che possa fare pensare che i depositi marini fossili di is arenas possano essere ascritti all’olocene. prassi consolidata è quella che i fogli geologici riportino un aggiornato riassunto di quanto scientificamente noto e pubblicato fino al momento della edizione della carta stessa. questo non è accaduto per il foglio cagliari, nella carta infatti è stata scelta una nuova interpretazione (fig. 6a) assai ardita e non suffragata da dati, contro il parere di tutta la bibliografia esistente (fig. 6b). come affermato dal prof. corselli nel corso del dibattito, si attende che gli autori della carta possano inviare a nature una nota che dimostri il sollevamento olocenico della sardegna meridionale, o, alternativamente, che il servizio geologico riveda quello che appare come una interpretazione personale degli autori. ringraziamenti si ringrazia il dr. leone serva per la grande disponibilità dimostrata e l’organizzazione dell’incontro. fig. 4 il solco di battente attuale scolpito sui carbonati del m. sant’elia (cagliari) 97 references alessio m., allegri l., antonioli f., belluomini g., improta s., manfra l., preite m. 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(1986) -geomorphology, stratigraphy and geochronology of late quaternary marine deposits in sardinia. zeitschrift für geomorphologie n. f., suppl. bd. 62, 119-129. amq29(2) 1 vai 113-121 nag.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 29 (2), 2016, 113 121 ancient dna studies stefania vai, martina lari, david caramelli dipartimento di biologia, università degli studi di firenze, firenze, italy corresponding author: s. vai <stefania.vai@unifi.it> abstract: about three decades of scientific research confirmed ancient dna as a powerful tool for anthropology, paleontology, molecular evolution, conservation genetics and forensics. a rapid evolution of the methodological approaches in the last ten years led to an important increase of data related both to the number of samples and to the informative genetic markers. paleogenetics analysis has been applied to a wide spectrum of samples, answering to different kind of scientific and cultural questions. in this review, ancient dna characteristics and methodological approaches are presented as well as recent results obtained from samples of bacteria, plants, animals, with a particular focus on the newest discoveries about the homo genus. keywords: ancient dna, adna, paleogenetics 1. introduction the first data obtained from ancient dna samples were published in 1984, when higuchi et al. (1984) presented the results obtained from a tissue samples of a museum specimen of the quagga, a zebra-like species (equus quagga) extinct one hundred years before. in 1985 svante pääbo published the recovering of genetic material from an egyptian mummy (pääbo, 1985). the first results obtained from bone tissue date back to 1989 (hagelberg et al., 1989). in thirty years from these first attempts, huge innovations in methodology, signed by the polymerase chain reaction (pcr) first and the next generation sequencing (ngs) later, allowed researchers to understand the characteristics of the ancient dna, to better recognize it from possible modern dna contaminations and to obtain a large amount of data useful for different kinds of applications. after the first work by higuchi where 299 nucleotides of the mitochondrial genome of the quagga were sequenced, data for the whole nuclear genome of this species were obtained (jonsson et al., 2014). after the first attempt by pääbo, the complexity of recovering authentic ancient molecular data from human remains was better defined and sophisticated experimental procedures and bioinformatics tools were developed in order to obtain reliable results. 2. ancient dna, definition and characteristics despite its name, ancient dna (adna) has no age. this expression defines degraded dna, and degradation of genetic material starts immediately after the dead of the organism or when a biological trace is left in the environment. for this reason, both paleontological and historical samples and more recent traces analyzed in forensic contexts can be considered as adna. the starting material includes samples such as bones, hair, mummified tissues, coprolites, sediments, vegetable remains, and the temporal limits reached so far are about 400,000 years for samples recovered in caves from temperate regions (meyer et al., 2014) and about 700,000 years for samples preserved in permafrost (orlando et al., 2013). adna has particular characteristics due to the degradation of the genetic material mainly occurring by hydrolysis and oxidation led by factors such as temperature, humidity and ph. often, when the genetic material extracted from a degraded sample is analyzed, the majority of the dna can be referred to a microbial origin and only a little percentage belongs to the organism from which the sample comes (fig. 1). dna degradation determines not only the loss of the genetic material, but also the high fragmentation of the surviving component fig. 1 graphical representation of the dna content of an ancient sample (data unpublished). work presented during the aiqua scientific conferences "waiting for the nagoya inqua xix congress", held in florence, june 18 19, 2015 114 vai s. et al. fig. 2. misincorporation pattern for a human sample dated 4700 bp (data unpublished). the four upper mini-plots show the base frequency outside and in the read (the open grey box corresponds to the read). the bottom plots are the positions' specific substitutions from the 5" (left) and the 3" end (right). the c>t substitutions are in red, the g>a substitutions are in blue. the estimation was performed using mapdamage 2.0 (ginolhac et al., 2011). 115 ancient dna studies that is usually characterized by dna fragments of short length (krause et al., 2010a). another typical form of degradation that characterizes the adna is the deamination of the cytosine, that is translated in a misincorporation event during the determination of the dna sequence where an original c (cytosine) is converted in t (thymine), or an original g (guanine) is substituted by a a (adenine) when the damage involves the opposite dna strand (brotherton et al., 2007). these misincorporations occur on the adna molecules following a particular pattern: their frequency increases at the ends of the molecules (briggs et al., 2007) (fig. 2). these characteristics determine the need of a specific experimental workflow designed for recovering highly degraded molecules, but represent in the meantime an informative source that allow to discriminate between authentic ancient endogenous dna from possible modern contaminants. 3. methods for the study of adna specific criteria have been developed for working with adna. a first important advantage is provided by an appropriate behavior in sample recovering in order to avoid the contamination during handling of the remain wearing sterile gloves, masks and special or disposable clothes (pilli et al., 2013). the laboratory where the molecular analysis is performed, has to be exclusively dedicated to adna with a physical separation between the pre-amplification and the post-amplification sections and devices for sterilizing the working areas. some years ago, the only methodological approach available for adna studies was based on pcr, cloning and sanger sequencing. following this strategy, a target dna region is selected and amplified by pcr, obtaining an exponential increase of the number of molecules of interest. the pcr product is cloned using a plasmid vector and bacterial cells. isolating and reproducing single molecules of the pcr product in the bacterial cells, it is possible to sequence independently each amplicon that consists on a bacterial colony carrying several copies of a single original dna molecule obtained by pcr. in this way the sequence of numerous molecules selected by pcr is determined, giving the possibility to observe the possible presence of multiple biological sources and of misincorporations (fulton and stiller, 2012). using this methodological approach, it is necessary to have a prior knowledge of the target sequence in order to design the primers needed for the amplification and the whole target sequence (primers annealing regions included) have to be preserved intact in the ancient sample. furthermore a minimum fragment length of about 60bp is required for the molecules to be recovered by pcr. this requirements represent a limitation for highly degraded samples with really short dna fragments. the so-called golden criteria were developed to assess the authenticity of the results obtained by pcr (cooper and poinar, 2000). with the more recent ngs approach, universal adapters are ligated to the dna fragment, independently from their sequence or length (briggs and heyn, 2012). every kind of dna molecule can be potentially recovered, without modifying its original characteristics that can be then used for assessing its authenticity as ancient. barcodes can be added to the dna fragments together with the adapters, creating the so-called dna library. with this strategy is possible to process numerous samples in parallel producing a large amount of sequence data, even whole genomes, and consequently more information. since the endogenous dna could be represented in a small percentage in the sample, usually the ngs approach is flanked by a strategy of target enrichment using baits complementary to the sequences of interest, in order to increase their relative amount. the hybridization between baits and target molecules is usually performed in solution with a bead-based capture approach (carpenter et al., 2013; maricic et al., 2010). the sequencing of the whole library (shotgun approach) or of the enriched one produces a big amount of data and specific bioinformatics pipelines have been developed for handling them taking into account the characteristic of the adna. software for filtering the data according to quality and length such as fastqprocessing (kircher, 2012), mapping and assembling procedures as mia (green et al., 2008), specific procedures for misincorporation pattern analysis (ginolhac et al., 2011) and contamination estimation (fu et al., 2013), as well as more complete pipelines like paleomix (schubert et al., 2014) or schmutzi (renaud et al., 2015) are available. guidelines for ngs work on ancient dna were also proposed (knapp et al., 2015). 4. ancient dna studies adna data represents an informative source that have application in different fields. the range of possible starting material is wide, and the questions that can receive a contribution from the paleogenetics involve topics related for example to the study of evolution and phylogenesis contributing to anthropological, archaeozoological and archaeobotanical studies and of archaeology, cultural heritage and fauna and flora conservation. adna studies on bacteria as previously described, most of the dna preserved in an ancient sample usually belongs to microorganisms. characterization of the microbial diversity in horse bones from a time span between 200 and 13,000 years ago, consisted in site-specific microbial profiles that allow to characterize the environment from which the samples were recovered (der sarkissian et al. 2014). however, the majority of data belonged to a recent bacterial colonization of the bones. this observation implies that the characterization of authentic ancient microbial remains is a complex process that requires specific methodological devices. in the last years, a particular interest was focused on the analysis of the oral microbiota in human samples, in order to reconstruct its possible variations during time linked to specific subsistence and cultural shifts occurred in human history. the starting material for this kind of studies is the dental calculus (plaque), that showed to preserve a record of the microorganism composition of the oral cavity, including bacteria involved in 116 local and systemic diseases, as well as molecular information about host immunity and diet (warinner et al., 2014; weyrich et al., 2015). the neolithic revolution, began about 10,000 years ago, with the shift toward a carbohydrate-rich diet, and the recent employment of industrial processed sugar and flour started around 1850, determined major changes in the microbial oral community. disease-associated configuration remained constant between neolithic and medieval times, then the cariogenic bacteria became dominant with the industrial revolution, with a general less diverse microbial profile in modern populations (adler et al., 2013). another research field is about the reconstruction of ancient pathogens’ genomes in order to clarify the phylogenesis of such species, to understand the relationship between different strains, and to identify possible polymorphisms related to virulence. the whole genome of mycobacterium leprae was determined from medieval leprosy cases and its comparison with modern strains revealed remarkable genomic conservation during time (schuenemann et al., 2013). differently, the analysis of whole genomes of the medieval strain of yersinia pestis recovered from victims of the black death revealed that this variant of the bacterium may no longer exists, but it is probably ancestral to the modern strains. the epidemiological differences in time seem to be not related to genetic differences, but to other factors such as environment, host susceptibility or vector dynamics (bos et al., 2011; schuenemann et al., 2011). adna studies on plant remains data about adna from vegetable remains are not so numerous, since it is difficult to extract genetic material from ancient plants that often also contain inhibitory substances that interfere with some experimental procedures. despite these difficulties, archaeobotanical samples can provide information about species identification, domestication and evolutive processes. genetic material can be found in different kind of samples: wood, fruits, leaves, seeds and pollen in archaeological or herbarium specimens. dna of vegetable origin can be preserved also in feces (wood et al., 2012) and dental calculus (weyrich et al., 2015) providing information about diet. also sediments are a source for plant dna revealing the vegetation distinctive of past times even in absence of macrofossil evidences (willerslev et al., 2003). paleoenvironmental studies on sedimentary ancient dna permit to reconstruct the plant cover history and to understand the changes during time due to climate or human activities (pansu et al., 2015). with the same approach, it is possible to attest the presence of domestic plants in sediments, better defining the chronology of the neolithic transition (smith et al., 2015). comparing genetic data between different wild and domestic forms, it is possible to identify the original variants from which the domestication occurred, to follow routes of diffusion related with the anthropic exploitation and to give information about both the vegetal and human history. it is also possible to identify genetic loci under selection during domestication for adaptation to climatic and cultural contexts, such as drought and sugar content (allaby et al., 2014; allaby et al., 2015; da fonseca et al., 2015; palmer et al., 2012). adna studies on animals genomes of extinct species is a powerful tool to understand their phylogenetic relationships with extant forms. many paleogenomics studies have been conducted on faunal remains. the nuclear genome of several woolly mammoths was sequenced, defining with higher resolution the phylogenetic tree of the elephantids. some differences with functional effects were found between mammoth and elephant and in some cases variants were probably positively selected in the mammoth lineage. intra-population differences, that were not evident from the fossil records, were also highlighted (miller et al., 2008). the most ancient genome determined so far is from a horse sample preserved in permafrost dated between 560-780 thousand years bp. by comparing this sequence with those of other ancient and modern horse and donkey samples, the most recent common ancestor of the genus equus was dated to 4.0-4.5 million years bp. interestingly, multiple population size fluctuations related to climate changes have been attested in the history of this taxa, as well as particular genomic regions have been found to be possibly selected during domestication (orlando et al., 2013). about domestication process, several researches have been conducted in order to identify the area where it took place, the possible routes followed by the spread of the livestock and the possible admixture with wild local forms. while the history of the domestication of sheep and goat is rather simple to be reconstructed since the wild forms were limited to the fertile crescent before neolithic, the dynamics related to the domestication of cattle and pig could be more complex because the wild forms of bos taurus primigenius and sus scrofa were spread in a wider area. ancient and modern dna data collected from europe, western anatolia and iran, shown that the domestication of cattle occurred as a single process in the near east in the 9th millennium bc. with the neolithic transition, the domestic form spread into europe with no significant interbreeding with the local wild individuals (scheu et al., 2015) even if some haplotype sharing between preand post-neolithic samples in southern europe suggests a possible contribution from the wild local forms in particular areas (bejapereira et al., 2006; lari et al., 2011; mona et al., 2010). several studies on ancient and modern dna were conducted in order to understand the dynamics related to the swine domestication. a phylogeographic approach suggested the origin of the domestic form in the near east, its spread in europe during the neolithic diffusion, then a local domestication of the european wild boar. a later replacement of the eastern lineages by the european ones occurred not only in europe but also in asia minor during the bronze age (larson et al., 2007; ottoni et al., 2013). a recent contribution demonstrated that also natural population dynamics, occurred independently of domestication, can determine the variation in frequency and distribution of such genetic lineages. a so -called near eastern haplotype, previously considered as marker of the neolithization wave from near east, was found in italian samples two thousand years before the arrival of the neolithic culture in that area (vai et al., 2015). this example shows that the reconstructions of vai s. et al. past events are always open to new developments as new samples are analyzed covering new geographical areas and new chronological periods, as well as more genetic markers are considered. adna studies on genus homo particular interest focused on the study of human species, in order to clarify the relationships between different forms that in some cases shared the same geographical areas in the same period, such as neandertals and early anatomically modern humans (emhs). genetic variation of neandertals has been explored in several studies, starting with the methodological approach based on pcr for studying particular loci followed by the sequencing of the whole genome by ngs. genetic discontinuity between this extinct human form and extant and ancient modern humans was already attested analyzing a portion of the mitochondrion (mtdna) (krings et al., 2000; caramelli et al., 2003) and was confirmed when the whole mtdna genome was determined in 2008, confirming that the neandertal mtdna falls outside the variation of modern humans with an estimation of the divergence time around 660,000 years ago (green et al., 2008). analyzing more neandertal individuals, it was possible to identify a possible genetic structure at intra-population level, probably related with the geographical and/or temporal distribution of the samples, with a general low mtdna diversity that may reflect a low effective population size (briggs et al., 2009). in addition, some nuclear genes were studied, since they are involved in phenotypic traits that could highlight possible differences between modern humans and neandertal. for example, a private variant of the mc1r gene was found in two neandertal remains, coding for pale skin color and red hair (laluezafox et al., 2007), representing an example of convergent evolution for adaptation to environments with low solar radiation. with the ngs approach, it was then possible to obtain the whole nuclear genome from neandertal specimens, and to find that a portion around 1-4% of the genome of the extant inhabitants of eurasia is shared with neandertals. the most parsimonious explanations for this sharing are two: i) the neandertals exchanged genes with the ancestors of all non-africans or ii) the presence of an old substructure in africa, whose traces persisted both in the neandertal lineage and in the modern human one (green et al., 2010). recently, the genome of a modern human sample, found in romania and dated to 39,000-42,000 years ago, carrying morphological traits that could indicate admixture with neandertals, was determined. 6-9% of the genome of this individual showed neandertal ancestry compatible with an admixture occurred four to six generation back (fu et al., 2015). a new human species was identified in 2010 thanks to adna analysis: samples from the denisova cave, in southern siberia, dated to 50,300-62,200 years ago, showed a genetic variation that falls outside the range of both modern humans and neandertals. according to the mitochondrial genome, the denisova repre 117 fig. 3 schematic reconstruction of the possible gene flow events occurred between human lineages during late pleistocene (data from prüfer et al., 2014). ancient dna studies sents a human lineage that diverged about 1 million years ago from the branch that carried to h. sapiens and neandertal (krause et al., 2010b). data from the nuclear genome showed that probably denisovans contributed to the 4-6% of the genome of present-day melanesians (reich et al., 2010). the phylogenetic tree reconstructed using nuclear data place denisovans as sister group of neandertals. the difference between the phylogenesis obtained from mitochondrial and nuclear genomes can be explained considering that the mtdna is only maternally inherited, while the nuclear genome carries information from both parents. for this reason the two genetic markers can tell different population histories. the nuclear data from human forms closely related to modern humans represent an important informative source also for understanding which genetic variants characterize the homo sapiens lineage becoming fixed after its separation from the ancestors of neandertals and denisovans. genes that showed derived variants only in the modern humans are involved with brain function and nervous system development, as well as the physiology of skin and eye and dental morphology (meyer et al., 2012; prufer et al., 2014). thanks to the reconstructed ancient genomes, it was possible to recognize several gene flow events, with general low extent or at least with low effect on the extant populations, that have involved neandertals, denisovans and emhs during their coexistence in eurasia during late pleistocene (fig. 3). the research on past human forms is still developing, since new specimens are discovered. a new protagonist of the human history provided genetic information to be added to the already complex reconstruction, representing also the most ancient sample from temperate environment that yielded endogenous dna. the sample, attributed to homo heidelbergensis according to morphology but with some neandertal-derived characteristics, was date over 300,000 years ago. the already determined mitochondrial genome showed to be closely related to the lineage of denisovans, increasing the expectation for the next nuclear data (meyer et al., 2014). adna data gave a big contribution also for understanding the more recent population history of homo sapiens, especially for europe. the presence of emhs in europe is attested since 45,000 bp and particular climatic and cultural changes characterized the population dynamics during time: last glacial maximum, mesolithic with mobile groups and neolithic transition with the appearance of a sedentary lifestyle, copper, bronze and iron ages with the emergence of complex societies. with the ngs technology, several prehistoric human genomes were sequenced, leading to a deeper understanding of such dynamics (olalde and laluezfox, 2015). the first genome to be sequenced was obtained from the the tyrolean iceman (ötzi) lived during the neolithic-copper age transition: the nuclear genomes permitted to determine some phenotypic characteristic and pathogens’ presence as well as information useful for determining the relationship of the sample with modern european, north african and middle eastern popula tions (keller et al., 2012). analyzing other ancient and modern genomes, it was highlighted that most present-day europeans derive from at least three highly differentiated populations: west european hunter-gatherers who probably contributed ancestry to all europeans, upper palaeolithic north eurasians who contributed to europeans and near easterners and early european farmers of near eastern origin with signs also of european huntergatherer ancestry (lazaridis et al., 2014). analysis on 101 ancient humans from eurasia confirmed that the bronze age was a period of big social changes. genomic data showed that large-scale population migrations and replacements occurred, and that probably they are responsible for the major parts of present-day demographic structure in both europe and asia. these migrations could also be related with the spread of indo-european languages hypothesized to be occurred during the early bronze age (allentoft et al., 2015). 5. conclusions for its huge informative power, adna represents a precious resource to support all those disciplines that have the aim to reconstruct past biological events and to use this knowledge for better understand and manage the present variability. major limits are due to different degree of dna preservation in ancient samples, but fast and continuous developing in methodologies, leading to discoveries that were unimaginable three decades ago at 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/hrv (za stvaranje adobe pdf dokumenata najpogodnijih za visokokvalitetni ispis prije tiskanja koristite ove postavke. stvoreni pdf dokumenti mogu se otvoriti acrobat i adobe reader 5.0 i kasnijim verzijama.) /hun 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can be opened with acrobat and adobe reader 5.0 and later.) >> /namespace [ (adobe) (common) (1.0) ] /othernamespaces [ << /asreaderspreads false /cropimagestoframes true /errorcontrol /warnandcontinue /flattenerignorespreadoverrides false /includeguidesgrids false /includenonprinting false /includeslug false /namespace [ (adobe) (indesign) (4.0) ] /omitplacedbitmaps false /omitplacedeps false /omitplacedpdf false /simulateoverprint /legacy >> << /addbleedmarks false /addcolorbars false /addcropmarks false /addpageinfo false /addregmarks false /convertcolors /converttocmyk /destinationprofilename () /destinationprofileselector /documentcmyk /downsample16bitimages true /flattenerpreset << /presetselector /mediumresolution >> /formelements false /generatestructure false /includebookmarks false /includehyperlinks false /includeinteractive false /includelayers false /includeprofiles false /multimediahandling /useobjectsettings /namespace [ (adobe) (creativesuite) (2.0) ] /pdfxoutputintentprofileselector /documentcmyk /preserveediting true /untaggedcmykhandling /leaveuntagged /untaggedrgbhandling /usedocumentprofile /usedocumentbleed false >> ] >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice amq58 sauro last.pub �� � �available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 30 (1), 2017, 75-85 problematic karst fillings of late lower pleistocene age in a cave of the lessini mountains (venetian fore alps, verona)* ugo sauro 1, federico zorzi 2,3 1 museo etnografico di bosco chiesanuova, bosco chiesanuova (vr), italy 2 dipartimento di geoscienze, università di padova, padova, italy 3 ceasc (centro di analisi e servizi per la certificazione), università di padova, padova, italy corresponding author: u. sauro <ugo.sauro@gmail.com> abstract: the excavation of a small cave in the lessini mountains, north of verona, allowed a study of an archaeological complex attributable to the copper age. a fossiliferous breccia, rich in bones of small mammals and birds has been found below the archaeological levels. during 2005 and 2006, the results of paleontological excavations supervised by benedetto sala provided a faunal assemblage correlated to the late biharian. these excavations stimulated a preliminary study of the geological, geomorphological and morphodynamic context of the cave and its surroundings, in order to understand its genetic context. particular attention was paid to the breccia, containing numerous small exotic pebbles, mostly 5-12 mm in diameter. we consider three different hypotheses for the provenience of the exotic pebbles: i) they have been transported and displaced in the area by morphodynamic agents, such as ancient glaciers, and/or watercourses ii) they derive from a completely eroded geological formation, that has been reworked and deposited in this karst trap, iii) they are the result of "ecofacts" caused by birds. all these possible explanations, have some open issues. the “ecofacts” is the most intriguing hypothesis and perhaps the most likely: pebbles could have been transported by birds which use to swallow them to help digestion, then to expel them in boluses or in the excrements. according to this hypothesis, birds could have chosen the cave, or others connected cavities, as nests or as perches. in fact, in the breccia there are bones of large birds of prey, not jet studied. in time, probably, different species of birds have colonized these natural niches, as: vultures, eagles, owls, ravens, etc. so it is very difficult to state what kind of birds could have brought here their preys (the small mammals of which we find the bones), and what kind of birds could have transported the small pebbles. only further excavations and studies will perhaps allow a full clarification of the processes of site formation. keywords: limestone cliffs, cave deposits, exotic pebbles, slivia faunal assemblage, biharian. 1. introduction the excavation of a small cave, called buso della fadanana, in the lessini mountains, north of verona, has allowed a study of an archaeological complex attributable to the copper age (sauro et al., 2007). below the archaeological levels, a fossiliferous breccia has been found, containing a faunal assemblage referable to the late lower pleistocene (late biharian). these excavations stimulated a preliminary study of the geological, geomorphological and morpho-dynamic context in which the cave is located, in order to understand its genetic context. in particular, the purpose of this note is to analyse a problematic aspect of the fossiliferous breccia, namely the presence of numerous rounded pebbles, referable to lithologies not occurring in this karst system and, in some cases, not even in the pre-alpine group of lessini mountains. based on the current state of knowledge, considering the characters of the pebbles, which fall into a strict dimensional range and largely derive from carbonate rocks, the natural morpho-dynamic processes seem unable to explain this occurrence. on the other hand, the available literature on fossil bearing infillings in karst cavities does not illustrate similar situations. it was therefore decided to analyse this aspect of the breccia searching for its meaning in a paleo-environmental reconstruction. it is hoped that further research on this and other similar cavities will contribute to a deeper understanding of the alpine karst environments during the lower pleistocene. 1.1. a complex karst system and its geomorphological context the entrance of the small cave containing the breccia opens on a rock wall at 752 m a.s.l., hanging about 150 m above the valley bottom, in the upper belt of the right slope of the vajo di squaranto, a canyon-like valley in the lessini mountains (venetian fore-alps), in the municipality of bosco chiesanuova, about 20 km north of the town of verona (ne italy). � ____________________________ *u. sauro coordinated this research work; f. zorzi analysed the small pebbles and took part to the discussion. �� � � 76 sauro u. & zorzi f. the east facing wall is about 400 m long and 1080 m high. it consists of jurassic limestone, with the superimposition of two types of rocks: the rosso ammonitico veronese in the upper part and the oolite di san vigilio in the lower part. the anti-dip slope beds, dipping about 10° wsw (figg. 1, 2, 3) are capped by the rosso ammonitico, acting as a caprock. these structural conditions are favorable to the conservation of the rock wall. only in the southern sector, where rosso ammonitico has been eroded, the wall tends to retreat faster and its height is decreasing; the cave is located in this sector. in the rock wall, it is possible to recognize several types of forms (fig. 2). in particular: sub vertical channel, entrance of cave, sub-horizontal notch, developed either above rock cut terraces and in the vertical surfaces, large half-dome niche, recess with mostly vertical development. all these forms are explainable with the geomorphological environment of the rock wall, and in particular with: a) the characters of the different geological formations, b) their tectonic setting, c) the gravity induced processes, d) the karst and weathering processes resulting from the circulation of the karst waters. with regard to point d), the evolution of the underground karst network is an expression of a downward transition from a horizontal circulation (hanging aquifers hosted in dense lithoclastic networks) to an essentially vertical one (diaclastic circulation), from the maiolica to the rosso ammonitico and to the oolite di san vigilio (mégnien, 1966; sauro, 1973, 1974, 1999) (fig. 3). the maiolica is the rock formation above the rosso ammonitico on the top of the ridge. it is strongly fractured and hosts hanging aquifers which lose waters through the main fractures of the rosso ammonitico, feeding a circulation in the oolite di san vigilio. over time, the water forms shaft cavities inside this rock and bedding plain conduits. the lower part of the oolite di san vigilio is massive and contains thin clayey layers, that can favour the formation of local hanging aquifers. the perched water bodies feed many tiny temporary karst springs, which favour a relatively faster weathering of the rock wall just above the impermeable layers and the consequent development of niches and large horizontal notches (figg. 2, 3). where the wall is still capped by the rosso ammonitico, the notches, the half-dome niches, and the recesses are relatively stable forms. instead, in the areas where the rock is strongly fractured and the caprock has been eroded, sub-vertical channels have formed through the collapse of large blocks. in the faster retreating portions of the rock wall, a hanging rock terfig. 1 geological map of the area (from the “carta geologica d’italia”, f° 49 verona, original scale 1:100.000). rw: rock wall described in the paper, ma: maiolica formation, ra: rosso ammonitico formation, osv: oolite di san vigilio formation. � �� � � 77 problematic karst fillings of late lower pleistocene age in a cave of the monti lessini …. � f ig . 2 p a n o ra m a o f th e r o ck w a ll a n d o f its m a in la n d fo rm s (t h e s ca le is in d ic a tiv e ). f ig . 3 s ke tc h o f th e s e ct io n o f th e r o ck w a ll, o f its s tr u ct u ra l se tt in g , h yd ro g e o lo g ic a l ch a ra ct e ri st ic s a n d k a rs t fe a tu re s (t h e s ca le b o th h o ri zo n ta l a n d v e rt ica l i s th e s a m e a n d it is in d ic a tiv e ). �� � � race may develop above the impermeable layers and in front of the notches. two half-dome niches, more than ten meters high, wide and deep, have developed by multiple processes: weathering induced by the karst waters and intersection of vertical karst cavities by the surface of the retreating rock wall. the recesses with mostly vertical development are also the result of the intersection of karst cavities by the retreating rock wall. the entrance of the buso della fadanana cave is located at the base of a sub vertical channel in the wall: a gully which puts it in relation with the gently sloping surfaces of the ridge located upstream. the cave entrance was nearly completely closed by a talus cone, formed by a body of large collapse blocks (sbcb, in fig. 4), covered by fine clastic deposits, mostly composed by soil and small and medium sized blocks (range between centimetres and decimetres) (lhasc, in fig. 4). the accumulation of the cover sediments (lhasc) is the result of human impact on the surrounding environment during protohistoric and historic times, consisting in the deforestation of the area and the uses of soil for grazing and agriculture (sauro et al., 2007). the cavity has, therefore, according with its topographical position, represented a sedimentary trap. beside buso della fadanana, three others caves have been explored and mapped along the rock wall. all of them fit within the above-sketched hydrogeological model (fig. 3). buso della fadanana is the shortest, developing for about 11 m (but it is possible to see an inaccessible prosecution, inside the sedimentary fillings); grotta di squaranto, also called buso del beco, is the longest, about 145 m in development (salzani & sauro, 1986). 2. the fillings of the cave the deposits inside the buso della fadanana have been partly excavated between 2000 and 2003, in order to analyse their archaeological content (sauro et al., 2007). the digging has evidenced that the upper sedimentary complex has accumulated in a time range between copper and modern age. the over 2 meters’ thick deposit is rich in archaeological materials (ceramics, lithic industry, bones). it presents the structure of a sedimentary cone with layers inclined towards the interior of the cavity (fig. 4). at the base of this upper complex, the loess-like sediments found in the not far grotta di squaranto (salzani & sauro, 1986) are completely missing. this could be probably linked to the occurrence of large collapsed blocks (sbcb) completely closing the cave (see fig. 4). the excavations carried out in the years 2005 and 2006 and supervised by benedetto sala have uncovered different sediments below this upper complex and in the inner part of the cave. this “lower complex” mainly consists of a reddish (munsell color: dry 5yr 6/6, moist 4/6) matrix-supported breccia, made up of a red clay containing clasts as stones, pieces of flowstone, pebbles and fossil bones (lmpsc, in fig. 4). inside the breccia, some thin flowstone levels, and other discontinuities, such as levels of pebbles, slope mostly towards the entrance of the cave, i.e., in opposite direction of the upper complex. some sedimentary structures, as flowstones located under a vertical chimney, in which there is an alternation of calcitic levels and thin levels of red soil sediments, would suggest that at least part of the material present within the breccia could come from karst cavities located above, as the occurrence of vertically-developed cavities in all the karst systems of the area seems to indicate. the reddish clayey matrix (munsell color: dry 5yr 6/6, moist 4/6) clearly represents sediments transported from outside the cave by the erosion of terra rossa type paleosols, perhaps of hapludalfs, hapludults and fragiudalfs type (magaldi & sauro, 1982). the main entry routes of the soil sediments were along the underground karst network, which consists of both vertical and sub-horizontal cavities. the cementation of the sediment is discontinuous: alternating portions of the breccia are extremely hard and others are rather fragile. in some parts, the absence of sedimentary structures suggests the occurrence of solifluction episodes during the deposition. probably, the most singular aspect of the sediments of the lower complex (lmpsc, in fig. 4) is the presence of thousands of small pebbles, mostly limefig. 4 sketch of the section of buso della fadanana, of the related rock wall and of the main sedimentary complexes filling the cavity (the scale both horizontal and vertical is the same and it is indicative). 78 sauro u. & zorzi f. � �� � � stone, dispersed in the reddish matrix, or concentrated to form sub-horizontal levels or lenses. 3. lithology of the small pebbles of the lower complex to better understand the lithology of the pebbles and their possible origins, two different approaches were carried out: (a) observations under the polarizedlight microscope of thin sections from 3 representative reddish breccia bulk samples; (b) x-ray powder diffraction (xrpd) of the red matrix and about 20 pebbles, (divided by color) from the same 3 samples. size and shape of clasts in the reddish breccia are heterogeneous, but there is a fraction of the pebbles that is widespread and often concentrated in small beds (fig. 5). these pebbles have a size range from of 0.5 cm to 1.2 cm, generally rounded to well-rounded ellipsoidal, flattened ellipsoidal, or discoidal in shape. clasts with angular and non-spherical shape are also present and their size ranges from 1 mm to 5 cm or more; most of them are fragments of flowstones (especially the larger clasts), bone fragments, micritic limestones and cherts. the sections and the thin sections of the reddish breccia after resin impregnation (fig. 6) revealed a wide lithological variety of the clasts, mainly from carbonate rocks. all clasts are floating within fine-grained or clay matrix (with a size <10 micron), rich in fe oxides. most of the pebbles are attributable to the geological formations of the lessini area (bosellini et al., 1967) (fig. 7). micritic limestones, grainstones and wackestones with ooids, peloids, crinoids and bivalves are very common and can be related to the jurassic formations. many pebbles are cherts and micritic limestone with the typical paleontological content (calpionellids, radiolarians, globotruncanae) of cretaceous formations. also, grainstone-packstone facies with foraminifera and echinoderms are frequent and they can be related to cenozoic formations. some pebbles are clearly exotic, as they are of metamorphic origin: mica-schist, quartz-schists/gneiss and serpentine-schists (fig. 6). it is also possible to macroscopically recognize some of the lithologies described above: jurassic limestones are grey, cherts are pure white with a black or brown external rim, serpentine-shists are pale green, mica-schists and quartz-schists/gneiss are dark grey or almost black. x ray powder diffraction analyses (xrpd) were carried out on pebbles and matrix of the reddish breccia using a panalytical x’pert pro diffractometer, equipped with co anode, bragg brentano hd mirror, sample spinner and solid state detector (x’celerator). the xrpd analysis of the clay matrix (fig. 8) shows a mineralogical composition typical for a soil: the main phases are smectite (montmorillonite-like), quartz and calcite and the minor phases are muscovite/illite, kaolinite goethite and hematite. most of the pebbles (with colors: grey, pale gray, 79 fig. 5 block of the breccia with a pebbles level. in the center of the breccia there is a 5 cm bone fragment and below there is a 7,5 cm flowstone fragment. problematic karst fillings of late lower pleistocene age in a cave of the monti lessini …. �� � � � � fig. 6 sections: a) section with carbonatic clasts; b) section with carbonatic clasts and metamorphic clasts (green and black clasts). pebbles thin sections under crossed polarizers: c) pebbles of micritic limestone; d) bluish pebbles of serpentinite and lighter pebbles of quartzite. scale bar 1 cm. 80 sauro u. & zorzi f. �� � � �� 81 fig. 7 pebbles thin sections under uncrossed polarizers: a) oolitic grainstone; b) micritic limestone with calpionellids; c) wackestone with globotruncana sp.; d) grainstone with cenozoic foraminifera and echinoderms. scale bar 1 mm. problematic karst fillings of late lower pleistocene age in a cave of the monti lessini …. �� � � white, beige and pale yellow) consist of calcite (fig. 9). some pure white pebbles are composed of quartz and moganite, a common mineralogical paragenesis in cherts (fig. 10). black or dark grey pebbles are composed of quartz and mica (quartzite and mica-schist) (fig. 11). pale green pebbles are totally made of antigorite, a mineral of serpentine group, the major constituent of serpentinites (fig. 12). serpentinites occur in different parts of the alps (mainly in the west alps) and they are associated with the penninic ophyolities. the larger serpentinites outcrops are present in the west alps (aosta valley, lanzo valley, susa valley, voltri massif), 200-300 km away from the buso della fadanana. the nearest sources of serpentinites (100-150 km away) are in the vizze valley (pfitschtal), fundres valley and ultimo valley (de vecchi & baggio, 1982; de vecchi, 1989). pebbles of serpentinites derived from these localities are also found in the fluvioglacial fan of the adige river not far form this area (linear distance of about 20 km) (bertola et al., 2013). 4. significance of exotic pebbles in the karst fillings part of the pebbles is certainly exotic in origin (fig. 5). here we consider exotic both the pebbles made up by lithologies not present in this mountain group, and the pebbles consisting in lithologies not existent in the karst system, although present in some areas of the lessini mountains. it should be emphasized that the red clay matrix and the pebbles must belong to different environments. in fact, the small limestone pebbles are not present in the clay paleosols of the external environments, since these are completely decalcified. it is also evident that the flowstone fragments and the carbonate cement of the breccia are the results of processes that have taken place inside the cave, during and after the emplacement of the sediments described above. the occurrence of exotic pebbles in the karst systems is not rare. in the northern calcareous alps, dispersed on the surface or inside the karst fillings pebbles of siliceous rocks with diameters of a few centimetres can be found. they are called “augenstein” for their dimensions similar to that of an eye (fink, 1975; frisch et al., 2002). similar pebbles also occur in some dolomitic plateaux, such as fanes, sennes and fosses (bini et al., 1990, 1997) and in the slovenian alps (audra et al., 2007). exotic pebbles, mostly of siliceous rocks of a relatively large size range (between millimetres and several decimetres) have been found also on the plateau of the berici, to the sse of the lessini mountains (sauro, 2002, 2005; sauro & ferrarese, 2016). 82 fig. 8 xrpd profile of the clay matrix. legend: sm=smectite, m=muscovite/illite, k=kaolinite, qz=quartz, cc=calcite, g=goethite, h=hematite. fig. 9 xrpd profile of grey pebbles. � fig. 10 xrpd profile of white chert pebbles. sauro u. & zorzi f. �� � � (benedetto sala, personal communication). these paleontological remains could be attributed, according to their excellent state of preservation, to the hunting and transport by birds (andews, 1990; denys c., et al, 2017; laudet f., selva n., 2005). probably, the birds used, as diurnal refuges, one or more cavities above the buso della fadanana, and were transporting remains of preyed animals or regurgitating their wads containing small bones. the deposits originated by these processes have been, later, partly removed and re -deposited in the buso de la fadanana as sediments. 6. discussion and conclusions the upper sedimentary complex (lhasc in fig. 4), rich in archaeological recent holocene finds (late neolithic and copper age), is the result of repeated episodes of frequentation by man, with reworking of sediments in relation to periods of use of the cavity for burial, alternating with periods of use as a dwellings site. the accumulation of these sediments is the result of human impact on the surrounding environment during protohistoric and historic times (sauro et al. 2007). considering the cave as a sedimentary trap, the sedimentation gap of about 0.8 1.0 myr, between the there are three possible general explanations for the origin of the exotic pebbles: i) they have been transported and displaced in the area by morphodynamic agents, such as ancient glaciers and/or watercourses; ii) they belong to a completely eroded geological formation, some elements of which have been trapped in the karstic environment; iii) they are the result of "ecofacts" caused by animals. thus, in the case of the dolomites it is known that the pebbles come from a recent geological formation, of which remains a small strip, trapped within a tectonic structure. instead, in the case of the berici mountains, the presence of exotic pebbles has been explained as linked to the activity of a large river, which could have flattened the “plateau” surface by fluvial abrasion and then entrenched its meanders inside the uplifting relief, before the messinian episode of desiccation of the mediterranean (sauro, 2002, 2005). the case of the pebbles of the buso della fadanana lower complex (lmpsc, fig. 4) is different from those previously described for the reduced dimensional range of the pebbles and for the predominance of lithologies referring to soluble rocks completely missing in the other cases described above. therefore, these pebbles could not go through large-scale transport processes by water, that would have caused their dissolution. according to us, a reasonable explanation is that these pebbles are "ecofacts", i.e: pebbles transported by the birds which use to swallow them to help digestion, then to expel them in the form of boluses or excrements (wings, 2004, 2007; laudet f., selva n., 2005; rosin & kwiecinski, 2011; denys c., et al, 2017). 5. the fauna of the lower complex the fauna of the “lower complex” (lmpsc in fig. 4), still under study, contains erinaceomorpha, several soricomorpha among which beremendia sp., chiroptera, a primate, macaca sylvanus, a large sciurid, a glirid, and several arvicolids among which mimomys savini, clethrionomys sp., pliomys episcopalis, pliomys coronensis, dinaromys sp., microtus arvalidens, microtus nivaloides. the small mammals assemblage is characterized by late biharian species: mimomys savini and microtus arvalidens (sensu fejfar ed heinrich, 1990) and m. nivaloides, and the absence of the small m. pusillus and of allophaiomys. the mimomys savini zone corresponds to the large mammals slivia faunal unit, referred to the reversal magneto-stratigraphic sequence between the jaramillo subchron and the brunhes chron (0,78-0,99 ma) (sala & masini, 2007; masini & sala, 2011) 83 fig. 11 xrpd profile of black pebbles. fig. 12 xrpd profile of pale green pebbles. � problematic karst fillings of late lower pleistocene age in a cave of the monti lessini …. �� � � upper and lower sedimentary complex, entails important remarks. since the buso della fadanana lacks loesslike sediments, recognized in other caves of the area, it is possible that the cavity has been sealed by the cone of large collapsed blocks (sbcb, in fig. 4) until recent holocene. a detailed sedimentological study of the sediments of the lower complex has not been carried out yet, and the excavations have involved only the superficial part of such complex, thus only preliminary hypotheses may be developed about the occurrence of pebbles coming both from local geological formations and from lithologies typical of remote areas (alto adige alps or even the western italian alps; but pebbles made up by similar lithologies are present also in the not far fluvial and till deposits of the adige river and garda moraine amphitheatre). as we have seen, the possible hypotheses about the origin of exotic pebbles are: i) the pebbles could have been transported and displaced in the area by morphodynamic agents, such as ancient glaciers, and/or watercourses; ii) the origin of the pebbles is a geological formation of the area, now completely removed by erosion, constituted by a deposit of pebbles from local and exotic provenience; such pebbles were reworked within the underground karst system, until their emplacement in the described sediments; iii) the presence of pebbles is expression of "ecofacts" of animal origin: birds could have swallowed the pebbles to aid digestion, passively transporting them and subsequently expelling them in boluses as pellets, or in excrements. the first hypothesis seems unlikely, because glacial or fluvioglacial deposits are not known in the area (the nearest local glacial deposits are about 8 km north, and consist only of carbonate rocks; the nearest till deposits of the adige system are located more than 10 km east and in different geomorphological contexts), and, in the case of several episodes of reworking, most of the pebbles, formed by soluble rocks would have been dissolved, and besides, based on natural morphodynamic processes, it is very difficult to explain the narrow dimensional range of the pebbles, as well as the fact that most of them are exotic in the context of this local karstic basin. with reference to the second hypothesis, the materials from which the pebbles originate could have been a geologic formation now completely eroded (cenozoic clastic formation of coastal or continental environment related to the lifting and erosion of the inner alps); the metamorphic pebbles of the cenozoic clastic formation could derive from the erosion of exposed rocks of alto adige alps, because ophiolite (serpentine) and gneiss pebbles from penninic units of tauern window already started to be eroded and redeposited by around 13 my (kuhlemann, 2006 and brugel, 1998); nevertheless this hypothesis implies particular conditions: the cenozoic deposit had to be well sorted and loose because the pebbles in the lower complex breccia are always separated and the pebbles reworking had to be very low, otherwise carbonate pebbles should be missing. therefore, at the moment, the third seems to be the only one hypothesis capable of explaining the presence of pebbles in this context and with the features illustrated. the association of animal bones and pebbles is perhaps due to the presence in this rock wall of different environmental niches, frequented by several species of birds: both predatory birds and other birds (as: vultures, eagles, owls, ravens, etc), which may have transported animal remains as food resources; beside this, some birds, not necessarily of the same species of those related to the presence of bones of mammals, could have swallowed up and then expelled the pebbles in the karst cavities; the pebbles' origin areas could have been the nearby torrent beds of the valleys of the lessini mountains, and, for the pebbles in metamorphic and crystalline rocks, the riverbed and the fluvioglacial fan of the not far adige river (linear distance of about 20 km). the extraordinary abundance of small pebbles could, perhaps, be explained by the preferential choice of cavities open on this rock wall by birds for very long time intervals, of the order of several tens of thousands of years. it should, however, be underlined that the described sediments have unique features, very problematic and not described until now in other alpine karst areas, and that further excavations could, perhaps, help to clarify interesting aspects of the paleoenvironmental evolution of this mountain area. acknowlegements the authors heartily thank benedetto sala for basic information about the faunal association and its chronology (personal communication). thanks also to the anonymous referees for the suggested improvements. references andrews p. 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(1973) il paesaggio degli alti lessini. studio geomorfologico. museo civ. di st. nat. di verona, mem. f. s., 6, pp.161. sauro u. (1974) aspetti dell'evoluzione carsica legata a particolari condizioni litologiche e tettoniche negli alti lessini. boll. soc. geol. it., 93, 945-969. sauro u. (1999) towards a preliminary model of a karst geo-ecosystem: the example of the venetian fore-alps. karst 99, etudes de géographie physisque, suppl. n°. 28, cagep, université de provence, 165-170. sauro u. (2002) the monti berici: a peculiar type of karst in the southern alps. acta carsologica, 31 (3), 99-114. sauro u. (2005) the monti berici: guide of the fieldtrip. geogr. fis. din. quat., suppl. vii, 367-372. sauro u., ferrarese f. (2016) montagne in evoluzione e terremoti: alcuni casi nelle prealpi venete, trentine e gardesane. de rerum natura, numero monografico speciale, museo di storia naturale e archeologia montebelluna, pp.100. sauro u., salzani l., salzani p., fasani l., cozza f. (2007) ritrovamenti dell’età del rame sui lessini. indagini archeologiche in due grotticelle del vajo di squaranto (bosco chiesanuova). bollettino del museo civico di storia naturale di verona, 31, geologia paleontologia preistoria, 99128. wings o. (2004) identification, distribution, and function of gastroliths in dinosaurs and extant birds with emphasis on ostriches (struthio camelus): dissertation zur erlangung des doctorgrade (dr.rer.nat.) mathematisch-naturwissenshaflichen fakultät der rheinischen friedrich-wilhelmsuniversität bon, pp. 187. wings o. (2007) a review of gastrolith function with implication for fossil vertebrates and a revised classification. acta palaeontol. pol., 52(1), 1-16. 85 ms. received: october 1, 2016 final text received: october 3, 2017 problematic karst fillings of late lower pleistocene age in a cave of the monti lessini …. �� � � � 86 microsoft word 00_indice_lm04.docx il quaternario it issn 039-3356 italian journal of quaternary sciences 24 (1), 2011113-119 the argali (ovis ammon antiqua) from the magliana area (rome) roberto rozzi1, maria rita palombo1,2 & maurizio barbieri1 1università degli studi di roma sapienza, roma 2 cnr, istituto di geologia ambientale e geoingegneria. c/o università degli studi di roma sapienza, roma correspondent author: r. rozzi < roberto.rozzi84@gmail.com> abstract: rozzi r., palombo m.r. & barbieri m., the argali (ovis ammon antiqua) from the magliana area (rome). during the middle pleistocene, the fossil subspecies was widespread from georgia to portugal, though it is scantily recorded in local faunal assemblages of southern europe. its occurrence in a few late pleistocene sites needs to be confirmed. in italy, the subspecies is recorded in the late galerian fauna of visogliano (mis 13 10) as well as in the magliana area, where an incomplete skull was found at the beginning of the last century. although the precise location where this specimen was found is unknown, on the basis of the results of the geochemical analysis performed on a small amount of sediment, sampled from the filling of the inner cavities of the horn-cores, and considering the stratigraphy of the area, the hypothesis that the skull comes from the deposits of the pg4 sequence (mis14 partim mis13) cannot be ruled out. this hypothetical remark would confirm the occurrence in italy of the argali in late galerian faunas. the dimensions of ovis ammon antiqua from the magliana area fit well within the range of variability of the larger specimens, likely males, found at la caune de l’arago (france) (mis 14-12), from which the italian specimen differs in having less twisted and more dorsoventrally curved horn-cores. riassunto: rozzi r., palombo m.r. & barbieri m., l’argali (ovis ammon antiqua) della magliana (roma). durante il pleistocene medio, la sottospecie fossile di argali è diffusa dalla georgia al portogallo ma è piuttosto rara nei giacimenti dell’europa meridionale, mentre la sua presenza in alcuni siti del pleistocene superiore deve essere confermata. in italia questa sottospecie è segnalata nella fauna tardo galeriana di visogliano (mis 13 10) e nell’area della magliana, dove, agli inizi del secolo scorso, fu rinvenuto un cranio incompleto. sebbene il luogo esatto del ritrovamento di questo esemplare non sia noto, in base ai risultati delle analisi geochimiche effettuate sul sedimento ancora presente nei cavicchi ossei e tenendo conto dell’assetto geologico stratigrafico dell’area, non si può escludere che il cranio provenga dai depositi della sequenza pg4 (mis14 partim mis13). questo ipotetico riferimento confermerebbe la presenza in italia dell’argali in faune del tardo galeriano. le dimensioni di ovis ammon antiqua della magliana rientrano nel campo di variabilità degli esemplari, presumibilmente maschi, de la caune de l’arago (francia) (mis 14-12), dai quali l’esemplare in studio, tuttavia, si differenzia per una minore torsione e una più accentuata curvatura dorso-ventrale dei cavicchi ossei. key words: argali, ovis ammon antiqua, early middle pleistocene, magliana, italy, parole-chiave: argali, ovis ammon antiqua, pleistocene medio inferiore, magliana, italia. 1. introduction a ovis species, possibly similar to ovis ammon, is first reported in europe in the early pleistocene of bulgaria (ovis sp., slivnitsa, spassov & crégutbonnoure, 1999; crégut-bonnoure, 2005; 2007), while ovis ammon antiqua was undoubtedly present in local faunal assemblages of the middle and, possibly, late pleistocene (crégut-bonnoure, 2005; 2007). in italy, the subspecies is reported in the late galerian fauna of visogliano (mis 13 10, abbazzi et al., 2000; falgueres et al., 2008) as well as in the magliana area (fig. 1), where an incomplete skull was found at the beginning of the last century (portis, 1917). the exact geographical location as well as the precise stratigraphical position of the latter specimen is uncertain. the aim of this paper is twofold: 1) to provide a further morphological description of the specimen retrieved in the magliana area; 2) to hypothesize its stratigraphical position comparing the information included in portis’ paper (portis, 1917) with geological evidence from the area as well as on the basis of new geochemical data. since ovis ammon antiqua is extremely rare in italian local faunal assemblages, a better knowledge of this specimen is useful to further detail the fossil record of the peninsula and to enhance our data on the spreading of this subspecies in southern europe. 2. the puzzling question of the stratigraphical context: geochemical inferences in 1917, portis described an incomplete skull of ovis ammon antiqua (fig. 2) that was retrieved in the magliana area by a building worker and brought to the “regio istituto geologico universitario” of rome by u. rellini. although portis did not know exactly where this specimen was found, after a detailed analysis of the deposits cropping out at “santa passera”, “del truglio”, “delle piche”, “dell’infernaccio”, “della muratella” and “del merlo” hills, he assumed the argali might have been retrieved from deposits overlaying the “pozzolane grigie” (also called “pozzolanelle”, karner et al., 2001). if portis’ hypothesis was correct, the incomplete skull of ovis ammon antiqua would have been younger than r. rozzi, m.r. palombo & m. barbieri 114 these volcanic deposits, deriving from the explosive activity of the alban hills volcanism, which are dated at357 ± 2 ka (karner et al., 2001). this would imply the presence of the argali in the central italy during mis 10 if not at the beginning of the late middle pleistocene. therefore, we have to suppose that sediments where the skull was buried in belong to a sequence not older than the pg5, but whose deposits are scantly or not present in the fosso della magliana area (milli, 1997; milli et al, 2008 and references therein). outcrops of “pozzolane grigie” are actually scanty in the magliana area, where volcanic deposits cropping out more frequently are those of the “santa cecilia formation” (including two volcanic levels dated at 614 ± 15 ka and 605 ± 11 ka, karner & renne, 1998; karner et al., 2001; funiciello & giordano, 2008). moreover occasional outcrops of “tufo pisolitico” have been reported, which have been dated at 561 ± 1 ka (karner & renne, 1998; karner et al., 2001). small clasts of these products, as well as volcanoclastic materials related to sabatini activity, are contained in a few levels of the youngest high-frequency depositional sequences (pg3 and pg4), cropping out in the magliana area (milli, 1997), which are characterized by upper shoreface deposits (pg3) and lacustrine-lagoonal deposits (pg4) (see milli, 1997; milli et al., 2008). in the study area, the sequences pg0, pg1 and pg2, which are older than the beginning of the alban hills volcanic activity, also outcrop in a number of quarry cuts. these sequences are mainly composed of fluvial and beach deposits. therefore, to clarify the stratigraphical position of the magliana specimen, the first step was to analyse a small amount of sediment, sampled from the fillings of the inner cavities of the horn-cores, aiming to check whether its origin was continental or marine. unfortunately no palaeontological content was found to support either of the two hypotheses. accordingly, geochemical analyses were performed in order to verify the presence of volcanic particles in the sediment. a representative portion of each sample was finely powdered using an agate mortar and used for chemical analysis. analyses of metals were carried out using inductively coupled plasma mass spectrometer (icp-ms) after acid total digestion (hf, hno3). analytical blanks were run in the same way as the samples and concentrations were determined using standard solutions prepared in the same matrix. results are expressed in mg/kg (tab. 1), except for fe and al, whose concentrations are expressed in percentage. the accuracy and precision of our results were checked by analysing sediment reference material. tab. 1 concentrations of trace elements expressed in mg/kg (except for al and fe, whose concentrations are expressed in percentage) and carried out using inductively coupled plasma mass spectrometer (icp-ms). concentrazioni di elementi in traccia espresse in mg/kg (tranne che per l’al e il fe le cui concentrazioni sono espresse in %) determinate mediante icp-ms. fig. 1 geological sketch of the thyrrhenian margin, central italy. 1) messinian to holocene sedimentary deposits; 2) pliocene-pleistocene lavas and volcanoclastic deposits; 3) meso-cenozoic sedimentary deposits; 4) main buried faults; 5) strike-slip faults; 6) normal faults; 7) major thrusts. the black square indicates the study area (modified after milli et al., 2008). schema geologico del margine tirrenico, italia centrale. 1) depositi sedimentari dal messiniano all’olocene; 2) lave e depositi vulcanoclastici del pliocene-pleistocene; 3) depositi sedimentari del meso-cenozoico; 4) principali faglie sepolte; 5) faglie trascorrenti; 6) faglie normali; 7) sovrascorrimenti principali. il riquadro in nero indica l’area in studio (modificato da milli et al., 2008). the argali (ovis ammon antiqua) from the magliana area (rome) 115 fig. 2 incomplete skull of ovis ammon antiqua from the magliana area; a) frontal view; b) posterior view; c) lateral view. cranio incompleto di ovis ammon antiqua della magliana; a) norma frontale; b) norma posteriore; c) norma laterale. the content of li and k (with its vicariant elements rb, tl and pb) testifies to the presence of leucite in the analysed sediment. moreover ba, sr and rb are related to pyrossens, while u, cr and w derive from volcanic minerals in general. since the analysis of trace elements confirms the presence of volcanic minerals, such as micas, pyrossen and leucite at various stages of alteration in analcime or clay minerals, the skull of ovis ammon antiqua found at la magliana is at least younger than the beginning of the volcanic activity in the study area, even though we cannot confirm whether these particles are related to the “pozzolane grigie” or not. however, considering the macroscopic similarity between the “pozzolane grigie” and the “tufo pisolitico” (the first pyroclastic flow unit of the alban hills volcanism, de rita et al., 1988; marra & rosa, 1995), locally cropping out in the study area, the hypothesis that elements such as li and k originated from the alteration of these older products cannot be ruled out. the 40ar/39ar age of leucite in “tufo pisolitico” sampled at la magliana is about 561 ± 1 ka (karner & renne, 1998; karner et al., 2001) and the deposition of this volcanic horizon is related to mis 14 (karner & marra, 1998). all in all, we could assume that the argali skull might have been buried during or after the beginning of the “tufo pisolitico” deposition. accordingly, since: the sequence boundary between the pg3 and pg4 is an unconformity surface related to a lowstand phase during mis 14 (milli, 1997); the deposits of pg4 sequence widely outcrops at the top of the hills in the fosso della magliana area, while outcrops of pg5 sequence are scantily or not present and portis considered the skull of ovis ammon antiqua as found at la magliana in levels whose description is consistent with the lacustrine-lagoonal deposits of the tst/hst of the pg4 sequence, we could hypothesize that the study specimen settled in a period covering the ending of mis 14 and the beginning of mis 13. accordingly, the incomplete skull of ovis ammon antiqua might tentatively be ascribed to fontana ranuccio fu as the argali from visogliano, though the latter could be slightly younger (see below). on the other hand, owing to the doubt about the actual location of the finding, and taking into account the age of the oldest volcanic deposits in the area, included in the “santa cecilia formation” (karner & renne, 1998; karner et al., 2001; funiciello & giordano, 2008), we cannot exclude that the argali skull could be older (isernia fu), if recovered from deposits of pg3 sequence. 3. ovis ammon antiqua from magliana in a western european context: comparisons and remarks the argali is mainly recorded in europe during the middle pleistocene, geographically ranging from georgia to portugal (crégut-bonnoure, 2005), though scanty remains close to the species have been reported in the early peistocene local faunal assemblages of sénèze, slivnitsa and apollonia i (kostopoulos, 1996; spassov & crégut-bonnoure, 1999; crégut-bonnoure, 2007). its occurrence in the late pleistocene (koudaro i, sakajia, ortvala, azykh, taglar and mezmaiskaya) needs to be confirmed (crégut-bonnoure, 2005; 2007). the type of the species «ovis antiqua», found at pont-du-château and described by pommerol in 1880 (pommerol, 1880), might be regarded as penecontemporaneous with the argali specimens from la caune de l’arago (crégut-bonnoure, 2007). it comes from levels whose faunal content might be tentatively related to the so-called g3 western mediterranean faunal complex, to which early middle pleistocene lfas referable to french mn 23, spanish mmq3 (in part) ‘‘zones’’, and italian fontana ranuccio fu (late galerian) have been ascribed (see palombo, 2010 and references therein). the richest samples of ovis ammon antiqua come from la caune de l’arago (monchot, 1998; rivals, 2004), where 12,771 remains were retrieved from levels of the middle complex (mis 14-12) (moigne et al., 2006; rivals et al., 2008 and references therein). the specimens found in the two levels don’t show remarkable morphological and biometrical differences. the morphology of the skull and teeth of the specimens found at la caune de l’arago is consistent with the type of the species (rivals, 2004; moigne et al., 2006). the incomplete skull from la magliana (fig. 2) shows some peculiarities in comparison with the remains of ovis ammon antiqua found at la caune de l’arago (fig. 3) and with the type of the species retrieved at pont-du-château (fig. 4). r. rozzi, m.r. palombo & m. barbieri 116 fig. 3 skull of ovis ammon antiqua from la caune de l’arago; a) lateral view; b) posterior view (modified after rivals, 2004). cranio di ovis ammon antiqua da la caune de l’arago; a) norma laterale; b) norma posteriore (modificato da rivals, 2004). in the posterior view, the italian skull differs from the french ones in having squat, less twisted and larger horn-cores relative to the braincase (figs. 2b, 3b, 4b). moreover, the occipital bone of the specimen found at la magliana shows a squared outline, as the specimens from la caune de l’arago, but clearly differing from the type specimen characterized by a rounded and compressed shape of this region. since the dimensions of the remains coming from pont-duchâteau (pommerol, 1880) and la caune de l’arago are rather similar (rivals, 2004; moigne et al., 2006), the differences in the morphology of the horn-cores and of the occipital area cannot be explained in terms of sexual dimorphism, but could be related to intraspecific variability. in the lateral view, a more pronounced dorsoventral curvature and a minor constriction of the horncores characterize the italian skull (figs. 2c, 3a, 4c). since different morphotypes, in particular in the horncores, have been recognized in the extant argali and mouflon (fischer et al.,1983), these differences, as well, could be related to intraspecific variability. the differences in morphology are confirmed by biometrical data, indicating that the occipital region is slightly more vertically elongated in the specimen from la magliana than in the argali from la caune de l’arago. despite such differences, the skull found at la magliana shares a broad similarity in shape and proportions with the specimens used for comparison. in particular, the dimensions of the horn-cores fit well within the range of variability of the larger specimens, likely males, found at la caune de l’arago (monchot, 1998; rivals, 2004) (fig. 5). 4. concluding remarks the results obtained on the one hand show that the morphology and biometry of ovis ammon antiqua skull from la magliana fall within the range of variability of the males found at the french site of la caune de l’arago (corbières massif) in the stratigraphic unit cm1 (about 570 to 530 ka), cm2 (about 530 to 480 ka), and cm3 (about 480 to 400 ka) of the middle complex cm, whose faunas have been correlated with the italian local faunal assemblages (lfas) of isernia (middle galerian) (cm1), and fontana ranuccio (late galerian) (cm2 and cm3) (de lumley et al., 1984; moigne et al., 2006); on the other hand they confirm that the la magliana specimen is younger than the beginning of the volcanic activity in the area, but they do not enable us to unequivocally determine its stratigraphical position. assuming that ovis ammon antiqua was found in the pg4 deposits, this means that the argali was present during the late galerian not only in the north eastern corner of the italian peninsula (visogliano, abbazzi et al., 2000), but also in central italy, albeit in different climate and environmental conditions. the extant argali sheep inhabits mountainous areas in central asia at elevations above 1000 m, though fig. 4 type of the species <<ovis antiqua>> from the pommerol collection; a) frontal view; b) posterior view; c) lateral view (modified after crégut-bonnoure e. & guérin c., 1996). tipo della specie <<ovis antiqua>> dalla collezione di pommerol; a) norma frontale; b) norma posteriore; c) norma laterale (modificato da crégut-bonnoure e. & guérin c., 1996). the argali (ovis ammon antiqua) from the magliana area (rome) 117 fig. 5 scatter diagram comparing the transverse diameter (td) and the antero-posterior diameter (apd) of the horn-cores of both extant and extinct species of the genus ovis. the grey point marked with a star corresponds to ovis ammon antiqua from la magliana. measurements from rivals, 2004, except for the studied specimen. grafico a dispersione che mette in relazione il diametro trasverso (dt) ed il diametro antero-posteriore (dap) dei cavicchi ossei di specie sia fossili che attuali del genere ovis. il punto grigio circondato da una stella corrisponde all’esemplare di ovis ammon antiqua della magliana. misure tratte da rivals, 2004 e originali per l’esemplare in studio. they are not good mountain-dwellers, and prefer slightly sloping areas and open temperate-cold environments dominated by grasses, with very few trees present on the landscape (clark, 1964; shackleton & shank, 1984; geist, 1991). the preferred habitat of the european fossil subspecies would not have been so different, except for elevation, as inferred, for instance, by the environmental context of both late galerian sites of visogliano (northeastern italy) (cattani et al., 1991; abbazzi et al., 2000; arobba et al., 2004; falgueres et al., 2008) and la caune de l’arago (france) (falgueres et al., 2004; moigne et al., 2006; rivals et al., 2008 and references therein). at visogliano, argali remains come from deposits of the middle and upper part (layers 39-11) of shelter a, which were deposited during cold climatic phases, while the species is absent in the lower levels (39-45), deposited during a warm and moist period (arobba et al., 2004). according to falgueres et al., 2008, available data might indicate that the lowest levels possibly deposited during the marine isotope stage mis 13 or that the ‘‘cold’’ levels (levels 11-39) could be correlated with mis 12 and 10, while mis 11 would be largely eroded, contrary to what has already been suggested by various authors (see e.e. abbazzi et al., 2000; arobba et al., 2004). the estimated ages of levels 38-24 range between 445 and 383 ka, suggesting that these layers were deposited shortly after the lowest ones, holding human remains, in spite of the change in climate conditions and faunal content, differentiating layers 45-40 and 39-24. whatever the age of the levels yielding o. ammon antiqua remains, they reasonably deposited during a climate worsening phase. accordingly, the argali was present in the north-eastern italy in quite cold and arid periods, when grasses expanded, forest reduced, and steppe taxa such as ochotona, citellus, microtus gregalis and equus were present, while more temperate species such as dama clactoniana, sus scrofa, macaca and crocidura declined or disappeared (abbazzi et al., 2000). at la caune de l’arago, the stratigraphical unit cm3, correlated with mis 12, shares with visogliano a few similarities in radiometric data and faunal assemblages (falgueres et al., 2004; 2008; moigne et al., 2006). in the faunal assemblage, o. ammon antiqua is present together with some open environment dwellers (e.g. equus, hemitragus, rupicapra, praeovibos, bison priscus) and “cold” species such as rangifer tarandus, but forest dwellers (e.g. lynx, felis silvestris) also occur. consistently, palynological data indicate a number of climatic fluctuations, with alternating phases of cold steppe and temperate forest (renault-miskovsky, 1980). conversely, deciduous forests were present during the deposition of the stratigraphical unit cm2, correlated with mis 13, while colder and drier conditions are documented at the time of the deposition of the stratigraphical unit cm1, correlated with mis 14, when trees were rare and arid steppe spread (renault-miskovsky, 1980). these data and, in particular, the persistence of o. ammon antiqua at la caune de l’arago during quite warm and moist phases, related to mis 13, seem to indicate that the ecological flexibility of the argali allow it to inhabit sparsely wooded and fairly humid environments. on the other hand, a spread of forests in the rome area is documented by the trees association (including broadleaved trees typical of the rainy colchic region) found in the so-called ‘‘tufi litoidi grigi’’, the ‘‘peperino’’ formation of via flaminia (rome) (follieri, 2010), which have been recently dated at around 528 ka by means of 40ar/39ar (karner et al., 2001). the presence of forests in the roman basin at the beginning of mis 13 raises further questions about the times of the presence of the argali in central italy. additional data are needed to clarify times of dispersal towards an extent of dispersion across the italian peninsula of ovis ammon antiqua, as well as the suitable environmental context allowing to its sporadic appearence. acknowledgments the authors are grateful to d. de rita and s. milli for their useful discussion about volcanic products and the geological setting of the magliana area, to mario barbieri for suggestions as to interpreting the geochemical data, and to l. di bella for the palaeontological analysis of the sediment filling the horn-cores. the authors thank the two anonymous reviewers for their comments to the manuscript. references abbazzi l., fanfani f., ferretti m. p., rook l., cattani l., masini f., mallegni f., negrino f., tozzi r. rozzi, m.r. palombo & m. barbieri 118 c. 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(1998) les petits bovidés de la caune de l’arago (tautavel, france): intéret biostratigraphique, archéozoologique et taphonomique quaternaire, 9, pp. 369-377. palombo m.r. (2010) a scenario of human dispersal in the northwestern mediterranean throughout the early to middle pleistocene quaternary international, 223-224, pp. 367-386. pommerol m. (1880) le mouflon quaternaire congrès de l’association française de l’avancement des sciences, 8e session, pp. 600-609. portis a. (1917) il rinvenimento di ovis antiqua pommerol in territorio di roma bollettino della società geologica italiana, 36, pp. 223-232. renault-miskovsky j. (1980) le paléoenvironnement de l’homme de tautavel (caune de l’arago, tautavel, pyrénées orientales): la faune et la flore en roussillon au pléistocène moyen comptesrendus de l’académie des sciences paris, 290, pp. 747-750. rivals f. (2004) les petits bovidés (caprini et rupicaprini) pléistocènes dans le bassin méditerranéen et le caucase. etúde paléontologique, bioestratithe argali (ovis ammon antiqua) from the magliana area (rome) 119 graphique, archéozoologique et paléoécologique british archaeological reports international series, 1327, pp. 1-252. rivals f,, ellen schulz, e., kaiser t.m. (2008) climate-related dietary diversity of the ungulate faunas from the middle pleistocene succession (ois 14-12) at the caune de l’arago (france). paleobiology, 34, pp. 117–127. shackleton d. m., shank c. c. (1984) a review of the social behavior of feral and wild sheep and goats journal of animal science, 58, pp. 500-509. spassov n. & crégut-bonnoure e. (1999) premières données sur les bovidés villafranchiens de bulgarie comptes rendus de l’academie des sciences, series iia, earth and planetary science, 328, pp. 493-498. ms. ricevuto il 25/05/2010 testo definitivo ricevuto il 8/10/2010 ms. received: may 25, 2010 final text received: october 8, 2010 imp.sagnotti contributi del paleomagnetismo alla stratigrafia del pleistocene medio-superiore (brunhes chron) leonardo sagnotti istituto nazionale di geofisica e vulcanologia roma e-mail <sagnotti@ingv.it> abstract: l. sagnotti, the contribute of paleomagnetism to the stratigraphy of the middlelate pleistocene (brunhes chron). this manuscript presents an updated summary on the contribute brought by paleomagnetism to the definition of a high-resolution magnetic stratigraphy for the middle-late pleistocene. the middle-late pleistocene spans a time intervals during which the earth magnetic field held predominantly a stable normal polarity and includes the whole normal polarity brunhes chron. in absence of full reversals of the geomagnetic field, magnetic stratigraphy is based upon (a) the record of geomagnetic paleosecular variations (psv), as documented in archaeological or volcanic material and in lacustrine and marine sedimentary sequences for the last few ka,(b) the variation of geomagnetic paleointensity and (c) the occurrence of geomagnetic excursions . with regards to europe, archeomagnetic psv curves were reconstructed back to 8 ka (i.e., ca. 6000 bc), whereas continuous psv records based on paleomagnetism of sediments extend back to the last 10-12 ka. the variation in intensity of the earth magnetic field has been reconstructed in the detail at a global scale for the last 800 ka. relative paleointensity curves reconstructed in sedimentary sequences provide original correlation and dating tools and are particularly valuable to establish high-resolution age models in sequences that may lack other valuable stratigraphic proxies, such as those deposited in the carbonate-corrosive waters of peri-antarctic margins. finally, the recognition and the dating of geomagnetic excursions, defined as sharp, short-lived and wide geomagnetic variations, during which the earth magnetic field has departed from its usual near-axial configuration but did not give rise to complete reversals, is providing the basis for the establishment of a geomagnetic instability time scale (gits) that extends back to the last 2.2 ma. parole chiave: stratigrafia paleomagnetica, pleistocene medio-superiore. keywords: paleomagnetic stratigraphy, middle-late pleistocene. il quaternario italian journal of quaternary sciences 21(1a), 2008 69-74 introduzione sin dagli anni '60, quando sono state messe a punto le prime versioni della scala temporale delle polarità magnetiche, la classica applicazione delle ricerche di paleomagnetismo negli studi di stratigrafia è stata quella dell'uso delle inversioni di polarità del campo magnetico terrestre (cmt) identificate in successioni stratigrafiche quale elemento geofisico di correlazione a scala globale di sequenze laviche e sedimentarie, terrestri e marine. negli ultimi decenni si sono progressivamente raffinate la conoscenze, e l'inquadramento cronologico, sulle variazioni del cmt a diversa scala temporale. queste conoscenze hanno portato allo sviluppo di potenzialità originali per l'uso del paleomagnetismo a fini stratigrafici anche durante le epoche (chron) a polarità magnetica costante. i risultati ottenuti hanno significativamente ampliato, in particolar modo, le possibili applicazioni stratigrafiche del paleomagnetismo nello studio di successioni rocciose formatesi durante l'attuale epoca di polarità magnetica normale (brunhes chron), che copre gli ultimi 780 ka circa (si rimanda a singer et al., 2005 per una dettagliata discussione della cronologia relativa alla dinamica del cmt a ridosso dell'ultima inversione di polarità del campo). nello specifico, le conoscenze progressivamente acquisite su (a) i cambiamenti locali di direzione del cmt legati alla paleovariazione secolare, sulle variazioni di intensità del cmt (b) e sulla presenza di escursioni geomagnetiche (c) forniscono originali elementi stratigrafici che possono permettere di correlare e datare ad alta risoluzione sequenze stratigrafiche dell'olocene e del pleistocene medio-superiore. nel seguito, verranno sinteticamente esposti gli elementi fondamentali che caratterizzano queste variazioni del cmt ed alcuni esempi di applicazione a fini stratigrafici delle relative registrazioni paleomagnetiche. la paleovariazione secolare l'esecuzione di sistematiche osservazioni dirette sulla direzione del cmt è limitata, nei casi più favorevoli, agli ultimi 4 secoli. queste osservazioni hanno comunque permesso di riconoscere l'esistenza di una variazione secolare del cmt e di definire delle curve locali di variazione della declinazione ed inclinazione del campo a partire dal xvii secolo (per le principali capitali europee). per una breve rassegna della storia delle osservazioni e misure dirette del cmt si rimanda al recente articolo di jonkers (2007) e, per la storia delle misure geomagnetiche in italia in particolare, alle sintesi di cafarella et al., 1992 e lanza et al., 2005a. lo studio del paleomagnetismo delle sequenze sedimentarie e laviche da l'opportunità di estendere nel tempo geologico le misurazioni dirette sulle variazioni del cmt e al contempo fornisce un originale metodo di datazione delle successioni stratigrafiche (e.g. verosub, 1988). in particolare, i dati paleomagnetici relativi a successioni vulcaniche o a successioni sedimentarie ad alto tasso di deposizione (prevalentemente lacustri) ha 70 l. sagnotti portato alla definizione di curve di riferimento per la ricostruzione della paleovariazione secolare (psv master curves) del cmt, valide a scala regionale su aree che si estendono per varie decine di gradi in latitudine e longitudine (e.g. hagstrum & champion, 2002; st-onge et al., 2003; turner & thompson, 1981; 1982). al momento, le psv master curves disponibili per la regione europea si estendono a coprire gli ultimi 10-12 kyr (e.g. snowball et al., 2007) (fig. 1). i dati di psv da successioni sedimentarie hanno il vantaggio di fornire una registrazione “continua” delle variazioni del cmt, ma soffrono al contempo dell'effetto di “filtraggio” del segnale geomagnetico primario, legato alla diluizione temporale dei processi di acquisizione di una magnetizzazione rimanente da parte dei sedimenti durante la deposizione, la compattazione e la diagenesi. questo effetto a sua volta si traduce in una profondità variabile del livello stratigrafico in cui la magnetizzazione naturale risulta effettivamente bloccata e può essere mantenuta per tempi geologici (e.g. bleil & von dobeneck,1999; hyodo, 1984; roberts & winklhofer, 2004; sagnotti et al., 2005; spassov et al., 2003; verosub, 1977). per quanto riguarda le possibili applicazioni a fini stratigrafici nell'area italiana, i dati paleomagnetici sulla paleovariazione secolare del cmt sono stati recentemente applicati quali originale strumento di datazione ad alta risoluzione in sequenze sedimentarie oloceniche sia lacustri (e.g. brandt et al., 1999) che marine (e.g.; iorio et al., 2004; rolph et al., 2004; vigliotti, 2006). d'altra parte, i dati paleomagnetici da sequenze vulcaniche hanno il vantaggio di fornire delle letture “istantanee” ad alta definizione della direzione del cmt all'epoca dell'eruzione, ma soffrono al contempo del limite di essere discontinue a scala temporale. per cui l'uso di tali dati a fini di stratigrafici è vincolato ad una correlazione (sovente non univoca) dei dati paleomagnetici da distinti corpi vulcanici alle psv master curves. le applicazioni dello studio a fini stratigrafici della paleovariazione secolare nei prodotti vulcanici dell'area mediterranea sono numerose e riguardano tutti i principali vulcani attivi italiani (e.g. h o y e , 1981; incoronato et al., 2002; lanza & zanella, 2003; lanza et al., 2005a; principe et al., 2004; rolph et al., 1987; speranza et al., 2004; 2006; tanguy et al., 2003). negli ultimi anni si è sviluppato un vivace dibattito specificatamente focalizzato sui limiti di risoluzione cronologica che possono essere raggiunti con metodi paleomagnetici (si veda arrighi et al., 2005; lanza & zanella, 2006; lanza et al., 2005b; principe et al., 2006; speranza et al., 2005; 2006; tanguy et al., 2005). e' opinione dello scrivente che le incertezze insite nel metodo implicano che le datazioni originali che possono essere ottenute attraverso lo studio paleomagnetico di corpi vulcanici eruttati nel corso degli ultimi migliaia di anni sono solitamente definite con un'approssimazione alla scala secolare, che può restringersi ad alcuni decenni solo nei casi più favorevoli per i periodi caratterizzati da un elevato rateo di variazione direzionale del cmt. nel corso degli ultimi decenni numerosi dati sono stati pubblicati sulla paleovariazione del cmt registrata in materiale archeologico. la mole di dati raccolta ha consentito di mettere a punto varie curve archeomagnetiche di riferimento che si estendono fino a 8 ka (6000 a.c.) circa per le variazioni di direzione ed inclinazione del cmt nell'area europea, con i dati più estesi, continui ed affidabili relativi alla regione francese, alle isole britanniche ed alla bulgaria (e.g. bucur et al., 1994; gallet et al., 2002; kovacheva et al., 1998; zanariri et al., 2007). tali curve vengono poi utilizzate quale riferimento per la datazione di materiale archeologico (principalmente fornaci e terrecotte; si veda jordanova et al., 2004 a titolo di esempio). le variazioni di paleointensità parallelamente alle ricerche sulle variazioni direzionali del cmt si sono progressivamente sviluppate anche le ricerche sulle variazioni di paleointensità del campo. tali ricerche si articolano prevalentemente su due “filoni”: (1) studi volti alla ricostruzione della paleointensità assoluta del campo mediante lo studio paleomagnetico di materiale archeologico (per le ultime migliaia di anni; e.g. aitken et al., 1988; genevey & gallet, 2002), di materiale vulcanico (e.g. hill & shaw, 1999), e di inclusioni ferromagnetiche in singoli cristalli (che arrivano a coprire praticamente l'intera storia della terra; si veda la recente rassegna di tarduno et al., 2007), e (2) studi sulla variazione di paleointensità relatifig. 1 la curva di paleovariazione secolare recentemente pubblicata da snowball et al. (2007) per l'olocene della regione scandinava (fennostack). i dati di declinazione ed inclinazione paleomagnetica sono stati filtrati con una finestra mobile di 150 anni. le curve sottili indicano i limiti superiore ed inferiore di 95% di confidenza associati con le medie mobili. the holocene paleomagnetic secular variation master curve for fennoscandia (fennostack) recently published by snowball et al. (2007). the paleomagnetic declination and inclination data were smoothed with a 150-year running window. the thin lines indicate theupper and lower 95% confidence limits associated with each average value. va registrata in sequenze sedimentarie (e.g. tauxe, 1993; valet, 2003; brachfeld, 2007). quest'ultimo filone è senz'altro quello più utile al fine di datare e correlare successioni stratigrafiche. lo studio di decine di curve di variazione della paleointensità relativa (rpi) del cmt in carote sedimentarie prelevate nei diversi oceani ha portato alla messa a punto di curve sintetiche globali di riferimento che coprono attualmente gli ultimi 800 ka (sint-200 e sint-800 di guyodo & valet, 1996; 1999) e che forniscono una documentazione continua della variazione rpi del campo (fig. 2a). curve regionali a più alta risoluzione sono state successivamente ricostruite per intervalli temporali di più breve durata (quali la napis-75 per l'atlantico settentrionale, laj et al., 2000 e sapis per l'atlantico meridionale; stoner et al., 2002), poi riunite in uno curva sintetica globale (glopis-75; laj et al., 2004) che si estende per gli ultimi 75 ka. la ricostruzione di curve rpi e la correlazione alle curve sintetiche globali di riferimento permettono di definire dei modelli di età originali ad alta risoluzione in sequenze sedimentarie che sono difficilmente databili per altra via, come ad esempio le successioni dai bacini marginali periantartici, ove le acque sono corrosive per i microfossili a gusci carbonatico (e.g. brachfeld et al., 2003; m a c r ì et al. 2005; 2006; sagnotti et al., 2001). le escursioni del cmt le escursioni geomagnetiche sono definite come quei casi in cui il cmt si è notevolmente discostato dalla usuale configurazione di campo prevalentemente dipolare, pressoché allineato all'asse di rotazione. ossia, le escursioni sono state definite come eventi di instabilità geomagnetica in cui il polo geomagnetico virtuale ha avuto una colatitudine > 45°. si tratta di eventi di relativamente breve durata (generalmente < 2 ka) che si concludono senza che si stabilizzi una effettiva inversione di polarità. per l'effettiva distinzione tra escursioni ed inversioni del cmt si rimanda al fondamentale articolo di gubbins (1999). la definizione del numero e la datazione delle escursioni geomagnetiche effettivamente occorse durante il brunhes sono tuttora oggetto di revisione (e.g. ch a n n e l l, 2006; lu n d et al., 2006; m a c r ì et al., 2005; roberts & winklhofer, 2004). un primo tentativo di sintesi è stato proposto nella redazione di una prima scala temporale di 71contributi del paleomagnetismo alla stratigrafia ... instabilità geomagnetica (gits) pubblicata da singer et al. (2002),con ben 14 possibili escursioni nel corso del chron brunhes. nella versione più recente della gits (singer, 2007) il numero di escursioni geomagnetiche nel chron brunhes è ridotto a 12, e la loro occorrenza viene posta in relazione alle variazioni di intensità del cmt per gli ultimi 0.8 ma (fig. 2b). la gits di singer (2007) è estesa agli ultimi 2.2 ma ed include anche le escursioni occorse nella parte alta del chron matuyama. la datazione delle escursioni è solitamente basata su datazioni radiometriche in sequenze vulcaniche o sull'interpolazione e sulla calibrazione astronomica di marker isotopici nelle successioni sedimentarie. in ogni caso, l'identificazione di una escursione geomagnetica in una successione rocciosa ha considerevoli potenzialità ai fini di correlazione e di datazione stratigrafica, in quanto la brevità dell'evento può consentire una datazione dei livelli interessati ad altissima risoluzione. fig. 2 a) la curva sintetica globale di variazione di paleointensità relativa per gli ultimi 800000 anni (sint-800 di goyodo & valet, 1999), b) la “geomagnetic instability time scale” di singer (2007) per il chron di polarità magnetica normale brunhes. in grigio vengono indicate le escursioni che non sono ancora ritenute precisamente datate o che sono meno definite paleomagneticamente. in bianco sono indicate le escursioni datate con maggior precisione e ben documentate in diverse successioni stratigrafiche. a) the global relative paleointensity stack curve for the last 800 ka (sint-800 of guyodo and valet, 1999), b) the geomagnetic instability time scale of singer (2007) for the brunhes chron. grey intervals indicate geomagnetic excursions which are still poorly documented or not yet precisely dated. white intervals indicate the geomagnetic excursions which have been reliably documented in various stratigraphic sequences and are dated with greater accuracy. bibliografia aitken m., a. allsop g. bussell, and m. winter, 1988. determination of the intensity of the earth's magnetic field during archaeological times: reliability of the thellier technique, rev. geophys., 26, 3 -12. arrighi s., j.-c. tanguy v. courtillot and m. legoff 2005. reply to comment by f. speranza et al. on ''recent eruptive history of stromboli (aeolian islands, italy) determined from high-accuracy archeomagnetic dating'', geophys. res. lett., 32(23), l23305, doi:10.1029/2005gl023768. bleil u. and v. dobeneck t., 1999. geomagnetic events and relative paleointensity records clues to highresolution paleomagnetic chronostratigraphies of late quaternary marine sediments? in: use of proxies in paleoceanography: examples from the south atlantic (fischer, g. and wefer, g., eds.), pp. 635-654. springer-verlag, berlin heidelberg. br a c h f e l d s.a., do m a c k e.w., ki s s e l c., la j c., leventer a., ishman s.e., gilbert r., camerlenghi a., eglinton l.b., 2003. holocene history of the larsen ice shelf constrained by geomagnetic paleointensity dating. geology, 31: 749-752. brachfeld s.a., 2007. paleointensity, relative, in sediments in: encyclopedia of geomagnetism and paleomagnetism; 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(it issn 0394-3356, 2011) we report the evolutionary model of the coastal plain of cagliari and the continental relatively late pleistocene holocene, highlighting the strong linkages with similar coastal areas to its tectonic stability of the mediterranean. riassunto: orrù p. et al., evoluzione geomorfologica del sistema piana costiera-piattaforma continentale di cagliari al passaggio pleistocene superiore-olocene, correlazioni con siti stabili mediterranei. (it issn 0394-3356, 2011) viene presentato il modello evolutivo della piana costiera di cagliari e della piattaforma continentale antistante relativamente alla finestra temporale pleistocene superiore – olocene; ponendo in rilievo le forti correlazioni con altre aree costiere a relativa stabilità tettonica del mediterraneo. key words: last interglacial, coastal plain, continental shelf, holocenic sea levels, cagliari gulf parole chiave: ultimo interglaciale, piana costiera, linee di riva oloceniche, golfo di cagliari two lagoons, closed by a system of beach ridges structured in two generations, characterize the cagliari coastal plain similarly to other areas of the mediterranean (ferranti et al., 2006). in particular, strong similarities in terms of geomorphological evolution and of depositional model are recognized, either in other coastal plains of sardinia (porto pino lagoons in the gulf of palmas and mistras-cabras lagoon in the gulf of oristano) than in other mediterranean coastal areas as the plain of fondi, in central italy (antonioli et al., 1988 ) and in the lagoon of santa pola, alicante in southern spain (zazo et al., 2003). the palaeo inner beach ridges of sa illetta and is arenas have been related to the last interglacial (mis 5e) using: i the senegalese fauna as strombus bubonius; ii the u/th analyses on cladocora corals; iii the aminostratigraphy analyses (ulzega & hearty, 1986). the chronostratigraphic age of the paleo-beach of is arenas (last interglacial) has been recently confirmed using together esr analyses (orrù, et al. 2010), and the malacofauna fossils content which includes strombus bubonius (fig.1). the excavation of the foundations diaphragms of the new port terminal of cagliari allowed us to found continuity for the late-quaternary succession through the system of double beach ridges of the western lagoon system (santa gilla lagoon); (fig.2). the continuity of the section allow us to follow a level containing strombus sampled outcropping on the paleo-beach sa illetta, where the burrows in sandy cliffs are surmounted by a layer containing cladocora caespitosa and calcareous algae (ulzega & hearty, 1986). we describe some new sections of the same level, highlighted on a recent excavation performed at 15 m. on the port access channel, the underwater survey has allowed more detailed facies and fig. 1 – fig.1 – strombus bubonius shell from deposits dradged at – 8,5 m (unit 3 of fig.2), few hundred meters far from the la plaia coast line along the entrance channel to the industrial harbour of cagliari strombus bubonius provenienti dal livello dragato a – 8,5 m (unità 3 in fig.2) in corrispondenza del canale di accesso al nuovo porto conteiner, alcune centinaia di metri al largo del cordone litorale di la plaia. 45 47 46 sedimentary structures. the transition to holocene marine deposits is marked by deep incisions founded in both coastal plain and continental shelf, these palaeo-valley began their evolution after the last interglacial highstand while the highest incision was carved during the mis 2 low stand. chrono-stratigraphic study of sediments,14c analyses of peaty, silty and sandy coastal lagoon sediments at the mouth of the lagoon of santa gilla, has enabled us to reconstruct the sea level rise during the holocene (orrù et al., 2004). geophysical surveys (seismic profile orrù et al., 2004; lecca et al., 2005) allowed to follow the palaeo-valleys (mostly buried) carved during low stand along the continental shelf the main heads of the canyons of the board. (fanucci et al., 1976) the lgm lowstand allowed also in other coastal plains the incision of palaeovalley along the continental shelf as in the fondi fossil palaeovalley (antonioli et al. 1988). the holocene sea level rise has been detected studying and dating (14c analyses): seven orders shelf of beach-rock outcropping on the continental shelf (ulzega et al., 1986) the deepest of lay at -45 m (orrù et al., 2004), relict beach bordered the palaeo-lagoon (-39 m), and in the inner band (-35 m) have recently been identified and sampled the submerged back-shore sand dunes overlayed on a large fluvial fan charatterized by to medium and large polygenic gravels. a buried punic age (2500 bp) paleo-sea level at -2 m is preserved in the bottom-area santa gilla lagoon (solinas & orrù., 2006; antonioli et al., 2007). comparing data from the different markers studied: fossiliferous sediments from boreholes, beachrocks, geoarchaeological markers, appear a good correspondence with the predicted sea level curve (lambeck et al., 2010) which indicates a relatively tectonic stability for the coastal area of cagliari during the holocene. references antonioli f., frezzotti m. & valpreda e. 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(2005) sedimenti terrigeno-carbonatici olocenici della piattaforma del golfo di cagliari. il quaternario. 18 (2), 202-221. fig. 2, geologic profile of the lagoon of saint gilla 1) grey-greenish sandy silt (middle pleistocene); 2) sandstones and conglomerates with burrows (upper pleistocene mis 5); 3) littoral carenites containg coastal containing strombus bubonius and cladocora coespitosa (late pleistocene – mis 5e); 4) gray silt quartz in fluvial-deltaic peat (late pleistocene-holocene); 5) littoral sandstone containing cerastoderma and sebka beach rock holocenic transgression (holocene); 6) littoral sandy gravel with posidonia peat (late holocene present); 7) blackish silt and sandy silt of the present lagoon; 8) present sandy beach. profilo geologico della laguna di santa gilla. 1) limi argillosi e argille limose deltizie a ostree (pleistocene medio); 2 ) limi sabbiosi ocra a burrows con lenti calcarenitiche (pleistocene superiore – mis 5); 3) arenarie e conglomerati litorali fossiliferi a a strombus bubonius e cladocora coespitosa (pleistocene superiore – mis 5e); 4) limi quarzosi grigi fluviodeltizi e torbe (pleistocene superiore-olocene); 5) arenarie litorali a cardium e beach-rock di sebka perilagunari (olocene); 6) ghiaie e ghiaie sabbiose di spiaggia con livelli torbosi a posidonia oceanica (olocene-attuale); 7)limi e limi sabbiosi nerastri lagunari (olocene-attuale); 8) sabbie di spiaggia (olocene-attuale)  p. orrù et al. 47 ms. received: testo ricevuto il solinas e. & orrù p. e. (2006) santa gilla laguna: spiagge sommerse e frequentazioni di epoca punica, in aequora, pontos, jam, mare. mare, uomini e merci nel mediterraneo antico, genova 9-10 dicembre, atti del convegno internazionale, giannattasio b.m. 249252. orrù p., antonioli f., lambeck k. & verrubbi v. (2004) holocene sea-level change in the cagliari coastal plain (southern sardinia, italy). quaternaria nova, viii, 193-212. orrù p., antonioli f., hearty p.j. & radtke u. (2010) chronostratigraphic confirmation of mis 5 age of a baymouth bar at is arenas (cagliari, italy). quaternary international. in press ulzega a., leone f. & orrù p. (1986) geomorphology of submerged late quaternary shorelines on the s sardinian continental shelf. journal of coastal research, sl 1, 73-82. ulzega a. & hearty j.p. (1986) geomorphology, stratigraphy and geochronology of late quaternary marine deposits in sardinia. zeitschrift für geomophologie n.f., suppl.bd. 62, 119-129. zazo c., goy j.l., dabrio c.j., bardají t., hillairemarcel c., ghaleb b., gonzález-delgado j.a. & soler v. (2003) pleistocene raised marine terraces of the spanish mediterranean and atlantic coasts: records of coastal uplift, sea-level highstands and climate changes. marine geology, 194, 103-133. january 13, 2011 13 gennaio 2011 geomorphological evolution of cagliari coastal ... imp.ciaranfi.ioniano il piano ioniano del quaternario mediterraneo neri ciaranfi 1*, fabrizio lirer2, patrizia maiorano1, maria marino1 & simona stefanelli1 * autore corrispondente <neri@geo.uniba.it> 1dipartimento di geologia e geofisica, università di bari 2iamc-cnr, napoli abstract: n. ciaranfi, f. lirer, p. maiorano, m. marino & s. stefanelli, the ionian stage in the mediterranean quaternary. the ionian, that corresponds to the middle pleistocene chronostratigraphic time span, is a new stage that extends from matuyamabrunhes reversal, at 0.78 my near to the marine isotope stage 19, up to the middle-late pleiestocene boundary at 0.13 my in correspondence with the base of mis 5. the ionian stratigraphic interval consists in two different parts: the lowest outcrops are well represented on land in two stratigraphic sections in the crotone basin in calabia and in the montalbano ionico area in basilicata. the portion younger than mis 15 is well represented in a core continuosly drilled in the sicily channel ( kc 01b). parole chiave: quaternario, depositi marini, cronostratigrafia . keywords: quaternary, marine deposits, chronostratigraphy. il quaternario italian journal of quaternary sciences 21(1a), 2008 29-34 lo ioniano, la cui denominazione è stata proposta nel corso del workshop organizzato tra il 29 settembre ed il 4 ottobre 1994 dal gruppo di studio sul quaternario della commissione italiana di stratigrafia, rappresenta l'intervallo cronostratigrafico corrispondente al pleistocene medio (cita & castradori, 1994; 1995; van couvering, 1995; cita et al., 2006). in accordo con l'uso informale di questo termine, che è ormai stato ampiamente utilizzato nella letteratura sia italiana che internazionale, il piano ioniano si estende dal limite matuyama-brunhes, pressoché coincidente con il mis (marine isotope stage) 19, fino alla base del mis 5, che corrisponde all'inizio del pleistocene superiore (vai, 1996; cita et al., 2005; cita et al., 2006): copre quindi un intervallo di tempo compreso fra circa 0.78 ma e circa 0.13 ma. il termine ioniano, seppur proposto da pochi anni, è riportato in alcune delle più recenti scale cronostratigrafiche (gibbard & kolfschoten, 2004; gibbard et al., 2004; 2005; 2007). il suo uso è stato ribadito al recente congresso internazionale dell'inqua (pillans, 2007), sebbene non sia stata ancora formalmente individuata la sezione stratigrafica nella quale definire il gssp di questo piano. a tale scopo, sia in occasione del congresso inqua 2007 che del workshop della commissione italiana di stratigrafia (fist 2007), sono state proposte la sezione di valle di manche, nel bacino crotonese, e la sezione di montalbano ionico, nell'avanfossa sudappenninica in basilicata. l'intervallo stratigrafico compreso fra 0.78 ma e 0.13 ma è rappresentato nelle due successioni in terra sopra citate e in diversi pozzi (figs. 1 e 2) perforati durante le crociere ocean drilling program nel mediterraneo (odp leg 107, 160, 161); in particolare solo la parte inferiore dello ioniano è esposta nelle sezioni affioranti di valle di manche e di montalbano fig. 1. ubicazione delle sezioni in terra e di alcuni dei pozzi perforati nel mediterraneo che meglio rappresentano il piano ioniano. modificata da cita et al. (2006). location of the land sections and of some well drilled in the mediterranean in which the ionian stage is better exposed. modified by cita et al. 82006). ionico, le quali includono rispettivamente i mis dal 22 al 18 (capraro et al., 2005) e i mis dal 22 al 15 (ciaranfi et al, 2001) (fig. 3). la parte più recente dello ioniano, a causa della cessazione del ruolo di avanfossa subsidente nel corso del pleistocene medio (ciaranfi, 2004) 30 n. ciaranfi et al. fig. 2. successioni stratigrafiche maggiormente significative per gli intervalli calabriano e ioniano nell'area mediterranea (da cita et al., 2006, modificata). the detailed studied stratigraphic successions of the mediterranean area in which calabrian and ionian stages are well rprsented. from cita et al. (2006), modified. dell' area bradanico-ionica e dell' emersione subita nel corso dello stesso pleistocene medio/ pleistocene superiore, non è osservabile in affioramento, salvo alcune sezioni stratigrafiche di spessore assai modesto che affiorano nell'entroterra del golfo di taranto e che rappresentano la parte sommitale di questo piano, al passaggio con il sovrastante tarentiano (cita & castradori, 1995). l'intervallo stratigrafico compreso fra gli stadi isotopici mis 15 e mis 5e è invece ben rappresentato nei site 653, 963, e 964 e, in particolare, nella carota kc01b (figs. 2 e 3) che è stata recentemente ricalibrata su base astronomica (lourens, 2004). un'accurata stratigrafia integrata basata su biostratigrafia del plancton calcareo (foraminiferi e nannofossili), stratigrafia isotopica dell'ossigeno e stratigrafia a sapropel, è disponibile per le successioni in pozzo (r i o et al ., 1990; castradori, 1993; sprovieri et al., 1998; di stefano, 1998; d e ka e n e l et al., 1999; kr o o n et al., 1998; rossignol-strick & paterne, 1999; lourens, 2004; maiorano & marino, 2004; raffi et al., 2006). inoltre, anche le successioni in terra risultano ben inquadrate in un preciso schema biocronostratigrafico, come documentato da recenti lavori sia per la sezione di valle di manche (rio et al., 1996; massari et al, 2002; capraro 31il piano ioniano del quaternario mediterraneo et al., 2005), che per la sezione di montalbano ionico (ciaranfi et al., 2001; ciaranfi & d'alessandro, 2004; maiorano et al, 2004; stefanelli et al., 2005). la sezione di valle di manche (fig. 3) è parte di una successione composita caratterizzata da sedimenti che mostrano una complessiva tendenza alla superficializzazione, da mudstones di scarpata a depositi da marini marginali a continentali (massari et al., 2002; capraroet al, 2005); la sezione, in particolare, contiene un livello tefra (pitagora ash) in prossimità del quale è stato riconosciuto il limite paleomagnetico matuyama/ brunhes (rio et al., 1996; massari et al., 2002). la sezione di montalbano ionico è rappresentata da sedimenti che mostrano una tendenza regressiva da piattaforma esterna fino a spiaggia sommersa (ciaranfi et al., 1997; ciaranfi et al., 2001) come evidenziato anche dalle associazioni di organismi macrobentonici (d'alessandro et al., 2003) e di foraminiferi bentonici (stefanelli, 2003), ed include diversi livelli vulcanoclastici (fig. 3). l'insieme dei dati stratigrafici disponibili, ossia il record del δ18o, la biostratigrafia a nannofossili calcarei e i livelli sapropelitici correlati con la stratigrafia a sapropel di lourens (2004) hanno consentito di ottenere una calibrazione astronomica della successione fig. 3. caratteri stratigrafici delle sezioni di valle di manche e di montalbano ionico e correlazione con la carota kc01b per l'intervallo ioniano. valle di manche da capraro et al. (2005); montalbano ionico da ciaranfi et al. (2001); carota kc01b da lourens (2004) main stratigraphic features of the valle di manche and montalbano jonico sections, and their correlation with the ionian succession in the kc01b core. valle di manche from capraro et al. (2005); montalbano ionico from ciaranfi et al. (2001); kc01b core from lourens (2004). 32 f ig . 4 . c a li b ra z io n e a s tr o n o m ic a d e ll a s e z io n e d i m o n ta lb a n o i o n ic o e c o rr e la z io n e c o n l a c u rv a d i ri fe ri m e n to d e l δ1 8 o d e l m e d it e rr a n e o d i l o u r e n s e t a l. ( 2 0 0 4 ): v 1 -v 9 = l iv e ll i v u lc a n o c la s ti c i; i -5 6 /i -1 1 8 = c ic li d i in s o la z io n e s e c o n d o l o u r e n s e t a l. ( 2 0 0 4 ); b io s tr a ti g ra fi a a n a n n o fo s s il i c a lc a re i d a m a io r a n o e t a l. ( 2 0 0 4 ); f o = f ir s t o c c u rr e n c e ; f c o = f ir s t c o m m o n o c c u rr e n c e ; l c o = l a s t c o m m o n o c c u rr e n c e ; td = t e m p o ra n e a a s s e n z a d i g e p h y ro c a p s a o m e g a ; “ in fl u x g . c ra s s a fo rm is ” . a s tr o n o m ic a l c a li b ra ti o n o f m a o n ta lb a n o j o n ic o s e c ti o n a n d c o rr e la ti o n w it h t h e δ1 8 ° m e d it e rr a n e a n r e fe re n c e c u rv e o f l o u r e n s e t a l. (2 0 0 4 ): v 1 -v 9 = v o lc a n ic la s ti c l a y e rs ; i5 6 /i -1 1 8 = in s o la ti o n c y c le s a c c o rd in g t o l o u r e n s e t a l. ( 2 0 0 4 ); c a lc a re o u s n a n n o fo s s il b io s tr a ti g ra p h y f ro m m a io ra n o e t a l. ( 2 0 0 4 ); f o = f ir s t o c c u rr e n c e ; f c o = f ir s t c o m m o n o c c u rr e n c e ; l c o = l a s t c o m m o n o c c u rr e n c e ; td = t e m p o ra rr y d is a p p e a ra n c e o g g e p h y ro c a p s a o m e g a ; “ in fl u x g . c ra s s a fo rm is ” . n. ciaranfi et al. 33il piano ioniano del quaternario mediterraneo (fig. 4) ed una cronologia dei livelli tefra (ciaranfi et al., submitted). in particolare alcuni dei livelli vulcanoclastici sono stati correlati, sulla base della loro età, con livelli di tefra già riconosciuti nel bacino del mediterraneo e con la loro cronologia come proposta da lourens (2004): v8 (592,29 ka) con il tefra vdd-3 (596±6 ka, karner et al., 1999) e i 29 (595,3 ka, lourens, 2004), v6 e v5 (rispettivamente 618,06 ka e 627,34 ka) sono invece entrambi correlabili con i 30 (622,8 ka, lourens, 2004). inoltre, il livello vulcanoclastico v4, riconosciuto in corrispondenza dello stadio isotopico 19 e probabilmente correlabile con il pitagora ash del bacino crotonese (fig. 3), è stato datato a 785.38 ka, età prossima a quella del limite m/b (fig. 4). bibliografia capraro l., asioli a., backman j., bertoldi r., channell j.e.t., massari f. & rio d. 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(2004) calcareous nannofossil events in the lower-middle pleistocene transition at the montalbano jonico section and odp site 964: ms. ricevuto il 2 aprile 2008 testo definitivo ricevuto il 17 aprile 2008 ms. received: april 2, 2008 final text received: april 17, 2008 34 n. ciaranfi et al. calibration with isotope and sapropel stratigraphy. riv. it. paleont. e strat., 110, 547-557. massari f., rio d., sgavetti m., prosser g., d'alessandro a., asioli a., capraro l., fornaciari e. & tateo f. (2002) interplay between tectonics and glacio-eustasy,pleistocene of the crotone basin, calabria (southern italy). boll. am. geol. soc., 114, 1183-1209. pillans b. (2007) defining the quaternary. xvii inqua congress 2007, cairns convention centre, cairns, australia 28 july 3 august. raffi i., backman j., fornaciari e., pälike h., rio d., lourens l. & hilgen f. (2006) a review of calcareous nannofossil astrobiochronology encompassing the past 25 million years. quat. sci. rev., doi:10.1016. rio d., raffi i. & villa g. (1990) pliocene-pleistocene calcareous nannofossil distribution patterns in the western mediterranean. in kastens ka, mascle j., et al., proceedings of the odp sci. res., 107, 513-532. rio d., channell j.e.t., massari f., poli m.s., sgavetti m., d'alessandro a. & prosser g. (1996) reading pleistocene euastasy in a tectonically active siliciclastic shelf setting (crotone peninsula, southern italy). geology, 24, 743-746. rossignol-strick m. & paterne m. (1999) a synthetic pollen record of the eastern mediterranean sapropels of the last 1 ma: implications for the timescale and formation of sapropels. mar. geol., 153, 221-237. sprovieri r., di stefano e., howell m., sakamoto t., di stefano a. & marino m. (1998) integrated calcareous plankton biostratigraphy and cyclostratigraphy at site 964.proc. odp sci. res., 160, 155165. stefanelli s., 2003. benthic foraminiferal assemblages as tools for paleoenvironmental reconstruction of the early-middle pleistocene montalbano jonico composite section. boll. soc. paleont., 42(3), 281299. stefanelli s., capotondi l. & ciaranfi n. (2005) foraminiferal record and environmental changes during the deposition of the early-middle pleistocene sapropels in southern italy. palaeogeogr., palaeoclim., palaeoecol., 216, 27-52. vai g.b. (1996) revisione critico-storica dei piani marini del quaternario. serv. geol. d'it., miscellanea, vi, 1-179. van couvering j.a. ( 1995) setting pleistocene marine stages. geotimes, 40, 10-11. microsoft word 00_indice_06lm.docx   il quaternario it issn 039-3356 italian journal of quaternary sciences 24 (2), 2011 153-169 lower pleistocene deposits in east part of the favignana island, sicily, italy andrzej ślączka1, fabrizio nigro2, pietro renda3 & rocco favara2 1 inst. of geological sciences, jagiellonian university, kraków, poland 2 istituto nazionale di geofisica e vulcanologia, sez. di palermo, palermo 3 dip. geologia e geodesia, università di palermo, palermo corresponding author: p. renda <pietro.renda@unipa.it> abstract: ślączka a. et al., lower pleistocene deposits in east part of the favignana island, sicily, italy. in the favignana island (egadi archipelago, sicily, central mediterranean) pleistocene shallow water marine deposits are widely well exposed to form a prograding beach/near foreshore complex system. a group of facies associations have been recognised, suggesting different depositional environments and processes, related both to currents dynamics, palaeoclimatic conditions, sea-level changes and syn-sedimentary tectonics. the sedimentological pattern of the facies allow to reconstruct the depositional history of the island, characterised by the interplay of long/oblique shore currents dynamics and storm events during the lower pleistocene, developed on a mobile mesozoic bedrock just affected by strike-slip tectonics riassunto: ślączka a. et al., i depositi del pleistocene inferiore nel settore orientale dell’isola di favignana, sicilia, italia. nell’isola di favignana (arcipelago delle egadi, sicilia occidentale), affiorano estesamente calcareniti infrapleistoceniche, ben esposte soprattutto lungo le pareti delle numerose cave a pozzo, oggi dismesse, presenti nel settore orientale dell’isola. le calcareniti sono caratterizzate da un complesso sistema di associazioni di facies, che nel loro complesso indicano ambienti deposizionali di spiaggia/mare basso, e ricoprono in discordanza successioni carbonatiche mesozoiche deformate, che costituiscono le unità tettoniche esterne della catena siciliana, messe in posto nel miocene superiore depositi, di età pleistocenica inferiore, affiorano estesamente sia nel settore orientale che in quello occidentale dell’isola e sono separati da una dorsale carbonatica mesozoica, affiorante nel settore centrale. le migliori esposizioni di questi depositi si rinvengono nel settore orientale, dove sono state riconosciute cinque associazioni di facies. l’analisi sedimentologica ha permesso di ricostruire gli ambienti ed i processi sedimentari, che sembrano essere il risultato dell’interazione sia di dinamiche di correnti, di condizioni paleoclimatiche e di oscillazioni eustatiche, oltre che di deformazioni tettoniche sin-sedimentarie. le geometrie stratali, le strutture sedimentarie e le ichnofacies hanno permesso di distinguere nel settore orientale di favignana associazioni di facies caratteristiche di ambienti di spiaggia sommersa nei quali si è sviluppato un sistema di barre disposte obliquamente rispetto alla paleolinea di riva. la diffusa presenza di strutture erosive e di depositi canalizzati suggerisce che la deposizione sia avvenuta per lo più al di sopra del livello di base delle onde e che a luoghi sia anche stata condizionata da eventi di tempesta. l’evoluzione verticale delle facies mostra inoltre che la sedimentazione è stata anche controllata sia da oscillazioni del livello del mare che da mobilità del substrato, soggetto a deformazioni tettoniche, come evidenziato da numerose faglie di crescita presenti a diverse scale entro i depositi calcarenitici. keywords: depositional processes, sinsedimentary tectonics, pleistocene, egadi-sicily. parole chiave: processi deposizionali, tettonica sin sedimentaria, pleistocene, isole egadi, sicilia. 1. introduction the lower pleistocene (calabrian; malatesta, 1955) sediments exposed along some cliffs and in the quarries in the eastern sector of the favignana island (fig. 1), between favignana town and punta marsala, are a good example of ancient shoreface deposits (abate et al., 1999): the main purpose of this study is to describe them for try to define their depositional environments. the sediments of the favignana basin show general similarity to the upper pliocene-lower pleistocene calcarenite di gravina formation outcropping in apulia region, whose paleographical and sedimentological features were discussed in several papers (e.g. d’alessandro & bromley, 1986; d’alessandro et al.,1993; d’alessandro & massari, 1997; iannone & pieri, 1979; massari & chiocci, 2006; mateu-vicens et al., 2008; pomar & tropeano, 2001). the deposition of favignana pleistocene sediments was strongly influenced by the size and shape of the island. the paleofavignana island probably was smaller than presently. the clastic sediments forming calcarentes mainly derive from redeposition of ancient shore material and from very common skeletal remains of bentic organisms (fig. 2); a negligible part of clastics derive from the mesozoic calcareous rocks. the main controlling factor of the coastal sedimentation was the interplay of fair weather and storm periods, as already point out for similar lower pleistocene deposits, (massari & parea, 1988, mateu-vicens et al., 2008), also by prossible tsunamis (tinti, 1993). relative changes of sea level caused by local tectonic movements ślączka a. et al. 154 during lower pleistocene (abate et al., 1995) and by regional sea level fluctuations (tropeano & sabato, 2000) have an important role for the favignana area. 2. geological setting the favignana island belongs to the egadi archipelago (fig. 1) that represents an emerged part of the egadi thrust belt (abate et al., 1995-1997) of sicilianmaghrebian system (sulli, 2000; nigro & renda, 2001). favignana is mainly build-up of mesozoic-lower tertiary carbonate deposits, unconformably capped by younger sediments which are represented by biocalcarenites and biorudites of early-middle miocene and marly shales of late miocene (catalano et al., 1996; abate et al., 1997). mesozoiclower tertiary carbonate deposits are unconformably covered by middle-upper pliocene bluish marls and shale followed by lower pleistocene calcareous deposits and by tyrrhenian calcarenites and biorudites. the lower pleistocene depo sits are widespread along the eastern slope of the emerged paleo-favignana island in a pullapart basin, probably generated by transtensional faults activity. three faults systems, recognised in the favignana island, displace both the mesozoic-tertiary and pleistocene deposits (fig. 3). the first system, represented by n-s strike-slip faults, bounds the ridge of favignana and somewhere it reactives/displaces the miocene thrusts (abate et al., 1995). the other faults systems nesw and nnw-sse oriented at low-angle pitches. minor positive flower structures 1-to-10 meters in scale have also been observed (incandela, 1995; 1996; abate et al., 1995). in the eastern sector of the island, joints and minor strike-slip faults deform the deposits of pleistocene age, as well as the more younger breccias and paleosoils with displacements ranging from 0.1 to 1 m. this faulting activity determined smallscale block tilting, as recognised at cala monaci. in the middle-southern sector of the island a n-s oriented morphostructure (so-called promontorio scindo passo), is located and bounded by two strike-slip faults. the outcropping pleistocene deposits are displaced by minor right-hand transtensional and normal faults oriented nnw-sse. this grid of minor faults determined pull-apart like geometries in the north-western sector of the island (punta sottile) outcrop conglomerates and sandstones of pleistocene age, that are displaced by strike-slip and normal faults oriented from nw-se to w-e. the sandstones also fill the faults-related joints, suggesting soft-sediment deformation processes. also, between the localities of cala del pozzo and punta di ferro, outcrop gravels and sandstones of pleistocene age are deformad by nw-se and w-e oriented strike-slip faults (incandela, 1996; abate et al., 1995; 1997). in the northern sector of the island (punta faraglione), right-hand strike-slip faults oriented from nw-se to w-e, formed a set of meters-in-scale graben-like structures, filled by marine deposits of pleistocene age. this deposits are deformed by left-hand strike-slip faults ne-sw striking. finally, the pleistocene sandstones outcropping in the eastern sector of the island are folded to form a gentle anticline, interpreted as a drag-fold by incandela (1996) and abate et al., (1995). fig. 1. a) schematic structural map of the western sicily; b) schematic geological map of the favignana; c) pleistocene facies distribution in the eastern favignana island. a) carta strutturale schematica della sicilia occidentale; b) carta geologica schematica dell’isola di favignana; c) distribuzione delle facies pleistoceniche nel settore orientale dell'isola di favignana. lower pleistocene deposits in east part of the favignana ... 155 3. description of lithofacies several facies associations can be locally described on the basis of coexistence of lithological features, sedimentological structures and trace fossil assemblages. relationship between the facies associations are in some cases of hard interpretation because of lacking of several diagnostic elements: all the stratigraphic sections are incomplete, the basal lower pleistocene deposits are frequently unexposed and the erosion and/or faulting cut the topmost part of the successions. 3.1 facies association a this association, whose visible thickness is about 10 meters, is exposed in the western margin of the favignana basin between cala fumere and tonnara florio (north of the town of favignana, fig. 1c). it is generally represented by coarsening up sequence of calcarenites and conglomerates (fig. 4). the bottom of the sequence is masked by strike-slip fault. in the lower part, fine-to-coarse grained calcarenites, up to several dozen cm thick, display a variety of laminations, from parallel to cross-bedded in lunate megaripples and to wave ripple lamination1. in the upper part of the sequence, whose thickness can reach 1.5 meters, predominate conglomerates (fig. 4c) composed of rounded and subrounded pebbles derived from the erosion of the mesozoic bedrock, as well as from other lower pleistocene deposits. the size of sporadic boulders can reach dozen cm. scattered fragments of bivalve shells, rhodolithes and serpulite limestones also occur. the matrix consists in abraded bioclastics. conglomerates show crude parallel-bedding (pettijhon, potter & siever, 1987) and low angle cross bedding seaward directed; somewhere they are massive, without distinct internal structures. parallel-bedded conglomerates include small lenses of cross-laminated calcarenites. inclination of lamination is generally parallel or oblique to the coastline. conglomerate bodies present an erosional basal surface signed by broad shallow channels. trace fossils, random distributed in the sediments, must be referred to three ichnogenera, thalassinoides, planolithes and thenidium; somewhere vertical traces of skolithos-like also occur (fig. 4c). few beds of calcarenites are pervasive bioturbated (fig. 4d), locally limestone with borings can be observed in blocks up to tens cm in diameter. 1 locally there are bi-directional set of lenses (fig. 4a) and in places wave ripples follow upward megaripples. on some inclined laminae there are lags of gravels and shells (fig. 4b). also, between laminated bodies there are lags of flat limestone pebbles and thin (up to dozen cm) layers and/or lenses of conglomerates, formed by rounded pebbles of mesozoic limestones, bioclasts and fragments of molluscs and echinoids shells (fig. 4b). some layers (up to 50 cm thick) display distinct gradation from matrix supported carbonate pebbles and fragment of shells in lower part to coarse and medium grained calcarenites topwards. fig. 2. a) bioclastic sandstone with red algal clast, foraminifera and sporadic bryozoan. punta burrone. length of bar is 2 mm; b) bioclastic sandstone with foraminifera, bivalve shell fragments, bryozoan, red algae. punta fanfalo. length of bar is 2mm; c) fine grained bioclastic sandstone with numerous foraminifera. area of frascia. length of bar is 1 mm; d) bioclastic sandstone with red algae, bivalve shell fragments, bryozoan and foraminifera. madonna-cortigliolo. length of bar is 2 mm. a) arenaria bioclastica con clasti di alghe rosse, foraminiferi e sporadici briozoi. punta burrone. la lunghezza della barra è 2 mm; b) arenaria bioclastica con foraminiferi, frammenti di gusci di bivalvi, briozoi ed alghe rosse. punta fanfalo. la lunghezza della barra è 2 mm; c) arenaria bioclastica fine con numerosi foraminiferi. località frascia. la lunghezza della barra è 1 mm; d) arenaria bioclastica con alghe rosse, frammenti di gusci di bivalvi, briozoi e foraminiferi. madonna-cortigliolo. la lunghezza della barra è 2 mm. fig. 3 schematic structural map of the favignana island showing the main faults that deform the pleistocene deposits carta strutturale schematica dell'isola di favignana che mostra le principali faglie che deformano i depositi del pleistocene. ślączka a. et al. 156 fig. 4 facies association a (beach/nearshore zone), area of cala fumere, north from the town of favignana. a) lower part of the sequences started with bi-directional bundled cross-bedded lenses covered by thin layer of conglomerate built up of fragments of moluscs and echinoidea shells and unidirectional cross bedded calcarenites. length of penknife is 11 cm; b) cross-bedded calcarenites with lags of limestone pebbles along inclined laminae and covered by parallel laminated calcarenites with pebbly lags. length of penknife is 11 cm; c) layer of conglomerate showing crude gradation with well rounded limestone pebbles. sporadic vertical burrows (b). length of penknife is 11 cm; d) pervasive bioturbated calcarenites. in lower part of the picture burrowed limestone boulder (l) with borings. length of penknife is 11 cm associazione di facies a (zona beach/nearshore), area di cala fumere, a nord della città di favignana. a) la base della sequenza inizia con lenti a stratificazione incrociata a festoni bidirezionali ricoperte da un sottile strato conglomeratico costituito da frammenti di molluschi ed echinidi e calcareniti a stratificazione incrociata unidirezionale. la lunghezza del temperino è 11 cm; b) calcarenite a stratificazione incrociata con isolati ciottoli carbonatici disposti lungo lamine inclinate e ricoperti da calcareniti a laminazione piano-parallela con clasti isolati. la lunghezza del temperino è 11 cm; c) orizzonte conglomeratico scarsamente gradato, con ciottoli di calcare ben arrotondati. sporadici burrows verticali (b). la lunghezza del temperino è 11 cm; d) calcareniti ampiamente bioturbate. nella parte inferiore della foto si osserva un ciottolo carbonatico (l) perforato. la lunghezza del temperino è 11 cm. predominance of coarse-grained sediments and sedimentary structures suggest that facies association a (fig. 1c) represents high wave energy beach/upper foreshore zone (pomar & tropeano, 2001; clifton, 2006; bridge & demicco, 2008). in this zone storm sediments, represented by pebbly lags, passing upwards to finer laminated deposits, graded beds, lunate megaripples and pebbly layers, are interrupted by fair weather conditions when developed wave ripple lamination and burrowed interval (clifton, 1976; johnson & baldwin, 1986). seaward deeping cross-bedding prevailed. occasionally longshore southward currents appeared. observed intricately interwoven cross-lamination are characteristic of wave origin and connected probably with fair-weather period. very thick conglomerates near the top of sequence can mark exceptional strong storms events. due to storms cyclicity, deposits of previous periods were partly eroded and are only partially preserved. increase of conglomerates in the upper part of the sequence is linked to the increase of storm magnitude in lapse of time. periodically pervasive bioturbated horizons took place. 3.2 facies association b facies association b, whose thickness not exceeds 10 meters, is located between punta lunga and lido burrone, southwards of favignana town (fig. 1c) and reaches favignana harbour towards the north. it is characterized by the occurrence of calcirudites with several algae remains and rhodolithes and occurrence of horizons with thalassinoides. relationships to the previous facies association is not clear in the souther part (cala monaci) due to the lack of exposures. however data from the harbour of favignana imply that facies association b is generally situated farther to east than the previous one. relationship with older substratum is unknown. the outcrop of this association starts near punta lunga with thick bedded/massive conglomerates (fig. 5a) built-up mainly by rhodolithes, up to dozen cm in size, fragments of serpulite and, somewhere, by fragments of bivalve shells. erosive surfaces bound lower pleistocene deposits in east part of the favignana ... 157 base of some conglomerates, displaying broad but general shallow (several tens of cm) channels. crude planar cross-bedding is visible in topmost part of the section. in the western sector the conglomerates can reach 3 meters thick. there are lenses, up to 1.5 meters thick, composed by calcarenites rich in mollusc shells that display in their lower part crude lamination, that becomes more chaotic upwards (fig. 5b). the upper part of the sequence consists of thick-bedded conglomerates, displaying erosive base with planar westward cross-bedding, locally underlined by lag of single, ellipsoidal pebbles. decreasing of size of clastics is visible (fig. 5c) landwards. in some localities, homogenous medium-grained calcarenites, up to several tens cm thick, enriched in pelitic material, show a medium bedding. the sequence generally stops with coarsening-up strata, homogenous in their lower part, showing lowangled lamination near the top, covered by laminated bioturbated calcirudites (fig. 5d) with eastward dipping and muddy drapes. somewhere channelized conglomeratic beds with pebbles, rhodolihts and shell fragments, in which the size of clastics and thickness of layers is decreasing eastward, can be observed. conglomerates show a cover of oblique cross-bedded layers, generally dipping toward ese, pervasively bioturbated and topped or by a bundled part (fig. 5e) and by horizontal laminated or wave laminated calcarenites. calcirudites with rhodoliths crop out eastward, almost up to lido burone locally. broad and deeply incised erosional channels, nw-se and n-s directed, filled up by stack of oblique and locally sinuosinoidal cross laminated material with very coarse grained material concentrated in the middle part of inclined layer (fig. 5f), can be observed. thin, pelitic horizons separate individual laminated set. the calcirudites in punta lunga are locally cut by scolithostype traces (fig. 5d) and on the upper surface there is characteristic network of thalassinoides (fig. 5g) and sporadic ophiomorpha (fig. 5h). this can represent cruziana and skolithos ichnofacies (bromley, 1996; seilacher, 1967) or thalassinoides skolitus suite of d’alessandro et al. (1993). facies association b, mainly deposited by storm waves of high magnitudes, could represent a portion of the upper shoreface zone (elliot, 1986; clifton, 2006). size of detrital material and seeward inclination of cross-bedding show that coarse detrital material, together with rhodoliths and serpulids, was probably derived from shoreline, by back currents generated by exceptionally strong storms. bodies of sediments rich in fragments of bivalve shells chaotically distributed represent storm deposits. single coarse-grained body was probably formed during a very short time amount (about few hours?). erosive channels, perpendicular or oblique to the shoreline, probably created by local rip currents can also be seen. visible in exposures bodies and structures probably not represent all events which took place in this area as due to the strong erosion processes, which are suggested by preserved sedimentary structures, erosional surfaces specially, part of sediments was reworked by subsequent storms. gravel containing dunes, generated by strong storm current migrated generally seawards, but sporadic occurrence of landward inclined cross-bedding implies occasionally shore-ward movements of dunes. longshore currents played less important role than currents more and less perpendicular to the shoreline. sediments of fair weather, represented by medium scale cross bedding, are preserved only locally. the lack of trace fossils in the lower part of sequence could be en efect of conditions existing during that period (strong current and wave actions), which was probably unfavorable for development and/or preservation of epiand infauna (d’alessandro & bromley 1996). only at the end of the development of facies association b sequence, locally, in sheltered area, were formed favourable, calm habitats that allowed to develop and preserve extensive nets of thalassoinoides and skolithos. the coexistence of skolithos and thalassoinoides indicates moderate turbulence d’alessandro, loiacono & bromley (1993). mcilroy (2004) sugessts that it can be an effect of partially isolation of that area by bars. 3.3 facies association c, coarser fraction this facies association, that stretches eastward (seaward) from the previous one facies in the area of lido burrone up to punta fanfalo2 (fig. 1c), is dominated by coarse and medium-grained calcarenites, whose thickness not exceed 20 meters. generally the coarser fraction consists in shell fragments and the sediments typically present traces of echinoidea. direct relation to the facies association b is partly obliterated by faults (abate et al., 1995). the visible part of the sequence starts with a layer of calcirudite with rhodolithes and shell fragments, similar to those of facies association b, covered by thin calcarenite strata with trough cross laminations or ripple cross-lamination. inclination of cross-bedding structures is generally southwestwards and less common towards s-sse (punta burrone, western outcrop) and wsw (punta fanfalo, eastern outcrop). the main part of facies association c is characterized by occurrence of thick beds (up to two m) of thick-bedded calcarenites, often sub-horizontal laminated, mostly well-sorted, coarse to medium-grained with channels filled up by cross-bedded calcarenites (fig. 6a). there are also thick (up to 1 m) tabular crossstratified calcarenites, covered by ripple cross-laminated ones. locally, shallow (up to tens of centimeters deep) channels broad occur, filled-up by crosslaminated calcarenites (fig. 6a). several beds contain numerous dispersed shells of pectinids and echinoidea (see the upper part of fig. 6b) and, less commonly, of brachiopods, dentalium and cardium. molluscs in life position or forming layers of convex-up oriented bivalve shells (fig. 6c), together with fragments of echinoidea and – more rarely – rhodoliths, heve been observed in some oucrops (lido burrone, punta fanfalo). these organic remains may form lags above erosional lower surfaces (fig. 6d). in punta burrone area planar bifurcated structure, similar to mangrove tye roots (fig. 10h) have been discovered. this generally low-energy facies association, locally with mollusc shells in life position, was developed in relatively deep, quiet environment within shoreface zone. longshore currents from nne dominate, favouring 2 sediments similar to facies association c are also exposed in area of punta marsala. ślączka a. et al. 158 fig. 5 facies association b (uppershore zone), area di punta longa, south of town of favignana. a) conglomerate build up mainly of rhodolithes, cross-bedded in upper part. north towards the right. length of measure 1 m; b) local, concentration of shells of molluscs horizontally arranged. in lower part visible cross-bedding. length of penknife is 6 cm; c) massive calcarenite with poorly defined crosslamination covered by cross-bedded calcirudites, which pass landward into coarsegrained calcarenites. sharp bedding plane records storm period. note a fault on the right side of picture (f). length of measure 1 m; d) sub-horizontal, coarsening upwards calcirudites with pebbly lags and erosional upper surface overlain by seaward dipping coarse-grained and conglomeratic calcarenites strongly bioturbated. note vertical, scolithos type traces fossils. some of them penetrated the lower unit. less visible are thalassinoides developed on surface of the inclined layers – compare fig. 3g. pen for scale; e) sequence which started with calcirudites that contain rhodolithes and fragments of shell, covered by horizontal layers (f), passing upwards into oblique cross-bedded bioturbated calcarenite (cr) and topped by hummocky like (b) calcarenite. seaward inclination of laminae. length of pencil is 15 cm; f) a local channel (ch) in sub-horizontal coarse calcarenites with muddy matrix. this channel, 1,5 meters deep, is filled by stack of sinusoidal cross-bedded bodies incline landward. note patchy concentration of pebbles (e.g. near hammer). hammer for scale; g) thalassinoides network at the top of the sequence shown on fig.3d. note the thin layers of mudstone that are very rare in the study area; h) detail of thalassinoides network; i) ophiomorpha occur only sporadically. lower pleistocene deposits in east part of the favignana ... 159 the deposition of thin, tabular cross-stratified or horizontally laminated calcarenites. exceptionally, storm action reworked the sediments developing both massive calcarenites, with lags above erosive surfaces, or calcarenites with vertical sequence of tabular crossstratified and ripple laminations or erosive channels filled up by cross-bedded calcarenites. during colonization windows (goldring, 1991), planar trace fossils sets (cruziana facies) took place. facies association c represents low energy environment connected with a bar trough (clifton, 2006). sporadic appearance of very coarse sediments could be rather an effect of strong storms (elliot, 1986; clifton, 2006) while evolution of beach/nearshore facies could be linked with change of sea level (mateu-vicens, 2008). scattered occurrence of problematic mangrove type roots suggests shoal areas. 3.4 facies association d this facies association, characterized by the occurrence of tabular laminated cross-bedded calcarenites (figs 7, 9a), whose lower and upper surface of beds are erosive, with broad deep channels (figs 8, 10b) and abundant trace fossil of skolithos ichnofacies, is exposed, for a thickness that do not exceed 15 meters, along the northern island shore (frascia area), between the town of favignana and cala s. nicola (fig. 1c).the main facies, mainly developed in western (landward) part of association d (fig. 9a), is represented by thick bedded (up to 2 m) and coarse-grained calcarenites, with subhorizontal and large-scale cross-bedding. generally the lamination is emphasized by change of grain size and locally by lags of fragments of bivalve shells. locally laminae are pervasive bioturbated. the main feature of some cross-bedded strata shows a laminated-tobioturbated pattern, similar to described from pleistocene deposits of salento area by d’alessandro & massari, (1977). in few cases, only the lower part of each set of inclined laminae is bioturbated; somewhere bioturbation is pervasive. in some thick calcarenite beds, a vertical facies succession can be observed: from the base subhorizontal laminated calcarenites crop out, capped by cross-bedded calcarenites, locally wedgelike, whose top consists of strongly bioturbated calcarenites (fig. 10)3. generally, cross-bedding is inclined towards se, only locally toward w. the upper part of the facies association d shows typically the occurrence, particularly in more distal (seaward) part (fig. 9b), of broad (dozen or so meters) erosional channels and washouts (usually up to 2 m) (fig. 8): channels are filled-up or by massive calcirudites (fig. 10a) or by calcarenites with trough cross-lamination, partly destroyed by bioturbation. some calcarenites show crude concave or chaotic laminations and can pass into parallel laminated and cross-bedded calcarenites. exceptional deep channels (up to 5 m) have been observed in cala calamoni, se from the town of favignana; channels are filled by laminated calcarenites and massive calcarenites with scattered bivalve shells. direction of channels are generally n-s, (nw-se to ne-sw) and locally w-e4. facies association d is also characterized by the occurrence of scolithos ichnofacies (figs 10c-e, 11a), in some localities the scolithos-type traces cross the earlier bioturbated zones (fig. 10e); less common there are cruziana (thalassinoides and ophiomorpha) ichnofacies linked with the colonization windows. concentration of vertical burrows at the top of the bed is often observed (fig. 10d). mainly between punta s. nicola and madonna traces of echinoidea have been observed. in the central part of the island, near the town of favignana, in very thick cross-bedded and subhorizontal laminated calcarenites, several horizons with scolithos are observed (fig. 11a). locally, there are cluster burrows represented by straight radial tubes (few millimeters thick) and tens of cm long (fig. 10g), which resemble that traces which were made by colony of social insects (curran, 1992). the planar, radial and bifurcated structures (fig. 10h) can represent root system of plants. the presence of rooted plants in the pleistocene sediments 3 less common are thick-bedded calcarenites, with big scale through cross-bedding, locally, there are sets of bi-directional cross bedded bodies, lenses of mediumand fine-grained structurless calcarenites and intercalations of calcirudite represented generally by matrixsupported conglomerates with rhodoliths (few cm in size), fragment of shells (mainly bivalves, locally dentalium) and sporadic pebbles of mesozoic limestones. sporadically shells of bivalves (fig. 10a) and echinoidea are concentrated on surfaces of cross-bedding. 4 in some places, near the top of the beds, convolute laminations or single small conical forms are visible, the dimension of convolute raises several tens of cm (fig. 10b). locally, there are sets of small, rotated synsedimentary normal faults (fig. 11b). in few places small parallel dunes, 30 cm of width, which upper surface can be covered by scattered shells and rhodolithes, are locally developed on the upper surface of calcarenites. associazione di facies b (zona uppershore), area di punta longa, a sud della città di favignana. a) conglomerato costituito principalmente da rodoliti, a stratificazione incrociata nella sua parte superiore. il nord è verso destra. l’unità di misura è di 1 m; b) particolare, concentrazione di gusci di molluschi disposti orizzontalmente. nella parte inferiore è visibile la stratificazione incrociata. la lunghezza del temperino è 6 cm; c) calcarenite massiva con stratificazione incrociata mal definita ricoperta da calciruditi a stratificazione incrociata che passa verso terra a calcareniti grossolane. le superfici di strato registrano eventi di tempesta. si noti una faglia sul lato destro della foto (f). l’unità di misura è 1 m; d) calciruditi suborizzontali, a gradazione inversa con clasti maggiori isolati, troncati da una superficie di erosione sulla quale poggiano calcareniti grossolane e conglomerati, inclinati verso mare, fortemente bioturbati. si notino le tracce fossili verticali tipo scolithos. alcune di queste attraversano l'unità più bassa. meno visibili sono i thalassinoides sviluppati sulle superfici di strato inclinate – confronta la fig. 3g. vedi la penna per la scala; e) sequenza sedimentaria che inizia con calciruditi contenenti rodoliti e frammenti di gusci, seguiti da strati orizzontali (f), passanti verso l'alto a calcareniti a stratificazione obliqua, incrociata, bioturbate (cr) e ricoperte da calcareniti tipo hummocky (b). l’inclinazione delle lamine è verso il mare. la lunghezza della matita è 15 cm; f) canale locale (ch) nelle calcareniti suborizzontali grossolane con matrice pelitica. questo canale, profondo 1,5 metri, è riempito da un gruppo di corpi sinusoidali a stratificazione incrociata inclinati verso terra. nota la concentrazione di ciottoli (e.g. vicino il martello). vedi il martello per la scala; g) griglia di thalassinoides al tetto della sequenza mostrata in fig. 3d. nota gli strati sottili di peliti che sono molto rari nell'area di studio; h) dettaglio della griglia di thalassinoides; i) a luoghi vi è anche la presenza sporadica di ophiomorpha. ślączka a. et al. 160 fig. 6 facies association c (shoreface zone), area east of lido burrone. a) coarse grained, subhorizontal laminated calcarenite, partly eroded. cross-bedding of calcarenite that fills eroded part is inclined towards sw (height of wall around 2 m); b) horizontally laminated calcarenites with layers and patches of shells of moluscs in concave-upward position. note their imbrications. length of tape measure is 100 cm; c) horizontally laminated calcarenites covered by horizon of imbricated fragments of echinoidea shells and massive calcarenites with scattered fragments of shells. pencil for scale; d) upper surface of calcarenite covered by network of traces of echinoidea. length of tape-measure 100 cm; e) small, longshore channel (ch), 45 cm deep incised in medium bedded calcarenites that are crossbedded in the lower part and horizontally laminated in the upper part. length of note-book is 16 cm. associazione di facies c (zona di shoreface), settore orientale di lido burrone. a) calcarenite grossolana, a laminazione suborizzontale, parzialmente erosa. la calcarenite a stratificazione incrociata che riempie i settori erosi è inclinata verso so (l’altezza della parete è circa 2 m); b) calcareniti a laminazione orizzontale con livelli di frammenti di gusci di molluschi con la concavità rivolta verso l'alto. si noti la loro imbricazione. la lunghezza del nastro è 100 cm; c) calcareniti a laminazione orizzontale ricoperte da orizzonti costituiti da frammenti embricati di gusci di echinoidi e calcareniti massive contenenti frammenti sparsi di gusci. vedi la matita per la scala; d) superficie sommitale delle calcareniti coperta da una griglia di tracce di echinoidi. la lunghezza del nastro è 100 cm; e) piccolo canale parallelo alla linea di riva (ch), profondo 45 cm che incide gli strati calcarenitici caratterizzati da stratificazione incrociata nella porzione inferiore dell’affioramento e da laminazione orizzontale in quella superiore. la lunghezza del libretto è 16 cm. lower pleistocene deposits in east part of the favignana ... 161 fig. 7 facies association d. vertical facies succession started with subhorizontal laminated calcarenite with erosional top surface that is followed by wedge-like, seawards cross-bedded body and terminated by pervasive bioturbated part (colonization window). probably an effect of one storm. next succession starts with subhorizontal laminated calcarenite. frascia, east from town of favignana. associazione di facies d. successione verticale di facies: in basso calcareniti a laminazione suborizzontale troncate al tetto da una superficie erosiva. segue un corpo, con geometria cuneiforme, a stratificazione incrociata inclinata verso mare, ampiamente bioturbato nella parte terminale (colonizzazione a ”finestra”), probabilmente per effetto di tempesta. la rimanente parte della successione inizia con calcareniti a laminazione suborizzontale. località frascia, ad est dell’abitato di favignana. fig. 8 facies association d. stack of several successive channels filled or by cross-laminated calcarenites or by, massive calcirudites with dispersed pebbles. note that erosion removed practically all-preceding sediments. it clearly illustrates sediments of several exceptionally highenergy events. frascia, east from town of favignana. associazione di facies d. sequenza verticale di diversi canali riempiti o da calcareniti a laminazione incrociata o da calciruditi massive con ciottoli sparsi. nota che l’erosione ha praticamente rimosso tutti i sedimenti precedentemente deposti. ciò mostra chiaramente che si tratta di eventi deposizionali ad energia molto elevata. località frascia, est dell’abitato di favignana. fig. 9 facies association d (shoreface zone), a) large scale cross-bedded calcarenites and calcirudites dipping seaward. note the seaward decrease on angle of cross-beds (pointed by arrow). sparse sub-vertical burrows occur. area of frascia, near to town of favignana, exposure along the shoreline; b) laminated calcarenites inclined towards ese cut by two channels, one a broad filled by laminated coarse grained calcarenites (ch) and other younger, deeper, with steep wall filed up by massive debrite (d) that represent sediments of cohesive flow. direction of channels is generally w-e. note several vertical burrows of scolithos type (s). the uppermost part is strongly bioturbated (b). wall is 4 meters high. more distal of shoreline exposure then on fig. a. associazione di facies d (zona di shoreface), a) calcareniti e calciruditi, con stratificazione incrociata a grande scala, immergenti verso mare. da notare che l’inclinazione degli strati decresce verso mare (punta della freccia). a luoghi si rinvengono anche burrows subverticali. affioramento lungo la costa nell’area di frascia, vicino l’abitato di favignana; b) calcareniti laminate immergenti verso ese, incise da due canali, il più grande dei quali è riempito da calcareniti grossolane laminate (ch) mentre l’altro più recente e più profondo, è riempito da detrito massivo (d) che rappresenta il prodotto di un flusso sedimentario coesivo. la direzione dei canali è generalmente o-e. da notare anche la presenza di numerosi burrows verticali di tipo scolithos (s). la porzione più elevata della sezione è fortemente bioturbata (b). la parete è alta 4 metri. l’affioramento è più distante dalla costa rispetto alla fig. 9a. ślączka a. et al. 162 fig. 10 facies association d (shoreface zone) a) calcirudite with scattered molluscs shells. note increase of on angle of crossbedding toward left (landward). storm triggered sediments. penknife is 6 cm long; b) bending of laminated calcarenites due probably to synsedimentary folding connected with vertical movement of substratum. wall aprox. two meters high; c) set of vertical burrows of scolithos type that cut massive calcirudite. rucksack for scale; d) scolithos ichnogulid. note two sets of vertical trace fossils: older formed below upper erosional surface (colonization window) in calcarenite and younger in calcirudite that locally penetrated the lower calcarenite. length of tape measure 100 cm; e) totally bioturbated level cut by younger vertical burrows (vb). length of tape measure 100 cm; f) detail of a branched vertical burrow in calcarenite. penknife is 6 cm. long; g) bundle of vertical tubes that resemble a colony of insects. length of tape measure 50cm; h) structure on upper surface of calcarenite that resemble root traces, probably mangrove type of plant. pencil for scale. associazione di facies d (zona di shoreface) a) calcirudite con gusci di molluschi sparsi. si noti l’aumento dell’angolo di inclinazione verso sinistra (verso terra). deposito di tempesta. il temperino è lungo 6 cm; b) calcareniti con geometria curviforme dovute a piegamenti sinsedimentari connessi con le deformazioni verticali del substrato. la parete è alta circa 2 m; c) set di burrows verticali del tipo scolithos dentro la calcirudite massiva. per la scala vedi lo zaino; d) ichnofacies di scolithos. si notino i due set di tracce fossili verticali: il più antico si è formato nella calcarenite sotto la superficie erosiva superiore (finestra di colonizzazione) il più giovane, invece, dentro la calcirudite e localmente ha penetrato le calcareniti. la lunghezza del nastro è 100 cm; e) livello completamente bioturbato attraversato da burrows verticali più recenti (vb). la lunghezza del nastro è 100 cm; f) dettaglio di un burrow verticale e ramificato dentro la calcarenite. il temperino è lungo 6 cm.; g) fascio di burrows verticali che assomigliano ad una colonia di insetti. la lunghezza del nastro è 50 cm; h) struttura sulla superficie superiore delle calcareniti che assomiglia a una traccia di radice, probabilmente tipo mangrovia. vedi la matita per la scala. lower pleistocene deposits in east part of the favignana ... 163 were already noted by d’alessandro et al,. (1993) in the bradano trough (south apennines). in several places, calcarenites beds are cut by faults, some of which become extinct upwards within the sandbodies. depositional assemblages of sedimentary structures, existence of coarse lag of shell debris, lateral changes of facies, frequent channels, disorganized shell debrites sequences, similar to hummocky sequences of dott & bourgeois (1982), are characteristic for high-energy shoreface environment (clifton, 2006; elliot, 1986; wysocka, 2002). planar laminated sets reflect highest current velocities and covering them cross-bedded lenses the decreasing of energy conditions (cfr. clifton, 1976). the thick bedded, large-scale cross-beds of calcarenite and calcirudite, that developed in western part, near the town of favignana, with bioturbated intervals (cruziana ichnofacies), can represents remnants of shoreface zone with seaward prograding wedges (pomar & tropeano, 2001; mateu-vicens et al., 2008). more seaward part, with differentiated facies, relatively abundant washouts and channels and common skolithos ichnofacies probably represents inner bars system (bridge & demicco, 2008; clifton, 2006; davdson-arnott & greenwood, 1976). the prevailing ichnofacies, represented by skolithos ichnofacies, in this area represents more shallow conditions than cruziana ichnofacies (seilacher, 1967, pemberton et al., 1992). also, big-scale planar cross-bedded bodies, observed east of the town of favignana, with tiers of scolithos ichnofacies, can represent a local inner bar system generated by longshore currents. washouts and channels that cut the inner shoreface longshore bars were created by rip currents, generated from long shore ones (clifton, 1976-2006; davdsonarnott & greenwood, 1976). the channels size increased with magnitude of storm. occurrence of stacks of storm surge channels, cut through calcarenite beds and filled commonly by storm sedimentary breccias (storm lag deposit), are indicative of periods of frequent storms occurrence. very deep erosional channels, with sedimentary breccia that derived from the shoreline and transported seaward on distance almost 2 km, could be related to surges and debris flows (clark & pickering, 1996), generated by very high energy events (hurricanes and probably also tsunami tinti, 1993). the latter could be the effect of submarine earthquakes, generated by local tectonic movements that existed during late pleistocene. vertical changes of bioturbation characters (pervasive bioturbation and skolithos type) can represent water depths changes, generated by synsedi fig. 11. continued facies association d. a) vertical stacking of subhorizontal and low-angle laminated calcarenites with abundant vertical burrows (s) and pervasive bioturbated horizons (b). penknife (white) is 6 cm long. cala calamoni, abandoned quarry on west outskirts of the town of favignana town; b) sequence of parallel laminated coarse grained calcarenites that rest on the flat symmetrical dune (d) around 30 cm high. note normal synsedimentary fault system at the top of the lower layer. penknife (black) is 6 cm long. another part of the same quarry as on fig.7a. continua associazione di facies d. a) sequenza verticale di calcareniti con laminazioni suborizzontali ed a basso-angolo, con abbondanti burrows verticali (s) ed orizzonti ampiamente bioturbati (b). il temperino è lungo 6 cm. cala calamoni, cave abbandonate alla periferia ovest della città di favignana; b) sequenza di calcareniti grossolane a laminazione parallela, espressione di parte di una duna simmetrica e piatta (d) alta circa 30 cm. da notare la presenza di un sistema di faglie dirette sinsedimentarie normali al tetto dello strato più profondo. il temperino è lungo 6 cm. altro settore della cava di fig. 7a. fig. 12 facies association e. a) vertical stacking of several horizontal and crosslaminated calcarenites that continue over a length of tens of meters, separated by subhorizontal surfaces represented probably temporary wave base levels. note a huge channel on the left side of the picture, deep more than 10 meters, it is filled up by massive calcirudites. slope lithofacies. cliff below cala torretta, nw from calarossa; b) detail of fig. 12a. note a vertical stacking of double sandbodies that are represented by horizontal and cross-laminated calcarenites. cross-lamination dipping to se (seaward), ch = channel. associazione di facies e. a) successione verticale di calcareniti a stratificazione orizzontale e a laminazione incrociata continua per decine di metri, separata da superfici suborizzontali che probabilmente rappresentano temporanei livelli di base delle onde. da notare un canale di notevoli dimensioni sul lato sinistro della figura, profondo più di 10 metri, riempito da calciruditi massive. litofacies di scarpata. cala torretta, a no di calarossa; b) dettaglio di fig. 12a. si noti la successione verticale dei corpi sabbiosi costituiti da calcareniti a stratificazione orizzontale e a laminazione incrociata, inclinata verso se (mare), ch = canale. ślączka a. et al. 164 fig. 13 facies association e (lower shoreface zone with bar system). area between torretta and bue marino. a) lower part of the association e. sequence started by fine-grained calcarenites (fc) followed by subhorizontal laminated calcarenites (h and set of bidirectional cross-bedded calcarenites covered by horizontal layers coarse grained calcarenites partly pervasive bioturbated (b). cross lamination is inclined to s and nw. that sequence show resembles to facies association c. punta marsala; b) lower part of facies association e. sequence started with parallel laminated calcarenites (l) overlaid by cross-bedded zone (t) that have oblique to sigmoidal stratification facing sw (shoreward), and terminated by set of medium scale trough cross-bedding (b) resembling hummocky crossbedding, with bioturbated horizons. note flat dunes. probably crest or landward slope part of an outer bar. cliff in calarossa; c) detail of fig. 12a that show internal architecture of cross-bedded facies. note the diminishing inclination of cross-lamination on lee side of dunes (white arrow); d) sequence of medium to large-scale bi-directional tabular cross-bedding calcarenite bodies. bue marino; e) synsedimen lower pleistocene deposits in east part of the favignana ... 165 mentary tectonic activity, as well as by sea level changes. they were also responsible for temporary appearance of very shallow environments, that are suggested by occurrence of traces of mangrove type root system and sub-aerial dunes with cluster burrows, which are regarded as insects burrows (curran, 1992). development of synsedimentary faults, escape of water structures was also triggered by tectonic activity, as suggested by synsedimentary, meters-in-scale, folds and convolutions (lowe, 19751976). however, some of them, that developed within gently inclined foreset crosslamination, could be also generated by local slumps (łaptas, 1992). the general lack of sediments with structures that represent fair-weather conditions (finegrained sediments, oscillation small-scale cross bedding) may be an effect of bottom erosion during successive storm (clifton, 1976). a more outer part of facies association d, observed near capo s. nicola, where traces of echinoidea appear, can represents a local phenomenon or more deeper part of shoreface. it shows similarity to facies association c. direction of inclination of cross laminations within facies association d document that calcareous sand was transported generally southeastwards, obliquely to the shoreline. seaward transport was less common. landward sand transport from reworked more distal bars is now visible only locally. 3.5 facies association e the lowermost part of this facies association, whose contact with the underlying facies association d is sharp, starts or with a layer (tens of cm thick) of broken shells, covered by cross-bedded calcirudites seaward dipping (cala canaleddi), or with a thick, homogenous bed of calcarenite covered by a tabular cross bedded interval that close with a pervasive bioturbated layer (calarossa).the thick sequence of large-scale cross-bedded and subhorizontal laminated bedforms are the most characteristic feature of this association (fig. 12), outcropping in the easternmost part of the favignana island, between the localities of cavallo and bue marino; the facies thickness reaches more than tary conical structures (a) of different size probably created by escape of water. bioturbated horizon (b) pinching out towards one of these structures. at the top of subhorizontal there is a sequence of bi-directional foresets. torretta, calarossa; f) uppermost part of the bar sequence, parallel laminated in the lower part and large scale crossbedded in the upper part. inclination of foresets is seaward. note bioturbated horizon (b) in the lower part of the photograph. cala fossofelle. associazione di facies e (shoreface suddivisa da un sistema di barre). area tra torretta e bue marino: a) porzione più profonda dell'associazione e. inizia con calcareniti molto fini (fc) seguite da calcareniti a laminazione suborizzontale (h) e da un set di calcareniti a stratificazione incrociata bi-direzionale ricoperto da strati orizzontali di calcareniti grossolane, a luoghi bioturbate in maniera pervasiva (b). la laminazione obliqua è inclinata verso s e no. la sequenza è simile all'associazione di facies c. punta marsala: b) parte più profonda dell'associazione di facies e. inizia con calcareniti a laminazione parallela (l) ricoperte da un intervallo a stratificazione incrociata (t) che possiede una stratificazione da obliqua a sigmoidale verso so (mare), e termina con un gruppo di corpi a stratificazione incrociata (b) simili a stratificazioni gibbose (hummocky), con orizzonti di bioturbazione. si noti la presenza di dune piatte. probabilmente la cresta o il lato interno costituivano parte di una barra esterna. scogliera di calarossa; c) dettaglio di fg. 12a che mostra l’architettura interna della facies a stratificazione incrociata. si noti che l'inclinazione della stratificazione incrociata diminuisce sul lato di protezione delle dune (freccia bianca); d) sequenza di corpi calcarenitici tabulari a stratificazione incrociata bi-direzionale a media-grande scala. bue marino; e) strutture coniche sinsedimentarie (a) di diversa taglia, probabilmente effetto di fughe d’acqua verso l’alto per improvviso carico sedimentario. orizzonte bioturbato (b) che si rastrema verso una di queste strutture. al tetto del corpo sub-orizzontale vi è una sequenza di foresets bidirezionali. torretta, calarossa; f) parte più elevata della sequenza di barra, laminazione parallela nella parte più bassa e stratificazione incrociata a grande scala nella parte superiore. l’inclinazione dei foresets è verso mare. si noti l’orizzonte di bioturbato (b) nella parte più bassa della fotografia. cala fossofelle. fig. 14 top of a bar with medium-sized dunes at the top (d, arrows) with foreset inclination oblique to paleo-shore line. lower part of facies association e. calarossa. top di una barra seguita da dune di medie dimensioni (d, frecce) con inclinazione dei foreset obliqua rispetto alla paleolinea di riva. parte più bassa dell'associazione di facies e. calarossa. fig. 15 stack of erosional channels (1-4) filled by laminated calcarenites. arrow indicates slumped block (sl) of a normal synsedimentary fold. note that sedimentary structures in slumped block are only partly disintegrated. current directions generally perpendicular to the face of photograph. facies association e. punta s. vituzzo. pila di canali erosivi (1-4) riempiti da calcareniti laminate. la freccia indica un blocco scivolato (sl) di una piega sinsedimentaria. si noti che le strutture sedimentarie nel blocco scivolato sono disintegrate solamente in parte. le direzioni delle correnti sono generalmente perpendicolari alla fotografia. associazione di facies e. punta s. vituzzo (cala rossa). ślączka a. et al.   166 fig. 16 higher part of the lower pleistocene sequence started with large cross-bedded calcarenites that dipping to nw (landward) covered by calcarenite with low angle seaward dipping lamination and by set of cross-bedded calcarenites with at least two orders of bounding surfaces. upper surface of this set is erosional and covered by thick sand body with subhorizontal lamination that terminated by ripple laminated calcarenites (r). note that bioturbation in cross-bedded calcarenite, on the right side of the picture, marked by letter b, disappears to the left, in more elevated part. facies association e, upper part of a bar system. cala fossofelle, case di vita. parte più elevata della sequenza del pleistocene inferiore che inizia con calcareniti, a stratificazione incrociata a grande scala immergenti verso no (verso terra), ricoperte da calcareniti laminate debolmente immergenti verso mare e da un gruppo di strati di calcareniti a stratificazione incrociata. la superficie superiore di questo gruppo di strati è erosiva ed è ricoperta da uno spesso corpo sabbioso con laminazione suborizzontale che termina con calcareniti laminate con strutture da ripple (r). si noti che la bioturbazione nelle calcareniti a stratificazione incrociata, sul lato destro della figura marcato dalla lettera b, scompare verso sinistra nella parte più elevata. associazione di facies e, parte superiore di un sistema di barra. cala fossofelle, case di vita. 40 meters in cavallo-torretta area. this facies in calarossa and cala canalleddi area rest directly on the uplifted lower pliocene marls (abate et al., 1995-1997) or sediments similar to facies association c5. the main part of this facies is built of thickand very thick-bedded sequences of, coarse-grained calcarenites, with subhorizontal and/or low angled lamination, and of calcarenites with large-scale cross-bedding (figs 12, 13b,f). calcarenites with hummocky cross-lamination (fig. 13b, uppermost part) also occur. seawardand landward-directed, as well as shore-parallel, sets of cross bedding are observed (fig. 13 b, d, and e)6. the majority of calcarenite beds presents lower and upper sharp, erosional surfaces. however, locally higher horizontal laminated bedform rest on non-eroded rippled upper surface of the lower bed. calcarenite beds form bodies long some of tens of meters, each gradually wedging out; lateral changes of facies have been observed. locally, asymmetric, cross-bedded mega-ripples (few tens centimeters high and several meters long) are preserved (fig. 14). also, symmetrical sandwaves (up to 50 cm high and several meters of length), built-up of homogenous sand have been observed on the top of horizontal laminated calcarenites. in more western (landward) part (torretta area), visible fragment of facies association sequence two, almost flat, erosional surfaces divide into three parts (fig. 12a) each calcarenitic body. each part shows complex internal structures; particularly the middle one consist in subhorizontal stack and in cross-bedded sandbodies (fig. 12b). this organization is preserved on distance of tens of meters, with local landwards opposite direction of cross-bedding. at calarossa and bue marino localities, the outer part of calcarenite body is characterized by cross-bedding dipping both landwards (fig. 13b, c), as well seaward (figs 13b-f, 14 and 16). somewhere, single or sets of medium-sized conical or diapiric structures can be observed at the top of horizontal laminated body (fig. 13e). crossand horizontal-bedded calcarenites are cut by several channels, generally filled up by crosslaminated bodies (fig. 13e); locally, stacks of channels are visible (fig. 15). a small synsedimentary slump was formed along the wall of channel (fig. 15). in topmost part of the sequence there broad channels filled by cross stratified bodies have benn observed (left part of fig. 13f and fig. 16), locally the filling shows lags of pebbles and rhodolithes or of debrites at the bottom, graded in their lower portion and containing scattered rhodolithes and shell fragments. along the western boundary of cavallo locality exceptionally large and deep channels were developed: one of them, more than 10 meters deep, is infilled by homogenous calcarenites (fluxoturbidite type; ślaczka & thompson, 1981); another one, tens of meters broad and more than 15 meters deep, is visible along the northern cliff of the same locality (fig 12a). intercalation of layers of pervasively bioturbated calcarenites (from dozen centimeters to one meter thick) occurs locally (fig. 13a, b, and f). a typical feature of some cross-bedded bodies consists in laminated-to-bioturbated pattern, similar to those described by d’alessandro & massari, (1997): normal and bioturbated laminae are alternate (fig. 13c). in some cases, only a lower part of inclined laminae shows bioturbations (figs. 13e and 16). sporadically, traces of echinoidea occur in the lower part of the sequence. scolithos-type of burrows is extremely rare and occurs in higher part of the sequence. bioturbation disappear in the highest part of the sequence (torretta). coarse-grained and conglomeratic sandbodies, occurring in the lowest part of facies association, more than two kilometers from the ancient shoreline, probably represent storm-reworked beds, redeposited from the shoreline and distributed on the shallow shelf, east from paleo-favignana island, by high energy currents. the main part of facies association e consists of mixed facies of thick and very thick bedded, planar or crosslaminated, sandbodies, showing often characteristic fa cies succession from planar and/or crossbedded to hummocky-like and/or medium trough cross-lamination, bounded by unconformity with local channels represents the outer part of shoreface zone, marked by offshore bars/ridges system related to storm high-energy epi 5 in punta marsala where facies association e is underlayed by facies association c the profile starts with trough cross-bedded finegrained calcarenite, horizontally laminated, fine-grained muddy calcarenites (fig 13a), with traces of echinoidea, covered by layer (up to 50 cm thick) built-up of shell fragments covered by several meters calcarenite, generally pervasive bioturbated. 6 locally, in elongated lens-like bodies, laminae are sinusoidal, and cross-bedded sandbodies form tabular cossets. the ripple crosslaminated bodies (up to 1.5 m thick) locally rest on tabular cross-stratified or horizontal laminated sandbodies. lower pleistocene deposits in east part of the favignana ... 167 sodes (bridge & demicco, 2008; clifton, 2006; elliot, 1986; johnson & baldwin, 1986). long lasted, wind-induced currents deposited thick, seaward-dipping crossbedded calcarenites, spreading out on distance of hundreds meters. a submarine bar system, probably developed along an uplifted block of the pre-pleistocene platform and run generally from north towards south. stacks of bedforms with subhorizontal lamination and through cross-bedding dipping seaward and landward, with decrease of bioturbation and occurrence of erosional channels, can be regarded as crest part of bar facies, similar to suggestion of davidson-arnott & greenwood (1971). seaward slops of bars are probably represented by a sequence, where number of bioturbated bedforms and sets of small scale trough increase in number and where generally the planar bedding dips seawards. this successions are exposed in bue marino area, in the easternmost part of the favignana island. occurrence of layers, with offshore and onshore dipping sets of cross-bedding, shows on periodical migration of dunes seaand shoreward by wave induced currents, but seaward movements predominated. the magnitude and direction of all of these currents was varying during weather and long-term sea-level changes, and was also connected with vertical tectonic movements. it can be suggested that the observed bedforms were generated by giant long periods waves and by related surges, such as those generated by propagation of hurricanes and/or tsunamis into shallow water areas (d’alessandro & massari, 1997; tinti, 1993). periods of high wave energy were interrupted by fair weather periods, during these latter wave cross-ripple beds develop and the sea bottom was colonized by burrow animals of cruziana ichnofacies while the upper part of deposited bedforms was intensively bioturbated. the occurrence of bioturbation suggests favorable conditions only in lower part of foreset laminae thus suggesting the persistence of a sea depth useful for a better concentration of food. on the contrary the uppermost part of sequence, totally devoid of trace fossils, can represents facies of short duration aeolian dune. considerable thickness of facies association (over … m), the lacking of distinct changes of facies in vertical profile and of distinct progradation suggest a fault-induced lowering of this part of offshore area. flat erosional surfaces near cavallo area show similarities to shoreface erosion planes described by elliot (1986): temporary tectonic uplift could be create an effect of sea-level changes of a part of the shelf, thus increasing the erosion by wave actions: it removed clastic material from higher part of the uplifted bar toward deeper sea. 4. conclusions the distribution of bedforms, sedimentary structures and ichnofacies allow to distinguish eastwards from shoreline of paleo-favignana island several characteristic facies associations connected with foreshore/shoreface (f a a), upper shoreface (f a b), upper/middle shoreface (f a d) and lower shoreface (f a e) depositional zones with a system of inner bars (f a d p.p.) and outer bars (f a e p.p.) parallel or oblique to the shoreline separated by trough (f a c) (fig. 17-18). widely distribution washouts, rip channels and sediments of tractional currents in all facies associations suggest deposition above wave-base level. temporary developed partly emerged dunes have been recognized. only negligible part of clastic material was derived from erosion of uplifted part of paleo-favignana island that probably had greater northward extension, however bulk of the bioclastic material accumulated on favignana inner shelf originated from shoreline material and is composed of debris from molluscs, calcareous red algae, bryozoan, foraminifera, etc. the main role in distribution of clastics was played by storms that induced strong and very strong longshore currents along the shoreline: these currents were shunted offshore and cut and filled channels across the bars. landward movement of clastic fig. 17 a model of currents distribution and facies associations, east from paleofavignana island. prevailed southward longshore currents. scale bar dimension is approximate. vertical scale is roughly estimated. modello della distribuzione di correnti e delle associazioni di facies ricostruite per il settore orientale della paleo-isola di favignana, caratterizzata dalla prevalenza di correnti dirette verso sud parallele alla riva. le scale, orizzontale e verticale, sono approssimative. fig. 18 schematic profile of facies distribution in shoreface zone east from favignana island with two bar systems. profilo schematico della distribuzione delle facies di spiaggia nel settore orientale dell’isola di favignana, con evidenziati i due sistemi di barra. ślączka a. et al. 168 material and the development of megarippled dunes has been observed locally, due to high energy landwards waves. during tsunami-related high-energy events scattered large erosional structures were probably formed. similar events triggered local debris flows. storm-generated sedimentation units are underlined by the erosion surfaces on which some channels, up to tens meter wide and several meters deep took place. besides storm wind-induced currents were active producing longshore and rip currents that deposited seaward dipping crossbedded calcarenites which spread out on distance of hundreds of meters. the storm periods were separated by fair weather intervals: cross-ripple beds were colonized by population of burrowing organisms thus producing pervasive bioturbation. the bioturbated deposits were frequently eroded by series of storms. during intense storm the erosion cut deeper part of dunes and episodic, low angle dipping surfaces;. the development of such erosional surfaces was also controlled by uplifting of the substratum and by relative change of the sea level. synsedimentary strike-slip tectonics were besides reported for favignana area. the relevant thickness of the facies association e, more than 40 meters, also suggests a generalized fault-induced downward movements of the substratum7. typical vertical and lateral sequences of sedimentary structures in storm deposits were represented by subhorizontal lamination succeeded by about-planar cross-bedding, hummocky type cross stratification or/and rarely wave ripple lamination. the top of sequence is often bioturbated, as an effect of recolonization by fauna during fair weather. the recognized facies associations also differ in ichnofacies content: in fa a ichnofossils are rare and mainly represented by short vertical tubes; in fa b wide areas are colonized by thalassinoides and, more rarely, by vertical burrows (cruziana and skolithos ichnofacies); in fa c traces produced by echinoidea; in fa d skolithos ichnofacies and horizons pervasively bioturbated are common, locally cluster of insects burrows have been oberved; in fa e trace fossils are rare and are limited to few traces of echinoidea and some vertical burrows, while pervasive bioturbated horizons are common. the recognized facies associations also differ in ichnofacies content: in fa a ichnofossils are rare and mainly represented by short vertical tubes; in fa b wide areas are colonized by thalassinoides and, more rarely, by vertical burrows (cruziana and skolithos ichnofacies); in fa c traces produced by echinoidea; in fa d skolithos ichnofacies and horizons pervasively bioturbated are common, locally cluster of insects burrows have been oberved; in fa e trace fossils are rare and are limited to few traces of echinoidea and some vertical burrows, while pervasive bioturbated horizons are common. references abate b., incandela a. & renda p. (1997) carta geologica delle isole di favignana e levanzo dipartimento di geologia e geodesia, univ. palermo. abate b., ferruzza g., incandela a & renda p. (1995) tettonica trascorrente nelle isole egadi sicilia occidentale studi geologici camerti, vol. spec. 2, 9-14. abate b., incandela a. & renda p. & slascka a. (1999) -shoreface deposits and ichnofacies, favignana, sicily. in: clemmensen l. b. (ed) abs. vol. 19th regional european meeting of sedimentology, copenhagen 24-26 august, 1999, 2. bridge j. & demicco r. (2008) earth surface processes, landforms and sediment depositscambridge university press. pp. 815. bromley r.g. (1996) trace fossils chapman & hall, london: pp. 361. catalano r., di stefano p. sulli a. & vitale f.p. (1966) paleogeography and structure of the central medi-teranean: sicily and its offshore area tectonophysics 260, 291-323. clark j.d. & pickering, k.t. (1996) submarine channels, processes & architecture vallis press, london, pp. 231. clifton h.e. (1976) wave-formed sedimentary structures: a conceptual model in: davis jr., r.a. & ethington r. l. (ed.) beach and nearshore deposits. society of economic paleontologists and mineralogists, spec. pub. 24, 126-148. clifton h.e. (2006) a reexamination of facies models for clastic shorelines sepm spec. pubbl., 84, 293-337. curran h.a. (1992) trace fossils in quaternary, bahamian-style carbonate environments: the modern to fossil transition in c.g. maples & r.r. west (eds.), trace fossils. short courses in paleontology, the paleontological society, knoxville, 5, 105-120 d’alessandro a. & bromley r.g. (1986) trace fossils in pleistocene sandy deposits from gravina area, southern italy rivista di paleontologia e stratigrafia 92, 67-91. d’alessandro a., loiacono f. & bromley r.g. (1993) marine and nonmarine trace fossils and plant roots in regressional setting (pleistocene, italy) riv. ital. paleont. strat., 98, 495-522. davidson-arnott r.g.d. & greenwood b. (1976) facies relationships on a barred coast, kouchibouguac, new brunswick, canada in: davis jr., r.a. & ethington r. l. (ed.) beach and nearshore deposits. society of economic paleontologists and mineralogists, spec. pub. 24, 149-168. dott r.h. & bourgeois j. (1982) hummocky stratification: significance of its variable bedding sequences bull. geol. soc. of amer., 93, 663-680. elliot t. (1986) siliciclastic shorelines in: h.g. reading (ed.) sedimentary environments and facies, blackwell scientic publications, 155-188. fox w.t. & davis jr. r., a. (1976) weather patterns and costal processes in: davis jr., r.a. & ethington r.l. (ed.) beach and nearshore deposits. society of economic paleontologists and mineralogists, spec. pub. 24, 1-23. goldring r. (1991) fossils in the field longman, harlow. incandela a. (1995) lineamenti stratigrafico-strutturali dell’estremità nord-occidentale della sicilia e delle 7 also locally observed sharp differences in thickness and facies between facies associations could be fault-induced, as proposed for similar phenomena in upper cretaceous shelf sandstones in sudetes by wojewoda (1986). lower pleistocene deposits in east part of the favignana ... 169 isole di favignana e levanzo (arcipelago delle egadi) tesi di dottorato. palermo incandela a. (1996) deformazioni neogeniche nelle isole di favignana e levanzo (isole egadi) mem. soc. geol. it., 51, 129-135. johnson m.e. (2002) paleoislands in the stream: paleogeography and expected circulation patterns geobios, 35, 457-476. johnson m.e.& baldwin c.t. (1986) shallow siliciclastic seas in: h.g. reading (ed) sedimentary environ ments and facies, blackwell scientic publications, 229-282. lowe d.r. (1975) water escape structures in coarsegrained sediments sedimentology, 22, 157-204. lowe d.r. (1976) subaqueous liquefied and fluidised sediment flows and their deposits sedimentology, 23, 285-308. łaptas a. (1992) giant-scale cross-bedded miocene biocalcarenites in the northern margin of the carpathian foredeep ann. soc. geol. poloniae, 62, 149-167. raaf j.f.m., de boersma j. r. & gelder a.v. (1977) wave generated structures and sequences from a shallow marine succession. lower carboniferous. county cork. ireland sedimentology, 4, 1-52. mcilroy d. (2004) some ichnological concepts, methodologies, applications and frontiers in: mcilroy, d. (ed.) the application of ichnology to paleoenvironmental and stratygraphic analysis. geological society, spec. pubbl., 228, 3-27. seilacher a. (1967) bathymetry of trace fossils marine geology 5, 413-428. malatesta a. (1955) risultati preliminari del rilevamento in sicilia e nelle isole egadi boll. serv. geol. it., 76, 517-521. massari f. & chiocci f. (2006) biocalcarenite and mixed-cool water prograding bodies of the mediteranean pliocene and pleistocene: architecture, deposirional setting and forcing factors geological society, london, special publications 255, 95120. massari f. & parea g.c. (1988) progradational gravel beach sequences in a moderate to high-energy, microtidal marine environment sedimentology, 35, 881-913 mateu-vicens g., pomar l. & tropeano m. (2008) architectural complexity of a carbonate transgresive systems tract induced by basement physiography sedimentology, 55, 1815-1848. nigro f. & renda p. (2001) late miocene-quaternary stratigraphic record in the sicilian belt (central mediterranean): tectonics versus eustasy boll. soc. geol. it., 120, 151-164. pemberton s.g., mac earchern j.a. & frey r.w. (1992) trace fossil facies models environmental and allostratigraphic significance in: walker, r.g. / james n.p. (eds) facies models response to sea level change, geological association of canada: 47-72. pettijohn f.j., pottr p.e. & siever r. (1987) sand and sandstone springer-verlag. pp. 553. pomar l. & tropeano m. (2001) the calcarenite di gravina formation in matera (southern italy): new isights for coarse grained, large-scale, cross-bedded bodies encased aapg bull., 85, 661-689. seilacher a. (1967) bathymetry of trace fossils marine geology, 5, 413-428. slascka a. & thompson s. (1981) a revision of the fluxoturbidite concept based on type examples in the polish carpathian flysch ann. soc.geol. poloniae, 51, 55-75. sulli a. (2000) structural framework and crustal characteristic of the sardinia channel alpine transect in the central mediterranean tectonophysics, 324, 321-336. tinti s. (1993) evaluation of tzunami hazard in calabria and eastern sicily, italy in. s. tinti (ed.) tsunamis in the world. kluwer, 141-157. tropeano m. & sabato l. (2000) response of pliopleistocene mixed bioclastic temperatewater carbonate systems to forced regression: the calcarenite di gravina formation. puglia se italy in: d. hunt & gawthorpe, r.l. (eds) sedimentary responses to forced regressions. geol. soc. of london, spec. pubbl., 172, 217-243. wojewoda j. (1986) fault-scarp induced shelf sand bodies: turonian of the intrasudetic basin in: eisseyre, a.k. (ed), ias 7th european regional meeting kraków-poland. excursion guiebook. may 1986, 31-52. wysocka a. (2002) clastic badenian deposits and sedimentary environments of the roztocze hills across the polish-ukrainian border acta geologica polonica, 52, 535-561. ms. ricevuto il 29 gennaio 2010 testo definitivo ricevuto il 25 marzo 2011 ms. received: january 29, 2010 final text received: march 25, 2010 sess 1_160211.pub il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 climatic and environmental changes of the santa gilla lagoon (cagliari) during the holocene anna maria porcu, antonietta cherchi, paolo e. orrù & paola pittau dipartimento scienze della terra, università degli studi di cagliari corresponding author: a. m. porcu <anna33146@hotmail.com> abstract: porcu a. m. et al., climatic and environmental changes of the santa gilla lagoon (cagliari) during the holocene. (it issn 0394-3356, 2011) through the study of two boreholes was possible to reconstruct the environmental and climate evolution of the last 10,000 years b.p. of the santa gilla lagoon. the data obtained are based on microfauna and palynomorphs analysis, integrated with geochemical analysis carried out on foraminifera calcareous shells. radiometric analysis were also performed to obtain a well-defined geochronology scale of sedimentary succession. riassunto: porcu a. m. et al.: variazioni climatiche e ambientali della laguna di santa gilla (cagliari) durante l’olocene. (it issn 0394-3356, 2011) attraverso lo studio di due sondaggi a carotaggio continuo è stato possibile ricostruire l’evoluzione ambientale e climatica degli ultimi 10.000 anni b.p. della lagna di santa gilla. i dati ottenuti sono basati sull’analisi della microfauna e dei palinomorfi, integrati con analisi geochimiche effettuate sui gusci calcarei dei foraminiferi. sono state inoltre compiute analisi radiometriche per ottenere una scala geocronologica ben definita della successione sedimentaria. keyword: foraminifera, palynology, stable isotope analyses parole chiave: foraminiferi, palinologia, analisi isotopiche  multidisciplinary study on the marine and continental microfacies from two boreholes of the santa gilla lagoon allowed to reconstruct the environmental, climate and vegetation changes that occurred in the gulf of cagliari during the holocene. palynologic (pollen and spores analyses), micropaleontologic (benthic foraminifers) and isotopic data (δ18o and δ13c) over the past 10.000 years b.p. from this transitional-coastal sequence show a series of shift leading to the establishment of different climatic conditions. the investigated archives included lagoonal organic shales, posidonia peat and coastal, fine and medium sandstone. radiocarbon dating and multiproxy analyses were performed on 30 meters of succession. the radiometric analysis allowed to date the sedimentary series, placing the beginning of the lagoon silting process from moments immediately after the younger dryas (orrù et al., 2004; antonioli et al., 2007) and to compare the sedimentary succession to the northern european chronostratigraphy. the coastal sediments are the reservoir of biological and lithological information on mutual relations continent-sea. any sea level change, both eustatic and isostatic and tectonic, left its marks on the fossil faunal and microfaunal composition. through the foraminifera study and according to the knowledge on their ecology (sgarella & moncharmont zei, 1993; cimerman & langer, 1998; fiorini & vaiani, 2001), have been detected environmental characteristics that have occurred during the lagoon filled. benthic foraminifer association were identified and assembled into five main eco-groups that have shown the transition from lagoonal environment (10.000-9.000 years b.p.) to marine sublittoral with a very close lagoon (9.0003000 years b.p.) and then return to the lagoonal but with marine influences (3.000-250 years b.p.) and re-opened to the sea (250 years b.p.-actual). any climatic change, if it exceeds a certain threshold, gives a change in the vegetation which is recorded in coeval sediments by the palynological record. the sequence of sporo-pollen spectra provides the vegetation evolutionary pattern of the source area of the studied basin. the palynological study allowed the vegetation spectra reconstruction (reille, 1992; reille, 1995; reille, 1999) showing five phases and a sub-phase, marked by an appreciable evolution in terms of frequency curves that represent the stages of the vegetation dynamics of last 10,000 years under the climate influence. the vegetational response to the amelioration of the climate in the early holocene (9.800 -7.600 years b.p.) resulted in the spread of the ericaceae macchia (first phase) and the setting of the quercus forest between 7.700-7.600 years b.p. (sub-phase). this was followed by a shift toward drier and more open vegetation mainly represented by chenopodiaceae (second phase) at 7.600-7.200 years b.p. at 7.200-4.800 years b.p. a more persistent peak in deciduous quercus values signal a reestablishment of wetter conditions and the maximum extension of the quercus forest (third phase). alternated drier (chenopodiaceae) 51 53 52 f ig .1 , g eo ch ro no lo gi ca l, ch ro no st ra tig ra ph ic , o f t he p al eo te m pe ra tu re s, p al eo ve ge ta tio n, p al eo en vi ro nm en ta l, an d pa le oc lim at ic s ch em e of th e st ud ie d su cc es si on s. s ch em a ge oc ro no lo gi co , c ro no st ra tig ra fic o, d el le p al eo te m pe ra tu re , p al eo ve ge ta zi on al e, p al eo am bi en ta le , e p al eo cl im at ic o de lle s uc ce ss io ni s tu di at e a.m. porcu et al. 53 ms. received: testo ricevuto il and wetter phase with developpement of quercus orest even in the coastal plains followed. the last chenopodiaceae arid and cold phase (fifth phase) fitted with the little ice age (216±100 years b.p.). because eustatic changes are not always depend on climate, but climate change almost always produce eustatic changes, the integrated study of microfauna and continental flora provides a much valuable investigation means in the evolution reconstruction of coastal areas and climate evolution of a region. climate change producing water temperature and salinity variations, which are recorded in the lagoon from microfaunas through the relation changes of oxygen and carbon isotopes. the isotopic analysis (δ18o and δ13c) were carried out on the shells of two species of foraminifera, ammonia tepida and elphidium granosum, good indicators of lagoon and estuarine environments (cronin et al., 2005). were obtained two types of scales for each species: a multi-decadal scale and a multi-centennial scale, obtained by the method of 5-point running average. the long-term variability of δ18o values (multi-centennial, 200400 years, time-scales) indicate a variable positive trend from 9.450 to 7.500 years b.p. approximately, and a negative trend from approximately 7.100 to 2.000 years b.p. the multi-centennial time-scale of the δ13c values indicates a variable decreasing negative trend from 10.00to 7.700 years b.p., that we regard reflecting increasing salinity waters culminating with the remarkable marine rising of the holocene optimum climaticum. higher δ13c negative values from 7.500 to 3.850 years b.p. are regarded as indicative of higher precipitation with higher organic influx of terrestrial origin; whereas the succeeding higher δ13c values up to 1.850 a.d. are indicative of increasing water salinity. variable amplitude fluctuations at multi-decadal time-scale, 20-30 years, are superimposed on these long-term trends.     references antonioli f., anzidei m., lambeck k., auriemma r., gaddi d., furlani s., orrù p.e., solinas e., gaspari a., karjnja s., kovačić v. & surace l., (2007) sea level change during the holocene in sardinia and in the north-eastern adriatic (central mediterranean sea) from archaeological and geomorphological data. quarternary science review 26, 2463 –2486. cimerman f. & langer m. r. (1991) mediterranean foraminifera ljubljana, slovenska akademia, 118 pp., 93 pls. cronin t. m., thunell r., dwyer g. s., saenger c., mann m. e., vann c. & seal r. r. (2005) – multyproxy evidence of holocene climate variability from estuarine sediments, eastern north america. paleocenography, 20. fiorini f. & vaiani s. c. (2001) – benthic foraminifers and transgressive-regressive cycles in the late quaternary surface sediments of the po plain near ravenna (northern italy). boll. soc. paleont. ital., 40 (3), 357-403. orrù p. e., antonioli f., lambeck k. & verrubbi v. (2004) – holocene sea-level change in the cagliari coastal plain (southern sardinia, italy). quaternaria nova, 8, 193-212. sgarrella f. & moncharmont zei m. (1993) benthic foraminifera of the gulf of naples (italy): systematics and autoecology boll. soc. paleont. ital., 32 (2), 145-264. reille m. (1992) – pollen et spores d’europe et d’afrique du nord. laboratoire de botanique historique et palynologie, marseille, 544 pp. reille m. (1995) – pollen et spores d’europe et d’afrique du nord. laboratoire de botanique historique et palynologie, marseille, supplémet i, 332 pp. reille m. (1995) – pollen et spores d’europe et d’afrique du nord. laboratoire de botanique historique et palynologie, marseille, supplémet ii, 521 pp. reille m. (1999) – pollen et spores d’europe et d’afrique du nord. laboratoire de botanique historique et palynologie, marseille, 535 pp. climatic and environmental changes of the santa ... january 15, 2011 15 gennaio 2011 microsoft word 00_indice_lm04.docx il quaternario it issn 039-3356 italian journal of quaternary sciences 24 (1), 2011 67-74 jaminia (jaminia) malatestae esu, 1988 (mollusca, gastropoda, enidae) from the middle and late pleistocene of central-southern italy. palaeoecological implications carmine d’amico1 & daniela esu2 1dipartimento stat, università degli studi del molise, pesche (isernia) 2dipartimento di scienze della terra, sapienza università di roma sapienza, igag cnr, roma corresponding author: d. esu <daniela.esu@uniroma1.it> abstract: d’amico c. & esu d., jaminia (jaminia) malatestae esu, 1988 (mollusca, gastropoda, enidae) from the middle and late pleistocene of central-southern italy. palaeoecological implications. jaminia (jaminia) malatestae is a fossil land gastropod of the family enidae. the species described by esu (1988) was dedicated to the quaternarist geologist and palaeontologist alberto malatesta who recognized, at the base of the ponte galeria formation (rome), the “blue-grey helicella bearing clays”, stratum typicum of the species, dated to the early middle pleistocene. j. (j.) malatestae is an endemic species of central-southern italy ranging from the early middle pleistocene to the late pleistocene. it was recovered from deposits with oligotypical assemblages of terrestrial gastropods and small mammals of cold-arid climate. during the middle pleistocene the species occurred in lazio, at fontignano and san cosimato (ponte galeria and aurelia formations, rome) in an oligotypic molluscan assemblage of cold climate and reworked in a politypic assemblage of temperate-warm climate respectively, and in abruzzo, at case picconetto (pescara) in a palaeosol of an alluvial deposit, associated with non-marine mollusc species typical of open environments and cold climate. in the middle and/or late pleistocene the species occurred in marche, at gola della rossa (ancona) in a cave-fill deposit with oligotypic molluscs of mountain grassland, and at polesio (ascoli piceno) in a sandy layer interbedded to gravels of the last glacial period, associated with gastropods of open environment and cold climate. in the late pleistocene (last gacial period) the species occurred in campania with oligotypic molluscan assemblage of cold climate from a loess deposit at telese (calore river valley) and from a sandy layer interbedded to gravels at tufino (naples). both the structure of the molluscan assemblages and the autoecology of the accompanying species suggest that j. (j.) malatestae populated open-dry palaeoenvironments in the central-southern italian peninsula during cold climatic periods of the middle and late pleistocene. its record in non-marine quaternary deposits of italy is an useful tool to infer reliable palaeoenvironmental and palaeoclimatical information. riassunto: d’amico c. & esu d., jaminia (jaminia) malatestae esu, 1988 (mollusca, gastropoda, enidae) del pleistocene medio e superiore dell’italia centro-meridionale. implicazioni paleoecologiche. jaminia (jaminia) malatestae è una specie di gasteropode terrestre della famiglia enidae conosciuta solo allo stato fossile. la specie, descritta da esu nel 1988 su materiale fossile proveniente dalle “argille ad helicella” del pleistocene medio-inferiore affioranti a ponte galeria (roma), è stata dedicata dall’autrice ad alberto malatesta, paleontologo e geologo del quaternario, che per primo individuò le “argille ad helicella”, stratum typicum della specie, alla base della formazione di ponte galeria. la distribuzione cronostratigrafica di j. (j.) malatestae, che risulta essere una specie endemica dell’italia centro-meridionale, va dal pleistocene medio inferiore al pleistocene superiore. generalmente si rinviene in associazioni malacofaunistiche e a micromammiferi indicatrici di ambienti aperti e condizioni climatiche fredde ed aride. nel pleistocene medio è nota nel lazio, a ponte galeria e, frammentaria, nella formazione aurelia (roma) come elemento non autoctono di un’associazione a molluschi terrestri e dulcicoli di clima temperatocaldo, in abruzzo (case picconetto, pescara) in un paleosuolo di un deposito alluvionale (età ca 0.48 ma) associata a molluschi terrestri di ambiente aperto e clima freddo. nelle marche è nota a gola della rossa (fabriano, ancona) in un’ associazione oligotipica a molluschi terrestri di prateria montana in depositi di riempimento di una grotta riferiti al “riss” finale o “würm” iniziale, e a polesio (ascoli piceno), in un deposito sabbioso intercalato a conglomerati riferiti all’ultimo glaciale, associata a specie terrestri di ambiente aperto e clima freddo. in campania è stata rinvenuta in associazioni oligotipiche indicatrici di clima freddo-arido in un deposito di loess appartenente al “terrazzo inferiore” del fiume calore (benevento), attribuito al pleistocene superiore (“würm”), e in sabbie intercalate a ghiaie riferite allo stadio isotopico 2 nei pressi di tufino (napoli) (valle del torrente clanio-acqualonga). il carattere generalmente oligotipico delle associazioni in cui j. (j.) malatestae è presente e l’autoecologia delle singole specie che l’accompagnano suggeriscono che questa specie popolava i paleoambienti privi di vegetazione arborea e relativamente aridi nell’italia centro-meridionale durante le fasi climatiche fredde del pleistocene medio e superiore, e ne fanno un elemento utile per significative indicazioni paleoambientali e paleoclimatiche. key words: jaminia (jaminia) malatestae, enidae, palaeoecology, palaeoclimate, pleistocene, italy. parole-chiave: jaminia (jaminia) malatestae, enidae, paleoecologia, paleoclima, pleistocene, italia. 1. introduction the distribution and abundance of terrestrial molluscan species are controlled by a number of interacting factors (barker, 2001; pfenninger & posada, 2002; davies, 2008). among these both temperature and relative humidity constraining the physiology and life cycle of terrestrial molluscs influence the differing geographical distribution of the species. each species has a thermal interval controlling its own physiological functions c. d’amico & d. esu 68 and outside the ranges the species cannot survive (moine et al., 2002 and references therein). these authors demonstrated that the mean temperature of the coldest month and annual thermal magnitude are the most important forcing parameters for the distribution of modern as well as quaternary land mollusc species. modern terrestrial molluscs are indices both of vegetation type and climate, permitting them to be grouped in ecological classes (boycott, 1934). quaternary terrestrial molluscan assemblages are mainly constituted by extant species which do not show significative changes in their ecological requirements at least from the middle pleistocene (gliozzi et al., 1997; rousseau et al., 2007). they can be gathered in ecological groups, as well as the living species, and used to infer general variations of environmental conditions related to the climatic cyclicity of quaternary glacial and interglacial periods. among land molluscan assemblages, woodland and steppe/grassland communities provide the major useful data on climatic fluctuations, indicating respectively warm intervals characterized by woodland expansion, and cold phases with decreased arboreal covering (sparks, 1961; id, 1964; ložek, 1964; id, 2000). a large number of studies that utilized the ecological patterns of terrestrial molluscs to infer quaternary palaeoclimatic signatures was published in past decades (for example, ložek, 1964; rousseau & wu, 1999; rousseau et al., 2000; wu et al., 2000). land molluscan assemblages were intensively studied in quaternary loess deposits of central and eastern europe, as well as in north america and in china, where their palaeoecological framework and related palaeoclimatic attributes have been used as useful biostratigraphical tools (rousseau, 2001). in the italian peninsula, at the beginning of the middle pleistocene, consequently to a general renewal probably related to the onset of the 100 ka orbital cyclicity, the non-marine molluscan assemblages became quite modern (esu & girotti, 1991; gliozzi et al., 1997) and strongly influenced by climatic change: the politypic assemblages are related to temperate and temperate-warm climatic phase (interglacial), while the oligotypic ones occurred during cold oscillations (glacial) (esu et al., 1989). in this work we give an overview of the geographical (fig. 1) and stratigraphical distribution of the terrestrial fossil species jaminia (jaminia) malatestae esu based on literature data published over the last 30 years, and highlight its palaeoecological meaning. the palaeoecology of each molluscan assemblage in which the species was recorded is analyzed. furthermore we report the unpublished occurrence of j. (j.) malatestae in an upper pleistocene deposit of the marche region. 2. systematic remarks phylum mollusca cuvier, 1797 class gastropoda cuvier, 1797 order stylommatophora schmitt, 1855 family enidae woodward, 1903 genus jaminia risso, 1826 subgenus jaminia risso, 1826 jaminia (jaminia) malatestae esu, 1988 fig. 2 1980 chondrula (jaminia) reversalis conato et al., p. 143 (non bielz). 1988 jaminia (jaminia) malatestae esu, p. 228, fig. 1. 1989 chondrula reversalis esu et al., p. 288 (non bielz). 1991 jaminia (jaminia) malatestae esu & girotti, p. 144. 1992 jaminia (jaminia) malatestae kotsakis et al., p. 336. 1997 jaminia malatestai gliozzi et al., p. 378. 1998 jaminia malatestae di vito et al., p. 281, fig. 9c. 2003 jaminia malatestai marcolini et al., p. 548, fig. 3a. description (esu, 1988). shell cylindro-conical, sinistral, of moderate size (height 10÷11.5 mm, diameter 4÷4.5 mm, occasionally 5 mm), with 7-71/2 rather flatsided whorls. apex large. sutures weak, faintly slanting. shell surface with weak, irregular, growth-lines well visible at sem. shell rather thick continuing with the same thickness into the mouth-edge. peristome neither expanded nor reflected, with a characteristic sinuous outer profile. mouth oval, always furnished with only one blunt parietal tooth more or less developed; sometimes a weak lengthened swelling is present along the columellar side. mouth-edge continuous bearing a little callus across the outer parietal area, always present in the specimens with preserved parietal peristome. the type material of j. (j.) malatestae was collected from the “blue-grey helicella bearing clays” (early middle pleistocene) at fontignano (rome) (figs. 1 and 3). at first it was ascribed to the species “chondrula (jaminia) reversalis (bielz, 1853)” by conato et al. (1980), then esu (1988), after direct comparison with specimens of the bielz’s species from eastern european quaternary non-marine deposits, stored in the geological institute of hungary (magiar allami földtani intézet) at budapest, formally classified the fontignano fossil record as j. (j.) malatestae dedicating it to the fig. 1 geographical distribution of j. (j.) malatestae. a) fontignano and san cosimato (rome); b) case picconetto (pescara); c) gola della rossa (ancona); d) polesio (ascoli piceno); e) telese (calore river valley, benevento); f) tufino (naples). distribuzione geografica di j. (j.) malatestae. a) fontignano e san cosimato (roma); b) case picconetto (pescara); c) gola della rossa (ancona); d) polesio (ascoli piceno); e) telese (valle del fiume calore, benevento); f) tufino (napoli). jaminia (jaminia) malatestae esu, 1988 (mollusca, gastropoda, enidae) … 69 quaternarist geologist and palaeontologist alberto malatesta, who first described the “blue-grey helicella bearing clays” in conato et al. (1980). gliozzi et al. (1997) reported the species as j. malatestai. nevertheless, according to the art. 31.1.1 of the international code of zoological nomenclature (iczn) (international commission on zoological nomenclature, 1999), the correct specific name is j. (j.) malatestae as firstly reported by esu (1988). 3. stratigraphical distribution and ecological framework j. (j.) malatestae ranges from the base of the early middle pleistocene1 to the late pleistocene. it is endemic of the italian peninsula and is recorded from few localities of central and southern italy (fig. 1). as the fossil status of the species, its ecological requirements were inferred from the autoecology of similar extant species, such as the congeneric jaminia (j.) quadridens (müller) to which it is often associate, and from the characteristics of the accompanying species. generally j. (j.) malatestae occurs in quaternary molluscan assemblages indicating grassland dried environments and cold climatic conditions. below we give an overview of the j. (j.) malatestae occurrences, focusing on the composition and the ecological framework of each related molluscan assemblage, according to ložek’s (1964) ecological classification of the central and eastern european quaternary non-marine molluscs (tab. 1). 3.1 lazio 3.1.1 fontignano (rome) the oldest occurrence of j. (j.) malatestae is registered in the lowermost middle pleistocene at fontignano (rome), in the “blue-grey helicella bearing clays” (fig. 3), a lower member of the ponte galeria formation in which conato et al. (1980) distinguished eight members, from the bottom: 1) river pebble and cobble conglomerates, 2) blue-grey helicella bearing clays, 3) beach conglomerates and bright yellow a. islandica sands,4) pebble gravels and sands with frequent crosslaminations, 5) venerupis senescens clays, 6) aeolian salmon sands, 7) lacustrine and marshy deposits, 8) “tufi grigi inferiori” (earthy and pisolitic tuffs). this stratigraphical succession registers the transitions from nonmarine to fully marine and non-marine conditions. more recently milli (1997) utilized a sequence-stratigraphy approach in refining the stratigraphy of the pleisto cene/holocene deposits of the roman area, distinguishing two composite third-order sequences, the monte mario sequence (mms) (early pleistocene) and the ponte galeria sequence (pgs) (middle-late pleistocene/holocene). the “blue-grey helicella bearing clays”, falling in the matuyama reversed palaeomagnetic epoch (marra et al., 1998), correspond to a lowstand system tract of the lower fourth-order sequence (pg1) of the pgs; it formed the inner portion of a coastal-barrier depositional system, laterally associated to a braid delta of a fluvial system evolving in a coastal plain with lowsinuosity braided channels (milli & palombo, 2005). this environmental interpretation is consistent with the terrestrial oligotypical molluscan assemblage rec tab. 1 ecological classes (ložek, 1964) of the mollusc species associated with jaminia (j.) malatestae. gruppi ecologici (ložek, 1964) cui appartengono le specie di molluschi associate a jaminia (j.) malatestae. 1 head et al. (2008; see also ogg et al., 2008) proposed to correlate the early-middle pleistocene boundary with the matuyama-brunhes palaeomagnetic chron boundary (about 773 ka) (mis 19). at present this proposal is informally accepted by the subcommission on quaternary stratigraphy (sqs) of the international commission on stratigraphy (ics), as reported in the “global chronostratigraphical correlation table for the last 2.7 ma v. 2009” (http://www.quaternary.stratigraphy.org.uk/ charts/; gibbard & cohen, 2008). nevertheless, in the present work, according to milli & palombo (2005), we utilize the ancient boundary of early-middle pleistocene, at transition mis 25 to mis 24. c. d’amico & d. esu 70 fig. 3 a) the “blue-grey helicella bearing clays” at fontignano (stratum typicum of j. (j.) malatestae); b) beach conglomerates and bright yellow a. islandica sands (photo: daniela esu). a) “argille grigio-azzurre ad helicella” a fontignano (stratum typicum di j. (j.) malatestae); b) conglomerati di spiaggia e sabbie giallo vivo ad a. islandica (foto: daniela esu). orded in the “helicella clays” (tab. 2). granaria frumentum (draparnaud), helicella itala (linné), and very probably j. (j.) malatestae, belong to the ecologic group 4s, including species that live in dry grassland (tabs 1 and 2). pupilla muscorum (linné) (5o) lives in dry exposed places or grassland, vallonia pulchella (müller) (5o) prefers slightly humid open grounds, trochulus hispidus (linné) (7m) is a widespread mesic species. g. frumentum, p. muscorum and t. hispidus are species more or less frequent in the loess molluscan assemblages of central europe (ložek, 1964). the oligotypy and the dominance of the species referred to the group 4s (fig. 4) are indicative of a steppe environment and cold-dry climatic conditions (esu, 1988; kotsakis et al., 1992). this is also confirmed by the record in the same deposit of two species of boreal arvicolids (rodents) of eastern europe, prolagurus pannonicus (kormos) and predicrostonix sp., belonging to the steppe lemming and collared lemming respectively (kotsakis et al., 1992). both the characteristics of the faunal assemblage and the fact that the “blue-grey helicella bearing clays” fall in reversed palaeomagnetic epoch led kotsakis et al. (1992) to attribute the inset of the sedimentary cycle of the ponte galeria formation immediately after the coldest peak of marine isotope stage (mis) 22. nevertheless, marra et al. (1998) referred the base of the ponte galeria formation to mis 20-19. 3.1.2 san cosimato (rome) only one fragmentary specimen (the last whorl with mouth), very probably reworked, was collected from the diatomitic muds of the aurelia formation (conato et al., 1980; pg6 of milli, 1997), in a rich politypic molluscan assemblage of about forty land and freshwater species characteristic of temperate-warm climate (esu, 1988; esu & girotti, 1991). based on stratigraphic evidences, radiometric dating, and vertebrate fossil record the aurelia formation was dated to middle pleistocene (mis 8-10) and the mollusc-bearing diatomitic layers can be referred to mis 9 likelihood (conato et al., 1980; gliozzi et al., 1997; milli, 1997; milli & palombo, 2005). 3.2 abruzzo 3.2.1 case picconetto (pescara) marcolini et al. (2003) reported j. (j.) malatestae in a silty-clayey palaeosol of a sedimentary succession, fig. 4 palaeoecological features of the analyzed molluscan assemblages. the ecological classes (ec, see tab. 1) and their relative frequency are reported for each assemblage (tab. 2). the percentages of the ecological classes for gola della rossa and telese assemblages are not available. carattere paleoecologico delle associazioni malacologiche analizzate. sono riportate le classi ecologiche (ec, vedi tab. 1) e le relative frequenze per ciascuna associazione (tab. 2). le percentuali delle classi ecologiche per le associazioni di gola della rossa e telese non sono disponibili. jaminia (jaminia) malatestae esu, 1988 (mollusca, gastropoda, enidae) … 71 cropping out at case picconetto (pescara), interpreted as a distal part of an old alluvial fan deposit. the two palaeosols recorded in the succession, one of which, the uppermost, holding j. (j.) malatestae, are related to a local stasis in the alluvial fan accretion. a tephra layer dated 0.48 ± 0.04 ma (apatite fission track dating) lies above the palaeosol containing j. (j.) malatestae. the molluscan assemblage consists mainly of terrestrial taxa (tab. 2). only two freshwater species, gyraulus (armiger) crista (linné) and g. (g.) albus (müller), occur reaching less than 0.3% of the assemblage. the land species typical of open ground (5o) are dominant, followed by open dry grassland taxa (4s) (fig. 4). the mesic species (7m) are represented by a discrete number of specimens of vitrea contracta (westerlund). the strictly forest (1w) and hygrophilous taxa (8h) are very scarce, represented by sphyradium cf. s. doliolum (bruguière) and vertigo angustior jeffreys respectively, which, according to ložek (1964), are warm-climate species. the molluscs are associated to an oligotypical micromammal assemblage with dominant arvicolids, such as microtus cf. m. arvalis (pallas), m. (terricola) gr. savii (de selys longschamps), followed by murids, such as apodemus gr. sylvaticus-flavicollis, and insectivores (crocidura sp.), indicative of open environment and mediterranean-type climate (marcolini et al., 2003). together, molluscs and small mammals indicate open ground environment and cold, but not severe, climatic conditions. the radiometric dating, the results of chemical analysis carried out on the tephra layer, and the palaeoenvironmental indications suggested by molluscs and small mammals, led marcolini et al. (2003) to correlate the case picconetto succession with mis 14. 3.3 marche 3.3.1 gola della rossa (ancona) esu et al. (1990) recorded j. (j.) malatestae from a cave-fill deposit (grotta del vento, gola della rossa, ancona) in an oligotypical molluscan assemblage (tab. 2). candidula spadae (calcara) and clausilia (clausilia) rugosa pinii westerlund, prefer open woodland, but locally can live in open or semi-open habitats [2w(s)]. at present, they have apennine distribution being common in the high mountain zone (manganelli et al., 1995; cianfanelli, 2009. j. (j.) quadridens (4s), chondrina avenacea (bruguière) (4sf) and p. muscorum (5o) populate dry grassland or open grounds. small mammals and one reptile are associated with the land molluscs: sorex antinorii bonaparte, s. minutus linné, rhinolophus ferrumequinum (schreber), myotis dasycneme (boie), pliomys lenki cfr. relictus chaline, m. arvalis, chionomys nivalis (martins), apodemus cfr. sylvaticus (linné), and hierophis viridiflavus (lacépède) (revised by t. kotsakis). both molluscs and mammals indicate open and rather dry mountain palaeoenvironment, and cold climatic conditions. based on small mammals the cave-fill deposit of gola della rossa can be attributed to the late middle pleistocene (mis 6) or early late pleistocene (mis 4) (esu et al., 1990). 3.3.2 polesio (ascoli piceno) we report the unpublished occurrence of j. (j.) malatestae in upper pleistocene non-marine deposits at polesio (ascoli piceno). in a recent work buccolini et al. (2010) (see also gentili et al., 1998), analizing the geomorphological evolution of the last 20 ka in the high hill sector (6001100 m a.s.l.) of mt. ascensione area (southern marche), described upper pleistocene stratified slope deposits made up of alternating sandy and gravel layers. the type stratigraphic sequence, about 30 m thick, crops out at porchiano and polesio (fig. 5). in the sequence, several palaeosols 20-50 cm thick, located at different heights with respect to the bottom of the deposits, occur. buccolini et al. (2010) constrain chronologically these deposits with four 14c ams dating of charcoal fragments present in 4 palaeosols, two located 30 cm and 1 m above the bottom of the porchiano sequence, and two 3 m below the top of the polesio sequence. at porchiano the palaeosols are dated > 51000 yr bp and 41640 ± 1260 yr bp, respectively, at polesio 23230 ± 170 yr bp and 22680 ± 170 yr bp. in a sandy layer of the polesio sequence, close to the dated palaeosols, an oligotypical assemblage of land molluscs rich in specimens was recovered. it is constituted by dominating (about 43%) taxa of steppe c. d’amico & d. esu 72 fig. 5 upper pleistocene stratified slope deposits of the mt. ascensione area (southern marche). schematic type stratigraphic sequences: porchiano (a) and polesio (b); c) stratigraphic section at polesio (from buccolini et al., 2010). depositi stratificati di versante del pleistocene superiore nell'area del monte dell'ascensione (marche meridionali). sequenze stratigrafiche tipo: porchiano (a) e polesio (b); c) sezione stratigrafica presso polesio (da buccolini et al., 2010). environment (4s) (fig. 4) represented by pupilla triplicata (studer), truncatellina callicratis (scacchi), j. (j.) quadridens and j. (j.) malatestae (tab. 2), followed (about 29%) by open land species (group 5o). c. spadae, fairly abundant (about 24%), prefers open woodland, but locally can live in semi-open to open habitats. the ecological framework of the molluscan assemblage leads us to infer open palaeoenvironment and cold climatic conditions. 3.4 campania 3.4.1 calore river valley (benevento) malatesta (1959) reported the presence of a land molluscan assemblage in a loess layer interbed ded to tufitic and detrital fluvial deposits of a sedimentary succession located near the mineral source named ‘a uolla on the left side of the calore river (telese, benevento). at present, this deposits, related by the author to the “würm”, are no more cropping out. the molluscan assemblage is constituted only by four species, j. (j.) malatestae (4s), v. pulchella (5o), p. muscorum (5o) and helicella sp. (tab. 2), indicating open dry environment and cold climate (esu, 1988; esu & girotti, 1991). 3.4.2 tufino (naples) di vito et al. (1998) reported j. (j.) malatestae in the clanio-acqualonga valley (naples). non-marine deposits mainly constituted by carbonate gravels crop out in a quarry near tufino town. a sandy palaeosol, 80 cm thick, interbedded with gravels yielded a rich, but oligotypical land molluscan assemblage (tab. 2). the species of dry grassland environment (4s) dominate (fig. 4). cernuella neglecta (draparnaud) represented by more than 500 specimens, p. muscorum of dry exposed places and v. pulchella of more or less damp open habitats (5o) are well represented. the ecological requirements of the molluscan fauna indicate steppe environment and cold climatic conditions. the deposit containing the molluscs was referred to the last glacial period (mis 2). 4. conclusion so far j. (j.) malatestae was found only in the seven quaternary non-marine deposits of central and southern italy listed above, ranging from the early middle pleistocene to late pleistocene. in all the deposits j. (j.) malatestae is accompanied by the dominance of steppe species (4s) and open land species (5o) (tab. 2 and fig. 4), except at san cosimato where it was reworked. the strictly forest species (1w) and the hygrophilous ones (8h), represented only at case picconetto by sphyradium cf. s. doliolum and v. angustior respectively, are very scarce (tab 2 and fig. 4). at fontignano, case picconetto and gola della rossa, small mammals were recovered with the land molluscs. the ecological and climatic requirements of the mammal species confirm the palaeoenvironmental interpretation of open-dry habitats and cold climate inferred by the molluscs. the palaeoecological interpretation of the molluscan assemblages containing j. (j.) malatestae is in agreement with the chronological attribution of the related deposits, correlated with the middle and late pleistocene marine isotope stages mis 22, 14, 6 (or 4) and 2, which, except mis 14, correspond to major or minor glacial events occurred at global scale from the estabilishing of the 100 ka cyclicity, at about 900 ka bp (ehlers & gibbard, 2007) (fig. 6). acknowledgements many thanks are due to dr. g. cilla for the help in the field-research at polesio (marche), and g. manganelli and g. zanchetta for the useful advices. jaminia (jaminia) malatestae esu, 1988 (mollusca, gastropoda, enidae) … 73 fig. 6 relations among middle-late pleistocene glacial events, marine isotope stages and the occurrences of jaminia (j.) malatestae in middle-upper pleistocene non-marine deposits of central and southern italy. relazione tra eventi glaciali del pleistocene medio e superiore, stadi isotopici marini dell'ossigeno e presenza di jaminia (j.) malatestae nei depositi continentali medio e tardo pleistocenici dell'italia centro-meridionale. references barker g.m. 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(1961) the ecological interpretation of quaternary non-marine mollusca proc. linn. soc. lond., 172 (1959-1960), pp. 71-80. sparks o. (1964) non-marine mollusca and quaternary ecology j. anim. ecol., 33, pp. 87-98. wu n., rousseau d.d., & liu x. (2000) response of mollusk assemblages from luochuan loess section to orbital forcing since the last 250 ka chinese sci. bull., 45(17), pp. 1617-1622. ms. ricevuto il 3/06/2010 testo definitivo ricevuto il 14/08/2010 ms. received: june 3, 2010 final text received: august 14, 2010 imp.cattuto_gambini& il ruolo della geomorfologia nella tutela della torre pendente di vernazzano (umbria) carlo cattuto1, ermanno gambini 2 & lucilia gregori 3 1 dipartimento di scienze della terra università degli studi di perugia, cattuto@unipg.it; lucilia@unipg.it 2 dipartimento di filosofia linguistica e letterature università degli studi di perugia riassunto: c. cattuto, e. gambini & l. gregori, il ruolo della geomorfologia nella tutela della torre pendente di vernazzano (umbria). (it issn 0394-3356, 2007). lungo il versante a oriente del lago trasimeno, presso la confluenza di due torrenti (f.so tegone e t. rio), si trovano i ruderi di un castello medievale del quale è rimasta pressoché intatta soltanto la torre di guardia; a causa della sua vistosa inclinazione, questo possente elemento architettonico è noto come la torre pendente di vernazzano. gli insediamenti del castello (case, chiese, mura, ecc.) sono stati progressivamente raggiunti e portati alla distruzione dai fenomeni franosi che hanno accompagnato la profonda e rapida incisione del f.so tegone e del t. rio entro la potente pila di “arenarie del trasimeno”, affioranti nel territorio come strati e banchi di arenarie e di calcareniti caratterizzati da un elevato grado di fratturazione. la rapida evoluzione dei versanti ha ridotto il vasto piano fondale del castello ad un’esigua superficie, limitata da un’alta scarpata verticale, continuamente ridotta da crolli lungo tutto il suo bordo. anche la torre pendente è stata raggiunta dalla nicchia di distacco di un’ampia frana e la sua inclinazione deriva dallo scivolamento e dal collasso della fondazione entro la pila litoide, progressivamente disarticolata dai fenomeni franosi. come intervento di “primo soccorso”, per evitare il crollo rovinoso della torre, è stato realizzato un sistema di ancoraggio, mediante gabbia d’acciaio e tiranti, ma si dovrà intervenire anche sul piano fondale della torre pendente (ancora ignoto), sul drenaggio delle acque dall’intera superficie e sulla riduzione dell’erosione al piede del versante. abstract: c. cattuto, e. gambini & l. gregori, the role of geomorphology in the conservation of the leaning tower of vernazzano (umbria). (it issn 0394-3356, 2007). in the estern side of the trasimeno lake, near the confluence between tegone and rio streams, lie the ruins of a medieval castle of which only the guard tower remains almost intact. because of its visible inclination this mighty architectural feature is known as the leaning tower of vernazzano. the castle premises (houses, churches, walls, etc.) have been progressively affected and destroyed by the landslide processes associated with the deep and rapid erosion of the tegone and rio streams within the thick layer of “arenarie del trasimeno” sandstone, surfacing as highly fractured layers and beds of sandstone and calcarenites. the fast evolution of the slopes has reduced the large foundation plane of the castle to a small surface, delimited by a high vertical escarpment continuously reduced by rockfalls along its whole edge. on top of the above surface activity, deeper and more complex landslide processes are present which – together with the rotational displacements in the rock – have been affecting the nort-eastern part of the relief supporting the leaning tower. downstream of this structure, even though at a significant distance, lies a disordered pile of stones, eradicated trees, and layers and blocks of rock sloping down into the bed of the rio torrent. the movement of this aggregate doesn’t occur as a whole, but happens through rockfalls and landslides occurring at different moments and locations. this alternates with periods of comparative stability, to the point that a path leading to the tower lies over the pile, even though it often gets interrupted or dragged downstream. this landslide event appeared localized and ascribable to the stream erosion at the base of a detritic cone. the geomorphologic study of the area, instead, has shown that the landslide is the surface manifestation of deeper and more complex landslides that can be regarded as rotational displacements in rock. such displacements have eventually reached the foundation zone of the leaning tower, triggering planar sliding phenomena which led the tower to lose its verticality, leaning in the directions of the strata. as a first-aid measure to prevent the collapse of the tower, an anchorage system consisting of a steel cage and tie rods was deployed, but in the future it will be necessary to work on the (still unknown) foundation plane of the tower, on draining water from the entire surface and on reducing the erosion at the base of the slope. parole chiave: geoarcheologia, geomorfologia, reticolo idrografico, umbria, lago trasimeno. keywords: geoarcheology, geomorphology, hydrographic pattern, umbria region, trasimeno lake. il quaternario italian journal of quaternary sciences 19(2), 2006 233-240 introduzione circa 200 m a nw del piccolo centro abitato di vernazzano, in comune di tuoro sul trasimeno (pg), si trovano i resti di un antico castello tra i quali spicca un’alta torre vistosamente inclinata verso ne (fig. 1) e perciò comunemente indicata e nota come la “torre pendente” di vernazzano. l’area è stata studiata, dal punto di vista storico e geologico (cattuto c. & gambini e., 2002), ipotizzando le cause che hanno condotto alla distruzione del castello e alla progressiva perdita della verticalità della torre. sulla base di questi studi è stato realizzato un progetto per la messa in sicurezza di questa importante testimonianza del passato. condizioni geomorfologiche generali l’area d’interesse, ubicata lungo il versante a oriente del l. trasimeno, comprende parte del versante sudoccidentale del m. castiglione (fig. 2) ed è solcata 234 c. cattuto, e. gambini & l. gregori da due corsi d’acqua, il f.so tegone e il t. rio, che confluiscono nei pressi del vecchio centro abitato di vernazzano. la torre pendente si colloca a nord della confluenza tra i due corsi d’acqua (fig. 3), sopra un rilievo la cui sommità risulta “spianata”, poco sopra l’isoipsa dei 375 m, da fenomeni di dubbia interpretazione. e’ probabile che detta superficie sia riferita ad antichi fenomeni erosivi del ciclo fluviale della valle del trasimeno (cattuto c. et alii, 1992) e che quindi si identifichi, in larga misura, come terrazzo orografico, prodotto dalla tettonica e dal conseguente adattamento del reticolo idrografico locale (fig. 4). la stessa superficie, tuttavia, è stata modellata, almeno in parte, per esigenze agricole e per necessità di insediamento. la profonda incisione operata dal f.so tegone e dal t. rio ha provocato la rapida regressione dei loro versanti al punto che, attualmente, la superficie spianata sulla quale sorge la torre pendente è limitata da una netta scarpata praticamente verticale. particolarmente energica risulta l’erosione del t. rio che, nel tratto compreso tra i 300 e i 500 m s.l.m., sta ancora incidendo il “gradino”, corrispondente alla superficie spianata sulla quale era edificato il castello, prodotto da una faglia diretta (fig. 4). condizioni geologiche generali nell’area in questione affiorano le “arenarie del trasimeno”, arenarie quarzoso feldspatiche micacee alternate con argille e marne, considerate torbiditiche ad “affinità toscana” (boscherini a. et alii, 1982 ; damiani a.v. & pannuzi l, 1985), che si presentano in banchi di notevole potenza, assetto monoclinalico e immersione nordorientale. mentre lungo il versante sinistro del f.so tegone gli strati sono a reggipoggio, lungo il versante destro del t. rio, il generale andamento a franapoggio (fig. 5) è localmente modificato dalla presenza di pieghe a stretto raggio e, soprattutto, dalla sconnessione delle rocce provocata da movimenti franosi (fig. 6). spesso inoltre, si rileva un assetto decisamente caotico degli strati, mentre alcune faglie dirette di modesto rigetto dislocano il versante “gradonandolo” fin quasi al lago trasimeno. caratteristiche litologiche per comprendere l’evoluzione dei versanti del rilievo sul quale si trova la torre pendente, si ricorda che: le rocce in affioramento sono in prevalenza carbonatiche e fig. 1 la torre pendente di vernazzano in comune di tuoro sul trasimeno. the leaning tower of vernazzano in tuoro sul trasimeno. fig. 2 cartografia geologica schematica dell’area della torre pendente: 1. direzione/immersione degli strati, 2. faglia diretta di modesto rigetto, 3. depositi clastici di copertura (detrito di falda, colluvioni, alluvioni), 4. basamento litoide costituito dalle “arenarie del trasimeno” (oligocene superiore – burdigaliano medio). schematic geological map of the leaning tower area: 1. strike and dip of the strata, 2. normal fault, 3. clastic deposits (debris, colluvium and alluvial), 4. bedrock composed of “arenarie del trasimeno” (upper oligocene – middle burdigalian). affette da un elevato grado di fratturazione; infatti le arenarie, e ancor più le calcareniti la cui potenza nei banchi supera spesso il metro, in virtù della loro 235il ruolo della geomorfologia nella tutela ... durezza e fragilità, sono intensamente fratturate al punto che, a luoghi, il complesso litoide, almeno nell’area d’indagine, può essere assimilato ad un mezzo semicoerente e/o incoerente (fig. 6); i giunti di strato sono segnati dalla presenza di veli argillitici e da marne fogliettate che spesso costituiscono non solo una superficie di discontinuità, ma anche un piano di possibile e facile scivolamento. solo raramente, infatti, i giunti di strato sono interessati da ondulazioni e strutture sedimentarie (ripple marks, flute casts, ecc.) in grado di conferire loro “scabrezza” e, quindi, incremento della resistenza allo scorrimento; la presenza del lago trasimeno determina elevati valori annui dell’umidità relativa e questa, sui corpi litici molto fratturati e relativamente freddi, dà luogo a “precipitazioni occulte” in grado di incrementare l’infilfig. 3 schema geomorfologico dell’area della torre: 1. direzione/immersione strati, 2. frana, 3. scarpata, 4. deposito colluvio-alluvionale, 5. superficie spianata, 6. corso d’acqua, 7. sentiero, 8. manufatto. geomorphological scheme of the leaning tower area: 1. strike and dip of strata, 2. landslide, 3. escarpment, 4. colluvial and alluvial deposits, 5. flattened surface, 6. strema, 7. path, 8. artifact. fig. 4 schema morfoevolutivo del versante orientale del lago trasimeno e relazione con i processi erosivi dei corsi d’acqua che lo alimentano: 1. depositi colluvio-alluvionali, 2. bedrock marnoso arenaceo, a. faglie dirette di modesto rigetto intercettano il profilo dei corsi d’acqua incrementando i dislivelli locali, b. questo evento provoca il “ringiovanimento” del ciclo erosivo dei corsi d’acqua che, ancora oggi, incassano profondamente nel bedrock il loro alveo; a quote ricorrenti restano superfici spianate utilizzate per l’agricoltura e gli insediamenti. morphoevolutionary scheme of the eastern side of the trasimeno lake, and relation to the erosional processes driven by feeder streams: 1. colluvium and alluvial deposits, 2. bedrock (marls and sandstones), a. normal faults with small throw cross the path of water streams, increasing local height differences, b. this event causes the “rejuvenescence” of the erosional cycle of water streams which – still today – carve their channel deeply into the bedrock. at specific heights there are flattened surfaces used for agriculture and settlement. fig. 5 il colle sul quale si erge la torre pendente è limitato da un’alta e ripida scarpata che evidenzia gli strati e i banchi delle “arenarie del trasimeno”. the hill over which the leaning tower lies is limited by a tall and steep escarpment that highlights the strata of the “arenarie del trasimeno”. fig. 6 l’elevato grado di fratturazione delle rocce affioranti ne assimila il comportamento meccanico a quello delle rocce semicoerenti e incoerenti. the high degree of fracturing of surfacing rocks makes their mechanical behavior similat to that of semi-coherent and incohesive rocks. 236 trazione, lo stato di saturazione del terreno e finanche una moderata dissoluzione delle rocce carbonatiche; l’escursione termica diurna può essere molto alta e, frequentemente, durante l’inverno, il termometro oscilla sopra e sotto lo zero; in queste condizioni i fenomeni locali di gelo-disgelo diventano morfogeneticamente importanti; l’elevato grado di fratturazione delle rocce permette alle acque meteoriche di infiltrarsi profondamente entro la pila litoide e di esercitare locali, rapidi incrementi del carico idrostatico, in specie dove la presenza di livelli a bassa permeabilità allunga i tempi di corrivazione sotterranea creando accumuli idrici temporanei; durante o dopo piogge abbondanti, infatti, lungo i versanti del rilievo sul quale è posta la torre, è facile rilevare emergenze idriche un po’ ovunque mentre clasti e massi anche di notevoli dimensioni crollano a valle in grande quantità. i ruderi del castello e la torre pendente di vernazzano la superficie spianata indicata è ingombra di pietrame proveniente dalle macerie dei manufatti ivi costruiti; tra il materiale diruto emergono porzioni di muri ancora in posto, la base di una torre rotonda e, un po’ più distante, una piccola chiesa (fig. 7), probabilmente s. maria delle trosce. la torre pendente, a base rettangolare (m 5 x 5.5), ha un’altezza massima di m 20.95 alla sommità dello spigolo di sw e di m 20.42 a quella dello spigolo di ne verso il quale la torre ha raggiunto la massima inclinazione. nel perdere la verticalità, la parte sommitale della torre ha subito anche una evidente rotazione passando progressivamente dalla sezione rettangolare (angoli di 90°, ancora mantenuti alla base), ad una sezione rombica. la parte sommitale dello spigolo di ne, sottoposta a maggior tensione, si è “allentata” per aver superato i 90° e le pietre che componevano la muratura si sono distaccate, distanziate e infine sono crollate (fig. 8). oltre quelle indicate, non esistono altre misure esatte, anche se buattini a. (1846) ha fornito un’accurata descrizione della torre e misure sufficientemente attendibili. questo autore descrive anche la base della torre che oggi non è visibile, perché mascherata da macerie e, soprattutto, perché infossata nel terreno. il confronto tra le misure fornite dal buattini e quelle oggi rilevabili dimostra come, in 150 anni, la torre si sia : infossata nel terreno per almeno m 1.80 (il buattini colloca, a m 4.63 da terra, la porta di accesso alla torre, mentre oggi la stessa si trova a m 2.80), inclinata ulteriormente (il fuori piombo alla base della torre, misurato dal buattini in m 2.35, oggi è di m 3.88; pertanto, nel 1846, l’inclinazione della torre era di circa 7°, oggi è quasi il doppio (13° lungo il lato ovest). la distruzione del castello: idrografia e stabilità dei versanti in virtù delle caratteristiche meccaniche e del grado di fratturazione delle rocce, l’arretramento dei versanti si attua essenzialmente per fenomeni gravitativi; più spesso mediante crolli (rock fall) di massi e di pietrisco, ma sono riconoscibili anche fenomeni più complessi, compositi (wp/wli, 1993), come valanghe di detrito (debris avalanches) e scorrimenti rotazionali in roccia. al riguardo si segnala il sistema franoso che più direttamente minaccia la stabilità della torre e che è perfettamente visibile da chi percorra il sentiero che, dall’alveo del t. rio, si inerpica fino alla torre pendente. tale sentiero viene spesso spostato verso valle e parzialmente o completamente ostruito da corpi franosi diversi, sovrapposti e/o accostati, che si muovono in modo autonomo, in tempi diversi e senza apparenti rapporti di causa/effetto. fig. 7 il rudere della piccola chiesa di s. maria delle trosce. the remains of the small curch of st. mary of trosce. fig. 8 nel perdere la verticalità, la torre ha subito anche una vistosa rotazione al punto che la sua porzione sommitale, in origine a sezione rettangolare, si è progressivamente deformata diventando romboidale; dove l’angolo ha superato i 90° le pietre di costruzione si sono distaccate e poi sono crollate. on losing its verticalità, the tower underwent a visibile rotation, to the point that its top, originally rectangular, was progressively deformed, becoming rhomboidal. in places where the angle exceeded 90 degrees, the construction stones have detached and then have fallen down. c. cattuto, e. gambini & l. gregori 237 seguendo l’assetto degli strati e l’evoluzione dei fenomeni franosi che interessano il sentiero, si è ipotizzato che, sotto la spinta sia del carico litostatico che idrostatico, l’ammasso roccioso possa muoversi anche lungo piani di scivolamento debolmente inclinati contromonte, sia esistenti (ondulazioni degli strati) che di neoformazione. in pratica si tratta di scorrimenti rotazionali in roccia che, presso la superficie, con la progressiva diminuzione dei vincoli laterali, danno luogo a crolli e a locali colamenti. questo rapido allontanamento del materiale provoca una nuova depressione “a tergo” innescando altri fenomeni di tensione, movimento reciproco dei blocchi fratturati, ampliamento delle fratture e scivolamento planare delle rocce sovrastanti. frequentemente gli ammassi litici sono omogenei, mantengono pressoché indisturbata la stratificazione e sembrano in posto; si ritiene pertanto che questi corpi rocciosi, che emergono come schegge dalla massa litica ridotta in clasti, possano muoversi, episodicamente, lungo piani preferenziali di scivolamento, talora cambiando la direzione del movimento. più spesso tuttavia l’ammasso roccioso è completamente caotico e in esso si trovano massi e blocchi di roccia, pietrisco, terra e resti vegetali (arbusti e tronchi). la geometria di questo ammasso e il tipo di movimento sono riconducibili al “colamento”, tuttavia l’elevata pendenza dei vari piani di scivolamento lungo i quali si realizza il franamento lo identificano, più spesso, come “debris avalanche” (varnes d.j., 1978). già presso la base della torre sono visibili gradini e lesioni del terreno, assimilabili a nicchie di distacco che disarticolano la massa rocciosa tanto profondamente che ormai dalla torre all’alveo del t. rio il corpo franoso, almeno in superficie, può essere considerato unico (fig. 9). questo movimento franoso si è evoluto a causa della progressiva erosione retrogressiva dei versanti tutt’attorno al rilievo che sovrasta la confluenza t. rio/f.so tegone (fig. 9), portando un po’ alla volta al crollo delle strutture del castello ivi edificato. ancora oggi, lungo l’alveo dei due torrenti, tra il materiale che ne costituisce il carico solido, è facile rinvenire pietre squadrate che possono essere riferite a strutture murarie. dapprima i piani fondali devono aver subito fenomeni assimilabili a cedimenti differenziali (gli “sprofondamenti” di cui parla il buattini) a causa dello scivolamento planare degli strati sui quali poggiavano e, quindi, della rottura a comfig. 9 l’erosione in alveo e i processi gravitativi hanno provocato la distruzione del castello di vernazzano e l’inclinazione della torre: 1. la torre, probabilmente quella di “guardia” del castello di vernazzano, è stata edificata nel xiii secolo, 2. la profonda incisione operata dal f.so tegone e dal t. rio provoca la progressiva distruzione del castello e, già dal 600, sono segnalati i fenomeni franosi, ancora in atto, che porteranno la torre ad inclinarsi verso ne. nel 1846 l’inclinazione della torre aveva raggiunto i 7°, 3. situazione attuale. la torre è inclinata di ben 13° ed è profondamente lesionata. streams erosion and gravitative processes caused the destruction of the castle of vernazzano, and the inclination of the tower: 1. the tower, probably the guard tower of the castle of vernazzano, was built in the 13th century, 2. the deep incision effected by the tegone and rio rivers causes the progressive destruction of the castle. landslides, still going on, have been reported since 1600. they lead the tower to lean towards north-east. in 1846 the inclination of the tower had reached 7 degrees, 3. current status. the tower is inclined by as much as 13 degrees and is deeply damaged. il ruolo della geomorfologia nella tutela ... 238 pressione dell’appoggio fondale via via sempre meno contrastato dallo scorrimento rotazionale dell’ammasso roccioso; a seguito di questi movimenti, le strutture si sono inclinate verso valle, come la torre, seguendo il movimento della massa litica in questa direzione (o, più raramente, “contromonte”) e, infine, sono crollate, insieme con ampie porzioni di roccia, per mancanza di sostegno al piede 1. datazione del fenomeno franoso che interessa la torre attorno al 1250, quando fu edificato il castello, l’area fondale dava probabilmente le migliori garanzie di stabilità, in virtù del tipo di roccia affiorante e della situazione topografica locale (superficie spianata), ma proprio le condizioni geomorfologiche che fornivano alla costruzione una posizione dominante e inaccessibile, nel lungo tempo, l’hanno portata alla distruzione. e’ diffusa la credenza che il castello sia crollato a seguito dei terremoti ma, come rilevato da cattuto c. & gambini e. (2002), almeno la torre ha resistito abbastanza bene agli eventi sismici che, a più riprese, hanno interessato il territorio orientale del lago trasimeno; tra quelli più intensi (sup. int. vi della scala mercalli), baratta m. (1901) e postpischl d. (1985) segnalano quelli distruttivi di sansepolcro del 1345 (int. ix), di città di castello del 1389 (int. viii) e di sansepolcro e monterchi del 1414. che hanno raggiunto l’intensità ix della scala mercalli. tuttavia, storicamente, non viene segnalato alcun rapporto tra questi terremoti e la distruzione del castello, mentre si deve considerare che lo shock sismico può avere, ripetutamente, innescato e/o favorito i movimenti franosi, in specie quando il terreno si trovava in condizioni sature. non v’è dubbio quindi che i fenomeni di frana e di crollo conseguenti la profonda incisione operata dal t. rio 2 siano i veri responsabili della progressiva distruzione dell’area edificata. agli inizi del seicento sono infatti segnalati i primi fenomeni franosi, ma i più deleteri si sono manifestati in un periodo abbastanza breve, tra il 1750 e il 1775 e, a causa di questi, la torre si è infossata nel terreno. nello stesso periodo sono segnalati (gambini e., 1995) i più alti livelli idrici del lago trasimeno, ovviamente legati ai più abbondanti afflussi meteorici, gli stessi che potrebbero aver aggravato l’instabilità del territorio. e’ molto probabile quindi che l’elevato grado di fratturazione della roccia e soprattutto la mancanza di vincoli laterali (rimossi dal franamento) abbiano portato allo schiacciamento dell’appoggio fondale e al cedimento della torre 3. considerati i meccanismi di frana (tensione e lesionamento della roccia, ampliamento delle fratture con scorrimento della porzione a valle, parziale rottura a compressione della roccia in fondazione rapidamente sottoposta al carico della struttura e, infine, scivolamento della stessa verso valle), si ritiene che l’inclinazione della torre non si sia attuata gradualmente, ma procedendo a “scatti” corrispondenti ad eventi concomitanti (precipitazioni gravose, deflussi sotterranei elevati, shock sismici, ecc.). 1 anche dalla documentazione storica si ricava che, sulla spianata ove erano fondati i vari edifici, si sono manifestate lesioni sempre più ampie del terreno e “sprofondamenti” (cavità riconducibili probabilmente all’ampliamento delle fratture tra i blocchi calcarenitici in movimento relativo tra loro), entro cui franavano il pavimento delle abitazioni o intere porzioni murarie. questi eventi sono segnalati già nei primi decenni del 1400, tanto che nel 1455 viene restaurata la stessa torre, forse già danneggiata dai cedimenti che ne hanno preceduto l’inclinazione, mentre nel 1457 viene rifatta la rocca di vernazzano che, in alcune parti, “minacciava rovina” (pellini p., 1664). nei primi decenni del 1500 le mura del castrum risultano semidirute e la documentazione, fattasi più dettagliata dalle “relazioni” delle visite pastorali effettuate dai vescovi al castello di vernazzano e in particolare alla chiesa di s. michele arcangelo che sorgeva presso la torre, dimostrano che i fenomeni di cedimento e di lesionamento sono progressivi, seppure alternati con periodi di minore attività. infatti, nel 1626, nella relazione del vescovo de torres (archivio diocesi perugia, vol. xv), vengono segnalati i primi danni alle fondazioni della chiesa, successivamente, nel 1655, come si legge nella relazione della visita pastorale del vescovo monaldi (archivio diocesi perugia, vol. xx) si tenta di riparare la stessa chiesa con l’introduzione di terra entro i vuoti che si erano prodotti sotto le fondazioni, ma nel 1747, a seguito della visita del vescovo ferniani (archivio diocesi perugia, vol. xxvii) la stessa chiesa è dichiarata inagibile a causa di lesioni murarie e cedimenti del pavimento molto gravi e infine, nel 1763 il vescovo amadei (archivio diocesi perugia, vol. xxviii), dichiara impossibile qualsiasi opera di riparazione e decreta l’abbandono della struttura. curiosamente, anton maria garbi, un noto pittore locale, in un pregevole quadro del 1769 dipinge parte del castello ancora in piedi, così come la chiesa di s. michele arcangelo e la torre, in posizione praticamente verticale; ma secondo il buattini (1846), la chiesa di s. michele arcangelo venne chiusa al culto nel 1772 ”per lo spavento arrecato alle genti dalle pendenze della torre”. stando a questi documenti, pertanto, la torre sarebbe stata coinvolta nel movimento franoso nel brevissimo periodo di un triennio. 2 ovviamente non è nota la profondità del f.so tegone e del t. rio, rispetto al piano di posa delle strutture murarie edificate nel tredicesimo secolo; tuttavia è probabile che la posizione “dominante” del castello derivasse proprio dalla profonda incisone dei due torrenti, compresa almeno tra i 5 e i 10 m. attualmente il dislivello tra la base della torre e il t. rio è di circa 20 m, pertanto è probabile che, in circa sette secoli, l’erosione in alveo abbia raggiunto un tasso medio di 1.5 cm/anno. 3 pur in assenza di dati geotecnici puntuali è di misure esatte relative alla larghezza delle sue fondazioni, è interessante notare che la torre, con i suoi 20 m di altezza e con una base di m 5 per 5.5, progressivamente rastremata verso l’alto, raggiunge un volume fuori terra di poco superiore ai 500 mc; dal momento che il vuoto interno è di soli 30 (forse 40) mc, il volume complessivo ammonta a 460/470 mc. la roccia utilizzata per la sua costruzione, seppure con i vuoti delle connessure, può raggiungere un peso di volume di almeno 2.5 t/mc; pertanto il peso complessivo della torre potrebbe aggirarsi attorno alle 1.200 t corrispondenti, in fondazione e se questa fosse una superficie piana, ad almeno 4 kg/cm2. questo valore non è particolarmente elevato, ma la diversa risposta meccanica delle rocce in fondazione (argilliti, marne, arenarie e calcareniti), il loro elevato grado di fratturazione, la possibilità di locali fenomeni di dissoluzione e di variazione rapida del carico idrostatico, possono giustificare la locale, bassa resistenza alla compressione della roccia e, quindi, il cedimento differenziale delle strutture e il loro collasso non appena l’appoggio fondale viene rimosso. c. cattuto, e. gambini & l. gregori conclusioni e messa in sicurezza della torre lo studio geomorfologica del territorio ha permesso di legare, con rapporti di causa/effetto, fenomeni e situazioni che sembravano indipendenti, quali: l’inclinazione della torre, attribuita a cedimento differenziale del terreno fondale, l’ammasso di pietrame, alberi e strati di roccia accumulati, e in movimento come valanga di detrito, lungo il versante destro del t. rio, abbastanza lontano dalla torre, il continuo crollo di materiale roccioso dalle scarpate richiamato a valle dallo scalzamento al piede operato dall’erosione del t. rio. quello che sembrava un semplice fenomeno di scivolamento del materiale clastico, accumulato come cono detritico lungo il versante destro del t. rio, si è rivelato invece la manifestazione superficiale di un fenomeno franoso più profondo e complesso, in gran parte riconducibile a scorrimenti rotazionali in roccia in movimento retrogressivo che, almeno nella zona sommitale del rilievo, innescano fenomeni di scivolamento planare. la torre pendente, seppur lontana dalla valanga di detriti segnalata lungo il versante del t. rio, è stata interessata, in un primo tempo, dallo scivolamento planare delle rocce in fondazione 4 e si è inclinata; ora è molto vicina alla nicchia di distacco del più alto degli scorrimenti rotazionali profondi ed è quindi prossima al collasso totale. negli anni 2004/2005 il comune di tuoro ha realizzato l’ardito progetto di messa in sicurezza della torre elaborato dallo studio tecnico ing. o. zucchini di camucia. nell’area prossima al ciglio occidentale della superficie spianata è stato incassato un voluminoso blocco di calcestruzzo (circa 150 mc) al quale sono state ancorate 5 coppie di cavi d’acciaio che tirantano una struttura costituita da angolari d’acciaio disposti lungo i quattro spigoli della torre, per tutta la loro altezza (fig. 10). senza questo lavoro di “primo soccorso” la torre sarebbe già crollata. tuttavia il progetto deve essere completato con la realizzazione di altre opere tese a frenare l’erosione in alveo del t. rio (costruzione di briglie), a ridurre l’infiltrazione delle acque sul corpo di frana e sull’intera zona ove affiorano i ruderi del castello (opere di drenaggio), a bonificare, per quanto possibile, la frana stessa (infiltrazioni di resine e/o malta cementizia) e, infine, a mettere in luce quanto di archeologicamente interessante emergerà dagli scavi che verranno condotti, alla base della torre, per controllarne la tipologia e lo stato delle fondazioni. bibliografia baratta m. (1901) i terremoti d’italia. saggio di storia, geografia e bibliografia sismica italiana. bocca, torino. boscherini a., nocchi lucarelli m. & pialli g. (1982) geologia della riva etrusca del tevere tra le confluenze del t. niccone e del t. nese. rend. acc. sc. fis. e nat., soc. naz. di sc. e lett. in napoli, 48, 409-438. 239 4 durante lo scavo per la posa del blocco di calcestruzzo al quale ancorare la torre, a circa 3 m di profondità dal piano di campagna, è stato intercettato il probabile piano di scivolamento planare più direttamente responsabile dell’inclinazione della torre. e’ facilmente riconoscibile poiché si identifica come piano di stratificazione sopra al quale gli strati calcarenitici sono ridotti in blocchi distanziati da ampie fratture riempite con depositi eluviali mentre, sotto questo piano, la roccia è omogenea e si può seguire il profilo degli strati per tutta la loro estensione, dal momento che le fratture non sono mai beanti e molte sono cementate da calcite. fig. 10 per sostenere il peso della torre, contrastandone la caduta, è stata allestita una gabbia d’acciaio tirantata e ancorata ad un blocco di calcestruzzo. in order to support the weight of the tower, preventing its fall, a steel cage was built, anchored with tie rods to a block of concrete. il ruolo della geomorfologia nella tutela ... 240 buattini a. (1846) memoria sopra le pendenze della torre di vernazano. tipografia di v. santucci, perugia. cattuto c. & gambini e. (2002) la “torre pendente” del castello di vernazzano. arnaldo lombardi editore. cattuto c., cencetti c., gregori l. (1992) il pliopleitocene nell'area medio-alta del bacino del fiume tevere: possibile modello morfotettonico studi geolog. camerti vol. spec, (1992/1),103108. damiani a. v. & pannuzi l. (1985) unità litologiche nell’ambito degli “argilloscisti varicolore” fra il cortonese e l’eugubino e preliminari considerazioni paleogeografiche e stratigrafiche. boll. serv. geol. d’ it., 103, 241-276. gambini e. (1995) le oscillazioni di livello del lago trasimeno. quaderni museo pesca lago trasimeno, 2. pellini p. (1664) dell’historia di perugia. venezia postpischl d. (1985) catalogo dei terremoti italiani dall’anno 1000 al 1980. cnr – pf “geodinamica” n. 114, vol. 2 b. varnes d. j. (1978) slope movements. types and processes. in: schuster & krizek (eds) landslides: analysis and control spec. rep. 176. transp. res. board. national academy of sciences. washington, 11-33. wp/wli international geotechnical societes' unesco working party on world landslide inventory (1993) multilingual glossary for landslides. bitech, richmond, british columbia, 59 pp. ms. ricevuto il 20 febbraio 2006 testo definitivo ricevuto il 31 ottobre 2006 ms. received: february 20, 2006 final text received:october 31, 2006 c. cattuto, e. gambini & l. gregori sess 1_160211.pub il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 1. introduction coastal wetlands exist in a dynamic equilibrium between forces that lead to their establishment and maintenance and forces that lead to their deterioration (day j.w. et al., 1999). one of the most important processes currently affecting coastal wetlands is relative sea level rise (rslr). marshes survive rising water levels only if they are able to accrete at a rate sufficient to offset rslr (cahoon d. et al., 1995). in addition to longterm sea level variations, salt marsh evolution is influenced by short-term fluctuations, such as those caused by tides. in fact, during the flood events the accelerating sea level rise promotes a rapid increase not only in water depth, but also in deposition rate on the marsh platform; on the other hand, the expanding tidal prism can enhance erosion and an expansion of the channel network, reducing the marsh area (allen j.r.l.,1997). the present paper documents the evolution, in the last seventy years, of a natural salt marsh located in the venice lagoon (italy), and points out the role of sea level variations in influencing its modifications. the study was carried out through the joint analysis of several high resolution aerial photographs taken from 1938 to 2007 (which documented the tidal channel changes) and the 1938-2007 yearly time series of the rslr (including eustacy and natural and human-induced subsidence) measured at the venice tide gauge station (carbognin l. et al., 2009). 2. general characteristics of the study area the lagoon of venice, covering an area of about 550 km2, is the widest in italy and the most important survivor of a larger system of lagoons that characterized the north adriatic coast in roman times. in the whole basin, water circulation is mainly guaranteed by a semidiurnal tide, with a range of about 1.4 m, and by the bora and scirocco winds, from ne and se respectively, which trigger mixing and transport processes and locally create wind waves responsible for re-suspension of sediments in lagoon shallows (umgiesser g. et al., 2004). in addition, along the navigable channels wave motion is also induced by boat traffic, which causes local erosion. recent short-term evolution of a venice lagoon salt marsh (italy) federica rizzetto & luigi tosi istituto di scienze marine cnr, venice, italy corresponding author: f. rizzetto <federica.rizzetto@ve.ismar.cnr.it> abstract: rizzetto f. & tosi l., recent short-term evolution of a venice lagoon salt marsh (italy). (it issn 03493356, 2011) the recent geomorphological evolution of a venice lagoon salt marsh was identified through the analysis of high resolution aerial photographs taken from 1938 to 2007, and compared with the yearly time series of relative sea level rise (rslr) measured in venice in the same period. the investigations pointed out a significant retreat of the southern salt marsh margin and modifications of the marsh drainage network. in the last century, relative sea level variations, decrease of sediment input, and hydrodynamic processes were responsible for erosion in large portions of the venice lagoon tidal flats. in contrast with this general trend, the studied salt marsh was able to offset rslr. although this behavior reflected the system’s local response to many factors, relations between geomorphological modifications and sea level changes appeared clearly evident. riassunto: rizzetto f. & tosi l., evoluzione recente di una barena situata nella laguna di venezia (italia). (it issn 0349-3356, 2011) l’evoluzione geomorfologica recente di una barena situata nella laguna di venezia è stata studiata attraverso l’analisi di foto aeree ad alta risoluzione scattate dal 1938 al 2007 ed è stata poi confrontata con i valori annuali di sollevamento relativo del livello del mare (rslr) registrati a venezia nello stesso periodo. le indagini hanno evidenziato un significativo arretramento del margine meridionale della barena e modificazioni dei suoi ghebi. nell’ultimo secolo le oscillazioni del livello del mare, la diminuzione dell’apporto di sedimenti ed i processi idrodinamici hanno provocato erosione generalizzata nelle piani tidali della laguna di venezia. in contrasto con questa tendenza, la barena in esame è riuscita a contrastare il rslr. sebbene tale comportamento sia stato condizionato da molti fattori, è apparsa chiaramente evidente una stretta relazione tra le principali modificazioni morfologiche e le oscillazioni del livello marino. key words: salt marsh, tidal creeks, sea level, venice lagoon. parole chiave: barena, ghebi, livello marino, laguna di venezia  57 59 58 in the last century, erosion, scarce fluvial sediment supply, loss of material through the inlets, and rslr (enhanced by human-induced land subsidence) were responsible for the reduction and disappearance of a large portion of venice lagoon salt marshes, except for some located in the northern basin, which preserve their original characteristics and are locally growing (ciavola p. et al., 2002; cappucci s. et al., 2004). their survival mainly depends on the flooding water turbidity and on the presence of sea grass that reduces wave and tide actions and favors the entrapment of sediments and their deposition on the marsh surface (bellucci l.g. et al., 2007). one of these intertidal well preserved landform, i.e. the san felice salt marsh, was chosen as study area. it is located north of the lido inlet (fig. 1) at the confluence of two tidal channels, i.e. the gaggian and the san felice. it is crossed by a meandering-dendritic network of tidal blind-ended creeks, extending from the san felice channel to the north, which allow the distribution of water and suspended sediments on the marsh platform during tidal flow and their return to the surrounding lagoon during ebb tide. moreover, many ponds are present in the northern zone. the san felice salt marsh is composed of clayey sandy silt and is mainly colonized by halophytic species. its elevation ranges from 0.0 m to about 0.7 m a.s.l. and generally decreases from south to north; consequently, the northern part can be considered a marsh flat. the presence of the jetties at the lido inlet, built at the end of the 19th century, has greatly reduced and disturbed the sediment input from the sea to the marsh platform and enhanced high energy processes close to the inlet (day et al., 1999). 3. discussion in the last seventy years the investigated area suffered significant geomorphological modifications (fig. 2). as regards the southern salt marsh margin, close to the san felice channel, a general retreat, estimated up to about 38 m in the western sector and up to 24 m in the eastern one, occurred over the whole period. expansion of the tidal creek network was produced by tributary addition, mainly in correspondence of channel bends where the bottom shear stress arises, and headward erosion of the existing creeks, as the higher values of shear stress are registered in correspondence of the channel tips (pethick j.s., 1969; steel t.j. & pye k., 1997; feola a. et al., 2005). other channel modifications fig. 1, location of the study area. ubicazione dell'area studiata.  fig. 2, detail of the tidal creek modifications occurred from 1938 to 2007. dettaglio delle variazioni morfologiche dei ghebi verificatesi dal 1938 al 2007. f. rizzetto & l. tosi 59 ms. received: testo ricevuto il consisted of sinuosity changes, enlargement of some important creeks, meander migration, and variations of shape and distribution of pans. comparison between salt marsh evolution and rslr trend (fig. 3) over the whole period pointed out that sea level variations significantly influenced geomorphological changes. from 1938 to 1970 groundwater exploitation was responsible for high subsidence, which increased rslr rates. this process was particularly intense between 1950 and 1970 and determined a severe retreat of the salt marsh margin, increase of channel width, decrease of channel sinuosity, headward extension of creeks, and formation of new ones. after 1970 lower rslr rates were measured because the groundwater extraction was regulated. however, minor sea level fluctuations were identified: (a) between 1970 and 1990 rslr rates slowed down, (b) in the period 1990-2001 rslr grew again, (c) from 2001 and 2007 new steady conditions appeared. since 1970, margin shift was in agreement with rslr, showing retreat when rslr increased and stabilization when sea level was stable. on the other hand, modifications of the tidal creek network were only partially in agreement with rslr, showing planform morphological variations also during periods of quite steady sea level conditions. this behavior reflected the local response to many other factors, such as tides, sediment availability, vegetation growth and density, and wave action. however, results from this study pointed out that rslr alone was responsible for a large part of the geomorphological modifications occurred over the whole period. acknowledgements this study was performed within the framework of the vector (action 3 r.l. 5 cliven) and cnr-rstl n. 809 projects. part of aerial photographs is courtesy of the magistrato alle acque consorzio venezia nuova. references allen j.r.l. (1997) simulation models of salt-marsh morphodynamics: some implications for high-intertidal sediment couplets related to sea-level change. sediment. geol., 113 (3-4), 211-223. bellucci l.g., frignani m., cochran j.k., albertazzi s., zaggia l., cecconi g. & hopkins h. (2007) 210pb and 137cs as chronometers for salt marsh accretion in the venice lagoon e links to flooding frequency and climate change. j. environ. radioact., 97, 85-102, doi:10.1016/j.jenvrad.2007.03.005. cahoon d., reed d. & day j.w. (1995) estimating shallow subsidence in microtidal salt marshes of the southeastern united states: kaye and barghoorn revisited. mar. geol., 128, 1-9. cappucci s., amos c.l., hosoe t. & umgiesser g. (2004) slim: a numerical model to evaluate the factors controlling the evolution of intertidal mudflats in venice lagoon, italy. j. mar. syst., 51, 257-280. carbognin l., teatini p., tomasin a. & tosi l. (2009) global change and relative sea level rise at venice: what impact in term of flooding. clim. dyn., doi: 10.1007/s00382-009-0617-5. ciavola p., organo c., vintrò` l.l. & mitchell p.i. (2002) sedimentation processes on intertidal areas of the lagoon of venice: identification of occasional events (acqua alta) using radionuclides. j. coast. res., s.i. 36, 139-147. day j.w. jr., rybczyk j., scarton f., rismondo a., are d. & cecconi g. (1999) soil accretionary dynamics, sea-level rise and the survival of wetlands in venice lagoon: a field and modelling approach. estuar., coast. shelf sci., 49, 607-628. feola a., belluco e., d’alpaos a., lanzoni s., marani m. & rinaldo a. (2005) a geomorphic study of lagoonal landforms. water resour. res., 41, w06019, issn: 0043-1397, doi:10.1029/2004wr003811. pethick j.s. (1969) drainage in tidal marshes. in steers j.r. (ed.) the coastline of england and wales (third edition), cambridge university press, new york, 725-730. steel t.j. & pye k. (1997) the development of salt marsh tidal creek networks: evidence from the uk. in: proceedings of the canadian coastal conference, guelph, ontario, 267-280. umgiesser g., sclavo m., carniel s. & bergamasco a. (2004) exploring the bottom stress variability in the venice lagoon. j. mar. syst., 51, 161-178.  fig. 3, venice tide gauge data from 1938 to 2007. variazioni del livello marino misurate a venezia dal 1938 al 2007. recent short-term evolution of a venice ... january 14, 2011 14 gennaio 2011 base optical bleaching and dose-response behaviour of al and ti centers in quartz agnese rita zuccarello1, anna maria gueli1, carmelo monaco2, angelo occhipinti1, gloria maria ristuccia1, 2 giuseppe stella1 & sebastiano olindo troja1 1 laboratorio di datazione tramite luminescenza e di metodologie fisiche applicate ai beni culturali del dipartimento di fisica e astronomia, università di catania & infn catania, italy 2 dipartimento di scienze geologiche, università di catania, italy corresponding author: a.r. zuccarello <agnese.zuccarello@ct.infn.it> abstract: zuccarello a. r. et al., optical bleaching and dose-response behaviour of al and ti centers in quartz. (it issn 0394-3356, 2011). electron spin resonance (esr) is one of the most suitable methods for the dating of sedimentary events during the quaternary. however, in some cases, related to the specific samples under examination, esr signals need to be previously analysed for the correct application of the methodology. in this paper, a methodological study for esr dating of geological sediments, by means of aluminium (al) and titanium (ti) centers in quartz, was carried out. in this case, it is necessary to verify the optical bleaching process of esr centers and to study the behaviour of the corresponding signal intensity vs absorbed dose. the maximal bleaching percentage of these centers was evaluated exposing samples to the light from a solar simulator for different times. the results showed, on the one hand, that ti center is totally bleachable, while the al center is characterized by a hard to bleach component, whose evaluation is necessary to correct the esr equivalent dose. on the other hand, in the case of ti-center, the growth curve of esr signal intensity vs dose showed a trend that, for high values, presented strong deviations from that of sse (single saturation exponential), normally used for equivalent dose determination. riassunto: zuccarello a. r. et al., optical bleaching and dose-response behaviour of al and ti centers in quartz. (it issn 03943356, 2011). la risonanza di spin elettronico (esr) è uno dei metodi più adatti per la datazione di eventi sedimentari del quaternario. tuttavia, a seconda della tipologia di campione in esame, è necessaria un’attenta analisi dei segnali esr per la corretta applicazione della metodologia. il lavoro presentato in questa occasione riguarda uno studio metodologico per la datazione di sedimenti geologici da segnali esr dei centri alluminio (al) e titanio (ti) dei cristalli di quarzo. in questo ambito, è necessario verificare l’avvenuto processo di bleaching ottico dei suddetti centri e analizzare l’andamento dell’intensità dei relativi segnali in funzione della dose assorbita. la percentuale massima di bleaching ottico è stata valutata esponendo i campioni alla luce proveniente da un simulatore solare per tempi differenti. i risultati ottenuti hanno mostrato, da un parte, che il centro ti si svuota totalmente e in tempi relativamente veloci, a differenza del centro al caratterizzato da una componente hard to bleach, la cui valutazione si rende indispensabile per la correzione della dose equivalente esr. d’altra parte, nel caso del centro ti, la curva di crescita del segnale esr in funzione della dose ha evidenziato un andamento che, ad alte dosi, si discosta da quello descritto matematicamente dalla funzione sse (single saturation exponential), normalmente utilizzata per la determinazione della dose equivalente. keywords: sediments, dating, esr parole chiave: sedimenti, datazione, esr il quaternario italian journal of quaternary sciences 23(2), 2010 251-256 1 introduction since the first successful experiment performed by zavoisky (1945), electron spin resonance (esr) has been applied to many fields of chemistry, physics, biology and geology. the interest in archaeological and geological esr dating began after the pioneering work of ikeya (1975) on a stalactite from akiyoshi cave in japan. since then, it has been applied to many materials and further studies have been made to improve the method. the most important dating applications concern minerals which are precipitated or biogenically secreted, such as carbonates in speleothems, mollusc shells, corals, …, or hydroxyapatite in tooth enamel, as well as materials which were heated in the past, such as volcanic minerals, and optically bleached (signal resetting by light exposure) (ikeya, 1993). in this last field, esr dating has been widely used to date sediments using signals from quartz inclusions as it contains several paramagnetic centers (yokoyama et al., 1985; tanaka et al., 1997; voinchet et al., 2003; 2004; tissoux et al., 2007; 2008; rink et al., 2007). in this case, quartz is used as a dosimeter accumulating dose as a result of ionising radiation in the environment or inside the crystal. the assumption is that radiation-induced signals in quartz crystals are reduced or zeroed by daylight exposure during transportation and sedimentation, and then regrow during the burial of quartz in sediments due to exposure to natural radiation. the total absorbed dose (the equivalent dose de) is obtained by the additive dose method and converted to an esr age by assessing the annual dose rate (ikeya, 1993). esr shares with osl (optically stimulated luminescence), the most common dating method for sediments, both the object of the measurements, quartz crystals, and the mechanism for zeroing of the centers connected to sunlight exposure. nevertheless, esr dating has a larger time range with respect to osl (not more than some hundreds of thousands of years). rink et al. (2007) showed, in fact, that esr yields agreement with independent age control up to about 2.5 ma, extending the range dating of optically exposed quartz in sediments by a factor of about 5: this places it among the most suitable methods for the quaternary period. 252 a.r. zuccarello et al. however, for the optimal application of the technique, it is important to know the optical bleaching behaviour of the esr dating signals. the aluminium (al) and titanium (ti) related impurity defects are usually used to date quartz grains by esr method. they are measured at cryogenic temperatures (77 k), differing from other paramagnetic centers typical of materials cited above. bleaching experiments showed that al-center has two components, one bleachable and the other non-bleachable (yokoyama et al., 1985; laurent et al., 1998; voinchet et al., 2003; 2004; 2007). thus, the presence of this last component must be taken into account in order to determine the real total dose absorbed by samples since their burial after the bleaching process. similar experiments on ti-center have shown that it can be fully zeroed (tanaka et al., 1997; toyoda et al., 2000; rink et al., 2007; tissoux et al., 2007; gao et al., 2009). in the present work we used the ti-li center because the two other types of ti signals (ti-h and ti-na) were not detected above the background in samples under examination. in this report we tested the effect of the al nonbleachable component and, following the additive dose protocol, artificial gamma irradiations were made in order to verify the degree of the eventual correction and to analyse the trend of al and ti-li signals vs dose. 2 experimental 2.1 sample preparation and irradiation sedimentary quartz samples from marine terraces of the south of italy were used for the study. the samples preparation was carried out under controlled lighting with our laboratory standard protocol (adapted from wintle, 1997 and cited references; aitken, 1998) to provide a 100-200 µm quartz fraction. each sample was treated with 10% hcl for 1h to remove carbonates, 35% h2o2 for at least one day to remove organic material, followed by washing with distilled water and drying. sodium polytungstate was used to separate the quartz from the feldspars and other silicate minerals. then, samples were etched by 40% hf for 45 min to remove the outer part of the quartz grains that was affected by alpha irradiation and fluorides were eliminated using 10% hcl for 10 min. finally, quartz grains were rinsed with distilled water and dried. artificial irradiation was performed using a 60co calibrated source at the ente per le nuove tecnologie, l'energia e l'ambiente (casaccia, rome). additional doses up to 25000 gy were given. 2.2 bleaching experiments optical bleaching experiments were performed to evaluate the behaviour of the esr intensity under sunlight exposure. the quartz samples were divided into seven aliquots of about 100 mg. each aliquot was then put in a stainless steel dish, where grains were spread out as a thin layer on a surface of 2.5 cm in diameter. the dishes were placed on a copper plate with a water cooling system. quartz grains were bleached using a 150 w ozone free xenon lamp (66002 oriel solar simulator) for different exposure times. the air mass filters a.m.0+a.m.1 were used to simulate solar spectrum at ground level when the sun is directly overhead. the illuminance was about 105 lux and the samples were continuously exposed from 0 to 400 h. 2.3 esr measurements and de calculation esr measurements were carried out on a jeol fa-100 x-band spectrometer in a finger dewar cooled to 77 k by liquid nitrogen, using microwave power of 5 mw and modulation amplitude 0.16 mt. the al-center intensity (see 1 in fig. 1) was measured from the top of the first peak to the bottom of the last peak of the part of the main hyperfine structure (yokoyama et al., 1985), while the ti-li intensity (see 2 in fig. 1) was evaluated from the bottom of the peak at g = 1.913 to the baseline (toyoda et al., 2000). esr intensities were normalized by the aliquots weights. a single saturating exponential (sse) function was fitted to the experimental data points in order to get de value (apers et al., 1981): i(d) = is (1 e (d+de) / ds ) where i(d) is the measured esr signal intensity, d the laboratory added dose, is the esr saturation level and ds the characteristic saturating dose. de value was calculated by extrapolating the sse function to the zero ordinate, considering only the first steps of irradiation. for the al-center, this value is comprehensive of the residual dose dr due to a non-bleachable component, evaluable from the bleaching response to the solar simulator light. therefore, the corrected equivalent dose de is determined by subtracting dr from the total dose. for the ti-center the de value was obtained directly by additive dose method, assuming that complete optical bleaching of the associated esr signal has occurred in the sedimentation phase. 3 results and discussion all the samples analysed exhibit esr signals of al and ti-li centers, as shown in figure 1 where a typical spectrum of a natural sample is reported. figure 1 esr signals of al and ti-li centers observed at 77 k for natural quartz grains extracted from marine terrace sediments. segnali esr dei centri al e ti-li di quarzo estratto da terrazzi marini osservati a 77 k. bleaching experiments showed that esr intensity decreased with illumination time, even if with a different decay-rate for the two al and ti-li centers. an example of experimental ti-li intensity decay of natural samples is plotted in figure 2a. it can be observed that, in a time less than 200h, it is totally erased. for this reason, the equivalent dose de was calculated directly by the additive dose method applied to ti-li signal, without any subtraction of residual dose (fig. 2b). for the al-center, the intensity reduced and then reached a plateau representing the residual intensity linked to the non-bleachable component by sunlight exposure. in this case, the data were fitted (fig. 3 on the left) using the exponential function, proposed by walther and zilles (1994): y = ae(-bx) i0 , in which x is the exposure time to the sunlight, y is the measured esr intensity, a and b are the parameters of the fit and i0 the residual intensity. from this last value and from natural esr signal intensity inat, it is possible to calculate the maximal bleaching percentage that, using the formula inat i0 bl(%) = ––––––– x 100, was between 20% and 30% for inat samples analysed. for this reason, the equivalent dose evaluated from al center was corrected for the presence of the residual level equal to that obtained in the laboratory bleaching, following the procedure described in voinchet et al. (2004). in this way, only the bleachable component of the al-center was taken into account (fig. 3). from the point of view of optical bleaching experiments, it can be observed that the use of ti-li center could be more practical, above all when it and ti-h and ti-na signals (when observed) give concordant de values, as reported in toyoda et al. (2000). however, it is important to consider also the expected equivalent dose of samples under examination and assuring that the esr center used for its determination is not saturated. with this aim, we irradiated the samples up to 25000 gy and the results from esr measurements are reported in figure 4. in the case of the al center (fig. 4a), we observed a rising in the dose-response curve, suggesting the possibility to determine higher de than those here reported, as also suggested by rink et al. (2007). the different approach for ti-li center (fig. 4b) that already saturated for doses of some thousands of 253optical bleaching and dose-response ... figure 2 – example of optical response of the ti-li center to the solar simulator light exposure (a) and growth curve of the same signal vs dose (b). esempio di curva di decadimento del centro ti-li in funzione del tempo di esposizione alla luce proveniente dal simulatore solare (a) e curva di crescita dello stesso segnale in funzione della dose (b). figure 3 – example of optical response of the al-center to the solar simulator light exposure (on the left) and of growth curve of al intensity vs dose (on the right), together with the procedure described in voinchet et al. (2004) for the determination of the corrected de, calculated only from the bleachable component. esempio di andamento del segnale del centro al in funzione del tempo di esposizione alla luce proveniente dal simulatore solare (a sinistra) e di curva di crescita dello stesso in funzione della dose (a destra), nonché della procedura descritta in voinchet et al. (2004) per la determinazione della de corretta, calcolata solo dalla componente otticamente svuotabile. 2a) 2b) 254 gy, as also observed in tissoux et al. (2007). at this state, the trend of the experimental data allows the use of the lower first steps of irradiation as sse function does not fit them for the presence of a knee region not followed by saturation. 4 conclusions for the dating of sediments, it is very important to evaluate the optical bleaching behaviour of the signal being used for dating. the al and ti-li signals of samples from marine terrace sediments were observed and their response to sunlight exposure was investigated. this confirmed the need for using only the bleachable portion of al-center while no correction was necessary in the case of ti-li signal. on the other hand, the methodological study at doses up to 25000 gy led to some observations. in particular, al signal dose response-curve presented a trend well described by sse function, while for ti-li center further measurements and phenomenological models are necessary to better understand the behaviour of the experimental data. in fact, anomalous behaviours of the esr signals may influence the age determinations. acknowledgements we wish to thank nunzio giudice, nunzio guardone, mario mazzeo, antonio rapicavoli and vito sparti for technical assistance. references aitken m.j. (1998) an introduction to optical dating – oxford university press, oxford. apers d.j., debuyst r., de canniere p., dejehet f. & lombard e. (1981) a criticism of dating by electron paramagnetic resonance (esr) of the stalagmitic floors of the caune de l’arago at tautavel proc. absolute dating isotope anal. prehistory meth. limits, 553-550. gao l., yin g.m., liu c.r., bahain j.j., lin m. & li j.p. (2009) natural sunlight bleaching of the esr titanium center in quartz – radiat. meas., 44, 501504. ikeya m. (1975) dating a stalactite by electron paramagnetic resonance – nature, 255, 48-50. ikeya m. (1993) new applications of electron spin resonance: dating, dosimetry and microscopy – world scientific, singapore. laurent m., falguères c., bahain j.j., rousseau l. & van vliet lanoé b. (1998) esr dating of quartz extracted from quaternary and neogene sediments: method, potential and actual limits – quat. geochronol., 17, 1057-1062. rink w.j., bartoll j., schwarcz h.p., shane p. & baryosef o. (2007) testing the reliability of esr dating of optically exposed buried quartz – radiat. meas., 42, 1618-1626. tanaka t., hataya r., spooner n.a., questiaux d.g., saito y. & hashimoto t. (1997) dating of marine terrace sediments by esr, tl and osl methods and their applicabilities – quat. sci. rev., 16, 257264. tissoux h., falguères c., voinchet p., toyoda s., bahain j.j. & despriée j. (2007) potential use of ti center in esr dating of fluvial sediments – quat. geochronol., 2, 367-372. tissoux h., toyoda s., falguères c., voinchet p., takada m., bahain j.j. & despriée j. (2008) esr dating of sedimentary quartz from two pleistocene deposits using al and ti-centers – geochronometria, 30, 23-31. toyoda s., voinchet p., falguères c., dolo j.m. & laurent m. (2000) bleaching of esr signals by the sunlight: a laboratory experiment for establishing the esr dating of sediments – appl. radiat. isot., 52, 1357-1362. yokoyama y., falguères c. & quaegebeur j.p. (1985) esr dating of quartz from quaternary sediments: first attempt – nucl. tracks, 10, 921-928. figure 4 example of growth curve of esr intensity of al (a) and ti-li (b) signals for γ irradiated aliquots up to 25000 gy. esempio di curva di crescita dell’intensità dei segnali al (a) e ti-li (b) su aliquote irraggiate tramite sorgente gamma con valori di dose fino a 25000 gy. a.r. zuccarello et al. 4a) 4b) 255 voinchet p., falguères c., laurent m., toyoda s., bahain j.j. & dolo j.m. (2003) artificial optical bleaching of the aluminium center in quartz implications to esr dating of sediments – quat. sci. rev., 22, 1335-1338. voinchet p., bahain j.j., falguères c., laurent m., dolo j.m., despriée j., gageonnet r. & chaussé c. (2004) esr dating of quartz extracted from quaternary sediments: application to fluvial terraces systems of northern france – quaternaire, 15, 135-141. voinchet p., falguères c., tissoux h., bahain j.j., despriée j. & pirouelle f. (2007) esr dating of fluvial quartz: estimate of the minimal distance transport required for getting a mawimum optical bleaching – quat. geochronol., 2, 363-366. walther r. & zilles d. (1994) esr studies on bleached sedimentary quartz – quat. geochronol., 13, 611-614. wintle a.g. (1997) luminescence dating: laboratory procedures and protocols radiat. meas., 27, 769-817. zavoisky e. (1945) spin-magnetic resonance in paramagnetics – j. phys., 9, 245-249. ms. ricevuto il 22 giugno 2010 testo definitivo ricevuto il 29 ottobre 2010 ms. received: june 22, 2010 final text received: october 29, 2010 optical bleaching and dose-response ... imp.milella& sea level during 4th – 2nd century b.p. in egnazia (italy) from archaeological and hydrogeological data maurilio milella 1, cosimo pignatelli 1, mario donnaloia 2 & giuseppe mastronuzzi 3 1 phd school of geomorphology and environmental dynamic, university of bari 2 sismological observatory, university of bari 3 department of geology and geophisics, university of bari abstract: milella m., pignatelli c., donnaloia m. & mastronuzzi g., sea level during 4th–2nd century b.p. in egnazia (italy) from archaeological and hydrogeological data (it issn 0394-3356, 2007). this paper aims to estimate the mean sea level position during the 4th–2nd cent. b.c. along the adriatic coast of apulia using archaeological and geomorphological data from the archaeological site of egnazia. the detailed topographic survey of wells, cisterns and tombs reported from giornali di scavo permitted us to reconstruct the probable groundwater piezometric surface in that period. two different scenarios have been considered. the first one considers the active state of wells: we added the value of 35 cm to the elevation of the well–bottom required in order to take water by means of jars. furthermore, we subtracted the same value to the elevation of the tomb / cistern–bottom because these structures couldn’t come into contact with groundwater. the second one considers the non–activity of wells: the dating of the wells, based on their replenishment, performed on ceramic fragments, indicates the time they were abandoned and the consequent transformation into dump. in this way only the values of well–bottoms for reconstructing the piezometric surface trend are used. the piezometric surface trend corresponding to the two hypothesis was reconstructed with arcmap 8.3 gis software through kriging interpolating method. sea level during 4th–2nd cent. b.c. stands at least -1,2 m present sea level. riassunto: milella m., pignatelli c., donnaloia m. & mastronuzzi g., livello del mare nel iv–ii secolo a.c. da dati archeologici e idrogeologici nell’area di egnazia (italia) (it issn 0394-3356, 2007). sec. a.c. lungo la costa adriatica della puglia nei dintorni della città di egnazia sulla base della ricostruzione del probabile andamento della superficie piezometrica della falda idrica di quel periodo. per questo studio sono stati utilizzati: i – rilievo topografico di dettaglio dell’area di egnazia; ii – la profondità dei pozzi e delle cisterne desunte dai giornali di scavo. e’ stato ricostruito il possibile andamento della superficie piezometrica della falda idrica dell’epoca in relazione a due differenti ipotesi di lavoro. la prima considera lo stato di esercizio dei pozzi: alle quote dei fondo–pozzi è stato aggiunto il valore di 35 cm, necessario a garantire il prelievo dell’acqua tramite vasi, mentre alle quote del fondo–tombe e cisterne è stato sottratto lo stesso valore di 35 cm, supponendo che tali strutture non dovessero essere a contatto con acque di falda. la seconda ipotesi presuppone l’interruzione dell’esercizio dei pozzi: infatti la datazione dei pozzi basata sul loro riempimento, costituito soprattutto da frammenti ceramici, indica il momento del loro abbandono e la conseguente trasformazione in “discariche”. in tal modo, per la ricostruzione dell’andamento della superficie della falda sono stati considerati esclusivamente i valori dei fondo–pozzi. attraverso il software arcmap 8.3 gis è stato ricostruito, mediante il metodo di interpolazione del kriging, l’andamento delle superfici piezometriche corrispondenti alle due ipotesi. si è potuto così ipotizzare che la posizione del livello del mare nel iv–ii secolo a.c. fosse almeno 1,2 m al di sotto della sua posizione attuale. keywords: sea level, holocene, archaeology, hydrogeology, puglia, italy. parole chiave: livello del mare, olocene, archeologia, idrogeologia, puglia, italia il quaternario italian journal of quaternary sciences 19(2), 2006 253-260 introduction in the mediterranean basin, indications of sea level stands during historical times can be obtained from geomorphological, biological and archaeological sources. particularly, in microtidal areas geomorphological data provide a valid tool to indicate the biological mean sea level within a few centimetres (paskoff & sa n l a v i l l e, 1983; da l o n g e v i l l e, 1987; la b o r e l & laborel deguen, 1994; pirazzoli, 1996) but it is difficult to date them because of the frequent absence of biogenic encrustations useful for radiometric analyses (auriemma et al., 2004). archaeological sites are a source of valuable data for reconstructing sea level changes. here radiometric data can be compared and confirmed by the archaeological chronology (erol & pirazzoli, 1992; stiros & pirazzoli, 1995; antonioli & leoni, 1998; fleming & webb, 1986; mourhange et al., 2001, sivan et al., 2001; auriemma et al., 2005). in the past, along the apulia coast there was an extensive colonisation due to humans especially in the areas characterised by stability of the landscape and the availability of fresh water. in particular, in the archaeological site of egnazia, located along the adriatic coast of apulia (fig. 1), the more ancient human settlement goes back to bronze age (16th cent. b.c.). its coast location, like several apulian protostoric settlements, made maritime activities easier because the jagged coastal area is suitable for docking and sheltering vessels which carried wares from transadriatic areas (cremonesi, 1979; sciarra bardaro–andreassi, 1982; auriemma et al., 2005). recent studies permit us to guess the egnazia settlement originated in the acropoli: an antropic–made low hill which spreads seaward between two small inlets, reached out into the 254 m. milella et al. hinterland occupying the area where the later roman age houses were found (dell’aglio, 1982). the egnazia economy was based mainly on ship commerce between the two sides of the adriatic sea: in fact, the town was an important merchant harbour and the wares were transferred by a track road network to the inner centres of apulia and lucania by the way of the traiana road. so egnazia represented an important crossroad and meeting point of the several aged cultures (donvito, 1988). it is possible to divide the urban space into three bands quite parallel to coastline (diceglie, 1981a, tav. i–v): the first one, the closest to coastal area, is related to maritime spaces and comprise caves, some messapica tombs and the ancient harbour; the second one, is located between the first and the traiana road, including the acropoli and public, religious and administrative buildings; the last one, situated to the south of the traiana road, including all civil buildings. beyond this third band, about 600 m inward from traiana road, there is the western necropoli area, used from the half of 4th cent. b.c. up to 4th cent. a.d. (fig. 1). the guidelines at the base of this work was originated by the assumption of the existence of sea level and land indicators (a u r i e m m a et al ., 2004). archaeological sea level indicators, such as harbour structures, fishery and so on, permit us to recognise with good approximation past sea level stands (antonioli & leoni, 1998). land indicators such as tombs, cisterns etc. at present below sea level indicate a minimum altitude under which sea level stood. the investigated hypothesis is that wells, cisterns and tombs in the coastal archaeological area of egnatia are useful to reconstruct the piezometric surface and to put in relation the sea level with the functioning of the wells. thus, the aims of this paper is to verify the availability of this method along rocky coasts and to define the error limit of the sea level identifications. regional settings the apulia region represents the emerged part of the foreland domain of both the apenninic and dinaric orogens. the apulian foreland is slightly deformed and is affected by nw–se and ne–sw trending faults that subdivided it into five structural domains: gargano area, tavoliere basin, murge upland, taranto–brindisi plain and salento peninsula. the uplift rate of the southernmost adriatic part of apulia, based on generic stratigraphic and morphological evidence, ranges between 0,15 and 0,19 mm/yr in the area around bari and about -0,02 mm/yr along the coastal area near brindisi (bordoni & valensise, 1998; ferranti et al., 2006). the archaeological area of egnazia is located on the adriatic coast of apulia between monopoli and fasano. here, at the feet of the murge plateau (locally about 400 m high) the coastal landscape is characterized by a sequence of sub–horizontal surfaces sloping towards sea from an elevation of about 120 m. these surfaces should be produced by marine abrasion phases which occurred since the middle pleistocene as a consequence of the superimposition of regional uplift and the glacio–eustatic sea level changes. the monotony of this landscape is broken by a relict drainage network characterized by deep valleys, locally named gravine or lame, generally parallel to each other and perpendicular to coastline, that were shaped for sapping processes (mastronuzzi & sansò, 2002a). the gently sloping rocky coast is marked by the presence of little inlets which guest pocket beaches; the present sea level is shaping a poorly developed wave cut platform locally alternated to a discontinuos notch. the stratigraphy of the egnazia area is characterized at the base by the presence of the calcare di bari unit (cretaceous), recognizable by drilling only, that represents the local basement, marked by karstic profig. 1 egnazia town: the different urban spaces are evidenced with bold lines (from cinquepalmi & cocchiaro, 2000, mod., 4, fig. 3). città di egnazia: in rilievo sono evidenziati i differenti spazi urbani (da cinquepalmi & cocchiaro, 2000, modificata, 4, fig.3). cesses. biocalcareous sandstone related to the calcarenite di gravina unit (lower pleistocene) (d’alessandro & iannone, 1984) overlies in transgression the limestone and outcrops extensively along the cost. therefore, this lithological sequence is characterized by a high permeability, due to fractures and karst. it causes the lack of a fluvial network due to the rapid rainwater infiltration: this feeds a wide deep aquifer that rests on seawater intruded from the nearby coastal area and its interface follows ghyben–herzberg principle. at present, in the inner part of murge plateau the piezometric surface reaches a maximum altitude of about +200 m m.s.l. sloping about 0,2÷0,8 % towards the coastline (cotecchia, 1977). bibliographic and field data processing to reconstruct the piezometric surface and the probable mean sea level during the 4th–2nd cent. b.c. along the egnazia coastal area the following data were used: i – archaeological and hydrogeological bibliographic data; ii – new detailed topographic survey of the entire egnazia area and the depth of wells and cisterns (fig. 2) inferred by digging journals (giornali di scavo). the piezometric level of the egnazia coastal area was reconstructed by means of bibliographic data (tanzarella, 1998; maggiore et al., 1999; maggiore & pagliarulo, 2004). in 1997, the piezometric level in the archaeological park area was about +0,12 m present b.s.l. whereas it was at +2,5 m present b.s.l. about 5200 m landward (tanzarella, 1998). moreover, the bibliographic check allowed us to obtain data on the typology and the depth of the archaeological structures, wells and cisterns, used as indicators for this study. furthermore, the dating of the same indicators carried out by means of ceramic replenishment were taken on. wells and cisterns have a good distribution in the entire area of the ancient egnazia, inside the archaeological park area and outside, along the coast and inside the western necropoli. a well represents a vertical hole dug by humans (fig. 3) with a depth of about 30 ÷ 40 cm below piezometric surface useful for collecting water by jars (sivan et al., 2001). instead, cisterns were used only to keep rainwater and groundwater withdrawn through wells: so their bottoms did not reach the piezometric surface (cocchiaro, 1982; tagliente, 2005). during archaeological surveys, 70 structures for water supplies were localized (fig. 4): 52 inside the present archaeological park area and 18 along coastal area. unluckily, only 10 structures out of the first group and 8 structures out of the second one, in particular wells and cisterns to the south of the acropoli, show enough data from digging journals about their depth. in particular, wells located inside the archaeological park area surrounding traiana road, have a mean depth of about 3 m; while the ones situated near coastline have a mean depth of about 1,8 m. among the 10 structures of archaeological park 1 dates back to 9th cent. b.c., 4 to 4th cent. b.c., 2 to 3rd cent. b.c., 2 to 2nd cent. b.c. and 1 to 1st cent. a.d.; all the 8 structures of coastal area to the south of acropoli date back to 255sea level during 4th 2nd century b.p. ... fig. 2 detail of a cistern entrance in the archaeological park area (cinquepalmi & cocchiaro, 2000, 16, fig. 37). particolare dell’imboccatura di una cisterna nell’area del parco archeologico (da cinquepalmi & cocchiaro, 2000, 16, fig. 37). fig. 3 well scheme: in the vertical sections 4 cavity for each side, named “pedarole”, can be distinguished. in the lower part a vertical sub-rectangular cavity opens (from digging journals). schema di un pozzo: nelle sezioni verticali si possono distinguere 4 cavità per ciascun lato, chiamate “pedarole”. nella parte più bassa si apre una cavità subrettangolare (dai giornali di scavo). 256 2nd cent. b.c. (tagliente, 2005). only the structures dating back to 4th–2nd cent. b.c. have been considered for this study. detailed topographic survey was carried out by total station (teodolite “wild t2” with a geodimeter “aga 14a”); it let us get spatial coordinates related to gauss boaga system datum ed 50 (x, y and z) of all the wells, cisterns and tombs inside egnazia area and depth of all the tombs inside western necropoli. z–elevations were related to the present biological sea level (= b.s.l.) (laborel & laborel deguen, 1994) thanks to the presence of living concretions of lithophyllum lichenoides and dendropoma sp. along the coastal inlets near the acropoli; this occurrence allows us to evaluate in +/0,10 m the error bar of shown data. so, in the area of the archaeological park near traiana road the mean elevation of well heads is about +4,8 +/0,10 m present b.s.l., while along the coastline the mean elevation of well heads does not go over +1,5 +/0,10 m present b.s.l.. the spatial coordinates of all the surveyed points (wells, cisterns and tombs) elaborated using software (surfer 8 and arcmap 8.3 gis – kriging method) permit us to draw a map where topography and the piezometric surface of egnazia area are shown (figg. 4, 5). the piezometric surface was reconstructed according to two hypothesized scenario. the a scenario considers the active state of wells: we add the value of 35 cm to the elevation of the well–bottom required to take water by means of jars (sivan et al., 2001); on the contrary, we subtracted the same value to the elevation of the tomb and cistern bottom because these structures could not come into fig. 4 topography restitution of egnazia town, by means of surfer 8 software, with contour lines. ox : archaeological points; __: contour lines; _: coastline; ab: hydrogeological section track. ricostruzione, ottenuta con il software surfer 8, dell’andamento plano–altimetrico dell’area di egnazia mediante curve di livello. ox : punti archeologici; __: curve di livello; _: linea di costa; ab: traccia della sezione idrogeologica. fig. 5 piezometric surface restitution of egnazia town, by means of arcmap 8.3 gis software, for b scenario. ox : archaeological points; __: contour lines; _: coastline; ab: hydrogeological section track. ricostruzione, ottenuta con il software arcmap 8.3 gis, dell’andamento della superficie piezometrica nell’area di egnazia nel caso dello scenario b. ox : punti archeologici; __: curve di livello; _: linea di costa; ab: traccia della sezione idrogeologica. m. milella et al. 257 contact with groundwater. the use of this value allows us to obtain the best extrapolation of the piezometric surface trend so that its slope is coherent with the one of the uptodate groundwater. the b scenario considers the non–active state of wells: the dating of wells based on their replenishment, obtained by means of ceramic fragments, indicates the time they were abandoned and consequent transformation into dump. in this way only the values of well bottoms for reconstructing the piezometric surface trend were used (fig. 5). according to these hypothesis, either real hydrogeological sections or theoretical best–fitted on 2° degree equations extrapolations, were obtained (figg. 6a,b). discussion auriemma et al. (2004; 2005) reconstructed a curve of relative sea level changes in ancient time using geomorphological, archaeological and radiometric data. in particular, in the inlet north to the acropoli submerged piers in opus caementicium of the roman age are present. these structures and the building techniques indicate that sea level stands at about -2,5 m present b.s.l. during the 1st cent. b.c.. hydrogeological section, “a–b”, made up for both the work scenario reaches out about 800 m from the south limit of western necropoli to the present coastline in front of acropoli (fig. 4). some uncertainties derive from the historical and bibliographical sources: depth of wells and cisterns, taken from digging journals, have not been ascertained because of their replenishment and / or covering protection following the archaeological digging surveys. in particular, in the archaeological park, differences of depth have been recognized: the bottom of one cistern is about 0,5 m deeper than the bottom of very close coeval wells; bottoms of wells of coeval age, up to 30 m close, fig. 6a real hydrogeological section and theoretical best – fitted on 2° degree equation extrapolation for a scenario. the rectangle represents the present archaeological park area. 1 = past piezometric level; 2 = present piezometric level; 3 = past extrapolation level based on “y” 2° degree equation. sezione idrogeologica reale e relativa estrapolazione teorica ottenuta mediante equazione di 2° grado, nel caso dello scenario a. il rettangolo corrisponde all’area del parco archeologico. 1 = livello piezometrico passato; 2 = livello piezometrico presente; 3 = estrapolazione del livello piezometrico passato sulla base dell’equazione di 2° grado “y”. fig. 6b real hydrogeological section and theoretical best – fitted on 2° degree equation extrapolation for b scenario. the rectangle represents the present archaeological park area. 1 = past piezometric level; 2 = present piezometric level; 3 = past extrapolation level based on “y” 2° degree equation. sezione idrogeologica reale e relativa estrapolazione teorica ottenuta mediante equazione di 2° grado, nel caso dello scenario b. il rettangolo corrisponde all’area del parco archeologico. 1 = livello piezometrico passato; 2 = livello piezometrico presente; 3 = estrapolazione del livello piezometrico passato sulla base dell’equazione di 2° grado “y”. sea level during 4th 2nd century b.p. ... 258 show differences of depth of about 0,8÷1,0 m. to overcome this discrepancy the extrapolated piezometric level, for both scenarios, has been considered (curve 3 in figg. 6a,b). the scenario a (active state of wells) suggest a piezometric level between about +1,15 m present b.s.l. along traiana road and about -0,8 m present b.s.l. on coastline. the scenario b (non–active state of wells) indicate a piezometric level between +0,75 m present b.s.l. in the archaeological park and -1,2 m present b.s.l. along the coast (tab. 1). assuming the position of sea-level stand at -0,8 or at –1,2 m during 4th–2nd cent. b.c. in both scenario the piezometric level of +1,95 m past b.s.l. along traiana road results. this value is too high and incongruous for the topographic and hydrogeologic features of egnazia area (tab.1). in fact the archaeological park is located only 250 m landward and in the last 30 years the piezometric level went down about 15% due to human activity (polemico & dragone, 1999). since the climatic state during 4th–2nd cent. b.c., it was not very different in comparison with the present time (mastronuzzi & sansò, 2002b) the past piezometric level could not be much different in comparison with the present trend too. the present piezometric surface in the egnazia area has a mean slope of 0,048%: it is quite steady up to 5200 m landward. in the curve 3 of figg. 6a,b it is possible to detect two sketches characterized by different slope. sketch 1, from western necropoli to traiana road, has a mean slope of about 0,076% and 0,073%, respectively for a and b scenario. sketch 2, from traiana road to coastline, has a mean slope of about 0,77% and 0,76%, respectively for a and b scenario. only the values obtained for the sketch 1 can be compared with the present piezometric mean slope. using the mean slope of sketch 1 the values of +0,19 m and +0,18 m, respectively for a and b scenario, result: these values should be the piezometric level in the archaeological park referred to every stand of past sea level. the piezometric levels calculated and the present one of +0,12 m b.s.l. (tanzarella, 1998) can be brought into comparison. thereby, the piezometric surface during 4th–2nd cent. b.c. along traiana road had to stand necessarily about 1,6 m below the wells–bottom (tab. 2). the archaeological park is only 250 m far from the coastline: according to the present hydrogeological features the piezometric surface near traiana road did not have to overcome the elevation of about +0,2 m past sea level. mean elevation of the wells–bottom is about 1,6 m above this piezometric surface. consequently, the wells of this area could not operate during 4th–2nd cent. b.c., according to the b scenario. thus, the reconstruction of the piezometric surface allowed us to estimate that sea level during 4th–2nd cent. b.c. had to stand at least -1,2 m present b.s.l. (fig. 7). in any case, the available data and the results of archaeological park area coastline past piezometric present past piezometric level related to past piezometric surface piezometric surface related to cisterns related to related to surface present b.s.l. wells / tombs past sea present related to = past sea level bottom bottom level b.s.l. present b.s.l. position (+/0,10 m) a hypothesis: activity +0,35 m -0,35 m +1,95 m +1,15 m +0,12 m -0,8 m b hypothesis: non – activity 0 m -0,35 m +1,95 m +0,75 m +0,12 m -1,2 m sketch 1: a – 19 sketch 2: 19 – b archaeological park area present past piezometric past piezometric past piezometric surface mean surface mean present piezometric surface mean slope from slope from piezometric level slope along necropoli to@ traiana road to level calculated by ab section traiana road coastline sketch 1 slope a hypothesis: activity 0,048% 0,076% 0,77% +0,12 m +0,19 m b hypothesis: non – activity 0,048% 0,073% 0,76% +0,12 m +0,18 m tab. 1 comparison among extracted levels for past and recent piezometric surface along different areas of egnazia town. confronto tra i livelli ricavati per le superfici piezometriche passata e attuale in differenti zone della città di egnazia. tab. 2. comparison among extracted slopes and relative levels for present and past piezometric surface along different sketches of ab section in egnazia area. confronto tra i valori delle pendenze medie e dei relativi livelli ricavati per le superfici piezometriche presente e passata in corrispondeza di differenti tratti della sezione ab nell’area di egnazia. m. milella et al. elaboration indicate a relative sea level change lower than supposed by a u r i e m m a et al. (2004; 2005). unluckily, they do not permit us to recognize the eustatic and/or tectonic contribution although the entire area where egnazia is located, is considered by some authors in slow downlift (mastronuzzi & sansò, 2002a; lambeck et al., 2004). moreover, this reconstruction fits in well with some recent surveys that, in coastal areas, individuate the bottom of messapic tombs up to -1,1 m present b.s.l.. therefore taking into account that some eastern necropoli coastal tombs and egnazia roman harbour structures stay currently below the present b.s.l. (auriemma et al., 2004) it is unlikely that messapic people used to bury dead people at the seaside, where storms and spray could reach the tombs. conclusion the aim of this work was to estimate the relative position of the sea level during 4th–2nd cent. b.c. by means of archaeological data from egnazia. news and bibliographic data permit us to imagine the trend of the piezometric surface related to 4th–2nd cent. b.c.; two hydrogeological sections respectively based on two different scenarios have been implemented. according to the suggestions derived by sivan et al. (2004), the first one considers the active state of wells adding the value of 35 cm to the elevation of the well–bottom and subtracting the same value to the elevation of the tomb / cistern–bottom. the second one considers the state of abandoning of wells. data and discussion shown in these pages indicate that wells, cisterns and tombs dug in coastal areas could be used in the reconstruction of piezometric surface and related sea level with prudence. in fact, pottery remains inside do not indicate necessarily the age of their use but more probably their use as a dump. moreover, when using bibliographic data, their accuracy needs to be verified, in particular in the evaluation of deep values. as a consequence the error limit of this method on rocky coast should be bigger than the 0,10 m supposed in previous pages or the 0,10÷0,20 m supposed by sivan et al. (2001) for sandy coasts. in summary, the shown data and the reconstructions obtained indicate that: i – the wells were dug in times before the 4th–2nd cent. b.c.; ii – the wells were abandoned and filled at least at the beginning of the 4th century; iii – the piezometric level during the 4th–2nd cent. b.c. ran at about 1,6 m below the wells-bottom; iv – the sea level during the 4th–2nd cent. b.c. was at least -1.2 m present one. the discrepancy between this last data and that indicated by the presence of the submerged harbour structure is only apparent; in fact, the value -1,2 m is a limit lower than the sea could stand and it is heavily conditioned by the approximation of data registered and derived by digging journals. acknowledgements we would like to thank anonymous reviewers for constructive criticism and useful suggestions, dott. rossella pagliarulo from cnr – bari and dott. vittoria tagliente for the helpful discussions. this work was financially supported by national project archeomar by ministero dei beni e delle attività culturali (project leaders: dott. l. fozzati; dott. c. mocchegiani carparo; leader of puglia unit: g. mastronuzzi). this is an italian contribution to the igcp project n.495 – international geological correlation programme “quaternary land-ocean interactions: driving mechanisms and coastal responses ” dell’unesco – iugs (project leader: dr. anthony long, university of durham, uk). 259 fig. 7. : curve of sea level change during the last 3000 years in southern apulia reconstructed from auriemma et al. (2004) data; … : curve of sea level change during the last 3000 years according to the past piezometric surface in egnazia area. ▲ : sea level during 4th 2nd cent. b.p. deducted by piezometric level in archaeological elements (wells, cisterns and tombs). curva della variazione del livello del mare durante gli ultimi 3000 anni lungo la puglia meridionale ricostruita in base agli indicatori di auriemma et al. (2004); … : curva della variazione del livello del mare durante gli ultimi 3000 anni secondo la ricostruzione della superficie piezometrica del passato nell’area di egnazia. ▲ : livello del mare durate il vi ii sec. a.c. dedotto dalla superficie piezometrica ricavata dagli elementi archeologici (pozzi, cisterne e tombe). sea level during 4th 2nd century b.p. ... references andreassi g., cocchiaro a & maruca a. 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(2001) holocene sea-level changes along the mediterranean coast of israel, based on archaeological observations and numerical model. in: palaeogeography, palaeoclimatology, palaeoecology, 167, 101 – 117. stiros s. c. & pirazzoli p. a. (1995) paleoseismic studies in greece: a review. quaternary international, 25, 57 – 63. tagliente v. (2005) problemi di approvvigionamento idrico ad egnazia. tesi di specializzazione in archeologia e storia dell’arte romana, a.a. 2003/2004. tanzarella v. (1998) idrogeologia della fascia costiera adriatica compresa tra l’abitato di fasano (br) ed il mare. tesi di laurea in scienze geologiche, università degli studi di bari, a.a. 1997/1998. 260 ms. ricevuto il 20 febbraio 2006 testo definitivo ricevuto il 31 ottobre 2006 ms. received: february 20, 2006 final text received: october 31, 2006 m. milella et al. imp.balini gssp definiti in italia stato dell'arte per il triassico marco balini dipartimento di scienze della terra “ardito desio”, università degli studi di milano, via mangiagalli 34, 20133 milano. <marco.balini@unimi.it> abstract: m. balini, the gssp defined in italy. state of the art for the triassic. in the last 10 years the subcommission on triassic stratigraphy increased speed in the definition of the gssp of the triassic standard global chronostratigraphic scale. in 2001 the base of the induan has been defined in china and few years later in 2005 the base of the ladinian has been defined in italy. among the gssp candidate sections which are at the present under discussion there are two sections in italy with a great potential. prati di stuores/stuores wiesen (dolomites) has been finally selected by the task group as the only candidate for the base of the carnian stage and the final ballot is in progress. pizzo mondello (agrigento) is one of the two candidates for the definition of the base of the norian stage and a final decision is expected by 2009. the italian successions exposed in lagonegro and western sicily might also have some potential for the definition of the base of the rhaetian, but more work is necessary to come to a selection of a possible candidate section. parole chiave: trias, gssp, italia. keywords: trias, gssp, italy il quaternario italian journal of quaternary sciences 21(1a), 2008 11-16 la definizione della scala cronostratigrafica del triassico la definizione della scala cronostratigrafica standard globale (standard global chronostratigraphic scale: sgcs) per il sistema triassico è compito della subcommission on triassic stratigraphy (sts, international commission on stratigraphy). la sts, come tutte le altre sottocommissioni della ics, è composta da volontari, che servono in qualità di corresponding members, voting members, task group members, t.g. chairman, ed executives. il task group è un gruppo di lavoro su un problema specifico che viene costituito in modo aperto e gerarchicamente flessibile. all'atto della costituzione di un t.g. l'inserimento è aperto a tutti, anche ai non membri della sts, purchè sia chiaro l'interesse ed il potenziale contributo dei candidati. le relazioni con l'ics sono tenute formalmente dagli executives (chairman, vice-chairman e segretario), il chairman è inoltre di diritto membro votante della ics. la sts nel suo complesso è tenuta a rispettare le scadenze di lavoro imposte dall'ics, e che sono a loro volta legate ai rapporti annuali, ed alle sessioni plenarie dell'iugs. il mandato principale che hanno tutte le subcommission, tranne la issc, è quello di provvedere a proporre i gssp (global stratotype section and point) per le unità cronostratigrafiche di ordine pari o superiore al piano della standard global chronostratigraphic scale non ancora formalmente definite secondo i canoni della international stratigraphic guide (salvador, 1994). task groups attivi nella sts il sistema triassico è suddiviso in 7 piani, ma solo l'induano ed il ladinico sono definiti con un gssp ratificato. l'induano è definito sulla base della comparsa del conodonte hindeodus parvus nello strato 27c della sezione di meishan d (cina: yin et al., 2001). il ladinico è definito in italia, nella sezione di bagolino b, sulla base della comparsa dell'ammonoide eoprotrachyceras curionii (brack et al., 2005). i cinque piani per i quali non è ancora stato definito il gssp rappresentano un problema piuttosto grosso per la sgcs del triassico, su cui la subcommission investe gran parte della sua attività. sono attivi nella sts 5 task group, ognuno dei quali è incaricato di analizzare le migliori successioni in cui è documentato l'intervallo del limite di un piano specifico. i t.g. attivi sono i seguenti: induano/olenekiano, olenekiano/ anisico, ladinico/carnico, carnico/norico, norico/ retico. a questi t.g. si affianca un gruppo di lavoro dedicato alle suddivisioni del triassico non marino. infine alcuni membri della sts partecipano all'enorme gruppo di lavoro sul limite triassico/giurassico (più di cento membri), ma la gestione di questo grossissimo problema (7 sezioni potenzialmente candidate) spetta alla subcommission on jurassic stratigraphy. sezioni stratigrafiche ed eventi marker in discussione per le facies marine del triassico la biocrono12 m. balini stratigrafia a più alta risoluzione è basata sugli ammonoidi ed i conodonti, per cui è tra questi due gruppi che solitamente vengono ricercati gli eventi marker dei gssp. le specie di ammonoidi offrono in assoluto il maggiore potere di risoluzione, con specie che spesso hanno un range inferiore o uguale alla durata di una subzona, mentre le specie di conodonti hanno una distribuzione un pò più lunga, in generale superiore alla durata di una zona. i conodonti peraltro sono più frequenti degli ammonoidi nelle successioni sedimentarie, per cui spesso si definiscono gssp usando bioeventi a conodonti in quanto questi sono più uno strumento piu' pratico. le attività dei task group sono complesse, ed i processi di verifica e discussione delle successioni migliori richiedono molto tempo, variabile da 10 a 20 anni. le motivazioni sono numerose e varie, quali la scarsità di specialisti in tanti settori soprattutto paleontologici e biostratigrafici, la difficoltà di comporre gruppi di lavoro multidisciplinari, la scarsità dei finanziamenti. a queste si devono talvolta aggiungere (purtroppo) personalismi e nazionalismi. il fattore principale che condiziona i tempi delle approvazioni dei gssp, è rappresentato dal fatto che la sezione stratigrafica perfetta, che rispetti tutti i requisiti segnalati da salvador (1994), non esiste, perciò si devono analizzare sezioni “imperfette”, la cui valutazione presenta margini di divergenze. lo stato attuale delle discussioni nei vari task group della sts è illustrato in fig. 1. al momento tre task group sono arrivati alla votazione finale: induano/olenekiano, ladinico/carnico e olenekiano/ anisico. per gli altri t.g. il momento della votazione è prossimo, ma non imminente. vediamo anzitutto lo stato dell'arte per quei limiti che vengono o verranno definiti all'estero (olenekiano ed anisico) e poi esamineremo con maggior dettaglio le possibilità di gssp in italia. il dibattito sul limite induano/olenekiano da tre anni si è focalizzato su due sezioni stratigrafiche: mud nell'himalaya dell'india e chaohu in cina. il t.g. ha raggiunto ormai accordo sul marker event della base dell'olenekiano, che è la comparsa del conodonte neospathodus waageni, però esiste profonda discordia su quale delle due sezioni sia la migliore, tanto che si hanno due proposte di gssp contrapposte. attualmente (ottobre-novembre 2007) è in corso la seconda votazione da parte del t.g., necessaria dato che nella prima votazione nessuna delle due proposte ha raggiunto la maggioranza del 60% di consensi. il t.g. olenekiano/anisico si trova in una altro tipo di difficoltà, pur essendo attesa una votazione per la fine di quest'anno (2007). il t.g. ha individuato già nel 1999 la più completa sezione stratigrafica a desli çaira in romania. questa sezione è stata studiata da un team internazionale, che ha acquisito i dati relativi a conodonti, foraminiferi, magnetostratigrafia e variazione degli isotopi stabili. il t.g. ha già dibattuto sulla scelta del marker event, votando in favore della comparsa del conodonte neogondolella timorensis. con queste premesse ci si aspetterebbe una soluzione facile e rapida dei lavori, invece la definizione del gssp è bloccata da anni sulla difficoltà di conclusione dello studio degli ammonoidi, che rappresentano il gruppo chiave per calibrare l'isocronia della comparsa di n. timorensis. prospettive per gssp definiti in italia le successioni sedimentarie italiane hanno un grande significato per la formalizzazione del triassico superiore, che almeno in buona parte ha ottime possibilità di venire definito con gssp in italia. gssp del carnico la definizione della base del carnico, e quindi della serie triassico superiore, è alla fine della procedura di formalizzazione. il t.g. ladinico/carnico dopo circa 9 anni di lavoro è giunto alla conclusione della sua attività, ed è in corso la votazione finale (novembredicembre 2007) da parte dei membri. la votazione riguarda una sola proposta, ovvero il fad dell'ammonoide daxatina nel livello sw4 della sezione di prati di stuores/stuores wiesen (dolomiti, italia; fig. 2) (mietto et al., in press), per cui si può dire con ragionevole tranquillità, che il carnico verrà definito in italia. la proposta in votazione è sostanzialmente uguale a quella presentata nel 1999 (broglio loriga et al., 1999), ma questa continuità non vuol dire che il t.g. abbia svolto poca attività. al contrario nei 9 anni di lavoro, la necessità di verificare la correlabilità tra le sezioni migliori al mondo, ha costituito uno stimolo fondamentale per l'approfondimento della bioe cronostratigrafia integrata dell'intervallo del limite. le tre sezioni migliori al mondo (prati di stuores, dolomiti; spiti, himalaya e south canyon, nevada, usa) sono state studiate da team interdisciplinari, ed i risultati sezioni significative/candidate marker event decisione retico steinbergkogel (austria) conodonti (2 opzioni) 2009 superiore norico pizzo mondello (it.), black bear ridge (can.) conodonti (4 opzioni) 2008 carnico prati di stuores (italia) fad daxatina 2007 medio ladinico bagolino (italia) fad e. curionii 2005 anisico desli caira (ro.), west pingdinshan (cina) fad ng. timorensis 2007 inferiore olenekiano chaohu (cina), mud (india) fad ns. waageni 2007 induano meishan (cina) fad h. parvus 2001 fig. 1 stato dell'arte della definizione della scala cronostratigrafica standard del triassico. a parte i piani induano e ladinico, definiti con gssp, tutti gli altri piani del triassico sono ancora in via di definizione. state of the art in the definition of the standard chronostratigraphic scale of the triassic. only the induan and ladinian stages are provided by a gssp, while the gssp of the other stages are still in progress. t r ia s s ic o hanno incluso anche la revisione della scala cronostratigrafca nordamericana. le sezioni analizzate erano in una certa misura complementari e non alternative, come spesso capita nell'analisi di candidati gssp. prati di stuores ha un buon record ad ammonoidi, cui si aggiungono gruppi minori, ed un segnale paleomagnetico primario. elementi negativi sono l'influenza paleoambientale sul record a conodonti che probabilmente spiega l'assenza di daonelle ed halobie. spiti ha un ricco record a bivalvi pelagici ed a conodonti, ma presenta una documentazione ad ammonoidi piuttosto limitata, inoltre è rimagnetizzata. in ultimo south canyon presenta sicuramente la migliore documentazione ad ammonoidi e un buon record a bivalvi pelagici, cui si accompagnano purtroppo un'esposizione scadente ed un record a conodonti limitato a una parte della successione, peraltro rimagnetizzata. i punti principali che sono stati approfonditi negli ultimi anni sono la posizione stratigrafica relativa degli ammonoidi frankites, daxatina e trachyceras, che nel 1999 non sembrava corrispondere tra il nord america e le sezioni tetidiane di prati di stuores e spiti, e la posizione del fad del conodonte paragondolella polygnathiformis, che per lungo tempo è stato un possibile candidato marker per la base del carnico, ma che sembrava avere posizioni molto diverse nelle diverse aree paleogeografiche. la scelta finale è stata indirettamente influenzata dagli specialisti di conodonti, che hanno abbandonato il sostegno del fad di p. polygnathiformis come possibile marker event della base del carnico, per cui questo evento è stato ridimensionato ad proxy del limite, insieme alla comparsa di halobiidae primitive. nel complesso la definizione del gssp del carnico rappresenta un successo per l'italia e per la ricerca italiana. le attività svolte dal t.g. ladinico/carnico hanno visto sempre i ricercatori italiani in primo piano. la direzione del t.g. è stata effettuata da m. gaetani (milano), con la collaborazione dello scrivente nel corso dell'ultimo anno. le sezioni stratigrafiche analizzate dal t.g. sono tre (prati di stuores, spiti e south canyon) e sono state studiate tutte da team condotti da italiani. le fondamentali ricerche a prati di stuores sono state coordinate prima da c. broglio loriga (ferrara), poi da p. mietto (padova), ed hanno visto come protagonisti numerosi ricercatori di padova, ferrara, perugia modena e milano. lo scrivente ha coordinato le ricerche sia in in spiti (himalaya, india) con a nicora (milano) e specialisti austriaci ed indiani, che a south canyon (nevada, usa), in collaborazione con specialisti americani e canadesi. gssp del norico al momento attuale (autunno 2007), il t.g. carnico/norico è arrivato a selezionare due successioni di per la definizione del gssp del norico: black bear ridge in british columbia (canada) e pizzo mondello nella sicilia occidentale (agrigento). 13gssp definiti in italia. stato dell’arte... la sezione di black bear ridge (orchard et al. 2001) è esposta lungo la riva del bacino artificiale del lago williston, nella parte nord occidentale della british columbia. la sezione è stata studiata da un gruppo molto ben organizzato di specialisti canadesi ed americani, in gran parte facenti capo al geological survey of canada. la successione ha un record a conodonti molto ricco ed una documentazione a bivalvi molto buona. gli ammonoidi sono abbastanza rari e non ben conservati, tuttavia permettono di riconoscere le ultime due cronozone del carnico e la prima del norico. elementi aggiuntivi sono i brachiopodi, e forse le variazioni degli isotopi stabili, mentre non ci sono dati di radiolari, e la magnetostratigrafia non è applicabile in quanto la successione è rimagnetizzata. la sezione di pizzo mondello (monti sicani, sicilia occidentale) presenta numerosi elementi di grande interesse. anzitutto la successione affiorante in questo sito sono i calcari con selce (equivalente alla formazione di scillato), che raggiungono uno spessore di circa 400m. la sezione è molto bene affiorante (fig. 3), essendo sviluppata in una cava attiva negli anni '70, e l'esposizione consente di seguire lateralmente gli strati anche per 100-200 metri. la facies è pelagica-emipelagica, con una costanza e regolarità veramente inusuale per un intervallo di tempo così lungo (carnico superiore-retico basale). la sezione è stata presentata a livello internazionale a metà degli anni '90 (bellanca et al., 1995, gullo, 1996; muttoni et al., 2001; 2004), ed è diventata un riferimento importantissimo per il record magnetostratigrafico e le variazioni del δ18o e δ13c, tuttavia presenta anche delle grossissime potenzialità biocronostratigrafiche (fig. 4). i calcari con selce del bacino sicano, sono noti dal xix secolo (gemmellaro, 1882 e 1904) per il ricco contenuto in ammonoidi e halobie, inoltre la facies è molto interessante per i radiolari. per valorizzare queste grosse potenzialità biocronostratigrafiche ed arrivare ad un proposta formale di gssp per pizzo mondello, si è recentemente costituito un ampio gruppo di lavoro composto da specialisti italiani (università di milano, ferrara, padova, palermo e fig. 2 la sezione di prati di stuores/stuores wiesen. the prati di stuores/stuores wiesen section. perugia) e stranieri (mit e cortland, usa; lausanne, svizzera). i primi dati disponibili sono stati presentati al congresso “the global triassic” di albuquerque (guaiumi et al., 2007) e sono in stampa (nicora et al., in press). i nuovi risultati hanno riscosso un notevole interesse tanto che il t.g. carnico/norico ha dilazionato la votazione sul candidato gssp al 2008, per poter tener conto degli studi in corso a pizzo mondello. nel corso del 2008 il team multidisciplinare che lavora a pizzo mondello programma di selezionare un bioevento a conodonti da presentare come candidato gssp, con il sostegno di biocronostratigrafia ad ammonoidi, halobiidae, radiolari, dinoflagellate, magnetostratigrafia, ciclostratigrafia, variazioni degli isotopi stabili e, probabilmente, datazioni radioisotopiche di tufiti. le speranze di una selezione in italia sono quindi ben fondate. gssp del retico il retico pressoché da sempre è il piano del triassico più difficile e discusso. in italia le successioni norico-retiche sono potenti e diffuse, ed è possibile che il nostro paese possa fornire spunti importanti anche per la soluzione del problema del limite norico/retico. al momento attuale il dibattito sulla definizione della base del retico è poco sviluppato, tuttavia nel 2007 è stata delineata una proposta di gssp (krystyn et al., 2007), sulla sezione di steinberkogel in alpi settentrionali (austria). questa sezione, ubicata nella regione storicamente importante di hallstatt, è molto interessante per la presenza di ammonoidi, conodonti e bivalvi, per la buona qualità del segnale paleomagnetico e le variazioni degli isotopi stabili, però è spessa solo 4 metri e quindi molto probabilmente condensata. il marker event non è ancora stato selezionato ma secondo krystyn va individuato con i conodonti. il team multidisciplinare che lavora a pizzo mondello sul limite carnico/norico sta valutando anche la possibilità di presentare una proposta di gssp per il retico. le sezioni/aree che si stanno esaminando sono pizzo mondello, lagonegro e le alpi orientali. in queste successioni, come a steinberkogel, si lavora principalmente sui conodonti. le sezioni in studio sembrano essere purtroppo un po' carenti per quanto riguarda ammonoidi e bivalvi pelagici, ma ci sono ottime potenzialità per quanto riguarda magnetostratigrafia e variazioni degli isotopi stabili. le indagini programmate per il 2008 sarenno determinanti per chiarire se esistono realmente elementi per una proposta di gssp in italia anche per il retico. bibliografia b ellanca a., d i s tefano p. & n eri r. 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(2005) the global boundary stratotype section and point (gssp) of the ladinian stage (middle triassic) at bagolino (southern alps, northern italy) and its implication for the triassic time scale. episodes, 28, 233-244. broglio loriga c., cirilli s., de zanche v., di bari d., gianolla p., laghi g.f., lowrie w., manfrin s., mastandrea a., mietto p., muttoni g., neri c., posenato r., reichichi m., rettori r. & 14 fig. 3 i “calcari con selce” affioranti a pizzo mondello in località la cava. la sezione è misurata in due segmenti (a e b) perfettamente correlati lungo strato. l'intervallo critico per la definizione del limite carnico/norico corrisponde alla parte media del segmento b. the “calcari con selce” exposed at pizzo mondello (la cava site). the section is composed of two segments (a and b) overlapping in part and very well correlated following bed along strike. the carnian/norian boundary interval is recorded in the middle part of segment b. m. balini 15 -9 0 9 00 vgp lat it ude ( °) 0 2 4 δ1 3 c ( per mil)δ1 8 o ( per mil) -4 -2 0 2 pm1 pm2 pm3 pm4 n pm5 n pm6 pm7 pm8 pm9 pm1 0 pm1 1 pm1 2 pizzo mondello ( mut t oni et al., 2 0 0 4 ) magnet ic polarit y pm4 r pm5 r in t e r v a l o f in t e r e s t in t h is p a p e r fig. 4 la sezione di pizzo mondello con magnetostratigrafia e variazioni degli isotopi stabili (da nicora et al., in press, modificato da muttoni et al. 2004). the pizzo mondello section showing magnetostratigraphy and variation of the stable isotopes (from nicora et al., in press, partly modified from muttoni et al. 2004). gssp definiti in italia. stato dell’arte... roghi g. 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(2001) fossil succession and sequence stratigraphy of the upper triassic of black bear ridge, northeast british columbia, a gssp prospect for the carnian-norian boundary. albertiana, 25, 10-22. yin h., zhang k., tong j., jang z.& wu s. (2001) the global stratotype section and point (gssp) of the permian-triassic boundary. episodes, 24, 102-114. salvador a. (ed.) (1994) international stratigraphic guide. second edition. v. di 214 pp. geol. soc. of america. ms. ricevuto il 2 aprile 2008 testo definitivo ricevuto il 17 aprile 2008 ms. received: april 2, 2008 final text received: april 17, 2008 16 m. balini untitled recent morphological changes of the river panaro (northern italy) doriano castaldini* & alessandro ghinoi* *dipartimento di scienze della terra, università degli studi di modena e reggio emilia, largo s. eufemia 19, i-41100 modena, italy e-mail: doriano.castaldini@unimore.it abstract: castaldini d. & ghinoi a., recent morphological changes of the river panaro (northern italy) (it issn 0394-3356, 2008). this paper describes the morphological changes of the river panaro from the 19t h century to date and provides the relationships between human activity and stream geomorphology. the studies were carried out using historical documents and maps, aerial and satellite imagery taken on various dates, digital treatment of maps and orthophotographs and field surveys. the river panaro has a catchment basin of 1,784 km2 and collects waters from the central section of the northern apennines. it starts from the confluence of the scoltenna and leo torrents and flows down through modena apennines for some 63 km. it then makes its way across the po plain for 85 km until it joins the river po. in the po plain it flows across two distinct sectors with different morphological characteristics: in the upper sector the river runs deep in the alluvial plain, whereas in the mid-lower part it is elevated above the level of the plain, contained within artificial embankments. in the panaro valley, from the 1930s to the 1950s, the river showed a braided pattern which occupied almost the entire flat valley floor. important changes occurred later, due to the downcutting and narrowing of the active channel, which have continued until the present day. in the upper part of the plain., the river occupied a large depression with a braided riverbed at the beginning of the 19th century. in the following periods there was an increase of human interventions along the river (construction of embankments, walls and groynes), in order to reclaim surrounding areas from flooding and turn highwater beds into farming land. this led to narrowing in several stretches of the riverbed, although it still maintained a braided pattern until the 1930s. subsequently, after the 1950s, the braided pattern became canalised and deepened and the shape of the longitudinal profile changed from a hyperbola-type curve to a step-type one. the channel changes in the apennines and in the upper part of the plain were mainly due to gravel excavation along the riverbed. quarrying activities stopped after a law was passed in the early 1980s and, at the same time, fluvial barrages were constructed. on the whole, these hydraulic works reduced the bed load, increasing water erosion power downstream. as a result, the deepening process has continued and a new terrace level has formed in the past 30 years. channel adjustments have led to the change from a braided channel pattern to a transitional one. in the mid-lower part of the plain, the river length has been reduced by 10-11 km (which corresponds to about 13% of its length in this plain sector) by artificial meander cut-offs carried out since the 19th century to reduce flood hazard. in this way, along long stretches of its course, the river panaro has assumed the aspect of an artificial watercourse. since the cut-offs did not adequately reduce flood hazard, “flow regulation systems” were constructed in the area east of modena. it can therefore be stated that the morphology and evolution trend of the river panaro have been conditioned by direct and indirect human activities over the past two centuries, especially after the 1950s, and that its evolution is similar to what has been recorded in other italian rivers riassunto: castaldini d. & ghinoi a., recenti cambiamenti morfologici del fiume panaro (italia settentrionale) (it issn 0394-3356, 2008). il presente articolo descrive i cambiamenti morfologici del fiume panaro a partire dal 19° secolo e illustra le relazioni tra l'attività antropica e la morfologia fluviale. lo studio è stato realizzato analizzando documenti storici, carte, fotoaeree e immagini satellitari di vari periodi, tramite gis, ed eseguendo rilevamenti sul terreno. il f. panaro, che ha un bacino di 1.784 km2, raccoglie le acque dal settore centrale dell'appennino settentrionale e le convoglia nel f. po dopo aver attraversato l'appennino modenese, dove nasce dalla confluenza dei torrenti leo e scoltenna, per 63 km e la pianura padana per 85 km. nella pianura padana il f. panaro si sviluppa in due settori con diverse caratteristiche morfologiche: nel settore di alta pianura scorre incassato mentre nel settore di media-bassa pianura scorre pensile tra argini artificiali. nel tratto vallivo, dagli anni '30 agli anni '50 del secolo scorso, il fiume denotava un alveo a canali intrecciati che occupava quasi l'intero fondovalle. importanti cambiamenti sono intervenuti successivamente in seguito a processi di approfondimento e restringimento dell'alveo che sono continuati sino ad oggi. nel settore di alta pianura, all'inizio del 19° secolo, il fiume occupava una larga depressione con un tracciato a canali anastomizzati. a partire dalla fine di questo secolo, l'aumento degli interventi antropici lungo il fiume (costruzione di argini, muri e pennelli) realizzati per proteggere il territorio dalle esondazioni ed acquisire terreni per l'agricoltura, ha condotto ad un restringimento dell'alveo sebbene abbia mantenuto un tracciato a canali intrecciati sino agli anni '30. successivamente agli anni '50 l'alveo si è approfondito e canalizzato; il profilo longitudinale è passato dalla classica curva a forma di iperbole a quella a gradini. i cambiamenti morfologici dell'alveo del f. panaro sia nel tratto vallivo sia nel tratto di alta pianura sono dovuti principalmente all'attività estrattiva lungo l'alveo, cessata per legge a partire dai primi anni '80, e alla relativa costruzione di briglie. le briglie hanno ridotto il trasporto solido incrementando in tal modo l'energia della corrente nei tratti a valle di queste strutture. il risultato è stato che il processo di approfondimento d'alveo è continuato e un nuovo terrazzo si è formato nell'ultima trentina d'anni. l'evoluzione del fiume ha portato ad un cambiamento d'alveo da una morfologia a canali intrecciati ad una transizionale. nel settore di media e bassa pianura, la lunghezza del fiume è stata ridotta di circa 10-11 km (che corrispondono a circa il 13% del percorso in questo settore) in seguito a tagli di meandri realizzati sin dal 19° secolo per ridurre il pericolo di esondazioni; in questo modo il f. panaro ha assunto in lunghi tratti l'aspetto di corso d'acqua artificiale. poiché i tagli di meandro non hanno ridotto tale pericolo, come testimoniato dalle alluvioni verificatesi dopo la loro realizzazione, ad est di modena sono state costruite delle casse di espansione. in definitiva si può affermare che la morfologia del f. panaro e la sua evoluzione sono stati condizionati direttamente ed indirettamente da interventi antropici succedutisi negli ultimi secoli, ed in particolare a partire dagli anni '50, e che la sua evoluzione è simile a quella riscontrata in altri fiumi italiani. keywords: morphological changes, anthropogenic interventions, river panaro, northern apennines, po plain. parole chiave: cambiamenti morfologici, interventi antropici, fiume panaro, appennino settentrionale, pianura padana. il quaternario italian journal of quaternary sciences 21(1b), 2008 267-278 268 d. castaldini & a. ghinoi 1. introduction it is well known from many studies that in the past few centuries human activity has influenced channel changes and stream morphology all over the world (see le o p o l d, 1973; pe t t s, 1979; hi c k i n, 1983; gr e g o r y, 1987; la j c z a k, 1995; ló c z y, 1997; li e b a u l t & pi e g a y, 2002; herget et al. 2007). as regards italy, channel changes along the river po (the longest watercourse in italy, 652 km), occurring during the 20t h century, are, at least in part, a consequence of river engineering (see govi & turitto, 1993; castaldini & piacente, 1995). the same can be said for the streams enza (pe r e g o, 1988), tidone (fa r a v e l l i & messina, 1997), trebbia and vara (rinaldi et al., 2005) in the northern apennines and rivers dora riparia (franceschetti et al., 1990), piave and brenta (surian, 1999; surian et al., 2005) in the alps. a general outline of the main channel adjustments that have occurred in 27 italian rivers during the past 100 years was given by surian & rinaldi (2003). this paper illustrates the morphological changes of the river panaro (fig. 1) from the 19th century to date and discusses the relationships between human activity and stream morphology. as regards the evolution of the river in previous centuries, see pellegrini m. (1969) and castaldini (1989). studies concerning the recent evolution of the r. panaro go back to 30-40 years ago. in detail, pellegrini & rossi (1967) notice that after a period of flooding or equilibrium, the stretch of the r. panaro, from the lower mountain area as far as the city of modena, has undergone an erosional phase, starting around 1950, which has caused a lowering of the riverbed. quarrying activities within the riverbed have been identified as the main cause of this process, since the authors have noted how the location of quarries correspond to the river stretches subject to erosion; the onset of this process also coincides with gravel and sand extraction on a wider scale. in addition, pe l l e g r i n i m. (1969) notices that some morphological features of the r. panaro, as well as of the nearby r. secchia, tend to have changed: riverbed narrowing, stretching up of the river courses and rejuvenation of the equilibrium profile. these changes are mainly ascribed to artificial causes, such as meander cutoffs and excavation of building materials from riverbeds. pe l l e g r i n i m. et al. (1979) describe the evolution which has taken place in the past decades in the tributaries of the river po in the emilia region. these authors show that the r. panaro is certainly one of the rivers which have undergone major changes due to anthropogenic activities: intense gravel excavation from the riverbed up to the mid-mountain area, subtraction of vast highwater areas for farming practices, construction of embankments in the upper plain area etc. after these studies, though, no significant investigations have been carried out on the evolution of the r. panaro. yet, the simple comparison between the actual morphological situation and the regional technical ma p ( ct r ) of t he emil ia -r o mag n a r eg io n , at a 1:10,000 scale (which is commonly used a as topographic basis for territorial studies) clearly shows that hydrography has undergone remarkable changes also in the past 30 years. in fact, the general representation of morphology, hydrography and vegetation in the ctr second edition corresponds to the situation between 1973 and 1979. therefore, on the one hand this paper aims to be an updating of previous investigations and, on the other hand, it reconstructs the morphological changes of the r. panaro by means of a detailed examination of cartographic and remote sensing documents introduced into a gis. in addition, this research may be considered as a contribution to the outline of channel adjustments in italian rivers, since the river panaro was not considered in the list by surian & rinaldi (2003). 2. geographical, geomorphological and geological setting the river panaro has a catchment basin of 1,784 km2 and collects waters from the central section of the northern apennines. it originates in the mid-modena apennines, at the confluence of the streams scoltenna and leo (altitude of about 320 m a.s.l.) and flows down through modena apennines for some 63 km (fig. 1). after flowing along a flat-bottomed valley, it reaches the po plain at the foot of the apennine chain near vignola (altitude of 110 to 100 m a.s.l.). in the plain, the river panaro flows across two distinct sectors with different morphological characteristics: in the upper sector of the plain, upstream of modena, the river runs deep in the alluvial plain, whereas in the mid-lower part of the plain, it flows elevated over the plain, contained within artificial embankments, as far as the confluence with the river po (altitude of about 10 m a.s.l.). the study area is situated in a temperate climatic zone (type “cfa” of köppen's classification). from the pluviometric viewpoint, it has annual average precipitation ranging from about 1200 mm in the mountain sector to some 700 mm in the plain sector, with seasonal peaks concentrated in autumn and spring, and minimum v alu es in s u mmer ( b o c c o l a r i et a l. , 19 9 8 ) . therefore, the hydrological regime of the r. panaro is characterised by two very similar peaks in the spring (march-april) and autumn (november), and a minimum in summer (august). the main geological units forming the modena apennines are as follows (bettelli et al. 1989): 1) tuscan units, made up of tertiary deep-water turbidites, continuously cropping out along the apennine chain axis. 2) ligurian units made up of deep-sea sediments including jurassic ophiolites followed by thick sequences of cretaceous to eocene calcareous or terrigenous turbidites. 3) the mainly terrigenous epi-ligurian sequences of the middle eocene to the late messinian, unconformably resting on the previously deformed ligurian units. the epi-ligurian sequences and the ligurian units are exposed in the mid-apennines. 4) the belt of plio-quaternary marine terrigenous deposits unconformably overlying the ligurian units and the epi-ligurian sequences cropping out at the apennine margin and dipping under the alluvial deposits of the po plain. the modena plain lies at the foot of the apennine chain which is still in full evolution. at the apennine margin the streams reaching the plain have built up alluvial fans which extend to the north. since they overlap each other, they can be regarded as part of a continuous belt of coarse alluvial deposits spreading all along the apennine foot. remains of old fans appear at the foot of the apennine chain, and are characterised by paleosols and pleistocene aeolian covers (loess), terraced upstream and buried downstream by the holocene alluvia. many ridges formed by the local evolution of ancient streams depart from the foot of the fans, their patterns revealing the recent migration of these rivers. north of the city of modena, depressed areas are located in between the fluvial ridges. the superficial alluvial deposits in the study area were mainly formed during the holocene; their particle-size distribution ranges from gravel to clay (ga s p e r i et al. , 1989; ca s t i g l i o n i et al., 1997; ca s t i g l i o n i & pe l l e g r i n i g.b., 2001). the plain/apennine boundary is purely morpholo269recent morphological changes ... gical as the apennine structures continue towards nne as far as the river po, buried under the quaternary continental sediments. fault or fold displacements have also involved these deposits (pi e r i & gr o p p i, 1981; di dio, 1998). 3. methods and data sources the study was carried out according to the traditional methods used in geomorphology (bibliographic research; research on historical documents and maps, morphological analysis by means of interpretation of aerial photographs an d satellite imagery taken in various periods, morphological field-survey of the present-day river course) as well as methods concerning the digital treatment carried out on maps, aerial photographs and satellite images. the use of digitisers and image processing in geomorphology and especially in fluvial process mapping has been illustrated in several works (see le y s & we r r i t t y, 1999; we s t a w a y et al., 2000; wr i g h t et al. , 2 0 0 0 ) . the technique consists in the elaboration of maps of fluvial features (morphological maps), starting from topographic maps, aerial photographs and satellite images. as t h e r iv er pa n ar o cou rs e h as been s h own accurately on maps only since the 19t h century, this study has focused on the evolution of the last two centuries. the documents listed in tab. 1 have been considered. the topographic maps of the study area, corresponding to different years, have been rasterised in the firs t ph as e. due t o t heir early date of publication, some maps did not present a georeferenced base; it h as t h e ref or e n ot b een possible to introduce them into a gis. subsequently, they were scanned and georeferenced within the arcgis gis. in this way it was possible to measure, with acceptabl e ap pr ox ima t io n , t h e changes taking place in the riverbeds. as regards aerial photographs and satellite images, the method used consisted in interpretation and fig. 1 location of the study area. legend: 1) basin of the river panaro; 2) stretches of the river panaro shown as examples near casona, spilamberto and s. ambrogio; 3) sectors of the river panaro (as: apennine sector; up: upper part of the plain; mlp: mid-lower part of the plain). ubicazione dell'area di studio. legenda: 1) bacino idrografico del fiume panaro; 2) tratti del f. panaro illustrati come esempi presso casona, spilamberto e s. ambrogio; 3) settori del f. panaro (as: settore apenninico; up: alta pianura ; mlp: medio-bassa pianura). digital treatment using photogrammetry techniques, which afterwards allowed the georeferen c e of g eo mo rp h ol og ic al information. a field-survey of the present-day course has been carried out in order to update the features of the stream through geomorphological mapping. 4. morphological changes of the river panaro since the 19th century in this part the morphologi cal ch an g es of t h e r i v er panaro since the 19th century to date are illu strated in detail. they were reconstructed on the basis of the documents listed in table 1. this research and its conclu s ion s wer e s u pp or ted b y analyses carried out on the entire course of the river panaro. the description will be made in chronological sequence, making a division between three sectors: apennine sector (as); upper part of the plain (up); mid-lower part of the plain (mlp). in particular, this paper will focus on the illustration of the channel changes occurring on the most significant partial stretches: casona in the as sector, spilamberto in the up sector and st. ambrogio in the mlp sector (fig. 1). 4.1 channel changes in the apennine sector in the apennine sector the comparison between topographic maps, aerial and satellite imagery and topographic elements currently visible in the field has highlighted substantial changes along the river panaro valley from the first half of the 20t h century (the oldest map examined for this sector are the 1933-35 igm maps). in particular, in the 1930s the river panaro bed showed a braided pattern which occupied almost the entire flat valley bottom; terraces (of small extent) were present only locally, and no significant human dwellings existed (fig. 2a). a very similar situation can be found in the 1954-1955 aerial photographs. important changes are evident in more recent documents. in fact, in the 1970s the river abandons its braided pattern and the river channel gets deeper and narrower, as testified by the formation of side-valley terraces used for farming and human settlements (fig. 2b). some check dams can be found along the river course. the downcutting and narrowing of the active channel has continued until the present day. in detail, besides considerable growth of human activities on the river terraces, the river has undercut its bed forming a new terrace (fig. 2c). this is about 1 m higher than the riverbed and reaches several meters at the apennine margin, just downstream of check dams where the bedrock crops out. this terrace, characterized by dense vegetation, is already visible and developed in the 1988/89 aerial photographs, while it is not present in those of the 1970s. therefore, its formation is likely to date back to the end of the seventies and the beginning of the 1980s. 4.2 upper part of the plain in the first half of the 19t h century the r. panaro occupied a depression in the alluvial plain with a vast extension of deposits and showed a braided pattern (fig. 3a). it is not possible to evaluate the depth between the alluvial plain and the river channels because of lack of information on altimetry in the ca r a n d i n i (1821-1828) maps. the first modest excavations of gravel from the riverbed go back to that period (lombardini, 1865). at the end of the 19t h century (fig. 3b), the river flowed within a depression which, as assessed on the basis of the few altitude points shown, was around 1-2 m lower than the surrounding ground surface. the watercourse still showed braided channels. of course, the trend of the low-water channels had undergone changes compared with the previous period. in this period, the first systematic human interventions along the river (embankments, walls and groynes) were carried out in order to reclaim the surrounding areas from flooding and turn highwater beds into farming land. significant channel changes were recorded in the first half of the 20th century (fig. 3c and 3d), caused by further construction of walls and embankments. this had two consequences: the first was a narrowing of the riverbed (fig. 3d); the second was a result of the first and consisted in a huge aggradation process in the active channel (fig. 4a). nevertheless, the r. panaro maintained its braided pattern. other important human works carried out in this period were the excavation of small gravel pits at the sides of the river. the analysis of t he channel changes for the second half of the 20t h century is much better docu270 table 1 documents considered in this study. igm: italian military geographic institute; gai: aerial italian group; ctr: regional technical maps (ctr) of emilia-romagna region; rer: emilia-romagna region; documenti utilizzati nel presente studio: igm: istituto geografico militare italiano; gai: gruppo aereo italiano; ctr: carta tecnica della regione emilia -romagna; rer: regione emilia romagna. type of document age scale/resolution note carandini maps 1821 1828 1:50,000 colour igm maps 1881 1894 1:25,000 black & white igm maps 1911 1914 1:25,000 black & white igm maps 1933 1935 1:25,000 black & white gai aerial photographs 1954 1955 1:33,000 black & white rer aerial photographs 1973 1:15,000 black & white ctr maps 1973 1978 1:10,000 black & white rer aerial photographs 1978 1:20,000 colour ctr maps 1985 1986 1:10,000 black & white volo italia aerial photographs 1988 1989 1:70,000 black & white volo italia 2000 orthophotographs 2000 1 m colour quick bird satellite orthophotographs 2003 0.6 m black & white d. castaldini & a. ghinoi 271recent morphological changes ... mented thanks to ctr maps, new igm maps, aerial photographs, satellite imagery and field surveys. they show important human interventions along the river which have influenced stream morphology (fig. 3e). in this period, quarrying activities and fluvial barrages influenced channel changes. these factors produced the same effects on the river: deepening and canalisation of the riverbed. after the 1950s, the considerable expansion of urban and industrial areas required an increase of building materials and therefore of quarrying activities; these activities were concentrated inside and in proximity of the riverbed. the first effect of excavations inside the riverbed was the removal of the superficial coarse alluvial deposits which brought to the surface alluvial material of different particle size that was easily eroded by the stream. this resulted in increased deepening of the riverbeds and a new channel morphology, which undermi272 d. castaldini & a. ghinoi fig. 3 morphological sketch of the r. panaro in the upper part of the plain near spilamberto. legend: a) first half of 19th century (elaborated from carandini, 1821-28 maps); b) second half of 19th century (from the 1884 igm map); c) 1911 and d) 1935 (from the 1911 and 1935 igm maps); e) second half of 20th century (from the 1978 ctr maps and aerial photographs); f) present situation (from the 2003 quick-bird satellite imagery and field surveys); 1) river channel; 2) fluvial scarp; 3) artificial scarp; 4) artificial embankment; 5) quarrying area (a: active; b: abandoned); 6) check dam; 7) bridge; 8) built-up area. carta geomorfologica schematica del f. panaro nell'alta pianura presso spilamberto. legenda: a) prima metà del 19° secolo (elaborata sulla base della cartografia carandini, 1821-28; b) seconda metà del 19° secolo (dalla cartografia igm del 1884; c) 1911 e d)1935 (dalla relativa cartografia igm); e) prima metà del 20° secolo (dalla ctr e da fotoaeree del 1978); f) attuale (dalle immagini del satellite quick-bird del 2003 e da rilevamenti sul terreno); 1) alveo fluviale; 2) scarpata fluviale; 3) scarpata artificiale; 4) argine artificiale; 5) area di cava (a: attiva; b: abbandonata); 6) briglia; 7) ponte; 8) area antropizzata. ned or damaged bridge piers at marano, vignola, spilamber t o and s. d on n in o (mo to rway brid ge) . deepening of over 6 m was recorded near spilamberto bridge (fig. 4b). in order to overcome these unforeseen problems, various check dams were constructed. however, these hydraulic structures have stopped riverbed deepening only locally. in fact, acting as local base levels, these barrages have favoured aggradation processes and the re-deposition of the alluvial cover only in the upstream tracts (fig. 4c). on the whole, check dams have reduced bed load, thus increasing water erosion power downstream. the result was that deepening processes have continued in the stretches downstream of the barrages. riverbed deepening also introduced an important modification. in fact, the reduction of lateral movements caused by downcutting produced a change in morphology from a braided to a wandering pattern. the deepening process was particularly marked in the 1970s. since the 1980s the river has been flowing within a single riverbed (or with very few channels) and the process of downcutting has continued accompanied by a marked narrowing of the active channel (fig. 3f). the deepening, together with the construction of check dams, has also modified the longitudinal profile of the riverbed from a hyperbola-type curve to a step-type one (fig. 5). quarrying activities, located at the sides of the river, have irreversibly altered the natural morphological features of the depression and have dismembered or destroyed the hydraulic defence works constructed since the end of the 19th century. in this way the boundary depression has changed from a “natural” type to an “artificial” type. in the present day, the r. panaro shows a transitional pattern, mainly confined within a single flow channel still characterised by intense downcutting. in order to solve the impacts of quarrying activities on the landscape, some measures have been taken by the province administration board in recent decades. within the framework of a strategy for environmental protection and improvement, local administrations have concentrated their efforts on reclaiming quarrying areas. in this way many of them have become nature protection areas where industrial activities are no longer permitted (provincia di modena, 2003). in short, especially after the 1950s, the river panaro switched from a braided riverbed to a canalised course subject to considerable deepening and narrowing. this trend has lasted up to the present. for instance, near spilamberto, a deepening of 8-9 m and a narrowing of about 390 m (56%) of channel width has been recorded in the past 120 years (fig. 6). 4.3 mid-lower part of the plain in this part of the plain, in the first half of the 19th century, the r. panaro showed several, well developed meanders, with a bend radius of up to 200 m; it also showed alternate channel width: from 80 m (slightly winding stretches) up to 500 m wide (with large highwater beds). in this sector the river flowed within artificial embankments which were “uplifted and strengthened” during this period (lo m b a r d i n i, 1865); this means that floods were a hydrological hazard. at the end of the 19th century, the r. panaro still showed several meanders, even if it was shortened at the beginning of 1889 by about 5.5 km between finale emilia and bondeno. moreover, some meanders appear to have been straightened near its outlet, with a reduction of the watercourse length of about 2 km. in this way the r. panaro was shortened by about 7-8 km. the meander cutoffs were mainly carried out in order to reduce the highwater level along the straightened reach, where the sinuous course caused a slowdown of the flow, and therefore to mitigate flood hazard. in fact the river panaro, in the 19t h c e n t u r y , flooded several times (in 1812, 1813, 1842, 1852, 1862, 1868, 1872 and 1887) (ca s t a l d i n i, 2006). these interventions proved ineffective, as shown by floods which later occurred: after the artificial cutoffs and before the end of the century, the r. panaro flooded again in october 1889 and october 1897. of course, meander cutoffs did not eliminate flood hazard but only transfer273 fig. 4 the r. panaro channel at the bridge of spilamberto: a) in the 1930 circa (by pellegrini m. et al., 1979); b) in the 1967 (by pellegrini m. & rossi, 1967); c) in the 2004 (photo by d. castaldini). l'alveo del f. panaro presso il ponte di spilamberto. a) nel 1930 circa (da pellegrini m. et al. 1979); b) nel 1967 (cfr. by pellegrinii m. & rossi, 1967); c) nel 2004 (foto d. castaldini). a) 1930 b) 1967 c) 2004 recent morphological changes ... red the problem to the river reach downstream of the cutoffs. in the first half of the 20t h century, the course of the r. panaro remained practically identical to the course of the 19th century. in this century the r. panaro flooded several times in the area of modena: in 1928, 1939, 1949, 1951, 1952, 1956, 1960, 1964, 1966, 1969, 1972 and 1973 (ca s t a l d i n i, 2006). in order to reduce flood hazard, the latest meanders cutoff was made in the early 1970s when the r. panaro was shortened by four meanders (a le n gt h o f a bo u t 3 k m) n ear st . ambrogio, east of modena (fig. 7 and 8). but also this work proved ineffective, as testified by the flood which struck the territory of finale emilia in november 1982. t h er efo re , a “fl ow re gu l at io n system” was planned and constructed to the east of modena, at the boundary between the upper and middle sectors of the plain, adjacent to the river course, in order to better control hydrogeological hazard (castaldini & pellegrini m., 1989). the flow regulation system is located where r. panaro flows inside its natural depression, that is approximately 2 km wide, previously used as quarrying areas (fig. 8). this structure, operating since 1985, consists principally of a regulating dam built across the riverbed and a storage basin (which allows the store of about 24 million m3 of water) almost completely confined by embankments about 6 km long and 4 to 5 m high. during lowwater periods, the water is discharged through mouths located in the regulating dam at the same level as the riverbed. during highwater events, no more than a limited amount could be discharged through the dam's mouths. excess water is stored upstream of the regulating dam, producing an increase in water level and regulating the flow downstream. the flow regulation system was completed in november 1999. the most 274 d. castaldini & a. ghinoi fig. 5 modification of the longitudinal profile of the r. panaro in the upper part of the plain (between the vignola bridge and s. ambrogio bridge). legend: 1) longitudinal profile of the plain level in 1973-1978 (elaborated from the ctr maps at a 1:10,000 scale); 2) longitudinal profile of the r. panaro channel in the 1960s (from pellegrini m. & rossi,i, 1967); 3) longitudinal profile of the r. panaro channel in 1978 (elaborated from the ctr maps at 1:10,000 scale); 4) check dam: 5) bedrock outcrop. the vertical scale is exaggerated with respect to the longitudinal scale. modificazione del profilo longitudinale del fiume panaro tra vignola e il ponte di sant'ambrogio sulla via emilia. legenda: 1) profilo longitudinale del livello della pianura nel 1973-1978 (elaborato dalle ctr a scala 1:10.000); 2) profilo longitudinale dell'alveo del panaro negli anni '60 (da pellegrini m. & rossi,, 1967); 3) profilo longitudinale dell'alveo del panaro nel 1973-1978 (elaborato dalle ctr a scala 1:10.000); 4) briglia: 5) affioramento del substrato. la scala delle altezze è esagerata rispetto a quella delle lunghezze. fig. 6 trends of the channel width in the stretch of the r. panaro in the upper part of the plain near spilamberto since the end of 19th century (the stretch is about 4 km long). channel width was measured on maps, aerial and satellite images as indicated in tab. 1. variazio ni della larghezza dell'alveo del f . panaro nell'alta pianura pr esso spilamberto dalla fine del 19° secolo (il tratto d'alveo è lungo circa 4 km). la larghezza è stata misurata su documenti cartografici, fotoaeree e immagini satellitari indicati in tab. 1. important function of this large hydraulic work is to reduce flood peaks; that is, they intervene on a very limited water capacity but with a high hydrometric level. similar structures were also built on other watercourses of the emilia-romagna region, such as the secchia river to the west of modena. the above mentioned deepening processes of the upper part of the plain have affected also the stretches north of modena, where the r. panaro flows as an elevated river within artificial embankments. moreover fluvial erosion takes place in correspondence with concave banks, causing their undermining which in some places leads to bank retreat and soil slips. in order to curb bank erosion, rockfill protection structures have been set up along many reaches. in several reaches both the banks of the r. panaro are covered by thick riverine vegetation which reduces the water flow section with an increase in hydraulic hazard. 5. conclusions the morphological changes of the r. panaro from the 19th century to date were reconstructed on the basis of reliable and detailed maps, aerial and satellite imagery and field surveys. the morphological changes were examined in three distinct sectors, which are the flat bottom valley in the apennine sector, the upper part of the plain, where the river cuts through the alluvial plain, and the mid-lower plain sector, where it flows as an elevated water course within artificial embankments. in the 19th century all anthropogenic interventions described by c a s t i g l i o n i & p e l l e g r i n i g . b . (2001) are furthermore accentuated in the po plain. a new phenomenon, consisting of ever i ncreas ing h ig hwat er even ts takes place starting from 1705, as recorded by ins tru men tal measurements: each highwater event tends to overcome the maximum hydrometric levels of the previous one (for r. panaro, see lo m b a r d i n i, 1865). floods are disastrous and the economies of pre-unity italian states and subsequently of the newly founded kingdom of italy were at the end of their resources. the establishment of land reclamation agencies in this country is the consequence of this situation. among the hydraulic engineers of th at period a very heated discussion started about the causes of th is ph en omenon . according to lo m b a r d i n i ( 1 8 6 5 ) , the causes were to be found exclu siv ely in defores tat ion . other experts, though, noticed that also the riverbed bottom alt itu des were pr ogres sively increasing. all the rivers' alluvial deposits, which will be removed in the second half of the 20th century, can be ascribed to the end of 16th century-first half of 20th century period. the climatic meaning of this considerable depositional phase is probably related to the little ice age (see ferrari & pellegrini m., 2007 and annexed bibliography). research aimed to show how the deepening process of the r. panaro, which became very evident in the 1960s, is an alarming phenomenon which has undermined or damaged bridges, piers and weirs (pellegrini m. & rossi, 1967; pellegrini m., 1969; pellegrini m. et al., 1979) and has continued up to recent decades. in fact, it has been demonstrated that a new terrace level was formed in the past 30 years, both in the apennine sector and in the upper part of the plain. pe l l e g r i n i m. & ro s s i (1967) believed that the tendency of watercourses to deepen their riverbeds might have a positive aspect since, by increasing the river section, it also reduced the dangers of flooding even in the stretch where the river is elevated over the surrounding plain. subsequently, though, pe l l e g r i n i m. et al. (1979) showed that the new type of riverbed had caused a change in water runoff dynamics (decrease of highwater events with tendential increase of hydrometric levels but unchanged integral flow rate). according to these authors, this new hydraulic regime, which was a direct consequence of the altered morphological conditions of the river, should be considered the cause of the frequent inundations occurring in the 1960s and 1970s near modena (1960, 1964, 1966, 1969, 1972 and 1973). 275 fig. 7 aerial photograph of the r. panaro near s. ambrogio, east of modena. it flows from the left (south) to the right (north); meander cut-offs carried out in the early 1970s are evident (photo by d. castaldini). foto dall'aereo del f. panaro presso s. ambrogio, a est di modena. il fiume scorre da sinistra (sud) verso destra (nord); risultano evidenti i tagli di meandro effettuati agli inizi degli anni '70 (foto d. castaldini). recent morphological changes ... in order to overcome the downcutting process, various check dams were constructed along the river, but this solution proved ineffective as witnessed by the fact that this phenomenon has continued also in the last three decades. at present new types of barrages allowing the passage of bed load are being designed. they are equipped with small hydroelectric plants located along the sides of the river in order to exploit the morphological step of these check dams for the activation of water turbines. in general, channel adjustments since the 19t h century have led to a change in the channel pattern from braided to transitional. this evolution is similar to what has been recorded by su r i a n & ri n a l d i ( 2 0 0 3 ; 2004) in other italian rivers. as for the causes of these modifications mainly limited to the past 50 years we fully agree with the remarks of the previously mentioned authors and the early authors who studied the river panaro. according to their views, the effects of natural causes (such as uplift of the apennine chain, subsidence of the alluvial plain, climate changes) seem to have played a minimal role, since they have had only gradual repercussions on the evolution of watercourses. on the contrary, emphasis is given to anthropogenic activities affecting the riverbeds (such as quarrying and construction of check dams). nevertheless, other causes for changes are: i) hydraulic non-equilibrium between new flow rates (concentration and increase of qmax) and canalised riverbed; ii) along long stretches water stream erodes weaker bedrock formations with lower roughness index (marine clays of the plio-pleistocene cycle, alluvial marine clays, previously underlying or juxtaposed to gravel deposits; highly weathered gravels with matrix of pleistocene deposits; see gasperi et al., 1989). iii) absence of bed load for the hydraulic arrangement of the basin in the 1950 to date period. 276 d. castaldini & a. ghinoi fig. 8 morphological sketch of the r. panaro near s. ambrogio (east of modena) in the 1930s (elaborated from the 1933 igm map) and at present (elaborated from the 2003 quick-bird satellite image and field survey). to be noted: in the northern sector, the meander cut-offs carried out in the early 1970s and, in the southern sector, the flow regulation system. legend: 1) river channel; 2) paleo-riverbed; 3) fluvial scarp (in some stretches remodelled by man's intervention); 4) artificial embankment; 5) check dam; 6) dam of the flow regulation system; 7) storage basin of the flow regulation system; 8) depleted quarry area (a: dry floor; b: flooded floor); 9) bridge; 10) built-up area. carta geomorfologica schematica del f. panaro presso s. ambrogio, (est di modena) negli anni '30 (elaborata sulla base della cartografia igm del 1934) e nel presente (elaborata sulla base delle immagini del satellite quick bird del 2003 e di rilevamenti sul terreno). legenda: 1) alveo fluviale; 2) paleoalveo; 3) scarpata fluviale (in qualche tratto rimodellata dall'antropizzazione) ; 4) argine; 5) briglia; 6) manufatto regolatore della cassa di espansione; 7) bacino d'esondazione della cassa di espansione; 8) area di cava abbandonata (a: a fondo asciutto; b: a fondo allagato); 9) ponte; 10) area antropizzata. in the mid-lower plain sector, the present course of the r. panaro was conditioned by the meander cutoffs carried out in the late 19t h century and at the beginning of the 1970s. in this study it was calculated that meander cutoffs reduced the length of the r. panaro by about 10-11 km. these length reductions correspond to about 13% of its length in this plain sector before cutoffs (tab. 2). thus, like other rivers of the mid-lower plain south of the r. po, r. panaro has taken on the appearance of an artificial watercourse for long stretches, owing to a decrease of its width and length and the disappearance of its highwater beds. these morphological changes, combined with undercutting processes, which are active also in the mid-lower plain sector, have obviously caused variations of the river's hydrometric characteristics (runoff time, height and flow rate of highwater events). since the cutoffs did not reduce flood hazard adequately, which was the primary goal of these interventions, “flow regulation systems” were constructed in the area east of modena along the river. obviously, also the construction of the flow-regulation system has contributed to modifying both the natural morphology of the riverbeds and water runoff dynamics. according to investigations carried out and data collected, it can be forecast that the r. panaro riverbed will take some more decades before finding a new equilibrium following the changes that have affected it over 50 years; although the ever-present anthropogenic activities will probably never allow a new equilibrium to be fully attained. it can be stated that the present morphology and evolution trend of the river panaro have been conditioned by direct and indirect human intervention over the past centuries, especially since the 1950s. therefore, human action as a morphogenetic agent has been once more confirmed. 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( 20 0 0 ) evaluation of multispectral, fine scale digital imagery as a tool for mapping stream morphology. geomorphology, 33, pp. 107-120. 278 ms. ricevuto il 30 gennaio 2008 testo definitivo ricevuto il 5 maggio 2008 ms. received: january 30, 2008 final text received: may 5, 2008 d. castaldini & a. ghinoi amq34(2) 213-235 terlato et al def immrid.pdf available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 34 (2), 2021, 213-235 late neanderthal subsistence at san bernardino cave (berici hills northeastern italy) inferred from zooarchaeological data. gabriele terlato1,2, valentina lubrano2, matteo romandini2,3, ana b. marín-arroyo1,4, stefano benazzi3,5, marco peresani2,6,7 1 grupo de i+d+i evoadapta, dpto. ciencias históricas. universidad de cantabria, spain. 2 dipartimento degli studi umanistici, sezione di scienze preistoriche e antropologiche, università degli studi di ferrara, italy. 3 dipartimento di beni culturali, università di bologna, italy 4 department of archaeology, university of cambridge, uk 5 department of human evolution, max planck institute for evolutionary anthropology, germany. 6 istituto di geologia ambientale e geoingegneria, cnr, italy. 7 accademia olimpica, vicenza, italy. corresponding author: m. peresani <marco.peresani@unife.it> abstract: north-eastern italy is a key region for the study of neanderthal way of life over a wide timeframe, as attested by over 20 middle palaeolithic multi-layered sites in caves, rock shelters and at open-air sites. here we contribute to increase our understanding of neanderthal subsistence strategies through the study of the faunal assemblage of unit ii dated to the first half of marine isotopic stage 3 (mis3), from san bernardino cave. the site is located in the berici hills, at low altitude near the edge of a karstic plateau dissected by valleys and delimited by the alluvial lowland. zooarchaeological and taphonomic analyses suggest that neanderthal groups were the primary agent for the accumulation of mammal remains, and that hunting mainly focused on ungulates, such as cervus elaphus and capreolus capreolus. forested environment sustained by mild climatic conditions is also inferred by micromammals evidence. our data suggest a selective transport of the prey even for the roe deer which might have implied a long distance transportation from the site. also, it might have been related to the age of the prey or to multiple preys hunted in a single episode. the bayesian method applied to the analysis of skeletal profiles shows a high level of attrition at the site and a greater degree of processing appendicular skeleton. neanderthals used san bernardino cave as a place where carcasses processing was finalized, after an initial process at the kill-site, and then prepared for consumption. also, discarded bones were used for lithic manufacturing. the san bernardino evidence can be compared with productive systems for exploiting available ungulate game from other regional-scale mis 3 middle palaeolithic sites. keywords: neanderthal subsistence, middle paleolithic, mis 3, northeastern italy, zooarchaeology. 1. introduction one of the main issues to fully understand how neanderthals were able to survive for more than 250,000 years across eurasia is the reconstruction of their diet and subsistence strategies. studying the fauna remains helps to determine anthropogenic behaviour and to accurately understand the subsistence and adaptation patterns used to exploit different ecological niches (stiner, 1994; bocherens, 2009; ready, 2010; gaudzinski-windheuser & roebroeks, 2011; morin et al., 2016; jaouen et al., 2019). however, subsistence behaviour presents specific differences and adaptations between geographical areas and sites, highlighting the importance of the availability and richness of nearby biotopes as much as the functionality of the settlements. zooarchaeological evidence attests, for example, the exploitation of small game, birds, and aquatic resources (brown et al., 2011; cortés-sánchez et al., 2011; blasco & fernández peris, 2012; cochard et al., 2012; blasco et al., 2013; fiore et al., 2016; gómez-olivencia et al., 2018; nabais, 2018; morin et al., 2019; marín el al., 2019; zilhão et al., 2020; guillaud et al., 2021 among others), alongside with the predation and consumption of bears (romandini et al., 2018a). despite this broad diet spectrum, the neanderthals’ main animal protein sources were medium and large-sized herbivores. in general, in late middle paleolithic contexts, undisputable records had proven how neanderthals targeted, butchered and consumed a wide variety of ungulates (patoumathis, 2000; fiore et al., 2004; costamagno et al., 2006; rendu, 2010; rosell et al., 2012; ready, 2013; salazar-garcía et al., 2013; yravedra & cobo-sánchez, 2015; sanz et al., 2019). such scenario does not exclude continental and peninsular italy, where, in recent years, new information about late neanderthal groups’ subsistence behaviour and mobility has been acquired (boscato et al., 2011; peresani, 2011; romandini et al., 2014, 2018a, 2018b, 2020a; fiore et al., 2016; boscato, 2017; holt et al., https://doi.org/10.26382/amq.2021.10 214 terlato g. et al. 2019; moroni et al., 2019; terlato et al., 2019; spagnolo et al., 2020; peretto et al., 2020), thus providing more data on these issues. notably, in the north of italy archaeologists uncovered a considerable number of rock shelters and caves yielding evidence of human occupation during middle and late pleistocene (peresani, 2011; margaritora et al., 2020). these sites are settled within the ecological corridor bounded by the apennine, alpine and dalmatian mountain ranges and the adriatic sea. such a peculiar geographic location is crucial for the understanding of regional differences in mammals’ acquisition and exploitation by neanderthals. despite the abundance of archaeological sites, only few of them yielded animal bones. moreover, not all of them have been analysed with a consistent zooarchaeological approach to assess everywhere the taphonomy, mortality patterns, skeletal profiles, carcass transport, carnivore activities, and so on (fiore et al., 2004; miracle, 2005; thun-hohenstein, 2006; romandini et al., 2014, 2018a, b, 2020a; thun-hohenstein et al., 2018; terlato et al., 2019). this lack of data limits analytical comparisons of neanderthal strategies at a regional and at a larger scale. thus, within such a discontinued and fragmented framework, new zooarchaeological studies are crucial to provide new data on neanderthal groups’ subsistence. to further contribute to the diet and subsistence patterns achieved by neanderthals in southern alps foreland during late mis3, we present the analysis of the faunal assemblage of unit ii of san bernardino cave. this cave was excavated during 1960 and 1986-95 and displayed a cultural sequence rich in lithic implements and faunal remains. we have focused on taxonomical representation, prey selection, skeletal part representations and carcass processing in order to define the site functionality and to compare it with other sites from the regional context. 2. san bernardino cave in the mis 3 landscape 2.1. the subalpine area of the southeastern alps: physical and ecological setting san bernardino cave lies in the foreland of the eastern italian alps. this mountain range represents a physical and environmental threshold where ice fields and alpine glaciers developed during cold stages of the middle and late pleistocene, and where temperate vegetation restored during warm phases. the alpine foreland is a vast alluvial plain originated since the middle pleistocene from the po and adige rivers, other minor waterways, and the ones of the friulian-venetian plain (fontana et al., 2014). concerning this latter, the area also includes hills of different geological origins, like the berici hills and the cone-shaped volcanic reliefs of the euganean hills, which were separated by the spreading outwash of the plain. the berici hills are a karstic plateau with a maximum altitude of 440 m a.s.l., a honeycomb of sinkholes and depressions shaping an extremely uneven topography, scattered by rock peaks and blocks affected by surface dissolution. the plateau is dissected by depressed systems (e.g., the fimon, liona, and calto valleys) characterised by pocketvalleys where ephemeral streams produced swampy environments and fed historic mills. the slopes are steep all around. to the east, a steep slope with rock cliffs connects the plateau to the alluvial lowlands that were occupied by marshes and swamps during the pleistocene and most of the holocene (monegato et al., 2011). to the west, the plateau gradually connects to the plain. ecological conditions during the first half of mis3 recorded the presence of open birch-conifer forests, xerophytic scrubs and steppe. episodes of conifer forests contraction and steppe communities expansion were documented, in alternation with mixed conifer (pinus and picea) betula forests (pini et al., 2009, 2010) and with reduced warm-temperate component (tilia) which however persisted up to ca. 40 ka (pini et al., 2010; badino et al., 2020). rainfall and humid conditions in the southeastern alpine foreland favored by the glaciated alps have also been confirmed by micromammal assemblages in the berici hills at broion cave and san bernardino cave and in the monti lessini area at fumane cave (lópez-garcía et al., 2015, 2017, 2019). 2.2. san bernardino cave san bernardino cave is situated on the eastern slope of the berici at 135 m above sea-level, facing the alluvial plain of bacchiglione river and the western side of the euganean hills (fig. 1). besides san bernardino, other middle palaeolithic caves and shelters open in the same area: broion cave and broion rockshelter (peresani et al., 2019; romandini et al., 2020b), de nadale cave (jéquier et al., 2015; livraghi et al., 2021), paina cave (bartolomei et al., 1987-88). san bernardino cave is 41 m long, 7 m wide and 9 m high and originated from the widening of deep, se-nw oriented fractures produced by thermoclastic processes and chemical dissolution. the natural morphology of san bernardino has been modified along time. the cave was used as a hermitage since medieval times and settled by members of the franciscan order. during the late middle ages or even afterwards prehistoric deposits were partly dismantled by the construction of a wall sealing the entrance of the cave, as also attested by a modern human tooth dated to 1420-1480 cal ad (benazzi et al., 2014a). all along the modern age, the inner cavity was almost totally emptied from the quarrying of the infill. after the discovery of pleistocene bones (fabiani, 1902-03), the first phase of archaeological investigations was coordinated by p. leonardi in the sixties in the medieval wall facing area. the excavations uncovered a pleistocene sequence with faunal remains and lithic industries (leonardi, 1958-1959; leonardi & broglio, 1960-1961). a second phase in the excavation was coordinated by a. broglio and m. peresani between 1986 and 1995, allowing to re-examine the stratigraphic series from the inner and the outer zones (peresani, 1995-1996). the deposit is a complex sedimentary body shaped like an elongated prism, extending from inside to partly outside the cave. it is a remnant of the lower part of the sediments that originally filled the cave. at present, the sedimentary sequence is 4.5 m thick and includes eight stratigraphic units with sub-horizontal bedding, which gradually bend outside the cave (fig. 2). these record the succession of three main paleoclimatic 215 late neanderthal subsistence from zooarchaeology at san bernardino cave cycles shifting from temperate to dry/cold conditions: cycle 1 (mis 7c/b mis 6, units viii to vii); cycle 2 (mis 5d and b mis 4, units v to iv) and cycle 3 (mis 3 mis 2? units iii to i) (cassoli & tagliacozzo, 1994; lópez-garcía et al., 2017). u/th and esr dates range from the middle/late pleistocene (units viii-vii, ca. 214 and 154 ka; gruppioni, 2003; picin et al., 2013) to the late pleistocene for unit ii: 52±5 ka bp, 38±5 ka bp and 33±5 ka bp (peresani, 2001). in addition to a first radiocarbon date at >40ka bp produced in the nineties (peresani, 2001), two new dated bones, one of a bos/ bison (sb42) and another one of a large cervidae (alces/megaloceros) (sb918), both with anthropogenic marks from unit ii, yielded >48.6 ka bp (oxa-40121) and 45.9±2900 ka bp (oxa-40203) (tab. 1). thus, they confirmed that the archaeological content is not younger than the first half of mis 3. a osl dating program is ongoing to support the chronological layout of the sedimentary sequence from unit viii up to unit iv. unit ii, the focus of this paper, is situated at the entrance of the cave and was totally excavated over an area of 20 sqm extending below the medieval wall as well. unit ii (fig. 2) thickens up to 40 cm, it includes different sublayers named 1, 2, 3, 4a, 4b and 4c, and it records an increase in the density of anthropogenic evidence faunal remains, lithic artefacts, and hearths in comparison with the underlying units iii, iv and v. a previous taxonomic study of the macromammal association (cassoli & tagliacozzo, 1994) showed the presence of a broad variety of mammal species such as roe deer, red deer, moose, wild boar and bovines (terlato et al., 2019), while cave bear was the most abundant carnivore. taphonomic analysis of a restricted sample of large ungulate bones, revealed traces of disarticulation, defleshing and the use of bone fragments as retouchers (malerba & giacobini, 1998). lithic industry in unit ii is featured by intensive exploitation of local and exogenous chert, responsible for reduction in size of cores, flakes and retouched tools. flake-manufacture was based on the exclusive application of recurrent unidirectional and centripete levallois modalities (peresani, 1996; porraz & peresani, 2006). moreover, although many tools were shaped at the cave, a significant number of them had been introduced at different stages of reduction. it has been hypothesized that such exploitation might be linked to long-term fig. 1 geographical location of san bernardino cave in north-eastern italy. tab. 1 new radiocarbon dates from unit ii of san bernardino cave. pm: percussion marks; cm: cut marks. ber of individuals) (klein & cruz-uribe, 1984; grayson, 1984; lyman, 1994) and mau (minimum animal units) (binford, 1984). %mau was calculated by dividing each mau by the highest mau value of the assemblage. a 100% representation of all body parts would infer the presence of complete animal bodies. the assemblage diversity was then examined through the inverse of simpson’s index. this index measures both the richness (n-types) and evenness (proportionality) of the kind of prey characterizing the diet (simpson, 1949). the lower the resultant value, the more the assemblage involved is dominated by a single taxon and a narrow diet (magurran, 1988). for regional comparison of hunting preferences, correspondence analysis was employed. to evaluate the prey transport strategies and the intensity of the subsequent attrition, bivariate correlations between %mau and different indices (binford, 1978; metcalfe & jones, 1988; marín-arroyo, 2009a; morin & ready, 2013) were applied: %mau and mgui (modified general utility index binford, 1978), fui (food utility index metcalfe & jones, 1988), cfui (corrected food utility index morin & ready 2013) to define strategies employed in the use or transport of animal carcass; %mau and maximum bone density (lam et al., 1999) to assess the influence of destructive processes in the faunal assemblage. in order to determine if the bone breakage patterns were the result of marrow extraction, correlations between %mau and the marrow index (binford, 1978) were calculated. in addition, %mau of the high survival elements was correlated with the unsaturated marrow index (umi) proposed by morin (2007). spearman’s coefficient of correlation was used to test the quantitative validity of these correlations and to determine the level of statistical significance (p) thereof. furthermore, to overcome the limitations of previous indices to evaluate the skeletal profiles and attrition at the site, a bayesian approach was applied (marín-arroyo & ocio, 2017). this method considers two parameters, alpha (α) and beta (β), that are active during the formation of the assemblage. the former, transport preference (α), can take any value between -1 (>axial contribution) and 1 (>appendicular contribution) based on butchering efficiency in skeletal elements. the latter, degree of attrition (β), which follows the definition established by rogers (2000 a, b), and relates the survivorship of bone element to their maximum bone density. this method aims specifically to overcome the problem of equifinality in skeletal profile interpretations, analysing two factors simultaneously. animals’ age at death was estimated on the basis of the time of eruption, the replacement of teeth, and the degree of dental wear, as well as the stage of the bone epiphyseal fusion. habermehl (1961), aitken (1974), mariezkurrena (1983), azorit et al (2002), d’errico & vanhaeren (2002) and tomé and vigne (2003) were used for calculating the age of cervus elaphus and capreolus capreolus. once the age at death was determined, individuals were grouped into five age groups: i (infant animals with deciduous teeth), j (juvenile lightly worn deciduous teeth and erupted m1); subad (sub-adult animals with moderately worn deciduous teeth and erupted m2); ad (adult all erupted permahuman occupations (peresani, 1995-1996). most of these artefacts were made of finely textured chert collected in the surroundings (1-5 km), together with chert of similar quality supplied from farther sources (15-20 km) in the euganean hills up to the central-western monti lessini (80 km) (peresani, 1996). levallois end and by-products were shaped in a wide range variety of retouched tools, like simple, double and convergent scrapers, while transverse scrapers were made from cortical, centripetal levallois flakes and other flakes (peresani, 1995-1996). denticulates and points sorted in different forms and sizes (peresani, 1995-1996; picin et al., 2010, 2013), in contrast, are rare. the attribution of levallois technology and/or mousterian tools to late neanderthals exploiting this region during mis 3 is proven by the association with human remains from fumane cave (benazzi et al., 2014b), broion rockshelter (romandini et al., 2020b) and tagliente rockshelter (arnaud et al., 2016). 3. materials and methods our analysis concerned the bone assemblage from unit ii. the remains were recovered during fieldwork carried on in 1959-1964 (bartolomei, 1960) and 19861995 (broglio & peresani, 1992), using a main grid of one square meter divided in nine smaller squares. sediments were wet sieved through superimposed mesh from 5 to 0.5 mm. the faunal remains were systematically recovered in situ during the excavation process and after wet-sieving the sediments. following cassoli & tagliacozzo’s taxonomical study (1994) and a preliminar taphonomical observation (malerba & giacobini, 1998), a zooarchaeological re-examination of bovids remains and a first analysis of small mammal bones were performed by terlato et al. (2019) and romandini et al. (2018b) respectively. each of these works used the same methodological approaches for taphonomy studies to evaluate the whole assemblage. overall, 9,429 faunal remains were scrutinized for this analysis. the complete alpine fauna reference collection of the section of prehistoric and anthropological science at university of ferrara and barone’s (1976) reference were used for taxonomic identification and for anatomical nomenclature, respectively. in order to include in the study bones that could not be identified taxonomically by any diagnostic landmark, all the remains have been grouped into four weight sizes classes, based on the modification of the criteria proposed by bunn (1986): (1) small-sized mammals weighing <20 kg (lagomorphs, rodents and small carnivores); (2) medium-sized animals weighing between 20 and 100 kg (i.e. caprids, capreolus capreolus, sus scrofa, canis lupus); (3) medium-large sized animals weighing between 100 and 300 kg (i.e. cervus elaphus, ursidae; panthera pardus); (4) large animals weighing >300 kg (i.e. alces alces, megaloceros giganteus, large bovids). the identified elements were quantified using the following measures: nr (number of remains); nisp (number of identified specimens) (grayson, 1984); mne (minimum number of elements) has been counted considering side, body size and ontogeny (klein & cruz-uribe, 1984; binford, 1984); mni (minimum num 216 terlato g. et al. guished by those made by carnivores (coil et al., 2020) according to diagnostic characteristics: ventral face with point of detachments and bulb; greater breadth than length; absence or reducing of cortical surface. burnt damages were recorded in terms of presence/absence (naked eye) and into three colour stages (stiner et al., 1995): mainly brown (lightly burnt), black (carbonized), grey to white (calcinated). carnivore marks were classified as follows: pits, scores, punctures, furrowing, gnawing and corrosion of gastric acid (fisher, 1995; domínguez-rodrigo & piqueras, 2003; domínguezrodrigo & barba, 2006). finally, the study of bone retouchers was carried out following mallye et al., (2012) and mozota holgueras (2012). 4. results 4.1. bone assemblage the analyzed assemblage consists of 9,421 remains of mammals, three of fish and five of birds, which correspond to 52 different individuals and 22 taxonomic groups (tab. 2). among them, 15.9% were identified nent teeth with any or moderate wear); s (old adult or senile very advanced wear on most of the crown). the type of cortical tissue (compact in adults or more porous in young animals) was also used on the isolated diaphysis fragments. to determine the effects of biostratinomical (both hominins and carnivores) and postdepositional processes, breakage type and surface modification were treated at both macroscopic and microscopic level. when necessary, microscopic analyses of bone surfaces were carried out using a leica s6d greenough stereomicroscope with 0.75-70x magnification range, also employed for capturing images. for each faunal remain, we systematically recorded the different taphonomic alterations, including those made by rodents, carnivores or hominins, as well as climatic and edaphic modifications (water abrasion, concretion, root marking, trampling, chemical corrosion and manganese oxide coating. for the purpose of identifying these main taphonomical modifications we used the criteria established by behrensmeyer (1978), binford (1981), lyman (1994), blumenschine et al., (1996), fernández-jalvo & andrews (2003, 2016) (among others). trampling marks were distinguished from butchering marks using the works of blasco et al. (2008) and domínguez-rodrigo et al. (2009). evidence of anthropogenic modification observed on the faunal remains includes cut-marks, intentional bone breakage and burning. cut-marks have been recognised and grouped into incisions and scraping marks (binford, 1981; potts & shipman, 1981; shipman, 1981; shipman & rose, 1984; lyman, 2008; galán et al., 2009; vettese, 2014). the analysis of cut-marks took into account the number of striations, their location and distribution (isolated, clustered, crossed) and orientation (longitudinal, transverse and oblique) on the bone. by using these cut-marks criteria, it was possible to interpret the specific butchering activities (binford, 1981; fisher, 1995; nilssen, 2000). the causes of fractures were investigated analysing the type and the angle of fracturing (fresh-green or old-dry) (villa & mahieu, 1991) together with structural and surface damage, such as percussion notches, pits, impact flakes and adhering flakes (blumenschine & selvaggio, 1988; capaldo & blumenschine, 1994; pickering & egeland, 2006; galán et al., 2009; pickering et al., 2013; vettese et al., 2017, 2020). impact flakes have been defined and distin 217 late neanderthal subsistence from zooarchaeology at san bernardino cave fig. 2 above: today’s entrance of the cave after the restoration. below: stratigraphic section. unit ii visible on the section is a remnant of the layer extended over the cave entrance and completely excavated during the 1959-1964 and 1985-1993 fieldworks. 218 terlato g. et al. tab. 2 total number of skeletal remains (nr), number of identified specimens (nisp) and minimum number of individual (mni) found in san bernardino ii. anatomically and taxonomically. 84.1% were determined as generic mammals and sorted into weight size classes (tab. 2). a considerable amount of remains (nr=5,030, 53.3%) results to be indeterminate anatomically, taxonomically and by weight size class. five mammal orders including perissodactyla, artiodactyla, carnivora, lagomorpha, rodentia have been identified. ungulates (80.5% of nisp) are the most numerous one, represented by stephanorinus sp., megaloceros giganteus, alces alces, cervus elaphus, capreolus capreolus, bos primigenius, capra ibex, rupicapra rupicapra and sus scrofa. carnivores remains (nisp=235, 15.6%) correspond to ursus arctos, ursus spelaeus, canis lupus, vulpes vulpes, panthera pardus, lynx lynx, felis silvestris, mustela putorius, martes sp. lagomorphs and rodents (nisp=50, 3.3%) are represented by lepus sp., marmota marmota and castor fiber (tab. 2). these data confirm previous results obtained by cassoli & tagliacozzo (1994). due to the high fragmentation and the massive presence of diaphysis, it was challenging to precisely distinguish amongst the genera bos and bison and the species alces alces and megaloceros giganteus. for this reason, most of the remains were generically assigned to the category bos/ bison sp. and in a broad group of medium/large cervidae, which is also the case for many other contemporaneous sites. according to the nisp and mni data, the faunal assemblage is clearly dominated by cervids with capreolus capreolus and cervus elaphus as the most representative. since the roe deer represents most of the identified remains (nisp=253), it is not surprising that non identifiable bone remains assigned to medium sized animals are also the most abundant (nr=1,937, 20.5%) (tab. 2). the estimation of the age at death of 219 late neanderthal subsistence from zooarchaeology at san bernardino cave tab. 3 number of mammals remains showing butchering marks, thermal-alterations and carnivore marks. cm: cut-marks; pm: percussion marks; cm+pm: cut-marks + percussion marks; % bm: % butchering marks; ret.: retouchers; b: burned-black/brown bones; c: calcined-grey/white bones; car.: carnivore marks. the ungulates indicates a predominance of adult individuals (mni=19, 63.3%), followed by juveniles (mni=5, 16.6%) and old individuals (mni=4, 13.3%) (tab. 2). based on the analysis of dental eruption and replacement sequences, it was possible to estimate the season of death of young individuals; no foetal remains were preserved. this involves two roe deer and one wild boar. for capreolus capreolus one germen of m2 (erupt around 6-8 months habermehl, 1961) allows us to define the season of death during the end of autumn. on the other hand, two decidual premolar (one dp3 and one dp2) with marked wear attest that one individual died in spring. in the same way, seasonality indicates that the wild boar died in autumn. we identified a variety of species among the carnivore remains (tab. 2). ursids are the most abundant, while ursus spelaeus (nisp=101) is better represented than ursus arctos (nisp=3). for a total of 100 remains (ursus sp.), mostly fragments of isolated teeth and extremities of limb bones, it was not possible to precisely ascribe their taxonomy to either ursus arctos or ursus spelaeus. cave bear is represented with at least one individual for each age range, from infant to senile (tab. 2). data concerning the sex identification of animal remains are scarce, due to the high fragmentation that limited the presence of sexual diagnostic elements and the acquisition of characteristic biometric data. despite a general lack of diagnostic skeletal part, a few observations can be made. the presence of two antler fragments of roe deer suggests at least that one male is present in the assemblage. we applied the criteria proposed by d’errico & vanhaeren (2002) to three upper canines of cervus elaphus to distinguish the age and sex. however, due to the high fragmentation of remains it was not possible to determine the sex. finally, the presence of a bear’s baculum shows that one male individual is present. 4.2. general taphonomic observations assemblage from san bernardino cave is highly fragmented (98.1%). complete elements are extremely rare (1.9% of the whole assemblage is complete) and they mostly correspond to isolated teeth (16.8%) and small fat bearing bones (70.6%) such as carpals, tarsals, sesamoids and phalanges. low-density bone por 220 terlato g. et al. fig. 3 position and details of anthropogenic traces: (a) right ulna of castor fiber with skinning marks; (b) right mandible of megaloceros giganteus with cut-marks on the medial side; (c) metatarsal of alces alces with scraping marks; (d and e) femur diaphysis of cervids with scraping marks and close-up of the area used as a retoucher; (f) isolated flakes produced by percussion activity. genic breakage (tab. 3). these are mainly percussion notches and impact flakes, whereas percussion pits are rare and peeling was not recorded. we identified only one adhering flake on a giant deer bone. the damaged elements are mainly the long bones of generic ungulates and red deer. within the indeterminate bone assemblage, percussion marked remains are mostly observed on largeand mediumsized animals. the distribution, orientation and types of cut-marks (cm) provide evidence of different butchering activities. the most common types of cut-marks were incisions indicating skinning, disarticulation, defleshing and periosteum removal. in addition, scraping marks related to periosteum removal were also identified. the taxonomic groups showing cut-marks are beaver, bears and all the main ungulate species, accounting for 4.1% (nr=62) of the total nisp. three bones of castor fiber bear cut-marks (fig. 3a); romandini et al., 2018b). one right ulna shows three longitudinal incisions suggesting possible skinning (fig. 3a). clustered, short, and oblique incisions on iii and v metatarsals could be related to the removal of tendons of the hindlimb and the recovering of the hide. amongst carnivores, only ursus spelaeus and ursus sp. present remains with anthropogenic modifications. butchering traces have been observed on two portions of fibula and one portion of femur and could be related to defleshing and disarticulation. all the main ungulate species have been processed (tab. tions (ribs, sternum, vertebra fragments, scapula) and teeth are scarce (4.7% and 4.8%) and related to long-shaft fragments, which play a significant role altogether (38.5%). epiphyses are underrepresented (1.3%), and spongy bone fragments (<1%) are also scarce. ungulates remains are complete in only 7% of cases. crania, mandibles and long bones are always fragmented. the fractures analysis shows that long bones of over 3 cm mostly were broken when green, and especially by oblique, curved and smooth fractures. 28.9% of carnivore remains are complete. all the complete elements, namely teeth, metacarpals, metatarsals, and phalanges belong to bears, red fox and lynx. lagomorpha and rodentia remains are complete in 36% of cases, mostly represented by metatarsals and phalanges of beaver and marmot. overall, we observed an excellent preservation of the bone surface. among the biostratinomic modifications, we identified trampling abrasion (14.9%), root marks (9.7%), and micro-fissures from weathering and/or weathering cracks (1.9% of the total). 83% of the bones displays diagenetic alterations and manganese dendrites, while some remains show concretion (2.9%) and rare chemical corrosion (0.2%). rodents gnawing marks were detected only on 0.2% of the bones. carnivore modifications are extremely scarce and only affect 0.6% (nr=58) of the specimens (tab. 3). pits, scores and gnawing tooth marks on the diaphysis of large-sized animals are the main alterations. no corrosion attacks made by carnivore digestion were detected. only one cave bear bone shows furrowing traces that could be related to canids activity in terms of taxa, bear bones recorded the highest rate of tooth marks (22.4%), followed by chamois (8.6%). the frequency of remains with carnivore marks by weight class shows that medium-large and large sized animals were the most affected (17.2%; 10.3%). carnivore marks were observed only on few medium animals’ remains (nr=3). 4.3. anthropogenic modifications anthropogenic modifications observed in the sample include several butchering traces, bone breakage, cut-marks (1.7% of nr) and burn damage (57.7% of nr) (tab. 3). 83 remains (50.6% of nr with human traces) present percussion marks (pm) from intentional anthropo 221 late neanderthal subsistence from zooarchaeology at san bernardino cave fig. 4 frequency of skeletal elements of cervus elaphus and capreolus capreolus and distribution of anthropogenic modifications. 222 terlato g. et al. 3; fig. 3) and provide the best record for inferring human subsistence at san bernardino unit ii. anthropogenic traces were found mostly on cervids, but also on large bovids (terlato et al., 2019), caprids and wild boar remains. cut-marks are preserved on three bones of megaloceros giganteus. one hemi-mandible fragment bears longitudinal and oblique incisions. these are located on the medial side, under the second and third molars, and could be associated with the dismembering or removal of the tongue (fig. 3b). incisions aiming to meat procurement, together with percussion notches and adhering flake were recognized on one tibia. finally, one radius/ulna shows long and longitudinal incisions which might be related to defleshing. evidence of alces alces skinning is suggested by one metatarsal fragment, which also present scraping marks for periosteum removal and percussion notch for marrow extraction (fig. 3c). rupicapra rupicapra remains include one metatarsal fragment with skinning marks and one tibia shaft fragment with short, repeated, and oblique incisions that might hint at defleshing. only one first phalanx of sus scrofa yields cut-marks. cervus elaphus and capreolus capreolus are the taxa bearing most of the neanderthal induced modifications. despite the non-homogeneous presence of their skeletal parts, the exploitation of these animals is attested for all the anatomical elements in the assemblage (fig. 4). traces of human activities ascribed to dietary and non-nutritional purposes can be observed over all the anatomical parts. for cervus elaphus, 17 remains are characterized by butchering traces (tab. 3, fig. 4). each long bone of the limbs shows cut-marks, with the forelimbs (humerus, radius and metacarpal) being more intensely subjected to these human modifications, whereas only the first and the second phalanges of the extremities of the limbs present traces of this kind of alterations. cut-marks suggest defleshing (long, sparse, oblique and longitudinal incisions and scrapings, fig. 5a, c) and the cutting off of insertions of muscles and tendon (short, repeated, transfig. 5 position and details of anthropogenic modifications on some skeletal elements of cervus elaphus: (a) left radius/ulna with incisions marks and pits produced during knapping on diaphysis; (b) right femur with close-up of different cut-marks; (c) left metapodial with scraping marks. 223 late neanderthal subsistence from zooarchaeology at san bernardino cave verse and/or slightly oblique incisions, fig. 5b). both these actions mostly affected the diaphysis of the long bones. skinning (longitudinal, oblique, isolated and/or clustered) is equally well documented on the phalanges (first and second). often, different anthropogenic modifications can be observed on the same bone. for instance, one radius/ulna of cervus elaphus shows cutmarks related to defleshing and scraping aimed to the removal of the periosteum, before the bone was used for retouching (fig. 5a). concerning capreolus capreolus remains, cutmarks have been recorded on 8 bones (tab. 3, figs. 4 and 6) and they are gathered mainly on the extremities of the hindlimb: 4 metatarsal, 2 phalanges and 1 tibia. cut-marks on the metatarsal and phalanges are associated with skinning (fig. 6). the latter is also suggested by oblique cut-marks on buccal surface of one mandible. one tibia fragment bears short and transverse incision ascribed to filleting. for both species intentional bone breakage is attested by a series of percussion marks, including notch marks and percussion pits. following the analysis of percussion marks, we can observe that marrow access activity is more intense in red deer limbs. however, it is noteworthy that not only long bones were broken but even phalanges (both first and second) were exploited to get access to the marrow. deliberate fragmentation has been inferred on five phalanges of cervus elaphus and on three of capreolus capreolus. in most of them, we observed longitudinal breakage pattern as well. modifications caused by fire concerned more than half of the total specimens (57.7%): 50.6% were affected by moderate combustion (brown/black), while 7.1% were calcinated (grey/white) (tab. 3). the burnt specimens account for 21.5% of nisp and include elements from all anatomical regions and ungulate categories. roe deer is the most affected taxon by burn damage (35.1% of roe deer nisp), followed by red deer (24.4% of red deer nisp). in both cases, burnt autopodium elements outnumber other anatomical elements (fig. 4). finally, within the whole assemblage, twelve bone shafts were used as hammers for retouching flint artifacts. the retouchers were manufactured from metapodials, radius, femurs and tibia. most of them show traces of cut-marks and they belonged to large-sized herbivores, likely medium/large cervids (figs. 3d, 3e, 4 and 5a; terlato et al., 2019). 4.4. skeletal part representation of cervus elaphus and capreolus capreolus carcass transport strategy was only inferred for cervus elaphus and capreolus capreolus, as they yielded the most abundant data (tab. 4, fig. 7). %mau shows a clear predominance of the limbs over the axial skeleton elements (tab. 4). the anatomical distribution is characterized by a significant presence of phalanges and sesamoids followed by frontal and hind limbs bones (humerus, radius/ulna, metacarpals, femur, tibia and metatarsals). cranium is mainly represented by isolated teeth and fragmented parts of the mandible, maxilla and antler. the axial skeleton is almost absent, with only one portion of red deer’s rib. the two species do not present any considerable difference between forelimbs and hindlimbs representation. conversely, some dissimilarities can be detected in terms of nisp between the limb bones, among which metacarpals and metatarsals are fig. 6 position and details of anthropogenic modifications on some skeletal elements of capreolus capreolus: a-b) metatarsal with longitudinal cut-marks; (c) left second phalange with close-up of skinning incision. 224 terlato g. et al. tab. 4 nisp (number of identified specimens), mne (minimum number of elements), mau and %mau (minimum animal unit) of cervus elaphus and capreolus capreolus. 225 late neanderthal subsistence from zooarchaeology at san bernardino cave fig. 7 percentage of minimum anatomical units of cervus elaphus and capreolus capreolus tab. 5 correlation between %mau and mgui (modified general utility index), fui (food utility index), cfui (corrected food utility index), umi (unsaturated marrow index), grease, meat, marrow and bone density indices of cervus elaphus and capreolus capreolus. 226 terlato g. et al. always the most represented elements (tab. 4). the results of the differential transport strategies adopted by neanderthal groups for cervus elaphus and capreolus capreolus are presented in tab. 5. considering red deer, the bivariate correlations between %mau with mgui, fui and cfui are negative (ρ=-0.03, ρ=0.15, ρ=-0.06) and not significant (p=0.88, p=0.54, p=0.81). with regard to roe deer, the correlation between %mau with mgui is negative (ρ=-0.29) and not significant (p=0.17); with the food utility indexes (both fui and cfui) the correlations are positive (ρ=0.11 and ρ=0.15) and not significant (p=0.65 and p=0.54). %mau and meat index is negative for both cervids (ρ=-0.23 and ρ=-0.53), however it is not-significant for red deer (p=0.29) and significant for roe deer (p=0.01). for both species, %mau with grease, marrow and umi indexes are positively (ρ=0.47, ρ=0.67, ρ=0.81 ρ=0.41, ρ=0.61, ρ=0.31 respectively) and significantly correlated (p<0.05), except for roe deer’s umi that is not significantly correlated (p>0.05). %mau with bone density is positively and significantly correlated for both species (ρ=0.55, ρ=0.45 and p=<0.05). finally, no significant correlations were found between the bone density and utility indexes for both species. transport decision privileged anatomical parts rich in grease and marrow (mainly long bones, including metacarpals and metatarsals) to exploit them at the site (fig. 8). the results of the bayesian model for the evaluation of the prey transport strategies (α) are 0.33 and 0.35 for cervus elaphus and for capreolus capreolus, and the attrition at the assemblage (β) (fig. 9, tab. 6) are 6.43 and 6.34, respectively. these data indicate carrying prey strategy for both taxa of the appendicular skeleton (α median values) and very high attrition at the level (β median values). the β median index with values of 6, implies that more than 95% of the original record would have disappeared (tab. 6). the high attrition would explain the imperceptible representation of low dense elements. the results of correspondence analysis, in addition to a significant level of attrition, attest a greater degree of appendicular skeleton processing for both species. fig. 8 correlation between % mau and marrow index of cervus elaphus and capreolus capreolus. tab. 6 alpha parameter (skeletal transport) and beta parameter (attrition) of cervus elaphus and capreolus capreouls, and interpretation of the bayesian model. and the few remains of fishes and birds (ducks and geese) (cassoli & tagliacozzo, 1994; fiore et al., 2004) suggest humid environments and watercourses in the proximity of the site. finally, the importance of castor fiber remains is given by the peculiar environmental conditions it lives in, always associated with flowing water. these data are consistent with a recent study of the micromammal associations, which highlights the 5. discussion the zooarchaeological data acquired through our analysis allow the reconstruction of neanderthal subsistence economy and ecological exploitation during the first half of mis 3 at san bernardino cave. the taxonomic consistency of the faunal remains, dominated by the ungulates, especially cervids, as well as the taphonomic bone modifications and its association with lithic tools (peresani, 1996), support the anthropic origin of the assemblage, occasionally disturbed by biological agents other than humans. 5.1. palaeoenvironmental implications from macromammals the faunal spectrum shows the presence of a broad variety of species, mostly represented by ungulates such as large bovids, large and medium-sized cervids, caprids, and wild boar, but also some carnivores, leporids and rodentia, associated with scant remains of fish and birds. regarding the ecological context, the faunal assemblage from san bernardino ii is representative of diverse past environments inhabited by humans. in fact, the site surroundings consisted of close and open forests with transitive and discontinuous alpine grasslands or sparse vegetation on carbonate rocks, completed by a humid environment and watercourses. the dominance of red deer and roe deer over other taxa may reflect that forests were commonly the neanderthals’ most exploited hunting environment. however, caution is needed in declaring this assumption given the ecological plasticity of these kind of deers, which can live in different ecosystems. the roe deer primary habitat is forest clearings, hedges, and woodland edge (danilkin, 1996). furthermore, red deer can inhabit variable environments, from open steppe to close temperate forest (geist, 1999). besides, the wild boar remains reveal the existence of woodlands close to san bernadino cave. moreover, the exploitation of large bovids is representative of ecological conditions diversity, spanning from dense forests with wetlands and small streams ecologically, more attractive to bos primigenius, to hilly grasslands and plains populated by bison (terlato et al., 2019). still, rhinoceros, moose, beaver 227 late neanderthal subsistence from zooarchaeology at san bernardino cave fig. 9 α and β parameters from cervus elaphus and capreolus capreolus 228 terlato g. et al. presence of microtus agrestis and apodemus gr. sylvaticus-flavicollis as the most abundant species in unit ii, thus demonstrating mild and humid conditions in a landscape dominated by woodland formations (lópezgarcìa et al., 2017). 5.2. subsistence economy it must be mentioned that, despite the varied environmental range that existed around the cave, which were the habitat of the prey species, the inhabitants of the site may not had spent equal time foraging in these different patches. taxonomic data demonstrate that the majority of mammals remains carried to the site belonged to prey typical of woodlands, valley bottoms and lowlands. the paucity of large prey types within the assemblage, might be explained with a lower encounter rates than red deer and roe deer’s one, or, perhaps, they were disregarded when the hunters’ success rate were lower than the ones for smaller prey species (bird et al., 2009). on the other hand, while small/medium ungulates, like chamois and ibex, might have a higher rate of capture due to their marked attitude for living in herds compared to wild boar or roe deer’s ones for instance-, they were less frequently encountered than red deer and roe deer (marín-arroyo, 2009b; romandini et al., 2014). it is also possible that ungulates typical of rocky landscapes or highlands were in part excluded from the diet but used as an alternative food source when the higher-ranked game was less abundant. furthermore, it seems that mountain habitat areas were not widespread nearby the cave. san bernardino is not a unique example of neanderthal subsistence, as other late middle palaeolithic settlements in the fringe of sub-alpine area show similarities with it. this is the case of tagliente rockshelter (thun-hohenstein & peretto, 2005; thun-hohenstein, 2006) and fumane cave (cassoli & tagliacozzo, 1991; fiore et al., 2004; romandini et al., 2014, 2020a; peresani et al., 2017). qualitative and quantitative data reveal that the types of hunted ungulates at each site are compliant with their respective environmental and climatic conditions. at tagliente, layers 35-37, the most common species to have been brought into the site are roe deer and red deer, while ibex and chamois are less common. at fumane, units a5-a6 and a9, hunting targeted different species, primarily red deer, roe deer and large cervids of all age classes, with a lesser incidence of chamois, ibex, large bovids (peresani et al., 2011; romandini et al., 2014) and to birds (fiore et al., 2016; romandini et al., 2016). to further analyse the diet breadth in terms of diversity, we measured the inverse of simpson's index, which takes into account both richness and evenness, as shown in tab. 7. san bernardino, fumane unit a9 and tagliente share a similar pattern for hunted species. the nisp values are quite lower in relation to animal. on the other hand, mni index is higher and it identifies the diversification of species consumption. hence, this framework confirms that selective hunting was undertaken by humans in order to target game availability in the surroundings of the site. 5.3. hunting strategies and site functionality at san bernardino cave, humans were the principal agents of the faunal assemblage. occasionally, other predators scavenged neanderthals’ leftovers, as attested by the low percentage of carnivore gnawing marks found on bone surfaces. this situation suggests a secondary access to the remains for carnivores, which therefore did not significantly contribute to bone accumulation after or before human activities. hunting practices targeted different species. in particular, clear traces of anthropogenic intervention have been documented on three remains of castor fiber’s bones, related to fur recovering (romandini et al., 2018b). nevertheless, cave bear is the only carnivore species presenting few remains with anthropogenic modifications. infant or very young and senile cave bears show a differentiated occupation of the cave by humans and bears, as also recorded in late middle paleolithic sites in northern italy, such as fumane cave, rio secco cave among others (romandini et al., 2018a). as a matter of fact, ungulates were the most exploited animals. cervids, mostly deer and roe deer adult specimens, were the most hunted animals. yet, the presence of two young, one sub-adult, four adult and two senile individuals of c. capreolus reflects the age structure of natural populations, thus confirming the hypothesis for the exploitation of whole herds. seasonality information inferred by roe deer hunting season, allowed to esteem that the site occupation likely occurred during summer and autumn. on the other hand, the absence of fetal and neonatal individuals suggests that the site was not frequented in spring. nevertheless, seasonality studies are still lacking a more complete documentation. for this reason, the acquisition of more detailed data based on isotopes, microwear analysis and cemento chronology is needed to provide further information. the neanderthals used san bernardino as a place where, after an initial preparation at the kill-site, carcasses processing and consumption activities were carried out; still, discarded bones were used for lithic manufacturing. this is revealed by the skeletal profile analyses achieved with the correlation indices and the bayesian method for cervus elaphus and capreolus capreolus. as a matter of fact, it seems that neanderthal groups carried to the site appendicular body parts, by selecting the anatomical parts with higher nutritional content (both marrow and meat) and economic values, even for roe deer with a smaller body size than red deer. hence, the high significant statistical correlations between %mau and grease, marrow and umi likely identifies a preference for bones transportation related to their grease and marrow content, except for roe deer, for which no statistab. 7 san bernardino, fumane and tagliente ungulates diversity results based on the inverse of simpson’s index (1/d) according to nisp values. adata from romandini et al., 2014; bdata from thun-hohenstein 2006. 229 late neanderthal subsistence from zooarchaeology at san bernardino cave tical correlation with unsaturated marrow index (umi) was detected. cut-marks, scraping, burning, percussion marks and fresh fractures are present, without any significant difference in both animals. moreover, the correlation between the fracture degree and the marrow index has confirmed the intense exploitation of within-bone nutrients, even in the case of phalanges. in fact, phalanges exploitation for marrow extraction is due to its taste and soft texture. the marrow present in the phalanges is known for its better taste because of its high content of unsaturated fatty acids, compared to other long bones (morin, 2007). we demonstrated that the extremely high attrition of the bones in this cave could be related to the selective transport of the prey and to the intensive human activity. the latter consisted in the abovementioned process and the employ of butchering refuse, rich in fats, used as fuel for fires or living floor maintenance (costamagno et al., 2009, 2010; morin, 2010). the absence of vertebrae and ribs, together with other low-survival elements could also be due to such reasons (marín et al., 2017). considering the differential carcass transport, even though a considerable attrition within the assemblage affected less dense skeletal elements, it might be inferred that neanderthal groups maximized the caloric input of the hunted prey brought to the cave. such decisions might depend on several factors, including the weight of both red deer and roe deer carcass portions, the distance between the kill/prime butchering site and the camp base, the daytime of the hunting episode, the number of hunters involved, and so on (mnahan, 1998; marín-arroyo, 2009a; schoville & otárola-castillo, 2014). moreover, the number of hunted animals and the competition with other carnivores in the environment, must not be excluded either. san bernardino cave’s topographic location low altitude, close to the edge of a karstic plateau dissected by deep valleys and delimited by the alluvial lowlands supported the exploitation of the prey recognized. at the same time, its position required significative efforts to cover distance in the landscape. likely, carrying patterns of red deer and roe deer did not exceed 5-7 km from the site, underpinning an intentional focus on local resources. additionally, knappable raw materials for stone tools were available in the surroundings. nevertheless, large bovids’ remains and the presence of exogenous raw materials also suggest that longerdistance movements did occur (peresani, 1996). 6. conclusion zooarchaeology and taphonomic analyses, thanks to their capability of characterising human economic behaviour and its relationship between human-animal and environmental exploitation, is currently one of the most widely used approaches to understand human strategies. macrofaunal data from san bernardino cave provide new insights regarding animal exploitation and butchering practices during the late middle palaeolithic in continental italy. the faunal spectrum reveals that site occupation generally occurred with temperate conditions, suggesting a forest landscape interspersed with clearings and wetlands. still, our results have shown that, despite the high attrition of the assemblage, neanderthal subsistence strategies at san bernardino cave were mostly based on ungulates exploitation, especially red deer and roe deer, whereas the procurement of large ungulate and small chamois was sporadic. neanderthal groups adopted a notable degree of energetic efficiency in carcasses processing, with a quite selective transport of red deer and roe deer. all this evidence highlights additional aspects of neanderthal landscape use, hunting strategies and mobility in north-eastern italy, where eastern italian alps’ ecosystems and forelands offered a wide range of opportunities in terms of animal resources, to sustain neanderthal populations approaching the edge of their demise. acknowledgements excavations and studies at san bernardino cave are coordinated by the university of ferrara (m.p.) and supported by the ministry of cultural affairs and tourism and veneto archaeological superintendency (sabapverona, vicenza and rovigo), public institutions (veneto region department for cultural heritage, province of vicenza, municipality of mossano). author contributions: m.p. conceived research; v.l., g.t. and m.r. analysed data; a.b.m.a. supported new radiocarbon dating; s.b. and m.r. are supported by the erc-cog horizon 2020 project success (ref 724046 website: http://www.erc -success.eu/); g.t. and m.p. wrote the paper with inputs from a.b.m.a., m.r. and s.b. the authors want to acknowledge lucía agudo pérez for graphic support. radiocarbon dating has been funded by the erc-cog horizon 2020 project subsilience (ref 818299 website: https://www.subsilience.eu/) led by a. b. marínarroyo. references aitken r.j. 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(2020) last interglacial iberian neandertals as fisher-hunter-gatherers. science, 367(6485), eaaz7943. ms. received: march 2, 2021 revised: april 30, 2021 accepted: may 5, 2021 avaiable online: june 29, 2021 236 base multi-proxy reconstruction of late pleistocene to holocene paleoenvironmental changes in sw calabria (southern italy) from marine and continental records maria pia bernasconi1, francesco l. chiocci2, salvatore critelli1, mauro f. la russa1, stefania marozzo1, eleonora martorelli2, elena natali3, teresa pelle1, gaetano robustelli1, elda russo ermolli4, fabio scarciglia1 & vincenzo tinè3 1 dipartimento di scienze della terra, università della calabria, arcavacata di rende (cs) 2 dipartimento di scienze della terra, università “sapienza”, roma 3 soprintendenza speciale al museo nazionale preistorico etnografico “l. pigorini”, roma 4 dipartimento di arboricoltura, botanica e patologia vegetale, università di napoli “federico ii”, portici (na) corresponding author: f. scarciglia <scarciglia@unical.it> abstract: bernasconi m.p. et al., multi-proxy reconstruction of late pleistocene to holocene paleoenvironmental changes in sw calabria (southern italy) from marine and continental records. (it issn 0394-3356, 2010). in this work we reconstructed the major climatic changes occurred since the last postglacial transition to the holocene in sw calabria (southern italy). we applied a multidisciplinary approach based on both marine and continental paleoclimatic and paleoenvironmental proxies. in particular, we focused (i) on the effects of eustatic sea-level rise on the submerged continental shelf (interpreted through offshore seismic and core stratigraphy, along with paleoecological and palynological analyses), and (ii) on the geomorphic consequences on land of the main climatic changes and their interplay with late prehistoric to historic human activities (deforestation, cultivation, ploughing, etc.), recorded by soil features in archaeological contexts and pollens in marine cores. in particular, the transgressive and highstand systems tracts that overly the last glacial maximum unconformity surface were reconstructed in detail. they indicate an upward deepening of sedimentary environments followed by overall depth stability, also confirmed by mollusc paleobiocoenoses. geomorphic stability coupled with warm and humid climate characterized the middle holocene, promoting major soil development during neolithic times. important changes in soil features towards the late holocene point to a phase of climatic drying and land degradation (probably during the bronze age, ~4 ka bp), followed by restored prolonged moisture availability alternated with minor warm or dry events. different episodes of intense soil erosion and human impact occurred in this period, with increasing deforestation and cultivation during about the last 2 ka, as testified by soil features and pollen stratigraphy. the consequent marine response can be probably related to seaward progradation of the late holocene sedimentary units, also reflecting river systems adjustment to eustatic base-level rise and highstand. riassunto: bernasconi m.p. et al., ricostruzione multi-proxy delle variazioni paleoambientali dal tardo pleistocene all’olocene in calabria sud-occidentale (italia meridionale) attraverso record marini e continentali. (it issn 0394-3356, 2010). in questo lavoro sono state ricostruite le principali variazioni climatiche avvenute dall’ultima transizione postglaciale all’olocene in calabria sud-occidentale (italia meridionale). è stato applicato un approccio metodologico multidisciplinare basato su indicatori paleoclimatici e paleoambientali sia marini sia continentali. particolare attenzione è stata rivolta (i) agli effetti della risalita eustatica del livello del mare sulla piattaforma continentale sommersa (interpretati attraverso stratigrafia sismica e di carote di sondaggio a mare, unitamente ad analisi paleoecologiche e palinologiche), ed (ii) alla risposta a terra dei processi geomorfici ai principali cambiamenti climatici ed alla loro interazione con le attività antropiche tardo-preistoriche e storiche (deforestazione, coltivazione, aratura, ecc.), registrate nei caratteri pedogenetici dei suoli in contesti archeologici e nei pollini in carote marine. in particolare, sono stati ricostruiti in dettaglio i sistemi trasgressivi e di stazionamento alto sovrastanti la discordanza angolare dell’ultimo massimo glaciale. essi indicano un approfondimento verso l’alto degli ambienti sedimentari, seguito da una generale stabilità della profondità, anche confermati dalle paleobiocenosi a molluschi. condizioni di stabilità geomorfologica e clima caldo-umido hanno caratterizzato l’olocene medio, promuovendo un importante sviluppo del suolo durante il neolitico. rilevanti modificazioni nei caratteri pedogenetici verso l’olocene superiore indicano una fase di inaridimento climatico e di degradazione del suolo (probabilmente avvenuta durante l’età del bronzo, ~4000 anni fa), seguita da un ripristino di condizioni di prolungata umidità, alternata ad episodi minori caldi o aridi. in questo periodo avvengono diverse fasi di intensa erosione del suolo ed impatto antropico, con un incremento della deforestazione e delle coltivazioni grossomodo negli ultimi 2000 anni, come testimoniato dai caratteri dei suoli e dalla stratigrafia pollinica. la conseguente risposta in ambiente di piattaforma può probabilmente essere messa in relazione con la progradazione verso mare delle unità deposizionali tardo-oloceniche, che riflettono anche il riequilibrio dei sistemi fluviali in funzione della risalita eustatica e dello stazionamento alto del livello di base. keywords: seismic and core stratigraphy; paleoecological reconstruction; mollusc; pollen analysis; soil development; late pleistocene to holocene climatic changes; deforestation parole chiave: stratigrafia sismica e di sondaggio; ricostruzione paleoecologica; molluschi; pollini; sviluppo pedogenetico; variazioni climatiche del tardo pleistocene – olocene; deforestazione il quaternario italian journal of quaternary sciences 23(2), 2010 263-270 introduction this paper reports the results of a multidisciplinary study that integrates a wide variety of continental and marine geological and morphostratigraphic data along the tyrrhenian sea margin of calabria, in southern italy. most of the existing literature concerns methods and data that deal with onshore and offshore environments, separately. very little is known about correlations between continental and marine stratigraphic records in the light of morpho-evolutionary reconstructions, i.e. in terms of submerged sedimentary 264 p.m. bernasconi et al. environment responses to geomorphic processes in adjacent onshore catchments. only few papers make such an attempt in the calabria region, focusing on modern sediment composition and provenance, role of eustatic versus tectonic base-level changes on sedimentary/erosive phases during the quaternary, relationships among sea-floor morphologies, seismicity and mass wasting phenomena (le pera & critelli, 1997; le pera et al., 2000; robustelli et al., 2005; rebesco et al., 2009; martorelli et al., 2010). in particular, le pera & critelli (1997) evidence a strict relationship among modern petrofacies of the main river/stream drainage catchments, coastal beaches and marine environments along the northern-central sector of western calabria. they show that marine sediment composition mainly reflects feeding sources from metamorphic and plutono-metamorphic rocks of the coastal range, sila massif and monte poro inland relieves, which can be expected to have controlled also past depositional environments. also the role of river systems interacting with postglacial sea-level rise and marine seismic stratigraphy is explored by martorelli et al. (2010). moreover, robustelli et al. (2005) evidence the interplay between tectonically-induced trenching of alluvial fans debouching from the mountain front of the coastal range and paleovalleys dissected onto the emerged continental shelf during the last glacial sea-level lowering, as pathways for seaward sediment delivery. conversely, they indicate major phases of alluvial fan aggradation during interglacial sea-level rise, possibly coupled with tectonic subsidence, that created suited accommodation space. the role of quaternary climatic changes on sediment production and delivery was also highlighted. in this framework we applied an integrated multidisciplinary approach to characterize the main environmental changes occurred both on the continental shelf and inland during the late pleistocene postglacial transition and the holocene, using different proxies and methods (stratigraphy, palaeontology, palynology, geomorphology, geoarchaeology and pedology). we aimed at a multiproxy interpretation of climatically-driven changes in the main geomorphic processes, trying to correlate data from different morphostratigraphic contexts. moreover, we focused on an attempt to discriminate natural from anthropogenic-induced signals. data and discussion the main climatic and environmental changes since the last glacial maximum through the holocene were reconstructed on the basis of offshore boreholes and seismostratigraphic data in the continental shelf located offshore the paola-briatico sector (along the eastern edge of the coastal range and the s. eufemia plain), a borehole along the present coastline near briatico and onshore pedostratigraphic successions from an archaeological site in the surroundings of palmi (at the southern end of the gioia tauro plain) and from the monte poro plateau, which borders the same plain to the north (fig. 1a). this sector of calabria consists of alternating morphotectonic highs and tectonic depressions, bordered by ne-sw and wnw-ese-trending fault systems (e.g. catalano et al., 2008). the coastal zone preserves a typical sequence of stair-like marine terraces, which testify high uplift rates (miyauchi et al., 1994; balescu et al., 1997; tortorici et al., 2003). the main paleoenvironmental changes occurred in the continental shelf during the considered time span, were reconstructed using seismostratigraphic interpretation and core stratigraphy. the stratigraphic analysis was integrated with paleoecological data obtained from mollusc fossil assemblages and pollen analyses (the latter only performed on clayey deposits). marine deposits show variable characteristics, pattern of depocenter depths and thickness, which indicate significant changes in sedimentation rates, related to differential sedimentary input, accommodation space and tectonic behavior (as also evidenced along northern sectors of the tyrrhenian sea; chiocci et al., 1989; argnani & trincardi, 1993; carboni et al., 2005; martorelli et al., 2010). on the continental shelf, the seismostratigraphic architecture of the shallow subsurface is described by martorelli (2000) and martorelli et al. (2010). it is characterized by a well developed postglacial depositional sequence (pds), lying on a regional erosional unconformity, i.e. the last glacial maximum unconformity (lgm-u), with a maximum age of about 20,000 years bp. the lgm-u is outlined by a high-amplitude reflector which truncates the underlying plio-pleistocene prograding units (fig. 1b). the pds is an incomplete and still evolving depositional sequence made up of both the transgressive systems tract (tst) and the highstand systems tract (hst). the deposits of the pds occur on almost all the continental shelf reaching a notable thickness (up to 65 m) on the inner sector. the tst consists of up to 3 parasequences with a retrogradational stacking pattern, that are laterally confined by the irregularities of the lgm-u. tst deposits are characterized by a number of isolated depocentres. the hst is made up of two parasequences, arranged in a progradational and aggradational stacking pattern. these parasequences are probably of holocene age and are bounded by a non-depositional surface. the lower parasequence lies directly on the maximum flooding surface (mfs) and shows a constant low-amplitude acoustic facies throughout the area. it is generally prograding and the reflectors become concordant with respect to the mfs only on the outer shelf. the upper parasequence shows a variable acoustic facies, especially in its upper part, which varies from a completely transparent facies to a high continuity-high amplitude seismic facies. the distribution of the hst deposits is rather regular with an almost continuous wedge over the entire area. the thickness of hst deposits is maximum (50 ms t.w.t., around 40 m) offshore of the savuto river, the larger fluvial catchment in the study area dissecting the coastal range, north of the s. eufemia plain, and diminishes rapidly seaward. there, the relatively thick (~15 m) upper parasequence is characterized by discontinuous high-amplitude internal reflectors, which may indicate coarser lithologies linked to its river delta. slope breaks, in places revealing terraced surfaces and/or bioherms, that probably represent sea-level stillstands, can be identified at about 3-4 km from the present coastline across the lgm erosional surface. moreover, the latter is incised by deep paleovalleys, some of which developed during exposure of the shelf as a response to glacial sea-level lowering, and subsequently filled and sealed by the holocene sedimentary wedge. well developed transgressive deposits (up to tens of meters thick) made of nearshore sands and gravels, provided a detailed record of the last transgression and highstand (martorelli, 2000; martorelli et al., 2010). in order to correlate these data with those on the land sites, the closer cores collected offshore of briatico were analyzed (4a, 4arip, 6a, 6b, 6brip), ranging in length between 170 and 450 cm (fig. 1c), and compared with the top section of a nearby coastal one (bria 2). these cores clearly show part of the transgressive and highstand deposits. the age of the base of offshore cores ranges from 11326 to 9296 cal. years bp (radiocarbon dates on mollusc shells) in sand and silty sand transgressive deposits, respectively. sometimes, quite dissimilar core stratigraphy depths and/or sedimentary facies even at very short distance, suggest the occurrence of some depositional hiatuses. this feature is highlighted by some much younger radiocarbon dates (as the 2573 cal. years age in core 6a) recorded in the lower-intermediate portion of few cores, very close (~ 60 cm) to the depth of layers dated to about 10 ka. the closeness of these cores to river mouths, feeding important sedimentary input to the shelf environment, might explain the discontinuous sedimentary records. for instance, in core 6a this is also consistent with an opposite trend of sedimentological and paleobiotope data in depth (especially in the upper core section) with respect to those from the other offshore cores. this hypothesis is also supported by a prominent role of steep and high-sloping river catchments located close to the coast, which could have enhanced sediment transport and distribution onto the shelf. 265multi-proxy reconstruction of late pleistocene to ... in the offshore cores paleobiological and sedimentological evidence detect two depositional systems: from core bottom to top, it is noteworthy an upward deepening of the paleobiotope, followed by a phase characterized by a depth stability of the paleoenvironments (marozzo, 2004). molluscan assemblages are interpreted according to the meditrerranean benthic bionomy of pérès & picard (1964) and pèrès (1982). acronyms used to identify mediterranean biocoenoses are derived from their original french names and their english translation as reported in bernasconi & robba (1993). the increasing depth is marked by the replacement of infralittoral epifaunal species strictly related to the biocoenoses of posidonia seagrass (hp) and of photophilous algae (ap), such as bittium reticulatum, obtusella macilenta with those related to the circalittoral biocoenoses of coastal detritic bottoms (dc) and of terrigenous mud (vtc) (timoclea ovata, parvicardium minimum and turritella communis). the depth stability is reached when molluscan assemblages are characterized by high dominance values of kelliella abyssicola, a species strictly related to the biocoenosis of bathyal mud (vp). the transition represents the maximum flooding surface of the transgression, recorded slightly later (upward) than observed in seismostratigraphic data (fig. 1c). the onland core collected near briatico (bria 2) is 8 m in length and is still in study. in its midto upper section (0-5 m) shows, from bottom to top, marine grey clay deposits (~2.5 m thick) overlaid (up to the top) by two moderately-developed, organic-rich, dark brown soils (the lower also exhibiting some illuvial clay coatings within pores), intercalated by centimetreto decifig. 1 location map of the study sites and stratigraphic cores (a); seismic profile passing across core 4arip (b); schematic stratigraphy of selected cores (6a, 6b, 6brip, 4a, 4arip) and radiometric ages (c). see text for details. ubicazione dei siti di studio e dei sondaggi (a); profilo sismico passante dal sondaggio 4arip (b); stratigrafia schematica dei sondaggi selezionati (6a, 6b, 6brip, 4a, 4arip) ed età radiometriche (c). si veda il testo per i dettagli. 266 metre-thick, whitish caco3-concretioned layers, tentatively correlated with the soils described in the archaeological excavations, reported below. the pedostratigraphic succession excavated in the onshore site close to palmi, on a wide terrace at 500 m a.s.l., mainly consists of silt loam soils with some volcanic input and variable morphological features, which can be partly dated on the basis of in situ archaeological settlements and finds. they include well developed, dark yellowish-brown buried argillic (btb) horizons, overlaid by truncated and buried, often artificially reworked, dark brown organic-mineral (ab) horizons (fig. 2a). these layers can be ascribed to about 6500-5800 cal. years bp thanks to the occurrence of late neolithic ceramic artefacts (diana style facies) and typical incineration burials found in biconical vases. they are in turn overlaid and strongly superimposed by a widespread paleosurface related to late early bronze age colonization (about 4000-3700 cal. years bp), which shows similar features to the palma campania and capo graziano archaeological facies defined in other sites of southern italy (e.g. albore livadie, 1999). this surface is affected by many pole holes left by not preserved large wooden huts, ploughed furrows, excavated cisterns, ditches and trenches, often filled with organic-rich dark brown soil material, also filling some large pockets in argillic horizons. also hearths with charcoal remains, burials, vases and other diagnostic ceramic fragments occur. above the bronze age surface, the upper stratigraphic succession consists of brown anthropogenically disturbed organic-mineral (ap) horizons that appear cyclically ploughed during historical times (archaeologically not well dated because of their reworking for agricultural practices), in places disturbing with abrupt irregular boundaries the underlying horizons. the chronological constraints supplied by the archaeological stratigraphy are in agreement with the volcanic glass content identified at the microscopic scale in all soil horizons, using sem-eds analysis (fig. 2b). the dominant rhyolitic composition of volcanic pumices is quite similar to that analyzed in the analogous, widespread andisols (iuss working group wrb, 2006; soil survey staff, 2010) of monte poro upland and gioia tauro plain, which can be related to late pleistocene to holocene volcanic eruption/s from the aeolian islands (aramini et al., 2005; scarciglia et al., 2006). this chronological constraint is also supported by the late palaeolithic to late neolithic and late bronze age archaeological settlements and artefacts found in the volcanic soils of monte poro (pacciarelli, 2008). therefore major soil development probably occurred during most of the holocene (and maybe the late pleistocene). the above soil features, coupled with chemical, physical and mineralogical analyses, as well as micromorphological observations performed on thin sections from undisturbed soil samples (fitzpatrick, 1984), allowed us to propose the following reconstruction. a period of geomorphic stability under warm and humid climatic conditions (with high moisture availability and some seasonal contrast) characterized the latest phases of the neolithic and likely the following initial stages of the bronze age, with important soil development under a stable vegetation cover, that can be related to the upper part of the holocene climatic optimum (cf. scarciglia et al., 2009). this hypothesis is supported by the presence of clay coatings in bt horizons (quite enhanced in warm and humid climates) and by their relict significance (i.e. the present inactivity of illuvial processes) highlighted by micromorphological observations, showing that they often appear fragmented and with smooth-banded to grainy extinction patterns between crossed polars (fig. 2c) (fitzpatrick, 1984; catt, 1989). coherently, the latest phases of important clay illuviation in temperate mid-latitude and mediterranean environments are well documented just during the holocene climatic optimum (e.g. catt, 1989; scarciglia et al., 2009). the above conditions are further supported by: (i) more abundant phyllosilicate clays detected by x-ray diffractometry in argillic horizons; (ii) overall lower amounts of short-range order minerals (srom) and less developed andic properties (sensu iuss working group wrb, 2006; soil survey staff, 2010), estimated on the basis of field morphological features, ft-ir spectroscopy and the oxalateextracted al and fe index (icomand, 1988). these climatic conditions are quite consistent with the climate amelioration characterized by progressive temperature and moisture increase, documented for the lateglacial and the early-middle holocene (russo ermolli & di pasquale, 2002; carboni et al., 2005; giraudi, 2005; di donato et al., 2008), and the concurrent sea-level rise (approaching the present-day level at about 6-7 ka bp; buccheri et al., 2002; lambeck et al, 2002), also recorded in the offshore cores. this period was followed by a severe land degradation during the bronze age at about 4000 cal. years bp, also identified in many places along the italian peninsula, where a drought phase (tentatively recorded by the carbonate-concretioned layers within the brown soils in the bria 2 coastal core) presumably contributed to the effects of deforestation (e.g. di rita & magri, 2009). this phase is testified by erosion and human impact extensively affecting surface a horizons. on the other hand, it cannot be excluded a relevant role of other dry episodes during the middle-late holocene, such as those at 5.4 and 3-2.3 ka bp, likely related to the global scale rcc events of mayewski (2004) and recently identified by di donato et al. (2008) in the salerno gulf (more than 200 km far to the north). these climatic phases might have prepared and enhanced, respectively, the above land degradation. although no detailed chronological data are available for the whole postglacial depositional sequence, the occurrence of two hst parasequences, their progradational and aggradational stacking pattern, coupled with their maximum thickness offshore of the savuto river, suggest that some relevant changes occurred inland during their emplacement in terms of erosion and sediment delivery within and from the main river catchments seaward. these modifications can be related to adjustment of river systems after mere glacio-eustatic sea-level rise and highstand, possible holocene tectonic uplift (cf. pirazzoli, 2005) though not evidenced by our data, as well as to the effects of human impact in their feeding areas. in particular, the above land degradation during and after the bronze age could be tentatively correlated to progradation of the upper parasequence forming the upper part of the highstand system tract, which very likely represents the p.m. bernasconi et al. 267 late holocene stratigraphic record. we cannot rule out a simultaneous coastline progradation, because no clear morphostratigraphical records are available. nevertheless, the possible coarse-grained delta facies identified in the thick hst upper parasequence offshore of the savuto river may be associated to a late holocene coastline progradation. in addition to anthropogenic impact on land, such fluvial and shelf deposition could be likely related to a transition towards higher moisture availability in soils (subsequent to the above drought phase), which also underwent repeated, undetermined phases of ploughing throughout the late holocene. in fact, andic properties appear more developed in a horizons, where abundant short-range order aluminosilicates are associated with minor phyllosilicates (as also supported by their dominant isotropic matrix in crossed polarized light), which suggests the occurrence of a regime with prolonged (and overall seasonally poorly-contrasted) moisture availability. this phase might be at least partly related to temperate cooling events during the last 3000 years, characterized by minor warm or dry episodes, as testified by higher lake levels or burial of soils by glacial/periglacial deposits in central italy and glacier expansions in the alps (giraudi, 2005, 2007). on the other hand, the effects of soil degradation, deforestation and agricultural practices are highlighted by truncation of late prehistoric fertile a horizons, once developed at surface under particularly suited climatic conditions (the above neolithic optimum) and vegetation cover, but nowadays not completely preserved in situ. the organic-rich filling of soil pockets in the argillic horizons and more extensively of ploughing furrows and artificial excavations, likely represents the eroded material. moreover, a horizons include some reddishyellow, subrounded pedorelicts exhibiting fragments of clay coatings, probably stripped away from the underlying bt horizons by erosion or ploughing activities. also the pollen analysis evidenced a drastic change in the vegetation cover, presumably caused by this anthropogenic land degradation, which probably went on even during more recent times. an extremely severe reduction of arboreal taxa typical of the mediterranean fig. 2 soil profile in the archaeological excavation close to palmi (a): the upper dashed line represents the late early bronze age paleosurface (~4000-3700 cal. years bp) affected by clear ploughing traces, also involving younger overlying disturbed ap horizons; all the underlying soil layers, i.e. buried organic-mineral (ab) horizons and argillic (bt) horizons, date to late neolithic (~6500-5800 cal. years bp); sem image of a volcanic micropumice and associated eds spectrum from the lower ap horizon of the profile (b); microphotograph showing fragmented and smooth-banded clay coatings from horizon 2btb2 in crossed polarized light (c). profilo pedologico nello scavo archeologico vicino a palmi (a): la linea tratteggiata superiore rappresenta la paleosuperficie del tardo bronzo antico (~4000-3700 anni fa) interessata da tracce di aratura ben evidenti, che coinvolgono anche i sovrastanti orizzonti ap; tutti i livelli pedologici inferiori, cioè gli orizzonti organico-minerali sepolti (ab) ed argillici (bt), sono databili al neolitico finale (~6500-5800 anni fa); immagine al sem e relativo spettro eds di una micropomice vulcanica dall’orizzonte ap inferiore del profilo (b); microfoto mostrante pellicole d’argilla frammentate ed a bande sfumate dall’orizzonte 2btb2 in luce polarizzata incrociata (c). multi-proxy reconstruction of late pleistocene to ... 268 mesophilous forest is observed in two cores located offshore of briatico, at the base and in the middle of the clayey portion from cores 6brip (~118 cm) and 4a (~147 cm), respectively. this deforestation is followed and partly accompanied by the onset of cultivations, which are clearly recorded in the upper part of these two cores, mainly in 6brip (fig. 3). the start of deforestation and of intensive olive cultivation was already pointed out in the salerno gulf and dated to the early middle ages (russo ermolli & di pasquale, 2002). here, the increase of brassicaceae at the core top should represent the cabbage cultivation, which was one of the most common orchard product during the roman age, as testified in the sediments of the ancient roman harbour of naples (1st century bc 5th century ad; allevato et al., 2009; amato et al., 2009). on this basis, despite the lack of definite chronological constraints for these cores, a late holocene time span can be supposed for the analyzed pollen record. it might be tentatively related to about 2000 yr bp in core 6brip (also consistent with the above discussed hypothesis of local sedimentary hiatuses) and possibly to some thousands before in core 4a, where a longer stratigraphic record is included and evidence of deforestation starts only in the mid clayey section. this interpretation is also supported by clear evidence of deforestation and cultivation during about the last 2 ka from another site in calabria, i.e. in the nearby sila massif upland (pelle et al., 2010 and references therein), and a further one in the basilicata region, still in southern italy (allen et al., 2002). in addition to these environmental changes, previous climatic fluctuations could have occurred during the early holocene (and/or the late pleistocene), as revealed by the main features of deeper soils underlying and predating the above archaeological layers (occasional grey glosses and blackish mottles of btg horizons caused by partially impeded drainage and transient reducing conditions, in turn overlying another andic-like a horizon). conclusions the integrated study of seismic profiles, stratigraphic cores and soil profiles located offshore and onshore of the tyrrhenian sea coast of calabria (southern italy) allowed the reconstruction of the main late pleistocene to holocene environmental changes. based on a number of proxies, we identified the major responses of geomorphic processes to changing climatic conditions and human activities. seismostratigraphic interpretation and core stratigraphy, coupled with paleoecological analyses, provided a detailed record of the holocene maximum flooding surface and highstand depositional units of the last marine transgression, which overly the last glacial maximum unconformity. the lateglacial to early holocene climatic amelioration that caused such a sea-level rise, culminated into the mid-holocene (neolithic) climatic optimum, characterized by warm and humid conditions and geomorphic stability, promoting important soil formation under a stable vegetation cover. the variability in depth of andic properties, phyllosilicate formation and illuvial pedofeatures in holocene soils suggests climate changes probably occurred at the transition from the climatic optimum to the cooler but still humid upper holocene, after one or more periods characterized by drought, land degradation, severe soil erosion and human impact during and after the bronze age. this phase was presumably coupled with deforestation and agricultural practices likely more intense during the last 2 ka, clearly highlighted by soil features and pollen analysis in marine cores. references albore livadie c., 1999 archeologia e storia del passato. il bronzo antico. in: fedele f. & petrone p.p. 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(eds.), geoarcheology in italy. méditerranée 112, 137-143. soil survey staff, 2010 keys to soil taxonomy, 11th edit., usda-natural resources conservation service, washington dc, 338 pp. to r t o r i c i g., bi a n c a m., d e gu i d i g., mo n a c o c., tortorici l., 2003 fault activity and marine terracing in the capo vaticano area (southern calabria) during the middle-late quaternary. quaternary international 101-102, 269-278. 270 ms. ricevuto il 23 giugno 2010 testo definitivo ricevuto il 21 novembre 2010 ms. received: june 23, 2010 final text received: november 21, 2010 p.m. bernasconi et al. imp.carveni& il sollevamento della sicilia orientale e alcune implicazioni sismiche e vulcaniche *pietro carveni 1, santo benfatto 2 & maria salleo puntillo 3 1 università di catania, dipartimento di scienze geologiche, sezione di oceanologia e paleoecologia, corso italia 57, 95129 catania, italia, e-mail: carveni@unict.it 2 geologo, libero professionista, via san marco 91, 95047 – paternò (catania) italia, e-mail: benfatto@geologi.it 3 naturalista, via san marco 91, 95047 – paternò (catania) italia, e-mail: maria.salleo@inwind.it riassunto: carveni p., benfatto s. & salleo puntillo m., il sollevamento della sicilia orientale e alcune implicazioni sismiche e vulcaniche. (it issn 0394-3356, 2007). da rilievi effettuati da satelliti, risulta che nell’ambito di un generale sollevamento della sicilia orientale, il settore grossolanamente triangolare dell’edificio vulcanico etneo delimitato a settentrione dal rift di ne e dalla faglia della pernicana, a sw da un sistema di faglie e fratture eruttive con andamento ad arco compreso tra i crateri sommitali e aci castello (sistema montagnola – mascalucia – aci castello), a oriente dalla linea di costa, è caratterizzato da fenomeni di abbassamento. all’interno di questo settore si trovano importanti sistemi di faglie: 1) il sistema giardini – mascali (ne-sw nne-ssw); 2) il sistema ripa della naca piedimonte (ne-sw); 3) il sistema delle timpe (nnw-sse). le informazioni sinora reperite circa l’attività sismica del sistema giardini – mascali si limitano ad una serie di sismi cui è collegata la genesi e l'evoluzione del vulcano di fango salsa di fondachello; solo un sisma di questo sistema, accaduto il 26 marzo 1847, è stato abbastanza intenso da essere registrato a catania; inoltre a tutt’oggi non sono state trovate prove di risalite magmatiche e conseguenti eruzioni collegabili all’attività di questo sistema. al sistema ripa della naca – piedimonte è da attribuire una serie di scosse sismiche avvertite nel paese di piedimonte subito prima e durante l’eruzione etnea del 1928; lungo una delle faglie di questo sistema (ripa di piscio) si aprirono le bocche dalle quali sgorgò la colata lavica che distrusse il paese di mascali. il sistema delle timpe, la cui attività sismica è stata oggetto di numerose osservazioni ad iniziare dal 1805, è responsabile dei più forti terremoti verificatisi sul versante orientale etneo; alcune risalite magmatiche che hanno dato luogo ad eruzioni in tempi storici sono collegate a questo sistema. sulla base di una rilettura critica della letteratura, cui hanno fatto seguito rilievi geologico-geomorfologici di dettaglio, sono state ricostruite le variazioni relative del livello marino in alcuni siti ubicati lungo la costa; i dati evidenziano movimenti differenziali, con innalzamento tra catania e aci castello e abbassamento tra stazzo e torre archirafi. dei fenomeni di abbassamento è responsabile il sistema delle timpe; l’analisi della sismicità di questo sistema per il periodo 1805-1989 ha fornito tassi di abbassamento lungo i piani di faglia compresi tra 2 e 15 mm/anno; questi risultati sono in accordo con i dati di letteratura relativi alla dinamica del versante orientale etneo, il quale risulta soggetto ad un progressivo scivolamento verso ese tramite lo svincolo costituito dalla faglia della pernicana a settentrione e le faglie del sistema montagnola – mascalucia – aci castello a sw. la coincidenza o la vicinanza temporale tra alcune eruzioni verificatesi sul versante orientale dell’edificio vulcanico ed alcuni movimenti sismici avvenuti lungo alcune faglie, che incidono lo stesso versante, fa ipotizzare un collegamento tra i due fenomeni. abstract: carveni p., benfatto s. & salleo puntillo m., eastern sicily uplift and some seismic and volcanic implications. (it issn 0394-3356, 2007). mt. etna is the largest active volcano in europe; it is formed by products of many eruptive centres, which were active in four periods. volcano building is located along the margin of the two main structural domains of eastern sicily: the apennine-maghrebian chain in the north and the hyblaean foreland in the south; the apennine – maghrebian chain consists of several thrust sheets, made up of structural units derived from different palaeogeographical domains; they were overthrusted upon each other during several tectonic phases from eocene to pleistocene. the hyblaean foreland belongs to the northern part of the africa plate; it is formed by a thick triassic to pleistocene carbonate succession, with several intercalations of basic volcanic rocks. while eastern sicily is interested by a general uplift, a sector of the etna volcanic building is characterized by a lowering; this sector is confined by ne rift and pernicana fault in the north, and by montagnola aci castello fault system in the sw; three other fault systems are included in this area; they are: i) giardini – mascali fault system (ne-sw nne-ssw); ii) ripa della naca piedimonte fault system (ne-sw); iii) timpe fault system (nnw-sse). in historical times, the first of these was active only on 26th march 1847; the second system was strongly active during 1928 etna eruption; many earthquakes happened along the timpe fault system from 1805 to present day; they happened sometimes before, during and/or after volcanic eruptions. uplift movements are recorded along the coast between aci castello in the north and catania in the south; some subsidence evidences are visible between torre archirafi in the north and stazzo port in the south; the eastern slope of volcano building is a high seismic hazard zone, with superficial hypocentre earthquakes. parole chiave: sollevamento regionale, sismicità, vulcanismo, geomorfologia. keywords: : regional uplift, seismicity, volcanism, geomorphology. il quaternario italian journal of quaternary sciences 20(1), 2007 57-66 * lavoro presentato al convegno “il sollevamento quaternario nella penisola italiana e nelle aree limitrofe” (roma, 6-8 febbraio 2006) 58 p. carveni, s. benfatto & m. salleo puntillo 1. introduzione alcuni autori, in base a dati provenienti da rilievi in galleria (puglisi, in platania, 1922), studi vulcanologicostrutturali (kieffer, 1983 a; 1983 b; neri et al., 1991; borgia et al., 1992; lo giudice & rasà, 1992; ferrucci et al., 1993; rasà & azzaro, 1995; rasà et al., 1996; bousquet & lanzafame, 2001; obrizzo et al., 2001; tibaldi & groppelli, 2002; neri et al., 2003), macrosismici (azzaro et al., 1989 a; patanè et al., 1994), di sismotettonica (montalto et al., 1996) e geomorfologici (firth et al., 1996), ipotizzano che parte del fianco orientale dell’edificio vulcanico etneo, in contrasto con un generale fenomeno di sollevamento che riguarda tutta la sicilia, trasli verso il mare jonio; la zona, che parte dai crateri sommitali, è delimitata a settentrione dal rift di ne (fig. 1: rne) e dalla faglia della pernicana (fig. 1: fp), faglia diretta con blocco meridionale abbassato e componente laterale sinistra, e a sw dal sistema montagnola – mascalucia – aci castello (fig. 1: smmac), formato da una serie di faglie con componente laterale destra e fratture eruttive disposte ad arco che scendono dai crateri sommitali fino ad aci castello. il primo autore ad individuare il fenomeno è stato puglisi (in platania, 1922); questi aveva riconosciuto una serie di faglie con direzione generale n-s (sistema di aci sant’antonio, sas in fig. 1), le quali interessano il versante compreso tra aci bonaccorsi (fig. 1: ab) e la falesia di acireale (fig. 1: a); in particolare aveva rilevato, lungo alcune gallerie drenanti, sia il rigetto verticale, sia lo spostamento orizzontale verso oriente; questo fenomeno era stato ipotizzato come reazione di una parte dell’edificio etneo al graduale sollevamento della zona (platania, 1922). kieffer (1983 a; 1983 b) ipotizza scivolamenti gravitativi di parte del versante orientale dell'edificio vulcanico etneo, attribuendone la genesi alla ripetuta intrusione di magma attraverso il rift di ne e un rift meridionale. azzaro et al. (1989 a), analizzando i dati ricavati dallo studio del terremoto di codavolpe (catania) del 29 gennaio 1989, ritengono che l'evento sia stato di natura essenzialmente gravitativa e geneticamente collegato all'instabilità del versante orientale etneo. neri et al. (1991) descrivono una serie di deformazioni osservate sul versante orientale etneo, compatibili con un movimento del versante verso oriente. borgia et al. (1992), in base ai risultati ottenuti da ferrari et al. (1991) dallo studio dei dicchi affioranti nella valle del bove, ipotizzano uno spreading radiale del substrato dell'etna verso se. lo giudice & rasà (1992) ritengono invece che si tratti di movimenti puramente gravitativi, che provocano lo scivolamento verso sse della porzione dell'edificio etneo delimitata a settentrione dalla faglia della pernicana e dal rift di ne, e a se dalle faglie di mascalucia e trecastagni. ferrucci et al. (1993), rasà & azzaro (1995) e rasà et al. (1996), in contrasto con borgia et al. (1992) ritengono che solo la porzione del versante orientale etneo, delimitata a settentrione dal rift di ne e dalla faglia della pernicana, e a se dalle faglie di mascalucia e trecastagni, subisca un movimento verso oriente; la causa sarebbe da attribuire a movimenti gravitativi, condizionati da una vasta e profonda superficie di distacco. patanè et al. (1994) ipotizzano che lo spreading gravitazionale verso oriente del settore orientale dell'edificio etneo abbia influenza sul fagliamento superficiale. firth et al. (1996) attribuiscono l'instabilità del versante orientale etneo ad un sollevamento in blocco di tutta la parte nord-orientale della sicilia, cui hanno fatto seguito movimenti superficiali del versante, su un basamento sub-vulcanico che ha subito un sollevamento regionale. montalto et al. (1996), esaminando la sismicità recente dell'etna (dall'aprile 1989 al dicembre 1991), ipotizzano che lo scivolamento del versante orientale etneo riguardi una serie di blocchi che si muovono singolarmente. secondo bousquet & lanzafame (2001) le intrusioni magmatiche che danno luogo alle eruzioni sommitali causano uno spostamento verso oriente solo della parte sommitale del vulcano. obrizzo et al. (2001), esaminando gli effetti cosismici registrati lungo la faglia della pernicana nell'arco di 17 anni, giungono alla conclusione che il versante orientale etneo scivola verso il mare, a causa dell'azione combinata dell'accelerazione di gravità e delle intrusioni magmatiche; la faglia della pernicana rappresenterebbe il limite settentrionale della zona in movimento. secondo tibaldi & groppelli (2002) il movimento traslativo del versante orientale dell'etna verso il bacino ionico sarebbe dovuto a due distinte cause: in profondità le intrusioni magmatiche provocherebbero lo slittamento dei terreni appartenenti all'orogene appenninico – maghrebide sul sottostante plateau ibleo, mentre in superficie il movimento sarebbe di origine prevalentemente gravitativo e localizzato lungo il contatto tra le argille pleistoceniche del basamento etneo e i terreni sottostanti. neri et al. (2003), monitorando i movimenti avvenuti durante l'eruzione etnea 2002 – 2003 lungo la faglia della pernicana, il sistema di faglie delle timpe e la faglia di trecastagni, ipotizzano che il versante orientale etneo sia stato interessato dal movimento verso lo jonio di una massa con volume superiore a 1.100 chilometri cubi; il movimento non sarebbe avvenuto interessando un unico blocco, ma due distinte zone del fianco orientale etneo. 2. inquadramento geologico-strutturale i domini strutturali del bacino del mediterraneo centrale, nel quale si inserisce la sicilia, sono geneticamente collegati alla collisione tra la placca africana e la placca europea; le due masse continentali si scontrano e si saldano tra loro, originando l’orogene appenninico – maghrebide, una catena corrugata che forma la dorsale appenninica e, attraversando l’arco calabro, la sicilia e lo stretto di sicilia, prosegue lungo le coste nord-africane del maghreb. nella zona orientale della sicilia la crosta oceanica ionica e la crosta continentale dell’avampaese ibleo si immergono sotto il fronte dell’orogene appenninicomaghrebide (finetti et al, 1996) (fig. 2). le falde neogeniche dell’orogene appenninico maghrebide sovrascorrono sull’avampaese ibleo, zona fig. 1 schema tettonico del versante orientale etneo (da carveni et al., 2005 a). a) principali sistemi di faglie: sgm) sistema giardini – mascali: fcm) faglia capo schisò – foce del torrente macchia; ff) faglia di fondachello; fg) faglia di giardini; fn) faglia di naxos. smmac) sistema montagnola – mascalucia – aci castello: fma) faglia di mascalucia; ft) faglia di trecastagni; srmp) sistema ripa della naca – piedimonte: frn) faglia della ripa della naca; frp) faglia della ripa di piscio; sas) sistema di sant'antonio; st) sistema delle timpe: fm) faglia di moscarello; fms) faglia macchia – stazzo; fsl) faglia di san leonardello; b) centri abitati: a) acireale; ab) aci bonaccorsi; ac) aci catena; as) aci sant'antonio; fi) fiumefreddo; fm) fondo macchia; fo) fondachello; g) giardini; gi) giarre; m) mascalucia; ma) mascali; s) stazzo; sa) sant'alfio; sg) san giovanni montebello; cma) contrada monti arsi; t) trecastagni; ta) torre archirafi; c) centri eruttivi: cc) cratere centrale; cu) cono di cenere di contrada cutula. i triangoli indicano zone in cui sono stati misurati sollevamenti e abbassamenti fino a 15 mm/anno (gironi et al., 2003). tectonic scheme of mount etna volcano eastern slope (after carveni et al., 2005 a); a) main fault systems: sgm) giardini – mascali fault system: fcm) cape schisò – macchia stream mouth fault; ff) fondachello fault; fg) giardini fault; fn) naxos fault; smmac) montagnola – mascalucia – aci castello fault system: fma) mascalucia fault; ft) trecastagni fault; srmp) ripa della naca – piedimonte fault system: frn) ripa della naca fault; frp) ripa di piscio fault; sas) sant'antonio fault system; st) timpe fault system: fm) moscarello fault; fms) macchia – stazzo fault; fsl) san leonardello fault; b) towns: a) acireale; ab) aci bonaccorsi; ac) aci catena; as) aci sant'antonio; fi) fiumefreddo; fm) fondo macchia; fo) fondachello; g) giardini; gi) giarre; m) mascalucia; ma) mascali; s) stazzo; sa) sant'alfio; sg) san giovanni montebello; cma) contrada monti arsi; t) trecastagni; ta) torre archirafi; c) eruptive centres: cc) central crater; cu) contrada cutula cinder cone. triangles indicate uplift or lowering zones up to 15 mm/y (after gironi et al., 2003). 60 stabile facente parte del margine della placca africana (burollet et al., 1978); esso è costituito da una potente successione prevalentemente carbonatica compresa, con lacune stratigrafiche, tra il trias e il pleistocene medio; vi si intercalano prodotti effusivi basici cretacei, miocenici e plio-pleistocenici, la cui risalita è stata favorita da intense fasi tettoniche distensive (cristofolini, 1966; di grande, 1967; 1969; 1972; carbone et al., 1987; amore et al., 1988; carveni et al., 1991 a; 1991 b; 1993; carveni & sturiale, 1999). l’avampaese ibleo confina ad oriente con la crosta oceanica del bacino ionico (f inetti, 1982) tramite la scarpata ibleo maltese, la quale è l’espressione morfologica di un sistema di faglie normali a gradinata, il cui prolungamento verso settentrione interseca il fianco orientale dell’edificio vulcanico etneo (cristofolini et al., 1979). la scarpata si è formata in un’unica grande fase tortoniana, con minori riattivazioni posteriormente al deposito dei trubi (pliocene inferiore), e a luoghi le sono connesse importanti attività vulcaniche (casero et al., 1984). lanzafame & bousquet (1997) ritengono che la scarpata ibleo maltese sia un segmento di un importante sistema di faglie con direzione compresa tra nnw-sse e nw-se, che, attraversando la sicilia nordorientale e il mar tirreno meridionale, raggiunge le isole vulcano, lipari e salina. le unità della catena kabilo – calabride (fig. 2: ckc), costituite da falde di basamento cristallino interessate da metamorfismo ercinico con resti dell’originaria copertura sedimentaria meso-cenozoica, sono sovrascorse sulle unità della catena appenninico maghrebide, in concomitanza dell’apertura del bacino balearico – provenzale e la rotazione del blocco sardo – corso (de jong et al., 1973). la catena appenninico – maghrebide (cam in fig. 2) è costituita da falde sud-vergenti, il cui corrugamento ha interessato, deformandole, le coperture sedimentarie della tetide e dei paleodomini minori ad essa associati, originariamente posti tra il margine della placca europea e il margine della placca africana (finetti et al., 1996). in questo quadro geodinamico compressivo, nel pleistocene inferiore sono iniziate intense fasi tettoniche che hanno causato un’elevata distorsione lungo il margine settentrionale della placca africana, a causa della differente velocità con cui avviene la subduzione al di sotto della catena appenninico maghrebide (morelli, 1970), e ciò ha determinato uno stiramento crostale che ha dato luogo a fratture con direzione nwse, ne-sw ed e-w (ghisetti & vezzani, 1982); all’intersezione di tali strutture si è formata una zona di debolezza attraverso la quale avviene la risalita di magmi sub-crustali (frazzetta & villari, 1981) che hanno dato luogo al complesso edificio vulcanico etneo. il monte etna, con la sua altitudine di poco superiore ai 3.300 metri e col diametro massimo di 44 chilometri, è il maggiore vulcano attivo del continente europeo; esso è uno strato-vulcano complesso, risultante dalla sovrapposizione di prodotti emessi da diversi edifici (gemmellaro, 1858) poggianti su un basamento in parte alloctono, formato da rocce di età compresa tra il cretaceo ed il pleistocene (romano et al., 1979; lentini, 1982). sulla genesi del vulcano e sul quadro strutturale sono stati proposti numerosi modelli, tra i quali: 1) intersezione di importanti lineamenti strutturali, come la scarpata ibleo-maltese e l’allineamento messina-giardini (ogniben et al., 1975; mcguire et al., 1997); 2) formazione di un graben nell’area dell’attuale piana di catania a causa di tettonica estensionale (di geronimo et al., 1978); 3) processi di rifting tra il blocco maltese-siciliano e il bacino ionico (gillot et al., 1994, continisio et al., 1997); 4) deformazione al footwall di una faglia normale appartenente al sistema distensivo siculo-calabro ad andamento wnw-ese (monaco et al., 1997); 5) risalita magmatica mantellica causata dalla presenza di un hot spot (tanguy et al, 1997); 6) roll-back di una porzione di litosfera subdotta al di sotto del mar tirreno (gvirtzman & nur, 1999). fig.2 schema strutturale della sicilia (da finetti et al., 1996). ai) avampaese ibleo; cam catena appenninico – maghrebide; ckc) catena kabilo – calabride; cs) catena sicana; e) edificio vulcanico etneo; agc) avanfossa gela – catania; sim) scarpata ibleo – maltese; smf) sistema di faglie messina – fiumefreddo; il rettangolo indicato dalla freccia corrisponde alla zona in studio. structural scheme of sicily (after finetti et al., 1996). ai) hyblaean foreland; cam) apennine – maghrebian chain; ckc) kabilo – calabrian chain; cs) sicania chain; e) mount etna volcano; agc) gela catania foredeep; sim) hyblaean – malta escarpment; narrow indicates position of studied area. p. carveni, s. benfatto & m. salleo puntillo 61 l’attività eruttiva dell’etna, inizialmente sottomarina e fissurale, è diventata in seguito subaerea ed a carattere centrale, con emissioni da numerosi apparati eruttivi (romano, 1982). gillot et al. (1994), sulla base del rapporto k/ar, hanno distinto quattro periodi di attività dell’etna, alternati a lunghi periodi di quiescenza: il primo periodo (da 520.000 ± 40.000 a 270.000 anni fa) fu caratterizzato da emissioni di lave a composizione tholeiitica attraverso apparati fissurali; il secondo periodo (da 168.000 ± 8.000 a 100.000 anni fa) vide un radicale cambiamento del chimismo del magma, da sub-alcalino ad alcalino, e del tipo di attività, da eruzioni fissurali a eruzioni da condotti centrali, con la conseguente formazione di strato-vulcani; durante il terzo periodo (tra 80.000 e 60.000 anni fa) si formò un grande complesso vulcanico poligenico, denominato trifoglietto; nel quarto periodo (da 35.000 anni fa ad oggi) si è sviluppato il mongibello, un grande strato-vulcano; un’importante fase, caratterizzata da intense eruzioni pliniane e idromagmatiche, permette di suddividere questo periodo in due parti: mongibello antico e mongibello recente. 3. sismicità delversante orientale etneo in precedenti articoli è stata esaminata la sismicità del versante orientale etneo, geneticamente collegata al sistema di faglie delle timpe, e caratterizzata da terremoti con ipocentri superficiali, con profondità compresa tra 0,5 e 2 chilometri (patanè, 1975; benina et al., 1984; lo giudice, 1985; bottari et al., 1989; azzaro et al., 1989 a; 1989 b; lo giudice & rasà, 1992; adorni & carveni, 1993 a; 1993 b; carveni & bella, 1994; bella et al., 1996; carveni et al., 1996; gresta et al., 1997; carveni et al., 1997; ferreli et al., 2000), modesto raggio di avvertibilità e campo macrosismico di pochi chilometri quadrati; come effetto cosismico è stata spesso segnalata l’apertura di fessure nel terreno (grassi, 1865; silvestri, 1865; 1866; 1867; 1883; platania & platania, 1894; platania, 1908; 1920; riccò, 1911; 1912; sabatini, 1914; castorina, 1920; cumin, 1954; riuscetti & distefano, 1971; azzaro et al., 1989 a) e l’innesco di frane lungo pendii instabili (grassi, 1865); la zona è inoltre interessata da fenomeni di creep asismico (lo giudice, 1985). come è stato già accennato, il settore delimitato a settentrione dal rift di ne e dalla faglia della pernicana e a meridione dal sistema montagnola – mascalucia – aci castello, secondo le ipotesi di numerosi autori già citati nell'introduzione, sarebbe interessato da fenomeni di scivolamento verso se; all'interno di questo settore si trovano altri sistemi di faglie, i più importanti dei quali sono: 1) la parte meridionale del sistema giardini – mascali (sgm in fig. 1), con direzione nne-ssw; 2) il sistema ripa della naca – piedimonte (srnp in fig. 1), con direzione ne-sw; 3) il sistema delle timpe (st in fig. 1). le faglie del sistema giardini – mascali costituiscono il prolungamento dell’allineamento messinagiardini di ogniben et al. (1975), che viene intersecato dalla faglia della pernicana a meridione di fiumefreddo; l’attività sismica in tempi storici di questo sistema, sulla base delle informazioni sinora raccolte, è limitata ad una serie di terremoti avvertiti solo in ambito locale nei dintorni di mascali e fondachello; a questa sismicità è stata collegata l’evoluzione di un vulcano di fango conosciuto come salsa di fondachello (mercurio, 1847). l'unico sisma di un certo rilievo è avvenuto il 27 marzo 1847, e fu avvertito lungo la fascia ionica fino a catania; la profondità ipocentrale di questo sisma, anche se non è mai stata calcolata, deve essere maggiore a quelle dei sismi relativi al sistema delle timpe. il secondo sistema è stato attivo in occasione dell'eruzione etnea del 1928: una serie di 13 sismi fu avvertita a piedimonte etneo (pe in fig. 1) tra il 2 e il 9 novembre (azzaro et al., 2000); si trattò chiaramente di movimenti lungo una o entrambe le faglie del sistema, attivatesi in concomitanza della fuoriuscita della colata dalla frattura estensionale apertasi alla base del piano della faglia della ripa di piscio; gli epicentri macrosismici sono stati localizzati a piedimonte etneo in quanto questo centro abitato è ubicato lungo il prolungamento dei piani di faglia, e corrisponde alla zona abitata maggiormente investita dalle onde sismiche. il sistema delle timpe è il più attivo dei tre; ad esso sono legati i più forti terremoti avvenuti nella zona etnea (carveni & bella, 1994); è ipotizzabile che questo sistema di faglie, rispetto a come è stato cartografato sulla carta geologica del monte etna (romano et al., 1979), si inoltri per diversi chilometri verso nnw, ma non se ne hanno evidenze morfologiche a causa della copertura da parte di colate laviche. all'attività di questo ultimo sistema di faglie, oltre che una discreta serie di terremoti registrati ad iniziare dal 1805 (malgrado la zona sia stata intensamente abitata dall'epoca classica non si è riusciti a trovare testimonianze di terremoti anteriori a questo anno), sono attribuiti i fenomeni di abbassamento registrati lungo la linea di costa (carveni et al., 2005 b). 4. testimonianze di instabilità del versante orientale dell'etna che nella sicilia orientale sono presenti numerosi indizi sia geologici sia geomorfologici di variazioni del livello del mare verificatisi nel corso del quaternario è noto: già a partire dal xix secolo sono reperibili in letteratura dati relativi a testimonianze geologico-geomorfologiche di antichi livelli del mare; secondo le nostre ricerche bibliografiche il primo a riconoscere queste testimonianze lungo la costa ionica è stato gemmellaro (1837), il quale ha descritto il solco di battente esistente attorno ai promontori di capo sant’alessio e capo sant’andrea, nei pressi di taormina. recentemente (carveni et al., 2005 b) è stata effettuata una rilettura critica degli articoli in cui si descrivono le tracce geologico-geomorfologiche del graduale sollevamento della zona costiera compresa tra ògnina a meridione (sollevamento di circa 1 metro) e aci castello a settentrione (13 metri); in quest’ultima località ad un progressivo innalzamento a scatti è intercalato un fenomeno di abbassamento, avvenuto posteil sollevamento della sicilia ... 62 riormente all’arrivo di una colata lavica, datata al periodo compreso tra il 122 a.c. e il 252-253 d.c. (romano & sturiale, 1981); più a settentrione, nel porto peschereccio di stazzo (fig. 2: s) e a torre archirafi (fig. 2: ta) vi sono evidenze di un progressivo abbassamento della zona costiera, collegato all’attività delle faglie del sistema delle timpe (carveni et al., 2005 a; 2005 b). l’attività delle faglie del sistema delle timpe è documentata ad iniziare dal 1805 (anno del più antico terremoto di cui si sia conservata la memoria) con sempre maggiore attenzione. è stato evidenziato che gli epicentri dei sismi sono localizzati prevalentemente lungo i segmenti settentrionali delle relative faglie, mentre lungo i tratti meridionali delle stesse si registrano solo fenomeni di creep asismico (carveni & bella, 1994). l’integrazione tra dati provenienti da indagini geoelettriche (cassinis et al., 1970) e dati relativi alle profondità ipocentrali di alcuni sismi (patanè, 1975; postpischl, 1985; azzaro et al., 1989 a; 1989 b; bottari et al., 1989) evidenziando che gli ipocentri di alcuni terremoti sono ubicati al contatto tra le vulcaniti, a comportamento geomeccanico fragile, e le sottostanti argille infra-pleistoceniche, ha fatto ipotizzare una genesi di tipo gravitativo profondo per i movimenti sismici in oggetto (carveni & bella, 1994). 5. fenomeni vulcanici conseguenti all’instabilita’ del versante orientale etneo carapezza (1962) per primo ha tentato di determinare una relazione tra la tettonica regionale e le zone di minore resistenza dell'edificio vulcanico; egli ha riconosciuto una zona di rift che attraversa il fianco orientale del vulcano, corrispondente a quello che verrà in seguito chiamato sistema delle timpe. in verità, fatta eccezione per un minuscolo edificio ubicato in località cutula (fig. 2: cu), attribuito all'attività dei centri eruttivi alcalini antichi (romano et al., 1979), e la cui genesi può essere attribuita ipoteticamente al punto di incontro tra il sistema giardini – mascali e il sistema delle timpe, allo stato attuale delle ricerche non vi sono ulteriori testimonianze di attività vulcanica collegabile a questi due sistemi di faglie per la zona del basso versante orientale etneo, studiato da carapezza (1962). altri autori che più recentemente si sono interessati di questi sistemi di faglie sono adorni & carveni (1993 a; 1993 b); carveni & bella (1994); bella et al. (1996); carveni et al. (1996; 1997); gresta et al. (1997); monaco et al. (1997); monaco & tortorici (2000); ferreli et al. (2000). un'eruzione che invece risulta chiaramente essere fig. 3 schema morfo-tettonico della zona dei monti sartorius (da carveni & benfatto, 2004). a) faglie; b) fratture eruttive; c) coni piroclastici: 1) monte corvo; 2) monte baracca; 3 e 4) i due monti; 5) monte zappinazzo e monti conconi; 6) monte frumento delle concazze; 7) edificio anonimo a sud-ovest di monte frumento delle concazze; 8) monti sartorius; 9) bocche del 1928; d) orlo della valle del bove; e) alti morfologici: 10) monte crìsimo; 11) monte ragamo; 12) monte chiovazzi. morpho-tectonic scheme of the monti sartorius zone (after carveni & benfatto, 2004). a) faults; b) eruptive fractures; c) cinder cones: 1) monte corvo; 2) monte baracca; 3 and 4) i due monti; 5) monte zappinazzo and monti conconi; 6) monte frumento delle concazze; 7) no name cinder cone sw from monte frumento delle concazze; 8) monti sartorius; 9) 1928 eruption’s vents; d) valle del bove rim; e) peaks: 10) monte crìsimo; 11) monte ragamo; 12) monte chiovazzi. p. carveni, s. benfatto & m. salleo puntillo stata alimentata da due sistemi di faglie, rispettivamente con direzione ene-wsw e nnw-sse è quella avvenuta nel 1865, e che ha dato origine agli edifici denominati monti sartorius (fig. 3). come è stato evidenziato (carveni et al., 1998; 2000; carveni & benfatto, 2004) la disposizione delle bocche eruttive dimostra chiaramente la presenza di due distinti sistemi di fratture eruttive: un sistema principale ene-wsw, parallelo al sistema ripa della naca – piedimonte, e un sistema nnw-sse, attribuibile ad un ipotetico prolungamento verso nnw del sistema delle timpe. l'ipotesi è suffragata da una serie di scosse premonitrici che avevano allarmato gli abitanti di san giovanni (fig. 2: sg), di sant'alfio (fig. 2: sa) e della contrada monti arsi (fig. 2: cma), località ubicate lungo l'ipotizzato prolungamento verso nnw del sistema delle timpe; nel momento in cui iniziava l'eruzione lungo la frattura principale (ene-wsw), un sisma del 5° o 6° della scala mercalli, fece uscire dalle case gli abitanti delle suddette zone in preda al panico; lo stesso sisma fu avvertito ad acireale (fig. 2: a), ma non a giarre (fig. 2: gi); ciò confermerebbe l'ipotesi che si sia trattato di un movimento lungo una delle faglie del sistema delle timpe (carveni & benfatto, 2004). 6. conclusioni l’analisi della sismicità e di parte dell’attività vulcanica verificatesi nell’area oggetto di studio suggerisce che i due principali sistemi di faglie attive della zona sono collegabili geneticamente a fenomeni gravitativi profondi, e ciò in accordo con le ipotesi di rasà et al. (1996) e neri et al. (2003). il sistema ripa della naca – piedimonte, oltre a dare luogo a faglie sismicamente attive, è stato interessato in tempi storici da almeno tre eruzioni: 1865, 1928 e 1971 (fig. 3). si ipotizza, per l’eruzione del 1865, che la risalita magmatica sia iniziata attraverso il condotto centrale e da qui si sarebbe spostata verso il fianco orientale attraverso una serie di fratture radiali, le quali, nella parte periferica, hanno una loro prosecuzione nel sistema timpa della naca – piedimonte; l’intrusione magmatica ha trovato delle vie di risalita preferenziali nell’intersezione con il sistema di faglie delle timpe (carveni & benfatto, 2004); i sismi antecedenti e concomitanti con l’eruzione, chiaramente collegati all’attività di questo ultimo sistema, rafforzano l’ipotesi. fenomeni analoghi sono stati registrati nel corso delle eruzioni del 1928 e del 1971; nel primo episodio l’eruzione iniziò dalla zona sommitale, per spostarsi in seguito sul versante nord-orientale; nella fase finale avvenne l’apertura di bocche eruttive in corrispondenza della faglia della ripa di piscio. uno sciame sismico fu avvertito subito prima e in concomitanza dell’apertura di queste ultime bocche dagli abitanti di piedimonte, centro abitato ubicato esattamente lungo la prosecuzione del sistema di faglie. nel 1971 la prima fase dell’eruzione avvenne nella zona sommitale; quindi si aprì una frattura eruttiva sul versante nord-orientale, parallelamente a quella del 1928; nel corso dell’eruzione un sisma di intensità pari al viii ix grado mcs danneggiò gravemente sciara, frazione di s. giovanni (sg, in fig. 1), ubicata lungo la prosecuzione del sistema delle timpe. la concomitanza, tra un terremoto causato dalla faglia di moscarello (sistema delle timpe) durante un'eruzione lungo una frattura del sistema timpa della naca piedimonte, sosterrebbe l'ipotesi di un collegamento tra i due sistemi. nel 2002, ad uno scivolamento per blocchi del settore est dell’edificio etneo (neri et al., 2003) seguì dapprima un sisma dell’viii grado mcs (azzaro et al., 2006) e successivamente una eruzione che iniziò dal rift di ne e proseguì sul versante meridionale (ingv, 2003), interessando così la parte più elevata della “zona di distacco” del versante orientale. tutto ciò sarebbe da mettere in relazione con i fenomeni di instabilità che interessano il settore orientale etneo, il quale tende a scivolare verso il mare jonio, come è già stato ampiamente ipotizzato da diversi autori ad iniziare dal secolo scorso, e ci porta ad aderire ai modelli interpretativi presentati da rasà et al. 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(1982) succession of the volcanic activity in the etnean region. mem. soc. geol. it., 23, 2748. romano r., lentini f., sturiale c., amore c., atzori p., carter s.r., cristofolini r., di geronimo i., di grande a., duncan a.m., ferrara v., ghisetti f., guest j.e., hamill h., patanè g., pezzino a., puglisi d., schilirò f., torre g. & vezzani l. (1979) carta geologica del monte etna, scala 1:50.000, litogr. art. cartogr., firenze. romano r. & sturiale c. (1981) geologia del versante sud-orientale etneo, f°. 270 iv (no, ne, so, se). boll. soc. geol. it., 100 (1), 11-40. sabatini v. (1914) note sul terremoto di linera dell'8 maggio 1914. boll. r. comit. geol. it., 44, 245293. s ilvestri o. (1865) relazione sopra i terremoti dell’etna. stabilimento tipografico “la fenice”, catania, 12 pp. silvestri o. (1866) sull'eruzione dell'etna del 1865. studi geologici e chimici. "nuovo cimento", 2122, 20 pp. silvestri o. (1867) i fenomeni vulcanici presentati dall’etna nel 1863-64-65-66 considerati in rapporto alla grande eruzione del 1865. mem. acc. gioenia sc. nat., 3 (1), 53-319. silvestri o. (1883) sulla esplosione etnea del 22 marzo 1883 in relazione ai fenomeni vulcanici (geodinamici ed eruttivi) presentati dall'etna durante il quadriennio compreso dal gennaio 1880 al dicembre 1883. osservazioni e studi. att. acc. gioenia sc. nat., 3 (18), 237-421. tanguy j.c., condomines m. & kieffer g. (1997) evolution of the mount etna magma: constraints on present feeding system and eruptive mechanism. jour. volc. geot. res., 75, 221-250. tibaldi a. & groppelli g. (2002) volcano-tectonic activity along structures of the unstable ne flank of mt. etna (italy) and their possible origin. jour. volc. geoth. res., 115, 277-302. 66 ms. ricevuto il 16 maggio 2006 testo definitivo ricevuto il 4 gennaio 2007 ms. received: may 16, 2006 final text received: january 4, 2007 p. carveni, s. benfatto & m. salleo puntillo imp.antonioli& lo studio della sezione “il fronte” per la definizione del piano tarentiano (puglia, italy) fabrizio antonioli1, alan deino2, luigi ferranti3, joerg keller4 , stefano marabini5, giuseppe mastronuzzi6, alessandra negri7, andrea piva8, gian battista vai5 & luigi vigliotti8 1enea, cre casaccia, roma italy 2berkeley geochronology center, usa 3dipartimento di scienze della terra, universita' federico ii, napoli, italy 4mineralogisch-geochemisches institut albert-ludwigs-universität, germany 5dipartimento di scienze della terra e geologico-ambientali, universita` di bologna, italy 6dipartimento di geologia e geofisica università degli studi di bari, italy 7dipartimento di scienze del mare universita' politecnica delle marche, italy 8ismar cnr bologna abstract: f. antonioli, a. deino, l. ferranti, j. keller, s. marabini, g. mastronuzzi, a. negri, a. piva, g.b.vai & l. vigliotti , the study of “il fronte” section to define the tarentian stage (puglia, italy). the italian commission on stratigraphy of the sgi is seeking for a marine section suitable for defining the upper pleistocene gssp. this series has been usually identified with the tyrrhenian stage which in the wake of formalization received different meaning from stratigraphers and geomorphologits. hence, the proposal of a new upper pleistocene stage name and type area, the tarentian, created in 1994. criteria for defining the tarentian stage and selecting its gssp can be the beginning of mis 5 (~ 134 ka) and the beginning of mis 1 (~ 10 ka) taken for the base of the holocene. the tarentian stage also contains mis 5.5 highstand with its peak at ~ 125 ka. upper pleistocene marine deposits of thickness exceeding 1 to 2 m are rarely exposed on land except for some mediterranean countries. italian coastal areas keep some hundreds of marine upper pleistocene sites. they are some characterized by the strombus bubonius senegalese tropical fauna. they are found at different elevations from -130 to +170 m depending on the strong differential crustal mobility of the area. the best up to some 10 m thick upper pleistocene marine sections are exposed at the coast of the gulf of taranto facing the ionian sea. here the regional uplift is less intense than at the apulian apennine front where it postdates mis 15. thus, there is a greater chance of finding part of the tarentian stage deposited in marine conditions. first results from the "il fronte" section in a km-long coastal cliff show from the base made by the plio-pleistocene blue clay fm.: (1) ~ 4 m thick massive to silty grey marine clay rich in planktic forams suggesting temperature fluctuations in a slope environment. the interval has normal magnetic polarity and the nanno plankton suggests a middle pleistocene age possibly in the range of 0,577 ma (lo g. omega) to 0,430 ma (lo p. lacunosa). (2) the top of this clay is marked by a two cm-thick white glass-rich high-potassic distal tephra horizon followed by a well laminated 20 cm-thick sapropel. shortly before the tephra, the forams indicate decreasing bottom oxygenation. (3) ~ 1.5 m of greygreen normal marine outer shelf mudstone passing upward to inner mudstone shelf. it is gradually succeeded by the over two m-thick subtidal strombus calcarenite yielding a 126 ka tims date. the rapid shallowing between (2) and (3) may suggest an omission gap. however, normal marine mudstone at least 1.5 m-thick underlies the shallow-water calcarenite which represents mis 5.5. within this continuous mudstone interval beneath the calcarenite the upper pleistocene gssp can be properly placed, and easily correlated with the continuous deep cores of the ionian sea and the oceans. parole chiave: mis 5.5, tarentiano. keywords: mis 5.5, tarentian. il quaternario italian journal of quaternary sciences 21(1a), 2008 35-38 l'international union of geological sciences (iugs) ha spronato l'international commission on stratigraphy (ics) a completare la definizione formale degli stratotipi del limite (gssp) dei piani della scala cronostratigrafica standard ancora non formalizzati entro tempi ragionevoli. ciò è avvenuto anche sotto lo stimolo della segreteria generale dell'iugs tenuta dall'italia in vista del 32° international geological congress (igc) di firenze 2004 organizzato dall'italia. l'obiettivo era di compiere l'opera entro l'igc di brisbane 2012. lo scopo era di avere un quadro certo di riferimento e stabile nel significato dei nomi cronostratigrafici, tale da garantire un linguaggio comune globale (italian commission on stratigraphy 2002; vai 2001, 2007). l'italia ha attivamente contribuito a quest'opera ottenendo l'approvazione di alcuni gssp sul territorio nazionale per piani del trias, del paleogene, del neogene (in particolare zancleano, piacenziano, gelasiano) e per il quaternario (pleistocene inferiore) (fig.1). il limite inferiore del pleistocene superiore è altrettanto, se non più importante perché rappresenta l'inizio dell'ultimo e massimo intervallo di riscaldamento naturale della storia recente della terra prima del riscaldamento in corso in presenza di marcata attività antropica. dopo il 32° igc firenze 2004, il nuovo presidente della subcommission of quaternary stratigraphy (sqs) dell'ics, prof. philip gibbard, ha comunicato che in mancanza di altre proposte migliori, si sarebbe a malincuore risolto a proporre il gssp del pleistocene superiore alla base del piano storico eemiano di ambiente continentale che, per essere mal esposto, 36 f. antonioli et al. (hearty e dai prà 1989, belluomini et al., 2002) sito in puglia presso taranto (mar piccolo), prescelto in base alle caratteristiche geomorfologiche e stratigrafiche (antonioli et al., 2007) quale sito potenziale del gssp. da un punto di vista geologico, il piano tirreniano scoperto e definito per la prima volta da issel (1914) a cala mosca in sardegna, è caratterizzato da depositi bioclastici di mare basso dello spessore da pochi decimetri al metro, con faune marine tropicali contenenti ospiti caldi tra i quali strombus bubonius sempre in discontinuità più o meno marcata sul substrato. questi depositi appaiono come il prodotto di una trasgressione talora erosiva su altri depositi marini, oppure più graduale su un substrato pedogenizzato o formato da depositi continentali. in ferranti et al., 2006, sono riassunte le descrizioni di 234 sezioni pubblicate in tutta italia, e l'interpretazione sismotettonica delle notevoli variazioni altimetriche riscontrate sulle coste italiane (da -130 a +170 m). l'unica area in cui, sotto tali depositi compaiono argille marine in apparente continuità e conformità è il bordo del golfo di taranto dove anche gli spessori della panchina fossilifera raggiungono i massimi di 5-6 m. nella penisola salentina, invece, la successione è meno spessa e poggia sempre sopra peliti continentali. quanto sottolineato sopra non deve sorprendere perché il golfo di taranto, e il mar piccolo in particolare, occupano una posizione geotettonica speciale. si trova infatti a cavallo di una zona di trascorrenza estovest di attivazione assai recente, che è sovrimposta a una ubicazione geodinamica speciale: vicina al fronte della catena appenninica e, più precisamente, al margine esterno della avanfossa bradanica e del suo cercine periferico (peripheral bulge) costituito dalla penisola salentina (bigi et al. 1992, vai and martini 2001). il sollevamento del fronte della catena a montalbano ionico è posteriore almeno al mis 15 (cfr. ciaranfi et al. 2007), verrebbe ubicato in una carota perforata a amsterdam. il presidente era conscio che una tale procedura sarebbe stata scorretta per essere in disaccordo con i principi e la pratica consuetudinaria stratigrafica. perciò si augurava che l'italia o altri paesi mediterranei preparassero proposte alternative. perciò, la commissione italiana di stratigrafia ha nuovamente chiesto a un gruppo di specialisti italiani di verificare la fattibilità di proposte alternative per la scelta del gssp di questo limite. i primi risultati di questo tentativo sono stati incoraggianti. esposti all'ultimo congresso mondiale dell'inqua a cairns nel luglio 2007, hanno riscosso l'interesse del prof. gibbard che ha richiesto una ricerca completa e approfondita che consentisse di presentare all'igc oslo 2008 una prima proposta sulle potenzialità di sezioni marine del nuovo piano tarentiano, e poi entro un altro anno al massimo una proposta formale completa da mettere al ballottaggio con la proposta olandese. il nuovo piano inizia tra la fine del mis (marine isotope stage) 6 e l'inizio del mis 5, (circa 134 ka), e termina con l'inizio del mis 1(10 ka). questo piano contiene anche il mis 5.5 il cui acme viene fatto risalire a 125 ka noto nel mediterraneo con il termine tirreniano dall'omonimo piano definito a suo tempo da issel nel 1914 (vai, 1996; cita et al., 2006) e mai formalizzato, come tanti altri piani. ne è derivato un uso difforme fra stratigrafi e geomorfologi. paradossalmente, questo limite non è stato studiato, nonostante l'esplicito invito della commissione italiana di stratigrafia che nel 1994 aveva sollecitato la comunità italiana a farlo e aveva proposto di sostituire il nome tirreniano con tarentiano indicando con ciò l'area di studio più promettente (cita e castradori, 1994). scopo della nostra ricerca e' dunque la formulazione di una proposta per il gssp del tarentiano presso la località “il fronte” a taranto. i principi e la pratica stratigrafica prevedono che lo stratotipo del limite di una unità cronostratigrafica standard (cioè a validità globale) sia posto in una successione marina, continua per almeno un certo tratto in cui si trova il limite, di ambiente pelagico non torbiditico e non troppo costiero (per dirla in breve, vedi isg 1976, 1994). il problema è che depositi tanto recenti quanto il pleistocene superiore difficilmente si trovano in aree emerse con spessori superiori a 1-2 metri. l'italia insieme ad alcune aree del mediterraneo presenta alcune centinaia di siti con affioramenti tirreniani (ferranti et al., 2006), e, per la sua marcata mobilità sismotettonica è una delle poche aree al mondo dove alcuni affioramenti di origine marina ascrivibili al pleistocene superiore si trovano con spessori superiori ai 10-15 metri. uno di questi è quello della località il fronte fig. 1 alcuni degli autori al lavoro nella sezione "il fronte di taranto". some authors working on the outcrop “il fronte taranto section". per cui c'è probabilità che nel mar piccolo e nei suoi bordi il sollevamento sia assai più tardo e meno intenso, tale da consentire la sedimentazione marina fino all'inizio o a una parte del tarentiano e la sua emersione solo dopo la sedimentazione della panchina a strombus bubonius. i primi risultati, per ora del tutto preliminari, sullo studio in atto alla sezione del fronte esposta nel mar piccolo di taranto, indicano che la parte immediatamente sottostante alla panchina è di età tirreniana (datazioni uranio torio effettuate su cladocora in posizione vitale su peliti) (fig.2). che queste peliti, sulla base di foraminiferi e nannofossili si sono depositate nel pleistocene medio. il tutto è confermato dalla magnetostratigrafia. nella porzione pelitica del pleistocene medio sono presenti due livelli di tefra ed una laminite che potrebbe essere un sapropel. lo spessore che affiora è circa 12 metri. moltissime analisi sono in atto e altre verranno intraprese prima di proporre questo sito come potenziale gssp per il piano tarentiano. lo studio preliminare biostratigrafico colloca la sezione stratigrafica “il fronte” al di sopra della scomparsa di gephyrocapsa omega e di r. asanoi. la presenza di p. lacunosa è costante lungo tutta la sezione. in termini di schemi biozonali parliamo di zona mnn 19f di rio, raffi e villa 1990. ma considerando le eta' dei diversi eventi citati ci 37lo studio della sezione “il fronte” per la definizione ... troviamo in una fascia d'eta' compresa tra 0.577 ma (lo g. omega) e 0.430 ma (lo p. lacunosa). sulla base di queste osservazioni il sapropel individuato a 4 m circa potrebbe corrispondere al sapropel s12 (483 ka secondo lourens et al., 1996). dal punto di vista paleoambientale tutti i campioni osservati sono di ambiente profondo (tale da permettere la presenza di una associazione a nannofossili calcarei in situ, tranne gli ultimi 3 campioni in cui l'associazione e' completamente rimaneggiata. riferimenti bibliografici belluomini g., caldara, m., casini c., cerasoli m., ma n f r a l., ma s t r o n u z z i, g., pa l m e n t o l a g., sanso' p., tuccimei p., vesica p.l., 2002. the age of late pleistocene shorelines and tectonic activity of taranto area, southern italy. quaternary science reviews 21, 525 547. cita m.b., castradori d., 1994. workshop on marine sections from the gulf of taranto (southern italy) usable as potential stratotypes for the gssp of the lower, middle and upper pleistocene. il quaternario 7(2), 677-692. cita m.b., capraro l., ciaranfi n., di stefano e., marino m., rio, d., sprovieri r., vai g.b., 2006. fig 2 coralli di cladocora coespitosa affioranti nella sezione "il fronte di taranto". cladocora coespitosa corals outcropping from "il fronte taranto section". calabrian and ionian: a proposal for the definition of mediterranean stages for the lower and middle pleistocene. epidodes 29, 107 114. dai pra g. & stearns c. e., 1977. sul tirreniano di taranto. datazione su coralli con il metodo th230/u234. geologica romana, 16, 231-242. ferranti l., antonioli f., amorosi a., dai prà g., mastronuzzi g., mauz b., monaco c., orrù p., pappalardo m., radtke u., renda p., romano p., sansò p., verrubbi v. (2006). elevation of the last interglacial highstand in italy: a benchmark of coastal tectonics. quat. int. 145-146, 30-54. hearty p.j., dai pra g., 1992. the age and stratigraphy of middle pleistocene and younger deposits along the gulf of taranto (southeast italy). journal of coastal research 8, 882903. issel a., 1914. lembi fossiliferi quaternari e recenti nella sardegna meridionale: accademia nazionale dei lincei, ser. 5, 23, 759770. italian commission on stratigraphy, 2002. lourens l.j., antonarakou a., hilgen f.j., van hoof a.a.m., vergnaud-grazzini c., zachariasse w.j., 1996. evaluation of the plio-pleistocene astronomical timescale. paleoceanography 11, 391413. maiorano p., e marino m., 2005. calcareous nannofossil bioevents and environmental control on temporal and spatial patterns at the early-middle pleistocene. marine micropaleontology 53 (2004) 405422 rio d., raffi i., villa g., 1990. pliocene-pleistocene calcareous nannofossil distribution patterns in the western mediterranean. in: kastens, k.a., mascle, j., et al. (eds.), proc. odp, sci. res. 107. college station, texas, pp. 513533. v a i g.b., 2007. a history of chronostratigraphy. stratigraphy 4, 2/3, 83-97. vai g.b., & martini i.p., (eds), 2001. anatomy of an orogen: the apennines and adjacents mediterranean basins. kluwer academic publishers, 636 p. vai g.b., 1996. revisione critico-storica dei piani marini del quaternario. miscellanea, serv. geol. d'italia, 179 p., roma (coll. g. pasini). 38 ms. ricevuto il 2 aprile 2008 testo definitivo ricevuto il 17 aprile 2008 ms. received: april 2, 2008 final text received: april 17, 2008 f. antonioli et al. amq 34(2) 277-291 rettig et al def 1col2.pdf the pleistocene evolution and reconstruction of lgm and late glacial paleoglaciers of the silisia valley and mount raut (carnic prealps, ne italy). lukas rettig1, giovanni monegato2, paolo mozzi1, manja žebre3, luigi casetta4, michele fernetti4, renato r. colucci5 1dipartimento di geoscienze, università di padova, padova, italy. 2cnr istituto di geoscienze e georisorse, padova, italy. 3geološki zavod slovenije, ljubljana, slovenia. 4dipartimento di matematica e geoscienze, università di trieste, trieste, italy. 5cnr istituto di scienze polari, venezia-mestre, italy. corresponding author: g. monegato <giovanni.monegato@igg.cnr.it> abstract: small, peripheral mountain glaciers that remained independent from the large ice-streams throughout the pleistocene glaciations represent an important source of paleoclimatic information in the european alps. here, we present new evidence on the evolution of the silisia valley and paleoglaciers on the northern side of mount raut (carnic prealps, ne italy). the area is characterized by the presence of a variety of sediments and landforms, among them two generations of conglomerates and several deposits of glacigenic origin. the conglomerates are related to the infill and subsequent incision of the silisia valley during plio (?)-pleistocene times, whereas most of the glacigenic deposits can be ascribed to glacier advances during the last glacial maximum (lgm) and following late glacial stadials. during the lgm, the glacial system extended from the headwalls of mount raut (2026 m a.s.l.) down to an elevation of 440 m, and had an equilibrium line altitude (ela) of 1260 m (accumulation-area-balance ratio method aabr). assuming present-day amounts of precipitation, this corresponds to a mean summer air temperature (msat) depression of 8.5 or 9.4°c (� =±2.2°c), when compared to two recent (1960-1990) climatic records in the area. two phases of glacier stabilization during the late glacial were inferred from frontal moraine systems at higher elevations. during the first one, the glaciers had an ela of 1590 m (corresponding to an msat lowering of 6.2 or 7.1°c), whereas at the second one the ela was at 1740 m (msat lowering of 5.3 or 6.1°c). our results allow to better understand the long-term pleistocene evolution of this sector of the south-eastern alps, probably driven by the interplay between climatic fluctuations and phases of tectonic uplift. we further provide new insights on paleoglaciers of the last glacial cycle that may help in the validation of regional climatic models. keywords: last glacial maximum, carnic prealps, palaeoglacier reconstruction, equilibrium line altitude, conglomerates. available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 34 (2), 2021, 277-290 1. introduction the reconstruction of the alpine glacier network during the late pleistocene glaciations has been attempted several times through geomorphological evidence coupled with chronological data (penck & brückner, 1901-1909; castiglioni, 1940; van husen, 1987; ehlers & gibbard, 2004). alpine-scale models of the last glacial cycle were recently performed (jouvet et al., 2017; seguinot et al., 2018), but in several sectors the results are not consistent with the geomorphological evidence. because of their location at the boundary between the mediterranean and continental europe, the alps show a high climate variability (e.g., beniston, 2005; isotta et al., 2014) and are affected by a wide range of air flows and humidity conditions, as sectors of the chain face a continental-type climate and others maritime-type conditions (beniston, 2006). for this reason, large-scale modelling studies need to be tested in selected areas through paleoclimatic proxies to account for these regionally-varying climatic conditions. due to their complex geomorphological and geological structure (dal piaz et al., 2003), the external sectors of the alps are particularly characterized by a large diversity of climatic environments (ivy-ochs et al., 2021). a better knowledge of the pleistocene history of these areas can help to understand the direct relationships between climate change, landscape evolution and the development of glaciers during the cold periods. during the last glacial maximum (lgm), the alps hosted the largest ice cap in europe outside the british and scandinavian ice sheets (hughes et al., 2016; clark et al., 2021 and references therein). in the pre-alpine belts along the southern side of the alps, however, also several small and isolated glaciers developed during the lgm (e.g., carraro & sauro, 1979; baratto et al., 2003; cucato, 2007; forno et al., 2010; monegato, 2012). thanks to their relatively simple geometry, small glaciers permit accurate estimates of their equilibrium line altitude (ela) that integrate field data with numerical ap https://doi.org/10.26382/amq.2021.17 rettig l. et al. proaches of glacier reconstruction (pellitero et al., 2015, 2016). for large and interconnected valley glaciers, on the other hand, ela calculations are still problematic and can only work with models involving the whole mountain range (kuhlemann et al., 2008; višnjević et al., 2020), but without detailed field assessments. as the ela is a parameter that reflects not only local settings but also the regional climate in glaciated areas, its calculation for specific glaciers provides relevant information for inferring robust paleoclimatic reconstructions (e.g., bacon et al., 2001; spagnolo & ribolini, 2019; rea et al., 2020). the present work shows, for the first time, the distribution of quaternary deposits on the northern side of mount raut (carnic prealps). due to its location, close to the friulian piedmont plain, this area is specifically interesting for evaluating the influence of local meteorological factors, such as southerly moisture sources, on the evolution of former glaciations. through mapping and description of the sedimentary units, both the longer -term pleistocene evolution of the area and specifically the extent of paleoglaciers during the lgm and two late glacial stages are reconstructed. the calculated ela values of these glaciers are then used to estimate paleoclimatic parameters for the carnic prealps and to compare them with other regional climate proxies. 2. geomorphological and geological setting the carnic prealps (south-eastern european alps) comprise the drainage basins of the cellina, meduna and arzino streams and reach their maximum elevation in the western sector (cima dei preti, 2703 m a.s.l.). mount raut is located on the southern fringe of the carnic prealps and reaches an elevation of 2026 m (fig. 1). its northern and eastern sides are included in the meduna catchment, while the south-western slope drains towards the cellina catchment. the northern side of mount raut has three major narrow valleys, namely: valine, basson and val bassa (fig. 2). all of them are characterized by ephemeral surface runoff because of the karstic landscape (carulli et al., 2000, 2006). they are tributary valleys of the silisia valley, nowadays partially drowned by the artificial ca’ selva lake. pre-dam 1:25,000 scale topographic maps show that the presently submerged terminal tracts of the valine and basson valley were quite large and flat, with fluvial terraces driven by the incision of the silisia stream. the valley heads are characterized by large (2.25 and 1.5 km2, respectively) and gently dipping plateaus, located above 1400-1500 m and surrounded by the summit crest of mount raut. to the west, the morphology is dominated fig. 1 topographic overview of the mount raut, the silisia valley and its location within the south-eastern alps. for reference, also the extent of some following figures in the paper (figs. 2, 6, and 7) is marked here. the underlying dem was derived from the geoportal of regione autonoma friuli venezia giulia (http://irdat.regione.fvg.it). 278 the pleistocene evolution of the silisia valley and mount raut (carnic prealps) by the towering shape of mount castello (1923 m) and minor peaks towards the clautana saddle (fig. 1). in this upper sector of the silisia catchment, valleys are narrow and deeply incised. the northern side of the silisia valley comprises the steep walls of mount dosaip (2062 m) and minor and low-elevated peaks. the southern slope of the mount raut is characterized by 800 to 1200 m high walls dominating the nearby friulian piedmont plain. the bedrock in the area of the mount raut consists mainly of jurassic limestones (calcari grigi and vajont limestone) overlying late triassic (norianrhaetian) dolostones of the friulian carbonate shelf (dolomia principale). carnian dolostones (monticello formation) crop out in the hangingwall of the e-w trending, south-verging silisia thrust (fig. 2; carulli et al., 2000). the quaternary deposits are widely distributed and have been mapped only at scales from 1:50,000 to 1:100,000 in the general geological maps of the area (zenari, 1929; carulli et al., 2000). more detailed studies are lacking for the silisia valley and the mount raut, and also the drainage basin of the meduna is poor in description about the quaternary succession. only the fig. 2 simplified geological map of the northern side of mount raut with locations of quaternary deposits and moraine ridges. boundaries of geological units and the location of the fault line are from carulli et al. (2000). 279 lacustrine deposits of lake redona (venzo et al., 1975; cavallin & martinis, 1981) and the complex quaternary succession in the lower valley reach (carraro & polino, 1976; venturini, 1985; venturini et al., 2013; monegato & poli, 2015) have been studied. as a result of this lack of detailed data, the extent of the mount raut paleoglacier during the lgm is still debated. in the early map by castiglioni (1940) only a small glacier, just reaching the bottom of the silisia valley, is shown and the meduna valley was considered ice-free. this interpretation was maintained in the most recent climex map (vai & cantelli, 2004). gortani (1959) reported a larger glacier in the silisia valley, merging to that flowing down the meduna trunk valley. a similar large ice extent, including the meduna valley, was reported in the map by ehlers & gibbard (2004), following the review by castiglioni (2004). the area is presently characterized by a quite high precipitation with constant contribution from all seasons (crespi et al., 2018). the 1961-2000 climatology at barcis, according to the local meteorological observatory (www.meteo.fvg.it, last accessed july 9th, 2021), presents mean annual precipitation (map) equal to 2197 mm water equivalent (w.e.), with january the driest month (116 mm w.e.) and october the wettest (287 mm w.e.). the impact of moist southerly winds (scirocco) in the carnic pre-alpine sector generally leads to longlasting orographic precipitation and intense convective systems in all seasons, representing the main driver for such high map (colucci et al., 2021). recent (20042020) mean annual air temperature (maat), calculated for the weather station of pala d’altei (www.meteo.fvg.it, last accessed july 9th, 2021), located at 1528 m about 8.5 km to the south-west, is equal to 6.4°c, with january and february being the coldest months (-1.5°c) and july the warmest (14.8°c). a longer climatological record has been reconstructed by colucci & guglielmin (2015) for the mount canin/kanin (julian alps) at an elevation of 2200 m, representing an important regional source of temperature data that precedes the most recent climatic warming since the 1990s. 3. methods field surveys in the study area were carried out between 2018 and 2021 to describe and map the distribution of geomorphological features and quaternary deposits along the northern side of mount raut and in the silisia valley. the mapping procedure was performed on regional topographic maps at a scale of 1:5000, with the support of lidar data (grid resolution of 1 m, survey carried on 2006) derived from the geoportal of regione autonoma friuli venezia giulia (http:// irdat.regione.fvg.it). older topographic maps (igm at a scale of 1:25,000) allowed reconstructing the topography of the silisia valley prior to the construction of the dam at ca’ selva. based on these elevation data and on the geomorphological and sedimentological evidence found during field work, reconstructions of paleoglacier geometries and elas were carried out using recently developed toolboxes within esri arcmap v. 10.7 (pellitero et al., 2015, 2016). glacier surfaces were reconstructed along flowlines, extending from mapped moraine ridges or the lower limits of till outcrops up to the accumulation areas on the plateaus at the valley head. initially, a subglacial shear stress of 100 kpa, characteristic of the base of alpine glaciers, was applied to the whole length of these flowlines (paterson, 1994; brædstrup et al., 2016; pellitero et al., 2016). this value had to be additionally modified in some parts of the catchment, with the aim of better tuning the reconstructed glacier surface with the geomorphological evidence. generally, the low-lying valley mouths required a lower shear stress (50 kpa) to yield realistic ice-thicknesses, which is compatible with the glacier overriding thicker sediment fills with low yield strength at these locations (thorp, 1991; iverson et al., 2003). for the steep glacial troughs of the basson and bassa valleys, an additional f-factor adjustment, which is a function of the glacier width and thickness, was applied to account for lateral drag exerted by the valley walls (nye, 1952; benn & hulton, 2010; pellitero et al., 2016). from the reconstructed glacier surfaces, elas were calculated using both the accumulation-areabalance ratio (aabr) and the accumulation-area-ratio (aar), as frequently applied in studies on paleoglaciers in the european alps (e.g., federici et al., 2012; monegato, 2012; hofmann et al., 2019; spagnolo & ribolini, 2019). for the aabr-method, balance ratios of 1.56 (representing a global median value) and 1.29 (representing the median value for modern alpine glaciers) were chosen (oien et al., 2021). for the aarmethod, the global median value of 0.58 was initially used (rea, 2009; oien et al., 2021), but elas were also calculated for ratios of 0.5, 0.65, and 0.7 to test for the sensitivity of reconstructed elas on the choice of different aars. to facilitate paleoclimate interpretations, present rettig l. et al. fig. 3 mean summer air temperature (msat) at canin (19612020), baldas (mount resettum) and malga valine (mount raut) (2010-2020) from colucci and guglielmin (2015) and www.meteo.fvg.it (last accessed, july 9th 2021). the data demonstrated the close statistical correlation between the three records. 280 the pleistocene evolution of the silisia valley and mount raut (carnic prealps) day temperature and precipitation in the study area were reconstructed first. this included the 1961-2000 map in barcis and the 2010-2020 mean summer air temperature (msat) at the local weather stations of malga valine-mount rest (1346 m) and baldass-mount resettum (1817 m), the latter located ca. 6 km to the west of mount raut (for location of weather stations see fig. 1). in order to obtain a msat for the climatic period 1961-1990, the values from the local weather stations were then corrected using the canin record from colucci & guglielmin (2015). this was possible, as the correlation between temperatures at the local weather stations and the canin is statistically significant (for baldass r=0.95 and for malga valine r=0.87; fig. 3). the calculated 2010-2020 msat at canin is 2.2°c higher than the average between 1961 and 1990, therefore this value was added to the 2010-2020 msat of baldass and malga valine to obtain the 1961-1990 value. the results from elas calculation were then used to reconstruct the paleoclimatic conditions during the lgm and late glacial stadials. at first, paleoprecipitation was assumed to be equal to present-day records and summer temperatures at the ela were calculated using the following equation from ohmura & boettcher (2018): pa =5.87 tsum² + 230 tsum + 966 (1) s.e. =648 mm where pa is annual precipitation (mm) and tsum is summer (jja) air temperature (°c). applying a summer environmental lapse rate of 0.65°c 100 1 m, representative for the greater alpine region (rolland, 2003; rubel et al., 2017), we calculated the temperature differences from the modern local weather stations. this procedure was equally repeated for different precipitation scenarios, ranging from -30% to +30% of the present-day value. when comparing elas of paleoglaciers to present climatic conditions, all calculated values were assumed to represent environmental elas (envela; žebre et al., 2020). the envela is the theoretical altitude at which a glacier can form and does not consider the effects of shading, avalanching, snow drifting, glacier geometry or debris-cover (anderson et al., 2018). in the alps it was found to be ~75-150 m higher than the regional effective ela (effela; žebre et al., 2020), which accounts for these topographic effects when averaged over a longer climatic period (e.g., 15-30 years). 4. the pleistocene deposits in the silisia valley along the silisia valley, and on the northern side of mount raut, pleistocene deposits are scattered; they can be lithologically grouped into breccias, gravels, conglomerates and diamictons. some of the deposits recorded in the old geological map (zenari, 1929) are presently drowned by the ca’ selva lake. many outcrops are visible along road cuts. an overview about the areas mentioned in the description and the location of the deposits is given in a photograph in fig. 4a and in a cross-profile through the silisia valley (fig. 5). 4.1. breccias, gravels and conglomerates conglomerates are located in several sectors of the valley. the cementation of these deposits is strong and some of them show karstic dissolution structures (fig. 4b). the conglomerates are made of clastsupported gravels, crudely bedded to horizontally bedded, and characterized by sub-rounded clasts of limestones, dolostones and cherts (red and black), pointing to a provenance from the upper catchment of the silisia valley. lateral interfingering with angular breccias is visible and suggests the occurrence of local alluvial or talus deposits. conglomerates mainly crop out in three locations: chiavalot, sarazin ridge, and selva (see figs. 2, 4a and 5). in the chiavalot area, conglomerates are about 40 m thick, with the basal boundary on the bedrock at 900-910 m, and the rim of the chiavalot cliff at 950 m, around 400 m above the lake. the deposits are karstified and deeply cut by local stream incisions. on the sarazin ridge, the conglomerate and breccias are visible along the roadcut (fig. 4c), clasts of conglomerates (i.e., the unit preserved at chiavalot) are included indicating the erosion of an older conglomerate body. the topmost conglomerates are at 775 m and the basal boundary can be observed at ca. 670 m, suggesting the presence of a former valley fill with an overall thickness of around 100 m. the breccia/conglomerate body is locally weakly cemented and intersected by several joints that can be likely ascribed to tectonic activity. similar deformed breccias are located at about 610 m, along the main road at the southern side of the lake. a small outcrop of conglomerates is located on the southern tip of the ridge separating the village of selva from the valley gorge downstream of the dam (fig. 2). this deposit is only a few meters thick and lays on top of the bedrock on the western slope of the ridge. upstream the present lake, at stua, a succession of gravels and sandy gravels crops out (d’agostina, 2010); these are bedded and gently inclined (10-20°) downstream and show a thickness of about 10 m. they are interpreted as related to a fan delta body. 4.2. diamictons along the road flanking the southern side of the ca’ selva lake, sub-rounded boulders are common and outcrops of diamicton, matrix-supported, with striated clasts occur frequently. clasts are sub-angular to subrounded and clast petrography is mostly made of dolostones and limestones, with angular chert clasts (red and black). because of their sedimentary properties, these deposits were ascribed to glacial deposition. in detail, the westernmost outcrop of these diamictons along the lake corresponds to the moraine of case val bassa at the elevation of 520 m. the moraine ridge is ca. 300 m long and located on the left side of the valley outlet between elevations 575 m and 500 m. it contains mostly sub-angular to sub-rounded, large dolostone and limestone boulders, few of which show striations. the overall thickness of the deposit is about 25 m. a similar diamicton crops out at the outlet of the basson valley at an elevation of ca. 500 m (fig. 4e). it is also associated to a left lateral moraine, that is well preserved close to the lake and partly covered by talus. the right moraine flank has been remodelled and a cluster of 281 rettig l. et al. fig. 4 plate of pictures taken during field work. a. view across the lake ca’ selva towards the valley mouths of the valine (in the foreground), basson and bassa (hidden). visible are also the chiavalot cliff and the sarazin ridge, two locations at which thick conglomerate bodies are cropping out. b. strongly cemented conglomerate from the chiavalot. c. stratified conglomerated along the roadcut at the sarazin ridge. d. the glacial diamicton at case staleros. e. glacial diamicton at the mouth of the basson valley. f. view towards the upper valine catchment and the malga valine, where the terminal moraine is marked by red dashed line. g. the terminal moraine ridges at casera valine with a large limestone erratic in the foreground situated on the moraine crest. h. fluted moraines in the upper valine catchment. 282 big boulders is now partially drowned by the lake (d’agostina, 2010). as well, in the lower reach of the valine valley, matrix-supported diamicton, with big boulders and mostly sub-angular to sub-rounded dolostone and limestone clasts, crops out close to the sarazin ridge, at about 600 m. here, however, it is not associated to a clear landform, as it is the case for the outlets of basson and bassa valleys outlets. a thick unit of diamicton is located at case staleros, east of the ca’ selva dam, where it lays on top of the bedrock at an elevation of 530 m. it consists of matrix-supported diamicton, embedding big boulders and striated clasts (fig. 4d). clasts are angular to subrounded; clast petrography indicates dominant dolostones and limestones (mostly sub-rounded), with minor amounts of cherts. the matrix is sandy and the deposit is normally consolidated and weakly and spotty cemented. the visible thickness of the deposit is about 25 m and it is associated to the moraine ridge of stavoli staleros. downstream from this moraine along the silisia valley, no glacial deposits have been observed. several clusters of moraine ridges can also be recognized in the upper sectors of the basson and valine narrow valleys. a wide set of arch-shaped terminal moraines, up to 5 m high, is located in the valine valley at casera valine (1330 m) and forms a large flat area on the back (fig. 4f and 4g). the moraines are made of diamicton, mostly characterized by angular/ subangular boulders in a sandy matrix. on the back of the frontal moraines two longitudinal ridges made of boulders can be ascribed to fluted moraines on the base of their downvalley elongated morphology (fig. 4h). in the basson valley, ending with the mount raut headwall, two separated sets of moraines can be distinguished. the first set is located at 1050 m and consists of mainly of lateral moraines, while the frontal moraines are flat and have been reshaped by local drainage. the second set of moraines is located upstream in the valley between 1425 and 1600 m. these moraines are elongated lateral ridges, while the frontal sector is characterized by scattered boulders in a flat area at about 1400 m. 5. glacier reconstructions given the abundance of glacial landforms and sediments containing clast lithologies of local provenance, it can be concluded that the northern side of mount raut was covered by a glacial system that remained independent from the alpine glacier network. no dating is available for these glacial features. nevertheless, it is possible to attribute them to glacial advances during the last glacial maximum and subsequent late glacial stages, considering the absence of deep weathering and cementation that would typically characterize sediments related to prior glaciations. the only exception is the diamicton at stavoli staleros, which is interpreted as a pre-lgm glacial deposit. this is both due to its sedimentary properties (i.e., spotty cementation) and its overall position in the valley system, more than 150 m high above the present course of the silisia stream (see figs. 4a and 5). an interpretation of the staleros moraine as an lgm ice-front would require both exceedingly thick ice in the silisia valley and extremely high postglacial erosion rates, both of which are not compatible with field evidence and glacier modeling. the lgm glacial network was therefore reconstructed basing on the presence of glacial deposits and frontal moraines that are present at the outlets of the bassa, basson and valine valleys. detailed information on the reconstructed glaciers, including calculated elas for the lgm and late glacial stadials is presented in tab. 1. the elas calculated for aabrs of 1.56 and 1.29 do not show large differences, and are within the error range generally expected for ela reconstructions (oien et al., 2021). there is also a good agreement with the calculations using an aar value of 0.65, while the global median of 0.58 results in slightly higher elas. although for the smaller late glacial stages also aar values of 0.5 and 0.7 yield reasonable estimates, a change in these ratios for the lgm results in a large shift of the calculated ela (aar 0.5 =1480 m; aar 0.7 =1140 m). this is likely due to the particular hypsometry of the mount raut glacier during the lgm, with very steep and narrow valleys present in proximity to the ela. because of these potential complications, all elas in the following the pleistocene evolution of the silisia valley and mount raut (carnic prealps) fig. 5 cross-profile through the silisia valley including the major side valleys and sedimentary units discussed in the text. for the location of the profile see fig. 1. 283 284 rettig l. et al. paragraphs and in the climatic interpretations are reported using the aabr-method with the global median value of 1.56 (oien et al., 2021). 5.1. the mount raut glacier during the last glacial maximum during the lgm, the glacial system of the mount raut had an ela of 1260 m and covered an area of approximately 7 km2 with glacier tongues extending into all three main valleys on its northern side (fig. 6). ice was accumulating on the high-altitude plateaus of the basson and valine catchments up to an altitude of ca. 2030 m. a smaller accumulation area was also located at the head of the bassa valley, although this tributary probably received part of its ice through transfluence from the neighboring basson catchment. from the plateaus, the ice was flowing northwards, constrained within the narrow glacial valleys. in the bassa valley, the maximum ice extent during the lgm is clearly delineated by a frontal moraine ridge, situated at an altitude of 520 m, indicating that the glacier advance stopped just before reaching the e-w trending silisia valley. in contrast, the glacier tongue coming from the basson valley advanced further downstream, as shown by the presence of glacial diamicton and scattered boulders around the flat valley mouth. the larger extent of this tributary can be explained both by the high elevations of the basson plateau, and by the fact that it received additional input from the valine catchment further downstream. the infilling of the valley mouth with glacier ice likely led to a damming fig. 6 the reconstructed glacial system of mount raut during the lgm (ela =1260 m). of the silisia stream, a hypothesis which is corroborated by the presence of fan delta deposits further upstream (d’agostina, 2010). in the lower valine valley, clear geomorphological evidence in the form of a frontal moraine is lacking. however, scattered occurrence of glacial deposits and large boulders at an altitude of 500-600 m suggests that also this tongue extended down towards the valley mouth. the frontal moraine system of this lobe might presently be covered by the ca’ selva lake or, alternatively, might have already been eroded by the silisia stream before the construction of the dam. in addition, a smaller lgm glacier developed in the cirque northwest of mount rodolino (fig. 6), which remained independent from the mount raut glacial system. however, no clear indication of its frontal position was found, which is at least partly due to the steepness of the terrain in this area. 5.2. the valine and basson glaciers during the late glacial after the lgm, the glaciers of the mount raut retreated into the higher parts of their catchments. evidence for phases of glacier stabilization or re-advance during this time can be found as series of moraines both in the valine and the basson valleys. in the valine valley, several well-defined moraine ridges are located at an elevation of around 1330 m, delimiting a small glacier (surface area of ca. 0.9 km²) with an ela of 1570 m (fig. 7a). due to its higher catchment, the basson glacier must have still had a larger extent during this time, with its front potentially stabilizing at an altitude of ca. 1050 m. although patches of glacial deposits and moraine ridges were found here in a lateral position, an evident frontal system is lacking, and it is not clear if these deposits relate to a distinct late glacial advance or can be ascribed to the downwasting of the lgm glacier. conversely, in the basson valley a second set of moraines can be found stretching down to an altitude of ca. 1400 m, indicating a later phase of glacier stabilization during the late glacial. the basson glacier reconstructed for this stage covered an area of ca. 1.2 km2 and its ela was calculated at 1740 m (fig. 7b). at the same time, the glacier in the valine must have almost entirely disappeared or was preserved only as a small niche glacier or firn field, which could also explain the absence of depositional features on the upper valine plateau. 6. discussion 6.1. the pleistocene evolution of the silisia valley and the mount raut paleoglaciers the southern sector of the meduna catchment has been affected by important drainage changes since the messinian, and during the pleistocene, several alluvial sedimentary units were deposited in the lower reach of the valley (monegato & poli, 2015). the tectonic evolution of the south-eastern alps (poli et al., 2009, 2021) has driven these changes. in this perspective, it can be assumed that also the two conglomerate units, at chiavalot and sarazin, are linked to the evolution of the silisia valley and the ongoing incision and infill during plio(?)-pleistocene time. the differences in cementation and weathering degree, also considering the presence of conglomerate pebbles in the sarazin body, then point to different sedimentation of these units in events that pre-date the last sedimentation phase related to the lgm and late glacial. considering the difference in elevation between chiavalot and sarazin of more than 200 m, and the location of the chiavalot in the footwall of the silisia thrust, the progressive incision of the silisia stream probably felt the effect of the general uplift in this sector of the carnic prealps, which is related to the frontal thrusts of the eastern southalpine south-eastern alpine chain (poli et al., 2009, 2021). in this respect, the silisia valley and the mount raut lie on the hanging wall of the periadriatic thrust (carulli et al., 2000), while the lower meduna valley sedimentary stack is located between the periadriatic thrust and the m. jouf-maniago thrust system. three tectonic phases were described in the frontal sector of the carnic prealps (caputo et al., 2010; monegato & poli, 2015), pointing to a potential enhancement of fluvial incision during uplift phases, especially along the major cataclastic belts related to the tectonic structures. the infilling phases of such narrow tributary valleys can be ascribed to glacial damming or 285 the pleistocene evolution of the silisia valley and mount raut (carnic prealps) tab. 1 characteristics of the reconstructed glaciers on the northern side of mount raut for the lgm and two late glacial stages, including elas calculated for several aabrs and aars. in red, hypothetical reconstructions due to lack of geomorphological evidence landslide damming. in this perspective, the chiavalot unit represents the oldest sedimentary infill of the valley, which can be linked to the karstified conglomerates of the lower meduna valley (monegato & poli, 2015). the deepening of the valley of about 200 m occurred before the deposition of the sarazin unit and suggests that an uplift phase likely took place in the lower pleistocene. the difference in elevation of about 170 m from the basal boundary of the sarazin unit to the lgm deposits also indicates this post-depositional uplift. this influenced the deep incision downstream of the dam, which led to the abandonment of the path through selva and the preservation of the glacigenic deposits of staleros. a similar deepening characterizes also the meduna valley, which was later filled by lacustrine deposits (venzo et al., 1975; cavallin & martinis, 1981). the staleros unit itself can most likely be ascribed to a middle pleistocene ice advance, even if no chronological data are available. in the lower meduna valley, old alluvial terraces (monegato & poli, 2015) may represent its outwash deposition. during the lgm, glaciers in the valine, basson and bassa catchments advanced for the last time beyond their valley mouths, leading to the deposition of frontal moraines and glacial sediments and at least temporarily to a damming of the silisia valley upstream. the well-preserved fluvial terraces of faidona (cavallin & martinis, 1981), at the confluence with the meduna valley, can probably be ascribed to deposition by meltwaters originating from the glacial system during this time. from the position of the moraine ridges, however, it can clearly be established that the raut paleoglacier itself never merged with the glacial system of the meduna valley, as it was sometimes reported in previous studies (gortani, 1959; ehlers & gibbard, 2004). regionally, the first culmination of the lgm advance has been dated to around 26.5 to 23 cal ka bp, with a later pulse occurring at 22 cal ka bp (tagliamento endmoraine system, monegato et al., 2007; fontana et al., 2014). this later stage also corresponds to the phase of maximum aggradation in the meduna alluvial fan (avigliano et al., 2002). although no numerical dating is available for the mount raut, we hypothesize that the advance of the glacial system during the lgm probably took place during the same time span, considering the similar climatic setting to the meduna and tagliamento catchments. following the downwasting of the lgm glaciers, two distinct advances of the basson and valine valley glaciers occurred during the late glacial. such stages of stabilization have been equally recognized in parts of the carnic alps and julian prealps (discenza, 2004; colucci et al., 2014) and the chiampon-cuel di lanis ridge (monegato, 2012). in the latter case, these glaciers exhibit an ela ca. 250 to 350 m higher with respect to the lgm, which matches the calculations for late glacial stage 1 (lg1) in the valine (ela raising of ca. 330 m). even if this may point to a common climatic driver for the glacier advance, a detailed chronology for the ice -decay in the south-eastern alps is still lacking, which hampers comparisons between different mountain ranges or a correlation to one of the established late glacial stadials in other sectors of the alps (e.g., ivy-ochs et al., 2008). rettig l. et al. fig. 7 the valine and basson glaciers during the late glacial. a. late glacial stage 1 (ela =1570 m). b. late glacial stage 2 (ela =1740 m). 286 several small mountain glaciers remained independent from the large alpine ice-streams throughout the late pleistocene cold phases, including the last glacial maximum, one of which was located on the northern side of mount raut (carnic prealps, ne italy). the reconstruction of these glaciers and their elas reveals important information about the past climate. our investigation shows that the lgm glacial system of the mount raut covered an area of ca. 7 km². its ela (aabr) was calculated at 1260 m. assuming levels of precipitation similar to today, an lgm msat depression of 8.5 or 9.4°c (� =±2.2°c) was calculated in re6.2. paleoclimate reconstructions the calculated ela of 1260 m for the lgm glacial system is among the lowest reported for the southern fringe of the alps so far. it corresponds best with those calculated from other areas in the south-eastern part of the range, such as the julian prealps (elas =11281190 m, monegato, 2012), or the trnovski gozd in the slovenian dinaric mountains (ela =1240, žebre et al., 2014). already at mount grappa, ca. 75 km further west, elas are reported to be around 150-200 m higher than at mount raut (carraro & sauro, 1979; baratto et al., 2003). the values increase even further towards the central southern alps (ela =1535 m; forno et al., 2010) or the maritime alps (ela =1850 m; federici et al., 2012), indicating that an east-west ela-gradient probably prevailed along the southern fringe of the alps during the lgm. present (2010-2020) msat in baldass and malga valine, which are closer in respect to the pala d’altei station, are at 12.6°c and 14.8°c, respectively. given the ela of 1260 m, and assuming present-day precipitation, our calculations suggest that, compared to the period 1961-1990, msat in the mount raut area was depressed by around 9.4°c or 8.5°c during the lgm, by 7.1 or 6.2 °c during the lg1, and by 6.1 or 5.3°c during the lg2, respectively (� =±2.2°c). the results for the lgm are consistent with regional models of atmospheric circulation (kuhlemann et al., 2008) and also with chironomid-based july temperatures reconstructed at lago della costa (euganean hills, samartin et al., 2016). with different precipitation scenarios (±30% of the present-day value, see tab. 2, 3, 4), msat depressions vary between 6.2°c (7.0°c, respectively) and 11.6°c (10.8°c, respectively). with a further reduction in precipitation, reconstructed temperatures are not compatible anymore with the aforementioned calculations from other proxies. this indicates that the lgm climate in the south-eastern alps was very likely characterized by high precipitation throughout the whole lgm. these high amounts of precipitation, especially during autumn and winter (spötl et al., 2021), allowed glaciers to expand to lower elevations as in other parts of the southern alps and today it still ensures the preservation of very small glaciers in parts of the carnic and julian alps (colucci et al., 2021). 7. conclusion new evidence for the pleistocene evolution of mount raut and the neighboring silisia valley is presented in this study, basing on mapping and description of quaternary sediments and landforms. detailed studies concerning the quaternary deposits and landforms in the area were previously still lacking. two bodies of conglomerates were found and they have been related to the recurring infill and incision of the silisia valley during plio(?)-pleistocene times, probably driven partly by climatic fluctuations and partly by tectonic uplift phases of the south-eastern alps. series of moraine ridges and glacigenic deposits are mainly related to glacier advances during the lgm and following late glacial stages. in the south-eastern part of the european alps, the pleistocene evolution of the silisia valley and mount raut (carnic prealps) tab. 4 msat depression calculated for the late glacial stage 2, assuming different map scenarios. tab. 2 msat depression calculated for the lgm, assuming different map scenarios. tab. 3 msat depression calculated for the late glacial stage 1, assuming different map scenarios. 287 spect to two recent (1960-1990) climatic records in the area. during the late glacial, glaciers were confined in the upper parts of their catchments, intermitted by two distinct phases of glacier stabilization, the first at which glaciers had an ela of 1590 m (corresponding to an msat lowering of 6.2 or 7.1°c) and the second with an ela of 1740 m (msat lowering of 5.3 or 6.1°c). these calculations are generally in line with regional circulation models, indicating that glaciers in the south-eastern alps received high amounts of precipitation throughout the lgm. however, further research is needed to better understand the paleoclimatic evolution in the 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(1929) note illustrative della carta geologica delle tre venezie foglio “maniago”. ufficio idrografico regio magistrato acque di venezia, padova. rettig l. et al. ms. received: july 16, 2021 revised: october 21, 2021 accepted: december 9. 2021 available online: 23 december 2021 290 imp.bonci& geositi e gssp le attività del dipartimento difesa della natura dell'apat luciano bonci, tiziana mezzetti & gabriella rago apat dipartimento difesa della natura servizio aree protette e pianificazione territoriale abstract: l. bonci, t. mezzetti & g. rago, geosites and gssp apat's activities. the italian agency for environmental protection (apat) is the italian body responsible for the protection of the environment and for the collection and management of environmental data, and develops an important activity on geosites. apat is setting up a working group within geological coordination committee between state, regions and autonomy provinces (comitato di coordinamento geologico tra lo stato, le regioni e le province autonome c.c.s.r.) to validate geosites and to insert it in the national geosites atlas, and a working group within italian commision on stratigraphy (commissione italiana di stratigrafia) to protect and to valorize the gssp. parole chiave: geositi, gssp, italia. keywords: geosites, gssp, italy. il quaternario italian journal of quaternary sciences 21(1a), 2008 75-80 premessa a seguito del ii° symposium internazionale sulla protezione del patrimonio geologico, tenutosi a roma nel 1996, si è costituito il gruppo progeo italia il cui compito principale è quello di promuovere la diffusione dell'informazione sul patrimonio geologico e la sua conservazione ed al quale hanno aderito docenti e ricercatori delle università, del cnr, dell'enea e del servizio geologico nazionale. in tale ambito è maturata l'idea di realizzare un censimento nazionale dei geositi ed il servizio geologico nazionale, anche in conseguenza del ruolo storico istituzionale ricoperto, è stato indicato quale candidato ideale per il coordinamento delle diverse iniziative che in tale ambito, a livello locale, erano già state da tempo avviate in italia. il servizio geologico nazionale curava, infatti, a livello nazionale la raccolta, gestione e pubblicazione dei dati e della cartografia geologica e geotematica, compresa quella ufficiale dello stato, realizzata ai sensi della legge 68/1960, ponendosi in qualità di organo cartografico dello stato, quale struttura tecnico scientifica centrale e di coordinamento tra la comunità scientifica e le realtà istituzionali regionali e locali. l'apat l'8 ottobre 2002, in attuazione del dettato normativo contenuto nel d.p.r. 207 del 8.8.2002, diviene operativa l'apat, l'agenzia per la protezione dell'ambiente e per i servizi tecnici. a seguito dell' art.38 del d.l.vo 300 del 30.7.1999, l'apat eredita le competenze istituzionali dell'agenzia nazionale per la protezione dell'ambiente (anpa) e del dipartimento per i servizi tecnici nazionali ed in particolare del servizio geologico e del servizio idrografico e mareografico della presidenza del consiglio dei ministri (dstn), svolgendo i compiti e le attività tecnico-scientifiche di interesse nazionale per la protezione dell'ambiente, per la tutela delle risorse idriche e della difesa del suolo. nell'ambito di questo nuovo assetto organizzativo tutte le attribuzioni proprie del servizio geologico nazionale, sono confluite all'interno del dipartimento difesa del suolo ad eccezione del progetto “carta della natura” (legge 394/91) e del progetto “tutela del patrimonio geologico” attribuiti al dipartimento difesa della natura istituendo contemporaneamente il servizio carta della natura e all'interno dell'ex servizio “parchi e risorse naturali", ora servizio “aree protette e pianificazione territoriale“, il settore “tutela del patrimonio geologico”. con questa nuova assegnazione di competenze la tutela del patrimonio geologico viene più strettamente correlata alla tutela degli altri aspetti del patrimonio naturalistico ed ambientale di cui la geologia è substrato fisico e aspetto morfologicopaesistico permanente. i geositi ed il contesto normativo “i geositi sono aree del territorio di rilevante interesse geo-morfologico e valore naturalistico, risorse non rinnovabili, ed importanti testimoni della storia della terra (w.a. wimbledon, 1995). essi rendono “peculiari” i luoghi e le aree territoriali in cui sono inseriti per i loro specifici fattori fisici, morfologici, climatici e strutturali, e necessitano pertanto di un'azione di tutela e valorizzazione affinché non vada persa per sempre traccia della storia della terra. dal punto di vista normativo il valore del patrimonio geologico culturale è stato riconosciuto sia a livello nazionale che internazionale: 76 l. bonci et al. dalla convenzione per la protezione del patrimonio mondiale, culturale e naturale adottata dall' unesco nell'ambito della conferenza generale svoltasi a parigi il 16 novembre 1972 e recepita dal nostro ordinamento con la legge 6 aprile 1977, n.184, il cui scopo è conservare il patrimonio mondiale di interesse universale eccezionale, attraverso la stesura di una lista di siti culturali e naturali (world heritage list), in particolare l'art.2 che individua nell'ambito del patrimonio naturale “i monumenti naturali costituiti da formazioni fisiche e biologiche o da gruppi di tali formazioni di valore universale eccezionale dall'aspetto estetico o scientifico, le formazioni geologiche e fisiografiche e le zone strettamente delimitate costituenti l'habitat di specie animali e vegetali minacciate, di valore universale eccezionale dall'aspetto scientifico o conservativo, i siti naturali o le zone naturali strettamente delimitate di valore universale eccezionale dall'aspetto scientifico, conservativo o estetico naturale […]”. il concetto di patrimonio geologico viene dunque a far parte del patrimonio naturale e definito in base a quanto stabilito dal documento risultante dal i° simposio internazionale per la protezione del patrimonio geologico tenutosi a digne nel 1991: “dichiarazione internazionale dei diritti della memoria della terra” come l'insieme delle risorse non rinnovabili, di valore scientifico, culturale o educativo, quali formazioni o strutture geologiche, forme del paesaggio o giacimenti paleontologici e mineralogici che permettono di riconoscere, studiare ed interpretare l'evoluzione della storia geologica della terra ed i processi che l'hanno interessata; dalla direttiva habitat del 21 maggio 1992 n. 92/43/cee relativa alla conservazione degli habitat naturali e seminaturali e della flora e della fauna selvatiche, che integra la legislazione comunitaria sulla conservazione della natura, proteggendo in un quadro unitario habitat naturali (zone terrestri o acquatiche che si distinguono per le loro caratteristiche geografiche, abiotiche e biotiche interamente naturali e seminaturali). in particolare nell'allegato i alla direttiva vengono individuati tra i vari tipi di habitat naturali di interesse comunitario “dune marittime e interne, torbiere e paludi, habitat rocciosi (grotte marine sommerse e semisommerse, campi di lava e cavità naturali, ghiacciai permanenti), ghiaioni, zone rilevanti per avere delle caratteristiche biogeografiche e geologiche particolari o uniche”; dalla convenzione europea del paesaggio firmata a firenze il 20 ottobre del 2000, ratificata e resa esecutiva in italia con la legge 9 gennaio 2006 n.14, relativa alla salvaguardia, gestione e pianificazione dei paesaggi europei, in particolare il cap.ii, art.1 lett. a, d) volto alla salvaguardia dei “paesaggi ed alle azioni di conservazione e di mantenimento degli aspetti significativi o caratteristici di un paesaggio giustificate dal suo valore di patrimonio derivante dalla sua configurazione naturale e/o dal tipo di intervento umano; l'art.5, lett.a) in cui il paesaggio viene ad assumere un ruolo fondamentale nel consolidamento dell'identità europea in quanto “componente essenziale del contesto di vita delle popolazioni, espressione della diversità del loro comune patrimonio culturale e naturale[…]”. dalla raccomandazione rec(2004)3, documento sulla conservazione del patrimonio geologico e delle aree di speciale interesse geologico adottato dal comitato dei ministri del consiglio d'europa. dall'art. 9 della costituzione della repubblica italiana riguardante la promozione e lo sviluppo della cultura e la ricerca scientifica e tecnica, e la tutela del paesaggio e del patrimonio storico e artistico della nazione; dalla legge quadro sulle aree protette l.394/1991 in particolare l'art.1 comma 2), che indica tra le finalità del regime di tutela e di gestione delle aree protette, quella della conservazione e tutela delle “formazioni fisiche, geologiche, geomorfologiche e biologiche, o gruppi di esse che abbiano rilevante valore naturalistico e ambientale”; l'art.1 comma 3 lett. a) che sottopone a regime di tutela allo scopo di evidenziarne i valori naturali e i profili di vulnerabilità territoriale le “singolarità geologiche, formazioni paleontologiche, valori scenici e panoramici, processi naturali, equilibri idraulici ed idrogeologici; dal codice dei beni culturali e del paesaggio d. lvo. 42/2004, in particolare l'art. 2 che definisce il patrimonio culturale “costituito dai beni culturale e dai beni paesaggistici […] sono beni paesaggistici gli immobili e le aree […] costituenti espressione dei valori storici, culturali, naturali, morfologici ed estetici del territorio”, l'art. 10 che identifica tra i beni culturali “le cose immobili e mobili […] che interessano la paleontologia, i siti minerari di interesse storico o etnoantropologico”, l'art. 136 che elenca tra gli immobili di notevole interesse pubblico le cose immobili che hanno cospicui caratteri di bellezza naturale o di singolarità geologica; tale elenco non ha carattere di esaustività ma vuole dare un quadro sintetico delle principali normative per la tutela del patrimonio geologico. le attività svolte e il “censimento nazionale dei geositi” l'idea di realizzare un censimento nazionale dei geositi prende corpo nell'anno 2000 attraverso l'attivazione del progetto “conservazione del patrimonio geologico italiano". il progetto diviene operativo grazie a numerosi accordi di collaborazione e convenzioni con istituti scientifici ed università tra cui (nel 2002 e 2003) quelle con il dipartimento polis centro di documentazione geositi dell'università degli studi di genova volte alla “costituzione di un inventario dei geositi italiani finalizzato alla realizzazione di una banca dati nazionale sul patrimonio geologico italiano” allo scopo di costituire un centro nazionale di raccolta sistematica di dati e metadati sui siti di interesse geologico e di fornire uno strumento per la pubblica amministrazione nella pianificazione territoriale (d'andrea, 2000; d'andrea & angelelli, 2001). le convenzioni hanno portato ad un prima individuazione e localizzazione dei geositi sull'intero territorio nazionale, ed alla realizzazione di una “carta di prima attenzione dei siti di interesse geologico in italia” presentata in occasione del 32° international geological congress (firenze 2004). nel 2005 viene pubblicato un rapporto tecnico apat, frutto della cooperazione di alcuni fra i più rappresentativi attori delle pubbliche amministrazioni, delle università e dei centri di ricerca nelle iniziative di conservazione e valorizzazione del patrimonio geologico, dal titolo “patrimonio geologico e geodiversità, esperienze ed attività dal servizio geologico d'italia all'apat ”, scaricabile dal sito apat all'indirizzo: http://www.apat.gov.it/site/itit/apat/ p u b b l i c a z i o n i / r a p p o r t i / d o c u m e n t o / r a p p o r t i _2005_51.html. lo studio sul territorio nazionale dei geositi è stato messo in relazione con il sistema di aree naturali protette (l.394/1991). dalla sovrapposizione del livello dei geositi su quello delle aree naturali protette, presenti nel sistema informativo territoriale “gis natura” del mattm, si evince una forte concentrazione dei siti geologici sul territorio al di fuori del perimetro delle aree suddette. al fine quindi di conservare e valorizzare il patrimonio geologico su tutto il territorio nazionale, occorre far rientrare i geositi nella pianificazione territoriale. in vista di ciò, nell'ambito di una collaborazione con il ministero per i beni e le attività culturali (mibac), sono state fornite le informazioni contenute nella banca dati, per l'inserimento dei geositi nella pianificazione urbanistica, considerato che entro il 2008 tutte le regioni che hanno redatto il piano paesaggistico dovranno procedere ai necessari adeguamenti così come previsto dall'art.156 del dlgs. 42/2004. verso il repertorio nazionale dei geositi l'istituzione di un “repertorio nazionale dei geositi” che selezioni i siti di maggiore interesse geologico, è un passo necessario per le successive azioni di tutela e conservazione nella pianificazione del territorio. il censimento dei geositi è un mezzo, uno strumento per approdare al repertorio nazionale dei geositi. il primo è un raccolta di dati e informazioni, il secondo è un atlante all'interno del quale rientreranno solo i geositi certificati da una commissione creata ad hoc. attualmente il censimento nazionale dei geositi conta circa 3700 segnalazioni, molte regioni ed enti locali hanno posto in essere diverse azioni, ognuna adottando dei propri criteri di valutazione e gerarchizzazione, per la realizzazione di censimenti dei siti di interesse geologico che dovranno confluire all'interno del censimento nazionale gestito dall'apat. l'istituzione di un “repertorio nazionale dei geositi” che selezioni secondo criteri condivisi a livello nazionale, i siti di maggiore interesse geologico, è un passo necessario per le successive azioni di tutela e conservazione nella pianificazione del territorio. per questo, d'intesa con il comitato di coordinamento geologico tra lo stato, le regioni e le province autonome (c.c.s.r.), è stato deciso di costituire un gruppo di lavoro che per la valutazione-validazione dei geositi di interesse nazionale presenti in banca dati apat. le segnalazioni dei geositi, prodotte dai servizi geologici regionali, dalle agenzie per la protezione dell'ambiente delle regioni e delle province autonome, dalle università e dagli enti di ricerca, raccolte e catalogate dalla segreteria tecnica del settore tutela del patrimonio geologico dell'apat, verranno trasmesse al comitato di coordinamento geologico tra lo stato, le 77geositi e gssp le attività del dipartimento ... regioni e le province autonome (c.c.s.r.) per la convalida ed il successivo inserimento nel repertorio nazionale dei geositi. il complesso delle attività si articola nelle seguenti fasi: la distribuzione della scheda di censimento1 disponibile su supporto cartaceo e informatico la ricognizione dei dati sul campo, e compilazione della scheda di censimento da parte dei rilevatori; la verifica delle informazioni contenute nella scheda (georeferenziazione su cartografia, bibliografia...) l'archiviazione e l'organizzazione dei dati in un db nazionale; la gestione e l'aggiornamento dei dati inerenti i geositi e loro restituzione su report e cartografia; la valutazione-validazione dei siti segnalati attraverso il gdl all'interno del ccsr il repertorio nazionale dei geositi i global boundary stratigraphic section and point (gssp) grazie inoltre agli accordi di collaborazione con la commissione italiana di stratigrafia della società geologica, con la società paleontologica e con il museo di storia naturale di firenze si sono intessute le basi per l'inserimento nella banca dati dei global stratotype (gssp) e siti di interesse paleontologico e mineralogico. i global boundary stratigraphic section and point (gssp) sono località mondiali in cui sono registrate il maggior numero di informazioni fisiche, chimiche e paleontologiche su un limite tra due ere geologiche e dove tale limite sia fisicamente presente nella letteratura scientifica italiana i gssp sono definiti da due termini, il primo, stratotipo, indica la successione litologica che caratterizza l'intervallo geologico che contiene il limite tra due ere; il secondo, chiodo d'oro, rappresenta invece il limite fisico tra due ere ed è il piano tra due strati che mette in contatto rocce di un'età con rocce dell'altra età. le località che vengono definite gssp, sono il punto di riferimento mondiale e devono essere prese in considerazione in qualsiasi caso si renda necessario valutare se una determinata roccia appartiene a un determinato intervallo geologico. i gssp, selezionati da una commissione internazionale, la “international union of geology sciences”, devono soddisfare requisiti di accessibilità e fruibilità, ed essere correlabili stratigraficamente con altre località nel mondo. tali gssp non sono eterni e possono essere rimpiazzati in qualsiasi momento da una successione geologica più completa presente in un'altra parte del mondo.lo stato di conservazione pertanto è fondamentale e legato alla valorizzazione e fruibilità del bene. 1la scheda di censimento è scaricabile in formato pdf sul sito apat all'indirizzo: h t t p : / / w w w . a p a t . g o v . i t / s i t e / i t t/progetti/il_censimento_nazionale_dei_geositi/ ad oggi, nella banca dati apat, sono presenti sei dei sette gssp italiani ufficialmente approvati da iugs di cui di seguito si riporta un elenco sintetico: regione piemonte: sezione di lemme carrosio (alessandria) stratotipo del limite oligomiocene età: 23.8 ma approvato da iugs: anno 1996; regione marche: sezione di massignano (ancona) stratotipo del limite eocene-oligocene età: circa 34 ma approvato da iugs: anno 1992; regione marche monte dei corvi (ancona) base tortoniano approvato da iugs: anno 2003; regione calabria sezione la vrica (crotone) limite plio-pleistocene (fra terziario e quaternario) approvato da iugs: anno 1985; regione sicilia sezione di monte san nicola (caltanissetta) stratotipo del limite piacenzianogelasiano (pliocene medio-superiore) età: circa 2.6 ma approvato da iugs: anno 1996; regione sicilia sezione di capo rossello-punta piccola (ag). stratotipo del limite zancleanopiacenziano (pliocene inferiore-pliocene medio) età: circa 3.6 ma approvato da iugs: anno 1997; ed uno di quelli in corso di formalizzazione. regione marche sezione di gorgo a cerbara (pesaro urbino) stratotipo del limite aptiano-albiano in corso di formalizzazione da iugs. 78 fig. 1 le fasi operative del progetto “il censimento nazionale dei geositi”. “the national geosites' census”: the phases. fig.2 carta di prima attenzione dei geositi e gssp segnalati. geosites and gssp cartography l. bonci et al. le azioni di tutela, valorizzazione e fruizione la conservazione e la tutela dei geositi può avvenire soltanto attraverso un documentato ed impegnativo lavoro collegiale di individuazione, catalogazione, valutazione e divulgazione dei risultati. le azioni da intraprendere per la tutela dei geositi che saranno validati e dunque inseriti nel repertorio nazionale, dovranno essere mirate a sensibilizzare gli amministratori degli enti regionali, provinciali e comunali, affinché possano intraprendere le opportune iniziative di tutela e valorizzazione dei siti di interesse geologico. a tal fine il servizio ha programmato una serie di attività quali: la pubblicazione sul sito web apat del repertorio nazionale dei geositi; l'attivazione, presso apat di un tavolo di lavoro con la partecipazione dei rappresentanti dei servizi geologici regionali e dei rispettivi referenti scientifici in cui poter confrontare le criticità e le problematiche relative ai geositi ed alla loro valutazione e gerarchizzazione; per i gssp, la cui rilevanza scientifica è già stata riconosciuta a livello internazionale dalla international union of geological sciences, si condivide la proposta della commissione italiana di stratigrafia per la costituzione di uno specifico gruppo di lavoro coordinato da apat, con la partecipazione dei referenti scientifici per ciascun gssp, avente l'obiettivo di predisporre specifici progetti per la valorizzazione, protezione e fruizione. infine, tra le iniziative intraprese per l'anno internazionale del pianeta terra, apat, insieme ad altre 53 organizzazioni nazionali e internazionali di 43 paesi, partecipa al progetto onegeology il cui obiettivo è quello di rendere pubblici e accessibili via internet i migliori dati di cartografia geologica disponibili a livello mondiale (scala 1:1.000.000), attraverso la conversione delle informazioni in una nuova lingua geologica universale (geosciml). nell'ambito di questo progetto si è deciso di rendere disponibile come strato informativo di interesse geo-turistico, collegabile quindi alle altre informazione geologiche, i dati presenti nel repertorio, rendendoli accessibili a più utenti al fine di favorirne così una più ampia diffusione. bibliografia generale cowie j. w. et alii (1986) guidelines and statutes of the international commission on strtigraphy (ics), cour. forsch. inst. senckenberg, 83, pp. 1-14 d'andrea m. (2000) servizio geologico nazionale: progetto “conservazione del patrimonio geologico italiano”. nota informativa. giornale di geologia, se 3, 62, suppl., pp. 121-124. d'a ndrea m., a ngelelli f. (2001) progetto “conservazione del patrimonio geologico italiano. invito alla paleontologia, paleoitalia, 5, pp. 9-15. d'andrea m., lisi a., mezzetti t. (2005) patrimonio geologico e geodiversità, esperienze ed attività dal servizio geologico d'italia all'apat, apat, rapporti 51/2005, pp. 59-63 remane et alii (1996) revised guidelines for the establishment of global chronostratigraphic standards by the international commission on stratigraphy: episodes, 19, pp. 77-81. siti internet ∗ http://www.apat.gov.it/site/it-it/ ∗ http://www.deaprofessionale.it. ∗ http://www.onegeology.org/ 79 ms. ricevuto il 2 aprile 2008 testo definitivo ricevuto il 17 aprile 2008 ms. received: april 2, 2008 final text received: april 17, 2008 geositi e gssp le attività del dipartimento ... amq106 margaritora et al pc7 jpg.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 33 (1), 2020, 115-132 the lower and middle palaeolithic settlements in the baldo-lessini mountains. results from a gis investigation. davide margaritora1, alessandro dozio1, giorgio chelidonio1, maria chiara turrini1, marco peresani1, 2 1 università di ferrara, dipartimento di studi umanistici, sezione di scienze preistoriche e antropologiche, ferrara, italy. 2 istituto di geologia ambientale e geoingegneria, consiglio nazionale delle ricerche, milano, italy. corresponding author: marco peresani <marco.peresani@unife.it> abstract: on the monti lessini and the monte baldo, two mountain areas of the veneto pre-alps, studies grounded on human ecology, landscape use and site catchment analysis are still sparse or standing at a preliminary state. a factor of bias is the limitation of the archaeological record that was subject to many paleoenvironment processes, compromising its conservation, with substantial loss of information in the open-air sites. in order to shed light on the lower and middle palaeolithic settlements in these sectors we apply gis analysis of location features, as a support provided by the methodological innovation in archaeological research. the analysis is significant for the comprehension of territoriality and also provides tools available for the protection of archaeological and cultural heritage in these areas. site location preferences are the result of a complex decision-making process. using a methodology based on territorial and employment parameters, already successfully applied in other contributions, the results obtained are key issues in the understanding of subsistence strategies, territorial occupation and settlement patterns during the lower and middle palaeolithic. keywords: palaeolithic, settlement, landscape, gis, venetian prealps. � 1. introduction since the end of the 19th century, the monti lessini and the monte baldo, two mountain areas in the central southern pre-alps, are successfully surveyed for investigations on the lower and middle palaeolithic sites, supported by excavations and multidisciplinary projects. especially in the monti lessini, where the number of mousterian sites counts the highest in veneto, a great bulk of data was produced from deposits in caves, rock shelters and in open air sites; remarkable when compared to other mountain ranges in italy. therefore, the study of the settlement system is possible despite the increasing dearth of information as the evidence dates back in time to the oldest record of palaeolithic archaeology. aside the encouraging support provided by the methodological innovation in archaeological research, studies grounded on human ecology, landscape use and site catchment analysis are still sparse or standing at a preliminary state. a factor of bias is the limitation of the archaeological record to mountain or hilly sectors that were lapped only by alpine glaciers and non intensively or only partially affected by periglacial processes, or those fluvial terraces spared by destructive post-depositional processes. as the preservation degree varies, not all the finds share the same informative potentiality. as a consequence, many aspects of the settlement system inferred from site exploitation territory, site function and raw material circulation can only be studied on a limited range of evidence, the more detailed of which are provided by the stratified archives. the layout of these contexts allows exploring human behavior in relation to the environmental context. on the other hand, the open-air sites were strongly affected by post-depositional processes which caused the impoverishment of traces of past human activity with substantial loss of information. anyway, their location features are equally significant for territoriality and site catchment analyses under the focus of the following work. 2. brief presentation of the monti lessini and the monte baldo the monti lessini, also called "lessinia", is a prealpine mountain group located north of the town of verona belonging to the veneto pre-alps. morphologically identified as carbonate plateau, it bounds with val d’adige valley to the west and with valle di leogra valley to the east (fig. 1). the group is limited by the carega massif, which reaches up to 2260 meters of altitude, and by “valle dei ronchi” valley to the north, whereas on the south it gently dips towards the alluvial plain of the adige river and other tributary rivers. the plateau reaches 1860 meters of elevation and slightly bends southwards; it can be considered a monocline structure with a trapezoidal shape, where the shortest side is the northern one. it is radially dissected by several valleys developed along the tectonic lines of the whole area; some sections take the form of a canyon, locally termed vai. the top surface of the plateau could be interpreted as a late tertiary erosional surface, dissected by tectonic activity and eroded in correspondence of the nne fault systems https://doi.org/10.26382/amq.2020.13 116 margaritora d. et al. (zampieri, 2000). generally, the plateau top and the summits of the ridges were mainly affected by weathering, karst and slope processes which led to the development of terra rossa type paleosols (castiglioni et al., 1990). as for monte baldo, it is an alpine group in the sub -section of the gardesane pre-alps, in the section of the bresciane and gardesane pre-alps (marazzi, 2005). it bounds with the garda lake to the west, with the adige valley to the east, with the loppio valley to the north and to the south with garda gulf, caprino depression and the moraine amphitheater of rivoli veronese. it mainly consists in a mountain range, reaching up to 2219 meters, that develops in the north-east/south west direction, and in a series of ridges, small plateaux and terraces in the southern, eastern and northern sides. the group rises asymmetrically: the western side slope varies from 40% to 80% at the top, while the eastern side consists in plateaux and depressions hanging on the steep right slope of the adige valley. geologically, the mountain area is constituted by a stratigraphic succession of carbonate rocks formed in a marine environment, with high presence of chert outcrops (bosellini et al., 1967; carraro et al., 1969). depending on their composition, position and permeability, the various formations exert an influence on the hydrography hydrography the structural and lithological control on the hydrography is strong which is divided into a dense network of main valleys, to which other smaller valleys connect from the ridges (pasa, 1954). these result both by the mechanical erosion and by the chemical erosion caused by water along fault lines and tectonic fractures. both the mountain and hill areas have few superficial water flows, are mainly inactive or only temporarily active -, while they are sculptured by a dense karst hydrographic network. the springs are closely linked to rainfall and the flow rate is not constant over time. most of them are not perennial. the effects of karst processes are not only visible from the hydrographic network, but also from a series of different superficial and underground morphologies, developed because of the numerous faults and fractures that accelerate and facilitate the path of water through the rocks (sauro, 1973; mietto & sauro, 2000). therefore, these morphologies are expression of fluvialand tecto-karstic styles: that is well evident from the superficial forms, from the sinkholes, mostly present along fracture lines or along stratigraphic joints, especially between the maiolica and the underlying jurassic limestone. during the quaternary the area was partly covered by the adige glacier or by the local glaciers attested on the upper part of the monti lessini, the carega massif, the summit of the monte baldo chain (sauro, 1973; sauro & zampieri, 1999). periglacial conditions activated strong erosion of the paleosols, accumulations of slope deposits, especially in the central part of the plateau, loess sedimentation spread all over the relief from the middle pleistocene onward (magaldi & sauro, 1982; castiglioni et al., 1990). deposits in caves and rock shelters along the slopes provide data for estimate that the deepening of gorges and valleys occurred at least from the late middle pleistocene (castiglioni et al., 1990; cremaschi, 1990). anthropogenic erosion during the holocene strongly affected the main slopes especially starting from the neolithic. the lessini valleys are occupied by mainly gravelly, sandy and pelitic floods several meters thick, in addition to the frequent detrital deposits at the foot of the steepest slopes consisting of limestone and dolomitic formations. the lessini and baldo foreland include a large alluvial plain that mostly originated during the middle and late pleistocene from the main river, the adige and its tributaries from the central and eastern monti lessini (de zanche et al., 1977; ferraro, 2009). particularly the western sector, is an area situated where the adige spreads from its long and deeply incised valley which dissects the mountain range up to the alpine watershed. 3. historical context the lessinia region can be undoubtedly considered one of the most prominent areas for the development of prehistoric archaeology in italy (aspes, 1984; 2003; aspes et al., 2002). some first paleontological observations already began in the first half of the 18th century: for example, in 1739 the priest gregorio piccoli described the discovery of faunal bones in a cave locally called “la taneséla” in proximity of alfaedo (piccoli del faggiol, 1739; curi, 2001). consistent with biblical thinking, which permeated most of the researchers of the time, he interpreted those fossilized remains as "diluvial wild beasts" (sauro, 2017). few years later (fortis, 1786), several fossilized bones of elephas meridionalis cromeriensis (and other coeval large mammals, such as rhinos sp.) (bon et al., 1991), where discovered at serbaro di romagnano and, similarly, classified as “antidiluvian”. the first scientific approach to paleontological discoveries in the lessini mountains was published by the museum of natural history of vienna: the naturalist abramo massalongo, observed that carts full of pleistocene vertebrate bones (mainly of ursus spelaeus), extracted from the clayey layers of the karstic cave complex covoli di velo, were brought downstream and sold as fertilizers (massalongo, 1851). associated to lithic artefacts, these findings were brought to the attention of the academy of agriculture, arts and commerce of verona, the royal venetian institute of sciences, literature and arts and the “notiziario degli scavi” by, for the most part, stefano de stefani. however, the rate of discoveries of new pleistocene sites increased mostly in the first half of the 20th century, thanks to the untiring activity of raffaello battaglia, along with an intense scientific production (battaglia,1957; latella & sauro, 2007). his perseverance in publishing the results of his research had positive repercussions in the verona area, as did the reports from giorgio dal piaz and the excavations and recoveries at the quinzano quarries (cave di quinzano) executed from 1933 to the late ‘50s by battaglia himself, paolo graziosi and piero leonardi (see aspes, 1984, for a complete bibliography). during the second world war and especially in its aftermath the researches were consolidated under the coordination of angelo pasa, francesco zorzi and p. leonardi, leading the natural history museum of verona to become a fulcrum for the activities in the fields of pal 117 aeontology and paleoethnology, even beyond the confines of the lessinia region (zorzi & pasa, 1944-45; zorzi, 1959). the above-mentioned quinzano excavations were followed by findings of new artefacts from the surface, excavations in the ponte di veja caves, the discovery of grotta del mondo cave and the interventions at riparo mezzena rock shelter by f. zorzi, a. pasa and maria vittoria durante pasa and those at riparo zampieri by arturo palma di cesnola. the untimely demise of a. pasa in 1966 coincided with a quiescence of the scientific activity in the verona area, compensated by the institute of geology of the ferrara university with the start of decades-long excavations at riparo tagliente rock shelter and of new researches in the ponte di veja caves (broglio et al., 1963; bartolomei & broglio, 1975). this period of intense investigations was fundamental for the studies on the prehistory of the verona area in the following years (leonardi & broglio, 1962). extended surface researches were led also by the centro studi e ricerche (center for studies and researches), headed by giovanni solinas between 1950 and 1965, with numerous reports of sites and sporadic findings in the lessinia localities of ceredo, lughezzano, cà verde and more. the activity of the natural history museum since the ‘70s and its dense network of collaborators (g. chelidonio, f. spadoni, l. farello, a. castagna and others) lead to the detection of one of the highest densities of palaeolithic sites known on the alpine arc, not only on the monti lessini, but also on the monte baldo (pasotti, 1970; chelidonio, 1980; chelidonio & rosà, 2011; chelidonio et al., 2015). the traces distribute through a wide altitude range, between 80 and 1600 meters (battaglia, 1957; zorzi, 1959; leonardi & broglio, 1962; peretto, 1980; chelidonio, 2017; dalmeri & duches, 2008), reaching the valley bottoms and the karst surfaces on the plateau. cavities are much better represented, with grotta di fumane cave, riparo mezzena and riparo tagliente (for a complete bibliography on this last site until the beginning of the ‘80s see bartolomei et al., 1982). open air sites were reported in the higher vajo di squaranto and on the sub-structural terraces at lower altitudes on the ridges between the mezzane and illasi valleys. along with the activities on the field, the superintendence for archaeological heritage of veneto sustained with constancy projects of collaboration with local amateurs and projects for the revision of palaeolithic industries, often finalized to the fruition of this rich archaeologic corpus in the museums of the territory. fig. 1 map of monte baldo and lessini mountains showing the location of palaeolithic sites analyzed. technical notes: coordinate system: monte mario/italy zone 2 (fuso e) datum: roma 40 projection: gauss-boaga fuso: est epsg: 3004; digital elevation model (base topography veneto region dtm 5 m, http://www.regione.veneto.it/web/ambiente-e-territorio/geoportale), garda lake (http:// www.sinanet.isprambiente.it/it/sia-ispra/download-mais/). the lower and middle palaeolithic settlements in the baldo-lessini mountains. results from a gis investigation 4. archaeological context the hefty collection of sites and finds ascribable to the lower and middle palaeolithic or to a generic ancient palaeolithic on the monti lessini and the monte baldo is associated with variable context conditions (fig. 1). the lower palaeolithic finds are numerous but of extremely uncertain chronological positioning, due to the erosion and the deep post-depositional weathering to which these archaeological contexts have been subjected. their attribution was therefore assumed essentially on the tecno-typological characteristics of the lithic artefacts, or by the degree of patination of their surfaces. the oldest lithic assemblages are composed of mostly thick flakes, sometimes retouched and in association with some bifaces. assemblages from the quinzano quarries, monte gazzo and cà palui are more recent, characterized by the association of levallois artefacts and bifaces. the quinzano quarries remain still the most important site, also because of the association with faunal remains of deer, elephant, fallow deer and roe deer (zorzi & pasa 1944-45), and a human occipital. this important pedo-sedimentological sequence was firstly described and interpreted by zorzi & pasa (1944-45) and pasa (1956) and, few decades after, considered by m. cremaschi as a record of potential reference for the geomorphological evolution of the landscape at the foot of the lessini. the lower and middle palaeolithic levels are embedded in the lowermost macro-unit (unit 1, cremaschi, 1984), an alternance of palaeosols and slope waste deposits, separated by erosional surfaces with stone-lines. unit 1 is sealed by the fluvial sediments of unit 2. the richest sources of information are the contexts preserved in the atrial cavities and under rock shelters, along stratigraphic deposits at times complex and articulated. these are key archives with information about chronology, evolution of natural environments and various expressions of human behavior that have manifested during the last glacial cycle. among the deposits systematically explored, we mention riparo zampieri, riparo mezzena, the “cave a” of veja, riparo tagliente, grotta della ghiacciaia and grotta di fumane. currently the data of greater detail come from the excavations in progress at grotta di fumane and riparo tagliente, whose deposits provide useful elements for developing studies on food subsistence, the organization of living spaces, the exploitation of land resources and human mobility in the territorial belt of the lessini and the upper po plain. grotta di fumane, in addition, is a key site for the middle palaeolithic transition with the upper palaeolithic, with the oldest cultural attestations ascribable to the anatomically modern humans. grotta di fumane preserves a 12m thick sedimen 118 tary sequence composed of four macro-units, s, br, a and d covering a chronological range extended from mis 5 to mis 2 (bartolomei et al., 1992; martini et al., 2001) with a cultural record ascribed to the mousterian, uluzzian, aurignacian and gravettian cultures. assessments based on sedimentological, pedological and palaeontological analyses have been previously reported by cassoli & tagliacozzo (1994), cremaschi et al. (2005) and lópez-garcía et al. (2015). current investigations are focusing on the late mousterian levels with their dense scatters of lithic and faunal remains as in units a11, a10, a9 and a6 (peresani, 2012; peresani et al., 2011a; 2011b; 2017). mousterian industries at riparo tagliente are associated with amounts of faunal remains recovered all across the stratigraphy and especially in extensively explored uppermost levels (bartolomei et al., 1982; arzarello & peretto, 2005). grotta della ghiacciaia preserves a short sedimentary series composed of three macro-units that record environmental evolution in the first part of the late pleistocene with evidence of human presence in the two upper macro-units (bertola et al., 1999). riparo zampieri and “grotta a” di veia were settled approximately during the late pleistocene, despite dating programs are still lacking. a different issue concerns riparo mezzena. the mousterian assemblages recovered in this small shelter dates to the late middle palaeolithic (bartolomei et al., 1980), although serious uncertainties affect the consistency of the sedimentary sequence and particularly the chronological position of the presumed neanderthal remains (condemi et al., 2013), now directly dated to the late neolithic (talamo et al., 2016). sites poorer in archaeological data have been identified in open air at various points of the lessini, mainly in the central-western sector, where vitreous flint and chert deposits abound. the same conditions are also found in the last open-air sites discovered on the lessini at the highest altitudes (1400-1600 meters), in the high vajo di squaranto, and on sub-structural surfaces and terraces at lower altitudes along the ridges between the valleys of mezzane and d’illasi. similarly, the monte baldo chain has also returned some of these evidences, represented by levallois lithic industries on the surface, with extremely poor information on chronology, environmental context and significance of human presence. most of the sites located in the basiana valley vary between 1050 and 1068 meters a.s.l., an elevation range which was neither unreached by the erosional activity of the local glaciers nor covered by the lateral moraines of the adige glacier. basiana valley, along with tasso valley, are part of a group of plateaux connected to the monte baldo syncline (chelidonio, 2004). finally, in 2017 the vajo salsone site was discov----------->>>> tab. 1 archaeological sites (multilayered sites as singles cases) and their geographic area (geog), altitude (h a.s.l.), geological substrate (geol), context of find (cont), drainage basin (dr basin), topography position, slope value, slope range (sl range), cultural assessment (cult) and reference. note for geological substrate: eocene limestones (eoc l), oolitic limestones (ool l), maiolica (m), quaternary deposits (qu dep), scaglia rossa (sr), basalt (bas), rosso ammonitico veronese (ra), grigi limestones (grey l) and ialoclastite (ialo); for context of find: surface (surf), depression (dep), karst grike (kg), dolina (do), plowed field (pf), stratigraphic layer (layer); for position: alpine pass (ap), top of the ridge (top), medium slope (med sl), bottom valley (bot); for cultural assessment: mousterian (mou), archaic mousterian (arch mou), acheulean (acheu). margaritora d. et al. 119 the lower and middle palaeolithic settlements in the baldo-lessini mountains. results from a gis investigation ered on the right slope of the middle valpantena. it is represented by huge amount of levallois lithic artefacts and faunal bones contained in a karst pit developed in oolitic limestones and opened during a road cutting (peresani et al., 2018). being the entire archaeological record in secondary deposits and still undated, this makes the location of the original site uncertain. 5. materials and methods the territorial and spatial analysis of human occupation during lower and middle palaeolithic in monte baldo and monti lessini required a geo-localization of sites (caves, rock shelters and open-air sites). their cultural attribution was based on lithic industry: the acheulean was defined by the presence of bifacially flaked handaxes; the archaic mousterian by levallois or discoid technologically-based industries associated to bifaces; the mousterian by levallois and/or discoid industries, despite the presence or absence of retouched tools. 5.1. archaeological data set the analyses were carried out separately for the two distinct geographic areas: identifying 62 sites for the lessini mountains, for a total of 130 frequentations. of these, 73 frequentations, for a total of 55 sites, are open -air sites. in monte baldo area only 18 sites have been identified, none of which is multi-layered (tab. 1). for both areas, analyses were carried out on all sites, all sites count the multi-layered context a single case, all open-air sites and the open-air sites considering the multi-stratified sites a single case. the analyses were carried out separately for the two distinct geographic areas: identifying 62 sites for the lessini mountains, for a total of 130 frequentations. of these, 73 frequentations, for a total of 55 sites, are open -air sites. in monte baldo area only 18 sites have been identified, none of which is multi-layered. based on literature, 11 categories of discovery areas were established: "plowed field" "quarry"; "depressions", a landform sunken or mountain seasonal or permanent pools of unknown origin; "dolina"; "caves", excavated deposits in caves and rock shelters; "layer”, a stratified deposit exposed during construction works; "karst grike"; "surface", collecting during survey; "bottom valley"; "slope". in several cases, evidence was not enough clear to assign findings to any of these categories. 5.2. methodology in order to record the exact position of each site mention by literature two weeks survey were conducted. 38 sites were located using "garmin 60" gps model. when the precise finding area was no longer detectable coordinates were extracted by referring to the nearest 120 place name. in other cases, recent buildings and forest made the sites inaccessible. thus, it was necessary to use the "capture coordinates" function of qgis for recording their position and place them on the regional technical map of the veneto region, 1:10.000 raster format. then a database based on several attributes was developed. some of them were extrapolated by direct observation during the surveys, whereas others were inferred from terrain parameters generated by the original dtm, which was provided by the geoportal of veneto and trentino alto adige regions (1:10.000, cell size 5m series). attributes are listed below: i absolute altitude: the altitude of the site above modern sea level. for the examined area, the difference between modern and pleistocene sea levels is irrelevant, since all the sites are located far inland and are not subjected to pericoastal factors. furthermore, the potential magnitude of the still active tectonic dislocations cannot be overlooked in the interpretation of the absolute altitude. given the alpine uplifting, that could be estimated to be of one meter every 1000 years (sternai et al., 2019), the primary elevation of a 100 ky old site could differ by at least 100 meters from the present-day. however, given the isostatic rebound the alpine chain underwent since the last deglaciation, every attempt to reconstruct the exact dislocation resulting from the combination of tectonic, geomorphic and isostatic processes (mey et al., 2016) remains problematic. ii drainage basin: any area where precipitation collects and drains off into a common outlet. drainage basins converge into other ones at lower elevations in a hierarchical pattern, with smaller sub-drainage basins, which in turn drain into another common outlet. iii topography: the position of every site related to the valley floor. sites positioned at less than 10 m from the valley floor were included in the category "valley floor". sites positioned within 10 m from the top of a mountain ridge are rated to the "summit" category. "pass" has been assigned to sites located near relevant mountain passes. iv slope: the magnitude of steepness or the degree of inclination of a feature relative to the horizontal plane expressed in percentage. v aspect: the cardinal direction to which the cave mouth/rock shelter and open-air site faces. vi geological substrate: the nature of loose sediment or bedrock. vii insolation: the estimation in hours of the sunlightmean time received annually by each site. viii viewshed: the extension of landscape observable from each site, and the dominant direction of visibility, see paragraph 5.2.4. 5.2.1. hypsometry terrain characteristics are important factors for determining settlement location and habitability of an area. hypsometry specifically deals with categories of elevation that comprise catchments, or drainage basins, and related post-depositional factors in archaeological site assemblages. for each analysed area the dem was recalculated margaritora d. et al. based on altitudinal intervals of 100 m (fig. 2). for each interval both the surface <(km²) and its covered percentage in relation to the entire area was calculated. thank to this it was possible to observe whether the sites location related to specific altitudinal ranges are attributable to cultural choices or, more simply, influenced by the area morphology, in which a certain altitudinal range is dominant. 5.2.2. slope the surface topography influences several factors, such as habitability conditions and mobility and accessibility patterns. regarding open air sites it might be also an indicator of the potential of the conservation. in order to calculate the slope, it was necessary to develop a slope model through the dem. a classification into four categories of terrain slopes for the whole area was performed. the categories are divided into ranges between defined percentages (0-10%, 10-20%, 20-35% and 35100%). the slope value for each site was obtained by a query function. 5.2.3. insolation sunlight and sun heating are generally considered as important factors for a favourable habitability condition, especially during severe environmental conditions. in order to calculate the potential amount of sunlight hours received by each site, the insolation map was prepared using bartorelli's tables (1967), which define the annual sunlight hours based of data derived from, latitude, the angle of exposure of the slopes and the percentage of steepness (bartorelli, 1967). the exposure map was reclassified in order to obtain 72 classes (i.e., values from 1 to 72) corresponding to a 5° range each. a reclassification of the slope map was made, obtaining values from 1 to 4, corresponding to the following slope ranges 0-10%, 10-20%, 20-35%, >35%. subsequently, the parameters were recalculated based on a specific formula (slope values multiplied by 100, added to the exposure values) to obtain the values (from 101 to 472) to be reclassified with the rules of the bartorelli tables. 5.2.4. viewshed visibility is other important factor that might influence the choice of stationing sites and/or places to carry out specific activities. we proceeded by setting the observer's height to 1.75 m and an observation radius of 5 km was applied. the operation was carried out for all 75 sites present. for each site the returned area was divided by circular definition, into sixteen equal parts, each corresponding to an interval of 22.5°. in this way, it was possible to establish which cardinal direction corresponds to the portion of territory visible in relation to the observation point. 6. results the examination of the lower and middle palaeolithic sites based on specific parameters reveals some evidence useful to comprehend criteria that mostly influenced the human occupation in the analysed area. 6.1. monti lessini caves and rock shelters are the prevailing archaeological contexts (57 cases) in the monti lessini area (fig. 3a), whereas finds in plowed fields (16) and dolinas (10) are less represented. other discoveries took place on the soil exposed during construction works (7), in sediments within karst fissures (7) and in depressions (7), although the latter were not exhaustingly described in literature. five archaeological sites have been report 121 fig. 2 a, map of monte baldo area hypsometry based on altitudinal intervals of 100 m; b, map of monti lessini area hypsometry based on altitudinal intervals of 100 m. technical notes: coordinate system: monte mario/italy zone 2 (fuso e) datum: roma 40 projection: gauss-boaga fuso: est epsg: 3004; digital elevation model (base topography veneto region dtm 5 m, http:// www.regione.veneto.it/web/ambiente-e-territorio/geoportale), garda lake (http://www.sinanet.isprambiente.it/it/sia-ispra/download-mais/). the lower and middle palaeolithic settlements in the baldo-lessini mountains. results from a gis investigation ed on slopes. few findings occurred during quarrying activities (3), within streambeds of small tributary valleys (2) or on the soil surface (2). in 14 cases it was not possible to trace the context of discovery. considering the multi-stratified sites as single cases (fig. 3b), caves undergo a sharp downsizing (7) and match the number of dolinas. plough zone contexts are still well represented (12), followed by grikes in limestone bedrocks (5), depressions in the ground (5), findings occurred during construction excavations (5), findings along slopes (4), findings in streambeds (2), surface findings (2) and only one in quarry contexts. no context can be assigned for 12 sites. as regard altitude (fig. 4a), most of sites (112) lie under 800 m a.s.l., especially between 300-399 m (43) and 200-299 m (34), whereas finding between 800 and 1000 m are scarce (6). above 1000 m a.s.l., evidence of frequentations is absent, except for those into the ranges of 1400-1499 m (4) and 1300-1399 m (3). findings below 800 m a.s.l. prevail even counting each multi-stratified context as a single item (fig. 4b). sites between 800 and 1000m decrease to four. beyond 1000 m the 122 number of sites is four, all of them located between 1300 and 1500 m. in total, open-air findings confirm the most set below 800 m with a concentration between 200 and 299 m (12), followed by 500-599 m (11) and 300399 m (11) (fig. 4c). above 1000 m a.s.l. frequentation evidences are rare and never exceeding four sites per altitude range. open-air sites considered as a single element (fig. 4d) did not show significant variations compared to all open-air frequentation. according to the one-sample kolmogorov-svirnov test of the data of the single sites (multi-stratified sites counted as single cases) (fig. 5), this distribution seems to follow a normal distribution, and in consequence the concentration of the site between 200 and 700 m is not statistically significant, not even for the whole sample (z =1,089, p 0,200). regarding drainage basin attribution analysis, where the multi-stratified sites are counted as singles cases, many sites do not produce evidence (42). most of the useful sites are associated with second order basins (9), followed by those related to third order basins (8) and first order basins (3). the relationship between each single site (despite multi-occupational ones) and the geological substrate (fig. 6a) reveals eocene limestones as the most occupied (31), followed by oolitic limestones (11) and maiolica (9 sites). rosso ammonitico veronese (3), basalt (3), quaternary deposits (2), scaglia rossa (2), and hyaloclastite (1) are rare. open-air sites (multi-stratified sites counted as single cases) show a similar trend (fig. 6b). analysing sites according to their topography (fig. 7), a preference for medium slope (67) compared to the summit of the reliefs (39) and valley bottom (24) was detected. this range between medium slope and summit reduces (31 vs 27 respectively) considering multioccupation sites as single cases. sites placed at the fig. 3 archaeology discovery context of monti lessini: 3a, all sites; 3b, the multi-layered sites considered as single cases. fig. 4 graph of the altitude range of monti lessini, with interval of 100 m: 4a, all sites; 4b, the multi-layered sites considered as single cases; 4c, concerning all open-air sites; 4d, the multi-layered open-air sites considered as single cases. margaritora d. et al. bottom of the valley fall to three. open-air findings are mostly located at the summit of the reliefs (39), while sites at the medium slope decrease significantly (32). bottom valley sites are only two. multi-stratified open-air sites counted as single cases are both located on the medium slope and at the summit count 27 cases. only one site is positioned on the valley bottom a peculiar case of relation between elevation, geomorphology, sedimentary basin and tectonic uplifting is the mousterian context of cà verde. deposits are contained in a dolina-like depression developed inside a paleo-channel track with partially preserved related sediments of variable thickness, still preserved for over one km in length (brunetto & chelidonio, 1990). the site is located at 100 m of elevation above the adige pleistocene flooding plain. based on this evidence, carton & castaldini (1985) have argued that the cà verde track long pre-dates the adige gorge at ceraino. data relating to the slope exposures (fig. 8a), show that most sites occurred on places exposed to the south west (37), to west (25) and to south east (20). on the other hand, less than half of the previous ones are located near slopes facing north west (6), north east (5) and south (5). the less frequented slopes are those facing east (3), and north (2). numerous frequentations took place in flat areas with null slope exposure values (20). considering multi-stratified sites counted as single (fig. 8b), show that most sites are located on places exposed to the south east (12). on the other hand, less than half of the previous ones are located near slopes facing south west (6), west (6), south (5) and north west (5). the less frequented slopes are those facing east (3), north east (3) and north (2). numerous frequentations took place in flat places with null slope exposure values (26). for open-air sites (fig. 8c), many sites are exposed to the south east (17). the remaining sites are relatively exposed to the north west (6), west (6), north east (5) and south (5). the less frequented slopes are those facing south west (4), north (3) and east (1). the other sites are in flat places with null slope exposure values (26). open-air sites considered as a single element (fig. 8d) did not show significant variations compared to all open-air frequentation. the slope data refer to the total number of sites, with multi-stratified sites counted as single sites. most of them lie on 0-10% (20) and 10-20% (18) incline, in comparison to 20-35% (12) and above 35% (12). regarding the visibility, most sites show very favourable viewpoints to different directions. at a first glance we notice two groups: the most frequent have a wider range of view over the horizon, with several adjacent sectors; in 10 cases, however, the orientation of the visible is less wide, but opened on two distant cardinal directions, sometimes opposite one another. there are 26 sites with visibility oriented in three or more contiguous directions. the most striking result regards ceredo, whose potential viewpoint covers all the cardinal directions. finally, analyses have not been successful in 11 cases. the estimation of the amount of sunlight hours per year (fig. 9) shows that most of the findspots receive over 1500 hours (122 sites; 94%). only 8 cases (6%) 123 fig. 5 one-sample kolmogorov-svirnov test of the altitude data of the single sites (multi-stratified sites counted as single cases). technical notes: number of sites 62; average value 505,306; standard deviation 308,137; skewness 1,625; kurtosis 2,758; d max absolute 0,138; d max+0,138; d max-1,205, k-s z 1,089; p smaller than 0,200. cumulative distribution function (cdf); obs cdf =observed cdf; exp cdf =expected cdf for a lognormal distribution; z =z score. fig. 6 geological substrate (multi-layered sites considered as singles cases) of monti lessini: 6a, all sites; 6b, only open-air sites. fig. 7 topography positions of the sites in monti lessini, in red the quantity and percentage of all sites; in blue the quantity and percentage of only open-air sites. the lower and middle palaeolithic settlements in the baldo-lessini mountains. results from a gis investigation record lower amounts and only one site (1%) stands below 1000 h/yr. most recurrent values are 2547 (32; 25%) and 1725 (26; 20%) h/yr. the value of 1725 h/yr is assigned by default to sites located on a flat area with a maximum inclination of 10%. the highest peak stands at 2613 h/yr. for multi-occupation contexts, considered as single sites, we observed that only six (6%) cases receive less than 1500 hours per year, while only one (2%) less than 1000. 34 (55%) sites fall in the 1000 2000 sunlight h/yr with concentration around 1725 (20). values above 2000 were assigned to 27 (43%) sites. the open-air sites (multi-stratified sites counted as single cases) show the predominance of those with an amount of sunlight hours above 1500 h/y (49; 89%). the sites that fall in the 1000 2000 values are 32 (58%). values above 2000 were assigned to 22 (40%) sites. according to the one-sample kolmogorov-svirnov test of the data of the single sites (multi-stratified sites 124 counted as single cases) (fig. 10), these are not normally distributed, and consequently the concentration of the sites with 1725 (flat areas) of sunlight hours is statistically significant, referred for the whole sample (z =1,681, p 0,010). 6.2. monte baldo in monte baldo there are no multilayered sites, sites in caves or under shelter. among the archaeological contexts (fig. context baldo), findings on the soil surface prevail (5 cases). other discoveries took place in depressions (3), on slopes (2) and within streambeds of small tributary valleys (2). there are few fids in dolina (1), in sediments within karst fissures (1) and on the soil exposed during construction works (1). in 3 cases it was not possible to trace the context of discovery. considering elevation (fig. 11), we note that all cases (18) lie over 600 m. the number of sites varies from 3 to 1 in the various altitudinal ranges between 600 and 1900 m, except for the range 1200-1300 m and 1700 -1800 m which do not present any findings. beyond 1900 m no human presence was found for the chronological period in question. regarding drainage basin attribution analysis, many sites do not produce evidence (16). all useful sites are associated with second order basins (2). the relation between each single site (despite multioccupational ones) and the geological substrate reveals oolitic limestones as the most frequent (7), followed by quaternary deposits (3), eocene limestones (2), maiolica (2), scaglia rossa (2) and gray limestones (2). rosso ammonitico veronese, basalt and hyaloclastite are absent. analysing the site topography, sites locate mostly on the medium side (9) than at the summit of the reliefs margaritora d. et al. fig. 8 slope exposure data in monti lessini refer to the: 8a, all sites; 8b, all findings, the multi-layered sites considered as singles cases; 8c, all open-air sites; 8d, multi-layered open-air sites considered as single cases. fig. 9 values of the annual sunlight hours in monti lessini: in blue dots the values of multi-occupation contexts considered as single cases; in red dots the values of all open-air sites and the multi-layered sites considered as single cases. fig. 10 one-sample kolmogorov-svirnov test of the annual sunlight hours data of the single sites (multi-stratified sites considered as single cases). technical notes: number of sites 62; average value 1948,806; standard deviation 395,417; skewness -0,261; kurtosis -0,335; d max absolute 0,213; d max+0,2013; d max-0,133; k-s z 1,681; p smaller than 0,010. cumulative distribution function (cdf); obs cdf = observed cdf; exp cdf =expected cdf for a lognormal distribution; z =z score. (4), on passes (4) and valley bottom (1). data relating to the slope exposures, show that most sites occurred on places exposed to the north east (3) and east (3). the less frequented slopes are those facing north (2), west (1), south west (1), south east (1) and north west (1). no frequented sites are south facing. numerous frequentations took place in flat places with null slope exposure values (6). regarding the visibility, most sites show very favourable viewpoints to different directions with a wide range of view. in 3 cases, however, the orientation of the visible is less wide, but turned towards two far apart, sometimes opposite, directions. there are 7 sites with visibility oriented in three or more contiguous directions. finally, analyses have not been successful in 1 case. the estimation of the amount of sunlight hours per year shows that all findspots receive over 1200 hours. only 2 sites (1%) stands above 2000 h/yr. most recurrent values are 1725 (6; 33%) h/yr. the value of 1725 h/ yr is assigned by default to sites located on a flat area with a maximum inclination of 10%. the highest peak stands at 2391 h/yr. 7. discussion the gis data produced in this study reveal the existence of a common trend among all the sites, despite the circumstances of their discovery being not uniform. concerning the monti lessini area, although most of the human frequentations were investigated in primary position in stratified cave contexts, a portion of sites is positioned on morphological settings which are subjected to severe erosion; this reduced the optimal conservation of the archaeological record. however, the frequency of these discoveries marks out the importance of karst geomorphic processes for the conservation of the anthropogenic evidence despite its primary or secondary position in territories intensively subjected to erosive action. the development of this geomorphic process is closely related to the geological substrate and to its aptitude to karst morphogenesis, depending on the presence of faults and on the structural layout of the limestone formation. data show that finds are located within dolinas, depressions in the ground and grikes. most of these structures have developed into oolitic limestones where lithic artefacts, loess-like deposits, palaeosols and reworked sediments are preserved, where otherwise would have disappeared. a representative example is the site of contrada barozze, discovered after a road cutting exposed a karst structure filled of loamy-clayey stratified sediments and palaeosols (cremaschi et al., 1990) with lower, middle and late palaeolithic artefacts (chelidonio & solinas, 1983). most of the findings took place on eocene limestone formations, which leaves room for different interpretations and hypotheses. the greater frequency of discoveries recorded on these limestones can be related to a choice of the human groups targeted towards 125 fig. 11 graph of the altitude range of monte baldo, with interval of 100 m concerning all sites. the lower and middle palaeolithic settlements in the baldo-lessini mountains. results from a gis investigation places where this substrate emerges, alongside with other factors driving land use and distribution of resources. one variable that explains the reason that many sites are located on eocenic limestones is certainly the fact that these formations prevail in the foothills area. elevation could be considered as a driving factor, being the 400 m a.s.l. level largely below the lowermost position of the timber line during the late pleistocene. besides, water springs are distributed on eocene limestone bedrocks, sometimes in proximity of volcanic rocks. however, the intensive agricultural exploitation of the soils that developed on these bedrocks favours the surface findings, since ploughing enhances their visibility. it is therefore conceivable that the greater occurrence of findings on arable contexts and on substrates of eocene limestone in comparison to others is the result of bias rather than of a precise choice of settlement. with respect to the valley floor, the greater number of sites is located at medium elevation along the slope and on the top of the ridges. considering individual spots in valley bottom, their frequency increases, even though as a mere consequence of the multilayering at tagliente, mezzena and ghiacciaia rock shelters. given the sedimentary nature of the valley bottoms, it can be assumed that many frequentations located in valley floor areas, at the lowermost elevation, are now covered by thick alluvial sedimentary sheets and are thus no longer explorable. this is confirmed by the exposition of archaeological layers at quinzano and cà verde after intensive quarrying, and by geological data achieved from pits in the middle and lower valpantena at grezzana and san felice extra. no chronological data are currently available on these sedimentary sheets. in the lowermost clayey layer (from -148 to -129 m) of the “verona est” pit, positioned at 52 m a.s.l., pollen association reveals ecological conditions compatible with mis 5e or 5c (sorbini,1993). in contrast, the high occurrence of places at summits might reveal systematic settling of the landscape along possible routinely paths covered by the huntergatherers for reaching the highest elevations and ecotones. it must be considered, however, that locations on top ridges and medium slopes are more visible as a result of exposure caused by erosive processes, favouring survey and surface discoveries. the distribution of sites in relation to the drainage basin does not reveal specific occupational preference for one area but can be considered as a result biased by differences in survey intensity. our data do not output possible correlations or specific recurring trends for the proximity to a precise hydrographic order, although we cannot neglect that this was an important parameter for settling down in the landscape. relation between slope intervals and finding contexts does not reveal any trends, if we except surface collecting on ploughed fields, depressions and soils, which are the most frequent in the two lowermost intervals (0-10% and 10-20%). we note the recurrence of caves in the > 35% range referring slope where they are located. data relates to rough and steep slopes covered for reaching those favourable, stable positions. the distribution of single spots and multi-layered sites 126 (fumane and tagliente) on slopes reveals a prevalence of sw and w expositions, despite most of the findings are located on flat areas with undeterminable orientation. the lowermost value has been recorded for slopes oriented to the n and, slightly higher, to the s. it can be assumed that the great frequency of sites exposed from ne to se and sw-nw reflects the morphological characteristics of the ridges, aligned to directions converging to the north. therefore, this result should be interpreted as an expression of the hilly landscape morphologies, rather than an evidence of locational preferences. to reinforce this hypothesis, we explored the correlation between slope and solar exposure for all frequencies. although sites facing south get the highest exposure values, most of the frequentations occur between 50° n and 150° n, and between 200° n and 310° n, with lower insolation values in some cases with discrepancies of over 1500 hours. the numerosity of sites exposed to the se (112.5° n 157.5° n) is remarkable: absolute values are high, between 2194 and 2428 sunlight h/y and play in favour of occupational choices driven by both the landform and profitable solar exposure. therefore, insolation can be considered an important parameter in the settling of an area. the computation of the yearly amount of sunlight hours for each single site reveals a major occurrence between 1300 and 2200 hours, with peaks at 1742 and 2451 and that these frequencies correlate to the peculiar characteristic of the landscape. as before, places with insolation over 1500 hours were probably targeted for the implantation of the seasonal camps. moreover, several sites with values >2200 h/y testify the settling of specific areas with favourable characteristics in sun exposure, despite their poor representation among the totality of the investigated area. from the data above, the occupational preference for some areas over others could be conceivable. in all cases, the most represented altitudinal range are 200299 m and 300-399 m a.s.l., however it has be noted that the southern offshoots of the ridges were more surveyed than other morphological traits of the landscape (fig. 12). being placed at medium-low altitudes, ridges fig. 12 graph of percentage curves: in red the percentage of surface of altitude ranges, in relation to the entire area; in black the percentage of the sites located in each altitude range. the columns show the number of the sites contained in the altitude ranges. margaritora d. et al. might have led to over-representing some data. figure 13 shows the correlation between the altitude of sites (multi-layered sites taken as single cases) and the annual sunlight hours and does not in favour of hypothesizing the existence of a specific strategy of settlement and territorial occupation. criteria of settlement does not seem were influenced by the conditions of sun exposure, showing a wide variability at all altitudinal range. we infer that the exploitation of the landscape at high and low altitude does not was driven by significant differences in the sun light parameters for select a specific area. we have seen how low and high altitude sites do not differ in parameters related to sun exposure, likewise the visibility does not significantly vary in function of the elevation. the data show that most of the sites have views that cover several contiguous slices of land towards some of the cardinal directions, while in 10 cases visibility is limited to two distinct directions. when we plotted the sites with a single large visual covering several contiguous cardinal directions, and the respective elevations, we noticed that the variability of width of the visual field does not follow a specific criterion as the elevation increases (fig. 14). the sites below 1000 m range in the number of visibility slices from one to eight cardinal directions, with a variability that does not indicate a specific occupational strategy. for the two sites over 1000 m does not exceed two slices, it emerges that at higher elevations the occupational choice did not consider such parameter as a priority. both of spots set over 1000 meters falls within depressions with severe limitation in the visible slices of territory due to the geomorphological context. besides, a secondary position of the artefacts due to colluviation is conceivable in these sedimentary basins and, therefore, with bias in the divergence between the spots located at low and high altitudes. sites located in valley, like còal del bota in vaggimal and riparo tagliente, have both visible field and directionality oriented in concordance with the valley axis and morphological layout. even for these cases, the visibility parameter does not seem to have been considered in the occupational choice. 8. conclusions the survey and geolocation of the lower and middle palaeolithic sites and findspots on the monti lessini and monte baldo leads to the creation of an applicable database available for studies on settlement dynamics, for archaeological heritage archiving and for the developing of predictive thematic maps, archaeological risk evaluation and archaeological protection. this type of cartography would fill a gap between the tools available for the protection of archaeological and cultural heritage in such an important area for prehistory. using a methodology based on territorial and employment parameters, already successfully applied in various contributions (miller & barton, 2008; garcia, 2012; 2013; garcia et al., 2013), our results and considerations fulfil the proposed objectives. from our output data we notice how in several 127 the lower and middle palaeolithic settlements in the baldo-lessini mountains. results from a gis investigation fig. 13 kendal tau test for the correlation between the altitude of sites (multi-layered sites as single cases) and the annual sunlight hours. wessa, (2017), kendall tau rank correlation (v1.0.13) in free statistics software (v1.2.1), office for research development and education, url https:// www.wessa.net/rwasp_kendall.wasp/. fig. 14 kendal tau test for the correlation between the number of continuative visible directions of sites (multi-layered sites considered as singles cases) to their respective elevations. the graph does not include the sites located by place name and the sites that have returned two opposite portions of visible territory, to maintain compliance of the analysed data. wessa, (2017), kendall tau rank correlation (v1.0.13) in free statistics software (v1.2.1), office for research development and education, url https://www.wessa.net/rwasp_kendall.wasp/. cases the parameters here analysed have been considered in the settlement choice, at least in a certain part of the territory. in many others, however, it seems clear that some recurring values may not be the reflection of the precise search for an area that meets specific requirements. rather, they would be related to the morphological characteristics of that specific part of landscape. in addition, it has been noted that the greater representation of some values does not depend on a choice that takes into consideration well-defined employment parameters, rather it may reflect a research deficit which affected some areas more than others. the attributes related to the context of discovery show that, although most of the frequentations have been found in cave excavations, a great divergence arises from site to site. data inhomogeneity and difference in the location degree of the findings therefore affected the analysis, causing limitations in internal comparisons of our record. attributes inherent to the geological substrates are emblematic of this limit. the great representation of plough contexts on eocene limestone substrates should not be interpreted like an evidence of a precise occupational choice, rather than of a research bias in favour of the ploughed fields, which were ubiquitously present only till the ‘70s of 20th century, often on the southern offshoots of the lessini ridges. the same holds for positions on the top of the reliefs and on medium slope, where surveys were easier on ridges than in forested bottom valleys. being ridges subjected to erosion, possibilities of making surface-type recoveries are enhanced compared to the valley floors, which are urbanized and covered by thick slope waste deposits and alluvial sediments. nevertheless, in few but very meaningful sites such as cà palui, monte gazzo and passo di san valentino, lower and middle palaeolithic artefacts were found in concentrations very likely attributable to knapping activities in proximity of extended outcrops of chert. in the valley floors, the only discoveries occurred following cave research and building excavations, that allowed examining soils and sediments in depth. the same deficit could affect the possibility of proposing recurring trends in the relation of the sites to the river basins, being most of the finding points placed at the top of the reliefs and straddling multiple orders. taking into consideration the data relating to the slope, we can see that the greatest representation of discoveries in the 0-10% and 10-20% ranges is well attested, frequently in ploughed fields, dolinas and depressions in the ground. on the other hand, the presence of five caves on >35% slopes attest the effort of encompassing steeped slopes for reaching stable and favourable niches. the distribution of data on slope exposures does not reveal any occupational preference in relation to a specific cardinal direction, rather it reflects landscape features of the lessini area, with its ridges and slopes exposed from ne to se and sw to nw. the major representation of the sites exposed to se with insolation values between 2194 and 2428 hours per year leaves however the possibility that the choice of the settlements might also be driven by favourable conditions of annual hours of sunshine. our data, for ranges between 128 1300 and 2200 h/y, seem to indicate that camps were positioned basically in function of the landforms. on the contrary, the location criteria for settlements exposed to over 2200 h/y are mostly driven by the preference for areas with matching characteristics of sun exposure. when we plotted sun exposure data with elevation, we did not notice a correlation between the altitude and the search of high number of sunshine hours. from these data it is therefore possible to assume that this parameter did not play a major role in settling within this hilly and mountain landscape, at least in relation to the altitude of the site. the potential visibility related to each site indicates two general ranges. the most frequent are sites with multiple and continuous viewpoints, despite for only one slice of territory. in 13 cases, however, the orientation of the visible is less wide, but faces two markedly different directions, sometimes opposed one another. if we correlate sites with multiple continuous viewpoints to their elevation values, we do not reveal any divergence in land use between sites at low and high elevation. in conclusion, we argue that parameters like geological substrate, position in respect to valley floor and attribution to an order of the river basin are affected by the degree of intensity of research. this was so high in certain areas to generate overrepresentation of the most recurrent values. the great frequency of findings on flat zones does not seem to be affected by this deficit. slope exposure compared to solar exposure allows us arguing a direct dependence of frequentations from the landforms. however, the sites facing se and sites with sunlight values higher than 2200 h/y confirm that sun exposure should be excluded as main criteria adopted to settle that section of landscape. although sparse and fragmentary, current data on the lower and middle palaeolithic settlement system in the hilly and mountain landscape of verona reveal some aspects relatable with the paleogeographic, paleo -economic and cultural contexts of the sites. these could be an expression of the seasonal nomadism practiced by the pre-neanderthal and neanderthal groups based on the settlements in the valley bottom, the upper adige alluvial plain and the mountain range. traces from ephemeral to consistent are scattered at 13001400 m a.s.l., peaking at 1600 m. caves presumably had a main role thanks to their strategic position, being favourable for catchment in different ecological environments through short-range movements. the variety of hunted animal species confirms the possibility to diversify the exploitation of resources of animal origin. if we add the possibility human groups had to easily access the primary exposures and secondary deposits of chert, we can argue that the presence of lower and middle palaeolithic hominins in this mountain range was driven by a set of factors (bagolini & broglio, 1985). whether mountain sites were the edge of a large settlement system extended to the po alluvial plain or were organized in a subsystem articulated in residential sites and specialized camps, it is however still far from being assessed. margaritora d. et al. acknowledgments the authors are grateful to dr. pietro sternai (department of earth and environmental sciences university of milano-bicocca) for suggestions on neotectonic upliftings, to tobia fognani and lucia bartolozzi for revision of the english text and to francesco carrer and ugo sauro who 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(it issn 0394-3356, 2009) al fine di migliorare le conoscenze geologico-stratigrafiche dell’area costiera metapontina, è stato svolto un rilevamento geologico di dettaglio nella zona compresa fra marina di ginosa (provincia di taranto) ed il torrente cavone (provincia di matera). il rilevamento è stato corredato da osservazioni dei caratteri di facies effettuate sia lungo sezioni stratigrafiche esposte che su sondaggi ottenuti tramite cinque perforazioni a carotaggio continuo che hanno attraversato depositi dell’olocene e del pleistocene medio superiore fino ad una profondità di circa 120 m. i depositi affioranti sono stati distinti in due principali unità: ”depositi sabbioso-conglomeratici dei prismi costieri regressivi” (pleistocene superiore) e “depositi della piana di metaponto” (olocene). i primi depositi, sabbioso-conglomeratici, sono stati suddivisi in tre unità litostratigrafiche; le prime due, spesse al massimo 15 m, e rappresentate da prismi formatisi in seguito ad interazioni fra oscillazioni del livello del mare e sollevamento regionale, sono riferibili alle “sabbie e conglomerati di policoro” e alle “sabbie e conglomerati di masseria ricotta” che, in base all’osservazione dei caratteri di facies, sono state attribuite ad ambienti variabili dal marino poco profondo al continentale. la terza unità, in discordanza sulle precedenti, è formata da un “prodotto eluviale” discontinuo e di esiguo spessore. i “depositi della piana di metaponto”, tutti di età olocenica e spessi in genere pochi metri, sono stati invece suddivisi in “depositi continentali” e “depositi di transizione”. i primi sono rappresentati da depositi da fini a grossolani, di origine eluvio-colluviale, fluviale, lacustre e palustre; i secondi invece, sono rappresentati da depositi sabbiosi e/o siltoso-argillosi di spiaggia-duna (attuali ed abbandonati) e deltizi (attuali ed abbandonati). i depositi sepolti sono stati distinti in tre unità grazie all’individuazione di due nette superfici di discontinuità. l’unità più bassa (denominata “substrato”), attraversata per uno spessore massimo di 76 m e riscontrata a partire da profondità variabili da 13 m a 44 m spostandosi da terra verso mare, è costituita da depositi argilloso-siltosi, con intercalazioni di strati sabbiosi, che verso l’alto passano a depositi sabbiosi e sabbioso-ghiaiosi. tali depositi mostrano caratteri di facies riferibili ad ambienti variabili dalla piattaforma all’avanspiaggia. l’età di questi depositi è pleistocene medio superiore. in contatto erosivo sul substrato si rinviene un’unità definita “depositi della piana sepolta di metaponto”, con geometria cuneiforme, e con spessori perforati variabili da 0 a 7 m spostandosi da terra verso mare. tale unità è formata da depositi sabbioso-ghiaiosi mostranti caratteri di facies variabili dal continentale al marino poco profondo. l’età è riferibile al pleistocene superiore. in erosione su tali depositi, o direttamente sul substrato, si rinviene infine un’unità sabbiosa e sabbioso-ghiaiosa, corrispondente ai “depositi della piana di metaponto”, con geometria cuneiforme, e con spessori che aumentano da terra verso mare, fino ad un massimo misurato di circa 48 m. l’analisi di facies ha permesso di riferire tali depositi alla progradazione di un sistema di spiaggia, a luoghi associato lateralmente ad un sistema deltizio, passante distalmente ad un sistema di piattaforma. grazie ad una datazione radiometrica effettuata su un guscio di lamellibranco rinvenuto in un sondaggio alla profondità di 35 m, è possibile riferire tali depositi all’olocene. l’insieme dei dati raccolti ha permesso di realizzare una carta geologica in scala 1:25.000 nella quale sono state cartografate numerose unità litostratigrafiche che formano un quadro nuovo e maggiormente dettagliato rispetto a quello vigente nella letteratura ufficiale. le sezioni geologiche a corredo, integrate anche con i dati dei sondaggi, consentono di ricostruire la geometria dei depositi sepolti, e di delineare la storia evolutiva del prisma olocenico nel tratto di costa considerato. abstract: pescatore t. et al., stratigraphy of the pleistocene-holocene deposits of the coastal metaponto area between marina di ginosa and cavone river (southern italy): geological map, 1:25.000 scale. (it issn 0394-3356, 2009) in order to improve the geological and stratigraphic knowledge of the metaponto coastal area a detailed geological survey has been performed between marina di ginosa (taranto) and cavone river (matera). furthermore, a facies analysis either along stratigraphic sections or on cores obtained from five continuously-cored boreholes, drilling in the holocene and middle – upper pleistocene deposits up to 120 m of depth, has been carried out. the outcropping deposits have been distinguished in: upper pleistocene “sandy-conglomeratic deposits of the regressive coastal prisms” and holocene “metaponto plain deposits”. the first deposits are subdivided into three lithostratigraphic units. the first two units have a thickness variable up to 15 m, and are represented by sandy-conglomeratic prisms resulting from the interplay between sea-level fluctuations and regional uplift; they are referred to “sabbie e conglomerati di policoro” and “sabbie e conglomerati di masseria ricotta”, showing facies features of shoreface passing upward to continental environments. the third unit, up to 2 m thick, is an “eluvial product”, made up of reddish sands with gravelly layers unconformably and discontinuously overlaying the previous deposits. the holocene “metaponto plain deposits” have been distinguished in: “continental deposits” and “transitional deposits”. continental deposits are represented by mainly some meters thick fineto coarse-grained sediments of eluvial, fluvial, lacustrine and palustrine environments. transitional deposits are represented by some meters thick sandy and silty holocene beach-dune systems (modern and ancient) and sandy and clayey-silty deltaic systems (modern and ancient). the buried deposits of the metaponto coastal area have been distinguished in three units thanks to the facies analysis and mainly to il quaternario italian journal of quaternary sciences 22(2), 2009 307-324 308 t. pescatore et al. 1. premessa nell’ambito del progetto di ricerca prin-miur dal titolo: “storia geologica delle piane costiere di metaponto e di sibari durante il pleistocene superioreolocene. fattori climatici ed eventi catastrofici” di cui è stato coordinatore scientifico nazionale il prof. tullio pescatore, le unità di ricerca delle università di bari e di benevento hanno realizzato una carta geologica in scala 1:25.000 della parte di fascia costiera ionica metapontina ubicata tra l’abitato di marina di ginosa (provincia di taranto) ed il torrente cavone (provincia di matera). l’area rilevata ha un’estensione totale di circa 125 kmq, una lunghezza di circa 21 km (parallelamente alla linea di costa), ed un’ampiezza di 6 km. si tratta di un’area morfologicamente piatta, dove le quote variano dal livello del mare (linea di costa) fino ad un massimo di circa 35 m. i depositi affioranti, di età pleistocene superiore-olocene, sono essenzialmente rappresentati da depositi fini e solo in minore quantità da depositi sabbioso-conglomeratici. l’interesse per quest’area risiede in più di un motivo: presenta una notevole importanza archeologica, in quanto sede di insediamenti della magna grecia; è stata oggetto di complesse opere di bonifica, che hanno determinato la sua trasformazione in un’area a vocazione agricola con colture di grande pregio; è oggetto di ampi interventi di pianificazione e trasformazione territoriale legati ad una significativa espansione dell’offerta turistica con costruzione di villaggi a ridosso dell’area costiera, oltre a porticcioli in corrispondenza delle principali foci fluviali. a tale proposito, qualsiasi intervento venga progettato non dovrebbe prescindere da una dettagliata conoscenza geologica dei depositi affioranti e di quelli dell’immediato sottosuolo, in quanto un’area costiera, come quella metapontina, risulta estremamente sensibile a fenomeni quali eustatismo e/o subsidenza, variazioni climatiche, processi marini estremi (mareggiate e tsunami) ed alluvioni, le cui registrazioni nella serie sedimentaria possono suggerire la naturale tendenza evolutiva del territorio e la potenziale attività di processi geologici non sempre riconoscibili solo da dati storici. al fine quindi di fornire una corretta informazione di base, utile anche a scopi applicativi, e di dettagliare il quadro stratigrafico dei depositi della piana di metaponto, è stato realizzato un rilevamento geologico utilizzando sia basi topografiche alla scala 1:2.000 del consorzio della bonifica di metaponto (ente attualmente compreso nel consorzio di bonifica di bradano e metaponto) che ortofotocarte alla scala 1:10.000 della regione basilicata, riportando poi i dati su materiale cartografico dell’igm alla scala 1:25.000, così come qui presentato. come detto, essendo tale area intensamente antropizzata, l’individuazione di alcune morfologie costiere è stata possibile anche grazie all’ausilio sia di una carta geomorfologica prodotta dalla regione basilicata (boenzi et al., 2002), sia dell’analisi di strisciate di foto aeree alla scala 1:33.000 di differenti annate, dal 1954 al 1998; a tal proposito, fra l’altro, è stato possibile individuare antiche morfologie di alvei abbandonati e i più marcati fenomeni di arretramento costiero localizzati in corrispondenza delle foci dei fiumi cavone, basento e bradano, elementi di analisi che trovano accordo con alcuni dati di letteratura (e.g. cocco et al., 1975; capretto, 2003; spilotro, 2004). l’insieme delle informazioni raccolte ha permesso di realizzare una carta geologica dell’area costiera di metaponto nella quale sono rappresentati anche gli elementi morfologici che insieme a quelli deposizionali documentano la dinamica costiera recente ed attuale. inoltre, al fine di meglio caratterizzare i depositi sepolti della porzione di piana costiera metapontina studiata, e che rappresentano anche i terreni di fondazione di numerose opere, nell’ambito dello stesso progetto sono stati realizzati cinque sondaggi di cui qui si presentano i dati litostratigrafici. lungo uno di questi sondaggi è stata effettuata anche una datazione con il metodo radiometrico 14c al fine di definire l’età dei depositi studiati. l’integrazione dei dati di superficie con quelli di profondità ha permesso di fornire un quadro stratigrafico nuovo e dettagliato dell’area metapontina, di definire i caratteri deposizionali ed evolutivi delle principali unità stratigrafiche individuate, e di contribuire alla conoscenza delle ultime fasi evolutive del bacino della fossa the recognition of two important erosional surfaces. the lower unit (called substratum), found beginning from a depth variable from 13 m to 44 m moving seaward, is at least 76 m thick and made up of clayey-silty deposits, with interbedded sandy beds passing landward and upward to sandy and/or sandy-gravelly deposits. the lower boundary was not found, whilst the upper boundary is represented by an erosional surface (se) highlighted by a lag deposit. the facies features of these deposits can be referred to offshore passing upward to shallow marine environments. the age is middle late pleistocene. the intermediate unit is bounded both on bottom and on top by erosional surfaces (se and st). this intermediate upper pleistocene wedge-shaped unit, called “metaponto buried plain deposits”, pinches out landward, passing from about 7 m to 0 m in thickness. it is made up of sandy-gravelly deposits of continental to shallow marine environments. the third upper unit erosionally overlies both the previous unit and the substratum by the st surface. this unit is made up of sands and gravelly sands, and its thickness varies from 13 m to 48 moving seaward, and has been attributed to the progradation of a beach system, laterally linked to a deltaic system, and passing seaward to an offshore system. a lamellibranch shell yielded a not calibrated 14c age of 7.572±50 yr bp for these deposits. the overall collected data allow us to draw a geological map on 1: 25.000 scale that provides a new stratigraphic framework of the outcropping metaponto plain deposits. furthermore, the geological sections obtained also utilizing the boreholes allow us both to reconstruct the geometry of the buried deposits and to outline the evolutionary history of the holocene transgressive prism along the coastal study area. parole chiave: piana di metaponto, pleistocene superiore-olocene, caratteri stratigrafici, italia meridionale. keywords: metaponto plain, late pleistocene-holocene, stratigraphic features, southern italy. bradanica durante l’intervallo temporale pleistocene superiore-olocene in buon accordo con cilumbriello et al. (in stampa) e sabato et al. (in prep.). si fa presente che simili studi sono già stati condotti da alcuni autori di questa nota per l’analisi di altre piane costiere (barra et al. 1999; pe s c a t o r e et al., 2001; pe s c a t o r e & senatore, 2003). 2. inquadramento geologico l’area in oggetto è ubicata nella piana metapontina, prospiciente il golfo di taranto, ed è compresa tra la foce del torrente cavone (in provincia di matera) e l’insediamento di marina di ginosa (in provincia di taranto) (fig. 1). tale area ricade in parte nel f° 201 “matera” (boenzi et al., 1971), ed in parte nel f° 212 “montalbano ionico” (mostardini & pieri, 1967) della carta geologica d’italia alla scala 1:100.000. da un punto di vista geologico-strutturale l’area suddetta corrisponde all’estrema propaggine meridionale della fossa bradanica (e.g. migliorini, 1937), dove affiorano i cosiddetti depositi marini terrazzati (sensu vezzani, 1967) localmente di età pleistocene superiore, e depositi sabbiosi, sabbioso-ghiaiosi e sabbioso-limosi della piana costiera ionica di età olocenica. depositi attribuibili al pleistocene superiore-olocene sono stati individuati anche nella zona marina prospiciente l’area in studio (diplomatico et al., 1985; senatore, 1987; senatore et al., 1988). i primi approfondimenti sui caratteri stratigrafici 309stratigrafia dei depositi pleistocenico-olocenici dell’area costiera ... dei depositi marini terrazzati risalgono alla seconda metà degli anni ‘60 (cotecchia & magri, 1967; vezzani, 1967). in particolare, vezzani (1967) individua 7 ordini di terrazzo, che abbracciano un intervallo di tempo compreso fra il siciliano e il tirreniano; il deposito marino terrazzato del 1° ordine che è il più alto ed il più antico, si ritrova ad una quota di circa 390 m, quello del 7° ordine è il più recente e si rinviene ad una quota di 1015 m s.l.m. successivamente, per gli stessi depositi, altri autori individuano un numero di superfici e di ordini di terrazzi differente, da un minimo di 7 ad un massimo di 11 (neboit, 1975; boenzi et al, 1976; brückner, 1980a, 1980b; amato, 2000). in particolare brückner (1980a; 1980b; 1982) compie uno studio morfologico di dettaglio ed individua nell’area metapontina 11 ordini di depositi identificati con la sigla da t1 a t11 a partire da quello più basso; inoltre brückner (opp. cit.) effettua le prime datazioni dei depositi marini terrazzati, riconoscendo il limite paleomagnetico brunhes/matuyama tra i terrazzi t11 e t10, datando a 500-600 ka bp un livello vulcanoclastico nella parte alta del terrazzo t8, ed infine attribuendo un’età di 63 ka bp (± 3 ka) al terrazzo marino più basso (t1) attraverso il metodo th230/234u. fatta eccezione per bentivenga et al. (2004), che considerano i depositi marini terrazzati come formatisi per fagliamento di un unico ampio originale deposito costiero del pleistocene medio, la maggior parte degli autori interpreta i depositi marini terrazzati, indipendentemente dal loro numero, come la conseguenza del sollevamento dell’area del bacino di avanfossa a partire dal pleistocene medio. tale sollevamento avrebbe profig. 1a) carta strutturale schematica d’italia; b) carta geologica schematica della fossa bradanica; c) carta geologica schematica dei depositi marini terrazzati e della piana costiera metapontina affioranti nella porzione meridionale della fossa bradanica (da cilumbriello et al., 2008, leggermente modificata); d) carta schematica dell’area studiata con ubicazione dei sondaggi e delle sezioni geologiche effettuate. a) schematic structural map of italy; b) schematic geological map of the bradanic trough; c) schematic geological map of the terraced marine deposits and the metaponto coastal plain deposits cropping out in the southern area of bradanic trough (from cilumbriello et al., 2008, slightly modified); d) schematic map of the study area with location of the core-drillings and the geological sections. 310 vocato l’esposizione ed erosione della parte alta della serie di riempimento della fossa bradanica e la formazione, in seguito alle variazioni cicliche quaternarie del livello del mare, di una serie di terrazzi marini in discordanza sulla successione della fossa bradanica affiorante (argille subappennine) (selli, 1962, vezzani, 1967; boenzi et al., 1971; parea, 1986). più recentemente c i l u m b r i e l l o (2008) e cilumbriello et al. (2008) tramite studi stratigraficosedimentologici dettagliati su depositi affioranti in parte nell’area in oggetto hanno evidenziato come ogni deposito marino terrazzato riconosciuto dagli autori precedenti non sia semplicemente relativo ad un unico ciclo trasgressivo-regressivo, come inteso classicamente, ma presenti una ciclicità interna di più alta frequenza. nel complesso quindi, l’intera successione riferita ad un deposito terrazzato non sarebbe geneticamente correlabile alla superficie terrazzata che la delimita superiormente (cilumbriello, 2008). per tali motivi, nei lavori svolti per la realizzazione della nuova carta geologica d’italia alla scala 1:50.000 i depositi marini terrazzati sono stati denominati genericamente come prismi costieri regressivi (sabato et al., in prep). va infine ricordato che studi di carattere stratigrafico regionale (pieri et al., 1994; 1996; tropeano et al., 2002a; 2002b) suggeriscono di non operare più distinzioni fra i depositi di colmamento della fossa bradanica ed i depositi marini terrazzati, e li attribuiscono nel loro insieme ad un’unica unità definita informalmente “depositi costieri regressivi della fossa bradanica” (fig. 1b, c). in questa ottica, i depositi marini terrazzati rappresenterebbero i termini più recenti di riempimento della fossa bradanica. per quanto riguarda l’area di studio, i depositi marini terrazzati affioranti corrispondono a parte del deposito marino terrazzato di 7° ordine sensu vezzani (1967), o a parte del deposito marino terrazzato di i ordine sensu brückner (1980a; 1980b). nell’ambito della realizzazione del foglio geologico n° 508 “policoro” alla scala 1:50.000 sabato et al. (in prep.) attribuiscono gli stessi depositi in parte all’unità delle “sabbie e conglomerati di policoro” ed in parte all’unità delle “sabbie e conglomerati di masseria ricotta”. per quanto riguarda invece i depositi della piana costiera, una loro prima descrizione si deve a vezzani (1967), oltre che a mostardini & pieri (1967) e a boenzi et al. (1971), ed in tempi più recenti a capretto (2003). vezzani (op. cit.), nell’area compresa tra i depositi marini terrazzati più recenti e i cordoni dunari più interni, descrive una successione sedimentaria di sabbie, sabbie argillose e ghiaie, con spessore variabile da 20 m a 40 m, depositatasi sulle “argille marnose azzurre” del calabriano (argille subappennine sensu valduga, 1973) in seguito all’alternanza di condizioni continentali e marine. l’età di questa successione viene riferita al post-tirreniano da vezzani (op. cit.), che inoltre descrive le dune costiere e le spiagge attuali che occupano la fascia litorale. secondo tale autore le dune costiere sono costituite da sabbia fine di colore variabile dal grigio al giallastro e formano una fascia di cordoni paralleli all’attuale linea di costa con ampiezza che aumenta da s verso n fino ad un massimo di 2 km a n di marina di ginosa, dove le dune raggiungono altezze fino a 13 m. l’autore descrive infine una spiaggia sabbiosa attuale di ampiezza variabile da 10 m a 200 m in cui riconosce gli ambienti di avanspiaggia, cordone di spiaggia e retrospiaggia sensu shepard (1948). i caratteri delle dune costiere e delle spiagge attuali sono stati descritti in dettaglio da cocco et al. (1975); questi autori nel tratto di costa compreso tra il torrente cavone e l’abitato di marina di ginosa descrivono un’unità fisiografica rappresentata da spiagge sabbiose delimitate verso terra da una fascia ampia fino a 2 km costituita da cordoni dunari (alti fino ad oltre 10 m) ed aree acquitrinose. le spiagge, rappresentate da sabbie a grana medio fine e a composizione quarzosa, si sviluppano con ampiezza variabile da 20 m a 70 m e sono caratterizzate da una pendenza che per la spiaggia emersa è dell’ordine dei 6° e per la battigia è di circa 9°. localmente vengono segnalati anche tratti in forte arretramento delimitati verso terra da scarpate incise nelle dune con altezza di oltre 3 m. gli elementi morfologici del tratto di piana costiera ionica ricadente nella regione basilicata sono stati rappresentati con estremo dettaglio nell’ambito di uno studio effettuato per un progetto della regione basilicata, finalizzato alla salvaguardia e alla difesa del litorale ionico (boenzi et al., 2002). in particolare è stata prodotta una carta geomorfologica alla scala 1:25.000 in cui si evincono tra l’altro i principali elementi geomorfologici che hanno caratterizzato l’evoluzione della fascia costiera ionica negli ultimi 3.000 anni e i caratteri evolutivi della linea di riva attuale (in arretramento, in equilibrio e in avanzamento) per quanto riguarda invece i caratteri litostratigrafici dei depositi sepolti della piana costiera, questi vengono descritti sulla base di indagini geognostiche effettuate in prossimità della foce del fiume sinni da cotecchia et al. (1969) che, in corrispondenza del paleoalveo il cui riempimento mostra uno spessore di circa 64 m ed un’età non più antica di 11.170 ± 160 anni, descrivono una successione di depositi alluvionali che poggia in discontinuità sul substrato argilloso a hyalinea balthica (argille subappennine). la datazione delle porzioni più recenti della stessa successione si deve al ritrovamento in sondaggi, a circa 3 m di profondità, di resti archeologici che risalgono ad un periodo di tempo compreso tra il vii ed il iii sec. a.c. (boenzi et al., 1987 e citazioni contenute). una prima ricostruzione del tetto del substrato argilloso (argille subappennine) sul quale poggia la successione della piana costiera viene fornita da spilotro (2004) che, attraverso numerosi dati di pozzo, individua una superficie più o meno ondulata posta ad una profondità media di 20÷30 m interrotta, in corrispondenza dei principali corsi d’acqua attuali, da paleoalvei con profondità variabile da poco più di 60 m in corrispondenza del fiume sinni ad oltre 120 m in corrispondenza del fiume bradano. per quanto riguarda l’evoluzione olocenica dei depositi sepolti al di sotto della piana di metaponto capretto (2003), attraverso un rilievo di superficie, l’analisi di nove sondaggi e applicando anche concetti di stratigrafia sequenziale, riconosce una successione spessa al massimo 50 m, in cui sono registrati sia la fase di trasgressione che la successiva fase di stazionamento alto. più recentemente, a seguito dei lavori di aggiornamento della carta geologica d’italia in scala 1:50.000 t. pescatore et al. 311 (foglio 508 “policoro” – progetto carg basilicata) gallicchio et al. (2008) descrivono i nuovi dati di superficie e di profondità ottenuti nell’area compresa tra i fiumi basento e cavone. in base agli stessi dati cilumbriello et al. (in stampa) e sabato et al. (in prep.), grazie anche all’analisi di numerosi sondaggi eseguiti in proprio e recuperati da enti pubblici e di ricerca, propongono una correlazione e suddivisione dei depositi sepolti riconoscendo in particolare un corpo (piana costiera sepolta – pcs) intercalato tra il “substrato” ed il prisma olocenico. tale corpo, irregolare, discontinuo e a geometria complessa, possiede spessori molto variabili, fino ad un massimo di circa 70 m in corrispondenza di paleoincisioni, mentre nelle aree intervallive è spesso pochi metri e mostra geometria cuneiforme. 3. stratigrafia dei depositi affioranti il rilevamento geologico svolto nella piana metapontina ha permesso di individuare e cartografare differenti unità litostratigrafiche di età variabile dal pleistocene superiore all’olocene. per quanto riguarda i sedimenti riferiti in letteratura al deposito marino terrazzato più basso, quello posto a ridosso dell’area costiera, e di età pleistocene superiore, si è fatto riferimento alla suddivisione stratigrafica utilizzata nella nuova cartografia geologica del f° 508 policoro in scala 1:50.000 (sabato et al., in prep.); pertanto tali depositi risultano riferibili ai “depositi sabbioso-conglomeratici dei prismi costieri regressivi”, suddivisi in tre unità informali indicate con i termini di “sabbie e conglomerati di policoro”, “sabbie e conglomerati di masseria ricotta”, e “prodotto eluviale”. i restanti depositi, indicati come “depositi della piana di metaponto” sono invece stati distinti in “depositi continentali” e “depositi di transizione”. i “depositi continentali” sono di età olocenica, e sono stati suddivisi in: “deposito alluvionale delle aree esondabili”, “deposito lacustre e/o palustre”, “deposito alluvionale recente ed attuale” e “coltre eluvio colluviale”. i “depositi di transizione”, anche questi olocenici, si distinguono in una serie di sistemi deltizi e di spiaggia/duna, dove quelli più antichi sono più interni ed ormai abbandonati, in quanto non più attivi, mentre quelli attuali sono prospicienti alla linea di costa. si sottolinea che, per i nomi attribuiti alle unità e per le sigle utilizzate, si è fatto riferimento alle indicazioni fornite dall’ispra, riportate nei quaderni del servizio geologico d’italia (s.g.n., 1992; 1994; 1995; 1996; 1997; 2003 e successivi aggiornamenti). per le attribuzioni agli ambienti sedimentari si è invece fatto riferimento alle suddivisioni utilizzate da massari (1988) in un lavoro relativo alle facies paraliche. 3.1 depositi sabbioso-conglomeratici dei prismi costieri regressivi come detto, nell’area studiata i “depositi sabbioso-conglomeratici dei prismi costieri regressivi” sono suddivisi in tre unità litostratigrafiche. le prime due sono riferibili alle “sabbie e conglomerati di policoro” (ocr) e alle “sabbie e conglomerati di masseria ricotta” (rit). queste unità presentano una morfologia terrazzata, nel senso che sono delimitate superiormente da una superficie pianeggiante e frontalmente da una scarpata che corre parallelamente alla linea di riva della costa ionica. le unità litostratigrafiche su indicate corrispondono, secondo la cartografia geologica ufficiale al terrazzo marino del 7° ordine sensu vezzani (1967) o al terrazzo marino del i ordine sensu brückner (1980a; 1980b; 1982). in discordanza su entrambe le unità si osserva un “prodotto eluviale” (b6) sabbioso-ghiaioso di esiguo spessore e scarsa continuità laterale. l’età dei depositi che costituiscono i prismi costieri regressivi è riferita in letteratura al pleistocene superiore (opp. cit.). 3.1.1 sabbie e conglomerati di policoro (ocr) questa unità affiora in corrispondenza di una fascia che corre lungo il limite occidentale dell’area rilevata ed è limitata superiormente da un ripiano terrazzato che si sviluppa tra le quote di circa 25 m (verso mare) e 35 m s.l.m. (verso l’entroterra); tale ripiano è interrotto trasversalmente in corrispondenza delle incisioni dei principali corsi d’acqua che sfociano sulla costa ionica. gli affioramenti principali sono rappresentati essenzialmente da depositi sabbioso-conglomeratici, con uno spessore massimo di 15 m. lo studio stratigrafico-sedimentologico effettuato lungo alcune sezioni stratigrafiche (cilumbriello, 2008; sabato et al., in prep.) ha permesso di riconoscere associazioni di facies variabili dal marino poco profondo al continentale e di suddividere la successione delle “sabbie e conglomerati di policoro” in due porzioni: una porzione inferiore costituita essenzialmente da un’alternanza di sabbie e lenti ghiaiose per uno spessore medio di circa 6 m, ed una porzione superiore costituita da un corpo conglomeratico clinostratificato con uno spessore medio di circa 4 m passante a depositi prevalentemente sabbiosi spessi circa 5 m. la porzione inferiore è caratterizzata da sabbie medio-fini a laminazione obliqua concava a piccola e grande scala e rari ciottoli allineati lungo le lamine. localmente le sabbie contengono lenti siltose e/o argillose spesse pochi centimetri. le lenti ghiaiose, a base erosiva e con spessori variabili fino a un massimo di 70 cm, sono a tessitura clasto-sostenuta, e in genere disorganizzate, con ciottoli eterometrici (da piccoli ciottoli a rari massi) e di forma arrotondata (subsferici soprattutto, ma anche appiattiti). sia nei sedimenti sabbiosi che nelle lenti ciottolose, si rinviene una fauna mal conservata, all’interno della quale è possibile riconoscere bivalvi disarticolati, talora come modelli o gusci parzialmente disciolti oltre a modelli di gasteropodi indeterminabili. i bivalvi sono rappresentati da aequipecten opercularis, acanthocardia tuberculata, ostrea edulis, glycymeris sp., oltre che da specie indeterminabili delle famiglie veneridae e tellinidae. in base ai caratteri di facies questi depositi si possono attribuire ad ambienti di spiaggia sommersa. la porzione superiore si apre con depositi conglomeratici clinostratificati, immergenti verso mare con angoli variabili da un massimo di 25° (parte basale) fino a pochi gradi (parte alta). tali depositi contengono ciottoli ben selezionati, appiattiti ed embriciati; inoltre sono presenti rare intercalazioni di strati sabbiosi, a geometria cuneiforme. i caratteri di facies descritti permettono di attribuire questi depositi ad ambienti di avanspiaggia ghiaiosa. la successione si chiude con sabbie molto stratigrafia dei depositi pleistocenico-olocenici dell’area costiera ... 312 fini, in genere massive con rare intercalazioni di lenti ghiaiose per uno spessore di circa 5 m. questi depositi vengono attribuiti ad ambienti di piana alluvionale. l’età di questa unità può essere genericamente riferita al pleistocene superiore (brückner, 1980a; 1980b; 1982). 3.1.2 sabbie e conglomerati di masseria ricotta (rit) i depositi relativi alle ”sabbie e conglomerati di masseria ricotta” si rinvengono in un’area di limitata estensione a partire dalla destra orografica del torrente cavone fino a no di metaponto (nei pressi della necropoli). costituiscono una stretta fascia che corre circa parallelamente all’attuale linea di costa ed è limitata superiormente da un ripiano terrazzato che si sviluppa tra le quote di 10 m (verso mare) e 15 m s.l.m. (verso l’entroterra). i depositi sottostanti tale ripiano sono costituiti da una successione sabbioso-conglomeratica con spessore massimo di circa 13 m. l’analisi litostratigrafica effettuata lungo alcune sezioni stratigrafiche (cilumbriello, 2008; sabato et al., in prep.) ha messo in evidenza che la successione è costituita da associazioni di facies riferibili ad ambienti variabili dal marino poco profondo al continentale. in particolare, nell’ambito di tale unità, sono state riconosciute una porzione inferiore prevalentemente sabbiosa ed una porzione superiore prevalentemente conglomeratica. la porzione inferiore, di spessore variabile da un paio di metri a circa una decina di metri, è costituita da sabbie a granulometria da fine a molto fine, con laminazione da obliqua a basso angolo (hummocky crossstratification) a piano-parallela, con intercalazioni di strati argillosi, che passano verso l’alto a sabbie mediofini, con lenti ghiaiose a base erosiva. all’interno si rinviene una fauna molto mal conservata. sono presenti modelli di bivalvi (cardiidae, veneridae e tellinidae), oltre a gusci disarticolati di ostreidae. nell’insieme questi depositi sono stati attribuiti ad ambienti di spiaggia sommersa. la porzione superiore è costituita da depositi prevalentemente conglomeratici con rare intercalazioni di strati sabbiosi, con uno spessore variabile da circa 1 m a 5÷6 m. tale porzione è clinostratificata, e caratterizzata da clinoformi inclinati verso mare con angoli variabili dal basso verso l’alto da 22° a 3°. complessivamente questi depositi sono ben organizzati e costituiti da ciottoli ben selezionati, ben appiattiti e ben embriciati. gli strati sabbiosi sono costituiti da sabbie medio-fini, ben selezionate e a laminazione obliqua planare a basso angolo. a luoghi all’interno di questi strati si rinvengono gusci di bivalvi interi (glycymeris sp., ostrea edulis) ed in frammenti. in base all’analisi di facies questi depositi sono attribuiti ad ambienti di avanspiaggia ghiaiososabbiosa. localmente, su questi depositi si rinvengono, con spessore inferiore al metro, depositi argillosi, ricchi di frustoli vegetali, in genere massivi e fortemente alterati, e depositi sabbiosi, con spessori dell’ordine di un paio di metri con rare intercalazioni di strati ciottolosi a base erosiva. nell’insieme tali depositi sono riferibili ad ambienti continentali ed in particolare, i primi possono essere attribuiti ad ambienti lagunari e/o di retrospiaggia mentre i secondi ad ambienti di piana alluvionale. questa unità è stata attribuita al pleistocene superiore (brückner, 1980a; 1980b; 1982). 3.1.3 prodotto eluviale (b6) si rinviene in maniera discontinua nelle aree depresse e/o sub-pianeggianti costituite dalle superfici terrazzate dei depositi sabbioso-conglomeratici delle precedenti unità, sulle quali poggia in erosione; si tratta di sabbie limose di colore rossastro con sottili livelli ghiaiosi. i clasti hanno dimensioni dell’ordine del centimetro, sono poligenici e mediamente arrotondati. lo spessore di tale deposito è al massimo di circa un paio di metri. l’età è riferibile al pleistocene superiore. 3.2 depositi della piana di metaponto i “depositi della piana di metaponto” si sviluppano essenzialmente dalla base della scarpata che delimita inferiormente l’area dei prismi costieri regressivi fino alla linea di riva della costa ionica. si distinguono in: “depositi continentali” e “depositi di transizione”. 3.2.1 depositi continentali la suddivisione dei depositi continentali, eseguita essenzialmente sulla base dei meccanismi genetici e della posizione stratigrafica, ha permesso di distinguere le seguenti unità di età olocenica: “deposito alluvionale delle aree esondabili”, “deposito lacustre e/o palustre”, “deposito alluvionale recente ed attuale” e “coltre eluvio colluviale”. l’origine di tali depositi è dovuta prevalentemente all’attività dei principali corsi d’acqua presenti nell’area (torrente cavone e fiumi basento e bradano), nonché alla presenza di laghetti effimeri ed aree palustri di limitata estensione, che si sviluppano in prossimità delle foci dei fiumi e/o nelle aree interdunari e nelle aree depresse della piana alluvionale; solo in alcuni casi tali depositi derivano da processi di degradazione ed erosione di sedimenti relativamente più interni ed antichi. 3.2.1.1 deposito alluvionale delle aree esondabili (bn) tale deposito occupa le porzioni interne della piana metapontina; verso terra si estende oltre la base della scarpata che delimita i depositi dei prismi costieri regressivi, occupando le incisioni che tagliano trasversalmente i prismi stessi, mentre verso mare si estende fino alle spalle dei cordoni dunari più interni dei sistemi spiaggia/duna abbandonati. il settore occupato da questo deposito è rappresentato da un’area pianeggiante che sebbene più elevata di alcuni metri rispetto all’alveo dei corsi d’acqua, può essere soggetta, anche se parzialmente, ad alluvionamenti in occasione di eventi meteorici eccezionali. i caratteri litostratigrafici sono stati osservati in corrispondenza dei sondaggi effettuati nell’area in oggetto; tale deposito, il cui spessore risulta dell’ordine di pochi metri (da 3÷4 m fino a circa 10 m), è costituito essenzialmente da strati spessi al massimo un paio di metri di sabbie a granulometria molto fine e/o medio-fine, con una caratteristica colorazione giallastra, a cui si intercalano livelli ghiaiosi discontinui e di spessore limitato. al suo interno si riconoscono resti di gusci di gasteropodi terrestri (helicidae) e noduli calcarei. in prossimità dei principali corsi d’acqua (torrente cavone, fiumi basento e bradano) si riconoscono corpi limoso-argillosi. i caratteri di facies permettono di riferire tale deposito ad ambienti di origine alluvionale, ed in particolare i corpi limoso-argillosi sono relativi al riempimento di alvei meandriformi abbandonati. localmente, t. pescatore et al. alla base della scarpata dei depositi sabbioso-conglomeratici dei prismi costieri regressivi il deposito alluvionale delle aree esondabili presenta chiari caratteri morfologici riferibili a corpi di conoide alluvionale, che si sviluppano in corrispondenza dello sbocco nella piana di piccoli affluenti dei principali corsi d’acqua. tali corpi sono stati indicati in carta con l’apposito simbolo suggerito dai quaderni del servizio geologico d’italia (s.g.n., 1992, 1994; 1995; 1996; 1997; 2003 e successivi aggiornamenti). l’età di tale deposito è riferibile all’olocene; in particolare, ad una profondità di 3 m sono stati rinvenuti resti archeologici dell’età greca, riferibili a 3.000 anni fa (boenzi et al., 1987). 3.2.1.2 deposito lacustre e/o palustre (e2, e3) tale deposito si ritrova nelle aree interdunari ed in prossimità delle aree di foce abbandonate (torrente cavone e fiumi basento e bradano). si tratta di sedimenti sabbiosi e/o argilloso-siltosi. le sabbie presentano una colorazione nerastra, granulometria da grossolana a medio-fine e sono ricche di resti vegetali, oltre che di lamellibranchi interi (cerastoderma glaucum) ed in frammenti e di gasteropodi in frammenti. i sedimenti argilloso-siltosi hanno colore grigio scuro, sono molto alterati e da quanto si evince dall’analisi dei sondaggi che li hanno attraversati, costituiscono strati spessi da meno di mezzo metro ad un paio di metri. la porzione affiorante, nel periodo estivo, è caratterizzata da strutture di essiccamento (mud cracks). tali sedimenti rappresentano antichi bacini lacustri prosciugati e bonificati (e2), ma ancora oggi soggetti ad allagamenti durante fenomeni di precipitazioni intense, e/o paludi erbacee stagionali (e3), talvolta presenti tra un cordone litorale e l’altro. lo spessore è di circa 2 m. l’età di questo deposito è riferibile all’olocene. 3.2.1.3 deposito alluvionale recente ed attuale (b) tale deposito, spesso pochi metri, è localizzato lungo le aste dei principali fiumi che attraversano l’area in oggetto (torrente cavone, fiumi basento e bradano) e ne rappresenta le barre e le aree di esondazione. si tratta di sabbie limose e limi con intercalazioni di lenti ghiaiose di modesta estensione. localmente le aree di affioramento risultano antropizzate. l’età è stata riferita all’olocene. 3.2.1.4 coltre eluvio colluviale (b2) si rinviene nella zona di passaggio tra i depositi sabbioso-conglomeratici dei prismi costieri regressivi e i depositi della piana di metaponto. si tratta di limi e sabbie di colore rosso bruno, e di ghiaie costituite da clasti poligenici da arrotondati a spigoli vivi, con dimensioni variabili da pochi millimetri al decimetro. lo spessore è dell’ordine metrico. l’età è stata riferita all’olocene. 3.2.2 depositi di transizione tali depositi rappresentano sistemi costieri legati all’attività dei corsi d’acqua e dei processi marini che hanno agito durante l’olocene, fino all’attuale. si tratta quindi di una serie di depositi deltizi e depositi del sistema spiaggia/duna, che ringiovaniscono procedendo dall’interno verso la costa. insieme rappresentano una fascia stretta ed allungata parallelamente alla costa. in particolare sono state distinte le seguenti unità: “deposito deltizio abbandonato”, ”deposito di spiaggia/duna abbandonato”, “deposito deltizio attuale”, ”deposito di spiaggia/duna attuale”. le prime tre unità sono riferibili alle “sabbie e silt di metaponto”, l’ultima unità al “deposito di spiaggia attuale”, distinti nell’ambito del f° 508 policoro (sabato et al., in prep.). 3.2.2.1 deposito deltizio abbandonato (g1b) tale deposito si riconosce in prossimità delle foci dei principali corsi d’acqua ed è costituito da sedimenti siltoso-argillosi con intercalazioni sabbiose e da sabbie formatisi in seguito a fenomeni di esondazione alla foce dei principali corsi d’acqua (g1b). si distinguono inoltre aree acquitrinose e palustri (e3b) costituite da sedimenti siltoso-argillosi e corpi prevalentemente sabbiosi che rappresentano antiche barre di foce (fb). lo spessore massimo, osservato in trincea, è di pochi metri. l’età è riferibile all’olocene. 3.2.2.2 deposito di spiaggia/duna abbandonato (g2, d)n questa unità caratterizza una fascia di ampiezza variabile da poche centinaia di metri al chilometro, ed è compresa tra il deposito alluvionale delle aree esondabili (bn) e il deposito di spiaggia/duna attuale. si tratta di depositi sabbiosi e siltoso-argillosi (g2, d)n, riferibili ad antichi sistemi deposizionali formati da cordoni dunari sabbiosi e aree retrodunali siltoso-argillose, difficilmente distinguibili gli uni dalle altre a causa dell’intensa antropizzazione. solo localmente è stato possibile distinguere e cartografare diversi ordini di cordoni dunari sabbiosi abbandonati caratterizzati essenzialmente dalla presenza di dune eoliche con altezze dell’ordine di 4÷5 m intervallate da aree depresse, sedi attualmente di acquitrini effimeri; in tal caso ciascun ordine è stato indicato in carta con le sigle (g2, d)b-g, con le lettere a pedice che indicano in ordine alfabetico i cordoni litorali dai più recenti ai più antichi. in genere si tratta di sabbie medio-fini che si alternano a sabbie fini siltose, al cui interno si rinvengono frequenti bivalvi appartenenti alle famiglie cardiidae, veneridae e tellinidae, e rari ciottoli. il deposito di spiaggia/duna abbandonato più interno (g2, d)g è caratterizzato da sabbie medio-grossolane, debolmente arrossate, debolmente cementate (località tufarelle) e ricche in frammenti di gusci di bivalvi. lo spessore è di circa 5 m. l’età è riferibile all’olocene. 3.2.2.3 deposito deltizio attuale (g1a) tale unità si ritrova in corrispondenza delle foci dei principali corsi d’acqua presenti nell’area ed è rappresentata da sedimenti siltoso-argillosi con intercalazioni sabbiose che costituiscono l’attuale zona di esondazione alla foce dei principali corsi d’acqua (g1a). localmente si distinguono sedimenti prevalentemente limosi costituenti aree acquitrinose e palustri (e5) e sedimenti prevalentemente sabbiosi costituenti barre di foce emerse (fa). lo spessore è di pochi metri. l’età è riferibile all’olocene. 3.2.2.4 deposito di spiaggia/duna attuale (g2, d)a tale deposito si ritrova lungo una fascia costiera larga da pochi metri fino ad un massimo di alcune deci313stratigrafia dei depositi pleistocenico-olocenici dell’area costiera ... ne di metri, che corre parallelamente alla linea di riva. la parte più interna è rappresentata da dune eoliche (da) la cui altezza è di circa 1÷2 m; le dune sono costituite da sabbia fine, le cui strutture sedimentarie, osservabili in corrispondenza dei tratti di costa in erosione, sono rappresentate essenzialmente da laminazione obliqua ad alto angolo. verso mare si osserva il tratto di costa rappresentato dalla spiaggia emersa (g2a), caratterizzata da un profilo molto dolce e costituita da sabbia medio-fine ben selezionata, a laminazione da piano-parallela ad obliqua, leggermente inclinata verso terra. in questo deposito si ritrovano concentrazioni di bivalvi delle famiglie cardiidae, veneridae e tellinidae. lo spessore è dell’ordine di un paio di metri. tale deposito è riferibile all’olocene. 4 . i depositi sepolti della piana di metaponto nell’ambito del progetto di ricerca richiamato nell’introduzione, sono stati eseguiti cinque sondaggi a carotaggio continuo. due sondaggi sono stati eseguiti dall’unità operativa dell’università di bari nell’area compresa tra il fiume basento ed il torrente cavone, lungo la strada provinciale che collega la ss 106 al “lido quarantotto”, in località “panetta”: sondaggio lazazzera (lz), e sondaggio casa sotto le stelle (cs). tre sondaggi sono stati eseguiti dall’unità operativa dell’università del sannio a nord del fiume bradano: sondaggio ginosa 01 (s1), sondaggio ginosa 02 (s2) e sondaggio ginosa 03 (s3) (fig. 1d). sulle carote recuperate è stata eseguita un’analisi litostratigrafica e sono stati osservati i caratteri di facies; inoltre è stata effettuata una datazione radiometrica con il metodo del 14c lungo il sondaggio cs. 4.1 sondaggio lazazzera (lz) il sondaggio lazazzera (lz) (fig. 2) è stato perforato ad una distanza di circa 3,5 km dall’attuale linea di costa, ad una quota topografica di 6 m s.l.m., e per una profondità di 52 m raggiungendo la quota di -46 m. sulla carota recuperata è stata effettuata un’analisi stratigrafico-sedimentologica che ha permesso di suddividere in due porzioni la successione sedimentaria attraversata. a partire dalla profondità di 52 m fino a quella di 19 m, si rinviene la porzione inferiore, spessa complessivamente 33 m, dei quali i primi 13 m sono costituiti da 314 fig. 2 colonna stratigrafica ricostruita lungo le carote del sondaggio lz; al lato sono riportati i principali caratteri di facies, le associazioni di facies e i principali ambienti deposizionali. per l’ubicazione vedi fig. 1d. la scala granulometrica utilizzata è quella di wentworth (1922) modificata da bosellini et al. (1989). stratigraphic column and interpretation of facies associations from borehole lz; location in fig. 1d. we used the wentworth (1922) granulometric scale, modified by bosellini et al. (1989). t. pescatore et al. depositi siltosi con intercalazioni di livelli sabbiosi nei primi 10 m, mentre i restanti 20 m sono rappresentati da depositi prevalentemente sabbiosi. i depositi siltosi sono perlopiù massivi e raramente laminati, e spesso si presentano intensamente bioturbati. i depositi sabbiosi presentano nei primi 4 m sottili intercalazioni siltose, possiedono granulometria molto fine ed una laminazione piano-parallela, a luoghi interrotta da bioturbazione. complessivamente questa porzione di successione risulta inoltre ricca di gusci di lamellibranchi e di gasteropodi in frammenti, e contiene resti di ostracodi indeterminabili e radioli di echinidi. il contenuto microfossilifero è invece scarso, rappresentato perlopiù da foraminiferi bentonici fra cui ammonia beccarii, elphidium crispum, textularia agglutinans, valvulineria bradyana, e rari esemplari di hyalinea balthica (sabato et al., in prep.). in erosione sui depositi della porzione inferiore si osserva, a partire dalla profondità di 19 m, la porzione di successione superiore, più grossolana, che si apre con un livello di spessore decimetrico costituito in prevalenza da ciottoli delle dimensioni medie di 3÷4 cm, arrotondati, con abbondante matrice sabbiosa e frammenti di macrofossili. i successivi 4 m, rinvenuti fino alla profondità di circa 15 m, sono costituiti da sabbie medio-fini ricche in frammenti di molluschi indeterminabili, con rare intercalazioni di livelli ciottolosi nella parte alta, e passanti ad un sottilissimo livello siltoso. al di sopra si osservano per uno spessore di circa 1 m sabbie e ghiaie cui seguono 9 m di sabbie, rinvenute fino a circa 6 m di profondità, a granulometria da fine a medio-grossolana, laminate, e con intercalazioni di livelli ghiaiosi spessi qualche centimetro. questi ultimi sono costituiti da ciottoli arrotondati (sferici ed appiattiti) e di dimensioni variabili da 1 cm a 7÷8 cm. all’interno di questi depositi sono stati rinvenuti gusci di bivalvi in frammenti. gli ultimi 6 m della porzione superiore sono rappresentati da sabbie da medie a molto fini con ciottoli sparsi, che verso l’alto passano ad argille siltose grigio-verdastre spesse circa 2,5 m, con rari ciottoli e materiale carbonioso. in base ai caratteri di facies descritti, i depositi siltosi e quelli sabbiosi, che costituiscono la porzione inferiore della successione analizzata, possono essere attribuiti rispettivamente ad ambienti di piattaforma e di transizione alla piattaforma, e ad ambienti di spiaggia sommersa. il livello ghiaioso, posto in corrispondenza della superficie erosiva alla base della porzione superiore della successione è stato interpretato come un deposito residuale (lag). per quanto riguarda invece i restanti depositi appartenenti alla porzione superiore, le sabbie medio-fini con rari livelli ghiaiosi presentano caratteri di facies riferibili ad ambienti di avanspiaggia, i successivi depositi ghiaioso-sabbiosi e sabbioso-siltosi mostrano invece caratteri di facies riferibili ad ambienti di spiaggia sommersa-avanspiaggia, ed infine gli ultimi 6 m rappresentati da sabbie passanti ad argille, sono riferibili ad ambienti continentali, di piana alluvionale e/o di palude. 4.2 sondaggio casa sotto le stelle (cs) il sondaggio casa sotto le stelle (cs) (fig. 3) è stato perforato a circa 2,5 km dall’attuale linea di costa, per una profondità di circa 120 m a partire dalla quota topografica di 4 m s.l.m., e raggiungendo la quota di -116 m. in base ai caratteri litostratigrafici e di facies osservati, la successione sedimentaria attraversata da tale sondaggio può essere suddivisa in due porzioni. la porzione inferiore, spessa circa 76 m, e osservata a partire dalla profondità di 120 m fino a quella di 44 m, è rappresentata da strati argilloso-siltosi e siltoso-argillosi, generalmente massivi ed intensamente bioturbati, ai quali si alternano strati sabbiosi spessi da pochi centimetri fino a qualche metro, fittamente laminati. il contenuto macrofossilifero è rappresentato in prevalenza da frammenti di gusci di bivalvi e gasteropodi marini. in questa porzione di successione si sono rinvenuti numerosi foraminiferi, oltre a nannofossili calcarei; in base alla presenza di emiliania huxleyi lohmann è stato possibile riferire tali depositi ad un’età non più antica del pleistocene medio (sabato et al., in prep.). la porzione superiore della successione poggia in erosione sui depositi sottostanti ed ha uno spessore di circa 44 m. nell’ambito di questa porzione è possibile effettuare una ulteriore suddivisione in due parti: una basale ed una sommitale. la parte basale è spessa circa 7 m, e si rinviene a partire dalla profondità di 44 m fino a quella di circa 37 m. e’ costituita in basso da uno strato a ciottoli con matrice sabbioso-argillosa e con incrostazioni di carbonato di calcio che verso l’alto passa a depositi siltosi con sottilissime intercalazioni argillose di colore grigio-scuro per uno spessore complessivo di 1,5 m; su questi depositi si osserva un’alternanza di strati sabbiosi e strati ghiaiosi con frammenti di gusci di lamellibranchi, per uno spessore complessivo di circa 5,5 m. la parte sommitale, spessa circa 37 m, è costituita, per uno spessore di circa 4 m da depositi sabbiosi a granulometria da molto fine a fine con intercalazioni di livelli ghiaiosi e presenza di gusci interi ed in frammenti di bivalvi e gasteropodi marini; seguono, a partire dalla profondità di circa 33 m, circa 6 m di depositi siltosi con intercalazioni di sottilissimi strati sabbiosi a granulometria molto fine che verso l’alto, fino alla profondità di circa 6 m passano a depositi sabbiosi a granulometria da molto fine a fine e con gusci interi ed in frammenti di bivalvi (tellina sp., spisula subtruncata, chamelea gallina, cerithium sp. e fissidentalium rectum); gli ultimi 6 m circa sono rappresentati da depositi sabbiosi con ciottoli sparsi che verso l’alto passano ad un’alternanza di strati argillosi grigio-verdastri e sabbioso-siltosi con una colorazione giallo-ocra, caratterizzati dalla presenza di gasteropodi terrestri (helicidae) e noduli di carbonato di calcio. su un campione di guscio di un bivalve prelevato ad una profondità di 35 m (campione c6 in fig. 3), è stata effettuata una datazione con il metodo radiometrico del 14c; tale campione ha fornito un’età di 7.562±50 non cal bp (8.510-8350 cal bp; δ13c = -27,6±0.3‰) permettendo di attribuire i primi 35 m della successione attraversata dal sondaggio cs alla parte medio-alta dell’olocene. i caratteri di facies descritti permettono di riferire i depositi argilloso-siltosi e sabbiosi della porzione inferiore della successione ad ambienti di piattaforma e transizione alla piattaforma. la porzione superiore invece mostra nella parte basale, spessa 7÷8 m e formata da silt, argille, sabbie e ghiaie, caratteri di facies riferibili ad ambienti variabili dal continentale (canale fluviale-piana alluvionale-palude) al marino poco profondo (avanspiaggia-retrospiaggia); la parte sommitale della porzione 315stratigrafia dei depositi pleistocenico-olocenici dell’area costiera ... 1 2 3 4 5 6 7 8 9 10 11 12 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 316 fig. 3 colonna stratigrafica ricostruita lungo le carote del sondaggio cs; al lato sono riportati i principali caratteri di facies, le associazioni di facies e i principali ambienti deposizionali. per l’ubicazione vedi fig. 1d. stratigraphic column and interpretation of facies associations from borehole cs; location in fig. 1d. t. pescatore et al. superiore invece è formata da sabbie con livelli ghiaiosi di ambiente di avanspiaggia, passanti verso l’alto a depositi siltosi, sabbiosi, ghiaiosi e argillosi che mostrano un trend shallowing upward, con ambienti variabili dal marino poco profondo (transizione alla piattaformaspiaggia sommersa-avanspiaggia-retrospiaggia) al continentale (piana alluvionale-palude) (fig. 3). 4.3 sondaggio ginosa 01 (s1) il sondaggio ginosa 01 (s1) (fig. 4) è stato eseguito a circa 2 km dalla linea di costa attuale, ad una quota di 4 m s.l.m. e per una lunghezza di 29,5 m raggiungendo la quota di -25,5 m. è caratterizzato dal basso verso l’alto, per i primi 3,4 m da alternanze di strati molto sottili di sabbie fini e silt argillosi (0,3 m) con laminazioni piano-parallele seguite da un livello di argilla siltosa (0,3 m) e, poi, bruscamente da ghiaie sabbiose. queste presentano uno spessore di 0,28 m, la stratificazione e la tessitura originaria non si è preservata, i ciottoli sono spesso scheggiati, frammentati e/o striati in superficie in seguito alle modalità di esecuzione del sondaggio. sulla superficie di alcuni ciottoli si è osservata matrice sabbiosa cementata. da circa 26 m a circa 20 m di profondità si osservano alternanze di strati sottili e molto sottili di sabbie fini siltose (talora laminate e contenenti rari ciottoli con diametro inferiore al centimetro), e di argille siltose. tra 20 m e 15 m, durante l’esecuzione del sondaggio, si sono perse le informazioni sulla stratificazione e le strutture sedimentarie dei depositi, ma le tessiture sembrano essere simili a quelle del livello precedente. tra 15 m e 7,6 m si rinvengono alternanze di strati sottili e molto sottili di sabbie fini siltose (talora laminate e contenenti ciottoli di diametro inferiore al centimetro) e di argille siltose spesso nerastre a causa della presenza di abbondante sostanza organica. piccole valve di lamellibranchi sono presenti da profondità inferiori a 20 m. da 317 fig. 4 colonne stratigrafiche ricostruite lungo le carote dei sondaggi s1 ed s2; al lato sono riportati i principali caratteri di facies, le associazioni di facies e i principali ambienti deposizionali. per l’ubicazione vedi fig. 1d. stratigraphic columns and interpretation of facies associations from boreholes s1 and s2; for location see fig. 1d. stratigrafia dei depositi pleistocenico-olocenici dell’area costiera ... circa 7,5 m a 3,7 m prevalgono depositi ghiaioso-sabbiosi talora con frammenti di gusci di lamellibranchi. il diametro massimo degli elementi ghiaiosi non supera 10 cm e la loro superficie non presenta tracce di cementi o matrice cementata. da 3,7 m al piano campagna si rinvengono sabbie essenzialmente con granulometria media. i depositi osservati da 29,5 m a circa 26 m non si riescono ad interpretare univocamente e, non avendo dati stratigrafici dei depositi sottostanti, potrebbero rappresentare tanto la base della trasgressione quanto includere il passaggio pleistocene-olocene (verosimilmente la parte alta del livello ghiaioso potrebbe includere un conglomerato basale trasgressivo su ghiaie sabbiose debolmente cementate del pleistocene). da 26 m a 20 m di profondità si sono riconosciute associazioni di facies riferibili ad ambienti di spiaggia sommersa inferiore che verso l’alto (da 15 a 3,7 m di profondità dal piano campagna) passano a un sistema deltizio con associazione di facies di fronte deltizio esterno/prodelta prossimale. queste facies a circa 7,5 m di profondità vengono sostituite da quelle di barra rappresentate da depositi ghiaioso-sabbiosi. nella parte alta del sondaggio, a profondità inferiori di 3,7 m, i depositi sabbiosi (sabbie medie ben selezionate) sono stati attribuiti a facies di avanspiaggia. 4.4 sondaggio ginosa 02 (s2) il sondaggio ginosa 02 (s2) (fig. 4) è stato eseguito a circa 100 m dalla linea di costa attuale, a una quota di 4 m s.l.m. e per una lunghezza di 48 m raggiungendo la quota di -44 m. dal basso verso l’alto è caratterizzato, per i primi 6 m, da alternanze in strati molto sottili di sabbie fini siltose e silt argillosi che passano gradualmente a circa 6 m di alternanze in strati molto sottili di silt argillosi e silt da medio a molto fine con una frazione sabbiosa costituita da muscovite. sempre con passaggio graduale da circa 36 m fino a circa 21 m dal piano campagna si osservano strati sottili e molto sottili di sabbie fini siltose, alternati a strati molto sottili di silt sabbiosi e subordinatamente di silt argillosi. seguono, da 21 a 14 m, depositi simili ai precedenti in cui a più altezze si osservano livelli costituiti da sabbie medie, livelli argillosi e talora livelli nerastri ricchi di sostanza organica. da 14 m a 4 m si rinvengono sabbie medio-fini che si alternano a sabbie fini siltose. in queste sabbie sono frequenti valve di lamellibranchi (intere e in frammenti), ciottoletti e laminazione obliqua, laminazione parallela e strati con gradazione normale. tra 4 e 2,9 m seguono sabbie medie ben selezionate. gli ultimi tre metri sono costituiti da sabbie contaminate da materiale antropico. le associazioni di facies riconosciute dal basso sono: di spiaggia sommersa inferiore tra 48 e 42 m, di transizione alla piattaforma tra 42 e 35 m, di spiaggia sommersa tra 35 e 3÷4 m e, infine, di avanspiaggia tra 3÷4 e 0 m. 4.5 sondaggio ginosa 03 (s3) il sondaggio ginosa 03 (s3) (fig. 5) è stato realizzato a circa 2,8 km dalla linea di costa attuale, ad una quota di circa 3 m s.l.m. e per una lunghezza di 45 m raggiungendo una profondità di -42 m. dal basso verso l’alto si osservano, da 45 a 30,5 m dal piano campagna, alternanze di strati sottili e molto sottili di sabbie molto fini, silt debolmente argilloso e silt argilloso in cui si rinvengono frammenti di gusci di lamellibranchi, radioli di echinidi e livelli ricchi in sostanza organica. seguono, da 30,5 m a 19,7 m, alternanze di strati sottili e molto sottili di sabbie fini e sabbie molto fini più o meno siltose. si distinguono laminazioni pianoparallele, spesso si rinvengono resti di lamellibranchi e, a varie altezze, le sabbie sono cementate per spessori di pochi centimetri. da 19,7 m a 13,2 m si osservano sabbie ghiaiose più o meno cementate e arrossate; sulla superficie dei ciottoli oltre alle patine di ossidi di ferro sono presenti resti di cemento bruno microcristallino 318 fig. 5 colonna stratigrafica ricostruita lungo le carote del sondaggio s3; al lato sono riportati i principali caratteri di facies, le associazioni di facies e i principali ambienti deposizionali. per l’ubicazione vedi fig. 1d. stratigraphic column and interpretation of facies associations from borehole s3; for location see fig. 1d. t. pescatore et al. carbonatico a menisco e microstalattitico. da 13,2 m a 12,7 m si osservano sabbie da grossolane a medio-fini ricche in frammenti indeterminabili di lamellibranchi e gasteropodi e di sostanza organica (si distinguono anche resti vegetali). da 12,7 m a 9,7 m, gradualmente, si passa ad argilla e argilla siltosa di colore grigio scuro con valve di lamellibranchi (cerastoderma glaucum). seguono circa 0,2 m di torba con gusci di gasteropodi terrestri. da 9,5 m a 6,5 m si rinvengono sabbie medie e fini da ben selezionate a moderatamente selezionate. segue un nuovo livello di circa 0,25 m di torba e da 6,2 m a 0 m si osservano argille siltose più o meno ricche di sostanza organica, con resti di gusci di gasteropodi terrestri e, nella parte medio-alta, noduli calcarei. in questo sondaggio la superficie che limita superiormente le sabbie ghiaiose arrossate e cementate di ambiente di avanspiaggia, rappresenta il limite superiore dei depositi del pleistocene superiore, e pertanto sono stati attribuiti all’olocene solo i primi 13,2 m. al di sopra di questa superficie i depositi compresi tra 13,2 m e 9,5 m rappresentano facies principalmente lagunari che si chiudono con un deposito palustre. tra 9,5 m e 6,5 m, le sabbie medie e fini testimoniano facies di avanspiaggia/retrospiaggia. da 6,5 m a 0 m i depositi argilloso-siltosi con alla base un livello ricco di resti vegetali costituiscono dei depositi palustri che, verso l’alto, presentano caratteri di facies di piana alluvionale. 5. correlazione e stratigrafia dei depositi sepolti lo studio dei caratteri litostratigrafici e di facies dei sondaggi eseguiti, nonché la loro correlazione, hanno permesso di suddividere la successione sedimentaria presente nel sottosuolo della piana di metaponto in tre unità sovrapposte (figg. 6, 7), separate da superfici di discontinuità ben riconoscibili, rappresentate da superfici erosive messe in evidenza anche da bruschi contrasti di facies. l’unità in posizione geometrica inferiore è indicata con il termine di “substrato”; quella intermedia, a geometria cuneiforme in base all’interpretazione proposta in cilumbriello et al. (in stampa), poggia in discontinuità sul substrato, ed è indicata con il termine di “depositi della piana sepolta di metaponto” (psm); la terza unità, la cui porzione sommitale rappresenta l’insieme dei depositi affioranti nella piana costiera metapontina, è riferibile ai “depositi della piana di metaponto” (pm), e poggia in discontinuità sia sul substrato che sui depositi della piana sepolta di metaponto (figg. 6, 7). il substrato è stato perforato per uno spessore variabile fino ad un massimo di circa 76 m (sondaggio cs nelle figg. 3, 6, 7), ed è costituito da sedimenti argilloso-siltosi con intercalazioni sabbiose che verso l’entroterra e verso l’alto passano a depositi sabbiosoconglomeratici (nel sondaggio s3) o sabbiosi (nel sondaggio lz) (figg. 5,7). tali depositi sono riferibili ad ambienti variabili dalla piattaforma all’avanspiaggia. il limite inferiore del substrato non è stato ritrovato, mentre il limite superiore è stato individuato grazie al riconoscimento nei sondaggi s3, lz e cs di una chiara superficie di erosione (se in figg. 2, 3, 6, 7) posta ad una profondità variabile da 13 m (s3) a 44 m (cs). questa superficie è evidenziata nel sondaggio s3 (fig. 5) dalla sovrapposizione di depositi sabbiosi e siltosi di ambiente lagunare dell’unità pm sui depositi sabbiosoghiaiosi di ambiente di avanspiaggia del substrato. procedendo verso mare invece, tale superficie è evi319 fig. 6 sezioni geologiche (ab, cd) effettuate nell’area di studio, realizzate sia utilizzando dati di superficie che di sottosuolo. per l’ubicazione vedi fig. 1d. geological sections (ab, cd) performed in the study area, using surface and core-drillings data; for location see fig. 1d. stratigrafia dei depositi pleistocenico-olocenici dell’area costiera ... 320 f ig . 7 c o rr e la zi o n i st ra ti g ra fic h e e a ss o c ia zi o n i d i fa c ie s lu n g o le se zi o n i g e o lo g ic h e a ’b e c ’d (v e d i fig . 6 e c a rt a g e o lo g ic a a lle g a ta ) d e i “d e p o si ti d e lla p ia n a se p o lt a d i m e ta p o n to ” (p sm ) d e lp le is to c e n e su p e ri o re e d e i“ d e p o si ti d e lla p ia n a d im e ta p o n to ” (p m ), d ie tà o lo c e n ic a . s tr at ig ra p h ic c o rr e la ti o n s an d fa c ie s as so c ia ti o n s al o n g th e a ’b an d c ’d g e o lo g ic al se c ti o n s (s e e f ig . 6 an d g e o lo g ic al m ap ) p e rf o rm e d in th e u p p e r p le is to c e n e b u ri e d m e ta p o n to p la in d e p o si ts (p sm ) an d in th e h o lo c e n e m e ta p o n to p la in d e p o si ts (p m ). t. pescatore et al. denziata dal deposito residuale (lag) individuato nel sondaggio lz (figg. 2, 7) alla profondità di circa 19 m alla base dell’unità pm, in erosione sui sottostanti depositi di spiaggia sommersa del substrato. nel sondaggio cs infine, la stessa superficie mette a contatto depositi siltoso-sabbiosi di ambiente di transizione alla piattaforma appartenenti al substrato, con depositi di ambiente continentale dell’untà psm (fig. 3, 7). l’età di tale substrato è riferibile al pleistocene medio parte alta, in base alla presenza di emiliania huxley lohmann rinvenuta nelle porzioni argillose della carota del sondaggio cs, e dubitativamente al pleistocene superiore, età cui sono riferibili i depositi sabbioso-conglomeratici dei prismi costieri regressivi più recenti (sabato et al., in prep.). in erosione sul substrato, per mezzo della superficie se si rinviene l’unità dei “depositi della piana sepolta di metaponto” (psm), riscontrata esclusivamente nel sondaggio cs (figg. 3, 6), per uno spessore di circa 7 m. tale unità risulta costituita da depositi sabbiosoghiaiosi con associazioni di facies variabili dal continentale al marino poco profondo. dalla correlazione stratigrafica e da altri dati derivanti dalla stratigrafia di numerosi sondaggi si evince che l’unità psm ha una geometria a cuneo con chiusura verso terra (figg. 6, 7). in base alla posizione stratigrafica ed ai dati raccolti, tale unità può essere riferita al pleistocene superiore (cilumbriello et al., in stampa). infine, l’unità dei depositi della piana di metaponto (pm) viene a contatto con i sottostanti depositi dell’unità psm per mezzo della superficie st che verso monte intercetta il substrato, ponendo a diretto contatto quest’ultimo con l’unità dei “depositi della piana di metaponto” (pm), (figg. 2, 5, 6, 7). tale superficie si abbassa spostandosi verso mare, tanto che nel sondaggio s3 si rinviene a 13 m di profondità, mentre distalmente supera almeno la profondità di 30 m e 48 m rispettivamente nei sondaggi s1 e s2, in quanto non viene intercettata dagli stessi. i depositi dell’unità pm raggiungono uno spessore di almeno 48 m (sondaggio s2 in figg. 4, 6, 7), e sono rappresentati alla base da sabbie ghiaiose (sondaggi cs e s1) riferibili ad associazioni di facies di avanspiaggia, passanti verso l’alto a sedimenti siltoso-sabbiosi e sabbioso-ghiaiosi, di ambiente variabile da piattaforma a continentale (fig 7). nell’ambito dell’unità pm è possibile riconoscere, quindi, un ciclo completo trasgressivo-regressivo e la superficie st che delimita inferiormente tale unità, rappresenta una superficie di trasgressione (fig. 7). inoltre, la datazione effettuata attraverso il metodo radiometrico 14c (7.562±50 bp) sui depositi del sondaggio cs, permette di attribuire all’olocene i depositi dell’unità pm. 6. conclusioni nel tratto di costa compreso tra la foce del torrente cavone e l’abitato di marina di ginosa, lungo l’area costiera di metaponto, sono stati realizzati un rilevamento geologico di dettaglio, oltre a cinque perforazioni a carotaggio continuo che hanno portato alla realizzazione di una carta geologica dell’area, in scala 1:25.000, corredata da importanti informazioni sui depositi sepolti. nell’ambito dei depositi affioranti è stato possibile individuare due principali unità: “depositi sabbioso-conglomeratici dei prismi costieri regressivi” di età pleistocene superiore, e “depositi della piana di metaponto” di età olocene. all’interno di tali unità sono state effettuate ulteriori suddivisioni, permettendo di delineare un quadro stratigrafico dettagliato e differente da quello attualmente vigente in letteratura. i depositi sabbioso-conglomeratici dei prismi costieri regressivi sono stati distinti in tre unità. le prime due rappresentano dei prismi sedimentari con una morfologia terrazzata, formatisi in seguito ad interazioni fra oscillazioni del livello del mare e sollevamento regionale. nell’area studiata tali depositi sono rappresentati da due unità litostratigrafiche riferibili alle “sabbie e conglomerati di policoro” e alle “sabbie e conglomerati di masseria ricotta“. la terza unità, in erosione su entrambe, è formata da un “prodotto eluviale” discontinuo e di esiguo spessore, rappresentato da sabbie limose di colore rossastro con sottili livelli ghiaiosi. in base a dati di letteratura, queste unità sono riferibili al pleistocene superiore. verso mare ed in posizione meno elevata rispetto ai depositi sabbioso-conglomeratici dei prismi costieri regressivi si rinvengono i “depositi della piana di metaponto”, di età olocenica, all’interno dei quali è stato possibile individuare differenti unità litostratigrafiche rappresentative di altrettanti sistemi deposizionali. a partire dall’entroterra verso la costa sono stati distinti i “depositi continentali” ed i “depositi di transizione”. i depositi continentali sono rappresentati da depositi eluviali, fluviali, lacustri e palustri, quelli di transizione sono costituiti da depositi di spiaggia-duna (attuali ed abbandonati) e da depositi deltizi (attuali ed abbandonati). il quadro stratigrafico è stato ulteriormente arricchito dai risultati ottenuti dallo studio di 5 perforazioni, che hanno raggiunto profondità variabili da 30 m a 120 m. in particolare, la presenza di due importanti superfici di discontinuità ha permesso di distinguere tre unità litostratigrafiche sepolte, di cui sono stati delineati i principali elementi geometrici e sono stati descritti i caratteri di facies. l’unità stratigraficamente più bassa di età pleistocene medio superiore, denominata “substrato” e dello spessore di almeno 76 m, è risultata costituita prevalentemente da depositi siltoso-argillosi riferibili ad ambienti variabili dalla piattaforma al marino poco profondo. in base ai dati stratigrafici ottenuti, le porzioni più grossolane del substrato mostrano lo stesso significato genetico-deposizionale delle unità affioranti rappresentate dai “depositi sabbioso-conglomeratici dei prismi costieri regressivi”, mentre le parti più fini sono correlabili alla formazione nota regionalmente con il nome di argille subappennine. la presenza sul substrato di una netta superficie di erosione, rinvenuta nel sondaggio cs alla profondità di 44 m, permette di identificare una seconda unità litostratigrafica denominata informalmente “depositi della piana sepolta di metaponto”. questa unità è costituita da depositi sabbioso-ghiaiosi non più spessi di 7 m e mostranti associazioni di facies variabili dal continentale al marino poco profondo. l’età di tale unità è riferita al pleistocene superiore. infine sia sui “depositi della piana sepolta di metaponto” che sul “substrato” si rinvengono i “depo321stratigrafia dei depositi pleistocenico-olocenici dell’area costiera ... siti della piana di metaponto” costituenti un cuneo sabbioso-ghiaioso che si chiude verso terra passando da circa 48 m a 0 m. i “depositi della piana di metaponto” (parzialmente affioranti) sono costituiti da sabbie e sabbie ghiaiose, che nell’insieme individuano un sistema di spiaggia progradante, lateralmente associato ad un sistema deltizio che passa distalmente ad un sistema di piattaforma. la datazione radiometrica di un guscio di bivalve prelevato alla profondità di 35 m, e che ha restituito un’età non calibrata di 7.562±50 bp, permette di attribuire i “depositi della piana di metaponto” all’olocene. ringraziamenti gli autori desiderano ringraziare i proff. bellotti dell’università di roma la sapienza, longhitano dell’università della basilicata e tropeano dell’università di bari per gli utili suggerimenti e per la lettura critica del manoscritto. un ringraziammento va al sig. piccenna del consorzio di bonifica di bradano e metaponto per aver cortesemente fornito materiale cartografico e al dott. mallardo dell’anas della basilicata per aver messo a disposizione alcuni dati di profondità. il lavoro è stato eseguito e pubblicato con fondi miur (cofin 2003, responsabile nazionale tullio pescatore), e con fondi di ateneo dell’università di bari (ex 60% 2005-2009, responsabile luisa sabato). bibliografia amato a. 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(1922 ) a scale of grade and class terms for clastic sediments. journal geology, 30, 377-392. 323 ms. ricevuto il 18 febbraio 2009 testo definitivo ricevuto il 18 luglio 2009 ms. received: february 18, 2009 final text received: july 18, 2009 stratigrafia dei depositi pleistocenico-olocenici dell’area costiera ... base genesi e significato del riempimento della depressione carsica di piano locce sul gran sasso d’italia (abruzzo) donatello magaldi1a/1b, alessandro lorè 2, paolo lorenzoni 3, roberto sulpizio 4, giovanni zanchetta 5, giuseppina benedetti 6 & fabiola ferrante 6 1adisat, facoltà d’ingegneria dell’università di l’aquila 1bdssnp, facoltà di agraria, università di firenze, e-mail: donatello.magaldi@unifi.it 2libero professionista, collaboratore di ricerca al disat, l’aquila 3cra-apc, unità di ricerca per i sistemi agro-pastorali dell’appennino centrale, rieti 4cirisivu, facoltà di scienze matematiche, fisiche, naturali dell’università di bari 5dst, facoltà di scienze matematiche, fisiche, naturali dell’università di pisa 6diccm, facoltà d’ingegneria dell’università di l’aquila riassunto: magaldi d. et al., genesi e significato del riempimento della depressione carsica di piano locce sul gran sasso d‘italia (abruzzo). (it issn 0394-3356, 2009). in una depressione carsica della catena del gran sasso (piano locce), nei pressi di s. stefano di sessanio in provincia di l’aquila, è stato effettuato un sondaggio profondo fino a 90 m circa, che ha permesso di campionare una alternanza di materiali finemente stratificati propri d’ambiente palustre e pedogenetico, costituiti questi ultimi quasi esclusivamente da piroclastiti a granulometria variabile tra media e moderatamente fine che riempiono questa ed altre valli carsiche dei dintorni. sui campioni sono state eseguite analisi chimico-fisiche di routine, micromorfologiche al microscopio da petrografia, microchimiche tramite spettrometria sem-eds e infine analisi chimiche totali per spettrometria ad emissione di raggi x. sulla base dei risultati analitici,si è suddiviso il riempimento in tre gruppi (α, β‚ γ). il gruppo αα rappresenta materiali sedimentari non pedogenizzati di ambiente palustre; il gruppo ββ materiali variamente pedogenizzati identificabili forse con gli udifluvents della soil taxonomy (soil survey staff, usda 1999), mentre il gruppo γγ‚ rappresenterebbe, sia sedimenti palustri, che tufiti pedogenizzate con suoli decisamente idromorfi, quali gli hydraquents suoli. in questi ultimi due gruppi, l’azione pedogenetica prendeva il sopravvento sulla sedimentazione, dando origine a microstrutture otticamente anisotrope e ad una certa orientazione dei domini argillosi. le analisi al microscopio elettronico condotte sui campioni più ricchi di minerali vulcanici, hanno evidenziato come il vetro vulcanico della stragrande maggioranza dei livelli sia completamente alterato e quindi inutilizzabile per la classificazione chimico-petrografica dei livelli stessi. due soli campioni provenienti dalla base (78-80 m) e dal tetto (5 m) della carota si presentavano meno alterati degli altri e sono stati classificati come una latite-trachite e una foidite, rispettivamente. il campione con composizione latitico-trachitica potrebbe essere tentativamente attribuita alle eruzioni pleistoceniche del vulcano di vico, caratterizzate da attività esplosiva di composizione trachitico-fonolitica (peccerillo, 2005), datate intorno a 170.000 anni fa. il campione di composizione foiditica, anche basandosi sull'associazione delle fasi mineralogiche dominate da leucite e clinopirosseno (assente il plagioclasio), può essere correlata con l'attività del vulcano dei colli albani, e più precisamente con l'eruzione dei peperini, le cui ultime fasi sono datate a circa 36.000 anni (freda et al., 2005). gli altri campioni analizzati sono risultati troppo alterati per essere utilizzabili, ma i dati sulle associazioni mineralogiche e di microanalisi delle fasi minerali indicano per la maggioranza di essi una stretta affinità con la composizione delle eruzioni dei vulcani campani (peccerillo, 2005). due soli campioni, sulla base della microanalisi dei pirosseni e dei plagioclasi e della paragenesi mineralogica, possono essere invece correlati con l’attività dei vulcani laziali (peccerillo, 2005). successivamente è stato preso in considerazione il rapporto limo/argilla in funzione della profondità, peraltro con andamento approssimativamente inverso a quello della percentuale di sostanza organica, come un possibile indice paleo-climatico, dove i valori più bassi indicherebbero periodi più favorevoli alla pedogenesi e alla diffusione della vegetazione (e quindi più caldi e più umidi), al contrario dei valori più alti che potrebbero testimoniare periodi più freddi e probabilmente più aridi. tutti i risultati testimoniano chiaramente che la valle carsica di piano locce (una vera e propria polje) è stata interessata in vari momenti del quaternario antico da una sequenza di eventi sedimentari (palustri-lacustri ) e pedogenetici, che si sono impostati su materiali piroclastici provenienti dalle eruzioni della provincia comagmatica romana e continuate fino ai giorni nostri a partire da tempi più antichi di 200 mila anni circa. le caratteristiche pedogenetiche osservate in sezione sottile insieme all’andamento del rapporto limo/argilla suggeriscono variazioni climatiche a diverso regime di umidità in ambiente di alta montagna. quando le condizioni climatico-vegetazionali consentirono l’instaurarsi di processi pedogenetici, si formarono suoli poco evoluti, fortemente condizionati da idromorfia. apporti colluviali e/o eolici da suoli maggiormente evoluti e di ambiente climatico molto differente (“terre rosse” tipo xeralfs o ustalfs) presenti sui rilievi carbonatici circostanti hanno contribuito, sia pure in minima parte, al riempimento della depressione. abstract: magaldi d. et al., the filling of karstic depression of piano locce (gran sasso range, abruzzi, italy) genesis and significance. (it issn 0394-3356, 2009). a deep test hole down to 90 m was carried out on the clastic filling of a karstic valley (polje) of the gran sasso (piano locce) range near s.stefano di sessanio (l’aquila province, italy ). this allowed us to sample alternated lacustrine and pedogenetic materials almost exclusively formed on medium-fine textured pyroclastic deposits. on almost one hundred samples some routine chemical-physical, optical micro morphologic, sem –eds microchemical determination and spectrometric by x ray emission analysis were performed. after the results elaboration, the collected samples were grouped (α, β‚ γ) as follows: α group was related to not pedogenetic sedimentary material (lake and or marsh); β group was identified as soil or soil derived material perhaps to be classified as udifluvent according to usda soil taxonomy; γ group was considered a mixture of the previous groups, except soils, which were classified as hydraquents. the pedogenetic process was prevailing on the ripening, so originating anisotropic microstructures with some orientation of clay domains in thin sections of undisturbed samples. the sem analysis indicated that most of volcanic glass was completely weathered: only the less weathered sample of the core bottom (78-80 m) was classified as related to latite-trachyte rock. il quaternario italian journal of quaternary sciences 22(2), 2009 171-188 172 d. magaldi et al. 1. introduzione alcuni anni fa (magaldi et al., 2006), furono eseguiti nei depositi di riempimento di due depressioni carsiche della catena del gran sasso d’italia due sondaggi profondi, in località piano locce e piano lucchiano, in comune di s. stefano di sessanio (l’aquila), rispettivamente 80 e 50 metri (fig.1). il piano locce ed il piano lucchiano sono depressioni tettono-carsiche che si aprono sul versante meridionale del massiccio del gran sasso d’italia. la loro origine è da ricondursi a fasi tettoniche, in regime distensivo e transtensivo, succedutesi a partire dal pleistocene inferiore, che hanno resecato una superficie a bassa energia di rilievo probabilmente pliocenica (superficie di anzano) secondo bertini et al., (1989), conferendo all’area una situazione strutturale del tipo horst e graben. il substrato è formato in prevalenza da unità carbonatiche mesozoiche, in facies di margine di piattaforma carbonatica e di transizione piattaforma-bacino (gradino ribassato, rampa carbonatica, scarpata), costituite essenzialmente da calcari bioclastici, calcareniti e calciruditi, in strati da medi a spessi, a luoghi con intercalazioni micritiche (apat, 2006). a queste seguono, in discordanza angolare, calcareniti e calciruditi cenozoiche in facies di rampa – piattaforma aperta. i depositi di riempimento delle depressioni sono costituiti da sedimenti di ambiente limno-palustre, con limitati apporti fluvio-torrentizi dai vicini e ripidi versanti; diffuse sono le coltri detritiche, a granulometria variabile, da grossolana (falde di detrito) a fine (coltri colluviali). i risultati di una prima serie di indagini condotta sulle due sequenze è stata descritta in una nota preliminare divulgativa alla quale si rimanda (magaldi et al., 2006). in questa sede basterà ricordare che le osservazioni di campagna e alcune analisi fisiche (granulometria e colore) e chimiche (% di sostanza organica sul setacciato a 2 mm e % di “ferro libero”), su una decina di campioni interpretati in campagna come tufiti pedogenizzate, sedimenti lacustri e/o sedimenti di suolo (tab.1 e tab.2), indicano che i due riempimenti sono costituiti da clasti di grandezza medio-fine, con caratteristiche a volte tipicamente lacustri, a volte tufitiche, queste ultime spesso intensamente pedogenizzate, e che esiste una relazione abbastanza evidente tra l’andamento del rapporto limo/argilla e il contenuto in sostanza organica (indicativo di processi pedogenetici avvenuti o in atto). il rapporto fe ossalato / fe ditionito (che scaturisce dall’analisi del “ferro libero”) è alto per quasi tutti i campioni, ad indicare che i processi pedogenetici sono stati poco evoluti. la nota ricordata suggeriva che alla genesi dei due riempimenti, avvenuta prevalentemente in ambiente riducente palustre, vista la frequenza di vivianite autisuch a composition could be related with the vico pleistocene eruption, which is constituted by trachite-phonolitic lavas ((peccerillo, 2005). consequently, this sample could be correlated to the pyroclastic deposit of the adriatic sea collected from a core 170,000 years before the present date (calanchi et al., 2008). taking into consideration the low contents of na2o and clo , a correction (3 – 4 %) was made for the sum of alkaline oxides in order to classify the glass as a tephritic-phonolite and phonolite lavas which are assumed to be erupted by the campania volcanism (peccerillo, 2005). based on the composition of both pyroxene and plagioclase minerals and the paragenesis, 2 samples were attributed to the latium volcanism. it was also considered that the silt/clay ratio vs. the core depth, which demonstrated an inverse trend with the percentage of organic matter, could be assumed as a paleo-climatic index. low values of the index could indicate more favourable conditions for pedogenesis unlike higher values which could indicate colder and perhaps more arid periods. in conclusion, all results likely indicate that the piano locce depression during quaternary age was subjected to various sedimentary and pedogenetic phases which occurred on pyroclastic deposits coming from the co-magmatic roman province, starting from the present age to more than 200,000 years ago. climatic variations in a high mountain environment are suggested by trends of both organic matter and silt/ clay ratio as well as micromorphological features, which in very few cases show periglacial aspects. some scarcely developed hydromorphic soils only formed when the favourable climatic conditions occurred. a very limited colluvial and/ or eolian material from more developed soils of different climatic environments (red soils such as xeralfs or ustalfs) together with some occasional deposition of creeks from surrounding carbonate slopes contributed filling the piano locce and nearby karst valleys. parole chiave: paesaggio carsico, provincia comagmatica romana, micromorfologia del suolo. keywords: karst landscape; co-magmatic roman province; soil micromorphology. fig. 1 localizzazione della zona dove è stato effettuato il sondaggio. location of study area where borehole was carried out. 173genesi e significato del riempimento della depressione carsica ... gena (fosfato di ferro idrato) avessero partecipato, sia materiali provenienti dall’erosione dei versanti, sia piroclastiti dai vulcani esterni all’area abruzzese e forse interni, a causa della comune presenza di sanidino e augite, a volte visibili anche ad occhio nudo. per di più, dall’analisi degli andamenti della % di sostanza organica, risultava che i due riempimenti sono tra di loro confrontabili, pur essendo sfasati stratigraficamente di una decina di metri. pertanto la nuova ricerca è stata focalizzata sul riempimento più potente di piano locce, litologicamente simile a quello di piano lucchiano, distante poco più di quattro chilometri in linea d’aria, sempre in comune di s.stefano di sessanio. 2. inquadramento geologico-geomorfologico di piano locce il piano locce, situato a una quota compresa tra 1225 e 1240 m s.l.m., ha una forma grossolanamente pentagonale con diametro medio di circa 1,1 chilometri. il settore centro-meridionale appare sostanzialmente pianeggiante, mentre il settore nord-orientale è occupato da un’ampia conoide di deiezione afferente ad un primitivo reticolo di valli, almeno in parte di origine fluviale, attualmente inattivo (fig. 2). la depressione è endoreica; lo smaltimento delle acque superficiali è assicurato da un inghiottitoio ubicato lungo il margine occidentale, in corrispondenza di una faglia distensiva che ha come espressione una ben evidente scarpata morfologica. la depressione è attualmente occupata da un laghetto, probabile residuo di una forma a maggior sviluppo nel passato, modificata successivamente dagli interventi antropici degli ultimi secoli. l’attuale profondità sabbia limo argilla tessitura (m) (%) (%) (%) 0,0 29,6 49,6 20,8 f 2,8 21,7 57,7 20,6 fl 3,1 16,2 55,5 28,3 fla 4,5 59,4 34,1 6,5 fs 6,2 49,8 28,4 21,8 fsa 8,4 59,6 32,8 7,6 fs 9,0 27,0 68,3 4,7 fl 9,4 20,2 50,7 29,1 fla 9,7 32,1 50,5 17,4 fl 10,9 54,2 41,8 4,0 fs 11,7 21,7 57,3 21,0 fl 13,0 27,9 55,0 17,1 fl 13,8 56,8 28,0 15,1 fs 14,0 26,4 33,6 40,0 fa 14,6 16,7 60,4 22,9 fl 16,0 23,3 53,6 23,1 fl 16,7 16,1 62,3 21,6 fl 18,4 8,1 85,2 6,7 l 21,4 41,3 45,3 13,4 f 22,0 45,1 37,8 17,1 f 23,0 26,5 50,1 23,5 fl 23,5 21,7 69,1 9,1 fl 24,0 11,8 68,7 19,5 fl 25,5 5,3 55,2 39,4 fla 26,4 7,9 59,6 32,4 fla 27,0 53,8 35,7 10,5 fs 27,4 14,5 58,7 26,8 fla 28,6 8,9 41,1 50,1 al 30,0 46,0 47,3 6,7 fs 30,6 23,5 69,3 7,1 fl 21,2 31,3 36,4 32,3 fa 31,8 59,8 29,4 10,8 fs 32,2 33,5 59,2 7,3 fl 33,0 34,5 57,9 7,6 fl 33,9 25,2 70,1 4,7 fl 35,1 57,8 31,5 10,7 fs 36,0 12,8 80,9 6,3 l 36,4 32,9 59,3 7,8 fl 37,3 29,4 62,9 7,7 fl 38,7 40,2 53,5 6,2 fl 40,0 18,1 59,9 22,0 fl 40,4 4,8 68,5 26,7 fla 42,1 4,3 87,0 8,7 l 42,7 42,4 53,3 4,3 fl 43,3 50,8 47,3 1,9 fs 44,0 61,0 37,4 1,6 fs 44,5 69,0 29,6 1,5 fs 46,0 23,1 69,3 7,6 fl 46,5 54,0 43,8 2,2 fs 49,6 64,8 33,0 2,2 fs 52,2 63,4 32,7 3,9 fs 54,0 42,7 52,0 5,3 fl 56,8 16,5 76,7 6,8 fl 57,4 49,9 44,7 5,4 fs 58,0 25,1 56,4 18,5 fl 58,7 16,7 75,7 7,6 fl 60,3 12,5 52,4 35,1 fla 61,0 23,6 47,1 29,3 fa 65,1 13,8 58,9 27,3 fl 65,2 17,4 67,1 15,5 fl 67,5 13,9 77,2 8,9 fl 71,0 23,7 70,4 5,8 fl 72,0 35,7 53,5 10,8 fl 73,0 31,7 57,0 11,3 fl 74,4 57,8 36,8 5,4 fs 75,3 36,8 55,6 7,6 fl 76,1 26,5 64,7 8,8 fl 78,0 14,2 75,8 10,0 fl 90,0 37,8 57,8 4,4 fl tab. 1 analisi tessiturali dei livelli campionati entro il riempimento della conca di piano locce. textural analysis of samples. tab. 2 rapporto fe ossalato/ fe ditionito e contenuto in fe libero in alcuni campioni con caratteristiche pedologiche visibili ad occhio. fe oss/ fe dit ratio and free (extractable) iron content for some samples of piano locce and piano lucchiano, that by field observation, were assumed to be soils or soil sediments. piano locce campione profondità fedi feos feos/fedi fe libero (m) (%) (%) (%) pl10 12,0 0,11 2,91 26,5 3,02 pl11 13,0 0,11 2,30 20,9 2,41 pl13 14,0 0,18 2,88 16,0 3,06 pl14 14,6 0,17 0,62 3,6 0,79 pl15 16,0 0,11 1,61 14,6 1,72 pl19 21,4 0,17 0,98 5,8 1,15 pl47 30,0 0,17 0,63 3,7 0,80 pl48 31,0 0,16 0,78 4,9 0,94 pl78 60,3 0,19 0,65 3,4 0,84 piano lucchiano campione profondità fedi feos feos/fed fe libero (m) (%) (%) (%) lu05 46,6 0,20 1,56 7,8 1,76 lu14 36,3 0,01 2,94 294,0 2,95 lu25 16,7 0,02 0,86 43,0 0,88 lu30 11,5 0,02 1,63 81,5 1,65 lu31 10,5 0,04 2,54 63,5 2,58 lu32 9,3 0,03 1,66 55,3 1,69 lu34 5,1 0,04 2,83 70,8 2,87 lu35 4,5 0,04 2,25 56,3 2,29 174 copertura pedologica consiste in un suolo franco sabbioso argilloso, di colore umido bruno molto scuro (10 yr2/2) che sostiene una vegetazione prativa spontanea, a luoghi coperto da ciottoli calcarei di diametro compreso tra 2 e 10 cm, passante dopo circa 2-3 m di profondità ad un livello ghiaioso di origine alluvionale, con matrice di colore umido bruno giallastro scuro (10 yr3/4). questo suolo a profilo a/c si è formato prevalentemente su materiali colluviali provenienti dai versanti circostanti, contiene pochi minerali vulcanici (sanidino, clino-pirosseno verde leggermente pleocroico e apatite) non arrotondati, ed è classificabile come hydraquent, a causa delle sue condizioni aquic (risultanti principalmente dal colore umido) per la maggior parte degli anni (usda soil survey staff, 1999). 3. caratteristiche generali del riempimento di piano locce e metodi d’indagine come è già stato detto, il riempimento è costituito da una alternanza di materiali finemente stratificati propri d’ambiente lacustre e di piroclastiti a granulometria (sul setacciato a 2 mm) variabile tra media e fine. alcuni livelli più superficiali sono formati da clasti calcarei grossolani poco smussati e appiattiti, mentre altri sono stati classificati in campagna come suoli e sedimenti di suolo con caratteri di idromorfia. sulla base del colore munsell opportunamente codificato (vedi didascalia fig. 3) sono stati distinti in via preliminare due gruppi di sedimenti, il primo tra 0 e 30 m, il secondo da 30 fino alla massima profondità raggiunta (80 m). ad eccezione dei livelli situati rispettivamente a 4,5 e 9 m di profondità, la parte superiore è rappresentata da materiali misti d’ambiente generalmente ossidante (colori umidi principalmente con hue compreso tra 10yr e 2.5y, codificati con i numeri 10 e 20) mentre quella inferiore da matefig. 2 schema geologico-morfologico del piano locce in provincia di l’aquila. 1 unità calcaree mesozoiche, 2 brecce calcaree in matrice rossastra (formazione di fonte vedice auct., sintema di aielli-pescina), 3 detriti di falda, coltri colluviali (sintema di valle majelama), 4 sedimenti fluvio-lacustri, 5 scarpata di faglia, 6 . orlo di polje, 7 conoide di deiezione inattiva, 8 – inghiottitoio, 9 stagno (parzialmente modificato per azione antropica), 10 ubicazione sondaggio. geological and geomorphologic draft of the piano locce area (l’aquila province). 1 mesozoic calcareous units, 2 calcareous breccia with red matrix (formazione di fonte vedice auct., sintema di aielli-pescina), 3 scree slope and colluvial deposit (sintema di valle maielama), 4 river –palustrine sediments, 5 fault scarp, 6 polje edge, 7 inactive alluvial fan, 8 swallow hole, 9 marsh partly modified by human action, 10 borehole location. d. magaldi et al. 175 riali depositati in ambienti quasi esclusivamente riducenti (colori con hue compreso tra 2.5 y e 5y, codificati con i numeri 20 e 40). nel primo gruppo il rapporto limo/argilla tende ad essere mediamente più basso che nel secondo, mentre il contrario accade per la sostanza organica che tende a diminuire con la profondità. per il resto, i due gruppi sono pressoché simili. e’ stato quindi necessario sottoporre i campioni ad una serie di analisi più specialistiche e dettagliate, quali l’analisi micromorfologica in sezione sottile (bullock et al., 1985; stoops, 2003) e quella chimica totale tramite xrf presso la facoltà di ingegneria della università di l’aquila. la prima consiste nell’osservazione al microscopio ottico a luce polarizzata di sezioni sottili petrografiche, ottenute da campioni indisturbati di sedimento opportunamente indurito con resine sintetiche, mentre la seconda utilizza “pasticche” di sedimento compresso e quindi analizzato con uno spettrometro ad emissione di raggi x, mod. spectroxepos. sui livelli più ricchi in vetro e minerali vulcanici sono state eseguite microanalisi tramite spettrometria sem-eds presso il dipartimento di scienze della terra dell’università di pisa. 4. risultati delle analisi micromorfologiche e chimiche 4.1. analisi micromorfologiche lo studio al microscopio polarizzatore è stato eseguito sulla base di considerazioni derivanti dalla petrografia sedimentaria applicata (bertrand, 1969; selby, 1993; tickel, 1965) e di micromorfologia del suolo e del regolite (brewer, 1964; bullock et al., 1985; stoops, 2003). sono state perciò descritte, per ciascun campione e nell’ordine, le seguenti caratteristiche: • tipologia della microstruttura (stoops, 2003); • relazioni tra matrice (pasta di fondo, cemento) e costituenti grossolani > di 20 microns; • natura dei costituenti minerali e organici (coarse mineral grains and rock fragments; organic components; elements figurés), distinti in clastici e di neoformazione in situ; • figure (features) di origine pedogenetica, sia formate in situ che trasportate dall’esterno; • tipologia della matrice (fine groundmass type and bfabric). tutti i campioni sono risultati “fango sostenuti” (matrix supported) o porfiroschelic secondo la dizione micromorfologica e pertanto questo carattere non è stato preso in considerazione al fine della loro differenziazione. al contrario si sono notate evidenze di alcune microstrutture presumibilmente di origine pedogenetica, in diversi campioni, la maggior parte dei quali, tuttavia, è caratterizzata da una microstruttura massiva (matrix microstructure , secondo g r a b o w s k a olszewaska et al., 1984, in selby, 1993) o più di rado, finemente laminata, di origine prettamente sedimentaria. la pasta di fondo è quasi esclusivamente costituita da vetro vulcanico variamente alterato, spesso con formazione di idrossidi di ferro e minerali argillosi sia amorfi che cristallini. il campione che ne contiene di più (oltre il 90%) è pl 82 a 67-68 m di profondità, dove il vetro appare quasi completamente isotropo. si possono distinguere al microscopio due tipi di vetro: uno marrone-giallastro con bolle e indice di rifrazione superiore alla resina del vetrino (1,54) e un altro grigio e grigio scuro con indice inferiore alla resina e, a volte, con inclusi microliti di feldspato. i costituenti grossolani (coarse) sono stati distinti in due gruppi: gli inorganici (rocce e minerali ) e gli organici. quest’ultimi, abbastanza rari, sono riconoscibili come frammenti carbonizzati, frustoli legnosi e residui vegetali non identificati. tra i litorelitti prevalgono i frammenti di vulcaniti, sia basiche che acide e, molto subordinatamente, le selci e le arenarie quarzitiche. i costituenti minerali grossolani sono stati a loro volta distinti sulla base della presunta provenienza: vi sono infatti minerali quali muscovite, epidoto, clinozoisite, clorite, calcite, quarzo, tormalina, cloritoide, zircone, granato (incolore), anatasio e glauconite, che derivano probabilmente dal residuo insolubile dei litotipi calcarei e dolomitici della zona e/o da suoli e sedimenti vari formatisi a carico delle formazioni flyschioidi situate nel versante adriatico (ad esempio, arenaria della laga). questi costituenti sono in quantità nettamente trascurabile rispetto al gruppo di minerali di chiara provenienza vulcanoclastica: sanidino, biotite, clinopirosseni, plagioclasi, anortoclasio, e più raramente, magnetite, granato (gialloscuro), orneblenda bruna, palagonite, titanite, leucite ed haüyna,quasi tutti abbastanza freschi ma, a volte, con orlo di riassorbimento magmatico. vi sono due tipi principali di clinopirosseno: il primo è incolore, biassico positivo, con c: γ = 35°-40°, il secondo, sempre biassico positivo, è leggermente verde e pleocroico con c: γ = 40°-45°. in prima approssimazione si ritiene che il primo possa essere un termine diopsidico, mentre il secondo un termine augitico, forse titanifero. l’anortoclasio è stato riconosciuto solo in alcuni campioni sulla base della caratteristica geminazione a tratteggio incrociato (cross–hatch) e dal 2v nettamente superiore a quello del sanifig. 3 relazioni tra il colore munsell e il rapporto limo/argilla dei vari campioni. il colore è codificato secondo lo schema seguente: 7.5yr=7,5; 10yr=10; 2.5y=20; 5y=40. munsell soil color vs. silt/ clay ratio for all samples. the colour code is the following: 7.5yr=7,5; 10yr=10; 2.5y=20; 5y=40. genesi e significato del riempimento della depressione carsica ... 176 dino, minerale presente e frequente in tutti i campioni. rari i feldspatoidi (leucite) e sempre molto alterati. minerali di neoformazione (pedogenetica e/o diagenetica) nel sedimento sono la vivianite (fosfato di fe idrato ), la siderite (carbonato di fe) e la calcite spatica. molto rara, e riconosciuta solo in due campioni, la gibbsite (idrossido di al). la vivianite, tipica di sedimenti e suoli di ambienti riducenti, si presenta sotto forma di aggregati nodulari e raggiati anche millimetrici e centimetrici, con il tipico colore bianco che diviene poi celeste chiaro per ossidazione, ben visibile anche ad occhio nudo. secondo retallack (2001) potrebbe formarsi anche per sostituzione del carapace degli artropodi. west (1968) elenca la vivianite fra i minerali riscontrati nei depositi pleistocenici. altri (www.mindat.org) affermano che la vivianite sostituisce materiali organici, torba, ferro delle paludi ecc. o quanto meno è strettamente associata con questi materiali nei depositi alluvionali recenti. la siderite si presenta in varie forme. compaiono, infatti, i festoni e le forme nodulari a raggiera (sferosiderite) che sono generalmente associate alla vivianite, indicando così ambienti di formazione moderatamente riducenti. la gibbsite è stata riscontrata come alone intorno a un granulo di clorite e la sua presenza potrebbe essere legata alla trasformazione di materiali allofanici derivati dalla alterazione del vetro vulcanico (buol et al., 1980; bullock et al.,1985). numerose come tipologia sono le figure (features) di origine pedogenetica, per la maggior parte provenienti per erosione dai suoli circostanti l’ambiente di sedimentazione del deposito, e solo in parte più limitata, derivanti da processi pedogenetici agenti sul deposito in condizioni di idromorfia, presumibilmente tipo “surface water gley” (driessen & dudal, 1991). qui di seguito sono descritte le varie figure. noduli. sono costituiti per la maggior parte da singoli individui rotondeggianti e da aggregati a forma irregolare, di idrossidi di ferro/manganese, sia formatisi in situ (orthic nodules) sia trasportati dall’esterno (anorthic nodules). abbondanti sono anche gli aggregati di materiale pedogenizzato (matrix anorthic nodules) che testimoniano la provenienza da suoli presenti probabilmente sui fianchi del bacino. secondo la classificazione micromorfologica più recente sarebbero comprese tra i noduli anche le papule (brewer, 1964), più modernamente classificate come clay nodules. sono frammenti di argilla finemente cristallina iso-orientata che testimoniano la presenza di suoli ad orizzonte illuviale, probabilmente le “terre rosse” da calcare, osservabili ancora nella conca aquilana (magaldi & tallini, 2000). nella descrizione delle sezioni si è tuttavia preferito separarle dagli altri noduli in considerazione del loro importante significato genetico. infilling. traducibili in italiano come “riempimenti”, sono cavità riempite da materiale pedogenetico vario, per cause prevalentemente biologiche. in questo deposito sono stati classificati come tali alcuni corpi a contorno netto , costituiti da accumulo regolare di argille iso-orientate entro cavità rotondeggianti. clay coatings. in tre campioni (pl20, pl21, pl46) sono stati riconosciuti rivestimenti di argilla di colore (a nicols //) giallo-bruno, a volte a tessitura limoso-fine, che si sono sicuramente formati in situ, in seguito a processi pedogenetici di mobilizzazione e trasloco di argilla di neogenesi o ereditata, tipici degli alfisols e degli ultisols (soil taxonomy, usda, 1999). fabric of micromass. in accordo con stoops (2003), la fabric della micro-massa del suolo o b-fabric (parte fine della groundmass che costituisce il materiale di base del suolo ad esclusione delle figure pedologiche) riflette i processi pedogenetici attuali e del passato che hanno agito sul suolo e, per di più, le caratteristiche litologiche e di alterazione del parent material. la maggior parte si presenta con una undifferentiated fabric (indifferenziata) e unistrial (laminare), tipologie che testimoniano condizioni tipicamente sedimentarie piuttosto che pedogenetiche. al contrario i depositi che sono stati soggetti a condizioni ossidanti, anche temporanee e periodiche, si presentano spesso con domini argillosi orientati e anisotropi, in genere disposti lungo le pareti delle fessure e intorno ai granuli, a causa della contrazione e del rigonfiamento dei materiali argillosi (stress cutans, secondo brewer, 1964) che originano una striated fabric. sono state riconosciute le seguenti cinque b-fabric: undifferentiated – potrebbe corrispondere in sedimentologia alla struttura massiva e isotropa. crystallitic – caratterizzata dalla precipitazione tra i granuli più grossolani di un cemento, in questo caso calcitico, dovuto probabilmente a momenti di maggiore aridità del clima. speckled domini argillosi anisotropi piccoli e orientati casualmente: in questo caso rappresenta un inizio di argillificazione del deposito. striated – domini argillosi anisotropi in strisce o zone allungate, costituiti da argille orientate: in questo caso si tratta di un orientamento dovuto a contrazione e rigonfiamento periodico delle argille. strial – e’ costituita da una (unistrial) o due (bistrial) orientazioni delle argille secondo micro-lamine tra loro parallele, generalmente di origine sedimentaria. i risultati delle indagini sulle sezioni sottili sono espressi nella tab. 3 insieme ai valori della sostanza organica e del rapporto limo/argilla. le caratteristiche micromorfologiche sono codificate secondo quanto si evince dalla legenda della tab. 4, mentre le numerose foto ottenute con macchina fotografica canon power shot s50 digitale montata su microscopio polarizzatore nikon optiphot2-pol con oculare 10 x e obiettivi di 4, 10 e 20 x, sono presentate a colori, secondo un raggruppamento ragionato, nell’allegato cd e organizzate come segue: • composizione mineralogica e litologica originaria delle piroclastiti: frammenti di rocce sedimentarie e vulcaniche, minerali vulcanici e sedimentari: dalla foto 8 alla foto 16 • figure pedogenetiche formatesi in situ o di apporto esterno: dalla foto 17 alla foto 34 • minerali di neoformazione (pedogenetici e/o diagenetici): : dalla foto 35 alla foto 49 • residui vegetali: dalla foto 50 alla foto 55 • microstrutture sedimentarie, periglaciali e resti fossilizzati: dalla foto 56 alla foto 61. dall’esame comparato delle caratteristiche riscontrate nei vari livelli attraversati dal sondaggio emergono alcuni fatti, oltre la già ricordata relazione inversa tra contenuto in sostanza organica e il rapporto limo/argild. magaldi et al. 177 tab. 3 risultati dell’analisi micromorfologica in sezione sottile di 59 campioni rappresentativi del riempimento. qualitative micromorphological analysis of thin sections of 59 undisturbed samples. deepness color silt/ % clastic min. volcan.min. neoform. pedofeatures micromass environment in m codex clay organic & & rocks minerals (ambiente di matter sed. rocks formazione) pl 00 0 10 2,4 32 q,e, h,d,b no,pa, un,uns gruppo gamma pl 01 2,80 7,5 2,8 12 c,s,q b,h nfe,nca,nar msp gruppo gamma pl 02 3,10 20 2,0 13 s h,d, no,pa, nca mos gruppo beta pl 03 4,50 40 5,3 6 c,s,l n,h,p,b,f ca nca,nfe,inf uns,cry gruppo alfa pl 04 6,20 10 1,3 8 s,r, v, h,p, vi pa, pas gruppo gamma pl 05 8,40 10 4,3 4 c,l v,d,h,b,p vi,si,le,gi pa,nar,no msp gruppo gamma pl 06 9,00 40 14,5 11 l v,b,d,h,p, nar un gruppo alfa pl 07 9,40 7,5 1,7 13 c,l,q d,h,y,b,f, vi,si nfe,pa, msp gruppo gamma pl 08 9,70 20 2,9 10 s,q,e, c,b v,d,h,p,n no, nca mos gruppo beta pl 09 10,90 20 10,5 4 c, v,h,d,n, nar,pa,no un gruppo beta pl11 13,00 10 3,2 5 v,p,d,n,h no,inf, mos gruppo gamma pl13 14,00 10 0,8 10 s, v,f,h,n,b vi nfe,pa,inf mos,gr gruppo gamma pl14 14,60 10 2,6 12 s,c,q,r h,v,d, no uns,gs gruppo gamma pl15 16,00 10 2,3 24 s,m g,b,h,d,t si,vi, gi no uns,gs gruppo gamma pl16 16,70 10 2,9 16 c,l d,h,b, vi,si nar,pa cro gruppo gamma pl17 18,40 20 12,7 7 s,m,e v,d,h,b, vi,si, no,pa,nfe,nar un gruppo beta pl18 18,40 10 12,7 17 s v,h,d,b vi, si, no,nar uns gruppo gamma pl19 21,40 10 7,7 21 c,r d,h,o,b vi ccu, nar,nfe mos,msp gruppo gamma pl20 22,00 20 2,2 26 m d,h,t, vi,si, nfe,nor, scu mos gruppo beta pl40 23,00 10 7,6 16 s,m,l v,d,b,h vi, pa, nca,nfe un gruppo gamma pl41 23,50 10 3,5 18 s g,d,b,j,f,y,a collofane ? nfe, un gruppo gamma pl42 24,00 20 1,4 17 s,m, d si un gruppo beta pl43 25, 30 20 3,0 14 v,s,q,w g,d,h,b,f,p si nar,nfe,pa un gruppo beta pl21 25,70 20 3,0 13 s,l g,h,d,k,b vi nar,ccu mos gruppo beta pl 46 29,0 20 4,0 12 s,r,o, d,p,o,b,t,h,a vi nar,ccu,no,inf,pa cro gruppo beta pl47 30,00 10 5,2 11 w g, p,h,b,w,f nfe un gruppo gamma pl 48 31,00 10 9,7 10 s d,h,b,g nar,no,nfe ss gruppo gamma pl49 30,60 20 1,1 10 s v,d,h,f,p,b,o,g si nar,no ss gruppo beta pl51 31,80 20 8,1 7 s,r p,d,n,b,t no,nar,pa un gruppo beta pl52 32,20 40 7,6 8 s,e,m,z v,d,n,h,p,t, ca, nfe,pa,no,scu un gruppo alfa pl54 32,95 20 15 9 a,r d,b,h,g,v nfe,pa,nar un gruppo beta pl55 33,90 20 3 7 s d,b,h,p,f,g,v nfe,pa,nar un gruppo beta pl57 36,00 20 7,6 7 z,o v,h,p,n,d,f,b si nfe un gruppo beta pl58 36,40 20 8,1 9 v,d,b,p,h,f nfe,pa ss gruppo beta pl59 37,30 20 8,6 24 s d,b,h,f,g,v si,go nar,pa,nor?,nfe ss,un gruppo beta pl60 38,70 20 8,6 12 s d,h,b,g nfe, fe-mottles bs,gs,pas gruppo beta pl62 40,00 20 2,6 4 m b,p,d pa,nfe mos gruppo beta pl63 40,40 20 10,1 4 s,l,m, v,d, ca nfe cry,un gruppo beta pl64 42,10 40 12,3 6 o v,n,h,d,x,b,p nca,nfe,pa un gruppo alfa pl65 42,70 40 25,4 8 d,h,b ca? pa,nca cry,un gruppo alfa pl66 43,30 40 24 8 s,l,z j,p,n,h,w,b, ca nca, pa un-cry gruppo alfa pl67 44,00 40 20,3 8 d,h,v ca nca cry gruppo alfa pl68 44,50 20 9,1 7 c,s,q,m,l,e v,d,b,h,n ca pa,nar,nfe un gruppo beta pl71 49,60 20 8,4 15 s,r,q d,h,b pa,nfe,nar ss gruppo beta pl72 52,15 10 8,9 15 s v,g,d,h,b,s,f,t,w si nar,pa,nfe un gruppo gamma pl74 56,80 10 9,8 10 s,l,e,m v,k,h,d,f,b,p, si, nfe, un (fe) gruppo gamma pl76 58,00 10 10 10 c d,h,g un gruppo gamma pl77 58,70 20 1,5 12 e v,h,p,d un gruppo beta pl78 60,30 20 1,6 15 s,r,q,u d,b, vi pa,no,inf uns,gs gruppo beta pl79 61,00 20 2,1 14 m,e,l,r b,p,d,h,k, vi,si nar,inf,nfe,pa,scu uns-pas gruppo beta pl80 65,10 20 4,3 13 s,e,m,q, v,h,d,f si nfe, pa un gruppo beta pl81 65,20 40 8,7 8 s,e,m,q, v, h,d, nfe,nor, un gruppo alfa pl82 67,50 40 12,1 4 l v =90%,b,d,h nfe,nar un gruppo alfa pl84 71,00 20 5,0 7 q,s,r v,h,d,p vi inf,nfe,nor un gruppo beta pl85 72,00 20 5,0 7 q p,d,h, inf,nfe,nor un gruppo beta pl86 73,00 40 6,8 8 l,s x,h,d,b,n,f, nar,pa un gruppo alfa pl88 75,30 10 7,3 7 s,l v,g,s,h,x,b, nfe,pa,nar,inf, msp gruppo gamma pl89 76,10 40 7,6 5 a,q v,d,p,n,h,b,t,x,i nfe un-cry gruppo alfa pl90 78,00-80,00 40 13,2 4 v,d,p,n,h,b,x nfe un-cry gruppo alfa genesi e significato del riempimento della depressione carsica ... la. si nota (fig. 3) che questo rapporto tende a crescere con la crescita del valore convenzionale (v. didascalia della fig. 3) del codice munsell (da un hue “rossastro” ad un hue più grigio-azzurro) assumendo tuttavia valori più dispersi, con la progressiva scomparsa dei colori “ossidati” e la crescita di quelli “ridotti“, suggerendo così la maggior frequenza del limo lacustre nei depositi di ambiente sedimentario, e una minor frequenza rispetto all’argilla in quelli presumibilmente pedogenizzati. insieme al rapporto limo/argilla e applicando l’analisi statistica multivariata (codice statistica) alle figure pedologiche e al colore secondo i codici convenzionali riferiti nella fig 3., si ottiene la distribuzione dei (59) campioni in 3 cluster (α, β‚ γ) espressa nella fig. 4, a livello di distanza euclidea da 7 a 12. questi gruppi sono distinti a livello più alto dal colore munsell e, immediatamente dopo, dal rapporto limo/argilla. analizzando in dettaglio i tre gruppi sulla base delle restanti caratteristiche e della composizione mineralogica, si ottengono le informazioni che seguono. gruppo αα. caratterizzato dal colore 5y (codice 40), dall’assenza di b-fabric tipicamente pedogenetiche, da valori di sostanza organica mediamente eguali al 7%, dalla neoformazione abbastanza diffusa di caco3 sotto forma di noduli, di cristalli intercalari e di matrice carbonatica (crystallitic groundmass), rappresenta probabilmente un ambiente palustre a granulometria sensibilmente limosa, in condizioni di ph neutro o subalcalino che in qualche caso andava anche soggetto a momenti di disseccamento e/o di aridità tali da favorire la precipitazione del carbonato. l’analisi pollinica (presenza di conifere quali, abies, picea, pinus mugus ecc.) di un campione prelevato a 67-68 m indica un clima più freddo di quello attuale. il gruppo tende a prevalere oltre i 30 m di profondità. gruppo ββ. questo gruppo eterogeneo, caratterizzato dal colore 2.5y (codice 20), è costituito sia da sedimenti sia da suoli, 178 tab.4 codici utilizzati per le descrizioni micromorfologiche riferite nella tab.3. meaning of codes used for micromorphological description. codificazione dei caratteri micromorfologici minerali clastici e rocce sedimentarie: minerali di neoformazione: clastic minerals neoformed minerals and sedimentary rocks a others ca carbonate c carbonate gi gibbsite e epidote le lepidocrocite i chloritoide si siderite l chlorite vi vivianite m muscovite o garnet figure pedologiche: micromorphologic features q quartz ccu clay-cutans r sandstone inf infilling s chert nar soil-relicts u tourmaline nca ca-nodules w clinozoisite nfe fe-nodules z zircon nor org-aggregates pa papules scu stress-cutans minerali e rocce vulcanici: volcanic minerals and rocks a others fabric microstrutturale: ground-mass fabric b biotite d sanidine rating f magnetite bs bistrial 1 g magm.rock cro cross-striated 5 h clino-pyroxene cry crystallitic 2 j feldspathoids gs grano-striated 4 k apatite mos mono-striated 4 n anortoclase msp mosaic speckled 3 o garnet pos parallel striated 5 p plagioclase pas poro-striated 4 t titanite ss stipple speckled 2 v glass un undifferentiated 0 x hornblende uns unistrial 1 y spinel fig. 4 raggruppamenti (cluster) ottenuti attraverso l’analisi discriminante (codice statistica) considerando come variabili le caratteristiche micromorfologiche. si evidenziano chiaramente a livello 7 -12 tre gruppi principali di campioni. clusters derived from discriminating analysis (statistica software) using some micromorphological features. there are at 7-12 level 3 main samples groups. d. magaldi et al. 179 fig. 5 stratigrafia semplificata del deposito di riempimento della conca. simplified stratigraphy of deposit. tutti formatisi in condizioni comunemente riducenti, testimoniate dalla frequenza della vivianite e della siderite, minerali che compaiono soli o associati. sono sempre ricchi di sostanza organica (in media 11%) e evidenziano apporti, oltre che da piroclastiti, anche da suoli relativamente più evoluti (“terre rosse“ ?) delle immediate vicinanze. nei campioni pl 21 (25,70 m ) e pl 46 (29 m ) si osservano invece resti di pellicole di argilla illuviata (clay coatings) che testimoniano la formazione in situ di suoli maggiormente evoluti (aqualfs oppure boralfs?) , associati a micro-strutture presumibilmente crioturbate (involutions) (vedi cd) che suggerirebbero un clima sensibilmente più freddo dell’attuale. l’interpretazione di queste figure è basata sulla stretta somiglianza che queste presentano con quelle macroscopiche osservabili nei suoli di ambiente periglaciale come i cryorthents e diverse da quelle ricordate per sismiti in depositi pliocenici lacustri da brustur & jipa (2007).anche l’analisi pollinica , sfortunatamente ancora in corso, ha evidenziato nella successione del riempimento momenti più freddi a 3 m e a 44-45 m di profondità. gruppo γγ. caratterizzato da colori più giallo-rossastri, sia della matrice, sia delle screziature (rispettivamente 10yr e 7.5yr, codice 10), da contenuti molto alti (media 13 %) in sostanza organica, ma non uniformemente distribuiti nella sequenza, da b-fabric anisotropiche comunemente attribuite alla pedogenesi, ma in condizioni prevalentemente riducenti, come dimostrato dalla presenza di vivianite e siderite. si tratta presumibilmente di suoli idromorfi torbosi poco evoluti (come rivelato dal rapporto fe-ossalato/fe-ditionito su alcuni campioni presi a caso, tab. 2). la colonna stratigrafica, ipotizzata sulla base delle precedenti considerazioni, è mostrata in fig. 5. le analisi petrografiche e micromorfologiche confermano gran parte delle osservazioni fatte in campagna all’atto del sondaggio e mettono in evidenza che il riempimento della valle carsica è costituito sia da sedimenti ricchi di materiali vulcanici in un ambiente prevalentemente palustre-lacustre riducente (abbondanza di sostanza organica e probabile neoformazione di vivianite e siderite) entro il quale si depositavano anche sedimenti di suoli relativamente più evoluti e forse materiali eolici dalla regione adriatica (arenarie della laga, e forse addirittura dal nord africa secondo quanto ipotizzato da yaalon, 1987), sia da veri e propri suoli tipicamente idromorfi, a diverso grado di evoluzione, di cui si conservano indiscutibili tracce. sulla base delle precedenti osservazioni è possibile ricostruire, sia pure approssimativamente, le condizioni ambientali dei 3 gruppi. il gruppo αα rappresenterebbe condizioni prevalentemente sedimentarie, il gruppo γγ suoli identificabili forse con gli udifluvents della classificazione usda sulla base della distribuzione e dell’abbondanza della sostanza organica, delle figure di idromorfia, di una certa laminazione e della scarsa evoluzione testimoniata dal colore e dalla tipologia della fabric. in alcuni casi potrebbero essere anche aquic udifluvents e vitrandic udifluvents,questi ultimi caratterizzati dall’abbondanza di materiali vetrosi), mentre il gruppoββ‚ rappresenterebbe sia sedimenti palustri che suoli decisamente idromorfi, quali gli hydraquents sulla base delle condizioni riducenti quasi permanenti, con alcune eccezioni già genesi e significato del riempimento della depressione carsica ... ricordate (alfisuoli idromorfi ?). in tutti questi suoli l’azione pedogenetica prendeva il sopravvento attraverso un progressivo ripening (maturazione del sedimento in condizioni idromorfe),dando origine a microstrutture otticamente anisotrope e ad una certa orientazione dei domini argillosi, in parte dovuta tuttavia al periodico disseccamento. 4.2. analisi chimiche e chimico-mineralogiche dei depositi la composizione chimica totale, tramite fluorescenza x ed espressa secondo gli ossidi più significativi di 24 campioni scelti a caso ma rappresentativi dell’intera serie (tab. 5), appare completamente diversa da quella di suoli e sedimenti fluviali (wakatsuki et al., 1977) ma risulta compatibile con quella di prodotti vulcanici medio-basici e in particolare con quelli appartenenti alla provincia comagmatica romana (d’amico et al., 1989) secondo la classificazione riferita da d’argenio et al., 1994, pag 53, basata sulla percentuale di cao e di allumina e le informazioni sulle caratteristiche chimico-mineralogiche (alto tenore in al 2 o 3 , presenza di bario) illustrate da conticelli et al. (2004) e da boari & conticelli (2007), anche se il contenuto in silice e metalli alcalini rivela una forte alterazione del materiale. ne segue che l’intero riempimento, costituito da materiali molto simili tra loro, deve interpretarsi come una sequenza di piroclastiti fortemente alterate e variamente mescolate con apporti dai rilievi circostanti e dal residuo insolubile dei calcari, che si sono sedimentate in ambienti prevalentemente riducenti di tipo lacustrepalustre ma soggetti a periodiche emersioni che ne determinavano una pedogenesi generalmente modesta. il contributo dei calcari è stato tuttavia scarso a causa del loro basso contenuto in residuo insolubile: infatti una analisi calcimetrica di una trentina di litotipi della catena del gran sasso ha fornito valori di caco 3 mediamente superiori all’80 % . per di più, la larga diffusione di depositi piroclastici di varia provenienza nella regione abruzzese è stata da tempo segnalata e studiata (bosi & bertini, 1970; ferrari & malesani, 1973; bosi & locardi , 1991; colica et al., 1993; marcolini et al., 2003; narcisi, 1995; stoppa & rosatelli, 2003; tallini et al., 2002; d’orefice et al., 2006), sebbene vi siano ancora ipotesi differenti circa la loro origine e diffusione. alcuni autori propendono infatti per una origine locale dei materiali mentre altri ritengono che per la maggior parte le piroclastiti siano di provenienza esterna all’abruzzo. al fine di riconoscere caratteristiche comuni utilizzabili per una sommaria classificazione litologica delle piroclastiti, si è applicata una analisi discriminante (codice statistica) a tutti i campioni così da individuare 4 gruppi principali (gr1 = 2 campioni; gr2 = 3 campioni; gr3 =11 campioni; gr4 = 8 campioni (v. fig. 6). gli ultimi 2 gruppi sono sostanzialmente eguali se si eccettua il più alto contenuto in ca del gruppo 3 dovuto probabilmente ad apporti esterni successivi alla messa in posto del deposito. i 4 gruppi sono stati confrontati (tab. 6) con la composizione delle tufiti e dei tefra affioranti entro un raggio di poco più di un centinaio di chilometri dal piano locce, quali stiffe e oricola (tallini et al., 2002 ), pietrasecca (bertolani et al., 2005) e case picconetto in provincia di pescara (marcolini et al.,2003). un’ulteriore indagine è stata eseguita riportando i punti rappresentativi nella fig. 7, dove la % in ossidi di titanio è stata espressa in funzione della % di silice 180 tab. 5 risultati delle analisi chimiche totali eseguite su 24 campioni rappresentativi del riempimento della conca di piano locce. results of chemical total analysis carried out on 24 representative samples. campione mgo al2o3 sio2 p2o5 so3 k2o cao tio2 mno fe2o3 bao pl1 1,620 15,690 42,000 1,000 0,080 2,050 6,310 0,790 0,160 9,810 0,050 pl2 1,800 15,750 43,370 0,640 0,100 2,190 6,200 0,810 0,090 7,560 0,070 pl3 2,150 16,260 42,860 0,650 0,140 2,710 8,740 0,760 0,110 7,780 0,090 pl8 1,220 13,800 36,030 0,440 0,040 1,950 13,440 0,660 0,070 6,450 0,060 pl10 1,500 16,570 43,810 0,570 0,060 2,280 5,350 0,820 0,100 8,910 0,070 pl11 1,480 17,460 44,820 0,650 0,180 2,510 4,170 0,750 0,140 7,100 0,070 pl12 1,390 17,440 43,280 0,700 0,090 2,190 5,610 0,820 0,100 8,030 0,090 pl13 1,410 19,280 45,000 0,690 0,080 2,250 1,120 0,860 0,070 8,920 0,100 pl14 1,520 19,100 45,300 0,760 0,100 2,260 1,960 0,860 0,120 7,990 0,090 pl15 1,450 17,510 42,740 0,690 0,100 2,300 3,070 0,830 0,120 7,820 0,090 pl17 1,320 17,930 50,290 0,490 0,320 5,240 3,430 0,610 0,140 5,910 0,080 pl40 1,550 18,690 41,300 1,820 0,200 1,940 3,290 0,820 0,330 8,570 0,120 pl45 1,290 20,050 41,030 0,650 0,120 2,230 1,520 0,820 0,220 9,710 0,130 pl47 1,390 22,590 46,210 0,960 0,630 2,510 1,750 0,840 0,040 5,020 0,150 pl49 0,830 22,520 46,700 0,460 0,150 2,340 1,300 0,640 0,050 6,020 0,120 pl59 1,500 21,270 43,800 1,050 0,130 2,520 2,500 0,820 0,110 7,330 0,150 pl64 1,860 17,680 45,210 0,690 0,360 2,790 7,480 0,660 0,090 6,820 0,130 pl68 1,660 16,840 43,630 0,670 0,140 3,250 6,590 0,640 0,140 6,900 0,130 pl69 1,070 16,140 50,930 0,350 0,080 6,190 5,820 0,410 0,140 5,100 0,170 pl76 1,250 19,500 45,460 1,120 0,070 2,190 1,370 0,760 0,060 7,460 0,130 pl81 1,690 21,270 43,690 1,300 0,340 2,610 1,880 0,740 0,050 5,980 0,230 pl82 2,630 15,330 37,450 0,620 0,550 5,630 9,440 0,520 0,170 7,330 0,360 pl84 1,460 20,620 43,720 0,560 0,090 2,570 1,200 0,710 0,360 8,150 0,190 pl90 0,860 19,170 51,600 0,310 0,080 4,530 2,830 0,500 5,580 5,580 0,140 d. magaldi et al. secondo una rappresentazione a diagramma usata nello studio delle rocce effusive. in definitiva tabelle e grafico suggeriscono che esiste una discreta somiglianza tra la composizione media di pietrasecca e case picconetto con quella media del gruppo 3-4 di locce e tra quella media di stiffe (e forse oricola) e il gruppo 2; al contrario il gruppo 1, peraltro rappresentato solo da 2 campioni, risulterebbe differente da tutti gli altri. questi risultati tuttavia sono affetti da un elevato margine di incertezza in quanto l’alterazione subita ha senza dubbio provocato la perdita degli elementi più mobili, in conseguenza dei processi di pedogenesi e/o di diagenesi. allo scopo di accertare la provenienza dei materiali vulcanici è stato quindi necessario procedere ad una serie di determinazioni microanalitiche sul vetro, sui plagioclasi e sui pirosseni, utilizzando 16 campioni prelevati ad oltre 30 m di profondità, più freschi di quelli stratigraficamente sovrapposti e contenenti più abbondante materiale vulcanico (vetro, cristalli, e più di rado, frammenti litici di rocce effusive). i livelli vulcanici di piano locce comprendono ceneri fini e grossolane spesso ben selezionate (sorted). alcuni dei livelli apparivano più rimaneggiati, sia per la presenza di cristalli di quarzo eolico che di clasti carbonatici provenienti dai vicini versanti calcarei. le analisi al microscopio elettronico hanno evidenziato come il vetro della stragrande maggioranza dei livelli sia completamente alterato e quindi inutilizzabile per la classificazione chimica dei livelli stessi. solo il campione pl90 proveniente dalla base (78-80 m) della carota, ha dato risultati soddisfacenti. durante la elaborazione di questa ricerca, una indagine successiva condotta a maggiore dettaglio e finalizzata all’acquisizione nello stesso sito del contenuto pollinico della parte più superficiale della carota, ha incontrato un livello centimetrico di ceneri relativamente fresche a 5 m di profondità (livello denominato pl top). pertanto anche questo campione è stato preso in considerazione per la classificazione del vetro . in conformità di queste analisi (tab. 7), il livello pl90 può essere classificato come una latite-trachite. un attento esame dei dati analitici della tabella mostra tuttavia che, pur essendo le analisi nel loro insieme accettabili, presentano valori anormalmente bassi in 181 fig. 6 raggruppamenti (cluster) ottenuti tramite l’analisi discriminante (codice statistica) considerando come variabili il contenuto totale in ossidi. si evidenziano chiaramente 4 gruppi a livello 5 – 10. clusters derived from discriminating analysis (statistica software) using main oxides total content for the samples. there are at 5-10 level 4 main clusters. tab. 6 confronto dei cluster risultanti dalla analisi statistica (codice statistica) con la composizione chimica di alcune piroclastiti dei dintorni di l’aquila. comparison between clusters resulting by statistical analysis (statistica software) and chemical composition of some pyroclastic sediments from l’aquila neighbourhoods. locce pietrasecca oricola stiffe picconetto ossidi (%) gr1 gr2 gr3 gr4 media media media media sio2 36,74 50,94 43,62 44,13 42,37 50,03 48,58 45,46 tio2 0,59 0,51 0,75 0,80 0,81 0,95 1,10 0,95 al2o3 14,57 17,75 16,71 20,11 19,09 12,59 18,99 17,16 fe2o3 2,07 1,66 3,61 2,31 2,26 1,88 2,29 2,63 feo 4,82 3,87 4,07 5,39 5,27 4,40 5,36 6,14 mno 0,12 1,96 0,12 0,15 0,17 n.d. n.d. 0,20 mgo 1,92 1,08 1,68 1,36 3,05 1,74 1,80 3,95 cao 11,44 4,03 6,31 1,91 9,72 4,63 3,06 9,51 na2o n.d. n.d. n.d. n.d. 0,81 1,43 0,43 3,06 k2o 3,79 5,32 2,50 2,31 3,10 4,57 2,06 10,34 p2o5 0,53 0,38 0,70 0,87 0,42 n.d. n.d. 0,57 somma 76,58 87,50 80,07 79,34 87,08 82,21 83,69 100,00 genesi e significato del riempimento della depressione carsica ... sodio (na 2o) e cloro (clo). valori così bassi sono indicativi di incipiente alterazione del vetro che, all’inizio dei processi tende a perdere elementi a largo raggio ionico quali il sodio e il cloro. ne deriva che la somma degli alcali usata nel diagramma di classificazione tas (fig. 8) risulta essere meno attendibile e sicuramente sottostimata rispetto ai valori originari. una correzione della somma degli alcali pari al 3÷4%, sposterebbe infatti la classificazione del vetro nel campo delle tefri-fonoliti e fonoliti (fig. 8). una composizione di questo tipo potrebbe tentativamente essere correlata con le eruzioni pleistoceniche del vulcano di vico, caratterizzate da attività esplosiva di 182 fig. 7 percentuale in ossidi di titanio in funzione della percentuale di silice. percentage of titanium oxide vs. silica percentage. tab.7 analisi del vetro vulcanico prelevato a 5 m di profondità (pl top) e di quello del livello pl90 a 78-80 m di profondità (bottom del sondaggio). a titolo di confronto sono riferite le analisi totali del campione rf95-7 prelevato in adriatico a 450 cm di profondità e quelle della media dei campioni appartenenti, secondo l’elaborazione statistica, al gruppo 2 (v.testo). composition of volcanic glass of pltop (5 m of depth) and of pl 90 sample (78-79 m of depth). as a comparison, total analysis of the sample rf95-7 from the 450 cm depth of adriatic sea and the average composition of the group 2 samples are referred. campioni : 1 2 3 4 5 6 7 8 9 10 media dev. st. rf 95-7 450 cm gruppo 2 sio2 56,11 57,59 58,06 59,17 58,68 58,15 59,81 58,77 57,93 61,11 58,54 1,344 58,27 50,94 tio2 1,31 0,79 0,64 0,57 0,58 0,60 0,28 0,72 0,67 0,21 0,64 0,299 0,44 0,51 al2o3 23,06 19,66 21,06 20,56 21,93 22,22 22,20 20,64 20,31 22,41 21,41 1,106 19,23 17,75 feotot 2,72 4,79 3,48 3,65 3,04 2,64 1,64 3,63 3,80 1,04 3,04 1,094 3,70 2,48 mgo 0,89 1,08 0,75 0,40 0,43 0,67 0,24 0,60 0,86 0,14 0,61 0,302 0,10 1,08 mno 0,10 0,14 0,06 0,18 0,08 0,00 0,00 0,17 0,10 0,00 0,08 0,068 0,65 1,96 cao 7,36 5,59 3,96 3,19 5,57 6,11 4,25 5,42 4,47 4,09 5,00 1,233 3,71 4,03 na2o 2,57 2,97 2,73 4,74 3,54 3,10 3,22 3,81 3,26 4,90 3,48 0,791 4,34 n.d. k2o 5,88 7,35 9,17 7,45 6,04 6,51 8,34 6,17 8,53 5,95 7,14 1,210 9,24 5,32 clo 0,00 0,04 0,10 0,10 0,11 0,00 0,00 0,06 0,07 0,15 0,06 0,053 0,32 n.d. somma 100 100 100,01 100,01 100 100 99,99 99,99 100 100 100 100 84,07 total alkali 8,45 10,32 11,90 12,19 9,58 9,61 11,56 9,98 11,79 10,85 10,62 13,58 alkali ratio 2,29 2,47 3,36 1,57 1,71 2,10 2,59 1,62 2,62 1,21 2,05 2,13 campioni : 1 2 3 4 5 6 7 8 media dev. st. sio2 45,38 46,63 46,5 45,12 44,64 47,62 46,08 45,9 45,98 0,887 tio2 0,92 0,88 0,68 0,96 0,89 0,64 0,85 0,81 0,83 0,106 al2o3 19,88 19,19 20,71 19,11 20,53 20,78 19,72 19,73 19,96 0,612 feotot 8,06 8 7,32 9,05 8,45 7,16 8 7,82 7,98 0,560 mno 0,33 0,46 0,07 0,26 0,37 0,25 0,3 0,14 0,27 0,116 mgo 1,26 1,3 1,29 1,56 1,25 0,78 1,49 1,36 1,28 0,218 cao 11,62 10,79 11,33 12,88 11,87 7,73 11,72 11,62 11,20 1,420 na2o 5,64 6,25 5,38 5,43 6,39 7,22 5,5 5,54 5,92 0,607 k2o 6,72 6,29 6,49 5,47 5,37 7,65 6,14 6,88 6,38 0,699 p2o5 0 0 0 0 0 0 0 0,08 0,01 0,026 clo 0,18 0,2 0,22 0,16 0,26 0,18 0,19 0,13 0,19 0,036 somma 99,99 99,99 99,99 100 100,02 100,01 99,99 100,01 100,00 total alkali 12,36 12,54 11,87 10,9 11,76 14,87 11,64 12,42 alkali ratio 1,191489 1,0064 1,20632 1,007366 0,840376 1,059557 1,116364 1,241877 analisi vetro del campione pl 90 ( circa 80 metri) e del campione pl top (5 m ) pl 90 pl top d. magaldi et al. composizione trachitico-fonolitica (peccerillo, 2005). di conseguenza il campione pl90 potrebbe essere tentativamente correlato con le piroclastiti riconosciute in una carota marina dell’adriatico (livello rf95-7, 450 cm; fig. 8), datate intorno a 170.000 anni fa (calanchi et al., 2008). inoltre, la composizione media dei vetri del livello pl90 sembra abbastanza simile a quella (media) dei 3 campioni appartenenti al gruppo 2 (pl17, pl69 e pl90, tab. 7). il campione pl top è stato classificato come foiditico (fig. 8). sulla base della composizione del vetro, della paragenesi mineralogica (dominata da leucite e clinopirosseno, in assenza di plagioclasio; fig. 9) e delle analisi sem-eds sulle fasi minerali (tab. 7) può essere correlato con l’attività finale del vulcano dei colli albani, e più precisamente con l’eruzione dei peperini, datati a circa 36.000 anni fa (freda et al., 2005). gli altri livelli vulcanici appaiono troppo alterati per essere classificabili sulla base della chimica dei vetri, ma su alcuni di essi è stata effettuata una microanalisi delle fasi minerali (plagioclasi e pirosseni) riferita nelle tabelle 8 e 9, rispettivamente per i sialici e per i femici. la composizione dei minerali dei cinque campioni esaminati (pl48; pl55; pl60; pl64; pl69) indica una stretta affinità con le composizioni delle eruzioni dei vulcani campani (campi flegrei, ischia, procida e somma-vesuvio (peccerillo, 2005), con sanidino dominante nelle fasi sialiche e clinopirosseno in quelle femiche. forse potrebbero essere rappresentativi del gruppo 3-4 anche se il pl69 appartiene statisticamente al gruppo 2. due soli campioni (pl82 e pl74), uno dei quali rientra nel gruppo 1, sulla base della paragenesi mineralogica che contiene abbondante biotite, possono in prima approssimazione essere correlati con l’attività dei vulcani laziali (peccerillo, 2005). dei restanti sei livelli infine non è possibile ipotizzare la sorgente. la tab. 10 riassume le informazioni circa la descrizione e la provenienza dei 16 livelli vulcanoclastici considerati per l’analisi chimico-mineralogica più dettagliata. 5. discussione dei risultati i dati in precedenza esposti sembrano attestare in modo abbastanza chiaro, sia l’origine prevalentemente piroclastica dell’intero riempimento forse fino a notevole profondità, così come sembra avvenuto per il fucino dove un livello di cineriti, con uno spessore di circa 100 m, avrebbe una età di circa 500 mila anni (narcisi, 1995), sia l’età del livello più profondo raggiunto dal sondaggio (circa e forse più di 170.000 anni bp). nell’ipotesi che tutto il materiale piroclastico sia venuto dalla provincia comagmatica romana (apparati vulcanici del lazio e della campania) i depositi più recenti dovrebbero avere meno di 36.000 mila anni e addirittura alcune cineriti potrebbero essere di età proto-storica (sulpizio et al., 2008). anche sul significato paleo-climatico e ambientale da attribuire al deposito possono essere fatte solo considerazioni preliminari. lo studio integrato e multidisciplinare del quaternario ha da qualche tempo evidenziato le strette relazioni che intercorrono tra tipologia dei suoli e condizioni climatiche e biologiche esistenti durante le varie fasi più fredde e più calde dell’attuale (west, 1968; bowen, 1981; birkeland, 1984; mcfadden et al., 1986; birkeland, 1990). in europa settentrionale west (1968) propose la seguente relazione tra clima e suoli in un periodo di tempo compreso tra due “glaciali” successivi: suoli poco evoluti (cataglaciale) – terre brune (interglaciale) podzols sotto foresta (anaglaciale). si può quindi concludere che alcune caratteristiche del suolo riscontrabili a differente scala, da quella di campo a quella microscopica, possano suggerire eventuali cambiamenti nel clima del passato, purché 183 fig. 8 diagramma tas per i campioni pltop e pl90 .a titolo di confronto è mostrata anche la composizione del livello della carota adriatica. the tas classification diagram for some samples: pl top , pl90 and a pyroclastic sediment from the bottom of adriatic sea (450 cm of depth). fig. 9 – analisi al sem-eds su sezione sottile di un livello di tefra a 5 m di profondità (pltop): lc= leucite; cpx= clinopirosseno. sem –eds picture of thin section of sample pl top (5m depth); lc= leucite; cpx= clino-pyroxene. genesi e significato del riempimento della depressione carsica ... 184 t a b . 8 c o m p o si zi o n e c h im ic a d e i f e ld sp a ti d i a lc u n i c a m p io n i c o n m a g g io r c o n te n u to in m in e ra li vu lc a n ic i t ra 3 0 e 8 0 m d i p ro fo n d it à . f e ld sp ar s c h e m ic al c o m p o si ti o n o f sa m p le s c o lle c te d 3 0 t o 8 0 m o f d e p th . a n a lis i c h im ic h e d e i f e ld sp a ti o ss id i ( % ) p l 4 8 p l 5 5 p l 6 0 p l 6 4 p l 6 9 s io 2 4 7 ,9 5 1 ,1 5 3 ,7 5 2 ,2 5 0 ,9 6 3 ,8 6 3 ,7 6 4 ,6 4 6 ,5 6 5 ,0 6 4 ,6 6 4 ,6 6 4 ,7 6 5 ,2 6 3 ,1 4 5 ,9 4 9 ,4 6 3 ,7 6 4 ,2 6 5 ,1 6 6 ,8 6 6 ,2 a l 2 o 3 3 2 ,4 3 0 ,6 2 8 ,1 2 9 ,1 3 0 ,4 1 9 ,3 1 9 ,7 1 9 ,8 3 3 ,0 1 9 ,7 1 9 ,7 1 9 ,6 1 9 ,4 2 0 ,3 1 9 ,7 3 2 ,5 3 1 ,7 1 9 ,6 2 0 ,2 2 0 ,1 1 9 ,9 1 9 ,9 f e o to t 0 ,6 0 ,4 0 ,5 0 ,9 1 ,0 0 ,2 0 ,4 0 ,5 0 ,7 0 ,3 0 ,3 0 ,3 0 ,3 0 ,2 0 ,5 0 ,8 0 ,7 0 ,4 0 ,3 0 ,3 0 ,4 0 ,3 c a o 1 6 ,5 1 3 ,3 1 1 ,5 1 2 ,3 1 3 ,3 0 ,5 1 ,1 1 ,1 1 6 ,7 0 ,5 0 ,9 0 ,6 0 ,5 0 ,8 1 ,2 1 6 ,9 1 4 ,7 1 ,1 0 ,4 0 ,4 0 ,0 0 ,1 n a 2 o 2 ,0 3 ,6 4 ,5 3 ,9 3 ,0 2 ,0 3 ,7 4 ,0 1 ,7 4 ,7 4 ,9 4 ,6 5 ,3 6 ,9 3 ,6 1 ,6 2 ,7 3 ,7 7 ,2 7 ,3 6 ,9 6 ,8 k 2 o 0 ,2 0 ,6 0 ,9 0 ,9 0 ,7 1 3 ,5 1 0 ,6 9 ,9 1 ,3 9 ,9 9 ,6 1 0 ,3 9 ,7 6 ,4 1 0 ,6 1 ,2 0 ,6 1 1 ,3 7 ,1 6 ,6 6 ,1 6 ,6 t o ta le 9 9 ,6 9 9 ,6 9 9 ,2 9 9 ,3 9 9 ,2 9 9 ,2 9 9 ,2 9 9 ,9 9 9 ,9 1 0 0 ,0 1 0 0 ,0 9 9 ,8 9 9 ,9 9 9 ,9 9 8 ,7 9 8 ,9 9 9 ,7 9 9 ,7 9 9 ,4 9 9 ,9 1 0 0 ,0 1 0 0 ,0 t a b . 9 c o m p o si zi o n e c h im ic a d e i p ir o ss e n i d i a lc u n i c a m p io n i c o n m a g g io r c o n te n u to in m in e ra li vu lc a n ic i t ra 3 0 e 8 0 m d i p ro fo n d it à . p yr o xe n e s c h e m ic al c o m p o si ti o n o f sa m p le s c o lle c te d 3 0 t o 8 0 m o f d e p th .. a n a lis i c h im ic h e d e i p ir o ss e n i o ss id i ( % ) p l 4 8 p l 5 5 p l 6 0 p l 6 4 p l 6 9 s io 2 4 8 ,7 4 7 ,6 4 9 ,0 5 0 ,5 5 0 ,7 5 2 ,7 5 0 ,5 5 1 ,2 4 9 ,9 5 0 ,8 5 0 ,2 5 1 ,2 5 2 ,5 5 1 ,3 5 3 ,1 5 1 ,5 5 1 ,5 5 1 ,6 5 ,6 5 0 ,4 4 8 ,1 4 7 ,8 t io 2 1 ,4 1 ,7 1 ,2 1 ,0 1 ,3 0 ,4 0 ,8 0 ,7 0 ,7 1 ,0 1 ,1 0 ,6 1 ,4 1 ,0 0 ,3 0 ,7 0 ,6 0 ,8 0 ,7 0 ,7 1 ,4 1 ,7 a l 2 o 3 5 ,2 7 ,3 6 ,4 3 ,1 4 ,2 2 ,1 2 ,9 2 ,0 3 ,2 1 ,3 2 ,2 1 ,5 0 ,5 1 ,3 2 ,5 3 ,6 3 ,5 3 ,4 2 ,4 2 ,6 5 ,7 6 ,2 f e o to t 8 ,4 8 ,1 7 ,1 7 ,2 7 ,8 3 ,7 9 ,3 9 ,2 7 ,8 1 0 ,0 1 0 ,1 8 ,7 2 3 ,4 9 ,9 3 ,7 4 ,9 4 ,8 7 ,2 7 ,8 7 ,8 7 ,6 7 ,7 m n o 0 ,2 0 ,1 0 ,0 0 ,1 0 ,1 0 ,1 0 ,7 0 ,9 0 ,2 1 ,4 1 ,2 1 ,1 1 ,9 1 ,5 0 ,2 0 ,1 0 ,1 0 ,2 0 ,6 0 ,4 0 ,2 0 ,1 m g o 1 3 ,2 1 2 ,5 1 3 ,1 1 5 ,2 1 3 ,6 1 6 ,7 1 2 ,6 1 3 ,1 1 3 ,2 1 2 ,6 1 2 ,4 1 3 ,8 2 ,4 1 2 ,5 1 6 ,5 1 5 ,6 1 6 ,4 1 4 ,3 1 5 ,1 1 5 ,1 1 4 ,2 1 4 ,0 c a o 2 2 ,4 2 2 ,4 2 2 ,8 2 2 ,3 2 2 ,0 2 3 ,7 2 2 ,3 2 2 ,0 2 3 ,8 2 0 ,3 2 1 ,5 2 2 ,0 8 ,6 2 0 ,5 2 3 ,5 2 3 ,1 2 2 ,3 2 2 ,1 2 2 ,2 2 2 ,4 2 2 ,6 2 2 ,2 n a 2 o 0 ,3 0 ,2 0 ,3 0 ,3 2 ,0 0 .1 0 ,8 0 ,7 0 ,4 1 ,6 1 ,2 1 ,0 8 ,8 1 ,6 0 ,1 0 ,1 0 ,2 0 ,3 0 ,7 0 ,6 0 ,3 0 ,3 t o ta le 9 9 ,8 9 9 ,9 9 9 ,9 9 9 ,7 9 9 ,9 9 9 ,4 9 9 ,8 9 9 ,7 9 9 ,1 9 9 ,1 9 9 ,9 9 9 ,8 9 9 ,5 9 9 ,5 1 0 0 ,0 9 9 ,7 9 9 ,4 9 9 ,9 1 0 0 ,0 1 0 0 ,0 1 0 0 ,0 1 0 0 ,0 d. magaldi et al. 185 tab. 10 descrizione riassuntiva e ipotesi di provenienza dei materiali vulcanici sulla base delle analisi chimico-mineralogiche eseguite su 17 campioni tra 5 e 80 m di profondità. short description of examined volcanic glass and provenance hypothesis for 17 samples 5 to 80 m of depth. campione profondità colore descrizione sorgente pl top 5,0 m n3 ceneri grossolane di colore grigio scuro-nero. l'analisi al binoculare mostra colli albani dark gray che le particelle sono poco vescicolate e porfiriche. ci sono cristalli sialici e (eruzione dei femici sciolti. l'analisi al microscopio elettronico mostra che il vetro peperini) è di composizione foiditica, con massa di fondo cristallina. la paragenesi 36 ka bp è dominata dalla leucite+clinopirosseno, con raro sanidino. pl 48 30-28,6 m 5yr 5/2 ceneri fini e grossolane di colore marroncino, compatte. l’analisi al binoculare la composizione pale brown mostra vetro, piccoli litici carbonatici e cristalli sialici e femici. l’analisi dei minerali al microscopio elettronico mostra che il vetro è completamente alterato. sembra indicare le composizioni delle fasi minerali indicano che la paragenesi dominante è una sorgente plagioclasio e clinopirosseno campana pl 49 31,2-30,6 m 10yr 8/2 ceneri fini di colore giallastro. l’analisi al binoculare mostra che il vetro è sconosciuta very pale scarso e molto alterato. presenza di cristalli sialici e femici. orange pl 51 32,2-31,8 m 5y 7/2 ceneri grossolane di colore grigio con abbondanti inclusi carbonatici. sconosciuta yellowish l’analisi al binoculare mostra che il vetro è scarso e molto alterato. deposito gray abbondanti cristalli femici e minori sialici. rimaneggiato in ambiente subaereo pl 55 35-33,9 m 5y 7/2 ceneri fini e grossolane mediamente compatte di colore grigio. la composizione yellowish l’analisi al binoculare mostra presenza di vetro e cristalli sialici e femici. dei minerali gray l’analisi al microscopio elettronico mostra che il vetro è completamente sembra indicare alterato. le composizioni delle fasi minerali indicano che la paragenesi una sorgente dominante è sanidino e clinopirosseno con minore plagioclasio. campana pl 60 39,4-36,4 m 10yr 6/2 ceneri grossolane sciolte di colore marroncino con piccoli inclusi carbonatici. la composizione pale l’analisi al binoculare mostra presenza di vetro e cristalli sialici e femici. dei minerali yellowish l’analisi al microscopio elettronico mostra che il vetro è completamente alterato. sembra indicare brown le composizioni delle fasi minerali indicano che la paragenesi dominante una sorgente è sanidino e clinopirosseno. campana pl 64 42,7-42,1 m 5y 7/2 cenere fine e grossolana compatta ma non cementata di colore grigio. la composizione yellowish l’analisi al binoculare mostra vetro mal conservato e cristalli sia sialici che femici. dei minerali gray l’analisi al microscopio elettronico delle fasi minerali mostra la presenza sembra indicare di sanidino, clinopirosseno e minore plagioclasio. una sorgente campana pl 66 44-43,3 m 5y 5/2 ceneri grossolane di colore grigio scuro. sconosciuta light olive l’analisi al binoculare mostra particelle molto arrotondate e presenza di deposito grey cristalli di quarzo di colore biancastro. rimaneggiato in ambiente subaereo pl 68 46-44,5 m 5y 7/2 ceneri fini e grossolane simili alle precedenti, di cui costituiscono la parte stessa eruzione light olive finale e probabilmente più rimaneggiata, come testimoniato dagli abbondanti del pl 69 gray clasti carbonatici del substrato inglobati dalle ceneri. pl 69 46,5-46 m 2.5y 7/2 ceneri fini e grossolane di colore grigio. ci sono clasti carbonatici del la composizione light gray substrato inglobati nelle ceneri. l’analisi al binoculare mostra vetro, dei minerali litici lavici e abbondanti cristalli sia sialici che femici. l’analisi al microscopio sembra indicare elettronico mostra che il vetro è completamente alterato. le composizioni una sorgente delle fasi minerali indicano che la paragenesi dominante è sanidino e clinopirosseno. campana. pl 72 54-52,15 m 10yr 6/4 ceneri fini ben selezionate di colore marroncino. il materiale è simile a quello sconosciuta light del livello precedente. il vetro è completamente alterato yellowish brown pl 73 56-54 m 10yr 5/6 ceneri molto fini e ben selezionate di colore marroncino. al binoculare si sconosciuta yellowish notano vetro e cristalli sialici e femici non abbondanti. l’analisi al microscopio brown elettronico mostra che il vetro è completamente alterato. pl 74 56,8-56,1 m 10yr 7/2 cenere fine e grossolana di colore grigio, con screziature di colore marrone. la paragenesi light gray l’analisi al binoculare mostra vetro, abbondanti cristalli di biotite, mineralogica cristalli sialici (sanidino) e femici (clinopirosseno). l’analisi al microscopio suggerisce una elettronico mostra che il vetro è completamente alterato. sorgente nei vulcani laziali pl 82 69,5-67,5 m 2.5y 6/1 ceneri grossolane di colore grigio. l’analisi al binoculare evidenzia la presenza la paragenesi gray di vetro e di molti cristalli di biotite, insieme ad altri cristalli femici mineralogica (clinopirosseni) e sialici incolori (sanidini) o lattiginosi. l’analisi al microscopio suggerisce una elettronico mostra che il vetro è completamente alterato. sorgente nei vulcani laziali pl 85 73-72 m 10yr 6/2 ceneri grossolane di colore marrone chiaro. al binoculare si distingue vetro sconosciuta pale lattiginoso, litici lavici e cristalli sialici e femici. alcuni cristalli sembrano deposito yellowish abrasi e rimaneggiati. presenza di alcuni clasti dal substrato carbonatico. rimaneggiato brown l’analisi al microscopio elettronico indica che il vetro è completamente alterato in ambiente e la composizione originaria non è ipotizzabile. subaereo pl 89 78-76,10 m 10yr 8/1 ceneri fini ben selezionate di colore chiaro. al binoculare si distingue vetro lattiginoso, sconosciuta white e piccoli cristalli sialici e femici. l’analisi al microscopio elettronico indica che il vetro è completamente alterato e la composizione originaria non è ipotizzabile. pl 90 79-80 m 5y 7/1 ceneri fini e grossolane di colore grigio chiaro. il deposito è addensato ma non attività del light gray cementato. presenza di lapilli accrezionali. al binoculare appare formato da vetro, vulcano di vico cristalli sialici ialini e femici. l’analisi al microscopio elettronico indica che il vetro ha più vecchia composizione trachitico-latitica a causa di un impoverimento in alcali dovuto ad di 170 ka bp alterazione incipiente. i cristalli sono prevalentemente sanidino e clinopirosseno genesi e significato del riempimento della depressione carsica ... capaci di una sufficiente persistenza durante le mutevoli condizioni ambientali (yaalon, 1971; birkeland, 1990). alcuni livelli, infatti, a circa 30 m di profondità mostrano alcune forme contorte (involutions). e’ quindi probabile che queste forme siano state determinate da processi periglaciali, che hanno agito su un suolo con qualche clay skin sul quale tuttavia non sono ancora state eseguiti analisi polliniche. al contrario alcune analisi polliniche, condotte puramente a titolo esplorativo da c.a. accorsi su alcuni campioni più ricchi di materia organica, rivelano momenti più freddi dell’attuale tra 45 e 67 m di profondità. in molti casi il diverso contenuto in argilla pedogenetica può indicare periodi con diversa umidità del clima (reheis, 1987 in birkeland, 1990 ). anche dalla sedimentologia risultano informazioni che vanno a corroborare i dati ottenuti dalla pedologia. secondo ortolani & pagliuca (in crescenti, 2005) i depositi alluvionali, che nel cilento seppelliscono reperti archeologici romani e medievali, sono indicatori di periodi freddo-umidi, al contrario delle sabbie di duna costiera che rappresenterebbero invece periodi più aridi. partendo da queste considerazioni si è voluto comprendere il significato delle variazioni del contenuto di argilla e di sostanza organica in rapporto alla profondità. come è noto da tempo, l’alterazione dei materiali piroclastici fini è generalmente molto veloce e può dare origine a minerali argillosi amorfi e cristallini quali allofane, imogolite, halloysite ed altri. l’argilla granulometrica dovrebbe quindi rappresentare, almeno in parte, minerali argillosi di neoformazione e la sua frequenza in relazione alla profondità, potrebbe indicare un diverso grado di alterazione del materiale primario, alterazione la cui entità è strettamente legata alla disponibilità di acqua e di silice e infine alla temperatura dell’ambiente circostante. può darsi quindi che il diagramma del rapporto limo/argilla in funzione della profondità, peraltro con andamento approssimativamente inverso a quello della % di sostanza organica (fig. 10) e quasi del tutto analogo a quello del vicino riempimento di piano lucchiano (magaldi et al., 2006) , possa interpretarsi come un indice paleo-climatico, dove i valori più bassi indicherebbero periodi più favorevoli alla pedogenesi e alla diffusione della vegetazione (e quindi più caldi e più umidi), al contrario dei valori più alti che potrebbero testimoniare periodi più freddi e probabilmente più aridi. l’aridità sarebbe provata dalla neoformazione di noduli e concrezioni di carbonato di calcio, presenti nei depositi situati tra i 30 e i 50 m di profondità. 6. conclusioni durante il quaternario gran parte dell’italia centromeridionale fu investita da materiali cineritici di origine vulcanica provenienti per via eolica prevalentemente dai centri di emissione della provincia comagmatica romana (peccerillo, 2005), caratterizzata dall’elevato contenuto in potassio. le principali catene carbonatiche dell’appennino disposte all’incirca parallelamente alla costa tirrenica furono così ricoperte da coltri vulcanoclastiche in spessori variabilissimi, più spessi nelle zone vallive e nelle depressioni di origine carsica (m. simbruini, m. lepini, m. aurunci), dove il colluvionamento iniziato subito dopo la deposizione e proseguito intensamente in seguito determinò un notevole accumulo di materiali. ad esempio nella zona di capestrano (santa pelagia) un sondaggio privato sul riempimento di una conca carsica, ha raggiunto la roccia carbonatica dopo circa 150 m, attraversando una successione di depositi fluvio-lacustri e vulcanoclastici, a volte pedogenizzati. questo processo è stato particolarmente intenso sulla catena del gran sasso e sulle vallate immediatamente adiacenti sia a est che ad ovest del rilievo principale, dove la diffusa morfologia carsica ha agito come trappola e zona di conservazione dei depositi, rallentando così la normale azione erosiva agente sui versanti più acclivi. tutti i risultati ottenuti testimoniano chiaramente che la zona di piano locce è stata interessata in vari momenti del quaternario antico da una sequenza di eventi sedimentari (palustri e piroclastici) e pedogenetici, sicuramente iniziati prima degli ultimi 200mila anni, associati a variazioni climatiche in un ambiente di alta montagna, variazioni che sono evidenziate in particolare dall’andamento del contenuto in sostanza organica con la profondità e dalla sua relazione con il rapporto limo/argilla e infine dalle figure micromorfologiche, che in alcuni livelli sono sicuramente attribuibili a fenomenologie periglaciali. quando le condizioni climatico–vegetazionali consentirono l’instaurarsi di processi pedogenetici, si formarono suoli poco evoluti, fortemente condizionati da idromorfia quasi permanente. solo in pochi casi, verso il centro della successione, si sono osservate caratteristiche micromorfologiche sicuramente attribuibili a suoli più sviluppati, riferibili a intervalli di tempo di stasi più lunghi, forse con orizzonte argillico (aqualfs? boralfs?). al riempimento della depressione, 186 fig. 10 percentuale di sostanza organica dei campioni e andamento del rapporto limo/argilla in funzione della profondità di campionamento. organic matter and silt/clay ratio for the whole stratigraphyc column d. magaldi et al. insieme a quelli di limitati e temporanei corsi d’acqua torrentizi, hanno contribuito, sia pure in minima parte apporti colluviali e/o eolici da suoli maggiormente evoluti e di ambiente climatico differente (“terre rosse” tipo xeralfs o ustalfs ), ancora presenti come “suoli residuali ” nelle vallate vicine (magaldi & tallini , 2000). ringraziamenti il coordinatore-responsabile del progetto, finanziato con gli ultimi fondi del cluster c11 b del miur (ambiente terrestre) esprime la sua gratitudine alla direzione dell’ente parco nazionale del gran sasso e dei monti della laga per aver concesso l’esecuzione dei sondaggi e alla fondazione della cassa di risparmio di l’aquila per il notevole contributo corrisposto alcuni anni fa e destinato all’acquisto di un modernissimo microscopio da petrografia, strumento indispensabile per lo svolgimento della presente ricerca. un ringraziamento particolare alla dr.ssa francesca tescari per il contributo dato alla revisione della parte relativa alla micromorfologia del suolo e all’ing. danilo ranalli per la preparazione del cd fotografico. si ringraziano infine l’ing. bruno taddei e il per. ind. algerio giangiuliani, rispettivamente, per l’assistenza prestata alla esecuzione dei due carotaggi e al loro campionamento. bibliografia apat (2006) carta geologica d’italia alla scala 1:50.000: l’aquila. s.el.ca., firenze. bertini t., bosi c. & galadini f. 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(1987) saharan dust and desert loess: effect on surrounding soils. j.afr.earth sci., 6, 569-571. 188 ms. ricevuto l’11 maggio 2009 testo definitivo ricevuto il 5 agosto 2009 ms. received: may 11, 2009 final text received: august 5, 2009 d. magaldi et al. sess 1_160211.pub il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 detecting and modeling active structures in northern calabria: new insights from drainage network morphometric analysis. enrico santoro1, luigi ferranti2, carmelo monaco1, frank j. pazzaglia3 & pierfrancesco burrato4 1dipartimento di scienze geologiche, università di catania, catania 2dipartimento di scienze della terra, università “federico ii”, napoli 3department of earth and environmental science, lehigh university, bethlehem (pa) 4sezione di sismologia e tettonofisica, i.n.g.v., roma corresponding author: e. santoro <enrico.santoro@hotmail.it> abstract: santoro e. et al., detecting and modeling active structures in northern calabria: new insights from drainage network morphometric analysis.(it issn 0394-3356, 2011). a detailed morphometric analysis of the drainage network on the eastern side of the pollino mountain range (northeastern calabria) was performed in order to gain new insights on the active tectonic frame, the landscape evolution state and the response time of the hydrographic network to the tectonic deformations. riassunto: santoro e. et al., individuazione e modellazione di strutture attive in calabria settentrionale: nuove evidenze dall’analisi morfometrica del reticolo idrografico. (it issn 0394-3356, 2011). un’analisi morfometrica di dettaglio delle principali fiumare che drenano il versante orientale del pollino (calabria nordorientale) ha consentito di acquisire nuove conoscenze riguardo il quadro tettonico attivo, lo stato evolutivo del paesaggio e i tempi di risposta del sistema idrografico alle deformazioni imposte dalla tettonica. key words: morphometric analysis, knickpoints, active transpression, north-eastern calabria. parole chiave: analisi morfometrica, convessità, transpressione attiva, calabria nord-orientale.  the longitudinal profile of bedrock channels may yield valuable information about the landscape vertical deformation processes, the rock mass erosional strength, the eustatic cycles and the climatic factors controlling the landforms. a number of studies have been successful in the evaluation of recent deformation features using quantitative analysis of longitudinal profiles (e.g., merritts & vincent, 1989); the realization of this goal, however, remain limited to the areas were local calibration of model parameters is possible (kirby & whipple, 2001). in this study, inspired by previous results obtained through the mapping of the marine terraces and the reconstruction of the relative paleo-shorelines, we have performed a detailed morphometric analysis of the drainage network on the eastern side of the pollino mountain range (north-eastern calabria; fig. 1). the uniform coastal lithology and climate allow us to isolate the tectonic signal from the fluvial morphometric analysis. this region is located on the north-eastern tip of the calabrian arc, which lies above the westerlyplunging ionian slab, and a combination of lithospheric and crustal processes concurred to rapid late quaternary uplift. ferranti et al. (2009) and santoro et al. (2009) mapped ten terrace orders up to 663 m a.s.l., correlated between the coastal slopes of pollino range across the sibari plain, facing the ionian sea side of north-eastern calabria and eastern basilicata. based on the terrace chronology, uplift along the pollino coastal range, in the last ~600 ka, occurred at an average rate of 1 mm/a, but was characterized by the alternation of more rapid (~2.2 mm/a) and slower (~0.7 mm/a) periods of displacement. besides, spatial variability in uplift rates is recorded by the deformation profile of terraces parallel to the coast, which document small-wavelength (~20 km) and amplitude (up to ~100 m) local undulations superposed to the regional uplift pattern, which is the dominant tectonic signal (santoro et al., 2009). based on the structural, geodetic, geophysical and seismic data the paleo-shorelines undulations were interpreted as fault-propagation folds linked to the transpressive shear zones, no-se directed, that affected the region since the early pleistocene. this hypothesis is confirmed by the results of the numeric modelling of the shear zones cutting the coastal area where the major deformations were identified. the good match between the modelled vertical co-seismic deformation and the paleoshorelines deformation profiles testifies that the transpressional regime was active during the middle-upper pleistocene. through an iterative comparison between the paleo-shoreline profiles and the vertical co-seismic deformation it was possible to define the geometric and kinematic fault parameters that best explain the marine terraces deformation. the final deformation model predicts the active uplift of two anticlines along the southeastern flank of the pollino range and the valsinni 60 62 61 ridge (hereafter named pollino and valsinni anticlines, respectively; fig. 1). the morphometric analysis was performed to test and improve the above mentioned deformation model. linear regressions of the logarithms of channel gradient and drainage area data was used to find convexities (knickpoints) and to determine, the concavity index (θ) and the steepness index (ks). the method is based on the shear-stress incision model, predicated on the hypothesis that the bedrock-channel-erosion rate (e), in volume per unit channel area, is a power-law function of basal shear stress (τb): e = kbτb a, (1) where kb is a dimensional coefficient dependent on dominant erosion process, rock resistance and sediment load and a is a positive, processdependent constant. combining the shear-stress incision model with a statement of conservation of mass, assuming that uplift and erosion are uniform in a drainage basin and solving for the river longitudinal slope is possible to write: s = ksa -θ. (2) the coefficient ks (steepness index) and the exponent θ (concavity index) are, respectively, the gradient-axis-intercept and the slope of the linear regressions through the logarithms of channel gradient and drainage area data. we limited our analysis to the bedrock channel region; the results obtained from area controlled by hillslope/colluvial or alluvial processes are, indeed, not reliable. the rivers longitudinal profiles, extracted from dem 10x10 m, were corrected averaging the elevation through a mobile 200 m window, in order to reduce the gradient data dispersion derived by dem errors. following snyder et al. (2000) and whipple (2004) we used a fixed reference concavity (θ = 0.45) in order to calculate a normalized steepness index (ksn); this permitted the comparison between channels characterized by different drainage areas (e.g., kirby et al., 2003). the ksn values increase regularly toward the pollino and valsinni anticlines; in other words, the rivers flowing through the areas that are affected by the higher uplift rates tend to establish a steeper longitudinal profile in order to have the energy sufficient to erode the uplifting tectonic barrier. several knickpoints (steeper channel segments characterized by convexupward shapes and θ<0) were detected along the longitudinal profiles of the trunk streams. being the analyzed rivers adjusted to the sea level (drainage network base level), it is reasonable to hypothesize that some of the knickpoints are related to the glacialinterglacial quaternary cycles. to test this idea, for each knickpoint the reconstruction of the interglacial profile was performed through the ks and the θ values calculated for the respective river. an eustatic origin was considered valid if: 1. the paleolongitudinal profile crosses a marine terrace; 2. at least three knickpoints are related to the same marine terrace (same eustatic regression); 3. the knickpoints correlated to the same eustatic cycle are characterized by migration rates and positions that are in direct relationship with the landward drainage area. for some of the knickpoints the eustatic origin is confirmed by the presence of fluvial terraces aligned with the relative paleolongitudinal profiles; the terraces are, reasonably, the consequence of the erosive wave triggered by the eustatic regression and progressively transmitted to the entire drainage basin through the knickpoint landward migration. generally, the elevation of a knickpoint genetically related to an eustatic sea level regression is influenced by the drainage fig. 1, knickpoints elevation and incision rates compared with the deformation model. altezze dei knickpoints e tassi di incisione fluviali comparati con il modello di deformazione.  detecting and modeling active structures in northern ... 62 ms. received: testo ricevuto il area (migration rate) and the trunk stream longitudinal gradient. as a consequence, holding constant the drainage area the knickpoint elevation can be influenced by gradient changes determined .by differential uplift rates; the higher the uplift rate the higher the gradient and the knickpoint elevation. in the study area this theoretical prediction is perfectly confirmed: all the knickpoints related to the same marine terrace are always characterized by an increase of the elevations toward the pollino and valsinni anticlines (fig. 1) where the higher uplift rates determine a rise of the river gradients. the maximum difference in elevation between the paleo-longitudinal profiles and the present riverbed was evaluated in order to determine the mean fluvial incision rates. as forecasted by the deformation model, the rivers flowing through the pollino and valsinni anticlines are characterized by the higher incision rates (fig. 1). these streams, in order to adjust their equilibrium profile disturbed by the tectonic deformation, increase their gradient and vertically incise through their valley. finally, based on the migration rates, it was possible to determine the drainage network response time considered to be the time necessary for a convexity to migrate through the entire drainage basin. all the analyzed rivers show a low response time (~105 yr) that highlights the youthfulness of the tectonic deformation; indeed, all the tectonic signals older than 105 yr can be considered completely erased by the fluvial erosive processes. the longitudinal profile analysis have permitted to confirm the results independently reached with the marine terraces, the structural and geophysical analysis and the fault modelling, evidencing that compressional regime is still active in this sector of the southern apennines. references ferranti l., santoro e., mazzella m.e., monaco c. & morelli d. (2009) active transpression in the northern calabria apennines, southern italy. tectonophysics, 476 (1-2), 226-251. kirby e., whipple k.x., tang w. & zhiliang c. (2003) – distribution of active rock uplift along the eastern margin of the tibetan plateau: inferences from bedrock channel longitudinal profiles. j. geophys. res., 108 (b4), 2217, doi: 10.1029/2001jb000861. kirby e. & whipple k. (2001) – quantifying differential rock-uplift rates via stream profile analysis. geology, 29 (5), 415-418. merritts d. & vincent k.r. (1989) – geomorphic response of coastal streams to low, intermediate and high rates of uplift, mendocino triple junction region, northern california. geol. soc. am. bull., 101, 13731388. santoro e., mazzella m.e., ferranti l., randisi a., napolitano e., rittner s. & radtke u. (2009) raised coastal terraces along the ionian sea coast of northern calabria, italy, suggest space and time variability of tectonic uplift rates. quaternary international, 206, 78-101. snyder n.p., whipple k.x., tucker g.e. & merritts d.j. (2000) – landscape response to tectonic forcing: digital elevation model analysis of stream profiles in mendocino triple junction region, northern california. geol. soc. am. bull., 112, 1250-1263. whipple k.x. (2004) – bedrock rivers and the geomorphology of active orogens. ann. rev. earth planet sci., 32, 151-185. january 13, 2011 13 gennaio 2011 e. santoro et al. imp.cucci_tertulliani i terrazzi marini nell’area di capo vaticano (arco calabro): solo un record di sollevamento regionale o anche di deformazione cosismica? luigi cucci & andrea tertulliani istituto nazionale di geofisica e vulcanologia, sezione sismologia e tettonofisica, via di vigna murata, 605 – 00143 roma e-mail: cucci@ingv.it, tertul@ingv.it riassunto: cucci l. & tertulliani a., i terrazzi marini nell’area di capo vaticano (arco calabro): solo un record di sollevamento regionale o anche di deformazione cosismica? (it issn 0394-3356, 2006). in questo lavoro presentiamo uno studio di dettaglio dei terrazzi nell’area di capo vaticano (calabria tirrenica), insieme ad una revisione del piano quotato del terremoto del 1905. il campo macrosismico rivisitato conferma che le massime intensità sono state raggiunte in un’area estesa fra vibo valentia e capo vaticano per un evento di magnitudo m=6.8±0.2; la più probabile struttura sismogenetica responsabile dell’evento è una faglia di dimensioni 36x14 km e direzione 80° (faglia “macrosismica”). lo studio dei terrazzi ha invece messo in evidenza che l’area in studio è in sollevamento attivo da almeno 700.000 anni, che tale processo è in lieve ma progressivo aumento nel tempo, con tassi negli ultimi 124.000 leggermente inferiori a ~1 mm/anno, e che a settentrione di capo vaticano i terrazzi sono chiaramente tiltati verso nord. inoltre, le variazioni di quota osservate nelle paleolinee di riva a cavallo di una struttura tettonica ad andamento ono-ese indicano che tale struttura (faglia “geologica”) è attiva da almeno 330.000 anni, con tassi verticali medi che variano negli ultimi 215.000 anni fra 0,12 e 0,16 mm/anno. per verificare quanto ognuna di queste due strutture fosse congruente con gli elementi geologici, topografici e macrosismici a disposizione, abbiamo calcolato il campo di deformazione indotto in superficie dall’azione della faglia “macrosismica” rispetto a quello della faglia “geologica”. il confronto qualitativo fra le deformazioni aspettate evidenzia una buona congruenza nella risposta della faglia “geologica” e rafforza l’ipotesi che a tale struttura possa essere associato l’evento del 1905, anche alla luce di recenti localizzazioni ipocentrali ottenute da inversione di registrazioni storiche. abstract: cucci l. & tertulliani a., the marine terraces in the area of capo vaticano (calabrian arc): only a record of regional uplift or even of coseismic deformation? (it issn 0394-3356, 2006). the area of capo vaticano in western calabria displays a well-developed suite of marine terraces. this same region was hit in 1905 by one of the strongest – and still poorly cleared – earthquakes of the instrumental era. our revision of the intensity map of the event confirms the location of the most damaged area (between vibo valentia and capo vaticano) and indicates that the most likely source is a n80°-trending, 36(l) x 14(w) km structure with a macroseismic magnitude m=6.8±0.2. a detailed study of the marine terraces shows that sustained uplift has been the long-term dominant process of tectonic deformation in this area over the past 700 kyr, with an average long-term uplift rate slightly less than 1.0 mm/yr, and that terraces are tilted northward. moreover, the four lowest paleoshorelines are displaced by a wnw-ese trending fault, that indicates that the fault is active in the last 215,000 years with mean vertical slip rates of 0.12-0.16 mm/yr. finally, we perform a qualitative comparison between the set of geological, topographic and macroseismic data available and the expected deformation fileds induced by each of the afore-mentioned faults. it is therefore suggested that the good response of the wnw-trending fault strenghtens the hypothesis of this structure as the source of the 1905 earthquake. parole chiave: terrazzi marini – arco calabro – sismicità – capo vaticano. keywords: marine terraces – calabrian arc – seismicity – capo vaticano. il quaternario italian journal of quaternary sciences 19(1), 2006 89-101 introduzione l’area di capo vaticano nella provincia calabrese di vibo valentia fu colpita cento anni fa da uno dei più forti, ma poco chiariti, terremoti italiani del secolo passato, che produsse gravi danni in una vasta zona della calabria centrale, con massimo risentimento lungo la costa tirrenica fra lametia e nicotera. nonostante la sua energia (maw=7.1; gruppo di lavoro cpti (2004); ms=7.5 margottini et al., (1993); i=x-xi mcs), la sorgente dell’evento dell’8 settembre 1905 è ancora dibattuta, poiché gli autori hanno proposto diversi epicentri sia a mare che a terra, senza associarli in modo univoco a faglie sismogenetiche conosciute. in questa stessa area è ben visibile una notevole sequenza di terrazzi marini, che sono uno degli effetti più spettacolari del sollevamento quaternario lungo le coste dell’arco calabro. antiche linee di riva sollevate sono presenti in tutta la regione sia lungo la costa tirrenica (fuscaldo, amantea, capo vaticano), che lungo quella ionica (sibari, crotone) così come lungo le coste dello stretto di messina. in questo lavoro presentiamo uno studio di dettaglio dei terrazzi nell’area di capo vaticano, lungo un tratto di ~60 km di costa, insieme ad una revisione degli effetti del terremoto del 1905. confrontiamo quindi i dati geologici di sollevamento e deformazione locale evidenziati dai terrazzi marini con lo scenario del terremoto desunto dalle osservazioni macrosismiche, per cercare di valutare l’attività di alcune strutture tettoniche e di verificarne la compatibilità con l’evento del 1905. 90 l. cucci & a. tertulliani geologia e sismotettonica il promontorio di capo vaticano è un alto strutturale localizzato nella parte centrale dell’arco calabro, in un’area chiave per comprendere alcuni processi direttamente connessi alla subduzione di litosfera oceanica ionica nel piano di benioff del tirreno meridionale. ad esempio, il probabile detachment dello slab in subduzione (spakman et al. 1993; westaway, 1993; hyppolite et al. 1994; gvirtzmann & nur, 1999) o l’arretramento dello slab stesso (malinverno & ryan, 1986; giunchi et al. 1996; meletti et al. 2000; barberi et al. 2004) sono alternativamente proposti dagli autori come responsabili dell’estensione attiva instauratasi perpendicolarmente alla catena e del rapido sollevamento dell’italia meridionale (gignoux, 1913; bousquet, 1973; brogan et al. 1975; aïfa et al. 1988; westaway, 1993; bordoni & valensise, 1998; ferranti et al. 2006). il basamento cristallino che costituisce l’ossatura del promontorio di capo vaticano è rappresentato da graniti, gneiss e quarzofilliti, coperti da affioramenti discontinui di carbonati miocenici-pliocenici e da depositi terrigeni. in tutta l’area di studio e a diverse quote affiorano diffusamente depositi terrazzati marini pleistocenici a luoghi ricoperti da un sottile velo di sedimenti continentali recenti ed attuali. la storia quaternaria dell’area di capo vaticano ricalca dunque piuttosto fedelmente quella dell’intero arco calabro, con l’instaurarsi di un regime estensionale sin dal pliocene superiore, caratterizzato dalla presenza di numerose faglie normali sia parallele (ne-so) che perpendicolari (ono-ese) alla direzione generale dell’arco stesso (fig. 1). a partire dal pleistocene medio, i processi estensionali sono stati accompagnati da un forte sollevamento regionale, di cui i numerosi terrazzi marini sono il principale e più spettacolare effetto sul paesaggio costiero. lo schema tettonico sopra descritto per le zone in affioramento si estende probabilmente anche offshore, lungo il basamento sommerso del promontorio, come fig. 1 mappa sismotettonica dell’area di capo vaticano. la sismicità storica (quadrati neri) (217 bc–2002 ad, m≥5.5) è da cpti (gruppo di lavoro cpti, 2004); la sismicità strumentale (stelle nere) nel periodo 1981-2002 (m≤4) è da castello et al. (2004). i cerchi neri numerati da 1 a 4 indicano i diversi epicentri calcolati sulla base di dati macrosismici per l’evento del 1905 e proposti rispettivamente da 1) postpischl (1985); 2) camassi & stucchi (1997); 3) gruppo di lavoro cpti (2004), e sulla base di dati sismologici da 4) michelini et al. (2005). le strutture tettoniche principali (faglie da ‘a’ a ‘e’) sono da galadini et al. (2000), valensise & pantosti (2001), e tortorici et al. (2003). non c’è uniformità di vedute fra i vari autori sulla cinematica e/o sulla cronologia di tali strutture tettoniche. seismotectonic map of the capo vaticano area black squares indicate m≥5.5 historical earthquakes in the period 217 bc–2002 ad (gruppo di lavoro cpti, 2004) and black stars indicate (m≤4) instrumental seismicity between 1981 and 2002 (castello et al. 2004). black circles numbered 1 to 4 correspond to four different epicenters based on macroseismic data and suggested by 1) postpischl (1985); 2) camassi & stucchi (1997); 3) gruppo di lavoro cpti, (2004), and based on seismological data by 4) michelini et al. (2005). main tectonic structures (faults indicated by letters ‘a’ to ‘e’) are from galadini et al. (2000), valensise & pantosti (2001) and tortorici et al. (2003). authors do not fully agree about kinematics and chronology of these lineaments. suggerito da trincardi et al. (1987) e da argnani & trincardi (1988) sulla base di profili sismici e dati batimetrici. inoltre, chiocci & orlando (1996) descrivono terrazzi marini sommersi lungo la piattaforma continentale a 4-6 km dalla costa di briatico e vibo marina (fig. 1). l’area in studio risulta caratterizzata da una sismicità relativamente sparsa e poco frequente (fig. 1). se si eccettua il grande terremoto del 1905, per il quale vengono proposti quattro differenti epicentri a riprova della incertezza associata a tale evento, il catalogo parametrico dei terremoti italiani (cpti) riporta in zona solo un altro evento avvenuto nel 1928 (m=6, i=vii-viii) lungo il bordo meridionale del promontorio. altri terremoti storici, avvenuti fra il 1659 ed il 1783, pur avendo causato diffusi risentimenti nell’area studiata sono probabilmente ascrivibili all’attività di faglie localizzate nell’adiacente graben del mesima. similmente, la sismicità strumentale nel periodo 1981-2002 è caratterizzata da eventi isolati e di bassa magnitudo; anche in questo caso, le uniche sequenze sismiche registrate (comunque con m≤3.3) sono localizzate nella stessa area dell’evento storico del 1928. il terremoto dell’ 8 settembre 1905 il terremoto dell’ 8 settembre 1905, pur essendo uno dei più forti eventi della storia sismica italiana, resta scarsamente chiarito, soprattutto per quello che riguarda la definizione di una sorgente di riferimento. diversi furono gli studi coevi sul terremoto (i.e. baratta, 1906; mercalli, 1906; rizzo, 1907) che proposero ipotesi “sismogenetiche” legate alle conoscenze dell’epoca, mentre in tempi più recenti gli studi hanno riguardato maggiormente la distribuzione degli effetti dalla quale è stato ricavato un epicentro macrosismico (postpischl, 1985; camassi & stucchi, 1997; gruppo di lavoro cpti, 2004). l’unica magnitudo calcolata da dati strumentali conosciuta è di margottini et al., (1993) ms=7.5, mentre quella di derivazione macrosismica è maw=7.1 (gruppo di lavoro cpti, 2004). galli & bosi (2002) sono gli unici che hanno tentativamente associato un epicentro onshore dell’evento ad una struttura ben definita, la faglia di monte poro (faglia ‘e’ in fig. 1). il maremoto conseguente al terremoto è stato modellato da piatanesi & tinti (2002) su alcune faglie note in letteratura, senza risultati definitivamente attendibili. le due faglie, i cui parametri sono risultati i più vicini al modello numerico risultano quella di capo vaticano e quella di vibo valentia (faglie ‘a’ e ‘b’ in fig. 1), anche se la sorgente del maremoto, secondo gli autori andrebbe cercata più ad ovest. per raccogliere ulteriori elementi utili alla valutazione di ipotesi interpretative sulla sorgente del terremoto è stata avviata la revisione degli effetti dovuti all’evento. il piano quotato di partenza è quello presente sul cfti (boschi et al. 1995). scopo di questa parte del lavoro è stato quello di revisionare il piano quotato a partire dalle descrizioni degli effetti su fonti coeve all’evento, privilegiando i lavori tecnico-scientifici (baratta, 1906; mercalli, 1906; rizzo, 1907). in seconda istanza sono state consultate le cronache locali (cotroneo, 1906) e giornalistiche (malagodi, 1905) ed alcune storie locali (pugliese, 1996; kostner, 2002) pubblicate di recente. parte della ricerca è stata svolta sul posto al 91i terrazzi marini nell’area ... fine di recuperare materiali inediti, soprattutto di tipo iconografico e urbanistico (fig. 2). l’insieme delle informazioni raccolte, incrociato con una rilettura critica delle fonti, ha portato in diversi casi a modificare l’intensità proposta in boschi et al. (1995), soprattutto in zone maggiormente discoste dall’area più colpita, dove, per molte località, l’intensità al sito è risultata essere più contenuta. sono stati anche corretti errori di localizzazione di alcuni punti di intensità presenti in boschi et al. (1995). in particolare viene abbassata da x-xi a x l’intensità massima che viene assegnata a diverse località nell’area intorno a monteleone (attuale vibo valentia). gli effetti risultarono particolarmente distruttivi su molte piccole località site all’interno del promontorio, dove si concentrano quasi tutte le intensità più elevate. c’è da rilevare che in questa zona, diversamente che sulla costa, l’edilizia era particolarmente povera e quindi vulnerabile, come riscontrato direttamente su alcuni edifici superstiti e come già evidenziato da baratta (1906) all’epoca del terremoto. vi è inoltre da considerare la presenza di probabili effetti di sito che hanno aggravato l’impatto del terremoto, spesso in aree lontane dalla zona di massima intensità (a questo proposito vedi mercalli, 1906; mucciarelli, 2005). il riesame dei punti di intensità è stato effettuato allo scopo di poter utilizzare l’algoritmo boxer (gasperini et al. 1999) per il calcolo di localizzazione, dimensioni e orientamento della sorgente. lo stesso codice boxer usa, per il calcolo della magnitudo momento (mw), il metodo di gasperini & ferrari (1995), basato sulla relazione di wells & coopersmith (1994) per quanto riguarda l’ipotesi sulla dimensione della rottura. entrambe le procedure necessitano di un set di dati macrosismici il più affidabile possibile. poiché in linea di massima la distribuzione delle intensità più elevate è legata alle caratteristiche della sorgente, il calcolo dei parametri di faglia è stato effettuato usando i punti con i ≥ viii-ix, pienamente in accordo con quanto suggerito da gasperini et al. (1999). il risultato (fig. 3) ci mostra una struttura 36x14 km orientata circa n80° (±21°). la soluzione pone l’epicentro del terremoto a 38.68 n – 16.03 e, con mw pari a 6.8±0.2. la soluzione epicentrale è fortemente vincolata a terra dalla distribuzione dei punti di intensità, per cui non si può in questa fase escludere che l’origine del terremoto dell’8 settembre 1905 possa essere al largo della costa di capo vaticano. i terrazzi marini i terrazzi marini, visibili fino a quote di diverse centinaia di metri sul livello del mare nell’area di capo vaticano così come in gran parte del territorio calabrese, rappresentano la testimonianza fossile di antichi episodi di abrasione marina. queste forme del paesaggio, se datate, sono indicatori molto precisi dei tassi di deformazione verticale, poiché ogni terrazzo rappresenta la traccia di un dato regionale incisa nel paesaggio durante una risalita eustatica che culmina con un highstand (alto picco eustatico interglaciale). pertanto, se si riesce a datare uno o più terrazzi all’interno di una sequenza (assumendo che ogni paleolinea di riva sia associabile ad uno dei principali highstands della curva 92 f ig . 2 i n f ig u ra s o n o m o st ra ti a lc u n i e se m p i d e g li e ff e tt i d is a st ro si d e l t e rr e m o to s u lle lo c a lit à d e l v ib o n e se . l e im m a g in i, p re se d a l l ib ro d i p u g l ie s e (1 9 9 7 ), s o n o a n c h e r a p p re se n ta ti ve d e lle ti p o lo g ie e d ili zi e , m o lt o p o ve re , in u so a ll’ e p o c a n e lla z o n a d e l t e rr e m o to . a ) v ib o v a le n ti a ( e x m o n te le o n e ); b ) p is c o p io ; c ) z a m m a rò ; d ) p a rg h e lia . s o m e p h o to s ab o u t th e d is as tr o u s e ff e c ts o f th e e ar th q u ak e . in t h e p h o to s th e p o o r q u al it y o f b u ild in g s is c le ar ly v is ib le . a) v ib o v al e n ti a (e x m o n te le o n e ); b ) p is c o p io ; c ) z am m ar ò ; d ) p ar g h e lia . t h e p h o to s ar e f ro m t h e b o o k o f p u g l ie s e (1 9 9 7 ). l. cucci & a. tertulliani 93 f ig . 3 i n f ig u ra v ie n e m o st ra to i l se tt o re c e n tr a le d e l p ia n o q u o ta to d e l te rr e m o to d e ll’ 8 s e tt e m b re 1 9 0 5 . n e l ri q u a d ro è r ip o rt a to i l d e tt a g lio d e ll’ a re a d i m a ss im a i n te n si tà . l a s c a la d e lle in te n si tà è la s te ss a p e r le d u e f ig u re . il re tt a n g o lo v is ib ile in f ig u ra r a p p re se n ta la s o rg e n te d i r ife ri m e n to c o m e o tt e n u ta d a l p ro g ra m m a b o xe r (g a s p e r in i e t al ., 1 9 9 9 ). l a s te lla in d ic a l’ e p ic e n tr o c a lc o la to d a l m e d e si m o c o d ic e . p e r l’i n ve rs io n e s o n o s ta ti u sa ti i p u n ti d i i n te n si tà i ≥8 -9 . in te n si ty d at a m ap o f th e s e p te m b e r 8 , 1 9 0 5 e ar th q u ak e ; w e a ls o s h o w a z o o m o f th e e p ic e n tr al a re a. t h e i n te n si ty s c al e f o r th e t w o f ig u re s is t h e s am e . w e a ls o i n d ic at e t h e s o lu ti o n o f th e so u rc e m o d e l w it h a s o lid b o x, a n d t h e m ac ro se is m ic e p ic e n tr e w it h t h e b la c k st ar , b o th c o m p u te d b y th e b o xe r c o d e ( g a s p e r in i e t a l., 1 9 9 9 ). o n ly in te n si ti e s i≥ 8 -9 w e re u se d t o c o m p u te t h e so u rc e m o d e l. t h e s o lu ti o n s h o w n is o b vi o u sl y c o n st ra in e d b y th e in te n si ty d at a se t, t h at p ar ti al ly r e p re se n ts t h e a tt e n u at io n f ie ld o f th e e ve n t, e lo n g at e d o n t h e c o as t. i terrazzi marini nell’area ... 94 eustatica) è possibile ricostruire con grande accuratezza la storia dei sollevamenti della regione costiera in esame, nonché cercare di separare gli effetti del sollevamento regionale da quelli della deformazione locale imposta dalla vicinanza di faglie attive. i terrazzi di capo vaticano sono già stati investigati da alcuni autori, con risultati ed interpretazioni anche profondamente discordanti. a titolo di esempio, dumas et al. (1987) individuano almeno 25 paleolinee di riva pleistoceniche e suggeriscono che il sollevamento differenziale osservato nel settore settentrionale è in qualche modo connesso all’attività della faglia ‘b’ in figura 1. w e s t a w a y (1993) riconosce solo cinque terrazzi pleistocenici, sollevati uniformemente al tasso di 1 mm/anno e deformati ad un ulteriore tasso di 0,05 mm/anno dalla faglia ‘a’ (fig. 1). al contrario, miyauchi et al. (1994) descrivono almeno 12 ordini di terrazzi, sollevati a tassi oscillanti fra 0,3 e 1,0 mm/anno a causa dell’alternarsi di “doming uplift” e di “regional uplift”, che costituiscono anche l’unica causa di deformazione nell’area. infine, tortorici et al. (2003) riconoscono sei terrazzi completi (più una superficie superiore) e ricostruiscono, esclusivamente sulla base di datazioni tl, sollevamenti compresi fra 0,9 e 4,0 mm/anno, attribuendo la differenza tra questi due valori a deformazione tettonica locale, in gran parte lungo la faglia ‘e’ di fig. 1. nel presente lavoro, la ricostruzione dei terrazzi è stata ottenuta tramite interpretazione aerofotogrammetrica, analisi di carte topografiche alla scala 1:10.000, ed osservazioni di campagna; l’errore associato alle quote rilevate è di ±5 m. margini interni e superfici terrazzate così mappati sono stati correlati morfologicafig. 4 mappa dei margini interni e delle superfici terrazzate cartografati nell’area in studio in base alle foto aeree ed al rilevamento di campagna. i terrazzi sono numerati in ordine crescente di quota. l’attribuzione cronologica dei terrazzi è basata sulla correlazione con i picchi interglaciali della curva eustatica di waelbroeck et al. (2002). vengono anche riportati gli estremi a-b del profilo altimetrico di figura 5 e le tracce dei profili topografici 1 e 2 di figura 6. map of the marine terraces (#1 to #11, lowest to highest) that contour the study area; different colours are associated with the wavecut platforms and black thick lines mark the inner edges. the age of the terraces is based on the correlation with the interglacial peaks of the eustatic curve by waelbroeck et al. (2002). black segments marked by “1” and “2” indicate the traces of the topographic profiles in figure 5; letters “a” and “b” indicate the tips of the profile in figure 6. l. cucci & a. tertulliani mente, basandosi sulla continuità laterale dei terrazzi meglio conservati e sulla spaziatura verticale fra interfluvi adiacenti. questo processo ha portato all’identificazione di 11 terrazzi marini principali (ordinati da t1 a t11 per quote crescenti, fig. 4), con quote comprese fra 20 e 575 metri slm. le piattaforme di abrasione marina possono essere incise sia direttamente sul basamento metamorfico paleozoico, sia su depositi marini plio-pleistocenici. i depositi di terrazzo consistono in sabbie e arenarie marine a contenuto fossilifero quasi sempre scarso. le superfici terrazzate sono generalmente ben preservate (fig. 5); i margini interni ad esse associati, spesso chiaramente riconoscibili per chilometri, sono coperti localmente da un sottile strato di depositi colluviali. a causa di una più prolungata degradazione subaerea i terrazzi più alti e vecchi sono morfologicamente meno evidenti, mentre la superficie sommitale affiorante fino alla quota di ~700 metri appare più profondamente erosa e priva di margine interno. l’andamento delle quote dei margini interni dei terrazzi su un piano verticale parallelo alla linea di costa (fig. 6) è piuttosto variabile. è evidente un incremento delle altezze procedendo verso so, fino alla progressiva km 40 del profilo. il gradiente locale di sollevamento differenziale aumenta procedendo verso i terrazzi più antichi e sollevati, a testimonianza di un processo prolungato nel tempo e tuttora in atto, mentre il progressivo aumento del tasso di basculamento (rapporto fra gradiente locale ed età del singolo terrazzo) in senso inverso è indicativo di un aumento, seppur modesto, delle velocità di sollevamento. a sud di capo vaticano (km 40-45) i terrazzi raggiungono la massima altezza sul livello del mare, mentre il sollevamento differenziale si annulla. si osservano, inoltre, due zone con evidenti anomalie nell’andamento sub-orizzontale dei terrazzi, alle progressive km 18-23 e km 45-50. la ricostruzione della storia dei sollevamenti nell’area studiata si basa sulla revisione critica di una serie di datazioni disponibili in letteratura (vedi box in fig. 4). la datazione-correlazione chiave è quella di vibo marina, dove t3 è stato associato al picco dell’ultimo interglaciale (mis 5.5, ~124 ka), sulla base di una robusta convergenza di: a) la presenza di strombus bubonius nel deposito terrazzato (pata, 1947); b) due datazioni radiometriche u-th indipendenti effettuate su campioni di cladocora caespitosa da dumas et al. (1991) e da dai pra et al. (1993) con risultati omogenei (130.000 anni ± 8.000 e 121.000 anni ± 7.000, rispettivamente); c) una datazione aar su glycymeris che ha fornito un ratio di aminoacidi di 0,37±0,03 (dumas et al. 1989), in accordo con un’età dell’ultimo interglaciale. a conferma della correlazione t3-mis 5.5 c’è l’osservazione che all’highstand più pronunciato e prolungato nel tempo corrisponde il terrazzo morfologicamente più sviluppato e continuo della zona. sulla base delle evidenze citate la figura 7 suggerisce che la storia dei sollevamenti nell’area può essere tracciata a ritroso nel tempo fino a circa 600-700.000 anni fa, con la formazione e la successiva emersione dei due terrazzi superiori (t10 e t11), per i quali comunque esiste un margine di incertezza più ampio. per quanto riguarda la genesi della superficie sommitale, essa è presumibilmente di età siciliana inferiore (~1 ma) sulla base della presenza di globorotalia truncatulinoi95 fig. 5 profili topografici lungo due sezioni rappresentative dell’area in studio (vedi fig. 4 per la localizzazione delle sezioni). i segmenti più spessi marcano le superfici di terrazzo. la scala verticale è esagerata 3x. topographic profiles along two sections representative of the area (see fig. 4 for location of the sections). thicker lines mark the different terrace surfaces. vertical exaggeration of both profiles is 3x. i terrazzi marini nell’area ... des excelsa nei depositi ad essa associati (miyauchi et al. 1994). pur mancando evidenze di brusche variazioni nei tassi di sollevamento calcolati per ogni intervallo di tempo fra due terrazzi consecutivi, tale processo sembra in lieve ma progressivo aumento nel tempo, con velocità medie che passano da ~0,79 mm/anno (calcolate nel periodo 0,7-0,5 ma) a ~0,93 mm/anno (a partire dal picco dell’ultimo interglaciale). in particolare, i valori illustrati in figura 7 sono riferiti alla zona di capo vaticano, dove le paleolinee di riva raggiungono le massime quote nell’area in studio e dove la sequenza di terrazzi è presente quasi al completo. più in generale, lo studio dei terrazzi marini in quest’area mette in luce un inizio del processo di sollevamento a 0.7-1.0 ma e velocità medie leggermente inferiori a 1 mm/anno. tali caratteristiche sono pienamente confrontabili con quelle osservate lungo i ~200 km di arco calabro che vanno dalla piana di sibari a nord all stretto di messina a sud (vedi, fra gli altri: westaway, 1993; bordoni & valensise, 1998; cucci, 2004; ferranti et al. 2006). a sud di capo vaticano (fra le progressive km 45 e 50 di fig. 4) le paleolinee di riva sono intersecate da una struttura tettonica ad andamento ono-ese (faglia ‘e’ in fig. 1, “coccorino fault” o “calimera fault” auct). lo stato di attività di questa faglia è piuttosto dibattuto fra gli autori, dato che alcuni la ritengono tuttora attiva dal pleistocene superiore (m i c h e t t i et al. 2000; tortorici et al. 2003), altri le attribuiscono una generica attività durante il quaternario (ambrosetti et al. 1987; miyauchi et al. 1994), mentre dumas et al. (1987), 96 fig. 6 andamento altimetrico delle linee di riva lungo una sezione parallela alla costa. i colori corrispondono a quelli di figura 4. elevation profile of inner edges (black thick lines) and wavecut platforms (coloured areas, same colors of fig. 4) along a vertical section parallel to the coast. fig. 7 il grafico mette in relazione il sollevamento netto delle paleolinee di riva a capo vaticano (quota di osservazione corretta per il paleolivello del mare all’epoca della formazione) con l’età corrispondente desunta dalla curva eustatica di waelbroeck et al. (2002). vengono anche indicati i tassi di sollevamento calcolati per ogni intervallo di tempo fra due terrazzi consecutivi. relation between the net uplift of the paleoshorelines at capo vaticano, calculated as the observed elevation corrected for the altitude of the paleosea-level, and the corresponding ages from the sea-level curve by waelbroeck et al. (2002). figures indicate calculated uplift rates between adjacent couples of terraces. l. cucci & a. tertulliani galadini et al. (2000) e valensise & pantosti (2001) la considerano inattiva o non la riconoscono. a tale struttura è comunque associata una evidente scarpata morfologica di una decina di chilometri di lunghezza, la cui continuazione offshore per un tratto almeno altrettanto lungo è molto probabile dall’osservazione della batimetria (argnani & trincardi, 1988). le paleolinee di riva appaiono chiaramente dislocate e la valutazione dell’entità delle dislocazioni permette di ricavare informazioni sull’attività di questa faglia. in figura 8 evidenziamo la separazione verticale osservata sui quattro terrazzi inferiori con i corrispondenti tassi verticali medi a lungo termine attraverso la struttura tettonica, che oscillano fra 0,12 mm/anno e 0,16 mm/anno. tassi verticali su periodi più brevi possono essere desunti dalla dislocazione netta calcolata su ogni coppia di paleolinee consecutive; gli slip rates verticali così ottenuti variano tra 0,04÷0,06 mm/anno (fra il mis 9.3 ed il mis 5.5 – da 330 ka a 124 ka) e 0,21÷0,25 mm/anno (fra il mis 5.5 ed il mis 5.1 – da 124 ka a 80 ka). discussione l’applicazione del codice boxer (gasperini et al. 1999) al campo macrosismico revisionato del terremoto del 1905 mostra come la più probabile struttura sismogenetica responsabile dell’evento possa essere una faglia di dimensioni 36x14 km e direzione ~80º. parallelamente, abbiamo anche visto come le variazioni altimetriche osservate lungo le paleolinee di riva attraverso la faglia ‘e’, la cui direzione è invece circa 100°, abbiano permesso di confermare che tale struttura è attiva. per verificare quanto ognuna di queste due strutture sia congruente con gli elementi geologici, topografici e macrosismici a disposizione, abbiamo calcolato e posto a confronto il campo di deformazione indotto in superficie dall’azione della faglia ottenuta da boxer (faglia “macrosismica”) rispetto a quello della faglia osservata in campagna (faglia “geologica”). la modellazione, basata sulla teoria della dislocazione elastica ed eseguita con il codice ‘faultstudio’ (basili, 2005) assume uno slip uniforme su faglie piane e rettangolari in un semi-spazio elastico (okada, 1985). geometria e dimensioni delle due strutture sono vincolate in un caso dall’output del programma boxer per la faglia “macrosismica”, nell’altro dalle evidenze morfologiche e batimetriche già descritte, oltre che dall’alto valore di magnitudo associato all’evento del 1905. la figura 9 mostra qualitativamente i risultati di questo test applicato a quattro differenti ipotetiche sorgenti sismogenetiche secondo il seguente criterio: una coppia di strutture tipo “macrosismica”, in cui rimanendo costanti tutti gli altri parametri viene fatta variare solo la vergenza della 97 fig. 8 in questo ingrandimento fra le progressive km 43 e 53 di figura 4 evidenziamo la dislocazione verticale delle quattro paleolinee di riva inferiori attraverso la faglia ‘e’. vengono anche indicati i corrispondenti tassi verticali medi a lungo termine attraverso la struttura tettonica, che oscillano fra 0,12 mm/anno e 0,16 mm/anno. this zoom between km 43 and 53 of figure 4 shows the vertical separation evidenced along the four lower paleoshorelines across fault ‘e’. long-term vertical slip rates across this structure range between 0.12 and 0.16 mm/yr. i terrazzi marini nell’area ... 98 f ig . 9 v a ri a zi o n i a lt im e tr ic h e p re vi st e d a m o d e lla zi o n i d i f a g lie p ia n e e r e tt a n g o la ri in u n s e m isp a zi o e la st ic o . p e r o g n i m o d e lla zi o n e r ip o rt ia m o la z o n a d i m a ss im o s o lle va m e n to e s u b si d e n za a sp e tt a ti ( e sp re ss i c o m e f ra zi o n e d e llo s lip u n it a ri o ), o lt re a lla p ro ie zi o n e v e rt ic a le d e l p ia n o d i f a g lia e d a lla s u a in te rs e zi o n e c o n la s u p e rf ic ie . m o d e lli n g o f e xp e c te d v e rt ic al d is p la c e m e n t (e xp re ss e d a s a fr ac ti o n o f th e u n it ar y sl ip ) al o n g p la n ar f au lt s e m b e d d e d i n a n e la st ic h al fsp ac e . w e a ls o s h o w t h e c u to ff l in e o f th e u p -d ip p ro je c ti o n o f th e m o d e l f au lt a n d it s su rf ac e p ro je c ti o n . l. cucci & a. tertulliani faglia (60° verso nno o verso sse, rispettivamente), dato che il programma “boxer” non fornisce informazioni al riguardo; una coppia di strutture tipo “geologica” in cui, rimanendo costanti tutti gli altri parametri, viene fatta variare solo la cinematica della faglia (normale pura in un caso, transtensiva sinistra nell’altro). per ogni modellazione la figura riporta la zona di massimo sollevamento e subsidenza aspettati (espressi come frazione dello slip unitario), oltre alla proiezione verticale del piano di faglia ed alla sua intersezione con la superficie. le due modellazioni relative alla faglia “boxer” forniscono indicazioni piuttosto discordanti. infatti, il campo di deformazione associato alla faglia nord-vergente interessa marginalmente l’area di massima intensità, mentre la soluzione con il piano di faglia sud-vergente è quella che meglio circoscrive all’interno dell’area a massimo gradiente di deformazione aspettato i punti di maggiore intensità osservate. inoltre, la soluzione con la faglia sud-vergente è quella che meglio giustifica la generazione di un maremoto, dato che produrrebbe deformazioni verticali apprezzabili nell’area che è stata effettivamente interessata dall’azione dello tsunami associato all’evento del 1905 (vedi anche piatanesi & tinti, 2002). d’altro canto, nessuna delle due soluzioni “boxer” sembra essere in accordo con le evidenze topografiche e/o geomorfologiche, dato che le aree di depressione allungata che esse produrrebbero non hanno riscontro con l’andamento reale della topografia, né tantomeno con l’andamento delle quote dei terrazzi marini. le due modellazioni ottenute con la faglia “geologica” forniscono indicazioni piu’ omogenee. la soluzione con rake = 270º (faglia normale pura) produrrebbe un gradiente di deformazione simmetrico trasversalmente al piano di faglia, con una depressione piuttosto pronunciata al margine settentrionale della piana di gioia tauro ed un più modesto sollevamento nella dorsale di monte poro. questa soluzione conferma inoltre un elevato accordo fra campo di deformazione previsto ed andamento delle quote delle linee di riva, che verrebbero cosismicamente sollevate soprattutto nei dintorni di capo vaticano e subirebbero una vistosa subsidenza spostandosi verso sud fino a nicotera. la soluzione con rake = 315º (faglia normale con componente trascorrente sinistra) ricalca sostanzialmente quella appena descritta, all’infuori di un gradiente di deformazione leggermente meno ‘piccato’ nei valori assoluti e di un’area di massima subsidenza spostata in mare aperto, che però non ne modifica qualitativamente il confronto con le evidenze topografiche e geomorfologiche. entrambe le soluzioni, infine, mostrano un accordo solo parziale con i dati macrosismici a disposizione, mentre produrrebbero deformazioni verticali vistose nell’area interessata dallo tsunami del 1905. i dati geologici e macrosismici presentati in questo lavoro, nonché il loro confronto con le elaborazioni provenienti dalle modellazioni di sorgenti sismogenetiche, forniscono una serie di evidenze ed offrono lo spunto per la discussione di un numero di questioni ancora aperte. le evidenze sono: a) sono stati riconosciuti undici terrazzi marini principali; b) l’area di capo vaticano è in sollevamento attivo da almeno 700.000 anni, a velocità medie leggermente inferiori a ~1 mm/anno; c) il processo di sollevamento sembra in lieve ma progressivo aumento nel tempo, con velocità medie che passano da ~0,79 mm/anno (fra 0,7 e 0,5 ma) a ~0,93 mm/anno (ultimi 124 kyr); d) è evidente un fenomeno di tilting di terrazzi, con altezze delle paleolinee di riva progressivamente minori procedendo lungo la costa da sud (capo vaticano) verso nord (pizzo). il tilting diviene trascurabile a sud di capo vaticano; e) le variazioni di quota osservate nelle paleolinee di riva a cavallo della faglia ‘e’ indicano che tale struttura è attiva da almeno 330.000 anni; f) i tassi verticali medi sulla faglia ‘e’ variano negli ultimi 215.000 anni fra 0,12 e 0,16 mm/anno. ci sono evidenze di tassi verticali maggiori (fino a 0,25 mm/anno) relativi a periodi più brevi; g) il piano quotato rivisitato del terremoto del 1905 conferma che le massime intensità sono state raggiunte in un’area estesa fra vibo valentia e capo vaticano; h) la magnitudo macrosismica (m=6.8) conferma l’importanza dell’evento in termini energetici. le evidenze appena descritte possono altresì fornire un contributo importante nell’approccio della questione fondamentale riguardante il rapporto fra l’evento del 1905, la sua sorgente, e le faglie sismogenetiche nell’area. abbiamo visto che i terrazzi marini forniscono una chiara indicazione sullo stato di attività recente della faglia ‘e’, anche se è probabile che tale struttura non sia l’unica attiva nell’area; abbiamo anche constatato come la faglia ‘e’, indipendentemente dal tipo di cinematica imposta (normale pura o con componente trascorrente), sia pienamente compatibile con la magnitudo dell’evento del 1905 (ed indirettamente anche con il dato di magnitudo ottenuto per via macrosismica), e produca deformazioni verticali vistose nell’area interessata dall’azione dello tsunami associato all’evento stesso. se si considera che la modellazione del dato macrosismico fornisce indicazioni vincolanti soprattutto per le dimensioni della sorgente e che il più recente lavoro di rilocalizzazione del terremoto del 1905 ne colloca l’epicentro a mare (sebbene con un certo margine di errore) ad una ventina di chilometri ad ovest di capo vaticano (michelini et al. 2005), allora anche l’apparente scarso accordo fra deformazione teorica prodotta dalla faglia e campo macrosismico reale prodotto dal terremoto potrebbe assumere un significato diverso. in questo caso l’epicentro di michelini et al. (2005) potrebbe corrispondere alla nucleazione unilaterale lungo una struttura ad elevata direttività, così da giustificare da un lato la sostanziale omogeneità nelle intensità osservate in tutto il promontorio di capo vaticano data la notevole distanza dall’epicentro, e dall’altro l’evidente decremento delle intensità registrate nella piana di gioia tauro. in questo caso tale faglia agirebbe, con una possibile cinematica transtensiva, come lineamento regionale trasversale di trasferimento della deformazione estensionale fra le già citate strutture ad andamento ne-so nell’offshore tirrenico e quelle, con il medesimo andamento, riportate nella piana di gioia tauro (valensise & pantosti, 2001; galli & bosi, 2002). in conclusione, l’analisi di dati geologici evidenziati dai terrazzi marini ed il confronto con lo scenario del terremoto desunto dalle osservazioni macrosismiche hanno permesso la ricostruzione della storia dei sollevamenti nell’area di capo vaticano e la formulazione di alcune ipotesi riguardanti geometria e cinematica della sorgente del terremoto del 1905. pur nella consa99i terrazzi marini nell’area ... pevolezza che esistano soluzioni alternative, ed auspicando una più cospicua mole di dati di tipo strutturale soprattutto nell’offshore tirrenico, la soluzione proposta indica una struttura con una chiara espressione morfologica e batimetrica, con una attività recente ed attuale testimoniata dalla geologia e dalla microsismicità, in un quadro nel quale la deformazione tettonica locale associata a sorgenti sismogenetiche rimane comunque quasi un ordine di grandezza inferiore al sollevamento regionale. ringraziamenti desideriamo ringraziare i due referees anonimi per i commenti e i preziosi suggerimenti che hanno contribuito a migliorare l’articolo. questo lavoro è stato finanziato nell’ambito della convenzione dpc-ingv, progetto s2: “valutazione del potenziale sismogenetico e probabilità dei forti terremoti in italia”. bibliografia aïfa t., feinberg h. & pozzi j.p. 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(1993) quaternary uplift of southern italy, j. geophys. res., 98, 21741-21772. 101 ms. ricevuto il 16 maggio 2006 testo definitivo ricevuto il 10 ottobre 2006 ms. received: may 16, 2006 final text received: october 10, 2006 i terrazzi marini nell’area ... imp.bertoldi& new data from northern apennines (italy) pollen sequences spanning the last 30,000 yrs remo bertoldi 1, alessandro chelli 2, rachele roma 1 & claudio tellini 2* 1 dipartimento di biologia evolutiva e funzionale, università degli studi di parma, parma, italy 2 dipartimento di scienze della terra, università degli studi di parma, parma, italy * corresponding author: c. tellini, dipartimento di scienze della terra, università di parma, viale g. usberti, 157/a, 43100 parma, italy. e-mail: claudio.tellini@unipr.it abstract: bertoldi r., chelli a., roma r. & tellini c., new data from northern apennines (italy) pollen sequences spanning the last 30,000 yrs. (it issn 0394-3356, 2007). palynological analyses and radiocarbon dates were performed on lacustrine sequences from the two sites of berceto (820 m a.s.l.) and lagdei (1,254 m a.s.l.) in parma province (northern italy). this work allowed us to obtain new data and constrains about vegetational and climatic history of the northern apennines from upper pleistocene to lower holocene. the berceto core provided a long pollen sequence from the pleniglacial to the lateglacial. in it the oscillations of the percentage of picea and of the concentration values of ap, allow us to highlight a succession of stadials and interstadials. the correlation among three climatic amelioration periods found in the berceto pollen sequence and the interstadials tursac, laugerie and lauscaux was discussed. the lagdei lacustrine sequence, already studied by one of us in the 1980, was newly cored and analyzed in its portion tributable to the lateglacial and postglacial. the results from pollen analyses and radiocarbon dates allowed us to establish that bertoldi interpretation, questioned by lowe, was correct and to reconstruct the vegetation characters at the lateglacial/postglacial boundary for the northern apennines. riassunto: bertoldi r., chelli a., roma r. & tellini c., nuovi dati da sequenze polliniche degli ultimi 30.000 anni nell’appennino settentrionale (italia). (it issn 0394-3356, 2007). sono state condotte analisi palinologiche, corredate da datazioni assolute 14c, in due depositi lacustri dell’appennino parmense nell’ambito di più vaste ricerche glaciologiche-geomorfologiche in questo settore dell’appennino settentrionale. scopo di questo lavoro è la ricostruzione della storia vegetazionale e climatica dell’appennino settentrionale nell’intervallo pleistocene superiore – olocene inferiore che finora appare ancora ampiamente lacunosa. infatti mentre sono numerosi gli studi pollinici in piccole conche palustro-lacustri di età olocenica, soltanto due profili pollinici (lagdei e prato spilla) svelano episodi di età tardoglaciale. nessun dato pollinico e/o cronologico è invece disponibile finora per il pleniglaciale. la successione lacustre del deposito di berceto (820 m s.l.m.) ha fornito una lunga sequenza pollinica appartenente al pleniglaciale ed in parte al tardoglaciale. questa successione vegetazionale è troncata alla sommità da una grossa lacuna sedimentaria che delimita alcuni eventi riferibili al postglaciale inferiore. la sequenza pollinica pleniglaciale permette di intravedere episodi stadiali e interstadiali, sulla base delle oscillazioni dei valori percentuali di picea e dei valori delle concentrazioni ap. le fasi stadiali sono caratterizzate da formazioni steppiche con pinus, mentre quelle interstadiali da formazioni aperte a pinus con presenza di picea. tentativamente le tre fasi di miglioramento climatico del pleniglaciale sono correlate (messe in relazione) con gli interstadiali di tursac, laugerie e lauscaux. il limite pleniglaciale/tardoglaciale sembra chiaramente espresso ed appare un po’ più antico di 14.480 ± 50 14c bp. la sequenza tardoglaciale di berceto è troncata al livello di m 6,20 datato 11.150 ± 70 14c bp. il deposito lacustre di lagdei, alta val parma (1254 m s.l.m.), già studiato nel 1980 da uno di noi, ma allora non corredato da datazioni assolute, è stato nuovamente sondato e studiato nella sua porzione tardoglaciale e postglaciale (lagdei-ii) con il supporto di datazioni radiometriche. scopo principale era quello di individuare nella sequenza il limite tardoglaciale /postglaciale e quindi di ordinare nel tempo gli eventi vegetazionali del tardoglaciale, che erano stati contestati e reinterpretati da lowe. i risultati pollinici e cronologici della sequenza di lagdei-ii confermano in pieno l’originaria interpretazione della sequenza pollinica fatta da bertoldi nel 1980. in particolare è stato stabilito definitivamente il limite tardoglaciale/postglaciale al limite tra le z.p. c e d, limite che coincide con il passaggio fra sedimenti inorganici ed organici e che risulta collocato 15/20 cm sotto al livello datato 9.900 ± 80 14c bp. e’ stato così possibile seguire nel tempo l’evoluzione vegetazionale stadiale/interstadiale durante l’intero tardoglaciale nell’appennino settentrionale. keywords: pleniglacial, lateglacial, palynology, palaeoclimate, italy. parole chiave: : pleniglaciale, tardoglaciale, palinologia, paleoclima, italia. il quaternario italian journal of quaternary sciences 20(1), 2007 3-20 1. introduction the sector of the northern apennines (northern italy) among liguria, emilia and tuscany is between 45° 05’n and 43° 30’n and between 8° 39’e and 12° 22’e. it reaches the maximum altitude in correspondence of mt. cimone (2,165 m) (fig. 1). severe geomorphological processes acted in the northern apennines in the late quaternary, during which at least two glacial episodes occurred (losacco, 1949; federici, 1977). glacial landforms (i.e.: cirques, troughs, moraines) and deposits (i.e.: till and lacustrine sequences) are well represented in several areas, such as in the parma and enza valleys, at elevations ranging from 750 to 1,800 m a.s.l. many palustrine and lacustrine deposits in this area were extensively studied by means of pollen analyses, in order to reconstruct the vegetational history and environmental changes which occurred. unfortunately, only occasionally the pollen analyses were supported by radiocarbon datings (chiarugi, 1936; ferrarini, 1962; braggio morucchio et al., 1978; 4 r. bertoldi et al. figure 1 geographic sketch map of the area (a) and of the sites considered in the text (b). inquadramento geografico dell’area (a) e delle località considerate nel testo (b). bertoldi, 1980; gentile et al., 1988; cruise, 1990; lowe, 1992; lowe & watson 1993; montanari et al., 1994; watson, 1996), and only for two sequences,(1) at lagdei, in the parma valley (bertoldi, 1980) and (2) at prato spilla, in the enza valley (lowe, 1992) (fig.1) was demonstrated a lateglacial age (no more than 13,000 14c yr bp) for the deepest parts of the deposits. in reality, at lagdei a pollen record was detected that can be confidently referred to early upper pleistocene (bertoldi, 1980), but the lack of radiocarbon datings did not allow its sure chronological attribution. at present, no pollen sequences and/or radiocarbon datings are available in this area for the pleniglacial. therefore, one of the problems in the palaeoenvironmental studies in the northern apennines, is the lack of palaeoclimatic records corresponding to the time interval from the last glacial maximum to lateglacial, a crucial time for the environmental changes. in this paper we present the results of pollen analyses and radiocarbon datings performed on a lacustrine sequence found in correspondence to the berceto village (parma province), located not far from the site of lagdei, containing the lgm and the transition to the lateglacial. moreover, we present a new pollen diagram from the sequence of the lagdei site, this time supported by radiocarbon datings. on the whole, the pollen data and radiocarbon dates from the two sequences allow us to illustrate, for the first time, the vegetational and floristic features of the pleniglacial in the northern apennines and to investigate the boundary pleniglacial/lateglacial. moreover, more detailed issues are provided on the vegetational and climatic events that took place during the lateglacial-early postglacial time. 2. the studied sites 2.1 the berceto site the berceto village lies at 820 m a.s.l., close to the divide between the baganza torrent and manubiola torrent, the latter a tributary of the taro river (fig. 1). the geological setting of the berceto area, where three different ligurian tectonic units outcrop (servizio geol. it., 2002), is characterized by a south-verging recumbent anticline that develops within sandstones (arenarie di scabiazza formation). the rocks underlying the sandstones are mainly shaly rocks (argille a palombini di monte rizzone formation and the so-called complesso ofiolitico) (bertoldi et al., 2004). berceto is at the top of a westward-trending slope that experienced many landslide events of different types and sizes. a shallow hollow, lengthened nnessw and with an extension of about 30x103 m2, is in the area between the village and the divide. it is the morphological expression of the trench linked to a rotational landslide that involves the large part of the top of the berceto slope. 2.2 lithostratigraphy of the berceto core the lacustrine sequence found in berceto is 25 meters long and represents about 50% of the total length of a core (fig. 2) collected from a borehole drilled in the centre of the trench due to the landslide. lithostratigraphic analyses were performed on the 5new data from northern apennines ... deposit. in particular, optical microscopy on polished thin-sections yielded information on the sediments fabric and structure; petrographic and mineralogical investigations were also accomplished by means of sem analyses. here we present the main highlights on the berceto sequence and the more exhaustive description is available in bertoldi et al. (2004). the sequence represents the infill of the landslide trench and, from the bottom to the top, the sequence was subdivided into 6 lithological units. the borehole encountered the bedrock at the depth of 48.00 m, represented by argille a palombini di monte rizzone, while from 48.00 to 31.00 m (unit 6, fig. 2) a breccia made up of clasts with silty matrix appeared. the first unit of the lacustrine sequence extends from 31.00 to 17.00 m depth (unit 5, fig. 2). generally, it is composed by light grey silty graded laminae, from 1 to 3 mm thick, and submillimetric dark clayey organic laminae. in detail, the graded laminae are fining upward and show a grey-yellowish lower portion gradually changing pale grey. sometimes, whitish (pale) very thin laminae are put together with the clayey dark organic ones. the pale laminae contain dolomite and mixed layers of clay minerals (illite/smectite). the laminae are folded and affected by shear surfaces. the clastic graded laminae are short repeated sedimentary events. they may represent either flows which occurred from the banks of the lake or the sediment influx from its catchment area. in reality, the lake did not have a tributary but the main source for the water was, likely, the surface runoff that occurred in its surrounding area. the dark and pale laminae were produced by precipitation and flocculation of clay-rich material, during periods characterized by the lack of coarse clastic inputs. between 17.00 and 9.20 m depth (unit 4, fig. 2) a grey-yellowish silt exists that contains levels with pale and dark laminae, deformed in a ductile way and, locally, very fine sands with scattered plant scraps and wood fragments appear. the pale and dark laminae are vague, even if they are still visible. from 9.20 to 6.10 m depth (unit 3, fig. 2), a massive package occurs of light grey fine silty sand. there are intraclasts that vary in colour from lightto dark grey and, locally (especially between 9.20 m and 9.12 m depth), thin levels with plant remains. within this unit the deformation is high, the formerly laminated structures are almost completely destroyed and the material is rather homogeneous. in general, as stated by bertoldi et al. (2004), the whole lacustrine sequence shows, from the bottom to the top, a rising deformation linked to small shackings, as testified by the coherence of the sequence, due to the landslide movements. the features of different units show that the landslide events occurred after the deposition of the unit 5 and they were recorded by each unit in different ways, probably regarding their depth below the bottom of the ancient lake. in the units 4 and 3 the events occurred just after their deposition, when they were still very close to the bottom of the lake and to the water, whereas the unit 5 was affected by folding and shearing when it was already covered by overlying sediments and far from the water. the unit 2 (fig. 2) from 6.10 to 4.30 m depth, 6 represents the definitive infill of the berceto lacustrine basin. the unit starts with a thin layer of sand, gradually replaced upwards by a thick layer of poorly preserved peat, as emphasized by the content of sporomorph that is dominated by oxidized and broken specimens. the bad conservation of peat suggests that it underwent events of pervasive reworking. from 4.30 m depth to 0 m (unit 1, fig. 2) a chaotic breccia made up of poligenic clasts (limestones, sandstones, ophiolithes, etc.) of different sizes and a silty-clay matrix exists. 2.3 the lagdei site: features and previous works the lagdei site is located in the high parma valley at about 1,254 m a.s.l., 12 km south of berceto (fig. 1). around the lagdei site, a mainly arenaceous succession (macigno formation, tuscan nappe) that is made up of thick to very thick turbiditic units, is widely exposed. from a geomorphological point of view, relict glacial landforms and deposits prevail. the evolution of the confluent parma valley glacier, after its maximum in correspondence of the lgm (equilibrium line altitude-ela 1,260 m a.s.l. and glacier front at 730 m a.s.l.), was the topic of an article written by federici & tellini (1983). they recognized at least three stages during the retreat of the glacier. the ela of the first stage reached about 1,370 m a.s.l., with an increase of about 110 metres as regards the lgm. in correspondence of the second stage (ela 1,530 m a.s.l.) the parma valley was characterized by three distinct glaciers, each one confined within one of the three main deep valleys representing the high parma torrent basin. at that time, the overdeepened hollow of lagdei was free from the ice and the sediment deposition started. during the third stage, the ela exceeded the medium altitude of the divide of the northern apennines and only very small glaciers were within the cirques or snowfields which existed on the slopes with a northern aspect. federici & tellini (1983) correlated, by means of the increases of the equilibrium line altitude (ela), the glacial stages of the parma valley with the classic ones of the alps and they put the third stage in correspondence to the younger dryas. nowadays, a marsh in the middle of the lagdei site exists and it represents the closure of the deposit that filled the overdeepened glacial hollow. pollen analyses on the lagdei sequence began in the early 1980s, when a 12.60 m borehole was handdrilled in the centre of the deposit and analyzed for its pollen contents (bertoldi, 1980). the pollen record indicates that the upper segment (i.e., from the top of the core down to 8.80 m depth) represents the holocene. a good correlation was found between this interval and the coeval pollen records previously identified in the northern apennines (chiarugi, 1936; ferrarini, 1962; braggio morucchio et al., 1978). also the middle part of the core (between 9.85 and 8.80 m depth) provided a well preserved pollen record. because of the lack of radiocarbon datings, the chronostratigraphic interpretation of this interval was achieved by comparison with the better age-constrained vegetational sequences from the southern alps (zoller, 1960; beug, 1964; sercelj, 1966; bertoldi, 1968; beaulieu de & jorda, 1977; behre, 1967; schneider, 1978), which suggested that the middle part of the lagdei sequence is lateglacial in age. this finding was especially important, because for the first time a complete pollen record straddling the lateglacial was found in the northern apennines. in the basal portion of the core (from 12.60 to 10.00 m depth), further vegetational events were recognized, but their age still remains unkfigure 2 lithological features of berceto and lagdei-ii boreholes. litostratigrafia dei carotaggi di berceto e di lagdei-ii. r. bertoldi et al. 7 nown. a new core (“lagdei-ii” core hereafter) was recovered in 1994 with the specific purpose of collecting material suitable for radiocarbon datings, thus providing better age control for the lagdei pollen record. the lagdei-ii borehole was drilled at the southern margin of the lagdei lacustrine area. a continuous and undisturbed core, approx. 15.00 m long, was recovered and can be subdivided into 7 lithostratigraphic units (fig. 2) that are synthetically described. from the top to the bottom of the sequence, after 0.90 m of reworked filling there are: the unit between 0.90 and 2.40 m depth: an alluvial fan deposit characterized by gravels with silty-sandy matrix. the unit between 2.40 and 6.70 m depth: represented by a well-preserved peat layer that contains a fine sandy inorganic fraction. from 6.70 to 7.00 m depth: grey to greenish sandy silt. the unit between 7.00 and 7.30 m depth: made of medium to coarse silty sand, that ranges in color from grey to greenish. from 7.30 to 8.30 m depth: yellowish sandy silt with layers made of silty sand. the unit from 8.30 m to the bottom of the core: a diamict made of clasts of variable size and a sandy-silty matrix. this unit is interpreted as a lodgement till left from the glacial tongue on the bottom of the overdeepened hollow. 3. materials and methods in order to perform pollen analysis, we collected 65 samples from the berceto core, in the interval between 4.30 and 30.00 m, and 70 samples from the lagdei core, in the interval between 2.50 and 8.50 m. peaty samples were prepared according to the techniques described by faegri & iversen and acetolysis (erdtman’s) procedures. sediment samples with prevailing inorganic content were treated according to standard laboratory protocols (zheng, 1986, modified): 10 grams of dried sediments, washing with hcl, soaking in hf, lüber tecnique, boiling in diluited 10% koh, followed by enrichment procedure, in particular gravitative separation using zncl2 (density 2,004 g/cm 3) and sonication. during the first step of chemical treatment, a tablet containing a determined number of lycopodium spores was added to each sample in order to estimate the pollen concentration (stockmarr, 1971). an average of 400 pollen grains per sample were counted. the pollen flora is represented in analytical pollen diagrams (figs. 3-5). the pollen curves show the role and development of single taxa, both of the arboreal (ap) and herbaceous plants (nap). interpretation of the vegetational development is based on summary pollen diagrams, in which percentage curves either of selected pollen taxa (such as betula, picea, abies, fagus) or pollen groups are shown. specifically, these are: pinus-group: mainly pinus + other pioneering taxa, such as juniperus and hippophae; quercetum: mainly quercus, secondly corylus, ulmus, tilia, being acer, carpinus, ostrya and ilex sporadic; other ap: principally alnus, salix, cf. populus; artemisia-group: mainly artemisia + ephedra; other nap: in decreasing order of abundance, these are asteraceae, poaceae, caryophyllaceae, chenopodiaceae, cistaceae (helianthemum included), ranunculaceae ( thalictrum included), brassicaceae, polygonaceae, fabaceae, plantaginaceae and other sporadic herbaceous taxa. hygro-hydrophytes are also included in this group, because their presence is persistently low and discontinuous. on the right side of the pollen diagrams, the ap concentration curve is represented. 4. results 4.1 berceto sequence pollen flora taxonomic details are shown in the analytical pollen percentage diagram (fig. 3). the ap are ever prevalent. in detail, in the middle-lower portion of the diagram pine (mainly pinus sylvestris-type and traces of p. mugo-type) clearly prevails accompanied by low values of picea, juniperus, hippophae, while broad-leaved trees (as quercus, betula, ulmus, tilia, carpinus, corylus, etc.) are sporadic. these last taxa with abies become significant only in the final spectra of the profile. the nap are represented continuously by ephedra (e. distachya-type and e. fragilis-type), artemisia and other asteraceae, chenopodiaceae, poaceae. open curves show ranunculaceae with thalictrum, brassicaceae, fabaceae, polygonaceae, plantaginaceae, rubiaceae, rosaceae, and traces of other nap, as dipsacaceae, ericaceae, gentianaceae, etc. the hygro-hydrophyta (cyperaceae, sparganiaceae, typhaceae, nymphaeaceae, myriophyllum) are very scarce. biostratigraphy the berceto summary pollen sequence (fig. 4) can be subdivided into three major segments. the basal segment is rather long, from 30.00 to 12.50 m depth, and characterized by a rather homogeneous pollen flora. specifically, pinus-group is dominant (percentages 80%-90% of the pollen sum) with relatively abundant picea, other ap occur sporadically, while the nap groups are largely subdued. further subdivisions of these segments in local pollen assemblage zones (paz) can be established based on the oscillations either of picea percentages or ap concentrations. indeed, paz ber-2, ber-4, ber-6 and ber-8 show relative high percentages of picea and appreciable ap concentrations (in excess of 5,000 grains/g); in contrast, paz ber-1, ber-3, ber5 and ber-7 are characterized by negligible values of picea and low ap concentrations (around 2,500 grains/g). the middle segment of the sequence, between 12.50 and 6.20 m depth, is characterized by two successive events of major increases in the nap complex, which simultaneously result in the two abrupt decreases in the pinus-group. new data from northern apennines ... 8 f ig u re 3 a n a ly ti c a l p o lle n p e rc e n ta g e d ia g ra m o f b e rc e to . p e rc e n ta g e s re fe r to t h e p o lle n s u m ( a p + n a p ). d ia g ra m m a p o ll in ic o a n a li ti c o d i b e rc e to . l e p e rc e n tu al i si r if e ri sc o n o a l c o n te g g io t o ta le d e i p o lli n i ( a p + n a p ). r. bertoldi et al. specifically, basal paz ber-9 is characterized by high percentages of the pinus-group (about 60% of the pollen sum), a decrease of the picea curve and very low ap concentrations (about 2,500 grains/g). the overlying paz ber-10 is characterized by a further decrease in the pinus-group, which falls at about 40% of the total pollen, a rise of herbs (especially artemisia) and the continuous presence of betula, which reaches 20% of the total sum in the uppermost pollen spectra. at first, the quercetum elements (essentially quercus and corylus grains) are scattered and dispersed. however, they increase and become continuous in the upper spectra of this pollen zone. picea shows a gradual decrease and abies is sporadic. ap concentrations are significant, since they vary from 7,500 to a maximum of 15,000 grains/g in the upper part of paz ber-10. the transition to the upper segment of the sequence, from 6.20 to 4.30 m of depth (paz ber-11), is marked by a sharp sedimentary gap, which results in a dramatic change in the overall vegetational state in respect to the lower paz ber-10. indeed, a cyclical turnover between abies and quercetum is observed, along with the decrease of other arboreal and nonarboreal taxa, apart from the other ap-group (alnus, salix, populus). ap concentrations raise up to the maximum value detected throughout the succession (about 190,000 grains/g). chronostratigraphy and vegetational-climatic features interpretation of the berceto succession can be attained by integrating floristic and biostratigraphic data with radiocarbon ages. globally, the berceto pollen sequence yielded an overall “modern” arboreal flora, which closely resembles the present-day woodlands of northern italy. therefore, it is strongly suggested, based on pollen evidence, that the berceto succession was laid during upper pleistocene and holocene times. the lower segment of the pollen diagram (fig. 4) shows four pollen zones paz ber-2, ber-4, ber-6 and ber-8 characterized by boreal-like pinus forests with picea alternating with four paz ber-1, ber-3, ber-5 and ber-7 characterized by steppe/forest-like of pinus. the radiocarbon ages from bulk sediment recovered at 22.50 and 11.65 meters depth (table 1) allow us to arrange chronologically the pollen zones sequence. the paz ber-1 and ber-2 are probably older than 30,000 year bp. the time interval between paz ber-3 and ber-8 corresponds very well to the last würmian pleniglacial (orombelli & ravazzi, 1996). the vegetation pattern suggests that in the mountain belt of northern apennines, drastic changes took place in the regional availability of effective moisture. specifically, the significant abundances of picea amidst the open pine woodlands is indicative of continental and moderately humid climates, which can be regarded as “interstadial” intervals. by contrast, the dominance of steppe/forest communities with pinus stands suggests harsher climatic conditions, thus fully consistent with “stadial” intervals. the middle segment of the succession encompasses the lateglacial, although documentation is interrupted abruptly by a sedimentary gap immediately above 11,150±70 14c yr bp, i.e. at 6.20 m depth. paz ber-9 represents a stadial interval, being characterized by the abrupt increase of herbs (nap) in an open woodland with pine. in contrast, the following paz ber-10 documents a more forested phase, evidenced by two distinct increases of the ap pollen concentration, with dominant pinus and, secondly, betula. the pollen features of ber-10 suggest that a transient reforestation event of the apennine slopes took place, principally in response to a significant increase in average temperatures. still, the overall sporadic occurrence of water-demanding trees suggests that effective moisture remained low, although in the uppermost spectra a slight increase in temperate elements is observed. in the uppermost segment of the sequence, i.e.: paz ber-11, abies and quercetum are dominant. this interval is in stark contrast with the previous ones, being characterized by vegetational features that are fully consistent with a postglacial phase. 4.2 lagdei site pollen flora the ap findings, as pinus, abies, quercus, tilia, ulmus, corylus, alnus + salix + populus, show widely variable curves. low and discontinuous values of juniperus, hippophae, picea, betula, acer, fraxinus, fagus, taxus (cf.) and other ap (traces of carpinus, ostrya, castanea, juglans, ilex, hedera ,viscum, cornus, etc) occur (fig. 5). the nap flora is qualitatively and quantitatively rich. the most important taxa are artemisia and other asteraceae and poaceae. chenopodiaceae, ranunculaceae with thalictrum, helianthemum, ericaceae, plantaginaceae, polygonaceae, caryophyllaceae, brassicaceae, umbelliferae, rosaceae show discontinuous curves. other nap, such as dipsacaceae, fabaceae, campanulaceae, rubiaceae show only sporadic values and the hygrohydrophyta (cyperaceae, sparganiaceae, typhaceae, hydrocharitaceae) are scarce. findings of ephedra were found only in the lower spectra. biostratigraphy and chronostratigraphy in the continuous and undisturbed lagdei-ii lacustrine succession, pollen data demonstrate that the interval between 2.40 and 8.30 m depth documents the lateglacial and the early postglacial. very good agreement exists 9 dating code sample conventional 14c age calibrated 14c age depth (m) (14c yr bp) (cal yr bp) beta 178882 6.20 11,50±70 13,390-13,240/13,240-12,900 beta 181866 11.65 14,80±50 17,705-17,00 beta 181867 22.50 19,620±290 -----------table 1 results of 14c datings from berceto core (beta analytic inc, miami, florida, u.s.a.) (from bertoldi et al. 2004). risultati delle datazioni radiocarbonio dei campioni di berceto (beta analytic inc, miami, florida, u.s.a.) (da bertoldi et al. 2004). new data from northern apennines ... 10 f ig u re 4 s u m m a ry p o lle n p e rc e n ta g e d ia g ra m o f b e rc e to w it h s e le c te d s in g le t a xa ( b e tu la , p ic e a , a b ie s) a n d p o lle n g ro u p in g s. t h e p e rc e n ta g e s a re c a lc u la te d w it h r e sp e c t to t h e t o ta l p o lle n s u m . o n t h e le ft o f th e d ia g ra m a re r e p re se n te d t h e s tr a ti g ra p h ic c o lu m n , th e r a d io c a rb o n d a ti n g s a n d , o n t h e e xt re m e r ig h t, t h e a p c o n c e n tr a ti o n c u rv e . il d ia g ra m m a p o lli n ic o r ia ss u n ti vo d i b e rc e to m o st ra s in g o li ta xa s e le zi o n at i ( b e tu la , p ic e a, a b ie s) e r ag g ru p p am e n ti p o lli n ic i. l e p e rc e n tu al i s o n o c al c o la te r is p e tt o a lla s o m m a to ta le d e i p o lli n i. s u lla s in is tr a d e l d ia g ra m m a so n o r ap p re se n ta te : la c o lo n n a st ra ti g ra fic a e le d at az io n i r ad io c ar b o n io ; al l’e st re m it à d e st ra è r ip o rt at a la c u rv a d i c o n c e n tr az io n e a p . r. bertoldi et al. 11 f ig u re 5 a n a ly ti c a l p o lle n p e rc e n ta g e d ia g ra m o f l a g d e iii. p e rc e n ta g e s re fe r to t h e p o lle n s u m ( a p + n a p ). d ia g ra m m a p o lli n ic o a n al it ic o d i l ag d e iii. l e p e rc e n tu al i s i r ife ri sc o n o a l c o n te g g io t o ta le d e i p o lli n i ( a p + n a p ). new data from northern apennines ... both in tempo and modes of the dynamics of the floristic taxa found in this sequence with respect to the previous one reported in bertoldi (1980). the criteria employed for subdividing the lagdei-ii pollen record (fig. 6) into 6 pollen assemblage zones, namely paz lgd-a to paz lgd-f, are the same as bertoldi (1980) here integrated with the ap concentration datum. as a result, it was at first demonstrated that the former subdivision proposed is in excellent correspondence with the zonation established in the lagdei-ii pollen record, where 4 age control points based on radiocarbon dating are also available (table 2). a major result is represented by the firm recognition of the lateglacial/ postglacial boundary, which occurs at 6.75 m depth in close correspondence to a manifest change both in vegetation and in sedimentation. age of the boundary is approximated by the radiocarbon age of 9,900±80 14c yr bp derived from a peaty sample at 6.50÷6.60 m depth. the transition to the postglacial is continuous and well documented by the stratigraphic sequence and pollen record, being correlative to the sharp transition from paz lgd-c to paz lgd-d. this is in agreement with the data derived from the core drilled in the centre of lagei hollow in 1980. besides this, the radiocarbon age 9,620±70 14c yr bp at 6.00÷6.10 m depth supports the attribution of the paz lgd-d to the basal holocene. the other radiocarbon datings (8,190±70 14c yr bp at 4.50÷4.60 m and 6,840±60 14c yr bp at 2.43÷2.53 m of depth) allow us to attribute the paz lgd-e and lgd-f to the early-middle holocene (table 2; fig. 6). paz lgd-a, lgd-b and lgd-c belong to the lateglacial. however, radiocarbon ages are not available in this segment and therefore, chronology of paz lgd-a, lgd-b and lgd-c is based on the occurrence of prominent vegetational features. paz lgd-a is consistent with the oldest dryas, being characterized by minimal ap concentrations (<1,000 grains/g) that document a steppe-like landscape with sparse pinus stands. paz lgd-b represents a closing pinus forest with scattered occurrences of other trees such as betula, picea, quercus, alnus and salix. the peculiar pollen assemblage and the increasing ap concentration (from 1,000 to 20,000 grains/g) are in full agreement with the well-known interstadials of the lateglacial. specifically, the two-folded distribution pattern of the ap concentration curve suggests that paz lgd-b encompasses the bölling alleröd interstadial complex. paz lgd-c is characterized by a culmination of the pinus-group curve, along with a decrease of herbs (especially the artemisia-group) and a sharp fall of the ap concentration. this interval is logically correlative to the younger dryas stadial oscillation. the beginning of the preboreal (i.e., the base of the holocene) is especially well documented. a last dramatic fall is observed of the pinus-group (base of paz lgd-d), which is gradually replaced by abies and temperate deciduous trees. from this point upwards, all herbaceous taxa are persistently subdued. 5. discussion 5.1 pleniglacial both vegetational data and radiocarbon ages indicate that the interval from ber-3 to ber-8 of the berceto pollen sequence (fig. 4) belongs to the last pleniglacial, which spans from ca. 30,000 to 15,000 yr bp, including the last glacial maximum (lgm) (see e.g. zagwijn & paepe, 1968; mangerud et al., 1974; woillard & mook, 1982; behre, 1989; allen et al., 1999; beaulieu de & reille, 1992; antonioli & vai [eds.], 2004; bini et al., 2004; orombelli et al., 2005). the chronostratigraphic interpretation of the berceto sequence is based on the oscillations of the picea percentage values. indeed, spruce survived during the pleniglacial in the northern apennines in relict area that represented its most southern refuges in europe (ravazzi, 2002). only during the lateglacial began a phase of contraction of the spruce range with its extinction at the beginning of the holocene, except two small areas where the spruce survived (chiarugi, 1936; bertoldi, 1980; ravazzi, 2002; ravazzi et al., 2006). as a consequence, moderate peaks of the percentage pollen curve of picea are climatically significant. the co-variance of the ap concentration curve confirms the significance of the picea culminations. specifically, paz ber-4, ber-6 and ber-8 document short-lived events of climatic amelioration (i.e., interstadials) that are older than 14,480±50 14c yr bp and thus are likely to develop during last pleniglacial times. based on these chronological ties, it is strongly suggested that paz ber-4, ber-6 and ber-8 correlate confidently with the well documented interstadials tursac, laugerie and lascaux that were first recognized and dated in pollen sequences from southern france by leroi-gourhan (1965, 1968, 1980) and confirmed afterwards by laville (1988) and weissmueller (1997). in the light of a long-distance correlation, the berceto pollen emergences are especially worthy of note and provide further evidence that latitudinal control on the vegetation in europe was especially strong during pleniglacial times. so far, indeed, documentation of tursac, laugerie and lascaux interstadials is virtually missing in central europe and north-eastern france (hammen van der et al., 1967; zagwijn & paepe, 1968; frenzel, 1968; woillard, 1978; behre, 1989) and largely 12 dating code sample conventional 14c age calibrated 14c age depth (m) (14c yr bp) (cal yr bp) roma-875 2,43-2.53 6,840±60 7,670-7,570 roma-876 4.50-4.60 8,190±70 9,250-8,990 roma-877 6.00-6.10 9,620±70 10,950-10,500 roma-878 6.50-6.60 9900±80 11,200-10,990 table 2 results 14c datings of lagdei-ii core (14c radiocarbon dating laboratory, dept. of earth sciences, university of rome, italy). risultati delle datazioni radiocarbonio dei campioni di lagdei-ii (radiocarbon dating laboratory, dipartimento di scienze della terra, università la sapienza-roma, italia). r. bertoldi et al. 13 f ig u re 6 s u m m a ry p o lle n p e rc e n ta g e d ia g ra m o f l a g d e iii w it h s e le c te d s in g le t a xa ( b e tu la , p ic e a , a b ie s, f a g u s) a n d p o lle n g ro u p in g s. t h e p e rc e n ta g e s a re c a lc u la te d w it h r e sp e c t to t h e to ta l p o lle n s u m . o n t h e le ft o f th e d ia g ra m a re r e p re se n te d t h e s tr a ti g ra p h ic c o lu m n , th e r a d io c a rb o n d a ti n g s a n d , o n t h e e xt re m e r ig h t, t h e a p c o n c e n tr a ti o n c u rv e . il d ia g ra m m a p o lli n ic o r ia ss u n ti vo d i l ag d e iii m o st ra s in g o li ta xa s e le zi o n at i (b e tu la , p ic e a, a b ie s, f ag u s) e r ag g ru p p am e n ti p o lli n ic i. l e p e rc e n tu al i so n o c al c o la te r is p e tt o a lla s o m m a to ta le d e i p o lli n i. s u lla s in is tr a d e l d ia g ra m m a so n o r ap p re se n ta te : la c o lo n n a st ra ti g ra fic a e le d at az io n i r ad io c ar b o n io ; al l’e st re m it à d e st ra è r ip o rt at a la c u rv a d i c o n c e n tr az io n e a p . new data from northern apennines ... incomplete in the eastern mediterranean region (wijmstra, 1969; bottema, 1979). in central-southern italy, where a fairly complete record of the last pleniglacial is provided by a number of pollen sequences (watts, 1985; follieri et al., 1988, 1989; lowe et al.,1996; allen et al., 1999) tursac, laugerie and lascaux events were not identified, although prominent peaks of ap curves at about 20,000 yr bp were recognized in several crater lakes in the lazio region (follieri et al., 1998; magri, 1999). furthermore, integrated analyses based on a wide range of climatic proxies (geomorphology, geochemistry, magnetic susceptibility, foraminifers) unravelled the occurrence of short-term events of climatic amelioration that are younger than 24,000 yr bp (antonioli & vai [eds.], 2004; carboni et al., 2005). however, in the sedimentary succession of the venice lagoon (northern italy: müllenders et al., 1996; serandrei et al., 2005) tursac and laugerie interstadials were recognized and age-calibrated at 22,270 and 19,060-19,260 yrs bp respectively; a detailed discussion from one of us is available in serandrei et al. (2005). interestingly, such interstadials were not detected by means of pollen analyses in the sedimentary cores recovered from the neighbouring po and veneto floodplains (amorosi et al., 1999, 2004; miola et al., 2003; bondesan et al., 2003). the lascaux interstadial, which is also correlative to the philippi interstadial (tenaghi philippon, greece: wijmstra, 1969), occurs between 17,800 and 16,500 yr bp (leroi-gourhan, 1965, 1968, 1980). this event was not documented in italian pollen records so far, although high-resolution studies have been performed on coeval sedimentary cores from the adriatic sea (zonneveld, 1996). indeed, the lascaux interstadial is not represented in the venice sedimentary succession because of a major stratigraphical gap that occurs in the upper part of the venice core (bortolami et al., 1977). in the lowermost part of the berceto core, a stadial (paz ber-1) and an interstadial (paz ber-2) have been recognized that are older than 29,620±290 14c yr bp. chronology of paz ber-2 is fully consistent with the arcy interstadial, which yielded an age of about 31,000 yr bp (leroi-gouhran, 1968). likely, this event corresponds to the onset of the denekamp interstadial, recognized in central and western europe (hammen van der et al., 1967; zagwijn & paepe, 1968; zagwijn, 1974; mangerud et al., 1974; woillard & mook, 1982; behre, 1989; beaulieu de et al., 1994). warming climatic oscillations referable to the same age but named differently were recognized, thanks to pollen data, both in crater lakes of central italy (follieri et al., 1998; magri, 1999) and in other european regions (gullentops, 1954; lumely de, 1965; wijmstra, 1969). in our opinion the paz ber-1 and ber-2 can be collocated at the end of the middle pleniglacial, as shown in table 3, where the likely correlation between the pollen zones of berceto and the central-southern european climatostratigraphy for the late upper pleistocene is shown. 5.2 lateglacial pollen data and radiocarbon age constraints recovered from the berceto and lagdei-ii records permit the reconstruction of the vegetation history in the mountain slopes of the northern apennines, both at low and high altitude, during the lateglacial period. specifically, the transition from paz ber-8 to paz ber-9 in the berceto sequence (fig. 4), characterized by the abrupt rise of nap and the concomitant decrease of the pinus-group, documents a peculiar vegetational pattern that is also observed at the pleniglacial/lateglacial boundary in southern europe. the pleniglacial/lateglacial boundary yielded an age of ca. 15,000-16,000 yr bp in many pollen sequences from central-western europe and from the adriatic region as well (hammen van der, 1957; zoller, 1960; hammen van der et al., 1967; behre, 1967; grüger, 1975; beaulieu de & reille, 1984a, 1984b; beaulieu de et al., 1985; reille & beaulieu de, 1988; beulieu de & reille, 1992; rossignol-strick et al., 1992; andrieu et al., 1993; beualieu de et al., 1994), in good agreement with the berceto record. indeed, the age datum of 14,480±50 14c yr bp observed at 11.65 m depth in the berceto core suggests that the base of paz ber-9 (at 12.57 m depth) is slightly older than 15,000 yr bp, thus possibly representing the pleniglacial/lateglacial boundary. this horizon was not identified in the lagdei-ii succession, where the boundary is likely to occur beneath the bottom of the recovered core. in the lagdei-ii pollen sequence (fig. 6), the lateglacial/postglacial boundary, as mentioned above, was pinned down at about 6.75 m depth (transition from paz lgd-c to paz lgd-d), in correspondence with the latest sharp decline of pinus, artemisia and other herbs, which occurs in concomitance with the immigration and the prominent increase of abies and warm-temperate trees. a radiocarbon dating performed at 6.50-6.60 m depth yielded an age of 9,900±80 14c yr bp, slightly younger than the age 10,300 yr bp conventionally established for the pleistocene/holocene boundary throughout europe, as testified by the abrupt change in different proxies (e.g. see in: zagwijn & paepe, 1968; zoller, 1960; mangerud, 1982; welten, 1982; burga, 1987; pons & reille, 1988; dansgaard et al., 1989; reille, 1993; beaulieu de et al., 1994; lang, 1994; bottema, 1995; lowe et al., 1996; friedrich et al., 1999). recently, the international commission on stratigraphy (gibbard, 2004) proposed to shift the boundary pleistocene/holocene at 10,000 yr 14c bp (11,550 ± 50 yr cal bp). with respect to the boundaries mentioned above, it is suggested that paz ber-9 and ber-10 of the berceto sequence, as well as the lower part of the lagdei-ii sequence (i.e., paz lgd-a, lgd-b and lgdc), represent the lateglacial. we attempted (table 4) a correlation between the pollen assemblage zones in the study sections and the chronozones as proposed and calibrated by mangerud et al. (1974). the ap concentration curve, which testifies the degree of arboreal coverage during the considered time interval, demonstrates that a significant correlation exists between major forestation events at berceto and lagdei. in particular, a steppe-woodland with pinus extended in the mountain slopes of the northern apennines during the oldest dryas. the observed lesser discrepancies in ap concentrations may still depend on the different altitudes of the studied sites. on the contrary, a sharp increasing trend of ap concentrations is documented in the upper lateglacial 14 r. bertoldi et al. chronozones, which are correlated to the böllingalleröd interstadial complex. in the berceto record, the percentages of the quercetum (essentially quercus and corylus), at the beginning overall sporadic, become continuous and important starting from the end of the alleröd interstadial. however, the stratigraphic record is interrupted abruptly at 11,150±70 14c yr bp, in relation to a major coring hiatus that hampered the preservation of the final lateglacial-early postglacial interval. on the other hand, the interval straddling the bölling-alleröd chronozones is continuous in the lagdei-ii succession, being characterized by the dominance of pinus with betula and the virtual dearth of temperate deciduous trees. paz lgd-c, similar indeed to paz lgd-b in terms of vegetation, corresponds to 15 table 3 local pollen assemblage zones, vegetational and climatic succession of the berceto core tentatively related to the main chronologic and climatostratigraphic units used in central-southern europe for the late upper pleistocene. tentativo di correlazione tra zone polliniche, successione vegetazionale e climatica di berceto con le unità cronologiche e climatostratigrafiche dell’europa centro-meridionale del tardo pleistocene superiore. new data from northern apennines ... the younger dryas as suggested both by the fall of the ap concentrations and radiocarbon datings. changes in ap concentrations and fluctuations of the ap/nap ratio in the study sections provide further information on the past altitude of both timberline and treeline during the latest pleistocene in the northern apennines. the beginning of mixed massive forestation after the lgm in the appennino parmense is apparently delayed with respect to other italian regions characterized by more favorable climates. indeed, the delayed northward diffusion of both abies and quercetum elements during postwürmian times was already documented in central and northern apennines (ferrarini, 1962). in central italy, the diffusion of temperate deciduous trees began after the lgm and came to a completion during lateglacial interstadials (follieri et al., 1988, 1989, 1998; magri, 1999; lowe et al., 1996; drescher-schneider et al., in press). in the insubrian lowland areas (northern italy), the same process begun during the alleröd interstadial and ended at the beginning of the holocene (zoller, 1960; beug, 1964; bertoldi, 1968; schneider, 1978, 1985; wick, 1996; gobet et al., 2000). pollen data from berceto and lagdei-ii document that the immigration of temperate deciduous trees in the northern apennines occurred at the end of alleröd interstadial at low altitudes (e.g. berceto, 820 m a.s.l.), whilst immigration and expansion of quercetum elements occurred at the beginning of the holocene at higher altitudes (e.g. lagdei, 1,254 m a.s.l.). chronological and vegetational constraints arising from this paper shed new light on both the tempo and fashion of forest development and dynamics in the northern apennine area during the lateglacial. in particular, our new data permit a reassessment of the pollen-based age model developed for the previous lagdei pollen record by bertoldi (1980). the latter interpretation was radically emended by lowe (1992) and lowe & 16 table 4 schema of the role of the principal arboreal and herbaceous taxa and correlation with the chronology for the lateglacial and early-middle holocene in the appennino parmense. schema del ruolo dei principali elementi arborei ed erbacei e loro correlazione nel quadro cronologico del tardoglaciale e dell’olocene inferiore e medio nell’appennino parmense. r. bertoldi et al. watson (1993) order to match the chronology of the prato spilla pollen record (cedra valley) (fig.1), where a mixed forest with abundance of abies and temperate deciduous trees was formerly present at the beginning of the lateglacial interstadials. the model of lowe (1992) and lowe & watson (1993) was challenging because of geobotanical evidence: actually, one had to infer that higher altitudes (that is, prato spilla at 1,350 m a.s.l.) were populated by forests rich in abies and temperate elements, while concomitantly, a pioneer arboreal vegetation almost exclusively, occasionally together with betula, was dominant at lower altitudes (i.e., lagdei, 1,254 m a.s.l. and berceto, 820 m a.s.l.). however, chronological ties presented in this paper provide evidence that the former model of the vegetational development for the lateglacial of bertoldi (1980) was overall correct. furthermore, the age model presented in this paper is supported by vegetation evidence in both berceto and lagdei, which are in good agreement with a number of pollen records either from central or northern italy, as mentioned above. 5.3 early holocene in the lagdei pollen record, paz d, e and f belong to the early-middle postglacial based on distinctive vegetational features. further detail is provided by radiocarbon age constraints, which suggest a correlation between this interval and the preboreal-early atlantic chronozones (table 4). vegetational development in the northern apennines during the holocene is well documented so far (chiarugi, 1936; ferrarini, 1962; braggio morucchio et al., 1978; bertoldi, 1980; bertoldi et al., 1986; gentile et al., 1988; cruise, 1990; lowe, 1992; lowe & watson, 1993; montanari et al., 1994; watson, 1996). in general, the early and middle holocene is dominated by mixed communities with abies and quercus, while during the middle-late holocene fagus is dominant. the immigration of fagus in the northern apennines postdates 6,800 yr bp (this paper), while its massive diffusion took place after 5,000 yr bp (lowe, 1992). as stated above, the base of paz ber-11 in the berceto record is marked by a major stratigraphic hiatus and the entire pollen zone is characterized by abundant abies and quercetum elements, while fagus is absent. this vegetational assemblage suggests that paz ber-11 belongs to the early holocene (table 4). 6. conclusions the studies performed on the lacustrine sediments of berceto and lagdei permitted us, as a whole, to obtain new data on the vegetational and climatic features that characterized the northern apennines starting before 30,000 yr b.p. the long time interval encompassed by the two sequences allowed the reconstruction of a succession of stadial/interstadial cycles that started in the latest middle pleniglacial, where a climatic cycle likely correlated to the arcy events was found. the onset of the last pleniglacial is older than of 29,620±290 yr bp and coincides with the beginning of paz ber-3, while its culmination is not settled in the pollen sequence. it is represented by alternanting stadial/interstadial events recorded in berceto core before 14,480±50 yr b.p. we stress that the events of climatic amelioration are tentatively correlated with the wellknown last pleniglacial interstadials: tursac, laugerie and lascaux. during which a boreal-like pinus forest with picea existed and climatic conditions characterized by a relative improvement of the temperature and, especially, by a slight increase in humidity occurred. the stadial phases were characterized by a steppe-woodland with pinus and moreover the pollen spectra testify cold continental climatic conditions, but not very dry. the pleniglacial/lateglacial boundary was recognized in a pollen succession and it is placed just before 14,480±50 yr b.p. the pollen results demonstrate that a steppeforest with pinus existed in the mountain region during the lowest lateglacial stadial (oldest dryas), while a boreal-like pinus forest with low values of picea and betula existed during the lateglacial interstadials at altitudes exceeding 800-900 m. a mixed pinus-betula woodland with broad-leaved trees, mostly quercus and corylus, occurred at lower altitudes only at the end of the alleröd interstadial, precisely at 11,150 ± 70 14c yr bp. the density of these woodlands is documented by significant variations of ap concentration values. from our pollen data the lateglacial/postglacial boundary, that occurred just before 9,900±80 yr b.p., is very prominent. indeed it records the definitive fall of the pioneer arboreal vegetation (pinus-group) and the diffusion and fast expansion of the abies and of the temperate deciduous trees. on the contrary the climatic cooling of the younger dryas has little evidence in the pollen spectra of the parma valley. indeed it is marked overall by the sharp fall of the ap concentration curve. this fact means that during this period an open woodland occurred in the higher mountain belt. this is in agreement with some findings in southern europe, where a diminution of the cooling effect during the younger dryas southwards across the continent was found (woillard & mook, 1982; watts, 1985; turner & hannon, 1988; rossignol strick et al., 1992) this palaeoenvironmental picture is in agreement with the geomorphological evidence in the northern apennines. this climatic event corresponds to the third glacial stage of federici & tellini (1983), during which glaciers were absent in parma valley or only small ones were confined in the cirques with an northern aspect. acknowledgements this work was supported by the local research fund fil 2006 (head: s. perego-università di. parma). the authors are grateful to the referees donatella magri and laura sadori (università la sapienza, rome) for the careful reading of the text, the useful suggestions and comments that helped to improve the manuscript. besides we are grateful to walter finsinger (university of utrecht) for the critical review of the manuscript. we are grateful to gilberto calderoni (radiocarbon dating laboratory of università la sapienza-rome) that performed the datings of lagdei core. 17new data from northern apennines ... references allen jrm., brandt u., brauer a., hubbertens hw., huntley b., keller j., kraml m., mackensen a., mingram j., negendank jfw., nowaczyk nr., oberhänsli h., watts wa., wulf s. & zolitschka b. 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(1996) palaeoclimatic reconstruction of the last deglaciation (18-8 ka b.p.) in the adriatic sea region; a land-sea correlation based on palynological evidence. palaeogeography palaeoclimatology palaeooecology, 122, 89-106. 20 ms. ricevuto il 12 dicembre 2006 testo definitivo ricevuto il 14 marzo 2007 ms. received: december 12, 2006 final text received: march 14, 2007 r. bertoldi et al. microsoft word 00_indice_bm03 available online http:/amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 25 (1), 2012, 15-23 sea level change in western-central mediterranean since 300 kyr: comparing global sea level curves with observed data fabrizio antonioli enea utmea, casaccia, roma, italy corresponding author: <fabrizio.antonioli@enea.it> abstract: in this study, we used published sea level markers to provide a review of observational data for the western-central mediterranean during the last 300 kyr. for the last interglacial (mis 5.5, 125 kyr bp) and holocene (10 kyr cal bp) periods, hundreds of data have been observed, measured, and dated using 14c, u/th, amino acid racemization (aar), and electron spin resonance (esr) methods. the maximum highstand for a mis 5.5 sea level is normally set at 7±2 m. this altitude remains a key value for the mediterranean sea and is often used to establish the neotectonic stability of coastal areas or to uplift/downlift rates in a tectonically active coast. information on mis 9 is available only from cores or terraces in tectonically active coastal areas. knowledge on mis 7 was recently improved by papers reporting precise sea level data from submerged speleothems in a stable coastal area: the argentarola cave (tyrrhenian sea, italy). these data (highstand duration and sea level) agree with global eustatic sea level curves. on the contrary, few observed data are available for mis 3, 5.1, and 5.3. moreover, most of these data disagree with global sea level curves. only one recorded and dated observational datum for mis 2 was published for the late glacial maximum (lgm) lowstand (-129.5 m in sicily). this datum agrees with global sea level curves and predicted sea level data from glacio-hydro-isostatic models. with regard to the holocene period, it can be assumed that sea level changes along the mediterranean coasts are the sum of eustatic, glacio-hydro-isostatic, and tectonic factors. the first is only time dependent, while the latter two also vary with location, which means that at the same time slices the sea level (the sum of three different movements) may be different in different coastlines. keywords: western-central mediterranean, global sea level change curves, observational data, last 300 kyr. 1. introduction this paper tries to use state-of-the-art methods in determining the observational points well connected to sea levels, comparing them with global sea level curves. this review constitutes a starting point for improving the observational data required for the projection of future coast scenarios. in some periods, such as mis 9 and 3, no observed data are available in stable coastal areas: for completeness of information, data are reported also in tectonically active areas, corrected with tectonic rates. the largest uncertainty in future sea level rise stems from our lack of a clear understanding of the dynamic response of ice sheets to anthropogenic climate change. the paleo records of sea level changes are potential resources to better constrain estimated future sea level rise (ipcc, 2007). sea level (hereafter, sl) variations during the last 300 kyr were caused by solar insolation (fig. 1) and ice melting, and they vary between +7 and -135 m in stable coastal areas in the western-central mediterranean sea (waelbroek et al., 2002). global sl curves are generally constrained by analyzing the δ18o ratio in the fossil foraminifera series, sampled on either the shelf edge or the ocean floor. changes in the δ18o ratio show a direct correlation with sl variations, allowing a quantitative estimate of sl changes. these curves do not take into account any isostatic or tectonic component. the global sl curves reported by waelbroek et al. (2002) (fig. 2) and siddal et al. (2003) were used in the present study. these authors show that robust regressions can be established between the relative sea level data and the oxygen isotope ratios of benthic foraminifera from the north atlantic ocean and the equatorial pacific ocean over the last climatic interglacial cycle. sea level predictions for the last 20 kyr using isostatic models are accepted worldwide. these models are often tested with observational data in tectonically stable areas. the isostatic contribution for mis 5 has been the subject of recent publications (potter & lambeck, 2004, for mis 5.3 and 5.1 and lambeck et al., in press, for mis 5.5), but for the mediterranean sea, the geophysical data are still lacking. completing these data will be the main challenge in sea level studies in the next years. 2. data mis 9 waelbroek et al. (2002) and siddal et al. (2003) indicated that during mis 9.1, the sl stand was at -17 and -38 m, respectively (table 1). no observational data are reported for stable coastal areas of the westerncentral mediterranean sea during mis 9. with regard to tectonically active coasts (either subsiding or uplifting), in a core drilled in the fondi plain (antonioli et al., 1988, a slightly subsided coastal area, tyrrhenian sea, central italy), sediments containing marine fossils found at 32 m were dated using amino acid racemization (aar) at aminozone g (mis 9). in the core “venezia 1,” kent et al. (2002) indicated the presence of marine sediments antonioli f. 16 during mis 9 at about -200 m. this area indicates a negative downlift of about -0.6 mm/year for the last 125 kyr and a mean of 0.36 mm/year for the last 700 kyr. in southern calabria, italy, miauyci et al. (1994) correlated mis 9 with terrace viii at about +300 m and indicated a mean of about +1 mm/tear for the last 125 kyr, in agreement with the data of westaway (1993). mis 7 for mis 7.1, 7.3, and 7.5, waelbroek et al. (2002) indicated that the sl was located at -10, -4, and -9 m, respectively, below the present sea level. in siddal et al. (2003), on the other hand, the sl is at -5, -29, and -3 m, respectively (table 1). in italy, a mis 7 record was found and dated in a submerged cave. the cave is located in a coastal area (in the argentarola island, central italy) that can be considered tectonically stable (bard et al., 2002). some speleothem samples from the cave are peculiar because they recorded several continental marine transitions. during lowstands, when the cave was emerged, dense sections of speleothem calcite were formed. during highstands, on the other hand, the argentarola cave was flooded and stalagmites were covered by colonies of the marine worm serpula massiliensis. in the same cave, bard et al. (2002) and dutton et al. (2009) determined that the sea level elevation peaked at -18 m during the mis 7.3 highstand and was between -18.5 and -21.0 m during the mis 7.2 lowstand. in contrast, the peak sea levels during mis 7.5 and 7.1 were above the highest reference point in the cave (-18 m). the observed lower peak sea level during mis 7.3 relative to mis 7.5 and 7.1 agrees with sea level reconstructions of global sl curves that are based on seawater δ18o determinations and with the flowstone dwbah sampled in submerged cave in bahamas (richards et al., 1994). underwater investigations along italian coasts (antonioli & ferranti, 1994; rovere et al., 2011) have shown a recurrent paleo-sea level from -15 to -20 m. geomorphological evidence of this sea level remains at subhorizontal abrasion surfaces, which are visible on a cliff bordering some carbonate promontories. antonioli & ferranti (1994) related the submerged terraces to mis 3, but i agree with rovere et al. (2011) that these submerged terraces could be related to mis 7 or, alternatively, to lower mis 5 stages. tectonically active coastal areas: using aar methods, de santis et al. (2010) found and dated mis 7 marine sediments at -32 m in a core in a slowly downlifting area in the apulia coast. on the other hand, using fig. 1 summer insolation at 65°n, from berger 1978. global sea-level curve from imbrie et al., 1984. fig. 2 global sea level curve from waelbroek et al. (2002) with observational data in stable areas quoted in this paper (green ballon) and argentarola marine (blue) continental brown) layers. sea level change in western-central mediterranean since 300 kyr… 17 tims u/th, antonioli et al. (2009) found and dated a mis 7.1 (197 kyr bp) sample of cladocora caespitosa at -72 m in the enea core in versilia, central italy. in southern calabria, miauyci et al. (1994) correlated a terrace located at about +250 m to mis 7. mis 6-5.5 few observational records show a very rapid oscillation of sl, named termination ii, at about 135 kyr bp, which cannot be explained by the milankovitch theory in its simplest form. after tectonic corrections, data show that sl reached -18 m around 135.8 kyr bp on the barbados coral reefs (gallup et al., 2002) considered slowly uplifting. at huon peninsula (papua new guinea), esat et al. (1999) dated some corals from the “aladdin’s cave” evaluating a sl of -14 m at 135 kyr bp and a drop in sl of 80\60 at 130 kyr bp after tectonic corrections. no in situ observational data have been found in the mediterranean sea, but capozzi & negri (2009), and references therein, observed termination ii in an isotopic study of planktonic and benthic foraminifera. mis 5 mis 5.5 the last interglacial (lig) shoreline coincides with mis 5.5, which occurred between 132 and 116 kyr bp (stirling et al., 1998; shackleton et al., 2003). the global sl curves (waelbroek et al., 2002; siddal et al., 2003) indicated sl at +7 and +17 m, respectively (table 1). a statistical approach on a worldwide compilation of data was published by kopp et al. (2009), who determined the posterior probability distribution of lig sl and ice volume through time, concluding that the highglobal sea level curve mis age metres age ka observed sea level mis / age metres 1 lambeck et al., 2011 predicted s.l for trieste 8 ka cal bp -11.2 m 1 lambeck et al., 2011predicted s.l for nora 8 ka cal bp -18.7 m lambeck et al, 2011 2 predicted s.l for termini imerese (sicily, italy) 20 ka cal bp -127 m waelbroek et al., 2002 2 -123 20 caruso et al., 2011, observed on termini imerese continental shelf 21.8 ka cal bp -129.5 m siddal et al 2003 2 -115 19.5 waelbroek et al., 2002 3.1 -62 39.5 carboni et al., 2010, amorosi et al 2004, 3.1 not present at -60 m siddal et al 2003 3.1 -74 33.6 belluomini et al., 2002 3.1 +1 waelbroek et al, 2002 3.3 -48 60.5 antonioli et al., 2004 3.3 deeper than -21 siddal et al 2003 3.3 -53 66 iannace et al., 2003 3-4 waelbroek et al, 2002 5.1 -19 81.5 dorale et al., 2010 81 ka +1 siddal et al 2003 5.1 -28 82.9 riccio et al., 2001, 2003; iannace et al., 2003, mastronuzzi 2007, hearty 1986, rodriguez vidal et al 2004 5.1 +1 and +5 waelbroek et al, 2002 5.3 -21 102 amorosi et al., 2004 5.3 -12 siddal et al 2003 5.3 -27 107 riccio et al., 2001; iannace et al., 2003, zazo et al 2009, rodriguez vidal et al 2004 5.3 between +6 and +2 m waelbroek et al, 2002 5.5 7 124 lambeck et al 2004, ferranti et al. 2006, 2010 5.5 between +6 and +8 m siddal et al 2003 5.5 17 123 waelbroek et al, 2002 6.5 -50 167 bard et al 2002 6.5 deeper than -22 m siddal et al 2003 6.5 -32 177 waelbroek et al, 2002 7.1 -10 189.7-201.5* bard et al., 2002, dutton et al., 2009* 7.1 above -18 m siddal et al 2003 7.1 -5 waelbroek et al, 2002 7.3 -4 206.0-217.2* dutton et al., 2009* 7.3 -18 m siddal et al 2003 7.3 -29 waelbroek et al, 2002 7.5 -9 231.0 – 248.9* dutton et al., 2009* 7.5 above -18 m siddal et al 2003 7.5 -3 waelbroek et al, 2002 9.1 -17 288 siddal et al 2003 9.1 -24 287 tab. 1 global sea level curves compared with predicted and observed sea level data in stable areas for western-central mediterranean sea. antonioli f. 18 stand peak was very likely to have exceeded 6.6 m and was likely to have been above 8.0 m although it is unlikely to have exceeded 9.4 m. according to siddal et al. (2010), the palaeosealevel data from farand medium-field sites for the lig period suggest that sl is attained close to its peak of 3–6 m above the modern sl by 126 kyr bp. pedoja et al. (2011) provided a compilation of 890 records of paleo-shoreline sequences for mis 5.5. they showed that “most coastal areas have risen relative to sea level with a mean uplift rate higher than 0.2 mm/a, more than four times, faster than the estimated eustatic drop in sl.” the study concludes that plate-tectonic processes affect all margins and emphasizes the fact that the notion of a stable platform is unrealistic. these results, therefore, “seriously challenge the evaluation of past sl from the fossil shoreline record.” in a recent paper, lambeck et al. (in press) demonstrated that “like their holocene counterparts, sl during earlier interglacials can be expected to exhibit considerable spatial variability that depends on the location of a site relative to ice margins of both the immediately preceding glacial maximum and of the last glacial maximum, and on the earth’s rheological response function response functions". their data show impressive differences (up to 15 m) for the lig highstand in stable coastal areas, such as australia, the caribbean, and red sea. in southern spain, zazo et al. (1999) found and studied many sites between +20 and +1.5 m sl, dated mis 5.5. for the italian coast, lambeck et al. (2004) assumed a “nominal” age of 1245 kyr and an elevation, in the absence of tectonics, of 73 m above the present sl. this elevation is higher than global estimates of this level because “the italian sites lie relatively close to the former ice margins and the present mis 5 shorelines in the mediterranean may lie a few meters higher than for localities much further from the former ice margins” (potter & lambeck, 2004). these values are consistent with observations of tidal notches from sardinia, southern lazio, campania, and western sicily, which are believed to have been tectonically stable during the recent glacial cycles. tidal notches, due to the low amplitude of tides in italy (a mean of about 40 cm, with the exception of ne adriatic and the gulf of gabes in tunisia), are considered the best sl markers. a recent compilation of mis 5.5 sea level markers on 246 sites spanning the coastline of italy (ferranti et al., 2006) allows the distinction between stable and tectonically active coastal areas since the late pleistocene (fig. 13 of this paper). figure 1 of ferranti et al. (2006) shows the distribution of mis 5.5 markers in the whole mediterranean sea that vary between 125 m (po plain, italy) and +190 m corinth, greece). this paper was implemented by new findings on the altitude of mis 5.5 highstand in tuscany and ne adriatic sea (antonioli et al., 2009; ferranti et al., 2010). data from tectonically stable sites confirm that the highstand altitude reached by the sea in italy during mis 5.5 was 7±2 m above the present sl. a compilation of new and published evidence related to mis 5 in southern spain (considered stable since 125 kyr bp) was published by bardaji et al. (2009), the authors concluded that “the palaeontological, sedimentological and geomorphological records of mis 5 deposits in the western mediterranean, allows the proposal of a model for the connections between this basin and high latitude climatic changes in the northern hemisphere, in comparison with modern analogues, in this paper authors published an eustatic curve for the lig” (fig. 3). mis 5.3 the global eustatic curves (waelbroek et al., 2002; siddal et al., 2003) indicate that the sea level during mis 5.3 was located respectively at -18.7 and -28 m (table 1). for mis 5.3, there are some observational data in the mediterranean in southern spain (zazo et al., 1999), which attribute to mis 5.3 some deposits (dated using the u/th method) at altitudes between +6 and 0 m. in the vicinity of gibraltar, considered stable since 125 ka, rodriguez-vidal et al. (2004) found deposits dated mis 5.3 at +5 m. in italy, a flowstone covering a marine conglomerate and lying a few meters above the present sl was attributed to mis 5.3 on the basis of u/th ages (riccio et al., 2001; iannace et al., 2001, 2003). transgressive lagoonal facies from the po plain (see core 240-s8 in amorosi et al., 2004) were assigned a mis 5.3 using the electron spin resonance (esr) method on mis 5.5 fig. 3 eustatic sea level curve for the last interglacial using mallorca data (gines et al., 2001), from bardaji et al. (2009). sea level change in western-central mediterranean since 300 kyr… 19 lagoonal deposit (ferranti et al., 2006). taking into account the present altitude of this deposit and the subsidence rates calculated using mis 5.5 (about 1 mm/yr), a relative sl of -12 m can be established for mis 5.3. the sediments of mis 5.3 (and 5.1) were not found in the veneto and friuli plain cores (north adriatic sea, antonioli et al., 2009; ferranti et al., 2010) affected by a negative tectonic between -0.6 and -0.4 mm\a. the authors interpreted this lack for the low seabed bathymetry of the north adriatic sea (about 10 m, some kilometres from the present coastline): a confirmation that the altitude of these mis was not higher than -15 m. mis 5.1 waelbroek et al. (2002) and siddal et al. (2003) indicated for mis 5.1 a sl located at -21.2 and -26.7 m, respectively (table 1). the observational data of mis 5.1 deposits from coral reefs in the caribbean sea seem to disagree with the g.slc. in particular, discrepancies are found in transects in stable areas for the coast of haiti, bermuda, bahamas, south carolina, and florida, with altitudes varying between -20 and +5 m. these controversial observations, however, are reconciled, taking into account the isostatic response of the earth due to the north american ice sheets melting during the last glacial cycle (potter & lambeck, 2004). in the vicinity of gibraltar, considered stable since 125 kyr, rodriguez-vidal et al. (2004) reported that deposits of mis 5.1 are found between +2 and +1.5 m. a mis 5.1 sea level at about +1 m was recorded using phreatic speleothem sampled in a partially submerged cave at mallorca in the western mediterranean (dorale et al., 2010). in southern italy, a marine deposit located a few meters above the present sea level and attributed to mis 5.1 based upon aar was reported by hearty (1986). in the grotta del diavolo (apulia, considered a stable coastal area) (ferranti et al. 2006, mastronuzzi et al. 2007) studied and dated some marine deposits covered by flowstone. the u/th age calculated for the continental deposit allowed us to establish that mis 5.1 is marked by a sea level position slightly higher than the present one. in the argentarola cave, the δ18o series on mis 5 of a marine layer (serpulids) conserved in a speleothem at -18.5 m shows a continued deposition during mis 5 (antonioli et al., 2004). the lack of any hiatuses on the marine layer allows us to establish that the sea level never fell below -22 m during mis 5.2 and 5.3. the presence of two closely spaced tidal notches, both attributed to mis 5.5, has been reported by antonioli et al. (2006) in sardinia (orosei gulf), a stable coastal area in italy. there is no evidence in these studied sites for tidal notches at altitudes lower than mis 5.5 (fig. 4). the observational altitude of mis 5.1 in the mediterranean sea sometimes disagrees with global sea level curves and remains a debated problem, which is also due to the lack of reliable isostatic models for mis 5. mis 3 for mis 3.3 and 3.1, waelbroek et al. (2002) indicated that the sea level was located at -39.5 and -60.5 m, fig. 4 orosei gulf, sardinia, italy the tidal and smoothed notches of the mis 5.5 highstand (see also antonioli et al., 2006). antonioli f. 20 respectively, whereas siddal et al. (2003) calculated the values -33.6 and -53 m for the same time intervals (table 1). data from the mediterranean sea are scarce for france. lambeck & bard (2000) wrote: “during stage 3, sea levels do not appear to have risen locally above about -60 m.” a marine deposit close to the present sea level was found in the taranto gulf (mis 5.5 between 3 and 20 m (ferranti et al., 2010) and dated to mis 3 using the aar method (belluomini et al., 2002). u/th dating of a flowstone overlying a marine conglomerate a few meters above sl allowed a correlation of the marine deposit to mis 3 (iannace et al., 2003) in campania in a stable coastal area. both findings disagree with global sea level curves. subsurface data from the po plain (cores published by amorosi et al., 1999, 2004) document that mis 3 is represented by paludal and alluvial facies, with no intervening marine deposits. the same occurs in the versilia plain (tyrrhenian sea, central italy) where carboni et al. (2010) studied the enea core up to -75 m. mis 2 for mis 2 (lgm), waelbroek et al. (2002) and siddal et al. (2003) located the sea level at -123 and 114 m, respectively (table 1). for the mediterranean side of france, lgm shorelines are reported between 105 and -115 m below the present level. this range reflects the importance of the isostatic contributions for southern france. predicted sl values for italy (lambeck et al., 2011), which take into account the effects of glacio-hydroisostatic movements, range between -130 and -108 m. lgm transgressive deposits recovered in a vibrocore sample on the shelf edge of sicily (termini imerese) at 129.5 m furnished an age of 21.8 kyr cal bp (caruso et al., 2011). these data agree with the local predicted sl curve by lambeck et al. (2011). mis 1 some paintings in the cosquer cave (marseille, france) aged 19 kyr cal bp, contained in the final portion of a flooded cave, demonstrate that the seal level maximum highstand was the present sl. (clottes et al., 1997; lambeck & bard, 2000): the legs of horses are painted at tide level, and the bottom was eroded by sea water. on the contrary, the remaining top is perfectly preserved. the holocene sea level change along the mediterranean coast during holocene is the sum of eustatic, glaciohydro-isostatic, and tectonic factors. the first is global and time dependent, while the latter two also vary with location. large collections of holocene data for france and italy, using different markers well connected with sl, were published by lambeck & bard (2000) and by lambeck et al. (2004). this large observational data set was compared with the predicted curves, leading to quantitative estimates of vertical tectonic movements (if present), identification of tectonically stable coastal areas, and paleogeographic reconstructions for the central mediterranean sea at different epochs. these predictions were then extended to the whole mediterranean sea (lambeck & purcell, 2005). a complete review of the holocene data, including the raw data files of the predicted sl data for 40 italian sites, has been published recently [see the supplementary material in lambeck et al. (2011)]. significant differences can be observed in stable coastal areas if different sites are considered: as an example, the sea level at 10 kyr cal bp varies along the italian coasts between -48 and -35 m, whereas at about 8 kyr cal bp, it ranges between -19 and -11 m (fig. 5). in a recent paper, pavlopulos et al. (2011) provided an extensive holocene data from the coast and islands of greece using archaeological and geomorphological markers. these observational data compared with predicted sea level curves (lambeck & purcell, 2005) allowed us to establish where the coast is stable, uplifting and downlifting, and to provide the tectonic rates. 3. discussion and conclusion we compared eustatic curves presenting different data with different accuracies (i.e., sea level during mis 3.3 set by waelbroeck at -39 m and by siddal at -33 m). there are uncertainties and error margins in the global eustatic sea level curves. figure 6 show the error bar of waelbroek et al. (2002). fig. 5 eustatic and glacio-hydro-isostatic prediction for selected sites in italy for the past 20 ka cal bp from lambeck et al.(2011). sea level change in western-central mediterranean since 300 kyr… 21 in stable coastal areas, data fit global curves in most cases, but there is a need for more reliable observational data sets in the mediterranean. also highlighting and resuming the efforts made in glaciohydro–isostatic, modeling can be a good thing to remember, along with what is needed (i.e., modeling of mis 5). for mis 9, no data are published for coastal areas stable in western-central mediterranean. with regard to mis 7.1, 7.3, and 7.5, data on age, duration, and elevation of the sea level are disposable for the central tyrrhenian sea. mis 7 appears to be below modern sea level, in agreement with global sea level curves. many observational data have been collected for mis 5.5 (ferranti et al., 2006). in sardinia, central mediterranean, well preserved tidal notches provide evidence that mis 5.5 highstand should be considered at 7±2 m. however, after the first published data (lambeck et al., in press) on isostasy during mis 5, it is possible that this is an average value for the central mediterranean sea and that models that take into account the effect of isostatic could modify this altitude in the near future, especially between north and south mediterranean. with regard to mis 5.3 and 5.1, data show in some coastal areas an altitude a few meters above sea level (southern spain mallorca, apulia, campania). on the contrary, with evidence in a core in the po plain, in the north adriatic sea cores, and in tidal notches of sardinia (antonioli et al., 2006), mis 5.3 seems to agree with global sea level curves. at present, it is not possible to determine if the discrepancies are linked to isostasy differences (as observed in other areas, see potter & lambeck, 2004), problems in the interpretation of markers, or problems in dating. mis 3 observational data are scarce and disagree with global sea level curves. for mis 3 the site in apulia is slight uplifting the sites in campania are stable could be possible some aging techniques problems. for mis 2, the predictions of the position of the lowstand for italy (lambeck et al., 2011) and central mediterranean (lambeck & purcell, 2005) were published. the only observational data (caruso et al., 2011) on the north sicilian continental shelf agree with the predictions (table 1). many data about italian continental shelves (chiocchi et al., 2004) described the lgm position at altitude compraised between -95 and -160 m, but these deposits are not radiocarbon aged. much work should be done especially to, i : retrieve observational data older than mis 7, ii : introduce isostasy during and after mis 5 in order to explain the disagreement found for mis 5.3 and 5.1, iii : provide tectonic ratea comparing the observational data to local sea level curves as clearly recomended by caputo (2007), on a paper for the use of global sea level curves. acknowledgements the author is grateful to l. ferranti and a. rovere for useful comments and revisions. references amorosi a., colalongo m.l., fiorini f., fusco f., pasini g., vaiani s.c., sarti g. 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(2002) sea-level and deep water temperature changes derived from benthic foraminifera isotopic records. quaternary science reviews, 21, 295-305. westaway r., 1993. quaternary uplift of southern italy. journal of geophysical research, 98, 2174121772. ms. received: january 22, 2012 final text received: february 21, 2012 base evoluzione geomorfologica quaternaria della conca intermontana di carsoli (aq) maurizio d’orefice1, francesco dramis2, elena graciotti3, roberto graciotti1 & michele soligo2 1ispra – dipartimento difesa del suolo-servizio geologico d’italia, roma. 2dipartimento di scienze geologiche, università “roma tre”, roma. 3libera professionista, via della grande muraglia, 46 roma. corresponding author: m. d’orefice <maurizio.dorefice@isprambiente.it> riassunto: d’orefice m. et al., evoluzione geomorfologica quaternaria della conca intermontana di carsoli (aq). (it issn 0394-3356, 2010). nel presente lavoro vengono esposti i risultati di uno studio a carattere geologico e geomorfologico, condotto nella conca intermontana di carsoli (aq), ubicata nell’appennino centrale, al confine tra le regioni abruzzo e lazio. si tratta di un’ampia depressione di origine tettonica, collocata nel punto di contatto tra due differenti domini paleogeografici, separati da un tratto della linea tettonica “olévano-antrodoco”. la conca di carsoli è colmata da una successione di sedimenti continentali di rilevante spessore ed estensione, i quali sono stati distinti in diverse unità litostratigrafiche. i sedimenti continentali più antichi affioranti all’interno dell’area in studio sono di origine lacustre (limi, argille e sabbie del bosco di oricola). essi sono caratterizzati da uno spessore massimo di circa 200 m e sono diffusi in quasi il 50% della conca, affiorando con una certa continuità nei suoi settori nord-occidentale e centrale (bosco di oricola); affioramenti isolati, invece, sono ubicati lungo il margine orientale della depressione. i sedimenti lacustri, la cui deposizione è probabilmente avvenuta tra il pleistocene inferiore ed il pleistocene medio, sono limitati verso l’alto da una antica superficie di erosione sub-orizzontale, di cui attualmente rimangono solo alcuni lembi relitti. ai depositi lacustri fanno seguito, lungo il bordo nord-orientale della conca di carsoli, sedimenti fluviali grossolani sospesi sull’attuale piana, deposti anticamente da un paleo-turano (ghiaie della madonna delle grazie). nella parte centro-occidentale e meridionale dell’area in esame, inizia bruscamente a partire da un’articolata superficie erosiva modellata nei depositi lacustri e nel substrato carbonatico meso-cenozoico, una significativa sequenza di terreni vulcanici di origine locale, datati intorno ai 530-540.000 anni dal presente. al loro interno sono state distinte tre unità piroclastiche principali, corrispondenti ad altrettanti membri: 1) brecce d’apertura di oricola scalo; 2) tufi grigi di oricola scalo; 3) tufi rossi di s. giovanni. di queste tre unità solo le ultime due affiorano ampiamente nell’area di studio. le brecce di oricola scalo sono relative alla fase d’apertura del condotto. esse consistono in strati di breccia a struttura massiva connessi a meccanismi deposizionali da caduta (airfall) e/o da debris flow, separati da livelli di tufo legati a fenomeni di base surge. i tufi grigi di oricola scalo sono costituiti essenzialmente da tufi cineritici grigi a lapilli, con laminazione incrociata da surge, e da tufi grigi a lapilli con struttura massiva da pyroclastic flow. i soprastanti tufi rossi di s. giovanni presentano, invece, uno spessore ed un’estensione areale maggiore di quella dei tufi grigi sottostanti. l’unità è prevalentemente formata da tufi rossi a lapilli, con strutture dunari o a laminazione parallela da surge e caduta (airfall). dopo la sedimentazione lacustre e alla fine degli episodi vulcanici, il territorio esaminato è stato interessato da un’intensa dinamica fluviale. questa ha portato alla sedimentazione, nel settore centro-meridionale ed orientale della conca, di estesi depositi alluvionali riconducibili ad eventi deposizionali differenti. lo studio lito-morfo-stratigrafico di questi depositi fluviali, integrato con diverse datazioni radiometriche, ha consentito una loro distinzione in quattro unità (ghiaie, sabbie e limi dei prati, conglomerati del fosso fioio, ghiaie, sabbie e limi dell’immagine, ghiaie, sabbie e limi del fiume turano) incastrate progressivamente le une nelle altre e di età variabile tra il pleistocene medio finale e l’attuale. all’interno dell’unità alluvionale riferibile al pleistocene medio finale è incassato un deposito carbonatico di origine continentale. si tratta di un orizzonte calcareo (calcareous tufa), datato a circa 46.000 ± 6.000 anni bp, che origina, in corrispondenza del settore meridionale della conca (fonte bosco), un corpo sedimentario di poche centinaia di metri di lunghezza e di 1,5 m di spessore massimo. per quanto riguarda le fasi deposizionali più recenti, particolarmente significativi si sono rivelati gli studio stratigrafici condotti sul conoide del fosso luisa (camerata nuova) e la datazione radiometrica di un orizzonte colluviale situato all’interno della sua porzione superiore. tale datazione, fornendo un’età calibrata di 3.550-3.400 anni bp, ha permesso una scansione temporale di alcuni eventi sedimentari ed erosivi che hanno caratterizzato la parte alta del conoide nell’olocene finale. abstract: d’orefice m. et al., quaternary geomorphological evolution of carsoli intermontane basin (l’aquila, italy). (it issn 03943356, 2010). in the present work the results of a geological and geomorphological study are presented. the study has been carried out in the carsoli intermontane basin (aq), a wide depression of tectonic origin, located between abruzzo and lazio regions, at the boundary of two different palaeogeographic domains, separated by the “olevano-antrodoco” tectonic line. the carsoli basin is filled with a continental sedimentary succession of considerable thickness and extent, which has been classified into several lithostratigraphic units, mainly on the basis of their lithological, morphological and geochronological characteristics. the oldest continental sediments outcropping within the study area are of lacustrine origin (bosco di oricola silts, clays and sands). these sediments, whose deposition has probably occurred in the lower – middle pleistocene, are characterized by a maximum thickness of about 200 m. they are widespread in the north-western and central parts of the basin (bosco di oricola) and are locally present on the eastern edge of the basin. the lacustrine deposits are cut across by an ancient sub-horizontal erosion surface, and at present, only some remnants remain. the lacustrine sediments are covered, on the north-eastern edge of the basin, by coarse fluvial sediments suspended on the present plain, originally deposited by the paleo-turano river (madonna delle grazie gravels). in the central-western and southern part of the study area, a significant sequence of local volcanic deposits, dated around 530 – 540 kyears bp, outcrops. the volcanic sequence abruptly begins from an articulated erosive surface shaped in lacustrine deposits and meso-cenozoic carbonatic bedrock. three main pyroclastic units are distinguished in the following members: 1) oricola scalo opeil quaternario italian journal of quaternary sciences 23(1), 2010 55-74 56 m. d’orefice et al. 1. introduzione la conca intermontana di carsoli (aq) riveste un particolare interesse nell’ambito della geologia del quaternario e della geomorfologia, in quanto: i) è colmata da un’articolata successione di sedimenti continentali di rilevante spessore ed estensione; ii) è sede di un peculiare vulcanismo monogenico locale medio-pleistocenico. lo scopo del presente lavoro è quello di delineare le principali tappe morfoevolutive che hanno caratterizzato la conca di carsoli nel corso del quaternario mediante l’utilizzo di dati litostratigrafici, geomorfologici e geocronologici, acquisiti nell’ambito di diverse ricerche condotte a partire dalla fine degli anni ’90. i dati litostratigrafici e geomorfologici inerenti i depositi continentali sono stati in gran parte tratti dai rilevamenti alla scala 1:10.000, effettuati nell’ambito della realizzazione del foglio geomorfologico 367 “tagliacozzo” (apat servizio geologico d’italia, 2009; chiarini et alii, 2009). considerata la rarità e la discontinuità degli affioramenti dei depositi quaternari, i rilevamenti di campagna sono stati integrati con dati ricavati sia da sondaggi geognostici già esistenti, sia da nuovi sondaggi elettrici verticali (s ervizio g eologico nazionale, 1998), sondaggi meccanici a carotaggio continuo (servizio geologico nazionale, 2000), trincee a mano e perforazioni realizzate mediante trivella manuale. le informazioni litostratigrafiche e tettoniche relative al substrato marino, invece, sono state desunte dal corrispondente foglio geologico “tagliacozzo” (servizio geologico d’italia, 2005; compagnoni et alii, 2005) e in parte integrate dai rilevamenti originali di alcuni autori del presente lavoro. il quadro litostratigrafico è stato arricchito con dati geocronologici desunti da diverse determinazioni isotopiche, riportate oltre che in bosi et alii (1991), in lavori precedenti svolti anche da alcuni autori di questa nota (barbieri et alii, 1998; d’orefice et alii, 2006; dramis et alii, 2008). 2. studi precedenti i primi lavori geomorfologici che hanno interessato l’area in studio sono quelli dell’elvetico bieler-chatelan (1928, 1929, 1930, 1931), il quale nelle sue numerose pubblicazioni sostiene che molte forme e depositi ivi presenti siano stati originati da un vasto ghiacciaio “polisintetico”, che scendendo lungo le cinque valli confluenti nella conca di carsoli, superava la stessa, per poi proseguire con due lingue nelle valli dell’aniene e del turano. tale ipotesi viene prontamente contestata da gortani (1930a, 1930b, 1931) e qualche anno dopo anche suter (1934, 1939) si convince della scarsa veridicità delle affermazioni dello studioso svizzero. con la pubblicazione del foglio 145 “avezzano” (regio ufficio geologico, 1934), privo tra l’altro di note illustrative, viene delineato un primo quadro geologico generale dell’area. in questo foglio vengono cartografate, su gran parte del fondo della conca, “alluvioni terrazzate del quaternario recente”, mentre lungo i bordi della depressione sono state rappresentate “conoidi abbandonate” e “detriti di falda”. solamente al centro della conca appaiono dei depositi vulcanici, descritti come “tufi più o meno cementati”. successivamente, in uno studio geomorfologico di carattere regionale, demangeot (1965) ipotizza l’origine della depressione per fenomeni carsici al di sotto della copertura “molassica”. egli, inoltre, in accordo con segre (1953), presuppone che lo svuotamento dell’antico lago di carsoli sia avvenuto progressivamente attraverso l’escavazione della forra del fosso bagnatore, indotta da una ripresa dell’attività tettonica nel settore compreso tra riofreddo ed arsoli. di filippo & toro (1979), nell’ambito d’indagini gravimetriche atte ad ottenere dati sull’andamento strutturale profondo dei m.ti simbruini, hanno evidenziato un minimo gravimetrico nella conca di carsoli, che imputano alla bassa densità degli “estesi e potenti” sedimenti lacustri ivi affioranti. raffy (1979) accentra la sua attenzione su un ning–vent breccias, 2) oricola scalo grey tuffs, 3) s. giovanni red tuffs. only the last two units widely outcrops in the study area. the oricola scalo opening-vent breccias are relative to the early opening phase of the conduit. they consist of a massive structure connected to the depositional mechanisms of airfall and/or debris flow, separated by tuff layers related to base surge phenomena. the oricola scalo grey tuffs unit mainly consists of grey ash-lapilli tuffs with surge cross-laminations, and grey lapilli tuffs with a massive structure of pyroclastic flow. the overlying s. giovanni red tuffs are characterized, instead, by a thickness and distribution greater than that of underlying grey tuffs. the unit is mainly composed of red lapilli tuffs, with dune structures or a parallel lamination of surge and airfall. after the lacustrine sedimentation and the volcanic episodes, the examined area underwent intense fluvial dynamics. this led to the sedimentation, in the central-southern and eastern part of the basin, of a sequence of alluvial deposits belonging to different depositional events. the morpho-litho-stratigraphic analysis of these fluvial deposits, in addition with radiometric ages, allowed for their classification into four units (prati gravels, sands and silts, fioio stream conglomerates, immagine gravels, sands and silts, turano river gravels, sands and silts) progressively embedded into each other and ranging in age between the late middle pleistocene and the present. entrenched in the late middle pleistocene alluvial unit, in the southern sector of the basin (fonte bosco), a few hundred meters long and 1.5 meters thick calcareous tufa layer, dated by u-series method at 46,000 ± 6,000 years bp outcrops. with regard to the most recent depositional phases, great relevance has to be ascribed to the stratigraphic study carried out on the fosso luisa fan (camerata nuova) and the radiometric dating of colluvial horizon, there present. this dating, providing a calibrated 14c age of 3,550-3,400 years bp, has allowed for a temporal definition of some sedimentary and erosive events that marked the upper part of the fan during the final part of holocene. parole chiave: geologia del quaternario, geomorfologia, bacini continentali intermontani, oricola-carsoli (l’aquila). keywords: quaternary geology, geomorphology, intermontane continental basins, oricola–carsoli (l’aquila). deposito fluviale molto grossolano, affiorante sulla collina calacorte (625 m s.l.m.), a sud di poggio cinolfo, e in base a considerazioni sull’energia del mezzo, correla questi depositi fluviali con quelli ubicati più a valle, a nord di turania, dove essi però superano gli 800 m di quota. la differenza altimetrica viene giustificata, dall’autrice, mediante la presenza, tra vivaro romano e poggio cinolfo, di faglie dirette a direzione appenninica ed antiappenninica, che ribassano i depositi fluviali di calacorte. ciò, unito ad altre considerazioni, induce la raffy ad ipotizzare un’origine tettonica della depressione, la quale a suo avviso è stata sede di un’unica sedimentazione lacustre, prodottasi in condizioni climatiche umide e conclusasi con un episodio vulcanico. l’abbondanza delle vulcaniti e le dimensioni dei minerali in esse contenuti, portano l’autrice ad escludere una loro origine lontana e a supporre una provenienza di questi prodotti da condotti vulcanici locali, analoghi a quelli di m. autore e della valle dell’aniene. in uno schema morfologico regionale raffy (1979, 1981/82) attribuisce i sedimenti lacustri, compresi i depositi vulcanici, al pleistocene medio. successivamente, informazioni a carattere generale vengono fornite dalla “carta delle litofacies del lazio-abruzzo” (accordi et alii, 1986), dove, data la scala 1:250.000, gli unici sedimenti continentali cartografati, nell’area in esame, sono costituiti da “depositi argillosi-sabbiosi contenenti molluschi lacustri stratigraficamente poco significativi (plio-pleistocene indifferenziato)”. detti (1988), nell’ambito di una tesi di laurea, ha eseguito un rilevamento alla scala 1:10.000 dell’intero bacino, finalizzato a delinearne l’evoluzione geologica plio-pleistocenica. la successione continentale affiorante viene suddivisa nelle seguenti formazioni progressivamente incassate le une nelle altre: “sabbie e limi di oricola”, “vulcaniti di civita”, “tufiti di s. giovanni”, “limi e sabbie vulcaniche dei prati”, “conglomerati di fontanelle brecciaro”, “ghiaie di pisciarello”, “ghiaie di calacorte”, “sabbie e ghiaie della piana”, “ghiaie del macerone”, “detriti di falda e coltri colluviali”. le “sabbie e limi di oricola” sono state attribuite al pleistocene inferiore finale – pleistocene medio, le “vulcaniti di civita” e i “tufi di s. giovanni” ipoteticamente a 600.000 anni dal presente, la successione compresa tra i “limi e sabbie vulcaniche dei prati” e le “ghiaie di calacorte” al pleistocene medio-superiore e i restanti depositi all’olocene. a partire dagli anni ’90, una certa attenzione viene riservata ai prodotti vulcanici affioranti in questa zona, nei cui riguardi prima bosi et alii (1991) e poi bosi & locardi (1991/2) ipotizzano un’origine locale, sulla scorta di argomentazioni geologiche e per la prima volta geochimiche. colica et alii (1995), nell’ambito di uno studio di geologia del quaternario esteso a buona parte della conca di carsoli, individuano cinque unità morfo-litopedo-stratigrafiche che rappresentano su una carta geologica schematica alla scala 1:42.000. tali unità, la cui attribuzione cronologica è stata effettuata dagli autori essenzialmente in base alle caratteristiche litologiche ed al grado di sviluppo pedogenetico dei suoli, sono costituite da “depositi lacustri del pleistocene inferiore-pleistocene medio”, da “vulcaniti e tufiti di oricola, del pleistocene medio” di origine locale e da 57evoluzione geomorfologica quaternaria ... tre corpi sedimentari (“unità q3”, “unità q2” e “unità q1”) formati da depositi alluvionali compresi tra un generico pleistocene e l’olocene. questi autori, infine, in base ad una correlazione tra lineazioni, unità morfolito-stratigrafiche e tipologia del reticolo idrografico, ipotizzano un’influenza neotettonica nell’evoluzione quaternaria della conca. una successiva pubblicazione (lorenzoni et alii, 1995) è dedicata alla “carta dei suoli della conca intramontana tra oricola e carsoli (provincia dell’aquila)”. tra la fine degli anni ’90 e i primi anni del secolo attuale, grazie ai nuovi dati provenienti dal rilevamento del foglio geologico e geomorfologico 367 “tagliacozzo” in scala 1:50.000 (servizio geologico d’italia, 2005; compagnoni et alii, 2005; apat servizio geologico d’italia, 2009; chiarini et alii, 2009), vengono realizzati nuovi studi a carattere geomorfologico, vulcanologico, petro-mineralogico e geochimico (barbieri et alii, 1997, 2000; d’orefice & graciotti, 2005; d’orefice et alii, 2006; dramis et alii, 2008). 3. inquadramento geografico e geologico la conca intermontana di carsoli è situata nel settore occidentale dell’appennino centrale, al confine tra le regioni abruzzo e lazio, ed è compresa interamente all’interno del bacino idrografico del fiume turano (fig. 1). si tratta di un’ampia depressione chiusa, sede di un antico e vasto bacino lacustre, in cui sono andati a confluire forti spessori di depositi continentali, costituiti essenzialmente da sedimenti lacustri ed in minor misura da depositi fluviali strictu sensu, di conoide alluvionale e di versante. sotto il profilo fisiografico la parte più depressa della conca di carsoli è contraddistinta da un ampia superficie di circa 40 km2 di estensione, sviluppata pressappoco tra la quota massima di 750 m s.l.m. (estremo settore meridionale) e la quota minima di 565 m s.l.m. (estremo settore settentrionale). tale superficie, caratterizzata da un perimetro sinuoso sul lato orientale e meridionale della conca e più regolare su quello occidentale e settentrionale, presenta in pianta una forma pressappoco ellittica, con asse maggiore, a direzione nno-sse, lungo circa 12 km ed asse minore, ortogonale al primo, di circa 6 km di lunghezza (fig. 1). la conca è profondamente incassata nei rilievi circostanti, i quali si affacciano sulla stessa con quote che raggiungono i 1.200 m circa s.l.m. in corrispondenza del sua porzione più meridionale. complessivamente il fondo della depressione può essere considerato sub-pianeggiante, ma ad un esame più accurato questo risulta abbastanza irregolare. esso, infatti, è caratterizzato da un microrilievo costituito da una serie di collinette che si ergono all’incirca dai 20 ai 40 metri al di sopra delle piane alluvionali attuali del f. turano e del reticolo idrografico ad esso affluente. in linea di massima possono essere distinte due principali zone collinari, separate da una stretta area pianeggiante, a forma di “z”, percorsa dai fossi fioio e cammarano e dal f. turano (fig. 1). il f. turano rappresenta l’asta principale, che percorre la parte più depressa della conca con un tracciato caratterizzato da repentini cambi di direzione. esso, infatti, in prossimità del centro abitato di carsoli devia sedimenti calcarei e calcareomarnosi miocenici (fig. 2). il lato nord-occidentale della depressione è delimitato da una serie di rilievi meno elevati e fittamente boscati, la cui continuità è interrotta verso oriente dalla valle del f. turano (fig. 1). questi rilievi sono formati da torbiditi prevalentemente arenacee ed arenaceo-pelitiche deposte nell’avanfossa messiniana (fig. 2). i rilievi modellati sui sedimenti torbiditici messiniani proseguono verso ne, bordando il lato nord-orientale della conca. su di essi sono ubicati i paesi di collalto sabino (980 m s.l.m.), poggio cinolfo (713 m s.l.m.) e carsoli (650 m s.l.m.) (figg. 1 e 2). la conca è chiusa, sul suo lato sud-orientale, da una serie di dorsali dall’andamento prevalentemente appenninico. si tratta dei rilievi carbonatici di età cretacico-miocenica, appartenenti alle propaggini nord-occidentali dei monti simbruini, alla cui base è arroccato il paese di pereto (878 m s.l.m.) (figg. 1 e 2). sempre ai monti simbruini nord-occidentali appartiene il rilievo su cui sorge oricola (810 m s.l.m.), che, con andamento nno-sse, chiude il lato sud-occidentale della conca di carsoli (figg. 1 e 2). la parte più meridionale della depressione, si va ad incuneare all’interno dei rilievi simbruini, restringendosi, fino a chiudersi, in corrispondenza di camerata nuova (810 m s.l.m.). dal punto di vista paleogeografico la conca di carsoli è situata in prossimità del contatto tra due differenti domini meso-cenozoici. ad est ed a sud-est le strutture dei rilievi calcarei dei monti simbruini sono, infatti, in facies di piattaforma interna laziale-abruzzese e risultano allineate prevalentemente in direzione nose, mentre ad ovest i litotipi appartenenti alle strutture calcaree e calcareo-marnose dei monti sabini sono in facies sabina di transizione tra la piattaforma carbonatica ed il bacino umbro-marchigiano ed hanno un andamento meridiano (fig. 2). questi due domini paleogeografici sono separati da un tratto della linea tettonica “olèvano-antrodoco” (damiani, 1984; cavinato et alii, 1986; cosentino & parotto, 1991; cipollari & cosentino, 1992), “ancona-anzio” auctt. (castellarin et alii, 1978), che con andamento circa n-s borda il piede dei monti sabini orientali, originando, a seguito dei fenomeni erosivi, una netta rottura di pendio (fig. 1). tra i due domini sono interposti tettonicamente i depositi silicoclastici, terrigeni, dell’avanfossa messiniana. le vicende tettoniche che hanno interessato l’area sono inquadrabili all’interno di un contesto più generale che ha riguardato l’appennino laziale-abruzzese. nel messiniano questo settore appenninico viene completamente implicato nelle fasi compressive dell’o58 bruscamente di circa 50° verso so per entrare nella conca omonima (figg. 1 e 2). dopo un altro rapido cambiamento di direzione di circa 70°, in corrispondenza della confluenza con il fosso cammarano, suo affluente di sinistra, il turano assume una direzione appenninica, che manterrà sino alla confluenza con il fosso carcarone, altro suo affluente di sinistra. da questo punto in poi il fiume devia di circa 40° verso nord ed esce dalla depressione. il reticolo ad esso affluente è contraddistinto da densità di drenaggio, grado di gerarchizzazione e pattern differenti da settore a settore della conca, in funzione dei litotipi affioranti. in particolare, nel settore centro-occidentale (bosco di oricola), il reticolo idrografico è ben organizzato secondo un pattern sub-dendritico, con direzione prevalente delle aste principali no-se e nne-sso e una densità di drenaggio elevata. nel settore settentrionale e nord-orientale del bacino in esame (tra poggio cinolfo e villa romana) il reticolo idrografico mostra un pattern dendritico, ben gerarchizzato, con direzione prevalente delle aste neso e in subordine e-o. i quadranti meridionali della depressione sono invece contraddistinti da un reticolo sub-parallelo, poco o nulla gerarchizzato e con bassa densità di drenaggio, ad andamento da ono-ese a nno-sse. il lato occidentale della conca è demarcato da un allineamento di monti a direzione n-s, su cui sorgono i paesi di vallinfreda e vivaro romano (fig. 1). tali rilievi, che raggiungono i 1.000 m di altezza, appartengono alle dorsali più orientali dei monti sabini, costituite da fig. 1 rilievo ombreggiato della conca di carsoli ricavato dal modello digitale del terreno con risoluzione di 20 m. nel riquadro, localizzazione dell’area in studio. shaded relief of the carsoli basin obtained from a 20 m resolution digital terrain model. the study area is enclosed in the box. m. d’orefice et al. 59 rogenesi appenninica, che hanno determinato piegamenti ed accavallamenti vergenti verso ne, come ad esempio il fronte dei simbruini. alla fase tettonica messiniana fa seguito, nel pliocene inferiore, una nuova fase, che determina la sovrapposizione, verso est, del dominio di transizione su quello di piattaforma lungo la citata linea “olevano antrodoco”. questa linea avrebbe, quindi, le caratteristiche di un elemento tettonico fuori sequenza rispetto alla generale successione temporale e spaziale con cui si sono sviluppati i principali fronti di sovrascorrimento della catena appenninica, in progressiva migrazione verso est (cipollari & cosentino, 1992). la catena appena strutturata è stata in seguito interessata da un’intensa fase tettonica distensiva plioquaternaria, che ha ribassato estesi settori della catena stessa, mediante la genesi di numerose faglie dirette e la riattivazione di rampe di thrust come faglie normali a basso angolo; è questo il caso dell’importante faglia del fosso fioio (damiani, 1990; compagnoni et alii, 1993) che, con un decorso pressoché parallelo alla valle omonima (fig. 2), separa le dolomie e i calcari del cretacico inferiore a ne, dai calcari del cretacico superiore – miocene a so, con un rigetto reale di circa 1.500 m. per quanto concerne l’evoluzione tettonica della conca di carsoli, scarsi sono gli elementi e le evidenze di campagna che possano consentire una ricostruzione abbastanza attendibile, come anche rare sono le pubblicazioni su tale argomento riguardanti quest’area e le zone ad essa limitrofe. tra queste può essere citato il lavoro di cavinato et alii (1986), che analizza le caratteristiche strutturali di un’ampia fascia (circa 30 km) a cavallo del settore centrale della linea “olévano antrodoco”, e quello di ambrosetti et alii (1987), finalizzato alla realizzazione della “carta neotettonica d’italia”. nel lavoro di cavinato et alii (1986), in cui almeno 15 stazioni di misura per l’analisi strutturale ricadono lungo il perimetro della fig. 2 schema geologico dell’intera conca di carsoli (modificato da d’orefice & graciotti, 2005). legenda: 1) ghiaie sabbie e limi del fiume turano flt e depositi colluviali (tardoolocene – attuale); 2) ghiaie, sabbie e limi dell’immagine – fli (12,5-11,9 ÷ 4,1-3,9 ka cal bc; tardoglaciale – olocene iniziale); 3) conglomerati del fosso fioio cof (pleistocene superiore); 4) tufi calcarei di fonte bosco – cfb (46 ± 6 ka bp, metodo u/th; pleistocene superiore); 5) ghiaie, sabbie e limi dei prati – flp (pleistocene medio finale); 6) depositi piroclastici indifferenziati (531 ÷ 540 ka bp, metodo 40ar/39ar e rb/sr; pleistocene medio); 7) ghiaie della madonna delle grazie – flg (pleistocene medio iniziale); 8) limi, argille e sabbie del bosco di oricola – lao (pleistocene inferiore pleistocene medio iniziale); 9) sedimenti terrigeni: torbiditi silicoclastiche e marne a orbulina (miocene superiore); 10) sedimenti carbonatici in facies sabina di transizione (miocene inferiore – medio); 11) sedimenti carbonatici in facies laziale-abruzzese di piattaforma (cretacico inferiore – miocene medio); 12) sovrascorrimento (tratteggiato: non affiorante); 13) faglia diretta (tratteggiata: non affiorante); 14) datazioni radiometriche. geological scheme of the full carsoli basin (modified from d’orefice & graciotti, 2005). legend: 1) turano river silts, clays and sands – flt and colluvial deposits (late holocene – present); 2) immagine gravels, sands and silts – fli (12.5-11.9 ÷ 4.1-3.9 cal ka bc; late glacial – early holocene); 3) fioio stream conglomerates cof (upper pleistocene); 4) fonte bosco calcareous tufa – cfb (46 ± 6 ka bp, u/th method; upper pleistocene); 5) prati gravels, sands and silts – flp (late middle pleistocene); 6) undifferentiated pyroclastic deposits (531 ÷ 540 ka bp, 40ar/39ar and rb/sr methods; middle pleistocene); 7) madonna delle grazie gravels flg (early middle pleistocene); 8) bosco di oricola silts, clays and sands – lao (lower pleistocene – early middle pleistocene); 9) terrigenous sediments: siliciclastic turbidites and orbulina marls (upper miocene); 10) transitional «sabina» facies carbonatic sediments (lowermiddle miocene); 11) «laziale-abruzzese» platform facies carbonatic sediments (lower cretaceous – middle miocene); 12) overthrust (hatched: not outcropping); 13) normal fault (hatched: not outcropping); 14) radiometric dating. evoluzione geomorfologica quaternaria ... 60 conca, sono state individuate quattro fasi tettoniche, di cui tre compressive, avvenute tra il tortonianomessiniano e il pliocene inferiore, ed una distensiva tra il pliocene medio e l’attuale. la prima fase compressiva è contraddistinta da sistemi coniugati di faglie inverse a direzione appenninica e localmente da sistemi trascorrenti. a questa fase segue un episodio distensivo, che ha generato sistemi di faglie dirette con direzione nose. la seconda fase compressiva ha causato la formazione di strutture plicative ad asse prevalente n-s e sistemi coniugati di faglie inverse n20°o, a cui sono associate faglie di trascinamento orientate mediamente n70°e. la terza fase compressiva, meno evidente e diffusa delle precedenti, ha originato sistemi coniugati inversi e pieghe con cerniere ne-so. la fase distensiva finale è rappresentata da sistemi coniugati di faglie dirette e faglie verticali n-s ed e-o, che dislocano chiaramente le strutture compressive preesistenti e, in particolare, la linea “olevano antrodoco”. nella “carta neotettonica d’italia” (ambrosetti et et alii, 1987), la conca di carsoli risulta caratterizzata, a partire dal pliocene inferiore e medio, prima da un sollevamento, poi nel pliocene medio e superiore da un abbassamento, seguito da una risalita; nel pleistocene inferiore si sarebbe nuovamente verificato un abbassamento, seguito a partire dal pleistocene medio da un sollevamento. prospezioni geofisiche, realizzate dal servizio geologico nazionale (1998) su tutta la depressione per ricostruire l’andamento nel sottosuolo del substrato carbonatico e torbiditico, hanno evidenziato la presenza di diverse linee di discontinuità che isolano il bedrock secondo blocchi. questi sono delimitati da linee di discontinuità principali che, con orientamento n-s e nno-sso, interessano l’intero sottosuolo della conca e da discontinuità di lunghezza minore allineate in direzione ono-ese, ne-so, no-se e e-o. la disposizione relativa dei vari blocchi dà luogo ad alti e bassi strutturali al di sotto della successione continentale che ricopre in discordanza il substrato. in corrispondenza del bosco di oricola è stata registrata la massima profondità del tetto del substrato carbonatico, con quote che scendono al di sotto del livello del mare, fino a raggiungere la profondità di oltre 650 m dal piano campagna. 4. litostratigrafia del substrato pre-quaternario le rocce più antiche della successione carbonatica di piattaforma, risalgono agli inizi del cretacico inferiore e si rinvengono esclusivamente lungo la valle del fosso fioio, dove affiorano, per diverse centinaia di metri di spessore, alternanze calcareo-dolomitiche passanti verso l’alto a dolomie (“dolomie del fosso fioio”). in continuità stratigrafica seguono i “calcari a requienidi” dell’aptiano-cenomaniano, formati da calcari, calcari dolomitici e dolomie, e i “calcari a radiolitidi” del cretacico superiore. nella parte più occidentale dei m.ti simbruini (tra arsoli, pereto e camerata nuova), la successione cretacica di piattaforma carbonatica si chiude con i “calcari saccaroidi ad orbitoidi” (?campaniano p.p. – maastrichtiano p.p.), formati da calcari di spessore modesto intensamente ricristallizzati. dopo la cosiddetta “lacuna paleogenica”, la sedimentazione carbonatica continua con la deposizione delle “calcareniti arancioni ad echinidi” del (?)burdigaliano langhiano p.p.. tale unità, in genere paraconcordante sui calcari del cretacico superiore, affiora con spessori esigui in corrispondenza dei rilievi simbruini che si affacciano sulla conca di carsoli. in successione stratigrafica sulle “calcareniti arancioni ad echinidi” si rinviene la formazione dei “calcari a briozoi e litotamni” (langhiano p.p. – serravalliano p.p.) costituita da calcareniti bioclastiche biancastre ben stratificate. questa formazione, con uno spessore di un centinaio di metri, occupa gran parte del settore sud-orientale, meridionale e sud-occidentale dell’area in esame e presenta dei caratteri parzialmente diversi nelle strutture laziali-abruzzesi e in quelle sabine. della successione sabina di transizione nell’area in studio affiora solo la “formazione di guadagnolo” (aquitaniano p.p. – langhiano (serravalliano p.p.)), costituita da marne, calcari marnosi e livelli calcarenitici, con lenti di selce ed abbondanti spicole di spugna. questa formazione, presente esclusivamente lungo il margine occidentale della conca di carsoli, passa gradualmente a quella sopraccitata dei “calcari a briozoi e litotamni”. al di sopra dei calcari miocenici si rinvengono termini terrigeni appartenenti alla formazione delle “marne a orbulina” del serravalliano p.p. – messiniano inferiore, che testimoniano l’iniziale impostazione del bacino di avanfossa del liri-tagliacozzo. questa formazione, costituita da calcareniti, calcari marnosi, marne e argille, affiora, in fasce strette ed allungate di modesto spessore, solo lungo il margine occidentale della conca. alle marne a orbulina seguono stratigraficamente torbiditi silicoclastiche che avrebbero colmato, nel messiniano inferiore, il bacino di avanfossa sopra riportato (“unità arenaceo-pelitica del liri-tagliacozzo”). nell’area in studio le torbiditi sono prevalentemente arenacee, in strati molto spessi, con rare intercalazioni di litofacies arenaceo-pelitiche e pelitico-arenacee in strati sottili e molto sottili. lungo il bordo nord-orientale della conca, tra poggio cinolfo e carsoli, le arenarie torbiditiche sono caratterizzate da intercalazioni di livelli conglomeratici poligenici e di calcareniti grossolane, nonché dalla presenza di olistoliti calcarei. le torbiditi affiorano essenzialmente lungo il margine settentrionale e nord-orientale della conca, nei dintorni di riofreddo e a nord di oricola (fig. 2). in corrispondenza del settore nord-orientale dei m.ti simbruini, al di fuori dell’area in studio, la sedimentazione terrigena ha dato invece luogo, nel tortoniano messiniano inferiore, alla formazione di spessi depositi poligenici, prevalentemente psefitici, d’origine marina, denominati “brecce della renga” (devoto 1967a; 1967b). 5. litostratigrafia delle successioni continentali dopo una generale emersione, i prodotti originati dallo smantellamento dei rilievi meso-cenozoici, per opera degli agenti esogeni, hanno dato luogo ad una serie di depositi continentali quaternari, che si sono andati ad accumulare all’interno della depressione di carsoli. lo spessore di questi depositi è elevato, come m. d’orefice et al. evidenziato dalle indagini gravimetriche effettuate da di filippo & toro (1979) nel settore sudorientale della conca stessa; più precisamente esso può abbondantemente superare i 200 m circa, sulla scorta dei dati ricavati dalle prospezioni geofisiche realizzate dal servizio geologico nazionale (1998). i depositi continentali quaternari individuati nell’area in esame sono stati distinti in diverse unità, essenzialmente sulla base delle loro caratteristiche litostratigrafiche e delle morfologie ad essi associate (fig. 3). in quest’ambito non si è fatto ricorso alle unità sintemiche, poiché il riconoscimento di superfici di discontinuità significative e dimostrabili si è rivelato molto difficoltoso a causa della rarità degli affioramenti. complessivamente, nell’ambito della successione continentale sono stati individuate le seguenti formazioni, elencate a partire dalle più antiche: • limi, argille e sabbie del bosco di oricola (lao). • ghiaie della madonna delle grazie (flg). • vulcaniti della conca di carsoli: membro delle brecce d’apertura di oricola scalo (bao). membro dei tufi grigi di oricola scalo (tgo). membro dei tufi rossi di s. giovanni (trg). • ghiaie, sabbie e limi dei prati (flp). • tufi calcarei di fonte bosco (cfb). • conglomerati del fosso fioio (cof). • ghiaie, sabbie e limi dell’immagine (fli). • ghiaie, sabbie e limi del fiume turano (flt). • colluvi e detriti di versante (cdv). 5.1. limi, argille e sabbie del bosco di oricola (lao) i limi, argille e sabbie del bosco di oricola costituiscono i depositi continentali più antichi presenti all’interno della conca (fig. 3). questi sedimenti, confinati unicamente nel bacino attuale, affiorano in circa il 50% dell’area in esame, rinvenendosi con una certa continuità in tutto il settore nordoccidentale e in parte centrale della stessa (bosco di oricola) (fig. 2). lembi isolati si rinvengono a col farolo e zone limitrofe, lungo il fosso rientro, a nord di colle s. vito e in corrispondenza del bordo orientale e nord-orientale della depressione (convento di s. francesco e dintorni). nel settore nord-occidentale della conca la quota massima di affioramento è di 637 m, mentre la quota minima è di 575 m s.l.m., invece a col farolo la formazione affiora tra 658 m e 595 m s.l.m. comunque, è lungo il margine orientale e nord-orientale che essa raggiunge le altezze più elevate, come ad esempio nell’area del convento di s. francesco. partendo da questa località e procedendo verso ne, le quote massime di affioramento variano, infatti, da 630 m a 730 m circa, mentre gli spessori massimi si mantengono costantemente intorno ai 20-30 m. i depositi in esame si presentano ben stratificati e contraddistinti da alternanze di strati argilloso-limosi di colore grigio-azzurro e sabbioso-limosi di colore giallognolo; quest’ultimi sono più frequenti nella parte più alta della formazione, evidenziando un trend di tipo coarsening-upward (cu). gli strati, di spessore variabile da qualche centimetro ad un metro, hanno una forma tabulare alla scala dell’affioramento e sono delimitati da superfici piane e parallele (fig. 4). internamente essi sono caratterizzati da una sottile laminazione prevalentemente di tipo piano-parallela. gli strati sabbioso-limosi sono interessati da diffuse screziature ocra legate a fenomeni di ossidazione dei minerali ferrosi. frequentemente il passaggio da strati sabbioso-limosi a sottostanti strati argilloso-limosi è contrassegnato da patine di alterazione limonitiche e da tasche e lobi da carico. queste strutture da carico fanno sì che il limite tra uno strato e l’altro a volte sia leggermente ondulato. 61 fig. 3 ricostruzione schematica dei rapporti morfo-litostratigrafici tra le varie unità sedimentarie continentali individuate all’interno della conca di carsoli (non in scala). lao = limi, argille e sabbie del bosco di oricola; flg = ghiaie della madonna delle grazie; bao = brecce d’apertura di oricola scalo; tgo = tufi grigi di oricola scalo; trg = tufi rossi di s. giovanni; flp = ghiaie, sabbie e limi dei prati; cfb = tufi calcarei di fonte bosco; cof = conglomerati del fosso fioio; fli = ghiaie, sabbie e limi dell’immagine; flt = ghiaie, sabbie e limi del fiume turano. schematic reconstruction of the morpho-lithostratigraphic relationships between the different continental sedimentary units recognized in the carsoli basin (not in scale). lao = bosco di oricola silts, clays and sands; flg = madonna delle grazie gravels; bao = oricola scalo opening-vent breccias; tgo = oricola scalo grey tuffs; trg = s. giovanni red tuffs; flp = prati gravels, sands and silts; cfb = fonte bosco calcareous tufa; cof = fioio stream conglomerates; fli = immagine gravels, sands and silts; flt = turano river gravels, sands and silts fig. 4 limi, argille e sabbie del bosco di oricola (lao). sezione artificiale ubicata in prossimità della pendici del versante settentrionale di col farolo. i sedimenti, di origine lacustre, si presentano ben stratificati e inclinati di circa 20° verso sse. bosco di oricola silts, clays and sands (lao). artificial section located near the base of the col farolo northern slope. the lacustrine sediments are well stratified and inclined by about 20° to sse. evoluzione geomorfologica quaternaria ... nei livelli più argillosi, a luoghi, si individuano valve giovanili e frammenti di ostracodi di acqua dolce, appartenenti al genere ilyocypris e candona (gliozzi, comunicazione personale); si tratta di un’ostracofauna tipicamente ipoalina, propria di un ambiente lacustre o palustre, che non fornisce alcuna indicazione di età. sempre negli strati più argillosi si rinvengono gusci, in alcuni casi ben conservati, di gasteropodi, appartenenti ai generi cernuella cfr. virgata, cepea sp., helix sp., vallonia cfr. pulchella e dubitativamente limnea. tale malacofauna è costituita da tutte forme terrestri, se si esclude la presenza, peraltro dubbia, di limnea, genere tipico di acque stagnanti. i gasteropodi riconosciuti fanno presumere l’esistenza di un ambiente aperto, tipo prato, con bassa vegetazione. le malacofaune rinvenute, comunque, essendo banali, non consentono nessuna determinazione di età relativa. per quanto riguarda il contenuto pollinico della parte più argillosa di questi sedimenti, su tre campioni analizzati solo due hanno restituito rarissimi palinomorfi appartenenti a due soli taxa erbacei: artemisia e liliiflorae (sadori, 2005). un orizzonte lignitifero di modesto spessore è stato intercettato, ad una profondità di circa 100 m dal p.c., in un sondaggio realizzato molti anni fa all’interno del polverificio ex stacchini sud, in località rostere (quota boccapozzo 615 m s.l.m.). la frazione più sabbiosa è caratterizzata da una gran quantità di granuli di natura silicoclastica, mentre sono del tutto assenti livelli di origine piroclastica. le analisi diffrattometriche effettuate su alcuni campioni, infatti, hanno rilevato una composizione mineralogica costituita dai seguenti minerali, elencati in ordine di abbondanza: quarzo, plagioclasio, mica, clorite, caolinite e k-feldspato. la composizione mineralogica evidenziata, rivela una provenienza di questi depositi prevalentemente dall’erosione dei litotipi terrigeni messiniani, in gran parte affioranti nel settore settentrionale della conca di carsoli e a nord di essa, lungo la medio-alta valle del turano. lo spessore di questi depositi, secondo i dati provenienti da alcune perforazioni realizzate soprattutto per scopi idrici, ed in base ad indagini geofisiche appositamente effettuate dal servizio geologico nazionale (1998), è variabile da pochi metri lungo i margini della piana, a più di 200 m nella zona depocentrale del bacino, situata in corrispondenza del bosco di oricola. il limite inferiore di questa unità è rappresentato da una superficie di discontinuità erosiva, attraverso la quale la formazione poggia in discordanza angolare sul substrato marino carbonatico e terrigeno. tale superficie, tracciabile lungo il bordo settentrionale, nord-orientale e orientale della conca di carsoli, aumenta sensibilmente e progressivamente di quota da col farolo verso le propaggini dei rilievi simbruini (da 650 a 675 m circa) e dal convento di s. francesco verso ne (da 600 a 700 m circa). alla sommità l’unità è delimitata da un’antica ed estesa superficie suborizzontale, coincidente con l’attuale piano topografico e discordante con la giacitura degli strati. tale superficie, di natura chiaramente erosiva, è inclinata di circa 1° verso nord-ovest. di questa superficie allo stato attuale rimangono solo alcuni lembi relitti tra le quote 620 m (bosco di oricola) e 658 m s.l.m. (col farolo), in conseguenza della sua incisione da parte di un reticolo idrografico subdendritico orientato prevalentemente in direzione no-se e nne-sso. nel complesso la stratificazione nel settore centrale della conca è suborizzontale, mentre lungo il margine centro-orientale e nord-orientale della stessa gli strati assumono inclinazioni di circa 10°-20° con immersioni variabili da sso a se (fig. 4). in alcuni affioramenti, ubicati in prossimità di col farolo, sono state osservate delle piccole dislocazioni tettoniche di carattere distensivo con rigetto di qualche metro. la presenza, lungo il bordo orientale e nord-orientale della conca, di strati più inclinati e di piccole faglie, unita a una quota più elevata delle superfici di discontinuità che delimitano questa formazione, inducono ad ipotizzare un sollevamento di questo settore. i caratteri tessiturali e granulometrici di questi depositi, le loro strutture sedimentarie, la continuità laterale degli strati, la geometria e la regolarità delle superfici di stratificazione, l’ostracofauna in essi presente, fanno pensare ad una sedimentazione in un mezzo a bassa energia. pertanto, sulla base di queste caratteristiche, peraltro uniformi in tutto il bacino sedimentario, e della distribuzione areale dei sedimenti, i depositi in questione possono essere attribuiti, in accordo con vari autori (segre, 1953; demangeot, 1965; raffy, 1979; accordi et alii, 1986; detti, 1988; colica et alii, 1995; compagnoni et alii, 2005; d’orefice & graciotti, 2005; chiarini et alii, 2009), ad un ambiente deposizionale lacustre. in un affioramento situato nel bosco di oricola è stato individuato un livello di modesto spessore costituito da sabbie gialle grossolane, sovrapposte, con contatto erosivo, a questa formazione. le sabbie, di natura silicoclastica e prive di minerali femici, sono caratterizzate da piccoli canali d’erosione e da una stratificazione incrociata ad alto angolo, che indica una paleocorrente diretta verso i quadranti settentrionali. alla sommità dei depositi lacustri, nelle aree suborizzontali preservate dall’azione degli attuali processi erosivi, colica et alii (1995) hanno individuato dei paleosuoli (alfisuoli a profilo a b c) con caratteristiche pedologiche di condizioni climatiche non attuali. questi paleosuoli, secondo il parere degli stessi autori, dal confronto con altri paleosuoli dell’italia centrale, potrebbero essere attribuiti al pleistocene superiore. in mancanza di precisi riferimenti crono-biostratigrafici, le età proposte per i depositi lacustri sono generiche e diverse. secondo raffy (1981/82) tali sedimenti sono attribuibili al pleistocene medio; accordi et alii (1986) e compagnoni et alii (2005) li indicano come (?)plio-pleistocenici, mentre secondo detti (1988), colica et alii (1995) e d’orefice & graciotti (2005) essi hanno un’età compresa tra il pleistocene inferiore ed il pleistocene medio. questi depositi, in ogni modo, sono più antichi dei sovrastanti prodotti vulcanici, datati intorno ai 530-540.000 anni dal presente (cfr par. 5.3.). 5.2. ghiaie della madonna delle grazie (flg) questa formazione affiora, tra 640 m e 580 m di quota s.l.m., lungo il bordo nord-orientale della conca di carsoli, e più precisamente tra il convento di s. francesco ed il margine settentrionale della conca stessa (località “cerretine”). piccoli affioramenti, non cartografabili, probabilmente correlabili con quelli prima citati, si rinvengono, tra 700 e 710 m di quota, sulle colline 62 m. d’orefice et al. immediatamente a nord-ovest di carsoli, ed in particolare sul versante destro della valle mura, che si immette in destra della valle del turano. nel complesso la formazione in esame è costituita prevalentemente da ghiaie eterometriche, da centimetriche a decimetriche ed in misura minore da blocchi, che in casi eccezionali superano il metro di diametro (fig. 5). a luoghi nel deposito grossolano s’intercalano piccole lenti limoso-argillose o livelli sabbiosi. in generale il deposito ghiaioso si presenta mal classato. le ghiaie e i blocchi sono in prevalenza costituiti da litotipi calcarei appartenenti alla serie locale di piattaforma carbonatica, da “brecce della renga” ed in minor misura da litotipi arenacei. nella maggior parte dei casi i blocchi sono arrotondati, di forma sferica e con un indice di sfericità e di arrotondamento medio-alto; le ghiaie sono, invece, caratterizzate da una forma da sferica a discoidale e da un indice di arrotondamento minore. sporadicamente s’individuano clasti contraddistinti da un’alterazione superficiale. la matrice è abbondante, essenzialmente sabbioso-limosa e di natura silicoclastica. al suo interno non sono stati rinvenuti minerali femici di origine piroclastica. nel complesso la tessitura è a supporto di clasti e solo raramente è a supporto di matrice. non è evidente una netta embricatura dei ciottoli, comunque, nei pochi casi in cui questa è osservabile, essa denota un andamento prevalente della paleocorrente verso i quadranti settentrionali. questa formazione raggiunge uno spessore massimo di circa 10 m tra il convento di s. francesco e la collina calacorte. le ghiaie della madonna dele grazie sono inferiormente a contatto diretto, tramite una irregolare superficie d’erosione, sia con le torbiditi arenacee alto-mioceniche, sia con i limi, argille e sabbie del bosco di oricola (fig. 3). il limite superiore dell’unità coincide, invece, con l’attuale superficie topografica. dal punto di vista morfostratigrafico questa formazione, allungata nella stessa direzione dell’attuale corso del f. turano e sospesa sulla sua odierna piana alluvionale, costituisce un terrazzo deposizionale i cui elementi morfologici principali (superficie sommitale e scarpata) sono stati fortemente rimodellati dagli agenti esogeni. in base alle caratteristiche granulometriche e tessiturali, al grado di arrotondamento dei clasti, alla presenza, in alcuni casi, di embricatura dei ciottoli, questi depositi possono essere ascritti a facies torrentizie. l’attribuzione di un’età a questi sedimenti appare problematica. infatti, anche se la loro posizione altimetrica è comparabile con quella dei depositi alluvionali affioranti nel settore meridionale della conca, attribuiti al pleistocene medio finale (cfr. par. 5.4.), l’assenza di minerali di natura piroclastica nella matrice induce ad ipotizzare una loro messa in posto precedente al vulcanismo monogenico di carsoli ed a quello dei grandi centri peri-tirrenici. 5.3. vulcaniti della conca di carsoli nella parte centro-occidentale e meridionale della conca intermontana di carsoli, inizia bruscamente, a partire da un’articolata superficie erosiva modellata nei depositi lacustri e nel substrato carbonatico mesocenozoico, una peculiare sequenza di terreni vulcanici. si tratta di prodotti piroclastici di genesi locale, connessi alla presenza in quest’area di un vulcanismo monogenico medio-pleistocenico (barbieri et alii, 1997, 2000; società geologica italiana, 2003; d’orefice & graciotti, 2005; d’orefice et alii, 2006). le vulcaniti sono state datate con il metodo 40ar/39ar a 0,531 ma da bosi et alii (1991) e con il metodo rb/sr a 0,540 ma da d’orefice et alii (2006). la maggior parte dei prodotti vulcanici, e presumibilmente dei centri d’emissione, è localizzato nel settore centro-occidentale della conca, poco a nord di oricola, e nel settore meridionale, tra colle s. vito e camerata nuova e lungo il fosso rientro. un edificio isolato si trova nei pressi di col farolo, tra oricola e carsoli (fig. 2). gli affioramenti ubicati in sinistra del fosso fioio, tra gli abitati di rocca di botte e camerata nuova, si allineano con direzione nno-sse in corrispondenza della probabile prosecuzione, al di sotto della coltre continentale, della faglia normale d’interesse regionale del fosso fioio, a cui alcuni autori (devoto, 1967a; damiani, 1990; naso et alii, 1991; compagnoni et alii 1993) attribuiscono un’evoluzione tettonica complessa. nelle sequenze vulcaniche, costituite in prevalenza da tufi subaerei, non sono stati trovati paleosuoli né superfici erosive generalizzate imputabili a lunghe stasi eruttive (barbieri et alii, 2000). l’inclinazione degli strati è in genere poco accentuata, mentre sono frequenti le laminazioni incrociate e le strutture dunari, anche a scala metrica, associabili a surge. le varie facies deposizionali si presentano spesso con rapporti laterali eteropici o canalizzati. sono state riscontrate anche evidenti discordanze angolari e piccole faglie con rigetto da pochi centimetri ad alcuni decimetri, evidenti negli affioramenti di collina rostere e di oricola scalo (d’orefice & graciotti, 2005). la stratigrafia di dettaglio, ricostruita sulla base dei vari affioramenti presenti nel bosco di oricola e nell’area limitrofa all’autostrada roma-l’aquila a24, ha 63 fig. 5 ghiaie della madonna delle grazie (flg) affioranti nei pressi della località cerretine: ghiaie da centimetriche a decimetriche e blocchi a cui s’intercalano piccole lenti sabbiose. la porzione granulometricamente più fine del deposito è caratterizzata dall’assenza di minerali femici di natura piroclastica. madonna delle grazie gravels (flg) outcropping near cerretine: centimetric to decimetric gravels and blocks with intercalated sandy lenses. the finer components are characterized by the absence of mafic pyroclactic elements. evoluzione geomorfologica quaternaria ... permesso di riconoscere tre principali unità piroclastiche, che corrispondono ad altrettante fasi eruttive. quindi, all’interno di questa formazione sono stati distinti i seguenti membri, elencati dal basso verso l’alto (fig. 3 e 6): 1) brecce d’apertura di oricola scalo (bao); 2) tufi grigi di oricola scalo (tgo); 3) tufi rossi di s. giovanni (trg). dalle analisi chimiche, mineralogiche e petrografiche, concentrate sul membro dei tufi grigi di oricola scalo (tgo), poiché meno alterato degli altri, è emerso che la frazione juvenile di questi tufi è composta da lapilli non vescicolari plasticamente deformati e saldati tra loro, da lapilli altamente vescicolari (pomici), da frammenti vetrosi e da frammenti cristallini di leucite, flogopite, diopside e k-feldspato, spesso immersi in una matrice micritica (<1µm) e compatta di calcite. tra i minerali accessori sono presenti lo spinello magnetitico, l’apatite, il granato e l’olivina. la calcite micritica estratta dai lapilli è chimicamente molto diversa da quelle delle rocce sedimentarie e la sua composizione isotopica fornisce valori simili a quelli delle altre fasi mineralogiche e della roccia totale. inoltre, questi valori differiscono in modo significativo da quelli ottenuti sui carbonati sedimentari dell’area di oricola e sui clasti carbonatici incorporati nelle brecce d’apertura di oricola scalo (bao). in base alla composizione mineralogica ed alla moda generale, questi litotipi possono essere classificati come fono-foiditi e foiditi. quando il contenuto della matrice carbonatica di origine ignea è superiore o prossimo al 50% del volume totale della roccia, tali litotipi possono considerarsi carbonatitici o carbonatiti s.s. per una descrizione dettagliata delle caratteristiche minero-petrografiche e geochimiche delle unità piroclastiche individuate si rimanda, comunque, ai lavori specifici di barbieri et alii (2000), d’orefice & graciotti (2005) e d’orefice et alii (2006). di queste tre unità principali affiorano ampiamente solo le ultime due, mentre la prima, essendo legata alle fasi precoci d’apertura del condotto, affiora raramente. essa è stata incontrata soprattutto in alcuni sondaggi a carotaggio continuo appositamente eseguiti nell’area (servizio geologico nazionale, 2000); alcune osservazioni sono, tuttavia, possibili in blocchi, non in sito, provenienti da un vicino sbancamento effettuato nei pressi della stazione ferroviaria di oricola-pereto. le sequenze vulcaniche sopra citate a volte terminano con epiclastiti, costituite da lenti di sabbie ricche in cristalli, originate dal rimaneggiamento esogeno dei depositi primari. 5.3.1. brecce d’apertura di oricola scalo (bao) le brecce d’apertura di oricola scalo sono costituite da strati di spessore pluridecimetrico a struttura massiva che comprendono clasti calcarei d’origine sedimentaria, a spigoli vivi e di dimensioni centimetriche, immersi in una matrice cineritica grossolana (fig. 7). all’interno della matrice, inoltre, si rinvengono piccoli lapilli mediamente vescicolati, tra cui spiccano cristalli centimetrici di mica. tra i cristalli sono presenti anche pirosseno, leucite, k-feldspato e magnetite. gli strati sono a volte separati da intercalazioni di tufo a laminazione incrociata, riferibile a strutture tipo ripples, forse da ricondurre a fenomeni di base surge. questo membro risulta coerente per l’esistenza di cementi carbonatici. una parte dei clasti carbonatici d’origine sedimentaria è costituita da litotipi non affioranti nelle immediate vicinanze della conca di carsoli, ma che verosimilmente, provengono dal basamento attraversato dal condotto eruttivo, dato che i clasti carbonatici presenti nei depositi continentali circostanti, ed in posizione interna alla conca, non hanno caratteristiche compatibili con quelle delle brecce suddette. all’interno di quest’unità sono, inoltre, presenti vuoti, eventualmente riempiti da cementi secondari, lasciati da macrofossili vegetali e porzioni di fusti riferibili a graminacee (giardini m., comunicazione personale) completamente sostituiti da calcite. i macroresti vegetali mostrano che il materiale è stato inglobato violente64 fig. 6 colonna stratigrafica ricostruita sulla base dei vari affioramenti individuati nel bosco di oricola. si tratta di una complessa sequenza di prodotti da flusso piroclastico, surge e caduta (airfall) (parzialmente modificata da barbieri et alii, 2000). stratigraphic section of the various volcanic outcrops identified in the bosco di oricola, showing a complex sequence of pyroclastic flow, surge and airfall products (partially modified after barbieri et alii, 2000). m. d’orefice et al. mente, frammentato ed isorientato durante la messa in posto di questa prima unità eruttiva. gli strati di breccia sono stati interpretati per lo più come depositi molto prossimali da caduta (airfall) e/o da debris flow, relativi alla fase di apertura del condotto (barbieri et alii, 2000; d’orefice et alii, 2006). 5.3.2. tufi grigi di oricola scalo (tgo) i tufi grigi di oricola scalo sono costituiti da un insieme di facies variabili da straterelli di cinerite a laminazione pianoparallela o incrociata fino a strati massivi di cinerite (barbieri et alii, 2000) (fig. 8). questi ultimi sono saldati e molto competenti con accenni di jointing da contrazione ed evidente frattura concoide. lo spessore di questo membro, affiorante estesamente nel bosco di oricola, è mediamente intorno ai 2 metri, ma può raggiungere i 10 m circa presso l’area di servizio della a24 “civita nord”. l’affioramento più significativo è quello corrispondente alla colata piroclastica che si allunga in direzione e-o tra la collina rostere (quota 630 m s.l.m.) e la s. s. tiburtina valeria (quota 605 m s.l.m.), secondo una stretta fascia di circa 1,9 km di lunghezza (fig. 2). dalle evidenze di campagna e soprattutto dai sondaggi geognostici realizzati trasversalmente all’asse della colata (fig. 9), essa corrisponde ad un corpo canalizzato all’interno di una preesistente vallecola incisa nei depositi lacustri (lao). in conseguenza dell’inversione del rilievo ad opera dell’erosione selettiva, la colata piroclastica si trova attualmente lungo un displuvio, dove origina uno stretto ripiano tabulare. all’interno di questo membro sono stati individuati calchi di frammenti di legno, rami e foglie aghiformi di conifere, attribuibili prevalentemente a gimnosperme della famiglia delle pinaceae (generi abies, pinus e picea) (giardini & follieri, 1992) ed in subordine ad angiosperme (generi alnus, carya e zelkova) (giardini & sadori, in sadori, 2005). alcuni taxa come alnus, ma soprattutto abies e carya, richiedono condizioni clima65 fig. 7 brecce d’apertura di oricola scalo (bao): clasti calcarei spigolosi di natura sedimentaria, immersi in una matrice cineritica grossolana, da cui spiccano cristalli centimetrici di mica. nella matrice sono, inoltre, presenti frammenti di fusti vegetali completamente sostituiti da calcite. the oricola scalo opening-vent breccias (bao): sharp edged limestone sedimentary clasts immersed in a coarse cineritic matrix including centimetric crystals of mica and vegetal fragments completely substituted by calcite. fig. 8 tufi grigi di oricola scalo (tgo) affioranti all’interno del bosco di oricola. i tufi sono stratigraficamente sovrapposti ai depositi lacustri (lao) attraverso una superficie di erosione. the oricola scalo grey tuffs (tgo) outcropping at bosco di oricola. the tuffs stratigraphically overlay the lacustrine deposits (lao) by means of an erosion surface. fig. 9 sezione geologica a-a’, ricostruita per mezzo dei sondaggi meccanici effettuati nei pressi di oricola scalo in direzione trasversale all’asse della colata. geological section a-a' near oricola scalo. the section has been reconstructed by coreholes drilled transversely to the pyroclastic flow axis. evoluzione geomorfologica quaternaria ... tiche di tipo spiccatamente oceanico, caratterizzate cioè da una considerevole umidità atmosferica. i dati paleobotanici acquisiti sono perfettamente compatibili con le età attribuite a questi prodotti da bosi et alii (1991) e d’orefice et alii (2006). barbieri et alii (2000) e d’orefice et alii (2006) attribuiscono a questi depositi vulcanici una messa in posto, connessa, in prevalenza, a meccanismi di pyroclastic flow e di surge. 5.3.2. tufi rossi di s. giovanni (trg) i tufi rossi di s. giovanni sono costituiti da una fitta alternanza di strati cineritici grossolani e fini, con lapilli pomicei generalmente rotti e brecciati e localmente con gusci cineritici accrezionari. essi sono essenzialmente sovrapposti sia ai sottostanti tufi grigi (tgo), sia ai depositi lacustri precedentemente descritti (lao) (fig. 3). i tufi rossi hanno uno spessore (fino a 15 m) ed un’estensione areale di gran lunga maggiore di quella delle unità eruttive sottostanti. la giacitura varia da orizzontale ad inclinata (da 5° a 20°), rispecchiando la morfologia del substrato. in questa unità si notano appoggi in netta discordanza angolare, canali sindeposizionali, forme ammantanti e strutture dunari anche di dimensioni metriche (fig. 10) (barbieri et alii, 2000). i tufi non si presentano compatti ed inoltre sono frequentemente interessati da orizzonti con patine limonitiche e da un’intensa pedogenizzazione negli strati superiori. in base alle strutture sedimentarie e alle caratteristiche strutturali, questa unità è stata interpretata da barbieri et alii, 2000 come un’alternanza di depositi da surge e da caduta (airfall). la porzione superiore delle collinette che caratterizzano la zona compresa tra il bosco di oricola ed i contrafforti carbonatici meridionali è in gran parte costituita da questi materiali, i quali danno luogo a collinette, rimodellate dagli agenti esogeni, dalla forma conica, ellittica o semicircolare (fig. 2). 5.4. ghiaie, sabbie e limi dei prati (flp) a nord e ad est della piccola struttura carbonatica di colle s. vito, affiora un esteso corpo sedimentario rilevato di circa 15 – 20 m sulla piana alluvionale sottostante. la maggior parte del litosoma è compresa tra il fosso fioio-secco ed il fosso s. mauro (fig. 2). il limite inferiore di questo corpo sedimentario terrazzato è rappresentato da una superficie d’erosione fluviale irregolare, che lo pone a diretto contatto sia con il substrato carbonatico (nell’estremo settore meridionale della conca) e sia con i depositi lacustri e vulcanici (nel settore centro-meridionale della medesima depressione) (fig. 3). la mancanza di sezioni naturali e artificiali significative e di dati geognostici non ha consentito di delineare l’architettura interna di questa unità deposizionale. tuttavia, sulla base dei dati di campagna relativi alla distribuzione ed alla granulometria dei depositi affioranti in superficie, è possibile distinguere zone con prevalenza di sedimenti grossolani, alternate a zone essenzialmente caratterizzate da sedimenti fini. le prime sono contraddistinte principalmente da ghiaie grossolane e blocchi (diametro massimo intorno ai 30 cm) con tessitura a supporto di clasti e matrice sabbioso-limosa ricca in minerali vulcanici; i singoli elementi presentano un elevato indice di arrotondamento e sono costituiti da litotipi carbonatici di piattaforma (fig. 11). le seconde, più frequenti alla sommità del corpo sedimentario, sono invece rappresentate da limi sabbioso-argillosi e argille limose con abbondanti minerali di origine vulcanica. il corpo sedimentario presenta marcate variabilità di spessore, passando, in breve distanza, da spessori nulli a spessori intorno ai 20 m. il litosoma è delimitato superiormente da un’estesa superficie, corrispondente con il piano topografico, che si sviluppa più o meno tra le quote 700 e 620 m circa; tale superficie, coincidente con l’originaria superficie deposizionale, mostra un’inclinazione di circa un grado verso no. i depositi in questione sono alterati al tetto da 66 fig. 10 tufi rossi di s. giovanni (trg) affioranti tra l’a24 e la stazione ferroviaria di oricola-pereto, in corrispondenza di uno sbancamento antropico. i tufi sono caratterizzati da una fitta alternanza di cineriti grossolane e fini e da strutture dunari. the s. giovanni red tuffs (trg) outcropping between the a24 highway and the oricola-pereto railway station, next to a manmade cut. they are characterized by a tight alternance of coarse and fine cinerites showing dune structures. fig. 11 località “prati”: ghiaie eterometriche appartenenti alla facies grossolana dell’unità dei prati (flp). le ghiaie, ben arrotondate, sono costituite da litotipi carbonatici di piattaforma, mentre la matrice sabbioso-limosa è ricca di minerali vulcanici. le ghiaie sono sovrapposte all’unità dei tufi rossi di s. giovanni (trg). prati: heterometric gravels belonging to the coarse facies of the prati unit (flp). the well-rounded gravels consist of carbonate platform lithotypes, whereas the sandy-silty matrix is rich in volcanic minerals. the gravels rest on the s. giovanni red tuffs unit (trg). m. d’orefice et al. mollisuoli e alfisuoli sui depositi ghiaiosi e da entisuoli sui sedimenti più fini (colica et alii, 1995). il corpo sedimentario è dissecato dai diversi corsi d’acqua di provenienza simbruina, che si immettono nel settore meridionale della conca di carsoli. lembi isolati di modeste dimensioni, appartenenti a questa formazione, si rinvengono anche alla base del versante meridionale di col farolo, tra quota 610 e 625 m s.l.m., nei pressi della stazione di servizio della a24 (civita nord), tra quota 610 e 630 m s.l.m., e nei dintorni della collina rostere, intorno alla quota 615 m. in considerazione degli aspetti geometrici, tessiturali, e morfologici è possibile interpretare il corpo sedimentario in questione come la porzione più distale di un antico conoide di deiezione, che progressivamente sfumava, verso no, ad un ambiente di piana alluvionale. la deposizione del litosoma posteriormente ai prodotti del vulcanismo monogenico di carsoli, la posizione altimetrica della superficie sommitale relitta, il suo grado di evoluzione nei riguardi dei processi erosivi, nonché le caratteristiche pedogenetiche dei suoli su di essa sviluppatisi, fanno propendere per un’età del corpo sedimentario riferibile alla parte finale del pleistocene medio. 5.5. tufi calcarei di fonte bosco (cfb) i tufi calcarei di fonte bosco affiorano circa un chilometro a nord di colle s. vito, intorno alla quota di 635 m. essi costituiscono un corpo, leggermente inclinato verso oso, i cui resti danno luogo ad una forma planimetrica pressappoco triangolare, estesa in lunghezza per circa 250 m e larga al massimo circa 100 m (fig. 2). il corpo sedimentario, di spessore variabile tra 0,5 e 1,5 m circa, inferiormente poggia su una superficie erosiva modellata a spese sia dei depositi lacustri del bosco di oricola (lao) e sia della litofacies più grossolana delle ghiaie, sabbie e limi dei prati (flp), ad essi soprastante (fig. 3). il litosoma è delimitato superiormente da un suolo scuro evoluto da terreni ricchi in materiali vulcanici rimaneggiati, su cui si è sviluppato un rigoglioso castagneto (dramis et alii, 2008) (fig. 12). di un certo interesse è la presenza, nei dintorni del corpo sedimentario in esame, di concrezioni carbonatiche diagenetiche e di frammenti di vulcaniti grigie litoidi. il deposito carbonatico (65% di caco3) nel complesso si presenta grossolanamente stratificato in livelli coerenti. ad un’osservazione macroscopica il litotipo appare compatto, di colore marrone-giallognolo (10yr 6/4) e formato da fanghi di natura calcarea. internamente sono visibili ad occhio nudo alcuni gasteropodi polmonati di acque basse (lymnaea truncatula) e terrestri (genere euconulus) (esu d., comunicazione personale). tra le strutture post deposizionali, frequenti sono le mineralizzazioni di manganese, anche in forma dendritica, i cristalli e le vene di calcite orientate in modo casuale e le patine di color marrone scuro, anch’esse prive di un’orientazione prevalente. l’esame al microscopio polarizzatore di alcune sezioni sottili e le analisi diffrattometriche, hanno consentito d’individuare la seguente composizione mineralogica: 1) calcite micritica in percentuale predominante; 2) quarzo di apporto terrigeno, fillosilicati e mica (paragonite) in tracce. in base al contenuto mineralogico rilevato, il litotipo può essere classificato come calcare micritico. secondo dramis et alii (2008), il deposito carbonatico potrebbe essere classificato come freshwater travertine o calcareous tufa (pedley, 1990). una datazione isotopica, realizzata con il metodo dei disequilibri nella serie dell’uranio, eseguita sul deposito carbonatico, ha fornito una età di 46 ± 6 ka bp (dramis et alii, 2008). nella datazione si è tenuto in debito conto della presenza d’impurità applicando un metodo di correzione (total sample dissolution), che consiste nell’analizzare differenti sub-campioni dello stesso affioramento. questa datazione colloca il deposito carbonatico all’interno dello stadio isotopico mis 3, definito anche interstadio pleniglaciale (follieri et alii, 1989), essendo una fase di relativo riscaldamento tra il mis 4 (i pleniglaciale) e il mis 2 (ii pleniglaciale). il rapporto d’incassamento del deposito carbonatico con le ghiaie, sabbie e limi dei prati (flp), conferma, per quest’ultima formazione, un’età molto più antica dello stadio isotopico 3. 5.6. conglomerati del fosso fioio (cof) nel tratto di fondovalle che va dallo sbocco del fosso fioio nella conca di carsoli (poco prima di camerata nuova) alla località il casale (comune di rocca di botte), affiora una stretta fascia di depositi conglomeratici (fig. 2) che termina, in parte sotto forma di ghiaie sciolte, poco prima di colle s. vito. complessivamente il deposito è clasto-sostenuto; la matrice è solitamente assente, nei rari casi in cui è presente essa è costituita prevalentemente da sabbie ricche in minerali femici di natura vulcanica (fig. 13). i clasti, di origine carbonatica, litologicamente appartengono alla serie locale di piattaforma interna lazialeabruzzese. essi sono eterometrici (alcuni raggiungono il metro di diametro), di forma generalmente sferica e con grado di arrotondamento variabile da subangoloso a subarrotondato (litofacies gm di miall, 1977, 1978, 1985). nell’insieme il sedimento si presenta mal classato, non si osservano embricature nei clasti e canali d’erosione. 67 fig. 12 piccolo rilievo, ubicato circa 1 km a nord di colle s. vito, la cui parte sommitale è formata dai tufi calcarei di fonte bosco (cfb). questo deposito è ricoperto da un suolo scuro ricco di minerali vulcanici, sul quale si è sviluppato un boschetto di castagni. a small hill located ca. 1 km north of colle s. vito topped by the fonte bosco calcareous tufa (cfb). this deposit is covered by a brown soil rich in volcanic elements over which a small chestnut grove has grown. evoluzione geomorfologica quaternaria ... all’interno del deposito non si notano particolari strutture sedimentarie, tuttavia nel tratto compreso tra camerata nuova e rocca di botte si evidenzia una stratificazione grossolana pressoché orizzontale, sottolineata da un’alternanza di livelli formati da clasti a differente grado di arrotondamento. il cemento è calcitico e in alcuni casi riempie tutti i vuoti intergranulari. un tentativo di datare il cemento con il metodo u/th non ha dato buon esito, poiché l’elevata componente detritica in esso contenuta, non ha consentito di ottenere dei complessi isotopici puri da analizzare allo spettrometro. i rapporti stratigrafici di quest’unità con le ghiaie, sabbie e limi dei prati (flp) non sono osservabili per la mancanza di affioramenti significativi. sulla base delle sole caratteristiche geometriche e morfologiche, quali la posizione allo sbocco della valle, la forma leggermente svasata nella parte terminale e le quote delle superfici relitte sommitali (coincidenti con l’originaria superficie deposizionale) lievemente decrescenti verso il centro della conca, è possibile interpretare il corpo sedimentario in esame come parte di un ben 68 fig. 13 conglomerati del fosso fioio (cof) affioranti nei pressi di fontanile brecciaro: conglomerati costituiti da clasti carbonatici eterometrici da subangolosi a subarrondati. la matrice è scarsa o assente, mentre il grado di cementazione varia da basso a medio. fioio stream conglomerates (cof) outcropping near fontanile brecciaro: conglomerates made of heterometric, sub-angular to sub-rounded, carbonatic clasts, with scarce or absent matrix and low to medium cementation level. fig. 14 ghiaie, sabbie e limi dell’immagine (fli), messi in luce dall’erosione laterale del fosso cammarano, nei pressi del centro commerciale “carsoli 2”: ghiaie grossolane eterometriche di riempimento di canale fluviale, sormontate, con contatto netto, da sedimenti più fini di tracimazione fluviale. immagine gravels, sands and silts (fli), exposed by the lateral erosion of fosso cammarano near the carsoli 2 commercial center: heterometric coarse channel-fill gravels, overlain with sharp contact by finer overbank sediments. più esteso conoide alluvionale. probabilmente la messa in posto di tale conoide può essere avvenuta nel pleistocene superiore, in concomitanza dell’ultima glaciazione. 5.7. ghiaie, sabbie e limi dell’immagine (fli) le aree pianeggianti della conca di carsoli, altimetricamente disposte pressappoco tra le quote di 690 m (estremo settore meridionale della conca) e 585 m s.l.m. (estremo settore settentrionale), sono occupate da depositi di piana alluvionale non più attivi e sospesi da alcuni metri fino a circa 10 m sull’attuale fondovalle del fiume turano e del fosso cammarano (fig. 2). i depositi in questione sono costituiti da ghiaie grossolane eterometriche (prevalentemente centimetriche), da sub-arrotondate ad arrotondate, generalmente in matrice sabbiosa, passanti lateralmente e verticalmente, con contatto netto, a sabbie limose e limi argilloso-sabbiosi scuri (fig. 14). minerali femici di origine vulcanica si rinvengono sia nella matrice delle ghiaie, sia nella frazione sabbiosa dei sedimenti fini. si sottolinea che i clasti facenti parte delle facies più grossolane hanno un grado di arrotondamento ed una dimensione massima (intorno ai 20-25 cm) inferiore a quella dei clasti appartenenti ai depositi fluviali più antichi della conca di carsoli (flg e flp). i depositi ghiaiosi danno luogo a corpi sedimentari a geometria prevalentemente nastriforme, larghi alcune centinaia di metri e spessi anche qualche decina di metri. essi incidono, con contatto netto ed erosivo, i depositi più fini adiacenti, dando origine a canali di piana alluvionale. il limite inferiore è costituito da una superficie erosiva, che pone questo corpo sedimentario a diretto contatto sia con il substrato carbonatico (settore meridionale della depressione) e sia con le più antiche unità stratigrafiche continentali (lao, flg, tgo, trg, flp e cof). il limite superiore è rappresentato da una vasta superficie d’accumulo sub-orizzontale, coincidente con m. d’orefice et al. il piano topografico su cui corre la viabilità principale della conca (s.s. 5 tiburtina valeria, s.p. 27 del cavaliere, s.p. 48/b camerata nuova, via spineta). in superficie questi depositi sono caratterizzati da suoli abbastanza evoluti, che vanno da entisuoli a mollisuoli sui depositi più grossolani e da entisuoli ad alfisuoli sui sedimenti più fini (colica et alii, 1995). su alcuni livelli organici presenti all’interno di quest’unità stratigrafica sono state effettuate due datazioni al radiocarbonio, le quali hanno fornito le seguenti età calibrate: i) 4.180 – 3.940 anni cal bc (campione cedad-ltl3919a, prelevato alla sommità della formazione, lungo la sponda destra del fosso fioio, presso fontanile brecciaro – fig. 15); ii) 12.450 – 11.900 anni cal bc (campione cedad-ltl3920a, prelevato alla base della sponda sinistra del fosso fioio, presso fontanile brecciaro fig. 16). la gran parte dei conoidi inattivi ubicati in corrispondenza dello sbocco nella conca delle principali valli fluviali possono essere correlati a questi depositi, in quanto fisicamente in continuità morfologica con essi. in base alle considerazioni sopra esposte, e soprattutto alle datazioni radiometriche, si può ipotizzare per i depositi alluvionali, come anche per i conoidi inattivi, un periodo di formazione compreso tra il tardoglaciale e l’olocene antico. 5.8. ghiaie, sabbie e limi del fiume turano (flt) i sedimenti appartenenti a questa unità si rinvengono lungo i fondovalle attuali della conca e corrono incassati principalmente all’interno della formazione delle ghiaie, sabbie e limi dell’immagine (fli), terrazzandola, a sud-ovest di col farolo, a sud del convento di s. francesco e in località macerone, in almeno due ordini. si tratta di sedimenti prevalentemente limososabbiosi, affioranti lungo i fondovalle percorsi dal fosso carcarone, compreso il reticolo ad esso affluente, e dal fosso rientro. alternanze di strati ghiaiosi con strati limoso-sabbiosi e sabbioso-limosi si rinvengono, invece, lungo gli alvei dei fossi fioio, secco, s. mauro, pachetto e cammarano. tali alternanze sono ben evidenti anche lungo le sponde del fiume turano (fig. 17) e nelle aree ad esso adiacenti; tuttavia, a breve distanza dall’asse fluviale, affiorano in superficie depositi granulometricamente più fini, come ad esempio in destra del fosso carcarone (località pezze della mola), dove si 69 fig. 15 parte superiore dell’unità delle ghiaie, sabbie e limi dell’immagine (fli), affiorante lungo la sponda destra del fosso fioio, presso fontanile brecciaro. in evidenza sedimenti fini ricchi in materia organica, intercalati nei depositi ghiaiosi. la datazione al radiocarbonio di un campione prelevato in tale livello ha fornito l’età calibrata di 4.180 – 3.940 anni bc. upper part of the immagine gravels, sands and silts (fli), outcropping along the right bank of the fioio stream, near fontanile brecciaro. note the fine sediments, rich in organic matter, that are interbedded in the gravelly deposits. radiocarbon dating of a sample taken from this level provided a calibrated age of 4,180 to 3,940 years bc. fig. 16 parte inferiore dell’unità delle ghiaie, sabbie e limi dell’immagine (fli), affiorante lungo la sponda sinistra del fosso fioio, presso fontanile brecciaro. si notano sedimenti fini ricchi in materia organica, intercalati nei depositi ghiaiosi. la datazione al radiocarbonio di un campione prelevato in tale livello ha fornito l’età calibrata di 12.450 – 11.900 anni bc. lower portion of the immagine gravels, sands and silts (fli), outcropping along the left bank of the fioio stream, at fontanile brecciaro. note the fine sediments, rich in organic matter, that are interbedded in the gravelly deposits. radiocarbon dating of a sample taken from this level provided a calibrated age of 12,450 to 11,900 years bc. fig. 17 ghiaie, sabbie e limi (flt) affioranti lungo la sponda destra del fiume turano: ghiaie grossolane di riempimento di canale fluviale passanti superiormente, con contatto netto ed erosivo, a limi sabbiosi di tracimazione, finemente stratificati e ricchi di sostanza organica. gravels, sands and silts (flt) outcropping on the right side of the turano river: coarse channel-fill gravels passing upwards, with a sharp erosional contact, to finely stratified, overbank sandy silt sediments, rich in organic matter. evoluzione geomorfologica quaternaria ... passa ad una piana alluvionale costituita da limi argillosi e argille limose di tracimazione fluviale. in questa piana la continuità laterale dei depositi fini è a volte interrotta da sottili fasce (non cartografabili) di sedimenti più grossolani (in genere sabbie e ghiaie) dall’andamento in pianta arcuato, riconducibili a meandri abbandonati del f. turano. sempre in corrispondenza dell’attuale piana alluvionale del f. turano (località prata grande), le indagini geoelettriche hanno messo in evidenza l’esistenza di un paleocanale, a direzione circa est-ovest, leggermente spostato più a sud-ovest rispetto al corso d’acqua odierno. nella parte centrale dell’alveo del f. turano si possono osservare, in più punti, barre longitudinali in formazione costituite da ghiaie, passanti sottocorrente a sabbie grossolane. i suoli che a volte si osservano alla sommità di questa formazione sono caratterizzati da uno scarso grado di evoluzione pedogenetica (entisuoli, secondo colica et alii, 1995). una datazione al radiocarbonio effettuata su un legno carbonizzato rinvenuto all’interno di sedimenti limosi appartenenti a questa formazione (fig. 18) ha fornito un’età calibrata di 330 – 200 anni cal bc (cedadltl3921a), corrispondente al iv–ii sec. a.c. (età repubblicana di roma antica). il campione è stato prelevato alla base della sponda destra del f. turano, nei pressi della località macerone. ai depositi fluviali in esame si possono correlare alcuni conoidi di modeste dimensioni. tra questi possono essere citati quello di seconda generazione ad ovest di camerata nuova e quello del fosso luisa, ad est di camerata nuova. il rinvenimento di depositi databili all’interno di quest’ultimo conoide da parte di barbieri et alii (1998), è sicuramente d’indubbio significato, anche in considerazione del fatto che nell’area in esame sono quasi del tutto assenti i riferimenti cronologici relativi ai depositi quaternari continentali. il conoide del fosso luisa è ubicato 300 m ad est di camerata nuova (m.ti simbruini nord-orientali), in corrispondenza del tratto terminale dell’angusta valle a “v” percorsa dal fosso omonimo, affluente di sinistra del fosso fioio (fig. 2). in pianta il conoide ha una forma stretta ed allungata, con circa 200 m di larghezza massima e 1.200 m di lunghezza; la sua pendenza media si aggira intorno al 10% e lo spessore è superiore ai 5 m. in un taglio antropico è stato possibile individuare una successione che mostra le caratteristiche stratigrafiche e sedimentologiche della parte superiore del conoide. tale successione è costituita da (fig. 19): 1) uno strato inferiore di ghiaie calcaree eterometriche a spigoli smussati, con tessitura a supporto di matrice e gradazione inversa; 2) uno strato intermedio formato da sedimenti argilloso-limosi debolmente sabbiosi di colore 5yr3/4 (bruno rossastro scuro), contenenti piccoli frammenti di ceramica fluitata e con tracce di pedogenesi; 3) uno strato superiore di ghiaie e blocchi calcarei eterometrici, a spigoli smussati, con tessitura a supporto di clasti e gradazione inversa. la datazione con il metodo del 14c delle sostanze organiche presenti nello strato intermedio, interpretato come un deposito d’origine colluviale (barbieri et alii, 1998), ha fornito un’età radiometrica convenzionale di 3.270 ± 50 anni bp e un’età calibrata variabile tra 3.550 3.400 anni bp. in generale le carat70 fig. 18 depositi fluviali (flt) affioranti lungo la sponda destra del fiume turano: strato limoso contenente del materiale ligneo carbonizzato. la datazione al radiocarbonio di tale reperto ha fornito l’età calibrata di 330 – 200 anni bc. fluvial deposits (flt) outcropping on the right bank of the turano river: silty layer containing carbonised wood. radiocarbon dating provided a calibrated age of 330 to 200 years bc. fig. 19 sezione schematica stratigrafica della parte superiore del corpo del conoide del fosso luisa (camerata nuova) (parzialmente modificata da barbieri et alii, 1998). legenda: 1) strato inferiore di ghiaie calcaree eterometriche con tessitura a supporto di matrice e gradazione inversa; 2) deposito colluviale a granulometria fine; 3) strato superiore di ghiaie e blocchi calcarei eterometrici, con tessitura a supporto di clasti e gradazione inversa. schematic stratigraphic section of the upper part of the luisa stream alluvial fan (camerata nuova) (partially modified after barbieri et alii, 1998). legend: 1) lower layer of heterometric calcareous gravels with matrix-supported texture and reverse grading; 2) fine-grained colluvial deposit; 3) upper layer of heterometric calcareous gravels and blocks, with clast-supported texture and reverse grading. m. d’orefice et al. teristiche sedimentologiche di entrambi gli strati ghiaiosi (basso grado di selezionamento, assenza di embricatura, gradazione inversa e la presenza di grossi massi alla sommità dell’affioramento) consentono d’ipotizzare un meccanismo di sedimentazione di tipo debris flow. 5.9. colluvi e detriti di versante (cdv) i depositi di natura colluviale si rinvengono al piede di aree interessate da processi di dilavamento, nel luogo in cui le condizioni morfometriche del versante consentono la loro deposizione. generalmente si tratta di sedimenti fini limoso-argillosi di spessore modesto (fino a circa 3 m), a struttura massiva, contenenti frequentemente ciottoli sparsi e frammenti di laterizi, che consentono di riferire la loro formazione almeno in parte all’olocene. questi depositi, distribuiti prevalentemente alla base dei rilievi, sono diffusi nelle aree di affioramento dei litotipi terrigeni e lacustri, ma si riscontrano anche in corrispondenza dei versanti carbonatici. i detriti di versante si rinvengono addossati ai piedi dei rilievi calcarei e calcareo-marnosi che bordano la conca di carsoli, dove danno luogo a fasce strette ed allungate. in particolare essi sono presenti alla base dei monti sabini orientali e ai piedi delle dorsali carbonatiche appartenenti ai m.ti simbruini nord-orientali, che racchiudono il settore meridionale della conca. i detriti di versante sono costituiti da clasti carbonatici sciolti, eterometrici, a spigoli vivi ed hanno una matrice terrosa. lo spessore massimo di questi depositi è dell’ordine di alcuni metri. 6. evoluzione geomorfologica dell’area i dati geologici, geomorfologici e geocronologici consentono di delineare, anche se in maniera incompleta e per certi versi incerta, una serie di eventi sedimentari ed erosivi che hanno caratterizzato quest’area. pertanto, viene qui di seguito riportata, in forma sintetica, la ricostruzione delle principali tappe evolutive che hanno interessato la conca in esame. dal messiniano al pliocene inferiore avviene il corrugamento generale della serie marina meso-cenozoica ad opera di fasi tettoniche compressive (cavinato et alii, 1986) e la sua definitiva emersione. a partire dal pliocene medio l’area viene interessata da una fase tettonica estensionale, caratterizzata da faglie dirette, che ribassano le strutture compressive (cavinato et alii, 1986). nel corso di questo periodo e sino al pliocene superiore avviene, secondo ambrosetti et alii (1987), un abbassamento dell’area, seguito da una risalita. nel pleistocene inferiore, in conseguenza di un nuovo abbassamento (ambrosetti et alii, 1987), verosimilmente si va progressivamente delineando una depressione, contraddistinta da un drenaggio centripeto, in cui inizialmente, con molta probabilità, si vanno a depositare, in analogia con altre conche intermontane, sedimenti di natura fluviale. si ritiene, infatti, che agli inizi del pleistocene il richiamo del drenaggio verso la conca di carsoli abbia consentito l’ingresso e la deposizione al suo interno di antichi sedimenti fluviali, prevalentemente grossolani, provenienti da nord e trasportati da un paleo-turano con verso di scorrimento opposto a quello attuale (chiarini et alii, 2009). questi depositi, non affioranti all’interno della conca, costituiscono un potente corpo alluvionale che improvvisamente termina in corrispondenza di turania. in seguito, lo stabilirsi di vere e proprie condizioni di endoreicità consentono la deposizione di una successione prevalentemente lacustre (limi, argille e sabbie del bosco di oricola – lao), costituita da alternanze di strati argilloso-limosi e sabbioso-limosi, il cui spessore è stato stimato intorno ai 200 m. verso la fine del pleistocene inferiore, in conseguenza del rapido e generalizzato sollevamento di tutto l’appennino centrale, si registra un forte incremento dell’erosione lineare, che produce un generale e veloce approfondimento delle incisioni vallive (dramis, 1992; d’agostino et alii, 2001). molto probabilmente, per effetto di questi eventi, come è avvenuto per altre depressioni tettoniche dell’appennino centrale (centamore et alii, 2006), la conca di carsoli viene raggiunta dall’erosione regressiva che, dopo avere aperto una soglia nel suo settore settentrionale, ha causato lo svuotamento del lago e la conseguente interruzione della sedimentazione lacustre. l’apertura di tale soglia porta allo sviluppo di una rete idrografica drenante verso nord ed alla deposizione, al di sopra dei depositi lacustri, di modesti spessori di sabbie fluviali, caratterizzate da strutture trattive che indicano una paleocorrente diretta verso i quadranti settentrionali. successivamente s’instaura un’intensa fase di erosione, che porta alla parziale asportazione dei depositi di chiusura del bacino lacustre. si origina, in questo modo, una vasta superficie di erosione blandamente inclinata verso i quadranti settentrionali. in seguito, lungo il margine settentrionale della conca di carsoli, s’imposta un corso d’acqua con direzione simile a quello dell’attuale f. turano, che dà luogo ai deposti grossolani in facies torrentizia, affioranti tra il convento di s. francesco e la località cerretine (ghiaie della madonna delle grazie – flg). movimenti differenziali, legati sempre a tettonica estensionale, probabilmente causano, lungo il margine orientale e nord-orientale della conca, il progressivo basculamento dei depositi lacustri, la loro fagliazione e l’individuazione di lembi sollevati a differenti quote. nel pleistocene medio (530-540.000 anni bp), dopo una fase erosiva di tipo lineare, nel settore centrooccidentale e meridionale della conca, ha inizio un’attività vulcanica monogenica, con una serie di centri di emissione allineati lungo la probabile prosecuzione, al di sotto della coltre continentale, della faglia normale d’importanza regionale del fosso fioio. l’attività, prevalentemente subaerea, ha dato origine prima a brecce eterogenee legate alle fasi precoci d’apertura del condotto (brecce d’apertura di oricola scalo – bao), poi a depositi da surge e da colata piroclastica (tufi grigi di oricola scalo tgo) ed infine a depositi da surge e caduta (tufi rossi di s. giovanni trg). l’assenza di paleosuoli o di estese superfici erosive post-deposizionali nelle sequenze vulcaniche individuate, sta a indicare che tra un evento deposizionale e l’altro non si sono verificate lunghe stasi eruttive. la presenza all’interno dei tufi grigi di oricola scalo di calchi di macroresti vegetali, attribuibili prevalentemente a gimnosperme della famiglia delle pinacee ed 71evoluzione geomorfologica quaternaria ... in subordine ad angiosperme, conferma un’attività vulcanica avvenuta principalmente in ambiente deposizionale subaereo. inoltre, alcuni taxa arborei (alnus, abies e carya) sono indicativi di condizioni di spiccata oceanicità (giardini & sadori, in sadori, 2005) e pertanto di un contesto paleoclimatico diverso da quello attuale. successivamente alla messa in posto delle vulcaniti ed al loro rimodellamento da parte del processo fluvio-denudazionale, nel pleistocene medio finale si assiste alla deposizione di sedimenti verosimilmente di transizione tra facies di conoide e di piana alluvionale (ghiaie, sabbie e limi dei prati flp) che, nel settore meridionale della conca, vanno a costituire un esteso corpo sedimentario di spessore massimo decametrico. alla fase di aggradazione fluviale segue, nel pleistocene superiore, una fase erosiva di tipo lineare che ha portato alla dissezione del corpo alluvionale in precedenza formatosi. nel corso dell’ultima glaciazione si ha la costituzione, sui rilievi più elevati dei m.ti simbruini, di estesi apparati glaciali. essi interessano anche la testata del fosso fioio che si trova molto più a sud dell’area in esame. l’abbondanza di apporti solidi, trasportati a valle dalle acque di fusione glaciale, determina la formazione del conoide fluviale del fosso fioio (conglomerati del fosso fioio – cof), costituito da conglomerati clasto-sostenuti prevalentemente massivi. durante un periodo di riscaldamento tra due pleniglaciali (stadi isotopici 4 e 2), e più precisamente intorno ai 46.000 ± 6.000 anni bp (datazione u/th – dramis et alii, 2008), è avvenuta la deposizione dei tufi calcarei di fonte bosco (cfb), affioranti un chilometro a nord di colle s. vito. questa datazione colloca, quindi, il deposito studiato all’interno dello stadio isotopico mis 3, definito anche interstadio pleniglaciale. nel corso di tale stadio le condizioni climatiche sono caratterizzate da un parziale aumento della temperatura e dell’umidità, come testimoniato dalle serie polliniche studiate in aree vicine, in particolare quelle della sequenza della valle di castiglione (follieri et alii, 1989), distante dalla conca circa 30 km. nel corso dell’interstadio pleniglaciale, nella sequenza di valle castiglione non si registra una vera e propria fase a foresta, ma la presenza di querce e faggi testimoniano l’esistenza di una piccola espansione del bosco. la datazione isotopica di questo deposito carbonatico conferma l’età più antica (pleistocene medio finale) delle ghiaie, sabbie e limi dei prati (flp) in cui esso è incassato. alla fine del tardoglaciale, una fase erosiva di tipo lineare interessa il conoide fluviale del fosso fioio e tutti i sedimenti in precedenza deposti. nel corso di tale fase avviene anche il modellamento dei tufi calcarei di fonte bosco (cfb). tra la fine del tardoglaciale e l’olocene antico, nell’area dell’immagine, si registra la messa in posto di sedimenti di piana alluvionale (ghiaie, sabbie e limi dell’immagine – fli), costituiti da depositi grossolani di canale, a geometria nastriforme, che tagliano, con contatto netto ed erosivo, i depositi più fini adiacenti. una successiva fase erosiva ha inciso tali depositi, i quali attualmente sono sospesi sul fondovalle del fiume turano e del fosso cammarano, attraverso almeno due ordini di terrazzo. nel tardo-olocene avviene la deposizione della porzione superiore del conoide del fosso luisa (a est di camerata nuova), il cui studio (barbieri et alii, 1998) ha consentito di delineare i seguenti eventi sedimentari: 1) deposizione, secondo meccanismi gravitativi di tipo debris flow, di uno strato inferiore di ghiaie calcaree, in un momento più antico di 3.550 3.400 anni cal bp; 2 messa in posto di depositi colluviali in un momento successivo a 3.550 3.400 anni cal bp; 3) deposizione, tramite meccanismi di tipo debris flow, di uno strato superiore di ghiaie e blocchi calcarei, in un momento molto più recente di 3.550 3.400 anni cal bp. i due episodi di sedimentazione grossolana potrebbero essere attribuiti alla diminuzione della copertura boschiva, imputabile ad una tendenza, in un contesto climatico olocenico per lo più temperato umido, verso periodi più secchi o caratterizzati da precipitazioni irregolari di forte intensità (frezzotti & giraudi, 1989; 1992). l’episodio molto più recente di 3.550 3.400 anni dal presente potrebbe anche essere attribuito al disboscamento connesso all’attività antropica. sempre nel tardo-olocene, nei fondovalle dei fossi ritorto, carcarone e rientro sedimentano terreni prevalentemente fini, mentre lungo gli alvei dei fossi fioio, secco, s. mauro, pachetto e cammarano e del fiume turano, avviene la deposizione di alternanze di strati sabbioso-limosi e limoso-sabbiosi con strati ghiaiosi (ghiaie, sabbie e limi del fiume turano – flt). attualmente si assiste ad una fase di incisione dei depositi fluviali recenti, con conseguente approfondimento del reticolo idrografico. questa fase erosiva ha messo a giorno i sedimenti lacustri (lao) lungo gli alvei dei fossi secco, di fonte bosco e cammarano e in corrispondenza di quello del f. turano. ringraziamenti gli autori ringraziano i due revisori anonimi per i preziosi suggerimenti forniti e i dottori mauro roma e valerio vitale per l’elaborazione grafica delle figure. bibliografia accordi g., carbone f., civitelli g., corda l., de rita d., esu d., funiciello r., kotsakis t., mariotti g. & sposato a. 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(1939) die eiszeitliche vergletscherung der zentralapennins. beiblatt zur vierteljahrsschrift, 84 (31), 140 pp. 74 ms. ricevuto il 23 novembre 2009 testo definitivo ricevuto il 19 aprile 2010 ms. received: november 23, 2009 final text received: april 19, 2010 m. d’orefice et al. imp.gioia_schiattarella caratteri morfotettonici dell’area del valico di prestieri e dei monti di lauria (appennino meridionale) dario gioia1 & marcello schiattarella1 1 dipartimento di scienze geologiche, università della basilicata, potenza riassunto: d. gioia & m. schiattarella, caratteri morfotettonici dell’area del valico di prestieri e dei monti di lauria (appennino meridionale). (it issn 0394-3356, 2006). i monti di lauria, ubicati ad occidente del bacino del mercure – che li separa dai vicini rilievi dalla catena del pollino rappresentano un alto strutturale di carbonati mesozoici la cui morfoevoluzione è stata fortemente controllata dalla tettonica quaternaria. a sud della dorsale compresa tra gli abitati di lauria e castelluccio si sviluppa per circa 15 km il “corridoio morfologico” del valico di prestieri, nel quale trovano posto sedimenti continentali quaternari organizzati in più corpi deposizionali. in questa nota viene proposto un quadro stratigrafico e morfostrutturale dell’intera area, unitamente alla ricostruzione della sequenza morfo-tettonoevolutiva neogenico-quaternaria. la primitiva struttura contrazionale neogenica risulta smembrata dalla riattivazione mediopleistocenica, in regime estensionale, di un’associazione di faglie originariamente prodotta durante il pliocene superiore – pleistocene inferiore in una zona di taglio orientata all’incirca n120°. sono stati riconosciuti diversi momenti di crisi tettonica nel pleistocene e periodi di quiescenza durante i quali ha avuto luogo il modellamento in corrispondenza del paleolivello di base locale dell’erosione di superfici erosionali più o meno estese e la genesi di corpi sedimentari con top deposizionali a bassa pendenza. l’utilizzo di simili indicatori morfotettonici – ai quali è stato possibile attribuire un’età per correlazione geomorfologica con i vicini bacini del mercure e del sinni ha permesso di valutare i tassi di sollevamento regionali e locali dell’area e la velocità di scivolamento delle principali faglie. i tassi del sollevamento regionale vanno ad assestarsi su valori di circa 1 mm/a mentre quelli locali sono corrispondenti in linea di massima ai tassi di attività delle faglie e raggiungono i valori più elevati (0,5-0,6 mm/a circa) al passaggio pleistocene inferiore–medio, in coincidenza dell’attivazione della tettonica estensionale ad asse ne-so. l’entità dell’esumazione quaternaria legata all’erosione lineare, calcolata attraverso il tasso di incisione delle superfici di spianamento relitte, risulta nettamente minore rispetto a quella necessaria per smantellare le volumetrie responsabili del carico tettonico ipotizzabile per l’area di studio. la necessità di invocare altri meccanismi di esumazione permette allora di collegare le faglie a basso angolo con cinematica normale o trastensiva, rilevate lungo i rilievi di monte la spina e monte zaccana, a fenomeni, probabilmente di età pliocenica, di denudamento tettonico dell’orogene. abstract: d. gioia & m. schiattarella, morphotectonics of the valico di prestieri area and adjacent lauria mts (southern appennines). (it issn 0394-3356, 2006). lauria-castelluccio mountains, located to the west of the mercure basin and separated by it from the pollino ridge, form a morphostructural high of the calabria-lucania border, southern italy, made of mesozoic shallow-water carbonates, whose evolution has been strongly controlled by quaternary tectonics. to the south of the ridge, a 15 km-long narrow depression, named valico di prestieri, is filled by continental pleistocene deposits organized in several sedimentary bodies. in this paper, the stratigraphic and morphostructural picture of the quaternary deposits and surrounding areas is widely discussed and, in the end, a reconstruction of miocene to pleistocene tectonic and morpho-evolutionary sequences is proposed. the original contractional structure – built on during late miocene to pliocene time-span – has been dismembered by pleistocene strike-slip and normal faulting along a n120°striking shear zone. several episodes of both tectonic crisis and quiescence have been recognized. during the quiescence periods, sculpture of erosional land surfaces and deposition of sedimentary bodies with gently dipping tops (alluvial fans and flood), both related to the different past base levels of the trough, took place. the use of such features as morphotectonic markers – whose ages have been deduced by morphostratigraphic correlations with the close mercure river and sinni river basins – allowed the estimation of the regional and local uplift rates and the calculation of the slip rates of the main high-angle faults. regional uplift rates are settled on a value of about 1 mm/yr, whereas the local rates are nearly coincident with the magnitude of the fault slip rates, reaching the highest values (about 0,5-0,6 mm/yr) at the passage between early and middle pleistocene, in correspondence of the beginning of the extensional tectonics with ne-sw oriented tensile axis. the amount of quaternary denudation due to fluvial erosion, calculated on the base of bedrock incision rates, is clearly less than tectonic burial (several km) suffered by the mesozoic formations of the lauria mts and surrounding areas. therefore, it is necessary to invoke alternative mechanisms of exhumation, such as tectonic erosion or denudation, that may adequately justify also the presence of lowangle normal or oblique faults, surveyed at mt. la spina and mt. zaccana and probably pliocene in age. parole chiave: evoluzione morfotettonica polifasica, tasso di sollevamento, faglia normale a basso angolo, denudamento tettonico, monti di lauria (appennino calabro-lucano). keywords: polyphase morphotectonic evolution, uplift rate, low-angle normal fault, tectonic denudation, lauria mts (calabria-lucania apennines, italy). il quaternario italian journal of quaternary sciences 19(1), 2006 129-142 1. introduzione i monti di lauria rappresentano una morfostruttura modellata nelle successioni calcareo-dolomitiche meso-cenozoiche di piattaforma costituenti le monoclinali del confine calabro-lucano (fig. 1), orlate a nord da un fronte di sovrascorrimento con vergenza verso n-ne e vistosamente smembrate dalla tettonica fragile plioquaternaria. la dorsale è infatti confinata a meridione dal corridoio morfotettonico del valico di prestieri, aggradato da sedimenti quaternari organizzati in più corpi deposizionali di ambiente continentale. in questa nota viene presentato uno studio geomorfologico della depressione e dei rilievi contigui, finalizzato alla rico130 d. gioia & m. schiattarella struzione della sequenza morfo-tettonoevolutiva che ha caratterizzato questo settore di catena dal neogene al quaternario. recenti studi enfatizzano il ruolo delle superfici di spianamento relitte e delle anomalie nei profili longitudinali dei corsi d’acqua come marker morfo-cronologici sui quali fondare le stime quantitative dei tassi di sollevamento regionali e locali della catena appenninica (schiattarella et al., 2003; 2006; boenzi et al., 2004). il buon grado di conservatività morfologica che caratterizza l’ossatura carbonatica dei monti di lauria e la presenza di diverse generazioni di depositi continentali nell’area del valico di prestieri, unitamente alla mancanza di studi a carattere morfostrutturale, sono i fattori che rendono di particolare interesse l’area di studio. il rilevamento geologico di dettaglio, con particolare riferimento ai depositi quaternari, ha interessato l’area compresa tra i rilievi di monte zaccana e monte la spina a nord e le dorsali di monte rossino e serra la nocara a sud. l’analisi geomorfologica è stata mirata in particolare alla dettagliata cartografazione delle superfici topografiche erosionali e/o deposizionali a basso angolo, oltre che al riconoscimento dei morfolineamenti di origine tettonica e di altri elementi del paesaggio fisico legati ai processi tettonici, ed è stata supportata anche dall’analisi morfometrica del reticolo idrografico, realizzata attraverso il calcolo di alcuni parametri geomorfici significativi dal punto di vista morfotettonico (rb, rbd, r) e la valutazione delle direzioni preferenziali di deflusso dei corsi d’acqua. l’analisi mesostrutturale degli elementi della deformazione fragile, con particolare riguardo allo stato di fratturazione dei terreni del bedrock carbonatico pre-quaternario, si è resa necessaria per la comparazione degli andamenti delle aste fluviali e delle famiglie di discontinuità e per la comprensione della cinematica di alcune faglie ad alto e basso angolo. il riconoscimento di diverse generazioni di superfici erosive sospese – alle quali è stato possibile attribuire un’età per correlazione morfostratigrafica con i vicini bacini del fiume mercure e del fiume sinni – dislocate dalle strutture tettoniche, ha permesso di valutare i tassi di sollevamento regionali e locali quaternari dell’area e di discriminare quantitativamente l’entità dei movimenti verticali associati alle diverse fasi morfoevolutive. la distribuzione plano-altimetrica di alcune generazioni di superfici di erosione relitte è stata, inoltre, confrontata con la quota sul livello del mare delle anomalie (punti di flesso o knickpoint) e di salti morfologici più pronunciati, non legati a morfoselezione, del profilo longitudinale di alcuni corsi d’acqua. come detto, pochi lavori a carattere geomorfologico e morfostrutturale hanno interessato in qualche modo i monti di lauria e dintorni: tra questi, si ricordano gli studi di bousquet & gueremy (1968), palmentola et al. (1980), l a r o c c a & s a n t a n g e l o (1991) e schiattarella et al. (1994), nei quali l’area è tuttavia presa in considerazione nell’ambito di contesti più ampi. i caratteri geologici sono stati oggetto della memoria di bonardi (1966) e, nel contesto di una trattazione più generale sul confine calabro-lucano, dello scritto di lorenzo et al. (2001). 2. inquadramento geologico dell’appennino meridionale e dell’area del confine calabro-lucano l’appennino meridionale è una catena montuosa con generale vergenza nord-orientale, formata in prevalenza da falde derivanti dalla deformazione del paleomargine apulo-africano mesozoico-terziario, sovrascorse e impilate sulla microplacca adriatica in subduzione. dall’oligocene terminale, la tettonica compressiva ha coinvolto, in un primo stadio di accrezione, la crosta ofiolitica dell’oceano liguride con la relativa copertura (knott, 1987; mauro & schiattarella, 1988; bonardi et al., 1988) e successivamente i terreni di piattaforma e bacinali del margine passivo continentale (pescatore et al., 1999; cello & mazzoli, 1999). la migrazione verso est del fronte dei sovrascorrimenti, accompagnata dalla sedimentazione di potenti successioni clastiche sintettoniche, è stata seguita da una estensione di retroarco che ha interessato diacronicamente in tempi plio-pleistocenici prima la fascia tirrenica e poi quella assiale dell’orogene sud-appenninico. evidenze di attività compressiva pleistocenica sono invece documentate nella porzione esterna della catena (pieri et al., 1997). in molti settori della catena, come per la grande morfostruttura del pollino – monti di lauria, la primitiva struttura contrazionale neogenica risulta smembrata da faglie plio-quaternarie trascorrenti ed estensionali con diversi andamenti. particolare importanza rivestono i lineamenti tettonici con orientazione n120°, in quanto responsabili della genesi e dell’evoluzione di molti bacini quaternari, compresi quelli dell’area del confine calabro-lucano (schiattarella, 1998). il segmento sudappenninico è anche caratterizzato da faglie normali a basso angolo con cinematica estensionale ed obliqua, che realizzano contatti tettonici anomali del tipo “giovane su vecchio”, interpretati in maniera assai differente dai diversi autori che se ne sono occupati (d’argenio et al., 1986; ietto & d’argenio, 1990; schiattarella, 1996; ferranti et al., 1996; schiattarella et al., 2006). il confine calabro-lucano rappresenta, secondo molti autori (dewey et al., 1989; turco et al., 1990; c i n q u e et al., 1993; c a t a l a n o et al. , 1993; schiattarella, 1996; 1998; marra, 1998), la fascia di fig. 1 schema geologico del confine calabro-lucano. geological sketch map of the calabria-lucania border. svincolo cinematico tra l’appennino meridionale e l’arco calabro, che si realizza attraverso lo sviluppo di una zona di taglio sinistra orientata all’incirca n120°. nell’area affiorano estesamente unità interne ofiolitifere, di norma in sovrapposizione tettonica su unità carbonatiche derivanti dalla deformazione della piattaforma appenninica. lungo il margine settentrionale della catena del pollino e dei monti di lauria si osserva tuttavia il sovrascorrimento fuori sequenza delle successioni carbonatiche mesozoiche sugli antistanti termini bacinali (schiattarella, 1996; 1998). le formazioni che compongono le successioni di mare basso ascrivibili alle unità che derivano dalla deformazione della piattaforma campano-lucana sono rappresentate da un complesso calcareo-dolomitico di età compresa tra il trias superiore ed il cretacico superiore, su cui poggiano in concordanza l’alternanza paleogenica calcareo-marnosa della formazione di trentinara o le calcareniti a glauconite della formazione di cerchiara del miocene inferiore. la successione è chiusa dalla formazione del bifurto, data da un’alternanza di età infra-mesomiocenica di argilliti, calcari marnosi, calcareniti, brecciole a macroforaminiferi rimaneggiati e quarzareniti, che rappresenta la fase di annegamento della piattaforma carbonatica. l’assetto tettonico della catena del pollino e dei monti di lauria-castelluccio deriva dallo smembramento della struttura contrazionale mio-pliocenica ad opera delle faglie prevalentemente quaternarie. un complesso pattern strutturale (turco et al., 1990) viene così prodotto nell’ambito della deformazione trascorrente, attiva dal pliocene superiore, le cui faglie sono successivamente riattivate in regime estensionale (ru s s o & schiattarella, 1992; schiattarella, 1998). studi morfostrutturali sui bacini di castrovillari (r u s s o & schiattarella, 1992), del mercure (schiattarella et al., 1994) e di morano calabro (perri & schiattarella, 1997) hanno consentito di porre un vincolo temporale all’attività trascorrente, che risulta ancora in essere durante il siciliano, mentre la tettonica estensionale, tuttora attiva, si sviluppa a partire dal passaggio tra il pleistocene inferiore e medio. 3. stratigrafia dei monti di lauria e depositi quaternari del valico di prestieri i monti di lauria sono costituiti da una serie di dorsali allungate in direzione n120°, in prevalenza costituite dai termini cretacici della successione carbonatica della piattaforma campano-lucana. i rilievi di serra rotonda e serra destra del tornesiello, ubicati lungo il margine nord-occidentale dell’area, e quelli di serra sardina e serra la nocara, che costituiscono rispettivamente il bordo occidentale e sud-occidentale del basso strutturale del valico di prestieri, sono caratterizzati da calcari con rudiste. dolomie altotriassiche formano invece l’ossatura dei rilievi di monte la spina e monte zaccana, alla cui sommità si rinvengono, in contatto tettonico per faglia normale a basso angolo, lembi calcarei giurassici e cretacici. alternanze terrigene mioceniche, in giacitura spesso caotica, sono conservate in aree di basso strutturale, come ad esempio in località la starsia, e formano parte del paesaggio collinare che 131caratteri morfotettonici dell’area ... si dipana lungo il pedemonte meridionale di serra rotonda. la formazione di trentinara costituisce, invece, parte della dorsale di serra pastorella, poco ad est dell’abitato di lauria. nell’area investigata, brecce di versante a matrice arrossata giacciono su ripiani erosionali sospesi rispetto al top deposizionale del riempimento fluvio-lacustre del mercure (ad esempio immediatamente ad est di monte zaccana). simili brecce, molto tettonizzate, si rinvengono a la starsia, in posizione di basso relativo e totalmente sganciate dai rilievi alimentatori. il deposito è caratterizzato da clasti carbonatici eterometrici da centimetrici a decimetrici, cementati, con matrice sabbiosa rossastra a luoghi molto abbondante. schiattarella et al. (1994) correlano questi depositi detritici, prodotti dal disfacimento dei primi versanti di faglia dell’area, alle facies prossimali delle “sabbie e conglomerati di serra corneta” (vezzani, 1967), attribuibili al pleistocene inferiore-medio. i sedimenti continentali quaternari del valico di prestieri affiorano, in prevalenza, alla base dei versanti meridionali di monte la spina e monte zaccana (fig. 2), a formare una serie di apparati conoidali che verso valle si interdigitano ai depositi lacustri mediopleistocenici del bacino del mercure. si tratta di ghiaie clasto-sostenute, solo localmente cementate, con elementi subarrotondati e sottili livelli sabbiosi, soprattutto nelle porzioni distali delle conoidi, che definiscono grossolanamente una clinostratificazione. il deposito è stato attribuito alla parte bassa del pleistocene medio da schiattarella et al. (1994). nell’area si rinviene un’altra serie di conoidi alluvionali, incastrate morfologicamente nelle precedenti, costituite da ghiaie massive con clasti carbonatici, in prevalenza dolomitici, a spigoli vivi di dimensioni da centimetriche a decimetriche; localmente si osservano grossi blocchi disposti caoticamente, che tendono a sparire nelle zone distali dove alle ghiaie si alternano livelli sabbiosi. a luoghi, le ghiaie sono caratterizzate da una matrice sabbiosa di colore rossastro. si osservano regolarmente anche intercalazioni di paleosuoli costituiti da argille limose brune con scheletro di varie dimensioni, che testimoniano ripetuti periodi di stasi nella sedimentazione alluvionale. lo spessore di questi depositi, rilevato da dati inediti di perforazione per ricerche idriche, raggiunge i 30 metri nelle zone distali. sulla base di considerazioni morfologiche, è possibile attribuire queste alluvioni alla parte alta del pleistocene medio. depositi colluviali e coni detritici del pleistocene superiore – olocene poggiano quasi ovunque sui depositi precedentemente descritti. 4. assetto tettonico e analisi strutturale per quanto concerne il fronte montuoso settentrionale dei monti di lauria-castelluccio, bonardi (1966) segnala la presenza di un piano di faglia che realizza il sovrascorrimento delle dolomie sui depositi terrigeni miocenici lungo il versante orientale della dorsale tempa arena bianca – monte lanzino, a nord di monte la spina. più estesamente, a nord della dorsale monte zaccana monte la spina serra rotonda, 132 schiattarella (1996) rileva il sovrascorrimento fuori sequenza dei terreni carbonatici sulle successioni pelagiche liguridi e lagonegresi. fenomeni di deformazione contrazionale o traspressiva di probabile età pliocenica sono stati riconosciuti anche lungo il fronte settentrionale della catena del pollino (schiattarella, 1996) e nei monti di maratea (lorenzo et al., 2001). alla sommità e lungo i versanti meridionali dei rilievi di monte la spina e monte zaccana si osservano le faglie trastensive a basso angolo che, come detto, realizzano la sovrapposizione di lembi calcarei giurassici o cretacici su dolomie altotriassiche. ietto & d’argenio (1990) interpretano i contatti “giovane su vecchio” come espressione di una tettonica estensionale sovrapposta alla tettonica contrazionale neogenica. ferranti et al. (1996) sostengono che l’estensione, avvenuta parallelamente all’asse della catena, si sia formata in risposta all’aumento della lunghezza e dell’inarcamento della catena, mentre perri & schiattarella (1997) relazionano le faglie a basso angolo e scivolamento obliquo, sulla base della compatibilità cinematica, al fagliamento trascorrente suprapliocenico-infrapleistocenico all’interno di zone di taglio orientate n120°. la differenza tra l’entità dei tassi di sollevamento quaternari (legati alla tettonica estensionale accoppiata con la risalita isostatica/termica dell’orogene e, in misura minore, allo stesso fagliamento trascorrente, attivo durante le prime fasi neotettoniche) ed i valori del carico tettonico sopportato dalle successioni mesozoiche, suggerisce invece di collegare geneticamente queste strutture a processi di denudamento tettonico attivi fin dalle fasi contrazionali di costruzione della catena (schiattarella et al., 2003; 2006). le superfici tettoniche a basso angolo con componente normale del movimento appaiono in ogni caso più vecchie delle faglie neotettoniche. una faglia normale ad alto angolo orientata all’incirca e-o, ad esempio, disloca un simile contatto lungo il versante meridionale di monte la spina (fig. 3). la dissezione ad fig. 2 carta geologica dell’area del valico di prestieri. nel riquadro in basso a destra, schema tettonico dell’area del confine calabrolucano (da schiattarella, 1998). geological sketch map of the valico di prestieri area. in the box below on the right, tectonic sketch map of the calabria-lucania boundary (after schiattarella, 1998). fig. 3 sezione geologica del versante meridionale di monte la spina. geological cross-section of the southern slope of mt. la spina. d. gioia & m. schiattarella 133 opera delle faglie quaternarie, la dissecazione del rilievo causata dai corsi d’acqua, susseguenti e non, e i processi di erosione selettiva sono infine responsabili dell’attuale configurazione “a lembi” delle sovrapposizioni tettoniche anomale. il versante sud-occidentale dei rilievi di serra sardina e serra rotonda è delimitato da una faglia subverticale normale orientata n160°, che accosta i calcari cretacici ai terreni miocenici. la dorsale monte rossino – serra la nocara, allungata in direzione n120°, appare invece dislocata trasversalmente a gradinata da una serie di faglie a direzione antiappenninica e componente prevalentemente normale, con aumento dei rigetti da se a no, come mostrato dalla distribuzione e dalla dislocazione delle superfici erosionali (vedi paragrafo successivo). immediatamente a sud della dorsale compresa tra lauria e castelluccio inferiore, si dipana per circa 15 km il basso strutturale del valico di prestieri, perimetrato da faglie orientate n120°, n-s e n30-40° e colmato da sedimenti continentali quaternari. i dati relativi alle mesostrutture fragili, relativi a tre stazioni di misura ubicate in figura 4, sono stati accorpati per famiglie azimutali (fig. 5). ciò ha permesso di identificare la fase tettonica più recente, a carattere distensivo ed asse tensile in direzione ne-so, responsabile della produzione delle faglie normali con orientazione media n150-160° che tagliano tutte le altre strutture della deformazione fragile. i piani n120-130° presentano spesso cinematica trastensiva destra, proprio in funzione della riattivazione in regime estensionale delle faglie trascorrenti. un simile motivo polifasico caratterizza anche le faglie meridiane e antiappenniniche con valori dell’angolo di pitch alquanto variabile, a testimonianza di ripetuti fenomeni di riattivazione di piani di discontinuità preesistenti. si registra, infine, la diffusa presenza di sistemi di joint estensionali all’incirca meridiani (fig. 5d), che hanno avuto una certa influenza nel condizionamento del reticolo idrografico. 5. analisi morfostrutturale le dorsali carbonatiche dei monti di lauria sono bordate da faglie ad alto angolo trascorrenti ed estensionali che hanno generato una serie di depressioni occupate dai depositi continentali quaternari e, in misura minore, dai sedimenti terrigeni miocenici. la depressione maggiore, aggradata da una serie di conoidi alluvionali quaternarie, si colloca tra i rilievi dolomitici di monte la spina e monte zaccana e quelli calcarei di monte rossino e serra la nocara. il basso strutturale de la starsia, meno esteso del precedente, caratterizza, invece, la parte nord-occidentale dell’area di studio ed è impostato nelle successioni terrigene mioceniche. in quest’area si ritrovano affioramenti di brecce in lembi più o meno estesi ascrivibili al pleistocene inferioremedio. diverse evidenze morfologiche (discontinuità altimetriche e plano-altimetriche dei versanti, versanti a sviluppo rettilineo, allineamenti di vette e doline) e anomalie del reticolo idrografico (corsi d’acqua a sviluppo rettilineo, gomiti e doppi gomiti fluviali, forre) mettono in luce, in accordo con l’analisi strutturale, sistemi di faglie distribuiti sistematicamente secondo le direzioni n-s, fig. 4 reticolo idrografico gerarchizzato con relativi valori degli indici morfometrici (nu = numero di corsi di ordine u; rb = rapporto di biforcazione; ndu = numero di corsi di ordine u che fluiscono in corsi di ordine u+1; rbd = rapporto di biforcazione diretto; r = indice di biforcazione) e ubicazione delle stazioni di misura strutturale. in tratteggio, i corsi d’acqua analizzati come indicatori morfotettonici del sollevamento quaternario. drainage network pattern with the relative values of morphometric parameters (nu = number of streams of the u order ; rb = bifurcation ratio; ndu = number of streams of u order flowing in u+1 order; rbd = direct bifurcation ratio; r = bifurcation index) and location map of the structural measurement stations. in dotted line, the channels analysed like morphotectonic indicators of the quaternary uplift. fig. 5 stereogrammi delle faglie rilevate nei terreni carbonatici, accorpate per famiglia azimutale. a) no-se; b) n-s; c) n30-60°; d) diagramma azimutale dei sistemi di frattura rilevati, alla mesoscala, nei carbonati meso-cenozoici. stereoplots of faults collected in carbonate rocks, separated on the basis of the azimuthal classes. a) nw-se; b) n-s; c) n30°-60°; d) rose diagram of the tectonic joint sets affected meso-cenozoic carbonates of the study area. caratteri morfotettonici dell’area ... 134 n120°, n30-50° e n160° (fig. 6). la realizzazione di alcuni profili morfostratigrafici, corredati da dati geologici e strutturali, ha dimostrato che queste strutture tettoniche sono responsabili della dislocazione delle diverse generazioni di superfici di spianamento relitte (figg. 7, 8 e 9). reticolo idrografico il reticolo idrografico dei monti di lauriacastelluccio (fig. 4) mostra, in generale, una bassa densità di drenaggio, insistendo principalmente sui carbonati che formano l’ossatura della monoclinale e sui depositi alluvionali quaternari caratterizzati da una buona permeabilità e da bassi gradienti di pendio. il deflusso delle acque mostra una migliore organizzazione in corrispondenza degli affioramenti delle dolomie bianche altotriassiche, soprattutto nella zona di testata e, in misura maggiore, laddove insiste sulle litologie delle successioni terrigene. l’organizzazione e il grado di maturità del reticolo può essere desunta dagli alti valori degli indici morfometrici (avena et al., 1967) dei quattro sottobacini del 4° ordine in cui è divisa l’area. in particolare, gli alti valori dell’indice di biforcazione delle aste di alto ordine gerarchico (valori di 1,4 e 2 per il 2°/3° ordine e il 3°/4° ordine, rispettivamente) sono probabilmente dovuti alla diffusa presenza di segmenti anomali nei corsi d’acqua maggiori ed indicano una struttura del reticolo alquanto disorganizzata, propria delle aree in cui l’evoluzione del reticolo è controllata dalla struttura (firpo & spagnolo, 2000). l’analisi su base statistica delle direzioni di deflusso delle acque (fig. 6) ha messo in luce alcuni andamenti preferenziali nella direzione dei corsi d’acqua. il diagramma “a rosetta” relativo alle aste di basso ordine gerarchico (1° e 2° ordine, fig. 6d) mostra un massimo assoluto attorno alla classe meridiana, oltre ad un picco meno sviluppato in corrispondenza della classe n90-100°. per quanto concerne le sole aste del 1° ordine, anche la classe n30-40° appare statisticamente significativa (fig. 6a). il diagramma azimutale delle fratture ad alto angolo (costruito sulla base delle 331 misure effettuate nelle tre stazioni riportate in fig. 4) mostra l’esistenza di un chiaro massimo assoluto in corrispondenza dell’andamento meridiano, oltre ad un picco meno sviluppato attorno alla classe n90-100° (fig. 5d). la geometria del sistema di fratture è pertanto rappresentata nell’intera area da due famiglie ortogonali, come rilevato alla mesoscala, ad esempio, a serra la nocara. la buona corrispondenza tra le direzioni di deflusso preferenziale delle aste di basso ordine gerarchico e quelle dei sistemi di frattura dimostra che la nascita e lo sviluppo dei corsi d’acqua minori sono fortemente controllati dallo stato di fratturazione dell’ammasso roccioso carbonatico. il massimo relativo n3040° relativo alle aste del 1° ordine sembra invece più semplicemente relazionato alle direzioni di massima pendenza (il trend è ortogonale all’allungamento morfostrutturale della depressione). le aste del 3° ordine si distribuiscono intorno a più direzioni. nonostante una certa dispersione dei dati, si possono riconoscere i trend n-s, n40-50°, n90-100° e n140-150°. è da notare che alcune direzioni preferenziali di deflusso delle aste del 3° ordine corrispondono, almeno in parte, agli andamenti dei morfolineamenti più fig. 6 a) diagramma azimutale delle aste del 1° ordine; b) diagramma azimutale delle aste del 2° ordine; c) diagramma azimutale delle aste del 3° ordine; d) diagramma azimutale delle aste del 1° e del 2° ordine; e) diagramma azimutale dei morfolineamenti di origine tettonica (base dei versanti di faglia, corsi d’acqua rettilinei, gomiti fluviali, ecc.) dell’area; f) diagramma azimutale costruito sulla base della lunghezza dei morfolineamenti di origine tettonica (modulo unitario di 500 m). a) rose diagrams of the i order streams; b) rose diagrams of the ii order streams; c) rose diagrams of the iii order streams; d) rose diagrams of the i and ii order streams; e) rose diagrams of the tectonic lineaments of the area; f) rose diagrams constructed on the basis of the length of tectonic lineaments (unit module = 500 m). lunghi dell’area e, in particolare, ai lineamenti con orientazione n-s, e-o e n130-140° (cfr. figg. 4 e 6f). i profili longitudinali di alcuni corsi d’acqua (fosso rubbiolo e torrente salice, fig. 10) mostrano alcuni flessi e salti non legati a morfoselezione, dovuti alla risposta dei corsi d’acqua al sollevamento recente (boenzi et al., 2004; molin et al., 2004), che appaiono in accordo con la distribuzione altimetrica delle superfici erosionali (figg. 8 e 9; cfr. sottoparagrafo successivo). i tratti di corsi d’acqua a sviluppo rettilineo, i segmenti rettilinei di forre (torrente caffaro, fosso della zaccana e vallone buona zita), i gomiti e i doppi gomiti fluviali, unitamente ai versanti a sviluppo rettilineo, alle faccette triangolari ed alle discontinuità altimetriche e plano-altimetriche dei crinali, hanno permesso di individuare famiglie di faglie, la cui espressione morfologica è stata anche riconosciuta dall’analisi di aerofoto e verificata sul terreno, distribuite attorno alle classi azimutali d. gioia & m. schiattarella n-s, n50-60°, n90-100°, n120°-n150°. il trend meridiano è chiaramente prevalente nell’area, pur risultando significativamente presenti anche gli andamenti compresi nei quadranti no e se, come meglio mostrato dal diagramma costruito in funzione della lunghezza dei morfolineamenti (fig. 6f). in particolare, le faglie con orientazione n120°, che peraltro rappresentano elementi strutturali a valenza regionale (schiattarella, 1998), hanno esercitato una certa influenza solo sui corsi d’acqua di alto ordine gerarchico, come ad esempio si può rilevare alla base del versante nord-orientale di monte fossino, dove il fosso rubbiolo si dispone secondo tale andamento con un percorso pressoché rettilineo (fig. 4). 135 fig. 7 schema morfostrutturale dell’area dei monti di lauria e del valico di prestieri. morphostructural map of the lauria mts – prestieri trough area. caratteri morfotettonici dell’area ... superfici erosionali e deposizionali molti dei versanti di faglia dell’area investigata sono caratterizzati da profili convessi o da profili complessi realizzati da superfici erosionali a debole pendenza sospese rispetto all’attuale livello di base che raccordano tratti di versante ad inclinazione costante ma diversa per i differenti segmenti. entrambi i casi testimoniano l’evoluzione polifasica del rilievo, prodotta dall’alternanza di momenti di sollevamento e di fasi erosive. durante antichi stazionamenti dei livelli di base locali dell’erosione, la morfogenesi ha prodotto superfici di spianamento o cenge e ripiani erosionali, scolpiti in 136 fig. 8 distribuzione plano-altimetrica dei lembi relitti di superfici erosionali e deposizionali e principali morfolineamenti di origine tettonica. spatial arrangement of the relict erosional and depositional surfaces and main tectonic lineaments of the area. d. gioia & m. schiattarella 137 fig. 9 profili morfostratigrafici, integrati da dati geologico-strutturali, che intercettano i diversi ordini di superfici erosionali e deposizionali relitte morphostratigraphic sections showing the different orders of relict erosional and depositional surfaces of the area. discordanza prevalentemente nelle unità carbonatiche mesozoiche, ma anche nelle successioni terrigene mioceniche e nei depositi continentali plio-quaternari. i singoli lembi hanno dimensioni variabili da poche centinaia di metri ad alcuni chilometri quadrati, pendenze inferiori ai 7-8° e bassa energia di rilievo. i lembi alle quote più caratteri morfotettonici dell’area ... elevate si configurano come relitti di più ampie superfici erosionali mentre quelli situati a quote più basse presentano caratteristiche che sembrano indicare un modellamento più simile alle condizioni prodotte dal reticolo idrografico attuale. nell’area dei monti di lauria-castelluccio sono stati riconosciuti quattro ordini di superfici di erosione sospese rispetto al fondovalle attuale, indicative di altrettanti paleolivelli di base locali dell’erosione, distribuite tra 1600 m e 700 m di quota s.l.m.; a ciascun ordine di superfici spianate è stata attribuita un’età di disattivazione (riferita al momento in cui viene dislocata una superficie di erosione, si deprime il livello di base e si innesca un approfondimento verticale che si sviluppa con maggiore energia rispetto all’erosione laterale) sulla base dei dati di letteratura, con particolare riferimento alle aree del bacino del mercure e della catena del pollino (schiattarella et al., 1994; 2006). l’elemento geomorfologico più antico (s1) è rappresentato dai resti di un antico paesaggio erosionale sub-pianeggiante di estensione regionale (“paleosuperficie” in capaldi et al., 1988) posto in posizione sommitale sui monti di lauria-castelluccio, a cui è stata attribuita un’età di disattivazione compresa tra il pliocene superiore ed il pleistocene inferiore (schiattarella et al., 2003; boenzi et al., 2004). i lembi della superficie sommitale, scolpiti in discordanza sui terreni carbonatici e distribuiti a quote superiori ai 1300 metri, sono fortemente rimodellati e presentano forme tipiche di morfogenesi in ambiente fluvio-carsico, come sulla sommità del monte rossino, dove la s1 si presenta debolmente ondulata e con tracce di erosione subaerea quali incisioni e doline. i lembi che formano la cima di serra rotonda e di monte la spina sono invece ridotti in estensione dal modellamento retrogrado dei versanti e la preesistente spianata è testimoniata solo dall’andamento sub-orizzontale dei crinali. l’originaria genesi della paleosuperficie auctt. è stata attribuita a processi di modellamento in ambiente marino-transizionale (boenzi et al., 2004), le cui tracce risultano obliterate dal successivo rimodellamento in contesti morfoclimatici continentali. la sovrapposizione di diversi episodi morfogenetici permette di considerare la superficie s1 come una superficie di spianamento poligenica; inoltre essa è da considerare anche policiclica, a causa della riattivazione tettonica del ciclo erosivo. i lembi della superficie sommitale sono delimitati da un versante di faglia che si raccorda ad un ampio paesaggio di erosione (superficie di erosione s2), riconducibile ad un modellamento composito di tipo fluviocarsico, che insiste sia sul substrato carbonatico che, a luoghi, sulle “brecce antiche” di bousquet et al. (1969). i lembi della s2 hanno dimensioni abbastanza ridotte e si distribuiscono attorno a quote comprese tra 1300 ed i 1000 metri s.l.m.; il carattere poligenico della superficie s2, alla quale è possibile attribuire un’età di disattivazione compresa nell’intervallo temporale 1.4-1.1 ma (in cui ricade la crisi tettonica “emiliana”, documentata nell’area da russo & schiattarella, 1992), è evidenziato dalla sovrapposizione di forme riconducibili a processi di erosione lineare su elementi morfologici legati ad un modellamento di tipo carsico. la superficie s3 presenta caratteristiche diverse rispetto ai paesaggi più antichi in quanto si configura come un glacis d’erosione o di accumulo che si raccorda alle superfici s1 e s2 tramite versanti di faglia regolarizzati, profondamente inciso dai corsi d’acqua e sospeso rispetto al fondovalle attuale. i lembi della superficie s3 sono i più ampi e diffusi dell’area di studio, distribuiti tra gli 800 e i 1000 metri di quota e frequentemente modellati sui calcari cretacici. l’età di disattivazione attribuibile alla superficie s3 è di circa 0.8-0.7 ma, poiché essa appare correlabile con il top deposizionale delle brecce di misciarolara, affioranti alla terminazione nord-orientale della dorsale dei monti di lauria e attribuite da schiattarella et al. (1994) al pleistocene inferiore-medio. la superficie s4 coincide con il top deposizionale delle conoidi alluvionali recenti dell’area del valico di prestieri ed è sospesa a poche decine di metri rispetto al fondovalle attuale. l’incisione di questo elemento ad opera del torrente salice è iniziata presumibilmente a 0.13-0.11 ma circa, in seguito al vistoso approfondimento del reticolo idrografico del contiguo bacino del mercure, aggradato da sedimenti lacustri post-mindeliani, a sua volta innescato dal sollevamento “tirreniano”. i profili morfometrici qui presentati (fig. 9) mostrano chiaramente il carattere erosionale delle superfici poste a quote più elevate, scolpite in discordanza rispetto alla giacitura del substrato carbonatico. l’attività delle faglie ha dislocato e sospeso le superfici di spianamento, attivando nuovi cicli morfogenetici, probabilmente caratterizzati anche da condizioni morfoclimatiche diverse, e ne ha determinato il carattere poli138 fig. 10 anomalie, non legate a morfoselezione, nei profili longitudinali del torrente salice e del fosso rubbiolo, correlabili ai livelli di base locale dell’erosione riconosciuti attraverso le superfici relitte. knickpoints of the longitudinal profiles of salice and rubbiolo streams, correlated with the same orders of erosional and depositional surfaces. d. gioia & m. schiattarella genico e policiclico. altre faglie sono invece rasate, e dunque fossilizzate, dal modellamento della superficie (si veda ad esempio il profilo a-a’). i rigetti verticali maggiori si registrano lungo i versanti che raccordano le superfici s2 con quelle s3. localmente si può osservare come alcuni lembi originariamente orizzontali siano basculati e ruotati contro monte dall’attività tettonica. al fine di individuare i paleolivelli di base locale dell’erosione, sono stati anche eseguiti alcuni profili longitudinali a scala di dettaglio (1:5000) lungo corsi d’acqua minori dell’area in esame (fig. 10). la risposta di un corso d’acqua al sollevamento recente porta all’alterazione del suo profilo attraverso la formazione di un flesso (knickpoint), in corrispondenza dello stazionamento degli antichi livelli di base locali, che si conserva nel medio termine in litologie lapidee. la presenza di piccoli terrazzi strath e cenge erosionali in roccia in coincidenza dei punti di flesso corrobora tale ipotesi. gli intervalli di quota delle anomalie ed i salti non legati a morfoselezione dei profili longitudinali dei corsi sono stati quindi confrontati con quelli delle superfici di erosione. la correlazione altitudinale, operata per settori omogenei, mostra una buona corrispondenza tra gli indicatori di paleolivelli di base più recenti. la differenza di quota tra le anomalie nel profilo longitudinale del torrente salice e quelle del fosso rubbiolo, che mostra il paleolivello di base locale corrispondente alla superficie s3 a quote maggiori, può essere imputata al fatto che quest’ultimo intercetta alcune faglie che non incrociano, invece, il corso del torrente salice. 6. tassi di sollevamento l’età e la distribuzione altimetrica dei diversi ordini di superfici erosionali dell’area di studio hanno permesso di calcolare i tassi di sollevamento e l’entità dei rigetti verticali prodotti dalle faglie. il grafico quota/età (fig. 11) evidenzia che nel quaternario l’energia del rilievo è stata acquisita in modo pressoché costante. si osserva solo un leggero aumento della velocità dell’acquisizione del rilievo (maggiore pendenza della curva) dalla metà del pleistocene inferiore all’inizio del pleistocene medio. i tassi di sollevamento regionale vanno ad assestarsi su valori medi di circa 1 mm/a, con una crescita costante dal pliocene terminale al pleistocene medio. i tassi di sollevamento locale, che coincidono in linea di massima con il tasso di scivolamento lungo le faglie dell’area, mostrano valori medi intorno a 0,5 mm/a fino al pleistocene medio per diminuire sensibilmente in seguito. il decremento dei tassi di sollevamento durante il pleistocene superiore è in accordo con i dati provenienti da altre zone dell’appennino meridionale e può essere suffragato, nell’area del confine calabro-lucano, dai dati paleosismologici e dalla scarsità di evidenze di deformazione nei depositi più recenti (ferreli et al., 1996; perri & schiattarella, 1997). la dislocazione tettonica delle superfici spianate è stata utilizzata per calcolare il tasso di scivolamento lungo la faglia che borda a sud il rilievo di monte zaccana e che rappresenta forse il principale elemento strutturale dell’area. il rigetto verticale totale cumulato nel corso del quaternario è di circa 700 metri, con uno slip rate di 0,5 mm/a. 7. conclusioni sulla base dei dati morfostratigrafici e morfostrutturali acquisiti in questo studio, la storia tettono-evolutiva dell’area dei monti di lauria e del valico di prestieri può essere riassunta nel modo di seguito illustrato e rappresentato schematicamente in figura 12. le strutture legate alla tettonica contrazionale oligo-miocenica (pescatore et al., 1999) che non avevano prodotto un rilievo apprezzabile, almeno nell’area investigata vengono tagliate e dislocate, probabilmente durante il pliocene inferiore, da piani di taglio a basso angolo con cinematica normale o obliqua. l’ipotesi più probabile, avallata anche dal confronto tra i dati relativi ai tassi di sollevamento quaternari e dei carichi tettonici stimati per l’area dei massicci carbonatici silentini, per le unità interne ofiolitifere e per il nucleo profondo della catena appenninica (schiattarella et al., 2003; 2006; aldega et al., 2005; di leo et al., 2005), è che si tratti di strutture generate da processi di denuda139 fig. 11 rappresentazione grafica dei tassi di sollevamento quaternari regionale e locale. il tasso di scivolamento della faglia che borda, con andamento all’incirca n120°, il versante meridionale di monte zaccana è stato calcolato sulla base dell’entità dei rigetti verticali cumulati dalle superfici erosive sospese. diagrams showing quaternary regional and local uplift rates. slip rates of the fault bordering the southern slope of mt. zaccana has been calculated on the basis of the erosional surfaces displacement. caratteri morfotettonici dell’area ... mento tettonico, attivati e guidati dalla topografia della catena acquisita durante la deformazione contrazionale tardoe post-miocenica, come recentemente sostenuto da schiattarella et al. (2003; 2006). il principale vincolo cronologico per determinare l’intervallo di attività del denudamento tettonico è rappresentato dall’età di emersione della catena nel settore assiale (non prima del tortoniano inferiore, età più recente dei depositi terrigeni miocenici dell’area, cfr. aldega et al., 2005). inoltre, i rapporti intercorrenti con la paleosuperficie auctt. permettono in ogni caso di considerare queste strutture nei carbonati mesozoici più antiche del pliocene superiore e di collocarle perciò nell’ambito della deformazione infrapliocenica. le faglie a basso angolo con componente normale, responsabili dei contatti tettonici “giovane su vecchio” (ietto & d’argenio, 1990), si configurano pertanto come dei relitti morfostrutturali antichi, in posizione apicale rispetto ai versanti di faglia pleistocenici, dislocati dalla tettonica fragile plio-quaternaria e isolati dall’erosione lineare. successivamente ai fenomeni di denudamento tettonico (e quindi probabilmente a partire dal pliocene medio) ha luogo il sovrascorrimento fuori sequenza dei terreni carbonatici sulle unità interne, che lungo il bordo settentrionale della catena del pollino è interpretabile per quanto concerne la sua evoluzione infrapleistocenica e sulla base di considerazioni cinematico-giaciturali (schiattarella, 1996) come legato alla rotazione antioraria di circa 30° lungo l’asse verticale di blocchi rigidi individuati dall’intersezione di faglie trascorrenti sinistre con orientazione n120° e faglie trascorrenti destre ad andamento meridiano. i modesti rigetti verticali prodotti da questa tettonica a scala regionale promuovono il modellamento di una morfologia matura (paleosuperficie auctt.) che viene dislocata tra il pliocene superiore ed il pleistocene inferiore, in risposta al perdurare del regime di trascorrenza sinistra lungo i lineamenti n120° (russo & schiattarella, 1992; perri & schiattarella, 1997). la direzione di estensione compatibile con questo campo deformativo genera faglie dirette o trastensive ad andamento n30-60°, che producono deboli rigetti verticali ed individuano bassi morfostrutturali all’interno dei quali si accumulano i depositi clastici (“brecce antiche”) derivanti dalla degradazione dei primi versanti di faglia. nel passaggio tra il pleistocene inferiore e medio il nuovo regime estensionale ad asse ne-so genera faglie normali orientate circa n150-160° e riattiva le faglie trascorrenti n120° con movimenti obliqui o normali, mentre quelle antiappenniniche e meridiane assolvono passivamente al compito di trasferire la deformazione in settori adiacenti (schiattarella et al., 1994; schiattarella, 1998). in questa fase i rilievi carbonatici dei monti di lauria-castelluccio acquisiscono i massimi rigetti verticali e il basso del valico di prestieri, che guadagna spazio di accomodamento per i sedimenti, viene riempito dai depositi di conoide alluvionale. tale stadio deformativo perdura durante il pleistocene medio in quanto sblocca la superficie s3 dell’area di studio e tettonizza i depositi lacustri del bacino del mercure (schiattarella et al., 1994). l’attività delle faglie sembra invece diminuire nel pleistocene superiore: i depositi di conoide altopleistocenici non presentano evidenze di deformazione, in accordo con i dati paleosismologici (ferreli et al., 1996), e si assiste solo alla reincisione dei depositi alluvionali altopleistocenici e alla deposizione dei depositi detritici recenti. il riconoscimento di diversi ordini di superfici di spianamento poligeniche e polifasiche ha permesso di determinare l’entità dei movimenti verticali quaternari. l’energia del rilievo è stata acquisita nell’area tramite la congiunzione del sollevamento regionale e dell’attività delle faglie ad alto angolo, come del resto accaduto per l’intero appennino meridionale, vistosamente smembrato dagli eventi neotettonici. il tasso di sollevamento regionale si attesta attorno a 1 mm/a, mentre la velocità di scivolamento delle superfici delle faglie principali è mediamente di 0,5 mm/a. le evidenze morfostrutturali permettono di affermare che gli slip rate delle faglie dell’area si distribuiscono intorno a valori più elevati nell’intervallo temporale relativo al passaggio pleistocene inferiore-medio. il sollevamento tettonico ed i periodi di stasi sono stati registrati anche dai corsi d’acqua dell’area, attraverso la formazione di knickpoint in corrispondenza delle quote dei paleolivelli di base locale dell’erosione più recenti. le direzioni preferenziali di deflusso 140 fig. 12 sequenza morfo-tettonoevolutiva dell’area di studio dal miocene medio al quaternario. legenda: i segni + e indicano rispettivamente i blocchi rialzati e ribassati, le aree con puntinato i depositi quaternari, le linee diritte con frecce o tratti rappresentano rispettivamente le faglie trascorrenti e dirette, le linee tratteggiate le faglie di trasferimento, le linee curve con triangoli i sovrascorrimenti, le linee curve con frecce e trattini le faglie normali a basso angolo. morphotectonic evolutionary sequence of the study area from middle miocene to quaternary. legend: signs + and show uplifted and downthrown blocks, dotted parts represent the quaternary deposits, straight lines with arrows or dashes are respectively strike-slip and normal faults, broken lines are transfer faults, curved lines with triangles represent thrusts, curved lines with arrows and dashes represent low-angle normal faults. d. gioia & m. schiattarella delle acque coincidono inoltre con le direzioni delle strutture tettoniche recenti. in particolare, lo sviluppo del reticolo risente fortemente dell’influenza della tettonica mediopleistocenica: i corsi d’acqua di basso ordine gerarchico sono impostati sulle vie di minore resistenza che nelle litologie carbonatiche sono rappresentate tipicamente da fratture ad alto angolo che pervadono l’ammasso roccioso, mentre le aste di ordine maggiore si distribuiscono lungo i principali lineamenti strutturali, secondo percorsi pressoché rettilinei e valli ripide e strette. la fase tettonica mediopleistocenica determina anche un’ondata di erosione regressiva che produce un generale approfondimento dei corsi d’acqua, il terrazzamento dei depositi conoidali del valico di prestieri e l’incisione del substrato. a questo generale approfondimento del reticolo sono collegati anche i fenomeni di esumazione della base di alcuni versanti di faglia, la genesi di numerose forre e probabilmente qualche fenomeno di cattura fluviale (p.es. alto corso del t.te caffaro). è interessante notare, in conclusione, come l’attuale assetto geomorfologico di un’area relativamente poco estesa sia il risultato della stessa sommatoria di avvenimenti tettonici, deposizionali ed erosivi che hanno interessato l’intera zona assiale dell’appennino meridionale e che, pertanto, anche da simili aree si possono ricavare informazioni atte a verificare la congruenza di modelli evolutivi relativi a contesti più ampi. ringraziamenti 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(1990) la tettonica plio-pleistocenica del confine calabro-lucano: modello cinematico. mem. soc. geol. it., 45, pp. 519-529. vezzani l. (1967) osservazioni sul bacino lacustre del fiume mercure . atti acc. gioenia sc. nat. catania, 18, pp. 229-235. 142 ms. ricevuto il 6 giugno 2006 testo definitivo ricevuto il 17 ottobre 2006 ms. received: june 6, 2006 final text received: october 17, 2006 d. gioia & m. schiattarella imp.panizza&piacente geomorphosites: a bridge betwenn scientific research, cultural integration and artistic suggestion mario panizza & sandra piacente dipartimento di scienze della terra, università degli studi di modena e reggio emilia largo s. eufemia, 19 – 41100 modena pit@unimore.it; piacesan@unimore.it abstract: m. panizza & s. piacente, geomorphosites: a bridge betwenn scientific research, cultural integration and artistic suggestion. (it issn 0394-3356, 2005). the authors start with noting that the geological aspects has not yet assumed its proper value as a cultural asset. this seems to derive above all from a static approach and museum-like view of our geological heritage current in society, that have limited its meanings and potentialities considerably. now there is a very important occasion for re-launching geology as a cultural and social discipline though some activities that can be summarised in three main fields. scientific research on geosites which are one of the components of the cultural heritage of a given territory as well as works of art, fauna and flora etc. cultural integration between the geological-geomorphological aspects of a territory and the other landscape components (biological, historical, artistic etc.) within a concept of “integrated cultural landscapes”. artistic suggestion of those geological sites which have been source of literary, pictorial, musical etc. inspiration. for each of the above mentioned fields some different characteristic examples are highlighted. riassunto: m. panizza & s. piacente, geomorfositi tra ricerca scientifica, integrazione culturale e suggestione artistica. (it issn 0394-3356, 2005). gli autori partono dalla constatazione che gli aspetti geologici non hanno ancora assunto il valore di bene culturale. ciò sembra derivare sopratutto da una percezione statica e da una visione museografica con cui il patrimonio geologico viene tuttora percepito, che ne limitano fortemente i significati e le potenzialità. attualmente si sta presentando un’occasione molto importante per il rilancio della geologia che potrebbe e dovrebbe trovare inedite vocazioni culturali e sociali. le attività per tale rilancio possono essere schematicamente raggruppate in tre campi principali. ricerca scientifica dei geositi, che rappresentano una delle componenti del patrimonio culturale di un dato territorio così come monumenti, flora, fauna etc. integrazione culturale tra gli aspetti geologico-geomorfologici di un territorio e le altre componenti del paesaggio (biologica, storica, artistica etc.) nel concetto di “paesaggio culturale intergrato”. suggestione artistica di quei siti geologici che sono stati fonti di ispirazioni letterarie, pittoriche, musicali etc. di ciascuno dei campi sopra citati vengono illustrati alcuni esempi significativi. keywords: geomorphosites, scientific research, cultural integration. parole chiave: geomorfositi, ricerca scientifica, integrazione culturale. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 3-10 1. forward in a modern society like ours, where environmental problems are usually pressing and urgent, earth sciences still occupy a marginal role. this is hardly justifiable if we consider the importance they have actually had and will have in the history and development of life and civilisation. it is therefore necessary to find new paths and strategies in order to spread better information and communication which can fill this gap. in particular, the geological aspect has not yet assumed its proper value as a cultural asset. therefore, before proposing its conservation and appraisal, its status must first be recognised and new strategies for spreading information must be found, which can reach not so much in the scientific and institutional world but rather society at large. the static approach and museum-like view of our geological heritage current in society so far, have limited its meanings and potentialities considerably. furthermore, the nearly total lack of a tradition of communication and education in geological sciences has contributed to causing a delay both in understanding and in arousing an awareness of the cultural value of geology in society. this is a very important occasion for re-launching geology as a cultural and social discipline. we should therefore define a geological space where nature itself can offer inspirations for finding the best relationship with man, the right “distance” (secchi, 2001): metric, visual, sensorial and symbolic or suggest new practices for territorial management. this need has become ever more felt in the past few years which have been characterised by a marked democratisation of the space around us and its usage. new impulses and expectations are opening up new ways, hardly ever followed before, as confirmed by the activities of ecologist associations, public boards, protection agencies and government norms. all this has 4 m. panizza & s. piacente been accompanied by research programmes carried out at a national and international level, such as the research programme activated by unesco, progeo, the international association of geomorphologists and confirmed in their provisions, in particular in articles nos. 1 and 6 of the “european convention on landscape” (florence, 2000). all the interventions, perspectives and goals of these activities can be summarised in three main fields. scientific research on geosites which are one of the components of the cultural heritage of a given territory as well as works of art, fauna and flora, etc. cultural integration between the geological-geomorphological aspects of a territory and the other landscape components (biological, historical, artistic etc.) within a concept of “integrated cultural landscape”. artistic suggestion of those geological sites which have been the source of literary, pictorial, musical etc. inspiration. the above described points will be developed by making reference to the experiences so far achieved by the authors at a local, national and international level. these experiences have mainly interested sites of geomorphological interest which have been defined as “geomorphosites” (panizza, 2001; panizza & piacente, 2003). 2. scientific research basic investigations have been carried out and applied research projects have been implemented or are still in progress with funds from italian ministries, the european union and by means of conventions with public boards. investigations, which started some 20 years ago, have been developed with the following aims: to emphasise and assess the relationships between physical landscape and quality of the environment and between development of geomorphological knowledge and socioeconomic development (panizza, 1988; panizza, 1989a; panizza, 1990a; panizza, 1990b; panizza, 1990c; panizza & piacente 1991; panizza, 1992b; panizza & piacente, 1993; panizza, pellegrini & pozzi (1993), panizza & piacente, 1999a; panizza & piacente, 1999b; piacente, 1999a; piacente, 1999b; panizza & piacente, 2000; panizza, 2001; panizza, 2003; piacente, 2003; piacente & poli, 2003; panizza & piacente, 2003). to define a methodology for the identification and census of geosites (panizza, 1992b; carton et al., 1994; panizza & piacente, 1999a, 1999b; bertacchini et al., 1999; bertacchini et al., 2001; panizza & piacente, 2003). to present and test in different environmental contexts a catalogue card linked to a computer-based archive (bertacchini et al., 1999; bertacchini et al., 2002a; piacente & poli, 2003). to provide an example of geo-referenced mapping sites within a given regional territory (castaldini et al., 1997; bertacchini et al., 1999; piacente et al., 2001). to set up a thematic itinerary, where a geosite can be transformed from a “geological object” into a “cultural asset” available to the public (panizza & spampani,1988, 1989; panizza 1989a, panizza 1989b; piacente 1989; carton & panizza,1991; piacente et al., 2000; bertacchini et al., 2002b; piacente et al., 2001; panizza & piacente, 2003). to organise educational projects in which the curricula carried out can offer the opportunity to bring students from all levels closer to field geology, during their normal period of cultural formation (piacente & soldati, 1989; piacente & giusti, 2000; panizza & piacente, 2001; bertacchini et al., 2002; piacente & poli, 2003, panizza & piacente, 2003). starting from these observations, our investigations have tried to turn the complex environment-geological asset system into a language accessible to the widest possible public, even in unusual ambits, such as the elderly, the disabled and young children, making use of local forces and resources and involving young and old in a privileged role: the former in the educational and professional phase, and the latter in conveying experiences and values, using the past as a preparation for the future. 3. cultural integration a landscape is to be appreciated with all its physical, biological, historical, architectonic etc. components, it can then be considered a primary cultural asset resulting from complex relationships. there is now the awareness that only an in-depth understanding of all the environmental components of a territory and their history can lead to proper conservation and management initiatives. naturally, the first source of understanding lies in the territory itself, with its geological structure and its morphological features. then we have to consider interventions made by man on the natural elements. lastly the archaeological, historical, socioeconomic, etc. elements must be fully taken in. therefore, the relationships and reciprocal influences between physical landscape and cultural assets (here considered in a strict sense, that is the above mentioned archaeological, historical, architectonic etc. assets) should be identified. as regards research methodology, five operational phases can be identified (panizza & piacente, 2000). the first phase consists of a physical setting of the territory in which the cultural (i.e. historical and architectonic) asset is located, in terms of geological and geomorphological evolution, in terms of resources (raw materials, lithology, morphology, hydrology etc.) and in terms of stability and, therefore, of natural hazards (disarray processes, landslides, floods, earthquakes, volcanic eruptions etc.). subsequently, the geomorphological causes which have conditioned the location of a cultural asset should be taken into account. in fact, if the construction of a historicalarchaeological site generally responds to the socioeconomic needs (housing, religious practices, defence etc.) of a given community over a given territory, at the same time the particular location selected is chosen also on the basis of its environmental characteristics. among these, for example, the lithological characteristics, owing to the availability of building materials, the hydrological characteristics, owing to the presence of a watercourse, the geomorphological characteristics, owing to the presence of a naturally sheltered area or a look-out point and so on. subsequently, it will be necessary to assess whether a given cultural asset may be affected by natural hazards (in our case, geomorphological hazards) and, consequently, subject to risks. in this case, defence and mitigation interventions must be planned. furthermore, it should be assessed whether the possible fruition of a cultural asset – for example following social or tourism initiatives – may bring about negative consequences for the natural, in particular for the geomorphological, environment in terms of environmental impact. finally, it should be taken into account that the correct management of a historical-archaeological asset cannot be separated from its knowledge integrated in the surrounding environment (panizza & piacente, 1991; 1999a). in this way the proper fruition of both aspects will be implemented, with a positive spin-off from the socioeconomic viewpoint, also as regards conservation and appraisal. this sort of activity, including all promoting and protecting initiatives and measures, must necessarily be based on interdisciplinary studies and multiple management of environmental education initiatives. another significant example is offered by montsaint-michel. this is a granite islet, located in the bay bearing the same name near the mouth of the couesnon river. on top of the islet, various monumental buildings were constructed, making it one of the most interesting and typical places of northern france (fig. 1). at the centre of this historical-artistic complex there is a benedictine abbey overlooking the cliff. the original core of this monumental area was an oratory dating from the year 708, which was dedicated to st. michael. later, a carolingian church was built (x century), a romanesque abbey (xi-xii century), a monastery and a gothic cloister and a choir (xiii to xv century). one of the most singular characteristics of this site is its cyclic isolation from the mainland caused by the alternation of low and high tide. this is a magic, constantly transforming landscape, where another “tide” has been flowing in for centuries: first pilgrims, and nowadays, prevalently, tourists. like all bays, even montsaint-michel bay is subject to silting. this natural process has increased with time owing to various human activities carried out through the centuries: dams, canals and locks built on the course of the river couesnon resulted in a decrease of its stream velocity and flow rate. as a consequence, this watercourse lost the energy necessary to evacuate the debris materials deposited at its mouth causing also a decrease of the ebb current. a further consequence of this activity was the development of a particular marine flora which retains 5geomorphosites: a bridge between ... the sediments in the bay. furthermore, the road on an artificial embankment which links the little island to the mainland has modified the original aspect of the area. an interdisciplinary study involving hydraulics, geomorphology, biology etc., and laboratory analysis utilising a model of the environmental situation have allowed a solution to be identified for re-establishing the original conditions. a mobile dam able to control the runoff of the r. couesnon will be built and one of its branches will be diverted in order to decrease the amount of solid load towards mont-saint-michel. in this way the combined sea/river action will be enhanced in order to increase the ebb current which, in turn, would wash away part of the debris. the embankment road will be substituted with an “ecological shuttle” on a footbridge. within forty years, the sea floor between the islet and the mainland should be lowered by about 70 m and the surrounding marine floors should gain some 50 ha. all this should take place without compromising the traditional activities of the inhabitants, such as mussel farming and fishing on foot. the unique landscape of this special site will therefore be recreated “where sea and man have united to give origin to this masterpiece of human heritage”. in order to negotiate more specifically the relationships between geomorphology and cultural assets (in a strict sense), three types of conceptual approaches may be identified and, consequently, three types of methodological approaches (panizza, 2003): an environmental approach, a historical approach and a cultural approach (in a broad sense). these different procedures are strictly derived from the multidisciplinarity of the research; therefore they do not make up factors of discrimination or criticism, since the different points of view are directed to the pursuit of the same goal. fig. 1 the mont saint michel, in northern france, with the benedictine abbey architectonic complex. il mont saint michel, nella francia settentrionale, con il complesso architettonico dell’abbazia benedettina. 6 3.1 environmental approach the environmental approach is based on the relationships between the environment (in particular geomorphological) and archaeological, historical-architectural etc. assets, in conformity with a scheme in which the environment can be considered according to two points of view: on the one hand we have landscape resources (e.g. geomorphosites), and, on the other hand, geomorphological natural hazards (degradation, disarray etc.). in turn, cultural assets (in a strict sense) may be considered as both vulnerability (i.e. susceptible to material damage) and sites for fruition activities (e.g. tourism). these relationships may produce situations of either risk or impact (panizza, 1992a). an example of geomorphological risk is offered by the valley and adjacent hill of the temples of agrigento (cotecchia et al., 2000). the conservation of this site, which is a unique case of world relevance owing to its historical, archaeological, artistic and anthropological value, has been seriously threatened by both geomorphological disarray processes and man’s activity. in particular, the situation of the temples of juno lacinia and concordia, which are aligned along the southern edge of the hill, is very serious since the calcarenites making up the slope are affected by rock falls, topples and rotational slides, with involvement also of the underlying clay shales. examples of risk linked to chemical weathering are those resulting from sulphatization processes, which cause disaggregation of calcareous artefacts through the action of precipitation water made more aggressive by sulphur compounds produced by the combustion of coal. similar processes can occur on the basement of buildings where humidity is higher. in other cases hydrolysis processes may trigger differential erosion in buildings made up of materials with feldspar components and others constructed with more resistant types of materials. a well-known example of environmental risk and impact is offered by the situation of venice: recurrent “high water” has determined risk conditions whereas strong anthropic pressure has caused considerable degradation of the ecological, physical and biological standards of the lagoon environment. another example is mount sinai near the monastery of saint catherine (fig. 2), where there are ever increasing numbers of tourists, owing to the strong appeal of this site where, according to the old testament, moses received the tablets of the law from god. interest in this site is becoming more and more consistent also in relation to tourism infrastructures, which are expanding at a considerable rate near the seaside villages on the red sea, such as sharm el sheik. in this case, progressive remodelling and flattening of the slopes is taking place in order to create areas for building new hotels and related structures, with heavy consequences for environmental impact. 3.2 historical approach this approach is based on history considered as a factor of interpretation, that is on the concepts of continuity and integration between the present landscape and, going back in time, its history, prehistory and, finally, geohistory. for example, we may refer, on the one hand, to the relationships between social, strategic or religious needs and, on the other hand, to the geomorphological constraints of a particular site. our purpose is to analyse the landscape and recognise in it the integrations and relationships which have been established through time, by interpreting in an interdisciplinary manner all its “historical” components (in a broad sense) (panizza & piacente, 2000). examples can be as follows. a first explanatory case is offered by the balzi rossi (= red cliffs) (fig. 3), near ventimiglia (liguria): one can start from its geohistory (dolomite limestones from the upper jurassic, with tectonic joints), geomorphological genesis (sea cliff, karst modelling, littoral erosion and sedimentation, marine regressions and transgressions, reddish weathering of iron minerals, hence the name of “red cliffs” etc.), up to the arrival of man in the lower palaeolithic. in particular, the remains of the most ancient settlements were wiped out by the marine transgressions of the interglacial periods, which stretched as far as the caves, reworking prehistoric artefacts and deposing beach sediments, like those dating from the tyrrhenian (150,000-75,000 years bp). one of the most important discoveries consists of a three-fold burial from the upper palaeolithic (dated between 30,000 and 25,000 years bp). the latest “historical” evidence is given by the remains of military forts from the second world war and the inadequacy of the area for fruition by tourists. m. panizza & s. piacente fig. 2 example of environmental impact in the sinai, near the monastery of st. catherine. various parts of this territory appear remodelled and flattened for the construction of buildings and tourist infrastructures. esempio di impatto ambientale nel sinai, presso il monastero di santa caterina; vari settori del territorio appaiono rimodellati e spianati per la costruzione di edifici e infrastrutture turistiche. 7 another example is offered by the rocky cliff of vallerano in the province of viterbo (margottini, 2002), with a cave-dwelling containing frescoes depicting jesus christ as the saviour. this is a cliff made up of volcanic rocks from the vicus apparatus, dated between 200,000 and 150,000 years bp, in which a human dwelling of probable prehistoric origin was excavated. this site was subsequently remodelled and used by benedictine monks who turned it into a place of worship with rare frescoes, presumably ascribable to the ix-x century a.d. on the cave’s left-side wall the saviour is depicted, flanked by st. peter and an angel, whereas, on the bottom wall, a group of saints is shown. these frescoes, which stand out from a background adorned with multi-coloured frames, seem to be the work of an important byzantine artist. this cave was brought to light in the xix century, following a collapse that destroyed its outermost wall which was probably also frescoed. its rocky wall shows evident signs of geomorphological instability which point to progressive deterioration that could eventually lead to the disappearance of this settlement and the works of art housed in it. geomorphological investigations (margottini, 2002) have also identified several boundary conditions, mainly due to the penetration of tree roots into rock joints and consequent destabilisation, and water infiltration into the rock discontinuities and consequent slope failures. finally, conservation interventions should take into account possible aesthetic impacts on the site. 3.3 cultural approach (in a broad sense) this approach concerns the dialogue and cultural integration between humanistic and scientific disciplines. for example, one can refer to the relationships between construction, degradation and restoration of an architectonic site and the provenance, characteristics and deterioration proneness of the materials used for its construction, also in terms of culturally oriented upgrading policies. more in general, a response should be given to the ever-felt need for a “neo-humanistic” culture, that is for the unity of culture (panizza, 1989a). an example of this is offered by the investigations carried out on the paving of the historical centre of modena (comune – università di modena, 1999), which could be the starting point for a cultural, educational and tourist path. at first, the petrographic nature of the material (e.g., a marble slab or the use of cobbles from different rock types) is examined, by observing its mineralogical characteristics and going back to the area of provenance (for example: a quarry of “ammonitico rosso” in the verona hills for the marble slab; the geomorphological evolution for the cobblestones: from an apennine mountain down to the valley through erosion, fluvial transportation and sedimentation processes). subsequently, the methods of extraction and transport of the materials would be considered, as well as the epoch of these operations and the laying down of the paving. furthermore, the historical, social and cultural motivations for the choice of this type of material would be illustrated, as well as its state of conservation and the causes of possible disarray processes. regarding this, in a chapter of the previously quoted investigation (bertolani et al., 1999), it is pointed out that the state of conservation of the sidewalks in modena depends not only on the resistance of the material used or on the method used for its laying down but also on exceptional events. for example, in the last period of world war 2 street-paving in modena underwent very serious damage owing to the passage and parking of heavy military vehicles of the nazi forces. as regards modern paving interventions on some streets, where cobblestones are used, the construction of a central lane made of rock slabs or concrete would be advisable for the benefit of cyclists; this would in fact avoid unpleasant jerks or the improper use of sidewalks by cyclists (panizza, 2003). finally, we would like to quote the recovery for tourist-cultural purposes of a military fortress built by the soldiers of the italian alpine regiments during the first world war. this appraisal operation was carried out by the well-known mountain climber r. messner, who transformed this stronghold into a “museum amidst the clouds”, the highest in europe, located on mt. rite, at an altitude of 2100 m in the italian dolomites, between cortina d’ampezzo and pieve di cadore (fig. 4). here, reality and representation are intertwined. reality is embodied by the “pale mountains”, with their mythical names such as pelmo, civetta, marmolada, cristallo and tofane, which surround the fortress and break into the space of the museum through small wingeomorphosites: a bridge between ... fig. 3 balzi rossi (red cliffs), near ventimiglia, in the western ligurian coast: cave with prehistoric settlements corresponding to various palaeolithic levels. balzi rossi (red cliffs), vicino ventimiglia, nella riviera ligure di ponente: grotta con insediamenti preistorici di vari livelli del paleolitico. 8 dows. representation is given by the evocative collection of paintings of the dolomites, among which the watercolours of the english painter e.t. compton (1849-1921) stand out, together with many other objects and materials belonging to the history and myths of these mountains. the way to the fortress is an old military track readapted for the use of hikers and closed to motorised traffic, which starts from the xvi century village of cibiana, a small “jewel” of cadore, still showing its original plan and made cheerful by over fifty coloured, lively murals. 4. artistic suggestion there is no region, no place without natural features, among which the geomorphological aspects, in particular, make a landscape significant, unique for its landforms and the suggestions it conjures up. the features of the landscape are a sort of writing traced on the earth’s surface, an unpublished alphabet, used and reinterpreted by poets and artists who through their sensitivity can convey emotions to the onlookers. on the basis of these observations, a geologicalliterary itinerary was created starting from the assumption of the existence of specific emilia-romagna poetics and culture, linked to the outstanding morphological and geological features of our territory (bertacchini et al., 2002a). each geosite, with its description, has been combined with a literary passage by an author expressing atmospheres and identities of particular sites, further enhanced by the photographs of a great emilian master of the camera lens like franco fontana. this geological-literary itinerary was organised as a sort of guide for a sightseer yearning to meet nature also in its poetical forms by travelling in space and time. this can take place only through the awareness that nature can acquire a value for man only if the latter finds a way to go through the complete range of his/her senses, including those most specifically spiritual. at present, another research project is in progress: it consists of the study of some natural scenes from an artistic and geomorphological viewpoint, describing landscapes which. this approach aims to identify in the landscape the natural features which were painted in a picture. therefore, an art critic will carry out a detailed research on the painting whereas a geomorphologist will study and describe the landforms of the real landscape. it is by now evident that also science can offer itineraries of contemplation and aesthetic emotions which, although different, can be compared to those of the artists. the triggering of emotions comparable to the famous “stendhal’s syndrome” is not rare when particularly sensitive souls admire landscapes rich in specific suggestions. rañada (2003), in his recent book “the one thousand faces of science”, says: “nature shines with different lights and things sing in diverse ways many different songs. artists, poets and philosophers can perceive some of them, whereas scientists can perceive others”. references bertacchini m., giusti c., marchetti m., panizza m. & pellegrini m. 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(2002c) paesaggi culturali geologia e letteratura nel novecento in emilia romagna regione emilia romagna, servizio tutela del paesaggio, l’inchiostroblu ed. bologna, 137 pp. bertolani m., loschi ghittoni a.g. & guidetti violi l. (1999) pietre (più o meno) preziose dei marciam. panizza & s. piacente fig. 4 “museum amidst the clouds“, military fortress from world war 1, located on mt. rite, at an altitude of 2100 m in the eastern dolomites. “museo nelle nuvole“, fortezza militare della prima guerra mondiale, situato sul mt. rite, 2100 m, nelle dolomiti orientali. piedi modenesi in: comune e università di modena (eds), un tesoro di marciapiedi, nuovagrafica, carpi (mo). carton a., cavallin a., francavilla f., mantovani f., panizza m., pellegrini g.b. & tellini c. with the collaboration of bini a., castaldini d., giorgi g., floris b., marchetti m., soldati m. & surian n. 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(2003) i geomorfositi in un paesaggio culturale integrato in: s. piacente & g. poli (eds.), la memoria della terra, la terra della memoria. università degli studi di modena e reggio emilia regione emilia-romagna edizioni l'inchiostroblu, bologna, pp. 23-27. panizza m. & piacente s. (1991) relations between cultural resources and the natural environment in: n.s. baer, c. sabbioni & a.i. sors (eds.), proceedings of the european symposium: “ scince, technology and european cultural heritage”, bologna, 13-16 june 1989. butterworth-heinemann ltd., oxford, pp. 787793. panizza m. & piacente s. (1993) geomorphological assets evaluation z. geomorph. n. f., suppl. bd. 87, pp. 13-18. panizza m. & piacente s. (1999a) conoscenza geologica e gestione dei beni architettonici atti del convegno internazionale "archeologia e ambiente". ferrara, 3-4 aprile 1998. istituto per i beni artitstici, culturali, naturali della regione emilia romagna, a.b.a.c.o. edizioni, forlì, pp. 185-190. panizza m. & piacente s. (1999b) le forze della natura generatrici dei paesaggi e dell'aspetto del pianeta in: g. poli (ed.), geositi testimoni del tempo. regione emilia-romagna, bologna, pp. 28-29. panizza m. & piacente s. (1999c) il concetto di "bene" nel paesaggio fisico in: m. bertacchini, c. giusti, m. marchetti, m. panizza & m. pellegrini (eds.), i beni geologici della provincia di modena. artioli editore, modena, pp. 8. panizza m. & piacente s. (1999d) i beni di tipo geomorfologico in: m. bertacchini, c. giusti, m. marchetti, m. panizza & m. pellegrini (eds.), i beni geologici della provincia di modena. artioli editore, modena, pp. 21-45. panizza m. & piacente s. (2000) relazioni tra scienze della terra e patrimonio storico-archeologico in: g. lollino (ed.), condizionamenti geologici e geotecnici nella conservazione del patrimonio storico culturale. atti convegno geoben 2000, torino 7-9giugno 2000. pubbl. gndci n. 2133, pp. 723-730. panizza m. & piacente s. (2001) paesaggi in aula i.b.c., bologna, 9, 2, pp. 45-46. panizza, m. & piacente, s. (2003) geomorfologia culturale pitagora editrice, bologna, 350 pp. panizza m. & spampani m. (eds.) (1988) introduzione all’ambiente naturale e itinerario n. 1 passo giau mondeval croda da lago cortina. edizioni dolomiti, san vito di cadore belluno, 167 pp. panizza m., pellegrini m. & pozzi m. (1993) criteri geologici di costruzione della strada ducale estense da modena a massa del secolo xviii in: m. boriani e a. cazzani (eds.), le strade storiche un patrimonio da salvare, guerini e ass. ed., milano, pp. 79-84. piacente s. (1989) la conoscenza dell'ambiente per una sua tutela dinamica: due esempi nel9geomorphosites: a bridge between ... l'appennino modenese in: a. di blasi (ed.), l'italia che cambia. il contributo della geografia, vol. ii, pp. 499-504. piacente s. (1999a) sensibilità geologica e consenso sociale mem. descr. carta geol. d’it. 54, pp. 451-454. piacente s. (1999b) la conoscenza scientifica, un valore aggiunto in: g. poli (ed.), geositi testimoni del tempo, regione emilia romagna, pp. 234-244. piacente s. (2003) la memoria della terra, la terra della memoria in s. piacente & g. poli (eds), la memoria della terra, la terra della memoria, l’inchiostroblu, bologna, pp. 15-24. piacente s. & soldati m. (1989) i mulini dell'alta valle del panaro: un'occasione di analisi integrata per la conoscenza dell'appennino modenese prov. di modena, provv. agli studi e italia nostra, 131 pp. piacente s. & giusti c. (2000) geotopos, una oportunidad para la difusion y valoracion de la cultura geologica regional in: f.j. barba regidor & j. saiz de omeñaca gonzález (eds.), documentos del xi simposio sobre la enseñanza de la geología, 11-15 september 2000, universidad de cantabria, santander, pp. 134-137. piacente s. & poli g. (2003) la memoria della terra, la terra della memoria l’inchiostroblu, bologna, 159 pp. piacente s., bertacchini m. & coratza p. (2001) la cartografia come strumento di percezione e di gestione dinamica dei beni geologici in: g. scanu (ed.), cultura cartografica e culture del territorio atti del convegno nazionale (sassari 12-13 dicembre 2000) , bollettino della associazione italiana di cartografia, 111-112-113, pp. 401-407. piacente s., bertacchini m. & coratza p. (2003) geomorphological tourism amidst nature and culture: examples from emilia-romagna (italy) in: e. reynard, c. holzmann, d. guex & n. summermatter (eds.), géomorphologie et tourisme, actes de la réunion annuelle de la société suisse de géomorphologie (ssgm), finhaut, 21-23 septembre 2001, institut de géographie de l'université de lausanne (igul), pp. 145-155. rañada a. f. (2003) i mille volti della scienza. cultura scientifica e umanistica nella società contemporanea edizioni dedalo, 224 pp. secchi b. (2001) la città contemporanea e il suo progetto convegno "lezioni di storia urbana", assessorato alla cultura, comune di modena, nov.-dic. 2001, modena, pp. 13-17. 10 m. panizza & s. piacente imp.04santo nuove ipotesi sulla formazione dei piping sinkhole in aree alluvionali: il caso della piana di forino (avellino, campania) del prete s.*, giulivo i.**, santo a.*** * federazione speleologica campana **geologo dirigente ufficio difesa suolo regione campania ***dipartimento di ingegneria idraulica, geotecnica ed ambientale università di napoli “federico ii”, santo@unina.it riassunto: s. del prete et al., nuove ipotesi sulla formazione dei piping sinkhole in aree alluvionali: il caso della piana di forino (avellino, campania) (it issn 0394-3356, 2008). vengono esposti i risultati di uno studio eseguito nel bacino endoreico di forino (av) e proposta una nuova ipotesi sulla genesi di piping sinkhole in aree alluvionali. lo studio si è avvalso di indagini in sito che hanno permesso di ricostruire la stratigrafia di sottosuolo (primi 50 metri di profondità), caratterizzata dalla presenza di un riempimento alluvionale di natura limoso-sabbiosa, poggiante su di un substrato poco permeabile (ignimbrite campana e flysch miocenici). è stata quindi esclusa la presenza di calcari e di vuoti carsici per almeno i primi 50 m di profondità. nell’area sono stati censiti 8 sinkhole, alcuni recenti, altri più antichi e ormai completamente riempiti da materiale di riporto. le perforazioni effettuate in alcuni di essi e l’osservazione diretta dello sprofondamento più recente (12 giugno 2005), hanno evidenziato che i vuoti si sono formati a partire da circa 25 m di profondità e che hanno interessato i terreni sabbioso-limosi alluvionali. i sinkhole si allineano lungo la direzione di drenaggio preferenziale della falda presente nel corpo alluvionale e sono concentrati alla base del versante settentrionale di m. romola che costituisce, quindi, il settore della piana più suscettibile a questi fenomeni. lo studio ha dimostrato che i vuoti si generano per fenomeni di erosione causati da una circolazione idrica sotterranea, attiva in concomitanza di periodi molto piovosi e caratterizzata, probabilmente, da moti turbolenti. tale circolazione si instaura al contatto tra il materiale sabbioso-limoso ed i sottostanti strati poco permeabili (ignimbrite campana e flysch miocenici). è molto probabile che la circolazione idrica sotterranea sia alimentata anche da falde sospese ed in rete carsica presenti nei massicci carbonatici che circondano la piana. per quanto riguarda l’erosione dei notevoli volumi asportati (alcune migliaia di m3) è ipotizzabile che essi siano smaltiti da inghiottitoi sepolti, presenti lungo il margine orientale della conca endoreica. i risultati di questo studio rappresentano un primo importante contributo per successive ricerche mirate all’identificazione di altri vuoti sotterranei che potrebbero essere molto prossimi alla superficie topografica e creare, quindi, situazioni di alto rischio. abstract: s. del prete et al., new genetic hypothesis about piping sinkhole formation in alluvial plain: the case study of forino (avellino, campania) (it issn 0394-3356, 2008). this paper deals with sinkholes phenomena occurred in the intramontane basin of forino village (campania, southern italy). a new genetic hypothesis about piping sinkhole formation in alluvial plain is proposed. aiming at the definition of the underground stratigraphy, some boreholes have been drilled down to the depth of 50 meters. they showed the presence of an alluvial silty and sandy body laying on a impermeable substratum made up of tuff (campanian ignimbrite) and miocene flysch deposits. therefore, in the first 50 m of the depth, the presence of calcareous bedrock and caves can be certainly excluded. eight sinkholes have been observed in the area; some of them are recent, other are older and completely filled in with reworked material. some of the boreholes were carried out inside and around the more recent sinkhole (12 june 2005) and they showed it had started forming at about 25 m of depth, affecting sandy and silty alluvial deposits. the studied sinkholes are lined up with the flow direction of the groundwater located within the alluvial body at the base of the northern slope of m. romola. the last one is the sector more susceptible for this phenomena. the collected data suggest that the sinkholes developed because the underground water circulation, probably with turbulent regime, produced erosion phenomena in the sandy-silty alluvial deposits, causing void formation. this circulation is only active during rainy day periods and is located at the contact between the impermeable substratum (top of campanian ignimbrite end miocenic flysch) and the sandy and silty alluvial deposits. probably this water table is also fed laterally by groundwater coming from the carbonate massifs surrounding the plain. as far as the problem of volumes removed (some thousands of m3) is concerned, the presence of buried ponors, along the eastern edge of the endoreic basin, which can transfer in depth the sandy materials, is hypothesised. the results of this study represents a first step for new researches aimed at recognizing the presence of other underground voids that could be very near to the topographic surface producing high risk situations. parole chiave: sinkhole, suffosione profonda, polje, campania, appennino meridionale. key words: sinkhole, deep piping, polje, campania region, southern apennines il quaternario italian journal of quaternary sciences 21(2), 2008 395-408 1. premessa a livello mondiale è ormai acquisito che il verificarsi di un improvviso sprofondamento (sinkhole) costituisce un grave problema nella gestione delle infrastrutture presenti sul territorio soprattutto a causa della difficile localizzazione e previsione spazio-temporale del fenomeno. recentemente anche in italia la comunità scientifica ha dedicato particolare attenzione allo studio dei sinkhole, soprattutto dopo alcuni casi che hanno interessato centri abitati; le prime sintesi sono state pubblicate negli atti di alcuni convegni, dedicati a questa tematica (aa.vv., 2000; 2004). i sinkhole di origine naturale si originano in contesti geologici ed idrogeologici piuttosto complessi; essi si aprono sia in piane alluvionali (cover collapse sinkhole, deep piping sinkhole, subsidence sinkhole) che su massicci carsici (cover sinkhole, collapse sinkhole, solu396 s. del prete, i. giulivo & a. santo tion sinkhole, subsidence sinkhole). generalmente la loro genesi è legata alla presenza di alcuni fattori predisponenti quali: substrato carsificabile, copertura clastica a granulometria variabile, circolazione idrica sotterranea con falde in pressione, presenza di fluidi mineralizzati, presenza di lineamenti tettonici attivi ed eventi sismici che possono concorrere con vario grado di causalità (sinclair & stewart, 1985; facenna et al., 1993; berti et al., 2000; capelli et al., 2000; 2004; ciotoli et al., 2001; nisio, 2003; closson, 2004; gutiérrez, 2004; ferrelli et al., 2004; nisio et al., 2004; nisio & scapola, 2005; waltham et al., 2005). in campania sono stati circa 100 sinkhole (del prete et al., 2004) che interessano diversi contesti geomorfologici e che coinvolgono differenti litologie (fig. 1). è stato osservato che i meccanismi d’innesco possono essere molto diversi a seconda dei casi (del prete et al., 2004; del prete & santo, 2005; cozzolino et al., 2007; santo et al. 2007) e non ancora del tutto chiari soprattutto per quei fenomeni che interessano le aree alluvionali. in questa nota vengono descritti alcuni fenomeni di piping sinkhole recentemente verificatisi nel bacino alluvionale di forino (av). a seguito di alcuni sopralluoghi e di dati forniti dal comune, si è potuto accertare che l’area è stata interessata più volte in passato da improvvisi sprofondamenti. visto il crescente sviluppo urbano del centro abitato nella piana e grazie anche ad un finanziamento dell’ufficio difesa suolo della regione campania, è stato predisposto un primo programma di fig. 1 schema geologico della campania con l’ubicazione delle aree interessate dalla presenza di sinkhole. legenda: 1) depositi delle piane costiere e delle conche intramontane; rocce vulcaniche s.l. (quaternario); 2) depositi terrigeni (mesozoico-terziario); 3) rocce carbonatiche (mesozoico-terziario); 4) sinkhole su versanti carbonatici; 5) sinkhole in aree di piana alluvionale. il riquadro indica l’area di studio. geological sketch map of campania and location of sinkhole: 1) coastal plain and endoreic basins deposits; volcanic rocks s.l. (quaternary); 2) flysch deposits (mesozoic-tertiary); 3) deposits of carbonatic platform (mesozoic-tertiary); 4) sinkhole along carbonate slope; 5) sinkhole in alluvial plain. the square is refer to the area of study. indagini finalizzato alla comprensione della genesi dei sinkhole. le prime indagini in sito hanno permesso di giungere ad interessanti considerazioni sulla loro possibile genesi. 2. inquadramento geologico-geomorfologico ed idrogeologia della conca di forino la conca di forino costituisce un bacino endoreico di circa 10 km2 ed altitudine media di 400 m s.l.m. localizzato pochi km a sud della città di avellino tra i 397nuove ipotesi sulla formazione ... rilievi carbonatici di pizzo d’alvano, e dei m.ti picentini (fig. 2). la genesi della depressione è associata all’azione di faglie attive durante il plio-quaternario che hanno dislocato le dorsali calcareo mesozoiche su cui poggiano, in trasgressione, successioni terrigene mioceniche. nel centro della piana, il substrato miocenico ed i sottostanti calcari risultano ribassati a gradinata sino ad un massimo di poche centinaia di metri (fig. 3). il riempimento quaternario è costituito da potenti successioni fluvio-lacustri, per lo più di natura limo-argillosa, che sono ricoperte da tufi dell’ignimbrite campana (39.000 fig. 2 schema geologico della piana di forino. legenda: 1) depositi piroclastici rimaneggiati e depositi alluvionali (pleistocene sup.olocene); 2) detrito di versante (pleistocene sup.-olocene); 3) depositi in facies di flysch (miocene); 4) calcari mesozoici; 5) faglia; 6) sorgente; 7) conoide alluvionale; 8) inghiottitoio; 9) sinkhole; 10) traccia di sezione di fig. 3. geological map of the forino plain. legend: 1) pyroclastic and alluvial deposits (upper pleistocene-holocene); 2) detritical talus (upper pleistocene-holocene); 3) miocenic flysch; 4) mesozoic limestones; 5) fault; 6) spring; 7) alluvial fan; 8) ponor; 9) sinkhole; 10) geological cross section of fig. 3. anni; de vivo et al., 2001) e poi da alternanze di limi e sabbie legate a piroclastiti rimaneggiate. gli ultimi 15÷20 m del riempimento della piana sono costituiti da una maggiore presenza di depositi piroclastici da caduta provenienti dal vicino distretto vulcanico del sommavesuvio. l’assetto geomorfologico è quello tipico dei bacini endoreici nei quali le acque di ruscellamento superficiale creano frequentemente fenomeni di trasporto solido e alluvionamento favoriti anche dalla notevole estensione di depositi piroclastici sui versanti. in particolare, nel settore meridionale, alla base dei versanti del monte romola e del monte piesco, aste a regime torrentizio alimentano diversi corpi di conoide (fig. 2). le acque di ruscellamento superficiale una volta raggiunta la piana, sono in gran parte incanalate verso l’inghiottitoio di celzi (fig. 2), tuttavia, in concomitanza di intensi eventi meteorici, l’inghiottitoio non riesce a smaltire la totalità delle acque provocando ripetuti fenomeni di ristagno che coinvolgono anche il centro urbano. per quanto riguarda l’assetto idrogeologico, la piana di forino rientra nella più ampia idrostruttura dell’unità dei monti di avella e partenio, a nord, e di quella del pizzone-alvano, a sud (civita et al., 1970; celico, 1979) la cui falda di base drena preferenzialmente verso sw in direzione degli importanti gruppi sorgivi di sarno e nocera. santo et al., 1998, attraverso il censimento dei pozzi per uso irriguo e con profondità variabile dai 20 ai 50 m, hanno rilevato la presenza di una falda alta in quota localizzata nel riempimento alluvionale della piana con deflusso preferenziale orientato da wnw verso ene (fig. 4). la falda si localizza a circa 370 m s.l.m e cioè circa 30 sotto il piano campagna. il disegno piezometrico evidenzia un’alimentazione dai vicini massicci carbonatici ed in particolare da quelli localizzati a nw e, subordinatamente, da quelli presenti a sw della piana (santo et al., 1998). più in profondità, ad una quota di circa 250 m s.l.m., è presente la falda di base dei calcari il cui recapito è rappresentato dal gruppo sorgivo laura e labso (celico, 1979). la conca di forino, quindi, è caratterizzata dalla presenza di due falde la più alta delle quali si localizza nel corpo alluvionale sabbioso limoso ed è alimentata per travaso dai calcari; la più profonda si imposta nei calcari mesozoici e sarebbe separata dalla prima per l’interposizione di materiali lacustri e dei flysch miocenici. 3. i sinkhole della piana di forino il 12 giugno del 2005 alle ore 18.30 in contrada petrosa (località celzi) nel comune di forino (avellino) si è aperta improvvisamente una voragine a pochi metri da una strada comunale e da alcune abitazioni rurali. lo sprofondamento ha coinvolto terreni prevalentemente di natura limoso-sabbiosa ed ha inghiottito alcuni alberi di nocciolo; al momento della formazione aveva un diametro di circa 12 m e profondità di circa 25 m (fig. 5). la zona è stata subito recintata ma nei mesi successivi, a causa di franamenti periodici del ciglio, la voragine si è ampliata fino a raggiungere un diametro di 25 m ed una profondità di circa 12 m nel marzo del 2007 (fig. 6). il primo passo dello studio è stato quello di effettuare un accurato censimento dei sinkhole presenti nella piana; ciò è stato possibile attraverso testimonianze locali ed un’attenta analisi delle morfologie del terreno e della cartografia storica. nonostante molti di essi siano stati ricolmati ed obliterati, ne sono stati censiti con certezza 8 (fig. 2), due dei quali si sono verificati 398 fig. 3 sezioni geologiche del bacino di forino. 1) depositi piroclastici rimaneggiati e depositi alluvionali (pleistocene sup.-olocene); 2) detrito di versante (pleistocene sup.-olocene); 3) depositi in facies di flysch (miocene); 4) calcari mesozoici; 5) faglia; 6) sondaggi (da santo et al., 1998 mod.). cross section of the forino plain. legend: 1) reworked pyroclastic and alluvial deposits (upper pleistocene-holocene); 2) detritical talus (upper pleistocene-holocene); 3) miocenic flysch; 4) mesozoic limestones; 5) fault; 6) borehole (from santo et al., 1998, mod). s. del prete, i. giulivo & a. santo particolarmente interessante sono le evidenze del sinkhole sk5 ubicato nell’estremo settore sud orientale della conca di forino (fig. 7). sul suo fondo sono state osservate chiare evidenze di riattivazioni recenti per la presenza di radici tranciate dai movimenti di subsidenza e, lungo i suoi bordi, sono evidenti fratture concentriche con piccole scarpate che, per richiamo verso il centro, individuano più ordini di superfici terrazzate associate all’ampliamento del sinkhole. per alcuni sinkhole la memoria storica è ancora 399 fig. 4 isopiezometriche della falda della piana di forino (da santo et al, 1998 mod.). legenda: 1) curva isopiezometrica e relativa quota s.l.m.; 2) sinkhole; 3) inghiottitoio; 4) sorgente; 5) direzione di drenaggio sotterraneo; 6) sondaggio; 7) flysch miocenici; 8) calcari mesozoici. isopiezometric curves of the forino plain (from santo et al., 1998, mod.). legend: 1) isopiezometric curve and altitude above sea-level; 2) sinkhole; 3) ponor; 4) spring; 5) groundwater flow direction; 6) borehole; 7) miocene flysch; 8) mesozoic limestones. fig. 5 il sinkhole di contrada petrosa pochi giorni dopo la sua formazione (25 giugno 2005; diametro circa 12m e profondità di circa 25m). the contrada petrosa sinkhole few days later its formation (2005, june 25; diameter 12m; depth 25mt). nel marzo e nel giugno 2005. i sinkhole sono ubicati tutti alle falde del rilievo di m. romola (fig. 2) e di questi 5 sono ancora ben preservati, mentre gli altri 3 sono appena accennati da blande concavità del terreno. tra i sinkhole riportati in fig. 2, quelli codificati con la sigla sk3, sk4 e sk5 si presentano come depressioni circolari del diametro di 20÷30 m talora bordate da pareti subverticali ancora ben preservate alte fino a 3÷4 m. nuove ipotesi sulla formazione ... viva nella popolazione più anziana, come dimostra l’attribuzione di toponimi come nel caso della “fossa donna teresa” (cfr sk3 in fig. 2) che è ubicata al margine di un conoide alluvionale. secondo alcune fonti locali la sua formazione risalirebbe ad almeno 80 anni fa e sul suo fondo si tramanda della presenza di un piccolo stagno ove i locali si recavano a fare il bagno. poche centinaia di metri a nord di questo sinkhole, sono presenti alcune (almeno 3) blande depressioni chiuse. le fonti locali, tuttavia, tramandano a memoria d’uomo, solo di un fenomeno in località “fossa di zarra” (sk2 in fig. 2). nella stessa zona, tuttavia, testimonianze locali riportano che durante una trivellazione per ricerca d’acqua alcune aste sono sprofondate e andate perse per il rinvenimento di un vuoto associato ad una cavità. anche in corrispondenza del sinkhole sk1 è ancora riconoscibile una blanda depressione circolare chiusa nel terreno che, secondo fonti locali, sarebbe da riferire al “relitto” di un fenomeno di sprofondamento risalente ad oltre 80 anni fa. gli eventi recenti, infine, sono quelli che riguardano il sinkhole sk6, risalente al marzo 2005, e l’sk7 del giugno 2005 in contrada petrosa. il primo si presenta come una forma avente un diametro di circa 15 m ed una profondità di circa 3 m (fig. 8). lungo il bordo sono presenti fratture concentriche, mentre il fondo si presenta molto irregolare con 400 fig. 6 panoramica della stratigrafia visibile lungo le pareti del sinkhole di contrada petrosa (foto del marzo 2007). legenda: a) suoli recenti con due livelli di eruzioni vulcaniche storiche (472d.c. e 1631); b) pomici dell’eruzione vulcanica di mercato/ottaviano, 8000 anni fa; c) cineriti rimaneggiate (limi sabbiosi) con pomici e locali livelli di sabbie e paleosuoli; d) pomici grigie e scorie probabilmente riferibili all’eruzione di agnano rimaneggiate in ambiente alluvionale; e) cineriti (limi sabbiosi) pedogenizzate con locali livelli di sabbie fini. view of stratigraphy along the wall of contrada petrosa sinkhole (photo of 2007, march). legend: a) present soils with two levels of recent tephra (472 d.c. and 1631 eruptions); b) tephra of mercato/ottaviano eruption (8000 y. b.p); ash and pumice interbedded with sands and paleosoil levels; d) grey pumices and scoria of agnano eruption reworked in alluvial environment; e) weathered ash levels with thin sandy layers. fig. 7 panoramica del sinkhole sk5 ubicato sullo stralcio di fig. 2. sono ben evidenti (linea a punti) più ordini di superfici di collasso. view of sinkhole sk5 (cfr. fig. 2). it is evident the presence (white dot line) of different collapse surfaces. s. del prete, i. giulivo & a. santo alberi sradicati. il fenomeno più recente, invece, si è verificato intorno alle 18.30 del 12 giugno 2005. esso presentava un diametro circolare iniziale di 12 m ed una profondità di almeno 25 m per un volume complessivo di circa 2500 m3 (fig. 5). è da segnalare che al momento dello sprofondamento non si sono avute risalite di acqua, sebbene alcuni testimoni locali, hanno dichiarato di aver sentito passaggio di acqua in profondità. 4. piano di indagini e stratigrafia dei sinkhole per poter comprendere l’assetto geologico stratigrafico di dettaglio dei terreni nel quale si è generato lo sprofondamento di contrada petrosa (cfr. sk7), sono state eseguite alcune perforazioni a carotaggio continuo, tutte condizionate a piezometro, al fine di poter monitorare le oscillazioni della falda. in un primo momento sono stati eseguiti 4 sondaggi lungo il perimetro dello sprofondamento del giugno 2005 (sondaggi s1, s2, s3, s4 in fig. 9); successivamente, dopo aver riempito il sinkhole con terreno vegetale esso è stato riperforato nel suo centro (sondaggio s7 in fig. 9). altri 2 sondaggi sono stati eseguiti all’interno dei sinkhole sk2 e sk3 che risultano ormai quasi completamente interrati. di seguito sono riportate le stratigrafie dei sondaggi eseguiti: il sondaggio s1 è stato eseguito 22 m a ne del sinkhole di contrada petrosa ed ha raggiunto una profondità di 38 m. a partire dal piano campagna è stato incontrato uno spessore di circa 10 m di depositi piroclastici da caduta ascrivibili ad eruzioni del somma vesuvio (eruzioni di mercato risalente a 8000 anni fa, rolandi et al., 1993, probabilmente di agnano risalente a 10.550 anni fa; di vito et al., 1999) in alternanza con livelli cineritici pedogenizzati, livelli sabbiosi e paleosuoli che poggiano su circa 12 m di alternanze di piroclastiti rimaneggiate in ambiente alluvionale e di fall pomiceocineritici ascrivibili, probabilmente, alle eruzioni di sarno (17.000 anni fa; rolandi, 1997). nella parte bassa di questo intervallo, tra i 19 e 22 m, sono presenti sabbie alluvionali fini. la prima decina di metri della stratigrafia appena descritta ha trovato anche riscontro con quella affiorante lungo le pareti del sinkhole sk7 (fig. 6). un paleosuolo divide nettamente i depositi alluvionali dalla sottostante ignimbrite campana (39.000 anni) che è stata carotata per uno spessore di circa 10m e si presenta lapideo di colore giallo. il tufo, infine, poggia su flysch arenacei del substrato miocenico. il sondaggio s2 è stato eseguito circa 25 m a sw rispetto al centro dello sprofondamento di contrada petrosa ed ha una raggiunto una profondità di 52 m. in sintesi la perforazione ha incontrato per i primi 6 m livelli vulcanici cineritici, spesso pedogenizzati ed alternati a livelli pomicei rimaneggiati; a seguire, sino a circa 23 m di profondità, sono state incontrate prevalentemente sabbie e limi sabbiosi di natura piroclastica ma spesso rimaneggiati in ambiente alluvionale. da 23 m sino a circa 40 m si ritrovano depositi cineritici e tufacei dell’ignimbrite campana che poggiano sul substrato arenaceo, carotato per 12 m sino alla profondità di 52 m dal piano campagna. il sondaggio s3 è ubicato circa 50 m a sud dello sprofondamento di contrada petrosa e si è spinto fino alla profondità di 30 m. per i primi 18 m sono state incontrate alternanze 401 fig. 8 il sinkhole sk6 ( marzo 2005) dopo due anni (marzo2007). view of 2005 march sinkhole sk6 two years later (march 2007). nuove ipotesi sulla formazione ... di cineriti pedogenizzate, livelli pomicei e livelli sabbiosi, per lo più riferibili al rimaneggiamento di fall pomicei in ambiente di conoide alluvionale. da 18 m a 21 m sono stati carotati i depositi cineritici e tufacei dell’ignimbrite campana ed, infine, sino a 30 m il substrato flyschoide in facies arenacea. il sondaggio s4 è localizzato circa 35 m a nord dello sprofondamento di contrada petrosa ed ha raggiunto la profondità di 25 m. per i primi 24 m sono state incontrate alternanze di cineriti pomicee, sabbie e sabbie limose, talora legate a prodotti da caduta in posto, e talora rimaneggiate in ambiente alluvionale. tra 24 m e 25 m di profondità è stata rilevata una cinerite in posto contenente molte pomici idiomorfe molto probabilmente da correlare alla parte alta dell’ignimbrite campana. il sondaggio s5 è stato realizzato nella zona centrale del sinkhole sk3 (cfr. fig. 2) ubicato a circa 500 m ad ovest dallo sprofondamento di contrada petrosa ed ha raggiunto i 30 m di profondità. dal piano campagna sino a circa 21 m di profondità sono stati riscontrati terreni di riempimento del sinkhole di natura limoso-argillosa privi di strutture sedimentarie e ricchi in frustoli carboniosi. da 21 m sino a 30 m sono state riscontrate prevalentemente sabbie piroclastiche rimaneggiate in ambiente di conoide alluvionale. il sondaggio s6 è stato effettuato al centro del sinkhole sk2 (cfr. fig. 2) ubicato circa 600 m ad ovest dello sprofondamento di contrada petrosa, ed anch’esso è stato spinto fino a 30 m di profondità. sino a 20 m di profondità sono stati rinvenuti terreni di riporto privi di strutture sedimentarie spesso con notevole presenza di sostanza organica. da 20 a 30 m sono stati riscontrati terreni in posto prevalentemente sabbiosi e limoso-sabbiosi legati a depositi piroclastici rimaneggiati in ambiente alluvionale. il sondaggio s7 è stato eseguito al centro dello sprofondamento di contrada petrosa fino ad una profondità di 51 m dopo aver completamente riempito il sinkhole con circa 3000 m3 di terreno vegetale prelevato da altri scavi realizzati nella piana di forino. il sondaggio, per i primi 15 m eseguito a distruzione, dai 15 a 25 m ha incontrato alternanze di sabbie piroclastiche rimaneggiate crollate dalle pareti del sinkhole. tra 25 e 27 m è stato ritrovato un livello più ricco in sostanza organica nel quale è stato carotato un tronco di nocciolo non carbonizzato a nostro avviso sicuramente legato allo sprofondamento del giugno 2005. fig. 9 dettaglio topografico dell’area di contrada petrosa con l’ubicazione dei sinkhole sk1, sk4, sk7, sk8 e delle perforazioni (s1, s2; s3, s4, s7) . contrada petrosa topographic map with sinkhole (sk1; sk4; sk7 sk8) and borehole (s1, s2; s3, s4 e s7) locations. 402 s. del prete, i. giulivo & a. santo seguono sino a circa 28,50 altri intervalli cineritici pedogenizzati molto probabilmente ancora legati allo sprofondamento del 12 giugno. da 28,50 m a 33 m sono state incontrate sabbie e limi sabbiosi in posto di ambiente alluvionale. da 33 a 50 m è stata perforata l’ignimbrite campana che poggia direttamente sul substrato in facies di flysch carotato per circa 1 m. 5. interpretazione dei dati e ipotesi genetiche dei sinkhole i sondaggi effettuati sui 4 lati dello sprofondamento di contrada petrosa (s1, s2, s3, s4) e quello al centro del sinkhole (s7) insieme ai dati derivanti dalle due perforazioni eseguite in due sinkhole antichi (s5, s6), permettono di proporre un primo chiaro modello stratigrafico del settore del territorio di forino interessato dagli sprofondamenti e di avanzare alcune preliminari considerazioni sulla loro genesi. in tutti i sondaggi è stata osservata la presenza per i primi metri di depositi vulcanoclastici da caduta di natura sabbioso-limosa che passano in profondità, sino a circa 25m, a sabbie e limi di ambiente alluvionale. nei sondaggi eseguiti in vicinanza dello sprofondamento della petrosa (fig. 10) è stata intercettata l’importante eruzione vulcanica dell’ignimbrite campana che si presenta con cineriti e tufi lapidei prevalentemente nella facies gialla con spessore variabile da pochi metri a circa 17 m. in 4 di questi sondaggi è stato intercettato anche il substrato pre-quaternario rappresentato da depositi miocenici di natura arenacea. nessuna delle perforazioni, inoltre, ha intercettato il substrato calcareo. nei due sondaggi eseguiti nei sinkhole antichi di zarra e donna teresa (s6 ed s5; cfr. figg. 2 e 4), sono stati rinvenuti 20 m di terreni di riporto, che poggiano su sabbie e limi alluvionali in posto. i dati stratigrafici ci permettono quindi di escludere la presenza di un vuoto carsico almeno per i primi 52 m di profondità. sembrerebbe che i vuoti ipogei necessari per giustificare le volumetrie delle voragini, si siano formati nei sedimenti sabbioso-limosi posti al top dell’ignimbrite campana come testimoniato anche dal ritrovamento di un tronco di nocciolo durante la perforazione del sondaggio s7 riscontrato a 26 m di profondità e pochi metri al disopra del substrato in posto. le sezioni geologiche realizzate nell’area di contrada petrosa (fig. 10), permettono di ricostruire la successione degli eventi sedimentari; esse infatti evidenziano chiaramente (figg. 10 e 11) un substrato artifig. 10 ricostruzione stratigrafica del sito del sinkhole sk7 in contrada petrosa. 1) materiale di riempimento del sinkhole; 2) materiale da crollo del sinkhole; 3) alternanza di livelli cineritico-pomicei rimaneggiati e livelli pomiceo-scoriacei da caduta; 4) piroclastiti sabbioso limose rimaneggiate, alternate a livelli cineritico pomicei pedogenizzati; 5) cappellaccio dell’ignimbrite campana; 6) ignimbrite campana; 7) flysch miocenici. stratigraphic cross section of sk7 sinkhole at contrada petrosa site. 1) sinkhole artificial filling deposits; 2) rock fall deposits; 3) reworked ash and pumice levels alternated with fall deposits; 4) reworked sandy and silty pyroclastic deposits alternated with pumice and ash levels; 5) cap rock of campanian ignimbrite; 6) campanian ignimbrite; 7) miocenic flysch. 403nuove ipotesi sulla formazione ... fig. 11 evoluzione geomorfologica del sinkhole sk7 di contrada petrosa. a) paleoincisione nel substrato terrigeno (circa 40.000 anni fa); b) deposizione dell’ignimbrite campana (circa 39.000 anni fa); c) erosione dell’ignimbrite campana operata dal nuovo reticolo idrografico (circa 20.000 anni fa); d)fase di riempimento della paleoincisione (tra 20.000 e 10.000 anni fa circa); e) ulteriore fase di aggradazione della piana per caduta di depositi piroclastici che seppellisce definitivamente la paleo-valle. in profondità si creano le condizioni per la circolazione idrica nell’acquifero piroclastico-alluvionale con un deflusso preferenziale che segue la paleoincisione sepolta (post 10.000 anni fa); f) la circolazione idrica sotterranea innesca un lento processo di erosione sotterranea che porta alla formazione di vuoti; g) la lenta evoluzione del vuoto verso l’alto (h) origina un sinkhole. geomorphological evolution of contrada petrosa sinkhole (sk7). a) paleo-gully on flysch bedrock (about 40.000 y. b.p.); b) deposition of the campanian ignimbrite (about 39.000 y. b.p.); c) erosion of the campanian ignimbrite and genesis of a new gully (about 20.000 y. b.p.); d) phase of valley filling (between 20.000 and 10.000 y. b.p.); e) plain aggradation by means of pyroclastic fall deposits. the ancient valley, cut in the campanian ignimbrite formation and filled in with reworked pyroclastic deposits, is now definitely buried (post 10.000 y.b.p.); f) groundwater circulation inside the alluvial-pyroclastic aquifer has a flow direction oriented like the buried paleo-gully and causes a slow erosion (suffosion) producing void formations; g) the upward void migration (h) causes the sinkhole. 404 s. del prete, i. giulivo & a. santo colato e caratterizzato dalla presenza di una paleoincisione sepolta impostata nel substrato miocenico (fig. 11a). questa vallecola sarebbe stata ricolmata durante la deposizione dell’ignimbrite campana (circa 39.000 anni fa; fig. 11b) e nuovamente reincisa dai successivi fenomeni di erosione lineare (fig. 11c). questo dato trova conferma nell’assenza, nel sondaggio s7, dei livelli più alti dell’ignimbrite campana (cappellaccio) presente invece nei settori laterali (sondaggi s1, s2, s3 e s4; cfr. fig. 10). tra 20.000 e 10.000 anni fa si verifica una prima fase di riempimento della paleoincisione per l’apporto di depositi alluvionali nella piana costituiti da piroclastiti rimaneggiate di natura sabbioso-limosa e dilavate dai versanti (eruzione di “sarno”; fig. 11d). più recentemente, negli ultimi 10.000 anni, si hanno altri apporti di materiali piroclastici, talora in giacitura primaria, di origine flegreo-vesuviana (eruzioni di “ottaviano-mercato” e di “avellino”) alternati a paleosuoli e a livelli alluvionali limoso-sabbiosi (fig. 11e). contemporaneamente al riempimento della piana, si instaurarono le condizioni per la formazione di una falda superficiale nell’acquifero piroclastico alluvionale alimentata anche da travasi laterali provenienti dai vicini massicci carbonatici. questa circolazione idrica sotterranea trova nelle paleoincisioni sepolte e colmate da corpi sabbiosi, delle vie preferenziali di deflusso. essa è particolarmente attiva in concomitanza di inverni molto piovosi, e si instaura nel riempimento alluvionale al contatto con substrato impermeabile (ignimbrite campana e flysch miocenici. la direzione di drenaggio è orientata parallelamente al versante di m. romola da wnw verso ese come evidenziato in santo et al., 1998 (cfr. fig. 4). è probabile che in queste condizioni, analogamente a quanto riportato in letteratura per altri contesti (arkin & gilat, 2000), il notevole carico idraulico della falda collegato ad inverni molto piovosi possa creare locali situazioni di erosione sotterranea (soffusione profonda) nei livelli limoso-sabbiosi (fig. 11f e 11g). non è un caso che i sinkhole censiti si allineano nella direzione di drenaggio preferenziale della falda. a tale proposito durante la campagna di indagini tutte le perforazioni sono state condizionate con piezometro a tubo aperto per la misurazione della falda. le misure eseguite dal maggio 2007 a giugno 2008 non hanno rilevato la presenza della falda nel corpo alluvionale e nel substrato. la presenza di acqua talora rilevata ai piezometri è da imputare a ristagni a fondo foro come evidenziato anche dall’assenza di variazioni significative del livello idrico. va ricordato comunque che l’anno 2007 è stato particolarmente siccitoso mentre il livello della falda doveva essere sicuramente più alto nell’inverno 20042005 quando cioè si sono avuti gli sprofondamenti. a tal proposito, in fig. 12 si riportano le piogge cumulate del periodo della ricarica dell’inverno 20042005. si può notare come questo periodo risulta eccezionalmente piovoso se confrontato alla media calcolata tra il periodo 1974-2005. è molto probabile quindi che in concomitanza degli sprofondamenti la falda abbia subito un notevole innalzamento che purtroppo non è stato possibile quantificare per mancanza di indagini e misurazioni nel corso del 2005. si ricorda comunque che testimonianze di locali riportano di risalite di acqua almeno per i sinkhole più antichi. l’assenza della falda fino ad una profondità di otre 50 m dal p.c. evidenziata dalle ripetute misurazioni ai piezometri (intervallo maggio 2007-giugno 2008) evidenzierebbe comunque l’eccezionalità dell’inverno 2005 nel quale la circolazione idrica sotterranea doveva essere molto più attiva e sicuramente con una piezometrica più alta rispetto ai valori normali. le prime ipotesi sulla formazione dei sinkhole fig. 12 precipitazioni medie mensili per il periodo 1974-2005 confrontate con le precipitazioni totali mensili relative agli anni 19961997 e 2004-2005 (stazione pluviometrica del genio civile-avellino; da di crescenzo et al., 2008). mean monthly rainfall refereed to 1974-2005 compared with the total monthly rainfall calculated over the period 1996-1997 and 20042005 (genio civile-avellino rain gauges; from di crescenzo et al., 2008). 405nuove ipotesi sulla formazione ... lascerebbero pensare ad una lenta e graduale erosione nel tempo dei livelli sabbiosi per effetto di una circolazione idrica sotterranea caratterizzata da velocità abbastanza sostenuta e, localmente, con moto turbolento, attiva solo in periodi particolarmente piovosi. la lenta e graduale erosione sotterranea del livello sabbioso potrebbe aver creato una protocavità che si sarebbe evoluta sia lateralmente che verso l’alto fino a raggiungere dimensioni tali da non riuscire a sostenere la volta per gli sforzi di taglio indotti dal carico dei terreni sovrastanti che sono così collassati (fig. 11g e 11h). sulla base di questa ipotesi genetica, rimarrebbe tuttavia da chiarire l’eventuale recapito finale del materiale eroso. una ipotesi, tutta da dimostrare, potrebbe essere quella della presenza di un paleo inghiottitoio sepolto presumibilmente localizzato in corrispondenza del sinkhole sk5 ubicato in prossimità dei calcari del bordo sud orientale della conca endoreica dove già esistono in superficie analoghe morfologie carsiche (fig. 13). l’inghiottitoio sepolto potrebbe contribuire allo “smaltimento” del carico solido eroso per fenomeni di deep piping nelle aree più a monte. 6. discussione e conclusioni il problema della genesi dei sinkhole in aree alluvionali è ancora molto discusso. secondo diversi autori (tharp, 1997, 1999; nisio, 2003; nisio & salvati, 2004) i fenomeni di piping sinkhole, in aree alluvionali sarebbero generalmente da ricondurre alla presenza di cavità in rocce solubili all’interno di un substrato carsificabile che richiamerebbe il materiale di copertura fino ad avere un collasso improvviso in superficie. il “motore” di questo processo viene spesso individuato nell’azione di flussi verticali risalenti lungo zone fratturate o piani di faglia. altri autori, invece, popongono modelli diversi che escludono la presenza di un substrato carsificabile (hoffman et al., 1998; arkin & gilat, 2000; tomlinson & vaid, 2000) dimostrando che i vuoti responsabili del collasso si possono formare anche in terreni granulari per fenomeni di suffosione profonda. tale processo consiste nell’erosione meccanica di un terreno poroso per effetto dello scorrimento (subsuperficiale secondo la definizione originaria di castiglioni, 1986) dell’acqua in pressione che trova delle vie di scorrimento in cui passare con elevata velocità e moto turbolento. questo passaggio, provocando l’erosione del terreno, dà origine a canalicoli a sviluppo sub-orizzontale, condotti tubolari o cavità lungo le linee di flusso. analoghi fenomeni sono segnalati anche lungo il perimetro del mar morto e nella piana del fiume santa cruz a tucson in arizona (hoffman et al; 1998; arkin & gilat, 2000) dove la variazione da flussi laminari a turbolenti in zone discrete lungo il percorso delle linee di flusso in subalveo, causa il dilavamento dei materiali a granulometria sottile e la formazione di vuoti sotterranei. nel caso dei sinkhole di forino le indagini svolte confermano che i vuoti responsabili dei collassi si sono formati nei depositi di copertura limo-sabbiosi per fenomeni di suffosione profonda a profondità variabili tra i 20 ed i 25m ed in assenza di un bedrock carsificabile. i vuoti si creerebbero lentamente a causa dell’erosione meccanica operata da flussi turbolenti che asporterebbero i terreni a granulometria più sottile in particolari condizioni di notevole ricarica della falda. il fenomeno si instaura all’interfaccia tra terreni meno permeabili (flysch e tufi) ed i soprastanti terreni alluvionali sabbioso-limosi (fig. 13). successivamente il vuoto migrerebbe lentamente verso l’alto fino ad intercettare la superficie topografica e generare il collasso finale (fig. 11 e 13). si esclude quindi l’ipotesi della presenza e dell’influenza di eventuali cavità nel substrato carbonatico e anche quella di flussi profondi risalenti lungo faglie di cui, peraltro, non c’è nessuna evidenza superficiale. il contributo dei calcari e del carsismo in generale, sarebbe fondamentale invece per la veloce ricarica e l’aumento del carico idraulico nella falda multistrato dell’acquifero alluvionale (fig. 13). il substrato carsificato, inoltre, potrebbe spiegare fig. 13 rappresentazione schematica della formazione dei sinkhole nella piana di forino. 1) depositi piroclastici da fall alternati a paleosuoli e livelli alluvionali; 2) piroclastiti rimaneggiate in ambiente alluvionale; 3) ignimbrite campana; 4) detrito di versante; 5) depositi limoso-sabbiosi pre ignimbrite campana; 6) flysch miocenici; 7) substrato carbonatico mesozoico; 8) faglia; 9) sorgente; 10) circolazione idrica sotterranea nell’acquifero alluvionale. schematic representation of sinkhole formation in the forino plain. legend: 1) pyroclastic fall deposits, paleosoils alternated with alluvial deposits; 2) alluvial deposits; 3) campanian ignimbrite; 4) detritical talus; 5)alluvial sandy and silty deposits pre-campanian ignimbrite; 6) miocenic flysch; 7) mesozoic limestones; 8) fault; 9) spring; 10) underground water circulation inside alluvial aquifer. 406 s. del prete, i. giulivo & a. santo la scomparsa dei notevoli volumi di terreni asportati (poche migliaia di m3). infatti, lungo il bordo sud orientale della conca e laddove i calcari vengono a contatto diretto con l’acquifero piroclastico alluvionale, si potrebbe avere lo smaltimento di parte delle acque dell’acquifero alluvionale e del trasporto solido verso la falda profonda attraverso inghiottitoi sepolti (fig. 13). per quanto detto precedentemente non si esclude che nel sottosuolo della piana di forino siano presenti altri vuoti, non ancora noti perché profondi o perché non hanno ancora raggiunto la superficie topografica. in prima approssimazione, sulla scorta del censimento dei sinkhole effettuato e dell’assetto stratigrafico ed idrogeologico della piana di forino, la fascia di territorio che è da ritenere più suscettibile all’innesco di nuovi sprofondamenti si allinea in corrispondenza della zona di drenaggio preferenziale della falda dell’acquifero piroclastico alluvionale. tuttavia una zonazione più precisa su un territorio così vasto non potrà che essere realizzata a valle di ulteriori indagini e soprattutto attraverso la definizione dello schema idrogeologico locale ed il monitoraggio della falda nell’acquifero alluvionale. è da sottolineare, infine, che il modello qui proposto rappresenta solo uno dei possibili meccanismi di innesco di sinkhole in are alluvionali, in altri contesti ed in condizioni stratigrafiche ed idrogeologiche diverse non si escludono effetti della carsificazione in rocce solubili e, soprattutto, fenomeni di improvvisa liquefazione di corpi limoso-sabbiosi saturi il cui studio non può prescindere da un approccio anche di tipo geotecnico. bibliografia aa.vv. 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(1999) mechanism of upward propagation of cover collapse sinkhole. engineering geology, 52, pp. 23-33. tomlinson s.s., vaid y.p. (2000) seepage forces and confining pressure effects on piping erosion. canadian geotechnical jour., 37, pp. 1-13. waltham t., bell f., culshaw m. (2005) sinkholes and subsidence. springer, 382 pp. ms. ricevuto il 12 marzo 2008 testo definitivo ricevuto il 17 giugno 2008 ms. received: march 12, 2008 final text received: june 17, 2008 408 s. del prete, i. giulivo & a. santo imp.resoconto la stratigrafia in italia. inquadramento storico, stato dell'arte, dibattito sui problemi emergenti (breve resoconto sul workshop) maria bianca cita abstract: m. b. cita, stratigraphy in italy. gssps, geosites, mapping problems, quaternary definition. the second workshop of the renovated italian commission on stratigraphy, held during two days (september 10 and 11, 2007) at the 6th italian forum of geological sciences is here reported. after an initial historical introduction, special attention was given to the gssps defined or proposed in italy, to the geosites, to the relevance of stratigraphic principles in official geological maps. the newly published volumes of the catalogue of italian formations were commented and distributed. finally, the present debate on the status of the quaternary was discussed without reaching a consensus position. parole chiave: stratigrafia, piani standard definiti o proposti in italia, geositi, quaternario. keywords: stratigraphy, gssps, geosites, catalogue of italian formations, quaternary. il quaternario italian journal of quaternary sciences 21(1a), 2008 5-6 questo è il titolo di un workshop della durata di due intere giornate indetto dalla commissione italiana di stratigrafia (cis). conveners, il presidente m.b. cita e il vice-presidente b. d'argenio, coadiuvati dai due segretari m. balini e f. lirer. si tratta del secondo workshop indetto in occasione dei convegni biennali della fist. il primo si era svolto a spoleto due anni fa. come quello, anche il secondo workshop è stato seguito assiduamente e con molto impegno da diverse decine di partecipanti appartenenti al mondo accademico, al servizio geologico, a enti di ricerca e professionisti. notata la presenza occasionale anche di alcuni stratigrafi stranieri. il programma era stato studiato con cura in modo da presentare diversi temi con interventi tutti a invito. il primo tema (inquadramento storico) è stato trattato da g.b. vai, m.b. cita e b. d'argenio nell'ordine, illustrando sinteticamente la preistoria della stratigrafia italiana (g.b. vai), i codici di nomenclatura stratigrafica (m.b. cita) e l'influenza della geologia stratigrafica di azzaroli e cita (1963) sulla stratigrafia italiana (b.d'argenio). il secondo tema (stratotipi definiti/proposti in italia) ha visto la presentazione mediante power points molto ben documentati delle seguenti sezioni in fase di studio avanzato: prati di stuores (presso pralongià nelle dolomiti ampezzane) per il carnico gssp (presentazione m. balini) pizzo mondello (sicilia) per il norico (presentazione m. balini e p. di stefano) sezione di alano di piave nel trevigiano occidentale per il gssp del priaboniano e forse anche per il gssp del bartoniano (presentazione i. premoli silva e d. rio) monte conero per il gssp del cattiano (presentazione i. premoli silva e r. coccioni) infine f. lirer e s. iaccarino hanno presentato un ampio rapporto sull'attività della rcmns (regional committee on mediteranean neogene stratigraphy, di cui f. lirer è il segretario) sulla stratigrafia integrata e sul prossimo congresso che si terrà a napoli nel 2009, organizzato da s. iaccarino, b. d'argenio e f. lirer. alla fine della sessione sono stati presentati i tre piani proposti per il quaternario che sono stati illustrati e presi in seria considerazione anche nel congresso inqua tenutosi recentemente a cairns (australia) (presentazione di m. coltorti e f. antonioli) in assenza di e. di stefano, il calabriano è stato presentato da n. ciaranfi. sempre n. ciaranfi ha presentato anche lo ioniano, il cui gssp è stato correlato al limite brunhes/matuyama. infine f. antonioli e g.b. vai hanno presentato la sezione del mare piccolo di taranto, che potrebbe essere proposta come gssp del pleistocene superiore in sostituzione dell'eemiano e/o del tirreniano. il terzo ed ultimo tema della prima giornata (geositi e gssp) è stato di grande interesse per tutti. degli otto gssp definiti e ratificati finora in italia, soltanto quello del limite eocene/oligocene che si trova all'interno del parco del conero risulta essere segnalato adeguatamente e protetto (relazione r. coccioni e i. premoli silva). sui siti che definiscono il limite miocene/pliocene e la base dello zancleano, nonché il gssp del piacenziano che si trovano in provincia di agrigento, riferisce ampiamente p. di stefano, che intrattiene ottimi rapporti con le autorità locali, ma incontra grosse difficoltà nel raggiungere risultati concreti e definitivi a causa della mobilità delle autorità referenti. p. di stefano ritiene indispensabile un'azione coordinata a livello nazionale. l'intervento del vulcanologo l. lirer evidenzia un altro aspetto del problema, ossia la fruibilità turisticoculturale di aree di straordinario significato geologico. infine l'intervento dell'ingegnere l. bonci del dipartimento difesa dell'ambiente e della natura dell'apat mostra i risultati del censimento dei geositi effettuato dopo il workshop della commissione italiana di stratigrafia svoltosi a spoleto nel 2005 riguardanti i vari gssp. nel dibattito seguente si ravvisa l'opportunità di proporre concretamente al dott. a. todisco, direttore del dipartimento difesa dell'ambiente e della natura dell'apat di gestire direttamente i geositi dei gssp, che rappresentano un punto di riferimento mondiale di uno standard accettato da tutti gli organi preposti (proposta di p. di stefano). la seconda giornata si è aperta con il tema la stratigrafia nella cartografia geologica italiana. dopo una breve introduzione sul lavoro settennale svolto dalla commissione italiana di stratigrafia per conto del servizio geologico d'italia attraverso una serie di accordi di programma e contratti gestiti dal prof. p. manetti, la prof.ssa cita annuncia la pubblicazione degli ultimi quattro fascicoli della serie (quaderno 7) che illustrano formazioni definite in italia e validate dalla commissione italiana di stratigrafia nonché (negli ultimi due fascicoli) i cosiddetti nomi tradizionali. i fascicoli appena stampati sono esposti allo stand del servizio geologico al geoforum e tutti gli intervenuti sono invitati a ritirarne una copia durante il coffee break. i primi interventi, molto efficaci e convincenti, sono presentati da geologhe del servizio geologico. c. d'ambrogi illustra problemi e potenzialità delle ubsu per l'interpretazione e rappresentazione cartografica dei depositi marini. e. la posta tratta dei depositi plio-quaternari continentali dell'italia centro-meridionale. e. chiarini tratta dei depositi dell'arco alpino, della pianura padana e sardegna. altri interventi sull'utilizzo delle ubsu sono stati presentati da: giannandrea e principe sui depositi vulcanici del monte vulture (foglio melfi, ora pubblicato in un volume speciale della regione basilicata). g. pappone e b. d'argenio presentano il foglio salerno (cartografia terra e mare, raccolta dati durata oltre 10 anni). seduta interessante con interventi di m. coltorti e miccadei, anche se il dott. galluzzo, direttore del carg, lamenta l'assenza di molti operatori del settore. seguono gli interventi di l. sagnotti sulle variazioni paleomagnetiche secolari in record sedimentari marini e di g. muttoni su esempi di applicazioni della stratigrafia paleomagnetica alla definizione di gssp triassici. il tema più scottante all'interno del workshop avrebbe dovuto essere quello finale (la querelle sul quaternario). le discussioni non sono mancate, e hanno talvolta raggiunto toni accesi. al congresso inqua appena tenutosi a cairns la votazione per abbassare il limite del quaternario è passata senza voti contrari. ma secondo alcuni fra i presenti non è sufficiente che il quaternario venga riconosciuto come sistema e che la comunità internazionale sia incline o addirittura pronta ad adottare come sezioni-tipo quelle dell'italia meridionale, ma considerano irrinunciabile mantenere il limite attuale. questo atteggiamento ha fatto si che non si arrivasse a una posizione condivisa dalla comunità stratigrafica italiana. in conclusione il workshop è stato utilissimo per chiarire a che cosa serve veramente la commissione italiana di stratigrafia, che non può certo coordinare o migliorare la produzione scientifica degli italiani. essa ha due funzioni principali: 1) rappresenta l'interfaccia con la commissione internazionale di stratigrafia; 2) interagisce con il servizio geologico d'italia. la cartografia ha bisogno di una stratigrafia corretta, valida, aggiornata e la commissione ha bisogno del servizio. il nuovo legame con il dipartimento per la difesa dell'ambiente e della natura dell'apat che ci si propone di stabilire per la protezione dei gssp rappresenta il trait d'union tra le due interfacce. gli interventi programmati non avevano dato luogo alla presentazione di riassunti prima del workshop. essi sono stati raccolti e quelli presentati in tempo utile sono pubblicati in questo fascilo. milano, 1° ottobre 2007 6 maria bianca cita ms. ricevuto il 2 aprile 2008 testo definitivo ricevuto il 17 aprile 2008 ms. received: april 2, 2008 final text received: april 17, 2008 base traduzione italiana della terminologia presente in “guidelines for analysis and description of soil and regolith thin sections” (stoops, 2003) cristiano nicosia1, luca trombino1,2, georges stoops3 1dipartimento di scienze della terra, “a. desio”, università di milano. 2cnr idpa, milano. 3lab.mineralogy and petrology, dep. geology and soil science, ghent university, belgium. corresponding author: c. nicosia <cristiano.nicosia@unimi.it> riassunto: nicosia c. et al., traduzione italiana della terminologia presente in “guidelines for analysis and description of soil and regolith thin sections” (stoops, 2003). (it issn 0394-3356, 2010). diverse terminologie di riferimento sono state adottate negli anni per le descrizioni delle sezioni sottili nell’ambito della micromorfologia del suolo. di queste terminologie, tutte originariamente in lingua inglese, esistono traduzioni italiane più o meno complete, la cui tradizione è riportata nell’introduzione del presente contributo. mancava, tuttavia, all’interno del panorama italiano delle scienze della terra, una traduzione della più recente terminologia di riferimento, quella cioè proposta dal manuale “guidelines for analysis and description of soil and regolith thin sections” (stoops, 2003). si è dunque proceduto a redarre questa traduzione, mirando a limitare al massimo il numero di termini di nuova introduzione, quelli cioè non già presenti in precedenti traduzioni italiane od almeno nella letteratura di scienze della terra. si è inoltre voluto proporre un solo termine italiano per ciascun corrispettivo originale inglese, armonizzando inoltre quando possibile il termine italiano con quelli impiegati nelle traduzioni nelle altre lingue del gruppo neo-latino. abstract :nicosia c. et al., italian translation of the terminology contained in "guidelines for analysis and description of soil and regolith thin sections" (stoops, 2003). (it issn 0394-3356, 2010). various terminologies have been employed through the decades for description in soil micromorphology and micropedology. different italian translations of such terminologies, more or less complete, have been published. their succession is described in the introduction of the present article. nevertheless, an italian translation of the most recent terminology, the one contained in the manual “guidelines for analysis and description of soil and regolith thin sections” (stoops, 2003) was missing. such a translation has therefore been edited, aiming at limiting the introduction of new terms (e.g. terms that were not present in older italian translations or at least within the earth science literature). moreover, one single term has been proposed for its original english counterpart, trying to harmonise each term with the other translations belonging to the neo-latin language group. parole chiave: micromorfologia del suolo, terminologia, descrizione di sezioni sottili. keywords: soil micromorphology, terminology, thin section description. il quaternario italian journal of quaternary sciences 23(1), 2010 15-20 1. introduzione la micromorfologia del suolo è definibile come “un metodo per studiare campioni di suolo e di regolite con tecniche microscopiche ed ultramicroscopiche al fine di identificarne le diverse componenti e definire le loro mutue relazioni nello spazio e nel tempo” (stoops, 2003). con il presente articolo si intende offrire la sistematica traduzione in italiano dei termini per la descrizione micromorfologica presentati all’interno del manuale “guidelines for analysis and description of soil and regolith thin sections” di stoops (2003), nell’ambito di un progetto promosso dallo stesso autore per la traduzione in più lingue del manuale in questione (si veda ad es. stoops, a cura di 1986). la prima terminologia di riferimento per la micromorfologia fu proposta dal tedesco kubiena (1938) con l’opera “micropedology”. quest’ultima era caratterizzata da un approccio di tipo morfo-analitico (stoops & eswaran, 1986; stoops, 1993), che prevedeva un’analisi della fabric (organizzazione interna del suolo) utilizzando un criterio puramente morfologico, dal quale discendeva poi l’interpretazione in chiave genetica della morfologia osservata. in opere successive, kubiena (1948; 1953; 1970) introdusse invece un approccio morfo-genetico, nel quale a ciascun tipo di fabric veniva assegnato un nome, il quale rifletteva la posizione del materiale all’interno di un sistema genetico-evolutivo predefinito dallo stesso kubiena (stoops & eswaran, 1986; stoops, 1993). parzialmente ispirato all’approccio morfo-analitico di kubiena, fu pubblicato da r. brewer nel 1964 “fabric and mineral analysis of soils”, rivisto ed aggiornato poi nella seconda edizione (brewer 1976). si tratta del primo tentativo di definire un sistema organico per la descrizione micromorfologica di dettaglio dei suoli. l’opera introdusse alcuni concetti fondamentali quali quello di s-matrix (massa di fondo) e di pedological feature (figura pedologica), e propose inoltre una classificazione dei pori in base alla loro forma e modo di formazione. un terzo importante manuale di riferimento, ”handbook for soil thin section description” di bul16 c. nicosia, l. trombino & g. stoops lock et al. (1985) nacque dal lungo lavoro dell’international working group on soil micromorphology, costituitosi durante il terzo international meeting on soil micromorphology, tenutosi a wroclaw, polonia, nel 1969 (bullock et al., 1985; stoops, 2003). tale manuale si propose di utilizzare un approccio prettamente morfologico e non genetico, essendo esso mirato alla sola descrizione, e non all’interpretazione, delle sezioni sottili. una traduzione italiana pressoché completa dei termini dell’ “handbook” di bullock et al. (1985) è stata pubblicata da cremaschi & rodolfi (1990) e ripresa in parte da malucelli & gardi (1999). successivamente anche in cremaschi (2000) sono stati tradotti in italiano molti dei termini del testo in questione. tra le altre terminolgie di riferimento ricordiamo quelle incluse in “micromorphology of soils” (fitzpatrick 1984) e “soil microscopy and micromorphology” (fitzpatrick 1993). parte dei termini contenuti in quest’ultimo lavoro sono stati tradotti in italiano in malucelli & gardi (1999). il manuale di stoops (2003) è parzialmente basato sull’ “handbook for soil thin section description” di bullock et al. (1985) e costituisce la terminologia di riferimento di più recente pubblicazione nell’ambito della micromorfologia del suolo. 2. linee guida della traduzione e delle definizioni dei termini nella stesura della traduzione sono stati seguiti alcuni semplici criteri per la scelta degli equivalenti italiani dei termini inglesi. innanzitutto, sono stati favoriti i termini in italiano presenti in letteratura da maggiore tempo, e dunque quei termini che, confluiti nella terminologia di stoops (2003) direttamente da di bullock et al. (1985) erano stati tradotti a partire da cremaschi & rodolfi (1990). questo criterio è stato seguito nella speranza di minimizzare la quantità di termini nuovi che vengono introdotti col presente lavoro. per la stessa finalità, qualora ci si trovasse a dover tradurre termini “prestati” alla micromorfologia a partire da altre discipline, si è sempre tentato di impiegare l’equivalente italiano più largamente diffuso nella letteratura di riferimento per quelle stesse discipline. si è inoltre sempre stabilita un’unica traduzione italiana per ciascun termine inglese, al fine di evitare confusioni e sovrapposizioni, linea guida già formulata a partire da stoops (a cura di, 1986). un altro criterio è stato quello di scegliere termini che, quando possibile, fossero simili a quelli adottati nelle altre traduzioni all’interno del medesimo ceppo linguistico, nel nostro caso quello delle lingue neo-latine. una nota specifica merita il termine fabric, visto l’ampio utilizzo che ne viene fatto sia in micromorfologia che in altre discipline delle scienze della terra. il termine fabric è stato tradotto come “organizzazione spaziale”: esso può essere utilizzato nell’accezione di soil fabric (organizzazione spaziale del suolo) oppure in quella che fa riferimento all’organizzazione spaziale dei diversi cristalli che compongono un minerale (v. § 3.9). per ragioni di brevità e praticità è invece stato mantenuto in inglese il termine b-fabric anche nella forma non abbreviata di fabric di birifrangenza. 3. traduzione di fianco a ciascun termine inglese, tra parentesi, è indicata la pagina alla quale il termine compare nel testo di stoops (2003). l’ordine di presentazione ricalca l’ordine dell’opera originale. 3.1 concepts (concetti) arrangement (38): disposizione (spaziale) soil fabric (34): organizzazione spaziale del suolo fabric element (37): elemento dell’organizzazione spaziale integrated fabric (34): organizzazione spaziale integrata observed fabric (34): organizzazione spaziale osservata fabric unit (36): unità dell’organizzazione spaziale partial fabric (36): organizzazione spaziale parziale pattern (37) : modello 3.2 orientation and distribution patterns (modelli di orientazione e distribuzione) distribution: distribuzione orientation: orientazione basic (distribution, orientation) (38): distribuzione/orientazione fondamentale random (distribution, orientation) (38): distribuzione/ orientazione casuale clustered distribution (38): distribuzione/orientazione a gruppi linear distribution (38): distribuzione/orientazione lineare banded distribution (39): distribuzione/orientazione a bande fan-like distribution (39): distribuzione/orientazione a ventaglio interlaced distribution (39): distribuzione/orientazione intrecciata striated orientation (40): distribuzione/orientazione striata referred (distribution, orientation) (40): distribuzione/ orientazione riferita unreferred (distribution, orientation) (40): distribuzione/ orientazione non riferita perpendicular orientation (40): orientazione perpendicolare parallel orientation (40): orientazione parallela inclined orientation (40): orientazione inclinata radial (41): radiale bow-like (distribution, orientation) (41): distribuzione/ orientazione ad arco crescent (distribution, orientation) (41): distribuzione/ orientazione con andamento a mezzaluna related (distribution, orientation) (41): distribuzione/ orientazione relativa unrelated (distribution, orientation) (41): distribuzione/ orientazione non relativa galaxy fabric (45): fabric a galassia turbate fabric (45): fabric a tùrbine 3.3 c/f related distribution (distribuzione relativa g/f o grossolana/fine) c/f related distribution (42): distribuzione relativa g/f c/f limit: limite g/f c/f-ratio: rapporto g/f chitonic (42): chitonica enaulic (42): enaulica gefuric (42): gefurica monic (42): monica porphyric (43): porfirica close (c/f related distribution) (42): (distribuzione relativa g/f) chiusa single spaced (c/f related distribution) (42): (distribuzione relativa g/f) a spaziatura singola double spaced (c/f related distribution) (42): (distribuzione relativa g/f) a spaziatura doppia open (c/f related distribution) (42): (distribuzione relativa g/f) aperta 3.4 microstructure (microstruttura) 3.4.1 general (concetti generali) microstructure (57): microstruttura separation (degree of) (60): (grado di) separazione separated (60): separata accommodation (degree of) (62): (grado di) accomodamento accommodated (63): accomodata 3.4.2 voids (vuoti) void (63): vuoto poroid (64): poroide packing void (64): vuoto intergranulare complex (packing voids) (64): vuoti intergranulari complessi compound (packing voids) (64): vuoti intergranulari composti simple (packing void) (64): vuoto intergranulare semplice vesicle (64): vescicola channel (65): canale chamber (65): camera vugh (65): vacuo plane (65): vuoto planare moldic voids (65): vuoti da impronte 3.4.3 aggregates (aggregati) crumb (58): grumo granule (58): granulo ped (58): aggregato plate (59): lamina prism (59): prisma 3.4.4 microstructures (microstrutture) angular blocky (microstructure) (68): (microstruttura) poliedrica angolare subangular blocky (microstructure) (68): (microstruttura) poliedrica subangolare bridged grain (microstructure) (69): (microstruttura) a ponte channel (microstructure) (68): (microstruttura) a canali chamber (microstructure) (68): (microstruttura) a camere crumb (microstructure) (68): (microstruttura) grumosa granular (microstructure) (68): (microstruttura) granulare intergrain microaggregate (microstructure) (69): (microstruttura) a microaggregati intergranulari lenticular (microstructure) (68): (microstruttura) lenticolare massive (microstructure) (68): (microstruttura) massiva pellicular grain (microstructure) (69): (microstruttura) pellicolare platy (microstructure) (68): (microstruttura) laminare single grain (microstructure) (69): (microstruttura) a grani singoli 17traduzione italiana della terminologia presente in ... spheroidal (microstructure) (68): (microstruttura) sferoidale spongy (microstructure) (68): (microstruttura) spugnosa vermicular (microstructure) (68): (microstruttura) vermicolare vesicular (microstructure) (68): (microstruttura) vescicolare vughy (microstructure) (68): (microstruttura) a vacui 3.5 fine material (materiale fine) micromass (93): micromassa limpidity (86): limpidezza limpid (86): limpido speckled (86): maculato dotted (86): puntinato cloudy (86): nebuloso 3.6 organic matter (materia organica) organ residue (88): residuo di organismo tissue (residues) (88): (residui di) tessuto organic fine material (89): materiale organico fine cells (89): cellule cell residue (89): residuo cellulare amorphous organic fine material (89): materiale organico fine amorfo punctuations (organic) (89): puntuazioni (organiche) organic pigment (89): pigmento organico monomorphic o.m. (89): materia organica monomorfica polymorphic o.m. (89): materia organica polimorfica 3.7 groundmass (massa di fondo) 3.7.1 general (concetti generali) groundmass (91): massa di fondo b-fabric (95): b-fabric (f) o fabric (f) di birifrangenza undifferentiated (95): indifferenziata crystallitic (b-fabric) (95): (b-fabric) cristallitica speckled (b-fabric) (96): (b-fabric) maculata stipple speckled (b-fabric) (96): (b-fabric) maculata a puntini mozaic speckled (b-fabric) (96): (b-fabric) maculata a mosaico striated (b-fabric) (96): (b-fabric) striata circular striated (b-fabric) (97): (b-fabric) striata circolare concentric-striated (b-fabric) (97): (b-fabric) striata concentrica crescent-striated (b-fabric) (97): (b-fabric) striata con andamento a mezzaluna crosstriated (b-fabric) (97): (b-fabric) striata incrociata granostriated (b-fabric) (96): (b-fabric) granostriata monostriated (b-fabric) (96): (b-fabric) monostriata parallel striated (b-fabric) (97): (b-fabric) striata parallela porostriated (b-fabric) (96): (b-fabric) porostriata random striated (b-fabric) (97): (b-fabric) striata disordinata strial (b-fabric) (98): (b-fabric) striale unistrial (b-fabric) (98): (b-fabric) unistriale bistrial (b-fabric) (98): (b-fabric) bistriale kinking (b-fabric) (98): (b-fabric) a cuspide 3.8 alteration (alterazione) alteration (78): alterazione isomorphous (alteration) (80): alterazione isomorfa katamorphous (alteration) (80): alterazione catamorfa mesomorphous (alteration) (80): alterazione mesomorfa alteromorph (80): alterazione alteromorfa 18 cross linear (alteration pattern) (80): (modello di alterazione) lineare incrociato dotted (alteration pattern) (81): (modello di alterazione) puntinato irregular linear (alteration pattern) (81): (modello di alterazione) lineare irregolare linear (alteration pattern) (81): (modello di alterazione) per linee patchy (alteration pattern) (83): (modello di alterazione) a macchie pellicular (alteration pattern) (80): (modello di alterazione) pellicolare cavernous residue (alteration pattern) (83): (modello di alterazione) a residuo cavernoso organized residues (alteration pattern) (83): (modello di alterazione) a residui organizzati dispersed minute residues (alteration pattern) (83): (modello di alterazione) a residui minuti dispersi tubular (alteration pattern) (81): (modello di alterazione) tubolare boxwork (83): a comparti contact void (83): vuoto di contatto septa (83): setti 3.9 pedofeatures (figure pedologiche) 3.9.1 general (concetti generali) pedofeature (101): figura pedologica matrix pedofeatures (102): figure pedologiche della matrice intrusive pedofeature (103): figura pedologica intrusiva impregnative pedofeature (103): figura pedologica di impregnazione depletion pedofeature (103): figura pedologica di svuotamento fabric pedofeature (103): figura pedologica dell’organizzazione spaziale compound pedofeatures (126): figure pedologiche composta juxtaposed pedofeatures (126): figure pedologiche giustapposte superimposed pedofeatures (126): figure pedologiche sovraimposte imbricated pedofeatures (126): figure pedologiche embricate complex pedofeatures (127): figure pedologiche complesse deformed pedofeatures (128): figure pedologiche deformate dissolved pedofeatures (128): figure pedologiche dissolte fragmented pedofeature (128): figure pedologiche frammentate kink band fabric (128): fabric a bande cuspidate 3.9.2 coatings (rivestimenti) coating (106): rivestimento hypo-coating (106): iporivestimento quasi-coating (106): quasi-rivestimento internal (hypocoating, quasicoating) (106): (iporivestimento, quasi-rivestimento) interno external (hypocoating, quasicoating) (106): (iporivestimento, quasi-rivestimento) esterno crust (107): crosta micropan (107): crosta interna capping (108): ricoprimento link capping (107): ricoprimento continuo pendent (108): pendente crescent (coating): rivestimento a mezzaluna typic (coating) (108): rivestimento tipico nonlaminated (clay coating) (109): (rivestimento di argilla) non laminato microlaminated (clay coating) (109): (rivestimento di argilla) microlaminato laminated (clay coating) (109): (rivestimento di argilla) laminato layered (clay coating) (109): (rivestimento di argilla) stratificato compound layered (clay coating) (109): (rivestimento di argilla) stratificato composto 3.9.3 infillings (riempimenti) infilling (113): riempimento dense complete (114): denso completo dense incomplete (114): denso incompleto loose continuous (114): sciolto continuo loose discontinuous (114): sciolto discontinuo passage feature (114): figura di passaggio 3.9.4 crystals (cristalli) crystal intergrowths (116): accrescimenti cristallini framboids (116): framboidi biospheroids (75): biosferoidi 3.9.5 nodules (noduli) nodule (117): nodulo aggregate nodule (119): nodulo aggregato alteromorphic nodule (119): nodulo alteromorfico dendritic nodule (119): nodulo dendritico geodic nodule (119): nodulo geodico nucleic nodule (119): nodulo nucleico septaric nodule (119): nodulo septarico typic nodule (119): nodulo tipico orthic nodule (118): nodulo ortico anorthic nodule (118): nodulo anortico disorthic nodule (118): nodulo disortico lithomorphic nodule (118): nodulo litomorfico pedomorphic nodule (118): nodulo pedomorfico macrocrystalline (47): macrocristallino / macrocristallina microcrystalline (47): microcristallino / microcristallina cryptocrystalline (47): criptocristallino / criptocristallina idiotopic fabric (120): organizzazione spaziale idiotopica xenotopic fabric (120): organizzazione spaziale xenotopica hypidiotopic fabric (120): organizzazione spaziale ipidiotopica porphyrotopic fabric (121): organizzazione spaziale porfirotopica poikilitopic fabric (121): organizzazione spaziale pecilotopica 3.9.6 intercalations (intercalazioni) intercalation (121): intercalazione interlaced (122): intrecciata serrated (122): dentellata 3.9.7 excrements (escrementi) excrement (122): escremento sphere (123): sfera ellipsoid (123): ellissoide conoid (123): conoide c. nicosia, l. trombino & g. stoops 19 tailed conoid (123): conoide caudato pointed tailed conoid (123): conoide caudato appuntito cylinder (123): cilindro bacillo-cylinder (123): bacillo-cilindro polled bacillo-cylinder (123): bacillo-cilindro smussato bipointed cylinder (123): cilindro a due punte clonocylinder (123): clonocilindro grooved plate (123): placca scanalata mitoid (123): a nastro mammilated (excrement) (123): (escremento) mammellonato tuberose (excrement) (123): (escremento) tuberoso aging (of excrements) (124): invecchiamento (di escrementi) coalescence (of excrements) (124): coalescenza (di escrementi) disintegration (of excrements) (124): disintegrazione (di escrementi) 4. bibliografia brewer r. (1964) fabric and mineral analysis of soils. john wiley & sons, new york, 470 pp. brewer r. (1976) fabric and mineral analysis of soils. robert e. krieger publ. co., huntington, ny, 482 pp. bullock p., fedoroff n., jongerius a., stoops g., tursina t. 1985 handbook for soil thin section description . waine research publications, wolverhampton, 152 pp. cremaschi m. 2000 manuale di geoarcheologia. laterza, bari, 386 pp. cremaschi m. & rodolfi g. (1991) il suolo: pedologia nelle scienze della terra e nella valutazione del territorio. nis, roma. fitzpatrick e.a. 1984 micromorphology of soils. chapman and hall, london. fitzpatrick e.a. 1993 soil microscopy and micromorphology. j. wiley & sons, chichester, 306 pp. malucelli f., gardi c. 1999 traduzione e glossario di termini usati nella micromorfologia del suolo (translation and glossary of the soil micromorphological terminology). il quaternario, 12 (1), 17-24. kubiëna w.l., 1938 micropedology. collegiate press, ames, ia, 242 pp. kubiëna w.l., 1948 entwicklungslehre des bodens. springer-verlag, vienna, 215 pp. kubiëna w.l., 1953 the soils of europe. thomas murpby & co., london, 314 pp. kubiëna w.l., 1970 micromorphological features of soil geography. rutgers university press, new brunswick, nj. stoops g. (ed.), 1986 multilingual translation of the terminology used in the “handbook for soil thin section description”. pedologie, 36 (3), 337-348. stoops g., 1994 soil thin section description: higher levels of classification of microfabrics as a tool for interpretation. in: ringrose-voase a.j., humphreys g.s. (eds.) soil micromorphology: studies in management and genesis. developments in soil science, vol. 22, elsevier, amsterdam, 317-325. stoops g., 2003 guidelines for analysis and description of soil and regolith thin sections. soil science society of america. madison, winsconsin, 184 pp. stoops g., eswaran (eds.), 1986 soil micromorphology. van nostrand reinhold company, new york, ny. ms. ricevuto il 28 aprile 2009 testo definitivo ricevuto il 10 ottobre 2009 ms. received: april 28, 2009 final text received: october 10, 2009 traduzione italiana della terminologia presente in ... imp.rossi& studio macrosismico del terremoto dell’aquilano del 24 giugno 1958 antonio rossi1, andrea tertulliani1, maurizio vecchi1 1ingv istituto nazionale di geofisica e vulcanologia, roma (e-mail:a.rossi@ingv.it, tertulliani@ingv.it, vecchi@ingv.it) riassunto: a. rossi, a. tertulliani & m. vecchi, studio macrosismico del terremoto dell’aquilano del 24 giugno 1958. (it issn 03943356, 2005). questo lavoro presenta lo studio di revisione del terremoto che colpì la media valle dell’aterno il 24 giugno 1958 con magnitudo pari a 5.0. scopo della ricerca è quello di completare il quadro delle conoscenze su questo evento poco noto, ed inquadrarlo nel contesto della sismicità di area e in un possibile schema sismotettonico della valle dell’aterno. la revisione dei dati macrosismici ha contribuito a incrementare largamente il numero di località del piano quotato conosciuto dal catalogo parametrico dei terremoti italiani, portandolo da 14 a 223, ed a proporre nuovi parametri di sorgente del terremoto. l’intensità massima è lievemente diminuita rispetto a quanto noto finora, mentre risulta aumentato il numero delle località oltre la soglia del danno. abstract: a. rossi, a. tertulliani & m. vecchi, macroseismic study of the june 24, 1958 earthquake, l’aquila (central italy). (it issn 0394-3356, 2005). this paper deals with the macroseismic review of the june 24, 1958 event, that struck the middle aterno valley, near l’aquila, with m=5.0 and epicentral intensity of vii-viii mcs. the main goal of the study was to enlarge the knowledge about this event, comparing it to the historical seismicity in the area and to the seismotectonic context. research in public archives allowed us to retrieve unpublished documents useful in deepening the earthquake knowledge. following the revision the number of intensity points passes from 14, as in recent catalogues, to 223. the number of damaged localities increases from 12 to 19. the greatest contribution to the increasing of the knowledge of this earthquake comes from the re-appraisal of the seismic cards, hold in the ingv macroseismic archive. after the revision new source parameters have been computed according to gasperini and ferrari (1995) and gasperini et al. (1999): the epicentral intensity results vii mcs, and the me (macroseismic magnitude) remains fixed to 5.0 . parole chiave: terremoto, macrosismica, media valle dell’aterno, sismotettonica, sismicità storica. keywords: earthquake, macroseismics, middle aterno valley, seismotectonics, historical seismicity. il quaternario italian journal of quaternary sciences 18(2), 2005 101-112 1. introduzione il 24 giugno 1958 alle ore 06:07 gmt una forte scossa di terremoto interessò la media valle dell’aterno (appennino abruzzese) con una magnitudo pari a 5.0, calcolata all’epoca sulla registrazione della stazione di roma-ing (di filippo e peronaci, 1964). questo evento, che interessò una zona dove le conoscenze storiche sulla sismicità sono abbastanza incomplete, produsse danni in una limitata area a se della città de l’aquila e fu risentito fino a una distanza di oltre 90 km, a roma ed in vaste aree delle marche, umbria e lazio. l’interesse per questo terremoto risiede quindi nel fatto di costituire un elemento interpretativo importante per l’approfondimento delle problematiche sismiche di tutta la conca aquilana. infatti è l’unico evento di un certo rilievo nell’area negli ultimi 150 anni e presenta, come illustrato in seguito, chiare similitudini con il terremoto del 1461, massimo evento storico dell’area stessa (x grado). scopo del presente lavoro è la revisione macrosismica del terremoto del 24 giugno 1958, nel quadro della sismicità della media valle dell’aterno ed alla luce del notevole incremento dei punti di intensità apportato nel corso della ricerca, rispetto alla letteratura di riferimento. 2. inquadramento sismotettonico della media valle dell’aterno l’attuale regime tettonico dell’appennino abruzzese è principalmente caratterizzato da faglie normali con attività quaternaria, generalmente orientate nwse e ns. durante l’evoluzione della catena appenninica l’attività delle faglie normali principali ha portato, a partire dal pliocene, alla formazione di bacini intermontani, che ospitano sedimenti continentali plio-quaternari (fra gli altri: carraro & giardino, 1992; calamita & pizzi, 1994; galadini & galli, 2000; galadini et al., 2003). la sismicità di questo settore di catena è frequente ed elevata in energia, come ci documentano i grandi terremoti avvenuti nel corso della storia. possiamo ricordare i terremoti del 1349, 1703, 1706 e 1915 tutti eventi, secondo il gruppo di lavoro cpti, 2004 (d’ora in avanti cpti, 2004), con ix ≥ 10 (fig. 1). a questa sismicità possono essere associate diverse strutture sismogenetiche attive, come evidenziato da numerosi lavori pubblicati recentemente (vedi tra gli altri: giraudi & frezzotti, 1995; pantosti et al. 1996; cello et al., 1997; ce l l o et al., 1998; ga l a d i n i & ga l l i, 2000; d’addezio et al., 2001) (fig. 1). focalizzando l’attenzione sull’area aquilana dobbiamo citare il fatto che diversi autori mettono in relazione il forte terremoto del 2 feb102 a. rossi, a. tertulliani & m. vecchi braio 1703 (x mcs) con le strutture del sistema di faglie dell’alta valle dell’aterno; moro et al., (2002) associano questo evento alla faglia di m.te marine, che borda il segmento settentrionale dell’alta valle dell’aterno, mentre cello et al., (1998) propendono per un settore un po’ più meridionale dello stesso sistema di faglie. nessun terremoto può essere ancora associato alle faglie che bordano il sovrascorrimento del gran sasso, nonostante siano state recentemente studiate anche con analisi paleosismologiche (fra gli altri giraudi & frezzotti, 1995; galadini et al., 2003). in particolare galadini et al. (2003) hanno evidenziato un potenziale alto livello di hazard relativo alla faglia di campo imperatore, considerata “silente” in quanto non associabile storicamente ad alcun evento sismico. la media valle dell’aterno, oggetto del presente lavoro, è caratterizzata da sistemi en-echelon di faglie normali con direzione circa appenninica che hanno generato una serie di depressioni disposte a nwse dove si riconoscono tracce di attività tardo-pleistocenica (bertini & bosi, 1993) sviluppatesi in più fasi deformative a carattere “pulsante”. il sistema di faglie della media valle dell’aterno (calamita et al., 2000) ad attività quaternaria viene definito con una lunghezza dell’ordine dei 23 km. una ipotesi di collegamento tra le strutture dell’area e i terremoti era stata fatta da di filippo & peronaci (1964) i quali sottolineavano l’esistenza di un “campo fagliato”, dovuto al recente sollevamento degli altopiani aquilani, responsabile della sismicità locale. se analizziamo la sismicità storica di quest’area, notiamo che risulta essere meno energetica che nelle aree circostanti, come l’alta valle dell’aterno, la maiella e il fucino, con l’unica eccezione del forte terremoto aquilano del 1461 (x mcs), (baratta, 1901; cpti, 2004). il resto della sismicità, come citata nel cpti (2004), sembra dovuta a terremoti minori, i più significativi dei quali avvenuti soprattutto nel xvii secolo, la cui ubicazione resta tuttavia abbastanza incerta causa la scarsità di informazioni. questi eventi, 1762, 1786, 1791, 1889 citati in letteratura come terremoti aquilani, probabilmente anche per il ruolo di accentramento culturale di l’aquila, restano infatti misconosciuti e scarsamente documentati, come descritto nel paragrafo successivo. il carattere di una sismicità più moderata rispetto ai settori di catena circostanti, è altresì confermato dall’analisi della sismicità recente per quel settore di appennino centrale, mostrata in figura 1 per il periodo 1983-2003 (m>3.5), che appare piuttosto contenuta, sia in frequenza che in energia, e sembra quasi ignorare la media valle dell’aterno. 3. descrizione dei terremoti storici della media valle dell’aterno fra i terremoti conosciuti nei cataloghi e nei repertori sismici (vedi ad es. baratta, 1901; postpichl, 1985; boschi et al., 2000) si annovera come evento più fig. 1 inquadramento generale dell’area studiata. in figura sono mostrati i terremoti storici, come riportati nel catalogo parametrico dei terremoti italiani (cpti, 1999); lo schema semplificato delle strutture tettoniche, limitato al settore centrale dell’appennino abruzzese; la sismicità recente, 1983-2003 e l’epicentro del terremoto del 1958. nel riquadro è evidenziata la valle dell’aterno. general sketch of the study area. historical seismicity is reported as quoted in cpti (cpti, 1999). a simplified tectonic framework is shown, together with recent seismicity and 1958 epicentre. aterno valley is evidenced in the big square. antico nell’aquilano il terremoto del 1315, la cui definizione, sia come localizzazione che come effettiva consistenza è tutt’altro che chiarita. secondo cpti (2004) l’epicentro dell’evento è localizzato nella zona del sulmonese a circa 50 km a se di l’aquila. questa localizzazione non è condivisa dagli scriventi, in quanto le informazioni che supportano la revisione (boschi et al., 1997), derivano da una sola fonte peraltro vaga. a nostro avviso, considerando tutte le informazioni disponibili per questo evento (contenute principalmente in: postpischl 1985; boschi et al., 1997; boschi et al., 2000), il terremoto del 1315 trova una sua più giustificata localizzazione nell’aquilano, con una intensità epicentrale dell’ viii grado mcs. più consistenti sono le notizie riferite al terremoto del 26 novembre 1461 che è il più forte terremoto della zona in studio (x mcs). questo evento, composto da due scosse principali nella stessa giornata, sembrerebbe localizzabile nella media valle dell’aterno (fig. 2). le fonti primarie sono cronache coeve, ritrascritte dall’antinori nel xviii secolo (antinori, sec. xviii; casti, 1887). tali cronache narrano con grande dettaglio i danneggiamenti subiti dalla città de l’aquila, facendo però pochi cenni ai paesi dei dintorni. il piano quotato mostrato in cpti (2004) risulta essere limitato a 10 località, di cui 5 con i0 ≥ ix. queste località sono la città di l’aquila, di cui si conoscono le descrizioni dei danni ed una stima delle vittime, e alcuni paesi siti a se de l’aquila lungo la media valle del fiume aterno (fig. 2), onna, poggio picenze, castelnuovo e sant’eusanio forconese. dalle fonti coeve note sembra emergere che quest’ultime località subirono danni molto gravi. nel corso della ricerca è emersa inoltre una storia locale (giannangeli, 1974), ignota ai repertori tradizionali, che rifacendosi alla corografia degli abruzzi dell’antinori, permette di aggiungere la località di bariscianello, antico sobborgo di barisciano, nel piano quotato con una intensità pari al ix grado mcs. non si hanno notizie di danni da altre località nei dintorni, all’infuori di rocca calascio: una informazione consolidata nella tradizione locale attribuirebbe ad antonio piccolomini, verso il 1480, la ricostruzione di parte del paese e della rocca distrutti dal terremoto del 1461. non avendo trovato conferma di questa notizia nelle fonti consultate, abbiamo assegnato una intensità incerta a rocca calascio (fig. 2). ai due eventi principali del 26 novembre seguì una sequenza caratterizzata da molte scosse che durò circa due mesi, con forti repliche come quelle del 4 e del 17 dicembre e del 4 gennaio 1462, che aggravarono sensibilmente il quadro di danneggiamento. studi sismologici specifici su questo terremoto non esistono; esso viene tuttavia considerato nei repertori sismici e nei più moderni cataloghi (vedi ad es: baratta, 1901; boschi et al., 1995), che però non ne hanno di fatto mai ampliato lo stato delle conoscenze che restano ferme a quanto scritto da baratta (1901). e’ questo un caso abbastanza emblematico, nel panorama dei cataloghi sismici italiani, dove alcuni forti terremoti sono stati registrati soltanto da una o pochissime fonti, dalle quali derivano in seguito tutte le altre fonti, peraltro poco significative dal punto di vista dell’apporto alle conoscenze. i motivi di ciò, ben illustrati da castelli e camassi (2000), sono senz’altro legati al periodo storico e alla localizzazione dell’evento. il terremoto cade infatti in un’area molto lontana dal 103studio macrosismico del terremoto ... centro amministrativo del regno di napoli (napoli per l’appunto), e vicino all’unico centro subalterno (l’aquila), che avrà catalizzato l’interesse per il terremoto, portando a oscurare i fatti avvenuti nelle contrade più isolate, e lontane da un centro amministrativo rilevante. queste considerazioni, unitamente allo stato delle conoscenze, ci portano ad affermare che il terremoto del 1461 potrebbe aver causato un danneggiamento sicuramente più esteso di quello ad oggi conosciuto, limitato alla media valle dell’aterno. altro terremoto dell’area (cpti, 2004) con una intensità rilevante è quello del 6 ottobre 1762 (vedi fig. 2), ix-x a castelnuovo, ix a poggio picenze e vii a l’aquila. il terremoto pur essendo documentato da materiali di archivio (boschi et al., 1995), mostra un piano quotato molto scarno, composto da sole 6 locafig. 2 piani quotati dei terremoti del 1461 (a) e del 1762 (b) aggiornati dopo il presente lavoro. per quanto riguarda il terremoto del 1461 il piano quotato è arricchito di due località non presenti nel cpti, barisciano e calascio, quest’ultima con intensità dubbia. updated intensity maps of the 1461 (a) and 1762 (b) earthquakes. in the map of 1461 two new localities (barisciano and calascio), are present, in respect with cpti (cpti, 1999). however calascio is indicated very doubtful. 104 lità. nel corso della presente ricerca è emersa una ulteriore fonte di archivio1 che riporta notizia di gravi danni nel paese di barisciano e sue frazioni permettendoci di modificare l’intensità di barisciano nel piano quotato del cfti (boschi et al., 1995), passando da felt a viii grado. altri eventi sono segnalati nell’aquilano alla fine del 1700, precisamente 1786 e 1791, le cui fonti uniche sono alcune gazzette del tempo che descrivono danni nella città dell’aquila (gu, 1786; gf, 1786; gb, 1786; gu, 1791). in tabella 1 sintetizziamo i terremoti di probabile origine locale con intensità maggiore o uguale al vii grado. 4. stato delle conoscenze sul terremoto del 24 giugno 1958 secondo il catalogo parametrico dei terremoti italiani (cpti, 2004) l’intensità epicentrale (io) dell’evento è del vii grado mcs con una magnitudo (maw) pari a 5.2. cpti indica come elaborato di riferimento il database di osservazioni macrosismiche (dom4.1) di terremoti di area italiana al di sopra della soglia del danno (m o n a c h e s i & s t u c c h i , 1997) collegato al catalogo parametrico di terremoti di area italiana al di sopra della soglia del danno (camassi & stucchi, 1997). il database dom4.1 riporta un elenco di 14 località di risentimento con la relativa intensità espressa in gradi della scala mcs, con una imax di vii-viii grado. l'unico studio specifico pubblicato su questo terremoto è quello di di filippo & peronaci (1964) che riporta i valori di intensità per 14 località e solo per 4 di queste le descrizioni degli effetti. nell’articolo tuttavia viene riportata una carta delle isosisme relativa all’intero campo macrosismico con 135 punti, basata evidentemente su informazioni relative al risentimento in molte località non citate nel testo, ma in possesso degli autori, come ad esempio le cartoline sismiche (di filippo & peronaci, 1964). purtroppo aver pubblicato la sola mappa senza il riferimento del piano quotato non rende giustizia allo scrupoloso lavoro di di filippo & peronaci (1964), e soprattutto non è di molto aiuto agli studi successivi. nella tabella 2 sono sintetizzati i parametri del terremoto come riportati dalle principali fonti esistenti in letteratura. da quanto illustrato risulta che lo stato delle conoscenze sugli effetti del terremoto presenti nei cataloghi è basato su informazioni disponibile per 14 località, non essendo stato possibile per gli autori successivi utilizzare tutti i dati usati da di filippo & peronaci (1964) per la loro interpretazione. tale numero di località appare decisamente modesto per poter valutare correttamente sia l'area dei massimi effetti, sia la distri1 archivio stato aquila, affari speciali, ii serie, barisciano, busta iii bis, in giannangeli 1974. ”.. nel 1762 (*) alle ore 10 del 6 ottobre una violentissima scossa di terremoto distrugge quasi un terzo del paese. non conosciamo il numero delle vittime. la casa di 9 stanze adiacente alla chiesa di collerotondo è rovinata quasi completamente, danneggiata la chiesa di valleverde. si provvede a ripristinare il campanile. secondo una relazione di giannandrea giardini i danni sopportati dal paese ammontano a 39.339 ducati. l'università di barisciano invia una supplica al re per l'esenzione temporanea dei tributi sottoscritta da antonio salomone, giacchino giannangeli e francesco saverio de angelis notaio. ...”. anno me gi ho mi area epicentrale ix mm me 1315 12 03 09 30 italia centrale 100 6.0 1461 11 26 21 30 aquilano 100 6.6 6.1 1762 10 06 12 10 poggio picenze 95 6.0 5.4 1786 07 31 l`aquila 70 4.8 4.8 1791 01 l`aquila 75 5.1 1958 06 24 06 07 aquilano 75 4.8 5.0 tab. 1 eventi con probabile origine nella media valle dell’aterno come citati nel catalogo parametrico dei terremoti italiani (cpti, 2004). list of events with probable location in the middle aterno valley. the quotation of events is from the parametric catalogue of italian earthquakes (cpti, 2004). a b c d e f to (gmt) = 06:07 06:07:03,15 06:07:04 06:07 06:07 coord. epicent. = = 42.349 13.440 42.350 – 13.433 42.333 – 13.467 42.34013.477 io (mcs) = vii = = vii vii imax (mcs) vii = vii-viii viii vii-viii vii-viii h (km) = = 10 10 = = magnitudo = = m = 4.96 ml = 5.0 ms = 4.8 ms = 4.8 località di risentimento 2 2 14 * = 14 14 eventi periodo sismico 6 6 = = = = tab. 2 parametri del terremoto del 24 giugno 1958, ore 06.07, come riportati nei principali cataloghi e nelle altre fonti conosciute. a) ing, 1958; b) marcelli & pannocchia, 1963; c) di filippo & peronaci, 1964; d) postpischl, 1985; e) monachesi & stucchi, 1997; f) cpti, 2004. * il numero 14 si riferisce solo alle descrizioni esplicitamente riportate da di filippo e peronaci nel lavoro, e non tiene conto delle località riportate nella mappa. synthesis of the epicentral parameters related to the 1958 earthquake, as quoted in the current seismic catalogues and other known sources. a) ing, 1958; b) marcelli & pannocchia, 1963; c) di filippo & peronaci, 1964; d) postpischl, 1985; e) monachesi & stucchi, 1997; f) cpti, 2004. number 14 is only referred to the descriptions quoted by di filippo and peronaci (1964) in their work, and not to the points in the map. a. rossi, a. tertulliani & m. vecchi 105 buzione dell'intensità sul territorio. appare infine quantomeno singolare che nei lavori precedenti, tranne in di filippo & peronaci (1964) che però non esplicitano i dati, non vi sia traccia della consultazione delle cartoline sismiche, che venivano spedite da corrispondenti accreditati, all’indomani di un terremoto, all’ufficio centrale di meteorologia ed ecologia agraria (ucmea, 1958). queste rappresentavano infatti l’unica procedura di raccolta sistematica di dati macrosismici usata in quel periodo. 5. ricerca dei dati e assegnazione delle intensità uno degli scopi principali di questo lavoro è quello di allargare il più possibile la base dei dati di riferimento. le indagini, finalizzate allo studio macrosismico di questo evento, si sono svolte inizialmente attraverso la consultazione dei cataloghi e bollettini sismici, e della letteratura scientifica, in verità piuttosto scarsa; in secondo luogo attraverso la ricerca e la raccolta delle informazioni in archivi e biblioteche. essendo infatti il terremoto avvenuto in epoca abbastanza recente, abbiamo esaminato in primo luogo gli atti amministrativi, reperibili negli archivi pubblici, che si riferiscono alla corrispondenza tra le autorità del luogo e il governo. inoltre sono stati analizzati i quotidiani dell’epoca, specie per quanto riguarda le cronache locali, come fonti di notizie inedite per completare il quadro della conoscenza degli effetti. di seguito viene illustrato il contributo di ciascuna categoria di fonti consultate oltre a quello della letteratura scientifica conosciuta precedentemente descritto. quotidiani sono stati consultati i giornali quotidiani nazionali più importanti e le testate locali (vedi elenco in bibliografia) che riportano informazioni relative a un modesto numero di località di risentimento (22), di cui soltanto 8 non riportate da altre fonti; inoltre, la descrizione degli effetti è limitata a 7 località fra tutte quelle riportate, mentre per le altre 15 la notazione è di un generico risentimento da notare che il contributo dei quotidiani è relativo in gran parte a località distanti dall’area epicentrale. documentazione d’archivio la consultazione dei materiali conservati negli archivi pubblici è stata focalizzata alla provincia dell’aquila, in quanto l’area maggiormente interessata dall’evento è circoscritta alle vicinanze del capoluogo abruzzese. archivio di stato de l’aquila, fondo “gabinetto prefettura”. sono stati consultati 29 documenti consistenti nella corrispondenza tra le diverse autorità (sindaci, prefetto, carabinieri, ecc.), e sono emerse informazioni sul risentimento in 25 località della provincia de l’aquila di cui 8 non sono riportate da altre fonti. archivio dell’istituto nazionale di geofisica e vulcanologia (ingv) presso l’archivio dell’ingv è stata esaminata la collezione delle cartoline sismiche pervenute all’ufficio centrale di meteorologia ed ecologia agraria, ed ora conservate presso l’ingv. la consultazione ha consentito di incrementare in modo decisivo il numero delle località di risentimento conosciute e di migliorare nettamente la qualità dei dati attraverso più dettagliate descrizioni dei risentimenti in moltissime località. e’ stato così possibile avere notizie sul risentimento a grandi distanze dall’epicentro. il numero finale di località individuate tramite le cartoline è di 204. inoltre è stata reperita la “relazione sulla sismicità delle zone inscritte nell’elenco…” di de panfilis (1959), inedita, scritta per la commissione ministeriale per le norme edilizie dell’epoca. nel documento viene assegnata l’intensità a 18 località interessate dal terremoto del 1958 con una breve descrizione degli effetti. al termine della ricerca il numero di località rappresentate nel piano quotato è decisamente cresciuto, passando da 14 a 223, comprese anche 88 località con risentimento negativo, utili per circoscrivere l’area di risentimento. dalla tabella 3 si nota come il contributo decisivo venga dalla rilettura delle cartoline sismiche ed in misura minore da fonti di stampa e amministrative. fonte numero località cartoline sismiche 204 archivio di stato l’aquila 26 giornali 23 de panfilis (1959) 18 di filippo & peronaci, 1964 14 monachesi & stucchi, 1997 14 tab. 3 sono riportati i contributi dei diversi tipi di fonte utilizzati per l’individuazione delle località di risentimento. numero di località è in relazione al tipo di fonte consultata. per 35 località vi sono informazioni riportate in più fonti. number of localities quoted in each kind of source that has been retrieved. 35 localities are quoted in more than one source. dalla nostra ricerca emergono anche utili informazioni che consentono di prolungare il periodo sismico fino al 2 luglio 1958. sono state infatti individuate altre scosse associate alla piccola sequenza sismica che hanno contribuito ad accrescere il numero totale delle scosse, portandolo da 6 (ing, 1958; ma r c e l l i & pannocchia, 1963) a 14. 5.1 assegnazione dell’intensità l’intensità macrosismica è stata stimata utilizzando la scala mercalli-cancani-sieberg (mcs) (sieberg, 1930). tutte le informazioni provenienti dalle diverse fonti per ogni località hanno contribuito alla valutazione. in alcuni casi sulla cartolina sismica era riportata solo l’intensità, per cui, in mancanza di altre informazioni, abbiamo mantenuto il valore indicato. sul retro della cartolina sismica era infatti stampata una sintesi della scala mercalli a 10 gradi (mercalli, 1902), in modo che il corrispondente potesse confrontare direttamente le proprie osservazioni con la scala macrosismica e assestudio macrosismico del terremoto ... 106 gnare egli stesso il grado di intensità per la località in questione. la scala mercalli a 10 gradi e la scala mcs a 12 corrispondono abbastanza univocamente almeno fino al vii grado, evitando così di apportare conversioni alla valutazione. al termine dell’analisi delle fonti è stato possibile assegnare un valore di intensità a tutte le 223 località individuate (appendice 1), migliorando decisamente il quadro delle conoscenze sul terremoto. in particolare si è potuto ricostruire il piano quotato completo, dalle intensità più alte fino a risentimenti negativi, con i quali si può chiaramente definire l’area di risentimento generale dell’evento (vedi tabella 4 e figura 3). le località con danneggiamento passano da 12 a 19. il quadro del danneggiamento più grave è risultato limitato ad alcuni paesi, siti nella valle dell’aterno a se di l’aquila. l’intensità massima del vii grado mcs è stata assegnata alle località di onna, bazzano e s. demetrio ne’ vestini, dove si verificarono alcuni crolli parziali, qualche crollo totale e un danneggiamento lieve ma diffuso. più leggero il danno riscontrato in una quindicina di altri centri, con piccole lesioni più o meno diffuse e occasionalmente crolli parziali, tale da far stimare intensità del v-vi e vi grado. fra queste località anche la città dell’aquila dove sono documentate lesioni e qualche caduta di cornicione. 6. conclusioni nel corso degli studi sulla sismicità della zona dell’aquila, e in particolare della media valle dell’aterno, è stata intrapresa una ricerca per approfontab. 4 in tabella sono elencate le classi d’intensità con il relativo numero di località interessate. mettendo a confronto il presente lavoro con quanto riportato in letteratura risulta evidente l’incremento del livello di conoscenza sugli effetti del terremoto. (di-pe 1964 sta per di filippo & peronaci, 1964; mo-st 1997 sta per monachesi & stucchi, 1997). number of localities vs intensities classes after the revision in the present work. the improvement in the number of intensity points is very significant, if compared with that one of the former sources. (di-pe 1964 is for di filippo & peronaci, 1964; mo-st 1997 is for monachesi & stucchi, 1997). di-pe 1964 mo-st 1997 presente lavoro intensità mcs n. località n. località n. località vii-viii 2 2 vii 6 5 3 vi-vii 1 vi 4 5 8 v-vi 7 v 1 12 iv-v 12 iv 30 iii-iv 2 11 iii 40 ii-iii ii 11 nf 88 totale 14 14 223 fig. 3 campo macrosismico generale del terremoto del 25 giugno 1958. intensity map of the june 24, 1958 earthquake. a. rossi, a. tertulliani & m. vecchi 2000). tuttavia non possiamo trascurare del tutto il fatto che la particolare morfologia della zona, costituita da bacini alluvionali orientati nwse, abbia avuto un ruolo guida nella distribuzione del danneggiamento. una considerazione importante riguarda le aree del danneggiamento dei terremoti del 1461 e 1762 (figg. 3 e 4) che, seppur non ben definite, sembrano ricadere completamente nell’area di massima intensità del 1958. non è da escludere quindi una connessione tra le faglie riconosciute attive nell’area, alle quali non è stato finora associato nessun evento per mancanza di elementi osservabili sul terreno, e gli eventi qui discussi. ringraziamenti ringraziamo v. castelli, per le notizie storiche sui terremoti del 1786 e 1791; ringraziamo inoltre fabrizio galadini per le utili discussioni sui temi affrontati nell’articolo e diego molin i cui preziosi suggerimenti hanno contribuito al miglioramento del lavoro. 107 dire le conoscenze sul terremoto del 24 giugno 1958, il più recente tra i terremoti significativi della zona. i terremoti antichi con probabile epicentro simile a quello in studio sono stati quelli del 1461 e del 1762, il primo dei quali particolarmente dannoso (x grado) per i paesi della media valle dell’aterno. tuttavia la scarsità di notizie su questi eventi non permette di vincolarne con precisione localizzazione e dimensione, e per questo il terremoto del 1958 diviene un buon elemento di paragone per tutta la sismicità della media valle dell’aterno. durante la ricerca di nuove fonti, tuttavia, è stato possibile reperire notizie finora non note sui danni avvenuti nella località di barisciano in occasione di entrambi i terremoti, il che ci ha permesso di assegnare alla suddetta località l’intensità del ix grado per il 1461 e viii per il 1762 (fig. 2), modificando i piani quotati finora noti. la ricerca oggetto del presente lavoro ha portato a un grande incremento della conoscenza degli effetti del terremoto del 1958 rispetto a quanto presente nei cataloghi più recenti; il numero delle località del piano quotato aumenta infatti a 223 (vedere appendice 1). dalla figura 3 è possibile notare come l’evento abbia interessato una vasta regione dell’italia centrale, con l’area del danneggiamento limitata ad alcune località in provincia dell’aquila. l’intensità massima, rispetto al cpti, viene leggermente abbassata, e portata da vii-viii a vii. grazie al grande incremento di dati macrosismici e alla loro rivalutazione è stato possibile stimare nuovamente i parametri di sorgente relativi all’evento, utilizzando le procedure standard del cfti e cpti (g a s p e r i n i & f e r r a r i , 1995; gasperini et al., 1999) per i terremoti storici. i nuovi parametri, localizzazione, magnitudo e azimuth della sorgente sono riportati in tabella 5. la distribuzione delle massime intensità (fig. 4) ed anche la direzione dell’azimuth della ipotetica sorgente del terremoto ben si accorda con il quadro sismotettonico generale ed anche con quanto conosciuto delle locali strutture attive (bertini & bosi, 1993; calamita et al., 2000; galadini & galli, fig. 4 distribuzione delle intensità relativamente all’area epicentrale. con la stella è indicato l’epicentro proposto in questo lavoro. intensity map of the epicentral area and main tectonic structures of the area. the star indicates the epicentre. data lat lon me ntot naz azimuth rayleigh kuiper 06/24/1958 42.32 13.50 5.0 223 11 119± 23 <0.01 <0.01 tab. 5 nuovi parametri proposti per il terremoto del 24 giugno 1958. con me è indicata la magnitudo equivalente, ntot è il numero totale di dati macrosismici disponibili, naz è il numero di dati usati per il calcolo dell’azimuth di faglia. raylegh e kuiper rappresentano il livello di significatività degli omonimi tests. per i dettagli vedere gasperini & ferrari, (1995) e gasperini et al., (1999). new source parametres of the june 24, 1958 earthquake as proposed in the present work. me is the “equivalent magnitude”, that is assumed to represent the moment magnitude, ntot is the total number of macroseismic data, naz the number of data used for computing the source azimuth. last two columns show the significance levels of the raylegh and kuiper tests. for details see gasperini e ferrari, (1995) and gasperini et al., (1999). studio macrosismico del terremoto ... bibliografia antinori a. l. 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data 25 giugno 1958 ore 11,35. archivio di stato de l’aquila, gabinetto prefettura, b. 146.xxi.3b.ag. 1950-1958, fasc. scosse di terremoto del 24 giugno 1958. telegramma del capo di gabinetto della prefettura de l’aquila (per il prefetto de gennaro) al ministero dell’interno in data 2 luglio 1958. archivio di stato de l’aquila, gabinetto prefettura, b. 146.xxi.3b.ag. 1950-1958, fasc. scosse di terremoto del 24 giugno 1958. telegramma del comandante della sezione di avezzano dei cc alla prefettura in data 24 giugno 1958. archivio di stato de l’aquila, gabinetto prefettura, b. 146.xxi.3b.ag. 1950-1958, fasc. scosse di terremoto del 24 giugno 1958. lettera del sindaco di bugnara all’ufficio del genio civile de l’aquila in data 2 luglio 1958. archivio di stato de l’aquila, gabinetto prefettura, b. 146.xxi.3b.ag. 1950-1958, fasc. scosse di terremoto del 24 giugno 1958. lettera del comandante interinale del 5° corpo dei vigili del fuoco de l’aquila al genio civile de l’aquila in data 26 giugno 1958. archivio di stato de l’aquila, gabinetto prefettura, b. 146.xxi.3b.ag. 1950-1958, fasc. scosse di terremoto del 24 giugno 1958. lettera del sindaco di san pio delle camere all’ufficio del genio civile de l’aquila in data 1 luglio 1958. archivio di stato de l’aquila, gabinetto prefettura, b. 146.xxi.3b.ag. 1950-1958, fasc. scosse di terremoto del 24 giugno 1958. marconigramma dell’ingegnere capo del genio civile a lavabi, dispes e provoper senza data. archivio di stato de l’aquila, gabinetto prefettura, b. 146.xxi.3b.ag. 1950-1958, fasc. scosse di terremoto del 24 giugno 1958. lettera del sindaco di tione degli abruzzi all’ufficio del genio civile de l’aquila in data 26 giugno 1958. archivio di stato de l’aquila, gabinetto prefettura, b. 146.xxi.3b.ag. 1950-1958, fasc. scosse di terremoto del 24 giugno 1958. lettera del questore de 109studio macrosismico del terremoto ... località prov lat long i bazzano aq 42.337 13.454 70 onna aq 42.327 13.479 70 san demetrio ne' vestini aq 42.288 13.558 70 ocre aq 42.287 13.475 65 poggio picenze aq 42.32 13.541 65 barisciano aq 42.325 13.592 60 calascio aq 42.325 13.696 60 camarda aq 42.391 13.494 60 fossa aq 42.296 13.488 60 l'aquila aq 42.356 13.396 60 paganica aq 42.358 13.473 60 prata d'ansidonia aq 42.277 13.609 60 sant'eusanio forconese aq 42.288 13.524 60 cocullo aq 42.030 13.776 55 rocca di cambio aq 42.233 13.492 55 santo stefano di sessanio aq 42.343 13.644 55 sassa aq 42.352 13.299 55 scoppito aq 42.372 13.256 55 tione aq 42.203 13.636 55 aielli aq 42.081 13.591 50 bugnara aq 42.022 13.862 50 capestrano aq 42.266 13.769 50 località prov lat long i castelnuovo aq 42.295 13.628 50 gagliano aterno aq 42.126 13.701 50 isola del gran sasso te 42.501 13.661 50 molina aterno aq 42.148 13.735 50 montorio al vomano te 42.582 13.629 50 ortona de' marsi aq 41.997 13.728 50 ovindoli aq 42.136 13.516 50 pescina aq 42.025 13.657 50 rocca di mezzo aq 42.205 13.521 50 basciano te 42.595 13.74 45 borgorose ri 42.193 13.234 45 campli te 42.726 13.686 45 castel di ieri aq 42.114 13.743 45 castelli aq 42.489 13.712 45 civitella casanova pe 42.364 13.889 45 cugnoli pe 42.308 13.933 45 farindola pe 42.441 13.824 45 fontecchio aq 42.229 13.606 45 paganico sabino ri 42.190 12.997 45 spoltore pe 42.454 14.138 45 villetta barrea aq 41.776 13.935 45 antrodoco ri 42.415 13.076 40 l’aquila a s. e. il prefetto de l’aquila in data 25 giugno 1958. archivio di stato de l’aquila, gabinetto prefettura, b. 146.xxi.3b.ag. 1950-1958, fasc. scosse di terremoto del 24 giugno 1958. lettera del questore de l’aquila a s. e. il prefetto de l’aquila in data 25 giugno 1958. archivio di stato de l’aquila, gabinetto prefettura, b. 146.xxi.3b.ag. 1950-1958, fasc. scosse di terremoto del 24 giugno 1958. fonogramma del questore de l’aquila a s. e. il prefetto de l’aquila in data 24 giugno 1958. archivio di stato de l’aquila, gabinetto prefettura, b. 146.xxi.3b.ag. 1950-1958, fasc. scosse di terremoto del 24 giugno 1958. fonogramma del questore de l’aquila a s. e. il prefetto de l’aquila in data 24 giugno 1958. archivio di stato de l’aquila, gabinetto prefettura, b. 146.xxi.3b.ag. 1950-1958, fasc. scosse di terremoto del 24 giugno 1958. fonogramma della tenenza dei cc di tagliacozzo alla prefettura de l’aquila in data 24 giugno 1958 ore 14. archivio di stato de l’aquila, gabinetto prefettura, b. 146.xxi.3b.ag. 1950-1958, fasc. scosse di terremoto del 24 giugno 1958. lettera del commissario prefettizio di cocullo al provveditorato alle oo.pp. de l’aquila in data 4 luglio 1958. archivio di stato de l’aquila, gabinetto prefettura, b. 146.xxi.3b.ag. 1950-1958, fasc. scosse di terremoto del 24 giugno 1958. fonogramma della questura de l’aquila al genio civile de l’aquila in data 24 giugno 1958 ore 17,40. archivio di stato de l’aquila, gabinetto prefettura, b. 146.xxi.3b.ag. 1950-1958, fasc. scosse di terremoto del 24 giugno 1958. fonogramma dalla sezione cc di s. demetrio nei vestini alla prefettura de l’aquila in data 24 giugno 1958 ore 21,10. de panfilis m., (1959). relazione sulla sismicità delle zone inscritte nell’elenco allegato al rdl del 2211-1937, n.2105. capitolo vi. commissione per il riesame e l’aggiornamento delle norme tecniche concernenti l’edilizia antisismica. dattiloscritto dell’archivio ingv ucmea, (1958). “cartoline sismiche”. ufficio centrale di meteorologia ed ecologia agraria, presso archivio ingv. 110 ms. ricevuto il 25 gennaio 2005 testo definitivo ricevuto il 30 giugno 2005 ms. received: january 25, 2005 final text received: june 30, 2005 appendice i tabella a piano quotato delle località interessate dal terremoto del 24 giugno 1958 a. rossi, a. tertulliani & m. vecchi 111 località prov lat long i avezzano aq 42.032 13.426 40 campo di giove aq 42.011 14.045 40 cansano aq 42.004 14.013 40 cappadocia aq 42.006 13.282 40 castel castagna te 42.543 13.717 40 catignano pe 42.346 13.951 40 celano aq 42.084 13.546 40 civitella roveto aq 41.914 13.425 40 collarmele aq 42.059 13.628 40 collepietro aq 42.221 13.780 40 corfinio aq 42.124 13.843 40 luco dei marsi aq 41.959 13.471 40 montereale rm 42.522 13.246 40 monterotondo lt 42.054 12.623 40 notaresco te 42.658 13.894 40 offida ap 42.935 13.691 40 palena ch 41.984 14.138 40 petrella salto ri 42.294 13.068 40 raiano aq 42.102 13.814 40 rocca pia ap 41.932 13.977 40 roccafluvione aq 42.861 13.475 40 san benedetto dei marsi aq 42.005 13.622 40 scanno aq 41.903 13.881 40 sulmona aq 42.047 13.929 40 tagliacozzo aq 42.069 13.250 40 teramo te 42.659 13.704 40 torricella sicura te 42.658 13.656 40 turrivalignani pe 42.262 14.029 40 villa celiera pe 42.381 13.859 40 vittorito aq 42.125 13.817 40 amelia tr 42.558 12.413 35 ascoli piceno ap 42.853 13.578 35 leonessa ri 42.566 12.962 35 marcetelli ri 42.226 13.046 35 moscufo pe 42.428 14.055 35 penne pe 42.457 13.928 35 picciano pe 42.474 13.991 35 picinisco fr 41.645 13.868 35 tolentino mc 43.21 13.283 35 trasacco aq 41.958 13.537 35 vicoli pe 42.341 13.898 35 alanno pe 42.296 13.972 30 alvito fr 41.689 13.743 30 ari ch 42.291 14.262 30 arpino fr 41.648 13.610 30 balsorano aq 41.808 13.561 30 bucchianico ch 42.304 14.181 30 campotosto aq 42.558 13.369 30 casalincontrada ch 42.290 14.135 30 castel di lama ap 42.873 13.707 30 castel di sangro aq 41.784 14.108 30 località prov lat long i chieti ch 42.351 14.168 30 cittaducale ri 42.386 12.949 30 civita castellana vt 42.293 12.413 30 collecorvino pe 42.458 14.015 30 fara san martino ch 42.090 14.206 30 gioia dei marsi aq 41.953 13.693 30 guardiagrele ch 42.190 14.222 30 isola del liri fr 41.680 13.579 30 loreto aprutino pe 42.433 13.988 30 mandela rm 42.027 12.922 30 manoppello pe 42.257 14.060 30 monsampietro morico ap 43.067 13.556 30 nereto te 42.819 13.817 30 orsogna ch 42.219 14.283 30 palata cb 41.890 14.785 30 palestrina rm 41.839 12.891 30 palombara sabina rm 42.066 12.766 30 penna in teverina tr 42.493 12.355 30 pereto aq 42.059 13.101 30 pescara pe 42.464 14.214 30 rieti ri 42.404 12.867 30 rivisondoli aq 41.87 14.067 30 roccaraso aq 41.847 14.079 30 roma rm 41.895 12.482 30 settefrati fr 41.670 13.850 30 sora fr 41.718 13.613 30 tollo ch 42.339 14.319 30 vacri ch 42.296 14.231 30 villa vallelonga ch 41.869 13.623 30 zagarolo rm 41.839 12.831 30 arsoli rm 42.041 13.019 20 carpineto romano rm 41.605 13.084 20 cassino fr 41.489 13.831 20 ferentino fr 41.691 13.254 20 frosinone fr 41.636 13.341 20 genzano di roma rm 41.707 12.688 20 lanciano ch 42.230 14.390 20 paliano fr 41.805 13.057 20 pescasseroli aq 41.808 13.789 20 vieste fg 41.882 16.18 20 albano laziale rm 41.728 12.659 0 allerona tr 42.812 11.974 0 altino ch 42.102 14.331 0 alviano tr 42.59 12.297 0 alvignano ce 41.245 14.338 0 apice bn 41.118 14.931 0 aprilia lt 41.594 12.65 0 aquino fr 41.493 13.701 0 atina fr 41.619 13.800 0 aversa ce 40.974 14.207 0 bagnoli del trigno is 41.703 14.457 0 segue tabella a studio macrosismico del terremoto ... località prov lat long i bagnoregio vt 42.626 12.095 0 baschi tr 42.699 12.217 0 belforte del chienti mc 43.163 13.238 0 caianello ce 41.294 14.086 0 caiazzo ce 41.177 14.367 0 campoli appennino fr 41.737 13.679 0 canino vt 42.465 11.750 0 caprarola vt 42.327 12.238 0 casacalenda cb 41.740 14.849 0 castel campagnano ce 41.182 14.452 0 castel gandolfo rm 41.747 12.651 0 castel viscardo te 42.755 12.002 0 castelraimondo tr 43.209 13.057 0 castiglione in teverina vt 42.646 12.204 0 castorano ap 42.898 13.727 0 ceccano fr 41.568 13.334 0 cerreto sannita bn 41.285 14.560 0 civitella d'agliano vt 42.293 12.188 0 collelongo aq 41.885 13.584 0 contigliano ri 42.411 12.769 0 corbara tr 42.705 12.228 0 cori lt 41.642 12.916 0 dragoni ce 41.273 14.304 0 fabro tr 42.863 12.013 0 faeto fg 41.324 15.162 0 fermo ap 43.161 13.716 0 filignano is 41.544 14.055 0 fondi lt 41.358 13.427 0 formia lt 41.261 13.617 0 gaeta lt 41.218 13.568 0 gradoli vt 42.643 11.855 0 guglionesi cb 41.912 14.914 0 itri lt 41.29 13.532 0 jelsi cb 41.518 14.796 0 latina lt 41.467 12.903 0 macerata mc 43.3 13.453 0 maddaloni ce 41.038 14.387 0 manfredonia fg 41.623 15.908 0 località prov lat long i massafra ta 40.589 17.113 0 montaquila is 41.566 14.113 0 monte s. biagio ap 41.353 13.352 0 montefalcone appennino ap 42.987 13.46 0 montegallo ap 42.846 13.327 0 montegiorgio aq 43.130 13.537 0 morcone bn 41.34 14.664 0 norma lt 41.584 12.972 0 orsara di puglia fg 41.281 15.266 0 orvieto tr 42.719 12.113 0 pescocostanzo aq 41.889 14.065 0 pietrabbondante is 41.747 14.386 0 pioraco mc 43.178 12.986 0 pontecorvo fr 41.456 13.667 0 priverno lt 41.473 13.181 0 riofreddo rm 42.06 13.000 0 roseto valfortore fg 41.372 15.096 0 san giorgio la molara bn 41.27 14.919 0 san nicola manfredi bn 41.071 14.825 0 san severo fg 41.685 15.381 0 san venanzo tr 42.869 12.267 0 s. maria capua vetere ce 41.078 14.256 0 sefro mc 43.146 12.949 0 sepino cb 41.407 14.619 0 sermoneta lt 41.549 12.985 0 serrapetrona mc 43.176 13.189 0 solopaca bn 41.192 14.549 0 sparanise ce 41.190 14.097 0 teano ce 41.251 14.068 0 terracina lt 41.288 13.233 0 torre s. severo tr 42.671 12.063 0 troia fg 41.361 15.309 0 tuscania vt 42.420 11.870 0 vallecorsa fr 41.444 13.405 0 vallerotonda fr 41.549 13.914 0 venafro is 41.485 14.044 0 villamagna aq 42.332 14.237 0 volturino fg 41.478 15.125 0 112 segue tabella a a. rossi, a. tertulliani & m. vecchi imp.d'ambrogi problemi e potenzialità dell'utilizzo delle ubsu per l'interpretazione e la rappresentazione cartografica dei depositi marini chiara d’ambrogi servizio geologico d’italia dipartimento difesa del suolo apat via curtatone, 3 00185 roma <chiara.dambrogi@apat.it> abstract: c. d'ambrogi, unconformity-bounded stratigraphic units (ubsu) in the marine deposits geological mapping: problems and potentialities. the unconformity-bounded units (ubsu) are formal stratigraphic units defined as “body of rocks bounded above and below by specifically designated, significant and demonstrable discontinuities in the stratigraphic succession, preferably of regional or interregional extent” (salvador, 1994); in the national geological map at the scale 1:50,000 (carg project) these mappable stratigraphic units are recommended particularly for the continental quaternary successions and for the volcanic rocks (apat, 2003); however they are also used for not very deformed marine successions (piedmont tertiary basin and outer front of northern apenninic chain). in the four examined geological sheets the recognition of unconformities pairs the litostratigraphy. nevertheless only in the salsomaggiore terme and parma nord sheets ubsu are used as mappable units. in the cabella ligure sheet depositional units are defined across the entire basin, where the unconformities pass to their correlative conformities; these units are represented in a prototype map enclosed to the geological sheet. the coordination activities carried out for the carg project have produced a new cartographic symbol useful for mapping the unconformities also in undifferentiated litostratigraphic units. parole chiave: unità stratigrafiche a limiti inconformi; stratigrafia fisica; progetto carg; cartografia geologica. keywords: unconformity-bounded units; physical stratigraphy; carg project; geological mapping. il quaternario italian journal of quaternary sciences 21(1a), 2008 47-50 le unità a limiti inconformi (ubsu) sono unità stratigrafiche formali (salvador, 1994) definite come “corpi rocciosi delimitati alla base e alla sommità da significative unconformities”; l’identificazione delle unconformities risulta elemento essenziale per la definizione di tali unità stratigrafiche. nell’ambito del progetto nazionale di cartografia geologica alla scala 1:50.000 (progetto carg) l’utilizzo di tali unità è espressamente raccomandato per il rilevamento e la cartografia delle successioni quaternarie continentali e delle rocce vulcaniche (guida italiana alla classificazione e alla terminologia stratigrafica, 2003); tuttavia ha trovato spazio di applicazione, soprattutto come elemento di sintesi, anche nel caso di successioni di depositi marini debolmente deformati. le attività di coordinamento svolte nell’ambito del progetto carg hanno consentito di evidenziare alcuni aspetti problematici e le potenzialità connessi all’utilizzo delle ubsu, e più in generale all’applicazione di criteri di stratigrafia fisica, nell’ambito della rappresentazione cartografica di successioni di depositi marini. le esperienze maturate da diversi gruppi di lavoro impegnati nella realizzazione di alcuni fogli del progetto carg hanno evidenziato come, a fronte di approcci metodologici simili, si sia arrivati a scelte cartografiche molto diverse. per garantire il massimo dell’uniformità tra fogli si è giunti alla definizione di un nuovo simbolo che consenta di mantenere un elevato livello di informazione sulla presenza di superfici di discontinuità, pur utilizzando un criterio di tipo litostratigrafico. in questa nota si riportano, in carattere corsivo, periodi tratti dalle note illustrative e/o dalle legende dei suddetti fogli con lo scopo di riportare integralmente e sottolineare l’interpretazione e le scelte dei diversi autori. vengono di seguito descritte le scelte, diverse soprattutto in termini cartografici, adottate per alcuni fogli del bacino terziario piemontese (f. 157 trino e f. 196 cabella ligure) e del margine esterno della catena appenninica settentrionale (f. 180 salsomaggiore terme e f. 181 parma nord); tali fogli sono caratterizzati da un approccio metodologico comune, contraddistinto dal riconoscimento e dalla descrizione delle superfici di discontinuità ad affiancare la suddivisione litostratigrafica, ma si differenziano nella scelta delle unità stratigrafiche (litostratigrafiche o a limiti inconformi) cartografate. il foglio 157 trino (servizio geologico d'italia, 2003) presenta una successione paleogenico-neogenica distinta in unità litostratigrafiche, molte delle quali già ampiamente utilizzate e note in letteratura (argille azzurre, sabbie di asti); l'analisi dei caratteri litologici è stata accompagnata dall'individuazione, correlazione e gerarchizzazione delle superfici di discontinuità che separano i corpi rocciosi. tali superfici sono identificate dalla presenza di almeno una delle seguenti caratteristiche: discordanza angolare, disconformità erosionale, brusco salto di facies, indizi di tipo diagenetico, improv48 c. d’ambrogi viso cambiamento nella composizione dei sedimenti. le superfici così individuate hanno portato alla definizione di diverse ubsu che, per scelta degli autori, non sono state rappresentate in carta, ma riportate unicamente nello schema dei rapporti stratigrafici, che rappresenta una sintesi dell'assetto stratigrafico della successione e che costituisce il modello interpretativo dell'evoluzione tettonico-sedimentaria (dela pierre et alii, 2003); esse costituiscono, quindi, delle chiavi di lettura dei rapporti genetici che intercorrono tra le unità litostratigrafiche riconosciute e cartografate nel foglio. anche il foglio 180 salsomaggiore terme (servizio geologico d'italia, in stampa) presenta, per i depositi marini del messiniano superiore-pliocene inferiore p.p., un approccio misto, litostratigrafico e a ubsu; per i depositi marini e paralici del pliocene inferiore p.p.pleistocene inferiore, invece, gli autori hanno scelto esclusivamente il metodo delle ubsu. a differenza del foglio trino, però, le ubsu attribuibili ai depositi marini e marino-paralici mio-pleistocenici assumono, nel foglio salsomaggiore terme, il carattere di unità cartografabili, venendo descritte in legenda e rappresentate nel campo carta. l'applicazione dei criteri della stratigrafia fisica alla successione miocenica (post evaporitica) e pliocenica nell'ambito del progetto carg è un approccio di tipo sperimentale, (calabrese & di dio, in stampa). occorre sottolineare che la scelta degli autori di adottare i principi della stratigrafia fisica è legata alla disponibilità, in questo settore dell'appennino, di dati di sottosuolo (fig. 1a) a integrare quelli di superficie, nonché alla buona conoscenza dell'architettura deposizionale a scala regionale; le principali superfici di discontinuità riconosciute sono poste come limiti di supersintemi (fig. 1b), mentre le discontinuità minori sono utilizzate per definire sintemi e subsintemi. per evitare che tale criterio metodologico creasse problemi di collegamento e di nomenclatura delle unità, soprattutto con i fogli confinanti, è stato deciso di cartografare, per la porzione messiniano-pliocenica della successione, le unità litostratigrafiche note in letteratura (formazione a colombacci, formazione di vernasca, argille di lugagnano), e già adottate anche nei fogli limitrofi, piuttosto che unità a limiti inconformi, che compaiono solo come contenitori (sintema del t. ongina in fig. 1c). le esperienze maturate nell'ambito dei fogli trino e salsomaggiore terme sembrerebbero evidenziare la possibilità di un utilizzo delle ubsu anche per la rappresentazione cartografica di depositi marini, con l'indubbio vantaggio di fornire chiavi di lettura di sintesi dell'evoluzione dei bacini. tuttavia la scelta di cartografare le sole ubsu pone dei problemi quando si passa da zone in cui le superfici di discontinuità sono presenti e riconosciute a zone in cui tali superfici passano a quelle di continuità ad esse correlabili, come ben evidenziato dagli autori del foglio 181 parma nord (servizio geologico d'italia, in stampa). tale foglio è stato realizzato secondo lo stesso approccio metodologico del confinante foglio salsomaggiore terme, tuttavia, in legenda, nella descrizione del supersintema quaternario marino (pliocene sup.-pleistocene inf.), si evidenzia che nella parte settentrionale del foglio (nel sottosuolo) la superficie di discontinuità basale passa alla corrispondente superficie di continuità e, pertanto, non si potrà parlare più, per definizione, di supersintema quaternario marino, ma di sequenza deposizionale del quaternario marino. tale problema si estende a tutte le unità in cui viene suddiviso il supersintema; esse andranno considerate fig. 1 a) linea sismica e b) sezione geologica del f. 180 salsomaggiore terme (da apat, in stampa; parziali e modificate); sono state evidenziate le superfici di discontinuità che delimitano i supersintemi. c) schema delle ubsu adottate nel f. 180; il sintema del t. ongina è suddiviso in unità litostratigrafiche per garantire maggiore uniformità con i fogli limitrofi. a) seismic line and b) geological cross-section of the sheet 180 salsomaggiore terme (modified, servizio geologico d'italia, in print); the thick lines are the unconformity surfaces that define the supersynthems. c) ubsu scheme adopted for the sheet 180; to facilitate the correlation with the adjacent sheets the t. ongina synthem has been subdivided into lithostratigraphic units. sequenze deposizionali (sensu mitchum et alii, 1977) di rango gerarchico corrispondente. il passaggio concettuale da unità a limiti inconformi a sequenze deposizionali è sottolineato nella guida italiana alla classificazione e alla terminologia stratigrafica (2003) dove si ricorda che le ubsu sono definite sulla base delle superfici di discontinuità che le delimitano, mentre le seconde sono unità delimitate alla base e al tetto da discontinuità o dalle corrispondenti superfici di continuità. la possibilità di utilizzo delle stratigrafia fisica come tecnica utile a integrare il tradizionale metodo litostratigrafico è prevista nella guida al rilevamento della carta geologica d'italia 1:50.000 quaderni, vol. 1 (sgn, 1992): “data per scontata l'oggettività delle tradizionali unità litostratigrafiche, queste ultime devono essere arricchite di informazioni per permettere la lettura delle carte geologiche anche in termini di caratteristiche genetiche sequenziali delle successioni rocciose”; e ancora “i progressi delle conoscenze stratigrafiche e sedimentologiche ... impongono una sostanziale revisione dei criteri di studio. ... ciò si configura in pratica nell'uso di un approccio litostratigrafico integrato in tutti i casi possibili con criteri derivati dalla stratigrafia sequenziale”. tale tentativo di integrazione è stato proposto nel foglio 196 cabella ligure (servizio geologico d'italia, in stampa); il foglio è ubicato sul margine sud-orientale del bacino terziario piemontese ed è caratterizzato da unità liguri e subliguri su cui poggia, in discordanza angolare, la successione priaboniano-aquitaniana del bacino terziario piemontese (btp). l'approccio metodologico seguito per il rilevamento e la suddivisione dei soli depositi del btp è di tipo stratigrafico-deposizionale per evidenziare, mediante il riconoscimento delle superfici di discontinuità, la dinamica di crescita del bacino e per legarla con le fasi tettoniche che la controllano; tale approccio si dimostra particolarmente utile nelle zone marino marginali, settori chiave per leggere 49problemi e potenzialità dell’utilizzo delle ubsu ... l'evoluzione del bacino (marroni et alii, in stampa). le superfici fisiche di discontinuità stratigrafica sono segnalate sul terreno dalla presenza di alcuni caratteri, già elencati nel foglio trino, ma nel caso del foglio cabella ligure le superfici identificate sono state utilizzate per la definizione di “unità deposizionali ibride” (mitchum et alii, 1977; di biase, 1998) i cui limiti, a differenza delle ubsu, possono essere tracciati anche in zone dove le superfici inconformi passano a superfici di paraconcordanza. per poter garantire il massimo della correlabilità tra unità riconosciute nel foglio cabella e i fogli limitrofi, all'interno delle unità deposizionali, sono state mantenute le suddivisioni litostratigrafiche, in larga parte corrispondenti con le unità già utilizzate in letteratura; sono proprio le unità litostratigrafiche ad essere cartografate nel foglio alla scala 1:50.000, lasciando ad una carta prototipale (1:25.000) allegata la rappresentazione delle unità deposizionali e agli schemi a cornice del foglio e della carta prototipale le possibilità di lettura incrociata dei due diversi prodotti cartografici. dall'analisi dei fogli descritti emerge chiaramente che l'adozione di un criterio stratigrafico-sequenziale pone un'importante questione di restituzione cartografica delle unità in tutti quei casi in cui si passa dalle superfici di discontinuità alle superfici di continuità ad esse correlabili, dalle porzioni marginali a quelle distali del bacino su cui si sviluppano le sequenze deposizionali. conclusioni l'analisi dei fogli realizzati per il progetto carg mette in evidenza come, in particolari contesti geologici, l'utilizzo di criteri e metodi di stratigrafia fisica sia diventato elemento imprescindibile e necessario alla corretta interpretazione dell'evoluzione dei bacini sedimentari; tuttavia emergono chiaramente anche le diffifig. 2 esempio di rappresentazione cartografica di una superficie di discontinuità (a) attraverso il segno convenzionale “limite stratigrafico inconforme” e quello di “traccia di superficie di discontinuità” (b). example of cartographic representations of an unconformity surface (a): carg existing symbol “unconformity stratigraphic boundary” and new carg symbol “trace of discontinuity surface” (in the circle) (b). coltà connesse alla rappresentazione cartografica di unità diverse da quelle litostratigrafiche, più comunemente e diffusamente utilizzate. nell'ambito delle attività di coordinamento del progetto carg, il comitato d'area appennino settentrionale, partendo dal lavoro svolto dai diversi gruppi di ricerca per la realizzazione dei fogli, ha proposto una soluzione cartografica (http://www.apat.gov.it/ site/ _files/suolocarg/comitato_area_app_sett_febb2006.p df ) a tale problema attraverso la definizione di un nuovo segno convenzionale che renda possibile la massima integrazione tra l'approccio litostratigrafico e i criteri derivati dalla stratigrafia sequenziale, così come indicato e suggerito nel quaderni, vol. 1 (sgn, 1992); fermo restando che il metodo litostratigrafico rimane lo standard per la cartografia geologica ufficiale alla scala 1:50.000, il criterio stratigrafico-sequenziale costituisce l'elemento fondamentale per la produzione di elaborati di sintesi e di lettura integrata dell'evoluzione dei bacini sedimentari. il nuovo segno convenzionale “traccia di superficie di discontinuità” è sinonimo del preesistente “contatto stratigrafico inconforme” ma, a differenza di questo, consentirà di tracciare quelle porzioni di superficie di discontinuità che attraversano unità non ulteriormente distinte (es: abc in fig. 2a e 2b). il nuovo segno convenzionale darà la possibilità di rappresentare in carta un dato fondamentale per garantire la correlabilità tra unità riconosciute nelle aree marginali dei bacini e quelle riconosciute e distinte nelle aree distali degli stessi; tale informazione risulta indispensabile per la definizione di sequenze deposizionali e per la produzione di elaborati di sintesi a scala regionale. opere citate apat (2003) guida italiana alla classificazione e alla terminologia stratigrafica. quaderni serie iii, vol. 9, pp: 155. calabrese l. & di dio g. (in stampa) note illustrative della carta geologica d'italia alla scala 1:50.000 foglio 180 salsomaggiore terme. servizio geologico d'italia -apat, roma. calabrese l. (in stampa) note illustrative della carta geologica d'italia alla scala 1:50.000 foglio 181 parma nord. servizio geologico d'italia apat, roma. dela pierre f., piana f., fioraso g., boano p., forno m.g., violanti d. (2003) note illustrative della carta geologica d'italia alla scala 1:50.000 foglio 157 trino. 147 pp., servizio geologico d'italia apat, roma. di biase d. (1998) stratigrafia fisica, facies e significato dei conglomerati della val borbera (btp). tesi di dottorato, univ. di parma. marroni m., ottria g. & pandolfi l. (in stampa) note illustrative della carta geologica d'italia alla scala 1:50.000 foglio 196 cabella ligure. servizio geologico d'italia apat, roma. mitchum r.m. jr., vail p.r. & thompson s. (1977) seismic stratigraphy and global changes of sea level, part 2. the depositional sequence as basic unit for stratigraphic analysis. in: payton c.e. (ed.), seismic stratigraphy applications to hydrocarbon exploration. am. ass. petr. geol. memoir, 26, 53-62. salvador a. (1994) international stratigraphic guide. a guide to stratigraphic classification, terminology, and procedure . the international union of geological sciences and the geological society of america (eds.): pp. 214. servizio geologico d'italia apat (in stampa) carta geologica d'italia alla scala 1:50.000 foglio 196 cabella ligure. servizio geologico d'italia apat (in stampa) carta geologica d'italia alla scala 1:50.000 foglio 180 salsomaggiore terme. servizio geologico d'italia apat (in stampa) carta geologica d'italia alla scala 1:50.000 foglio 181 parma nord. servizio geologico d'italia apat (2003) carta geologica d'italia alla scala 1:50.000, foglio 157trino. servizio geologico nazionale (1992) carta geologica d'italia 1:50.000 guida al rilevamento. quaderni del servizio geologico d'italia, serie iii, vol. 1. 50 ms. ricevuto il 2 aprile 2008 testo definitivo ricevuto il 17 aprile 2008 ms. received: april 2, 2008 final text received: april 17, 2008 c. d’ambrogi biochronology of terrestrial mammals and quaternary subdivisions: a case study of large mammals from the italian peninsula maria rita palombo dipartimento scienze della terra università la sapienza, cnr, istituto di geologia ambientale e geoingegneria, p.le aldo moro, 5 00185 roma, italy. e-mail: mariarita.palombo@uniroma1.it abstract: palombo m.r., biochronology of terrestrial mammals and quaternary subdivisions: a case study of large mammals from the italian peninsula (it issn 0394-3356, 2009). defining and subdividing the quaternary on the basis of the mammalian fossil record from the continental realm is not a simple task due to the low degree of succession continuity and the scattered palaeontological evidence. moreover, even if the approaches to the quaternary are basically interdisciplinary and may combine many different chronological scales, establishing correlations between biochronology, biostratigraphy, chronostratigraphy, climatostratigraphy, and composite regional stratigraphy can often be very problematical. as far as biochronology is concerned, the marked geological, environmental and climatic diversity affecting different continental regions makes a correlation based on biological events difficult. indeed, “biochronological units” represent a time span during which faunas have a degree of taxonomic homogeneity and the corresponding “faunal complexes” have to be regarded as nonoverlapping and "ecologically adjusted groups of animals with specific geographic limits and chronological range" (te d f o r d, 1970). nevertheless, the stratigraphic lowest and highest occurrences of fossil remains (stratigraphic datum) within a given geographical area do not necessarily correspond to their actual first/last appearances (palaeobiological events) in time. this is due to diachroneity in palaeobiological events (i.e. local first and last appearances are strictly linked to dispersal, and the physical and biotic factors causing local evolution and extinctions) coupled with discontinuity in the continental sedimentary record, the rarity of deposits formed in a regime of virtually continuous sedimentation, the presence of important ecological barriers (that prevent some taxa from dispersing), environmental conditions (that affect the structure of palaeocommunities), and taphonomic and sampling biases. as a result, ongoing research, continuously yielding new data, make chronological frameworks thus far outlined, even if recent, open to significant improvements, and causing biochrons to be updated. this fact prevents any detailed biochronological framework from having widespread geographical significance. thus, only higher ranking biochronological units (land mammal ages, lmas) whose separation is based on palaeobiological events which have a wide territorial significance could be useful for chronological correlations. nonetheless, the transition between successive lmas does not always correspond to the boundaries separating marine series or stages. for instance, the villafranchian lma approximately began with the late pliocene (piacentian) and the transition from the early to the middle villafranchian lma happened around the pliocene/pleistocene (piacentian/gelasian) boundary, whereas the transition to the late villafranchian took place during the latest gelasian, and those from the villafranchian to galerian lma and from the galerian to aurelian lma respectively predated the beginning of the middle and late pleistocene. riassunto: palombo m.r., biocronologia dei mammiferi terrestri e suddivisioni del quaternario: l’esempio della faune a grandi mammiferi della penisola italiana. (it issn 0394-3356, 2009). definire e suddividere il quaternario sulla base del record fossile dei mammiferi continentali non è un compito facile ed anche se gli approcci al quaternario sono fondamentalmente interdisciplinari e tendono a combinare diverse scale cronologiche, stabilire correlazioni tra biocronologia, biostratigrafia, cronostratigrafia, climatostratigrafia, e stratigrafia regionale è spesso problematico. sebbene le unità basate su eventi biologici e climatici siano di largo uso nel quaternario continentale, il loro status non è stato formalmente definito e questo alimenta dubbi nell’approccio metodologico e confusione tra teoria (dato paleobiologico) ed operatività (dato stratigrafico). dal punto di vista teorico, le " unità biochronologiche" rappresentano un lasso di tempo durante il quale le faune locali hanno un certo grado di omogeneità tassonomica ed i "complessi faunistici” che caratterizzano le singole unità devono essere considerati “non-overlapping and ecologically adjusted groups of animals with specific geographic limits and chronological range" (tedford, 1970). tuttavia, l'’evidenza stratigrafica della prima e ultima presenza di un fossile nelle successioni affioranti in una determinata area geografica (dato stratigrafico) non corrisponde necessariamente all’effettiva prima e ultima comparsa di quel taxon nel tempo (evento paleobiologico). ciò si deve alla diacronicità degli eventi paleobiologici (ad esempio gli eventi locali di comparsa e scomparsa sono strettamente legati rispettivamente alla dispersione ed ai fattori fisici e biotici che regolano diffusione ed estinzione), alla discontinuità del record sedimentario continentale, alla rarità di depositi formati in regime di sedimentazione continua, alla presenza di barriere ecologiche (che limita o impedisce la dispersione di alcuni taxa in certuni territori), alle condizioni ambientali locali (che influenzano la struttura delle paleocomunita), a problemi tafonomici e di campionamento. questi limiti rendono instabili schemi biocronologici dettagliati basati su un record fossile regionale, in quanto essi sono fortemente dipendenti dal progredire delle conoscenze sul campo. fin dalla prima introduzione delle unità faunistiche (fus) (azzaroli 1977), sulle quale si fonda la biocronologia dei grandi mammiferi della penisola italiana, il progredire delle ricerche e la scoperta di nuove faune ha portato sia alla ridifinizione e/o eliminazionedi alcune fus sia alla creazione di nuove. ne consegue che, proprio in funzione della possibilità di discriminare singoli bioeventi, ogni schema biocronologico delle faune italiane risulta quanto più dettagliato tanto meno stabile nel tempo, nonché difficilmente confrontabile con gli schemi proposti per l’europa continentale. in realtà, l’utilizzo di unità biochronologiche di più alto rango (land mammal age, lma) la cui separazione è basata su eventi paleobiologici validi a grande scala e cambi di struttura dei complessi faunistici – meglio si presta a correlazioni su vasta scala. la transizione tra successive lma, tuttavia, non sempre corrisponde ai limiti che separano serie e stadi. per esempio, il villafranchiano inizia con il pliocene superiore (piacenziano), la transizione al villafranchiano medio potrebbe coincidere grosso modo con il limite pliocene/pleistocene (piacenziano / gelasiano), ma il passaggio al villafranchiano superiore avviene nel tardo gelasiano, e le transizioni villafranchiano/galeriano e galeriano/aureliano precedono, rispettivamente, l'inizio del pleistocene medio e superiore. key words: biochronology, biostratigraphy, plio-pleistocene, large mammals, itay. parole chiave: biocronologia, biostratigrafia, plio-pleistocene, grandi mammiferi, italia. il quaternario italian journal of quaternary sciences 22(2), 2009 291-306 292 m.r. palombo 1. introduction defining and subdividing the quaternary on the basis of the mammalian fossil record from the continental realm is not a simple task due to the low degree of succession continuity and the scattered palaeontological evidence. moreover, even if the approaches to the quaternary are basically interdisciplinary and can combine many different chronological scales, establishing correlations between biochronological, chronostratigraphical, climatostratigraphical frames and composite regional stratigraphy can be problematical (concerning italy, see e.g. de gi u l i et al., 1983; ra v a z z i, 2003; pa l o m b o, 2004a; pa l o m b o & sa r d e l l a, 2007 and references therein). with regard to terrestrial fauna, especially mammals, diachroneity in palaeobiological events coupled with discontinuity in the continental sedimentary record, the rarity of deposits formed in a regime of virtually continuous sedimentation, the presence of important ecological barriers (that prevent some taxa from dispersing), environmental conditions (that affect the structure of palaeocommunities), and taphonomical and sampling biases make the definition of isochronous boundaries, maybe of boundaries themselves, problematical. therefore, any biochronological framework is predisposed to change depending on new discoveries. during the latter half of the last century, study on the terrestrial mammals of the italian peninsula was developed mainly on the basis of large-sized mammalian taxa. the italian mammal biochronological framework builds on the pioneering work of azzaroli (azzaroli, 1977, 1982), who first introduced the “faunal units”(fu’s) as “biochrons”, defined on the basis of all the species from selected local faunal assemblages (lfa’s). like land mammal ages (lmas) which are the primary unit of north american vertebrate chronology (see teaford,1970; lindsay & tedford, 1990), fu’s represent and are defined by typical associations of mammalian taxa (biological entities), each living in non-overlapping slices of time. as suggested by lindsay (2003, pg. 222) for lma’s, fu’s could be defined as “a relatively short interval of geological time that can be recognized and distinguished from earlier and later such units (in a given region or province) by a characteristic assemblage of mammals”. although sometimes criticised (e.g. guerin, 1982, 1990), fu’s are general concepts, especially used by the italian scientific community. since the time of the fu’s introduction, italian palaeontologists have proposed new or revised some fu’s/lma’s (see e.g. de giuli, et al. 1983, torre, 1987; az z a r o l i et al., 1988; sa l a, et al., 1992; to r r e, et al. 1992; caloi & palombo, 1990, 1996; gliozzi et al., 1997, pe t r o n i o & sa r d e l l a, 1999; pa l o m b o et al., 2004; palombo, 2004a, 2007a; masini & sala, 2007; petronio et al ., .2 0 0 7 ) ( t abl e 1 ) . t h e i n t ro du c ti o n of n e w biochrons mainly depends on acquiring new data and discovering new fossiliferous assemblages, which makes possible, by means of ever more detailed biostratigraphical settings, increasingly accurate discrimination between bioevents. this paper’s aim is to outline the pricipal problems related to biostratigraphy/biochronology of large it a lia n ma mmal s, an d t o u pda t e t h e p rev i ou s biochronological schemes according to the most recent discoveries (table 2.3). 2. about chronostratigraphy, biochrono log y, b ios tra tigr ap hy a n d re la ted items: a short sketch as stated by lindsay (2003) chronostratigraphy the dominant method applied in the oceanographicmarine realm and biochronology the dominant method for the terrestrial realm are the prime conceptual methods for relating biological events to the geological time scale. the chronostratigraphical concept was introduced by schenck & muller (1941), who propos ed a n ew ‘ ‘c h ro n os t r at ig rap h ical ’’ h i era rch y (system, series, and stage) for the stratigraphical represent ation o f equiv alen t chr onolo gical in terv als (period, epoch, and age). recently, lindsay (2003, pg. 227) defined chronostratigraphy as: “the sequential ordering of geologic events, using biostratigraphic, isotopic-radiometric, and paleomagnetic data”. the concept of biochronology dates back the beginning of the 2 0 th c en t u ry , wh en w i l l i a m s ( 1 90 1 ) d efin e d a “biochron” as the absolute time extent of a peculiar faunal or vegetal association. later, te i c h e r t ( 1 9 5 8 ) described biochronology as ‘‘the dating of geological events by biostratigraphical methods’’, but did not ch ar act er is e b io ch ro n o lo gi cal t e rms , s u c h as ‘‘biochronological unit’’, and concepts relative to the biostratigraphical ones. due to that loose definition and to its ambiguous application, biochronology has never been discussed in any stratigraphical code (li n d s a y, 2003). up to the present day, the operation of organisi n g geological time on the basis of evidence provided by continental mammal faunas has continued to be a field plagued by interpretative and semantic confusion. be r g g r e n & va n co u v e r i n g (1978, pag. 39) tried to avoid ambiguity defining biochronology as ‘‘the organization of geological time according to the irreversible pr oces s of evo lut ion in th e o rganic con tin uu m’’. su bs equ en t ly , l i n d s a y (2 0 0 3 , pag . 2 2 7 ) def in ed biochronology as the “sequential ordering of biologic (and geologic) events, using morphologic differences that result from organic evolution (when applied to earth history)”. on the other hand, it is widely known that the discipline of biostratigraphy establishes the stratigraphical ranges of the taxa remains within superimposed sections, and verifies the relative age of rocks using the fossil data. biostrat igraphy is th e element of stratigraphy which focuses on “the distribution of fossils in the stratigraphical record and the organization of strata into units on the basis of their contained fossils” (sa l v a d o r, 1994, pag.55). but as claimed by sa l v a d o r ( 1994 , pag.55 ) biost rat igraphical units , including biozones, “vary greatly in thickness and geographic extent. ......the time they represent may likewise vary widely”. to avoid this issue, wa l s h (1998) defined the biochronostratigraphical units as “the sets of rock formed during biochrons, without reference to any particular stratigraphic section”. as a result, a biochronological unit should be characterised and defined as a span of time defined by biological evidences (palaeobiological datum), while a biostratigraphical unit as a body of rock strata defined by its fossil content (stratigraphical datum) (sc h o c h, 1989; sa l v a d o r, 1994). 293biochronology of terrestrial mammals and quaternary subdivisions: ... 294 2.1. in search of a stable biochronological frame for the terrestrial large mammals: utopia or feasible undertaking? as defined above, “biochronological units” represent a time span during which faunas are assumed to be characterised by taxonomical homogeneity and should be regarded as nonoverlapping and an “ecologically adjusted group of animals within specific geographic limits and chronologic range” (tedford, 1970). first/last appearan ce bioevents (palaeobiological events on which biochronology is based) have been the principal bases for establishing the chronological setting of continental mammalian faunas. however, the marked geological, environmental and climatic diversity affecting different continental regions, as well as the discontinuity in the continental sedimentary record, the rarity of deposits formed in a regime of virtually continuous sedimentation, the diachroneity in palaeobiological events (i.e. local first and last appearances are strictly linked respectively to dispersal, and the physical and biotical factors causing extinctions), taphonomical and sampling biases are responsible for the fact that the stratigraphical order of the highest and lowest occurrences (stratigraphical datum) of fossil remains of some taxa within a given geographical area, does not necessarily reflect the temporal order of the actual first/last appearances (palaeobiological events) of each taxon in time. indeed, a stratigraphical discontinuity within a sedimentary succession (whether due to erosional phases or sedimentation lacking) corresponds to a time span during which palaeobiological events do not yield a stratigraphical record. moreover, fossil remains of taxa characterising a given biochronological unit do not necessarily appear in each section because they were absent from the depositional environment for ecological or taphonomical factors. therefore, the time range of a paleobiological entity (either in general or in a given geographical area) cannot be unquestionably established by its fossil evidence. the lowest and highest stratigraphical records of a taxon, respectively correspond to the time “ante” or “post quem” when it actually originated and became extin ct (pa l o m b o 2004a). accordingly, it should be appropriate to discriminate taxon longevity from time slice of its fossil record, e.g. first/last historical appearance bioevents (fha/lha = first/last historical appearance) from “known data” of lowest and highest occurrences in a local stratigraphical section (llsdk/hlsdk = local lowest/highest known stratigraphical datum) (wa l s h, 1998; pa l o m b o & sa r d e l l a, 2007). on the other hand, mammalian biochronology is actually founded on fossil records available in the continental rocks, fha/lha bioevents can only be inferred from the lowest/highest occurrences of fossil remains in fossiliferous levels, maybe based on more than one continental stratigraphical section. hence, new discoveries may substantially change the chronological extent of already defined biochrons. indeed, the finding of a/some taxon/a (whose lha/lha were already regarded as markers of a biochrons) in significantly older/younger extends the theoretical time range of such a biochron, without changing its theoretical definition. as a result, ongoing research, continuously providing new data, makes chronological frameworks thus far outlined, even if recen t, open to s ignificant improv emen ts. some biochrons, consequently, will require revisions and updated definitions. 3. faunal turnovers, biochrons and quaternary subdivisions during the pliocene and pleistocene a series of climatic cycles caused latitudinal displacements of vegetation and biomes in europe and exerted great influen ce o n disper sal and dispers ion of mammalian species. as a result, the composition of regional faunas changed because of origination/ extinction and dispersal bio even t s . o n t h e i t alian p enin s u la, climat ic changes were a driving factor, at least as far as the two most important detectable faunal renewals are concer n ed: t h e ear ly t o m idd le vil la fra n ch ia n l m a (piacentian to gelasian, ~2.7–2.5 ma) and early to mi ddl e g al eri an l m a, t r an s it i on ( l at es t ear ly pleistocene, ~1.1–0.8 ma). faunas changed also at the end of the gelasian (middle to late villafranchian transit ion ) and at th e en d of t h e m iddle pleis to cen e (galerian to aurelian transition), but to a lesser degree (palombo, 2007b and references therein). 3.1 the beginning of the villafranchian and the warning signs of the already called “glacial pliocene” the list of early villafranchian taxa have been established on a number of lfa’s from piedmont (several localities in the villafranca d’asti area) and central italy (e.g. lower and upper valdarno, arcille, spoleto). palaeomagnetic data at fornace r.d.b. (villafranca d’asti) (lindsay et al., 1980, 1995) as well paleomagnetic calibration of the long sedimentary sequence outcropping at santa barbara quarry (lignitic lacustrine silty clays and sands, meleto clays of castelnuovo dei sabbioni lower synthem of the upper valdarno basin) (torre et al., 1996; bertini & roion, 1997; napoleone et al., 2003; ghinassi et al., 2004) illustrate that, at about 3.2 ma, the faunal association regarded as typical of the early villafranchian was already present on the italian peninsula. the early villafranchian lma (triversa fu) retains subtropical affinities typical of ruscinian mammals, which lived during the early pliocene, the most recent interval with a climate definitively warmer than today. pach y d er ms , mid dle s i zed ar t io da ct y la, an d perrissodactyla, mainly browsers or mixed-feeders inhabiting dense or clear forest, were still present along with arboreal/scansorial viverrids and arboreal omnivo r es , s u ch a s me sop it h ec u s mon s pess u la n u s, parailurus hungaricus and ursus minimus. on the other hand, the appearance of some taxa, such as leptobos s t e n o m e t o p o n a n d st ep h an o rh i n u s je an vi re ti ( = stephanorhinus elatus) (table 3), perhaps more linked to wooded parkland environment, testified to a change in faunal structure which can be correlated with the climatic cooling, which occurred at about 3.2/3.1 (km2 isotopic stage) (table 2). 3.2 early to middle villafranchian and the piacentian to gelasian transition the following montopoli fu is based on rich fauna from a site near montopoli (lower valdarno, tuscany), m.r. palombo 295 table 2 integrated chronological scheme for the middle pliocene to late pleistocene large mammalian record of the italian peninsula. biochronology of terrestrial mammals and quaternary subdivisions: ... 296 found in a fossiliferous level at the top of a shallowwater marine sequence of late pliocene age (benvenuti et al., 1995), calibrated with the gauss/ matuyama transition (li n d s a y et al. , 1980). the montopoli fu should correspond to the mn16b zone and was traditionally included in the early villafranchian lma (table 1), but the marked faunal turnover characterising the transition from the triversa fu to the montopoli fu recommends reg ar di n g it as t h e bas al u n i t o f t h e mi dd le villafranchian (caloi & palombo 1990, 1996). the faunal renewal from triversa to the montopoli fu can be regarded as a true turnover phase, due to the high percentage of last and new appearances, but also to the important structural changes in the faunal complexes, in both the herbivore and carnivore guilds. this is consistent with the significant global changes characterising the piacentian to gelasian transition (actually the beginning of the quaternary as proposed by several authors, see e.g. bowen & gibbard, 2007), with the permanent ice-sheet growth in the northern hemisphere, the first major influx of ice-rafted debris in the middle latitudes of the north atlantic, the onset of extensive loess deposition in china around the gauss/matuyama boundary (marine isotopic stage, mis, 104 to 100) (see inter alios ru d d i m a n et al., 1989; di n g et al., 1997; shackleton, 1997; partridge, 1997a, b; rio et al. 1998; bo w e n & gi b b a r d, 2007 and recently ratified by the international commission on stratigraphy, gi b b a r d & he a d, 2009), the profound changes in eurasian flora assemblages (see inter alios za g w i j n, 1974; gr i c h u k, 1997; su c et al., 1997). bioevents behind this faunal change (e.g. the so-called “elephant-e q u u s e v e n t ” , lindsay et al., 1980 ) likely occurred close to t he piacentiangelasian boundary, driven by climatic cooling, as well as by the effects of changes in the earth climate system: 19-23 ka cycles were superseded progressively by a 41-ka rhythm (orbital obliquity periodicity) accompanied by moderately increased amplitude climatic oscillations. the resulting increase in aridity and more intense seasonality triggered vegetation to reconstruct (suc et al., 1995, and references in bertini, 2003) and caused the disappearance of most forestdwelling taxa, especially small carnivores and arborealscansorial taxa, whereas new large grazers (the horse equ u s liven zoven si s) , mixed feeders ( a pr imitiv e mammuthus meridionalis, the medium-size gazella borb o n i c a) or even browsers (the deer eucladoceros falconeri) appeared (table 3). the taxonomical composition of the montopoli fu resulted primarily from the dispersal, mostly from eastern europe, of large to medium-sized herbivores, while evolutionary substitutions within surviving phyletic lineages were rather negligible. the faunal change indicates that forests gradually gave way to more open environments (including a r t e m i s i a steppe), alternating with warm temperate deciduous forests (see bertini, 2003). indeed, from an ecological point of view, the triversa faunal complex, which had a relatively high frequency of frugivores, developed in environments rather similar to those of modern forests, whereas the structure of the montopoli faunal complex shows some affi n it i es w it h t h o s e of mo de rn bu s h w oo dl an d (p a l o m b o & g i o v i n a z z o, 2 0 0 6 , p a l o m b o 2 0 0 7 b ) . moreover, this event can be considered as the beginning of a dispersal phase leading to a progressive increase in standing richness during the subsequent pli o cen e an d u p t o t h e be gi n n in g o f t h e ear ly pleistocene. a temperate interlude occurred between 2.5 and 1.8 ma; during this phase the mediterranean climate was established permanently in southwestern europe. a progressive faunal renewal took place, and some dispersal/origination bioevents led to a moderate faunal structural reconstruction of late middle villafranchian fauna. two fu’s have been proposed as characterising this time slice, the “saint vallier” and the costa san giacomo fu (table 1), but the italian “saint vallier” fu is loosely defined as being based on sporadic finds of taxa that also occur in the lfa’s assigned to the costa san giacomo fu. accordingly, the author is inclined to consider the italian late middle villafranchian lfa’s as belonging to only one fu. the “costa san giacomo” name is here retained despite the priority of “s a i n t vallier”. this is because of the rich fossil record of the corresponding lfa (costa san giacomo, anagni, latium), as well to stress the significance of the appearance on the italian peninsula of a wolf-like canid closely related to canis etruscus (a primitive representative of this phyletic lineage might be already present in the early villafranchian vialette lfa, lacombat et al., 2008). as here redefined, the italian costa san giacomo fu should roughly correspond to the mn 17”zone”. the faunal composition is similar to that of the preceding u n it as re ga rd s t h e pr es en ce o f t ax a s u ch as “pseudodama” lyra, eucladoceros tegulensis, gazella borbonica, or long-surviving taxa such as the cheetah, acin o n yx pa rd in en s is, t h e h u n t in g h ya en a chasmaporthetes lunensis and the proboscidean a . a r v e r n e n s i s , but renewed because of the first appearance, among others, of the middle-sized horse e q u u s stenonis, the goat gallogoral meneghini, and the spiral horned antelope gazellospira torticornis, all parkland dwellers, as well the large-sized and slender legged boar sus strozzii. the presence in the costa san giacomo of canis aff. c etruscus bears witness that the so-called “wolfevent” (az z a r o l i 1983, 1995) was already in progress. the carnivore guild renewal was a gradual phenomenon (sardella & palombo 2007, palombo et al., 2008), which developed throughout the latest gelasian and the earliest calabrian and involved several large and middlesized carnivores, such as the powerful scavenger, pachycrocuta brevirostris, the jaguar-like p a n t h e r a gombaszoegensis (= panthera onca toscana according to hemmer et all., 2003), the cooperative foraging canid, lycaon (xenocyon) falconeri, as well the coyote-like (but see ol i v e, 2006) canis arnensis (pa l o m b o et al. , 2008 and references therein). 3. 3 the lat e vi ll af ran chi an and the ge la sia ncalabrian boundary the latest gelasian faunal renewal involved both carnivores and herbivores: most pliocene and early gelasian species disappeared, particularly among herbivores, and new carnivores and herbivores progressively appeared (table 3). the renewal from the middle to late villafranchian lma, should be regarded as a dispersal phase (more than an actual turnover), which developed before and after the gelasian-calabrian boundary, and came to an end during the earliest early m.r. palombo 297biochronology of terrestrial mammals and quaternary subdivisions: ... calabrian, (pa l o m b o, 2004b, 2007a, b). the dispersal phase primarily involved carnivores, since among new taxa none belong to species which evolved in loco, whereas new appearances among herbivores were principally linked to the emergence of new species within pre-existing phyletic lineages (e.g. m a m m u t h u s , equus, eucladoceros, “pseudodama” and large bovids of subgenus leptobos), and subordinately, to immigration of large ruminants, mainly mixed feeders (e.g. procamptoceras and praevibos). these faunal changes indicate that forests or woodlands gradually gave way to more open en v iron men t s (in clu ding a r t e m i s i a steppe), but alternating with warm-temperate deciduous forests. the gradual faunal reconstruction from the latest gelasian to early calabrian took form within an interval of climatic transition, and was possibly driven both by climatic worsening (moderate average cooling mis 70 to58), and modification of internal competitive dynamics, the latter depending on the disappearances of some pre-existing key taxa and ensuing availability of ecological niches (palombo, 2007b). after az z a r o l i (1977) the late villafranchian, at this time considered as coincident with the early pleistocene (s e n s u ag u i r r e & pa s i n i, 1985), would include three fu’s: olivola, t and f (table 1). subsequently, a more recent, fourth fu, pirro was added, and the end of the late villafranchian was dropped before the jaramillo subchron (table 1). lfa’s assigned to the olivola and tasso fu’s are well-known from the upper valdarno basin, where fossil-bearing sediments of two stratigraphically superimposed units are exposed (de gi u l i & ma s i n i, 1 9 8 7 ; to r r e, 1987; az z a r o l i et al., 1988). magnetostratigraphy of these fossiliferous stratigraphical successions provides chronological constraints for olivola plus the tasso fu: in the upper valdarno area, lfa’s assigned to the tasso fu have been correlated to the top of the olduvai subchron (na p o l e o n e et al., 2003), which is around the gssp of the gelasian-calabrian boundary (la vrica section; ag u i r r e & pa s i n i, 1985), whereas lfa’s of the olivola fu (e.g. matassino and poggio ros so lfa’s) are “inferred as pre-olduvaian, not younger than 2.0 ma.” (na p o l e o n e et al. , 2003, pag. 308). the t ruct ure of th e faunal complexes of t he olivola and tasso fu’s are not very dissimilar, the latter being different essentially for the appearance, among others, of lycaon (xenocyon) falconeri (already present in the latest pliocene spanish fauna of fonelas p-1, ga r r i d o, 2008), equus stehlini (= equus senezensis stehlini, according to alberdi et al., 1998) and the stout bovid leptobos vallisarni. praeovibos is also recorded in the casa frata lfa, whereas gallogoral, gazellospira a n d procamptoceras were not reported (table 3). the occurrence of hippopotamus antiquus in the tasso fu is doubtful, since hippopotamuses from valdarno (already ascribed to the tasso fu), was probably retrieved from fossiliferous layers younger than those of the montervarchi succession (na p o l e o n e et al., 2003). on the other hand, the occurrence in the same stratigraphical layer of h. antiquus and leptobos aff. furtivus at piano dei cavalieri (rieti basin, latium) (masini 1989, ge n t i l i & ma s i n i, 2005), needs to be confirmed (see se g r e n a l d i n i & v a l l i a n d r ef ere n ces t h e rei n ) . accordingly, faunas assigned to ol i v o l a and ta s s o fu’s seem to be part of the same, progressive faunal renewal, and the hypothesis that they could represent a single fu cannot be ruled out. 3.4 the end of the villafranchian lma and the dawn of the galerian lma during the subsequent early pleistocene (farneta, pirro and colle curti fu’s) (table 2) an important ren ewal of fau nas occu rr ed: mos t of t he t yp ical villafranchian taxa disappeared or became rare while scattered bioevents led to the appearance of new species, either newcomers or ones evolved from preexisting taxa (table 3). the previously mentioned in cr eas e i n div er s it y t h r ou g h ou t t h e ea rl y l at e villafranchian (mainly via migrations and dispersal events) had possibly altered the palaeocommunity equilibria, and climate changes possibly removed keystone species causing new in traand inter-guild dynamics, leading mammalian communities to significantly reconstruct (palombo, 2007b). this is the reason wh y, despite the progressive appearance of new species (most of which will survive in the early middle pleistocene), last appearances prevailed, leading to a progressive reduction in diversity from farneta to colle curti fu’s (table 3). 3.4.1 farneta and pirro fu’s differences in taxonomical composition and structure between tasso and the following farneta fu are mainly related to changes in the herbivore guild and mirror the spread of open environments due to the decreas e in average t emperatu re, along wit h t he increase in dryness (be r t i n i, 2003; su c & po p e s c u, 2 0 05 ) . fo r in s t an ce , r h in o cer o se s s i mil ar t o stephanorhinus hundsheimensis were the possible ecological substitutes for stephanorhinus etruscus. t h e larger, mixed-feeder praemegaceros obscurus replaced the browser eucladoceros, and a more specialised form replaced the mixed-feeder “pseudodama” nesti. it is worth noting that br e d a & ma r c h e t t i (2007) doubtfully reported ?eucladoceros ex gr. ctenoides-dicranios and ?megaloceros obscurus from the main brown coal level (subunit 5) of the biogenetic unit of leffe formation (bergamo, northern italy), but the actual co-occurrence of these large deer needs to be fully substantiated. among carnivores, megantereon whitei, a saber-tooth cat of african origin, first appeared. the faunal renewal between the farneta and pirro fu (table 2) is marked by the appearance of some arriving african taxa, such as the large h i p p o p o t a m u s antiquus (magri et al., 2009), and (doubtfully) the cercopithecid t h e r o p i t h e c u s, a mixed-feeding genus whose extant species inhabits the high grasslands of ethiopia and eritrea (ro o k et al., 2004, but see pa t e l et al., 2007). this evidence of african immigration to southernmost europe stresses the importance of “out of africa” migratory waves, which occurred approximately around 1.6/1.3 ma (ma r t i n e zna v a r r o, 2004). other immigrants had an asian/european origin, as the ovibovine m e g a l o v i s and the rather stout bovine b i s o n (eobison) degiulii, the latter replacing the slender leptobovines. among perissodactyls, the middle-sized, slender limbed eq uu s alt iden s an d th e larg er e q u u s s u e s s e n b o r n e n s i s were certainly present, whereas equus stehlini is no longer recorded (see al b e r d i & palombo, in press for a discussion). among carnivores the middle-sized bone crusher canis mosbachensis first appeared and lycaon (xenocyon) lycaonoides substituted the less advanced l. falconeri. the dispersal of 298 m.r. palombo homo in the italian peninsula is testified by the finding of lithic implements in the karstic network of pirro nord, the local eponym of the pirro fu (ar z a r e l l o et al. , 2007). all in all, forest-dwelling taxa dwindled, whereas sp ecie s i nh a bit i ng pr air ies , s av an n a or st e ppes increased in percentage. the prevalence of dry and open environments at the time of the pirro fu (and colle curti fu as well) is confirmed by the great structural compatibility of these faunas with those of present day savanna/bushland habitats (pa l o m b o, 2007b). nevertheless, forest areas were still rather abundant, and woodlands spread in the more temperate and humid climatic phases, as evidenced, for instance, by the presence of the browser moose cervalces carnutur u m in the subunit 7 of leffe formation (bergamo, northern italy) (breda & marchetti, 2005, 2007), which deposited s hort ly befo re th e jaramillo subchron (muttoni et al., 2007). the occurrence at pietrafitta (umbria, central italy) of a vole close to microtus (allophaiomys) ex gr. m. ruffo i, a nd o f micro tu s (all oph aiomys) ch alin ei a n d mimomys pusillus in a large mammal fauna whose taxonomical composition and structure is consistent with that of the the farneta fu (ge n t i l i et al., 1996; ba r i s o n e et al. ,2006; pa l o m b o & gi o v i n a z z o, 2006), as well the presence at pirro nord of a more evolved m i c r o t u s ( a l l o p h a i o m y s ) ex gr. m. ruffoi, provide a correlation of the farneta and pirro fu with the earliest biharian (early biharian i, ma s i n i & sa l a, 2007). accordingly, and taking into account magnetostratigraphical dating of tuscan lfa’s assigned to olivola plus the tasso fu, the farneta and pirro fu’s developed during the pre-jaramillo early pleistocene, but the actual chronological extent of each fu is based only on biochronological estimates. 3.4.2 colle curti fu and the beginning of the mid pleistocene revolution (mpr) the transition from the early to middle pleistocene, mid-pleistocene revolution (mpr) (from about 1.2 to 0.6 ma) marks a fundamental change in the earth’s climate system (ma s l i n and ri d g w e l l, 2005) and represents a major episode in mammalian fauna reorganisation over the course of the cenozoic. orbital obliquity at 41-ka cycles was superseded progressively by a 100-125-ka rhythm, sustained by four-five precessional cycles, and accompanied by increased amplitude climatic oscillations (table 2). glacial phenomena intensified, temperature and moisture dropped notably, vegetational “exotic” essences, quite common in earlier floras, progressively disappeared and sustained climatic changes prevented these floral elements from becoming re-established (bertini, 2003). these changes spurred a shift in environments and constrained the geographical diffusion of a number of taxa, allowing dispersal waves that drove the reorganisation of large mammal communities. community rebuilding came to an end during the beginning of the middle pleistocene with the disappearance of the last surviving villafranchian species, such as pachycrocuta brevirostris and panthera gombazsoegensis (table 3). thus, at the time of mpr, fauna was charact eris ed by t he pres ence of lon g su rv iv in g villafranchian taxa and by a progressive increase in taxa, which also persisted into the middle pleistocene. such a framework of “mixed faunal elements” was regarded by authors either as a “transitional fauna” (bo n i f a y, 1978; az z a r o l i et al., 1988) or a distinct biochron (e.g. protogalerian sensu caloi & palombo, 1995, epivillafranchian sensu kahlke 2007 and previous papers; ‘latest villafranchian’ sensu koufos, 2001 or ‘final villafranchian’ spassov, 2003). on the other hand, if middle pleistocene faunas are clearly to be considered as ‘modern’ when compared to those from the villafranchian (pa l o m b o, 2004b), which criteria should be used to define the ‘theoretical’ boundary between the villafranchian and the following galerian lma? according to gl i o z z i et al. (1997) (table 1), the beginning of the galerian lma would be conventionally mar ked by t h e app ear an ce , a mon g o t h er s , o f praemegaceros verticornis, which is first recorded in italy at the colle curti lfa (colle curti fu, late early pleistocene, jaramillo subchron, coltorti et al., 1998). this giant deer has been recently found in the spanish fuente nueva 3 and the barranco leon lfa, dated at about 1.3 ma (ag u s t í & ma d u r e l l, 2003), which retain several villafranchian taxa, as does the colle curti lfa. moreover, the pirro nord (latest villafranchian) and the colle curti lfa’s exhibit a relatively high coefficient of similarity (pa l o m b o & va l l i, 2005). consequently, the col le c u rt i l f a s t il l l oo k s cl o se r t o th e lat es t villafranchian lfa’s than to the ensuing typical galerian ones, despite the llsdk of praemegaceros verticornis, cervalces latifrons (breda & marchetti, 2005), and possibly of subgenus b i s o n , the significant reduction in biodiversity shown by carnivores, as well as the innovative characteristics of the arvicolids (sa l a & ma s i n i, 2007). all in all, the the pirro and colle curti fu’s correspond to a time slice during which the villafranchian were gradually but not completely displaced by some typical galerian large mammals foreshadowing the coming of a new age. this evidence encourages a redefinition of the galerian lma (cf. pa l o m b o, 2004a and references therein, kahlke, 2007). 3.5. the mpr accomplishment and the onset of typical galerian mammalian faunas as above mentioned, the faunal renewal leading to the typical galerian faunas finds its origin in two distinct trends: 1) the progressive reduction in richness characterising late early pleistocene faunas (from the farneta to the colle curti fu’s), 2) the subsequent dispersal and the progressive spread in italy of taxa from eastern and central europe, that triggered a rapid increase in diversity at the beginning of the middle pleistocene (slivia fu) (palombo 2007b and references therein). it is noteworthy that this faunal change involved both carnivore and herbivore guilds at various times. the most important change in the former had already taken place prior to the jaramillo subchron, at the pirro–colle curti fu’s transition, with the disappearance of some large taxa, either flesh-eaters or bone-breakers, such as large canids and felids (table 3) (palombo et al., 2008 and references therein). this is the starting point for a reversal in the proportion of carnivores versus herbivores: indeed, across the early to middle pleistocene (slivia fu), the faunal renewal was strongly biased in favour of large herbivores, while the carnivore guild changed at a slower pace. taxa dispersed from eastern and central europe reached the italian peninsula in succession, thus leading an important and relatively 299biochronology of terrestrial mammals and quaternary subdivisions: ... rapid increase in diversity at the beginning of the middle pleistocene. these changing faunas represent a majo r l ar ge m ammal com mu n it y re or ga n is at i on throughout the quaternary. this dispersion phase was probably triggered by notable climatic changes that cor r es po n d t o t he o n s et o f t h e p ro n ou n c ed glacial–interglacial fluctuations as observed in the marine isotope record during the late early pleistocene (mis 25 to 22-20), while the progressive increase in diversity is seen as a consequence of the ensuing onset of w et t er cli mat i c co n dit i on s ( s ee p a l o m b o & gi o v i n a z z o, 2006 and references therein). instead of replacing any one species, these taxa enriched the herbivore guild, as well as the large mammal community as a whole (palombo, 2007b and references therein). even if, on a larger temporal scale, the progressive modification in the structure of large mammal faunas of th e i tali an penin s ula began befo re t h e jar amill o subchron, it was shortly before the early to middle pleistocene boundary that the major renewal and important ecological reorganisation of faunal complexes took place (palombo, 2007b). throughout the course of time (table 3), the local app ear an ces o f se v era l pa ch y der ms (e l e p h a s (palaeoloxodon) antiquus, mammuthus trogontherii, stephanorhinus kirchbergensis, stephanorhinus hemit o e c h u s), large (megaloceros savini, praemegaceros solilhacus), and medium-sized deer (capreolus capreolus suessenbornensis, cervus elaphus acoronatus a n d possibly dama clactoniana), as well as large (hemibos galerianus, bos primigenius) and middle-sized bovids (ovis ammon antiqua, hemitragus bonali), together with caballine horses (equus mosbachensis), all mainly mixed feeders or grazers, inhabiting open landscapes, bushlands or wooded grasslands, brought about a major change in the herbivore guilds (palombo, 2007b). among carnivores, crocuta crocuta first appeared (ponte galeria 2 lfa, pg2 sequence, about 750-650ka, milli & palombo, 2005 and references there in), whereas some other large carnivores, active hunters that were both flesh-eaters and scavengers [such as ursus deningeri, panthera fossilis, isernia lfa, about 600 ka (coltorti et al., 2005); a hyaena, hyaena prisca, whose taxonomical identification is still matter of debate at the ponte galeria 3 lfa (see ca l o i & pa l o m b o, 1980; pa l o m b o et al., 2008; tu r n e r et al., 2008), pg3 about 650-550 ka ( mi l l i & pa l o m b o, 2005); panthera pardus, valdemino cave lfa, isernia fu (sa l a, 1992) and isernia lfa (sala, 2006) ], had their lowest stratigraphical occurrence even later. these species, together with s. hundsheimensis, equus altidens, e. suessenbornensis, p. verticornis and b. shoetensacki are eponymous of the “typical” galerian faunas. most authors recognise in the “middle” galerian (sensu gliozzi et al., 1997) two fu’s, slivia and isernia which are clearly differentiated by the small mammals: mymomys savini (slivia lfa) and arvicola mosbachensis (isernia lfa). the small mammal association found at the archaeological site isernia la pineta (molise), represents the oldest toringian fauna recorded in italy to date (sala & masini, 2007) and represents the main renewal of small mammals throughout the galerian lma. pe t r o n i o and sa r d e l l a (1999) proposed the introduction of the ponte galeria fu (table 1), by these authors regarded as intermediate in taxonomical composition, and in age as well, between the slivia and isernia fu’s. this, because of the persistence of pachycrocuta brevirostris and panthera gombaszoeg e n s i s in the slivia fu, the exclusive occurrence of hemibos galerianus in the “ponte galeria fu” and the appearance of bos primigenius in the isernia fu. nevertheless, slivia and ponte galeria 2 lfa’s would be assumed to be part of the same fu due to the uncertain identification of some herbivores from slivia lfa, and the assumption that carnivores absent from the ponte galeria cu have in fact been found in the slivia lfa. unfortunately, there are no stratigraphical constraints for the age of the slivia fu, even if it can be cor relat ed with the lat e bih arian , which rou ghly extends from 0.95 to 0,6 ma, due to the occurrence of m. savini associated with that of microtus (stenoc r a n i u s) and microtus (terricola). conversely, in the roman basin, the integrated mammal biostratigraphy and sequence stratigraphy approach represents a valid tool to identify and to correlate physical and biological events. the biochronological and sequence-stratigraphical scheme proposed for the ponte galeria area, highlights that the sequence stratigraphical framework can constrain the possible chronological interval in which a bioevent, even if local, occurred (see mi l l i & palombo, 2005). the transition from the middle to late galerian (fontan a ranuccio fu) possibly occurred around 550–500 ka, due to the absolute age available for the lfa’s ascribed to isernia fu (notarchirico and isernia lfa’s , estimated age about 600 ka by le f é v r e & raynal, 1999; lefévre et al., 1999; and coltorti et al., 2005, respectively), and the fontana ranuccio fu (fontana ranuccio lfa, estimated age about 458 ka, biddittu et al., 1979). d u ri n g t h e la te m idd le g ale ri an ( fo n t an a ranuccio fu), “villafranchian” taxa were not yet recorded and the number of very large herbivores diminished (table 3). the occurrence of “galerian” equids and megacerines is doubtful and the specialised and slightly larger h. antiquus was replaced by h i p p o p o t a m u s a m p h i b i u s an d, amo ng car ni vo res , ursu s a rct os appeared as well as felis silvestris (table 3). in the second half of the middle pleistocene, increasingly different habitats supported increasingly varied faunas (cf. tr i a n t i s et al., 20 03), with new dynamic interspecific relationships. in fact, with the end of the galerian (fontana ranuccio fu) and the transition to the following aurelian lma, the most flexible species became the dominant group, the percentage of browsers increased and fauna progressively acquired modern characteristics (palombo 2007b and references therein). 3 .6 the a ur e li a n l ma an d the mi ddl e t o l at e pleistocene boundary gliozzi et al. (1997) proposed the aurelian as a new lma, differing from the galerian lma because of the appearance of taxa that constitute the core of the modern mammalian fauna, whereas some “galerian”species (such as horses, megacerine deer, m e d i u m s i z e d , bovid ovis ammon antiqua and hemitragus bonali, and large bovide, bison shoetensacki) were no longer pre300 m.r. palombo sent. according to gl i o z z i et al. (1997), three distinct, main faunal complexes could be detected: early, middle and late aurelian, characterised by an increase in the percentage of modern taxa. the early and middle aurelian were subdivided on the basis of faunal differences between two already created fu’s, torre in pietra and vitinia (ca l o i and pa l o m b o 1990, 1996, but see below), while for the late aurelian (mis 5-2) no characteristic fu’s have correctly been designated due to the monotonous taxonomical composition of the last interglacial faunas, as well the only sporadic occurrence of the so called “cold taxa” during the last glacial (but see petronio et al, 2007). 3.6.1 the aurelian lma and the question of vitinia fu the torre in pietra and vitinia fu’s have been defined on the basis of palaentological and stratigraphical evidence collected in the roman basin (caloi et al., 1998; but cf. palombo et al., 2004 and references therein). along the latium coast, rich lfa’s (torre in pietra, la polledrara di cecanibbio, collina barbattini, castel di guido, malagrotta) have been recovered either from fossiliferous deposits of the aurelia formation (conato et al., 1980) or the pg6 sequence, both correlated with mis 9 (milli & palombo, 2005). in these lfa’s, assigned to the torre in pietra fu the llsdk of canis lupus, ursus spelaeus and megaloceros giganteus is reported. in the same area, lfa’s uncovered in fossiliferous levels of the vitinia formation (conato et al., 1980) or pg7 sequence (milli, 1997), correlated with mis 7 (e.g. torre in pietra upper levels, vitinia level e, cerveteri) (palombo et al., 2003 and references therein) were previously ascribed to the vitinia fu’s (ca l o i & pa l o m b o, 1995; caloi et al., 1998) essentially because of the abundance of a primitive fallow deer, dama dama tiberina ( l o c a l l y associated with the pre-existing larger dama dama clactoniana), as well the appearance, among others of cervus elaphus with features similar to those of modern red deer and of equus hydruntinus. nevertheless, the structure and the taxonomical composition of the torre in pietra and vitinia faunal complexes are similar (palombo & mussi, 2001; palombo 2004), thus the division into two fu’s seems to be based on weak palaentological data, moreover new stratigraphical evidences call for a revision of these biochrons. in the 1990’s, two lfa’s, sedia del diavolo and monte delle gioie (today, no longer exposed due to of the intense urbanization of rome after world war ii), were assigned to the vitinia fu due to the abundance of dama dama tiberina remains in the alluvial deposits overlaying the “tufo lionato” (a lithified pyroclastic flow deposit from albani volcanic complex, dated 355 ka by karner et al., 2001) where also equus hydruntinus was found (ca l o i & pa l o m b o, 1995). ca l o i et al., (1998) correlated these bone-bearing deposits with the vitinia formation (mis 7), but recently the overlain ash flow has been dated at 285 ± 1 ka (marra & rosa, 1995; karner et al., 2001). following this new chronological data, the deposition of the fluvio-lacustrine sediments overlaying the “tufo lionato” at sedia del diavolo, occurred approximately during the time span between 355 and 285 ka (palombo et al., 2004). accordingly, the llsdk dama dama tiberina in italy is documented in deposits correlated with the mis 9, thus th e vitinia fu can not be cons idered a valid biochron. the lfa’s previously ascribed the torre in pietra and the vitinia fu’s have to be included in a single fu (named torre in pietra fu for priority reason) (table 1). summarizing, several bioevents characterised the beginning of the torre in pietra fu, as well as the beginning of the aurelian lma (subdivided into early and late aurelian) as here redefined: for instance canis lupus first appeared as well as ursus spelaeus that subs t i t u t e d u. deningeri, megaloceros giganteus, dama dama “tiberina, and bubalus murrensis (palombo, 2007 and unpublished data), the “steppe horse e. hydruntinus dispersed along the italian peninsula. furthermore, some new medium-sized taxa appeared, when more severe, arid climatic oscillations favoured the spread of “mountain” bovids (capra ibex and rupicapra) towards the southernmost regions of the italian peninsula, whereas galerian megacerine deer and horses, o v i s ammon antiqua and bison shoetensacki are no longer recorded (table 3). all in all, with the end of the galerian (fontana ranuccio fu) and the transition to the aurelian (torre in pietra fu), the most flexible species became the dominant group, the percentage of browsers increased and fauna progressively acquired modern characteristics. this is consistent with a moderate woodland expansion under increasingly mild climatic conditions characterising the interglacial phases, as well as the increase in north to south and east to west climatic gradients leading to the fragmentation of italian habitats. the structure of aurelian mammalian faunas was fully attained long before the beginning of the beginning late pleistocene, thereby the transition from galerian to aurelian lma predated the middle to late pleistocene boundary. 3.6.2 the late pleistocene the last interglacial lfa’s did not substantially differ fr om t h o s e r eco rd ed d u ri n g t h e lat e mi dd le pleistocene. the rare species bubalus murrensis is no longer present, while modern fallow and red deer substitute the late middle pleistocene subspecies, but the cor e o f t h e earl y au r elian fau na s kee ps ro u gh ly unchanged. although the last glacial phase caused a remarkable shift in the vegetational cover and in the distribution of mammals in europe, minor changes characterised the transition from the last interglacial to the last glacial faunal complexes on the italian peninsula (palombo, 2007b). during the last glacial, the faunal biodiversity increased with the arrival of some “cold” species, such as the typical, mammuthus primig e n i u s, the woolly rhinoceros coelodonda antiquitatis, the elk alces alces, inhabiting a “mammoth steppe”-like environment extending throughout the eastern po valley (gallini & sala, 2001). mammoth and woolly rhinoceros, as well the wolverine, gulo gulo, reached the tyrrhenian coast (latium) and were widespread in the south-eastern part of the italian peninsula, where alopex lagopus is also recorded, while rangifer tarand u s o nly reached th e wes tern mo st geog raphical boundary of the italian coast ( ca l o i & pa l o m b o, 1995; sa l a, 2005). the spread of “cold” species across the italian peninsula was profoundly conditioned by microclimate and physiography, and the taxonomical compo301biochronology of terrestrial mammals and quaternary subdivisions: ... sitio n and st ruct ure of l fa’s cou ld v ary greatly , depending on the geographical position of fossiliferous sites. that, coupled with the high percentage of extant species, prevent any fu to be fairly defined. moreover, the faunal assemblages were progressively depleted of some long-surviving galerian species. pachyderms wer e mo s t aff ect ed by cl ima t ic d et er io ra t io n . h i p p o p o t a m u s survived only until the end of the mis 5a, whereas elephas antiquus occurred also during mis 4 and s t e p h a n o r h i n u s was still present during mis 3, while panthera spelaea survived till the beginning of the holocene (boschian et al., 1995). all in all, the mammal faunas on the italian mainland maintained “temperate-cool” characteristics even during the cold-arid peaks of the last glacial. broadleaved wooded release “refugial” areas always existed on the tyrrhenian side of the peninsula, while the climate on the adriatic side was probably drier. therefore, some “warm” species remained on the italian peninsula longer than elsewhere, and turnovers in successive communities were less dramatic than in northern europe. with the deglaciation phase at the beginning of the ho locen e, dramatic mois tu re and vegetation change led to marked changes in mammalian faunas, particularly in their abundance, leading to the megafauna extinction. 4. conclusion several evidences show that, at least as far as the italian peninsula is concerned, global climatic changes are a contributing factor, especially in the first appearances of large mammals. this permitted the dispersal of new taxa, because mammals frequently reacted to the plio-pleistocene climate changes, expanding their distribution area or migrating rather than by evolving and producing new species. climate change, via migrations and dispersal events, caused diversity bursts but altered palaeocommunity equilibria, leading to new intraand inter-guild dynamics. we can also hypothesize that cause-and-effect relationships between climatic oscillations and faunal changes may be the cumulative result of the responses of individual species and that climatic changes could h av e ca u s ed th e r emo va l o f key s t o n e s p eci es . accordingly, migratory responses to climate change and physical-environmental disturbances, together with biotical interactions mainly contributed to faunal evolution in successive phases by discrete bioevents, maybe diachronous even in a restricted geographical area such as the western europe. this fact prevents any detailed biochronological framework from having wide geographical significance and predisposes it to change in the light of new findings. this is, e.g., the case of weakly defined fu’s such as the italian “saint vallier” (gl i o z z i et al., 1997) and the vitinia (ca l o i & pa l o m b o, 1990) fu’s, which stratigraphical evidences forced its deletion. moreover, increasing palaeontological and stratigraphical data sometimes leads us to better discriminate bioevents, highlighting the gradual renewal between successive biochrons, but blurring their clear identification as in the case of the olivola and tasso fu’s. thus, only higher rank biochronological units (land mammal ages, lmas) whose separation is based on palaeobiological events which have a wide territorial significance could be useful for chronological correlations. nonetheless, the transition between successive lmas does not always correspond to the boundaries separating marine series or stages. for instance, the villafranchian lma approximately began with the late pliocene (piacentian) and the transition from the early to the middle villafranchian lma happened around the pliocene/pleistocene (piacentian/ gelasian) boundary, whereas the transition to the late villafranchian took place during the latest gelasian, and those from the villafranchian to galerian lma and from the galerian to aurelian lma respectively predated the beg in n i n g o f t h e m idd le an d l at e pl eis t o cen e . concerning the villafranchian to galerian lma transition, from what has been previously reported on the biochronological patterns of large mammals, it possibly occurred close to mis 25, where ci t a & ca s t r a d o r i (1995, but see ci t a et al. , 2006) previously proposed lowering the early to middle pleistocene boundary. acknowlegement thanks are due to the organising committee of the aiqua congress “il quaternario nella cartografia carg2 for the opportunity to present this paper and to the anonymous reviewers for their helpful comments on the manuscript. the english version was revised by steven t. haire work supported by the project miur università 2007 c26a07lpwj. references aguirre e. & pasini g. 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(it issn 0394-3356, 2005). sulla base di uno studio di fotografie aeree, di un’analisi cartografica e di rilievi geologici e geomorfologici di dettaglio, viene studiato il basso versante nord-orientale dell’edificio vulcanico etneo, nel tratto compreso tra capo schisò e la foce del torrente macchia. si riscontra che l’attività di un sistema di faglie, sinora non descritto in letteratura, ha esercitato una profonda influenza sulla topografia, sulla rete idrografica, sull’andamento della linea di costa e, presumibilmente, sulla dislocazione di alcuni delta subacquei; due faglie hanno formato un graben che ha deviato il fiume alcantara; una colata lavica, riversandosi lungo la valle fluviale, ha fossilizzato questo graben; altre faglie hanno sbarrato piccoli corsi d’acqua con conseguente formazione di stagni costieri; dall’analisi delle carte nautiche si ipotizza che parte dei delta subacquei dei corsi d’acqua drenanti la zona abbia subito uno scorrimento destro valutabile in 500 metri. dall’analisi dei cataloghi dei terremoti non risulta alcuna attività sismica, in tempi storici, collegabile a questo sistema di faglie; altre fonti descrivono una sismicità locale legata alla riattivazione, nel dicembre 1795 e nel marzo 1847, del vulcano di fango noto come “salsa di fondachello”, e alla sua distruzione avvenuta nel mese di aprile dello stesso anno. attualmente l’unica manifestazione di attività endogena si limita all’emissione di metano in corrispondenza di un canale di drenaggio. abstract: carveni p., benfatto s., maniscalco r., salleo m. & sturiale g., tectonic control on the morfology of the northeastern lower slope of mount etna volcano (sicily). (it issn 0394-3356, 2005). mount etna lies in a structurally highly complex setting, close to the boundary between the malta-hyblean platform and the ionian basin and at the intersection of the malta escarpment and the messina-giardini fault zone. thus, volcanism and tectonics at etna are clearly interacting and exerting a strong control on morphology. the studied area is located on the lower eastern slope of mount etna between capo schisò and macchia stream mouth. the study consisted of stereopairs and cartographic analyses supported by geological and geomorphological surveys. we recognize the system of faults giardini mascali (draws southern of the messina fiumefreddo system), which intersects the low north-eastern slope of the volcanic building of mount etna. it is an active fault systems ne-sw and nne-ssw trending, bounding horsts and grabens which influence river courses and submarine delta deposition. in particular, we analyse the course of alcantara river, which is deviated from its original nw-se trend to a nne-ssw one along a graben. the graben is later filled with lava flow and subsequently the lava fill eroded for rejuvenation of the river due to the uplift of the area. has been hypothesized a succession of tectonic events in the area of the mouths of the alcantara river that has brought to the actual geomorfological framework. from the analysis of earthquakes catalogues, a complete lack of historical seismic events attributable to the activity of the system of faults giardini – mascali is underlined; the attributable seismic events to this system are those related to the reactivation in 1795 december and in 1847 march of the mud volcano known with the name “salsa di fondachello” and to the sinking of the same one, happened in 1847 april. ch4 uprising gas activity is located along a fault with associated seismicity. parole chiave: basso versante nord-orientale dell’etna, tettonica, attività vulcanica, geomorfologia. keywords: low north-eastern slope of mt. etna volcano, tectonics, volcanic activity, geomorfology. il quaternario italian journal of quaternary sciences 18(2), 2005 57-68 1. introduzione il territorio siciliano, come la maggior parte di quello nazionale, è interessato da un’intensa attività tettonica che si manifesta con deformazioni della crosta terrestre; lungo le coste queste possono provocare variazioni relative del livello marino, riconoscibili per l’esistenza di tracce geologiche (depositi di spiaggia sollevati) e/o geomorfologiche (spianate d’erosione marina sollevate, solchi di battente sollevati o sommersi); nell’entroterra i movimenti tettonici si risolvono spesso in scarpate di faglia che condizionano la rete fluviale, dando luogo, nei casi più comuni, a cascate, laghi di sbarramento e fenomeni di cattura. la presente nota si inserisce in una ricerca sulle variazioni geomorfologiche indotte da movimenti tettonici sul basso versante nord-orientale dell'edificio vulcanico etneo; lo studio è basato su rilievi geologici e geomorfologici di dettaglio, sull’analisi di fotografie aeree e della cartografia esistente. in letteratura sono reperibili molti lavori che descrivono le strutture tettoniche affioranti lungo il basso versante orientale etneo; esse assumono una particolare evidenza morfologica nell’area compresa tra sant’alfio a settentrione e acireale a meridione (fig. 2). al contrario, la letteratura è carente nello studio delle adiacenti zone, poste a settentrione, tra mascali e giardini, dove le evidenze morfologiche sono meno chiare. il riconoscimento delle strutture in quest’area è stato reso possibile principalmente attraverso lo studio del reticolo idrografico e della linea di costa. 58 p. carveni et al. 2. quadro geologico dell’area etnea la zona in studio è ubicata nel settore nord-orientale del monte etna, al confine con i monti peloritani. il monte etna, con la sua altitudine di poco superiore a 3.300 metri e un diametro massimo di 44 chilometri, è il più grande vulcano attivo del continente europeo. esso è uno stratovulcano complesso, risultante dalla sovrapposizione di diversi edifici (gemmellaro, 1858; lyell, 1859) poggianti su un basamento in parte alloctono, formato da rocce di età compresa tra il cretaceo ed il pleistocene (cristofolini et al., 1979; romano et al., 1979; lentini, 1982). il bacino del mediterraneo centrale, nel quale si inserisce l’etna, è caratterizzato da differenti domini strutturali, la cui genesi è da inquadrare nel contesto collisionale tra la placca africana e la placca europea; le due masse continentali si scontrano e si saldano tra loro, originando l’orogene appenninico – maghrebide, una catena corrugata che forma la dorsale appenninica e, attraversando l’arco calabro, la sicilia e il canale di sicilia, prosegue lungo le coste nord-africane del maghreb. l’edificio vulcanico etneo sorge al limite tra diversi domini strutturali della sicilia orientale, dove la crosta oceanica ionica e la crosta continentale dell’avampaese ibleo si immergono sotto il fronte dell’orogene appenninico-maghrebide (finetti et al., 1996) (fig. 1). l’avampaese ibleo costituisce il margine della placca africana (burollet et al., 1978), zona considerata stabile verso cui convergono le falde neogeniche dell’orogene appenninico-maghrebide. esso è costituito da una potente successione prevalentemente carbonatica compresa, con lacune stratigrafiche, tra il trias e il pleistocene medio; vi si intercalano prodotti effusivi basici cretacei, miocenici e plio-pleistocenici, la cui risalita è stata favorita da intense fasi tettoniche distensive (cristofolini, 1966; di grande, 1967; 1969; 1972; patacca et al., 1979; carbone et al., 1982 c; lentini et al., 1986; carbone et al., 1987; carveni et al., 1991 a; 1991 b; 1993; carveni & sturiale, 1999). esso confina ad oriente con la crosta oceanica del bacino ionico (finetti, 1982) tramite la scarpata ibleo-maltese, di origine tettonica (finetti & morelli, 1972), originata da un sistema di faglie normali a gradinata, il cui prolungamento verso settentrione interseca il fianco orientale dell’edificio etneo (cristofolini et al., 1979; ghisetti, 1979; lentini, 1982; lo giudice et al., 1982; carbone et al., 1982 a; 1982 b); la scarpata si sarebbe formata in un’unica grande fase tortoniana, con minori riattivazioni posteriormente al deposito degli infrapliocenici trubi, e a luoghi le sono connesse importanti attività vulcaniche (casero et al., 1984). lanzafame & bousquet (1997) ritengono che la scarpata ibleomaltese sia un segmento di un importante sistema di faglie con direzione compresa tra nnw-sse e nw-se, che attraversando la sicilia nord-orientale e il mar tirreno meridionale, raggiunge vulcano, lipari e salina. le unità della catena kabilo-calabride, costituita da falde di basamento cristallino interessate da metamorfismo ercinico con resti dell’originaria copertura sedimentaria meso-cenozoica, sono sovrascorse sulle unità della catena appenninico-maghrebide, in concomitanza dell’apertura del bacino balearico–provenzale e la rotazione del blocco sardo–corso (de jong et al., 1973; dewey et al., 1989). la catena appenninico–maghrebide è costituita da falde sud-vergenti, il cui corrugamento ha interessato, deformandole, le coperture sedimentarie della tetide e dei paleodomini minori ad essa associati, originariamente posti tra il margine della placca europea e il margine della placca africana (finetti et al., 1996). ad iniziare dal pleistocene inferiore intense fasi tettoniche hanno causato un’elevata distorsione al margine settentrionale della placca africana, a causa della differente velocità con cui avviene la subduzione al di sotto della catena appenninico-maghrebide (van bemmelen, 1969; morelli, 1970; selli & fabbri, 1971; giese & morelli, 1975), e ciò ha determinato uno sti-ramento crostale che ha dato luogo a fratture con direzione nwse, ne-sw ed e-w (g hisetti & v ezzani, 1982; scandone, 1982); all’intersezione di tali strutture si è formata una zona di debolezza attraverso la quale avviene la risalita di magmi sub-crustali (frazzetta & villari, 1981). sulla genesi del vulcano e sul quadro strutturale sono stati proposti numerosi modelli: 1) intersezione di importanti lineamenti strutturali come la scarpata ibleo-maltese e l’allineamento messinagiardini (ogniben et al., 1975; mcguire et al., 1997); 2) tettonica estensionale che ha portato alla formazione di un graben nell’area dell’attuale piana di catania (di geronimo et al., 1978); 3) processi di rifting tra il blocco maltese-siciliano e il bacino ionico (gillot et al., 1994, continisio et al., 1997); 4) deformazione al footwall di una faglia normale appartenente al sistema distensivo siculo-calabro ad andamento wnw-ese (monaco et al., 1997); 5) risalita magmatica mantellica causata dalla presenza di un hot spot (tanguy et al., 1997); 6) roll-back di una porzione di litosfera subdotta al di fig. 1 schema strutturale della sicilia (da finetti et al., 1996). ai) avampaese ibleo; cam) catena appenninico-maghrebide; ckc) catena kabilo-calabride; cs) catena sicana; e) edificio vulcanico etneo; sim) scarpata ibleo-maltese; smf) sistema messina – fiumefreddo; il quadrato indicato dalla freccia corrisponde alla zona in studio. structural scheme of sicily (after finetti et al., 1996). ai) iblean foreland; cam) apenninic-maghrebian chain; ckc) kabilocalabrian chain; cs) sicana chain; e) mount etna volcano; sim) hyblean-malta escarpment; smf) fault system messina – fiumefreddo; narrow indicates position of studied area. sotto del mar tirreno (gvirtzman & nur, 1999). l’attività eruttiva dell’etna, inizialmente sottomarina e fissurale, è diventata in seguito subaerea ed a carattere centrale, a causa di un sollevamento regionale, tutt’ora in atto, che ha determinato una variazione nel meccanismo di risalita dei magmi, con conseguente cambiamento del chimismo, da prodotti subalcalini a prodotti più o meno differenziati della serie alcalinosodica, emessi da numerosi apparati eruttivi e raggruppati in quattro unità vulcano-stratigrafiche: centri alcalini antichi, trifoglietto s.l., mongibello antico e mongibello recente (romano, 1982). sulla base di datazioni radiometriche del rapporto k/ar, gillot et al. (1994) hanno distinto quattro periodi di attività dell’etna, ai quali si alternano lunghi periodi di quiescenza: il primo periodo (da 520.000 ± 40.000 a 270.000 anni fa) è caratterizzato da vulcanismo tholeiitico, con fasi eruttive separate da lunghi periodi di quiescenza; il secondo periodo (da 168.000 ± 8.000 a 100.000 anni fa) è evidenziato da un radicale cambiamento del tipo di attività (strato-vulcani al posto di fessure eruttive) e del chimismo dei prodotti (da sub-alcalini ad alcalini); durante il terzo periodo (tra 80.000 e 60.000 anni fa) si formò un grande complesso vulcanico poligenico (unità del trifoglietto); il quarto periodo (da 35.000 anni fa ad oggi) corrisponde allo sviluppo di un grande strato-vulcano, il mongibello; un’importante fase, caratterizzata da eruzioni pliniane e idromagmatiche, permette di suddividere questo periodo in due parti: mongibello antico e mongibello recente. 3. assetto strutturale del versante orientale etneo carapezza (1962), nel tentativo di determinare una relazione tra la tettonica regionale e le zone di minore resistenza dell’etna, identifica un rift lungo il fianco orientale dell’edificio vulcanico. marchesini et al. (1964) riconoscono quattro principali allineamenti tettonici, con direzioni n-s, enewsw, ne-sw e nw-se. frazzetta & romano (1978) identificano due allineamenti alimentatori preferenziali per le aree ad alta probabilità di eruzioni: una nel settore circolare compreso tra ne-sw e ene-wsw, la seconda con direzione nnw-sse. lo giudice et al. (1982) riconoscono nell'area etnea e nelle zone circostanti varie direttrici di faglie: le più importanti hanno direzione n 60° e, n 30° e, n 15° w e n 60° w. kieffer (1983 a; 1983 b) ipotizza scivolamenti gravitativi di parte del versante orientale dell’edificio vulcanico, ed attribuisce il fenomeno alla ripetuta intrusione di magma attraverso un “rift di ne” e un rift meridionale. l’ipotesi di uno scivolamento gravitativo viene ripresa da azzaro et al. (1989) e da neri et al. (1991). borgia et al. (1992), sulla base dei risultati ottenuti da ferrari et al. (1991) sui dicchi affioranti nella valle del bove, ipotizzano uno spreading radiale del substrato dell’etna verso se. lo giudice & rasà (1992) ritengono invece che si tratti di movimenti puramente gravitativi, che provocano lo scivolamento verso sse della porzione dell’edificio 59controllo tettonico ... etneo delimitata a settentrione dalla faglia della pernicana e dal rift di ne, e a se dalle faglie di mascalucia e trecastagni (fig. 2). la documentazione storica sui terremoti avvenuti sul basso versante orientale etneo negli ultimi due secoli e le conseguenze morfologiche dei movimenti tettonici sono analizzate in una serie di articoli (adorni & carveni 1993 a; 1993 b; carveni & bella, 1994; bella et al., 1996; carveni et al., 1996; 1997; gresta et al., 1997). dall’analisi dei sistemi di faglie che nel pleistocene sono stati attivi in sicilia orientale, sulla base di informazioni geologico-strutturali e morfologiche e dell’analisi di sezioni sismiche a mare, monaco & tortorici (1995) e monaco et al. (1995; 1997) distinguono un “sistema acireale – sant’alfio” (faglie normali con componente trascorrente destra nnw-sse) e un “sistema di piedimonte” (faglie normali e fratture d’estensione nne-ssw); entrambi i sistemi, associati ad un’estensione wnw-ese, formano scarpate di età suprapleistocenico-olocenica, le quali esercitano un controllo sulla topografia e sul reticolo idrografico. ricerche basate su rilievi effettuati da satelliti (gironi, 2003) evidenziano un sollevamento in atto di tutta la zona etnea con punte massime di 15 mm/anno, con eccezione del settore circolare delimitato a settentrione dalla faglia della pernicana e sua prosecuzione verso oriente, e a sw dalle faglie di mascalucia e trecastagni: questa zona risulta essere interessata da un fenomeno di abbassamento con un tasso massimo di circa 15 mm/anno a stazzo, frazione di acireale, dove un molo costruito nel 1949 e alto circa 1 metro, attualmente si trova al livello del mare (figg. 2 e 3). 4. lineamenti geologici dell’area l’area in esame è ubicata lungo il margine nordorientale del monte etna, tra la valle del fiume alcantara a settentrione e la foce del torrente macchia a meridione. il substrato dell’etna nell’area studiata è costituito da successioni della catena appenninico–maghrebide, mentre le successioni della catena kabilo–calabride affiorano più a settentrione, fuori dall’area in studio. l’unità strutturalmente più bassa è data da depositi argilloso-arenaceo-conglomeratici alimentati dalle unità cristalline calabridi, noti il letteratura come formazione piedimonte, (fig. 4: 12) di età rupeliana (lentini et al., 2000); essi affiorano lungo il versante destro della valle dell’alcantara. segue il flysch di capo d’orlando (fig. 4: 11), formazione terrigena dell’oligocene superiore–burdigaliano inferiore, il quale poggia in discordanza al tetto delle unità cristalline della catena kabilocalabride, suturandone i relativi contatti tettonici; esso è costituito da facies torbiditiche conglomeratico-arenacee evolventi verso l’alto e lateralmente a facies arenacee o arenaceo-pelitiche; i conglomerati sono stati interpretati da guerrera & wezel (1974) come depositi di base di scarpate che precedono l’arrivo di torbiditi arenacee; la facies arenacea è ben rappresentata lungo la valle del fiume alcantara. in contatto tettonico sul flysch di capo d’orlando affiorano le argille scagliose antisicilidi (fig. 4: 10); 60 fig. 2 ubicazione dell'area in studio, in rapporto alle più importanti strutture tettoniche del versante orientale dell'etna. faglie: fcm) faglia capo schisò – foce del torrente macchia; ff) faglia di fondachello; fg) faglia di giardini; fm) faglia di moscarello; fma) faglia di mascalucia; fms) faglia macchia – stazzo; fn) faglia di naxos; fp) faglia della pernicana; fpvc) faglia praiola – villa calanna; frn) faglia della ripa della naca; frp) faglia della ripa di piscio; fsl) faglia di san leonardello; ft) faglia di trecastagni; ftm) faglia del torrente minisale; sp) sistema di piedimonte. centri abitati: a) acireale; fi) fiumefreddo; fo) fondachello; g) giardini; ma) mascali; m) mascalucia; s) stazzo; sa) sant’alfio; t) trecastagni. cc) cratere centrale; rne) rift di ne. i triangoli indicano zone in cui sono stati misurati sollevamenti e abbassamenti fino a 15 mm/a., (gironi, 2003). location of studied area in the frame of the main tectonic structures of eastern flank of mt. etna volcano: fcm) cape schisò –macchia stream mouth fault; ff)) fondachello fault; fg) giardini fault; fm) moscarello fault; fma) mascalucia fault; fms) macchia – stazzo fault; fn) naxos fault; fp) pernicana fault; fpvc) praiola – villa calanna fault; frn) ripa della naca fault; frp) ripa di piscio fault; fsl) san leonardello fault; ft) trecastagni fault; sp) piedimonte system. towns: a) acireale; fi) fiumefreddo; fo) fondachello; g) giardini; m) mascalucia; ma) mascali; s) stazzo; sa) sant’alfio; t) trecastagni. cc) central crater; rne) ne rift. triangles indicate 15 mm/y uplift or lowering zones up to 15 mm/y (after gironi, 2003). p. carveni et al. 61 ogniben (1960) definì queste argille come complesso sud-liguride, considerandole identiche a quelle del complesso sicilide, ipotizzandone una provenienza dall’area occupata dalle argille variegate del complesso sicilide per fenomeni di “retrocolamento gravitativo” sulla copertura tardorogena del complesso calabride; lentini et al. (1987) attribuiscono alla formazione un’età cretacea. depositi tardo miocenici costituiti da marne argillose grigie con intercalazioni di arenarie (tortoniano) passanti verso l’alto a gessi della serie evaporitica siciliana (messiniano) affiorano in piccoli lembi lungo la valle del fiume alcantara (fig. 4: 9). argille marnose azzurre di età infrapleistocenica (fig. 4: 8) affiorano in un horst allungato in senso nesw a settentrione di fondachello, delimitato a occidente dalla faglia di naxos (fig. 4: b) e a oriente dalla faglia di case decime (fig. 4: g). calcareniti medio-pleistoceniche a briozoi affiorano sui fianchi della collinetta di serra san biagio, a ne di fiumefreddo di sicilia; si tratta di calcareniti giallobrune in banchi di spessore massimo di 2 metri, con spessore in affioramento di circa 30 metri (fig. 4: 7). piroclastiti dell’unità del trifoglietto affiorano nella parte sud-occidentale della zona cartografata (fig. 4: 6). seguono alcune colate laviche provenienti dai centri eruttivi dell’ellittico e del leone (romano, 1982), (fig. 4: 5), colate laviche del mongibello recente, tra le quali riveste una particolare importanza la colata lavica di capo schisò (fig. 4: 4), la colata lavica del 1651 (fig. 4: 3), e la colata lavica del 1928 (fig. 4: 2). alluvioni e depositi di spiaggia attuali (fig. 4: 1) chiudono la serie stratigrafica. 5. dati morfotettonici l’analisi morfologica ha evidenziato l’esistenza di un sistema di faglie dirette, il sistema giardini – mascali (figg. 2, 4 e 5), con sviluppo lineare di quasi 12 chilometri, che dà luogo ad una serie di graben e horst, con direzione ne-sw nella parte più settentrionale, tendente a nne-ssw in quella meridionale. le faglie rigettano formazioni sedimentarie e vulcaniche comprese tra il pleistocene inferiore-medio ed il recente. finora questo sistema di faglie non è stato segnalato in letteratura, malgrado la sua attività abbia esercitato un’intensa influenza sul reticolo idrografico, sull’andamento della linea di costa e presumibilmente su depositi di delta sottomarini; il mancato riconoscimento può essere giustificato dal fatto che la formazione geologica predominante in affioramento è data da alluvioni recenti e attuali, costituite prevalentemente da ghiaie sabbiose, e dal fatto che la zona è intensamente coltivata, per cui eventuali scarpate di faglia vengono velocemente smantellate sia dall’erosione, sia dall’azione antropica. le faglie riconosciute sono: 1) faglia di giardini (figg. 4 e 5: a): direzione n 60° e nel tratto settentrionale, n 35° e in quello meridionale, immersione a se; essa disloca le calcareniti medio-pleistoceniche di serra san biagio, alcune colate laviche attribuite ai centri eruttivi dell’ellittico (romano et al., 1979) e alluvioni recenti; il rigetto verticale in corrispondenza di serra s. biagio è valutabile in almeno 50 metri; 2) faglia di naxos (figg. 4 e 5: b): antitetica alla precedente, ha direzione n 56° e nella sua porzione settentrionale, n 32° e a meridione, immersione a nw; questa faglia disloca argille marnose azzurre inframedio-pleistoceniche pre-etnee e alluvioni recenti. 3) faglia di fondachello (figg. 4 e 5: c): direzione n 35° e, labbro ribassato a nw; essa è evidenziata da un lungo dosso rettilineo che separa la pianura alluvionale dalla spiaggia attuale; è da escludesi che questa scarpata sia una morfologia di tipo eolico, sia in base all’andamento rettilineo presentato, sia in base alla granulometria dei sedimenti, formati da ciottoli e sabbia grossa (amore et al., 1992). 4) faglia capo schisò foce del torrente macchia (figg. 4 e 5: d): con direzione n 45° e nel segmento settentrionale, e n 33° e in quello meridionale, pendenza a se, questa faglia viene ipotizzata in base all’andamento rettilineo della linea di costa e al forte gradiente delle isobate. 5) faglia di case decime (figg. 4 e 5: g): è stata riconosciuta in base a considerazioni stratigrafiche poiché essa mette a contatto le argille quaternarie con le alluvioni recenti; dati inediti relativi a pozzi per uso irriguo evidenziano l’esistenza del substrato argilloso a profondità comprese tra 10 e 15 metri. il sistema giardini – mascali è intersecato lungo la valle del torrente minissale da una faglia normale con componente orizzontale destra e rigetto verticale valutabile in almeno 60 metri (faglia del torrente minissale, figg. 4 e 5: e), e a meridione di fiumefreddo dalla faglia della pernicana, diretta con componente orizzontale sinistra ed attività sismica accertata (figg. 4 e 5: f). la faglia di giardini e la faglia di naxos hanno giocato un ruolo determinante sull’assetto geomorfologico della zona: esse infatti formano il graben capo schisò – mascali, con direzione ne-sw, che ha deviato il tratto terminale del fiume alcantara (fig. 6 a e 6 b); per un certo periodo le alluvioni di questo fiume si sono riversate nella parte meridionale dell’attuale baia di giardini: l’andamento delle isobate in corrispondenza di capo schisò (istituto idrografico della marina, 2001), che corrisponde a questa ipotizzata vecchia foce dell’alcantara, mostra chiaramente l’esistenza di una morfologia attribuibile ad un delta almeno fino a 200 fig. 3 il molo nuovo e il molo vecchio di stazzo. new and old docks in stazzo port. controllo tettonico ... 62 fig. 4 schema geologico: 1) alluvioni e depositi di spiaggia recenti ed attuali; 2) colata lavica del 1928; 3) colata lavica del 1651; 4) colata lavica di capo schisò: αα) tratto nord-orientale; ββ) lobo sud-occidentale; 5) colate laviche dei centri eruttivi dell’ellittico e del leone; 6) piroclastiti dell’unità del trifoglietto; 7) calcareniti medio-pleistoceniche a briozoi; 8) argille marnose azzurre infrapleistoceniche; 9) marne argillose grigie con intercalazioni arenacee (tortoniano) con gessi (messiniano) alla sommità; 10) argille scagliose antisicilidi; 11) flysch di capo d’orlando; 12) formazione piedimonte; a) faglia di giardini; b) faglia di naxos; c) faglia di fondachello; d) faglia capo schisò – foce del torrente macchia; e) faglia del torrente minissale; f) faglia della pernicana; g) faglia di case decime. geological scheme of mt. etna low northeastern slope: 1) present day alluvium and shoreline deposits; 2) 1928 lava flow; 3) 1651 lava flow; 4) capo schisò lava flow: αα) ne flow; ββ) sw bend; 5) lavas from the eruptive centres of ellittico and leone; 6) tephra from the eruptive centres of trifoglietto; 7) middle pleistocene calcarenites with briozoa; 8) lowpleistocene bluish marly clays; 9) grey silty clays with arenaceous intercalations (tortonian) with gypsum (messinian) on the top; 10) antisicilidi varicoloured clays; 11) capo d’orlando flysch; 12 ) piedimonte formation. a) giardini fault; b) naxos fault; c) fondachello fault; d) cape schisò – macchia stream mouth fault; e) minissale stream fault; f) pernicana fault; g) case decime fault. p. carveni et al. 63 fig. 5 schema morfologico: a) faglia di giardini; b) faglia di naxos; c) faglia di fondachello; d) faglia capo schisò – foce del torrente macchia; e) faglia del torrente minis-sale; f) faglia della pernicana; g) faglia di case decime. 1) presunto delta subacqueo del fiume alcantara, formatosi posteriormente alla deviazione tettonica; 2) attuale delta subacqueo del torrente santa venera; 3) presunto vecchio delta subacqueo del torrente santa venera; 4) attuale delta subacqueo del fiume alcantara; 5) presunto vecchio delta subacqueo del fiume alcantara; 6) attuale delta subacqueo del torrente minissale; 7) presunto vecchio delta subacqueo del torrente minissale; 8) delta subacqueo di incerta attribuzione; αα ) tratto della colata lavica che scorrendo lungo il fiume alcantara ha formato capo schisò; ββ) lobo sud-occidentale della colata lavica del fiume alcantara; γγ) deviazione del torrente fiumefreddo causata dalla faglia di naxos; δδ) deviazione del torrente fiumefreddo causata dalla faglia di fondachello; εε) gurna di fondachello; ζζ) acquitrino di anguillara. morphological scheme: a) giardini fault; b) naxos fault; c) fondachello fault; d) cape schisò macchia stream mouth fault; e) minissale stream fault; f) pernicana fault; g) case decime fault. 1) hypothetical alcantara river submarine delta, after tectonin ri-ver piracy; 2) actual santa venera stream delta; 3) hypothetical santa venera stream old delta; 4) alcantara river delta; 5) hypothetical alcantara river old delta; 6) minissale stream delta; 7) hypothetical minissale stream old delta; 8) uncertain attribution delta; αα ) lava flow forming schisò cape; ββ) sw part of lava flow; γγ) stream fiumefreddo deviation caused by naxos fault; δδ) stream fiumefreddo deviation caused by fondachello fault; εε) quagmire gurna di fonda-chello; ζζ ) anguillara quagmire. controllo tettonico ... metri di profondità (fig. 5: 1); l’arrivo di una colata lavica lungo la valle dell’alcantara ha fossilizzato il graben (fig. 6 c), evidenziandolo sia verso ne, dove raggiungendo la costa ha formato la scogliera di capo schisò (figg. 4 e 5: αα), sia verso sw, con l’ampio lobo rivolto in questa direzione, forse in corrispondenza dell’ansa di un meandro preesistente ai movimenti tettonici (figg. 4 e 5: ββ); in seguito l’alcantara ha eroso la colata, andando a sfociare approssimativamente nella stessa zona occupata prima della deviazione di origine tettonica (fig. 6 d): dall’analisi delle carte nautiche (istituto idrografico della marina, 2001) il delta subacqueo relativo all’attuale foce è riconoscibile fino all’isobata –100 metri (fig. 5: 4). oltre a questa importante deviazione del fiume alcantara, la faglia di naxos provoca una deviazione verso ne del torrente fiumefreddo (fig. 5: γγ). l’esistenza della faglia di fondachello era già stata ipotizzata da mercurio (1847), il quale notava che la morfoscultura poteva essere seguita agevolmente dalla spiaggia di riposto a capo schisò; oggi la scarpata di faglia è certamente molto meno evidente, a causa dell’erosione e dell’azione antropica; questa faglia condiziona il tratto terminale del torrente fiumefreddo (fig. 5: δδ) costringendolo a compiere una deviazione verso sw; inoltre, sbarrando alcuni piccoli corsi d’acqua, ha creato le condizioni per la nascita di alcuni stagni costieri: lo stagno conosciuto come gurna di fondachello (fig. 5: εε) (gurna = vasca d’acqua, dal greco moderno γουρνα, giarrizzo, 1989), un secondo stagno che, in base ad alcune carte topografiche del xix secolo si trovava a circa mezzo chilometro di distanza verso sse in località ausini, e del quale non si conservano tracce a causa dell’industrializzazione della zona, e un terzo ancora più a meridione, in contrada anguillara (fig. 5: ζζ). la formazione di uno stagno costiero viene generalmente attribuita all’accumulo di sabbie e/o ghiaie in un tratto di mare poco profondo in corrispondenza di una baia; se l’accumulo evolve da barra subacquea a tombolo, l’insenatura, ormai separata dal mare, si trasforma in lago costiero; la formazione di un tombolo può verificarsi anche lungo una costa rettilinea, se il moto ondoso ha la competenza per spostare ingenti quantità di materiali detritici deposti lungo le foci fluviali o erosi direttamente dal mare lungo la costa. l’analisi della carta nautica dell’area (istituto idrografico della marina, 2001) evidenzia che la profondità del mare aumenta rapidamente con la distanza dalla linea di costa, quindi non è possibile addebitare la formazione dei bacini costieri all’evoluzione da barra subacquea a tombolo; si ipotizza quindi che la genesi della gurna di fondachello e delle zone acquitrinose di ausini e di anguillara sia dovuta all’attività della faglia di fondachello, che ha formato il lungo dosso rettilineo che separa la spiaggia attuale dalla pianura costiera. la faglia capo schisò foce del torrente macchia è stata ipotizzata, principalmente, sulla base dell’andamento rettilineo della linea di costa e del forte gradiente tra le isobate; inoltre, dati di letteratura (monaco & tortorici, 1995) evidenziano la presenza di faglie obliquo-destre appartenenti al sistema messinagiardini, alle quali può essere collegata la faglia qui ipotizzata, la quale presenta identica orientazione e trascorrenza destra; i dati inediti circa l’esistenza del movimento della faglia capo schisò-foce del torrente macchia riguardano l’interazione tra il movimento della faglia in oggetto e l’attuale assetto di alcuni delta subacquei: a) in corrispondenza dell’attuale foce del torrente santa venera si trova una morfologia assimilabile ad un delta subacqueo fino alla profondità di –30 metri (fig. 5: 2); a se di questo ipotizzato delta, se ne trova un altro, riconoscibile fino all’isobata, –200 metri (fig. 5: 3); b) dalla morfologia presentata dalle isobate in corrispondenza dell’attuale foce dell’alcantara si riconosce un delta subacqueo fino all’isobata –100 metri 64 fig. 6 evoluzione morfologica della foce del fiume alcantara. morphological evolution of alcantara river mouth. p. carveni et al. (fig. 5: 4), ed un delta di maggiori dimensioni, fino all’isobata –200 metri, più a se (fig. 5: 5); c) l’attuale delta subacqueo del torrente minissale è rimarcato dall’andamento dell’isobata –20 metri (fig. 5: 6); è riconoscibile un altro delta subacqueo, fino a –200 metri, spostato verso sw di circa 500 metri (fig. 5: 7); d) poco più a sw dell’attuale foce del torrente delle forche è chiaramente riconoscibile un delta subacqueo nella forma dell’isobata –200 (fig. 5: 8); allo stato attuale delle conoscenze non è chiaro quale possa essere il fiume relativo a questa ultima morfologia; si può ipotizzare l’esistenza di un corso d’acqua lungo la cui valle sono scese una o più colate laviche, affioranti nella zona di fiumefreddo, le quali, riempiendo le valli e fossilizzandole, hanno causato la scomparsa dalla superficie dei corsi d’acqua, i quali continuano a scorrere, presumibilmente, in subalveo. 6. la sismicità locale l’analisi dei cataloghi dei terremoti evidenzia una mancanza assoluta di dati relativi alla sismicità locale; le uniche informazioni su sismi avvenuti nella zona in studio, tutti collegati all’attività della salsa di fondachello, ci sono tramandate da mercurio (1847), il quale fornisce le informazioni riassunte nella tabella 1. per quanto riguarda il sisma delle 19,30 del 26 marzo 1847, lo stesso mercurio (1847) avanza dubbi sulla possibilità che l’eruzione di un vulcano di fango, per quanto forte, possa provocare un sisma avvertito ad una distanza di 22 miglia; si ritiene quindi legittimo ipotizzare che si sia trattato di un sisma con ipocentro talmente profondo da avere un campo macrosismico che si estendeva fino a catania, e che l’evoluzione del vulcano di fango sia stata una conseguenza del movimento tellurico. 6. conclusioni sulla base di uno studio a carattere prevalentemente geomorfologico è stato riconosciuto il sistema di faglie giardini – mascali (tratto meridionale del sistema messina – fiumefreddo), il quale interseca il basso versante nord-orientale dell’edificio vulcanico etneo, condizionandone il reticolo idrografico e l’andamento della linea di costa. nell’ambito di un generale sollevamento dell’edificio etneo, le faglie di questo sistema hanno provocato una serie di abbassamenti localizzati, con conseguenti fenomeni di subsidenza, di catture e deviazioni fluviali e di formazione di laghi da sbarramento attualmente in via di estinzione. dall’analisi della morfologia dell’area, si può ipotizzare la seguente successione di eventi tettonici, suddivisa in fasi: 1ª fase: il fiume alcantara scorre, nel suo tratto terminale, lungo una valle di origine tettonica, con direzione nw-se e blocco ribassato a ne (romano et al., 1979) (fig. 6 a); 2ª fase: forse come cedimento causato dal generale sollevamento del territorio, inizia l’attività lungo le faglie del sistema: la faglia di giardini e la faglia di naxos formano un graben lungo il quale viene deviato il fiume alcantara, ed il torrente santa venera diventa suo tributario; si forma un delta subacqueo nell’attuale baia di giardini, riconoscibile dalla forma delle isobate (fig. 6 b); la faglia di fondachello provoca piccole deviazioni fluviali e la formazione di piccoli bacini lacustri (fig. 5: εε e ζζ); 3ª fase: una colata lavica, percorsa la valle dell’alcantara, sbocca in mare formando capo schisò; il fiume alcantara sovralluviona la zona a monte dello sbarramento (fig. 6 c); 4ª fase: a causa del continuo graduale fenomeno di sollevamento della zona, e conseguente ringiovanimento del rilievo e ripresa dell’attività erosiva, il fiume alcantara e il torrente santa venera erodono lo sbarra65 data fenomeni zona di osservazione attività della salsa terremoto disastroso nascita del vulcano di fango, 1693 gen. 11 (xi scala mercalli) sicilia orientale. con emissione di acqua fangosa a 32 metri di altezza. 1795 dic. numerose scosse durante nelle contrade attorno emissione di acqua fangosa tutta la notte, accompagnate alla gurna. fino a 7 metri di altezza. da rombi sotterranei. 1847 mar. 25 scosse nelle contrade attorno alla gurna. ripresa dell’attività. 1847 mar. 26, scosse nelle contrade attorno h 06,15 alla gurna. nessuna 1847 mar. 26, scosse fino a catania. nessuna h 19,30 nelle contrade attorno crollo del fianco orientale 1847 apr. 9 esplosione. alla gurna. del vulcano di fango ed intensa emissione di acqua ricca di gas. controllo tettonico ... mento costituito dalla colata di capo schisò (fig. 6 d); 5ª fase: tutto il sistema giardini – mascali viene dislocato lateralmente dalla faglia del torrente minissale e dalla faglia della pernicana (fig. 5 e, f); 6ª fase: in tempi storici, movimenti tettonici, probabilmente lungo la faglia di fondachello, agevolano la fuoriuscita di gas e fango della salsa di fondachello. in questo contesto non è facile stabilire quale sia stata la fase che ha visto il teorizzato movimento lungo la faglia capo schisò – foce del torrente macchia, con probabile spostamento di circa 500 metri di alcuni delta subacquei, lungo una o più faglie con direzione nnessw e componente orizzontale destra. dall’analisi dei cataloghi dei terremoti si evidenzia una completa mancanza di eventi sismici storici attribuibili all’attività del sistema di faglie giardini mascali; le rare testimonianze di sismicità locale sono relative alla riattivazione nel dicembre del 1795 e nel marzo del 1847 del vulcano di fango conosciuto col nome di salsa di fondachello e allo sprofondamento del medesimo, avvenuto nell’aprile 1847; considerando che il sisma più intenso, avvenuto alle 19,30 del 26 marzo 1847 fu avvertito fino a catania, si può ipotizzare che esso sia imputabile all’attività di una delle faglie facenti parte del sistema giardini – mascali. studio effettuato con i fondi del m.u.r.s.t., nell’ambito della ricerca “morfodinamica di zone vulcaniche e/o sismicamente attive”, responsabile p. carveni. ringraziamenti ringraziamo i referees per gli utili e costruttivi consigli. lavori citati adorni g. & carveni p. 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(1971) tyrrhenian: a pliocene deep sea. rend. cl. fis. mat. nat. accad. lincei, 8, 104-116. tanguy j.c., condomines m. & kieffer g. (1997) evolution of the mount etna magma: constraints on present feeding system and eruptive mechanism. jour. volc. geot. res., 75, 221-250. van bemmelen r.w. (1969) origin of the western mediterra-nean sea . verh. k. -ned. geol. mijnbouwkd. genoot., geol. ser., 26, 13-52. 68 ms. ricevuto il 17 novembre 2004 testo definitivo ricevuto il 22 febbraio 2005 ms. received: november 11, 2004 final text received: february 22, 2005. p. carveni et al. imp.marocco& il sottosuolo del castrum di grado (adriatico settentrionale): studi preliminari per una ricostruzione paleogeografica ruggero marocco1, franca maselli scotti 2, romana melis1 & ennio vio3 1dipartimento di scienze geologiche, ambientali e marine, università di trieste, via e. weiss, 2 34127 trieste. (e-mail: marocco@units.it; melis@units.it) 2soprintendenza per i b.a.a.a.a.a.s. del friuli venezia giulia, p.za libertà, 7, 32100 trieste 3dipartimento di biologia, università degli studi di trieste, via l. giorgeri, 9/10 34127 trieste. riassunto: marocco r., maselli scotti f., melis r. & vio e., il sottosuolo del castrum di grado (adriatico settentrionale): studi preliminari per una ricostruzione paleogeografia. (it issn 0394-3356, 2005). un sondaggio geognostico (12 m di profondità dal p.c.) eseguito sul sagrato della basilica tardo romana di santa maria delle grazie di grado ha permesso di ricostruire l’evoluzione paleogeografia del sottosuolo insulare. emerge che il centro fortificato dell’isola fu costruito (indicativamente a metà del iv sec d.c.) su un cordone litorale sabbioso, formatosi in seguito alla progradazione di un lobo deltizio di un fiume di notevole trasporto solido. l’analisi lito-biostratigrafica dei terreni attraversati attesta la presenza alla base del sondaggio di depositi paralici, che passano progressivamente a sabbie pelitiche di ambiente circalitorale franco, per poi ritornare alla condizione paralica iniziale. la successione descrive così un micro emiciclo trasgressivo-regressivo che si attua totalmente in ambito marino, in brevi lassi temporali e che non ha eguali nel circondario se non nel sottosuolo dell’attuale delta del f. tagliamento. i frammenti di manufatti ceramici individuati da -1,6 a -3,6 m e da -4,6 a -6,2 m di profondità dal l.m.m. attuale fanno supporre l’esistenza di uno scalo o di altre attività antropiche costiere che, almeno nel livello più superficiale, risalgono indicativamente a un periodo compreso tra il i sec. a.c. e il i sec. d.c., subito dopo la fondazione della colonia romana di aquileia (181 a.c.). il secondo orizzonte con resti archeologici, segnalato anche in un altro sondaggio prossimo a quello analizzato, induce a ritenere che anche prima della fondazione della celebre colonia romana l’area gradese fosse frequentata, grazie alla prossimità ad una foce di un fiume navigabile (paleo isonzo?). i risultati conseguiti permettono di ritoccare l’evoluzione costiera dell’area del litorale veneto-friulano fino ad oggi tratteggiata da r. marocco (1991) e di attestare l’importanza dei fiumi e delle loro continue diversioni nella definizione dell'assetto plani-topografico dell’antica linea di costa dell’adriatico nord-orientale. abstract:: marocco r., maselli scotti f., melis r. & vio e., the subsoil of the castrum of grado (northern adriatic sea): a preliminary palaegeographic reconstruction. (it issn 0394-3356, 2005). a 12 m deep exploration well drilled on the church-square of the palaeochristian basilica of santa maria delle grazie in grado allowed a reconstruction of the palaeogeographic evolution of the barrier island. the results indicate that the castrum of the island of grado was built around 4th century ad on the ridge of a prograding delta lobe of a river with intense solid transport. the litho-biostratigraphic analysis of the subsoil testifies to the presence of paralic deposits at the bottom of the well, which gradually pass to muddy sands of fully circumlittoral environment, and back to the original paralic environment. the sequence, in fact, represents a micro transgressiveregressive hemicycle entirely developed in a marine environment and has corresponding events only in the subsoil of the current tagliamento river delta. ceramic fragments recovered from -1,6 m to -3,6 m depth and from -4,6 to -6,2 m depth allow us to suppose the existence of a port or other human coastal activities (villas?) dating back, at least in the top interval, to the 1st century bc 1st century ad, soon after the foundation of the roman colony of aquileia (181 bc). the second interval with archaeological remains, which was discovered also in another well very close to the investigated one, let us believe that the area of grado was settled well prior to the famous roman colony foundation, due to its proximity to the outlet of a navigable river (palaeo isonzo ?). the results obtained from our data highlight a slightly different coastal evolution of the littoral area of veneto and friuli venezia giulia, already described by r. marocco (1991), and testify to the importance of ancient river diversions in reconstructing palaeocoastlines of northeastern adriatic sea parole chiave: : lito-biostratigrafia, ricostruzione paleogeografica, reperti archeologici romani, grado, alto adriatico. keywords: litho-biostratigraphy, palaeogeographic reconstructions, roman archaeological remains, grado, northern adriatic sea. il quaternario italian journal of quaternary sciences 18(2), 2005 135-146 1. introduzione le informazioni sul sottosuolo del castrum di grado e, più in generale, sul territorio ove ora si estende l’importante centro turistico adriatico, sono legate essenzialmente alle stratigrafie dei pozzi per acqua realizzati agli inizi del secolo scorso (tra i primi eseguiti nella bassa pianura veneto-friulana), rendicontate dai più importanti geologi dell’epoca (penk & brückner, 1909; sacco, 1912) e riprese poi da martinis (1953) e comel (1954). più recentemente, altri pozzi per acqua (corredati da stratigrafie generiche) si sono aggiunti ai primi e, oggi, il primo sottosuolo (fino a 10 m di profondità) è documentato da numerose prove penetrometriche statiche e sondaggi meccanici eseguiti a seguito del progressivo sviluppo urbanistico dell’isola. l’insieme di questi dati permette di delineare, con apprezzabile precisione, la litologia e i caratteri geotecnici dei depositi incoerenti che formano il substrato dell’isola, senza però specificare in modo esaustivo la loro genesi. ciò è particolarmente avvertito per il centro storico, che presenta strutture abitative d’epoca romana e chiese paleocristiane, costruite su un cordone di sabbia litorale (il dosso di rena di biagio marin) che poggia su 136 r. marocco et al. depositi d’origine ignota. la conoscenza del sommerso dell’isola, tra l’altro, oltre alla notevole importanza ai fini geoarcheologici, assume estremo interesse paleogeografico anche per completare il quadro evolutivo della formazione della laguna di grado e del suo litorale, tratteggiato da marocco et al. (1984) e da marocco (1991). secondo l’ipotesi formulata da questi autori (desunta dall’analisi di sondaggi stratigrafici eseguiti nei dintorni dell’isola) il territorio si sarebbe formato per trasgressione del mare su una piana alluvionale, a seguito dell’innalzamento eustatico olocenico. anche autori precedenti e soprattutto brambati (1970) erano giunti ad analoga conclusione, essenzialmente sulla base di considerazioni morfologiche dell’assetto costiero (convessità del litorale) e da riscontri sedimentologici sui depositi e sul regime litorale attualmente in atto, arricchite da notizie storiche e archeologiche del territorio, attinte da de grassi (1950; 1952). la possibilità di verificare ulteriormente il quadro paleogeografico prospettato nei lavori precedenti e raffinarlo ulteriormente, colmando la lacuna locale rappresentata dal sottosuolo dell’isola d’oro, ci sono state offerte dalla soprintendenza per i beni a.a.a.a.a e storici del friuli venezia giulia che ha promosso l’analisi di un sondaggio geognostico, effettuato di fronte alla chiesa paleocristiana di santa maria delle grazie, spinto fino a 12 m di profondità dall’attuale piano di calpestio (figg. 1 b e c). 2. litostratigrafia dell’ immediato sottosuolo di grado la gran parte dei sondaggi eseguiti nelle vicinanze del centro storico di grado (dove, per ovvi motivi, le perforazioni nel sottosuolo sono molto rade), mostra una litostratigrafia definita, essenzialmente, da corpi sedimentari sabbiosi, disgiunti da livelli poco potenti di depositi più fini. segnatamente, gli strati di sabbia si rinvengono con una certa regolarità fra 3 e 7, 10 e 11 e 14 e 16 m di profondità dal piano campagna e sono intercalati da peliti più o meno sabbiose. questo abbastanza regolare assetto del substrato sedimentario è puntualmente interrotto in due sondaggi che palesano la presenza di livelli ghiaiosi. il primo (fig. 1b) è ubicato nella piazza duca d’aosta (uno dei primi pozzi per acqua, eseguito nel 1900 e in posizione immediatamente ad occidente del castrum), con la seguente stratigrafia dei primi 10 m (profondità riferite al piano campagna e al l.m.m. attuale quote u.i.m.a., ufficio idrografico del magistrato alle acque; + 1,6 m): piano campagna l.m.m. • 0,0 – 0,9 m +1,6 / + 0,7 m terreno rimaneggiato; • 0,9 – 2,3 m + 0,7 / 0,7 m torba mista a ghiaia; • 2,3 – 5,1 m 0,7 / -3,5 m sabbia fine, grigia; • 5,1 – 5,6 m 3,5 / 4,0 m ghiaia a grossi elementi; • 5,6 – 7,8 m 4,0 / -6,2 m argilla grigiastra mista a sabbia ed a ghiaia con inclusi resti ossei; • 7,8 – 9,0 m 6,2 / -7,4 m ghiaia; • 9,0 10,5 m 7,4 / -8,9 m argilla nerastra più o meno sabbiosa. di questo sondaggio si possiedono anche alcune preziose informazioni bio-stratigrafiche riferite da comel (1954): a 7,8 m (-6,2 m dal l.m.m.) si rinvenne il primo rappresentante della fauna marina (cerithiopsis), mentre a 10,5 m (-8,9 dal l.m.m.) furono ritrovati piccoli bivalvi a guscio sottile (loripes lactea) e cardium insieme a frammenti di gasteropodi (cerithium, cerithiopsis). più a settentrione, a poche centinaia di metri dall’estremità nord del centro fortificato si colloca il pozzo dell’ospedale, che manifesta ancora livelli di ghiaia nella seguente stratigrafia (sempre riferita al p.c. e al l.m.m. + 1,4 m; collocazione planimetrica in fig. 1b): piano campagna l.m.m. • 0,0 – 6,0 m +1,4 / -4,6 m terreno rimaneggiato, in prevalenza sabbioso, con resti di gusci di molluschi marini; • 6,0 – 6,5 m -4,6 / -5,1 m ghiaia mista a sabbia; • 6,5 – 9,0 m -5,1 / -7,6 m argilla torbosa; • 9,0 – 11,0 m -7,6 / -9,6 m sabbia con abbondanti frammenti di conchiglie. di là dalla variazione delle litologie presenti (da torbe a ghiaie) che palesano (se autoctone) una deposizione in ambienti con bruschi salti d’energia, rimane d’eccezionale importanza la presenza dei livelli ghiaiosi che risultano porsi in posizione più meridionale e meno profonda dell’intera area lagunare e in possibile continuità di sedimentazione con gli analoghi depositi rinvenuti a est di aquileia (paleoalvei del torre-natisone e isonzo; fassetta et al., 2003). in termini molto stringati, ammessa l’autoctonia delle ghiaie (che non è stato possibile analizzare), queste dovrebbero essere state deposte da un corso d’acqua di notevole trasporto solido. l’ipotesi dell’origine e della deposizione fluviale di questi sedimenti sembra essere suffragata da più indizi, tra cui la loro continuità in due sondaggi (posti a circa 300 m di distanza), e soprattutto dalla successione stratigrafica della terebrazione di piazza duca d’aosta. qui, a un deposito lagunare-litorale (con faune tipiche) succedono episodi di sedimentazione a ghiaie, intercalati da sedimenti “sporchi” (pelite, sabbia e ghiaia mescolate insieme), con una sequenza caratteristica di alveo fluviale in fase di occlusione o avulsione. l’unico sondaggio eseguito all’interno del castrum (a sud del campanile; quota 1,7 m dal l.m.m.; fig. 1b) mostra, dopo ca. 3,5 m di sabbia e ghiaia con ciottoli e frammenti di cotto (riporto), sabbie medio-fini di colore grigio con frammenti conchigliari (da -1,8 a 5,3 m), poi sabbie debolmente limose, grigie, sempre con gusci rotti e minuti pezzi di cotto (da -5,3 a -9,3 m), alternanze di limi e sabbie fini, grigie (fino a -12,3 m) e, infine, sabbie medio-grosse, sempre grigie (da -12,3 a 15,3 m; comune di grado, 1995). al di fuori dell’abitato insulare (a ca. 2 km a occidente), alle spalle del banco dei tratáuri (s12 in marocco et al., 1984; fig. 1a), è stata appurata la contiguità dei terreni del sottosuolo con un corso fluviale capace di trasportare ghiaie. dall’analisi del sondaggio emerge una sequenza definita da peliti (-13,9 / -10,9 m), chiuse al tetto da sabbie medie, laminate (ambiente di sedimentazione continentale, posto in relativa vicinanza di un ambiente deltizio), seguite da un intervallo di sedimenti pelitici bioturbati (9,9 / -6,5 m) con all’interno dispersi ciottoli di rocce calcaree (di ambiente deltizio-lagunare) e da peliti con ciottoli di fango più 137ricostruzione paleogeografica ... fig. 1 il territorio della laguna e dell’isola di grado (adriatico settentrionale). a) ubicazione dei sondaggi s11 e s12. b) sondaggi stratigrafici eseguiti in prossimità del castrum (area in rigato): 1. s.m. delle grazie; 2. p.za duca d’aosta; 3. ospedale; 4. campanile; 5. torre quadrata del castrum. c) sezione trasversale della chiesa di s.m. delle grazie (la freccia indica l’ubicazione del sondaggio sul sagrato). the lagoon and the island of grado (northern adriatic sea). a) location of the wells s11 and s12. b) stratigraphic wells (1 to 5) drilled around the castrum (black lines): 1. ancient basilica of santa maria delle grazie; 2. piazza duca d’aosta; 3. hospital; 4. bell-tower; 5. square tower of the castrum. c) transversal section of the church of santa maria delle grazie (the projection of the well on the churchsquare is indicated by the arrow). a b c 138 specificatamente lagunari, troncate al tetto da una superficie erosionale. sopra questa superficie si depongono sabbie litorali e peliti sabbiose di retrobanco (situazione attuale). più a nord (sondaggio s11, fig. 1a) in un’isola della laguna di grado si sono rinvenuti 30 m di depositi continentali (totalità del sondaggio), erosi a 6,0 m di profondità da sabbie fluviali. questi dati portano a ritenere che ad occidente del castrum (ritenuto costruito nella seconda metà del iv sec. d.c.; cuscito, 1969) dovesse scorrere un fiume di notevole trasporto solido che, in seguito, si spostò verso oriente fino a lambire la costituenda città fortificata. ciò spiegherebbe alcuni problemi molto ribattuti, ma sostanzialmente ancora aperti, circa l’antico abitato di grado (vedi mirabella roberti, 1974-75; marchesan & marocco, 1994). secondo le ricostruzioni paleogegrafiche fino ad oggi prodotte, l’orientazione nw-se del castrum mal si combina con le direzioni delle presunte linee di riva dell’epoca (grossomodo e-w) e un centro fortificato in riva al mare di solito si allinea alla costa. un altro indizio, poi, viene suggerito dalla forma planimetrica del centro fortificato: la configurazione stretta ed allungata con dimensioni a trapezio (320 x 48-80 m), si adatta bene ad un lembo di terra proteso o falcato verso mare, come le sponde di un delta digitato. 3. il sondaggio della chiesa di s. maria delle grazie santa maria delle grazie (16,8 x 11,5 m; fig. 1c) è una delle più importanti chiese paleocristiane dell’italia settentrionale. edificata probabilmente alla metà del sec. v, fu restaurata e sopraelevata (di circa 1,1 m) dal patriarca elia (571-586 d.c.). anche se rinnovata più volte (gli ultimi lavori risalgono al 1920 e poi al ‘57), presenta un notevole degrado sia nelle opere murarie sia nelle strutture interne, tanto da richiedere urgentemente un ulteriore intervento di consolidamento e restauro. nell’ambito delle indagini odierne si sono eseguiti più sondaggi verticali a carotaggio continuo, di cui uno a raggiungere la profondità di 12 m dal piano piazzale (+1,4 m dal l.m.m; quota u.i.m.a.). le carote estratte (di cui si possiede una prima descrizione di cantiere) sono state ridefinite in termini lito-biostratigrafici, quindi campionate per la definizione dei caratteri sedimen-tologici, biologici e archeologici del sottosuolo. in sintesi, i depositi sotto l’anteportico della chiesa sono costituiti da sabbie mescolate in diverse proporzioni a peliti (classificazione di nota, 1958) e a ghiaie (riporto). sono presenti, inoltre, una variegata frazione archeologica costituita da frammenti di mattoni, laterizi e di intonaci e una componente organogena, definita da gusci di molluschi (malacofauna), di foraminiferi e di ostracodi (microfauna). 3.1 litostratigrafia prendendo in considerazione la sola frazione granulometrica priva delle ghiaie (depositi con ø < 2000 µm) si osserva nei campioni di sedimento una netta polimodalità, con picchi principali nel campo delle sabbie e secondari in quello delle peliti (fig. 2). segnatamente, dal basso verso l’alto si riconosce una prima “unità” (informale) litostratigrafica (da -10,6 a 4,5 m dal l.m.m.), definita da una sequenza costituita da pelite molto sabbiosa, con contenuti di sabbie e pelite altalenanti che passa poi gradualmente, a circa -6,0 m, a sabbia pelitica, facendo assumere all’unità un tipico motivo deposizionale a energia crescente o negativo (coarsening upward). la sequenza è chiusa al tetto da un contatto netto planare. segue una seconda “unità” (da -4,5 a -0,3 m), caratterizzata sempre da pelite molto sabbiosa che diviene via, via più sabbiosa (sabbia pelitica) sempre con un motivo negativo. verso l’alto tra la sabbia pelitica si rinvengono resti di murature e quindi, attraverso un passaggio graduale, depositi più fini. la sommità della seconda “unità” è interrotta da uno scavo (testimoniato da un contatto netto, irregolare) riempito da materiale di riporto (“terza unità”, da -0,3 a +1,4 m). nell’insieme la frazione sabbiosa del sondaggio mostra, dal basso verso l’alto, dopo una fase altalenante, da -6,0 m di profondità una chiara tendenza all’aumento delle dimensioni medie dei granuli che segnala un graduale incremento dell’energia di trasporto dell’ambiente, anche se rimane in termini assoluti ad un livello relativamente basso (classazione moderata). il confronto di alcuni parametri statistici elementari (mz δi; folk & ward, 1957; fig. 3) dei depositi attraversati dal sondaggio con quelli dei sedimenti della spiaggia di grado, del litorale più prossimo a questa località e con le sabbie di piattaforma che caratterizzano i fondali centrali del golfo di trieste, mostra diversità significative che in altri lavori sono state attribuite a una genesi fluviale (gordini et al., 2002). in sostanza, sedimenti con caratteri analoghi a quelli del sottosuolo della chiesa gradese si rinvengono solamente in vicinanza di foci fluviali protette (attuale situazione dei fondali del delta dell’isonzo alla profondità -5 m) o alla bocca della laguna di grado (ancora profondità -5 m). in entrambi questi bracci di mare l’idrodinamismo ambientale viene determinato da correnti di trasporto fluviale o mareale che coesistono con l’energia di classazione del moto ondoso. ad analoga conclusione si arriva anche applicando il diagramma c-m di passega (1964) (fig. 4). l’elevata dimensione del parametro c rispetto ai diversi valori di m segnala l’esistenza di due famiglie di sedimenti: una a, costituita da depositi che si muovono essenzialmente per sospensione, ed una b, ove si mescolano sedimenti trasportati al limite tra sospensione e saltazione. nella prima area trovano spazio i depositi ubicati al letto e quelli al tetto del sondaggio, prima della superficie d’erosione antropica; nella seconda, tutti i rimanenti. 3.2 biostratigrafia l’analisi delle malacofaune è stata eseguita sulla frazione >2000 µm di tutti i campioni di sedimento prelevato; quella quali-quantitativa sulle microfauna, invece, sulla sola frazione sabbiosa (2000 ÷ 50 µm) dei campioni, escludendo quelli sommitali, chiara-mente rimaneggiati. 3.2.1 malacofaune lo scarso detrito conchigliare rinvenuto nel sondaggio ha messo in risalto: • la presenza di fibre vegetali che indicano una copertura dei fondali marini ad opera di praterie di fanerogame (alla sommità del sondaggio, -0,6 m, e al letto, -10,6 m); • la presenza da -3,5 m a -7,8 m di bittium reticulatum, r. marocco et al. 139 fig. 2 log stratigrafico e curve di frequenza dei depositi del sondaggio di s.m. delle grazie. stratigraphic log and grain-size frequency distributions of the deposits drilled by the well of s. maria delle grazie. ricostruzione paleogeografica ... 140 indicatore della biocenosi ad alghe fotofile che attualmente, in alto adriatico, si insediano da 3 a 6 m di profondità; • la comparsa di donax trunculus (a -0,6 e a -3,5 m), che è una specie componente la biocenosi delle sabbie fini ben calibrate (peres & picard, 1964), insieme a gibbula leucophaea, jujubinus striatus, rissoina bruguierei, triconia, cerithium vulgatum, aequipecten opercularis, lentidium mediterraneum (presenti in forma discontinua da -3,5 m di profondità, al letto del sondaggio) che indicano chiaramente un ambiente marino di acque basse; • alla associazione con le specie sopra elencate di loripes lacteus (da -3,5 a -7,8 m di profondità), lucinella divaricata (-6,6 m), chamelea gallina (-7,8 m), ostrea sp, che sono indicatori di un ambiente costiero riparato; • rari frammenti di glycymeris sp e di veneridae che suggeriscono la provenienza delle faune da sabbie costiere. in sintesi, seguendo lo schema di peres & picard (1964), la fauna a molluschi individuata nel sottosuolo della chiesa è rappresentativa della biocenosi delle sabbie costiere poste in prossimità di una bocca lagunare o di una foce fluviale. altre analisi malacologiche condotte su un unico campione di sedimento prelevato sotto la torre quadrata del castrum (piazza della corte, oggi b. marin; vedi fig. 1b, sondaggio 5), hanno evidenziato un’associazione tassonomica costituita da chamelea gallina, loripes lacteus, plagiocardium papillosum, divaricella divaricata, chama gryphoides, lentidium mediterraneum, donax sp (cfr d. semistriatus), glycymeris sp., bittium reticulatum e auriculinella bidentata. tutte queste specie sono tipicamente litorali (piano infralitorale) e costituiscono la biocenosi delle “sabbie fini di modo calmo” (peres & picard, 1964), rappresentativa dell’epifauna delle fanerogame (vedi bittium) e dell’endofauna del sedimento sciolto. a questa associazione si aggiunge auriculinella, un gasteropode polmonato che vive nel piano sopralitorale sabbioso e lentidium (indicativo della biocenosi delle sabbie fini superficiali) che segnala un dinamismo più marcato del fondo marino rispetto alle prime. nel complesso, l’associazione malacologia è quella tipica delle forme “spiaggiate”, dove l’unica specie in posizione fisiologica è data dal gasteropode polmonato. le faune presenti, anche se più numerose rispetto a quelle rinvenute nel sondaggio, portano a ritenere che i depositi sotto la chiesa e sotto il castrum siano molto simili e rappresentativi delle condizioni ambientali dell’attuale litorale di fronte a grado. 3.2.2 microfaune a) foraminiferi nei campioni di sedimento della carota sono presenti 48 specie di foraminiferi bentonici, appartenenti a 17 generi (tab. 1), con prevalenza di miliolina (27 specie) su rotaliina (21 specie). quattro specie sono state mantenute in nomenclatura aperta. in generale, si registra una diminuzione della ricchezza specifica spostandosi dalla parte centrale del sondaggio verso le estremità. più in particolare, alla base della perforazione (-10,6 m) si riscontra una limitata presenza di specie che aumenta soprattutto da -9,2 m di profondità e si mantiene più o meno costante fino a -4,7 m. dal successivo livello fino alla superficie del sondaggio il numero delle specie diminuisce drasticamente. per quanto riguarda il numero d’individui per specie, normalizzato in percentuale, si ritrova una netta predominanza di rotaliina, con percentuali di presenza che variano da 52% a 100%. i miliolina, sebbene presenti con un numero maggiore di specie, sono numericamente inferiori, con percentuali dei gusci variabili fino a 47,5%. inoltre, spostandosi dalla base del sondaggio verso la parte più superficiale, assistiamo ad una diminuzione, non solo della ricchezza specifica, ma anche del numero degli individui/grammo (tab. 1). fig. 3 diagramma mz-σi relativo ai sedimenti del sondaggio di s.m. delle grazie, messi a confronto con le sabbie di spiaggia, i depositi del litorale di grado e con le sabbie di piattaforma del golfo di trieste. mz vs. σi diagram of the sediments from the exploration well of s. maria delle grazie, compared with grado beach sands (squares) and littoral sediments (triangles), and sands from the continental shelf of the gulf of trieste (crosses). fig. 4 diagramma c-m dei depositi del sottosuolo della chiesa di s.m. delle grazie. campo a: trasporto per sospensione; campo b: trasporto per saltazione-sospensione. c-m diagram of the deposits from the subsoil of s. maria delle grazie. a: suspension transport field; b: saltation-suspension transport field. r. marocco et al. 141 tab. 1 frequenza percentuale dei foraminiferi rinvenuti nel sondaggio di s.m. delle grazie; gli asterischi indicano i taxa tipicamente paralici. distribution of foraminifers collected in the s. maria delle grazie borehole (in %); paralic taxa are indicated by an asterisk. specie prof. (m): 10.6 9.2 7.8 6.6 4.7 3.8 3.5 2.5 1.6 0.9 0.6 adelosina carinata-striata 0.0 1.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 adelosina dubia 0.0 0.0 0.4 1.9 1.4 0.0 2.5 0.0 0.0 0.0 0.0 adelosina elegans 0.0 0.0 0.0 0.0 0.9 3.4 0.0 0.0 0.0 0.0 0.0 adelosina ferussacii 0.0 0.0 0.4 1.9 3.2 0.0 0.0 0.0 0.0 0.0 0.0 adelosina longirostra 0.0 5.1 3.0 9.3 3.2 0.0 2.5 0.0 0.0 0.0 0.0 ammonia beccarii 24.1 7.0 24.6 6.0 15.4 13.8 15.0 46.2 53.8 0.0 5.0 ammonia inflata 41.0 5.1 7.5 12.6 14.9 3.4 22.5 7.7 15.4 0.0 40.0 ammonia papillosa 9.6 0.0 15.7 7.0 10.9 48.3 20.0 0.0 23.1 33.3 0.0 ammonia parkinsoniana 0.0 0.0 8.2 6.5 5.0 6.9 7.5 23.1 0.0 0.0 0.0 ammonia tepida* 6.0 9.5 0.7 2.8 0.9 0.0 0.0 0.0 0.0 0.0 35.0 aubignyna perlucida* 4.8 5.1 0.0 0.0 2.7 0.0 0.0 0.0 0.0 0.0 0.0 buccella granulata 2.4 0.0 1.1 1.4 2.3 3.4 2.5 0.0 0.0 0.0 0.0 cribroelphidium granosum* 8.4 3.8 2.6 5.1 1.8 0.0 0.0 0.0 0.0 0.0 0.0 cycloforina villafranca 0.0 0.0 2.2 3.7 3.6 0.0 0.0 0.0 0.0 0.0 0.0 discorbis sp. 0.0 3.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 elphidium aculeatum 0.0 0.0 0.7 0.5 0.9 0.0 0.0 0.0 0.0 0.0 0.0 elphidium gerthi 0.0 3.2 0.7 1.9 0.5 0.0 0.0 0.0 0.0 0.0 0.0 elphidium incertum 0.0 2.5 0.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 elphidium jenseni 0.0 0.0 0.4 1.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 elphidium macellum 2.4 0.0 2.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 elphidium maioricense 0.0 3.2 1.9 5.1 5.4 3.4 2.5 7.7 7.7 0.0 0.0 massilina gualtieriana 0.0 0.0 1.5 0.9 1.8 0.0 0.0 0.0 0.0 0.0 0.0 massilina secans 0.0 0.0 0.7 1.4 1.4 0.0 0.0 0.0 0.0 0.0 0.0 neoconorbina terquemi 0.0 0.6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 nonion depressulum 0.0 4.4 0.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 nonion pauciloculum* 0.0 5.1 0.0 0.5 0.5 0.0 0.0 0.0 0.0 33.3 20.0 polymorphina sp. 0.0 0.0 1.9 2.8 0.5 0.0 7.5 7.7 0.0 0.0 0.0 quinqueloculina berthelotiana 0.0 0.6 0.0 0.0 0.5 0.0 0.0 0.0 0.0 0.0 0.0 quinqueloculina jugosa 0.0 0.0 1.1 1.9 1.4 0.0 0.0 0.0 0.0 0.0 0.0 quinqueloculina lata 0.0 0.0 0.7 1.4 1.8 0.0 0.0 0.0 0.0 0.0 0.0 quinqueloculina milletti 0.0 1.9 1.1 1.4 0.5 0.0 0.0 0.0 0.0 0.0 0.0 quinqueloculina parvula 0.0 1.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 quinqueloculina pygmaea 0.0 0.0 0.4 0.9 1.4 0.0 0.0 0.0 0.0 0.0 0.0 quinqueloculina seminulum 0.0 10.1 0.4 0.0 0.9 6.9 0.0 7.7 0.0 16.7 0.0 quinqueloculina sp. 1 0.0 1.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 quinqueloculina stelligera 0.0 10.1 0.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 quinqueloculina vulgaris 0.0 0.0 0.4 0.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 rosalina bradyi 0.0 0.0 0.4 0.5 0.5 0.0 0.0 0.0 0.0 0.0 0.0 rosalina obtusa 0.0 0.0 0.0 0.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 sigmoilina costata 0.0 1.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 siphonaperta agglutinans 0.0 0.0 0.4 0.0 0.9 3.4 7.5 0.0 0.0 16.7 0.0 siphonaperta aspera 0.0 0.0 11.6 12.1 10.4 3.4 7.5 0.0 0.0 0.0 0.0 spiroloculina sp. 0.0 0.0 0.4 0.0 0.5 0.0 0.0 0.0 0.0 0.0 0.0 triloculina marioni 1.2 1.3 0.7 1.9 0.9 0.0 0.0 0.0 0.0 0.0 0.0 triloculina schreiberiana 0.0 0.0 3.0 3.7 2.7 3.4 2.5 0.0 0.0 0.0 0.0 triloculina tricarinata 0.0 0.0 0.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 triloculina trigonula 0.0 11.4 1.5 1.9 0.9 0.0 0.0 0.0 0.0 0.0 0.0 si g la c a m p io n e 1 0 ( 9 5 -9 8 ) 1 0 ( 0 8 -1 0 ) 9 ( 4 0 -4 4 ) 8 ( 3 5 -3 8 ) 7 ( 2 0 -2 4 ) 6 ( 2 0 -2 4 ) 5 ( 7 4 -7 9 ) 4 ( 7 5 -8 0 ) 3 ( 2 7 -3 0 ) 3 ( 8 8 -9 0 ) 2 ( 8 7 -8 9 ) totale individui : 83 158 268 215 221 29 40 13 13 6 20 gusci/peso frazione sabbiosa : 14.3 27.9 39.3 25.4 53.8 4.2 4.7 1.3 1.0 0.5 3.2 ricchezza specifica : 9 23 36 30 33 11 12 6 4 4 4 ricostruzione paleogeografica ... i principali taxa rinvenuti in percentuale sono ammonia beccarii, a. inflata, a. papillosa, a. tepida, nonion pauciloculum, elphidium maioricense, quinqueloculina agglutinata, q. seminulum e siphonaperta aspera. segnatamente a. beccarii, a. inflata e a. papillosa sono presenti quasi costantemente lungo tutto il sondaggio, mentre gli altri si rinvengono in modo variabile lungo la colonna stratigrafica. la maggior parte dei taxa rinvenuti sono caratteristici del piano marino infralitorale come adelosina carinata-striata, a. dubia, a. ferrusacii, elpfidium spp., quinqueloculina jugosa, q. milletti, q. stelligera, q. vulgaris e triloculina trigonula. molte di queste specie possono vivere in substrati vegetati: buccella granulata (principalmente su cymodocea), elphidium aculeatum, e. jenseni, e. macellum (in foglie di cymodocea e posidonia), e. maioricense (su posídonia), massilina secans, rosalina bradyi (su posidonia), r. obtusa, quinqueloculina lata, triloculina marioni e t. trigonula. alcune specie fra quelle rinvenute, oltre che nel piano infralitorale, sono segnalate anche in quello circalitorale superiore, come adelosina elegans, ammonia beccarii, a. papillosa, a. inflata, cycloforina villafranca, elphidium incertum, sigmoilinita costata e triloculina marioni (cimerman & langer, 1991; sgarrella & moncharmont zei, 1993; fiorini & vaiani, 2001). alcune specie, inoltre, sono vincolate da particolari tipi di substrato: adelosína elegans e cycloforina villafranca a detrito; siphonaperta aspera ed elphidium incertum a sabbie fini; buccella granulata ed elphìdium macellum a sabbie fini con copertura vegetale; ammonia parkinsoniana e a. beccarii a sabbie; ammonia papillosa a sabbia e detrito fangosi; cribroelphidium granosum a sabbia fine e fango. importante è segnalare che diversi taxa rinvenuti nel sondaggio sono tipicamente caratteristici degli ambienti paralici lagunari, come ammonia parkinsoniana, a. tepida, aubignyna perlucida, cribroelphidium granosum e nonion pauciloculum e, in minor misura, adelosina elegans e quinqueloculina seminulum. da un punto di vista quantitativo, nel sondaggio indagato si osserva una netta dominanza delle specie tipicamente marine, in particolar modo nei livelli centrali (da -4,7 a -1,6 m), dove queste raggiungono anche valori del 100%. nella parte basale e in quella più superficiale, viceversa, aumenta la presenza percentuale delle specie tipicamente paralico-lagunari (tab. 1 e fig. 5). dall'analisi qualitativa e quantitativa dei foraminiferi riscontrati lungo la carota in esame è possibile quindi ipotizzare la sequenza dei paleoambienti che si sono avvicendati nel sottosuolo della chiesa di santa maria delle grazie. dal basso verso l'alto, questa si può così riassumere: • parte basale della carota (intervallo -10,6 / -9,2 m) che rappresenta un ambiente di dominio marino infralitorale con influenze d’acque più dolci o salmastre, testimoniate da una discreta percentuale di specie caratteristiche quali aubignyna perlucida, cribroelphidium granosum e nonion pauciloculum. oltre a queste si riscontrano anche rappresentanti dei taxa comunemente rinvenuti anche nei livelli sovrastanti (es. ammonia spp.) e specie in grado di tollerare condizioni di salinità variabile (es. quinqueloculina seminulum e q. stelligera) (amorosi et al., 1999). si tratta, presumibilmente, di un ambiente marino costiero poco profondo, come testimoninato dalla buona presenza di ammonia beccarii soprattutto nel livello di base. la scarsa diversificazione specifica è probabilmente imputabile all'instabilità ambientale data dall’ingresso d’acque a minor salinità; • nei livelli superiori, tra -7,8 m e -4,7 m di profondità, si registra un’evoluzione verso un dominio più francamente marino. la presenza di specie paraliche è inferiore rispetto al livello sottostante, mentre dominano le forme legate ad ambiente marino infralitorale, soprattutto definite da rappresentanti del genere ammonia e da miliolidae, qui particolarmente diversificate; rimane però la testimonianza di una leggera influenza da parte d’acque dolci. si può pensare si tratti di un ambiente anche a discreto idrodinamismo, soprattutto date le dimensioni e lo spessore di molti gusci, in particolare di adelosina longirostra e ammonia spp. sono molto diffusi anche i foraminiferi tipicamente epifiti: ciò potrebbe testimoniare anche la presenza di una copertura vegetale. l’associazione 142 fig. 5 andamento della frequenza percentuale dei principali gruppi di foraminiferi con la profondità nel sondaggio della chiesa di s.m. delle grazie. per ammonia spp. (costiere) si intende la somma percentuale di a. beccarii, a. inflata e a. papillosa. main foraminifer groups frequency log (%) in the s. maria delle grazie borehole. ammonia spp. indicates the percent sum of a. beccarii, a. inflata e a. papillosa. r. marocco et al. rinvenuta bene si confronta con l’associazione md definita da amorosi et al. (2004) nell’ambito dello studio paleoambientale del delta del fiume po. • dalla profondità di -3,8 m si assiste, come già precedentemente descritto, ad una diminuzione sia del numero delle specie sia degli individui presenti. drasticamente ridotta è anche la quantità degli epifiti. l'ambiente è ancora marino, ma mostra ancora una certa instabilità. il forte aumento percentuale di ammonia beccarii, a. inflata e a. papillosa, indicano ambienti molto costieri, con paleoprofondità valutabili nell’ordine di pochi metri, come suggerito da sgarrella & moncharmont-zei (1993). • la situazione muta nei livelli più superficiali (da -0,9 a -0,6 m), in quanto si ritorna ad una situazione simile a quella descritta per i livelli più profondi, in quanto aumenta nuovamente la componente paralica (anche se costituita esclusivamente da ammonia tepida e nonion pauciteoculum) e sono del tutto assenti i foraminiferi porcellanacei. il deposito costituito da sabbie scarsamente organogene, dove il contenuto di gusci varia da 0.5 a 3.2 individui/grammo, rende comunque difficile un'interpretazione certa, sebbene si sia propensi a interpretarlo come un ambiente spostato verso una spiaggia. probabilmente le forme presenti sono state oggetto di trasporto eolico o di episodi di mareggiata. b) ostracodi l’analisi qualitativa eseguita sulle ostracofaune presenti nel sondaggio ha permesso di distinguere i seguenti intervalli: • la base del sondaggio (-10,6 / -7,8 m) presenta una buona percentuale (circa 40%) di individui giovani e adulti di pontocytere turbida e rarissimi individui di loxoconcha ovulata, leptocythere sp. e cythereis sp., che generalmente vivono in ambiente infralitorale (montenegro et al., 1998; amorosi et al., 1999); • una parte centro-finale del sondaggio (da -6,6 a -1,6 m), con un intermedio di assenza di forme (da -4,7 a 3,8), dove si riscontrano sempre esemplari adulti di specie più specificatamente marine (semicytherura incongruens e neocytherideis fasciata, loxoconcha ovulata e pontocytere turbida) con una certa influenza d’acque salmastre, segnalata da cyprideis torosa; • la parte finale del sondaggio (da -1,6 a -0,6 m) con la sola presenza di cytheretta adriatica e loxoconcha ovulata, di ambiente infralitorale. in buona sostanza le ostracofaune confermano quanto appurato dalle precedenti indicazioni sedimentologiche e biostratigrafiche e cioè la presenza nel sottosuolo di grado di ambienti sedimentari tipicamente marini (infralitorali e marino franco) con una leggera influenza di acque salmastre imputabili alla vicinanza di un delta fluviale o di una bocca lagunare. 3.3 la componente archeologica dei sedimenti nel sondaggio sono presenti diffusi minuti frammenti di laterizi arrotondati, frammisti a scaglie calcaree, mattoni e pezzi d’intonaco fino a circa -6,0 m di profondità. i resti archeologici sono abbondanti nei primi metri (fino a -2,6 m dal l.m.m.) e poi diminuiscono in modo consistente procedendo verso il letto, rimanendo comunque presenti come frazione minoritaria del sedimento fino alla profondità indicata. in particolare, a -1,0 / -1,1 m dal l.m.m. si rinvengono un pezzo di mattone carotato dalla perforazione e grossi frammenti di cotto e d’anfora, insieme a scaglie di calcare grigio, con intonaci misti a sabbia. il tutto sembra indicare un livello antropico che potrebbe essere indicativo di resti di muretti a secco o di fondazioni. a circa -2,2 m, invece, sono presenti, ben inglobati nel sedimento, laterizi, pezzi di una piccola ciotola (i sec. a.c. ÷ i sec. d.c.) e frammenti di intonaco. questi dovrebbero rappresentare le prime testimonianze di un insediamento romano (ostium) nel territorio gradese (foto 1). anche in almeno tre metri di carota sotto questo livello si rinvengono rari frammenti minuti di laterizi, arrotondati e ben omogeneizzati nel sedimento sabbioso. analoga situazione è stata segnalata anche più a sud nel sondaggio del campanile (comune di grado,1995). al momento non sono disponibili datazioni radiometriche su questi depositi che, vista sia la tipologia di prelievo (carotaggio a secco con rivestimento del foro), sia l’appurata differenza granulometrica dei sedimenti e dei detriti antropici rispetto ai depositi superiori, sono da ritenersi in situ. la profondità di rinvenimento e l’ambiente marino dei sedimenti che li inglobano fanno ritenere che questi siano precedenti alla fondazione della colonia romana d’aquileia (181 a.c.) e risalenti, indicativamente, al periodo veneto. da registrare che questi tritumi si ritrovano specialmente nei depositi relativamente più sabbiosi, quelli che nell’ambiente marino-cosiero si posizionano più verso riva (spiaggia sottomarina) e che hanno subito un maggior rimaneggiamento dal moto ondoso. si spiega anche così la loro forma arrotondata e minuta. ipoteticamente, la provenienza di questi frammenti di cotto e laterizi può essere imputata a materiali persi da navi in rada in vicinanza di un attracco o porto commerciale che gravitava sull’antico litorale gradese. 4. considerazioni conclusive lo studio lito-biostratigrafico dei terreni attraversati dal sondaggio eseguito sul sagrato della chiesa di s. maria delle grazie di grado ha permesso di ricostruire i principali paleoambienti sedimentari del sottosuolo dell’isola fino alla profondità di -10,6 m dal livello del mare attuale. resti di manufatti ceramici inglobati in questi, poi, hanno consentito di abbinare all’evoluzione naturale del territorio la presenza antropica, determinata dalla frequentazione stabile o da una residenza vera e propria in terraferma (periodo romano a cavallo del i sec.) o da una frequentazione sporadica in mare, a ridosso della costa. ipotesi questa anche se non suffragata da evidenze consistenti, resa plausibile dalla funzione portuale di grado nell’antichità (gradus = scalo), dal ritrovamento al largo di grado di diverse navi tra cui una di età greco-italica (tortorici, 2000) e dalla presenza nel retroterra da venezia a trieste di numerosi manufatti greci, anche di pregevole fattura (soprintendenza del f.v.g., 1996-97). a completare questo quadro, si registra che diversi pescatori del posto segnalano nei fondali del golfo di trieste la presenza di manufatti litici (soprattutto ossidiane, scambiate per pezzi di carbone) che fanno almeno ipotizzare l’esistenza di una via commerciale transadriatica, utilizzata dall’età neo-eneolitica. 143ricostruzione paleogeografica ... sotto il profilo stratigrafico i depositi del sottosuolo gradese sono, dal basso verso l’alto (da -10,6 a -4,5 m dal l.m.m.), peliti molto sabbiose di ambiente marinolitorale, che passano gradualmente a sabbie pelitiche infralitorali (da -4,5 a -0,3 m) inglobanti al top resti di murature e quindi, gradualmente, a depositi più fini con accentuata bimodalità. la parte terminale del sondaggio (da -0,3 m a +1,4 m dal l.m.m.) è costituita da materiali vari (ghiaie, mattoni ecc.) che iniziano da uno scavo (testimoniato da un contatto netto, irregolare) riempito da riporti d’origine antropica, probabilmente connessi anche all’elevazione del piano di calpestio dell’isola a seguito dell’innalzamento del livello del mare da un lato e dalla subsidenza dall’altro (marocco, 2004). i dati sedimentologici, e soprattutto i log delle curve di frequenza dei sedimenti, disegnano nel sottosuolo, dopo una fase alternante basale, un progressivo innalzamento del fondale marino (che rimane in ogni modo sempre poco profondo e nell’ambito di una spiaggia sottomarina) che si attua con una sovrapposizione di depositi marini, quindi litorali e poi di spiaggia emersa. le analisi eseguite sulla malacofauna e microfauna a foraminiferi ed ostracodi si sono rivelate particolarmente sensibili per la definizione dell'evoluzione dei paleoambienti sedimentari. soprattutto in base alle microfaune a foraminiferi emerge che nell’ambito dell’ambiente marino si riconoscono, dal basso verso l’alto, momenti determinati da condizioni infralitorali, seguiti da altri più tipicamente circalitorali (parte intermedia del sondaggio), per poi ritornare a situazioni più prossime alla linea di riva (fase iniziale del processo). si evince, anche, che nelle associazioni microfaunistiche esiste una costante presenza di forme salmastre che palesano una relativa vicinanza alla costa o di un apporto d’acqua dolce fluviale. la situazione che si ricava dall’actuopaleontologia perfeziona la ricostruzione eseguita sulle sole basi sedimentologiche e fa risaltare un motivo stratigrafico determinato da un emiciclo trasgressivo-regressivo che si attua in ambiente marino poco profondo. ciò non ha riscontri nelle sequenze stratigrafiche appurate nel sottosuolo dei dintorni di grado, dove è presente una generale fase trasgressiva che interessa depositi continentali e, via, via, lagunari e marino-litorali, anche con sviluppi parziali o incompleti. in questa situazione di progressiva invasione del mare sulla terraferma, determinata dall’innalzamento del mare olocenico (e dalla subsidenza dei sedimenti sciolti), non contrapposta da una apprezzabile progradazione costiera, si inserisce la sequenza stratigrafica riscontrata a grado, che ha un valore locale. in realtà, una condizione abbastanza simile a quella qui individuata si trova sull’attuale delta del f. tagliamento (da -14,7 a -4,4 m di profondità; marocco, 1988) e viene determinata dal progressivo aggetto deltizio del fiume in un ambiente marino-litorale che si è attuato in circa 2.000 anni. come precedentemente detto, diversa è invece la situazione del sondaggio s12, poco ad est di grado, dove depositi lagunari e deltizi si sovrappongono da -9,9 a -6,5 m di profondità e di quello più a nord s11 (sempre in laguna di grado), in cui si rinvengono solamente sedimenti continentali (ca. 30 m) chiusi al tetto da depositi sabbiosi di genesi fluviale. 144 foto 1 resti di mattoni e ceramiche varie di epoca romana carotati nel sondaggio. il diametro del resto di mattone è 70 mm. brick and pottery remains of roman age drilled in the well. diameter of the brick remain is 70 mm. r. marocco et al. la sequenza stratigrafica individuata nel sottosuolo della chiesa di s.m. delle grazie rende manifesta la vicinanza di un delta fluviale e si allinea con la segnalazione di livelli di ghiaia sotto l’isola, posti a breve distanza dal sondaggio analizzato. con tutta probabilità l’emersione del “dosso di rena” è stata determinata dalla progradazione di un fiume che aveva messo foce a poca distanza dal castrum e che si è contrapposto all’innalzamento del mare olocenico (trasgressione versiliana). ciò modifica lievemente lo scenario raffigurato da marocco (1991) per il litorale gradese nella scansione temporale 4000 b.p. (fig. 6) e approfondisce l’insenatura tra i due lobi deltizi, sostenuti da differenti fiumi, a occidente e a oriente di grado. questa nuova situazione sposta leggermente più a nord la linea di costa dell’epoca, che si doveva ubicare all’interno dell’attuale laguna, ben prima della posizione del sondaggio s11 (isola di gorgo; fig. 1a), senza modificare di molto la posizione dell’antico fiume che sosteneva questo lobo. i risultati della presente ricerca aprono così una serie di scenari riguardanti la piana aquileiese e, specifica-tamente, l’annosa connessione tra i percorsi fluviali del natiso cum torre individuati a oriente di aquileia (fassetta et al., 2003) e quelli che gravitavano sul litorale gradese. sembra possibile, almeno su basi sedimentologiche – non confortate da dati cronologici – che il fiume (o i fiumi) che scorreva a est di aquileia in epoca romana abbia posto foce immediatamente a occidente del castrum gradese. ipotesi questa che verrà meglio indagata con ulteriori e mirate ricerche sul sottosuolo dei terreni intermedi a queste località. i pochi dati archeologici ricavati dal sondaggio eseguito sul sagrato della chiesa aprono un capitolo di storia non ancora scritto per questa parte terminale del grande emporio romano della colonia di aquileia. si è sempre ritenuto che lo scalo di grado (dal nome gradus) sia sorto in funzione della colonia romana al fine di garantire il controllo del mare prospiciente, sede dei più importanti traffici commerciali dell’alto adriatico. al di là da considerazioni talassocratiche che presumono sempre un’espansione delle popolazioni da mare a terra e non viceversa, i resti di costruzioni e i frammenti di ceramiche individuati nel sottosuolo palesano che il litorale era abitato almeno a partire dal i sec. a.c. ÷ i sec. d.c., dopo la fondazione della colonia romana. ma nel sondaggio sotto la chiesa di s. maria delle grazie si riscontrano minuti tritumi di ceramiche anche alla profondità di -4,6 / -6,2 m dal l.m.m., inglobati in depositi di un ambiente marino poco profondo. l’unico collegamento con possibili attività antropiche in questo contesto sembra poter essere ricercato nella rielaborazione del moto ondoso di materiali provenienti da navigli in rada, oppure dal trasporto litoraneo di materiale eroso dalla costa. non si esclude però una derivazione dalla terra via fiume come starebbero a dimostrare gli analoghi frammenti individuati sui letti dei fiumi che lambivano aquileia. nei primi due casi rimane implicita la presenza dell’uomo (sporadica o stanziale) in queste aree ben prima della fondazione della colonia romana. ciò appare plausibile se si tiene conto dei fiorenti insediamenti dei veneti nel retroterra (nella stessa aquileia pre-romana) e degli intensi scambi commerciali che via mare rifornivano queste popolazioni dell’alta italia. in questa cornice storica la costa nord adriatica doveva assumere un’importanza di posizione ben superiore a quella dell’immediato retroterra, collocazione questa degna di essere controllata attivamente, con insediamenti fissi. ma questo riguarderà il seguito della ricerca, che dovrà coinvolgere archeologi, storici e geologi in comunità d’intenti. ringraziamenti gli autori desiderano ringraziare il prof. n. pugliese per la determinazione degli ostracodi e per tutti i suggerimenti durante la stesura del testo e i neodottori e. lotti e a. toffoli, che con le loro rispettive tesine e tesi ci hanno affiancato in questa ricerca. grazie anche al dott. e. gordini dell’o.g.s. di trieste e al dott. t. quaia e c. landucci del disgam per le elaborazioni grafiche. il sondaggio analizzato in questo lavoro è stato eseguito dalla tecno futur services di modena, a seguito delle indagini preliminari per il progetto di restauro e di consolidamento della chiesa. la ricerca è stata condotta nell’ambito del progetto miur 60% “tutela, gestione e ripristino ambientale delle zone costiere”, coordinato da r. marocco. 145 fig. 6 – paleogeografia del litorale gradese 4.000 anni fa (modificata da fassetta et al., 2003): 1. presunti percorsi fluviali; 2. paleolinea di riva; 3. idrografia attuale; 4. attuale linea di riva; 5. paleolinea di riva proposta. palaeogeography of the grado littoral area at 4000 b.p. (modified after fassetta et al., 2003): 1. supposed palaeochannels; 2. palaeocoastline; 3. present hydrographic network; 4. present coastline; 5. paleaocoastline herein suggested. ricostruzione paleogeografica ... bibliografia albani a.d. & serandrei barbero r. (1990) i foraminiferi della laguna di venezia. università di padova, memorie di scienze geologiche, 42, 271-341. albani a.d., favero v. & serandrei barbero r. (1998) distribution of sediment and benthic foraminifera in the gulf of venice, italy. estuarine, coastal and shelf science, 46, 251-267. amorosi a., colalongo m.l., fasini g. & preti b. (1999) sedimentary response to late quaternary sealevel changes in the romania coastal plain (northern italy). sedimentology, 46, 99-121. amorosi a., colalongo m.l., fiorini f., fusco f., pasini g., vaiani s.c., & sarti g. (2004) palaeogeographic and palaeoclimatic evolution of the po plain from 150-ky core records. global and planetary change, 40 (1-2), 55-78. brambati a. 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(1912) geoidrologia dei pozzi profondi della valle padana (parte iii). ann. r. acc. agricoltura di torino, liv-lv, 387 pp. soprintendenza ai b.a.a.a.s. del friuli venezia giulia (1996-1997) prima dei romani. scoperte di preistoria e protostoria fra colline e mare. 32 pp. sgarella f. & montcharmont zei m. (1993) benthic foraminifera of the gulf of naples (italy): sistematics and autoecology. boll. soc. paleont. it., 32 (2), 145-264. tortorici e. (2000) un nuovo relitto di età repubblicana nel mare di grado. archeologia delle acque, 4, 91-98. 146 ms. ricevuto il 27 aprile 2005 testo definitivo ricevuto il 27 luglio 2005 ms. received: april 27, 2005 final text received: july 27, 2005 r. marocco et al. morphological and palaeoenvironmental evolution of the vendicio coastal plain in the holocene (latium, central italy) g. aiello1, d. barra1, t. de pippo1, c. donadio1, p. miele2 & e. russo ermolli1 1dipartimento di scienze della terra, università degli studi di napoli federico ii 2c/o dipartimento di scienze della terra, università degli studi di napoli federico ii 10, largo san marcellino – 80138 napoli (italy) corresponding author: prof. tommaso de pippo depippo@unina.it abstract: morphological and palaeoenvironmental evolution of the vendicio coastal plain in the holocene (latium, central italy). (it issn 0394-3356, 2007). morphological, stratigraphical and paleoecological studies carried out along the vendicio coastal plain (southern latium) allowed us to reconstruct the paleoenvironmental evolution of the plain in relation to holocene sea-level changes. on the basis of altitude, texture, microfossil and pollen content of sediments recovered in a 20 m borehole carried out on the backshore, three main transitional palaeoenvironments were recognised. particularly, the 14c dating of a peat layer at the boring base (-16 m a.s.l.), interbedded between sandy silt with organic matter and silty peat levels, gives an age of 7620 ±100 yr bp, equivalent to 8354-8524 cal yr bp. over these deposits, sands with pebbles, sometimes alternated with silt and sandy silt levels, lay. microfossil content, together with sediment features, confirms a transitional sequence from marsh (oligohaline) to lagoon (mesohaline-polyhaline), and finally to marine (littoral) environment, probably due to the last sea ingression related to the mid-holocene climatic optimum peak (~6000 years bp). pollen analysis reveals the existence of a deciduous forest association, rich in high-humidity demanding elements, by now not represented by a regional modern analogue. the present altitude of the dated peat level, correlated with the available eustatic curves, suggests that the vendicio sedimentary succession probably has been affected by a slight subsidence phase during mis 1. the occurrence of a slight subsidence may be also related to late quaternary vertical displacement of adjacent coastal sectors, and fits in with recent morphological evolutionary models of other minor coastal plains of latium. riassunto: evoluzione morfologica e paleoambientale della piana costiera di vendicio (lazio, italia centrale). (it issn 0394-3356, 2007). lo studio delle caratteristiche morfologiche, stratigrafiche e paleoecologiche, connesse a variazioni del livello marino, ha permesso di ricostruire l’evoluzione paleoambientale olocenica della piana costiera di vendicio, ubicata nel lazio meridionale. sulla base delle quote, dei caratteri tessiturali, dei microfossili e di analisi palinologiche condotte su campioni di sedimento, estratti da una carota della spiaggia emersa, sono stati riconosciuti tre differenti paleoambienti di transizione. in particolare un campione di torba alla base della carota (-16 m s.l.m.), posto tra alternanze di limi sabbiosi organici e livelli di torbe limose, ha fornito un’età radiometrica 14c di 7620 ±100 anni dal presente pari ad un’età calibrata di 8354-8524 anni bp. questa successione sedimentaria è troncata da depositi sabbiosi con ciottoli, talora alternati a livelli siltosi e siltoso-sabbiosi. le associazioni a microfossili calcarei di tali depositi, insieme ai caratteri sedimentologici, confermano una progressiva transizione da un ambiente oligoalino a mesoalino-polialino (da palustre a lagunare) ed infine il rapido passaggio a quello marino (litorale), in seguito all’ultima ingressione del mare correlabile al picco dell’optimum climatico medio-olocenico (~6000 anni bp). l’analisi pollinica indica la presenza di una ricca associazione di foresta decidua, con elementi tipici di suoli molto umidi, che non ha riscontro nell’attuale ambiente regionale. la correzione della quota di paleodeposizione del livello torboso datato, condotta mediante le curve eustatiche tratte dalla letteratura, suggerisce che la successione sedimentaria verosimilmente è stata interessata anche da una lieve fase di subsidenza della piana nel corso del mis 1. quest’ultima potrebbe essere connessa a movimenti verticali registrati nel tardo quaternario in settori costieri adiacenti alla piana, in accordo con i recenti modelli morfoevolutivi di altre piane costiere minori del lazio. key-words: coastal geomorphology, lagoons, sea-level changes, holocene, italy. parole chiave: geomorfologia costiera, laguna, variazioni del livello marino, olocene, italia. il quaternario italian journal of quaternary sciences 20(2), 2007 185-194 1 introduction the present study represents a further contribution to the understanding of the holocene sea level rise in southern latium minor coastal plains. a substantial stability of the rocky promontories and a slight subsidence in the plains is indicated for this coastal sector since mis 5.5 (lambeck et al., 2004a; ferranti et al., 2006). no other data are available for the holocene sealevel changes along this coastal zone, apart from geoarcheological evidences in the sites of sarinola and serapo which show during the roman age a sea level of about 1.35 m lower than the present-day (lambeck et al., 2004b). the recovery of a sediment core, on the backshore of the vendicio beach, allowed a paleoenvironmental reconstruction to be performed through paleoecological, sedimentological and palynological analysis and correlated with the evolution of adjacent coastal sectors during the early holocene, where differential vertical movements occurred especially in quaternary times (bordoni & valensise, 1998; antonioli et al., 2006; de pippo et al., 2007). 2 geological and geomorfological outline the vendicio coastal plain is located in southern latium and extends for about 2 km from the headland 186 g. aiello et al. of mount conca, to the w, to marina di castellone, to the e (fig. 1). the coastal sector is bounded, to the ne and nw, by nw-se faults. one of such faults, named gaeta-itri-monte calvo, sharply separates the northeastern area, where cretaceous carbonate dominates, from the southwestern area, where triassic-giurassic dolomite outcrops prevail (servizio geologico d’italia, 1968). moving further away from this line and up in the succession more limestones, giurassic in age, are present, as one can observe along the slopes of lisantro and dragone mounts (de riso, 1964). finally, the coastal exposures show the top of the succession, mainly represented by cretaceous limestones, followed by prevailingly continental pleistocene and holocene deposits (hearty et al., 1986a; 1986b; hearty, 1986; accordi & carbone, 1988). the carbonatic succession, heavily crossed by a network of structural discontinuity with apenninic (nw-se) and anti-apenninic (ne-sw) trends (ambrosetti et al, 1987; c e r i s o l a & m o n t o n e , 1992; carrara, 1995a; 1995b; carrara et al., 1995), have a pronounced influence on the local geomorphological setting. owing to the strict correlation between the tectonic structure and the morphological evolution of the area, the slope of the relief are fault scarp or fault-line scarps, locally also modelled by karstic and denudation processes. therefore, the landscape is characterised by a series of hills often with a cone or truncated cone shape. their slopes are generally of a structural type and separate valleys, which develop according to local tectonic lines, mainly with nwse and ne-sw trends, subordinately e-w ones. the alternation of pocket beaches along the coast is also related to the presence of faults, prevailingly those ne-sw oriented. cliffs were also controlled by tectonics in their development, as noted for the dead or fossil cliffs of mount orlando and those of mount moneta, in the hinterland of the plain of sant’agostino, to the sw. the headland of mount orlando, the highest coastal relief, is constituted by cretaceous limestones with a prevalent eastward dip. the northern slopes are modelled with gentle forms covered by clastic deposits, such as the red sands referable to the lithologic unity called duna rossa antica (ancient red dune: blanc et al., 1953; bergomi et al, 1969; bono, 1985; dai pra, 1995), attributed to middle-upper pleistocene, and colluvial detritus partially pedogenesized and vegetated (valente, 1999). the cliff of mount conca, bordering the western side of the vendicio beach, continues under the sea down to about -5 m, where a sandy bottom is present. this coastal segment is characterised by a sandy beach, locally with pebbles, located between the rocky headlands of mount conca and formia. behind the modern dune ridge, hardly dismantled, a minor alluvial plain is also present, delimited in the ne by the southwestern slope of costamezza hill, a palaeocliff oriented nw-se, as the local tectonic alignments. evidence of ancient sea-level standings are scarce along the cliffs of the rocky headlands bordering the beach. at their bases a sandy bottom is usually present, which gently degrades down to -15/-25 m. steep slopes, in a range between -20 and -50 m depth, are present along the submerged southwestern sector. the ne-sw trend (antonioli, 1991; 1995; valente, 1999; miele, 2003) of such morphological elements suggests a structural control, which also influences the direction of the transversal elements, such as the wide fractures which tend to isolate stacks as at montagna spaccata, to the sw. here, some caves, remodelled both by waves and karstic phenomena, continue under the sealevel. along the southwestern coast, evidence of paleosea-level positions are numerous (antonioli et al., 2006; de pippo et al., 2007). in particular, along the slopes of fig. 1 geological outline of the vendicio coastal plain, between gaeta and formia (southern latium, central italy): 1) altitude (m a.s.l.); 2) isobath (-m a.s.l.); 3) mesozoic carbonatic outcrops; 4) miocene flysch; 5) pliocene conglomerate; 6) lower pleistocene-holocene carbonatic talus with pyroclastic levels; 7) upper pleistocene reddish eolian deposits (duna rossa antica formation); 8) upper pleistocene-holocene alluvial deposits; 9) holocene eolian deposits; 10) present-day sandy beach; 11) pleistocene detritic-alluvial fan; 12) fault: a) certain; b) presumed or buried. schema geologico della piana costiera di vendicio, ubicata tra gaeta e formia (lazio meridionale, italia centrale): 1) quota (m s.l.m.); 2) isobata (-m s.l.m.); 3) affioramenti carbonatici mesozoici; 4) flysch miocenico; 5) conglomerato pliocenico; 6) detrito carbonatico con livelli piroclastici del pleistocene inferiore-olocene; 7) depositi eolici rubefatti (formazione della duna rossa antica) del pleistocene superiore; 8) depositi alluvionali del pleistocene superiore-olocene; 9) depositi eolici olocenici; 10) spiaggia sabbiosa attuale; 11) conoide detritico-alluvionale pleistocenico; 12) faglia: a) certa; b) presunta o sepolta. moneta and lisantro mounts, sea-notches, marine terraces, fringe boring by bivalve such as litophaga litophaga linneo and drapes of sediments are present. some marine forms are also preserved along the fossil sea cliffs bounding the vendicio coastal plain. in the western area, along the mount conca cliff and at the back of the waterfront, a sea-notch can be observed at about +0.5 m, bored by l. litophaga linneo. some relics of marine terraces are also present, partially covered by breccias probably referable to the würm regression (mis 2). such breccias are heterometric, seaward dipping, often rubefact in the matrix. in the lower stratigraphic terms mollusc shell debris occurs, consisting of minute bivalve (i.e. glycymeris sp.) and gastropod fragments. such deposits, originated in the intertidal zone, where clasts either from the sea and from the land were deposited without a significant transport, are rather diffuse along this coast, even if sometimes with a negligible thickness. a careful observation of the isobaths, concave seaward in the area in front of the beach and convex and close together in the area where the rocky coast is stretched out, confirms that, under the loose sedimentary mantle which at present covers the sea-bottom, the morphology of the submerged coast, characterised by marine terraces (segre, 1949; antonioli, 1991; 1995), is controlled by the same structural pattern of the emerged area. 3 materials and methods a 20 m long soil boring was carried out on the backshore of the vendicio plain (fig. 2). a peat level is present at the boring base (-16 m a.s.l.), interbedded between sandy silt with organic matter and silty peat levels (a: between -17 and -3 m a.s.l.). the ams 14c dating of the bulk (geochron laboratories usa, sample nr. gx-32021) gives a 7620±100 yr bp age equivalent to 8354-8524 cal yr bp (calib 5.01 – stuiver & reimer, 1993; reimer et al., 2004). above these deposits, sand with pebbles, sometimes alternated with silt and sandy silt levels, lay (b: between -3 and -1.5 m). finally, over these sediments an anthropogenous top soil formed by colluvial layers, carbonatic boulders with litophaga litophaga boreholes, pebbles, sand and landfill, lay. (c: between -1.5 and +3 m a.s.l.). geomorphological surveys have been performed along the emerged coastal belt, characterised by limestone cliffs bordering a plain with dune ridge and partially anthropised. the geomorphological features have been considered in order to obtain a complete outline of the morphostructural arrangement of the investigated area. environmental features related to ancient positions of the sea-level have been recognised and interpreted, and therefore ascribed to a certain chronological interval thanks to the 14c dating of a boring sample. the correspondence existing between some of the recovered elements, their dating and the sea-level position in the last 8400 years (mis 1), allowed a correlation with the eustatic curves relative to the tyrrhenian sea in the same range of time. remarkable discrepancies exist among the eustatic curves plotted for different geographic areas. therefore, the curve covering the last 22.000 years, after alessio et al. (1996), and 187morphological and palaeoenvironmental evolution ... fig. 2 1) stratigraphic log of the soil boring (s) carried out on the backshore of vendicio: a) darkish sandy silt with organic matter, blackish peat and silty peat levels (brackish with fresh water environment); b) greyish and yellowish fine sand with limestone pebbles, sometimes with greyish silt and sandy silt levels interbedded (littoral environment); c) anthropogeneous top soil formed by carbonatic boulders with lithodomus boreholes, pebbles, sand and landfill (continental environment); 2) paleosalinity diagram of soil boring base, desumed from microfossil association analysed in the sediments: a1) oligo-mesohaline environment; a2) presumed oligo-mesohaline environment; a3) meso-polyhaline environment; *) dated peat sample (7620±100 yr bp 14c age equivalent to 8354-8524 cal yr bp); v1 = sample for palaeoecological and pollen analyses. altitudes are related to present-day sea-level (±m a.s.l.). 1) stratigrafia dei terreni presenti nel sondaggio (s) ubicato nella spiaggia alta di vendicio: a) limi sabbiosi organici, torbe e livelli di torba limosa di colore nerastro (ambiente salmastro con acque dolci); b) sabbie fini grigiastre e giallastre con ciottoli calcarei, talvolta con intercalazioni di livelli limosi e limososabbiosi (ambiente litorale); c) suolo di genesi antropica formato da blocchi carbonatici con fori di litodomi, ciottoli, sabbie e terreno di riporto (ambiente continentale); 2) diagramma della paleosalinità dei depositi presenti alla base del sondaggio, desunto dall’analisi delle associazioni di microfossili nei sedimenti: a1) ambiente oligo-mesoalino; a2) presunto ambiente oligo-mesoalino; a3) ambiente meso-polialino; *) campione di torba datato (età 14c di 7620 ±100 anni bp, equivalente a 8354-8524 anni bp calibrati); v1 = campione per analisi paleoecologiche e polliniche. le quote sono riferite al livello marino attuale (±m s.l.m.). 188 that covering the last 10.000 years, after lambeck et al., (2004a), both plotted by those authors with data collected in the more stable coastal areas of the tyrrhenian sea, were chosen as a reference. paleoecological and palynological analysis were only carried out on the lower part of the core where the sediment grain size and nature was more suitable for fossil preservation. eleven core samples (300 g dried weight) were disaggregated, washed with water through 200 mesh sieves (75 µm) and analysed with the aim of studying calcareous microfossil assemblages. attention was focused especially on ostracod and foraminifer taxa. all the samples yielded at least a few calcareous fossil remains. assemblages are characterised by the presence of ostracods, benthic foraminifers, bivalves, gastropods (shells and opercula) and charophyte oogonia. pollen analysis was carried out on 8 core samples, from -16.55 to -15.15 m a.s.l. chemical (hcl and hf) and physical (10µ filtering 200µ, heavy liquid separation) procedures were used to concentrate the pollen grains in the residue. all samples resulted rich and with a good pollen preservation. pollen sums range from 379 to 684 pollen grains. concentration values oscillate around 70-100.000 grains/g and reach about 200.000 grains/g in the richest levels. 4 calcareous microfossil assemblages the benthic foraminifer assemblages include six species pertaining to five genera; the ostracod assemblages consist of seven species in seven genera. taxa are listed in table 1. some species have been figured in plate 1. semiquantitative abundance of fossil taxa in the samples is represented by the following abbreviations: vr (very rare), r (rare), u (uncommon), c (common), a (abundant). palaeoecological interpretations follow the modern literature on recent paralic/shallow-marine benthic foraminifers and ostracods (i.a. barbeitogonzalez, 1971; hiller, 1972; bonaduce & masoli, 1974; vesper, 1975; bonaduce et al., 1976; hartmann & hiller, 1977; meisch, 2000). the studied specimens are housed in the aiello barra micropaleontological collection (a.b.m.c.), dipartimento di scienze della terra, università degli studi di napoli federico ii, naples (italy). assemblage analysis allows the analysed section to be subdivided into three intervals (fig. 2): a1 – the lowermost sample, v1, yielded an ostracod assemblage dominated by candona neglecta and, subordinately, by potamocypris fallax. ilyocypris bradyi is rare as well as gastropods. these species indicate a tab. 1 semiquantitative distribution of the calcareous remains in the vendicio plain core (a = abundant, c = common, u = uncommon, r = rare, vr = very rare). distribuzione semiquantitativa dei microfossili calcarei presenti nel sondaggio della piana di vendicio (a = abbondante, c = comune, u = poco comune, r = raro, vr = molto raro). samples v1 v2 v3 v4 v5 v6 v7 v8 v9 v10 v11 depth (m a.s.l.) taxa foraminiferida ammonia tepida cushman, 1926 c u c r a u c bolivina sp. vr elphidium cuvilleri lévy, 1966 u vr vr elphidium paralium (tintant, 1954) u u c vr u fursenkoina acuta (d'orbigny, 1846) vr quinqueloculina milletti (wiesner, 1912) c c a u u ostracoda ilyocypris bradyi sars, 1890 vr r candona neglecta sars, 1887 a r cyprideis torosa (jones, 1850) a a a u c c leptocythere rara (g.w. müller, 1894) vr loxoconcha stellifera g.w. müller, 1894 u c c c u u potamocypris fallax fox, 1967 c pseudocandona sp. vr bivalvia r a c a a r r gastropoda u vr u u u c a u a u u characeae vr vr 1 6 .5 5 -1 6 .6 0 1 6 .3 0 -1 6 .3 5 1 6 .1 5 -1 6 .2 0 1 5 .9 0 -1 5 .9 5 1 5 .7 0 -1 5 .7 5 1 5 .5 0 -1 5 .5 5 1 5 .3 0 -1 5 .3 7 1 5 .1 5 -1 5 .2 0 1 4 .9 5 -1 5 .0 0 1 4 .8 5 -1 4 .9 0 1 4 .7 5 -1 4 .8 0 g. aiello et al. 189 plate 1 fig. 1 quinqueloculina milletti , 4 chamber side, v9, (x 67). fig. 2 elphidium paralium, side view, v9, (x 53). fig. 3 elphidium cuvilleri, side view, v9, (x 37). fig. 4 ammonia tepida, spiral side, v9, (x 48). fig. 5 cyprideis torosa, left valve, v7, (x 68). fig. 6 cyprideis torosa, right valve, v7, (x 77). fig. 7 loxoconcha stellifera, right valve female, v7, (x 66). fig. 8 loxoconcha stellifera, right valve male, v7, (x 76). fig. 9 potamocypris fallax, left valve, v1, (x 68). fig. 10 leptocythere rara, right valve, v9, (x 75). tav. 1 fig. 1 quinqueloculina milletti, veduta del lato a 4 camere, v9, (x 67). fig. 2 elphidium paralium, veduta laterale, v9, (x 53). fig. 3 elphidium cuvilleri, veduta laterale, v9, (x 37). fig. 4 ammonia tepida, veduta del lato spirale, v9, (x 48). fig. 5 cyprideis torosa, valva sinistra, v7, (x 68). fig. 6 cyprideis torosa, valva destra, v7, (x 77). fig. 7 loxoconcha stellifera, valva destra femminile, v7, (x 66). fig. 8 loxoconcha stellifera, valva destra maschile, v7, (x 76). fig. 9 potamocypris fallax, valva sinistra, v1, (x 68). fig. 10 leptocythere rara, valva destra, v9, (x 75). morphological and palaeoenvironmental evolution ... 190 depositional paleoenvironment characterised by continental, oligohaline to mesohaline, relatively cold (<20°c), stagnant waters. benthic foraminifers are not present; a2 – the overlying interval is represented by three samples (v2, v3, v4) devoid of both ostracod and foraminifer specimens. calcareous fossil remains are represented exclusively by rare gastropods fragments and opercula. the sediment consists largely of carbonaceous matter derived from plant remains. the accumulation of organic matter generates the formation of acidic bottom and pore waters, due to the high concentration of metabolically produced carbon dioxide (co2). a low carbonate saturation index may cause the dissolution of the delicate ostracod shells. consequently, these sediments possibly indicate the effect of a cold and arid climate phase in a swampy environment (i.a. gliozzi & mazzini, 1998; belis et al., 1999); a3 – in the seven samples belonging to the upper part of the core (v5 – v11) benthic foraminifers are present and the fossil assemblages are generally richer and less oligotypic than in lower deposits. these portions show a more or less marked influence of marine waters, and the assemblages indicate four different paleoenvironments: samples v5, v6, v7, v11. ostracod assemblages consist of two species: cyprideis torosa, which is very abundant, and, subordinately, loxoconcha stellifera. the foraminifer assemblages are characterised by ammonia beccarii, quinqueloculina milletti and the genus elphidium (these latter not present in sample v6). the assemblages evidence a deposition in polyhaline waters; sample v8. abundant carbonaceous matter, rare specimens of ammonia beccarii and elphidium cuvilleri and the absence of ostracod shells indicates that these sediments were deposited in conditions similar to those in interval 2, but in polyhaline waters; sample v9. three ostracod and six foraminifer species occur, including leptocythere rara, fursenkoina acuta and bolivina which are recorded exclusively in this assemblage. the highest diversity possibly corresponds with the maximum influence of sea waters; sample v10. this assemblage is the only one which shows the presence of ilyocypris bradyi and pseudocandona sp., nonmarine taxa, together with the “marine-brackish” species l. stellifera, q. milletti and e. cuvilleri, suggesting a deposition in mesohaline-polyhaline waters, possibly with rapid (seasonal) salinity variations. 5 palynology pollen analysis results are presented in a detailed pollen diagram (fig. 3) where all the recognised taxa show their percentage values plotted against depth. the arboreal taxa percentage (ap/total curve in fig. 3) was calculated on a pollen sum excluding indeterminate grains, water plants and spores. ap values oscillate around 90% all along the investigated succession giving the image of a rather dense forested landscape (i.a. heim, 1970) in which the main arboreal elements were alnus, corylus, deciduous quercus, carpinus and ulmus. the only ap reduction is observed at 15.50 m depth where a rise in poaceae turns the ap down to fig. 3 detailed pollen diagram. taxa percentages are plotted against depth. diagramma di dettaglio dei pollini. le percentuali dei taxa sono restituite con le relative profondità. g. aiello et al. 68%. the arboreal taxa percentage (curve ap/total in fig. 3) oscillates from 60 to 80% giving the image of a rather dense forested landscape (i.a. heim, 1970). the main arboreal elements are alnus, corylus, deciduous quercus, carpinus and ulmus. deciduous quercus and carpinus do not show important variations. they probably represent the main elements of a slope forest association, established on well drained soils. on the contrary alnus, corylus and ulmus, which are high soil-humidity demanding elements, show more significant percent variations maybe linked to waterbed oscillations. in fact, they should have occupied the vendicio plain in a forestal association by now not represented by a regional modern analogue. vegetation associations dominated by alnus, corylus, carpinus and ulmus now characterise high humidity environments linked to microclimatic conditions, well represented all over italy (pedrotti & gafta, 1996). these elements are also commonly present in alluvial environments of temperate regions in central europe (polunin & walters, 1987) where they form plain-wood strips, by now relicts in italy and have almost disappeared from southern italy, a part from the higrophylous woods of mount circeo (stanisci et al., 1998). small amounts of fagus and betula are the only representatives of the mountainous vegetation belt. mediterranean elements are present but rare all along the analysed succession apart from a slight increase in quercus ilex towards the top. poaceae are the main representatives of the herbaceous elements; their percentages are always below 10% apart from the sample at -15.50 m where they reach 30%. the low percentage of spores and the relative lower percentages of alnus at the same core depth could indicate the reduction of dump soils around the drilling site. cyperaceae are rare but show a slight increase at -15.90 and -16.15 m; the correspondence with the highest values of alnus could indicate the extension of wetlands in the vendicio plain. it is very interesting from a phytogeographical and bioclimatic point of view the constant presence of vitis sp.. the species vinifera, as its wild representative, are now associated with the above mentioned arboreal elements in thermophilous humid forests from central to southern italy (pignatti, 1982) even if the wild representative is in constant regression all over europe (arnold et al., 1998). the 14c age of 7620+/-100 yr bp (8354-8524 cal yr bp) obtained at -16 m a.s.l. places the analysed succession at the beginning of the atlantic chronozone (about 9000-5700 cal yr bp), the holocene thermal optimum (ravazzi, 2003), which is characterised by wetter (about +200 mm/a) and cooler (about -1.5°c tann) climatic conditions in respect to modern values (terral & mengual, 1999; davis et al., 2003; magny et al., 2003). these climatic conditions associated with the humid edaphic conditions typical of a coastal plain can explain the existence of a forestal association like the one recognised in the core. 6 discussion and conclusions in this work the morphological and palaeoenvironmental evolution of the vendicio coastal plain is depicted for the first time (fig. 4) as sedimentological and ecological signatures of ancient coastlines. the analysed sedimentary succession starts in the early 191 holocene (about 8400 yr bp) and covers the main phases of the mid-holocene eustatic sea-level rise. three main transitional palaeoenvironments are recognised in the basal part of the core, on the basis of height, texture, microfossil and palinological analyses. pollen analysis reveals for the first time the existence of humid soils around the drilling site with the occurrence of a plain-forest where elements such as vitis are also recorded. microfossil assemblages together with sediment characteristics, indicate a transitional sequence from oligo-mesohaline to mesopolyhaline (from marsh to lagoon), and finally to marine (littoral) environment, due to the last sea ingression related to the mid-holocene climatic optimum peak (~6000 years bp). such environmental succession was also described in two 6 m long boreholes, carried out along the coastal sector west of formia. according to sewink et al. (1984), lagoonal clays with interbedded fine sand levels indicate a transition from brackish, with fresh water, to marine-brackish, probably littoral, environment. these deposits, intercalated towards the top with several paleosoils, are locally covered by roccamonfina tuffs, after an erosive phase. over this volcanic material, reddish, yellowish and reddish brown eolian sands as well as anthropogeneous colluvial layers are present, confirming the evolution towards a continental environment. in order to delineate the morphodynamic evolution of the vendicio coastal plain in the holocene, two eustatic curves (alessio et al., 1996; lambeck et al., 2004a), were chosen as a reference. the present position of the dated peat level in the study soil boring (-16 m a.s.l.) could indicate both stable conditions or the occurrence of a slight subsidence in the plain, in agreement with literature data (ferranti et al., 2006). on the basis of the chosen references, the sea level position at 8400 years bp was about -15 m lower than the present. the dated peat position at -16 m is consistent with a marsh to shallow water lagoon environment, in stable tectonic conditions. however, a slight subsidence could also be deduced for the considered time interval. no data are specifically available in this area which could better detail the sea level rise during the early holocene, but at 2000 years bp considering geoarchaeological data alessio et al. (1996) indicate a sea level of about 0.6-1.5 m lower than the present, while lambeck et al. (2004b) calculate a sea level of about 1.35 m lower than the current for the sites of sarinola and serapo, close to the study area. as a matter of fact differential movements between adjacent coastal sectors have occurred up to recent times (de pippo et al., 2007). such movements would have occurred along the nw-se faults that represent the borders of the pocket beach system characterising the entire coastal physiography. moreover, such discontinuities act as unblocking elements for adjacent coastal sectors. this fact suggests that the coastline did not behave homogeneously during the late quaternary tectonic phases, as hypothesized for some sectors of the campanian coastline (cinque & romano, 1990; de pippo et al., 1998; esposito et al., 2003). such dislocations, which occurred in the studied coast, can be referred to a sector of the central apennine included between the two main coastal plains of fondi and formia-garigliano where a slight subsimorphological and palaeoenvironmental evolution ... 192 fig. 4 probable palaeoenvironmental evolutionary model of the vendicio coastal plain, desumed from soil borings (see fig. 2 and citations) and morphological features; a) upper pleistocene lower holocene: marsh environment characterised by a coastal pond with debouching stream, dune ridge and beach; b) 8400 years bp mid holocene: development of the lagoon with bebouching stream and the mouth cutting the dune; retreating beach due to sea level rise; c) mid holocene present-day: gradual disappearance of the dune and lagoon; beach retreat due to both sea level rise and recent strong anthropogeneous intervention along the plain; 1) carbonatic rock; 2) duna rossa antica (ancient red dune) formation; 3) carbonatic talus; 4) marsh deposits; 5) eolic deposits 6) marine deposits; 7) lagoon deposits; 8) landfill. the blockdiagram is not in scale; the vertical wired arrow shows the sea level rise, while the horizontal grey the shoreline retreat. modello della probabile evoluzione paleoambientale della piana costiera di vendicio, desunto da sondaggi (cfr. fig. 2 e citazioni) e caratteri morfologici; a) pleistocene superiore olocene inferiore: ambiente palustre con stagno costiero alimentato dal corso d’acqua, cordone dunare e spiaggia; b) 8400 anni bp olocene medio: sviluppo della laguna alimentata dal corso d’acqua, con foce che disseca la duna; spiaggia in arretramento a seguito dell’ingressione marina; c) olocene medio attuale: graduale scomparsa della duna e del retrostante ambiente lagunare; arretramento della spiaggia a seguito sia dell’ingressione marina sia dell’intensa antropizzazione recente della piana; 1) roccia carbonatica; 2) formazione della duna rossa antica; 3) detrito carbonatico; 4) depositi palustri; 5) depositi eolici; 6) depositi marini; 7) depositi lagunari; 8) colmata artificiale. il diagramma stereo non è in scala; la freccia verticale indica la variazione del livello marino, mentre quella orizzontale grigia l’arretramento della linea di riva. g. aiello et al. dence is recorded. in fact, according to recent papers, the whole eastern tyrrhenian margin can be considered from stable to slowly subsiding from mis 5.5 (ozer et al., 1987; ferranti et al., 2006), even if in southern latium local uplift movements are estimated (de pippo et al., 2007). references accordi g. & carbone f. 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(1975) ein beitrag zur ostracodenfauna schlleswig-holsteins. mitteilungen aus dem hamburgischen zoologischen museum und institut, 72, 97-108. 194 ms. ricevuto il 30 maggio 2007 testo definitivo ricevuto il 3 settembre 2007 ms. received: may 30, 2007 final text received: september 3 , 2007 g. aiello et al. imp.calderoni_russo geoarchaeological stratigraphy and radiocarbon datings of a deposit from a site of the pompeian area (campania, southern italy) gilberto calderoni 1 & filippo russo 2 1 dipartimento di scienze della terra, università “la sapienza”, p.le a. moro 5, 00185 roma. 2 dipartimento di studi geologici ed ambientali, università del sannio, via port’arsa 11, 82100 benevento. corresponding author, e-mail: filrusso@unisannio.it. abstract: g. calderoni & f. russo, geoarchaeological stratigraphy and radiocarbon datings of a deposit from a site of the pompeian area (campania, southern italy). (it issn 0394-3356, 2007). in 1996 the archaeological excavations at st. abbondio locality, a site ubicated on the top of a small, 15 m high a.s.l., hill made up by distinct tephra emplacements and located at the edge of the roman town of pompeii, provided new data of great geoarchaeological concern for detailing the local history of the settlement pattern and of the environmental land exploitation of the pompeian area far before the roman times. from a geomorphological literature we know that the local relief is a volcanic relict that some 5.5 ÷ 4.5 kyr b.p. limited eastward the local reach of the coastal plain, on which the roman town of pompeii flourished. briefly, the geoarchaeological analysis of the findings in a deposit discovered in the archaeological site, in fair agreement with the measured 14c ages, revealed that the site-area, first occupied by an early bronze age settlement, was used as a necropolis in the middle bronze age and then, following a long lasting abandonment, was exploited for intensive farming throughout hellenistic and roman times. the stratigraphic sequence exposed by the archaeologic excavations, included some distinct, rich in artefacts, anthropic levels confined between the tephra ejected by mt. vesuvius during the last two huge plinian eruptions of avellino (best 14c age: 1410 ± 40 yr b.c.) and pompeii (79 a.d.). the archaeological excavations at st. abbondio site yielded a reference stratigraphic sequence for the area, particularly valuable because it uncovered, both prehistorical and historical artefacts which are strictly associated with a changing of land use perhaps related with palaeoenvironmental changes induced by locally recurrent natural dramatic volcanic activity. riassunto: g. calderoni & f. russo, stratigrafia geoarcheologica e datazioni radiocarboniche di un deposito multistrato rinvenuto in un sito dell’area pompeiana (campania, italia meridionale). (it issn 0394-3356, 2007). nel 1996 nella località sant’abbondio a pompei, poco distante dall’area dei noti scavi archeologici dell’antica città di epoca romana, gli sbancamenti operati per la costruzione di un edificio consentirono la scoperta di una interessantissima situazione geoarcheologica grazie alla quale, per la prima volta nell’area pompeiana, venivano alla luce resti di insediamenti più antichi dell’età romana ed in particolare dell’età del bronzo. in un’area dove la stratigrafia geoarcheologica era limitata al periodo romano e tardo antico, finalmente si poteva così documentare una storia degli insediamenti, e quindi dell’uso del territorio, più antica di quanto fino ad allora era conosciuto. ma, dal punto di vista geologico ambientale, la cosa più straordinaria emersa dallo scavo archeologico è stata la constatazione dell’esistenza anche nell’area pompeiana di uno strato eruttivo riferibile all’eruzione pliniana del somma-vesuvio nota col nome di “eruzione di avellino”, occorsa circa 1400 anni a.c. uno strato eruttivo fino ad allora poco conosciuto nell’area e meno ancora la sua interazione locale con i resti archeologici pre-pompeiani. dallo stesso punto di vista, inoltre, se si considera che gli scavi archeologici pompeiani rappresentano il dramma di una antica città vesuviana distrutta e seppellita dalle vulcaniti dell’eruzione pliniana del 79 d.c., con questa scoperta non solo si documenta una analoga tragedia umana ed ambientale vissuta molto tempo prima dalle popolazioni italiche localmente residenti, ma si arricchiscono gli scenari catastrofistici che per l’area vesuviana, in generale, prospettano come difficoltosa l’interazione tra lo sviluppo dell’urbanizzazione ed i problemi di pericolosità legati al vulcanismo attivo dell’area. il sito archeologico di sant’abbondio è ubicato sulla sommità di una collinetta di origine vulcanica alta poco più di 15 m s.l.m. che limita verso nw la locale pianura alluvionale e costiera su cui prosperava la città romana di pompeii. in accordo con le datazioni radiocarboniche, i resti archeologici rinvenuti nelle sezioni stratigrafiche e nell’area dello scavo di sant’abbondio rivelano che il sito fu occupato inizialmente da un villaggio risalente al bronzo antico successivamente trasformato in necropoli durante il bronzo medio e poi, dopo un lungo periodo di abbandono, fu sfruttato, a partire dal periodo ellenistico dell’antica pompeii, per coltivazioni agricole, prima di essere definitivamente occupato, nel i sec. d.c., dai resti di una fattoria di campagna distrutta dall’eruzione del 79 d.c. nello scavo archeologico il livello eruttivo riferibile all’eruzione di avellino ricopre sicuramente, ma senza apparenti segni di distruzione, i resti archeologici del villaggio del bronzo antico; purtroppo, non sono chiari i rapporti tra questo livello ed i resti multistratificati della necropoli del bronzo medio. livelli vulcanoclastici alluvionali, depositi di origine antropica e suoli sepolti completano la successione stratigrafica verso l’alto, sulla quale sorgono i resti di una fattoria di epoca romana distrutta e seppellita sotto diversi metri dai lapilli e dalle ceneri vulcaniche dell’eruzione del 79 d.c. sui quali oggi si sviluppa una estesa area edificata. oltre all’importanza della successione sedimentaria geoarcheologica, il sito di sant’abbondio documenta anche un’interessante variazione temporale di uso del territorio con le connesse attività umane; un aspetto, questo, che, come ipotesi di lavoro, potrebbe benissimo essere imputato ai cambiamenti ambientali indotti localmente dall’impatto drammatico dell’attività vulcanica vesuviana. keywords: gran sasso massif, calderone glacier, glacial oscillations, holocene climate, little ice age. parole chiave: stratigrafia geoarcheologica, datazioni radiocarboniche, eruzioni vesuviane, età del bronzo, pompei. il quaternario italian journal of quaternary sciences 19(2), 2006 261-268 262 g. calderoni & f. russo 1. introduction since long ago the archaeological community is addressing considerable efforts to gaining deeper insights into the palaeoenvironmental changes experienced by the pompeian area through the last five millennia, helping to answer the still numerous open questions on the spread of intermittent settlements throughout the pompeian area prior to the foundation of the roman pompeii and subsequently to its burial in 79 a.d. it is stressed that the palaeoenvironmental assessment is crucial, as the area experienced huge natural events that seriously affected the behaviour, spread and choice of settlement sites of the local ancient populations. the geoarchaeological studies carried out in the pompeian area till now have focussed on the relationship between roman and post-roman urbanization with the peculiar physical characteristics of the local volcanic and alluvial environment (sarno river plain), also concerning natural catastrophic events like the negative impact of 79 a.d. plinian eruption of vesuvius on the local roman settlements and landscapes (sigurdsson et al., 1985; cinque & russo, 1986; albore livadie et al., 1990; comentale, 2005). whereas, nothing is known about the same relationships regarding older settlements with their land use; in fact, only a few and scattered evidences of prehistoric occupations have been reported from both the excavated areas of pompeii (brunsting, 1975; wynia, 1982; de caro, 1985) and the surrounding territory (brunsting, 1975 and references therein; albore livadie et al., 1990). the discovery of a bronze age necropolis at st. abbondio, a site adjacent to the roman town of pompeii (mastroroberto, 1997; 1998 a, b), revealed to be of great geoarchaeologic concern for this stretch of the campanian coast in that the systematic excavation yielded a stratigraphic sequence of occupation levels, rich in well defined artefacts, confined within volcano-sedimentary layers recording the occurrence of dramatic natural events (like the volcanic eruptions). in this paper we document for the first time a geoarchaeological stratigraphy of a pompeian area where the relationships existing between bronze age/roman settlements and plinian eruptive levels are clearly exposed having greatly modified the local landscape and the anthropic land use. 2. geomorphologic and stratigraphic setting of the pompeian area the pompeian area lies on the south-eastern edge of the somma-vesuvius volcanic complex, almost at the northern part of the coastal plain that stretches southward to the surrentine peninsula (fig. 1). despite the plain undergoing an almost continuous subsidence since pleistocene times (e.g., some 1.6 myr ago), the overall trend of coastline resulted in a significant progradation owing to the aggradation of the notable amount of tephra issued by the numerous nearby vents intermittently active during pleistocene and holocene times (cinque et al., 1987). fig. 2 points out that the monotonous, almost flat fig. 2 geomorphologic sketch map of the coastal plain and volcanic piedmont where the study site is ubicated. the former stationings of the coastline during the holocene are shown. schema geomorfologico del contesto di pianura costiera/piedimonte vulcanico in cui l’area di studio è inserita. si riportano alcuni stazionamenti olocenici della linea di costa nella piana. fig. 1location of the archaeological area of pompeii. localizzazione geografica dell’area archeologica di pompei. landscape of the coastal plain is only interrupted inland by the modest volcanic relief on which lies the roman town of pompeii and seaward, by systems of poorly developed, (cinque, 1991) subarcuate ridges made up by littoral sediments. these latter are the relics of former coastal features pointing to a complex geomorphologic evolution of the area particularly enhanced during the last 6 kyr. the oldest, more inland coastline is quite well marked by the topography of the plain and likely records the peak of the holocene marine ingression, here set at 5.6 kyr b.p. by 14c dating (cinque, 1991). a further, recentmost elongated coastal ridge occurs some 1 km seaward to the previous analogue feature. it accounts for a phase of sea level standing that, based on radiocarbon readings, lasted from 4.5 kyr b.p. through the 6th century b.c. (albore livadie et al., 1990). the results of geomorphologic and geologic studies on the filling sequence of the plain (barra et al., 1989; albore livadie et al., 1990) established that the coastline at the times of the huge 79 a.d. plinian eruption was almost parallel and shifted some 700 m inland relative to the present one. the sediment assemblage recording the coastline in roman times was found from 3 to 5 m below the present s.l., thus providing evidence of the huge subsidence experienced by the plain during the past two millennia. the archaeological site of st. abbondio is located (fig. 2) just 4 km southeastward the roman town of pompeii on a well defined topographic high, 15 m high, locally dominating the ca. 6 m a.s.l. alluvial coastal plain which stretches seaward from its foot. to the s the transition between the st. abbondio high and the underlying coastal plain occurs through a sharp erosion scarp, a feature previously reported from other nearby sites of the pompeian area and referred to as a inactive coastal cliff (cinque & russo, 1986). the stratigraphy of st. abbondio high mostly consists of tephritic-leucitic lavas emplaced by a local prehistoric eruptive centre of the sommavesuvius volcanic complex (c i n q u e & i r o l l o , 2004; d i girolamo, 1968). the lava flows are discontinuously and uncomformably overlain by a sequence of tephra levels, in part reworked, with interbedded buried soils frequently containing archaeological remnants. on the top of lava flow, rolandi et al. (1997) has recognized, as the oldest tephra layer in the volcanic sequence of the area of the ruins of pompeii, a thin pumiceous-sandy level referred to the sarno eruption (ca. 17 kyr bp) of mt. somma-vesuvius. among the tephra layers, the thickest and mostwidespread, ashy and pumiceous in character, is that issued by the 79 a.d. vesuvius eruption responsible for the burial of pompeii (sigurdsson et al., 1985). 263geoarcheological stratigraphy and radiocarbon ... 3. chronostratigraphy of the deposit at st. abbondio site the archaeological site of st. abbondio was first reported in 1943, following the discovery of an isolated sanctuary devoted to dionysus that was dated back to the turn of the 2nd and 3rd centuries (elia & pugliesecarratelli, 1979). however, only following recent geophysical soundings (colombo et al., 1997) and systematic excavations (mastroroberto, 1997; 1998 a, b; d’ambrosio et al., 2001) a protohistorical necropolis, pointing to the occupation of the pompeian area during the bronze age, was found. the geoarchaeologic sequence investigated at st. abbondio is of great concern in that for the first time the remnants of the most ancient occupation so far uncovered over the area were found strictly associated with the tephra ejected by the somma-vesuvius during the huge plinian eruption referred to as “avellino’s eruption” (rolandi et al., 1993), which in nearby showings were dated (vogel et al., 1990) at 1410 ± 40 yr b.c. (calendar age: 1730 ÷ 1605 yr b.c.). the stratigraphy exposed on the walls of the excavated archaeological trench (fig. 3) consists of volcano-sedimentary sequences with interbedded buried soils. these latter features contain artefacts that point to several, distinct occupational phases and therefore provide us with a reference geoarchaeologic record for the area. at the bottom of the trench blackish tephritic-leucitic lavas (layer 1 in fig. 3) are exposed, with the typical silty-loamy, yellow-red coloured weathered cap (layer 2) that upward shows pedogenethic signs. evidences of human activity are scattered on the surface of the layer 2, sometimes they are (hut potholes – h in fig. 3) clearly cutting the layer itself. inside the upper part of the layer 2 were discovered lots of fig. 3 stratigraphy exposed on the walls of the trench excavated at st. abbondio archaeological site. key: see text. sezione geoarcheologica schematica esposta nelle pareti dello scavo archeologico di sant’abbondio (vedere il testo per la spiegazione dei numeri e delle lettere). 264 potsherds typologically assigned to the facies of palma campania (albore livadie, 1981) of the early bronze age. there is no sufficient data about but we think that the discovered pot-holes and potsherds are coeval and pertinent to the same, early bronze aged, primitive hut villages. the recognized graves (g) are shown in fig. 4. sometimes coalescent and containing personal belongings, they were covered and wall-faced with pebbles, cobbles and blocks (p) ranging in size from a few tens of cm up to 1 m wide, mainly composed of limestones, sandstones and lithified tuffs, subspherical in shape as a result of alluvial transportation. the graves cut the whole thickness of layer 2 and also the tracks of hut pot-holes; from an archaeological point of view in the outcropping area of graves there are no evidences of early bronze ages remnants. based on archaeological analysis the occurrence of graves could imply that the site was used as a necropolis, possibly at the boundary between early and middle bronze age (protoappenninico b). because there are no datable organic remains inside the pot-hole infillings, the approximate age of layer 2 can be deduced from the radiometric datings made on soil organic matter sampled from the layer itself. results of radiocarbon dating, carried out at the radiocarbon laboratory of the earth science department at rome university (calderoni & petrone, 1992), support the archaeological inferences in that the age of layer 2 is bracketed between 4900 ± 75 (rome979; bottom, calibrated age: 3760 ÷ 3640 yr b.c.) and 4300 ± 65 yr b.p. (rome-981, top, calibrated age: 3000 ÷ 2765 yr b.c.). this data set range archaeologically span throughout the copper age (from gaudo culture to andria-laterza facies), but unfortunately no archaeological data testifying the presence of copper age remnants in the st. abbondio site is documented. thus we accept as antequaem boundary the radiometric dataset obtained, believing them reliable. a 15 cm thick layer 3 of massive, ashy-glassysandy tephra, barren of any archaeological remnant, overlies conformably and continuously the previous layer. its overall features match those of the products, emplaced by the plinian avellino’s eruption of sommavesuvius (rolandi et al., 1993; ranieri & yokotama, 1997). apart from the lithological data the chronological assignment of layer 3 is also consistent with the results of two radiocarbon measurements (rome-980 and –982) on charcoal fragments that provided the weighted mean age of 3655 ± 40 yr b.p. (calendar age: 2110 1930 yr b.c.). in the archaeological site the charcoal fragments are positioned at the base of the layer 3. we suppose that the charcoal fragments could come from a very little lens, perhaps a hearth relic, hosted in an invisible erosional task on the top of layer 2. surely, there are no visible relationships between the supposed lens and the other anthropic remnants, but we believe that this supposed new anthropogenic level should be like an independent unit interposed between the layer 2 and the layer 3. upward a 20 cm thick ashly-sandy deposits (layer 4) occurs. it is devoid of archaeological remnants and displays clear signs of pedogenesis, such as sub-angular, weakly developed blocky structure, very dark brown colour, no hcl effervescence and very rare coarse fragments, these latter consisting of pumices of few millimetres in size: such pedogenic features strongly suggest that the soil at issue could represent the relict of a bw horizon of a soil developed from volcanic material and very probably displaying andic soil properties. such a soil developed atop the layer 3. the overlying layer 5, about 60 cm thick, consists of a reworked, roughly parallel stratified volcaniclastics alluvial conglomerates confined within two undulated surfaces likely affected by erosion. this is suggested by the occurrence of furrows (f), subtrapezoidally shaped and ca. 1 m wide, which record two parallel, nw-se aligned artificial channels possibly backdating to the times of the archaic pompeii (6th 4th centuries b.c.), as testified by artefacts discovered within (mastroroberto, pers. comm.). the top of level 5 shows a hearth floor (f), assigned to the middle of the 1st century a.d., complete of its foundation (h) composed by a mixture of volcanoclastic debris and hellenistic and roman potsherds dated from the end of the 3rd century b.c. to the middle of the 1st century a.d. layer 5 is capped by a 30 cm thick ashy-sandy deposit (layer 6) in which is founded a wall structure (w) relative to the late development of pompeii (62-79 a.d.). this layer displays clear signs of pedogenesis and consists of two soil horizons: the upper horizon, approximately 5 cm thick, is characterized by a verycoarse crumbly structure, very dark grey colour and no hcl effervescence and could be reasonably interpreted as the remnant of an a horizon; the lower horizon, approximately 30 cm thick, displays a moderately developed coarse sub-angular blocky structure, a dark greyish colour and no hcl effervescence: thus, it probably represents the remnant of a bw horizon. the overall soil developed from a volcanic parent material and probably displays andic soil properties. the soil is interested by subparallel ploughing furrows and further evidence of agricultural practices, is cut by an artificial, subtrapezoidally shaped channel (c) containing potsherds from the first half of the 1st century a.d. akin in the nearby archaeological area of pompeii, the studied geoarchaeological sequence is sealed by fig. 4 general view of the excavations at st. abbondio site (as of 1996). some of the uncovered graves (foreground) as well as features of the exposed sequence (background) are shown. features labeling as for fig. 3. veduta generale dello scavo archeologico di sant’abbondio nel 1996). i numeri e le lettere sono le stesse di fig. 3. g. calderoni & f. russo 265 the tephra (7), here only 2.5 m thick, issued by the 79 a.d. plinian eruption of vesuvius (yokoyama & marturano, 1997), with the present soil (8) at the top. from down to top, the layer 7 consists of white pumices (a) and two levels of grey pumices (b and d) alternating with two massive, pisolitic, ashy-sandy levels laid down by pyroclastic surges (c and e). 3.1. the new 14 c readings from the site of st. abbondio besides geomorphological and lithological considerations, valuable data for establishing the chronostratigraphy of the geoarchaeological deposit at st. abbondio were the 14c dates measured on materials in reliable association with the identified occupation phases of the site. in particular the dated materials were the topmost (rome-981) and lowermost (rome-979) portions of the buried soil referred as layer 2 and the charcoal from the fill of a lens, possibly a fire place remnant, underneath layer 3 (sample locations are given in fig. 3). the former sample pair was first pretreated for isolating the humic matter fractions of proved validity in 14c dating of paleosols (calderoni & turi, 1998), whereas the collected charcoal was split into subsamples rome-980 (smaller bits) and rome-982 (larger fragments) and routinely processed. following conversion into the benzene to be used as a counting medium, the 14c decay rate was measured by βspectrometry: details on sample processing, counting protocol, equipment and calculation of the conventional 14c ages were previously reported (calderoni & petrone, 1992). the results, both as conventional (yr b.p.) and calendar ages (yr b.c.) are shown in table 1. the sample pair from the fireplace (rome-980 and –982) yielded statistically indistinguishable ages (3690 ± 60 and 3620 ± 60 yr b.p., respectively) resulting in the 3655 ± 40 yr b.p. weighted mean. as suggested by the results of previous radiocarbon dating (calderoni & petrone, 1989) of nearby buried soils of comparable origin and development, the ca. 600 yr age difference between the base (rome-979, 4900 ± 75 yr b.p.) and the top (rome-981, 4300 ± 65 yr b.p.) of the dated buried soil from layer 2 is reasonably accounted for by the dynamics of the soil forming processes. the data pinpoints a significantly long time span of stable environmental conditions suitable for soil development, this being a notable event for the study area. finally, it is observed that the used tract of the calibration curve is quite favourable, in that it displays a smooth fluctuation pattern. as a result, according to the distribution (at ± 1 σ confidence level) of the relative area under the calibration curve the calendar intervals for samples rome-979 and -981 and the pair rome–980/-982 narrow to 3770-3635, 3035-2870 and 2035-1925 yr b.c. with a 96, 87 and 86% of probability, respectively. 4. final remarks although so far only the southernmost part of the study site has been systematically excavated, the obtained data proved quite adequate for assessing in fair detail the geoarchaeologic framework. furthermore, interbedded with and strictly associated to the layers several levels rich in prehistorical/historical evidences were found, effective for the archaeological setting, of human occupations. according to c o l o m b o et al . (1997) and mastroroberto (1997; 1998 a and b) the pot holes with associated potsherds and the graves (g) containing personal belongings 1 m deep, entrenched into the weathered part (layer 2) of the basal lavas flow, are related to two distinct human occupations, referred to the old bronze age and the transition to the middle bronze age, respectively. the age of the layer 2 is bracketed within the 3760 2990 yr b.c. calibrated time-span by two 14c readings and charcoal from upward the sequence yielded the 2100 1930 yr b.c. calendar interval. therefore the results of isotope dating suggest that during the bronze age the site witnessed two separate occupations over some less then two millennia, the last one lasting up to ca. 200 yrs prior to the 1730 1600 yr b.c. avellino’s eruption. the transition from prehistorical to historical times is marked by a 60 cm thick sandy matrix-supported conglomeratic deposit (layer 5) devoid of archaeological findings, points to an abandonment of the site. such a phase, lasted some 1000 yrs, spanning subsequently from the avellino’s eruption possibly up to the times of the archaic pompeii (6th through 4th century b.c.). we note that none of the features of the layer is suggestive of natural events of such a dramatic character to account for the absence of any hint of human presence over the area. the geoarchaeological deposit shows the most ancient and reliable traces of human activity in protohistorical/historical times at ca. 3.5 m deep, these being represented by the infilled trenches of two parallel ditches likely referred to the archaic pompeii (6th-4th century). just upward the re-settlement is strongly suggested by an almost complete hearth structure associated with hellenestic/ roman potsherds referred to from the 3rd century b.c. to the 1st century a.d. subsequently several table 1 14c readings for st. abbondio archaeological site. datazioni 14c effettuate nel sito archeologico di sant’abbondio. laborator identifier (rome) material stratigraphic conventional calibrated sample number location age (yr b.p.) age(1) (yr b.c.) 979 humic matter layer 2 4900 ± 75 3760 3640 981 humic matter layer 2 4300 ± 65 3000 2765 980 charcoal layer 3 3690 ± 60 2190 1945 982 charcoal layer 3 3620 ± 60 2030 1830 980/982 weighted mean 3655 ± 40 2110 1930 (1) calibration data set after stuiver & reimer (1993). geoarcheological stratigraphy and radiocarbon ... 266 aspects of the anthropic activity during the last development phase of pompeii are clearly well noticeable, e.g., a wall structure, potsherds, evidence of farming and water drainage. after which the archaeological sequence appears to have been suddenly sealed by the tephra of the 79 a.d. eruption. switching to the palaeoenvironmental changes of the area during the time span we are dealing with and taking into account the geomorphological evolution of the sarno plain resulting from the studies of albore livadie et al. (1990), we can conclude that at the times of the old bronze age occupation the topographic high of the study site ended with a sharp cliff directly on the coastline or on an alluvial coastal plain that, although subjected to fast progradation, was by far narrower than nowadays. subsequently, from 4.5 kyr b.p. the coastline migrated 1 km seaward where it stationed up to the 6th century b.c. given the above features it is conceivable that the area could have been attractive for the settlers because of its dominating location, availability of fertile soils as well as proximity to the exploitable resources of the sea and the coastal plain. so that the high of st. abbondio was abandoned after avellino’s eruption. with the soil formation on the top of layer 5, the anthropization of the st. abbondio area comes back and manufactured-structures serving the reclaiming and farming are made up, probably related to the expansion of the archaic pompei. since then and up to the first half of the 1st century only subordinate agricultural landscape changes and a discrete urbanization of the area had occurred; with the 79 a.d. plinian eruption the overall pompeian area was destroyed, completely buried, and for a long time forgotten till nowadays, thus also our site of st. abbondio was definitively abandoned. as a final remark we can conclude that the paper evidences the relationships striking the development of man and its activity in an area characterized by a strong volcanic hazard (somma-vesuvius active volcanic complex) and consequentially with high geomorphological dynamics (comentale, 2005): in fact, we document a changing of anthropic land use with several functions of the site during the epochs examined. furthermore, we also document a changing of topography with several elevations of the ground after every main sedimentary and catastrophic event. this prefigures a real risk situation still dominant unfortunately. this work has been made possible realized with the contribution of research funds (f.a.r., 2005) of the sannio university accounted to prof. f. russo. references albore livadie c., barra d., bonaduce g., brancaccio l., cinque a., ortolani f., pagliuca s. & russo f. 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(1982) the excavations in and around the house of m. lucretius fronto. in: “la regione sotterrata dal vesuvio. studi e prospettive”, napoli, 329 340. yokoyama t. & marturano a. (1997) volcanic products of the vesuvius eruption in ad. 79 at pompeii, italy. opuscula pompeiana, 7, 1 32. 267 ms. ricevuto il 20 febbraio 2006 testo definitivo ricevuto il 31 ottobre 2006 ms. received: february 20, 2006 final text received: october 31, 2006 geoarcheological stratigraphy and radiocarbon ... imp.dewaeledigreg.pala karst geomorphosites of monte albo (north-east sardinia) jo de waele, felice di gregorio & aldo pala department of geology, via trentino 51, 09127 cagliari e-mail: geoam@unica.it abstract: j. de waele et al., karst geomorphosites of monte albo (north-east sardinia). (it issn 0394-3356, 2005). in this paper the authors present the results of a study performed on the geomorphosites of the monte albo chain (north-east sardinia), an important karst area elongated in a ne-sw direction for a length of 30 km and a width of 5, starting from 50 m a.s.l. and reaching altitudes of more than 1100 m. this relief consists of middle jurassic-lower cretaceous sometimes intensely karstified dolostones and limestones covering with an unconformity a metamorphic palaeozoic basement. although the geomorphosites of monte albo are not so impressive as in other sardinian karst areas it seems noteworthy presenting them in the framework of this spectacular landscape unit that, in its whole, represents an area of great geomorphological interest. among the described geomorphosites many places with didactic surficial karst phenomena (karren fields of monte turuddò, suspended valley of janna nurai, solution flutes and kamenitza of punta catirina, macro-dolines of campu ‘e susu, sas puntas and altudè, ruin-like landforms of nuraghe litu ertiches, canyon of riu siccu), the structural geosite of punta azza ruja, the overthrusts and the conglomerates of cuile su ramasinu, the vertical cliffs of n-monte albo, the geological landscape of punta cupetti and the landslide of punta ervare 'e chervos and two places of hydrogeological interest can be mentioned (sinkhole of bonaettè and karst spring of fruncu ‘e oche). furthermore many subterranean places are enclosed, two vertical karst shafts (tumba ’e nudorra and tumba 'e nurai), several horizontal caves (sa conca ‘e crapa, omines agrestes, locoli, su santuariu, cane gortoé) and a natural tunnel (listincu). all these geomorphosites should be connected in a local network inserted in the monte albo landscape unit, already part of the geomining, historical and environmental park of sardinia (area 6), through the realisation of equipped pathways and the elaboration of explicative maps and panels and a website in which geology, geomorphology, karst, fauna, flora, archaeology and industrial archaeology are described. the explanation of the chain’s genesis, its evolution, its geodiversity and the single elements it contains can help the visitors in understanding the importance of geology and geomorphology on landscape evolution, flora and human activities, that combine in an educational model of great suggestion and efficiency. this proposal of valorisation of these landscape units and their geomorphosites could well be connected to other areas of the region, and the authors hope that the local and regional stakeholders will commit themselves in the valorisation of their territory, giving an important service to the many tourists that come and visit the monte albo. riassunto: j. de waele et al., geomorfositi carsici del monte albo (sardegna nord-orientale). (it issn 0394-3356, 2005). in questo lavoro gli autori presentano i risultati di una ricerca effettuata sui geomorfositi della catena del monte albo (sardegna nordorientale), un’importante area carsica allungata in direzione ne-sw per una lunghezza di 30 km ed una larghezza di 5, con quote che variano dai 50 m s.l.m. della piana fino ad oltre 1100 sulle cime più alte. la catena è costituita da dolomie e calcari di età giurassico medio-cretaceo inferiore, più o meno carsificati, che poggiano in discordanza sul basamento paleozoico metamorfico. anche se i singoli geomorfositi del monte albo non raggiungono l’importanza di quelli riscontrati in altre aree carsiche sarde, tuttavia essi caratterizzano questa spettacolare unità di paesaggio e ne fanno un’area di grande interesse geomorfologico. tra i geomorfositi scelti riportiamo molte morfologie carsiche di elevato interesse didattico e turistico-culturale (campi careggiati di monte turuddò, la valle sospesa di janna nurai, le scannellature e le vaschette di corrosione di punta catirina, le macrodoline di campu ‘e susu, di sas puntas e di altudè, le città di roccia di nuraghe litu ertiches, la gola di riu siccu), i geositi strutturali di punta azza ruja, di cuile su ramasinu e del versante nord della catena, il paesaggio geologico di punta cupetti, la frana di ribaltamento di punta ervare ‘e chervos e due luoghi di interesse idrogeologico (inghiottitoio di bonaettè e sorgente carsica di fruncu ‘e oche). inoltre, molte sono le grotte incluse nell’elenco, tra cui due voragini (tumba ‘e nurai e tumba ‘e nudorra), molte grotte suborizzontali (sa conca ‘e crapa, omines agrestes, locoli, su santuariu, cane gortoé) ed un traforo naturale (listincu). tutti questi geomorfositi potrebbero essere collegati in una rete locale all’interno dell’unità di paesaggio del monte albo e facente parte del parco geominerario, storico ed ambientale della sardegna (area 6), mediante la realizzazione di sentieri attrezzati, l’elaborazione di carte tematiche e pannelli informativi e la creazione di un sito web con l’illustrazione degli aspetti più significativi del paesaggio naturale ed umano. l’illustrazione del paesaggio e della sua evoluzione, della sua geodiversità e dei caratteri dei singoli geomorfositi che esso contiene può aiutare il visitatore a comprendere l’importanza della geologia e della geomorfologia per l’evoluzione del paesaggio e delle molteplici attività antropiche che vi si svolgono, creando un modello educazionale di grande suggestione ed efficienza. questa proposta di valorizzazione dell’unità di paesaggio e dei geomorfositi in essa contenuti potrebbe essere estesa anche ad altre aree della regione. gli autori auspicano che gli amministratori locali e regionali elaborino proposte di valorizzazione di questo territorio caratterizzato da molteplici valenze, dando un importante servizio non solo ai molti turisti che visitano il monte albo ma anche alla popolazione locale. keywords: jurassic limestones, karst, geomorphosites, monte albo, sardinia. parole chiave: calcari giurassici, carsismo, geomorfositi, monte albo, sardegna. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 145-153 146 j. de waele et al. 1. introduction the study of geomorfosites in karst areas has already brought our research team in many parts of the island; the gulf of orosei (barca et al., 1995), the iglesiente-sulcis area (de waele et al., 1998), the tacchi area (ardau & de waele, 1999; de waele et al., 2004). furthermore the twenty most important karstic geosites of the island have already been described (de waele et al., 1999) and at the moment one of us (de waele) is working on the inventory of natural hypogean geosites in the framework of a national research program performed together with the national geological survey (piccini et al., 2004). in the framework of the national project cofin 2001-2003 “geomorphosites in the italian landscape” our research team has continued these researches, and in this paper the results of a study on monte albo are presented. 2. geology monte albo is a karst area located in north-east sardinia, elongated from ne to sw for a length of 30 km and a width of 5 and reaching altitudes of more than 1100 m a.s.l.. the outcropping rocks can roughly be subdivided in a palaeozoic mainly metamorphic basement and mesozoic sedimentary sequences (fig.1). the characteristics of the palaeozoic rocks are related to the tectonic and metamorphic events of the hercynian orogeny (carboniferous-permian). in the south-eastern part of monte albo the basement is characterised by hercynian granites of permian age, while to the north the outcropping rocks are more or less metamorphic. petrographical and mineralogical studies have allowed to distinguish two important crystallisation episodes (franceschelli et al., 1982; elter & sarria, 1989) and four complexes of different metamorphic degree. the outcropping metamorphic rocks are, roughly from south to north, constituted of metasandstones, phyllites, micaschists, paragneiss, granodioritic orthogneiss and bird’s eye gneiss. after a long-during continental period, estimated from permian to lower jurassic, the sea started occupying the hilly hercynian peneplain during bajocian-bathonian. the jurassic-lower cretaceous ocean never reached great depths in the monte albo area, and the different carbonate facies evidence several shallow depositional environments, going from lagoons to coral reefs. this sedimentary sequence starts with dolostones containing limestone lenses, oolithic limestones and massive fossil-rich outer-shelf, reef, interreef and backreef limestones. the jurassic transgression starts with clastic sediments of the genna selole formation, represented by quartz conglomerates and sandstones with plant fossils typical of a fluvial or delta environment influenced by tidal movements (amadesi et al., 1961; fazzini et al., 1974; dieni et al., 1983). traces of this transgressional facies can be found at punta casteddu (south monte albo) (dieni & massari, 1971). upwards this facies becomes marly, typical of a littoral depositional environment, and the alternation of marl and dolostone beds preludes the dorgali formation dolostones (amadesi et al., 1961; calvino et al., 1972; dieni & massari, 1985; 1987). these dolostones are sandy in the basal levels becoming pure brownish dolostones in the upper beds and locally contain brachiopods, echinoids, ammonites, belemnites and foraminifers of bathonian-kimmeridgian. at monte albo this formation reaches a thickness of at least 300 meters in the western part (lula), but reduces to only a couple of meters in the eastern extremity (monte gutturgios). upon these dolostones two heterotopic limestone formations are reported: the s’adde limestones and the monte bardia formation (dieni & massari, 1985). the first formation is characterised by brownish microcrystalline limestones sometimes containing chert nodules, not well stratified at the bottom but extremely well bedded in the upper part. the fossil fauna (ammonites, belemnites, brachiopods, echinoids and foraminifers) gives an age of callovian-kimmeridgian. the monte bardia formation instead is composed of typical reef and bioclastic limestones, with frequent fossil corals (sometimes in life position) and their debris. the age of these limestones, based on corals, gastropods, algae and foraminifers is kimmeridgianberriasian (upper jurassic-lower cretaceous). the uppermost part of this formation is characterised by marly limestones sometimes with mud cracks and fauna of brackish water environments, introducing the deposition of lower cretaceous purbeckian sediments after a short interruption of sedimentation (massari, 1968). these last sediments, composed of marls and marly limestones locally rich in pyrite and organic material, have been deposited in a relatively deep and confined sea and can be found only in two tectonically disturbed areas southwest of siniscola (dieni et al., 1987). their age has been determined on the basis of foraminifers to valanghinian (dieni & massari, 1966). upper cretaceous is not present in the monte albo region, but the discovery of maastrichtian pebbles in the post-middle eocene conglomerate of cuccuru ‘e flores, outcropping in the central-eastern part of monte albo, indicates that these sediments were eroded in late mesozoic-early cretaceous times (busulini et al., 1984). the syn-tectonic continental cuccuru ‘e flores conglomerate was deposited after middle eocene during a tectonic instable and continental period related to the pyrenean and apennine collision (dieni & massari, 1965). the geological sequence of monte albo is completed with pleistocene gravitational deposits, mainly represented west of siniscola (flanks of punta cupetti) and quaternary deposits (alluvium, debris, etc.). the tectonic situation is dominated by two main transcurrent fault systems, ne-sw and e-w, associated with local transpressive and pull apart sectors caused by the continental collision between the apulian plate and the south-european margin during oligocene-lower miocene. the most important fault system in the monte albo area is directed ne-sw (e.g. nuoro fault), running parallel to the national road that connects nuoro with siniscola (carmignani et al., 1994; pasci, 1997). the movement of the transcurrent nuoro fault is left-handed and is believed to be several kilometres for a vertical displacement of approximately 1000 meters and has lead, in the monte albo area, to impor147karst geomorphosites ... fig. 1 – geological sketch map of monte albo with the location of the geomorphosites. carta geologica schematica del monte albo con l’ubicazione dei geomorfositi. tant overthrusting. along these overthrust surfaces many outcrops of the syn-tectonic cuccuru ‘e flores conglomerate can been found. from a morpho-structural point of view these tectonic movements have determined the typical landform of cuesta or hogback to the entire chain, with the more or less gently dipping back towards se (fig.2). 3. karst geomorphology the mesozoic dolostones and limestones of monte albo have been interested by karst processes since their early emersion (upper cretaceous), even though the major karst landforms can be referred to the plio-quaternary. dolostones (dorgali formation, dogger) are characterised by diffuse fractures and joints and a welldefined bedding causing ruin-like landforms (pinnacles) and scarcely developed micro-forms (essentially solution pans or kamenitze). intense fracturing and jointing leads the meteoric water immediately underground with scarce superficial runoff. caves in dolostones usually consist of vertical shafts in which the tectonic imprint is clearly distinguishable. limestones instead (s’adde limestone and monte bardia formation, dogger-malm) are generally microcrystalline and pure carbonates that are ideal for the development of micromorphologies 148 such as solution flutes, rillenkarren, kamenitze etc. (fig. 3). in these rocks interesting solution caves are also formed (e.g. conca ‘e crapa) characterised by phreatic rounded morphologies and well developed calcite concretions. in areas affected by important tectonics (e.g. the southwestern flank of monte albo) no important caves are known and landforms are very much influenced by the tectonic surfaces and subsequent differential erosion. the north-western flank of the mountain is much more exposed to rain than the south-eastern one, also because here are located the highest altitudes (punta catirina and monte turuddò 1127 m a.s.l.). this difference is also clearly visible in the surface landforms. karren fields are well developed especially on the southern slopes of punta sae mussinu, punta ferulargiu and punta su mutucrone. in many areas of high altitude (e.g. the flanks of punta catirina and monte turuddò) the exposed karren fields are much more rounded, being an ancient covered karst. in fact, deforesting of these areas probably goes back to the early 20th century and the covering soil has been washed away since then (fig. 4). a distinct feature on monte albo is the scarcely developed drainage pattern, meaning that seasonal runoff takes place along small river incisions generally directed towards the northwest and the southeast. between punta gutturgius and punta cupetti the valley s’adde cuts though the monte albo carbonates from nw to se and ends with the canyon of riu siccu located on the vertical walls of the southern flanks. this valley has probably been inherited from a period in which the drainage on the north-western palaeozoic basement was directed towards the se and represents thus the initial stage of the formation of a suspended valley. a beautiful example of this latter type is janna nurai, located between monte turuddò and punta catirina at an altitude of approximately 600 meters. this valley flows towards the east ending up in the macrodoline of altudè. this large and complex depression still reflects an ancient drainage pattern with a southwest-northeast direction, finding its natural outlet in the steep badde viola canyon, probably of a much more recent origin. but the most interesting karst landforms of monte albo are the two macrodolines of campu ‘e susu and sas puntas, located on the northeast flank of punta catirina, at an j. de waele et al. fig. 2 – schematic sections showing the structural and geological settings of: a) the two macrodolines campu ‘e susu and sas puntas; b) the two mountains of punta azza ruja and punta urros. for location see fig.1. sezioni schematiche che mostrano le condizioni geologico-strutturali di: a) le due macrodoline di campu ‘e susu e sas puntas; b) i due rilievi dolomitici di punta azza ruja e punta urros. per la localizzazione vedasi fig. 1. altitude of 950 and 900 m a.s.l. respectively (fig. 5). these large depressions are characterised by relatively steep slopes and an almost flat floor, with considerable dimensions (average width of 500 meters and length of almost 1 km). they are probably formed on a palaeovalley, successively transformed in large depressed areas that take the form o macrodolines: their genesis is thus only partially controlled by dissolution of limestone. a small outcrop of “éboulis ordonnées” on the northern slope of sa puntas would represent a pleistocene debris deposit produced by the breakdown of the valley walls. underground karst phenomena are not very well developed on monte albo, especially comparing this karst area with other neighbouring carbonate outcrops such as supramonte or the gulf of orosei. the majority of caves are characterised by vertical development, mostly fracture-controlled shafts with no horizontal branches. the best example of such type of cave is tumba ‘e nurai, a 100 meters deep karst pit with an elliptical plant of 6x12 meters. much more impressive is the spectacular tumba ‘e nudorra cave, a collapsed sinkhole of 45x30 meters width and a depth of 45 meters. this sinkhole resembles somewhat the famous 149 sil cave passage that crosses the punta listincu limestone ridge from side to side. the two active caves are cane gortoé and locoli. the first is located in the village of siniscola and is characterised by approximately 1 km of narrow horizontal cave passages occupied by two different subterranean rivers that join before emerging from the entrance. the second is located at the foot of the monte albo southern flank and gives rise during heavy rainy periods to the locoli river. this cave is characterised by impressive submerged passages for a total length of more than 1050 meters and a water depth of 80 (perna & murgia, 2002). 4. geomorphosites in the framework of the national project cofin “geomorphosites in the italian landscape” we have chosen the most interesting karst geomorphosites of monte albo on the basis of an exhaustive bibliographical research, on the analysis of aerial photographs and on detailed field work, inserting them in a geomorphosite database (tab. 1). karst morphology has previously been described by several authors (altara, 1964; mucedda, 1991; pala, 1998). the largest karst landforms on monte albo are the macrodolines: three of these have been inserted in our geomorphosite database: campu ‘e susu, sas puntas and altudè. all three are located in the southern part of the mountain, the first two northeast of punta catirina at an altitude of 950 and 900 m a.s.l. respectively, and altudè two km east of these about 300 meters lower (pala, 1998). all three have the shape of macrodolines, but are most likely genetically related to a post-tectonic tertiary (miopliocene) palaeo-drainage system that had a general w-e direction and drained a morphological height located to the west, now mostly eroded. especially the plain of altudè still reflects the complex pattern of several converging rivers. smaller dolines are scarcely represented on monte albo, except for the spectacular tumba ’e nudorra collapse doline located right on top of the homonymous mountain. tumba karst geomorphosites ... fig. 4 – geomorphological sketch map of the area of the two macrodolines campu ‘e susu and sas puntas. carta geomorfologica schematica dell’area delle due macrodoline campu ‘e susu e sas puntas. fig. 3 – some examples of karst microforms (monte turuddò and punta catirina). alcuni esempi di microforme carsiche (monte turuddò e punta catirina). “cenotes” of mexico, also for the presence of a luxuriant vegetation on its bottom. the horizontal caves of monte albo can be subdivided in relict and active caves (mucedda, 1991). among the first su santuariu, conca ‘e crapa, omines agrestes and galleria listincu can be mentioned. the first three are relic caves with quite well developed chambers and cave passages characterised by important flowstones, while the fourth is a 20 meter long fos150 j. de waele et al. table 1 – the main characteristics of the geomorphosites of monte albo. le principali caratteristiche dei geomorfositi del monte albo. fig. 5 – the macrodoline campu ‘e susu seen from punta catirina towards the ne. the whole hogback of monte albo is clearly distinguishable. la macrodolina fotografata da punta catirina verso ne. l’intero hogback del monte albo è chiaramente visibile. n° name commune altitude morphotype access importance m a.s.l. 1 campu ‘e susu lula 980 macrodoline b l 2 sas puntas lula 895 macrodoline b l 3 tumba ‘e nudorra lula 910 collapse sinkhole c* r 4 conca ‘e crapa lula 1.055 cave b* l 5 su santuariu lula 240 cave b* l 6 omines agrestes lula 790 cave b* l 7 cane gortoe’ siniscola 45 cave a* l 8 tumba ‘e nurai lula 670 karst pit b* r 9 locoli lula 70 cave a* r 10 listincu lula 635 cave-tunnel c* l 11 bonaette’ lodè 550 swallow hole a l 12 altude’ lula 575 macrodoline a l 13 janna nurai lula 575 suspended valley b l 14 m.te turuddo’ lula 1.080 karren field b l 15 p.ta urros lula 475 geological structure b l 16 p.ta gurturgius lula 830 palaeo-landslide a l 17 p.ta catirina lula 1.090 karst landforms b l 18 s’adde-riu siccu siniscola 500 canyon c l 19 p.ta cupetti siniscola 1029 karst landscape b l 20 litu ertiches lula-irgoli 200 ruin like landscape a l 21 fruncu ‘e oche siniscola 48 karst spring a r 22 albo n flank lula-lodè 500-700 cliffs a l 23 cuile su ramasinu lula 400 tectonic features a l access: a=easy (close to roads), b=difficult (close to equipped pathways), c=very difficult (far from existing pathways and roads), *speleological; importance: l=local, r=regional ‘e nudorra is a unique example of collapse sinkhole and can be classified as one of the most beautiful ones of sardinia (loru & sechi, 1984). of different nature is the famous tumba ‘e nurai pit, located close to the janna nurai pass, constituted of a 100 meter deep karst pit (mucedda, 1983). this is the deepest pit of monte albo, known since a very long time also to local people who narrate fantastic stories about this hole, and it was explored for the first time by speleologist of trieste in 1955 (guidi, 2002). the nearby suspended valley of janna nurai is the most beautiful example of monte albo and one of the most interesting of sardinia. it is clearly visible from the village of lula and constitutes one of the few natural gateways to the mountain from the west. this ancient valley reflects a palaeo-drainage system, connected to the one of the three macrodolines, that flowed towards the east where it continued in the valley of altudè. the only valley that can occasionally become active on monte albo is the s’adde-riu siccu valley, that starts on the metamorphic rocks south of punta cupetti, directs towards the southeast and becomes a beautiful canyon before leaving the carbonate chain with a succession of vertical falls (loru & dore, 1994). from the southeast this valley is clearly visible and is also characterised by beautiful ruin-like landforms (pinnacles). these typical ruin-like landforms are even more developed and easily accessible close to the nuraghe litu ertiches where they form a labyrinth of dolomite rocks and pinnacles. karst micro-forms are not very well developed on monte albo and they are usually confined to monte bardia or s’adde pure limestone facies where slopes are not too steep and vegetation (thus soil) is not too thick. two places are of special interest and have been chosen as geomorphosites: the monte turuddò karren fields and the punta catirina micro-forms. the first is characterised by uncovered karren fields that have been developed under soil cover. soil has probably been washed away since the early 20th century, when intense deforestation changed the natural landscape of monte albo. at punta catirina, especially along the north-eastern slope, rillenkarren, kamenitze and solution channels are relatively well preserved, representing a good didactic example of small scale karst landforms. similar in shape but located on the other extremity of the chain is punta cupetti from where the entire morphology of monte albo can easily be understood. punta cupetti is also characterised by the presence of rich micro-forms sculpted in the s’adde limestones. many caves have been inserted in the database: conca ‘e crapa, su santuariu, omines agrestes and listincu caves are horizontal relics of an ancient underground and complex karst drainage system. while omines agrestes and galleria listincu are small caves (dore et al., 1996), formed by karst solution along fissures, conca ‘e crapa and su santuariu are much more complex and important testimonials of ancient karst processes. conca ‘e crapa is one of the highest caves of sardinia (1050 m a.s.l.), composed of several chambers connected by crawling passages (dédé, 1976; loru & sechi, 1984), and represents a very important habitat for cave dwelling fauna (grafitti, 1996). su santuariu, instead, is located almost 1000 meters lower and is characterised by the presence of massive and important concretions (dore et al., 1996), probably testimonials of a much wetter and warmer climate. at even lower altitudes, at the foot of the mountain, two active caves are classified as geomorphosites; the cane gortoé and the locoli resurgences. the first, located in the centre of the village siniscola at an altitude of 40 m a.s.l. has a development of almost 1000 meters and is very important for its cave dwelling fauna (grafitti, 1996). cane gortoé contains two slowly flowing underground rivers that meet just before exiting the cave and represents the active base level of the karst acquifer of monte albo (mucedda, 1991). locoli instead has a much more impressive appearance and becomes active only after heavy rain periods. this cave, of great hydrogeological importance (maccioni, 1976; murgia, 1999) is located at an altitude of 100 m a.s.l. and has an important underwater development explored during the 80’s by french cave divers (le guen, 1983; pittalis et al., 1983; isler, 1990). the total at present explored development of this cave system reaches more than 1500 meters (perna & murgia, 2002). the underground river that exits the mountain from the locoli cave is believed to come from the bonaettè sinkhole, located at a distance of approximately 4 km wnw at an altitude of 550 m a.s.l. (sanna, 1990). this sinkhole, although not very beautiful and active only after heavy rains, is nevertheless one of the most didactic ones of the monte albo chain, and for its hydrogeological importance this swallow hole deserves its classification as geomorphosite. the current main outflow from the monte albo aquifer is located close to siniscola, near the san giuseppe chapel, and has been known since a long time as the san giuseppe or fruncu ‘e oche spring. this karst spring, with a mean discharge of 80 l/s, is developed on important fault systems at an altitude of 48 m a.s.l. (perna & murgia, 2002). to explain further geological interest of monte albo four non-karstic geomorphosites have been chosen: the geological and tectonic features of punta azza ruja, the punta gutturgius palaeo-landslides, the cuile su ramasinu overthrust with outcrops of the cuccuru ‘e flores conglomerates and the impressive vertical cliffs of the north-western side of the monte albo chain. at punta azza ruja, in the southern part of the carbonate chain, a thick succession of basal dolomite beds dipping southeast clearly shows overthrusting and faulting, while at the foot of punta gutturgius early-quaternary landslides have determined unusual landforms with impressive isolated dolomite blocks. near cuile su ramasinu, instead, overthrusting has enabled the preservation of the eocene cuccuru ‘e flores conglomerate, important testimony of the cretaceous erosion period. 5. conclusions monte albo is an important landscape unit that constitutes a characteristic landmark in the northeastern part of sardinia. landforms are mainly related to karst processes and subordinately to tectonic features. the twenty-three geomorphosites described in this paper represent most of the morphological processes 151karst geomorphosites ... that this mountain went through in the past millions of years. the connection of these geomorphosites in a local network, comprising the realisation of equipped pathways and the elaboration of explicative maps and panels and a website in which geology, geomorphology, karst, fauna, flora, archaeology and industrial archaeology are described, would be an interesting alternative to the conventional tourist offer of this region based on beaches and one-day trips to single tourist sites (nuraghi, show caves etc.). in fact, the explanation of the landscape, its evolution, its geodiversity and the single elements it contains can help the visitors in understanding the importance of geology and geomorphology on landscape evolution, biology and human activities, that combine in an educational model of great suggestion and efficiency. this valorisation fits also well in the framework of the geomining, historical and environmental park of sardinia of which the monte albo landscape unit, comprising the two abandoned mines of guzzurra and sos enattos, is part (area number 6). furthermore, the evaluation of the geological and geomorphological heritage of monte albo enriches the classification of the area on a pure biological basis (cassola & tassi, 1973) and as a site of comunitary interest (directive habitat 92/43, sic itb001107). this proposal of valorisation of these landscapes and geomorphosites could well be connected to other areas of the region, and the authors hope that the local and regional stakeholders will participate in the valorisation of their territory, giving an important service to the many tourists that come and visit the monte albo acknowledgements this study has been carried out in the framework of the national project cofin 2001-2003 “geomorphosites in the italian landscape”, national coordinator prof. sandra piacente of the university of modena, responsibles of the local research unit prof. antonio ulzega and prof. felice di gregorio of the university of cagliari. the comments of the two referees, leonardo piccini and marco firpo were helpful to enhance this paper. references altara e. 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(1997) tertiary transcurrent tectonics of north-central sardinia bull. soc. géol. france, 168, pp. 301-312. perna g. & murgia f. (2002) il carsismo profondo messiniano in sardegna: prospettive per la ricerca di acque profonde in: j. de waele (ed.), il carsismo e la ricerca speleologica in sardegna, anthèo, 6, pp. 107-124. piccini l., sauro u., de waele j. & mietto p. (2004) the italian register of natural hypogean geosites: a preliminary report proceedings of the workshop "geomorphological sites assessment and mapping", cagliari 1-5 ottobre 2003 il quaternario (this volume) (in print). pittalis g., penez p. & chouquet j.c. (1983) spedizione alla grotta di "locoli" gruttas e nurras, pp. 12-13. sanna f. (1990) ipotesi dell'esistenza di una grotta a bonaettè (monte albo) gruttas e nurras, pp. 2021. 153karst geomorphosites ... imp.ruberti& inventory of the geopalaeontological heritage in protected areas of the campania apennines daniela ruberti1°, marco vigliotti1, giuseppe sirna2 & maurizio muselli1 1dipartimento di scienze ambientali, seconda università degli studi di napoli (caserta). e-mail: daniela.ruberti@unina2.it 2via primo acciaresi, 15 – 00157 roma ° “centro regionale di competenza per lo sviluppo ed il trasferimento dell’innovazione applicata ai beni culturali ed ambientali”, u.o. 2 (sviluppo ed applicazioni di metodologie e tecnologie scientifiche avanzate per lo studio ed il monitoraggio dei beni culturali e ambientali), wp 2.4 (laboratorio integrato per il monitoraggio della qualità ambientale) abstract: d. ruberti et al., inventory of the geopalaeontological heritage in protected areas of the campania apennines. (it issn 0394-3356, 2005). goal of the present paper is to select important geopaleontological sites in protected areas of the campania apennines by constructing a geosites database. in particular, following research activities focused on cretaceous rudist benthic communities, areas where fossiliferous horizons occur rich in rudists have been selected. these organisms were widespread in shallow marine settings during the cretaceous time and become extinct at the end of that period. the wide distribution of the rudists during the cretaceous makes them an usefull key to evaluate the paleoecological and sedimentary conditions of the environments they colonized. their study may provide interesting qualitative insight in palaeoecological dynamics of carbonate platforms. geopalaeontological sites from protected areas of the campania apennines have been recognized and listed in order to promote the knowledge of the geological history of these regions not only among specialists. a computerised database of the selected geopaleontological sites has been created on the base of the italian geological survey indications. tabeled data have been imported in a gis project that also contain the administrative boundaries and the limits of regional/national parks and protected areas. other tematic database can be linked to the gis project. such a recognition and inventory may offer a way to make use of such an heritage through naturalistic routes that evidence the geological history of a region. riassunto: d. ruberti et al., censimento del patrimonio geopaleontologico nelle aree protette dell’appennino campano. (it issn 0394-3356, 2005). scopo del presente lavoro è quello di selezionare importanti siti geopaleontologici in aree protette degli appennini campani attraverso la costruzione di un database dei geositi. in particolare sono state selezionate, sulla base delle attività di ricerca sulle comunità bentoniche delle rudiste del cretaceo, aree con orizzonti fossiliferi ricchi in rudiste. questi organismi erano abbandonati nei fondali marini bassi durante il cretaceo e si estinsero alla fine di questo periodo. l’ampia distribuzione di rudiste durante il cretaceo le rende un utile strumento per valutare le condizioni paleoecologiche e sedimentarie degli ambienti che hanno colonizzato. il loro studio può fornire interessanti indicazioni delle dinamiche paleoecologiche delle piattaforme carbonatiche. sono stati riconosciuti ed elencati siti geopaleontologici di aree protette dell’appennino campano con lo scopo di diffondere la conoscenza della storia geologica di queste regioni anche in un pubblico di non specialisti. sulla base delle indicazioni del servizio geologico nazionale si poi è proceduto alla creazione di un database dei siti geopaleontologici selezionati. i dati raccolti nel database sono stati inseriti in un gis, contente anche i confini amministrativi e i confini dei parchi nazionali, regionali e delle aree protette. altri database tematici possono essere collegati al gis. questo censimento può rappresentare un valido strumento di valorizzazione di questo ricco patrimonio attraverso sentieri naturalistici che mettano in evidenza la storia geologica della regione. keywords: geopalaeontological sites; cretaceous; rudists; southern apennines. parole chiave: siti geopaleontologici, cretaceo, rudiste, appennino meridionale. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 125-136 1. introduction carbonate deposits, that form most of the central-southern apennines, testify to a long and complex geological history. moreover, since carbonates are the direct result of biosphere metabolism, it is important to understand the role played by the biosphere in controlling sedimentation and evolution of carbonate bodies. the genesis and evolution of the latter thus represent the key to recognize changes in climate, oceanic circulation, relative sea level changes, etc., that have affected the development of depositional systems and the delicate biological equilibria of benthic communities, considered as primary carbonate sediment-producers. cretaceous deposits, widespread in the centralsouthern apennines, are particularly interesting. in general, they appear to have originated in shallow water marine environments in which benthic communities (mostly composed by molluscs – bivalves and gastropods – benthic foraminifers, bryozoans and red algae) settled. their study has been fundamental in reconstructing shortand long-term environmental changes (cf. carannante et al., 1995; 1997; 1999; ruberti, 1997; simone et al., 2003, and references therein) and still 126 d. ruberti et al. involves international research groups. among the benthic communities, in particular, rudists (a group of invertebrate metazoa) represent an interesting and complex case history. these organisms, which appeared at the end of the jurassic and lived till the end of the cretaceous, were found throughout the shallow water environments of the old tethys ocean, from its inner shelf to marginal environments. their rapid evolution, as well as their great species diversity, makes them good stratigraphic markers for the cretaceous and a valuable tool to evaluate the paleoecological and sedimentary conditions of the environments they colonized and the factors that controlled their evolution and extinction. at this regard, within the international union on geological sciences (iugs), the cretaceous research working group 4 (crer wg4) and the international research group on rudists have promoted interesting international activities (conferences, scientific volumes, field seminars) focused on cretaceous bioconstructions through time and space (simo et al., 1993; cestari & sartorio, 1995; masse et al., 1995; proceedings of the 2nd, 3rd, 4th, 5th, 6th intern. conference on rudists) in order to provide qualitative insight in palaeoecological dynamics of carbonate platforms. this kind of study has highlighted very descriptive, spectacular, well exposed outcrops, which are wellsuited to becoming geopalaeontological sites of natural interest. in recent years, national institutions (i.e. national geological survey, enea), local administrations, international associations (iugs, progeo) and earth science societies have started to promote geological culture outside the usual specialists. a proposal of a geosite inventory has been proposed to the international earth science communities, especially since the birth of progeo italia, with a view to selecting an international list of the most important sites for geological sciences and identifying what is special and representative in the geology of each country (cf. praturlon, 1996; wimbledon et al., 1996; brancucci et al., 1999; wimbledon, 1999; d’andrea, 2000). it is thus particularly important that public administration converges with the world of geological and environmental research to ensure an increasingly attentive approach to renewable and non-renewable natural resource management. the latter may also be achieved by protecting sites of particular geo-palaeontological interest in the regions concerned. the aim of the present paper is to select the most important geopalaeontological sites in protected areas of the campania apennines by constructing a geosites database. such a recognition and inventory may open up the possibility of exploiting such resources sustainably by mapping out trails that highlight the geological history of the region. 2. rudists rudists are bivalves with more or less modified shells. they can be divided into two groups: those attached by the right valve (monopleura , caprina, hippurites, radiolites genera, among others) and those attached by the left valve (requienia, toucasia genera). during their evolution, rudists were subjected to major changes as a response to ecological factors (fig. 1; based on sirna & laviano, 1989; sirna, unpublished data; see also cestari & sartorio, 1995). the earliest rudists (diceratidae) were only slightly inequivalve genera, the latter characteristic becoming increasingly pronounced. requieniidae evolved at the beginning of the cretaceous from the diceratiidae and were characterized by an inequivalve left valve, attached to the substratum. the right valve was smaller, opercular. the presence of an external ligament caused an accentuated tangential shell growth and the consequent spirogyrate shell-shape (cestari & sartorio, 1995). the ligament invagination produced the uncoiling and rising from the substratum of the shell, as can be observed in the caprotinidae and caprinidae. the latter had an inequivalve shell that reached also wide dimensions. the right fixed valve was small and conical while the left free one was more developed and markedly spirogyrate. the shells of radiolitidae and hippuritidae changed their architecture gradually, achieving a pipe-like shape with an opercular upper valve. in evolutionary terms, radiolitidae are older than hippuritidae; both reached their peak expansion with marked endemism during the late cretaceous. similarly to other important organisms, these bivalves did not survive the great mass extinction that occurred at the end of the cretaceous. 2.1 palaeoecological aspects among the cretaceous sediment producer organisms, rudists play an important role because they occurred in different depositional environments of the tethys ocean. they spread over the carbonate shelves, from the innermost settings to the outermost sectors of the shelf. their rapid evolution and large number of species make rudists good stratigraphic markers in the whole carribean and mediterranean region (cf. pons & sirna, 1992; cestari & sartorio, 1995; sirna & paris, 1999; proceedings of the 2nd, 3rd, 4th, 5th, 6th intern. conference on rudists; among others). they are known from the gulf of mexico, iberian peninsula, southern france, the italian apennines, apulia, the dinarides, romania, hungary, poland, greece, turkey, syria, the lebanon, and north africa. during the cretaceous, rudists inhabited tropical and subtropical belts of the tethys, including those between north and south america and the indopacific. a few highly specialized taxa (mostly radiolitidae), settled in the temperate zones of southern canada and the british isles. as already stated, rudists preferred the neritic realm, adapting to different kinds of sea bottoms: some genera colonized sandy bottoms, others preferred silty-sandy ones, at least the terrigenous ones. nevertheless, as a rule rudists preferentially inhabited carbonate environments. more generally, the main observation is that from the middle-upper cretaceous, rudists spread over all shelf sectors, from more open and external areas to more internal ones, occupying different substrata and furnishing the bulk of the skeletal component by means of bioerosion processes. they colonized mobile sediments giving rise to complex bodies with peculiar characteristics related to the environmental parameters of the different sectors of the shelf (cf. carannante et al., 2001; simone et al., 2003). 2.2 rudists of the southern apennines during the lower cretaceous, the requienidae and caprotinidae are the best represented. the former preferred sheltered environments, characterized by fine-grained, mainly muddy substrata, such as protected lagoons, and only occasionally they can be found associated with silty-sandy sediments. caprotinidae and caprinidae assemblages are common in higher energy environments, such as open shelves (well known in the matese, southern fucino campoli appennino and monti d’ocre successions). nevertheless, owing to vast and complex geologic events occurred in the late aptian-early senonian time (e.g. changes in climate, oceanographic circulation, sea level, tectonic and volcanic activity), the cretaceous carbonate platforms modified the organization of their depositional system resulting in a drastic facies variation. in particular, during cenomanian time, the eustatic oscillations and tectonic events that interested the periadriatic region induced localized emersions and strong physiographic alterations of the carbonate 127inventory of the geopalaeontological ... platforms. even the carbonate platforms of centralsouthern italy were affected by these events. in their evolution it is possible to recognize crisis period in rudist evolution that started during the albian and that was characterized by a decrease of species, genera and family number. an abrupt inversion of tendence is recorded in the lowermost cenomanian through an adaptative radiation of forms and an increase of the biological diversity mainly in the high energy and/or marginal open areas of the shelf. in the cenomanian time carbonate shelves became more articulated, owing to the complex tectonic and eustatic events that characterized the periadriatic region. in this interval several genera of caprinidae developed, in association with radiolitidae and a few corals, especially in the outermost sectors of the shelf. in more protected settings gastropods (nerineids) and radiolitid assemblages flourished togheter with oysters (chondrodonta) and benthic foraminifers. at the end of the cenomanian, in correspondence of the turonian boundary, a new important crisis phase took place in all shallow-water environments. this one knocked mainly the caprinids, among the rudists, but also nerineans, and only few species of them survived. during the upper turonian-senonian interval, rudists spread over all the shelf sectors, from more fig. 1 – evolution of the main rudist families and their distribution in time (based on cestari & sartorio, 1995, and bosellini, 1991). see text for explanations. evoluzione delle principali famiglie di rudiste e relativa distribuzione nel tempo (modificato da cestari & sartorio, 1995, bosellini, 1991). per ulteriori spiegazioni si veda il testo. 128 open and external areas to more internal ones, occupying different substrata and furnishing the bulk of the skeletal component. rudists grew in loose sediments giving rise to limited and scattered rudist-rich bodies. stormand wind-induced currents and waves repeatedly mobilized the rudist-supporting loose sediments; as a consequence toppled shells are very abundant and only in the more internal and protected shelf sectors, the growth-related arrangement of the rudistshells can be easily observed (cf. carannante et al., 1993; 1997; simone et al., 2003). 3. inventory of the geopalaeontological heritage 3.1 identification and inventory of sites of palaeontological importance rudist-bearing cretaceous successions cropping out in the southern apennines have been intensively studied in recent years (cf. § 1) on the basis of research projects dealing with the environmental reconstruction of the cretaceous carbonate platforms and the recognition of the factors influencing growth and development of the biotic communities, primary sediment producers (cf. simone et al., 2003, for a review). particularly interesting, spectacular geopalaeontological sites have been recognized, that can be proposed for preservation. some sites lie within protected areas of campania. two sites are illustrated herein, located in the widest protected areas of the campania region: the matese and cilento mountains (fig. 2). the main purpose is to evidence the geopalaeontological aspects of international importance and make them known through a computerized inventory in order to include the sites along specific nature trails. 3.1.1 regional park of matese the matese mountains represent the eastern part of the southern apennines and straddle the provinces of benevento, isernia, campobasso and caserta. the matese mountain range morphologically forms one of the main axial culminations of the southern apennines (fraissinet & la valva, 2001). it derives from the deformation of a palaeogeographic domain characterized by a carbonate sedimentation from the triassic to the lower miocene, with local and sometimes large stratigraphic gaps. the sedimentary model for the mesozoic is a carbonate platform with scarps of variable inclination and height that came into existence in the upper trias and was deformed by the late miocene tectogenetic events and dissected by plio-pleistocene tectonics. the main outcrops concern the mesozoiccenozoic shallow water-to-slope carbonate platform domain pertaining to the southern tethys. the outcrops relative to transitional facies between these two domains are poorly defined, with no physical continuity and are strongly tectonized. rich and interesting fossiliferous “horizons” are found throughout the mountains, culminating in the real “subaerial museum” of pietraroia. they offer an interesting record of the meso-cenozoic marine life and environments. cretaceous deposits appear particularly interesting: they record the events that characterized the periadriatic region in that period (d'argenio, 1974; channel et al., 1979; d'argenio et al., 1980; radoicic, 1987; accordi & carbone, 1988; cocco & d'argenio, 1988; carannante et al., 1991; d'argenio & mindszenty, 1992; carannante et al., 1994) and show remarkable facies differences in various matese sectors. shallow water deposits characterize the whole cretaceous eastern matese successions, while in the western area late cretaceous margin-to-slope bioclastic limestones d. ruberti et al. fig. 2 – location map of the proposed gepaleontological sites. a) serra delle macchietelle hill, in the regional park of the matese mounts. b) trentinara outcrop in the national park of cilento and vallo di diano. igm topographic map 1:50000, sheet 405, 487, 503. ubicazione dei siti geopaleontologici proposti per la tutela. a) dorsale di serra delle macchietelle, nel parco regionale del matese. b) affioramento di trentinara, nel parco nazionale del cilento e vallo di diano. basi topografiche igm, in scala 1:50000, fogli 405, 487, 503. 129 (better known in the literature as "calcari pseudosaccaroidi bianchi" or "calcari cristallini” selli, 1958; pescatore, 1964; 1965; ietto, 1970; accordi et al., 1982) can be recognized resting on triassic-jurassic shallow water limestones. stratigraphic analysis carried out in this region led to identify in the eastern area the source of sediments accumulating in the western area. the sector proposed for protection comprises the central part of the matese mounts, around the lake of matese, on the southern flanks of m. miletto. this area is characterized by mesozoic shallow-water limestones. cretaceous limestones are well exposed, characterized by large occurrence of rudist facies that represent highly didactic successions, both for scientific and naturalistic/touristic purpose (accordi at al., 1990; ruberti, 1991; carannante et al., 1993; 1997). 3.1.2 national park of cilento and vallo di diano the national park of cilento and vallo di diano is the second largest national park in italy (181,048 ha) and represents one of the largest biogeographic complexes in southern italy. its geographical position, the coasts, the rivers, and the mountains have resulted in a variety of environments. geologically, the area is characterized by limestone mountains in the eastern part, with the alburni range and mt. cervati, and arenaceous reliefs in the western part (mt. stella, mt. sacro, mt. centaurino); the southwestern part is once again limestone (mt. bulgheria). by a geomorphological point of view, the cilento park consists of both smooth hills and high mountains. long, deep valleys cut the mountain flanks; the rivers running over them gave rise to wide and smooth alluvial areas. moreover the cilento has the most extensive karstic system in the southern apennines. by a geopalaeontological point of view, the limestones cropping out in this area offer rich and interesting fossiliferous “horizons” that document mesocenozoic marine and fresh-water life and environments. the sector proposed for protection comprises the mt. soprano-mt. vesole structures and the monti alburni. this area has outcrops of great importance for geopalaeontological studies, which testify to the geological history of the region. the mt. soprano-mt. sottano ridge is a 20 km nw-se belt that crops out south of the sele plain and represents the northern margin of the cilento mountains (cestari, 1971; sgrosso, 1968). this structure may be considered part of a wide anticline pertaining to the stratigraphic-structural unit of alburno-cervati (scandone, 1967; sgrosso, 1968; d’argenio et al., 1973). mesozoic lithologies cropping out in the studied area mainly consist of carbonate platform limestones and, subordinately, dolostones pertaining to the campano-lucanian carbonate platform succession (scandone, 1972; d’argenio et al., 1973) of the upper triassic-to-senonian age. a transgressive palaeocenemiocene succession overlies in paraconformity the upper cretaceous successions. the cretaceous sediments, in particular, were deposited in shallow-water environments that show a change from restricted circulation and tidal settings during the early cretaceous to more open marine conditions in the late cretaceous (cestari, 1971). previous stratigraphic studies have been carried out by sartoni & crescenti (1963), scorziello & sgrosso (1965), sgrosso (1968) and cestari (1971). 3.2 inventory of geopalaeontological data the data were catalogued through computerized inventory tables, created on the basis of the italian geological survey indications (cf. praturlon, 1996; wimbledon et al., 1996; brancucci et al., 1999; wimbledon, 1999; d’andrea, 2000). the microsoft access 97 database was developed with several tables bearing homogeneous information (fig. 3): • geosite identification data (e.g.: country, town, province, locality, utm coordinates, height above sea level, etc.) • geosite quality (scientific importance, interest, state of preservation, etc.) • geological data (e.g.: lithology, age, age of the substratum, etc.) • palaeontological data (e.g.: biotic remains, icnite, etc.) • accessory data (degree of knowledge, presence of areal constraints, etc.) • selected references each table is related to the others through a common field (“num. progressivo”; fig. 4) which allow the unique identification of the geosite through simple queries. each table corresponds to a mask (fig. 5) created with the purpose of reducing data entry mistakes, displaying all the indications to fill in the tables, and showing indicative schemes and pictures. these tables represent a database that can be read in ms access environment and imported in a gis project. a gis prototype was created; the geopalaeontological sites are located as spots on a georeferenced topographic map (sheet 1:50.000 igm, 50/l series, 3 colors), in raster format (fig. 6). the project also contains the administrative boundaries and the limits of regional/national parks and protected areas, as indicated under law 394 of 6.12.1991 and regional law 33 of. 1.9.1993. in particular, for the proposed sites, the zones of integral reserve (zone a), general reserve (zone b) and controlled reserve (zone c) are delimited. the project was set up with geomedia pro of intergraph corporation and published on the web site of the dipartimento di scienze ambientali of the seconda università degli studi di napoli (www.sa.unina2.it). 4. description of the proposed sites as an example, one site was selected from the national park of cilento and vallo di diano and one from the regional park of matese. 4.1 regional park of matese: the serra delle macchietelle outcrop the proposed site is represented by the serra delle macchietelle hill, located at the northwestern end of the matese lake (fig. 2). serra delle macchietelle is a nw-se hill rising from the lake up to 1202 m above sea level. it is mainly made up of ne dipping limestones, well exposed along the southern flank road cut, from nw toward se (ruberti, 1991, 1992; carannante et al., inventory of the geopalaeontological ... 130 d. ruberti et al. fig. 3 – tables from the ms access 97 database concerning identification data, geological data, paleontology, geosite quality. esempi di tabelle relative al database creato in ms access 97, riferite ai dati identificativi, geologici, paleontologici e alle qualifiche del sito. 1993). early cretaceous deposits are rich in bivalves (among which requienidae and oysters), gastropods (mostly nerineids), giving rise to thick beds cyclically alternating with loferitic and stromatolitic limestones (fig. 7a, c). up in the sequence, thanatocoenosis rich in radiolitidae and caprinidae constitute small congregations (sensu gili & skelton, 2000; see also ruberti & toscano, 2002) associated with oysters and gastropods (fig. 7b). the upper cretaceous is characterized by widespread distribution of radiolitidae, locally forming well preserved assemblages supported by bioclastic sands (fig. 7d). the related lithosomes result to be delimitated and often eroded by coarse sandy deposits in which it is possible to recognize transported organisms which are often still undamaged. these lithofacies (mollusc rudstones-floatstones in a matrix of silty packstones) are generally found in more or less silt-rich lens-shaped bodies, which contain a great abundance of poorly sorted bioclastic material. the resulting rudist-rich bodies, that may be 3-10 m thick and for a few tens of meters in diameter, laterally blend into bioclastic talus in which it is common to find cross-lamination, graded beds, isorientation and imbrication of the grains. many bioclastic episodes clearly appear to have originated from storms, on the basis of associated sedimentary structures; others represent the normal breakdown of the organisms which grew developing limited positive structures, with more or less intensive reworking of the grains. deposition, therefore, took place on shelf areas on relatively shallow sea floors which might be periodically exposed, thereby undergoing dissolution phenomena. 4.2 national park of cilento and vallo di diano: the trentinara outcrop the proposed site is located in the northern margin of the cilento, nearby the village of trentinara (fig. 2). the road cut along the southern flank of mt. vesole, starting from the madonna di loreto sanctuary, shows fine outcrops characterized by subhorizontal calcareous strata in which well-preserved rudist-beds offer a bidimensional picture of cretaceous sea beds. detailed taphonomic studies (ruberti & toscano, 2002; carannante et al., 2003) have shown the species distribution in the various fossiliferous beds and the different spatial arrangement of the sedimentary bodies that range from monospecific biostromes to subtidal channelized bodies in which rudists have been found to colonize channel levees. taphonomic characterization enabled hydrodynamic control on lithosome evolution, geometry and spatial distribution to be recognized. the rudist shell beds are characterized by low species diversity, with slight differences in the abundance of a few species belonging to the durania, bournonia, sauvagesia, gorjanovicia and biradiolites genera, that usually form oligoor monospecific con131inventory of the geopalaeontological ... fig. 4 – relationships among tables in the database. esempio di relazioni tra tabelle nel database relazionale creato. 132 d. ruberti et al. fig. 5 – examples of masks supporting the tables in the database. esempio di m a s c h e r e create per l’inserimento dati nel d a t a b a s e realizzato. fig. 6 – screenshot of the gis prototipe created with geomedia 4.0 pro (intergraph) to read the database on the georeferred map. cattura a video del progetto gis realizzato con geomedia 4.0 pro (intergraph) per la visualizzazione su basi cartografiche georiferite delle banche dati relative ai geositi. gregations (fig. 8). the characteristics of the shell beds show, in the first instance, that the recognized rudist species settled and thrived in relation to the grain size and the hydrodynamics, giving rise to different lithosome composition and geometry. the taphonomic attributes of macrofossil associations were broadly categorized on the basis of carannante et al. (1998; 2000) and ruberti & toscano (2002). the internal fabric of these levels (i.e. orientation, arrangement, packing and sorting of the skeletal elements; internal microstratigraphy) allowed two broad shell bed categories to be distinguished: a) shell beds considered as “primary shell concentration” in which the shell concentration is essentially created by the behaviour of local shell producers, preserved in situ and in growth position; b) shell beds considered as “hydraulic shell concentration”, that were deposited under the influence of hydraulic processes and/or input of surrounding bioclastic sediments. all the aspects described, in terms of lithofacies associations, taphonomic aspects of the rudist congregations and their role in the depositional cycles, testify to open shelf settings periodically disturbed by higherenergy events. the latter might have resuspended finegrained sediments and caused the benthos to become unstable, though the fine fractions settled down in situ. the depositional sites were characterized by a large-scale facies polarity. under closer examination, a patchy distribution of the latter appears, often related to channelized systems or current pathways through rudist settlement areas. 5. concluding remarks knowledge and the subsequent census of the geological heritage of a region undoubtedly constitute very important elements for local administration (gisotti & massoli-novelli, 1997; zarlenga, 1996; d’andrea & di leginio, 2002), even if the motivation behind them may be simply knowledge-oriented. the value of such heritage can be enhanced by creating itineraries that highlight the geological history and dynamics of the region. indeed all regional protected areas have a large potential for tourism which has to be organised intelligently. the key to such tourist development is diversification which allows, amongst other things, a broader yearround distribution of tourist flows. hence the importance of targeting school tourism and cultural tourism in general, which is particularly busy in autumn and spring, creating a network of footpaths that allows direct observation of the area’s geological and palaeon133inventory of the geopalaeontological ... fig. 7 – serra delle macchietelle outcrop. a) close-up of a nerineid specimen. b) thicket formed by caprotinidae, closely-spaces in an upright growth position. c) floatstone rich in chondrodonta sp. and gastropods (among with acteonids and nerineids). d) radiolitid limestones. affioramento di serra delle macchietelle. a) dettaglio di un esemplare di nerineide. b) thicket formato da caprotinidi, addensate e in posizione di crescita. c) floatstone ricco in chondrodonta sp. e gasteropodi (tra cui acteonidi e nerineidi). d) calcari a radiolitidi. tological heritage is effective way to conserve and protect its cultural and natural assets. acknowledgements we thank l. simone and g. carannante (university of naples) for helpfull discussion. this contribution present results from research projects supported by italian research ministery (prin 2000 and 2002; responsible d. ruberti) and second university of naples (ex 60% founds to d. ruberti) and has been based on unpublished data of g. sirna. d. ruberti took care with sedimentological and taphonomic aspect; m. vigliotti took care of the gis project and the database organization; m. muselli realized and implemented the computerized database. the authors acknowledge a. russo and an anonymous reviewer for their thoughtful suggestions and comments. references accordi g. & carbone f. 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(1996) i geotopi, dalla ricerca scientifica alla pianificazione, controllo e gestione geologia dell’ambiente, vol. 4/2, pp. 3-6. 136 d. ruberti et al. imp.ciaranfi_calabriano il piano calabriano neri ciaranfi1*, enrico di stefano2, fabrizio lirer3, patrizia maiorano1, maria marino1, domenico rio4, rodolfo sprovieri2, simona stefanelli1 & gianbattista vai5 * autore corrispondente <neri@geo.uniba.it> 1dipartimento di geologia e geofisica, università di bari 2dipartimento di geologia e geodesia, università di palermo 3iamc-cnr, napoli 4dipartimento di geologia, paleontologia e geofisica, università di padova 5dipartimento di scienze della terra e geologico-ambientali, università di bologna. abstract: n. ciaranfi, e. di stefano, f. lirer, p. maiorano, m. marino, d. rio, r. sprovieri, s. stefanelli & g. vai, the calabrian stage. the proposal of using the calabrian stage to indicate the lower pleistocene has been accepted by international community of quaternary scientists: the base of this stage is coincident with the gssp in the vrica section in calabria, almost coincident with the top of olduvai paleomagnetic event at 1.81 m.y. b.p. the top of the calabrian stage is conventionally located at the matuyama-brunhes magnetic reversal, whose age is 0.78 m.y. b.p. the stratigraphic interval of the calabrian is almost fully exposed in several stratigrahic sections outcropping in southern italy: in particular calabria and sicily land sections show the lowest portion of the stage, including the gssp; the youngest part of the calabrian succession is well represented in two stratigraphic sections in crotone area and in the southern apennine foredeep (lucania basin). the same stratigraphic interval has been drilled in several odp sites in southern thyrrenian and jonian seas. parole chiave: quaternario, depositi marini, cronostratigrafia. keywords: quaternary, marine sediments, chronostratigraphy. il quaternario italian journal of quaternary sciences 21(1a), 2008 23-28 il termine calabriano, introdotto nella letteratura geologica da gignoux (1910), è stato usato a lungo per indicare l’intervallo stratigrafico più antico del quaternario: come tale compare nelle scale cronologiche di berggren & van couvering (1974), di haq & eysinga (1987). dopo l’approvazione del gssp del limite pliocene/pleistocene nella sezione di vrica in calabria (inqua, 1982; iugs, 1984), l’uso del termine calabriano, a causa della diacronia fra la base del calabriano, nella località indicata da gignoux, ed il gssp del pliocene-pleistocene di vrica, fu progressivamente abbandonato da numerosi stratigrafi italiani. questi ultimi, per indicare la porzione inferiore del quaternario, proposero di suddividere il pleistocene inferiore – complessivamente denominato selinuntiano (ruggieri & sprovieri, 1979) – utilizzando e rivisitando tre unità cronostratigrafiche già antecedentemente definite: santerniano (ruggieri & sprovieri, 1975), emiliano (ruggieri & selli, 1949) e siciliano (doderlein, 1872). questa nomenclatura, seppur largamente accettata ed utilizzata dalla comunità scientifica italiana, non ha però ricevuto alcuna formalizzazione dalla commissione internazionale di stratigrafia dell’iugs; a livello internazionale si è proseguito ad usare il calabriano per indicare il pleistocene inferiore, come è stato recentemente ribadito da g i b b a r d et al. (2005) nella global chronostratigraphic correlation table presentata nel 2004 al congresso geologico internazionale di firenze. la commissione italiana di stratigrafia, sotto la guida di m.b. cita, a partire dal 1994, si è prefissa l’obiettivo di standardizzare la nomenclatura delle suddivisioni stratigrafiche delle successioni sedimentarie marine del quaternario (cita & castradori, 1994); con questo scopo ha proposto la definizione dei piani marini del pleistocene inferiore (calabriano), medio (ioniano) e superiore (tarentiano) in mediterraneo (cita et al., 2006). la formalizzazione del calabriano, che rappresenta il piano più antico della serie pleistocenica, è contenuta in una nota sottoposta alla stampa su episodes nel settembre del 2007 (cita et al., in press): il dibattito su questo tema è avvenuto nel corso del workshop tenutosi a rimini (fist 2007) e la proposta è stata unanimemente accettata. la base del calabriano è posta in coincidenza del gssp del pleistocene nella sezione di vrica (calabria), al tetto del livello sapropelitico e (età 1,806 ma, lourens et al., 2004), al passaggio tra gli stadi isotopici 65 e 64, circa a tetto dell’evento paleomagnetico olduvai a 1,81 ma b.p. il suo tetto è proposto in corrispondenza dell’inversione paleomagnetica matuyama/brunhes, a 0,78 ma b.p., in coincidenza con la base del sovrastante piano ioniano (cita et al., in press). la scelta di usare parametri fisici come le inversioni di polarità magnetica per individuare i limiti di piani, operata dalla comunità scientifica internazionale, è motivata dalla facilità di identificazione di questi limiti isocroni sia in successioni costituite da sedimenti marini, che rappresentate da depositi continentali, rendendo così più agevoli le correlazioni tra ambienti diversi anche a livello globale. il record sedimentario marino del pleistocene inferiore, è stato oggetto di numerosi studi condotti da dif24 ciaranfi et al. ferenti aa. sui depositi pelagici affioranti in varie località del crotonese e di diverse aree siciliane (selli, 1967; selli, 1970; pasini et al., 1975; pasini & colalongo, 1982; aguirre & pasini, 1985; bassett, 1985; hilgen, 1991; sprovieri, 1993; van couvering, 1995; lourens et al. 1996; rio et al., 1996a; 1996b; vai, 1996; 1997; lourens et al., 2004; cita et al., 2006; cita et al., in press), come anche su successioni sedimentarie marine rappresentative della parte alta del pleistocene inferiore al passaggio con il pleistocene medio (c i t a & castradori, 1994; 1995; ciaranfi et al., 1996; ciaranfi et al., 1997; ciaranfi et al., 2001; d’alessandro et al., 2003; maiorano et al., 2004; capraro et al., 2005; stefanelli et al., 2005). la massima parte delle sezioni a terra (vrica, le castella, s. maria di catanzaro, singa, monte s. nicola e capo rossello, santerno e stirone) (fig. 1), storicamente rappresentative del pleistocene inferiore, contiene solo una parte della successione calabriana, con intervalli stratigrafici di vario spessore tutti caratterizzati dall’affiorare della base di questa unità cronostratigrafica. la parte superiore del calabriano è rappresentata nelle sezioni siciliane della valle del belice e di ficarazzi, che però mancano della parte più recente dell’unità cronostratigrafica, e da due sezioni (valle di manche nel crotonese, montalbano ionico nella parte meridionale dell’avanfossa appenninica, in basilicata) nelle quali è invece esposto il tetto del calabriano unitamente alla base del sovrastante ioniano. l’intervallo calabriano è stato attraversato in numerose carote recuperate nel mediterraneo (odp leg 107, 160, 161, carota kc01b) alcune delle quali sono rappresentate in fig. 1. gran parte delle sezioni a terra ora ricordate, come pure tutte le carote odp, sono state sottoposte ad accurate indagini biostratigrafiche a plancton calcareo (foraminiferi e nannofossili), di stratigrafia isotopica dell’ossigeno, stratigrafia a sapropel, tefrostratigrafia, magnetostratigrafia e di ciclostratigrafia orbitale (rio et al., 1990a, 1990b; castradori, 1993; lourens et al., 1996a; 1996b; 1998; sprovieri et al., 1998; di stefano, 1998; howell et al., 1998; kroon et al., 1998; de kaenel et al., 1999; raffi, 2002; maiorano & marino, 2004; m a i o r a n o et al., 2004; c a p r a r o et al., 2005). l’integrazione di questi metodi stratigrafici permette una precisa calibrazione temporale di queste successioni e una loro affidabile correlazione a scala globale. le due sezioni che presentano una ideale continuità stratigrafica tra la base ed il tetto del calabriano sono la sezione di vrica e la sezione di montalbano ionico. nelle due successioni sono stati riconosciuti numerosi eventi biostratigrafici e diversi livelli tefra e sapropel che, unitamente ad un’accurata stratigrafia isotopica, oltre che magnetica nella sezione di vrica, consentono di apprezzarne l’estensione e la continuità stratigrafica (fig. 2). la sezione di ficarazzi, che colma il piccolo gap rilevato tra le sezioni di vrica e di montalbano ionico, e la sezione di valle di manche in cui è stato riconosciuto il limite matuyama/brunhes, integrano il record sedimentario in terra dell’intero intervallo calabriano (fig. 2). fig.1 ubicazione delle principali sezioni mediterranee del calabriano. location of the main calabrian mediterranean sections. 25il piano calabriano f ig . 2 s e z io n i s tr a ti g ra fi c h e d e ll ’i n te ro i n te rv a ll o c a la b ri a n o c o rr e la te c o n i l re c o rd i s o to p ic o i n o c e a n o a tl a n ti c o ( b ic k e r t e t a l. , 1 9 9 7 ) e o c e a n o p a c if ic o ( s h a c k l e t o n e t a l. , 1 9 9 5 ; m ix e t a l. , 1 9 9 5 a , b ) e c o n q u e ll o i l re c o rd a s tr o n o m ic o d i l a s k a r e t a l. (2 0 0 4 ). è i n o lt re r ip o rt a ta l a s tr a ti g ra fi a a s a p ro p e l e d i c ic li d i in s o la z io n e d a l o u r e n s e t a l. (2 0 0 4 ) e d a l o u r e n s (2 0 0 4 ). s o n o i n fi n e in d ic a te l a s tr a ti g ra fi a i s o to p ic a d i v ri c a d a l o u r e n s e t a l. ( 1 9 9 6 a ); q u e ll a d i f ic a ra z z i d a v e r g n a u d -g r a z z in i e t a l. ( 1 9 9 4 ), q u e ll a d i v a ll e d i m a n c h e d a c a p r a r o e t a l. ( 2 0 0 5 ) e d i n fi n e q u e ll a d i m o n ta lb a n o i o n ic o d a c ia r a n f i e t a l. (2 0 0 1 ). l a l it o s tr a ti g ra fi a e g li e v e n ti b io s tr a ti g ra fi c i d i v ri c a s o n o d i l o u r e n s e t a l. ( 1 9 9 6 a ) e d i l o u r e n s e t a l. ( 1 9 9 8 ); q u e ll i d i f ic a ra z z i s o n o r ip re s i d a d i s t e f a n o & r io (1 9 8 1 ) e d a s p r o v ie r i (1 9 9 3 ); q u e ll i d i v a ll e d i m a n c h e d a m a s s a r i e t a l. (2 0 0 2 ), c a p r a r o e t a l. ( 2 0 0 5 ); i n fi n e q u e ll i d i m o n ta lb a n o i o n ic o d e ri v a n o d a c ia r a n f i & d ’a l e s s a n d r o e t a l. (2 0 0 5 1 ) e d a m a io r a n o e t a l. ( 2 0 0 4 ). l e g e n d a f o : fi rs t o c c u rr e n c e , l o : la s t o c c u rr e n c e , f c o : fi rs t c o m m o n o c c u rr e n c e , l c o : la s t c o m m o n o c c u rr e n c e , r e : ri e n tr o ; td : te m p o ra n e a a s s e n z a . t h e s tr a ti g ra p h ic s e c ti o n s o f th e c a la b ri a n s ta g e a re c o rr e la te d w it h t h e i s o to p ic r e c o rd o f a tl a n ti c o c e a n ( b ic k e r t e t a l. , 1 9 9 7 ) a n d o f p a c if ic o c e a n ( s h a c k l e t o n e t a l. , 1 9 9 5 ; m ix e t a l. , 1 9 9 5 a , b ) a n d w it h t h e a s tr o n o m ic r e c o rd ( l a s k a r e t a l. , 2 0 0 4 ). t h e s a p ro p e l s tr a ti g ra p h y a n d i n s o la ti o n c y c le s ( l o u r e n s e t a l. , 1 9 9 6 b ; l o u r e n s e t a l. 2 0 0 4 ) a re a ls o r e p o rt e d . in a d d it io n t h e is o to p ic s tr a ti g ra p h y o f v ri c a s e c ti o n ( l o u r e n s e t a l. ,1 9 9 6 b ), f ic a ra z z i s e c ti o n ( v e r g n a u d -g r a z z in i, e t a l. , 1 9 9 4 ), v a ll e d i m a n c h e s e c ti o n ( c a p r a r o e t a l. , 2 0 0 5 ) a n d m o n ta lb a n o i o n ic o s e c ti o n ( c ia r a n f i e t a l. , 2 0 0 1 ) a re s h o w n . l it h o s tr a ti g ra p h y a n d b io s tr a ti g ra p h ic e v e n ts a re f ro m l o u r e n s e t a l. (1 9 9 6 a ) a n d f ro m l o u r e n s e t a l. (1 9 9 8 ) in v ri c a s e c ti o n , fr o m d i s t e f a n o & r io (1 9 8 1 ) a n d s p r o v ie r i (1 9 9 3 ) in f ic a ra z z i s e c ti o n , fr o m m a s s a r i e t a l. ( 2 0 0 2 ) a n d f ro m c a p r a r o e t a l. (2 0 0 5 ) in v a ll e d i m a n c h e s e c ti o n a n d fr o m c ia r a n f i & d ’a l e s s a n d r o (2 0 0 5 ) a n d f ro m m a io r a n o e t a l. (2 0 0 4 ) in m o n ta lb a n o i o n ic o s e c ti o n . l e g e n d a f o : fi rs t o c c u rr e n c e , l o : la s t o c c u rr e n c e , f c o : fi rs t c o m m o n o c c u rr e n c e , l c o : la s t c o m m o n o c c u rr e n c e , r e : re e n tr y ; td : te m p o ra ry d is a p p e a ra n c e . referenze bibliografiche a g u i r r e e. & p a s i n i g. (1985) the pliocene pleistocene boundary. episodes, 8, 116-120. bassett m. g. (1985) towards a "common language" in stratigraphy. episodes, 8, 87-92. berggren w.a. & van couvering j.a. 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(1994) a refined pliocene to early pleistocene chronostratigraphic frame at odp hole 653a (west mediterranean). marine geology, 117, p. 329-349. 28 ms. ricevuto il 2 aprile 2008 testo definitivo ricevuto il 17 aprile 2008 ms. received: april 2, 2008 final text received: april 17, 2008 ciaranfi et al. imp.tertulliani& studio macrosismico del terremoto del gran sasso (italia centrale) del 5 settembre 1950: implicazioni sismotettoniche andrea tertulliani 1, fabrizio galadini 1, fabio mastino 2, antonio rossi 1 & maurizio vecchi 1 1 istituto nazionale di geofisica e vulcanologia, via di vigna murata 605, 00143 roma 2 collaboratore esterno riassunto: a. tertulliani, f. galadini, f. mastino, a. rossi & m. vecchi, studio macrosismico del terremoto del gran sasso (italia centrale) del 5 settembre 1950: implicazioni sismotettoniche. (it issn 0394-3356, 2007). il 5 settembre 1950 alle 4.08 (gmt), un forte terremoto fu avvertito in tutta l’italia centrale e arrecò gravi danni in diversi centri abitati delle province di teramo, pescara, l’aquila e rieti. questo evento è il massimo terremoto storico avvenuto nell’area del gran sasso d’italia, zona che secondo i cataloghi sismici italiani, è caratterizzata da un’attività sismica relativamente modesta. questo lavoro è uno studio di revisione del terremoto del 1950 e del periodo sismico che ne seguì tra il 1950 e il 1951. scopo della ricerca è quello di ampliare il quadro delle conoscenze su questo sisma e di inquadrarlo nel contesto sismotettonico regionale. la ricerca ha condotto al reperimento di molti documenti originali, sinora inediti, sia relativi alla scossa del 5 settembre 1950, che a quella dell’8 agosto 1951, che rappresenta l’evento più forte del periodo sismico successivo alla scossa principale. i risultati consistono in una maggiore completezza delle informazioni sul terremoto, anche relativamente al ruolo delle repliche nel quadro del danneggiamento. il numero dei punti di intensità risulta triplicato rispetto a quanto finora conosciuto. gli elementi di analisi contribuiscono al calcolo di nuovi parametri ipocentrali e a fornire una ipotesi interpretativa riguardo alla sorgente responsabile del terremoto. in base ai dati acquisiti sulla distribuzione del danno è possibile ipotizzare che il terremoto del 1950 sia stato causato da una sorgente con direzione circa eo, situata al di sotto dell’edificio strutturale della laga, tra campotosto e pietracamela. abstract: a. tertulliani, f. galadini, f. mastino, a. rossi & m. vecchi, on september 5, 1950 (04:08 gmt), a strong earthquake struck a large part of central italy, causing heavy damage in the districts of teramo, pescara, l’aquila and rieti. (it issn 0394-3356, 2007). this earthquake is considered, in the italian seismic catalogues, as the largest event which occurred in the gran sasso range area. this area is characterized by an infrequent and moderate seismicity. on the contrary several neighboring areas are prone to a high and frequent seismicity. this paper aims to reappraise the 5 september 1950 earthquake and the following seismic period, deepening our knowledge of this event from the macroseismic and seismotectonic points of view. historical research in public archives allowed us to retrieve many unpublished documents, related to the 1950 earthquake and to the strongest aftershock which occurred in 8 august 1951. very important documents are in particular the “genio civile” folders about damage reconnaissance in the provinces of teramo and rieti. results concern the large increase of intensity points, from 137 to 386 for the 1950 event, and from 33 to 94 for the 1951 event, with respect to the known literature. maximum intensities are i=viii for 1950 earthquake and i= vii for 1951. by means of the boxer code version 3.3 (gasperini et al., 1999) new epicentral parameters have been calculated from macroseismic data, together with the macroseismic magnitude values (maw=5.9±0.2, for the 1950 event and maw=5.2±0.2 for the 1951 aftershock). finally, a hypothesis about the seismogenic source responsible for the mainshock is proposed. according to the damage distribution, an ew oriented source (strike 91,5±18, length 10,7 km, width 7,4 km) can be hypothesized, located below the laga mountains, not related to known tectonic structures of the region. the seismogenic source of the 1950 earthquake could therefore be represented by a blind fault pertaining to a structural level deeper than that of the active normal faults which affects the apennine extensional domain. parole chiave: gran sasso d'italia, terremoto 1950, macrosismica, sismotettonica. keywords: gran sasso d'italia, 1950 earthquake, macroseismics, seismotectonics. il quaternario italian journal of quaternary sciences 19(2), 2006 195 214 1. introduzione la conoscenza delle caratteristiche sismotettoniche della regione abruzzese e, più in generale, dei settori appenninico ed adriatico dell'italia centrale non è omogeneamente distribuita. l'emergenza in superficie delle faglie attive responsabili di terremoti con magnitudo anche superiore a 6.5 e i dati disponibili sugli effetti di un buon numero di terremoti distruttivi hanno consentito, fin dalla fine degli anni '90, di formulare ipotesi sulle caratteristiche sismogenetiche dei settori intermontani (es. barchi et al., 2000). per contro, l'occorrenza di terremoti con magnitudo minore rispetto a quelli avvenuti all'interno della catena, la lacunosità dell'informazione sulla distribuzione del danno di alcuni tra questi terremoti e un quadro di tettonica attiva assai meno chiaro hanno reso più problematica l'elaborazione di sintesi sismotettoniche per il settore adriatico. soltanto in tempi recenti, infatti, è iniziata la pubblicazione di lavori finalizzati alla definizione delle caratteristiche sismogenetiche delle aree cosiddette "esterne" (si veda, per le marche, vannoli et al., 2004). come osservato, uno degli aspetti che ostacola la caratterizzazione sismogenetica del settore adriatico è la non completa conoscenza della distribuzione del danno nei diversi terremoti. ciò vale certamente per alcuni eventi sismici abruzzesi, tra cui vanno annoverati i terremoti che hanno interessato l'area teramana (ma anche le province di l'aquila e rieti) nel 1950 e 1951. in questa ottica, il presente lavoro intende fornire un nuovo quadro conoscitivo sulla distribuzione del danno relativa ai due eventi principali di questo periodo sismi196 a. tertulliani et al. co (5 settembre 1950, riportato con maw=5.7 e io viii=mcs e 8 agosto 1951, riportato con maw=5.3 e io vii mcs, in gruppo di lavoro cpti, 2004, di qui in avanti cpti04). pertanto, dopo un ampio capitolo di inquadramento sulle caratteristiche della tettonica attiva e sulle conoscenze sismotettoniche dei settori appenninico ed adriatico dell'italia centrale, verranno approfonditi gli aspetti della ricerca sulla distribuzione del danno dei terremoti del 1950 e 1951 e discusso il nuovo quadro conoscitivo. infine, saranno fatte alcune ipotesi sulla sorgente sismogenetica responsabile dell'evento del 1950. 2. inquadramento sismotettonico della regione colpita dal terremoto del 1950 le caratteristiche geologico-strutturali della regione abruzzese e dell'area interessata dai terremoti del 1950 e 1951 sono legate all'evoluzione tettonica dell'arco appenninico settentrionale, intendendo con ciò la porzione di catena compresa tra il molise ed il settore ligure-piemontese (es. patacca et al., 1990). in sostanza, la strutturazione sarebbe il risultato della migrazione delle unità meso-cenozoiche verso ne, mediante l'attivazione di thrust progressivamente più recenti che, nel caso abruzzese, portano le formazioni di piattaforma carbonatica o di bacino ad accavallarsi generalmente su quelle di riempimento delle avanfosse. questo motivo cinematico rappresenterebbe la risposta crostale all'arretramento flessurale della placca adriatica in subduzione verso ovest (malinverno & ryan, 1986; patacca et al., 1990; doglioni, 1995). nel corso del quaternario, il fronte compressivo più esterno si sarebbe collocato nei settori costieri o nell'offshore adriatico lungo la penisola (es., cnr-pfg, 1983; patacca et al., 1990; argnani et al., 1991; calamita et al., 1991; bigi et al., 1995a; argnani, 1998; bolis et al., 2003; scrocca, 2006). tuttavia, l'attività recente delle strutture compressive esterne è argomento di discussione. secondo alcuni autori l'attività quaternaria dei thrust esterni potrebbe essere conclusa nel corso del quaternario inferiore (es. di bucci & mazzoli, 2002 e relativa bibliografia). in area abruzzese, viene considerata inattiva dal pleistocene inferiore la struttura definita come thrust costiero, da silvi marina verso sud (bigi et al., 1995a; calamita et al., 2002). di questo fronte compressivo, il bacino di pescara rappresenterebbe l'avanfossa, con deposizione silicoclastica plio-pleistocenica (calamita et al., 2002). tuttavia, la sismica a riflessione disponibile, per motivi legati alla tecnica di acquisizione, non permette di caratterizzare l'attività tettonica pleistocenica. nelle sezioni geologiche, il piegamento della base del pleistocene inferiore, nei punti in cui il pleistocene è sovrapposto alle faglie inverse plioceniche, sarebbe legato all'interpolazione dei differenti spessori di depositi quaternari (nel tetto e nel letto dei sovrascorrimenti) derivabili dai dati di pozzo (es. calamita et al., 2002 e 2003; bolis et al., 2003; scisciani, com. pers., 2006). inattivi sono considerati anche i thrust legati alle strutture della maiella e casoli-bomba (calamita et al., 2002). per contro, l'attività quaternaria (anche tardoquaternaria) nei settori padani dell'arco appenninico settentrionale sembrerebbe più evidente (es. burrato et al., 2003). nell'area adriatica marchigiana, thrust e pieghe quaternarie sarebbero presenti nell'offshore fino a poche decine di chilometri dalla costa o a ridosso di essa (es. argnani, 1998; vannoli et al., 2004). queste evidenze geologiche per il settore padano e marchigiano-adriatico, nonché la sismicità legata a sorgenti compressive nelle aree padana e marchigiana (es. burrato et al., 2003; vannoli et al., 2004), le informazioni sullo stress in atto (montone & mariucci, 1999; mariucci et al., 1999; mariucci & müller, 2003) e l'evidenza di una litosfera in subduzione (es. amato et al., 1998b; di stefano et al., 1999; lucente et al., 1999) sembrano supportare l'ipotesi di attività recente dei fronti compressivi dell'intero arco appenninico settentrionale (o della maggior parte di esso). mentre alla fine del pliocene il fronte compressivo andava ad attestarsi in area adriatica, nelle porzioni più interne iniziava il sollevamento che ha portato alla formazione dell'attuale catena appenninica (d'agostino et al., 2001; galadini et al., 2003). contemporaneamente al sollevamento, i settori assiali dell'appennino hanno subito fagliazione legata al regime tettonico estensionale (galadini et al., 2003; centamore & nisio, 2003). l'attività delle faglie dirette ha portato alla formazione di bacini intermontani con centinaia di metri di spessore di sedimenti plio-quaternari (bosi et al., 2003). la persistenza dell'attività di alcune di tali faglie (es. faglie del fucino, ovindoli-pezza, campo imperatore, norcia, ecc., fig. 1) è testimoniata dalla dislocazione di forme e depositi del pleistocene superiore-olocene. le faglie considerate attive sono organizzate in due o tre sistemi (in funzione delle differenti visioni degli autori es. galadini & galli, 2000 e boncio et al., 2004; fig. 1) con andamento parallelo all'asse della catena e per alcune di esse si hanno evidenze sismologico-storiche e paleosismologiche di attivazione durante terremoti degli ultimi secoli (galadini & galli, 2000 e relativa bibliografia). altre faglie normali ad est della zona interessata da attività nel pleistocene superiore-olocene caratterizzate da elevati rigetti verticali (ad es. i margini occidentali della maiella e della montagna dei fiori), sono probabilmente la testimonianza di ingenti dislocazioni pree/o sin-orogeniche (scisciani et al., 2000; scisciani et al., 2001; fubelli & galadini, 2005). l'attività recente di tali faglie, ipotizzata da alcuni autori (si vedano vezzani et al., 1998 e ghisetti & vezzani, 2002, per la maiella), è probabilmente da escludersi. per quanto riguarda l'area teramana, cioè l'area interessata dal terremoto del 1950, rilevamenti finalizzati alla ricostruzione dell'evoluzione geologica tardo-quaternaria del versante orientale della montagna dei fiori hanno evidenziato l'assenza di tracce di attività recente lungo la faglia normale, a fronte di un rigetto verticale pre-quaternario di svariate centinaia di metri (fubelli & galadini, 2005). depositi di versante probabilmente attribuibili al pleistocene medio sigillano la faglia. tracce di dislocazioni recenti, evidenziate dalla presenza di scarpate di faglia in roccia, sono attribuibili a movimenti gravitativi profondi di versante. queste osservazioni sull'attività delle faglie normali più esterne nell'appennino centrale chiariscono che, probabilmente, la fagliazione normale attiva più orientale, legata a strutture di lunghezza superiore ai 15-20 km, è da riferirsi al sistema m.ti della laga-gran sasso-m. morrone (es. galadini & galli, 2000). le faglie normali più esterne sono da ritenersi inattive. il quadro strutturale dei settori esterni, per quanto 197studio macrosismico del terremoto del gran sasso ... fig. 1 schema sismotettonico dell'area colpita dal terremoto del 1950. l'andamento delle faglie normali è derivato da galadini e galli (2000), con modifiche. gli epicentri dei terremoti con maw≥5.5 sono riportati secondo quanto in gruppo di lavoro cpti (2004), tranne il terremoto del 1997 (14 ottobre, ml 5.5), la cui ubicazione epicentrale è derivata da amato et al. (1998a). il terremoto del 1943, di magnitudo maw inferiore a 5.5 (5.02), è stato inserito nello schema in quanto più volte citato nel testo. la traccia della "struttura costiera" è tratta da calamita et al. (2003). le strutture trasversali all'andamento della catena sono tratte dai lavori di adamoli, (1993) ("b" e "c", valle del tordino e valle del vomano), de alteris, (1995) ("a", definita nel lavoro come "squalo line"), vezzani et al., (1998) ("b" e "c"), bolis et al., (2003) ("a", definita nel lavoro come "roseto line"). faglie interne alla catena appenninica: 1) sistema di faglia di norcia; 2) faglia del monte vettore; 3) faglia dei monti della laga; 4) sistema di faglia dell'alta valle dell'aterno; 5) sistema di faglia assergi-campo imperatore; 6) faglia della valle del salto; 7) sistema di faglia ovindoli-pezza-campo felice-colle cerasitto; 8) sistema di faglia della media valle dell'aterno; 9) faglia del monte morrone; 10) sistema di faglia del fucino; 11) faglia del monte porrara; 12) faglia della valle del liri; 13) faglia aremogna-cinquemiglia; 14) faglia dell'alta valle del sangro. seismotectonic sketch of the 1950 earthquake area. normal faults are redrawn from galadini and galli (2000). epicentres of maw ≥5.5 earthquakes have been derived from working group cpti (2004), excluding 1997 earthquake (october 14, ml=5.5), that is from amato et al. (1998a). 1943 earthquake, maw=5.0, is anyway indicated because it has been cited in the article. the trace of the so called “coastal sstructure” line is byhas been derived from calamita et al. (2003). the faults transverseal structures trendingto the main trend of the apennine chain are have been derived from adamoli, (1993) ("b" e "c", tordino valley and vomano valley), de alteriss, (1995) ("a", defined by the authors as "squalo line"), vezzani et al. (1998) ("b" e "c"), bolis et al., (2003) ("a", defined by the authors as "roseto line"). appenninicfaults of the inner apennine chain internal faults: 1) norcia fault system; 2) mount vettore fault; 3) laga mountainss fault; 4) upper aterno valley fault system; 5) assergi-campo imperatore fault system; 6) salto valley fault; 7) ovindolipezza-campo felice-colle cerasitto fault system; 8) aterno valley fault system; 9) mount morrone fault; 10) fucino fault system; 11) mount porrara fault; 12) liri valley fault; 13) aremogna-cinquemiglia fault; 14) upper sangro valley fault. 198 attiene al regime tettonico in atto, potrebbe essere complicato dalla presenza di faglie ad andamento trasversale alla catena. elementi strutturali con questa geometria sarebbero evidenziati dai dati offshore. in particolare, ci si riferisce ad una faglia ("squalo lineament" in de alteris 1995; "roseto line" in bolis et al., 2003) a cinematica incerta (forse trascorrente destra) in corrispondenza del proseguimento a mare della valle del vomano. in prossimità di tale struttura, i thrust marchigiani in offshore sembrano subire una brusca interruzione e non proseguire verso sud. la presenza di elementi strutturali trasversali alle principali direttrici della catena non sarebbe esclusiva di questo settore (si vedano per esempio la c.d. linea delle tremiti, e le sorgenti sismogenetiche responsabili della sequenza sismica di san giuliano di puglia del 2002; valensise et al., 2004; di luccio et al., 2005; di bucci et al., 2006; scrocca, 2006). da quanto finora evidenziato, emerge una sostanziale differenza delle conoscenze sul quadro strutturale relativo al regime tettonico in atto dell'area in esame. decisamente meglio conosciuto è il contesto strutturale del settore di catena appenninica. le aree esterne sono, invece, meno caratterizzate, sia per quanto attiene alla attività delle strutture compressive ad andamento appenninico (di cui non si può affermare con certezza od escludere l'attività recente), sia per quanto attiene la presenza ed il ruolo delle faglie ad andamento trasversale alla catena. questo quadro conoscitivo si riflette, ovviamente, sulle ipotesi sismotettoniche, in particolare per quanto riguarda la definizione delle sorgenti sismogenetiche dei terremoti principali. in pratica, terremoti al di sopra della soglia del danno interessano sia il settore interno (in particolar modo) che quello esterno della regione abruzzese (es. cpti04). i grandi terremoti storici che hanno interessato la catena, ben caratterizzati per quanto riguarda la distribuzione delle intensità, sono attribuibili a faglie normali con direzione appenninica. ciò vale per i terremoti del 14 gennaio 1703 (galli et al., 2005), 2 febbraio 1703 (es., moro et al., 2002) e 13 gennaio 1915 (galadini & galli, 1999 e relativa bibliografia). il confronto tra schema delle faglie attive e distribuzione della sismicità evidenzia che i terremoti di magnitudo moderata si collocano al tip dei segmenti principali (es. 1461, 1639, 1762, 1904, 1958, 1984) o in corrispondenza dei segmenti minori di più lunghi sistemi di faglia (es. 1328, 1599, 1730, 1799, 1859, 1979, 1997). quest'ultima relazione riguarda soprattutto l'area umbro-marchigiana (es. galadini et al., 1999), mentre la prima è più tipica dell'area abruzzese. sembrerebbero anche definite, grazie ad informazioni paleosismologiche ed archeosismologiche, le sorgenti di due terremoti distruttivi dell'antichità, vale a dire l'evento del ii secolo d.c. (riportato convenzionalmente come 101 d.c. in cpti04) e quello del 508 d.c. il primo è tentativamente attribuito alla sorgente del m. morrone (galadini & galli, 2001), il secondo alla sorgente del fucino, cui è pure riferito il terremoto del 1915 (galadini & galli, 1999). nell'ambito del settore interno della catena, sono invece non definite le sorgenti causative della sequenza del 1349, per i più scarsi dati sulla distribuzione del danno. completamente diverso è il quadro delle conoscenze sismogenetiche per le zone esterne, in particolare per quelle abruzzesi. il terremoto del 1706 (maw=6.6, in cpti04) ha interessato l'intera regione circostante la montagna della maiella, con gravi danni nella piana di sulmona e nella valle dell'aventino. ma danni significativi sono attribuiti a tutti gli abitati della fascia pedemontana della maiella. l'evento del 1881 (maw=5.6) ha interessato il settore compreso tra la maiella e la costa adriatica con danni notevoli a orsogna, lanciano, guardiagrele, castel frentano. il terremoto del 1933 (maw=5.7) ha un'area di danneggiamento paragonabile a quella del 1706, ma con livello del danno sensibilmente minore. i terremoti del 1950 (maw=5.7) e del 1951 (maw=5.3), oggetto della presente nota, hanno interessato soprattutto un'ampia area dell'abruzzo teramano ed abitati delle province di l'aquila e rieti. per nessuno di questi eventi sono disponibili ipotesi attendibili sulla sorgente causativa. tuttavia, alcune considerazioni possono essere fatte per i terremoti del 1706 e del 1950 in base alla bibliografia disponibile. per il primo dei due, l'utilizzo dell'algoritmo boxer (che definisce la geometria della faglia causativa a partire da una certa distribuzione del danno; gasperini et al., 1999) ha generato una sorgente con direzione no (gasperini et al., 1999) che però non ha avuto, finora, riscontro geologico. secondo meletti et al. (1988) il terremoto del 1706 potrebbe essere attribuito all'attivazione di una parte della c.d. linea ortona-roccamonfina, elemento strutturale con direzione da ne-so a ns che separerebbe l'arco appenninico settentrionale da quello meridionale. tuttavia, evidenze di attività recente lungo questa fascia di deformazione non sono state ancora osservate. per quanto riguarda il 1950, pur mancando ipotesi sismogenetiche conclusive, sembra utile menzionare il meccanismo focale pubblicato da gasparini et al. (1985). questo suggerisce la possibile attivazione di una struttura con direzione trasversale alla catena (neso). va comunque ricordato che i dati sismometrici a disposizione sono qualitativamente e quantitativamente tali da rendere necessario considerare con cautela tale meccanismo focale. a differenza del settore adriatico abruzzese, per quello marchigiano (a nord dell'area rappresentata in figura 1) è disponibile un'interpretazione sismogenetica che lega i terremoti di magnitudo moderata con l'attivazione di sorgenti con meccanismo tipo thrust (vannoli et al., 2004). nel lavoro citato, in sostanza, si ammette il ruolo sismogenetico delle strutture compressive costiere marchigiane. 3. il terremoto del 5 settembre 1950 e l’attività sismica nell’area del gran sasso nel periodo 1950-1951 il biennio 1950-1951 vede l’area del gran sasso – monti della laga sede di un’attività sismica abbastanza intensa, culmine della quale è il terremoto del 5 settembre 1950 (04.08 gmt). secondo i cataloghi sismici nazionali questo evento è il più significativo di quelli con origine nell’area, che nel complesso è sede di una moderata attività sismica. secondo il catalogo parametrico dei terremoti italiani (cpti04) l’epicentro a. tertulliani et al. 199 ricade alle pendici nord del gran sasso. in precedenza, la zona settentrionale della provincia di teramo era stata colpita dal terremoto marchigiano del 3 ottobre 1943 (epicentro a nord di ascoli piceno, fig. 1), i cui effetti si sommeranno probabilmente ai danni del 1950. la scossa principale fu preceduta di pochi minuti da una forte scossa premonitrice avvertita in molte località (di filippo & marcelli, 1951; ing, 1950). il quadro degli effetti vide due vittime e un centinaio di feriti, oltre ad una estesa area di danneggiamento tra le province di rieti, teramo, pescara e ascoli piceno. alla scossa del 5 settembre 1950 seguirono diverse repliche: tra queste le più significative furono quelle del 18 settembre 1950 con lievi danni nell’area di montereale (monachesi & castelli, 1992), quella dell’8 marzo 1951 con danni nell’area di pizzoli e campotosto (postpischl, 1985) e quella del 21 maggio 1951, sconosciuta alla letteratura sismologica, con lievi danni nell’area di campli. l’8 agosto 1951 (19.56 gmt) un altro forte terremoto colpì le stesse aree provocando nuovi e diffusi danneggiamenti in diverse località. 2.1 stato delle conoscenze l’unico studio specifico pubblicato sul terremoto del 1950 è quello di di filippo e marcelli (1951), che costituisce pertanto il cardine delle conoscenze per tutte le successive revisioni (monachesi & castelli, 1992; monachesi & stucchi, 1997). il database dom4.1 (monachesi & stucchi, 1997), che contiene un piano quotato di 137 località, apporta solo qualche modifica rispetto a quello dello studio succitato. secondo il cpti04, il terremoto del 5 settembre 1950 (04.08 gmt) è caratterizzato da un’intensità epicentrale (io) di viii grado mcs e da un valore di magnitudo (maw) pari a 5.7. nel lavoro di di filippo e marcelli (1951) sono riportati, oltre al campo macrosismico, un elenco di 137 località di segnalazione con la rispettiva intensità assegnata, ma solo per 13 di queste località sono descritti, in modo spesso sommario, gli effetti del terremoto. probabilmente gli autori si avvalsero, senza una specifica citazione, delle cartoline sismiche. queste ultime erano schede prestampate che in caso di terremoto venivano compilate da corrispondenti locali ed inviate all’ufficio centrale di meteorologia ed ecologia agraria che era preposto dallo stato a raccogliere le informazioni inerenti i risentimenti sismici sul territorio. sulle cartoline sismiche il corrispondente descriveva sommariamente gli effetti del terremoto nella località di pertinenza. questo sistema di raccolta di dati macrosismici è stato per circa 70 anni un’importante fonte di informazione sui sismi che avvenivano in territorio italiano. di filippo e marcelli calcolarono la localizzazione ipocentrale, (h < 10 km) (vedi tabella 1) su base strumentale. per dare un’idea delle varie interpretazioni riguardo alla localizzazione del terremoto del 1950, elenchiamo in tabella 1 quelle riportate in letteratura. il terremoto dell’8 agosto 1951 alle ore 21.56 (ora locale) viene parametrizzato in cpti04 con magnitudo maw=5.3 ed intensità epicentrale di vii mcs. i danni più gravi furono riscontrati nella provincia di teramo. secondo il cpti04 l’epicentro ricadrebbe al confine tra marche ed abruzzo. consultando i cataloghi sismici nazionali si evidenzia come la bibliografia relativa a questo evento sia piuttosto limitata. il record del cpti04 ha come fonte di riferimento il database macrosismico dom4.1 (monachesi e stucchi, 1997), che si limita a valutare l’intensità sulla base di repertori sismologici tradizionali. nella tabella 2 è mostrata l’evoluzione della stima tab. 1 parametri del terremoto del 5 settembre 1950, ore 04.08, come riportati nei principali cataloghi e nelle altre fonti. le localizzazioni ing, iss e di filippo e marcelli sono strumentali, mentre le altre sono epicentri macrosismici. caloi et al. riprendono di filippo e marcelli. epicentral parametres of the september 5, 1950 earthquake, 04:08 gmt, reported in the main seismic catalogues and other sources. ing, iss and di filippo and marcelli are instrumental locations, the others are macroseismic epicentres. caloi et al. followed di filippo and marcelli. coordinate fonte area epicentrale latit. longit. i0 mcs magnitudo ing (1950) 42,508 13,350 m=5.1 iss (1950) gran sasso 42,600 13,500 viii di filippo e marcelli (1951) campotosto 42,513 13,327 viii m=5.4 caloi et al. (1969) gran sasso 42,516 13,327 ix m=7.1 gasparini et al. (1985) 42,600 13,500 m=5.5 pospischl (1985) campotosto 42,516 13,350 viii ml=5.4 camassi e stucchi (1997) gran sasso 42,500 13,600 viii ms=5.6 cpti04 gran sasso 42,516 13,657 viii maw=5.7 tab. 2 parametri epicentrali del terremoto dell’8 agosto 1951, ore 19:56, come riportati nei principali cataloghi e nelle altre fonti conosciute. epicentral parametres of the august 8, 1951 earthquake, 19:56 gmt, reported in the main seismic catalogues and other sources. coordinate fonte area epicentrale latit. longit. i0 mcs magnitudo ing (1951) 42,600 13,500 m=5.1 iss (1951) gran sasso 42,600 13,500 gasparini et al. (1985) 42,600 13,500 vii-viii m=4.9 pospischl (1985) cortino 42,600 13,500 viii ml=4.9 camassi e stucchi (1997) monti della laga 42,750 13,500 viii ms=5.0 cpti04 monti della laga 42,704 13,546 vii-viii maw=5.3 studio macrosismico del terremoto del gran sasso ... 200 dei parametri epicentrali di questo terremoto attraverso i cataloghi sismici e gli autori che ne fanno menzione: pfg (postpischl, 1985), nt4.1 (camassi & stucchi, 1997) e cpti (cpti04). il database dom4.1 fornisce un piano quotato con 33 località (fig. 6). la massima intensità fu assegnata alla sola località di canzano (prov. te), stimata del vii-viii grado, mentre alle altre località furono assegnate intensità comprese tra il ii ed il vi grado. 2.2 ricerca di dati al fine di migliorare e riordinare il quadro delle conoscenze sul terremoto del 5 settembre 1950, nonché fornire elementi utili alla comprensione sismotettonica dell’evento, è stata avviata una ricerca sistematica su fonti bibliografiche e documentarie relativa a tutti gli eventi sismici avvenuti nell’area durante il biennio 19501951. di seguito, viene fornito un quadro delle fonti utilizzate. giornali sono stati consultati i quotidiani nazionali più importanti ed uno locale (vedi elenco in bibliografia). l’indagine ha messo in evidenza come le notizie sul terremoto del 5 settembre 1950 siano presenti sui giornali fino a circa 2 settimane dopo l’evento, prima con le cronache degli inviati speciali, ricche di particolari, e poi con le corrispondenze locali. il terremoto del 8 agosto 1951 scompare molto più rapidamente dalle cronache. per una ventina di località i giornali sono risultati essere la sola fonte disponibile, fornendo quindi un contributo in termini di notizie inedite utili a completare il quadro degli effetti. documenti d’archivio gran parte della ricerca documentale è stata svolta presso gli archivi di stato delle province interessate dagli eventi, l’aquila (asa), rieti (asr), teramo (ast), pescara (asp). sono stati inoltre consultati l’archivio centrale dello stato di roma (acsr), l’archivio del genio civile di teramo (agct) e l'archivio storico dell’istituto nazionale di geofisica e vulcanologia (aingv). la documentazione di interesse è costituita principalmente dalla corrispondenza tra le autorità locali (sindaci, prefetto e sottoprefetto) e centrali (governo e ministeri). questo tipo di documentazione, contenuta nei fondi della prefettura (asa e ast), descrive in modo sintetico la situazione locale post-evento, limitandosi talvolta a far riferimento a documenti non più presenti nelle stesse buste. in alcuni casi, tuttavia, si tratta di resoconti abbastanza dettagliati, come le liste dei danneggiati con la descrizione del danno di cui si richiede il risarcimento; in altri casi sono stati rinvenuti documenti elencanti le somme elargite dai comitati di soccorso o direttamente dai comuni, come primo contributo per le situazioni più gravi. un altro fondo risultato utile è quello del genio civile (asp e asr), contenente le perizie di sopralluogo effettuate dai tecnici del genio civile presso molte località della provincia, e domande di risarcimento dei danni fatte dalla cittadinanza. particolarmente ricche di informazioni sono state alcune relazioni dei tecnici del genio civile della provincia di rieti, riguardanti i comuni di accumoli ed amatrice. una menzione particolare merita l’archivio del genio civile di teramo (agct), per la disponibilità e la quantità del materiale messo a disposizione. si tratta soprattutto delle pratiche istruite per le richieste di sussidi fatte dai proprietari degli immobili per riparazioni dei danni prodotti dal terremoto. la pratica era composta principalmente dalla domanda di sussidio, a cui erano allegati il preventivo dei lavori e la successiva verifica fatta dai tecnici del genio civile. da questi sussidi venivano escluse per legge le case rurali. data la mole documentale, l’indagine ha riguardato preferenzialmente le pratiche istruite dal genio civile, e approvate per il sussidio a conferma dell'avvenuto danno. per alcuni comuni dell'area teramana, le informazioni reperite in questo archivio sono risultate le uniche disponibili. in totale sono state consultate 46 buste relative ai danni avvenuti in 32 comuni, incluso teramo, con informazioni dettagliate anche per molte frazioni. il lavoro ha riguardato migliaia di incartamenti, e ha permesso di estrarre dall’enorme mole di documenti circa 2000 pratiche utili, relative a richieste di risarcimento. l'effettiva utilità dei documenti dell'archivio del genio civile di teramo ai fini di una assegnazione dell'intensità è comunque controversa per motivi legati all’iter burocratico. le pratiche avevano un percorso lungo e tortuoso che veniva spesso concluso dopo molto tempo (anche più di dieci anni). nel computo dei danni veniva sovente tenuto conto del cumulo con quelli dovuti a scosse successive, soprattutto con quelli causati dal terremoto dell’8 agosto 1951 (intensità vii mcs). inoltre era talvolta dichiarato l'intento di procedere alla riparazione anche dei danni di guerra. la mancanza poi, come accennato, della descrizione di danni alle proprietà rurali fa sì che il quadro generale degli effetti deducibile da questo tipo di documentazione sia purtroppo parziale. si tratta tuttavia degli unici documenti che descrivono in dettaglio il tipo di danneggiamento subito dagli immobili, fornendo anche indicazioni sul numero delle abitazioni interessate. e’ stata consultata la collezione delle cartoline sismiche dell’archivio storico dell’istituto nazionale di geofisica e vulcanologia (aingv), che raccoglie le corrispondenze da oltre 170 località, per il terremoto del 1950, e da 45 per il terremoto dell’8 agosto 1951. la consultazione delle cartoline sismiche è risultata basilare in quanto ha consentito di incrementare il numero delle località di risentimento conosciute e di migliorare in generale la qualità dei dati attraverso dettagliate descrizioni dei risentimenti. sono stati infine consultati alcuni manoscritti a carattere sismologico provenienti dalla collezione de panfilis (de panfilis, 1950-1959; de panfilis, sec. xx), che non hanno però fornito informazioni significative. per quanto riguarda il terremoto del 5 settembre 1950, la grande mole di informazioni raccolte e la rilettura critica delle fonti presenti nella letteratura nota hanno contribuito alla valutazione dell’intensità macrosismica, anche se purtroppo non è stato possibile reperire lo stesso tipo di fonte per tutte le località esaminate (vedi fig. 2a). e’ stata inoltre individuata una replica sconosciuta alla letteratura sismologica, avvenuta il 21 maggio 1951, che provocò lievi danni nell’area di campli. nella figura 2a è illustrato il contributo delle varie fonti rispetto al numero di località per le quali le stesse fonti sono disponibili. il documento d’archivio e la a. tertulliani et al. cartolina sismica rappresentano le tipologie di fonte più diffuse. hanno fornito dati rispettivamente per 182 e 175 località su 386 totali esaminate in questo studio. naturalmente la quantità delle fonti non è proporzionale alla loro efficacia nella descrizione degli effetti dovuti all'evento sismico, e quindi ai fini dell'assegnazione dei valori di intensità. inoltre per circa il 52% (201 su 386) delle località abbiamo a disposizione un solo tipo di citazione. per queste località non è stato possibile incrociare informazioni provenienti da diversi tipi di documenti. al termine dell’analisi delle fonti è stato comunque assegnato il valore di intensità a 336 località (vedi appendice a). per il terremoto dell’8 agosto 1951 tra le opere a carattere tecnico-scientifico consultate ve ne è una sola, che aggiunge ulteriori informazioni a quelle conosciute. il lavoro in questione è quello di marcelli e pannocchia (1962-1963) in cui si propone una mappa macrosismica realizzata con le notizie delle cartoline sismiche. nella figura 2b è evidenziato il contributo delle varie fonti rispetto al numero di località per le quali le stesse fonti sono disponibili. in generale, si può affermare che il terremoto del 1951 resta molto meno documentato dell’evento del 1950. 201 fig. 2a istogramma relativo alla distribuzione delle informazioni secondo il tipo di fonte relativa al terremoto del 1950. distribution of the information related to the 1950 earthquake, according to the kind different types of source. fig. 2b istogramma relativo alla distribuzione delle informazioni secondo il tipo di fonte relativa al terremoto del 1951. distribution of information related to the 1951 earthquake, according to the kind different types of source. per avere un quadro più completo della sismicità di riferimento, soprattutto in relazione al possibile cumulo dei danni nel periodo studiato, è stata approfondita la ricerca sull’evento del 12 marzo 1950 (18.15 gmt), segnalato dal bollettino sismico dell’ing (ing, 1950) con l’indicazione “accumoli vii mcs”, per chiarire se avesse potuto influenzare lo scenario del danneggiamento ricostruito. lo spoglio dei giornali ha dato esito negativo non essendovi riportata alcuna notizia su questa scossa. non è stato possibile effettuare una verifica sulle cartoline sismiche essendo mancante la parte della collezione riguardante il mese di marzo 1950. dalla documentazione consultata presso l’archivio di stato di rieti non sono emersi documenti riguardanti questa scossa. i giornali e la documentazione di archivio riportano sempre informazione sui terremoti di particolare rilievo del biennio 1950-1951. il silenzio delle fonti sulla scossa in oggetto fa ritenere pertanto che questa sia stata di intensità alquanto inferiore (≤ v mcs) rispetto a quanto segnalato sul bollettino ing (1950) e successivamente sui cataloghi pfg (postpischl, 1985) e cpti (cpti04). 2.3 assegnazione dell’intensità l’intensità macrosismica è stata stimata utilizzando la scala mercalli-cancani-sieberg (mcs) (mcs, 1930), ritenuta più adatta in riferimento al periodo storico in cui è avvenuto il terremoto ed al tipo di edilizia diffusa nell’area. le costruzioni colpite dal terremoto erano generalmente in pietra semplice, spesso non squadrata, costruite senza ausilio di cordoli. la maggioranza delle abitazioni era costituita al massimo da due piani in elevazione. e’ stata assegnata l’intensità a frazioni e località aventi un nucleo urbano rappresentativo, con l’esclusione di piccoli centri abitati formati da pochissime abitazioni e le case sparse, e sulla base di un corredo di informazioni significative sia qualitativamente (descrizione del risentimento) che quantitativamente (numero di elementi di diagnosi). le località maggiormente danneggiate dal terremoto del 5 settembre 1950 si trovano lungo una fascia a cavallo della catena del gran sasso e dei monti della laga, fra le province di rieti, l’aquila e teramo (fig. 3). a diverse località, sia frazioni che capoluoghi di comune, è stato assegnato l’viii grado mcs (vedi appendice a), in virtù di danni molto gravi alle strutture, muri portanti, tetti e solai, diversi collassi totali e di un diffuso danneggiamento generale alle abitazioni. molto estesa è risultata alla fine l’area di vii, a coprire quasi tutta la provincia di teramo e parte delle province di pescara, l’aquila, rieti e ascoli piceno. in tutta questa regione il danno è risultato largamente diffuso nel territorio, soprattutto sulle strutture portanti e le coperture. in molti casi è stata assegnata un’intensità incerta tra il vii e l’viii grado, a causa dell’incompletezza del quadro diagnostico. molti crolli o danni hanno interessato case isolate o edifici rurali, sparsi nelle campagne. in questi casi, il danno non è stato quantificato in termini di intensità. l’informazione è risultata comunque utile per completare e definire il quadro dell’area di maggior danno. la scarsità di informazioni non ha reso possibile una valutazione del risentimento e di conseguenza l'asstudio macrosismico del terremoto del gran sasso ... segnazione di un valore di intensità ad una serie di località. ad esse è stato assegnato il codice d per segnalare la generica presenza di danni. allo stesso modo la lettera f indica un generico risentimento dell’evento. e’ stato anche ricostruito il piano quotato del terremoto del 8 agosto 1951, avvenuto sempre nella stessa area (io= vii) (vedi appendice b). i danni si sono certamente cumulati a quelli dell’evento dell’anno precedente e pertanto la discriminazione degli effetti non sempre è stata possibile. nelle province di teramo, l’aquila e rieti le condizioni di stabilità degli edifici a circa un anno dal terremoto del 1950 erano ancora precarie. nella provincia di teramo la maggior parte delle domande per la ricostruzione furono accettate, infatti, ad oltre dieci anni dalla scossa. pertanto, gran parte dei lavori di recupero edilizio iniziarono quasi sicuramente dopo il terremoto dell’8 agosto 1951. alla luce di ciò appare manifesta la difficoltà di interpretare con univocità le informazioni relative ai danneggiamenti in termini di valutazione dell’intensità macrosismica. 3. risultati e discussione 3.1 la distribuzione del danno l’evento del 5 settembre 1950 interessò abitati che già avevano subito gli effetti dal forte terremoto di offida (prov. di ascoli piceno) del 3 ottobre 1943. questo ebbe una intensità all’epicentro pari all’ viii-ix mcs, e causò gravi danni anche nel teramano (monachesi & stucchi, 1997) con is pari al vii-viii a teramo ed altre località. inoltre, nell’immediato secondo dopoguerra, la maggior parte degli edifici, per mancanza di manutenzione, non erano in buone condizioni. al proposito, di filippo e marcelli (1951) asseriscono ”… le case sono malsicure ed assolutamente inadatte a resistere ad un terremoto”. dal punto di vista della ricerca macrosismica il quadro di riferimento si presenta quindi abbastanza complesso. tuttavia l’indagine archivistica ha dato risultati soddisfacenti permettendo il reperimento di numerosi nuovi dati che consentono di definire meglio la distribuzione dell’intensità sul territorio per entrambi i terremoti. se confrontiamo il piano quotato del terremoto del 5 settembre 1950, ottenuto nel presente lavoro con quello riportato in dom4.1, possiamo notare un notevole incremento del numero dei punti di intensità. si è passati, infatti, da 137 a 386 località (fig. 4). l’intensità massima risentita è l’viii mcs ed è la stessa di quella riportata da dom4.1 e da di filippo e marcelli (1951). le località con tale intensità sono passate da 10 a 14, mentre a 14 località è stata assegnata una intensità di vii-viii. il quadro del danneggiamento risulta essere stato 202 fig. 3 campo macrosismico del terremoto del 5 settembre 1950. con la d sono indicate in carta le località per le quali vi è segnalazione generica di danno non sufficiente per l’assegnazione dell’intensità. con f sono indicate quelle località per le quali vi è segnalazione generica di risentimento insufficiente per l’assegnazione dell’intensità. intensity map of the 5 september 1950. code d indicates generic damage; this information is not sufficient to assess an intensity value to the locality. code f indicates localities where the shock has been generally felt. a. tertulliani et al. più grave entro una fascia orientata circa eo posta tra il lago di campotosto in provincia di l’aquila e la valle del vomano (fig. 3); in questa area sono concentrate le intensità più elevate. intensità più basse sono state assegnate alle località ubicate verso la costa adriatica dove il terremoto fu avvertito con violenza, senza tuttavia registrare danni significativi (figg. 3 e 5). la magnitudo mw calcolata con il codice boxer 3.3 (gasperini et al., 1999) a partire dal piano quotato risulta pari a 5.9±0.2 lievemente più alta del 5.7 proposto in cpti04. a fronte dell’incremento del numero di località di viii grado, dovuto al grande dettaglio dell’indagine macrosismica, l’area di massima intensità risulta ridotta rispetto a quella delineata nella mappa di di filippo e marcelli (1951). l’apparente contraddizione tra il leggero aumento della magnitudo e la diminuzione dell’area di massimo danneggiamento, se rapportati con cpti04, è probabilmente spiegabile con il maggior numero di punti di massimo grado utilizzati, contestualmente alla loro concentrazione in un’area ridotta. analogamente al terremoto del 1950, anche per quello dell’8 agosto 1951, possiamo notare un notevole incremento del numero dei punti di intensità. si è passati, infatti, da 33 località documentate a 94 (fig. 6). l’intensità massima risentita, attribuita a 4 località, è stata del vii mcs, leggermente inferiore all’intensità massima riportata da dom4.1 (vii-viii mcs), alla sola 203 fig. 5 dettaglio della distribuzione delle intensità del terremoto del 5 settembre 1950 e ipotesi di sorgente sismogenetica (box blu) dall’applicazione dell’algoritmo boxer (gasperini et al., 1999). zoom of the intensity map of the 5 september 1950 with the indication of the seismogenic source (blue box) computed by means of the boxer code (gasperini et al., 1999). fig. 4 terremoto del 1950. confronto del numero di località ricadenti nelle classi di intensità tra i piani quotati di dom4.1 e del presente lavoro. non sono riportate le località per le quali: abbiamo solo segnalazione di danni (d = damage) ed intensità non assegnata e quelle per le quali abbiamo solo l’indicazione di un generico risentimento (f = felt) ed intensità non assegnata. le località per le quali abbiamo una segnalazione negativa sono riportate nel grafico con n. earthquake of 1950. comparison between number of localities, grouped into intensity classes, for dom4.1 and the present issue. the localities quoted as (d = damage) and (f = felt) are not taken into account for this graph. localities where the shock was not felt are reported in the graph with n. studio macrosismico del terremoto del gran sasso ... località di canzano. in appendice b è riportato il piano quotato relativo al terremoto; al termine dell’analisi delle fonti è stato assegnato un valore di intensità a 80 località sulle 94 riportate nel piano quotato. nella figura 7 è riportata la mappa della distribuzione dell’intensità ricavate dal piano quotato. il danneggiamento risulta essere stato più grave entro una fascia orientata circa eo posta tra montereale e isola del gran sasso passando per il massiccio del gran sasso ed interessando le province di l’aquila e teramo. verso la costa adriatica e le province di ascoli piceno e pescara il terremoto causò un forte risentimento senza provocare danni. la magnitudo mw calcolata risulta pari a 5.2 (gasperini et al., 1999). dall’analisi del piano quotato possiamo dire che questo terremoto ha interessato all’incirca la stessa area epicentrale di quello del 5 settembre 1950. questa analogia, insieme alla vicinanza temporale tra i due eventi, ci fa propendere a definire la scossa dell’8 agosto 1951 come una forte replica del terremoto del 5 settembre 1950, diversamente da quanto sinora considerato. 204 fig. 6 terremoto del 1951. confronto del numero di località ricadenti nelle classi di intensità tra i piani quotati di dom4.1 e del presente lavoro. non sono riportate le località per le quali: abbiamo solo segnalazione di danni (d = damage) ed intensità non assegnata e quelle per le quali abbiamo solo l’indicazione di un generico risentimento (f = felt) ed intensità non assegnata. 1951 earthquake. comparison between the number of localities, grouped into intensity classes, for dom4.1 and the present issue. the localities quoted as (d = damage) and (f = felt) are not taken into account for this graph. localities where the shock was not felt are reported in the graph with n. fig. 7 campo macrosismico del terremoto del 8 agosto 1951. con la d sono indicate in carta le località per le quali vi è segnalazione generica di danno non sufficiente per l’assegnazione dell’intensità. con f sono indicate quelle località per le quali vi è segnalazione generica di risentimento insufficiente per l’assegnazione dell’intensità. intensity map of the 8 august 1951. code d indicates generic damage; this information is not sufficient to assess an intensity value to the locality. code f indicates localities where the shock has been generically felt. a. tertulliani et al. 3.2 ipotesi sismogenetiche la ricostruzione del panorama degli effetti ci consente di riflettere sulla questione, sinora non risolta, della sorgente del terremoto del 1950. nel caso della scossa del 5 settembre 1950, il livello del danno è elevato su un'area decisamente ampia. l'asse maggiore della distribuzione dei punti di vii-viii/viii mcs (circa 55 km) è, in effetti, paragonabile a quello proprio di eventi caratterizzati da più elevata magnitudo in italia centrale (es. 14 gennaio 1703, maw=6.8, area di vii-viii mcs allungata, tra visso e cittaducale per circa 60 km). tale considerazione, a fronte della minore energia associata all'evento del 1950 porterebbe ad ipotizzare per esso un'origine più profonda di quella della maggior parte dei terremoti appenninici. inoltre, la distribuzione del danno mostra una sorta di orientamento preferenziale, circa eo, sia per il "campo vicino" che per quello "lontano". nel caso delle maggiori intensità, questo effetto di allungamento del campo macrosismico potrebbe essere dovuto ad una distribuzione degli abitati condizionata dalla morfologia eo del settore settentrionale della catena del gran sasso. tale ipotesi, tuttavia, non può essere avanzata nel caso dei punti di intensità minore, relativi ad abitati lontani dall'area del citato massiccio montuoso. e' pertanto ipotizzabile che la direzione preferenziale della distribuzione del danno sia da considerarsi come l'effetto della geometria della sorgente. l'utilizzo dell'algoritmo boxer vers 3.3 (gasperini et al., 1999) evidenzia che la distribuzione dei punti di intensità è compatibile con una sorgente con direzione ca. eo (azimuth 91,5±18), lunghezza 10,7 km, larghezza 7,4 km. l'andamento trasversale all'asse principale della catena appenninica sembrerebbe confermato dall'unico meccanismo focale disponibile (definito, però, su una ridotta informazione sismometrica) sebbene esso mostri direzioni ne-so dei piani focali (gasparini et al., 1985). in base a quanto sopra, è possibile ritenere che il terremoto del 1950 sia stato causato da una sorgente con direzione ca. eo, o comunque trasversale all'andamento della catena appenninica, ubicata a profondità superiore a quella a cui si originano i terremoti distruttivi dei settori intermontani (in genere fino a 10-15 km). e' da notare, in effetti, che la distribuzione del danno, e la relativa elaborazione con l'algoritmo boxer, suggeriscono una sorgente ubicata trasversalmente all'edificio strutturale dei monti della laga. tuttavia, la catena della laga è interessata da una faglia normale con direzione no-se, attiva nel pleistocene sup.-olocene, considerata come espressione superficiale di una delle sorgenti sismogenetiche appenniniche (galadini & galli, 2000). ciò farebbe pensare, e l'ampiezza dell'area danneggiata lo confermerebbe, che la sorgente eo del terremoto del 1950 si possa collocare ad un livello strutturale più profondo di quello a cui si colloca la sorgente con direzione no-se. come osservato nell'inquadramento sismotettonico, tracce di una faglia trasversale all'asse principale della catena appenninica sono osservabili nel quadro strutturale offshore (de alteris, 1995; bolis et al., 2003), ed una faglia viene dubitativamente ubicata in terra lungo la valle del vomano ed un'altra lungo la valle del tordino da più autori (adamoli, 1981 e 1993; vezzani et al., 1998). l'elemento strutturale che avrebbe originato l'evento del 1950 potrebbe essere una faglia profonda che interessa la litosfera adriatica in subduzione e che limita settori di tale placca caratterizzati da diversa velocità di sprofondamento/arretramento (si vedano ad esempio le varie ipotesi di bigi et al., 1995b; bolis et al., 2003). in tal senso, la sorgente sismogenetica rappresenterebbe un segmento di un sistema di faglia legato al processo di arretramento flessurale in atto. in alternativa, la sorgente potrebbe essere parte di un elemento strutturale passivo, ereditato da un quadro strutturale anche pre-orogenico (si vedano i condizionamenti pre-orogenici alla strutturazione in catena del margine appenninico esterno in calamita et al., 2002) o legato al processo flessurale non più in atto e riattivato nel presente regime tettonico. a tal proposito, si rammenta che questa è una delle ipotesi pubblicate per giustificare l'origine della sequenza di san giuliano di puglia del 2002 (valensise et al., 2004; di luccio et al., 2005), dovuta a sorgenti con direzione eo. per quanto concerne il terremoto del 1951, l'ubicazione dei suoi effetti nella zona danneggiata dall'evento precedente (fatto non desumibile dai piani quotati finora disponibili) fa pensare che esso rappresenti una forte replica del terremoto del 1950. anche per il 1951 si evidenzia, soprattutto per i gradi di intensità minori, un allungamento del piano quotato in direzione trasversale alla catena appenninica. tuttavia, il minor numero dei punti disponibili suggerisce cautela nell'ipotizzare una possibile geometria della sorgente causativa. 4. conclusioni la revisione macrosismica dei terremoti abruzzesi del 5 settembre 1950 e dell’8 agosto 1951 ha portato a modificare sostanzialmente il quadro conoscitivo di questi eventi. il livello di conoscenza è infatti migliorato sia in relazione al numero di punti di intensità, sia rispetto alla qualità dell’informazione in essi contenuta. in tabella 3 vengono elencati i parametri proposti nel presente studio, mentre in figura 8 sono mostrate le localizzazioni proposte nel presente studio rispetto a quelle esistenti in letteratura. i principali risultati ottenuti possono essere così sintetizzati: 205 tab. 3 parametri epicentrali e magnitudo macrosismiche derivati dalla revisione dei terremoti del 1950 e del 1951. epicentral parametres and macroseismic magnitude computed by means of the reappraisal of the 1950 and 1951 earthquakes. terremoto mw imax i0 lat n lon e azimuth lxw (km) 05/09/1950 5.9±0.2 viii viii 42.538 13.390 91.5±18 10.7x7.4 08/08/1951 5.2±0.2 vii vii 42.524 13.436 studio macrosismico del terremoto del gran sasso ... il già citato incremento qualitativo e quantitativo dell’informazione sugli eventi, e quindi l’aumento significativo del livello di conoscenza. al termine dello studio i punti di piano quotato, che sono la fotografia dell’impatto del terremoto sul territorio, risultano triplicati rispetto a quanto noto finora in letteratura per entrambi gli eventi. rispetto al lavoro di di filippo e marcelli (1951), e conseguentemente a cpti (cpti04), l’area dei massimi effetti del terremoto del 1950 viene ridimensionata nell’estensione e risulta decisamente orientata in direzione circa eo, tra le province di l’aquila e teramo. il terremoto dell’8 agosto 1951, nonostante il notevole miglioramento della base informativa, resta poco vincolato. il set di dati è abbastanza disomogeneo, da una parte per effetto dell’oggettivo cumulo dei danni, dall’altra per l’uso, in ambito amministrativo, di indicare l’insieme dei danni subiti a seguito di più eventi (sismici e non). l’impossibilità di distinguere tra gli effetti dei due terremoti, può aver portato ad una sovrastima del danno in alcune località danneggiate nel 1951. la localizzazione del terremoto del 1951 proposta in questo studio è molto prossima a quella del terremoto del settembre 1950, concordemente con quanto mostrano i piani quotati dei due eventi. in sintesi la scossa dell’agosto 1951 si può configurare come una forte replica dell’evento del 1950, avvenuta ad 11 mesi dalla scossa principale, e quindi riferibile ad uno stesso sistema di sorgenti causative. l’intensità massima di questo terremoto viene leggermente ridimensionata, passando da vii-viii a vii. per quanto riguarda gli aspetti sismotettonici, risulta, dalla distribuzione degli effetti e dalla loro modellazione con l’algoritmo boxer (gasperini et al., 1999), una probabile origine su una sorgente sismogenetica con direzione all'incirca eo di cui, peraltro, a tutt’oggi non sono state individuate tracce in superficie riconducibili ad attività tettonica recente. d'altronde, la distribuzione del danno su un'ampia area (comprendente anche territori delle province di rieti e di l'aquila) potrebbe spiegarsi con una profondità ipocentrale maggiore di quella generalmente osservata nel caso di forti terremoti appenninici. ciò suggerisce che il terremoto del 1950 possa essere riferito ad una sorgente con direzione ca. eo, tra il lago di campotosto e pietracamela, attiva in un livello strutturale inferiore a quello degli edifici strutturali della laga e del gran sasso. ringraziamenti un particolare ringraziamento va all’ufficio tecnico del territorio di teramo, nelle persone dell’ing. e. ricci, della d.ssa l. di stefano e del sig. p. perozzi, che hanno permesso la consultazione dell’archivio del 206 fig. 8 confronto tra le diverse localizzazioni presenti in letteratura e quelle proposte nel presente lavoro, relative ai terremoti del 5/9/1950 e 8/8/1951. 1) monachesi e stucchi, 1997; 2) gdl cpti, 2004; 3) postpischl, 1985; 4) gasparini et al., 1985; 5) iss, 1950 e 1951; 6) di filippo e marcelli, 1951; 7) ing, 1950 e 1951; 8) presente lavoro. comparison between the different localizations of the 5/9/1950 and 8/8/1951 earthquakes as reported in literature, and as proposed in this issue. 1) monachesi e stucchi, 1997; 2) gdl cpti, 2004; 3) postpischl, 1985; 4) gasparini et al., 1985; 5) iss, 1950 e 1951; 6) di filippo e marcelli, 1951; 7) ing, 1950 e 1951; 8) present study. a. tertulliani et al. genio civile della provincia di teramo, consentendo l’accesso a documentazione altrimenti irraggiungibile. un nostro grazie va anche al dott. adriano 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(2004) seismology and tectonic setting of the 2002 molise, italy, earthquake. earthq. spectra, 20, s23-s27. vannoli p., basili r., valensise g. (2004) new geomorphic evidence for anticlinal growth driven by blind-thrust faulting along the northern marche coastal belt (central italy). jou. of seismol., 8, 297-313. vezzani l., ghisetti f., bigozzi a., follador u., casnedi r. (1998) carta geologica dell’abruzzo alla scala 1:100.000. s.el.ca., firenze. giornali l’avanti di milano 1950 marzo 2-13, settembre 5-19. l’avanti di milano, 1951 maggio 20-30, agosto 3-15. l’avvenire d’italia di bologna, 1950 marzo 3-18, settembre 6-23. l’avvenire d’italia di bologna, 1951 maggio 22-30, giugno 30 – luglio 1, agosto 3-21. corriere del giorno di taranto, 1950 marzo 2-10, settembre 3-20. corriere della sera di milano, 1950 marzo 4-21, settembre 5-21. corriere della sera di milano, 1951 maggio 17-31, giugno 29-30, agosto 1-22. la gazzetta di livorno, 1950 marzo 2-13, settembre 3-30. gazzetta del mezzogiorno di bari, 1950 marzo 2-15, settembre 3-20. gazzetta del mezzogiorno di bari, 1951 maggio 21-30, agosto 3-20. il giornale dell’emilia di bologna, 1950 marzo 2-13, settembre 3-30. il giornale dell’emilia di bologna, 1951 marzo 8-11, maggio 21-30, agosto 2-22, settembre 1-7. il giornale di napoli, 1950 gennaio 1 – dicembre 31. il giornale d’italia di roma, 1950 marzo 4-17, settembre 5-30. il giornale d’italia di roma, 1951 marzo 7-11, maggio 18-31, giugno 27 – luglio 2, agosto 2-15, 17-22, settembre 1-8. il giornale del pomeriggio quotidiano indipendente del mezzogiorno di napoli, 1950 marzo 2/3 – 13/14, settembre 2/3 – 29/30. il giornale del pomeriggio quotidiano indipendente del mezzogiorno di napoli, 1951 marzo 7/8 – 8/9, maggio 7/8-8/9, 21/22-30/31, giugno 28/29 – luglio 2/3, 18/19 – 21/22, agosto 1/2-settembre 8/9. l’italia di milano, 1950 marzo 2-14, settembre 3-22. la libertà d’italia di roma, 1950 marzo 2-14, settembre 5-20. il mattino di napoli, 1950 settembre 3-25. il mattino di napoli, 1951 marzo 8-11, maggio 20-30, agosto 2-21. il mattino dell’italia centrale di firenze, 1950 marzo 221, settembre 3-25. il mattino dell’italia centrale di firenze, 1951 maggio 16-31, giugno 28-30, agosto 2-25. il messaggero di roma, 1950 marzo 2-16, settembre 530. il messaggero di roma, 1951 marzo 8-11, maggio 2031, agosto 1-23, settembre 1-8. il momento di roma, 1950 maggio 21-23, settembre 130. il momento di roma, 1951 marzo 8-10, maggio 20-26, agosto 2-22. il momento sera di roma, 1950 marzo 2-20, settembre 3-26. il momento sera di roma, 1951 marzo 6-11, maggio 20-31, giugno 28-30, agosto 2-23, settembre 1-7. nuova gazzetta del popolo di torino, 1950 marzo 2-15, settembre 3-21 il paese di roma, 1950 marzo 2-20, settembre 5-30. il paese di roma, 1951 marzo 8-11, maggio 21-31, giugno 29 – luglio 1, agosto 2-20, settembre 1-7. il paese sera di roma, 1950 marzo 2-14, settembre 3-30. il paese sera di roma, 1951 marzo 8-10, aprile 20-21, maggio 8, 22-29, settembre 1-7. la nazione di firenze, 1950 marzo 3-18, settembre 5-23. la nazione di firenze, 1951 marzo 8-11, maggio 20-30, giugno 29 – luglio 1, agosto 1-19. la nuova stampa di torino, 1950 marzo 2-21, settembre 3-21. la nuova stampa di torino, 1951 maggio 20 – giugno 2, giugno 29 – luglio 3, agosto 2-23. la nuova stampa sera di torino, 1950 marzo 2/313/14, settembre 2/3settembre 30/ ottobre 1. la nuova stampa sera di torino, 1951 marzo 7/8 – 9/10, maggio 7/8 – 9/10, 21/22 – 30/31, luglio 18/19 – 21/22, luglio 31/agosto 1 – settembre 8/9. il nuovo corriere di firenze, 1950 marzo 2-14, settembre 3-30. l’osservatore romano di città del vaticano, 1950 marzo 2-20/21, settembre 3-20. l’osservatore romano di città del vaticano, 1951 maggio 21/22-27, agosto 3-23. il popolo di roma, 1950 marzo 2-21, settembre 3-22. il quotidiano di roma, 1950 marzo 3-15, settembre 3-20. il quotidiano di roma, 1951 marzo 8-10, maggio 8-29, agosto 2-17, settembre 1-5. il risorgimento – il mattino di napoli, 1950 marzo 2-20. roma di napoli, 1950 settembre 5-30. roma di napoli, 1951 marzo 8-10, maggio 7-8, 23-29, settembre 1-7. il secolo xix di genova, 1950 marzo 3-12, settembre 522. il tempo di roma, 1950 marzo 2-20, settembre 5-30. il tempo di roma. 1951 marzo 8-12, maggio 21-30, giugno 29 – luglio 1, settembre 1-9. il tirreno di livorno, 1950 marzo 2-14, settembre 3-21. l’umbria di perugia, 1950 luglio 1settembre 30. l’unità di roma, 1950 marzo 2-14, settembre 3-30. l’unità di roma, 1951 marzo 8-10, aprile 21, maggio 929, giugno 30, luglio 20-21, agosto 3-17, settembre 2-6. the rome daily american di roma, 1950 marzo 2-14, settembre 3-20. voce adriatica di ancona, 1950 marzo 2-20, settembre 5-30. voce adriatica di ancona, 1951 marzo 8-11, maggio 20-31, giugno 29 – luglio 1, agosto 2-25, settembre 110. 209studio macrosismico del terremoto del gran sasso ... documenti di archivio archivio centrale dello stato: fondo pubblica sicurezza. categorie annali. busta 100. 1950. sezione ii c3. pubblica calamità. fondo pubblica sicurezza. categorie annali. busta 95. 1951. sezione ii c3. pubblica calamità. fondo pubblica sicurezza. categorie annali. busta 92. 1952. sezione ii c3. pubblica calamità. fondo ministero interni. telegrammi ufficio cifra 1950, settembre, arrivo. archivio di stato de l’aquila: fondo “gabinetto prefettura”, busta 146. xxi. 3b. ag. 1950-1958. archivio di stato di pescara: fondo genio civile: buste 1, fasc. 22. fondo genio civile: buste 7, fasc. 110 bis, terremoti e frane 1915-1959. fondo genio civile: buste 8, fasc. 127, terremoto1950. fondo genio civile: buste 15, fasc. 238, terremoto1950. fondo genio civile: buste 48, fasc. 1330, terremoto. fondo genio civile: buste 63, fasc. 1328, terremoto. archivio di stato di rieti: fondo genio civile. busta 1. atti contabili 1950 rimborso terremoto. fondo genio civile. busta 2. atti vari. fondo genio civile. busta 3. atti vari. fondo genio civile. busta 150. lavori urgenti abitati amatrice e accumoli dopo il terremoto del 1950 – altri comuni. archivio di stato di teramo: fondo gabinetto prefettura. busta 146. xxi. 3b. ag. 1950-1958. fondo prefettura. busta 1 servizio ispettivo terremoto 1950. servizio ispettivo nei comuni della provincia. fondo prefettura. busta 12 pubblicazione mensile l’eco di san gabriele. archivio del genio civile di teramo: i documenti consultati, raccolti in cartelle, non sono attualmente catalogati. segue un elenco di cartelle consultate nel quale viene indicata la dicitura presente sul dorso delle cartelle medesime. basciano. t. 50. dal n. 1 al -. pratiche istruite. bisenti. terremoto 5-9-1950. legge 1-10-1951, n. 1133. pratiche istruite dal n. 1 al. campli, arsita. terremoto. t. 50, pratiche istruite. campli. terremoto 5-9-1950. legge 1-10-1951, n. 1133. pratiche istruite dal n. 1 al n. 60. campli. terremoto 5-9-1950. legge 1-10-1951, n. 1133. pratiche istruite dal n. 61 al n. 130. campli. terremoto 5-9-1950. legge 1-10-1951, n. 1133. pratiche istruite dal n. 131 al n. 180. campli. terremoto 5-9-1950. legge 1-10-1951, n. 1133. pratiche istruite dal n. 181 al n. 260. campli. t. 50. legge 1-10-1951, n. 1133. pratiche istruite dal n. 261. castel castagna t. 50. pratiche accertate dal n. 1 al. istruite. castelli. terremoto 5-9-1950. legge 1-10-1951, n. 1133. pratiche istruite dal n. 1 al -. cellino attanasio. terremoto 1950. pratiche istruite. cermignano. terremoto 5-9-1950. legge 1-10-1951, n. 1133. pratiche istruite dal n. 1 al -. civitella del tronto. terremoto 5-9-1950. legge 1-101951, n. 1133. pratiche istruite dal n. 1 al -. cortino. terremoto 5-9-1950. legge 1-10-1951, n. 1133. pratiche istruite dal n. 3 al -. colledara. terremoto 5-9-1950. legge 1-10-1951, n. 1133. pratiche istruite dal n. 1 al 160. colledara. terremoto 5-9-1950. legge 1-10-1951, n. 1133. pratiche istruite dal n. 160 al. -. colledara. terremoto 5-9-1950. legge 1-10-1951, n. 1133. pratiche istruite dal n. 361al. -. comitato comunale t. 50 (civitella, campli, tossicia, cermignano, colledara, isola, teramo, rocca s. m.). crognaleto. terremoto 5-9-1950. legge 1-10-1951, n. 1133. pratiche istruite dal n. 1 al n. 270. crognaleto. terremoto 5-9-1950. legge 1-10-1951, n. 1133. pratiche istruite dal n. 271 al. -. fano adriano, giulianova, mosciano s. a., montefino. terremoto 5-9-1950. legge 1-10-1951, n. 1133. pratiche istruite. montorio al vomano. terremoto 5-9-1950. legge 1-101951, n. 1133. pratiche istruite dal n. 1 al n. 80. montorio al vomano. terremoto 5-9-1950. legge 1-101951, n. 1133. pratiche istruite dal n. 81 al -. nereto. terremoto 5-9-1950. legge 1-10-1951, n. 1133. pratiche istruite. notaresco, penne s. a., pietracamela. terremoto 5-91950. legge 1-10-1951, n. 1133. pratiche istruite. rocca s. m., silvi, roseto, s. omero, torano, tortoreto. terremoto 5-9-1950. legge 1-10-1951, n. 1133. pratiche istruite. isola gran sasso. terremoto 5-9-1950. domande dal n. 72 al n. 141. isola gran sasso. terremoto 5-9-1950. domande dal n. 311 al-. rocca s. m., pietracamela. terremoto 5-9-1950. torricella s. t. 50. pratiche istruite dal n. 1 al n. 137. tossicia. t. 50. pratiche istruite dal n. 1 al n. 70. tossicia. terremoto 5-9-1950. legge 1-10-1951, n. 1133. pratiche istruite dal n. 1 al n. 150. tossicia. t. 50. pratiche istruite dal n. 151 al-. valle castellana. terremoto 5-9-1950. legge 1-101951, n. 1133. pratiche istruite dal n. 1 al n. 50. varie. terremoto 5-9-1950. archivio dell'istituto nazionale di geofisica e vulcanologia “cartoline sismiche” dell' uff. centr. di meteorologia ed ecologia agraria. de panfilis m., 1950-1959. schede relative a terremoti. (manoscritto). de panfilis m., sec. xx. studio sui terremoti italiani dal 1930 al 1952. (manoscritto). peronaci f., 1950-1959. schede relative a terremoti. (manoscritto). 210 a. tertulliani et al. appendice a piano quotato del terremoto del 5 settembre 1950 (ore 04.08 gmt) località prov lat n lon e i mcs accumoli ri 42,694 13,248 80 arsita te 42,501 13,783 80 bisenti te 42,528 13,802 80 capricchia (amatrice) ri 42,622 13,340 80 colledara te 42,540 13,681 80 fano adriano te 42,552 13,538 80 isola del gran sasso d’italia te 42,501 13,661 80 marana (montereale) aq 42,494 13,222 80 mascioni (campotosto) aq 42,529 13,347 80 nocella (campli) te 42,720 13,677 80 pinaco (amatrice) ri 42,608 13,291 80 poggio cancelli (campotosto) aq 42,561 13,327 80 san giovanni (montereale) aq 42,506 13,276 80 tottea (crognaleto) te 42,553 13,467 80 aringo (montereale) aq 42,554 13,268 75 arischia (l’aquila) aq 42,419 13,342 75 campli te 42,726 13,686 75 campotosto aq 42,558 13,369 75 capitignano aq 42,520 13,301 75 castel castagna te 42,544 13,718 75 castelli te 42,489 13,712 75 cellino attanasio te 42,586 13,859 75 montereale aq 42,522 13,246 75 ortolano (campotosto) aq 42,519 13,423 75 pizzoli aq 42,435 13,303 75 poggio delle rose (cermignano) te 42,571 13,810 75 tarignano (barete) aq 42,455 13,280 75 tossicia te 42,545 13,648 75 amatrice ri 42,628 13,290 70 antrodoco ri 42,414 13,076 70 bagnolo (amatrice) ri 42,631 13,232 70 barete aq 42,450 13,283 70 barisciano aq 42,325 13,592 70 basciano te 42,596 13,740 70 battaglia (campli) te 42,714 13,637 70 borbona ri 42,511 13,137 70 cabbia (montereale) aq 42,483 13,199 70 campovalano (campli) te 42,728 13,663 70 casali di sotto (amatrice) ri 42,602 13,190 70 castelnuovo (campli) te 42,727 13,687 70 cermignano te 42,590 13,794 70 cesaproba (montereale) aq 42,498 13,187 70 civitella casanova pe 42,364 13,889 70 civitella del tronto te 42,771 13,668 70 colleminuccio (teramo) te 42,688 13,716 70 colli (amatrice) ri 42,628 13,273 70 configno (amatrice) ri 42,616 13,258 70 cortino te 42,633 13,543 70 faiano (montorio) te 42,564 13,630 70 faiete (rocca santa maria) te 42,661 13,548 70 farindola pe 42,440 13,823 70 fioli (rocca santa maria) te 42,648 13,472 70 frattoli (crognaleto) te 42,575 13,465 70 illica (accumoli) ri 42,702 13,265 70 leonessa ri 42,568 12,963 70 miano (teramo) te 42,618 13,708 70 molviano (campli) te 42,761 13,718 70 montorio al vomano te 42,584 13,629 70 morge (campli) te 42,739 13,704 70 nerito (crognaleto) te 42,547 13,479 70 padula (cortino) te 42,590 13,473 70 paganica aq 42,358 13,473 70 paranesi (rocca santa maria) te 42,687 13,501 70 pellescritta (montereale) aq 42,508 13,205 70 penna s. andrea te 42,594 13,773 70 penne pe 42,457 13,928 70 pietracamela te 42,523 13,554 70 poggio casoli (accumoli) ri 42,687 13,274 70 poggio d'api (accumoli) ri 42,721 13,295 70 posta ri 42,524 13,097 70 preta (amatrice) ri 42,616 13,346 70 riano (rocca santa maria) te 42,663 13,492 70 rocciano (teramo) te 42,626 13,666 70 roiano (campli) te 42,703 13,637 70 s. benedetto (amatrice) ri 42,627 13,264 70 s. capone (amatrice) ri 42,678 13,288 70 s. giusta (amatrice) ri 42,643 13,253 70 s. tommaso (amatrice) ri 42,685 13,292 70 salle pe 42,177 13,961 70 scorrano (cellino attanasio) te 42,592 13,820 70 sommati (amatrice) ri 42,642 13,309 70 spiano (teramo) te 42,607 13,668 70 teramo te 42,659 13,704 70 terzone (leonessa) ri 42,616 13,070 70 tevere (rocca santa maria) te 42,664 13,490 70 tino (accumoli) ri 42,712 13,252 70 torricella sicura te 42,659 13,656 70 tozzanella (tossicia) te 42,543 13,632 70 valle san giovanni (teramo) te 42,621 13,617 70 ville di fano (montereale) aq 42,531 13,198 70 acquasanta terme ap 42,771 13,411 65 alzano (tossicia) te 42,553 13,643 65 appignano (castiglione m.r.) te 42,544 13,850 65 appignano del tronto ap 42,897 13,668 65 aquilano (tossicia) te 42,556 13,624 65 arquata del tronto ap 42,771 13,296 65 assergi (l’aquila) aq 42,414 13,505 65 azzinano (tossicia) te 42,555 13,632 65 bacugno (posta) ri 42,547 13,126 65 borgo velino ri 42,405 13,059 65 cagnano amiterno aq 42,459 13,232 65 camarda (l’aquila) aq 42,391 13,494 65 carpineto della nora pe 42,333 13,860 65 casale (amatrice) ri 42,669 13,286 65 cassino (accumoli) ri 42,679 13,226 65 castel del monte aq 42,364 13,727 65 catignano pe 42,346 13,951 65 civitaquana pe 42,324 13,899 65 colle moresco (amatrice) ri 42,644 13,234 65 collebrincioni (l’aquila) aq 42,398 13,416 65 collecorvino pe 42,459 14,015 65 colleposta (accumoli) ri 42,661 13,205 65 collespada (accumoli) ri 42,665 13,234 65 domo (amatrice) ri 42,657 13,238 65 elice pe 42,518 13,968 65 floriano (campli) te 42,772 13,751 65 211studio macrosismico del terremoto del gran sasso ... folignano ap 42,820 13,633 65 fonte del campo (accumoli) ri 42,694 13,256 65 grisciano (accumoli) ri 42,732 13,269 65 guazzano (campli) te 42,733 13,644 65 loreto aprutino pe 42,433 13,988 65 macchia (accumoli) ri 42,668 13,257 65 montebello di bertona pe 42,419 13,872 65 ornano grande (colledara) te 42,532 13,652 65 ornano piccolo (colledara) te 42,542 13,656 65 palozza (tossicia) te 42,556 13,674 65 pescosansonesco pe 42,242 13,874 65 pianella pe 42,398 14,050 65 poggio vitellino (amatrice) ri 42,651 13,267 65 preturo (l’aquila) aq 42,377 13,295 65 rio (amatrice) ri 42,664 13,290 65 roccafinadamo (penne) pe 42,476 13,825 65 roccasalli (accumoli) ri 42,655 13,195 65 s. giovanni (accumoli) ri 42,693 13,208 65 santa vittoria (montereale) aq 42,549 13,234 65 sassa (l’aquila) aq 42,352 13,299 65 teora (barete) aq 42,425 13,266 65 trimezzo (cittareale) ri 42,645 13,121 65 valle castellana te 42,737 13,499 65 venarotta ap 42,881 13,493 65 villa celiera pe 42,382 13,860 65 alanno pe 42,294 13,971 60 ascoli piceno ap 42,853 13,578 60 avendita (cascia) pg 42,752 13,050 60 bascianella (colledara) te 42,561 13,694 60 bolognano pe 42,217 13,961 60 brittoli pe 42,316 13,861 60 calascio aq 42,325 13,696 60 canestra (castel sant’angelo) ri 42,394 13,031 60 cappelle sul tavo pe 42,464 14,104 60 caramanico terme pe 42,157 14,003 60 castel di lama ap 42,873 13,707 60 castelnuovo (s. pio delle camere) aq 42,295 13,628 60 castignano ap 42,937 13,622 60 castorano ap 42,898 13,727 60 cesaventre (accumoli) ri 42,661 13,215 60 cittaducale ri 42,386 12,949 60 colli del tronto ap 42,876 13,748 60 colonnella te 42,872 13,866 60 controguerra te 42,855 13,818 60 coppito (l’aquila) aq 42,366 13,344 60 fossa aq 42,296 13,487 60 guardia vomano (notaresco) te 42,636 13,884 60 l'aquila aq 42,356 13,396 60 lucoli aq 42,289 13,350 60 micigliano ri 42,451 13,054 60 montefino te 42,545 13,885 60 morro d'oro te 42,665 13,920 60 navelli aq 42,236 13,729 60 nereto te 42,819 13,817 60 nocciano pe 42,334 13,984 60 norcia pg 42,793 13,094 60 notaresco te 42,659 13,895 60 poggio bustone ri 42,502 12,888 60 roccafluvione ap 42,861 13,475 60 s. omero te 42,788 13,803 60 san demetrio ne` vestini aq 42,288 13,558 60 san valentino in abruzzo citeriore pe 42,233 13,987 60 san vittorino (l'aquila) aq 42,397 13,314 60 sarnano mc 43,035 13,298 60 scafa pe 42,266 14,003 60 scoppito aq 42,372 13,256 60 terracino (accumoli) ri 42,679 13,214 60 tocco da casauria pe 42,213 13,913 60 torano nuovo te 42,825 13,778 60 vestea (civitella casanova) pe 42,388 13,886 60 vicoli pe 42,341 13,898 60 villanuova (accumoli) ri 42,691 13,228 60 cascia pg 42,720 13,014 55 castelvecchio calvisio pe 42,310 13,688 55 castiglione a casauria pe 42,235 13,900 55 cepagatti pe 42,363 14,071 55 citta' sant'angelo pe 42,510 14,060 55 comunanza ap 42,958 13,414 55 concerviano ri 42,322 12,986 55 goriano sicoli aq 42,080 13,775 55 marcetelli ri 42,226 13,046 55 montesilvano pe 42,515 14,151 55 moscufo pe 42,428 14,055 55 offida ap 42,935 13,691 55 palmiano ap 42,899 13,458 55 popoli pe 42,171 13,833 55 pratola peligna pe 42,098 13,875 55 preci pg 42,879 13,039 55 rocca di mezzo aq 42,205 13,521 55 santo stefano di sessanio aq 42,343 13,645 55 spoleto pg 42,732 12,736 55 sulmona aq 42,047 13,928 55 tempera (l’aquila) aq 42,366 13,458 55 turrivalignani pe 42,262 14,029 55 aleggia (amatrice) ri 42,639 13,193 d ancarano te 42,839 13,743 d casteltrione (amatrice) ri 42,624 13,343 d castilenti te 42,534 13,918 d cittareale ri 42,617 13,160 d collegentilesco (amatrice) ri 42,624 13,224 d collepagliuca (amatrice) ri 42,634 13,314 d coronella (cascia) pg 42,637 13,064 d cugnoli pe 42,308 13,933 d cupello (cittareale) ri 42,619 13,157 d faiete (cellino attanasio) te 42,609 13,864 d figino (posta) ri 42,539 13,135 d flamignano (tossicia) te 42,545 13,626 d force ap 42,963 13,491 d forcelle (amatrice) ri 42,644 13,198 d giulianova te 42,753 13,958 d montalto ap 42,988 13,609 d montegallo ap 42,841 13,333 d mosciano s. angelo te 42,750 13,889 d pasciano (amatrice) ri 41,288 13,210 d prato (amatrice) ri 42,634 13,303 d retrosi (amatrice) ri 42,623 13,318 d ripaberarda (castignano) ap 42,923 13,599 d rocchetta (amatrice) ri 42,656 13,287 d ronzano 212 a. tertulliani et al. (castel castagna) te 42.554 13.725 d roseto degli abruzzi te 42,676 14,016 d rotella ap 42,954 13,561 d san giorgio (amatrice) ri 42,634 13,246 d scai (amatrice) ri 42,598 13,231 d silvi te 42,557 14,114 d torrita (amatrice) ri 42,619 13,221 d tortoreto te 42,805 13,914 d vallunga (leonessa) ri 42,580 13,002 d vezzano (cittareale) ri 42,613 13,158 d villa pulcini (leonessa) re 42,596 13,924 d volciano (leonessa) ri 42,581 13,022 d anversa degli abruzzi aq 41,993 13,804 50 avezzano aq 42,033 13,426 50 bugnara aq 42,022 13,862 50 camerano an 43,530 13,551 50 camerino mc 43,135 13,068 50 campello sul clitunno pg 42,820 12,778 50 cannara pg 42,994 12,583 50 cantalice ri 42,466 12,904 50 carsoli aq 42,098 13,084 50 casperia ri 42,338 12,670 50 castelbellino an 43,486 13,145 50 castelnuovo di farfa ri 42,231 12,744 50 chieti ch 42,353 14,169 50 corfinio aq 42,124 13,843 50 fabriano an 43,335 12,905 50 fermo ap 43,160 13,716 50 foligno pg 42,955 12,704 50 forano ri 42,297 12,595 50 gioia dei marsi aq 41,953 13,692 50 labro ri 42,525 12,800 50 macerata mc 43,299 13,452 50 magliano de` marsi aq 42,092 13,363 50 massa martana pg 42,776 12,525 50 matelica mc 43,256 13,009 50 montecassiano mc 43,363 13,436 50 montefalco pg 42,893 12,651 50 morro reatino ri 42,527 12,832 50 nocera umbra pg 43,113 12,788 50 orte vt 42,460 12,385 50 ostra an 43,612 13,158 50 pacentro aq 42,050 13,993 50 pescara pe 42,464 14,214 50 pescina aq 42,025 13,657 50 pettorano sul gizio aq 41,972 13,960 50 piediluco tr 42,536 12,755 50 pineto te 42,608 14,067 50 poggio mirteto ri 42,265 12,686 50 porto civitanova (civitanova marche) mc 43,300 13,733 50 potenza picena mc 43,366 13,621 50 raiano aq 42,102 13,813 50 rieti ri 42,404 12,867 50 ripatransone ap 42,999 13,762 50 rivodutri ri 42,515 12,856 50 rocca di cambio aq 42,235 13,490 50 sant'angelo in pontano mc 43,100 13,398 50 staffolo an 43,432 13,186 50 stimigliano ri 42,299 12,565 50 terni tr 42,561 12,648 50 tione degli abruzzi aq 42,203 13,636 50 toffia ri 42,212 12,752 50 turania ri 42,137 13,009 50 visso mc 42,930 13,088 50 vittorito aq 42,125 13,817 50 agugliano an 43,544 13,388 45 ancona an 43,603 13,507 45 arrone tr 42,583 12,768 45 assisi pg 43,070 12,616 45 farfa (castelnuovo di farfa) ri 42,231 12,744 45 filottrano an 43,434 13,351 45 jesi an 43,522 13,245 45 loreto an 43,439 13,610 45 spello pg 42,992 12,668 45 tolentino mc 43,209 13,283 45 viterbo vt 42,421 12,110 45 barbara an 43,579 13,025 40 bolognola mc 42,993 13,228 40 capistrello aq 41,966 13,391 40 calamari (veroli) fr 41,671 13,487 40 castel colonna an 43,679 13,107 40 citta` di castello pg 43,456 12,239 40 fabro tr 42,863 12,013 40 fano pu 43,837 13,018 40 genga an 43,429 12,935 40 guarcino fr 41,799 13,314 40 mergo an 43,472 13,037 40 monteleone d`orvieto tr 42,917 12,051 40 narni tr 42,517 12,521 40 nespolo ri 42,155 13,070 40 perugia pg 43,106 12,386 40 ripe an 43,671 13,107 40 rocca pia aq 41,932 13,977 40 roma rm 41,895 12,482 40 ronciglione vt 42,291 12,217 40 senigallia an 43,714 13,223 40 subiaco rm 41,925 13,095 40 tuscania vt 42,420 11,869 40 urbino pu 43,726 12,636 40 velletri rm 41,688 12,778 40 scanno aq 41,903 13,881 35 sora fr 41,718 13,613 35 alatri fr 41,726 13,344 30 arpino fr 41,649 13,611 30 ceprano fr 41,544 13,517 30 ferentino fr 41,691 13,254 30 fiuggi fr 41,802 13,224 30 montefiascone vt 42,537 12,030 30 rivisondoli aq 41,870 14,066 30 roccaraso aq 41,847 14,079 30 sarteano si 42,989 11,869 30 chiusi si 43,016 11,948 25 acuto fr 41,791 13,176 20 filettino fr 41,889 13,324 20 frosinone fr 41,635 13,340 20 priverno lt 41,473 13,181 20 alviano tr 42,590 12,297 f amandola ap 42,980 13,357 f attigliano tr 42,515 12,294 f castel di sangro aq 41,784 14,108 f castel gandolfo rm 41,747 12,651 f ficulle tr 42,835 12,066 f monteleone di spoleto pg 42,652 12,953 f orvieto tr 42,719 12,113 f ovindoli aq 42,136 13,516 f palestrina rm 41,836 12,889 f scheggino pg 42,712 12,831 f sellano pg 42,888 12,927 f sigillo ri 42,496 13,081 f todi pg 42,782 12,407 f acquafondata fr 41,544 13,953 nf balsorano aq 41,810 13,561 nf 213studio macrosismico del terremoto del gran sasso ... barrea aq 41,758 13,993 nf calenzano fi 43,861 11,165 nf certaldo fi 43,549 11,041 nf cervaro fr 41,482 13,905 nf chianciano si 43,060 11,832 nf collelongo aq 41,886 13,584 nf empoli fi 43,721 10,947 nf fiesole fi 43,807 11,295 nf finale emilia mo 44,834 11,295 nf latina lt 41,468 12,904 nf pelago fi 43,774 11,504 nf piglio fr 41,829 13,145 nf radicofani si 42,897 11,769 nf rufina fi 43,824 11,486 nf sabaudia lt 41,301 13,027 nf sezze lt 41,500 13,060 nf terelle fr 41,554 13,779 nf terracina lt 41,288 13,233 nf vaglia fi 43,907 11,282 nf vinci fi 43,786 11,926 nf appendice b piano quotato del terremoto dell’8 agosto 1951 (ore 19.56 gmt) località prov lat n lon e i mcs cagnano amiterno aq 42,459 13,232 70 isola del gran sasso d`italia te 42,501 13,661 70 nerito (crognaleto) te 42,547 13,479 70 paganica (l’aquila) aq 42,358 13,473 70 arischia (l’aquila) aq 42,419 13,342 65 barete aq 42,450 13,283 65 barisciano aq 42,325 13,592 65 campli te 42,726 13,686 65 campotosto aq 42,558 13,369 65 canzano te 42,646 13,804 65 capitignano aq 42,52 13,301 65 civita di bagno (l’aquila) aq 42,308 13,445 65 montereale aq 42,522 13,246 65 sassa (l’aquila) aq 42,352 13,299 65 senarica (crognaleto) te 42,547 13,515 65 teramo te 42,659 13,704 65 bellante te 42,743 13,806 60 cascia pg 42,720 13,014 60 cermignano te 42,590 13,794 60 cortino te 42,633 13,543 60 l’aquila aq 42,356 13,396 60 pizzoli aq 42,435 13,303 60 rocca santa maria te 42,661 13,548 60 san vittorino (l’aquila) aq 42,397 13,314 60 amandola ap 42,980 13,357 55 basciano te 42,596 13,740 55 colonnella te 42,872 13,866 55 ferentillo tr 42,620 12,791 55 spinetoli ap 42,888 13,773 55 castelli te 42,489 13,712 d cellino attanasio te 42,586 13,859 d colle paganica (montereale) aq 42,507 13,268 d mascioni (campotosto) aq 42,529 13,347 d poggio cancelli (campotosto) aq 42,561 13,327 d valle castellana te 42,7367 13,499 d alanno pe 42,294 13,971 50 amatrice ri 42,628 13,290 50 antrodoco ri 42,414 13,076 50 ascoli piceno ap 42,853 13,578 50 atri te 42,580 13,978 50 cannara pg 42,994 12,583 50 castilenti te 42,534 13,918 50 cittaducale ri 42,386 12,949 50 fano adriano te 42,552 13,538 50 foligno pg 42,955 12,704 50 montelparo ap 43,018 13,536 50 moscufo pe 42,428 14,055 50 muccia mc 43,081 13,044 50 preci pg 42,879 13,039 50 rivodutri ri 42,515 12,856 50 san demetrio ne' vestini aq 42,288 13,558 50 sulmona aq 42,047 13,928 50 terni tr 42,561 12,648 50 trevi (perugia) pg 42,877 12,746 50 venarotta ap 42,881 13,493 50 castignano ap 42,937 13,622 45 giove (terni) tr 42,509 12,324 45 nespolo ri 42,155 13,070 45 pineto te 42,608 14,067 45 rieti ri 42,404 12,867 45 acquasparta tr 42,690 12,546 40 ancona an 43,603 13,507 40 arrone tr 42,583 12,768 40 campello sul clitunno pg 42,820 12,778 40 castelbellino an 43,486 13,145 40 civitella del tronto te 42,771 13,668 40 falerone ap 43,107 13,472 40 fermo ap 43,160 13,716 40 guardea tr 42,622 12,298 40 lugnano in teverina tr 42,573 12,331 40 macerata mc 43,299 13,452 40 matelica mc 43,256 13,009 40 mompeo (rieti) ri 42,248 12,753 40 monterubbiano ap 43,085 13,716 40 narni tr 42,517 12,521 40 pescara pe 42,464 14,214 40 piedipaterno (vallo di nera) pg 42,769 12,863 40 roma rm 41,895 12,482 40 subiaco rm 41,925 13,095 40 pratola peligna pe 42,098 13,875 35 alatri fr 41,726 13,344 30 assisi pg 43,070 12,616 30 rocca di papa rm 41,760 12,710 30 tuoro sul trasimeno pg 43,208 12,071 25 firenze fi 43,777 11,249 20 vallombrosa (reggello) fi 43,731 11,558 20 avezzano aq 42,033 13,426 f castel del monte aq 42,364 13,727 f fiuggi fr 41,802 13,224 f norcia pg 42,793 13,094 f perugia pg 43,106 12,386 f pilonico materno (perugia) pg 43,035 12,270 f spoleto pg 42,732 12,736 f viterbo vt 42,421 12,110 f 214 ms. ricevuto il 3 ottobre 2006 testo definitivo ricevuto il 23 gennaio 2007 ms. received: october 3, 2006 final text received: january 23, 2007 a. tertulliani et al. imp.orrš& submerged geomorphosites in the marine protected areas of sardinia (italy): assessment and improvement paolo orrù1, valeria panizza2 & antonio ulzega1 1dipartimento di scienze della terra, università di cagliari 2dipartimento di teorie e ricerche dei sistemi culturali, università di sassari abstract: p. orrù et al., submerged geomorphosites in the marine protected areas of sardinia (italy): assessment and improvement. (it issn 0394-3356, 2005). inside the studies conducted around the theme of the improvement of the italian geological and geomorphological heritage, studies undertaken in the ambit of different research projects and working groups, we want, with this work, to experiment and to verify the applicability of the methodologies of assessment and census of the sites of geological and geomorphological interest in submerged areas. this with the aim to gather the most greater number of possible data on the characteristics of the physical submerged resources in protected sea areas, both for scientific purpose and for a possible fruition by the public of the scuba divers. further intent is, in fact, that to drive the "tourist" toward a more aware and global knowledge and perception of the underwater world, in all the aspects of any cultural interest, and not only for those aspects tied up to the complex of the living organisms. the experimentation of the methodology and the study on two protected sea areas of the island of sardinia (italy) is proposed: the protected sea area of c. carbonara and the protected sea area of c. caccia. riassunto: p. orrù et al., geomorfositi sommersi nelle aree marine protette della sardegna (italia) . (it issn 0394-3356, 2005). all’interno degli studi condotti intorno al tema della valorizzazione del patrimonio geologico e geomorfologico del territorio italiano, studi intrapresi nell’ambito di diversi progetti di ricerca e gruppi di lavoro, si è voluto, con questo lavoro, sperimentare e verificare l’applicabilità delle metodologie di valutazione e censimento dei siti di interesse geologico e geomorfologico in aree sommerse. questo al fine di raccogliere il maggior numero di dati possibili sulle caratteristiche delle risorse fisiche sommerse di aree marine protette, sia a fini puramente scientifici che per un’eventuale fruizione rivolta al pubblico dei subacquei. ulteriore intento è, infatti, quello di guidare il “turista” verso una percezione e conoscenza più consapevole e globale del mondo subacqueo, in tutti gli aspetti di interesse culturale, inteso nel senso più ampio, e non solo per gli aspetti legati al complesso degli organismi viventi. si propone lo studio e la sperimentazione della metodologia a due aree marine protette dell’isola di sardegna (italia): l’area marina protetta di c. carbonara e l’area marina protetta di c. caccia. key words: geomorphosites, continental shelf, palaeo-shorelines, tourism, sardinia. parole chiave: geomorfositi, piattaforma continentale, paleo-linee di riva, fruizione turistica, sardegna. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 167-174 1. foreword the present paper has the purpose to extend the already very well established growing interest in geological and geomorphological heritage of continental contexts also to the submerged areas. the marine environment is normally frequented for its biological aspects, and even experienced divers generally have no knowledge at all of the physical aspects, such as geology and geomorphology, that sustain underwater life. more and more attention has been focussed on geological and geomorphological heritage in the past few years, leading to several researches in the framework of conservation projects, both at administrative and at scientific level involving national and international research groups. associations such as progeo (european association for the conservation of the geological heritage) have the purpose of promoting the knowledge and the conservation of the geological heritage at european level, and started the compilation of a list of european geosites. the project geosites of the international union of geological sciences (iugs) started shortly after, with the scope of making an inventory for the collection of all data on the most important geological sites of europe and of the world. this last project has stimulated the formation of other working groups and research projects all aiming at elaborating and improving methodologies for the inventory, selection and assessment of geological and geomorphological sites. this research fits in the framework of such studies that have developed also in italy in the past ten years, and has been performed inside the national project cofin 2001-2003 “geosites in the italian landscape” and in the working group “geomorphosites” of the international association of geomorphologists (iag). the aim is to make the enjoyment of the submerged resource less controlled by emotion and more by awareness through the realisation of guided diving routes. in fact, the submarine environment, more than the terrestrial one, is typically characterised by an emotional approach. to have a complete interpretation of the landscape one needs decoding instruments (bini & poli, 2003), thus capable of guiding the awareness of the entire system through its most significant variables once an evolutional context is identified (panizza & piacente, 2003). a scientific approach aiming to the enjoyment of 168 p. orrù et al. the submerged geomorphological landscape is proposed in this paper taking as example a selection of sites. a geomorphosite, according to panizza m. (2001) is “a landform with particular and significant attributes that qualify the site as part of the cultural heritage (latu sensu) of a territory”. according to this definition the value of a geomorphosite comprises also their relationship with other significant components of their environment, such as biological, historical, archaeological etc. the preliminary study, analysis and census of the most significant sites is followed by the realisation of guided diving routes that give the opportunity to enjoy the different aspects of geology, geomorphology, biocoenosis etc.. similar guided diving routes are lacking in other european marine protected areas where biological themes are normally put in evidence, leaving geology and geomorphology as simple “containers”. it is our purpose to give a central role to these last aspects for the interpretation of the submarine environment that, in many cases, is much more conservative than the terrestrial one. in the submerged environment, in fact, relict landforms, testifying past geological and geomorphological events or paleo-environments, and direct consequences of human interaction are usual better conserved than in a continental environment. in planning submarine diving routes one needs to consider the technical preparation of the divers, differentiating routes according to the different diver’s licences. thus, the choice of the sites is limited to the depth of 40 meters, on the continental shelf, where the variety of present landforms, derived from submarine processes and in equilibrium with the present sea level, and relict landforms, related to continental processes or in equilibrium with sea level low stands, is highest. also the biological aspects are the most interesting and varying in the same ambit, because directly correlated to the variety of the local morphological conditions. the past negative experiences documented in marine reserves of the mediterranean (ribera siguan, 1990; ramos, 1990) and in the tropics (hawkins & roberts, 1993) suggest to devote special attention to the aspects related to the capacity of absorbing tourist presence, the so-called carrying capacity, of certain extremely vulnerable submarine environments (agardy, 1993; di gregorio, 1993). two protected marine areas of sardinia have been chosen for the experimentation of the methodology: the marine protected areas of capo carbonara (south-east sardinia) and of capo caccia (north-west sardinia) (fig. 1). both areas are very different for what concerns geology and present and relict geomorphology. these differences, creating a wide variety of micro-environments, also cause different biocoenosis, adding interest and value to the single sites. 2. methodology 2.1 surveying methods the mapping of the landforms and of the biocoenosis (peres & picard, 1964) has been done by the integrated overlapping of data acquired with different methods: for the shallow underwater environments remote sensing data have allowed to distinguish the limits of the submerged beaches and the rocky coastal abrasion platform up to a depth of 10 meters. satellite images also allow to map the areas occupied by posidonia oceanica up to 20 meters of depth. the survey of submerged landforms with geophysical techniques has involved the proximal continental shelf at depths between 20 and 40 meters, using vertical and side scan sonar technology. these remote sensing data have been verified by direct underwater surveys. the specific oceanographic survey has been planned on the ground of the nautical maps of the italian “istituto idrografico della marina” at scale 1:100.000 and 1:50.000. the main problem in surveying and mapping submerged geomorphosites is the construction of reliable and detailed bathymetric maps in scale 1:10.000, maps that can be also the basis for the tourist and diver’s enjoyment. the following step is the preparation of a geomorphological map that represents the coast and the continental shelf using criteria and legends proposed by the geological service of italy for the geomorphological map of italy in scale 1:50.000. fig. 1 location of the study areas. localizzazione delle aree di studio. 2.2 selection and cataloguing by means of a methodology of selection, study and cataloguing of the geomorphosites, adopted in the framework of the specific research projects mentioned earlier in this paper, several sites have been identified in both study areas. the considered sites possess one or more attributes of scientific value as an essential condition for their choice (panizza 1988; panizza & piacente, 1989; carton et al., 1994; panizza & piacente, 2003). the sites, because of the genetic characteristics of the internal continental shelf, practically always have a high paleo-geomorphological significance besides their ecological valence related to the hosted biocoenosis. in both study areas sites with the following significant valences have been chosen (panizza & piacente, 1989): model of geomorphological evolution (wave notch, karstic caves, slope of the cliff etc.); didactic exemplarity (fault cliff, abrasion platform, landslides, sand waves, etc.); paleo-geomorphological testimonial (inselberg and tor formed in continental environment, beach rocks, tafoni, carbonate precipitation forms such as stalactites and stalagmites, etc.); ecological valence (almost vertical walls, tafoni and karstic cavities with development of biocoenosis with porifera and coelenterata, isolated reliefs with concentration of big lair fish). the sheet file, elaborated in the framework of the national project “geosites in the italian landscape” and realised by the national geological service and the centre of documentation on geosites of genova university, has been used for the cataloguing of the sites (fig. 2). this sheet file, being made for the documentation of continental geosites, has been adapted and revised in some of its contents. the location of the site can be done referring to the new edition of the topographical map of italy if the detail of bathymetry is sufficiently reported, otherwise the bathymetric maps of the italian “istituto idrografico della marina” or other bathymetric documents can be used as long as the type of map is referred to in the sheet file. maximum and minimum depth are indicated to know the relative depths to which one has to dive to appreciate the qualifying elements of the chosen site. given the strict interdependence between biocoenosis and geodiversity, this last intended as the variety of morphological and lithological micro-conditions, the submarine geomorphosite will present, in the majority of cases, a secondary naturalistic or ecological interest indicated in the sheet file in field c. other fields of compilation, such as the field i related to the type of soil in the original sheet file, have been enlarged to be able to contain the necessary information of certain marine environments, such as the type of seafloor: sandy, pebbly, outcropping rocks etc.. 3. marine protected area of capo carbonara the marine protected area of capo carbonara is located in the south-eastern most part of sardinia and is comprised in the commune of villasimius in cagliari province. the promontory of capo carbonara closes the gulf of cagliari to the east with the islets of cavoli and serpentara. the crystalline basement of south169submerged geomorphosites in ... east sardinia is tectonically strongly deformed according to nw-se lineations of alpine age (cherchi & montadert, 1984). the same tectonic imprint strongly influences the coastal and the submarine landscape. the development of the coastline is characterised by iso-oriented promontories, dominated by capo carbonara, all of which are aligned along main veins (brotzu & morbidelli, 1974); the promontories of the eastern sector comprise a system of small pocket beaches. the continental shelf is characterised by an eastern sector controlled by tectonic n-s movements and a western sector guided by nw-se alignments, separated by the promontory of capo carbonara. the first researches on the south-eastern continental shelf of sardinia concerned the types of margins and the characteristics of the sedimentary units (lecca et al., 1979). the head of the simius canyon rises up on the border of the continental shelf, southeast of the islet of cavoli, along a nw-se direction (lecca et al., 1998). ancient coastlines, recognisable in beach rocks, have been found at depths of 45 meters (ulzega et al., 1984; orrù et al., 1997). the submarine landscape of the villasimius area is dominated by the outcropping of granite rocks and associated magmatic differentiated rocks; the morphological asset is organised in a system of irregular surfaces that develop at different depths. an ancient, irregular and gently seawards inclining surface of continental erosion is visible at depths between 40 and 60 meters, characterised by relict landforms such as tor and inselberg on the shallows of berni, of libeccio and on the isolated relief south of the islet of serpentara. these landforms are difficult to date, even though their state of evolution does testify very long time of formation, probably related to a pre-quaternary period characterised by warm-wet climate and a much lower sea level than today. more rapidly evolving continental landforms, presently underwater, are the large-sized tafoni with chambers characterised by sub-spherical roofs; these landforms can frequently be found in the whole area at depths comprised between 15 and 30 meters. an irregular erosion surface fossilised by aeolian sandstones with cross-bedding, from a sedimentological point of view similar to the aeolian deposits of the actual coastline, is reported at 15 meters depth in the southern bay of the islet of cavoli (palmerini, 1967). other parts of almost horizontal surfaces with homogeneous characteristics are concentrated in some precise bathymetric intervals: an abrasion surface at average depth of 25 meters is reported at capo boi, in the shallows of s. caterinia, of libeccio and of berni. active marine abrasion surfaces at depths between 1 and 3 meters border all the main promontories of the study area. the veins of acid rocks arise from these surfaces due to differential erosion. many sandy-conglomerate beach-rocks have been preserved on the seafloor of villasimius both on the proximal and the external continental shelf: these are ancient shorelines related to the holocene sea level rise. the deepest of these is located to the north of the islet of serpentara, at 45 meters depth; this ancient shoreline is particularly important because it can be retraced along most of the eastern continental shelf of 170 sardinia right up to the strait of bonifacio (ulzega et al., 1984). the posidinia oceanica meadow colonises most of the upper continental shelf of carbonara for a total surface of over 40 square km. coralligenous or precoralligenous biocoenosis, dominated by gorgonia, coelenterata in general, porifera and calcareous algae facies, develop especially on the cliffs or on isolated blocks. the deepest biocoenosis are represented by carbonate constructions of algae with pseudolithophyllum expansum. the littoral bench of the vermetid dendropoma is the only animal biological construction represented in the area and found in the northern part of the islet of cavoli; this gastropod formation is very important being an indicator of the most recent variations of sea level. this is the northernmost occurrence of this kind of biological constructions along the italian coasts; similar formations are well fig. 2 excerpt of the sheet file for the inventory of the italian geosites, compiled for the cataloguing of the cave of nereo (c. caccia, alghero). stralcio di scheda per l’inventario dei geositi italiani, compilata per la catalogazione della grotta di nereo (c. caccia, alghero). p. orrù et al. 171 developed along the northern coasts of sicily. the submarine surveys have allowed to map the main biotic communities in detail (meinesz et al., 1983), putting also in evidence the tight existing interrelations between geomorphological characteristics, distribution of morpho-sedimentary units and main benthic biocoenosis. in the framework of the geomorphological context of the continental shelf of carbonara the site named “shallow of berni” has been selected according to the previously described criteria. this isolated almost surfacing granite relief is located offshore the simius bay, in an axial position respect to the channel between capo carbonara and the islet of cavoli. the shallow of berni is a tor represented by a central column of 15 meters height, circled by residual peaks and accumulations of big sub-spheroidal tafoni (fig. 3). the ancient, gently seawards inclining continental erosion surface, characterised by a biocoenosis of posidonia oceanica and coralligenous platform reefs with red algae (pseudolithopyllum expansum), locally crops out at the foot of the relief. the dominating valence of this selected geomorphosite is the paleo-geomorphological and paleogeographical one, related to the evolution of a broad continental erosion surface now submerged. also the biological valence related to the strong currents and to the related circulation of nutrients is very important. another important aspect is related to the historical and cultural importance of this site, being a privileged embarkation point for horses and herds from sardinia to other beaches of the mediterranean starting from the roman imperial period; this practice continued during the medieval and arrived up to the xix century. nowadays an exceptional concentration of shipwrecks and ceramics of different ages together with animal remains are found. 4. protected area of capo caccia the promontory of capo caccia is located in northwest sardinia, in the so-called nurra of alghero, in the territory of the commune alghero in sassari province. is characterised by high cliffs that arrive at heights of 170 meters a.s.l., forming, in its southern extremity, a n-s directed promontory that closes the broad gulf of porto conte to the southwest. capo caccia is part of the regional natural park of porto conte, instituted in 1999 and comprising, aside the promontory, the entire peninsula, with the hilly complex of monte timidone (361 m), the bay of porto conte and, towards the east, the vast territory that extends from monte doglia (436 m) up to the rocky promontory of punta giglio. the marine protected area of national interest “capo caccia-porto conte-punta giglio” has been instituted recently and includes the near shore seafloor of the regional natural park up to a depth of 50 meters. the whole mesozoic carbonatic sequence crops out in the area, except for some local quaternary deposits and the permian-triassic alluvial plain sediments (verrucano sardo, pecorini, 1962) that characterise the coastal strip north of cala viola. this mesozoic sequence represents a general transgression of this part of sardinia with the deposition of carbonate platform sediments characterised by limestones, dolomitic limestones, marly limestones and marls. the platform sedimentation is interrupted by a bauxite deposition during meso-cretaceous, representing a period of emersion and thus continental tropical or sub-tropical warm-wet climatic conditions (carmignani et al., 2001). the thick carbonatic sequences of neritic environment of upper cretaceous, attaining their maximum thickness of 140 meters at capo caccia, evidence a general return to typical marine conditions (carmignani et al., 2001). the main tectonic alignments mostly of tertiary age are directed n-s and nwse (cherchi & montadert, 1984) and guide the evolution of the morphologies characterised by scarps in the internal areas and also control the high cliffs that are typical of the entire coastal perimeter of capo caccia (federici et al., 1999; ginesu, 1999). from a geomorphological point of view the whole area is characterised by a wide variety of landforms deriving from intense and differentiated fossil and still active processes of karst dissolution. for what concerns the fig. 3 simius bay – berni shallow. picture of the bottom at -15 m. residual pinnacles and sub-spherical blocks on the border of a tor relief; a network of joints in which archaeological remains are concentrated and conserved develops at the foot of the ridge. baia di simius secca dei berni . foto del fondo a -15 m. guglie residuali e blocchi sub-sferoidali ai bordi del rilievo a tor; alla base delle cornici si sviluppa un reticolo di diaclasi, luogo di concentrazione e di conservazione dei materiali di interesse archeologico. submerged geomorphosites in ... 172 promontory of capo caccia the impressive cliffs that characterise its entire profile and continue along the whole western coast of the peninsula, reaching a height of 203 meters, show active processes of retreat and several levels of wave notches related to the quaternary sea level variations. many and complex natural caves are clearly visible along the calcareous cliffs, and many of these are accessible only by diving. a first karstic phase is related to the continental mesocretaceous period, enhanced by the wet and warm climatic conditions (federici et al., 1999). a paleokarst phase can thus be hypothesised along faults and discontinuities during cretaceous, before the upper cretaceous transgression and marine sedimentation (mucedda et al., 1997). other karst dissolution phases followed the first one in the geological and climatic history of sardinia, and the presence of many caves along the coast testifies a long-during dissolution enhanced by an intense underground circulation (ginesu, 1999). in this particular geological and geomorphological context the methodology for selecting and cataloguing geomorphosites has been directed towards the many submarine caves present along the cliffs of the capo caccia promontory. the nereo cave has thus been chosen, for its genetic characteristics, for its importance in the reconstruction of paleo-environments, for the variety and the differentiation of its ecosystems and for its potential to attract tourists, many of the attributes that can give value to this geological and geomorphological site (panizza & piacente, 2003). the nereo cave is located at the foot of the promontory of capo caccia, hosted in white and compact limestones of lower cretaceous in which many of the caves of the promontory are formed. the cave was discovered in 1957 by two local divers and has become famous especially for the presence of many colonies of red coral (corallium rubrum). today, unfortunately, this coral is present only in small groups in the less exposed sites of the cave (chessa et al., 1991). only recently the cave has been thoroughly explored and surveyed for a total development of more than 400 meters, along a complex series of chambers, tunnels and shafts. the nereo cave, that represents the biggest sea cave of the mediterranean, has 7 communicating entrances located at variable depths between 8 and 31 meters, of which only three can be defined as main entrances (mulas, 2000). the cave, in this case, has a mixed origin, being formed by a combination of karstic and marine erosion phenomena (chessa et al., 1999). the deepest entrance (-31 meters) opens towards the north, corresponding to the cala del sommergibile, and leads into a big chamber which floor is covered with rocks fallen from the roof and sandy patches. many tunnels start from here and lead towards the other two entrances, one to the west one to the south. the most external parts of these tunnels often show clear pebbles modelled by marine abrasion, sandy sediments and fragments of sea shells. from the biggest chambers and from the main branches departs a labyrinth of tunnels and fissures, not always accessible, some of which develop vertically (sumps) and open in subaerial and concretioned parts of the cave, with stalactites and stalagmites (mulas, 2000; chessa et al., 1999). these parts of the cave have been explored only very recently and are accessible only to expert and well equipped cave divers. also the western entrance, at 18 meters depth, leads into a very big chamber characterised by big blocks at the entrance forming a beautiful sight. from here one can proceed towards the south to gain the third entrance that has two openings one above the other, respectively at 9 and at 14 meters depth. one of the few remaining colonies of red coral can be seen in correspondence of this entrance, towards the left. the big blocks, with differing degree of biological colonisation, present at the different entrances are the proof that the cliffs are still retreating and subjected to sporadic rockfall. furthermore, a deep wave notch can be seen at the foot of these active cliffs. aside the evident valence of the cave as a model of geomorphological evolution, the dimensions of the littoral-karstic phenomenon and its relationships with the actively retreating of the cliffs, together with the paleo-geomorphological meaning of this site is of great value and significance. in fact, erosion forms related to the sea level variations and stalactite-stalagmite constructions with submarine and subaerial cements are well conserved. the presence of numerous colonies of coelenterata (ceriantus membranaceus e corallium rubrum), typical of sciophilous environments, gives this site also a great ecological valence. conclusions the tourist offer in marine protected areas and marine national parks in the mediterranean, especially in the submarine field, is related almost exclusively to the ecological valences and the value of the different submerged areas is essentially related to the level of biodiversity. exception is made for some protected areas of sicily, of greece and of turkey where cultural aspects dominate, related to the presence of important submerged archaeological resources. the submerged landscape has thus been relegated to the role of “container” for the other valences. in this paper a different role of the submerged landscape is put forward, following the recently introduced and proposed concepts (panizza, 2001; panizza & piacente, 2003; piacente & poli, 2003) and the application of new methodologies for the selection and the assessment of environmental assets with a high geomorphological relevance. the examples described in this paper, in fact, show that this submerged landscape explains itself in an autonomous way, by its own physical character of great suggestion and by its history and evolution visible in the mosaic of landforms and deposits that compose a geomorphological and paleo-geomorphological picture (fig. 4). also the potentiality expressed by the integration with biological and historical-cultural valences is of great interest. in making submerged geomorphosites enjoyable one has to keep in mind the risk of damaging these sites, especially in the case of very fragile landforms and microforms (tafoni and residual granite blades, wall concretions and stalactites in natural caves, etc.). it is thus very important to plan and control the visits on the basis of a detailed analysis of the carrying capacity of the sites. p. orrù et al. references agardy m. 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(1999) geositi testimoni del tempo. regione emilia romagna. edizioni pendragon, bologna. r a m o s a. (1990) the marine reserve of nueva tabarca island: management aspects (alicante, spain). atti del conv. intern. sui parchi e le riserve marine del mediterraneo, s. teodoro, 28/30 aprile 1989. ed chiarella, sassari. ribera siguan m. a. (1990) parques y riservas marinas en espana. atti del conv. intern. sui parchi e le riserve marine del mediterraneo, s. teodoro, 28/30 aprile 1989. ed chiarella sassari. servizio geologico d’italia (1961) carta geologica d'italia a scala 1:100.000, f. 192 alghero. ulzega a., leone f. & orrù p. (1984) late quaternary sea-level evidence in sardinia the submerged beach-rock of serpentara. inter. sympos. on late quaternary sea-level changes and coastal evolution, mar de plata, argentina. 174 p. orrù et al. imp.rosskopf& indagini geoarcheologiche integrate nel molise centrale (italia meridionale): il ponte romano di tufara carmen maria rosskopf 1, gianfranco de benedittis 2 & paolo mauriello1 1 dipartimento di scienze e tecnologie per l’ambiente e il territorio, università degli studi del molise rosskopf@unimol.it; mauriello@unimol.it; 2 facoltà di scienze umane e sociali, università degli studi del molise cfbyad@tin.it riassunto: rosskopf et al., indagini geoarcheologiche integrate nel molise centrale (italia meridionale): il ponte romano di tufara. (it issn 0394-3356, 2007). sebbene il molise si stia rivelando una regione di straordinaria ricchezza archeologica, le conoscenze ad oggi circa la distribuzione spazio-temporale degli insediamenti e delle relative manifestazioni economico-culturali sono del tutto lacunose. ciò pone in chiara luce la difficoltà di mettere i dati archeologici in relazione ai contesti e cambiamenti ambientali, e di valutare l’influenza di questi ultimi sulle vicende umane. il presente lavoro illustra una delle prime esperienze di indagine geoarcheologica integrata effettuate nell’area del molise centrale. tale indagine si è basata su un approccio integrato di analisi archeologiche, geofisiche e geomorfologiche. la struttura che è stata indagata è localizzata nella medio-bassa valle del fiume fortore in località pesco del ponte, comune di tufara (italia meridionale), ed è emersa solo di recente a seguito di un evento alluvionale avvenuto nel gennaio del 2003. si tratta di resti di un ponte che è possibile riferire, in base alla tecnica di lavorazione dei blocchi utilizzati, all’epoca tardo-repubblicana (ii i sec. a.c.). sui resti romani si sovrappongono lacerti in muratura e malta che sono da riferire ad un rifacimento della struttura in epoca medioevale. si tratta di una scoperta molto interessante considerando che l’esistenza di tale ponte è di forte sostegno all’ipotesi, supportata anche da altri dati, della presenza, già in epoca repubblicana, di una strada che attraversava l’alveo del fortore proprio all’altezza del ponte. in base all’analisi delle fonti letterarie e storico-cartografiche, tale strada potrebbe essere stata una delle due principali arterie che trovavano nel centro dell'antico abitato di saepinum il loro punto d'incontro. allo scopo di valutare la prosecuzione nel sottosuolo della stessa struttura del ponte e/o della collegata viabilità sono stati effettuati dei profili geoelettrici dipolari che hanno consentito la restituzione di sezioni di probabilità di occorrenza di anomalie di resistività nel sottosuolo a varie profondità. le anomalie riscontrate indicano chiaramente la presenza nel sottosuolo, a poca profondità, di una struttura che va presumibilmente identificata con la prosecuzione del ponte. le indagini geomorfologiche hanno consentito di evidenziare che la dinamica fluviale ha profondamente influito sulle condizioni di stabilità dell’alveo del fortore in tempi storici attraverso una serie di fenomeni di aggradazione e incisione e conseguenti variazioni altimetriche del fondovalle. in particolare, a partire da un livello del fondovalle posto a ca. 3 m dall’attuale, cui si collega la struttura del ponte romano, si ricostruiscono almeno tre episodi di alluvionamento che hanno portato prima al danneggiamento e poi alla distruzione e al seppellimento del ponte romano e della sovrastante struttura medievale. l’innalzamento complessivo del fondovalle dall’epoca repubblicana a quella medievale è stimabile in ca. 6 m. in sintesi, le indagini geofisiche e geomorfologiche hanno dato un valido contributo alla interpretazione del sito archeologico, le prime andando a costituire la base per eventuali scavi futuri od azioni di recupero, le seconde nel caratterizzare il contesto morfologico e morfodinamico in cui si inseriscono le vicende del ponte di tufara. viceversa, il contesto archeologico locale ha dato un contributo importante all’inquadramento cronologico delle fasi morfoevolutive ricostruite e alle considerazioni sulla possibile influenza esercitata da fattori climatici e antropici. abstract: rosskopf et al., integrated geoarchaeological investigations in the central molise (southern italy): the roman bridge of tufara. (it issn 0394-3356, 2007). although the molise region is being discovered to be of exceptional value as to his archaeological and historical heritage, the frame about the spatial-temporal distribution of settlements and related economical-cultural expressions is full of gaps. this circumstance clearly evidences the difficulties to relate archaeological data to the environmental contexts and changes and to investigate the influence of the latter ones on human events. the present paper illustrates one of the first experiences of geoarchaeological investigation in the central molise area region which is based on an integrated approach of archaeological, geophysical and geomorphologic analyses. the structure which has been investigated is localized in the medium-lower valley of the fortore river in locality pesco del ponte, municipality of tufara (southern italy). at this site, remains of a roman bridge were exposed along the left bank of the fortore river after a flood event in january 2003. said remains consist in a pillar of a bridge which can be dated, on the basis of the technique used for the working of the rock blocks, to the republican age (ii-i centuries bc). superimposed on the roman remains are remnants of a brick work with mortar which indicate a remaking of the bridge in medieval times. the discovery of the roman bridge is very interesting as it documents the presence of a road crossing the fortore river just there. as suggested by the analysis of literature and cartographichistorical documents, that road could be one of the two main ones that met within the centre of the ancient saepinum. it gives further evidence of the strategic role the fortore valley played in historical times as the natural connection between the sannium to the west and the daunia to the east. to evaluate the prosecution of the bridge structure in the sub-soil, electric vertical soundings based on the dipolar method have been carried out. these soundings have allowed the restitution of tomographic sections showing the anomalies in resistivity at different depths. the reconstructed anomalies clearly evidence the presence, at a few meters depth, of a structure which can be most probably identified with the prosecution of the bridge. geomorphologic analyses have allowed us to evidence that fluvial dynamics has greatly influenced the stability of the valley bottom in historical times. a number of important variations in height of the valley floor related to alternating phenomena of valley incision and filling could be reconstructed. particularly, beginning from a valley floor level at about – 3 m from the present one, on which the roman bridge was constructed, at least three events of flooding could be reconstructed which first caused the damaging of the bridge and then the destruction and burial of the roman and the superimposed medieval structure cumulating a valley aggradation of about six meters. in synthesis, the geophysical and geomorphologic analyses have contributed in a significant way to the interpretation of the archaeological site, the first approach by giving valid indications about the probable prosecution of the bridge, useful for future excavation, the second one by allowing to detail the morphologic and dynamic contexts which have characterised the fortore valley floor from roman to late medieval times. on the other hand, the archaeological data have given an essential contribution to define the chronological frame of the reconstructed sequence of events, and therefore also to the investigation into the role of human or climatic factors. parole chiave: geoarcheologia, morfologia e dinamica fluviale, fiume fortore, molise, periodo storico. keywords: geoarchaeology, fluvial morphology and dynamics, fortore river, molise, historical period. il quaternario italian journal of quaternary sciences 19(2), 2006 241-252 242 c.m. rosskopf, g. de benedittis & p. mauriello 1. premessa il molise costituisce una regione di straordinaria ricchezza archeologica ancora poco conosciuta. a prescindere, infatti, da una serie di siti archeologici più noti e studiati (es. il sito paleolitico di isernia la pineta (peretto, 1996) e dalle pur numerose segnalazioni di ritrovamenti, purtroppo spesso non meglio documentati, esiste ad oggi un quadro del tutto lacunoso circa la frequentazione del territorio molisano nelle diverse epoche storiche. a ciò è collegata di conseguenza la difficoltà di ricostruire oltre alle singole vicende e forme insediative i contesti e cambiamenti ambientali in cui queste si inseriscono. il presente lavoro illustra una delle prime esperienze di indagine geoarcheologica integrata effettuata nell’area del molise centrale (fig. 1). oggetto dell’indagine sono i resti di un ponte romano la cui segnalazione è dovuta all’associazione culturale locale a’ ficurell di tufara (provincia di campobasso). lo studio effettuato è stato finalizzato sia ad una migliore conoscenza del sito archeologico in esame sia ad un suo inquadramento ambientale. l’area di indagine ricade nella valle del fiume fortore che nel passato ha goduto di grande importanza, avendo rivestito un carattere strategico specie in epoca preromana per essere il naturale collegamento tra il sannio ad ovest e la daunia ad est. ciò mette inoltre in rilievo, come anche documentato dalle scoperte archeologiche finora effettuate, l’importanza che nel passato hanno assunto gli assi fluviali nel favorire gli spostamenti da e verso la costa adriatica. 2. indagini archeologiche nonostante in questi ultimi anni si siano intensificati gli studi sui ponti presenti nel molise (ambrosetti, 1958; monaco, 1989; galliazzo, 1994; marino, 1996; pelosi & sabelli, 1996; caiazza, 1997; matteini chiari, 1997), c’è ancora molto da fare; ne è una riprova il ponte di recente scoperto in agro di tufara sul fiume fortore, in località pesco del ponte (fig. 2), toponimo a cui in precedenza non era collegato nessun elemento strutturale a vista. la sua acquisizione è recente quanto fortunosa: il ponte è stato infatti messo in luce a seguito di un recente evento alluvionale avvenuto nel gennaio 2003, allorché la piena fluviale ha causato l’erosione della sponda sinistra del fiume fortore fino a far emergere parti di esso. le indagini e le rilevazioni svolte hanno consentito l’identificazione dei materiali costruttivi nella pietra calcarea proveniente da cave dell’alta valle del fortore. le caratteristiche del litotipo sono la grana molto fine, una bassa porosità e una buona resistenza meccanica. l’apparecchio esterno del ponte è caratterizzato da fig. 1 ubicazione dell’area studiata (vedi riquadro) e del ponte romano di tufara. il tratto in grigio rappresenta la viabilità romana ipotizzata che collegava la valle del fortore (con il passaggio sul fiume in corrispondenza del ponte di tufara), attraverso i monti del sannio, con l’antico saepinum. su sfondo grigio vengono evidenziate le antiche città romane collegate o no a tale viabilità. location of the study area (framed area) and the roman bridge of tufara. the grey tract represents the hypothetic roman road which connected the fortore valley (crossing the river at the tufara bridge), through the sannium mountains, with the ancient saepinum. the grey backgrounds evidence the ancient roman towns connected or not to said road. 243indagini geoarcheologiche integrate ... conci perfettamente squadrati e ben rifiniti nelle superfici di contatto, mentre nelle superfici a vista presenta la tecnica del bugnato (fig. 3). e’ evidente l’alternanza di elementi lapidei a grande taglia con altri di altezza minore, ma esuberanti in lunghezza. i blocchi si collocano in corsi differenti e, pur essendo perfettamente riquadrati e tagliati nelle superfici di contatto presentano zeppe disposte regolarmente tra le superfici di contatto. nella parte superiore le murature sono caratterizzate da conci di dimensioni variabili, regolari nel taglio ma non nella lavorazione. le sensibili differenze di materiali e di apparecchio utilizzate lasciano pensare a due fasi costruttive cronologicamente successive più che a rimaneggiamenti. il rilievo (fig. 4) e le indagini in situ non solo hanno messo in luce gli aspetti relativi alla fabbrica (materiali utilizzati, tecniche costruttive, sequenze degli interventi di trasformazione), ma anche alcuni processi di degrado presenti sulle superfici a vista del pilastro dovute al dilavamento delle acque fluviali con conseguente corrosione lineare delle superfici (oggi allisciate) lì dove compare il bugnato e dilatazione in alcuni punti degli spazi tra le superfici di contatto. sulla parte alta dove cambia la tecnica muraria caratterizzata da ampio uso di legante, le disgregazioni e le fratture sono molto evidenti; qui manca traccia del paramento originario. e’ visibile solo parte dei due muri d’accompagnamento disposti obliquamente rispetto al muro di testa con cui le murature non trovano soluzione di continuità; il muro di testa presenta una cornice d’imposta continua formata da grossi blocchi con aggetto a gola dritta su cui si sovrappone un ampio listello appena sporgente e con superficie ruvida; la sporgenza non trova continuità nei muri d’ala dove la cornice scompare, ma non il blocco su cui si dispone, che continua anche nel muro d’ala. sulla faccia superiore del muro d’ala di sinistra compare un tratto di blocchi allineati che sembra separarla dalla muratura del muro di testa; ciò lascia presumere una diversa fase costruttiva dei due corpi; i muri d’accompagno che correvano lungo la sponda del fiume sono tuttavia in parte ancora coperti da sedimenti fluviali; ciò non consente una lettura più complefig. 2 stralcio topografico semplificato del tratto di fondovalle studiato (tratto dalla tavoletta i.g.m.i. volturara appula (f. 163, iii no) in scala 1:25.000). topographic simplified sheet of the studied valley floor sector (drawn from i.g.m.i. topographic sheet volturara appula (f. 163, iii no) in scale 1:25.000). fig. 3 il ponte di tufara appena esposto a seguito dell’alluvione del gennaio 2003. la freccia indica un frammento di muratura della struttura medievale. a view of the roman bridge of tufara immediately after the flood event in january 2003. the arrow indicates a fragment of the walling of the medieval bridge structure. 244 ta. il pilone è costruito con grossi conci squadrati e con faccia vista bugnata, tecnica che compare nei ponti romani prevalentemente di epoca tardo-repubblicana (ii-i sec. a.c.); della struttura resta un’ampia cornice d’imposta che separa il pilone dall’arcata, di cui rimane solo qualche traccia; il muro di testa misura 4,4 m, corrispondenti a 15 piedi romani; non è possibile recuperare altre dimensioni utili in quanto buona parte della struttura è coperta dal limo fluviale, ma la posizione della cornice d’imposta lascia presumere che la parete sia molto più alta di quanto emerge dal fondo fluviale (1,5 m compresa la cornice). nel terreno circostante sono stati rinvenuti frammenti di pareti relative a vasi a vernice nera cronologicamente riferibili al ii i sec. a.c. per tipo di argilla e vernice. a breve distanza dall’area del ponte, presso lo sbocco del vallone teverone (fig. 2), durante i lavori agricoli è stata trovata una tomba di epoca ellenistica; del corredo si è salvata una coppa a vernice nera quasi integra, risalente alla fine del iv – inizio iii sec. a.c. sul versante destro del fiume, sulla collina che affaccia sul ponte, è inoltre da ricordare la presenza di una villa romana attestata non solo da ruderi, ma anche da un tesoretto di monete repubblicane rinvenuto alcuni anni or sono (ceglia, 1984). l’area, dunque, appare frequentata in epoca repubblicana, periodo a cui rimanderebbe la tecnica di lavorazione dei blocchi utilizzati per la costruzione del ponte di tufara. il ponte permette di ipotizzare, già in epoca repubblicana, la presenza di una strada di cui non avevamo alcun dato, almeno apparentemente. in effetti, la rilettura della principale fonte cartografica per conoscere la viabilità romana, la tabula peutingeriana (copiata nel xii-xiii secolo ad da un originale del iv secolo d.c., e giunta a noi attraverso varie edizioni fino a quella più moderna di weber (1976) cui si fa riferimento per il presente lavoro), propone una strana descrizione: lì dove compare il toponimo hercul' rani, (segmento vi, 3), c’è anche un castelletto (in genere indicativo di un municipium) in cui viene riconosciuta aecas, città romana corrispondente all'attuale troia. la rappresentazione grafica, considerando che ci troviamo di fronte ad una copia medioevale di un originale romano, potrebbe permetterci di ipotizzare che il copista abbia erroneamente sovrapposto due tratti indicanti due vie romane diverse. la lettura della tabula peutingeriana consente quindi, anche se con la dovuta cautela, di ipotizzare l’esistenza di una strada di cui farebbe parte il nostro ponte romano (fig. 1); considerando che la tabula peutingeriana è datata al iv sec. d.c, è da presumere che il ponte sia stato utilizzato per tutta la fase imperiale. oltre ai dati strutturali, sull’esistenza del ponte in epoca medioevale, sono da ricordare una serie di altre fonti storiche: • tra i documenti conservati nell'archivio di monte cassino (dell’olmo, 2000) ve ne sono tre che si riferiscono a tre diverse donazioni di chiese fatte da nobilone, conte del castello di vipera, i cui resti sopravvivono sulla cima omonima posta tra gambatesa e tufara, paese quest’ultimo (fig. 1) nel cui territorio ricade il nostro ponte. nel primo documento, datato al 1070 (bloch, 1989; dell’olmo, 2000) tra gli elementi utilizzati per individuare i limiti del territorio donato si parla di una via beneventana, denominazione a noi nota, ma riferita ad un altro tratto di strada che, partendo dall'antica città romana di saepinum, portava a benevento (cuozzo & marten, 1998). l'identità di denominazione fa presupporre che in epoca medioevale lungo la valle del torrente tappino (uno dei principali tributari sinistri del fiume fortore, fig. 1) passasse un'arteria viaria che, provenendo da benevento e passando per saepinum, giungesse al fiume fortore. • in un documento del xiii secolo che riguarda jelsi, paese posto a breve distanza da tufara e ubicato nella valle del torrente tappino, si parla ancora di una via publica che passa per la località pantaneto, forse presso la località cantalupo (amelli, 1903). • il percorso sul versante meridionale è denominato via di s. angelo in un testo della metà del xiii secolo (amelli, 1903), denominazione che fa riferimento alla chiesa di s. angelo posta su un rilievo collinare (m. s. angelo, fig. 1) in destra del fortore di fronte al ponte. • sulla via in terra battuta ai margini della quale è la chiesa di s. angelo, in direzione di s. bartolomeo in galdo (fig. 1), c’è un’iscrizione posta su una roccia che si erge a metà percorso denominata pietra cruciata, su cui sono incise le lettere r(egio) b(raccio) s(an) b(artolomeo) su due linee; la forma delle lettere permette di far risalire l’iscrizione a non oltre il xvii secolo e documenta la presenza di un braccio tratturale diversamente a noi sconosciuto. • il ponte di tufara è inoltre ricordato il 30 giugno 1440 quale spettatore di un conflitto tra aragonesi e angioni (di costanzo, 1735; masciotta, 1915). fig. 4 il ponte di tufara: rilievo delle emergenze. a view of the structural features of the tufara bridge. c.m. rosskopf, g. de benedittis & p. mauriello 245 i dati elencati ci consentono di parlare della presenza del ponte ancora in epoca medioevale tra il 1070 ed il 1440; per il periodo successivo non compaiono altre notizie se non il suo ricordo nel toponimo pesco del ponte, conservato da uno spuntone di roccia posto a poca distanza dai ruderi. 3. indagini geofisiche le prospezioni geofisiche nella zona del ponte romano di tufara sono state condotte nell’ambito delle attività del corso di laurea in scienze dei beni culturali ed ambientali dell’università degli studi del molise. l’esigenza era quella di ottenere indicazioni sulla struttura del sottosuolo fino alla profondità di diversi metri. avendo i terreni superficiali dell’area in esame conducibilità elettriche relativamente elevate è stata scartata l’ipotesi di effettuare indagini georadar che non sono in grado di fornire un’adeguata profondità di investigazione. si è quindi scelto di procedere con una serie di prospezioni geoelettriche che, pur essendo in generale meno speditive, hanno una profondità di investigazione notevolmente superiore (mauriello, 2002). il metodo geoelettrico consiste nella determinazione sperimentale della distribuzione di resistività caratterizzante la struttura elettrica del sottosuolo. il principio fisico del metodo è il seguente: una corrente elettrica è inviata nel sottosuolo tramite una coppia di elettrodi (elettrodi energizzanti) e la risultante distribuzione di potenziale elettrico indotto è determinata tramite un’altra coppia di elettrodi (elettrodi riceventi) connessi ad un voltmetro. ogni disomogeneità presente nel sottosuolo, e per disomogeneità s’intendono corpi a diversa capacità di conduzione elettrica, viene rilevata dal fatto che essa deflette le linee di corrente e distorce pertanto la normale distribuzione di potenziale elettrico. in definitiva, misurando la caduta di potenziale su due punti arbitrari, si è in grado di determinare la resistività elettrica del sottosuolo moltiplicando il rapporto tra la caduta di potenziale e la corrente inviata per un coefficiente geometrico dipendente dalla disposizione degli elettrodi sul terreno. variando la posizione del dispositivo elettrodico sull’area da investigare si ottiene la determinazione della distribuzione di resistività nel volume interessato dalla circolazione di corrente elettrica. come già accennato, in generale la prospezione geoelettrica è meno speditiva di quella georadar e magnetometrica ma possiede, oltre ad una maggiore profondità di investigazione, anche un’affidabilità del risultato notevolmente superiore in qualsiasi condizione logistica del terreno. per ovviare al problema della limitata velocità di acquisizione, nella prospezione in esame è stato adoperato un sistema di acquisizione dei dati interamente progettato all’interno dell’università del molise e dell’istituto per le tecnologie applicate ai beni culturali del cnr di roma. il sistema è composto da: 1) un generatore di onde quadre a frequenza di 33hz (in modo da evitare qualunque disturbo dovuto alle linee elettriche e di ottenere tempi di misura rapidissimi); 2) un ricevitore di segnali con integrati un filtro passabanda e una scheda di acquisizione ed elaborazione; 3) un dispositivo di trasmissione tramite radio-modem dei segnali di controllo tra ricevitore e generatore: ciò ha permesso di eliminare qualsiasi tipo di cavo tra le due unità rendendo il sistema di acquisizione estremamente compatto e maneggevole. per ottenere informazioni più rigorose sulle reali ubicazioni delle anomalie riscontrate, i dati sono stati sottoposti ad una procedura di inversione tomografica 3d (mauriello & patella, 1999) con il risultato finale della restituzione di sezioni reali di probabilità di occorrenza di anomalie di resistività nel sottosuolo. queste rappresentano la probabilità che in ogni punto del sottosuolo esista un’anomalia di resistività rispetto al modello di riferimento che genera l’intero set di dati misurati. nelle sezioni orizzontali estratte a varie profondità valori positivi più alti sono relativi a zone con alta probabilità di presenza di anomalie positive di resistività rispetto al modello medio di riferimento, mentre, al contrario, valori negativi sono relativi a zone con alta probabilità di presenza di anomalie negative di resistività. i risultati delle indagini geoelettriche eseguite presso il ponte di tufara sono illustrati in figura 5 dove fig. 5 tomografie di resistività alle profondità di 1, 2 e 3 metri dal piano campagna. tomographic resistivity slices at depths of 1,2 and 3 meters below the topographic surface. indagini geoarcheologiche integrate ... 246 sono riportate tre sezioni orizzontali di probabilità di occorrenza di anomalie di resistività. le zone a più alta resistività, caratterizzate cioè da colori verso il rosso, sono quelle in cui è più alta la probabilità di trovare anomalie rilevanti, correlabili quindi a strutture di attraversamento o a resti di tracciati viari. in conclusione, le sezioni tomografiche, riportate in coordinate chilometriche (sistema gauss-boaga), mostrano chiaramente, soprattutto nella sezione relativa alla profondità di 1 m, la presenza nel sottosuolo di una struttura che va presumibilmente identificata con la prosecuzione del ponte. 4. indagini geomorfologiche le indagini geologico-geomorfologiche sono state estese ad un piccolo tratto del fondovalle attuale del fiume fortore, lungo ca. 3 km, al cui interno si situano ad una quota di 235 m s.l.m. i resti del ponte romano, e alle superfici terrazzate sospese fino ad un massimo di poco più di 20 m sul fondovalle attuale. il tratto di fondovalle in esame è caratterizzato da una morfologia tipicamente piatta, legata alla sua origine aggradazionale. esso presenta una larghezza piuttosto ridotta di ca. 300 m in corrispondenza del ponte romano, per poi allargarsi progressivamente fino a raggiungere ca. 900 m presso la confluenza del torrente teverone, posta 2 km più a valle. lungo i fianchi vallivi affiorano in prevalenza terreni argillosi (vezzani et al., 2004) riferibili rispettivamente alla formazione delle argille del f. fortore di età messiniana ed alle argille scagliose (cretacico superiore miocene inferiore). quest’ultime, ben note in letteratura come argille varicolori (melidoro, 1971), sono riportate con la sigla av nel foglio n. 162 della carta geologica d’italia. subordinatamente sono presenti, inoltre, terreni a prevalente componente sabbioso-arenacea riferibili alla formazione delle sabbie di valli (vezzani et al., 2004), mentre terreni calcarei affiorano soltanto nelle porzioni alte del bacino del fortore. i depositi quaternari affioranti nell’area di studio sono costituiti in prevalenza da depositi fluviali, e localmente da depositi colluviali e cumuli di frana. i primi sono presenti sia nell’area del fondovalle attuale, sia in corrispondenza delle superfici terrazzate (vedi oltre) presenti ai suoi lati, e sono rappresentati da ghiaie, generalmente di dimensioni da centimetriche a decimetriche, sabbie e limi. lungo i bordi del fondovalle attuale si rinvengono dei cumuli di frana derivanti da fenomeni semplici (scivolamenti e colamenti) o complessi (soprattutto del tipo scivolamento-colata) che hanno interessato in prevalenza la formazione delle argille scagliose. una visione molto schematica, prospettica, della morfologia del tratto vallivo in esame è illustrata in figura 6 che mette in evidenza le posizioni occupate dall’alveo e dalla piana alluvionale del fortore in vari momenti della sua evoluzione più recente, evidenziate da diversi ordini di superfici terrazzate (i, ii, vi, vii e viii) poste a varie quote sull’alveo attuale del fiume (ix). nell’area di studio non si rinvengono lembi di terrazzi fluviali sospesi oltre 5 m sulla quota del fondovalle attuale, ma soltanto lembi di corpi di conoide. ciò probabilmente è dovuto, da un lato, alla elevata instabilità dei fianchi vallivi, impostati in prevalenza su terreni argillosi, e alla conseguente diffusa presenza di fenomeni franosi anche di grandi estensioni, e dall’altro anche alla durata piuttosto limitata delle soste del fiume a determinate quote nel corso dell’approfondimento dell’incisione valliva. le superfici terrazzate rinvenute a quote più elevate (per semplificazione indicate come un unico ordine i in figura 6), sospese tra 22 m e 10 m sul livello dell’alveo attuale, costituiscono i resti di diverse generazioni di conoidi. in particolare, allo sbocco del vallone teverone si riconoscono almeno due generazioni, tra loro incastrate. queste conoidi evidenziano importanti fasi di deposizione detritica agli sbocchi dei principali valloni tributari (valloni teverone e canneto) presenti nel tratto di fondovalle in esame, che hanno temporaneamente bilanciato la prevalente tendenza all’incisione del fiume fortore e il conseguente progressivo abbassamento del livello del fondovalle. la loro genesi appare collegabile, in prima ipotesi, considerato anche l’entità del successivo approfondimento del fondovalle, e in analogia a quanto documentato da vari studi per l’italia centro-meridionale, a fasi di deterioramento climatico che hanno caratterizzato il pleistocene superiore in generale e l’ultimo massimo glaciale (lgm, orombelli et al., 2005) in particolare (basso et al., 1996; cinque et al., 1997; coltorti, 1997; scarciglia et al., 2003). allo sbocco del vallone teverone sono stati rilevati (località ischia dei molini, fig. 2), ancora altri lembi di conoide, frontalmente troncati e terrazzati tra 5 e 10 m sul livello dell’alveo, riferibili ad almeno due ordini. queste conoidi sembrano correlarsi a fasi morfoevolutive molto più recenti, ma la frammentarietà delle evidenze morfologiche non permette di proporre delle correlazioni con i terrazzi alluvionali discussi qui di seguito. in base alla sequenza degli eventi ricostruita, il fondovalle, in un periodo non ben inquadrabile cronologicamente, ma certamente pre-classico (vedi oltre), si era già stabilizzato ad una quota di ca. 5 m sull’alveo attuale (superficie terrazzata di ii ordine, presso masseria colella, figure 6 e 7). tuttavia, non è possibile stabilire, se questa sua posizione altimetrica fosse semplicemente il risultato di una fase di stasi dell’approfonfig. 6 rappresentazione schematica della morfologia del fondovalle del fortore nell’area di studio. i, ii, vi, vii, viii: vari ordini di superfici di origine fluviale; ix: l’alveo attuale; 1*: masseria colella. schematic representation of the fortore valley floor morphology in the study area. i, ii, vi, vii, viii: different orders of alluvial surfaces; ix: present river bed; 1*: masseria colella. c.m. rosskopf, g. de benedittis & p. mauriello fig. 8 car a t t e r i s t i c h e delle successioni fluviali riferibili ai livelli iv-vi affioranti lungo la sponda sinistra del fiume fortore nel tratto a monte del ponte. la linea t r a t t e g g i a t a segna l’orlo superiore della piccola scarpata che separa le superfici terrazzate di ii e vi ordine. features of the fluvial sequences related to levels iv-vi outcropping along the left bank of the fortore river upstream of the bridge. the dashed line shows the upper edge of the little scarp separating the terrace surfaces of ii and vi order. dimento progressivo del fondovalle, o invece frutto di una temporanea tendenza all’aggradazione. di certo, il fatto che il terrazzo di masseria colella risulti impostato su una successione di ghiaie con clasti poligenici da sub-arrotondati a ben arrotondati e di dimensioni piuttosto omogenee (prevalentemente tra 10 e 20 cm di diametro), immersi in matrice sabbioso-limosa, consente di escludere fenomeni di aggradazione del tutto locali, come quelli causati da fenomeni di sbarramento della valle per frana. in un momento successivo avviene una ripresa della tendenza all’incisione del fondovalle, che porta ad una cambiamento significativo della sua morfologia ed alla situazione topografica in cui trova collocazione la struttura del ponte romano. questa fase di incisione (ed eventuale successivo alluvionamento?) porta l’alveo a stabilirsi, prima del ii secolo a.c., ad una quota di almeno 3 m rispetto al suo livello attuale (superficie di iii ordine, fig. 7), causando il terrazzamento della superficie di ii ordine. questa fase di terrazzamento, come testimonia il ritrovamento sul terrazzo di masseria colella di resti di ceramica riferibile a fine iv – inizio iii secolo a.c., è databile almeno all’inizio dell’epoca ellenistica. dopo la costruzione del ponte romano il fondovalle del fortore è interessato da una fase di aggradazione che causa l’innalzamento dell’alveo di ca. 3 m (superficie di iv ordine, figure 7 e 8) e il danneggiamento del ponte che viene parzialmente seppellito da un deposito ghiaioso, costituito da clasti poligenici di dimensioni generalmente entro il decimetro immersi in matrice sabbioso-limosa, che chiude verso l’alto con uno strato spesso pochi decimetri di limo argilloso debolmente pedogenizzato (fig. 9). questa fase di aggradazione, in base ai dati archeologici precedentemente esposti, è inquadrabile nella seconda metà del i millennio d.c. il ponte, dopo il suo rifacimento in epoca medioevale intorno all’anno mille, come testimoniato dalla tecnica di costruzione impiegata e dalle più antiche citazioni in letteratura, è soggetto ad almeno due episodi alluvionali, ben documentati dai depositi ghiaioso-sabbiosi e limosi esposti lungo la sponda sinistra intorno al 247 fig. 7 profilo trasversale schematico del fondovalle del fiume fortore all’altezza del ponte romano. a) i: superfici di conoide di i ordine; ii-viii: livelli occupati dal fiume nel corso della sua evoluzione storica; ix: livello dell’attuale alveo. b) schema di dettaglio della sponda sinistra che evidenzia i vari livelli occupati dal fiume e il loro rapporto con la struttura del ponte romano. schematic cross profile of the fortore valley floor at the height of the roman bridge. a) i: first order alluvial fan surfaces; ii-viii: successive levels occupied by the river bed during his historical evolution; ix: level of the present river bed. b) detailed scheme of the left river bank showing the different levels occupied by the river and their relation to the structure of the roman bridge. indagini geoarcheologiche integrate ... sito archeologico (figure 8 e 9). in seguito al primo episodio il letto del fiume si innalza fino a raggiungere la struttura medioevale (superficie di v ordine, figure 7 e 8). in seguito ad una seconda fase di alluvionamento durante la quale l’alveo si porta a ca. 2/2,5 m sul suo livello attuale (superficie di vi ordine, figure 7 e 8), avviene la definitiva distruzione – si nota a riguardo la presenza subito a monte del ponte di un grosso frammento di muratura che si appoggia sulla superficie di v ordine (figure 3 e 7b) e il seppellimento del ponte. la superficie di vi ordine rimane separata morfologicamente da quella di ii ordine da una piccola scarpata lineare, alta ca. 1 m, che si segue anche lateralmente per ca. 300 m (fig. 8). questo secondo episodio alluvionale, responsabile della definitiva interruzione della viabilità, può essere inquadrato tra il 1440 e il 1700 ad, in base alle citate fonti letterarie che fanno menzione del ponte e al rinvenimento di frammenti ceramici di epoca rinascimentale sulla superficie di vi ordine. entrambi gli episodi di alluvionamento appena descritti sono quindi inquadrabili tra il 1440 e il 1700 ad ed hanno comportato nell’insieme un importante innalzamento di ca. 3 m del fondovalle. circa l’evoluzione più recente del fondovalle è possibile evidenziare un leggero abbassamento, avvenuto in più fasi, dell’alveo fluviale (figure 6 e 7a), testimoniato dai livelli vii, viii (rappresentanti rispettivamente la piana alluvionale e l’alveo del 1954) e dal livello ix (l’alveo attuale). attualmente, il fondovalle si presenta sostanzialmente stabile, come evidenzia l’abbassamento molto modesto (di solo 1 m) avvenuto durante gli ultimi 50 anni. tale stabilità è probabilmente imputabile alla presenza dell’invaso artificiale di occhito, posto pochi chilometri più a valle del tratto vallivo studiato, che ha garantito un livello di erosione costante, modulando ed inibendo negli ultimi decenni una possibile tendenza più pronunciata all’incisione del fondovalle. 5. discussione e considerazioni conclusive i dati esposti mostrano che le vicende del ponte di tufara e della collegata viabilità in epoca romana e medioevale si inquadrano in una dinamica ambientale piuttosto complessa. le indagini geomorfologiche, infatti, hanno messo in evidenza che a causa della dinamica fluviale si sono avuti ripetuti spostamenti laterali e variazioni altimetriche dell’alveo del fiume fortore, con un innalzamento di complessivi 6 m circa dall’epoca romana a quella medievale. le variazioni plano-altimetriche registrate, imputabili a fenomeni alternati di aggradazione e di incisione fluviale, non solo hanno portato a cambiamenti talora radicali nella fisionomia del fondovalle, ma soprattutto hanno variamente condizionato la percorribilità e la stabilità delle vie di attraversamento fluviale in generale e del ponte di tufara in particolare. circa il ruolo dei fattori climatici e/o antropici nel determinare le riscontrate variazioni altimetriche del fondovalle, lo studio condotto, anche per il suo carattere locale, non consente di giungere a conclusioni definitive. tenendo conto della localizzazione dell’area di studio e del periodo indagato, è possibile escludere una diretta influenza di eventuali variazioni glacio-eustatiche tardo-oloceniche del livello del mare sulla tendenza all’aggradazione o incisione del corso d’acqua. appare perciò lecito porre suddette variazioni innanzitutto in relazione a minori o maggiori apporti detritici all’alveo e/o portate liquide del fortore, che hanno influito sulla capacità di trasporto e di erosione del fiume. riesaminando nell’insieme i dati acquisiti, è possibile individuare varie fasi di instabilità del fondovalle del fortore nel periodo storico, determinate alternativamente dalla sua tendenza prevalente all’approfondimento o all’aggradazione. sinteticamente, le fasi evolutive distinte fanno riferimento ai seguenti periodi, che in base ai dati cronologici disponibili sono ovviamente da considerarsi solo di prima approssimazione: fasi di approfondimento: pre-ii secolo a.c.; 1700 (1900?) ad attuale; fasi di aggradazione: seconda metà del i millennio d.c.; post-1440 1700 (1900?) ad; fasi di sostanziale stabilità : ii secolo a.c. – iv/v? secolo d.c.; 1070 1440 ad. la costruzione del ponte romano avviene in un periodo di sostanziale stabilità morfologica del fondovalle che sembra essere perdurato per tutto il periodo tardo-repubblicano (ii-i secolo a.c.) e quello imperiale (i – iv/v? secolo d.c.), e che era presumibilmente collegato solo inizialmente a condizioni climatiche più fredde e/o umide rispetto ad oggi (röthlisberger 1986; furrer et al., 1987; giraudi, 2002). tra le fasi evolutive distinte, quelle di aggradazione meritano una particolare attenzione, perché hanno direttamente influito sulle vicende del ponte di tufara. la prima fase di aggradazione, riferibile alla seconda metà del primo millennio d.c. (500-1000 ad), evidenza condizioni di elevata instabilità morfologica simili a quelle che hanno determinato, nello stesso intervallo di tempo e in aree molto vicine a quella studiata, l’avanzamento del delta del fortore (“seconda fase di delta a cuspide”, gravina et al., 2005) e la fase di aggradazione nella valle del torrente cigno, affluente del fiume biferno, documentata da barker (1995) e datata all’inizio del medioevo (720 ad). questa prima fase di aggradazione si inquadra in un periodo di chiara recrude248 fig. 9 dettaglio della sponda sinistra relativo al riquadro nella figura precedente. detail of the left bank showing the framed area indicated in the previous figure. c.m. rosskopf, g. de benedittis & p. mauriello scenza climatica come indicano soprattutto i dati pollinici, climatici e quelli sugli avanzamenti dei ghiacciai riferiti alle aree alpine europee (orombelli & porter, 1982; röthlisberger, 1986; furrer et al., 1987; grove, 1988; baroni, 2000; cremaschi, 2000, holzhauser et al., 2005), ma anche quelli, per citarne alcuni, sull’innalzamento di livello di alcuni laghi appenninici (giraudi, 2000; 2004) e sull’avanzamento del ghiacciaio del calderone (giraudi, 2002). in ambito mediterraneo questa fase evolutiva si collegherebbe ad un periodo distinto da importanti e talora rapidi fenomeni di alluvionamento. secondo alcuni autori (vita-finzi, 1969; veggiani, 1983; ortolani & pagliuca, 1994; giano & guarino, 1996) questi fenomeni di alluvionamento sarebbero legati a condizioni climatiche più freddo-umide delle attuali, secondo altri (br ü c k n e r, 1983; ab b o t t & valastro, 1995; barker, 1995; barker & hunt, 1995; coltorti, 1997), invece, gli stessi sarebbero più che altro il risultato di interventi antropici sulle coperture del suolo e, in particolare, di azioni di disboscamento in epoca romana. i numerosi dati climatici a disposizione, tuttavia, suggeriscono almeno una concomitanza tra cause antropiche e climatiche, se non addirittura il prevalere del controllo climatico. sotto una forte influenza climatica si è svolta presumibilmente anche la seconda fase di aggradazione, collocata nel periodo tra il 1440 e 1700 a.d. essa, infatti, va a collegarsi ad un periodo caratterizzato da importanti fasi di recrudescenza climatica, conosciuto come la piccola età glaciale (little ice age = lia), inquadrabile approssimativamente, in ambito alpino ed appenninico, tra il 1400/1500 e 1850 (röthlisberger, 1986; f u r r e r et al., 1987; g r o v e , 1988; b a r o n i , 2000; borsato et al., 2003; strumia, 2005). secondo lo studio recente di matthews & briffa (2005), l’inquadramento cronologico della piccola età glaciale andrebbe esteso, sulla base dell’allora estensione dei ghiacciai nelle alpi europee, al periodo 1300-1950 ad. a sostegno dell’influenza climatica globale anche sull’equilibrio dei sistemi fluviali si evidenziano (marabini, 2000) gli andamenti simili delle portate dei maggiori fiumi d’europa negli stessi periodi, e la relazione diretta tra variazioni di portata dei corsi d’acqua e pulsazioni climatiche freddo-umide che hanno distinto la piccola età glaciale, portando ad un aumento degli apporti solidi alle foci a all’avanzamento progressivo della costa dell’alto adriatico tra il 1600 e il 1820. vistosi effetti dell’instabilità morfologica che caratterizza la piccola età glaciale si manifestano anche sulla costa molisana e pugliese, dove si registrano importanti apporti detritici da parte dei corsi d’acqua alle foci fluviali ed agli specchi d’acqua costieri. questi apporti detritici causano, tra gli inizi del 1600 e del 1800, una importante progradazione della linea di costa, documentata dall’avanzamento del delta del fortore (“quarta fase di delta a cuspide”, gravina et al., 2005), dall’accrescimento del cordone sabbioso del lago di lesina (gravina et al., 2005) e dalla formazione di stagni costieri nell’area di foce del fiume biferno (magini, 1620). l’esame della cartografia storica (cartografia topografica in scala 1:50.000 i.g.m.i., edizioni 1869/75 e 1906/09) e dei dati da letteratura (aucelli & rosskopf, 2000; aucelli et al., 2004) evidenzia un persistere della tendenza prevalente alla progradazione della costa molisana almeno fino all’inizio del 1900 e di maggiorati apporti detritici alle foci dei fiumi trigno e biferno che sviluppano una caratteristica morfologia di delta a cuspide. importanti fenomeni di alluvionamento nella bassa valle del fiume trigno si registrano ancora tra il 1845 e il 1850 (aucelli & rosskopf, 2000). ciò consente di estendere questo periodo di crisi climatica almeno fino all’inizio del 1900 per il versante adriatico molisano. in sintesi, le indagini geofisiche e geomorfologiche, effettuate sostanzialmente a sostegno dello studio archeologico, hanno dato un valido contributo alla interpretazione del sito archeologico. l’indagine geofisica, in particolare, ha consentito di effettuare una prima previsione circa la possibile prosecuzione della struttura del ponte, e di avere una base conoscitiva per eventuali futuri scavi od interventi di recupero. le indagini geomorfologiche hanno permesso di caratterizzare il contesto morfologico e morfodinamico in cui il ponte e le sue vicende evolutive si inseriscono. d’altro canto, i dati archeologici provenienti dal sito indagato e dalle aree limitrofe hanno fornito un contributo significativo alla ricostruzione delle locali vicende geomorfologiche in epoca storica e della possibile influenza di fattori climatici e antropici. ringraziamenti si ringraziano il dr. enrico di pasquale e antonio grosso, presidente e vicepresidente dell’associazione a’ ficurell di tufara, ai quali è dovuta la segnalazione del ponte, per la gentile ospitalità e il supporto alle indagini in campo. gli autori desiderano inoltre ringraziare i referees per le indicazioni e consigli utili nella revisione del testo. bibliografia abbott j.t. & valastro s. 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(1983) degrado ambientale e dissesti idrogeologici indotti dal deterioramento climatico nell’alto medioevo in italia. i casi riminesi studi romagnoli, 34, pp. 123-146. vita-finzi c. (1969) the mediterranean valleys: geological changes in historical times cambridge, university press. vezzani l., ghisetti f. & festa a. (2004) carta geologica del molise (alla scala 1:100.000) ed. s.el.ca., firenze. weber e. (1976) (a cura di) tabula peutingeriana. codex vindobonensis 324 graz. 251 ms. ricevuto il 20 febbraio 2006 testo definitivo ricevuto il 31 ottobre 2006 ms. received: february 20, 2006 final text received: october 31, 2006 indagini geoarcheologiche integrate ... imp.montana& definizione composizionale delle “argille ceramiche” presenti nella sicilia nord-occidentale: inquadramento geologico e ricadute di carattere archeometrico g. montana 1, a. caruso 2, a.t. lavore 1, a.m. polito 1 & a. sulli 2 1 dipartimento di chimica e fisica della terra (c.f.t.a.) – università degli studi di palermo (gmontana@unipa.it) 2 dipartimento di geologia e geodesia università degli studi di palermo riassunto: g. montana, a. caruso, a.t. lavore, a.m. polito & a. sulli, definizione composizionale delle “argille ceramiche” presenti nella sicilia nord-occidentale: inquadramento geologoco e ricadute di carattere archetettonico. (it issn 0394-3356, 2007). il presente studio intende fornire un primo contributo alla caratterizzazione composizionale e tecnologica dei depositi argillosi ubicati nella sicilia nord-occidentale, riferibili a ben precise unità stratigrafiche, per i quali è stato dimostrato, o è stato quantomeno ipotizzato, lo sfruttamento, nei secoli passati, come materia prima da impiegare nel processo di manifattura ceramica. pertanto, le argille studiate sono state selezionate sulla base di evidenze geologiche, ma, al tempo stesso, anche archeologiche e etnografiche, ponendo un’attenzione maggiore su quei materiali che, anche grazie alle loro qualità specifiche, siano stati maggiormente apprezzati ed utilizzati nella tradizione ceramica locale. la caratterizzazione composizionale delle argille oggetto di studio è stata fatta con l’obiettivo di iniziare a costruire una banca dati che possa essere in un futuro prossimo funzionale e decisiva per l’identificazione dei cosiddetti “gruppi di riferimento” nei più importanti contesti archeologici presenti nell’area studiata, per cui è stata dimostrata (ritrovamento di fornaci e altre strutture connesse alla manifattura), ovvero ipotizzata la localizzazione di un centro produttivo. un certo numero di campioni rappresentativi (46) è stato prelevato dalle quattro formazioni contenenti argille, che affiorano nella sicilia nord-occidentale considerabili almeno potenzialmente idonee alla manifattura ceramica,: 1) argille di ficarazzi (pleistocene); 2) formazione terravecchia (miocene superiore); 3) flysch numidico (oligocene superiore miocene inferiore) 4) argille varicolori (cretaceo superiore oligocene inferiore). innanzitutto i sopraccitati materiali sono stati attentamente descritti dal punto di vista geologico e biostratigrafico, quindi sono state determinate, discusse e confrontate le caratteristiche tessiturali (distribuzione granulometrica), mineralogiche (analisi per diffrattometria a raggi x) e chimiche (analisi per fluorescenza a raggi x). inoltre, per due tipologie di materiale, per cui è già stato dimostrato l’utilizzo ceramico in importanti casi di studio di interesse archeologico e storico (argille di ficarazzi e formazione terravecchia), è stato simulato in laboratorio un ciclo produttivo completo (impasto e cottura). questo con l’obiettivo di determinare parametri specifici come il comportamento plastico, ritiro lineare e colore in seguito ad essiccamento e cottura, caratteristiche tessiturali e composizionali rilevabili dall’esame di sezioni sottili al microscopio polarizzatore. tutti questi parametri possono, infatti, essere utilizzati per ricostruire il livello tecnico degli antichi cicli produttivi (eventuali trattamenti preliminari, procedure di lavorazione e condizioni di cottura) e per la determinazione di provenienza di reperti di dubbia attribuzione. infine, con l’intento di avere una prima verifica di questo approccio, è stato effettuato un confronto petrografico e chimico tra le argille mioceniche e pleistoceniche, ossia le presunte materie prime, ed alcune classi di manufatti ceramici prodotti localmente in varie epoche, dall’età arcaica a quella classico ellenistica e persino nel periodo barocco. i risultati ottenuti sono accettabili ed incoraggiano il proseguimento della ricerca. abstract: g. montana, a. caruso, a.t. lavore, a.m. polito & a. sulli, geological background and compositional characterization of “ceramic clay” from north-western sicily: archaeometric feed-back. (it issn 0394-3356, 2007). this paper deals with the compositional and technological characterization of clayey materials, belonging to specific stratigraphic units, which are suspected to have been exploited (in the past centuries) for the traditional ceramic manufacture in north-western sicily. the studied clays were selected on the basis of geological, archaeological and ethnographic evidences testifying, in several cases, a longestablished use for local ceramic manufacture. the compositional characterization of raw clays has been used to start off a date base which should be functional for the identification of “reference groups” in several archaeological contexts localized in the studied area which are considered to be production centres. a number of representative samples (46) was collected from different clayey formations cropping out in north-western sicily: 1) ficarazzi clays (pleistocene); 2) terravecchia formation (upper miocene); 3) flysch numidico (upper oligocene lower miocene) 4) argille varicolori (upper cretaceous lower oligocene). in a first phase, these materials were carefully described from a geological and stratigraphic point of view. after that, textural (grain size distribution), mineralogical (xrd) and chemical (xrf) characteristics of the clay samples were carried out and discussed. experimental mouldings and firings on two selected clay types from the above mentioned units, already documented to have been used as raw materials in several archaeological and historical important case studies, were also performed. this has been made in order to simulate a production cycle and to recognize some specific parameters such as plastic behaviour, linear shrinkage, colour and petrographical appearance in thin section under the polarizing microscope. these parameters can be directly used to infer ancient manufacture techniques and firing conditions as well as for provenance determination of doubtful attributed archaeological artefact. for testing out this approach an exemplificative compositional comparison between the miocene and pleistocene clays (the believed raw materials) and some ceramic class locally produced during archaic and classichellenistic age or even in baroque period has been made. acceptable results have been obtained which encourage us to pursue this research. parole chiave: sicilia, materie prime argillose, produzione ceramica, archeometria. keywords: sicily, clayey raw materials, ceramic production, archaeometry, foraminifera. il quaternario italian journal of quaternary sciences 19(2), 2006 279-298 280 g. montana et al. 1. obiettivi ed approccio metodologico la predisposizione geologica della sicilia, molto ricca di terreni argillosi, ha certamente contribuito sin dalla più remota antichità allo sviluppo di una ben radicata tradizione ceramica; attività, questa, che risulta comprovata dal ritrovamento, in buona parte dei siti archeologici dell’isola, di importanti strutture produttive rappresentate da fornaci, vasche di decantazione, accumuli di materia prima, scarti di lavorazione. lo sviluppo della ricerca archeometrica in questi ultimi anni ha posto in chiara evidenza che lo studio petrografico e chimico dei materiali ceramici rinvenuti in un dato contesto territoriale può contribuire in modo determinante ad attestare con attendibilità le produzioni locali, distinguendole dalle importazioni e, conseguentemente, consentire di localizzare le vie di circolazione dei reperti ricavando notevoli ricadute in ambito archeologico ed, in particolare, nella ricostruzione storica e socio-economica delle antiche comunità (hughes, m.j., 1981; peacock, 1982; fulford & peacock, 1984; rice, 1987; lindahl & stilborg, 1995; stark et al., 2000). ancora più recentemente si è incominciata a sviluppare una linea di ricerca che intende affiancare alle analisi dei reperti ceramici la caratterizzazione completa delle materie prime argillose presenti nello stesso territorio (kilikoglou et al., 2002; alaimo & montana 2003). si ritiene infatti che il confronto tra manufatti ceramici e potenziali materie prime possa contribuire non poco a ricostruire con maggiore oggettività il livello tecnologico raggiunto dagli antichi cicli produttivi (eventuali trattamenti preliminari, procedure di lavorazione e condizioni di cottura), oltre a consentire e/o semplificare la determinazione di provenienza di reperti di dubbia attribuzione e la circolazione dei manufatti in contesti territoriali relativamente circoscritti in dati orizzonti cronologici. il presente studio si propone, innanzitutto, di definire preliminarmente le caratteristiche tessiturali e composizionali delle argille che affiorano nella sicilia nordoccidentale, di potenziale interesse ai fini della produzione ceramica antica. tali argille, in primo luogo, sono inquadrate litostratigraficamente e caratterizzate dal punto di vista biostratigrafico, per lo più utilizzando dati di letteratura, al fine di un eventuale futuro confronto con il contenuto fossilifero dei reperti ceramici. in particolare, la ricerca intrapresa intende conseguire i seguenti obiettivi a breve e a medio termine: 1) avviare l’acquisizione di dati che siano funzionali alla realizzazione di una vera e propria banca dati delle “argille ceramiche” locali, che possa consentire di definire gli aspetti tecnologici connessi all’attività di manifattura ceramica, differenziati per classe tipologica, destinazione d’uso dell’oggetto e per contesto cronologico. 2) attestare i centri di manifattura nel territorio oggetto di studio (sicilia nord-occidentale) ed individuare dei criteri oggettivi per distinguere i prodotti locali dalle importazioni attraverso il confronto tra le “potenziali” materie prime argillose e le varie classi di reperti ceramici provenienti da scavi archeologici o anche da complessi architettonici di interesse storico-artistico relativamente più recenti. l’approccio metodologico e le tecniche analitiche utilizzate in questo studio si avvalgono dell’approccio teorico e delle conoscenze sperimentali recentemente maturate nell’ambito di un vasto progetto internazionale1, finalizzato allo studio archeometrico di determinate classi di ceramica archeologica e di alcune materie prime argillose utilizzate per la produzione in ambito mediterraneo (italia, spagna, grecia). le materie prime da analizzare sono state individuate sulla base di accurate indagini preliminari sia a carattere prettamente geologico che di tipo etnografico (attraverso acquisizione di dati sul processo produttivo ceramico così come avveniva nei secoli passati) effettuate capillarmente nel territorio oggetto di interesse, considerando, al tempo stesso, la loro importanza ai fini degli studi archeologici ed archeometrici (attraverso la consultazione dei dati inerenti alle aree con maggiore densità di siti archeologici così come riportate nelle “linee guida del piano territoriale paesistico regionale” edite dalla regione siciliana nel 1999). i campioni rappresentativi delle formazioni argillose individuate sono stati prelevati in affioramento o, più raramente, da fronti di cava. si è avuto cura di effettuare i prelievi quanto più possibile in prossimità degli antichi insediamenti ove si suppone che le stesse argille siano state impiegate, ovvero ad una distanza da essi ragionevole, tenendo in considerazione le difficoltà oggettive che aveva il trasporto di tali materiali nei secoli passati. inoltre, la raccolta dei campioni è stata pianificata per cercare di mettere in evidenza eventuali markers composizionali tra formazioni affioranti nella stessa area ed anche la variabilità nell’ambito di una stessa formazione argillosa tra base e tetto dell’affioramento o in aree tra loro distanti (da pochi chilometri ad alcune decine). i markers composizionali sono rappresentati dai minerali e dai frammenti litici che caratterizzano la componente sabbiosa di ogni singola formazione argillosa, la cui natura ed abbondanza relativa si determina, fondamentalmente, mediante l’esame petrografico in sezione sottile di provini sperimentali cotti a varie temperature. chiaramente, anche la composizione chimica “bulk”, che, in genere, rispecchia molto fedelmente l’abbondanza relativa e la composizione mineralogica della frazione sabbiosa, fornisce criteri distintivi molto efficaci i quali, tuttavia, per una corretta interpretazione, spesso necessitano di una calibratura con i dati minero-petrografici. inoltre, un supporto complementare assai importante (a volte decisivo) alla ricerca di caratteristiche distintive tra materie prime o tra manufatti ceramici con esse realizzati può essere ottenuto mediante la definizione accurata della microfauna calcarea (foraminiferi), specie in aree produttive dove si poteva attingere a più materie prime, poco differenziabili per via petro-chimica. infatti, non così raramente come si potrebbe pensare, specie nei manufatti ceramici di grosse dimensioni (come ad esempio le anfore da trasporto), si trovano parti in cui la temperatura raggiunta 1geopro european tmr network 1998-2001 (erbfmrxct980165) “integrating geochemical and mineralogical techniques: a new approach to raw materials and archaeological ceramic provenance” (coordinator: university of sheffield uk; other partecipants: national centre for scientific research “demokritos” gr, rheinische friedrich wilhelms universität bonn de, universitat de barcelona es, università degli studi di palermo it, the notthingam trent university uk). e/o particolari condizioni di cottura hanno preservato in tutto o in parte i foraminiferi, che, pertanto, individuati nelle osservazioni in sezione sottile o al sem, consentono il più delle volte di circoscrivere cronostratigraficamente l’argilla usata quale materia prima (quinn et al., 1998; 1999 a; 1999 b). 2. campionamento e tecniche di analisi sulla base dei criteri sopra descritti sono stati prelevati 46 campioni di argilla, ritenuti rappresentativi delle materie prime argillose affioranti nella sicilia nordoccidentale, potenzialmente utilizzate per la manifattura ceramica a partire dalla preistoria sino al secolo scorso. questi campioni sono riconducibili a quattro formazioni: argille di ficarazzi (pleistocene inferioremedio), argille della formazione terravecchia (tortoniano superiore-messiniano inferiore), argille del flysch numidico (oligocene superiore-langhiano) e argille varicolori (cretaceo-oligocene inferiore). le argille campionate sono state tutte confrontate in termini di distribuzione granulometrica, di composizione mineralogica e composizione chimica. inoltre, limitatamente alle argille mioceniche (formazione terravecchia) e a quelle pleistoceniche (argille di ficarazzi), che si ritiene abbiano avuto un utilizzo più rilevante in termini sia qualitativi che quantitativi, è stato simulato in laboratorio un ciclo completo di lavorazione artigianale. negli impasti sperimentali sono state determinate alcune caratteristiche tecnologiche (plasticità, ritiro lineare, colore) prima e dopo i cicli di cottura effettuati in atmosfera ossidante ed a varie temperature. inoltre sono state definite anche le caratteristiche petrografiche desunte dall’esame al microscopio polarizzatore delle sezioni sottili dei provini cotti a 300 ed a 950°c, al fine di rendere il confronto maggiormente sistematico ed omogeneo. oltre la metà delle argille analizzate appartiene alla formazione terravecchia (27 campioni). questa scelta è stata indotta dall’estensione degli affioramenti di questa formazione nell’area in esame e, soprattutto, dalle numerose testimonianze ricavate dalla ricerca etnografica circa l’uso secolare che è stato fatto di queste argille nella manifattura ceramica locale (soprattutto nell’area compresa tra termini imerese e collesano da cui proviene il maggior numero di campioni). di contro, i campioni rappresentativi delle argille di ficarazzi sono in numero decisamente inferiore (4). questa limitatezza nei prelievi è dipesa dalla odierna oggettiva rarità degli affioramenti. infatti, gli affioramenti il cui sfruttamento nei secoli passati è ampiamente documentato (cipolla, 1931) sono stati totalmente assorbiti dalla incontrollata espansione edilizia di palermo e dei piccoli centri abitati limitrofi avvenuta nell’ultimo trentennio. anche il numero dei campioni prelevati dal flysch numidico (8) e dalle argille varicolori (7) è più basso rispetto alla formazione terravecchia, tuttavia, in questo caso, la scelta di limitare momentaneamente i prelievi è stata fatta intenzionalmente. infatti, per questi materiali non è stato ancora dimostrato, nel territorio in oggetto, un utilizzo per la produzione di forme vascolari e/o altri manufatti di qualità medio-alta; semmai, al contrario, un impiego sporadico per la manifattura di laterizi comuni (mattoni da costruzione). pertanto sono da considerare di rilevanza 281definizione composizionale delle “argille ceramiche” ... minore in termini di ricaduta storico-artistica e pressoché nulla in termini di ricaduta archeologica. l’analisi granulometrica dei materiali argillosi è stata realizzata per via umida applicando la legge di stokes, dopo averli essiccati (a temperatura ambiente), quartati e decoesionati. essa ha permesso di ottenere, per ogni campione, la percentuale in peso delle frazioni dimensionali principali: sabbia (2÷0.06 mm), silt (0.06÷0.002 mm) ed argilla (granuli con diametro inferiore a 0.002 mm). la composizione mineralogica è stata indagata attraverso analisi per diffrattometria a raggi x (xrd) mediante un diffrattometro philips x’pert. le riprese diffrattometriche sul campione totale sono state effettuate su preparati, preventivamente essiccati e macinati in un mortaio di agata, disorientati per caricamento laterale. sono state applicate le seguenti condizioni operative: intervallo angolare 2°÷60° 2θ; velocità del goniometro 2° 2θ /min (step size 0.020; time per step 0.50; scan speed 0.04; detector reference slit 0.2 mm); radiazione cukα (40 kv, 40 ma), monocromatore a grafite. le stime di abbondanza relativa delle fasi mineralogiche individuate sono state effettuate in base all’intensità dei picchi, a loro volta determinate in base alle aree dei riflessi specifici e moltiplicate per i relativi fattori di correzione, in accordo a laviano (1987). il riconoscimento e la stima semiquantitativa delle abbondanze dei minerali argillosi (caolinite, illite, clorite e smectite) è stata effettuata mediante riprese diffrattometriche eseguite su preparati isorientati. una sospensione acquosa della frazione inferiore a 0.002 mm è stata omoionizzata con 6g di mgcl2 6h2o per 500 ml in bagno ad ultrasuoni e successivamente centrifugata a 4000 rpm (per 15 minuti). il campione è stato quindi depositato mediante pipetta su supporti in vetro e in refrattario, e lasciato essiccare. esso è stato successivamente esposto ai vapori di glicole etilenico (in stufa a 60°c per due ore) e a vari trattamenti termici (180°c e 600 °c), quindi sottoposto ai raggi x. per le analisi è stato utilizzato un diffrattometro philips x’pert, radiazione cukα (40 kv, 40 ma), monocromatore a grafite, indagando un intervallo angolare compreso tra 2° e 30° 2θ, velocità del goniometro 1° 2θ/min (step size 0.010; time per step 0.50; scan speed 0.02; detector reference slit 0.2 mm). sugli spettri così ottenuti, allo scopo di effettuare una stima semiquantitativa delle abbondanze relative dei soli minerali argillosi (espressi come percentuali di illite, smectite, caolinite e clorite) sono state misurate le aree di riflessi specifici, successivamente trasformate in percentuali di abbondanza attraverso appropriati fattori di correzione e formule (metodo di shaw et al., 1971 modificato da laviano, 1987). l’analisi chimica, effettuata mediante spettrometria dei raggi di fluorescenza (xrf, spettrometro philips pw 1400), ha permesso di ricavare le concentrazioni degli elementi maggiori (si, ti, al, p, fe, mg, mn, ca, na, k) espressi in termini della percentuale in peso degli ossidi costituenti normalizzati rispetto alla perdita per calcinazione (loi) e, per la grande maggioranza dei campioni, anche degli elementi in traccia (v, cr, co, ni, cu, zn, rb, sr, zr, ba, la, ce) espressi in termini di parti per milione (ppm). una descrizione dettagliata delle procedure adottate, che sono state specificamente standardizzate per l’analisi di ceramica e di materie prime argillose, è riportata in una recente pubblicazione 282 (hein et al., 2002). i risultati dell’analisi chimica sono stati elaborati anche con metodi di statistica multivariata (analisi discriminante) allo scopo di verificare quantitativamente la consistenza e la significatività dei “gruppi chimici” dandone opportuna rappresentazione grafica in uno spazio bidimensionale (buxeda, 1999). inoltre, come già accennato, è stata effettuata una simulazione sperimentale di un ciclo di produzione limitatamente ai materiali della formazione terravecchia ed alle argille di ficarazzi. sugli impasti sperimentali sono stati calcolati gli indici di plasticità e liquidità facendo riferimento alla normativa italiana cnr-uni 10014. con l’argilla allo stato plastico sono stati modellati dei provini parallelepipedi (con dimensioni pari a circa 40x20x8 mm), sottoposti, dopo essere stati essiccati a 100 °c, a sequenze di cottura in muffola (atmosfera ossidante) a diverse temperature (300 °c e 950 °c con permanenza alla temperatura di picco sempre pari a 3 ore) per la determinazione del ritiro lineare in cottura (rlc) e la produzione di sezioni sottili da descrivere al microscopio polarizzatore (leica lsp equipaggiato con fotocamera digitale leica dc200 interfacciata ad un pc). 3. inquadramento geologico e caratterizzazione stratigrafica delle argille studiate nel territorio siciliano gli affioramenti argillosi sono piuttosto diffusi e conferiscono un aspetto prevalentemente collinare a gran parte dell’isola. in sicilia le unità litostratigrafiche che sono costituite totalmente o in parte da depositi argillosi abbracciano praticamente tutto l’intervallo temporale nel quale si sviluppano le successioni sedimentarie siciliane, che va dal trias superiore (con le argille della fm. mufara) all’olocene. di seguito viene effettuato un inquadramento geologico delle potenziali fonti di materie prime argillose utilizzabili per la produzione ceramica che affiorano nella sicilia nord-occidentale. in figura 1 sono riportati gli schemi crono-bio-litostratigrafici in cui si collocano le unità campionate: argille di ficarazzi (fig. 1a), formazione terravecchia (fig. 1b), flysch numidico ed argille varicolori (fig. 1c). 3.1 argille di ficarazzi l’area di affioramento di tale formazione è collocata nel settore costiero a se di palermo. il campionamento delle argille di ficarazzi è stato effettuato in c.da olivella, nelle immediate vicinanze del sito archeologico di solunto (prima insediamento fenicio-punico e poi romano), a ficarazzi presso la foce dell’eleuterio e in c.da acqua dei corsari a palermo. le argille di ficarazzi (seguenza, 1873; brugnone, 1877) sono argille sabbiose, silt e sabbie fini, di colore azzurro-grigio se inalterate, con rare intercalazioni di calcisiltiti e calcareniti. questi depositi vengono datati al siciliano (ruggeri, 1979). i dati provenienti dal sondaggio a carotaggio continuo ficarazzi 1 hanno permesso di definire nel dettaglio la biostratigrafia delle argille del siciliano (ruggieri & sprovieri,1977; di stefano & rio, 1981; buccheri, 1984). lo spessore è di qualche decina di metri con un massimo, rinvenuto in perforazione, di circa 80 metri. nel sottosuolo essa si estende quasi uniformemente nel settore meridionale ed orientale della piana di palermo. la macrofauna ad ospiti nordici della parte sommitale di queste argille è data dai molluschi arctica islandica, mya truncata, panopea norvegica, buccinum undatum. l’associazione a foraminiferi è generalmente ben diversificata ed in un buono stato di conservazione, anche se in molti livelli è meno ricca dal punto di vista fossilifero con aumento delle concentrazioni di granuli detritici di natura silicatica come quarzo monocristallino, selce e feldspati. i foraminiferi bentonici sono nettamente dominanti con rapporto p/b compreso tra 5÷15%, valore tipico della zona di circalitorale superiore (80÷100 m di profondità). l’associazione a foraminiferi planctonici è caratterizzata dalla presenza di globorotalia inflata, globorotalia truncatulinoides excelsa, globigerinoides ruber, globigerina bulloides, neogloboquadrina pachyderma, turborotalita quinqueloba, globigerinita glutinata. tra i foraminiferi bentonici sono frequenti uvigerina peregrina, bolivina dilatata, melonis padanum, hyalinea baltica. quest’ultima specie insieme a globorotalia truncatulinoides excelsa permettono di “datare” questi sedimenti attribuendoli all’intervallo siciliano. 3.2 argille della formazione terravecchia l’area di affioramento di questa formazione si estende nella sicilia centrale ed occidentale. il nostro campionamento ha interessato le località del vallone garbinogara nel comune di termini imerese (nei pressi dell’importante sito archeologico di himera); nel territorio comunale di castellana sicula in c.da ponte e c.da donalegge (nei pressi del sito archeologico di muratore); polizzi generosa in c.da guglia. la formazione terravecchia (tortoniano superiore-messiniano inferiore), istituita da schmidt di friedberg (1964; 1965), è costituita da una successione prevalentemente terrigena; comprende depositi terrigeni e terrigeno-carbonatici con differenti granulometrie che permettono di separare la formazione in unità di rango inferiore. la formazione comprende dal basso verso l’alto: 1) conglomerati rossi e giallastri ad elementi carbonatici, arenacei e litici di granulometria variabile, con matrice sabbiosa e sabbie quarzose con intercalazioni di conglomerati, con spessori massimi di 150 m; 2) sabbie ed arenarie quarzose di colore grigio-giallastro che si interdigitano, verso l’alto, con 3) argille, siltiti argillose e argille sabbiose (250 m di spessore), con abbondanti clasti di taglia arenitica, in cui il quarzo è in genere dominante con mica e feldspato comuni. la formazione terravecchia affiora estesamente anche nella sicilia centrale e centro-meridionale (nel cosiddetto bacino di caltanissetta). la formazione presenta spessori variabili compresi tra alcune centinaia di metri e quasi 2000 m. l’attribuzione stratigrafica dei campioni di questa formazione è spesso problematica. rari sono infatti i livelli contenenti una associazione significativa a plancton calcareo. spesso si tratta infatti di depositi di mare basso (ambiente deltizio), con abbondanti foraminiferi bentonici e abbondante contenuto clastico. l’associazione a foraminiferi è qualitativamente mediocre o scarsa, caratterizzata da preservazione dei gusci da discreta a pessima, con cattiva preservazione. frequenti sono i foraminiferi rimaneggiati di sedimenti più antichi. l’associazione a foraminiferi planctonici in posto anche se scarsa è tipica delle biozone a g. montana et al. 283 fig. 1 (a) schema crono-bio-litostratigrafico del pliocene/pleistocene; per le biozone a foraminiferi platonici sono stati utilizzati gli schemi proposti da cita & gartner (1973) emendati da sprovieri (1993). (b) schema crono-bio-litostratigrafico dell’intervallo compreso tra la parte alta del serravalliano e la parte bassa del messiniano; per le biozone a foraminiferi platonici sono stati utilizzati gli schemi proposti da sprovieri et al. (1996; 2002). (c) schema esemplificativo crono-bio-litostratigrafico dell’intervallo compreso tra la parte del cretaceo inferiore e il langhiano. per i dati sulle comparse e scomparse dei foraminiferi platonici sono stati utilizzati gli schemi proposti da bolli & sounders (1985). (a) litho-bio-chronostratigraphic sketch of the plio-pleistocene time interval; for the planktonic foraminifera biozone the schemes proposed in cita & gartner (1973) and modified by sprovieri (1993) have been used. (b) litho-bio-chronostratigraphic sketch for the late serravallian-early messinian time interval; the schemes proposed by sprovieri et al. (1996; 2002), have been used for the planktonic foraminifera biozone. (c) simplified litho-bio-chronostratigraphic sketch of the early cretaceous-langhian time interval. for occurrences and disappearances of planktonic foraminifera schemes proposed by bolli & sounders (1985) have been used. definizione composizionale delle “argille ceramiche” ... 284 globigerinoides obliquus extremis, globorotalia suterae e globorotalia conomiozea che secondo lo schema biostratigrafico proposto da sprovieri et al., (1996), ricoprono la parte medio-alta del tortoniano e la parte bassa del messinano. nell’associazione sono frequenti orbulina universa, neogloboquadrina acostaensis, globorotalia menardii. i foraminiferi bentonici sono dominanti rispetto ai planctonici con un rapporto p/b che oscilla tra 10÷30% in cui ammonia beccarii, ammonia punctatogranosa sono dominanti seguiti, in percentuale di frequenza da florilus boueanum e elphidium crispum. 3.3 argille del flysch numidico in totale sono stati prelevati 8 campioni. le località di campionamento sono ubicate nei territori comunali di termini imerese (3 campioni) e caccamo (3 campioni), in punti più o meno prossimi al sito greco-coloniale di himera e nel territorio di isnello (2 campioni). al flysch numidico (oligocene superiore-miocene inferiore) appartengono le successioni clastico-terrigene, per lo più torbiditiche, che costituiscono le coperture, in gran parte scollate dal loro originario substrato mesozoico-terziario, dei domini imerese e panormide e di domini più interni (sicilidi). affiora estesamente in tutta la sicilia centro-settentrionale, ma si riconosce in lembi, con tipologie in parte differenti, anche nella sicilia occidentale (ca t a l a n o & d’ar g e n i o, 1982; catalano et al., 2000; 2002) e centro-meridionale. in sottosuolo raggiunge gli spessori più elevati, per imbricazioni tettoniche, nella sicilia centro-orientale (bianchi et al., 1989; bello et al., 2000). su base lito e biostratigrafica si possono distinguere tre unità litostratigrafiche (catalano et al., 2005): formazione di portella colla (oligocene superiore-aquitaniano), formazione geraci siculo (aquitaniano-burdigaliano) e formazione tavernola (burdigaliano-langhiano), generalmente eteropiche tra di loro. la formazione portella colla è costituita da argilliti di colore bruno o color tabacco, talora manganesifere, a cui si intercalano strati centimetrici di siltiti ed arenarie fini, e talora, livelli di megabrecce carbonatiche. nella parte inferiore sono presenti lenti bioclastiche con macroforaminiferi (nummuliti). lo spessore è di circa 500 m. la formazione geraci siculo è rappresentata da potenti banchi di quarzareniti con intercalazioni argillitiche. la formazione tavernola (marchetti, 1956) è costituita da marne e argilliti grigioverdi o biancastre, intercalate a livelli arenacei quarzosi e ricchi di granuli glauconitici, con una maggiore percentuale della componente carbonatica rispetto agli altri litotipi. lo spessore supera i 200 m. questi depositi sono stati descritti nei monti nebrodi (accordi, 1958; colacicchi, 1958), nelle madonie (ogniben, 1960; broquet, 1968) e nei monti di palermo (caflisch, 1966). il contenuto paleontologico degli intervalli marnosoargillosi è dato da radiolari, spicole di spugna, foraminiferi planctonici e bentonici, rari nannofossili calcarei. l’associazione della fm di portella colla è essenzialmente dominata da foraminiferi bentonici agglutinanti tra cui ammodiscus e glomospira, che meglio si adattano ai sedimenti torbiditici. l’associazione della formazione tavernola è caratterizzata dalla discreta presenza di foraminiferi planctonici che permettono una buona datazione stratigrafica di questi sedimenti. nella porzione inferiore la preservazione dei gusci dei foraminiferi è generalmente cattiva mentre l’associazione è dominata dalla presenza di globorotalia opima nana, cataspidrax dissimilis, globoquadrina dehiscens che indicano un età riferibile all’aquitaniano (iaccarino, 1985). i sedimenti più abbondanti sono però rappresentati da quelli del burdigaliano inferiore con rari individui di globigerinoides altiapertura, neogloboquadrina praecontinuosa, cataspidrax dissimilis (biozona cataspidrax dissimilis, (iaccarino, 1985), inoltre sono abbondanti gli individui di paragloborotalia acrostoma nei livelli del burdigaliano. la porzione più alta di questi sedimenti è caratterizzata dalla presenza di globigerinoides trilobus (biozona a globigerinoides trilobus) che indica il burdigaliano superiore (iaccarino, 1985). in rari campioni della formazione tavernola si ritrova praeorbulina glomerosa, la cui presenza permette di attribuire i sedimenti al langhiano inferiore (biozona praeorbulina glomerosa). 3.4 argille varicolari le località sottoposte a campionamento sono ubicate a c.da pantaleo (castellana sicula), c.da torre (polizzi generosa) ed a c.da cozzo del drago (himera), tutte nelle immediate vicinanze di importanti e documentati centri di produzione ceramica (polizzi) o di insediamenti di età arcaica e/o romana (himera e castellana sicula). le argille varicolori (cretaceo superioreoligocene inferiore) sono costituite da argille e marne varicolori rosso-verdastre con intercalazioni centimetriche di livelli silicizzati verdi, fortemente scagliettate e tettonizzate. questi depositi afferiscono al dominio paleogeografico sicilide (ogniben 1960), che si sviluppava presumibilmente su un originario basamento cristallino di tipo oceanico, dal quale attualmente risulta totalmente scollato. gli eventi deformativi che portarono alla messa in posto dell’edificio tettonico siciliano coinvolsero per prime proprio le unità sicilidi (miocene inferiore-medio), che si trovano nelle posizioni più elevate della pila tettonica. questi terreni, conosciuti anche con il nome di argille scagliose, sono diffusi nei settori orientali della sicilia, ma affiorano estesamente anche nella sicilia centro-occidentale e in lembi inglobati all’interno dell’edificio tettonico nella sicilia centromeridionale. in affioramento le argille varicolori sono spesso associate, con rapporti tettonici complessi, alle unità del flysch numidico. il contenuto micropaleontologico è mediamente caratterizzato dalla presenza di numerose specie di foraminiferi bentonici e planctonici che dal punto di vista stratigrafico ricoprono un intervallo che va dal cretaceo superiore sino all’oligocene inferiore. in alcuni particolari livelli del cretaceo superiore e dell’oligocene inferiore sono presenti anche abbondanti radiolari. nelle argille varicolori, a causa della forte tettonizzazione che hanno subito, è molto difficile ricostruire una stratigrafia continua che ricopra il cretaceo superiore-oligocene inferiore ed infatti l’intervallo stratigrafico appare spesso lacunoso. in particolare nella parte stratigraficamente più antica del cretaceo superiore le associazioni sono costituite da differenti specie di marginotruncana globotruncanita stuarti, rosita contusa, abatomphalus mayeroensis che indicano la parte alta del cretaceo. è molto difficile, invece, riconoscere o ritrovare l’intervallo stratigrafico del paleocene, mentre sono presenti varie g. montana et al. specie dell’eocene dell’inferiore-superiore tra cui, morozovella aragonensis, morozovella formosa, truncarotaloides rorhi, acarinina bulbrooki, turborotalia cerroazulensis. l’oligocene inferiore è caratterizzato dalla presenza di pseudohastigerina micra e cassigerinella chipolensis che permettono di riconoscere l’omonima biozona (iaccarino, 1985). 4. risultati e discussione 4.1 caratteristiche granulometriche le materie prime ceramiche oggetto di studio sono state sottoposte ad analisi granulometrica, a fini classificativi, seguendo la procedura precedentemente descritta. i risultati analitici, una volta proiettati nel diagramma ternario di shepard (1954) consentono di mettere in evidenza alcune interessanti differenze che, a loro volta, possono essere poste in relazione con la maggiore o minore diffusione avuta da tali materiali nella manifattura ceramica tradizionale del territorio in esame (fig. 2). come si può osservare in figura 2, innanzitutto, anche nell’ambito delle singole formazioni argillose esiste una dispersione più o meno marcata dei contenuti relativi di sabbia, silt e argilla tra i differenti punti di prelievo. i campioni rappresentativi delle argille di ficarazzi accoppiano una certa variabilità nell’abbondanza della frazione sabbiosa, che è generalmente alta, ad oscillazioni non trascurabili nel rapporto tra le due componenti fini (silt e argilla). i campioni prelevati dalla formazione terravecchia non formano un gruppo particolarmente omogeneo anche se, in grande prevalenza, sono classificabili come silt argillosi. la variabilità nella distribuzione granulometrica di queste argille sembra essere condizionata soprattutto dalle abbondanze relative del silt e della sabbia. da notare, in ogni caso, che la dimensione dei granuli sabbiosi in queste argille ricade prevalentemente nell’ambito della sabbia molto fine (0.06÷0.125 mm); raramente si hanno granuli con dimensioni maggiori di 0.2 mm. le argille del flysch numidico risultano essere caratterizzate da contenuti in sabbia sufficientemente costanti, per lo più prossimi o inferiori al 10% (in peso) e da proporzioni maggiormente variabili di particelle afferenti alle classi dimensionali fini, distribuendosi nei campi dei silt argillosi e delle argille siltose. le argille varicolori, rispetto alle altre tipologie analizzate, possiedono certamente la maggiore omogeneità granulometrica, risultando collocate, di conseguenza, in un intorno abbastanza circoscritto del diagramma triangolare (campo delle argille siltose). in tutti i campioni rappresentativi di questa formazione, si registra una netta predominanza delle frazioni granulometriche più fini (il tenore medio in particelle inferiori a 2 µm risulta essere intorno al 55%, quindi leggermente prevalente sul silt) ed un contenuto di sabbia generalmente basso, più o meno inferiore al 10%. in definitiva, tra i materiali analizzati, sono le argille della formazione terravecchia quelle che, tra tutte, possiedono le caratteristiche granulometriche più vicine ad un materiale argilloso effettivamente idoneo ad essere utilizzato come materia prima per la manifattura ceramica. infatti, esse hanno un rapporto equilibrato tra le componenti più fini (argilla e silt) che, associato ad un moderato contenuto in scheletro sabbioso fine e molto fine (anche se non particolarmente costante), le rende ipoteticamente utilizzabili tal quali, senza dover ricorrere a trattamenti preliminari più o meno complessi (setacciatura, decantazione, dimagrimento). 4.2 composizione mineralogica l’analisi mineralogica dei campioni di argilla mediante diffrattometria a raggi x (xrd) ha consentito di evidenziare qualità altrettanto significative che contribuiscono a valutare la maggiore o minore idoneità dei singoli materiali ai fini della produzione ceramica. in tabella 1, per ognuna delle quattro formazioni oggetto di studio, è riportata una stima semiquantitativa mediata delle abbondanze relative delle fasi mineralogiche rilevate dall’analisi del tout-venant. il quarzo risulta essere sempre la fase mineralogica predominante, indipendentemente dalla distribuzione granulometrica del sedimento. per quanto riguarda la calcite, mentre nelle argille di ficarazzi e nella formazione terravecchia questo minerale è abbondante o comune con un’abbondanza relativa verosimilmente proporzionale al contenuto di microfauna fossile dei campioni, nel caso delle argille varicolori mostra un’ampia variazione. questo risultato è certamente da correlare alla tettonizzazione che caratterizza questi materiali (argille scagliose); per cui, localmente, in corrispondenza dei fitti reticolati di sottili fessure, possono essere presenti mineralizzazioni secondarie di calcite. il flysch numidico è l’unica argilla caratterizzata da tenori in calcite sempre molto bassi. le altre fasi mineralogiche rilevate in piccole quantità o in tracce sono dolomite, mica, k-feldspato, plagioclasio ed ematite. tracce o piccole quan285 fig. 2 classificazione delle materie prime argillose della sicilia nord-occidentale mediante il diagramma ternario di shepard. classification of clayey raw materials from north-western sicily according the shepard's ternary diagram. definizione composizionale delle “argille ceramiche” ... tità di dolomite e mica sono state riscontrate solo nelle argille di ficarazzi e nella formazione terravecchia; mentre gli ossidi di ferro cristallino, sotto forma di ematite, appaiono relativamente più abbondanti nei depositi del flysch numidico e delle argille varicolori, sebbene siano sempre in quantità appena rilevabili. e’ interessante sottolineare che i campioni della formazione terravecchia si distinguono in modo caratteristico da tutte le altre argille oggetto di studio per la presenza di quantità relativamente maggiori di mica e feldspato. anche per quanto concerne le abbondanze relative dei minerali argillosi che caratterizzano la frazione inferiore ai 2 µm delle materie prime considerate è possibile evidenziare alcune differenze significative, come mostrato nell’istogramma di figura 3. le argille di ficarazzi risultano essere mediamente caratterizzate da quantità pressoché equivalenti di illite, caolinite e smectite (con leggera prevalenza delle ultime due fasi), mentre non è stata rilevata la presenza di clorite in nessuno dei campioni analizzati. invece, i campioni rappresentativi della formazione terravecchia mostrano, nel complesso, una chiara prevalenza dell’illite (in media circa il 40% del totale dei minerali argillosi), con caolinite e smectite relativamente meno abbondanti. da segnalare la presenza di una quantità di clorite stimata intorno al 10%. le argille del flysch numidico, sono le uniche in cui si registra una leggera prevalenza della caolinite sull’illite. anche la componente smectitica appare ben rappresentata (intorno al 25% del totale dei minerali argillosi), mentre la clorite risulta presente in quantità trascurabili. infine, le argille varicolori possiedono una composizione mineralogica abbastanza caratteristica che vede prevalere nettamente illite e smectite, soprattutto sotto forma di strati misti. queste due fasi insieme rappresentano oltre l’80% del totale dei costituenti argillosi. la caolinite è presente in quantità molto inferiori rispetto alle altre argille esaminate ed anche la clorite è presente in quantità molto piccole. anche in questo caso i materiali argillosi della formazione terravecchia sono quelli che sembrano essere, almeno teoricamente, quelli relativamente più adatti alla produzione ceramica. infatti, si tratta di argille illitiche con un contenuto in fillosilicati a reticolo espandibile relativamente meno significativo (al contrario delle argille varicolori e delle argille di ficarazzi), caratterizzate al tempo stesso da un equilibrato contenuto naturale in fondenti (calcite e feldspati). 4.3 composizione chimica (xrf) i risultati ottenuti dall’analisi chimica, riferiti agli elementi maggiori (espressi in % in peso e normalizzati rispetto alla perdita a fuoco) ed in traccia (espressi in ppm), sono presentati in tabella 2. 286 tab. 1 stima semiquantitativa ottenuta mediante analisi xrd delle fasi mineralogiche presenti nella frazione più grossolana (> 0.002 mm) dei materiali argillosi oggetto di studio. legenda: xxxx = molto abbondante; xxx = abbondante; xx = comune; x = piccole quantità; tr = tracce; = non rilevato. relative abundances of the mineralogical phases in the coarser fraction (> 0.002 mm) of the studied clayey materials carried out by xray diffraction analysis. legend: xxxx = very abundant; xxx = abundant; xx = common; x = few quantities; tr = trace; = lower than detection limit. fase mineralogica argille di ficarazzi argille terravecchia flysch numidico argille varicolori quarzo xxxx xxxx xxxx xxx calcite xx/xxx x/xx tr tr/xx dolomite tr tr mica tr x k-feldspato tr tr/x tr/x tr plagioclasio tr/x tr/x ematite tr tr tr fig. 3 abbondanze relative (valori medi) dei fillosilicati presenti nella frazione più fine delle argille studiate (< 0.002 mm). relative abundances (average values) of phyllosilicates detected in the finest fraction of the studied clays (< 0.002 mm). g. montana et al. 287 tab. 2 concentrazione elementi maggiori (% in peso) minori e in tracce (ppm) dei materiali argillosi ottenute con l’analisi xrf e normalizzate verso la perdita per calcinazione (l.o.i). mayor (wt%) and trace (ppm) element concentrations of the raw materials, obtained through xrf analysis and normalised versus l.o.i. sample sio2 tio2 al2o3 p2o5 fe2o3 mgo mno cao na2o k2o rb sr y zr cr ni ba la ce v hm 3 05.8 0.01 01.9 000. 0.07 0.03 000 0.09 0.01 0.02 120 289 29 285 109 53 230 30 76 138 hi.1 05.8 0.01 01.8 000. 0.07 0.03 000 0.08 0.01 0.02 117 240 26 217 89 56 257 38 68 145 hi.2 05.9 0.01 01.9 000. 0.07 0.03 000 0.08 0.01 0.03 131 257 28 240 96 61 234 35 81 147 hi.3 05.8 0.01 01.9 000. 0.08 0.03 000 0.07 0.01 0.03 108 211 22 187 110 61 250 36 81 147 hi.4 05.7 0.01 01.9 000. 0.09 0.03 000 0.08 0.01 0.03 112 232 24 211 92 56 236 39 90 131 hi.5 05.9 0.01 01.9 000. 0.07 0.03 000 0.08 0.01 0.02 117 246 26 243 102 54 237 32 80 133 hi.6 05.7 0.01 01.9 000. 0.09 0.03 000. 0.07 0.01 0.03 107 199 22 185 102 52 243 41 77 144 hi.7 05.8 0.01 01.8 000. 0.08 0.03 000 0.08 0.01 0.02 112 243 27 249 87 56 233 36 74 136 hi.8 05.8 0.01 01.9 000. 0.08 0.03 000 0.08 0.01 0.03 113 236 24 199 104 60 248 36 80 141 hi.10 05.9 0.01 01.9 000. 0.07 0.03 000 0.08 0.01 0.03 130 265 29 224 94 61 242 34 83 141 hi.11 05.7 0.01 01.9 000. 0.08 0.03 000. 0.08 0.01 0.03 104 221 22 180 103 51 259 36 78 140 hi.12 05.8 0.01 01.9 000. 0.07 0.03 000 0.08 0.01 0.03 121 237 24 210 101 53 234 39 93 145 hi.13 05.8 0.01 01.9 000. 0.09 0.02 000. 0.06 0.01 0.02 108 209 24 230 97 62 234 32 90 148 hi.14 05.9 0.01 01.9 000. 0.07 0.03 000 0.07 0.01 0.03 111 209 21 155 99 47 237 36 95 139 hi.15 05.9 0.01 01.8 000. 0.08 0.03 000 0.08 0.01 0.02 90 203 19 144 112 66 241 32 86 149 hi.16 05.8 0.01 01.9 000. 0.07 0.03 000 0.08 0.01 0.03 108 217 21 164 106 55 259 42 72 144 hi.18 05.8 0.01 02.0 000. 0.08 0.03 000 0.07 0.01 0.03 96 192 17 155 95 54 242 37 79 162 hi.19 05.9 0.01 01.9 000. 0.07 0.03 000 0.08 0.01 0.03 125 260 27 253 106 53 244 33 77 139 hi.20 06.0 0.01 01.8 000. 0.07 0.03 000 0.08 0.01 0.03 95 197 18 147 90 53 254 34 80 136 hi.21 05.8 0.01 01.9 000. 0.08 0.03 000 0.08 0.01 0.03 107 222 22 181 100 52 223 37 87 148 hi.22 05.8 0.01 01.9 000. 0.08 0.03 000 0.08 0.01 0.03 100 235 21 176 94 55 234 33 101 144 hi.23 05.8 0.01 01.8 000. 0.07 0.03 000 01.0 0.01 0.02 101 264 22 203 97 54 241 35 72 135 hi.24 05.7 0.01 01.9 000. 0.09 0.03 000. 0.08 0.01 0.03 102 221 21 178 95 53 244 36 87 149 fct1 05.9 0.01 01.9 000. 0.07 0.03 000 0.07 0.01 0.03 100 198 18 173 122 49 266 34 70 165 fct2 06.1 0.01 01.7 000. 0.07 0.03 000 0.07 0.01 0.03 119 235 24 200 146 61 316 42 75 173 fct3 06.2 0.01 01.6 000. 0.06 0.03 000 0.08 0.01 0.02 105 131 12 89 95 37 270 38 77 122 fct4 06.0 0.01 01.7 000. 0.06 0.03 000 0.08 0.01 0.02 112 195 18 181 104 45 286 40 80 134 media 05.9 0.01 01.9 000. 0.07 0.03 000 0.08 0.01 0.03 110 225 23 195 102 54 248 36 81 144 sample sio2 tio2 al2o3 p2o5 fe2o3 mgo mno cao na2o k2o rb sr y zr cr ni ba la ce v camp. 1 52,78 1,29 20,35 0,07 8,53 1,84 0,03 0,57 0,09 1,93 n.m. n.m. n.m. n.m. n.m. n.m. n.m. n.m. n.m.n.m. camp. 2 05.8 0.01 02.5 000. 01.0 0.02 000 0.01 000. 0.02 135 231 44 201 124 n.m. 367 72 146 286 camp. 3 06.0 0.01 02.3 000. 0.09 0.02 000. 0.01 000. 0.02 99 126 22 134 101 n.m. 389 48 98 206 camp. a 64,52 1,12 21,72 0,12 7,39 1,71 0,04 1 0,27 2,1 139 184 29 191 73 n.m. 334 98 198 211 camp. c 61,66 1,1 21,55 0,12 8,27 2,5 0,21 1,68 0,2 2,71 202 235 38 200 165 n.m. 519 56 124 334 camp. d 63,94 1,07 21,83 0,12 8,05 1,75 0,03 0,85 0,32 2,05 161 364 38 185 146 n.m. 531 50 108 309 camp. e 60,06 1,25 24,38 0,09 8,16 2,5 0,11 0,57 0,4 2,5 154 807 33 110 113 n.m. 438 33 65 232 camp. f 63,25 1,25 23,01 0,06 6,47 2,32 0,03 0,27 0,42 2,91 201 163 26 188 84 n.m. 495 99 232 240 media 06.1 0.01 02.3 000. 0.08 0.02 000 0.01 000. 0.02 156 301 33 173 115 n.m. 439 65 139 260 sample sio2 tio2 al2o3 p2o5 fe2o3 mgo mno cao na2o k2o rb sr y zr cr ni ba la ce v f1 06.0 0.01 01.8 000. 0.08 0.03 000 01.0 000. 0.01 50 261 21 282 74 27 186 28 70 100 s1 05.9 0.01 01.8 000. 0.07 0.02 000 0.09 0.02 0.02 97 272 23 250 92 30 167 33 83 119 ac1 05.9 0.01 01.8 000. 0.07 0.03 000 01.0 000. 0.02 84 335 20 218 67 26 204 29 73 115 ac2 05.8 0.01 01.5 000. 0.06 0.03 000 01.4 0.01 0.02 68 351 25 181 59 24 187 21 60 100 media 05.9 0.01 01.7 000. 0.07 0.03 000 01.1 0.01 0.02 07.5 305 22 232 73 27 186 28 71 109 sample sio2 tio2 al2o3 p2o5 fe2o3 mgo mno cao na2o k2o rb sr y zr cr ni ba la ce v hm 4 06.1 0.01 02.2 000 0.08 0.02 000. 0.01 0.02 0.03 181 227 30 188 108 65 271 39 80 134 camp. 7 63,49 0,8 18,13 0,1 8,48 2,94 0,12 1,57 1,23 3,33 268 451 36 111 96 n.m. 305 40 79 245 av1 05.8 0.01 02.4 000. 0.08 0.03 000 0.03 0.01 0.02 80 354 20 225 167 51 138 48 90 165 av2 06.0 0.01 02.1 000. 0.07 0.03 000 0.04 0.01 0.02 81 123 14 108 234 44 117 41 83 308 av3 05.8 0.01 02.7 000. 0.08 0.02 000. 0.01 0.01 0.02 88 131 18 132 233 61 168 44 87 276 av4 05.8 0.01 01.8 000. 0.08 0.03 000. 0.09 0.02 0.02 84 295 25 119 116 69 147 44 88 161 av5 06.1 0.01 01.9 000. 0.08 0.03 000. 0.05 0.02 0.02 75 226 12 107 112 69 124 41 81 151 media 06.0 0.01 02.1 000. 0.08 0.03 000. 0.03 0.01 0.02 122 258 22 141 152 60 181 42 84 206 f o r m a z io n e t e r r a v e c c h ia f l y s c h n u m id ic o a r g il le d i f ic a r a z z i a r g il l e v a r ic o l o r i definizione composizionale delle “argille ceramiche” ... già un primo esame sommario consente di apprezzare alcune differenze sostanziali nel chimismo dei vari campioni argillosi che possono essere considerate in buon accordo con quanto già osservato mediante le analisi mineralogiche e, in misura minore, anche con le specifiche caratteristiche di distribuzione granulometrica. tra gli ossidi degli elementi maggiori soltanto i tenori in sio2 e p2o5, non sembrano in alcun modo possedere i requisiti per essere considerati come “markers” di una delle formazioni argillose studiate, data la sostanziale corrispondenza dei valori medi e dei campi di variazione. al contrario, i valori medi delle concentrazioni in cao, al2o3, fe2o3, k2o, na2o, tio2, mgo ed mno, specie se utilizzati in modo incrociato, sembrano poter fornire criteri sufficientemente efficaci per differenziare tra loro le materie prime. tuttavia, occorre sottolineare che la maggior parte di queste variabili non può essere considerata, allo stato attuale degli studi, come “marker” peculiare di una singola tipologia di argilla. i depositi del flysch numidico e delle argille varicolori si distinguono dagli altri per le concentrazioni mediamente più alte in al2o3 (superiori al 21% in peso), fe2o3 (intorno all’8% in peso) ed mno (pari o superiori allo 0.1 % in peso), come pure per i tenori medi estremamente più bassi in cao (rispettivamente 0,89 e 3.35% in peso). inoltre, in particolare, le argille del flysch numidico sono caratterizzate anche da un tenore molto basso in na 2o, in media corrispondente allo 0.31% in peso e con un campo di variazione molto ristretto (dallo 0.09% allo 0,49% in peso), oltre che da valori in tio2 mediamente più alti e sempre superiori all’1% in peso. le argille di ficarazzi, tra tutte quelle prese in considerazione in questo studio, risultano differenziate dalla maggiore concentrazione media in cao (superiore al 10% in peso) e da valori relativamente più bassi di al2o3, fe2o3 e k2o. anche il tenore in na 2o appare sostanzialmente modesto rispetto agli altri materiali (ad esclusione del flysch numidico), nonostante il valore medio risenta molto di un campione (s1) prelevato in affioramento a pochi metri dalla battigia (presso la spiaggia dell’olivella a poche centinaia di metri dall’insediamento fenicio-punico di solunto) e quindi evidentemente contaminato da sale marino. i materiali prelevati dagli affioramenti della formazione terravecchia sono caratterizzati da tenori in cao intermedi (inferiori all’8% in peso) e da una concentrazione di k2o relativamente più elevata, specialmente rispetto alle argille di ficarazzi. questa caratteristica può essere correlata alla presenza di mica e feldspato come effettivamente rilevato nel corso delle analisi xrd. in figura 4 sono tra loro confrontati i campi di variazione composizionale ed i valori medi di alcuni degli ossidi degli elementi maggiori più significativi ai fini della differenziazione delle materie prime ceramiche (cao, al2o3, fe2o3 e k2o). innanzitutto, ad esclusione del cao, deve essere sottolineata una notevole sovrapposizione dei campi di variazione degli elementi considerati, contrapposta a 288 fig. 4 diagrammi comparativi degli intervalli di variazione delle concentrazioni (espresse in % in peso) e dei relativi valori medi per alcuni tra gli elementi maggiori considerati più significativi nelle argille studiate. comparative plots of the variation of concentration values and corresponding averages of the most significative major elements oxides (wt %) in the studied clays. g. montana et al. differenze più o meno significative dei valori medi. per ciò che riguarda il cao, le argille varicolori possiedono il campo di variazione più esteso e sono, altresì, caratterizzate da una disposizione asimmetrica del valore medio (verso i valori più bassi dell’intervallo). quest’ultimo aspetto può essere compreso considerando che 6 campioni su un totale di 7 hanno un tenore in cao ben al di sotto del 5% ed un solo campione, che ne possiede l’8.68% in peso, crea la variabilità rilevata. anche il valore mediano (3.22%) risulta prossimo alla media aritmetica (3.35%). una certa variabilità del contenuto in cao con disposizione marcatamente asimmetrica del valore medio si registra anche per le argille di ficarazzi. tuttavia, questo risultato deve essere considerato con prudenza dato che il numero dei campioni analizzati è, come precedentemente spiegato, forzatamente piccolo. le argille del flysch numidico possiedono una variabilità estremamente ristretta del contenuto in cao ed il valore medio si dispone in modo simmetrico nell’intervallo dei valori. anche le argille della formazione terravecchia sono caratterizzate da un campo di variazione in cao ristretto e da un valore medio rappresentativo. l’esame dei campi di variazione relativi agli altri elementi suggerisce una variabilità contenuta della concentrazione di al2o3 e relativamente più ampia per i tenori di fe2o3 e k2o nel caso dei materiali argillosi del flysch numidico. le argille di ficarazzi ed i materiali della formazione terravecchia mostrano intervalli di variazione molto ristretti ed abbastanza piccoli anche in k 2o, mentre sono caratterizzati da una maggiore variabilità del contenuto in fe2o3. le argille varicolori, infine, sono differenziate dagli altri materiali per un campo di variazione particolarmente limitato in fe2o3 e, al contrario, possiedono un intervallo di relativamente più ampio per quanto riguarda i contenuti di k2o e al2o3, con disposizione marcatamente asimmetrica dei valori medi. in definitiva, soprattutto attraverso il rapporto cao/al2o3 le argille del flysch numidico e, in genere, anche le argille varicolori possono essere chiaramente differenziate dai campioni rappresentativi della formazione terravecchia (che a loro volta formano un gruppo assai omogeneo) e dalle argille di ficarazzi. queste ultime, invece, risultano mediamente più povere in allumina e più ricche in cao rispetto ai materiali miocenici (fig. 5a). in ogni caso, entrambe possono essere classificate come “argille calcaree” (cao > 5% secondo maniatis & t i t e , 1978), al contrario dei materiali del flysch numidico e delle argille varicolori che sono da considerare “argille non calcaree” (cao < 5%). l’esame dei risultati relativi agli elementi in traccia lascia intravedere, in primo luogo, una ragionevole connessione con gli elementi maggiori geochimicamente affini, ovvia conseguenza delle caratteristiche mineralogiche dei materiali esaminati. attraverso semplici diagrammi binari può essere verificata, ad esempio, la buona correlazione del k2o sia con il rb che con il ba, verosimilmente collegabile con il contenuto in mica e feldspato (fig. 5b, 5c). al tempo stesso, è possibile ottenere una soddisfacente discriminazione tra le argille oggetto di studio, con concentrazioni molto simili (con rare eccezioni) per tutti i campioni della formazione terravecchia, relativamente più basse per le argille di ficarazzi e gran parte delle argille varicolori, decisamente più alte nel caso dei materiali argillosi del flysch numidico. anche il confronto dei tenori in terre rare consente di confermare una volta ancora la notevole omogeneità composizionale delle argille della formazione terravecchia e, al contrario, la grande variabilità dei materiali del flysch numidico, che, anche 289 fig. 5 diagrammi binari: (a) cao-al2o3; (b) bak2o; (c) rbk2o (d) ce-la; (e) ni-cr. binary diagrams: (a) cao-al2o3; (b) bak2o; (c) rbk2o (d) ce-la; (e) ni-cr. definizione composizionale delle “argille ceramiche” ... in questo caso, sono caratterizzati da valori tendenzialmente più elevati rispetto alle altre argille (fig. 5d). infine, il diagramma binario tra cr e ni (fig. 5e) dimostra che attraverso questi elementi è possibile discriminare in modo accettabile le argille di ficarazzi dalle argille della formazione terravecchia, con queste ultime caratterizzate da tenori medi in entrambi gli elementi superiori di circa il 50%. 4.4 simulazione del ciclo produttivo come già anticipato in precedenza, soltanto le argille di ficarazzi (pleistocene) e le argille della formazione terravecchia (miocene) sono state sottoposte ad una simulazione di ciclo produttivo e ad analisi di tipo tecnologico. questa decisione è scaturita da evidenze etnografiche, archeologiche ed archeometriche che inducono a considerarle, con un buon margine di sicurezza, le materie prime più utilizzate per la produzione ceramica nel territorio oggetto di studio (alaimo et al., 2002; 2003; montana et al.., 2003). com’è noto, le caratteristiche macroscopicamente più evidenti di un impasto ceramico, quali la sua lavorabilità allo stato plastico, il comportamento in seguito ad essiccamento e cottura ed il colore del prodotto finito rappresentano le proprietà specifiche tenute empiricamente sotto controllo dagli antichi artigiani. queste caratteristiche erano giustamente considerate le più efficaci per selezionare le materie prime disponibili nello specifico contesto territoriale, allo scopo di mettere a punto una catena operativa completa e tecnologicamente avanzata, per la realizzazione di manufatti ceramici che garantissero, al tempo stesso, una soddisfacente funzionalità, un alto livello qualitativo e/o costi di produzione contenuti. la quantificazione dei sopraccitati parametri nelle argille di ficarazzi e nelle argille della formazione terravecchia è stata fatta, pertanto, per ottenere indicazioni utili ad una migliore comprensione delle scelte tecnologiche fatte dagli artigiani sicelioti, anche più di duemila anni addietro. inoltre, la simulazione del processo produttivo (manifattura di impasti sperimentali e cottura a temperature ben definite) è stata intrapresa anche per perseguire l’obiettivo, non meno importante, di provvedere ad una descrizione petrografica degli impasti ottenibili con le argille campionate. i dati petrografici possono successivamente essere utilizzati per effettuare attendibili confronti con reperti archeologici e/o i manufatti ceramici di età storica sospettati di essere stati prodotti con le stesse materie prime. 4.4.1 plasticità, colore e ritiro lineare la plasticità è un particolare comportamento reologico che i materiali argillosi manifestano con l’aggiunta un’appropriata quantità di acqua. essa consiste nella capacità del materiale stesso di assumere una deformazione permanente senza perdita di coesione e conseguente formazione di fessure. questa proprietà è controllata da diversi fattori, tra cui, soprattutto, l’abbondanza relativa dei minerali argillosi a reticolo espandibile nella frazione minore di 2 µm, la ripartizione delle varie frazioni granulometriche, nonché la presenza di materia organica. una procedura semplice ed allo stesso tempo attendibile comunemente usata per la determinazione della plasticità dei materiali argillosi di potenziale utilizzo ceramico è quella basata sulla misura degli indici di atterberg (marsigli & dondi, 1997). i limiti di consistenza dei materiali incoerenti come le terre argillose, molto schematicamente, vengono definiti dal contenuto di acqua che convenzionalmente caratterizza il passaggio dallo stato di fluido viscoso a quello plastico (limite di liquidità wl) e dallo stato plastico a quello semisolido (limite di plasticità wp). il contenuto di acqua per cui il materiale permane allo stato plastico è definito dall’indice di plasticità ip, ottenuto dalla differenza tra il limite liquido e quello plastico. i risultati relativi alle determinazioni empiriche dei limiti di atterberg ed al calcolo dell’indice di plasticità sono riportati in tabella 3. 290 tab. 3 limiti di atterberg relativamente ai campioni delle argille di ficarazzi e della formazione terravecchia. atterberg’s consistency limits of samples belonging to ficarazzi and terravecchia clayey’s formations. campione wl % wp % ip % argille di ficarazzi f1 49 21 28 s1 70 27 43 ac1 39 18 21 ac2 38 20 18 argille terravecchia hi1 44 21 23 hi2 47 25 22 hi3 49 27 22 hi4 46 24 22 hi5 45 22 23 hi6 45 21 24 hi7 42 24 19 hi8 52 18 34 hi10 45 22 23 hi14 46 21 25 hi16 47 22 25 hi18 51 20 31 hi19 45 18 27 hi20 42 21 21 hi21 48 18 29 hi22 48 19 30 hi23 41 19 22 fct1 53 26 27 fct2 55 35 21 fct3 42 21 21 fct4 40 24 16 entrambe le tipologie di materiale, nella grande maggioranza dei casi, risultano caratterizzate da valori accettabili di limite di liquidità e di indice di plasticità, tali da poter essere definite come argille di “media plasticità”. in particolare, i valori riferiti alle argille della formazione terravecchia dimostrano anche una buona omogeneità, con un indice di plasticità medio ip = 24%, sempre abbondantemente inferiore alla soglia del 40% che contraddistingue i materiali molto plastici e, pertanto, non idonei (tal quali) all’impiego come materia prima ceramica. questo comportamento è una diretta conseg. montana et al. guenza della loro ottimale distribuzione granulometrica, ed anche della netta predominanza di minerali argillosi a reticolo non espandibile (illite e caolinite), rispetto alla smectite, nella frazione inferiore ai 2 µm. anche i campioni rappresentativi delle argille di ficarazzi possiedono un valore medio dell’indice di plasticità accettabile, sebbene leggermente più elevato (ip = 27%) rispetto ai materiali della formazione terravecchia. questo risultato, tuttavia, è condizionato dal campione s1 che, come già accennato, è parzialmente contaminato da sale marino, la cui presenza influisce notevolmente sul limite liquido wl (e quindi sull’indice di plasticità). inoltre, occorre considerare anche la maggiore abbondanza di smectite di queste argille pleistoceniche (in media il 38% del totale dei minerali argillosi) decisamente più alta rispetto ai materiali miocenici della formazione terravecchia (in media pari al 24% del totale dei minerali argillosi). ad ogni modo, i campioni di entrambe le tipologie di materiale oggetto di studio, se proiettati nel diagramma di marsigli & dondi (1997) che mette in relazione limite liquido ed indice plastico, fornendo uno schema di previsione del comportamento in foggiatura delle argille per terracotta e laterizi, ricadono in grande prevalenza nei campi delle “argille impasto” e delle “argille base” (fig. 6). quindi, sono da considerare materiali che, in linea di massima, possiedono naturalmente una plasticità ottimale per la lavorazione o, secondo la destinazione d’uso dell’oggetto, necessitano di piccole correzioni attraverso l’aggiunta di opportune quantità di degrassante sabbioso, oppure la miscela con altre argille più magre. anche il ritiro lineare in seguito ad essiccamento e cottura è un parametro utile nella caratterizzazione di una materia prima argillosa, poiché consente di valutare empiricamente l’idoneità del materiale stesso ad essere utilizzato, tal quale, per la produzione di ceramica. in linea di massima, ad un limitato ritiro lineare, sia in fase di essiccamento che di cottura, corrisponde una maggiore idoneità teorica dell’argilla a fungere da materia prima ceramica, in quanto vi è un minor rischio che si formino fessure in seguito a ritiro differenziale. il ritiro lineare nell’intervallo 25÷100°c è legato alla perdita dell’acqua di impasto e dell’umidità intrappolata. il ritiro tra 100°c e 950°c è, invece, dovuto alla espulsione dell’acqua strutturale (a partire da circa 600°c), al processo di decarbonatazione (750÷900°c), alla produzione di fasi di neoformazione (a partire da 850÷900°c). le medie dei valori rilevati nei campioni della formazione terravecchia e nelle argille di ficarazzi sono graficamente rappresentate nell’istogramma di figura 7. il ritiro lineare si attesta al di sotto del 10% e con incrementi prossimi o inferiori all’1% e quindi, in linea di massima, è da ritenersi accettabile per entrambe le litologie. tuttavia, i materiali della formazione terravecchia mostrano un comportamento relativamente migliore rispetto alle argille di ficarazzi soprattutto in fase di essiccamento ed a basse temperature di cottura (ritiri minori di circa l’1÷1.5%), mentre la differenza sembra attenuarsi leggermente alle alte temperature. tali risultati possono essere interpretati considerando quanto emerso dalle analisi granulometriche e mineralogiche (xrd) che hanno messo in luce una più equilibrata distribuzione granulometrica per le argille della terravecchia rispetto alle argille di ficarazzi, che, inoltre, sono caratterizzate dalla presenza di una maggiore quantità di minerali argillosi a reticolo espandibile nella frazione inferiore a 2 µm. un fattore che può contribuire a ridurre il ritiro lineare alle temperature più alte è il contenuto in caco3, che, come visto, dalle analisi mineralogiche e chimiche, è in media relativamente più abbondante nelle argille pleistoceniche. infatti, durante il processo di cottura, successivamente alla decarbonatazione 291 fig. 6 schema di previsione del comportamento in foggiatura delle argille in accordo a quanto proposto da marsigli & dondi (1997). diagram for estimating moulding behaviour of clays after marsigli & dondi (1997). fig. 7 confronto tra i valori medi di ritiro lineare (%) mostrati dalle argille di ficarazzi e dalle argille della formazione terravecchia in seguito a cottura a diverse temperature. comparison between the average values of linear shrinkage (%) showed by the ficarazzi and terravecchia clayey’s formations after firing treatments at various temperatures. definizione composizionale delle “argille ceramiche” ... abbiamo reazioni che conducono alla formazione di nuove fasi cristalline (come gehlenite e pirosseno calcico) che contrastano, in linea di massima, la contrazione del prodotto ceramico. la variazione cromatica dei provini sottoposti a cottura sperimentale è mostrata in tabella 4, valutata mediante i codici alfanumerici di munsell (munsell soil colour charts). come noto, lo sviluppo del colore nella ceramica è legato a processi chimico-fisici che, fondamentalmente, dipendono dalla composizione chimica del materiale di partenza, dalle temperature massime raggiunte e dalla abbondanza di ossigeno nella camera di cottura (atmosfera ossidante o riducente). il colore di un manufatto ceramico è condizionato in modo prevalente dalla presenza di fe++ e fe+++, presenti negli ossidi, ovvero accolti nel reticolo cristallino delle fasi silicatiche che si sviluppano in cottura (gehlenite e pirosseno). secondo recenti studi gli elementi chimici ai quali è possibile attribuire un’influenza più o meno importante sul colore dei prodotti ceramici sono ferro, calcio, alluminio, titanio, e magnesio (fabbri & dondi, 1995); tra questi, risulta in tal senso determinante la concentrazione di cao e, ancora di più, il rapporto fe2o3 /cao. già alla temperatura di 300 °c i campioni delle due argille mostrano un primo cambiamento di colore che aggiunge, alla precedente tinta (hue) del giallo (5y) o del grigio (gley), una prima componente del rosso (5yr; 7,5yr). questo cambiamento può essere attribuito all’avanzare del processo di disidratazione dei minerali argillosi e degli ossidi di ferro presenti nel materiale. assai più consistenti, invece, sono le modifiche di tinta alle elevate temperature. infatti, a 950 °c è pressoché del tutto completo il processo di formazione delle nuove fasi mineralogiche, come la gehlenite, il diopside e/o la wollastonite; mentre l’ematite va assumendo una cristallinità sempre maggiore. le quantità relative di questi nuovi composti, oltre a conferire una nuova struttura al prodotto finito, contribuiscono a determinare il colore finale. alla temperatura di 950 °c, in un atmosfera di cottura e di raffreddamento pienamente ossidante (come si osserva in tabella 4), nelle tipologie di argilla oggetto di studio domina la tinta del rosso (2.5yr), essendo entrambi i materiali caratterizzati da un rapporto fe2o3/cao compreso tra 0.7 e 1. 4.4.2 descrizione petrografica ed esempi di determinazione di provenienza per alcune classi di reperti archeologici la caratterizzazione petrografica dei provini realizzati con le argille di ficarazzi e le argille della formazione terravecchia è stata effettuata valutando distribuzione, addensamento, granulometria e composizione mineralogica del degrassante. per la stima visiva sono state utilizzate delle tavole comparative (terry & chalingar,1955; bullock et al.,1985; tucker,1981) l’impasto delle argille della formazione terravecchia è caratterizzato un degrassante con, in genere, una grande prevalenza della sabbia molto fine (0.06÷0.125mm) rispetto alla sabbia fine (0,125÷0,25 mm). rari i granuli con dimensioni maggiori di 0.25 mm. l’addensamento risulta piuttosto variabile, prevalentemente compreso tra 5 e 15%; molto raramente raggiunge valori più alti intorno al 25%. il costituente principale è il quarzo monocristallino, rappresentato da frammenti subangolosi o sporadicamente subarrotondati (fig. 8a-b). la calcite, rappresentata da microfossili e, in misura minore, anche da frammenti litici è un costituente da comune a sporadico, sempre subordinato rispetto al quarzo monocristallino. minute lamelle di mica e piccoli frammenti di feldspato sono presenti in tutti i campioni analizzati e, sebbene in piccole quantità, possono essere considerati elementi caratteristici dell’impasto. componenti da assai subordinati a rari sono minerali opachi, clorite, glauconite, dolomite e litici cristallini acidi. tra i minerali accessori sono stati sporadicamente individuati apatite, zircone, rutilo e tormalina. nei provini cotti ad alta temperatura (950°c) i componenti di natura calcarea non sono più visibili, se non indirettamente, attraverso pori da impronta con orlo di schiarimento e/o micritic clots, vale a dire grumi di calcite microcristallina derivanti dalla ricarbonatazione dell’ossido di calcio nella fase di raffreddamento (cau et 292 litologia campioni 100°c 300°c 950° c fe2o3/cao f1 2.5y 5.5/1 10yr 5.5/3 5yr 6/5 0.8 argille di ficarazzi s1 2.5y 6.5/4 5yr 5/5 2.5yr 7/5 1.0 ac1 2.5y 6.5/4 5yr 5.5/5 2.5yr 6.5/8 0.7 ac2 2.5y 6.5/6 5yr 5.5/7 2.5yr7/6 0.5 hm 3 5y 5.5/1 10yr 5.5/3 7.5yr 6.5/4 0.8 hi 3 5y 6.5/1.5 7.5yr 5.5/3 5yr 5.5/7 1.1 hi 6 7.5y 7/1 10yr 5.5/2 2.5yr 5.5/6 1.3 hi 9 5y 6.5/1.5 10yr 6/4 2.5yr 6/6 0.7 hi 11 5y 6/1.5 7.5yr 5/3 5yr 6.5/5 0.9 argille terravecchia hi 12 5y 5.5/1 10yr 6/2.5 5yr 6.5/6 0.9 hi 19 2.5y 6/1.5 7.5yr 5.5/4 2.5yr 6/7 1.0 fct1 gley1 6/10y 10yr 5.5/2 2.5yr 5.5/8 1.0 fct2 gley1 6/5 gy 2.5y 5/2 2.5yr 5.5/6 1.0 fct3 gley1 6/10y 10yr 5/3 2.5yr 5.5/7 0.7 fct4 gley1 6.5/10y 10yr 5.5/2 2.5yr 5/7 0.8 tab. 4 colori secondo i codici munsell mostrati dai campioni delle argille di ficarazzi e della formazione terravecchia dopo cottura in atmosfera ossidante alle temperature di 100, 300 and 950°c. munsell colours showed by ficarazzi and terravecchia clayey’s samples after oxidizing firings at 100, 300 and 950°c. g. montana et al. al., 2002). l’impasto delle argille di ficarazzi risulta caratterizzato da un degrassante sabbioso con distribuzione granulometrica seriale. anche in questo caso prevale la sabbia molto fine (0,06÷0,125 mm) ma, a differenza delle argille precedentemente descritte, si hanno anche quantità relativamente minori, ma non trascurabili, di sabbia fine o media, e, più raramente, anche granuli con dimensione grossolana o molto grossolana (0.5÷2 mm). l’addensamento della frazione sabbiosa appare assai variabile, in genere compreso dal 10 al 25% ma può raggiunge valori anche molto più alti, sino ad oltre il 20%. il costituente predominante è il quarzo monocristallino contraddistinto da frammenti angolosi o subangolosi, seguito da quantità variabili da abbondanti a comuni di litoclasti e bioclasti calcarei. costituenti sempre presenti e caratterizzanti, benché in piccole quantità, risultano essere dei frammenti subarrotondati di quarzarenite, granuli selce, quarzo policristallino e kfeldspato (fig. 8c-d). tra i minerali accessori si segnala apatite (rara). anche in questo caso, come ovvio aspettarsi, dopo la cottura a 950°c la componente calcarea non è più visibile in nessuno dei campioni esaminati se non per mezzo di pori da impronta e/o micritic clots. come già sottolineato, uno dei risultati più importanti che ci si aspetta dalle analisi archeometriche sulle materie prime è dato dalla attestazione degli elementi distintivi dell’impasto realizzato in un dato centro di produzione, ed il controllo di eventuali variazioni nel tempo legate a differenti procedure tecnologiche, ovvero alla tipologia e alla destinazione d’uso dell’oggetto ceramico. questi aspetti, di grande ricaduta archeologica, hanno lo scopo di caratterizzare le manifatture locali e distinguerle dalle importazioni in specifici contesti di scavo, ben delimitati geograficamente e cronologicamente. per ogni categoria ceramica ritenuta di interesse, un confronto su base composizionale con le potenziali materie prime costituirebbe un criterio altamente oggettivo al fine di attestarne la produzione locale. inoltre, qualora si pensi che la stessa classe ceramica possa avere avuto una confacente diffusione in ambito regionale, o persino extraregionale, da questo tipo di studi potrebbe aversi anche un notevole apporto nella ricostruzione dei circuiti commerciali che, troppo spesso, ancora oggi, risulta quasi esclusivamente basata sul confronto morfologico e stilistico dei reperti. a scopo esemplificativo ed anche per verificare la reale significatività dei dati acquisiti sulle argille della sicilia nord-occidentale, è stato ritenuto utile effettuare un confronto tra le nostre materie prime con alcune classi di reperti ceramici già caratterizzati composizionalmente in studi precedenti. in particolare, sono state prese in considerazione classi di materiali di produzione accertata, o verosimilmente ipotizzata, nello stesso territorio (sicilia nord-occidentale) in epoche anche molto differenti: mattonelle da pavimentazione di produzione palermitana, datate dal xvi al xix secolo (alaimo et al., 2004); piatti e coppe decorate con vernice nera, di età ellenistica, provenienti da scavi effettuati a palermo, termini imerese, marineo e monte iato, ritenute imitazioni locali della produzione nota come campana a (belvedere et al., in stampa)2; coppe di età arcaica, note come iato k480, ritenute produzioni indigene derivate da analoghe forme attiche, ritrovate ad himera ed altri siti minori circostanti (vassallo, 1996; alaimo et al., 2000). dal confronto dei dati petrografici (osservazioni al microscopio polarizzatore delle sezioni sottili) inerenti le sopraccitate classi di reperti ceramici e i prodotti finiti ottenuti dagli impasti sperimentali delle argille selezionate risulta che i gruppi di reperti corrispondenti alle imitazioni di ceramica a vernice nera in forma di campana a ed alle mattonelle maiolicate del xvii secolo presentano caratteristiche composizionali e tessiturali del tutto compatibili con le argille di ficarazzi. esistono, infatti, forti somiglianze in termini 293 fig. 8 immagini al microscopio polarizzatore (nicol incrociati; barra dimensionale = 0.5 mm): argille della formazione terravecchia cotte a 300 °c (a) ed a 950 °c (b); argille di ficarazzi cotte a 300 °c (c) ed a 950 °c (d). images at the polarizing microscope (crossed nicol; scale bar = 0,5 mm): terravecchia formation clay after firing treatments at 300 °c (a) and 950 °c (b); ficarazzi clay after firing treatments at 300 °c (c) and 950 °c (d). definizione composizionale delle “argille ceramiche” ... 2per campana a si intende una ceramica da mensa assai pregiata, decorata a vernice nera, il cui centro di produzione è stato individuato nell’area della baia di napoli, ampiamente esportata nel mediterraneo occidentale a partire dal iii secolo a.c., che è stata imitata (riprodotta) anche in diversi centri di consumo. di degrassante sabbioso sia per distribuzione dimensionale (prevalenza di sabbia molto fine e fine) che per addensamento (10÷20%) e composizione, con predominanza dei granuli subangolosi di quarzo monocristallino sui microfossili a guscio calcareo (o dei pori da impronta e dei grumi micritici da essi derivati) e piccole quantità di granuli di selce, quarzarenite e feldspato. d’altra parte, è possibile osservare una notevole somiglianza, sempre in termini sia tessiturali che composizionali, tra l’impasto delle coppe iato k480 e le argille della formazione terravecchia. infatti, dal confronto incrociato emergono un addensamento medio intorno al 15% del degrassante sabbioso con dimensione in grande maggioranza molto fine. la componente silicoclastica risulta prevalere decisamente su quella carbonatica. in quantità relativamente subordinata ma in maniera caratterizzante sono presenti piccole quantità di mica, k-feldspato e plagioclasio. ulteriori ed ancor più convincenti conferme possono essere ricavate dal confronto chimico degli stessi gruppi di campioni ceramici con le materie prime oggetto di studio disponibili in loco. già ricorrendo a semplici diagrammi binari che mettono a confronto i rapporti di concentrazione degli ossidi di alcuni elementi maggiori particolarmente caratterizzanti, cao, al2o3, k2o, na2o (fig. 9) si può chiaramente constatare la buona corrispondenza tra le argille mioceniche della formazione terravecchia e le coppe iato k480; invece, sia le imitazioni locali di campana a che le mattonelle maiolicate mostrano una discreta affinità con le argille pleistoceniche (argille di ficarazzi). la dispersione che si nota in quest’ultimo caso potrebbe essere interpretata ipotizzando il ricorso, da parte dei ceramisti, a trattamenti preliminari della materia prima (dimagrimento nel caso di sfruttamento dei banchi di argilla più plastici). inoltre, nel caso delle mattonelle per pavimentazione, l’utilizzo di un impasto più sabbioso potrebbe essere stato dettato da una scelta tecnica consapevole del ceramista. comunque, è noto, ed è stato confermato in questo studio, che le argille di ficarazzi sono di per se caratterizzate da oscillazioni composizionali non trascurabili, legate principalmente al rapporto di abbondanza tra sabbia fossilifera e componente silico-clastica (cipolla, 1931). un’ulteriore e definitiva conferma dell’utilizzo di materie prime diverse tra quelle presenti nel territorio, nel caso delle classi ceramiche sopra discusse, può essere ottenuta ricorrendo ad un ben noto metodo di analisi statistica multivariata (analisi discriminante lineare lda), i cui risultati sono mostrati in figura 10. infatti, nello spazio bidimensionale rappresentato dalle prime due funzioni discriminanti (d1 e d2) le argille del flysch numidico costituiscono un gruppo abbastanza omogeneo e, comunque, ben distinto e separato dai reperti ceramici e dalle altre argille. al contrario, le argille varicolori, pur non avendo niente in comune con 294 fig. 9 confronto chimico tra le argille di ficarazzi e le argille della formazione terravecchia con alcune tipologie ceramiche prodotte (in varie epoche) nell’area oggetto di studio. chemical relationships between the ficarazzi and terravecchia clayey’s formations and some classes of ceramic artefacts which were produced (in various periods) in the same area. g. montana et al. i reperti ceramici usati per il confronto, possiedono una varianza interna (within-group variance) tale da non poter essere considerate come gruppo. infine, è molto importante sottolineare che le argille della formazione terravecchia ricadono nello stesso intorno composizionale delle coppe iato e le argille di ficarazzi (fig. 10) si associano, sebbene con un livello di dispersione maggiore, sia alle mattonelle da pavimentazione che alle imitazioni locali di forme in campana a. 5. considerazioni conclusive i risultati sopra esposti e discussi apportano un contributo alla conoscenza delle materie prime argillose che, nei secoli passati, sono state sfruttate per la produzione di manufatti ceramici nella sicilia nord-occidentale. la ricerca parte dalla puntuale collocazione dei depositi oggetto di interesse nel quadro geologico e stratigrafico del territorio sopraccitato, aspetto sul quale è stato riposto un adeguato impegno. dai dati ricavati dalle analisi dei campioni prelevati dalle formazioni argillose oggetto di studio è possibile concludere che in base alle caratteristiche di distribuzione granulometrica, di composizione mineralogica e chimica oltre che per le proprietà di plasticità, ritiro lineare e colore dopo essiccamento e cottura, i materiali, meglio rispondenti alle qualità specifiche richieste per la produzione di forme vascolari di varia dimensione, ceramica fine e laterizi di qualità sono quelle afferenti alla formazione terravecchia ed alle argille di ficarazzi. questi risultati rafforzano quanto già poteva essere considerato più che verosimile dalle indagini archeologiche ed archeometriche recentemente effettuate sul territorio. già in passato, infatti, la sapienza empirica degli artigiani locali aveva raggiunto un livello tale da selezionare, a seconda della destinazione d’uso del manufatto, le materie prime più idonee. questo il più delle volte accadeva senza la necessità di correggere gli impasti. in altri casi le argille erano dimagrite con sabbia, oppure, ricorrendo ad opportune miscele tra varie qualità di argilla. le evidenze derivabili dai confronti esposti nel paragrafo precedente corroborano quanto appena affermato. in particolare, nel caso delle argille di ficarazzi, viene messo in evidenza anche un utilizzo eccezionalmente stabile nel tempo, anche se forzatamente circoscritto al solo agro palermitano: dalle fornaci di solunto dove si produssero anfore e ceramica da mensa o dispensa dall’età arcaica sino al periodo ellenistico-romano, a quelle dell’acqua dei corsari che si distinsero dal xvi secolo per la manifattura di mattoni per pavimentazione di ottima qualità (anche in maiolica). di contro, i materiali prelevati dal flysch numidico e dalle argille varicolori hanno mostrato, nella maggior parte dei casi, caratteristiche non propriamente idonee alla manifattura di ceramica di accettabile qualità, a causa di un assortimento granulometrico assai variabile e in genere non bilanciato, della presenza di minerali argillosi a reticolo espandibile nella frazione inferiore a 2 µm, e di un contenuto in cao il più delle volte troppo basso per garantire un sufficiente livello di vetrificazione alle temperature comunemente raggiunte nelle fornaci tradizionali (in genere inferiori o di poco superiori ai 1000°c). pertanto, l’utilizzo di queste argille dovrebbe essere stato, realisticamente, limitato e piuttosto episodico, di scarso interesse archeologico o storico-artistico e, soprattutto, circoscritto a tipologie di manufatti meno pregiate, quali laterizi (mattoni da costruzione e tegole) o, al più, vasellame grezzo ad impasto refrattario (qualora abbondantemente dimagrite con sabbia silicatica) che necessita di temperature di cottura più basse. e’ doveroso sottolineare che i risultati esposti in questa sede costituiscono solo la prima fase di una ricerca molto più vasta. essa è ancora in piena fase di sviluppo ed ha la finalità di costruire un’ampia quanto affidabile base di confronto per identificare e caratterizzare i numerosi centri di manifattura ceramica che hanno contribuito ad arricchire il patrimonio culturale siciliano. una ricerca del genere può avere, come preliminarmente dimostrato nei paragrafi precedenti, delle importanti ricadute nella soluzione di problematiche archeologiche e storiche, permettendo di acquisire nuovi criteri oggettivi per la valutazione della diffusione delle produzioni ceramiche locali, sia in ambito intrainsulare che extrainsulare, con la possibilità di valutare le attività sociali ed economiche dei singoli insediamenti, i loro livelli di evoluzione tecnologica e lo sviluppo nel corso dei secoli. 295 fig. 10 analisi discriminante di tutte le argille studiate e dei reperti ceramici di produzione locale, effettuata assumendo 4 gruppi: argille del flysch numidico; argille varicolori; argille della formazione terravecchia e coppe iato k-480; argille di ficarazzi, ceramica a vernice nera (imitazioni locali di forme in campana a), mattonelle da pavimentazione (xvi-xix secolo). discriminant analysis of the examined clay data set and of local ceramic artefacts, assuming four groups: flysch numidico (clays); argille varicolori (clays); terravecchia formation (clays and iato k-480 archaic cups); ficarazzi formation (clays, hellenistic black gloss plates and bowls and floor tiles of the xvi-xix centuries). definizione composizionale delle “argille ceramiche” ... bibliografia b. accordi (1958) il flysch oligocenico-aquitaniano dei monti nebrodi. eclogae geol. helvetiae, 51, 827. r. alaimo & g. montana (2003) scienza e archeologia: le analisi archeometriche. in “pantellerian ware. archeologia subacquea e ceramiche da fuoco a pantelleria”. s. santoro bianchi, g. guiducci, s. tusa. 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(1955) summary of “concerning same additional aids in studyng sedimentary formation” by m. s. shvetsov. journal of sedimentary petrology 25(3), pp. 229-234. tu c k e r m. e. (1981) sedimentary petrology: an introduction. blackwell scientific pubblicatio, oxford. vassallo s. (1996) coppe iato k-480: tipologia e diffusione. quaderni del museo archeologico regionale “antonio salinas”, 2. 297 ms. ricevuto il 20 febbraio 2006 testo definitivo ricevuto il 31 ottobre 2006 ms. received: february 20, 2006 final text received: october 310, 2006 definizione composizionale delle “argille ceramiche” ... imp.codici codici di nomenclatura stratigrafica i codici di nomenclatura stratigrafica negli ultimi cinquant'anni maria bianca cita abstract: m. b. cita, the codes or guides of stratigraphic nomenclature in the last fifty years. the first italian code of stratigraphic nomenclature was published in 1968 by the geological survey of italy. co-authored by a. azzaroli and m.b. cita with the collaboration of r. selli, it was realized under the auspices of the “comitato geologico” chaired by a.desio. simple, pragmatic, concise, it was inspired by the international guide authored by the chair of the international subcommission on stratigraphic classification (issc) h.d. hedberg, to be published in 1976. the very rapid development of stratigraphy in the last thirty years with the introduction of new methodologies, an integrated approach to chronocorrelation and the availability of an immense data set deriving from the scientific exploration of the oceans and of remote areas of our planet requires updates and implementations of the guides. the italian commission on stratigraphy, in collaboration with the geological survey, prepared a new version, published in 2003. a new version of the international guide is also under preparation, with a bottom up approach involving specialists of the various subdisciplines currently used in stratigraphy. parole chiave: nomenclatura stratigrafica, guide, codici. keyword : stratigraphic nomenclature, guides, codes. il quaternario italian journal of quaternary sciences 21(1a), 2008 7-8 l'idea di codificare la nomenclatura stratigrafica in modo chiaro, pragmatico e universale si è sviluppata verso la metà del millenovecento negli stati uniti d'america ad opera di hollis d.hedberg, che veniva dall'esplorazione petrolifera e fu per decenni professore di stratigrafia all'università di princeton. a lui si deve la creazione prima del nacsn (north american commission on stratigraphic nomenclature) nel 1950 e dell'international committee on stratigraphic classification (nel 1952) prima ancora che fosse costituita l'unione internazionale delle scienze geologiche (iugs). prima di allora la stratigrafia, sviluppatasi essenzialmente in europa con le forti scuole inglese (vedi schema di lyell 1875 nel logo di questo workshop), francese e tedesca, procedeva per trattati e autori, con qualche influenza esercitata dai congressi geologici internazionali, da quando essi iniziarono ad essere indetti. l'italia non aveva scuole sue proprie a causa della parcellizzazione politica. nell'italia settentrionale si sente l'influenza delle scuole francese e austriaca. in questa situazione mancava un “controllo di qualità” sui prodotti e si faceva a gara nell'istituire nuovi piani geologici mescolando spesso anche inavvertitamente caratteri litologici e cronologici e con scarsa conoscenza del potenziale di correlazione delle faune fossili. hedberg impiegò più di vent'anni e molte decine di circolari distribuite ai numerosi membri della issc (a quei tempi le comunicazioni erano molto più lente, difficili e costose di quanto lo siano oggi) per pubblicare la prima guida internazionale alla classificazione stratigrafica (hedberg, 1976). in essa viene chiaramente proposta la identificazione di diversi tipi di unità stratigrafiche: litostratigrafiche, biostratigrafiche e cronostratigrafiche e vengono definite le procedure per la loro validazione. si tratta di un approccio semplice e pragmatico, che ha dovuto superare molte difficoltà per essere accettato in diversi paesi, ma che alla fine è stato largamente adottato. prima della pubblicazione del volume da parte di una compagnia privata (hedberg, 1976, john wiley & sons, new york) diverse parti e/o capitoli erano stati stampati su riviste internazionali. la stessa rivista italiana di paleontologia e stratigrafia aveva tradotto le parti essenziali dell'opera nel 1962. quando negli anni sessanta del secolo scorso venne approvata la legge sullo per il completamento della carta geologica d'italia da parte del servizio geologico, con la partecipazione di molte sedi universitarie, il comitato geologico, presieduto da ardito desio, nominò un a commissione italiana di stratigrafia e affidò ad augusto azzaroli e maria bianca cita l'incarico di redigere un codice italiano di nomenclatura stratigrafica nel quale fossero indicate le procedure per la distinzione delle diverse unità stratigrafiche da utilizzare nelle nuove carte (azzaroli & cita, 1968). questo codice italiano uscì dunque diversi anni prima di quello di hedberg, al quale era ispirato. accanto a questa iniziativa, si procedette alla pubblicazione di una serie di fascicoli illustrativi delle diverse formazioni (unità litostratigrafiche) riconosciute in italia. edizioni successive della guida internazionale furono pubblicate da salvador (1994) e da murphy e 8 maria bianca cita salvador (1999). la prima, pubblicata dalla società geologica americana e dall'agi, è sostanzialmente una riproduzione di quella di hedberg con l'aggiunta di due capitoli: uno sulla stratigrafia paleomagnetica, molto primitivo, e uno sulle unità a limiti inconformi, assai discutibile e di difficile applicazione. la seconda è una versione abbreviata, pubblicata sull'organo ufficiale dell'iugs episodes. non è il caso di parlare qui adesso delle numerose guide nazionali, pubblicate in diversi paesi e in diverse lingue. ma ritornando all'italia e ai nostri problemi di classificazione stratigrafica, una nuova edizione aggiornata della guida è stata redatta da daniela germani e lucia angiolini, a cura della rinnovata commissione italiana di stratigrafia e con la supervisione della sottoscritta. il progetto è stato completato nell'ambito di una serie di accordi di programma e di contratti della durata complessiva di sette anni stipulati fra il servizio geologico e il cnr, o l'università di firenze, o l'istituto cnr di pisa. l'iniziativa era partita dall'ultimo comitato 05 del cnr presieduto da piero manetti, che era il contraente. fra i prodotti di questa iniziativa, oltre alla guida (ge r m a n i & an g i o l i n i, 2003) pubblicata sul quaderno serie iii, n. 9, vi sono anche sette fascicoli del quaderno n. 7 della stessa serie, dedicati all'illustrazione delle formazioni validate e di quelle non validate dalla commissione italiana di stratigrafia, nonché dei nomi tradizionali. in campo internazionale infine è iniziato un nuovo progetto nell'ambito della issc (international subcommission on stratigraphic classification), che a partire dal 2003 è presieduta dalla sottoscritta. il primo workshop della issc si è tenuto a firenze nal 2004, nell'ultima giornata del congresso geologico internazionale. in quella sede si è deciso di seguire un nuovo approccio bottom up invece di top down. infatti la stratigrafia ha avuto tali e tanti sviluppi negli ultimi trent'anni, sviluppando nuove metodiche di ricerca e accumulando una mole incredibile di dati provenienti dalle perforazioni oceaniche e da altri importanti progetti di ricerca da rendere indispensabile un aggiornamento della guida e da consigliare di suddividere la responsabilità fra i migliori specialisti del momento, siano o non siano essi membri della sottocommissione. si tratta di un progetto molto ambizioso e difficile, che darà luogo a un workshop intitolato new developments in stratigraphic classification al congresso geologico internazionale di oslo 2008. tutti gli stratigrafi italiani interessati all'argomento sono invitati a prendervi parte (hps-12 e wss-11). i primi prodotti dell'iniziativa sono appena usciti sulla rivista internazionale newsletters on stratigraphy: si tratta di un articolo introduttivo (cita, 2006) e di un saggio sulla ciclostratigrafia (strasser et al, 2006). bibliografia anonimo (1962) codice di nomenclatura stratigrafica secondo i nord-americani. rivista italiana di paleontologia e stratigrafia, 68(1), pp. 115-148. azzaroli a. & cita m.b. (1968) codice italiano di nomenclatura stratigrafica. boll. serv. geol. it., v. 89, pp. 1-22. cita m.b. (2006) new developments in stratigraphic classification. a project of the international subcommission on stratigraphic classification issc. newsletter on stratigraphy, v. 42(2), pp. 69-74. germani d. & angiolini l (2003) guida italiana alla classificazione e terminologia stratigrafica. apat, dipartimento per la difesa del suolo, quaderni serie iii, n. 9, pp. 1-155. hedberg h. (ed.)(1976) international stratigraphic guide. a guide to stratigraphic classification, terminology and procedure. pp. 1-200. john wiley & sons. new york. lyell c. (1875) principles of geology. xii edition murphy m.a. & salvador a. (1999) international stratigraphic guide an abridged version. episodes, v. 22, pp. 255-271. salvador a. (ed.)(1994) international stratigraphic guide. second edition. pp. 1-214. geol. soc. of america. s t r a s s e r a., h i l g e n f.j. & heckel p.h. (2006) cyclostratigraphy concepts, definitions, and applications. newsletter on stratigraphy, v. 42(2), pp. 75-114. ms. ricevuto il 2 aprile 2008 testo definitivo ricevuto il 17 aprile 2008 ms. received: april 2, 2008 final text received: april 17, 2008 imp.gordini& dinamica morfologica del litorale del delta del fiume tagliamento (adriatico settentrionale) in relazione ai possibili interventi di ripascimento emiliano gordini1, ruggero marocco2 & riccardo ramella1 1 istituto nazionale di oceanografia e di geofisica sperimentale ogs, trieste. (e-mail : egordini @ ogs.trieste.it; rramella @ ogs.trieste.it) 2 dipartimento di scienze geologiche, ambientali e marine, università degli studi di trieste. (e-mai : marocco @ units.it). riassunto: gordini e., marocco r., ramella r., dinamica morfologica del litorale del delta del fiume tagliamento (adriatico settentrionale) in relazione ai possibili interventi di ripascimento. (it issn 0394-3356, 2006). l’analisi morfodinamica delle spiagge del delta del f. tagliamento, dove insistono due delle località balneari più importanti dell’alto adriatico, ha messo in evidenza l’esistenza di tratti di litorale soggetti ad endemica erosione, altri in progressione ed altri ancora tendenzialmente stabili. rilievi topo-batimetrici di 66 profili perpendicolari alla spiaggia emersa, intertidale e sottomarina, eseguiti su scala annuale nel 2002-2003 (da un periodo estivo di ripascimento della spiaggia ciclo estivo o swale ad uno di erosione invernale ciclo invernale o storm) e il loro confronto con le risultanze dei studi precedenti hanno permesso di definire che nell’ambito della spiaggia sottomarina le variazioni stagionali e quelle pluriennali sono minime ad eccezione dei tratti in corrispondenza delle aree di foce e di bocca lagunare. qui si assiste ad un incremento dei fondali che beneficiano della deflessione del trasporto lungo riva a causa del pennello liquido dei flussi lagunari e fluviali. nell’area più dinamica della spiaggia sottomarina (zona delle barre e dei truogoli), poi, le variazioni sono determinate essenzialmente da semplici traslazioni delle barre verso terra e verso mare, senza perdite o guadagni volumetrici. diversa è invece la situazione lungo le spiagge intertidali ed emerse dove le variazioni sono sensibili e determinate a volte da cause naturali (scarsità di alimentazione lungo riva, incidenza del moto ondoso, ecc) ma anche dallo stratificarsi nel tempo di opere di difesa marittima diverse, costruite per finalità più disparate e oggi non completamente funzionanti. la situazione più drammatica è stata riscontrata nell’area fociale del tagliamento, dove gran parte delle sponde e dei tratti di spiaggia apicali sono soggetti ad intensa erosione, mentre complessivamente, le spiagge sottomarine immediatamente adiacenti sono in progressione (con un incremento di ca. 0,085 m3/m2). le aree in accumulo risultano essere particolarmente localizzate al centro del fronte deltizio e al suo lato oriente, poco a se dalla testata di un pennello di sbarramento. l’analisi a medio e lungo termine delle variazioni volumetriche in quest’area, risultanti dal confronto con rilievi precedenti (brambati 1987), eseguiti nel 1969 e nel 1985, hanno permesso di definire che dopo una prima fase di accrescimento delle spiagge intertidali ed emerse ed un approfondimento di quelle sottomarine (1969-1985) si è passati ad una situazione diametralmente opposta (1985-2002) che permane fino ad oggidì. in questa condizione, data la necessità di reperire sedimenti per un urgente ripascimento delle spiagge in erosione (circa 50.000 m3 anno) e di garantire il passo marittimo della foce, si ritiene che oltre alla porzione esterna dell’alveo fluviale che deve essere risagomato e approfondito (68.000 m3 e 166.000 m3 per raggiungere rispettivamente le profondità di 2,5 e 3,5 m ed una larghezza di 100-150 m) una parte di questo materiale (circa 90.000 m3) può essere prelevato dalle aree in accumulo rilevate da questo studio che oltre ad essere poste in vicinanza della foce, sono soggette a ricarica annuale. abstract: gordini e., marocco r., ramella r., morphological dynamics of the littoral zone of the tagliamento river delta (northern adriatic sea) related to eventual nourishment works. (it issn 0394-3356,2006). the morphodynamic analysis of the tagliamento river delta beaches, where two of the most important holiday sites of the upper adriatic sea are located, revealed some areas undergoing endemic erosion, some of which are presently under accretion, and others that appear to be stable. sixtysix topographic and bathymetric profiles orthogonal to the emerged, inter-tidal and submerged portions of the beaches were obtained during 2002 and 2003. comparison to results from earlier studies showed that seasonal and multiyear variations in the submerged areas are very low, except for the zones located in correspondence to the river mouth and the tidal inlet. here, the thickness of the sea floor sediment cover increases due to the deviation of the alongshore sediment transport as a consequence of both the tidal and fluvial outflows from the lagoon. in the most dynamic areas of the submerged beaches (bars and troughs), the sediment thickness variations are mainly represented by the outward and inward movements of the bars without net sediment volume losses or gains. a different situation has been identified in correspondence to the inter-tidal and emerged zones, where the variations are more conspicuous and are due not only to natural phenomena (limited alongshore feeding, waves etc.) but also to several coastal protection structures (constructed in the past for different purposes) that are not very effective. the worst situation has been found at the tagliamento river mouth where most of the river levees and the apical beach areas are undergoing intense erosion. instead, the adjacent submerged beaches are in general presently accreting (a global increase of 490.000 m3). the areas characterized by sediment accretion are mainly located in the central sector of the delta front and at its eastern side, southeast of a groin. the volumetric variations in the area have been analyzed over both short and long time-scales, and the resulting information has been confronted with those obtained from previous studies carried out in 1969 and in 1985 (brambati, 1987). this defined that, after a first accretion phase of the inter-tidal and exposed parts and of a deepening of the submerged portions of the beaches (1969 -1985), a completely different regime set in (1985-2002) which appears to characterize the present situation. a sediment supply in the order of about 50.000 m3/yr is urgently necessary to replenish the eroded beaches. sediment could be extracted from the river fan which presently has to be re-shaped and deepened for safe navigation (68.000 m3 or 166.000 m3 depending on whether a water depth of 2,5 m or 3,5 m is required, and a width roughly ranging from 100 m to 150 m). part of this material (90.000 m3) could also be obtained from the accretion areas, characterized currently by annual feedings, that were identified in the present study. parole chiave: dinamica costiera, ripascimento, delta fiume tagliamento, adriatico settentrionale, italia. keywords: coastal dynamics, nourishment, delta tagliamento river, northern adriatic sea, italy. il quaternario italian journal of quaternary sciences 19(1), 2006 45-65 46 e. gordini, r. marocco & r. ramella 1. introduzione oggigiorno diventa sempre più pressante individuare cave di prestito di sedimenti sabbiosi o ghiaiosi per cercare di porre rimedio alla ormai endemica erosione dei litorali, provocata a volte da cause naturali, ma anche e soprattutto dall’alterazione degli equilibri costieri da parte dell’uomo. in questa problematica, dettata anche da criteri d’estrema urgenza, rivestono particolare rilevanza gli studi di dinamica costiera finalizzati alla definizione delle modalità ottimali d’intervento, fermo restando la salvaguardia paesaggistica ed estetica dell’ambiente costiero. per far ciò spesso ci si avvale della tecnica di ripascimento artificiale delle spiagge che prevede il prelievo di opportuni accumuli sabbiosi in mare, rappresentati quasi sempre dalle sabbie di piattaforma, dalle barre di foce e dei delta di bocca lagunare e, buon ultimo, da cave a terra. esiste oggi una nutrita letteratura in merito che si rifà ai primi interventi nelle aree liguri, toscane, laziali e venete (cfr. ad esempio, capobianco et al., 1999), sino alle recenti sistemazioni costiere che ormai ricoprono gran parte del territorio nazionale con una mobilitazione di volumi di materiale per diversi milioni di m3 (di cui ca. 6 milioni per i soli litorali di pellestrina e cavallino nel veneto; de girolamo et al., 1999). fatte salve tutte le valutazioni sugli impatti ambientali che tali operazioni comportano, e l’annoso problema del mantenimento di questi materiali con opere di difesa “morbide” o “pesanti” o alla loro ricarica periodica, il provvigionamento di questi materiali può essere ricercato, come detto, a mare, a breve o lunga distanza dalla costa, oppure nell’ambito della fascia litorale stessa, attingendo anche a spiagge emerse in eccessivo accrescimento o ai passi marittimi che abbisognano di continue escavazioni. va rimarcato che in questo contesto non vanno assolutamente toccati gli accumuli eolici costieri che sono stati recentemente molto compromessi a seguito delle estrazioni e sbancamenti eseguiti a scopi edilizi che hanno determinato la costruzione di agglomerati urbani a nastro sull’intera linea di costa. le dune, che oltretutto fanno parte integrante e fissano la parte alta della spiaggia, vanno pertanto tutelate, preservate e possibilmente accresciute, non solo per il loro naturale valore paesaggistico ed ambientale, ma anche perché rimangono, a volte, l’ultimo baluardo costiero per contrapporsi alle mareggiate più violente e, a meso o macro scala temporale, alla paventata ingressione marina (prossima ventura). d’altro verso le sabbie di piattaforma dell’alto adriatico (che si ubicano mediamente dai 13 ai 25 m di profondità) rappresentano serbatoi molto estesi, quasi sempre poco potenti e a scarso rinnovo, poiché ereditati e rielaborati dall’ingressione marina quaternaria e limitatamente toccati dalle ondazioni attuali. ospitano inoltre una ricca popolazione di molluschi eduli e diffusi affioramenti rocciosi (gordini et al., 2004) che sono una delle ricchezze più ambite dai pescatori dell’intero comparto adriatico e pertanto difficilmente utilizzabili a questi fini senza innescare conflitti sociali. più interessanti, allora, rimangono i potenziali serbatoi sotto costa che oltre ad avere il pregio della loro vicinanza dal litorale, sono di per sé serbatoi rinnovabili in quanto ricaricati dal “nastro trasportatore litorale” e per questo, spesso scavati per mantenere officiosi i passi marittimi del retroterra. va da sé che questi serbatoi rappresentano almeno in casi di normale ripristino e conservazione di un litorale una delle soluzioni ideali, anche perché non modificano il complessivo bilancio volumetrico dell’unità fisiografica del paraggio. anche questo intervento, comunque, deve essere valutato attentamente in funzione della previsione dei tempi di ricarica delle cave di prestito e della quantità-qualità del materiale prelevabile. si rimarca che l’escavazione in queste aree comporta almeno teoricamente un duplice beneficio; la ricostruzione delle spiagge, da un lato, e la garanzia dell’accesso ai porti turistici, dall’altro, infrastrutture queste che rappresentano oggi una componente essenziale nell’offerta turistica di una località balneare. il presente studio intende investigare nell’ambito di un sistema complesso come quello del delta del f. tagliamento che ospita due tra le località turistiche più rinomate dell’alto adriatico (lignano nel friuli venezia giulia e bibione nel veneto), le potenzialità a breve e medio termine dell’utilizzo dei serbatoi naturali di depositi rappresentati dalla foce e dalle bocche lagunari per intervenire con ripascimenti artificiali sui tratti di litorale in forte erosione. queste possibili strategie d’intervento saranno adottate solamente dopo la definizione delle caratteristiche morfodinamiche del paraggio e il contesto evolutivo dei fondali di spiaggia (oggetto di questo studio) e della caratterizzazione sedimentologica e chimico-ambientale dei depositi sabbiosi da utilizzare, sancita dalle leggi vigenti (legge 179 del 2003). la scelta del delta del tagliamento come area campione per questa analisi è stata determinata in primo luogo dalla richiesta da parte delle amministrazioni locali di inquadrare sotto questa problematica le loro zone di competenza e in secondo luogo dalla possibilità di confrontare i risultati dei rilievi morfologici attuali con le risultanze di una nutrita serie di studi precedenti (vedi soprattutto zu n i c a 1971, br a m b a t i 1987 e più recentemente, fontolan 2004) che permettono una visione panoramica e uno spessore cronologico delle fenomenologie dinamico-costiere rilevate nell’arco di un anno e in condizioni deposizionali erosive differenti (swale storm). 2. il delta del f. tagliamento l’area costiera oggetto dello studio è incentrata sulle coste basse e sabbiose del delta bilobato del tagliamento che rappresenta uno dei sistemi fluviali più importanti dell’italia settentrionale. si ubica geograficamente a cavallo della regione friuli venezia giulia (est) e veneto (ovest) tra i golfi di trieste e quello di venezia; il suo limite meridionale viene convenzionalmente posto lungo la batimetrica 8, approssimativamente lungo una rotta parallela alla costa ad una distanza di circa 3 km da essa. il litorale espone le sue spiagge a diversi regimi di vento e conseguentemente di moto ondoso. il suo regime anemometrico è governato dallo spirare dei venti del i° quadrante e soprattutto di quello di bora (ene, prevalentemente nella stagione invernale e autunnale). per quanto concerne i venti meridionali, lo scirocco, dopo la bora, è il vento che può raggiungere le massime velocità nel paraggio; segue il libeccio, che spira da so, con frequenza di poco inferiore a quella dello scirocco (essenzialmente dalla primavera all’estate). nel periodo estivo l’area è inoltre interessata da venti settentrionali prevalentemente a carattere diurno provenienti dal iv° quadrante (termiche estive). il mare regnante risulta essere quello di bora, che risente di considerevoli rifrazioni prima di giungere sulla battigia, mentre quello dominante è di scirocco, con in subordine il mare di libeccio (c a t a n i , m a r o c c o , 1976; brambati, 1987). le maree sono tra le più ampie del mediterraneo. in situazione di sizigia (onde semidiurne) raggiungono un’escursione media a trieste di 86 cm (100 cm a venezia); in quadratura (onde diurne) un’escursione media di 22 cm (20 cm a venezia). casi eccezionali di acqua alta, hanno fatto registrare valori di 130 cm con valori estremi attorno ai 200 cm (marocco, pessina, 2000). la circolazione media del bacino è ciclonica con corrente ascendente lungo le coste croate e discendente lungo quelle italiane. studi condotti sull’evoluzione recente della fascia costiera hanno dimostrato che il delta attuale del tagliamento si è formato circa 2.000 anni fa a seguito di una diversione orientale del fiume che ha disseccato la paleolaguna di marano. la formazione del delta non si è realizzata con una progradazione graduale, ma con rapidi accrescimenti intervallati da fasi erosive e di stabilità (marocco, 1988; 1989; 1991). dalla cartografia storica analizzata con grande perizia da zunica (1971) emerge che dal 1644 al 1868 il delta ha subito profonde modifiche, in parte determinate da fattori naturali e dal regime meteo-marino del momento e in parte dall’uomo che ha modificato profondamente il territorio con opere di bonifica, tombamenti, arginature e continue regimazioni fluviali. per quanto attiene alla forma bialare del delta, il confronto delle carte prese in esame mette in risalto che le maggiori modificazioni si sono avute sull’ala destra del delta. segnatamente da una conformazione tozza e convessa verso mare del litorale (situazione del 1822) si passa, in un lasso di soli 46 anni, ad una accentuata concavità, particolarmente evidente nella sua porzione centro-occidentale a testimonianza del succedersi di eventi erosivi. si avverte anche una sensibile migrazione dell’asta terminale del fiume, con una prima e modesta rotazione verso levante, seguita, successivamente, da traslazioni verso ponente, tendenza, questa, che viene mantenuta anche attualmente. l’accrescimento della foce ha dunque mantenuto nel tempo un asse di direzione so. lo stesso autore specifica, inoltre, che il massimo arretramento dell’ala deltizia si è realizzato in un brevissimo periodo dal 1822 al 1833, seguito da graduali avanzamenti che nel 1868 riportano il litorale alla condizione di partenza, per poi superarla nel 1903. nello stesso intervallo temporale il rimanente tratto di litorale risulta sensibilmente più stabile, mentre fa registrare un forte incremento alla fine del secolo. dalle evidenze sopra esposte, considerate dovutamente le incertezze del metodo, emerge che il delta non ha avuto un ciclo evolutivo continuo nell’arco di tempo considerato, ma un’intermittenza di fasi particolarmente evidenti nell’ala destra. l’analisi delle varie edizioni delle tavolette i.g.m. (dal 1937 al 1951) confermano gli andamenti della costa dedotti dalle carte più antiche con una maggiore dinamicità dell’ala destra rispetto a quella sinistra, dove continuano periodi di cospicuo ripascimento, intervallati da altri di intensa attività erosiva. le diverse levate rendono particolarmente manifesto il meccanismo di 47dinamica morfologica del litorale ... accrescimento del delta che si attua con un progressivo saldamento di scanni sabbiosi alla battigia e la migrazione delle barre sottomarine sempre verso ovest, che vanno ad implementare quelle del delta inlet di punta baseleghe. anche brambati (1987), sulla base del confronto delle linee di riva riportate nei rilievi del 1891, 1978 e 1985, conferma l’ evoluzione dell’ala sinistra del tagliamento sottolineando l’accentuato sviluppo del lobo orientale della foce, in controtendenza all’erosione del tratto di litorale che si estende fino a lignano riviera. più ad est di questa località, fino alla bocca di lignano, risalta anche in questo caso, a livello secolare, una forte progressione della spiaggia. più recentemente, fontolan (2004) a riguardo dell’ala occidentale del delta evidenzia, riprendendo i dati di brambati, come nel 1968 per contrastare la forte erosione che, nella parte più prossima alla foce, poneva in pericolo la struttura del faro, furono costruiti tre frangiflutti in massi che, nei mesi successivi, favorirono un discreto accumulo di sabbie (brambati, 1970). sempre l’autore rimarca come la tendenza evolutiva del litorale sia rappresentata da una marcata fase erosiva del settore prossimo alla foce, il cui materiale, seguendo il verso della corrente di deriva principale, subisce un trasporto prevalente verso ovest. una parte di esso va a depositarsi nella porzione centrale del lobo occidentale deltizio, esattamente sul fronte della parte maggiormente urbanizzata: l’altra concorre all’accrescimento verso occidente del sistema bocca di porto baseleghe. significativa risulta anche la parziale distruzione dell’apparato dunare in corrispondenza della lama di revelino e di punta faro, anche se recentemente difeso da frangiflutti in continua risagomatura e prolungamento. anche il fronte delle dune litorali, fissato negli anni ’ 90 da sacchi di geotessile sovrapposti, risulta oggi fortemente compromesso, al di là delle viminate e dei sacconi di sabbia posti a loro difesa. in questa area la linea di riva ha subito un forte arretramento, con la completa scomparsa della spiaggia emersa, l’erosione del piede dell’avanduna e una perdita volumetrica stimata in 1,3 m3/m/anno (1968-88, da fontolan, 2004) sui fondali marini antistanti. numerosi sono i lavori sedimentologici eseguiti sui fondali antistanti il delta (brambati, venzo, 1967; catani et al., 1978; brambati et al., 1979; brambati et al., 1982; brambati, 1987). in estrema sintesi, i sedimenti che contraddistinguono questo tratto di litorale sono costituiti da sabbie medio fini, unimodali e ben classate dalla battigia fino alla profondità di 2-3 m e da depositi bimodali e moderatamente classati, costituiti da sabbie fini variamente mescolate a peliti, oltre questa profondità. quest’ultime diventano preponderanti al largo della foce e sui fondali oltre i 7 m. la dinamica del trasporto delle sabbie avviene per sospensione gradata (seguendo passega, 1964) e per saltazione secondo le metodiche di vischer (1969): quella delle peliti per sospensione più o meno uniforme. la dispersione dei contributi terrigeni fluviali avviene in modo diverso a seconda della granulometria: il pattern dei sedimenti sabbiosi più grossi evidenzia una movimentazione in un’area ristretta, disposta simmetricamente alla foce (con una maggiore tendenza verso ovest), mentre quello dei sedimenti più fini palesa una dispersione a distanze maggiori approssimativamente dalle batimetri48 che 6-7 in poi. risulta infine interessante osservare che, sempre secondo gli autori precedenti, il trasporto della frazione fine avviene in modo predominante al largo della isobata 7 m e comunque da est a ovest. geologicamente i depositi fronte mare rappresentano la tipica sedimentazione dei prismi costieri di h.s.t (highstend system tract) che testimoniano il massimo livello del mare raggiunto durante l’ultima trasgressione marina (marocco, 1991; gordini et al. 2002). l’intera area deltizia è stata oggetto, sin dagli anni ’60, di una intensa antropizzazione a fine urbanistico residenziale. le abitazioni sono sviluppate soprattutto a nastro nelle strette vicinanze delle spiagge e hanno comportato lo sbancamento dei rilievi dunari. l’impetuoso sviluppo urbano ha comportato anche l’insediamento di importanti poli nautici che hanno trovato luogo nelle strette vicinanze delle bocche lagunari (di lignano ad est) e di porto baseleghe (ad ovest). anche l’asta terminale del tagliamento è stata recentemente fissata dalla creazione di una marina che utilizza l’entrata del fiume come canale d’accesso. da una stima preliminare, risulta che gli attuali posti barca direttamente collegati all’attività turistica del delta (parte veneta e parte friulana) siano superiori a circa 5.000. non va inoltre dimenticato che all’interno d’ogni marina sono ospitati: cantieri nautici, officine, aree residenziali, spazi ricreativi, impianti sportivi, campi da tennis, piscine, bar e ristoranti, con un conseguente elevato impatto ambientale. in riferimento al grado di antropizzazione del litorale, in particolare durante la stagione estiva (maggiosettembre) i dati delle aziende turistiche di lignano e bibione, denunciano un’affluenza che da un calcolo approssimativo si aggira complessivamente sulle 8 milioni di presenze. in questo periodo le spiagge risultano quasi completamente occupate da circa 60.000 lettini, 31.000 ombrelloni che vengono tolti in periodo invernale per far posto a staccionate a difesa dalla deflazione eolica. 3. metodologia applicata alla definizione della spiaggia emersa, intertidale e sottomarina e processing dei dati batimetrici. sui 18 km circa di litorale che si estende sulle ali del delta sono stati eseguiti 66 profili topo batimetrici (fig. 1), con spaziatura di circa 150 200 m in corrispondenza della foce, mentre mediamente compresi tra 250 350 m nelle rimanenti aree. i profili sono stati ripetuti durante condizioni deposizionali ed erosive differenti, nello specifico, nei mesi di settembre ed ottobre 2002 e maggio e giugno 2003, al fine di evidenziare eventuali modificazioni su scala stagionale. la morfologia della spiaggia emersa e della porzione di spiaggia e. gordini, r. marocco & r. ramella fig. 1 delta del f. tagliamento: ubicazione dei profili batimetrici, dei capisaldi di riferimento e zonazione dei tratti di spiaggia intertidale e sottomarina. tagliamento river delta: location of the bathymetric profiles, fiducial points and zoning of the inter-tidal and submerged beach. 49 intertidale non coperta dai rilievi batimetrici è stata determinata con metodologia lidar1. contemporaneamente è stato eseguito anche un rilievo fotogrammetrico, condotto con camera–digitale semimetrica. la posizione planimetrica dei transetti batimetrici è stata ottenuta con dgps cinematico, in modalità continua. la strumentazione installata a bordo dell’imbarcazione è stata la seguente: • un ricevitore ashtech g12 lite dotato di decodificatore dgps landstar mkiv della thales tracs ltd per la correzione differenziale in tempo reale; • un plotter ed ecoscandaglio di navigazione lowrance lcx – 18c a doppia frequenza 200/50 khz dotato di cartografia elettronica dell’alto adriatico e funzione di registrazione e visualizzazione grafica dei profili; • un ricetrasmettitore cb 40 canali; • un computer portatile compaq presario 1200 con il compito di gestire l’acquisizione simultanea dei dati di profondità e di posizione forniti, rispettivamente, dall’ecoscandaglio e dal gps/dgps con una frequenza di un secondo. l’indagine è stata eseguita in condizioni di mare calmo, assenza di vento, con marea quasi sempre prossima alla quadratura. la velocità dell’imbarcazione è stata mantenuta costante (3,5 e 4,5 nodi). agli ecogrammi del fondo marino sono state apportate, in fase di elaborazione (postprocessing), le seguenti correzioni (fig.2): 1. il valore di offset del sensore dell’ecoscandaglio rispetto al pescaggio dell’imbarcazione; 2. taratura dello strumento per valutare le variazioni chimico fisiche della colonna d’acqua; 3. stima delle variazioni di immersione del trasduttore a seconda delle diverse velocità di navigazione; 4. ortogonalità dell’impulso acustico inviato dal trasduttore dell’ecoscandaglio rispetto il fondale marino; 5. escursione di marea astronomica-meteorica; 6. filtraggio di variazioni accidentali verticali dell’imbarcazione (onde provocate da altre imbarcazioni, ecc.). da verifiche eseguite in campo risulta che l’errore medio del rilievo batimetrico si aggira attorno ai +/7 cm. le variazioni volumetriche riscontrate dalla ripetizione dei profili in periodo invernale ed estivo sono state definite utilizzando il software matlab 6.5.1 della mathworks. il software ha permesso di passare dai due dem (digital elevation model) dei due rilievi ogs 2002 e 2003, ad una griglia a maglia quadrata che ha consentito per interpolazione lineare, il calcolo delle perdite o acquisti volumetrici dei fondali. 4. batimetria e caratteri morfologici della spiaggia i dati batimetrici sono stati processati con programma surfer version 8.0 surface mapping system della golden software, inc. le figg. 3 e 4 fotografano l’assetto bati morfologico del fondale della spiaggia intertidale e sottomarina nel maggio-giugno 2003. nella carta morfo batimetrica di fig. 4, sono ben visibili le morfologie positive (barre, dune, ecc…) del fondo marino, quelle negative (truogoli, incisioni, ecc…), a testimonianza della specifica dinamica del moto ondoso, dei flussi fluviali e delle correnti mareali lungo i delta inlet. 4.1 zonazione del litorale del delta del f. tagliamento sulla base dei risultati conseguiti è possibile eseguire una zonazione delle spiagge del delta a partire dall’area centrale ed interna alla foce del tagliamento (tratto d di fig.1). dinamica morfologica del litorale ... 1 il sistema lidar utilizzato è l’altm3033 di proprietà della helica s.r.l. e costituito da un laser operante nell’infrarosso (λ=1063 nm) che invia impulsi di luce alla frequenza di 33 khz. il sistema è stato montato solidale all’elicottero as350b2 a sua volta dotato di una piattaforma inerziale, che dispone di compensazione per le variazioni di assetto dell’aeromobile in rollio e beccheggio oltre al posizionamento dgps. l’indagine ha permesso di ottenere una densità media di punti al suolo superiore a 1,5 punti al m2. la camera digitale utilizzata per il rilievo fotogrammetrico è del tipo semimetrica rollei modello 6008 con dorso digitale phaseone modello h20. il sistema di acquisizione digitale ha una spaziatura di pixel di 9 micrometri ed è composta da 4080 x 4076 pixel con una dinamica di 48 bit. fig. 2 diagramma a blocchi del postprocessing applicato alle registrazioni del fondo marino. flow diagram of the post-processing sequence applied to the sea floor records. 50 e. gordini, r. marocco & r. ramella f ig . 3 c a rt a b a ti m e tr ic a d e lla s p ia g g ia in te rt id a le e s o tt o m a ri n a d e l d e lt a d e l f . t a g lia m e n to . r ili e vi o g s 2 0 0 3 . b at h ym e tr ic m ap o f th e in te rti d al a n d s u b m e rg e d b e ac h o f th e t ag lia m e n to r iv e r d e lt a. 2 0 0 3 o g s s u rv e ys . 51dinamica morfologica del litorale ... f ig . 4 s c h e m a m o rf o d in a m ic o -s e d im e n ta ri o d e l d e lt a d e l f . t a g lia m e n to e d e l s u o li to ra le . m o rp h o -d yn am ic a n d s e d im e n ta ry s ke tc h o f th e t ag lia m e n to r iv e r d e lt a an d o f it s lit to ra l a re a. la foce del f. tagliamento tratto d l’asta terminale del fiume, dopo un percorso meandriforme, si sviluppa su un breve tratto rettilineo (ampiezza di 150 m e profondità di 6 m circa) dove si è insediata la darsena “marina uno” e continua fino a mare, con sezione d’alveo molto simmetrica e classica barra di foce. sul tratto centrale dell’alveo sono presenti campi di dune subacquee (sensu, ashley et al., 1990; fontolan et al., 2000) a profilo asimmetrico, sviluppate secondo il flusso uscente, che divengono simmetriche verso lo sbocco a mare; qui, la piana sommersa viene definita da una vasta area semicircolare, a debole pendenza (da 1,0 a 1,7 ‰) incisa dal canale di foce, in parte naturale e in parte scavato artificialmente per rendere accessibile l’ingresso al porto fluviale. il passaggio tra la porzione interna ed esterna della foce, è contraddistinto dalla presenza di uno sviluppato ebb-tidal delta, che si concretizza con un imponente water flow ramp che dalla profondità di 6,0 m (darsena “marina uno”) passa, ad una distanza di circa 1,3 km (verso mare), ad una profondità di 1,0 m. il fronte deltizio s’identifica con il fitto ravvicinamento delle isobate comprese tra 1,0 e 6,0 m che determina un gradino morfologico ad elevata acclività (massimo 1,3 %). questo gradino rappresenta il limite estremo delle gittate solide più grosse del tagliamento, e dunque, i più recenti depositi riconducibili al sistema hst. nel dettaglio (fig. 3 e fig 5; transetto l01lignano e b03-bibione) la piana sommersa viene contrassegnata dalla presenza di numerose bedforms, che vanno dalle canalizzazioni marginali (1,2 m), solo in parte naturali che si sviluppano al piede delle barriere frangiflutto del faro di punta tagliamento, alle barre allungare e uncinate (altezza di circa 0,2-0,5 m) oltre a numerose barre di swash lunate, alternate ad altre più irregolari (altezza 0,4-0,6 m), in continua evoluzione e trasformazione operata dal moto ondoso. queste ultime morfologie attive, conferiscono al delta una componente wave-dominated (sensu, hayes, 1980) che palesa la ridistribuzione degli apporti da parte del moto ondoso. il canale principale è bordato da barre lineari di margine (altezza variabile da 0,5 a 0,8 m) che manifestano un maggiore sviluppo al lato occidentale. l’alveo della foce è soggetto a periodiche escavazioni per assicurare l’accesso al porto “marina uno. ad esempio, nel maggio 2003 ingenti quantità di sabbia sono state prelevate al letto del canale navigabile e depositate immediatamente ad ovest dell’area di scavo. ciò ha comportato una modificazione della forma e dell’estensione del fronte deltizio e, nel dettaglio, ha innescato un riequilibrio del canale e la trasformazione della barra lineare di margine. procedendo da ovest verso est, la linea di costa assume un andamento sinuoso, caratterizzato dal naturale protendimento fociale “sostenuto”, anche, da un lungo pennello di sbarramento, realizzato nel 1963 (fig. 5; transetto l01-lignano) e, accorciato, recentemente, per favorire il by-passing dei sedimenti e la loro naturale dispersione verso est. la spiaggia emersa, completamente livellata nel periodo balneare-estivo, assume un’estensione di circa 100 m ed è delimitata, verso terra, da apparati dunari a forma di barcana con al fronte accumuli eolici minori che vengono zappati dalle mareggiate invernali; quella intertidale, risulta leggermente più estesa (ca. 120 m) con un ampio terrazzo di bassa marea (tra 1,0 e 1,5 m), con barre di swash (sensu, king c.a.m., 1972; ashley et al., 1990), e campi di barre di accrescimento con orientazione sud-ovest (fig. 5; transetto l01-lignano). la spiaggia sottomarina è contraddistinta da un brusco restringimento delle isobate poste a circa 1 km dalla foce e da una loro inflessione verso riva. segnatamente, dopo la zona sub-orizzontale sostenuta dall’opera di difesa, segue una forte acclività del fondale (passaggio dalla isobata 1,0 a quella 6,0 m in 325 m circa) su cui si insediano forme di fondo attive (barre e cordoni sottomarini), determinate dall’interazione dell’energia di trasporto fluviale con quella litorale. va sottolineato che il corpo sedimentario di questo prisma deltizio rappresenta un notevole serbatoio di materiale sabbioso, eventualmente sfruttabile per mirate operazioni di riequilibrio del litorale circostante. dopo il piede del fronte deltizio il fondale declina dolcemente con valori (ca. 2,0 ‰) che rispecchiano le pendenze dei fondali limitrofi e sono caratterizzati dalla sedimentazione di materiali fini. al lato opposto, la sponda occidentale della foce del tagliamento, oggetto in questi anni di un rapido arretramento, è stata progressivamente difesa con importanti opere marittime a mare (scogliere) e al piede delle dune (fascinate verticali, graticciate, tubi tipo longard riempiti di sabbia) che hanno trasformato radicalmente l’aspetto paesaggistico del paraggio e l’idrodinamica litorale. tutte queste opere, comunque, non hanno evitato il perdurare dei processi erosivi che esplicano la loro massima concentrazione nel tratto interno alla foce ed immediatamente ad ovest del faro di punta tagliamento. il litorale è formato da una spiaggia piatta e di modesta estensione, contraddistinta da mini tomboli collegati ai frangiflutti. nelle aree non protette si registra una repentina regressione della battigia che ha portato ad una ulteriore diminuzione della spiaggia (< di 50 m) che ora viene delimitata verso terra dalle lame tra i vecchi cordoni dunari (lama di rivelino). la spiaggia intertidale e sottomarina mostrano, nell’insieme, l’assenza o quasi del terrazzo di bassa marea e un minimo sviluppo della zona dinamica a barre e truogoli. qui la transizione dalla battigia alla spiaggia esterna avviene con un’elevata acclività, indice questo, di una profonda instabilità. al piede delle scogliere, la spiaggia sommersa è incisa da una depressione (ampia circa 100 m e profonda 1,2 1,5 m), probabilmente determinata, in analogia con situazioni analoghe personalmente riscontrate, in parte da fenomeni di riflessione del moto ondoso (fig. 5; transetto b03-bibione) e in parte, anche dalle correnti di fondo dei flussi marginali del fiume. segue verso mare, una seconda ampia piana sub-orizzontale (da 0,5-1,0 m), dove sono evidenti in posizione arretrata barre intertidali seguite da cordoni sottomarini e complessi sistemi di barre di swash, complessivamente fino a 600-800 m dalla costa. dal piede della barra più esterna, si passa quindi con un brusco cambiamento di pendenza ad un fondale sub-pianeggiante: in particolare, la base della fascia degradante verso le profondità maggiori, si colloca ad una distanza pari circa 1000 m (corrispondente a 5,0/6,0 m di profondità) con un valore medio di pendenza di 15,4 ‰ (confrontabile con quello riscontrato sull’analogo settore dell’area friulana). dalla profondità di 6,0 m fino al limite dell’area indagata (circa 3000 m dalla battigia, 11,0 m), il fondale 52 e. gordini, r. marocco & r. ramella 53dinamica morfologica del litorale ... fig. 5 alcuni esempi significativi di profili topobatimetrici riguardanti le spiagge del delta del f. tagliamento. per l’ubicazione dei profili si rimanda alla fig. 1. le quote, in metri, sono riferite al livello medio mare (l.m.m.), mentre, le progressive, sempre espresse in metri, sono riferite ai capisaldi istituiti lungo il litorale. some meaningful examples of topographic and bathymetric profiles acquired in correspondence to the beaches of the tagliamento river delta. see fig. 1 for the profiles location. the elevation expressed in meters, are referred to the medium sea level (l.m.m), whereas the distances (in meters) are referred to the fiducial points located along the coast. marino presenta andamento pressoché tabulare con minima inclinazione. litorale orientale (dalla foce del tagliamento alla bocca di lignano) tratto c alla zona prettamente di foce segue verso est, senza soluzione di continuità, una linea di riva ad andamento prevalentemente concavo, disarticolato dalla presenza di numerosi pennelli trasversali che interrompono con i classici denti di sega il suo sviluppo lineare. l’accumulo delle sabbie sul lato occidentale dei pennelli rende palese la prevalenza del trasporto lungo riva da ovest verso est. la minor influenza del trasporto regionale in senso opposto (da est verso ovest), sembra essere legata al forte sviluppo dell’ebb-tidal delta della bocca lagunare di lignano, che trattiene gran parte dei depositi e in parte flette il movimento dei sedimenti verso il largo. il bilancio sedimentario totale, comunque, rende palese che gli arrivi di sabbie da ovest non compensano adeguatamente le perdite per erosione ormai croniche di questo tratto di costa. anche la limitata estensione della spiaggia (ca. 50 m, ampiezza tra le minime dell’intero paraggio), evidenzia i regimi erosivi tuttora in atto e l’inefficacia delle opere di difesa. la spiaggia emersa è delimitata al retro da opere longitudinali aderenti per impedire l’erosione delle aree urbanizzate retrostanti, ma che possono determinare pericolose superfici riflettenti dell’onda di mareggiata. il settore di litorale manifesta una zona sub-orizzontale molto limitata (10-15 m circa) o quasi del tutto assente e ravvivata da una unica barra intertidale (talvolta assente), seguita verso mare da un truogolo che si posiziona grossomodo a breve distanza dalla testa dei pennelli (fig. 5; transetto l07-lignano). più ad oriente, il fianco orientale del conoide deltizio si inflette verso costa, determinando un rapido approfondimento del fondale anche a limitata distanza dalla battigia e in particolar modo nell’area antistante le opere di difesa. la zona a barre e truogoli presenta un’estensione di circa 140 -160 m, una o al massimo due, barre sottomarine che si sviluppano su un’area a pendenza variabile da 12,7 a 16,3 ‰ (fig. 5; transetto l15-lignano). dopo la zona dinamica, il fondale presenta tre caratteristiche fasce a diversa pendenza: la prima, della barra sottomarina più esterna (ca. 200 m dalla battigia, 3,0 m), fino a circa 500 m dalla battigia (-4,5 m), con un’acclività prossima a 4,2 ‰, una seconda, tra 500 e 900 m circa dalla riva (rispettivamente 4,5 e 5,9 m di profondità) con un’acclività superiore alla fascia precedente (7,3 ‰) e, infine, la terza fascia che si colloca ad una distanza compresa tra 900 e 1900 m circa (corrispondenti a 7,0/8,0 e 10/11 m di profondità), con un valore di pendenza minore (1,6 ‰) rispetto al tratto precedente e simile a quelli osservati al largo della fascia prodeltizia. tratto b da lignano riviera a sabbiadoro la riva assume uno sviluppo convesso, con un’ampia spiaggia emersa (180 m) che passa ad una estesa piana di bassa marea (ca. 40-60 m) e intertidale sottomarina (340 m). e’ un tratto di spiaggia sostanzialmente in accrescimento con alle spalle (zona centrale), una duna litorale (4 a 5 m circa d’altezza), e nei tratti limitrofi opere di difesa aderenti in calcestruzzo. la spiaggia sottomarina manifesta una zona dinamica ampia 250 m, con due ordini di barre sottomarine e un’acclività di 9,0 ‰ circa. in questo tratto di litorale s’individuano cinque zone sottomarine a diversa acclività. nella presente situazione, però, i valori di pendenza sono nettamente inferiori a quelli visti precedentemente e danno al profilo della spiaggia un andamento più regolare, dove i cambiamenti di pendenza risultano meno accentuati (fig. 5; transetto l15-lignano). proseguendo verso la bocca di lignano (fig. 5; transetto l20-lignano) la spiaggia sottomarina fa risaltare un ulteriore addolcimento del fondale: in corrispondenza della convessità della linea di riva, la fascia a barre e truogoli raggiunge la massima estensione del paraggio (ca. 320 m), mediamente con due o tre ordini di barre ed eccezionalmente quattro. i profili tipici della spiaggia sottomarina di questa zona palesano tre intervalli, ad andamento regolare, con la presenza di fanerogame marine (cymodocea), che aumentano in ampiezza, e dunque diminuiscono gradualmente la loro acclività avvicinansi alla bocca (vedi fig. 5; transetto l20-lignano). segnatamente, le fanerogame si posizionano in una limitata area, a cavallo delle batimetriche 4,0/6,0, a largo della fascia costiera di lignano sabbiadoro, sulla rampa morfologica che porta al fondale più profondo. tratto a in prossimità del canale di accesso a lignano, la linea di riva è condizionata da una serie di interventi antropici (pennelli impermeabili ed opere di difesa aderenti) realizzati a salvaguardia dell’area urbanizzata retrostante e del suo ambito portuale. la spiaggia emersa risulta poco estesa (ca. 60 m) e fortemente antropizzata (anche con una serie di opere semifisse) per far fronte alla stagione turistica; verso mare è presente un terrazzo di bassa marea (come nel litorale precedente), ampio mediamente 40 m e fissato dall’aggetto dei pennelli. dopo questa distanza e con una forte pendenza inizia la zona a barre e truogoli. anche all’ interno della bocca lagunare il terrazzo di bassa marea (che si sviluppa tra le profondità di 0,5 e 1,0 m) trova la sua massima estensione, fino a delimitare il canale principale del delta inlet (fig. 5; transetto l27-lignano). nello specifico, il delta inlet di lignano (figg, 3 e 4) definisce un corpo sedimentario complesso che si protende di molto verso mare e che viene sostenuto da un canale principale. questo termina, dopo un andamento quasi rettilineo, con uno sbocco verso sudovest, allineandosi alla prevalente direzione delle bocche lagunari e delle foci dell’alto adriatico. il canale si approfondisce progressivamente verso mare, raggiungendo la profondità massima di 11,0 m e segue un andamento sinuoso con una prima deviazione verso oriente, con conseguente erosione della sponda, difesa da una scogliera in pietra a pezzatura grossolana. qui l’alveo assume una classica geometria asimmetrica con al centro un esteso campo di dune subacquee (di modeste dimensioni, h = 0,8 m e l = 20 m), disposte marginalmente rispetto alla direttrice principale di flusso. proseguendo verso il largo, il canale mostra un’ulteriore deviazione verso sud, sud-ovest con conseguente deflessione dei sedimenti sabbiosi verso le profondità maggiori e alla creazione di cordoni sottomarini 54 e. gordini, r. marocco & r. ramella marginali, con la barra longitudinale occidentale di minor sviluppo rispetto all’opposta. nel complesso, l’assetto della bocca lagunare, rimarca l’evidente progradazione verso mare e quindi la prevalenza della componente di riflusso rispetto a quella di flusso, con una componente longitudinale (da est ad ovest) resa palese dalla presenza di uncinature, forme lobate, propaggini sabbiose e forme lobate allungate. al lato orientale del canale (dalla battigia fino a 2,5 m), si sviluppa una vasta area a swash bars, con forme lunate alternate ad irregolari, continuamente rielaborate dal moto ondoso. anche il delta inlet della bocca di lignano e soprattutto gli accumuli laterali del canale principale, possono fornire materiale passibile di un utilizzo per il rifornimento artificiale delle spiagge dopo gli opportuni accertamenti sulla qualità dei depositi sanciti per legge. litorale occidentale (dalla foce del tagliamento a punta baseleghe) tratto e proseguendo più ad ovest la spiaggia emersa palesa la situazione evidenziata precedentemente (tratto d) con una sottile lingua sabbiosa (50 -100 m), delimita alle spalle dalla laguna-stagno costiero di revelino che comunica con il mare con una rotta di limitate dimensioni e profondità (20-40 m e -0,5 /-1,0 m, vedi fig. 5; transetti b08-bibione e b12-bibione). recentemente, anche in questa zona sono stati realizzati in situazione d’emergenza tre rubble-mound groins al fine di contrastare il processo d’arretramento in atto. l’erosione, verificatasi sopraflutto al pennello occidentale, fa ritenere che il loro dimensionamento (spaziatura e aggetto) non sia in grado di tamponare la situazione vigente. il carattere erosivo della spiaggia viene anche visualizzato dalla limitata estensione del terrazzo di bassa marea mostra (20-30 m) e un approfondimento costante del tratto intertidale della spiaggia fino al limite della zona a barre e truogoli (posta a 0,9 m di profondità e a 40/45 m dalla battigia). più al largo, il fondale è caratterizzato da una minima fascia dinamica (circa 100-150 m), sostenuta da una sola barra che talvolta risulta appena accennata o assente con un unico truogolo molto accentuato. ancora più al largo il fondale marino può essere suddiviso in tre profili tipici, corrispondenti a fasce di diversa acclività del conoide deltizio; • una prima fascia mossa da depressioni (da 130 m a cavallo dei 3,0 m di profondità, a circa 190 m dalla linea di riva) e zone in accumulo più estese (circa 400 m). il passaggio fra le due aree avviene con un gradino morfologico mediamente accentuato (5,9 ‰); • una seconda fascia, molto estesa (1600 m circa), prevalentemente sub-orizzontale; • un tratto finale, molto acclive che non trova riscontro nell’ala sinistra del delta. tratto f in questo settore del litorale si registra un graduale cambiamento del profilo di spiaggia sottomarina, con la comparsa di una zona sub-orizzontale interna, cui fa seguito la zona a barre e truogoli che si allarga progressivamente procedendo verso punta baseleghe (fig. 5; transetto b16-bibione). tale allargamento della zona dinamica è ben visibile in corrispondenza del piazzale zenith, dove raggiunge un’ampiezza di circa 250 m e comprende due ordini di barre e altrettanti truogoli, ad andamento irregolare. nello stesso profilo, dopo la zona dinamica, si riconosce una fascia ad andamento regolare con acclività media pari a 3,6 ‰. ancora più ad ovest la fascia a barre e truogoli si amplia ulteriormente, arrivando ad un’estensione massima di 250-340 m con 2-3 ordini di barre sottomarine. estremamente significativo risulta l’andamento delle isobate nel fondale prospiciente la zona piazzale zenith, tra i 3,0 e i 6,0 m di profondità che circoscrivono un’area in accumulo, derivante dall’erosione del tratto di spiaggia più orientale (fig. 4). in controtendenza rispetto alle aree sopra descritte, la parte centrale della costa di bibione mostra un’accentuata convessità verso mare. il confronto delle linee di riva della ctr del veneto (1999) e quella dei nostri rilievi (fig. 3) evidenzia una tendenza alla progressione naturale di questo tratto di litorale con valori di avanzamento della spiaggia emersa, pari a circa 10 m. l’arenile qui raggiunge il massimo valore (200-250 m) e mostra una pendenza regolare, senza rotture determinate da morfologie naturali (berma ordinaria e di tempesta) e viene delimitato da opere di difesa longitudinali aderenti che insistono in un’area depressa che si sviluppa fino al suo limite settentrionale. il terrazzo di bassa marea è molto esteso (60 m circa) e degrada dolcemente verso la fascia dinamica del litorale che è anch’essa abbastanza ampia (complessivamente 70-80 m). segue un fondale molto omogeneo (fig. 5; transetto b16-bibione) con una graduale diminuzione della pendenza passando dalla zona a barre e truogoli (7,6 ‰), a quella immediatamente seguente (5,4 ‰); tendenza questa, che viene confermata anche verso mare, dove dopo un modesto gradino morfologico (6,8 ‰), la spiaggia sottomarina mostra un assetto quasi sub-orizzontale con acclività pari a 2,8 ‰ (3,0 ‰ a circa 3 km dalla costa). tratto g proseguendo verso la bocca di baseleghe la spiaggia si assottiglia (ampiezza circa 50-70 m), senza però evidenziare processi erosivi in atto (fig. 5; transetto b24-bibione). il confronto dei rilievi 1999 con quelli 2003, confermano tuttavia la tendenza alla stabilità del litorale. la sua parte intertidale ha un’estensione di circa 70 m, con un evidente terrazzo di bassa marea delimitato da una barra (posta ad una profondità di – 0,7 m). tratto h in coincidenza con la freccia litorale che delimita la laguna di baseleghe (fig. 5; transetto b29-bibione) si assiste nuovamente ad un ampliamento della spiaggia emersa (circa 150 m) e alla presenza di apparati dunari di modesta elevazione (1-2 m) che si sviluppano parallelamente alla linea di riva dove sono presenti le classiche morfologie di accrescimento di una freccia litorale. la battigia si raccorda dolcemente al terrazzo di bassa marea (ampio 25 m circa) che a sua volta si congiunge dolcemente alla zona dinamica. in questa area tra le isobate 0,5 e 1,5 si riconoscono le tipiche morfologie legate al moto ondoso (piattaforma di spit, sensu, ashley et al., 1990, barre di swash e forme lobate) disposte parallelamente, con spiccata espansione verso ovest, tanto da occludere o trascinare sempre 55dinamica morfologica del litorale ... nella medesima direzione la bocca di baseleghe. questo processo al prolungamento verso occidente dell’ala destra del delta tilaventino e all’occlusione della bocca di baseleghe è ormai noto da molto tempo (zunica, 1971; catani et al., 1978; catani et al., 1982) e viene contrastato oggi, come in passato, attraverso la periodica escavazione del canale d’accesso al porto. si fa presente che anche queste escavazioni possono fornire ingenti quantità di materiale per il ripascimento delle aree in erosione. la spiaggia sommersa prossima a punta baseleghe mostra un carattere relativamente stabile. la sua parte verso terra è contraddistinta da un’estesa zona dinamica (250-270 m), alimentata da due ordini di barre litorali seguite dai rispettivi truogoli. si passa, poi, quasi senza soluzione di continuità, ad un fondale prevalentemente pianeggiante, caratterizzato essenzialmente da due fasce a modesta pendenza. la prima di queste fasce si estende dalla progressiva 280 m a 1100 m dalla battigia, tra le profondità da 2 a 7 m e con una pendenza di 5,5 ‰. la seconda, con acclività pari a 2,6 ‰, si sviluppa da 1280 a 3000 m dalla battigia, tra le profondità rispettivamente di 7 e 12 m (fig. 5; transetto b29-bibione). il protendimento verso mare del delta inlet è sottolineato in modo particolare dall’andamento delle isobate da 1,5 a 2,5 m che si collocano in posizione avanzata rispetto alle aree adiacenti. il passaggio alle profondità maggiori avviene con una superficie ad acclività pari a 6,3 ‰, che dalla progressiva 1300 m passa gradualmente verso mare ad un valore di 3,6 ‰. anche queste parti più esterne del profilo di spiaggia non presentano morfologie particolari, mantenendo la solita superficie debolmente inclinata che si raccorda ai fondali del golfo di venezia. rispetto al delta inlet opposto (bocca di lignano) quello di baseleghe è meno sviluppato (sia verso terra che verso mare) a dimostrazione che i flussi di marea qui sono meno forti e, soprattutto che nel versante a mare, l’azione della dispersione marina è di molto superiore a quella determinata dai flussi di marea. 5. analisi morfologica quantitativa della spiaggia a completamento di questo studio è stata condotta una breve indagine morfologica quantitativa (sensu, carobene, brambati, 1975; carobene, 1978) al fine di definire l’estensione, le quote e le pendenze e gli elementi morfologici peculiari delle diverse porzioni della spiaggia emersa, intertidale e sottomarina. la finalità dell’analisi è stata quella di identificare su base morfologica le condizioni di stabilità o instabilità del litorale e ciò anche per individuale il dimensionamento ideale del profilo di spiaggia nei diversi settori del paraggio. segnatamente è stata indagata in maniera particolare la zona che si estende dalla battigia alla “zona a barre e truogoli”, che già in altre ricerche si è dimostrata il termometro della situazione erosiva o di accrescimento del litorale (vedi catani et al., 1982). a tal fine, si è appurato che i risultati migliori si ottengono dall’analisi delle relazioni che legano la distanza tra linea di battigia e il piede della barra sottomarina esterna (lb-p) e la sua pendenza α (fig. 6). si è accertato anche, com’era del tutto prevedibile, che sussistono relazioni di dipendenza tra ampiezza della zona sottomarina (spiaggia intertidale + zona a barre e truogoli), la sua pendenza e le condizioni d’erosione o stabilità del litorale definite attraverso osservazioni dirette e validate dal confronto con dati pregressi. infatti, i punti che rappresentano questi parametri morfologici, calcolati per ogni sezione topo batimetrica (sono stati utilizzati esclusivamente, anche per omogeneità, i soli dati desunti dall’ultimo rilievo, maggio-giugno 2003) mostrano una regressione lineare d’equazione y = 0,0022 x + 1,1489 e r2 = 0,7386. in altri termini la pendenza della spiaggia, in condizioni d’omogeneità tessiturale dei sedimenti, è in relazione con la sua stabilità e permette di eseguire una zonizzazione delle aree in erosione da un lato e di quelle in progressione o in stabilità al lato opposto. alla maggiore acclività e minore estensione della zona a 56 e. gordini, r. marocco & r. ramella fig. 6 diagramma “distanza tra linea di battigia e piede della barra sottomarina esterna (lb-p) e la pendenza della retta lb-p (α). diagram “distance between the foreshore and the foot of the submerged external bar (lb-p) and the dip of the line lb-p (alfa.) barre e truogoli, corrisponde una concentrazione di punti (raggruppamento r1); viceversa in condizioni opposte (r2). tra questi due raggruppamenti o famiglie di tratti di litorale si colloca poi, una fascia intermedia di transizione graduale tra le due. all’interno del raggruppamento r1 si ubicano: • i tratti di spiaggia ad ovest delle opere marittime di difesa costruite in prossimità del faro di punta tagliamento (transetti b5; b6; b7; b8 e b9). come precedentemente osservato quest’area manifesta evidenti processi d’ erosione trascorsi ed in atto, che hanno portato ad un notevole assottigliamento della spiaggia emersa, con la presenza di rotte e varchi; • i tratti di spiaggia ad est della foce del tagliamento (lignano riviera), difesi da opere trasversali, eseguite negli anni 1966-1979, e soggetti tutt’oggi ad evidenti processi erosivi ( l4; l5; l6; l7; l8; l9 e l10) . • le strette spiagge del margine occidentale della bocca di lignano, anch’esse caratterizzate dalla presenza di opere di difesa impermeabili ( l27; l28 e l29). nell’ambito del raggruppamento r2: • si ubicano i rimanenti tratti del litorale ad eccezione di quelli di raccordo dell’area del faro e di bibione (transetti b 10, b 11 e b 12), e tra lignano riviera e sabbiadoro (l11). questa famiglia di punti raggruppa le aree di litorale dove sia in base ad osservazioni dirette (particolari morfologie osservate sulla spiaggia emersa ed intertidale), sia in base a confronti cartografici recenti (sovrapposizione della linea di costa definita dalle carte tecniche regionali delle regioni veneto e friuli venezia giulia, 1999 -1990 e quella dei presenti rilievi di maggio-giugno 2003) presentavano caratteri di stabilità o tendenza alla progressione naturale. se da un lato la distinzione tra le due famiglie che raggruppano tratti di litorale deltizio ai limiti del diagramma sono evidenti, dall’altro bisogna specificare che non tutti i punti che cadono nell’area di stabilità o progressione si trovano sotto una condizione acclarata. quest’ultimo fatto sembra essere spiegato come la tendenza di queste aree in lieve erosione a portarsi verso una relativa stabilità, oppure, all’inverso dalla condizione di stabilità relativa verso una condizione di erosione tendenziale (es. punti relativi ai transetti l12 e l3 o nel caso del litorale di bibione, b13 e b14). anche se permangono queste incertezze sull’interpretazione di un numero ristretto di dati, si può ritenere che nell’insieme il diagramma fornisce un ottimo strumento per discriminare aree tendenzialmente in erosione, da quelle stabili o in progressione naturale. altri parametri morfologici quantitativi delle spiagge forniscono informazioni analoghe, ma questo permette di definire con una certa precisione la pendenza e la distanza che le spiagge devono raggiungere in condizioni d’equilibrio con gli agenti meteomarini. 6. variazioni batimetriche e volumetriche del fondale marino dal ciclo erosivo invernale a quello deposizionale estivo nell’arco annuale scandito dal periodo invernale (settembre ed ottobre 2002) a quell’estivo (maggio e giugno 2003), sui 18 km circa di litorale si sono definiti i principali spostamenti del materasso sabbioso. i bilanci volumetrici eseguiti per ogni transetto sono riportati nelle tabelle i e ii. preme sottolineare che l’errore stimato sul valore di profondità rilevato (+/-7 cm), può portare a sovrastimare o sottostimare i volumi calcolati e ciò soprattutto, quando le variazioni di profondità sono minime e si ripercuotono su estese superfici. per questo motivo non si sono prese in considerazione le variazioni con valore eguale o inferiore a questo, anche se calcolate. ne consegue che le variazioni dei fondali che assommano a valori prossimi a +/15-20 m3/m, devono essere considerate solamente indicative di una tendenza del litorale, non variazioni effettive. la ripetizione dei rilievi nei due periodi ha confermato che i principali cambiamenti della spiaggia sottomarina avvengono quasi esclusivamente nella zona dinamica a barre e truogoli, con la traslazione delle barre più al largo dalla posizione estiva, durante la stagione invernale. ma oltre a questa fascia, tipicamente soggetta a variazioni, ne sono emerse altre aree e segnatamente (fig. 7): • una prima ubicata sul fronte deltizio, in cui sono presenti numerose barre e cordoni litorali che si muovono verso ovest, sospinti dalla corrente litoranea e dai mari del i quadrante, mentre subiscono una dispersione diversa, per mari del ii e iii quadrante. in questa zona e soprattutto in prossimità della foce si riscontrano locali approfondimenti dei fondali seguiti da accumuli che tendenzialmente divengono prevalenti. questi fenomeni diventano evidenti in corrispondenza del pennello occidentale di foce (vedi transetti l03 e l04; tab. i), che continua a trattenere nell’area, i contributi solidi del tagliamento, non permettendo l’alimentazione del litorale lignanese; • una seconda area, ad ovest di bibione, localizza ad una distanza compresa tra 800 e 1000 m dalla costa e a profondità variabile da 5,0 a 7,0 m, dove si riscontra una modesta rottura di pendenza (acclività massima pari a 10,5 ‰) che è possibile seguire per circa 2,5 km parallelamente alla costa (ben evidente nei transetti b19; b20; b21; b22 e b23). qui si registra una variazione massima di spessore di circa 0,5 m, ed un deficit sedimentario valutato lungo il transetto in 67,6 m2; • una terza, più ad est, presente sul fondale marino antistante bibione, che si estende da 870 a 980 m dalla costa, a cavallo della batimetrica 6. qui il fondale è relativamente elevato e si presenta fortemente accidentato per avvallamenti e gobbosità a geometria variabile, ben visibili lungo il transetto b11 (ma anche nei transetti dal b07 al b15). tali asperità, distribuite sul margine occidentale dell’alto morfologico (fig. 4), non presentano similitudini (in ampiezza e lunghezza d’onda) con le morfologie tipiche dalla zona a barre e truogoli. ritornando alla zona a barre e truogoli, nell’area veneta essa è maggiormente sviluppata verso ovest (da bocca di baseleghe alla porzione centrale del litorale), mentre perde di estensione e viene quasi completamente sostituita da aree in erosione in prossimità della foce tilaventina. dette aree, disposte parallelamente e/o leggermente inclinate rispetto alla linea di riva, sono particolarmente evidenti in prossimità di pineta punta faro e lame di revelino dove si riscontrano deficit 57dinamica morfologica del litorale ... 58 e. gordini, r. marocco & r. ramella fig. 7 variazione dello spessore dei sedimenti dei fondali risultante dai rilievi ogs 2002-2003. variation of the sediment thickness as resulted from the 2003 ogs surveys. sedimentari compresi tra 0,2 e 0,45 m3/m2. l’asportazione di materiale verso riva, viene tuttavia in buona parte compensata dalla deposizione al largo (0,13 m3/m2). nell’area friulana la zona a barre e truogoli è molto sviluppata in corrispondenza di lignano sabbiadoro e decresce fino alla quasi scomparsa verso lignano riviere e pineta. come è stato già evidenziato precedentemente, la spiaggia di sabbiadoro presenta, a lungo periodo, un carattere stabile tendente a periodi di progressione. tale situazione è confermata anche a breve periodo dal confronto dei rilievi eseguiti e dalla conformazione stessa del fondale marino (terrazzo intertidale, zona a barre e truogoli, fondale sub pianeggiante che si estende fino a 2 km dalla costa, ecc). l’area di bocca lagunare (bocca di lignano), presenta accumuli sotto forma di depositi allungati parallelamente alla direzione di sviluppo del canale principale. sulla base dei rilievi eseguiti non compaiono alcune evidenze macroscopiche di deficit o accumuli sedimentari in prossimità della bocca. queste probabilmente potranno emergere solamente da un’analisi effettuata in più lungo periodo. comportamento diverso, denuncia il tratto di litorale che va da lignano riviera a pineta; qui si osserva la quasi stabilità della zona, eccezion fatta, per le limitate aree d’approfondimento dei fondali (dell’ordine di 0,1÷ 0,2 m e quindi non significative, dati i limiti di accuratezza dei rilievi), poste al piede dei pennelli presenti nell’area. nelle tabelle i e ii oltre ai bilanci volumetrici calcolati dal confronto dei rilievi ogs 2002 e 2003, viene riportata anche la tendenza evolutiva del litorale che emerge dal confronto dell’ultimo rilievo ogs 2003 con quelli del 1997 (litorale di bibione) e della regione friuli venezia giulia (brambati, 1987 spiagge di lignano). in grassetto sono stati messi in evidenza i valori volumetrici che possono essere considerati meno influenzati dagli errori di misura e dunque considerati attendibili per un primo bilancio volumetrico del trasporto litorale. nell’ultima colonna si sono riportati i confronti con le situazioni precedenti. in particolare, dai transetti eseguiti in prossimità della foce, emerge che l’apparato deltizio presenta un consistente incremento volumetrico. questo dato è molto importante poiché questi accumuli possono essere utilizzati (dopo i controlli previsti per legge) per il ripascimento delle spiagge e, nel contempo, per liberare il passo marittimo d’accesso ai porti interni alla foce. si è cercato pertanto di quantificare con la massima precisione possibile e nell’intervallo temporale esaminato, l’ammontare e la relativa stabilità di tale accumulo di sedimento. per eseguire questa stima è stato utilizzato il programma surfer version 8.00 surface mapping system della golden software, inc., colorado. attraverso questo software è stato possibile 59dinamica morfologica del litorale ... tabella i variazioni volumetriche e tendenze evolutive dei fondali del delta del f. tagliamento (ala orientale). volume variations and evolutive trends of tagliamento river delta (eastern sector). transetto deficit deposizione variazione volumetrica tendenza evolutiva risultante dal confronto (m3 / m) dei profili ogs 2003 con quelli da rilievi ogs 2002-2003 brambati (1987) transetto l01 x + 64,3 consistente ripascimento al largo erosione sottocosta transetto l02 x + 24,1 leggera tendenza al ripascimento al largo erosione sottocosta transetto l03 x + 274,7 ripascimento al largo leggera tendenza all’erosione sottocosta transetto l04 x + 197,3 ripascimento al largo leggera tendenza all’erosione sottocosta transetto l05 x + 63,9 stabile leggero ripascimento sottocosta transetto l06 x 9,1 stabile leggero ripascimento sottocosta transetto l07 x + 9,3 stabile leggero ripascimento sottocosta transetto l08 x + 3,3 ripascimento sottocosta stabile con leggera tendenza all’erosione al largo transetto l09 x 39,9 leggero ripascimento sottocosta stabile con tendenza all’erosione al largo transetto l10 x 18,8 stabile transetto l11 x 6,4 stabile al largo leggero ripascimento sottocosta transetto l12 x + 57,6 stabile al largo leggera tendenza all’erosione sottocosta transetto l13 x 7,9 stabile leggera tendenza all’erosione sottocosta transetto l14 x + 17,3 stabile transetto l15 x + 6,6 stabilità transetto l16 x + 27,8 --transetto l17 x + 7,4 --transetto l18 x + 3,1 --transetto l19 x 5,4 --transetto l20 x 1,1 --transetto l21 x + 5,4 ripascimento sottocosta stabilità al largo transetto l22 x + 7,5 --transetto l23 x + 14,1 --transetto l24 x 18,0 --transetto l25 x + 4,9 stabilità sottocosta leggera tendenza al ripascimento al largo transetto l26 x + 11,3 transetto l27 x + 7,9 --transetto l28 x + 229,15 --transetto l29 x 2,9 --transetto l30 x + 5,3 --60 e. gordini, r. marocco & r. ramella e. gordini, r. marocco & r. ramella tabella ii variazioni volumetriche e tendenze evolutive dei fondali del delta del f. tagliamento (ala occidentale). volume variations and evolutive trends of tagliamento river delta (western sector). transetto deficit deposizione variazione volumetrica tendenza evolutiva risultante dal confronto (m3 / m) dei profili ogs 2003 con quelli da rilievi ogs 2002-2003 italrilievi s.n.c (1997) transetto b01 x 74,3 --transetto b02 x + 156,3 -- transetto b03 x + 79,9 --transetto b04 x + 74,3 stabilità al largo ripascimento sottocosta transetto b05 x + 82,8 tendenza al ripascimento transetto b06 x + 100,0 leggera tendenza all’erosione al largo leggera tendenza all’erosione sottoriva transetto b07 x + 44,3 erosione al largo erosione sottocosta transetto b08 x + 11,2 erosione al largo erosione sottocosta transetto b09 x 3,3 erosione al largo erosione sottocosta transetto b10 x + 46,2 erosione al largo erosione sottocosta transetto b11 x 50,0 erosione al largo erosione sottocosta transetto b12 x + 34,6 erosione al largo erosione sottocosta transetto b13 x 48,6 --transetto b14 x 64,7 --transetto b15 x + 0,2 erosione al largo erosione sottocosta transetto b16 x + 13,3 ripascimento sottoriva leggera erosione al largo transetto b17 x 4,3 ripascimento sottoriva stabilità con tendenza al rinascimento al largo transetto b18 x 7,4 ripascimento sottoriva stabilità al largo transetto b19 x + 0,6 ripascimento sottoriva stabilità al largo transetto b20 x 14,9 ripascimento sottoriva stabilità al largo transetto b21 x + 45,4 leggero ripascimento sottoriva stabilità al largo transetto b22 x + 11,0 leggero ripascimento sottoriva stabilità centrale ed erosione al largo transetto b23 x 71,8 ripascimento sottoriva stabilità con tendenza al rinascimento al largo transetto b24 x 18,8 ripascimento sottoriva stabilità con tendenza all’erosione al largo transetto b25 x + 12,3 ripascimento sottoriva stabilità con tendenza all’erosione al largo transetto b26 x + 0,6 ripascimento sottoriva stabilità al largo transetto b27 x + 11,8 ripascimento sottoriva stabilità al largo transetto b28 x + 4,6 ripascimento sottoriva erosione al largo transetto b29 x + 28,4 --transetto b30 x + 22,5 leggero ripascimento sottoriva stabilità centrale ed erosione al largo transetto b31 x + 8,5 ripascimento sottoriva stabilità al largo estrarre i due dem (digital elevation model), inerenti l’area deltizia per i due rilievi batimetrici ogs 2002 e 2003. successivamente, sempre con lo stesso software, sono stati creati con il metodo triangular with linear interpolation, altrettanti grid a maglie quadrate che rappresentano la superficie reale basata sulle informazioni reali disponibili (rilievo eseguito). la differenza fra le due superfici così ottenute ha permesso di raffigurare le variazioni di spessore subita dal litorale (fig. 8). dal confronto emerge che in prossimità della foce, le aree soggette a variazioni dei fondali superiori all’errore stimato sono pari a 5.809.408 m2 con zone in accumulo pari a 4.770.317 m2 e altre in approfondimento pari a 1.039.091 m2. il volume conseguente è risultato essere pari a ca. 570.000 m3 (volume positivo), contro uno di ca. 75.000 m3 (perdite), con un bilancio positivo di ca. 495.000 m3. tenendo presente che l’apporto solido complessivo (dalle ghiaie alle peliti) stimato per il tagliamento (brambati; 1987) è di circa 1.300.000 m3/anno e che gran parte del materiale è costituito da depositi fini (ca. 70 %) ne deriverebbe che complessivamente in un anno transitano via foce 390.000 m3 di sedimenti grossolani. secondo i calcoli precedenti (accrescimento riscontrato di circa 494.274 m3), diventa palese che all’input fluviale si deve aggiungere anche quello del trasporto lungo riva catturato dal pennello liquido del fiume. sta di fatto che sabbie si accumulano nell’area di foce in lassi temporali a scala annuale. rimane da appurare adesso se questi accumuli permangono nel tempo. per valutare questo si sono presi in considerazione i dati pregressi, editi da brambati (1987) sulla base del confronto dei rilievi del 1969 con quelli 1985. l’autore, stimando un valore medio su di un lungo periodo e in anni non molto vicini ad oggi, registra una situazione opposta a quella da noi riscontrata, con un deficit di 177.875 m3 di depositi distribuito su una superficie di 1.060.000 m2 (ca. 17 cm su metro quadrato). visti i risultanti emersi operando a scala pluriennale, si sono messi a confronto i rilievi ogs 2003 con quelli ricavati dal cnr nel 1969 (riportati da brambati, 1987) e con quelli del 1985 dello stesso autore. si specifica che per uniformità, è stata preventivamente eseguita, con il procedimento di confronto fra grid prima esposto (utilizzando il software surfer 8), la comparazione fra i rilievi cnr 1969 con quelli del 1985. il raffronto eseguito con questo metodo ha mostrato un deficit sedimentario leggermente superiore rispetto a quello prospettato dall’autore (fig. 9 a). anche se i valori assumono moduli leggermente diversi (-177.875 m3 contro i -195.728 m3) restano comunque confermate 61dinamica morfologica del litorale ... fig. 8 variazioni dello spessore dei sedimenti nell’area deltizia (rilievi ogs 2002-2003) e calcolo dei volumi. variation of the sediment thickness in the delta area (2002-2003 ogs surveys) and volume computation. le aree interessate dai maggiori cambiamenti (erosioni), che si manifestano sul fronte deltizio. i bassi fondali prossimi al litorale, mostrano invece un’abbondante deposizione di sabbie, valutabili in 1,0 ÷ 1,5 m di spessore nell’ala occidentale, e valori leggermente inferiori (0,4 ÷1,0 m) nel lobo orientale. va comunque sottolineato che anche se il bilancio volumetrico netto dell’intero paraggio risulta negativo (195.729 m3), le spiagge che bordano il delta manifestano processi di accumulo (non vale lo stesso, come abbiamo già osservato precedentemente, per quelle prossime al faro di punta tagliamento). completamente diversa risulta invece essere la situazione nei 18 anni seguenti (dal 1985 al 2003 fig. 9 b); le aree in accumulo perdono sedimenti a favore di quelle del fronte deltizio. nello specifico i maggiori accumuli si manifestano fra le batimetriche 3 e 5 sul delta front (spessore medio 1,5 m) con erosioni molto evidenti a ridosso del pennello di foce con al lato opposto, un forte arretramento della linea di costa e la creazione di un canale di sovraescavazione (spessore dei sedimenti asportati mediamente pari a 1,5 m) che si posiziona al piede delle nuove barriere frangiflutti realizzate. il bilancio di materiale indica che le aree soggette a variazioni sono pari a ca. 1.272.000 m2, delle quali, in accumulo 899.000 m 2 e in approfondimento 373.000 m2. il volume conseguente è risultato essere di ca. 619.000 m3 (volume positivo), contro 177.000 m3 (perdite), con un bilancio netto positivo di ca. 442.000 m3. per completare l’analisi è stato realizzato il confronto dei fondali su un intervallo temporale di 34 anni (rilievi cnr 1969 ogs 2003; fig. 9 c). lo scenario emerso mostra un carattere stabile del sistema tendenzialmente volto alla progressione. il bilancio volumetrico netto è di ca. 242.000 m3 (corrispondente ad un volume medio annuo pari a 7100 m 3/anno), con un volume positivo di 397.000 m3 (distribuito su di una superficie di 847.000 m2) mentre quello negativo risulta di ca.155.000 m3 (439.000 m2). in linea generale, la distribuzione di queste aree risulta abbastanza conforme a quella evidenziate nello studio a breve termine (ogs 2002-2003) e nell’evoluzione deltizia avvenuta dopo il 1985. in sintesi, le variazioni da noi riscontrate trovano un riscontro con le situazioni del passato: emerge dunque un incremento del materasso sedimentario sul fronte deltizio, con un predominante input proveniente da est che by -passa il pennello di foce e importanti arretramenti in 62 fig. 9 variazioni dello spessore dei sedimenti nell’area deltizia e calcolo dei volumi; a situazione 1969-1985; b situazione 1985-2003; c situazione 1969-2003. variation of the sediment thickness in the delta area and volume computation; a1969-1985 situation; b-1985-2003 situation; c-1969-2003 situation. e. gordini, r. marocco & r. ramella corrispondenza dello sbocco a mare del fiume e delle aree costiere immediatamente connesse ad esso. questo trend avviene attraverso periodi di scarso apporto solido (1969-1985; brambati 1987), seguito da fasi di stabilità più o meno lunghe, alternate a brevi periodi di forte apporto (2002-2003). in questo meccanismo risulta di fondamentale importanza l’azione disperdente operata dal moto ondoso e dalle correnti litoranee che ridistribuiscono in diverse settori, i nuovi sedimenti che entrano nel bilancio del litorale. dal confronto dei rilievi ogs 2002-2003, è possibile definire che: • i cambiamenti maggiori della spiaggia sottomarina si riscontrano in corrispondenza della zona dinamica a barre e truogoli e sono determinati dalla traslazione delle barre sabbiose da terra verso mare; • nel settore più profondo della spiaggia sottomarina le variazioni sono minime ad eccezione di due aree, localizzate a largo della costa veneta (ad una distanza compresa tra 800 e 1000 m dalla linea di riva e profondità variabile tra 5,0 e 7,0 m) e poste a cavallo di un gradino morfologico; • in corrispondenza delle bocche lagunari e della foce si registrano traslazioni di sedimento trasversalmente al litorale; • nell’area di foce del tagliamento si sono individuate due zone in accumulo, una antistante il pennello orientale (estensione: 52.000 m2; spessore minimo: 0,2÷0,3 m; spessore massimo: 1,4 m, volume stimato: 46.000 m3) e l’altra immediatamente a fronte della foce (estensione: 62.000 m2; spessore minimo: 0,2 m; spessore massimo: 1,4 m, volume stimato: 48.000 m3); • complessivamente, pur registrando locali perdite di fondale in corrispondenza dell’area prettamente di foce, l’area deltizia presenta un bilancio volumetrico positivo pari a ca. 494.000 m3; • il confronto con le variazioni subite dal litorale risultanti dai rilievi precedenti (bibione italrilievi s.n.c., 1997; lignano brambati, 1987) ha permesso di valutare le tendenze evolutive delle spiagge. 7. considerazioni conclusive i risultati ottenuti dall’analisi dei profili batimetrici della spiaggia intertidale e sottomarina, uniti alle osservazioni dirette condotte sulla spiaggia emersa e quelli più generali dedotti dalla prospezione lidar, permettono di tratteggiare una prima situazione morfodinamica delle spiagge del delta tilaventino e di tracciare una sua zonizzazione in tratti di litorale soggetti a processi erosivi, aree tendenzialmente stabili o in fase di leggera progressione. per alcuni di questi tratti, poi, è stato possibile valutare quantitativamente le variazioni registrate in un ciclo annuale (2002-2003) e, utilizzando dati pregressi, in due segmenti pluriennali (1969 – 2003 e 1985 – 2003). per quanto attiene alla spiaggia sottomarina emerge che, salvo rare eccezioni, questa rimane generalmente stabile nel periodo considerato salvo in corrispondenza delle bocche lagunari e alla foce del tagliamento e di due zone dell’ala occidentale del delta. segnatamente, incrementi e decrementi dei depositi di fondo diventano sensibili in corrispondenza della foce del tagliamento e delle bocche lagunari di lignano e porto baseleghe. qui i pennelli liquidi delle acque fluviali e lagunari deviano verso il largo i depositi che transitano in queste zone, incrementando così i fondali immediatamente prospicienti. diversa è invece la situazione riscontrata al largo di bibione (tra 3,0 e 6,0 m di profondità) dove in un’area piuttosto estesa si rinviene un accumulo di sedimenti che provengono dall’intensa erosione costiera delle spiagge immediatamente più ad est (litorale di bibione – lame di revelino e punta faro). la relativa stabilità di quest’accumulo negli anni di rilievo fa supporre che i depositi una volta abbandonati in quest’area dagli agenti che hanno determinato l’erosione costiera, tendano a stabilizzarsi e permanere nel tempo, non venendo più ripresi dall’azione di dispersione del moto ondoso. ciò determina una condizione che, almeno in prima ipotesi e data la loro granulometria si prospetta ottimale per un utilizzo come cava di prestito di questi accumuli da destinare ad opportune ricariche artificiali della spiaggia di pineta punta faro – lame di revelino, soggetta ad intensa erosione. altri fattori che inducono a questa ipotesi di intervento è la presunta affinità granulometrica dei sedimenti che in sostanza sono quelli erosi dal litorale che si vuol ricomporre e anche la limitata distanza fra area di presa e spiaggia da risanare. e’ evidente, comunque, che quest’operazione di riequilibrio del litorale, se attuata, deve essere corredata da opportune opere di ritenuta di questo materiale che viene riportato artificialmente alle condizioni iniziali. per quanto attiene, invece, le aree all’interno della zona a barre e truogoli e quelle intertidali, emerge che i tratti soggetti a maggiori cambiamenti sono: • quelli contraddistinti dalla migrazione delle barre nell’ambito dell’area più dinamica della spiaggia sottomarina; • quelli in continua erosione (o progressione) determinata da fattori naturali e/o dalle opere di difesa che si sono stratificate lungo il litorale; • la foce del tagliamento e le bocche lagunari. i cambiamenti volumetrici nell’area delle barre e truogoli sono determinati quasi sempre da semplici traslazioni verso mare o verso terra delle barre e non da reali impoverimenti complessivi della zona dinamica; in altre parole le perdite corrispondono quantitativamente agli acquisti con un bilancio complessivamente in pareggio. in generale, come dimostrato da più lavori, durante il periodo estivo le barre si trovano in posizione più ravvicinata alla linea di costa e viceversa durante quello invernale. differente è invece la situazione nell’area della spiaggia intertidale dove erosioni e progressioni della linea di riva e dei fondali del terrazzo di bassa marea sono causate da fattori naturali a volte agevolati, indotti e altre volte, vanamente ostacolati dalle opere di difesa marina. così nell’ala orientale del delta, nei litorali connessi alla bocca lagunare di lignano, si delinea una leggera instabilità delle spiagge anche se difese da una serie di pennelli impermeabili ed opere aderenti. qui le maggiori variazioni degli arenili sono condizionate dalle continue modificazioni interne della bocca lagunare (argini marginali e canali interni) che si ripercuotono sui lidi adiacenti e dall’altro, dalla deviazione verso il largo del trasporto litorale attuato dal suo pennello liquido. la porzione centrale del litorale di lignano mostra un 63dinamica morfologica del litorale ... carattere tipicamente stabile con fasi di progressione naturale, confermata anche a lungo termine. il tipico profilo di spiaggia mostra un’estesa parte emersa, come anche quella intertidale che si raccorda dolcemente ad una sviluppata zona a barre e truogoli. a questa, verso mare, succede un fondale sub -pianeggiante che si unisce al protendimento sabbioso dell’ebb tidal delta di lignano. più ad ovest, le spiagge di pineta lungomare adriatico, manifestano anch’esse una situazione tendenzialmente stabile, con temporanee condizioni regressive determinate dalla carenza di apporti sedimentari provenienti da est, secondo il trasporto prevalente, ma anche da ovest, a causa dell’effetto schermante di diverse opere di difesa che impediscono l’arrivo di nuovi sedimenti dal tagliamento. la situazione più critica, comunque, si registra in corrispondenza delle spiagge di riviera, difese vanamente da una serie di pennelli che hanno solo in parte mitigato l’erosione in atto da tempo. in questo tratto di litorale è evidente l’assenza di nuovi arrivi di sedimenti da ovest, come da est e il prevalente trasporto perpendicolare alla spiaggia, in parte determinato anche da una convergenza del moto ondoso. per tutti questi motivi questo tratto di litorale necessita, quasi obbligatoriamente, di un’alimentazione forzata, con ripascimenti di opportuni depositi prelevati in aree prossimali e il loro contenimento con idonee opere marittime. stante questa situazione, nel dettaglio si segnala che i lunghi pennelli di sbarramento e la loro serie ravvicinata, più che una cattura dei depositi che transitano lungo riva hanno solamente prodotto una parziale stabilizzazione delle sabbie all’interno delle celle tra due pennelli contigui. nel versante opposto, nell’ala occidentale del delta, dopo la zona prettamente di foce, si registra una situazione abbastanza simile a quella prima riscontrata: il litorale più orientale di bibione evidenzia una sensibile instabilità che ha portato recentemente, alla realizzazione di tre pennelli permeabili al fine di fermare la situazione erosiva in atto. l’aggetto e la spaziatura di queste opere, comunque, non appaiono le più indicate date le reali caratteristiche di trasporto di questo tratto di litorale. condizioni evolutive distinte esibiscono la parte centrale e occidentale del litorale di bibione, contrassegnate essenzialmente da una situazione stabile volta alla progressione. nello specifico, i caratteri peculiari del tratto centrale dell’ala deltizia (la configurazione convessa della linea di riva, l’estensione e la pendenza della spiaggia emersa, l’ampiezza della zona intertidale), confermano la stabilità della stessa e suggeriscono un carattere tendenzialmente deposizionale. proseguendo ancora verso l’estremità del delta (bocca di baseleghe), la spiaggia, dopo una prima riduzione dell’ampiezza (non determinata da una regressione in quanto stabile nel tempo considerato), palesa un notevole sviluppo nella parte intertidale ed uno spiccato allungamento verso ovest. ciò determina una progressiva occlusione e un trascinamento in questa direzione, della freccia litorale dell’ala occidentale del delta. anche la spiaggia più al largo confermano questa tendenza, mostrando le tipiche bedforms, legate al moto ondoso, che si generano nelle zone sub pianeggianti prossime alle bocche lagunari. la situazione più complessa dell’intero litorale si registra alla foce del tagliamento e alle sue sponde dove una serie di opere di difesa parallele e trasversali realizzate alla destra a partire dal 1966, probabilmente con finalità differenti, sono state costruite al fine di contrastare la naturale evoluzione regressiva del tratto apicale del delta. senza entrare nel merito all’attuale funzionalità di queste opere, si vuol qui sottolineare che se hanno bloccato, in parte, o generalmente rallentato i processi erosivi in atto da tempo, hanno però determinato condizioni di instabilità nelle aree immediatamente adiacenti. a ciò si aggiunga l’impatto visivo di queste costruzioni antropiche (barriere frangiflutti in massi) che contrasta con l’equilibrio delle forme naturali, tipico di una spiaggia e a maggior ragione in un delta di un fiume che viene considerato uno dei più naturali d’europa. nel versante opposto, il litorale viene pesantemente condizionato da pennello di foce (eseguito nel 1963) e recentemente accorciato. complessivamente nell’area fociale si assiste ad un progressivo arretramento della spiaggia emersa (parte occidentale) con messa a nudo dei depositi di lama sottostanti, alla quasi scomparsa del terrazzo di bassa marea, all’assottigliamento della zona a barre e truogoli, sostenuta da un’unica barra. le scogliere variamente sagomate, i tubi tipo longard, riempiti di sabbia, le continue alimentazioni artificiali della spiaggia con materiale scavato dalla foce (ca. 24.000 m3 di sedimenti nel solo anno 2005, con previsioni future di ca. 50.000 m3 ogni anno), hanno solo in parte tamponato l’erosione apicale del delta che, in pochi anni ha portato alla distruzione di buona parte delle splendide dune litorali. fermo restando che questo processo di adattamento della foce alle nuove condizioni ambientali non sembra essersi concluso, e quindi che la vigente situazione può perdurare nel tempo e d’altro canto, permane la necessità di garantire il passo marittimo alla foce di questo importante fiume, si ritiene che senza risagomare e approfondire esageratamente l’alveo, con prevedibili conseguenze sulle sponde e sull’asta terminale del fiume, i materiali idonei a bilanciare l’erosione costiera possono essere ricercati negli accumuli rinvenuti nell’area a ridosso del delta. si ricorda che complessivamente alla foce, in un anno, si registra un bilancio volumetrico positivo di ca. 490.000 m3 di sedimenti di cui circa 90.000 nelle aree di accumulo individuate in questo lavoro. l’asportazione di limitati spessori (ca. 0,5 m) da questi accumuli dovrebbe essere ricompensata a breve termine dall’appurata ricarica naturale, determinata dalla dinamica evolutiva della parte frontale del delta. il prelievo di questo materiale, comunque, deve essere inteso come una semplice integrazione di quello ricavato dalla escavazione del letto del fiume (valutato in circa 68.000 m3 e 166.000 m3 per raggiungere rispettivamente le profondità di 2,5 e 3,5 m ed una larghezza del canale di 100 -150 m). ringraziamenti si ringrazia il comune di lignano sabbiadoro e di san michele al tagliamento per aver finanziato lo studio dell’ogs “indagini meteo-oceanografiche, batimetriche, sedimentologiche e morfologiche finalizzate allo studio dei fenomeni di dinamica costiera lungo i litorali di lignano sabbiadoro e di bibione” e per la loro costante partecipazione in fase di realizzazione dello stesso. un ringraziamento va inoltre alla bibione spiaggia s.r.l., nella persona del geom. g. bittolobon e dei suoi 64 e. gordini, r. marocco & r. ramella collaboratori che hanno fornito un fondamentale supporto logistico durante le fasi di acquisizione dei dati e messo a nostra disposizione tutti gli studi eseguiti in passato. si ringraziano inoltre il personale dell’istituto nazionale di oceanografia e di geofisica sperimentale – ogs di trieste che, a vario titolo, ha offerto contributi utili alla stesura del presente lavoro: un caldo ringraziamento va a m. deponte, r. romeo e n. zanette (gruppo gea), f. donda (gruppo gepa), r. nair (gruppo cto) e p. paganini (gruppo carst). un ringraziamento profondamente sentito va all’”anonimo” revisore della rivista che con i suoi puntuali, motivati e molto pertinenti suggerimenti ha migliorato di molto l’articolo inviato alla stampa. bibliografia a s h l e y g. m., s y m p o s i u m c h a i r p e r s o n (1990) classification of large-scale subaqueous bedforms: a new look at an old problem. jour. of sedim. petrol., 60, 1, 160 -172. brambati a. (1970) provenienza, trasporto e accumulo dei sedimenti recenti nelle lagune di marano e di grado e nei litorali tra il f. isonzo e tagliamento. mem. soc. geol: ital., 9 (4), 281-329. b r a m b a t i a. (1985) morfologia del delta del f. tagliamento e delle sue spiagge. in “raccontare lignano”, benvenuto edit. brambati a. (1987) studio sedimentologico e marittimo-costiero dei litorali del friuli venezia giulia. servizio idraulica della regione friuli venezia giulia, pp. 67. brambati a., catani g., marocco r. (1977) indagini sedimentologiche sulla spiaggia sottomarina dell’adriatico settentrionale tra i fiumi brenta e tagliamento. boll. soc. geol. it., 96, 69-86. brambati a., catani g., lenardon g., marocco r. (1982) rilievi sul litorale da monfalcone alla foce dell’ adige. c.n.r., p.f. “conservazione suolo”, s.p. “dinamica dei litorali”. tipografia nazionale. brambati a., venzo g.a. (1967) recent sedimentation in the northern adriatic sea between venice and trieste. st. trent. sc. nat., sez. a, 44(2), 479-493. capobianco m., hamm l., silva p. (1999) interventi di ripascimento nelle coste europee: ricadute a livello italiano. studi costieri, 1, 3-12. carobene l. (1978) analisi morfologica quantitativa delle spiagge dell’alto adriatico tra monfalcone e lignano. boll. soc. geol. it., 97, 131-164. carobene l., brambati a. (1975) metodo per l’analisi morfologica quantitativa delle spiagge. boll. soc. geol. it., 94, 479-493. catani g., lenardon g., marocco r., tunis g. (1982) rapporto sulle ricerche morfologiche e sedimentologiche effettuate nel 1976 nella spiaggia modello di valle vecchia (venezia). boll. soc. adriat. sc., lxvi, 73-103. catani g., marocco r. (1976) considerazioni sulle caratteristiche mareografiche e anemografiche a san nicolò di lido, runta tagliamento e grado. quaderni della ricerca scientifica, 92, 21-25. catani g., marocco r., brambati a., carobene l. & lenardon g. (1978) indagini sulle cause dell’erosione nel tratto orientale del litorale di valle vecchia (caorle, adriatico settentrionale). mem. soc. geol. it., 19, 399-405. de girolamo p., cecconi g., noli a., maretto g.p., contini p., (1999) monitoraggio della spiaggia di cavallino. studi costieri, 1, 13-25. fontolan g. & sartori di borgoricco m. (2000) caratteri morfodinamici e sedimentologici della bocca lagunare di s. andrea (laguna di marano). estratto da: la ricerca scientifica per venezia vol. ii, tomo ii, 983-991. fontolan g (2004) la fascia costiera, capitolo 4. xi. estratto da: geomorfologia della provincia di venezia (note illustrative della carta geomorfologica della provincia di venezia). esedra edit., pp. 514. gordini e., marocco r. & vio e. (2002) stratigrafia del sottosuolo della “trezza grande” (golfo di trieste, adriatico settentrionale). gortania, 24, 31-63. gordini e., caressa s., marocco r. (2003) nuova carta morfo-sedimentologica del golfo di trieste (da punta tagliamento alla foce dell’isonzo). gortania, 25, 5-30. gordini e., marocco r., tunis g., ramella r. (2004) i depositi cementati del fondale del golfo di trieste (adriatico settentrionale): distribuzione areale, caratteri geomorfologici e indagini acustiche ad alta risoluzione. il quaternario, 17 (2/2), 555-563. hayes m.o. (1980) general morphology and sediment patterns in tidal inlets. sed. geology, 26, 139-156. king c.a.m. (1972) beaches and coasts, (2nd ed). edward arnold, london, pp. 570. marocco r. (1988) considerazioni sedimentologiche sui sondaggi s19 e s20 (delta del f.tagliamento). gortania, 10, 101 –120. marocco r. (1989) evoluzione quaternaria della laguna di marano (friuli venezia giulia). il quaternario, 2, 125137. marocco r. (1991) evoluzione tardopleistocenica-olocenica del delta del f. tagliamento e delle lagune di marano e grado, (golfo di trieste). il quaternario, 4(1b), 223-232. marocco r., pessina m. (2000) il rischio litorale nell’area circumlagunare del friuli venezia giulia. gortania, 17, 5-35. passega r. (1964) grain size representation by cm patterns as a geological tool. journ. sed. petr. 34, 830-847. vischer g. s. (1969) grain size distribution and depositional processes. journ. sed. petr. 39, 10741106. ramella r., viezzoli d., gordini e., codiglia r., romeo r., deponte m. (2004) indagini meteo-oceanografiche, batimetriche, sedimentologiche e morfologiche finalizzate allo studio dei fenomeni di dinamica costiera lungo i litorali di lignano sabbiadoro e di bibione. istit. naz. di oceanogr. e di geofis. sperim. di trieste. rel-28/2004 oga 8. zunica m. (1971) ricerche sulle variazioni delle spiagge italiane – le spiagge del veneto. consiglio nazionale delle ricerche, tipografia antoniana, padova. pp. 141. 65 ms. ricevuto il 17 gennaio 2006 testo definitivo ricevuto il 31 maggio 2006 ms. received: january 17, 2006 final text received: may 31, 2006 dinamica morfologica del litorale ... imp.de waele et al. geosites and landscape evolution of the tacchi: an example from central-east sardinia jo de waele, felice di gregorio, roberto follesa & giuseppe piras department of geology, via trentino 51, 09127 cagliari e-mail: geoam@unica.it abstract: j. de waele et al., geosites and landscape evolution of the tacchi: an example from central-east sardinia. (it issn 03943356, 2005). the tacchi area is a landscape unit located to the south of the gennargentu mountains in the central-eastern part of sardinia, mainly characterised by table-like carbonatic mesozoic mountains, locally named "tacchi", unconformably overlaying a paleozoic peneplain constituted of cambro-silurian silty and sandy shales. the tacchi are the result of a complex geologic history, deriving from a unique and widespread jurassic carbonatic cover that was split up in clods due to epirogenetic movements, faulted, uplifted or lowered and successively eroded and isolated by fluvial processes. the palaeo-geography and the evolution of this landscape can be explained using several different geosites of the area, such as the san giorgio gorge, the su marmuri cave and the monte tisiddu tacco that, united in a network of geosites, can bring to an improvement of the tourist offer of this interesting area. besides these geosites many other places of geological interest such as the riu pardu river and its abandoned villages of gairo vecchio and osini vecchio (partially destroyed by phenomena of hydrogeologic hazard during the xxth century and especially following an exceptional rainfall in october 1951), several waterfalls and travertine deposits can be mentioned, completing an already rich and varied landscape. the project aims to the conservation of the geodiversity and the multiple valences present in the territory, and comprises the valorisation of the sites of geological interest in line with the principles of a sustainable development. this valorisation foresees the realisation of a local network of geosites connected to the system of natural monuments instituted by the regional law 31/1989, the arrangement of equipped pathways, the elaboration of explicative documents and panels in which geology, geomorphology, karst landscape, biology, archaeology and human settlements and processes are described. some panels will be focalised on the reading of the landscape and its evolution (lecture du paysage) in which geological, geomorphological and environmental aspects collimate to form an educational model of great suggestion. this proposal of valorisation of these geosites, grouped in a network, could well be applied to other areas, and the authors hope that the regional and local stakeholders will, in the near future, participate in the geo-environmental preparation of their territory, giving an important service to the many tourists that come and visit the tacchi area. riassunto: j. de waele et al., geositi e evoluzione del paesaggio dei tacchi: un esempio dalla sardegna centro orientale. (it issn 0394-3356, 2005). l'area dei tacchi è un'unità di paesaggio situata a sud del massiccio del gennargentu (sardegna centro-orientale), caratterizzata dalla presenza di altopiani carbonatici mesozoici, conosciuti con il nome locale di "tacchi" o "tònneri", che coprono in discordanza il penepiano paleozoico costituito da metarenarie e metasiltiti di età ordoviciano-cambriana. i tacchi sono il risultato di una complessa evoluzione geologica e derivano da un'unica ed estesa copertura carbonatica giurassica suddivisa in vari frammenti a seguito di movimenti epirogenetici plio-pleistocenici dai quali vennero fratturati, sollevati o abbassati e successivamente erosi e isolati da processi fluviali, gravitativi e meteorici. la paleogeografia e l'evoluzione di questi paesaggi possono essere spiegate in maniera eloquente osservando diversi geositi di questa regione, quali la gola di san giorgio, la grotta di su marmuri e il tacco di monte tisiddu che, collegati a rete possono creare un forte motivo di richiamo per un turismo naturalistico e culturale per questa regione dell'interno della sardegna. oltre a questi geositi il territorio contiene altri validi temi di interesse geologico e geomorfologico come la valle del riu pardu e i suoi villaggi abbandonati di gairo ed osini vecchio (parzialmente distrutti da frane avvenute nel xx secolo e soprattutto dopo le forti piogge nell'ottobre del 1951), diverse cascate temporanee e depositi di travertino o di terre rosse di decalcificazione e valli sospese che completano il richiamo verso questo paesaggio di per sé già ricco e vario. la presente ricerca ha come obiettivo la conservazione della geodiversità e delle molteplici valenze di questo territorio e si propone la valorizzazione dei geositi di maggiore interesse in linea con i principi dello sviluppo sostenibile. tale valorizzazione prevede la realizzazione, d'intesa con le autorità locali, di una rete locale di geositi connesso con il sistema dei monumenti naturali istituiti dalla legge regionale 31/1989, la costruzione di sentieri equipaggiati, l'elaborazione di cartografia tematica e pannelli esplicativi nei quali geologia, geomorfologia, paesaggio carsico, fauna, flora ed archeologia vengono illustrati in forma chiara ed accessibile secondo i criteri di una corretta divulgazione scientifica. in particolare alcuni di questi pannelli saranno focalizzati alla lettura del paesaggio nella quale gli aspetti geologici, geomorfologici ed ambientali collimino a delineare un modello evolutivo di notevole interesse per l'educazione ambientale e nello stesso tempo di grande suggestione dal punto di vista percettivo. la proposta di valorizzazione di tali geositi, raggruppati in una rete, è concepita per integrarsi con l'insieme dei beni geografico-fisici presenti nelle aree limitrofe. tutto questo potrà contribuire a fornire un servizio importante ai numerosi turisti che visitano le coste e che possono trovare nei paesaggi dei tacchi itinerari geotematici di grande interesse. keywords: tacchi, karst, jurassic, dolomitic limestones, geosites, ogliastra. parole chiave: tacchi, carso, giurese, calcari dolomitici, geositi, geoturismo, sardegna. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 213-222 the area of ulassai and osini, in the central-eastern part of sardinia. the three chosen sites are the san giorgio gorge, the su marmuri show cave and the monte tisiddu taccu (fig. 1). aside the description of these geological monu1. introduction in this study, performed in the framework of the national project on geomorphological sites, the authors describe the three most important geosites of 214 j. de waele et al. fig. 1 site orientation. area di ricerca. ments the authors propose the conservation of the multiple valences present in the territory, comprising the valorisation of the sites of geological interest in line with the principles of a sustainable development, also through the realisation of a local network of geosites connected to the system of natural monuments instituted by the regional law 31/1989. this proposal of valorisation of these sites of geological and geomorphological interest, grouped in a local network, could well be applied to other areas ending up with the realisation of a regional system of geosites, and the authors hope that the regional and local stakeholders will, in the near future, participate in the correct geo-environmental management of their territory, giving an important service to the cultural education of the local people and to the many tourists that come and visit the tacchi area and the central-eastern coast of sardinia. 2. methodology geosites and geomorphosites have in some way been recognised as cultural heritage by the “convention of the protection of world’s culture and nature” signed by almost 160 countries and adopted by unesco during the general conference of paris in 1972. this convention gave also birth to the world heritage list of those sites that have “exceptional universal value” from a historical, artistic or scientific point of view. from the end of the 70’s beginning of the 80’s the first inventories of “naturalistic sites” are produced in italy. in this first phase, that can easily be defined preliminary, the study and the cataloguing of geological sites does not have well defined and univocal rules. in 1991 the first european meeting on geosites is held at digne-les-bains (france) during which the “declaration of rights of the earth’s memory” is presented. in the same occasion the methodology for the systematic survey of geological and geomorphological sites on a regional scale is also proposed by barca & di gregorio (1991) with the aim to assure a uniform study and evaluation of such sites. at this scope a file sheet is proposed that is subdivided in four sections: 1) identification, 2) main and integrative parameters of evaluation, 3) degree of scientific and historic-cultural importance, 4) state of use and tutelage. the file sheet is also characterised by the presence of an extract of topographical map and further information on the geographical location. the authors suggest to arrive at a objective way of survey that do not take too much into account the aesthetic criteria normally used in describing natural sites. contemporary casto et al. (1991) produce a type of sheet file used for the cataloguing of geosites and geomorphosites in the provinces of rome and rieti. this sheet file, even though containing a precise location of the described sites and containing also two new elements, such as photographs of the site useful to evaluate modification and or destruction, and a brief description, seems to be too subjective and too dependant on the surveyor (marchetti, 1999; poli, 2003). from the second half of the 90’s the studies and the methodologies continuously improved and also on a national level starts to form the idea of making a uniform methodology and to construct a sheet file based on the positive earlier experiences made in various italian regions. the new sheet files for identification and classification are conceived and realised in order to be inserted in gis systems, in the framework of regional, national and international projects for geosites census. since 1996 the international union of geological sciences (iugs) started the geosites research program in the framework of unesco (wimbledon, 1996). finally, in august 2001, during the ivth international conference of the international association of geomorphologists, the working group “geomorphological sites: research, assessment and improvement” has been instituted, taking experience from the italian national cofin project "geosites in the italian landscape: research, evaluation and valorisation". it is in the framework of all these activities that the term “geomorphosites” has been coined (panizza, 2001) and that new methodologies for cataloguing have been proposed (carton et al., 2003). a sheet file elaborated by the agency for the protection of the environment and territory (apat, former national geologica service) and by the centre for documentation of geosites of the university of genoa, still under experimentation, has been used in this paper. this sheet file is subdivided in fourteen sections further subdivided in sub-sections, and accompanied by a second socalled “specialistic” sheet file. the presence of sub-sections in most of the sections enhances the comprehension of the geosites giving a more detailed information. this new type of sheet file, a part of being the most recent and most developed one, is also the one the better satisfies the requirement both for the analysis and the input of geomorphosite data, and has also been adopted for the surveying of sites in sardinia. 3. geology of the tacchi region the tacchi area is a landscape unit located to the south of the gennargentu mountains in the central-eastern part of sardinia. this unit is mainly characterised by table-like carbonatic mesozoic plateaus, locally named "tacchi", overlaying with 215geosites and landscape ... an unconformity the palaeozoic basement constituted of middle cambrian-ordovician quartzitic-micaceous metasandstones, quartzites, quartzitic phyllites and metasiltstones (gennargentu formation) peneplained during permian-triassic (fig. 2). this long continental period is clearly identified by the local presence of ferruginous phyllites with limonite nodules generally named "ferro dei tacchi", in the past cultivated for the iron content (marini, 1984). the beginning of the jurassic succession is characterised by a more or less well preserved succession of continental fluvial, delta and lacustrine sediments composed of a quartzite conglomerate, sandy and clayey lenses and, in some places, containing lignite seams or clays with vegetal remains (barca & palmerini, 1973; fazzini et al., 1974). according to dieni & massari (1985) these sediments are comparable to the complete succession described at genna selole and attributed to bajocian-bathonian (genna selole formation). palynological studies of these sequences also suggest the age of the black clays with plant remains to be bajocian-bathonian (del rio, 1985). this continental fig. 2 stratigraphic column of the sedimentary sequence of the tacchi in central-east sardinia. colonna stratigrafica della sequenza sedimentaria dei tacchi nella sardegna centro-orientale. 216 j. de waele et al. fig. 3 geological and geom o r p h o l o g i c a l map of the study area with the three geosites. carta geologica e geomorfologica dell'area di studio con i tre geositi. 217geosites and landscape ... 218 j. de waele et al. sequence is immediately followed by a marine succession of dolomitic limestones, in the lower part disposed in well stratified decimetric and metric beds and upwards becoming more massive, upon which are locally preserved about 30 meters of white coralline and oolithic limestones for a total thickness of over 300 meters. recently the lower dolomitic succession has been attributed to the dorgali formation, mostly of bathonian-callovian age, while the uppermost more calcareous part represents sediments of the monte tului and monte bardia formations of calloviankimmeridgian age (barca & costamagna, 2000, barca et al., 2000a; 2000b). this unique and widespread jurassic carbonatic cover emerged form the sea at the end of mesozoic and during tertiary the landscape started evolving with the formation of valleys with prevalent direction nne-ssw that eroded the surrounding palaeozoic mountains. these palaeo-valleys are still recognisable on top of many tacchi where large closed depressions contain remnants of fluvial deposits with metamorphic and quartzite elements (e.g. polje of san giorgio) and suspended valleys occur along the borders of the tacchi. towards the end of tertiary the fluvial erosion of the palaeozoic metamorphosed sediments, enhanced by the epirogenetic movements of the alpine orogeny, started cutting the dolomitic limestone plateau in several separated blocks along the major tectonic directions (nnw-sse, nne-ssw and e-w), causing an inversion of relief. from this period to now the individual tacchi started evolving separately and the karst features show slight differences even between neighbouring table-mountains. from a geomorphological point of view the tacchi of osini and ulassai are mainly characterised by multiple karstic forms such as sinkholes, dry valleys, larger depressions (macrodolines), caves, stone forests and other spectacular r u i n l i k e e r o s i o n a l k a r s t i c forms; grykes, solution pans, karren and other minor karst phenomena are less developed (marini & ulzega, 1973; bianco & de waele, 1992; ardau & de waele, 1999; bartolo et al., 1999). the valleys that divide the tacchi, some of which have rapidly evolved since pliocene (ulzega & marini, 1977), are characterised by unstable flanks where landslides have repeatedly occurred in concomitance with heavy rainfalls (e.g. rio pardu) (maxia et al., 1973; ciccu et al., 1994; ginesu, 1999). 4. the geosites the most typical landform of the region is the so-called taccu or tonneri, table-like carbonatic mountain being the result of the geomorphologic processes that have changed the landscape since tertiary. these geomorphic testimonies constitute the remains of a continuous dolomitic limestone platform that covered most part of central-east sardinia, cut in many independent outcrops situated at varying heights by tectonic movements and erosion and forming a typical example of inversion of relief. at the basis and along the borders of these mountains, in some places, the jurassic transgression sediments of the genna selole formation can be observed and the traces of the ancient excavations for lignite can still be seen along the path that runs at the basis of tisiddu. on the contact of dolomitic limestones and palaeozoic basement many karst springs are situated, most of which are used for the orchards or for public fountains (ardau et al., 1993). in figure 3 a geological and geomorphological map of the region is given in which the three geosites are clearly reported. one of the most typical tacchi is monte tisiddu near ulassai; this carbonatic plateau, with a surface of about 1.5 km2 and walls of 50 to 100 m height, is controlled by the forestry department, and shows interesting and spectacular karstic landforms such as sinkholes, caves etc. (bianco & de waele, 1992) (fig. 4). there are only four pathways that allow to ascend the carbonatic plateau, while along almost the entire perimeter of tisiddu vertical walls form a natural inaccessible barrier. these ancient tracks can be followed by hikers and allow to make walks of scientific and didactic interest in a mostly uncontaminated nature and with diversified and unusual panorama's on the underlying riu pardu and riu ulassai valleys and on the villages of ulassai and jerzu. once on tisiddu the landfig. 4 monte tisiddu tacco: a panoramic view from bruncu cococcia towards the northwest: on the first plan to the left the vertical walls of bruncu casteddu (monte tisiddu) and in the background the other smaller tacchi of jerzu, all covering the palaeozoic basement profoundly incised by the tertiary and quaternary valleys (photo jo de waele). tacco di monte tisiddu: vista panoramica da bruncu cococcia verso nordovest; in primo piano sulla sinistra si vedono le pareti verticali di bruncu casteddu, mentre sullo sfondo si notano gli altri piccoli tacchi di jerzu, che coprono anch'essi il basamento paleozoico intensamente inciso da valli terziarie e quaternarie (foto jo de waele). scape is dominated by karstic landforms such as dolines, dry valleys, caves and karst pinnacles. from the highest top of the mountain (bruncu matzeu, 957 m a.s.l.) a spectacular and widespread view stretches from the tyrrhenian sea to the gennargentu mountains, while the nearby tacco of ulassai dominates the riu pardu valley. the river pardu flows along a nw-se alpine fault and deeply cuts the palaeozoic basement. this rapid deepening by erosion is related to the plio-quaternary uplifting of the whole area that also caused the capture of rio pardu approximately 3 km downstream of ulassai. this capture determines an abrupt change of direction from nw-se to ne-sw. the rapid geomorphologic evolution of the valley has caused mass movements, mainly along tension cracks, provoking a whole generation of quaternary landslides (ulzega & marini, 1977; arisci et al., 2000). the most impressive of these tension cracks is the san giorgio gorge, across which passes a road that connects the village of osini with the carbonatic high plateau rich in karst forms, interesting endemic flora and archaeological remains (fig. 5). the san giorgio gorge forms the natural gateway to the plains of the karstic tacco of ulassai and is one of the island's natural monuments instituted by the regional law n°31/1989. in this narrow gorge, wide only 8 m in some places for a height of 40 m, have been found archaeological remains of a roman settlement. some pathways lead up into the mountain to the eastern flank of this tension crack from where the panorama dominates the entire riu pardu valley with its abandoned villages of gairo and osini (partially destroyed by landslides during the xxth century and particularly after exceptional rainfalls in october 1951), the reconstructed new villages and ancient and recent landslides and rockfalls. a couple of hundreds of meters to the north, along the high dolomite walls of the taccu, a suspended valley testimonies an ancient late-tertiary hydrography. but the most important proof of an ancient drainage basin on the tacco is the enormous sinkhole and underground river passage of the su marmuri cave near ulassai, open to public from april to october and accounting for more than 20,000 visitors/year (fig. 6). the cave entrance is characterised by a collapse doline which has uncovered a very big natural tunnel. after a descent of almost 40 meters along a stairway constructed in the late 50's the cave passage becomes horizontal and is characterised by a angular development caused by the intersection of fractures along which the underground river has eroded forming this gigantic tunnel. the enormous natural underground river passage of su marmuri ends deep into the carbonatic plateau after 219geosites and landscape ... fig. 5 san giorgio gorge: spectacular view of the dolomite peak at the centre of the gorge, isolated by tension cracks, around which the tarmac road that connects the village of osini with the karstic plateau of tacco of ulàssai turns (photo jo de waele). la gola di san giorgio: vista spettacolare del picco dolomitico che si erge al centro della gola, isolato da tension cracks, attorno al quale gira la strada asfaltata che collega l'abitato di osini con l'altopiano carsico del tacco di ulàssai (foto jo de waele). a total length of almost 900 meters. in the median part of the cave the floor is constituted of thousands of rimstone pools (fig. 6), followed by a giant room with impressive flowstones, stalagmites and stalactites. close to the entrance lay two fresh-water lakes nearby which hibernate more than 10,000 bats (miniopteris schreibersi natt.) during winter. besides this colony of bats, among the greatest known on the island, the cave is very important for its cave dwelling fauna with rare endemic arthropods such as the beetle ovobathysciola gestroi fairmaire (the first troglobius animal discovered by raffaello gestro in sardinia at the end of the 19th century) and the chilopod lithobius doderoi silvestri, both of which are typical of the tacchi region (bartolo et al., 1983; de waele, 1996; bartolo et al., 1999). 220 fig. 6 plan of the su marmuri cave that takes its name from the characteristic concretioning (marble), with the environmental monitoring system proposed by ardau & de waele (1999) (survey by gruppo speleo-archeologico nino businco ulàssai). pianta della grotta di su marmuri con il sistema di monitoraggio proposto da ardau & de waele (1999): la grotta prende il nome dall'abbondante e massiccio concrezionamento. (rilievo dal gruppo speleo-archeologico nino businco ulàssai). j. de waele et al. 5. proposal of conservation and valorisation monte tisiddu, the gorge of san giorgio and the su marmuri cave constitute all together an extraordinary example of the tertiary-quaternary landscape evolution of the mesozoic carbonatic platform that characterise the central eastern part of sardinia: the first, with its dolines, the dry valleys and the karst pinnacles as a testimony of a well developed and mature surface karst; the second representing the tectonic and gravitational phenomena and correlated to the fragmentation of the borders of the forming carbonatic plateaus and the third emblematically testifying the underground karst evolution that started before the fragmentation of the emerged carbonate platform. to protect and to valorise these three geosites the authors propose the creation of a local network of geological monuments, connected to a regional system that was started with the institution of the regional natural monuments of the regional law 31/1989. for these purposes a program of detailed geological-stratigraphical and geomorphological survey has been foreseen that aims to put in evidence their intrinsic characteristics, essential for their appropriate valorisation and a management compatible with their effective carrying capacity, in particular for the su marmuri cave where a meteorological study will monitor the subterranean environment. after this phase, in collaboration with the local authorities, illustrative material will be prepared (booklets, cd rom, synthetic thematic maps, etc.) in order to document the elements of interest of these geological landscapes and geosites and, ultimately, a series of explicative panels, containing the educational information, and signals will be positioned to enable their correct utilisation. aside these initiatives, anyhow, for some of these geosites (monte tisiddu, gorge of san giorgio) it will be necessary to enforce the measures of protection of the territory and the landscape, and also the formation of local guides that are prepared to explain the interest and the importance of these sites and of the network of geomorphological sites in a regional and in a national context. acknowledgements this research has been performed in the framework of the national project cofin 2001-2003 "geositi nel paesaggio italiano" which local research group is co-ordinated by 221 fig. 7 su marmuri cave: "galleria delle vaschette"(passage of the gours) in the central part of the cave has developed along a nw-se fracture, is characterised by vertical and rectilinear walls widened by underground fluvial erosion processes, and its floor is at present completely covered with thousands of gours filled with water, some of which still contain cave pearls (photo gabriela pani). la grotta di su marmuri: "galleria delle vaschette", nella parte centrale della cavità è impostata su una frattura no-se e si caratterizza per le pareti rettilinee e verticali allargate da processi d'erosione fluviale. il pavimento è completamente ricoperto da migliaia di vaschette riempite d'acqua, alcune delle quali contengono perle di grotta (foto gabriela pani). geosites and landscape ... prof. antonio ulzega and prof. felice di gregorio of the university of cagliari. the authors would like to thank andré ozer and an anonymous referee for their useful comments and advice. references ardau f. & de waele j. (1999) geosites of the tacchi area (central-east sardinia, italy) in: d. barettino, m. vallejo & e. gallego (eds.), towards the balanced management and conservation of the geological heritage in the new millenium, madrid, pp. 87-93. ardau f., bianco l., de waele j. & vernier a. (1993) studio dell'idrogeologia e caratterizzazione idrochimica delle acque del tacco di ulàssai (sardegna centro-orientale) atti 3° congr. naz. dei giov. ric. di geol. appl., potenza 28-30 ottobre 1993, geologia applicata e idrogeologia, 27, pp. 27-34. arisci a., di gregorio f., follesa r. (2000) cartography in areas at risk: the example of the alluvial plain of the pelau river (central-east sardinia) – atti x congresso nazionale di geologia, roma 7-10 december 2000, pp. 535-544. barca s. & costamagna l.g. 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(1974) ricerche sul verrucano 2. le successioni basali dei "tacchi" tra escalaplano e jerzu (sardegna sud-orientale) bollettino società geologica italiana, 93, pp. 221-243. ginesu s. (1999) aspetti del paesaggio fisico in un microcontinente poddighe (ed.), sassari, 164 pp. marchetti m. (1999) il censimento dei “beni geologici” in: g. poli (ed.), geositi, testimoni del tempo, regione emilia-romagna, servizio paesaggio, assessorato alla programmazione, ed. pendragon, bologna, pp. 69-87. marini c. (1984) le concentrazioni residuali post-erciniche di fe dell'ogliastra (sardegna orientale): contesto geologico e dati mineralogici rendiconti società italiana di mineralogia e petrologia, 39 (1), pp. 229-238. marini a. & ulzega a. (1973) osservazioni geomorfologiche sul tacco di ulassai rendiconti seminario facoltà scienze università di cagliari, 47 (12), pp. 192-208. maxia c., ulzega a. & marini c. (1973) studio idrogeologico dei 83 dissesti nel bacino del rio pardu (sardegna centro-orientale) pubblicazione dell'istituto di geologia, paleontologia e geografia fisica, 121(12), 9 pp. poli g. (2003) dalla stanza delle meraviglie alle meraviglie della terra in: s. piacente & g. poli (eds.), la memoria della terra. la terra della memoria, l’inchiostro blu ed., bologna, pp. 28-40. ulzega a., marini a. (1977) l’évolution des versants dans la valée de rio pardu. zeitschrift fur geomorphologie n.f., 21 (4), pp. 466-474. wimbledon w.a.p. (1996) geosites a new conservation initiative episodes, 19, pp. 87-88. 222 j. de waele et al. imp.scicchitano_monaco grotte carsiche e linee di costa sommerse tra capo santa panagia e ognina (siracusa, sicilia sud-orientale) giovanni scicchitano & carmelo monaco dipartimento di scienze geologiche, università di catania, corso italia, 55, 95129 catania email: cmonaco@unict.it; gscicchi@unict.it riassunto: scicchitano g. & monaco c., grotte carsiche e linee di costa sommerse tra capo santa panagia e ognina (siracusa, sicilia sud-orientale). (it issn 0394-3356, 2007). la zona costiera della sicilia sud-orientale compresa tra capo s. panagia e ognina (siracusa) è caratterizzata dalla presenza di numerose paleo-linee di costa sollevate, legate a stazionamenti del livello del mare durante il tardo quaternario. esse sono rappresentate da falesie e spianate d’abrasione scavate su una successione calcarea miocenico-pleistocenica e sono collegate spesso a forme di erosione di tipo carsico (grotte, canali, sifoni etc.) al cui interno sono stati ritrovati numerosi speleotemi (stalattiti, stalagmiti, concrezioni cipollari). sotto il livello del mare si riscontrano gli stessi caratteri morfologici, in quanto i fondali sono caratterizzati da almeno due paleo-falesie marine, una tra -9÷12 m e -20÷22 m l’altra tra -20÷25 m e -40÷45 m, verso cui si aprono cavità sommerse, sifoni e canali, ospitanti a volte speleotemi continentali fossilizzati. il presente lavoro consiste nel rilevamento dettagliato dei fondali marini antistanti la linea di costa tra capo s. panagia e ognina, al fine di ricostruire l’andamento spaziale e la continuità degli elementi morfologici sommersi e di stabilirne la possibile genesi ed evoluzione temporale. questi elementi morfologici possono essere interpretati come testimonianze di stazionamenti pleistocenici del livello del mare, ora sommersi a causa della veloce risalita olocenica del livello del mare. abstract: scicchitano g. & monaco c., karstic caves and submerged paleo-shorelines in the coastal area between capo santa panagia and ognina (siracusa, south-eastern sicily). (it issn 0394-3356, 2005). the aim of this work is the detailed survey of the submerged area in front of the shoreline between capo s. panagia e ognina (siracusa), in order to reconstruct the lateral extension and the continuity of the submerged morphological elements and to define their genesis and temporal evolution. this coastal stretch is characterized by the occurrence of several raised paleo-shorelines, related to late quaternary high-stands. they are represented by cliffs and abrasion platforms carved on a miocene-pleistocene carbonatic succession and are often linked to karstic levels (caves, channels, siphons, etc.). several speleothems, such as stalagmites, stalactites, columns, cave pearls, have been found in the caves. the submerged area is characterized by the same morphological features. the sea-bottom is, in fact, characterized by at least two palaeo-cliffs of marine origin, the shallower one located at depths between -9÷12 m and -20÷22 m, the deeper one located at depths between -20÷25 m and -40÷45 m. the scarp located between -9÷12 m and 20÷22 m is well preserved and shows a continuity of about 20 km. the scarp located between -20÷25 m and -40÷45 m is more discontinuous and steeper. several caves, channels and siphons, characterized by the occurrence of continental fossilized speleothems, have been found along these scarps, probably linked to palaeo-karstic levels. the detailed topographic survey of two caves has been carried out and a stalagmite has been sampled in order to determine its age and to reconstruct the relationships between sea-level rise and vertical tectonic motion of the area. the morphological analysis and the first dating results suggest that the two submerged palaeo-shorelines can be interpreted as the effect of late pleistocene sea level stands. at present they are submerged as a consequence of the sudden holocene sea-level rise. parole chiave: carsismo, paleo-linee di costa, olocene, sicilia sud-orientale. keywords: karstism, paleo-shorelines, holocene, south-eastern sicily. il quaternario italian journal of quaternary sciences 19(2), 2006 187-194 1. introduzione l’area costiera di siracusa in sicilia sud-orientale (fig. 1) è caratterizzata dalla presenza di vari ordini di terrazzi e spianate d’abrasione, che si sviluppano dalla linea di costa attuale sino a diversi chilometri da essa, nonché dalla presenza di varie scarpate morfologiche che, presentando indicatori di livello marino di vario genere (solchi di battente, piattaforme a vermetidi, fori di litodomi) sono state interpretate come paleo-linee di costa legate a stazionamenti del livello del mare durante il tardo quaternario (carbone et al., 1982; di grande & raimondo, 1982; bianca et al., 1999). queste paleolinee di costa sono ubicate al bordo interno di piattaforme d’abrasione marina ed essendo scavate su formazioni calcaree (formazioni di monti climiti e di monte carruba, a.a.v.v., 1986) sono collegate a livelli paleocarsici (ruggieri & amore, 2000; ruggieri & grasso, 2000). le forme prevalenti lungo le paleo-linee di costa emerse dell’ area considerata, come anche lungo le falesie costiere attuali, sono rappresentate da grotte, canali e sifoni al cui interno sono stati ritrovati numerosi speleotemi (stalattiti, stalagmiti, concrezioni cipollari). sotto il livello del mare si riscontrano gli stessi caratteri morfologici, in quanto i fondali sono caratterizzati da numerosi elementi morfologici, tra cui cavità sommerse, sifoni e canali, che possono essere interpretati come testimonianze di antichi stazionamenti del livello del mare ora sommerse a causa della veloce risalita olocenica. questi elementi morfologici sono in genere allineati alla base di piccole scarpate sottomarine. i fondali antistanti le coste siracusane sono infatti caratterizzate da improvvise rotture di pendio, site a profondità diverse, con sviluppo laterale chilometrico 188 g. scicchitano & c. monaco (fig. 2). lungo tali scarpate si aprono numerose grotte sommerse il cui ingresso coincide quasi sempre con la base delle scarpate e al cui interno spesso si ritrovano speleotemi di vario tipo (leonardi, 1994) che denunciano una speleogenesi carsica continentale delle grotte stesse. scopo del presente lavoro è presentare il rilevamento dettagliato dei fondali marini antistanti la costa tra capo santa panagia e ognina (siracusa), al fine di ricostruire l’andamento spaziale e la continuità delle scarpate sommerse e di stabilirne la possibile genesi ed evoluzione temporale. a questo scopo sono state effettuate oltre 50 ore d’immersione lungo tutta l’area, durante le quali è stato eseguito il rilevamento batimetrico e topografico degli elementi riscontrati tramite posizionamento con gps e bussola a puntamento. in particolare, la base delle scarpate sottomarine è stata pedagnata sul fondo dagli operatori subacquei e segnalata in superficie da boe poi rilevate a mezzo di gps interfacciato con eco-scandaglio. inoltre è stato eseguito il rilievo topografico di dettaglio di due grotte che presentano al loro interno speleotemi continentali. infine sono stati campionati alcuni speleotemi su cui sono in corso datazioni assolute con i metodi u/th e radiocarbonio al fine di ricostruire le relazioni tra movimenti tettonici verticali e variazioni del livello del mare fig. 1 schema tettonico del sicilia sud-orientale. il riquadro in basso a sinistra mostra l’area del mediterraneo centrale con il sovrascorrimento frontale dell’orogene (linee con triangoli) e le principali faglie quaternarie (linee con tratti). tectonic sketch map of south-eastern sicily. inset shows the central mediterranean area with the frontal thrust of the orogenic belt (lines with triangles) and main quaternary faults (lines with barbs). (v. alessio et al., 1994; antonioli et al., 1998) nell’area durante il tardo quaternario (dutton et al., in preparazione). 2. inquadramento geologico-morfologico la costa siracusana è ubicata nelle propaggini orientali del plateau ibleo in sicilia sud-orientale e fa parte quindi dell’area d’avampaese dell’orogene siculomaghrebide (fig.1). la successione litostratigrafia affiorante comprende terreni sedimentari ed eruttivi d’età compresa tra il cretaceo e l’attuale (a.a.v.v, 1986). la linea di costa è caratterizzata dalla presenza di due penisole rocciose, di santa panagia e della maddalena (fig. 2), costituite da sedimenti carbonatici organogeni di mare basso di età neogenico-quaternaria, separate da un’ampia baia (porto grande di siracusa), in cui 189grotte carsiche e linee di costa sommerse ... affiorano depositi pelitici pleistocenici e fluvio-costieri olocenici, a sua volta chiusa a nord-est dall’isola di ortigia. gli elementi morfostrutturali più evidenti sono costituiti dall’horst di belvedere-santa panagia, orientato in direzione est-ovest, dal graben pleistocenico di floridia e dall’horst della penisola della maddalena, orientato in direzione nnw-sse (fig. 1). i dati morfologici e geologici, insieme con l’analisi di profili sismici eseguiti lungo l’offshore ionico (bianca et al., 1999; monaco & tortorici, 2000), suggeriscono che la deformazione più recente di questa zona sia rappresentata da un lento sollevamento legato all’attività di una faglia ubicata nell’offshore ionico, con orientazione nnw-sse, che ha riattivato il sistema mesozoico della scarpata ibleo-maltese (fig. 1). l’elemento morfologico principale dell’area in esame è rappresentato da una gradinata di ampie spianate d’erosione d’età pleistocenica, limitate verso monte da evidenti paleo-linee di costa (carbone et al., 1982; di g r a n d e & r a i m o n d o , 1982; b i a n c a , 1999; b i a n c a et al., 1999) che testimoniano i sollevamenti subiti dall’area a causa dell’attività della faglia ubicata offshore. tassi di sollevamento medi di circa 0,6 mm/a sono stati stimati per l’area di siracusa a partire da 400 ka (bianca et al., 1999). nonostante il lento sollevamento, l’area costiera è stata invasa dal mare durante la risalita del livello marino nel corso dell’olocene (l a m b e c k et al., 2004) come testimoniato dalla presenza di numerosi resti archeologici oggi sommersi (scicchitano et al., in preparazione) e da un’analisi di facies su depositi transizionali eseguita poco a nord di siracusa (monaco et al., 2004). 3. morfologia delle aree sommerse i fondali antistanti la costa siracusana sono caratterizzati da almeno due paleo-falesie, una ubicata a profondità tra 9÷12 m e -20÷22 m l’altra tra 20÷25 m e -40÷45 m (fig. 2), verso cui si aprono cavità sommerse, sifoni e canali, ospitanti a volte speleotemi continentali fossilizzati (fig. 3a). la scarpata sommersa tra -9÷12 m e -20÷22 m rappresenta l’elemento morfologico più continuo e meglio conservato dei fondali esaminati. essa si sviluppa con batimetria costante per circa 20 km, con la cresta della scarpata alla profondità media di circa 10 m e la base a circa -20 m fig. 2 carta morfo-strutturale dell’area costiera di siracusa (ubicazione in fig. 1). morpho-structural map of the siracusa coastal area (location in fig. 1). 190 fig. 3 a) speleotemi continentali con incrostazioni marine in una grotta sommersa a profondità di circa -20 m; b) stalattite sulla volta della grotta del plemmirio; c) stalagmite di dimensioni metriche nella terza camera della grotta del plemmirio; d) fase di recupero della stalagmite del plemmirio; e) ingresso principale della grotta delle corvine; f) ingresso secondario della grotta delle corvine; g) colonne su una parete della grotta delle corvine; h) ingresso principale della grotta di san corrado. a) continental speleothems with marine incrustations in a submerged caves at -20 m depth; b) stalactite on the roof of the plemmirio cave; c) 1 m high stalagmite in the third room of the the plemmirio cave; d) sampling of the plemmirio stalagmite; e) main entrance of the corvine cave; f) secondary entrance of the corvine cave; g) columns on a wall of the corvine cave; h) main entrance of the san corrado cave. a) c) e) g) h) f) d) b) g. scicchitano & c. monaco 191 (fig. 2). lungo la scarpata sono state riscontrate una trentina di grotte e cavità, le quali presentano uno sviluppo quasi sempre cunicolare o raramente caratterizzato da ampie stanze comunicanti tramite stretti passaggi o sifoni verticali. da sud verso nord la scarpata è stata cartografata a partire dal punto di coordinate 36°58’27,0”n 15°16’02,0”e antistante il promontorio di capo ognina. qui la scarpata sommersa si mantiene ad una distanza dalla costa di 500 m, mentre verso nord, in corrispondenza di punta asparano, punta arenella e punta milocca (fig. 2), si avvicina a 200÷300 m. in questo settore la scarpata presenta una morfologia a gradinata con pochi tratti verticali e non è stata riscontrata la presenza di grotte o cavità. da punta milocca fino alla punta sud-occidentale della penisola della maddalena (plemmirio) la scarpata sommersa, pur mantenendo le stesse caratteristiche, si avvicina alla linea di costa fino al punto di coordinate 37°00’15,3”n 015°18’44,4”e, corrispondente con l’ingresso della “grotta del plemmirio”, conosciuta anche come “grotta del gymnasium” (leonardi, 1994), ubicato a -22 m di profondità (fig. 2). in corrispondenza della “grotta del plemmirio” la scarpata dista circa 80 m dalla costa e presenta un salto netto da -10,5 m a -22 m, con pareti verticali prive di asperità e senza accumuli di crollo alla base. lungo il ciglio della parete a -12 m si osservano lunghi solchi longitudinali. dalla cima della scarpata verso la costa i fondali si presentano rocciosi e alla profondità monotona di -9/10 m fin quasi a riva dove le falesia è bassa e poco acclive. procedendo verso est, lungo la costa meridionale della penisola della maddalena, la scarpata si presenta continua e sub-verticale, a profondità costante e distante dalla linea di costa fino ad un massimo di circa 120 m. in prossimità del capo murro di porco e per ulteriori 600 m circa verso nord (fig. 2), si avvicina all’alta falesia attuale seguendola quasi parallelamente. lungo la costa nordorientale della penisola maddalena la scarpata prosegue ininterrotta mantenendosi a distanze superiori dalla costa. in prossimità dell’imboccatura del porto grande di siracusa la scarpata scompare al di sotto dei sedimenti trasportati dal fiume anapo (fig. 2) e i fondali portuali si presentano monotoni e poco acclivi anche se talora interrotti da piccoli gradini topografici di pochi metri d’altezza. la scarpata tra -9÷12 m e -20÷22 m riappare in prossimità dell’estrema punta meridionale dell’isola di ortigia (fig. 2). verso nord la scarpata sottomarina si allontana dalla costa fino al punto, distante più di 500 m, in cui è ubicata la “grotta delle corvine” (vedi sotto), per poi riavvicinarsi in prossimità di capo santa panagia. in questo settore la continuità della scarpata viene interrotta da due ampi accumuli di detrito che ricoprono con grossi blocchi i fondali a profondità compresa tra -9 m e -25 m. in questo settore, nonostante i sedimenti detritici tendano a obliterare la scarpata, sono ancora riconoscibili esempi di morfologie carsiche relitte come sifoni verticali ed ampie cavità con all’interno speleotemi a volte di notevoli dimensioni (ad es. grotta di san corrado, vedi sotto). un’altra scarpata sommersa, che si estende a profondità tra -20÷25 m a -40÷45 m, è stata rilevata verso il mare aperto, soprattutto al largo di capo santa panagia, di capo murro di porco e tra punta milocca e capo ognina (fig. 2). questa seconda scarpata non è continua ma intervallata per lunghi tratti da fondali poco acclivi. essa presenta una morfologia sub-verticale e priva di asperità nelle aree di capo santa panagia e capo murro di porco e una morfologia a gradoni lungo la costa che corre tra punta milocca e capo ognina. lungo le pareti di questa scarpata sono state riscontrate numerose cavità, canali, archi e sifoni. a sud-est di capo murro di porco (fig. 2), a circa 100 m di distanza dalla costa, si trova una piccola secca (“secca del capo”) la cui sommità giace alla profondità di -13 m mentre la base tra -40 e -50 m. le spettacolari pareti verticali, ricche di vita e spazzate da forti correnti, formano un’unica scarpata. numerose sono le cavità di origine carsica che si trovano lungo le pareti sud-orientali della secca, principalmente a profondità comprese tra -15 m e -30 m, dove sono stati osservati alcuni speleotemi. 4. cavità carsiche sommerse lungo la scarpata sottomarina ubicata tra -9÷12 m e -20÷22 m sono state riscontate numerose cavità di genesi carsica. la maggior parte di esse sono rappresentate da cunicoli poco profondi ubicati lungo faglie o fratture allargate da processi di corrosione paleocarsica o per opera del mare. numerosi sono anche i sifoni verticali e i canyon sommersi, probabili paleo-incisioni fluviali invase dal mare durante la sua risalita olocenica. la grotta del plemmirio, ubicata a -22 m a sud della penisola della maddalena (fig. 2) e già rilevata da leonardi (1994), rappresenta l’esempio più conosciuto e importante del campo carsico sottomarino al largo della costa siracusana. lunga 80 m, è composta da quattro ambienti a fondo pelitico, ricchi di speleotemi e collegati da stretti passaggi. la volta di passaggio tra il primo e il secondo ambiente è costellata di stalattiti decimetriche (fig. 3b), mentre la volta del secondo ambiente presenta decine di stalattiti di dimensioni variabili da 0,5 m a 2,5 m. il terzo ambiente presenta volte alte fino a 6 m e ospita due stalagmiti alte circa 1 m (fig. 3c), ricoperte da incrostazioni di serpulidi. una delle due stalattiti, ubicata a -20 m, è stata campionata per uno studio di dettaglio (fig. 3d) ed è stata determinata l’età assoluta dei primi organismi incrostanti con il metodo del radiocarbonio (circa 8 ka; dutton et al., in preparazione). al largo della costa della penisola di santa panagia, lungo la scarpata tra -9÷12 m e -20÷22 m, sono state esplorate altre due grotte (grotta delle corvine e grotta di san corrado, fig. 2), ritenute importanti sia per estensione che per la presenza di numerosi speleotemi continentali. di queste cavità sottomarine è stato effettuato il rilievo topografico di dettaglio. 4.1 grotta delle corvine (coordinate 37°04’14,5”n – 015°18’08,8”e) la grotta delle corvine si apre alla profondità di 20,5 m ad est di ortigia (fig. 2). presenta due distinti ingressi (fig. 4) il più ampio dei quali, largo circa 6 m (fig. 3e), collega direttamente con un’ampia camera, mentre quello secondario presenta morfologia cunicolare (fig. 3f). il fondo, coperto da sedimenti pelitici sciolti, si trova a una profondità pressoché costante grotte carsiche e linee di costa sommerse ... 192 tranne il settore finale del lungo corridoio (vedi sez. a – b in fig. 4) dove affiora un pavimento roccioso che risale fino a -14 m. lo spessore dei sedimenti (misurato con sondino d’acciaio) supera i 2 m nella prima camera ma si riduce notevolmente fino a poche decine di cm lungo il corridoio che porta all’ultima camera. l’idrodinamismo all’interno della grotta è molto basso o del tutto assente. le porzioni prossimali alle aperture sono densamente popolate e le pareti incrostate da organismi di vario genere mentre gli ambienti più interni, più selettivi in quanto quasi sciafili, mantengono una bassa densità di popolamento. nella seconda camera staziona un folto branco di corvine, da cui il nome della grotta. diversi gruppi di speleotemi di dimensione molto variabile, costituiti prevalentemente da stalattiti e colonne (fig. 3g), sono ubicati in tutte e tre le camere che compongono la grotta ad una profondità compresa tra -17 m e -14 m. 4.2 grotta di s. corrado (coordinate 37°06’02,7”n – 015°18’17,2”e) la grotta di san corrado (fig. 5) è sita nei fondali prospicienti il capo di santa panagia, a nord di siracusa, e più precisamente nell’area antistante la chiesa di san corrado, da cui prende il nome. anche questa cavità si apre sulla parete della scarpata tra 9÷12 m e -20÷22 m sulla quale si affaccia a -20 m di profondità con quattro aperture distinte, due delle quali ampie (fig. 3h) e le rimanenti a sviluppo cunicolare. le volte sono ampie e riccamente incrostate, il fondo è ricoperto da una coltre detritica sciolta a granulometria arenitica nelle porzioni iniziali fino a pelitica in quelle più interne, dove raggiunge uno spessore di circa 2 m. gli ambienti, anche i più interni, sono sufficientemente illuminati e ospitano insediamenti bentonici. l’idrodinamismo all’interno della grotta è spesso elevato per effetto delle molteplici entrate che si aprono nell’ampia prima camera. in più punti della cavità affiorano sorgenti di acqua dolce che ben si manifestano con aloclini marcati che si riscontrano già a partire da pochi metri dagli ingressi. al suo interno la grotta mostra un ampio corredo di speleotemi costituito da stalattiti, stalagmiti, colonne e concrezioni cipollari, ubicati a profondità variabili da -17 m a -12 m. 5. discussione e conclusioni il rilievo topografico di dettaglio dei fondali prospicienti la costa siracusana ha rivelato la presenza di due scarpate sommerse, la più superficiale ubicata a profondità tra -9÷12 m e -20÷22 m, la più profonda tra -20÷25 m e -40÷45 m. l’andamento sub-parallelo alla linea di costa attuale, la batimetria costante, il collegamento con un paleo-livello carsico, nonché la continuità chilometrica della scarpata superiore provano che si tratti di paleo-linee di costa sommerse. la presenza di fig. 4 rilievo planimetrico e sezione longitudinale della grotta delle corvine. planimetric map and longitudinal section of the corvine cave. fig. 5 rilievo planimetrico e sezione longitudinale della grotta di san corrado. planimetric map and longitudinal section of the san corrado cave. g. scicchitano & c. monaco grotte carsiche di chiara origine continentale lungo le due scarpate suggerisce infatti che esse abbiano rappresentato i livelli di base di sistemi paleo-carsici relativi a fasi di stazionamento del livello del mare. la profondità nominale delle due paleolinee di riva viene qui fissata con la base delle scarpate sottomarine, rispettivamente a -20÷25 m e -40÷45 m. considerato il discreto sviluppo, è difficile che le paleo-linee di costa e i relativi sistemi carsici si siano sviluppati durante il breve lasso di tempo della risalita olocenica che è stata piuttosto rapida e non intervallata da stazionamenti del livello del mare (v. lambeck et al., 2004). le due paleo-linee di costa devono essere quindi più antiche e vengono qui riferite ad un generico pleistocene. alcune considerazioni ci permettono di assegnare queste paleo-linee a stazionamenti abbastanza recenti. la buona preservazione delle scarpate, in particolare di quella superiore, suggerisce che esse non abbiano subito l’effetto erosivo di ripetute oscillazioni eustatiche. inoltre dato il modesto tasso di sollevamento tettonico dell’area (0,6 mm /a; bianca et al., 1999), si può supporre che queste linee di costa possano essere riferite agli stazionamenti del mis 3 e che siano state sollevate dalla profondità di circa 40÷60 m che contraddistingue i picchi dello stadio mis 3 (waelbroeck et al., 2002) alla loro attuale profondità nel corso degli ultimi 60÷40 ka. la presenza di speleotemi all’interno di grotte sommerse ha dunque fornito la conferma che i sistemi paleo-carsici collegati con le due paleo-linee di costa si siano sviluppati in ambiente continentale durante il pleistocene superiore per poi essere sommerse e fossilizzate per effetto dalla veloce risalita del mare olocenica (lambeck et al., 2004). la datazione preliminare degli organismi incrostanti prelevati alla base di una stalagmite ubicata all’interno della grotta del plemmirio a -20 m di profondità (dutton et al., in preparazione) indica che l’ultima risalita del livello marino abbia iniziato a sommergere la scarpata superiore circa 8.000 anni fa. al fine di dettagliare con maggiore precisione le variazioni relative del livello del mare e ottenere dati più certi sulla genesi ed evoluzione della grotta e della relativa linea di costa durante il quaternario sono state avviate, in collaborazione con la research school of earth science di canberra–australia, analisi di datazione assoluta, con i metodi u/th e radiocarbonio, su varie porzioni della suddetta stalagmite e di altri speleotemi campionati in grotte carsiche ubicate alla base delle due scarpate sottomarine. la datazione delle concrezioni marine e dei livelli continentali all’interno di speleotemi a livelli marini-continentali (alessio et al., 1994; antonioli et al., 1998) rappresenta infatti un eccellente metodo per la ricostruzione delle variazioni del livello del mare oltre che per lo studio del paleoclima. ringraziamenti si ringraziano i due anonimi referee per i commenti e i suggerimenti che hanno consentito di migliorare il lavoro. si ringraziano inoltre luciano tinè e fabio esposito e tutti i ragazzi della scuola subacquea "punto sub" di siracusa per la collaborazione alle operazioni subacquee. bibliografia a.a-v.v. (1986) carta geologica del settore nordorientale ibleo (sicilia s.e.). s.el.ca., firenze. alessio m., allegri l., antonioli f., belluomini g., improta s., manfra l. & preite martinez m. (1994) – la curva di risalita del mare tirreno negli ultimi 43 ka ricavata da datazioni su speleotemi sommersi e dati archeologici. mem. descr. carta geol. d’it., 52, 261-276. antonioli f., borsato a., frisia s & silenzi s. (1998) l’uso degli speleotemi per ricostruzioni paleoclimatiche e variazioni del livello del mare . il quaternario, 11 (1), 67-78. carbone s., di geronimo i., grasso m., iozzis s. & lentini f. (1982) i terrazzi marini quaternari dell’area iblea (sicilia sud-orientale). c.n.r. – p.f.g. (sottoprogetto neotettonica), contributi conclusvi per la realizzazione della carta neotettonica d’italia, 506, 1-35. di grande a. & rraimondo w. (1982) linee di costa pliopleistoceniche e schema litostratigrafico del quaternario siracusano, geol. romana, 21, 279-309. bianca m. (1999) terrazzi marini e sollevamenti tettonici nel settore orientale del plateau ibleo. boll. acc. gioenia sci. nat., 31 (355), 51-60. bianca m., monaco c., tortorici l. & cernobori l. (1999) quaternary normal faulting in southeastern sicily: a seismic source for the 1693 large earthquake. geophys. j. int. 139, 370 -394. lambeck k., antonioli f., puecell a. & silenzi s. (2004) sea level change along the italian coast for the past 10,000 yrs. quat. sc. rev., 23, 1567-1598. leonardi r. (1994) contributo alla conoscenza delle grotte sommerse della penisola della maddalena (sr). boll. acc. gioenia sci. nat., 27 (348), 599-620. monaco c. & tortorici l. (2000) active faulting in the calabrian arc and eastern sicily . j. of geodynamics, 29, 407-424. monaco c., antonioli f., de guidi g., lambeck k., tortorici l. & verrubi v. (2004) tectonic uplift and sea-level change during the holocene in the catania plain (eastern sicily). quaternaria nova, 8, 171-185. ruggieri r. & amore c. (2000) elementi geostrutturali e paleomorfologici del sistema carsico grotta monello (sicilia sud-orientale). in: atti del i° seminario di studi sul carsismo negli iblei e nell’area sud-mediterranea. speleologia iblea, 8, 75-81. ruggieri r. & grasso m. (2000) caratteristiche stratigrafiche e strutturali dell’altipiano ibleo ragusano e sue implicazioni sulla morfogenesi carsica. in: atti del i° seminario di studi sul carsismo negli iblei e nell’area sud-mediterranea. speleologia iblea, 8, 19-35. waelbroeck c., labeyrie l., michel a., duplessy j.c., m c m a n u s j.f. l a m b e c k k., b a l b o n e. & labracherie m. (2002) sea-level and deep water temperature changes derived from benthic foraminifera isotopic records. quaternary sc. rev., 21, 295-305. 193 ms. ricevuto il 3 ottobre 2006 testo definitivo ricevuto il 5 dicembre 2006 ms. received: october 3, 2006 final text received: december 5, 2006 grotte carsiche e linee di costa sommerse ... dinamica recente ed attuale di alvei fluviali: alcuni casi di studio appenninici (italia centro-settentrionale) massimo rinaldi, liliana b.teruggi, cristina simoncini & laura nardi dipartimento di ingegneria civile e ambientale, università di firenze e-mail: mrinaldi@dicea.unifi.it riassunto: m. rinaldi et al., dinamica recente ed attuale di alvei fluviali: alcuni casi di studio appenninici (italia centro-settentrionale) (it issn 0394-3356, 2008). vengono analizzate e discusse le variazioni morfologiche recenti (ultimi 100 anni circa) e le tendenze attuali di tre casi di studio rappresentativi dell'appennino centro settentrionale: (1) fiume magra e suo principale affluente, fiume vara, relativi all'area appenninica compresa tra toscana settentrionale e liguria; (2) fiume panaro, rappresentativo del versante padano dell'appennino toscoemiliano; (3) fiume cecina, rappresentativo della toscana meridionale. tale studio è finalizzato principalmente ai seguenti obiettivi: (1) estendere le attuali conoscenze sull'evoluzione recente di alvei fluviali italiani a nuovi casi di studio dell'appennino centro-settentrionale; (2) confrontare tali casi tra loro per definirne gli aspetti evolutivi comuni e le differenze eventualmente da attribuirsi a particolari contesti geomorfologici e/o ad impatti antropici specifici. sono stati presi in esame i seguenti aspetti: (1) ricostruzione degli interventi antropici diretti ed indiretti per valutare il loro possibile ruolo nei confronti delle variazioni morfologiche degli alvei; (2) analisi delle variazioni morfologiche degli alvei: sono state acquisite ed analizzate tramite gis le cartografie e le foto aeree disponibili, in modo da permettere un confronto degli alvei in diversi anni e consentire la misura dei parametri planimetrici (larghezza dell'alveo, sinuosità, indice di intrecciamento), ed i rilievi topografici esistenti per ricostruire le variazioni di quota del fondo; (3) rilevamento geomorfologico di campo, attraverso l'applicazione di apposite schede focalizzate sull'interpretazione e la classificazione delle variazioni e delle tendenze attuali. i risultati possono essere sintetizzati come segue: (1) tutti i casi di studio sono stati interessati da abbassamento del fondo, con i casi di incisione più intensa (fino a valori di 7-10 m) registrati per il f. panaro e per il f. magra nel suo tratto inferiore; (2) analogamente, tutti i corsi d'acqua analizzati hanno subito un restringimento dell'alveo attivo; (3) si possono generalmente distinguere due fasi di aggiustamento morfologico (restringimento incisione), con la fase più intensa compresa tra gli anni '50 e i primi anni '90; (4) tali variazioni morfologiche sono fortemente correlate a fattori antropici, con rapporti causa effetto chiari e con modifiche di maggiore entità avvenute nei fiumi soggetti a maggiore impatto; (5) durante gli ultimi 10-15 anni circa, si osserva in alcuni casi una inversione di tendenza della larghezza (fase di allargamento, ad eccezione del f. cecina che continua nella sua fase di restringimento), accompagnata talora da situazioni di sedimentazione; (6) gli ultimi dati (2006/07) indicano in alcuni di questi casi una nuova lieve riduzione di larghezza. abstract: m.rinaldi et al., recent and present dynamics of river channels: some study cases from the apennines (central-northern italy. (it issn 0394-3356, 2008). during the last decades and centuries, many fluvial systems of the world have been heavily impacted by various types of human disturbances. regarding the italian rivers, a bibliographic review carried out by surian & rinaldi (2003) pointed out two main types of channel adjustments (incision and narrowing) and proposed a classification scheme of the types and amount of channel adjustments. from more recent studies (surian & rinaldi, 2004) it is emerging that an inversion of trend in width adjustments (widening) and/or in bed-level adjustments (aggradation) have recently occurred in some study cases. notwithstanding recent progress, there still remains the need to describe these processes more accurately and for a larger number of study cases. the research project prin 2005 "present and recent dynamics of river channels in northern and central italy: evolutionary trends, causes and management implications" has this general aim. this paper deals with changes and evolutionary trends of river channels in the northern apennines. the two main objectives of this research are: (1) to extend the knowledge of channel adjustments to new study cases in the northern apennine; (2) to compare such study cases to define common trends of adjustments and differences eventually related to different geomorphic contexts and human impacts. the following study cases have been selected, in order to represent different situations in the geographical context of central-northern apennines: (1) magra river and its main tributary, vara river; (2) panaro river; (3) cecina river, as a representative case of watershed located in southern tuscany. the following main aspects were investigated in detail: 1. reconstruction of human interventions and disturbances in order to verify their possible role on the channel adjustments. 2. analysis of channel changes. most of the available maps and aerial photos were acquired and analysed in gis, with the aim to allow for comparisons and measurements of the planimetric parameters (channel width, sinuosity, braiding index). then, a reconstruction of bed-level changes through the comparison of topographic surveys from different years was carried out. 3. field surveys. a series of forms for geomorphological field surveys were developed and applied to the study cases with a particular focus on the interpretation and classification of channel adjustments. the main results can be summarised as follows: (1) all study cases have been affected by channel bed incision, with the highest bedlevel lowering (up to 7-10 m) recorded along the panaro river and the lower part of the magra river; (2) similarly, all study cases have been affected by channel narrowing; (3) two phases of channel adjustment (incision narrowing) can be distinguished, with the phase of major changes occurring between about '50s and the beginning of '90s; (4) such changes appear strongly connected to human factors, with quite evident cause-effect relations, and with the highest changes occurring along the rivers with strong human impact; (5) during the last 10-15 years, an inversion of trend of channel width is observed (widening phase, except for the cecina river where the phase of channel narrowing is still continuing), coupled in some cases with situations of aggradation; however, during the last years (2006/07) a slightly new reduction in channel width is observed in some cases. parole chiave: variazioni morfologiche di alvei fluviali, fiumi italiani, impatti antropici keywords: channel adjustments, italian rivers, human impacts il quaternario italian journal of quaternary sciences 21(1b), 2008 291-302 292 m. rinaldi et al. 1. introduzione durante gli ultimi secoli, la maggior parte dei fiumi italiani è stata fortemente impattata da vari tipi di disturbi antropici e molti di questi corsi d'acqua stanno tuttora modificando, come risposta a tali impatti, la propria forma e le proprie dimensioni. tale dinamicità morfologica può determinare problemi in termini di rischi da dinamica d'alveo (danni a centri abitati, infrastrutture, perdita di terreni, possibili esondazioni connesse a processi di sedimentazione) ma, in molti casi, può avere effetti benefici per gli ecosistemi, promuovendo spontaneamente la diversificazione di habitat. pertanto la conoscenza delle tendenze evolutive dei corsi d'acqua è fondamentale sia ai fini della protezione e della sicurezza che in termini di gestione e riqualificazione fluviale. per quanto riguarda i fiumi italiani, esiste già una certa conoscenza delle variazioni morfologiche avvenute nel corso degli ultimi 100 150 anni. gli studi al riguardo partono da fine anni '70 inizi anni '80 (ad es. ca s t i g l i o n i & pe l l e g r i n i, 1981) e sono sempre più numerosi negli anni successivi (si veda ad es. braga & ge r v a s o n i, 1989; ca s t a l d i n i & pi a c e n t e, 1995; su r i a n, 1999; marchetti, 2002). surian & rinaldi (2003) hanno effettuato una rassegna di tutte le conoscenze acquisite sull'argomento, delineando i principali tipi di variazioni osservate in fiumi italiani e definendo uno schema generale di evoluzione. in alcuni casi (ad es. rinaldi & simon, 1998; rinaldi, 2003) è stata ben evidenziata l'esistenza di due principali fasi di aggiustamento morfologico: (a) da fine 1800 a metà del 1900, con incisioni e restringimenti meno intensi e legati soprattutto a fattori a scala di bacino; (b) seconda metà del 1900, con modifiche più forti legate soprattutto ad interventi ed attività in alveo. men o approfon dit e risu lt an o essere invece le conoscenze relative alle attu ali tenden ze evolutive dei corsi d'acqua italiani. da alcuni autori (su r i a n & ri n a l d i, 2 0 0 4 ; r i n a l d i et a l. , 2005a), limitatamente a qualche caso di studio, è stata osservata preliminarmente una inversione di tendenza delle larghezze e, in alc u ni c as i, d ell e qu o t e d el fondo. a seguito di questi studi, è maturata quindi la necessità di un approfondimento, descrivendo più accuratamente le variazioni passate ed attuali e per un numero più ampio di casi di studio, esigenze dalle quali è scatu rit o il pro get t o pri n 2 0 05 “dinamica recente ed attuale di alvei fluviali in italia centro-settentrionale: tendenze evolutive, cause ed implicazioni applicative”. in questo articolo si riportano sinteticamente i principali risultati relativi a tre casi di studio inclusi in questo progetto (r el at iv am en t e al l' u.o . di firenze), con i seguenti obiettivi: (1) estendere le attuali conoscenze sull'evoluzione recente di alvei fluviali italiani a nuovi casi di studio dell'appennino centro-settentrionale; (2) confrontare tali casi tra loro per definirne gli aspetti evolutivi comuni e le differenze eventualmente legate a contesti geomorfologici differenti e sia agli impatti antropici specifici. 2. casi di studio 2.1 inquadramento generale dei bacini i tre bacini di studio sono ubicati nell'italia centro settentrionale (fig. 1) e sono stati scelti in modo da essere sufficientemente rappresentativi di aree con condizioni morfologico climatiche relativamente diverse all'interno dell'appennino settentrionale. in tabella 1 sono riepilogate le principali caratteristiche morfologiche ed idrologiche dei tre bacini. il bacino del fiume magra è rappresentativo del versante appenninico ligure e della toscana settentrionale. esso ha una estensione di circa 1698.5 km2 ed è costituito da un sistema di due vallate tra loro parallele: ad occidente la valle del fiume vara, suo principale affluente (la cui area si estende per 572 km2), ad oriente l'alta media valle del fiume magra. le litologie affioranti nel sottobacino del vara sono a costituzione prevalentemente arenacea ed in subordine argillitico-marnosa, alle quali si aggiungono litologie calcaree ed in subordine metamorfiche magmatiche (versante nw delle alpi apuane) nel bacino del magra. il fiume panaro è scelto come rappresentativo del figura 1 bacini e tratti di studio. a: bacino del f. magra; b: bacino del f. panaro; c: bacino del f. cecina. 1: tratti di studio; 2: stazioni di misura idrometriche presenti lungo il f. magra e f. cecina. catchments and study reaches. a: magra r. catchment; b: panaro r. catchment; c: cecina r. catchment. 1: study reaches; 2: gauging stations along magra and cecina rivers. versante padano dell'appennino tosco-emiliano. il bacino ha una estensione di circa 1783 km2, simile quindi a quella del f.magra, con una forma spiccatamente allungata in direzione sw-ne. la fascia collinare e montuosa è interessata da litologie prevalentemente arenacee ed argilloso marnose, mentre la fascia di pianura è costituita da depositi recenti prevalentemente alluvionali. il fiume cecina è scelto come rappresentativo della toscana centro meridionale, e si diversifica dagli altri casi anche per le condizioni climatiche leggermente differenti, presentando caratteristiche più marcate di clima mediterraneo (temperato piovoso con estate asciutta e calda). il bacino ha una estensione di circa 905 km2, quindi è di dimensioni significativamente inferiori rispetto agli altri due casi; presenta un rilievo prevalentemente collinare, con rilievi meno accentuati rispetto alla catena appenninica. le porzioni più alte sono costituite da rocce prevalentemente calcareo argillitiche, mentre la fascia collinare ed il fondovalle sono impostati in litotipi prevalentemente di natura pelitica costituiti da depositi lacustri, marini e fluviali dei complessi neogenico quaternari. 293dinamica recente ed attuale di alvei ... 2.2 caratteristiche morfo-sedimentarie degli alvei fluviali sulla base di una prima osservazione delle foto aeree e di una ricognizione di campo iniziale, ognuno dei tre corsi d'acqua studiati è stato suddiviso in una serie di tratti con caratteristiche morfologiche relativamente omogenee, con particolare riferimento ai due seguenti aspetti: (a) morfologia del fondovalle (ampiezza, direzione della valle e grado di confinamento del fiume); (b) morfologia planimetrica dell'alveo. in particolare, sono stati in primo luogo distinti i principali tratti (ad es. ma, mb, …, me per il f.magra), in base prevalentemente alla morfologia del fondovalle, e successivamente ogni tratto è stato ulteriormente suddiviso in sottotratti (ad es. mb1, mb2, …, me1, me2) considerando con maggior dettaglio la forma planimetrica dell'alveo e le discontinuità idrologiche naturali in relazione alla presenza dei maggiori affluenti. l'analisi delle variazioni morfologiche, in particolare di quelle di larghezza, si è successivamente concentrata solo su alcuni di questi tratti o sottotratti (tab. 2) che presentassero le seguenti caratteristiche: (1) alvei alluvionali a fondo mobile senza significative costrizioni naturali da parte tabella 1 caratteristiche morfologiche ed idrologiche generali dei bacini di studio. a: area del bacino (in parentesi l'area sottesa dalla stazione di misura delle portate); l: lunghezza del fiume; δh: dislivello del bacino; p: precipitazioni medie annue; qmed: portata giornaliera media annua; qmax: portata massima. general morphological and hydrological characteristics of the study basins. a: drainage basin area (in parentheses the drainage basin areas upstream of the gauging stations to which the discharges are referred); l: river length; δh: basin relief; p: mean annual rainfall; qmed: mean annual daily discharge; qmax: maximum peak discharge. fiume a (km2) l (km) δh (m) p (mm) qmed (m 3/s) qmax (m 3/s) magra 1698.5 (932) 69.5 1639 1707 40.8 1440 vara 572 (205) 65 1603 1770 8.3 518 panaro 1783 (1036) 165 2157 1017 19 1400 cecina 905 (634) 53 1018 944 7.6 1030 tabella 2 caratteristiche morfologico sedimentarie generali dei tratti di studio. general morphological sedimentary characteristics of the study reaches. fiume lunghezza morfologia alveo pendenza fondo d50 sedimenti tipi di sponde tratto di studio (%) fondo (mm) (km) magra superiore 10 transizionale 0.86 0.95 45.3 90.9 principalmente non coesive (mb) (wandering) media: 0.9 media: 62.3 (ghiaia grossolana) magra inferiore 11 transizionale 0.15 0.42 20.9 39.7 principalmente composite (md2-me1) (wandering) media: 0.24 media: 29.4 (ghiaia basale, livello coesivo superiore) vara medio22 sinuoso (vc2-vd) 0.28 0.47 12.4 52.3 da non coesive (ghiaia inferiore transizionale media: 0.37 media: 38.4 grossolana) (vc2-vd) a (vc2-vd, ve) (wandering) (ve) composite (ghiaia basale, livello coesivo superiore) (ve) panaro medio 38 da transizionale 0.05 0.4 27.1 90.0 da composite (ghiaia basale, (pa, pb, pc) (pa) a sinuosomedia: 0.2 media: 49.0 livello coesivo superiore) meandriforme (pc) a coesive cecina medio40 transizionale 0.21 0.5 11.6 34.4 da non coesive (ghiaia) a inferiore (wandering media: 0.3 media: 18.1 composite (ghiaia basale, (cb, cc, cd1) sinuoso con barre livello coesivo superiore) alternate) dei versanti (alvei non confinati); (2) sono stati evitati tratti eccessivamente controllati da opere idrauliche (in particolare i tratti finali di tutti e tre i casi di studio: pd, me2, cd2) per i quali le variazioni planimetriche fossero state condizionate o completamente impedite dalla presenza di sponde fisse. e' s ta t a eff et t u at a u n a campagna di misura delle granulometrie dell'alveo, ai fini di una caratterizzazione generale delle dimensioni granulometriche e delle loro variazioni spaziali. le misure sono state condotte attraverso il metodo di campionamento statistico (p e bble counts) (wolman, 1954; bunte & abt, 2001), con stendimenti effettuati sulle superfici di b arr e at t i v e emer s e. ta li misure hanno riguardato l'intera lunghezza dei fiumi magra, vara e cecina (per lunghezze dell'ordine dei 40-50 km), mentre per il f.panaro i rilievi granulometrici sono stati limitati ai tratti pa e pb (lunghezza di circa 20 km). il principale risultato di tali misure, in termini di variazioni spaziali del diametro mediano dei sedimenti (d50), è riportato in figura 2: si osservano delle oscillazioni relativamente forti, rispetto al trend discendente verso valle, riconducibili principalmente agli apporti laterali e, nel caso del panaro, alla presenza di numerose opere trasversali. il range di variabilità generale è compreso tra i 10 e 90 mm circa, con i sedimenti relativamente più fini presenti lungo il f.cecina (d50 compresi tra 13.7 e 45.3 mm). un riepilogo delle caratteristiche morfologiche e sedimentarie complessive dei tratti di studio è riportato in tabella 2. e' possibile notare come i tratti di studio presentino caratteristiche simili in termini di morfologie, con prevalenza di tipologie transizionali (wandering o sinuoso a barre alternate), eccetto per il tratto inferiore del panaro (pc), caratterizzato da una morfologia a canale singolo sinuoso-meandriforme. le pendenze del fondo sono piuttosto variabili, con valori dell'ordine di 0.004 0.009 nei tratti medio alti (mb, pa, cb) a valori dell'ordine di 0.0005 0.002 nei tratti inferiori (me, pc, cd). 2.3 impatti antropici in tabella 3 si riporta un quadro riepilogativo dei 294 figura 2 andamento spaziale del diametro mediano dei sedimenti lungo i fiumi studiati. spatial trend of median diameter of bed sediments along the study rivers. tabella 3 riepilogo dei principali tipi di impatti antropici e relative epoche per i casi di studio. summary of the main human impacts and relative periods for the study cases. fiume dighe e area del opere trasversali periodo di costruzione di rimboschimenti sistemazioni bacino a monte (soglie, briglie, intensa argini e di nel bacino idraulico(%) traverse) nei tratti escavazione protezioni forestali nel di studio di sedimenti di sponda bacino magra 3 piccole dighe alcune traverse nel anni '60 '70 dagli anni '20 primi decenni primi decenni lungo affluenti tratto inferiore realizzazione di del xx secolo del xx secolo (metà del xx (seconda metà pennelli lungo i secolo) per energia xx secolo) tratti inferiori idroelettrica: area (md2-me1) a monte circa 4 % vara 1 diga nel tratto soglie nel tratto anni '60 '70 dagli anni '20 primi decenni primi decenni medio (anni '30): inferiore (ve) realizzazione di del xx secolo del xx secolo area a monte 43 % (anni '80) pennelli lungo il tratto inferiore (ve) panaro 1 piccola diga numerose briglie nel anni '60 '90 anni '20 '60 primi decenni primi decenni lungo affluente tratto medio (pa, pb) del xx secolo del xx secolo, (metà del xx (principalmente anni continuati fino a secolo): area a '70 '80) e opera fine anni '80 monte circa 3 % derivazione cassa di espansione (pc) (anni '80) cecina alcune traverse nel anni '70 argini e pennelli primi decenni primi decenni tratto medio inferiore discontinui durante del xx secolo del xx secolo (xix e xx secolo) i primi decenni del xx secolo lungo il tratto medioinferiore (cc, cd) m. rinaldi et al. principali tipi di interventi e disturbi antropici che hanno potuto avere influenza sulla dinamica fluviale dei corsi d'acqua studiati nel periodo di indagine. tutti i casi di studio sono stati interessati in linea di massima dagli stessi tipi di impatti, ad eccezione delle dighe e delle opere trasversali lungo i tratti di studio, assenti solo nel caso del f. cecina l'impatto più forte è stato senza dubbio l'intensa escavazione di sedimenti soprattutto lungo il f. panaro, in tutto il tratto di studio, e lungo i tratti inferiori del f. vara e soprattutto del f. magra, a valle della loro confluenza. alcuni dati possono risultare utili per meglio comprendere l'impatto rilevante prodotto da tale attività. per quanto riguarda i fiumi magra e vara, è stato stimato che i quantitativi estratti complessivamente nei loro tratti vallivi tra 1958 e 1973 si aggiri attorno a 24.400.000 m3 (cavazza & pregliasco, 1981), a fronte di un trasporto solido al fondo medio annuo, per il tratto inferiore del f. magra, che è stato stimato essere dell'ordine di 30.000 36.000 m3/anno (cavazza & preglias c o, 1981; ri n a l d i, 2007). nel caso del f. panaro, il periodo di massima intensità delle escavazioni è stato tra il 1960 ed il 1980, con quantitativi estratti, secondo i dati ufficiali, di circa 5.900.000 m3 tra 1962 e 1980, e con il picco annuo raggiunto nel 1973 con 720.000 m3 circa. non esistono stime sul trasporto solido di questo corso d'acqua, ma certamente il rapporto tra tassi di escavazione e di trasporto al fondo, dal quale dipende molto il tipo e l'intensità della risposta morfologica dell'alveo (ri n a l d i et al., 2005b), sono anche in questo caso molto elevati. per quanto riguarda il f. cecina, non esistono dati o informazioni precise relative a questa attività. si può certamente affermare che tale fiume è stato meno interessato dall'escavazione di sedimenti, rispetto ai casi precedenti, e che questa attività si è comunque concentrata durante i primi anni '70, in concomitanza con la realizzazione di varie infrastrutture e vie di comunicazione nelle aree limitrofe. 3. dati raccolti e metodi un riepilogo di tutti i dati e materiali utilizzati è riportato in tabella 4. i metodi impiegati consistono in: (a) confronto di cartografie storiche e foto aeree; (b) confronto dei rilievi topografici; (c) rilevamenti geomorfologici di campo. le foto aeree sono state elaborate attraverso il software arcgis (arcinfo), il quale ha permesso di rettificare e georeferenziare le immagini in modo da poterle sovrapporre tra loro ed effettuare le misure dei parametri di interesse. per ogni anno disponibile, è stato tracciato l'asse dell'alveo attivo e sono state definite sezioni ad esso ortogonali con passo variabile a seconda dei casi di studio. per quanto riguarda i fiumi vara e magra, si sono in parte utilizzate misure già effettuate in studi precedenti (ri n a l d i et al., 2005a; ri n a l d i, 2005) per i quali sono state impiegate le sezioni topografiche del 1989, aventi un passo di 200 250 m circa, pari a circa da 1 a 2 volte la larghezza dell'alveo attuale. per il f. panaro ed il f. cecina si è preferito effettuare le misure con un passo rispettivamente di 50 m e 40 m, cioè pari a circa da 0.5 a 1 volta la larghezza attuale. e' stata misurata sia la larghezza totale, comprensiva cioè di eventuali isole vegetate, che la larghezza dell'alveo attivo, escluse le isole. per tutti i casi di studio sono state utilizzate anche carte storiche le quali, seppure con un margine di errore superiore rispetto alle foto aeree, sono state ritenute sufficientemente attendibili, nonché fondamentali per la comprensione dei trend di larghezza di più lungo termine e soprattutto per ricavare una stima della larghezza iniziale del periodo investigato. per quanto riguarda i dati altimetrici, la ricostruzione delle variazioni di quota del fondo è stata effettuata limitatamente ad alcuni tratti dei fiumi magra e vara per i quali erano disponibili rilievi topografici relativi ad anni diversi. per quanto riguarda i rilievi geomorfologici di campo, sono state utilizzate le schede di rilevamento descritte da rinaldi (2008) o, per i fiumi magra e vara, versioni precedenti delle stesse (ri n a l d i, 2005). tali schede hanno permesso, oltre alla descrizione delle caratteristiche morfologiche generali, anche di classificare le variazioni altimetriche di periodi precedenti, in base a differenze di quota tra superfici omologhe, e di 295 tabella 4 riepilogo dei dati utilizzati. summary of data used. dati f. magra f. vara f. panaro f. cecina cartografie storiche (scala) 1823 (1:50.000), 1852 1890 (1:25.000 1:50.000) 1883 (1:50.000) (1:50.000), 1877 (1:50.000), 1908 (1:25.000) foto aeree o cartografie 1937/38 (1:18.000), 1954 1934/35 (1:25.000) 1954 (1:33.000) (scala) (1:66.000), 1971 (1:66.000), 1954/55 (1:33.000) cd1: 1976 (1:15.000) 1981 (1:66.000), 1992 1962/69 (1:5.000) 1986 (1:15.000) (1:66.000), 1995 (1:40.000), 1981 (1:33.000) 1994 (1:33.000) 1999 (1:40.000) 1997 (1:15.000) 1999 (1:40.000) 2003/04 (1:33.000) 2000 (1:40.000) 2004 (1:7.500) mb, md, me: 2006 (1:8.000) pb: 2007 (1:7.000) rilievi topografici mb: 1989, 2006 1991 2004 md-me: 1914, 1958, 1971, 1989, 1999/200, 2006 vd-ve: 1958, 1971, 1989, 1999/2000 rilievi geomorfologici e 2003/06 2006/07 2005/07 sedimentologici dinamica recente ed attuale di alvei ... valutare le tendenze attuali, in base ad una serie di variabili appositamente definite (quali differenze altimetriche tra superfici, caratteristiche delle barre, corazzamento e caratteristiche tessiturali dei sedimenti, evidenze vegetazionali, ecc.). 4. variazioni morfologiche 4.1 variazioni planimetriche i trend temporali di variazioni di larghezza sono riportati in figura 3a, dove si confrontano tra loro i dati relativi a tutti i sottotratti dei casi di studio analizzati. la prima osservazione di carattere generale che si può effettuare è la progressiva riduzione di larghezza nel tempo, almeno fino alla fine degli anni '9 0 ci rca : per i s ol i cas i del basso magra (md2 ed me1), si nota nel 1954 un temporaneo incremento di larghezza rispetto al dato precedente (1938). dalla fine degli anni '90 in poi si nota qualche caso di inversione di tendenza con un lieve incremento di larghezza, o comunque una situazione di maggiore equilibrio. al fine di rendere meglio confrontabili tra loro i risultati, in un secondo grafico la larghezza è s t at a ad ime n si o n ali zzat a rispetto al valore massimo registrato nel periodo (fig. 3b) (quest'ultimo associato sempre al primo valore di larghezza misurato sulle carte storiche). da tale grafico è possibile più agevolmen t e id en t if ica re l e fas i di aggiustamento generalizzabili o meno a tutti i casi di studio. infine, nella figura 3c si riportano i tassi medi di variazione per ognuna delle fasi di evoluzione, ed in tabella 5 si riporta un riepilogo delle caratteristiche principali delle varie fasi. si riepilogano di seguito le caratteristiche generali delle varie fasi: (1) prima fase di restringiment o (fase 1): caratterizzata da un restringimento molto significativo, verificatosi nella maggior parte dei casi tra fine 1800 inizi 1900 e anni '50 inizi anni '70; (2) seconda fase di restringimento (fase 2): caratterizzata da un restringimento alt rettan to 296 figura 3 variazioni di larghezza. a: trend temporali delle larghezze. b: andamento delle larghezze (l) adimensionalizzate rispetto alla larghezza massima (lmax) del periodo di misure. c: tassi di variazione medi (δl/t) per le varie fasi di aggiustamento morfologico. i simboli rappresentano il tasso di variazione attribuito al punto medio dell'intervallo di tempo, quest'ultimo rappresentato dalla linea. changes in channel width. a: temporal trends of channel width changes. b: trend of channel widths (l) nondimensionalised by the maximum width of the period (lmax). c: mean rates of width change (δl/t) for each of the phases of channel adjustments. symbols represent the rates associated to the mean point of the time intervals, the latter represented by the lines. m. rinaldi et al. significativo ma, essendosi manifestato in un intervallo di tempo inferiore, con tassi di variazione in genere più elevati. nella maggior parte dei casi la fase 2 si è manifestata dalla fine della precedente a fine anni '90; (3) fase di allargamento (fase 3): non è sempre presente, in quanto alcuni tratti sono tuttora in restringimento. quando presente, è iniziata a fine anni '90 ed è caratterizzata da un aumento di larghezza, con tassi in alcuni casi anche molto significativi, oppure da un aumento seguito poi da una nuova riduzione (ma il cui valore finale è comunque maggiore rispetto al minimo raggiunto alla fine della fase 2). rispetto a tale modello generale, si rimarcano di seguito alcuni dei principali discostamenti: (1) per il f. panaro nel tratto pb, la fase 2 di restringimento è ancora in atto, dopo una lieve inversione di tendenza tra 1997 e 2000. per i tratti pa e pc non è stato possibile verificare se esistesse tale restringimento in quanto non era disponibile il volo aereo 2007, per questo motivo l'esistenza di una effettiva fase 3 di riallargamento è incerta. (2) il f. cecina rappresenta un caso che si discosta ulteriormente dagli altri, in quanto: (a) la fase 1 si prolunga fino a fine anni '80 inizi anni '90; (b) analogamente al tratto pb, la fase 2 di restringimento è ancora in atto in tutti e tre i tratti di studio (cb, cc e cd1). in sintesi, sembra che le fasi evolutive lungo il f. cecina si siano verificate e si stiano tuttora verificando con un certo sfasamento (ritardo) rispetto al modello generale. 4.1 variazioni altimetriche in tabella 6 si riporta un riepilogo delle variazioni di quota del fondo rispetto a fine 1800, stimate sulla base dei rilievi topografici disponibili (f. magra e f. vara) o valutate in base ad osservazioni di campo. si osserva come i valori più alti di abbassamento si registrano lungo il tratto inferiore del f. magra e lungo tutti i tratti di studio del f. panaro, laddove è stata più forte l'attività di escavazione di sedimenti durante i decenni passati. i valori più contenuti di abbassamento sono invece osservati lungo i tratti medi del f. vara e del f. cecina. per quanto riguarda le tendenze attuali, eccetto per il f. magra per il quale erano disponibili rilievi topografici eseguiti negli ultimi 10 anni, in tutti gli altri casi le valutazioni si sono basate esclusivamente su osservazioni di campo, le quali non sono in grado di fornire delle stime ma solo di classificare la tendenza prevalente. in generale si sono osservate prevalentemente situa297 fiume tratto variazioni stimate rispetto a fine 1800 tendenze attuali (ultimi 10 anni circa) magra mb 2 4 m equilibrio / sedimentazione md2-me1 5 8 m equilibrio / sedimentazione vara vc2-vd 1 3 m equilibrio / sedimentazione ve 2 4 m equilibrio / sedimentazione panaro pa 4 6 m equilibrio pb 6 10 m equilibrio pc 4 6 m equilibrio cecina cb 1 2 m equilibrio (sedimentazione) cc-cd1 2 3 m equilibrio (sedimentazione) tabella 5 riepilogo delle variazioni di larghezza suddivise per fasi evolutive. t1, t2 e t3: intervalli di tempo relativi alle fasi 1, 2 e 3 rispettivamente; δl: variazione di larghezza; δl/(lmax-lmin): rapporto tra variazione di larghezza in una fase evolutiva e differenza tra larghezza massima e minima dell'intero periodo. summary of channel width changes for each phase of evolution.t1, t2, t3: time intervals of the phases 1, 2, and 3 respectively; δl: width change; δl/(lmax-lmin): ratio between width change of a phase of evolution and difference between maximum and minimum width of the entire period. tratto fase 1 fase 2 fase 3 t1 δl δl/(lmaxt2 δl δl/(lmaxt3 δl (m) δl/(lmax(m) lmin) (%) (m) lmin) (%) lmin) (%) mb 1877-1954 -105.9 -47 1954-1995 -120.3 -53 1995-2006 37.1 16 md2 1877-1954 -246.9 -47 1954-1995 -279.5 -53 1995-2006 15.5 3 me1 1877-1954 -268.5 -42 1954-2003 -375.3 -58 2003-2006 10.6 2 vc2-vd 1877-1971 -118.2 -62 1971-1995 -70.9 -38 1995-2004 13.3 7 ve 1877-1954 -301.0 -68 1954-1995 -140.2 -32 1995-2004 9.4 2 pa 1890-1969 -84.1 -47 1969-1997 -94.9 -53 1997-2000 0.8 0.4 pb 1890-1969 -118.3 -41 1969-2007 -167.7 -59 pc 1890-1969 -137.4 -69 1969-1997 -60.5 -31 1997-2000 5.9 3 cb 1883-1986 -68.9 -50 1986-2004 -69.4 -50 cc 1883-1994 -76.6 -81 1994-2004 -18.2 -19 cd1 1883-1994 -116.6 -89 1994-2004 -13.6 -10 tabella 6 riepilogo delle variazioni di quota del fondo (da dati topografici disponibili e rilievi di campo). summary of bed-level changes (from available topographic data and field surveys). dinamica recente ed attuale di alvei ... zioni di equilibrio e/o sedimentazione, quest'ultima spesso localizzata in alcuni punti o sottotratti piuttosto che generalizzata. per quanto riguarda il f. panaro non sono state osservate evidenze generalizzate di sedimentazione o di incisione, pertanto la situazione dominante è stata classificata come di equilibrio. tale situazione di equilibrio del fondo è tuttavia fortemente condizionata dalla presenza di numerose traverse lungo il tratto di studio, in assenza delle quali è possibile che il fondo sarebbe ancora in fase di incisione. anche nel caso del f. cecina la situazione più frequente è stata quella di equilibrio, seppure spesso sono state osservate evidenze di situazioni di sedimentazione piuttosto localizzata in alcuni punti. le informazioni disponibili sull'evoluzione temporale della quota del fondo sono limitate solo ai tratti inferiori dei fiumi magra e vara, per i quali si dispone di un numero relativamente elevato di profili del fondo. a titolo di esempio si riporta in figura 4 il trend evolutivo della quota del fondo (media del tratto) relativa ai due tratti md2 ed me1 del f. magra: è possibile osservare in entrambi i casi un andamento piuttosto simile di abbassamento del fondo tra 1914 e 1989, con un incremento del tasso di abbassamento successivo al 1958 (più evidente nel sottotratto me1). per quanto riguarda gli anni successivi al 1989, si osserva in entrambi i casi una inversione di tendenza, ancora in atto nel sottotratto md2, mentre nel sottotratto me1 l'ultimo rilievo (2006) registra una nuova flessione della quota del fondo. risulta particolarmente interessante riportare sugli stessi grafici l'andamento temporale della larghezza dell'alveo, in modo da poter verificare l'esistenza di interazioni tra i due tipi di aggiustamento morfologico. per quanto riguarda le modifiche precedenti al 1989, si nota come restringimento ed abbassamento procedono in maniera analoga, eccezione fatta per l'incremento di larghezza nel 1954 già osservato precedentemente. successivamente al 1989, è ancora più interessante osservare come ci sia una buona corrispondenza tra inversioni di tendenza del fondo e di larghezza: ad un aumento di larghezza corrisponde un innalzamento della quota del fondo e viceversa, ed è anche interessante notare che le variazioni di quota sono molto più significative, se rapportate alla variazione totale del periodo, rispetto alle variazioni di larghezza. 5. sintesi e discussione dei risultati i risultati di questa ricerca permettono di avere a disposizione un numero più ampio di casi di studio per i quali sono ben definiti i trend di aggiustamento morfologico, rispetto a quanto già noto sull'evoluzione di alvei fluviali dell'appennino settentrionale (ri n a l d i, 2003; rinaldi et al., 2005a). in figura 5 si riporta schematicamente l'evoluzione dei casi di studio analizzati. tale modello di evoluzione ripercorre quello già proposto da surian & rinaldi (2004), il quale si riferiva a cinque tratti di fiumi dell'italia settentrionale (tra i quali il tratto del f. vara qui indicato come ve) a morfologia inizialmente a canali intrecciati. tuttavia il modello proposto è più articolato, volendo evidenziare alcune differenze osservate tra i vari casi di questo studio. in generale, si distinguono quattro stadi di evoluzione, descritti sinteticamente come segue: (1) stadio i: morfologia iniziale di fine 1800 inizi 1900, a canali intrecciati o wandering; (2) stadio ii: alveo parzialmente inciso e ristretto del periodo 1950 1970 circa, a seguito della prima fase di aggiustamento; (3) stadio iii: alveo con incisione e restringimento massimi di fine anni '90 o ancora in atto, a seguito della fase 2 di variazioni più intense; (4) stadio iv: alveo con inizio di inversione di tendenza e parziale recupero morfologico. l'evoluzione dei fiumi magra e vara coincide esattamente con quanto già rappresentato nel modello di su r i a n & ri n a l d i (2003), mentre i f. panaro e f. cecina denotano alcune differenze. il f. panaro subisce una incisione mediamente più forte rispetto ai casi precedenti (in particolare nel tratto pb), presenta nello stadio iii una morfologia solo in alcuni tratti a barre alternate, mentre in altri casi raggiunge una configurazione a canale singolo quasi priva di barre. lo stadio iv di parziale recupero morfologico è possibile per i tratti pa e pc, mentre il tratto pb è tuttora nello stadio iii. nel caso del f. cecina, la morfologia iniziale è meglio descritta come w a n d e r i n g (seppure in periodi ancora precedenti era probabilmente a canali intrecciati e continua ad esserlo localmente nello stadio i) ed evolve verso una configurazione a barre alternate e, soprattutto nel tratto cc, l'ulteriore riduzione di larghezza e l'aumento di sinuosità stanno determinando una possibile evoluzione verso una morfologia meandriforme (con 298 figura 4 trend t em po r al i de lle quote del fondo e delle larghezze dell'alveo lungo il t r at to inf er io r e del f.magra. a: t r at to m d2 ; b : tratto me1. temporal trends o f be d -l ev e l c han g es a lo ng the lower magra. a: md2 reach; b: me1 reach. m. rinaldi et al. barre di meandro). l'indice di sinuosità risulta infatti significativamente aumentato tra il 1986 ed il 2004, soprattutto nel tratto cc, mentre il tratto cb è quello in cui si è avuto un maggiore restringimento accompagnato ad una trasformazione morfologica da w a n d e r i n g (localmente a canali intrecciati) a canale sinuoso a barre alternate. la figura 5b mette schematicamente in evidenza una caratteristica comune ai vari casi di studio. si possono considerare nell'ordine le seguenti quattro morfologie, in senso decrescente di larghezza: (a) canali intrecciati; (b) wandering; (c) sinuoso a barre alternate; (d) meandriforme a barre di meandro. quello che si è osservato è un passaggio di morfologie seguendo una traiettoria comune (da a verso d), con la morfologia finale che è funzione di quella iniziale e dell'entità delle variaz io n i. a d es emp io , i fi u mi magra, vara e panaro partono tutti da una morfologia a canali intrecciati ma il panaro subisce u n g ra do di t r as fo rm azio n e maggiore, mentre il f. cecina parte da una morfologia wandering e si avvicina ad una morfologia meandriforme. nel caso in cui esiste una fase di parziale recupero morfologico (ad esempio per f. magra e f. vara), la tendenza è quella di ripercorrere la stessa traiettoria in sen so contrario. e' opportuno a questo punto porre la questione di quali siano le cause di tali variazioni, ed in particolare quali siano le variabili (ad es. portate liquide e/o solide) dalle cui modifiche dipendan o t ali ten den ze pas s ate ed attuali. l'associazione causa effetto tra variazioni morfologiche osservate ed impatti antropici è evidente (tab. 3 e fig. 6). come già osservato precedentemente (si veda ad es. rinaldi, 2003; surian & rinaldi, 2003), la f as e 1 d i ab bas s ame n t o e restringimento è associabile a con dizionamen ti prev alent emente a scala di bacino, mentre la fase 2 è associabile soprattutto al periodo di intensa escavazione di sedimenti dagli alvei. più difficile è identificare possibili fattori naturali che possano a v ere co n t ri bu i t o alm en o in parte a tali modifiche. se si considerano ad esempio le variazioni climatiche, l'unico parametro che può essere realmente preso in considerazione è la precipitazione, in quanto le portate liquide sono a loro volta influenzate da fattori antropici. per quanto riguarda il bacino del f. magra, sono state analizzate numerose serie storiche di precipitazioni totali annue relative a diverse stazioni pluviometriche (rinaldi, 2005), e da tale analisi non si denotano tendenze significative, osservandosi solo una riduzione molto modesta delle precipitazioni nel tempo. analoghe osservazioni sono state fatte per il bacino del f. arno (billi & rinaldi, 1997; agnelli et al., 1998). non è ancora possibile invece fare considerazioni sulle possibili variazioni climatiche in atto e sul loro eventuale ruolo nei confronti della fase di recupero morfologico. informazioni ancora più limitate sono quelle relative ad una possibile influenza della tettonica attiva, ma sulla base della letteratura esistente (surian & rinaldi, 2003) esiste un sostanziale accordo nel ritenere che tale fattore possa influire solo in piccola parte, ma certamente 299 figura 5 riepilogo delle variazioni morfologiche. a: modello evolutivo dei tre casi di studio. b: variazioni della morfologia d'alveo. le frecce rivolte verso il basso indicano le variazioni di pattern durante le fasi di incisione e restringimento (fasi 1 e 2); la freccia rivolta verso l'alto indica la fase 3 di parziale recupero morfologico (solo per f. magra f. vara). morfologie d'alveo: (a) a canali intrecciati; (b) wandering; (c) sinuoso a barre alternate; (d) meandriforme a barre di meandro. summary of morphological change. a: model of channel evolution for the three study cases. b: changes in channel morphology. the arrows turned down point out the changes in channel pattern during the phases of incision and narrowing (phases 1 and 2); arrow turned up point out the phase 3 of partial morphological recovery (only for magra r. vara r.). channel morphologies: (a) braided; (b) wandering; (c) sinuous with alternate bars; (d) meandering with point bars. dinamica recente ed attuale di alvei ... no n p u ò s pieg are v ar iazi on i morfologiche così significative come quelle osservate negli ultimi 100 anni circa. i fattori antropici hanno potuto determinare le variazioni morfologiche osservate in vari modi: (a) modificando direttamente l'alveo (ad esempio tramite pennelli, canalizzazioni ed in parte escavazione di sedimenti); (b) modificando le variabili guida (portate liquide e solide) le cui variazioni possono avere in dot to ag giu st ament i morfologici dell'alveo. per quanto riguarda il secondo caso, si può osservare che, nei casi di studio in esame, la gran parte degli impatti antropici ha avuto un effetto prevalentemente sulle portate solide, piuttosto che su quelle liquide. le dighe possono avere avuto una certa influenza riducendo anche le portate di piena (oltre che le portate solide), ma tale effetto potrebbe essere stato significativo solo per il f. vara (negli altri casi i bacini sottesi da digh e sono poco significativi), mentre tutti gli alt ri t ipi di int erven ti non han no significat ive influ en ze sulle portate di picco. per le uniche due stazioni di misura (f. cecina e f. magra) che hanno registrato con continuità le portate massime annuali, è stato verificato che non esistono anomalie particolari nell'andamento delle portate nell'intervallo in cui si sono verificate le maggiori variazioni morfologiche (rinaldi, 2005). analoghe osservazioni erano state fatte per il f. arno (ri n a l d i, 2003), per il quale non è osservabile alcuna evidenza di variazioni significative nell'intensità e frequenza di eventi di piena in grado di spiegare l'accelerazione della fase di incisione nella seconda metà del xx secolo. e' pertanto evidente che la variabile guida principale dalle cui variazioni sono dipesi gli aggiustamenti morfologici è rappresentata dalle portate solide. le variazioni di portate solide possono essere principalmente avvenute: (1) a scala di bacino, attraverso variazioni di uso del suolo (rimboschimenti) e realizzazione di briglie; (2) riduzione della quantità di sedimenti disponibili in alveo per il trasporto solido al fondo, a causa dell'asportazione diretta di sedimenti dagli alvei. la relazione tra variazioni di portate solide e di larghezza dell'alveo è consistente con quanto riportato in letteratura: in particolare, il modello di aggiustamenti morfologici proposto da sc h u m m (1977) prevede, seppure solo in termini qualitativi, una riduzione della larghezza in conseguenza di una riduzione delle portate solide e viceversa. la riduzione di portate solide può non essere l'unico fattore che ha determinato le fasi di restringimento: un certo ruolo può essere stato giocato anche dalla realizzazione di pennelli ed altre difese di sponda. questo è particolarmente evidente per il basso magra e basso vara, dove negli anni '30 sono stati realizzati numerosi pennelli. d'altra parte tali interventi non possono essere considerati l’unica causa di restringimento, in quanto la riduzione di larghezza si è registrata anche in numerosi altri casi dove non si sono realizzati pennelli. un approfondimento particolare della discussione va dedicato infine alla eventuale esistenza di una fase di recupero morfologico iniziata negli ultimi anni. e' necessario innanzitutto notare che tale fase, alla luce dei casi di studio qui esaminati, appare meno chiara e meno diffusa di quanto non sembrasse in precedenti studi (su r i a n & ri n a l d i, 2004; ri n a l d i et al., 2005a). i quesiti fondamentali che si pongono sono: (1) quali sono le cause dell'inversione di tendenza, laddove si è verificata; (2) perché non si è verificata in tutti i casi. nell'ambito dei casi di studio analizzati, una inversione di tendenza della larghezza si è verificata con chiarezza nei f. magra e f. vara, seppure ad una fase di riallargamento piuttosto marcato iniziata generalmente intorno al 1995 è quasi sempre seguita una nuova riduzione di 300 figura 6 schema riepilogativo delle variazioni morfologiche complessive (rispetto alla situazione iniziale di fine 1800) in funzione della morfologia iniziale e del grado relativo di impatto antropico. classi di incisione: im) moderata (tra 1 e 2 m); ii) intensa (tra 2 e 4 m); iii) molto intensa (>4 m). classi di restringimento: rm) moderato (tra 20 e 50%); ri) intenso (tra 50 e 70%); rii) molto intenso (>70 %). summary sketch of the overall morphological changes (compared to the initial situation at the end of 1800) as a function of the initial morphology and the relative degree of human impact. classes of incision: im) moderate (between 1 and 2 m); ii) intense (between 2 and 4 m); iii) very intense (>4 m). classes of narrowing: rm) moderate (between 20 and 50%); ri) intense (between 50 and 70%); rii) very intense (>70 %). m. rinaldi et al. larghezza negli ultimi anni. la figura 4 mostra chiaramente come tali oscillazioni di larghezza siano strettamente legate anche a variazioni della quota del fondo. un contributo a tali tendenze recenti può essere certamente legato a due eventi di piena di forte intensità verificatisi nel 1999 e nel 2000, i quali hanno certamente causato la riattivazione di numerosi processi erosivi e di produzione di sedimenti a scala di bacino. va tuttavia notato che l'inversione di tendenza non può essere attribuita esclusivamente a tali piene, in quanto essa era già iniziata tra il 1995 ed il 1999. e' presumibile quindi che tali primi segnali di allargamento siano legati ad un inizio di riattivazione di processi erosivi, avvenuto anche durante piene di non eccezionale intensità verificatesi in quegli anni, che ha fatto seguito, con un certo ritardo, al termine della fase di intensa attività di escavazione di sedimenti. a ciò si aggiunge il fatto che, durante questi ultimi anni, le rimozioni di sedimenti e le protezioni di sponda sono state molto ridotte e limitate a situazioni localizzate. piuttosto inaspettata appare la riduzione di larghezza manifestatasi in gran parte dei casi (seppure talora molto limitata) durante gli ultimi anni. da una attenta analisi da foto aeree delle situazioni in cui tale riduzione si è manifestata, essa appare sostanzialmente legata ad una parziale ricolonizzazione da parte di vegetazione di superfici relativamente meno attive che si erano probabilmente rimodellate durante gli eventi del 1999-2000, a causa dell'assenza di eventi di piena successivi altrettanto intensi. pertanto, si può concludere che per i fiumi magra e vara non si può parlare di una fase attuale univoca di riallargamento, ma piuttosto di una fase di oscillazioni morfologiche nella direzione di un parziale recupero (inversione di tendenza rispetto alla fase precedente), guidate dal verificarsi di eventi di piena di una certa intensità e dall'intervallo di tempo intercorrente tra eventi successivi. per quanto riguarda il f. panaro, per due tratti si è verificata una lieve inversione di tendenza (tra 1997 e 2000) mentre nel caso del tratto pb, per il quale si disponeva anche del volo più recente del 2007, la tendenza risulta essere tuttora in restringimento. l'assenza di una chiara fase di recupero morfologico può essere legata ai seguenti fattori: (1) sostanziale deficit di sedimenti in alveo (si ricorda che in alcuni tratti il corso d'acqua ha eroso tutto il materasso alluvionale andando ad incidere il substrato); (2) discontinuità longitudinali (numerose briglie) che ostacolano il flusso di sedimenti; (3) attività di escavazione, che è continuata (seppure a tassi nettamente inferiori rispetto ai decenni precedenti) e che è ancora in atto. si può pertanto dire che nel caso del f. panaro il mancato recupero morfologico è sostanzialmente legato alla perdurante mancanza o scarsità di sedimenti tali da favorire una inversione di tendenza. il f. cecina per alcuni aspetti si differenzia dai precedenti, in quanto sembra che le risposte morfologiche stiano avvenendo con un certo ritardo rispetto agli altri due casi di studio, presumibilmente perché la fase di escavazione di sedimenti più intensa è stata leggermente successiva. un altro fattore importante può essere legato alle condizioni di energia e di trasporto solido di questo corso d'acqua, che è caratterizzato da minori portate liquide e soprattutto minori portate solide, come testimoniato dalla larghezza iniziale più ridotta e dalla stessa morfologia iniziale. l'energia del corso d'acqua ed il trasporto solido al fondo relativamente bassi rispetto ad altri casi può ritardare la riattivazione di processi erosivi ed il recupero morfologico. l'attuale tendenza sembra verso un ulteriore restringimento ed accentuazione dei processi di sviluppo di meandri, attraverso i quali l'alveo tende ad aumentare la propria sinuosità in risposta di un deficit ancora esistente di portate solide rispetto alla capacità di trasporto. le erosioni di sponda, associate al processo di sviluppo di meandri, stanno tuttavia favorendo un rifornimento di nuovi sedimenti che potrebbero quindi nei prossimi anni invertire la tendenza del fondo e favorire un arresto del processo di restringimento. 6. conclusioni le principali conclusioni che si possono trarre da questo studio sono elencate di seguito. 1. i casi di studio analizzati tendono a confermare alcune delle osservazioni fatte in studi precedenti (surian & ri n a l d i, 2004; ri n a l d i et al., 2005a), consentendo tuttavia di avere una casistica più ampia tale da contribuire ad un maggiore chiarimento di alcuni aspetti. 2. per quanto riguarda l'evoluzione tra fine 1800 e anni '90, si conferma l'esistenza di due fasi successive di evoluzione, dove l'incisione del fondo ed il restringimento dell'alveo attivo sono avvenuti pressoché in contemporanea e con intensità diverse nelle due fasi. 3. la portata solida al fondo appare essere la variabile guida più importante nel determinare queste tendenze evolutive. 4. la fase attuale di allargamento appare invece meno chiara rispetto a quanto ipotizzato precedentemente, ed è piuttosto definibile come una fase di parziale recupero morfologico, caratterizzata da oscillazioni di larghezza piuttosto che da una tendenza univoca all'allargamento. 5. in alcuni casi tale fase di recupero morfologico è assente o tuttora incerta: ciò può essere legato a varie ragioni, quali (a) un intervallo di tempo più breve rispetto alla fase di massima escavazione; (b) una pressione antropica più forte (f. panaro) che in alcuni casi determina una asportazione di sedimenti ancora significativa; (c) caratteristiche naturali dell'alveo (minore energia e minore trasporto solido al fondo) che determinano una più lenta reazione del corso d'acqua. ringraziamenti ricerca finanziata dal miur nell'ambito del progetto prin 2005 “dinamica recente ed attuale di alvei fluviali in italia centro-settentrionale: tendenze evolutive, cause ed implicazioni applicative” (responsabile nazional e: nico la s ur ian , r esp on sa bile u.o . fir en ze: massimo rinaldi) e del programma miur 2003-07 “incentivazione alla mobilità di studiosi stranieri e italiani residenti all'estero” (liliana b. teruggi). si ringraziano g. doretti e l. bellacci per gli importanti contributi relativamente alle misure effettuate su f. magra, f. vara e f. panaro. si ringrazia f. vannacci del laboratorio di sedimentologia del dipartimento di ingegneria civile e 301dinamica recente ed attuale di alvei ... ambientale di firenze per le analisi granulometriche dei sedimenti del fondo. si ringraziano infine m. marchetti e p.c. aucelli per aver contribuito a migliorare l'articolo attraverso i loro commenti costruttivi. bibliografia ag n e l l i a., bi l l i p., ca n u t i p. & ri n a l d i m. (1998) dinamica evolutiva recente dell'alveo del fiume arno monografia cnr-gndci, pubblicazione n° 1739, pacini editore, pisa, 191 pp. billi p. & rinaldi m. (1997) human impact on sediment yield and channel dynamics in the arno river (central italy) in: walling d.e. & probst j.l. (eds), human impact on erosion and sedimentation, iahs publ.no. 245, 301-311. br a g a g. & ge r v a s o n i s. (1989) evolution of the po river: an example of the application of historic m a p s in: petts, g.e., moller, h., roux, a.l. (eds.), historical change of large alluvial rivers: western europe, wiley, pp. 113-126. bunte k. & abt s.r. (2001) sampling surface and subsurface particle-size distributions in wadable graveland cobble-bed streams for analyses in sediment transport, hydraulics, and streambed monit o r i n g. u.s.department of agriculture, forest service, r ocky mou nt ain r esearch st ation , general technical report rmrs-gtr-74, 428 pp. castiglioni g.b. & pellegrini g.b. 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(2004) channel adjustments in response to human alteration of sediment fluxes: exa mpl es fr om it a li an ri ver s i n: sed imen t transfer through the fluvial system, proceedings symposium held in moscow, august 2004, iahs publ.288, 276-282. surian n. (1999) channel changes due to river regulation: the case of the piave river, italy earth surf. process. landforms, 24, 1135-1151. wo l m a n m.g. (1954) a method of sampling coarse river-bed material. am.geophys.union.trans., 35, 951-956. 302 ms. ricevuto il 7 dicembre 2007 testo definitivo ricevuto il 17 marzo 2008 ms. received: december 7, 2007 final text received: march 17, 2008 m. rinaldi et al. imp.coratza&giusti methodological proposal for the assessment of the scientific quality of geomorphosites paola coratza & cecilia giusti dipartimento di scienze della terra, università di modena, largo s. eufemia, 19, 41100 modena (italy) email: coratza.paola@unimore.it abstract: p. coratza & c. giusti, methodological proposal for the assessment of the scientific quality of geomorphosites. (it issn 0394-3356, 2005). the method proposed has been elaborated for assessing the scientific quality of geomorphosites. this method is quantitative, but a series of qualitative guide lines has been elaborated, in order to give a support for the attribution of values. scientific quality is calculated considering a series of parameters: expert’s knowledge (educational value and research value); areal extent; rarity; degree of conservation; exposure and an added value (related to the importance that the asset has for non-geomorphological aspects that nevertheless can increase its scientific value). afterwards, each parameter had to be weighted. this methodology could become a useful tool for optimizing decisional processes within the framework of territorial planning, environmental impact assessment and protection of the natural heritage. riassunto: p. coratza & c. giusti, proposta metodologica per la valutazione quantitativa della qualità scientifica di geomorfositi. (it issn 0394-3356, 2005). viene illustrata una metodologia per la valutazione quantitativa della qualità scientifica dei geomorfositi. questa proposta metodologica vuole essere un esempio di come si possa arrivare a valutazioni di tipo quantitativo, al fine di poter rendere la procedura di valutazione più obiettiva possibile, attraverso ragionamenti logici e espressioni qualitative. in particolare la qualità scientifica (q) del geomorfosito viene calcolata considerando una serie di parametri, alcuni strettamente legati alla connotazione scientifica del bene, altri indirettamente. questi parametri sono: la conoscenza dell’esperto, l’estensione areale, la rarità, il grado di conservazione, l’esposizione e il valore aggiunto. successivamente si procede all’attribuzione di un peso ad ogni parametro e alla quantizzazione della qualità scientifica del bene mediante una formula. la metodologia proposta è uno strumento utile per ottimizzare il processo decisionale nel campo della valutazione d’impatto ambientale (via), della pianificazione territoriale e della salvaguardia del patrimonio geologico. keywords: geomorphosites, assessment, gis. parole chiave: bene geomorfologico, valutazione, gis. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 307-313 1. introduction according to the definition given by panizza (2001), a geomorphosite is a landform with particular and significant attributes which qualify it as a component of the cultural heritage (in a wide sense) of a given territory. attributes which can confer value to a geomorphosite are the scientific, cultural (in a strict sense), socioeconomic and scenic attributes. therefore, with this meaning geomorphosites make up the landscape, habitat, elements of geodiversity, knowledge of the dynamics of the earth’s past, memory of biological evolution and man’s life from its very beginning, and essential resources for economic and scientific development. as such, geomorphosites deserve to be treated with a correct and appropriate management and conservation policy. in the past few years the ever-growing interest in cultural and environmental assets has underlined the demand for operators possessing adequate tools for the correct assessment, conservation and management of all these assets. hence the need to select those aspects of the landscape that more than any others deserve to be identified, known and safeguarded. indeed, only by recognizing the intrinsic value and hierarchic rank of each single element with respect to all the objects found within the system considered, will it be possible to guarantee the correct policy of environmental management (scarelli & poli, 1999). for this purpose, a quantitative assessment of geomorphological assets must be carried out in order to compare these assets or other environmental and non-environmental assets and select them, especially within the framework of territorial planning or environmental impact assessment (eia) procedures. all these approaches are necessary in order to develop possible strategies and define priorities and scales of values. in literature numerous methods are described for the quantitative assessment of landforms. the earliest go back to the 1970s and were generally developed by scholars from english-speaking countries, in particular from the united states. worthy of note are the assessment procedures by linton (1968), leopold (1969) and fines (1968). some of these propose morphometric measurement methods of diverse landscape components which are considered representative of the scenic quality of a landscape. others are more subjective and concern the perception of a whole landscape in quantitative terms (panizza & piacente, 2003). nevertheless, the limits of these assessment procedures are considerable, because they are either too subjective or based on an unnatural subdivision of geomorphological assets. starting from these preliminary remarks, an experimental methodology for a quantitative assessment of 308 p. coratza & c. giusti the scientific quality of geomorphological assets was defined and applied to a study area of the modena province plain (emilia-romagna region), which was chosen as an example area. the method here illustrated was set up by utilising gis techniques, which are the most suitable instrument for the implementation of a dynamic, updateable and ductile system for the selection, census, mapping and quantitative analysis of geomorphological assets. in addition, this system can be used in specific applications such as environmental impact assessment, territorial planning and conservation of natural heritage (coratza & giusti, 2003). in particular, gis techniques allowed data and attributes relative to the assets described in the study area to be linked to the ctr topographic map at a 1:25,000 scale in raster format. furthermore, by means of this software a new system was created, capable of comprehending the collection, modelling and analysis of data produced in the previous phases. it can therefore be a useful instrument for optimising decisional procedures in the field of territorial planning and safeguard of geological heritage. 2. methodology the proposal here presented is meant to offer an example of how quantitative assessments can be attained by means of logical reasoning and qualitative expressions. in particular, the scientific quality of an asset is evaluated by means of several parameters, some of which are directly linked to the scientific identity of the asset whereas others are only indirectly related to it. the elaboration of this methodology is based on several previous investigations (panizza et al., 1995; barba et al., 1997, rivas et al., 1997; bertacchini et al., 1999; giusti & gonzalez, 2000) and can be considered a useful tool in territorial planning and environmental impact assessment. this methodology, directed to geomorphological assets and applied by using the “ilwis 2.2” and “arcview 3” geographical information systems (gis), can be subdivided into four phases: geog r a p h i c g e o m o r p h o l o g i c a l study of the area considered, selection of assets, assessment of scientific quality, and calculation of impacts. 2.1. geographic-geomorphological setting of the study area the first investigation phase consisted of bibliographic research on the most significant scientific studies carried out on this topic. the research allowed reconstruction of the evolution and transformations occurring in historical times in the modena plain. furthermore, the interpretation of multiscalar and multitemporal aerial photographs and field surveys allowed an updated geomorphological map and a digital terrain model (dtm) of the modena plain to be realised. these documents are indispensable for selecting and mapping geomorphological sites. the modena plain is located in the south-central portion of the po plain and is bounded to the north by the province of mantova, to the east by the provinces of ferrara and bologna, to the south by the apennine foothills and to the west by the province of reggio emilia. the study area, which covers a total extension of about 1348 km2 (fig. 1), is represented in the following emilia-romagna ctr sheets at a 1:25,000 scale: 183 ne, 183 se, 183 so; 184 ne, 184 se, 184 so, 184 no; 185 so; 201 ne, 201 se, 201 so, 201 no; 202 ne, 202 so, 202 no; 219 ne, 219 se, 219 no, 219 so; 220 no. the territory under investigation stretches from north to south at elevations between 175 m to 7 m a.s.l. and, from the altitude viewpoint, can be subdivided into high, middle and low plain (various authors, 1997). the high plain is comprised between the apennine foothills and the via emilia, with elevations of 175 m to 50 m and corresponds to the alluvial fans of the main apennine watercourses. the middle plain is comprised between the via emilia and the 20 m contour line. the low plain is comprised between the 20 m and 7 m contour lines. the morphological evolution of the modena plain has mainly been conditioned by the evolution of the two main rivers that cross it: the river panaro, which flows along the eastern extremity of the province’s territory and the river secchia, which flows along the western extremity. indeed, numerous landforms occurring all over the territory result from present hydrography and ancient hydrography: fluvial ridges, ancient riverbeds, inundation fans, terraces, meanders, water springs etc. (castaldini, 1989). however, in more recent decades another element has increasingly conditioned the landscape: man with his various activities such as fig. 1 map of the study area. inquadramento dell’area di studio. quarrying, hydraulic works (e.g., meander cuts, artificial canals, flood mitigation structures) and urban development. 2.2. selection of geomorphological assets the selection of geomorphological assets was made by starting from the geomorphological vectorial map of the modena plain and from the dtm. both these documents were elaborated by means of gis ilwis 2.2 and arcview 3 programmes. this dtm, equipped with a shadow filter (fig. 2), can reconstruct the natural relief trend since contour lines (difference in altitude: 1 m) were traced without considering points corresponding to anthropogenetic structures (giusti, 2001). in addition, dtm is an indispensable tool for accurate reconstruction of plain area morphology and for a detailed representation of negative structures, such as hollow areas, and positive ones, such as rises. subsequently, a georeferenced map (coordinate system: utm) was realised with polygons representing the geomorphological assets of the modena plain (fig. 3). finally, a table of attributes containing both the data inherent to the assets’ own characteristics and their quantitative assessment, was associated with this map (fig. 4). thirteen assets were eventually selected: examples of i) fluvial meanders of the rivers secchia and panaro, which are now rare forms of the landscape owing to artificial straightening; ii) fluvial rises (gavello and ramo della lunga), which in most cases were flattened by human activities; iii) ancient, abandoned meanders of the rivers secchia and panaro with vegetation typical of wet areas; iv) water springs found at the boundary between highly pervious deposits and almost impermeable ones; only few of these springs survive owing to the overdraught from groundwater; v) fluvial terraces, both climatic and morphological, found along the boundary between the first apennine reliefs and the upper plain. 2.3. assessment of the scientific quality of geomorphological assets in order to make this assessment procedure as objective as possible, guide-lines are recommended for an easy choice and subsequent assessment of a particular asset. an important starting point is the geological and geomorphological knowledge of the study area. in particular, the scientific quality (q) of a geomorphological assets should be evaluated by means of several parameters, some of which are strictly 309methodological proposal for ... linked to the asset’s scientific specification whereas others are only indirectly connected to it. these parameters are: • experts’ knowledge (ce), which is linked to the geomophosite’s value for scientific research (s) and educational value (d); • area (a), related to the total area occupied by similar geomorphosites present in the stretch of territory considered; • rareness (r), related to the quantity of similar geomorphosites present in the stretch of territory considered; • degree of conservation (c), which depends on both natural and anthropogenetic factors; • exposure (e), in relation to visual impact; • added value (z), which is linked to the importance a geomorphosite assumes owing to non-geomorphological aspects which, nevertheless, increase its scientific value (e.g., tourism, ecological characteristics etc.). eventually, a value will be assigned to each parameter after it has been adequately weighted. scientific quality (q) is calculated by means of the following formula: q = ss + dd + aa + rr + cc + ee + zz where: s, d, a, r, c, e, z are the values and s, d, a, r, fig. 2 digital terrein model (dtm) with shadow filter. modello digitale del terreno (dtm) con filtro shadow. 310 c, e, z the respective weights. the latter, which range from 0 to 1, should be assigned to each parameter according to the guide-lines suggested. 1. experts’ knowledge (ce): experts are requested to express their opinion on two specific aspects which qualify geomorphosites from the scientific standpoint: 1) value for scientific research (s) and 2) educational value (d). 1.1. value for scientific research (s) 0.25 = low 0.50 = medium 0.75 = high 1.00 = very high the geomorphosite value for scientific research (s) can never be nil, otherwise a geomorphosite could not be considered as such. the value for scientific research should be assigned by considering the following guide-lines: • number and quality of the scientific publications concerning a geomorphosite; • whether there are research programmes in progress concerning in some way a specific site; • how representative a geomorphosite can be for the evolutional reconstruction of the territory it is inserted in; • whether a geomorphosite is important for the history of geomorphology in general; • the added value that the study of a geomorphosite can give to scientific research. 1.2. educational value (d) 0.00 = nil educational value 0.25 = low 0.50 = medium 0.75 = high 1.00 = very high the educational value should be determined by considering the following guide-lines: • representativeness of a particular form or process; • whether a given geomorphosite is quoted in educational textbooks as an asset of a certain importance; • whether a given geomorphosite is inserted in some tourist/educational itinerary and which is the educational level of such an itinerary; • whether it is known also outside the scientific world; • a geomorphosite is considered as having an educational value even if no educational material has so far been created on it. 2. area (a) this parameter is calculated as the area of the geomorphosite divided by the total area occupied by all the geomorphosites of the same type in the area considered, expressed as a percentage. 0.25 = <25% of the total area 0.50 = 25 to 50% of the total area 0.75 = 50 to 90% of the total area 1.00 = 90 to 100% of the total area the area value should be attributed by taking into account the following observations: p. coratza & c. giusti fig. 3 distribution of geomorphological sites in the study area. carta dei beni geomorfologi nell’area di studio. 311 • differently from other geological assets, the greater a geomorphosite is, the higher is its value. 3. rareness (r) rareness is assessed according to the quantity of similar elements present in the territory investigated. 0.25 = presence of numerous similar elements in the territory 0.50 = several similar elements in the territory 0.75 = very few similar elements in the territory 1.00 = unique example the rareness value should be assigned by following these guide-lines: • the rareness of a geomorphosite is a very important factor, especially if it is affected by eia or territorial planning procedures; • rareness increases if the geomorphosite bears witness to a morphoclimatic environment different from the present one. 4. degree of conservation (c) this parameter (c) may depend on both natural and anthropogenetic factors. 0.25 = poor state of conservation 0.50 = fair state of conservation 0.75 = good state of conservation 1.00 = excellent state of conservation the degree of conservation should be assigned by considering the following guide-lines: • the natural degree of degradation affecting a geomorphosite; • whether there are anthropogenetic elements which have altered or partially destroyed it; • presence of acts of vandalism; • whether there are structures that protect it from either natural or anthropogenetic agents. 5. exposure (e) exposure is considered as the visibility of a methodological proposal for ... fig. 4 zoom on the map of geomorphological sites and associated table. zoom sulla carta dei beni geomorfologici e tabella associata. 312 geomorphosite. 0.25 = the geomorphosite is heavily penalized 0.50 = the geomorphosite is penalized 0.75 = the geomorphosite is not particularly penalized 1.00 = the geomorphosite is not penalized at all the degree of exposure should be assigned by considering the following guide-lines: • a geomorphosite is suffocated by human development and, in order to see it properly, one must go very close to it; • reaching a geomorphosite may be very difficult; • presence of human structures which disturb the sight of a geomorphosite from far away; • presence of human structures which disturb the sight of a geomorphosite from a close position; • a geomorphosite is visible from all visual angles; • a geomorphosite is located in a panoramic point and emerges over the surrounding landscape. 6. “added value” (z) added value (z) is the “level of awareness” of a geomorphosite as such, owing also to non-geomorphological features, although geomorphology remains the main conditioning factor. 0.00 = nil added value 0.25 = added value of low importance, at a level of local curiosity 0.50 = added value of fair importance 0.75 = added value of high importance 1.00 = added value of fundamental importance, without which a specific asset would lose a considerable amount of its geomorphological value the added value should be assigned by considering the following guide-lines: • the geomorphosite has also a certain ecological and/or naturalistic value; • around the geomorphosite there are geological elements that further “enrich” it; • the geomorphosite has a certain tourist-economic value; • the geomorphosite has a certain historical-cultural value; • the geomorphosite lies within a protected area. the q value thus obtained is therefore normalised in order to obtain values of 0 to 1, according to the formula: q = qn / qmax. where: qn = scientific quality of a geomorphosite and qmax = maximum value that a geomorphosite can express. the values obtained are listed in tab. 1. 3. final remarks the proposed methodology makes use of gis for a quantitative assessment of geomorphological assets because it is a useful tool for optimising the decisionmaking procedure in territorial planning and in safeguarding geological heritage. the method developed in this work can be applied to advantage particularly in plain areas where anthropization has reached extreme levels. it can also counteract the widespread but mistaken belief that the landscape of the plain lacks any kind of interesting morphological elements. it must, however, be said that although the proposed methodology is quantitative, there is inevitably a degree of subjectivity in the assessment and quantification of environmental elements as their true value cannot really be measured. moreover, the allocation of values to the parameters used largely depends on the experience and sensitivity of the expert involved in assessment. the scientific quality of an asset is a purely indicative numerical quantity which can be subject to variations determined by the subjectivity of the operators p. coratza & c. giusti tab. 1quantitative assessment of the scientific quality of the geomorphological sites. valutazione quantitativa della qualità scientifica dei beni geomorfologici. and the general characteristics of the area under examination. but in spite of this, there is a real attempt to express each geomorphological asset’s scientific importance numerically so as to be able to compare them, even when there is some discrimination due to scientific dishomogeneity. in this context, the correct classification of natural and geomorphological assets together with an evaluation of their vulnerability is essential if we want to analyze the relationship between human activities and natural processes involving the modelling of the physical environment. this approach is an indispensable part of environmental impact assessment procedures, especially in the case of territorial priorities. in order to obtain the best results, it is advisable to have the method applied by a group of experts, acting independently, in order to give an estimate of each result, for example, by utilising the delphi method (balkey, 1969). references barba f.j., remondo j., & rivas v. (1997) propuesta de un procedimiento para armonizar la valoración de elementos del patrimonio geológico zubia, n. 15, pp. 11-20. bertacchini m., giusti c., marchetti m., panizza m. & pellegrini m. (eds.) (1999) i beni geologici della provincia di modena artioli editore, modena, 104 pp. coratza p. & giusti c. (2001) gis e valutazione di beni geomorfologici: un esempio nella pianura modenese (emilia romagna) geostorie, bollettino e notiziario del centro italiano per gli studi storicogeografici, università di firenze, cd-rom. castaldini d. (1989) evoluzione della rete idrografica centropadana in epoca protostorica e storica atti del convegno nazionale di studi “insediamenti e viabilità nell’alto ferrarese dall’età romana al medioevo” cento 8-9 maggio 1987. accademia delle scienze di ferrara e centro studi “g. baruffaldi” di cento, pp. 113-134. giusti c. 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(1999) quale strategia per una difesa attiva della natura?in: g. poli (ed.), geositi testimoni del tempo, regione emilia-romagna, bologna, pp. 100-103. various authors (1997) 2a relazione sullo stato dell’ambiente nella provincia di modena, provincia di modena, modena, mucchi editore. 313methodological proposal for ... sess 1_160211.pub il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 comparing marine geology and coastal geomorphology vertical tectonic data, a case study between acquedolci and patti (messina) valeria lo presti 1, maurizio gasparo morticelli 1, attilio sulli 1, fabrizio antonioli 2 & raimondo catalano 1. 1 dipartimento di geologia e geodesia, università di palermo. 2 enea casaccia, roma. corresponding author: v. lo presti <valeria.lopresti@unipa.it> abstract: lo presti v. et al., comparing marine geology and coastal geomorphology vertical tectonic data, a case study between acquedolci and patti (messina). (it issn 0394-3356, 2011) the study of new data on vertical movements show a complex geologic response in a restricted sector of coastal area between acquedolci and patti (north-eastern sicily). different surveys allowed to the recognition of morphological, biological and archaeological markers of paleo-sea level. the analysis of these markers and the absolute datings performed, allowed to reconstruct the history of vertical deformation of this sector but only the comparison among coastal geomorphological data and marine geological data of platform-scarp continental system associates, allowed to find the necessary keys words to explain the geologic complexity of this sector. riassunto: lo presti v. et al., dati di geomorfologia costiera e geologia marina a confronto nella valutazione di tassi verticali nel quaternario. il caso della sicilia nord-orientale nel settore fra acquedolci e patti (messina). (it issn 03943356, 2011) lo studio di nuovi dati sui movimenti verticali mostra una complessa risposta geologica in un settore ristretto della fascia costiera fra acquedolci e patti (sicilia nord-orientale). diverse campagne di indagine hanno portato al riconoscimento di indicatori morfologici, biologici e archeologici del paleo livello del mare. l’analisi di questi markers e le datazioni assolute eseguite, hanno permesso di costruire un quadro sulla storia della deformazione verticale di questo settore ma solamente il confronto fra i dati geomorfologici costieri e gli ambienti marini di piattaforma e scarpata continentale ad essi associati, ha permesso di trovare le chiavi di lettura necessarie a spiegare la complessità geologica di questo settore. key words: coastal geomorphology, tectonic uplift, north-eastern sicily. parole chiave: geomorfologia costiera, sollevamento tettonico, sicilia nord-orientale.  1. introduction the calabrian arc records one of the major quaternary vertical movement in the whole mediterranean region. data on vertical move ments calculated for the coastal area along the north-sicilian continental margin indicate that, from east to west, a strong variation of vertical rates of uplift are recognized during both middle-late pleistocene and holocene. vertical position of sea-level, related deposits and morphologies provide useful markers to estimate uplift rates (lambeck et al., 2004; ferranti et al., 2006, antonioli et al., 2009). in the northwest sicily coast the uplift rates estimated for the holocene are greater than those estimated at the same point from the last interglacial (lig, 125 ka) (antonioli et al., 2006). the measured uplift misured appear as the result of two different processes, due to a “continuous regional” component and an "episodic coseismic” component respectively (ferranti et al., 2007). this study, based on published (ferranti et al., 2010) and new data, deals with the vertical tectonic movements calculated in the sector between acquedolci and patti (sicily northern coast). we focus our attention on the eastern sector of the sicilian northern coast and particularly immediately to the west of the vulcanotindari fault system, where several evidences of vertical movements during the pleistoceneholocene have been recognized. in this active sector the tectonic lineaments show different trends (nicolich et al., 1982; nigro & sulli, 1995) both onland (monaco & tortorici, 2000; atzori et al., 1978) and offshore (gabbianelli et al., 1996; cuppari et al., 1999). the occurrence of both oblique and normal fault systems and the alternation of rocks with different competence, as the hercynian metamorphic basement, its meso-cenozoic carbonate and oligocene-miocene terrigenous cover and 38 40 39 pleistocene deltaic ore and gravels (carbone et al., 1998), determine a complex geomorphological setting. the morphological response to the active tectonics is very different onland and in the offshore areas, due to the occurrence in the submerged areas of preserved structures, which are obliterated, eroded or covered in the exposed areas, as well seismic reflection data reveal trends and mechanisms of the relative motion from land to sea, through the analysis of the recognized fault systems. on the other hand the outcropping biological and geomorphological markers provide to estimate tectonic uplift rates, which are not allowed in the marine areas. 2. data analysis in the coastal sector from acquedolci and patti geomorphologic survey provided new data on quaternary uplif rates. it induced us to divide this area, close to the capo d’orlando promontory, in two sector with different deformational response to the regional tectonics, as evidenced by the different distribution of the pleistocene marine terraces. between capo d’orlando and patti marine abrasion surface are infrequent as well the marine terrace deposits, which are difficult to agedate. on the contrary to the west of capo d’orlando the pleistocene marine terraces morphologies are well preserved. between acquedolci and capo d'orlando we recognized a well preserved set of four orders of marine terraces. the terrace located at about 40 m (rocca scodoni) presents a marine deposit; the inner margin, located at 45-50m, is constituted by a cliff with several lithodomus holes. here a shell of spondylus s.p. in physiologic position was found; the u/th analysis on shell provides (with large error bar) an mis 5 age (between 100 and 125 ka) (scicchitano et al., 2011; gasparo morticelli et al., 2010). for this sector we estimate the tectonic uplift rate between 0.36-0.5 mm/yr. to the east of patti several auhors calculated regional uplift rates between 0.62 and 0.67 mm/yr from the last interglacial (ferranti et al., 2006). a few kilometers east of rocca scodonì, archaeological markers occur (scicchitano et al., 2011) along the coastal sector est of capo d’orlando. here an ancient quarry of grinding wheels for oil has been found. they present subcircular holes in the materials coming from the upper oligocene-lower miocene stilo-capo d’orlando deposits (carbone et al., 1998). the tectonic uplift was evaluated as the difference between the observed local paleo-sea level position and the predicted sea-level curve for the same locality. the resulting uplift rates of 0.36 mm/ yr (scicchitano et al., 2011) suggests similar tectonic uplift rates of rocca scodoni but relative to the holocene. between capo d'orlando and capo calavà, we studied the brolo island, located in the central part of a small bay; it is a "lentil" of metamorphic rocks emerging above the 14-18 m deep seafloor, at 450 m from the coastline. a detailed geomorphological sub aerial and underwater survey was conducted, which led to discovery a fossils-bearing conglomerate, in protected trays at 3.5 m from sea level, and well preserved lithophaga holes at about 70 cm from sea level. radiocarbon analysis on a gastropod found in the marine conglomerate gave us an age of 4745 yr +/59 (4965 years +-70 cal bp). if we compare this data with the predicted local sea level curves (lambeck et al., 2011), we obtain an uplift rate about 1.5 mm/yr (lo presti et al., 2010), which is higher than that calculated for the last interglacial and for the holocene in the study of archaeological rest. westward of capo calavà a "suspended" alluvial fan outcrops in a cliff a few meters back to the coastline. at the base of the cliff, around 1.3 meters above sea level, we recognize the stratigraphic contact between the alluvial fan deposit and the paleo-beach. the alluvial fan is incised in the highest part by a little river that flows into the sea with a fall of around 12 meters of height. in the patti area, near mongiove promontory, lithodomus holes on metamorphic rocks can be observed between 2.2 and 3.5 meter above sea level. also not allowing the calculation of tectonic uplift rates, the presence of a suspended alluvial fan and the recovery of lithodomus holes constitute a further evidence of effects of vertical tectonic movements along the coastal areas. the analysis of marine geology data demonstrates that the active tectonics determines the morphological feature of the continental shelf-slope system (lo presti, 2010). multibeam data evidenced structures connected to different faults systems, such as the submarine canyons which incised the continental slope in the acquedolci to patti offshore. most of the canyons are the continuation of fluvial beds (“fiumare”), demonstrating the occurrence of sea-land tectonic lineaments. mainly in the capo calavà sector submarine canyons are characterized by v-shaped valleys, very incised gullies and steep flanks, testifying the role of active tectonics. marine geology data evidenced also tilted ne-ward submerged surfaces, indicating existing structural movements, interesting only restricted areas, a few kilometers wide. comparing marine geology and coastal geomorphology ... 40 ms. received: testo ricevuto il 3. conclusions geomorphological surveys, radiocarbon analysis and marine geology data in the northwestern sector of peloritani mountains and its offshore evidenced significant assessment about uplift rates in the quaternary. field data reveal from capo d’orlando towards the east a sharp increase of the tectonic uplift rates during the holocene, with respect to the values calculated from the last interglacial. very different uplift rates mainly in the holocene in very close areas: 0.36 mm/yr (scicchitano et al. 2011) and 1.5 mm/yr (lo presti et al. 2010) distant only about 10 kilometers, has evidenced the role of tectonic lineaments, acting as releasing features during the holocene. seismic reflection profiles support this assumption, showing the metamorphic basement strongly dissected by high-angle faults, which at place determines the occurrence of emergent rock bodies (e.g. the brolo island). more the morphobathymetric data show tilted surfaces, suggesting the occurrence of “restricted regions” in the coastal-marine sector with different geological behavior as response to prominent tectonic releasing bands, determining their horizontal and vertical movements. references antonioli f., kershaw s., renda p., rust d., belluomini g., radtke u. & silenzi s. 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(2011) – millstones as indicators of relative seal level changes in northern sicily and southern calabria coastlines, italy. quaternary int., in press. v. lo presti et al. january 15, 2011 15 gennaio 2011 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 20%) /calrgbprofile (srgb iec61966-2.1) /calcmykprofile (u.s. web coated \050swop\051 v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.0000 /colorconversionstrategy /cmyk /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 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can be opened with acrobat and adobe reader 5.0 and later.) >> /namespace [ (adobe) (common) (1.0) ] /othernamespaces [ << /asreaderspreads false /cropimagestoframes true /errorcontrol /warnandcontinue /flattenerignorespreadoverrides false /includeguidesgrids false /includenonprinting false /includeslug false /namespace [ (adobe) (indesign) (4.0) ] /omitplacedbitmaps false /omitplacedeps false /omitplacedpdf false /simulateoverprint /legacy >> << /addbleedmarks false /addcolorbars false /addcropmarks false /addpageinfo false /addregmarks false /convertcolors /converttocmyk /destinationprofilename () /destinationprofileselector /documentcmyk /downsample16bitimages true /flattenerpreset << /presetselector /mediumresolution >> /formelements false /generatestructure false /includebookmarks false /includehyperlinks false /includeinteractive false /includelayers false /includeprofiles false /multimediahandling /useobjectsettings /namespace [ (adobe) (creativesuite) (2.0) ] /pdfxoutputintentprofileselector /documentcmyk /preserveediting true /untaggedcmykhandling /leaveuntagged /untaggedrgbhandling /usedocumentprofile /usedocumentbleed false >> ] >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice imp.castaldini& geo-tourist map of the natural reserve of salse di nirano (modena apennines, northern italy) doriano castaldini1, jairo valdati1, dorina camelia ilies2 & cosmin chiriac2 with contributions by isabella bertogna3 1dipartimento di scienze della terra, università di modena e reggio emilia, modena, largo s. eufemia 19, modena, italy; e-mail: castaldini.doriano@unimore.it 2department of geography, tourism and territorial planning, university of oradea, armata romana 5, oradea, romania. 3riserva naturale regionale delle salse di nirano, comune di fiorano modenese, piazza c. menotti 1, fiorano modenese, italy. abstract: d. castaldini et al., geo-tourist map of the natural reserve of salse di nirano (modena apennines, northern italy). (it issn 0394-3356, 2005). this article illustrates the criteria and methods applied for implementing a geo-tourist map of the natural reserve of “salse di nirano”. this map is an “original” cartographic elaboration in the field of italian thematic mapping. the “salse” are small mud volcanoes genetically linked to the ascent to the surface of salty and muddy waters mixed with gaseous (methane) and, to a lesser extent, fluid hydrocarbons along tectonic discontinuities produced by overthrusting along the front of the apennine chain. the mud volcanoes of the modena apennines have been known since a long time and have always aroused great interest: they are described in many papers, starting as early as pliny the elder, in around 50 a.d. since the “salse di nirano” are one of the best developed mud-volcano phenomena of the entire italian territory and among the largest in europe, in 1982 a natural reserve was established in the area by the emilia-romagna region; the reserve territory covers a total area of about 200 ha with elevations ranging from 140 to 308 m. by means of arcview gis computer program a digital terrain model (dtm), a geomorphologic map and a geo-tourist map have been elaborated and will be displayed at the visitor center of the reserve. the orographic arrangement of the territory is effectively illustrated by dtm, which was implemented on the basis of altimetric data of the regional technical map (ctr) of the emiliaromagna region. the detailed geomorphologic features are represented in a geomorphologic map, elaborated on the basis of bibliographic research, interpretation of aerial photographs and field survey. in the study area, where silty-clay soil types (plio-pleistocene in age) crop out, landforms and deposits resulting from the endogenetic activity of the mud volcanoes, running water, gravity, anthropogenic activities and polygenetic landforms were recognized. the geo-tourist map was derived (with appropriate simplifications and integration) from the geomorphologic map. the geo-tourist map combines the most evident geomorphologic features (mud volcanoes, badlands, landslides, anthropogenetic landforms, bedrock, surface deposits, ponds, marshes etc.) – which can be observed and recognized even by non-experts – with fundamental tourist information (main roads, parking places, visitor center, excursion trails, picnic areas, panoramic points, restaurants and places to stay). the geo-tourist map and dtm are the characterizing documents of a new tourist map of the reserve (tourist-environmental map). in particular, the geo-tourist map is a foldable, pocket-size, front/rear printed map, with explanatory notes in italian and english: it was published with the financial support of the municipality of fiorano modenese. this article proves that geomorphologic research can effectively contribute to the implementation of documents and maps useful in the field of tourism. riassunto: d. castaldini et al., carta geo-turistica della riserva naturale delle salse di nirano (appennino modenese, nord italia). (it issn 0394-3356, 2005). il presente articolo illustra i criteri e la metodologia applicati per la realizzazione della carta geo-turistica della riserva naturale regionale delle salse di nirano, che rappresenta un documento “originale” nella panoramica della cartografia tematica italiana. le “salse” sono dei piccoli vulcani di fango geneticamente connessi a risalita in superficie di acqua salata e fangosa frammista ad idrocarburi principalmente gassosi (metano) e, in piccola parte, liquidi (petrolio), lungo discontinuità prodotte dagli accavallamenti frontali dell’appennino. le salse dell’appennino modenese sono note da molto tempo ed hanno da sempre suscitato grande interesse: sono state descritte in numerosissimi lavori, già a partire da plinio il vecchio nel 50 d.c. essendo il campo delle salse di nirano, uno dei fenomeni seudo-vulcanici meglio sviluppati su tutto il territorio italiano e tra i maggiori d'europa, la regione emilia-romagna nel 1982 vi ha istituito una riserva naturale che occupa una superficie totale di circa 200 ha ed è compresa fra i 140 e i 308 m di quota. per facilitare al visitatore la lettura e la comprensione del paesaggio della riserva sono stati elaborati, utilizzando il sistema informativo territoriale arcview, un modello digitale del terreno (dtm), una carta geomorfologica e una carta geo-turistica che saranno esposti al centro visite della riserva. l’assetto orografico del territorio è efficacemente reso dal dtm, realizzato sulla base dei dati altimetrici della carta tecnica regionale (ctr) della regione emilia romagna. gli aspetti geomorfologici di dettaglio sono rappresentati in una carta geomorfologica, realizzata sulla base di una ricerca bibliografica preliminare, dell’interpretazione di fotografie aeree e mediante rilevamenti sul terreno. nell’area di studio, dove affiorano esclusivamente litologie limo-argillose (del plio-pleistocene), sono state riconosciute forme e depositi legati al fenomeno “endogeno” delle salse, per acque correnti superficiali, gravitativi di versante, antropici e poligenetici. la carta geo-turistica è stata derivata (con appropriate semplificazioni ed integrazioni) dalla carta geomorfologica. la carta geo-turistica coniuga la rappresentazione dei più evidenti aspetti geomorfologici (salse, calanchi, frane, opere antropiche, litologia del substrato e depositi superficiali, specchi d’acqua, paludi ecc.), che possono essere osservati e riconosciuti anche da persone non esperte, con l’indicazione delle informazioni turistiche fondamentali (punti di accesso, parcheggi, centro visite, percorsi escursionistici, aree di sosta attrezzate, punti panoramici, punti di ristoro e di pernottamento). la carta geo-turistica e il dtm sono i documenti caratterizzanti di un nuovo depliant turistico della riserva (carta turistico-ambientale). questo nuovo documento è un pieghevole, di formato tascabile, stampato fronte/retro con note illustrative in italiano e in inglese: è stato stampato con il contributo finanziario del comune di fiorano modenese il presente articolo testimonia come la ricerca geomorfologica possa efficacemente contribuire alla realizzazione di documenti utilizzabili nel settore turistico. keywords: mud volcanoes, geomorphology, geo-tourist map, modena apennines, northern italy. parole chiave: salse, geomorfologia, carta geo-turistica, appennino modenese, italia settentrionale. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 245-255 246 d. castaldini et al. 1. foreword in the past few years several studies have been carried out both at an international (e.g., wimbledon et al., 1995; dixon, 1996; eberhard, 1997; hose, 1997; barrettino et al., 1999; johansson & zarlenga, 1999; coratza & marchetti, 2002; reynard et al., 2003) and national (e.g. carton et al., 1994; benvenuti et al., 1998; bertacchini et al., 1999; panizza, 2001; poli, 1999; piacente et al., 2000; piacente & poli, 2003) level for the preservation of geologic heritage (whose elements are defined, according to the various authors, as “geologic assets”, “geotopes”, “geosites” or “geomorphosites”) and its diffusion and appraisal also outside the realms of academic research. for a general discussion on this topic, see panizza & piacente (2003). this paper is about the “salse di nirano” geosite, which makes up the only endogenetic forms found in the modena apennines. from a general viewpoint, mud volcanoes are remarkable geologic features formed by semi-liquid and gas-enriched mud breccias extruded from deep sediment layers on the ground surface or on seafloors (cf. dimitrov, 2002 and references in it; deville & prinzhofer, 2003). mud volcanoes are known in many areas of the world; the most important ones are located in azerbaijan, mexico, venezuela, colombia, and ecuador. in europe they can be found in italy, albania and romania. although most mud volcanoes have a typical conical shape, they can assume a great variety of forms, referred to as “mud cones”, “mud lumps”, “mud diapirs”, “mud pies” etc., depending on their shape and size which, in turn, depend on the degree of mobilization initiated by pore-fluid pressures, frequency and characteristics of their activity, and viscosity of the outflowing mud. for example, the azerbaijan mud volcanoes attain a height of some 500 m. also the mud volcanoes of the modena apennines are genetically linked to the ascent to the surface of salty and muddy waters mixed with hydrocarbons along tectonic discontinuities produced by the overthrusting of the apennine chain front (illustrated in the geologic section). the name “salsa” results from the high “salt” content of these muddy waters. the shape of the ejection apparatus depends on the density of the muddy mixture: if it is dense, “cones” (single, double or multiple) of height ranging from a few decimeters to some meters may develop; if the muddy mixture is liquid, ground level “pond-shaped” mud-volcanoes (diameters ranging from a few decimeters to some meters) are formed. the mud volcanoes of the modena apennines have been known for a long time and have always aroused great interest. they were first described by pliny the elder, in around a.d. 50, in his monumental “naturalis historia”. pliny the elder described the eruption of a mud volcano in the modena district (but it is not known to which one he referred) with the much exaggerated terms of “crepitu maximo… flamma fumoque”. other scientists after him, especially in the 17th and 19th centuries, described the mud-volcano activity with the same fantastic attributes of impressiveness and spectacularity (e.g. ramazzini, 1698; spallanzani, 1795). in particular, at the end of the 19th century the abbot stoppani described the “salse di nirano” comparing them to molehills out of which noises similar to “retching” came out; he gives them the epithet of “cesspool volcanoes” (stoppani, 1873). many other authors followed (e.g. pantanelli & santi, 1896; biasutti, 1907; barbieri, 1947; mucchi, 1966 and 1968; bertolani, 1980; ferrari & vianello, 1985; bertacchini et al., 1999; castaldini et al. 2003; gorgoni, 1998 and 2003). mud volcanoes are a classical example of “geomorphologic convergence”, that is, similar forms but with different origins (panizza, 1992). in fact, although cone-shaped cones and flows are being formed and, in the specific case of salse di nirano, a caldera-like depression contains all these emissions, mud volcanoes have nothing to do with actual volcanism, although many visitors still think they have. the “salse di nirano” are one of the best developed mud-volcano phenomena of the entire italian territory and among the largest in europe. in 1982, the natural reserve of salse di nirano was established in the area by the emilia-romagna region, with the aim of safeguarding and preserving the natural and environmental characteristics of the site (tosatti, 2002). in this way, the fruition of the area for scientific, cultural, educational and recreational purposes was be attained. within the framework of investigations for assessing and appraising geosites in the italian landscape, and in collaboration with the board administering the reserve (municipality of fiorano modenese), a digital terrain model (dtm), a geomorphologic map and a geo-tourist map have been elaborated and will be displayed at the visitor center of the natural reserve of salse di nirano (named “ca’ tassi”). these should help to explain the landscape of the reserve to tourists. in particular, this article illustrates the criteria and methodology applied for implementing a geo-tourist map which combines the illustration of the most significant geologic-geomorphologic aspects with fundamental tourist information. 2. geographic and geologic outline of the study area the natural reserve of salse di nirano is located in the western sector of the modena apennine margin, which belongs to the northern apennines (fig. 1). the territory of the natural reserve covers a total area of about 200 ha with elevations ranging from 140 and 308 m a.s.l. the area where the mud volcanoes are found covers about 10 ha and is situated at the bottom of a wide subcircular depression at an altitude of about 200 m. the setting up of new structures – such as a large parking lot, a new footpath leading to the mud-volcano fields, some resting areas and a road leading to the ca’ tassi visitor center – have facilitated the fruition of the reserve, which was visited by 30,000 people in the year 2003. this influx of visitors also shows that this “small green belt” of the lower modena apennines is in a strategic position from the tourist viewpoint. as for climate, the study area is comprised within the sub-continental temperate climate with average precipitation of about 800 mm/year and average temperatures of 12 to 13 °c (see servizio meteorologico della regione emilia-romagna, 1995). 247geo-tourist map of ... from a geologic standpoint, the modena apennine margin is characterized by prevalently compressive structures which correspond to the so called “emilia folds” (pieri & groppi, 1981; castellarin et al., 1985; gasperi et al., 1989). tectonic structures have been produced by northbound translational movements (occurring mainly during the messinian and pliocene) which affected both the apennine chain and the plain which lies in front of it. these movements led to the sequence of thrusting and décollement structures and controlled to some extent the sedimentation rate in the plain (fig. 2). sediments ranging from the lower pliocene to the lower pleistocene outcrop almost continuously in this area. to the south, these deposits are usually transgressive on the ligurian units (made up of deepsea sediments followed by thick sequences of cretaceous to eocene calcareous or terrigenous turbidites); to the north, towards the po plain, they are covered by alluvial deposits of the middleupper pleistocene. in the apennine margin many faults and folds affecting the marine quaternary sediments, indicate a middle pleistocene uplift of the apennine sector with respect to the plain and a tendency of the southern structures to overthrust the northern structures (castaldini et al., 1988). the present day tectonic activity of the apennine margin is shown by earthquakes that, in this area, are mostly concentrated along the plain-hill boundary. among the most intense seismic events, the quakes of 1438 (viii mcs), 1501 (viii-ix), 1547 (viii), 1818 (vii-viii), 1971 (vii-viii) should be mentioned (cf. gruppo di lavoro cpti, 1999). in the past, some authors noted a correspondence between episodes of violent activity of the mud volcanoes and earthquakes (cf. stohr, 1869; pantanelli & santi, 1896; pellegrini et al., 1982; gorgoni et al., 1988). more recent investigations (gorgoni, 1998 and 2003) have shown that the activity of the mud volcanoes is influenced by local seismicity, some days before the occurrence of rather strong earthquakes. fig. 1 upper part: location of the natural reserve of salse di nirano (point) and of the geologic cross section of fig. 2 (line). lower part: the natural reserve of salse di nirano in the regional technical map (ctr) of the emilia-romagna region (tav. 219 no sassuolo). parte superiore: ubicazione della riserva naturale delle salse di nirano (punto) e del profilo geologico di fig. 2 (linea). parte inferiore: la riserva naturale delle salse di nirano nella carta tecnica regionale (ctr) della regione emilia-romagna (tav. 219 no sassuolo). 248 3. geomorphologic features of the natural reserve in order to offer detailed information about the physical landscape of the reserve area, a geomorphologic map and a digital terrain model (dtm) have been realized by means of arcview gis computer program. the topographic basis for their elaboration was the regional technical map (ctr) of the emilia-romagna region (1:5,000 scale) (fig. 3). the general morphologic picture of this territory is effectively provided by the dtm (fig. 4) which was computer-elaborated through the transformation of altimetric data (5 m equidistance contour lines) into a triangular irregular network (tin). by examining it, the presence of a sub-circular shaped depression, similar to a caldera, is quite evident even to nonexperts: on the floor of this depression the mud volcanoes are found. an explanation is that this form is the result of a progressive gravitational collapse due to the constant depletion of mud ejected from the vents (bertacchini et al., 1999). another hypothesis is that the depression could be the result of a collapse in correspondence of a “mud-diapir” at the end of its uplifting activity (personal communication by g. bettelli). indeed, this hypothesis seems to be more plausible, because it explains not only the depression itself, but also its sub-circular shape. also the “calanchi” (badlands) are quite evident in the dtm. these are one of the most spectacular forms of erosion, similar to badlands, of the apennine margin (fig. 5). they are typical of clayey soils and are characterized by a very fine drainage network and short, steep slopes with narrow interfluves. the dtm clearly shows that these landforms are absent only in the southern part of the reserve. furthermore, the excursion trails have been indicated in order to provide the visitor with information on their elevation development. d. castaldini et al. fig. 2 geologic cross section of the modena apennine margin and plain (after gasperi et al., 1989). q: quaternary; plms: upper-middle pliocene; pli: lower pliocene ms: upper miocene; mm: middle miocene; mi: lower miocene; l: ligurian units. profilo geologico del margine appenninico e dell’alta pianura modenese (da gasperi et al., 1989). q: quaternario; plms: pliocene medio-superiore; pli: pliocene inferiore; ms: miocene superiore; mm: miocene medio; mi: miocene inferiore; l: liguridi. fig. 3 scheme of elaboration of the various documents. schema di elaborazione dei vari documenti. fig. 4 digital terrain model (dtm) of the natural reserve of salse di nirano (modena apennines). modello digitale del terreno (dtm) della riserva naturale delle salse di nirano (appennino modenese). 249 detailed morphologic aspects are illustrated in a geomorphologic map, resulting from bibliographic research, analysis of recent aerial photographs (1994 and 1998/99) and field survey. in drawing up the geomorphologic map of the study area (fig. 6) the legend set up by gruppo nazionale geografia fisica e geomorfologia (1994) was applied with some modifications. in the reserve area only silty-clay soil types (pliopleistocene in age) crop out: the “argille del t. tiepido” (marine silty-clays) which are found nearly all over the territory and the “argille del rio del petrolio” (marine marly-clays) cropping out to the north. the study area is characterized by the presence of two systems of tectonic discontinuities (faults and/or fractures), nw-se and sw-ne oriented, respectively. these discontinuities have been identified by means of aerial photo interpretation and field observations of the mud volcanoes arrangement, which shows a clear alignment (fig. 7). the main streams are the rio chianca (which marks the western and northern boundary of the park), rio delle salse and its tributary rio serra which, as previously stated, flow in the southern sector of the reserve. in addition, some small reservoirs are also found: three ponds and four marshy areas. another four relict ponds have been completely filled by palustrine deposits. their origin is artificial as witnessed by the presence of artificial embankments downstream. the geomorphologic map (fig. 6) does not show the precise number of the mud-ejecting points but simply their location, distinguishing between cone-shaped mud volcanoes (fig. 7) and pond-shaped mud volcanoes (fig. 8). the morphology of this area is, in fact, constantly evolving with the formation of new craters whilst others cease their activity. the activity of a salsa is influenced by meteorologic factors. in summer, the activity may decrease due to the muds’ de-hydration until the possible obstruction of the up-welling channel occurs. during wetter seasons, due to the terrain softening and to the increasing methane’s pressure accumulating deeper down, the obstruction can be demolished and the activity may restart. during non-active periods, the mud volcanoes are subject to erosion by precipitation water and can be partially dismantled, until the following activity phases when they are rebuilt. the number of apparatuses can vary with time, as well as their location: in the case of nirano, the mapping and photographic documents point to a considerable steadfastness during the past one hundred years (gorgoni, 2003). during our survey, five main groups of cone-shaped mud volcanoes and three main groups of pondshaped ones were found. the clayey materials ejected from the craters cover the surrounding ground with mudflows. therefore, owing to the constant emission of mud over time, the floor of this depression is covered by fine-grained deposits up to a few meters in thickness. the main anthropogenetic landforms are found near the eastern entrance to the reserve. they are: i) an abandoned quarrying area, modeled at present by the running waters which have created the badlands, gullies and colluvial deposits; ii) a parking area for visitors and iii) an artificially flattened area corresponding to a disused farming area (a worm “farm” for anglers). furthermore, the areas affected by creep due to grazing, which are concentrated on the northern slopes of the reserve, are also shown. this man-induced process is made evident by the step-like shape of the slopes created by pasturing sheep. by reducing the grass cover of the soil, these animals have also favored the onset of solifluction. the numerous crests and watersheds have been considered as polygenetic forms. indeed, while the sub-circular crest which surrounds the mud-volcano depression is probably linked to a gravitational collapse, other watersheds were created by retrogradation of the badland heads. the landforms and deposits due to running waters are particularly widespread. nearly everywhere it is possible to observe badlands (“calanchi”) in most cases stabilized by vegetation. small earth flows, in most cases stabilized, fill the erosion furrows at the foot of the badlands; they too are shown on the geomorphologic map. also the main gullies are indicated. deposits have been indicated only where their thickness exceeds 1 m. they are mostly made up of very fine materials deposited by the main watercourses (concentrated on the floor of the small valleys of rio chianca, rio serra and rio delle salse) and colluvial deposits (particularly widespread at the foot of the northern slope of the mud volcanoes depression). geo-tourist map of ... fig. 5 the “calanchi” (badlands) of the rio chianca valley in the northern sector of the reserve. i calanchi della valle del rio chianca nel settore settentrionale della riserva. 250 d. castaldini et al. f ig . 6 g e o m o rp h o lo g ic m a p o f th e n a tu ra l r e se rv e o f s a ls e d i n ir a n o ( m o d e n a a p e n n in e s) . c ar ta g e o m o rf o lo g ic a d e lla r is e rv a n at u ra le d e lle s al se d i n ir an o ( a p p e n n in o m o d e n e se ). landslide bodies and relative detachment scarps are quite common all over the reserve; they are landslides classified as small earth flows. most landslide deposits have been colonized by spontaneous vegetation which has contributed to stabilizing them and making them poorly visible in the field. solifluction makes up a secondary process particularly widespread in the northern part of the reserve, where it has been favored by creep due to grazing. 4. geo-tourist map a geo-tourist map can be considered as a thematic map; these are maps which focus on a particular aspect (cf. sestini, 1981; mori, 1990) and, consequently, are aimed at specific categories of users. first of all, in the preparation of a thematic map, the set of data that are to be emphasized must be chosen, namely the setting up of a language and mapping system (cf. papotti, 2002). therefore, a geo-tourist map should combine geologicgeomorphologic data with tourism data. the geo-tourist map here illustrated was derived (with appropriate simplifications and integration) from the geomorphologic map and combines the most evident geologic-geomorphologic aspects with basic tourist information (fig. 3). the geo-tourist map, which was originally produced in color, is here presented in black and white (fig. 9). the goal of this study was to make a map which could be easy to read for a tourist of average education. since the immediacy of a map depends essentially on the simplicity of the symbols used, we deliberately avoided the setting up of a legend finalized to the completeness of data, which would have implied a long list of symbols. considering that the more symbols are added the more is lost in clarity, the use of symbols was limited to the essential ones. in particular, the legend was subdivided into two clearly distinct sectors. in the first sector the symbols representing geologic and geomorphologic aspects are illustrated, whereas in the second one the symbols concerning tourism information are shown. regarding the geomorphologic aspects, the geo-tourist map pinpoints all the elements of the landscape that a tourist can observe and identify. an effort was made to use simple, clear, graphically pleasing symbols with short captions, avoiding specialized terminology. in any case, the legend adopted is scientifically correct. from the practical viewpoint, using the geomorphologic map as a starting point, the following criteria of elaboration have been applied: i) as regards the mud 251geo-tourist map of ... fig. 8 pond-shaped mud volcano. salsa a “polla”. fig. 7 cone-shaped mud volcanoes. they show a clear alignment in corrispondence with a fault/fracture. salse “a cono”. esse sono chiaramente allineate lungo una faglia/frattura. 252 d. castaldini et al. f ig . 9 g e o -t o u ri st m a p o f th e n a tu ra l r e se rv e o f s a ls e d i n ir a n o ( m o d e n a a p e n n in e s) . c ar ta g e o tu ri st ic a d e lla r is e rv a n at u ra le d e lle s al se d i n ir an o (a p p e n n in o m o d e n e se ). volcanoes (“salse”) – the main attraction of the reserve – symbols graphically recalling both the “cone-shaped” forms and the “pond-shaped” ones have been adopted; ii) these symbols are shown in particularly evident dimensions, so that the tourist can immediately locate them; iii) the distinction of activity for landforms and deposits has been eliminated; iv) also faults/fractures have been cancelled from the map since they are not easily identifiable in the field; v) the less representative forms (e.g., gullies) and the most difficult ones to be recognized (e.g., slopes affected by solifluction, areas affected by creep due to grazing) have been eliminated; vi) the various types of deposits have been simplified (e.g., a single grouping for deposits due to running waters); vii) in the original version (in color) the range of colors used has been reduced. as for tourist information, in the original version (in color) this has been indicated with a particularly evident color (red), in order to be immediately recognized by the visitors. the commonly used symbols for tourist maps have also been adopted in this case. they include: i) general information (e.g., ca’ tassi visitor center, excursion trails, panoramic points along the excursion trails, picnic areas); ii) wildlife information (bird-watching points); iii) logistic information (main access roads, parking places, refreshment and overnight-stay sites, consisting of a restaurant, a holiday farm and a bed & breakfast). as previously stated, in the geo-tourist map (and in the dtm) the excursion trails are shown in order to facilitate the interpretation of the landscape and its elevation points for the tourist willing to walk along the trails suggested. the trails are as follows: 1) tour of the “salse”: this trail winds around the core of the natural reserve allowing the phenomenon of mud volcanoes to be observed from both close up and from a panoramic viewpoint. 2) walk around the ponds: this trail follows the valley floor of the rio delle salse/rio serra as far as the two artificial ponds se of pra’ rosso (where birdwatching can be practiced), then it continues upwards as far as the southernmost crest of the reserve. 3) walk from the salse depression to the chianca valley: this comprises some panoramic points from which the view of the entire mud volcanoes depression can be appreciated. along this trail it is possible to observe at close quarters the western “calanchi” of the reserve and a typical example of marsh. 4) tour of the “calanchi”: this trail follows prevalently the valley floor of rio chianca and allows the observation of several examples of badlands from below. 5. conclusions the study here described was finalized to the implementation of a digital terrain model (dtm), a geomorphologic map and a geo-tourist map of the natural reserve of salse di nirano. whereas the first two documents are common within the framework of geomorphologic studies, the geo-tourist map is an original document. the goal was to produce a map that could be easily interpreted by tourists with average education and help them to understand the surrounding landscape. therefore, since the readability of a map depends essentially on the simplicity of its symbols, only the symbols considered as essential are shown. in particular, the legend was subdivided into two clearly distinct sectors. the first sector shows the symbols representing the geologic and geomorphologic aspects, whereas the second shows the symbols regarding tourist information. all maps (geomorphologic map, dtm and geotourist map) have been implemented by means of arcview gis computer program. therefore, since these documents are presented in the digital format, they can be easily updated and/or integrated with further data. the dtm and geo-tourist map are the characterizing documents of a new tourist foldable on the reserve (tourist-environmental map). the elaboration of the foldable, pocket-size, front/rear printed touristenvironmental map has now been completed. this document, which is presented with explanatory notes in italian and english, was published with the financial support of the municipality of fiorano modenese (barozzini et al., 2004). this initiative, which is part of the activities aiming to improve the information, fruition and appraisal of the region’s natural reserve of salse di nirano, witnesses how geomorphologic investigations can effectively contribute to the creation of maps utilizable in the tourism field. acknowledgements the financial support of this study was provided by cofin 2001-03 research project (coordinator sandra piacente, dipartimento di scienze della terra dell’università di modena e reggio emilia). the authors are grateful to professors mario panizza, sandra piacente and maurizio pellegrini and to doctors paola coratza and cecilia giusti, for their critical review of the preliminary version of the geo-tourist map. references barbieri g. (1947) nuove osservazioni sulle salse emiliane riv. geogr. it., 54 pp. barozzini e., bertogna i., castaldini d., dallai d., del prete c., chiriac c., gorgoni c., ilies d.c., sala l. & valdati j. (2004) riserva naturale regionale delle salse di nirano”: carta turistico ambientale comune di fiorano-assessorato ambiente. eliofototecnica barbieri, parma. barrettino d., vallejo m. & gallego e. (eds.) (1999) towards the balanced management of geological heritage in the new millenium sociedad geologica de españa, madrid, 146 pp. benvenuti m., boni m., brancucci g., bortolami g., burlando m., costantini e., d’andrea m., gisotti g., guado g., marchetti m., massoli-novelli r., panizza m., pavia g., poli g. & zarlenga f. (1998) the conservation of geological heritage in italy: state of the art and future perspectives of the “geosites” project geologica balcanica, 28(34), pp. 117-123. bertacchini m., giusti c., marchetti m., panizza m. & pellegrini m. (eds.) (1999) i beni geologici della 253geo-tourist map of ... provincia di modena artioli ed., modena, 104 pp. bertolani m. (1980) fiorano e il suo territorio docum. e ric. comune di fiorano modenese, pp. 1-24. biasutti r. (1907) le salse dell’appennino settentrionale mem. geogr. 2, pubbl. suppl. riv. geogr. it. carton a., cavallin a., francavilla f., mantovani f., panizza m., pellegrini g.b., tellini c., con la collaborazione di bini a., castaldini d., giorgi g., f loris b., m archetti m., s oldati m., s urian n.(1994) ricerche ambientali per l’individuazione e la valutazione dei beni geomorfologici. metodi ed esempi il quaternario, 7(1), pp. 365-372. castaldini d., chiriac c., ilies d.c. con la collaborazione di barozzini e. 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(1990) le carte geografiche libreria goliardica, pisa, 294 pp. mucchi a.m. (1966) il fenomeno delle salse e le manifestazioni del modenese atti soc. nat. mat. modena, 97, pp. -31. mucchi a.m. (1968) le salse del modenese e del reggiano. l’universo, 48 (3), pp. 421-436. panizza m. (1992) geomorfologia pitagora ed, bologna, 397 pp. p anizza m. (2001) geomorphosites: concepts, methods and examples of geomorphological survey chinese science bulletin, 46, pp. 4-6. panizza m. & piacente s. (2003) geomorfologia culturale pitagora ed., bologna, 350 pp. p antanelli d. & s anti v. (1896) l’appennnino modenese ed. cappelli, rocca san casciano, ristampa 1996, ed. iaccheri, pavullo nel frignano. papotti d. (2002) riflessioni preliminari ad una standardizzazione della simbologia per l’escursionismo bollettino dell’a.i.c., no. 114-115, pp. 55-66. pellegrini m., brazzorotto c., forti p., francavilla f. & r abbi e. (1982) idrogeologia del margine pedeappenninico emiliano-romagnolo in: g. cremonini & f. ricci lucchi (eds.), guida alla geologia del margine appenninico-padano, guida geol. reg. soc. geol. it., bologna, pp. 183-189. piacente s. & poli g. (eds.) (2003) la memoria della terra, la terra della memoria università di modena e reggio emilia regione emiliaromagna, edizioni l’inchiostroblu, bologna, 159 pp. piacente s., bertacchini m., coratza p. & malmusi s. (2000) il patrimonio geologico: nuova occasione di sviluppo turistico e culturale. un esempio in emilia-romagna atti. conv. “sviluppo economico e sostenibilità: il turismo ambientale e culturale occassione di nuova occupazione”, 2-6/11/1999, anacapri, 56-563, edizioni l’inchiostroblu, bologna, 159 pp. pieri m. & groppi g. (1981) subsurface geological structure of thepo plain, italy c.n.r., pubbl. 414 p. f. geodinamica, 13, 7, 13 pp. pliny the elder (around 50 a.d.) historia mundi 254 d. castaldini et al. naturalis book ii-85. einaudi ed., torino. poli g. (ed.)(1999) geositi. testimoni del tempo regione emilia-romagna, edizioni pendragon, 259 pp. ramazzini b. (1698) de petrolio montis zibinii modena reynard e., holzmann c., guex d. & summermatter n. (eds.) (2003) géomorphologie et tourisme act. réunion annuelle soc. suisse de géomorphologie, 21-23/9/2003, finhaut (suisse), 216 pp. servizio meteorologico regionale della regione emiliar omagna (1995) i numeri del clima ed. promodis italia, brescia, 305 pp. sestini a. (1981) cartografia generale patron ed., bologna. spallanzani l. (1795) viaggi alle due sicilie e in alcune parti dell’appennino pavia. stohr r. (1869) intorno agli strati terziari superiori di montegibbio e vicinanze atti soc. nat. mat. modena, 4. stoppani a. (1873) il bel paese milano, 651 pp. tosatti g. (2002) the mud volcanoes of salse di nirano in: p. coratza & m. marchetti (eds.), geomorphological sites: research, assessment and improvement, workshop proceedings, 19-22 june 2002, modena, pp. 95-97 wimbledon w.a.p., benton m.j., bevins r.e., black g.p., cleal c.j., cooper r.g. & may v.j. (1995) the developement of a british methodology for selection of geological sites for conservation part 1, modern geology, 20, pp. 159-210. 255geo-tourist map of ... imp.bini glacial landforms in the apuan alps (tuscanyitaly): features in danger of extinction monica bini phd student, università di bologna. research carried out at dipartimento di scienze della terra, università di pisa, email: bini@dst.unipi.it abstract: m. bini, glacial landforms in the apuan alps (tuscany italy): features in danger of extinction. (it issn 0394-3356, 2005). the remaining glacial landforms of the apuan alps are of great scientific interest, but they are not adequately exploited, and even their very conservation is in peril, despite the protective limitations imposed by the regional park of the apuan alps. from a first analysis of remaining glacial landforms, two sites in particular have been identified as being worthy of special attention, for different reasons: the arni moraine and the glacial complex of campocatino. riassunto: m. bini, forme glaciali delle alpi apuane (toscana-italia): elementi a rischio di estinzione. (it issn 0394-3356, 2005). i resti glaciali delle alpi apuane hanno un grande interesse scientifico, ma non sono adeguatamente valorizzati, e addirittura è messa in discussione anche la loro conservazione, nonostante i vincoli imposti dal parco delle alpi apuane. da una prima analisi dei resti glaciali apuani, sono emersi tra gli altri due siti che meritano per ragioni diverse una particolare attenzione: la morena di arni e il complesso glaciale di campocatino. keywords: apuan alps, glacial landforms, geomorphosites. parole chiave: alpi apuane, morfologia glaciale, geomorfositi. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 175-178 1. introduction the glacial landforms of the apuan alps, dating to the last climatic change of the pleistocene, deserve attention due to their importance in palaeogeographic reconstructions and for the study of glacial processes in the apennines. it is particularly interesting to look into the reasons governing the extension of the apuan glaciers given the altitude of the chain, no higher than 2000 m, the short distance from the sea (10-15 km) and its latitude (44°n) (fig. 1). the apuan glacial remains have very interesting characteristics. in fact, in the apuan chain there are the lowest deposits in the whole of the apennines. the reasons for this are probably to be found in the particular climatic regime of the area, above all its high rainfall, which at the high altitudes reaches 4000 mm of rain per year. this seems to have favoured the formation of glacial deposits at low altitudes. the würm period of permanent snowcover in the apuan alps has been calculated for the internal areas at around 1200-1300 m and this is the lowest recorded in the apennines chain (braschi et al., 1986). palaeogeographic reconstructions have shown that during the last glaciation, on the north eastern sides of the apuan alps there must have been at least 9 glaciers, which extended down as far as the garfagnana piedmont plain. in particular, by 1912 merciai had already identified the presence of the following 9 glaciers: those of orto di donna, gramolazzo, pisanino, campocatino, tambura, arni, altissimo, corchia and pania secca, all on the eastern side. various traces indicating small glaciers on the seaward side were also found (federici, 1981). these are mainly erosional landforms, given that high slope gradients have prevented the conservation of extensive moraine deposits. however, very little remains of the apuan glacial landforms. with time, evidence of their presence has been eliminated by fluvial-glacial or fluvial processes, by the karst processes particularly influential in the apuan area, given the lithology and rainfall regime, but also by the action of man with the centuries-old marble quarrying activities. the latter have destroyed the glacially-modelled slopes, removing both erratics and moraines. it is for this reason that the few remaining forms should be carefully safeguarded. from an initial survey on apuan glaciation, two sites in particular have been identified which deserve, for different reasons, special attention and require a clear policy of sustainable conservation. the first site is that of the arni moraine, which, despite its importance in the history of glacial studies in the apennines, is today in a serious state of degradation. the second is the glacial complex of campocatino, which, on the other hand, is well conserved, easy to interpret and particularly suitable for educational activities associated with glacial processes. 176 m. bini 2. the arni moraine the arni moraine (fig. 2) is a typical example of the degradation undergone by the apuan glacial landforms. it appears in an impressive section near the village of arni at an altitude of 920 m. the deposit reaches a height of 50 m starting from the bed of the turrite secca torent and is made up of a chaotic mass of marble pebbles with subordinate presence of also phyllites and verrucan schists. in the complex there is a well-cemented medium-to-finely grained matrix, and in some pebbles the typical glacial striations can be seen. the moraine was the first glacial deposit of the apennines to be described in 1872 simultaneously by cocchi and stoppani. the two geologists identified the moraine separately and such was the reciprocal respect between the two that neither of them claimed for himself this important discovery. in particular, stoppani described it as a: “…morena composta quasi esclusivamente da massi di bianco saccaroide, roccia che costituisce quasi per intero le montagne dell’ingiro della valle. gli scisti talcosi, talora quarziferi, che si scoprono associati ai calcari ai limiti della morena e si levano verso monte altissimo si scoprono in frantumi nel detrito morenico. alla presenza di queste rocce si deve certamente la striatura dei massi calcarei che si presentò nel modo più evidente alla estremità occidentale precisamente ove dipende dal m. altissimo”. in order to understand how important the discovery of the arni moraine was in the history of glaciation in the fig. 1 the study area at the scale of 1:65.000 (enlarged from foglio 96 –massaof carta topografica d’italia, igm). l’area di studio scala 1:65.000 ( ingrandimento del foglio 96 massa della carta topografica d’italia –igm-). apennines, it is enough to read the few lines that follow: “l’esistenza d’un ghiacciajo nella val d’arni può ritenersi come indizio sicuro dello sviluppo del terreno glaciale nelle apuane, principalmente sui versanti settentrionali e nei bacini dipendenti da montagne più alte di quelle della val d’arni. non manca pure di acquistare valore di somma probabilità d’opinione da me già espressa nel 1865 che antichi ghiacciai debbano scoprirsi nelle regioni più elevate dell’appennino centrale, principalmente nelle dipendenze del gran sasso d’italia, il quale avendo 2899 m di elevazione, supera del doppio quella del m. altissimo, che è di soli 1590.” (the presence of the arni moraine was considered by stoppani to be important evidence suggesting the existence of glaciers elsewhere in the apennine chain). cocchi, from the lunigiana area, who describes the moraine as being a little less extensive than stoppani, remarks how the deposit “…lungi dall’essere isolato è anzi frequente ripetendosi in tutte le vallate principali delle nostre pania”, in this way reinforcing the opinion of stoppani regarding the probable widespread distribution of this type of deposit in the apennines. the arni moraine is at a higher altitude compared to the other apuan moraines, probably because the glacier which generated it was the only one facing south. other small ice masses extended down from monte fiocca towards south, west and south east, whilst a larger mass, which was the largest part of the arni glacier, extended southwards from passo sella and from monte macina. along the channel of burrone at 1050 m we can see some scarce morainic detritus, but the area, as is often the case in this district, has been so disturbed by the marble quarrying that almost all the remaining deposits have been obliterated. the arni moraine remains the only deposit that is still visible and offers a particularly detailed section which can be 177glacial landforms in the ... used to illustrate the salient features of glacial and fluvio-glacial deposits and their interrelationships. the site of the section is easily accessible by car and there are very suitable facilities nearby, such as hotels, restaurants and bars. its exploitive characteristics, together with its high scientific and historical value, make it an ideal geosite. today however the moraine is in a state of serious degradation. to make things worse, close by there is an illegal dumping site and a water purification plant has recently been built in the area. despite the protection afforded by the park of the apuan alps there is no corresponding sustainable exploitation of the site. in fact, there is basically no recognition of the inherent value of the site, either in the local community or among the few tourists who visit the area. unfortunately, it is effectively an area better known for having been ruined by the quarrying activity. recovering and sustainably developing this site would mean a significant contribution to re-evaluation of the area. 3. the glacial complex of campocatino the glacial complex of campocatino (fig. 3) is of great educational interest and is an area recognised as important by the local community, and which is the destination of a certain number of tourists, also because of its location near the well-known medieval village of vagli. campocatino is a veritable jewel in the park of the apuan alps. it is a small glacier, 1 km long, which originated from the monti tombaccia and roccandagia, and extended down to a small glacial hollow with a length of 500 m and width of 250 m, creating a double circular moraine with the typical arched shape in its frontal part (paci, 1935; tongiorgi & trevisan, 1940). the two moraines, about ten metres high and 500 m long, are almost exclusively made up of marble from m. roccandagia. the matrix is scarce, particularly in the external circle, due to the limited transport of these materials. the shape is typical and the deposits, despite their small size, are easy to interpret and very well conserved. using the moraine it is possible to reconstruct, something quite rare in the apuan alps, various glacial stages or frontal oscillations of the glacier. the landscape is made even more impressive by the presence of a small pastoral village, with small stone-built alpine huts standing on the moraines and once used by the shepherds coming from the lower valley of vagli di sopra and neighbouring areas during transhumance. this human element, which reflects one of the typical activities of the apuan area, particularly in the garfagnana valley, adds a cultufig. 2 frontal view of the arni morain deposit. notice the general degrade of the area with poor potential preservation. vista frontale del deposito morenico di arni, da notare il generale degrado dell’area. 178 ral historical value to the natural resource. another anthropic element of a certain historical importance is the hermitage of st. viviano, which can be reached in only 30 minutes on foot. apart from its particular geological, geomorphological and historical-cultural features, the area is also of great interest as regards fauna and flora. in fact, there are rare and endemic species, so much so that the area has been a lipu (italian league for the protection of birds) reserve since 1991. although size is usually an important criterium in recognising the quality of a geomorphosite, in this case it is precisely the fact of being a miniature glacier which makes it possible to find a combination of erosional landforms, like the cirque in the higher part of monte roccandagia, and depositional forms which are easy to interpret and difficult to find elsewhere in a limited area. it is these factors that determine its high educational value. in the plan of the regional park of the apuan alps, the area of campocatino is rightly designated as a unique landscape which combines botanical and geomorphological features with a high historical-cultural value of a still very well conserved rural settlement. the presence of suitable tourist infrastructures makes this site particularly suitable for sustainable exploitation. however, locally there is still essentially a lack of an interpretative process and realisation of the area's intrinsic value. 4. conclusions from an initial analysis of the apuan glacial landforms we can identify two sites worth safeguarding and exploiting. one is the arni moraine, which is currently in a state of degradation and lacking in any form of interpretative initiative or sustainable development of the local landscape. the other site is the glacial complex of campocatino, which, due to its clearly interpretable forms, its state of conservation and its added ecological and historical-cultural value, is an ideal geosite. the easily accessible positions of the two sites make them particularly suitable in terms of educational and informative initiatives, without having to modify the existing physical infrastructure, therefore with a need for limited investments. it is without doubt that a suitable exploitation of these two resources would have positive knockon effects on the economy of not only the park, but also of the local communities. it could contribute to promoting sustainable tourism and a new environmental recognition which, in turn, could generate new forms of protection and respect and consequently long-term conservation of these resources. references braschi s., del freo p. & trevisan l. (1986) ricostruzione degli antichi ghiacciai sulle alpi apuane atti soc. tosc. sc. nat., mem., serie a. 93, pp. 203-219. cocchi i. (1872) del terreno glaciale delle alpi apuane boll. del r. com. geol. vol. 3 n. 7-8. federici p.r. (1981) the quaternary glaciation on the seaward side of the apuan alps riv. geogr. it., an. lxxxviii , fasc. 2. merciai g. (1912) fenomeni glaciali delle alpi apuane atti soc. tosc. sc. nat. mem. vol. 28, pp. 70-89. paci m. (1935) revisione dei terreni morenici quaternari delle alpi apuane atti soc. tosc. sc. nat., proc. verb., 44, pp. 13-30. stoppani a. (1872) sull’esistenza di un antico ghiacciaio nelle alpi apuane rendic. ist. lombardo sc. lett., 5, pp. 1-7 tongiorgi e. & trevisan l. (1940) aspetti glaciali e forestali delle alpi apuane durante l’ultima glaciazione atti soc. tosc. sc. nat. proc. verb., 49 (3), pp. 3-10. fig. 3 overview of the glacial complex of campocatino with the frontal moraine (dashed line) and the backward humid depression. vista panoramica del complesso glaciale di campocatino, con la morena frontale (linea tratteggiata) e la retrostante zona umida. m. bini imp.diolaiuti& natural assets in glacialized areas and the use of gis for the valorization of high-mountain regions guglielmina diolaiuti1,2, claudio smiraglia1,2, manuela pelfini1,2 , carlo d’agata1,2 & marco caccianiga3 1“ardito desio” earth sciences department, university of milan, via mangiagalli 34-20133 milano italy. guglielmina.diolaiuti@unimi.it 2italian glaciological committee 3université laval, québec, canada marco.caccianiga@cen.ulaval.ca abstract: g. diolaiuti et al., natural assets in glacialized areas and the use of gis for the valorization of high-mountain regions. (it issn 0394-3356, 2005). the paper presents the preliminary results obtained through an experimental project focused on the use of gis software to manage environmental data surveyed in a sample area in the high italian alps (val viola bormina, so). the processing of the data (collected from field surveys with the gps rtk technique and from aerial photogrammetry analysis) made it possible to obtain geomorphological and vegetational maps (1:10.000 scale). the environmental assets were identified in the sample area through the application of some floristic indices to the vegetational data and a national sheet for the identification and the evaluation of geosites (according to the international unesco protocol) applied to the surveyed geomorphological evidences. these assets were called “high-quality floristic and vegetational zones” in the case of the botanical assets and “geomorphological sites or geomorphosites” for the geomorphological assets. the identification of the environmental assets represents the first phase of a valorisation and tourism-promotion project regarding high mountain areas. some naturalistic educational trails were prepared for this purpose. they suggest some locations for tourists to stop and observe the main environmental features of the natural landscape (both germorphosites and high-quality floristic and vegetational zones). the trails are reported in the gis on a specific layer and the linked browser also contains logistic information (time needed to reach the trail, difficulty level, hut presence, etc.) useful for organizing the trip. an advantage of the system is that users can make queries (by using the browser and/or the links on the thematic maps) to obtain information or to make changes and variations in the trail route (for instance adding new stops in the vicinity of some of the geomorphological or botanical evidences reported on the maps, but perhaps not included along the suggested trail route). this feature makes the system flexible, serving also for school use (for preparing a school trip or taking a virtual tour of the mountain region before the real trip in the field). the distribution of this product will take place through some computer points located close to the mountain regions studied and by means of an open-source cd-rom. riassunto: g. diolaiuti et al., beni naturalistici in aree glaciali e l’uso del gis per la valorizzazione di aree di alta montagna. (it issn 0394-3356, 2005). si presentano i risultati conseguiti nell’ambito di un progetto pilota che ha visto la gestione in ambiente gis di un database georeferenziato contenente tutte le informazioni naturalistiche di un’area campione dell’alta montagna alpina italiana (val viola bormina so). l’elaborazione dei dati (sia telederivati che rilevati sul terreno attraverso campagne dedicate con l’ausilio di strumentazione gps) ha portato alla compilazione di cartografia geomorfologica e vegetazionale alla scala 1:10.000. l’applicazione di appositi indici ai dati vegetazionali e del protocollo nazionale per l’identificazione dei geositi ai dati geomorfologici ha permesso l’identificazione dei beni naturalistici presenti nell’area studiata e definiti “zone di qualità floristico-vegetazionale” per la botanica e “beni geomorfologici o geomorfositi” per la geomorfologia. l’identificazione dei beni naturalistici rappresenta la prima fase di un progetto di valorizzazione e di promozione turistica delle aree di alta montagna alpina. sono stati allestiti percorsi didattici che suggeriscono al turista frequentatore alcuni stop dai quali è possibile osservare le principali emergenze naturalistiche, i geomorfositi e le aree di qualità floristico-vegetazionali presenti. i percorsi sono inseriti nel gis in layer dedicati ed i relativi database contengono anche informazioni tecnico-pratiche (difficoltà, tempo di percorrenza) per affrontare l’itinerario. l’interattività del sistema permette, inoltre, al potenziale turista di personalizzare ed arricchire l’itinerario prescelto attingendo le informazioni dall’intero data-base naturalistico a disposizione, suggerendo un approccio didattico ed un turismo virtuale dell’area in preparazione alla vera uscita sul terreno. la divulgazione del prodotto avverrà presso opportune postazioni informatiche localizzate in prossimità delle aree studiate e attraverso cd-rom distribuiti a cura dei competenti uffici regionali. keywords: geomorphosites, high mountain environment, gis. parole chiave: beni geomorfologici, ambiente di alta montagna, gis. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 275-283 1. high-mountain natural assets: previous studies and features the idea that among “cultural assets” we have to consider man-made evidences, as well as those created by nature, is not limited to scientific spheres, for it is also a common belief (panizza, 1988). the same may be said about the knowledge, valorisation and conservation required for these kinds of assets, which can be defined as true land resources (burlando, 1997a). among natural assets, geomorphological assets are the most widespread and visible (panizza, 2001). surely they are also the simplest, most understandable and recognisable because of their actions in characterizing and determining the landscape. the interest in natural assets sensu latu (biological and non-biological ones) and particularly in the geomorphological type (geomorphosites), with efforts being made for their inventory, conservation and promotion, is a relatively recent phenomenon. after some pioneer studies (for 276 g. diolaiuti et al. example nangeroni, 1968), it was only in the 1990s that a “scientific culture in geo-conservation” (translated from panizza & piacente, 2002) saw development. more recently, following the 2nd international symposium on the conservation of geological heritage in rome (1996), many efforts and projects have contributed to the growing circulation of some initiatives such as the classification, conservation and promotion of geosites. there is now a large number of papers and other published works dealing with inventories, evaluations and methodology of conservation and promotion of italian geomorphosites (see for example panizza et al., 1983; bertacchini et al., 1999 for the apennine area; burlando, 1997b; brancucci & burlando, 1999 for liguria; barca & di gregorio, 1991 for sardinia). instead, there has been less interest in highmountain areas (indicating in this non-specific way, the zones above the tree-line, smiraglia, 2001a). this could be due to numerous factors: the more limited surface extension of these areas with respect to others located downvalley, the more difficult conditions involved in visiting high-mountain lands and consequently, the problems involved in checking data collected through indirect survey techniques, the lower influx of tourists and thus the less pressing need (from a theoretical point of view) to understand the morphogenetic systems and to conserve the geomorphosites. some inventories of geomorphosites have been conducted in the province of turin (mortara, 2001), while others have focused on glacial geomorphological sites located in upper valtellina, on their promotion (diolaiuti & smiraglia, 2001; diolaiuti et al., 2001ab; 2002) and on glaciers in lombardy (pelfini et al., 1989). there are at least two strictly connected reasons suggesting a need to dedicate more interest in highmountain geomorphosites. the first one is the need for conservation and ethic promotion resulting from the increase of the tourism in high-mountain areas. this influx has made climbing and trekking popular activities not only in the alps, but also in mountain chains outside of europe such as the himalayas and the karakoram, with the inevitable growth of the magnitude of human impact and pollution. the second reason is the rapid evolution of high-mountain geomorphosites, which could shortly (a few decades) bring about not only detectable changes in their geometric and morphological features, but also their complete extinction. these last considerations may apply for particular types of morphologies, among which alpine glaciers, which with their appeal and scenic value, determine high-mountain landscapes and which, more than other natural elements of the same morpho-climatic system, are characterised by swift dynamics in responding to climatic variations through modifications in shape and volume, and through changes in the features of the landscape. in this paper, our intention is to underscore the possibility of considering glaciers and some glacier morphologies as cultural assets, more precisely as geomorphosites, and also, to suggest a method of study that is based on scientific knowledge of this natural asset, on an understanding of the natural laws governing its evolution and on an awareness of its value for mankind. we also suggest consideration of the other natural assets present in high-mountain areas and that are strictly dependent on glacier dynamics such as the floristic and vegetational assets. these biological assets respond quickly to climatic and environmental changes and have a profound impact on the mountain landscape. moreover, this kind of asset also needs to be inventoried, conserved and promoted, for an understanding of them and knowledge about them could contribute to a complete and exhaustive picture of the history of high-mountain environments (fig. 1). fig. 1 glacier as cultural asset: a black and white version of a painting of the grindelwald glacier by joann ludwig aberli (1762). il ghiacciaio come bene culturale: una versione in bianco e nero di un dipinto del ghiacciaio di grindelwald di joann ludwig aberli (1762). it is also important to note that natural processes are particularly rapid in the alpine environment and their evolution is detectable on a human time scale. therefore, the importance of glaciers as hydrological and hydro-electrical resources, as tourist attractions, as well as the geomorphological and vegetational features observable on them and on their proglacial areas, makes high-mountain zones precious lands to be conserved and promoted. 2. high-mountain tourism: distribution and differences high-mountain alpine regions are used for both traditional economical activities (agro-pastoral type) and more recently, for leisure time activities. these latter, and particularly trekking, climbing and skiing, are not distributed in a homogeneous way in the alps. they are instead concentrated in limited areas, where some elements and features of the physical landscape constitute attraction factors for tourists or where the presence of anthropic infrastructures (hotels, huts, trails, roads and cableways) make tourism possible. the result is thus that some high-mountain areas are subjected to a heavy tourist frequentation, while other areas are less well known or not known at all, and therefore completely ignored by tourists. the issue at hand is how we can contribute to an increased awareness about these lesser known areas, which are also frequently rich in unknown or undervalued natural assets, and also increase the tourist influx there, while protecting the assets. in order to obtain a greater influx to these areas, the construction of tourist infrastructures and facilities (cableways, roads, huts and hotels) is a possibility a possibility, however, that will increase not only frequentation of these zones, but also human impact on the natural landscape. if our purpose is not merely the quantitative increment of human frequentation and we aim also to increase the quality of the tourist flow, the solution may lie in our knowledge and valorisation of these areas through surveys and inventories of the existing natural assets. the environmental assets identified and inventoried have to be proposed to potential tourists in order to encourage and prepare them for a conscious use and responsible frequentation of high-mountain areas, with the aim being sustainable tourism. a first attempt to resolve this issue was proposed by the operative unit of the university of milan through the research program “valorizzazione turistica e fruizione compatibile dello spazio naturale delle alpi lombarde”, in the national cofin-murst 40% framework “la valorizzazione turistica dello spazio fisico come via alla salvaguardia ambientale” (national leader: prof. r. terranova, local coordinator: prof. m. pelfini) and in the research program “pericolosità geomorfologica in ambiente montano in relazione alle modificazioni climatiche ed alla frequentazione turistica” in the national cofin-murst 40% framework “il clima e i rischi geomorfologici in relazione allo sviluppo turistico” (national leader: prof. m. piccazzo, local coordinator: prof. m. pelfini). the study reported here proposes some methodologies for increased knowledge and valorisation of high-mountain glacial areas that are undervalued and less or not frequented at all by summer tourists. 3. applied methods this study was carried out according to the following stages and with the adoption of the following methods: 1) identification of a sample area 2) identification of the geomorphological, vegetational and floristic features by aerial photogrammetry analysis and through field surveys, combined with the gps rtk technique for the georeferencing of data. 3) data entered into a geographical browser processed by gis software. 4) selection of the surveyed features and definition of 277natural assets in ... the “geomorphosites” (according to the international protocol for the identification and evaluation of geomorphological assets) and of the “high-quality floristic and vegetational zones” (by applying botanical indices to the data collected). 5) valorization plan for the sample area by means of tourist trails to visit the environmental assets identified. 4. sample area on the basis of the authors' previous experience and knowledge of the areas, a region in upper valtellina (lombardy alps) was selected as the sample area because of its natural and anthropic characteristics. the study area is val viola bormina (so) (fig.2). this valley is divided into two sectors. in the first one, with a ne aspect, tourists are virtually an unknown presence because of the absence of lodging facilities (hotels, huts, etc.) or roads that would allow travel at least by jeep, while paths are either inexistent or poorly marked. the nw sector is instead well known and witnesses a strong influx of summer tourists due to the presence of huts and restaurants, a trail that is easily traveled by jeep and well-marked paths. the ne sector (particularly val cantone di dosdè and val dosdè) offers a wealth of geomorphological features mainly linked to present-day glaciation and glacial and periglacial morphology, in addition to a wealth of botanical features. all of the region's glaciers are located here (with the sole exception of the cima piazzi glaciers) and though the region may not reach very high altitudes (barely approaching 3,300 m), the peaks offer a picture of a high-mountain landscape, which, owing to the glaciers, stands up to any comparison with higher regions. the aim of the project was to promote frequentation of the ne valley sector through some trails that would allow tourists to understand and to learn to appreciate the natural resources present there. therefore, our attention was focused on this valley sector untouched by tourism until now, in order to identify the natural features there, particularly those of a geomorphologicalglaciological and vegetational type, and of such importance and significance as to be classifiable as natural assets (fig. 3). fig. 2 location map. ubicazione dell’area di studio. 278 5. work stages survey methods and laboratory analyses were both used for this research. in the preliminary stage, the interpretation of aerial photographs of the study area was carried out to identify the geomorphological features and the various typologies of vegetation. this first stage was followed by field surveys performed using gps instrumentation (fig. 4) as confirmation of the results of the aerial photograph analysis and to inventory all the other evidences that were not identifiable on the aerial photographs because of their small size. all the data collected were then entered in georeferenced browsers (differing for botanical and geomorphological features and for the abiotic features also divided in different layers on the base of the different processes active: glacial, periglacial, wasting of slopes, runoff water, man made) and processed by gis software to produce thematic maps (1:10,000 scale) (figs. 5a and 5b). some floristic indices applied to the vegetational data and an international protocol for the identification and the evaluation of the geosites applied to the surveyed geomorphological evidences, made it possible to identify the environmental assets in the sample area. these latter were called “high-quality floristic and vegetational zones” in the case of the botanical assets and “geomorphological sites or geomorphosites” in the case of the geomorphological assets. floristic indices (degree of rarity, naturalness and species richness) were applied to the vegetational data and non-biotic indices (educational value, scenic appeal, scientific value, rarity and uniqueness) were used for the geomorphological data to identify which of the various evidences (both vegetational and geomorphological ones) fully qualify as natural assets because of their special characteristics (fig. 6). an increasing numerical score (scale 1-5) has been applied to quantify the value of each surveyed evidence for each considered index (both abiotic and biotic ones). the browsers allowed to analyze all the inserted values and to verify the possibility for each evidence to be considered as a natural asset. we considered natural asset only the vegetational evidences that have a value ≥ 3 for all the three considered indices or the geomorphological evidences that reach (considering the sum of all the indices) a value of 15. the survey of the natural assets was conducted with the aid of gps instrumentation in order to set up a georeferenced browser, which is indispensable for entering data in a gis. the data on natural assets that were gathered during special survey campaigns were organized in dedicated layers for the purpose of producing thematic maps (glaciological, geomorphological and vegetational maps), sectorial maps or maps derived from the overlapping of different thematic layers. emergences defined as natural assets as a result of the previous stage of analyses, were considered to be the quintessential points of the areas studied, and were thus utilized as points of attraction for tourists also interested in the scientific and cultural aspects of the areas. g. diolaiuti et al. fig. 3 natural assets in val viola: glaciers, peaks and moraines in the ne sector. beni naturali in val viola: ghiacciai, cime di montagne e morene nel settore ne. fig. 4 gps survey on dosdè est glacier. rilievo gps sul ghiacciaio di dosdè est. 279natural assets in ... fig. 5a geomorphological map of the studied area processed by gis software (all the thematic layers are showed). carta geomorfologica dell’area studiata elaborata con programmi gis (tutti i layers tematici sono visualizzati). using the data collected, hypotheses were then formulated concerning the possible valorization of the study area. more specifically, the data on natural elements entered into the browsers for the preparation of the thematic maps, were used to propose multi-theme itineraries through the valley sector (the ne one), which is not as well known, but rich in interesting elements. the objective is to promote tourism through the identification and interconnection of preferential observation points. each itinerary lies within a dedicated layer and is characterized by a linked browser, in which it is possible to find data on the characteristics that make the natural element an environmental asset, as well as 280 information on logistics for the route proposed (traveling time, degree of difficulty, distances from the main lodging or assistance facilities such as camps and huts) (fig. 7). therefore, single-theme or multi-theme itineraries are proposed to the tourist to use and gain knowledge about this high-altitude valley. special attention is given to the proglacial areas, which have undergone intensive changes in the recent period. in these regions, the recent rapid glacier recession, followed by the brief advancing phase of the 1970s and 1980s, has left relatively ample areas exposed. geomorphological evidences left by glacial activity are easily observable there, particularly the newly formed moraines (diolaiuti, 2001; rossi et al., 2003), roches moutonnées, and subglacial morphological features, where stream, periglacial and slope morphodynamics are presently predominant. geomorphological interests can be combined with botanical interests. in fact, the pioneer vegetation is colonizing larger sectors of the area, transforming them g. diolaiuti et al. fig 5b map about the vegetation quality of the studied area processed by gis software (all the thematic layers are showed). carta della qualità vegetazionale dell’area considerata elaborata con programmi gis (tutti i layers tematici sono visualizzati). into actual open-air laboratories. in addition to the preparation of thematic maps and specific tour routes, the environmental assets inventoried and entered in the gis offer users an interactive selection regarding the route to follow or the natural asset to identify and visit. so the users have the option of making queries (using the browser and/or the links on the thematic maps) to obtain information or to make changes and variations in the routes (for instance adding new stops in the vicinity of some of the geomorphological or botanical assets reported on the maps, but perhaps not included on the suggested path). this feature makes the system flexible, serving also for school use (for preparing a school trip or taking a virtual tour of the mountain region before the real trip in the field). in this manner, tourists will have the option of locating the assets in the database, taking into account scientific criteria (quantitative and descriptive data concerning the assets) and other criteria concerning logistics and recreational aspects. for the concluding stage of this research, the proposal consists of making available information on the tour routes and the related natural aspects through the creation of a webgis dedicated to the promotion of natural resource tourism in val viola. circulation of all the material in the school system is another possibility. this would allow schools that are planning trips to the area to prepare students in advance as to what they will find there, as well to offer a sort of virtual tour with the gis prior to the actual trip. on-site signs and markings of the proposed itineraries must be carried out with the intention of keeping environmental impact to an absolute minimum, taking full advantage of any pre-existing paths or tracks. in this regard, the suggestion has been made to follow the respective indications on the subject contained in a path manual published by the italian alpine club (club alpino italiano, 1999). in practical terms, a general information panel board is a possibility for the valley entrance zone. the board would serve for viewing the routes in their entirety, along with a description of the respective observation points. in cases where paths are unmarked, the routes will be marked by trail sign stakes 281natural assets in ... fig. 6 the international sheet used for the inventory of the geomorphosites surveyed in the studied area. each point of the sheet became a field in the geomorphological browsers linked to thematic layers (divided on the base of the different geomorphological processes active: glacial, periglacial, wasting of slope, runoff water , man-made) in the gis project carried out for this study. il protocollo internazionale utilizzato per il catasto dei geomorfositi rilevati nell’area di studio. ogni punto del protocollo inizia con un campo nelle tabelle geomorfologiche collegate ai layers tematici (divisi sulla base dei differenti processi geomorfologici attivi: glaciali, periglaciali, gravitativi, di scorrimento delle acque superficiali , antropiche) nel progetto gis portato avanti per lo studio. fig. 7 an example of a thematic browser linked to each layer. un esempio di tabella tematica collegata ad ogni layer. and cairns, made of natural materials characterized by low environmental impact. 6. conclusions the work presented here represents an example of the combination of research and its application. in fact, it is based on traditional methodologies adopting geomorphological and botanical analyses in high-altitude regions (identification of geomorphological and botanical evidence, along with the preparation of the relative maps). the analyses, however, are also utilized for the identification and selection of the high-mountain natural assets. the most important assets characterising the high-mountain landscape have been identified as glaciers and proglacial morphologies, with the resulting necessity to survey, inventory, evaluate and protect them. the different values (scientific, cultural, socioeconomic and scenic) of these assets make them natural resources that cannot be neglected and identifiable not only as objects of the natural landscape, but also as sensitive systems (smiraglia, 2001b) and true examples of geo-diversity. moreover, glacier action on the extension, velocity and degree of development of the vegetational distribution is underscored, for it adds further value to the high-mountain environment and can itself be defined as a natural asset. the use of the international protocol for the identification of the geomorphosites is suggested and applicable to glacier lands and morphologies. however, some changes in this protocol are also required in order to take into account the characteristics and features specific to these landforms. it is particularly important to underscore two features that augment the scientific quality of glacier environments, but also the difficulties involved in studying them. the first feature is the rapid evolution time of alpine glaciers and glacier morphologies in responding to the climatic and environmental driving factors of landscape change. the second factor is that they represent excellent keys for the study and understanding of the world's global equilibrium. regarding the fast evolution of high-mountain landscape changes, the rapidity, dimensions and dynamics of the changes in glaciers, allow the glaciers themselves to take on a representative and emblematic role in the global environmental system and in its delicate and changeable balance. glacier changes over time do not affect solely their scientific value, but also the other values of these landforms, particularly their scenic value. a good example of this last feature comes from the comparison of historical iconographies. it provides further clarification of the weight of glaciers in modelling the high-mountain landscape and their influence on human perception of the alpine environment. as for the function of glaciers in the world's environmental balance, we must stress the key role they play in all scientific research aimed at understanding the relationships between the lithosphere, hydrosphere and atmosphere, in reconstructing past climate history and in terms of their importance as sensitive climate indicators. all things considered, glaciers really can represent true environmental assets and natural resources and to repeat the words of sharp (1988), they are “unusual, intriguing elements of our natural environment..., a never-ending source of fascinating information and discovery..., in themselves beautiful and mysterious. by their actions they have helped create some of the most spectacular scenery of this earth.” in conclusion, the main aim of the project was to increase popular knowledge about high-mountain regions through the promotion of a tourism that is nondestructive and of low impact, especially with respect to areas where tourist traffic is inexistent or very limited. the application of a gis revealed to be a useful and flexible tool for this purpose and it allowed for simple management of all the natural assets surveyed. acknowledgements the authors thank anna lombardi for collecting and processing part of the field data. the research was conducted as part of project “pericolosità geomorfologica in ambiente montano in relazione alle modificazioni climatiche ed alla frequentazione turistica” in the national cofin-murst 40% framework “il clima e i rischi geomorfologici in relazione allo sviluppo turistico” (national leader: prof. m. piccazzo, local coordinator: prof. m. pelfini). references barca s. & di gregorio f. 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(2001b) ghiacciai: da oggetti del paesaggio a sistemi sensibili “ghiacciai e aree protette atti del convegno internazionale di sondrio, 1997”, sondrio, centro documentazione aree protette, pp. 113-125. 283natural assets in ... microsoft word 00_indice_bm03 available online http:/amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 25 (1), 2012, 67-74 an approach to body size fluctuations in quaternary continental mammals: the case of hippopotamuses from western europe paul p.a. mazza & adele bertini dipartimento di scienze della terra, dst, università degli studi di firenze, italy corresponding author: p.p.a. mazza <paul.mazza@unifi.it> abstract: several paleoenvironmental analyses show that community change over geological time is driven by ecological factors which, in turn, are regulated by climate. to most effectively examine the origin of community change researchers need to single out and track specific paleobiological properties and to see how much they depend on local or more general constraints. a suite of proxies have been used to analyze ecologically based community change. body size is one of the most sensitive to ecological factors and is therefore deemed to disclose significant information on past environmental conditions. bergmann’s rule proposes a thermoregulatory explanation to the latitudinal gradient of increasing animal body size. whereas some animals fit the predictions of bergmann's rule, others do not, or even correlate negatively. several critical reviews cast doubts on the “thermal” interpretation of bergmann’s rule, and proposed alternative hypotheses for geographic variation in body size based on various physiological, biological and ecological constraints. the ice age cycling that was set off by the 2.6 ma arctic ice cap expansion led gradually to ever increasing environmental patchiness, and the effects of this habitat fragmentation became particularly evident in the late pleistocene and holocene. megafaunas progressively split up into metapopulations confined into ever smaller and more isolated habitats. this led numerous large mammals to experience endemic evolution in isolation, and body sizes changed in ways similar to those observed in land mammals distributed on true islands. keywords: body size, bergman’s rule, mammals, climate change, quaternary. 1. introduction the processes that cause community change over geological time have been one of the most investigated topics in paleoecology. to most effectively examine these processes researchers need to single out and track paleobiological properties unaffected by local constraints. body size is most sensitive to ecological factors and can disclose significant information on past environmental conditions. the pattern and extent of body size change in quaternary land mammals has often been connected to climatic change (tchernov, 1968; davis, 1977, 1981; klein, 1986). quaternary is actually characterized by particularly unstable conditions, with long-term cooling trends and glacial cycles of ever increasing amplitude. there are two major, relatively abrupt climate transitions: one just before its onset, around 2.7 myr ago, of a major northern hemisphere glaciation, the other is the so-called “mid-pleistocene revolution” (mpr; berger & jansen, 1994) when the dominant periodicity of glacial response switched from 41 to 100 kyr. an equivalence can be established between the body size change of a specific taxon within a community over geological time, on the one hand, and the change of a phenotypic trait of an organism over geological time, on the other. as phenotypic changes reveal specific adaptations, so can body size changes provide information on the environmental modifications that caused them. bergmann’s rule, pros and contras many studies have highlighted the coincidence of climate or latitude change with size changes in various mammals. bergmann (1847) observed a latitudinal increase in animal body size and proposed a thermoregulatory explanation to the phenomenon. climate/latitudeinduced size change is often connected to peculiar allometric responses. in 1877 joel a. allen gave the fundamentals of what was from then on known as allen’s rule observing that land mammals from colder climates usually develop shorter limbs than their counterparts from warmer climates. subsequently re-examined and reformulated, the so-called bergmann’s rule (or mechanism sensu meiri, 2011) was found to apply also to poikilotherm vertebrates, as well as to a number of invertebrate taxa (e.g., ashton, 2002; makarieva et al., 2005, and references therein), which however are not subject to the heat-conservation mechanisms underlying bergmann’s rule. mclean (1991) believes that large mammals store more heat than smaller mammals, but cannot release it as much easily owing to their relatively small surface/volume ratios. the rapid warming at the transition to an interglacial/interstadial phase causes greater embryogenesis dysfunction in larger mammals than in smaller ones (mclean, 1991). in these periods large mammals may therefore either disappear, experience dwarfing if they are given sufficient time to adapt to the new conditions, or otherwise reduce in size before becoming extinct (kurtén, 1972; guthrie, 1984). meiri & dayan (2003) reviewed the occurrence of bergmann’s rule in statistical samples of birds and mammals, observing that over 72% of the birds and 65% of the mammals they examined conform to it. meiri et al. (2007) revised these results finding that the mean variation explained by latitude is 35% for birds and 37% for mazza p.p.a., bertini a. 68 mammals. meiri & dayan (2003) had also found that birds tend to adhere to bergmann’s rule whatever their size, while smaller mammals (<500 g) conform significantly less than larger ones. the latter observation is consistent with the conclusions drawn by mcdonald (1984), martin (1984), merilees (1984), and ashton et al. (2000), who found that large land mammals had been more sensitive to the climatic oscillations than smaller ones. meiri et al. (2004) obtained a significantly positive correlation between skull length and latitude in 50% of 44 carnivore species they examined, and a significantly negative correlation in 11% of those species. diniz-filho fig. 1 curve through estimated average weights of western european hippopotamuses, obtained from odontometric and osteometric data, as well as by using allometric scaling techniques (analysis in progress by the writers). stratigraphic scheme modified from bertini et al. (2010). body size fluctuations in quaternary hippopotamuses 69 et al. (2007) have also analyzed patterns of body size geographic variation in european carnivores. rodríguez et al. (2006) observed nonlinear relationships between body size and temperature, finding a strong association in northern europe, and virtually none in the south. kurtén (1968) and huston & wolverton (2011) propose the idea that mammal size is primarily connected with the amount and nature of food resources. barnosky (2005) actually showed that most body-size reductions at the last glacial/interglacial transition were ecophenotypic rather than genotypic changes. teplitsky et al. (2008) reached similar conclusions. in the light of these results, many authors have cast doubt on the “thermal” interpretation of bergmann’s rule, finding that body size is controlled by many other factors rather than just temperature. some authors advocate various physiological, biological and ecological constraints [(1) vascular control and fur insulation (scholander 1955; steudel et al., 1994); (2) food availability (huston & wolverton, 2011); (3) basal metabolic rate (steudel et al., 1994); (4) energy costs (thompson, 1942); (5) size and nature of food (teplitsky et al., 2008); (6) dominance in a community (hansson & jaarola, 1989); (7) competition (simberloff & boecklen, 1981); (8) mating success (lande & arnold, 1983)]. others suggest additional climatic factors, such as moisture levels, demonstrating that small body size is associated with hot and humid conditions while larger size is connected to cooler and drier circumstances (rosenzweig, 1968; james, 1970). yom-tov & nix (1986) and yom-tov & geffen (2006) observed that body size correlates with moisture and precipitation, and thus with primary production, better than with temperature. blois & hadly (2009) linked body sizes to climatechange-related responses of vegetation and primary productivity. during the last decade, a wealth of studies analyzed the empirical validity of ecogeographic rules (blackburn & gaston, 1998; blackburn et al., 1999; angilletta & dunham, 2003; cruz et al., 2005; millien et species and specimens ortona colle lepre valdarno colle curti untermaßfeld h. gr. h. antiquus (= h. tiberinus) incarcal i h. amphibius (barrington included) upper m2 (janis, 1990) length x breadth (cm) 28.75 30.66 log 1.46 1.48 min length x breadth (cm) 22.56 25.3 23.04 18.49 log 1.35 1.4 1.36 1.26 max length x breadth (cm) 30.24 30.36 34.16 32.48 lower m2 (janis, 1990) length (cm) 5,48 log 0.74 6.32 min length (cm) 5 6.6 5.2 0.8 log 0.7 0.82 0.71 max length (cm) 6.4 7 5.9 log 0.8 0.84 0.77 femur (allometric scaling: schmidtnielsen, 1984; reitz and quitmyer, 1988; prange et al., 1979) dc (cm) 9.5 11.7 log 0.98 1.07 dc min (cm) 9.5 9.5 8.7 7.4 log 0.98 0.98 0.94 0.87 dc max (cm) 10.8 10.2 9.3 8.6 log 1.03 1.01 0.97 0.93 fifth metatarsal (allometric scaling: schmidt-nielsen, 1984; reitz and quitmyer, 1988; prange et al., 1979) length (cm) 9.92 9.3 log 0.99 0.97 min length (cm) 9.5 10 9.9 10.3 log 0.98 1.00 0.99 1.01 max length (cm) 11 10.7 10.8 10.9 log 1.04 1.03 1.03 1.04 estimated weights (kg) 10002100 2200 2100-2750 21002600 2200-3200 1700-2750 2000 1260-3000 tab. 1 body weight estimates mazza p.p.a., bertini a. 70 al., 2006; rodríguez et al., 2006, 2007; gaston et al., 2007; meiri & gavin, 2007; meiri et al., 2007; aragón et al., 2010; gardner et al., 2011). many of these factors suggested as alternatives to bergmann’s rule could be more or less directly correlated, or at least influenced, by the environmental and climatic changes that occurred over the last 2 million years. quaternary climate instability caused changes in the vegetation (e.g., lang, 1994; bertini, 2003, 2010; tzedakis, 2003, 2007; gonzález-sampériz et al., 2010; rodriguez-sanchez et al., 2010; joannin et al., 2011; magri & palombo, 2012), as well as the progressive fragmentation of the ecosystems, with consequences on the fauna that are described further on. 2. body size change in quaternary hippopotamuses: a western european example in western europe, the significant changes in temperature and precipitation ensuing from the maximum expansion of the arctic ice cap that set off the ice age cycling caused the progressive demise of tropical and subtropical forest taxa, while altitudinal arboreal taxa and herbs spread, with the creation of new competition patterns (e.g., suc et al., 1995; bertini, 2010, bertini et al., 2010; fig. 1). vegetational modifications clearly reflect substantial paleoecological and paleoclimatic reorganizations. most commonly, but not exclusively (e.g., bertini, 2010), artemisia and ephedra-dominated open vegetation alternated with interglacial forests characterized by deciduous taxa, such as quercus, carya, carpinus, pterocarya, ulmus and zelkova in response to the early pleistocene 41 kyr climatic cycling. a ca. 100 kyr (eccentricity) cycling, which started since the transition to the middle pleistocene, intensified the glacial phenomena, but also seasonality and aridity. this had disrupting consequences on both flora and fauna. many resident animal taxa became extinct, whereas others were replaced by new incomers from eastern europe, central asia, and africa. some of the western european inhabitants seem to have changed size in coincidence with climatic variations. hippopotamuses might represent a good example (fig.1). if the body sizes of european quaternary hippopotamus are estimated from stratigraphically controlled remains, it seems that these pachyderms grew smaller from the jaramillo subchron onwards (table 1). during the second half of the middle pleistocene these suiforms turned progressively rarer, especially during the coldest phases of this interval (mis 8, 6). at the beginning of the late pleistocene, during the very warm mis 5e, large to very large hippopotamuses dispersed as far north as the british isles. it is worth noting that western european hippopotamuses grew smaller in coincidence with the mpr (~1.2÷0.5 ma) and just after the disappearance of the subtropical vegetal ecosystems from the mediterranean area, around 1.2 ma (e.g. combourieu-nebout & vergnaud-grazzini, 1991; bertini, 2010). the great modifications in the structure and composition of vegetal formations induced by the long lasting glacial phases (up to 85 ka) and short interglacial phases (up to 15 ka) of this time period had significant consequences on the type and availability of food for the fauna. in a working hypothesis in preparation by the writers, hippopotamuses turned smaller under the prevalently cooler middle pleistocene conditions, in contrast to bergmann’s predicted pattern, as an indirect response to climatic change, owing to the unsteadiness in food availability. this would fully agree with kurtén’s (1968) and huston & wolverton’s (2011) idea that mammal size is primarily connected with the amount and nature of food resources. 3. the “insularization” of quaternary continental mammals the mpr caused increasing habitat fragmentation (simakova, 2001; markova et al., 2001; zazula et al., 2003), whose effects became particularly evident in the late pleistocene and holocene. the mosaic evolution of plant communities, as habitats grew smaller and more isolated, turning into habitat islands (lister & bahn, 1994; ward, 1997; reumer, 2007), affected the evolutionnary relationships between herbivores and the vegetation (graham & lundelius, 1984). megafaunas progressively broke down into metapopulations. as interbreeding became ever more infrequent, subpopulations were increasingly exposed to the effects of inbreeding, genetic drift as well as morphological change. when the intensity of interbreeding turned excessively low, evolutionary change tended to resemble that of insular settings (schmidt & jensen, 2003). numerous mammals grew smaller (e.g., edentates, mastodonts, wild boar, gazelle, goat, aurochs, bison, deer, fox, wildcat, spotted hyena, beech marten, burrowing mole rat, hedgehog, porcupine: kurtén, 1965; tchernov, 1968; frenkel, 1970; heller, 1970; mcdonald, 1981; king & saunders, 1984; martin, 1993; martin & barnosky 1993; wilson, 1996; barnosky et al., 2003; blackburn & hawkins, 2004, rodríguez et al., 2006, cooper & purvis, 2010; saunders et al., 2010), with results somewhat fitting the predictions of the so-called island rule (foster, 1964; sondaar, 1977). insular populations, both in true and ecological islands, are in fact under the control of strict genetic and ecological constraints (lomolino et al., 2010). as in true islands, in isolated ecosystems population densities are bracketed between a maximum number of individuals, determined by the carrying capacity of the environment, and a critical minimum number of individuals to prevent extinction. largesized animals seems to be left with no other choice but to decrease their size to lower selective pressure in insular isolation. 4. conclusions because mammal body size is most sensitive to ecological factors, size changes are often considered as a useful proxy indicator to monitor climatic changes, not only in the past. in fact, declining body size has recently been considered the third universal response to climate, together with changes in phenology and distribution of species (gardner et al., 2011). in his pioneer contribution bergmann (1847) stirred debate over the relation between temperature and body size. the controversy peaked over the years, with convinced supporters and opponents both with shrill and convincing arguments on the merits or shortcomings of bergmann’s rule. many body size fluctuations in quaternary hippopotamuses 71 studies have admirably shown that mammalian body size is governed by, and responds to, a number of factors, which include temperature, precipitation and moisture, physiologic constraints, basal metabolic rate and energy costs, environmental carrying capacity (food availability), degrees of environmental stability, interspecific competition, predator-prey interaction, just to mention some. a body size that is thought to be diagnostic of a particular environmental situation may actually arise for different reasons, being the result of the interplay of an array of factors which may be, to various degrees, interdependent. researchers involved with these issues are therefore confronted with a tangled network of related variables, which imposes to inquire each instance individually, on a case-by-case basis: model (“rule”) generalization is not easy to achieve. today, researchers could have the unprecedented opportunity to test the effects of global warming on fast-reproducing animals (e.g., gardner et al., 2011). paleoclimatological analysis and oxygen isotope curves clearly show that, with the outstanding exceptions of particularly warm episodes (e.g., mis 47, 37, 11, 9, 5e), earth’s climate has been progressively deteriorating over time, trending towards increasingly cooler and somewhat drier conditions. the escalating environmental patchiness during the quaternary translated into habitat fragmentation, and this in turn caused the splitting up of populations into subpopulations or metapopulations. owing to this parcelling of habitats and biotas, body size has been ever more under the influence of factors (e.g., food availability) that may not always operate or be accessible latitudinally, but rather areally, in accordance with the habitat specificity of the species (meiri et al., 2007). countless studies show that mammal body size change is a most effective sign of some ecological change, of whatever kind and degree (aragon et al., 2010). and possibly even a predictor of environmental instability. deepening our knowledge and understanding of this phenomenon can therefore be a promising direction for future research aimed at environmental monitoring. acknowledgements we thank e. russo-ermolli and one anonymous reviewer for useful suggestions which improved this paper. this study was funded by ex 60%miur (ministry of education, university and research) grants to p. mazza and a. bertini. references allen j.a. 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(2003) ice-age steppe vegetation in east beringia. nature, 423, 603. ms. received: january 20, 2012 final text received: march 13, 2012 imp.cucchi& geology and geomorphology of the “rosandra” valley for a cultural enhancement franco cucchi, alessio mereu, sara oberti, chiara piano, anna rossi & luca zini department of geological, environmental and marine sciences, university of trieste; cucchi@units.it abstract: f. cucchi et al., geology and geomorphology of the “rosandra” valley for a cultural enhancement. (it issn 0394-3356, 2005). the rosandra valley is located near trieste (italy), on the border of classical karst, and is a canyon-like depression excavated in tertiary limestone. the origin of the valley is mainly due to presence of faults and overthrusts and different attitude to erosion between limestone and marls, which makes it a beautiful example of lithological and structural control on morphogenesis. furthermore, its slopes are interested by extended and mature underground karst phenomena that contribute to making the whole hydro-structure more interesting. the valley is also remarkable for its local vegetation, due to its particular climatic conditions, and to its prehistoric and historical value, stemming from its geographic location. riassunto: f. cucchi et al., geologia e geomorfologia della val rosandra per una sua valorizzazione culturale. (it issn 0394-3356, 2005). la val rosandra è ubicata in provincia di trieste, al confine del carso classico, ed è una valle profondamente incisa in calcari terziari. la sua origine è principalmente legata alla presenza di faglie e di sovrascorrimenti ed all’erosione selettiva dovuta alla presenza di litotipi diversi come calcari e marne; tutto ciò ha creato un esempio spettacolare di forme influenzate dalla litologia e dalla tettonica. inoltre i suoi rilievi sono interessati da estesi e maturi fenomeni carsici ipogei così da creare una singolare idrostruttura. la valle è anche attraente per la vegetazione locale, condizionata dalle particolari condizioni climatiche, e per l'interesse preistorico e storico dovuto alla posizione geografica. key words: rosandra valley, karst, geomorphology, geology, geopark. parole chiave: val rosandra, carso, geomorfologia, geologia, geopark. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 185-196 1. introduction "the valley" – as the triestines call it – opens onto the western side of the trieste classical karst plateau: it is constituted by the intermediate and the final stretch of a creek – the rosandra creek – that originates from the confluence of two water streams – the t. botazzo and the rio griza – whose springs are located in slovenia, a few miles away from the italian border. the initial stretch, now in the slovenian territory, consists of a normal wide verdant valley that, at one point, deeply engraves white bare limestone rocks. after some miles, it results in a plain overlooking the gulf of trieste. the whole area, and in particular m.te stena on the right, is characterised by surface and underground karst. 100 cavities have been surveyed, some of which cover many hundred metres. among them one of the most beautiful cave can be found (the gualtiero savi cave, point 1, fig. 2): it has rich speleothemes (no important concretions dating back to later than 300,000 years ago have been found), an interesting morphology of corrosive and sedimentary origin, and extends over approximately 4,000 metres, thus testifying to the complex geomorphologic and hydrogeological evolution of the “classical karst”. fig. 1 location map. ubicazione. 186 f. cucchi et al. on the left side, the valley was delimited by the so-called “via del sale” (“salt road”), used in roman times and in the middle ages to transport salt to the inland villages. the tracks of the first railway line connecting the hapsburg port of maria theresa to vienna and ljubljana (1887), have now been converted into a cycle track, which means that the old path is still used nowadays (point 3, fig. 2). caves with prehistoric remains, ruins of castles and hill forts, mills, country churches, ruins of the roman aqueduct and abandoned querries prove the intense and ancient settlements in the area (fig. 2). the valley’s peculiar climatic and geomorphologic conditions (closeness to the sea, swift passage from the sea level to an altitude of over 400 metres) and its geographical location (the farthest northern limit of the adriatic sea still belonging to the european continent) provide the valley with utterly peculiar fauna and vegetation. the valley, which has been long regarded as “special” for its outstanding naturalistic value, also presents an important and unique geological and geomorphologic heritage and is worth becoming an interesting geopark. 2. geological considerations as far as the lithostratigraphic succession is concerned, the following items can be found (going from the most ancient to the most recent one): the limestone rocks of the “opicina member” (thanetian-llerdian), belonging to the informal “limestone formation of trieste karst” (cucchi et al., 1989a), the “fucoidi” marls (lower eocene), the flysch (lower and medium eocene) and quaternary deposits. as can be observed from the viewpoint of s. lorenzo (point 4, fig. 2), the most abundant and characterising lithotype is the “opicina member” limestone. it includes compact limestones, usually of light grey but also of black colour, fetid when struck, presenting highly fossiliferous migrated oils (foraminifers, among which alveolinids and nummulites, gastropods ed echinoids) sometimes spathized with fracturing from scalelike to pseudo-conchoidal. limestone stratification is usually sharp and on a decimetre scale but metre-thick limestone banks with indistinct stratification are not infrequent. consequently, karstifiability ranges from high to very high and erodibility from low to very low. according to recent studies (drobne, 2003, in press), the above-mentioned limestones were deposited in an “intermediate photic zone” environment (hottinger, 1997), i.e. with bathymetries ranging between 40 and 80 metres. these limestones mainly testify to coastal marine settings. marly limestones characterize the upper-most part of the member, showing an increasing occurrence of planktonic foraminifers. these limestones indicate an increasing depth and the decline of previous taxa, prior to the drowning of the carbonate platform in relation to terrigenous turbidites (flysch). at the top, the increase in terrigenous materials progressively modifies the lithology, to reach facies of grey and hazel marl-limestone with decimetre-scale thickness (cucchi et al., 1989b), thus testifying both to the carbonate platform drowning and to a sharp change in regional paleogeographical conditions. from a stratigraphic point of view, eocene “fucoidi” marls follow: they are basically lamellar argillites whose colour varies from grey to bluish (fig. 3). they reach their maximum 10-metre thickness on m.te stena hillsides along the cycle-track built on the ancient train tracks (point 5, fig. 2). if thickness is definitely modest, remarkable instead are geomorphologic conditionings: due to its plasticity, the horizon is often characterised by lowangle reverse faults, in acts as non-kastifiable level, is impermeable and shows rather high erodibility. at a higher-contact level, the flysch that outcrops is constituted by alternation of marl levels and sandstones with variable thickness. marl thickness ranges from millimetreto centimetre-scale; sandstone thickness from centimetreto decimetre-, sometimes metrescale. sandstones, which are usually predominant, are moderately sorted, with average grain size being approximately 0.1 mm. as they are carbonate-cement quartzo-feldspathic sandstones, they can be defined graywackes. on average, they are composed by minimum 50% silicon oxide (containing 43÷53% quartz and 6÷11% flint) and by feldspars (18÷26%), mainly plagioclase and mica feldspars (4÷6%) with chlorite and muscovite predominating over biotite, carbonates (16÷20%, both cement and often highly altered clasts), and a series of other minerals present in minimum quantities (iron oxides, glauconite, tourmaline, garnets, zircon, rutile: cumulative percentage between 1 and 3%). these mineral constituents are practically sterile, even though some jellyfish rests have been found, alongside rare globigerinae. marls, whose mineral composition is fairly similar to that of graywackes, but for a higher percentage of carbonates than of other mineral constituents, are not very rich in organic residues. the most abundant organic elements are plankton foraminiferans such as globigerinae and globorotaliae. the fossiliferous fraction of basal marls dates back to the middle-high cuisian age (onofri, 1982). this alternation confirms the progressive platform drowning and the appearance in the basin of elements deriving from the alpine orogenesis in european and balkan regions. sedimentary structures such as flutes and burrow casts are frequent. due to its plasticity, flysch presents low-range folds giving it a good level of erodibility, plasticity and substantial impermeability. quaternary deposits are constituted by sometimes-cemented scree slope, by alluvial deposits and by eluvial-colluvial coverings. in the case of slope debris, clasts are elements mainly of limestone nature, belonging to the opicina member: they are sharp-edged and vary in size. only rarely do sandstone clasts, whose shape is more rounded, appear; in the breccias, the cement is calcitic and of reddish-grey colour. its cementation level highly varies from point to point and it sometimes affects the surface layers only: consequently, also permeability and erodibility can vary. some landslide displaced materials are present: they are generated by collapse and rolling of large breccia blocks slid due to undermining to the foot of 187geology and geomorphology ... f ig . 2 l o c a ti o n o n t h re e -d im e n si o n a l m o d e l o f v a l r o sa n d ra p e c u lia ri ti e s: 1 – g u a lt ie ro s a vi c a ve ; 2 o rs i c a ve ; 3 o ld a u st ri a n r a ilw a y lin e , n o w c o n ve rt e d i n to a c yc lin g t ra c k; 4 v ie w p o in t n e a r s . l o re n zo ; 5 “ f u c o id i” m a rl o u tc ro p ; 6 p re m u d a m o u n ta in s h e lt e r; 7 t e c to n ic l im it ; 8 a n tr o d i b a g n o li sp ri n g ; 9 w a te rf a ll; 1 0 s . m a ri a i n s ia ri is c h u rc h ; 1 1 š tu rk sp ri n g ; 1 2 a n tr o d e lle n in fe ; 1 3 o p p ia s p ri n g ; 1 4 v ie w p o in t n e a r m o c c ò ; 1 5 m a rt in a c u c c h i c a ve ; 1 6 g a lle ri e c a ve ; 1 7 f e ss u ra d e l v e n to c a ve ; 1 8 m .t e c a rs o h ill fo rt ; 1 9 m .t e s . m ic h e le h ill fo rt ; 2 0 r o m a n a q u e d u c t; 2 1 s a lt r o a d ; 2 2 d ra g a c a st le . u b ic az io n e s u m o d e llo t ri d im e n si o n al e d e lle p e c u lia ri tà d e lla v al r o sa n d ra : 1 g ro tt a g u al ti e ro s av i; 2 c av e rn a d e g li o rs i; 3 t ra c c ia to v e c c h ia f e rr o vi a au st ri ac a, o ra p is ta c ic la b ile ; 4 v e d e tt a d i s . l o re n zo ; 5 m ar n e a f u c o id i; 6 r ifu g io p re m u d a; 7 c o n ta tt o t e tt o n ic o ; 8 a n tr o d i b ag n o li; 9 c as c at a; 1 0 c h ie sa d i s . m ar ia i n s ia ri is ; 1 1 f o n te š tu rk ; 1 2 a n tr o d e lle n in fe ; 1 3 f o n te o p p ia ; 1 4 v e d e tt a d i m o c c ò ; 1 5 g ro tt a m ar ti n a c u c c h i; 1 6 g ro tt a d e lle g al le ri e ; 1 7 f e ss u ra d e l v e n to ; 1 8 c as te lli e re d e l m .t e c ar so ; 1 9 c as te lli e re d e l m .t e s . m ic h e le ; 2 0 a c q u e d o tt o r o m an o ; 2 1 v ia d e l s al e ; 2 2 c as te llo d i d ra g a s . e lia . 188 the side cemented on the surface, and by planar sliding on stratum levels of sometimes-thick and wide limestone banks. the alluvial deposits present along the rosandra torrent are polygenic alluviums, with scarce fine-grained fraction, locally interbedded with sandy or sandysilt lenses. pebble size – pebbles are often rounded in shape and of mainly arenaceous and secondly calcareous nature (calcitic speleothems also) – varies from centimetreto decimetre scale. a coarse diversely interbedded polygenic-alluvium escarpment, located opposite the “rifugio premuda”, bears witness to phases of intense transport (point 6, fig. 2). the eluvial-colluvial coverings are generally silty and clayey, mostly deriving from degradation of sandymarly formations and, limitedly, of carbonate formations. this red clayey soils, rich in iron oxides and known under the name of “red soils”, constitute a thin and discontinuous veil on the karst surface. from a structural point of view, the rosandra valley is part of the “imbricate structure of čič arija”, characterised by thrust wedges in a sequence of reverse faults and overthrusts that follow the dinaric trend (placer, 1981). an excellent panoramic view onto the tectonic structure of the area can be enjoyed from the viewpoint of s. lorenzo (point 4, fig. 2), located at 377 metres above sea level in proximity of the village of the same name. if we assume a geological section oriented n-s, from here the monocline imbricate structure can be observed (m.te stena on the orographic right of the creek): it first follows an apparently synclinal trend, along the axis where the valley has formed, and a clearly anticlinal trend afterwards, thus conditioning m.te carso hillsides (on the orographic left of the creek). the compression stresses coming from the north-eastern sector gave rise to three main overthrusts among the rigid limestone masses and the plastic flysch deposits (fig. 4): the reverse-fault set located on the orographic right of the rosandra creek, on the hillsides of m.te stena; the overthrust known as the “crinale fault” (ridge fault); the “m.te carso overthrust”, lowangle fault stretching towards s-e and originating the tectonically imbricate structure of the cicarija region (slovenia and croatia). the first is a case of a small overthrust family generally connecting palaeocene-eocene limestones on “fucoidi” marls of eocene age. degradation and fracturing (ranging from millimetre to centimetre scale) of the latter lithotype makes this tectonic contact along the route from the viewpoint of s. lorenzo to the village of s. antonio in bosco (point 7, fig. 2) particularly evident. here it is also possible to find flysch sandstones enclosed in the underlying marls. the “crinale fault” and the “m.te carso overthruf. cucchi et al. fig. 3 “fucoidi” marl outcrop. affioramento di marna a fucoidi. fig. 4 lithological and structural scheme: 1reverse thrusts; 2crinale fault; 3m.te carso overthrust; 4m.te carso fault. lithology: light grey = limestone; dark grey = fucoidi marl and flysch. schema litologico strutturale: 1faglie inverse; 2faglia del crinale; 3sovrascorrimento del m.te carso; 4faglia del m.te carso. litologie: grigio chiaro = calcari; grigio scuro = marne a fucoidi e flysch. 189 st”, both advancing towards wsw, identify three welloutlined structural areas. the first block, the main one, is constituted by the lithoid mass underthrusted in the “m.te carso overthrust”. this block presents numerous deformation structures due to hanging walls, many of which are brilliant study cases, such as the hook-pattern of marls and sandstones in vertical contact with the limestones, as the case that is clearly visible in the antro di bagnoli spring (point 8, fig. 2). the second block is constituted by a thrust wedge located between the “m.te carso overthrust” and the “crinale fault”. its main features can be found in two distinct sub-areas: the northern one, mostly characterised by generally reverse faults and corresponding with m.te carso culmination, where the hinge of “m.te carso anticline” has been preserved (martinis, 1971), stopping at another fault located sw – called “m.te carso fault” – oriented sw and with dip direction e, thus identifying the southern sub-area (fig. 4). the third block is delimited by the “crinale fault”, structure with axis nw-se, whose top shows a high level of limestone-rock tectonisation. to summarize, the area is characterised by rigid limestone masses that are either overthrusted, or raised on reverse faults on flysch and on plastic marl rocks, with ne dip-direction fault surface, an aspect that is clearly visible from the numerous panoramic viewpoints the valley is rich in. 3. geomorphological considerations the rosandra valley is a rare example of karst river valley with surface hydrology. the rosandra creek originates from the confluence (occurring in the slovenian territory) of two water streams – the t. botazzo and the rio griza – whose springs are located in slovenia, a few miles away from the italian border. its basin extends over approximately 21 km2, of which 8 upstream of the confluence, 6 from the point of confluence to the plain. its main course extends over 13 km from the sources to the sea, 5.5 before the confluence and 4 between the point of confluence and the access to the plain. along their course, they first erode the flysch silicon-clastic sediments; only afterwards, in proximity of the village of draga s. elia, do they erode the limestones of the opicina member and, finally, the flysch marlsandstone alternations (potleca, 1997). the first stretch erodes a relatively erodible formation, substantially impermeable. its structure presents a wide undulating syncline with upstream dip direction, in whose core the confluence between t. bottazzo and rio griza occurs. downstream of the village of botazzo, near the state border, the passage from turbidites to marls and to the underlying limestones is made apparent by an over 30-metre-high picturesque waterfall (point 9, fig. 2) that constitutes the mouth of the valley. the hillsides become steeper (with wide berms on the right and structural hillside on the left), the creek flows on the rocks, the first seepage phenomena occur and we can see the formation of a deep canyon-like depression of karst origins into the rock, rich in rapids, pot-holes, small waterfalls, enclosed meanders and basins (fig. 5). geology and geomorphology ... fig. 5 enclosed meandering. meandri incassati. 190 on the left, the creek is occasionally fed by a tributary flowing along a reverse fault that borders the north side of the m.te carso anticline. the riverbed is subject to constant diversions along the main discontinuity-set families up to bagnoli della rosandra, where the slopes decrease and the torrent flows on its ancient alluvial deposits until it reaches its mouth into the sea beyond the zaule plain. noteworthy is again the ancient and massive landslide displaced material due to planar sliding over which the small country church of s. maria in siariis rests (point 10, fig. 2; fig. 6). on the right, scattered in the woods, massive breccia blocks can be seen: they testify to the undermining process at the basis of the scree slope, cemented in proximity of the river’s sharp bend towards sw before reaching the village of bagnoli, and conditioned by the local tectonics – if not neo-tectonics – and by a paleolandslide. a system of springs contribute to feeding the torrent: the zroček spring, on the slovenian territory, the šturk spring (point 11, fig. 2), nearby botazzo village, the zaniér spring (point 12, fig. 2), flowing from the antro delle ninfe, the oppia spring (point 13, fig. 2) located by the overthrust of the “crinale” (ridge) and the antro di bagnoli spring (point 8, fig. 2) in proximity of the village of bagnoli della rosandra. the viewpoints of moccò (point 14, fig. 2) and s. lorenzo (point 4, fig. 2) offer a privileged view on the slopes overlooking the rosandra creek. these slopes are all characterised by rocky cliffs, overhanging rocks, aiguilles and mighty scree slopes, expressing a faceted lithology and complex tectonics. the “grize”, karst gravel areas, are the hallmark of the top of the mountains, alongside the rare rocky outcrop and a poor and scarcely developed soil. the small landforms caused by superficial corrosion are widely extended over the whole limestone area, characterised by medium to medium-high “karstifiability”, and particularly on monte carso hillsides, where the outcrop of limestone banks is more continuous and extended, and originates massive solution runnels (rinnenkarren). underground phenomena are equally developed: 100 caves have been discovered so far, and some of them belong to the some of the most widely extended trieste karst systems. m.te stena, in particular, hosts a comprehensive net of articulated and diversely shaped cavities, basically organised on four levels, which stretches totally over 7,000 metres, thus bearing testimony to ancient geological and hydro-geological origins. the best-known cave is the gualtiero savi cave (point 1, fig. 2; fig. 8), which covers an area of almost 4,000 metres and is the widest underground system in the rosandra valley, thus being the second cave for extension in the whole italian sector of the classical karst. it is a series of sub-horizontal galleries, structural gullies and large chambers located at 350 metres above sea level, and of a set of meanders, smaller caves and smaller galleries to be found at a lower level, approximately 50 metres above sea level (cucchi et al., 1998). surveys conducted via air-tracing methodology have ascertained that the gualtiero savi cave is connected to other cavities such as the martina cucchi cave (point 15, fig. 2), the gallerie cave (point 16, fig. 2), the fessura del vento cave (point 17, fig. 2), and numerous minor ones, whose entrances open at different levels on the hillsides of m.te stena. this is one of the most complex and interesting karst drainage systems of the “classical karst”, thus being a privileged observation point on the spelological development not only of the rosandra valley, but also of the entire karst region. caves present highly remarkable chemical and physical fillings. among them, the polygenetic conglomerates that often obliterate galleries can be mentioned; they also bear witness to intense transportation phases along water streams originating from flyschfacies basins present to the east (clasts, mainly of marly and arenaceous origin, frequently present fragments of speleothems). also speleothems are very interesting: some of them are now practically fossilized and date back to over 300,000 years ago but numerous active specimens – through which it is possible to trace recent climate changes – still exist. it should also be noted that on the left side of the rosandra creek we can find the orsi cave (point 2, fig. 2), a fossil gallery whose filling deposits are still covered by concretioned prehistoric animal remains (ursus spelaeus, rosenmuller & hinroth) dating back to at least 120,000 years ago. f. cucchi et al. fig. 6 the paleo-landslide with the church of s. maria in siariis on the orographic right of the rosandra creek. la paleofrana con la chiesa di s. maria in siariis in sinistra orografica del torrente rosandra. 4. climate considerations karst climatic conditions are peculiar due to its geographic position. karst has, in fact, a transition climate between the atlantic and the continental regime. a similar transition exists between the mediterranean and the alpine climate. as happens in all areas characterised by contact between different climatic regimes, here too local topographic influences acquire the utmost intensity (microclimate), thus contributing to the plant landscape diversification. the rosandra valley is a clear example of this phenomenon, as it features particular microclimate and plant conditions. the upper part of the valley (from klanec, 415 metres above sea level, to bottazzo, 186 metres above sea level) has a prevailing continental climate, both due to its altitude and to the distance from the sea. it is marginally exposed to the “bora” wind, and is mostly covered by trees. two hill slopes with different morphological characteristics form the lower part of the valley (from bottazzo to bagnoli, 72 metres above sea level): they have, in fact, different exposure to the “bora” wind and to solar radiation, which leads to a still higher microclimate diversification. the windward left hill slope (sw) is cha191geology and geomorphology ... fig. 7 evolution study of the rosandra valley (taken from cucchi et al., 1998) highlighting selective corrosion and karstification conditioned by lithology, tectonic structures and general geomorphologic evolution. b: beginning of the speleogenesis, conditioned by fault and stratum planes. c: development and expansion of the g. savi cave and of the gallerie cave, while the underlying fessura del vento cave starts to form. the valley deepens and the “solco del vallone” starts to form on the left of the torrent d: current situation with the high-level cavities visible. the karst now evolves with prevalent diffused sub-vertical percolation due to the wideness of the limestone surfaces exposed to atmospheric agents. schizzo evolutivo della val rosandra (tratto da cucchi et al., 1998) con erosione selettiva e carsificazione condizionate da litologia, lineamenti tettonici ed evoluzione geomorfologica e paleo-ambientale generale. in b, si ha l’inizio della speleogenesi guidata da piani di strato e di faglia. in c, la grotta g. savi e la grotta delle gallerie si sviluppano e si ampliano mentre inizia a formarsi la sottostante fessura del vento. la valle si approfondisce e si imposta il “solco del vallone” sul fianco del m. carso in sinistra del torrente. in d, si ha la situazione attuale con le cavità pensili e con prevalente percolazione ipogea subverticale diffusa data l’ampiezza delle superfici calcaree esposte agli agenti atmosferici. fig. 8 enchanting concretions in the gualtiero savi cave (photograph by umberto tognolli, taken from la grotta dei sogni, rafvg & cai). incantevoli concrezioni nella grotta gualtiero savi (foto di umberto tognolli, tratta da: la grotta dei sogni, rafvg & cai). racterised by a brief period of direct insolation; it has a particularly rigid continental climate, due to its limited altitude, with a consequent delay of the beginning of spring and earlier start of winter. the right hill slope (ne) is made up of series of vertical walls, is always leeward and exposed to the sun and, during most of the day, it is characterised by mediterranean climate conditions. when it is not lashed by the wind, the rock heats up, to the point that the air can reach maximum temperatures of 40°c in summer and of 30°c in winter. the temperature difference between the two hill slopes can reach 10°c. 5. considerations on vegetation the rosandra valley is characterised by different types of vegetation, due to the interaction between diverse environmental factors (geomorphology, lithology, microclimates) and flora: scree vegetation, karst heath, steppe vegetation, karst scrub forest, karst wood, riparian vegetation and pinewood. the vegetation that prevails in the rosandra valley is referred to as the north-adriatic “dripeto” (rich in drypetes plants), from the presence of drypis spinosa ssp. jacquiniana, which forms large pulvini scattered on the scree slope. this cenosis is mainly present on the left hillslope, where the scree slope reaches its maximum accumulation: “from a naturalistic point of view, it is probably the most valuable association of the whole valley, if not of the whole trieste karst” (poldini et al., 1978). “another distinctive feature of the northadriatic “dripeto” is the extremely high percentage of endemic iliric-balkanic species, which makes it rank first among all other karst associations in this respect, with a record of 53.3%” (poldini et al., 1980). furthermore, given the severe microclimate conditions characterising this hill slope of the rosandra valley, scree cenosis shows a particularly high presence of orophytes (plant species that grow in mountain areas) at exceptionally low altitudes, probably the lowest recorded in their diffusion area. the presence of alpine elements is highly significant in the rosandra valley, because it bears witness to the past phyto-historical events that occurred in the valley itself. according to the experts, during the quaternary climate oscillations, a penetration of the alpine flora (in cold periods) and of the mediterranean flora (in hot periods) occurred, whose traces were almost completely cancelled by the local illyrian flora that constitutes the current karst vegetation. many of them managed instead to survive in the rosandra valley thanks to its high microclimate variety, thus enhancing the cultural value of the studies on and the protection of the valley. the karst heath develops on monte carso and monte stena banks, where the slope is gentler and rocks appear next to the scree slope. it is a discontinuous herbaceous formation growing between the outcropping rocks, a typically zoogenous association due to the century-long pasturing activity on deforested areas. its origins probably date back to the brass age (approximately 1800-900 bc), which saw the insurgence of pasture farming on the karst territory. given the constant presence of centaurea rupestris and of carex humilis, this pasturing cenosis has been called “cariceto-centaureto”. besides these species, the heath presents the most typical karst elements, among which numerous endemic species can be found, mainly of illyrian origin (such as genista tergestina, pulsatilla montana, jurinea mollis, etc.). where the iron-debris nappe becomes particularly abundant, the heath also features sesleria juncifolia, a gramineae plant with rigid thin leaves and large clumps, particularly suitable to resist to the ice-cold gusts of winter bora. where rocks combine with particularly dry soils, some elements of stipa eriocaulis can be found, an elegant gramineae plant of mediterranean origin with long plumes fluttering in the wind (from which the vulgar italian name of “lino delle fate” (fairy flax). under conditions of exposure to the south, marked steepness and strong substrate permeability, the heath gives way to a steppe-like grass formation, where the illyrian elements decrease in favour of mediterranean species. this association reaches its maximum flowering period between late summer and autumn, and thrives on the rocky hill slopes over the old stone laundry in moccò and, on the hill slope on the orographic right, on the slope dominating the rail tracks at the entrance of the first gallery. the presence of different species of mediterranean origin is highly valuable, because these plants, as the alpine ones, have witnessed past climatic conditions. the typical karst scrub forest is mainly constituted by low-stemmed ostrya carpinifolia and fraxinus ornus trees and, despite being the most frequent cenosis in the trieste karst, in the rosandra valley it acquires some new peculiarities. first of all, it is of primary origin (poldini et al., 1978), whereas on the rest of the karst territory it developed after the cutting down of the great oak forests (which began during hillforts times, approximately brass age). this association is precious for the consolidation of unstable slopes, thanks to the development of rooting apparatuses, and is enriched by the presence of elements that are typical of fresh and humid habitats where it declines towards the rosandra canyon-like depression. it is worth noticing the presence of abundant blooming of galanthus nivalis and the frequency of polypodium interjectum, species typical of humid and shadowy rocky habitats. the karst wood is a tree formation characterised by the presence of sessile oaks and turkey oaks (cerri) next to the highly developed oak wood that probably covered the karst soil in prehistoric times, prior to its destruction at the hands of man. this association develops in the coolest and most humid small valleys, where colluvial soils accumulate. the fresh habitat, also enhanced by the tree-crown closure, enables the growth of woodland species typical of central europe (such as erythronium dens-canis, hepatica nobilis, asarum europaeum, etc.). this oak wood is mostly developed in the higher part of the valley, on a marlyarenaceous substratum. the rosandra valley is furthermore enriched by the presence of riparian spinneys, which are a rarity for karst soils, poor in surface hydrography. the most abundant species are salix purpurea, alnus glutinosa e populus nigra, as regards trees, and petasites hybridus e viola alba as far as the undergrowth is concerned. the plateau of s. servolo (monte carso) and monte stena are characterised by austrian black pine 192 f. cucchi et al. (pinus nigra) pinewood. these reforestation processes began in the second half of the xix century, when almost the whole karst area was completely bare due to the deforestation started during the brass age with a view to acquiring new pasturelands. in the rosandra valley, pinewoods are now formed by trees of advanced maturity, which are progressively being substituted by the pressing karst scrub forest that has been developing inside the pinewood in the last decades. worth mentioning is also the presence of species that are either rare or scarcely widespread in the adjoining areas: lilium bulbiferum, lilium carniolicum (two out of the three lily regional species), moehringia tommasinii (endemic species, that is species that grow spontaneously only in the area they are native to), asplenium lepidum (most rare fern of mediterranean distribution), digitalis laevigata, platanthera chlorantha, dactylorhiza maculata, gymnadenia conopsea, the most rare genista januensis and genista holopetala. 6. considerations on fauna as far as the local fauna is concerned, the rosandra valley presents almost all the species that populate the karst area. it is furthermore enriched by some of the species that are usually found in humid ecosystems, particularly rare in the karst environment. as for the mammal fauna, the roe deer is quite widespread, so that it can also be directly sighted during the day. this ungulate mammal frequents the karst scrub forests and clearings. another mammal belonging to the cervidae family that can sometimes be found in the valley is the red deer (cervus elaphus), coming from nearby slovenia. near to water ponds, it is possible to find traces of the presence of the wild boar (sus scrofa). among the rodents, it is worth mentioning the edible dormouse (glis glis), the red squirrel (sciurus vulgaris), which regularly frequents the pinewoods, the water vole (arvicola terrestris) and the yellow-necked mouse (apodemus flavicollis). also two hedgehog species can be found: a western (erinaceus europaeus) and an eastern one (erinaceus concolor), probably competing with each other because they share the same diffusion area in the karst environment. the hare (lepus europaeus), once common, is now threatened by the introduction of the common european rabbit (oryctolagus cuniculus) and by the shrubs spreading in the karst area. as far as the carnivores are concerned, one of the most widespread species is the red fox (vulpes vulpes), particularly precious from an environmental point of view because it also feeds on carrion, thus contributing to preventing the onset of various diseases. the badger (meles meles), the beech marten (martes foina), the polecat (mustela putorius) and the weasel (mustela nivalis) are the mustelids present in the rosandra valley: they are difficult to sight, though, because of their nocturnal habits. during the last years, the sporadic presence of great carnivores has been noted. traces and sighting prove the presence, or at least the passage, of the brown bear (ursus arctos) and of the lynx (lynx lynx), whereas during the last ten years the presence of the golden jackal (canis aureus) has been ascertained. as far as bird species are concerned, the valley hosts a few blue rock-thrush (monticola solitarius) couples. the blue rock thrush is a strongly territorial bird belonging to the turdidae family, a rocky species whose diffusion area is limited to the three european peninsulas the iberic, the italian and the balkan peninsula – and whose males have a metallic-blue plumage colour. the rock partridge (alectoris graeca) is a blue-greyish member of the phasianidae family that perfectly camouflages itself thanks to its colour being quite similar to that of limestone rocks. it is a typical species of the karst heath, once largely widespread and now only rarely present, which can be considered on the verge of extinction due to the spontaneous reforestation of the abandoned pasturelands. the progressive disappearance of the species usually associated with grass formations goes hand in hand with the simultaneous diffusion of the species that nest inside low-stemmed trees, such as the rock bunting (emberiza cia), a quite common species, easy to observe. in the winter months, also the wall creeper (tichodroma muraria) and the crested tit (parus cristatus) find shelter in the rosandra valley. in particular, the presence of this tit and of the coal tit seems to be ascribable to the black-pine pinewood reforestation process, which leads species normally nesting on the alps at an altitude of over 800 m to nest at lower altitudes. as far as the diurnal birds of prey are concerned, the following species can be sighted: the common buzzard ( buteo buteo), the northern goshawk (accipiter gentilis), which nests in the pinewoods close to clearings, the common kestrel (falco tinnunculus), which nests on the rocky walls above the old railway line, and the sparrowhawk (accipiter nisus), which, though only 20-30-centimetre tall, hunts small birds in the thick karst scrub forest. till some years ago, also the eagle owl (bubo bubo), the largest member of the strigiformes order, used to nest on the valley walls. still present now are the barn owl (tyto alba), the scops owl (otus scops), the little owl (athene noctua) and the tawny owl (strix aluco), which frequent and nest by the entrance of cavities. the rosandra valley is also populated by a rich herpetofauna, constituted both by definitely mediterranean species and by illyrian-balkanic and mediterranean ones. as happens for the vegetation, in fact, karst is respectively the eastern and northern expansion threshold of their diffusion area. the different species of reptiles and amphibians spread in the diverse valley habitats according to their trophic and/or reproductive needs. the most turbulent stretches of the rosandra creek are not suitable for the survival of amphibians eggs and larvae, whereas the calmer coves host the larvae of black and yellow fire salamander (salamandra salamandra), common toad adults (bufo bufo), yellow-bellied toad (bombina variegata), agile frog (rana dalmatina) and edible frog (rana esculenta). along the torrent banks, it is possible to find the grass snake (natrix natrix), species that feeds on amphibians larvae, and the minnow (phoxinus phoxinus). terrestrial amphibians such as the black and yellow fire salamander, the common toad, the edible and the agile frog can populate riparian scrub forests; as far as snakes are concerned, it is possible to find the grass snake, the aesculapian snake (elaphe longissima) and the western whipsnake (coluber viridiflavus carbona193geology and geomorphology ... rius). the most humid areas of karst scrub forests host the green lizard (lacerta viridis), the aesculapian snake, the western whipsnake and, rarely, the bulgarian viper (vipera ammodytes). away from the torrent, more thermophilous reptiles can be found, such as the green lizard, the dalmation algyroides (algyroides nigropunctatus) and the bulgarian viper. karst woods are characterised by the presence of the green lizard, the slow worm (anguis fragilis), the aesculapian snake, the western whipsnake, the smooth snake and the bulgarian viper, though the latter species is not particularly abundant due to the excessive insolation and the scarsity of preys. 7. hystorical considerations anthropogenic use of the rosandra valley is linked with environmental, geomorphologic and geological factors. the valley is a natural link between the sea and the inland, and has thus been always exploited for commercial traffic. the remains and antiquities found in the caves demonstrate that man had been present since prehistoric, mesolithic and neolithic ages. these and other peculiarities contributed to its exploitation both at the hands of prehistoric man and of the tourists-excursionists today. the whole area, and in particular m.te stena on the right, is characterised by both epigeal and underground karst phenomena: approximately twenty cavities are quite interesting from an archaeological point of view. in this respect it is probably worth mentioning the orsi cave (point 2, fig. 2) and the gallerie cave (point 16, fig. 2; fig. 9) (catasto, 2003). the first one is located on monte carso and consists of a single gallery that stretches over a total area of 135 m. the cave name comes from the finding – during exploration – of some ten skulls, jaws, femoral bones and vertebrae belonging to the cave bear species (ursus spelaeus), besides skulls and other bones of smaller-size animals. a particularly surveyed cave is the gallerie cave or finestre cave (point 16, fig. 2), located at the bottom of m.te stena, where archaeological excavation, started during last century by the pioneers of karst prehistoric studies, is still ongoing today at the hands of unauthorised researchers and antiquity collectors with no higher aspirations. the quantity of terracotta articrafts discovered here is higher than that found in any other karst cave, thus demonstrating that the cave had always been frequented by large human settlements throughout all prehistoric ages, thanks to the favourable environmental conditions. some specific ceramics findings suggest that vase-making activities were probably carried out in a chamber of the cave, probably the camino cave. two prehistoric constructions have also been recovered. they are two “hillforts”: one is located under monte carso top (point 18, fig. 2), where the ruins of the enclosing wall – probably ascribable to the iron age – are still visible today; the other is located on the top of monte s. michele, and dates back to protohistoric times too (point 19, fig. 2). the first (marini, 1985) appears to be the most widely extended hillforts in the area of trieste, and it also reaches the slovene territory. its safe and easily defendable geographic location made the complete building of the enclosing wall unnecessary, because the area was already partially protected by the impervious nature of the environment. from the hypothetical reconstruction of the hillfort of s. michele (canarella, 1989), it can be argued that three defensive concentric walls surrounded it; the only wall that is still visible today is the one enclosing the top of the mountain. the place is likely to have been frequented also during roman times, as the recovering of fibulae belonging to that period demonstrates. at the mouth of the valley, once left the settlement of bagnoli superiore, it is possible to walk along the line of the ancient roman aqueduct for approximately 700 m (point 20, fig. 2). this aqueduct is the only one present in the region: stretching over 14 km, it used to supply the town of tergeste with drinking water. it fed from the fonte oppia (oppia spring, point 13, fig. 2), a spring of water once flowing from the foot of a rock mass located along the rosandra creek, and now flowing from “stone ruins” located below the torrent level, as the british made the ancient rock mass explode during the occupation of trieste. also the “via del sale” (salt road) dates back at least to roman times: its path can still be walked along today on the orographic right of the torrent (point 21, fig. 2). the road was functioning above all during the hapsburg reign, and it served as a link between zaule salt marshes, near the village of muggia, and the towns and the inland villages. the road followed the ridge and also reached the church of s. maria in siariis (xii cen194 f. cucchi et al. fig. 9 gallerie cave. grotta delle gallerie. tury), which was completely restored in 1955, and which is still interesting today for the peculiarity of its location and for the panoramic view: on the orographic right, it is in fact possible to see the viewpoint of moccò (point 14, fig. 2), which rises on the remains of the medieval castle with the same name. built before 1100, it entirely dominated the rosandra valley and enjoyed the beautiful scenery of the gulf. according to the popular tradition, the castle is supposed to have had a gloomy and threatening atmosphere: it was built on a square plan and enriched by a gallery with merlons dominated by a smaller-size construction and by a tower. the location of the ancient castle, which offered an excellent viewpoint on the surrounding valley, made it a most coveted stronghold, above all during the conflicts waged by venice and trieste for the supremacy on commercial traffic. in 1511, the bishop pietro bonomo succeeded in conquering the castle, seizing it from the hands of the venetians; after a short time, the triestines themselves destroyed it to avoid re-conquering by the enemy. in the xvii century, the materials used for the construction of the castle were re-used to build the new castle, always on a square plan, which was seriously damaged immediately afterwards, during world war two and then irreparably destroyed by a fire: today only the foundations can be seen. another castle present in the valley is the draga castle (point 22, fig. 2), initially belonging to the vincumberg family and whose edification began in 1200 and continued until 1400. after passing from the hands of the venetians to the triestines, it was completely abandoned and destroyed in 1600. the castle, linked with the karst ridge through a drawbridge, was certainly connected with the salt road but the successive excavations and the building of the railway obliterated the initial course. today its ruins can be seen on the rocky spur in slovenia. thinking of recent times, the layout of the old railway line needs mentioning (point 3, fig. 2). the old railway line connected the hapsburg port of maria theresa times to vienna and ljubljana; it was started in 1887 and used until 1959. located on the orographic right of the rosandra creek, it is today a classical and beloved path to walk along, offering a wonderful view of the whole valley and leading from s. antonio in bosco and from s. lorenzo both to the villages of draga s. elia and bottazzo. this path is currently being reevaluated, also thanks to its conversion into a cycle-track linking trieste with draga s. elia and with slovenia as far as erpelle. at present, both the rosandra valley stretch (as far as the border between italy and slovenia) and part of the campanelle s. antonio in bosco stretch have already been completed, whereas the town and the slovene stretches will take longer to complete. to conclude this brief but not exhaustive digression on man and the valley, what still needs to be mentioned is the second cai mountain shelter at the lowest altitude in italy: the “rifugio premuda” (point 6, fig. 2). located at the entrance of the rosandra valley, it was opened in 1940, as a legacy of the mountaineering school founded in the thirties by emilio cornici. the valley is still today an important destination for excursionists and nature-lover tourists, for speleologists and mountaineers. 8. conclusions the physical and environmental peculiarities of the rosandra valley were officially recognised by law in 1996, with the regional law no. 042 of 30/9/1996, chapter ii, concerning parks and reserves, which declares "the establishment of the regional natural reserve of the rosandra valley”, defined by art. 2 as “… a territory characterised by a high-level natural and environmental quality, whose conservation aim prevails over other objectives…” in parallel, in compliance with 79/409 and 92/43 eec directives, put into force by the ministerial decree of 3/4/2000, the area is included both in the special protection areas and in the sites of community interest. special protection areas, disciplined in compliance with 79/409/eec directive, are those areas that are suitable – due to their extension and/or geographical location – for the protection of the endangered bird species as referred to in the annex i of the aforementioned directive concerning the protection of bird wildlife. sites of community interest are defined as follows by 92/43/eec directive: “… sites that, within the bio-geographical area/areas they belong to, significantly contribute to the adequate conservation or restoration of natural habitats as described by annex i, or of a species as described by annex ii, and that can furthermore significantly contribute to the coherent approach stated by nature 2000 as referred to in art. 3, and/or that significantly contribute to the protection of biodiversity in the pertinent bio-geographical area/areas”. so far, the rosandra valley has always been attached “special” importance, due to its high environmental value. as previously stated, its park is also a valuable and unique geological, historical and geomorphologic heritage. this is the reason why the valley can be considered a suitable candidate for the geopark status, according to the definition provided by the 29th unesco general conference (paris, october 24 – november 12, 1997): “a geopark is an area that has a peculiar geological heritage and a sustainable territorial development strategy… it ought to include a certain number of extremely important geological elements, in terms of scientific quality, rarity, aesthetic characteristics or educational value. the majority of the areas included in a european geopark are supposed to be part of the abovementioned geological heritage, but their interest can also reside in archaeological, environmental, historical or cultural values”. references cannarella d. (1989) la val rosandra edizioni itinerari carsici 3 edizioni italo svevo, trieste. chersi c. (1984) itinerari del carso triestino tipografia nazionale, 214 pp.. cucchi f., pirini radrizzani c. & pugliese n. (1989a) the carbonate stratigraphic sequence of the karst of trieste (italy) mem. soc. geol. it., 40, pp. 3544. cucchi f., vaia f. & finocchiaro f. (1989b) the geology of t. rosandra valley (karst of trieste, 195geology and geomorphology ... italy) -mem. soc. geol. it., 40, pp. 67-72. cucchi f., potleca m. & zini l. (1998) origin and development of cave system in the rosandra valley (classical karst italy) acta carsologica, ljubljana, 27/2, pp. 63-74. direzione regionale pianificazione territoriale (2003) catasto regionale delle grotte regione autonoma friuli venezia giulia. gherlizza f. halupca e. (1988) spelaues. monografia delle grotte e dei ripari sottoroccia del carso triestino nelle quali sono stati rinvenuti resti di interesse archeologico club alpinistico triestino (gruppo grotte), trieste. hottinger l. (1997) shallow benthic foraminiferal assemblages as signals for depth of their deposition and their limitations bull. soc. géol. fr., paris, 4, (168), pp. 491-505. marini d. (1985) guida alla val rosandra commissione grotte “e. boegan”, tipolitografia mario cozzi, trieste. onofri r. (1982) caratteristiche geolitologiche e geomeccaniche del flysch nella provincia di trieste studi trentini di scienze naturali, acta geologica, 59, pp. 77-103. placer l. (1981) geologic structure of s.w. slovenia geologija, ljubljana, 24/1, pp. 27-60. poldini l. (1989) la vegetazione del carso isontino e triestino. studio del paesaggio vegetale fra trieste, gorizia e i dintorni adiacenti edizioni lint, trieste, 317 pp. poldini l., goldstein m. & martini f. (1978) guida all’escursione botanica della val rosandra edizioni italo svevo, trieste,. 51 pp. poldini l., gioitti g., martini f. & budin s. (1980) introduzione alla flora e alla vegetazione del carso. carsiana (giardino botanico) edizioni lint, trieste, 307 pp. potleca m. (1997) carsogenesi della val rosandra tesi di laurea in scienze geologiche inedita, università degli studi di trieste, 137 pp. regione autonoma friuli venezia giulia, direzione regionale della pianificazione territoriale, & cai club alpino italiano, società alpina delle giulie, commissione grotte eugenio boegan la grotta dei sogni ufficio stampa e pubbliche relazioni della regione autonoma friuli venezia giulia, graphart snc. various authors (1981) convegno internazionale sulla val rosandra (mednarodni seminar o dolini glinščice) bagnoli (boljunec), pp. 178-195, pp. 300-321, pp. 696-720. 196 f. cucchi et al. imp.massoli&novelli the main geomorphosites of the egadi islands (sicily, italy) raniero massoli-novelli via della mendola, 85 00135 roma, email: massoli@tiscali.it abstract: r. massoli-novelli, the main geomorphosites of the egadi islands (sicily, italy). (it issn 0394-3356, 2005). this article describes the main geological and geomorphological features of the three main egadi islands: favignana, levanzo and marettimo. these islands, which are essentially made up of mesozoic carbonate rocks, are considered as the continuation in the sea of the north-western sicilian chain. in addition, the main geomorphosites of these three islands are identified for the first time: these are the numerous, significant coastal caves. particular emphasis is given to natural and anthropogenetic geomorphosites related to the pleistocene bioclastic calcarenite caves present in favignana, an ancient site of intense quarrying activities. riassunto: r. massoli-novelli, i principali geomorfositi delle isole egadi (sicilia, italia). (it issn 0394-3356, 2005). vengono evidenziate le principali caratteristiche geologiche e geomorfologiche delle tre maggiori isole delle egadi, favignana, levanzo e marettimo, costituite essenzialmente da rocce carbonatiche mesozoiche e considerate la prosecuzione in mare verso ovest della catena nordoccidentale della sicilia. vengono poi individuati per la prima volta i principali geomorfositi delle tre isole, in gran parte costituiti dalle numerose e rilevanti grotte costiere. particolare risalto viene anche dato ai geomorfositi, naturali ed antropici, relativi alle cave di calcareniti bioclastiche pleistoceniche esistenti a favignana, luogo di antica ed intensa attività estrattiva. keywords: geomorphosites, calcarenite, egadi islands, italy. parole chiave: geomorfositi, calcarenite, egadi, italia. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 137-143 1. introduction and general geological setting the egadi archipelago is formed by three main islands – favignana, levanzo and marettimo – and the islets of maraone and formica. all these islands are geologically linked to the adjacent mainland. in other words, the egadi are the continuation in the sea of the backbone chain of northwestern sicily (fig. 1). the basic geological composition of this archipelago corresponds to calcareous-dolomitic rocks, ranging in age from the triassic to the miocene. subsequently, layers of sandstones were deposited on top of the carbonate rocks. in particular, bioclastic calcarenites crop out abundantly on the largest island of favignana. they are typical poorly cemented, easily workable, yellowish calcareous limestones rich in pelecypods, especially the pecten genus. owing to these characteristics, since the 1700s this stone has been called “tufo” (i.e., tuff; a similar wrong definition has been given to the stones of matera in basilicata). these limestones have been intensely quarried through time. no detailed studies have been ever carried out on this interesting stone, although it appears to be quite similar to the proximal bioclastic calcarenite outcrops of the lower pleistocene along the coast of marsala (ruggieri et al., 1975) and in san vito lo capo (antonioli et al., 1994). the presence of compact calcareous-dolomitic rocks explains the two essential geomorphological characteristics of the egadi islands: cliffs and high reliefs in all the islands, especially in the two smaller ones, and many large caves. the highest peak is mt. falcone in marettimo, which reaches a height of 686 m. not only is this island the furthest from the sicilian coast but it is also the one most affected by tectonic processes, with numerous overthrusts and transcurrent faults (abate et al., 1995, 1996). favignana is the largest of the egadi islands. owing to its shape, it is compared to a butterfly: at the centre of the island, a north-south ridge of mesozoic calcareous-dolomitic rocks stands out, reminiscent of a butterfly’s body. at the sides, calcareous marine sediments to the west and arenaceous marine sediments to the east were subsequently deposited on these hard and compact carbonate rocks, forming two small plains: the butterfly’s wings. in the plain to the east, abundant strata of pleistocene bioclastic calcarenites crop out (the “tufo” or favignana stone previously mentioned). these rocks, between a few centimetres to about 30 cm thick, show a generally sub-horizontal bedding. the calcarenite is a marine, very rich in fossils (pelecypods, corals, remains of fish, etc.) calcareous sandstone. the isle of levanzo, which is the smallest of the three main egadi islands, is famous for its rugged land138 r. massoli-novelli scape and absence of beaches. also marettimo, the most mountainous of the egadi islands, has practically no beaches. from the geological standpoint, it is older than the other two islands, since it is mostly composed of triassic-lias limestones and dolostones (incandela, 1996). because of its position in the open sea, surrounded by a deep sea floor, marettimo is often windswept and pounded by westerly and northerly breakers. as a consequence, this island has a much more jagged coastline than levanzo and favignana. 2. the main geomorphosites of the egadi islands the main geomorphosites identified on each island are here below illustrated with progressive numbers, with reference to the map in fig. 1. 2.1 isle of favignana the excursion starts from the south, from the “scindo passo” cliff, where a long vertical rock wall of tectonic origin is found. this area is characterised by fig. 1 – schematic geological map of the egadi islands. numbers refer to the geomorphosites listed in the text. cartina geologico-schematica delle isole egadi: i numeri si riferiscono ai geomorfositi elencati nel testo. the presence of large, unstable limestone boulders which have caused several rock falls. this cliff and the rock fall materials make up an interesting geomorphosite (1), easily observable from the asphalt road. to the south, another geomorphosite is found: the “preveto islet” (2), which is made up of mesozoic limestones. this geosite is the obvious continuation into the sea of the favignana ridge. to the west, the perfectly circular natural inlet of cala rotonda is found. inside it, a small geomorphosite named the “arch of ulysses” (3) is located. this is a remarkable, thin natural arch rising from the sea. all the western coast is made up of vast sub-horizontal outcrops of limestones and calcareous breccias and is an important example of an ancient sub-aerial plain which was later reworked by the sea. it contains innumerable microforms of the karren and pot-hole types, which are particularly visible in the cala grande area. it is therefore possible to identify a karst coastal plain of the cala grande geomorphosite (4). to the north, high on a cliff towards punta faraglione, there are two large karst caves very close to each other. the one known as “grotte dell’ucceria” has two entrances and important prehistoric artefacts were found inside it. this two-cave complex makes up an important karst-type geomorphosite (5). we shall now describe the eastern side of favignana, with its calcarenite sandstones and the previously mentioned “tufo” quarries. for many centuries this “tufo” rock was exploited as the most important economic activity of this island, together with fishing and farming. the quarrying of this material goes back to very ancient times – certainly roman times – but the peak of quarrying activities dates back to the period between the 17th and 19th centuries. many palaces in tunis were built with favignana “tufo”. the same rock was used for the reconstruction of messina after it had been destroyed by the earthquake of 1908. indeed “tufo” has always typified the isle of favignana. apart from making up most of the geological landscape, it can be observed everywhere as building material: numerous houses and stone walls dividing land properties are made of it. there are about 150 existing quarries, of which most are open cast quarries or pit-like ones. on the other hand, other quarries have been dug out underground. four groups of caves, which are the most interesting and representative of several types are here proposed as geomorphosites: “ancient quarries in the village of favignana” (6), in particular those next to the security prison. although there is no certainty about their age, it is 139the main geomorphosites of ... assumed that most of them were excavated between the 17th and the end of the 19th century. these sites are now utilised as gardens and small orchards; “ancient coastal quarries of san nicola” (7), whose floors have now been covered by sea advancement for a depth of about 20 cm, and where the ancient submerged excavation frames are still perfectly visible (fig. 2). the calcarenites are very rich in fossils here, especially in pecten specimens. it is assumed that they were exploited between the middle ages and the last century, in analogy with the nearby coastal quarries of bioclastic calcarenites of san vito lo capo, which are also submerged (antonioli et al., 1994). recently, in the area of san nicola, the skeleton of a cetacean in a horizontal position, embedded in calcarenite, was found, together with layers of pelecypod shells. this large marine mammal was probably grounded on the beach (massoli-novelli, in press); “ancient/modern quarries of cala rossa” (fig. 3), here different types of quarries are found: coastal open cast quarries (8) and underground excavated quarries (9), with the presence of numerous, considerable sedimentation structures, in particular cross-bedding, which were exploited manually in the past centuries; “recent quarries of setteminne-torretta” (10), these are often large pit-type quarries, up to 30 m deep, which have been worked by means of cutting machines. many of them were recently abandoned, although some are still active in order to guarantee the required material for restoring the many old houses built of calcarenite stones. as has been suggested by many authoritative sources, the favignana “tufo” quarries should be reclaimed for cultural and geotourism purposes, as, for example, a quarry museum or an earth museum. furthermore, in setteminne there are two large contiguous quarries which together make up an interesting geomorphosite (11). they are both pit-type quarries; the first one is abandoned but it still has a typical residual fig. 2 – aerial view of the cala rossa ancient “tufo” quarries (pleistocene bioclastic calcarenite), isle of favignana: the resulting landscape is similar to that of an abandoned city (photo by tamagnini). le antiche cave di “tufo” (calcarenite bioclastica pleistocenica) di cala rossa, isola di favignana, osservate dal cielo: il paesaggio che ne deriva risulta simile a quello di una città abbandonata (foto tamagnini). 140 pillar of the excavation activities (fig. 4), whereas the second one has a regular square shape which would be very suitable as a stage for open-air summer shows by night. along the south-eastern coast another natural geomorphosite is found: the “grotta perciata” (12). here the sea hollowed out a cave which has partially collapsed, leaving only an interesting arch and a little shelter for two or three fishing boats. further to the south-east, the “cala azzurra” is found, which is another coastal geomorphosite (13) of great scenic value, with the only sandy beach of the island, which is divided into two parts by an outcrop of compact calcarenite. finally, after this series of prevalently coastal geomorphosites, an outstanding internal site is found on top of the mesozoic carbonate ridge at the centre of the island: mount santa caterina (14), at an altitude of 314 m a.s.l., where the fort bearing the same name rises and from which a spectacular view over the village, the harbour and the calcarenite quarries can be enjoyed. 2.2 isle of levanzo levanzo is a small hamlet located in a very beautiful inlet on the island’s southern coast. as soon as one arrives there, an interesting geomorphosite (1) is immediately noticeable: it is made up of a large, steep, tectonic pinnacle of mesozoic carbonate rock, subsequently modelled by erosion, which hangs over the sea and the hamlet. following the path to the west, another similar geomorphosite (2) is immediately visible: the well-known “faraglione di levanzo”, an imposing block of mesozoic dolomitic limestone, which was first isolated by tectonics and then by sea erosion. proceeding uphill towards the “grotta dei genovesi”, one crosses an area named “la fossa”, which is another geomorphosite (3) corresponding to a karst depression, the only one on the island. this site was cultivated up to a few years ago r. massoli-novelli fig. 3 – the s p e c t a c u l a r pilastro calcarenite quarry, in setteminne of favignana. this is a recently opened quarry, as witnessed by the marks of the digging machines. it has now been abandoned and, hopefully, should be reclaimed and appraised (photo by massoli-novelli). la spettacolare cava di calcarenite del pilastro, in località setteminne di favignana, una cava recente come mostrano i segni delle macchine tagliatrici, abbandonata da poco ed in attesa di una auspicabile v a l o r i z z a z i o n e (foto massolinovelli). fig. 4 – ancient calcarenite coastal quarry in san nicola, isle of favignana. it probably goes back to medieval times and its floor is at present under 20-30 cm of sea water (photo by massoli-novelli). antica cava costiera di calcarenite a san nicola, isola di favignana, di età probabilmente medioevale, dove il pavimento è oggi ricoperto da 20-30 cm di acqua di mare (foto massolinovelli). 141 and the residual soil, with its typical reddish colour, has been subject to fertilisation. the site is surmounted by an ancient homestead of the florio family. the “grotta dei genovesi”, which is located on the island’s western coast, is the main attraction of levanzo. owing to its artistic palaeolithic engravings and neolithic paintings, this cave is to be considered an important geomorphosite (4). another peculiarity of this cave is given by the strange scarcity of stalactite/stalagmite concretions, probably due not only to the scarce rainfall of this island but also to the presence of overlying clayey beds. this cave was formed at the foot of a rock wall made up of monoclinal, seaward-dipping thick beds of mesozoic limestone. these strata show a westward dip-downstream attitude. in proximity of this cave, both on the rock wall overhanging the entrance to the cave and along the underlying coast, the strata crop out extremely well and with considerable regularity. the land journey along levanzo’s western coast is quite difficult but eventually one reaches cala tramontana, which is characterised by a steep calcareous-dolomitic falaise and where a geomorphosite (5) made up of a series of caves named “grotte di cala tramontana” is found. these other caves are all located at nearly the same altitude as the grotta dei genovesi, some 10-20 m above the present sea level (fig. 5). the cala tramontana caves are larger than the more popular grotta dei genovesi and they too contain prehistoric and historic remains. geomorphosite no. 6 is capo grosso, the island’s northern point. this site is particularly interesting because tectonic and erosional processes have shaped it as if it had been cut through, giving origin to a magnificent falaise where thick strata of dolomitic limestone are particularly well exposed. this beautiful outcrop shows west-dipping layers at an angle of about 45°. all the eastern coastline of levanzo is of the falaise type. here, another geomorphosite (7), which is interesting not only from a scenic standpoint, can be admired at capo calcara, where the strata of mesozoic dolomitic limestone were cut by a visible n-s oriented fault which has created this little bay. 2.3 isle of marettimo by sailing from the harbour of marettimo and moving counter-clockwise, it is possible to circumnavigate the whole island and have a good view of the numerous geomorphosites located along the coast. most of these, are coastal caves, whose origin is mainly to be ascribed to the numerous faults which characterise this island (abate et al. 1996). soon after the small beach of bagno di fimmine, the interesting “cave of the camel” (1) appears, whose name is derived from an adjacent rock similar in appearance to the head of this animal. this cave was affected by the collapse of part of its vault, and the sea water inside it is crystal-clear. to the north, one of the most prominent geomorphosites of marettimo is found: the small promontory of “punta troia” (2), well-known for the ancient castle that rises on top of it. this site is also important due to particular geological features, such as the perfect semi-arch which links the promontory to the island, thus creating a particularly striking landscape. behind punta troia, the “cave of thunder” (3) is found, so called after the roar created by the waves that after breaking on the outer wall of the cave, are sucked out through a sort of siphon. adjacent to the cave of thunder, another interesting geomorphosite (4) is found: a gigantic “talus fan”, indeed the largest fan present on the island. this landform stretches from a canyon high on the cliff as far as the sea-shore, with considerable scenic effect. all the island’s north-western coast, with its jagged coastline and spectacular cliffs rising towards the top of mt. falcone (659 m a.s.l.), forms an extremely beautiful and rugged landscape. the “cave of the pipe” (5) is the first to be found. this has a high educational value since, more than any other cave, it clearly shows that the origin of the coastal caves is often due to tectonics. in this case, the cavity was developed along a long, partly collapsed, vertical fault. also “ficarella cave ” (6) was formed at the foot of a long fault: its rock walls also show evident marks of sea breakers at about 5 m a.s.l. shortly afterwards, one arrives at what is considered the most interesting cave, the geomorphosite (7) named “bombarda cave” (fig. 6), near the headland bearing the same name. the cave’s peculiarity is not so much given by the fault stretching across its vault but rather by its geological structure, with thick layers of mesozoic dolomitic limestone in sub-horizontal attitude. practically, the cave shows long, horizontally striated walls, slightly changing in colour. owing to an optical effect the horizontal striae seem to enhance the already considerable depth of this cave. after bassano point – the southernmost tip of the island – and before returning to marettimo, a coastal geomorphosite (8) is found along the regular eastern coast. it consists of one of the very few small beaches of the island, the so-called “praia nacchere”. here, a considerable fault can be observed just at the the main geomorphosites of ... fig. 5 – the steep cala tramontana coastline of the isle of levanzo. it is made up of mesozoic dolomitic limestones and located north of the well-known grotta dei genovesi. the “grotte di cala tramontana” geomorphosite, made up of three main karst caves containing prehistoric finds, is also visible (photo by tamagnini). la ripida costa di cala tramontana, isola di levanzo, composta di calcari dolomitici mesozoici ed ubicata a nord della nota grotta dei genovesi; si nota il gemorfosito “grotte di cala tramontana” dato da tre cavità carsiche principali, anch’esse con reperti preistorici (foto tamagnini). 142 end of the sandy beach. finally, by following a rather demanding trail starting from the village, it is possible to ascend towards geomorphosite (9), which is the island’s highest peak: mt. falcone, rising to an altitude of 686 m a.s.l. 3. conclusions the geomorphosites of the egadi islands are numerous and interesting. they were all formed within two main rock types: i) mesozoic dolomitic limestones, found in the three main islands, and ii) pleistocene bioclastic calcarenites present in favignana. the geomorphosites resulting from carbonate rocks are mainly coastal caves, stacks, pinnacles and talus fans. on the other hand, the geomorphosites formed within calcarenite rocks are both natural – showing considerable examples of cross-bedding and other sedimentation structures – and anthropogenetic, linked to ancient and intense quarrying activities. on the whole, thirty geomorphosites have been identified as examples of major and immediate interest: 14 in favignana, 7 in levanzo and 9 in marettimo. finally it should be noticed that a few years ago the egadi islands were declared a protected marine area (amp) managed at first by the local harbour-office and after by the favignana municipality. however, at present no educational-divulgative material is yet available on the important and interesting geological-geomorphological features of the egadi islands, which should be better understood and appreciated in order to promote sustainable fruition of these natural resources. unfortunately, this is not an isolated situation among the eighteen italian protected marine areas. acknowledgements the author is grateful to professors sandra piacente, from the university of modena and reggio emilia, and francesco torre from the university of trapani, for their critical review of the typescript and useful advice. r. massoli-novelli fig. 6 – la bombarda cave, located along the western coast of marettimo, is characterised by thick layers of mesozoic dolomitic limestones with a sub-horizontal attitude. along the vault, the fault at the origin of the cave is quite evident. a common tectonic origin characterises most of the numerous karst cavities found on this island (photo by massoli-novelli). la grotta bombarda, ubicata lungo la costa occidentale di marettimo, è caratterizzata da bancate di calcari dolomitici mesozoici in giacitura 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(2002) geositi nel paesaggio italiano: ricerca, valutazione e valorizzazione. un progetto di ricerca per una nuova cultura geologica geologia dell’ambiente, 2, sigea, roma. ruggieri g., unti a., unti m. & moroni m.a. (1975) la calcarenite di marsala (pleistocene inferiore) e i terreni contermini boll. soc. geol. it., 94, pp. 1623-1657. torre f. (1980) levanzo la grotta del genovese comune di favignana assessorato regionale beni cultuali e pubblica istruzione. torre f., (1988) notazione a proposito delle oscillazioni del livello del mare nel trapanese durante il pleistocene medio-superiore sicilia archeologica, anno xxiii, no. 74 , trapani. ulzega a. & orru p. (1989) piattaforma continentale delle egadi in: v. agnesi, t. macaluso, a. ulzega, guida alle escursioni, gruppo nazionale geografia fisica e geomorfologia, c.n.r., trapani, 27-30 giugno 1989, università di palermo. 143the main geomorphosites of ... imp.bottari& tectonic genesis of the salt marshes on the sicilian coast of the straits of messina (sicily) antonio bottari1, carla bottari2 & pietro carveni3 1osservatorio sismologico, università di messina, via osservatorio 4, 98121 messina, italia. fax +39090363533, 2istituto nazionale di geofisica e vulcanologia, via di vigna murata, 605 00143 roma, italia. fax +39065186507 3dipartimento di scienze geologiche, università di catania, corso italia 57, 95129 catania. fax +39095412646, e-mail carveni@unict.it abstract: bottari a., bottari c. & carveni p., tectonic genesis of the salt marshes on the sicilian coast of the straits of messina (sicily, southern italy). (it issn 0394-3356, 2005). based on historiographical, geophysical and seismological data a detailed geological and geomorphological survey has been carried out to reconstruct the genesis of two sicilian salt marshes. these salt marshes, called pantano piccolo and pantano grande, are located respectively on the northern and southern seashore of the coastal plain of peloro cape. the peloro cape is placed at the northern opening of the straits of messina and together with the two salt marshes, constitute a complex eco-system of great interest because of the multiple implications of anthropic and naturalistic nature. the result of geological and geophysical surveys shows that the origin of these salt marshes was due to the activity of some normal faults that conform peloro cape peninsula and that control the level of coastal plain. the shallow basin of pantano grande (big marsh), has a lengthened shape along the ionian coastline. it is delimited to n by a normal fault that set the limits to s of the horst of granatari hill and to s from some small faults that conform the southern shore. the southern coastline of pantano grande is composed by a narrow strip of alluvium deposits that separate the salt marsh basin by ionian sea; here along the coastline a narrow strip of paleontologically sterile conglomerate outcrops. otherwise, the atypical morphology of pantano piccolo (small marsh) is characterized by a high depth (m = 28 m) compared with its horizontal dimensions; from the bathymetric analysis results that the facing tyrrhenian sea is less deep of the pantano piccolo basin till 600 m far from the coastline. the basin of this salt marsh is situated inside a small semi-graben n-s oriented and it is located in the coastal lowland that conforms to e the peloro cape peninsula. in short, the analysis of geomorphologic characteristics and the results of geological, geophysical and seismological surveys support a tectonic genesis for both the salt marshes. riassunto: bottari a., bottari c. & carveni p., genesi tettonica degli stagni salmastri ubicati sulla costa siciliana dello stretto di messina (sicilia). (it issn 0394-3356, 2005). lo stretto di messina è un graben che dall’inizio del pliocene ha subito un’intensa evoluzione; esso è limitato da un sistema di faglie nne-ssw lungo la costa siciliana e da un sistema di faglie ne-sw lungo quella calabra. la penisola di capo peloro, estrema propagine nord-orientale della sicilia, è situata all’imboccatura settentrionale dello stretto, ed è formata da una zona collinare con sviluppo ew, corrispondente ad un horst, delimitato a settentrione dalla faglia di mortelle ed a meridione dalla faglia di ganzirri; nella zona collinare affiora prevalentemente la formazione di messina, un deposito ghiaioso-sabbioso clinostratificato di facies deltizia, discordante su limitati affioramenti di conglomerati tortoniani, su lembi discontinui della serie gessoso-solfifera messiniana e di trubi infrapliocenici; al disopra della formazione di messina si trovano limitati affioramenti di sabbie a ostrea e, sopra di queste, livelli di sabbie a strombus bubonius. la zona collinare è bordata da una pianura costiera di larghezza variabile. tale pianura, che non supera 4 m di quota, è formata da ghiaie, sabbie e limi; al suo interno si trovano due specchi di acqua salmastra, denominati pantano piccolo e pantano grande, i quali costituiscono un importante e complesso ecosistema, di grande interesse per le molteplici implicazioni di carattere antropico e naturalistico. sulla base di dati di ricerche storiografiche, geofisiche e sismologiche, cui hanno fatto seguito rilievi geologico-geomorfologici di dettaglio, è stata ricostruita la genesi dei due pantani che è da attribuire all’attività di alcune faglie normali: il bacino del pantano grande, poco profondo, con forma a clessidra allungata parallelamente alla linea di costa ionica, è delimitato a settentrione dalla faglia di ganzirri ed a meridione da una serie di piccole faglie che ne conformano la riva; la linea di costa, che delimita a meridione il sottile cordone di depositi alluvionali che separano il pantano grande dal mare ionio, è marcata da un affioramento di conglomerato paleontologicamente sterile. il pantano piccolo presenta una morfologia atipica, caratterizzata da una grande profondità (m = 28 m) paragonata alle dimensioni orizzontali del bacino, da un gradiente batimetrico circa triplo di quello dell’antistante braccio di mar tirrenico che risulta essere meno profondo del pantano piccolo fino ad oltre 600 m dalla linea di costa. in sintesi, l’analisi delle caratteristiche geomorfologiche e dei risultati di indagini geologiche, geofisiche e sismologiche supportano una genesi tettonica per entrambi i pantani. keywords: straits of messina, coastal salt marshes, tectonics, morphologye. parole chiave: stretto di messina, stagni costieri salmastri, tettonica, morfologia. il quaternario italian journal of quaternary sciences 18(2), 2005 113-122 1. introduction the peloro cape peninsula, placed on the sicilian shore of the straits of messina, presents peculiar geomorphological characteristics which make it of notable morphotectonic and landscape interest (fig. 1). it is composed by a hilly zone along an e-w direction, and bounded by a coastal plain of variable width. in particular, the salt marshes of faro and ganzirri, called respectively pantano piccolo (small marsh) (fig. 1: pp) and pantano grande (big marsh) (fig. 1: pg), situated inside the coastal plain, constitute a complex ecosystem of great interest of anthropic and naturalistic nature. recently, the attention of environmental characteristics of this area was enlarged by proposing of realization of a bridge to connect the two shores of the 114 a. bottari, c. bottari & p. carveni straits of messina. among the unsolved problems of prevailing geological interest detaches that one relative to the genesis and evolutional history of the basins of pantano piccolo and pantano grande. with this aim, and starting from analysis of historiographical, geophysical and seismological data, some new geological and geomorphologic surveys have been carried out. 2. historiographic outlines the first known human settlement on the sicilian shore of the straits was located in the area between ganzirri and faro as shown by the finding of some pieces of pot that were brought to light in the 1960s excavation. the dating of this material between 2200-2000 bc provides a terminus post quem for the prehistoric village (biddittu et al., 1979). historical sources of roman age mention that the legendary town of risa, placed on granatari hill, collapsed during an earthquake and its remains fell down in the pantano piccolo. the same sources relate that two temples were once in the area between the two salt marshes. the first one was built by orion and was probably dedicated to neptune. remains of this building were brought to light in 1835, during the digging work of a waterflow to connect pantano grande to pantano piccolo (fig. 2: c3). the second temple was built in a third salt marsh, deep only 0.5 m, located between pantano grande and pantano piccolo. this temple was destroyed in roman times and the salt marsh was filled in (fig. 2: p1). indeed, at around ad 1500, only two marsh existed, pantano piccolo and pantano grande (maurolico, 1543). the material deriving either from the digging work of the first canal or from the digging work of a second canal, which was built in the 18th century to connect pantano piccolo (faro) with the ionian sea (fig. 2: c1), was used to drain a fourth small marsh (fig. 2: p2) which had formed between pantano grande and pantano piccolo (abbruzzese & genovese, 1952). in conclusion, the whole historiographical data documents that the area between the two salt marshes (pantano grande and pantano piccolo) was influenced by local subsidence in the last two thousand years which produced in different times another two small basins at least (fig.1: p1 and p2) that no longer exist as they were filled in by man. 3. geological and structural features of the peloro cape peninsula the peloro cape peninsula is the extreme northeastern tip of sicily, and forms the western shore of the straits of messina in a tract where the minimum distance from the calabrian shore is 3.2 km. the straits of messina is a graben which suffered an intense evolution at the beginning of the pliocene; it is bounded by fault systems in a nne–ssw direction along the sicilian shore and ne-sw fault systems along the calabrian shore; it was partially filled by transgressive plio–pleistocene deposits on a crystalline allochthofig. 1 geological sketch of the peloro cape peninsula. nous basement and mio-pliocene deposits (jacobacci et al., 1961). most authors affirm that the origin of the straits of messina can be attributed to lowering movements along normal faults which were active in the plio–pleistocene, although different opinions exist about movements along the structures, and for the number of tectonic phases which have resulted in the present day setting of the territory (selli, 1978; bousquet et al., 1980; ghisetti, 1981). the deepest geometrically geological formation in the stratigraphic succession which outcrops in the straits area is formed by pre-mesozoic high grade metamorphites, transposed as nappes in the mid miocene and making up part of the aspromonte unit; in particular, it features pegmatoid gneiss for the sicilian area (atzori et al., 1974) and high grade monzogabbro, augengneiss, paragneiss and micaschists for the calabrian shore (pezzino & puglisi, 1980). neogenic quartenary sediments relating to the filling of subsiding basins formed immediately after the mid – miocene orogenic transport phase, lie in transgression on metamorphic rocks. (barbano et al., 1978; lentini & vezzani, 1978). in particular, the polygenetic sterile base conglomerate evolved as a sandstone – clay alternation of the tortonian age (jacobacci et al., 1961), on which tongues of evaporitic limestone and messinian gypsum lie in sedimentary continuity; trangressional on these is early–pliocene white globigerine 115tectonic genesis of the salt ... marl (trubi) (jacobacci et al., 1961); early–pleistocene limestone deposits lie transgressive on all the formations described (lombardo, 1980 a; 1980 b) and on which lie the early-pleistocene argille di vito superiore; yet discordant on all the terms listed lies clinostratigraphic mid pleistocene gravel and sand from the formazione di messina (lombardo, 1980 a; 1980 b). still in discordance, late pleistocene terraced deposits, both in marine and continental facies, outcrop on this (ghisetti, 1981): the stratigraphic succession is closed and completed by alluvial fans, recent and present-day alluvial and beach deposits. the following succession outcrops in the survey area: 1) the formazione di messina: this consists of clinostratigraphic deposits, mainly delta facies, laterally passing to organogenic sandstone calcarenite, coastal facies sand and gravel; its thickness ranges between 70 and 250 meters; to the west of the study area, the formation lies in discordance on tortonian rocks, on the messinian ones of the serie gessoso solfifera and on trubi; because of faults, it is in contact with the metamorphic rocks of the aspromonte unit; the formazione di messina was recognized to be discordant and transgressive on the substratum (jacobacci et al., 1961) and was ascribed to the early and/or mid pleistocene; according to selli, (1978) it was formed in a river fed deltaic environment; according to sauret (1980) and barrier (1984), it was a regressive and diachronic fig. 2 map of the peloro cape peninsula with the bathymetry of surrounding seas; c1, linking canal between pantano piccolo and the ionian sea, c2, linking canal between pantano piccolo and tyrrhenian sea, c3, linking canal between pantano piccolo and pantano grande, c4, linking canal between pantano grande and ionian sea; p1 and p2 , assumed locations of two ancient marshes which are not more existing; x-y and y-z, shares of the sterile conglomerate outcropping along the shoreline of ganzirri – punta sottile; d1 and d2, geognostic boring locations (modified from carta dello stretto di messina, i.i.m., scale 1:30000). 116 facies due to centripetal progradation towards the centre of the straits, caused by a rapid uplift of the crystalline hinterland; 2) gravel and sand with ostrea: to the east of the papardo river, approximately 60 m above sea level, minute gravel lies in discordance and transgression on clinostratigraphic deposits of the formazione di messina, except for a sub-horizontal surface of marine erosion. this gravel is characterised by the presence of ostrea shells; higher up, this is followed by sand in which specimens of strombus bubonius and glycimeris have been found and which have been attributed to the tyrrhenian; the highest altitude of these sediments is about 85 m (bonfiglio & violanti, 1983); 3) terraced alluvial deposits: these are formed by gravel, sand and reddish silt with alluvial facies; cardium coastal facies are often present at the base; the elements that make up the deposit derive mainly from crystalline rock erosion from the aspromonte unit and secondarily by their sedimentary covering. they were related to tyrrhenian (hugonie, 1974); 4) recent alluvial and coastal plains: this term indicates deposits situated on the edges of naturally formed water channels; they are formed from gravel, sand and silt originating from metamorphic rocks and from the previously described conglomerate and gravel formations; their thickness range from one to tens of meters and occupy the edges of main rivers and the strip of coast that forms the extreme tip of the peloro cape, which enclose the two salt marshes in ganzirri and faro; inside coastal deposits there are lens of sterile conglomerate, about 1m thick, strongly cemented (bonfiglio & violanti, 1983); 5) eluvial and colluvial sheets: this is a strip which extends from the foot of the hilly area for several tens of kilometres and is made up of a brown-reddish, gravellysandy deposit, sometimes in the form of alluvial cones; its litho–structural characteristics and area distribution make it relative to the superimposition of successive accumulations of the slope declivity deriving from the weathering of previous territories; states of various inclinations can be seen along the man made trench, as a consequence of the trend of the sub-stratum; 6) present day alluviums and beaches: present day alluviums are found along the river beds; they originate from the erosion of previous terms and present a variable size; current beaches are formed by gravel fashioned by wave movement and currents. 4. geomorphological characteristics the peloro cape peninsula presents a smooth morphology, related more to the outcropping lithologies than the tectonic structures. it is characterized by a hilly range and a coastal plain which houses two salt marshes (fig. 1). the hilly range is formed by a series of small rises with flat peaks; the watershed descends gradually from the west to the east, separating the northern slope from the southern one. the northern slope is characterised by an average slope of 25% and a series of small streams. the southern slope is less sloping (17%) of the previous one, with numerous small and less pronounced streams. the width of the coastal plain varies from a minimum of 75 m in lido di mortelle on the northern coast, to a maximum of 1,750 m between granatari and peloro cape; the isobaths form a cusp on the extension of this alignment (fig. 1). the different trend of bathymetric gradient along the northern shore of peloro cape peninsula (tyrrhenian sea side) compared with that of southern shore (ionian sea side) is evident (fig.2). the ionian coast from messina to peloro cape is bordered by a coastal plain which is characterized by different morphological features: from messina to the outlet of the guardia river (fig. 1: fg), it lies in a roughly nne-ssw direction, with an approximately straight trend, modelled by small recesses and protrusions and is several tens of meters wide; at the outlet of the guardia river, the coastline diverts clearly towards ene and assumes a straight trend as far as peloro cape. in this last stretch, the width of the coastal plain is still several tens of meters wide as far as ganzirri, and from ganzirri beach to pantano grande it sharply widens reaching approximately 500 m (figs. 1, 2). along this coast the tidal currents which can reaches 7 knots have a strongly erosional influence on the shore (montenat et al., 1987; amore et al., 1988). the active tectonic from upper pleistocene until today carry an important rule in conditioning the geomorphological conformation of this area as pointed out by analysis of the paleoseismicity (valensise & pantosti, 1993), of the deformation/rupture/dislocation of superficial terrains observed after strong seismic events (lo perfido, 1909; baratta, 1910) and of the focal mechanism of earthquakes. the straits of messina area is characterized by high values of magnitude (m) of the strongest earthquakes occurred in the last 220 years (7.0 ≤ m ≤ 7.2). the 1908 seismic event (m = 7.2) was the most catastrophic event of the last century, with epicentre in the straits, focal depth h = 18 km and seismogenetic rupture along the ne-sw direction which was 45 km long and 14 km wide. the focal mechanism was normal with a strike-slip component, consistent with distensive stress condition (bottari et al.., 1986; bottari et al., 1989). among the major coseismic effects observed after the 1908 earthquake in the mesoseismic area should be pointed out the lowering of peloro cape terrains of about 20 cm, the subsidence/ ruptures along the southern slope of granatari hill and the underwater landslides along the ionic coast (lo perfido, 1909; baratta, 1910). the lengthening of the isosismal lines in ne-sw direction of the near field of earthquakes with origin in the straits is consistent with the analysis of focal mechanism and the geostructural framework of this area (bottari et al., 1984). the most recent earthquakes (4.0 ≤ m ≤ 4.7), which occurred between 1975 and 1995, with hypocentral depth encompassed between 8 and 21 km, show either normal or strike-slip focal mechanism along the ne-sw direction and in some case along e-w direction (caccamo et al., 1996: neri et al., 1996; frepoli & amato, 2000). therefore, analysis of intensity distributions and focal mechanisms of earthquakes originating in the area of the straits shows the actual seismogenetic activity of faults of the ne-sw structural system but also of tectonic structures with e-w trend. a. bottari, c. bottari & p. carveni 117 5. the salt marshes 5.1 pantano piccolo pantano piccolo is the deepest natural basin of sicily. it presents an almost rectangular shape with the major diagonal oriented in a nw-se direction where it reaches a length of about 650 m (fig. 3). the bathymetric trend of this marsh is asymmetrical, as noted also by abbruzzese & genovese (1952): starting from the western shore, the depth increases very little and gradually from 0 until some meters at a distance of 250 m from the coast; the maximum depth m = -28 m is found in the central eastern area of the basin (fig. 3). the same authors put forward the hypothesis that the genesis of the basin was tectonic, due to the collapse of its base. the basin, placed inside the northern sector of the coastal plain is bounded to w by a nw-se normal fault, with a ne dipping (fig. 1: h) and to e by two small ne-sw normal faults which lower to nw (fig. 1: i, l). these faults were pointed out through seismic surveys (del ben, 1985). to north the basin of the small marsh is separated from the tyrrhenian sea from a strip of beach deposits, primarily gravel-sandy, 150 m wide. the width of the actual beach is of around 70-80 m and the corresponding back beach is characterized by low elevation that locally do not reach 1 m above sea level. for the protection of such places from the west sea storms in different times banks in masonry and more recently in relief of gravels and sands were realized. the bathymetric gradient of the tyrrhenian sea overlooking the northern shore of the small marsh is 3-4 times smaller of that in relief in the lake basin: the bathymetric line of -10 m, that in the tyrrhenian sea is located at around 200 m from the coastline, in the small marsh is placed at around 55 m from the northern shore; the maximum depth m = -28 m, that in the basin it is located at around 240 m from the northern shore, in the sea it usually is located at around 600 m by the line of coast. toward the end of the 18th century, the small marsh and the ionian sea were connected through the construction of a channel (fig. 2: c1) ; in 1962 it was also connected to the tyrrhenian sea (fig. 2: c2). both the digging works were realized for favouring the development of the harvest of mussels. the northern coast of peloro cape peninsula, from acquarone to the mortelle beach, is modelled by a normal fault (fig. 1: i), that lowers to north, that was mapped from jacobacci (1961), bonfiglio & violanti (1983) and del ben & finetti (1985). nevertheless the trend of bathymetric lines overlooking the northern coastal lowland seems us compatible with his prolongation to east to peloro cape. the strong asymmetry of the marsh bathymetry, the steep slope of the northern and eastern shores and the maximum depth value, which is the greatest of all natural basins of sicily, support the hypothesis of a tectonic genesis. 5.2 pantano grande pantano grande in ganzirri is a small and shallow coastal basin (surface, 0.34 km2, maximum depth, 6.5 m, 1.67 km long, and approximately 0.28 km wide, roughly rectangular in shape, with a rapport to the extension equal to 5.9) and its biggest sides run parallel to the coastline (figs. 2, 4). it is located to the north of ganzirri village, where the coastal plain is approximately 500 m wide and it is separated from the sea by a strip of holocene alluvium deposits formed by silt, sand and gravel (gargano, 1994) on which aeolian deposits outcrop (bonfiglio & violanti, 1983). as regard the genesis of the big marsh we should consider that for the development of a coastal lake we needed: (1) a submerged coastal zone and many inlets; (2) a very shallow sea; (3) fluvial mouths which provide remarkable amount of sands and/or gravels. in this condition, it is possible to get a coastal bar at a short distance from the coast, next to an inlet. the bar develops to a tombolo and the bay become a lagoon or a fig. 3 pantano piccolo salt marsh: above, map of the isobaths (continuous curve distance 5 m and dot curves distance 1 m, maximum depth m = 28 m); below, altimetric-bathymetric profiles along a-b and c-d shares (derived from abbruzzese & genovese, 1952). fig. 4 pantano grande salt marsh: above, map of the isobaths (continuous curve distance 1 m); below, altimetricbathymetric profile along m-n share. tectonic genesis of the salt ... 118 coastal pond. the general features of a coastal pond are: low shores and shallow depth and finally a lengthened shape parallel to the coastline. for such morphological characteristics of pantano grande basin, and particularly for the shallow depth of its waters could be preliminary supposed that it is a coastal basin (fig. 4). it could be formed by an amassing of sands and gravels which were carried away and after deposited by the sea currents and wave motion. however the other conditions are not satisfied. the straits of messina results to be uplifting (westaway, 1993), there are not inlets and there are not water-courses to convey enough amount of sands and gravels. besides the sea depth along the coasts increases sensibly with the distance from the seashore (figs. 1, 2). consequently a sedimentary genesis for the pantano grande cannot be proposed. concerning the sediments that form the submerged beach, colantoni (1987) reports a dimension encompassed between medium size sand and gravel. according to amore et al. (1988) the submerged beach is formed by sands whose medium size is 1.8÷2.0 mm, while the emerged beach is prevalently constitutes by sand. the portion of the coastal plain where is located pantano grande is interested from two faults with direction ene-wsw, partly already noticed by gargano (1994) and from lentini et al. (1998; 2000): in the maps of these authors the faults, that are here indicated with the letter a and b, are interrupted at 2 km to wsw from the pantano grande (fig. 1). del ben (1985) and del ben & finetti (1985) noticed, through investigations of high-resolution seismic surveys, that on prolongation of fault b there is a direct fault, with rejection of around 10 m and a lower southern block (fig. 1: g). this fault, that is located to some tens of meters upstream of the northern shore of the pantano grande (fig. 1), will be subsequently indicated as faglia di ganzirri. it was shown up during two seismic profiles denominated ms2 and ms7 (figs. 5, 6), and it extends to north till the small marsh. this fault displaces of about 10 m the refractor horizon “a” placed at the top of sub-weathering in the gravels and sands of the formazione di messina. in addition, the same authors have revealed that some small normal faults nw dipping model the southern shore of the salt marsh (fig. 1: d, e, f); some direct faults on the prolongation of fault a, approximately parallel to the coastline, fault downward the straits (fig. 1). the basin is transversally bound by the extension of two direct faults, parallel to each other, and which make up part of an ene–wsw oriented system (lentini et al., 1998). the same authors indicated that a doubtful fault (fig. 1: c), with the same direction, which was located adjacently to the greatest axis of pantano grande. gargano (1994) reported the same faults (a and b), but did not recognize any fault along the pantano grande basin. as observed, and together with an analysis of the geomorphological characteristics of the peloro cape area, the coastal plain is bounded by two direct fault plans ene–wsw oriented. the first one (fig. 1: g) is situated along the nw shore of the pantano grande, fig. 5 sm-2 seismic high resolution profile along c-d share (fig. 1): a) diagram of the intercept-times; b) seismic section (after del ben & finetti, 1985). a. bottari, c. bottari & p. carveni above the mentioned holocene deposits and in contact with the underlying mid-pleistocene formazione di messina. this fault plan is not visible anymore due to the intense urbanisation experienced by the site, to the scarce mechanical characteristics of the formations and to the existence of a colluvium covering. the second fault, on an extension of a, situated to the south of the southern shore of the basin and parallel to b, conforms the coastline between the outlet of the guardia river and peloro cape (fig. 1: a’). 5. new data and surveys summarizing, the results of the morphological characteristics, tectonic elements and seismic surveys mentioned above, indicate that the ionian coastal plain is bound by two direct faults, parallel to each other and ene–wsw oriented, with the edge that lowers towards the sse. the basin of pantano grande is situated inside such a step: the northernmost of the two faults conforms the northern shore of pantano grande, while the southern shore is conformed by some small faults (del ben, 1985) which lower towards nw (fig. 1, d, e and f). a wide substratum of sterile conglomerate beneath sea level (fig. 7) prevalently outcrops along the waterline between ganzirri and faro; it has been mapped during an underwater survey. the outcrop (fig. 8) bound a strip of beach 2.3 km long, from pantano grande to punta sottile. the average width of the outcrop measures approximately 20 m, with a maximum values around 35 m and thickness up to 3 m. such a value is greater than that already ascertained from boreholes drilled to the ne, near punta sottile (fig. 2: s1), where intercalations of coarse pebble conglomerate present a thickness of about 50 cm which were found within the sand and gravel deposits (bonfiglio & violanti, 1983). according to the same authors this deposit is a beach rock. conversely, this conglomerate is missing in a layer 30 m thick, formed by medium size sand and grey polygenetic gravels with lens of mud in the upper part, investigated during geognostic boring carried out 300 m to west of la torretta (servizi tecnici s.p.a. fintecna gruppo iri, 1999; fig. 9). with its squashed funnel shape, pantano piccolo presents a bathymetric trend that can be justified by assuming that the basin was formed by a tectonic pro119 fig. 6 sm-7 seismic high resolution profile along e-f share (fig. 1): a) diagram of the intercept-times; b) seismic section (after del ben & finetti, 1985). fig. 7 particular of the mid-pleistocene sterile pebble conglomerate outcropping along ganzirri shoreline. tectonic genesis of the salt ... cess connected with the activity of the faults that conform to the peloro cape peninsula. the strong acclivity of the bottom along an e-w direction near the centre of the basin corresponds to a direct fault oriented approximately nnw–sse, that lowers towards ene and was reported by del ben (1985) and d el b en & f inetti (1985). samples taken from the marsh bottom next to bathymetric line of – 5m, on the edge of the scarp that bounds the southwestern sector of the basin, show that they were formed by conglomerate presumably belonging to the formazione di messina. as a whole, the data from literature and the results of various tests carried out in the study area allow to define the geological section of the area of study (fig. 10). the direct fault along the northern shore of pantano grande (fig.1: g) is supported by the previously mentioned geophysical surveys such as the small faults (fig. 1: d, e and f) which bound it to the south, and are compatible with the evidence of local subsidence derived from historiographical documentation; the existence of the fault which conforms to the coastline (fig. 1: a’) is supported by the morphological analysis and the results of geophysical exploration (del ben, 1985). 6. conclusive suggestions the observation reveal that the genesis of the pantano piccolo and pantano grande basins is markedly tectonic, as supported by the following points: a) the hilly relief located upstream of pantano grande, makes up a small horst bound by faults ene–wsw oriented; the northern fault constitutes the limit of the mortelle coastal plain on the tyrrhenian sea slope (fig. 1: i); the less evident southern fault (faglia di ganzirri; fig. 1: g) delimits the northern shore of pantano grande. the lengthened shape of the basin 120 fig. 8 map of the mid-pleistocene sterile pebble conglomerate outcropping along ganzirri shoreline (above) and ganzirri-punta sottile shoreline (below). fig. 9 shallow stratigraphy resulting from geognostic boring 300 m at w of la torretta (d2 , in fig. 2). a. bottari, c. bottari & p. carveni parallel to ganzirri fault direction and the contiguous location of this fault with the basin are substantial elements which configure the causal nexus about the tectonic genesis of pantano grande. besides, with reference to the remains of ancient temple uncovered at a few meters depth during the digging work of a canal between pantano piccolo and pantano grande and of present-day molluscs of brackish environment brought to light during well borings in margi, show that level was correspondent to the bottom of one or more ancient small marshes which at the present-day are not anymore existing. such evidence are to be related to local subsidence processes activated by movement of the direct fault of ganzirri; (b) the transversal dimension of pantano grande is bound to the north by the above mentioned g fault and to the south by some small direct faults which lower towards the nnw (fig. 1: d, e, f); another normal fault ene–wsw oriented, and which lowers towards the sse, model the ionian coastline from the outlet of the guardia river to peloro cape (fig. 1: a’); c) the basin of pantano piccolo, located in the northern coastal plain, is characterised by a conspicuous depth compared to its horizontal dimensions, by a marked asymmetry of the isobaths and by a steep slope acclivity of northern and eastern shores. in the eastern sector of the basin, where the depth reaches the maximum value, the bathymetric trend along the we profile suffers a rough increase and the depth by an initial value of -1.5 reaches -28 m. in this portion the bathymetric trend is three times of that observed along the tyrrhenian shore. the basin is located in a semigraben, formed by a direct fault nw-se oriented and ne dipping (fig.1: h) and by two direct small faults nesw oriented and nw dipping (fig. 1: i, l ). in conclusion, the analysis of geomorphological features of pantano piccolo correlated to those of the area in which the salt marsh is placed is consistent with a tectonic genesis. acknowledgments this work was financially supported by pra 2003 ateneo di messina (a. bottari) and m.i.u.r. in the framework of morpho-dynamics of seismically active coastal zone (p. carveni). references abbruzzese d. & genovese s. 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(1980) indagine geologicopetrografica sul cristallino dell’aspromonte centro settentrionale (calabria). boll. soc. geol. it., 99, 255-268. sauret b. (1980) contribution à l’étude néotectonique du détroit de messine (italie, sectur de reggio calabria). thése 3me cycle, univ. paris, vii, 1258. selli r. (1978) geologia e sismotettonica dello stretto di messina. convegno su: l’attraversamento dello stretto di messina e la sua fattibilità, 4-6 luglio 1978. att. acc. naz. lincei, 43, 119-154. servizi tecnici s.p.a. fintecna gruppo iri (1999) perizia di variante e suppletiva al progetto (n° l16) per la realizzazione della stazione media di messina ganzirri: relazione geologica. ministero del ll.pp, roma, 17 p. valensise g. & pantosti d. (1992) a 125 kyr-long geological record of seismic source repeatability: the messina straits (southern italy) and the 1908 earthquake (ms 71/2). terra nova, 4, 472-483. westaway r. (1993) quaternary uplift of southern italy. j.g.r., 98, 21741-21772. 122 ms. ricevuto il 1° febbraio 2005 testo definitivo ricevuto il 2 settembre 2005 ms. received: february 1, 2005 final text received: september 2, 2005. a. bottari, c. bottari & p. carveni imp.forno_boano riorganizzazione del reticolato idrografico nella collina di torino in relazione alla deformazione quaternaria (nw italy) maria gabriella forno1 & paola boano2 1 dipartimento di scienze della terra, università di torino 2 libero professionista, via asti 13 tonco (at) riassunto: forno m. g. & boano p., riorganizzazione del reticolato idrografico nella collina di torino in relazione alla deformazione quaternaria. (it issn 0394-3356, 2007). il reticolato idrografico, essendo strettamente condizionato dalla direzione di massima pendenza della superficie topografica su cui si sviluppa, risulta un indicatore molto attendibile delle variazioni nell’inclinazione di un determinato settore e di conseguenza può diventare un marker estremamente significativo e sensibile della deformazione recente. nel versante meridionale della collina di torino si osservano numerosi esempi di riorganizzazione di tratti del reticolato idrografico indotti o favoriti dall’evoluzione quaternaria della struttura anticlinale. negli esempi presi in considerazione le modalità di adattamento del reticolato idrografico sono strettamente condizionate dal grado di incisione dei corsi d’acqua, a loro volta connesso con l’entità della deformazione. in particolare in corrispondenza all’asse della sinclinale dell’altopiano di poirino è avvenuta una modestissima variazione di inclinazione indotta dalla deformazione recente: in questi settori il reticolato idrografico, poco inciso entro alla pianura alluvionale, ha potuto adattarsi perfettamente al mutare della superficie topografica, abbandonando le tracce precedenti. e’avvenuta in questo modo una inversione del drenaggio: il corso d’acqua principale, che prima defluiva verso e, ora scorre verso w. lungo i fianchi della struttura anticlinale collinare, è avvenuto invece un più rilevante aumento di inclinazione indotto dalla deformazione recente: in questi settori il reticolato conserva testimonianza degli antichi andamenti che vengono progressivamente catturati dal reticolato idrografico attuale. infine nelle aree prossime all’asse dell’anticlinale si è verificato un sensibile aumento di inclinazione indotto dalla deformazione: in queste aree i corsi d’acqua, vincolati all’andamento precedente, non subiscono variazioni di tracciato in pianta ma rispondono con un approfondimento del tratto inferiore per adattarsi al nuovo gradiente. abstract: forno m. g. & boano p., re-organization of hydrographic network in the torino hill connected to quaternary deformation. (it issn 0394-3356, 2007). the hydrographic network, remarkably conditioned by the gradient of the topographic surface, is a very reliable marker of the morphological modifications of an area. it can consequently become a significant and sensible marker of the recent deformation. numerous examples of re-organization of hydrographic network are pointed out in the southern slope of the torino hill: they are induced or favoured by the quaternary evolution of the anticline. in the considered examples the possibility of the adaptation of hydrographic network is conditioned by the watercourses incision degree, connected with the incidence of the deformation. near the syncline axis of the poirino plateau a very weak gradient variation occurred, connected to the recent deformation: in this area the scarcely entrenched hydrographic network is sensible to the gradient variation, and the previous valleys may be left. an inversion of the drainage can therefore occur: the main watercourse, before flowing to the east, now flows to the west. in the sides of the anticline structure of the torino hill a remarkable increase of the inclination took place, connected to the recent deformation: in this area the hydrographic network preserves the evidence of ancient trends, cut progressively by the present network. near the anticline axis a very strong increase of the gradient finally occurred, connected to the recent deformation: in this area the watercourses, entrenched in the previous trends, are not subject to direction variations; on the contrary they are subject to deepening of the lower stretch because of the new gradient. parole chiave: collina di torino, reticolato idrografico, deformazione, pleistocene. keywords: : torino hill, hydrographic network, deformation, pleistocene. il quaternario italian journal of quaternary sciences 19(2), 2006 215-222 1. introduzione gli esempi di riorganizzazione del reticolato idrografico segnalati in questa nota, osservati in occasione dei rilevamenti effettuati per la realizzazione del foglio geologico alla scala 1:50.000 "torino est” nell’ambito del progetto carg, riguardano il versante meridionale della collina di torino al raccordo l’altopiano di poirino (fig. 1). nella collina di torino la successione marina terziaria appare deformata a costituire una struttura anticlinale asimmetrica con asse sw-ne in continuità, verso sud, con la sinclinale dell’altopiano di poirino (bortolami et al., 1969; forno, 1982): l’anticlinale appare delimitata verso nw dal “thrust padano” sepolto, che ne determina la sovrapposizione sui termini più recenti della pianura padana, e verso e dall’importante “fascia di deformazione di rio freddo”, al limite con la struttura complessa dei rilievi del monferrato (piana & polino, 1994; festa et al., 2005). tra le novità emerse negli ultimi anni e confermate dai recenti rilevamenti, la più significativa è rappresentata dal riconoscimento della sensibile deformazione recente della struttura anticlinale, per la quale sono stati ipotizzati valori medi di sollevamento per l’intero pleistocene medio e superiore con ordine di grandezza di 1 mm/anno (boano et al., 2004). tale ricostruzione è desunta dalla presenza nell’area collinare delle tracce di antichi corsi d’acqua, non riferibili al reticolato idrografico collinare ed invece da collegare con il reticolato idro218 m.g. forno & p. boano grafico alpino, che risultano sensibilmente deformate e inglobate nel rilievo. le tracce conservate nel versante meridionale della collina di torino e nell’altopiano di poirino, blandamente deformate, sono da collegare ad un antico percorso del fiume po (a in fig. 1), riferibile al pleistocene medio-superiore, prima dell’impostazione dell’attuale corso d’acqua a nord del rilievo: questo antico collettore subiva nel tempo una progressiva migrazione verso sud (forno, 1980; forno, 1982; compagnoni & forno, 1992). le testimonianze conservate nei versanti occidentale e nordoccidentale, sensibilmente deformate e terrazzate, sono invece da collegare ad antichi percorsi dei fiumi dora riparia e stura di lanzo (b in fig. 1), riferibili anch’essi complessivamente al pleistocene medio-superiore, caratterizzati invece da una migrazione verso nw (boano et al., 2004; forno & lucchesi, 2005). le ipotesi circa la deformazione recente della struttura collinare sono in accordo con i dati desunti dai rilievi geodetici di precisione relativi al primo sessantennio del 1900, che indicano un sollevamento con valori fino a 3,5 mm/anno (arca & beretta, 1984): nel dettaglio il sollevamento risulta sensibilmente asimmetrico, con tassi maggiori per il versante settentrionale, in prossimità dei thrusts sepolti che delimitano il rilievo, e invece più modesti per quello meridionale, in continuità con l’altopiano di poirino. 2. assetto dell’attuale reticolato idrografico del t. banna nel versante meridionale della collina di torino e nell’altopiano di poirino si sviluppa l’attuale reticolato idrografico del t. banna, caratterizzato da un corso d’acqua principale con drenaggio verso w e da due opposti sistemi di affluenti drenanti mediamente verso s e ssw, per gli affluenti di destra, e verso nnw, per quelli di sinistra (fig. 2). i rilevamenti nell’ambito del progetto carg fig. 1sul versante meridionale della collina di torino e nell’altopiano di poirino sono conservate le tracce di antichi andamenti del paleopo (a); sul versante settentrionale sono invece conservate le testimonianze di antichi andamenti dei fiumi dora riparia e stura di lanzo (b). the relics of ancient trends of the paleopo (a) are preserved in the southern slope of the torino hill; the relics of ancient trends of the dora riparia and the stura di lanzo rivers (b) are preserved in the northern slope. fig. 2 il reticolato del t. banna è costituito da un’asta principale drenante verso w (a) e da due opposti sistemi di affluenti drenanti verso ssw, quelli di destra (b), e verso nnw, quelli di sinistra (c); asse dell’anticlinale della collina di torino (d); asse della sinclinale dell’altopiano di poirino (e). le frecce indicano il progressivo tilting dell’area. the hydrographic network of the banna stream is formed by a main watercourse draining toward w (a) and by two opposite tributaries draining toward ssw (b) and nnw (c), respectively; anticline axis of the torino hill (d); syncline axis of the poirino plateau (e). the arrows show the progressive tilting. fig. 3 sono osservabili relitti di valli con drenaggio verso e riferibili al paleopo, relitti con drenaggio verso se riferibili agli affluenti del paleopo, l’attuale t. banna con drenaggio verso w e gli attuali affluenti con drenaggio verso s o ssw. valleys of the paleopo draining toward e, valleys of the tributaries of paleopo draining toward se, t. banna draining toward w and present tributaries draining toward s or ssw are observed. 219riorganizzazione del reticolato idrografico ... hanno consentito di ricostruire con estremo dettaglio la successione stratigrafica del settore attualmente drenato dall’asta principale e dagli affluenti di destra e di riconoscere in queste aree relitti di valli fluviali caratterizzate da andamenti diversi rispetto alle incisioni attuali (fig. 3): come si vedrà più dettagliatamente in seguito questi relitti sono indicativi di antiche direttrici di drenaggio rispettivamente verso e (paleopo) e verso se (affluenti del paleopo), che contrastano con il deflusso attuale verso w dell’asta principale e verso ssw del sistema affluente. dal punto di vista altimetrico i relitti con diverso andamento sono conservati a quota diversa che rispecchia la loro differente età di impostazione, suggerita anche dal grado di alterazione non confrontabile dei depositi ad essi associati (cfr. figg. 6 e 8): le tracce del paleopo sono distribuite sulla sommità delle dorsali (1 in fig. 4) a costituire un’antica pianura alluvionale, ora profondamente dissecata; le tracce degli affluenti del paleopo sono conservate ad una quota intermedia a costituire valli sospese (2 in fig. 4) rispetto alle incisioni attuali, che appaiono invece notevolmente più profonde (3 in fig 4). i relitti idrografici più antichi (1 in fig. 4), già noti in letteratura, sono testimoniati dalla presenza in corrispondenza alla sommità delle attuali dorsali di depressioni allungate, arcuate in pianta, con raggio di curvatura chilometrico e varia orientazione, prevalentemente abbandonate (forno, 1982; compagnoni & forno, 1992). queste depressioni sono caratterizzate da ampiezza notevole, di alcune centinaia di metri, profondità tra alcuni metri e alcune decine di metri e risultano parzialmente colmate da corpi lenticolari relativamente estesi costituiti da sedimenti fluviali ghiaiosi e siltosi (fig. 5): i depositi ghiaiosi, con stratificazione incrociata concava, affiorano localmente alla base dei corpi fluviali; al di sopra si osservano più continui depositi siltosi, con fig. 4 le evidenze dell’antico collettore a meandri sono conservate sulle sommità delle dorsali (1); le tracce dei corsi d’acqua affluenti del collettore a meandri (2) costituiscono valli sospese rispetto alle incisioni attuali (3). the relics of meander collector ancient trends are preserved on the hilly ridges (1); the relics of meander watercourse tributaries (2) are suspended valleys on the present valleys (3). fig. 5 depositi siltosi e ghiaiosi connessi con il paleopo drenante verso e (pleistocene medio) (1); depositi fluviali sabbioso-ghiaiosi connessi con gli affluenti del paleopo (a) drenanti verso se (pleistocene superiore) (2); depositi eterogenei legati agli attuali corsi d’acqua (b) drenanti verso s e ssw (olocene) (3). silt and gravel sediments of the paleopo draining toward e (middle pleistocene) (1); sand-gravel sediments of the tributaries of the paleopo (a) draining toward se (upper pleistocene) (2); heterogeneous sediments of the present watercourses ( ) draining toward s and ssw (3)(holocene). fig. 6 i depositi fluviali ghiaiosi (b) e siltosi (c) connessi con il paleopo riferibili al pleistocene medio colmano ampie depressioni modellate nella successione marina terziaria (a). fluvial gravel (b) and silt (c) sediments of the paleopo, referred to middle pleistocene, fill wide depressions modelled in the cenozoic marine sediments (a). 220 spessore di alcuni metri, privi di stratificazione. la notevole pedogenesi dei sedimenti fluviali, evidenziata dal colore bruno-rossastro e dalla presenza di clasti molto alterati, suggerisce il riferimento al pleistocene medio (arduino et al., 1984) (fig. 6): in accordo con questa attribuzione cronologica è la presenza di una copertura di loess eolico di età pleistocenica superiore. mentre l’espressione morfologica di queste depressioni risulta spesso molto attenuata dalla presenza dei corpi fluviali e dell’ulteriore copertura di sedimenti eolici e\o colluviali, la distribuzione dei depositi fluviali descritti, esclusivamente associati alle depressioni relitte, risulta invece estremamente significativa. circa la genesi di questi elementi morfologici un insieme di considerazione permette di escludere che siano forme “attuali”da collegare all’attuale reticolato idrografico. le osservazioni più significative a questo proposito sono, oltre alla copertura di loess eolico, la distribuzione delle depressioni allungate, conservate in modo discontinuo sulla sommità delle dorsali collinari, l’assenza di un reticolato idrografico superficiale, le dimensioni rilevanti, con raggio di curvatura chilometrico, l’andamento variabile in pianta con prevalenza dell’orientazione e-w, circa ortogonale ai tracciati del reticolato idrografico attuale. l’insieme di questi elementi suggerisce invece che le forme descritte corrispondano ai relitti di antiche ampie valli fluviali, a costituire un’antica pianura alluvionale, ora profondamente dissecata (1 in fig. 5). la distribuzione dei depositi fluviali, che come si è detto colmano parzialmente depressioni con andamento ad anello sviluppate attorno a rilievi modellati nel substrato, indicano in particolare il legame con un corso d’acqua a meandri debolmente incastrati con raggio di curvatura chilometrico: la direzione prevalente delle fasce meandriche è in accordo con una direzione media di flusso circa e-w; la presenza di più fasce meandriche suggerisce che questo corso d’acqua fosse interessato da una progressiva migrazione verso sud traslando dall’attuale versante meridionale della collina di torino verso l’altopiano di poirino. la litologia dei clasti dei sedimenti fluviali ghiaiosi suggerisce che si trattasse di un percorso del “paleopo”, sviluppato a sud della collina di torino (fig. 3), drenante parte del settore alpino occidentale (compagnoni & forno, 1992). i relitti idrografici successivi (2 in fig. 4), riconosciuti invece in occasione dei recenti rilevamenti, corrispondono a evidenti segmenti di valli con andamento per lo più rettilineo in pianta e direzione di drenaggio in media verso se, anch’esse prevalentemente abbandonate (fig. 7) : sono sviluppati entro i solchi vallivi attuali, a quota sensibilmente inferiore rispetto ai relitti precedenti. questi relitti, con larghezza fino al centinaio di metri e incisione di alcune decine di metri, sono anch’essi parzialmente colmati da corpi lenticolari allungati costituiti da sedimenti fluviali sabbioso-ghiaiosi, con una più o meno evidente stratificazione incrociata concava. un insieme di elementi permette di escludere, anche in questo caso, che siano forme “attuali”: appaiono variamente sospesi e mostrano andamenti differenti in pianta rispetto ai tracciati attuali, dai quali risultano ripetutamente troncate; la modesta pedogenesi dei sedimenti fluviali, evidenziata dal colore bruno e dalla presenza di clasti poco alterati, suggerisce il riferimento al pleistocene superiore (arduino et al., 1984) (fig. 8). l’insieme di queste evidenze consente di ipotizzarne il riferimento a precedenti corsi d’acqua: l’andamento verso se suggerisce in particolare di riferirli ad affluenti del paleopo, impostati contemporaneamente alla progressiva migrazione verso sud di questo collettore (2 in fig. 5) (carraro et al., 2005). i tratti idrografici attuali, corrispondenti all’asta principale del t. banna drenante verso w e ai corsi d’acqua affluenti di destra con drenaggio verso s e ssw (3 in fig 4), modellano infine le incisioni più accentuate, con larghezza in genere di alcune decine di metri e profondità fino ad un centinaio di metri. come si vedrà meglio in seguito solo questi ultimi tratti mostrano andamento congruente con l’attuale inclinazione dell’area, in media verso sw (fig. 3). agli attuali corsi d’acqua impostati nei fondovalle sono infine da collegare i depositi fluviali recenti (3 in fig. 5), caratterizzati da natura molto eterogenea. fig. 8 depositi fluviali sabbioso-ghiaioso connessi con gli affluenti drenanti verso se riferibili al pleistocene superiore. fluvial sand-gravel sediments of tributaries draining toward se related to the upper pleistocene. fig. 7 ampia valle di un precedente percorso del r. ambuschetto drenante verso se, priva di reticolato idrografico superficiale. wide valley of r. ambuschetto ancient se trend, without superficial network . m.g. forno & p. boano 221 i diversi andamenti idrografici presi in considerazione sono indicativi di una diversa configurazione della superficie topografica indotta dalla deformazione recente: le tracce del paleopo drenante verso e, conservate come depressioni sulle dorsali, sono connesse con una pianura a meandri caratterizzata da una debolissima inclinazione verso e; la progressiva migrazione del paleopo verso s e l’impostazione degli affluenti, conservati come valli sospese drenanti verso se, indicano che si realizzava progressivamente una inclinazione verso s connessa con la deformazione differenziale dell’anticlinale (indicata dalla freccia nera in fig. 2). lo sviluppo del t. banna drenante verso w e degli attuali affluenti drenanti verso s e ssw indica che la superficie assumeva l’attuale inclinazione, rispettivamente verso w nel settore di altopiano e verso ssw nel settore collinare, connessa con un tilting del margine orientale (indicata dalla freccia in fig. 2) (forno, 1982). 3. fenomeni di riorganizzazione del reticolato idrografico i fenomeni di adattamento del reticolato idrografico alla progressiva realizzazione dell’inclinazione attuale verso sw dell’area sono avvenuti con modalità differenti, a seconda dell’entità dell’approfondimento dei corsi d’acqua nei diversi settori dell’area. nel settore meno deformato, in corrispondenza all’asse della sinclinale, i relitti del paleopo risultavano incisi di pochi metri entro alla pianura alluvionale: la scarsa incisione ha fatto sì che il t. banna, impostatosi a seguito della diversione dell’antico collettore, abbia potuto migrare lateralmente per adattarsi al mutare della superficie topografica, cancellando le tracce del precedente corso d’acqua. la variazione di pendenza che si può ipotizzare essersi realizzata tra quella originaria, molto debole verso e, e quella attuale conseguente al tilting, debolissima verso w, è stata modesta: in questo caso ad una minima variazione di pendenza indotta dalla deformazione è corrisposta una radicale modifica nell’andamento del reticolato idrografico, con inversione del drenaggio, che ha quindi enfatizzato la variazione morfologica. spostandoci verso n nei settori mediamente deformati lungo i fianchi dell’anticlinale il paleopo e la rete affluente erano incisi fino ad alcune decine di metri entro alla pianura alluvionale: in questo caso i corsi d’acqua impostatisi a seguito del tilting verso s, pur adattandosi alla variazione nell’andamento della superficie topografica, conservano testimonianza degli antichi andamenti. sono osservabili in particolare i relitti del collettore principale e dei suoi affluenti: si può ipotizzare che contemporaneamente alla migrazione verso s fig. 10 variazioni nell’andamento in pianta del rivo dei molini: le valli abbandonate successivamente (a1, a2, a3 e a4) sono delimitate da scarpate con altezza progressivamente decrescente rispetto alla valle attuale. legenda come in fig.5. trend variations of rivo dei molini stream: the abandoned valleys (a1, a2, a3 and a4) are separated by decreasing scarps from the present valley. legend as in fig. 5. fig. 9 variazioni negli andamenti in pianta del rio ambuschetto (a1, a2, a3, a4 e a5) progressivamente più prossimi alle direttrici attuali. legenda come in fig. 5. trend variations of ambuschetto stream (a1, a2, a3, a4 and a5) as they progressively reach the present trend. legend as in fig. 5. riorganizzazione del reticolato idrografico ... 222 del paleopo, drenante verso e, nei settori progressivamente abbandonati dal collettore principale, si siano impostati i corsi d’acqua drenanti verso se, ancora affluenti del paleopo, ora conservati come ampie valli (fig. 7) sospese rispetto agli attuali fondovalle. nel dettaglio la maggior parte dei segmenti modellati dall’antico reticolato, principale e affluente, risulta abbandonata e conservata come valli relitte, in quanto non congruente con l’attuale inclinazione dei versanti; solo localmente alcuni segmenti, orientati invece casualmente secondo la direzione di pendenza attuale, appaiono riutilizzati dagli attuali corsi d’acqua, affluenti del t. banna, che come si è detto drenano prevalentemente verso ssw (fig. 5). le valli relitte non riutilizzate, prive di un reticolato idrografico superficiale, appaiono troncate a monte dall’incisione degli attuali corsi d’acqua. le stesse valli, anche se prive della testata, raccolgono ovviamente le acque ruscellanti e appaiono comunque reincise nel tratto inferiore: nel fondovalle si sviluppano talvolta emergenze idriche, caratterizzate da portate notevoli, sviluppate al limite tra il settore superiore, abbandonato, e quello inferiore, reinciso. analizzando come è avvenuto il passaggio tra gli andamenti verso se del reticolato affluente del paleopo a quelli attuali verso ssw si osserva un ripetuto adattamento dei corsi d’acqua alla progressiva variazione nell’inclinazione della superficie topografica indotta dalla deformazione (fig. 9). in questi settori ad una variazione di inclinazione di pochi gradi è corrisposta una evidente variazione dei tracciati fluviali. l’insieme delle valli abbandonate conservate non indica variazioni casuali di un singolo canale ma una riorganizzazione sistematica che riguarda la maggior parte dei corsi d’acqua: le valli abbandonate progressivamente più recenti sono distribuite a quota via via inferiore e delimitate da scarpate con altezza progressivamente decrescente rispetto alla valle attuale (fig. 10). localmente le variazioni nell’andamento del reticolato idrografico creano rilievi isolati come quello su cui è edificata la parte più elevata del centro storico di chieri, che comprende la chiesa di san giorgio, interpretabile come lembo relitto di un terrazzo fluviale (fig. 11): inizialmente si avevano due corsi d’acqua circa paralleli drenanti verso se, interrotti dall’andamento verso s dei tratti attuali del reticolato idrografico (fig. 12). nelle aree più deformate prossime all’asse della struttura anticlinale il collettore principale e il reticolato affluente erano notevolmente più incisi entro alla pianura alluvionale: la marcata incisione ha reso impossibili le variazioni nell’andamento in pianta da parte degli attuali corsi d’acqua e di conseguenza non è fig. 11 lembo di terrazzo di san giorgio connesso con l’incisione di un terrazzo fluviale del rio dei ceppi (a) da parte dell’attuale reticolato idrografico (b). san giorgio relic connected with the incision of rio dei ceppi fluvial terrace (a) by the present hydrographic network (b). fig. 12 lembo di terrazzo fluviale su cui è edificato il centro storico di chieri, modellato da un antico andamento verso se del rio dei ceppi, interrotto dall’andamento attuale dei corsi d’acqua. the fluvial terraced surface on which the historical centre of chieri is built modelled by an ancient rio dei ceppi trend draining toward se, cut by the present network . avvenuta una evidente riorganizzazione del reticolato idrografico. le tracce del paleopo e dei suoi affluenti corrispondono a valli con profilo longitudinale caratterizzato da inclinazione variabile per la presenza di un tratto di testata poco inclinato: questi relitti, variamente troncati o approfonditi dal reticolato idrografico attuale, sono in genere riconoscibili per la presenza di selle in contropendenza nello spartiacque collinare (fig. 13). in questi settori i corsi d’acqua, vincolati all’andamento precedente, non subiscono variazioni di andamento in pianta ma rispondono con un approfondimento del tratto inferiore, per adattarsi al nuovo gradiente indotto dalla deformazione. m.g. forno & p. boano 4. conclusioni gli esempi segnalati confermano che il reticolato idrografico è un indicatore molto attendibile delle variazioni nell’inclinazione di un determinato settore; di conseguenza l’andamento dei corsi d’acqua può diventare un marker estremamente significativo delle variazioni nell’assetto della superficie topografica indotte dalla deformazione recente. gli stessi esempi confermano che il reticolato è un marker molto sensibile in quanto registra anche variazioni minime. una variazione nell’andamento dei tracciati idrografici è tanto più realizzabile quanto meno i corsi d’acqua sono approfonditi all’interno della pianura o del fondovalle alluvionale. in particolare nei casi di scarso approfondimento può verificarsi una totale riorganizzazione del drenaggio che porta all’obliterazione dei tracciati precedenti. nei casi di approfondimento intermedio i tracciati precedenti verranno invece abbandonati ma rimarranno conservati come valli relitte. nei casi infine in cui l’approfondimento dei corsi d’acqua è notevole il tracciato antico è vincolante e può avvenire solo una variazione nell’entità dell’approfondimento. bibliografia arca s. & beretta g. (1985) prima sintesi geodeticageologica sui movimenti verticali del suolo nell’italia settentrionale (1897-1957). boll. geod. sc. aff., 2, 125-156. arduino e., barberis e., carraro f. & forno m. g. (1984) estimating relative ages from ironoxide/total-iron ratios of soils in the western po valley, italy. geoderma, 33, 39-52, amsterdam. b o a n o p., f o r n o m. g. & l u c c h e s i s. (2004) pleistocene deformation of the collina di torino inferred from the modelling of their fluvial succession. il quaternario, it. journ. quatern. sc.,17 (2/1), 145-150. bortolami g.c., crema g. c., malaroda r., petrucci f., sacchi r., sturani c., tagliavini s. & venzo s. (1969) foglio 56 “torino” della carta geologica d’italia alla scala 1:1000.000. iia ed., serv. geol. it., roma. carraro f., forno m. g., giardino m. & paro l. (2005) field trip guide.14th meeting of the association of european geological societies, september 23th 2005, torino hill. il quaternario, it. journ. quat. sc., 18(2), 3-55. compagnoni r. & forno m. g. (1992) significato geologico di depositi fluviali ghiaiosi pleistocenici medi nella collina di torino. il quaternario, it. journ. quatern. sc., 5, 105-122. festa a., piana f., dela pierre f., malusà m., mosca p. & p o l i n o r. (2005) oligocene-neocene kinematic constraints in the retroforelan basin of the northwestern alps. rend. soc. geol. it, 2005, nuova serie. forno m. g. (1980) evidenza di un drenaggio abbandonato nel settore settentrionale dell’altopiano di poirino (prov. di torino). geogr. fis. dinam. quat., 3, 61-65. forno m. g. (1982) studio geologico dell’altopiano di poirino. geogr. fis. din. quat., 5, 129-162. forno m. g. & lucchesi s. (2005) la successione fluviale terrazzata pleistocenica dei versanti occidentale e nordoccidentale della collina di torino. il quaternario, it. journ. quatern. sc., 18(2), 123134. piana f. & polino r. (1994) la zona transpressiva di rio freddo e l’evoluzione convergente della collina di torino e del monferrato durante il terziario. atti tic. sc. terra, ser. spec., 1, 167180. 223 ms. ricevuto il 26 luglio 2006 testo definitivo ricevuto il 3 ottobre 2006 ms. received: july 26, 2006 final text received:october 3, 2006 fig. 13 la valle di rivalba, riconoscibile per la presenza di una evidente sella in contropendenza, appare decapitata e caratterizzata nella parte superiore da inclinazione modesta. the rivalba valley is cut and shows in the upper part a less inclined profile. riorganizzazione del reticolato idrografico ... imp.longhitano_zanini coastal models and beach types in ne sicily: how does coastal uplift influence beach morphology? sergio longhitano1, angiola zanini2 1 dipartimento di scienze geologiche, università degli studi della basilicata campus di macchia romana, 85100, potenza; e-mail: longhitano@unibas.it. 2 dipartimento di scienze geologiche, università degli studi di catania corso italia 55, 95100, catania; e-mail: zanini@unict.it. abstract: s. longhitano, a. zanini, coastal models and beach types in ne sicily: how does coastal uplift influence beach morphology? (it issn 0394-3356, 2005). this paper compares morphological and sedimentary characters of beach types occurring along the ionian coastline of ne sicily and local coastal uplift rates, with the aim of evaluating how vertical coastal movements influence beach morphologies. the ionian coastline of ne sicily may be divided into many coastal provinces and subprovinces, following the relative positions that each segment of littoral occupies within the general geological setting of the central mediterranean. this coastline runs perpendicularly along the africa-europe plate boundary, crossing successions belonging to the chain, volcanic products, a foredeep and a foreland sector. in this paper only the northern sector, pertaining to the chain and volcanic coastal provinces, is examined. from the south to the northern edge of ne sicily, four main localities were chosen for examination: (i) capo peloro/messina; (ii) taormina/giardini-naxos; (iii) riposto/praiola; (iv) ognina/catania. in these sites, a series of combined observations on the gradient of the nearshore profile, grain size of sediments, local water dynamics, and uplift rates identified classes of distinct beach types and models. results indicate that all these coastal profiles developed recently, due to vertical local tectonic movements rather than control by the width of the continental shelf, the morphology of which is strongly influenced by the malta escarpment fault system. differing coastal uplift rates define classes of beach types in which patterns of morphological and sedimentological characters, together with the hydrodynamics of the nearshore zone, are closely related to recent tectonic vertical movements of the coast. riassunto: s. longhitano, a. zanini, modelli costieri e tipi di spiaggia nella sicilia nord-orientale: come il sollevamento costiero influenza la morfologia della spiaggia? (it issn 0394-3356, 2005). la correlazione tra una serie di dati derivanti da uno studio di carattere morfologico e sedimentologico con i tassi di sollevamento calcolati lungo tutto il litorale ionico della sicilia nord-orientale ha permesso di identificare il grado di influenza che i movimenti verticali costieri possono avere sullo sviluppo dei differenti modelli di spiaggia. la costa orientale della sicilia può essere suddivisa in province e sotto-province costiere, in stretta relazione con le caratteristiche geologiche e geodinamiche che essa stessa presenta. il litorale percorre perpendicolarmente il margine di giunzione afro-europeo, attraversando, da nord verso sud, un dominio di catena, un dominio vulcanico, uno di avanfossa ed uno di avampaese. in questo lavoro vengono riportati i risultati che derivano dalle osservazioni condotte soltanto nel settore costiero di catena e vulcanico. da nord verso sud sono state considerate quattro principali località tipo: (i) capo peloro/messina, (ii) taormina/giardini-naxos, (iii) riposto/praiola e (iv) ognina/catania. in ognuna di queste località, sono state acquisite informazioni circa il gradiente del profilo sotto costa, il diametro medio dei sedimenti di spiaggia, le caratteristiche idrodinamiche locali e i valori relativi ai tassi di sollevamento dell’area costiera locale. la combinazione di questi parametri ha permesso di individuare distinte classi di differenti modelli di spiaggia. i risultati suggeriscono inoltre come la morfologia che caratterizza ognuno dei profili di spiaggia considerati è stata direttamente influenzata dall’azione dei movimenti di uplift costieri, piuttosto che dall’ampiezza della piattaforma continentale, che, tettonicamente controllata dal sistema di faglie della scarpata maltese, presente nel settore meridionale, si assottiglia progressivamente verso nord fino a scomparire del tutto. le differenti classi e modelli di spiaggia individuati per ciascun settore, mostrano pertanto altrettanto differenti sistemi di drenaggio a monte e caratteri morfo-sedimentologici che vengono direttamente controllati dai locali tassi di uplift. keywords: ne sicily; ionian coastline; coastal provinces; beach types; coastal uplift rate. parole chiave: sicilia nord-orientale; province costiere; modelli di spiaggia; tassi di sollevamento costiero. il quaternario italian journal of quaternary sciences 19(1), 2006 103-117 1. introduction the ionian coast of sicily (fig. 1) runs along the eastern part of the island, crossing an important geodynamic part of the central mediterranean. this littoral extends along terrains belonging to the africa-europe plate boundary, normal to the subduction direction (longhitano & zanini, 2005; 2006). in this geological setting, three structural coastal domains are identified: chain, foredeep and foreland. the three domains may be considered as a series of coastal compartments or provinces (sensu finkl, 2004), and include several examples of various beach types, each characterised by peculiar morpho-sedimentary features, in response to the geological setting within each segment of shoreline developed in recent times. the ionian coast of sicily has been studied in terms of its coastal dynamics and morpho-bathymetric features of the nearshore zone, sedimentary drift and budget, grain-size beach characteristics (amore et al., 1979; 1990), and meteomarine conditions (di geronimo, 1990; ferretti et al., 2003), disregarding the fundamen104 s. longhitano & a. zanini tal role of the coastal geological framework in the control of beach development. recent publications about coastal systems analyse the evolution of discriminated transects of different examples of shorelines from over the world in relation to recent tectonic evolution. in detail, quantification of uplift rates, fault control and relative morphological features of coastal environments identify separate geotectonic coastal provinces. recent anthropogenic influences are also included in the final evaluation of the coastal setting. this approach has been neglected in recent studies of the eastern coast of sicily, and this paper is a first preliminary approach on understanding of the coastline and its setting. this work describes and classifies some of the most representative beach types occurring along the northern segment of the ionian shoreline, using sedimentological, morphological and hydrodynamic datasets, in order to identify the various coastal provinces in relation to their respective geological settings and local uplift rates. 2. geological setting of ne sicily the north-eastern coast of sicily has a n-s (±30°) oriented shoreline, extending from capo peloro (north) and catania (south) (fig. 1). it faces the ionian sea and represents a microtidal oceanographic framework: here, only wave action and long-shore currents, controlled by the complex messina strait dynamics, influence coastal dynamics. the rivers outflowing on this coast are the main points of sedimentary input. they drain several areas, producing variable amounts of sediment, depending on lithology, gradient and headland altitude (which, in turn, controls the local rate of rainfall) of the respective drainage basins. from n to s, the zaffaria, d’agrò, letojanni, alcantara and macchia are the main rivers. the studied coastline is the northernmost geodynamic domain of the n-s geological transect (fig. 2). it lies above terrains representing the thin-skinned expression of a chain and the eastern flank of an active volcano, which, in turn, are counterparts of an extremely complex subduction zone running between the african plate (to the s) flexured beneath the european plate (from the n) (fig. 1, inset). 2.1 morphotectonics north-eastern sicily runs perpendicularly to the southern margin of the tyrrhenian basin, which includes calabria (gvirtzman & nur, 1999a,b). the study area consists of sedimentary and metamorphic rocks within a south-verging system of nappes of the appenine–maghrebian chain, overthrusting the northward-dipping african plate. the malta escarpment is the most important active tectonic structure influencing the evolution of the ne coast of sicily. it produces a dip-slip displacement, amounting to 3 km onshore. where it intersects the coast on the eastern side of mt etna, a series of active faults (the timpe fault system) occur, forming scarps of up to 200 m and fault planes displaying both dip-slip and right-oblique slip kinematic indicators (lanzafame et al., 1996; monaco et al., 1997). the orientation of the entire coastline within this domain is strongly controlled by the structural pattern fig. 1 ionian coast of sicily and geological setting (inset). many coastal provinces and subprovinces are identified, according to respective geological frameworks. the study sites mentioned in this paper are mainly located along the chain province, divided from n to s, into the peloritani mts and mt etna subprovinces. schema geologico generale della costa ionica della sicilia ed assetto strutturale (riquadro). il litorale può essere suddiviso in alcune province e sotto-province costiere in relazione al locale assetto geologico. il tratto costiero studiato per il presente lavoro interessa principalmente la provincia più settentrionale, ulteriormente divisa da n a s in peloritani mts subprovince e mt etna subprovince. of the faults dissecting the area. the most important structure intersecting the faults associated with the malta escarpment is the seismogenetic nne-sswstriking messina fault system which caused the messina earthquake (approximate magnitude 7.5) in 1908. this system defines the north-eastern coastline bordering the straits of messina and extends south to the taormina area. on strike, fault scarps also cut the surface of holocene deposits on the eastern side of mt etna, and are connected with the faults of the timpe system (lanzafame et al., 1996). the continental shelf flanking this coastal domain has a high gradient (3-4°) and a narrow seaward extension which progressively thins northwards (from 2.0 to 0.4 km). this complex structural setting has produced cliffed shorelines and promontories, and pocket, shingle and sandy beaches. each single type and its morphology also reflect the influence of lithology and uplift rate of the pertaining coastal province. 2.2 lithologic units the onshore lithologic units of the study area represent the southern flank of the calabrian-peloritani arc (amodio-morelli et al., 1976), formed of hercynian crystalline terranes, variously deformed according to a series of ese-verging thrust-sheet systems, and their cenozoic sedimentary covers (lentini et al., 1995; di stefano & lentini, 1995; lentini et al., 2000). synand post-orogenic sediments are represented by upper eocene and younger sequences, each indicating a stage in the polyphasic tectonic evolution of the area (lentini et al., 2000, and references therein). in detail, the main lithologic units are represented by the conglomerates and sandstone of the tortonian s. pier niceto fm, very thin messinian evaporite, pliopleistocene biocalcarenite and pleistocene-holocene coarse-grained fan deltas of the messina fm. the corresponding coastline has alternating gravelly/sandy shores and promontories. to the south, the volcanics of mt etna lie above the sedimentary meso-cenozoic successions. its recent effusive-type activity has been greatly influenced by the development of the neighbouring coast (longhitano & colella, 2007). in the last few centuries, lava flows from the eastern flank of the volcano have created a protrusive rocky shoreline, forming the northern margin of the gulf of catania. the volcanic coastal subprovince is characterised here by high cliffs, composed of resistent basalt alternating with scoriaceous lava flow deposits. 105coastal models and beach types ... all these lithologic units, differently involved in local drainage, are recognisable in the mineralogical composition of the sediments of the corresponding beach types pertaining to each single coastal province. sediment composition varies from metamorphic, carbonatic and arenaceous clasts on the northern coast, to fully volcanic on the southern coast. 2.3 uplift rates in the last few years, emphasis has been placed by the scientific community on evaluation of ne sicily coastal uplift rates and their relationship with onshore geology (bonfiglio & violanti, 1983; di grande & neri, 1988; firth et al., 1996; stewart et al., 1997; bordoni & valensise, 1998; rust & kershaw, 2000; monaco et al., 2000; antonioli et al., 2002, 2003; 2004a,b; kershaw & antonioli, 2004; antonioli et al., 2006). research on sea-level indicators (marine notches and 14c dated shells) close to the modern sea level at several locations along the coastline (firth et al., 1996; stewart et al., 1997; rust & kershaw, 2000; kershaw, 2000) show that different uplift rates were active during the pleistocene and the holocene. the messina strait area shows the highest longterm uplift rates in italy; bordoni & valensise (1998) indicate a rate of up to 1.2 mm a-1 over the last 125 ka. however, evidences reported by miyauchi et al. (1994) suggest that the sites of capo peloro and ganzirri are undergoing long-term uplift rates of 0.8 mm a-1. to the south, monaco et al. (2004) and antonioli et al. (2006) obtain holocene uplift rates of at least 2.4 and 1.2 mm a-1 for the taormina and capo sant’alessio localities (bordered by the messina fault system) and the etna area (bordered by the malta escarpment), respectively. new data from shell remains from the taormina area north of mt etna have been used to show that uplift over the past 6000 years (short-term) had a slower rate of about 1.4 mm a-1 (antonioli et al., 2003; kershaw & antonioli, 2004). 3. methods our observations were made along the studied coastline according to its geological characters and significance. for each site, shore profiles were measured, starting from mid-swash and moving landwards to the foredune. beachface sediments were sampled at points where relevant grain-size variations occurred. sampling density was designed with respect to the total length of profiles, varying from site to site and fig. 2 geological cross-section along ionian coast of sicily, showing coastal provinces and subprovinces proposed in this study. sezione geologica schematica attraverso la costa ionica della sicilia orientale, mostrante la suddivisione in province e sotto-province costiere proposta in questo lavoro. 106 depending on the local beach dimensions. sediment grain-sizes were compared with those of previous works (e.g. amore et al., 1992). statistics covered the means, standard deviations, skewness and kurtosis of grain sizes and settling velocity distributions of sediments. environmental parameters associated with the location of each sediment sample were determined from field observations and analysis of aerial photographs. beach morphology and shoreline stability were identified from bathymetric charts and interpretations deriving from previous works. for each single location, dean’s surf scaling (dss) parameter was calculated (dean, 1991), in order to define numerically the rate of energy dissipation or reflection along an idealised nearshore profile. estimates take into account the characteristics of the dominant wave motion and the physical features of beach sediments, according to the following formula: hb ω = ––––– (1) ws t where hb and t are breaker height and period respectively, obtained from local measurement stations between january 2003 and january 2006, and ws is mean sediment fall velocity. parameter ws was obtained from the following formula: 2 a2 (σ – ρ) g ws = ––– –––––––––––– (2) 9 η in which a and σ are particle grain size (radius) and density, respectively; ρ is fluid (marine water) density; g is gravity acceleration, and η is fluid dynamic viscosity. formula (2) derives from stoke’s law, in which falling velocity is proportional to the square of the particle radius (allen, 1982). formula (1) was calculated for nine sites. results are summarised in table 1. 4. coastal provinces the northern segment of the ionian coast of sicily has a regular n30°-trending shoreline, composed of various beach types. this coastal domain has a total length of 107.36 km and extends from capo peloro (to the n) to catania (to the s). on the basis of geological table 1 hydrodynamic setting of nearshore profiles for study areas (from n to s) along ne sicilian coastline, according to dean’s surf scaling parameter values. mean breaker heights and periods obtained from in situ measurements and ‘catania buoy’, mainly from january 2003 to january 2006. see text for explanation on mean sediment fall velocity. identità idrodinamica calcolata nei confronti dei profili sotto costa di ciascuna area di studio (da n verso s) lungo la costa nord-orientale della sicilia, secondo i valori del dean’s surf scaling parameter. l’altezza media dei frangenti ed il periodo sono stati ottenuti da alcune misure in situ e principalmente dai dati della ‘boa di catania’, nel periodo gennaio 2003-2006. fare riferimento al testo per il calcolo del valore ws. site of mean breaker mean breaker mean sediment dean’s measurements height (hb) period (t) fall velocity (ws) surf scaling beach-type (from n to s) m sec cm . sec-2 parameter (ω) capo peloro/ganzirri 0.32 6.34 0.39 5.2 intermediate messina 0.22 4.00 0.20 4.2 intermediate rocca lumera 0.089 5 0.075 5.9 intermediate/dissipative letojanni 0.089 7.10 0.10 6.1 slightly dissipative taormina 0.089 3.30 0.36 0.8 slightly reflective giardini-naxos 0.045 6.30 0.16 1.7 intermediate riposto/praiola 0.750 1.50 56,25 0.02 highly reflective fondachello 0.750 5.40 40,5 0.1 reflective catania/ognina 0.048 2 32 0.003 very highly reflective fig. 3 overall seawater circulation of ne sicily. s-directed, long-shore currents, due to messina strait, hydrodynamics interact with clockwise, offshore circulation of ionian sea. circolazione marina del settore nordorientale della sicilia. le correnti lungo costa, dirette verso meridione e generate dallo stretto di messina, interagiscono con le correnti a largo dello ionio, producendo dei locali movimenti rotazionali in senso orario. s. longhitano & a. zanini 107 and morphological characters, this province may be further divided into two subprovinces: (i) a northern segment, consisting of the ionian side of the peloritani mts from capo peloro to the city of riposto (first 75.1 km), where the kabilo-calabride terranes outcrop; (ii) a southern segment, made up of the volcanics of the eastern flank of mt etna, down to the city of catania. 4.1 coastal hydrodynamics the peloritani subprovince, is the coastal segment most strongly influenced by the complex messina strait seawater dynamics (de domenico, 1987). throughout this narrow waterway, connecting the tyrrhenian to the n and the ionian to the s, reverse flows of strong tidal currents occur in phase opposition every six hours, whereas in the microtidal regime of the mediterranean, tidal currents run at a speed of 6 or 7 knots on the surface (montenat et al., 1987). these hydrodynamics control seawater movement along the peloritani coastal subprovince, where a fan of sdirected currents develops (fig. 3). these flows give rise to ssw-directed long-shore currents, controlling the coastal drift of sediments. the seawater dynamics of the messina strait also influence water circulation along the southern coastal subprovince, where generally s-directed long-shore currents flow. here, they interact with the volcanic promontory of the eastern flank of mt etna and with nne-directed offshore circulation, producing a series of clockand anticlock-wise cells (longhitano & zanini, 2002), marked by the turbidity plumes of suspended loads debouching from the main rivers, visible in satellite photographs (fig. 3). 4.2 beach types the absence of a wide continental shelf which is characteristic of the ne coast of sicily has deeply influenced the morphology of the relative beach types. narrow beaches are generally found, extending for several kilometres. other types consist of strips of coarse-grained material, constrained between promontories. the average gradient is mediumhigh (up to 9°) and the isobaths of the nearshore zones describe a narrow, rapidly subsiding sea-floor: the bottom deepens regularly to -1000 or -1500 m, without any shelf break (ramp-type shelf). the beach types which are more representative of this coastal domain are described in four main sectors, located from n to s: (i) messina and (ii) taormina, within the peloritani mts coastal subprovince, and (iii) riposto and (iv) ognina (catania), within the mt etna subprovince. fig. 4 (a) view of capo peloro and ganzirri coastline; (b) geological map; (c) profile (modified after bottari et al., 2005). (a) vista panoramica di capo peloro e della costa di ganzirri. (b) schema geologico del settore e relativa sezione (c) (modificata, da bottari et al., 2005). coastal models and beach types ... 108 4.3 peloritani mts subprovince 4.3.1 messina area the messina and capo peloro types are represented by sandy beaches, ne-evolving to a sandy-gravelly spit, which grew during the late holocene transgression due to the action of littoral current circulation (segre et al., 2004). the beaches in the messina area are mainly formed of shingle and sandy types, with morphological configurations directly influenced by the high hydrodynamics of the messina strait. the capo peloro spit-peninsula (fig. 4a) extends from ganzirri to granatari-torre faro, and consists of a highstand lagoon and eolian coastal deposits overlying transgressive marine sand. the latter deposits represent middle pleistocene coastal wedges, prograding during a relative sea-level rise toward the messina strait and eroding lower pleistocene regressive fandelta deposits (messina fm., auct.; fig. 4b). the beach type that summarizes this geological framework shows a wide coastal plain, with a gentle landward inclination. this morphological setting derives from the accommodation space generated by roll-over of the normal-fault hanging-wall, where holocene saltmarsh sedimentation takes place (fig. 4c; bottari et al., 2005). the nearshore beach profile may be considered as the remnant of a beach-barrier system which, strictly controlled by the anthropogenic activity of the last few centuries, has lost its original morphology (fig. 5). the dss parameter calculated for the nearshore profile ranges from 4.1 to 5.2, indicating an intermediate stage between dissipative and reflective domains. this is also shown by the seaward increase in the beach gradient: the nearshore profile evolves from slightly dissipative to reflective type, although dominant wave energy is mitigated by the action of the messina strait tidal currents flowing parallel to the shore (fig. 6). 4.3.2 taormina area the taormina area comprises a number of promontories and islands (fig. 7), amounting to several kilometres of limestone-bordered coastline. this uplifted headland area is located on the relatively downthrown side of a major fault, whose strike corresponds to that of the messina system and which generally bounds the coastline in this area (rust & kershaw, 2000). the shore is represented by cliffs with debris accumulations at the base, without abrasion platforms. when present, the beach is compartmentalized into shingle pocket clast accumulations occurring fig. 5 (a) view from south of capo peloro and ganzirri area; (b, c, d): details of beach types occurring along coast. a) vista meridionale dei settori di capo peloro e ganzirri. (b, c e d) particolari dei modelli di spiaggia osservabili lungo questo litorale. s. longhitano & a. zanini within indentations (spisone, isola bella) and by sandy prograding beaches on the embayments (giardini-naxos, figs. 7a, 7b). the s-directed long-shore seawater circulation is diffracted by the irregular coastline and a series of local clockand anticlock-wise cells develop at local scale. beach sediments are composed of metamorphic and calcareous clasts, up to 30 mm in size, organized into a 5°-7° seaward-inclined narrow strip. along the shingle beach, relicts of ancient beachrock deposits formed of gently seaward-inclined conglomeratic beds occur, referable to a recent uplifted beach face (fig. 8). the beach for this sector can be described as a reflective-type profile, characterized by a staircase-type section (submerged data are from antonioli et al., 2003), with a dss rating of 0.8 (fig. 9). a sector which well represents the degree of morphological variability typical of this coastal subprovince is the area of giardini-naxos. located a few kilometers south of taormina, two promontories, the calcareous capo taormina (north) and the volcanic capo schisò (south) form a wide gulf (see fig. 6a). this particular morphology causes local seawater circulation which has given rise to a broad sandy shoal, during the last 5-6000 years (randazzo, 2003). this morphological setting locally changes the hydrodynamic framework of this part of the subprovince, from a reflective to a local dissipative (dss = 1.7) nearshore profile (fig. 8d). 109 fig. 6 beach type and nearshore profile of capo peloro/messina area. original morphology of previous beach-barrier system profoundly modified by anthropogenic activity along coast in last few centuries. (ω = dean’s surf scaling parameter; ws = mean sediment fall velocity; hb = mean breaker height; t = mean breaker period). modello di spiaggia schematico e profilo sotto costa relative al settore di capo peloro/messina. si noti come l’originale assetto morfologico di un sistema di tipo barra è stato profondamente modificato dall’azione antropica lungo costa degli ultimi secoli. fig. 7 (a) view of taormina and giardini naxos coastline; (b) geological map; (c) profile (modified after lentini et al., 2000). (a) vista panoramica delle aree di taormina e giardini naxos. (b) schema e relativo profilo geologico (c) (modificato, da lentini et al., 2000). coastal models and beach types ... 4.4 mt etna subprovince 4.4.1 local coastal hydrodynamics the eastern flank of mt etna has a typical morphology that reflects the progressive emplacement of historic and recent lava flows, due to effusive volcanic activity, reaching the sea and creating a peculiar coastal setting (monaco et al., 1997). here, currents driven by the messina strait also influence local seawater circulation, producing longshore s-directed and local n-directed currents. nearshore circulation is often diffracted and inhibited by the great complexity of the cliffed volcanic shoreline, marked by a number of small coastal promontories and indentations, created by eroding lava deltas. in this subprovince, only wave energy may be considered as a dominant factor affecting the shoreline and controlling beach sediment re-working. waves approach the coast obliquely, as a result of the s-directed currents. 4.5 riposto area the main tectonic and morphologic feature of 110 fig. 8 (a) panoramic view of taormina cliff, showing marine notch 5 m above present sea level; (b) isola bella promontory, connected at the coast to a gravel spit; (c) detail of shingle beach type, a few km n of previous photos; (d) beach type at giardini naxos. (a) veduta panoramica della falesia di taormina, mostrante un chiaro solco d’erosione marina posto ad un’altezza di circa 5 metri sull’attuale livello del mare. (b) il promontorio dell’isola bella, collegato alla linea di costa attraverso un sottile tombolo ghiaioso. (c) dettaglio della spiaggia ghiaiosa di spisone, pochi km a nord delle precedenti foto. (d) spiaggia sabbiosa di giardini naxos. fig. 9 beach type characterizing coastline of taormina area. a shingle, narrow beach is confined to inner part of a steep, dissipative-to-reflective nearshore profile. (ω = dean’s surf scaling parameter; ws = mean sediment fall velocity; hb = mean breaker height; t = mean breaker period). modello di spiaggia relativo alla costa taorminese. l’unica spiaggia ghiaiosa di piccole dimensioni che può svilupparsi appare chiaramente confinata nel settore più interno di un profilo di tipo dissipativo/riflessivo. s. longhitano & a. zanini eastern mt etna is the widespread nnwand nne-trending active fault system. the nnwsse-oriented timpe fault system is considered to be the inland extension of the malta escarpment (cristofolini et al., 1979; lentini, 1982). here, a coarse-grained fan-delta deposit occurs extensively (figs. 10a, 10b). the socalled ‘chiancone’ (k i e f f e r , 1969; 1970; romano & sturiale, 1981; di grande & di maggio, 1988) represents the largest etnean volcanoclastic sequence (del negro & napoli, 2002). some authors (e.g., c a l v a r i & g r o p p e l l i 1996; b o u s q u e t et al., 1998) have pointed out that this fan-shaped deposit has a submerged counterpart toward the ionian, which modifies the isobathic trend of this coastal sector (fig. 10c). the beach type is characterized by monogenic volcanic clasts, with the largest grain size observed along the whole ionian coast of sicily (fig. 11). during high-energy stages, waves rework the clasts along the swash zone, producing very impressive noise and vibration, perceptible quite far from the beach. beach morphology here is directly influenced by the size of the clasts, organized into three orders of berms and characterized by a seaward gradient of up to 10° (fig. 12). the dss parameter indicates a fully reflective nearshore profile, controlled by oblique wave incidence. according to monaco et al. (1997), the beach of this sector developed on the foot-wall of a normal fault. instead, our observations indicate that it represents sediments which accumulated during the end of the last sea-level rise, occupying the erosional platform caused by the sea during the present sea-level highstand. 4.6 ognina the youngest normal faults of the mt etna area are located along the base of the eastern flank of the volcano. nnwand nne-trending fault segments control the present coastal morphology, producing steep late pleistocene-holocene sea cliffs (monaco et al., 1997). the most impressive scarps extend for about 20 km from acireale to s. alfio, producing walls up to 120 m high (fig. 13a). the terrains forming this cliffed coast are made up of lava flows from eruptions of different ages (romano & sturiale, 1982) (fig. 13b). the coastal morphology is characterized by sea terraces, occupied by holocene alluvial volcanoclastic deposits (fig. 13c). the beach types considered most representative of the southern sector of this subprovince were studied n of catania, along the shoreline of ognina. here, anthropogenic activity is recent and less invasive, and the morphological characters of this coast are still well-preserved (fig. 14). the beach type is represented here by small pocket beaches, containing coarse-grained volcanic sediments, deriving only from rock-fall debris of the cliffs, attacked and eroded by the powerful action of 111 fig. 10 (a) view of the riposto and praiola coastline; (b) geological map; (c) profile (modified after del negro and napoli, 2002). (a) vista panoramica del settore costiero di riposto e praiola. (b) schema e profilo geologico del settore (c) (modificato, da del negro e napoli, 2002). coastal models and beach types ... waves. the nearshore profile reflects the morphology of a submerged lava delta front, characterized by a staircase-type sea-bottom which creates a very high reflective-type hydrodynamic setting (dss parameter 0.003) (fig. 15). 5. discussion and conclusions the subdivision of discrete segments of shoreline, based on the geological framework in which they developed in recent times, identifies the characters of the beach types in a more analytical way. the morphology 112 fig. 11 (a) cliff along praiola beach; (b) detail of same beach characterized by a series of storm berms; (c) volcanic cobbles and pebbles along swash zone; (d) detail of clast morphology. a) falesia vulcanoclastica lungo la spiaggia di praiola. (b) dettaglio della stessa spiaggia, caratterizzata da una serie di berme generate da episodi di tempesta. (c) clasti vulcanici lungo la zona di battigia. (d) dettaglio morfometrico dei clasti vulcanici. fig. 12 beach type of riposto/praiola site. nearshore profile is reflective, slightly dissipative. beach develops near a cliff cut due to present sea-level highstand. (ω = dean’s surf scaling parameter; ws = mean sediment fall velocity; hb = mean breaker height; t = mean breaker period). modello relativo alla spiaggia di riposto/praiola. il profilo sotto costa è di tipo riflessivo, leggermente dissipativo. la spiaggia si sviluppa occupando il solco erosivo formatosi durante l’attuale stazionamento alto del livello del mare. s. longhitano & a. zanini and sedimentology of each single coastal segment directly refer to a series of geological considerations, giving a complete framework of the coastal system. morphological and sedimentological observations collected from the sites of capo peloro-messina, taormina-giardini naxos, riposto and ognina-catania, in the northern coastal province of the ionian coast of sicily, describe a series of beach types which directly reflect the local geological framework. the present-day aspect of these beaches indicates by longmediumand short-term processes, the duration of which depended on the time over which they developed within the system. the general morphology of a coastal compartment influences beach characters in terms of longitudinal/lateral extension of sediments, prograding rate, and wave influence on long-shore sediment distribution. all these elements are long-term features, directly influencing the local geology. in contrast, a series of several different features may be appreciated in beaches, where short-term control processes are active. for example, beach gradient and the physical organization of sediments along the beachface are parameters which depend on grain size and recent hydrodynamics which, in turn, derive from local meteomarine conditions. an exception to these considerations is the coastal uplift rate, especially when recent vertical movements are very rapid. the examples observed in the ne coastal province of the ionian sicilian shoreline show several coastal compartments characterized by high uplift rates. the time-span over which vertical coastal movements have been calculated (125÷5 ka) and their influence on coastal morphology are considered as medium-term controlling factors for the development of a coastal sector. the beach types developing along uplifting coasts are regarded as the variables of a coastal system which best record this condition. the hydrodynamic identity of each study site, quantified by dean’s surf scaling (dss) parameter, characterizes the dynamic behavior of every beach and its relative nearshore zones. the results are transitional between dissipative, slightly dissipative, and reflective nearshore profiles, depending not only on the parameters included in the calculation (sediment grain size, mean breaker height and length, etc.) but also on the coastal gradient of the bedrock on which the beach developed during recent times. the gradient of the bedrock is strongly controlled by vertical tectonic coastal movements, which are expressed in coastal uplift rates. assuming this background, every beach profile, 113 fig. 13 (a) view of ognina and catania volcanic coastline; (b) geological map; (c) profile (modified after monaco et al., 2000). (a) vista panoramica relative al settore costiero di ognina e catania. (b) schema e profilo geologico del settore (c) (modificato, da monaco et al., 2000). coastal models and beach types ... 114 fig. 14 (a) panoramic view of ognina coastline (from south), typically characterized by lava deltas of historic etnean eruptions; (b) view of same coast (from north) where pocket beaches composed of volcanoclastic detritus occur; (c) detail of columnar, basaltic cliff; (d) pocket beach at toe of cliff in previous photo. (a) veduta panoramica meridionale del settore costiero di ognina, caratterizzata da spandimenti lavici appartenenti alle eruzioni storiche dell’etna. (b) veduta settentrionale del medesimo tratto costiero, dove si sviluppano alcune isolate pocket beach costituite da clasti esclusivamente di natura basaltica. (c) dettaglio dei basalti colonnari che costituiscono una parte della falesia vulcanica. (d). dettaglio di una pocket beach presente alla base della falesia ritratta nella foto precedente. fig. 15 beach type of ognina/ catania site. beach occurs at toe of a basaltic cliff, created by erosive action of waves. beach sediment derives only from debris produced by wave erosion. reflective type of nearshore profile implies highenergy hydrodynamics and temporal suspension of coarse clasts during storms. (ω = dean’s surf scaling parameter; ws = mean sediment fall velocity; h b = mean breaker height; t = mean breaker period). modello di spiaggia relativo al settore di ognina/catania. i clasti basaltici si attestano alla base della falesia lavica prodotta dall’azione meccanica dell’erosione del moto ondoso. il sedimento deriva esclusivamente dal crollo di porzioni della parete vulcanica. il comportamento idrodinamico di tipo riflessivo del profilo sotto costa determina la temporanea sospensione di clasti anche di grandi dimensioni durante le fasi di alta energia. s. longhitano & a. zanini with its morphological, sedimentological and hydrodynamic features, may be referred to the local coastal uplift rate. fig. 16 displays the gradient and grain-size of nearshore profiles on the y-axis, and the relative distance along the ionian coast of sicily on the x-axis. the first parameter (range: 1÷5) indicates the gradient of the nearshore profile and the sediment grain-size for each single site of observation. as these two characteristics vary in the same way, as gradient and sediment grain-size increase, index values vary progressively from 1 to 5. the uplift rates on the righthand y-axis define discriminated classes of uplfiting coasts. all these combined parameters show a normal correlation with a gradual transition between dissipative and reflective beach types. the continental shelf progressively spreads eastward from northern to southern coastal subprovinces (fig. 16) and shows two main groups of beach types. the first group corresponds to the models of the northern sector, where the continental shelf progressively thins northwards and the beach types show wide, dissipative-type, sandy inshore profiles, characterized landwards by well-developed alluvial plains. the beach gradients observed at capo peloro, messina and letojanni are medium-low, and uplift rates of up to 0.8 mm a-1. the second group contains taormina, riposto and ognina, where the continental shelf widens southwards, and the beach types are narrow, coarse-grained and cliffed with a medium-high gradient and uplift rates of up to 2.4 mm a-1. thus, the ionian coastal province of ne sicily shows beach types with morphology mainly influenced by local uplift rates, rather than by continental shelf width. another way of describing the beach types occurring in the studied subprovinces is shown in fig. 17. this block-diagram has a series of differing coastal profiles and models, taking each beach type into account: (i) bedrock lithology; (ii) the nature of the feeder system of a given shoreline; (iii) local uplift rates. in the model of fig. 17, where beach types are displayed in no geographic order, as uplift rates increase (ranging from 0.7 to 2.4 mm a-1), the feeder systems evolve from wide, well-developed, alluvial braided plains (letojanni), to torrential-type coarse-grained 115 fig. 17 some coastal profiles and models occurring along study coastline and related to changes in uplift rates. in this type of correlation, wave energy, sea-bottom gradient and beach sediment grain-size correspond directly to various classes of coastal vertical movements. diagramma che mostra alcuni differenti modelli costieri sono stati individuati lungo litorale studiato, in funzione della variazione dei tassi di sollevamento. in questo tipo di correlazione, l’energia del moto ondoso, il gradiente del fondale sotto costa e il diametro medio dei sedimenti corrispondono a differenti classi di movimenti verticali della costa. fig. 16 correlation between sediment grain-size and gradient of each nearshore system (studied here) (left-hand y-axis), with local coastal uplift rates (right-hand y-axis), with relative distances of study sites (lower x-axis). note progressive changes in hydrodynamic behavior of each profile from ‘dissipative’ to ‘reflective’ as uplift rate increases. progressive, southward enlargement of continental shelf does not correlate with gradient of inshore profile. diagramma mostrante la correlazione tra diametro dei sedimenti e gradiente di ciascun sistema di spiaggia considerato nel presente studio (asse di sinistra delle ordinate) con i locali tassi di sollevamento (asse di destra delle ordinate), riferiti alle rispettive distanze (relative e cumulative) che separano le diverse aree studiate (asse delle ascisse). si noti una progressiva variazione nel comportamento idrodinamico di ciascun singolo profilo da ‘dissipativo’ a ‘riflessivo’ all’aumentare della velocità del tasso di sollevamento locale. la progressiva espansione verso meridione della piattaforma continentale sembra non correlarsi direttamente con questa caratteristica. coastal models and beach types ... meandering streams (messina and giardini naxos) and then to alluvial fans (riposto), directly influencing the beaches. the vertical tectonic movements affecting the coastal bedrock strongly influence the sedimentation style of the supply systems and the morphology of the beach types which develop here show no influence of continental shelf morphology. correlations between the morphology and sedimentology of a beach type and the local uplift rate may thus represent a useful tool in discriminating behavior, and may perhaps be applied to other similar coastal systems. however, the model is hypothetical and needs to be verified by means of a wider range of case studies, like those represented by the beaches in the central-southern part of the ionian coast of sicily. acknowledgments we are grateful to prof. mario grasso (university of catania) and an anonymous referee for their useful and productive review of the manuscript. financial support for this study was provided by the ministero dell’università, grant 60% (a. zanini). references allen j.r.l., 1982 sedimentary structures: their character and physical basis. vol. i, elsevier scientific publishing company, new york, pp. 593. amodio morelli l., bonardi g., colonna v., dietrich d., giunta g., ippolito f., liguori v., 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nell’area ancora più sud-occidentale, invece, sono presenti rocce ignee e, da n verso s, si sviluppa una delle più grandi depressioni intermontane umbre rappresentata dal lago tiberino, che ha permesso la sedimentazione di importanti spessori di depositi fluvio-lacustri. in particolare, si può notare come la memoria “storica” dei passati paesaggi geologici si evinca anche dall’ edificato urbano più antico che racconta attraverso le cinta murarie, i monumenti, ma più spesso le semplici abitazioni, il primo paesaggio di cui gli abitanti dei luoghi hanno fruito come materiale da costruzione. il centro storico di città della pieve, infatti, si erge al top del delta del paleo-nestore e, con i suoi depositi, sono state edificate le mura ed i palazzi del centro abitato mentre, l’ etrusca orvieto ricava dalla piastra tufacea della sua “mesa”, la roccia per costruire la città epigea e le tombe al di fuori delle mura cittadine. anche le tombe estrusche dell’ipogeo del volumni, a perugia, ubicate nella parte medio-distale del paleo-delta del f.tevere, sono situate in ambienti scavati all’interno dei depositi deltizi. la bella civita, la “città che muore”, presso bagnoregio è costruita con la roccia tufacea e basaltica su cui è ubicata, mentre l’antica carsulae, presso terni, si fregia nel suo antico sviluppo urbano dei calcari e dei travertini della struttura dei m. martani; infine, la città di assisi che appare “rosea” perché, ancora oggi, edificata con la scaglia rossa della serie umbro-marchigiana. questi esempi rappresentano solo alcune delle realtà litologico-archeologiche presenti nel tessuto urbano delle città dell’umbria. le vicende geologiche e il conseguente paesaggio hanno decisamente condizionato non solo l’ubicazione delle città, ma anche la loro tipologia edilizia che si è avvalsa, quasi sempre, dei materiali “autoctoni”. la locale storia geologico-geomorfologica ha trasmesso, pertanto, all’edificato urbano un importante valore scientifico e culturale. abstract: l. gregori, geologic-geomorphologic “memory” in some of umbria's cities and surroundings by means of ancient urban building materials. (it issn 0394-3356, 2007). the complex geological history of umbria has led to an extreme lithological and geomorphological variability. calcareous lithotypes are present, deriving from apenninic structures, bordering the region towards east, while siliciclastic lithotypes crop out in the west part of the region and igneous rock in the south-east part. the whole region is crossed from north to south by one of the greatest intramountain depressions in umbria, i.e. the tiberino lake, which has allowed the sedimentation of imposing fluvial and lake deposits. the historical “memory” of the past geologic landscapes can be deducted also by means of the most ancient urban buildings. the city walls, the monuments and also the simple houses of common people bear witness of the landscapes where the early inhabitants of the region used to carve out building materials. typical examples are the town of città della pieve, located on top of the nestore paleoriver which supplied raw materials for walls and buildings, and the etruscan town of orvieto, where the tufaceous stone has been carved out from the mesa to build the underground town and the tombs outside the city walls. also the etruscan tombs of the volumi hypogeum, located at the fore/bottom-set of the tevere river paleodelta, are carved into deltaic deposits and behind the tombs of the etruscan noble families conglomerated banks crop out, alternated by sands and/or muds. the beautiful town of civita, “the dying town” near bagnoregio is carved out directly from the tufaceous and basaltic stone onto which it lays and the ancient town of carsulae, near terni, has used for its urban developments calcareous and travertines materials coming from martani mountains. finally, the world famous city of assisi has its buildings and churches built from the typical pink stone extracted from the quarry of the subasio mountain. these are some of the examples representing litho-archaeologic situations in the urban fabric of umbria's cities.the geologic history and the subsequent surfaces aspect of the region have definitely influenced not only the location of urban sites but also their building typology which, almost always, has made use of the native raw materials provided by the geologic and geomorphologic history of the region, assigning to them a great value both scientifically and culturally. parole chiave: paleogeografia,geomorfologia,geo-archeologia, umbria. keywords: palaeogeography,geomorphology,geo-archaeology, umbria region. il quaternario italian journal of quaternary sciences 19(2), 2006 269-278 1. introduzione il presente lavoro vuole proporre una conoscenza dell’umbria attraverso una nuova chiave di lettura, quella degli elementi geologici e geomorfologici del territorio. la geodiversità umbra conseguenza delle sua storia geologica ed evolutiva si traduce in una grande varietà di paesaggi percepibili, con un metodo di indagine non tradizionale, anche attraverso le differenti tipologie dell’edificato delle città. la “memoria storica” (sensu piacente & poli, 2003) dei luoghi umbri racconta di concentrazioni urbane in siti rilevati come al top dei paleo-conoidi, luoghi privilegiati per motivi strategici e di salubrità (in umbria, nelle depressioni occupate dai laghi era presente, fino a 270 l. gregori tempi storici, la malaria) o arroccate nell’alto delle inespugnabili mesa o lungo le sponde dei fiumi, talora, uniche vie di penetrazione nel territorio. uomo e territorio sono pertanto fortemente collegati: il substrato geologico con le vicende geomorfologiche che lo hanno interessato ha quindi, influenzato lo sviluppo demografico costituendo non solo un semplice bed-rock ma, talora, attraverso i diversi litotipi in affioramento, ha fornito il materiale da costruzione o modellato superfici, talora rilevate, risultate idonee all’edificazione; le situazioni ambientali indotte da alcuni processi morfogenetici, inoltre, potevano rappresentare una risorsa (ad es.: pedogenesi) o un ostacolo (aree in frana) all’antropizzazione. e’ interessante notare come dall’analisi, quindi, delle relazioni tra la tipologia edilizia delle città e le caratteristiche geologico-geomorfologiche del sito su cui esse si sono sviluppate, emerga la memoria di antichi paesaggi ambientali. l’edificato urbano, infatti, più o meno datato (in alcune località, come assisi, persiste ancora la tradizione dell’uso edilizio del litotipo locale) racconta, attraverso i monumenti, ma più spesso attraverso le normali abitazioni, l’antico scenario geologico. saranno, pertanto, proposte nel presente lavoro alcune situazioni in umbria, interessanti sotto questo aspetto e nell’ottica di un approccio divulgativo, ma scientificamente rigoroso. il percorso proposto, infatti, evidenzia ed integra gli aspetti scientifici dei luoghi con le loro peculiarità artistico-monumentali e il loro generale valore ambientale: cogliere gli elementi geologici anche nell’edificato delle città può pertanto rappresentare una insolita e stimolante modalità di divulgare tematiche geologico-geomorfologiche. 1.1 inquadramento geologico-geomorfologico la complessa storia evolutiva dell’ umbria ha determinato una estrema variabilità litologica e morfologica nel territorio della regione (jacobacci et al.,1970): le strutture appenniniche la limitano verso est, attraverso la sequenza delle anticlinali calcaree est-vergenti, mentre litotipi silico-clastici affiorano prevalentemente nella porzione più occidentale dove i rilievi, in virtù del minore dislivello, hanno una diversa evidenza dal punto di vista morfologico (fig.1a). nell’area più sud-occidentale, invece, sono presenti le rocce ignee del vulcanismo pleistocenico che conferiscono al paesaggio morfosculture abbastanza spettacolari (gregori et al., 2005). tutta la regione, infine, da n verso s è attraversata da una delle più grandi conche intermontane pliopleistoceniche umbre, rappresentata dall’antico bacino tiberino (lotti, 1926; cattuto et al., 1992) : questa ampia depressione di origine tettonica assume una forma a “y” rovesciata e, all’altezza del centro abitato di perugia, si divide in due “rami”, uno orientale diretto verso spoleto ed uno occidentale fino a todi/corbara (fig. 1b). nel lagotiberino sono stati deposti, a partire dal pliocene, imponenti spessori di depositi fluvio-lacustri e/o palustri e, pertanto, la storia del bacino ha avuto un importante ruolo nell’evoluzione morfologica del territorio. nella porzione più sud-occidentale della regione, infine, l’evento morfologico più recente è rappresentato dalle colate laviche dell’apparato di bolsena, giunte fino alla valle del f.paglia, a ne di orvieto; si tratta delle vulcaniti vulsine: tufi stratificati/colate leucitiche, ignimbriti del pleistocene medio (cattuto, cencetti & gregori in aa.vv.,1994; stoppa in aa.vv.,1994) modellate, nelle spettacolari mesa, dai successivi processi morfogenetifig. 1 – (a) inquadramento geografico e geologico schematico dell’umbria (modificato da guzzetti & cardinali,1989: 1) formazioni calcaree e calcareo-marnose della serie umbro marchigiana (giura-oligocene); 2) formazioni torbiditiche (miocene); 3) depositi di facies marina, salmastra e continentale (plio-pleistocene); 4) depositi vulcanici dei m. vulsini (pleistocene). (b) il lago tiberino (lotti,1926). geographic and geological arrangement of the umbria region (modified by guzzetti & cardinali,1989): 1) calcareous formations.of umbria-marchigiana serie (giura-oligocene); 2) torbiditic formations (miocene); 3) sea and continental deposits (plio-pleistocene); 4) volcanic deposits (pleistocene). (b) the tiberino lake. a) b) ci (weathering, morfoselezione, frane, ecc.). nell’umbria, a grande scala, si possono quindi individuare quattro unità di paesaggio (sensu ecologia del paesaggio; delcourt & delcourt,1988): quella dei rilievi calcarei, quella dei più modesti rilievi arenacei e l’unità delle zone depresse occupate prevalentemente da depositi fluvio-lacustri mentre, a sé stante, è quella rappresentata dal dominio vulcanico. tali diverse unità geologiche hanno portato a significative differenze morfologiche e quindi ambientali s.l. condizionando l’evoluzione del paesaggio sia naturale che antropico. 2. la litologia di alcuni siti e monumenti umbri vengono, di seguito, individuati alcuni siti in umbria le cui caratteristiche litologiche sono chiaramente riconoscibili nelle strutture edilizie delle città, al fine di cogliere quegli elementi di carattere geologicogeomorfologico e sedimentologico che possano essere trasmessi ad una utenza culturalmente più ampia. 2.1 dal paleo-delta di città della pieve al conoide di foligno nell’area settentrionale dell’ umbria affiorano, quindi, prevalentemente rocce arenacee che costituiscono sia i versanti dell’alta valle del f. tevere, che i rilievi che bordano il lago trasimeno e, in continuità litologica e morfologica, interessano anche le confinanti colline toscane. nella zona di città di castello di conseguenza, si rileva a scopo edilizio, l’uso della roccia appartenente alla formazione della marnoso-arenacea (successione etrusca o dell’umbria occidentale; in damiani in aa.vv.,1994) e, nell’area del lago trasimeno, delle arenarie del trasimeno e/o “macigno” riferite all’oligocene superiore (damiani in aa.vv.,1994) e denominate anche “pietra serena”. sia i pregevoli palazzi nobiliari di note città che i suggestivi casolari delle campagne toscane ed umbre, creano una continuità edilizia, ben raccordata, al diffuso affioramento delle rocce silico-clastiche. il paesaggio tosco-umbro, infatti, ha un aspetto litologico e cromatico caratteristico che però muta decisamente, andando verso s. procedendo verso se, in corrispondenza dei rilievi calcarei, analogo condizionamento geologico-strutturale si rileva nei centri abitati appenninici, attraverso la pietra calcarea squadrata del palazzo dei consoli di gubbio, della rocca di gualdo tadino e di tutti quei centri abitati, ubicati al contatto tra il bed-rock e le sottostanti pianure. le sinclinali arenacee e le anticlinali calcaree si potrebbero evincere anche dalla variabilità edilizia, attraverso una procedura analitica assolutamente non tradizionale, ma in linea con l’orientamento e la “filosofia” della geomorfologia culturale (panizza & piacente, 2003; 2005). verso w, le rocce affiorati denunciano la presenza, nel pliocene, di una linea di costa verso cui si dirigevano i corsi d’acqua dell’entroterra, edificando estesi corpi deltizi. e’ interessante notare come il centro abitato di città della pieve si collochi al di sopra di un ampio delta che appare morfologicamente rilevato rispetto alla valle del t.chiani; la cittadina si staglia, infatti, sul fronte 271la “memoria” geologico-geomorfologica in alcune città ... del rilievo deltizio edificato, nel pliocene, dal paleonestore insieme ad un deflusso, proveniente grossomodo da n (cattuto et al.,1992; gregori, 2005) e diretto verso la paleo costa, ubicata lungo l’attuale valle del f.paglia. la serie deltizia pievese, è costituita dalla nota successione sedimentaria pliocenica suddivisa in argille di fabro, sabbie a flabellipecten e conglomerato di città della pieve (ambrosetti & basilici in aa.vv.,1994). la morfoscultura che progradava verso ovest, ha così fornito, attraverso i depositi grossolani di top-set, la materia prima per costruire le mura ed i palazzi della città. i ciottoli arrotondati dell’antica piana deltizia prospiciente l’antico mare pliocenico, sono stati messi in opera interi o dimezzati (fig. 2), producendo uno stile edilizio ed una sorta di decorazione reiterata che contraddistingue la cittadina ma che, generalmente, sfugge ad uno “sguardo non geologico”. la città, nel suo insieme, assume inoltre una colorazione rossastra per il laterizio diffusamente utilizzato, anche per la facile reperibilità in loco, dell’argilla presente lungo l’area corrispondente alla costa pliocenica ed alla porzione distale del delta pievese (fig. 3). questo antico scenario è fig. 2 i ciottoli del top-set del paleo-delta del f. nestore nelle mura di città della pieve. the cobblestones of the paleo-delta topset of the nestore river, in the town walls of città della pieve. fig. 3 dem (regione umbria) del paleo-delta di città della pieve. digital elevation model (umbria region) of the paleo-delta in città della pieve. 272 percepibile anche nell’edificato più antico della città dove, è interessante osservare la pila sedimentaria (banconi di conglomerati e sabbie) dei depositi deltizi che “affiora” anche lungo le pareti degli edifici più datati, come le cantine storiche della città. la fattura delle antiche mura, in particolare, appare molto originale e colpisce un osservatore molto attento per l’originale tipologia edilizia, incrementata del suo “valore paleogeografico” che fornisce, pertanto, un tipo di informazione, ai più sconosciuta, ma che diventa anche messaggio scientifico. stessa tecnica edilizia è stata adottata anche in altre situazioni in umbria, e si può riconoscere, ad esempio, lungo alcune porzioni delle mura esterne di foligno. la città è ubicata, nel ramo orientale del paleo-lago tiberino, ai piedi della struttura m.brunette/ m serano, in corrispondenza dello sbocco nella valle umbra del f.topino. il bacino idrografico del fiume insiste prevalentemente sui litotipi calcarei della serie umbro-marchigiana, compresi fra il lias inferiore ed il miocene superiore-oligocene (dal calcare massiccio alla marnoso-arenacea; accordi & moretti, 1967). la presenza e la provenienza dei ciottoli usati nella costruzione della cinta muraria è una chiara evidenza sedimentologica legata all’ evoluzione dell’antico delta-conoide del paleo -topino, che progradava, verso w e sul quale la città è stata edificata.tale estesa morfoscultura, che ha avuto un ruolo importante nell’evoluzione del lago tiberino, non ha una chiara evidenza morfologica (ben desumibile attraverso elaborazioni digitali; fig. 4) per cui appare poco rilevata (foligno è comunemente definita “città di pianura”); una passeggiata, tuttavia, lungo le mura esterne (fig. 5), permette di cogliere un uso di materiali, simile a quella di città della pieve e di percepire processi morfogenetici ed un paleo-ambiente oggi non più riconoscibile a causa, anche, degli effetti della forte pressione antropica locale. questa integrazione fisica tra paleo-forme ed urbanizzazione è riconoscibile in molte località: città della pieve, foligno, montefalco ed anche perugia sono solo alcune delle “città-conoidi” umbre edificate al di sopra e con i materiali di questi estesi corpi sedimentari, che progradavano in mare o nei numerosi laghi umbri (localmente fusi nel grande bacino tiberino) e che, con le loro evidenze morfologiche e litologiche, hanno comunque segnato il destino e l’aspetto delle future città. 2.2 il paleo-delta del f. tevere particolarmente significativo è l’esempio della città di perugia, edificata sul top-set del paleo-delta del f.tevere. una suggestiva evidenza morfologico-sedimentologica del processo fluviale si rileva, quindi, nel fig. 4 dem modificato del conoide del f. topino (melelli, 2004). modified dem of the topino river fan. fig. 5 i ciottoli calcarei del f.topino nelle mura della città di foligno. town walls of foligno, built using calcareous cobblestones from the topino river. territorio perugino costituito da depositi continentali fluvio-lacustri, rilevabili lungo l’apparato deltizio che, nel pliocene, si gettava nel lago tiberino, a s di perugia ed il cui profilo è ancora riconoscibile percorrendo la stral. gregori 273 da che, da perugia, scende verso la valle del tevere. al raccordo con la pianura che si estende, infatti, ai piedi della città (presso ponte s.giovanni), in corrispondenza del passaggio fra i depositi di fore-set e bottom-set del paleo-delta, sono ubicate le splendide tombe etrusche dell’ipogeo del volumni. le urne sepolcrali, realizzate prevalentemente in travertino, si trovano all’interno di ambienti scavati nei depositi medio-distali del delta; alle spalle delle raffinate sculture delle urne, raffiguranti gli appartenenti alle nobili famiglie etrusche affiorano, infatti, i banconi conglomeratici alternati a finissime sabbie e limi cementali (fig. 6), clino-stratificati verso quella pianura, una volta occupata dal lago tiberino. la visita all’ ipogeo può costituire, così, un esempio eclatante e particolarmente interessante di “sinergia culturale” tra sedimentologia, geomorfologia ed archeologia, per una migliore comprensione dei luoghi e una nuova “percezione” dei loro processi naturali e antropici. 2.3 le “mesa” di orvieto e di civita/bagnoregio nell’area sud-occidentale dell’umbria, come accennato, litotipi e forme sono abbastanza esclusive e diverse da tutto il resto della regione: sono presenti litotipi vulcanici legati all’ attività dell’apparato di bolsena e tale evento morfologico è ben evidente nel tessuto urbano dei locali centri abitati. l’ orvieto etrusca è fondata su un piastrone tufaceo (ignimbrite di orvieto; giacomelli & scandone, 2002) della potenza massima di 70m, che nel pleistocene medio (da 600.000 a 300.000 anni fa; giacomelli & scandone, 2002) si è messo in posto al di sopra della serie dell’albornoz (livelli di materiali sedimentari e/o vulcanici; pialli et al., 1978) e delle argille marine plioceniche. l’acropoli appare, quindi, in continuità litologica con il banco piroclastico della sua mesa, e non risulta percepibile, neanche dal punto di vista cromatico, il passaggio dalla roccia in posto della rupe di orvieto alle pietre, squadrate o lavorate, messe in opera nell’edificato. la rupe, inoltre, è “svuotata” al suo interno, dalla storica coltivazione di antiche ed ampie cave sotterranee finalizzate, sia alla costruzione della orvieto epigea che delle tombe immediatamente a ridosso della rupe e dei “santuari” (come il tempio federale fanum voltumnae ritrovato, in recenti scavi archeologici, in corrispondenza dell’ antico “lago di velzna”, in località “campo della fiera”, tra la mesa di orvieto e il plateau alfino) (fig. 7; cattuto et al., 2002). la roccia vulcanica, quindi, ha accompagnato in questo luogo, le vicende dell’ uomo in tutte le fasi della vita, a partire dalle pregevoli decorazioni negli stipiti delle porte orvietane, alle curiose colombaie (fig. 8) lungo il perimetro esterno della rupe, alle capienti cisterne ipogee, utilizzate per la conservazione dell’acqua e l’ invecchiamento del vino, fino agli edifici sepolcrali (bizzarri,1998). l’edilizia moderna si avvale ancora dei basalti dell’alfina, materiale caratterizzato da ottime fig. 6 l’ ipogeo dei volumni: nelle cripte sono visibili i depositi del paleo-delta del f.tevere. the volumni hypogeum: conglomerated deposits of the tevere river’s paleo-delta are visibile in the crypts. fig. 7 frammento di antefissa a testa di satiro, riferita a materiali fittili, lungo una strada realizzata con “basoli” di leucitite e basalto (campo della fiera nei pressi di orvieto in cattuto et al., 2002). fragment of antefissa, representing the head of a satyr.. it refers to ancient fictile materials and it has been discovered near a road built with "basoli" (flog-stones) of leucitite and basalt, in the town of campo della fiera, near orvieto (cattuto et al., 2002). la “memoria” geologico-geomorfologica in alcune città ... 274 qualità geomeccaniche, quando lastricava, oggi come nel passato, con stupendi “basolati” (fig. 9) le strade tra l’altopiano alfino e la mesa orvietana (cattuto et al., 2002). nell’estremo sud-occidentale dell’umbria, ed in continuità litologia con l’altopiano dell’alfina, nei pressi di bagnoregio (al confine umbria-lazio) si trova il centro abitato di civita (fig.10), la famosa ed unica “città che muore”. anche in questo caso, il centro abitato è edificato esclusivamente con la roccia tufacea (“tufo di bagnoregio”; giacomelli & scandone, 2002) sulla quale e della quale è costruita: piccola mesa circondata da un biancheggiante e dinamico paesaggio a calanchi. la sequenza delle rocce ignee, ben esposta alla base del moderno ponte che permette l’accesso a civita, è costituita da prodotti ignimbritici sedimentati al di sopra delle argille plio-pleistoceniche (giacomelli & scandone, 2002). il suggestivo panorama dei calanchi, che si gode dall’alto dei giardini arroccati sul bordo esterno della mesa, è frutto di processi di erosione e fenomeni gravitativi che minacciano l’integrità e la stabilità del nucleo storico, e per questo, recentemente, nell’area interessata dai fenomeni calanchivi sono stati condotti interventi di bonifica. la necessaria salvaguardia del sito storicomonumentale, unico nel suo genere, ha imposto la stabilizzazione dei versanti tufaceo-argillosi su cui poggiano le vulcaniti, ma con la graduale ed inevitabile perdita di uno scenografico paesaggio naturale esclusivo, nel suo genere. in questo caso, il contributo di discipline come la geologia, la geomorfologia e la geologia applicata si integrano perfettamente in un contesto “geoturistico”, per una più profonda acquisizione delle caratteristiche del luogo. 2.4 le rocce carbonatiche nell’edificato umbro le rocce carbonatiche sono presenti in quasi tutta la parte più rilevata della regione ed, in particolare, assumono un ruolo importante nell’architettura di città turisticamente note come assisi, perugia,spoleto, ecc. l’area centro-meridionale dell’umbria (spoletoterni) è caratterizzata prevalentemente dai litotipi carbonatici della serie umbro-marchigiana. le rocce calcaree delle strutture umbre sono presenti, per esempio, a spoleto sia nei monumenti all’interno della città (es.: l’arco di druso, le fontane, le abitazioni più datate ed alcune chiese come il duomo) che nel ponte delle torri, al di fuori delle mura storiche.i calcari del m.luco e delle strutture bordiere del versante orientale della valle umbra (monti di campello) sono stati utilizzati per la realizzazione di parte delle alte ed imponenti arcate dello spettacolare ponte, simbolo storico e culturale della città (fig. 11a). nei pressi della città affiorano, infatti, prevalentemente litotipi delle formazioni giurassiche della serie u.m.(dal calcare massiccio, corniola e rosso ammonitici fino alla scaglia). anche l’antica carsulae, presso terni, nell’umbria meridionale, si fregia nel suo antico sviluppo urbano e monumentale, delle rocce calcare che provengono dalla struttura dei m. martani (fig.12) e degli estesi affioramenti di travertino presenti nelle vicinanze: calcari e travertini biancheggiano vistosamente nei ruderi della città. un’ampia fascia travertinosa potente 50m si trova lungo il versante occidentale dei m.martani, da acquasparta fino alla placca dei travertini di fig.8 le colombaie ricavate lungo il bordo della rupe di orvieto. the dovecots carved into the edge of the orvieto cliff. fig. 9 un antico “basolato” ai piedi dell’altopiano dell’alfina; la superficie pianeggiante del plateau è visibile sullo sfondo (cattuto et al., 2002). an ancient “basolato” at the base of the alfina plateau and the plane surface its visible in the background (ca t t u t o et al.,2002). l. gregori 275 a) b) fig. 10 il centro abitato di civita (a) e la sua piazza principale (b) “ raccontano” la roccia vulcanica della mesa. the centre of the civita village (a) and the main square (b) tell about the volcanic rock of the “mesa”. a) b) a) b) fig. 11 spoleto: il ponte delle torri costruito con conci di calcare dei “monti di spoleto” (a) e la fontana del mascherone in travertino (b). spoleto: the “towers bridge”, built with calcareous rocks from the spoleto mountains (a) and the mascherone fountain, built using travertine (b). fig.12 carsulae: calcare e travertino nel lastricato della via flaminia; sullo sfondo i rilievi della struttura dei m.martani (a) e nelle vestigia monumentali dell’arco di s. damiano (b). carsulae: limestone and travertine in the flaminia road paving ; in the background, the relieves of the martani mountains (a) and the monumental vestiges of s. damiano arch (b). la “memoria” geologico-geomorfologica in alcune città ... s.terenziano (pleistocene; ambrosetti & basilici in aa.vv. 1994). i materiali utilizzati nelle decorazioni di molti monumenti e fontane dell’umbria (fig.11b), inoltre, provengono dalle zone citate e dagli altri depositi di travertino abbastanza diffusi nella regione : i banchi di s.sabina, grutti s.terenziano, i travertini lungo il f. menotre presso la cascata di pale, fino allo spesso banco (circa 100m) che affiora lungo la valle del f.velino e nel salto della cascata delle marmore (frondini & peruzzi in aa.vv.,1994; gregori & troiani, 2005), all’estremo meridionale del paleo-lago tiberino. il travertino, inoltre, è presente, e non solo come pietra ornamentale, in molti edifici storici delle città umbre: l’ arco etrusco e la cinta muraria etrusca del nucleo storico perugino (le mura etrusche in travertino sono all’interno della cinta medievale in arenaria), sono state edificate con blocchi squadrati di roccia, proveniente dagli estesi affioramenti di s. sabina (*), località nei pressi di perugia (fig. 13). sono riconoscibili ancora calcari, nel paesaggio urbano di assisi che assume nell’insieme una tonalità “rosata”, a causa della roccia calcarea locale, detta “pietra di assisi” (fig. 14) usata, da tempi immemorabili, 276 a) b) fig.13 l’arco etrusco (a) e le mura, di perugia (b), edificate con il travertino che affiora in località s. sabina (presso perugia). in perugia, the etruscan arch (a) and the town walls (b) were built using travertine cropping out in the s.sabina area (near perugia). a) b) fig. 14 la scaglia rossa visibile in affioramento, a contatto con le mura storiche (a) e nell’ usuale edificato urbano di assisi (b). the “scaglia rosata” stone appears at the contact with historical walls (a) and it is also commonly used as building material in the town of assisi (b). l. gregori per la costruzione dei palazzi e delle decorazioni e presente nei fregi e nei pavimenti delle celebri chiese assisane; la roccia, squadrata dal lavoro di generazioni di abili scalpellini, proviene dalla formazione della scaglia rossa (cretaceo medio-eocene medio; aa.vv.1994) della serie umbro-marchigiana, presente lungo i versanti del m. subasio, il “monte” di assisi. lungo la brachianticlinale del m.subasio affiorano, infatti, le rocce della successione sedimentaria di età compresa fra il lias inferiore ed il miocene medio (passeri in aa.vv, 1994) rappresentate, tra le altre, dalla scaglia bianca e dalla scaglia rossa; mentre la prima è presente discontinuamente, la seconda si rileva sulla sommità e lungo il versante orientale del m. subasio (venturi & rossi, 2003) e il suo colore rosso/rosato ha conferito una inconfondibile connotazione all’aspetto di assisi. la città, noto centro internazionale della tradizione religiosa, possiede pertanto un “valore aggiunto” rappresentato dallo storico uso della roccia nelle sue mura, chiese, piazze, ecc., in una architettura fortemente legata al paesaggio geologico locale. stesso bi-cromatismo litologico (bianco-rosso) si riscontra anche nel materiale usato nella costruzione dei palazzi e dei monumenti-simbolo della vicina città di perugia (per perseguire l’alternanza del bianco-rosa, a perugia come ad assisi, al “rosa” della scaglia locale veniva, talora, affiancato anche il “rosso di verona”; fig. 15). 3. conclusioni tutti gli esempi riportati, rappresentano solamente alcune delle situazioni “litologico-archeologiche” presenti nel tessuto urbano di alcune città dell’umbria e dintorni, che raccontano processi e forme appartenenti ad un passato, geologicamente e morfologicamente, non sempre, molto lontano. le vicende geologiche e il conseguente modellato superficiale dei luoghi, infatti, hanno decisamente condizionato, non solo l’ubicazione dei siti urbani, ma anche la tipologia edilizia delle città che si è avvalsa, quasi sempre, dei materiali “autoctoni” che la storia geologica ha trasmesso, assegnando ai centri storici, contemporaneamente, un importante valore scientifico e culturale. tali valenze, purtroppo, rimangono sempre più spesso confinate alle strutture storiche, poichè la moderna ed uniforme tipologia edilizia tende, in genere, a spersonalizzare il “paesaggio storico-ambientale”, non permettendo più, almeno per un certo periodo storico (gli anni del boom edilizio), di riconoscerne il contesto territoriale. la conoscenza geologica e geomorfologica, tuttavia, del territorio attraverso anche una normale gita all’interno dei centri storici è una “pratica turistica” che andrebbe favorita, poiché consente la“percezione” e l’acquisizione di contenuti culturali non scontati e, talora, insospettati. (*) comunicazione orale del prof. giampiero poli – università di perugia) bibliografia accordi b. & moretti a. (1967) note illustrative della carta geologica d’italia, alla scala 1:100.000. foglio 131 foligno, servizio geologico d’italia, poligrafica & cartevalori. ercolano napoli, 61 pp. aa.vv.(1994) guide geologiche regionali.15 itinerari. appennino umbro-marchigiano. soc. geol. italiana, be-ma editore, 301 pp. bizzarri c. (1998) orvieto underground. betagamma editrice, 47pp. cattuto c. cencetti c.& gregori l. (1992) il pliopleistocene nell’area meridionale del bacino del f.tevere: possibile modello morfotettonico. studi geol. camerti, 1, p.103-108, 3ff, 1 tav.f.t. ca t t u t o c. gr e g o r i l., ra p i c e t t a s., bi z z a r r i c., giontella c. & stopponi s. (2002) gis e geoarcheologia in località campo della fiera presso orvieto (tr). atti della 6a conferenza naz. asita geomatica per l’ambiente, il territorio e il patrimonio culturale. 2, p. 705-714, 9ff. 277 a) b) fig. 15 l’acropoli perugina denuncia, attraverso i suoi monumenti-simbolo la litologia locale: la fontana maggiore (a) e la facciata della cattedrale di s.lorenzo (b). the acropolis of perugia, through its monuments, tell about the local lithology: the fontana maggiore (a) and the facade of s. lorenzo’s cathedral (b). la “memoria” geologico-geomorfologica in alcune città ... delcourt h.r. & delcourt p.a. (1988) quaternary landscape ecology: relevant scales in space and time. landscape ecology, 2, p.23-44. giacomelli l.& scandone r. (2002) vulcani e eruzioni. pitagora editrice bologna, 278 pp. gregori l. (2005) il lago trasimeno: dalla carta storica al dem, boll.ass. ital. di cartografia, n. 123-124, 69-95. gregori l., melelli l., rapicetta s. & taramelli a. (2005) principal geomorphosites in umbria region. il quaternario, vol. speciale a cura di piacente & coratza, geomorphological sites and geodiversity, 18, 1,p.93-101. gr e g o r i l.& tr o i a n i c. (2005) la cascata delle marmore (terni/umbria):storia ed evoluzione di un “geomorfosito”. boll. ass. italiana cartografia, 123-124, p. 69-95. jacobacci a., bergomi c., centamore e., malatesta a., malferrari n., martelli g., pannuzzi l.& zattini n. (1970) note illustrative della carta geologica d’italia, alla scala 1:100.000. fogli 115 “città di castello” 122 “perugia” 130 “orvieto”. servizio geologico d’italia. 151 pp. lotti b.(1926) descrizione geologica dell’umbria. mem. descrittive della carta geologica d’italia, 21, 320 pp., 65 ff., 6 tavv., 2 carte. melelli l. (2004) i dem derivati da sistemi radar:uno strumento per l'idenficazione dei conoidi alluvionali. atti della 8a conferenza naz. asita, 2, p.14451450,3ff. panizza m. & piacente s. (2003) geomorfologia culturale. pitagora editrice bologna, 350 pp. piacente s. & poli g. (2003) la memoria della terra-la terra della memoria, università degli studi di modena e reggio emilia-regione emilia e romagna, bologna, grafiche damiani, pp. 158 panizza m. & piacente s. (2005) geomorphosites: a bridge betwenn scientific research,cultural integration and artistic suggestion. il quaternario volume speciale a cura di piacente & coratza, geomorphological sites and geodiversity 18, 1, p. 3-10. pialli g., martini e. & sabatini p. (1978) contributo alla conoscenza della geologia del colle di orvieto. boll.soc. geol., 97, p. 103-114, 10ff. guzzetti f. & cardinali m.(1989) carta inventario dei movimenti franosi della regione dell’umbria ed aree limitrofe in: studio dei centri abitati instabili in umbria a cura di felicioni s. martini e. & ribaldi c., rubbettino editore, catanzaro, 1995, 418 pp. venturi f. & rossi s. (2003) subasio. origine e vicende di un monte appenninico.tipolito properzio snc, assisi/pg, 112 pp. 278 ms. ricevuto il 20 febbraio 2006 testo definitivo ricevuto il 31 ottobre 2006 ms. received: februaryr 20, 2006 final text received: octobe 31, 2006 l. gregori imp.coltorti& the growth of the chianti ridge: progressive unconformities and depositional sequences in the s. barbara basin (upper valdarno, italy) **mauro coltorti1, silvia ravani1 & federico verrazzani2 1dipartimento di scienze della terra, università di siena, via di laterina, 8 – 53100 siena; -coltorti@unisi.it, ravani@unisi.it 2libero professionista: kfeldspato@inwind.it abstract: m. coltorti et al., the growth of the chianti ridge: progressive unconformities and depositional sequences in the s. barbara basin (upper valdarno, italy). (it issn 0394-3356, 2007). the chianti ridge, elongated in a nw-se direction, separates the upper valdarno from the siena basins. it is made of macigno and scaglia toscana fms. belonging to the tuscan nappe that underlies the ligurian units. inside the upper valdarno basin three main synthems have been identified, separated by major unconformities; from the bottom: 1. castelnuovo synthem, subdivided into spedalino and meleto subsynthems, 2. montevarchi synthem and 3. bucine synthem. the spedalino subsynthem, that unconformably lies over the pre-pliocene bedrock, is made up of thin and laterally discontinuous coarse gravels. the meleto subsynthem, commonly referred to a lacustrine environment, is made of alluvial plain lithofacies, including channel, crevasse splay and swamp depositional systems where a taxodium forest developed and peat accumulated. close to the western margin of the basin these subsynthems are tilted up to 60°. the montevarchi synthem, mainly made of sands and gravels accumulated inside a wide braidplain, and lies unconformably over the previous units. this synthem is tilted eastward up to 20°. finally, the bucine synthem lies unconformably over the previuos synthems generating a fluvial terrace of the arno river. the two lower units date back to the early pliocene. in fact the meleto clays contain mammal remains that can be found in the triversa faunal unit (early villafranchian, late early middle pliocene) as well as in the ruscinian (early pliocene). they are also negatively magnetized and could correspond to the gilbert chron. palaeomagnetic investigations and the presence of aeolian sediments in the montevarchi synthem and cold pollen flora allowed its attribution to the middle and late pliocene. the relationships between the different synthems and the dominant unconformities coupled with thermochronological data recently obtained in the apennine ridge to the east (balestrieri et al., 2003) allow us to establish that the chianti ridge, after a major planation, became the eastern edge of a moderate relief (spedalino subsynthem) that was later transformed into a wide alluvial plain (meleto subsynthem). updoming tilted the previous units before the modelling of a second major unconformity that preceed the deposition of the montevarchi synthem. it is possible that during this period the valdarno was still connected to the siena basin to the west. a third major unconformity followed finally separating the two basins. these deformations occurred almost at sea level. during the early and middle pliocene, the apennine ridge to the east did not exist and the upper valdarno represented the western part of the peri-adriatic basin. the deepening of the drainage network is due to the generalised uplift that in the nearby areas started during the early pleistocene. finally the creation of the present-day apennine watershed was not gradual but very rapid in the geological time scale and started mostly during the early pleistocene. riassunto: m. coltorti et al., il sollevamento della dorsale del chianti: discordanze progressive e sequenze deposizionali nel bacino della s. barbara (valdarno superiore, italia). (it issn 0394-3356, 2007). la dorsale dei monti del chianti, orientata in direzione no-se, separa il bacino della valdarno superiore dal bacino di siena. essa è costituita dai termini più recenti della serie toscana (macigno e scaglia toscana) che sovrascorrono le unità liguri. nel bacino della valdarno superiore sono stati riconosciuti tre sintemi delimitati da importanti superfici di discordanza, dal basso verso l’alto: 1, sintema di castelnuovo, suddiviso nei subsintemi di spedalino e di meleto; 2, sintema di montevarchi; 3, sintema di bucine. il subsintema di spedalino, che giace in discordanza sul substrato pre-pliocenico, è costituito da ghiaie grossolane di modesto spessore e lateralmente discontinue. il subsintema di meleto, generalmente interpretato come un sistema deposizionale lacustre, è caratterizzato da litofacies di pianura alluvionale, differenziate in vari sistemi deposizionali (canali, tracimazioni, paludi, ecc.) dove si depositavano torbe e si sviluppava una foresta a taxodium. nei pressi del margine occidentale del bacino entrambi questi subsintemi sono piegati fino a 60°. il sintema di montevarchi, costituito prevalentemente da sabbie e ghiaie deposte in un’ampia pianura a canali intrecciati, giace in discordanza sulle unità precedenti. questo sintema è piegato verso est fino a 20°. infine, il sintema di bucine giace in discordanza sui precendenti sintemi generando un terrazzo fluviale del fiume arno. le due unità inferiori sono datate al pliocene inferiore. infatti le argille di meleto contengono faune a mammiferi che possono essere attribuite sia al villafranchiano inferiore (tardo pliocene inferiore – pliocene medio, unità di triversa), sia al rusciniano (pliocene inferiore). questi subsintemi sono magnetizzati negativamente e sono attribuiti all’evento di gilbert. le indagini paleomagnetiche, la presenza di depositi eolici e le associazioni polliniche fredde hanno permesso di attribuire il sintema di montevarchi al pliocene medio e superiore. le relazioni esistenti tra i sintemi individuati e le varie discordanze, unitamente ai dati termocronologici, ottenuti recentemente nella dorsale appenninica a est (balestrieri et al., 2003) hanno permesso di stabilire che la dorsale del chianti, dopo un importante spianamento è diventata il margine orientale di un modesto rilievo (subsintema di spedalino) e più tardi un’ampia pianura alluvionale (subsintema di meleto). il sollevamento della dorsale ha piegato le unità precedenti prima del modellamento di una seconda discordanza che ha preceduto la deposizione del sintema di montevarchi. è possibile che durante questo periodo la valdarno fosse ancora connessa con l’adiacente bacino di siena posto più a ovest. successivamente si modella una terza principale discordanza che separa nettamente i due bacini. queste deformazioni avvenivano all’incirca al livello del mare. durante il pliocene inferiore e medio la dorsale appenninica ad est non emergeva e il valdarno superiore rappresentava il settore occidentale del bacino peri-adriatico. l’approfondimento del reticolo di drenaggio è dovuto al sollevamento generalizzato che, nelle aree limitrofe, è iniziato durante il pleistocene inferiore. infine, la creazione dell’attuale spartiacque appenninico non è stata graduale ma molto rapida, a scala dei tempi geologici, ed è iniziata soprattutto durante il pleistocene inferiore. keywords: progressive unconformity, synthem, stratigraphy, facies analysis, chianti ridge, valdarno, apennines, italy. parole chiave: progressive unconformity, sintema, stratigrafia, analisi di facies, dorsale del chianti, valdarno, appennino, italia. il quaternario italian journal of quaternary sciences 20(1), 2007 67-84 ** lavoro presentato al convegno “il sollevamento quaternario nella penisola italiana e nelle aree limitrofe” (roma, 6-8 febbraio 2006) 68 m. coltorti, s. ravani & f. verrazzani 1. introduction the basins on the tyrrhenian side of the italian peninsula are the site of a major controversy because their origin has been associated to ongoing tectonics during the miocene and pliocene. in the past, research was mostly concentrated on the general setting of the basins and their main subdivisions; few investigations were devoted to facies analysis or to their relationship with the nearby ridges that represent the results of the same dynamics. this is probably due to the fact that at the summit of the ridges only erosional features are still preserved. in this paper, we investigate the western side of the upper valdarno basin, one of the most famous neogene-quaternary basins in the northern apennines, because it contains a large number of sites with villafranchian mammal fauna (azzaroli, 1977; gliozzi et al., 1997). in this area, inside the santa barbara peat quarry, the oldest sediments of the basin crop out. there are extensive outcrops and a series of boreholes1 that reach the bedrock evidencing the geometry of the erosional surface at the base of the filling and that of the peat layers. we also investigated the different unconformity bounded stratigraphic units (ubsu) and their sedimentological characteristics and the architectural elements. this allowed us to establish the modifications that occurred in relation with the ongoing tectonics. using all the scarce chronological elements, we tried to associate the changes that affected the basin with the uplift of the ridge, that was one of our main goals. we use a multidisciplinary approach involving geology, geomorphology and facies analysis which gives the best possibilities of understanding how and when the basin and nearby ridge were generated, the dynamics that affected the area and the changes that led to the creation of the present-day landscape. we are going to demonstrate that, contrary to what was previously hypothesised these ridges are the result of folding and not of normal faulting. moreover these movements did not create topography during the pliocene, and the present day setting is mostly the result of differential erosion activated after the movement of generalised uplift that affected the apennines coupled with high angle normal faulting along the tyrrhenian side since the late early pleistocene. 2. the geologic and stratigraphic background the upper valdarno, situated approximately 30 km to the se of florence, was considered a graben or half-graben (trevisan, 1952; nardi, 1961; elter et al., 1975; eva et al., 1978; mariani & prato, 1988; patacca et al., 1990; bertini et al., 1991; lazzarotto & liotta, 1991; sagri 1991; billi et al., 1991; martini & sagri, 1993; bossio et al., 1995). it is characterised by a relatively gently sw margin (chianti ridge) and by a steep ne side (pratomagno ridge) where the main fault system is located. to the w the chianti mountains separate it from the siena basin. it is elongated about 35 km in a nw-se direction with a maximum width of 15 km (fig. 1, 2). 1 thanks to enel fig. 1 a. schematic structural map of the main thrust fronts in the area (from aavv, 1982 modified), fu: cervarola-falterona unit front; tu: tuscan unit front; mtu: mid-tuscany metamorphic unit. b. geological sketch map of the siena basin, chianti mountains, upper valdarno basin and pratomagno ridge. 1: alluvial holocene deposits, 2: pleistocene deposits, 3: marine clay, silty-marly clays of the siena basin (pliocene), 4: marine conglomerates and sandstones of the siena basin (pliocene), 5: santa barbara basin (early-middle pliocene), 6: ligurian units, 7: macigno fm., 8: scaglia toscana fm., 9: cervarola falterona fm., 10: thrust and reverse faults; 11: buried thrust and reverse faults; 12: high-angle normal faults; 13: buried normal faults; 14: lowangle normal faults; cs: castelnuovo dei sabbioni, si: siena. the rectangle shows the studied area. a. schema strutturale dei principali thrust nell’area in esame (aavv, 1982 modificato), fu: unità cervarola-falterona; tu: unità toscane; mtu: unità metamorfiche medio-toscane. b. carta geologica del bacino di siena, monti del chianti, bacino del valdarno superiore e dorsale del pratomagno. 1: depositi alluvionali olocenici, 2. depositi pleistocenici, 3. argille, argille siltoso-marnose marine del bacino di siena (pliocene), 4. conglomerati e sabbie marine del bacino di siena (pliocene), 5. bacino della s. barbara (pliocene inferiore-medio), 6. unità liguri, 7. macigno, 8. scaglia toscana, 9. unità cervarolafalterona, 10. thrust e faglie inverse, 11. thrust e faglie inverse sepolte, 12. faglie normali ad alto angolo, 13. faglie normali sepolte, 14. faglie normali a basso angolo; cs: castelnuovo dei sabbioni, si: siena. il rettangolo indica l’area studiata. 69the growth of the chianti ... fig. 2 geological sketch map of the studied area. 1: holocene fluvial deposits, 2: bucine synthem (late pleistocene), 3: montevarchi synthem (early pliocene-early pleistocene), 4: meleto subsynthem (early-middle pliocene), 5 spedalino subsynthem (early-middle pliocene). bedrock:6: ligurian units (claystones, limestones and marls), 7: macigno fm., 8: scaglia toscana fm., 9: mine area, 10: section tracks; 11: reference topographic points; 12: fault; 13: normal strike and slip; 14: reverse strike and slip; 15: stratigraphic section tracks. cs: castelnuovo dei sabbioni, me: meleto, sb: santa barbara, sda: san donato in avane, ga: gaville, cm: cavriglia monastero, po: poggio secco. schema geologico dell’area studiata. 1: depositi fluviali (olocene), 2: sintema di bucine (pleistocene superiore), 3: sintema di montevarchi (pliocene superiore-pleistocene inferiore), 4: subsintema di meleto (pliocene inferiore-medio), 5: subsintema di spedalino (pliocene inferiore-medio). substrato: 6: unità liguri (argille, calcari e marne), 7: macigno, 8: scaglia toscana, 9: area miniera, 10: traccia sezioni, 11: punti quotati, 12: faglie, 13: strati diritti, 14: strati rovesci; 15: tracce delle sezioni stratigrafiche. cs: castelnuovo dei sabbioni, me: meleto, sb: santa barbara, sda: san donato in avane, ga: gaville, cm: cavriglia monastero, po: poggio secco. 70 the chianti ridge is made by a stack of different tectonic units (elter & sandrelli, 1995; bonini, 1999). the non-metamorphic tuscan nappe is the lowest and it is represented by folded rocks of the macigno sandstones (late oligocene – early miocene) and the scaglia toscana calcarenites, shales and marly limestones (middle cretaceous oligocene). in the eastern side of the chianti ridge, large olistostromes coming from the ligurian and sub-ligurian units (complesso di canetolo, m. morello unit) were deposited inside the macigno fm. (merla,1969; castellucci & cornaggia, 1980; lazzarotto & liotta, 1991; bonini, 1999). similar olistostromes, dispersed in the turbiditic series of the northern apennines, would indicate submarine landslides connected with the progressive migration of the tectonic units towards the foredeep (abbate & sagri, 1981; pini, 1999 and ref. therein). however, to explain the geometry of the different lithological units castellucci & cornaggia (1980) inferred the presence of a series of overturned folds. in the ne margin of the basin, the tuscan unit tectonically overlies, along w-dipping thrust fronts, a thick turbiditic sandstone succession belonging to the cervarola-falterona unit (me r l a & ab b a t e, 1967; abbate, 1983; albianelli et al., 1995; bonini, 1999). the various tectono-sedimentary units are the result of the eastward overthrusting of the terrains belonging to the westernmost palaeogeographic domains (elter et al., 1975; ricci lucchi, 1986; bertini et al., 1991; patacca et al., 1990; barchi et al., 1998; finetti et al., 2001). later on, the tuscan and cervarola units were overlain along low angle e-dipping faults by the allochthonous ligurian units, mostly made up of clays, limestones and marls (m. morello unit, complesso caotico) (merla & abbate, 1967; abbate, 1983; boccaletti & coli, 1983; decandia et al., 1993). this rootless tectonic unit (locardi, 1982) was detached in correspondence to the less resistant formations and, at least the more external part is generally considered the result of gravity tectonics known locally as “gravitational flows” (i.e. marecchia valley; ruggieri, 1970; veneri, 1986). in fact, the thrusting along the fronts was compensated by a series of detachments in the area now occupied by the ligurian sea. today, the chianti ridge constitutes an antiform with the tuscan unit at the core and ligurian units cropping out in the sw and ne side of the basin. the western margin of the valdarno basin corresponds to the eastern side of this antiform. the evolution of the intermontane basins, including the upper valdarno, is actually very debated. a group of authors interpreted them as graben-like features, created on the rear of the thrust fronts (elter et al., 1975; martini & sagri, 1993; barberi et al., 1995). their origin should be linked to the migration of the apennine chain-foredeep system and therefore their activation and filling should be progressively more recent moving from w to e. many authors associated this migration to a typical subductional model (malinverno & ryan, 1986; patacca et al., 1990; doglioni, 1991). in this model, the extensional movements controlled the fluvial-lacustrine sedimentation. the older extensional basins in the onshore tyrrhenian side would be generated during tortonian-messinian times (azzaroli & lazzeri, 1977; abbate, 1983; bernini et al., 1990 see ref. therein; billi et al., 1991; sagri, 1991; bossio et al., 1995; sagri & magi, 1992; benvenuti, 1993; martini & sagri, 1993; albianelli et al., 1995). more recently, at least four main regional unconformities (messinian, early pliocene, late pliocene, early-middle pleistocene), related to syndepositional events, have been documented (bernini et al., 1990, boccaletti & sani, 1998, boccaletti et al., 1999) and associated by the same authors to the “compressional” style of basin genesis (boccaletti et al., 1995; c o l t o r t i & p i e r u c c i n i , 1997a; 1997b; calamita et al., 1999). lazzarotto & liotta (1991) had already documented the presence of folds inside the fluvial-lacustrine deposits but it was supposed to have only a local significance in an extensional context. finetti et al. (2001, and ref. therein) considered these basins as “perched basins”, quite synonymous of “thrust-top” and “piggy back basins” (grasso & butler, 1991). on the other hand, coltorti & pieruccini (1997a; 1997b), calamita et al. (1999) and, more recently, argnani et al. (2004) attributed these deformations to the surface response of the activity of low-angle e-dipping normal faults. the latter authors agree that the high angle normal faults that today delimit the eastern border of the basin are the result of extensional movements active since the end of the early pleistocene. during our field work, we recognised a series of abrupt contacts between different lithologies that are difficult to explain except with the occurrence of a fault zone with various fault planes that mark the contact between different terrains (figs. 2, 3). in our interpretation, all the tectonic contacts represent e-dipping low angle faults that affected both the tuscany and ligurian terrains. this wide fault zone (fig. 3) is located on the northern continuation of one of more important detachments of the apennine area: the alto-tiberina fault (barchi et al.,1998; boncio et al., 1998; boncio & lavecchia, 2000). although bonini (1999) attributed the evolution of the valdarno basin to the activity of the thrust front along the western side of the chianti ridge, and especially at the contact between tuscan and ligurian units, we collected any evidences that could confirm this hypothesis. 3. the plio-pleistocene deposits the sedimentary filling of the upper valdarno basin is made up of continental sequences attributed to the middle pliocene up to the pleistocene (merla, 1949; abbate, 1983; albianelli et al., 1997; albianelli et al., 2002; napoleone et al., 2003). the contact between the pre-pliocene bedrock and the plio-pleistocene deposits is an abrupt unconformity. inside the filling three stratigraphic units separated by angular unconformities have been recognised by the previous authors (sestini, 1936; azzaroli & lazzeri, 1977; abbate, 1983; billi et al., 1991; bertini et al., 1991; lazzarotto & liotta, 1991; martini & sagri, 1993). more recently, they have been grouped in synthems (sagri & magi, 1992; benvenuti, 1993) and supersynthems (boccaletti et al., 1995; ghinassi & magi, 2004) indicative of three depositional cycles (fig. 4). from the oldest they are: 1, castelnuovo; 2, montevarchi and 3, monticello-ciuffenna. the m. coltorti, s. ravani & f. verrazzani fig. 3 geologic sections through the s. barbara basin as mapped in fig.2. 1: holocene fluvial deposits, 2: bucine synthem, 3: montevarchi synthem, 4: meleto subsynthem, 5 spedalino subsynthem, 6: claystones, limestones and marls (ligurian units), 7: macigno fm., 8: scaglia toscana fm., 9: mine area, 10: fault, ga: gaville; me: meleto, sb: santa barbara, cs: castelnuovo dei sabbioni, l: lignite bank. sezioni geologiche attraverso il bacino della s. barbara così come indicate in fig.2. 1: depositi fluviali olocenici, 2: sintema di bucine, 3: sintema di montevarchi, 4: subsintema di meleto, 5: subsintema di spedalino, 6: argille, calcari e marne (unità liguri), 7: macigno fm., 8: scaglia toscana fm., 9: miniera, 10: faglia, ga: gaville; me: meleto, sb: santa barbara, cs: castelnuovo dei sabbioni, l: banco di lignite. 72 castelnuovo synthem was further subdivided into three units, from the bottom: spedalino gravels and sands, meleto clays and s. donato sands, while the montevarchi synthem includes the terranuova silts, ascione clays and oreno silts and sands (lazzarotto & liotta, 1991; magi & sagri, 1996; bertini, 2001; napoleone et al., 2003; ghinassi & magi, 2004). we continued to use this name for the montevarchi synthem (fig. 4) because we prefer not to proliferate names in the scientific literature. however, it must be stated that this unit has never been described in detail and a type sequence does not exist. moreover we changed the base of the sequence that, after our investigation, is marked by a major unconformity not recognised in the other areas. it separates the castelnuovo from the montevarchi synthem and the s. donato sands belongs to the latter (fig. 4). these last sediments should be interlayered with coarser sediments interpreted as fan delta deposits fed from the east (penna gravels, casa quercia gravels and sands and borro cave sands). along the sw margin of the basin this synthem also includes the montecarlo sands and silts and white aeolian sands (rena bianca sands) interlayered with fluvial sands in the areas close to the alluvial systems located to the west (magi & sagri, 1996; bertini, 2001; ghinassi & magi, 2004). the aeolian sands seem to overlie discontinuously with the s. donato sands (bertini, 2001; ghinassi & magi, 2004; ghinassi et al., 2004). finally the monticello-ciuffenna synthem is made of fluvial deposits (laterina gravels, levane sands and latereto silts) and alluvial fan deposits (loro ciuffenna gravels, tasso sands and pian di tegna silts) (benvenuti, 1993; albianelli et al., 1995). this synthem corresponds with bucine synthem (fig. 4) but this name is here preferred because it was used first in literature (merla & abbate, 1967; azzaroli & lazzeri, 1977; lazzarotto & lotta, 1991). the relationships between the erosional boundary surfaces located: 1. at the base of the sequence; 2. at the base of the montevarchi synthem; 3 at the base of the bucine synthem, generate a progressive unconformity that testifies that the chianti ridge underwent uplift movements while the basin was sinking, hosting a “fluvial-lacustrine sedimentation” (boccaletti et al., 1995; bonini, 1999). a detailed sedimentological analysis of the neogene-quaternary deposits outcropping in the upper valdarno basin was carried out to identify: 1, the facies associations and the architectural elements and, 2, the depositional paleo-environment. in fact, except for some general observations on the main lithological units (abbate, 1983; billi et al., 1991; benvenuti, 1993; martini & sagri, 1993), an exhaustive sedimentological study was made only for the late pliocene aeolian sediments (ghinassi & magi, 2004). our sedimentological analyses were made adopting the miall (1985; 1996) classification. the facies analysis and the different lithofacies associations led to the recognition of many architectural elements used to distinguish between the depositional systems. in the present work three synthems have been recognised, bounded by unconformities partially not consistent with those identified by the previous authors. in fact the castelnuovo synthem corresponds only in part with the basal sequence recognised by the previous authors (fig. 4) because it is made only by the two basal units (spedalino gravels and sands, meleto clays). nevertheless we decided not to create new names in order to avoid a proliferation of new synthems in the geological literature. the contact between the two units is never visible in outcrop and a clear unconformity between the two basal units is not recognisable although we cannot exclude it. however, the facies association changes abruptly. the sediments cropping out in the meleto area (meleto clays of previous authors) have been here considered a subsynthem. it must be pointed out that the textural description is wrong because the clays are subordinate to the sands. the castelnuovo synthem is unconformably overlapped by the montevarchi synthem, that is overlaid by the bucine synthem. at least in the study area there are no facies variations, inside the montevarchi synthem, that should be used for a further subdivision as the previous authors have done in the montevarchi area (sagri & magi, 1992; ghinassi & magi, 2004). in particular, the sediments belonging to each synthem can also lie directly on the bedrock (figs. 2, 3). fig. 4 synthesis of the stratigraphic reconstruction of various authors. sintesi della stratigrafia ricostruita da vari autori. m. coltorti, s. ravani & f. verrazzani 3.1 castelnuovo synthem as mentioned above it is difficult to establish the relationships between the older deposits and if they should be considered a synthem or a subsynthem. in fact, the older is very thin and only locally preserved and the contact with the overlying sediments is never visible in the field. moreover, they are continental deposits where erosional boundaries are common. 3.1.1 spedalino subsynthem the subsynthem is mostly made up of gravels and sands. short stratigraphic sections have been observed at the contact with the macigno fm. the most important sections are located to the north of gaville and near san donato in avane (figs. 2, 7, 8). in the western sector of the basin, close to the chianti ridge, the unconformity at the base of the gravels as well as the overlying layers dip ca. 40°-70° to the ne while to the e they become sub-horizontal (fig. 3). albianelli et al. (2002) mentioned a negative magnetic field of layers inside the spedalino subsynthem but does not show where the sequence was made. on the other hand, albianelli et al. (1997) and napoleone et al. (2003) have clearly shown that a magnetic signal was found in the lower part of the meleto clays. the dating of the base of the unit was therefore obtained extrapolating a constant sedimentological rate. these circular arguments could hide a much older age for the spedalino gravels especially if a major unconformity was to be located at the top of the sequence. facies analysis two stratigraphic sections have been investigated in detail (s1 and s2; figs. 2, 7). the deposits are made up of clast-supported cross-bedded or massive rounded gravels and pebbles (gt and gm) well sorted in places. they generate massive layers up to 3 m thick (fig. 7). the gravels are medium to coarse-grained up to 100 cm in size (s2). the matrix is scarce. the composition is exclusively arenaceous coming from macigno fm. occasionally soft clasts are present. rare lenses of cross-bedded stratified sands are also present (st) (s1; fig. 7). interpretation similar sediments are found in coarse gravelly depositional systems such as a pedemountain stream, braided channels or in proximal alluvial fan deposits. the good sorting of some coarse gm layers suggests the presence of armoured beds that favours a pedemountain stream environment. the gt and thin lenses of st lithofacies are consistent with the same environment. the lateral absence of this unit could suggest that it fills a palaeo-valley cut into the bedrock. the river was located close to a relief and fed by rocks belonging to the macigno fm. 3.1.2 meleto subsynthem it is made by fine sediments, rich in lignite layers. in boreholes, the clays are up to 250 m thick. the most extensive outcrops are located close to the san donato quarry where ca. 15÷20 m thick sequences have been described (figs. 2, 7, 8). these sediments contain remains of mammal bones of tapirus arvernensis, ursus minimus, dicerorhinus sp., leptobos sp. and anancus arvernensis, related to the triversa faunal unit (borselli et al., 1980; de giuli et al., 1983; benvenuti et al., 1995; albianelli et al., 1997), attributed to the early villafranchian. however, a similar association is also found in the ruscinian (early pliocene) (fejfar, 2001). the palinological analyses recognised an association of tropical (taxodiaceae, lauraceae, nyssa, engelhardia, symplocos, ecc.) and temperate taxa (quercus, carpinus, liquidambar, carya, zelkova, populus, acer, betulla, fagus, etc.) (bertini & roiron, 1997) that indicate warm humid climatic conditions favourable to the development of forests and swamps. albianelli et al. (2002) and napoleone et al. (2003) established a reverse polarity for the lowermost part of the sequence and attribute it to the k-interval gauss (c2an.1r) suggesting an age of 3.1 ma for a lignite layer close to the base of the sequence. however, the chronostratigraphic setting is based on the supposed middle pliocene age of the triversa unit, that as previously stated is uncertain. it is also based on the assumption of a constant sedimentation rate and does not consider that the sequence, as we describe in the following paragraphs, is not continuous and is split in two by a major unconformity located between the castelnuovo and the montevarchi synthems. therefore, there is no base for the application of the “count from the top” method as utilised by napoleone et al. (2003). moreover, the whole sequence is clastic and contains a large number of channels that constitute further discontinuities at a local scale. therefore, paleomagnetic investigations can only be used to state that this unit is older than 3.1 ma. facies analysis four stratigraphic sections crop out in the s. barbara and in the s. donato quarries (s3-s6; figs. 2, 7). the meleto subsynthem is mainly made up of grey massive or slightly laminated silty clays (fm, fl), containing wood remains, branches, leaves and pine-cones. these lithofacies are interlayered with thin layers of fine to coarse trough or planar cross bedded sands (st and sp lithofacies respectively), up to 30 cm thick (s5; fig. 7). rarely coarse and medium-grained sands (st, sp), up to 180 cm thick, are present and contain wood fragments (branches and leaves) (s4; fig. 7). in particular, in s4 section a 6 m thick lignite bed has been observed containing thin layers (up to 20÷30 cm thick) of fine to medium grained trough cross bedded sands (st). the rooted parts of many tree trunks in a standing position have also been observed (s3; fig. 7). thicker lignite beds are also well known at depth and were extensively quarried. smaller cascade folds have been observed close to the bedrock. boreholes for lignite exploitation revealed the existence of a narrow synform close to the mountain slope bordered to the east by a minor antiform (fig. 3). the latter is made up of folded sandstones and has been named meleto anticline by bonini (1999). interpretation most of the fine-grained sediments (fm and fl lithofacies association) are overbank deposits (architectural element ff), developed from overbank sheet flow into a large alluvial plain characterised by different subenvironments (channels, crevasse, swamps, etc.). the peat represents the accumulation of the vegetation in the floodplain where a taxodium forest developed from 73the growth of the chianti ... time to time. the thinner sandy lithofacies (st, sp) represents a crevasse channel (architectural element cr) breaking the main channel margin. the progradation from crevasse channel into floodplain creates crevasse splay deposits (cs) that periodically affected the floodplain. these deposits are characterised by st and fl lithofacies associations. the architecture is coherent with the model 6 (sandy, mixed load meandering rivers) of miall (1985). 3.2 montevarchi synthem the main sections are located inside the s. donato quarry, next to village of meleto, and inside the santa barbara area (figs. 2, 5, 7, 8). close to the study area, in the sw sector of the valdarno basin, at the top of the supposed coheval montevarchi succession, finegrained levels rich in pollen assemblages have been encountered interlayered with aeolian deposits (rena bianca sands, fig. 4). the basal part of the rena bianca sequence is characterised by cold and humid climatic conditions with dry moderate oscillations (bertini, 1994; albianelli et al., 1995). the progressive cooling is testified to by the increase of fagus and picea (bertini & roiron, 1997). the previous authors did not notice the unconformity and included this unit inside the montevarchi synthem. it is related to the late pliocene – early pleistocene interval (billi et al. 1991; bossio et al., 1992; albianelli et al.,1995), because of the finds of late villafranchian faunas (azzaroli, 1977; de giuli, 1983; azzaroli, 1984; benvenuti, 1993). in particular, the base of the rena bianca sands is attributed to ca. 2,58 ma (gelasian) based on paleomagnetic investigations (albianelli et al., 2002; napoleone et al., 2003). the deposition of the aeolian sands occurred during an arid event inside the global climatic deterioration of this period (bertini & roinor, 1997; ghinassi et al, 2004). again, albianelli et al. (2002) and napoleone et al. (2003) suggested an age of 2.64 ma for the top of the meleto subsynthem, but as previosuly stated, they used a constant sedimentation rate between two paleomagnetic intervals the lowermost being located below a major unconformity. facies analysis eight sections (s7-s14) have been investigated (figs. 2, 7). the bottom part of the synthem is mainly characterised by fine to coarse trough or planar crossbeds (st and sp respectively) that show a marked lateral facies variation. load-cast structures are sometimes present. the sands are generally alternated with rich organic matter, grey massive or slightly laminated silty clays, a few cm thick (fm, fl). the lack of sedimentary structures is probably due to strong bioturbation. wood remains are common. moving upwards, there are trough crossbedded gravels (gt) interlayered with fine to coarse trough crossbeds (st) and horizontal laminated sands (sh). rarely ripple cross-lamination is present (sr). moreover rich organic centimetric beds are common (c), although wood remains are generally also scattered inside the sandy lens. the base of the gravels is erosional and marked by pebbles in a scarce sandy matrix. the clasts are generally well rounded and up to 10 cm in diameter. they are mainly derived from the macigno sandstones. however, near poggio secco, some clasts with an orthogneiss composition (f. talarico, pers. com.) have been recognised. the finding of metamorphic clasts, and in particular of “porphiric aplite” whose easternmost outcrop is actually the elba island, is noticed in numerous peri-tyrrhenian basins (tongiorgi & tongiorgi, 1964; bossio et al., 1995). orthogneiss clasts have also been recognised inside the macigno fm. in the chianti mts. (ferrini & pandeli, 1983). interpretation gravelly (gt) and sandy lithofacies (st, sh, sr) are typical of a fluvial channel (ch architectural element; miall, 1985). the tabular gravelly layers identify gravel bars or bedforms (gb architectural element) that are commonly interbedded with sandy bedforms (sb architectural element). the fine-grained lithofacies associations are deposited into the alluvial plain from overbank sheet flows (ff architectural element) and can also fill abandoned channels. these elements are commonly interbedded with sb architectural elements. fine organic sediments are also commonly deposited in the ponds and swamps inside the alluvial plain. sometimes crevasse splays (cs) can spread from crevasse channels into floodplains, interrupting the sedimentation of overbank fines (ff). the sedimentary architecture is typical of a wide alluvial plain with meander belts that 74 fig. 5 s. donato sands belonging to the montevarchi synthem. sabbie di s. donato appartenenti al sintema di montevarchi. m. coltorti, s. ravani & f. verrazzani turn upwards into a braidplain. the fluvial style suggests a gravel-sand or a gravelly meandering river (model 5 and model 6; miall,1985). the orthogneiss clasts come from the erosion of the macigno fm. located to the w. a main provenance from sw for the s. donato sands was also obtained with paleocurrent measurements by albianelli et al. (1995) and ghinassi & magi (2004). 3.3 bucine synthem the sections investigated (s15 and s16) are located near the village of gaville (fig. 2, 6, 7, 8). these are mainly gravels up to 15÷20 m in thickness (fig. 7). they constitute the top of a terrace and there are vertical escarpments (locally named “balze”) that represent the rim of the terrace. the summit of the terrace ranges between 290 m upstream in the castelnuovo dei sabbioni area to 240÷250 m near cavriglia, downstream. the longitudinal slope of the terrace was ca. 0,7%. these deposits contain faunas attributed to the middle-late pleistocene or to the end of the early pleistocene (borselli et al., 1980; de giuli, 1983; benvenuti, 1993; albianelli et al., 1995). in this work we suggest a late pleistocene age for the topmost unit because of its morpho-pedostratigraphic characteristics. in fact, the unit is: 1, the last deposit before the post-glacial incision that led to the present-day setting of the valley and there are no other wide terraces located at minor elevations; 2, the top of the terrace is not weathered by rubified soils with bt or bts profiles, typical of the mis 5 interglacial (coltorti & pieruccini, 2006). this synthem is apparently not deformed. facies analysis the deposits are characterised by clast-supported trough and planar cross-bedded gravels (gt and gp respectively), with a scarce sandy matrix. the clasts are well-rounded or sub-rounded and a sandstone composition predominates. their dimensions range from a few cm up to 20 cm. rarely fine to coarse trough crossbedded or massive sands (st and sm respectively) and silts (fm) up to 30 cm thick are present. the contact with gravels is clearly erosive. in the s15 section the unconformity between the castelnuovo and bucine synthems can be observed. in this sector of the basin the bucine gravels overlie the castelnuovo synthem made up of massive sand (sm) and massive organic rich silts (fm). interpretation the association of the gt and gm lithofacies and the tabular layers characterise gravel bars and bedforms (gb architectural elements: miall, 1985) generating a multilayer infilling. both lithologic, and textural features and lithofacies association are typical of a gravelly braidplain that could belong to the fluvial depositional system of the palaeo-arno river and its tributaries (model 2; miall, 1985). migrating channels and lateralaccretion macroforms (la architectural element) suggest the local onset of a wandering system (model 4; miall, 1985). the gradient of the top depositional surface gently dipping towards the central part of the valley in the area closer to the slope suggests the existence of a series of coalescent alluvial fans. 4. the evolution of the western side of the valdarno basin the beginning of the evolutionary history of the basin is marked by a major unconformity (fig. 9a). it allows us to separate pre-pliocene from plioquaternary tectonic movements. this unconformity cuts the thrust of the tuscan unit over the cervarola unit as well as the detachment at the base of the ligurian units. in fact, the early pliocene sediments lie unconformably over all these tectonic units. this confirms that a large amount of shortening and the later collapse of the ligurian units occurred previous to the early pliocene. it is worth mentioning that, around 5 ma an important rock uplift is recorded with thermochronologic analysis in the apennines to the e of the valdarno basin (abbate et al., 1994; balestrieri et al., 2003). 75 fig. 6 gravel deposits belonging to the bucine synthem cropping out north-east of poggio secco (see also fig.2). depositi ghiaiosi appartenenti al sintema di bucine affioranti a nord-est di poggio secco (cfr. fig.2). the growth of the chianti ... 76 f ig . 7 – s tr a ti g ra p h ic s e c ti o n s re la te d t o p o rt io n s o f th e r e c o g n is e d s yn th e m s in si d e t h e s . b a rb a ra b a si n : s p e d a lin o s u b sy n th e m ( s 1 a n d s 2 ); m e le to s u b sy n th e m ( s 3 t o s 6 ); m o n te va rc h i sy n th e m ( s 7 t o s 1 4 ) a n d b u c in e s yn th e m ( s 1 5 a n d s 1 6 ). t h e t h ic kn e ss o f th e s e c ti o n s is in m e te r. m : m u d , s: s ilt , s : sa n d a n d g : g ra ve l. t h e li th o fa c ie s c o d e s a re r e la te d t o f a c ie s c la ss ifi c a ti o n o f m ia ll (1 9 9 6 ). s e zi o n i s tr at ig ra fic h e r e la ti ve a p o rz io n i d e i i n te m i r ic o n o sc iu ti n e l b ac in o d e lla s . b ar b ar a: s u b si n te m a d i s p e d al in o ( s 1 ; s 2 ); s u b si n te m a d i m e le to ( s 3 s 6 ); s in te m a d i m o n te va rc h i ( s 7 s 1 4 ) e s in te m a d i b u c in e ( s 1 5 ; s 1 6 ). l o s p e ss o re d e lle s e zi o n i è e sp re ss o i n m e tr i. m : fa n g o , s: l im o , s : sa b b ia e g : g h ia ia . i c o d ic i d e lle l it o fa c ie s so n o r e la ti vi a llo s c h e m a c la ss ifi c at iv o d i m ia ll (1 9 9 6 ). m. coltorti, s. ravani & f. verrazzani 77 f ig . 8 s tr a ti g ra p h ic s e c ti o n s re la te d t o t h e r e c o g n is e d s yn th e m s in si d e t h e s . b a rb a ra b a si n : a . s p e d a lin o s u b sy n th e m , b . m e le to s u b sy n th e m , c . m o n te va rc h i s yn th e m , d . b u c in e s yn th e m . t h e f a c ie s a re o f m ia ll (1 9 9 6 ). s 1 -s 1 6 m a rk t h e r e la ti ve p o si ti o n o f th e p o rt io n s o f th e s tr a ti g ra p h ic s e c ti o n s re la te d t o f ig . 7 . s e zi o n i s tr a ti g ra fi c h e s in te ti c h e r e la ti ve a i s in te m i r ic o n o sc iu ti a ll’ in te rn o d e l b a c in o d e lla s . b a rb a ra : a . su b si n te m a d i s p e d a lin o , b . su b si n te m a d i m e le to , c . si n te m a d i m o n te va rc h i, d . si n te m a d i b u c in e . l e f a c ie s so n o r e la ti ve a llo s c h e m a d i c la ss if ic a zi o n e u ti liz za to d a m ia ll (1 9 9 6 ). s 1 -s 1 6 i n d ic a n o l a p o si zi o n e r e la ti va d e lle p o rz io n i d e lle s e zi o n i st ra ti g ra fi c h e a n a liz za te e r e la ti ve a lla f ig .7 . the growth of the chianti ... these authors suggest that the erosion of a cover up to 5.000 metres thick affected the ligurian units. an important erosion of the ligurian terrains is documented in the area because these terrains are completely missing along the chianti ridge as well as in many surrounding areas. however, in the investigated area, there is no evidences that the ligurian terrains could ever have reached such a thickness. because the base of the sequence is older than 3.5 ma the best place where this erosional event could be recorded is the major unconformity at the base of the filling. rather than explaining the cooling event with uplift followed by denudational process of 5 km of rocks, we suggest that the unusual very rapid erosion was partly associated with the delamination created by the detachment of the ligurian units. a later important planation processes at the beginning of the pliocene is to be added to this event. the origin of this planation is difficult to establish. coltorti & pieruccini (1997a; 1997b; 2002) suggested that in later times, a plain of marine erosion, preserved as a planation surface, was modelled across the apennines as a result of a major transgression during the late early pliocene. we suggest that a similar process could be responsible for most of the erosion associated with the older unconformity . it could correspond to the effects of the zanclean transgression, again a major and long lasting event, that created a major unconformity in continental and marine sequences all around the mediterranean. usually, the sequence stratigraphy suggests that a major unconformity is not modelled during a transgression but during a regression. in our opinion when the sea level drops in correspondence with a cold climate the rivers are overcharged of sediments and do not have the energy to carve an erosional surface. this is also confirmed by the holocene events recorded in many seismic profiles of the italian continental shelf where a major unconformity affects the top of the late pleistocene sequence (chiocci & normark, 1992; lecca et al., 1986; lecca et al., 1998). when sea level rises the rivers have almost no solid load and therefore all the energy is consumed in the erosion of bedrock. the result of such a transgression is a very thin layer of shells and coarse sediments associated with the ravinement surface that could be easily removed or weathered if it is not rapidly buried. this would be one of the reasons for the absence of marine deposits. in fact, the spedalino subsynthem, testifies to a phase of continental erosion after the planation and fills shallow valleys slightly incised into the bedrock. it also testifies to a relief located slightly to the west of the present-day basin. there is no other evidence of coarse clastic sediments coming from the west during the deposition of the meleto subsynthem, when a wide fine grained meander alluvial plain was established locally covered by a taxodium forest and affected by peat deposition. similar to what has been suggested in the nearby tiber basin and in other continental basins in the centralnorthern italy (coltorti & pieruccini, 1997a; 1997b) the peat-rich levels of the valdarno basin could be related to the early pliocene. the negative signal (albianelli et al, 1997) in the lower part of the sequence could correspond to the gilbert magnetic chron and therefore could be older than 4 ma (cande & kent, 1995). these layers are found lying unconformably on the bedrock along the margin of the chianti ridge. in the study area, a major unconformity developed after the deposition of the meleto subsynthem that was tilted up to 40° in proximity of the actual slope (fig. 9b, c and d). because the faults recognised along the western margin of the basin (figs. 2, 3) also dip 50-60° to the nne, and were sealed by the early pliocene sedimentation they underwent the same tilting. if we restore the geometry of the faults to before tilting they become sub-horizontal (x point in fig. 9). we do not know (this is the significance of the question marks in fig. 9c) if during this erosional phase the westward continuation of the oldest units, that is the connection with the siena basin, was interrupted or if this occurred in slightly later times. however, we can suppose that this plain was close to sea level since there are coheval marine sediments in the adjacent siena (to the west) and val di chiana basins (to the south). middle pliocene marine deposits are also found up to 800 m on the cetona mt. (passerini, 1964; liotta & salvatorini, 1994) that constitutes the southern continuation of the chianti ridge. in the southern part of the siena basin, between s. quirico d’orcia and montalcino a general unconformity was recognised but in the northern part, to the west of the study area, this evidence is lacking, most probably for the very few detailed sedimentological investigations (bossio et al., 1995; riforgiato et al., 2005). also in the siena basin, peat layers with trunks are found in the lower part of the sequence interlayered with marine coastal sediments (celle sul rigo fm.; liotta, 1996) recording the lco of g. puncticulata, around 3.6 ma that we suppose could also be a good chronological setting for the final deposition of the meleto clays. the following second cycle, that includes the uppermost coastal and deltaic sediments belongs to the zanclean/piacenzian interval, around 3.1. ma (riforgiato et al., 2005). the unconformity, that has also been recognised in many other tuscan basins would last about 500 ky. although the relationship between the different synthems testifies to a doming of the chianti mts., there is no evidence that it attained the present-day elevation. it could still represent a “drowned sill” between the siena and valdarno basins. similar evidence is widespread in the present-day adriatic basin testified to by seismic profiles to the west of the more external thrust fronts (ori et al., 1986; argnani & gamberi, 1995). in the adriatic sea, antiforms emerged for a short period from the sea level but were later planated and sealed by plio-pleistocene sediments generating progressive unconformities similar to what we observe in the chianti ridge. in the valdarno basin there is no evidence of sediments coming from the erosion of the present-day apennine ridge as also observed in the coheval sedimentation of the east tiber basin, located slightly to the south (c o l t o r t i & pieruccini, 1997a; 1997b). the apennine chain, at that time could represent simply another antiform in the peri-adriatic basin that only in later times was transformed into a mountain ridge. in this model, the valdarno basin represented the alluvial plain bordering the palaeo-po plain before the uplift of the apennines. the mountain chain was located further to the west. similar conclusions have recently been reached during the investigation of the barga basin (coltorti et al., sub78 m. coltorti, s. ravani & f. verrazzani mitted) and a large part of the apennine drainage system (coltorti, submitted). the montevarchi synthem, made by coarser sediments, testifies to the presence of a wide braided alluvial plain. the absence of lateral facies variations suggests that the connection with the siena basin, where there are a series of interlayered coastal and fluvial systems, could still be possible (fig. 9c). in fact, the source area for the montevarchi synthem was located to the west as also evidenced from paleocurrent measurements by g h i n a s s i & m a g i (2004). afterwards also the montevarchi synthem was tilted up to 20° eastwards indicating that the chianti ridge was still a growing antiform becoming a real “sill” separating the siena from the valdarno basins. there is a long sedimentary hiatus between the deposition of the montevarchi and bucine synthems and there are no elements to establish when the deformation ended. however, it is widely accepted that in the apennine area a generalised uplift activated at the end of the early pleistocene (ambrosetti et al., 1982; coltorti & pieruccini, 1997a; 1997b; calamita et al., 1999). the uplift is commonly responsible for the rapid incision of the river network (fig. 9e) interrupted by the deposition of the bucine synthem, during the late pleistocene in a landscape similar to the present-day one. 5. discussion and conclusions geological and geomorphological evidences together with facies analysis of the pliopleistocene sediments allow us to reconstruct the evolution of the chianti ridge and the westernmost part of the valdarno basin. the reconstruction also partially involves the nearby siena basin to the west and the apennine ridge to the east. we demonstrated that: a. the area was affected by an important planation surface 79 fig. 9 hypothesis of the dynamic evolution of the s. barbara basin. a: the beginning of the evolutive history, the spedalino and meleto subsynthems overlain by a major unconformity (u1) the deformed bedrock made by ligurian terrains, tuscan nappe and cervarola-falterona units; between the two subsynthems is inferred by a minor unconformity (early pliocene-late early pliocene, older than 3.5 ma); b: modelling of planation surface/unconformity (earlymiddle pliocene, 3.5÷3.1 ma); c: the montevarchi synthem lies unconformably (u2) on the previous sediments (3.1÷1.8? ma); d: the uplift of the chianti ridge has the effect of the formation of a new unconformity (u3) that cut the previous deposits (younger than 1.8 ma); e: the bucine synthem lies by unconformity (u3) on the previous sediments and it represents the last unit deposited during the late pleistocene. si: siena basin; ch: chianti ridge; va: valdarno basin; bu: bucine synthem; mo: montevarchi synthem; me: meleto subsynthem; sp: spedalino subsynthem; sb: sands; ag: clays; li: lignite banks; li: ligurian units; tu: tuscan nappe. 1: main unconformity; 2: minor unconformity. ipotesi dell’evoluzione dinamica del bacino della s. barbara. a: inizio della storia evolutiva, i subsintemi di spedalino e di meleto giacciono in discordanza (u1) sul substrato deformato fatto di unità liguri, falda toscana e unità cervarola-falterona; tra questi due subsintemi è ipotizzata una minore discordanza (pliocene inferiore-pliocene inferiore finale, più vecchio di 3.5 m; b: modellamento della superficie di spianamento/discordanza (pliocene inferiore – pliocene medio, 3.5÷3.1 ma); c: il sintema di montevarchi si depone in discordanza (u2) sui precedenti depositi (3.1÷1.8? ma); d: il sollevamento della dorsale del chianti causa la formazione di una nuova discordanza (u3) che taglia i depositi precedenti (più giovani di 1.8 ma); e: il sintema di bucine giace in discordanza sui precedenti sedimenti e rappresenta l’ultima unità depostasi durante il pleistocene superiore. si: bacino di siena; ch: dorsale del chianti; va: bacino del valdarno; bu: sintema di bucine; mo: sintema di montevarchi; me: subsintema di meleto; sp: subsintema di spedalino; sb: sabbie; ag: argille; li: banchi di lignite; li: unità liguri; tu: falda toscana. 1: discordanza principale; 2: discordanza minore. the growth of the chianti ... (early pliocene) (u1; fig. 9a). the deposition of the spedalino gravels (sp) is the result of the first subaereal erosion probably following deformational events. with the meleto subsynthem (me) the area became a wide flood plain whose limits are not well recognisable. all these events are older than 3.5 ma. b. a major antiform developed in correspondence with the chianti ridge after the deposition of the meleto subsynthem and before the deposition of the montevarchi synthem (fig. 9b). at the edge with the valdarno basin, which represented a large synform, a progressive unconformity (u2) separates the two sequences. a sedimentological signature of this tectonic event is missing except for the later occurrence of a generally coarser depositional environment. most probably the antiform was rapidly erased similar to what has been observed with seismic profiles in numerous sectors of the adriatic sea (ori et al.,1986; argnani & gamberi, 1995). these events occurred between 3.5. and 3.1.ma. c. deposition of the montevarchi synthem (mo; fig. 9c) the base of which possibly corresponds with the second cycle of the siena basin (sb) although the relationship between these two areas is unknown. the montevarchi synthem was deposited after 3.1 ma and slightly before the rena bianca sands, late pliocene in age. the relationship between the different sequences shows a progressive unconformity that reveals a differential movement between the ridge and the basin. d. a major unconformity (u3), in younger times, was modelled across the area finally separating the siena and valdarno basins. the re-exumation of the older rocks on top of the chianti ridge probably occurred during these events (fig. 9d). we suppose that it corresponds to the planation surface recognised by sestini (1981) at the summit of the chianti ridge, partly re-exuming the older one. e. the long erosive hiatus between the bucine and montevarchi synthems prevents us from establishing, if the ridge continued to rise during the early and middle pleistocene. however, most probably, differential movements ended during the early pleistocene and have been followed by a generalised uplift affecting both basins and ridges similar to what has been observed in the nearby areas (dramis, 1992; calamita et al., 1999). more recently, differential movements could also be connected with the activity of the normal faults delimiting the easternmost part of the valdarno basin (finetti et al., 2001). the valdarno, being filled with softer sediments and bordered by harder terrains, constituted a favourite site for a rapid erosion generating one of the most important fluvial systems of the apennines. the thickness of fluvial sediments of the montevarchi synthem that were removed is hard to evaluate. this long erosional phase cancelled the eventual connection with the surrounding lower valdarno and val di chiana basins. as evidenced above, the history of the chianti ridge is very complex with the main modelling pliocene phases occurring close to sea level. only since the earlymiddle pleistocene did the area gradually reach the present-day situation, mostly as a result of a combination of generalised uplift and differential erosion mostly activated by the deepening of the hydrographic network. the results of our investigations coupled with the recent thermochronological data led to an evolutionary scheme for the ridges and the basins of the northern apennines that is very different from that proposed in the past (elter et al.,1975; mazzanti & trevisan, 1978; alvarez, 1999). in that model the ridges rise progressively from w to e as the consequence of the eastward migration of the compressive front. however, our results shows that: 1. the chianti ridge, as the other ridges of the eastern sectors (calamita et al., 1999), are not anticlines but antiforms; 2, they were modelled after the emplacement of the ligurian units that moved along a major detachment; 3, there are no synsedimentary pliocene faults between the ridge and the basin but progressive unconformities as a result of deformations of the sedimentary cover; 4, there are no lacustrine deposits in these basins but they are mostly filled by meander and braided flood plain deposits, similar to what was recognised in the nearby east tiber valley (coltorti & pieruccini, 1997a; 1997b) and, in the barga basin to the north (landi et al., 2003; coltorti et al., submitted). there is also no evidence that suggests the existence of the main apennine divide with a ridge in a position similar to the present-day one up to the late pliocene and it is our conclusion that the upper valdarno could have represented the western part of the peri-adriatic basin. if this is confirmed, the eastward migration of the compressional movements and the creation of the present day apennine watershed was not gradual but very rapid in the geological time scale and occurred mostly during the pleistocene. references a.a.v.v. 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(1994) evoluzione sedimentaria e tettonica della parte centro-meridionale del bacino pliocenico di radicofani. studi geol. camerti, vol. spec., 1, 65-77. locardi e. (1982) individuazione di strutture sismogenetiche dall’esame della evoluzione vulcano-tettonica dell’appennino e del tirreno. mem. soc. geol. it., 24, 569-596. magi m. & sagri m. (1996) aeolian sand sheets and terminal fans: sedimetonlogical evidences of arid climate conditions in the plio-pleistocene valdarno basin (northern apennines, italy). 17th regional african european meeting of sedimentology, i.a.s. sfax, abstracts 172-173. malinverno a. and ryan w.b.f. (1986) extension in the tyrrhenian sea and shortening in the apennines as a result of arc migration driven by sinking of the lithosphere.tectonics, 5,2, 227-245. mariani i.p. & prato r. (1988) i bacini neogenici costieri del margine tirrenico: approccio sismico e stratigrafico. mem. soc. geol. it., 41, 519-531. martini i.p., & sagri m. 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(2005) chronostratigraphic revision of some pliocene basins in tuscany at the zanclean/ pliocene basins in tuscany at the zanclean/piacenzian boundary . bollettino della società geologica italiana, vol. spec. (3), 7 – 13. ricci lucchi f. (1986) the oligocene to recent foreland basins of the northern apennines. in: allen p.a., homewood p., (eds.), foreland basins. international association of sedimentologists, spec. publ., 8, 105-139. ruggieri g. (1970) note illustrative del foglio 108 (mercato saraceno). serv. geol. d'italia. sagri m. (1991) evoluzione stratigrafica e tettonica del bacino del valdarno superiore . memorie valdarnesi, serie 7, anno 157, 13-21. sagri m. & magi m. (1992) il bacino fluvio-lacustre del valdarno superiore (pliocene superiorepleistocene). in: guide all’escursione post-congresso, escursione b4, 76a riunione estiva: l’appennino settentrionale, società geologica italiana, firenze 24-26 settembre 1992. sestini a. (1936) stratigrafia dei terreni fluvio-lacustri del valdarno superiore. atti soc. tosc. sc. nat., 45, 37-41. sestini a. (1981) un’antica superficie d’erosione nei monti del chianti. riv. geogr. ital., 88, 214-220. t ongiorgi e. & t ongiorgi m. (1964) age of the miocene-pliocene limit in italy. nature, 201, 365367. trevisan l. (1952) sul complesso sedimentario del miocene superiore e del pliocene della val di cecina e sui movimenti tettonici tardivi in rapporto ai giacimenti di lignite e di salgemma. boll. soc. geol. it., 70, 65-78. v eneri f. (1986) la colata gravitativa della val marecchia. in: e. centamore & g. deiana (eds.) "la geologia delle marche". studi geol. cam., vol. spec., 83-87. 83 ms. ricevuto il 24 agosto 2006 testo definitivo ricevuto il 10 febbraio 2007 ms. received: august 24, 2006 final text received: february 10, 2007 the growth of the chianti ... sess 1_160211.pub il quaternario italian journal of quaternary sciences 24, (abstract aiqua, roma 02/2011), congresso aiqua il quaternario italiano: conoscenze e prospettive roma 24 e 25 febbraio 2011 the contribution of coseismic deformation to holocene relative sea level change: new data from the coastal areas of northeastern sicily and southern calabria carmelo monaco1, fabrizio antonioli2, luigi ferranti3, cecilia rita spampinato1 & giovanni scicchitano1 1 dipartimento di scienze geologiche, università di catania 2 enea casaccia, roma 3 dipartimento di scienze della terra, università federico ii, napoli corresponding author: c. monaco <cmonaco@unict.it> abstract: monaco c. et al., the contribution of coseismic deformation to holocene relative sea level change: new data from the coastal areas of north-eastern sicily and southern calabria. (it issn 0394-3356, 2011) a new geomorphologic survey has been carried out along coastal sectors of southern calabria (capo dell’armi) and north-eastern sicily (capo milazzo e capo schisò), here, the occurrence of raised holocene shorelines has been confirmed. in order to reconstruct the history of vertical deformation of the analyzed areas, the elevation of all the morphologic, biological and archaeological palaeo-sea level markers has been measured. these data, accompanied by absolute and archaeological dating, allowed us to assess a contribution of coseismic deformation, related to active faulting, to holocene relative sea level change. riassunto: monaco c. et al., il contributo della deformazione cosismica alle variazioni relative del mare durante l’olocene: nuovi dati dalle aree costiere della sicilia nord-orientale e della calabria meridionale. (it issn 0394-3356, 2011) una nuova campagna di rilevamento è stata eseguita lungo settori costieri della calabria meridionale (capo dell’armi) e della sicilia nord-orientale (capo milazzo e capo schisò), dove è stata confermata la presenza di linee di costa oloceniche sollevate. al fine di ricostruire la storia della deformazione verticale delle aree analizzate, sono state misurate le quote di tutti gli indicatori morfologici, biologici e archeologici del paleolivello del mare. i dati ottenuti, accompagnati da datazioni assolute e archeologiche, hanno consentito di accertare un contributo di deformazione cosismica,correlato ad attività di faglie, alla variazione relativa del mare durante l’olocene. key words: coseismic deformation, relative sea level, tectonic uplift,. southern italy parole chiave: deformazione cosismica, livello relativo del mare, sollevamento tettonico, italia meridionale 1 introduction sea level is the general reference for detecting ongoing vertical crustal movement and assessing shortand long-term tectonic instability in coastal areas (lajoie, 1986). vertical crustal movements can be deduced by archeological markers indicating apparent sea-level changes or by mapping and dating palaeoshorelines and separating the tectonic component from the eustatic and hydro-glacio-isostatic components of the relative sea level change (lambeck et al., 2011). data on relative sea level change occurred during the holocene along the coast of north-eastern sicily and south-eastern calabria (fig. 1) have been obtained using precise measures and radiometric dating of raised shorelines in the milazzo peninsula (see also rust & kershaw, 2000; scicchitano et al., 2011a), messina straits (see also ferranti et al., 2007; scicchitano et al., 2011b) and taormina area (see also stewart et al., 1997; antonioli et al., 2003; de guidi et al., 2003), the fastest uplifting sectors of the central mediterranean region. these strongly uplifted coastal regions are located along a main seismogenic system which affects the tyrrhenian side of southern calabria and the ionian coast of eastern sicily (see inset in fig. 1). 2. data analysis the detailed survey of capo milazzo (tyrrhenian coast of north-eastern sicily) confirmed the occurrence of raised late holocene shorelines and provided evidences of contribution of episodic motions to a steady regional tectonic uplifting. two palaeoshorelines have been measured at distinct elevations. the upper shoreline is represented by: i) a barnacle band at 2.0-3.0 m elevation; ii) a notch with a roof at ~2.10 m; iii) a marine deposit at 1.4-2.4 m elevation. the lower shoreline is characterized by a wave-cut platform extending from ~1 m down to the present coastline and by a barnacle band reaching a maximum elevation of 1.1 m. relationships between age and elevation suggest that the upper shoreline formed between 6200 and 1600 years ago and that a coseismic uplift (1.4-1.5 m) occurred between 1600 and 1400 years ago. similarly, a more recent coseismic uplift 41 43 42 (0.8-0.9 m) should be occured in the last 1400 years. an average uplift rate of 1.5 mm/yr has been estimated for the cumulative uplift. this could be related to the activity of a transpressive structure that is clearly evident in the offshore (e.g. the capo milazzo fold; fig. 1; argnani et al., 2007). in the taormina area (ionian coast of north-eastern sicily) a detailed survey of the capo schisò promontory has been carried out. here, a lava flow (6 ka old) is encrusted by calcarenitic marine deposits containing mollusk fossils and by algal a n d b a r n a c l e b a n d s , f o r m i n g t h r e e palaeoshorelines at elevation of 1.6-1.8, ~2.9 and 3.0-5.0 m a.s.l. new radiocarbon dating results, compared with published data (antonioli et al., 2003; branca, 2003, de guidi et al., 2003) suggest an average uplift rate of 1.7-1.8 mm/yr and the occurrence of three co-seismic uplift events in the last 5 ka (~4.0, ~2.0 and ≤1.0 ka ago). archaeological markers represented by ancient slipways in the naxos site of classic greek period (blackman & lentini, 2007), suggesting the occurrence of a 2.4 ka old palaeoshoreline at elevation of 2.4 m a.s.l., are consistent with morphologic and biological markers. taking into account the measured co-seismic displacements, seismic events should be related to the activity of an offshore tectonic structure (e.g. the taormina fault; fig. 1; de guidi et al, 2003). in the south-eastern sector of the messina straits (capo dell’armi, fig. 1), holocene uplift is suggested by coastal deposits and archeological remains tied to the coeval sea-level. along a 10 km coastal stretch, in the footwall of the armo fault (fig. 1), a continuous beachrock (see also pirazzoli et al., 1997) is raised up to 2 and locally to 3 m a.s.l., and was dated by radiocarbon analysis at ~5 ka bp. correction for the sea-level rise occurred since 5 ka yields uplift rates up to 1.2 mm/yr, a value comparable to the long-term footwall uplift rate, interpreted here as suggestive of ongoing late holocene fault activity. partly contrasting information for the historical time-span fig. 1 regional tectonic map of the southern part of the calabrian arc. double arrows show extension direction in western calabria and eastern sicily and contraction direction in the northern sicily offshore. af, armo fault; taf, taormina fault. the uplifted areas between capo milazzo and vulcano (from argnani et al., 2007) are indicated in grey (cmf, capo milazzo fold). carta tettonica regionale della porzione meridionale dell’arco calabro. le doppie frecce mostrano la direzione di estensione in calabria occidentale e sicilia orientale e la direzione di contrazione nell’offshore della sicilia settentrionale. af, faglia di armo, taf, faglia di taormina. le aree sollevate tra capo milazzo e vulcano (da argnani et al., 2007) sono indicate in grigio (cmf, piega di capo milazzo). c. monaco et al., 43 ms. received: testo ricevuto il come from archaeological sea level markers of inferred hellenistic age discovered in the area and studied by scicchitano et al. (2011b). in fact, a millstone quarry dips from the emerged beach down to 0.2 m below sea level. corrections for the functional height and for sea-level rise occurred since hellenistic times yields an uplift rate of 0.3 mm/yr. the different values of uplift rate obtained by geological and archaeological markers at capo dell’armi, located way far in the footwall of the armo fault, but in the immediate hanging-wall of a fault splay, could be explained by a cyclical alternation of co-seismic events on the two faults (aloisi et al., 2009). 3. discussion and conclusions the analysis indicate that vertical displacement occurred as an alternation of steady and episodic motions. precise compensation for eustatic changes and hydroglacio-isostatic adjustments (lambeck et al., 2010) constrains late holocene total uplift at ~ 1.2-2.0 mm/yr, almost equally balanced between the steady and the stick-slip components. late holocene steady uplift during the interseismic intervals at 1.0 mm/yr is consistent with long-term (0.1-1 ma) estimates (westaway, 1993). abrupt displacements are attributed to co and post-seismic footwall uplift along normal faults (taormina, capo dell’armi) or transpressive structures (milazzo), which occur onshore or are inferred to run immediately offshore the studied coastal outcrops. references aloisi m., ferranti l., mattia m. & monaco c. (2009) – a new analytical approach to the modeling of the 1908 earthquake source (messina straits) from the inversion of the 1897/1906-1909 levelling data: comparison with geological data. in riassunti estesi delle comunicazioni al 28° convegno nazionale gngts, trieste 16-19 novembre 2009, 75-78. antonioli f., kershaw s., rust d. & verrubbi v. (2003) – holocene sea-level change in sicily an its implications for tectonic models: new data from the taormina area, northeast sicily. marine geology, 196, 53-71. argnani a., serpelloni e. & bonazzi c. (2007) pattern of deformation around the central aeolian islands: evidence from multichannel seismics and gps data. terra nova, 19, 317–323. blackman d. j.& lentini m. c. (2007) graffiti from the dockyard of sicilian naxos. 13th international congress of greek and latin epigraphy, oxford. br a nca s. (2003) geological and geomorphological evolution of the etna volcano ne flank and relationships between lava flow invasions and erosional processes in the alcantara valley (italy). geomorphology, 53, 247261. de guidi g., catalano s., monaco c. & tortorici l. (2003) – morphological evidences of holocene coseismic deformation in the taormina area (ne sicily). journal of geodynamics, 36, 193-211. ferranti l., monaco c., antonioli f., maschio l., kershaw s. & verrubbi v. (2007) – the contribution of regional uplift and coseismic slip to the vertical crustal motion in the messina straits, southern italy: evidence from raised late holocene shorelines. journal of geophysical research, 112. lajoie k.r. (1986) coastal tectonics. in: geophysics studies committee, commission on physical sciences, mathematics and resources, active tectonics. national academy press, washington, 95-124. lambeck k., antonioli f., anzidei m., ferranti l., leoni g., scicchitano g. & silenzi s. (2011) sea level change along the italian coast during the holocene and projections for the future. quaternary int., in press. pirazzoli, p.a., g. mastronuzzi, j.f. saliege, and p. sanso` (1997), late holocene emergence in calabria, italy, marine geology, 141, 61–70. rust d. & kershaw s. (2000) holocene tectonic uplift patterns in northeastern sicily: evidence from marine notches in coastal outcrops. marine geology, 167, 105 – 126. scicchitano g., spampinato c. r., ferranti l., antonioli f., monaco c., capano m. & lubritto c. (2011a) – uplifted holocene shorelines at capo milazzo (ne sicily, italy): evidence of coseismic and steady-state deformation. quaternary int., in press. scicchitano g., lo presti v., spampinato c. r., gasparo morticelli m., antonioli f., auriemma r., ferranti l. & monaco c. (2011b) – millstones as indicators of relative seal level changes in northern sicily and southern calabria coastlines, italy. quaternary int., in press. stewart i., cundy a., kershaw s. & firth c. (1997) – holocene coastal uplift in the taormina area, north-eastern sicily: implications for the southern prolongation of the calabrian seismogenic belt. journal of geodynamics, 24, 37 -50. westaway, r., 1993. quaternary uplift of southern italy. journal of geophysical research, 98, 21741 -21772. the contribution of coseismic deformation to holocene ... january 10, 2011 10 gennaio 2011 imp.piccini& the italian register of natural hypogean geosites: a preliminary report leonardo piccini1,2, ugo sauro1,3, jo de waele1,4 & paolo mietto1,5 1società speleologica italiana, via zamboni 67 40123 bologna 2dipartimento di scienze della terra, università degli studi di firenze, via g. la pira, 4 – 50121, firenze; email: piccini@geo.unifi.it 3dipartimento di geografia, università degli studi di padova, ugo.sauro@unipd.it. 4dipartimento di scienze della terra, università degli studi di cagliari, geoam@unica.it. 5dipartimento di geologia, paleontologia e geofisica, università degli studi di padova, paolo.mietto@unipd.it. abstract: l. piccini et al., the italian register of natural hypogean geosites: a preliminary report. (it issn 0394-3356, 2005). since a couple of years, the italian speleological society (ssi) is carrying out a project for the realisation of a national inventory of hypogean natural geosites (geositi ipogei naturali = gin). a gin can be defined as "every subterranean natural void that represents exceptional naturalistic and/or cultural value, in the widest sense, in at least one of the following features: its intrinsic characteristics, its geological, geomorphologic or hydrogeological context, its morphodynamic significance, its content of hypogean landscape elements or significant materials or, finally, for the use man has made of it in time". the exceptionality mostly regards the scientific interest of the already performed or potential researches (global, european, national, regional or local relevance of the acquired or acquirable information), the historical and cultural interest and elements such as beauty, dimension, rarity, representativity and didactic or cultural interest. as a gin, entire cave complexes, single caves or single passages of caves can be chosen. five types of gin have been identified. gin for the intrinsic characteristics of the cave: concerns particularly well preserved parts of caves and their morphologies (erosion and corrosion forms), but also caves derived from particular speleogenetic processes (e.g. hyperkarst caves) or formed in special types of rock (e.g. gypsum caves). gin for the interest of the hosting karst area: in this type, caves with no special interest but representing important karst areas can be inserted. gin for the nature of the outcropping rocks: caves that allow a better understanding of petrography, mineralogy, tectonics, stratigraphy or palaeontology of the area. gin for the material contained in them: caves with scientifically important sediments, speleothems, evidences of palaeo-seismicity, palaeo-environmental indicators, archaeological or palaeontological deposits. gin for the importance in man's history: caves used by man in prehistory, but also the ones used more recently as places of cult, or caves important for the development of the speleological and karst explorations and studies. for all these types of gin, which can also coexist in the same site, the exceptional conditions of the phenomena have to be maintained, having different scales ranging from local up to global importance. a first list of italian gin has been compiled by a working group that has been instituted by the italian speleological society, composed of the regional responsibles of the cave registers and several experts. for every italian region no more than 1% of the total amount of natural caves has been identified as gin. in this paper a preliminary overview of some italian gin is given, reporting their names, distribution, type and importance. this provisional list already shows the exceptionality of the italian hypogean heritage on a european and global scale and these results encourage the working group to continue this research that aims for a better understanding and a growth of public awareness of this incredible speleological heritage. riassunto: l. piccini et al., il catasto italiano dei geositi ipogei naturai: risultati preliminari. (it issn 0394-3356, 2005). da alcuni anni la società speleologica italiana sta svolgendo un progetto, nato da un accordo con il servizio geologico nazionale (ora agenzia per la protezione dell’ambiente e per i servizi tecnici – apat), che ha come obiettivo il censimento dei geositi ipogei naturali (gin). sono da ritenere gin tutti quei vani sotterranei di origine naturale, le grotte per intenderci, che per le loro caratteristiche ambientali intrinseche, per i contesti geologici, geomorfologici e idrologici in cui si trovano, per il loro significato morfodinamico ed il loro contenuto d’elementi del paesaggio ipogeo, di materiali significativi o per l’uso che l’uomo ne ha fatto nel tempo, presentano caratteri di eccezionalità naturalistica e/o culturale in senso lato. l’eccezionalità riguarda soprattutto l’interesse scientifico delle ricerche già svolte o potenziali (rilevanza mondiale, europea, nazionale, regionale o locale dei dati acquisiti o acquisibili), l’interesse storico e culturale e i fattori di tipo estetico o dimensionale, di rarità, rappresentatività e interesse didattico-culturale. possono essere definiti gin interi complessi carsici, singole grotte oppure parti di esse. si distinguono cinque tipi di gin. gin per le caratteristiche intrinseche della grotta (ginci): comprende soprattutto cavità (o porzioni di esse) ben preservate con morfologie (forme d’erosione e/o di corrosione) e/o depositi di eccezionale importanza. in questa classe ricadono anche grotte dovute a processi genetici particolari (es. grotte ipercarsiche) oppure formate in rocce peculiari (es. grotte nei gessi). gin per l’interesse dell’area carsica in cui si trovano (ginac): comprende grotte rappresentative per aree carsiche di grande interesse. gin per la natura delle rocce affioranti (ginra): comprende quelle grotte che consentono di osservare le caratteristiche petrografiche, mineralogiche, tettoniche, stratigrafiche, paleontologiche delle rocce da esse attraversate, con un dettaglio e una ricchezza di informazioni non rilevabili all’esterno, in situazioni interessanti da un punto di vista strettamente geologico. gin per i materiali contenuti (ginmc): sono da considerare in questa categoria le cavità che contengono depositi fisici e/o chimici di particolare rilevanza scientifica. gin per l’uso da parte dell’uomo (ginan): rientrano in questa categoria le grotte che sono state utilizzate dall’uomo in tempi preistorici, storici o recenti a fini abitativi, di culto, di studio o altro. per ognuna di queste caratteristiche, che possono ovviamente anche coesistere, dovranno essere rispettate condizioni di eccezionalità dei fenomeni. tale eccezionalità può comunque spaziare da un contesto globale o continentale (gin di valore mondiale o europeo) a regionale o locale (gin di interesse nazionale, regionale e locale). e’ stata compilata una lista preliminare dei gin italiani da un gruppo di lavoro istituito dalla società speleologica italiana, composto dai responsabili regionali dei catasti delle grotte e da vari esperti. per ciascuna regione sono stati definiti come gin circa l’uno percento del totale numero di grotte censite a catasto. in questo lavoro è pubblicato un primo elenco di alcuni gin italiani, che mostra già da ora l’eccezionalità del patrimonio sotterraneo nazionale a livello europeo e mondiale, e questi risultati incoraggiano a proseguire questa ricerca, con l’obiettivo di aumentare le conoscenze e di sensibilizzare maggiormente l’opinione pubblica in modo da tutelare il nostro immenso patrimonio speleologico. keywords: caves, geosites, speleology, italy. parole chiave: grotte, geositi, speleologia, italia. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 155-162 156 l. piccini et al. 1. introduction the italian speleological society (ssi) and the national geological service (sgn, now agency for the safeguard of environment and technical services apat) have stipulated an agreement for the identification of the hypogean natural geosites (gin) of italy. actually, the exact meaning of the word “geosite” is not yet clear. for some researchers the main characteristic of a geosite is to be enjoyable for tourism and cultural purposes (geo-tourism); in this case a geosite can be regarded as an important element in the framework of economic development of local communities. for other researchers the scientific elements are the most important ones, and thus the geosite becomes an object that has to be studied and protected (brancucci & burlando, 2001; sauro & grandgirard, 1997). enjoying natural caves becomes a secondary fact because not all caves are of easy access, and the tourist adaptation of these difficult environments normally collides with their protection needs. in many cases the cave itself represents a geological site sensu latu, mostly combined with its naturalistic, environmental and/or cultural interest. in the speleological sense a gin could be defined as follows: "every subterranean natural void that represents exceptional naturalistic and/or cultural value, in the widest sense, in at least one of the following features: its intrinsic environmental characteristics, its geological, geomorphologic or hydrogeological context, its morphodynamic significance, its content of hypogean landscape elements or significant materials or, finally, for the use man has made of it in time". the exceptionality mostly regards the scientific interest of the already performed or potential researches (global, european, national, regional or local importance of the acquired or acquirable information), the historical and cultural interest and elements such as beauty, dimension, rarity, representativity and didactic or cultural interest. 2. definitions the following categories of geological and geomorphologic sites can be classified as gin: karst systems (or cave complexes); single caves; more or less important portions of caves. rarely entire karst systems can be considered as gin for the difficulty of their delimitation and their description. in the framework of this work five types of gin have been defined. 1) gin for the intrinsic characteristics of the cave in this category, those caves that contain relevant elements and forms that acquire exceptionality for their quantity, quality, exemplarity, dimension or aesthetic value are considered. these characteristics concern particularly well-preserved parts of caves and their morphologies (erosion and corrosion forms). as examples can be mentioned: caves with extremely well developed phreatic tubes, impressive underground canyon passages, immense underground rooms, extremely well developed erosion or corrosion forms on the ceilings and walls etc. in this category caves derived from particular speleogenetic processes (e.g. hyperkarst caves, thermal caves) or formed in special types of rock (e.g. gypsum caves, conglomerate caves, etc.) are also inserted. the morphologic and speleogenetic aspects acquire particular importance when these are in relation with the evolution of the environment in its multiple aspects (geology, geomorphology, climate, biology etc.). 2) gin for the interest of the hosting karst area in this type, caves with no special interest but representative for important karst areas can be inserted. this category comprises caves that, if evaluated singularly would not be considered gin because of the lack of special interest, but considered on a local scale they become important elements if evaluated in their geomorphologic and environmental context. 3) gin for the nature of the outcropping rocks it regroups caves that allow a better understanding of petrography, mineralogy, tectonics, stratigraphy or palaeontology of the area. in fact, in certain areas, caves can allow a much better and more detailed study of geological sequences, their structure and their mineralogical and/or palaeontological content. especially vertical caves sometimes cross through thick sedimentary sequences, and rocks are sometimes very well exposed. 4) gin for the material contained in them caves are geological traps in which sediments and biological remains are extremely well preserved, enabling the understanding of past morphological, climatic and biological conditions. among the scientifically important deposits the physical (alluvial deposits, detritus infillings, ancient loess-like sediments, palaeokarst deposits, etc.) and the chemical ones (speleothems, secondary minerals, etc.) can be mentioned, at the condition that they are of relevant importance for their characteristics (extension, dimension, representativity, aesthetic value, rareness, etc.) or for the indirect information that they can give on the evolution of the cave itself or of its environment (palaeo-climate, palaeo-geography, palaeo-seismicity, etc.). those caves that have enabled the reconstruction of past conditions thanks to their physical and/or chemical deposits are necessarily inserted in this category. also caves with important palaeontological, palaeo-ethnological or archaeological material refer to this class (fossil woods, guano deposits, prehistoric findings, important human fossils etc.) because these findings are also related to the favourable geomorphologic situation of the caves itself. finally, also those caves of particular biological interest can be inserted in this type of gin because both fossil fauna and flora (e.g. pollen) and cave dwelling fauna can represent testimonials of past biogeographical situations. 5) gin for the importance in man's history this category contains caves used by man in prehistory, but also the ones used more recently as places of cult (hermitage, palaeochristian rupestrian churches, etc.) or caves important for the development of the speleological and karst studies. for all these types of gin, that can also coexist, the uniqueness of the phenomena have to be maintained. this exceptionality can be defined in a global or continental (gin with a global or european value) up to a regional or local context (gin of national, regional or local interest). a single gin, in function also of its interest, can comprise an entire karst system (normally great cave systems with a complex evolution), entire caves for the presently known portions (in the case of caves with a peculiar genesis or the ones that allow a better understanding of geological sequences crossed by the cave itself, etc.) or only parts of caves (e.g. prehistoric and archaeological caves in which often only the entrance halls are of interest). 3. criteria for the definition of gin a first list of gin is now in progress, compiled simply relying on the personal knowledge of every single responsible of the regional cave registers, combined with the information given by local speleological experts. many situations are already well known and well documented even at a national level (piccini et al., 2001). a further selection can be derived from the interrogation of the cave register database (ferrari & piccini, 1996): the simple analysis for the longest and deepest caves, the altitude of the entrances (high mountain or submarine caves), the nature of the rocks (e.g. gypsum caves), the scientific interest (archaeology, biospeleology, mineralogy, etc.) or even the number of bibliographical references, can give rise to a reliable selection of possible gin. this list of “potential gin” needs of course further specific investigation to individuate the cases of real interest. for every region a first list of gin has thus been compiled, inserting the most important and interesting speleological sites, together with an essential reference list. following up every region will have to compile a list of potentially interesting sites that need a more appropriate and detailed study also in loco. for those sites that do not need any further examination a preliminary data base sheet, derived from the one used by the sgn (now apat), has been compiled. the characteristics of a gin are reported on a card which resemble that one proposed by the sgn and the centro documentazione geositi of the dipartimento polis università di genova. the recorded data concern localisation, fields of scientific interests, relevance valutation, description and bibliography. 4. some examples of gin in italy in this initial stage of cataloguing the working group instituted by the italian speleological society has already made a preliminary list of gin 157the italian register of ... distributed in several regions. for some of these sites a database sheet has already been compiled and the necessary fieldwork has confirmed its compatibility with the minimum criteria for its classification as a gin. hereunder some of these gin are briefly illustrated. 4.1 gin for the intrinsic characteristics of the cave monte corchia karst complex (caves register number of main entrances: 51, 52, 120, 741, t/lu; apuan alps, tuscany) the corchia cave is presently the longest cave in italy, being about 52 km long and 1195 m deep. the complex has 12 different entrances, from the top of the mountain, at 1637 m a.s.l., to the lower at 930 m a.s.l. (fig. 1). the morphologic setting of this exceptional karst system pertains to many interesting features of several points of view. anywhere, the most peculiar aspect probably concerns the relationship between morphological setting of cave passages and morphotectonic evolution (piccini, 1997). based on the vertical distribution of the phreatic and epiphreatic passages in the caves, four major generations of karst levels can be identified in the corchia complex. the first and most ancient generation lies above 1450 m a.s.l. and probably dates to late pliocene. the second level comprises more than 10 km of phreatic tubes located between 1000 and 1200 m a.s.l. the latter form a wide maze network that was subsequently affected by a major phase of vadose entrenchment. a recent dating (drysdale et al., 2001) suggests that also low levels passed from phreatic to vadose condition in the early pleistocene. the cave is also important for the in-filling deposits, with exotic pebbles related to an ancient hallogenic feeding (piccini, 1991). veja natural arch (caves register: 117, 465, 466, 467, 468 v/vr; monti lessini, venetia) the veja bridge, the most known natural arch in the monti lessini (venetian prealps), represents the remnant of the roof of a large cave chamber (fig. 2). this cavern collapsed mostly to form a karst window, a kind of collapse doline open downward, delimited by fig. 1 – the monte corchia karst complex. the sketch profile shows the vertical pattern of the cave emphasizing the morphological complexity and the policyclic evolution. 1) main cave entrances; 2) relict phreatic passages; 3) vadose passages. il complesso carsico del monte corchia. la sezione schematica mostra l’andamento verticale della grotta mostrandone la complessità morfologica e l’evoluzione policiclica. 1) ingressi principali; 2) condotti relitti d’origine freatica; 3) condotti d’origine vadosa. 158 rocky faces with several entrances of caverns (pasa, 1954; perna & sauro, 1976). this natural monument has been destination of field trips of the dwellers of the town of the po’ plain since middle ages. in 1496 the mantegna painted this bridge, as seen from the valley below and with the enrichment of some fantastic elements, in the camera degli sposi of the ducal palace of mantova. so this form represents one of the first natural monuments ever represented by an artist (mietto & sauro, 2000). from the point of view of its natural history the arch and the related caves are really interesting. the fillings of the karst cavities include very different materials as: a) very old soil sediments, probably of paleogene age, similar to those of the verona hills (latella & zorzin, 1989), b) basaltic lavas intruded inside karst galleries during late oligocene or early miocene (rossi & zorzin, 1993), c) pleistocene age fillings (pasa, 1950, bartolomei & broglio, 1975). the pleistocene age sediments are rich in palaeontological and archaeological remains that have been studied starting from the early xixth century. the presence of prehistoric man in the area is documented since lower palaeolithic. the geosite of veja bridge, which is now part of the natural regional park of the monti lessini, may be considered of global importance according to the coexistence of very different and relevant aspects. 4.2 gin for the interest of the hosting karst area spluga della preta cave (caves register: 1 v/vr; monti lessini, venetia) the spluga della preta in the monti lessini (venetian prealps) is one of the four earlyexplored deepest vertical cave systems in the world (fig. 3), with depths ranging, after the first campaigns, between 300 and 500 m. the early exploration of the preta took place in the years 1925, 1926 and 1927. due to the fact that the first explorers have overestimated the depth, this system was considered for nearly 30 years as the deepest cave in the world (stegagno, 1927; corrà, 1975; mietto & sauro, 2000). during more recent explorations the present bottom has been reached at the depth of 877 m (sauro et al., 1995). in the second half of the 20th century, its old fame attracted tens of expeditions from many different countries. for this reason the cave system was explored and studied and the great scientific importance of the cave itself and of the relative environment has been underl. piccini et al fig. 2 – the natural arc of ponte di veja, in the monti lessini karst area. l’arco naturale del ponte di veja, nell’area carsica dei monti lessini. fig. 3 a view from air of the summit plane of corno d’aquilio. the arrow indicates the entrance-doline of the spluga della preta cave (photo oca). veduta aerea del pianoro sommitale del corno d’aquilio. la freccia indica la dolina d’ingresso della spluga della preta (foto oca). 159 stood (maucci, 1954; sauro, 1974). the preta system is the result of a speleogenetic evolution occurred in a peculiar geological and geomorphologic environment. speleogenesis has been controlled by: a) the lithological sequence, characterised by a hanging aquifer hosted inside the dense network of fractures of a marly limestone (biancone), similar to the chalk, loosing water in the underlying pure limestone, b) the tectonic setting of the area (the cave system is inside a tectonic wedge evolving as a thrust structure), c) the deepening of the large lateral valley of the adige river, very near to the cave. the cave is also of great biological interest. it hosts endemic species of invertebrates discovered in this cave, and among these the largest cave carabid ever found in the world can be mentioned. the geosite of spluga della preta, which is now part of the natural regional park of the monti lessini, may be considered of global importance according to the coexistence of very different and relevant aspects. 4.3 gin for the nature of the outcropping rocks olivifer cave (caves register: 1000 t/lu; apuan alps, tuscany) this typical alpine-like karst system has a depth of 1215 and is one of the deepest caves in italy (fig. 4). the cave has two entrances and develops mainly in metadolomite of triassic age (carnian-norian) (piccini, 1992). the first part of the cave, until the depth of 900 m, follows the overturned stratigraphic contact between dolomitic marble (a heteropic facies of carrara marble) and dolomite. the cave allows an exceptional vision of this geologic passage that is fundamental in the comprehension of the evolution of the tuscan carbonate shelf at the passage between triassic and jurassic. being an active cave, the vertical passages show the petrographic and sedimentological features of the rocks with great detail and, despite the local intensive tectonic deformation, allow to reconstruct the phases of emersion that affected this part of the carbonate shelf. 4.4 gin for the material contained in them santa barbara cave (caves register: 210 sa/ca; iglesiente, sardinia) this cave, open to public since a couple of years, has been discovered in the early fifties during the excavations inside the san giovanni mine at iglesias and has no natural entrance (fig. 5). the importance of this small cave, that has a total development of only about 110 meters (fabbri & forti, 1981), is to be found in its geologic characteristics (forti & perna, 1981); it is probably one of the oldest caves in italy. the natural void has been formed in the limestone of lower cambrian age and could be related to a triassic karst cycle. the big room is well decorated by great columns, attractive stalactites and stalagmites, while the roof and the walls are completely covered with barite crystals, certainly a rare mineral in the cave environment, testifying its complex genetic history (rossetti & zucchini, 1957; forti & perna, 1982). onice cave (caves register: 234 t/lu; apuan alps, tuscany) the onice cave is a typical example of cave affected by a long and almost continuous phase of chemical and physical in-filling, following the first phreatic enlarging phase. it consists of a 150 m long segment of a large phreatic the italian register of ... fig. 4 sketch geologic profile of olivifer cave: note the structure-controlled vertical pattern of the cave. 1) dolomitic marble, 2) phyllite lens, 3) shaly marble, 4) dolomite, 5) palaeozoic basement. (from: piccini, 1992). profilo schematico dell’abisso olivifer: si noti il controllo esercitato dalla struttura sull’andamento verticale della grotta. 1) marmi dolomitici; 2) lenti di filladi; 3) marmi scistosi; 4) dolomie; 5) basamento paleozoico. (da: piccini, 1992). 160 tube, which opens at 573 m a.s.l. along a secondary crest of the frigido basin, near to massa. this cave hosts a flowstone, at least 5 m thick that was quarried in the past for getting ornamental stone. the top bed of the flowstone has an age exceeding the limits of alpha u-th dating (>350 ka), thus, according to these data, we can assert that onice was active as a phreatic conduit in the middle pleistocene, probably before 500 ka bp (piccini et al., 2003). the flowstone is covered by an 8 m thick sediment made up of dolomitic fine sand, probably related to upper pleistocene cold periods characterized by mechanical denudation and removal of soils. the sediment, which shows a varve-like banding, is interlayered with datable calcite crusts. the flowstone, presently under investigation, offers the possibility to get a complete and medium-definition record of environmental changes during middle and late pleistocene. lamalunga cave (caves register: 1295 pu/ba; altamura, apulia) the cave, in the area of the murge of altamura, is made up of a tunnel, which extends not far beneath the surface. the morphologic setting suggests a long evolution from phreatic condition to a phase in which the cave turns into a vadose zone and then progressively undergoes a decrease in the water flow. the cave was then affected by collapsing and concretioning cycles over an unknown time period. it is during this last evolution phase that the palaeontological deposition occurs. the cave of lamalunga rose to the world attention in 1993 thanks to the discovery of a complete skeleton of an archaic man (forti, 1993). the skeleton of the now named man of altamura, is located in a lateral branch of the main gallery. the bones are almost completely covered by calcite, a stalagmitic formation covers part of the maxillary, leaving the supraorbital arch visible (fig. 6). the cranium morphology resembles that of the neanderthal type, and the characteristics of the skeleton indicate that the individual was an adult male. thanks to the completeness and exceptional state of preservation and to the presence of numerous elements of the almost complete post-cranial skeleton, the man of altamura represents one of the most surprising palaeontological discoveries ever made in italy and in europe. 4.5 gin for the importance in man's history la verna caves (caves register: 51and 600 t/ar; arezzo, tuscany) the la verna sanctuary is one of the most famous cult sites of catholic church in italy (vianelli, 1994). the sanctuary stays on a hanging cliff made up of calcareous sandstone lying on shale, of tertiary age. the l. piccini et al. fig. 5 – vertical and plan view of the santa barbara cave, (from: fabbri & forti, 1981). vista verticale ed in pianta della grotta di santa barbara, (da: fabbri & forti, 1981). fig. 6 the skeleton of the man of altamura, partially cemented by speleothems, (reprinted from: forti, 1993). lo scheletro dell’uomo di altamura, parzialmente inglobato da speleotemi, (ristampato da: forti, 1993). relief is affected by de-stressing fractures due to gravitative deformation, which led to the formation of trenches on the top surface and fissures at the base. the site is located along one of the main old ways crossing the northern apennines and thus it is since a long time a site of refuge for man. in may 1213, san francesco made the mountain a site for hermitage and pray. during the work for building the small church of santa maria degli angeli, san francesco and his friars found a refuge in small caves and niches, formed by rock collapses. the morphological relevance of these caves is minimal, but the geological setting, the particular genetic process of the caves and, moreover, the historical events, made this site one of the most important geomorphosites of the northern apennines. san giovanni cave (caves register: 81 sa/ca; iglesiente, sardinia) san giovanni cave is located near the little town of domusnovas in cagliari province, and is characterised by a natural tunnel that crosses monte acqua from north to south for a total length of more than 800 meters (fig. 7). this tunnel has been excavated by the sa duchessa river in the waxy limestone of the so-called "metallifero" (gonnesa group, lower cambrian) (de waele & pisano, 1998). the cave has a partially explored submerged branch from which rises a river with an average discharge of 100 l/s. in roman times this water was conveyed into an aqueduct that supplied cagliari until some decennia ago. known since prehistory, only in the last decades this cave was the subject of intense speleological exploration, bringing its development to about 5 km with the discovery of at least two fossil cave levels testifying a complex speleogenesis (bianco et al., 1992; papinuto & naseddu, 1996; naseddu, 1998). from an archaeological point of view, aside the already mentioned roman aqueduct, a big megalithic wall (ca. 1500 b.c.) is still clearly visible at the southern entrance (alba, 1982). the cave has a historical interest for the presence of a road that crosses the whole natural tunnel. since half the 19th century, in fact, this natural passage enabled horse-carts first, trucks later, to carry the pb and zn mineral mined in the sa duchessa valley and in the mountains to the cixerri valley where a railway brought the ore to the industrial plants or harbours. the cave has also great biospeleological interest, with the presence of an important bat colony and many species of arthropods, several of which are endemic and sometimes of great biogeographical importance (grafitti, 2002) 5. conclusions presently, about 50 gin have been preliminary selected by the working group in the whole italian territory, but we presume that the number of gin will be probably more than 300. for all these sites a sheet will be compiled that will enable the construction of a database. the preliminary data already show the great importance of the speleological heritage in italy, probably representing one of the most important of the european continent. many work is still to be done, such as the raise in public awareness of our important speleological geosites, their sustainable management and their protection where needed, in order to deliver our subterranean heritage to the future generations. 161the italian register of ... fig. 7 the lower entrance of san giovanni cave, close to domusnovas. l’entrata inferiore della grotta di san giovanni, presso domusnovas. acknowledgments a special thank to franco cucchi and paolo forti for their reviews. research supported by società speleologica italiana. references alba l. (1982) i depositi archeologici nelle grotte dell'iglesiente memorie istituto italiano di speleologia 1(1), pp. 35-42. bartolomei g. & broglio a. (1975) risultati preliminari delle nuove ricerche nei depositi quaternari della grotta a di veja boll. museo civ. st. nat. verona, 11, pp. 217-238. bianco l., chessa l., de waele j., naseddu a. & sanna f. (1992) le tentazioni di san giovanni speleologia, 26, pp. 16-21. brancucci g. & burlando m. (2001) la salvaguardia del patrimonio geologico franco angeli ed., 96 pp. corrà g. (1975) la spluga della preta, cinquant'anni di esplorazioni natura alpina, 3, pp. 1-239. de waele j. & pisano m. (1998) interazione fra attività mineraria ed un acquifero carsico: l'esempio di barraxiutta (domusnovas, sardegna sud-occidentale) in: crema & ferrarese (eds.), atti del convegno nazionale sull'inquinamento delle grotte e degli acquiferi carsici e possibili ricadute sulla collettività, ponte di brenta, 26-27 settembre 1998, pp. 195-209. drysdale r., bruschi g., fallick a.e-. heijnis h., isola i., roncioni a. & zanchetta g. (2001) primi dati cronologici ed isotopici di una stalagmite dell’antro del corchia sviluppata durante lo stage isotopico 7 (alpi apuane, italia) atti vii congr. fed. spel. tosc., pp. 99-101. fabbri m. & forti p. (1981) esplorazioni nell'iglesiente sottoterra, 59, pp. 31-35. ferrari g. & piccini l. (1996) the register of the italian caves atti ii° symposium progeo, roma 20-22 maggio 1996, mem descr. carta geol.d’ it., liv (1999), pp. 279-284. forti p. & perna g. (1981) la turisticizzazione della grotta di santa barbara nella miniera di san giovanni e la creazione di un museo minerario ad essa connesso (iglesias sardegna sud occidentale) le grotte d'italia, 4(10), pp. 181-187. forti p. (1993) il babbo del neanderthal abitava in puglia? speleologia, 29, pp. 6-7. forti p. & perna g. (1982) concrezioni e cristallizzazioni nei karst dell'iglesiente (sardegna sw) sottoterra, 63, pp. 39-48. grafitti g. (2002) la biospeleologia in sardegna. storia e prospettive in: j. de waele (ed.), atti del convegno di studio il carsismo e la ricerca speleologica in sardegna, cagliari 23-25 novembre 2001, anthèo, 6, pp. 269-298. latella l. & zorzin r. (1989) studi speleologici su una miniera di “terra gialla” di verona la lessinia ieri oggi domani: quaderno culturale 1999, pp. 47-52. maucci w. (1954) analisi morfogenetica della spluga della preta atti vi congresso naz. speleologia, trieste, 40 pp. mietto p. & sauro u. 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(1957) baritina della grotta di santa barbara rendiconti seminario facoltà scienze università di cagliari, 26(3-4), pp. 240255. rossi g. & zorzin r. (1993) nuove osservazioni sul complesso carsico del ponte di veja (m.ti lessini vr) atti xvi congr. naz: speleol., udine 1990, le grotte d’italia, s.iv, xv, pp. 41-49. sauro u. (1974) aspetti dell'evoluzione carsica legata a particolari condizioni litologiche e tettoniche negli alti lessini boll. soc. geol. it., 93, pp. 945-969. sauro u. & grandgirad v. (1997) geotopes and their management: results of the discussion on "geotopes" proceedings 12th intern. congr. speleol., 1997, switzeland, v. 6, pp. 109-110. sauro u., menichetti m. & troncon g. (1995) "operazione corno d'aquilio": an example of cleaning operation, exploration and scientific analysis of a karst system acta carsologica, 24, pp. 487-499. stegagno g. (1927) l'abisso più profondo del mondo sinora esplorato l'esplorazione della spluga della preta. grotte d'italia, 1-2, pp. 21-34. vianelli m. (1994) la verna. il monte di san francesco ed. mv, bologna, 64 pp. 162 l. piccini et al imp.spalluto_moretti evidenze di neotettonica (pliocene medio pleistocene superiore) nel settore occidentale del promontorio del gargano (italia meridionale) luigi spalluto 1 & massimo moretti 1-2 1 dipartimento di geologia e geofisica. 2 centro interdipartimentale di ricerca per la valutazione e mitigazione del rischio sismico e vulcanico. università degli studi di bari, via e. orabona 4, 70125 bari (italy) l.spalluto@geo.uniba.it m.moretti@geo.uniba.it riassunto: l. spalluto & m. moretti: evidenze di neotettonica (pliocene medio pleistocene superiore) nel settore occidentale del promontorio del gargano (italia meridionale). (it issn 0394-3356, 2005). il settore di studio è localizzato lungo il bordo occidentale del promontorio del gargano, in un’area compresa fra san severo e apricena (foggia). esso comprende quindi parte del dominio geodinamico-strutturale dell’avampaese apulo e parte del dominio dell’avanfossa bradanica. in particolare, il primo comprende un tratto del margine occidentale del promontorio del gargano costituito in prevalenza da rocce carbonatiche autoctone mesozoiche e cenozoiche interessate da strutture tettoniche legate a deformazione di natura fragile prodottesi in prevalenza durante le fasi orogenetiche appenniniche; il secondo corrisponde ad un tratto dell’adiacente depressione tettonica del tavoliere delle puglie coperta da depositi silicoclastici marini e continentali e costituente parte del settore nord-orientale dell’avanfossa bradanica. l’area in esame è considerata, sulla base dei dati di letteratura, un’importante zona sismica: la maggior parte delle faglie è stata attiva probabilmente già dalla fine del cretaceo. sulla base di dati strutturali e stratigrafici alcuni autori riconoscono infatti due fasi tettoniche distinte nel cretaceo e nel miocene, menzionando la tettonica plio-pleistocenica come un’unica fase geodinamica successiva. nell’intero avampaese apulo però, il plio-pleistocene è caratterizzato da due distinte fasi di evoluzione geodinamica: una marcata subsidenza (circa 2 mm/anno nel pliocene pleistocene inferiore) connessa alla subduzione appenninica ed una successiva fase di moderato uplift (circa 0,5 mm/anno nel pleistocene medio-superiore). il sollevamento dell'avampaese apulo è tuttora attivo e gran parte delle strutture tettoniche ad attività recente si inserisce in questo quadro geodinamico. l’obiettivo di questo lavoro è quello di evidenziare i dati stratigrafici utili a differenziare le strutture ad attività pliocene pleistocene inferiore da quelle con attività più recente. gran parte dei dati stratigrafici e tettonici è stata raccolta nell'ambito dei nuovi fogli della carta geologica d'italia (scala 1:50.000) durante il rilevamento geologico del foglio n° 396 "san severo". la fase di subsidenza (pliocene – pleistocene inferiore) connessa alla subduzione appenninica è registrata nell’area di studio dalla tettonica distensiva che interessa la calcarenite di gravina (localmente attribuita al pliocene medio-superiore). le evidenze di tettonica sinsedimentaria sono rappresentate essenzialmente da faglie di crescita e dicchi nettuniani. la fase di sollevamento pleistocenica è segnata dalla presenza di depositi marini e continentali terrazzati del supersintema del tavoliere delle puglie che marcano la graduale riemersione di questo settore dalla fine del pleistocene inferiore fino all'attuale. il progressivo sollevamento dell'area in esame può essere desunto dallo studio dei caratteri evolutivi delle unità marine e continentali terrazzate. le unità terrazzate più antiche sono interessate da faglie prevalentemente distensive e datano quindi l’attività di queste strutture al post-pleistocene medio. abstract: l. spalluto & m. moretti: neotectonics of the western sector of the gargano promontory (plio-pleistocene, southern italy). (it issn 0394-3356, 2005). the analysed area is located in the western part of the gargano promontory (northern emerged sector of the apulian foreland, southern italy): this area comprises the mesozoic and cenozoic carbonate units of the apulian foreland and the northern sector of the plio-pleistocene bradanic trough. many authors mention the western portion of the gargano area as an important seismogenic zone, which have suffered some mediumto high-magnitude historical and instrumentally-recorded earthquakes. in this area, some of the faults with a suggested recent to present-day activity have probably been active since mesozoic time and it is often very hard to establish the age of the observed displacements. on the basis of the available stratigraphic and structural data, some authors have distinguished at least two different tectonic phases in late cretaceous and miocene times. moreover, they mentioned a plio-pleistocene tectonic activity as a successive single tectonic phase. according to the regional data, during the plio-pleistocene, this area (and the entire apulian foreland) was subject to two different tectonic phases: the first one (pliocene to lower pleistocene in age) was related with the active subduction of the apulian foreland beneath the southern apenninic chain; during this phase, the apulian foreland recorded an high subsidence rate (about 2 mm/yr); from the sicilian to present-day, the entire apulian foreland was subject to a moderate uplift (less than 0,5 mm/yr). it is very important to distinguish the structural elements of the subsidence stage from them associated with the uplift since only the last ones are directly related with the present-day active tectonics. during the geologic survey for the carg project (san severo 1:50.000 sheet) we have found much evidence of neotectonics in this area and the aim of this work is to show the stratigraphically–recorded tectonic activity during the plio-pleistocene. in the apricena area (masseria zingari locality), some extensional features have been observed: they are represented by narrow grabens (few tens of meters in length) which cut miocene limestones and are transferred to the overlying calcarenite di gravina formation (late pliocene in age). the synsedimentary activity of these grabens is documented by the presence of narrow folds and by the variations in thickness of the calcarenite di gravina formation. the maximum displacement is always less than 5 m and it decreases upwards. along the cuts of the older and inactive railway in the same area, a complex distensive fault occurs in the calcarenite di gravina formation (and in its miocene substrate): folds and growth structures involve the overlying calcarenites along the primary and secondary fault planes. the last evidence of the subsidence phase is given by large-scale neptunian dykes (up to 5 m in height): they are restricted at the contact between miocene limestones and the overlying calcarenite di gravina formation and are represented by large conical fractures in the miocene substratum which are filled by the overlying pliocene calcarenites; that is a record of synsedimentary extensional tectonic activity since the overlying unit suffers soft-sediment deformation and many decimetric beds are downward-projected and/or irregularly folded during the extensional brittle deformation of the substratum. the middleto upper-pleistocene uplift of this area is chiefly documented by the presence of marine and continental terraced deposits il quaternario italian journal of quaternary sciences 19(1), 2006 143-154 144 l. spalluto & m. moretti 1. introduzione l’area di interesse ricade nel foglio n° 396 “san severo” (scala 1:50.000) e comprende ad est il settore nord-occidentale del gargano e ad ovest un ampio settore del tavoliere delle puglie (fig. 1). quest’area rappresenta un’importante zona sismogenetica in cui sono stati registrati strumentalmente e su base storica terremoti di magnitudo moderato-alta (tinti et al., 1995; piccardi, 1998; borre et al., 2003; patacca & scandone, 2004; piccardi, 2005). in questo lavoro vengono analizzati i dati stratigrafici inediti emersi nel corso del rilevamento geologico per la realizzazione del foglio 396 “san severo” alla scala 1:50.000 e relativi alle unità plio-pleistoceniche affioranti nell’area, che rappresentano: records stratigrafici delle differenti fasi geodinamiche cui è stata soggetta l’area d’interesse; vincoli stratigrafici per datare direttamente le faglie certamente attive durante il plio-pleistocene. è opportuno evidenziare che nella recente letteratura in questo stesso settore di indagine sono stati riconosciuti gli effetti di una sola fase tettonica attiva durante il plio-pleistocene, che avrebbe principalmente riattivato strutture formatesi durante le fasi tettoniche precedenti (chilovi et al., 2000). queste evidenze non collimano con i dati regionali noti per l’avampaese apulo e la fossa bradanica, che, in questo stesso intervallo di tempo, indicano la presenza sia di effetti connessi alla fase tettonica distensiva che si estende dal pliocene fino al pleistocene inferiore interessando l'intero avampaese apulo coinvolto nella subduzione verso ovest al di sotto dell'appennino meridionale, sia di una successiva fase di sollevamento attiva a partire dal pleistocene medio (ci a r a n f i et al., 1979; 1983; 1988; p i e r i , 1980; ricchetti et al., 1988). scopo di questo lavoro è quello di evidenziare, attraverso i nuovi vincoli stratigrafici, le strutture tettoniche ad attività pliocene medio pleistocene inferiore da quelle con attività più recente connesse alla fase di uplift del pleistocene mediosuperiore; queste ultime sono le uniche che hanno anche un'importanza ai fini degli studi di tettonica attiva. effetti di tettonica sinsedimentaria connessi alla fase di subsidenza, molto simili a quelli descritti in questo lavoro lungo il settore occidentale del promontorio del gargano, sono stati segnalati anche lungo il bordo bradanico delle murge, nelle profonde incisioni del f. bradano e dei suoi affluenti (tropeano et al., 1994). i dati stratigrafici e tettonici sono stati raccolti nell'ambito della realizzazione dei nuovi fogli della carta geologica d'italia (scala 1:50.000 – progetto c.a.r.g.) durante il rilevamento geologico del foglio n° 396 "san severo" di cui g. ricchetti è stato responsabile scientifico e p. pieri direttore dei rilevamenti. 2. inquadramento geologico l’area di studio (fig. 1) ricade nel settore occidentale del promontorio del gargano nel settore di transizione tra i domini di avampaese (“avampaese apulo” in d’argenio et al., 1973; ricchetti, 1980) e di avanfossa (“fossa bradanica” in selli, 1962; d’argenio et al., 1973) dell’appennino meridionale. la porzione di avampaese affiorante è costituita da calcari meso-cenozoici di piattaforma carbonatica (“piattaforma apula” in d’argenio, 1974) interessati prevalentemente da una deformazione tettonica disgiuntiva (funiciello et al., 1988; be r t o t t i et al., 1999; ch i l o v i et al., 2000). secondo studi strutturali e stratigrafici recenti, nell’area di studio sono state differenziate una fase tettonica supracretacica (chilovi et al., 2000; morsilli et al., 2002; spalluto, 2004), una fase tettonica del miocenepliocene inferiore coeva con le fasi più importanti dell’orogenesi appenninica (chilovi et al., 2000) ed una tettonica plio-pleistocenica. quest’ultima viene spesso that crop out from 140 m a.s.l. to 20 m a. s. l. the documentation of the discrete faults associated with this uplift phase is often very difficult because there are not extensive and continuous outcrops of the middle-upper pleistocene units. nevertheless, in a quarry located to the nw of apricena town we have found an extensional fault that cuts the entire thickness of a marine terraced unit (colle degli ulivi subsynthem). the fault is subvertical, e-w oriented and the maximum vertical displacement is up to 20 m in height. similar tectonic features have been reported in the younger san severo subsynthem. parole chiave: neotettonica, calcarenite di gravina, argille subappennine, supersintema del tavoliere delle puglie, pliocene mediopleistocene superiore, promontorio del gargano, italia meridionale. keywords: neotectonics, calcarenite di gravina, argille subappennine, tavoliere delle puglie supersynthem, middle pliocene-upper pleistocene, gargano promontory, southern italy. fig. 1 schema geologico del settore settentrionale della regione puglia ed ubicazione del foglio 396 "san severo". geologic sketch of the northern sector of the apulia region. the location of the sheet 396 "san severo"is shown. identificata come una singola fase che avrebbe riattivato strutture più antiche (chilovi et al., 2000; tondi et al., 2005). nell’avampaese apulo e nella fossa bradanica, il plio-pleistocene è segnato da due distinte fasi geodinamiche (ricchetti et al., 1988; doglioni et al., 1994; 1996). in particolare, durante il pliocene mediopleistocene inferiore, i settori più occidentali dell’avampaese apulo sono stati interessati da una marcata fase di subsidenza (circa 2 mm/anno in doglioni et al., 1994) connessa alla subduzione appenninica. durante questa fase, ampi settori di avampaese evolvono ad avanfossa. in tale contesto la sedimentazione nella fossa bradanica è avvenuta dapprima con depositi carbonatici di mare basso ascritti alla calcarenite di gravina e successivamente con le emipelagiti siltoso-argillose delle argille subappennine. la calcarenite di gravina (pliocene medio-pleistocene inferiore) poggia in discordanza con un contatto trasgressivo sui calcari ai bordi degli alti strutturali relativi dell’avampaese apulo (tropeano & sabato, 2000; pomar & tropeano, 2001). le argille subappennine (pliocene medio-pleistocene inferiore) poggiano in continuità di sedimentazione sulla calcarenite di gravina e marcano la fase di massimo approfondimento della fossa bradanica (pieri et al., 1996). questa unità rappresenta il substrato sedimentario su cui poggiano tutte le unità marine e continentali più recenti. i dati di letteratura indicano che, a partire dal pleistocene medio, l'intero avampaese apulo è stato invece soggetto ad un moderato sollevamento (ciaranfi et al., 1983; ricchetti et al., 1988; doglioni et al., 1994; 1996; gambini & tozzi, 1996), testimoniato a livello regionale dai depositi regressivi della fossa bradanica e dai depositi marini terrazzati che si rinvengono a quote decrescenti, dai più antichi ai più recenti (ciaranfi et al., 1988; tropeano et al., 2002). nell’area di interesse tali depositi vengono riportati nella cartografia geologica ufficiale alla scala 1:100.000 (f°155 “s. severo” boni et al., 1969; f°156 “s.marco in lamis” cremonini et al., 1971; f°163 “lucera” jacobacci et al., 1967; f° 164 “foggia” merla et al., 1969) con denominazioni differenti; in alcuni casi vengono descritti in continuità sulle argille subappennine (boni et al., 1969; cremonini et al., 1971), in altri casi come depositi marini terrazzati post-calabriani (jacobacci et al., 1967; merla et al., 1969). nella carta geologica dell’appennino meridionale (bonardi et al., 1988) nel tavoliere delle puglie, viene distinta una zona, al di sopra dei 350 m di quota, nella quale sarebbero presenti depositi correlabili con la successione bradanica (riconosciuti a sud dell’ofanto da ricchetti, 1967 e valduga, 1973) ed un settore meno elevato che si estende fino al golfo di manfredonia nel quale sarebbero presenti depositi marini terrazzati. nei lavori successivi sul plio-quaternario del tavoliere delle puglie (boenzi et al., 1992; caldara & pennetta, 1989; 1993; capuano et al., 1996; aucelli et al., 1997) sia le denominazioni di tali depositi che le attribuzioni cronologiche si riferiscono ora allo schema proposto da bonardi et al. (1988), ora a quello della cartografia ufficiale 1:100.000 (boni et al., 1969). più recentemente, gallicchio et al. (2002) analizzando il settore pedemontano del tavoliere (dall’appennino fino all’area di lucera, appena a sud dell’area qui analizzata) riconoscono unicamente depositi terrazzati continentali (pleistocene medio-superiore) in erosione direttamente sulle argille subappennine. 145evidenze di neotettonica ... i rilevamenti condotti per la realizzazione del foglio n° 396 "san severo" (scala 1:50.000) hanno consentito sia di meglio definire le aree di affioramento delle unità basali della fossa bradanica (calcarenite di gravina ed argille subappennine), sia di proporre un nuovo schema stratigrafico per i depositi del pleistocene medio-superiore. 3. la fase di subsidenza del pliocene medio – pleistocene inferiore 3.1 dati stratigrafici la calcarenite di gravina (pliocene medio-superiore) la calcarenite di gravina rappresenta l’unità basale della successione plio-pleistocenica della fossa bradanica (ciaranfi et al., 1988). è conservata in lembi nel settore nord-occidentale dell’area di studio, ad est dell’abitato di apricena e nel settore nord-orientale del foglio san severo in località monte granata (fig. 2). il limite inferiore della calcarenite di gravina è inconfome; a seconda della locale strutturazione del substrato, tale formazione poggia in discordanza o in paraconcordanza sia sui calcari mesozoici (giurassico superiorecretaceo superiore) che sui calcari del miocene (serravalliano-tortoniano). la base della calcarenite di gravina corrisponde ad una netta superficie di ravinement su cui poggia un deposito conglomeratico grossolano spesso circa 40-50 cm, costituito da clasti carbonatici derivanti dal substrato locale, profondamente bioerosi e di dimensioni variabili da pochi centimetri a qualche decimetro immersi in una matrice biocalcarenitica con tessitura packstone/grainstone in cui si riconoscono frammenti di bivalvi, echinidi, foraminiferi bentonici ed alghe calcaree. il deposito lito-bioclastico basale passa gradualmente verso l’alto a strati e banchi calcarenitici e calciruditici dal tipico colore giallo-ocra a luoghi clinostratificati e costituiti in prevalenza da un deposito bioclastico con tessitura grainstone/rudstone in cui si riconoscono frammenti di gusci, abrasi e in alcuni casi ben selezionati, di bivalvi, echinidi, gasteropodi, foraminiferi bentonici e rodoliti. la frazione terrigena, costituita da elementi litici millimetrici o centimetrici derivanti dall’erosione del substrato, è presente, ma tende gradualmente a diminuire verso l’alto. le superfici di strato sono poco evidenti e delimitano strati e banchi di spessore variabile da 30 cm a 2÷3 metri con giacitura sub-orizzontale. la porzione superiore della calcarenite di gravina presenta caratteristiche di facies piuttosto omogenee. infatti, si riconoscono biocalcareniti e biocalciruditi intensamente bioturbate con tessitura packstone e più raramente grainstone costituite da abbondanti macrofossili, a luoghi intensamente bioerosi, tra cui lamellibranchi, briozoi, balani, alghe calcaree coralline (lithophyllum e lithothamnium), foraminiferi bentonici (abbondanti amphistegine ed elphidium) e planctonici. la frazione terrigena di tale deposito è molto scarsa o del tutto assente. nel complesso, le facies descritte indicano che questa formazione si è depositata in ambienti marini neritici che gradualmente evolvono verso l’alto dalla beachface alla shoreface in relazione ad una graduale tendenza all’approfondimento com’è evidenziato dalle strutture sedimentarie, dalla 146 fig. 2 carta e sezione geologica dell’area di studio. e’ riportato anche lo schema stratigrafico dei depositi del supersintema del tavoliere delle puglie (pleistocene medio-superiore). geologic map and section of the study area. the stratigraphic sketch of the tavoliere delle puglie supersynthem (middle-upper pleistocene) is shown. progressiva diminuzione della frazione terrigena derivante dall’erosione del substrato e dalla chiara tendenza fining upward. l’analisi micropaleontologica ha permesso di riconoscere la seguente associazione fossilifera di foraminiferi planctonici globigerinoides quadrilobatus, globigerina bulloides, globigerinoides ruber e neogloboquadrina acostaensis, attribuibile genericamente al pliocene medio-superiore (sprovieri, 1993). questi dati collimano con quelli di d’alessandro et al. (1979) che, nelle stesse aree di studio ed anche in aree limitrofe, hanno attribuito la calcarenite di gravina al pliocene medio-superiore sia per il contenuto macropaleontologico che per quello micropaleontologico. le argille subappennine (pliocene medio pleistocene inferiore) la formazione delle argille subappennine (azzaroli, 1968) è costituita da un complesso di depositi argillosi, sabbiosi e siltosi depositatosi tra il pliocene medio ed il pleistocene inferiore nel bacino della fossa l. spalluto & m. moretti 147 bradanica. le argille subappennine affiorano in un’area molto ristretta nel settore sud-occidentale del foglio 1:50.000 n° 396 san severo (fig. 2) per uno spessore di circa 1520 m, ma, va sottolineato, costituiscono il substrato delle numerose unità pleistoceniche in tutto il settore di avanfossa (fig. 2), come si ricava dalle stratigrafie di numerosi pozzi per acqua perforati nell’area. i principali caratteri litologici e sedimentologici sono osservabili solo in aree limitrofe, ma esterne al foglio stesso (aree poste a ovest, alto morfologico di torre fiorentina). in queste aree le argille subappennine sono costituite da strati e banchi di silt argillosi con spessori variabili da qualche decina di centimetri ad oltre un metro. litologicamente sono costituite da argille siltose fortemente bioturbate che si alternano ad argille marnose, silt e sabbie da fini a grossolane di colore grigio-scuro. nell’area di interesse per meglio caratterizzare le unità plio-pleistoceniche sono stati perforati tre pozzi a carotaggio continuo. in carota, le argille subappennine sono caratterizzate da alternanze centimetriche e decimetriche tra argille siltose, silt e sabbie fini di colore grigio scuro. la laminazione è generalmente piano-parallela, incrociata solo negli intervalli sabbiosi; la bioturbazione è molto diffusa e a luoghi oblitera completamente le strutture sedimentarie primarie. si rinvengono numerosi resti di bivalvi e serpulidi sia in frammenti che interi. i dati di profondità disponibili in letteratura (pozzo agip san severo 1 bis – agip, 1977; balduzzi et al., 1982; casnedi, 1982; sella et al., 1988) indicano che le argille subappennine presentano spessori variabili da poche decine di metri nel settore di tavoliere prossimo al gargano, fino ad uno spessore massimo di circa 1000 metri nel settore sud-occidentale dell’area di studio (fig. 2). lo spessore è condizionato dall’assetto tettonico profondo del substrato meso-cenozoico. i dati provenienti dagli affioramenti ed i caratteri sedimentologici desunti dalle carote permettono di interpretare le argille subappennine come il risultato della sedimentazione, essenzialmente silicoclastica, in ambienti marini di piattaforma esterna. tale indicazione conferma quanto desumibile in letteratura per aree limitrofe (g a l l i c c h i o et al ., 2002; d’a l e s s a n d r o & l a p e r n a , 2004). sulla base delle associazioni a nannofossili calcarei l’unità è riferibile al pleistocene inferiore, per la presenza di rare “medium” gephyrocapsa (sensu rio et al., 1990); l’associazione non consente una più precisa attribuzione biozonale ed è rappresentata principalmente da pseudoemiliania lacunosa (kamptner), calcidiscus leptoporus (m u r r a y & blackman), “small” gephyrocapsa (sensu rio et al., 1990), reticulofenestra spp., rare helicosphaera sellii bukry & bramlette. 3.2 evidenze di tettonica nell’intervallo pliocene medio – pleistocene inferiore oltre che dall’evoluzione stratigrafica, la tettonica connessa a questa fase di subsidenza è ben registrata anche da numerose faglie distensive la cui attività è sinsedimentaria rispetto alla deposizione della calcarenite di gravina (pliocene medio-superiore); nell’area ad ovest di apricena (località masseria zingari), la presenza di numerose sezioni stratigrafiche lungo tagli variamente orientati della nuova linea ferroviaria e di quella dismessa consente di seguire e mappare accuratamente i principali elementi strutturali; inoltre la presenza di affioramenti di depositi di età variabile dal miocene medio al pleistocene medio consente di datare in modo preciso l’attività di tali faglie. lungo i nuovi tagli della ferrovia è possibile osservare alcune faglie dirette ad attività sinsedimentaria in relazione alla deposizione della calcarenite di gravina (pliocene medio-superiore). si tratta di stretti semigraben (qualche decina di metri in ampiezza) che tagliano i calcari miocenici e presentano chiare strutture di “crescita” nella calcarenite di gravina (pieghe per propagazione di faglia). a luoghi, in corrispondenza di tali faglie, si osservano anche blocchi di calcari miocenici franati all'interno della calcarenite di gravina che probabilmente indicano la presenza di falesie instabili proprio fig. 3 esempio di tettonica distensiva connessa alla fase di subsidenza del pliocene – pleistocene inferiore. le faglie dirette tagliano localmente la calcarenite di gravina (pliocene medio-superiore), ma sono suturate dal subsintema di colle degli ulivi (pleistocene medio). example of the pliocene – lower pleistocene subsidence phase. extensional faults cut the calcarenite di gravina fm. and are suturated by the colle degli ulivi subsynthem. evidenze di neotettonica ... 148 lungo tali strutture tettoniche. l'attività sinsedimentaria di tali semigraben è testimoniata dal brusco aumento di spessore delle calcareniti plioceniche in corrispondenza delle faglie stesse. il rigetto imputabile all'attività pliopleistocenica sembra diminuire verso l'alto ed è comunque al massimo di pochi metri (5÷6 m il rigetto massimo osservato). le faglie descritte sono inoltre suturate dai depositi marini del pleistocene medio che si rinvengono in pinch-out sia sulla calcarenite di gravina che sui calcari miocenici (fig. 3). in corrispondenza del taglio della ferrovia dismessa sono stati osservati altri effetti di tettonica pliocenica. l'attività sinsedimentaria è testimoniata da intensi piegamenti negli strati della calcarenite di gravina, sia lungo i piani di faglia principali che lungo piani secondari. si osserva una faglia diretta principale (f1 in fig. 4) che mette in contatto tettonico i calcari del miocene e la calcarenite di gravina: il movimento è suggerito chiaramente dall’uncinatura verso l'alto degli strati di calcarenite di gravina; localmente si osservano anche bruschi aumenti di spessore degli strati della calcarenite pliocenica lungo tale faglia che testimoniano un’attività anche sinsedimentaria della stessa. alla faglia principale è però associata una faglia con chiari caratteri di rigetto inverso (si osservi l’uncinatura degli strati verso la faglia f2 in fig. 4). l'associazione di faglie dirette principali e faglie inverse “coniugate” viene spesso spiegata in termini di effetti locali di transtensione o transpressione lungo elementi strutturali con movimento essenzialmente trascorrente (fiori negativi o positivi). un’altra possibile interpretazione è legata all’osservazione che la tettonica distensiva su sistemi complessi formati da un substrato rigido sul quale è presente una copertura sedimentaria poco diagenizzata (si vedano i modelli proposti da withjack et al., 1990 e hardy & mcclay, 1999) porta alla formazione di strutture tettoniche molto simili a quelle osservate in affioramento (f1 ed f2 in fig. 4). in entrambi i casi si tratta di una evidenza di tettonica sinsedimentaria nella calcarenite di gravina che mostra chiari effetti di deformazione tettonica in condizioni di soft-sediment. infine un'ultima evidenza di tettonica sinsedimentaria è rappresentata dalla presenza di numerosi “filoni nettuniani” al contatto fra i calcari miocenici e la calcarenite di gravina (fig. 5). si tratta di profonde fratture distensive nel substrato rigido dei calcari miocenici (lunghe fino a 6 m) all'interno delle quali viene “risucchiata” la calcarenite di gravina. la deformazione è sempre sinsedimentaria (rispetto alla deposizione della calcarenite di gravina) in quanto il termine superiore si deforma in condizioni non-consolidate (soft-sediment deformation) ed interi strati vengono “risucchiati” e/o piegati dalla deformazione distensiva fragile del substrato. non sono invece state evidenziate strutture tettoniche con attività infrapleistocenica. 4. la fase di uplift del pleistocene medio superiore 4.1 dati stratigrafici i depositi delle argille subappenine sono delimitati al tetto da una serie di superfici erosive su cui poggiano fig. 4 a e b: tettonica sinsedimentaria pliocenica lungo la ferrovia dismessa (apricena). la faglia principale f1 è diretta (uncinatura verso l'alto degli strati di calcarenite di gravina) e presenta attività sinsedimentaria rispetto alla deposizione della calcarenite di gravina (piccole variazioni di spessore verso la faglia). alla faglia f1 principale è associata una faglia f2 a rigetto inverso (si osservino le uncinature). c: modello analogico di deformazione di una copertura sedimentaria poco diagenizzata al di sopra di un substrato rigido soggetto a distensione (da hardy & mcclay, 1999 modificato). si noti la formazione di faglie inverse (*). a and b: pliocene synsedimentary tectonics in the apricena area. master fault (f1) shows a normal displacement. the f2 fault shows a clear compressional displacement. c: results of laboratory experiments on extensional faults affecting a soft-sediment sedimentary cover (modified from hardy & mcclay, 1999). note the presence of reverse faults (*). l. spalluto & m. moretti depositi litologicamente e tessituralmente eterogenei attribuibili sia ad ambienti marini costieri che ad ambienti alluvionali. nel corso del rilevamento sono stati distinti sei differenti sintemi terrazzati distribuiti, dal più antico al più recente, a quote decrescenti (fig. 2): 6) sintema di masseria finamondo (pleistocene superiore); 5) sintema di motta del lupo (pleistocene superiore); 4) sintema di foggia (pleistocene superiore); 3) sintema di masseria la motticella (pleistocene medio – superiore?); b) subsintema di masseria de grossi; a) subsintema de il casone; 2) sintema di vigna bocola (pleistocene medio); b) subsintema di masseria pallante; a) subsintema di san severo; 1) sintema di cava petrilli (pleistocene medio); b) subsintema di masseria casillo; a) subsintema di colle degli ulivi. i tre sintemi più antichi (sintema di cava petrilli, sintema di vigna bocola e sintema di masseria la motticella) sono stati suddivisi in due subsintemi separati da una superficie di erosione che mette a contatto depositi marini che mostrano un trend regressivo ed i sovrastanti depositi in facies continentale alluvionale. i tre sintemi più recenti (sintema di foggia, sintema di motta del lupo e sintema di masseria finamondo) sono costituiti essenzialmente da successioni continentali. i tre subsintemi marini (subsintema di colle degli ulivi, subsintema di san severo e subsintema de il casone) hanno uno spessore di circa 30-35 m, affiorano in lembi nell’area di studio e, con la sola eccezione del subsintema di colle degli ulivi ben visibile in alcune trincee ferroviarie, i caratteri di facies sono stati osservati prevalentemente attraverso l’esecuzione di apposite perforazioni a carotaggio continuo. il subsintema di colle degli ulivi è costituito dal basso verso l’alto, da: alternanze tra argille con laminazione piano-parallela e sabbie a laminazione incrociata con intercalazioni di livelli ghiaiosi formati alla base da letti di clay-chips provenienti dall’erosione del substrato argilloso; sabbie con stratificazione incrociata formanti foresets progradanti verso ne e strette forme erosive canalizzate riempite da sabbie a stratificazione incrociata; alternanze fra conglomerati e sabbie con i conglomerati che aumentano in spessore, dimensioni dei ciottoli e frequenza verso l’alto dove mostrano forme canalizzate. l’insieme dei caratteri descritti indica che il subsintema di colle degli ulivi si è depositato in un ambiente marino transizionale di delta passante lateralmente ad ambienti di mare sottile. i corpi ghiaiosi caratterizzavano i canali attivi del delta e sfumavano lateralmente in corpi sabbiosi progradanti verso ne sui depositi prevalentemente argillosi di prodelta. la successione verticale e laterale delle facies indica chiaramente che il subsintema di colle degli ulivi mostra un trend regressivo. il subsintema di san severo ed il subsintema de il casone sono costituiti, dal basso verso l’alto, da: alternanze argilloso-sabbiose a luoghi con lamine piano-parallele, intensamente bioturbate e con abbondante contenuto in materia organica; sabbie giallastre ben selezionate e a luoghi bioturbati con interstrati siltoso-argillosi che aumentano in spessore e frequenza verso l’alto; argille brune e verdi bioturbate con rare lamine siltoso-sabbiose; argille verdastre con abbondante presenza di concrezioni calcaree di origine diagenetica, sabbie da medie a fini ben selezionate e a laminazione incrociata passanti in alto ad argille brunastre a laminazione piano-parallela. tutti i caratteri di facies indicano che tali subsintemi si sono depositati in ambienti marini costieri di baia più o meno protetta. si 149 fig. 5 dicchi nettuniani al contatto fra i calcari del miocene e la sovrastante calcarenite di gravina. sono rappresentati da fratture di forma conica impostate nel substrato miocenico riempite dalle sovrastanti calcareniti plioceniche. si noti la deformazione tipo “soft-sediment” nella calcarenite di gravina e la deformazione fragile del substrato miocenico. neptunian dykes at the contact between the miocene limestones formation and the overlying calcarenite di gravina formation. they are represented by large conical fractures in the miocene substratum which are filled by the overlying pliocene calcarenites; note the soft-sediment deformation in the calcarenite di gravina fm. and the extensional brittle deformation of the substratum. evidenze di neotettonica ... tratta di una successione marina e di transizione con un generale trend regressivo. la base trasgressiva è rappresentata da alternanze argilloso-siltoso-sabbiose deposte in shoreface superiore in una baia molto protetta e con scarsa circolazione costiera. la parte superiore è invece costituita da sabbie da grossolane a fini di ambienti relativamente più profondi (shoreface inferiore) in un contesto di baia aperta. verso l’alto si torna a condizioni di baia ristretta fino alle sabbie a laminazione incrociata ed alle argille brunastre che probabilmente rappresentano già ambienti di transizione al continentale. il subsintema di masseria casillo, il subsintema di masseria pallante ed il subsintema di masseria de grossi poggiano in erosione sui subsintemi marini sottostanti e presentano caratteri litologici molto simili tra loro. in particolare, sono costituiti da conglomerati poligenici con abbondante matrice sabbiosa rossastra. i ciottoli presentano una bassa selezione granulometrica ed il diametro massimo è prossimo a 30 cm. si presentano mal stratificati e, solo a luoghi, è possibile riconoscere superfici erosive canalizzate. l’ambiente di sedimentazione è riferibile in base ai dati sedimentologici ad una piana braided. lo spessore massimo di questi subsintemi è nell’ordine dei 10-15 m. la base dei tre sintemi più recenti (sintema di foggia, sintema di motta del lupo e sintema di masseria finamondo non è mai visibile in affioramento, rappresentata, come si ricava dai dati di pozzo per i sintemi di motta del lupo e masseria finimondo, da un paio di metri di depositi marini (sabbie fini ben selezionate con abbondante contenuto in microfossili). verso l’alto, questi depositi sono costituiti da: alternanze tra ghiaie poligeniche con ciottoli di dimensioni centimetriche e sabbie con associata terra rossa; argille brune con lamine piano-parallele e con intercalazioni siltososabbiose a luoghi con ripples asimmetrici e laminazione incrociata a basso angolo ed abbondante contenuto in terra rossa; argille nerastre cementatissime prive di strutture sedimentarie e silt con abbondanti concrezioni calcaree di origine diagenetica. i residui di lavato contengono rari frammenti di macrofossili, ostracodi, oogoni di alghe carofite o rarissimi foraminiferi rotti ed abrasi ed in alcuni casi sono risultati sterili. questi sintemi mostrano un trend chiaramente regressivo: su sabbie marine, si rinvengono sia argille, sabbie e ghiaie di ambiente alluvionale con condizioni idrodinamiche anche di moderata energia, che argille brune e verdi di palude e/o di laguna ristretta in cui si potevano depositare grandi quantità di materia organica. 4.2 evidenze di tettonica nell’intervallo pleistocene mediosuperiore l’eventuale presenza di strutture tettoniche ad attività sinsedimentaria associate a questa fase sono meno documentabili a causa della mancanza di estesi affioramenti dei depositi medio e supra pleistocenici. ciononostante, i subsintemi marini più antichi e meglio affioranti (subsintema di colle degli ulivi e subsintema di san severo) mostrano chiari indizi di tettonica sinsedimentaria e sono dislocati nel settore nord-occidentale dell’area analizzata (area a n e no di apricena). in località cava di nunzio (fig. 6) è stata documentata la presenza di una faglia diretta subverticale che taglia per intero la successione marina di transizione dei depositi del subsintema di colle degli ulivi con un rigetto di circa 20 m: la sua attività è chiaramente successiva alla sedimentazione della stessa unità marina (pleistocene medio). l’andamento è circa e-o e non sono stati osservati indicatori cinematici. ad ovest dell’abitato di apricena, lungo la nuova trincea ferroviaria, sono visibili due faglie subverticali a rigetto diretto (rigetto massimo misurato nell’ordine dei 6-7 m) che interessano il subsintema di san severo (pleistocene medio). la faglia diretta più meridionale mette in contatto tettonico le facies sabbiose che caratterizzano la porzione basale dell’unità con le argille brune e verdi che si rinvengono nella porzione centrale e superiore della successione (fig. 7). anche in questo caso l’andamento delle faglie è e-o e l’attività è postpleistocene medio. 5. deduzioni tettoniche e paleogeografiche i dati stratigrafici e tettonici esposti permettono di delineare i punti principali dell’evoluzione sedimentaria e strutturale plio-pleistocenica di questo settore del tavoliere delle puglie nel plio-pleistocene. le evidenze della tettonica connessa alla fase di subsidenza dell’avampaese apulo (pliocene medio150 fig. 6 evidenze di tettonica durante la fase di sollevamento del pleistocene medio-superiore. evidences of tectonics during the middle-upper pleistocene uplift phase. l. spalluto & m. moretti pleistocene inferiore) sono registrate dal punto di vista stratigrafico nell’area di interesse dal progressivo annegamento di vasti settori dell’avampaese apulo. il trend trasgressivo legato a questa fase è registrato nell’area di studio dalla sedimentazione della calcarenite di gravina che mostra una chiara evoluzione del tipo fining/deepening upward nella successione verticale delle facies. la fase di subsidenza continua anche nel pleistocene inferiore ed è marcata dalla sedimentazione delle argille subappennine che, nell’area di studio, è costituita da fanghi e silt emipelagici attribuibili ad ambienti di piattaforma esterna. queste ultime raggiungono spessori notevoli (fino a 1000 m da dati di pozzo) al di sopra della monoclinale regionale che si immerge al di sotto dell'appennino. dal punto di vista strutturale, la subsidenza è documentata da faglie dirette orientate circa est-ovest con attività sinsedimentaria in relazione alla deposizione della calcarenite di gravina. le strutture riconosciute interessano esclusivamente la calcarenite di gravina senza trasferirsi alle sovrastanti argille subappennine: tale dato sembra indicare che gli effetti della tettonica distensiva nel settore in esame si risentano solo nella fase di incipiente passaggio da area di avampaese ad area di avanfossa subsidente. l'insieme dei caratteri stratigrafici e strutturali esposti per il supersintema del tavoliere delle puglie mostra che esso costituisce un insieme complesso di depositi marini e continentali che segnano l’evoluzione stratigrafico-strutturale di questo settore del tavoliere a partire dal pleistocene medio fino all’attuale. in particolare, nell'area di studio la fase di sollevamento è segnata dalla presenza di sintemi e subsintemi terrazzati in facies marina costiera e continentale che marcano la graduale riemersione di questo settore di transizione fra l'avampaese apulo e l’avanfossa. il progressivo sollevamento dell'area in esame può essere desunto oltre che dalla distribuzione altimetrica dei depositi, anche dallo studio dei caratteri evolutivi dei singoli sintemi o subsintemi che costituiscono il supersintema del tavoliere delle puglie. il subsintema di colle degli ulivi è rappresentato da corpi deltizi progradanti verso ne, mentre i subsintemi di san severo e del casone si sviluppano in ambienti di bassa energia tipo baia. tale dato indica la presenza di una paleolinea di costa orientata approssimativamente no-se nel caso del subsintema di colle degli ulivi. viceversa, i depositi marini dei subsintemi più recenti (subsintema di san severo e subsintema de il casone) si depositavano in un’area protetta tipo baia che, dal punto di vista paleogeografico, era rappresentata da linee di costa parallele all’attuale golfo di manfredonia distribuite via via a quote decrescenti. inoltre analizzando e confrontando i caratteri litologici dei depositi marini e continentali è possibile affermare che i corpi deltizi progradanti del subsintema di colle degli degli ulivi erano associati ad un corso d’acqua (il paleofortore secondo aucelli et al., 1997) che aveva un reticolo idrografico ed un’area di alimentazione che si estendevano in aree interne del subappennino dauno. i clasti del subsintema di colle degli ulivi sono infatti poligenici e sono rappresentati da una gran varietà di litologie (rocce intrusive, arenarie, calcari, selci, ecc.) alcune delle quali sono presenti unicamente nel flysch di san bartolomeo (che non affiora nel settore esterno del subappennino dauno). viceversa tutti i depositi alluvionali terrazzati dei sintemi o subsintemi più recenti contengono unicamente clasti che provengono dal settore esterno dell’appennino (con area di alimentazione coincidente con quella degli attuali corsi d’acqua) nel quale affiorano prevalentemente unità calcaree (flysch di faeto e flysch rosso). l’insieme di questi dati mostra che nel pleistocene medio vi è stato un intenso sollevamento dell’area posta a nord del settore analizzato. al sollevamento di quest’area sono probabilmente associate le faglie che sono state descritte precedentemente nei depositi del pleistocene medio-superiore. tale sollevamento, che coincide parzialmente con quello descritto da aucelli et al. (1997) in settori limitrofi all’area qui analizzata, deve essere avvenuto infatti lungo strutture tettoniche orientate circa e-o ed in grado di isolare un settore settentrionale direttamente connesso all’adriatico (l’attuale valle del fortore), da uno meridionale tipo baia sviluppatosi parallelamente all’attuale golfo di manfredonia. la distribuzione altimetrica dei sintemi appartenenti al supersintema del tavoliere delle puglie mostra che il sollevamento caratterizza tutti i depositi dal pleistocene medio all’attuale. tale considerazione ricalca quanto ricavato, in un settore del tavoliere a so dell’area qui considerata, da gallicchio et al. (2002). nel settore pedemontano del tavoliere infatti, il supersintema del tavoliere delle puglie è caratterizzato solo da depositi continentali (attribuibili a sistemi alluvionali di conoide e braided): i depositi di conoide più antichi sembrano svilupparsi su ampie superfici che si estendono ininterrottamente, da o verso e, dalla catena fino all’area di lucera; nel tempo ciascun alveo si è approfondito confinando via via sistemi di conoide passanti distalmente a sistemi di tipo braided in valli allungate all’incirca e-o. nell’area rappresentata nel foglio san severo affiorano i sintemi meno elevati e più recenti appartenenti a questo supersintema. la differenza sostanziale rispetto al settore pedemontano descritto precedente151 fig. 7 faglie connesse al sollevamento. faglia diretta che taglia il subsintema di san severo (pleistocene medio). faults related with the uplift phase. extensional fault that cuts the san severo subsynthem (middle-pleistocene). evidenze di neotettonica ... mente risiede nella presenza (nei sintemi più antichi affioranti) dei depositi marini. nel settore pedemontano del tavoliere i depositi marini sono stati erosi (se ne ritrovano tracce nei clasti dei depositi continentali dei sintemi più antichi). nel settore orientale del tavoliere delle puglie (ricadente nell’area qui analizzata) i depositi marini sono stati invece localmente preservati dall’erosione. tale differenza potrebbe essere connessa sia al maggiore spessore che i depositi marini potevano avere in questo settore sia al presumibile maggior grado di erosione che essi dovevano subire nel settore pedemontano (a parità di tassi di sollevamento e di sedimentazione). inoltre, la presenza di sintemi continentali più antichi ed a quote maggiori ed il fatto che alcuni subsintemi continentali poggino sia sulle argille subappennine che sui subsintemi marini porta a ritenere che questi ultimi probabilmente si depositavano all’interno di valli incise, durante periodi di ingressione marina in un trend generale regressivo indotto dal sollevamento. 6. conclusioni nel corso dei rilevamenti per la nuova carta geologica d'italia (scala 1:50.000), foglio n° 396 "san severo", sono stati riconosciuti numerosi elementi strutturali con evidenze di attività neotettonica (pliocene medio pleistocene superiore). i caratteri della deformazione tettonica ed i vincoli stratigrafici hanno permesso di riconoscere due distinte fasi di tettonica distensiva: una relativa al pliocene medio – pleistocene inferiore, l'altra attiva a partire dal pleistocene medio. le strutture tettoniche connesse alla subsidenza del pliocene medio – pleistocene inferiore confermano quanto noto in letteratura per l’area di avanfossa a sud dell’ofanto. in particolare gli effetti di tettonica sinsedimentaria nella calcarenite di gravina presentano caratteri molto simili a quelli descritti da tropeano et al. (1994) lungo il margine sud-occidentale delle murge (area a so di matera). il sollevamento, in atto a partire pleistocene medio, è registrato dai depositi marini e continentali appartenenti al supersintema del tavoliere delle puglie che si rinvengono, dal più antico al più recente, a quote via via decrescenti sul livello del mare. il sollevamento è accompagnato dall'attività di faglie dirette, documentata nel settore nord-occidentale dell'area investigata. lo studio di dettaglio della stratigrafia dei depositi del pleistocene medio-superiore ha consentito di evidenziare non solo la presenza di faglie con attività successiva al pleistocene medio, ma anche di valutare con buona approssimazione i relativi rigetti. ringraziamenti si ringraziano: piero pieri e giustino ricchetti per il coordinamento e per la direzione scientifica dei lavori di rilevamento geologico del foglio 396 “san severo” (progetto c.a.r.g. puglia); patrizia maiorano e fabrizio lirer per le analisi biostratigrafiche delle unità plio-pleistoceniche; marcello tropeano e vincenzo festa per le proficue discussioni sul tema della tettonica plio-pleistocenica; i due referees per gli utili suggerimenti. lavoro pubblicato con fondi di ateneo miur ex 60% 2003-2004 (resp. l. sabato). bibliografia citata aucelli p.p.c., cinque a. & robustelli g. 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(2002) i depositi continentali terrazzati (pleistocene medio-superiore) nel settore pedemontano del tavoliere delle puglie. fascicolo degli abstract della ix riunione del gruppo di sedimentologia del cnr, pescara, 21-22/10/2002, 46-47. gambini, r. & tozzi m. (1996) tertiary geodynamic evolution of the southern adria microplate. terra nova, 8, 593-602. hardy s. & mc clay k. (1999) kinematic modelling of extensional fault-progagation folding. journ. of struct. geol., 21, 695-702. jacobacci a., malatesta a., martelli g. & stampanoni g. (1967) note illustrative della carta geologica d’italia alla scala 1:100.000 foglio 163 lucera. 48 pp. merla g., ercoli a. & torre d. (1969) note illustrative della carta geologica d'italia alla scala 1: 100.000. foglio 164 "foggia", 22 pp. morsilli m., de cosmo p.d., bosellini a., luciani v. 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(1980) principali caratteri geologici e morfologici delle murge. murgia sotterranea, bollettino gruppo speleo martinese, martina franca, 2, 1319. pieri p., sabato l. & tropeano m. (1996) significato geodinamico dei caratteri deposizionali e strutturali della fossa bradanica nel pleistocene. mem. soc. geol. it., 51, 501-515. pomar l. & tropeano m. (2001) the calcarenite di gravina formation in matera (southern italy)new insights for corse-grained large scale, cross-bedded bodies encased in offshore deposits. aapg bull., 85, 661-689. ricchetti g. (1967) lineamenti geologici e morfologici della media valle del fiume bradano. bol. soc. geol. it., 86, 607-622. ricchetti g. ( 1980) contributo alla conoscenza strutturale della fossa bradanica e delle murge. bol. soc. geol. it., 99, 421-430. ricchetti g., ciaranfi n., luperto sinni e., mongelli f. e pieri p. (1988) geodinamica ed evoluzione sedimentaria e tettonica dell'avampaese apulo. mem. soc. geol. it., 41, 57-82. rio d., raffi i. & villa g. (1990) pliocene-pleistocene distribution patterns in the western mediterranean. in kastens k.a., mascle j. et alii, (eds.). proceeding of odp, scient. results, 107, 513-533. sella m., turci c. & riva a. (1988) sintesi geopetrolifera della fossa bradanica (avanfossa della catena appenninica meridionale). mem. soc. geol. it., 41, 87-107. selli r. (1962) il paleogene nel quadro della geologia dell'italia centro-meridionale. mem. soc. geol. d'it., 3, 737-789. spalluto l. (2004) la piattaforma apula nel gargano centro-occidentale: organizzazione stratigrafica ed assetto della successione mesozoica di piattaforma interna. tesi di dottorato in scienze della terra. università degli studi di bari, 173 pp. sprovieri r., (1993) mediterranean pliocene biochronology: an high resolution record based on quantitative planktonic foraminifera distribution. riv. ital. paleontol. stratigr., 98, 61-100. tinti s., maramai a. & favali p. (1995) the gargano promontory: an important italian seismogenic-tsu153evidenze di neotettonica ... namigenic area. marine geology, 122, 227-241. tondi e., piccardi l., cacon s., kontny b. & cello g. (2005) structural and time constraints for dextral shear along the seismogenic mattinata fault (gargano, southern italy). journal of geodynamics, 40, 134-152. tropeano m., marino m. & pieri p. (1994) evidenze di tettonica distensiva plio-pleistocenica al margine orientale della fossa bradanica. l’horst di zagarella. il quaternario, 7 (2), 597-606. tropeano m. & sabato l. (2000) response of pliopleistocene mixed bioclastic-lithoclastic temperate-water carbonate systems to forced regression: the calcarenite di gravina formation, puglia, se italy. in: “sedimentary responses to forced regression” (d.hunt & r.l. gawthorpe, eds.), geol. soc. london, spec. publ., 171, 217-243. tropeano m., sabato l. & pieri p. (2002) filling and cannibalization of a foredeep: the bradanic trough (southern italy). in “sediment flux to basins: causes, controls and consequences” (s.j. jones and l.e. frostick, eds.), pp. 55-79. geol. soc. london, spec. publ., 191, 55-79. valduga a. (1973) fossa bradanica. in geologia dell’italia, a cura di desio a.., utet, 692-695. w i t h j a c k m.o., o l s o n j. & p e t e r s o n e. (1990) experimental models of extensional forced folds. a.a.p.g. bull., 74, 1038-1045. 154 ms. ricevuto il 6 giugno 2006 testo definitivo ricevuto il 17 ottobre 2006 ms. received: june 6, 2006 final text received:october 17, 2006 l. spalluto & m. moretti dinamica recente ed attuale degli alvei fluviali in italia: stato dell'arte e prospettive nicola surian1 & massimo rinaldi2 1dipartimento di geografia, università di padova, via del santo 26, 35123 padova 2dipartimento di ingegneria civile e ambientale, università di firenze, via s. marta 3, 50139 firenze e-mail: nicola.surian@unipd.it riassunto: surian & rinaldi, dinamica recente ed attuale degli alvei fluviali in italia: stato dell'arte e prospettive. (it issn 0394-3356, 2008). lo scopo del presente lavoro è quello di fare il punto sulle ricerche che riguardano le variazioni morfologiche degli alvei in italia, evidenziando anche gli aspetti cruciali su cui le ricerche dovrebbero concentrarsi nell'immediato futuro. il lavoro si basa su di un'analisi bibliografica di settanta pubblicazioni e sulle ricerche condotte nell'ambito di un progetto nazionale (prin 2005). considerando la distribuzione temporale delle pubblicazioni riguardanti le variazioni morfologiche degli alvei in italia si può notare un aumento del numero di pubblicazioni nel corso del periodo in esame (1963 2007), ma comunque un numero relativamente basso di pubblicazioni per anno. dal punto di vista metodologico si osserva un prevalente approccio qualitativo fino alla fine degli anni '90, quindi l'impiego di approcci più quantitativi, in particolare per la ricostruzione della variazione temporale di parametri come la larghezza dell'alveo o la quota del fondo. la maggior parte dei fiumi italiani è stata interessata da simili variazioni per quanto riguarda la sequenza temporale, mentre l'intensità delle variazioni è dipesa da vari fattori, come, ad esempio, la morfologia originale dell'alveo. inizialmente si è verificata una fase d'incisione e restringimento, iniziata verso la fine del xix sec. e particolarmente intensa fra gli anni '50 e gli anni '80-'90 del xx sec. quindi, negli ultimi 15-20 anni, processi di allargamento dell'alveo sono stati osservati nella maggior parte dei casi. queste modificazioni morfologiche sono imputabili principalmente ad una serie di interventi antropici, quali il prelievo di sedimenti, la costruzione delle dighe, interventi di canalizzazione e variazioni di uso del suolo. un significativo miglioramento nella comprensione della dinamica degli alvei è derivato dalle ricerche più recenti, soprattutto attraverso la ricostruzione delle variazioni temporali della larghezza dell'alveo e più specifiche analisi sulle cause delle variazioni, ma vari aspetti richiedono ad oggi delle indagini più approfondite. un punto cruciale è rappresentato dalle variazioni altimetriche, sia nel medio che nel breve termine. per le variazioni nel medio termine, in mancanza di adeguati rilievi topografici, è determinante ricorrere a specifici rilievi geomorfologici dell'alveo, mentre per le variazioni più recenti è auspicabile l'impiego di tecniche quali gps, lidar e fotogrammetria digitale. infine si sottolinea l'importanza di trasferire le conoscenze acquisite con queste ricerche nella gestione e riqualificazione degli alvei. abstract: surian & rinaldi, present and recent dynamics of river channels in italy: state of the art and perspectives. (it issn 03943356, 2008). during the last centuries, and particularly in the second half of the 20th century, many fluvial systems have been significantly affected by human interventions (e.g. dams, sediment mining and channelization). such interventions have effects on flows, sediment regime and channel morphology, causing channel adjustments that are generally much larger than those that could be expected from natural channel evolution. for instance, most italian rivers have experienced considerable channel adjustments in the last decades, e.g. channel incision up to 10 m or more and channel narrowing up to 85-90 %. the aim of this work is to review the present state of knowledge on channel adjustments in italian rivers and to analyse research needs and perspectives. the work is based on a review of published studies (seventy papers have been collected and analysed) and on the research carried out within a national project (prin 2005) over the last two years. the first studies on channel adjustments in italian rivers date back to the beginning of the 1960s. considering the distribution of publications from such a period to the present (2007), an increase can be observed in the number of publications through time, however the number of publications remains quite low in each year (the highest value, 7 papers, was reached in 1994). concerning the methodologies used in these studies, a qualitative approach was dominant up to the end of the 1990s, then a more quantitative approach. the latter has implied, for instance, the reconstruction of temporal trends for channel parameters such as channel width and bed elevation. most italian rivers have experienced almost the same processes as for temporal trends, though the magnitude of adjustments varies according to several factors (e.g. initial channel morphology). initially, river channels underwent a long phase of narrowing and incision, which started in the late 19th century and was very intense after the 1950s. then, during the last 15-20 years, channel widening has become the dominant process in several cases. such channel changes have been induced mainly by a range of human interventions, specifically sediment mining, dam construction, channelization works and land use changes (e.g. reforestation). a significant advance in the understanding of channel adjustments was obtained recently as for the reconstruction of evolutionary trends (in particular trends of channel width) and causes of channel adjustments, but several issues will require more efforts in the future. one crucial point will be, for instance, the analysis of past and present bed level adjustments. reconstruction of past trends, in the absence or scarcity of topographic surveys, will need specific geomorphological field surveys, whereas the analysis of present trends should be supported by recent topographic technologies, such as gps, lidar and digital photogrammetry. last, but not least, there should be an increasing transfer and application of the results to river management. in fact, it is becoming more and more established among fluvial scientists and practitioners that knowledge of channel evolution in the medium-short term is a key ingredient for the sustainable management of fluvial systems. parole chiave: alvei fluviali, variazioni morfologiche degli alvei, impatto antropico. keywords: alluvial channels, channel adjustments, human impact. il quaternario italian journal of quaternary sciences 21(1b), 2008 233-240 234 n. surian & m. rinaldi 1. introduzione nel corso degli ultimi secoli, ed in particolar modo negli ultimi 50-60 anni, la morfologia e la dinamica della maggior parte dei fiumi italiani hanno subito delle profonde modificazioni, soprattutto a causa di vari interventi antropici (ad esempio costruzione di dighe, prelievo di sedimenti dagli alvei, interventi di canalizzazione, variazioni di uso del suolo). tali interventi hanno infatti modificato il regime dei deflussi e delle portate solide, oltre ad altri aspetti, come la mobilità laterale, fondamentali nella dinamica di un alveo fluviale. l'entità delle variazioni subite dagli alvei è stata considerevole, in quanto in molti casi ha comportato una vera e propria trasformazione morfologica, ossia una modificazione della configurazione planimetrica (ad esempio da un alveo a canali intrecciati ad un alveo di tipo “wandering” o, addirittura, a canale singolo). i processi più diffusi sono stati il restringimento e l'incisione dell'alveo. la larghezza dell'alveo ha subito generalmente una riduzione superiore al 50 %, fino a valori dell' 85-90 %, mentre l'abbassamento del fondo è stato dell'ordine di alcuni metri ma, localmente, anche di 10-12 m (surian & ri n a l d i, 2003; su r i a n et al., 2008a). generalmente queste modificazioni si sono realizzate nel corso di pochi decenni. simili variazioni morfologiche dell'alveo si sono verificate anche in corsi d'acqua di altri paesi europei ed extra-europei, ma raramente l'intensità dei processi è stata così elevata come nei corsi d'acqua italiani (wi l l i a m s , 1978; wi l l i a m s & wo l m a n, 1984; si m o n, 1989; xu ji o n g x i n, 1997; se a r & ar c h e r, 1998; winterbottom, 2000; liebault & piegay, 2001; lu et al., 2007). infatti se non sono rari fenomeni di restringimento come quelli osservati nei fiumi italiani, sono poco frequenti fenomeni di incisione dell'ordine di 10-12 m. le ricerche condotte in ambito nazionale ed internazionale sulle variazioni morfologiche degli alvei hanno lo scopo di quantificare queste variazioni, ma soprattutto di comprenderne i processi e le cause. alcuni aspetti cruciali in queste ricerche sono: a) la ricostruzione temporale delle modificazioni, che implica non solo una valutazione quantitativa della modificazione morfologica, ma anche una valutazione dell'evoluzione temporale del processo; b) l'individuazione delle cause, ossia una dettagliata analisi delle possibili cause, naturali ed antropiche, e dei loro effetti sulle portate liquide, sulla portata solida e sulla morfologia dell'alveo; c) l'analisi delle relazioni spazio-temporali fra cause e variazioni morfologiche. un ulteriore obiettivo della ricerca deve essere quello di fare delle previsioni sull'evoluzione futura di un alveo fluviale instabile. tali previsioni, che si basano sulla conoscenza della dinamica fluviale nel breve e medio periodo, sono infatti fondamentali per la gestione e riqualificazione di un corso d'acqua (do w n s & gregory, 2004; rinaldi, 2006; habersack & piegay, 2008). lo scopo del presente lavoro è quello di fare il punto sulle ricerche che riguardano le variazioni morfologiche degli alvei in italia, evidenziando anche gli aspetti cruciali su cui le ricerche dovrebbero concentrarsi nell'immediato futuro. le considerazioni esposte di seguito si basano sull'analisi bibliografica di settanta pubblicazioni e sulle ricerche condotte nell'ambito di un progetto nazionale (prin 2005 “dinamica recente ed attuale di alvei fluviali in italia centro-settentrionale: tendenze evolutive, cause ed implicazioni applicative”) conclusosi recentemente (gennaio 2008). il lavoro prende spunto da una precedente sintesi sull'argomento (surian & rinaldi, 2003), alla quale si rimanda per alcuni approfondimenti, e vuole pertanto mettere in evidenza anche i progressi di questi ultimi anni. 2. stato de ll'arte: la ric erca in ital ia sulle variazioni morfologiche degli alvei le seguenti considerazioni derivano dall'analisi dei lavori esistenti sull'argomento. sono state reperite e consultate 70 pubblicazioni che comprendono un intervallo di oltre 40 anni (1963-2007). l'elenco completo delle pubblicazioni consultate è riportato in bibliografia. la distribuzione temporale di queste pubblicazioni mostra come, a partire dagli '60 del secolo scorso (si veda ad esempio ro v e r i, 1965; pe l l e g r i n i & ro s s i, 1967) fino ad oggi, ci sia stato un crescente numero di ricerche (fig. 1). negli anni '60 e '70 le pubblicazioni sono state molto limitate, rispettivamente 4 e 5, quindi 11 negli anni '80, 33 negli anni '90 e 17 nel periodo 2000-2007. nonostante l'incremento di pubblicazioni registrato negli ultimi 15-20 anni, il numero complessivo di pubblicazioni nell'intero periodo indica che si tratta di un tema di ricerca che ha suscitato un certo interesse, senza però raggiungere un vera e propria affermazione e collocazione in ambito nazionale. l'analisi bibliografica consente anche alcune considerazioni sui gruppi di ricerca (o i singoli ricercatori) coinvolti e sulla tipologia dei progetti nei quali si inseriscono le indagini sulle variazioni morfologiche degli alvei. alcune sedi universitarie (camerino, firenze, modena, padova, parma, pavia, perugia) ed il cnrfig.1 distribuzione temporale delle pubblicazioni riguardanti le variazioni morfologiche degli alvei in italia. temporal distribution of the publications regarding channel adjustments in italian rivers. irpi di torino risultano aver affrontato queste ricerche con una certa continuità temporale. per quanto riguarda la tipologia di progetti, la maggior parte delle pubblicazioni sono il risultato di singole iniziative ad eccezion e d el le ri cer ch e ch e c on fl u iv an o n el p ro ge t t o finalizzato “conservazione del suolo” (sottoprogetto “dinamica fluviale”) (pellegrini et al., 1979b; castiglioni & pe l l e g r i n i, 1981a; 1981b), finanziato dal cnr, e di quelle connesse al progetto nazionale sopra citato (prin 2005), del quale cominciano ora ad essere pubblicati i primi risultati (surian & cisotto, 2007; pellegrini et al., 2008; ri n a l d i et al., 2008; su r i a n et al, 2008a; 2008b). da un punto di vista metodologico le ricerche si sono basate fondamentalmente su osservazioni in campo, analisi di cartografia storica, di fotografie aeree e di rilievi topografici. il cambiamento più significativo, percepibile solo nei lavori più recenti (ad esempio rinaldi et al., 2005), è stato probabilmente l'impiego dei gis che consentono un'analisi della cartografia storica e delle fotografie aeree molto più accurata e certamente più aggiornabile nel tempo. come già evidenziato in un precedente lavoro di sintesi (su r i a n & ri n a l d i, 2003), complessivamente le ricerche sono state poco quantitative, mancando ad esempio, nella maggior parte dei casi, ricostruzioni temporali delle variazioni morfologiche. ciò che emerse nel lavoro appena citato era la quasi totale assenza di ricostruzioni della variazione temporale di parametri come la larghezza dell'alveo o la quota del fondo e, pertanto, la definizione di precise relazioni fra le variazioni morfologiche e le relative cause. alcuni recenti lavori di sintesi, nei quali sono stati analizzati i dati relativi a più corsi d'acqua, hanno messo in evidenza la presenza di modificazioni morfologiche e processi molto simili nei fiumi italiani (rinaldi, 2003; su r i a n & ri n a l d i, 2003; 2004; su r i a n, 2006). le variazioni che accomunano gli alvei fluviali sono un restringimento (in alcuni casi anche dell' 85-90 %) ed un abbassamento del fondo (in alcuni casi oltre i 10 m) molto marcati. tali processi si sono manifestati in alcuni corsi d'acqua a partire dal xix secolo, ma sono stati molto intensi per un periodo relativamente breve, ossia tra gli anni '50 e gli anni '80-'90 del secolo scorso. le cause di variazioni così intense nella morfologia degli alvei sono state individuate nel prelievo di sedimenti dagli alvei, generalmente il fattore più rilevante, nella costruzione di dighe, in vari interventi di canalizzazione, in variazioni di uso del suolo a scala di bacino (in particolare l'aumento della copertura boschiva) e nelle sistemazioni idraulico-forestali. mentre la fase principale di aggiustamento, che ha comportato il restringimento e l'incisione degli alvei, è stata documentata in tutti i lavori, la successiva fase, cominciata generalmente alla fine degli anni '80 o nei primi anni '90, è stata individuata ed analizzata solo nelle ultime ricerche (su r i a n & ri n a l d i, 2004; ri n a l d i e t a l., 2005; su r i a n, 2006; ri n a l d i & si m o n c i n i, 2006; su r i a n & ci s o t t o, 2007). questa fase più recente (ultimi 15-20 anni) è stata caratterizzata in molti corsi d'acqua da un riallargamento dell'alveo e da stabilità del fondo o da aggradazione. tali processi non hanno comunque “compensato” le variazioni indotte dalla fase preced e n t e . 235dinamica recente ed attuale ... 3. ricerche recenti e prospettive future come accennato in precedenza, si è ultimamente concluso un progetto nazionale incentrato sulle variazioni morfologiche degli alvei in italia (prin 2005 “dinamica recente ed attuale di alvei fluviali in italia centro-settentrionale: tendenze evolutive, cause ed implicazioni applicative”). il progetto, che ha coinvolto tre sedi universitarie (firenze, padova e pavia) ed il cnr-irpi di torino, si poneva i seguenti obiettivi: 1. revisione delle metodologie comunemente impiegate per l'analisi delle variazioni morfologiche degli alvei fluviali. alla luce degli studi realizzati sui fiumi italiani, è infatti auspicabile definire quali parametri morfologici utilizzare e come questi debbano essere misurati, in modo tale da rendere omogenei i dati provenienti da differenti casi di studio. 2. in riferimento al punto precedente, messa a punto di una metodologia di rilevamento sul terreno che consenta, soprattutto in assenza di dati altimetrici, di valutare le tendenze evolutive nel breve e medio termine. 3. disponibilità di un maggior numero di casi di studio ben documentati rispetto a quelli esistenti (surian & rinaldi, 2003; 2004), ossia di casi di studio per i quali si disponga delle variazioni temporali di alcuni parametri morfologici dell'alveo, quali quota del fondo, larghezza, ecc. 4. monitoraggio e analisi della dinamica recente (ultimi 15-20 anni) ed in atto negli alvei fluviali. 5. affinamento e sviluppo degli schemi/modelli evolutivi recentemente proposti da su r i a n & ri n a l d i ( 2 0 0 3 ; 2004), al fine di definire un modello concettuale in grado di descrivere le tendenze evolutive dei fiumi italiani. 6. individuazione delle cause, antropiche o naturali, che hanno determinato le variazioni morfologiche degli alvei e dei rapporti temporali di causa-effetto. 7. previsione, seppure qualitativa, dell'evoluzione futura degli alvei fluviali; ciò sulla base sia delle tendenze evolutive passate ed in atto, sia di differenti scenari di gestione delle risorse (in particolare dei sedimenti e di uso del suolo) e di cambiamenti climatici. 8. valutazione delle ricadute applicative della dinamica fluviale recente ed in atto; in particolare i riflessi sulla gestione dei corsi d'acqua (manutenzione degli alvei) e sui possibili interventi di riqualificazione fluviale. sulla base dei lavori finora pubblicati o in corso di pubblicazione (ri n a l d i & si m o n c i n i, 2006; su r i a n & ci s o t t o, 2007; pe l l e g r i n i et al., 2008; ri n a l d i et al. , 2008; rinaldi, 2008; surian et al., 2008a; 2008b) si ritiene che per alcuni degli aspetti appena elencati c'è stato un sostanziale avanzamento nelle conoscenze, mentre per altri il contributo del progetto è stato più limitato. riguardo agli aspetti metodologici sono stati fatti progressi su vari fronti (analisi storica da cartografia, foto aeree e immagini satellitari, analisi dei rilievi topografici, rilevamento geomorfologico in campo). ad esempio si è posta molta attenzione nella valutazione degli errori associati alla stima dei vari parametri (ad esempio larghezza dell'alveo, grado d'intrecciamento, quota del fondo), e si è giunti alla definizione di procedure che debbono essere non solo accurate ma anche riproducibili. novità importanti sono state introdotte anche per il rilevamento geomorfologico in campo, in quanto sono state definite una serie di misure ed osservazioni finalizzate alla definizione delle tendenze evolutive di un alveo. questi aspetti relativi al rilevamento geomorfologico e all'utilizzo di apposite schede, sono illustrati in un articolo contenuto in questo volume (rinaldi, 2008). da parte dei ricercatori coinvolti nel progetto prin 2005 è prevista comunque una pubblicazione complessiva che riassuma tutti questi aspetti metodologici, in modo tale da fornire delle “linee guida” per lo studio delle variazioni morfologiche degli alvei. il numero di casi di studio affrontati nel progetto amplia in modo significativo le conoscenze pregresse sulla dinamica recente ed attuale degli alvei (si veda in proposito pe l l e g r i n i et al., 2008; ri n a l d i et al. 2008; su r i a n et al. 2008a; 2008b). per alcune caratteristiche degli alvei, in particolar modo per la larghezza, si dispone infatti di accurate ricostruzioni temporali, mentre rimangono più problematiche le ricostruzioni delle variazioni altimetriche per vari corsi d'acqua. ad esempio per quanto riguarda le variazioni di larghezza, non solo è ben documentata la fase principale di restringimento generalmente verificatasi tra gli anni '50 e gli anni '80-'90 del xx sec., ma anche le variazioni avvenute nel xix sec., nella prima metà del xx sec., e quelle più recenti. per gli ultimi 15-20 anni, come già anticipato, si è riscontrata in vari casi una tendenza all'allargamento dell'alveo, anche se non mancano tratti fluviali che cont in uan o in un processo di rest ringiment o (surian et al., 2008a). anche sui fattori che hanno indotto l'instabilità degli alvei il grado delle conoscenze è progredito in modo significativo, sia attraverso l'acquisizione di maggiori informazioni sugli interventi antropici in alveo e a scala di bacino, che attraverso analisi delle serie idrologiche (precipitazioni e portate). le conoscenze acquisite nel corso del progetto permetteranno quindi di affinare i modelli evolutivi attualmente esistenti (surian & rinaldi, 2003; 2004). sulla base del contesto nazionale ed internazionale della ricerca (a questo ultimo si è fatto cenno nel capit olo in t ro dut t iv o, ma s i v eda an ch e j a m e s & ma r c u s, 2006; br a s i n g t o n & ri c h a r d s, 2007; ha b e rsack et al., 2008) gli aspetti sui quali dovrebbe mirare la ricerca nei prossimi anni sono, a nostro avviso, quelli qui di seguito elencati. 1. tendenze evolutive in atto. considerando che la fase principale di aggiustamento, ossia l'intenso restringimento ed incisione verificatisi generalmente fino agli anni '80-'90 del xx sec., è ormai generalmente esaurita, ed anche abbastanza bene documentata, è importante concentrare l'attenzione sull'ultima fase di aggiustamento in atto da alcuni anni. le variazioni più recenti, molto probabilmente indotte da una forte riduzione dell'attività di prelievo di sedimenti in alveo, sono state analoghe in vari casi (allargamento e sedimentazione) ma è plausibile aspettarsi dinamiche d'alveo differenti in relazione anche ad altre condizioni esistenti a scala di bacino e lungo i corsi d'acqua stessi (ad esempio la presenza o meno di dighe), nonché alla sequenza ed intensità degli eventi di piena. 2. l'impiego del telerilevamento e di tecniche quali lidar e gps. per la ricostruzione delle tendenze evolutive più recenti e per il monitoraggio della dinamica in atto gli strumenti più idonei appaiono le fotografie aeree a grande scala, tecniche topografiche quali lidar, gps e fotogrammetria, oltre al rilevamento geomorfologico in campo (per quest'ultimo aspetto si rimanda al punto successivo). mentre l'impiego delle fotografie aeree è consolidato e consente un'accurata quantificazione delle caratteristiche planimetriche dell'alveo, lidar, gps e fotogrammetria sono state impiegate nello studio della dinamica fluviale solo recentemente (la n e et al., 2003; hi c k s e t al., 2008; lollino et al., 2008; rumsby, et al., 2008), ma hanno notevoli potenzialità. la possibilità di acquisire modelli digitali del terreno (dem), non trascurando i problemi associati alla presenza di aree emerse e sommerse, rappresenta senz'altro un grande salto di qualità nella valutazione dei processi di erosione/sedimentazione in alveo, ma anche per la costruzione di bilanci di sedimenti (fu l l e r et al. , 2003; br a s i n g t o n et al., 2003) e quindi per una migliore comprensione dei processi in atto. 3. il rilevamento geomorfologico dell'alveo. il rilevamento sul terreno, con l'impiego di schede specifiche (rinaldi, 2008), è un aspetto cruciale soprattutto per la valutazione delle variazioni altimetriche. il metodo è essenziale per la ricostruzione delle variazioni passate, infatti raramente si dispone di una documentazione completa di rilievi topografici, ma anche per la valutazione delle tendenze attuali. riguardo quest'ultimo aspetto, il rilevamento geomorfologico può affiancarsi ai rilievi topografici (ad esempio gps e lidar) oppure sostituirsi completamente a questi quando non sussistano le condizioni per poterli realizzare. 4. i modelli e la previsione dell'evoluzione futura degli alvei. le conoscenze acquisite sull'evoluzione passata ed in atto degli alvei fluviali e sulle relative cause consentiranno di mettere a punto dei modelli che dovranno essere impiegati per prevedere l'evoluzione futura degli alvei. un primo passo sarà la messa a punto di modelli concettuali di evoluzione degli alvei, in grado di descrivere, seppure in termini di tendenza e quindi non quantitativi, la dinamica degli alvei italiani. tali modelli andrebbero quindi supportati da una quantificazione delle principali variabili che possono avere influenza sulla dinamica fluviale (ad esempio pendenza del fondo, dimensioni granulometriche, ecc.), in modo da individuare risposte morfologiche diverse al variare di tali parametri. oltre ai modelli concettuali, sarà importante l'utilizzo di modelli matematici, almeno per casi rappresentativi, per consentire una migliore comprensione dei rapporti tra cause ed effetti e per simulare possibili scenari di evoluzione. ad esempio i modelli cellulari, recentemente piuttosto diffusi nell'ambito della geomorfologia fluviale (nicholas et al., 2006; coulthard et al., 2007) potrebbero essere adatti a morfologie fluviali complesse (b r a i d e d o transizionali) come quelle presenti in molti corsi d'acqua italiani. in ogni caso le previsioni dovranno tener conto di possibili scenari di impatto antropico e di condizioni climatiche. 5. applicazione delle conoscenze alla gestione e riqualificazione dei corsi d'acqua. nell'ottica di una gestione sostenibile dei corsi d'acqua e tenendo come ri fer ime n t o i co n t en u t i del la d ir et t iv a qu a dr o 2000/60, è evidente l'importanza di trasferire le conoscenze acquisite con queste ricerche nella 236 n. surian & m. rinaldi gestione e riqualificazione degli alvei. da una parte è importante che la gestione/riqualificazione si basi sulle tendenze evolutive dei corsi d'acqua (si veda ad esempio do w n s & gr e g o r y, 2004), dall'altra è essenziale che la gestione dei sedimenti assuma un ruolo più rilevante nei corsi d'acqua italiani considerando che l'alterazione nel regime del trasporto solido è stata una causa fondamentale delle modificazioni recenti ed in atto negli alvei fluviali. una gestione efficace e sostenibile dei sedimenti può realizzarsi anche attraverso l'adozione di nuovi approcci, come la definizione di una fascia di mobilità fluviale (piegay et al., 2005; ri n a l d i, 2006; ha b e r s a c k & pi e g a y, 2008). 4. conclusioni la presente analisi della ricerca sulla dinamica recente ed attuale degli alvei fluviali in italia suggerisce le seguenti considerazioni conclusive. 1. la dinamica recente ed attuale degli alvei ha destato l'interesse di un certo numero di ricercatori sin a partire dagli anni '60 del secolo scorso, in relazione al fatto che gli alvei italiani hanno subito delle notevoli modificazioni morfologiche con rilevanti implicazioni da un punto di vista applicativo. 2. nel corso degli anni si è giunti ad una buona conoscenza delle variazioni morfologiche che hanno interessato gli alvei italiani e delle relative cause, anche grazie ad approcci sempre più quantitativi. 3. i recenti sviluppi della ricerca suggeriscono che in futuro si dovrebbe puntare sull'impiego di tecniche quali gps, lidar, e fotogrammetria digitale per il monitoraggio, sulla modellazione (da quella concettuale a quella numerica), ma anche sul rilevamento geomorfologico dell'alveo che, per quanto problematico, e talvolta non risolutivo, deve comunque mantenere un ruolo di riferimento. infine la ricerca dovrà trovare sempre maggiore applicazione nell'ambito della gestione e della riqualificazione dei corsi d'acqua. ringraziamenti ricerca realizzata nell'ambito del progetto prin 2005 “dinamica recente ed attuale di alvei fluviali in italia centro-settentrionale: tendenze evolutive, cause ed implicazioni applicative” (coordinatore nazionale: n. surian). si ringraziano luisa pellegrini e ornella turitto per i loro commenti e suggerimenti che hanno permesso di migliorare la stesura definitiva di questo articolo. bibliografia adamoli l. & bertini t. 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(2000) medium and short-term channel planform changes on the rivers tay and tummel, scotland geomorphology, 34, pp. 195208. xu jiongxin (1997) evolution of mid-channel bars in a braided river and complex response to reservoir co n st r u ct io n : a n e xamp le fr o m t h e mi dd le hanjiang river, china earth surf. process. and landforms, 22, pp. 953-965. 240 ms. ricevuto il 1° febbraio 2008 testo definitivo ricevuto il 12 maggio 2008 ms. received: february 1, 2008 final text received: may 12, 2008 n. surian & m. rinaldi base plio-quaternary geological evolution of the high salto river valley (central italy): the marano de’ marsi unit edi chiarini1, marco giardini2, massimo mattei3, felicia papasodaro1, massimiliano porreca3 & laura sadori2 1dipartimento difesa del suolo – geological survey of italy, ispra, roma edi.chiarini@isprambiente.it 2dipartimento di biologia vegetale, sapienza university of rome 3dipartimento di scienze geologiche, roma tre university abstract: chiarini e. et al., plio-quaternary geological evolution of the high salto river valley (central italy): the marano de’ marsi unit. (it issn 0394-3356, 2009). this paper summarizes the results of multidisciplinary researches carried out in a wide span of time on the earliest continental deposits of the high salto river valley. the study led us to characterize sedimentary environments, to analyze their relationships and to propose a chronological attribution. facies are referable to a complex depositional system consisting of a gilbert-type lacustrine delta and of slope-type partly interfingered fan deltas coming from the eastern border of the basin. the geological data collected allowed us to refer the succession to a single sedimentary cycle; in marano de’ marsi area the paleodrainage and progradation directions were also recognized. to better constrain the chronological, paleoclimatic and paleoenvironmental context, detailed investigations have been conducted on pelitic facies of the deltaic-lacustrine system in two sampling sites (an artificial outcrop at marano de’ marsi village and a borehole near borgorose village). paleomagnetic analyses show that marano de’ marsi and borgorose successions have a normal polarity and generally low magnetic susceptibility values. pollen diagrams from both sites mainly record a mid to high elevation forest pollen rain. the existence of trees from different vegetation belts suggests the presence of a well developed mountain system in the surroundings. in the case of marano de’ marsi section, these vegetation phases alternate with sudden, strong and short spreads of temperate and subtropical taxa. these alternations suggest that important climate changes occurred, with cyclical forest variations typical of glacial / interglacial periods of pliocene and early pleistocene. pollen and paleomagnetic data led us to refer both records to the olduvai subchron, at the end of the pliocene; nevertheless, the possibility that the records deposited during the gauss chron cannot be, definitely, excluded. field geological data and magnetic fabric results suggest that the marano de’ marsi unit sedimentation took place in a basin developed under extensional tectonic regime. riassunto: chiarini e. et al., evoluzione geologica plio-quaternaria dell’alta valle del fiume salto: l’unità di marano de’ marsi. (it issn 0394-3356, 2009). il lavoro sintetizza i risultati di studi multidisciplinari condotti, nel corso di numerosi anni, sui depositi continentali più antichi dell’alta valle del fiume salto. attraverso tali studi è stato possibile caratterizzare gli ambienti di sedimentazione e le relazioni fra essi esistenti, oltre che fornire indicazioni cronologiche più precise. il rilevamento dettagliato di terreno ha consentito il riconoscimento delle facies che compongono tali depositi e la ricostruzione della loro distribuzione, permettendone l’attribuzione prevalentemente ad un delta lacustre di tipo gilbert e subordinatamente a delta-conoidi, originati da canaloni o da corsi d’acqua a basso grado di maturità. i dati di terreno raccolti in questo studio fanno ritenere che l’unità di marano de’ marsi rappresenti il risultato di un unico ciclo sedimentario, sebbene molto articolato perché attribuibile ad un sistema deposizionale complesso. nell’area di marano, l’esame dei foreset e delle altre strutture sedimentarie riconosciute ha fornito dati importanti per la ricostruzione del verso del drenaggio e della progradazione del delta. per precisare il quadro paleoclimatico, paleoambientale e cronologico, sono state condotte indagini paleomagnetiche e palinologiche di dettaglio su due successioni affioranti nelle località di marano de’ marsi e borgorose, in corrispondenza delle facies pelitiche del sistema deltizio/lacustre. le analisi paleomagnetiche indicano che entrambe le successioni studiate hanno polarità magnetica normale e valori di suscettività magnetica relativamente bassi, in accordo con la composizione dei sedimenti essenzialmente carbonatica. i record pollinici registrano prevalentemente fasi forestali con elementi di media ed alta quota. la presenza di alberi tipici di diverse fasce vegetazionali suggerisce la presenza di un sistema montano ben sviluppato nelle vicinanze. a marano de’ marsi queste fasi vegetazionali si alternano con espansioni improvvise, consistenti e di scarsa durata di alberi temperati e subtropicali. queste alternanze inducono a pensare che si siano verificati importanti cambiamenti climatici nel periodo considerato, con variazioni forestali cicliche, tipiche dei periodi glaciali/ interglaciali che vanno dal pliocene medio fin quasi alla fine del pleistocene inferiore. l’interpretazione congiunta dei risultati paleomagnetici e palinologici suggerisce l’attribuzione di entrambe le successioni al pliocene. pur non potendo del tutto escludere l’attribuzione al crono gauss (pliocene medio), il confronto con lavori palinologici ottenuti da sedimenti continentali e marini italiani, insieme a considerazioni di geologia regionale, fanno propendere per un’attribuzione di entrambe le successioni al subcrono olduvai (pliocene superiore). i dati geologici e i risultati di anisotropia della suscettività magnetica suggeriscono che la sedimentazione dell’unità di marano de’ marsi sia avvenuta in un bacino sviluppatosi sotto un regime tettonico di tipo estensionale. keywords: deltaic-lacustrine facies; pollen; plant macrofossils; magnetostratigraphy; pliocene; salto valley; central apennines. parole chiave: facies deltizie-lacustri; polline, macrofossili vegetali; magnetostratigrafia; pliocene; valle del salto; appennino centrale. il quaternario italian journal of quaternary sciences 22(2), 2009 325-344 326 e. chiarini et al. 1. introduction a complex interaction among tectonic uplift, normal fault activity, erosional events and depositional episodes characterizes the plio-pleistocene evolution of the central apennines. the main features of the most recent phases of this tectono-sedimentary evolution are generally well known. in the contrast, the definition of the earlier phases needs to be improved, although a general correlation of the sedimentary infill of the main intermountain basins had already suggested (bosi & messina, 1991; bosi et al., 2003). to this aim stratigraphic and sedimentological studies of continental deposits can be usefully integrated with analyses of erosional paleosurfaces and multidisciplinary research. in the high valley of the salto river, near the latium and abruzzi regions boundary, wide outcrops of continental deposits testify the early steps of the plioquaternary evolution of the area; the sediments have been deposited on the margin of or within a lake no more recognizable in the present-day landscape. these deposits have been studied in the framework of the field survey carried out for the sheet n° 367 of the new geological map of italy at a scale 1:50.000 (servizio geologico d’italia, 2005) and of the same sheet of the geomorphological map ( s e r v i z i o geologico d’italia, 2008). the study has been integrated with paleomagnetic and paleobotanic investigations to better constrain the age of the deposits and to define the paleoclimatic and paleoenvironmental context. in this paper we report the main results of these studies and some considerations on the geological and tectonic history of the sedimentary basin. 2. geological and structural setting the studied area is located in the high salto river valley (fig. 1), between the carseolani mts. to the sw, and the mt. velino chain to the ne. these mountain ranges are mainly formed by lower cretaceousmiocene limestones and dolostones, referable to the latium-abruzzi carbonatic platform paleogeographic domain (compagnoni et al., 2005). the siliciclastic deposits overlying carbonatic units, related to the evolution of the apennines tortonian-messinian foredeep basin (bellotti, 1992; cipollari & cosentino, 1995), crop out south-eastward (palentini planes), northward (malito valley) and north-westward (salto lake), but are lacking in this valley sector. along the valley axis and in the nearby area (fig. 2), continental deposits of gravitative, alluvial, and fig. 1 shaded relief of the apennine sector between the fucino and rieti intermontane basins and location of the study area. modello ombreggiato del settore appenninico compreso fra la piana del fucino e la piana di rieti ed ubicazione dell’area in studio. 327plio-quaternary evolution of the high salto river valley ... lacustrine origin occur. they are organized in several depositional cycles and are separated by stratigraphic unconformities related to major erosional events (chiarini et al., 2007; 2008). the oldest continental deposits, described in this study, crop out between marano de’ marsi (aq) and borgorose (ri) villages. in previous studies, they have been attributed to different sedimentary events. in the geological sheet n° 367 “tagliacozzo” (s e r v i z i o geologico d’italia, 2005), authors described a first alluvial unit and a following succession recording a progressive evolution from an alluvial to a lacustrine environment, unconformably covered with breccias cropping out in the spedino and borgorose areas. all these units have been doubtingly related to the pliocene. busino (1990) and federici (1990) recognized two main depositional events. the first event, messinian or pliocene in age, produced lacustrine clayey sediments (fosso s. martino formation); the second one consists of two formations (torano and marano de’ marsi formations), which correlated each other and referable to the pliocene, composed of several members. bo s i & federici (1993) correlated part of these deposits to the first continental cycle of the fucino basin (s. pelino succession of bertini & bosi, 1976 and aielli complex of bosi et al., 1995), ascribed to pliocene. for the general shortage of dating materials, these chronological data are essentially provided on the basis of morphostratigraphic observations and analogies with other successions of central apennines. the salto river valley lies just to the west of the apennines watershed, between the fucino and the rieti basins, and follows regional tectonic lineaments, corresponding to a nw-se fault system with a multiphase tectonic activity (nijman, 1970; bosi et al., 1994; bigi & costa pisani, 2003). during plio-pleistocene a segment of the fault system (salto valley fault), with a main normal fault activity, controlled the location and the evolution of a continental basin (galadini et al. 2000; 2003), in the intermediate segment of the salto valley, where the artificial homonymous lake is presently located (fig. 1). this basin has been mostly obliterated by subsequent tectonic and morphogenetic events. in the high valley the tectonic structure shifts eastward. indeed a morphologically evident fault along the base of duchessa mountain range (mt. velino chain, see fig. 1) shows an en échelon geometry (galadini & messina, 2001; 2004; morewood & roberts, 2001) with the salto valley fault above mentioned. an important activity phase of duchessa mts. fault has caused the individualization and the evolution of the small corvaro intermountain basin (fig. 2), since the early pleistocene according to bosi & federici (1993). these tectonic events induced a dramatic change in the paleogeography of the area. they made it difficult to recognize the sedimentary basin of the oldest continental deposits and the faults responsible for its structuring. nevertheless, available data make it possible to assume that: 1) sedimentary events considered in this paper took place inside an extensional basin; 2) the tectonic structures that controlled the evolution of this ancient basin could be the same as that responsible for the corvaro basin setting. indeed, the tilting of the succession, generally 10° to 30° toward north-east, suggests the localization of the main fault on the eastern basin flank. moreover, the several tectonic elements affecting the studied sedimentary succession are related to extensional tectonic regime, although referable to different phases. nw-se and nnw-sse trending faults confine deposits in a narrow and elongated belt inside the carbonatic bedrock (fig. 2). along the western margin, the contact of the deposits with the meso-cenozoic limestones consists of rectilinear and high-angle faults, segmented by minor transversal faults. along the eastern border, the boundary is generally tectonic as well; only locally, deposits unconformably rest on the calcareous bedrock. these faults could belong to the duchessa mts. fault system, even if they show a moderate morphological evidence (fig. 2). e-w trending minor faults also displace the marano de’ marsi unit. at present, a wide and flat erosional surface (colle vena francesca paleosurface) almost obliterates the offsetting of the above cited faults; it has been recognized at about 950 m a.s.l. on both the marine carbonatic substratum and the deposits examined in the present work (fig. 2). in a preliminary study, chiarini et al. (1997) have shown that the colle vena francesca paleosurface had formed before the corvaro depression setting: in fact it shows considerable displacement across the duchessa mts. fault. the paleosurface results from the complex interaction of depositional events, erosional phenomena and activity phases of faults; centamore & nisio (2002a; b) have related it to the fontanelle surface located in the mid salto valley. therefore, the wide extension of the colle vena francesca paleosurface would highlight its importance in the stratigraphic frame of the area and testifies an important change in the basin subsidence trend. 3. stratigraphic and sedimentological features the succession, named marano de’ marsi unit, crops out discontinuously along the left flank of the salto valley, close to marano de’ marsi village, at altitudes comprised between 959 m and 710 m a.s.l.; it also crops out between torano and borgorose, from 670 m to 951 m a.s.l. (fig. 2). the maximum thickness preserved from erosion is of about one hundred meters. it is composed of lacustrine marls, claystones, siltstones and arenites and by arenites, gravels and conglomerates of fluvial, deltaic and slope environment, which overlay the carbonatic substratum. this continental succession ends with the above mentioned colle vena francesca erosional surface (fig. 2); it is unconformably covered with the alluvial fan systems of teveruara valleys in the torano area and of valle amara in the borgorose area. deposits of younger cycles sedimented after the infilling and dissection of the corvaro basin and have been referred to the glacial phases of upper pleistocene (servizio geologico d’italia, 2008). to collect stratigraphic and sedimentological data, a geological survey was performed at 1:10.000 scale, supported with photo-geological analysis, observations of natural and artificial outcrop sections and of 328 e. chiarini et al. 329 laboratory samples. a great facies variability was observed. the lack of important erosional discontinuities and the interbedding of lithofacies allow us to refer this succession to a single sedimentary cycle. depositional structures described in this paper were mainly referred to a lacustrine gilbert-type delta for the occurrence of the typical three stratigraphic components (bottomset, foreset and topset; fig. 3); secondly they were connected to slopetype fan-deltas with a high gradient. sharp facies variations frequently mark the emergence of faults belonging to the main apennine system or transversal tectonic elements as observed west of marano de’ marsi and near torano. the recognized facies can be grouped into three main facies associations (a, b, c; fig. 2) on the basis of their meaning, relationships and spatial distribution. facies association a this association groups prevailingly ruditic facies referred to the lacustrine gilbert-type delta, because in many cases their differentiation is made difficult by the bad outcropping conditions. conglomerates with carbonatic pebbles, subangular or subrounded, sub-centimeters to centimeters in size widely crop out in the area; the sediments are clast supported, with a pebbly to muddy matrix, cross-bedded to plane-bedded foresets and moderately sorted beds and laminations; massive coarse-grained sandy beds and decimetric to metric pelitic intervals are frequently present. pedorelicts and sequences referable to paleo-channel filling have also been recognized. these facies occur at mt. pago osco and near marano de’ marsi and torano villages (figs. 2, 4 and 5). between torano and colle scarciofano (fig. 5), in the upper portion of the outcropping succession a lenticular body of well stratified sandstones, several meters thick, occurs; it is characterized by parallel and cross bedded laminations, well cemented strata, oxides rich levels, and thin coarse grained horizons from sandfig. 3 longitudinal interpretative cross section of marano de’ marsi area. 1) recent alluvial and colluvial deposits (upper pleistocene olocene); 2) marano de’ marsi unit sub-rounded to rounded coarse grained conglomerates of gilbert-type delta topsets; 3) marano de’ marsi unit subangular to subrounded fine grained conglomerates with arenitic levels (a) of gilbert-type delta foresets; 4) marano de’ marsi unit pelitic and ruditic deposits of gilbert-type delta bottomsets; 5) carbonatic bedrock; 6) boundary: (a) etheropic, (b) erosional of low order, (c) erosional of high order ; 7) fault. sezione interpretativa longitudinale dell’area di marano de’ marsi. 1) depositi alluvionali e colluviali recenti (pleistocene superioreolocene); 2) unità di marano de’ marsi – conglomerati con clasti grossolani, da subarrotondati ad arrotondati, dei topset del delta gilbert; 3) unità di marano de’ marsi – conglomerati a granulometria fine, con clasti da subangolari a subarrotondati, con livelli arenitici (a) dei foreset del delta gilbert; 4) unità di marano de’ marsi – depositi pelitici e ruditici dei bottomset del delta gilbert; 5) substrato carbonatico; 6) contatto: (a) eteropico, (b) erosionale di basso ordine, (c) erosionale di alto ordine; 7) faglia. plio-quaternary evolution of the high salto river valley ... fig. 2 geological sketch map of the study area. 1) quaternary deposits; 2) marano de’ marsi unit (middle?-upper pliocene) alluvialdeltaic deposits of facies association a: fine to coarse grained conglomerates and gravels of gilbert-type delta topsets (a) and foresets with arenitic levels (b); 3) marano de’ marsi unit lacustrine-deltaic deposits of facies association b: marls, marly claystones, siltstones and conglomerates of gilbert type delta bottomsets and frankly lacustrine environment; 4) marano de’ marsi unit slope-type fan deltas deposits of facies association c: breccias with laminated yellow siltstones, calcarenites, marls and claystones; 5) fault; 6) inferred or buried fault; 7) bedding strike and dip; 8) colle vena francesca paleosurface; 9) marano de’ marsi (tore) section; 10) borgorose (fornace dei laterizi) borehole. carta geologica schematica dell’area in studio. 1) depositi quaternari; 2) unità di marano de’ marsi (pliocene medio?superiore) depositi fluvio-deltaici dell’associazione di facies a: ghiaie e conglomerati da fini a grossolani dei topset (a) e foreset con livelli arenitici (b) del delta gilbert; 3) unità di marano de’ marsi – depositi deltizi e lacustri dell’associazione di facies b: marne, argilliti marnose, siltiti e conglomerati dei bottomset del delta gilbert e di ambiente francamente lacustre; 4) unità di marano de’ marsi – depositi di delta conoide dell’associazione di facies c: brecce con siltiti gialle, calcareniti, marne e argilliti laminate; 5) faglia; 6) faglia incerta o sepolta; 7) giacitura degli strati; 8) paleosuperficie di colle vena francesca; 9) sezione di marano de’ marsi; 10) sondaggio di borgorose (fornace dei laterizi). þ 330 stones to fine breccias. in these strata, small remnants of plants in a physiological position are often present. paleocurrents direction, evaluated using foresets geometry and clasts embrication, varies from nw to ne, suggesting a drainage from south to north. this facies have been referred to the frontal part of the gilbert-type delta. coarse grained conglomerates, moderately sorted, poorly stratified, with bedding thickness ranging from 0.5 m to 5 m crop out on top of succession; deposits are clast supported with a pebbly-sandy matrix and pebbles centimeters to pluricentimeters in size, from sub-rounded to rounded. between the ruditic beds decimetric intercalations of finer sediments are present; these consist of thin horizons of claystones and beds of oxides-rich yellow calcarenites, with parallel and cross lamination. the transition to the overlying ruditic beds is given by a decimetric level of fine grained breccias. moulds related to dry up cracks are noticeable between claystones and calcarenites. these deposits extensively crop out in the area between mt. s. angelo and colle scarciofano (figs. 2, 4 and 5) and are interpreted as topset of the gilbert-type delta system, referred to an alluvial or deltaic plain environment. gravel lithology of the facies association is exclusively carbonatic, whereas finer grain-size classes are also siliciclastic. facies association b this facies association is composed of prevailingly pelites, consisting of marls, carbonatic siltstones and silty claystones, with a grey to dark-grey color, massive, poorly stratified to thinly laminated. whitish, light, limy-clayey horizons, rich of fresh water diatoms, are also present. pelitic deposits include conglomerate bodies; in this context the transition from pelitic lithologies to the overlying ruditic beds is sharp and consists of an etherometric gravelly horizon with muddy matrix and thin levels of silty claystones with shell fragments. these deposits crop out northwest of marano de’ marsi village, in valle di tesio locality; they are also present in a narrow belt between the rosa mt. slope and the laduschio mt.-castelvecchio mt. relief, and then in a wide outcrop in the borgorose area. at the base of the saticone mt. slope, the facies association includes intraformational slumps consisting of a close alternation of carbonatic siltstones and clayey marls, deformed by mesofolds and joints. ruditic facies also include carbonatic metric boulders and chaotic facies, as visible at valle di tesio; these elements probably indicate a tectonic instability along the depositional slope. the observed facies have been ascribed either to a frankly lacustrine environment or to a distal portion of the deltaic system (bottomset). fresh water ostracods referable to the genus fig. 4 upper portion of facies association a exposed at mt. saticone near marano de’ marsi. a) outcrop of cross-bedded fine grained conglomerates; b) detail of moderately sorted cross-bedded foresets; c) sedimentological log. 1) cross-bedded fine grained conglomerates of delta-front facies (foresets); 2: poorly stratified, well rounded coarse grained conglomerates of alluvial-deltaic plain facies (topsets); c: clay; s: silt; sa: sand; g: fine gravel; pe: pebble; co: cobble. porzione superiore dell’associazione di facies a esposta al mt. saticone, nei pressi di marano de’ marsi. a) affioramento di conglomerati a granulometria fine e a stratificazione incrociata; b) dettaglio degli orizzonti a stratificazione incrociata moderatamente classati; c) log sedimentologico. 1) conglomerati a granulometria fine e a stratificazione incrociata del fronte deltizio (foreset); 2) conglomerati a clasti grossolani e ben arrotondati, scarsamente stratificati, di piana alluvionale e deltizia (topset); c: argilla; s: silt; sa: sabbia; g: ghiaia fine; pe: ghiaia media; co: ghiaia grossolana. e. chiarini et al. candona s.p. and erpetocypris s.p., gasteropoda fragments and characee thalluses (pampaloni l. & pichezzi r.m., servizio geologico d’italia, personal communication), are observed inside the pelitic sediments. facies association c this facies association consists of breccias with metric and plurimetric bedding or poorly defined strata, containing sub-angular to sub-rounded carbonatic clasts ranging in size from 0.5 to 10 cm, within a sandypebbly matrix. breccias are poorly organized, clast supported or, less frequently, matrix supported; inverse gradations also occur. thin normal graded interbeddings of small sized breccias, laminated yellow siltstones, calcarenites, marls and claystones are present. in some cases these facies rest on top of lacustrine claystones via clastic horizons rich of shell fragments. t h e a s s o c i a t i o n m i g h t i n c l u d e r u d i t i c d e p o s i t s r e f e r a b l e t o b o t t o m s e t s o f t h e m a i n gilbert-type delta, for the etheropic relationships between each other and the close facies similarity. it crops out in the area comprised between torano and borgorose villages, where it is locally covered with ruditic facies of the association a. according to sedimentary structures, ascribed either to a mass transport or, less frequently, to tractive flows, and because of the general lack of a clear foreset facies, this association has been referred to slope-type fan deltas which was originated from stream channels of a low order with a very small and steep catchment area. the facies distribution is consistent with a sediment supply from the eastern border of the basin. 4. the studied stratigraphic logs in order to better define the age of the marano unit and to have indications on the paleoclimate that conditioned the sedimentary events, paleomagnetic and paleobotanic investigations have been carried out on fine sediments of two successions (sadori, 2005). a first one, called marano de’ marsi section, is constituted by deposits belonging to the facies association b and referred to a distal portion of the gilbert delta. a second succession has been studied through a 24 m long core, drilled close to borgorose village and therefore called borgorose core. it is characterized by clays and silts referred to a frankly lacustrine environment. 4.1 marano de’ marsi section this section is located in a marginal position of the salto valley, at an elevation of 720 m a.s.l. (fig. 2). the vertically cut surface is about 11 m high. deposits are rather homogeneous and for about 10 meters from the bottom lacking in significant discon331 fig. 5 upper portion of facies association a exposed at colle scarciofano. a) outcrop of rounded coarse grained conglomerates (topsets). b) sedimentological log. 1) stratified sandstones with paralleland cross-bedded laminations of delta-front facies (foresets); 2) cross-bedded fine to coarse grained conglomerates of delta-front facies (foresets); 3) claystones, oxides-rich yellow calcarenites and fine grained breccias; 4) poorly stratified, sub-rounded to rounded, coarse grained conglomerates of alluvial-deltaic plain facies (topsets); c: clay; s: silt; sa: sand; g: fine gravel; pe: pebble; co: cobble. porzione superiore dell’associazione di facies a esposta al colle scarciofano, nei pressi di borgorose. a) affioramento di conglomerati a granulometria grossolana (topset). b) log sedimentologico. 1) arenarie stratificate con laminazioni parallele e incrociate; 2) conglomerati a granulometria da fine a grossolana, a stratificazione incrociata del fronte del delta; 3) argilliti, calcareniti gialle, ricche di ossidi e laminate, e brecce a granulometria fine in intercalazioni decimetriche; 4) conglomerati a clasti grossolani da subarrotondati ad arrotondati, mal stratificati, di piana alluvionale e deltizia (topset) c: argilla; s: silt; sa: sabbia; g: ghiaia fine; pe: ghiaia media; co: ghiaia grossolana. plio-quaternary evolution of the high salto river valley ... formities; they consist of pale to dark grey silty marls and marly claystones and siltstones, with massive to thinly laminated beds and horizons (fig. 6a). sandy oxidized laminae, a few millimetres thick, cross-laminated levels and muddy pebbles, also occur. at the top, a weakly north verging cut surface marks the transition to an intraformational slump of laminated siltstones and marly claystones, including microfolds and fractures. at the base of the section, whitish horizons of particularly light clayey marls with fresh water diatom remnants, crop out. these sediments have been subject of two specific samplings, i.e. paleomagnetic and pollen and macrofossil plant sampling. 4.1.1 paleomagnetic analyses paleomagnetic sampling and laboratory methods in the marano de’ marsi section, we sampled 154, 2.5 cm in diameter, cores (fig. 6). cores have been drilled with a asc-280 gasoline-powered drill and oriented in situ with a magnetic compass. the average stratigraphic distance between the sampled cores was 10 cm, along the whole outcropping section. the uppermost part of the section, below the slumping, was sampled more in detail in order to study the timing relationships between slump and the acquisition of remanent magnetization. most of the paleomagnetic analyses were carried out at the paleomagnetic laboratory of the department of geological sciences of roma tre university, some of them at eth paleomagnetic laboratory of natural magnetism in zurich. in particular, low-field magnetic susceptibility (km) and its anisotropy were measured in the paleomagnetic laboratory of roma tre university using an agico kly-3 kappabridge. successively, the natural magnetic remanence (nrm) was measured using a jr6 spinner magnetometer and a 2g-enterprise squid cryogenic magnetometer at roma tre university and eth zurich, respectively. magnetic susceptibility analyses low-field magnetic susceptibility (km) was measured along the whole section in 10 cm 3 volume specimens. km values include the contribution of all magnetic minerals (diamagnetic, paramagnetic and ferromagnetic grains) present in the sediment in proportion to their susceptibility, abundance and grain size. generally, if a sediment contains paramagnetic minerals as common constituents, susceptibility values are not higher than 100-200 x 10-6 si. magnetic susceptibility analysis has been increasingly used in the last few years as a valid proxy for magnetic minerals concentration (verosub & roberts, 1995; dekkers, 1997) and then can be useful to define the presence of climatically induced cyclicity in sedimentary records (for example alternation of carbonates and clays) (dekkers, 1997). in fact, the susceptibility fluctuations is used as a sensitive indicator of temporal variations in terrigenous input which are likely caused in changes of lake/sea level and 332 fig. 6 stratigraphic log of marano de’ marsi section (a) related magnetic susceptibility (b) and natural remanent magnetization (c) profiles. colonna stratigrafica schematica della sezione di marano de’ marsi (a), profili della suscettività magnetica (b) e della magnetizzazione naturale rimanente (c). e. chiarini et al. 333plio-quaternary evolution of the high salto river valley ... erosion of the continental subaereal landscape (rosenbaum et al., 1996). in the marano de’ marsi lacustrine section the magnetic susceptibility values are low in average and range between 14 and 164 x 10-6 si (fig. 6b). in general, they display a small variation in that interval, reflecting stable and constant input of diamagnetic (mainly calcite) and paramagnetic (clay minerals) grains from substrate during the deposition. moreover, this excludes the presence of any volcaniclastic contamination into the paleolake, such as pyroclastic fall products characterized by high content of ferromagnetic grains. volcaniclastic deposits are typical in middle pleistocene lacustrine intermountain basins in central and southern italy (cavinato et al., 1994). in detail, it is possible to see a weak increase in the values from the bottom to the top, in particular from 50 to 600 cm, with values from 14 to 70 x 10-6. this part is also characterized by a weak ciclicity with a frequency of about 20-40 cm for each cycle (fig. 6b). it is likely that this high frequency reflects the alternance of light and brown layers which have relatively major and minor content in carbonate grains respectively (i.e. minor and major content in magnetic grains). higher values are measured between 600 and 780 cm with a maximum value in correspondence of 756 cm. the remnant upper part of the section shows a constant trend up to the contact with the slumping, which is characterized by higher values, about 80-100 x 10-6 si. natural remanent magnetization (nrm) analyses the intensity of the nrm is in the 1-20 x 10-3 a/m range, without any particular variation along the marano de’ marsi section (fig. 6c). the widespread occurrence of diamagnetic and subordinate paramagnetic minerals is also responsible for the relatively low nrm values. as already seen in the susceptibility profile, also nrm profile of fig. 6c shows a constant trend around a mean value of 8.8 x 10-3 a/m and characterized by a ciclicity with a frequency similar to that of susceptibility (see figs. 6b and 6c). moreover, relatively higher values are recorded in the central part of the section between 400 and 800 cm, whereas they are lower in the upper and lower part of it. thermal demagnetisation technique was applied for most of the specimens, whereas alternating field (af) technique was applied only for some representative specimens. in the first kind of measurements the samples were thermally demagnetised with temperature increments of 30 and 50ºc, up to 440-480ºc, whereas in the second treatment the samples were progressively demagnetised in an alternating field (af) up to 100 mt. both measurements revealed valuable, givfig. 7 calculated paleomagnetic declination (a), inclination (b), maximum angular deviation (c) and virtual geomagnetic pole (d) for marano de’ marsi section. variazione della declinazione magnetica (a), inclinazione magnetica (b), massima deviazione angolare (c) e del polo geomagnetico virtuale (d) ottenuto dai dati di declinazione, inclinazione e latitudine. ing the same results. demagnetization diagrams are analysed by principal component analysis (kirschvink, 1980), in order to determine the chrm (characteristic remanent magnetization) directions for each sample. the maximum angular deviation (mad) is generally less than 10°. samples yielding mad>15° were rejected for further analyses. all the characteristic components are plotted on equal area stereographic projection before (in situ) and after correction for bedding tilt (tilting value is 8° toward nne). some representative paleomagnetic data obtained by thermal and alternating field (af) demagnetisations have been shown in sadori et al. (2009). the declination and inclination of the characteristic component (chrm) are projected versus stratigraphic height after application of bedding correction as shown in figures 7a, b. it is evident as the declination of this component is constant in declination around n, whereas the inclination is always positive (i.e. normal polarity) with a mean value of 55°, in agreement with the expected geomagnetic field (gad) direction expected for this locality. the small scatter of data both in declination and inclination is interpreted as due to secular variations of the earth’s magnetic field. no magnetic reversals are present in the investigated section. magnetostratigraphy the declination and inclination obtained for the chrm of each sample were used to calculate the virtual geomagnetic pole (vgp) latitude, yielding a magnetic polarity sequence in the studied section (fig. 7d). positive vgp latitudes indicate normal polarity for the whole section. in the lower part of the section from 0 to 600 cm, the profile of figure 7d indicates a weak drift of calculated vgp from 70°n to 84°n. in the topmost part of the section (the last 15 cm), the data are not reliable because the clay samples are disturbed by the slumping emplacement. the overall magnetic polarity stratigraphy outlined for tore section is well within a normal polarity magnetozone (i.e. olduvai subchron or gauss chron of pliocene age). anisotropy of magnetic susceptibility analyses the measurement of the low-field ams represents a rapid and non destructive method to define the mineral fabric of rocks (e.g., hrouda, 1982). the magnetic fabric has proven to be closely related to the strain ellipsoid in weakly deformed or “undeformed” clay sediments both in compressional and extensional tectonic regimes, and, consequently, it constitutes a valid tool in defining the deformative pattern in weakly deformed fine-grained sedimentary sequences (borradaile & tarling, 1981; kissel et al., 1986; lee et al., 1990; sagnotti et al., 1994; mattei et al., 1999; cifelli et al., 2004). the ams is defined by a second rank symmetric tensor and is represented geometrically by an ellipsoid with principal axes kmax>kint>kmin. the shape of the ams ellipsoids and the degree of the anisotropy can be described by several parameters (see also jelinek, 1981; hrouda, 1982). the magnetic lineation and foliation (at the sample and site scales) are defined as the kmax and the plane normal to the kmin respectively. the ams at both the specimen and the site levels was evaluated using the jelinek statistics (jelinek, 1978). in the case of a sedimentary magnetic fabric, the magnetic foliation is parallel to the plane of sedimentation whereas the magnetic lineation is dispersed on the foliation plane and reflects the hydrodynamic conditions in the depositional basin. in the case of a magnetic fabric induced by tectonic processes, the maximum axis of susceptibility (kmax) is commonly aligned along the direction of maximum stretching in extensional environments (e.g. mattei et al., 1997; cifelli et al., 2004). in extensional environments, it is well documented that the ams of rocks can be imparted during the very early stages of deformation (e.g. cifelli et al., 2004). the ams results of tore section are grouped in seven sites, from the bottom to the top of the section. the degree of anisotropy is generally low, with values of p’ well below 1.10, and the fabric is either oblate or prolate as shown in figure 8 (p vs. t). the shapes of ams ellipsoid are also not well defined with exception of site vs04 (fig. 9), characterized by oblate ellipsoid. the other sites show low anisotropy degree and a large variability in the shape parameter t. a poor defined magnetic foliation has been measured in all the sites. a well defined magnetic lineation, ne-sw oriented, has been recognized in only one site (vs04) from the middle part of the section. in all the other sites the magnetic lineation is generally dispersed on the foliation plane (fig. 9). the overall ams results demonstrate that the investigated deposit is characterized by a magnetic fabric poorly defined because of the low content in 334 e. chiarini et al. fig. 8 anisotropy degree (p) versus shape parameter (t) of all the measured samples of marano de’ marsi section. note the scatter of the data and the low value of p values. grado di anisotropia (p) vs. fattore di forma (t) per tutti i campioni misurati. si noti il grado di anisotropia molto basso e l’alta dispersione dei dati, che testimoniano un fabric magnetico poco definito. 335plio-quaternary evolution of the high salto river valley ... magnetic grains. in fact, the lacustrine section is composed mostly by carbonatic marls which contain extremely few ferromagnetic or paramagnetic grains. the shape of ams ellipsoids is therefore mostly related to sedimentary processes, where the magnetic foliation tends to reflect the deposition plane whereas the scatter of the magnetic lineation is likely related to hydrodynamic conditions of the lake at the moment of deposition. only site vs04, which has the higher km values (i.e. major amount of magnetic grains), is characterized by a well defined magnetic fabric with a ne-sw oriented magnetic lineation. this seems to suggest a stretching direction oriented parallel to the lineation, i.e. nesw, which could be the main extensional direction that has overprinted partially the lacustrine succession during tectonic deformation. 4.1.2 plant microand macrofossils analyses for plant fossils, a continuous column was taken, sampling big blocks of sediment later on subsampled in laboratory every 10 cm for pollen analyses and inspected for macrofossil ones. plant macrofossils preliminary analyses have shown the presence of a number of arboreal taxa: levels with angiosperm fossils are more abundant than those with gymnosperm ones (fig. 10). the fossil compressions/impressions mainly consist of leaves, but also fruits/seeds, woods and cuticles were found. the still provisional fossil list comprehends many angiosperms such as acer cfr. monspessulanum, carpinus cfr. orientalis, engelhardia sp., fagus cfr. sylvatica, hedera sp., liquidambar sp., quercus sp., rosa sp., as well as abies sp. and pinus sp. both engelhardia and liquidambar genera are extinct in europe and have species living only in asia the first, and both in asia and northern/ central america the second. some fossil specimens are shown in figure 11. plant microfossils 61 sediment samples have been analysed every 20 cm (with sampling improving at 10 cm at key depths), but only 57 showed a sufficient pollen content to be plotted in the diagram. known weights (ca. 2 g) of dry sediment were processed in a sterile laboratory, using a standard procedure consisting in hcl (30%), hf (40%) and naoh (10%) chemical attacks to remove both the mineral fraction and the organic matter. lycopodium spore tablets (stockmarr, 1971) have been added to estimate the pollen concentration values. the palynomorphs identification was carried out with a transmitted light microscope at a minimum magnification of 400x. the level of pollen conservation is low, often very low. the grains appear generally to be corroded and crumpled, slowing and making the analysis difficult. the total pollen concentration varied from 1900 to 129,000 pollen grains/g, the arboreal pollen (ap) percentages mainly ranged between 96 and 100%. 56 pollen taxa (with 11 herbaceous taxa in all) were identified. the number of terrestrial spermatophytes pollen taxa per level is between 15 and 39. the highest amount of pollen taxa matches both very low pollen concentration values (3200 pollen grains/g) and the highest percentage values of nap (13%) at 9.80 m. the number of extinct arboreal pollen taxa is high (14). fern spores and algal remains were also identified during routine pollen analyses. synthetical pollen curves are presented in figure 10. the basic sum is composed by all terrestrial spermatophytes (trees, shrubs and herbs), so excluding water plants, ferns and algal remains. for details concerning the pollen identification criteria and definition of pollen types, as well as for a complete pollen diagram see sadori et al. (2009). among gymnosperms pinus haploxylon type (plus cathaya), pinus sylvestris type, cedrus, picea, abies, tsuga, and taxodium type are found with significant values. among angiosperms, herbs are quite absent. dominant angiosperm tree taxa are quercus, zelkova, ulmus, carya and pterocarya (the last two are no longer spontaneously growing in our continent). the presence fig. 9 equiareal projection of ams principal axes for each site. note the well defined magnetic fabric for site vs04. proiezione equiareale dei principali assi dell’ellissoide dell’ams. si noti come il fabric magnetico sia ben definito nel sito vs04. 336 e. chiarini et al. f ig . 1 0 m a ra n o d e ’ m a rs i( r ie ti , c e n tr a li ta ly ). p o lle n d ia g ra m (s e le c te d ta xa a n d g ro u p s) . p o lle n g ro u p s: su b tr o p ic a lh u m id fo re st (t ax o d iu m ty p e , e n g e lh ar d ia , n ys sa , c fr . r h o ip te le a) ; te m p e ra te b ro a d le a ve d d e c id u o u s fo re st (c ar p in u s b e tu lu s, c ar ya , c as ta n e a, c e lt is , c o ry lu s, h am am e lid ac e ae u n d iff ., ju g la n s, ju g la n d ac e ae u n d iff ., l iq u id am b ar , p te ro c ar ya , q u e rc u s ro b u r ty p e , q u e rc u s c e rr is ty p e , t ili a, u lm u s, z e lk o va ); m id to h ig h e le va ti o n fo re st (a b ie s, c e d ru s, p ic e a, t su g a, b e tu la , f ag u s) ; sc le ro p h yl lo u s fo re st (q u e rc u s ile x ty p e , o le a) ; xe ri c e le m e n ts (h e rb s a n d e p h e d ra ). m ar an o d e ’ m ar si (r ie ti , it al ia c e n tr al e ). d ia g ra m m a p o lli n ic o (t a xa e g ru p p i se le zi o n at i). g ru p p i p o lli n ic i: fo re st a u m id a su b tr o p ic al e (t ip o t a xo d iu m , e n g e lh a rd ia , n ys sa , c fr . r h o ip te le a ); fo re st a te m p e ra ta d i la ti fo g lie d e c id u e (c a rp in u s b e tu lu s, c a ry a , c a st a n e a , c e lt is , c o ry lu s, h a m a m e lid a c e a e in d iff ., ju g la n s, ju g la n d a c e a e in d iff ., l iq u id a m b a r, p te ro c a ry a , q u e rc u s ti p o ro b u r, q u e rc u s ti p o c e rr is , t ili a , u lm u s, z e lk o va ); fo re st a m o n ta n a e su b m o n ta n a (a b ie s, c e d ru s, p ic e a , t su g a , b e tu la , f a g u s) ; fo re st a a sc le ro fil le (q u e rc u s ti p o ile x, o le a) ; e le m e n ti xe ri c i (e rb e e d e p h e d ra ). 337plio-quaternary evolution of the high salto river valley ... of pollen of subtropical taxa as nyssa, cfr. rhoiptelea, liquidambar, engelhardia is worth being mentioned (fig. 12). in the studied pollen record gymnosperms are prevailing, even if four main important, sudden and short angiosperm arboreal pollen oscillations can be observed, the oldest of which being more marked. the importance of these changes can be singled out examining the diagram of figure 10, where pollen taxa, generally found in very different environments, ranging from mountain to arid ones, passing through temperate, subtropical, and mediterranean types, have also been grouped into five “ecological groups”. the more widespread vegetation types are two, one comprehending trees typical of temperate broadleaved deciduous forest and the other trees of mid to high elevation forest. due to the wide ecological range of living pinus species and to the fact that both pinus pollen types comprehend other genera (e.g. pinus haploxylon type includes in this paper also other genera such as cathaya; in fact, for the low degree of pollen grains, preserving its methodical distinction was not possible), pinus was not inserted in the ecological groups (sadori et al., 2009). the main vegetation changes do not consist in alternations between open and close vegetation formations, that is to say between forests and steppe formations, but just in changes in the forest composition, as xeric elements are quite absent. the rapid and consistent alternations found in the pollen record, generally speaking between conifer forests and deciduous angiosperm ones, induce to consider that consistent changes in vegetation occurred. in northern italy arboreal phases with gymnosperms and angiosperms alternately dominating characterized the glacial/interglacial cycles since the gelasian (bertini, 2003). in southern coastal italian areas, however, such cycles were featured by the alternation between steppic and arboreal phases (combourieu-nebout et al., 2004). more marked glacials/interglacials oscillations and a difference in their periodicity occurred only in the last 1 million years (leroy, 2007; raymo et al., 1997; ruddimann et al., 1989), when a change in the pattern of the orbitally driven cycles from obliquity to eccentricity occurred. these physiognomic vegetation changes are however very strong, as the forest cover changed from a mountain forest to a temperate/subtropical one. in these forest changes, temperature and not humidity, seems to have been the main limiting factor. this was not the case of the vegetation changes from glacial to interglacial periods, which occurred in the last million of years and that were mainly triggered by changes in water availability. thus, the record of marano de’ marsi appears to have been mainly deposited during a glacial period. as a matter of fact the so called interglacial periods are represented by very thin sediments horizons, in which the clear vegetation succession typical of these phases are not found (sadori et al., 2009). another substantial aspect of the vegetation recorded in the pollen diagram is that the pollen rain reflects the presence of arboreal taxa requiring different climatic features, and implying the existence of several vegetation belts. it results from the mixing of mountain, mesophilous, and subtropical elements and implies the presence of mountains in the surroundings. the hypothesis that the sediment record from marano de’ marsi has some taphonomical problems has to be advanced: 1) the pollen samples with angiosperm trees dominating show the highest number of taxa and the lowest pollen concentration values. this is in clear contradiction with what happens in the pollen records in which concentration values have been estimated; 2) the vegetation changes between glacials and interglacials are sudden and all intermediate phases are missing; 3) the clear forest vegetation successions typical of interglacial periods are also not found, these phases being recorded, ex abrupto, by mature forests; 4) there is an apparent opposite indication from the macrofossil and microfossil record, as the presence of angiosperm leaves is overwhelming even in phases in which gymnosperm pollen is dominant. the second and the third incongruities were investigated through thin section sediment analyses to check the possibility of important changes in the sedimentation pattern, aimed at explaining possible sediment gaps, not evidenced in the wide outcrop. light lithological changes showed by analyses (cosentino d., roma tre university, personal communication) have been interpreted as disconformities of a low to very low order, ranging from the 0th-order (lamination surface) to the 1st-order (set bounding surface) sensu miall (2006), consistent with the sedimentary environment. the fourth contradiction can be explained with an almost continuous local presence of angiosperms (leaves are too liable to deteriorate if transported far away) by the lake also in periods in which the regional vegetation (and therefore the pollen rain) was dominated by gymnosperms. the vegetation and floristic features of the plant fossils record frame the lacustrine sediment succession between the middle pliocene and the early pleistocene. 4.2 borgorose core the borgorose core has a 24.50 m length and was drilled at an elevation of 725 m a.s.l., close to an outcrop of lacustrine sediments. the sediments, quite homogeneous, are characterized by a higher clay content with respect to those cropping out in the marano de’ marsi investigated section, according to a frankly lacustrine origin; lithologies are mainly massive or thinly laminated marls and silty claystones. 4.2.1 paleomagnetic analyses paleomagnetic samples have been collected every 25 cm on average in order to reconstruct the magnetic susceptibility profile and magnetic polarity of the core and eventually correlate it to marano de’ marsi section. the samples have not been oriented with respect to the geographic north, but they have been marked only with respect to the top of the core. in the borgorose core, the magnetic susceptibility values are generally low and range between 81 and 249 x 10-6 si (fig. 13). these values are relatively higher than marano de’ marsi section because the sediments of borgorose core have a major content of clay minerals (i.e. paramagnetic fraction). the highest values are relative to the upper portion of the core, from 550 to 700 cm, whereas then are constant for the remaining lower portion. 338 fig. 11 marano de’ marsi (rieti, central italy). plant macrofossils. 1. liquidambar sp. 2. acer cfr. monspessulanum 3. quercus sp. 4. fagus cfr. sylvatica 5. engelhardia sp. marano de’ marsi (rieti, italia centrale). macrofossili vegetali. 1. liquidambar sp. 2. acer cfr. monspessulanum 3. quercus sp. 4. fagus cfr. sylvatica 5. engelhardia sp. e. chiarini et al. the paleomagnetic analysis has been performed on 62 out of 84 total samples of the core. all the samples have been thermally demagnetised at paleomagnetic laboratory of peveragno of the university of turin. the same standard techniques described in the previous section have been used to define the principal component and the characteristic remanent magnetization for these samples. the overall results indicate a positive inclination, with an average inclination of 52°, for all the investigated samples, suggesting a normal polarity magnetozone without magnetic reversals. the mean paleomagnetic inclination has been defined without taking into account the tectonic tilting of the succession, that is of about 20°, as measured on the nearby outcrop of the same lacustrine deposits. 4.2.2 plant microfossils pollen samples have been taken every 10 cm from 2.60 to 24.50 m. 41 samples have been analysed, but only 15 (from 3 to 8.60 m) showed a sufficient pollen content to be plotted in the diagram. known amounts of dry sediment (ca. 2 g) have been chemically processed following the treatment illustrated for the marano de’ marsi outcrop. the preservation of the pollen grains was also poor in this record, being generally degraded, corroded and broken, causing problems in the identification. the mean count of only the terrestrial spermatophytes pollen was 304 pollen grains. problems in the pollen preservation are clearly evidenced in the lower part of the core (9-24.2 m) and in the uppermost 3 m. in the related samples the very low pollen concentration values (from 100 to few thousands pollen grains/g) did not allow us to reach significant pollen counting. the total pollen concentration of the selected pollen samples varied from 9000 to 113,000 pollen grains/g at borgorose, with ap (arboreal pollen) percentages ranging from 97 to 99%. synthetical pollen percentage and total pollen concentration curves are presented in figure 14. 46 terrestrial plants pollen taxa (of which 8 herbaceous ones) were identified at borgorose. the number of pollen taxa per level varies from 12 (matching the lowest pollen concentration values) to 31. the diagram does not record either important vegetation changes or a clear vegetation development. gymnosperms pollen always prevails on that of angiosperms. pinus haploxylon type, always dominant, was mainly accompanied by picea, pinus sylvestris type, taxodium type, cedrus, and tsuga. picea, showing percentages between 8 and 19%, can be considered locally present (huntley & birks, 1983). deciduous oaks and carya show high percentage values among the angiosperms, mainly accompanied by fagus, pterocarya, juglans, ulmus, hamamelidaceae, and in minor quantities by engelhardia, nyssa and cfr. rhoiptelea. it is worth mentioning the consistent presence of water demanding trees (riparian plants), possibly indicated by the presence of taxodium type, nyssa, and carya. considering the ecological groups, mid to high elevation forest trees are more abundant than those typical of the temperate broadleaved deciduous forest. subtropical humid forest elements are always present with significant values, while sclerophyllous and xeric elements appear to be less abundant. the sediments are likely to have been deposited during a cool and wet period, and do not show the important angiosperm tree expansions featuring warmer phases. notwithstanding, angiosperms show a continuous and similar behaviour, suggesting that they were present at lower elevations and, possibly, in wet areas (see for example taxodium type) by the lake. the high amount of taxodium type pollen is the main reason for the considerable amount of subtropical humid forest taxa found in the pollen record. four common features can be singled out in the two investigated successions: 1) the scarce number of pollen taxa, that can be partially explained with the very low amount of herbs; 2) the similarity in the pollen lists of the two sites, with 43 pollen taxa in common; 3) the same list of extinct arboreal pollen taxa; 4) the contemporary presence of plants with different ecological requirements, indicating the presence of vegetation belts developed along an altitudinal gradient. similarly for the marano de’ marsi outcrop, a middle/upper pliocene or early pleistocene age appears to be consistent with the palynological data. 5. discussion and conclusions the succession cropping out in the high salto river valley, called marano de’ marsi unit in this paper, has been the object of a few works, differently from successions of fucino and middle salto valley basins. previous authors have interpreted the high salto valley succession as the result of more than one sedimentary event, probably related to pliocene (servizio geologico d ’i t a l i a , 2005), or to pliocene and to messinian (busino,1990; federici, 1990). stratigraphical and sedimentological data illustrated in this study, on the contrary, allow us to refer the unit to a single sedimentary cycle organized in a complex depositional system. recognized etheropic facies – from alluvial to lacustrine via transitional forms have been referred to a gilbert-type lacustrine delta and to small scale fan-deltas originated from the eastern border of the basin. anomalous sharp facies variations observed in the field have been reported to tectonic activity which significantly displaced the sedimentary unit. two main unconformities bound the unit: the lower one marks the erosional contact with the carbonatic bedrock; the upper unconformity corresponds to the colle vena francesca paleosurface. the prevalence of carbonatic lithologies marks a significant difference with earliest continental deposits of fucino (aielli complex, bosi et al., 1995) and middle salto valley (sabbie di piagge, bertini et al., 1986); in the lower part of the sedimentary successions of these basins, siliciclastic lithologies actually prevail, according to a wide spread of messinian turbidites in the catchment area (bosi et al., 2003) during the first erosional phase of the chain (centamore & nisio, 2002a; b). therefore it is not possible to correlate the marano de’ marsi unit with the fucino and the middle salto valley on the base of lithological affinities. in the framework of a general shortage in chronological data, paleobotanic and paleomagnetic analyses have been conducted on the finer sediments of the marano de’ marsi unit to obtain dating elements, also providing interesting paleoenvironmental and paleoclimatic results. pollen records of the two sampling sites (marano and borgorose) suggest the presence of a well developed mountain system in the surroundings, as indicated by the presence of trees belonging to different vegetation belts. pollen rain coming from mid to high elevation forest taxa is generally prevailing throughout the investigated successions. a pollen assemblage of this kind 339plio-quaternary evolution of the high salto river valley ... fig. 12 marano de’ marsi (rieti, central italy). pollen grains. 1. abies 2. nyssa 3. pterocarya 4. picea 5. cedrus 6. tsuga 7. tilia 8. engelhardia 9. cfr. rhoiptelea 10. carya 11. zelkova. marano de’ marsi (rieti, italia centrale). granuli pollinici. 1. abies 2. nyssa 3. pterocarya 4. picea 5. cedrus 6. tsuga 7. tilia 8. engelhardia 9. cfr. rhoiptelea 10. carya 11. zelkova. faults located on the eastern border of the basin. previously exposed data and the lack of compressive features inside deposits allow us to hypothesize that the marano de’ marsi unit deposited inside an intermountain continental basin, like the pliocene deposits of other basins of central apennines. the erosion of the wide colle vena francesca paleosurface testifies a significant decrease of the subsidence of this basin; during early pleistocene the subsequent settlement of corvaro intermountain basin yields a new subsident area, where the following sedimentation takes place. the whole area indeed is progressively captured by the hydrographic system of the salto river and deposits are consequently dismembered; the outlined evolution is common to that of other basins of the western apennine flank: endorheic at first and then captured and integrated in the drainage network (d’agostino et al., 2001). in reconstructing the fucino basin evolution d’agostino et al. (2001) supposed that the end of the completely internal drainage phase coincided with the capture, during the pleistocene, of a portion of the basin by regressive headward erosion of the salto river. nevertheless, a sediment supply from the eastern border of the basin has also been recognized, the facies distribution and paleocurrent directions testify a main drainage direction i.e. the gilbert-delta progradation from south-east toward north-west, thus trending like the principal fault system. these arguments highlight that at the time of marano de’ marsi unit sedimentation, the fucino and the high salto valley areas belonged to two different, isolated, basins. 340 e. chiarini et al. suggests ascribing the investigated levels to glacial periods (bertini, 2003). nevertheless, pollen typical of temperate forests (and of interglacial periods) is always present in low quantity, and, at times, overwhelming at marano de’ marsi. the moderate expansion of taxa typical of the subtropical humid forest (all extinct at present in europe) is noteworthy and useful for the chronological framing. the similarity of the pollen assemblages induces us to think that the two sediment records were deposited in the same period or at very close times. the plant fossil assemblages, the high amount of taxa at present extinct in italy indicate that the sediments were likely deposited during the middle/upper pliocene or the early pleistocene. as no magnetic reversals are present in the investigated section, the combination of pollen and paleomagnetic data allows to constrain both records to gauss chron (middle pliocene) or olduvai/reunion subchrones (late pliocene). a close comparison (see sadori et al., 2009) with other italian palynological records of pliocene and pleistocene age (urban et al., 1983; arias et al., 1990; suc et al., 1995; bertini, 2000, 2001, 2003) seems to better frame both successions in the subchrones of late pliocene, more likely to olduvai one, for its longer duration. the possibility that the records deposited during the gauss chron cannot be, definitely, excluded. the presence of pliocene continental deposits is widely documented in the central apennines and it has been related mainly to extensional tectonic activity: since pliocene a prevailingly lacustrine sedimentation took place in the main intermountain basins like the turano valley, the middle salto valley and the fucino basins (bosi et al., 1995; bosi et al., 2003; galadini & m e s s i n a , 2004). intermountain basins in central apennines are thought to be progressively younger eastward, for the effects of extensional tectonic migration from the western sectors to the eastern ones (cavinato & de celles, 1999; galadini & messina, 2004). the quite complex structural setting, outlined in this paper, neither allows us to define the configuration of the basin where the marano de’ marsi unit sedimented, nor to certainly establish which tectonic structures guided the basin settlement. geological field data and ams results suggest that the marano de’ marsi unit was deformed in an extensional tectonic regime, with a stretching direction oriented ne-sw. the development of a gilbert-type delta also implies the occurrence of a steep margin; additionally the presence of slumps and big boulders in some horizons of succession indicate a tectonic instability along the depositional slope, giving value to the tectonic control on the basin evolution. finally the structural setting of succession shows a general ne tilting. all these features are consistent with the activity of fig. 13 stratigraphic log (a) and magnetic susceptibility profile (b) for borgorose core. colonna stratigrafica schematica della sezione di borgorose (a) e profilo di suscettività magnetica (b). 341plio-quaternary evolution of the high salto river valley ... f ig . 1 4 b o rg o ro se (r ie ti , c e n tr a li ta ly ). p o lle n d ia g ra m (s e le c te d ta xa a n d g ro u p s) . p o lle n g ro u p s a re lis te d in f ig . 1 2 . b o rg o ro se (r ie ti , it al ia c e n tr al e ). d ia g ra m m a p o lli n ic o (t a xa e g ru p p is e le zi o n at i). p e r ig ru p p ip o lli n ic iv e d il ’e le n c o in f ig . 1 2 . 342 e. chiarini et al. acknowledgments the authors are very grateful to a. bertini and p. messina for the useful discussions and the critical review of the paper and f. cifelli for paleomagnetic sampling. references arias c., bigazzi g., bonadonna f.p., iaccarino s., urban b., dal molin m., dal monte l. & marzolini m. 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(1995) environmental magnetism: past, present, and future. j. geophys. res. b, 100, 2175–2192. 343plio-quaternary evolution of the high salto river valley ... ms. ricevuto l’8 aprile 2009 testo definitivo ricevuto il 29 ottobre 2009 ms. received: april 8, 2009 final text received: october 29, 2009 base cambiamenti dell’uso del suolo e aumento dell’attività franosa nel territorio di rocchetta sant’antonio (appennino dauno) caterina lamanna1, domenico casarano1 & janusz wasowski1 1cnr-irpi (bari), e-mail: cate.lama@tiscali.it riassunto: lamanna c. et al., cambiamenti dell’uso del suolo e aumento dell’attività franosa nel territorio di rocchetta sant’antonio (appennino dauno). (it issn 0394-3356, 2009). sono state studiate le variazioni dell’attività franosa nell’intero territorio comunale di rocchetta sant’antonio (appennino dauno), nel periodo 1976-2006. la mappatura dei fenomeni franosi è stata condotta facendo principalmente uso di foto aeree e di immagini satellitari ad alta risoluzione (ikonos). le fotografie aeree sono state analizzate in modalità stereoscopica, mentre l’immagine ikonos, dopo il pan-sharpening e l’ortorettificazione, è stata sovrapposta al dtm e visualizzata in tre dimensioni. dallo studio è emerso che la frequenza spaziale delle frane attive nel 2006 è del 160% più alta che all’inizio del periodo di studio, sebbene i dati pluviometrici assumano valori confrontabili nelle due date. dopo il 1976, anno in cui la cee stabilì di concedere incentivi per ogni ettaro di terreno coltivato a grano duro, si è peraltro verificato un incremento di circa il 46% nell’estensione areale del seminativo, soprattutto per le coltivazioni cerealicole. pertanto la più alta suscettibilità alle frane può essere legata al cambio di uso del suolo; infatti i massimi valori assoluti di densità delle frane attive si sono osservati sui terreni divenuti agricoli dopo il 1976 (“nuovo seminativo”), e sui seminativi si è osservato un incremento della franosità nettamente maggiore rispetto alle aree mai coltivate. i terreni divenuti coltivati dopo il 1976 erano già a quella data più franosi dei terreni già seminati. inoltre l’aumento della franosità sul nuovo seminativo è dovuto all’estensione delle colture cerealicole e foraggere su terreni con pendenza mediamente superiore a quella dei terreni già coltivati: il vecchio seminativo era per il 25% su pendenze superiori ai 10° e quasi mai oltre i 15°, mentre il nuovo seminativo è per il 45% su pendenze oltre i 10° e per quasi il 10% oltre i 15°. le coltivazioni su pendenze elevate, marginali nel 1976, hanno finito per riguardare porzioni significative del territorio. quindi, l’incremento delle frane attive è da attribuirsi, almeno in parte, all’estensione delle coltivazioni su terreni più ripidi e già intrinsecamente meno stabili prima di essere coltivati. d’altra parte, le precipitazioni superiori alla media negli inverni tra il 2003 e il 2006, con l’occorrenza di eventi intensi, sono il principale fattore causativo/innescante dei più recenti movimenti franosi. i risultati di questo studio suggeriscono che per pendii profondamente modificati dall’uomo negli ultimi decenni, si deve considerare l’effetto combinato delle variazioni climatiche e dell’uso del suolo per evitare il rischio di sovrastimare l’impatto sulla franosità del solo aspetto climatico. abstract: lamanna c. et al., land use change and increase in landslide activity in the rocchetta s. antonio area (daunia apennines). (it issn 0394-3356, 2009) we examine temporal variations in landslide activity in the context of land use changes and precipitation characteristics in the northwestern part of the apulia region (southern italy). the period considered is from 1976 to 2006. the main study area (72 km2) includes the municipal territory of rocchetta s. antonio (fg), assumed to be a representative portion of the daunia apennines. despite the moderate elevation (from 250 to about 1000 m), the daunia mountains are known for their susceptibility to landsliding, with rainfall events and unwise man activity being the main triggering/causative factors. only the steepest, highest elevation areas include a significant percentage of arboreous land. elsewhere, especially where clay-rich units predominate, the vegetation cover is represented mainly by cultivated land (cereals) and locally by grass land. the rocchetta s. antonio territory is distant only few tens of km from the adriatic coast, and, as the entire daunia region, is characterised by a mediterranean semiarid (sub-apennine) climate with total annual rainfall that typically varies from 600 to 750 mm. the clay-rich flysch formations are widespread in daunia and that makes slopes susceptible to landsliding. the presence of intensely deformed geological units is another factor predisposing to instability. to investigate the differences between historical (1976) and recent (2006) landsliding we first compiled two landslide activity maps. the 1976 landslide inventory was obtained through a systematic interpretation of 1:25000 scale aerial photographs and the 2006 inventory was based on the interpretation of high resolution (1 m pixel) ikonos satellite imagery. for simplicity a distinction was made only between active and inactive landslides. we followed the geomorphic criteria typically adopted for the recognition of landslides and their state of activity from air-borne imagery. to facilitate the interpretation the satellite imagery was first orthorectified and pan-sharpened. then natural colour imagery was draped over a detailed dtm (with 5 m grid size) generated from recent topographic maps at 1:5000 scale. for comparative analysis the information on landslides was presented by quantifying area frequency of landslides (percentage of the total study area occupied by landslides) and their density (number of landslides per km2). in particular, the comparison of the 1976 and 2006 landslide inventories shows large increase in number of active landslides (from 5.7/km2 to 34.4/km2 in terms of density), which corresponds to 160 % increase in aerial frequency. to assess land use change occurred in the same 30 year period we used again 1976 aerial photos and produced a map of historical land use. a map of recent land use was prepared using aster satellite imagery. this imagery was preferred over ikonos data, because the acquisition period of the aster imagery (summer, after harvest) resulted more suitable for land use classification based on automatic supervised procedure. the following three major groups or classes were distinguished: i) agricultural land (sown fields with mainly cereal cultivation ploughing), which represents by far the predominant group ii) arboreous land, including dense shrub and iii) other (including uncultivated and bare land, grass land, pasture, and man-made). the selection of these three groups was driven by the presence of few predominant classes of land cover and land use, as well as by their potential impact on shallow landsliding. to quantify the temporal variations in land use from 1976 to 2000 the map data were expressed as percentage of areal frequency. the results show that about 52% of the land has been used as sown fields in the seventies and that by the year 2000 the percentage increased to 75%. the influence of the land use change on mass movement activity is evident when considering the distributions of active landslides on sown fields. in particular, the results demonstrate that the recent (2006) very high density (7.6%) of active landslides in the areas that have become sown after 1976 (new sown) can be linked to the originally high susceptibility of those areas to landsliding (2.9%), exceeil quaternario italian journal of quaternary sciences 22(2), 2009 139-156 140 c. lamanna et al. 1. introduzione è noto che i cambiamenti di uso del suolo possono influenzare l’instabilità dei pendii su scala locale e regionale, ma si riconosce anche che i loro effetti sono spesso scarsamente compresi e difficili da quantificare (ad es. gostelow & wasowski, 2004). nelle regioni montuose popolate, le frane superficiali spesso sono prodotte dall’interazione tra l’ambiente e l’azione antropica e molti studi hanno mostrato un’evidente relazione tra l’uso del suolo e la stabilità dei versanti (ad es. degraff & canuti, 1988; begueria, 2006). in particolare, il disboscamento, gli incendi e le coltivazioni sulle colline sono considerati i più significativi fattori predisponenti (sidle et al., 1985; cannon, 2000). le aree con vegetazione fitta sono meno suscettibili ai movimenti di versante rispetto a quelle con vegetazione sparsa (gokceoglu & aksoy, 1996). secondo selby (1993), gli alberi che ricoprono le colline aumentano la resistenza al taglio dei suoli per circa il 60%. mehrotra et al. (1996) hanno mostrato che l’attività delle frane aumenta di circa il 15% dove la copertura della vegetazione originale è stata eliminata o alterata. in questo lavoro sono studiate le relazioni tra i fattori ambientali dinamici (cambiamenti di uso del suolo e precipitazioni) e l’attività franosa nei monti dauni. a dispetto del moderato rilievo e della piovosità annuale relativamente bassa, i monti dauni sono noti per la loro suscettibilità al dissesto franoso (ad es. cotecchia, 1963). la regione ha subito una considerevole deforestazione negli ultimi secoli e questo può avere predisposto condizioni di diffusa franosità nelle aree rurali (ad es. parise & wasowski, 2000). in particolare, sono state studiate le variazioni storiche dell’attività franosa occorse dal 1976 al 2006, nel territorio comunale di rocchetta sant’antonio, nell’appennino dauno (fig. 1). il 1976 è una data chiave, in quanto la cee in quell’anno stabilì di concedere un aiuto per ogni ettaro di terreno coltivato a grano duro (regolamento (cee) n. 1143/76). il regolamento ha favorito l’aumento della superficie destinata alla cerealicoltura e la puglia è diventata la principale produttrice di grano duro in italia (conforti, 2002). importanti sono anche le trasformazioni che hanno subito le tecniche di lavorazione dei terreni acclivi con la diffusione delle macchine agricole, in seguito agli incentivi della cee. con i mezzi meccanici moderni, si raggiungono profondità di aratura di 55-60 cm, si forma la “soletta di lavorazione” (pellicola a bassa permeabillità sotto lo strato lavorato) e di conseguenza si ha un rallentamento della percolazione dell’acqua e un ristagno a livello della soletta di lavorazione che favorisce lo slittamento dello strato sovrastante smosso dall’aratura (gisotti e zarlenga, 2004). il territorio di rocchetta, prevalentemente rurale, è noto per i ricorrenti problemi di frane e può pertanto essere considerato come porzione rappresentativa dei monti dauni. vi è evidenza di un incremento della franosità negli ultimi anni e, sebbene manchino studi dettagliati, è opinione comune tra la popolazione locale che una parte di responsabilità sia da attribuire ai cambiamenti climatici. è noto che la suscettibilità al dissesto non è semplice da mappare e modellizzare, anche quando i fattori fisici che la controllano sono conosciuti relativamente bene. pertanto, per dimostrare l’influenza delle precipitazioni e dell’uso (e copertura) del suolo sulla franosità, si sono ottenute le mappe delle frane e di uso del suolo per due date diverse (1976 e 2006). la variazione nell’attivita franosa documentata nei 30 anni considerati è stata analizzata anche tenendo conto dell’andamento delle precipitazioni negli ultimi decenni. l’analisi dei cambiamenti di uso del suolo nell’area di studio è essenziale per un‘esatta comprensione del motivo per cui, nel periodo esaminato, il problema della stabilità dei versanti si sia aggravato. particolare attenzione è stata prestata alle attività antropiche, specialmente alle pratiche agricole, e alle precipitazioni, non solo perchè anche in tempi brevi queste possono subire variazioni significative nello spazio e nel tempo, ma anche perché è stato riconosciuto che i cambiamenti di uso del suolo rappresentano un fattore importante che influenza lo sviluppo di frane indotte dalle precipitazioni (glade, 2003). oltre ai fattori dinamici (uso del suolo e piovosità), si sono considerati alcuni fattori geologici e geomorfologici che, anche se praticamente costanti nell’arco di tempo esaminato, possono dare ulteriori informazioni circa la comprensione dei processi che regolano la stabilità dei pendii nell’area di studio. ding even the area frequency of failures in the fields already sown in 1976 (old sown, 1.8%). in fact, new cultivated land, which is on steeper slopes than older fields, had a landslide density 55% higher than did the older fields in 2006. furthermore, the increase in the frequency of active landsliding observed on both old and new sown fields has been greater than elsewhere (remaining areas). all this demonstrates that land use changes occurred between 1976 and 2006, and in particular the increases in the areal extent of sown fields, have negative influence on the stability of slopes in the study area. clearly, the frequency of slope failures in time results from an interaction of many variables, and it is well known that the most significant temporal controls are often those related to rainfall-induced processes. although relations between climatic events and landslide occurrence can be very complex, our field observations indicated that in daunia highest landslide activity typically occurs in late winter time. indeed, the majority of shallow slope failures registered in 2006 were triggered by late february and march rainfalls that followed a wet winter period. a comparison of the precipitation characteristics in 1976 and 2006 did not show major differences. in particular, by taking into account potential evapotranspiration in the months preceeding the two landslide inventorying periods we demonstrate that potential water input to the soil differed by about 20%. in summary, the results of this work demonstrate clear relations between the land-use changes in the period 1976-2006 and the recent high landslide activity. we thus stress that for hillslope areas profoundly altered by man in the recent decades, the effects of changes in both land use and rainfall patterns have to be considered to avoid a risk of overestimating (or underestimating) the relative impact of climate change or variability on landslide activity. parole chiave: frane attive, uso del suolo, appennino dauno, ikonos. keywords: active landslides, land use, daunia apennines, ikonos. 2. inquadramento geografico, geologia e franosità 2.1 inquadramento geologico e geomorfologico generale l’area presa in esame presenta quote variabili tra 170 e 770 metri s.l.m. e comprende il territorio comunale di rocchetta sant’antonio, paese di modeste dimensioni, posto sulla sommità di un piccolo rilievo dell’appennino dauno. l’appennino dauno appartiene all’area di transizione tra la parte più orientale della catena appenninica, ricadente nella provincia di foggia, e la parte più occidentale dell’avanfossa (tavoliere della puglia) (crostella & vezzani, 1964; mostardini & merlini, 1986; dazzaro et al, 1988; ciarcia et al., 2003). le unità della catena, che interessano prevalentemente l’area di studio, sono rappresentate da formazioni essenzialmente torbiditiche: “flysch rosso” (cretaceo superioreoligocene) e flysch numidico (miocene inferiore) attribuite in gran parte al bacino lagonegrese, e flysch di faeto (miocene medio-superiore) appartenente alle unità irpine (di nocera & torre, 1987). litologicamente il “flysch rosso” è costituito da argille grigie o variamente colorate, in strati sottili ed alternati a marne, calcari pulverulenti ed argilliti fogliet141cambiamenti dell’uso del suolo e aumento dell’attività franosa ... tate, calcilutiti tipo scaglia, calcareniti con liste di selce e brecciole (di nocera & torre, 1987). su questi terreni giace il flysch numidico. quest’ultimo è costituito essenzialmente da quarzoareniti e quarzosiltiti di colore grigio, rossastro per alterazione, con sottili intercalazioni di marne argillose varicolori nella parte bassa della successione. a luoghi si osservano arenarie grossolane mal classate, che passano in alto ad arenarie fini e quindi a quarzosiltiti; i livelli di argilla marnosa, per lo più scagliosa, non mostrano una frequenza ritmica (di nocera & torre, 1987). il flysch di faeto è costituito da un’alternanza di calcareniti, calcari marnosi, brecciole con interstrati di marne e argille. la composizione prevalentemente calcarea è dovuta principalmente ad apporti derivanti da una piattaforma carbonatica identificabile con quella apula (dazzaro & rapisardi, 1987). il flysch di faeto poggia con contatto stratigrafico sui livelli sommitali, marnoso-argillosi del “flysch rosso”; quasi sempre però il rapporto tra le due unità risulta disarticolato dagli eventi tettonici pliopleistocenici (di nocera & torre, 1987). infine nella parte nord della zona di studio è presente l’unità di ariano caratterizzata da una notevole variabilità delle litofacies: conglomerati, arenarie, calcafig. 1 immagine da satellite ad alta risoluzione del territorio comunale di rocchetta sant’antonio. si nota l’uso del suolo prevalentemente agricolo (il riquadro mostra l’ubicazione dell’area di studio in italia meridionale). high resolution satellite image of rocchetta s. antonio. note predominantly agricultural land use (inset shows location in southern italy). 142 reniti, sabbie, argille e argille marnose (di nocera & torre, 1987). la presenza di terreni fortemente deformati e tettonizzati, per gli intensi movimenti tettonici a cui sono stati soggetti e che ne hanno modificato profondamente il loro assetto originario, e l’elevata percentuale di componente argillosa contribuiscono a rendere il territorio suscettibile a franare (fig. 2). a ciò si aggiunge l’azione erosiva di alcuni corsi d’acqua, molti dei quali a deflusso stagionale, che solcando le valli rendono ancora più soggetta ai dissesti l’area di studio. per lo scopo di questo studio, le unità geologiche sono state raggruppate in 9 categorie (fig. 3); il criterio usato per la suddivisione è quello della similarità litologica che presuppone il comparabile comportamento geotecnico. la maggior parte dell’area (circa 75%) è ricoperta da terreni ad alto contenuto argilloso. in particolare, le unità del flysch rosso (prevalentemente argille e argilliti), corrispondenti al complesso indifferenziato (malatesta et al., 1967), affiorano su oltre il 50% dell’area di studio. anche se tali terreni danno origine a rilievi collinari con moderate pendenze, essi comprendono la maggior parte delle frane censite nella zona. i due gruppi che includono il flysch del miocene, uno composto da calcari marnosi, arenarie e argille, e l’altro composto principalmente da arenarie con intercalazioni di argille marnose, occupano, rispettivamente circa il 23 e il 10% dell’area di studio. i restanti gruppi litologici (sabbie, argille, argille marnose e conglomerati del pliocene; depositi alluvionali terrazzati del pleistocene-olocene; detriti di falda recenti ed attuali dell’olocene; alluvioni recenti ed attuali), rappresentano, ognuno, meno del 10% dell’area. le categorie dove prevale il contenuto litoide sono meno soggette all’instabilità. tuttavia, crolli si manifestano talora nelle rocce arenacee o calcaree. tali rocce in corrispondenza di limitati affioramenti di calcari, brecce e arenarie sovrastanti i terreni argillosi rendono la sommità di alcune alture aspra e scoscesa. 2.2 frane i movimenti di massa sono comuni nell’intera regione dauna (ad es. zezza et al., 1994), tuttavia sono relativamente pochi gli studi pubblicati sulle frane nei monti dauni (ad es. i o v i n e et al., 1996; p a r i s e & wasowski, 2000; wasowski et al., 2007). ci sono oltre 20 centri abitati sulle sommità delle colline daune, molti dei quali hanno risentito in passato di problemi di instabilità dei pendii. sebbene la documentazione specifica riguardante l’esatta datazione dei singoli eventi franosi sia disponibile solo raramente, dalle informazioni acquisite presso gli enti locali e dalle dichiarazioni degli abitanti, risulta che negli ultimi anni vi sia stato un aumento dei movimenti di massa in diverse aree urbane e periurbane. è probabile che la stabilità dei pendii ai confini dei centri urbani posti sulle sommità sia gradualmente peggiorata a causa dello sviluppo residenziale e della crescita delle infrastrutture negli ultimi decenni. questo potrebbe aver portato in alcuni casi alla riattivazione di vecchie frane preesistenti. inoltre, l’espansione urbana verso pendii con stabilità marginale ha probabilmente prodotto come risultato l’incremento di nuovi dissesti. negli ultimi anni, inoltre, numerosi e talora estesi movimenti di massa hanno anche determinato perdite delle colture, soprattutto cerealicole, danni alle case rurali e reso impraticabili alcune strade. per esempio, il 7 marzo 2005 una grande frana, provocata dalle abbondanti piogge, determinò danni al tratto dell’autostrada a16 tra candela e lacedonia con conseguente chiusura al traffico e deviazione. tali eventi hanno ravvivato l’attenzione sulla stabilità dei versanti in questa zona tra le autorità locali e nazionali, nonchè tra i ricercatori. mossa et al. (2005) hanno presentato un censimento delle frane, realizzato in ambiente gis, riguardante l’area confinante a nord-ovest con il territorio comunale di rocchetta sant’antonio. la frequenza areale delle frane superiore al 20% (sia attive che vecchie) ottenuta sull’intera area di 132 km 2 dimostra l’elevata suscettibilità dei pendii. i risultati inoltre hanno mostrato che l’incidenza delle frane è più alta nella classe di pendenze comprese tra 10 e 15° seguita da quelle 5-10° e 15-20°. questo indica una resistenza molto bassa (residuale) dei materiali del pendio e suggerisce che una porzione significativa dei dissesti può risultare dalla riattivazione di frane preesistenti. in quefig. 2 “flysch rosso” con blocchi calcarei nel territorio comunale di rocchetta sant’antonio. si notano chiari segni di instabilità. “flysch rosso” with calcareous blocks in the area of rocchetta s. antonio. note clear signs of slope instability. c. lamanna et al. 143 sto senso, frequenti visite su campo condotte negli ultimi anni nell’appennino dauno confermano che le rimobilitazioni stagionali (perlopiù in inverno e primavera) di frane preesistenti sono comuni. nondimeno, anche una franosità superficiale di prima attivazione è diffusa. in molti casi il fattore scatenante sembra collegato alle precipitazioni. per quanto riguarda l’influenza della litologia sulla franosità nell’area di studio, essa ovviamente ha un impatto sulla distribuzione spaziale delle frane (in particolare a scala locale) ma non sulla variazione temporale dell’attività franosa nei trent’anni considerati. infatti, in questo periodo di tempo le analisi delle relazioni tra franosità e litologia hanno mostrato che ci sono comparabili aumenti della franosità attiva in tutte le classi litologiche considerate (lamanna, 2008). quindi il fattore litologia può essere assunto costante coerentemente con gli scopi di questo lavoro. 3. frane e cambio di uso del suolo 3.1 generalità per tracciare un quadro completo dei fenomeni di dissesto nel territorio è stato necessario acquisire dati per mezzo del rilevamento effettuato in campagna e con l’ausilio dell’interpretazione delle foto aeree e delle immagini da satellite. in tal modo sono state prodotte carte inventario dei movimenti di massa e carte tematiche relative ad alcuni fattori correlati all’attività franosa come l’uso del suolo. il rilevamento di campagna, effettuato nel 2005, su un’area più ampia di oltre 300 km 2 ha registrato una densità di 3.2 frane/km 2 , la maggior parte delle quali attive, ed una frequenza areale pari al 5.4%. e’ emerso che tra i cinque territori comunali esaminati, quello di rocchetta sant’antonio, oltre a presentare la più alta densità di frane, 6.2 per km 2 , e la più alta frequenza fig. 3 mappa geo-litologica dell’area di studio – territorio comunale di rocchetta sant’antonio; geologia modificata da malatesta et al. (1967) e jacobacci & martelli (1967). legenda: 1) alluvioni recenti ed attuali; 2) detriti di falda recenti ed attuali (olocene); 3) depositi di frane; 4) depositi alluvionali terrazzati (sabbie, ghiaie e argille) (pleistocene-olocene); 5) sabbie, argille, argille marnose e conglomerati (pliocene); 6) arenarie includenti intercalazioni di argille scistose marnose (miocene); 7) calcari marnosi, arenarie e argille scistose (miocene); 8) complesso indifferenziato (brecce calcaree, calcareniti) (paleogene); 9) complesso indifferenziato (principalmente argille scistose e argille scistose marnose, e secondariamente calcari, calcareniti, brecce, arenarie) (cretaceo superiore-paleogene); 10) faglie; 11) faglie supposte. geo-lithological map of the study area municipal territory of rocchetta s. antonio; geology modified after malatesta et al. (1967) and jacobacci & martelli (1967). legend: 1) recent alluvium; 2) slope debris (holocene); 3) landslide deposit; 4) alluvial terrace deposit (sand, gravel and clay) (pleistocene-holocene); 5) sand, clay, marly clay and conglomerate (pliocene); 6) sandstone including marly clay-shale intercalations (miocene); 7) marly limestone, sandstone and clay-shale (miocene); 8) undifferentiated complex (limestone breccia, calcarenite) (paleogene); 9) undifferentiated complex (primarily clay-shale and marly clay-shale, and secondarily limestone, calcarenite, breccia, sandstone) (late cretaceouspaleogene); 10) fault; 11) fault-inferred. cambiamenti dell’uso del suolo e aumento dell’attività franosa ... 144 areale (11.1%), comprende anche notevoli danni alle infrastrutture, in particolare alle vie di comunicazione (fig. 4). si è quindi ritenuto di focalizzare lo studio sul territorio comunale di rocchetta (72 km 2 ) (fig. 1). in quest’area, solo le sommità più ripide ed elevate includono una percentuale significativa di suolo arboreo. altrove, specie dove predominano unità prevalentemente argillose, la copertura vegetale è rappresentata soprattutto da coltivazioni cerealicole e localmente da pascolo nelle zone con vegetazione erbacea intercalate da radi cespugli. le aree incolte sono molto limitate e corrispondono ad affioramenti di litotipi più rocciosi. la densità relativa di insediamenti urbani e rurali, strade ed altre infrastrutture è molto bassa. il territorio di rocchetta è caratterizzato da clima mediterraneo (subappenninico) con piovosità annua tipicamente compresa tra 600 e 750 mm. gli inverni sono umidi e miti, con precipitazioni nevose molto limitate. le estati sono tipicamente calde e asciutte. 3.2 materiali e metodi qualsiasi approccio metodologico, finalizzato alla realizzazione di uno studio sulla variazione della franosità nel tempo e sulle sue cause, prevede un accurato catalogo e un’analisi dei movimenti di massa in atto nell’area. il metodo più comune per l’acquisizione dei dati terrestri e la realizzazione di carte inventario dei fenomeni franosi è quello di mettere insieme mappe derivanti da documenti di varia origine, da rilevamenti sul campo e dall’interpretazione ed elaborazione di dati telerilevati (foto aeree ed immagini da satellite). mantovani et al. (1996) considerarono che mentre le tecniche di fotointerpretazione erano ben note, l’utilizzo delle immagini satellitari era meno diffuso. in particolare, gli autori constatarono che solo un numero limitato di ricercatori sfruttava completamente immagini multispettrali. oggi le immagini da satellite possono costituire una valida alternativa alle foto aeree, e trovare un impiego sempre maggiore per lo studio dei movimenti franosi, grazie alla disponibilità crescente di dati con una risoluzione molto alta (nichol et al., 2006). 3.2.1 dati utilizzati le informazioni ed i data set principali sfruttati nel presente lavoro sono qui elencati: base topografica alle scale 1:5000, 1:2000 e 1:500, del 2002; modello digitale del terreno (dtm) generato dalle mappe in scala 1:5000 citate; fotografie aeree cartacee in b/n, in scala 1:25000, di fig. 4 in alto: muro di sostegno travolto da una frana; si osservano frane superficiali in terreni essenzialmente argillosi del “flysch rosso” (valle capo diavolo, rocchetta sant’antonio). in basso: sede stradale (sp99bis rocchetta-rocchetta scalo) danneggiata da un movimento franoso. upper: photo showing retaining wall sheared by a deep slope movement (foreground) and shallow landslides in clay-rich “flysch rosso”materials in valle capo diavolo, rocchetta s. antonio (background). lover: sp99bis rocchetta-rocchetta scalo road damaged by a landslide. c. lamanna et al. luglio 1976; immagine multispettrale del satellite aster (usando le bande nel visibile e quella nel vicino infrarosso a 15 m di risoluzione), di luglio 2000; immagine multispettrale del satellite ikonos con risoluzione di 1 m in modalità pancromatica, di aprile 2006; dati termometrici mensili e pluviometrici giornalieri. l’interpretazione delle immagini telerilevate si è avvalsa inoltre delle conoscenze locali della geologia e franosità nella zona di studio acquisite durante i numerosi rilievi su campo svolti in situ negli anni 2005-2007. l’analisi, riguardante l’intero territorio comunale di rocchetta sant’antonio, è stata eseguita usando le tecniche gis (geographic information system), in quanto queste ultime oltre a facilitare la preparazione delle carte stesse con maggiore efficienza ed accuratezza rispetto al passato, hanno facilitato l’esame delle relazioni spaziali e temporali tra frane e uso del suolo permettendo di integrare dati di diversa origine, scala, formato e sistema di riferimento cartografico. 3.2.2 metodologia di realizzazione delle carte della franosità per ottenere un catalogo storico delle frane si è effettuata una interpretazione stereoscopica delle foto aeree del 1976. per realizzare le carte delle frane, le fotografie aeree del 1976 sono state sottoposte a scansione, ortorettificate e infine mosaicate in modo da ottenere un’unica immagine dell’area. dopo aver identificato sui fotogrammi i movimenti franosi questi sono stati importati in ambiente gis. nei rilevamenti di campagna si sono osservate frane di varie dimensioni, anche della lunghezza delle decine di metri o inferiore. per poter effettuare la mappatura di movimenti franosi anche di piccole dimensioni, e ottenere un catalogo recente completo delle frane si sono adoperate immagini ikonos ad alta risoluzione, acquisite all’inizio della primavera del 2006. utilizzando una singola immagine ikonos e non la molto costosa coppia stereo, si sono riconosciute essenzialmente le frane attive s.l. e la successiva analisi comparativa con i dati del 1976 si è basata solo su questa categoria di movimenti franosi. invece la mancanza dell’osservazione stereoscopica non ha permesso l’individuazione di diverse frane inattive s.l. riconosciute in sito. anche se non ci sono ancora molti esempi in letteratura di applicazioni dell’immagine ikonos per l’individuazione delle frane, alcuni autori (nichol et al. 2006; van westen et al. 2008) hanno dimostrato chiaramente l’utilità di questo tipo di dati ottici. la mappatura delle frane è stata facilitata dalla visualizzazione tridimensionale dell’immagine sovrapposta al dtm dettagliato. inizialmente, sono state ortorettificate le singole bande (bande 1 4 e pancromatica). successivamente, le immagini sono state elaborate per mezzo della procedura pan-sharpening che ha permesso di osservare le immagini ikonos in colori naturali compositi con 1 metro di risoluzione. l’immagine ikonos, pan–sharpened ed ortorettificata, visualizzata in tre dimensioni in colori naturali, rende chiaramente osservabile la posizione delle frane sui versanti, in particolare di quelle attive (fig. 5). tutte le frane osservate sono state riprodotte sulle carte digitalizzandole sull’immagine ikonos ortorettificata. 3.2.3 metodologia di realizzazione delle carte dell’uso del suolo per mappare l’uso del suolo nel 1976 si sono utilizzate le stesse foto aeree adoperate per realizzare la carta delle frane dello stesso anno. poiché i tentativi di utilizzare procedure automatiche di classificazione hanno fornito risultati inaffidabili, le classi di uso del suolo sono state estratte tramite fotointerpretazione. si sono distinte tre classi principali: “terreno agricolo” (seminativo con coltivazioni, soprattutto cerealicole, comportanti aratura) che rappresenta di gran lunga il gruppo prevalente (fig. 1); “terreno alberato”, includente le formazioni vegetali che presentano copertura sufficientemente densa ed estesa da attenuare l’impeto dell’acqua che scorre in superficie (boschi, macchia, frutteti, alberature adiacenti alle strade e ai corsi d’acqua); 145 fig. 5 particolare dell’immagine ikonos ortorettificata pan-sharpened sovrapposta al dtm (le altezze sono state esagerate di 3 volte): si osservano in dettaglio le frane attive. zoom of pan-sharpened and orthorectified ikonos image overlapped on dtm (3x vertical exaggeration): active landslides are clearly visible. cambiamenti dell’uso del suolo e aumento dell’attività franosa ... “altro” (comprendente incolto, suolo nudo, pascolo e infrastrutture). la scelta dei tre gruppi è stata dettata dai principali tipi di copertura del suolo e di uso del suolo presenti nell’area di studio, come anche dal loro potenziale impatto sulle frane superficiali. inizialmente, la realizzazione della mappa dell’uso del suolo recente è stata tentata utilizzando l’immagine ikonos. tuttavia, poichè si è utilizzata la classificazione automatica (con procedura supervisionata), l’immagine ikonos non ha fornito risultati affidabili (l’acquisizione è avvenuta quando le colture cerealicole e foraggiere erano ancora verdi, con piante di bassa altezza e quindi facilmente confondibili con le aree incolte ed i pascoli). pertanto si è preferito usare l’immagine aster dell’estate 2000, che ha consentito una classificazione automatica dell’uso del suolo (i campi a cereali presentavano una risposta spettrale nettamente diversa dalle zone incolte). un esame qualitativo delle immagini ha suggerito che tra tra il 2000 ed il 2006 vi sono stati cambi di uso del suolo di modesta entità. infatti non risulta che l’area negli ultimi anni sia stata interessata da eventi catastrofici (es. incendi) o da cambiamenti importanti nelle politiche di uso del suolo. pertanto la carta dell’uso del suolo derivata da aster è stata assunta valida anche per il 2006. la classificazione con procedura supervisionata dell’immagine aster è stata eseguita usando tre bande (due nel visibile e una nel vicino infrarosso, vnir). 3.3 distribuzione delle frane al fine di studiare la differenza tra la distribuzione delle frane del 1976 e quelle del 2006 si sono realizzate due serie di mappe dell’attività franosa (cf. soeters & van westen, 1996), derivate da foto aeree ed interpretazione di immagini satellitari. si è seguito il criterio geomorfico tipicamente adottato nella ricognizione delle frane e del loro stato di attività da immagini aeree (ad es. wieczorek, 1984). tenendo conto dello scopo di questo studio si è distinto esclusivamente tra frane attive s.l. ed inattive s.l. la terminologia adottata è ispirata alle indicazioni del wp/wli (1993), leggermente modificate. in particolare, per il fenomeno attivo s.l. intendiamo una frana che si è mossa l’ultima volta entro l’ultimo ciclo stagionale o al massimo nel corso del penultimo. non pretendiamo di distinguere dalle immagini telerilevate le frane attive s.s. (cioè quelle che erano in movimento al momento dell’acquisizione delle foto aeree o immagini satellitari) e i fenomeni sospesi, i.e. quelli che si sono mossi durante gli ultimi due cicli stagionali. per 146 fig. 6 carta delle frane del 1976 e reticolo idrografico sovrapposti al dtm nel territorio di rocchetta. legenda: 1) frane attive nel 1976; 2) frane inattive nel 1976; 3) reticolo idrografico. map of 1976 landslides and hydrographic network draped over dtm (rocchetta s. antonio territory). legend: 1) active landslides in 1976; 2) inactive landslides in 1976; 3) drainage network. c. lamanna et al. frane inattive s.l., in questo lavoro, si intendono quelle che si sono mosse l’ultima volta prima degli ultimi due cicli stagionali; la conoscenza pluriennale della zona di studio suggerisce che una buona parte di queste frane potrebbe essere classificata come fenomeni quiescenti. una caratteristica degli inventari delle frane inattive è che l’evidenza sul terreno dell’esistenza di molte frane più piccole viene persa a causa di modifiche successive come processi erosivi, crescita della vegetazione, influenza antropica inclusi i lavori di aratura. pertanto, con il passare del tempo, i limiti delle frane in genere si distinguono sempre più difficilmente anche dalle fotografie aeree e l’inventario delle frane inattive è più soggetto ad errori ed è meno completo. pertanto, le stime riguardanti la variazione dell’attività franosa nel periodo di 30 anni considerato in questo studio si basano esclusivamente sui dati relativi ai fenomeni attivi. e’ noto che molti fattori influenzano l’affidabilità, la completezza e la risoluzione di una carta inventario, tra cui: la freschezza delle frane e l’età, la qualità e la scala delle immagini telerilevate, la complessità morfologica e geologica dell’area di studio, i tipi di uso del suolo e le sue alterazioni e il grado di esperienza del geomorfologo coinvolto. in particolare, il riconoscimento delle caratteristiche delle frane dalle fotografie aeree in visione stereoscopica è una tecnica soggettiva, empirica e che richiede molta esperienza, pratica, metodologia e criteri di interpretazione ben definiti (malamud et al., 2004). chiaramente, i criteri basati sull’espressione superficiale di forme geomorfiche sono soggettivi; nondimeno, questo lavoro riguarda le variazioni dell’attività franosa considerate come variazione nel tempo della frequenza areale dei movimenti di massa attivi, che pertanto non devono necessariamente indicare un valore assoluto di franosità. 3.3.1 confronto tra la franosità del 1976 e del 2006 i cataloghi delle frane del 1976 (fig. 6) e del 2006 (fig. 7) sono relativi all’intero territorio comunale di rocchetta sant’antonio. in figura 8 sono sintetizzate le differenze di attività franosa. i risultati sono presentati in termini di numero di frane per km 2 e frequenza areale delle frane (percentuale dell’area occupata dalle frane sul totale dell’area) per facilitarne il confronto con altre aree franose. nel valutare le distribuzioni delle frane osservate nelle due date, si sono tenuti presenti i possibili effetti derivanti dalla differente risoluzione e modalità di elaborazione delle foto aeree e dell’immagine satellitare. l’immagine ikonos esaminata, per esempio, permette un’ottima risoluzione delle superfici di distac147 fig. 7 carta delle frane del 2006 e reticolo idrografico sovrapposti al dtm nel territorio di rocchetta. legenda: 1) frane attive nel 2006; 2) frane inattive nel 2006; 3) frane incerte nel 2006; 4) reticolo idrografico. map of 2006 landslides and hydrographic network draped over dtm (rocchetta s. antonio territory). legend: 1) active landslides in 2006; 2) inactive landslides in 2006; 3) uncertain landslides in 2006; 4) drainage network. cambiamenti dell’uso del suolo e aumento dell’attività franosa ... co e dà la possibilità di identificare in dettaglio numerose frane coalescenti laddove sulle fotografie si identifica un’unica frana. invece, alcune grandi frane inattive, identificate sulle foto aeree del 1976, non sono state riconosciute sulle immagini ikonos del 2006, non stereoscopiche. infatti, il catalogo del 2006 include una classe di frane incerte, alcune delle quali si sovrappongono alle aree con frane inattive nel catalogo relativo al 1976 (fig. 6 e fig. 7). nondimeno, le differenze nelle distribuzioni delle frane attive classificate con certezza sono pronunciate, e se ne può dedurre una variazione evidente nell’estensione areale. in particolare, il confronto tra i dati del 1976 e del 2006 mostra un incremento del 160% nella frequenza areale delle frane attive (fig. 8). una tendenza opposta si nota per le frane inattive, passando dal 7.1 all’1.6%, ed alcune delle frane inattive del 1976 risultano attive nel 2006 (fig. 6 e fig. 7). per stimare gli effetti delle due differenti metodologie di osservazione sulla stima del numero e delle aree interessate dalle frane attive, queste sono state suddivise per classi di dimensione. si nota come la distribuzione nelle classi a partire da 2000 m2 sia simile negli inventari relativi alle due date (fig. 9). al contrario si osserva come nel catalogo del 1976 sia molto ridotta la quantità di frane con estensione inferiore a 2000 m2. in particolare nel 1976 l’area interessata da frane superiori a 2000 m2 costituisce l’85% dell’area in frana complessiva, mentre scende al 65% nel catalogo del 2006 (fig. 9). ciò è coerente con la minore risoluzione e con la diversa tecnica di osservazione delle foto aeree, che rende non riconoscibili le frane di estensione minima, e individua come frana unica un insieme di piccole frane coalescenti. trascurando quest’ultimo aspetto, e assumendo quindi che la citata differenza tra le distribuzioni sia dovuta esclusivamente alla mancata osservazione di frane di piccole dimensioni nelle foto aeree del 1976, se ne ricava una sottostima del 25% dell’area in frana complessiva a quella data. tale assunzione è tuttavia assolutamente cautelativa, in quanto considera come “non osservata” l’area interessata da movimenti coalescenti di piccole estensioni che invece possono essere individuati come singolo movimento di estensione maggiore. una stima più ragionevole parte dalla constatazione della grande difficoltà, sulle foto aeree del 1976, del censimento di frane attive singole con dimensioni inferiori a 1000 m2. frane di queste dimensioni occupano complessivamente circa il 18% dell’intera area in frana nel catalogo del 2006 e solo il 3.4 % nel catalogo del 1976 148 fig. 8 statistica della franosità per il 1976 e il 2006; in alto: frequenza areale in %; in basso: numero per km2. la percentuale è riferita all’intera area di studio (72 km2); le frane incerte sono principalmente dovute alla mancanza di stereoscopia nell’immagine del 2006. landslide statistics for 1976 and 2006; upper: area frequency in %; lower: number per km2. the percentage is referred to the entire study area (72 km2); uncertain landslides are mainly due to the lack of stereoscopy in 2006 imagery. fig. 9 aree (km2) interessate dalle frane attive nel 1976 e nel 2006 suddivise per classi di estensione (m2) delle stesse. areas (km2) affected by active landsliding in 1976 and 2006 according to different size classes (m2) of landslides. c. lamanna et al. (fig. 9): ne consegue una discrepanza, dovuta alla differente metodologia di osservazione, inferiore al 15%. questo valore, non altera significativamente l’evidenza dell’aumento dell’attività franosa. infatti, assumendo per il 1976 una sottostima dell’area in frana pari al 15%, l’incremento della franosità tra il 1976 e il 2006 risulta comunque superiore al 120%. 3.3.2 distribuzione delle frane e reticolo idrografico mossa et al. (2005) studiando la franosità dell’area a nord-ovest del territorio di rocchetta sant’antonio hanno osservato che la distribuzione delle frane è strettamente connessa ai sistemi locali di drenaggio. l’interpretazione delle foto aeree del 1976 e delle immagini da satellite ikonos del 2006 forniscono le stesse indicazioni per la zona in esame in questo lavoro. infatti, considerando il modello del locale drenaggio dell’intera area di studio, estratto dalla ctr al 5000, sovrapposto alle carte inventario delle frane del 1976 e del 2006 (fig. 6, fig. 7), si osserva che le frane e il reticolo drenante sono intimamente legati sia perché spesso le frane raggiungono i corsi d’acqua (e sono erose al piede), sia perchè si attivano entro le vallecole fluviali. per fornire informazioni più oggettive sulle relazioni tra la distribuzione delle frane e i corsi d’acqua sono state condotte alcune analisi quantitative. si sono considerate quattro zone di rispetto di ampiezza crescente intorno ai corsi d’acqua: la prima tra 0 e 20 m, la seconda tra 20 e 40 m, la terza tra 40 e 80 m e l’ultima tra 80 e 160 m. quindi si sono effettuate le intersezioni delle superfici così delimitate con le frane attive e i dati sono stati espressi in termini di frequenze areali (fig. 10). si osserva che la frequenza areale delle frane attive del 1976 e del 2006 decresce con la distanza dal corso d’acqua e intorno al reticolo idrografico vi è una più alta concentrazione di movimenti franosi rispetto al valore medio sull’intero territorio comunale di rocchetta. inoltre si osserva un aumento pressocchè uniforme della frequenza areale delle frane attive dal 1976 al 2006, su tutta l’area considerata, quindi l’influenza del corso d’acqua sulle variazioni della franosità non è cambiata in maniera significativa nei trent’anni considerati. 3.4 franosità attiva e variazioni nell’uso del suolo dopo avere ricavato le mappe dell’uso del suolo relative al 1976 (fig. 11a) ed al 2006 (fig. 11b) per indicare le variazioni dell’uso del suolo nel periodo considerato, i dati mappati sono stati espressi come percentuale dell’area totale. i risultati mostrano che circa il 52% dell’area era usata come seminativo negli anni ’70 e che fino all’anno 2000 tale percentuale era cresciuta fino al 75%. un cambiamento così pronunciato dell’uso del suolo in un’area montuoso-collinare può aver avuto un impatto sulla stabilità dei pendii. i terreni alberati e l’altro, invece, sono diminuiti in estensione: per l’“altro”, vi è stato un aumento delle aree antropizzate e una diminuzione delle aree incolte. l’influenza dei cambiamenti di uso del suolo sui movimenti franosi può essere evidenziata considerando la distribuzione delle frane attive sui campi coltivati (fig. 11a e fig. 11b). un confronto visuale delle mappe del 1976 e del 2006 indica che i terreni divenuti agricoli dopo il 1976 (“nuovo seminativo”) sono caratterizzati da una maggiore densità di frane attive. per evidenziare le correlazioni tra i cambiamenti dell’estensione areale del seminativo e le variazioni delle frane attive, si sono considerati separatamente i terreni a seminativo già nel 1976 (vecchio seminativo) e quelli divenuti tali solo dopo quella data (nuovo seminativo) (fig. 12). sul vecchio e sul nuovo seminativo le frane attive si sono quasi triplicate (rispettivamente +181% e +161%); tuttavia il nuovo seminativo era più franoso già prima di essere coltivato. nel 1976 infatti, la frequenza areale delle frane in queste aree era del 2.9%, superiore anche a quella che si riscontrava sui terreni già adibiti a seminativo (1.8%). si nota anche che nello stesso periodo la frequenza di frane attive nelle restanti aree (non seminate nel 1976 e neppure oggi) è aumentata molto meno (+98%). questo suggerisce che le coltivazioni e le relative arature rendono i pendii più suscettibili alla instabilità. per comprendere meglio la più alta franosità delle aree del nuovo seminativo, l’estensione areale dei seminativi del 1976 e del 2006 è stata suddivisa per classi di pendenza (tab. 1). 149 fig. 10 frequenza areale delle frane attive del 1976 e del 2006 intorno ai corsi d’acqua e nell’intero territorio comunale di rocchetta sant’antonio. area frequency of active landsliding of 1976 and 2006 in different buffers near drainage network and in the entire municipal territory of rocchetta s. antonio. cambiamenti dell’uso del suolo e aumento dell’attività franosa ... pendenza (gradi) 0-5 5-10 10-15 15-20 20-25 > 25 area dei seminativi 1976 (km2) 4.51 22.44 9.66 0.54 0.04 0.02 area dei seminativi 2006 (km2) 6.60 29.34 15.56 2.05 0.42 0.21 tab. 1 distribuzione dei campi coltivati nel 1976 e nel 2006 in funzione della pendenza dei versanti. distribution of sown fields in 1976 and 2006 versus slope angle. 150 fig. 11 carte di uso del suolo e distribuzione delle frane attive nel territorio di rocchetta sant’antonio: a) carta del 1976 ottenuta dall’osservazione stereoscopica delle foto aeree; b) carta del 2006 ottenuta con l’utilizzo delle immagini ikonos e aster. legenda: 1) rocchetta sant’antonio; 2) terreno agricolo; 3) terreno alberato; 4) altro; 5) frane attive. land use and distribution of active landslides in the rocchetta s. antonio territory: a) 1976 map obtained through a stereoscopic interpretation of aerial photos; b) 2006 map derived from ikonos and aster imagery. legend: 1) rocchetta s. antonio; 2) sown field; 3) trees; 4) other; 5) active landslides c. lamanna et al. dalla tabella 1 si evince che la maggior parte dei campi coltivati nel 1976 e nel 2006 ricade nell’intervallo 5-10°. inoltre si osserva che i seminativi su pendenze comprese tra 5 e 10° sono aumentati del 31%, nella classe di pendenza tra 10 e 15° del 61% e oltre i 15° del 342%. appare quindi chiaro che le coltivazioni su pendenze elevate, dapprima marginali, hanno finito per riguardare porzioni significative del territorio. per approfondire ulteriormente le ragioni alla base della più alta franosità delle aree seminate dopo il 1976, si è confrontata la loro distribuzione di pendenze con quella delle aree già coltivate nel 1976 (tab. 2). i risultati mostrano che i terreni di recente coltivazione sono caratterizzati da pendenze significativamente più elevate, mentre i campi già coltivati nel 1976 mostravano pendenze più dolci. questo suggerisce che l’incremento delle frane attive sia risultato, almeno in parte, dall’estensione delle coltivazioni su terreni più ripidi e presumibilmente meno stabili. considerando la frequenza areale delle frane attive nel 1976 e nel 2006 in ciascuna classe di pendenza (tab. 3), si osserva che dal 1976 al 2006 c’è stato un aumento percentuale delle aree in frana in tutte le classi di pendenza. infine, considerando le frequenze areali delle frane attive del 1976 e del 2006 sul nuovo seminativo (tab. 4), nelle diverse classi di pendenza, si osserva un incremento generale della franosità dal 1976 al 2006. l’aumento è più alto nella classe 1015° (oltre il 180%); inoltre la più alta frequenza di frane attive (oltre il 10%) si è osservata nelle classi 10-15° e 15-20°, che includono circa la metà di tutte le aree coltivate a cereali dopo il 1976; questi versanti già nel 1976, ovvero prima di essere coltivati, erano più instabili. questo conferma il legame tra l’estensione delle coltivazioni sui versanti più ripidi e l’aumento delle frane nel 2006. 4. analisi dei dati pluviometrici dall’analisi dei dati sulla franosità e sull’uso del suolo è quindi evidente il maggiore incremento di franosità registrato sui terreni coltivati, ed in particolare l’elevata inci151 fig. 12 variazioni temporali nella frequenza areale delle frane attive (in %) per i campi coltivati e per le restanti aree. il vecchio seminativo rappresenta le aree già coltivate nel 1976, il nuovo seminativo le aree coltivate dopo il 1976, le restanti aree includono i terreni alberati e l’altro. temporal variation in area frequency of active landsliding (in %) for sown fields and remaining areas. the old sown represents areas already sown in 1976, the new sown corresponds to areas sown after 1976, and the remaining areas include arboreous land and other. cambiamenti dell’uso del suolo e aumento dell’attività franosa ... tab. 2 distribuzione delle pendenze dei terreni già coltivati nel 1976 (vecchio seminativo) e di quelle dei terreni coltivati dopo il 1976 (nuovo seminativo). area frequency statistics of slope angles for fields already sown in 1976 (old sown) and those sown after 1976 (new sown). tab. 3 frequenze areali delle frane attive nel 1976 e nel 2006 in ciascuna classe di pendenza. area frequency of active landsliding in 1976 and in 2006 for slope classes. pendenza (gradi) 0-5 5-10 10-15 15-20 20-25 > 25 distribuzione delle pendenze del 12.10 60.30 25.97 1.46 0.12 0.05 vecchio seminativo (%) distribuzione delle pendenze del 12.83 42.10 34.30 7.91 1.92 0.94 nuovo seminativo (%) pendenza (gradi) 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 >40 frequenza areale frane attive 1976 (%) 0.45 1.65 3.03 3.46 1.76 0.74 0.49 0.36 2.31 frequenza areale frane attive 2006 (%) 1.33 4.13 8.46 7.36 3.90 3.50 3.11 4.60 7.78 tab. 4 frequenza areale delle frane attive nel 1976 e nel 2006 sui campi divenuti agricoli dopo il 1976 (nuovo seminativo) nelle diverse classi di pendenza. area frequency of active landsliding in 1976 and in 2006 for slope classes of fields sown after 1976 (new sown). pendenza (gradi) 0-5 5-10 10-15 15-20 frequenza areale frane attive 1976 su nuovo seminativo (%) 0.72 2.06 4.03 5.85 frequenza areale frane attive 2006 su nuovo seminativo (%) 1.81 5.09 11.29 13.37 denza di frane sul nuovo seminativo. l’analisi delle relazioni tra franosità e uso del suolo non può tuttavia prescindere dallo studio delle precipitazioni che rappresentano nell’area di studio il principale fattore d’innesco delle frane. i dati di pioggia giornalieri disponibili per l’area di studio provengono dalla stazione pluviometrica di rocchetta sant’antonio (servizio idrografico nazionale, 1955-2006) e coprono il periodo 1955 2006. la piovosità media annua è intorno ai 670 mm (con intervallo di variabilità tra 449 e 1037 mm nei 52 anni considerati). inverno ed autunno sono le stagioni più piovose con piovosità media di, rispettivamente, 204 mm (intervallo 75-470 mm) e 195 mm (intervallo 64-360 mm), mentre l’estate è la stagione meno piovosa, con una media di 104 mm (intervallo 24-266). il mese di massima piovosità è novembre con precipitazioni medie di 79 mm, seguito da dicembre con una media di 77 mm; tuttavia, le maggiori precipitazioni mensili, nei 52 anni esaminati, si sono verificate nel mese di gennaio 2003 con 218 mm. i mesi estivi di giugno, luglio e agosto sono tipicamente molto secchi e il mese di luglio è caratterizzato dal più basso tasso di precipitazioni, in media 31 mm (fig. 13). dall’analisi dei dati è emerso che le stagioni invernali tra la fine del 2002 ed il 2006 hanno contribuito ad una fase piovosa, seguita peraltro ad un periodo di grave siccità, e nel contesto di una tendenza al calo pluviometrico sul lungo periodo (polemio & casarano, 2008). ad esempio, il trimestre invernale dicembre 2002-febbraio 2003 è stato il più piovoso in assoluto nei 52 anni considerati (360 mm). inoltre l’inverno 2005-2006, ovvero il periodo immediatamente precedente all’acquisizione dell’immagine ikonos utilizzata per il più recente inventario delle frane, è stato caratterizzato da precipitazioni ben al di sopra della media (299 mm). al contrario il periodo invernale 2001-2002 era stato tra i meno piovosi, 123 mm. altro dato importante è che il 1976 e la sua estate hanno segnato valori record di piovosità (rispettivamente 1037 e 266 mm). per di più, la maggior parte delle precipitazioni dell’estate del 1976 si sono verificate nei mesi di giugno e luglio, ovvero immediatamente prima dell’acquisizione delle foto aeree utilizzate per l’inventario delle frane del 1976. pertanto, sebbene le immagini utilizzate per i due inventari delle frane siano state acquisite in stagioni generalmente segnate da andamenti delle precipitazioni molto diversi, sia le foto aeree del 1976 sia l’immagine del 2006 sono state acquisite poco dopo periodi piovosi durati alcuni mesi, con condizioni favorevoli al dissesto (in particolare per movimenti superficiali). poichè nelle immagini analizzate si sono riconosciuti come attivi i movimenti franosi avvenuti principalmente nell’ultima stagione piovosa, sono state esaminate le quantità di precipitazioni cadute nei mesi 152 c. lamanna et al. fig. 13 a) andamento delle precipitazioni annue registrate dalla stazione di rocchetta sant’antonio dal 1955 al 2006. b) andamento delle precipitazioni medie mensili ottenute a partire dai dati giornalieri registrati dalla stazione di rocchetta sant’antonio dal 1955 al 2006. a) variation in average yearly precipitation registered in rocchetta s. antonio from 1955 to 2006. b) average monthly precipitation obtained from daily data registered in rocchetta s. antonio from 1955 to 2006. precedenti l’acquisizione delle foto aeree (luglio 1976) e delle immagini ikonos (aprile 2006). considerando il periodo (che include la stagione più piovosa) da ottobre dell’anno precedente alla data dell’acquisizione, i dati registrati sono, per il 1976 e il 2006, rispettivamente di 775 e 580 mm. considerando invece il semestre precedente all’acquisizione, si registrano ripettivamente valori di 421 e 520 mm. e’ stato inoltre effettuato, nei periodi considerati, un confronto tra i principali eventi piovosi, al fine di individuare eventuali particolarità che possano spiegare il considerevole aumento della franosità attiva individuato nelle immagini del 2006. trattandosi di frane essenzialmente superficiali, queste possono essere infatti innescate da precipitazioni di relativamente breve durata. i risultati riportati nella tabella 5 mostrano che nella stagione 1975-76 ci sono stati 5 eventi tra i 40 ed i 60 mm e 2 eventi superiori, con un massimo di 90.8 mm; nella stagione 2005-2006 ci sono stati invece 2 eventi tra i 40 e i 60 mm e 3 eventi superiori, con un massimo di 98.6 mm. la piovosità nei semestri ottobre-marzo precedenti ai cataloghi delle frane è stata valutata anche tenendo conto dell’evapotraspirazione per stimare la quantità di acqua disponibile per il deflusso e per la ricarica idrica del suolo. si è considerato il periodo ottobre-marzo perchè coincide con la stagione della ricarica in cui cioè l’evapotraspirazione potenziale è minore della piovosità media e l’evapotraspirazione potenziale coincide con quella reale. per calcolare l’evapotraspirazione potenziale media giornaliera è stata usata la formula di hargreaves samani (hargreaves & samani, 1982; 1985): ra ep = 0.0023 ––– √ –– td (t + 17.8) λ dove ep = evapotraspirazione potenziale; td = temperatura giornaliera massima meno temperatura giornaliera minima; t = temperatura giornaliera media; ra = radiazione solare extraterrestre, ovvero l’energia che incide giornalmente sulla superficie di un m2 posta orizzontalmente al di fuori dell’atmosfera, (l’effetto della copertura nuvolosa, che riduce la radiazione al suolo, è stimato attraverso l’escursione termica giornaliera); λ = calore latente di evaporazione dell’acqua. se ra è espresso in mj/m 2, per ottenere l’evaporazione in mm, λ deve essere espresso in mj/kg (1 kg/m2 = 1 mm di acqua evaporata). si è quindi calcolata la piovosità utile data dalla piovosità meno l’evapotraspirazione potenziale per i semestri ottobre-marzo dei seguenti anni: 19741975, 1975-1976, 2001-2002, 20022003, 2004-2005 e 2005-2006 (fig. 14). si osserva che la piovosità utile nel 1975-1976 e nel 2005-2006 è, rispettivamente, di circa 300 mm e 360 mm. a fronte di una quantità d’acqua disponibile per il deflusso e per la ricarica idrica del suolo di circa il 20% superiore nella stagione 2005-2006 rispetto al 1975-1976, la franosità nel 2006 risulta quasi triplicata. a tale risultato contribuisce presumibilmente anche la differente distribuzione temporale della piovosità complessiva, con un maggior numero di periodi piovosi nel 1976, ma con il 2006 caratterizzato da eventi di intensità superiore. il ruolo scatenante delle precipitazioni è confermato, in misura comunque legata alla differente azione dei fattori predisponenti, tra i quali in particolare l’uso del suolo. 5. discussione e conclusioni questo lavoro ha integrato, sfruttando le potenzialità dell’ambiente gis, dati di diverso tipo e origine. in particolare, la raccolta dei dati necessari per le carte inventario dei fenomeni franosi e per la mappatura dell’uso del suolo in diversi periodi, ha comportato sia l’indispensabile rilievo in sito, sia l’analisi di foto aeree ed immagini satellitari di diverso tipo e con differenti metodologie di trattamento. prima ancora di trarre delle conclusioni riguardanti caratteristiche e cause dell’instabilità dei versanti nell’area di studio, il lavoro suggerisce alcune valutazioni sulle tecniche e metodologie impiegate. in particolare, le immagini satellitari ad alta risoluzione, come quelle del satellite ikonos, si possono considerare una valida alternativa alle foto aeree per la realizzazione di carte 153cambiamenti dell’uso del suolo e aumento dell’attività franosa ... tab. 5 principali eventi piovosi registrati a rocchetta sant’antonio nel periodo antecedente all’acquisizione delle foto aeree del 1976 e all’acquisizione dell’immagine ikonos del 2006. main rainfall events registered in rocchetta s. antonio in the periods preceding the acquisition of 1976 airphotos and 2006 ikonos imagery. 1975-1976 12-21 ott 15-19 nov 11-13 dic 28 gen 9-11 apr 5-8 giu 29 giu-3 lug quantità (mm) 90.8 54.8 84.4 50.2 41.4 40.0 50.8 2005-2006 7-10 ott 9-13 dic 23-28 feb 10-12 mar 22-24 mar quantità (mm) 64.8 77.6 98.6 42.2 43.4 fig. 14 piovosità utile su base mensile (differenza tra piovosità ed evapotraspirazione potenziale) per i periodi ottobre-marzo precedenti l’acquisizione delle immagini usate per produrre le carte inventario delle frane. net monthly rainfall, i.e., the difference between rainfall and potential evapotranspiration for the october-march periods preceding the acquisition of the imagery used to produce landslide inventories. inventario delle frane attive ad una scala di dettaglio, permettendo di cartografare e posizionare con precisione dissesti anche di piccola estensione. fra i vantaggi dell’uso di immagini da satellite, si ha che una singola immagine ricopre grandi aree eliminando quindi la necessità di elaborare fotografie aeree multiple con i problemi collegati, come la necessità di creare mosaici di foto adiacenti a volte acquisite anche a settimane o mesi di distanza. inoltre l’uso di una singola immagine, comprendente una vasta area, riduce significativamente il volume di dati da elaborare per effettuarne l’ortorettificazione. infine, le immagini satellitari possono essere acquisite con tempi di rivisitazione inferiori a quelli necessari a ripetere una campagna aerofotogrammetrica. tuttavia, le immagini satellitari stereoscopiche ad alta risoluzione sono ancora costose rispetto alle immagini aeree e non sono state utilizzate nel presente lavoro. per consentire una visualizzazione tridimensionale le immagini satellitari si sono sovrapposte al dtm; la limitazione nell’interpretazione degli elementi distintivi morfologici dei movimenti di versante inattivi, derivante dalla mancata applicazione della modalità stereoscopica, non è stata eccessivamente penalizzante in questo studio, focalizzato sulle frane attive; tuttavia, la stereoscopia avrebbe verosimilmente permesso un riconoscimento e una mappatura più rapida dei fenomeni franosi, a parità di dettaglio. confrontando le carte inventario delle frane del 1976, del 2005 (risultante da rilievi sul campo) e del 2006 (immagine ikonos) si osserva che in molti casi i movimenti franosi tendono ad avvenire nella stessa area. ciò è in parte dovuto alla presenza di vecchi movimenti che riducono la resistenza al taglio dei materiali coinvolti lungo le superfici di rottura e sviluppano fessure nel terreno che facilitano l’infiltrazione delle acque meteoriche e la saturazione del suolo. tuttavia, il confronto tra i dati del 1976 e del 2006 mostra un deciso incremento dell’attività franosa, con un aumento del 160% della frequenza areale delle frane attive (dal 2% al 5.2%). la tendenza opposta registrata per le frane inattive (che passano dal 7.1% all’1.6%) può essere solo in parte spiegata dalle limitazioni nell’osservazione delle frane inattive dovute alla mancanza del dato stereoscopico nell’immagine ikonos; la percentuale di frane inattive nel 2006 risulta inferiore anche a causa della riattivazione di alcune frane inattive nel 1976. dai rilevamenti effettuati nell’area di studio si può affermare che l’innesco della maggior parte dei fenomeni di dissesto attivi negli ultimi anni ha seguito una serie di inverni piovosi (in particolare le stagioni 20022003 e 2005-2006). e’ quindi possibile individuare nelle precipitazioni un ruolo scatenante sull’instabilità dei pendii gia intrinsecamente “indeboliti” da altre cause. i risultati di questo lavoro mostrano che i cambiamenti dell’uso del suolo nei 30 anni considerati sono ben correlati con l’incremento della frequenza areale delle frane attive nella daunia. nel territorio di rocchetta dal 1976 al 2006 vi è stato un incremento del 46% dei seminativi (dal 52% al 75% dell’area complessiva). le zone alberate sono passate dal 9% nel 1976 al 5% nel 2006; l’allargamento delle aree adibite a seminativo è andato soprattutto a scapito dell’estensione delle aree incolte. l’impatto del cambiamento dell’uso del suolo sulla stabilità dei pendii è facilmente dimostrabile. i terreni divenuti agricoli dopo il 1976 («nuovo seminativo»), registrano un aumento della franosità del 161%, mentre quelli seminati già nel 1976 hanno registrato un incremento della franosità del 181%. tuttavia si osserva come le zone non ancora coltivate nel 1976, e invece adibite in seguito a seminativo, mostrassero già inizialmente una maggiore franosità, e che questa sia cresciuta in proporzione in conseguenza di periodi piovosi come l’inverno 2005-2006. sulle «restanti aree» (non seminate nel 1976 e neppure oggi) l’aumento della franosità dal 1976 al 2006 è stato invece del 98%, nettamente minore rispetto a quello verificatosi sui seminativi. inoltre, si è verificato che l’estensione dei seminativi è avvenuta su terreni con pendenza mediamente superiore a quella dei suoli già coltivati. se nel “vecchio seminativo” (1976) poco più del 25% si trovava su pendenze oltre i 10°, e quasi mai superiori ai 15°, il nuovo seminativo è per il 45% su pendenze oltre i 10°, e per quasi il 10% oltre i 15°. appare quindi chiaro che coltivazioni su pendenze elevate, dapprima marginali, attualmente riguardano porzioni significative del territorio. tutto ciò indica che l’incremento complessivo delle frane attive è stato favorito dall’estensione delle coltivazioni su terreni più ripidi e presumibilmente meno stabili; il «nuovo seminativo» ha occupato aree più franose già prima di essere coltivate (2.9% di area in frana contro 1.8% dei vecchi seminativi come osservato nel 1976). l’aver esteso le coltivazioni ad aree con pendenze più elevate ha ulteriormente aggravato la situazione di pendii già originariamente più instabili. in conclusione, i diffusi fenomeni di dissesto che hanno interessato l’area di studio negli ultimi anni sono stati innescati da precipitazioni superiori alla media. comunque stabilire l’impatto delle variazioni climatiche sulle frane può essere complesso se si considerano pendii modificati dall’uomo, poiché tali modifiche possono sia migliorare che peggiorare la stabilità dei pendii con una rapidità maggiore di quella dei recenti cambiamenti climatici o geomorfologici. sembra inoltre che, nell’analisi preditiva dell’impatto dei cambiamenti climatici sulla franosità, molta attenzione debba essere prestata al periodo immediatamente successivo ad ogni modificazione importante dell’assetto del pendio, sia di origine antropica (es. agricoltura intensiva) che di origine naturale (es. eventi piovosi estremi o terremoti di alta magnitudo). ci sono indicazioni che a seguito di tali modificazioni le soglie di suscettibilità al dissesto possano essere alterate significativamente rispetto a quelle basate sui precedenti dati storici di piovosità e dei dissesti associati alla piovosità stessa (ad es. wasowski, 1998; parise & wasowski, 1999). nella maggior parte dell’area di studio il numero e l’estensione dei fenomeni di dissesto sono da ricondursi a concause determinate dall’intervento antropico. la deforestazione può essere storicamente considerata come uno dei principali fattori che hanno contribuito alla franosità della daunia, così come di altre parti dell’italia meridionale (ad es. parise & wasowski, 2000). inoltre, insieme all’estensione del seminativo su pendenze elevate, seguita alle politiche europee di sostegno alla coltivazione del grano duro attuate dagli anni ’70, vanno considerate le tecniche di aratura e le modificazioni introdotte dalla pratica agricola nella gestione 154 c. lamanna et al. del reticolo idrografico lungo i versanti. le arature con i mezzi meccanici più moderni, in particolare quelli capaci di arature profonde, hanno segnato un ulteriore cambio delle caratteristiche geotecniche, ed un calo della resistenza del suolo. pertanto l’aratura sui pendii più ripidi ed in particolare le nuove arature (che hanno rimosso la vegetazione naturale esistente) che hanno come obiettivo i pendii più ripidi ancora disponibili per l’agricoltura, hanno avuto come risultato una aumentata erosione e franosità superficiale. la stabilità del territorio è stata compromessa anche dall’abbandono di opere di presidio contro l’erosione, create e faticosamente mantenute in passato da generazioni di agricoltori. la frequenza areale delle frane attive ha raggiunto, sulle aree del “nuovo seminativo” con pendenza superiore ai 10°, valori superiori all’11%. la crescita della percentuale di area in frana all’aumentare della pendenza del versante coltivato è molto rapida quando si supera la soglia dei 10°. questo suggerisce un’attenta valutazione dell’opportunità e delle eventuali modalità della pratica cerealicola su tali versanti. oltre che dal rispetto delle norme, tale valutazione non può prescindere dai costi che ricadono sulla collettività, per la messa in sicurezza e il ripristino di dissesti derivanti da un’inadeguata gestione del territorio. ringraziamenti si ringrazia l’amministrazione comunale di rocchetta sant’antonio ed in particolare il dott. a. magnotta, l’ing. g. amoruso e l’ing. g. tedeschi della regione puglia, e il dott. g. rampino per aver fornito alcuni dati usati in questo studio. inoltre si ringraziano il prof. franco loiacono e il dott. paolo giannandrea per le proficue discussioni sulla geologia locale dell’area di studio. infine siamo grati ai due referee anonimi per gli utili suggerimenti fornitici. bibliografia begueria s. 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(1994) condizioni di instabilità e rischio da frana nei comuni dell’appennino dauno pugliese geologia applicata e idrogeologia, 29: 77-141. 156 c. lamanna et al. ms. ricevuto il 10 novembre 2008 testo definitivo ricevuto il 21 aprile 2009 ms. received: november 10. 2008 final text received: april 21, 2009 imp.aprile& il ruolo dei depositi piroclastici nell’analisi cronostratigrafica dei terreni quaternari del sottosuolo della piana campana (italia meridionale ) francesco aprile1, alessandro sbrana2 & romeo m. toccaceli2 1dipartimento di scienze della terra. università di napoli “ federico ii “ 2dipartimento di scienze della terra. università di pisa riassunto: aprile f. et al., il ruolo dei depositi piroclastici nell’analisi cronostratigrafica dei terreni quaternari del sottosuolo della piana campana (italia meridionale). (it issn 0394-3356, 2004). attraverso il riesame critico delle sequenze stratigrafiche di sondaggi meccanici significativi, eseguiti nell’ambito della piana campana, correlate con i risultati di recenti studi vulcanologici, viene proposto un nuovo assetto dell’architettura del sottosuolo e ridefinita la posizione cronostratigrafica dei terreni pleistocenici ed olocenici di riempimento del bacino sedimentario e vulcanico campano. le correlazioni cronostratigrafiche tra le unità sedimentarie sono state effettuate assumendo come livelli guida le due unità da flusso piroclastico dell’ignimbrite campana (~39 ka b.p.) e dell’ignimbrite di taurano (~157 ka b.p.) datati radiometricamente, presenti sia in affioramento che nel sottosuolo della piana. ciò ha consentito di riposizionare cronologicamente i depositi marini rinvenuti in foro al disotto dell’ignimbrite di taurano al margine dei rilievi carbonatici dimostrando che la pianura campana è stata interessata da una marcata subsidenza quantomeno a partire dal tardo pleistocene medio. è stata riconosciuta l’analogia dell’assetto strutturale e stratigrafico, nel sottosuolo, tra l’area pedemontana della piana del sarno con i corrispondenti settori di nola, cicciano e cancello disposti secondo una direttrice nw-se lungo la fascia di raccordo tra la zona pianeggiante della piana campana ed i rilievi carbonatici bordieri. l’analisi geometrica della disposizione delle unità individuate nel sottosuolo ha portato al riconoscimento di un complesso piroclastico, nella parte centrale della piana, al momento non ben differenziato, di estensione e potenza significative, posizionato al tetto della ignimbrite di taurano. l’esame dei dati stratigrafici e la ricostruzione dei rapporti geometrici tra le unità, ha permesso l’allestimento di sezioni geologiche tracciate lungo direzioni significative, che forniscono un quadro inedito delle caratteristiche stratigrafiche del sottosuolo della piana campana ed un preliminare contributo alla conoscenza della evoluzione strutturale recente. abstract: aprile f. et al., the role of pyroclastic deposits in the chronostratigraphic analysis of the quaternary terrains in the subsoil of the campanian plain (southern italy). (it issn 0394-3356, 2004). the critical reinterpretation of stratigraphic data of mechanical soudings concerning the subsurface of campanian plain (southern italy) provides a new picture of the geometry and chronostratigraphic position of the quaternary deposits filling the sedimentary basin of this plain. the radiometrically dated ignimbrite deposits, of campanian ignimbrite (~39 ka b.p) and taurano ignimbrite (~157 ka b.p), have been considered as levels guide in carrying out the correlations between the lithological units. this has allowed the singling out of marine sediments, previuously not well considered, underlaying the taurano ignimbrite indicating that the campanian plain underwent subsidence even prior to upper pleistocene. the structural and stratigraphic analogy, in the subsurface, among the sarno’s area with the corresponding sectors of nola, cicciano and cancello located along the carbonatic reliefs, bordering the plain to nw-se direction, has also been recognized. finally a pyroclastic deposit at present not well differentiated, topographically localized in the central area of the plain, to the top of taurano ignimbrite, has been recognized. the re-examination of the stratigraphical sequences, picked in more significant sections, provides a new frame of the subsurface characteristics of the campanian plain and a preliminary contribution for the knowledge of the recent structural evolution. parole chiave: piana campana; tefra; ignimbriti;pleistocene superiore e medio; depositi marini. keywords: campanian plain; tephra; ignimbrites; upper and middle pleistocene; marine deposits, boreholes. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 547-554 la piana campana: assetto schematico geologico-strutturale e vulcanologico l’evoluzione geologico-strutturale della piana campana e le relazioni con il vulcanismo quaternario sono state oggetto di una vasta messe di lavori scientifici (ippolito et al., 1973; aprile & ortolani, 1978; finetti & morelli, 1974; brancaccio et al .,1991; cassano & la torre, 1987; bruno et al.,1998). da questi risulta che la piana si è impostata fisiograficamente in un graben peritirrenico – di età plio-pleistocenica – esteso dal monte massico all’alto strutturale della penisola sorrentina e governato da sistemi di faglie dirette, con notevoli rigetti, sia in direzione appenninica che antiappenninica. al suo interno, favorita anche da fenomeni subsidenti, si è verificata una intensa aggradazione sedimentaria che ne ha determinato il parziale colmamento (fig. 1) anche la stratigrafia del sottosuolo della piana è stata indagata da vari autori (aprile & ortolani,1985; cinque et al., 1991; romano et al., 1994; barra et al., 1996; aprile & toccaceli, 2002) che hanno accertato la presenza di varie unità stratigrafiche, marine, continentali, transizionali e vulcaniche a partire dal pleistocene all’attuale. la mancanza di sedimenti marini pliocenici nelle sequenze stratigrafiche dei pozzi profondi perforati nella piana del volturno (ippolito et al., 1973) e trecase1, al margine sud-orientali del somma-vesuvio, (brocchini et al., 2001), induce inoltre a concludere che la piana sia rimasta in ambiente continentale durante tale epoca (brancaccio et al., 1991; cinque et al., 1993), 548 f. aprile, a. sbrana & r.m. toccaceli conoscendo, in seguito, una marcata subsidenza a partire, quantomeno, dal tardo pleistocene medio (aprile & toccaceli, 2002), se non addirittura dal plio-pleistocene (ietto & sgrosso, 1963), e fasi trasgressive fino all’olocene. brocchini et al., (2001), sulla base di una revisione critica dei dati del pozzo trecase 1, ritengono che l’area vesuviana abbia subito una subsidenza, rispetto al livello di base attuale, di circa 40 metri negli ultimi 37 ka. cinque (1991), per contro, riporta limitatamente alla piana del sarno (costituente, a sud del somma vesuvio, il prolungamento, della piana campana in s.s) un valore di circa 30 metri negli ultimi 130 ka . particolarmente numerosi risultano gli studi sulla storia vulcanica della piana campana; molti di questi sono mirati alla comprensione della genesi della ignimbrite campana (ic), il deposito ignimbritico trachitico che con i suoi 150-300 km3 di volume (rosi & sbrana, 1987; orsi et al., 1999 ; rolandi et al., 2003) costituisce la formazione vulcanica più largamente rapfig. 1 schema geologico della piana campana: 1 sedimenti alluvionali e vulcanoclastici quaternari. 2 complesso vulcanico del somma-vesuvio. 3 complessi vulcanici dei campi flegrei, procida e ischia. 4 complesso vulcanico del roccamonfina. 5 unità terrigene mioceniche e plioceniche. 6 unità carbonatiche mesozoiche. 7 principali elementi tettonici. geological scheme of the campanian plain: 1 alluvial and volcanoclastic quaternary sediments. 2 -somma-vesuvius volcanic complex. 3 phlegrean fields, procida and ischia volcanic complexes. 4 roccamonfina volcanic complex. 5 -miocene and pliocene terrigeneous sedimentary rocks. 6 -principal tectonic elements. presentata nella regione. l'area sorgente della ignimbrite campana viene posizionata da alcuni autori nell’area calderica flegrea (rosi & sbrana,1987; fisher et al., 1993; orsi et al.,1999), o nella cosiddetta “fossa di acerra” a ne di napoli (scandone et al.,1991), altri autori ne ipotizzano l’origine da una o più eruzioni fissurali posizionate lungo preesistenti linee tettoniche con direzione ne-sw, nwse e e-w associate all’evoluzione della catena appenninica (di girolamo,1968; 1970; 1978; di girolamo et al., 1984; barberi et al., 1978; lirer et al., 1987; de vivo et al., 2001; rolandi et al., 2003). de vivo et al., (2001) hanno individuato e datato radiometricamente altri prodotti piroclastici – sia in affioramento che nel sottosuolo della piana campana – di età più antica della ic spostando all’indietro fino ad oltre 300 ka b.p l’inizio dell’attività vulcanica nella piana. brocchini et al., (2001) invece, ritengono che a partire da 400-300 ka b.p e fino alla emissione della ic non esistano evidenze di attività vulcanica nella parte vesuviana della piana. bellucci et al., (2003) segnalano, in corrispondenza del margine orientale dei monti di caserta, al letto della ic, la presenza di depositi da flusso piroclastico prevalentemente pomicei (pumice flow) non litoidi, da essi correlati alla formazione di durazzano (~116 ka b.p). de vivo et al., (2003) oltre a ritenere che la formazione della ic sia in realtà costituita da due unità sovrapposte corrispondenti a due distinti eventi ignimbritici compresi in uno stretto intervallo temporale, ritengono che la storia vulcanica della piana campana comprenda la deposizione di varie coltri ignimbritiche di cui 3 – ben differenziate litologicamente e rappresentate rispettivamente dall’ignimbrite di seiano (~ 289÷245 ka b. p), dall’ignimbrite di taurano (~ 157 ka b.p) e da quella di durazzano (~116 ka b.p) – sono precedenti alla deposizione della ic. i tefra della piana campana come metodologia per le correlazioni crono stratigrafiche delle unità sedimentarie quaternarie del sottosuolo le ignimbriti trachitiche, datate radiometricamente, presenti nella piana campana sia in affioramento che nel sottosuolo,costituiscono preziosi livelli guida (narcisi, 1994) per la determinazione cronostratigrafica delle altre unità sedimentarie, di varia facies litologica, ad essi intercalati. recenti studi vulcanologici (de vivo et al., 2001) oltre a datare la ic (39.29 ± 0.11 ka b.p.), hanno individuato lungo i rilievi bordieri della piana del sarno un altro deposito da flusso piroclastico, in facies di tufo giallo litoide, sottostante la ic, da essi denominato ignimbrite di taurano (it) datato a 157.4 ± 1.00 ka b.p. tale unità si presenta in affioramento con caratteristiche petrografiche e stratigrafiche tipiche così riassumibili ( de vivo et al., 2003): a) aspetto e consistenza di tufo giallo litoide; b) spessore non inferiore ai 6 metri ; c) stratigraficamente si posiziona su un livello di pomici e ceneri dello spessore di circa 1.5 m e risulta sottoposta ad un paleosuolo di circa 0.7 m a sua volta sottogiacente a circa 1 m delle cosiddette “pomici basali” della ic; il tutto è ricoperto dalla ic in facies di tufo grigio campano. nel sottosuolo, in settori significativi, ai fini della 549il ruolo dei depositi piroclastici ... ricostruzione dell’assetto stratigrafico e strutturale della piana proposto nel presente lavoro, al di sotto della ic, si individua una unità tufacea gialla litoide di spessore variabile, ma sempre superiore ai 6 – 8 metri, correlabile, anche in base ad analogie geometriche e stratigrafiche con gli affioramenti segnalati (de vivo et al., 2003), con la ignimbrite di taurano. tale formazione è stata quindi assunta come marker di riferimento per riposizionare cronostratigraficamente i depositi marini rinvenuti al suo letto; infatti, aprile & toccaceli (2002), sulla scorta di tali dati e di quelli desunti da sondaggi profondi ubicati lungo la fascia pedemontana della piana di sarno al raccordo con i rilievi carbonatici bordieri (nicotera & civita, 1969), hanno individuato nel sottosuolo, al di sotto dell’ignimbrite di taurano, depositi di spiaggia attribuibili quantomeno al tardo pleistocene medio, spostando quindi all’indietro – rispetto al pleistocene superiore, come finora ritenuto – l’attività subsidente del settore di piana campana posto a se del complesso sommavesuvio. discussione dei dati e correlazioni stratigrafiche per lo svolgimento della presente ricerca sono stati reperiti presso enti e società specializzate alcune centinaia di stratigrafie relative a sondaggi meccanici, di profondità significative, realizzati nella piana campana negli ultimi 50 anni ( fig.2) per svariate finalità; su tali dati è stata poi eseguita una rigorosa e minuziosa attività di omogeneizzazione stratigrafica ,di analisi di facies e di ricostruzione dei rapporti geometrici tra le varie unità piroclastiche e sedimentarie riconosciute. particolare attenzione è stata posta nel riconoscimento della it dalle altre due formazioni ignimbritiche pre ic (ignimbriti di durazzano e di seiano) riscontrate nell’area campana (de vivo et al., 2003); del resto, come precedentemente esposto, le caratteristiche litologico-stratigrafiche tipiche della it la rendono individuabile, con relativa facilità, anche nei sondaggi meccanici. la formazione di durazzano, infatti si presenta come un pumice flow mai litoide (bellucci et al., 2003 ; de vivo et al., 2003) di spessore intorno ai due metri mentre quella di seiano, risulta caratterizzata (de vivo et al., 2003) dalla sovrapposizione di 3 distinti depositi di flusso piroclastico di colore rossastro e più o meno alterati. le analisi condotte, alla luce delle nuove conoscenze vulcanologiche, ed il riassetto delle geometrie tra le unità individuate per il sottosuolo campano, hanno consentito l’allestimento di una serie di sezioni geologiche significative (fig. 3) che evidenziano un quadro dell’architettura geologica quaternaria del sottosuolo della piana campana legata all’evoluzione recente. la verifica e comparazione dei dati ottenuti, per l’intero sviluppo della piana campana, ha permesso di individuare tre principali settori (settori a, b, c1, c2) disposti parallelamente alla linea di costa (fig. 4). lungo direttrici longitudinali e trasversali a questi è stato inoltre individuato anche un comportamento differenziato nell’ambito della recente evoluzione tettonica. settore a): nel sottosuolo, lungo la fascia di raccordo con i rilievi carbonatici che bordano in direzione 550 ne la piana campana, da sarno a cancello, risultano presenti condizioni stratigrafiche e strutturali simili. infatti, a parte la presenza del substrato mesozoico carbonatico, il motivo stratigrafico ricorrente è caratterizzato dalla presenza e sovrapposizione stratigrafica lungo tutta la direttrice sarno-cancello di due depositi di flusso piroclastico correlati (de vivo et al., 2001; aprile & toccaceli, 2002), dall’alto verso il basso stratigrafico, con la ic (~39 ka b.p.) nella facies del tufo grigio campano e con l’ignimbrite di taurano (~157 ka b.p.) in facies di tufo giallo litoide. per quanto riguarda la morfologia del tetto della ic se ne riscontra una graduale immersione, procedendo verso il centro della piana, tale andamento non sembra essere dovuto a cause tettoniche, ma alla preesistente morfologia su cui si è adagiata, sebbene a luoghi, in affioramento, si osservano brusche soluzioni di continuità nell’unità ignimbritica che possono indurre a ritenere la presenza di faglie. anche il tetto dell’ignimbrite di taurano, oltre a tracce di erosione in ambiente continentale, presenta uno sviluppo progressivamente degradante sia verso sw che verso nw, in direzione del volturno, che ne determina lo sprofondamento e la scomparsa nei sondaggi; tale strutturazione risulta presumibilmente causata dalle fasi tettoniche post 157 ka b.p. comune, lungo tutto questo settore, è inoltre il rinvenimento, al di sotto della ignimbrite di taurano, di depositi marini la cui età risulta evidentefig. 2 ubicazione dei sondaggi meccanici. tracce delle sezioni geologiche location of boreholes. cross-sections marks f. aprile, a. sbrana & r.m. toccaceli fig. 3 sezioni geologiche schematiche: 1 depositi di spiaggia ed eolici (attuale – recente); 2 depositi alluvionali e piroclastici subaeree (in posto e/o rimaneggiate) flegree e vesuviane (attuale – olocene); 3 tufo giallo del gauro (circa 10,5 ka b.p.); 4 tufo giallo napoletano (circa 12 ka b.p.); 5 depositi alluvionali e transizionali (lagunari e palustri) del “complesso versiliano”; 6 depositi di spiaggia e litorali del “complesso versiliano”; 7 piroclastici e lave dell’edificio vulcanico del sommavesuvio (olocene); 8 depositi alluvionali e piroclastici in posto o rimaneggiate post ic (olocene – tardo pleistocene superiore); 9 lave del monte somma (tardo pleistocene superiore); 10 ignimbrite campana (circa 39 ka b.p.).; 11 depositi marini del tardo pleistocene superiore; 12 depositi alluvionali e di conoide di “scanzano” (pleistocene superiore); 13 depositi marini del pleistocene superiore; 14 depositi alluvionali e di conoide di “gragnano” (pleistocene superiore); 15 complesso piroclastico indifferenziato (tardo pleistocene medio – pleistocene superiore); 16 ignimbrite di taurano (circa 157 ka b.p.); 17 depositi alluvionali, lacustri e piroclastici rimaneggiate (tardo pleistocene medio – pleistocene superiore); 18 depositi marini e di spiaggia del tardo pleistocene medio – pleistocene medio (?); 19 termini calcareo-dolomitici mesozoico-terziari; 20 faglia certa; 21 faglia presunta. schematical geological sections: 1 present beach and eolian recent deposits; 2 alluvial deposits and subaerial pyroclastic products (in situ or reworked) of plhegrean fields and somma-vesuvius volcanic complex (olocene); 3 “gauro” yellow tuff (about 10,5 ky b.p.); 4 neapolitan yellow tuff (about 12 ky b.p.); 5. alluvial, palustrine and lagoonal deposits of the “versilian complex”; 6 beach and shore sediments (with peat levels) of the “versilian complex”; 7 lavas and pyroclastic products of somma-vesuvius complex (olocene); 8 alluvial deposits and subaerial pyroclastic products (in situ or reworked) post-cgt (olocene – late upper pleistocene); 9 monte somma lavas (late upper pleistocene); 10 campanian grey tuff (about 39 ky b.p.); 11 beach and marine deposits (late upper pleistocene); 12 “scanzano” alluvial fan deposits (upper pleistocene); 13 marine deposits (upper pleistocene); 14 “gragnano”alluvial fan deposits and recent alluvial or debris cones deposits (upper pleistocene); 15 indifferenziated volcanoclastic complex (late middle pleistoene – upper plesitocene); 16 taurano yellow tuff (about 157 ky b.p.); 17 alluvial, lacustrine and pyroclastic deposits (late middle pleistoene – upper plesitocene).; 18 beach and marine deposits (late middle pleistocene); 19 dolomites and limestones (cenozoic – mesozoic).; 20 certain fault; 21 presumed fault. 551il ruolo dei depositi piroclastici ... 552 mente più antica di 157 ka b.p. e quanto meno attribuibili ad un tardo pleistocene medio (aprile & toccaceli, 2002); tale attribuzione cronologica risulta essere compatibile con quanto riportato da altri autori (ietto & sgrosso,1963) che segnalano la presenza di depositi marini terrazzati, in corrispondenza del versante meridionale dei rilievi più occidentali della dorsale di avella, di età plio-pleistocenica inferiore, correlandoli con le argille quaternarie poste a varia profondità nel sottosuolo della piana del sarno e nei dintorni di maddaloni. l’assetto cronostratigrafico ricostruito fa assumere a questi sedimenti marini il ruolo di una vera e propria unità guida e di riferimento che consente di ritenere che la subsidenza nella pianura campana sia stata attiva, in questo settore, quanto meno dal tardo pleistocene medio – se non addirittura dal plio-pleistocene – e non solo nel pleistocene superiore come finora ritenuto (brancaccio et al., 1991; cinque,1991; romano et al., 1994). settore b): costantemente presente nel sottosuolo o, talora affiorante, lungo tutto questo settore è la presenza della ic, generalmente nella facies di tufo grigio campano, il cui tetto tende ad approfondirsi procedendo verso la costa; a luoghi risulta mancante ma ciò non ne esclude la presenza a profondità maggiore di quella raggiunta con i sondaggi; del resto cassano & la torre (1987), in base ai risultati geofisici, prolungano la presenza del tufo grigio campano fino alla linea di costa. lungo questa fascia centrale della piana, al letto della ic si rinviene un deposito, costituito da un’alternanza di prodotti piroclastici incoerenti, al momento non meglio classificati nel contesto cronostratigrafico del sottosuolo della piana, sebbene, nel tratto pomigliano d’arco marigliano, le geometrie ricostruite consentono di posizionarlo al tetto della ignimbrite di taurano da cui se ne differenzia anche litologicamente; tale constatazione porta quindi a ritenere che tali prodotti siano comunque compresi nell’intervallo temporale 157-39 ka b.p. questa unità vulcanica, per le caratteristiche cronostratigrafiche e geometriche individuate può, in generale, interfacciarsi con i sedimenti del pleistocene superiore, e correlarsi, quindi, per alcuni casi particolari, con l’unità che romano et al., (1994) posizionano al di sopra dei sedimenti tirreniani nella piana del volturno. cronologicamente la presenza di fig. 4 suddivisione schematica dei settori a, b, c1 e c2. schematical subdivision sectors a, b, c1 and c2). f. aprile, a. sbrana & r.m. toccaceli questo deposito contraddice ulteriormente la tesi avanzata da brocchini et al., (2001) che escludono attività vulcanica nella zona vesuviana della piana precedenti alla messa in posto della ic. il mancato rinvenimento in questo settore della ignimbrite di taurano tranne che probabilmente per una piccola estensione lungo il citato tratto pomigliano d’arco-marigliano in corrispondenza di analoghe profondità di sondaggio nel settore a), si ritiene addebitabile, come già affermato in precedenza, ad una attività tettonica post ignimbrite di taurano che ne ha determinato il dislocamento in profondità al passaggio tra i due settori. settori c1) e c2): nella parte più settentrionale del settore c1 risulta ampiamente rappresentata la formazione del tufo grigio campano sia in affioramento (lungo il versante meridionale del mt. massico e verso i rilievi bordieri verso caserta), che nel sottosuolo, per poi scomparire in corrispondenza del graben della foce del volturno per motivi tettonici e/o spinti processi erosivi; è possibile il rinvenimento di lembi relitti così come ricostruito con i sondaggi lungo la sezione 1 di figura 4, nei pressi del canale agnena. nella zona costiera, prossima al lago patria e alla foce di licola il tetto del tufo grigio si presenta con dislocazioni di varia entità per gli effetti di una tettonica post 39 ka b.p. (aprile et al.,1992). lungo alcuni settori costieri, al di sotto del tufo grigio campano si rinvengono, così come accertato da barra et al., (1996), anche depositi marini correlati con la risalita glacioeustatica interstadiale dello stage isotopico 3. per quanto concerne il settore c2 l’andamento del tufo grigio campano è particolarmente articolato; difatti, procedendo parallelamente alla linea di costa, se ne constata la scomparsa sia in corrispondenza del fosso di volla che alla foce del sarno, anche in questo caso, per cause tettoniche e spinti processi di erosione, per poi riapparire, al sotto dell’edificio vulcanico del somma vesuvio ove il suo letto si ritrova alla profondità di circa –120 metri al sotto del livello marino attuale (brocchini et al., 2001; aprile & toccaceli, 2002). conclusioni l’analisi dei dati stratigrafici provenienti dai sondaggi meccanici finora disponibili e la rielaborazione critica degli stessi alla luce delle nuove conoscenze vulcanologiche, unitamente alla applicazione di una rigorosa ricostruzione dell’assetto geometrico-strutturale delle unità riconosciute nella definizione complessiva dell’architettura del sottosuolo della piana campana per profondità significative, consentono di affermare quanto segue: e’ stata riconosciuta una prima analogia stratigraficostrutturale, nel sottosuolo, lungo la direttrice sarnocicciano-nola-cancello lungo la fascia pedemontana di raccordo tra il margine interno della piana campana ed i rilievi cartonatici bordieri. viene confermata, quindi, la presenza, al di sotto della ignimbrite campana, di un'altra unità piroclastica, in facies di tufo giallo litoide, costantemente presente nel sottosuolo, correlabile con l’ignimbrite di taurano (~ 157 ka b.p). le analisi che sono state condotte su tutta l’area hanno infine permesso di verificare altre analogie in ambiti sempre più prossimi alla linea di costa attuale procedendo dai rilievi carbonatici bordieri secondo una direzione ne-sw. tali analogie e la relativa discriminazione nel contesto stratigrafico-strutturale complessivo, hanno consentito di individuare una serie di settori (a, b, c1, c2) disposti secondo una direzione nw-se (appenninica) che evidenziano caratteri evolutivi differenziati; ciò non toglie che anche lungo lo sviluppo dei singoli settori siano presenti condizioni stratigrafiche e strutturali tali da definire una differenziazione in direzione nw-se. a partire dai rilievi bordieri e procedendo verso il centro della piana l’unità più antica rinvenuta nei sondaggi, risulta essere costituita da sedimenti marini quanto meno attribuibili al tardo pleistocene medio o anche più antichi se si considera la presenza di sedimenti marini del tardo plio-pleistocene rinvenuti da altri autori lungo la dorsale di avella. la ricostruzione cronostratigrafica eseguita per questo settore di pianura porta a ritenere che la piana campana sia stata interessata da subsidenza già a partire dal tardo pleistocene medio, se non prima, e non solo nel pleistocene superiore come finora ritenuto. i depositi marini rinvenuti al di sotto della ignimbrite di taurano, assumono, quindi, il ruolo di una vera e propria unità di riferimento utile per la correlazione cronostratigrafica dei sedimenti che si rinvengono a letto e a tetto; tale unità, procedendo progressivamente verso la linea di costa, già a partire dai settori centrali della piana campana, non viene più rinvenuta nei sondaggi, ed in ogni caso, alle medesime profondità riscontrate lungo il settore pedemontano, verosimilmente, per gli effetti connessi con una tettonica post 157 ka b.p. in nessuno dei settori considerati sono stati rinvenuti, nel sottosuolo, depositi da flusso piroclastico aventi tipologia tale da essere attribuiti alle altre due ignimbriti pre ic (ignimbriti di durazzano e di seiano), la cui presenza quindi, allo stato attuale della ricerca, rimane circoscritta sul versante orientale dei monti di caserta e nel vallone di seiano in penisola sorrentina rispettivamente. vengono confermati gli effetti sulla ignimbrite campana di una tettonica post 39 ka b.p. che determina dislocamenti del tetto di varia entità, particolarmente evidenti lungo la fascia più prossima alla costa (zona del lago patria, foce di licola, foce sarno, complesso del somma-vesuvio). viene identificata nel sottosuolo dei settori centrali della piana campana, una unità vulcanica, la cui posizione stratigrafica, relativamente alle ignimbriti campana e di taurano, ne definisce una collocazione cronostratigrafica nell’intervallo 157-39 ka b.p. la stessa, procedendo verso la linea di costa, si interfaccia, in modo ancora non chiarito definitivamente, con i sedimenti marini del pleistocene superiore. tali constatazioni inducono a correlare l’unità appena descritta con quelle vulcaniche flegree pre-ignimbrite campana che affiorano estesamente nei settori non collassati dei campi flegrei, nell'area urbana di napoli, dei camaldoli, di monte di procida , cuma etc. allo stato attuale della ricerca, tuttora in corso, si constata che l’evoluzione recente della piana campana è stata caratterizzata , procedendo da ne verso sw, da marcati e talora differenziati fenomeni di subsidenza. 553il ruolo dei depositi piroclastici ... lavori citati aprile f. & ortolani f. 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(1991) the structure of the campanian plain and the activity of the neapolitan volcanoes (italy). j. volcanol. geotherm. res. 48,1-31. 554 ms. ricevuto il 21 maggio 2004 testo definitivo ricevuto il 2 novembre 2004 ms. received: may 21, 2004 final text received: november 2, 2004. f. aprile, a. sbrana & r.m. toccaceli base burial dating of late-cenozoic deposits using in-situ produced cosmogenic nuclides 1andrea ciampalini, 2cristina persano, 2derek fabel, 1marco firpo 1dipartimento per lo studio del territorio e delle sue risorse, genova 2department of geographical and earth science, university of glasgow corresponding author: a. ciampalini <andrea.ciampalini@dipteris.unige.it> riassunto: ciampalini a. et al. calcolo dell’età di seppellimento di depositi tardo-cenozoici attraverso gli isotopi cosmogenici. (it issn 0394-3356, 2010) la datazione di depositi fluvio-deltizi neogenico-quaternari è spesso difficile a causa della mancanza, al loro interno, di biomarkers stratigrafici. definire un intervallo temporale preciso in cui è avvenuta la deposizione dei sedimenti che si ha intenzione di analizzare risulta fondamentale in molti campi della geologia, geomorfologia, stratigrafia e geoarcheologia. lo studio di questi depositi è fondamentale per comprendere l’evoluzione del paesaggio in termini di erosione, incisione fluviale e tassi di deposizione in conseguenza di attività tettonica o cambiamenti climatici. le tecniche di datazione tradizionali o più utilizzate come la termoluminescenza o il 14c su materiale organico hanno un limite temporale piuttosto ristretto e risultano inutilizzabili in caso di sedimenti più vecchi del pleistocene superiore. per sedimenti più vecchi e/o in mancanza di sostanze organiche, gli isotopi cosmogenici trovano una più vasta applicabilità, non solo per la datazione dei sedimenti, ma anche in numerosi altri settori della geologia. verrà di seguito illustrata la procedura di preparazione dei campioni e la teoria del metodo degli isotopi cosmogenici, evidenziando le caratteristiche necessarie per applicare il metodo e illustrando la versatilità dello stesso per risolvere problematiche molto differenti fra loro. abstract: ciampalini a. et al. burial dating of late-cenozoic deposits using in-situ produced cosmogenic nuclides. (it issn 03943356, 2010) dating the miocene to pleistocene deposition of fluvial and deltaic sediments is often difficult because of the absence of suitable biostratigraphic markers. temporal limits on sediment deposition, however, are fundamental constraints in many geological, geomorphological, stratigraphical and archeological studies. in particular a dated stratigraphy of sedimentary basins provides information about timing of evolution of the sediment source and routing system due to tectonics, sea-level and/or climate changes. traditional techniques, such as luminescence, radiocarbon dating of organic material, etc. only permit us to date sediments that are no older than ~250,000 years. recently a method for dating sediment burial using the radioactive decay of cosmogenic nuclides 26al and 10be has been developed. 26al and 10be are produced by the continuous bombarding by high-energy cosmic rays of the earth surface where they penetrate into rocks and sediments at a depth that varies, depending on rock density, between 2 and 3 m. the long half-life of the 26al (7.05x105 yr) and 10be (1.5x106 yr) make them optimal for dating sediments that were deposited over the past five million years, as long as the sediments were at the surface and exposed to cosmic rays before sedimentation and burial. the sediments that can be dated using the cosmogenic isotopes technique need to have the following characteristics: (1) quartz needs to be present and have been exposed at the surface for a time necessary to accumulate measurable cosmogenic radionuclides concentration (i.e., depending on latitude and altitude, at least ~ 200 years); (2) transport time needs to have been negligible (3) burial was rapid and deep (>10 m) to avoid cosmogenic nuclides production after deposition, otherwise a correction needs to be introduced. this method is useful in many italian areas where deltaic or fluvial miocene to pleistocene deposits crop out. parole chiave: nuclidi cosmogenici; età di seppellimento; tassi di erosione; età di esposizione; raggi cosmici. keywords: cosmogenic nuclides; burial dating; erosion rates; exposure age; cosmic rays. il quaternario italian journal of quaternary sciences 23(1), 2010 125-136 1. introduzione l’utilizzo dei nuclidi cosmogenici terrestri è legato alla misurazione della concentrazione di tali isotopi che si sono accumulati nelle rocce o nei sedimenti a causa dell’interazione fra la radiazione cosmica e la superficie terrestre. davis & schaffer nel 1955 furono i primi ad utilizzare i nuclidi cosmogenici terrestri (nct) prodotti nei minerali che si trovano sulla superficie terrestre per risolvere problematiche connesse alla geologia. prima di allora erano stati analizzati solamente campioni provenienti da meteoriti e dalla superficie lunare (reedy et al., 1983). le tecniche che i ricercatori avevano a disposizione per misurare le concentrazioni dei nuclidi cosmogenici non permettevano ancora di poter analizzare campioni terrestri in quanto, in questi ultimi, la concentrazione di tali nuclidi era troppo bassa per la risoluzione degli strumenti di allora. le piccole concentrazioni di nuclidi cosmogenici presenti nelle rocce terrestri divennero misurabili a partire dai primi anni ’80 con lo sviluppo di tecnologie più avanzate: l’acceleratore di massa (ams) e lo spettrometro di massa convenzionale per i gas nobili. da allora sono state sviluppate due principali metodologie che prevedono l’utilizzo dei nct. la prima prevede la datazione di superfici esposte mentre la seconda permette di determinare i tassi di erosione o meglio il tempo necessario per erodere una superficie di ~1-2 metri di spessore. recentemente è stata sviluppata una terza applicazione che, sfruttando il diverso tasso di produzione e decadimento dei radionuclidi, permette di datare l’età di seppellimento di una superficie, sia essa costituita da roccia o sedimenti (granger & muzikar, 2001). la datazione di superfici esposte è stata la prima applicazione (e.g. davis & 126 a. ciampalini et al. schaffer) ed è ancora oggi la metodologia più utilizzata. in realtà il concetto di nuclidi cosmogenici terrestri risale al 1912 quando hess formulò una propria teoria che riguardava il comportamento dei raggi cosmici. questa teoria venne ripresa nel 1934 da grosse il quale osservò che quando i raggi cosmici raggiungevano la superficie terrestre scatenavano delle reazioni fisiche che davano origine a nuclidi cosmogenici che chiamò elementi radio-cosmici. nel 1949 libby realizzò che era possibile misurare la quantità di 14c prodotta dall’interazione tra i raggi cosmici e l’atmosfera. nel 1955 davis & schaffer datarono l’età di esposizione di una superficie in roccia nelle montagne rocciose abbandonata dal ritiro del ghiacciaio dopo l’ultimo glaciale, misurando la concentrazione del 36cl. a partire dal 1960, alcuni studi di fisica illustrarono come i raggi cosmici interagissero con il campo magnetico terrestre e con l’atmosfera, evidenziando come il tasso di produzione dei nuclidi cosmogenici variasse al variare della quota e della latitudine. infine negli anni ’70 vennero analizzati campioni di meteorite e lunari di cui abbiamo accennato sopra (reedy et al., 1983). poiché la concentrazione dei nuclidi cosmogenici nelle rocce e nei sedimenti è di diversi ordini di grandezza inferiore che nell’atmosfera, è stato necessario attendere l’introduzione dell’ams e dello spettrometro di massa convenzionale per i gas nobili per poterla misurare. grazie a questi strumenti è stato possibile calcolare i tassi isotopici con un errore inferiore al 3%. inoltre l’ams è capace di rilevare rapporti isotopici di 10be, 26al, 14c, 36cl e 129i aventi rapporti atomici con il corrispettivo isotopo stabile dell’elemento in questione dell’ordine di 10-10 e 10-16. lo spettrometro per i gas nobili consente di raggiungere la stessa precisione con il 21ne, ma le quantità minime da analizzare sono molto maggiori. dal 1985 i lavori che riportano analisi isotopiche utilizzando i nct sono aumentati considerevolmente. 2. applicabilita’ del metodo oggi l’impiego di queste metodologie è molto diffuso in tutto il mondo. per esempio i nct sono stati impiegati per ricostruire le variazioni volumetriche dei ghiacci durante il quaternario, datando le superfici di esarazione dei ghiacciai e i depositi morenici continentali (nishiizumi et al., 1991a; gosse et al., 1995a; ivyochs et al., 1995; ackert et al., 1999; zreda et al., 1999) e montani (phillips et al., 1990; gosse et al., 1995b; jackson et al., 1997; moscariello et al., 1998; fabel et al., 2006; yingkui et al., 2008). i nct sono stati utilizzati per datare eventi vulcanici (marti & craig, 1987; phillips et al., 1986; cerling, 1990; nishiizumi et al., 1990; anthony & poths, 1992; licciardi et al., 1999), eventi paleo-sismici (bierman & gillespie, 1994; gosse et al., 1996; ayarbe et al., 1998; zreda & noeller, 1998), tassi di uplift di rocce, di superfici e tassi di incisione (brook et al., 1995; seidl et al., 1997; gosse et al., 1997; leland et al., 1998; barnard et al., 2001; pratt et al., 2002; matsushi et al., 2006; kober et al., 2007). queste metodologie si sono rivelate utili anche per datare eventi o oggetti particolari come i vetri del deserto libico (klein et al., 1986) o il momento dell’impatto del meteorite che ha originato il cratere del canion diablo (nishiizumi et al., 1991b; phillips et al., 1991). l’applicabilità degli isotopi cosmogenici per la datazione di sedimenti spazia dai depositi morenici ai massi erratici, ai block streams (phillips et al., 1990; brown et al., 1991; phillips et al., 1996; 1997; miller et al., 2002; bowen et al., 2002; wilson et al., 2008) ai terrazzi fluviali con annessi depositi (molnar et al., 1994; repka et al., 1997; schaller et al., 2002), agli alluvial fan e debris flow (cerling, 1990; ritz et al., 1995; liu et al., 1996; regard et al., 2006), ai depositi costieri lacustri (trull et al., 1995; balco & schaefer, 2006), fino ai depositi costieri marini (perg et al., 2001). nel campo della geologia strutturale i nct possono essere utili per datare superfici di faglia, tassi di movimento e la ricorrenza di eventi sismici (zreda & noeller, 1998; mitchell et al., 2001; jackson et al., 2002). la datazione di eventi franosi è un altro aspetto della geomorfologia che può essere risolto utilizzando i nct (ballantyne et al., 1998; kubik et al., 1998; barnard et al., 2001). inoltre è possibile anche datare piattaforme di abrasione marina (stone et al., 1996; alvarez-marrón et al., 2008), calcolare i tassi di erosione superficiale di rocce, regoliti e superfici deposizionali (cockburn et al., 1999; summerfield et al., 1999) e tassi di erosione superficiale a scala regionale (riebe et al., 2000; schaller et al., 2001; nichols et al., 2002). utilizzando i nct è possibile calcolare i tassi di movimento verticale e/o orizzontale di materiale nei suoli (heimsath et al., 1999; 2000; phillips, 2000), nelle lateriti (brown et al., 1998; braucher et al., 2000; schoreder et al., 2001), nei depositi di versante (small et al., 1999; heimsath et al., 2002), nei depositi eolici (klein et al., 1986; shepard et al., 1995) e in ambiente desertico (shepard et al., 1995; wells et al., 1995). recentemente i nct sono stati utilizzati anche per datare eventi di seppellimento di superfici, materiali e sedimenti permettendo, quindi, la datazione di depositi molto vecchi, fino a circa cinque milioni di anni (granger & muzikar, 2001; granger et al., 2001; balco & rovey, 2008; ciampalini et al., 2009). 3. teoria del metodo i raggi cosmici vengono originati da diverse sorgenti come il sole, le altre stelle, le stelle a neutroni, i buchi neri, i nuclei galattici attivi e le galassie radio. nella nostra galassia, tali raggi sono prodotti prevalentemente in seguito ad esplosioni di super-novae e, dopo aver attraversato i campi magnetici interplanetari e terrestri, interagiscono con l’atmosfera terrestre. questa interazione produce una cascata di particelle che reagiscono a contatto con l’atmosfera e con la superficie terrestre. l’interazione fra i raggi cosmici ad alta energia e l’atmosfera terrestre da origine alla formazione di raggi cosmici secondari, fra cui neutroni e muoni. il tasso di produzione dei nuclidi cosmogenici è dipendente dal flusso di raggi cosmici il quale, a sua volta, è fortemente influenzato dal campo magnetico terrestre ed è attenuato dall’atmosfera terrestre (lal & peters, 1967; dunai, 2000; 2001; stone, 2000; gosse & phillips 2001). l’influenza del campo magnetico e dell’atmosfera terrestre sono la causa della traiettoria seguita dai raggi cosmici e, quindi, del diverso tasso di produzione a seconda della latitudine e altitudine. infatti il tasso di produzione dei nuclidi cosmogenici è elevato alle alte latitudini, perché i raggi cosmici primari vengono deviati maggiormente all’equatore rispetto ai poli ed è maggiore ad alta quota perché lo spessore di atmosfera attraversato dal flusso dei raggi cosmici secondari è minore. il tasso di produzione è influenzato anche dalla geometria e dalla morfologia del sito di campionamento, in quanto la presenza di montagne circostanti o di una superficie fortemente inclinata possono essere causa di schermatura della superficie che si intende andare ad analizzare. le problematiche appena esposte trovano comunque soluzione nell’applicazione di fattori di correzione che tengono presente della latitudine, altitudine (lal, 1991; stone, 2000), dell’inclinazione della superficie e del profilo dell’orizzonte (dunne et al., 1999). i neutroni generati durante l’interazione fra i raggi cosmici e l’atmosfera o la superficie terrestre possono penetrare per alcuni metri nelle rocce e nei sedimenti (la profondità dipende dalla densità del materiale attraversato). i muoni, invece, possono penetrare per kilometri sotto la superficie terrestre. l’interazione nucleare fra neutroni e muoni con i minerali presenti nelle rocce (quarzo, k-feldspato, olivina, calcite, etc.) produce nuclidi cosmogenici (3he, 10be, 14c, 21ne, 26al e 36cl). esistono tre diversi meccanismi attraverso cui i nuclidi cosmogenici vengono prodotti: spallazione dei neutroni, azione dei muoni lenti e azione dei muoni veloci (gosse & phillips, 2001). nei primi tre metri della crosta terrestre il meccanismo della spallazione è dominante, mentre diventa subordinata agli altri due meccanismi procedendo in profondità. la spallazione avviene quando un neutrone collide con un nucleo bersaglio (templeton, 1953) e separa da esso alcune particelle, lasciando un nucleo più leggero (es. il 28si contenuto nel quarzo si trasforma in 21ne). i muoni risultano dal decadimento di mesoni instabili che vengono prodotti dall’interazione dei raggi cosmici primari con l’atmosfera. la produzione di isotopi cosmogenici attraverso i muoni lenti avviene attraverso reazioni di cattura di muoni negativi, mentre i muoni veloci danno luogo ad una cascata di particelle che, per esempio, producono 26al e 10be anche in profondità (granger & muzikar, 2001). la radiazione derivante dai raggi cosmici è rilevante in quanto determina il tasso di produzione dei nuclidi cosmogenici nelle rocce o nei sedimenti esposti (gosse & phillips, 2001) (tab.1). le incertezze di circa il 10% (20% per il 21ne) sul tasso di produzione degli isotopi cosmogenici derivano da una serie di fattori; in particolare dal fatto che la variazione temporale del flusso di radiazioni cosmiche non è conosciuta con accuratezza. per diminuire tali incertezze si misurano, per ogni campione, due isotopi cosmogenici e se ne considera il rapporto. poiché per un dato campione di roccia o sedimento tutte le variabili che contribuiscono a determinare il tasso di produzione dei nuclidi cosmogenici sono le stesse e influiscono sui vari isotopi nello stesso modo, il rapporto fra due nuclidi cosmogenici è solo influenzato da incertezze analitiche, che di solito non superano il 3%. dal punto di vista del campionamento, la presenza di una superficie orizzontale piatta ad alte latitudini e sul livello del mare rappresenta la condizione ideale per misurare il tasso di produzione dei nuclidi cosmogenici. in ogni altro caso, i tassi di produzione elencati in tabella 1 devono essere corretti per tenere conto della latitudine, altitudine e esposizione del campione ai raggi cosmici (lal, 1991; stone, 2000). simili correzioni devono essere apportate anche ai sedimenti per ricavarne l’età di deposizione (granger & muzikar, 2001). 127burial dating of late-cenozoic deposits ... 4. preparazione del campione la preparazione del campione per la misurazione delle concentrazioni degli isotopi cosmogenici risulta piuttosto lunga e laboriosa. l’obiettivo finale è quello di isolare i nuclidi da analizzare da tutto il resto del campione. viene presentata di seguito la procedura utilizzata per l’estrazione dell’26al e del 10be dal quarzo utilizzata attualmente presso i laboratori dell’università di glasgow e dello scottish universities environmental research centre di east kilbride (uk). la procedura è sostanzialmente composta da due parti, la prima (fig. 1) consiste nella purificazione del campione, ovvero si cerca di isolare il minerale contenente i nuclidi cosmogenici (es. quarzo). la seconda parte (fig. 2) prevede l’estrazione dal quarzo dei nuclidi di cui si vuole misurare la concentrazione. data la loro affinità chimica, l’26al e il 10be si estraggono dal quarzo con la stessa procedura, mentre ogni altro nuclide richiede un approccio diverso. per estrarre l’26al e il 10be da un campione di roccia o di sedimento è necessario, prima di tutto, trattare il campione fino a ridurlo a puro quarzo. altri nuclidi cosmogenici possono essere utilizzati nel caso il quarzo non sia presente; per esempio si può determinare la concentrazione di 36cl in carbonati o di 3he in pirosseni e olivina. dal quarzo è possibile estrarre anche il 21ne. i passaggi per ottenere un campione di quarzo purificato sono numerosi e, non sempre tutti necessari; dipendono dalla purezza iniziale del campione. estrarre quarzo puro da un conglomerato costituito da clasti di quarzo richiede un lavoro minore rispetto, per esempio, ad un campione di micascisto. la separazione del quarzo inizia con la frantumazione del campione, che viene in seguito setacciato con due setacci aventi luce di 250 µm e 500µm al fine di tripartirlo in tre classi granulometriche distinte (>500µm, 250÷500 µm e <250 µm). la classe granulometrica utilizzata per proseguire la procedura è quella centrale. la classe granulometricamente più fine viene scartata, mentre la più grossolana viene conservata come scorta fino alla fine della procedura. le prime fasi ad essere allontanate sono costituite dai carbonati e dai minerali magnetici. i carbonati vengono lisciviati ponendo il campione in una soluzione 1:3 di 10%hcl e hno3 a 90°c per circa 12 ore. questa lisciviazione allontana completamente i carbonati e parte dei minerali magnetici. si procede poi con l’eliminazione dei feldspati e delle miche, utilizzando una particolare procedura che prende il nome di “froth floatation” (letteralmente “galleggiamento della schiuma”). affinché questo metodo dia buoni risultati, il campione deve essere precedentemente immerso per 1 ora in una soluzione di acido fluoridrico all’1%. l’impiego dell’acido fluoridrico cambia il chimismo della superficie dei granuli di feldspato / mica e del quarzo, rendendo i primi idrofobi e il secondo idrofilo. dopo un’ora l’hf viene eliminato e il campione viene immerso in una soluzione di 10 l di acqua a cui si aggiungono 1 ml di acido acetico e 1 g di laurilammina per ogni litro di acqua, alcune gocce di olio di pino o di eucalipto. l’acido acetico mantiene il ph della soluzione intorno a 5 per agevolare la dissoluzione dei feldspati ad opera della laurilammina. l’olio di pino o di eucalipto servono per mantenere unite le bolle di co2 nella soluzione carbonatica che tenderanno a rimanere in alto (come la schiuma della birra). i feldspati e le miche resi idrofobi 128 dall’hf si vanno a concentrare nella schiuma e quindi sono facilmente rimovibili. la procedura viene ripetuta più volte fino ad eliminare tutto il materiale idrofobo. quello che rimane è costituito solamente da quarzo e minerali pesanti. dopo aver asciugato il campione si procede all’eliminazione della restante parte dei minerali magnetici facendo passare il campione precedentemente lisciviato in un separatore magnetico. esso è costituito da un magnete che genera un campo magnetico di 1.2 ma utile ad estrarre i minerali magnetici sopravvissuti alla lisciviazione. al fine di eliminare gli allumino-silicati rimasti si pongono 40 g di campione in 400 ml di acido orto-fosforico all’85% a 240°c per circa 1 ora. gli allumino-silicati si legano fra loro formando una gelatina che deve essere dissolta e rimossa inserendo nel beaker dell’idrossido di sodio. si ritiene che tutti questi passaggi portino alla perdita di circa il 10% del quarzo presente nel campione iniziale, soprattutto se la granulometria dei cristalli è inferiore a 250 µm; per questo motivo il campione iniziale deve essere particolarmente ricco in quarzo. silicati ancora presenti nel campione dopo il trattamento con l’acido fosforico vengono dissolti immergendo il campione in hf diluito al 2% per 72 ore in una vasca ultrasonica. la maggior parte dei minerali silicatici si dissolve più velocemente del quarzo in hf diluito, quindi possono essere corrosi e facilmente asportati lasciando un campione residuo ricco in quarzo. la lisciviazione con hf ha il grande vantaggio di dissolvere anche la parte più esterna dei granuli di quarzo ed eventuali fratture dove si concentrano le contaminazioni di 10be meteorico. il processo viene ripetuto almeno tre volte, rinnovando ogni volta la soluzione a base di hf. alcuni minerali non vengono dissolti, come i minerali accessori (zircone, rutilo, ilmenite) che comunque non causano problemi per la successiva estrazione dell’al e be, il granato e la muscovite che è sopravvissuta alla froth floatation. la purezza del separato così ottenuto viene quantificata attraverso la misurazione della concentrazione dell’al nel campione. essa deve essere più bassa possibile, preferibilmente compresa fra 10÷100 ppm. una concentrazione più alta può essere sintomo della presenza di inquinanti (0,5% di feldspato corrisponde a circa 1000 ppm di al). una volta purificato il quarzo si procedere alla separazione dell’al e del be che vengono poi analizzati con l’ams usando la procedura della diluzione isotopica. questo metodo consiste nell’aggiungere al campione una quantità nota (spike) di un isotopo dello stesso elemento (9be e 27al); lo spettrometro misura i rapporti 9be/10be e 27al/26al da cui si può facilmente risalire alle quantità di 26al e 10be presenti nel campione. la tecnica della diluzione isotopica ha svariati vantaggi, sia analitici, poiché le misurazioni di rapporti sono in genere più precise ed accurate rispetto a misurazioni di concentrazioni assolute, sia metodologici, dal momento che, una volta che campione e spike sono in equilibrio nella soluzione, un’eventuale perdita parziale del campione non ha ripercussioni sull’analisi. una volta aggiunto il 9be e, se la concentrazione di al nel campione è <1000 ppm, l’27al, si procede con la “digestione” del campione in hf. il quarzo viene lasciato in hf concentrato a circa 100°c per il tempo necessario alla sua completa dissoluzione (1-5 giorni). la diluzione isotopica richiede la conoscenza della quantità di spike aggiunta con la massima precisione e accuratezza possibile. ciò si ottiene prelevando una piccola quantità (di solito circa 5 a. ciampalini et al. fig. 1 schema illustrante la prima parte della procedura di preparazione del campione (purificazione del quarzo). diagram showing the quartz cleaning procedure. 129 ml) dalla soluzione di hf contenente il quarzo dissolto. la soluzione prelevata viene trattata con h2so4 e hno3 e analizzata con l’icp-ms che fornisce la concentrazione nella soluzione dello spike. la soluzione di hf rimasta servirà per l’estrazione del be e dell’al. essa viene fatta evaporare completamente per eliminare i fluoruri tossici; sul fondo del beaker rimane una patina costituita da fe, ti, al, be, etc. che deve essere di nuovo disciolta per eliminare le impurità utilizzando la tecnica dello scambio ionico. la dissoluzione della patina viene eseguita aggiungendo 2 ml di 6n hcl. l’aggiunta avviene sulla piastra a 120°c perché la soluzione deve evaporare di nuovo. l’operazione viene ripetuta tre volte per consentire la perfetta dissoluzione della patina. alla fine della terza volta la soluzione non viene fatta evaporare ma viene posta in un tubo da centrifuga con altri 2 ml di 6n hcl. il tubo viene centrifugato per 10 minuti a 3500 rpm. lo scambio ionico avviene in due parti: lo scambio anionico e lo scambio cationico. la prima parte prevede che la colonna utilizzata per la separazione venga in parte riempita con una resina anionica (ag1 x8 200-400#) condizionata con 1,2m hcl e 6n hcl. una volta che gli acidi sono stati filtrati completamente attraverso la resina si versa il campione nella colonna. la parte di campione filtrata viene raccolta poiché contiene l’al e il be, mentre il fe e il ti sono stati catturati dalla resina. non tutto il ti viene catturato in questa parte della procedura, per cui il campione viene fatto evaporare fino a far rimanere soltanto una patina che viene trasformata in solfato aggiungendo al campione essiccato acqua pura con tracce di 0,5m h2so4 e fatta evaporare di nuovo. l’operazione viene ripetuta per tre volte consecutive. l’ultima volta l’evaporazione non viene effettuata. a questo punto il campione è pronto per lo scambio cationico per eliminare il ti rimasto e per separare il be dall’al. la procedura è simile a quella effettuata per lo scambio anionico ma utilizzando una resina cationica (ag 50w-x8 200-400#) che viene cariburial dating of late-cenozoic deposits ... fig. 2 schema illustrante la seconda parte della procedura di preparazione del campione (estrazione di al e be). diagram showing the extraction procedure of al and be. 130 cata nella colonna. la resina viene condizionata con 4m hcl, 1,2m hcl e 0,2m h2so4 prima di inserire il campione nella colonna. in questo caso l’al e il be vengono trattenuti dalla resina, mentre ciò che esce dalla colonna è acido contenente il ti. il be viene eluito dalla resina utilizzando 1,2n hcl e l’al con 4m hcl. la soluzione contenente be viene fatta evaporare fino a far rimanere una patina che verrà di nuovo disciolta in 2ml di 1%hno3. la soluzione viene portata a ph 4 usando 10%-20% nh4oh per precipitare l’eventuale ti che, in tal modo, viene eliminato. il ph viene successivamente aumentato fino ad 8 per permettere la precipitazione del be. la soluzione viene centrifugata in modo che il be precipitato si concentri alla base della provetta in modo da poter eliminare la parte liquida. il be viene essiccato in forno a 70°c. la stessa procedura viene seguita per far precipitare l’al. al e be vengono trasferiti in piccoli contenitori per essere posti nella fornace a 800°c per la completa deidratazione. a questo punto il campione è pronto per essere inserito nei catodi. il be viene mescolato con del nb, mentre l’al viene mescolato con ag per esaltare il segnale nell’ams. le miscele ottenute vengono inserite in appositi catodi e inviate all’ams per la misurazione dei rapporti isotopici. 5. interpretazione del dato il tasso di produzione del 10be e 26al nel quarzo esposto alla superficie terrestre è dovuto principalmente all’azione dei neutroni, mentre la produzione dei muoni è subordinata di molte grandezze. al contrario, in profondità, la componente dovuta ai muoni diviene dominante. la produzione dovuta ai neutroni è funzione della profondità ed è facilmente calcolabile attraverso la seguente equazione (lal, 1991; brown et al., 1992): (1) dove pn è il tasso di produzione dell’isotopo cosmogenico dovuto all’interazione con i neutroni (n), z è la profondità sotto la superficie e l0 prende il nome di lunghezza di attenuazione nucleonica ed è uguale a 160/ρ cm (reedy et al., 1994), dove ρ è la densità del materiale attraversato dai raggi cosmici (in g/cm3) e 160 (g/cm2) è la lunghezza di attenuazione per i neutroni veloci nel quarzo. la produzione dovuta ai muoni è anch’essa dipendente dalla profondità, ma non è facilmente modellizzabile con una equazione semplice. essa è rappresentabile con la somma di tre termini esponenziali (granger & smith, 2000; granger & muzikar, 2001): (2) dove p1 e p2 sono costanti legate alla produzione dei muoni lenti (0,096 e 0,021 per il be e 0,723 e 0,156 per l’al), p3 è una costante legata alla produzione da parte dei muoni veloci (0,026 per il be e 0,192 per l’al) e l1, l2 e l3 rappresentano le lunghezze di attenuazione nucleoniche relative ai muoni (738/ρ cm, 2688/ρ cm, 4360/ρ cm). la produzione dovuta ai muoni, in alcuni casi specifici e in particolare quando si calcolano età di esposizione, può essere trascurabile. in situazioni in cui la superficie è caratterizzata da tassi di erosione compresi fra 1m/ma e 10m/ma o dove i clasti non sono stati sepolti sufficientemente, ignorare la produzione dovuta ai muoni può significare incorrere in un errore nella valutazione del calcolo dei tassi di erosione o dell’età del seppellimento (granger & muzikar, 2001). 5.1 datazione di una superficie esposta e calcolo del tasso di erosione. la datazione dell’esposizione di una superficie è una delle applicazioni più comuni del metodo di datazione con i nct, poiché la concentrazione di nuclidi cosmogenici nelle rocce esposte è dipendente dal tempo durante il quale la superficie è rimasta esposta ai raggi cosmici. i risultati migliori sono stati ottenuti datando superfici che vengono esposte da eventi discreti come per esempio eruzioni vulcaniche, frane, superfici di faglia e superfici di esarazione di ghiacciai. si hanno condizioni ideali quando la superficie considerata ha subito una storia poco articolata (nessuna erosione o seppellimento dalla prima esposizione). in questo caso la concentrazione alla superficie dei radionuclidi, n(0), calcolata in funzione del tempo è la seguente (lal, 1991): (3) mentre per i nuclidi stabili è data da: (4) dove p(0) è il tasso di produzione alla superficie, λ è la costante di decadimento e t è il tempo di esposizione (fig. 3). il limite temporale superiore del metodo di datazione dipende sostanzialmente dal radionuclide utilizzato ed è determinato dalla costante di decadimento del radionuclide stesso (circa 4-5 volte il tempo di dimezzamento). la lunghezza di attenuazione considerata per il calcolo del tasso di produzione dei nct è piuttosto piccola. nelle rocce terrestri e lunari è compresa tipicamente fra 121 fino a valori poco maggiori di 170 gcm-2 (gosse & phillips, 2001). le equazioni (3) e (4) possono essere utilizzate solo quando la superficie esposta non ha subito erosione. le superfici che vengono erose risultano impoverite in nct, quindi la concentrazione misurata risulta più bassa di quella che si sarebbe potuta misurare in caso di non erosione. di conseguenza, se si misurasse un’età di esposizione, si tratterebbe di una età più giovane di quella reale. se la superficie è in erosione, la concentrazione degli isotopi cosmogenici può essere utilizzata per calcolare il tasso di erosione attraverso la seguente equazione: (5) dove ninh è la concentrazione ereditata da un eventuale periodo di esposizione precedente a quello che si va a considerare ed ε è il tasso di erosione. questa equazioa. ciampalini et al. ne assume che i nct siano solo prodotti dai neutroni, un’assunzione valida per tassi di erosione maggiori di 10m/ma o minori di 1m/ma (granger & muzikar, 2001). nel caso di tassi di erosione compresi fra questi due valori è necessario utilizzare una equazione più complessa che tenga conto anche della componente muonica nel tasso di produzione. l’equazione (5) ha due incognite, il tempo di esposizione t e il tasso di erosione ε e quindi, come tale, non può essere risolta a meno che una delle due incognite sia in altro modo conosciuta. per esempio, se si assume ε = zero, l’equazione (5) si riduce all’equazione (3) e il tempo di esposizione può essere calcolato. nel caso in cui il tasso di erosione sia diverso da zero, l’equazione (5) può essere risolta solo nel caso in cui l’erosione sia in condizioni di stato stazionario, cioè rimanga constante nel tempo e nello spazio (lal, 1991). in questo caso, infatti, il tasso di erosione può essere rappresentato come la velocità con cui una particella di roccia si avvicina alla superficie; se la velocità è constante (stato stazionario), la concentrazione di un isotopo cosmogenico, per esempio il 10be, fornisce il tasso di erosione. questo metodo da risultati migliori per tassi di erosione inferiori ai ~5 m/ma (lal, 1991). alti tassi di erosione possono essere calcolati utilizzando due isotopi, per esempio 26al e 10be; in questo caso si otterrà un sistema di due equazioni a due incognite (equazione 5) e quindi risolvibile. la concentrazione di due nct permette di calcolare il tasso di erosione, il tempo minimo di esposizione di una superficie e il tempo di seppellimento di superfici o sedimenti. nel quarzo l’26al viene prodotto ad una velocità circa sei volte superiore rispetto al 10be, ma decade ad una velocità doppia. il rapporto 26al/10be al momento in cui un campione raggiunge la superficie ha un valore pari a 6,9 (utilizzando i tassi di produzione della tab.1). 131burial dating of late-cenozoic deposits ... fig. 3 andamento della concentrazione dei radionuclide 10be, 26al, 21ne e del rapporto 26al/10be con il passare del tempo. la situazione si riferisce a misurazioni effettuate nel quarzo esposto su una superficie orizzontale, non schermata e non sottoposta ad erosione. le curve sono state ottenute utilizzando le equazioni (3) e (4) ed il tasso di produzione ad alte latitudini e sul livello del mare. variation of the concentrations of the radionuclides 10be, 26al, and the stable nuclide 21ne and of the ratio 26al/10be with time in quartz exposed at the surface of a flat, unshielded, non-eroding outcrop.the values are calculated using equation (3) and (4) using sea level, high latitude production rates. fig. 4 in questo grafico viene messa in relazione la concentrazione del 10be con il rapporto 26al/10be. i campioni prelevati da superfici continuamente esposte cadono sulla curva che unisce i cerchietti vuoti. i campioni prelevati da superfici sottoposte a erosione in condizioni di stato stazionario cadono, invece, sulla curva inferiore che unisce i cerchietti neri. le curve intermedie che uniscono quelle appena descritte mostrano l’andamento dei campioni per un determinato tasso di erosione. l’area compresa fra le due curve principali prende il nome di “isola dell’erosione allo stato stazionario” (lal, 1991). se i campioni hanno una storia evolutiva dal punto di vista dell’esposizione semplice e si assume che il tasso di erosione sia rimasto costante nel tempo allora essi cadranno all’interno dell’isola. i campioni che cadono al di sotto dell’isola hanno avuto una storia più complessa che può aver compreso periodi di seppellimento o erosione non allo stato stazionario (fabel, 2008). plot of 10be concentration vs. 26al/10be (also referred to as "banana-plot"). continuously exposed samples fall on the curve connecting the open circles. steadily eroding samples lie on the lower curve connecting the solid dots. the finest curves show the trajectory of samples within the 10be concentration vs. 26al/10be space for the given steady-state erosion rates. the area bounded by the continuous exposure and steady-state erosion curves is known as the "steady-state erosion island" (lal, 1991). given a simple exposure history and assuming production rate ratios have remained the same through time, all samples collected on the surface of the earth must lie within the steady-state erosion island. samples that lie below the steady-state erosion island have experienced a complex history, which may include burial, or non-steady state erosion in the sample's recent history (fabel, 2008). tab.1 caratteristiche dei principali isotopi cosmogenici trattati in questo lavoro. i tassi di produzione sono stati determinati e calibrati in località poste ad alte latitudini (>60°), sul livello del mare e su campioni già datati con altre metodologie (l al, 1991; s tone et al ., 1998; d unai, 2000; 2001; niedermann, 2000; stone, 2000). characteristics of the major in-situ produced cosmogenic nuclides in terrestrial materials cited in this work. production rates have been calculated and calibrated at high latitudes (>60°), at sea level and in samples already dated with other methods lal, 1991; stone et al., 1998; dunai, 2000; 2001; niedermann, 2000; stone, 2000). aumentando il tempo di esposizione il rapporto 26al/10be tenderà a decrescere a causa della maggiore velocità di decadimento dell’26al, fino al raggiungimento dell’equilibrio secolare (fig. 4). in caso di superfici soggette ad erosione, l’equilibrio secolare viene raggiunto per valori di 26al/10be più alti. 5.2 calcolo dell’età di seppellimento il calcolo dell’età di seppellimento richiede, come per l’età di esposizione, il rispetto di alcuni vincoli. il primo prevede che il sedimento campionato sia stato esposto per un periodo di tempo sufficientemente lungo da acquisire una quantità misurabile di nuclidi cosmogenici prima del seppellimento. successivamente il sedimento eroso dal versante deve essere sepolto rapidamente in modo che sia schermato dai raggi cosmici e la produzione di nuovi nuclidi cosmogenici cessi definitivamente. l’età di seppellimento può essere calcolata solo misurando la concentrazione di due nuclidi, per esempio 26al e 10be. dal momento del seppellimento il rapporto 26al/10be inizia a decrescere seguendo un andamento ben conosciuto attraverso il quale è possibile risalire all’età di seppellimento che spesso corrisponde all’età di deposizione. questo metodo è ottimo, ad esempio, per datare sedimenti che si sono deposti in grotte, in sistemi deltizi di fiumi con aste fluviali piuttosto brevi o paleosuoli sepolti. utilizzando l’26al e il 10be l’equazione di granger & muzikar (2001) fornisce il tempo di seppellimento: (6) (7) dove tburial è l’età di seppellimento e (n26)i e (n10)i rappresentano rispettivamente il numero iniziale di atomi dell’26al e 10be. poiché l’26al decade più velocemente del 10be il tasso n26/n10 decresce in maniera esponenziale rispetto al tempo: (8) le incognite in questo caso sono 3: tburial, (n26)i e (n10)i. risolvendo contemporaneamente le equazioni (6), (7) e (8) e utilizzando il grafico di figura 5 è possibile ricavare l’età del seppellimento e il tasso di erosione che caratterizzava i versanti subito prima del seppellimento (granger et al., 1997; granger et al., 2001). il calcolo dell’età di seppellimento è utilizzabile per datare depositi che hanno un’età compresa fra 100.000 anni e 5 milioni di anni. il limite dei 100.000 anni è dovuto essenzialmente all’errore sperimentale. ciò deriva dall’incertezza nella misurazione del tasso 26al/10be, stimata nell’ordine del 5% che si traduce in una incertezza nel calcolo dell’età di circa 96.000 anni (granger & muzikar, 2001). il limite dei 5 milioni di anni è dovuto al tempo che i nuclidi impiegano a raggiungere il proprio equilibrio secolare. maggiore è il tempo di seppellimento, maggiori saranno le difficoltà nel misurare le concentrazioni di 26al e 10be nel sedimento stesso perché le concentrazioni diminuiscono. l’assenza di nuclidi cosmogenici nel deposito analizzato può avere diversi significati: (1) il tempo di seppellimento è maggiore di 5 milioni di anni per cui gli isotopi instabili sono completamente decaduti o (2) il periodo di esposizione ai raggi cosmici pre-seppellimento è stato talmente breve da non rendere possibile la formazione di nuclidi cosmogenici. e’ impossibile determinare quale delle due opzioni sia esatta senza disporre di ulteriori informazioni. nel caso in cui il tempo di seppellimento sia maggiore di 5 milioni di anni è teoricamente possibile utilizzare al posto dell’26al il 21ne, un isotopo cosmogenico stabile la cui concentrazione rimane costante una volta che il sedimento è stato sepolto. la possibilità di utilizzare il rapporto 10be/21ne per datare sedimenti pliocenici è ancora agli albori e non esistono ancora studi che abbiano applicato questa promettente metodologia. 132 a. ciampalini et al. fig. 5 grafico utilizzato per calcolare l’età di seppellimento di sedimento o di superfici in roccia utilizzando la concentrazione del 10be vs. il tasso 26al/10be. i campioni che non hanno subito seppellimento cadranno nella zona fra le curve indicate nel grafico con steady-state erosion e continuous exposure che corrisponde all’isola della figura 4. i campioni che hanno subito seppellimento e sono rimasti schermati dai raggi cosmici seguiranno le linee parallele alla linea che indica il normale decadimento radioattivo (radioactive decay time). il rapporto misurato 26al/10be determina l’età di seppellimento e può essere utilizzato per determinare anche il tasso di erosione attivo al momento della deposizione del sedimento (fabel, 2008). burial dating plot showing the 10be concentration and 26al/10be ratio in sediment or rock. quartz with no burial history should plot between the steady erosion and continuous exposure curves (fig.4). for quartz that is buried and completely shielded from cosmic rays, the 26al/10be decreases along a line parallel to the solid "radioactive decay time". the measured 26al/10be ratio in a sample determines the burial time, and can also be used to calculate the pre-burial erosion rate (fabel, 2008). 6. conclusione i nct sono uno strumento estremamente interessante ed utile per comprendere e studiare sia l’evoluzione e la storia della superficie terrestre sia per analizzare le velocità dei processi geologici e geomorfologici. questa metodologia sta velocemente integrando le tecniche di datazione classiche, soprattutto in campo geomorfologico e sta iniziando a dare un importante contributo anche in campo stratigrafico. i nct vengono utilizzati per datare forme e depositi (morene glaciali, terrazzi fluviali, depositi lacustri e marini costieri, depositi alluvionali, etc.) al fine di effettuare ricostruzioni paleoambientali e paleoclimatologiche. in geologia strutturale vengono impiegati per datare piani di faglie. in geomorfologia sono impiegati in maniera estensiva per studiare in modo quantitativo le variazioni del paesaggio nel tempo a diversa scala, dal singolo affioramento al bacino idrografico completo. lo studio della stratigrafia e dell’evoluzione del paesaggio durante il plio-pleistocene sono due aspetti che richiedono necessariamente l’utilizzo di metodi di datazione. purtroppo i metodi classici (es. biostratigrafia, palinologia) non sono spesso utilizzabili in quanto sono legati alla presenza di particolari organismi all’interno dei sedimenti e, comunque, non sono utilizzabili per datare le forme del paesaggio. altri metodi, come il 14c o gli osl, sono, invece, applicabili soltanto per datare sedimenti piuttosto giovani. in questo panorama l’utilizzo degli isotopi cosmogenici si inserisce con successo in quanto risulta applicabile in situazioni molto diverse fra loro. esso inoltre non si limita a restituire una datazione ma fornisce anche informazioni aggiuntive come, ad esempio, il tasso di erosione che era presente al momento della deposizione di un sedimento o che ha generato una forma. l’ampia utilizzazione del metodo è dovuta al fatto che gli isotopi cosmogenici sono legati ai minerali in cui si formano. in particolar modo l’26al e il 10be si formano nel quarzo il quale ha un’ampia diffusione nella crosta terrestre. uno dei vantaggi del metodo risiede anche nell’ampiezza dell’intervallo temporale in cui è applicabile. tale intervallo è legato al tempo di decadimento degli isotopi da analizzare e, quindi, permette di datare sedimenti o forme vecchie fino a circa 5 milioni anni fa. la validità del metodo è confermata anche dalla crescente presenza di questo tipo di analisi nelle pubblicazioni legate alle tematiche del quaternario. il calcolo dell’età di seppellimento, in particolare, risulterebbe di particolare interesse per ottenere delle datazioni assolute nelle successioni stratigrafiche della penisola italiana. in questo caso è necessario ricordare che il calcolo dell’età di seppellimento utilizzando gli isotopi 26al e 10be richiede il rispetto di condizioni ben definite che ne limitano l’uso a sedimenti di età compresa fra il messiniano e il pleistocene superiore a causa dell’incertezza nella misurazione. inoltre la possibilità di applicare questa metodologia è legata anche a fattori fisici e geologici come la necessaria presenza di quarzo nel sedimento, la presenza di depositi che abbiano acquisito un set di nuclidi cosmogenici prima della loro erosione e un seppellimento veloce dopo un breve trasporto. per questo i depositi deltizi legati ad un reticolo idrografico poco sviluppato o i depositi di grotta rappresentano delle condizioni ideali per datare i sedimenti utilizzando gli isotopi cosmogenici. bibliografia ackert r.p., barclay d.j., borns h.w., calkin p.e., kurz m.d., steig e.j., fastook j.l. 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ciencias naturales, csic, madrid (spain) corresponding author: a.m.f. valli <andrea_vallifr@yahoo.fr> abstract: microwear patterns of twenty seven points on the enamel surface of a fossil horse tooth (upper p3-4; equus altidens granatensis, late early pleistocene, barranco leon 5, guadix-baza basin, spain) were analysed by a correspondence analysis test with the dual aim of testing the suitability of this premolar in analysing microwear of horses, and of analysing how consistent the microwear patterns are across different micro-areas on a single cheek tooth. the results obtained stress that remarkable differences in dental scars are restricted to few zones. the microwear patterns of the lingual enamel surface of the paracone, the point classically analysed on upper m2 for studying microwear in ruminants, and of the pli caballin are the most consistent with those of the other analysed micro-areas. the pattern of dental microwear shown at these points by the upper p3-4 of equus altidens granatensis from barranco leon 5 is closer to those shown by seasonal mixed feeders than of those by strict grazers. keywords: equidae, guadix-baza basin, late early pleistocene, microwear analysis, spain. 1. introduction analysis of dental wear, particularly the microscopic marks produced during chewing on occlusal enamel surfaces, both by tooth/food (abrasion) and tooth/tooth (attrition) interaction, is among the most significant tools applied by palaeontologists to infer dietary behaviour and the environmental context of extinct herbivore mammals. during the last forty years studies on this subject studies have more and more enhanced and new methodological approaches have continuously been developing (e.g. gordon, 1984; teaford, 1986; young & marty, 1986; hayek et al., 1991; solounias & moelleken, 1992; franz-odendaal & solounias, 2004; semprebon et al., 2004; merceron & ungar, 2005; merceron et al., 2005, 2006, 2007; palombo et al., 2005; charles et al., 2007; schubert et al., 2006; scott et al., 2006; demiguel et al., 2008; ungar et al., 2008, in press; valli & palombo, 2008, merceron et al., 2010; schulz et al., 2010, and references therein). although the use of microwear analysis undoubtedly is an useful tool in palaeoecological studies, thus far, few or no studies have been performed trying to test differences (if any) in microwear patterns shown by wear facets formed during the different masticator phases (but see for example gordon, 1982; schulz et al., 2010). butler (1972) first described the mastication process of herbivore mammals, and mapped the position of wear facets and the direction of the striae formed during the two phases of the power stroke of the masticatory cycle: phase i, when vertical movements prevail up to centric occlusion and phase ii, when the initial vertical movements become horizontal and finally downward out of the occlusal contact. following butler’s (1972) idea, other authors (see e.g. hiiemae, 1978; janis, 1979, 1990; rensberger et al., 1984; joomun et al., 2008) investigated the progression of the check tooth pattern. they recognized that in phase i, shearing is predominant, while in phase ii, grinding prevails. however, in hypsodont grazing ungulates, shearing becomes predominant and phase ii tends to be lost (janis, 1979). pleistocene equus representatives have generally been regarded as typical grazers, because the microwear pattern of the lingual side of the paracone of the second upper molar (m2), the canonical point to perform analysis (see below), consists of fine, nearly parallel scratches, few pits, and no or very few gouges, and the number of scratches definitively outnumbers to the number of pits. this has been regarded as an important factor in distinguishing grazers from browsers (e.g. solounias & semprebon, 2002). therefore, equus cheek teeth seem to be particularly appropriate to test the consistency of microwear patterns across the whole occlusal enamel surface, because most of its surface is affected by shearing only (e.g. janis, 1979), avoiding disturbances related to the presence of enamel scars produced by differently oriented masticator forces. examination of microwear in equids, as well as in ruminants, has generally been carried out on the enamel surface of the paracone of m2 by means of a either a scanner microscope or stereomicroscope (solounias & moelleken, 1993; mainland, 1998; solounias & semprebon, 2002; rivals et al., 2008, mihlbachler et al., 2011 valli a.m.f. et al. 26 and references in those papers). however, in equids, the attrition/abrasion forces differentially affect the enamel surface of the cheek teeth because chewing pressures may vary along the tooth row. the anterior and posterior edges of the tooth row participate less in food processing, therefore very anterior and posterior teeth are affected by a more pronounced attrition (tooth to tooth contact), with higher pressures on molars than on premolars. taking into account the peculiar development of anterior/posterior tilts characterising cheek teeth in horses, analysing the occlusal surface of p4 and m1 could be particularly appropriate in inferring dietary behaviour because, in these teeth, the main stress is almost perpendicular to the tooth mesio-distal axis, thus the enamel prisms are not much affected by this tooth tilt. this is the reason why we have decided to analyze the microwear patterns on several points of the enamel of an upper premolar in the twofold aim of investigating on the suitability of the p3-4 in inferring dietary behaviour of fossil horse, and testing the consistency of the microwear patterns on the whole enamel occlusal surface of a grazer. we have chosen to carry out the test on an extraordinarily well preserved upper premolar (either p3 or 4) of a stenonoid horse, equus altidens granatensis, from barranco leon 5 (late early pleistocene, guadix-baza basin, spain, alberdi, 2010) (fig. 1). this species has been regarded as a grazer (alberdi, 2010; alberdi & palombo, 2012 and references therein) therefore the arrangement of enamel scars on the whole enamel of the tooth occlusal surface should be roughly constant. although we are aware that, due the intrinsic characteristic of the microwear methods, reliable results can be obtained only by analysing a statistically consistent sample, we consider to preliminarily test the soundness of the method as a first fundamental step before developing and improving the study by means of an adequate number of specimens. 2. materials and methods analysis was performed on a left upper premolar (either p3 or p4 = p3-4; catalogue number: bl02 31 1692) from the latest early pleistocene fossiliferous deposit of barranco leon 5 (gaudix-basin, spain, blain et al., 2011; duval et al., 2009; toro-moyano et al., 2009). the specimen, stored at the museum of orce (granada, spain), has been chosen because of its good preservation status, allowing the whole surface of the enamel to be analysed. observations were done directly on the tooth at 500x magnification, using the quanta200 fei sem at 25 kv (museo nacional de ciencias naturales, madrid). quantitative analysis was performed using the microwear 4.02 software program (ungar, 2001) on a surface of 500x450 µm². scars are categorised as pits if their width to length ratio is > 1/4 and scratches if their width to length ratio is < 1/4 (solounias et al., 1988; teaford, 1988; solounias & hayek, 1993). pits are considered to be “large” or “small” according to their maximum diameter (whether it exceeds 15 μm or not; merceron et al., 2004). scratches are described as “coarse” (=“wide”) or “fine” according to their width (whether it exceeds 15 μm or not; merceron et al., 2004). they are also categorised as “long” or “short” depending on their length (whether it is equal to or longer than 250 μm, or less than this value; the scars which could extend out of the field of the picture have not been considered; valli & palombo, 2008). the number of “gouges” (scars deeper and several times larger than large pits with irregular outlines; solounias & semprebon, 2002), and “cross scratches” (defined as the number of crosses among the scratches, independent of their orientation) were counted. fig. 1 position of the fossil deposit of barranco leon 5 (bl5; guadix-baza basin, spain; modified from alberdi, 2010). the white area represents the guadix-baza basin. fig. 2 left upper p3-4 (bl02 31 1692) of equus altidens granatensis from barranco leon 5, spain. the numbers indicate the points (loci) where the microwear analyses have been carried out. how homogeneous are microwear patterns on a fossil horse tooth? preliminary … 27 pits scratches gouges large small tot length sd width sd % short fine long fine long coarse tot length sd width sd % cross point 1 2 7 9 4.14 2.48 1.87 0.93 13.85 49 6 1 56 31.35 27.71 1.07 0.60 86.15 38 1 point 2 0 41 41 2.78 1.27 1.33 0.35 26.11 116 3 0 116 16.70 19.32 0.82 0.33 73.89 51 0 point 3 0 53 53 2.06 0.80 1.03 0.31 35.33 97 0 0 97 16.65 13.27 0.89 0.41 64.67 46 0 point 4 0 34 34 2.37 1.73 1.12 0.60 15.38 181 6 0 187 16.99 18.99 0.81 0.41 84.62 85 0 point 5 0 31 31 1.98 1.37 1.06 0.43 24.80 91 3 0 94 19.27 17.67 0.94 0.45 75.20 38 0 point 6 0 13 13 1.93 0.78 0.99 0.41 13.00 81 5 1 87 22.18 24.47 0.89 0.56 87.00 28 0 point 7 0 22 22 2.82 1.43 1.34 53,0 17.32 97 8 0 105 22.13 23.26 0.99 0.46 82.68 44 0 point 8 1 5 6 5.00 2.49 2.41 2.19 7.89 64 6 0 70 28.51 27.40 1.03 0.51 92.11 32 0 point 9 3 12 15 3.83 4.34 1.74 1.60 15.00 80 4 1 85 22.35 18.71 0.90 0.71 85.00 26 0 point 10 1 23 24 2.06 0.96 1.05 0.43 27.27 57 4 0 64 26.25 22.69 0.85 0.43 72.73 17 0 point 11 1 43 44 2.54 2.33 1.29 0.76 30.77 95 3 1 99 16.70 18.58 0.86 0.60 69.23 19 0 point 12 1 11 12 1.96 0.94 1.32 1.04 21.43 37 7 0 44 34.28 31.51 0.82 0.33 78.57 29 0 point 13 4 13 17 4.45 2.65 2.79 2.21 27.42 42 1 2 45 24.42 24.70 1.15 1.34 72.58 8 2 point 14 0 10 10 2.47 1.65 1.11 0.45 17.54 47 0 0 47 17.15 11.14 0.92 0.40 82.46 11 0 point 15 2 15 17 3.24 2.42 1.67 1.29 20.99 60 4 0 64 22.81 25.56 0.86 0.33 79.01 24 0 point 16 2 17 19 2.91 3.79 1.53 1.59 22.09 65 2 0 67 15.95 22.32 0.74 0.38 77.91 14 0 point 17 1 23 24 2.99 1.92 1.50 1.12 21.82 81 5 0 86 20.31 20.92 0.99 0.52 78.18 33 1 point 18 0 11 11 2.04 0.74 1.10 0.36 16.18 55 2 0 57 18.98 18.44 0.94 0.52 83.82 15 1 point 19 2 27 29 3.81 3.12 1.70 1.14 33.33 50 7 1 58 27.41 29.17 1.14 1.14 66.67 20 0 point 20 1 22 23 2.46 1.35 1.39 0.59 26.74 56 6 1 63 29.00 28.26 1.00 0.77 73.26 58 0 point 21 0 16 16 2.32 1.54 1.50 1.43 21.33 53 6 0 59 28.10 29.57 0.71 0.45 78.67 35 0 point 22 0 14 14 2.15 1.22 1.31 1.05 17.07 61 6 1 68 29.42 25.33 0.88 0.78 82.93 46 0 point 23 0 25 25 1.77 0.72 0.95 0.37 25.25 69 5 0 74 24.58 24.95 0.74 0.48 74.75 35 0 point 24 1 18 19 3.25 3.46 1.32 1.09 22.89 62 1 1 64 19.38 15.16 0.86 0.66 77.11 18 1 point 25 1 11 12 2.60 3.63 1.48 1.89 16.00 60 3 0 63 24.67 17.23 0.86 0.53 84.00 25 0 point 26 0 35 35 2.03 1.17 1.14 0.55 25.55 97 5 0 102 21.20 21.23 0.74 0.42 74.45 35 0 point 27 0 20 20 2.23 24.31 1.07 0.37 32.26 40 2 0 42 26.93 24.31 0.89 0.59 67.74 19 0 m1-2 36-1520 3 34 37 2.60 1.75 1.41 0.69 39.36 55 1 1 57 13.45 7.98 1.09 0.67 60.64 13 2 m1-2 i54 13 4 51 56 2.47 1.25 1.51 0.99 36.36 95 3 0 98 11.81 12.47 0.74 0.29 63.64 19 0 tab. 1 results of the microwear analysis of three teeth of equus altidens granatensis from barranco leon 5. analyses carried out on 27 enamel points of the left upper p3-4 (bl02 31 1692) and on the lingual side of the paracone of m1-2 (specimens bl02 36-1520, right, and bl03 i54 13, left). photomicrographs of the dental occlusal surface were taken at the following points (loci; fig. 2): 1-2 on the parastyle, 3 to 6 on the labial side of the paracone, 7-8 on the metastyle, 9-10 on the labial side of the metacone, 11-13 on the postfossette, 14 to16 on the prefossette, 17-18 on the lingual side of paraloph, 19-20 on the lingual side of protocone, 21 to 23 on the pli caballin, 24 to 27 on the lingual side of the hypocone. the results of the analyses are shown in table 1. results obtained have been compared with those resulting from the analysis of microwear patterns, of two other specimens of e. altidens granatensis from the same locality, a right (bl02 36-1520) and a left (bl03 i54 13) upper molars (both either m1 or m2 = m1-2). in the present study (because of the preservation of the molar surface), only the locus n° 15 has been analysed. the results are shown in table 1. in order to evaluate the consistency of microwear patterns at different points of the enamel on the occlusal surface, as well as to test the significance of differences in pattern found among the examined micro-areas, six independent variables (number of small and large pits; number of short, long coarse and long fine scratches; and number of gouges) were analysed by means of a multivariate analysis test (sokal & rohlf, 2001). the analysis was performed using the correspondence analysis (ca) test of the past software program (hammer et al., 2001), which is especially appropriate for count data, such as ours. 3. microwear patterns on the lingual side of the paracone (locus 15), the microwear pattern shows parallel fine scratches, located mainly at the centre of the analysed micro-area (fig. 3). the inclination with respect to the lingual-labial axis ranges from about 0° to 15°. small pits and more inclined scratches can be detected on the lateral side of the photomicrograph, but scratches are more abundant than pits on the whole of the examined surface (tab. 1). short or very short scratches (scratches with width to length ratio near to 1/4), sometimes not much different from pits, prevail. a few long scratches (≥ 250 μm) are present. some look like they consist of several shorter marks arranged along the same line. cross scratches are fairly abundant, comprising more than one third of the total number of scratches (24 against 64; tab. 1). the microwear patterns of other analysed microareas are roughly comparable, but some differences are detectable especially with regards to the scratch (always the most numerous) to pit ratio, which varies from 92.11%,on the posterior side of the mesostyle (locus 8), to 64.67% on the labial side of the paracone (locus 3) (tab. 1). short (sometimes very short) scratches and small pits predominate. long scratches are not very abundant. long coarse scratches are scanty, clearly detectable only on about one third of the examined micro-areas particularly on the postfossette and on some loci of the labial and lingual sides of the tooth (tab. 1). gouges, definitely larger than large pits, are rare, with valli a.m.f. et al. 28 only six being found on five points, whilst cross scratches can be locally abundant: their frequency ranges from 52% to 85% (tab. 1). 4. statistical analysis results of statistical analysis are shown in fig. 4 and fig. 5, where the data are plotted into the new coordinates. the eigenvalues and the variance explained for each eigenvector are given in table 2.a. the first three eigenvectors explain 89.06% of the variance. considering new axes 1 and 2 (fig. 4), the position of the loci along axis 1 is directly proportionate to the number of small pits and inversely proportionate to the number of gouges, coarse scratches, large pits, fine and short scratches. the position of the loci on axis 2 is directly proportionate to the number of gouges, coarse scratches, large and small pits and inversely proportionate to the number of short and fine scratches. the more gouges, coarse scratches and large pits are counted in one locus the more it is inclined towards the negative values on axis 1 and the positive values on axis 2 (as for the loci 13, 1 and, in lesser proportion, 24). the more fine scratches and fewer small pits are counted (in the absence of gouges and coarse scratches) the more the locus plots along the negative value of the axis 2 (like locus 8). the central area of the 95% confidence ellipse contains two loci on the prefossette (15 and 16), two on the lingual side of paraloph (17 and 18) and one on the lingual side of protocone (20). very near are positioned loci on the pli caballin (21, 22 and 23), on the lingual side of the hypocone (25), on the prefossette (14, just under locus 15), on the labial side of the metacone (10), and on the lingual side of the hypocone (26). the most peripheral loci from the centre (but still inside the ellipse) are the locus n° 1 (on the parastyle), the n° 3 (on the labial side of the paracone), the n° 8 (on the metastyle), the n° 9 (on the labial side of the metacone), the n° 11 (on the postfossette) and the n°27 (on the lingual side of the hypocone). these loci, except n° 1 and n° 3, fall in the posterior half of the tooth. the locus n° 13, on the postfossette, is the only one falling outside the 95% confidence ellipse. the position of the loci along axis 3 (fig. 5) is directly proportionate to the number of fine scratches, large pits, coarse scratches and small pits and is inversely proportionate to the number of short scratches. the higher the ratio of “fine scratches/short scratches” the more the locus will fall far within the positive values, like loci 12 (which scores “0.19”), 19 (“0.14”), 20(“0.11”), and 21 (“0.11”). the central area of the 95% confidence ellipse contains loci on the labial side of the paracone (5), on the prefossette (15 and 16), on the lingual side of paraloph (17), on the pli caballin (23), on the lingual side of the hypocone (26), and on the parastyle (2). very near are positioned loci on the parastyle (1), on the metastyle (7), on the labial side of the metacone (9 and 10), on the pli caballin (22) and on the lingual side of the hypocone (25). the most peripheral loci are n°12 (on the labial side of the metacone), n°19 (on the lingual side of protocone), and n° 8 (on the metastyle). again, the locus n° 13 is the only one falling outside the 95% confidence ellipse. as in fig. 4, loci 15, 16 and 17 fall within the central area of the ellipse. the loci on the pli caballin (21-23) even if they do not fall within the centre, lie in proximity to the locus n°15, the classical point choose in the microwear analysis, in both fig. 4 and fig. 5. again, some of the most peripheral points are situated on the posterior half of the tooth (8, 11, 13, 24, but not 9, 10). fig. 3 photomicrograph (x500) the point n° 15 (see fig. 2) of the enamel surface of equus altidens granatensis left upper p3-4 (bl02 31 1692). fig. 4 correspondence analysis among 27 points (loci) on a upper p3-4 of equus altidens granatensis. first and second eigenvectors. the 95% confidence ellipse is indicated. how homogeneous are microwear patterns on a fossil horse tooth? preliminary … 29 adding to the multivariate analysis data from specimens bl02 36-1520 and bl03 i54 13, the eigenvectors change slightly (tab. 2.b) but without any substantial change in the general pattern of the setting of analysed loci (fig. 6). in the axis 2 versus axis 3 graphic, the m12 loci fall well inside the 95% confidence ellipse, while in the axis 1 versus axis 2 upper m1-2 (36-1520), it is closer to the border of the 95% confidence ellipse (because of the two gouges found on it). 5. discussions whether the differences in microwear patterns of nearly contiguous enamel areas are related to the intrinsic properties of the food, to the presence of exogenous grit (see inter alios rivals & semprebon, 2006; semprebon & rivals, 2007, 2010), or to stochastic factors connected to the local resistance to tensile and pressure stress during masticatory processes, is a still unsolved question. as equus from barranco leon is concerned, results obtained indicate that the main differences in macrowear patterns (in terms of dental scars among the various areas of enamel on the same tooth) are limited to a few zones of the enamel surface. nonetheless, considering the quite homogeneous masticatory stress across the tooth, its flat occlusal surface, and the processing of a roughly similar food, it is not easy to understand what is producing the inconsistencies among microwear patterns shown by loci close to each other. differences depend mainly on the pits/scratches ratio, but also on presence/absence of coarse scratches, large pits and gouges. the latter two scars are believed to be related to feeding habits that include seeds, hard fruits or even roots (solounias & semprebon, 2002; semprebon et al., 2011) but in the present study, a few gouges and/or large pits might be caused by exogenous grit, swallowed together with food, which locally damaged the enamel surface. indeed, scars herein regarded as “large pits” mainly show a more irregular outline than the outline of the large pits detectable on the teeth of animals whose diet includes seed and hard fruits. on the other hand, the microwear patterns shown by the lingual enamel of the paracone (locus n°15), the point classically chosen for analysing microwear in ruminants, falls very near the central area of the 95% confidence ellipse. as a result, the lingual enamel band of the paracone, can be considered the best point for analysing microwear in equus representatives in m2 as well as in p3-4, according to the results obtained. in addition, on the latter also the pli caballin could be confidently analysed to infer the dietary behaviour of horses. according to our result, if in a sample of horse teeth to be analysed, the number of available m2 is scanty, it is possible to increase the sample size, adding upper p3-4 (see fig. 6). fig. 5 correspondence analysis among 27 points (loci) on a upper p3-4 of equus altidens granatensis. second and third eigenvectors. the 95% confidence ellipse is indicated. fig. 6 correspondence analysis among 27 points (loci) on a upper p3-4 and 2 upper m1-2 of equus altidens granatensis. a) axis 1 versus axis 2. b) axis 2 versus axis 3. the 95% confidence ellipses are indicated. valli a.m.f. et al. 30 fig. 7 bivariate plot of the average number of scratches versus average number of pits for extant browsers, mixed feeders, grazers (data from solounias et al., 2000; aa alces alces, lw litocranius walleri, cd cephalophus dorsalis, be boocercus euryceros, ti tragelaphus imberbis, cn cephalophus niger, ts tragelaphus strepsiceros, oj okapia johnstoni, cs cephalophus sylvicultor, gc giraffa camelopardis, cp capricornis sumatraensis, to taurotragus oryx, gg gazella granti, tr tragelaphus scriptus, gt gazella thomsoni, mm muntiacus muntjak, bt boselaphus tragocamelus, ci capra ibex, ce cervus canadensis, cu cervus unicolor, oc ovis canadensis, ke kobus ellipsiprimnus, ct connochaetes taurinus, tq tetraceros quadricornis, bb bison bison, hn hippotragus niger, ax axis axis, cv cervus duvauceli, oo ourebia ourebi, sc syncerus caffer), left upper p3-4 (bl02 31 1692; 27 loci), right m1-2 (bl02 361520) and left m1-2 (bl03 i54 13) of equus altidens granatensis from barranco leon. numbers = p3-4 loci. tab. 2 eigenvectors of the correspondence analysis test (ca), with respective eigenvalues and % variance, for a) 27 loci on a upper p3-4 of equus altidens granatensis, b) 27 loci on a upper p3-4, and 2 upper m1-2 of equus altidens granatensis. our results are also consistent with those obtained by kaiser t.m. (2002), according to which in hypsodont perissodactyls, like equus, the chewing direction, along the horizontal plane, tends to become exclusively transverse. indeed, the loci which appear as anomalous with respect to the average pattern shown by the microwear of the e. altidens granatensis from baranco leon, are mostly located on the posterior part of the tooth (e.g. loci 11 and 13). despite the reliability of most of the analysed loci with the masticatory stress and movements, some inconsistencies still remain unexplained. for instance, what about loci 24-26, which may possibly fall within the phase ii area, albeit they show a pattern different from that of other loci of the same area? why does locus 3 present a microwear pattern so different from locus 2, which is located on the same enamel band? could these differences have explained by a different orientation relative to the chewing direction? finally, how many stochastic factors, such as the ingestion of sediments particles, may affect microwear patterns? results obtained, albeit preliminary, on the one hand stress once more the individual variation in food assumption and consumption, as well as the need of large samples and the support of complementary analyses – such as mesowear (kaiser et al., 2000; kaiser & forteluis, 2003) and stable isotopes (e.g., cerling et al., 1997; mihlbachler et al., 2011) – to validate inferences drawn by microwear analysis. on the other hand, they indicate the potential efficacy of the additional test herein proposed to better understand the reliability and limits of microwear analysis. 6. palaeodietary interferences as far as the diet of the horse from barranco leon 5 is concerned, plotting the number of scratches of this horse and extant ruminants (data from solounias et al., 2000) versus the number of pits, our data forms a main cloud lying between the grazing and the mixed feeding taxa (fig. 7). a few loci are nested inside the grazers, a few inside the mixed feeders and some are scattered over both groups. only locus 4 (on the labial edge of the paracone) falls far from the others, because of its large number of scratches (tab.1). loci on the prefossette (15 and 16), and on the pli caballin (22 and 23) fall between grazers and mixed feeders, with locus 22 nearest to the second group. all in all, the pattern of dental microwear shown by e. altidens granatensis from barranco leon 5, for upper p3-4, is closer to those shown by seasonal mixed feeders than by strict grazers. adding the two m1-2, one (bl02 36-1520) falls near a grazer taxon, the other (bl03 i54 13) in the range of the mixed feeders. these data, in the first approximation, can be considered consistent with those analysed on the p3-4. in any case, more data are necessary in order to support the hypothesis of any relationship between the increase in moisture between 1.3 and 1.0 my (blain et al., 2011) pointed out for the localities of barranco leon and the dietary behaviour inferred by microwear analysis. 7. conclusions our study is a preliminary work aimed at understanding the consistencies in microwear patterns on the occlusal surface of dental enamel and the use of single locus for palaeodiatary analyses. our data suggest that the differences, at least for horses, are limited to a few zones. in particular, the lingual side of the paracone, the classic locus chosen for microwear analysis in ruminants and equids, falling at the centre of the distribution obtained, considering all the loci on fig. 2. on our sample, the loci on the pli caballin could also be confidently analysed to infer dietary behaviour. they are all judged consistent with the data obtained on m1-2 from the same locality. results obtained also suggest that the use of p3-4 can be useful in inferring palaeodietary behaviour when the number of available m2 is scanty. how homogeneous are microwear patterns on a fossil horse tooth? preliminary … 31 thus, our analysis shows that microwear methodology could be extended to other loci and teeth in addition to the classic one considered. of course, more data and more studies would be necessary in order to further improve the methodology and fully understand its limits. acknowledgements we have to thank to tormo l. 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(2008) feeding behaviour of middle-size deer from the upper pliocene site of saint-vallier (france) inferred by morphological and micro/mesowear analysis. palaeogeography, palaeoclimatology, palaeoecology, 257, 106-122. young w.g., marty t.m. (1986) wear and microwear on the teeth of a moose (alces alces) population in manitoba, canada. canadian journal of zoology, 64, 2467-2479. ms. received: january 31, 2012 final text received: february 21, 2012 imp.monicabini an itinerary around the apuan alps (tuscany, italy): an example of landscape modelled by different agents monica bini phd student, università di bologna. research carried out at dipartimento di scienze della terra, università di pisa, email: bini@dst.unipi.it abstract: m. bini, an itinerary around the apuan alps (tuscany, italy): an example of landscape modelled by different agents. (it issn 0394-3356, 2005). the combined action of various exogenous agents, together with the powerful endogenous thrust and anthropic activities, have all contributed to the genesis of the current apuan landscape. this landscape is characterised by numerous geosites, among which the most important is certainly the antro del corchia. this karst cavity of international scientific interest, since its opening to the general public has become an important attraction of the park of the apuan alps. however, it tends to be visited purely as an isolated monument, without links with the rest of the area, which offers, also in the immediate surroundings, the chance to observe various other sites of geological or geomorphological interest of comparable scientific value. the exceptional drawing power of the cave could therefore be used to better divulge information relative to those other lesser known nearby sites, which, connected together in an easily followed itinerary, could tell the story of the area from its geological and geomorphological characteristics to the significant impact of man on this landscape. riassunto: m. bini, un itinerario attraverso le alpi apuane (toscana, italia): un esempio di paesaggio modellato da differenti agenti. (it issn 0394-3356, 2005). la concomitante azione di diversi agenti esogeni, unita alla poderosa spinta endogena e all’attività antropica, ha portato alla genesi dell’attuale paesaggio apuano che è caratterizzato dalla presenza di numerosi geositi tra i quali spicca sicuramente l’antro del corchia. la cavità carsica di interesse scientifico internazionale, dal giorno della sua apertura al pubblico è divenuta una importante attrazione del parco delle apuane, ma sfortunatamente è visitata come un monumento isolato, senza legami con il resto del territorio, che offre, anche nelle immediate vicinanze, l’opportunità di osservare altri siti di interesse geologico geomorfologico, di altrettanto valore scientifico. l’eccezionale potere attrattivo dell’antro potrebbe essere sfruttato per diffondere le conoscenze relative a questi siti meno noti, che, collegati tra loro in un facile itinerario, potrebbero raccontare pienamente la storia del territorio dalle peculiarità geologiche a quelle geomorfologiche fino alla incisiva impronta antropica. keywords: geomorphosites, apuan alps, mt. corchia. parole chiave: geomorfositi, alpi apuane, m. corchia. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 197-201 1. introduction the apuan alps are rich in geosites and particularly geomorphosites, yet today probably the only site that has been adequately exploited, and the only one recognised by the local community and tourists is the antro del corchia. since its opening to the general public in august 2001 it has received a great number of visitors, who however very often see the cave as an isolated monument, without being able to appreciate the natural context within which it is located. the exceptional drawing power of the antro del corchia could be better exploited also to divulge important scientific concepts associated with the presence of other geological-geomorphological sites which taken singly would otherwise be less well known to the public. these sites, linked to the cavern in a single tourist itinerary, could help fully understand the natural and cultural features of the apuan area. these range from its geological peculiarities and modelling by exogenous agents, to the many signs of human influence which have had a significant impact on an area long characterised by mining activities. this paper proposes a touristic-cultural itinerary which makes the most of the apuan area by means of a series of geosites in the surrounding area of the antro del corchia, so as to exploit the already existing tourist flow to the area. the sites included in the itinerary are the following: • levigliani mercury mine • hercynian discontinuity of mt. corchia • antro del corchia • marble quarries of mt. altissimo • padule di fociomboli for some of these sites emphasis has been placed on obviously non-geological features, such as the biological and historical-cultural component, which were considered particularly important and able to increase the value of the single elements. the itinerary, conceived as an informative and discovery route of the area, proposes some points of reflection on the close link between geotopes and biotopes and on the difficult, but not impossible, relation between safeguarding cultural assets and exploitation of natural resources. 2. itinerary the itinerary starts with a visit to the historical mercury mine of levigliani (fig.1). it is located just before entering the village of levigliani, following the 198 m. bini provincial road, near the first turning for levigliani on the road that runs along the side of canale del bosco. along this channel there are the remains of the mining works for the extraction of mercury and cinnabar, whilst on the orographic left there are the entrances to the mining galleries (fig. 2). active from medieval times, when it gave an impulse to the development of the village of levigliani, the mine is today delapidated and risks deterioration and general decay. the interesting mineralisation, which offers a paragenesis unique in italy, follows the quartz veins that reappear in the paleozoic porphyroid schists. of particular importance is the presence of native mercury in metallic drops and cinnabar, which was used in the past for the manufacture of red pigments for the characters of illuminated manuscripts and ecclesiastical books (mancini, 1998). there are numerous rare minerals, some of which, such as leviglianite, were discovered here for the first time. closed down in 1970, after various vicissitudes, the mine is no longer economically viable for extraction, but if opportunely re-equipped and restored it could certainly become an economic resource from the tourist point of view. leaving behind the mine we proceed along the fig. 1 the itinerary. l’itinerario. provincial road to the village of levigliani, from where, with the shuttle bus of the parco delle apuane, we go towards the antro del corchia. during the uphill trip it is possible to see the torrioni del corchia (fig. 3), at the base of which there is the passage between the paleozoic formations of the hercynian basement and the autochthonous calcareous beds (carmignani & giglia, 1983; tucci, 1980). the presence of this landscape, which corresponds to the discontinuity with hercynian discordancy, makes the landscape particularly spectacular, given the different responses of the two rock types to erosion and weathering. above all it is a key point of the area for the understanding of the geological dynamics of the apennines. in fact, it is here where the structurally deepest zone of the northern apennines crops out. from the bus stop, through an artificial entrance created inside an abandoned mining extraction we enter the antro del corchia. with its 50 km and more of galleries and a depth of 1210 m, the cavern is the most extensive italian karst cavity and one of the largest in the world. via a walking itinerary of about two hours we can savour the typical fascination of the hypogeous karst processes, and we can understand important elements of the geological evolution of the apuan mountain chain, such as the various phases of 199an itinerary around the apuan ... stasis and tectonic uplift. in fact, the cave has a complex network of galleries, made up of large horizontal galleries connected by vertical shafts cut along the main joint patterns. the arrangement of the galleries, in three well defined levels, at 1400 m, 1200 m and 850 m a.s.l. reflects three successive moments of tectonic stasis of the apuan chain occurring respectively in the middle-lower pliocene, the lower pliocene, and in the middle-upper pleistocene. the periods of uplift of the apuan alps originated the vertical shafts (piccini, 1991). another undoubtedly typical feature of this area, without which it would be difficult to understand the culture and nature of this landscape, is that of the marble quarries. visible from the versilia coastline, the quarries are chiselled into the landscape and seem to be in an eternal struggle with the carbonatic rock, with its natural cavities. in this particular equilibrium, the exploration of the karst cavities has often identified good sections and vice versa the quarrying activity, above all in the galleries, has sometimes revealed previously unknown branches of the karst cavities. this situation lends a certain importance to the controversial story of the discovery of the antro del corchia, explored for the first time by emilio simi, naturalist and local entrepreneur. for a long time it was thought that simi had discovered a branch of the cavern during marble excavation in his quarries. in reality, as the note of professor l. pilla shows here, it was initial exploration of the karst cavity that prompted simi in 1841 to start quarrying activities. “on the cliffs of mt. corchia that overlook levigliani there was the discovery of a cavern entrance in 1840, which, arousing the curiosity of many, prompted signor simi to undergo operations in order to penetrate the cavity […]. one of the most notable things that was observed was that once the stalactitic crusts covering the walls were removed, these same walls were seen to be of snow-white statuary marble.” the double interest that mt. corchia stimulates, and which makes it an ongoing bone of contention between naturalists and quarrymen, was almost prophetically noted by simi himself who, in 1872, wrote: “if in that beautiful group of mountains which […] crown the rich versilia, one feature deserves more than any other to attract the attention of the naturalist and the greed of the speculator, then that feature is without doubt mt. corchia” (bartelletti & amorfini, 2001). this dual interest is today still very much reflected in the landscape. in fact, near the entrance to the karst cavity, some highly impressive grottoes open in the galleries, veritable cathedrals of marble cut into the mountainside. probably the best known is borra larga, whose entrance is slightly higher up from the main cavern. another example of a different type of mining technique, the open quarry, can be seen along the path towards the padule di fociomboli, where we can observe on monte altissimo a sharply cut summit-level fig. 2 – system of mercury mine of levigliani (photo by s. mancini 1988). impianti della miniera di mercurio di levigliani (foto di s. mancini 1988). fig. 3 the hercynian unconformity of monte corchia. la discontinuità ercinica di monte corchia. 200 quarry. it is one of those which most evidently modify the landscape of the area, it having been opened on the main ridge of the mountain (fig. 4). due to this man-made activity the crest has been lowered and has taken on the typically geometric shape and snow-white colour now very much the emblem of these mountains. more precisely, this white tone is not due only to the marble quarry walls, but also to another feature typical of this area, the ravaneti, piles of variously shaped blocks and stone debris originating from the worked waste material and which cover wide areas of the flanks of the apuan alps. the ravaneti can be seen at various points of the itinerary, but because of its extension and particular location, the mt. altissimo example is the most impressive. on this ravaneto, as on many others, it is possible to see the steep and winding access roads for the trucks that carry the marble down. in effect, in an impervious area like that of the apuan alps the problem of marble transport has always been of primary importance. for years the way of getting the marble blocks down was by means of the vie di lizza. these were hazardous tracks, furrowed into the steep apuan slopes, along which the marble blocks were hoisted down attached to a large wooden sledge made to slide down on massive trunks, known as "parati", and kept in position with ropes held by a small team of men. only at the end of the 1960s did truck transport on the access roads replace the dangerous technique of "lizzatura". since then the list paths of the area, an important historical feature, risk disappearing altogether. there is not even an adequate count of how many there are, unlike that carried out in the nearby massa district (bradly & medda, 1989). a few remains of these ancient tracks can be seen from the road leading from the antro del corchia to the village of levigliani. returning to levigliani following the road to pian di lago and passo croce we reach fociomboli and from here, following c.a.i. footpath n°11 we arrive at the padule di fociomboli (peat bog of fociomboli) recognised as a “site of eu interest” due to its notable naturalistic features (fig. 5). the current peat bog is the remains of an ancient glacial lake. a careful look at the landscape enables us to reconstruct the appearance of the area during the last glaciation. one of the southernmost glaciers of the apuan chain occupied this area. it extended along the northern walls of the mountain starting from a height of 1500-1600 m, as shown by the current glacial cirques, and reached, uncovering some rocky spikes, as far down as 700 m along the val terreno. this is m. bini fig. 4 the “cervaiole” quarry in the m. altissimo area. la cava “le cervaiole” su monte altissimo. fig. 5 view of the peatbog of fociomboli. vista panoramica del padule di fociomboli. 201 shown by the presence of a frontal moraine, and at 750 ÷ 800 m in the valley of canale delle fredde, of large boulders with glacial striations (braschi et al., 1986; federici, 1981). in the area of torretta at 1150 m. there is a stationary moraine, that is left by the glacier in a phase of retreat. it is this moraine that has caused the formation of the lake which today has become one of the few peat bogs of the apuan area. located on impermeable rocks, the peatbog of fociomboli is constantly crossed by streams that maintain a regular humidity. in addition, because they originate in the overlying calcareous relief, these waters neutralise the acidity of the soil. the combined effect of these characteristics makes this area a precious habitat for unusual and often rare flora and fauna, clearly indicating the close relationship between geotopes and biotopes (bartelletti & amorfini, 2001) 3. conclusions the itinerary proposed ambitiously intends to show both tourists and members of the local community, how geological, goemorphological and man-made elements of the same area are not detached from each other, and how, even if in constant competition with one another, they overlap and integrate in a common landscape-forming process. the presence within the fociomboli habitat of rare or unusual biological species enables us to observe the close relationship between geotope and biotope, showing how the lack of protection of the physical environment has a negative influence on the biological environment. furthermore, the presence of two mining sites (the altissimo open quarry and levigliani mine) prompt us to reflect on the difficult but not impossible co-existence of this type of activity and the safeguarding of natural resources. in particular, we can see how the quarrying activity can on the one hand be a menace for the local natural resources (the altissimo and antro del corchia), but on the other, it can itself become a cultural resource (levigliani mine, list paths). the idea of this proposed itinerary is to get away from the visit to a single landscape element and move towards a more integrated visit of the nature and culture of an area. this should be a small step in the direction of a knowledge-based approach which contributes to a true safeguarding and exploitation of natural resources that goes beyond an exclusively restrictive conservation. aknowledgements this work was supported by funds of the research project “the environmental resources of the lucca area: an important patrimony to safeguard and exploit” of the fondazione cassa di risparmio of lucca, at the department of earth sciences of the university of pisa. references bartelletti a. & amorfini a. (2001) corchia nel cuore delle apuane suppl. n.148 de “la rivista del trekking”, agosto amichetti editore, parma bradley f. & medda e. (1989) le strade dimenticate vie di lizza e discesa del marmo nelle alte valli massesi amministrazione provinciale di massa e carrara. b raschi s., d el f reo p. & t revisan l. (1986) ricostruzione degli antichi ghiacciai sulle alpi apuane. atti soc. tosc. sci. nat., mem., serie a. 93 pp. 203-219. carmignani l. & giglia g. (1983) il problema della doppia vergenza sulle alpi apuane e la struttura del monte corchia. mem. soc. geol. it. 26, pp. 515525. federici p.r. (1981) the quaternary glaciation on the sea ward side of the apuan alps riv. geogr. it. v. 88, pp. 183 –199. mancini s. (1998) miniere in versilia. storia e itinerari petrarte edizio, pietrasanta. piccini l. (1991) ipotesi sulla origine e sulla evoluzione del complesso carsico del monte corchia corchia 916° congr. fed. spel. it., stazzema. tucci p. (1980) le metamorfiti della "serie scistosa basale" del monte corchia (alpi apuane)period. min. 49, pp. 57-148. an itinerary around the apuan ... imp.dewaeleetalgasmi geomorphosites of tozeur region (south-west tunisia) jo de waele1, felice di gregorio1, nabil gasmi2, maria teresa melis1 & mohamed talbi3 1department of geology, via trentino 51, 09127 cagliari e-mail: geoam@unica.it 2faculté de sciences humaines et sociales, 94, bd. du 9 avril 1938, 1007 tunis e-mail: nabil.gasmi@fshst.rnu.tn 3institut des régions arides, medenine, route de djorf km 22.5, 4119 medenine e-mail: talbim@ati.tn abstract: j. de waele et al., geomorphosites of tozeur region (south-west tunisia). (it issn 0394-3356, 2005). tozeur is the most important tourist town of south-western tunisia, situated in between the two salt lakes chott el djerid to the south and chott el gharsa to the north. this area is known for its luxuriant oasis in the middle of the desert (tozeur, gafsa, nefta etc.), the mountain chains to the north close to the border with algeria with its villages and waterfalls (tameghza, chebìka, midès), the mountain chain east of tozeur (jbel morra etc.) with its arid canyons, and the wide salt plains (chotts). tourists usually visit the region rapidly without staying overnight, overlooking and ignoring the great geomorphologic and geological interesting places and landscapes. therefore, in the framework of a research project performed by the department of geology of the university of cagliari in collaboration with the institut des régions arides at medenine and with the "faculté de sciences humaines et sociales" of tunis and financed by the sardinian regional government (r.l. 11 aprile 1996, n° 19), our multidisciplinary research team has studied twenty-one geosites and geological landscapes in the region of tozeur, with the purpose of constituting a network of geosites in these arid and semiarid areas. field work combined with remote sensing techniques have enabled to start preparing thematic maps of these geosites which, together with their description (genesis, evolution, state of conservation, proposals of valorisation, etc.) will be useful for obtaining financial aid for their protection and valorisation. the definition of morphostructural units landform analysis at a large/medium scale was performed by telegis laboratory, involved in these studies on southern tunisia from 1997 in collaboration with the institute des régions arides, applying remote sensing techniques on multi-spectral satellite images. during this project the interpretation keys for the image classification were created in the different steps of field observations and digital image processing. the radiometric and geometric responses were used for the discrimination of spectral units (lithological sequences) and textural units defined by photointerpretation techniques (structural and landscape units like anticlines, fault-controlled valleys or forms like chevron, etc.). many of the studied geomorphosites are represented by canyons (gorges de ben nebhana, sidi bou helal, thelja, en negueb, chaabet es sfa, ben hamed, midès, etc.) and waterfalls (grande cascade and cascade de l'oasis at tameghza, cascade de chebìka and its geological-structural features). others are related to aeolian and meteoric processes (barchan dunes of el ghadayer, morpho-sculpture of ong el jmel, yardangs of el ghadayer, nebkha fields of chamsa). the remaining geosites are an ancient lacustrine coastline testified by a lumachelle with cardium in the jehim oasis near tozeur, the anticline of brikis close to tameghza, and an ancient phosphate mine at chouabin (jbel chouabin close to redeyef), a representative part of chott el djerid, the delta of oued mellah and the alluvial cone of oued foum el khanga and the ancient oasis (corbeille) of nefta. these sites and landscapes of geological and geomorphological interest represent the entire geological history of the tozeur and the chotts region fairly well. this history starts from early cretaceous, and the various sites narrate the sedimentary and tectonic events, the palaeo-environmental and palaeo-climate episodes, the birth, development and extinction of animal and plant species, the geomorphological processes and depositional events, explaining the present morphology, climate and landscape in a most interesting scientific and educational way. the linking of all these places of geological and geomorphologic interest in networks of geosites along a thematic issue (the "living desert" network with nebkha and barchan dunes, yardangs and aeolian sculptures, the "rocks and water" network with waterfalls, mountains and canyons, the "earth’s memory" network across the canyons of jbel morra-sidi bou helal passing through more than 100 million years of earth's geological history, the “phosphate route” network with active and abandoned phosphate mines and their environmental impact and the “changing environment and climate” network with salt pans, fossil shorelines and abandoned oasis) give an interesting opportunity of telling the history of the earth, promoting geology and geomorphology to the local people and to the visitors. in fact, geological heritage can and should become a cultural and economical resource for the local people, and therefore these inhabitants should be taught understanding their natural and cultural environment, enabling them to use these elements in the framework of a touristic and sustainable development of their region. riassunto: j. de waele et al., geomorfositi della regione di tozeur (tunisia sud-occidentale). (it issn 0394-3356, 2005). tozeur è il principale centro turistico della tunisia sud-occidentale, situato tra i due laghi salati dello chott el djerid a sud e lo chott el gharsa verso nord. quest’area è rinomata per le sue belle oasi in mezzo al deserto (tozeur, gafsa, nefta ecc.), le catene montuose con i villaggi, le oasi di montagna e le cascate a nord vicino al confine con l’algeria (tameghza, chebìka, midès), la catena di montagne con i numerosi canyon ad est di tozeur (jbel morra, ecc.) e le grandi pianure salate (chotts). in genere i turisti visitano la regione molto rapidamente senza poter conoscere ed apprezzare i caratteri essenziali dei paesaggi e dei numerosi siti d’interesse geologico e geomorfologici presenti. per questo motivo il gruppo di ricerca multidisciplinare, composto da ricercatori del dipartimento di scienze della terra dell’università di cagliari, dell’institut des régions arides di medenine e della faculté de sciences humaines et sociales dell’università di tunisi, ha predisposto un progetto finanziato dalla regione autonoma della sardegna (l.r. 11 aprile 1996, n° 19), che ha consentito di individuare e classificare 20 geomorfositi e paesaggi geomorfologici nella regione di tozeur con lo scopo di creare un network di geomorfositi capaci di mettere in luce il valore del patrimonio geologico di quest’area desertica. il lavoro di rilevamento in campagna è stato combinato allo studio d’immagini satellitari per elaborare delle carte tematiche dei geomorfositi che, insieme alla loro descrizione (genesi, distribuzione, evoluzione, stato di conservazione, proposte di valorizzazione, ecc.) costituiscono un riferimento essenziale per la loro conservazione e valorizzazione. la definizione morfostrutturale delle diverse unità di paesaggio ad una scala medio-grande, mediante tecniche di remote sensing su immagini satellitari multispettrali, è stata eseguita nel laboratorio telegis dell’università di cagliari coinvolto negli studi in tunisia meridionale dal 1997 in collaborazione con l’institut des régions arides. le chiavi d’interpretazione per la classificazione delle immagini sono state create durante le campagne di rilevamento in loco e l’elaborazione delle immagini digitali in sede. le risposte radiometriche e geometriche sono state utilizzate per la discriminazione delle unità spettrali (sequenze litologiche) e delle unità tessiturali definite attraverso tecniche di foto-interpretazione (unità strutturali quali anticlinali, valli controllate da faglie o forme come chevron ecc.). molti dei geomorfositi individuati e studiati sono dei canyon (gorges de ben nebhana, sidi bou helal, thelja, en negueb, chaabet es il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 223-232 224 j. de waele et al. 1. introduction the concepts “geosite” and “geological heritage” became widely used since the beginning of the 90’s and researchers from all over europe started discussing on the conservation of geological sites and landscapes. the first important european meeting on geo-conservation was organised at digne-les-bains (france) in 1991 and during this event the “international declaration of the rights of earth’s memory” was ratified and a first attempt of cataloguing geosites was presented in order to start building a versatile data base (barca & di gregorio, 1991a; 1991b). since then our multidisciplinary research team has started inventorying geosites in sardinia covering almost the whole regional territory (barca et al., 1992; panizza v. & cannillo, 1994; barca et al., 1995; 1996; de waele et al., 1998; 1999; ardau & de waele, 1999; arisci et al., 2001; 2002; de waele et al., 2002; 2003a; 2003b; 2003c) and giving rise to a detailed work on geological heritage of the province of cagliari (barca & di gregorio, 1999). all these researches have been carried out in the framework of international research programs such as “geosites” of the international union of geological sciences started in 1996 and “geomorphological sites”, a working group found in 2001 by the international association of geomorphologists. the national studies have had a further impulse thanks to the italian cofin 2001-2003 project “geosites in the italian landscape: research, evaluation and valorisation”, in which framework two workshops have already been organised during which italian and foreign researches have confronted and discussed their scientific results. geoconservation is not yet properly developed in the african continent, although the first attempts are starting to obtain some preliminary results especially in south africa (reimold, 1999). our decennial experience on geosites and geomorphosites and starting from the concepts of geomorphological asset evaluation as defined by panizza m. & piacente (1993) and poli (2003), has brought our research team to start working also in north-african countries and thanks to several research projects financed by the sardinian regional government we have commenced cataloguing sites of geological and geomorphological interest in the middle atlas of morocco (de waele et al., 2003d) and in the tozeur region in tunisia (di gregorio et al., 2002). this paper describes the results of the researches on geomorphosites and geological heritage performed in the region of tozeur (south-west tunisia). 2. geology of the region tozeur is located in south-western tunisia, between the two salt lakes chott el djerid to the south and chott el gharsa to the north (fig.1). sfa, ben hamed, midès, ecc.) e cascate (grande cascade e cascade de l'oasis a tameghza, cascade de chebìka e le sue eccezionali caratteristiche geologico-strutturali). altri sono legati a processi eolici e meteorici (barcane di el ghadayer, morfoscultura di ong el jmel, yardang di el ghadayer, campi di nebkha di chamsa). i restanti geomorfositi sono: un’antica linea di costa lacustre testimoniata dal livello sedimentario a lumachelle con cardium nell’oasi di jehim presso tozeur, l’anticlinale di brikis a tameghza, un’antica miniera di fosfati a chouabin (jbel chouabin nei pressi del villaggio di redeyef), il delta dell’oued mellah, il cono fluvio-sedimentario dell’oued foum el khanga, un settore paesaggisticamente rappresentativo dell’immenso chott el djerid e l’oasi antica di nefta (corbeille). questi siti e paesaggi d’interesse geologico e geomorfologico rappresentano abbastanza compiutamente l’intera storia geologica della regione di tozeur e degli chott. questa storia geologica inizia nel cretaceo inferiore, ed i numerosi siti raccontano eventi sedimentari e tettonici, episodi paleo-ambientali e paleo-climatici, la comparsa, l’evoluzione e l’estinzione di specie animali e vegetali, i processi d’erosione e deposizione di sedimenti, che forniscono un quadro esauriente e completo della morfologia, del clima e del paesaggio attuale di elevato interesse didattico-culturale. l’interconnessione di tutti questi siti di interesse geologico e geomorfologico in network tematici (il network “deserto vivente” con le nebkha, le barcane, gli yardangs e le sculture eolico-meteoriche, il network “rocce ed acqua” con montagne, cascate e gole, il network “la memoria della terra” con gli attraversamenti dei canyons del jbel morra-sidi bou helal che consentono di percorrere nelle sequenze stratigrafiche più di 100 milioni di anni di storia della terra, il network “il sentiero dei fosfati” con miniere di fosfati attive ed abbandonate e il loro impatto sull’ambiente e il network “il clima e l’ambiente che cambia” con le antiche rive degli chotts, le pianure salate attuali ed oasi abbandonate) consente di raccontare la storia della terra, promuovendo la conoscenza dei fenomeni geologici e geomorfologici nei confronti sia della popolazione locale sia dei visitatori, in un ambiente semiarido ed arido dove sono limitate le possibilità di sviluppo. in tal senso, il patrimonio geologico può diventare una risorsa culturale ed economica di non trascurabile interesse per la regione. per questo occorre rendere gli abitanti consapevoli della ricchezza del loro ambiente naturale e culturale, creando le opportunità per utilizzare queste risorse nel quadro di uno sviluppo turistico sostenibile della loro regione. keywords: desert, geomorphosite, desertification, remote sensing, geotourism, tozeur, tunisia. parole chiave: deserto, geomorfosito, desertificazione, remote sensing, geoturismo, tozeur, tunisia. fig. 1 general location of the study area. localizzazione dell’area di studio. the region of tozeur is part of the atlas fold and thrust belt that extends from morocco over algeria right up to west tunisia. to the east of the tunisian atlas lies a north-south trending mountain range corresponding to the major fault zone that divides the atlas from the eastern sahel block. the region of tozeur belongs to the southern tunisian atlas in which are distinguished the gafsa zone in the north, characterised by a series of anticlinal east-west trending mountain ranges mainly composed of late mesozoic carbonate sediments, and the southern chotts trough region composed of a since late carboniferous subsiding sedimentary basin. the gafsa zone can be subdivided in the metlaoui chain, composed of an east-west trending tight anticline with an overturned forelimb and gently dipping (30°) backlimb, separated from the structurally similar “chaine des chotts” (east of tozeur) by a large box syncline (outtani et al., 1995). according to ben ferjani (1990) the “chaine des chotts” is located on a jurassic graben and corresponds fundamentally to the inversion of this inherited structure. the tectonic events, probably 225geomorphosites of tozeur ... active at least since middle pleistocene (since lower quaternary sediments are involved in the fold-thrust structures along the mountain fronts), have involved only the upper part of the sedimentary cover (the basal décollement would be identified in the cretaceous stratigraphic levels) that has been folded as a sheet upon the rigid basement (outtani et al., 1995; fakhraoui, 1999). subsidence in the chotts area occurred mainly during middle triassic-jurassic as a consequence of the separation between europe and africa and has continued during miocene-early pleistocene related to the compression associated with the atlas orogeny (burrolet, 1956; 1991; zargouni, 1984; 1985; 1986; swezey, 1996; patriat et al., 2003). many of the east-west oriented anticlines and synclines in the gafsa zone are cut by northwest striking right-lateral strike slip faults among which the gafsa fault and the negrine-tozeur fault have to be mentioned. the first is the most important one, having direction n 120°-130° (boutib & zargouni, 1998) and table 1 table of the identified and studied geomorphosites in the region of tozeur, distinguished by their genetic process and degree of scientific and didactic-divulgation interest for geotourism and geoconservation purposes. tabella dei geomorfositi identificati e studiati nella regione di tozeur, distinti in base al processo genetico e al livello di interesse scientifico e didattico-divulgativo ai fini del geoturismo e della geoconservazione. n° géomorphosite name province commune genetic age of level of process rocks interest 1 midès canyon tozeur tameghza ft cm *** 2 brikis anticline tozeur tameghza t cm * 3 grande cascade waterfall tozeur tameghza ft eoc ** 4 cascade de l’oasis waterfall tozeur tameghza ft eoc *** 5 en negueb canyon tozeur tameghza ft cup-eoc *** 6 chebika canyon and waterfall tozeur tameghza ft cup-ol *** 7 ancient mine of chouabin gafsa redeyef a eoc ** 8 thelja canyon gafsa metlaoui ft cup-ol *** 9 oued foum el khanga alluvial fan tozeur tameghza f q ** 10 oued mellah delta tozeur hamma f q * 11 ong el jemal aeolian sculpture tozeur el hamma du jerid m plio-q ** 12 el ghadayer yardangs tozeur nefta w q * 13 el ghadayer barchan dunes tozeur nefta w q * 14 chamsa nebkha fields tozeur tozeur-nefta wb q * 15 cardium lumachelle of jehim tozeur tozeur s q * 16 chaabet es sfa canyon tozeur degueche ft cup *** 17 sidi bou helal canyon tozeur degueche ft cup *** 18 ben nebhana canyon tozeur degueche ft cup ** 19 ben hamed canyon tozeur degueche ft cup *** 20 chott el jerid salt pan tozeur degueche ts q *** 21 corbeille de nefta oasis tozeur nefta a mio-plio ** the main genetic processes that are responsible for the formation of the geomorphosites are: ft = fluvial-tectonic; t = tectonic; a = anthropic; f = fluvial; m = meteoric ; w = aeolian ; wb = aeolian-biological ; s = sedimentary ; ts = tectonic-sedimentary. the age of the rocks : cm = middle cretaceous ; cup = upper cretaceous ; eoc = eocene ; ol = oligocene ; mio = miocene; plio = pliocene ; q = quaternary. level of interest : * = moderate ; ** = high ; *** = very high. 226 showing a lateral offset of 1 km, and seismological and stratigraphical data (chihi, 1979) together with the presence of thermal hot springs along the fault (coque, 1962) indicate that it is still active today. the oldest outcropping rocks of the region are of upper cretaceous age. at j. bou helal the outcropping sequence starts with the evaporites of beida containing rare ostracods of middle turonian, followed by a sequence of marls, whitish dolostones and limestones with abundant fossils such as foraminifers, ostracods, echinoids and ammonites of lower-middle coniacian age. this sequence is characterised by the presence of a hardground encrusted by oysters at the foot of the upper limestone levels (abdallah, 1987; abdallah et al., 1995). santonian starts with 40 m of greyish clays and marls (with santonian ostracods, echinoids and foraminifers) followed by ammonite containing limestone beds. campanian is characterised by greenish marls and marly limestones (with abundant fossil oysters) followed by white ammonite and echinoid-bearing limestone beds with clear evidence of emersion episodes. maastrichtian is dominated by massif and locally fossiliferous limestone beds dated on the basis of foraminifers, nautiloids and ostracods. at the end of cretaceous a short continental period interrupts sedimentation, immediately followed by dark gypsum-rich clays with phosphate levels deposited in a lagoonal basin (bensalem, 2002). this sequence has been grouped in the about 70 meters thick thelja formation that surmounts a silicified horizon (burrolet, 1956; chaabani, 1978). the economic phosphate deposits have been discovered in 1885 by philippe thomas at thelja gorge and underground mining started at metlaoui in 1899. the phosphate levels, alternated with bioturbated clays, belong to the ypresian and contain shark teeth and tortoise carapaces (sassi, 1974). phosphate levels are followed by two limestone beds with silex nodules (ypresian-lutetian) and carbonate-rich clays with gypsum levels (priabonian). during oligocene sedimentation becomes continental characterised by conglomerates with carbonate and clayey cement (fakhraoui et al., 1995; regaya et al., 2001). neogene is mainly characterised by coarse and fine sandy continental deposits dated from middle miocene up to villafranchian, this last constituted of sediments with cardium. the actual morphology has been defined during quaternary with the emplacement of several mostly continental deposits. in particular at least three generations of terraces have been recognised, all characterised by silty yellowish and more or less reddish sediments with intercalations of conglomerates and gypsum crusts. these terraced sediments cover unconformably the slightly tilted miocene sequences and have been dated respectively middle pleistocene, upper pleistocene and holocene (ben ouezdou et al., 1996). during holocene sediments of aeolian origin have been deposited, mostly captured in nebkhas and sometimes forming barchan dunes. also the sebkha soils of the chotts cover wide extensions of territory in the region of tozeur, characterised by fine wet sediments and brines in winter and mud cracked surfaces with salt and gypsum crusts in summer. finally the recent alluvium has to be mentioned, with more or less fine sediments depending on the distance from the jebels. among these transported sediments also the phosphate silts deriving from the mine industry can be classified, such as the ones of the oued el mellah. 3. methodology the geomorphosites of tozeur region have been chosen on a preliminary basis using existing geographical and geological maps and scientific papers on geology and geomorphology, but also tourist maps and guide-books. several field campaigns have been organised to identify and classify interesting geosites and geomorphosites, to verify the collected bibliographical data and to make detailed observations and gather further documentation (e.g. geological sketches, geomorphological processes, photographs). according to panizza m. (2001) a geomorphosite is “a landform with attributes which qualify it as a component of the cultural heritage”. on the field a sheet file has been compiled in which, together with the data of identification of the site (e.g. commune, locality, co-ordinates, altitude, etc.) also data on accessibility, visibility, geology and geomorphology, use and state of conservation are reported. an example of such a sheet file, adopted by our research team also in other north-african countries, is reported in figure 2. the identification, classification and graphical representation of the geomorphosite networks have been completed using remote sensing techniques. the satellite image interpretation has been performed using a legend in which the lithological units and the main morphologies have been classified. the choice of the legend classes has been focussed in particular on the geomorphological systems in which the chosen geomorphosites are located. the analysis of medium-infrared band combinations has allowed to recognise in a preliminary phase the different lithological units, by means of the creation of interpretation keys based on field surveys. the following data have then been analysed to characterise the morphology of the study area: lithology, tectonics, drainage pattern, land cover and topography. the use of satellite images has proven to be an ideal instrument for the recognition of the main landforms, guiding the field campaigns in a remarkable way. the almost complete absence of vegetation enhances the recognition of the different lithologies that can easily be revealed by their spectral response, and the distinction of topography has been enhanced introducing shadow analysis. the general structure of the area and the most important faults and alignments have been put in evidence by image elaboration techniques using directional filters associated with spectral analysis. remote sensing analysis has also been a powerful tool to study vast depositional systems such as the delta of oued el khanga, an inactive river fan, relic of much wetter periods, that flows into the chott el gharsa crossing transversally the ridge of el manndra-bliji. this fan has also been cut by neotectonic faults, clearly evidenced also by recent fluvial deviations, and visible using satellite images. the result of the remote sensing analysis, combined with terrain work, has enabled to compile the “map of geosites and geomorphosites of the region of tozeur” in which structural, lithological and geoj. de waele et al. 227geomorphosites of tozeur ... f ig . 2 e xa m p le o f sh e e t fil e u se d f o r th e s u rv e y, d e sc ri p ti o n a n d c la ss ifi c a ti o n o f th e g e o m o rp h o si te s. e se m p io d e lla s c h e d a d i r ile va m e n to , d e sc ri zi o n e e c la ss ifi c az io n e d e i g e o m o rf o si ti u ti liz za ta . 228 morphological data are resumed. the main purpose of these geomorphological training and research activities was to make the link between the single geomorphosites (intrinsic values) and the surrounding landscape (overall value) to form a complete perception of the importance of geological heritage in the region. in fact, only by means of a rigourous process of scientific awareness of this heritage it will become possible to create the basis for a conscient use in a context of sustainable development and valorisation through geotourism. this type of cultural tourism can be explicated very well in semi-arid and arid regions, because the landscape observation and analysis are favoured, and can become a good opportunity of economical growth. because of their easy perception (recognisability), their characteristic form (completeness), their state of conservation (exemplarity) and their effective possibility of visit (accessibility) geomorphosites can be defined ideal for valorisation and for geotourism (poli, 2003). a particularly significant and innovative aspect of this research is the proposal of networks, in which geomorphosites and geosites are linked by similar geomorphological processes, making their identification and recognition easier. this distinction in thematic networks of geosites and geomorphosites makes it also easier to define coherent actions of planning, valorisation and conservation. 4. geomorphosites for the moment a total of twenty-one geomorphosites have been chosen in the region of tozeur and are reported in table 1. these sites, in the prevision of their valorisation though geotourism, have been grouped in thematic circuits according to their geographical, geological, geomorphological and genetical characteristics. these circuits are: the "living desert", the "rocks and water", the "earth’s memory", the “phosphate route” and the “changing environment and climate” networks (fig.3). j. de waele et al. fig. 3 proposed network of geomorphosites organised in thematic itineraries related to prevalent genetic processes. rete di geomorfositi proposti organizzata per itinerari tematici legati ai processi genetici prevalenti. the "living desert" network is situated in the chott el gharsa region and can be reached departing from the ancient oasis of tozeur and following the road that leads to the famous ong el jmel natural sand sculpture. this network combines four geomorphosites: the nebkha fields of chamsa, the barchan dunes of el ghadayer, the yardangs of el ghadayer and the above mentioned ong el jmel geomorphosite. this network explains the products of aeolian processes in semiarid regions, the evolution of sand dunes, from young nebkha dunes over mature barchan dunes ending up with partially demolished dunes (yardangs). also the famous ong el jmel sand sculpture is inserted in this network, being an residual erosion form assuming the silhouette of a sitting dromedary, related to morphoselective meteoric processes. even though these single landforms are not easily readable on landsat images, because of their relatively small dimensions, on the most western side of the study area the greatest of the barchan dunes can be distinguished, reaching almost 150 meters of width. the "rocks and water" network, showing the landscape modelling and evolution through fluvial processes, is located in the chebika and tameghza mountains and combines seven geomorphosites: the canyons of midès and en negueb, the waterfalls of tameghza (“grande cascade” and “cascade de l’ oasis”), the anticline of brikis, the canyon, geological structures and waterfall of chebika (fig. 4) and the alluvial cone of oued foum el khanga (mamou, 1981). these seven sites represent the geomorphologic evolution of river profiles: water slowly erodes the outcropping rocks, accelerating the process during uplifting episodes (the tectonic evolution of the tameghza mountains can easily be explained showing the brikis anticline), and the alternation of hard and soft rocks causes differential erosion, formation of waterfalls and alternation of narrow canyon passages with larger riverbeds. at the end of the voyage the water flows out of the narrow gorges and enters the wide subsiding plains forming great alluvial fans. the satellite image, as said before, clearly puts in evidence the alluvial fan and the neotectonic movements, but also reveals wide and important structures such as chevrons, the smaller of which can also be easily distinguished on the field. close to tozeur, in the “chaine des chotts” mountains, the "earth’s memory" network is located comprising four canyons passing transversally through most of the cretaceous sedimentary sequence. in fact, the three canyons of sidi bou helal, ben nebhana and ben hamed cut the mountain range in its southern flank, while the chaabet es sfa canyon crosses the northern flank instead (ben ouezdou et al., 1996; gasmi, 1997). in these canyons the didascalic cretaceous sequence of this region can be observed in good exposure, showing many fossiliferous beds with ammonites, echinoids, oysters and gasteropods, allowing the visitors to go through 100 million years of earth’s history. also morphoselective meteoric processes have shaped interesting forms in the calcarenites, such as the mushroom-like rock sculptures in the ben hamed gorge (fig. 5). furthermore in some canyons of the southern flank ancient human settlements (roman dams and quarries, abandoned oasis, etc.) enrich these geomorphosites and the network in a whole. the “phosphate route” is of a more “human dimension” showing an abandoned underground phosphate mine near chouabin, the immense active phosphate mines (underground and open pit cultivation) and their environmental impact (tailings, sterile heaps, excavations, phosphate mud in the draining rivers, etc.) on the immediate environs but also at greater distance such as at the thelja gorge or at the oued el mellah delta. the analysis of satellite images clearly puts in evidence the dispersion of dust and phosphate muds, with a unique spectral response. finally the “changing environment and climate” network comprises three geomorphosites close to 229geomorphosites of tozeur ... fig. 4 eocene sedimentary sequence in almost vertical attitude in which the softer clay beds are in negative relief respect to the silicificated limestone beds. sequenza eocenica in giacitura subverticale nella quale gli strati argillosi teneri risultano più intaccate rispetto ai banchi silicizzati. tozeur: a small outcrop of quaternary littoral sediment very rich in cardium in the oasis of jehim testifying an ancient shoreline of the chott el djerid, the actual salt plain itself (ben ouezdou, 1999) and the corbeille of nefta with the ancient spring sites that are dried up due to overexploitation of the aquifer. 5. conclusions geoconservation and geotourism are widely used and accepted terms in europe and north-america, but are new concepts for tunisia. although geological heritage in tunisia is well known and many areas have been thoroughly studied by geologists, this geological and geomorphological knowledge is still restricted to few people, and should be diffused to a wider public. the author’s attempt is to explain the geological and geomorphological characteristics of the region of tozeur to the local people and to the visitors, enriching the already existing tourist offer with new themes of interest that are based on the geological and geomorphological resources that are particularly well represented in the region. in fact, many of the geomorphosites included in this paper are well-known tourist attractions, but the geological and geomorphological significance of these sites is never explained. the connection of several of these geomorphosites in circuits (or networks) has the purpose of explaining the geological and geomorphological evolution of these sites, giving a more educational explanation of sometimes complex and slowly developing phenomena. in the framework of the valorisation of the territory it is also important to make a link between natural processes and human activities: in many geomorphosites presented here also the human presence is clearly visible with archaeological remains (prehistoric graffiti, roman dams, abandoned oasis and settlements, etc.) or historical-technological curiosities (the “lezard rouge”, a tourist train along the suggestive ancient phosphate mine railtracks, abandoned and still operating phosphate mines, etc.). aside all these sites of geological or geomorphological interest many other important localities exist (e.g. the restored oasis or “corbeille” of nefta dried up due to human intervention and global change, museums, experimental date palm tree plantations etc.) and the integrated tourist development of all these natural and cultural resources can give new economic opportunities to this arid and semiarid region. acknowledgements this study has been carried out with the financial aid of the sardinian regional government in the framework of the project "identification, classification and valorisation of important landscapes and geosites in south tunisia” (responsible prof. felice di gregorio) (regional law n°19/1996). for the conceptual part of this work reference has been made to the national project cofin 2001-2003 “geomorhosites in the italian landscape”, national coordinator prof. sandra piacente, responsible of the local research unit prof. antonio ulzega and prof. felice di gregorio. the authors would like to thank mario panizza and sergio ginesu for their critical advice. references abdallah h. 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(1986) tectonique de l’atlas méridionale de tunisie. evolution géométrique et cinématique des structures en zone de cisaillement revue des sciences de la terra, mémoire iii, tunis, 304 pp. 232 j. de waele et al. imp.carveni& la salsa e la gurna di fondachello: evoluzione di un vulcano di fango e di uno stagno costiero all’estrema periferia nord-orientale dell’edificio vulcanico etneo (sicilia) pietro carveni 1, santo benfatto 2, rosanna maniscalco 1, maria salleo puntillo3 & giovanni sturiale 1 1 università di catania, dipartimento di scienze geologiche, corso italia 57, 95129 catania, italia, e-mail: carveni@unict.it 2 geologo, libero professionista, via san marco 91, 95047 paternò, catania, italia. 3 naturalista, via san marco 91, 95047 paternò, catania, italia. riassunto: carveni p., benfatto s., maniscalco r., salleo puntillo m. & sturiale g., la salsa e la gurna di fondachello: evoluzione di un vulcano di fango e di uno stagno costiero all’estrema periferia nord-orientale dell’edificio vulcanico etneo (sicilia). (it issn 03943356, 2006). sulla base di una rilettura critica della letteratura reperita, viene ricostruita l’evoluzione di un vulcano di fango e di uno stagno costiero ubicati al limite nord-orientale dell’etna, lungo la costa ionica. l’attività del vulcano di fango è iniziata in concomitanza del disastroso terremoto dell’11 gennaio 1693; una ripresa della sua attività viene segnalata nel dicembre 1795; questa fase cessa nel 1832; nel marzo del 1847 si ha una nuova fase eruttiva, che culmina con il crollo parziale dell’edificio. dai sopralluoghi risulta che non esiste più alcuna traccia dell’edificio pseudovulcanico, e l’unica attuale manifestazione di attività endogena rilevabile si limita ad emissioni di metano lungo un canale di drenaggio. sulla base di dati di letteratura e dal confronto di carte topografiche edite tra il 1895 e il 2000, viene ricostruita l’evoluzione di uno stagno costiero, la cui genesi potrebbe essere collegata a strutture tettoniche locali, la cui esistenza, in questa sede solo ipotizzata, potrebbe in futuro essere dimostrata tramite l'utilizzo di tecniche di prospezione geofisica. abstract: carveni p., benfatto s., maniscalco r., salleo puntillo m. & sturiale g., the salsa and the gurna near fondachello: evolution of a mud volcano and of a marsh on the farthest north-eastern periphery of mt. etna volcanic edifice (sicily). (it issn 0394-3356, 2006). evolution of a mud volcano and of a marsh are reconstructed in this paper; mud volcano (named salsa di fondachello) and marsh (named gurna di fondachello) were located on the farthest north-eastern periphery of mt. etna volcanic edifice, near the ionian coast. activity of mud volcano started on 1693, 11th january, during a disastrous earthquake; it was again active 1795 to 1832; his last activity started in 1847 march; in this occasion the building collapsed. today there is no trace of this mud volcano. only a little methane emission is the evidence of the endogenous activity. the evolution of a marsh is based on comparison of topographic maps, edited from 1895 to 2000, on bibliography dates and an analysis of existing literature and of a detailed geological-geomorphological survey. today the gurna is reduced to a small swamp and there isn't morphological evidence of the mud volcano; but, considering that the mud volcano has been active three times in historical times, its reactivation today could represent a danger for the surrounding inhabited area. parole chiave: zona etnea, vulcano di fango, stagno costiero, geomorfologia. keywords: mt. etna volcano zone, mud volcano, marsh, geomorphology. il quaternario italian journal of quaternary sciences 19(1), 2006 67-76 1. introduzione all’estrema periferia nord-orientale dell’edificio vulcanico etneo, a piccola distanza dalla costa ionica, nei pressi dell’abitato di fondachello, frazione del comune di mascali, si trova un piccolo stagno costiero, conosciuto un tempo col nome di gurna di pane e vino, attualmente come gurna di fondachello. lungo la sponda sud-orientale dello stagno si formò, in occasione del disastroso terremoto dell’11 gennaio 1693, un vulcano di fango, denominato salsa di fondachello; esso si riattivò nel dicembre del 1795 e rimase in eruzione fino al 1832; una breve ripresa dell’attività, che si concluse con il parziale crollo dell’edificio, fu registrata nel 1847. nel presente articolo, sulla base di una rilettura critica dei dati di letteratura, dell’analisi di aerofotografie e di carte topografiche, e di rilievi geologico-geomorfologici di dettaglio, si effettua la ricostruzione dell’evoluzione della salsa e della gurna di fondachello. con il termine vulcani di fango si indicano gli edifici che si formano in seguito a manifestazioni pseudovulcaniche, consistenti prevalentemente in emissioni di fango, la cui origine è legata all'esistenza nel sottosuolo di gas sotto pressione, i quali tendono a migrare verso la superficie attraverso rocce permeabili e/o discontinuità litologiche e/o strutturali, trascinando nel loro movimento acqua, idrocarburi, fango e frammenti litici. la genesi dei fanghi è da attribuire al passaggio di acqua attraverso formazioni argillose, con conseguente stemperatura delle particelle d'argilla; a seconda della densità del fango emesso, si vengono a formare edifici troncoconici dalle pendici più o meno inclinate e con cavità craterica alla sommità, colate di fango o conche subcircolari piene d’acqua; in genere le acque contengono soluzioni saline, che, precipitando, formano carat68 p. carveni et al. teristiche incrostazioni, da cui il nome di salinelle o salse con cui questi edifici vengono indicati in alcune località. si tratta di morfologie effimere, instabili, che in brevi periodi possono subire profonde trasformazioni, sia in seguito a nuove emissioni, sia a causa degli agenti atmosferici: trattandosi infatti di edifici costituiti prevalentemente da fango, l'insolazione ne provoca la disidratazione, con conseguente formazione di fratture di disseccamento, all'interno delle quali penetrano le acque piovane dando luogo a spinti fenomeni erosivi. per la zona sud-occidentale dell'etna, la risalita di fluidi fangosi è stata recentemente riferita all'esistenza di strutture tettoniche (la manna & carnazzo, 2000) o a condotti vulcanici (carveni et al., 2001). nell'area in esame, mancando qualsiasi evidenza di apparati vulcanici, la risalita dei fluidi potrebbe essere favorita dalla presenza di strutture tettoniche sepolte da alluvioni recenti, la cui esistenza è in questa sede solo ipotizzata, ma che potrebbe essere dimostrata in ricerche future, tramite l'utilizzo di tecniche di prospezione geofisica. la genesi degli stagni costieri è collegata in genere all’esistenza di un mare poco profondo e una costa ricca di insenature in fase di sommersione; è importante la vicinanza di foci fluviali che forniscano cospicue quantità di sabbie e/o ghiaie. in queste condizioni è facile che si formi una barra costiera a piccola distanza dalla costa, in corrispondenza di un’insenatura; la barra può evolvere trasformandosi in tombolo, e la baia diventa una laguna o uno stagno costiero. in altri casi la formazione di uno stagno costiero è geneticamente collegata all’attività di faglie, come verrà dimostrato nel presente articolo. 2. quadro geologico-strutturale dell’area etnea la zona in studio si trova all’estrema periferia nord-orientale dell’edificio vulcanico etneo, lungo la costa ionica. l’etna, con la sua altitudine di poco superiore a 3.300 metri e col diametro massimo di 44 chilometri, è il maggiore vulcano attivo del continente europeo. esso è uno stratovulcano complesso, risultante dalla sovrapposizione dei materiali emessi da diversi centri eruttivi, poggianti su un basamento in parte alloctono, formato da rocce di età compresa tra il cretaceo ed il pleistocene (romano et al., 1979). l’edificio vulcanico etneo sorge al limite tra diversi domini strutturali della sicilia orientale (fig. 1), dove la crosta oceanica ionica e la crosta continentale dell’avampaese ibleo si immergono sotto il fronte dell’orogene appenninico-maghrebide (finetti et al., 1996). l’avampaese ibleo costituisce il margine della placca africana (burollet et al., 1978), zona stabile verso cui convergono le falde neogeniche dell’orogene appenninico-maghrebide; esso è costituito da una potente successione prevalentemente carbonatica compresa tra il trias e il pleistocene medio, con intercalati prodotti effusivi basici cretacei, miocenici e pliopleistocenici, la cui risalita è stata favorita da intense fasi tettoniche distensive (cristofolini, 1966; di grande, 1967; 1969; 1972; patacca et al., 1979; carbone et al., 1982; lentini et al., 1986; carbone et al., 1987; carveni et al., 1991 a; 1991 b; 1993; carveni & sturiale, 1999). l’avampaese ibleo confina ad oriente con la crosta oceanica del bacino ionico (finetti, 1982) tramite la scarpata ibleo-maltese, originata da un sistema di faglie normali a gradinata (finetti & morelli, 1972), il cui prolungamento verso settentrione interseca il fianco orientale dell’edificio etneo (lo giudice et al., 1982). il tratto siciliano dell’orogene appenninicomaghrebide si è formato in seguito all’accavallamento della catena kabilo-calabride, costituita da falde di basamento cristallino interessate da metamorfismo ercinico con resti dell’originaria copertura sedimentaria mesocenozoica, sulla catena appenninico-maghrebide, edificio orogenico formato dalla sovrapposizione di falde sud-vergenti (finetti et al., 1996). sulla genesi del vulcano e sul quadro strutturale sono reperibili in letteratura alcuni modelli: 1) intersezione tra due importanti lineamenti strutturali: la scarpata ibleo-maltese e il sistema di faglie messina fiumefreddo (o g n i b e n et al., 1975; mcguire et al., 1997); 2) risultato di una tettonica estensionale che ha portato alla formazione di un graben in corrispondenza dell’attuale piana di catania (di geronimo et al., 1978); 3) processi di rifting tra il blocco maltese siciliano ed il bacino ionico (gillot et al., 1994; continisio et al., 1997); 4) deformazione al footwall di una faglia normale appartenente al sistema distensivo siculo-calabro ad andamento wnw-ese (monaco et al., 1997); 5) risalita di magmi dal mantello a causa di un hot spot (tanguy et al., 1997); 6) roll-back di una porzione di litosfera subdotta al di sotto del mar tirreno (gvirtzman & nur, 1999). a causa di un sollevamento regionale, l’attività eruttiva dell’etna, inizialmente sottomarina e fissurale, è diventata in seguito subaerea ed a carattere centrale; figura 1 schema strutturale della sicilia (da finetti et al., 1996). cs) catena sicana; cam) catena appenninicomaghrebide; ckc) catena kabilo-calabride; ai) avampaese ibleo; e) edificio vulcanico etneo; sim) scarpata ibleo-maltese; smf) sistema di faglie messina-fiumefreddo; il quadrato indicato dalla freccia corrisponde alla zona in studio. structural sketch of sicily (after finetti et al., 1996). cs) sicana chain; cam) apennine-maghrebian chain; ckc) kabilocalabrian chain; ai) iblean foreland; e) mount etna volcano; sim) iblean-malta escarpment; smf) messina-fiumefreddo fault system; narrow indicates position of studied area. ciò ha causato una variazione nel meccanismo di risalita dei magmi, con conseguente cambiamento del chimismo: da lave subalcaline si è passati a prodotti più o meno differenziati della serie alcalino-sodica (romano, 1982). carapezza (1962), nel tentativo di determinare una relazione tra la tettonica regionale e le zone di minore resistenza dell’etna, identifica un rift lungo il fianco orientale dell’edificio vulcanico. ma r c h e s i n i et al. (1964) riconoscono quattro principali allineamenti tettonici, con direzioni n-s, ene-wsw, ne-sw e nw-se. frazzetta & romano (1978) identificano due allineamenti alimentatori preferenziali per le aree ad alta probabilità di eruzioni: una nel settore circolare compreso tra ne-sw e enewsw, la seconda con direzione nnw-sse. lo gi u d i c e et al. (1982) riconoscono nell'area etnea e nelle zone circostanti varie direttrici di faglie: le più importanti hanno direzione n 60° e, n 30° e, n 15° w e n 60° w. kieffer (1983 a; 1983 b) ipotizza l’esistenza di scivolamenti gravitativi di parte del versante orientale dell’edificio vulcanico, ed attribuisce il fenomeno alla ripetuta intrusione di magma attraverso un rift di ne ed un rift meridionale. l’ipotesi di uno scivolamento gravitativo viene ripresa da azzaro et al. (1989) e da neri et al. (1991). borgia et al. (1992), sulla base dei risultati ottenuti da ferrari et al. (1991) sui dicchi affioranti nella valle del bove, ipotizzano uno spreading radiale del substrato dell’etna verso se. lo giudice & rasà (1992) ritengono invece che si tratti di movimenti puramente gravitativi, che provocano lo scivolamento verso sse della porzione dell’edificio etneo delimitata a settentrione dalla faglia della pernicana (fig. 2: fp) e dal rift di ne (fig. 2: rne), e a sw dalle faglie di mascalucia e trecastagni (fig. 2: fma e ft). la documentazione storica relativa ai terremoti avvenuti sul basso versante orientale etneo negli ultimi due secoli e l’influenza dei movimenti tettonici sulla morfologia sono state analizzate in una serie di articoli (adorni & carveni 1993 a; 1993 69la salsa e la gurna di fondachello ... b; carveni & bella, 1994; bella et al., 1996; carveni et al., 1996; 1997; gresta et al., 1997; carveni et al., 2004; 2005 a; 2005 b). dall’analisi dei sistemi di faglie che nel pleistocene sono stati attivi in sicilia orientale, sulla base di dati geologico-strutturali e morfologici e dell’analisi di sezioni sismiche a mare, monaco & tortorici (1995) e monaco et al. (1995; 1997) distinguono un sistema acireale – sant’alfio (formato da faglie normali figura 2 ubicazione dell'area in studio e delle più importanti strutture tettoniche del versante orientale dell'etna su base dem (pareschi et. al., 1999). faglie: ff) faglia di fondachello; fm) faglia di moscarello; fma) faglia di mascalucia; fmg) faglia milo – giarre; fmr) faglia macchia – riposto; fms) faglia macchia – stazzo; fp) faglia della pernicana; fpvc) faglia praiola – villa calanna; frn) faglia della ripa della naca; frp) faglia della ripa di piscio; fsl) faglia di san leonardello; ft) faglia di trecastagni; ftm) faglia del torrente minissale; ftma) faglia del torrente macchia; sp) sistema di piedimonte. centri abitati: a) acireale; ct) catania; fi) fiumefreddo; fo) fondachello; g) giarre; ma) mascali; m) mascalucia; n) nicolosi; r) riposto; s) stazzo; sa) sant’alfio; t) trecastagni. cc) cratere centrale; rne) rift di ne. location of studied area and of the main tectonic structures of eastern flank of mt. etna volcano; dem after pareschi et. al. (1999): ff) fondachello fault; fm) moscarello fault; fma) mascalucia fault; fmg) milo – giarre fault; fmr) macchia – riposto fault; fms) macchia – stazzo fault; fp) pernicana fault; fpvc) praiola – villa calanna fault; frn) ripa della naca fault; frp) ripa di piscio fault; fsl) san leonardello fault; ft) trecastagni fault; ftm) torrente minissale fault; ftma) torrente macchia fault; sp) piedimonte system. towns: a) acireale; ct) catania; fi) fiumefreddo; fo) fondachello; g) giarre; m) mascalucia; ma) mascali; n) nicolosi; r) riposto; s) stazzo; sa) sant’alfio; t) trecastagni. cc) central crater; rne) ne rift. 70 con componente trascorrente destra nnw-sse) e un sistema di piedimonte (faglie normali e fratture d’estensione nne-ssw); entrambi i sistemi, associati ad un’estensione wnw-ese, formano scarpate di età suprapleistocenico-olocenica, le quali esercitano un controllo sulla topografia e sul reticolo idrografico. con uno studio prevalentemente geomorfologico, basato sull’analisi di aerofotografie, di carte topografiche, di carte nautiche e di cartografia su supporti magnetici, è stato ipotizzato il sistema di faglie giardini – mascali (carveni et al., 2005 a), che potrebbe condizionare la morfologia del sito in studio. 3. lineamenti geologici dell’area nell’area studiata in dettaglio (fig. 3) affiorano prodotti sedimentari e vulcanici di età compresa tra il pleistocene inferiore e l’attuale; la serie stratigrafica affiorante nell’area è costituita, dal basso, dalle seguenti formazioni: 1) calcareniti bianco-giallastre infrapleistoceniche: affiorano sui fianchi della collinetta di serra san biagio, a ne di fiumefreddo di sicilia; si tratta di calcareniti in banchi, con spessore in affioramento di circa 30 metri (fig. 3: 7); sono riferibili regionalmente alle calcareniti bianco-giallastre (d i g r a n d e , 1967; 1969; 1972); 2) argille grigio-azzurre infrapleistoceniche: affiorano lungo un horst con direzione ne-sw a settentrione di fondachello (fig. 3: 6); corrispondono regionalmente alle argille grigio-azzurre (d i grande, 1967; 1969; 1972); 3) piroclastiti dell’unità del trifoglietto affiorano nella parte sud-occidentale della zona in studio (fig. 3: 5); si tratta di piroclastiti di colore bruno giallastro riferibili ai termini basali dell’unità del trifoglietto, la cui attività è iniziata circa 100.000 anni fa (romano, 1982); 4) colate laviche (fig. 3: 4) provenienti dai centri eruttivi del mongibello antico (romano et al., 1979; romano, 1982); 5) alluvioni recenti: sono state deposte dall’alcantara e da altri corsi d’acqua che drenano la zona (fig. 3: 3); 6) la zona è stata interessata da alcune colate laviche datate (fig. 3: 2), relative all’attività del mongibello recente (romano et al., 1979; romano, 1982); 7) alluvioni e depositi di spiaggia attuali chiudono la serie stratigrafica (fig. 3: 1). 4. evoluzione della gurna di fondachello per lo sviluppo di un lago costiero è necessario che vi siano: 1) una zona costiera in fase di sommersione, ricca di insenature; 2) un mare poco profondo; 3) foci fluviali, che forniscano cospicue quantità di sabbie e/o ghiaie. in queste condizioni, è facile che il moto ondoso e/o le correnti marine formino una barra a piccola distanza dalla costa, di fronte ad un’insenatura; se la barra evolve trasformandosi in tombolo, la baia diventa una laguna o uno stagno costiero. le caratteristiche peculiari di uno stagno costiero sono: 1) sponde basse; 2) scarsa profondità; 3) forma allungata parallelamente alla costa. l’aspetto presentato dalla gurna nelle carte più antiche reperite è in effetti quello tipico degli stagni costieri: essa potrebbe essersi formata a causa di un accumulo di sabbie e ghiaie deposte dal moto ondoso, figura 3 schema geologico: 1) alluvioni e depositi di spiaggia attuali; 2) colate laviche del mongibello recente; 3) alluvioni recenti; 4) colate laviche dei centri eruttivi del mongibello antico; 5) piroclastiti dell’unità del trifoglietto; 6) argille marnose azzurre infrapleistoceniche; 7) calcareniti infrapleistoceniche. geological sketch of studied area: 1) present day alluvium and shoreline deposits; 2) lavas flows from the eruptive centres of mongibello recente 3) recent alluvium; 4) lavas flows from the eruptive centres of mongibello antico; 5) pyroclastics from trifoglietto unit; 6) early pleistocene bluish marly clays; 7) early pleistocene calcarenites. p. carveni et al. 71 ma non sono rispettate le altre condizioni: non vi sono insenature e i corsi d’acqua che sboccano nelle immediate vicinanze, il torrente fiumefreddo e il torrente delle forche hanno scarsa portata solida; inoltre la profondità del mare aumenta repentinamente con la lontananza dalla costa (istituto idrografico della marina, 2001). per questi motivi, i dati provenienti dalla ricerca hanno fatto scartare l’ipotesi di una genesi sedimentaria del bacino e hanno fatto ipotizzare un'origine legata a cause tettoniche. recupero (1815), nel suo lavoro pubblicato postumo, e redatto precedentemente al 1778, descrive una palude costiera, chiamata azanetto o cottone, ubicata tra la piana di mascali ed il mare; si può ipotizzare che nel xviii secolo il bacino della gurna fosse più grande, e che in seguito, per fenomeni di interramento e/o legati alla siccità e/o ad opere di bonifica, la sua estensione sia diminuita, dando luogo ad una serie di bacini di minori dimensioni. galvagni (1839), in uno studio sulle paludi della sicilia, ne descrive tre esistenti nella zona di mascali: urna di pane e vino, estesa circa una salma (3,43 ettari); auzini, estesa circa due salme (6,86 ettari) e già da alcuni anni bonificata; azzanetto, molto prossima alla spiaggia. secondo mercurio (1847) tra il 1839 e il 1846, a causa di un lungo periodo di siccità, le sorgenti gebbia, fico e panevino, che alimentavano la gurna di fondachello, si estinsero, e il bacino si prosciugò; nell'ottobre 1846, con la ripresa delle piogge, le sorgenti si riattivarono e il bacino lacustre tornò a riempirsi d'acqua. sulla più antica carta topografica da noi reperita (i.g.m., 1895) la gurna ha forma grossolanamente triangolare, con il lato maggiore in direzione ne-sw, lungo la scarpata della faglia di fondachello, una superficie di circa 8.300 metri quadrati; essa risulta alimentata da una serie di sorgenti a settentrione (sorgenti panevino), allineate in direzione nw-se, lungo un presunto piano di faglia, evidenziato dall’allineamento delle sorgenti e dall’andamento delle isoipse, da due sorgenti all’estremità sud-orientale (sorgenti gebbia e fico) e da una sorgente ubicata ad occidente (sorgente di case decime) (fig. 4 a); lo sbocco al mare avveniva per tracimazione. nelle carte del 1938 (i.g.m., 1938) la gurna si è ridotta ad una zona paludosa, alimentata dalle sorgenti gebbia e fico; le sorgenti panevino sono estinte e la loro zona è occupata da acquitrini; la sorgente di case decime è ancora alimentata, e una nuova sorgente si è formata ad oriente del vecchio bacino della gurna; le zone acquitrinose sono drenate da canali (fig. 4 b). il panorama cambia nelle carte del 1967 (i.g.m., 1967): con la dicitura la gurna viene indicato il canale che raccoglie le acque delle sorgenti gebbia e fico, e nel quale confluiscono altri canali; sulla carta non c’è traccia di zone paludose (fig. 4 c). la situazione si presenta praticamente identica nel 1974 (i.g.m., 1974), mentre nelle carte del 1987 (r e g i o n e s i c i l i a n a , 1987) e del 2000 (p r o v i n c i a regionale di catania, 2000) è riportato solamente il canale che convoglia le acque delle sorgenti gebbia e fico e non gli altri (fig. 4 d). la genesi della gurna e degli altri bacini locali potrebbe essere attribuita, nel contesto del sollevamento generale della zona etnea, ad un abbassamento differenziale di una parte della pianura costiera limitata ad oriente dalla presunta faglia di fondachello. 5. evoluzione della salsa di fondachello secondo boccone (in alibrandi, 1985), in occasione del disastroso terremoto dell’11 gennaio 1693 si formò, tra la costa del mar jonio e la gurna di fondachello, una fontana di acqua fangosa che raggiungeva i 32 metri di altezza (fig. 5, d). recupero (1815), nella sua accurata descrizione dei luoghi, esplorati prima del 1778, non fa alcuna menzione del vulcano di fango: se ne deduce che gli agenti atmosferici avevano del tutto eroso tale edificio, e tra gli abitanti del luogo non se ne era conservata la memoria. nel corso di una notte non precisata del dicembre 1795, nei dintorni di fondachello furono avvertite numerose scosse sismiche, accompagnate da rumori provenienti dal sottosuolo (mercurio, 1847); chi all'alba si recò sulla sponda della gurna vide che sull'orlo sudorientale del bacino si era formata una fontana di acqua fangosa alta fino a 6-7 metri. l'intensità del fenomeno diminuì gradatamente e, tre mesi dopo l’inizio dell’attività, dall'orlo del cratere dell'edificio che nel frattempo si era formato per l’accumulo di fango, sgorgava tranquillamente un'acqua fangosa ricca di gas, che si riversava, stemperandosi, nel bacino lacustre. nel 1832, quando questo periodo di attività cessò, il vulcano di fango era alto 3,6 metri rispetto al livello dell'acqua della gurna, e 6,1 metri rispetto al livello del mare (fig. 5, c). nel marzo del 1847 vi fu una ripresa dell'emissione di acqua fangosa, preceduta da una serie di scosse sismiche (tab. 1); tre di esse, più forti delle precedenti, si verificarono rispettivamente durante la notte tra il 25 e il 26 marzo, all'alba del 26 marzo, e l’ultima, che fu avvertita anche a catania, alle 19,30 dello stesso giorno. durante la notte del 9 aprile 1847 gli abitanti di fondachello udirono un'esplosione; il mattino successivo si vide che la base orientale del vulcano di fango era sprofondata, e si era formata una cavità ellittica che andava lentamente riempiendosi di acqua gorgogliante a causa del gas di cui era ricca; l'asse maggiore con direzione e-w era lungo 18,6 metri, l’asse minore 13,4 metri. il 10 maggio 1847 gli assi giunsero a 23 e 19,3 metri, mentre il livello dell'acqua si trovava a 4,8 metri dall'orlo delle sponde e la profondità del bacino, misurata in diversi punti, era di circa 4 metri. lungo le sponde del bacino mercurio (1847) riconobbe, dall'alto in basso, 4 diversi strati (fig. 6): a) il più alto, con spessore variabile da 1,95 metri nel punto più vicino ai resti del cono del vulcano di fango a 0,3 metri sulla sponda opposta, era formato dal fango emesso nel periodo di attività 1795-1832; b) il secondo strato era costituito da sabbie e ciottoli, presumibile deposito di spiaggia, con spessore costante di 0,3 metri; c) il terzo, composto da fango, presentava uno spessore massimo di 1,3 metri nei pressi del vulcanetto e si riduceva a zero all'altra estremità del bacino; a nostro avviso questo strato di fango è da attribuirsi all'attività iniziata in concomitanza con il terremoto dell'11 gennaio 1693; d) infine affiorava uno strato di paleosuolo con sabbia e la salsa e la gurna di fondachello ... 72 ciottoli. la superficie dell'acqua nel bacino di neo formazione si trovava a 1,6 metri al di sotto del livello del mare e a 1,1 metri al di sotto del livello dell'acqua della gurna; le sue acque erano continuamente agitate a causa della grande quantità di gas che si sprigionava, in particolare da due punti, uno nelle immediate vicinanze del condotto del vulcano di fango, l'altro al punto opposto dell'ellisse. attualmente non vi è alcuna traccia del vulcano di fango, e l’unica manifestazione di origine endogena riscontrata nel territorio è un’emissione di metano lungo un canale di drenaggio (d’alessandro et al., 1997); questo punto di emissione, comunque, non corrisponde all’ubicazione attribuibile alla salsa di fondachello in base ai dati di letteratura: infatti, secondo mercurio figura 4 topografia della zona della gurna di fondachello: a) sulla base del quadrante “riposto”, i.g.m., 1895; b) sulla base della tavoletta “fiumefreddo di sicilia”, i.g.m., 1938; c) sulla base della tavoletta “fiumefreddo di sicilia”, i.g.m., 1967; d) sulla base della carta tecnica della provincia regionale di catania, scala 1:10.000, sezione 625030. topography of gurna di fondachello zone: a) based on “riposto” 1:50,000 scale map edited by italian military geographic institute in 1895; b) , based on “fiumefreddo di sicilia” 1:25,000 scale map edited by italian military geographic institute in 1938; c) based on “fiumefreddo di sicilia” 1:25,000 scale map edited by italian military geographic institute in 1967; d) based on provincia regionale di catania 1:10,000 scale map, 625030 section. p. carveni et al. (1847) il vulcano di fango sorgeva sulla sponda sudorientale della gurna (fig. 4 a), mentre le emissioni gassose oggi osservabili si trovano in corrispondenza della sponda occidentale di ciò che resta del bacino lacustre (fig. 4 d). 5. conclusioni sulla base di un’analisi della scarsa letteratura esistente e di un dettagliato studio geologico-geomorfologico, si ricava che: 73 fig. 5 ricostruzione morfologica della gurna dal momento della sua formazione e della salsa di fondachello dal 1693 ai giorni nostri. morphological evolution of gurna marsh from the moment of its formation and of salsa di fondachello mud volcano from 1693 to present time. la salsa e la gurna di fondachello ... 1) il basso versante nord-orientale dell’etna è stato interessato dall’attività di faglie dirette, le quali, nell’ambito di un generale sollevamento dell’edificio etneo, hanno provocato una serie di abbassamenti localizzati, con conseguenti fenomeni di subsidenza; queste faglie hanno agito sull’andamento della linea di costa e sul reticolo idrografico, causando la formazione di alcuni stagni costieri, attualmente in parte bonificati, in parte in via di estinzione, tra i quali il più importante è la gurna di fondachello; 2) la salsa di fondachello era un vulcano di fango formatosi in occasione del disastroso terremoto dell’11 gennaio 1693; poiché esso non viene né descritto né nominato da recupero (1815), il quale esplorò la zona nella seconda metà del diciottesimo secolo, si può ipotizzare che in quel periodo non se ne conservava alcuna traccia; 3) l’attività della salsa riprese nel dicembre del 1795, accompagnata da scosse sismiche; le emissioni di fango durarono, in fase decrescente, fino al 1832; 4) una nuova fase parossistica (marzo – aprile 1847) fu accompagnata da uno sciame di sismi, l’ultimo dei quali talmente forte da essere avvertito fino a catania; si trattò chiaramente non di un sisma legato all’attività della salsa di fondachello, ma al contrario fu il movimento tettonico ad influenzare l’evoluzione del vulcano di fango. si ipotizza che l’origine dei laghi costieri della zona e del vulcano di fango sia collegata alla tettonica locale: all’attività della faglia di fondachello si potrebbe addebitare lo sbarramento che ha provocato la nascita dei laghi costieri e l’apertura della frattura attraverso la quale è avvenuta la fuoriuscita del fango della salsa di fondachello. attualmente, mentre della gurna rimane solo una piccola zona acquitrinosa, non si hanno tracce dell’ubicazione della salsa: poiché essa stava sull’orlo sud orientale della gurna, la sua ubicazione non può corrispondere a quella del punto di emissione di gas (confronta le figure 4a e 4d). in considerazione del fatto che il vulcano di fango è stato attivo almeno tre volte, e che la zona di fondachello sta vivendo una fase di forte urbanizzazione, nonostante i vincoli imposti quale sito di interesse comunitario sic (ita070003 – la gurna) e zona di protezione speciale, si ritiene che una sua non improbabile riattivazione potrebbe causare ingenti danni se non si attuassero gli strumenti di pianificazione territoriale a tutela del geosito ed area naturalistica protetta de la gurna. studio effettuato con i fondi del m.i.u.r., nell’ambito delle ricerche morfodinamica di zone vulcaniche e/o sismicamente attive morfodinamica di zone costiere sismicamente attive, responsabile pietro carveni. 74 tabella 1 data fenomeni zona di osservazione attività della salsa terremoto disastroso nascita del vulcano di fango, 1693 gen. 11 (xi scala mercalli) sicilia orientale. con emissione di acqua fangosa fino a 32 metri di altezza. numerose scosse durante nelle contrade attorno emissione di acqua fangosa 1795 dic. tutta la notte, accompagnate alla gurna. fino a 6-7 metri di altezza. da rombi sotterranei. 1847 mar. 25 scosse nelle contrade attorno ripresa dell’attività. alla gurna. 1847 mar. 26, scosse nelle contrade attorno nessuna h 06,15 alla gurna. 1847 mar. 26, h 19,30 scosse fino a catania. nessuna nelle contrade attorno crollo del fianco orientale del 1847 apr. 9 esplosione alla gurna. vulcano di fango ed intensa emissione di acqua ricca di gas. figura 6 ricostruzione della stratigrafia dei depositi attorno al vulcano di fango, da mercurio, 1847. stratigraphy of deposits around mud volcano, after mercurio, 1847. p. carveni et al. ringraziamenti ringraziamo il prof. italo di geronimo per la lettura critica del manoscritto, e i referees per gli utili e costruttivi consigli. lavori citati adorni g. & carveni p. 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(1997) evolution of the mount etna magma: constraints on present feeding system and eruptive mechanism. jour. volc. geot. res., 75, 221-250. 76 ms. ricevuto il 3 maggio 2006 testo definitivo ricevuto il 12 settembre 2006 ms. received: may 3, 2006 final text received:september 12, 2006 p. carveni et al. imp.carveni&solleva sollevamenti a grande scala e conseguenti fenomeni gravitativi: l’esempio del versante orientale dell’etna (sicilia) pietro carveni 1, domenico bella 2, santo benfatto3, rosanna maniscalco1, maria salleo puntillo4 & giovanni sturiale1 1università di catania, dipartimento di scienze geologiche, corso italia 57 95129 catania, italia; e.mail: carveni@unict.it; 2geologo, centro studi sull’ambiente, via nino martoglio 13, 95024 acireale, catania, italia; 3geologo, libero professionista, via san marco 91, 95047 paternò, catania, italia; 4naturalista, via san marco 91, 95047 paternò, catania, italia. riassunto: carveni p., bella d., benfatto s., maniscalco r., salleo puntillo m. & sturiale g., sollevamenti a grande scala e conseguenti fenomeni gravitativi: l’esempio del versante orientale dell’etna. (it issn 0394-3356, 2005). nell’ambito di un generale sollevamento che interessa la costa orientale della sicilia, un settore dell’edificio vulcanico etneo è caratterizzato da fenomeni di abbassamento; le zone interessate dai due fenomeni contrastanti sono facilmente riconoscibili lungo la costa. sulla base di una rilettura critica della letteratura reperita, cui hanno fatto seguito rilievi geologico-geomorfologici di dettaglio, sono state ricostruite le variazioni relative del livello marino medio in alcuni siti ubicati lungo la costa orientale della sicilia, tra torre archirafi a settentrione e la baia di ògnina (catania) a meridione; i dati evidenziano movimenti differenziali con un arretramento della linea di costa nella zona tra torre archirafi e stazzo ed un innalzamento della costa tra aci castello e catania. per meglio caratterizzare i fenomeni di abbassamento, è stata studiata la sismicità di tre importanti faglie con direzione nnw-sse per il periodo compreso tra il 1805 e il 1989, mediante la ricostruzione dei campi macrosismici dei terremoti più significativi relativi alle strutture in oggetto; l’entità complessiva del movimento lungo i piani di faglia durante il periodo considerato è la somma delle dislocazioni avvenute in relazione ai sismi e di fenomeni di creep asismico; dai dati ottenuti risulta che le dislocazioni lungo i singoli piani di faglia considerati sono compresi tra 0,2 e 1,5 cm/anno; l’analisi delle curve isosisme ha fatto ipotizzare la presenza di faglie sinora non riconosciute, ma la cui esistenza è ipotizzabile anche su basi morfologiche e geofisiche. i risultati sono in accordo con i dati di letteratura relativi alla dinamica del versante orientale etneo, il quale risulta soggetto ad un progressivo scivolamento verso ese tramite lo svincolo costituito dalla faglia della pernicana a settentrione e le faglie di mascalucia e di trecastagni a se. abstract: carveni p., bella d., benfatto s., maniscalco r., salleo puntillo m. & sturiale g., regional uplift and consequent gravitational phenomena: the example of eastern slope of mt etna volcano. (it issn 0394-3356, 2005). mt. etna is the largest active volcano in europe; it is a volcanic complex, formed by products of several eruptive centres, which were active in different times. it is located on the margin of two main structural domains of eastern sicily: the hyblaean foreland and the apennine-maghrebian chain. the hyblaean foreland belongs to the northern part of the african plate; it is formed by a very thick triassic to pleistocene carbonate succession, with several intercalations of mafic volcanic rocks. the apennine-maghrebian chain consists of several thrust sheets, made up of structural units derived from different palaeogeographical domains; they were overthrusted upon each other during several tectonic phases from eocene to pleistocene. eastern sicily is interested by a general uplift but a sector of the etna volcanic building is characterized by lowering. along the ionian sea coast we recognized uplift movements between catania and aci castello and subsidence between stazzo and torre archirafi. the lower eastern slope of mt. etna volcano is a high seismic hazard zone; it is characterized by superficial hypocentres earthquakes with little mesoseismic area. information is available about earthquakes which happened in this region during the last two centuries. the seismic activity of three faults was studied in the time span between 1805 and 1989. tectonic movements also caused very important landscape variations, like waterfalls and river piracies. our studies demonstrate that the subsidence along the coast is the result of the total amount of displacement measured along the fault planes (moscarello, san leonardello and macchia-stazzo faults). the analysis of the isoseismal lines suggests the presence of not yet known faults, whose existence is also testified on morphological and geophysical bases. the results of this paper agree with the data of literature related to the dynamics of the eastern slope of mt. etna; it is subject to a progressive sliding toward ese. parole chiave: versante orientale del monte etna, tettonica, geomorfologia, variazioni della linea di costa. keywords: eastern slope of mt. etna volcano, tectonics, geomorphology, changes of coast line. il quaternario italian journal of quaternary sciences 18(2), 2005 157-171 1. introduzione e scopo del lavoro il monte etna è un vulcano composito, localizzato lungo la costa orientale della sicilia. il suo basso versante orientale è interessato da un fascio di faglie normali con direzione generale nnwsse, con movimento prevalentemente verticale, la cui attività, che si manifesta attraverso terremoti con ipocentro superficiale e fenomeni di creep asismico, ha dato luogo ad una fossa tettonica conosciuta come graben di san leonardello. queste faglie hanno provocato variazioni del paesaggio, influenzando l’andamento della rete drenante e della linea di costa (platania, 1905 a; 1922; adorni & 158 p. carveni et al. carveni, 1993 a; 1993 b; carveni & bella, 1994; bella et al., 1996; carveni et al., 1997). recenti studi (gironi, 2003) hanno evidenziato che, mentre la maggior parte dell’edificio etneo è solidale con le zone circostanti, e si solleva con un tasso di circa 15 mm/anno, il settore delimitato dalla faglia della pernicana a settentrione e dall’arco congiungente il cratere centrale con aci castello a meridione è interessato da un movimento di abbassamento. nel presente articolo viene studiata in dettaglio l’attività di alcune delle suddette faglie, attraverso la rielaborazione dei dati reperibili in letteratura, rilievi geologico-geomorfologici di dettaglio e campagne di misurazioni realizzate attraverso l’utilizzo di estensimetri nel periodo 1994 – 2004. in particolare, vengono ricostruiti i campi macrosismici di alcuni terremoti che hanno interessato l’area, confrontando i risultati con i già esistenti dati di letteratura; il trattamento dei dati permette di ricostruire il movimento medio delle singole faglie per il periodo compreso tra il 1805 e il 1989; la sommatoria dei movimenti lungo i piani di faglia viene messa in relazione con i fenomeni di variazione del livello del mare registrati nell’area costiera sottoposta geograficamente alle strutture tettoniche. dato il breve intervallo di tempo considerato, si ritiene che la maggior parte delle variazioni del livello marino riconosciute siano svincolate da fenomeni di eustatismo e collegate essenzialmente alla dinamica del basso versante orientale etneo. 2. inquadramento geologico-strutturale il monte etna, con la sua altitudine di poco superiore ai 3.300 metri e col diametro massimo di 44 chilometri, è il maggiore vulcano attivo del continente europeo; esso è uno strato-vulcano complesso, risultante dalla sovrapposizione di prodotti emessi da diversi edifici (gemmellaro, 1858; lyell, 1859) poggianti su un basamento in parte alloctono, formato da rocce di età compresa tra il cretaceo ed il pleistocene (cristofolini et al., 1979; romano et al., 1979; lentini, 1982). il bacino del mediterraneo centrale, nel quale si inserisce l’etna, è caratterizzato da differenti domini strutturali, la cui genesi è da inquadrare nel contesto collisionale tra la placca africana e la placca europea; le due masse continentali si scontrano e si saldano tra loro formando l’orogene appenninico – maghrebide, una catena corrugata che forma la dorsale appenninica e, attraversando l’arco calabro, la sicilia ed il canale di sicilia, prosegue lungo le coste nord-africane del maghreb. l’edificio vulcanico etneo sorge al limite tra diversi domini strutturali della sicilia orientale, dove la crosta oceanica ionica e la crosta continentale dell’avampaese ibleo si inflettono sotto il fronte dell’orogene appenninico maghrebide (finetti et al., 1996) (fig. 1). l’avampaese ibleo costituisce il margine della placca africana (burollet et al., 1978), zona stabile verso cui convergono le falde neogeniche dell’orogene appenninico maghrebide. esso è costituito da una potente successione prevalentemente carbonatica compresa tra il triassico ed il pleistocene medio; vi si intercalano, a vari livelli, prodotti effusivi basici cretacei, miocenici e plio-pleistocenici, la cui risalita è stata provocata da intense fasi tettoniche distensive (cristofolini, 1966; di grande, 1967; 1969; 1972; patacca et al., 1979; carbone et al., 1982 c; lentini et al., 1986; carbone et al., 1987; carveni et al., 1991 a; 1991 b; 1993; carveni & sturiale, 1999). esso confina ad oriente con la crosta oceanica del bacino ionico (finetti, 1982), tramite la scarpata ibleo-maltese, di origine tettonica (finetti & morelli, 1972), originata da un sistema di faglie normali a gradinata, il cui prolungamento verso settentrione interseca il fianco orientale dell’edificio etneo (lo giudice et al., 1982; carbone et al., 1982 a; 1982 b); la scarpata ibleomaltese si sarebbe formata in un’unica grande fase tortoniana, con riattivazioni di minore entità posteriormente al deposito degli infrapliocenici trubi; a luoghi sono state individuate importanti emissioni vulcaniche connesse alla scarpata (casero et al., 1984). lanzafame & bousquet (1997) ritengono che la scarpata ibleo-maltese sia solo un segmento di un importante sistema di faglie con direzioni comprese tra nnw-sse e nw-se, che, attraversando la sicilia nordorientale e il tirreno meridionale, raggiunge vulcano, lipari e salina. l’orogene appenninico-maghrebide si è formato in seguito all’accavallamento della catena kabilocalabride, costituita da falde di basamento cristallino interessate da metamorfismo ercinico con resti dell’originaria copertura sedimentaria meso-cenozoica, sulla catena appenninico-maghrebide, edificio orogenico formato dalla sovrapposizione di falde sud-vergenti, il cui corrugamento ha interessato, deformandole, le coperture sedimentarie della tetide e dei paleodomini minori ad essa associati, originariamente ubicati tra il margine della placca europea ed il margine della placca africana (finetti et al., 1996). fig. 1 schema strutturale della sicilia (da finetti et al., 1996). ai) avampaese ibleo; cam) catena appenninico-maghrebide; ckc) catena kabilo-calabride; cs) catena sicana; e) edificio vulcanico etneo; agc) avanfossa gela – catania; sim) scarpata ibleo-maltese; smf) sistema di faglie messina – fiumefreddo; il rettangolo indicato dalla freccia corrisponde alla zona in studio. structural scheme of sicily (after finetti et al., 1996). ai) hyblaean foreland; cam) apennine-maghrebian chain; ckc) kabilo-calabrian chain; cs) sicana chain; e) mount etna volcano; agc) gela – catania foredeep; sim) hyblaean-malta escarpment; smf) messina – fiumefreddo fault system; narrow indicates position of studied area. l’avanfossa gela-catania è un bacino subsidente formatosi in seguito alla flessione dell’avampaese ibleo sotto le coltri alloctone della catena appenninicomaghrebide; essa è stata colmata da sedimenti pliopleistocenici che coprono in parte la falda di gela, la quale rappresenta il fronte più avanzato della catena (lentini, 1982). ad iniziare dal pleistocene inferiore, in questo quadro geodinamico compressivo, intense fasi tettoniche hanno causato un’elevata distorsione lungo il margine settentrionale della placca africana, a causa della differente velocità con cui avviene la subduzione al di sotto della catena appenninico maghrebide (van bemmelen, 1969; morelli, 1970; selli & fabbri, 1971; giese & morelli, 1975), e ciò ha determinato uno stiramento crostale che ha dato luogo a fratture con direzione nwse, ne-sw ed e-w (ghisetti & vezzani, 1982; scandone, 1982); all’intersezione di tali strutture si è formata una zona di debolezza attraverso la quale avviene la risalita di magmi sub-crustali (frazzetta & villari, 1981). sulla genesi del vulcano e sul quadro strutturale sono reperibili in letteratura numerosi modelli: 1) intersezione tra due importanti lineamenti strutturali: la scarpata ibleo-maltese e il sistema di faglie messina fiumefreddo (ogniben et al., 1975; mcguire et al., 1997); 2) risultato di una tettonica estensionale che ha portato alla formazione di un graben in corrispondenza dell’attuale piana di catania (di geronimo et al., 1978); 3) processi di rifting tra il blocco maltese siciliano ed il bacino ionico (gillot et al., 1994; continisio et al., 1997); 4) deformazione al footwall di una faglia normale appartenente al sistema distensivo siculo-calabro ad andamento wnw-ese (monaco et al., 1997); 5) risalita di magmi dal mantello a causa di un hot spot (tanguy et all., 1997); 6) roll-back di una porzione di litosfera subdotta al di sotto del mar tirreno (gvirtzman & nur, 1999). a causa di un sollevamento regionale, l’attività eruttiva dell’etna, inizialmente sottomarina e fissurale, è diventata in seguito subaerea ed a carattere centrale; ciò ha causato una variazione nel meccanismo di risalita dei magmi, con conseguente cambiamento del chimismo: da lave subalcaline si è passati a prodotti più o meno differenziati della serie alcalino-sodica (romano, 1982). sulla base di datazioni radiometriche del rapporto k/ar, sono stati distinti quattro periodi di attività dell’etna, intervallati da periodi di quiescenza (gillot et al., 1994): il primo periodo (da 520.000 ± 40.000 a 270.000 anni fa) è caratterizzato da vulcanismo tholeiitico (fig. 2: 6), con fasi eruttive separate da lunghi periodi di quiescenza; il secondo periodo (da 168.000 ± 8.000 a 100.000 anni fa) è evidenziato da un radicale cambiamento del tipo di attività (strato-vulcani al posto di fessure eruttive) e del chimismo dei prodotti da subalcalini ad alcalini (fig. 2: 5); durante il terzo periodo (tra 80.000 e 60.000 anni fa) si formò un grande complesso vulcanico poligenico chiamato trifoglietto (fig. 2: 4); il quarto periodo (da 35.000 anni fa ad oggi) corrisponde allo sviluppo di un grande strato-vulcano, il mongibello; un’importante fase, caratterizzata da eruzioni pliniane e idromagmatiche, permette di suddividere questo periodo in due parti: mongibello antico (fig. 159sollevamenti a grande scala ... 2: 2) e mongibello recente (fig. 2: 1). tra l’attività del trifoglietto e quella del mongibello si inserisce un episodio di parziale smantellamento dell’edificio etneo, con il trasporto di ingenti masse detritiche che diedero luogo ad un deposito ghiaioso (fig. 2: 3), localmente conosciuto col nome di chiancone (romano & sturiale, 1981; romano, 1982; guest et al., 1984; kieffer & tanguy, 1993); contemporaneamente all’estinzione dei vecchi centri eruttivi si verificava uno spostamento del condotto principale verso nw (romano, 1982). 3. assetto strutturale del versante orientale etneo platania (1922), basandosi sui movimenti registrati lungo alcuni piani di faglia in occasione di forti terremoti (1865, 1879, 1881, 1911 e 1920), teorizza un’origine sismotettonica per alcune scarpate ubicate sul versante orientale dell’edificio vulcanico etneo; la conferma gli viene fornita da puglisi (in platania, 1922); questi, direttore della società acque di casalotto, in base a rilievi di superficie e dati provenienti da pozzi e gallerie drenanti, descrive quattro faglie con direzione circa ns, comprese tra la periferia occidentale di aci sant’antonio e l’alta falesia della timpa di acireale (fig. 3: sas); questo autore ipotizza che le faglie si siano formate come reazione di una parte dell’edificio etneo al graduale sollevamento della zona; in particolare egli rileva, lungo alcune gallerie drenanti, sia il rigetto verticale, sia lo spostamento orizzontale verso il mare, e su queste basi ipotizza l’esistenza di un fenomeno franoso che inizia nella zona di aci bonaccorsi e si propaga verso la costa; il fatto che egli descriva una “stratificazione inclinata verso monte” lungo i piani di fratturazione, suggerisce che si tratti di faglie listriche. carapezza (1962), nel tentativo di determinare una relazione tra la tettonica regionale e le zone di minore resistenza dell’etna, identifica un rift lungo il fianco orientale dell’edificio vulcanico. marchesini et al. (1964) riconoscono quattro principali allineamenti tettonici, con direzioni n-s, enewsw, ne-sw e nw-se. frazzetta & romano (1978) identificano due allineamenti alimentatori preferenziali per le aree ad alta probabilità di eruzioni: una nel settore circolare compreso tra ne-sw e ene-wsw, la seconda con direzione nnw-sse. lo giudice et al. (1982) riconoscono nell’area etnea e nelle zone circostanti varie direttrici di faglie: le più importanti hanno direzione n 60° e, n 30° e, n 15° w e n 60° w. kieffer (1983 a; 1983 b) ipotizza scivolamenti gravitativi di parte del versante orientale dell’edificio vulcanico, ed attribuisce il fenomeno alla ripetuta intrusione di magma attraverso un rift di ne e un rift meridionale. l’ipotesi di uno scivolamento gravitativo viene ripresa da azzaro et al. (1989 a) e da neri et al. (1991). borgia et al. (1992), sulla base dei risultati ottenuti da ferrari et al. (1991) sui dicchi affioranti nella valle del bove, ipotizzano uno spreading radiale del substrato dell’etna verso se. lo giudice & rasà (1992) ritengono invece che si tratti di movimenti puramente gravitativi, che provocano 160 fig. 2 schema lito-stratigrafico del versante orientale dell’edificio vulcanico etneo e ubicazione delle località con tracce morfologiche e/o geologiche di antichi livelli del mare. cc) cratere centrale; 1) vulcaniti del mongibello recente; 2) vulcaniti del mongibello antico; 3) ghiaie del chiancone; 4) vulcaniti dei centri eruttivi del trifoglietto; 5) vulcaniti dei centri eruttivi alcalini antichi; 6) lave sub-alcaline di base; 7) unità post-orogene; 8) unità calabridi ed antisicilidi; 9) unità sicilidi. litho-stratigraphical scheme of etna eastern flank and location of morphological and/or geological sea level changes evidences. cc) central crater; 1) recent mongibello volcanic rocks; 2) ancient mongibello volcanic rocks; 3) chiancone gravels; 4) trifoglietto eruptive centres volcanic rocks; 5) ancient alkaline eruptive centres volcanic rocks; 6) basement sub-alkaline lava flows; 7) post-orogenetic units; 8) calabridi and antisicilidi units; 9) sicilidi units. p. carveni et al. 161 fig. 3 ubicazione delle più importanti faglie del versante orientale dell'etna: fcm) faglia capo schisò – foce del torrente macchia; ff) faglia di fondachello; fg) faglia di giardini; fm) faglia di moscarello; fma) faglia di mascalucia; fmg) faglia milo – giarre; fmr) faglia macchia – riposto; fms) faglia macchia – stazzo; fn) faglia di naxos; fp) faglia della pernicana; fpvc) faglia praiola – villa calanna; frn) faglia della ripa della naca; frp) faglia della ripa di piscio; fsl) faglia di san leonardello; ft) faglia di trecastagni; ftm) faglia del torrente minissale; sp) sistema di piedimonte. centri abitati: a) acireale; ab) aci bonaccorsi; ac) acicatena; as) aci sant’antonio; fi) fiumefreddo; fo) fondachello; g) giardini; m) mascalucia; ma) mascali; s) stazzo; sa) sant’alfio; st) santa tecla; t) trecastagni. centri eruttivi: cc) cratere centrale; mi) monte ilice; rne) rift di ne. i triangoli indicano zone in cui sono stati misurati sollevamenti e abbassamenti fino a 15 mm/anno (da gironi, 2003; carveni et al., 2005). location of the main faults on eastern flank of mt. etna volcano: fcm) cape schisò – macchia stream mouth fault; ff) fondachello fault; fg) giardini fault; fm) moscarello fault; fma) mascalucia fault; fmg) milo – giarre fault; fmr) macchia – riposto fault; fms) macchia – stazzo fault; fn) naxos fault; fp) pernicana fault; fpvc) praiola – villa calanna fault; frn) ripa della naca fault; frp) ripa di piscio fault; fsl) san leonardello fault; ft) trecastagni fault; sp) piedimonte system. towns: a) acireale; ab) aci bonaccorsi; ac) acicatena; as) aci sant’antonio; fi) fiumefreddo; fo) fondachello; g) giardini; m) mascalucia; ma) mascali; s) stazzo; sa) sant’alfio; st) santa tecla; t) trecastagni. eruptive centres: cc) central crater; mi) monte ilice; rne) ne rift. triangles indicate uplift or lowering zones up to 15 mm/y (after gironi, 2003; carveni et al., 2005). sollevamenti a grande scala ... 162 lo scivolamento verso sse della porzione dell’edificio etneo delimitata a settentrione dalla faglia della pernicana e dal rift di ne, e a se dalle faglie di mascalucia e trecastagni (fig. 3). la documentazione storica relativa ai terremoti avvenuti sul basso versante orientale etneo negli ultimi due secoli e le conseguenze morfologiche dei movimenti tettonici sono analizzate in una serie di articoli (adorni & carveni 1993 a; 1993 b; carveni & bella, 1994; bella et al., 1996; carveni et al., 1996; 1997; gresta et al., 1997). dall’analisi dei sistemi di faglie che nel pleistocene sono stati attivi in sicilia orientale, sulla base di informazioni geologico-strutturali e morfologiche e dell’analisi di sezioni sismiche a mare, monaco & tortorici (1995) e monaco et al. (1995; 1997) distinguono un sistema acireale – sant’alfio (faglie normali con componente trascorrente destra nnw-sse) e un sistema di piedimonte (faglie normali e fratture d’estensione nne-ssw); entrambi i sistemi, associati ad un’estensione wnw-ese, formano scarpate di età suprapleistocenico-olocenica, le quali esercitano un controllo sulla topografia e sul reticolo idrografico. ricerche basate su rilievi effettuati da satelliti (gironi, 2003) evidenziano un sollevamento in atto di tutta la zona etnea con punte massime di 15 mm/anno, con eccezione del settore delimitato a settentrione dalla faglia della pernicana e sua prosecuzione verso oriente, e a sw dalle faglie di mascalucia e trecastagni: questa zona risulta essere interessata da un fenomeno di abbassamento con un tasso massimo di circa 15 mm/anno a stazzo, frazione di acireale, dove un molo costruito nel 1949 e alto circa 90 centimetri, attualmente si trova al livello del mare (figg. 3 e 4). 4. variazioni del livello marino: dati di letteratura già a partire dalla prima metà del xix secolo sono reperibili in letteratura dati inerenti a movimenti differenziali della linea di costa nel tratto di mare jonio compreso tra taormina a settentrione e catania a meridione (fig. 2); la lacuna di informazioni riguarda la correlazione tra i vari dati esistenti in letteratura. la loro correlazione evidenzia la presenza di un’area centrale localizzata nel sito di torre archirafi (fig. 2: g) soggetta a fenomeni di abbassamento, confinata a nord e a sud, lungo la linea di costa, da due aree in sollevamento. per quanto riguarda i fenomeni di sollevamento, dalle ricerche bibliografiche risulta che il primo a riconoscere tracce di variazioni del livello marino lungo la costa ionica della sicilia è stato gemmellaro (1837), il quale ha descritto il solco di battente esistente attorno ai promontori di capo sant’alessio e capo sant’andrea, nei pressi di taormina (fig. 2: a). gemmellaro (1859) determina un sollevamento della costa compresa tra catania e aci trezza, in base al ritrovamento di depositi di origine marina tra 0,4 e 1 metro sul livello marino nella baia di ògnina (fig. 2: b), di una sabbia conchiglifera a 1 metro di quota sul lato settentrionale della rupe di aci castello (fig. 2: c) e di incrostazioni conchigliari comprese tra 4 e 13 metri di quota sull’isola lachea (fig. 2: d). platania (1905 a) osserva che le argille pleistoceniche affioranti a 700 metri di quota presso santa maria la vena (fig. 2: e) costituiscono l’indizio di un recente sollevamento del versante orientale dell’etna; inoltre, in base all’esistenza di incrostazioni di conchiglie a 5,4 metri di quota sulla falesia di aci castello (fig. 2: f), formata da una colata di lava datata al 1169 da sartorius von waltershausen (1880), calcola un sollevamento della zona costiera di 8 millimetri all’anno; è chiaro comunque che il calcolo è errato per difetto: le incrostazioni di conchiglie allora osservate a 5,4 metri d’altezza non si saranno formate sulla superficie della colata appena raffreddata, ma su una superficie d’erosione, diversi anni dopo la fine dell’eruzione: ne deriva una maggiore velocità di sollevamento. platania (1905 b; 1912; 1915) descrive una serie di marmitte dei giganti presenti sull’isola lachea (fig. 2: d) e nel porto di aci trezza (fig. 2: h); attribuendone la genesi ad onde di tempesta, non si rende conto della prova di un abbassamento relativo del livello del mare che tali morfologie testimoniano. platania (1922) riconosce il recente sollevamento generale della regione etnea, comprovato dalle argille quaternarie affioranti a presa (fig. 2: i), santa maria la vena (fig. 2: e) e santa venera (fig. 2: l); egli inoltre segnala l’esistenza di incrostazioni calcaree, contenenti frammenti di stoviglie di epoca romana, ubicate intorno a 14 metri sul livello del mare lungo la costa di aci castello (fig. 2: m); tracce di erosione marina riconosce egli stesso intorno a 80 metri di quota sulla timpa di santa maria la scala (fig. 2: n). de fiore (in zambonini, 1925) descrive le argille con faune calabriane affioranti sulla collina di vampulieri, presso aci trezza, a 120 metri di quota (fig. 2: o). secondo romano & sturiale (1981) la colata lavica che circonda ad occidente la rupe di aci castello, e che presenta tracce di abrasione marina e fori di litodomi a 6 metri di quota, è stata emessa tra il 122 a.c. e il 252-253 d.c., testimoniando un sollevamento della zona costiera di circa 3 mm/anno. per quanto riguarda i fenomeni di abbassamento l’unica testimonianza ci viene tramandata da platania (1905 a) il quale rileva tale fenomeno lungo la costa in corrispondenza dell’abitato di torre archirafi (fig. 2: g), dove i ruderi dell’eponima torre, eretta nel 1594 (scarlata, 1993), si trovavano, al momento in cui egli fece le fig. 4 il molo nuovo e il molo vecchio di stazzo. new and old docks in stazzo port. p. carveni et al. indagini, a due metri di profondità; se il disegno attribuito da scarlata (1993) a camillo camiliani è fedele, la torre in oggetto sorgeva su una falesia alta circa 4 metri: se ne deduce un abbassamento della costa di circa 6 metri nell’arco di poco più di 300 anni, con un tasso medio calcolato di 2 centimetri all’anno. 5. variazioni del livello marino: nuovi dati sulla scorta di rilievi, e sulla base di una rilettura critica della letteratura, sono state riconosciute altre testimonianze geomorfologiche di variazioni del livello marino. 5.1. la rupe di aci castello nella zona di aci castello affiorano alcuni dei prodotti vulcanici più antichi emessi nella zona etnea (gillot et al., 1994); nel complesso, la rupe su cui sorge il castello è formata in prevalenza da lave a cuscini e brecce vulcanoclastiche (corsaro & cristofolini, 2000) facenti parte delle lave sub-alcaline di base (romano et al., 1979); a sw della rupe (fig. 5) si trova una colata lavica subaerea, emessa tra il 122 a.c. e il 252-253 d.c. (romano & sturiale, 1981), poggiante su una piattaforma d’abrasione marina ubicata a circa 4,5 metri di altezza, costituita da lave a cuscini, con chiare tracce di metamorfismo da contatto (fig. 6). tutt’intorno alla rupe esiste un’altra piattaforma d’abrasione marina impostata su lave a cuscini, ubicata a un metro circa di quota (fig. 5); nella zona orientale della rupe si vedono 3 nicchie assimilabili a solchi di battente, rispettivamente alle quote 1,5, 6 e 8,7 metri circa. l’insieme delle testimonianze morfologiche consente la seguente ricostruzione: 1) il moto ondoso scava il solco di battente attualmente ubicato a 8,7 metri di quota (fig. 7 a: a); 2) in seguito ad un sollevamento della zona si forma il solco di battente di quota 6 metri (fig. 7 b: b); 3) un secondo sollevamento è testimoniato dalla piattaforma di quota 4,5 metri (fig. 7 b: c); 4) in occasione di un terzo sollevamento la rupe, precedentemente isolata, si unisce alla terraferma; la piattaforma d’abrasione di cui al punto precedente emerge e questa, tra il 122 a.c. e il 252-253 d.c., viene ricoperta da una colata di lava (fig. 7 c); 5) in seguito ad un innalzamento relativo del livello del mare, la colata lavica viene interessata dall’erosione marina che vi forma una falesia, presto colonizzata da litodomi (fig. 7 d); 6) un nuovo abbassamento relativo del livello marino porta alla formazione del solco di battente di quota 1,5 metri e della piattaforma di quota 1 metro (fig. 7 e); 7) un ulteriore sollevamento della zona porta alla configurazione attuale (fig. 7 f). 5.2. il porto di stazzo stazzo, frazione del comune di acireale, è stata costruita lungo la costa (fig. 3), all’estremità di una colata lavica del 1329 emessa da una fessura eruttiva ubicata al margine sud-orientale dell’edificio piroclastico di monte ilice (romano & sturiale, 1982); l’erosione marina ha prodotto una falesia con numerose piccole insenature. al limite meridionale della colata, al contatto con le preesistenti vulcaniti, attribuite all’attività del mongibello recente (romano et al., 1979), esiste una piccola rada, utilizzata come riparo per barche da pesca, con un molo di recente costruzione; accanto a questo se ne trova uno più antico, inutilizzabile in quanto il suo pavimento si trova a fior d’acqua (fig. 4); da informazioni assunte in loco, risulta che il molo vecchio è stato costruito nel 1949, e che esso era alto circa 1 metro sul livello del mare; ciò consente di calcolare un abbassamento della zona costiera di circa 1,8 cm/anno per il periodo considerato. 6. analisi della sismicità storica dell’area al fine di trovare le cause che spieghino il fenomeno di abbassamento registrato a torre archirafi e a stazzo, in contrasto con il generale sollevamento dell’intera area etnea, si sono studiate le più importanti faglie presenti sul basso versante orientale dell’etna e la relativa sismicità; la zona è interessata sia da un’attività sismica “lontana”, dovuta a risentimenti di importanti eventi con epicentri ubicati lungo l’arco calabropeloritano o nel plateau ibleo, sia da una frequente sismicità locale con profondità ipocentrali comprese tra 0,5 e 2 chilometri (patanè, 1975; benina et al., 1984; lo 163 fig. 6 il contatto tra la colata sub-aerea emessa tra il 122 a.c. e il 252-253 d.c. e quella sub-marina sottostante. stratigraphic boundary between subaerial lava flow (122 b.c. – 252-253 a.d.) and underlying submarine lava. fig. 5 panoramica della rupe di aci castello. panoramic view on aci castello castle rock. sollevamenti a grande scala ... 164 fig. 7 ipotizzata evoluzione morfologica della falesia a meridione della rupe di aci castello. hypothetic morphological evolution of southern cliff of aci castello castle rock. p. carveni et al. giudice, 1985; bottari et al., 1989; azzaro et al., 1989 a; 1989 b; lo giudice & rasà, 1992; carveni et al., 1996; gresta et al., 1997), con modesto raggio di avvertibilità e campo macrosismico di pochi chilometri quadrati. nella zona è stata inoltre individuata l’esistenza di lenti scorrimenti asismici (creep asismici) lungo alcuni piani di faglia (lo giudice, 1985). le faglie presentano meccanismi distensivi; è stato evidenziato che gli epicentri dei sismi sono localizzati prevalentemente lungo i segmenti settentrionali delle relative faglie, mentre lungo i tratti meridionali delle stesse si registrano solo fenomeni di creep asismico (carveni & bella, 1994). l’integrazione tra dati provenienti da indagini geoelettriche (cassinis et al., 1970) e dati relativi alle profondità ipocentrali di alcuni sismi (patanè, 1975; postpischl, 1985; azzaro et al., 1989 a; 1989 b; bottari et al., 1989) ha fatto ipotizzare una genesi di tipo gravitativo profondo per i movimenti sismici in oggetto (carveni & bella, 1994). per quanto di magnitudo relativamente modesta, alcuni dei terremoti avvenuti in quest'area hanno provocato ingenti danni alle costruzioni e la perdita di numerose vite umane; fra gli effetti cosismici sono stati segnalati spostamenti reciproci dei blocchi lungo i piani di faglia e l'apertura di fessure nel terreno (grassi, 1865; silvestri, 1865; 1866; 1867; 1883; platania & platania, 1894; platania, 1908; 1920; riccò, 1911; 1912; sabatini, 1914; castorina, 1920; cumin, 1954; riuscetti & distefano, 1971; azzaro et al., 1989 a). in occasione del sisma del 29 gennaio 1989 è stato registrato un movimento transtensivo destro (azzaro et al., 1989 a); altri autori hanno descritto slickenside sui piani delle faglie della timpa di moscarello e della timpa di santa tecla (bousquet et al., 1987). i dati relativi ai sismi con intensità maggiore al vii grado della scala ems-98 sono riportati in tabella 1. 6.1. attività della faglia di moscarello la faglia di moscarello è una faglia diretta con direzione complessiva n 20° w, geologicamente e sismicamente attiva (sensu bosi & carraro, 1979), sviluppo lineare di 10 chilometri circa, blocco orientale ribassato con piano quasi verticale; i suoi movimenti hanno provocato una scarpata che raggiunge lungo il tratto settentrionale un dislivello di 200 metri (timpa di moscarello). ferreri et al. (2000), tramite trincee esplorative, hanno riconosciuto i risultati di una fagliazione a scatti, con abbassamenti relativi compresi tra 2 e 4 mm/anno. 6.1.1. sisma del 19 luglio 1865 tra tutti i terremoti verificatisi sul fianco orientale dell'etna di cui si hanno notizie, quello avvenuto il 19 luglio 1865 è stato certamente il più forte. il villaggio di fondo macchia, costituito da almeno 90 edifici tra case e magazzini, distribuiti in un'ampia area, fu letteralmente raso al suolo: caddero a terra, verso ponente, tutte i manufatti, compresi i muri a secco alti meno di un metro (silvestri, 1865). lungo il piano di faglia fu osservato un abbassamento del blocco orientale variabile, a luoghi, da un minimo di 30 a un massimo di 60 centimetri; si formarono crepe parallele alla frattura principale con espulsione dal terreno di blocchi lavici e radici di alberi; il sisma provocò anche la caduta di massi lungo la timpa di moscarello (silvestri, 1865; grassi, 1865). nella figura 8 è rappresentato il campo macrosismico. 6.2. attività della faglia di san leonardello la faglia di san leonardello è una faglia diretta, geologicamente e sismicamente attiva, parallela alla faglia di moscarello (n 20° w), con sviluppo lineare di 5,5 chilometri e blocco orientale ribassato; essa si estende da macchia fino alla costa compresa tra 165 tab. 1. * cpti = catalogo parametrico dei terremoti italiani; 1) grassi, 1865; 2) riccò, 1911, 1912; 3) silvestri, 1865; 4) riuscetti & distefano, 1971; 5) patanè, 1975; 6) castorina, 1920; 7) platania, 1920; 8) cumin, 1954; 9) postpischl, 1985; 10) azzaro et al., 1989; 11) baratta, 1900. data epicentro faglia i0 (ems-98) mm d (km) rv (m) t rif 11 luglio 1805 fondo macchia moscarello viii-ix (?) 1, 2 26 gennaio 1855 fondo macchia moscarello viii 4.24 (*) dx 1 19 luglio 1865 fondo macchia moscarello xi 4.94 (*) 1.6±16% (9) 0,6 dx 1, 3 12 febbraio 1881 san matteo macchia – stazzo viii 3.8 8, 11 15 ottobre 1911 fondo macchia moscarello x 1.0 0,9 dx 2 26 settembre 1920 codavolpe san leonardello x 4.42 (*) 0.5±3.4% (9) 0,6 6, 7 8 aprile 1950 codavolpe san leonardello ix 4.0 0.7±13.6% (9) 8, 9 21 aprile 1971 sciara moscarello x 3.90 (*) 4 19 agosto 1973 mangano moscarello vii 5 29 gennaio 1989 codavolpe san leonardello viii 0.5±7.7% (9) 0,3 dx 10 sollevamenti a grande scala ... stazzo e santa tecla, ed è evidenziata da tratti di scarpate rettilinee con dislivelli massimi di 30 metri. mentre lungo il settore settentrionale della faglia si sono verificati sismi di una certa intensità, il tratto meridionale è interessato da movimenti lenti (creep asismici); sono stati da noi misurati spostamenti di 1,2 cm/anno lungo alcune crepe in edifici di san leonardello. 6.2.1. sisma del 26 settembre 1920 gli effetti del terremoto del 26 settembre 1920 sono stati descritti da castorina (1920) e da platania (1920); il relativo campo macrosismico e rappresentato nella figura 9. a codavolpe crollarono molte case e tutte le altre furono danneggiate; si formarono nel terreno numerose fessure con direzione nnw-sse e fu notato lo spostamento di pesanti mobili verso nw, come reazione inerziale al movimento di trascorrenza destro. a san leonardello rimasero lesionate parecchie case (castorina, 1920). lungo la scarpata della faglia furono misurati rigetti verticali compresi tra un minimo di 30 e un massimo di 60 centimetri; la frattura beante poteva essere seguita sul terreno per diversi tratti, ognuno lungo centinaia di metri; furono segnalate fessure parallele alla faglia, a volte riunite in coppie; presso l'abitato di san leonardello si riaprì una frattura già formatasi in occasione del sisma del 1865 (castorina, 1920). 6.3. attività della faglia macchia-stazzo la faglia macchia stazzo è una faglia antitetica rispetto alle due precedenti: con direzione n 20° w, sviluppo lineare di poco più di 8 chilometri e blocco occidentale ribassato, essa delimita ad oriente il graben di san leonardello. gli indizi morfologici che ne fanno riconoscere l'esistenza sono meno evidenti di quelli relativi alle due faglie già descritte, a causa di una minore attività sismica: essa è eviden166 fig. 8 campo macrosismico del terremoto di fondo macchia del 19 luglio 1865. fondo macchia 1865, 19th july earthquake macroseismic field. fig. 9 campo macrosismico del terremoto di codavolpe del 26 settembre 1920. codavolpe 1920, 26th september earthquake macroseismic field. p. carveni et al. ziata da una scarpata quasi rettilinea, più evidente lungo il tratto meridionale dove ha causato diversi fenomeni di cattura di piccoli corsi d'acqua (adorni & carveni, 1993 a; 1993 b) carveni & bella, 1994; bella et al., 1996; carveni et al., 1997). l'unico sisma collegato a questa faglia di cui si abbiano notizie è avvenuto il 12 febbraio 1881; fratture e dislocazioni in manufatti costruiti in epoca posteriore al sisma evidenziano l'esistenza di fenomeni di scorrimento asismico tra i blocchi (creep asismici). da baratta (1900) si evince che i maggiori danni provocati dal sisma del 12 febbraio 1881 non sono stati subiti dal villaggio di codavolpe, fino ad oggi considerato epicentro relativo a questo sisma, ma dalla frazione di san matteo, dove si verificarono crolli totali di piccole case rustiche; tutto ciò porta a riconoscere la faglia macchia stazzo come responsabile di tale sisma, e non, come finora si era creduto, la faglia di san leonardello; ciò è confermato da quanto riportato da cumin (1954), secondo il quale in occasione di questo terremoto si sarebbe formata una frattura proprio alla base della scarpata della faglia macchia stazzo. il relativo campo macrosismico è stato ricostruito nella figura 10. a questo sisma è stata attribuita un'intensità epicentrale dell'viii grado, con mm 3,8 (postpischl, 1985), e del vi-vii grado (gresta et al., 1997). 7. discussione dei dati e conclusioni lo studio morfo-tettonico qui presentato, integrato con i risultati ottenuti da numerosi autori precedenti, permette di dare una spiegazione del fenomeno di abbassamento riscontrabile sul versante orientale etneo, e in particolare lungo il tratto di costa compreso tra la spiaggia di torre archirafi a settentrione e stazzo a meridione. le testimonianze geologico-geomorfologiche di un sollevamento generalizzato del territorio etneo sono note: basti citare gli affioramenti di argille marnose azzurre infrapleistoceniche di santa venera, presa e vena già individuati da platania (1905 a) e i numerosi terrazzi fluviali lungo le valli dei fiumi simeto e alcantara (romano et al., 1979); inoltre, nel già citato articolo di gironi (2003) risulta che il sollevamento dell’edificio etneo è solidale con le circostanti zone; fa eccezione il settore grossolanamente triangolare col vertice in corrispondenza del cratere centrale e la base lungo la costa ionica, delimitato a settentrione dalla faglia della pernicana, a nw dal rift di ne, a occidente e sw da una fascia di fratture eruttive e faglie dirette che, partendo dai crateri sommitali, scendono lungo il fianco meridionale dell’edificio vulcanico e giungono alla costa ionica tra la baia di ògnina e aci castello. il territorio compreso all’interno di questo settore è interessato dall’attività di alcune faglie dirette, appartenenti al sistema con direzione nnw-sse che ha dato luogo alla scarpata ibleo-maltese; esse, formando tra l’altro il graben di san leonardello, sono responsabili della sismicità locale e hanno giocato un ruolo fondamentale nel condizionare l’idrografia superficiale e l’andamento della linea di costa (adorni & carveni, 1993 a; 1993 b; carveni & bella, 1994; bella et al., 1996; carveni et al., 1997). dalla testimonianza di puglisi (in platania, 1922) risulta inoltre l’esistenza di un movimento traslativo verso oriente lungo i piani delle faglie con direzione n-s che interessano la zona di aci sant’antonio (fig. 3: sas). questo versante presenta un particolare assetto geologico-strutturale, in quanto vi affiorano prevalentemente lave, con subordinati prodotti piroclastici e depositi alluvionali, poggianti su un substrato di argille marnose azzurre infrapleistoceniche. in alcune zone il passaggio dalle argille del basamento preetneo alle soprastanti vulcaniti è stato determinato da cassinis et al. (1970); essi evidenziano l’esistenza di un orizzonte conduttivo assimilato alle argille marnose azzurre infrapleistoceniche a profondità variabile al di 167 fig. 10 campo macrosismico del terremoto di san matteo del 12 febbraio 1881. san matteo 1881, 12th february earthquake macroseismic field. sollevamenti a grande scala ... sotto della superficie di campagna. dal confronto di questi dati con i risultati di alcuni studi sulla sismicità locale, risulta che le profondità ipocentrali dei terremoti avvenuti a codavolpe il 26 settembre 1920 (km 0,5 ± 3,4%, postpischl, 1985) e il 29 gennaio 1989 (km 0,5 ± 7,7%, azzaro et al., 1989 a) corrispondono al passaggio dalle argille infrapleistoceniche alle soprastanti lave; analogamente, per il sisma di san giovanni bosco del 2 febbraio 1986, azzaro et al. (1989 b) hanno calcolato una profondità ipocentrale poco inferiore a 1 chilometro, e cassinis et al. (1970) individuano in questa zona il passaggio argille/vulcaniti a 950 metri o poco più. sulla base di questi dati è stata ipotizzata l’origine gravitativa profonda per i movimenti della faglia di san leonardello (carveni & bella, 1994; carveni et al., 1997); il particolare assetto geologico-strutturale del versante, il diverso comportamento meccanico dei due complessi litologici e le notevoli precipitazioni meteoriche, che raggiungono 1.300 mm/anno a zafferana (ferrara, 1975), possono essere considerati cause concomitanti all’instaurarsi di condizioni di instabilità. l’andamento delle curve isosisme dei terremoti attribuiti alla faglia di moscarello evidenzia un forte tasso di assorbimento dell’energia sismica in direzione nord: ciò aveva fatto ipotizzare l’esistenza di una faglia con direzione circa e-w in corrispondenza della valle del torrente macchia (carveni & bella, 1994; carveni et al., 1997). questa faglia, sinora non riconosciuta in letteratura, può corrispondere ad un lineamento morfologico con andamento wnw–ese (faglia milo – giarre, fmg in figura 3), identificato tramite l’analisi del modello digitale del terreno (dem, favalli et al., 1999). dall’esame del catalogo dei terremoti dell’etna (azzaro et al., 2000) si rileva che all’attività di questa presunta faglia possono essere attribuiti cinque sismi verificatisi tra il 7 ed il 28 marzo 1910. una serie di 71 piccoli terremoti, distribuiti tra il 1874 e il 1920 (azzaro et al., 2000), con epicentri localizzati lungo un segmento compreso tra il porto di riposto e macchia di giarre, evidenzia l’esistenza di un’altra faglia, anch’essa non descritta in letteratura; questa ipotizzata struttura tettonica è anche evidenziata da una colata ad andamento rettilineo (romano et al., 1979), riversatasi lungo una valle impostatasi, presumibilmente, in corrispondenza del piano di faglia (fig. 3: fmr). in conclusione risulta evidente che la sommatoria dei movimenti di abbassamento lungo i due lati del settore in studio e lungo il sistema delle faglie che formano il graben di san leonardello può essere considerato come un cedimento gravitativo profondo, reazione al movimento generale di sollevamento della regione, che si manifesta, principalmente, nel rigetto verticale delle faglie che formano il graben di san leonardello. i rigetti misurati in occasione di alcuni tra i più forti terremoti generati dalle faglie in esame (tabella 1), permettono di valutare, con buona approssimazione, un rigetto medio pari a 50 centimetri, e considerando un periodo di 200 anni, dal 1805 ad oggi, si è calcolato un tasso di abbassamento di circa 2,5 cm/anno per la zona di stazzo (2 cm/anno nel più breve periodo 1949-2005) e di 2 cm/anno per la zona di torre archirafi. studio effettuato con i fondi del m.i.u.r., nell’ambito delle ricerche “morfodinamica di zone vulcaniche e/o sismicamente attive” e “morfodinamica di zone costiere sismicamente attive”, responsabile pietro carveni. ringraziamenti ringraziamo gli anonimi referees per gli utili e costruttivi consigli. lavori citati adorni g. & carveni p. 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(1925) sopra un rapporto del prof. o. de fiore intorno ad un sollevamento delle coste orientali dell’etna. rend. r. acc. sc. fis. e mat., ser. iii, 31, 5 pp. 171 ms. ricevuto il 17 maggio 2005 testo definitivo ricevuto il 21 ottobre 2005 ms. received: may 17, 2005 final text received: october 21, 2005 sollevamenti a grande scala ... imp.pralong&reynard a proposal for a classification of geomorphological sites depending on their tourist value jean-pierre pralong & emmanuel reynard institute of geography university of lausanne, bfsh 2 dorigny ch-1015 lausanne switzerland jean-pierre.pralong@unil.ch, fax +41 (0) 21 692 30 75 abstract: j.p. pralong & e. reynard, a proposal for a classification of geomorphological sites depending on their tourist value. (it issn 0394-3356, 2005). this paper presents theoretical frameworks concerning the relationships between geomorphological landforms and processes and tourist and recreational activities. firstly, a global model connecting different components of these relationships is proposed. secondly, a particular model analysing how geomorphological landforms and processes are recognised and assessed as geomorphological sites in a context of tourist optimization and exploitation is developed. finally, an ensuing classification of geomorphological sites according to the use of their scenic, scientific, cultural and economic values is developed and illustrated by two case studies in the area of chamonix-mont-blanc (haute-savoie, france). riassunto: j.p. pralong & e. reynard, proposta per la classificazione di siti geomorfologici basata sul loro valore turistico. (it issn 0394-3356, 2005). l’articolo presenta tre quadri teoretici concernenti le relazioni tra forme e processi geomorfologici da una parte e attività ricreative e turistiche dall’altra parte. viene proposto prima un modello globale che mette in evidenza le differenti componenti di tali relazioni. e’ poi sviluppato un modello che analizza come vengono riconosciuti e valutati i siti geomorfologici in un contesto di valorizzazione e di sviluppo turistico. infine, viene sviluppata una classificazione dei siti geomorfologici secondo il loro valore scenico, scientifico, culturale ed economico, che viene poi illustrata con due esempi nella zona di chamonix-mont-blanc (alta savoia, francia). keywords: geomorphological sites, landscape, tourist offer, environmental impacts, natural risks, chamonix-mont-blanc. parole chiave: siti geomorfologici, paesaggio, offerta turistica, impatti ambientali, rischi naturali, chamonix-mont-blanc. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 315-321 1. introduction the relationships between geomorphology and tourism may be analysed in four ways (reynard et al., 2003) at the interface of the natural and socio-economic systems: 1. first of all, geomorphology may be a tourist resource as part of the primary or original offer, that means as an element of the landscape or as a support for particular activities (e.g. climbing, canyonning, etc.). in this sense, geomorphology is a potential for tourist development, a part of the attraction of a tourist site; 2. geomorphology may also be part of the secondary or derived offer, when tourist infrastructures (e.g. museums, didactic paths), instruments (e.g. pedagogic booklets) or services (e.g. guided visits) are proposed for optimizing the original offer; 3. geomorphological processes may create changes on the tourist and recreational activities and infrastructures (processes, hazards and risks); 4. tourist activities and development may also create impacts on geomorphological processes and forms (e.g. soil erosion, slope instability or landform destruction). the aim of this article is mainly to consider the first three points and also to propose a theoretical reflection about the relationships between geomorphological landforms and processes and tourist and recreational activities. thus, three frameworks will be developed: the first one as a global model at the interface of the natural and socio-economic systems, the second one as a model of optimization and exploitation in a tourist context, the third one as a classification allowing to distinguish various types of geomorphological sites. as application examples, two case studies, related to the mer de glace and bossons glaciers, in the area of chamonix-mont-blanc (haute-savoie, france), will be presented. 2. studied area the chamonix-mont-blanc region (fig. 1) is situated in the arve valley (haute-savoie, france). the studied area concerns the river floor (chamonix area) and the right (massif des aiguilles rouges) and the left sides (massif du mont-blanc) of the valley. chamonix is a small town of 10.109 permanent inhabitants (census 1999) and is one of the largest ski resorts in france with 4.630.000 nights in 1999 (debarbieux, 2000). the major economic income of the region comes from tourism (skiing, golf, hiking). winter tourism is largely predominant, but new forms of summer tourism (trekking, biking) are developing, especially on the right side, beside various natural reserves (aiguilles rouges, carlaveyron). from a geological point of view, the area is situated in the helvetic domain, composed principally by gneiss and granites from the aiguilles rouges and the mont-blanc units (espace mont-blanc, 2001). these two units are separated by the chamonix area situated 316 j.p. pralong & e. reynard in the valley floor and composed principally by limestones, marls and sandstones. morphologically, the valley floor is covered by glacial and alluvial deposits (dorthemonachon, 1986) and the right side presents a lot of famous glaciers (tour, argentière, mer de glace, bossons, bionnassay) whereas the left side is practically deprived of ice and presents a lot of lakes and wetlands. 3. conceptual frameworks 3.1. general framework the figure 2 presents the relationships existing between geomorphology and tourism. tourist use of geomorphological landforms is made through the exploitation of geomorphological sites (1). geomorphological sites (or geomorphological assets) are defined by panizza & piacente (1993; 2003) and quaranta (1993) as geomorphological landforms (and processes) that have acquired a scenic, scientific, cultural/historical and/or social/economic value due to human perception or exploitation. in our case, they can be considered as geomorphological landforms and processes (e.g. geysers, active volcanoes, glaciers) that have acquired a certain tourist value and that are optimized and exploited for tourist purposes. in that sense, geomorphological sites may be considered as part of the original (or primary) tourist offer (2), which can be defined as the whole of natural, social, cultural or historical features that produce the attraction of a site (barras, 1987). according to debarbieux (1995), the primary offer depends on the localisation of the landforms and tourists have to go in situ in order to obtain satisfaction. in the case of geomorphology, the original offer can be completely based on the presence of a geomorphological landform or process. the tourist attraction of the small village of la-chaux-les-passavants in the french jura is for example only due to the presence of an ice cave. on the other hand, geomorphology may represent only one part of the tourist value of a site or a region. to take an example, the sugar loaf is not fig. 1 map of the studied region. chamonix-mont-blanc (haute-savoie, france). carta della regione studiata. chamonix-mont-blanc (alta savoia, francia). fig. 2 relationships between geomorphology and tourism: conceptual framework (adapted from panizza, 2003 and reynard et al., 2003). relazioni tra geomorfologia e turismo: quadro concettuale (adattato da panizza, 2003 e reynard et al., 2003). the only reason for tourists to visit rio de janeiro. however, geomorphology is not only limited to the original offer. a site may become a tourist destination only if amenities (infrastructures, services) are proposed to the visitors (barras, 1987), in order to facilitate their staying and access. thus, the secondary offer depends on the localisation of the population and tourists have to go ex situ in order to gain satisfaction (debarbieux, 1995). that is the derived (or secondary) tourist offer that may be unspecialised (e.g. parking, tourist office, hostels, roads and railways, etc.) or specialised (e.g. guided visits of a cave, presence of ski lifts in a winter resort, etc.). exploitation of geomorphology for tourism needs a specialised secondary offer (3), that means services (e.g. the presence of specialised guides), instruments (e.g. didactic boards, booklets, etc.) or infrastructures (e.g. transportation facilities for accessing specific geomorphological points, museum), that allow the exploitation (4) of the geomorphological sites. thus, these two types of offer create goods and services for material uses (hiking, climbing) and immaterial uses (relaxation, contemplation). relationships between geomorphology and tourism are not limited to the exploitation of a site, based on the original and derived offer. it is also a question of changes, risks and impacts. on the one hand, geomorphological processes may create changes on tourism (5), especially geomorphological hazards as landslides, avalanches, floods, rockfalls, etc., which create a relationship of risks (6). landslides or floods may for example destroy tourist villages. in this sense, tourist offer is in a situation of vulnerability (7). on the other hand, tourist activities create impacts on geomorphological processes and landforms (8) (panizza, 2003). impacts may be negative or positive and direct, induced or indirect (cavallin et al., 1994). 3.2. optimization, exploitation and transformation of geomorphological sites more precisely, in order to understand how the relationships between geomorphology and tourism act in the case of tourist development, a second conceptual framework is proposed in figure 3. according to this model, three steps are considered: optimization, exploitation and transformation. 317a proposal for a classification ... the onset is the existence of landforms and processes, expression of the earth’s history (1), as well as geological items. by human perception, geomorphology is considered (or not considered) as interesting for tourist purposes. thus, landscapes with a certain scenic, scientific, cultural/historical and/or social/economic value are optimized (2) as (tourist) geomorphological sites. the optimization depends of the degree of ecological (or geomorphological) sensibility of the tourist actors. when clear ecological ideas are expressed, optimization of geomorphological sites may happen. as a result of an ecological stimulation, tourist developers have two possibilities of action: protection (3) and/or exploitation (4). protection may happen when geomorphological sites are particularly vulnerable to human presence (e.g. some wetlands). geomorphological sites may also be exploited by the tourist industry1 and in that sense, they become the basis for tourist project conception and implementation (e.g. tourist caves, natural parks, didactic paths, etc.) by social stimulation. the project implementation creates a derived offer and the sustainability of the project depends of the type of management (5), following the use of geomorphological site values (see fig. 4). when the project is fulfilled, it may transform (6) the geomorphology and create direct or indirect impacts and induced hazards, that modify (in a positive or a negative way) the original processes and landforms, as a result of the economic stimulation. examples of transformations are the destruction of speleothems by the opening of caves to tourist visits (direct impact), the decreasing of the intensity of processes responsible for bad-lands formation in the case of the creation of protected areas and parallel reduction of livestock activity (indirect impact), and the increase of erosion (and successive landslides and debris flow hazards) due to the creation of ski tracks in mountain areas (induced hazards). these anthropic modifications are recorded as earth history memory and cultural witnesses (1). geomorphological landforms and processes of a second generation are therefore created and also new geomorphological sites in the sense of “tourist landscape evolution”. we assume that sustainable tourist use of geomorphological sites is reached when they produce sufficient financial incomes without negative environmental impacts and in base of a global consensus between the various actors (tourist actors, visitors, land owners, ngos, etc.). 1 note that protection and exploitation are not exclusive and may happen simultaneously: that is for example the case in natural and national parks. some areas or objects are strictly protected and sometimes human access is prohibited (e.g. the central part of a national park), whereas other parts are open for tourist visits. fig. 3 conceptual model describing the optimization, exploitation and transformation of geomorphology in a context of tourist development. modello concettuale che descrive la valorizzazione, l’uso e la trasformazione della geomorfologia in un contesto di sviluppo turistico. 318 4. classification of geomorphological sites the comprehension of the relationships evidenced in figure 2 and 3 allows the classification of geomorphological sites related to their optimization, exploitation and transformation due to tourist and recreational activities. a typology is therefore presented on figure 4. three categories are proposed: geomorphological sites (in the strict and the broader sense) and geomorphological mediums. according to panizza & piacente (1993), geomorphological sites are created by the contact between geomorphology and society, more precisely by the human perception of the value of geomorphological processes and landforms (a). with this process of optimization, they acquire a certain scenic, scientific, cultural/historical and/or social/economic value due to geological, geomorphological, historical and social factors. three groups of geomorphological sites are possible to be defined according to their value (b): 1. if the scenic, scientific or cultural value is concerned at least, without taking into account the economic value, geomorphological assets are defined as geomorphological sites in the strict sense. these items can be exploited or not (c). in this case, exploitation should be understood in terms of protection (total, with no possibility of human use), which means without any tourist activities in the surrounding of the landforms. therefore, if a geomorphological site (in the strict sense), according to its value, is protected, it becomes a protected geomorphological site. otherwise, it stays a geomorphological site in the strict sense. 2. if the scenic, scientific, cultural or economic value is considered, geomorphological assets are defined as geomorphological sites in the broader sense. in this case, landforms may have a tourist function if they are exploited (c) and sometimes protected (partially, with possibility of human use). thus, geomorphological sites (in the broader sense) are considered as a tourist and cultural resource (with extensive or intensive use). in this case, the question of sustainable management of geomorphology is essential; a toointensive use of geomorphology may dramatically change the value(s) of the resource and therefore its classification. 3. finally, if only the economic value is taken into account, geomorphological assets are simply defined as geomorphological mediums (framework, support), without any cultural value (e.g. rock glacier destroyed by ski tracks creation). in a context of tourist development, the exploitation of this type of feature (c) creates a tourist and economic resource (with extensive or intensive use); without exploitation, landforms can simply be called geomorphological mediums. for all the six classes, natural and/or anthropic transformation (d) may happen due to tourist activities and infrastructures or geomorphological processes and hazards. thus, tourist projects may affect the geomorphological sites and mediums, creating direct, indirect or induced impacts and risks (after cavallin et al., 1994). j.p. pralong & e. reynard fig. 4 classification of geomorphological sites according to their values in a context of tourist development. classificazione dei siti geomorfologici secondo i loro valori in un contesto di sviluppo turistico. 319 5. application examples the proposed classification (fig. 4) may be used for assessing sustainability of tourist use of geomorphological sites. two examples in the area of chamonix-mont-blanc (haute-savoie, france) are proposed here as application examples of differential exploitation: the mer de glace glacier and the bossons glacier (see fig. 1 for location). this comparison may be interesting to illustrate the range between a “tourist and economic resource (with extensive or intensive use)” and a “tourist and cultural resource (with extensive or intensive use)”. 5.1. case study 1: the mer de glace glacier the montenvers is the final station (1930 m) of a mountain train allowing the access to a wonderful viewpoint of the mer de glace glacier (40 km2) which is the third largest glacier in the alps in terms of volume (moreau & vivian, 2000) after the aletsch glacier (120 km2, valais, switzerland) and the gorner glacier (65 km2, valais, switzerland). from the montenvers station, the access to the mer de glace is possible by a cable car, very impressive in terms of visual impact, or on foot by an established path. the tourist attractions linked to the glacier (fig. 5) are a glacial cave (on the right), dug out each spring and autumn for numerous years because of the glacier advance, and an “ice garden” (on the left), a space of pedestrian discovery allowing a walk on a small part of the glacier. in practice, there is a fee to visit the two attractions, which require a daily maintenance in reason of the glacial flow and the abundance of visitors (sometimes near to 6.000 per day according to ballu, 2002). inside the cave, some rooms and elements of the traditional and regional mountain way of life have been carved out (kitchen, bedroom, bathroom, lounge). furthermore, it is possible to have a photo taken with beethoven, a st-bernard dog, with a little typical “chalet savoyard” behind it. the walk is regulated by path boards and ends with the cave. no explanation about the glacial dynamic or the ice structure is proposed during the visit. only a tourist leaflet about the cave and the montenvers site is available at the cash-box, indicated by a signal board only visible after the visit! concerning the “ice garden”, created in summer 2002, the access is possible by the bridge of the cave (fig. 5). then, tourists can walk freely on a part of the glacier measuring about 30 meters by 70 meters, where a lot of glacial forms and micro-forms are visible (erratic blocks, supraglacial moraine, ice sheets, dirt cones, moulin, etc.). as in the cave, there are no explanations (didactic paths, leaflets, or guided visits) about these landforms and the glacier. furthermore, advertisements about this spot are so limited (e.g. just a few brochures are available at the railway station in chamonix), that this new recreational offer is considered by some tourists as a work site! in comparison with the number of people visiting the cave, few people are interested by this spot which, on the one hand, is completely secure (presence of hazard signboards, carpet on the ice, barriers limiting the space) and on the other hand, has not had the entry price to the site enhanced since its making. so, for the actors managing the site (cave and “ice garden” included), the aim of the exploitation is not to give didactic and cultural information, but to welcome a maximum of people in a profit earning logic, especially during the period of high abundance (summer season). in this case, the primary offer (natural glacier) has become less important in terms of exploitation than the secondary offer (artificial glacial cave, “ice garden”, cable car, established paths). the tourist value of the glacier seems to have been emptied of its cultural and scientific values by the economic value in an intensive and “uncultural” manner. but the impacts on the glacier (and not in the surroundings) are not necessarily negative and give a new scenic and cultural value to the mer de glace. thus, by a tourist landscape evolution, these new values have created a geomorphological landform of a second generation. 5.2. case study 2: the bossons glacier the bossons glacier one of the rare large white glaciers in the alps (fig. 6) is the longest glacial slope in europe (3500 m), with a tongue flowing down to 1350 meters (mollier, 2000). a proposal for a classification ... fig. 5 mer de glace glacier with its numerous artificial caves and its “ice garden”. chamonixmont-blanc (haute-savoie, france). ghiacciaio del mer de glace con numerose grotte artificiali e il suo “giardino glaciale” chamonix-mont-blanc (alta savoia, francia). 320 one of the best tourist viewpoints to see the glacier is the “chalet du glacier des bossons” (1425 m) which is a little restaurant accessible by a little cable car or on foot from the bossons village. the restaurant is built on the left lateral little ice age moraine of the bossons glacier, and composed especially by erratic blocks of granite from the mont-blanc unit. in summer, the tourist attraction is the sight of the glacier front, which presents a wonderful white colour and frequent ice avalanches. from the “chalet du glacier des bossons”, two viewpoints (gratis) can be reached; the first one at 1425 meters and the second one at about 1460 meters. a didactic path (with 10 boards) allowing the glacial flow and history and movements of the bossons glacier to be understood embellishes the ascension to the last viewpoint. concerning the didactic path, the pathway is quite inclined and narrow. furthermore, each board is an unprofessional set-up of copies of scientific books (texts and pictures) and the content apparently interests visitors who go to the viewpoint. finally, some didactic leaflets about the bossons glacier, perhaps used as tools for guided and cultural visits, are available for sale at the kiosk of the restaurant. thus, this tourist attraction was not created for an important abundance – as is actually the ice cave of the mer de glace glacier and is an example of extensive and cultural site exploitation. furthermore, visits do not create vulnerability, risk and impacts in relation to the glacier, because it is impossible to access to its (dangerous) front and to walk on and into the glacier2. in comparison with the montenvers site, the bossons glacier is completely different in terms of slope, colour and features, and also in terms of the use of values, risk and impacts, because, for the actors managing the site, the aim of the exploitation is to deliberately propose another way to discover a famous glacier. here, the economic value of the glacial landform is used without trashing its scientific and cultural values. finally, in this case, the primary offer (natural glacier) remains more important in terms of exploitation than the secondary offer (restaurant, pathway, didactic path, viewpoint). the tourist landscape evolution is more natural and the glacier has not really acquired a new scenic and cultural value (no value renewal), and also remains a geomorphological landform of the first generation. 6. conclusion in the relationships between geomorphology and tourist and recreational activities, three main elements are necessary to be studied: geomorphological sites optimization and exploitation, environmental impacts and natural risks. our study has especially considered the first one. for an understanding of the tourist and cultural evolution of landscapes and geomorphological sites, a step-by-step reflection in terms of optimization, exploitation and transformation is relevant. the proposed classification, depending on the scenic, scientific, cultural/historical, and social/economic value of the geomorphological items is based on this idea and shows three categories of geomorphological sites (geomorphological sites in both the strict sense and the broader sense) and geomorphological mediums segregated by the economic value. this method may be interesting for analysing the differential uses of geomorphological sites. we assume that the degree and the modalities of exploitation follow the various values given to geomorphological sites; the comparison between the mer de glace (tourist and economic resource) and the bossons glaciers (tourist and cultural resource) is in this way exemplary. the two examples (both concerning the chamonix area, haute-savoie, france) show that the differences in terms of geomorphological sites optimization and exploitation, environmental impacts and natural risks are not well understood in the simple distinction between soft and hard tourism, because tourist landscape evolution is influenced by a single j.p. pralong & e. reynard 2 before the age of mass tourism, there was a tourist ice cave into the bossons glacier. now, some guided visits are organised for walking on the glacier. fig. 6 front of the bossons glacier from the viewpoint of the “chalet du glacier des bossons”. chamonix-mont-blanc (haute-savoie, france). fronte del bossons ghiacciaio visto dal “chalet du glacier des bossons”. chamonix-montblanc (alta savoia, francia). human perception of the actors. such evolution can create different generations of geomorphological sites, whose values evolve. finally, a statement can be done: when the geomorphological resource becomes just a consumable product, the exploitation seems to be more oriented on the secondary offer and the impacts and risks are higher. also, less the actors managing the geomorphological resource take the scientific and cultural value into account, more the renewal of the resource tends to decrease. acknowledgements we strongly acknowledge our colleagues geomorphologists at the institute of geography of the university of lausanne, especially n. summermatter, for their useful comments, as well as the helpful criticisms of two anonymous reviewers. references ballu y. (2002) drus, montenvers et mer de glace paris, hoëbeke, 141 pp. barras c.v. (1987) le développement régional à motricité touristique. de la région polarisée à la région-système documents économiques, 33, fribourg, editions universitaires, 285 pp. cavallin a., marchetti m., panizza m. & soldati m. (1994) the role of geomorphology in environmental impact assessment geomorphology, 9, pp. 143-153. debarbieux b. (1995) tourisme et montagne paris, economica, 107 pp. debarbieux b. (2000) bilan critique de 50 ans de tourisme à chamonix rapport n° 1, urbanisation aménagement, politiques touristiques, représentation sociales (http://www.sommets-tourisme.org). dorthe-monachon c. (1986) contribution à l'étude de la morphologie glaciaire de la vallée de l'arve (haute-savoie, france) : essai de reconstitution paléogéographique thèse de doctorat présentée à la faculté des lettres de l’université de lausanne, 249 pp. espace mont-blanc (2001) 50 sentiers à thèmes dans l’espace mont-blanc. haute-savoie, savoie, valais, vallée d’aoste, grenoble, glénat, 239 pp. mollier c. (2000) du glacier du mont-blanc au glacier des bossons yens, cabédita, 131 pp. moreau l. & vivian r. (2000) dans le secret des glaciers du mont-blanc grenoble, glénat, 95 pp. panizza m. (2003) géomorphologie et tourisme dans un paysage culturel intégré in: e. reynard, c. holzmann, d. guex & n. summermatter (eds.), géomorphologie et tourisme, actes de la réunion annuelle de la société suisse de géomorphologie (ssgm), finhaut, 21-23 septembre 2001, lausanne, institut de géographie, travaux et recherches, 24, pp. 11-20. panizza m. & piacente s. (1993) geomorphological assets evaluation zeitschr. für geomorphologie n.f., suppl. bd., 87, pp. 13-18. panizza m. & piacente s. (2003) geomorfologia culturale bologna, pitagora, 350 pp. quaranta g. (1993) geomorphological assets : conceptual aspect and application in the area of crodo da lago (cortina d’ampezzo, dolomites) first european intensive course on applied geomorphology, proceedings, modena cortina d’ampezzo 24 june 3 july 1992, pp. 49-60. r eynard e., h olzmann c. & g uex d. (2003) géomorphologie et tourisme: quelles relations? in: e. reynard, c. holzmann, d. guex & n. summermatter (eds.), géomorphologie et tourisme, actes de la réunion annuelle de la société suisse de géomorphologie (ssgm), finhaut, 2123 septembre 2001, lausanne, institut de géographie, travaux et recherches, 24, pp. 1-10. 321a proposal for a classification ... imp.farabollini& proposal for preservation and protection of the marche region mud volcanoes (central italy) piero farabollini1, marco materazzi1 & gianni scalella2 1dipartimento di scienze della terra università di camerino 2professional geologist via vezzelli, 1 63025 montegiorgio (ap) abstract: p. farabollini et al., proposal for preservation and protection of the marche region mud volcanoes (central italy). (it issn 0394-3356, 2005). have been in the past the subject of several studies by different authors; mentioned in classical scripts, they have been treated more in detail starting from the 17th century in naturalistic studies published by scientific academies or cultural associations. in the marchean region, these phenomena have been observed only in the peri-adriatic sector where pliocene and pleistocene formations crop out; they are well represented with respect to typology, number and extension. the present paper proposes several strategies for their preservation and protection: in particular these aim to avoid the characteristic morphologies, produced by leaking mud (also several times per year in some cases), being suddenly demolished by anthropic or natural agents. mud leakage generally occurs on a flat surface called “piano della salsa” prevalently on a thalweg or along a very gentle portion of the slope. typical, in mud volcano morphology, is the presence of one or more cones of different height and extension with emission of mud with different fluidity; sometimes natural boundaries exist and the leakage remains confined inside a depression, but in other cases the mud emissions can reach the hydrographic network. the marches region administration, as those of other italian regions, have no rules yet (except for some indications in the pparregional plan for landscape and the environment) for preventing and protecting these geo-sites. the procedure for safeguarding them should start from an analysis of the territory and a study of its resources, in particular defining characteristics, potential risks, and the objectives to be reached; in addition, it should formulate proposals for their use and enhancement, also indicating possible thematic routes (geological and geomorphologic pathways) in particularly significant areas. riassunto: p. farabollini et al., proposte per la conservazione e tutela dei vulcanelli di fango delle marche (italia centrale). (it issn 0394-3356, 2005). i “vulcani di fango” o “vulcanelli di fango” o “salse”, sono stati oggetto, in passato, di studi da parte di numerosi autori; se ne ritrovano tracce a partire dagli scrittori classici e, più diffusamente, dal ‘600 in poi con la ripresa dell’attività conoscitiva degli aspetti naturalistici da parte delle accademie scientifiche e delle associazioni culturali. i vulcanelli di fango, nella loro configurazione tipica, sono stati osservati nella regione marchigiana solamente nell’area periadriatica, caratterizzata dall’affioramento di depositi terrigeni pliocenici, anche se ben rappresentati, sia come tipologia che come numero che come estensione. per citarne solamente i maggiori, si ricordano quelli presenti nelle marche centro-settentrionali, nei pressi di maiolati spontini (an) e san paolo di jesi (an); oppure quelli nelle marche centro-meridionali presenti nei pressi di petriolo e loro piceno (mc), nei pressi di montegiorgio (ap), falerone (ap), offida (ap) e nelle vicinanze del monte dell’ascensione (ap). nel presente lavoro, oltre a riportare alcuni dati desunti da osservazioni effettuate sui vulcanelli di fango dell’area delle marche meridionali (offida), si propongono alcune azioni volte alla loro conservazione e tutela in quanto, nonostante le emissioni si ripetano per diverse volte nell’arco di un anno, anche se in maniera discontinua nel corso di più anni, le forme originate dal fango fuoriuscito, vengono quasi sempre demolite dagli agenti esogeni e, soprattutto, dall’azione dell’uomo, pochissimo tempo dopo la loro formazione. le emissioni fangose avvengono in genere su una superficie pianeggiante chiamata “piano della salsa”; in quasi tutti i casi osservati, esse risultano presenti sul fondovalle e/o su superfici pianeggianti che interrompono il pendio e indipendente dal reticolo idrografico presente; tuttavia non mancano casi, peraltro molto rari, in cui invece è possibile osservarle lungo il talweg del reticolo idrografico secondario. la regione marche, così come la quasi totalità delle regioni italiane, ad eccezione di alcune indicazioni contenute nel cosiddetto ppar (piano paesistico ambientale regionale), non è dotata di norme che prevedano in qualche modo azioni di conservazione e tutela di tali geositi. il procedimento per giungere alla salvaguardia dei geosito dei “vulcanelli di fango”, e delle aree ad esse connesse, dovrebbe prendere inizio dalla fase di analisi del territorio e delle sue risorse, che valuti le aree in base agli aspetti di ogni singolo sito ed alla sua vocazione, individui le minacce e ne definisca gli obiettivi da perseguire e che, infine, indichi le proposte di fruizione e valorizzazione di ogni geosito, includendo anche la possibilità di individuare percorsi tematici specifici (sentieristica geologico-geomorfologica) per zone particolarmente significative. tale piano potrebbe risultare composto dalle seguenti fasi: • fase di analisi; • fase di valutazione e definizione; • fase propositiva (di tutela e di valorizzazione). in particolare, gli strumenti per la tutela e la gestione di questo peculiare geosito potrebbero essere rappresentati da: • ripristino delle condizioni naturali dell’affioramento e promozione di attività di conservazione del geosito; • pannelli di avvicinamento e/o segnalazione del luogo mentre, sul posto, pannelli interpretativi che spiegano il fenomeno che si ha davanti, la sua genesi e la sua evoluzione spazio-temporale, anche con ricostruzioni 3d del suo stato iniziale confrontato con quello attuale; • zona di sosta, supportata da idonea tabellazione esplicativa, strutturata in maniera tale da rappresentare un polo di attrazione alla stessa stregua di un museo naturale all’aperto. key words: mud volcanoes, pliocene sediments, periadriatic area, defence and preservation, marches region. parole chiave: vulcanelli di fango, sedimenti pliocenici, fascia periadriatica, tutela e conservazione, regione marche. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 179-184 180 p. farabollini et al. 1. introduction mud volcanoes (also known as “vulcanelli di fango”, “salse”, “maccalube”, or “bollitori”) have always been the object of study, both on account of their particular conformation and morphology and of the curiosity and, in some cases, the fear that they can cause in society. mention of them can be found in works by classical writers (marinelli, 1904; biasutti, 1907; bonasera, 1952; damiani, 1964), and more widespread accounts are present beginning from the 17th century with the revival of interest in natural phenomena on the part of scientific academies and cultural associations. to explain the genesis of these phenomena, which can display different morphological aspects and characteristics according to different geological and hydrogeological conditions, various hypotheses have been put forward regarding the regional seismic activity, the presence of gas, the rainfall regime, the morphological and geohydrological conditions of the area surrounding the mud volcanoes, etc. (marinelli, 1904; biasutti, 1907; bonasera, 1952; damiani, 1964; nanni & zuppi, 1986; martinelli, 1999; scalella, 2000). more in particular the presence of these phenomena in the area, has been related (bonasera, 1952; damiani, 1964; nanni & zuppi, 1986), to the uprising of deep hot waters along preferential lines (faults and/or joint systems, structural boundaries, etc.). in their typical configuration, the mud volcanoes in the marches region have been observed only in pliocene sediments; to mention only the major phenomena: those in the central-northern marches are in the neighborhood of maiolati spontini and s. paolo di jesi (in the province of ancona); those in the centralsouthern marches are near petriolo and loro piceno (province of macerata), and montegiorgio, falerone, offida and the monte dell’ascensione (province of ascoli piceno). the mud volcanoes present in offida area (province of ascoli piceno) are studied and described in this paper. moreover it proposes several strategies for the preservation and protection of the marche region mud volcanoes (fig.1). the presence of these mud-emission vents offers a wide view of the different mud volcano morphologies and typologies, which even though not presenting particularly exciting characteristics, all the same are an environmental heritage which is extremely vulnerable, above all since the ever increasing anthropic activity, especially of an agricultural kind, is rapidly canceling it. 2. geological and hydrogeological setting of the marche region mud volcanoes mud volcanoes have only been found in the periadriatic area where pliocene-pleistocene terrigenous deposits exclusively crop out. from the geological standpoint, the peri-adriatic area is characterized by a stratigraphic succession typical of one or more transgressive-regressive cycles, made up of alternations of conglomeratic, arenaceous, and arenaceous-pelitic deposits, often with considerable facies variation, both laterally-vertically and longitudinally in transgressive contact, with frequent onlap joints, with pliocene pelitic and pelitic-arenaceous deposits cropping out in the innermost areas (centamore & deiana, 1986; ori et al., 1991). the thickness of the deposits, also determined during petroleum and hydrogelogical prospecting research (eni, 1972), reaches 1500 to 2000 m in the westernmost portion and 3500 to 4000 m in the easternmost one. this sedimentary succession represents the foredeep filling sediments, migrating little by little eastward, or else piggy-back-type basins (ori et al., 1986; ori et al., 1991). it is affected by small-sized thrusts placed on the top of the carbonatic succession, if not indeed inside the pliocene deposits themselves (argnani et al., 1991). in the majority of cases, these are not outcropping thrusts, and so at the surface the setting is almost always a monoclinal one (fig. 2). however, some positive structures are present, such as the polverigi anticline and the so-called coastal ridge which includes, amongst other things, the conero and porto san giorgio structures (bigi et al., 1995). the quaternary tectonic activity can be identified above all in the quaternary deposits that closed the plio-pleistocene cycle; these, in addition to displaying considerable reduction in the thickness of the series in the proximity of the anticline structures (porto san giorgio), prove to be dislocated both by direct and inverse faults. from the hydrogeological standpoint, the system of folds, faults, thrusts, and fracture zones that characterizes all the peri-adriatic area, gives rise to a complex geological-structural feature from which are derived different smalland large-scale hydrogeological structufig. 1 – location of mud volcanoes in the marches region and in the offida area. black line indicates the stratigraphic transition from the miocene to the plio-pleistocene. white triangles indicate main areas affected by mud vent phenomena. ubicazione dei vulcanelli di fango della regione marche e dell’area di offida. la linea nera rappresenta il passaggio stratigrafico miocene-plio/pleistocene. i triangoli bianchi indicano le maggiori aree di emergenza dei vulcanelli di fango. 181proposal for preservation ... res. the former can give rise to surface-type water circulation, considerably variable both in trend and amount, conditioned by prevalently local morphological and bedding factors; instead, the latter generally generate a deeper regional-type circulation, uniform in direction of flow and amount, and mainly regulated by tectonic and structural factors. with respect to water springs, in the stratigraphic sequences characterized by intercalations of arenaceous, arenaceous-conglomeratic, arenaceous-pelitic, and pelitic-arenaceous units, the numerous perennial water springs testify to the presence of aquifers inside the permeable units and that are mainly filled by rainfall (scalella, 1996; nanni & vivalda, 1998). as for the structural setting, the water circulation in the arenaceous horizons can even reach considerable depths and come into contact with the brackish and salt waters present in the miocene and pliocene deposits (eni, 1972). according to some authors (nanni & zuppi, 1986; nanni & vivalda, 1998), arenaceous bodies belonging to the lower and middle pliocene sequence are frequently saturated with brackish and salt waters, and more rarely with freshwater, while the latter prevails in pleistocene deposits. 3. morphological characteristics of the mud vent phenomena in the offida area the mud vent phenomena and other characteristic morphological features (flows, fractures, cones, etc.) are essentially found in the fosso del lago valley bottom, in the point where the bed widens out and displays a decidedly asymmetric shape due to the monoclinal bedding of the bedrock (fig. 3). generally, this area, notwithstanding the considerable farming activities practiced there, can almost always be recognized by its vegetation which, at the point of mud emission, is always more luxuriant, due to the water permanence. the mud volcano morphology is extremely variable and in continuous evolution. long-term observations, apart from evidencing a more intense activity in the periods of greater rainfall, have shown that with the passing of the years new mud vents can open up, at times with the formation of new small cones. in particular, for almost all the phenomena observed in the marches region, the morphology of the areas with mud volcanoes is characterized by the existence of a zone where one or more emission point(s) are located (with the presence of emitted mud) and by one or more small cones of different height and extent, at the summit of which mud of varying fluidity is emitted (fig. 4). mud emission generally occurs over a flat surface, called “piano della salsa”; in most cases, it occurs on the valley bottom and/or on nearly flat morphologies that interrupt the slope. it generally leads to the formation of a cone, usually circular in shape, to the presence of topographic surfaces with reduced angle of slope, and with a good speed of emission and a fair density of mud emitted. in some cases, when their density is higher, the emission itself, is confined inside a depression that prevents its propagating, whereas in others it develops by means of flows that sometimes ends upfi g . 2 – s c h e m a ti c g e o lo g ic a l c ro ss s e c ti o n o f th e p e ri -a d ri a ti c a re a : m = m e ss in ia n ; p 1 = l o w e r p lio c e n e ; p 2 = m id d le p lio c e n e ; p 3 = u p p e r p lio c e n e ; q = q u a te rn a ry ( m o d ifi e d f ro m s c a le lla , 1 9 9 6 ). s e zi o n e g e o lo g ic a sc h e m at ic a d e ll’ ar e a p e ri ad ri at ic a: m m e ss in ia n o ; p 1 p lio c e n e in fe ri o re ; p 2 p lio c e n e m e d io ; p 3 p lio c e n e s u p e ri o re ; q q u at e rn ar io ( m o d ifi c at a d a s c al e lla , 1 9 9 6 ). 182 into the hydrographic network. often, the landforms originating from the mud emitted, above all due to their intermittent nature, are demolished by external agents and above all by the action of man (fig. 3). in addition to displaying varying size, the mud volcanoes in the study area are characterized by an intermittent activity with time intervals even of a few years between one emission and another. this activity means that whenever the phenomenon occurs, it is immediately remodeled by anthropic activity that, for agricultural purposes, tends to restore a surface that can be utilized within a brief period of time. in fact, for many of the situations occurring in the marches region, the immediate actions of man have always prevented the development of these phenomena, and even canceled the least evidence of such activity, and at times not even allowing the formation of new emissions. 4. hypotheses of fencing, management, and safeguarding of the mud volcano areas of marche region in this context of an extremely various typology of mud volcanoes present in the marches region territory, we wish to propose certain actions aimed at preserving and safeguarding them, also on the basis of what has been done for those in the municipality of fiorano modenese, where specific regional regulations in 1982 set up the natural reserve of “salse di nirano”. the marches region, as almost all the other italian regions, with the exception of certain guidelines contained in the law called ppar, is not equipped with legislation that foresees in some way actions of preservation and safeguard for these geosites. however, inspired by the above-mentioned laws, the marches region has published a volume “le emergenze geologiche e geomorphologiche della regione marche” (geological and geomorphologic emergency in the marches) (various authors, 1991) in which the geosites were listed, using very simplified and easy-to-read census forms, as an important characteristic element of the marchean geological and geomorphological landscape, and thus worthy of being “respected”. in addition to these actions of characterizing the geosites, establishing them at a level of geological diversity (bertacchini et al., 1999; farabollini et al., 2002; sampaolesi & farabollini, 2002), and spreading information on them, it is of paramount importance to identify specific actions aimed at: • restoring natural outcrop conditions; • promoting activities to preserve the geosites; • defining specific regional legislation for preserving and safeguarding them. with the aim of attaining a really binding set of legislation for preserving these particular features, a greater awareness of their importance, but above all of their fragility, is obviously needed, not only on the part of technicians and administrators operating in the field of territorial planning, but also on that of the social community itself. the procedure to be followed for achieving an adequate safeguard of the geosites in question should start from the phase of analyses of the territory and its resources, such as to assess the area on the basis of the aspects and utilization potential of each site, identifying the threats and defining the objectives to pursue, and, finally, indicating the proposed means of exploiting and appraising it. the last of these stages would deal with the possibility of identifying specific thematic routes (geological-geomorphological trails) for the particularly significant ones, both from the tourist and educational-scientific standpoints. thus, each individual area characterized by the presence of mud volcanoes could be defined, in zones of various levels of environmental protection: fig. 3 – panoramic view of mud volcanoes area of offida (june 1996). the considerable farming activity should be noted; this led to the disappearance of the mud volcano morphology, even though it can still be recognized by the more luxuriant vegetation due to the water permanence. foto panoramica delle zone dei vulcanelli di fango di offida (giugno 1996); da evidenziare la notevole attività antropica che ha portato alla scomparsa della morfologia del vulcanello di fango, anche se riconoscibile a causa della vegetazione più lussureggiante dovuta a ristagni di acqua. p. farabollini et al. 183 1. areas of total protection: to be set up exclusively in a significant setting where mud volcanoes can evolve naturally; in these areas, all types of activity would be forbidden. 2. areas of planned protection: these areas would include the previous group, and only those activities for conserving, managing and appraising the geosite would be allowed. 3. protected areas: these would include the areas of the previous two groups and aim at a more significant outward-going context in which non-destructive farming activities would be permitted. the above-mentioned proposal to fence the areas implies that the owners of the land where the geosite is located, and all the protected areas, should keep more or less large areas of land uncultivated, and additional farming practices should be carried out with respect to those followed beforehand (for instance, a different drainage pattern for collecting rainwater would be required). therefore, the legislation could contain norms for safeguarding the rights of the owners, with funds aiming at compensating them for any loss of income and/or additional expenses they had to meet due to modified farming practices. in this way, also for the mud volcanoes in the marches, a specific legislation would be set up aimed at safeguarding and preserving, so that these geosites that for years have had the role of being “prodigious natural phenomena”, will not disappear for ever, not even from human memory. references argnani a., artoni a., ori g.c. & roveri m. (1991) l’avanfossa centro-adriatica: stili strutturali e sedimentazione studi geol. camerti, vol. spec. crop 03, pp. 371-381. bertacchini m., giusti c., marchetti m., panizza m. & pellegrini m. (eds.) (1999) i beni geologici della provincia di modena artioli ed., modena, 104 pp. biasutti r. (1907) le salse dell’appennino settentrionale memorie geografiche, 2, pp. 7-255. b onasera f. (1952) i vulcanelli di fango del preappennino marchigiano riv. geogr. it., lix, 1, pp. 16-26. centamore e. & deiana g. (1986) la geologia delle marche studi geol. camerti, vol. spec., 210 pp. damiani a.v. (1964) studio della salsa di offida (ascoli piceno marche) l’universo, xliv, 3, pp. 473488. eni (1972) acque dolci sotterranee. inventario dei dati raccolti dall’agip durante la ricerca di idrocarburi in italia ed. eni, roma. farabollini p., materazzi m. & scalella g. (2002) mud volcanoes in central-southern marche (italy): proposals for their bounding, enhancing, preservation and protection from extinction in: p. coratza & m. marchetti (eds.) (2002), geomorphological sites: research, assessment and improvement, proceedings of the workshop held in modena, italy, on june 19-22, 2002, legoprint, lavis (tn), pp.110. farabollini p., materazzi m. & scalella g. (2002) ifi g . 4 – d e ta il o f m u d v o lc a n o e s in t h e o ff id a a re a ( a re a o f th e f ig u re 3 ): t h e m u d e m it te d b e tw e e n d e c e m b e r 1 9 5 9 a n d m a rc h 1 9 6 0 t o g e th e r w it h t h e r e la ti ve m o rp h o lo g y (a ft e r d a m ia n i, 1 9 6 4 ). d e tt ag lio d e i v u lc an e lli d i f an g o d e ll’ ar e a d i o ff id a (a re a d e lla f ig u ra 3 ): e m is si o n e d i f an g h i a vv e n u ta t ra il d ic e m b re 1 9 5 9 e d il m ar zo 1 9 6 0 e r e la ti va m o rf o lo g ia ( d a d am ia n i, 1 9 6 4 ). proposal for preservation ... 184 “vulcanelli di fango” della regione marche: proposte di perimetrazione, valorizzazione, conservazione e tutela di aree a rischio di estinzione atti conv. genova, 27-29 giugno 2002, geologia dell’ambiente, in stampa. marinelli o. (1904) i bollitori di san paolo di jesi l’appennino centrale, 1, 9 pp. martinelli g. (1999) mud volcanoes of italy: a review. giorn. geol., ser. 3, vol. 61, pp. 107-113. nanni t. & vivalda p. (1998) le acque salate dell’avanfossa marchigiana: origine, chimismo e caratteri strutturali delle zone di emergenza boll. soc. geol. it., 118, pp. 191-215. nanni t. & zuppi g.m. (1986) acque salate e circolazione profonda in relazione all’assetto strutturale del fronte adriatico e padano dell’appennino mem. soc. geol. it., 35, pp. 979-986. ori g.c., serafini g., visentin c., ricci lucchi f., casnedi r., colalongo m.l. & mosna s. (1991) the plio-pleistocene adriatic foredeep (marche and abruzzo, italy): an integrated approach to surface and subsurface geology 3rd e.a.p.g. conf., florence, 85 pp. sampaolesi s. & farabollini p. (2002) la conservazione e la tutela dei geositi: l’esempio della piramide di terra nel parco nazionale dei monti sibillini (marche centro-meridionali) geologia dell’ambiente, 2, pp. 28-37. scalella g. (1996) geomorfologia e geologia ambientale di un tratto del medio bacino del fiume tenna: correlazioni con il medio bacino del torrente tesi di laurea inedita università di camerino. scalella g. (2000) analisi geomorfologiche in aree interessate da neotettonica: appennino umbromarchigiano e fascia periadriatica tesi di dottorato inedita – università di perugia. various authors (1991) le emergenze geologiche e geomorfologiche delle marche regione marchegiunta regionale, ancona. p. farabollini et al. imp.cattuto_gregori& condizioni geomorfologiche e stabilita’ dell’acropoli di tarquinia vecchia c. cattuto 1, l. gregori 1, m. milano 2 & s. rapicetta 1 1 dipartimento di scienze della terra università degli studi di perugia 2 collaboratore esterno piazza università, 1 06123 perugia cattuto@unipg.it; lucilia@unipg.it; silviarap&gmail.com riassunto: c. cattuto, l. gregori, m. milano & s. rapicetta, condizioni geomorfologiche e stabilità dell’acropoli di tarquinia vecchia. (it issn 0394-3356, 2007). circa 5 km a ne dell’odierna tarquinia, si erge una collina la cui sommità è costituita da un’ampia placca calcarea, limitata da una scarpata di circa 5/10 m, che poggia su una potente pila di argille. gli scavi condotti sulla collina hanno messo in luce i resti dell’acropoli dell’antica tarquinia etrusca. tuttavia i numerosi ed interessanti reperti scavati, sono minacciati da vari fenomeni: il cedimento e/o il crollo conseguente la dissoluzione e la carsificazione delle rocce calcaree sulle quali sono fondati, l’erosione il trasporto e la sedimentazione di materiale argillosabbioso operata dal ruscellamento incontrollato delle acque meteoriche, il crollo, per mancanza di sostegno al piede, dei reperti ubicati lungo il bordo della scarpata che limita l’area degli scavi, la frequente variazione del comportamento geomeccanico imposta, dalle pratiche agricole, ai terreni argillosi affioranti al piede della placca calcarea. sulla base delle caratteristiche rilevate, vengono illustrate le condizioni geomorfologiche d’insieme indicando, sommariamente, una serie di possibili interventi tesi a mitigare il pericolo di perdita o di inagibilità dei reperti venuti alla luce in molti anni di scavi e che costituiscono un patrimonio storico artistico e culturale assolutamente unico. abstract: c. cattuto, l. gregori, m. milano & s. rapicetta, geomorphologic conditions and stability of the acropoli “tarquinia vecchia”. (it issn 0394-3356, 2007). in this paper a study about lithologic and geomorphologic characteristics of the archaeological area of tarcxuna, the ancient tarquinia city, in the viterbo district (lazio region, central italy) is presented. the above mentioned archaeological area is situated on the sub-horizontal top of a hill, and it is limited by a high limestone escarpment. in this area, the acropoli, many archaeological objects have been recovered, among them the famous terracotta named "cavalli alati" that comes from the front of the temple. the lithostratigraphical sequence comprises of a high pile of “argille azzurre”, of the low-medium pliocene, then there are two formations of medium-top pliocene, in lateral facies eteropy: “calcare di tarquinia”, limestone of 30 meters of maximum height, and the “sabbie gialle”. the “calcare di tarquinia” (famous also as macco) has a sub-horizontal order and it constitutes the base on which a great part of the acropoli of “tarquinia vecchia” rises and the limestone escarpment that limits the archaeological area too. the limestone is fractured-karst rock and the waters that cross it constitute aquifers that fill small sources at contact with the “argille azzurre”. the clay slides and so remove the support to the limestone escarpment that collapse in blocks also large dimensions. the regression of the escarpment is favoured by the agricultural activity, that is realized carried out until the base of the escarpment. the above mentioned regression affect the “argille gialle” that are over, therefore in more points, there are landslides that induce the collapse of some areas of the tarquinia vecchia town-walls. in order to mitigate the landslide risk in the archaeological area, it is necessary: to stop the rill erosion, to reduce the infiltration, to capture and to remove the waters emerging at the base of the limestone escarpment, to create structures able to control and to support the base of the escarpment. parole chiave: geoarcheologia, geomorfologia, lazio, tarquinia keywords: geoarcheology, geomorphology, lazio region, tarquinia. il quaternario italian journal of quaternary sciences 19(2), 2006 227-232 l’area di studio la città di tarquinia è nota nel mondo per i reperti della civiltà etrusca, in particolare per le numerose tombe (circa 150), decorate con pregevoli pitture, rinvenute a sudest del centro abitato, nella “necropoli di monterozzi” lungo lo spartiacque meridionale del f.so s. savino (fig. 1). lungo il crinale opposto, circa 5 km a ne dall’attuale tarquinia, sorgeva il centro abitato di “tarcxuna”, l’antica tarquinia (ix-viii sec. a. c.), che occupava la sommità subpianeggiante di un colle, limitata da un’alta scarpata calcarea. dell’acropoli restano numerose testimonianze (fig. 2) ed è ancora visibile parte della cinta muraria edificata in blocchi calcarei, che sembra risalire al v sec. a.c. (bonghi j.m., 1986). nell’area più elevata del rilievo, inoltre, sono stati messi in luce i resti di un tempio, l’ara della regina, forse il più grande dell’etruria, dal quale provengono i famosi “cavalli alati” in terracotta che ne decoravano il frontone (fig. 3). 228 c. cattuto et al. caratteristiche geologiche del territorio dopo la crisi salina del miocene, che ha lasciato ampie tracce in alcune aree del tarquinese e della toscana meridionale, la tettonica distensiva, con sistemi di faglie a direzione appenninica, disarticola il margine tirrenico tosco-laziale creando ampi bacini (back basins). l’ingressione marina che si accompagna alla subsidenza di questo territorio raggiunge il massimo approfondimento (fregni et alii, 1985) in due bacini separati dai monti della tolfa: a sud il “bacino romano”, a nord il “bacino del fiora” (f a z z i n i et alii, 1972). in questi ambienti epimesobatiali, che si estendono ad est fino alla catena appenninica, durante il pliocene inferiore e medio, si accumulano potenti coltri di sedimenti argillosi (argille di cerveteri nel bacino romano, argille azzurre in quello del fiora). come evidenziato dalla cartografia geologica di fig. 1 e dalla sezione schematizzata in fig. 4, nell’area di tarquinia vecchia affiora una potente formazione di peliti (circa 150 m di spessore), nota come argille azzurre o argille turchine (bellotti et alii, 1993). sopra le argille turchine, in eteropia di facies tra loro, si alternano sabbie gialle e calcareniti (bonadonna f.p., 1967). le sabbie gialle, a luoghi molto addensate e a tratti alternate con sabbie argillose o conglomeratiche, sono ricche in macrofaune (pectinidi, gasteropodi, ostreidi, ecc.) e raggiungono uno spessore m a s s i m o d i c i r c a 1 0 0 m . hanno prevalentemente un colore giallastro e sono riferite al pliocene medio-superiore. allo stesso periodo risalgono le calcareniti che, sfumano talora in calcari sabbiosi giallastri ma che, più spesso, si presentano in strati e banchi compatti e costituiscono il calcare di tarquinia (c h i o c c h i n i u., 1990), noto anche con il termine locale di “macco”. la potenza massima di questa formazione non supera i 30 m e, in virtù della sua facile lavorabilità, questa roccia è stata utilizzata, fin dal periodo etrusco, come materiale da costruzione. fig. 1 cartografia geologica schematica dell’area d’indagine: 1. isoipsa, 2. corso d’acqua, 3. strada principale, 4. scarpata, 5. limite litologico, 6. depositi alluvionali recenti, 7. sabbie gialle, 8. calcare di tarquinia (macco), 9. argille azzurre o turchine, sg traccia della sezione geologica schematizzata in fig. 4. geologic map of the study area: 1. contour line, 2. river stream, 3. main road, 4. escarpment, 5. lythologic boundary, 6. recent alluvial deposits, 7. yellow sand, 8. limestone of tarquinia (macco), 9. clay, sg cross section location shown in figure 4. fig. 2 cartografia schematica della superficie del colle, attorno all’isoipsa dei 150 m s.l.m. con la posizione dei resti archeologici più importanti di tarquinia vecchia, messi in luce dagli scavi. scheme map of the most important etruscan ruins of tarquinia; highlighted is the 150m contour line. 229condizioni geomorfologiche e stabilità dell’acropoli ... l’affioramento “a giropoggio” lungo l’intero versante meridionale del colle sul quale sono gli insediamenti di tarquinia vecchia e si identifica con la ripida scarpata, praticamente inaccessibile, alta in media dai 5 ai 15 m che circonda l’intero insediamento dell’antica tarquinia. nell’area di pian della civita le sabbie gialle sono state completamente erose e la sommità del rilievo (superficie strutturale) coincide con il tetto della formazione calcarea (fig. 5). condizioni geomorfologiche e stabilità dei siti archeologici sulle caratteristiche meccaniche delle rocce costituenti il territorio d’indagine si possono avanzare le seguenti considerazioni: 1. le sabbie gialle sono prevalentemente incoerenti o dotate di una modesta coesione indotta da processi pedogenetici o dalla presenza di matrice argill o s a . l a s t a b i l i t à d i q u e s t o materiale è pertanto dipendente dall’angolo di attrito interno che localmente può variare in funzione delle condizioni meteoclimatiche (grado di saturazione, processi di gelo-disgelo e/o di umidificazionee s s i c c a z i o n e ) , d a i p r o c e s s i e r o s i v i i n a t t o (riduzione/aumento degli spessori, scalzamento al piede), dall’attività antropica (aratura, zootecnia), ecc. (fig. 6). fig. 3 i “cavalli alati” (museo nazionale etrusco di tarquinia). “the winged horses” (etruscan national museum of tarquinia). fig. 4 sezione geologica schematica del rilievo di tarquinia vecchia. cross section of tarquinia ancient hill. fig. 5 la superficie strutturale formata dal calcare di tarquinia nell’area dell’acropoli di tarquinia vecchia. section of the acropolis of the ancient town showing the structural surface made of the limestone of tarquinia. fig. 6 il progressivo arretramento della scarpata calcarea interessa anche l’equilibrio delle sovrastanti sabbie gialle. the gradual moving back of the limestone escarpment involves the stability of the overlapping yellow sands. il macco riveste un importante ruolo geomorfologico; compreso, infatti, tra le sabbie gialle e le argille azzurre, cioè tra rocce facilmente erodibili, è portato ad “emergere” topograficamente per fenomeni di litoselezione. l’assetto suborizzontale, infine, ne determina 230 2. il calcare di tarquinia presenta caratteristiche sedimentologiche variabili sia verticalmente che orizzontalmente; coesistono e sfumano gli uni negli altri, addensamenti calcarenitici, strati calcareo-marnosi e livelli o lenti di limi sabbiosi, mentre la struttura e l’assetto generale sono in strati e banchi discontinui. il grado di fratturazione è molto elevato (fig 8) e l’infiltrazione delle acque praticamente totale e molto rapida. il comportamento meccanico della roccia varia pertanto anche su modesti volumi, mentre la dissoluzione risulta il processo morfogenetico più efficace (carsificazione). la generale stabilità della superficie strutturale calcarea (pian della civita) si interrompe lungo la scarpata che la delimita e che, ovviamente, risulta esposta al pericolo di crolli. 3. le argille azzurre manifestano un comportamento meccanico abbastanza omogeneo e costante su ampie superfici di affioramento, sono sovraconsolidate, dotate di una moderata coesione e la loro permeabilità è decisamente ridotta anche se, in superficie, lo strato d’alterazione ha un notevole spessore (frequentemente attorno al metro) e viene continuamente areato e rimosso dalle pratiche agricole. come più frequente conseguenza di queste, l’infiltrazione locale può aumentare fino a deteriorare le caratteristiche meccaniche dei materiali mettendone in crisi la stabilità (fig. 7). condizioni idrogeologiche la rapida circolazione delle acque attraverso il calcare di tarquinia viene fermata al contatto con le argille azzurre; entro i calcari si formano così accumuli idrici discontinui, in passato raggiunti anche dai pozzi messi in luce dagli scavi, che alimentano sorgenti perenni (una delle quali captata) o, più frequentemente, emergenze idriche temporanee. queste acque assumono un ruolo importante ai fini della stabilità dei siti archeologici: emergendo al contatto con le argille, ne mantengono elevato il grado di umidità, spesso fino alla completa saturazione. in fig. 7 l’attività antropica contribuisce alla destabilizzazione dei versanti; l’aratura facilita la saturazione del terreno, provocando fenomeni di ruscellamento e di frana. the human activity is a key factor of the slope stability, the ploughing activity leads to the high degree of soil saturation, raising the rill, gully erosion and landslides events. fig. 9 le argille azzurre sono affette da fenomeni franosi retrogressivi che si spingono fino al piede della scarpata calcarea; questa, priva di sostegno, crolla in blocchi anche di considerevole volume. the grey clay are affected by landslide movements moving upslope toward the foot of the limestone escarpment. due to this fact the escarpment falls down with blocks of large dimension. fig. 8 il calcare di tarquinia è profondamente e intensamente fratturato e la rapida e massiccia infiltrazione delle acque ne provoca la continua corrosione. the tarquinia limestone is deeply fractured and the fast infiltration causes the continuous corrosion. queste condizioni è facile che le argille raggiungano lo stato plastico e che si producano fenomeni gravitativi di vario tipo, più frequentemente scivolamenti e colamenti superficiali (fig. 9). c. cattuto et al. 231 il processo è favorito dall’uso agricolo del terreno argilloso; l’aratura a giropoggio viene infatti spinta fino alla base della scarpata calcarea, creando le condizioni per il ristagno delle acque, l’infiltrazione e la massima saturazione del terreno. pericolo per i siti archeologici nelle attuali condizioni il pericolo più grave per l’area degli scavi è quello derivante dal progressivo arretramento della scarpata calcarea (fig. 10) e dal crollo dei manufatti che la sovrastano. anche dove l’arretramento della scarpata rocciosa ha esposto all’erosione le sabbie sovrastanti, si stanno creando fenomeni di instabilità; il più evidente è quello che si è prodotto ai danni della cinta muraria della tarquinia antica, già crollata o direttamente minacciata in più punti (fig. 11) e per lunghe tratte ormai vistosamente inclinata e prossima al ribaltamento (fig. 12). negli anni passati la sommità del colle sul quale si estende l’antica tarquinia era intensamente coltivata e sono ancora visibili, sui blocchi di muratura semiaffioranti dal terreno, le scalfitture prodotte dal vomere. ad evitare la possibile rovina dei manufatti non ancora messi in luce dagli scavi, la stessa area è stata destinata a prato-pascolo. questa pratica ha tuttavia favorito il progressivo deterioramento della copertura erbacea e del suolo; infatti, gli animali al pascolo hanno provocato la diffusione di una specie vegetale resistente e invasiva, la ferula (f. communis) perché tossica e quindi fig. 10 la continuità della pendenza, lungo il versante argilloso che degrada verso l’alveo del f. so di s. savino, è interrotta dalla presenza dei blocchi calcarei, crollati in epoche diverse e poi lentamente trascinati a valle da fenomeni gravitativi che ne permettono il movimento continuo. the clayey slope continuity toward the s. savino stream is interrupted by limestone blocks, fallen down in different periods. these blocks moved slowly down by continuous landslides phenomena. fig. 11 la perdita di sostegno, indotta dall’erosione delle sabbie gialle sulle quali era fondata la cinta muraria di tarquinia vecchia, ne mette a rischio la stabilità in più punti. the lack of the ground support, due to erosion of the yellow sands is the main reason of the slope instability in several places of the ancient tarquinia. fig. 12 lunghe tratte della cinta muraria di tarquinia vecchia, interessate dal movimento del terreno fondale, hanno perduto la verticalità e sono prossime al ribaltamento. long sides of the ancient tarquinia surrounding wall affected by ground foundation movements, lost their vertical structure and are next to toppling. fig. 13 gli scavi e le strutture da questi messe in luce possono rappresentare una via di facile raccolta e veloce scorrimento delle acque superficiali con locali incrementi dell’erosione. the excavations and the resulting highlighted structures could represent a preferential river network that leads to some local higher rate of erosion. condizioni geomorfologiche e stabilità dell’acropoli ... 232 istintivamente immangiabile. la copertura erbacea appetibile è invece sparita completamente e, come conseguenza, anche il suolo è stato progressivamente eroso. per ampie estensioni è venuta alla luce la roccia calcarea fratturata che ha subito l’incremento dei processi corrosivi; lungo le fratture beanti, inoltre, le acque si incanalano in grande quantità andando ad alimentare il circuito sotterraneo e questo fenomeno si realizza anche lungo gli scavi che rappresentano una via preferenziale per il deflusso idrico (fig. 13). la terra, trascinata dalle acque entro le fratture, rende possibile in esse la crescita di specie arboree dotate di un apparato radicale in grado di ampliarle ulteriormente. conclusioni e possibili interventi in mancanza di rilievi topografici mirati (sezioni e piani quotati) e di dati sul comportamento geomeccanico delle argille, non è ovviamente possibile avanzare alcun tipo di progetto, sia pure di massima, utile alla salvaguardia del patrimonio archeologico di tarquinia vecchia. tuttavia, note le caratteristiche geomorfologiche dell’area e la loro evoluzione, è possibile elencare, come in fig 14, gli interventi più idonei per rallentare i processi geomorfologici in atto, mitigando il pericolo di perdita della stabilità dei manufatti d’interesse archeologico: 1. rallentare il ruscellamento disordinato e riducendo sia il dilavamento che l’infiltrazione (opere di raccolta/drenaggio delle acque meteoriche e riduzione della permeabilità superficiale del terreno, favorendo la ricostituzione del suolo e della copertura vegetale); 2. raccogliere e canalizzare le acque emergenti al piede della cornice calcarea per evitare la saturazione e la plasticizzazione delle argille azzurre; 3. edificare opere di sostegno al piede della scarpata calcarea, per contrastare e/o contenere i fenomeni di crollo; nella fascia di terreni prossima al piede dei calcari, le pratiche agricole, e l’aratura in particolare, dovrebbero essere vietate. bibliografia bonadonna f.p. (1967) studi sul pleistocene nel lazio, ii: linee di costa lungo il litorale di tarquinia (lazio settentrionale). geologica romana, vi, 121-135. bonghi j.m. (1986) -testimonianze archeologiche e ricostruzione storica, scavi sistematici nell'abitato. gruppo archeologico romano, i, 11-135, 6 tav. bellotti p., evangelista s., la monica g.b., landini b., milli s. (1993) itinerario n° 11: da roma a tarquinia . vol. 5 (lazio) guide geologiche regionali. soc. geol. it. chiocchini u. (1990) caratteri sedimentologici e stratigrafici delle calcareniti di tarquinia. boll. soc. geol. it., 12, 210-221. fazzini p., gemini r., mantovani m.p. & pellegrini m. (1972) geologia dei monti della tolfa (lazio settentrionale; prov. roma e viterbo). mem. soc. geol. it, 11, pp. 65-144. fregni p., gasperi g. & gelmini r. (1985) il messiniano tra la toscana meridionale e il lazio settentrionale. mem. soc. geol. it, 25, pp. 233-287. ms. ricevuto il 20 febbraio 2006 testo definitivo ricevuto il 31 ottobre 2006 ms. received: february 20, 2006 final text received: october 31, 2006 fig. 14 schema delle possibili opere tese a ridurre il rischio idrogeologico nell’area dell’acropoli. scheme of the hypothetical works in order to reduce the hydrogeologic risk in the acropoli area. c. cattuto et al. imp.capaccioni& caratterizzazione idrochimica di un acquifero superficiale: il caso della circolazione idrica nei corpi di frana nella dorsale carbonatica di m. pietralata – m. paganuccio (appennino marchigiano) bruno capaccioni1, olivia nesci2, enrico maria sacchi2, daniele savelli2 & francesco troiani2 1istituto di vulcanologia e geochimica, università degli studi “carlo bo”, campus scientifico, loc. crocicchia, 61029 urbino – b.capaccioni@uniurb.it 2istituto di geologia, università degli studi “carlo bo”, campus scientifico, loc. crocicchia, 61029 urbino – d.savelli@uniurb.it riassunto: capaccioni b., nesci o., sacchi e. m., savelli d. & troiani f., caratterizzazione idrochimica di un acquifero superficiale: il caso della circolazione idrica nei corpi di frana nella dorsale carbonatica di m. pietralata m. paganuccio (appennino marchigiano). (it issn 0394-3356, 2004). nella presente nota sono descritti i risultati di una ricerca sulle caratteristiche idrochimiche delle acque di sorgente emergenti dai corpi di frana che interessano i fianchi della dorsale anticlinalica di m. pietralata – m. paganuccio. il collasso gravitativo di gran parte dei fianchi della dorsale, legato principalmente all’assetto morfostrutturale e litostratigrafico dell’area, coinvolge generalmente il substrato e ha prodotto vasti e spessi accumuli di frana, variamente dislocati e disarticolati. le masse franate, avendo sviluppato una elevata permeabilità secondaria, hanno costituito acquiferi propri e sensibilmente condizionato la circolazione idrica sotterranea più superficiale. ciò ha generato numerosi punti di scaturigine distribuiti sia alla base del rilievo, ai margini dei principali corpi di frana, sia all’interno dei corpi stessi. in certi casi, invece, gli accumuli di frana probabilmente ricoprono sorgenti legate a circuiti più profondi, all’interno delle rocce del substrato. i risultati delle analisi chimiche effettuate sulle acque di sorgente nelle campagne di monitoraggio del 1984 e del 2004, oltre a caratterizzare facies idrochimiche sub-superficiali direttamente legate ai corpi di frana, sottolineano proprio una loro probabile miscelazione con acque di provenienza più profonda.. abstract: capaccioni b., nesci o., sacchi e. m., savelli d. & troiani f., the hydrochemical feature of surficial groundwaters: the groundwaters from landslide deposits of the carbonatic ride of mts. pietralata-paganuccio (marche appennines. (it issn 0394-3356, 2004). geological-geomorphological and hydrochemical studies have been carried out throughout the anticline ridge of pietralata-paganuccio mts. (northern umbria-marche apennines, central italy) in order to find a possible correlation between the large landslides almost affecting the entire mountain flanks and spring-water characteristics. the study area embraces the northernmost sector of a much longer calcareous anticline ridge extending all along the marche region. the furlo gorge, a narrow transverse canyon deeply cut by the candigliano river (metauro river basin), breaches the anticline ridge separating the two mountains from each other. this sector of the ridge, although rather simple as for its morphostructure, is indeed one of the most important examples of such landforms so characteristic of the umbria-marche apennines. pietralata and paganuccio mts. consist of the mostly calcareous and marly-calcareous mesocenozoic units of the umbria-marche succession. the jurassic-cretaceous terrains, ranging from the calcare massiccio fm. and the scaglia bianca fm., crop out in the furlo gorge area only, deeply cut in its turn at the core of the anticline. the flanks and the crest of the anticline ridge, on the contrary, are made up of createceous-oligocene terrains, namely scaglia rossa-scaglia cinerea and bisciaro fms. pietralata and paganuccio mts. are an explicatory example of an exhumed anticline, where the geological structure is distinctly replicated by the relief topography. indeed, the ridge morphology almost perfectly displays both the rounded geometry of the anticline and its northwestern and southeastern plunge-out areas. furthermore, characteristic flat top-surfaces markedly reflect the sub-horizontal/gently-dipping bedding of the hinge zone, while the mountain sides slope at angles approximating the downslope-dipping layering values. although the peculiar morphostructural arrangement of the ridge has been shaped by different processes, the role of large, deep-seated mass movements is once more today among the most effective ones. landslides, affecting both sides of the ridge for the most part, find their key predisposing factors in the dip-slope layering attitude on the two sides of the anticline ridge, as well as in the occurrence of weak marly horizons (e.g. marne a fucoidi fm., marly members of scaglia rossa fm., etc.),embedded among calcareous units in different stratigraphic positions. the occurrence of an intense local rock-fracturing is an effective additional predisposing factor. as a result, the most part of the anticline ridge flanks have been extensively denudated by more or less shallow landsliding, able to highlight both lithologic contrasts of the jurassic-miocene “multilayer” and structural features, such as fault-zones and bended bedding surfaces. the gravitational sagging and collapse of the anticline flanks encompass several, different field evidence. as a rule, the landslide head areas display tension cracks and more or less distinct trenches, scarps and counterslopes; the slid mass becoming more and more disrupted and chaotic downslope, where an over-100m thickness is often reached and stressed by deep gully dissection of the landslide mass. indeed, the substantial permeability acquired by progressive fracturing of the sliding rock bodies allows for a great number of frequently perennial aquifers and springs to occur within the slid-bodies and/or at the toe of the major landslides. on the contrary, in some places, the landslide materials have probably blanketed some springs related to relatively deep bedrock aquifers. hydrochemical data show that the characteristics of the majority of the analysed waters set in the field of ca2+ hco3 compositions, with two different trends, namely “a”, trending towards na+ clcompositions, and “b”, trending towards ca2+ so4 2compositions. a possible reason of these two trends is the mixing of superficial water circulating inside the landslide masses with waters flowing out from deeper bedrock-aquifers. water samples from the pietralata mt. area, according to the most part of waters from carbonatic rocks of the marche region, display contents in ca2+, mg2+ and hco3 which are mostly due to magnesian-calcite solution or, alternatively, to a mixing of calcite and dolomite (this latter, especially for waters from relatively deep aquifers). as regards water saturation in calcite at different pco2 conditions, the analysed samples display a range of values approximating those typical for soils (0.15 bar). being such values much higher than those already reported for carbonate aquifers of nerone mt. (0.0003 – 0.003 bar), a near-surface water circulation can be alleged. in this respect, a similar assumption can be drawn from both the relatively low discharges of the studied springs, and from the recurring traces of no3 concentration. as regards this latter, in particular, its relatively high concentration in both 1984 and 2004 samplings is likely to be related to both biologic activity and humification (nitrification) on the surface of the slid-masses, although a less important amount of no3 from fertilizers cannot be ruled out. moreover, a low ca2+ so4 2composition of the samples at issue can be related to the mixing of relatively deep waters from bedrock aquifers whose springs are blanketed by thick landslide accumulations. finally, the observed trend “a”, towards na+ clcompositions, can be ascribed to cyclic salts coming from near marine areas. parole chiave: corpi di frana, idrochimica, dorsali carbonatiche, monti paganuccio e pietralata, italia. keywords: landslide bodies, hydrochemistry, carbonate ridges, paganuccio-pietralata mts., central italy. il quaternario italian journal of quaternary sciences 17(2/2), 2004, 585-595 586 b. capaccioni et al. 1. introduzione la dorsale carbonatica del m. paganuccio-m. pietralata (fig. 1) presenta numerose sorgenti, distribuite sia sulle aree più elevate che lungo le sue fasce perimetrali e alla base dei versanti. l’ubicazione delle principali sorgenti perenni, monitorate nel 2004, è riportata nelle figure 2 e 3. i punti di scaturigine di alcune di esse si trovano su roccia in posto (sorgenti n. 1, 4, 5 8 in figura 3), soprattutto in prossimità e/o in corrispondenza di apprezzabili contrasti litologici o di dislocazioni tettoniche. la maggior parte delle sorgenti è invece ubicata sul margine di potenti coltri detritiche e/o su rocce interessate da reti di fratture secondarie più o meno persistenti ed evidenti in superficie. il numero relativamente elevato di sorgenti associate a masse detritiche e/o rocce fratturate si collega direttamente al collasso gravitativo quasi generalizzato dei fianchi della dorsale, determinato dall’assetto litostratigrafico e morfo-strutturale della stessa (cf. burattini et al., 1989; diligenti et al., 2004). i movimenti di versante, vasti e spesso profondi, hanno infatti dato origine sia a un’intensa fratturazione secondaria delle rocce, sia alla formazione di potenti coltri costituite da materiale roccioso variamente mobilizzato e disgregato (nesci & savelli, 1986). proprio questa situazione ha determinato lo sviluppo di un certo numero di acquiferi relativamente superficiali localizzati all’interno o al margine dei corpi interessati da collasso gravitativo e sostenuti da orizzonti acquicludi e acquitardi in corrispondenza dei livelli di scivolamento. oggetto della presente nota è fornire alcune indicazioni di carattere geologico-geomorfologico utili all’inquadramento e caratterizzazione delle emergenze idriche e allo stesso tempo di descrivere tali emergenze da un punto di vista idrochimico, nonché di individuare eventuali possibili interazioni tra gli acquiferi superficiali e quelli più profondi. 2. assetto geologico e geomorfologico i monti pietralata e paganuccio (qui detti monti del furlo, seguendo una denominazione locale), separati fra loro dalla profonda gola diaclinale del furlo (figg. 1-3), costituiscono un esempio particolarmente esplicativo, sebbene piuttosto semplice dal punto di vista morfostrutturale, delle dorsali anticlinaliche carbonatiche che caratterizzano l’appennino umbromarchigiano (cf. diligenti et al., 2004). i due rilievi anzidetti costituiscono la terminazione settentrionale di una più ampia morfostruttura ad assetto anticlinorico (dorsale marchigiana di centamore et al., 1972) che partendo dal massiccio dei monti sibillini attraversa quasi l’intera regione marchigiana, estendendosi verso nw fino al bacino del fiume metauro e andando così a costituire uno degli elementi morfostrutturali più rilevanti di questo settore dell’appennino (bisci & dramis, 1991 cum bibl.). i rilievi del monte paganuccio (a se, 976 m) e del monte pietralata (a nw, 888 m), in particolare, corrispondono a una accentuata culminazione della dorsale che, in direzione assiale, fig. 1 ubicazione dell’area e assetto geologico regionale. 1 = termini calcarei e calcareo-marnosi meso-cenozoici delle dorsali carbonatiche; 2 = termini marnoso-calcarei, evaporitici e silicoclastici cenozoici; 3 = coltre della val marecchia; 4 = termini terrigeni pliopleistocenici; 5 = depositi alluvionali e costieri del pleistocene medio-olocene; m = dorsale marchigiana; um = dorsale umbromarchigiana; a = dorsale minore di acqualagna; c = dorsale minore dei monti della cesana. location of the study area and regional geologic setting. 1 = meso-cenozoic calcareous and marly-calcareous formations of the carbonatic ridges; 2 = cenozoic marly-calcareous, evaporitic and siliciclastic formations; 3 = val marecchia allochthon; 4 = plio-pleistocene terrigenous formations; 5 = middle pleistocene-holocene fluvial and coastal deposits; m = marche ridge; um = umbria-marche ridge; a = acqualagna minor ridge; c = monti della cesana minor ridge. digrada rapidamente sia verso nw (terminando nella valle del metauro all’altezza di fermignano, fig. 1), sia verso se (descrivendo l’ampia depressione topografica attraversata dalla valle del fiume cesano, fig. 1). verso nord-est la dorsale si collega con una stretta depressione sinclinalica (sinclinale del metauro) che la separa da una dorsale anticlinalica minore più esterna (monti della cesana), mentre verso le aree interne (sud-ovest), si collega all’ampio sinclinorio corrispondente col cosiddetto bacino marchigiano interno (centamore et al., 1972). dal punto di vista strutturale la dorsale coincide con una piega ne-vergente, caratterizzata da una geometria a scatola, con cerniera piatta e fianchi ripidi (deiana & pialli, 1994 cum bibl.) e asse localmente con direzione n120°. l’immersione della linea di cerniera, rispettivamente verso nw a monte pietralata e verso se a monte paganuccio, evidenzia come la culminazione topografica della dorsale, espressa dai monti del furlo, corrisponda a una culminazione strutturale dell’anticlinale. inoltre, singolarmente, è proprio in corrispondenza della culminazione stessa (figg. 2 e 3) che il fiume candigliano oltrepassa la dorsale attraverso il profondo canyon della gola del furlo (cf. mayer et al., 2003). a differenza di quanto si osserva in molte anticli587caratterizzazione idrochimica di un acquifero ... nali umbro-marchigiane, il fianco esterno della struttura non presenta superfici di sovrascorrimento riconoscibili in affioramento. il versante che collega la sommità della dorsale con il fondovalle (qui coincidente con la zona assiale della sinclinale del metauro) è invece interessato da un esteso retroscorrimento (capuano & giampieri, 1989). la strutturazione della dorsale è iniziata nel tortoniano, a seguito di una tettonica a pieghe e thrust con vergenza orientale (centamore et al., 2002 cum bibl.). tra la fine del pleistocene inferiore e il pleistocene medio, l’attività plicativa e dei thrust si è esaurita, lasciando posto a un sollevamento generalizzato accompagnato da movimenti differenziali e da una deformazione post-thrusting cui corrispondono faglie associabili a una estensione orientata in senso wswene (di bucci et al., 2003). i terreni che costituiscono i monti del furlo appartengono (cf. cecca et al., 2001) ai termini meso-cenozoici della successione umbro-marchigiana (fig. 3) compresi fra le formazioni del calcare massiccio (lias inferiore) e del bisciaro (miocene inferiore). il nucleo della dorsale anticlinalica è costituito dal calcare massiccio (fig. 3), la formazione più antica affiorante nell’area, ben visibile sia sulle pareti della gola del furlo (con spessori superiori a 500 m) che nell’adiacente fig. 2 dtm dei fianchi sud-occidentale (a) e nord-orientale (b) dei monti del furlo e ubicazione delle sorgenti perenni monitorate nel 2004. si notino alla base dei versanti, in a, la serie dei flatirons e, in b, la fitta rete di solchi di erosione. per una discussione più approfondita si veda il testo. esagerazione verticale 1:2. dtm of south-western (a) and north-eastern (b) flanks of monti del furlo and location of the perennial springs monitored in 2004. please note at the ridge foot-slope, in a the series of flatirons, and in b the closely-spaced parallel gullies. see the text for a more detaild discussion. vertical exaggeration 1:2. 588 forra del buzzo e rappresentata da calcari dolomitici in strati mal definiti, da spessi a molto spessi, deposti in ambiente di piattaforma carbonatica. i termini del giurassico inferiore e medio compresi fra il calcare massiccio e la base della maiolica sono rappresentati da litofacies prevalentemente carbonatiche, spesso nodulari, con rapporti geometrici complessi e notevole variabilità laterale (cf. cecca et al., 2001 cum bibl.) che esprimono un ambiente di deposizione di scarpata/alto strutturale. la maiolica (giurassico superiore-cretacico inferiore), di spessore variabile da poco più di 100 m a circa 300 m, costituita da calcari micritici bianchi ben stratificati con selce grigio-nerastra in liste e noduli, affiora tutt’attorno al nucleo dell’anticlinale inciso dalla gola del furlo e dalla forra de il buzzo (fig. 3). le sovrastanti marne a fucoidi (cretacico medio, spessore di circa 80 m), rappresentate da argille e marne varicolori passanti verso l’alto a calcari marnosi da biancoverdastri a bianco rosati con liste e noduli di selce varicolore, separano la maiolica dai termini del gruppo delle b. capaccioni et al. fig. 3 schema geologico-geomorfologico dei monti del furlo e ubicazione delle sorgenti perenni monitorate nel 2004. 1 = calcare massiccio-corniola (triassico superiore-giurassico inferiore); 2 = rosso ammonitico (giurassico inferiore); 3 = bugarone-maiolica (giurassico medio-cretaceo medio); 4 = marne a fucoidi (cretaceo medio); 5 = scaglia rossa-scaglia cinerea (cretaceo superioreoligocene); 6 = bisciaro (miocene inferiore); 7 = corpo di frana (pleistocene superiore-olocene); 8 = detrito caotico di versante (pleistocene superioreolocene); 9 = alluvioni in parte terrazzate (olocene); 10 = alluvioni terrazzate (pleistocene superiore); 11 = alluvioni terrazzate (pleistocene medio-finale); 12 = alluvioni terrazzate (pleistocene medio). geologic-geomorphologic sketch map of monti del furlo and location of the spring monitored in 2004. 1 = calcare massiccio-corniola fms. (upper triassic-lower jurassic); 2 = rosso ammonitico fm. (lower jurassic); 3 = bugarone-maiolica fms. (middle jurassic-middle cretaceous); 4 = marne a fucoidi fm. (middle cretaceous); 5=scaglia rossa-scaglia cinerea fms. (upper cretaceous-oligocene); 6 = bisciaro fm. (lower miocene); 7 = landslide (upper pleistocene-holocene); 8 = slope-waste deposits (upper pleistocene-holocene); 9 = modern flood plain deposits and holocene alluvium (holocene); 10 = terrace alluvium (upper pleistocene); 11 = terrace alluvium (late-middle pleistocene); 12 = terrace alluvium (middle pleistocene). 589 scaglie (formazioni della scaglia bianca, scaglia rossa, scaglia variegata e scaglia cinerea). questi ultimi, riferibili all’intervallo cretacico superiore-oligocene, con uno spessore complessivo di quasi 600 m, ricoprono gli interi fianchi della dorsale anticlinalica (fig. 3), e sono caratterizzate da litofacies calceree e calcareo-marnose a luoghi contenenti liste e noduli di selce da nerastra a rosata. data la posizione di questi terreni sui fianchi della dorsale, la differente competenza litologica dei diversi intervalli e, soprattutto, la presenza di spessi orizzonti marnosi intercalati a calcari/calcari marnosi ben stratificati, costituiscono elementi di importanza fondamentale nel predisporre la struttura ai collassi gravitativi oggetto della presente nota. in tale ambito, assumono un significato molto rilevante i caratteri litostratigrafici della scaglia rossa che, in accordo con la suddivisione di wezel (1979) risulta localmente costituita (dal basso verso l’alto) da calcari rosati con selce (lower cherty mbr.), calcari rossi senza selce (calcarenite mbr.), un orizzonte marnoso (marly mbr.), calcari marnosi rossi senza selce (marls and limestones mbr.), calcari rosati con selce (upper cherty mbr.). in particolare, alcuni livelli marnosi paleocenici, con spessori compresi fra circa 3 e 10 m, intercalati nella porzione inferiore dei calcari marnosi rossi senza selce, giocano un ruolo determinante nella predisposizione al dissesto dei due fianchi della dorsale anticlinalica. altrettanto importanti sono i numerosi e raffittiti interstrati marnosi di spessore decimetrico che caratterizzano sia i calcari rosati con selce della parte superiore della formazione che la base della sovrastante scaglia variegata. la formazione del bisciaro (miocene inferiore, circa 70 m di spessore), costituita da calcari siliceomarnosi e marne di colore grigio-verdastro in strati variabili da pochi centimetri a 10∏20 cm, chiude la locale successione (fig. 3) e va a costituire l’ossatura di una serie di rilievi omoclinali (flatirons) distribuiti lungo l’intero fianco orientale dell’anticlinale (fig. 2). l’assetto geomorfologico dell’area al di fuori della gola del furlo ricalca piuttosto fedelmente la struttura anticlinalica del substrato. i due settori principali della dorsale, rappresentati da monte pietralata e monte paganuccio (figg. 2 e 3), evidenziano efficacemente sia la geometria arrotondata della struttura anticlinalica che le immersioni assiali verso l’area periclinalica (a nordovest) e verso una accentuata depressione assiale (a sud-est). i fianchi della dorsale sono inoltre bordati da dorsali omoclinali segmentate in caratteristici flatirons (fig. 2). inoltre, in corrispondenza della stratificazione sub-orizzontale o debolmente inclinata della zona di cerniera si sviluppano caratteristici piani sommitali, mentre i versanti, a franapoggio, presentano angoli di pendio che approssimano l’inclinazione degli strati o sono leggermente maggiori. la morfostruttura ha acquisito la sua attuale conformazione grazie all’intervento di processi diversi, dalla degradazione ai movimenti di massa, al dilavamento, a fenomeni crionivali. a prescindere dal tipo di processo, l’erosione selettiva ha quasi ovunque accentuato sia i caratteristici contrasti litologici nei termini giurassico-miocenici della locale successione, sia le geometrie delle superfici di strato e le zone di faglia. inoltre, dato che degradazione ed erosione sono stati molto più efficaci nel corso degli episodi freddi pleistocenici, molte delle forme strutturali che oggi caratterizzano i monti del furlo, sono quasi completamente ereditate da fasi morfogenetiche fredde del passato (nesci & savelli 1986; diligenti et al., 2004). fra i meccanismi morfoevolutivi più recenti un’importanza fondamentale è rivestita da grandi frane per scivolamento che si osservano lungo i versanti a franapoggio che caratterizzano i fianchi della dorsale carbonatica (fig. 3). queste, come poco sopra accennato, trovano il fattore predisponente sia nella condizione giaciturale degli strati sui fianchi della struttura, sia nella presenza a vari livelli di intervalli litologicamente deboli, come le marne a fucoidi o gli intervalli marnosi all’interno della scaglia rossa poc’anzi menzionati. altro importante fattore che predispone al collasso di interi versanti e al progressivo “sgusciamento” della struttura, è la presenza di fitte reti di fratture che interessano le rocce del substrato con direzioni sia sub-parallele che trasversali all’asse dell’anticlinale. il collasso gravitativo dei versanti si manifesta in svariati modi, dalle semplici fratture di tensione e piccole trincee che, specie nelle zone sommitali, esprimono un blando scorrimento superficiale degli strati, ai potenti ammassi di detrito caotico che ricoprono spesso interi versanti. per tutta l’estensione dei versanti (cf. figg. 2, 4, 5) si possono osservare vistose gradonatore e terrazzamenti a sviluppo ortogonale alla linea di massima pendenza, nicchie di distacco, pacchi di strati ruotati o completamente scompaginati. la maggior parte dei fenomeni gravitativi dell’area coinvolge il substrato roccioso, costituito soprattutto dalle formazioni appartenenti al gruppo delle scaglie. molte delle maggiori frane (come p. es. quella di ca i fabbri, figg. 2 e 3, cf. diligenti et al., 2004) hanno origine dai piani sommitali, in corrispondenza della cresta della struttura anticlinalica (figg. 2 e 3). in alcuni casi (p. es. ca i fabbri) sono presenti accentuate scarpate di frana, mentre in altri casi il movimento si sviluppa con gradualità, senza che la zona di coronamento mostri una vera e propria scarpata principale. una caratteristica comune a tutti i maggiori corpi di frana è una evoluzione retrogressiva, con presenza di masse rocciose roto-traslate poco scompaginate e morfologie di frana molto fresche nella parte alta e disarticolazione dei materiali via via crescente verso il piede dei versanti. nella parte medio-inferiore dei versanti, in particolare, gli accumuli sono rappresentati da potenti ammassi detritici (fino a oltre 100 m di spessore) ad assetto caotico (cf. fig. 9 in nesci & savelli, 1986). la scarsa coesione di queste masse, inoltre, fa sì che su di esse si imposti tutta una serie di movimenti di massa superficiali e che esse vengano attivamente smantellate dalle acque superficiali, con produzione di profondi solchi d’erosione cui si collegano coni detritici e detritico-alluvionali (figg. 2-5). i principali accumuli di frana e/o i corpi rocciosi traslati e disarticolati anche in modo molto blando, sviluppando una significativa permeabilità secondaria, sono associati ad acquiferi e sorgenti perenni (figg. 2 e 3) o a deflusso saltuario emergenti sia alla base del rilievo che a quote più elevate. in certi casi, gli accumuli di frana sembrano costituire “mezzi filtranti” in grado di rimescolare le acque “di frana” superficiali con acque di provenienza relativamente più profonda caratterizzazione idrochimica di un acquifero ... 590 b. capaccioni et al. fig. 4 veduta del versante nord-orientale di m. paganuccio. in evidenza la morfologia di frana sull’intero versante e le profonde incisioni al piede di grandi accumuli di frana ormai stabilizzati. the north-eastern flank of monte paganuccio. please note the landslide morphology on the whole hillslope and, in the lower sector of the slope, some deep gullies affecting inactive chaotic landslide deposits. fig 5 morfologia di frana sul versante sud-occidentale di m. paganuccio. si notino al piede del versante le forme calanchive impostate su materiali di frana caoticizzati. landslide morphology on the south-western flank of monte paganuccio. accelerate erosion emphasized by deep gullying is actively removing the down-slope part of the landslide deposits. 3. caratterizzazione idrochimica delle acque sorgive i principali accumuli di frana e/o i corpi rocciosi traslati e disarticolati anche in modo molto blando, sviluppando una significativa permeabilità secondaria, sono sede di acquiferi e sorgenti perenni o a deflusso saltuario emergenti in generale alla base del rilievo. dal diagramma quadrato di langelier-ludwig (1942) (fig. 6) si evidenzia come la totalità delle acque campionate si colloca nel campo delle bicarbonato calciche. dalle analisi del 1984 (noschese, 1984) risultavano due tendenze distinte, una verso composizioni clorurato sodiche (trend “a”), con un campione (quello a più alta salinità) con caratterizzazione clorurato sodica, e una verso composizioni solfato calciche (trend “b”). i campioni prelevati nel 2004, ad eccezione di uno che segue il trend “a”, si concentrano all’origine dei due trend nel campo caratteristico delle acque bicarbonato calciche. il diagramma di saturazione della calcite (fig. 7) evidenzia una distribuzione dei campioni tra la curva di saturazione della calcite alla pressione di co2 dei gas del suolo pari a 0.15 bar e quella dell’aria pari a 0.003 bar. la distribuzione dei campioni mostra una netta dipendenza dalla dissoluzione di calciti magnesiache, mentre si nota come i contenuti di hco3 del 2004 rispetto a quelli del 1984 abbiano subito uno slittamento verso valori più prossimi alla curva di saturazione per una pco2 tipica dei gas del suolo. a titolo di comparazione dei dati sono stati inserite nel grafico le aree composizionali tipiche degli acquiferi profondi del massiccio carbonatico di monte nerone (capaccioni et al, 2001) e le quelle di acquiferi superficiali in corpi di frana nell’alta valle del torrente apsa nei pressi di urbino (sambuchi, 2004). risulta evidente come i campioni si collochino in un campo di pco2 intermedio tra quello tipico degli acquiferi in equilibrio con i valori tipici di un suolo maturo e quello caratteristico degli acquiferi profondi. il diagramma di correlazione tra sodio e cloruri 591caratterizzazione idrochimica di un acquifero ... fig. 6 diagramma classificavo di langelier-ludwig delle acque dei monti del furlo. circoletti = campioni prelevati nel 1984 sul monte pietralata. quadrati=campioni prelevati nel 2004 sul monte pietralata. triangoli=campioni prelevati nel 2004 sul monte paganuccio. langelier-ludwig’s classification diagram of the monti del furlo spring water. open circles=samples from monte pietralata, year 1984. open squares= samples from monte pietralata collected on 2004. open triangles=samples from monte paganuccio, year 2004. (fig. 8) evidenzia che le acque dei campioni prelevati tendono ad allinearsi in prossimità della retta di rapporto di equivalenza sodio/cloruri 1:1, rapporto che si ottiene quando i due ioni derivano dalla dissoluzione di cloruro di sodio. dal grafico ca2+ / so4 2(fig. 9) si nota come la distribuzione della maggior parte dei campioni prelevati nel 1984 e nel 2004 non mostrano correlazioni significative tra le due variabili, con rapporti tra i due elementi decisamente superiore all’unità, indicando quindi una netta e costante dominanza della componente calcica, mentre le acque campionate nel 1984 del trend “b” mostrano una netta correlazione positiva parallela alla retta di equivalenza calcio/solfati. in base ai dati idrochimici raccolti (tab. 1) si può affermare che le acque sotterranee pur appartenendo alla categoria delle bicarbonato calciche mostrano una tendenza verso composizioni clorurate sodiche. in considerazione dell’assenza di depositi noti di nacl nelle formazioni che costituiscono gli acquiferi, tale caratteristica potrebbe essere imputabile alla dissoluzione nelle stesse di cloruro di sodio probabilmente di origine “ciclica”, ovverosia da deposizione umida o secca di microcristalli di nacl originatesi da spray marino e trasportati in sospensione nell’entroterra. in particolare, a risentire dei sali ciclici sono per lo più le sorgenti poste alle quote più elevate. la tendenza verso composizioni solfato calciche, evidente sui campioni del 1984 (trend “b”, fig. 6), potrebbe essere messa in relazione a miscelazioni con acque di circuiti idrogeologici più profondi, la cui caratterizzazione solfato calcica potrebbe derivare da processi ossidativi su solfuri dispersi, la cui presenza è documentata sulle formazioni della scaglia bianca, marne a fucoidi e maiolica (cf. coccioni at al., 1994; 1987.) l’assenza di evidenze di processi di miscelazione nei campioni prelevati nel 2004 potrebbe derivare da un generale abbassamento dei livelli piezometrici durante l’ultimo ventennio e/o dalla localizzazione delle loro emergenze a quote superiori ai 300 m slm. i campioni dell’area in esame, come la maggior parte dei campioni di acque provenienti dagli acquiferi carbonatici della regione, mostrano contenuti in ca2 +, mg2 + e hco3 riferibili a prevalente dissoluzione di calciti magnesiache. le acque in esame mostrano valori di pressione di co2 prossimi a quelli tipici dei suoli (0.15 bar), ciò indica verosimilmente una circolazione idrica relativamente superficiale, come del resto testimoniata dai bassi valori di portata misurati. inoltre si è notato come le sorgenti alle pendici dei massicci presentino un contenuto di co2 minore rispetto le sorgenti poste alle quote più elevate. nel grafico in esame la traslazione dei campioni rispetto le due campagne di monitoraggio è dovuta verosimilmente al fatto che nel 1984 i campioni sono stati prelevati nel mese di settembre, periodo siccitoso, mentre nel 2004 i campioni prelevati nel mese di febbraio hanno risentito della miscelazione con acque di circolazione più superficiali, le quali si sono arricchite di co2 come conseguenza della circolazione negli orizzonti più superficiali del suolo. inoltre nel mese di febbraio gli apporti di acque superficiali hanno fatto si che la componente bicarbonato calcica prevalga in modo 592 b. capaccioni et al. fig. 7 diagramma di saturazione della calcite. simboli come in fig. 6. calcite saturation diagram. symbols as in fig. 6. decisivo sulle altre due. un’ulteriore conferma della superficialità degli acquiferi deriva dalle concentrazioni di nitrati, relativamente alte, riscontrate nelle campagne di monitoraggio del 1984 e 2004, la cui origine è imputabile all'attività biologica negli orizzonti superficiali humificati (nitrificazione). a tutt’oggi, i valori di tali composti sono rimasti pressoché inalterati, unica eccezione è il campione sito in località ca’bernardi (sorgente n° 10) in cui i valori si aggirano attorno ai 52 mg/l; tale anomalia potrebbe essere connessa al fatto che le acque sotterranee circolano al di sotto di aree adibite ad uso agricolo. 593caratterizzazione idrochimica di un acquifero ... fig. 8 diagramma di correlazione cl-/na+. simboli come in fig. 6. cl-/na+ correlation diagram. symbols as in fig. 6. fig. 9 diagramma di correlazione ca2+/so4 2-. la linea tratteggiata indica i campioni corrispondenti al trend “b” di fig. 1. simboli come in fig. 6. ca2+/so4 2correlation diagram. dashed line points out samples from trend “b” on fig. 1. symbols as in fig. 6. 594 b. capaccioni et al. tab.1 parametri chimici determinati. i campioni del 1984 privi di numerazione sono quelli non ricampionati e quindi non comparati con quelli del 2004. chemical parameters. the unnumbered samples, collected only in 1984, are not compared with 2004 samples. analisi chimiche dei campioni prelevati nel 1984 sorgente nitrati solfati cloruri alcalinità potassio sodio cloro magnesio n° ppm ppm ppm ppm ppm ppm ppm ppm 0,8 4,5 14 171 0,7 5,0 58 2,0 1,5 3,0 21 195 1,6 10,5 64 2,0 2,0 8,0 13 108 2,0 14,0 24 2,4 1,1 9,0 22 256 1,2 9,5 82 6,0 1,2 2,0 17 180 0,6 6,0 58 4,0 8 2,0 4,5 20 210 1,3 11,0 66 4,0 2,0 9,0 22 201 1,1 11,0 63 8,0 4,2 8,0 26 201 0,7 10,0 62 8,0 3,0 3,0 22 250 2,3 11,0 81 3,0 16,0 36,0 18 210 1,4 11,8 65 14,0 1,5 39,0 29 271 3,6 28,0 77 11,0 8,0 20,0 26 223 2,0 13,0 70 11,0 1,7 30,0 40 220 1,5 18,0 67 15,0 1,2 19,0 22 213 1,8 12,0 65 9,0 9 0,9 3,0 18 170 0,9 8,0 49 7,0 1,2 10,0 20 165 0,8 6,6 54 1,0 0,9 5,0 19 213 0,5 8,1 66 6,0 1,2 2,0 16 201 0,6 5,3 70 1,0 1,9 5,0 25 314 2,2 17,0 83 13,0 1,5 24,0 14 296 0,9 7,5 92 10,0 1,2 101,0 23 268 0,9 12,5 100 5,0 1,2 13,0 29 232 2,0 14,5 73 7,0 1,0 95,0 19 177 1,4 101,0 50 30,0 4 1,3 58,0 19 168 0,5 8,5 53 18,0 0,4 3,0 15 165 9,9 6,0 50 4,0 7 1,2 6,0 18 198 0,6 7,2 65 4,0 0,8 10,0 17 134 0,6 7,2 47 2,0 0,8 38,0 23 256 0,7 10,9 81 14,0 1,2 11,0 13 195 0,5 5,5 65 4,0 1 1,5 5,0 24 170 9,8 9,9 60 2,0 1,0 55,0 22 223 0,9 10,0 70 18,0 1,1 12,0 20 241 0,7 8,0 72 10,0 1,5 80,0 21 201 1,2 9,0 62 25,0 1,4 23,0 27 210 1,5 11,5 67 10,0 1,4 12,0 19 204 0,7 7,0 65 7,0 1,4 95,0 21 183 2,6 7,5 94 6,0 5,0 42,0 197 244 4,8 110,0 76 22,0 analisi chimiche dei campioni prelevati nel 2004 sorgente nitrati solfati cloruri alcalinità potassio sodio cloro magnesio n° ppm ppm ppm ppm ppm ppm ppm ppm 1 3,1 14,6 38,0 213,5 0.01 27,5 68,8 2,8 2 0,3 9,0 26,8 298,9 0,48 16,5 97 2,3 3 1,3 8,0 11,6 250,1 0,74 7,4 91 1,7 4 0,4 9,4 13,6 262,3 0,48 13,6 88,8 2,5 5 1,2 12,0 19,4 231,8 1,68 12,3 73 1,8 6 1,6 6,4 15,2 237,9 0,62 10,6 76,5 2 7 0,2 7,2 23,8 231,8 0.01 8,4 74 1,8 8 0,3 8,0 11,8 256,2 0,64 13,9 79 2 9 1,3 5,8 19,0 183,0 0.01 7,6 55 3 10 52 7,6 20,2 213,5 0.01 8,8 70,3 1,8 4. conclusioni sono state visionate numerose sorgenti presenti sulla dorsale carbonatica di m. pietralata-m. paganuccio, molte delle quali ubicate in corrispondenza dei principali accumuli di frana, allo scopo di fornire l’inquadramento geologico-geomorfologico delle stesse e fornire una caratterizzazione idrochimica. le principali conclusioni sono riassumibili come segue: • le frane alle quali molte sorgenti sono collegate sono dei profondi scorrimenti di carattere roto-traslativo legate sia alla giacitura a franapoggio che alla presenza di livelli litologicamente “deboli” all’interno della locale successione. le frane sono caratterizzate da settori attivi, o comunque di più recente attivazione soprattutto verso le zone di coronamento del corpo principale. verso la base i corpi di frana sono invece costituiti da potenti accumuli detritici ad assetto caotico. la maggior parte delle sorgenti è ubicata ai piedi o ai margini dei corpi di frana di cui sopra. altre sorgenti, invece, scaturiscono direttamente da rocce del substrato. • le acque medio minerali dei detriti si caratterizzano prevalentemente in bicarbonato calciche con elevati valori di pco2 all’equilibrio e significativa presenza di nitrati. i dati idrochimici del 1984 mostrano trend di miscelazioni riferibili a risalite di acque da circuiti idrogeologici più profondi, mentre la modesta tendenza verso composizioni clorurato sodiche potrebbe associarsi alle deposizioni umide da sali ciclici. bibliografia bisci c. & dramis f. (1991) la geomorfologia delle marche. in: minetti a., nanni t., perilli f., polonara l. & principi m. (eds.), l’ambiente fisico delle marche. geologia, geomorfologia, idrogeologia. regione marche, giunta regionale, assessorato urbanistica-ambiente, pp. 81-113. burattini f., nesci o. & savelli d. (1989) late quaternary slope movements in the north marche apennines. examples from the lower candigliano and middle metauro river basins. acta naturalia de "l'ateneo parmense", 25 (1/4), pp. 61-70. capaccioni b., didero m., paletta c., salvatori p. (2001) hydrogeochemistry of groundwaters from carbonate formation with basal gypsiferous layers: an example from the mt catria-mt nerone ridge (northern appennines, italy). j. hydrol., 253, pp. 14-26. capuano n. & giampieri a. (1989) appennino marchigiano settentrionale: il retroscorrimento dei monti della cesana. boll. soc. geol. it., 108, pp. 59-68. cecca f., catenacci v., conte g., cresta s., d'andrea m., graziano r., menichetti m., molinari v., pampaloni m. l., pantaloni m., pichezzi r. m., rossi m., (2001) risultati preliminari del rilevamento nel settore sud-occidentale del foglio 280 fossombrone della carta geologica d'italia. boll. serv. geol. d’it., 115 (1996), pp 3-70. centamore e., jacobacci a. & martelli g., (1972) modello strutturale umbro-marchigiano. correlazioni possibili con le regioni adiacenti. boll. serv. geol. d’italia, 93, pp. 155-185. centamore e., fumanti f. & nisio s. (2002) the central-northern appennines geological evolution from triassic to neogene time. boll. soc. geol. it., vol. spec. 1, pp. 181-197. coccioni r., moretti e., nesci o., savelli d., tramontana m., veneri f., wezel f. c., con contributo di cecca f., cresta s., passeri l. (1994) assetto stratigrafico e strutturale della successione umbro-marchigiana-romagnola . guide geologiche regionali, 7, pp. 103-118. coccioni r., nesci o., tramontana m., wezel f. c., moretti e. (1987) descrizione di un livello guida “radiolaritico-bituminoso-ittiolitico” alla base delle marne a fucoidi nell’appennino umbro marchigiano. boll. soc. geol. it., 106, pp. 183192. deiana g. & pialli g. (1994) le province strutturali dell’appennino umbro-marchigiano. mem. soc. geol. it., 48, pp. 473-484. di bucci d., mazzoli s., nesci o., savelli d., tramontana m., de donatis m. & borraccini f. (2003) active deformation in the frontal part of the northern apennines: insights from the lower metauro river basin area (northern marche, italy) and adjacent adriatic off-shore. j. geodyn., 36, pp. 213-238. diligenti a., nesci o. & savelli d. (2004) geomorphosites in the landscape of monti del furlo (northern marche apennines). il quaternario, it. journ. quat. sc., in stampa. langelier w.f., ludwig h.f. (1942) graphical method for indicatine the mineral character of natural waters. j. am. waterworkss assoc., 34, pp. 335352 mayer l., menichetti m., nesci o. & savelli d. (2003) morphotectonic approach to the drainage analysis in the north marche region, central italy. quat. internat., 101-102, pp. 157-167. nesci o. & savelli d. (1986) cicli continentali tardoquaternari lungo i tratti vallivi mediani delle marche settentrionali. geogr. fis. dinam. quat., 9, pp. 192-211. noschese t. (1984) gli acquiferi della serie marchigiana nella zona dei m.ti delle cesane-pietralata. studio delle sorgenti e delle caratteristiche chimico-fisiche delle acque. tesi di laurea inedita, università degli studi di urbino, 168 pp. sambuchi p. (2004) studio idrogeochimico delle acque sotterranee nell’area franosa dell’alta valle dell’apsa (urbino). tesi di laurea inedita, università degli studi di urbino, 137 pp. wezel f. c. (1979) the scaglia rossa formation of central italy: results and problems emerging from a regional study. acta naturalia de "l'ateneo parmense", 15 (4), pp. 243-259. 595caratterizzazione idrochimica di un acquifero ... ms. ricevuto il 26 aprile 2004 testo definitivo ricevuto il 22 dicembre 2004 ms. received: april 26, 2004 final text received: december 22, 2004 imp.bertacchini in search of “underground urban geosites”. the city of modena “upside-down” milena bertacchini department of earth sciences, university of modena and reggio emilia (italy), l.go s. eufemia, 19, 41100 modena (italy); email: bertacchini.milena@unimore.it abstract: m. bertacchini, in search of “underground urban geosites”. the city of modena “upside-down” . (it issn 0394-3356, 2005). a rich cultural heritage is hidden in the subsoil of many italian cities. this underground heritage could tell the story and the evolution of the urban environment through the traces of natural and anthropogenetic components which shaped it in space and time and are now interwoven in the physical landscape that surrounds it. underground urban geosites are the historical and territorial memory of this evolution since they are the buried traces of urban environment components. the aim of the “sottosopra” (upside-down) project is to appraise the cultural heritage buried beneath the city of modena. there is a network of cultural itineraries following the underground town’s canals, inviting visitors to discover and enjoy all the underground urban geosites which have stratified in the subsoil of modena during nearly two thousand years of history. abstract: m. bertacchini, alla ricerca di “geositi sotterranei urbani”. la città di modena “sottosopra” . (it issn 0394-3356, 2005). un ricco patrimonio culturale è nascosto nel sottosuolo di molte città italiane. questo patrimonio sotterraneo è in grado di raccontare la storia e l’evoluzione del paesaggio urbano attraverso le tracce delle componenti naturali e antropiche che lo hanno plasmato nello spazio e nel tempo e che ora sono intessute nel paesaggio fisico che le circonda. i geositi sotterranei urbani rappresentano la memoria storica e territoriale di questa evoluzione, in quanto tracce sepolte delle componenti il paesaggio urbano. il progetto “sottosopra” intende valorizzare il patrimonio culturale sepolto sotto la città di modena grazie ad una rete di itinerari culturali che virtualmente seguono i canali sotterranei cittadini e invitano i visitatori alla conoscenza e alla fruizione di tutti quei geositi sotterranei urbani che si sono andati stratificando nel sottosuolo modenese nel corso di quasi duemila anni di storia. keywords: cultural landscape, natural components, anthropogenetic components, underground urban geosites, appraisal, fruition. parole chiave: paesaggio culturale, componenti naturali, componenti antropiche, geositi sotterranei urbani, valorizzazione, fruizione. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 163-166 1. foreword the italian landscape – one of the most important components of national cultural heritage (panizza & piacente, 2003) – is an amazing assemblage of nature and history, formed by both natural and human elements which intertwine, condition each other and eventually settle by interacting with the pre-existing environment, albeit in diverse ways and with varying intensity. historical phenomena and human vicissitudes tend to shape the landscape at ground level, whereas natural components – particularly geological components – can affect its evolution through various and sometimes remarkable processes, even involving large rock masses at considerable depths. the memory of past geological events which influenced the landscape’s evolution is preserved in the form of either visible traces above the earth’s surface or as hidden remains buried in the subsoil. therefore, geosites represent the territorial memory of these geological processes. among the various types of geosites found above or below sea level, those located in the subsoil include both geological, geomorphological, pedological etc. elements which are at present below the line of the horizon and many underground cavities which are the object of speleological exploration and research. 2. geosites in the urban context numerous italian, european and non-european cities preserve a rich hidden world in their subsoil; an underground world comprising “unusual, buried environments constructed by man through the centuries” (ardito, 2003) interwoven with the physical landscape that surrounds them. houses, aqueducts, bridges, river quays, streets, necropoles, baths, mosaics, old pavements etc., they all are real buried monuments witnessing the history, life and culture in general of old towns (bertacchini et al., 2001; 2002). all these elements combine and merge with the natural elements of the underground landscape they belong to. together with abandoned river courses, paleosoils, sedimentary sequences etc., they make up considerable “geo-archaeological” complexes, since they are the embodiment of geological, archaeological, historical, artistic and socioeconomic information. the strong and ever-growing public interest in the rediscovery of scientific, historical, tourist and cultural aspects that characterise many italian urban centres, has recently aroused also the interest of the massmedia (fig. 1). the term “urban speleology” has now become commonplace, indicating the discipline which studies caves, tunnels, narrow passages and underground shafts buried under the towns. in order to main164 m. bertacchini tain a connection with the terminology already in use and by analogy with the definition of underground geosites, the natural and anthropogenetic components of the urban landscape which are hidden in the subsoil will be defined as “underground urban geosites”. 3. the “sottosopra” project the city of modena is built on top of the remains of “mutina”, a roman colony whose urban development was strongly influenced and conditioned by the morphological evolution of water courses which in ancient times flowed near or even through it (bertacchini, 2003a). geosites are the testimony of this evolution. in order to promote awareness and information regarding the cultural heritage of the city of modena and, in particular, of its buried heritage, the “sottosopra” (upside-down) project has been planned and implemented. this is a virtual cultural pathway which was presented in modena at “the invisible town” congress, during the international day for the environment (bertacchini, 2003b). this project is now fig. 1 – excerpt from an article published on 30th may 2003 in “il venerdì”, supplement of the italian paper “la repubblica”, concerning a new form of urban tourism: “underground tourism”. stralcio di un articolo comparso il 30 maggio 2003 nell’inserto “il venerdì” del quotidiano “la repubblica”, relativo ad una nuova forma di turismo urbano: il “turismo underground”. fig. 2 – “sottosopra” is a virtual cultural pathway composed of a series of interlinked itineraries that wind through the city of modena, following the courses of underground canals. in this initial phase of the project, four itineraries coinciding with the city’s main canals have been identified: 1. naviglio; 2. canal grande; 3. canal chiaro; 4. modenella. the figure shows the areas considered by each itinerary (modified after bertacchini, 2003). “sottosopra” è un percorso culturale e virtuale composto di una serie di itinerari tra loro dialoganti, che si snodano all’interno della città di modena seguendo la traccia dei canali sotterranei. in questa fase iniziale del progetto, sono stati individuati quattro itinerari coincidenti con i principali canali della città: 1. naviglio; 2. canal grande; 3. canal chiaro; 4. modenella. in figura sono visualizzate le aree considerate da ciascun itinerario (modif. da bertacchini, 2003). taking shape, thanks to the collaboration between the department of earth sciences of modena and reggio emilia university and the environmental office of the municipality of modena (bertacchini et al., 2003). it is particularly suitable for spreading basic information about the city’s physical territory and its historical, architectural, artistic, etc. components by means of their appraisal and more immediate fruition. “sottosopra” reconstructs the story that the underground urban landscape can tell us by means of the natural and anthropogenetic remains which have shaped it in time and space (piacente, 1999). in particular, “sottosopra” underlines the presence and evolution of a dense network of natural water courses, springs and artificial canals which have always characterised the territory of modena. these waterways have always controlled and sometimes constrained the development of this city, leaving traces in the urban geosites hidden in the subsoil. for about two thousand years, the action of these waterways was so intense as to cause the accumulation of thick sedimentary sequences, which contributed to hiding and obliterating the remains of roman mutina and the subsequent early medieval and late medieval town, right up to relatively recent times. confirmation of this can be found in lugli et al. (2002) which records that paleosoil from the roman era is found at depths of 2.5 to 11 m below the present ground level in the historical town-centre of modena. in order to learn more about the history of the city of modena and its territory, visitors are invited to follow the path of its underground waterways, discovering and observing selected urban geosites, most of which have contributed to modifying the urban landscape over the years. this is the case of old pavements, streets, houses, mosaics, river quays and city gates, as well as sedimentary sequences rich in remains of daily life, witnessing past environmental conditions and paleosoils with plant remains which point to climatic conditions different from the present ones. from a practical viewpoint, the territory of modena has been subdivided into a series of itineraries (fig. 2) connected to each other. they wind through the underground courses of the main canals that still flow beneath the city centre today: the naviglio (itinerary 1), the canal grande or canale di san pietro (itinerary 2), the canal chiaro (itinerary 3) and the modenella (itinerary 4) (bertacchini et al., 2003). a series of sensitive elements, graphically differentiated according to the types of urban geosites identified (fig. 3), marks each urban asset found along each itinerary and interactively directs users to specific, detailed descriptions (fig. 4a, b): old pictures, recent photographs, films, reproductions of works of art and archaeological finds related to a specific geosite and/or to other components of the urban landscape. 165in search of “underground ...” fig. 3 – legend of some sensitive multimedia connection elements between the different forms of detailed description contained in the “sottosopra” project. legenda di alcuni elementi sensibili di collegamento multimediale tra le diverse forme di approfondimento contenute in “sottosopra”. fig. 4 – two examples of specific descriptions found in the virtual pathway. background colours of boxes indicate: a) black = underground urban geosites; b) grey = urban geosites still linked to visible elements appearing at street level (modified after bertacchini et al., 2003). due esempi di schede di approfondimento tra quelle presenti all’interno del percorso virtuale. il diverso colore di fondo delle schede differenzia: a) nero: i geositi sotterranei urbani; b) grigio: i geositi urbani ancora legati ad elementi visibili “sopra” la città (modif. da bertacchini et al. 2003). 166 visitors can navigate through this multi-media hypertext from their computer desks and discover the cultural heritage hidden beneath the city of modena contained in the underground urban geosites that have progressively stratified during nearly two thousand years of history. the continuous possibility to update and implement the project with new data and detailed information makes the “sottosopra” project a multi-medial tool that can be adapted to changing needs and interests (bertacchini et al., 2001; 2002) and that can grow alongside the city and its cultural heritage. references ardito f. (2003) italia sotterranea de agostini ed., 256 pp. bertacchini m. (2003a) la città “sottosopra”: evoluzione geologica recente atti del conv. “la città che non si vede”, abstract, 5 giugno 2003, comune di modena. bertacchini m. (2003b) “sottosopra”: un percorso culturale-virtuale nella città di modena atti del conv. “la città che non si vede”, 5 giugno 2003, comune di modena, 14 pp. bertacchini m., coratza p. & piacente s. (2001) le “pietre del diavolo” tra borghi e castelli nell’appennino emiliano. un percorso culturale e didattico nel paesaggio ofiolitico atti del conv. naz. “le ofioliti: isole sulla terraferma”, 22-23 giugno 2001, riserva naturale monte prinzera, parma, pp. 239-250. bertacchini m., coratza p. & piacente s. (2002) paesaggi culturali. geologia e letteratura nel novecento in emilia-romagna univ. di modena e reggio e., dip. sc. terra, regione emiliaromagna, servizio valorizzazione e tutela del paesaggio. ed. l’inchiostroblù, bologna, 138 pp. bertacchini m., fontana d. & paltrinieri n. (2003) modena si svela alla rete in: “noi & l’ambiente”, modena, pp. 44-46. lugli s., fontana d., giordani n., labate d. & sacco d. (2002) stratigrafia e composizione dei sedimenti sabbiosi del sottosuolo di modena: implicazioni nell’alluvionamento della città romana. risultati preliminari atti del ii congr. naz. di archeometria, bologna, 29 gennaio-1 febbraio 2002, a.i.ar., pàtron ed., bologna, pp. 341-351. panizza m. & piacente s. (2003) geomorfologia culturale pitagora editrice bologna, 350 pp. piacente s. (1999) la conoscenza scientifica, un valore aggiunto in: g. poli (ed.), geositi, testimoni del tempo, regione emilia-romagna, bologna, pp. 234-244. m. bertacchini imp.santangelo& valutazione della pericolosità alluvionale delle conoidi del vallo di diano (salerno, italia meridionale) nicoletta santangelo1, antonio santo2, paola isabella faillace3 1 dipartimento di scienze della terra, università di napoli 2 dipartimento di ingegneria geotecnica – sezione geologia applicata, università di napoli 3 geologo, dottore di ricerca riassunto: santangelo et al., valutazione della pericolosità delle conoidi alluvionali del vallo di diano (salerno, italia meridionale). (it issn 0394-3356, 2006). l’area oggetto di questo studio è localizzata nel vallo di diano, un’ampia conca intermontana di età plio-pleistocenica situata nella parte meridionale della campania. alla base del versante orientale di questa depressione è presente un’ampia fascia detritica costituita in prevalenza da conoidi alluvionali coalescenti, con una età compresa tra il pleistocene medio e l’olocene. questa zona risulta caratterizzata da un notevole sviluppo di insediamenti urbani e attività agricole e/o industriali, che si è spesso realizzato senza tenere conto della possibile pericolosità dell’area rispetto ai processi alluvionali. l’obiettivo principale di questo lavoro è stato quello di riconoscere e di cartografare le conoidi attive e di definire la loro pericolosità, applicando un nuovo metodo recentemente proposto nella letteratura scientifica. il lavoro è stato, strutturato in più fasi. inizialmente è stato affrontato uno studio morfologico e morfometrico delle conoidi e dei loro bacini di alimentazione (27 esemplari) al fine di definire la tipologia di deposizione prevalente nelle conoidi ed il tempo di corrivazione dei bacini di alimentazione. contemporaneamente è stata effettuata un’analisi storica per cercare di comprendere lo stato di attività di questi corpi tramite un confronto tra la cartografia recente e quella storica, integrato con ricerche d’archivio che hanno documentato eventi alluvionali verificatisi nell’area negli ultimi 100 anni. il rilevamento sul campo ha consentito di raccogliere dati relativi alla tipologia dei depositi, alle interazioni esistenti tra gli apparati alluvionali e le strutture e/o infrastrutture, alla presenza di eventuali opere di sistemazione idraulica e alla loro efficacia. i dati raccolti sono stati utilizzati per definire le condizioni di pericolosità relativa tra le varie conoidi, applicando e parzialmente modificando, un metodo recentemente proposto dall’autorità di bacino del fiume po. in questo modo sono state definite quattro differenti classi di pericolosità relativa, comprese tra un alto grado (h4) ed un basso grado (h1). la maggior parte delle conoidi studiate ricade nelle classi h4 ed h3 e per almeno 8 di esse sussistono anche situazioni di alto rischio, legate all’interazione con centri urbani e altre infrastrutture. abstract: santangelo et al., alluvial fan flooding hazard assessment in the vallo di diano area (salerno, southern italy). (it issn 0394-3356, 2006). this paper deals with the problem of alluvial fan flooding in the piedmont areas of the campania region trying to apply a new method to evaluate the effective alluvial hazard conditions. piedmont areas are widespread all over the region and often present a high development of urban and/or agricultural settlements. the selected area is located at the foothill of the maddalena mountains, a nw-se trending elongated ridge which bounds to the east with the wide intramountain basin of “vallo di diano”. here a wide detrital talus made up by coalescent alluvial fans, ranging in age from middle pleistocene to holocene, is present. the geomorhological analysis firstly allowed the recognition of active and inactive alluvial fans by means of the individuation of their hydrographic apex; in this way 27 active fans have been selected for morphometrical analysis. then the main morphometric parameters (area, gradient, melton index) of each fan and hydrographic basin have been calculated in order to obtain information related to the main processes (stream or debris flow) prevailing in the basin/fan system and to calculate the concentration time. such data show that 24 out of 27 studied fans can be considered as “debris flow” dominated and that the concentration time of the hydrographic basins is always very short (lower than 1 hour). at the same time an historical analysis has been carried out to point out the state of activity of the fans during the last century. the collected data indicated that the “return time” of the main alluvial fan flooding events is more than 50 years. finally to define the relative hazard conditions among the studied fans, a recent method proposed in the scientific literature for the alluvial fans of the po river national authority has been applied, partly modifying it. four different classes of relative alluvial hazard have been distinguished from very high degree (h4) to low degree (h1). moreover, a hazard zonation inside the same alluvial fan has been proposed taking into account the main gradient variations. more than half among the studied fans belong to h4 and h3 classes and for at least 8 of them high risk conditions are determined by the interaction with urban centres and important roads. parole chiave: conoidi alluvionali, pericolosità alluvionale, colate detritiche, italia meridionale. keywords: alluvial fans, alluvial hazard, debris flow, southern italy il quaternario italian journal of quaternary sciences 19(1), 2006 3-17 1. premessa negli ultimi anni le ricerche geologiche e geomorfologiche sono state indirizzate sempre più frequentemente alla redazione di carte della pericolosità e del rischio per cause naturali. le metodologie prevedono applicazioni sia di tipo quantitativo che semiquantitativo, realizzate generalmente mediante l’utilizzo di gis sempre più sofisticati, che hanno permesso di effettuare delle perimetrazioni di dettaglio delle aree ad elevata pericolosità e rischio per fenomeni sia alluvionali che da frana. queste procedure sono ormai largamente utilizzate dai diversi enti pubblici quali per esempio le autorità di bacino. anche in campania, la redazione dei piani stralcio per l’assetto idrogeologico (psai) ha portato 4 n. santangelo, a. santo & p.i. faillace alla definizione di carte della pericolosità e del rischio soprattutto per quanto riguarda i fenomeni franosi ed i processi alluvionali in contesti di pianura. non sempre però è stato affrontato il problema della definizione della pericolosità e del rischio in contesti pedemontani laddove i processi alluvionali sono condizionati dalla presenza di conoidi attive. l’obiettivo principale di questo lavoro è stato quello di testare un metodo che permettesse di definire, agevolmente, lo stato di attività delle conoidi alluvionali in contesti pedemontani ai fini della redazione di carte della pericolosità e rischio. l’ area prescelta coincide con il settore pedemontano dei m.ti della maddalena, che si sviluppa per circa 40 km lungo il bordo orientale del bacino intermontano del vallo di diano ed è caratterizzato dalla presenza di numerose conoidi alluvionali coalescenti. la scelta è stata dettata anche dal fatto che su tale area alcuni degli scriventi hanno svolto attività di ricerca da più di un decennio e quindi per tali conoidi si possedevano dati storici su precedenti alluvioni, numerosi dati geomorfologici e stratigrafici ed una base vettoriale (volo del 1991) gentilmente resa disponibile dalla comunità montana del vallo di diano. le direttive seguite per definire lo stato di attività delle conoidi sono quelle proposte dalla fema (federal emergency management agency) del national research council degli stati uniti d’america (nrc, 1996). esse consistono in un’analisi geomorfologica dettagliata di carte topografiche in scala adeguata, supportata da dati di rilevamento. in particolare prevedono il riconoscimento delle porzioni attive/inattive di conoidi coalescenti attraverso l’identificazione dell’apice idrografico e dell’età dell’ultima attivazione; quest’ultima viene definita attraverso un’analisi storica e/o stratigrafica che dimostri l’esistenza di attività negli ultimi 100 anni (special flood hazard areas). e’ stato inoltre effettuato un rilevamento di dettaglio che ha consentito di raccogliere dati relativi alla tipologia dei depositi, alle interazioni esistenti tra gli apparati alluvionali e le strutture e/o infrastrutture, alla presenza di eventuali opere di sistemazione idraulica e alla loro efficacia. questo studio è stato integrato con un’analisi morfometrica delle conoidi e dei loro bacini di alimentazione, per definire i tempi di corrivazione dei bacini e per comprendere i processi deposizionali prevalenti nella messa in posto delle conoidi. i dati raccolti sono stati infine utilizzati per valutare la pericolosità rispetto ai processi alluvionali dell’area di studio seguendo e, parzialmente modificando, il metodo proposto dall’autorità di bacino del po per la redazione del psai e riportato in sanna (2003). 2. inquadramento geologico dell’area il vallo di diano è una estesa depressione strutturale dell’appennino campano-lucano, allungata in direzione appenninica per circa 37 km, formatasi in seguito all’azione di importanti faglie regionali attive durante il pliocene-pleistocene (santangelo, 1991; ascione et al., 1992). in questo periodo il vallo di diano è stato sede di un grande bacino lacustre che successivamente si è trasformato in un’area palustre ed è stato bonificato in tempi storici per opera dei borboni (1800)1. esso è bordato ad occidente dai massicci calcarei, prevalentemente cretacici, del cilento (m.te cervati, m.ti alburni, m.ti della motola) e ad oriente dai m.ti della maddalena, una dorsale calcareo dolomitica di età triassico-giurassica, su cui poggiano stratigraficamente calcari pseudosaccaroidi, calciruditi e calcareniti di età maastrichtiano-eocenica. localmente sono presenti lembi trasgressivi di depositi arenaceo-argillosi di età miocenica mentre, nella zona meridionale della dorsale, tra sala consilina e padula, affiorano in finestra tettonica al di sotto delle unità carbonatiche, depositi calcareo-silico marnosi delle unità lagonegresi (fig. 1). lungo il bordo orientale del vallo è presente un’ampia fascia pedemontana che fa da raccordo tra i m.ti della maddalena ed il fondovalle; essa è costituita da diversi sistemi di conoidi alluvionale coalescenti, all’interno delle quali sono state riconosciute diverse generazioni di corpi sedimentari (santangelo, 1991). le più antiche sono attribuite al pleistocene medio superiore e sono ormai inattive mentre quelle recenti (pleistocene superiore olocene) costituiscono il raccordo con l’attuale fondovalle. i dati pluviometrici disponibili sull’area (pluviometro di sala consilina, 560 m.s.l.m.) analizzati sul periodo 1921-1950 (lippmann – provansal, 1987) riportano precipitazioni medie mensili non superiori ai 120 mm (concentrate nei mesi invernali ) ed un numero di giorni non piovosi superiore a 75 durante la stagione estiva. la piovosità media annuale, nello stesso periodo è compresa tra 1100 e 1250 mm annui. 3. analisi geomorfologica la prima fase della ricerca è stata rivolta al riconoscimento e alla perimetrazione delle conoidi alluvionali di prima e di seconda generazione e dei relativi bacini idrografici (fig. 1). 1 i primi tentativi di bonifica delle terre italiane iniziarono in epoca preromana ad opera dei pelasgi che tentarono di affrontare la bonifica del vallo con opere di una certa importanza, allargando gli inghiottitoi. i greci in seguito dovettero affrontare la bonifica di molte zone, e fra queste il vallo di diano. ai romani sono da attribuire le prime importanti opere; sarebbe, infatti, da attribuire a loro l’incisione della soglia del vallo presso polla (il gatta , riprendendo la notizia da g.b. pacichelli memorie dei viaggi in europa scrive: “ivi per darli più libero il trabocco ne poterono i romani aprire il varco”, ed ancora iannicelli a. sala consilina ed il vallo di diano scrive: ‘i romani iniziarono la regolazione delle acque col taglio della roccia presso campestrino’) e l’apertura di un lungo canale (oltre 2 km), detto fossato o intagliata, e di un ponte che lo sormonta (nel caso che si ritenga autentica un’iscrizione che afferma: pontem et foxatum roma p. fecit = la potenza di roma fece il ponte e il fossato). durante la dominazione borbonica (1786), ad opera di ferdinando iv di borbone, che diede incarico all’architetto pollio e successivamente al cavalier grasso, furono portati a termine lavori di bonifica (1796) tendenti a regolare i corsi d’acqua naturali, che possono ritenersi importanti per l’epoca (ass, busta 1595 vallo di diano). 5valutazione della pericolosità alluvionale ... fig. 1schema geologico e schema geomorfologico dell’area in studio. 1) depositi lacustri (olocene); 2) conoidi alluvionali attive (pleistocene sup. olocene) e numero di riferimento; 3) conoidi alluvionali inattive (pleistocene medio sup.); 4) flysch (miocene); 5) successioni calcareo-silico-marnose (giurassico sup. eocene); 6) depositi carbonatici (giurassico inf. eocene); 7) dolomie (triassico); 8) depositi carbonatici (cretaceo inf. sup.); 9) faglia; 10) sovrascorrimento; 11) bacino idrografico. geological and geomorphological sketches of the studied area. 1) lacustrine deposits (holocene); 2) active alluvial fan (upper pleistocene holocene) with referring number; 3) inactive alluvial fan (middle upper pleistocene); 4) flysch deposits (miocene); 5) marl and calacareous marls (upper giurassic eocene); 6) limestones (lower giurassic eocene); 7) dolomites (triassic); 8) limestones (lowerupper cretaceous.); 9) fault; 10) thrust; 11) hydrographic basin. 6 le conoidi di prima generazione, più antiche, affiorano solo in alcuni settori (a sud dell’abitato di padula, in corrispondenza del m.te tempone, ed a sud di m.te serra petrizzo) a quote comprese tra 520 e 650 m s.l.m. esse risultano inattive, profondamente reincise da alcuni corsi d’acqua in quanto sono state fagliate e sollevate per l’intensa attività tettonica registrata durante il tardo quaternario dalla faglia bordiera dei m.ti della maddalena. in particolare tale attività è testimoniata dalla presenza di scarpate di faglia che tagliano le conoidi nei pressi di sala consilina e dalla dislocazione di depositi lacustri ascritti al pleistocene medio, nei pressi di atena lucana.(santangelo, 1991; ascione et al., 1992). per tale motivo i depositi di questi antichi conoidi, ormai sospesi, sono conservati soltanto nella loro porzione apicale e sono costituiti da conglomerati ben cementati a clasti carbonatici, spesso ricoperti da suoli argilloso sabbiosi fortemente arrossati. le conoidi di seconda generazione sono, al contrario, rappresentate da ampi “ventagli”, di estensione molto diversa in funzione dei loro bacini alimentatori e nel complesso con un gradiente di pendio mediobasso. risultano costituite da ghiaie e conglomerati poco cementati a clasti carbonatici che contengono locali lenti di sabbie ed argille di colore marrone rossastro. dal punto di vista morfologico questi apparati multipli sono sia del tipo “sovrapposto” che del tipo “incastrato” (sensu bull, 1968): nel primo caso l’apice topografico e l’apice idrografico coincidono e i corpi deposizionali più recenti ed ancora attivi sono localizzati in zona apicale (fig. 2a). nel secondo caso l’apice topografico e l’apice idrografico non coincidono e la conoide attiva è localizzata in zona distale rispetto al fronte montuoso (fig. 2b). attraverso un attento esame dell’andamento delle curve di livello sulle carte topografiche c.t.r. in scala 1:10.000 della comunità montana del vallo di diano (1991), e una analisi fotointerpretativa, sono state riconosciute 27 conoidi attive; per ognuna di esse sono stati individuati l’apice idrografico ed eventuali lobi di deposizione relitti. il lavoro è stato eseguito con il supporto del software gis arc view. l’utilizzo di questo software ha inoltre consentito il calcolo dei principali parametri morfometrici delle conoidi e dei loro relativi bacini di alimentazione (tab. 1 e tab. 2). tali parametri sono stati utilizzati sia per risalire alla tipologia di trasporto prevalente nella messa in posto delle singole conoidi, sia per calcolare alcuni indici necessari per valutare la loro pericolosità . 3.1. tipologia di trasporto per individuare la tipologia di trasporto prevalente è stato utilizzato un metodo indiretto di tipo morfometrico, basato sulle relazioni esistenti tra la pendenza della conoide (ic) ed un indice adimensionale (indice di melton, mel) indicante la rugosità del bacino. si è utilizzato questo criterio morfometrico in quanto in campagna, purtroppo, le esposizioni di sezioni stratigrafiche naturali sono rare. la definizione del tipo di trasporto prevalente (stream flow, misto, debris flow) risulta utile in quanto consente di avere delle informazioni sull’intensità relativa degli eventi alluvionali. in questo modo possono essere individuate le conoidi a prevalente trasporto da debris flow che rappresentano le aree potenzialmente soggette ad eventi alluvionali più intensi. i primi studi mirati a definire i rapporti tra la forma delle conoidi alluvionali e quella dei loro bacini di alin. santangelo, a. santo & p.i. faillace fig. 2 conoidi alluvionali sovrapposte (a) ed incastrate (b) con ubicazione dell’apice topografico e dell’apice idrografico (da bull, 1968 modificato). superimposed alluvial fans (a) and entrenched alluvial fans (b) with location of the topographic and hydrographic apex (by bull, 1968 modified). 7 mentazione si devono a melton (1965) che constatò che la pendenza di una conoide non dipende esclusivamente dalla variazione della granulometria del materiale lungo la superficie di una conoide come sostenuto da eckis (1928) e blissenbach (1954), ma che invece essa è strettamente legata all’area e all’energia di rilievo del suo bacino di alimentazione. melton osservò che le conoidi alluvionali più estese e a minor pendenza sono legate esclusivamente a processi fluviali ed associate a grandi bacini di alimentazione con bassa energia di rilievo. invece conoidi più piccole e pendenti, dominate da meccanismi di messa in posto di tipo debris flow sono associate a bacini di area molto minore e ad elevata energia di rilievo. da questo studio egli riuscì a ricavare un indice adimensionale per caratterizzare i bacini di alimentazione, denominato indice di melton (mel), dato dal rapporto: mel = ab –0,5 (qb max qb min) (1) dove qb max e qb min rappresentano rispettivamente valutazione della pericolosità alluvionale ... tab. 1 parametri morfometrici dei bacini idrografici. ab = superficie del bacino; σl = lunghezza totale del corso d’acqua; qb max = quota massima; qb min = quota minima; ib = gradiente medio. morphometric parameters of the hydrographic basins. ab = drainage basin area; σl = total length of the streams; qb max = maximum elevation; qb min = minimum elevation; ib = mean gradient. ab σl qbmax qbmin bacini (km2) (km) (m) (m) ib (%) 1 1,4 2,9 1200 540 29,5 2 0,75 0,9 1110 470 17,3 3 1,45 2,8 1100 520 22,6 4 1,78 2,9 1221 480 26,6 5 5,5 10,2 1285 470 9,22 6 0,35 0,3 680 500 33,3 7 2,94 4,6 1289 480 10,7 8 8,37 12 1289 480 17,4 9 4,87 10 1310 480 11,1 10 2,63 6,1 1230 490 23,7 11 6,93 18,9 1450 530 19,1 12 1,2 3,2 920 470 23,7 13 2,05 6 1350 510 16,3 14 0,76 1,6 1240 550 2 15 0,07 0,3 950 650 50 16 2,76 7,4 1410 600 20 17 0,9 1,5 1460 600 47 18 0,65 2,1 1340 550 42,3 19 1 2,4 1490 570 25 20 3,66 11,1 1410 560 21,6 21 0,73 1,9 1000 530 28,4 22 6,75 16,9 1450 530 9,62 23 4,4 9,68 1290 550 16,2 24 2,99 4,6 1245 550 17,8 25 6,98 19,4 1310 600 19,9 26 3,59 10 1440 570 13,8 27 4,39 12,6 1500 550 23,4 tab. 2 parametri morfometrici delle conoidi alluvionali del vallo di diano. ac = superficie della conoide; qc max = quota massima; qc min = quota minima; ic = gradiente medio. morphometric parameters of alluvial fans. ac = fan area; qc max = apex elevation; qc min = elevation of fan toe; ic = mean gradient. ac qcmax qcmin bacini (km2) (m) (m) ib (%) 1 0,37 560 450 13,7 2 0,13 470 450 5 3 0,25 520 450 8,3 4 0,14 480 450 6 5 0,36 470 450 2,67 6 0,04 500 450 20 7 0,21 480 450 5,3 8 0,46 480 450 3,9 9 0,33 480 450 5,8 10 0,41 490 450 5,2 11 1,3 530 450 5,8 12 0,2 470 450 3,5 13 0,44 510 450 7,9 14 0,55 550 450 12,3 15 0,4 600 450 22,5 16 0,75 620 450 14,3 17 0,32 590 460 21,3 18 0,18 540 460 13,7 19 0,77 570 460 10,5 20 0,6 560 460 10 21 1,22 530 470 5,9 22 1,46 530 460 4,3 23 1,22 550 470 5,7 24 0,57 550 470 4,7 25 6,92 580 470 3,07 26 3,4 570 470 3,4 27 1,48 550 480 3,5 8 la quota massima e minima del bacino, ed ab la superficie del bacino stesso, e lo confrontò con la pendenza ic delle conoidi, ricavando l’equazione: ic (°) = a [ (qb – qb min) ab –0,5] n . (2) dove a ed n sono dei parametri adimensionali calcolati su base statistica. questa relazione è stata in seguito utilizzata da diversi autori (ryder, 1971; kostaschuk et al., 1986; jackson et al.,1987; hrvey, 1988; pasuto et al ,1992; marchi et al., 1993;1995; d’agostino, 1996) per distinguere le conoidi sulla base della tipologia di deposizione prevalente. tali studi, effettuati in diversi contesti climatici ed ambientali (stati uniti, canada, messico, nuova zelanda; kostaschuk et al., 1986; ryder, 1971; jackson et al., 1987; harvey, 1988; de scally & owens, 2004) e supportati da un’analisi di campo, hanno dimostrato una buona attendibilità del metodo. in italia la relazione ic/mel è stata applicata da pasuto et al. (1992) su sistemi di conoide dell’avisio, nelle dolomiti, unitamente ad evidenze emerse dal rilevamento sul terreno, per discriminare i sistemi bacinoconoide a rischio di debris flow. marchi et al. (1993; 1995) hanno utilizzato il medesimo approccio per sette zone delle alpi orientali, confermando le osservazioni morfometriche con osservazioni storiche sui fenomeni di elevata intensità. sulla base di questi studi si è provato ad applicare questa metodologia anche alle conoidi del vallo di diano. per ogni sistema “bacino-conoide” sono stati quindi calcolati i due parametri, mel e ic° (tab. 3). prima di procedere con la comparazione fra i due parametri, è stata valutata la significatività della correlazione tra le due variabili; l’analisi della correlazione ha evidenziato una valore di r di pearson molto significativo (p < 0.01) e pertanto si è proceduto alla costruzione del grafico di fig. 3. la distribuzione ottenuta risulta simile a quella riscontrata dallo studio di pasuto et al. (1992) e da marchi et al. (1993) che, sulla base di riscontri sul campo, hanno evidenziato che la pendenza delle conoidi risulta influenzata dalla tipologia dei processi deposizionali piuttosto che dalle caratteristiche litologiche dei bacini di alimentazione. gli aa. hanno differenziato le conoidi da loro studiate in tre gruppi principali: quelle a più basso gradiente e con indici di melton (mel) inferiori a 0.25 risultano caratterizzate da trasporto prettamente fluviale, quelle con mel maggiore di 0.5 da processi tipo debris flows; quelle con gradiente intermedio (0.25 < mel < 0.5) rappresentano, invece, le conoidi originate da un trasporto di tipo misto. l’analisi del grafico mel-ic (fig. 3) consente di affermare che il vallo di diano è caratterizzato da un cospicuo numero di conoidi con valori medi sia di pendenza sia di indice di melton, mentre esistono due gruppi estremi che potrebbero essere associati rispettivamente a processi prevalenti di tipo debris flow (n° 14, 15, 17, 18, 19) e di tipo selettivo (n° 5, 8 e 25). per discriminare in maniera più precisa tra questi due gruppi si può seguire il suggerimento di d’agostino n. santangelo, a. santo & p.i. faillace tab. 3 gradiente medio, indice di melton; ed equazione di d’agostino di tutte le conoidi studiate. mean gradient (ic), melton’s ruggedness number (mel) and d’agostino’s equation for all the studied fans. bacini ic (°) mel) 7-14mel 1 7,8 0,56 -0,80923 2 2,9 0,74 -3,34612 3 4,7 0,48 0,256707 4 3,4 0,56 -0,77564 5 1,5 0,35 2,13476 6 11,3 0,3 2,740423 7 3 0,47 0,394543 8 2,2 0,28 3,085162 9 3,3 0,38 1,734475 10 3 0,46 0,61175 11 3,3 0,35 2,107293 12 2 0,41 1,248913 13 4,5 0,59 -1,21354 14 7 0,79 -4,08078 15 12,7 1,13 -8,87451 16 8 0,49 0,174122 17 12 0,91 -5,69127 18 7,8 0,98 -6,71824 19 6 0,92 -5,88 20 5,7 0,44 0,77977 21 3,38 0,55 -0,70131 22 2,5 0,35 2,042486 23 3,3 0,35 2,061064 24 2,7 0,4 1,372996 25 1,7 0,27 3,237655 26 2 0,46 0,571642 27 2 0,45 0,652256 fig. 3 – classificazione delle conoidi alluvionali del vallo di diano sulla base della pendenza della conoide e dell’indice di melton. classification of the alluvial fans of vallo di diano on the basis of the fan slope and the melton’s ruggedness number. (1996) secondo cui, in via cautelativa, i trasporti di tipo misto possono essere accorpati nei debris flow/flood utilizzando come linea di separazione tra le due categorie di bacini/conoide la retta di equazione: ic° = 7 – 14mel applicando tale equazione al grafico ottenuto per le conoidi del vallo di diano si può osservare come cadano al di sotto di questa retta, e cioè soddisfino la disequazione ic° < 7-14 mel, soltanto le conoidi n° 5, 8 e 25 che risultano quindi le sole ad essere caratterizzate da processi di tipo selettivo. (fig. 3 e tab. 3) 3.2. tempo di corrivazione i parametri morfometrici dei bacini sono stati utilizzati anche per calcolare il tempo di corrivazione, cioè il tempo impiegato dalle acque d'afflusso meteorico a raggiungere la sezione di chiusura, partendo dai punti più alti e più lontani del bacino. questo parametro, che è funzione della morfologia, delle litologie affioranti e della copertura vegetale, è stato calcolato utilizzando la formula di giandotti (1934): tc(h) = [4√ab + 1.5lp] / [0.8 √(qbm-qb min)] dove ab rappresenta la superficie del bacino, lp la lunghezza dell’asta principale, qbm la quota media del bacino e qb min la quota minima del bacino. per il calcolo del tc è stato necessario calcolare la qbm del bacino la cui formula è: qbm = σ [ai qi/2]/ab dove qi = quota (m.s.l.m.) delle singole fasce altimetriche, pari alla media delle quote delle due isoipse che le delimitano; ai = area (in m 2) delle singole fasce di altitudine. per quest’ultimo parametro è stata considerata un’equidistanza tra le isoipse di 50 m e le aree racchiuse tra di esse sono state calcolate con l’utilizzo di un software gis . dai risultati (tab. 4) si evince che la maggior parte dei corsi d’acqua impiega dai 30 ai 50 minuti per percorrere l’intero bacino e raggiungere i settori apicali delle conoidi alluvionali. tali tempi dunque risultano estremamente bassi; solo per tre conoidi, e precisamente per la 10, la 22 e la 25 essi superano di poco l’ora, ma sono comunque da ritenersi tempi molto brevi soprattutto in caso di eventi idrologici estremi. 4. analisi dello stato di attività per individuare i settori di conoidi alluvionali attivi negli ultimi 100 anni è stato effettuato un confronto tra la situazione topografica attuale e quella risultante dalla cartografia storica (i.g.m.i., 1908). contemporaneamente sono state svolte ricerche presso archivi di stato ed altri enti pubblici (genio civile, istituti idrografici, comunità montana) per recuperare documenti che testimoniassero eventi passati, sono state raccolte in sito testimonianze degli abitanti e, solo in alcuni casi, sono stati censiti degli eventi alluvionali che hanno coinvolto siti archeologici o monumentali e alcune costruzioni. dal punto di vista cartografico si è analizzato soprattutto l’andamento dell’alveo principale, per evidenziare eventuali spostamenti del tracciato fluviale. in alcuni casi, inoltre, sono state riconosciute evidenze di fenomeni di deposizione recente sul corpo della conoide. questi ultimi sono stati individuati grazie alla presenza di numerose anomalie delle isoipse sulle basi topografiche in scala 1:10.000 del 1990, che delineavano la presenza di antichi lobi di distribuzione (fig. 4). in parecchi casi si è poi riscontrato che sulla cartografia storica del 1908, tali aree risultavano caratterizzate da deposizione in atto. casi significativi, sono quelli del tratto terminale del vallone dei serpenti (n° 9), quello del vallone carbonaro (n° 10) in cui sono molto ben evidenti i lobi deposizionali attivi nel 1908 e quello del vallone della cerasa (n° 11). il tratto terminale del vallone s. angelo (n° 23), già a fine xviii secolo iniziava ad approfondirsi con forti evidenze di attività deposizionale. 9valutazione della pericolosità alluvionale ... tab. 4 parametri morfometrici utilizzati per il calcolo del tempo di corrivazione dei bacini (tc). ab = superficie del bacino; lp = lunghezza dell’asta principale; qb m = quota media; qb min = quota minima; tc = tempo di corrivazione. morphometric parameters used for calculating the hydrographic basin concentration time (tc). ab= drainage basin area; lp= length of main stream; qb m = mean elevation; qb min = minimum elevation; tc = concentration time. ab lp qbma qbmin tc bacino (km2) (km) (m) (m) (minuti) 1 1,4 1,67 897 560 30’ 2 0,75 0,87 715 470 23’ 3 1,45 2,3 873 520 33’ 10 2,63 3,12 767 490 50’ 11 6,93 6,32 1050 530 66’ 12 1,2 1,91 615 470 45’ 13 2,05 3,44 1001 510 37’ 14 0,76 0,82 833 550 21’ 15 0,07 0,31 770 650 11’ 16 2,76 3,57 1136 600 39’ 17 0,9 1,34 1063 600 20’ 18 0,65 1,39 852 550 23’ 19 1 2,36 1010 570 27’ 20 3,66 4,08 1019 560 48’ 21 0,73 2 695 530 38’ 22 6,75 5,2 989 530 64’ 23 4,4 3,78 941 550 53’ 24 2,99 3,67 801 550 59’ 25 6,98 4,98 944 600 73’ 26 3,59 4,84 1070 570 50’ 27 4,39 4 1063 550 48’ durante il lavoro di rilevamento è stato poi possibile raccogliere dagli anziani del luogo delle testimonianze orali relative ad eventi alluvionali che hanno interessato ripetutamente (fine 1800, 1922, 1950, 1962, 2004) le zone delle conoidi n° 8, 16, 17, 18, 19 ed hanno comportato sia fenomeni di trasporto solido che allagamenti dei primi piani degli edifici. il caso più esemplare e meglio documentato che testimoni l’attività storica di queste conoidi resta comunque quello della conoide del t. fabbricatore (n° 25), nella cui zona apicale è stata costruita nel 1306 la certosa di padula, uno dei complessi monastici più importanti dell’italia meridionale. prima che il corso d’acqua fosse deviato, esso scorreva a poca distanza dalla cinta muraria, e ciò è stato narrato anche in alcuni documenti storici (genio civile, 1858; pesce, 1889). nel 1857 l’abbadia fu colpita da un alluvione che ricoprì parte delle sue mura esterne e parte del cortile interno (fig. 5). oltre a questo evento, ve ne sono stati altri che hanno interessato la certosa, e precisamente durante il 1859, 1876, 1881, 1900, come testimoniano altri documenti storici (budetta et al., 2000). a seguito di ciò il consorzio di bonifica del vallo di diano effettuò la sistemazione idraulica del t. fabbricatore e la sua deviazione per evitare ulteriori inondazioni all’interno della certosa. sulla base dei confronti cartografici e delle fonti storiche raccolte è dunque possibile affermare che, negli ultimi 100 anni, la maggior parte delle conoidi studiate è stata soggetta a sensibili modificazioni e, in taluni casi, è stata interessata da eventi alluvionali significativi; pertanto tali aree, secondo la definizione del nrc (1996), sono da considerarsi sicuramente attive. 5. censimento delle opere idrauliche i dati sinora raccolti consentono di affermare che tutte le conoidi del settore orientale del vallo di diano risultano attive (anche se gli eventi alluvionali estremi, dedotti in base all’analisi storica, hanno tempi di ritorno maggiori di 50 anni) e sono sottese da bacini con tempi di corrivazione molto bassi; la maggior parte di esse inoltre, presenta un’alta probabilità ad essere interessata da fenomeni tipo debris flow. per procedere ulteriormente nella individuazione delle aree a maggior grado di pericolosità e rischio sono stati eseguiti dei sopralluoghi mirati ad un censimento delle modificazioni antropiche degli ultimi decenni, sia in termini di opere idrauliche (deviazioni dei corsi d’acqua, sistemazioni dei bacini imbriferi ecc.), sia per quanto riguarda le interazioni che le conoidi hanno con le aree di recente espansione dei centri abitati. questi ultimi infatti, negli ultimi trenta anni, hanno subito una notevole espansione anche verso i settori montuosi, andando ad interferire con le conoidi attive e determinando, talora, situazioni di alto rischio. 10 n. santangelo, a. santo & p.i. faillace fig. 4 a) le anomalie delle isoipse suggeriscono la presenza di un lobo di deposizione; b) il confronto con la cartografia storica del 1908 testimonia la presenza di deposizione attiva nella stessa area. 1) lobo deposizionale; 2) alveo attivo. a) anomalies in the contour lines suggest the presence of an ancient depositional lobe; b) comparison with historical maps shows that deposition was active in the same area during 1908. 1) depositional lobe; 2) active channel. fig. 5 portale di ingresso della certosa di padula completamente sepolto dagli eventi alluvionali di fine 1800. foto storica da budetta et al., 2000). entrance of padula’s abbey buried by sediments deposited during the alluvial events of the end of 1800. historical photo by budetta et al., 2000). 11valutazione della pericolosità alluvionale ... f ig . 6 c a rt a g e o m o rf o lo g ic a d e lle c o n o id i d e l v a llo d i d ia n o . 1 ) c o n o id e a tt iv a e s u o n u m e ro d i r ife ri m e n to ; 2 ) a p ic e id ro g ra fic o ; 3 ) a re a c o n e vi d e n za d i a g g ra d a zi o n e in e p o c a s to ri c a ; 4 ) lo b i d e p o si zi o n a li a tt iv i; 5 ) lo b i d i d e p o si zi o n e r e lit ti ; 6 ) tr a c c ia to d e l c o rs o d ’a c q u a d e su n to d a lla c a rt o g ra fia d e l 1 9 0 8 ; 7 ) a re e d i d e p o si zi o n e a tt iv a n e l 1 9 0 8 ; 8 ) su b st ra to c a lc a re o ; 9 ) a lv e o in c a ssa to ; 1 0 ) p ro b a b ile l in e a d i d e flu ss o i n c a so d i e so n d a zi o n e ; 1 1 ) a lv e o s tr a d a s u c o n o id e ; 1 2 ) b ru sc a d e vi a zi o n e d i a lv e o n a tu ra le e /o a rt ifi c ia le ; 1 3 ) a lv e o c o n s is te m a zi o n e t ra sv e rs a le e /o la te ra le ; 1 4 ) tr a tt o d i s tr a d a o a u to st ra d a p o te n zi a lm e n te e so n d a b ile ; 1 5 ) p u n to c ri ti c o p e r ri d o tt a s e zi o n e d e ll’ a lv e o . g e o m o rp h o lo g ic al m ap o f th e a llu vi al f an s o f th e v al lo d i d ia n o a re a. 1 ) a c ti ve a llu vi al f an w it h r e fe rr in g n u m b e r; 2 ) h yd ro g ra p h ic a p e x; 3 ) p o rt io n o f al lu vi al f an w it h e vi d e n c e o f ag g ra d at io n s d u ri n g h is to ri c al t im e ; 4 ) ac ti ve d e p o si ti o n al l o b e s; 5 ) in ac ti ve d e p o si ti o n al l o b e s; 6 ) tr ac k o f ri ve r in fe rr e d f ro m h is to ri c al m ap ; 7 ) ar e as o f ac ti ve d e p o si ti o n d u ri n g t h e 1 9 0 8 ; 8 ) lim e st o n e s ; 9 ) e n tr e n c h e d a c ti ve c h an n e l; 1 0 ) p ro b ab le lo w p at h d u ri n g a n a llu vi al e ve n t; 1 1 ) c h an n e l s u b st it u it e d b y a ro ad o n t h e a llu vi al f an ; 1 2 ) ab ru p t d e vi at io n o f n at u ra l a n d /o r ar ti fic ia l c h an n e l; 1 3 ) ac ti ve c h an n e l w it h t ra n sv e rs al a n d /o r la te ra l h yd ro lo g ic al w o rk s; 1 4 ) st re tc h o f ro ad o r m o to rw ay p o te n ti al ly f lo o d ab le ; 1 5 ) c ri ti c al p o in t fo r re d u c e d c h an n e l s e c ti o n . in figura 6 ed in tabella 5 è riportata la sintesi di queste osservazioni. per quanto riguarda le opere idrauliche, si è potuto constatare che i canali alimentatori delle conoidi n° 8, 24, 25, 26 sono stati cementificati e imbrigliati nella porzione apicale; pertanto le loro naturali aree di recapito sono state spostate artificialmente più a valle. in alcuni casi, come al t. fabbricatore (n° 25), la realizzazione di nuovi alti argini artificiali e di briglie trasversali ha sicuramente ridotto di molto la possibilità di esondazione e di trasporto solido anche se, in questa ed in altre situazioni, è stato osservato un parziale interrimento delle briglie. in altri casi invece (n° 15, 16, 17), in cui gli apici idrografici delle conoidi sono localizzati in pieno centro abitato (sala consilina), gli alvei naturali purtroppo sono stati completamente ricoperti (tombati) creando così situazioni di alta possibilità di alluvionamento in caso di precipitazioni intense, come del resto evidenziato dalle testimonianze storiche raccolte. particolare attenzione è stata rivolta anche alla interazione tra gli alvei e la rete stradale (tab. 5 e fig. 6); in primo luogo sono stati cartografati i principali sottopassi evidenziando i punti in cui questi si presentavano palesemente sottodimensionati o parzialmente interrati (cfr. casella 15 in fig. 6). inoltre è stata evidenziata la presenza di alvei strada (conoidi n° 1, 3, 11, 19, 20, 23), cioè di strade che, avendo parzialmente o completamente sostituito l’alveo principale, possono fungere da recapito preferenziale di possibili fenomeni di esondazione e di trasporto solido. infine sono stati censiti tutti i punti in cui i lobi attivi delle conoidi interferiscono direttamente con strade trasversali o con case rurali sparse, in assenza di opere di protezione (conoidi n° 14,15, 16, 17, 19, 20, 22, 23, 25, 27) ed i punti in cui i gli alvei naturali e/o artificiali subiscono delle brusche variazioni di tracciato con la possibilità quindi di tracimazioni (conoidi n° 1, 10, 13, 23). per tutte le conoidi inoltre, sono state misurate le altezze degli argini nelle zone apicali ed è stata fatta una stima del volume massimo dei clasti visibili nell’alveo. infine, la prima colonna della tab. 5 sintetizza tutte le informazioni raccolte relativamente alle opere di sistemazione e difesa, raggruppandole in tre categorie in funzione del loro grado di mitigazione dei fenomeni alluvionali (inefficaci o assenti, parzialmente migliorative, migliorative) come proposto dall’autorità di bacino del po (sanna, 2003). tutte le informazioni su citate hanno contribuito alla definizione della pericolosità e del rischio come descritto nel paragrafo successivo. 6. pericolosità alluvionale della fascia pedemontana dei monti della maddalena per definire lo stato di pericolosità rispetto ai processi alluvionali della zona in studio è stato seguito e parzialmente modificato il metodo proposto recentemente dall’autorità di bacino del po per la valutazione della pericolosità sulle conoidi alluvionali, riportato in sanna (2003) esso prevede la valutazione di una serie di parametri, indicativi delle caratteristiche fisiografiche del bacino imbrifero, della quantità del materiale trasportato, dell’energia di trasporto, della ricorrenza dell’evento e della presenza e funzionalità di eventuali opere di sistemazione. questi parametri vengono integrati a coppie, in maniera progressiva, utilizzando una serie di matrici (tab. 6). la prima matrice considerata (tab. 6a) è quella relativa alla “massa solida (m)” definita dalla relazione esistente tra la superficie del bacino (divisa in tre classi: < 4, 4-20, > 20 km2) ed il rapporto percentuale tra la superficie della conoide (ac) e la superficie del bacino 12 tab. 5 sintesi dei dati di rilevamento. a = opere assenti; pm = opere parzialmente migliorative; m = opere migliorative; sc = strada comunale; a3 = autostrada sa-rc; ss = strada statale; ca = centro abitato; c = case sparse. synthesis of the data survey. a = absent; pm =; partly improving hydrological works; m = improving hydrological works; sc = city road; a3 = motorway sa-rc; ss = state road; ca = town or village; c = scattered houses. tipologie interazione dimensione volume conoidi opere con infraalveo medio idrauliche strutture (hxl) (mxm) clasti (m3) 1 a sc 1,5 2 0,024 2 a a3 1 1 0,002 3 pm c + a3 2,5 4 0,024 4 a ss19 1,5 1,5 0,002 5 pm 1,5 2,5 0,002 6 pm ss19 + a3 1 1 0,024 7 pm a3 1,5 4 0,072 8 m 6 5 0,096 9 pm ss19+a3+c 2 2 0,036 10 pm 1,5 1,5 0,002 11 pm sc 2 4 0,006 12 a sc + c 0,002 13 pm sc + ss19 2 4 0,006 14 pm ss19 4 6 0,002 15 a sc + ca tombato 0,036 16 a sc + ca tombato 0,040 17 a sc + ca tombato 0,192 18 a sc + ca tombato 0,096 19 a sc + c 1,5 3 0,006 20 a sc + c 1,5 2 0,024 21 a sc 2 4 0,006 22 a sc + c 3 4 0,008 23 a 1,5 2,5 0,006 24 pm sc + c tombato 0,048 25 m sc + c 2 3 0,012 26 m tombato 0,012 27 a sc + c tombato 0,014 n. santangelo, a. santo & p.i. faillace (ab). in questo modo vengono definite tre categorie di bacini che vanno da m1 a m3 (per i dati morfometrici si rimanda alle tab. 1, 2 e 3). la seconda matrice (tab. 6a) è relativa alla “tipologia del processo (t)” e viene ottenuta incrociando il parametro “massa solida” con “l’indice di melton” (cfr. tab. 3) che, come abbiamo già visto, consente di avere informazioni riguardo ai processi di trasporto prevalenti nelle conoidi in studio. in effetti nel metodo proposto viene considerata una suddivisione tra processi fluviali (mel < 0.25), misti (0.25 <mel <0.35) e debris flow (mel > 0,35) e vengono differenziate cinque diverse categorie (da t1 a t5). nel nostro caso, sulla base di quanto discusso nel paragrafo 2, in via cautelativa, si è preferito usare come valore discriminante tra le conoidi fluviali e quelle a debris flow prevalente, l’equazione proposta da d’agostino (1996). pertanto questa matrice è stata modificata ottenendo tre categorie (da t1 a t3). la terza matrice (tab. 6c) definisce il parametro “massa critica (mc)” e deriva dall’incrocio tra il parametro t ed il volume medio-massimo dei clasti (espresso in m3), rilevato sul campo (cfr. tab. 5), mentre la quarta matrice (tab. 6d) è relativa alla “intensità (i)“ e risulta dall’incrocio tra la massa critica e la pendenza della conoide (vengono considerate tre classi di pendenza: < 7°, 7-15°, > 15°; per i valori relativi ad ogni conoide si veda la tabella 3). la quinta matrice (tab. 6e) è quella della “pericolosità (p)” e si ottiene incrociando i dati relativi all’intensità con quelli legati al tempo di ritorno degli eventi che vengono suddivisi in tre classi: ricorrenti (r1, < 10 anni), occasionali (r2, tra 10 e 50 anni) ed eccezionali (r3, > 50 anni). in questo modo si definiscono le diverse classi di pericolosità. la sesta ed ultima matrice (tab. 6f) è quella della “pericolosità effettiva (h) ” che tiene conto della presenza di eventuali opere di difesa e del loro stato di conservazione. vengono considerate tre tipologie di opere (migliorative, parzialmente migliorative, inefficaci o assenti) e si arriva così a discriminare tra quattro classi di pericolosità: bassa, moderata, alta e molto alta (h1h4). la tabella 7 e la figura 7 riportano la sintesi di tutti questi passaggi. come si può osservare, su 27 conoidi alcune hanno un grado di pericolosità basso o moderato dovuto anche ai recenti lavori di sistemazione idraulica di alcuni corsi d’acqua (n° 8-25-26 in h1 e n° 3-5-7-9-10-11-13-14-24 in h2). molte altre invece (più della metà) presentano pericolosità alta (n° 2-4-6-1219-20-21-22-23-27 in h3) e cinque molto alta (n° 1-1516-17-18-19 in h4). il metodo applicato sembra rispondere abbastanza bene all’esigenza di valutare la pericolosità relativa tra le conoidi esaminate e per definire quindi le zone a maggior rischio e pianificare la selezione degli apparati su cui eseguire studi più dettagliati, finalizzati alla progettazione di eventuali interventi di sistemazione. rimane il fatto però che questo metodo non consente di effettuare l’individuazione di zone a diverso grado di pericolosità all’interno di una singola conoide. ciò può essere trascurato quando le conoidi in oggetto sono di limitate dimensioni, ma può diventare un problema significativo, anche in termini amministrativi e di pianificazione, quando si ha a che fare con apparati grandi su cui insistono centri abitati o importanti infrastrutture. 13 tab. 6 matrici utilizzate per la valutazione della pericolosità alluvionale. da sanna (2003), parzialmente modificate. matrices used for the evaluation of the alluvial hazard. from sanna (2003), partly modified. valutazione della pericolosità alluvionale ... 14 n. santangelo, a. santo & p.i. faillace f ig . 7 c a rt a d e lla p e ri c o lo si tà d e lle c o n o id i d e l v a llo d i d ia n o . h 1 -h 2 -h 3 -h 4 = li ve lli d i p e ri c o lo si tà ( b a ss a , m o d e ra ta , a lt a , m o lt o a lt a ); r = s e tt o ri a r is c h io m o lt o e le va to . h az ar d m ap o f th e a llu vi al f an s o f th e v al lo d i d ia n o . h 1 -h 2 -h 3 -h 4 = c la ss e s o f h az ar d ( lo w , m o d e ra te , h ig h , ve ry h ig h ). r = s e c to rs o f th e f an s w it h v e ry h ig h r is k c o n d it io n s. per questo motivo sono stati ricercati altri parametri che consentissero di fare delle differenziazioni del grado di pericolosità all’interno di ogni singola conoide. sono stati allora considerati i profili topografici longitudinali delle conoidi studiate (fig. 8) costruiti considerando la direzione della bisettrice del cono stesso. e’ stato osservato che 15 conoidi su 27 presentano almeno una significativa rottura di pendenza che consente di individuare un settore apicale, più acclive, ed un settore distale caratterizzato da pendenze più blande. considerando che gli eventuali processi di trasporto solido più intensi (maggiore granulometria dei clasti) hanno minore probabilità di verificarsi nelle porzioni più distali delle conoidi, si è ritenuto opportuno ritoccare la classe di pericolosità precedentemente definita, utilizzando come elemento discriminante tra zone apicali e zone distali, la rottura di pendenza più significativa presente sulle conoidi in studio. in questo modo le parti distali dei conoidi n.° 1516-17-18 sono state declassate da una pericolosità h4 ad una h3 e quelle delle conoidi n.° 19-20-21-22-23 da h3 a h2. (fig. 7). 15valutazione della pericolosità alluvionale ... 2 la pendenza delle conoidi è stata calcolata come rapporto tra il dislivello e la distanza lineare; poiché essa non si mantiene costante lungo tutte le direttrici del cono, si è preferito calcolare diverse pendenze lungo due o più raggi del cono e ricavare la media dei valori ottenuti. tab. 7 risultati relativi alla valutazione della pericolosità per le 27 conoidi attive del vallo di diano. results of the evaluation of the alluvial hazard for the 27 active fans of the vallo di diano. conoidi massa tipologia del massa intensità pericolosità pericolosità pericolosità solida processo critica intrinseca opere 1 m2 t3 mc2 i2 p3 h4 molto alta 2 m2 t3 mc1 i1 p2 h3 alta 3 m2 t3 mc2 i1 p2 h2 moderata 4 m1 t2 mc1 i1 p2 h3 alta 5 m3 t2 mc1 i1 p2 h2 moderata 6 m1 t2 mc2 i2 p3 h3 alta 7 m1 t2 mc2 i1 p2 h2 moderata 8 m3 t2 mc2 i1 p2 h1 bassa 9 m3 t3 mc2 i1 p2 h2 moderata 10 m2 t3 mc1 i1 p2 h2 moderata 11 m3 t3 mc1 i1 p2 h2 moderata 12 m2 t3 mc1 i1 p2 h3 alta 13 m2 t3 mc1 i1 p2 h2 moderata 14 m3 t3 mc1 i1 p2 h2 moderata 15 m3 t3 mc2 i2 p3 h4 molto alta 16 m2 t3 mc2 i2 p3 h4 molto alta 17 m3 t3 mc2 i2 p3 h4 molto alta 18 m2 t3 mc2 i2 p3 h4 molto alta 19 m3 t3 mc1 i1 p2 h3 alta 20 m2 t3 mc2 i1 p2 h3 alta 21 m3 t3 mc1 i1 p2 h3 alta 22 m3 t3 mc1 i1 p2 h3 alta 23 m3 t3 mc1 i1 p2 h3 alta 24 m2 t3 mc2 i1 p2 h2 moderata 25 m3 t2 mc2 i1 p2 h1 bassa 26 m3 t3 mc2 i1 p2 h1 bassa 27 m3 t3 mc2 i1 p2 h3 alta per quanto riguarda le conoidi n° 8-25-26, nonostante esse siano state storicamente più volte interessate da eventi alluvionali, il basso grado di pericolosità ottenuto si spiega considerando le numerose opere idrauliche realizzate in alveo nell’ultimo decennio. 7. considerazioni conclusive lo studio condotto sulla pericolosità delle 27 conoidi alluvionali attive del vallo di diano ha voluto rappresentare un test metodologico che potrebbe essere applicato ed eventualmente modificato, in numerose altri settori pedemontani appenninici, per i quali non esistono ancora studi dettagliati. la metodologia adottata per il vallo, che deriva da quella proposta dall’autorità di bacino del po (sanna, 2003), ha dato buoni risultati e ripartito le 27 conoidi in almeno quattro diverse classi di pericolosità. per quanto riguarda le situazioni di maggior rischio non si è entrati nel merito di una precisa differenziazione delle classi (r1r4) in quanto questa non può prescindere dalla redazione di una carta del danno atteso che esula dalle competenze degli autori. sono state tuttavia indicate come zone a maggior livello di rischio (fig. 7) i settori apicali delle conoidi n° 15-16-1718 che interagiscono con il centro abitato di sala consilina ed i punti critici in cui possibili esondazioni potrebbero raggiungere la rete autostradale (conoidi n° 3-6-7-9). rimangono tuttavia numerosi altri settori ove conoidi a pericolosità h2 e h3 interagiscono con centri abitati, case sparse e strade provinciali e comunali. ad ogni modo le reali condizioni di rischio andrebbero verificate a scala di maggiore dettaglio (almeno 1:2000) con studi stratigrafici, geomorfologici ed idraulici che tengano conto soprattutto delle variazioni topografiche e morfologiche della conoide e, nei centri abitati, delle interazioni tra eventuali flussi idrici e assetto urbanistico locale, come ad esempio la presenza di alvei strada o di grandi strutture che possono modificare notevolmente la direzione di canalizzazione dei fenomeni di trasporto solido. bibliografia ascione a., cinque a., santangelo n. & tozzi m. (1992) il bacino del vallo di diano e la tettonica trascorrente plio-quaternaria: nuovi vincoli cronologici e cinematica studi geol. camerti, vol. spec. (1992/1), 201-208 blissenbach (1954) geology of alluvial fans in semiarid regions geological society of america bullettin, 65, 175-190. budetta p., santangelo n., santo a. (2000) interazioni tra processi alluvionali ed insediamenti abitativi in epoca storica: il caso della certosa di padula – convegno geoben 2000, torino 7-9 giugno. bull w.b.(1968) alluvial fans – journal of geology, 16, 101-106. d’aagostino v. (1996) analisi quantitativa e qualitativa del trasporto solido torrentizio nei bacini montani del trentino orientale estratto da: associazione italiana di ingegneria agraria 1° sezione, convegno di studio “i problemi dei grandi comprensori irrigui”, novara 6 – 7 giugno 1996. d e s c a l l y f e s a. a n d o w e n s i a n f. (2004) morphometric controls and geomorphic responses on fans in the southern alps, new zealand earth surface processes and landforms, 311-322 eckis r. (1928) alluvial fans in the cucamonga district, southern california – journal of geology, 36, 111141. genio civile (1858) busta 90, n° 91, archivio di stato di salerno giandotti m. (1934) previsione delle piene e delle magre dei corsi d’acqua memorie e studi idrografici, pubbl. 2 del servizio idrografico italiano, vol viii, 107. harvey a.m. (1988) controls of alluvial fan developments: the alluvial fans of the sierra de carrascoy, murcia, spain – catena supplement, 13, 123-137. jackson l.e.j.r., kostaschuk r.a, mac donald g.m. (1987) identification of debris flow hazard on alluvial fans in the canadian rocky mountains – geol. soc. of america, rew. in eng. geol., 7, 115-124. kostaschuk r.a., mac donald g.m., putman p.e.(1986) depositional processesand alluvial fan-drainage 16 fig. 8 alcuni esempi di profili topografici delle conoidi studiate, con indicazione delle principali rotture di pendenza. some exemplas of topographic profiles of the studied alluvial fan with indication of the main nick points. n. santangelo, a. santo & p.i. faillace basin morphometric relationship near banff, alberta, canada earth surface processes and landforms, 11, 471484. lippmann provansal m. (1987) l’apennin campanien meridional. etude geomorphologique. these de doctorat, universite d’aix-marseille, aix-en-provence, tome 1. marchi l.,pasuto a., tecca p.r. (1993) flow processes on alluvial fans in the eastern italian alps – z. geomorph. n.f., 4, 447-458. marchi l., tecca p.r. (1995) alluvial fans of eastern italian alps: morphometry and depositional processes geodinamica acta, 8 (1), pp. 20-27. melton m. a (1965) the geomorphic and paleoclimatic significance of alluvial deposits in southern arizona the journal of geology, 73, pp.1-39. national research council (nrc) (1996) alluvial fan flooding – national academy press, pp.1-131. pasuto a., marchi l., tecca p.r. (1992) tipologia del trasporto solido torrentizio su conoidi alluvionali nell’alto bacino dell’avisio (dolomiti) – boll. soc. geol. it., 111, pp.41-51. pesce c. (1889) il vallo di diano e la certosa di padula archivio di stato di salerno. ryder j. m. (1971a) some aspects of morphometry of paraglacial alluvial fans in south-central british columbia canadian journal of earth sciences, 8, pp. 1252-1264. sanna s. (2003) sistemazioni idraulico–forestali nella difesa del suolo pp. 331, dario flaccovio ed. santangelo n. (1991) evoluzione stratigrafica, geomorfologica e neotettonica di alcuni bacini lacustri del confine campano lucano (italia meridionale) tesi di dottorato di ricerca in ‘geologia del sedimentario’, iii ciclo, università degli studi di napoli “federico ii” dipartimento di scienzadella terra. 17 ms. ricevuto il 17 novembre 2005 testo definitivo ricevuto il 21 marzo 2006 ms. received:november 17, 2005 final text received:march 21, 2006 valutazione della pericolosità alluvionale ... imp.cannillo& map of the geological and geomorphological sites of the malfatano coast in sw sardinia: a contribution to the knowledge of the island’s geodiversity cataldo cannillo, felice di gregorio & antonio eltrudis dipartimento di scienze della terra università degli studi di cagliari laboratorio di geologia ambientale via trentino, 51 09127 cagliari – geoam@unica.it abstract: c. cannillo et al., map of the geological and geomorphological sites of the malfatano coast in sw sardinia: a contribution to the knowledge of the island’s geodiversity. (it issn 0394-3356, 2005). the area between cape malfatano and cape spartivento is emblematic of sardinia’s geology, especially with respect to the palaeozoic basement, whose lowermost part, the bithia formation (precambrian-lower cambrian?), crops out in this sector. compared to the tectonic setting typical of the outer zone of the sardinian segment of the south-european hercynian chain, this sector constitutes an anomaly, in which the metamorphism and deformation are more pronounced than in the sulcis-iglesiente region as a whole. another interesting feature of this area is the granitoid rock outcrop (cape spartivento orthogneiss) dated to the sardic phase of the middle ordovician that, elsewhere in the sardinian hercynian basement, is represented essentially by volcanic products. the geosites have been classified according to genetic processes (stratigraphic, metamorphic, magmatic, structural) whose importance has been evaluated on the basis of their being exemplary of geological evolution, of their chronostratigraphic, palaeoenvironmental and educational value. based on these criteria a number of geosites have been identified, where the following features can be observed: the cape spartivento orthogneiss, of special interest because of the effects created by intense hercynian deformation (penetrative schistosity with pronounced stretching lineation of the deformed crystals); the lithologic sequences of the bithia formation, with mylonitic and cataclastic bands, outcrops of stretched pebble metaconglomerate, again produced during hercynian deformation phases, and layers of metalimestone; the significant genetic, magmatic and lithologic aspects of hercynian granites; the intrusive relationships of the hercynian granitoid rocks with the metamorphic basement and of later dyke intrusions intersecting the contacts; ductile deformation structures in the hercynian basement with multiphase folding especially at the mesoscopic scale; brittle deformation structures sometimes with well exposed slickensides and slickenside striae; unconformity between the hercynian basement of the bithia formation and the conglomerate and eolianite deposits, evidence of ancient marine levels and palaeoclimates during the late pleistocene different to present day climates. the geomorphological sites identified in the area have been grouped together according to the genetic processes that created them (fluvial, meteoric, gravitational, littoral, eolian, etc.). on the map a symbol is used to denote the type of geomorphological site (point, linear or areal) defined according to its physical features and level of importance (local, regional, etc.). sites are numbered and a brief description is provided. the level of importance has been assigned according to the following evaluation criteria: exemplary of geomorphological evolution; palaeo-geomorphological evidence; educational value; scenic value. as for the geographical and physical features, the geomorphological forms in the malfatano area were created largely by littoral, eolian, fluvial, slope and gravitational processes, influenced by littoral processes. a number of areas have also been delineated on the map that stand out not so much for their specific forms but rather for their landscape qualities and geomorphological interest as a whole. these include the malfatano ria, a cove where the coastline is submerging, the bay of tuaredda and some tracts inland, the extension of the submarine relief, characterized by ridges, peaks, deep incisions and bizarre forms of erosion on meta-sandstone and meta-siltstone, granite and orthogneiss. the map of the geological and geomorphological sites described summarizes the results of a comprehensive investigation that entailed accurate small scale surveying and photointerpretation of the geoand geomorphic sites along the malfatano coast. a number of interesting examples have been identified that are evidence of the area’s significant geodiversity. riassunto: c. cannillo et al., carta dei geositi e geomorfositi della costa di capo malfatano nella sardegna sud-occidentale: un contributo alla conoscenza della geodiversità dell’isola. (it issn 0394-3356, 2005). l’area tra capo malfatano e capo spartivento rappresenta un settore emblematico della geologia della sardegna, soprattutto per quanto riguarda il basamento paleozoico, di cui affiora la parte basale, costituita dalla formazione di bithia (?precambriano-cambriano inf.). questo settore, infatti, costituisce un’anomalia nel quadro metamorfico-deformativo che caratterizza la zona esterna del segmento sardo della catena ercinica sud-europea, in quanto presenta un metamorfismo ed una deformazione più accentuati, rispetto a quelli della più ampia regione del sulcis-iglesiente. un altro aspetto che rende l’area particolarmente interessante è la presenza di affioramenti di rocce granitoidi (ortogneiss di capo spartivento) riferibili alla fase sarda dell’ordoviciano medio che, altrove, nel basamento ercinico della sardegna, manifesta essenzialmente prodotti vulcanici. la classificazione dei geositi è stata effettuata in base ai processi genetici (stratigrafico, metamorfico, magmatico, strutturale) nell’ambito dei quali si è operata una valutazione sulla base dell’esemplarità evolutiva geologica, dell’interesse cronostratigrafico, paleoambientale e dell’esemplarità didattica. in base a tali criteri è stato individuato un certo numero di geositi nei quali è possibile osservare: gli ortogneiss di capo spartivento, interessanti soprattutto per gli intensi effetti deformativi riconducibili alle fasi tettoniche erciniche (scistosità penetrativa con marcata lineazione di allungamento dei cristalli deformati); le sequenze litologiche della formazione di bithia, con fasce cataclastico milonitiche, affioramenti di metaconglomerati con fenomeni di allungamento di clasti, sempre per effetto delle fasi deformative erciniche e livelli di metacalcari; il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 257-266 258 c. cannillo et al. 1. introduction the purpose of this work is to illustrate the map of the geological and geomorphological sites of the malfatano coast in se sardinia. the map, which is one of the first examples of its kind on a large scale, has been drawn up using data gathered from accurate field observations and from photointerpretation which formed the basis for the identification, classification and evaluation of the different sites of geological and geomorphological interest. 2. geological-structural features of the hercynian basement in sardinia a complete section of the southern european hercynian chain crops out in sardinia (which forms its ancient basement) stretching from the outer zones in sw sardinia to the inner zones, cropping out in the ne of the island. the nw-se trending chain is characterized by shortening and by a tectonic-metamorphic zoning typical of orogenesis resulting from continental collision. the polarity of metamorphic rocks changes gradually from the anchizone in sw sardinia to the amphibolite facies in the ne, accompanied by an equally well-defined change in structural style. structurally the bedrock is characterized by sw striking hercynian thrust (carmignani et al., 1987), interposed between the metamorphic complex for the most part in the amphibolite facies of n sardinia and a highly deformed but essentially autochthonous outer zone with thrusts and folds that crop out in the sw of the island. in the outer zone, which crops out extensively in the iglesiente region, the pre-middle ordovician succession attests to the passage from a lower cambrian terrigenous shelf (bithia formation, nebida formation; cocozza, 1979) interbedded with basic-to-intermediate volcanic rocks likely associated with simultaneous rifting, to a lagoonal environment with oolitic bars (uppermost part of the nebida formation). the mostly terrigenous sediments of the nebida formation pass upwards into the thick carbonate sequence of the gonnesa formation, composed of tidal flat dolomites and limestones, broken up by extensional tectonics into basins and structurally high areas (rasetti, 1972; gandin et al., 1974; boni & cocozza, 1978; vai, 1982; cocozza & gandin, 1990). this formation is overlain by the cabitza formation that demarcates drowning of the carbonate shelf (gandin & pillola, 1985; cocozza & gandin, 1990). 3 the outcropping palaeozoic basement of malfatano area 3.1 bithia formation the most extensive part of the study area is composed of a succession of metamorphic rocks belonging to the bithia formation that crops out in the sw tip of the island along a narrow belt girding the cape spartivento orthogneiss. because of intense tectonization, the actual thickness of this formation is uncertain though apparent thickness is more than 600 m. this is a siliclastic succession composed largely of phyllite, metaquartz arenite and metasandstone interbedded with metaconglomerate and marble. outcrops of metaconglomerate up to a few metres thick are located near to the coast between punta de s’ega de su tramatzu and cala de su senzu, originally poorly sorted polygenic conglomerate. the gli aspetti significativi degli affioramenti di graniti ercinici, genetici magmatici e litologici; i rapporti intrusivi dei granitoidi ercinici con il basamento metamorfico e quelle delle successive intrusioni di corpi filoniani che ne intersecano i contatti; le strutture deformative duttili nel basamento ercinico, presenti con pieghe polifasiche soprattutto alla scala mesoscopica; le strutture deformative fragili presenti talora con specchi di faglia ben esposti e relative strie; la discordanza tra basamento ercinico della formazione di bithia e depositi conglomeratici ed eolianitici che testimoniano antichi livelli marini e paleoclimi del pleistocene superiore differenti da quelli attuali. i geomorfositi rilevati nell’area sono stati raggruppati sulla base del processo genetico che ha determinato la loro formazione (fluviale, meteorico, gravitativo, litorale, eolico, ecc.). ciascun geomorfosito è indicato sulla carta da un simbolo che identifica il tipo (puntuale, lineare o areale) in funzione delle caratteristiche fisiche, ed il livello di importanza (locale, regionale, ecc.). un numero di identificazione rimanda ad una specifica descrizione sintetica. il livello di importanza è stato definito in base ai seguenti criteri di valutazione: esemplarità evolutiva geomorfologica (processi); testimonianza paleo-geomorfologica; esemplarità didattica (forme); valenza scenica. in relazione alle caratteristiche geografico-fisiche, nell’area prevalgono numericamente i geomorfositi ricondicibili a processi litorali, eolici, fluviali e di versante, gravitativi con influenza di processi litorali. nella carta sono state anche delimitate alcune aree che si distinguono non tanto per le specifiche forme presenti, quanto per il loro interesse paesaggistico e geomorfologico d’insieme. tra queste, la ria di malfatano, insenatura testimoniante l’evoluzione di una costa di sommersione, la baia di tuaredda e alcuni tratti dell’entroterra caratterizzati dall’evoluzione subaerea del rilievo, con crinali, culminazioni, incisioni vallive e peculiari su metarenarie e metasiltiti, graniti e ortogneiss. la carta dei geositi e dei geomorfositi rappresenta la principale sintesi grafica di un’analisi integrata condotta tramite accurati rilevamenti di dettaglio e fotointerpretazione dei geositi e dei geomorfositi dell’area costiera di malfatano, ove sono stati riscontrati interessanti elementi che ne documentano una elevata geodiversità. keywords: geosites, geomorphosites, geodiversity, malfatano coast, south sardinia. parole chiave: geositi, geomorfositi, geodiversità, costa di malfatano, sardegna meridionale. highly deformed clasts, embedded in an arenite quartzfeldspar matrix, are composed mostly of fragments of grey and black (lydite) quartzite from vein quartz. outcrops of pale grey marble are scattered throughout the area. these range from the metre-thick layers near sa bidda beccia, monte corilla, p.ta de isurderas to 15-20 m thickness at cape malfatano. the bithia formation is interpreted as a regressive trend terrigenous succession that formed on a continental margin (junker & schneider, 1983; gandin, 1987; gandin et al., 1987). a very low grade, upward decreasing (junker & schneider, 1983) hercynian metamorphism has been described for this formation (palmerini & palmerini sitzia, 1978). based on its stratigraphic position beneath the infracambrian nebida formation (junker & schneider, 1979; minzoni, 1981; carannante et al., 1984), and on the correlations with precambrian formations elsewhere in europe, the bithia formation has been dated to the upper precambrian (cocozza, 1979). a tentative precambrian age has also been reported based on a few poorly preserved acritarchs (pittau demelia & del rio, 1982), though the echinoderm plates discovered within the interbedded carbonate rocks also suggests a lower cambrian age (gandin, 1987). on the whole, the main schistosity of the bithia formation forms a dome (cape spartivento dome) with a radius of roughly 10 km and gently north-dipping axis. in the middle of this dome-like structure the more strongly metamorphosed complex crops out. carmignani et al. (1994) interpret the dome at cape spartivento as the metamorphic core complex which formed following a major deformation phase associated with the crustal thickening resulting from tectonic shortening during the hercynian, which occurred in the rest of the outer zone. 3.2 cape spartivento orthogneiss the orthogneiss crops out near to cape spartivento and tuaredda, and is also referred to in the literature as “monte filau orthogneiss”. these orthoderivatives in amphibolite facies of granitoids, dated to the ordovician magmatism that affected the whole island, were transformed into orthogneiss by the hercynian tectonic-metamorphic event as the radiometric age of 280 ma determined for the biotite indicates. the u-pb zircon age of 478±16 ma for the orthogneiss (delaperrière & lancelot, 1989; 449 ma: ludwig & turi, 1989), dates these magmatites to the ordovician. the orthogneiss complex at cape spartivento intrudes into the m. settiballas schists and is tectonically related with the overlying bithia formation (sassi & visonà, 1989; sassi, 1990). the gneiss formation is composed largely of medium-to-coarse grained orthogneiss having a schisty-augen texture in which the quartz and k-feldspar phenocrystals, with grain size normally over 1 cm, are oriented in the same direction and embedded in phylosilicates (biotite and to a lesser degree muscovite). centimetre-to-metre size fine-grained banded aplitic gneisses (original dykes) also occur within the orthogneiss. these contain fusiform blackish andalusite aggregates that give rise to a pronounced stretching lineation and blastomylonitic and cataclastic gneiss. the latter forms the outermost portions of the gneiss 259map of the geological ... body, in direct contact with the overlying bithia formation. the cape spartivento orthogneisses crop out regularly throughout the central-eastern part of the study area and in a few isolated outcrops, including those near to the padiglioni islet. 3.3 hercynian magmatism the hercynian magmatism is represented both by intrusive rocks and dyke complexes. the intrusive rocks are essentially granodioritic and leucogranitic in composition, the former cropping out in the southern part of capo spartivento, the latter in the northern part. the sub-vertical chiefly nw-se trending dyke complex, which intrudes the metamorphic basement and the hercynian granitoid rocks, is composed of sporadic quartz, rhyolite and andesite-basalt dykes. 4. quaternary deposits the oldest outcrops of quaternary deposits in the area are dated to the upper pleistocene and are represented by the “ancient alluvia” and marine-littoral sediments. the predominantly alluvial cone/plain fluvial sediments consist of more or less compacted conglomerate, gravel and sand often with abundant reddish silty-clay matrix. in the areas comprised between the hills and the small coastal plains these deposits are reincised and terraced. this coarse clastic material contains angular or slightly rounded on average centimetre to decimetre sized clasts within an abundant reddish clayey-ferruginous matrix. they are believed to have been deposited in wet and cold climatic conditions by glacial runoff during the pleistocene. on the pediment (or erosion glacis) developed mostly on palaeozoic crystalline rocks, these debris aprons are fairly discontinuous and thin (from a few decimetres to a few metres thick). locally, in the most sheltered coves, marine-littoral sediments of the tyrrhenian have deposited directly on the palaeozoic basement, generally perched up to 3-4 m above the actual sea level (“strombus-containing tyrrhenian bench” auct.) (vardabasso, 1956; ulzega & ozer, 1982), composed of conglomerate and calcareous cemented sandstone and biocalcarenite, generally containing a warm sea fossil association of lamellibranchs, gastropods, coelenterates, algae. the tyrrhenian marine deposits were followed by a regressive phase represented by eolian würmian sediments with interbedded palaeosoils. outcrops of fossil dunes of würmian age occur especially in proximity of cape malfatano and around the piscinnì tower, where there is interesting and clear evidence of an ancient roman quarry. numerous blocks of these hardened dunes were removed in roman times. holocene deposits consist above all of valley floor and alluvial plain gravel-sand deposits, of beach sands and gravels, of backbeach eolian sands (tuaredda cove), in some places with dune formations extending a few kilometres inland, and of the silty-clayey deposits of the malfatano lagoon. the angular detritus and more or less coarse detritus deposits at the foot of the steepest slopes can also be dated to the holocene. 260 5. geomorphological features the topography of the study area, along the coastal belt and inland, is hilly to mountainous, though of moderate elevation, below 400 m. however energy levels are fairly high on account of the alternation of mountainous/hilly areas with fluvial incisions, in some places narrow and deep with steep rocky slopes, in others taking the form of broad valleys or ledges with almost flat or gently sloping bottom. some of these valleys taper into the sea and in the coastal belt often give way to marshland and lagoons (stagni di pianu spartivento, stagno di piscinnì) bounded seawards by littoral ridges bordering small beaches and sand dunes. the terrain is extremely varied, featuring rocky headlands (e.g. capo malfatano and schiena del siciliano), wide bays and small coves with sandy and pebbly beaches, some with islets of various sizes a short distance from the shore. the drainage pattern is prevalently sub-dendritic and/or centripetal, locally angular where it follows the existing tectonic lines. the streams are small and ephemeral. the main geomorphological structure in the area is the roughly n-s trending flat-bottomed valley depression (malfatano), a little over 1 km wide, which stretches for 4 km down towards the sea into a deep cove forming the natural porto di malfatano harbour. this a classic example of a drowned river valley, the most magnificent on the south coast of sardinia, that was created by the submergence of a pre-existing river eroded valley during the versilian transgression. the inner edge of the cove, which is sheltered from the direct action of wave motion, will eventually be filled in by the gradual deposition of silty-sandy sediments at the land/sea interface. the malfatano coastal belt displays submerged coast features, moulded by subaerial fluvial sediments. in particular, the porto di malfatano is a ria, the lower portion of a palaeo-river valley that was drowned during the versilian transgression. the geomorphosites identified in the study area have been grouped together by the dominant process involved in their formation (fluvial/wash, atmospheric agents, gravitational, littoral, eolian), each group with a different colour. their degree of importance has been determined on the basis of the following evaluation criteria : exemplary of geomorphological evolution (processes); palaeo-geomorphological evidence; educational value (shapes); scenic value. with regard to the physical/geographic features of the study area, the most numerous geomorphosites are those formed by littoral processes namely beaches (including the well known tuarredda beach), islets and stretches of cliffs. the extensive malfatano ria, bears witness to the evolution of a submerged coast. a number of small dune bars of significant geomorphological interest have been chosen to represent the eolian process, though in terms of morphological evolution and landscape, these could be included in the littoral processes. the geomorphosites formed by fluvial/wash processes are represented by entrenched valleys or river gorges, most of which are found inland, as well as forms of selective erosion represented by an outcropping dyke and a typical cone-shaped hill. landforms moulded by atmospheric agents include examples of rock domes, rugged shapes created by rock piles and of honeycombed rocks sculpted by cavernous weathering. only one form of gravitational process is included in the map, represented by a rockfall from the capo malfatano cliffs, a fine example of the evolution of gravitational phenomena in a sheer rocky coast. 6. conclusions: the geosites and geomorphosites map in the light of the above considerations, the segment comprised between cape malfatano and cape spartivento can be regarded as emblematic of sardinia’s geology, especially as concerns the palaeozoic basement whose lowermost part, the bithia formation (?precambrian-lower cambrian) crops out here. in fact within the overall metamorphism/deformation context of the outer zone of the sardinian segment of the south-european hercynian chain, this area is atypical insofar as the metamorphism and deformation are more pronounced than in the sulcis-iglesiente region, of which it is a part. another distinctive and geologically interesting feature of this area is the occurrence of granitoid rock outcrops (cape spartivento orthogneiss) dated to the sardic phase of the middle ordovician which elsewhere in the sardinian hercynian basement is represented largely by volcanic products. the geological sites were identified, classified and evaluated according to the method proposed by barca & di gregorio (1991a), brancucci & d’andrea m. (2002), panizza m. & piacente s. (2002), which considers genetic characteristics (stratigraphic, metamorphic, magmatic, structural). their importance has been evaluated on the basis of their being exemplary of geological/structural evolution, of their chronostratigraphic, palaeoenvironmental and educational value. nineteen geosites (tab. 1) have been identified having the following distinctive genetic features: the cape spartivento orthogneisses, of special interest because of their uniqueness in the regional geological context and the intense deformation effects produced during hercynian tectonic activity (penetrative schistosity with pronounced stretching lineation of the deformed crystals). though the provincial malfatano road 71 cuts across the orthogneiss, near the sa tuaredda nuraghe, the outcrops are relatively inaccessible by road or foot, given the topography of the landscape. because of their geological rarity in sardinia, the geosites have also been chosen according to their accessibility (the road cut near the sa tuaredda nuraghe, the coast around padiglioni islet, the ridge near punta padenti); the lithological sequences of the bithia formation (clearly visible along the hairpin bends of the provincial malfatano road 71), with cataclastic/mylonitic bands, metaconglomerate outcrops near the coast between punta de s’ega de su tramatzu and cala de su senzu, stretched pebbles, again the effect of the c. cannillo et al. 261map of the geological ... tab.1 geosites in the malfatano area and relative parameters of evaluation. geositi nell’area di malfatano e relativi parametri di valutazione. features evaluation genetic process description 1 lens-shaped interbedded metalimestone of the • • • •bithia formation 2 upper pleistocene beach deposits evidence of • • • •ancient marine level 3 unconformity between eolinites of the upper • • • •pleistocene and metamorphic basement 4 contact between hercynian metamorphic rocks, • • •granitoids and dykes 5 metaconglomerate of the bithia formation with • •metasandstone, quarzite and lydite. 6 cape spartivento orthogneiss • • • 7 well exposed stratigraphic succession of the • •bithia formation 8 cape spartivento orthogneiss with well exposed and clearly visibile hercynian metamorphic and • • • deformation features 9 well-exposed hercynian granodiorite outcrops: mineralogic, textural and structural features • • clearly visible 10 well-exposed hercynian leucogranite rock outcrops: mineralogic, textural and structural • • • features clearly visible 11 sub-vertical basic dyke in the metamorphic rocks •of the bithia formation 12 sub-vertical, nw-se trending, outcropping granitic dyke, prominent feature of the landscape, • •intruded between metamorphic rocks of the bithia formation and hercynian leucogranites. 13 sub-vertical, nw-se trending, outcropping quartz dyke, prominent feature of the landscape • • intruding the cape spartivento orthogneisses 14 well visible, steeply dipping, ne-sw trending • •granitic dyke intruding the hercynian leucogranites. 15 fold structures in the metalimestones of the • •bithia formation. 16 slickenside showing transcurrent movement • 17 schistosity and stretching lineations in the cape •spartivento orthogneiss 18 strongly deformed clasts in the bithia formation • •metaconglomerate 19 hercynian late folds in the metasandstone of the • •bithia formation e xe m p la ry o f g e o lo g ic a lst ru c tu ra l e vo lu ti o n c h ro n o st ra ti g ra p h ic e vi d e n c e p a la e o e n vi ro n m e n ta l e vi d e n c e e d u c a ti o n a l v a lu e s tr a ti g ra p h ic a n d m e ta m o rp h ic m a g m a ti c m a g m a ti c p o in t l in e a r a re a l deformation phases during the hercynian, and layers of metalimestone, the major outcrops occurring near the cape malfatano tower; the significant genetic, magmatic and lithological features of the hercynian granite rocks; the intrusive relationships of the hercynian granitoid rocks with the metamorphic basement and of later dyke intrusions intersecting their contacts (well exposed in the cliffs near the cape spartivento lighthouse); ductile deformation structures in the hercynian basement with multiphase folding especially at the mesoscopic scale (visible along the hairpin bends of the provincial malfatano road n.71); brittle deformation structures sometimes with well exposed slickensides and slickenside striae (a well preserved example can be seen along the path north 262 of mount sa guardia manna); unconformity between the hercynian basement of the bithia formation and the conglomerate and eolianite deposits, evidence of ancient marine levels and palaeoclimates during the late pleistocene different from present day climates (well exposed near the piscinnì tower). in geomorphological terms, particularly significant are the landforms associated with littoral processes (high rocky coasts, coasts indented with deep inlets, beaches nestled in coves, tiny islets and rugged cliffs, etc.), landforms associated with fluvial and slope processes and those produced by weathering. the geomorphological sites surveyed in the area were identified, classified and evaluated following the method proposed by barca & di gregorio (1991b) and barca et al. (1992) based on the genetic process responsible for their formation (fluvial, meteoric, gravitational, littoral, eolian, etc.). each geomorphological site is denoted on the map with a symbol that identifies its features (point, linear or areal) and level of importance (local, regional, etc.) according to a measure of its importance at the geographic scale (barca & di gregorio, 1999; bertacchini et al. 2002b). the sites are numbered and brief specific description is provided. the level of importance has been determined adopting the following evaluation criteria: exemplary of geomorphological evolution (processes); palaeo-geomorphological evidence; education value; scenic value. with regard to the geographical-physical features (tab. 2), the geomorphological sites shaped by littoral processes are by far the most numerous (9) followed by c. cannillo et al. tab. 2 geomorphological sites in the malfatano area and relative parameters of evaluation. siti geomorfologici nell’area di malfatano e relativi parametri di valutazione. features evaluation genetic process description 1 dyke outcropping near the sulcitana state road • • • •195 2 furradroxiu addis ravine • • • 3 cone-topped hill with elongated base near riu • • •perdosu nuraghe 5 dyke outcropping in perda longa area • • • • 4 fluvial valley enclosed northwards by mount • •de sa fossa 6 rio perdosu enclosed fluvial valley • • • • 7 relic forms of meteoric erosion near arcu • •bacca tidoru 8 monte corilla granitoid dome • • 9 rocca di corilla granitoid dome • • 10 honeycombed metamorphic rocks in the luas area. • • 11 tafoni features and relic forms of meteoric erosion • • •in the granite rocks at sa guardia manna 12 rockslide with influence of littoral processes •near the cape malfatano tower 13 tuarredda cuspate beach • • • • 14 cala antoni areddu beach with backbeach dunes • • • • 15 pebbly beach facing ferraglione islet • • 16 tuaredda islet and bay • • • • 17 ferraglione islet • • • 18 padiglioni islet • • • 19 cape spartivento cliffs • • 20 cape malfatano cliffs • • 21 malfatano ria and lagoon • • • • 22 dunes on tuarredda beach • • e xe m p la ry o f g e o m o rp h ic e vo lu ti o n p a la e o g e o m o rp h ic e vi d e n c e e d u c a ti o n a l v a lu e s c e n ic v a lu e f lu vi a l w a sh l it to ra l m e te o ri c p o in t l in e a r a re a l gravitational eolic 263map of the geological ... fig. 1 geosites and geomorphosites map of the capo malfatano coast and relative level of interest. carta dei geositi e geomorfositi della costa di capo malfatano e il relativo livello di interesse. fluvial (6), eolian (1) and gravitational influenced by littoral processes (1). the geosites and geomorphosites identified in the study area, which bear testament to its great geodiversity, have been mapped in the 1:10.000 scale coloured map of geosites and geomorphosites of the malfatano area (se sardinia), the main product, in graphic terms, of the research project concerned with here. the map provides a fundamental tool for land planning and for environmental impact assessment of man-made works as well as for enhancing the value of the area for public enjoyment and educational purposes. the 1:10.000 map of geosites and geomorphological sites summarized in fig. 2, is a concise graphical representation of an analysis conducted by means of accurate and detailed field surveys combined with photo-interpretation of the malfatano coast. some interesting features have been identified that bear witness to the geodiversity of the area (bertacchini m. et al.,1999; carton et al. 2003; piacente & poli, 2003). the educational and tourist-cultural value of these geosites and geomorphological sites is as yet little appreciated and suitable measures are required for conserving and enhancing the geologic-geomorphic heritage. a number of areas have also been delineated in the map, which provides a valuable tool for geotourism and geoconservation (maciocco, 1988; poli & bini, 2002), that stand out not so much for their specific landforms but rather for their landscape qualities and geomorphic interest as a whole. these include the malfatano ria, a cove that is testament to the evolution of the submerging coastline, the bay of tuaredda, with its breathtaking landscape as well as some inland areas that are the extension of the submarine morphology, characterized by ridges, peaks, deep incisions and bizarre forms of erosion on meta-sandstone and metasiltstone, granites and orthogneiss. acknowledgements work conducted within the framework of the research project for setting up an experimental laboratory for the geoenvironmental analysis and monitoring of the malfatano coastal belt, by the environmental geology and thermographic laboratory at the department of earth sciences, university of cagliari (responsible scientist. prof. f. di gregorio) on behalf of forma urbis s.p.a. and national research project “i geomorfositi nel paesaggio italiano”, national co-ordinator prof. sandra piacente). references barca s. & di gregorio f. 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(2002) geositi nel paesaggio italiano: ricerca, valutazione e valorizzazione. un progetto di ricerca per una nuova cultura geologica geologia dell’ambiente, vol. 2/2002, pp.3-4. pittau demelia p. & del rio m. (1982) acritarchi e loro significato stratigrafico nelle successioni paleozoiche della sardegna in: l. carmignani, t. cocozza, c. ghezzo, p.c. pertusati & c.a. ricci (eds.), guida alla geologia del paleozoico sardo. guide geologiche regionali, società geologica italiana: pp. 33-35. poli g. (eds.) 1999 geositi, testimoni del tempo. regione emilia-romagna, bologna, p.259. poli g. & bini m. (2002) geositi un laboratorio di comunicazione e valorizzazione. in: atti del convegno “la geologia ambientale: strategie per il nuovo millennio”, genova 27 – 29 giugno 2002. rasetti f. (1972) cambrian trilobite faunas of sardinia atti acc. naz. lincei, mem. cl. sc. fis. mat. e nat.: 11, pp. 1-100. sassi f.p. (1990) caratterizzazione petrografica delle formazioni di nebida e di bithia nel sulcis, con particolare riguardo alla fascia limite ente minerario sardo, relazione inedita, cagliari, 38 pp. sassi f.p., mazzoli c., sassi r. & visonà d. (1990) the capo spartivento-m. filau puzzle and structure of sw sardinia plinius: 3, milano. sassi f.p. & visonà d. (1989) gli gneiss di monte filau ed i loro rapporti con le rocce circostanti progemisa s.p.a. (relazione inedita), cagliari, 38 pp. tucci p. (1983) le metamorfiti dinamometamorfiche di capo malfatano (sulcis, sardegna) period. min.: 52, pp. 149-176. 265map of the geological ... ulzega a. (1995) geomorphology and stratigraphy of late quaternary in: a. cherchi (ed.), 6th paleobenthos international symposium, guidebook, cagliari, october 25-31, rend. sem. fac. sc. univ. cagliari (suppl. vol. 65, 1995): pp. 11-24. ulzega a. & ozer a. (1982) comptes-rendus de l'excursion-table ronde sur le tyrrhénien de sardaigne inqua: pp. 1-87. vai g.b. (1982) fasi di "rifting", nuovi dati stratigrafici e conseguenze paleogeografiche nel paleozoico inferiore in: l. carmignani, t. cocozza, c. ghezzo, p.c. pertusati & c.a. ricci (eds.), guida alla geologia del paleozoico sardo, società geologica italiana, guide geologiche regionali, pp. 93-195. vardabasso s. (1956) il quaternario della sardegna atti iv congr. int. quaternario, roma-pisa 1953, pp. 995-1018. zarlenga f. (1996) i geotopi, dalla ricerca scientifica alla pianificazione, controllo e gestione geologia dell’ambiente, vol. 4,2, pp. 3-6. 266 c. cannillo et al. imp.boano& pleistocene deformation of the collina di torino inferred from the modelling of their fluvial succession paola boano1, m. gabriella forno2 & stefania lucchesi3 1libero professionista, via asti 13, tonco (at) 2dipartimento di scienze della terra, università di torino 3c.n.r. istituto di geoscienze e georisorse, sez. di torino abstract: boano p., forno g., lucchesi s., pleistocene deformation of the collina di torino inferred from the modelling of their fluvial succession. (it issn 0394-3356, 2004). the modelling of the po plain adjoining the collina di torino by alpine watercourses, now tributaries of the po, is evidence of the extremely recent setting of the present river po. suspended traces of an earlier collector have been preserved on the western and north-western slopes of the collina di torino, where remains of a terraced succession of surfaces with local fluvial deposits can be find out along the present watersheds. differentiation and correlation of the individual surfaces according to their elevation and the alteration degree of their sediments has provided a chronological record of the middle pleistocene-holocene. this succession is the result of the progressive deformation of the distal sectors of the alpine fans involved in the uplift of the collina di torino, which has resulted in deep erosion of the ancient hydrographic pattern as shown by the scarps tens of metres high between the surfaces. it may be supposed that the progressive uplift of the relief and the nw migration of their outer edge brought initially flat areas into the relief and led to a differential deformation of ancient relief forms and deposits of different ages. comparison between the chronology of these surfaces and their distribution within an approximately 400-metres difference of level shows that the rate of uplift from the middle pleistocene to the holocene was of the order of 1mm/yr riassunto: boano p., forno g., lucchesi s., deformazione pleistocenica della collina di torino dedotta dal modellamento della successione fluviale. (it issn 0394-3356, 2004). il modellamento del tratto di pianura padana antistante la collina di torino da parte dei corsi d’acqua alpini, attuali affluenti del f. po, consente di ipotizzare l’impostazione estremamente recente del collettore principale nella pianura piemontese. le tracce di un precedente collettore risultano invece conservate, sensibilmente sospese, sui versanti occidentale e nordoccidentale del rilievo collinare. in questi settori sono osservabili, sulla sommità delle attuali dorsali spartiacque, i relitti di una successione di forme fluviali pianeggianti, a cui sono localmente associati depositi fluviali: i diversi lembi sono stati distinti tra loro e correlati in base alla differente quota e alla diversa alterazione dei sedimenti, consentendo un riferimento cronologico complessivo all’intervallo di tempo compreso tra il pleistocene medio e l’olocene. la successione terrazzata in esame è connessa alla progressiva deformazione del settore distale dei conoidi alpini, coinvolti nel sollevamento della collina di torino: tale deformazione ha comportato un sensibile approfondimento erosionale dell'antico reticolato idrografico evidenziato dal modellamento delle scarpate, con altezza di alcune decine di metri, che separano i diversi lembi terrazzati. il progressivo sollevamento dell’area collinare e la migrazione verso nw del suo margine esterno avrebbero determinato l’inglobamento nel rilievo di aree inizialmente pianeggiati e la deformazione differenziale delle forme e dei depositi riferibili ai diversi intervalli di tempo. in particolare, confrontando il riferimento cronologico dei diversi elementi morfologici e dei sedimenti ad essi associati con la loro distribuzione altimetrica e quindi con il dislivello di circa 400 m che essi presentano, è possibile stimare che tra il pleistocene medio e l’olocene si sia verificato un sollevamento con tasso medio di circa 1 mm/anno. key words: collina di torino, fluvial sediments, deformation, pleistocene. parole chiave: collina di torino, depositi fluviali, deformazione, pleistocene. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 145-150 the terraced fluvial succession previous studies the collina di torino forms a relief that rises to an altitude of some 700 m, 500 m above the adjacent po plain (figs. 1-2). in geological terms, the collina di torino is composed of a succession of eocene to pliocene terrigenous marine sediments that rests on an alpine substratum and has been involved in the apennine deformation. the relief is separated from the plain by buried tectonic structures known as the "padan thrust" (piana & polino, 1994) (fig. 3). the relief and the plain beside it had a different geodynamic evolution: it corresponds for the collina di torino to a marked uplift during the plio-quaternary and for the plain to a moderate lowering in early pliocene and weak to moderate uplift in the middle and late pliocene and quaternary (carraro et al., 1987). the different evolution of these two areas is responsible for considerable changes in the hydrographic pattern during the quaternary. in particular the absence of the po sediments in the present po plain and the wide distribution of the left tributaries sediments point out the absence of this collector during most of the pleistocene (carraro, 1976). on the other hand on the southern slope of the relief and in the adjacent altopiano di poirino are preserved remains of a middle upper pleistocene watercourse with a high discharge (a in fig. 2): this evidence can be ascribed to a previous course of the po river and suggests a deformation of 146 p. boano, m.g. forno & s. lucchesi the area (forno, 1980; 1982; compagnoni & forno, 1992). furthermore, recent preliminary studies on the morphology of the western slope of the relief reveal a middle-upper pleistocene terraced succession of fluvial surfaces with a broad altimetric distribution connected with the deformation of the relief (boano & forno, 1997). this succession suggests the modelling of the western slope by important ancient watercourses (b in fig. 2). locally, on the villa gualino surface, some boreholes have disclosed the discontinuous conservation of lenses of sandy-silty fluvial deposits unconformable with the marine substratum. the results obtained indicate that the succession was shaped by one or more collectors that conveyed the northern alpine rivers, especially with the contribution of the dora riparia (forno et al., 2002). aim of the work and new data the aim of the work is to carry out a geological study of forms and deposits of the terraced succession of the western slope of the collina di torino, to extend the research to the north-western slope and to find a preliminary reconstruction of the recent deformation of the area. difficulties were encountered owing to the loess cover (forno, 1979) and because the area is extensively built up and shows local anthropic modifications. however it was found that the modifications thus introduced are generally confined to the widening of existing surfaces and have not led to the creation of man made surfaces. surveys carried out in the present preliminary study have shown that both slopes carry the remains of a terraced succession of fluvial surfaces modelled in either the tertiary substratum or in a thin cover of fluvial sediments and separated by scarps some tens of metres high (fig. 4). these surfaces are distributed on the western and the north-western slopes in the secondary ridges separating the present valleys. each fluvial surface covers an area of 5,000 200,000 m2; they are widespread at different altitudes between 630 and 240 m a.s.l. and mostly have a n-s or ne-sw trend, parallel to the main watershed. their morphology and distribution have thus no link with the current w or nw drainage fig. 1 geographical location of the collina di torino. inquadramento geografico della collina di torino. fig. 2 former trend of the po river to the south of the collina di torino (a); former path of the watercourse that modelled the terraced succession on the western slope (b). antico percorso del f. po a sud della collina di torino (a); antico andamento del corso d'acqua responsabile del modellamento della successione terrazzata del versante occidentale (b). fig. 3 structural diagram of the piedmont hill reliefs: the northern boundary of the collina di torino is represented by the “padan thrust front” (ptf). legend: a) buried overthrusts; b) strike slip faults; c) anticlinal axes (modified from piana & polino, 1994). the square represents the studied area. schema strutturale dei rilievi collinari piemontesi: il margine settentrionale della collina di torino è delimitato dal “thrust padano” (ptf). legenda: a) sovrascorrimenti sepolti; b) faglie trascorrenti; c) assi di anticlinali (modificato da piana & polino, 1994). il riquadro rappresenta l’area in esame. 147pleistocene deformation of the collina di torino ... fig. 4 transverse cross-section of the western and north-western slopes of the collina di torino (height scale exaggerated). the surfaces are numbered from the most recent and in the upper altimetric sector differentiated between the two slopes (w for the western slope and n for the north-western one). for each surface is shown the most significant toponym together with its altitude and munsell soil colour value. profili trasversali dei versanti occidentale e nordoccidentale della collina di torino, con scala delle altezze esagerata. le diverse superfici sono numerate a partire dalla più recente e differenziate tra i due versanti nella fascia altimetrica superiore (w per il versante occidentale e n per quello nordoccidentale): per ognuna sono precisati il toponimo più significativo, lo sviluppo altimetrico e l’indice di colore del suolo che le caratterizza. fig. 5 simplified longitudinal profile of the terraced succession of the western and north-western slopes. a and b are the upper and lower altimetric sectors. the dashed line indicates a former watershed between the two slopes. the arrows show the drainage direction of the stream net that modelled the succession. surfaces are indicated as in fig. 4. profilo longitudinale semplificato della successione di forme terrazzate dei versanti occidentale e nordoccidentale della collina di torino nelle fasce altimetriche a e b. la linea tratteggiata indica la presenza di un precedente spartiacque tra i due versanti; le frecce indicano la direzione di drenaggio del reticolato idrografico responsabile del modellamento. per le diverse superfici sono indicati gli stessi riferimenti di fig. 4. 148 pattern but are connected with the modelling by ancient watercourses during the uplift of the relief. the surfaces clearly differ in function of their altitude. those at high levels are considerably deformed, and have been remodelled, dissected and mostly deprived of their original fluvial deposits, whereas those located at the lower altitudes are less deformed, more continuous, better preserved, and most have retained their deposits. there is also a difference between the two slopes. the north-western slope displays extensifig. 6 progressive evolution of the stream net that modelled the succession. in the upper altimetric sector (a) there are two watercourses draining in opposite directions, in the lower sector (b) there is only one. the dotted line shows the principal current watershed. the hatched area indicates the former watershed between the two sectors. surfaces are indicated as in fig. 4. evoluzione progressiva del reticolato idrografico responsabile del modellamento della successione terrazzata collinare: nelle fasce altimetriche superiori (a) è rappresentato l’andamento di due corsi d’acqua drenanti in direzione opposta, in quelle inferiori (b) è indicato lo sviluppo di un corso d'acqua unico. la linea tratteggiata rappresenta l’attuale spartiacque principale; l’area tratteggiata corrisponde al precedente settore spartiacque tra i due versanti in esame. per le diverse superfici sono indicati gli stessi riferimenti numerici di fig. 4. p. boano, m.g. forno & s. lucchesi 149 ve terraces, all inclined to the ne, whereas the western slope shows a greater variety of forms corresponding to wide meanders and smaller surfaces inclined in opposite directions (north and south). the altimetric distribution of the terraces on the two slopes is also different (figs. 4 5). the fluvial deposits, where visible, form lenses some metres thick with a clear erosional base. they mainly consist of an unstratified sandy-silty succession, whereas gravelly sediments appear only locally, particularly in the remains of meanders. the pedogenetic evolution of sediments gradually decreases towards the lower surfaces. the munsell colour index of the soils on the substratum and on fluvial deposits ranges from 2.5 yr to 10 yr (figs. 4 5). mapping of the terraces has been followed by their correlation, account being taken of possible changes in the original altimetric setting due to erosion by run-off waters and tectonic deformation. two criteria were used: the pedostratigraphic criterion for the deposits, and the altimetric criterion for the erosional surfaces supporting the fluvial lenses. they both show that there is a clear correlation between the lower terraced surfaces of the two slopes (b in figs. 5-6), but none between the upper surfaces (a in figs. 5 6). conclusions the quaternary evolution of the western and north-western slopes of the collina di torino can be preliminarly deduced from data collected in this study. the preferential n-s and ne-sw trend of the terraces parallel to the main watershed and the fact that their distribution differs from that of the present watercourses suggest that they were shaped by a markedly different hydrographic pattern. although the distribution of the succession is close to the present trend of the po, it cannot be referred to this watercourse because its modelling is roughly contemporary with the passage of the river to the south of the collina di torino (a in fig. 2). in fact application of the local pedostratigraphic scale (arduino et al., 1984) to the soils developed on the examinated fluvial sediments has shown that the entire succession of terraces was formed between the middle pleistocene and the holocene. the upper pleistocene loess cover is in agreement with this chronological reference (forno, 1979). the different morphological features and setting of the upper terraces (a in fig. 5), particularly the differences in the number of surfaces on the two slopes and their dipping (s and ne respectively), suggest that during the lower part of the middle pleistocene the western slope hosted a s-draining and the northwestern slope a ne-draining basin (fig. 6). the same features and inclination of the lower terraces of the two slopes (b in fig. 5) and the same number of surfaces, show that during the upper part of the middle pleistocene the whole area was part of a single basin drained by a ne-flowing watercourse (fig. 6). the particular distribution of the fluvial succession of the collina di torino over a 400 metres difference in elevation is the result of the progressive deformation of the distal sectors of the alpine fans involved in the uplift (fig. 6). the considerably vertical erosion of the relief by the ancient hydrographic pattern in response to the geodynamic activity is responsible for the formation of scarps some tens of metres high between the surfaces, modelled in the tertiary substratum. the erosional surfaces at the base of the deposits, on the other hand, were worn down by lateral erosion episodes associated with local sedimentation that interrupted the dominant erosional trend. in the po plain instead are preserved the proximal sectors of the alpine fans, made of a thicker and weakly terraced or superposed alluvial succession that preserves its original geometry. lateral erosion episodes interrupted by more conspicuous depositional episodes have formed wide erosional surfaces that mark the base of the various sedimentary bodies. the deepening episodes responsible for the low scarps that separate these bodies are reduced with respect to those of the relief. this different behaviour of the plain is the result of its relative stability during the quaternary by contrast with the marked uplift of the collina di torino. the described terraced succession thus came into being in a sector of the po plain that lost its primary shape after its progressive embedding in the relief. this is in agreement with the progressive uplift of the area and the nw migration of the outer buried edge of the relief. it may be supposed that the present tributary watercourses were set up at the same time in these “new” hill sectors. their evolution has been responsible for the cutting off of the originally continuous shapes (surfaces and meanders) linked to the previous collectors and then for their preservation only on the watersheds (fig. 7). some conclusions can also be drawn concerning the rate of the deformation during the quaternary. comparison of the chronological reference of the morphological elements and the associated sediments with their altimetric distribution (difference in level of about 400 m), shows that the rate of uplift between the middle pleistocene and the holocene was of the order of 1 mm/year. fig. 7 view of the terraced surfaces of the superga ridge from valle mongreno: are recognizable three surfaces separated by hight scarps. successione terrazzata della dorsale di superga vista da valle mongreno: sono riconoscibili tre superfici terrazzate separate da alte scarpate. pleistocene deformation of the collina di torino ... 150 this rate is in agreement with the values drawn from the geodetic levellings undertaken in the period 1897-1957 (arca & beretta, 1985), which identify the present maximum uplift values of the entire piedmont area in the collina di torino (> 3 mm/yr). the presence of erosional scarps with different heights in function of their altitude suggests that the uplift was not constant, but characterized by moments of greater or lesser geodynamic activity. for a better definition of the ancient watercourses pattern that modelled the fluvial succession examined, mineralogical and petrographic investigation of the sediments associated is still in progress. acknowledgments the authors would like to thank prof. bartolini for his comments and useful suggestions on a previous draft. lavoro realizzato con il contributo finanziario dell’istituto di geoscienze e georisorse del cnr, sezione di torino. references arca s. & beretta g. (1985) prima sintesi geodeticageologica sui movimenti verticali del suolo nell’italia settentrionale (1897-1957). boll. geod. sc. aff. , 2, 125-156. arduino e., barberis e., carraro f. & forno m. g. (1984) estimating relative ages from ironoxide/total-iron ratios of soils in the western po valley, italy. geoderma, 33, 39-52, amsterdam. boano p. & forno m. g. (1997) evoluzione morfologica quaternaria del versante occidentale della collina di torino. geoitalia, 1° forum fist, bellaria 5-9 ottobre, 1997. riassunti, 2, 221-222. carraro f. (1976) diversione pleistocenica nel deflusso del bacino piemontese meridionale: un’ipotesi di lavoro. gr. st. quat. pad., 3, 89-100. carraro f., forno m. g., ricci b. & valpreda e. (1987) neotectonic map of italy (scale 1: 500.000): foglio 1 in: ambrosetti p., bosi c., carraro f., ciaranfi n., panizza m., papani g., vezzani l. & zanferrari a. (eds.) neotectonic map of italy. c.n.r., progetto finalizzato geodinamica. litografia artistica cartografica, firenze. compagnoni r. & forno m. g. (1992) significato geologico di depositi fluviali ghiaiosi pleistocenici medi nella collina di torino. il quaternario, it. journ. quat. sc., 5, 105-122. forno m. g. (1979) il “loess” della collina di torino: revisione della sua distribuzione e della sua interpretazione genetica e cronologica. geogr. fis. dinam. quatern., 2, 105-124. forno m. g. (1980) evidenza di un drenaggio abbandonato nel settore settentrionale dell'altopiano di poirino (torino). geogr. fis. dinam. quatern., 3, 61-65. forno m. g. (1982) studio geologico dell'altopiano di poirino. geogr. fis. dinam. quatern., 5, 129-162, 1 carta geol. 1: 50.000. forno m. g., ben g., boano p., bocca p., boero v. & compagnoni r. (2002) lembi di depositi fluviali provenienti dai bacini alpini nordoccidentali sulla collina di torino presso villa gualino (nw italy). il quaternario, it. journ. quat. sc., 15, 175-185. piana f. & polino r. (1994) la zona transpressiva di rio freddo e l’evoluzione convergente della collina di torino e del monferrato durante il terziario. atti tic. sc. terra, ser. spec., 1, 167-180. ms. ricevuto il 25 maggio 2004 testo definitivo ricevuto l’8 settembre 2004 ms. received: may 25, 2004 final text received: september 8, 2004 p. boano, m.g. forno & s. lucchesi imp.gregori&melelli geotourism & geomorphosites: the g.i.s. solution lucilia gregori & laura melelli dipartimento di scienze della terra, università degli studi di perugia, piazza università 06123 perugia 1lucilia@unipg.it, 2lmelelli@unipg.it abstract: l. gregori & l. melelli, geotourism & geomorphosites: the g.i.s. solution. (it issn 0394-3356, 2005). geomorphologic research which has the geographical area of umbria and the neighbouring territories as a subject of study, sheds light on some features possessing a relevant cultural and scientific value, known in literature as “geomorphosites”. nowadays geotourism is an excellent opportunity to exploit the scientific knowledge researchers have of geomorphosites as a source of didactical and economical value. the idea is to enhance the tourist attention towards geomorphosites, through the use of more traditional and better known interests. having this aim in mind, a more careful research was made for each geomorphosite. different characteristics are reported as: oenogastronomic tours, historic-artistic values, and craftsmanship activities. g.i.s. are the best instruments to manage and analyze geomorphologic data. in particular geomorphosites, which are mapped and spatially georeferenced have a geographical characterization so that they can be best studied through the use of g.i.s. in g.i.s. different functions are available as querying maps, or building relations in relational database (one to one or many to one) in order to obtain detailed tourist itineraries. riassunto: l. gregori & l. melelli, geoturismo e geomorfositi: una soluzione in ambiente gis. (it issn 0394-3356, 2005). da alcuni anni, lo studio delle caratteristiche geomorfologiche del territorio, ha messo in evidenza in umbria e nelle aree limitrofe, (analogamente al lavoro svolto in italia e all’estero) la presenza di forme con alto valore scientifico e culturale, definite “geomorfositi”. un nuovo approccio alla conoscenza e alla promozione di questi siti è costituito dal loro inserimento in nuove nicchie turistiche. nasce così il “geoturismo” ovvero un turismo che privilegia, lungo i consueti circuiti, mete con alto valore scientifico, geologico e geomorfologico, consentendone il passaggio da un ambito strettamente accademico ad uno gestionale economico. nonostante il più alto livello culturale del turista medio, i geomorfositi rimangono ancora un campo poco o nulla esplorato dagli attuali flussi turistici. trovare nuovi modi per far avvicinare il turista ai geomorfositi, passando attraverso interessi più tradizionali e già testati, è lo scopo principale del presente lavoro. i sistemi informativi geografici (g.i.s.), intesi come nuovi strumenti per la gestione e l’analisi di dati geografici, rappresentano un utile mezzo per il management dei beni geomorfologici e per la loro diffusione in ambito turistico. gli aspetti più “tradizionali”, che costituiscono un valore aggiunto al bene geologico-ambientale, oltre a quelli di carattere strettamente scientifico, sono implementati nel database relazionale del progetto: gli elementi geologico-geomorfologici, le valenze storico/artistiche, culturali s.l., l’artigianato e le tradizioni popolari, il valore paesaggistico/ambientale, la progettazione di percorsi escursionistici ecc. il carattere territoriale dei geomorfositi (forme presenti nello spazio geografico, georeferenziabili e cartografabili), collegato ad un certo numero di attributi, li rende gli oggetti ideali per essere gestiti dai sistemi g.i.s. utilizzando le potenzialità di tali sistemi (connessioni tra tabelle con relazioni uno a uno e molti a uno e/o formulazione di query) è possibile interrogare il database per ottenere la selezione dei geomorfositi che rispondono alle specifiche esigenze turistiche. la proprietà geografica del dato (georeferenziazione) permette inoltre, una volta avvenuta la selezione, di creare percorsi di collegamento tra i siti, che ne tengano in considerazione ulteriori caratteristiche come la fruibilità o l’accessibilità keywords: geographical information system (g.i.s.), geomorphosite, geoturism. parole chiave: sistemi informativi geografici (g.i.s.), geomorfositi, geoturismo. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 285-292 1. introduction new research perspectives in geological and geomorphologic disciplines have led to define and evaluate forms, known in literature as geomorphosites. they possess a relevant scientific, cultural and socio-economic value, (brancucci & burlando, 2000; panizza & piacente, 2002a; panizza & piacente, 2002b; panizza, 1992; poli, 1999). nowadays the research of specific methods to define these sites is one of the main aims in national and international literature (d’andrea & di legino, 2003; wimbledon, 1996). in addition the application of geographic information system (g.i.s.) has a not well-defined role yet. in many cases the g.i.s. systems can elaborate an interactive and real-timeupdatable cartography (carton et al., 2003). also some attempts have been carried on to use g.i.s. as an analytical way to fix up a methodology for weighing different attributes of the geomorphosites. at this purpose we can obtain a model to distinguish many forms on the territory (giusti & gonzalez-diez, 2000). still we can find some difficulties in transferring themes of geomorphosites from a strictly academic sphere to a one more accessible and useful for the community. particularly, these themes can integrate with anthropic tissue, which they belong to. therefore, to include geomorphosites in articulate and studied tourist-didactic routes seems to be a scientific and tourist relevant purpose (massoli-novelli, 2003). the use of g.i.s., more than every other traditional cartographical instrument, enables to manage different attributes of geomorphosites and gives back a real-time updatable, interactive and extremely flexible data. one of the main difficulties, linked to the diffusion 286 l. gregori & l. melelli of geomorphosites in tourist circuits, is their sectorial nature. until know, the interest in this subject was restricted only to geologists, naturalists, geographers, and not extended to common people. the implementation of databases inside gis projects takes into account the necessity of turning a bigger number of visitors towards geotourist routes. therefore, what can be done is to determine and study geomorphosites along well known tourist routes. the central core of db consists of a census and subsequent evaluation of existing additional values near a geomorphosite, like museums, naturalistic paths, historic centres with festivals and popular traditions. in the paragraph dedicated to db structure, these additional values will be described in detail. 2. geomorphosites in umbria several sites of relevant geological-geomorphologic aspects can be marked in umbria (fig. 1): in certain cases these had an influence onto the historic and cultural local evolution of the territory (like for assisi, trasimeno lake, “mesa” of orvieto, mounts sibillini area, marmore falls and others). nowadays they conjugate environmental realities and territorial intrinsic bents, potential and expressed for a synthetic vision of all possible scientific and cultural aspects, constituting an important resource and/or wealth of our territory. determination and census of geomorphosites in umbria and in neighbouring areas have led to the identification of nineteen sites, some of which have been exclusively selected for their geomorphologic characteristics. others have been chosen for the peculiarity of the related cultural and historical characteristics. the “intermountain basins” phenomenon are an interesting example of geomorphosites in central apennines and particularly in the umbrian one. they are wide depressed areas linked to extending plio-pleistocenic tectonics, characterizing western slopes of apennine structures. in “gubbio basin”, the depressed area of “gualdo tadino”, “colfiorito plains” and “pian grande” there are morphologic evidences of tectonic activity (triangular facets) and of karst morphogenesis (polije). these areas gain an important morphological role, because they are identified as tectonics depressions linked to apennines evolution. moreover they constitute a particularly charming landscape which can be considered different seasons as a tourist point of interest, also within a gastronomic, sports-tourist approach. umbrian apennine, in virtue of a massive calcareous formation, presents picturesque landscapes and characteristic phenomena of karst morphogenesis, both hypogean and epigean, and in macro and microforms. karst polijes show several animal species and endemic vegetable associations. even brachy-anticline of mount subasio with “mortari” (depressions with doline shape set along the top of the mountain) are particularly interesting for form and dimension and have an evident scenic value. climatic conditions inside mortari also allow the existence of phytosociologic associations. among hypogean karst morphotypes the complex of mount cucco caves represents the broadest system of central italy, while the hypogean cavities of mount maggiore abbey, developed on the inside limestone “horizons”, intercalated with a flysch sequence, fig. 1 location map. localizzazione dell’area di studio. involve less known but very interesting sites, from a genetic and evolutive point of view and scientifically attention worthy as well. in umbria morphogenetic fluvial agent is responsible for peculiar forms as rio freddo gorge and for the carving of gorghe (fig. 2), where lithoselection phenomena permit overhang of fault gravel creating something like a “range reversal”. these sites can be joined up in a speleological route as well as they allow an epigean hiking both along rio freddo “potholes” and gorghe “wall”, where the study of geomorphologic phenomena and sport activities combine extremely well. in both cases, scientific value, extraordinary scenic impact and interesting morphogenetic processes on one hand and tourist and technical-sport use on the other, propose a very good scientific and tourist offer. in southern umbria there is a magnificent lithogenetic process: marmore falls. the majestic waterfall, made by river velino waters flowing into river nera, rises artificially, thanks to a waters diversion projected and realized since roman age. falling processes of waters, saturated of calcium carbonate, have raised year by year a difference in level. this has happened probably already for structural reasons, increasing therefore leaving of massive travertine deposits and forming a series of karst and “pseudo karst” shapes, both of them present in travertine basin of the cliff and in the entire territory of marmore piano. fruition of beauties of falls, lithogenetic processes linked to travertine deposition, “speleological” routes inside cliff caves, rafting and torrentism activities along nera river give to this site considerable potentialities. the springs of clitunno river, at the base of the village of campello range structure, represent a peculiar site linked to interaction of fluvial processes, karts and/or tectonic, through a complex genesis and evolution of karst “essurgenze”. therefore, they represent a unique landscape, extolled also by artists and poets of any age, from plinio to carducci. other geomorphosites are included in this survey because their genesis is bound to important towns, characterized by a rich cultural and historic wealth. the uniqueness of the location of some towns is due to well identifiable structural elements and morphogenetic processes whose study permits to understand for example why a city had a particular monumental and town-planning-development. perugia historical centre, e.g., is situated on the top of the hill identified as river tevere paleodelta, that flowed into tiberino lake in plio-pleistocenic age. structural landforms (mesas) of orvieto and civita di bagnoregio (fig. 3) are the results of morphoselection phenomena which isolated ranges (volcanic tuffs) and carved the spectacular badlands near civita. the “dying village” of civita represents a symbolic case of contradictory interventions to safeguard naturalistic aspects of a geomorphosite (badlands-landscape) and of its contemporary drainage work, held out of a historic centre consolidation. orvieto represents a spectacular example of structural cliff “lived” all along its surface and its thickness (several hollows inside the cliff were used in past times as reservoirs and cellars). in the area included between alfina plateau and the cliff, moreover, an inte287geotourism and geomorphosites ... resting archaeological site has been discovered, which testifies an intense human presence starting from etruscan epoch and adds value to this site. cerbaiolo hermitage, located on the top of a cliff involved in an important lateral spread phenomenon, or vernazzano tower, near trasimeno lake, leaning further to a subsidence movement, represent attractive sites for their characterizing evolutive aspects and well suitable to be put in well known tourist routes. trasimeno lake has been included in geomorphosites list for its peculiar character of tectonic lake (the most ancient in italy) and also for its faunistic and floristic characteristics all along its shores. near ficulle/allerona are visible particularly spectacular badlands-morphotypes, not very well-known yet, but worthy of being included in a geotouristic route, also taking into account its special character of terroir, giving important “wine-making” value to this zone; in these territories, in fact, the famous “muffati” wines are made and their production is linked to the local pedoclimate. at last, in the most southern area of umbria there fig. 2 gorghe wall. la muraglia naturale delle gorghe. fig. 3 civita di bagnoregio: the “dyng village”. civita di bagnoregio: la “città che muore”. 288 is the site of dunarobba fossil forest, which is a geological and palaeontologist worldwide known site, with a high geotourist value. the presence of several taxodiacee tree trunks, still in their physiologic position, allows to individuate the existence of a fluvial-lacustrine pliocenic territory and a landscaping wreckage from the past. 3. the structure of a g.i.s. (geographic information system) g.i.s. is a computer-based system for acquisition, storage, retrieval, analysis and display of spatial (locationally-defined) data. we could define geomorphosites as geographical data and we could import and analyze them like spatial objects. every object constitutes a georeferenceable form, according to a coordinate system. in addition, their complete and detailed knowledge necessarily implies the collection of individual and characterizing attributes. the structure of any g.i.s. instruments is representable by the formula: n [g – a] where n represents the number of informative layers to be implemented in a project (layers); g is the space-geographical component used to georeference. it is referred to geometric and topologic components of the objects. it describes the shape (geometry), the location (latitude and longitude) and the spatial relantionships (topology). topological properties of the figures do not change under bicontinuous one-to-one transformations (called homeomorphisms). two figures that can be deformed one into the other are called homeomorphic, and are considered to be the same from the topological point of view. the quantity a corresponds to the attributes characterizing the object. it is referred to statistical and qualitative data aspects. it describes the meaning and the magnitude of the data. theoretically, the variable a includes an unlimited whole of information, differing in contents and sizes (number, string, boolean, date). the different structure indeed leaves out any correlation, and, in most cases, does not allow various layers to communicate between each other in order to effectuate spatial analysis operations. on the other hand it gives the possibility the use of traditional calculations to compare alphanumeric values. the quantity g, on the contrary, aside from the kind of object which it refers to, maintains the same construction (latitude and longitude) and it gives the possibility to exchange information between layers and the application of new spatial operators, as connection, adjacency or closeness. it is this part of a gis structure that allows spatial analysis calculations. the approach to the use of a g.i.s. system can be of three types: cartographic, database oriented and analytical. in the first one, g.i.s. is only an interactive container of maps which can give back and in real time updatable cartographies. a map-oriented gis is a display system where each input data set is a raster document and the output is always a new map. the second approach is a management system based on the amount of imported attributes (dbms, data base management system) which is considered to be the essential part of the project, and onto the operator’s types applicable to analysis between different statements. the third one is based on analysis and model operations between implemented data. from this point of view, g.i.s. is a science concerning spatial information and analysis and not only a simple technology. this approach allows to realize the best from gis potentialities. in this research we present geomorphosites management with a database and analytical oriented g.i.s. system, in order to take advantage of the potentialities of sites for tourist purposes. the quantity g is compiled with coordinates referred to each geomorphosite, located as vector-punctual datum. the term a is articulated into a sequence of tables, whose structure is the project main element (data base oriented). these tables are linked one to another by a primary key (id field). the analysis is the final step of the project to find the closest facility (referring to anything providing a service like a geomorphosite, closest to a given location like hotels, roads, museums or other service areas) or to find the best route (the best way to get from one location to another or the best way to visit several locations). 4. the project implementation every g.i.s. project is made up of three phases: data collection, analysis and management of obtained elaborations. 4.1 inventory application collection of the data is the first step to build up a project and therefore its correct evaluation is fundamental in order to obtain, at the end of the analysis processes, the desired results. the quality of a project is not directly proportional to the quantity of imported data or to the number of effectuated analysis operations. on the contrary, the choice of initial data has to be limited to the less possible number of cartographic bases and databases required for further elaborations, also taking into account the high expenses for data acquisition. after this stage, a pre-elaboration is carried on, including eventual formats conversion, cartographic bases georeference and possible connections to pre-existing databases. a digital elevation model with pixel resolution 90x90m (taramelli & stark; http://geomorph.ldeo. columbia.edu/italy_srtm/2003) has been acquired in the project, covering the entire umbrian regional territory, a topographic base, with scale 1:25.000 igm and a roadgraphs with the main regional highways. the core of the project is constituted by a total amount of eight tables, on which the following analysis operations have been carried on. every table is made up of nineteen records (each record corresponds to a registered geomorphosite) and of a varying number of columns. every record contains an id (primary key) column, reproducing a progressive number, which is unique for each site. thanks to this l. gregori & l. melelli 289 column, one can elaborate joint operations between statement data in subsequent operations. each column field has two possible formats: a string, when it contains descriptive information related to the same column (e.g. formation type in geology) and numerical, if the information has to be quantified in order to be compared with other fields. in this case the numeric value 1 corresponds to a minimum weight of the expressed datum; 2 has a medium value and 3 a maximum one with a single score criterion based on bibliography and acquired knowledge. for those data to be inserted we have referred to the italian national geologic service forms for the census of geomorphosites on national territory, introducing suitable changes considering this project aims. tables can be grouped in three main knots: 1) scientific and identificative 2) kind of tourist interest 3) use and vulnerability in the first group information related to localization of geomorphosites are collected, together with their soundness and scientific typology characteristics. it includes the following tables: a. location; with columns named: • toponym (string); • town council (string); • province (string); • region (string); • latitude (string); • longitude (string); • above sea-level quote expressed in meters (numerical); • area occupied by geomorphosites expressed in square meters (numerical); • igm table scale 1:25.000 (string); • link to eventual further additional cartographic bases (string); b. interest level, the interest level degree of each geomorphosite with columns named: • world-wide (numerical); • european (numerical); • national (numerical); • local (numerical); c. geology, with columns named: • prevailing geological formation (string); • prevailing lithotype (string); • prevailing formation chronostratigraphic age (string); • shape formation age (string); d. processes generating shape, with columns named: • tectonic (numerical); • gravitative (numerical); • fluvial (numerical); • volcanic (numerical); • karst (numerical); • glacial (numerical); • periglacial (numerical); • aeolian (numerical); • marine (numerical); • anthropic (numerical). fields have a numerical value from 1 to 3 according to the importance every process had when the form has been generated. e. processes modelling shape. fields pattern is like the one reproduced for processes generating shape. the second group is marked with a single table, but it seems to be the most important to finalize geomorphosites from a tourist point of view, because it contains information related to better known and usual tourist interests. numerical values, identifying for each field a minimum and a maximum value, are the results of a careful bibliographic research. the choice of column types has been conditioned by tourist features in umbria, but it is also possible to modify this number with different typologies for different territorial realities. a. other interest, with columns named: • didactic (numerical); • cultural and artistic (numerical); • historical (numerical); • museums related (numerical); • hiking (numerical); • sport (numerical); • oeno-gastronomic (numerical); • local craftsmanship (numerical); • festival and local traditions (numerical). the last group lists informations about the accessibility of each geomorphosite and about hosting facilities for tourists with different needs. moreover, one can quantify hazard conditions to which a geomorphosite can be exposed, taking into account a future preservation of the site. groups of data are made up of two statements: a. use, with columns named: • equipped area (numerical); • practicability (numerical); • vulnerability level (numerical). b. exploitation-preservation, with columns named: • preservation state (numerical); • risk of natural deterioration (numerical); • risk of anthropic deterioration (numerical); • protection need (numerical). 4.2 analysis application for this project we have used the software esri arc view 3.3. using the column of identification codes, which are the same for each statement, it is possible to realize joint operations and queries between tables (fig. 4 and fig. 5). tables structure has the purpose of creating new and temporary tables satisfying each tourist needs. relational db structure is absolutely the most suitable in this way, allowing the connection of different fields through the common id, on which one can effectuate specific queries. it is possible to question something like “select all geomorphosites having an at least national level of interest, providing with equipped areas of a medium level and having in the closeness interesting oeno-gastronomic routes”. this command is translated into simple algorithms, easy to build through specific tools of relative gis software. therefore it is possible to satisfy different tourist profiles. the temporary tables calculated from various queries reflects specific requirements. the tourist operators have the possibility to geotourism and geomorphosites ... 290 l. gregori & l. melelli fig. 4 example of table, reproducing different types of interests related to geomorphosites, with numerical score for each cell. esempio di selezione su tabella riportante i diversi interessi correlati ai geomorfositi con valori numerici in ogni cella. fig. 5 example of query to locate geomorphosites with value, related to the presence of excursion and partly eno-gastronomical routes. yellow pointed out records represent geomorphosites satisfying this query. esempio di interrogazione volta all’individuazione dei geomorfositi con medio -alto valore eno-gastronomico e alto valore escursionistico. i records contrassegnati in giallo rappresentano i geomorfositi in grado di soddisfare l’interrogazione. select only the fields linked to tourist request interests (fig. 5). it is possible, in this way, to create temporary tables referred only to some specific geomorphosites. these geomorphosites have their specific attributes regarding scientific value and location, but above all, they have specific characteristics that satisfy the tourist interests, like cltural-artistic or oeno-gastronomic targets. it is possible to induce a larger number of tourists to visit geomorphosites if they know that they can find in the same places, traditional tourists attractions. but operations of “selection”, “connection” and “query” on statements can be developed by any program of db management. the added value of a gis system is, in this specific case, the capacity of positioning the obtained results on georeferenced maps (selected geomorphosites). moreover, the importation of the project road-graphs, permits to build real routes to be inserted into tourism proposals, without forcing the visitor to follow pre-packaged and in some cases far away from his own interests trips. network analysis tools in different gis allow to find the best route and the closest facility to a service areas. by finding the best route it is possible to plan the visits to several locations and the related closest services. in figure 6 it is possible to observe the best routes between several geomorphosites (in blue) or the shortest road (in red). 4.3 management system in this phase generally thematic charts, cartograms, diagrams, graphics and statistics, and descriptive reports are produced to support decisional projects of future administrations. in the case of geomorphosites, final output aims to determine, on cartographic base (and therefore immediately receivable from tourists) sets of selected sites. cartographic base can show several itineraries linking different sites and containing a set of additional information. the legend enclosed in each map can be “widen” in several ways, showing information otherwise implicit on a simple paper support. 5. conclusion geotourism is taking its first steps both in italy and abroad. recently cultural standard of medium tourists is increasing and therefore new realities like geosites/geomorphosites can be the object of a new interest. routes conjugating morphologic characters and tourist interests give the opportunity to convey a wider tourist user to geomorphosites zones. particularly the new approach to geotourism starting from g.i.s. is founded on geographic nature of geomorphosites and contemporary on the supporting structure of g.i.s. systems, that permits to implement a project, oriented to the management of attributes of these sites. typical operations of geographic informative systems allow, in this way, to obtain personalized destinations and routes collecting tourists’ interests, and at the same time, more scientific information about the sites. considering the fact that g.i.s. systems are growing fast both in private and in administrative sector, that they can manage a theoretically endless number of information and can correlate new and traditional cartography, it is evident the utility of biasing the research towards this field. therefore, an increasing development of geotourism sector could boost the diffusion of knowledge within the limits of earth science and a planning in the distribution of tourist interest sites inside known routes and farther from traditional but still interesting tracks. references brancucci g. & burlando m. (2000) la salvaguardia del patrimonio geologico. scelta strategica per il territorio. l’esperienza della liguria franco angeli ed., 96 pp. c arton a., c oratza p & m archetti m. (2003) methodological proposal for mapping geomorphosites proc. workshop “geomorphological sites: assessment and mapping”, cagliari (italy), 1-5 october 2003, pp. 21-22. d’a ndrea m. & d i l egino f. (2003) progetto “conservazione del patrimonio geologico italiano”. i censimenti sui siti di interesse geologico in italia, aggiornato a dicembre 2002 geologia dell’ambiente, sigea, 1, pp. 154-161. giusti c. & gonzalez-diez a. (2000) a methodological approach for the evaluation of impact on sites of geomorphological interest (sgi), using gis techniques int. archives of photogrammetry and remote sensing, vol. xxxiii, (b7), pp. 47-53. massoli-novelli r. (2003) geositi, geoturismo e sviluppo sostenibile geologia dell’ambiente, sigea, 1, pp. 167-170. 291geotourism and geomorphosites ... fig. 6 example of a map with geomorphosites (blue targets). the geomorphosites marked with red targets are selected by a specific query (high value of hiking routes). the red line shows the best route (best accessibility) to visit all the selected geomorphosites. the blue line shows the shortest route that link the selected geomorphosites. esempio di cartografia riportante una serie di geomorfositi (contrassegnati da simboli in blu). i siti evidenziati in rosso sono quelli selezionati sulla base di un’interrogazione spaziale (quali sono i siti con maggior valore dell’aspetto escursionistico). la linea rossa mostra il percorso che collega i suddetti geomorfositi con strade facilmente percorribili. la linea blu, al contrario, mostra il percorso più breve tra i geomorfositi selezionati. panizza m. (1992) sulla valutazione dei beni ambientali mem. descr. carta geol. d’it., xlii, pp. 479-484. panizza m. & piacente s. (2002a) geositi nel paesaggio italiano. ricerca, valutazione e valorizzazione. un progetto di ricerca per una nuova cultura geologica geologia dell’ambiente, sigea, 2, pp. 3-4. panizza m. & piacente s. (2002b) the geomorphosites between scientific research, cultural integration and artistic suggestion workshop geomorphological sites: research, assessment and improvement, modena (italy) 19 -22 june. poli g. (1999) geositi testimoni del tempo. fondamenti per la conservazione del patrimonio geologico regione emilia-romagna, ed. pendragon, 258 pp wimbledon w.a.p. (1996) geological world heritage: a global comparative site inventory to enable prioritisation for conservation proceedings ii° int. sympos. progeo on conservation of our geological heritage, serv. geol. naz., 20-22 may, rome, pp. 45-60. 292 l. gregori & l. melelli imp.colorti_barca_melis 87 1. introduction the new sheet “557” cagliari (carg project) produced a map of the quaternary syntems, however the results of the new radiometric datings were not exhaustive and sometimes contradictory. the groups working on continental and marine areas reached different conclusions on the chronology of the deposits: some coastal deposits have been included in the subsynthem of cala mosca (tyrrhenian) although we should refer them to the holocene. however, the distribution of the tyrrhenian deposits was reduced and the is arenas beach ridge grouped within the holocene. we report the elements supporting a holocene age for the coastal deposits. 2. geological setting the campidano is a plio-pleistocene nnw-sse oriented subsiding basin. early pliocene marine sediments crop out on the western side at capo frasca and capo s.marco up to 50 m asl. early pliocene sediments with globorotalia margaritae, puncticulata and crassaformis have been found at depth in the cagliari gulf (murru, 1983) and in the oristano 1 and 2 boreholes (727 and -666 m respectively; (pomesano-cherchi, 1971) (fig.1a). in the oristano 1, these sediments are covered with basalts, similar to those dated at 3 ma in the sinis peninsula. they are in turn overlaid by continental deposits suggesting a great mobility of the campidano. along the cagliari coast, nne-sse normal faults, that in the nearby villacidro sheet cut late pleistocene alluvial fan deposits, drove the river network. 3. litho-, morpho-, bioand pedo-stratigraphic characteristics the quaternary deposits have been subdivided into the late pleistocene porto vesme sinthem (pvm), comprising the cala mosca (pvm1; “tyrrhenian” auct.) and the portoscuso subsynthem (pvm2a), and the holocene sinthem. the pvm2a consists of gravelly alluvial fans, up to ca 10 m in thickness, that are truncated by marine cliffs and river incision. the top of the late pleistocene rio corongiu terraced alluvial fan, to the east of the poetto beach, is preserved for ca 10 km from the apical zone (205 m), to the rear of the coastline (m. 28). soil with well developed argillic horizons and with profiles a-bt-c, a-btc-c and a-btg-cg (typic, ultic e aquic paleoxeralf, apat, 2005) are locally preserved. the argillic horizons in places overlie carbonate-rich horizons but the latter develop also on top of the argillic horizons (a-bt-ck e a-btk-ckm, calcic and petrocalcic paleoxeralf). these are early holocene soils because their degree of weathering is not comparable with the last interglacial soils of the apennines (coltorti & pieruccini, 2005). the pvm1, crop out only at cala mosca (capo s.elia), that is the type locality of the “tyrrhenian”, the penultimate high standing marine stage (issel, 1914; spano, 1980; ulzega et alii, 1982) and at marina piccola (fig.1a). a few decimetres of gravels and bioclastic sands, including strombus bubonius, lay unconformably on a rocky marine platform whose elevation varies from ca + 1 m to + 4 m asl. they are sealed with over 7 m of debris and aeolian sands. at cala mosca, these sediments are also found inside a coastal cave with mussel boreholes up to 3.8 m asl. the holocene deposits that after the recommendations of geologists dealing with the marine areas, have been mapped as “tyrrhenian” in age, crop out at sa illetta and at foxi (fig. 2). at sa illetta sands and calcarenites constitute the remains of an inner beach ridge up to ca. 1,5 m asl while at foxi they crop out along the beach. molluscs are typical of coastal and lagoon environments. small colonies of cladocora coespitosa in living position are present in both sites. incised into the pleistocene terraced deposits, there is a holocene alluvial gravelly terrace locally containing polmonates and thin buried soil (a1c or a1ck profile). it is cut by a coastal cliff sealed with alluvial or beach deposits. nowadays, most rivers are bordered by artificial levees but in the past they had a braided pattern associated with a high solid load due to accelerated slope erosion. laterally, they interlayer with alluvial fan deposits. prior to this braided pattern, air-photos reveal that meanders occupied the plain. close to the coastline the riu corongiu create a small fan delta whilst the flumini mannu generated cuspidate deltas inside the s.gilla lagoon. in the quartu bay the rivers enter the molentargius swamp, originated by the is arenas beach ridge made with even laminated sands and gravels up to ca. 5 m asl,. organic lagoon mud has recently been dredged at a depth of 8 m. we recognised only present-day mollusc fauna but ulzega et alii (1982) mention the presence of strombus bubonius, although it is possible that it was reworked from older layers. stable or mobile sea-level, stable or mobile sardinia during the holocene: evidence from the cagliari gulf mauro coltorti 1, s. barca 2, e. melis 3 1 dipartimento di scienze della terra, via di laterina, 8 53100 siena –coltorti@unisi.it 2 dipartimento di scienze della terra, via trentino, 51 09100 cagliari 3 progemisa s.p.a via contivecchi, 7 cagliari 88 f ig .1 a s ke tc h m ap o f th e s in th e m s o f th e c ag lia ri s h e e t; 1 . l at e p le is to c e n e t e rr ac e d a llu vi al f an ; 2 . h o lo c e n e t e rr ac e d a llu vi al p la in ; 3 . h o lo c e n e a llu vi al d e p o si ts ; 4 . h o lo c e n e b e ac h d e p o si ts ; 5 . lo c at io n o f th e s e is m ic p ro fil e o f fig .2 ; 6 . m ai n s it e s in t h e t e xt : 1 . s .l o re n zo ; 2 . f o xi ; 3 . is a re n as ; 4 .p ra n ’e s ill i; 5 . s a m an n a m at ta ( n o t in t h e m ap b u t re p o rt e d i n t h e c lo se r ar e a o ve r th e s am e u n it ); 6 . s .m ic h e le c e m e te ry ; 7 . s a ill e tt a; 8 . c al a m o sc a; 9 . m ar in a p ic c o la ; 1 0 . s ta g n o d i s im b ir iz zi ; 1 1 . s e d d a is a m m o st u s; 1 2 , p ra n i ‘e s ill i; 1 3 . p o e tt o ; 1 4 ; a rc u m ai n i; 1 5 , l a p la ya ; 1 6 . s an ta r e p ar at a: 1 7 . c al a s p in o sa ; 1 8 . c ap o s .m ar c o ; 1 9 ; c ap o f ra sc a; 2 0 s .a n ti o c o ; 2 1 . p o rt o v e sm e ; 2 2 . m at za c c ar a; 2 3 . c ix e rr i b as in ; 2 4 . s am as si ; b , s tr at ig ra p h ic r e la ti o n sh ip b e tw e e n t h e d iff e re n t si n th e m s. 89 4. chronostratigraphic data a new u/th dating on cladocora found in cala mosca gave 122,11+5,3/-5,01 ka (em-216-6375) but the low isotopic 230th/232thratio suggests contamination. a date of 138 ± 8 ka was obtained by hearthy et alii (1986) but the sample had a percentage of calcite exceeding 9%. when calcite exceeds 5%, the 230th/234uratio or the 230th/238uratio ratio are not measured, samples have to be rejected (kauffmann, 1986). belluomini et alii (1986) utilising the isoleucine epimerization, report an age of over 250 ka. hearty et alii (1986) utilises the ratio between arca/glicimeris, because the results from a single species are unreliable. the last interglacial shells would have a ratio close to 1,31 but at cala mosca it varies between 1,37 (lower part) and 0,86 (top). however, this method is unreliable because the decaying ratio varies with the temperature (mccarroll, 2002; walker, 2005). the chronology of the pvm2a fluvial deposits is based on a date of 34.810 + 2880/-2120 bp (amskia24070) of organic material found 10 m below terraced alluvial fan gravels at samassi. the holocene terraced deposits have been dated at sa matta manna. polmonate shells found in silty layers in the lower part of the sequence gave 8.680 ± 60 bp (ams, beta150624). in the s.lorenzo area and at s.michele cemetery (fig.1a) rolled fragments of pottery testify that the incision occurred after the early neolithic. at foxi the whole rock dating of calcarenites gave 23.140 ± 90 bp (beta-138678) while a u/th of corals gave 53,3 +0,8/-0,7 ka (em-130-6376). at sa illetta, a sample of fig. 2 the seismic profile (a) located to the south of la playa beach ridge (fig.1) used by orrù et al. (2004) to establish an unconformity between holocene and tyrrhenian deposits (b). interlayering is evident in our interpretation (c). 90 shell was dated at 40.420 ± 1.120 bp (ams, beta138680) while the whole rock was 18.880 ± 50 bp (ams, beta-138675). ulzega & hearthy (1986) also obtained an unreliable u/th dating of cladocora of 149 ± 10 ka because stratigraphy, calcite content and isotopic ratios are unknown. at is arenas a sample of shells was dated at 26.740 ± 360 bp (ams, beta-138676). isoleucine epimerization allowed belluomini et alii (1986) and hearthy et alii (1986) to attribute the deposits to the neo-tyrrhenian. ulzega & hearthy (1986) report corals, never published in a comprehensive way, coming from the poetto and la playa beaches, dated respectively at 6,5 and 7 ka. holocene datings also come from marine shells found in the clay filling in front of the cagliari port (orrù et alii, 2004). 5. discussion and conclusions cala mosca and marina piccola constitute the older units cropping out below debris and aeolian deposits (fig.1b). terraced late pleistocene alluvial fans are the older deposits inland. their incision was filled with alluvial deposits later incised and filled with the actual fluvial sediments. the latter unit shows a transition to coastal deposits subdivided into a number of beach ridges and lagoon deposits similar to the adriatic (coltorti, 1997) and tyrrhenian coasts (boschian et al., 2006). the reliability of radiometric dates of organic matter and polmonates in late pleistocene and holocene alluvial deposits is confirmed by the rolled pottery. the dating of the shell remains at sa illetta, is arenas and foxi is evidently unreliable. these are holocene beach ridges lying at the base of marine and fluvial escarpments that affect the late pleistocene terraced deposits (fig.1b). aeolian deposits or paleosoils are absent. shells found in lagoon deposits at + 6 m asl at the vascone site (matzaccara, carbonia sheet) dated to 36.220 ± 730 b.p. (beta-138698) but at the same layer with a few pieces of rolled pottery confirm a systematic error for these holocene deposits. the older ages of the shells could be due to the hard water effect or diagenetic processes. also the marine deposits of santa reparata (fig.1a), attributed to last interglacial with isoleucine epimerization (ulzega & hearthy, 1986), are holocene in age. in fact, they overlie (and not underlie) aeolian deposits that in the nearby cala spinosa contain polmonate shells dated to 20.010 ± 60 bp (ams; beta 138687). the sa illetta and is arenas beach ridges were attributed to the “tyrrhenian” also because, following an eustatic model, a series of deep narrow valleys would have cut the “tyrrhenian” deposits during the last glaciation. however, a deposition dominated by climatic processes follows an eventual erosion as a consequence of sea level fall (plint et al., 1992) and seismic profiles demonstrated a strong sedimentation before 18 ka down to the shelf break (lecca et alii, 1998). in particular is arenas beach ridge completely dams the valley and if it is tyrrhenian in age, no later erosion and limited sedimentation occurred in the basin. the erosional valleys that in the model of pecorini (1986) and orrù et alii (2004) were carved during the cold period in our idea were modelled during the late glacial/early holocene, after the reduction of the solid load resulting from reforestation while the sea level was still low. this is confirmed by the holocene age of the valley filling and by the interlayering visible in our reinterpretation of the orrù’s seismic profile (fig. 2). barrier beaches are the result of long-shore drifting of river sediments after neolithic soil erosion. the high elevations of the sa illetta and is arenas coastal deposits was also used to support a “tyrrhenian age because holocene storm deposits are not expected above 4 m asl (issel, 1914; ulzega et alii, 1982). however, elevation must not aprioristically represent a proof. if elevation and not stratigraphy should be the criteria, new discoveries are impossible. stratigraphy suggests that the holocene sea-level rose higher than the present day and/or that some parts of sardinia are affected by positive tectonic movements. sardegna is considered a stable region but the geological setting and the faults cutting the late pleistocene deposits suggest otherwise. the “tyrrhenian” tidal notches in the orosei gulf (carobene & pasini (1973) also demonstrated differential uplift. moreover, if the dating of cladocora found at the sea level and dated ca 7 ka at la playa and poetto (ulzega & hearthy (1986) are reliable they confirm a higher sea level during the early holocene or tectonic movements. in fact, today cladocora grow between 4 and 10 m bsl. if the holocene sea level never exceeded the present day one (lambeck et alii, 2004) the cagliari area is affected by uplift. however, it is our opinion that the curve of the holocene sea level rise is still far from resolved. acknowledgements the work is the result of the carg project sheet 557, cagliari, legge 305/89, convenzione apat serv.geol.d’it. regione autonoma sardegna. we thank the progemisa for the continued logistic and technical support. references apat, (2005) note illustrative alla carta geologica alla scala 1:50.000 f.557 cagliari. selca ed., 240 pp. belluomini g., branca m., delitala l., pecorini g. & spano c., (1986) isoleucine epimerization dating of quaternary marine deposits in sardinia, italy. z.geomorph., suppl.bd.62, 109-117. boschian g., bossio a., dall’antonia b. & mazzanti e., (2006) il quaternario della toscana costiera. studi costieri, 12, 3-207. carobene l. & pasini g., (1973) contributo alla conoscenza del pleistocene superiore e dell’olocene del golfo di orosei (sardegna orientale) . boll.soc.adriatica di scienze, trieste, 64, 5-36. coltorti m., (1997) human impact in the holocene fluvial and coastal evolution of the marche region. central italy. catena, 30, 311-335. c oltorti m. & p ieruccini p., (2006) the last interglacial pedocomplexes in the lithoand morpho-stratigraphical framework of the centralnorthern apennines. quaternary international, 156-157, 118-132. hearthy p.j., (1986) an inventory of last interglacial age deposits from the mediterranean basin: a 91 study of isoleucine epimerisation and uranium series dating. z. geomorphologie, n.f., 62, 51-70. hearthy p.j., miller g.h., stearns c.e., & szabo b.j., (1986) aminostratigraphy of quaternary shorelines in the mediterranean basin. geol. soc. am. bull., 97, 850-858. issel a. (1914) lembi fossiliferi quaternari e recenti osservati nella sardegna meridionale dal prof. d. lovisato. rend. acc. naz. lincei, cl. sc. fis. mat. nat., 23, 759-770. lambeck k., antonioli f., purcell a. & silenzi s., (2004) sea level changes along the italian coast for the past 10,000 yr. quaternary science review, 23, 1567-1598. lecca l., panizza v. & pisano s., (1998) the sedimentary framework of cagliari basin: a pliopleistocene underfed rift basin in the southern sardinia margin. il quaternario, 11(2), 301-318. kauffman a., (1986) the distribution of 238th/234u ages in corals and the number of last interglacial high stands. quatern.res., 25, 55-62. muru m. (1983) presenza di pliocene inferiore nel sottosuolo di quartu sant'elena (cagliari). boll. soc. sarda sc. nat., 22, 93-98. mccarroll d, (2002) amino-acid geochronology and the british pleistocene: secure stratigraphical framework or a case of circular reasoning? journ. quat.sci., 17, 647-651. orrù p., antonioli f., lambeck k., verrubi v., lecca c., pintus c. & porcu a. (2004) holocene sea level change of the cagliari. quaternaria nova 8, 193212. pecorini g., (1986) considerazioni geomorfologiche intorno a s.igia, (stagno di s.gilla, cagliari). in s.igia, capitale giudicale. is st. medioevale, 15-20. plint a.g., eyles n., eyles c., walker r.g., (1992) control of sea level change. in walker r. & james n. eds., facies models: response to sea level change,15-25. pomesano cherchi a.,(1971) studio stratigrafico e micropaleontologico del pozzo oristano 1 (sardegna). memorie della società geologica italiana, 10, 1-16. ulzega a., ozer a., lecca f., leone g. pecorini c., spano c. & cordy m.j., (1982) excursion tableronde tyrrhenian de sardaigne. inqua, 88 pp. ulzega a. & hearthy p.j., (1986) geomorphology, stratigraphy and geochronology of late quaternary marine deposits in sardinia . z.geomorp., n.f.suppl. bd., 62, 119-129 walker m., (2005) quaternary dating methods, john wiley & sons, 187 pp. imp.palmentola&lazzari proposal for a thematic itinerary on geomorphological sites along the western coast of the salento peninsula, southern italy giovanni palmentola1 & maurizio lazzari2 1università degli studi di bari dipartimento di geologia e geofisica, via orabona 4, bari g.palmentola@geo.uniba.it 2c.n.r.i.b.a.m., sezione di lagopesole, via federico ii, 85020 lagopesole (pz) lazzari@iisf.pz.cnr.it abstract: g. palmentola & m. lazzari, proposal for a thematic itinerary on geomorphological sites along the western coast of the salento peninsula, southern italy. (it isnn 0394-3356, 2005). researches carried out on the quaternary coastline modifications along the western salento peninsula of apulia, permitted to survey a succession of well-preserved geomorphological sites. these sites testify the events which interested the studied coastal sector during the quaternary time from mid-late pleistocene (mis 9?) to holocene (mis 1). the coastal sector of great landscape value, along which geomorphosites are exposed, is wide some kilometres from gallipoli town toward north as far as the punta d’alto lido promontory (locally known as the “broken mountain”). in particular, a series of landforms is exposed there, shaped by the sea and by sessile organisms which live along the sea cliffs, as well as by aeolian accumulation and deflation landforms. the variety of well-preserved and easy accessible landforms and their concentration in a not wide coastal sector constitute a good opportunity for both didactic and popularization of the processes which characterize the coastal dynamics, as well as the relative diagnostic elements. riassunto: g. palmentola & m. lazzari, proposta per un itinerario tematico attraverso siti geomorfologici lungo la costa occidentale della penisola salentina. (it isnn 0394-3356, 2005). nel corso di ricerche sulle modificazioni quaternarie della linea di riva lungo la fascia costiera della puglia, in corrispondenza della costa occidentale della penisola salentina è stata rilevata una successione di siti geomorfologici nei quali sono conservate chiare testimonianze degli eventi che, nel corso del quaternario dal pleistocene medio-superiore (mis 9?) all’olocene (mis 1), hanno interessato quel settore costiero. il tratto di pregio paesaggistico lungo il quale sono esposti i geomorfositi che si intende descrivere si estende per alcuni chilometri dalla città di gallipoli verso nord, fino al promontorio della punta d'alto lido (localmente nota come "montagna spaccata"). in particolare, lì é presente una serie di forme modellate dal mare e dagli organismi sessili che ne popolano le falesie, e di forme prodotte dalla deflazione e dall'accumulo eolico. la loro varietà, il buono stato di conservazione e la loro concentrazione lungo un settore poco esteso e facilmente percorribile fanno sì che tali siti costituiscano una opportunità per la didattica e la divulgazione dei processi che caratterizzano la morfogenesi costiera, come anche per l’individuazione dei relativi elementi diagnostici. keywords: southern italy, salento peninsula, late pleistocene, holocene, coastal geomorphology, sea-level change, geomorphosites. parole chiave: italia meridionale, penisola salentina, pleistocene superiore, olocene, geomorfologia costiera, variazione del livello del mare, siti geomorfologici. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 115-123 1. introduction during researches partly supported by the italian ministry of scientific research (murst cofin 1998 and cofin 2000) about sedimentological and morphological evolution of italian beaches, a revision of data previous surveyed (palmentola & fiore, 1985) has been realized concerning middle and late pleistocene holocene sea level highstands along the western coast of salento peninsula (southern italy). due to both its relative tectonic stability from late pleistocene to the present, and its well-preserved lithostratigraphic and geomorphological features specially along its rocky coastal cliffs, salento peninsula represents a good area for the study of past sea level changes. a series of interesting features can be observed in a small area between gallipoli town and punta d’alto lido promontory along the ionian coast of the peninsula, where some sea-level high stands and some associated dune belts are exposed. because of their cultural, scenic and scientific attributes these features can be identify as “geomorphosites”, as well as because of their good state of preservation, peculiarity and patrimonial value (as evidence of the landscape regional evolution and climate variations), the studied area could constitute an example-locality for coastal geomorphology and dynamics studies in southern italy. intense human activity, in addiction to weathering, is presently threatening these sites and hindering their use for scientific and educational purpose. so that, this paper represents a preliminary step for protection of geomorphological sites through a proposal to incorporate them into the italian inventory of geosites, and propose them as a didactic thematic path for educational aims. in this way geomorphological assets becomes a patrimonial and cultural asset easily comprehensible, accessible and useful for both specialists and general public. 2. geological setting the salento peninsula is the southernmost part of the apulian foreland of both the apennines and dinaric 116 g. palmentola & m. lazzari orogenic systems (fig. 1). the foreland is represented by the outer apulian platform consisting of a variscan crystalline basement covered by approximately 6 km of mesozoic carbonate sediments. between the oligocene and miocene the foreland was affected by extensional tectonics (cristofolini et al., 1985; sella et al., 1988), due to its progressive deformation connected with the lithospheric subduction (doglioni et al., 1994), which produced a landscape characterized by a set of carbonate ridges ("serre") alternating with depressed areas. discontinuous pliocene and lower pleistocene transgressive deposits (calcareniti di gravina and calcareniti del salento formations) accumulated on mesozoic substratum into structural depressed areas. the geological history of salento peninsula ends with the deposition of middle and upper pleistocene sandy-clayey calcarenite deposits and aeolianites either on the mesozoic basement or on plio-pleistocene units. the more recent deposit diffusely outcropping in the peninsula is the "sabbie a brachiopodi" formation referred to an indeterminate post-sicilian age (d'alessandro & palmentola, 1978; palmentola, 1987; d’alessandro et al., 1994). subsequently, other eustatic oscillations produced small and not much wide transgressions along the salento peninsula coastline leaving depositional evidences above all along the western slope. 3. geomorphological sites and thematic itinerary the thematic itinerary from gallipoli town as far as to punta d’alto lido cape towards north (fig. 2) permits to observe six different well-preserved sea level highstands. this last will be described according with an itinerary easy practicable along the main coastal route, starting from punta d’alto lido cliff and running towards gallipoli. the start-point (1st stop) is on the top of punta d’alto lido, on the left of the road to gallipoli, where 70m above s.l. an abrasion surface cut into mesozoic bedrock during early and middle pleistocene, is exposed. this surface is diffusely covered by “post-sicilian” sediments with terebratula scillae seguenza (“sabbie a brachiopodi” formation, d'alessandro & palmentola, 1978; d’alessandro et al., 1994) not older than mis 11, which represent the last wide marine transgression on the salento. with the subsequent regression the coastal zone of the peninsula reached approximately its present day contour being only partially modified, especially along its western side, by the following sea level fluctuations. the itinerary continues going down along a path until to 45-50 m above s.l. (2nd stop) where a successive sea level highstand is testify by a band of lithophaga boreholes and by thin well-cemented remains of a pebbly-sandy beach, in erosive contact on mesozoic limestone (melissano formation). chronostratigraphic position of this highstand can only be deduced from stratigraphic data: it is more recent and altimetrically lower than the "sabbie a brachiopodi" formation and older as well as higher than some calcarenites with strombus bubonius lamarck (mis 5e), both outcropping in the same area, along and near the same cliff. this means that this highstand is younger than mis 11or 9 and older than mis 5e. coming down along the same cliff the 3rd stop can be observed along a road trench, the “ broken mountain” trench (fig. 3). the walls of this road cutting show morphological and geological evidences of two other sea level highstands. the first is testified by a well-preserved notch with an associated some meters wide wave-cut platform at 15 m above s.l.. the second, fig. 1 geographic location and schematic geologic map of the studied area. legend: 1) sands and clays locally alternated with bioclastic deposits (pleistocene); 2) calcarenites (plio-pleistocene); 3) cretaceous limestones of mesozoic basement (melissano formation). ubicazione geografica e carta geologica schematica dell’area di studio. legenda: 1) sabbie ed argille localmente alternate a depositi bioclastici pleistocenici; 2) calcareniti (plio-pleistocene); 3) calcari cretacei del basamento mesozoico (formazione di melissano). by sediments accumulated during a brief successive sea-level rise, which buries all the signs of the previous one. this sediments, topping at about 22 m above s.l., are constitute by pebbles and calcarenite mudstones with marine fossils (patella sp.), and are bored by lithophaga. some continental clinostratified coarse breccias, about 1.5 m thick, interbedded with a darkpink, silty-sandy deposit cover all the marine deposits. because of the altitude this last palaeo-sea level is correlable to a hardy eroded and degraded dune belt (fig. 4), which base is at about 35 m above s.l., outcropping in the hinterland of gallipoli on the orographic right of 117proposal for a thematic itinerary ... the canali stream (fig. 2). both the two sea-level highstands of the 3rd stop seem to be referable to two main oscillations of mis 7, where the younger one (mis 7a) is more elevated than the older (mis 7c), as occurs in other places of mediterranean countryes (zazo et al., 1993; 1994) and as is also suggested by the oxygen isotopic curve of shackleton et al. (1990). starting from “broken mountain” and running about one hundred meters towards gallipoli until to lido delle conchiglie, the fourth stop (fig. 5) can be reached where, to the bottom of punta d'alto lido cliff fig. 2 thematic itinerary map along the geomorphological sites. legend: 1) main stops; 2) sea cave; 3) outcrops of calcarenite with strombus bubonius lamarck.; 4) dune belts; 5) saracen tower; 6) active quarry into dunes; 7) dune belts ridge; 8) itinerary; 9) railway; 10) main roads; 11) canali stream; 12) coastline. carta dell’itinerario tematico lungo i siti geomorfologici. legenda: 1) stops principali; 2) grotta marina; 3) affioramento di calcareniti con strombus bubonius lamarck.; 4) cordoni dunari; 5) torre saracena; 6) dune in cava attiva; 7) dorsale del cordone dunare; 8) itinerario; 9) ferrovia; 10) strade principali; 11) torrente canali; 12) linea di costa. 118 g. palmentola & m. lazzari f ig . 3 – r o a d c u tt in g t ra n sv e rs a l to p u n ta d ’a lt o l id o c lif f, w h e re m a ri n e c a lc a re n it ic m u d st o n e s (c a ) o u tc ro p i n e ro si ve c o n ta c t o n t h e m e so zo ic l im e st o n e s o f m e lis sa n o f o rm a ti o n ( m .f .) . t h e p a la e o s e a l e ve l, p ro b a b ly r e fe ra b le t o m is 7 a , is e vi d e n c e d b y a l it h o p h ag a b a n d ( l it h ) to t h e t o p o f p e b b ly c a lc a re n it ic m u d st o n e s (c a ), o b se rv a b le o n t h e l e ft o f p ic tu re . t h e se d e p o si ts c o ve r a lo w e r a n d n o t w e ll p re se rv e d n o tc h a n d t h e a ss o c ia te d w a ve -c u t p la tf o rm ( th ic k b la c k lin e ) te st ify in g a n o ld e r se a le ve l h ig h st a n d ( m is 7 c ? ). a ll th e s u c c e ss io n p a ss e s u p w a rd t o c lin o st ra ti fie d c o n ti n e n ta l b re c c ia s (b r) . t ri n c e a st ra d al e t ra sv e rs al e a lla f al e si a d i p u n ta d ’a lt o l id o , d o ve a ff io ra n o f an g h i c al c ar e n it ic i ( c a) in c o n ta tt o e ro si vo s u l s u b st ra to m e so zo ic o d e i c al c ar i d i m e lis sa n o ( m .f .) . il p al e o li ve llo d e l m ar e , o ss e rv ab ile s u lla s in is tr a d e lla f ig u ra , è p ro b ab ilm e n te r ife ri b ile a l m is 7 ° e d è e vi d e n zi at o d a u n a fa sc ia d i f o ri d i l it o fa g i p o st a al t o p d e lle c al c ar e n it i c io tt o lo se ( c a) . t al i d e p o si ti c o p ro n o u n s o lc o d i b at ti g ia e la r e la ti va n o n b e n c o n se rv at a p ia tt af o rm a d i a b ra si o n e m ar in a (li n e a n e ra ) p iù b as sa e p iù v e c c h ia , te st im o n ia n d o c o sì u n p iù v e c c h io a lt o s ta zi o n am e n to d e l l iv e llo d e l m ar e ( m is 7 c ? ). t u tt a la s u c c e ss io n e p as sa v e rs o l’ al to a d u n a b re c c ia c o n ti n e n ta le c lin o st ra ti fic at a (b r) . 119proposal for a thematic itinerary ... fig. 4 higher and older very degraded dune belt outcropping in the hinterland of gallipoli. cordone dunare degradato più alto e più vecchio affiorante nell’hinterland di gallipoli. fig. 5 aerial photo of lido delle conchiglie punta d'alto lido area. legend: 1) top abrasion surface with remains of “calcareniti del salento formation” (early pleistocene); 2) itinerary; 3) stops with meaningful outcrops of morphological and geological evidences of middle-late pleistocene sea level oscillations. ripresa aerea dell’area del lido delle conchiglie-punta d’alto lido. legenda: 1) superficie d’abrasione marina con lembi della formazione delle calcareniti del salento (pleistocene inferiore); 2) itinerario; 3) stops con i principali affioramenti di evidenze geologiche e geomorfologiche delle oscillazioni del livello del mare del pleistocene medio-superiore. 120 at 8 m above s.l., remains of a fourth highstand are well preserved (fig. 6). they are represented by a band of lithophaga boring the cretaceous limestones of the cliff, and by remains of a proximal pebbly beach deposit, laterally passing to sandy-calcarenite deposits with nests of strombus bubonius lamarck. this calcarenite, corresponding to mis 5e (“tyrrhenian phase”, mirigliano, 1956), can be altimetrically correlated with a thick and well-preserved sandy dune belt, with the base at 15-20 m above s.l., outcropping in the hinterland of gallipoli (fig. 2). these dunes are well exposed in a quarry and along a railway cutting (fig. 7) easy reachable running the road from gallipoli to alezio. the morphological effects of a successive 5th highstand can be studied along the coastal road between punta d’alto lido and gallipoli (5th stop) represented by a seaward surface wave-cut at about 2 m above s.l. into the calcarenites with strombus bubonius lamarck. the age of this abrasion event has been assigned to mis 5a (cotecchia et al., 1971) by mean of a sample of cladocora coespitosa (linnè) found in some coastal sediment over the calcarenites, which showed a radiometric age of 85 ka. this datum was afterwards corroborated by dai pra & hearty (1988; 1989) by means of isoleucine epimerization ratio of some helix sp. (70 ka) collected in a thin red soil level between the abrasion surface and an overlaying holocene yellowish dunes. this last situation is still exposed in the neighbourhood of torre sabea (6th stop), 1.5 km north of gallipoli, where a beautiful saracen watch-tower built of xi century is also observable (fig. 8). after the abrasion of the surface of 2 m a.s.l., a cold climatic phase (about 20 ka) induced a regression of sea-level towards the quaternary eustatic minimum of -120 m below its present position. this retreat was following by a rapid transgression, shown also in the holocene sea-level fluctuation curves reconstructed by dai pra & hearty (1989) and dini et al., (2000) for the coasts of southern apulia. the transgression ended about 6000-7000 years bp with the sea-level h i g h s t a n d c o r r e s p o n d i n g t o t h e p e a k o f m i s 1 (versilian transgression). this stage corresponds to the so-called “climatic optimum” (bertolani marchetti, 1985; rossignol-strick et al., 1992; yan & petit maire, 1994) and has been characterized by the warmest and most humid climatic conditions during the holocene (atlantic chronozone). the holocene yellowish dunes elongated roughly parallel to the present coast line, contain several pulmonate gastropods helix spp., radiometrically dated 6700-5300 yr b.p (cotecchia et al. 1969; hearty & dai pra, 1989; dini et al., 2000), have their base here and there submerged and are in many places partially covered or flanked by subactual dunes. g. palmentola & m. lazzari fig. 6 outcrops of pebbly beach and calcarenites deposits (pbd) at the bottom of the "broken mountain" cliff and in a sea cave, in erosive contact on mesozoic basement (melissano formation, mfm). laterally this deposit, corresponding to sea level highstand of mis 5e, grows thin as far as to be replaced by an abrasion marine surface (black striped area). affioramenti di spiaggia ciottolosa e depositi calcarenitici (pbd) nella parte alta della falesia della “montagna spaccata” in una grotta marina, in contatto erosivo sul substrato mesozoico (formazione di melissano, mfm). lateralmente questo deposito, corrispondente allo stage 5e, si assottiglia fino ad essere sostituito da una superficie di abrasione marina (area tratteggiata in nero). 4. conclusions the sites above outlined seem important to be preserved because of the rare and great value evidences they show. it is not usual to find in a relative small area such an important succession of geological and geomorphological events, testifying sea level variations fundamentally due to climatic changes occurred from the mid-pleistocene to holocene. in figure 9 such events are summarized by means of two ideal geomorphological profiles crossing the different landforms and deposits described in the main five stops. in short, after the deposition of the post-sicilian sabbie a brachiopodi formation, six eustatic oscillations produced between 45-50 m and 2 m above s.l. morphological and geological evidences of as many highstands, referable to mid-late pleistocene (mis 11 or 9?, 7c, 7a, 5e and 5a) and holocene (mis 1). 4.1 protection and valorization of geomorphosites all the geological and geomorphological evidences represent an irreplaceable scientific, didactic, environmental and cultural heritage and therefore an added value for this territory, which we believe must be preserved. unfortunately the sites are today seriously threatened by modifications and obliteration due to the anthropic aggression, as quarries in the sandy dune belts, road cuttings, urbanization and other human interventions. their protection is necessary because, with respect to a cultural asset strictu sensu, geomorphosites are not restorable and reproducible. different ways to opposite against their irreversible deleting and submitting the sites to active and pas121proposal for a thematic itinerary ... fig. 7 outcrop of sandy dune belt (db) some meters thick in a railway cutting in the hinterland of gallipoli. the photo shows also the classic curve shape of the dune belt with the axis elongated perpendicularly to the cutting. affioramento del cordone dunare sabbioso (db) spesso alcuni metri in corrispondenza di una trincea ferroviaria nell’hinterland di gallipoli. la foto mostra inoltre il classico profilo curvilineo della duna con l’asse allungato perpendicolarmente alla trincea. fig. 8 the figure evidences the outcrop of the calcarenite with strombus b. lamarck. (castb) near torre sabea, on which an evident and wide wave-cut platform at 2 m a.s.l. was shaped probably during the mis 5a. subsequently, a holocene dune belt with helix sp. was deposited on the same wavecut platform. la figura evidenzia l’affioramento della calcarenite con strombus b. lamarck. (castb) nei pressi di torre sabea, sulla quale si è modellata una evidente ed estesa superficie d’abrasione marina posta a 2 m s.l.m. e probabilmente riferibile allo stage 5°. successivamente un cordone dunare con helix sp. si è depositato su tale piattaforma. sive protection could be adopted. a first conservation strategy (sensu reynard, 2003), could be to propose their inserting in an inventory catalogue of the italian geotopes, binding the sites in order to submit them to active protection limiting the human activity. the itinerary along the main proposed stops should be insert in a context of tourist and educational flow, valorizing still more their scientific and didactic great value also by means of showcases, in which geomorphological landscape evolution during last different climatic phases would be schematically represented and explained. acknowledgements this work has been partially supported by the murst-cofin2000 project (national scientific coordinator: prof. g. fierro university of genova; local scientific co-ordinator: prof. g. palmentola university of bari). the authors warmly thank antonio cendrero and emmanuel reynard for their useful suggestions, critical reading and improvement of the manuscript. references bertolani marchetti d. 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(1985) character of the stress field in the calabrian arc and southern apennines (italy) on deduced by 122 g. palmentola & m. lazzari fig. 9 – geomorphological schematic profile along the main stops of the thematic itinerary from lido conchiglie-punta d'alto lido cliff to gallipoli-torre sabea, in which the more meaningful outcrops of sea level high stands and marine landforms are represented. in a) it is represented the situation of torre sabea (stop 5), while in b) the morphological and geological evidences observable in other three stops (projected from south) are shown. legend: 1) holocene dune belt (mis 1); 2) continental clinostratified breccias; 3a) coarse pebbly and calcarenitc beach deposits (mis 5e); 3b) calcarenites with strombus bubonius lamarck. (mis 5e); 4) calcarenitic mudstones with lithophaga band to the top (mis 7a); 5) pebbly beach and calcarenites remains (mis 9?); 6) cretaceous limestones. profilo geomorfologico schematico lungo i principali stops dell’itinerario tematico dalla falesia di lido delle conchiglie-punta d’alto lido a gallipoli-torre sabea, in cui vengono rappresentati gli affioramenti più significativi delle forme marine e degli alti stazionamenti del livello del mare. in a) viene rappresentata la situazione di torre sabea (stop 5), mentre in b) sono mostrate le evidenze geomorfologiche e geologiche visibili in altri tre stops (proiettati da sud). legenda: 1) cordone dunare olocenico; 2) brecce continentali clinostratificate; 3a) depositi di spiaggia calcarenitici e ciottolosi (mis 5e); 3b) calcareniti con strombus bubonius lamarck. 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(1985) inquadramento geografico e morfologico del salento. in: c. battista, f. boenzi, s. fiore, d. novembre, g. palmentola & l. pennetta (eds.), lineamenti geografici del salento leccese, conv. annuale gruppo nazionale di geografia fisica e geomorfologia, lecce, 41 pp. panizza m. (2001) geomorphosites: concept, methods and examples of geomorphological survey chinese science bullettin, 46, suppl. bd., pp. 4-6. reynard e. (2003) geosite in: a. s. goudie (ed): encyclopedia of geomorphology, london, routledge, pp. 440. rossignol-strick m., planchais n., paterne m. & duzer d. (1992) vegetation dynamics and climate during the deglaciation in the south adriatic basin from a marine record. quarter. sci. rev., 11, pp. 415423. shackleton n.j., berger a. & peltier w.r. (1990) an alternative astronomical calibration on the lower pleistocene time scale based on odp site 677 trans. r. soc. edinburgh, earth science 81, pp. 251-261. sella m., turci c. & riva a. (1988) sintesi geopetrolifera della fossa bradanica (avanfossa della catena appenninica) memorie società geologica italiana, 41, pp. 87-107. yan z. & petit maire n. (1994) the last 140 ka in the afro-asian arid-semiarid transitional zone paleogeogr.paleoclim.paleoecol., 110, pp. 217233. zazo c., goy j.l., dabrio c.j., bardaji t., somoza l. & silva p.g. (1993) the last interglacial in the mediterranean as a model for the present interglacial global and planetary change 7, pp. 109117. zazo c., goy j.l., hillaire-marcel c.l., dabrio c.j., hoyos m., lario j., bardaji t., somoza l. & silva p. (1994) variaciones del nivel del mar: estadios isotopicos 7.5 y 1 en las costas peninsular (s y se) e insulares españolas aequa, monografias 2, pp. 26-35. 123proposal for a thematic itinerary ... imp.cardara& geomorphological changes due to human actions at coppa nevigata (tavoliere di puglia, southern italy) reconstructed through core analyses massimo caldara1, ilena caroli2 & oronzo simone1 1dipartimento di geologia e geofisica, sezione di geografia fisica e geomorfologia – università degli studi di bari, campus universitario, via orabona 4, 70125 bari, italia; 2dottorato di ricerca in geomorfologia e dinamica ambientale – università degli studi di bari correspondence should be addressed to massimo caldara: caldara@geo.uniba.it abstract: m. caldara et al., geomorphological changes due to human actions at coppa nevigata (tavoliere di puglia, southern italy) reconstructed through core analyses. it issn 0394-3356, 2004 the area surrounding the coppa nevigata settlement is one of the best places for the reconstruction of the relationship between human activities and the environment since the first tavoliere di puglia population phases. the settlement is the best studied in the tavoliere plain, it is situated between the foot of the gargano headland and the inner shore of the ancient salpi lagoon, in a very sensitive area from the environmental point of view. previous studies highlighted the environment evolution and its chronology. the close relationship between the wet area facing the settlement and the population pattern in some cases was documented. the preliminary study of six new cores and considerations made on three previously drilled successions are the base of this research. the studied successions were grouped in three transects and described in function of their distance from the settlement. these are the a (distal), b (in the middle) and the c (proximal) transects. there were recognized eight different phases attributable to two different evolutionary patterns. the environments set under or modified by intentional anthropic action, such as the b (terrestrial phase i), d (terrestrial phase ii) and h (historical reclamation) phases, have to be ascribed to the first one. the almost "natural" phases belong to the second one, even if the accumulated material is often related to human actions. these are the phases a (natural phase i), c (natural phase ii), e (natural phase iii), f (arid terrestrial phase) and g (natural phase iv). the b and d anthropic phases have been recognized beneath the ground surface up to about 90 m far from the nearest exploration ditches dug by archaeologists on the side of the coppa nevigata knoll. we were not able to put a boundary between these two phases within the c transect cores, but they are well defined in the a transect. the anthropic phase b corresponds to an urbanization phase that seems to have been started from the most internal settlement areas through the artificial compaction/leveling of marshy/lagoonal deposits, whereas the presence of hearths in distal areas could be attributed to activities carried out outside the defensive wall system. the anthropogenic d phase shows, in the area next to the hillock side, the presence of simple inhabitation structures that lasted for a relatively long time, as testified by numerous tramped and/or leveled surfaces (simple or superimposed) associated to concotto levels and hearths. on the other hand in distal areas the d phase seems to be characterized by an agricultural/pastoral land use. the h phase sediments have locally accumulated under nearly natural conditions, even if they are directly related to reclamation works made during the last two centuries. in conclusion, through time man modified and shaped the environment around the coppa nevigata knoll, in particular during the middle bronze age (b phase), the iron age (d phase) and during the last two centuries (h phase). sometimes the sedimentation processes under natural conditions were also strongly influenced by man, as suggested by the presence of the organic deposits accumulated during the a phase or by the c phase sediments. riassunto: m. caldara et al., variazioni dell’ambiente geomorfologico indotte dall’uomo desunte dallo studio di carotaggi a coppa nevigata (tavoliere di puglia). it issn 0394-3356, 2004 l’area a ridosso dell’insediamento preistorico di coppa nevigata è quella che meglio si presta per la ricostruzione dei rapporti intercorsi tra l’uomo e l’ambiente a partire dalle prime fasi di popolamento del tavoliere di puglia. difatti, questo insediamento è certo quello più studiato del tavoliere ed inoltre era collocato ai piedi del promontorio del gargano sul margine interno dell’antica laguna di salpi, in un’area ad alta sensibilità ambientale, in quanto soggetta alle rapide modificazioni dovute alla combinazione di processi diversi (fluviale, marino, eolico ecc.) e all'opera dell'uomo. studi precedenti degli autori hanno delineato l’evoluzione degli ambienti e la loro collocazione cronologica. inoltre, in alcuni casi hanno messo in evidenza la stretta correlazione fra l’area umida antistante l’abitato di coppa nevigata e le modalità di vita e di sviluppo dell’insediamento. lo studio preliminare di sei nuove perforazioni, realizzate ad hoc a ridosso della collina di coppa nevigata, unito ad altre tre fatte precedentemente, è alla base del presente lavoro. le successioni sono state riunite in tre gruppi e descritte in funzione della loro distanza dall’insediamento (transetto a, distale; transetto b, intermedio e transetto c, a ridosso della collina di coppa nevigata). sono state riconosciute otto diverse fasi riconducibili grosso modo a due differenti modelli evolutivi. al primo appartengono gli ambienti originatisi o rimodellati intenzionalmente dall’uomo: fasi b (fase continentale i), d (fase continentale ii), e h (colmate storiche). al secondo appartengono gli ambienti dove il meccanismo di accumulo dei sedimenti è naturale, anche se molte volte i materiali accumulatisi sono riconducibili alle attività dell’uomo: fasi a (fase naturale i), c (fase naturale ii), e (fase naturale iii), f (fase continentale arida) e g (fase naturale iv). le fasi antropiche b e d che non si riescono a differenziare nelle successioni del gruppo c, quelle a ridosso dell’insediamento, e che sono ben separate nelle successioni del gruppo a, si ritrovano fino a circa 90 metri dai più vicini saggi archeologici. la fase antropica b corrisponde ad una fase di urbanizzazione che sembra procedere a partire dalle aree più prossime all’insediamento compattando i depositi palustri e/o lagunari con battuti, mentre nelle aree più lontane l’attività, limitata a soli focolari, sembra quella svolta all’esterno delle mura. la fase antropica d mostra, nell’area a ridosso della collina di coppa nevigata, la presenza, più o meno continua nel tempo, di strutture abitative semplici (abbondanza di battuti singoli e/o sovrapposti uniti a livelli di concotto e a focolari), mentre per le aree distali mostra una utilizzazione di tipo agricolo-pastorale. la fase antropica h è riconducibile alle colmate storiche degli ultimi secoli. si tratta di un deposito realizzato con intenzionalità dall’uomo anche se i meccanismi di sedimentazione sono praticamente naturali. in definitiva nell’area di coppa nevigata l’uomo ha rimodellato e modificato il paesaggio più volte, durante il bronzo medio (fase b), l’età del ferro (fase d) e negli ultimi due secoli (fase h). comunque è stato fortemente attivo condizionando la sedimentazione anche nella fase a con depositi organici, e nella fase c. keywords: buried morphology, geoarchaeology, tavoliere di puglia, holocene. parole chiave: morfologie sepolte, geoarcheologia, tavoliere di puglia, olocene. il quaternario italian journal of quaternary sciences 17(2/2), 2004, 495-508 496 m. caldara, i. caroli & o. simone 1. introduction the coppa nevigata settlement is one of the best known archaeological sites in the apulian region. it is located at 41°33’26”n, 15°50’00”e, some five kilometres from the modern coast, between the gargano promontory and the tavoliere plain. the site was situated on the inner shore of the holocene salpi lagoon (boenzi et al., 2001), a coastal waterbody extended from south of manfredonia to the ofanto river delta and now totally disappeared because of both natural infilling and land reclamation works (boenzi et al., in press; caldara et al., 2002b). the archaeological site is known since the first years of the xx century (mosso, 1909). nevertheless, it was subjected to systematic archaeological explorations only from the '50s of last century (puglisi, 1955; 1975; 1982). the investigations started again in 1983 with extensive excavations still in progress (cazzella & moscoloni, 1988; 1990; cazzella et al., 2001). the archaeological research evidenced a complex stratigraphy spanning from the early neolithic, throughout the bronze age and into the iron age (cazzella, 1996; cazzella & moscoloni, 1999). during the various inhabitation phases the mode of occupation changed (caldara et al., 2003a). since the '90s the authors have been investigating the coastal plain of the tavoliere, but the choice to focalise the multidisciplinary efforts in a sample area occurred only later. the coppa nevigata settlement offered good research possibilities, since the good knowledge acquired through decades of archaeological study as well as its location in a high sensitive environmental frame. the best available information suggests that the population around the lagoonal area increased and decreased several times. one explanation of this is past changes in the regional environmental conditions (boenzi et al., 2001; caldara et al., 2002b). in 1997 five cores were drilled (cn1 to cn5) at various distances from the settlement (fig. 1). the fig. 1 location of the studied areas. cnn = coring site. ubicazione dell’area. cnn = posizione dei sondaggi. study of two of the nearest cores to the site (cn2 and cn5) is by now complete (caldara et al. 1999; 2001; 2003b; in press c), while the most distant ones (cn3 and cn4) are still under examination (simone 2003; caldara et al., in press c). the first results obtained were the reconstruction of the environment evolution close to the site (caldara et al., 1999; 2001) and the understanding of chronology of the events (caldara et al., 2003a). the idea at the base of our research were that there was a close relationship between the wet area facing the coppa nevigata knoll and the way in which the settlement developed (caldara et al., 2002a). this connection has been documented in various cases. as an example, at the site were found ceramic artifacts, dating back between the proto-apennine and the subapennine periods, containing tephra (levi et al. 1999). the use of pyroclastic material as a tempering ingredient to make ceramics was possible by the presence of this kind of sediments in the lagoon bottom (caldara et al., 2001). an other example is the use of the cockle cerastoderma glaucum as a food resource, in particular during the neolithic and the bronze age (late subapennine), as documented by minniti (1999). as the study progressed we realized that, especially during the middle bronze age, man influenced the local environment evolution (caldara & simone 2003; in press), as attested by the presence of deposits directly related to anthropogenic activities only within the cores nearest to the settlement. the aim of this research is to asses how strong was the impact of human actions on the surrounding environment. one of the possible ways to reach this goal was the detailed reconstruction of the geometries of buried sedimentary bodies (both of natural and anthropic origin). to verify our hypotheses, six new cores were drilled in 2002 (cn11 to cn16). the coring locations were accurately decided on a detailed map (fig. 1), in order to get a good distribution of samples. thus, at the base of this paper are the preliminary results of the study of the six new cores plus the cn1, compared and integrated with data obtained by the analysis of cn2 and cn5 successions. 2. geological and morphological setting the coppa nevigata knoll is situated along the south-east transition area (fig. 2) between the smooth limestone surface of the southern gargano terraces area, called "pedegargano" by caldara & palmentola (1991), and the alluvial coastal plain of the tavoliere di puglia (southern italy). the gargano is a calcareous massif, part of the mesozoic apulia platform. the outcropping rocks in the southern area of the headland are the oolithic, pseudooolithic, detritic and micritic limestone of the portlandian, "calcari oolitici di coppa guardiola" formation (luperto sinni & masse, 1986). in particular, the lower terrace at the foot of the headland, dips gently eastward starting from elevations slightly above 100 meters a.s.l.. the sub-horizontal surface, in correspondence of the terminal section of the candelaro stream, has been divided in several minor block by nw-se faults. 497geomorphological changes ... the tavoliere plain subsoil is made of a thick succession of quaternary terrigenous sediments overlaying the bradanic cycle deposits, in particular the "argille subappennine" formation. starting from the end of the lower pleistocene, due to some stands of the regional uplift combined with glacio-eustatic movements, the tavoliere landscape was shaped in a number of marine terraces gently sloping down towards the sea. some of them are now covered by broad alluvial deposits (caldara & pennetta, 1993a). during the last glacial phase, because of the lower sea level, the tavoliere coastland was deeply incised by rivers flowing from the apennine chain (caldara & pennetta, 1996; caldara et al., 2002b). at the end of the last glacial phase, the eastern margin of the tavoliere took the characters of a submergence alluvial plain coast. as the sea level raised, several lagoons set on the margin of the submerging plain. time after time, the eastern area of the tavoliere was then characterized by a variety of transitional environments, such as dune belts, lagoons, swamps and a broad alluvial coastal plain. in correspondence of the breaks of slope between the gargano and the pedegargano areas and between the pedegargano and the tavoliere plain, in particular at the mouths of the streams flowing down the headland, a number of alluvial fans developed during low sea level periods. these are broad sedimentary bodies made of limestone breccias whose rounded elements are well cemented in a calcareous matrix (boenzi & caldara, 1999). during the middle-late holocene a broad coastal lake set up, the salpi lagoon (caldara et al., 2002b). through its history, this lagoon underwent many changes in its shape and extent. nearly at the end of its existence, the coastal waterbody became a marshy and unhealthy land. recently, in particular during the last two centuries, the coastal plain was subjected to reclamation. in fact, several streams have been diverted in order to facilitate the infilling of coastal depressions, such as the versentino and salso lakes. as a result, the alluvial sediments covered and concealed all the features that characterized the coastal plain, including the deposits of lagoon-sabkha environments (studied by caldara & pennetta, 1993b and boenzi et al., 2001), the dune belt that separated it from the sea (schmiedt, 1973) and the historical lake deposits. nowadays an enclave of the ancient lagoon exists, this is the palude frattarolo (caldara et al., 1994), a broad coastal swamp situated south of manfredonia, between the coppa nevigata knoll and the coastline. 3. results acquired since former works so far in the coppa nevigata area four cores were studied (caldara et al., 1999; 2001; 2003b; in press c; simone 2003). two of those, the cn2 and cn5, were drilled in vicinity of the archaeological site, next to the lagoon shore. the other two bore holes, cn4 and cn3, were respectively made at 0.4 km and 0.8 km far from the settlement, towards the middle of the basin. the drillings at the foot of the settlement went across to sediments accumulated between before 3600 yr bp ("avellino eruption" tephra) and recent times. a stop in 498 m. caldara, i. caroli & o. simone f ig 2 s c h e m a ti c g e o m o rp h o lo g ic a l m a p . k e y to s ym b o ls : 1 = l im e st o n e d e p o si ts ( m e so zo ic ), p lio -p le is to c e n e c a lc a re n it e a n d q u a te rn a ry s lo p e d e p o si ts ; 2 = t a vo lie re d i p u g lia t e rr a c e d d e p o si ts ( m a ri n e a n d f lu vi a l); 3 = p re se n t d a y sa n d ; 4 = h o lo c e n e a llu vi a l d e p o si ts ; 5 = h is to ri c a l r e c la m a ti o n s e d im e n ts ; 6 = a llu vi a l f a n ; 7 = b u ri e d d u n e b e lt s; 8 = d o lin e ; 9 = e sc a rp m e n t d u e to m a ri n e a b ra si o n ; 1 0 = e sc a rp m e n t d u e t o f lu vi a l e ro si o n ; 1 1 = " v " sh a p e d f lu vi a l v a lle y; 1 2 = f la t b o tt o m e d f lu vi a l v a lle y; 1 3 = f o ss il d ra in a g e , p a la e o -r iv e rb e d ; 1 4 = d ra in a g e d it c h ( re a liz e d to r e c la im a n a re a b y d ra in a g e ); 1 5 = r o a d ; 1 6 = r a ilr o a d . c ar ta g e o m o rf o lo g ic a sc h e m at ic a. l e g e n d a: 1 = d e p o si ti c ar b o n at ic i m e so zo ic i, c al c ar e n it i p lio -p le is to c e n ic h e e d e p o si ti d i ve rs an te q u at e rn ar i; 2 = d e p o si ti t e rr az za ti m ar in i e f lu vi al i d e l t av o lie re d i p u g lia ; 3 = sa b b ie a tt u al i; 4 = a llu vi o n i o lo c e n ic h e ; 5 = c o lm at e s to ri c h e ; 6 = c o n o id e a llu vi o n al e ; 7 = c o rd o n i d u n ar i se p o lt i; 8 = d o lin a; 9 = s c ar p at a d i ab ra si o n e m ar in a; 1 0 = s c ar p at a d i e ro si o n e f lu vi al e ; 1 1 = in c is io n e a v ; 1 2 = in c is io n e c o n f o n d o p ia tt o ; 1 3 = d re n ag g io f o ss ile , p al e o al ve o ; 1 4 = c an al e d i b o n ifi c a; 1 5 = s tr ad a; 1 6 = f e rr o vi a. 499 deposition, highlighted by an erosive surface, occurred between the conventional 14c ages 2870±40 bp and 370±50 bp. in the middle of the basin (cn3 succession), at the bottom of the core, sediments have an age of 5580±40 yr bp. a hiatus is recorded between the conventional ages 3110±50 bp and 140±40 yr bp (caldara & simone, in press). materials found within the successions close to the settlement suggest the existence of a stable community in the nearby, particularly during the bronze age (caldara et al., 1999; 2001; 2003b). the cn2 and cn5 series show upcore alternating terrestrial and brackish horizons. one could interpret this alternation as the expression of four negative sea level fluctuations, marked by the deposition of terrestrial/marshy sediments (caldara & simone, in press). on the other hand, no evidence of sea level fluctuations were found in the middle of the basin (simone, 2003; caldara et al., in press c). according to caldara & simone (in press), three of the four fluctuations recognized in vicinity of coppa nevigata were most likely due to colonization of environments situated at the margin of the wet area, that is to say that the terrestrial/marshy environments should be considered as the expression of an aggrading coastline (whatever the cause) rather than a sea level fall. the analysis of the cn2 and cn5 cores made possible the reconstruction of palaeoenvironmental changes occurred in the nearby of the coppa nevigata settlement at least from 3600 years bp. on the basis of the fossiliferous assemblages, a descriptive name was given to each reconstructed environment (fig. 3). these, listed starting from the most ancient, are: 3.1. hydrobiidae spp. and cerastoderma lagoon mainly represented by clayey sediments, dominated by lagoon species, a few marine taxa occur in the lower section (caldara et al., 1999, 2001). during this first lagoon phase, two episodes conditioned the accumulation processes. the first event was the accumulation of a tephra layer containing materials from at least two different eruptions (caldara et al., 2001; 2003a). one of these has been identified as the "avellino eruption" of the vesuvius, dated at about 3500 ÷ 3600 bp (terrasi et al., 1999; albore livadie et al., 1998; rolandi et al., 1993; andronico et al., 1995). the rest of the tephra granules could be referred to one of the eruptions occurred during the last phase (4100 ÷ 3700 yr bp) of the phlegrean fields activity (caldara et al., 2001; 2003a). the second episode characterized the upper part of the hydrobiidae spp. and cerastoderma lagoon. at this level accumulated a horizon characterized by a high organic matter content, whose principal constituents are related to human activities, such as charred seeds and fruits, cereal remains, domestic animal bones, remains of insects living in granaries or breeding in decomposing meat and pottery fragments. given the excellent preservation state, we can say that these materials underwent a short transportation before the definitive deposition (caldara et al., 1999; 2001; 2003a). the accumulation of lagoon sediments continued until shortly after the radiocarbon date 3090±40 bp (cn5 core). 3.2. terrestrial phase i the successions continue upcore with sediments accumulated under sub-aerial conditions. the first centimetres are rich in organic matter and have a similar aspect in comparison to the ones above defined. the rest of the sub-aerial horizon is a soil made of siltyclayey sediment. the findings of pottery fragments, stones and concotto suggest that the settlement expanded towards the plain. according to the chronological data available, these structures were built after the radiometric date 3000±80 years bp and before 2870±40 bp (caldara et al., 1999; 2001; 2003a). 3.3. cerastoderma lagoon the terrestrial deposits are overlaid by grey clayey silts. the fauna, characterized by a low diversity, is dominated by cerastoderma glaucum (caldara et al., 2001; 2003a). 3.4. salt marsh i gradually, the lagoon environment evolved to a brackish marshy area. the lower part of this interval is characterized by clayey silts with thin arenaceous beds, whereas in the upper part there are calcareous lumps and thin black levels made of organic matter. this environment was described as a salt marsh (caldara et al., 2001; 2003a). 3.5. hydrobiidae spp. and abra segmentum lagoon the sediments that constitute this third lagoon episode are clayey silts with pebbles in its lower part, silts with thin black organic matter levels and calcareous lumps in the upper part. the macrofauna is represented mostly by lagoon taxa. progressively the environment underwent a relative lowering of the water level. 3.6. terrestrial phase ii this is a new terrestrial phase whose sediments are clayey silts dark-grey in color, with several thin organic matter levels and small calcareous lumps. the fauna is characterized by a mixed assemblage made of broken terrestrial mollusc shells and young individuals of lagoon species. 3.7. salt marsh ii this environment is represented by dark gray clayey silts with alternating calcareous levels. the mollusc fauna is poor and dominated by hydrobiidae, few young individuals of cerastoderma glaucum and abra segmentum also occur. 3.8. arid or semiarid terrestrial phase it is not clear yet when the salt marsh sediments stop to accumulate. in fact, these are cut by an erosive surface. a sub-aerial period, under arid or sub arid conditions, is testified by the formation of calcareous crust levels and lumps. 3.9. bithynia leachi and ovatella myosotis wetland shortly before the radiocarbon date 370±50 bp, the area at the foot of the coppa nevigata hillock was submerged by fresh water. the sediments accumulated in this interval are sandy silts rich of ovatella myosotis and bithynia leachi. geomorphological changes ... 500 m. caldara, i. caroli & o. simone f ig . 3 s tr a ti g ra p h ic c o rr e la ti o n s a m o n g t h e s tu d ie d c o re s. t h e a , b , a n d c tr a n se c ts a re p a ra lle l, w h ile t h e d a lig n m e n t is p e rp e n d ic u la r to t h e f ir st o n e s. b e si d e t h e t ra n se c ts , th e a h le tte rs r e fe r to t h e r e c o g n iz e d p h a se s, w h ile t h e t e rm in o lo g y u se d is t h e s a m e a s in li te ra tu re . c o rr e la zi o n i st ra ti g ra fic h e . s o n o d is e g n at i i tr an se tt i a ,b ,c p ar al le li fr a lo ro e d p e rp e n d ic o la re . s o n o r ip o rt at i a fia n c o d e i tr an se tt i le l e tt e re a -h ri fe ri te a lle f as i d a n c h e l a te rm in o lo g ia d e g li am b ie n ti c o m e d e fin it a in le tt e ra tu ra . 3.10. terrestrial phase iii the very upper part of the cn2 and cn5 cores is made of silty-clayey soil, densely laminated and scarcely pedogenized. the faunistic content, mostly terrestrial shell fragments, is scarce. 4. description of the studied successions for convenience the successions were grouped in three transects and described in function of their distance from the settlement. in particular, in the a group there are three successions drilled at the foot of the coppa nevigata knoll; the c group consists of four series sampled close to the settlement; in the b transect there are only two cores drilled in the middle between the a and c groups (fig. 1). 4.1. a transect cn13, cn2 and cn5 cores these three cores show a great lithological variability (fig. 3), due to the thick alternation of deposits accumulated in natural conditions or under the more or less direct anthropic influence. the environments formerly reconstructed for the cn2 and cn5 cores show a good mutual correspondence (caldara et al., 1999; 2001). on the other hand, only the lower and higher sections of the cn13 core could be correlated in a satisfactory way with the homologue environments reconstructed for the cn2 and cn5 cores. at the bottom, the cn2 and cn5 cores show lagoon deposits, mostly clayey (hydrobiidae and cerastoderma lagoon; caldara et al., 1999; 2001; 2003a; in press a). between 4.05 m and 3.60 m below m.s.l. (cn2 core) the accumulation of tephra deposits occurred (caldara et al., 2001; 2003a). in both the cn2 and cn5 cores the upper section of the hydrobiidae and cerastoderma lagoon and the lower part of the overlaying terrestrial sediments are characterized by the accumulation of an organic sediment, dark in colour, mainly made of heterogeneous material originated after the activities carried out at the settlement during the bronze age (caldara et al., 2001; 2003a; in press a). in the cn13 core the accumulation of this kind of sediments started under brackish conditions and continued in a paludal environment dominated by fresh water molluscs. the series continue upcore with terrestrial deposits (terrestrial phase i; caldara et al., 2003a). these sediment are clayey to sandy, grey or reddish-grey, with small calcareous lumps, calcareous crust fragments, pottery fragments and broken domestic animal bones (ox, pig, sheep, dog etc.). in the cn13 core, between 1.49 m and 1.29 m below m.s.l., there is a thin black horizon made of tiny charcoals. another charcoal level, about one centimetre thick, lies under a leveled surface1. concotto fragments, limestone and sandstone clasts have been found at several levels within the cn2 and cn5 successions. these findings were attributed to the remnants of a wall structure (caldara et al., 1999; 2001; 2003a; in press a). in the following section, up to the present day sea level, the sedimentation around the three bore holes occurred under different conditions. in particular, the sediment in the cn2 and cn5 successions is a lagoon clayey silt (cerastoderma lagoon, cn2 core, caldara et al., 2001; hydrobiidae lagoon, cn5 core, caldara et al., 1999). upcore the lagoon evolved to a more superficial environment in which accumulated clayey silt rich in organic matter characterized by young individuals of brackish taxa (salt marsh i in caldara et al., 1999; 2001; 2003a). the upper part of this section is again represented by lagoon clayey silt (cn2 core). the assemblages are dominated by lagoon taxa, the other accompanying species belong to the marine domain (hydrobiidae and abra lagoon in caldara et al., 1999; 2001; 2003a). on the other hand, the corresponding section of the cn13 core is characterized by sediments virtually similar to the ones that lay directly below, i.e. dark silt with dispersed calcareous crust fragments, charcoals and pottery fragments. between 0 m and 0.40 m circa above m.s.l. the successions recorded a new terrestrial phase (terrestrial phase ii, caldara et al., 2003a), with the accumulation of clayey to sandy silt. several organic levels and dispersed small calcareous lumps also occur. the assemblages are made of terrestrial mollusc fragments and young individuals of brackish taxa. some domestic and wild animal bones also occur (caldara et al., 1999; 2001). burnt bone fragments and marine gastropods have been found within thin dark levels in the cn2 core. the successions continue upcore with dark grey silt accumulated in brackish-marshy environments (salt marsh ii, caldara et al., 1999; 2001; 2003a). the fossil association is made of scarce brackish molluscs, foraminifers and ostracods. these sediments are cut by an erosive surface, marked in the cn2 and cn5 cores by a thick accumulation of a secondary calcareous crust, originated by groundwater evaporation. on the erosive surface lays a sandy silt deposit with fresh water fauna. the reconstructed environment is a marshland characterized by a variable fresh water covering (bithynia and ovatella wetland, cn2 core; bithynia wetland and ovatella wetland, cn5 core. caldara et al., 1999; 2001; 2003a). the very upper part of these three sequences is made of soil disturbed by the intense ploughing activities (terrestrial phase iii, caldara et al., 2003a). 4.2. b transect cn11 and cn1 cores in this group there are only two cores (cn11 and cn1, fig. 3). despite the care taken during coring activities, there have been two metres of sample loss in the cn1 core. thus we were able to correlate these successions only in a partial way. further data should be collected with additional cores. the lower part of the cn1 succession, is a greygreenish clayey sediment, somewhere sandy. there are scattered charcoals, calcareous crust fragments and domestic animal bones (sheep). between 2.50 and 2.00 501geomorphological changes ... 1 with "leveled surface" we mean a surface made regular by spreading of fine sediment, whatever it is (generally calcareous or clayey). the use to spread material in order to regularize the ground is well known to the archaeologists that worked on the coppa nevigata site. m below m.s.l. the sediment is dark, compressible and rich in vegetal detritus. in the whole this deposit is quite similar to the high organic deposit found in the cn2 and cn5 cores (caldara et al., 2003a). from the base of the cn11 core and above the two metres gap in the cn1, the two drillings went across to fine sediments, mostly clayey, greyish to dark, hardly stratified, deposited under the direct anthropic influence (scattered bone fragments, charcoals, bronze age pottery fragments). in three occasions the core sediments differ from the general pattern above described. in particular, at the bottom of the cn11 core, there is a rudite horizon made of heterogeneous materials, such as lithic fragments (limestone crust and siliceous pebbles), bones, pottery, terrestrial molluscs and charcoals. in the cn1 core, at circa 0.30 m above m.s.l., there is a reddish concotto horizon six centimetres thick. finally, in the cn11 core, at 0.70 m above m.s.l., a horizon made of calcareous crust fragments suggests the presence of a probable leveled surface. the two successions continue with a brown clayey soil with small lithic fragments. the upper part of this soil is deeply disturbed by ploughing. 4.3. c transect cn12, cn14, cn15 and cn16 cores in this group there are the successions drilled close to the settlement. the lower part of the sequence accumulated under mostly natural environments (lagoon, salt marsh and fresh marsh), the upper part is made of sediments deposited under the more or less direct anthropic influence. the cn16 core is the only one that reached the limestone substrate in this area. the transgression surface, cut on cretaceous limestone, is marked by holes made by marine molluscs and sponges and covered by a thin calcareous sand with marine shell fragments (ostrea, mytilus and pinna). rapidly, the assemblage becomes typically lagoonal (cerastoderma glaucum, abra segmentum, cyclope neritea and ammonia beccarii and haynesina germanica). the same fauna characterizes the overlaying clayey deposit. we considered natural the sediments accumulated at the base of the cn12 core (up to 1.22 m below m.s.l.). in particular, between the base and 1.66 below m.s.l., the sediments are silty with tiny vertical roots and characterized by lagoon taxa (abra segmentum, hydrobiidae, haynesina germanica and ammonia beccari). in the middle part of this section there are three volcanoclastic horizons (fig. 4d). the first one, the thicker, has a fairly regular base, whilst the contact between the other two and the sediment below is less evident. between the horizons with tephra some volcanic granules occur scattered within the sediment. the faunistic assemblages indicate a lagoon environment. between 1.40 and 1.22 m below the m.s.l. the sediment is silty-sandy. the collected fauna (mostly ovatella myosotis and truncatella subcylindrica) suggests a salt marsh environment with some fresh water input (occurrence of bithynia leachi). at the bottom of cn14 succession (fig. 4a) there is a yellowish sand level with cerastoderma glaucum, abra segmentum and hydrobiidae; several bithynia leachi also occur. a sharp contact separates the sand from a greyish clay layer accumulated in an almost natural environment. the clayey unit could be subdivided in three horizons. the lower and the upper ones are characterized by a thick lamination due to the presence of organic detritus (fig. 4e). the central part is made of massive clay with subvertical tiny roots. faunal assemblage is dominated by brackish organisms: ovatella myosotis and truncatella subcylindrica, some miliolids (quinqueloculina spp.). we interpreted this environment as a salt marsh. the natural deposit at the lower end of the cn15 succession is a silty sand made mostly by tephra granules mixed to lagoon molluscs (hydrobiidae and abra segmentum), foraminifers and ostracods. the upper part of the natural deposit is represented by a fine greygreenish sediment, slightly sandy, with fragments of reworked molluscs, perhaps accumulated in a marshy environment. the rest of the sequence accumulated under the more or less direct anthropic influence. in all the cores the contact between natural and anthropogenic sediments is sharp and occurs at similar elevations in the cn12, cn14 and cn15 series, while it is deeper in the cn16 core. the anthropogenic sediments are porous, dark grey, with scattered bronze age pottery fragments, concotto, lithic tools, domestic animal bones (sometimes burnt), marine shells (phyllonotus trunculus) and charcoals. the bedding planes are hardly visible, except when the drillings went across to black hearth material, concotto levels, tramping and/or leveled surfaces and structures in use for a considerable time span (fig. 4a). a number of leveled surfaces have been found in all the drillings in this group. these are well evident in the cn12, cn14 and cn15 cores, because realized with materials very different (in colour and nature) from the rest of core sediments. in some cases the surfaces were leveled by spreading a fine yellowish calcareous sediment, originated from the weathering of the mesozoic limestone that outcrop in the nearby area (fig. 4c). in other cases the material spread to create a plain surface is a clayey sediment with high carbonates content. several tramping surfaces lay around the same elevation. the deeper surface lays at 1.06 m below m.s.l. in the cn14 and cn15 cores (fig. 4f). there is, in the same two cores, another yellowish surface at 0.19 m above m.s.l., while in the cn12 and cn15 series, drilled at a greater distance, a leveled surface lays around 1.5 m above present day sea level. the upper part of the cn12 core (between 1.44 and 2.08 m above m.s.l.) and the middle of the cn14 core (between 0.17 and 0.49 m above m.s.l.) are characterized by two horizons with many superimposed thin levels, made of alternating fine yellowish and greyish sediments, charcoal levels, brown soil, concotto etc. (fig. 4b). we think that at those horizons the cores went across to structures in use for a long time span (e.g., a hut). on the other hand, in the cn16 core the leveled surfaces seem to have been realized with a different technique. in fact, these are just a few centimetres thick and realized with limestone, calcarenite, siliceous pebbles and calcareous crust fragments. the upper part of the cn12, cn14 and cn16 continue with a brown clayey soil with small lithic fragments deeply disturbed by ploughing. 502 m. caldara, i. caroli & o. simone 503geomorphological changes ... fig. 4 cn 14 core (a) and close ups of some cores (b-f): b = cn14 core, d phase, alternation of yellow and grey sediments used to level the ground, red concotto levels and black burnt hearth grounds; c = cn12 core, d phase, two beds, yellow and grey, of material spread to level the ground; d = cn12 core, a phase, silt with tiny vertical roots, lagoon taxa and volcanoclastic horizon; e = cn14 core, a phase; from the bottom: yellowish sand with lagoon fauna, thick lamination due to the presence of organic detritus and greyish clay (salt marsh); f = cn15 core, b phase, grey sediment spread to level the ground and a black horizon of burnt vegetal remains. except for the cn1, cn2 and cn5 cores, got by an hydraulic corer, all the other cores (among which the ones above) were obtained by a percussion drilling machine. carotaggio cn 14 (a) e particolari di alcune carote (b-f): b = cn14 perforazione, fase d, alternanza di piani battuti gialli e grigi, con livelli rossi di concotto e neri di suoli bruciati; c = perforazione cn12, fase d, due battuti giallo e grigio; d = perforazione cn12, fase a, limi con sottili radici verticali sormontati da un orizzonte vulcanoclastico caratterizzati da faune lagunari; e = perforazione cn14, fase a, sabbie giallastre con fauna lagunare sormontate da argille sottilmente laminate ricche di sostanza organica che passano ad argille grigie massicce con tracce di radici. l’ambiente delle argille è di salt marsh; f = perforazione cn15, fase b, piano battuto di colore grigio sormontato da un orizzonte di resti vegetali combusti. le carote cn1, cn2 e cn5 sono state ottenute con una macchina idraulica, per tutte le altre (tra cui quelle in figura) è stato utilizzato il metodo di carotaggio a percussione. 5. events reconstruction due to the elements collected after this study we can give a tentative reconstruction of the events at the foot of the coppa nevigata knoll. the events succession is described starting from the most ancient one (fig. 3). 5.1. a phase natural phase i the natural phase a is characterized by environments with different peculiarities, but under absent or minimal human influence. this phase has been recognized in almost all the successions, except for cn11 (that did not reach those levels) and cn1 (whose bottom is characterized by probably colluvial sediments). the cn16 core is the only one that reached the cretaceous limestone substrate and presenting evidence of marine sedimentation. above this episode and within the other drillings, the sediments are dominated by lagoon species. the lagoon environment in the external (distal) successions (a transect) is characterized by salinities ranging between 25 and 18‰ (after molluscan analysis). the correspondent section, in the internal (proximal) cores (c transect), drilled at higher elevations, seem to be conditioned by a lower salinity. all those lagoonal deposits can be related to the "hydrobiidae and cerastoderma lagoon" found in the cn2 and cn5 cores. the cores at the western end of the c transect (cn12 and cn14) show, above the lagoon sediments, salt marsh deposits. on the other hand, in the cn15 core the lagoon sediments are overlain by deposits accumulated in a dry environment at the edge of a fresh marsh. among the a transect drillings, pyroclastic deposits were found only in the cn2 core (caldara et al., 2001; 2003a), whilst in the c transect tephra are present in the cn12 (fig. 4d) and cn15 cores. tephra deposits have been found in marginal lagoon environments, within the proximal cores. the thickness of these deposits, as well as the depth, increases with the distance from the centre of the settlement. this should confirm what hypothesised in caldara et al. (2003a), that is there was first a phase of tephra accumulation due to direct fall on a large surface characterized by different environments, followed by erosion and secondary deposition in low areas. the organic deposit (caldara et al., 2001; 2003a, in press a) has been found in all bore holes in the a transect and in the deeper one in the b transect, while it is not present next to the settlement (c transect). the maximum thickness of this deposit occurs in cn13 core (a transect). at this point it looks more probable that the deposition of the organic horizon is due to washing processes acting along the slopes of the coppa nevigata knoll, rather than intentional accumulation of material dumped by man next to the lagoon edge (caldara et al., 2003a; in press a). in conclusion, in the natural phase a there are lagoon (hydrobiidae and cerastoderma lagoon), salt marsh (ovatella myosotis facies), paludal and colluvial deposits, with abundant input of sediments from the settlement. 5.2. b phase – terrestrial phase i this phase corresponds to the terrestrial phase i (caldara et al., 2003a) in the a transect cores and probably in the b transect and seems to start during the early sub-apennine (caldara et al., 2003a; in press a). the erosive surface that separates the a phase from the b phase sediments appears as sloping towards the middle of the lagoon except for the cn16 core, where a depression is outlined. actually, the cn16 core represents an anomaly; in fact, in this succession the pyroclastic horizon occurs in the b phase and not in the natural interval. this drives us to hypothesize that the area around the cn16 core, no longer lagoonal, were utilized by the coppa nevigata community from the cetina phase (recchia, 2002), or at least from the early bronze age (before the "avellino" event). the b phase is characterized by the occurrence of the first leveled surfaces (cn14 and cn15 cores, fig. 4f) and by a thick accumulation of burnt material (cn13 core). the end of the b phase is well identifiable within the distal cores (cn2 and cn5) because of the return of brackish conditions. in the other cores the b phase seems to be in continuity with the d phase. tentatively we put the limit between the b and d phases at the base of the yellowish tramping surfaces slightly above the sea level within the c transect cores, and at the base of a tramping surface laying at 0.82 m below m.s.l. in the cn13 core. 5.3. c phase natural phase ii at the moment the c phase has been recognized only for the distal cores (cn2 and cn5), while we hypothesize its continuity in the area around the cores of the b transect (fig. 3), this should be assessed by means of new drillings. in other words, the setting of the natural phase ii seems as occurred only in the northern part of the studied area, facing the present day coastline (fig. 1). the natural phase ii is characterized by the succession of three brackish environments, i.e. cerastoderma lagoon, salt marsh i and hydrobiidae and abra segmentum lagoon (caldara et al., 1999; 2001). these environments have been correlated to the hydrobiidae and cerastoderma lagoon, recognised in the middle of the basin (cn4 and cn3 cores; caldara & simone, in press). this phase occurred between the final bronze and a not well defined iron age (caldara et al., 2003a). 5.4. d phase – terrestrial phase ii in the distal area (a transect cores), the d phase corresponds to the terrestrial phase ii (caldara et al., 2003). this one represents a new phase of occupation of the areas freed by lagoon waters. the lagoon retreat seems to have been occurred because of natural causes (caldara & simone, in press). we do not know exactly when this phase developed, perhaps between the iron age and roman period (caldara et al., 2003a; in press a). the erosive surface that separates sediments pertinent to the c and d phases lays around 0 m in the distal area (a transect), whilst within the b and c transect cores, given the similar characteristics that sediments show, the limit between b and d phases is somewhat undefined. the d phase is characterized by a number of tramping/leveled surfaces. these can be single (cn15) 504 m. caldara, i. caroli & o. simone or superimposed, sometimes there is an alternation of tramping/leveled surfaces, concotto levels and burnt hearth grounds (cn12 and cn14, fig. 4b,c). as regards to the distal area (cn2 and cn5 cores), given the findings of burnt soils and domestic bone fragments, caldara et al. (in press a) hypothesized a pastoral-agricoltural land use. nevertheless, the evidence collected with this study suggests that, at the foot of the knoll, several simple inhabitation structures were in existence during the various occupation phases. 5.5. e phase natural phase iii the e phase has been identified only in the distal drillings (a transect) and corresponds to the salt marsh ii (caldara et al., 2003a). therefore, the recovery of natural environment seems has been occurred in the areas at the external margin of the settlement. the e phase sediments are cut in their upper part by an erosive surface. their chronological position is not well defined yet. in addition there were not found any anthropogenic indicators, therefore we think that, during the deposition of the e phase sediments, the coppa nevigata knoll was not inhabited. the more recent findings are vi century bc pottery fragments (pallottino, 1951); that could mean that the e phase sediments accumulated successively. 5.6. f phase arid terrestrial phase the f phase did not leave sediments; it is recognizable because of two elements, i. e. the erosive surface that cut the paludal deposits in all the distal cores (a transect) at different elevations and the presence of calcareous crusts and lumps (evaporite) in the upper part of e phase sediments. these features suggest a subaerial phase characterized by a marked pedogenesis. the thick calcareous crust indicates arid conditions lasting for a long span of time. that is why we called this phase "arid terrestrial". at the moment we are not able to say how long the terrestrial phase lasted and when the erosion occurred. the only chronological indication comes from the stratigraphic position of this event. 5.7. g phase natural phase iv the g phase corresponds, in the distal area (a transect), to the bithynia and ovatella wetland (caldara et al., 2003a). in the lower part of the g phase sediments the environment seems to be fairly brackish, whilst in the upper part the waterbody is exclusively conditioned by fresh water input. radiocarbon data, 370±50 yr bp (cn2 caldara et al., 2001) and 140±40 yr bp (simone, 2003), suggest that this wet area was set around the end of the middle ages. documentary data show that this wet area (part of salso and versentino lakes) reached its maximum development around the end of the xviii century (caldara et al., 2002b), after the ruinous floods of the cervaro and carapelle streams in 1795 (giustiniani, 1797 1805). 5.8. h phase – historical reclamation these sediments correspond to the terrestrial phase iii in caldara et al. (2003a). the h phase is well recognizable within the a and b transects, while is less apparent in the c transect because of a loss of sample occurred during coring operations. nevertheless, these sediments cover both e phase (natural wet area) and d phase sediments (anthropogenic). the accumulation of the h phase deposits occurred after reclamation projects carried out through the diversion of the candelaro stream. the very upper part of this interval is deeply disturbed by ploughing activities. 6. conclusions by this research, in the coppa nevigata area we reconstructed eight different phases grossly attributable to two different evolution patterns (fig. 3). the first one includes sediments intentionally accumulated or reworked by man. the latter includes deposits which sedimentation was basically driven by natural processes, even though materials accumulated are often directly due to man activities at the settlement. we ascribed to the "anthropogenic" pattern the b, d and h phases. the "natural" pattern includes the phases a, c, e, f and g. we found the anthropogenic sediments (b and d phases) underground, up to circa 90 m from the nearest trenches dug by archaeologists (fig. 1). these deposits were not found within the cn4 and cn3 cores, drilled respectively 400 and 800 m far from the settlement (caldara & simone, in press). on the contrary, the cn3 and cn4 cores show that the hydrobiidae and cerastoderma lagoon persisted without interruptions from the neolithic to the iron age (caldara et al., 2003b). therefore, we correlate the hydrobiidae and cerastoderma lagoon found in the cn3 and cn4 cores to the a, b, c, d and e phases identified close to the settlement. at the moment it is not possible to distinguish the limit between the anthropogenic b and d phases within the successions of the c group (next to the settlement), while these are well distinguishable in the distal a group. even though directly related to anthropogenic activities carried out at the settlement, we defined as "natural" the high organic content material included in the a phase. we consider these sediments as washed out along the side of the knoll and deposited in a hollow at its foot, instead of intentionally disposed by man in a dumping area. the developing of the b phase seems to have been started from the most internal settlement areas (cn14 and cn15 cores). this would be in accordance with a urbanization phase occurred within the perimeter described by joining the hypothetical buried parts of defensive wall found by geophysical analysis (fig. 1). on the other hand, the presence of hearths in distal areas (cn13) could be attributed to activities carried out outside the defensive wall system. as regarding the d phase (anthropogenic), by the study of the cn2 and cn5 cores (in the distal area) caldara et al. (in press b) assumed an agriculturalpastoral land use for those levels. after this study, given the presence of a number of single or multiple (superimposed) tramping/leveled surfaces in association with 505geomorphological changes ... concotto and hearths levels (cn12, cn14 and cn15), we can hypothesize, at least for the areas surrounding the settlement, the persistence of simple inhabitation/occupation units. the b and d anthropic phases recorded within the cn16 sediments are worthy of further analyses. in particular, the first consideration is that around the cn16 drilling site the colonization occurred earlier than other investigated places within the coppa nevigata area. in that case the first post neolithic occupation phases would be occurred at least starting from the early bronze age (before the "avellino" event) or perhaps from the cetina phase (recchia, 2002). in addition, the cn16 core suggests a use of the area outside the apennine defensive system (part of the wall has been found beneath the surface by geophysical surveys; fig. 1). the h phase considerably differs from the two above mentioned b and d anthropic phases. the h phase deposits accumulated after direct anthropic actions, even though sedimentation processes occurred under almost natural conditions. in fact, during the xix century, the candelaro and cervaro streams used to wander in the coastal plain without flowing into the sea through a defined mouth. as a result, great part of the tavoliere coastal area was marshy and unhealthy (caldara et al., 2002b). for this reason in that period challenging reclamation projects have been conceived (afan de rivera, 1838; 1845). to protect their fields from frequent floodings the landowners started to build embankments. subsequently, the candelaro and cervaro streams were partially (sometimes totally) diverted towards the hollows (surrounded by artificial dikes) in order to fill them by siltation. in particular, the candelaro stream was embanked and its mouth was progressively shifted downstream towards the middle of the former salso lake. as examples we quote here reclamation works made between the 1869 and the 1909 (pareto, 1865; historical maps by the italian military geographical institute), in 1939 (rotella 1984) and after the world war ii. by this study we described the evolutionary mechanisms, both anthopic and natural, that acted in the coppa nevigata area since the neolithic. nevertheless, several problems have to be fixed in the future. in particular we found that correlations among the group b cores are not reliable, thus should be useful to drill more cores around the cn1 site. the chronology of the b and d anthropic phases, well defined for the distal drillings, is not verified for those close to the settlement (c group) and raises perplexities among the archaeologists. in addition, the area around the cn16 core should be investigated, in order to verify the existence of an early colonization phase occurred outside the walls and define the limits of the bulge in the limestone substrate (fig. 3). an other arousing question is from where the coppa nevigata inhabitants supplied material used for ground leveling and to realize the tramping surfaces. in conclusion, it is apparent how man was able, through time, to modify the surrounding environment, in particular during the middle bronze (b phase), the iron age (d phase) and during the last two centuries. even when the accumulation of sediments occurred under almost natural conditions, anthropogenic activities conditioned the environment evolution, such as during the deposition of the high organic content sediments in the a phase and during the c phase. acknoledgements this study was made possible thanks to funding from the bari university research project “genesi ed evoluzione geomorfologica delle piane pugliesi e lucane”, led by prof. f. boenzi, and the bari university "dottorato di ricerca in geomorfologia e dinamica ambientale". we wish also to thank dr. giulia recchia for chronological attribution of the many pottery fragments found within the new cores and for the useful discussions about the anthropogenic sediments. references afan de rivera c. 1838 memoria su i mezzi di ritrarre il massimo profitto dal lago salpi, coordinando quest'impresa a quella piu' vasta di bonificare e migliorare la pianura della capitanata. stamperia e cartiere del fibreno, napoli. afan de rivera c. 1845 del bonificamento del lago di salpi coordinato a quello della pianura della capitanata. napoli, stamperia e cartiere del fibreno, 638 p. albore livadie c., mastrolorenzo g. & vecchio g. 1998 eruzioni pliniane del somma-vesuvio e siti archeologici dell’area nolana. in: guzzo p.g. peroni r. 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(ed.), magna grecia e mondo miceneo. nuovi documenti. atti xxii conv. studi magna grecia, taranto 7-11 ottobre 1982, 45-51. recchia, g. 2002 i siti costieri garganici e i loro rapporti transmarini tra eneolitico ed età del bronzo. in: "paesaggi d’acque" a cura di n. negroni capacchio, sorano-farnese 13-14 maggio 2000, 331-341. rolandi g., mastrolorenzo g., barrella a.m. & borrelli a. 1993 the avellino plinian eruption of sommavesuvius (3760 y. b.p.): the progressive evolution from magmatic to hydromagmatic style. journal of volcanology and geothermal research, 58, 67-88. rotella g. 1984 cinquant’anni di bonifica nel tavoliere. in: ciccone s. (ed.) cinquant’anni di bonifica nel tavoliere, 31-171, bastogi ed. foggia schmiedt g. 1973 contributo della fotografia aerea alla ricostruzione dell'antica laguna compresa fra siponto e salapia, arch. stor. pugl., 26, 159-172. simone o. 2003 evoluzione olocenica e dinamica ambientale delle piane costiere pugliesi. tesi di dottorato inedita. università degli studi di bari bari, 171 pp. terrasi f., campajola l., petrazzuolo f., roca v., romano m., brondi a., d’onofrio a., romoli m. & moniot r.k. 1999 datazione con la spettrometria di massa ultrasensibile di campioni provenienti dall’area interessata dall’eruzione delle “pomici di avellino” . in: albore livadie c. (a cura di), l’eruzione vesuviana delle “pomici di avellino” e la facies di palma campania. edipuglia, bari, 139146. 508 ms. ricevuto il 17 luglio 2004 testo definitivo ricevuto il 28 settembre 2004 ms. received: july 14, 2004 final text received: september 28, 2004 m. caldara, i. caroli & o. simone imp.parolo& studio integrato fito-geomorfologico di un sistema di rocce montonate serpentinitiche (campagneda, alpi retiche, sondrio) gilberto parolo1, alberto carton2 & augusto pirola1 1dipartimento di ecologia del territorio e degli ambienti terrestri. università degli studi di pavia; e-mail: parolo@et.unipv.it 2dipartimento di scienze della terra. università degli studi di pavia. e-mail: carton@unipv.it riassunto: g. parolo et al., studio integrato fito-geomorfologico di un sistema di rocce montonate serpentinitiche (campagneda, alpi retiche, sondrio). (it issn 0394-3356, 2005). scopo di questo lavoro è l’identificazione di relazioni ripetibili tra le geoforme e le comunità vegetali, al fine di sviluppare indicatori vegetazionali di forme del paesaggio e dei processi geomorfologici che le interessano. l’area di studio è localizzata nella fascia boreale superiore in val malenco (provincia di sondrio, alpi retiche). il gruppo di rocce montonate è scolpito su un substrato serpentinitico del mesozoico ed è marginato da una serie di depositi glaciali, espressione di tre piccoli apparati morenici frontali riconducibili alle fasi stadiali tardiglaciali. diciannove rilievi fitosociologici, analizzati con il programma syn-tax 2000 sono risultati ripartiti in 5 gruppi distinti. indici di ricchezza e di diversità specifica (shannon-weaver: h = -σi pi ln pi), di dominanza (simpson: λ = σi pi 2) e di equitabilità (pielou: j = h / hmax, dove hmax = ln n° individui) sono stati calcolati per ciascuno dei popolamenti rilevati con l’intento di dedurre informazioni sulla loro stabilità ecologica ed organizzazione strutturale. la datazione dei depositi glaciali posti a contatto e a margine delle rocce montonate, effettuata mediante il calcolo dell’innalzamento del limite delle nevi, ha permesso di attribuire, al substrato su cui sono scolpite le rocce montonate, un’età superiore ai 13.000 anni b.p. la distribuzione e la variabilità delle fitocenosi sono collegate alla esistenza di condizioni ambientali diversificate, correlate con l’andamento morfologico del substrato, che influenza la disponibilità idrica dei suoli, la distribuzione della copertura nevosa e gli effetti legati al vento. le comunità vegetali sono dinamicamente stabilizzate dalle condizioni climatiche ed edafiche estremamente selettive. tuttavia processi di ringiovanimento edafico innescano regressioni dinamiche nelle comunità vegetali, verificatisi probabilmente in occasione di manifestazioni meteorologiche intense, oppure in relazione alle profonde sollecitazioni meccaniche generate dai processi crio e/o termoclastici a cui sono sottoposti i substrati. si può comunque ipotizzare una potenzialità della vegetazione diretta, a lungo termine, verso la formazione di una brughiera extrasilvatica a rododendro (rhododendretum ferruginei). infine, la distribuzione a mosaico delle comunità vegetali, relazionabile alla presenza di microhabitat ripetitivi e collegati potenzialmente da relazioni seriali o catenali, evidenzia la possibilità di considerare il sistema di rocce montonate in oggetto un geosigmeto. abstract: g. parolo et al., phyto-geomorphological integrated study of a serpentinitic roches moutonnées system (campagneda, rhaetian alps, sondrio, italy). (it issn 0394-3356, 2005). the aim of this work is to identify repeatable linkages between landforms and diagnostic features of the vegetation, as a preliminary step in the development of phytoindicators for geomorphological forms and processes. the study area is located in the upper boreal belt of the malenco valley (sondrio province, rhaetian alps). the roches moutonnées consist of mesozoic serpentinitic substratum and are surrounded by a sequence of glacial deposits. this sequence represents the expression of three little terminal morainic ridges, belonging to the late glacial age. syn-tax 2000 was used to analyse 19 phytosociological relevés; a cluster analysis (group average, similarity ratio) and a metrical ordination (pcoa, chord distance), applied to all the relevés, pointed out the presence of 5 distinct groups. richness and diversity indexes (shannon-weaver index: h = -σi pi ln pi), dominance (simpson index: λ = σi pi 2) and evenness (pielou index: j = h / hmax, where hmax = ln n° individuals) have been calculated for all the plant communities, to look into their ecological stability and structural composition. we estimated the age of the glacial deposits, that surround the roches moutonnées, by using the raising of the equilibrium line altitude. this allowed to attribute more than 13.000 years b.p. to the substratum of the roches moutonnées. the distribution and variability of the phytocoenoses are linked to the existence of different environmental conditions, depending on geomorphological processes and forms of relief, that influence the water availability in the substratum, the snow cover and the wind effects. the extremely severe climatic and edaphic conditions stop the dynamic of the both plant communities of summits and interposed depressions. nevertheless processes of edaphic rejuvenation promote regressive events in the vegetation cover; this is probably related to intense meteorological processes or depends on deep mechanical stresses caused by cryoand/or termoclastic processes, that affect the substrata. we can, however, suppose that the potential expression of the vegetation could lead, in the long term, to acidocline alpenrose heaths (rhododendretum ferruginei). because of the mosaic distribution of plant communities, related to the repetitive presence of microhabitat and potentially linked by catenal and seral relationships, the roches moutonnées system can be considered a geosigmetum. parole chiave: studio fito-geomorfologico; vegetazione alpina; rocce montonate; depositi tardiglaciali; alpi retiche; fascia boreale superiore; substrati serpentinitici. keywords: phyto-geomorphological study; alpine plant communities; roches moutonnées; late glacial deposits; rhaetian alps; upper boreal belt; serpentinitic substrata. il quaternario italian journal of quaternary sciences 18(2), 2005 69-86 70 g. parolo, a. carton & a. pirola 1. introduzione la copertura vegetale e la forma del rilievo terrestre presentano spesso importanti e molteplici interazioni, specialmente in ambienti di alta montagna, ove tali rapporti risultano più evidenti (braun-blanquet, 1972; panizza, 1980; ozenda, 1985; ellenberg, 1988; körner, 1999). i fattori orografici, derivanti dall’andamento del rilievo, hanno un’influenza notevole sugli organismi vegetali, soprattutto perché sono in grado di influenzare l’espressione di altri fattori, quali quelli climatici. a sua volta la copertura vegetale influisce sia direttamente che indirettamente sulla morfogenesi, limitando ad esempio i processi erosivi dovuti all’azione dell’acqua e del vento, e figurando, specie se ben sviluppata, come causa ed indizio di stabilità morfologica. l’interazione vegetazione-geoforma è un processo analizzabile a differenti livelli di percezione fitoecologica, contraddistinti da gradi di complessità crescente: sinusie, fitocenosi e individui di geosigmassociazioni (gillet, 1985), possono essere utilizzati a varia scala per verificare il grado di fedeltà e la ripetitività dei rapporti con forme del paesaggio di diverso ordine di grandezza. negli ultimi decenni, accanto a studi volti ad indagare gli effetti dei processi geomorfologici sulla copertura vegetale in ambienti periglaciali, dal punto di vista ecologico e dinamico (giacomini & pirola, 1957; pirola, 1959; 1962; carbinier, 1966; klug-pümpel, 1982; richard, 1987; pirola & credaro, 1994; pirola et al., 1998; rossi et al., 1998; becker & dierschke, 2005), si sono sviluppati metodi di indagine, recentemente anche in ambito gis, che ricercano le relazioni spaziali di interdipendenza tra le forme del paesaggio e i syntaxa vegetazionali, con l’intento di individuare corrispondenze statisticamente ripetibili; le comunità vegetali diventano così indicatrici di determinate geoforme e/o di processi geomorfologici (delpech, 1985; gerdol et al., 1985; gerdol & smiraglia 1990; tomaselli & agostini, 1990; hoersch et al., 2002; kozlowska & raczkowska, 2002; bertin, 2003; cannone & gerdol, 2003; parolo, 2003; caccianiga & andreis, 2004); la loro aggregazione in unità superiori secondo relazioni di tipo dinamico o catenale, qualora l’unità si presenti fortemente eterogenea, rappresenta il primo livello di indagine nella descrizione del paesaggio vegetale (gehu & rivaz martinez, 1981; gehu, 1988; theurillat, 1992a), definibile soltanto attraverso l’identificazione delle unità elementari che lo costituiscono (ecotopi), confermate dalla ripetitività delle corrispondenze tra ambiente fisico e fitocenosi (pedrotti et al., 1997). il presente lavoro si propone di evidenziare relazioni ecologiche ripetibili tra geoforme e comunità vegetali in un sistema di rocce montonate serpentinitiche in ambiente alpino extrasilvatico, con lo scopo di individuare aree fito-geomorfologiche unitarie del paesaggio e di sviluppare indicatori vegetazionali di forme del paesaggio e dei processi geomorfologici che le interessano. le rocce montonate si possono annoverare tra le principali forme di erosione glaciale. si tratta di gobbe rocciose spesso associate in gruppi, frequentemente sagomate secondo la direzione di movimento del ghiacciaio, levigate sopra e sul lato rivolto contro il flusso glaciale, scabre sul lato sotto corrente. sono ben evidenti nelle attuali aree proglaciali ed osservabili in ambienti oggi prevalentemente sottoposti a processi crionivali o più generalmente ove vi sia stato il passaggio di un ghiacciaio. l’esarazione forma in genere, tra un dosso roccioso e l’altro, depressioni da sovraescavazione disposte sia in senso longitudinale sia in senso trasversale rispetto alla direzione del flusso glaciale. l’entità dell’erosione è in diretta relazione con le caratteristiche meccaniche della roccia e con la quantità di detrito trasportato dal ghiacciaio lungo l’interfaccia roccia/ghiaccio. le depressioni tra una roccia montonata e l’altra “catturano” spesso detrito fine, generato dai processi di degradazione, che funge da substrato per la vegetazione. nel sistema di rocce montonate studiato, situato sulle alpi retiche, si osserva che l’alternanza di dossi e di depressioni induce la formazione di un mosaico di condizioni micro-ambientali, variabili in modo repentino anche su spazi ridotti (fig. 1). le depressioni, scavate nella roccia, sono di norma caratterizzate da una saturazione idrica più o meno spinta dovuta alla permanenza prolungata del manto nevoso ed al ristagno di acqua, favorito dalla frazione pelitica presente, convogliata nelle depressioni dal ruscellamento nivale e dalle piogge. queste porzioni di terreno, a maggiore umidità, nelle stagioni intermedie gelano fino ad alcuni decimetri di profondità, rendendo superficialmente impermeabile il suolo. sui dossi, al contrario, i periodi prolungati di siccità e le basse temperature invernali, il cui effetto sulla componente biotica è aggravato dalla scarsa copertura nevosa, favoriscono lo sviluppo di comunità vegetali a struttura generalmente aperta, con adattamenti xeromorfi. 2. area di studio l’area di studio (fig. 2) è ubicata in val malenco nel piano di campagneda (provincia di sondrio) tra i 2200 e i 2310 m e comprende un sistema di rocce montonate modellate dal ghiaccio durante il tardiglaciale. i dossi montonati e le contigue depressioni da sovraescavazione si alternano con passaggi bruschi e repentini da una forma all’altra oppure possono essere collegati da superfici, più o meno estese, a dolce inclinazione (10°÷20°). esse sono scolpite nella formazione delle “serpentine della val malenco” fig. 1 le rocce montonate serpentinitiche oggetto della ricerca. the object of this research: the serpentinitic roches moutonnées. (aa.vv., 1970), rocce mesozoiche metamorfiche (serpentini e serpentinoscisti) con chimismo ultramafico. altre rocce montonate risultano modellate su ridotti affioramenti di rocce metamorfiche silicee, appartenenti alla formazione dei “micascisti del m.te acquanera”; su queste ultime non sono stati effettuati rilevamenti fitosociologici. il clima è di tipo temperato continentale; secondo la recente classificazione fitoclimatica di blasi (1996) può essere ascritto al termotipo alpino e all’ombrotipo ultraiperumido. le condizioni climatiche rigide dell’area, caratterizzate da basse temperature medie annuali, da accentuate escursioni termiche stagionali e giornaliere e da abbondanti precipitazioni nevose, sottopongono le rocce emergenti a processi degradativi provocati dall’alternarsi di fasi di gelo e di disgelo (gelifrazione), particolarmente efficaci in quanto favoriti dall’elevata scistosità, tipica delle rocce serpentinitiche. 2.1 studi geomorfologici precedenti non esistono approfonditi studi di geomorfologia che riguardano l’area in esame; la maggior parte dei lavori prende in considerazione gli aspetti geologici, soprattutto a scala regionale (benning & sidler, 1992). frammentarie notizie si possono ricavare da studi più generali sul glacialismo quaternario della val malenco e delle alpi insubriche valtellinesi. il primo lavoro che si può in un certo qual senso considerare di carattere geomorfologico risale al 1930 (nangeroni, 1930). nell’opera l’autore, sulla base delle morene “stadiarie”, ricostruisce i ghiacciai della val malenco, ne traccia i limiti e fornisce ai vari depositi una attribuzione cronologica. successivamente godenzi (1957) pubblica la sua tesi di laurea che riguarda la morfologia glaciale e la geomorfogenesi della valle di poschiavo. nel lavoro vengono fatti alcuni riferimenti alla zona di campagneda, senza però entrare nel dettaglio della morfologia. alcune informazioni sui depositi quaternari 71studio integrato fito-geomorfologico ... si possono ricavare invece dalla geologiche karte der bernina gruppe alla scala 1:50.000 (staub, 1946); in essa vengono cartografati con estremo dettaglio i depositi glaciali e gli argini morenici presenti nell’alpe di campagneda e nell’alpe di prabello. lo staub differenzia in questa zona tre unità glaciali. in un successivo lavoro venzo (venzo, 1971), pur tracciando un quadro completo ed estremamente articolato degli stadi tardowürmiani e post würmiani delle alpi insubriche valtellinesi, raramente fa specifico riferimento all’area oggetto del presente studio. 2.2 inquadramento vegetazionale la vegetazione dell'area di studio è compresa nella regione forestale endalpica (del favero, 2002), al di sopra dell’attuale limite superiore del bosco chiuso, collocabile mediamente attorno ai 2200 m. le fasce vegetazionali riconoscibili nel piano di campagneda sono la boreale superiore, caratterizzata da alberi isolati e da arbusteti nani o contorti fino a 2400 m, la fascia alpica in cui dominano le praterie naturali chiuse con presenze discontinue di tundra alpina, e infine la fascia nivale definita in base alla fisionomia discontinua della vegetazione erbacea (zolle aperte) progressivamente sostituita da comunità prevalentemente con strutture proprie degli stadi pionieri, su pietraie e rocce (tab. 1). in questi ambienti, durante le fasi iniziali, si riscontrano comunità vegetali caratterizzate dalla compresenza di specie acidofile e basifile, tipiche dei litotipi di natura serpentinitica. al di sotto dei 2000 m si esprime la pecceta subalpina (piceeion abietis), che viene sostituita più in altitudine da boschi aperti e luminosi di larice con sottobosco di ericacee e da arbusteti extrasilvatici (rhododendretum ferruginei), localmente interrotti da praterie secondarie pascolate (sieversio-nardetum strictae). tutta la fascia boreale superiore può essere considerata un ampio ecotono determinato dalla variazione altitudinale delle condizioni ambientali progressivamente più rigide che riducono o escludono i fattori favorevoli alle forme arboree e arbustive (“zona di contesa”). la vegetazione potenziale è la brughiera extrasilvatica di arbusti nani a rododendro e mirtillo (rhododendretum ferruginei), riscontrabile sulle rocce montonate localizzate in posizione marginale all’area di studio. la pastorizia, ancora attiva, ha modificato questo paesaggio con il decespugliamento e il pascolo, lasciando però frammenti di vegetazione naturale molto significativi per il riconoscimento dei limiti altitudinali che separano le fasce di vegetazione. nella fascia boreale superiore si trovano lembi di vegetazione idroigrofila, ascrivibile alle torbiere basse, situate in depressioni alimentate da acque superficiali o da sorgenti. inoltre in corrispondenza di limitate emergenze di calcari metamorfosati, vi sono frammenti di praterie basifile. la transizione alla fascia alpica è poco evidente per le modificazioni delle praterie alpine in pascoli dominati da nardus stricta ma, dove il disturbo è solo saltuario o assente, si trovano le praterie naturali tra cui quella considerata il climax alpino, il caricetum curvulae. la fascia nivale inizia all’altitudine di circa 2900 m, quota da considerare teorica per il fatto che la discesa a quote inferiori di pietraie a lungo innevamento determina frequenti enclavi extrazonali della vegetazione periglaciale (androsacetalia alpinae). fig. 2 l’area di studio si trova nel piano di campagneda (val malenco, sondrio), tra i 2200 e i 2300 m di altitudine. the study area is located in the campagneda plain (malenco valley, sondrio), between 2200 and 2300 metres high. 72 3. metodi la vegetazione è stata studiata secondo l’approccio sociologico della scuola di zürich-montepellier (braun-blanquet, 1964). diciannove rilievi fitosociologici, eseguiti nel periodo 2002-2003, sono stati sottoposti a cluster analysis utilizzando il programma syn-tax 2000 (podani, 2001); la classificazione gerarchica è stata ottenuta applicando il criterio agglomerativo legame medio (group average) e la similarity ratio come indice di somiglianza. l’ordinamento metrico dei rilievi è stato calcolato attraverso l’analisi delle coordinate principali (pcoa) e la distanza della corda (chord distance). le misure di diversità (numero di specie, diversità specifica di shannon & weaver, 1949: h = -σi pi ln pi), dominanza (simpson, 1949: λ = σi pi2) e di equitabilità (pielou, 1969: j = h / hmax con hmax = ln n° individui) sono state calcolate previa conversione degli indici di ricoprimento nei rispettivi valori percentuali centrali (braun-blanquet, 1964). i valori ricavati per ognuno dei quattro parametri sono stati sostituiti nell’ordinamento metrico ai numeri dei rilievi e riprodotti graficamente con simboli di grandezza proporzionale ai valori numerici ottenuti. per la nomenclatura floristica e le forme biologiche si è fatto riferimento ad aeschimann et al. (2004). per la nomenclatura fitosociologica e l’inquadramento sintassonomico ci si è attenuti a grabherr & mucina (1993) per la classe asplenietea trichomanis, a poldini & oriolo (1997) per la classe caricetea curvulae, ad eggensberger (1994) per la classe vaccinio-piceetea, a gerdol & tomaselli (1997) per la classe scheuchzeriocaricetea nigrae e ad oriolo (2001) per l’inquadramento dell’alleanza oxytropido-elynion nella classe elynoseslerietea. tuttavia il numero esiguo di rilievi e le condizioni spesso estreme cui sono soggetti i popolamenti si traducono talvolta in una loro difficoltosa attribuzione ai syntaxa noti in letteratura, di cui spesso rappresentano aspetti frammentati, floristicamente impoveriti o varianti dovute all’apporto di basi da parte delle rocce serpentinitiche. per datare i depositi glaciali che marginano le rocce montonate e per inquadrare cronologicamente il substrato su cui sono impostate, è stata ricostruita, sulla base delle geometrie assunte dagli argini morenici, la quota del limite delle nevi. tale parametro è stato calcolato con il sistema proposto da marinelli (1928) e non con il metodo aar (gross et al., 1977) per mancanza di significativi punti quotati di riferimento all’esterno delle aree glacializzate. per l’unità del cornetto è stato calcolato il limite delle nevi utilizzando anche la quota delle terminazioni, verso monte, degli argini laterali. il valore individuato è di 2680 m; ciò indica che in questa zona il metodo “marinelli”(cfr. tab. 2) sovrastima di 25 metri il reale limite delle nevi. come valore di riferimento per il calcolo della variazione dei limiti delle nevi si è tenuto conto del livello bzn (bezugsniveau) (kerschner, 1976). i valori ottenuti sono stati confrontati con quelli ricavati per le alpi svizzere (maisch, 1982). tab. 1 distribuzione altitudinale della vegetazione. altitudinal distribution of the plant communities. fasce tipi di vegetazione popolamenti discontinui di licheni e briofite nivale comunità discontinue delle rupi e delle pietraie (androsacion vandellii; androsacion alpinae) comunità delle vallette nivali (salicetea herbaceae) frammenti di praterie alpine (caricion curvulae) limite climatico delle nevi (2900 m) praterie alpine microterme ed eliofile (caricion curvulae; agrostion schraderanae; festucion variae) comunità discontinue delle rupi e delle pietraie (androsacion vandellii; androsacion alpinae) comunità delle vallette nivali (salicetea herbaceae) alpica praterie microterme pascolate (poion alpinae) cespuglietti nani a loiseleuria procumbens (loiseleurio-vaccinion) frammenti di torbiere acidofile (caricion nigrae) vegetazione fontinale (cardamino-montion) limite degli arbusti nani (2400 m) pascoli a nardo e a carex sempervirens (nardion strictae); brughiere extrasilvatiche (loiseleurio-vaccinion; rododendro-vaccinion; juniperion nanae) comunità discontinue delle rupi (androsacion vandellii) boreale superiore comunità discontinue delle pietraie e dei greti (androsacetalia alpinae; salicion incanae) (extrasilvatica) torbiere (scheuchzerio-caricetea nigrae) comunità nitrofile dei riposi (rumicion alpini) frammenti di megaforbieti (adenostylion) vegetazione fontinale (cardamino-montion) limite del bosco chiuso (2200 m) g. parolo, a. carton & a. pirola 73 4. risultati e discussione 4.1 le rocce montonate: età e contesto geomorfologico la carta geomorfologica di fig. 3 rappresenta il contesto geomorfologico in cui è inserito il gruppo di rocce montonate studiate; queste appartengono ad un ampio complesso di analoghe forme, ubicate sul versante ad occidente della linea di cresta che si sviluppa tra il passo degli ometti (2758 m) e il passo di campagneda (2601 m), passando per il pizzo scalino (3323 m) e per l’attuale esiguo ice divide che separa la vedretta di pizzo scalino dalla sua transfluenza verso nord-ovest, in direzione del piano di campagneda. il “campo” di rocce montonate (che nella sua totalità raggiunge più o meno la superficie di circa 2 km2) si sviluppa tra i 2000 ed i 2360 m di quota ed è marginato su tre lati da depositi glaciali, alcuni dei quali modellati in evidenti, ben conservati ed articolati argini morenici. al di sopra dei 2200-2250 m, le superfici rocciose montonate, affiorano per la quasi totalità. al di sotto di tale quota, pur essendo ancora evidenti i lineamenti delle rocce esarate dal ghiaccio, prendono il sopravvento morfologie di tipo più decisamente gravitativo, diffusamente ricoperte da vegetazione quasi continua. i contorni ed i profili delle rocce montonate si presentano assai spesso scabri e scheletrici, per la lunga esposizione agli agenti del modellamento che hanno agito su un substrato fissile, e sono ulteriormente marcati dall’approfondimento delle numerose fratture che le separano. l’erosione glaciale ha esaltato discontinuità del substrato diversamente orientate, scolpendo campi di rocce montonate con asse maggiore disposto lungo differenti direttrici. la frequente non coincidenza degli orientamenti della fratturazione con le probabili linee di flusso del ghiaccio (così come possono essere desunte dalla topografia e dalle rarissime tracce di esarazione lasciate sulle rocce) fanno si che spesso i dossi siano asimmetrici rispetto al loro asse maggiore, soprattutto nella parte scabra sotto corrente. i depositi glaciali posti a ridosso del campo di rocce montonate sono l’espressione di tre piccoli apparati morenici frontali di altrettanti ghiacciai di pendio, in origine saldati tra loro, che nelle ultime fasi stadiali tardiglaciali, si sono evoluti indipendentemente, in funzione delle diverse caratteristiche delle rispettive aree di alimentazione. la documentazione cartografica storica indica la presenza di ghiacciai sul versante est del piano di campagneda ancora nel 1833 (istituto geografico militare austriaco, 1833) e, con minor estensione, anche nel 1910 (carte topographique de la suisse, 1910). a fronte delle caratteristiche morfologiche, tessiturali, delle geometrie che gli argini morenici assumono e del grado di colonizzazione della vegetazione, sembra possibile effettuare una distinzione in cinque unità, strettamente locali, riferibili a diverse fasi e/o apparati glaciali. unità del cornetto (uco ). si tratta di depositi glaciali, appartenenti ad una lingua transfluente dalla vicina vedretta di pizzo scalino, modellati in un potente arco morenico, che tratteggia i limiti di una diverticolazione glaciale proveniente da una delle due insellature tra l’antecima di pizzo scalino (3107 m) ed il cornetto (2848 m). le geometrie dell’accumulo indicano che la lingua glaciale stazionava intono ai 2540 m. l’argine, nel suo lato esterno è rivestito da una prateria pingue microterma (poion alpinae) uniformemente distribuita, mentre al suo intertab. 2 tabella riassuntiva dei parametri fisici, geometrici e cronologici riferiti ai depositi glaciali, suddivisi in cinque unità. il parametro “quota limite delle nevi corretto” tiene in considerazione la differenza di quota che c’è tra il limite delle nevi calcolato con il metodo marinelli e quello più attendibile fornito, per l’unità del cornetto, dalla terminazione della morena laterale sinistra. vengono inoltre indicate le comunità vegetali presenti sulle cinque differenti unità di deposito glaciale. synoptic table showing the physical, geometrical and chronological parameters of the glacial deposits, subdivided into five units. the term “correct snow-line altitude” considers the difference of altitude between the snow-line, evaluated with marinelli’s method, and the limit obtained by measuring the upper altitude of the left lateral moraine, that is more reliable. the plant communities, that cover the five glacial units, are also indicated. unità 154 del cornetto x x 2540 2871 2705 2680 0 l.i.a. (1850 a.d.) 0,60 unità egesen di alpe prabello x x 2245 2938 2591 2566 114 bockten 10.000 ++ 1,3 unità del egesen piano di campagneda x x x 2200 2797 2499 2474 206 maximum 11.000 1,8 unità di campascio di caspoggio x x x 2060 2797 2428 2403 277 daun ii ? 13.000 + 2,3 unità di monte acquanera x 2040 2636 2338 2313 367 daun i ? 13.000 ++ 2,8 v e g e t a z io n e a n d ro sa c io n a lp in ae f e st u c e tu m s c ab ri c u lm is c ar ic e tu m c u rv u la e p o io n a lp in ae r u m ic e tu m a lp in i s ie ve rs io -n ar d e tu m s tr ic ta e r h o d o d e n d re tu m f e rr u g in e i q u o ta f ro n te ( m ) q u o ta m e d ia r e c in to ( m ) q u o ta li m it e n e vi (m ) m a ri n e lli ( 1 9 2 8 ) q u o ta li m it e n e vi c o rr e tt o ∆ h li m it e n e vi r is p e tt o a b z n 1 8 5 0 e tà m a is c h , (1 9 8 2 ) e tà b .p . m a is c h , (1 9 8 2 ) ∆ t c ° a d o g g i (g ra d ie n te 0 ,6 °c /1 0 0 m ) studio integrato fito-geomorfologico ... 74 fig. 3a) g. parolo, a. carton & a. pirola 75 fig. 3 carta geomorfologica del versante nord-occidentale tra pizzo scalino e monte acquanera. geomorphological map of the north-western slope between the scalino peak and the mount acquanera. fig. 3b) no la vegetazione, molto discontinua, è caratterizzata da consorzi discontinui microtermi tipici delle pietraie non stabilizzate (androsacion alpinae). la cartografia storica (istituto geografico militare austriaco, 1833) indica in questa posizione la presenza di una placca di ghiaccio ancora nel 1833. per questo motivo, per la freschezza delle forme, per la tipica morfologia a lama di coltello che assume la cresta dell’argine e per le caratteristiche tessiturali simili ad analoghi depositi di età nota situati nelle vicinanze, si ritiene che il deposito in oggetto possa esser riferito alla piccola età glaciale. studio integrato fito-geomorfologico ... ciali modellati in numerosi argini morenici. il deposito è coperto dal rododendreto (rhododendretum ferruginei) in modo pressoché continuo. parte del deposito si inserisce all’interno del limite superiore della vegetazione arborea; alcuni esemplari di larice si sono insediati sulla lunga morena laterale sinistra raggiungendo la quota di 2200 m. le geometrie degli argini morenici appartenenti alle unità sopra descritte suggeriscono alcune considerazioni sui limiti delle nevi, utili per datare i depositi glaciali e conseguentemente per inquadrare cronologicamente il substrato su cui si sono impostate le rocce montonate. i presunti valori della quota del limite delle nevi, assunti dai ghiacciai corrispondenti alle cinque unità individuate, sono indicati in tab 2. il valore del bzn locale è fornito dall’unità del cornetto ed è pari a 2680 m. l’unità di prabello e di campagneda si collocano nelle fasi iniziali ed intermedie dell’egesen, quelle di campascio di caspoggio e del passo degli ometti, nelle fasi tardive del daun. la differenza dell’abbassamento del limite delle nevi, tra le varie unità, in alcuni casi anche sensibile, indica che l’originale unica placca di ghiaccio si è disattivata per fasi successive da sud verso nord, abbandonando per ultimo il settore centrale in corrispondenza dell’alpe prabello. la disattivazione delle varie unità che vede nell’ordine l’unità del monte acquanera, l’unità del campascio di caspoggio, l’unità di campagneda, l’unità di alpe prabello e l’unità del cornetto, è avvalorata anche dal rispettivo grado di colonizzazione della vegetazione e dai rapporti geometrici di sovrapposizione dei relativi depositi. la superficie rocciosa che ospita le rocce montonate risulta quindi essere esposta da un’età superiore ai 13.000 anni bp; inoltre, nell’ipotesi di considerare i cambiamenti ambientali connessi solo a variazioni termiche, sulla base delle variazioni di quota del limite delle nevi, si può ritenere che nel momento in cui le rocce montonate erano attorniate dalle due lingue glaciali, le temperature medie annue si aggirassero su valori inferiori di circa 2,5 °c rispetto all’attuale, mentre quando il ghiacciaio stazionava nei pressi dell’alpe prabello potevano essere inferiori a poco più di 1 °c. 4.2 le comunità vegetali: ecologia e distribuzione in relazione alle geoforme nel campo di rocce montonate, la vegetazione si insedia preferenzialmente in corrispondenza di placche detritiche più o meno potenti, ubicate in diverse situazioni morfologiche. in particolare, le numerose fratture, orientate prevalentemente lungo due direttrici (nw÷se e wsw÷ene), individuano tra i dossi delle rocce montonate una serie di conche, di vallecole e di solchi, all’interno dei quali si raccoglie il detrito proveniente dalla degradazione delle rocce, in alcuni casi con spessori di qualche metro (fig. 4). la classificazione gerarchica dei rilievi fitosociologici (fig. 5) mostra la ripartizione dei rilievi in cinque gruppi principali, ecologicamente ben differenziati, distinti ad un valore di dissimilarità pari a 0,85: i primi tre cluster riuniscono le praterie igrofile e idro-igrofile ascrivibili alla classe scheuchzerio-caricetea nigrae, rilevate nelle depressioni, il quarto raggruppa le comunità distribuite sulle pareti rocciose (cystopteridion) e sulle coltri di alterazione (oxytropido-elynion), mentre il 76 unità del piano di campagneda (upc ). al piano di campagneda la vasta zona paludosa è sorretta da una spessa coltre di depositi glaciali, articolati in una successione di morene di accrezione e di sovrapposizione riferibili ad una lingua glaciale di ragguardevoli dimensioni (anche più di 500 m di larghezza) anch’essa diffluente dalla vedretta di pizzo scalino attraverso l’insellatura tra le quote 2911 e 2848. la maggior parte degli argini morenici mostrano profilo assai smussato ed alcuni di essi si identificano solo per una fitta serie di ondulazioni della superficie topografica, tra loro sub parallele. alcuni valli sono sostituiti da stone line. il deposito è ricoperto in modo continuo da curvuleti (caricetum curvulae), nardeti (sieversio nardetum strictae) e da localizzate praterie eliofile a festuca (festucetum scabriculmis); elevata è la pietrosità superficiale. l’unità ricopre le rocce del substrato con limiti netti e si sovrappone anche a depositi glaciali di ugual provenienza ma più antichi (unità di campascio di caspoggio). unità di campascio di caspoggio (uca ) costituisce una placca di depositi glaciali privi di espressione morfologica, che margina a nord il campo di rocce montonate. affiora nel settore settentrionale della zona e traccia i limiti della fronte di una lingua glaciale simile alla precedente ma che si spingeva più in basso nella valle. ricopre direttamente il substrato rocciose ed è a sua volta ricoperta dall’unità del piano di campagneda. il limite tra le due, di scarsa evidenza morfologica è tratteggiato da un allineamento di piccole risorgive, ristagni d’acqua, zone umide. sull’unità è presente un suolo sviluppato ed una stabilizzata copertura vegetale continua a nardo (sieversio nardetum strictae), a prateria pingue microterma (poion alpinae) e, intorno alle baite, a vegetazione dei riposi (rumicetum alpini). unità di alpe prabello (uap ) è il deposito che interferisce maggiormente con le rocce montonate, marginandole ad est, con un andamento spiccatamente sinusoidale, per una lunghezza di quasi tre chilometri. il lungo argine morenico, ben conservato, appoggia direttamente sulle nude rocce montonate. in alcuni tratti, sul lato orientale del deposito, sono presenti segmenti di morena che descrivono le fasi di ritiro di un ghiacciaio che veniva alimentato in parte dal versante tra il passo degli ometti ed il pizzo scalino ed in parte dalla vedretta di pizzo scalino, per transfluenza, lungo la già citata insellatura tra l’antecima di pizzo scalino ed il cornetto. e’ proprio in corrispondenza di questa maggior alimentazione che il deposito disegna la fronte principale più avanzata (quota di 2235 m), a ridosso dell’alpeggio di prabello e che ricopre maggiormente le rocce montonate. la vegetazione, costituita dal rododendreto (rhododendretum ferruginei) e dal nardeto (sieversionardetum strictae) ricopre questa unità in modo discontinuo a causa di una eccessiva pietrosità. il deposito glaciale in oggetto si sovrappone all’unità del piano di campagneda e del monte acquanera. unità del monte acquanera (uma ) è presente ai piedi del tratto di crinale che si sviluppa ad occidente del passo degli ometti e che culmina nel m. acquanera (2806 m). si tratta di depositi glag. parolo, a. carton & a. pirola quinto riunisce le comunità floristicamente e strutturalmente più complesse ascrivibili alle alleanze juniperion nanae, loiseleurio-vaccinion e nardion strictae, situate sui fianchi di collegamento tra i dossi e le depressioni (tab. 3). la ripartizione ecologica dei rilievi è comprovata anche dal diagramma di dispersione bidimensionale 77 fig. 4 carta geomorfologica del sistema di rocce montonate, che rappresenta con maggior dettaglio l’area di studio indicata in fig. 3. geomorphological map of the roches moutonnées system, showing in details the study area of the fig. 3. fig. 5 classificazione gerarchica dei rilievi fitosociologici. dendrogram of the phytosociological relevés. fig. 6 ordinamento metrico dei rilievi fitosociologici; gli assi i e ii esprimono rispettivamente il 22,28 % e il 15,33 % della varianza totale. metrical ordination of the phytosociological relevés; the 1st and the 2nd axes describe respectively the 22,28 % and the 15,33 % of the total variance. depressioni fianchi dossi pareti rocciose aggr ad erioph. angustifolium 2 caricetum limosae 1 caricetum pauperculae 1 drepanocl. revolv.-trichoph. cespitosi 2 1 sieversio-nardetum strictae 1 1 loiseleurio-cetrarietum 2 junipero-arctostaphyletum 2 aggr. a minuartia verna ed antenn. carpatica 3 aggr. a primula hirsuta 2 tab. 3 numero di rilievi per comunità vegetale e loro corrispondenza con le forme del rilievo. number of relevés per plant communities and their correspondence with the forms of relief. studio integrato fito-geomorfologico ... dei rilievi fitosociologici (fig. 6), che mostra cinque principali centri di raggruppamento, che nel complesso segregano bene i cinque gruppi ottenuti dalla classificazione gerarchica. le comunità individuate hanno raramente carattere transitorio, ma per lo più rappresentano aggruppamenti specializzati la cui dinamica è bloccata dalle condizioni ambientali estreme cui sono sottoposte. in fig. 7, un profilo longitudinale del sistema di rocce montonate offre la possibilità di osservare la disposizione preferenziale delle comunità vegetali rilevate, la cui distribuzione è prevalentemente correlata alla presenza di numerosi microhabitat differenziati, generati dall’eterogeneità morfologica del substrato. le conche di più grandi dimensioni (per lo più orientate nw÷se) presentano un fondo perfettamente pianeggiante con substrati saturi d’acqua. i loro fianchi assumono forme paraboloidi (i di fig. 8) se la frattura lungo la quale si sviluppa la conca è in posizione centrale rispetto alla depressione; prendono invece profili asimmetrici se la frattura è ubicata a margine della conca (ii di fig. 8). in questo secondo caso, ai piedi del fianco subverticale, si genera una falda detritica, a clasti più grossolani, decisamente più drenata rispetto alla conca. la stessa falda detritica si sviluppa anche qualora il lato a monte della conca sia limitato da una frattura ad andamento wsw÷ene, che genera una scarpata di alcuni metri di altezza. in quest’ultima situazione la conca presenta anche un maggior sviluppo equatoriale. la quasi perfetta orizzontalità del fondo è dovuta al fatto che le depressioni risultano occluse verso valle da una strozzatura prodotta da rocce montonate adiacenti o dalla presenza di un dorso roccioso in posizione centrale rispetto alla conca. la frazione fine, contenuta nei detriti presenti sul fondo, è percentualmente elevata e viene convogliata dal ruscellamento nivale e dalle piogge attive dalla primavera fino alle prime precipitazioni nevose autunnali. la frazione pelitica, inoltre, trattenendo maggiormente l’acqua, genera nelle conche porzioni di terreno a maggiore umidità che, nelle stagioni intermedie, gela fino al alcuni decimetri di profondità, rendendo superficialmente impermeabile il terreno. si genera così tra i dossi montonati un mosaico discontinuo di placche di terreno gelato, sul quale si rinvengono qua e là figure legate al gelo discontinuo. nelle depressioni si riscontrano popolamenti semisommersi paucispecifici ad eriophorum angustifolium (tab. 4) o ad eriophorum scheuchzeri in caso di ruscellamento superficiale; laddove il suolo subisce invece una legge78 fig. 7 transetto idealizzato lungo due rocce montonate in sequenza; la distribuzione dei tipi di vegetazione è correlata all’andamento del substrato, che influenza la disponibilità idrica, la durata della copertura nevosa e l’effetto del vento. 1aggruppamento rupicolo a primula hirsuta (tab. 8); 2comunità delle coltri detritiche di alterazione a minuartia verna ed antennaria carpatica (tab. 9); 3, 4, 8comunità igrofile delle depressioni: aggruppamento semi-sommerso paucispecifico ad eriophorum angustifolium (tab. 4); tricoforeto (drepanoclado revolventis-trichophoretum cespitosi, tab. 7), in condizioni edafiche più interrate con nardus stricta; caricetum pauperculae dei substrati acidi (tab. 5) e caricetum limosae (tab. 6) dei suoli poveri di nutrienti, che in estate sono soggetti a parziale emersione dalla falda acquifera; 5, 7pascoli a nardus stricta e carex sempervirens (sieversio-nardetum strictae; tab. 11); 6loiseleurio-cetrarietum (loiseleurio-vaccinion), variante pascolata a carex sempervirentis (tab. 12); 9comunità termofila a juniperus communis subsp. alpina, vaccinium gaultherioides e v. myrtillus (juniperion nanae, tab. 10); 10cenge con frammenti di brughiera extrasilvatica a rododendro (rhododendretum ferruginei), che costituisce la comunità strutturalmente più complessa del sistema di rocce montonate. idealised transect across two roches moutonnées in sequence; the distribution of the plant communities is linked to the forms of relief, that influence the water availability in the substratum, the snow cover and the wind effects. 1rupicolous community of primula hirsuta (tab. 8); 2community of minuartia verna and antennaria carpatica, typical of the alteration drift (tab. 9); 3, 4, 8wet communities of the depressions: half-submerged species-poor community of eriophorum angustifolium (tab. 4); community of trichophorum cespitosum (drepanoclado revolventis-trichophoretum cespitosi, tab. 7), with nardus stricta in dryness soils; caricetum pauperculae of the acid soils (tab. 5) and caricetum limosae (tab. 6), typical of nutrient-poor hollows, which are subject to dryness period during summer; 5, 7nardus stricta and carex sempervirens pastures (sieversio-nardetum strictae; tab. 11); 6loiseleurio-cetrarietum (loiseleurio-vaccinion), carex sempervirens grazed variant (tab. 12). 9termophilous community of juniperus communis subsp. alpina, vaccinium gaultherioides and v. myrtillus (juniperion nanae, tab. 10); 10ledges with fragment of acidocline alpenrose heaths (rhododendretum ferruginei), that is the more structured community of the roches moutonnées system. fig. 8 schema delle “trappole” di detrito ubicate tra le rocce e sulle rocce montonate. scheme showing the debris accumulation among and over the roches moutonnées. g. parolo, a. carton & a. pirola ra acidificazione si sviluppa il caricetum pauperculae (tab. 5), mentre il caricetum limosae (tab. 6) si insedia qualora i suoli siano soggetti ad un periodo estivo di abbassamento della falda acquifera. la presenza in queste comunità del nardo e delle specie ecologicamente connesse individua i settori maggiormente interrati e che subiscono un più intenso disturbo da parte del bestiame. nei casi in cui la conca non risulta occlusa verso valle o in corrispondenza di substrati più acclivi rispetto alle situazioni precedenti, si individuano vallecole sviluppate, tra le rocce montonate, per qualche centinaio di metri. i detriti che occupano queste depressioni, sempre impostate lungo fratture, sono decisamente più grossolani di quelli presenti nelle conche e di conseguenza il substrato risulta maggiormente drenato; in queste condizioni si assiste allo sviluppo di consorzi neutrofili o leggermente basifili a trichophorum cespitosum, carex lepidocarpa e carex nigra ascrivibili al drepanoclado revolventis-trichophoretum cespitosi (tab. 7). lungo le pareti subverticali delle rocce montonate, in genere orientate verso valle, si insediano comunità rupicole stabilizzate a primula hirsuta (tab. 8), ascrivibili all’alleanza cystopteridion, per la presenza di specie basifile o neutrofile dovuta all’apporto di basi da parte delle rocce serpentinitiche. lembi di detrito, atti ad ospitare placche discontinue di vegetazione, si individuano inoltre sulle superfici delle rocce montonate in corrispondenza di fratture (b di fig. 8). i detriti prevalentemente autoctoni, prodotti dalla degradazione, si assestano all’interno delle fratture e costituiscono lunghe bande che sottolineano la geometria delle discontinuità. si possono osservare 79 tab. 4 aggruppamento ad eriophorum angustifolium. community of eriophorum angustifolium. n° rilievo 12 13 specie dominante eriophorum angustifolium 3.3 3.3 classe carex echinata . + compagne callitriche palustris + . tab. 5 caricetum pauperculae (caricion nigrae). caricetum pauperculae (caricion nigrae). n° rilievo 10 diff. associazione carex paupercula 3.3 alleanza, ordine e classe carex nigra 2.2 juncus filiformis 1.2 eriophorum angustifolium 1.1 carex echinata + compagne nardus stricta 1.1 trichophorum cespitosum +.2 primula integrifolia + leontodon helveticus + potentilla erecta + agrostis rupestris + homogyne alpina + hieracium alpinum r phyteuma hemisphaericum r briofite 4.4 n° rilievo 1 2 11 diff. associazione bartsia alpina + 1.2 +.2 alleanza e ordine carex lepidocarpa 2.2 1.2 . parnassia palustris + + . selaginella selaginoides . + + carex davalliana 1.1 . . juncus alpinoarticulatus + . . classe carex nigra 4.4 1.1 2.2 eriophorum angustifolium 1.1 +.2 1.1 carex echinata + 1.2 1.1 carex paupercula . +.2 + juncus filiformis . 1.1 . compagne trichophorum cespitosum + 4.4 3.4 primula integrifolia + 3.3 2.2 leontodon helveticus + 1.1 + crepis aurea 1.1 + + potentilla erecta + 1.2 . soldanella alpina + + . nardus stricta . + +.2 salix breviserrata 1.2 . . taraxacum alpinum 1.1 . . polygonum viviparum 1.1 . . poa alpina + . . agrostis stolonifera + . . gentiana bavarica + . . deschampsia cespitosa + . . ligusticum mutellina . +.2 . agrostis rupestris . + . carex sempervirens . + . carex frigida . + . salix herbacea . + . sibbaldia procumbens . r . gentiana ramosa . r . homogyne alpina . . r briofite 1.2 1.2 3.3 tab. 6 caricetum limosae (rynchosporion albae). caricetum limosae (rynchosporion albae). n° rilievo 14 car. associazione carex limosa 5.5 alleanza, ordine e classe menyanthes trifoliata + carex nigra + eriophorum angustifolium + compagne trichophorum cespitosum + briofite + tab. 7 drepanoclado revolventis – trichophoretum cespitosi (caricion davallianae). drepanoclado revolventis – trichophoretum cespitosi (caricion davallianae). studio integrato fito-geomorfologico ... (fig. 9) mostra che la distribuzione dei rilievi risulta correlata preferenzialmente al grado di umidità del suolo (primo asse) ed alla rigidità delle condizioni ambientali (secondo asse), che è alta negli aggruppamenti rupicoli, detriticoli e acquatici, per diminuire nelle praterie pascolate, negli arbusteti nani e nelle fitocenosi igrofile più strutturate. grime (2001) sottolinea che le comunità 80 tab. 8 aggruppamento a primula hirsuta (cystopteridion). community of primula hirsuta (cystopteridion). tab. 9 ril. 15, 16, 17: aggruppamento a minuartia verna ed antennaria carpatica (oxytopydo-elynion); ril. 3: comunità di transizione verso lo junipero-arctostaphyletum, variante a f. scabriculmis (ril. 4). ril. 15, 16, 17: community of minuartia verna and antennaria carpatica (oxytopydo-elynion); ril. 3: transition community toward the junipero-arctostaphyletum, f. scabriculmis variant (ril. 4). n° rilievo 18 19 specie dominante primula hirsuta 2.2 2.2 alleanza asplenium viride 1.2 + cystopteris fragilis + + viola biflora (d) + 1.2 ordine e classe saxifraga paniculata . + compagne silene acaulis subsp. longiscapa + + minuartia verna subsp. verna + . draba aizoides subsp. aizoides + . campanula cochleariifolia + . aster alpinus + . senecio incanus subsp. carniolicus + . cardamine resedifolia + . juncus trifidus + . poa laxa . 1.1 phyteuma hemisphaericum . +.2 campanula scheuchzeri . + carex fimbriata . + astrantia minor . + huperzia selago . + briofite 1.1 2.2 n° rilievo 3 17 15 16 specie guida minuartia verna . + 1.1 1.2 antennaria carpatica (all.) . + +.2 + silene rupestris + + . + saxifraga paniculata + + + . alleanza, ordine e classe aster alpinus + 1.1 1.1 + silene acaulis subsp. longiscapa . + +.2 + agrostis alpina + . 1.1 1.2 thymus praecox subsp. polytrichus + . + . daphne striata . + . . erigeron uniflorus . . +.2 . draba aizoides . . +.2 . sedum atratum . . . + trasgr. caricetea curvulae phyteuma hemisphaericum + + . + senecio incanus subsp. carniolicus . r + + agrostis rupestris 1.1 2.2 . . pulsatilla vernalis . 1.1 + . hieracium alpinum . 1.1 + . euphrasia minima . + + . festuca scabriculmis subsp. luedii 1.1 . . . pulsatilla vernalis + . . . leontodon helveticus . + . . trifolium alpinum . r . . minuartia sedoides . . 1.1 . gentiana ramosa . . . + compagne primula hirsuta + 1.1 + + cardamine resedifolia . r r + poa alpina . . 1.1 + plantago serpentina 1.2 . . . astrantia minor + . . . juniperus communis subsp. alpina + . . . dianthus sylvestris + . . . phyteuma scheuchzeri + . . . ligusticum mutellina + . . . vaccinium gaultherioides . 2.2 . . carex sempervirens . + . . sempervivum montanum . + . . carex fimbriata . . 1.1 . campanula scheuchzeri . . +.2 . sedum alpestre . . . + briofite . 1.1 + . licheni . + . . cladonia pyxidata (l.) hoffm. . . . + cladonia merochlorophaea . asahina . . + anche placche di detrito di degradazione rimaste in loco sui dorsi delle rocce montonate nei tratti a bassa acclività (a di fig. 8). in entrambe queste situazioni si insedia una comunità a minuartia verna ed antennaria carpatica (ril. 15, 16, 17 di tab. 9); si tratta di una comunità fortemente stabilizzata dalle condizioni microclimatiche severe e dalla bassa disponibilità di elementi nutritivi. questa comunità, qualora insediata in situazioni edafiche migliori, è potenzialmente diretta verso lo junipero-arctostaphyletum (ril. 5), passando attraverso uno stadio a festuca scabriculmis (ril. 4), come testimoniato anche dal ril. 3, che rappresenta uno stadio intermedio tra le due comunità (tab. 10). lungo i fianchi ad inclinazione modesta (inferiore a 15 °c) si estendono i pascoli a nardo (sieversionardetum strictae, tab. 11), in cui è possibile individuare, in condizioni edafiche fresche, aspetti di contatto con la vegetazione delle torbiere; sulle superfici più aride e soggette ai venti, che ne asportano precocemente la copertura nevosa, si insedia una comunità microterma dominata da loiseleuria procumbens (tab. 12), sulla quale l’effetto del pascolamento favorisce la espansione di specie erbacee gravitanti nell’ambito dei caricetea curvulae e dell’alleanza nardion strictae, quali carex sempervirens, helictotrichon versicolor, leontodon helveticus e trifolium alpinum. 4.3 dinamica della vegetazione, strategie ecologiche ed organizzazione strutturale delle comunità le comunità vegetali che caratterizzano il sistema di rocce montonate rappresentano stadi dinamici la cui evoluzione e grado di complessità sono bloccati o fortemente rallentati dalla severità dei fattori ambientali. l’interpretazione ecologica del piano bidimensionale g. parolo, a. carton & a. pirola artico-alpine sono generalmente dominate da specie stress-tolleranti, nelle quali le basse temperature rappresentano la principale fonte di stress. i gruppi 2, 3 e 4 annoverano comunità adattate a vivere in condizioni ambientali molto severe ed improduttive, mentre nei gruppi 1 e 5 prevalgono fitocenosi tipiche di situazioni ambientali più permissive, dotate di una maggior disponibilità di nutrienti. la vegetazione dei dossi, qualora questi abbiano una curvatura molto accentuata, si presenta con popolamenti discontinui, dinamicamente stabili, in grado di resistere a condizioni ambientali estreme. laddove le rocce, a curvatura modesta, siano 81 n° rilievo 4 5 diff. associazione e alleanza juniperus communis subsp. alpina 2.2 4.4 sempervivum montanum (d) . +.2 ordine e classe vaccinium gaultherioides 1.2 1.1 rhododendron ferrugineum + 1.1 loiseleuria procumbens +.2 + vaccinium vitis-idaea + . variante a festuca scabriculmis festuca scabriculmis subsp. luedii 3.3 + potentilla grandiflora +.2 . bupleurum stellatum + . pedicularis tuberosa + . compagne carex sempervirens 2.2 1.1 daphne striata 1.1 + astrantia minor + + agrostis rupestris +.2 + pulsatilla vernalis r + carex fimbriata 1.2 . nardus stricta 1.1 . aster alpinus +.2 . agrostis alpina +.2 . bartsia alpina +.2 . anthoxantum alpinum +.2 . helictotrichon versicolor + . gentiana acaulis + . soldanella alpina + . primula hirsuta + . pinguicula vulgaris + . potentilla erecta + . pinus mugo subsp. mugo + . carduus defloratus + . leontodon hispidus + . parnassia palustris + . plantago serpentina + . poa alpina . 1.1 trifolium alpinum . 1.1 hieracium alpinum . + carex curvula . + veronica bellidioides . + gentiana ramosa . r solidago virgaurea subsp. minuta . + galium pumilum . + silene acaulis subsp. longiscapa . + antennaria carpatica . + silene rupestris . r carex capillaris . r campanula scheuchzeri . r n° rilievo 8 9 diff. associazione e alleanza nardus stricta 2.2 4.4 leontodon helveticus + 1.1 arnica montana + + geum montanum . + ordine e classe gentiana acaulis + + trifolium alpinum + + phyteuma hemisphaericum + + agrostis rupestris + + hieracium alpinum 1.2 . coeloglossum viride + . potentilla aurea . 2.2 helictotrichon versicolor . + compagne carex sempervirens 3.3 1.1 primula integrifolia 1.2 1.1 poa alpina + 1.2 soldanella alpina + 1.1 pulsatilla vernalis + +.2 astrantia minor + + galium pumilum + + campanula scheuchzeri r + carex fimbriata r + selaginella selaginoides r + daphne striata 2.2 . potentilla erecta 1.2 . loiseleuria procumbens + . rhododendron ferrugineum + . bartsia alpina + . rhinantus sp. + . pinguicula vulgaris + . primula hirsuta r . thesium alpinum r . crepis aurea . 3.3 festuca nigrescens . 1.1 carex lepidocarpa . 1.2 leontodon autumnalis subsp. palustris . +.2 deschampsia cespitosa . + ligusticum mutellina . + polygonum viviparum . + ranunculus montanus . + salix breviserrata . + homogyne alpina . + carex capillaris . + antennaria carpatica . + agrostis alpina . + silene acaulis subsp. longiscapa . + carex atrata subsp. atrata . + aster bellidiastrum . r licheni pycnothelia papillaria (ehrh.) l.m.doufur . 1.1 cladonia arbuscula (wallr.) flot. subsp. mitis (sandst.) ruoss . + cetraria islandica (l.) ach. . + cladonia pyxidata (l.) hoffm. . + briofite sphagnum sp. + . tab. 10 ril. 5: junipero-arctostaphyletum; ril. 4: idem, variante a festuca scabriculmis (juniperion nanae). ril. 5: junipero-arctostaphyletum; ril. 4: idem, festuca scabriculmis variant (juniperion nanae). tab. 11 ril. 8 sieversio-nardetum strictae; ril. 9 sieversionardetum strictae variante igrofila (nardion strictae). ril. 8 sieversio-nardetum strictae; ril. 9 sieversio-nardetum strictae, wet variant (nardion strictae). studio integrato fito-geomorfologico ... 82 tab. 12 loiseleurio-cetrarietum (loiseleurio-vaccinion), variante pascolata a carex sempervirentis. loiseleurio-cetrarietum (loiseleurio-vaccinion), carex sempervirens grazed variant. fig. 9 frammentazione in zolle della copertura vegetale, dovuta a processi dinamici regressivi. fragmentation of the vegetation cover, due to regressive dynamic processes. n° rilievo 6 7 car. associazione loiseleuria procumbens 3.3 4.4 alleanza asplenium viride 1.2 + cystopteris fragilis + + viola biflora (d) + 1.2 alleanza, ordine e classe juniperus communis subsp. alpina + r vaccinium gaultherioides + + hieracium alpinum + . rhododendron ferrugineum . + homogyne alpina . + trasgr. caricetea curvulae carex sempervirens 2.2 3.3 helictotrichon versicolor + 2.2 leontodon helveticus + 2.2 phyteuma hemisphaericum + + potentilla aurea + + gentiana ramosa + . pulsatilla vernalis + . trifolium alpinum . 2.2 agrostis rupestris . + nardus stricta . + compagne agrostis alpina 2.2 1.1 poa alpina 1.1 + primula hirsuta 1.2 + antennaria carpatica + + selaginella selaginoides + + salix retusa + . primula integrifolia . 1.1 carex nigra . +.2 astrantia minor . +.2 soldanella alpina . + silene rupestris . + solidago virgaurea subsp. minuta . + salix herbacea . + trichophorum cespitosum . + briofite polytrichum sp. + . tab. 13 valori di diversità (numero di specie, indice di shannon-weaver), di equitabilità (pielou) e di dominanza (simpson), calcolati per ciascun rilievo fitosociologico. diversity indexes (species richness, shannon-weaver index), evenness (pielou) and dominance (simpson), evaluated for every phytosociological relevé. cluster cl. 1 cl. 2 cl. 3 cl. 4 cl. 5 n° rilievo 1 2 11 10 12 13 14 3 17 15 16 18 19 4 5 6 7 8 9 n° specie 22 23 14 16 2 2 5 17 21 19 14 14 14 31 25 17 27 29 36 shannon 1,73 1,79 1,30 1,49 0,07 0,07 0,14 2,21 2,00 2,37 2,03 1,39 1,55 2,15 1,47 1,68 1,92 1,95 2,13 pielou 0,56 0,57 0,49 0,54 0,10 0,10 0,09 0,78 0,66 0,80 0,77 0,53 0,59 0,63 0,46 0,59 0,58 0,58 0,59 simpson 0,32 0,28 0,26 0,33 0,97 0,97 0,96 0,16 0,19 0,12 0,21 0,43 0,34 0,20 0,45 0,26 0,21 0,23 0,21 disposte consecutivamente su versanti che digradano costantemente, si può ipotizzare che tali comunità discontinue possano evolversi costituendo una cotica chiusa di collegamento tra i dossi e le depressioni. nelle depressioni, al contrario, il fattore che blocca lo sviluppo della vegetazione è rappresentato dalla costante saturazione idrica dei suoli, che li rende tipicamente anossici e microtermi. valori di ricchezza floristica (numero di specie), di diversità specifica (shannon & weaver, 1949), di dominanza (simpson, 1949) e di equitabilità (pielou, 1969) sono stati calcolati per ciascuno dei popolamenti rilevati con l’intento di dedurre informazioni sulla loro stabilità ecologica ed organizzazione strutturale (tab. 13). osservando i grafici in figg. 10, 11, 12, 13 il numero di specie è maggiore nel gruppo 5, che include le fitocenosi più strutturate ed evolute dal punto di vista dinamico. la diversità specifica, calcolata con l’indice di shannon, è alta sia in questi popolamenti sia nei popolamenti del gruppo 4, mentre assume valori via via più bassi negli altri tre gruppi. g. parolo, a. carton & a. pirola 83 tab. 14 dati stazionali dei rilievi fitosociologici. / environmental data of the phytosociological relevés. fig. 10 ricchezza specifica (numero di specie per rilevamento); 6 classi di valori dal simbolo più piccolo al più grande: ≤ 10 / 11-15 / 16-20 / 21-25 / 26-30 / ≥ 31. species richness (number of species per relevé); 6 classes of values from the smaller to the greater symbol: ≤ 10 / 11-15 / 16-20 / 21-25 / 26-30 / ≥ 31. fig. 12 equitabilità (indice di pielou); 5 classi di valori dal simbolo più piccolo al più grande: ≤ 0,40 / 0,41-0,50 / 0,51-0,60 / 0,61-0,70 / ≥ 0,71. evenness (pielou index); 5 classes of values from the smaller to the greater symbol: ≤ 0,40 / 0,41-0,50 / 0,51-0,60 / 0,61-0,70 / ≥ 0,71. fig. 13 dominanza (indice di simpson); 5 classi di valori dal simbolo più piccolo al più grande: ≤ 0,20 / 0,21-0,30 / 0,310,40 / 0,41-0,50 / ≥ 0,51. dominance (simpson index); 5 classes of values from the smaller to the greater symbol: ≤ 0,20 / 0,21-0,30 / 0,31-0,40 / 0,410,50 / ≥ 0,51. fig. 11 diversità specifica (indice di shannon-weaver); 4 classi di valori dal simbolo più piccolo al più grande: ≤ 1,00 / 1,01-1,50 / 1,51-2,00 / ≥ 2,01. species diversity of vascular plants (shannon-weaver index); 4 classes of values from the smaller to the greater symbol: ≤ 1,00 / 1,01-1,50 / 1,51-2,00 / ≥ 2,01. n° rilievo 1 2 11 10 12 13 14 3 17 15 16 18 19 4 5 6 7 8 9 altitudine 2260 2281 2285 2285 2285 2285 2275 2252 2260 2270 2245 2282 2200 2235 2260 2245 2270 2260 2265 esposizione nnw w nw n nnw sw n w se n n se n inclinazione (°) 0 4 0 0 0 0 0 25 0-15 5 2 90 80 25 5-30 10 15 15 15 superficie (m2) 12 20 1,5 2,5 2,5 2 30 5 2 6 3 1,2 2 12 5 5 25 8 15 cop. % str. arbust. 25 85 1 1 altezza (cm) 10-30 5-35 10-25 10-25 cop. % str. erb. 90 95 80 70 35 35 80 8 50 10 15 15 20 85 25 75 95 85 100 altezza (cm) 1-20 2-15 1-25 1-25 30-40 15-40 0-15 5-10 1-10 2 (5) 2 (5) 3-10 5-10 5-25 1-10 3-20 2-15 3-20 5-20 cop. % str. musc. 5 5 50 70 altezza (cm) 2 2 2* 2* n° specie vascolari 22 23 14 16 2 2 6 17 21 19 14 14 14 31 25 17 27 29 36 studio integrato fito-geomorfologico ... a questo proposito è interessante notare che i valori medio-alti di diversità assunti dai popolamenti del 4° gruppo possono mettere in dubbio l’effettiva esistenza di condizioni ambientali estreme, come invece affermerebbe la loro posizione rispetto al secondo asse dell’ordinamento metrico dei rilievi; questa apparente anomalia può essere spiegata considerando in modo integrato anche i valori di equitabilità e di dominanza. dall’analisi dei due parametri (figg. 12, 13) è possibile dedurre che il 4° gruppo, caratterizzato da una ricchezza di specie piuttosto contenuta, raggiunge alti livelli di diversità poiché le specie sono ben equiripartite all’interno dei popolamenti e, di conseguenza, non si verifica la dominanza di una o più specie sulle altre. tale comportamento è in accordo con le strategie ecologiche formulate da grime (2001), il quale afferma che la diversità è elevata in comunità dominate da specie stresstolleranti, nelle quali condizioni ambientali molto severe selezionano un numero basso di specie ecologicamente ben specializzate ed equiripartite per quanto riguarda la copertura percentuale. il gruppo 1 e, in particolare, il 5 corrispondono a popolamenti con un maggior numero di specie, ma con diversità specifica leggermente meno elevata che indica, per queste comunità sottoposte a condizioni ambientali più permissive, una maggior potenzialità di espressione dinamica. qualora la pressione ambientale dovesse manifestarsi in modo molto marcato si assisterebbe invece ad una drastica diminuzione della ricchezza e della diversità specifica e alla formazione di popolamenti paucispecifici dominati da specie ad ecologia molto specializzata; è il caso dei gruppi 2 e 3, in cui una specie, rispettivamente eriophorum angustifolium e carex limosa, assume coperture elevate grazie alla capacità incontrastata di colonizzare ambienti particolarmente selettivi, ove poche altre specie riescono a stento ad affermarsi. inoltre, le comunità vegetali possono essere soggette a regressione dinamica, in occasione di eventi climatici non ordinari, quali la prolungata sommersione della vegetazione nelle depressioni, causata da abbondanti precipitazioni, o l’inasprimento dei fenomeni erosivi sui dossi e sui fianchi rocciosi dovuti a prolungato ruscellamento superficiale. nell’area indagata, numerosi riscontri porterebbero a supporre che, in occasione di eventi piovosi eccezionali, si sia verificata l’asportazione della copertura erbacea, rimossa da processi di ruscellamento superficiale delle acque piovane, convogliate in percorsi preferenziali, lasciando isolate zolle di vegetazione sulla roccia nuda (ril. 6; comunità 6 di fig. 10; fig. 9). a questo processo, tipicamente estivo, si deve aggiungere il lento scivolamento gravitativo di grosse porzioni di suolo, ricoperto da vegetazione, lungo i pendii rocciosi caratterizzati da una discreta inclinazione, probabilmente causato da un periodico ciclo giornaliero di fusione e solidificazione di ghiaccio ipogeo, a diretto contatto con la superficie rocciosa, che si verificherebbe nella tarda primavera e nel primo autunno. 5. conclusioni l’individuazione di superfici geomorfologiche di aspetto unitario, riferibili ad una ben definita unità territoriale, rappresenta un modello di analisi paesaggistica in cui le componenti fisiche e biotiche risultano interconnesse ed inscindibili tra loro. nel sistema di rocce montonate in oggetto l’espressione floristica e strutturale delle comunità vegetali è fortemente determinata dall’andamento morfologico del substrato, poiché l’alternarsi di dossi e di depressioni condiziona la distribuzione idrica, l’esposizione al vento, l’orientamento e l’accumulo differenziato della sostanza organica e del manto nevoso. i tipi di vegetazione, almeno potenzialmente collegati da rapporti seriali sulla medesima geoforma, catenali tra dossi e depressioni, assumono una distribuzione a mosaico in cui si riscontrano, generalmente, transizioni ecotonali brusche per la rapida variazione, anche su brevi distanze, dei fattori micro-ambientali. questi ultimi influenzano la ricchezza floristica e la diversità specifica delle comunità vegetali, favorendo l’affermazione di specie a strategia stress-tollerante. il sistema di rocce montonate studiato può essere considerato un elemento fito-geomorfologico unitario del paesaggio (geosigmeto), poiché in esso è possibile riconoscere complessi di vegetazione adiacenti, che mostrano modelli distributivi caratteristici e ripetibili nello spazio. nonostante l’attività riscontrata dei processi geomorfologici e climatici, si può supporre che le comunità individuate siano potenzialmente dirette, almeno nelle situazioni edafiche migliori, verso il rhododendretum ferruginei, come osservato appena più a valle attorno ai 2100 m e sul cordone morenico dell’unità dell’alpe prabello a 2300 m. un’analisi sinfitosociologica delle comunità individuate consentirebbe infatti il riconoscimento di piccole geosigmassociazioni (hypogeosigmassociation sensu theurillat, 1992b), la cui definizione necessita di uno studio specifico esteso alla più ampia realtà territoriale di appartenenza. in conclusione si può evincere come lo studio della vegetazione e del paesaggio vegetale, in particolare in ambienti alpini, sia difficilmente svincolabile dall’analisi degli aspetti geomorfologici; il riconoscimento delle geoforme consente di estrapolare numerose informazioni di carattere fisico-strutturale, quali ad esempio l’agente morfogenetico e il rispettivo grado di attività, l’età del deposito ed informazioni pedologiche di massima (quest’ultime completate dall’analisi della litologia), che rappresentano utili strumenti di supporto nell’interpretazione della diversità vegetale di un territorio. quest’ultima si rivela un buon indicatore nella caratterizzazione di forme e processi geomorfologici, in relazione alla presenza di rapporti di dipendenza statisticamente ripetibili in condizioni ecologiche equivalenti. schema sintassonomico classe scheuchzerio-caricetea nigrae nom. mut. propos. ex steiner 1992 aggruppamento ad eriophorum angustifolium ordine scheuchzerietalia palustris nordhagen 1936 all. rhyncosporion albae koch 1926 caricetum limosae (osvald 1923) em. dierßen 1982 ordine caricetalia nigrae nom. mut. propos. ex steiner 1992 all. caricion nigrae nom. mut. propos. ex steiner 1992 eriophoretum scheuchzeri rübel 1912 84 g. parolo, a. carton & a. pirola caricetum pauperculae nom. mut. propos. ex steiner 1992 ordine caricetalia davallianae br.-bl. 1949 all. caricion davallianae klika 1934 drepanoclado revolventis-trichophoretum cespitosi nom. mut. propos. ex steiner 1992 classe caricetea curvulae br.-bl. 1948 ordine caricetalia curvulae br.-bl. in br.-bl. et jenny 1926 all. nardion strictae br.-bl. 1926 sieversio-nardetum strictae lüdi 1948 classe vaccinio-piceetea br.-bl. in br.-bl. et al. 1939 ordine loseleurio-vaccinietalia eggler 1952 all. loiseleurio-vaccinion br.-bl. in br.-bl. et jenny 1926 loiseleurio-cetrarietum br.-bl. et al. 1939 all. juniperion nanae br.-bl. et al. 1939 junipero-arctostaphyletum br.-bl. ex haffter in br.-bl. et al. 1939 all. rhododendro-vaccinion j. br.-bl. ex g. br.-bl. et j. br.-bl. 1931 rhododendretum ferruginei rübel 1911 classe asplenietea trichomanis (br.-bl. in meier et br.-bl. 1934) oberd. 1977 ordine potentilletalia caulescentis br.-bl. in br.-bl. et jenny 1926 all. cystopteridion richard 1972 aggruppamento a primula hirsuta. classe elyno-seslerietea br.-bl. 1948 ordine seslerietalia caeruleae br.-bl. in br.-bl. et jenny 1926 all. oxytropido-elynion br.-bl. 1949 aggruppamento a minuartia verna ed antennaria carpatica ringraziamenti un sentito ringraziamento alla dott. m. brusoni per la rilettura critica del testo e alla prof. m. valcuvia, alla dott.sa c. delucchi e alla dott.sa d. chiappetta per l’identificazione delle specie licheniche. bibliografia aa.vv. 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(1962) osservazioni sui cuscinetti erbosi nella valle di livigno (alpi retiche). atti istituto botanico dell’università-laboratorio crittogamico pavia, serie v, vol. xx: 1-11. pirola a., cannone n., rossi g. & zurli m. (1998) la vegetazione degli ambienti periglaciali e la sua tutela. atti del convegno internazionale: “ghiacciai e aree protette: conoscenza, conservazione, valorizzazione”, sondrio, 30 ottobre 1997. pirola a. & credaro v. (1994) osservazioni sul dinamismo della vegetazione di morena recente nel gruppo del bernina. fitosociologia, 27: 139-149. podani j. (2001) syn-tax 2000 computer program for data analysis in ecology and systematics. scienza publishing. budapest. poldini l. & oriolo g. (1997) la vegetazione dei pascoli a nardus stricta e delle praterie subalpine acidofile in friuli (ne-italia). fitosociologia, 34: 127-158. richard j.-l. 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(1971) gli stadi tardo-wurmiani e post-wurmiani nelle alpi insubriche valtellinesi. la valtellina da chiuro a delebio, la val malenco e la val masino. atti soc. it. sc. nat. e museo civ. st. nat.112 (2): 161-276. pavia. 86 ms. ricevuto il 30 novembre 2004 testo definitivo ricevuto il 2 agosto 2005 ms. received: november 30, 2004 final text received: august 2, 2005. g. parolo, a. carton & a. pirola imp.lecca& i sedimenti terrigeno-carbonatici attuali della piattaforma continentale del golfo di cagliari luciano lecca1, sandro de muro1, michele cossellu1 & mauro pau2 1dipartimento di scienze della terra, università di cagliari, via trentino 51, 09127, cagliari 2c/o faculty of physics and astronomy, princetonplein 5, postbus 80.000, 3508 ta-utrecht, the netherlands. riassunto: lecca l., de muro s., cossellu m. & pau m., i sedimenti terrigeno-carbonatici attuali della piattaforma continentale del golfo di cagliari. (it issn 0394-3356, 2005). nuove indagini ecografiche e sedimentologiche sono state intraprese nella piattaforma di cagliari con gli obiettivi di riconoscere il rapporto tra la sedimentazione terrigena e quella carbonatica, e di individuare il comportamento del sistema sedimentario durante la risalita eustatica olocenica. ad integrazione di dati già disponibili, il rilevamento ecografico, consistente di 11 nuove linee eseguite trasversalmente alla costa da riva fino al bordo della piattaforma, ha permesso di distinguere diversi ambienti sedimentari. la spiaggia sottomarina, sabbiosa e priva di vegetazione nella parte superiore e colonizzata da basse fanerogame e posidonia in quella inferiore, termina in una depressione della piattaforma interna, disposta circa parallelamente alla linea di costa. verso il largo, oltre la depressione, seguono una fascia in rilievo, sede del banco principale a posidonia e il pendio esterno al banco, a vegetazione diradata sotto la profondità di 30 metri. nel pendio esterno si osserva una fascia a onde di sabbia di altezza e lunghezza decrescenti verso il largo, fino alla profondità di circa 50 m dove prevalgono fondali planari, interrotti da bassi rilievi allungati riconducibili a paleo-linee di riva sommerse. esternamente alle paleo-rive è presente una stretta piattaforma esterna fino a circa –115÷125 m. la depressione in piattaforma interna e il rilievo di media piattaforma, sono interpretabili come antecedenze residuali della regressione “würmiana” (mis 4-2, paleo-erosione fluviale e paleo rilievo). sul paleo-rilievo si sono sovrapposti sedimenti di spiaggia sottomarina e infine il banco a posidonia debolmente aggradante e progradante, contestualmente ad un apporto terrigeno insufficiente a colmare lo spazio disponibile nella depressione prodotto dalla trasgressione post-glaciale. complessivamente sono state eseguite 98 campionature lungo le linee ecografiche e in battigia. le analisi granulometriche e composizionali semi-quantitative hanno consentito di riconoscere 8 gruppi di litofacies che documentano le caratteristiche dei diversi ambienti deposizionali. il sedimento silicoclastico attuale è confinato in piattaforma interna, dove si depongono sabbie da molto grosse a medio-fini che gradano lateralmente a sabbie molto fini e fanghi nelle depressioni. in piattaforma intermedia la produttività carbonatico-bioclastica del banco a posidonie (molluschi, briozoi, alghe rosse, echinidi e foraminiferi) dà luogo a facies bioclastiche e miste per la contemporanea presenza di sedimenti terrigeni relitti derivati dall’erosione del mare in risalita a spese di depositi di precedenti fasi eustatiche. distalmente il sedimento è in prevalenza carbonatico (alghe rosse e foraminiferi) con rari affioramenti di sedimenti misti in prossimità delle paleo-rive. la facies più distale osservata in piattaforma esterna è caratterizzata da sabbie medio-fini quarzoso-bioclastiche a lamellibranchi e foraminiferi. l’insieme delle litofacies campionate documenta che tale piattaforma ha una sedimentazione mista, terrigena e carbonatica, di mare temperato. la componente bioclastica è attribuibile all’attuale produttività in piattaforma intermedia e distale dove è prevalente, mentre la componente terrigena proviene nella spiaggia sottomarina dall’alimentazione fluvio-continentale attuale ordinata dal moto ondoso, in piattaforma intermedia e distale da sedimenti terrigeni relitti. un contesto sedimentologico analogo deve essere attribuito alle precedenti fasi di alto stazionamento eustatico del pleistocene medio-superiore. diversamente, durante le precedenti fasi glacio-eustatiche di abbassamento, stazionamento basso e risalita, la piattaforma è stata interessata da sedimentazioni terrigene emerse o di spiaggia sottomarina che vengono attualmente ri-sedimentate in piattaforma intermedia e distale. pertanto il modello deposizionale di questa piattaforma risulta costituito da fasi terrigeno-carbonatiche di mare temperato, durante la diminuzione dell’alimentazione terrigena per risalita e alto eustatico e clima mediterrano caldo poco piovoso, alternate a fasi maggiormente terrigene durante i periodi di mare basso e clima mediterraneo più fresco e più piovoso. abstract: lecca l., de muro s., cossellu m. & pau m., modern terrigenous-carbonate sediments of the continental shelf of the gulf of cagliari. (it issn 0394-3356, 2005). echographic and sedimentological investigations were undertaken on the shelf of cagliari with the purpose of underlining the relationships between modern terrigenous and bioclastic sediments and the behaviour of the sedimentary system during the holocene eustatic rising. the gulf of cagliari is a sub-tropical, semi-arid mediterranean area located in the southern part of the nw striking oligomiocene sardinian rift, within which the pliocene campidano graben is superimposed. the quaternary continental shelf developed transversally to this tectonic trough, being fed by terrigenous sediments derived from the palaeozoic metamorphic basement and from tertiary sedimentary and volcanic rocks. the new echographic survey, consisting of 11 lines performed transversally from the coast to the shelfbreak, integrated previously available data and allowed us to divide the shelf into different sedimentary environments. from shore to shelfbreak we first encounter a shoreface, gently sloped and distally seagrass-covered (close to the fair-weather wave base), which ends in a wide trough parallel to the coast. toward the open shelf is a relief, site of the posidonia oceanica main bank, reaching a minimum depth of 13 meters under the sea level, followed by its external slope. at a depth of about 30 meters the vegetation becomes rare, as less luminosity limits the growth of posidonia, and starting from depths of 35÷40 meters a large belt of sand waves appears, with gradually decreasing heigths and increasing frequencies basinward. at the depth of 50 m a flat bottom prevails, followed by several reliefs stretching roughly ne–sw at 55 m depth, interpreted as submerged shore lines. externally to such structures a narrow outer shelf occurs and the shelf break is observed at a depth of 115÷125 m. sampling sites were located along the echographic lines and on the foreshore; 98 samples were taken with a 2 dm_ grab-sampler. compositional and grain size analysis allowed us to identify 8 groups of facies related to present day depositional environments. shoreface sediments are represented by almost completely terrigenous coarse to medium sands in the eastern sector, and finer mixed terrigenous-bioclastic sands on the s. gilla shoreface. two distinct groups of lithic facies are present near capo s. elia and near p.ta zavorra, due to sediment dispersal from the limestone and andesite outcrops along the cliffed coast. the western inner-shelf depression is characterized by mixed quartzose-bioclastic sandy muds with bivalves. mixed facies of relict terrigenous sediments and present day biogenic production (mollusks, bryozoans, red algae, echinoids and foraminifers) are on the posidonia oceanica bank’s fore slope, where the siliciclastic component is found between -30 and -50 meters with decreasing importance seaward. through the sand-wave belt a transition is observed to bioclastic, poorly sorted gravely sands of red algae and foraminifers. here the sediment is completely bioclastic with rare breakthroughs of mixed sediments in proximity to the –55 m paleo-shores. from a depth of 75 meters, sediments are represented by fine bioclastic-quartzose sands with bivalves and foraminifers. a peculiar feature of this shelf is the depression in the inner shelf that can be interpreted as the product of il quaternario italian journal of quaternary sciences 18(2), 2005 201-221 202 l. lecca et al. 1. introduzione 1.1 premessa la piattaforma continentale del golfo di cagliari è stata recentemente oggetto di descrizione alla scala dell’intero bacino di cagliari (lecca et al., 1998), di studi di dettaglio in aree campione (de muro & kalb, 2003) e di valutazioni geologico-applicative finalizzate al ripascimento della spiaggia del poetto che ha suscitato accese discussioni in sedi non scientifiche. in questo lavoro, trascurando volutamente gli aspetti applicativi, si presenta la descrizione dei sedimenti, delle strutture e dei processi che costituiscono il sistema deposizionale attuale. tenuta presente l’importanza che la sedimentazione carbonatica delle zone a clima temperato (lees & buller, 1972; adey & macintyre, 1973; lees, 1975; carannante et al., 1988; pomar, 2001; pomar et al., 2004) ha avuto nei tempi neogenici e quaternari in mediterraneo (burollet, 1981; colantoni et al., 1993; fornos & ahr, 1997) e in sardegna (carboni et al, 1989; carboni & lecca, 1992; lecca et al., 1998; cherchi et al., 2000), tale tipo di sedimentazione è stata descritta e interpretata nella attuale piattaforma del golfo di cagliari. allo scopo di pervenire ad una prima sintesi alla scala dell’intera piattaforma, sono state eseguite una copertura di profili ecografici, una campionatura e le analisi sedimentologiche che hanno permesso di evidenziare, in particolare, le relazioni tra la sedimentazione terrigena dello shoreface (spiaggia sottomarina) e quella carbonatico-bioclastica della piattaforma intermedia ed esterna. 1.2 elementi geologico-regionali il golfo di cagliari è ubicato nella parte meridionale del rift sardo oligo-miocenico all’interno del quale, come è noto, si è sovrimposto il graben del campidano (pecorini, 1966; pecorini & pomesano cherchi, 1969; cherchi & montadert, 1982; casula et al, 2001; finetti et al., 2005). questo golfo si apre verso il margine continentale della sardegna meridionale dove è attivo un sistema sedimentario sottomarino composto da una piattaforma continentale, una scarpata e da diversi bacini di scarpata che contribuiscono a loro volta alla sedimentazione della piana abissale sardoalgerina (lecca et al., 1998). nella parte più interna di tale sistema sedimentario è ubicato il bacino di cagliari che rappresenta la prosecuzione del rift sardo, riattivata durante il plio-quaternario contestualmente all’apertura del tirreno. questo bacino, controllato nei tempi pliocenico-quaternari dai movimenti dei blocchi tettonici della sardegna meridionale (sulcis e sarrabus) e dai blocchi sottomarini di su banghittu e del monte ichnusa (fig. 1), è composto da una relativamente ampia piattaforma continentale, da un pendio e da una parte profonda fino a circa – 800÷1000 m (fig. 2). nella regione emersa prospiciente il golfo possono essere individuate due parti strutturalmente omogenee che proseguono nella infrastruttura della piattaforma continentale. la parte orientale comprende i promontori calcarei di cagliari e funge da horst orientale del graben del campidano, a est del quale si erge il più antico horst del rift sardo (horst del sarrabus). la parte occidentale è costituita dalla prosecuzione del graben del campidano, limitato a ovest dall’ horst del sulcis e colmato da diverse centinaia di metri di sedimenti clastici fluviali e marino-transizionali-litorali plioquaternari, derivati dalla erosione delle sequenze mioceniche del rift e delle formazioni paleozoiche. paleo-river erosions produced during the “würmian” low stand (mis 4-2), associated with terrigenous inputs insufficient to fill up the available space during the post-glacial sea level rise. towards the middle shelf the trough is bounded by paleo-reliefs where the posidonia bank at present overgrows, weakly aggrading and prograding. the depositional facies described document the present day sedimentary system as of a temperate water mixed terrigenous-carbonate shelf. the sedimentation is highly siliciclastic in the inner shelf from fluvial-continental feeding, and bioclastic in the rest of the shelf with a maximum productivity along the intermediate shelf’s posidonia bank and its foreslope. in the middle and outer shelf the siliciclastic component is related to previous eustatic phases and attributable to continental and nearshore deposits lying underneath the middle-shelf posidonia bank. analogous depositional contexts must be attributed to the preceding high stand phases of the middle-upper pleistocene. otherwise, during glacio-eustatic phases of falling, low-stand and rising sea level, the shelf has been affected by terrigenous continental sedimentation or shoreface sequences that are currently resedimented in the middle and outer shelf. in summary, the depositional model of this shelf is characterised by alternating phases of terrigenous-carbonate sedimentation of middle latitude, with a poorly rainy, warm mediterranean climate during highstanding sea-level conditions, and terrigenous phases during low stands with rather rainy, cooler mediterranean climate. parole chiave: piattaforma continentale, sedimenti terrigeno-carbonatici, sedimenti relitti, posidonia oceanica, variazioni eustatiche, quaternario, sardegna. keywords: continental shelf, terrigenous-carbonate sediments, relict sediments, posidonia oceanica, sea level change, quaternary, sardinia. fig.1 schema geologico della sardegna meridionale e ubicazione dell’area studiata. geological sketch of southern sardinia and location of the studied area. 1.3 la piattaforma del golfo di cagliari la piattaforma continentale del golfo di cagliari, ubicata trasversalmente al rift sardo oligo-miocenico della sardegna meridionale, dal punto di vista strutturale e sedimentologico risulta costituita dalla congiunzione di tre diversi segmenti: la terminazione orientale della piattaforma del sulcis, la piattaforma di cagliari s.s., che costituisce la parte più importante, e la stretta piattaforma del sarrabus (fig. 2). i tre segmenti di piattaforma vengono alimentati da apporti terrigeni, di cui non sono disponibili valutazioni quantitative, provenienti da tre diverse aree. il sarrabus, costituito in prevalenza da metamorfiti erciniche di basso grado, da plutoniti tardo erciniche e, nella regione costiera, da sequenze clastiche continentali e marine mioceniche e quaternarie. il sulcis, dove affiorano in genere rocce del basamento ercinico, localmente coperture sedimentarie paleogeniche terrigene e, in prossimità della faglia occidentale del graben del campidano, importanti apparati vulcanici andesitici oligo-miocenici. infine l’area di cagliari, la cui parte orientale è costituita da marne e marne arenacee del miocene inferiore e medio e da arenarie e calcari di piattaforma bioclastico-algale del miocene superiore, e quella occidentale costituita dai complessi continentali e transizionali-litorali pliocenicoolocenici del campidano meridionale. le prime descrizioni di questa piattaforma risalgono a segre (1968), che al di sotto dei sedimenti attuali riconobbe elementi morfologici riconducibili alla risalita eustatica del pleistocene superiore-olocene, e alle indagini eseguite mediante la nave oceanografica bannock (c.n.r.) dall’università di genova che consentirono le prime descrizioni sedimentologiche (piccazzo et al., 1981). sulla base di nuovi rilievi ecografici e sismici, realizzati nell’ambito del progetto oceanografia 203i sedimenti terrigeno carbonatici ... e fondi marini-cnr (carta et al., 1986), e di successive ricerche, seguirono descrizioni di dettaglio dei paleodepositi litorali interpretati come beach rock (ulzega et al. 1986; de muro & orrù, 1998). l’architettura complessiva della piattaforma di cagliari, ricostruita principalmente sulla base di linee sub-bottom profiler e sparker 500 j, risulta costituita da tre accrescimenti debolmente progradanti: uno silicoclastico di shoreface, uno bioclastico della media piattaforma e infine uno fangoso della piattaforma esterna-pendio, all’interno di un bacino estensionale (lecca et al.,1998). tali progradazioni sono state attribuite ad ambienti deposizionali distinti, attivi contemporaneamente e relativi allo stazionamento alto (high stand) tardo olocenicoattuale, che mostrano alimentazioni sedimentarie, facies e fattori di controllo diversi. la sezione più completa di tale piattaforma mostra una sequenza di ambienti, disposti circa parallelamente alla costa e rappresentativi di piattaforme terrigeno-carbonatiche di mare temperato. il clima a cui è soggetto il golfo di cagliari, come noto, è mediterraneo caldo (sub-tropicale), poco piovoso (inferiore a 500 mm/a; pinna 1971; raimondi et al, 1995). il regime delle maree è microtidalico con massimi di circa 40 cm, la salinità è di circa 37÷38‰, le temperature medie superficiali del mare oscillano tra i 13° invernali e i 24° estivi (metallo, 1971; mosetti, 1977). 2. dati un nuovo rilevamento ecografico, eseguito tra il 2002 e il 2003, ha permesso la precisazione di elementi batimetrici e l’ubicazione di una nuova campionatura dei sedimenti (cossellu, 2003; pau, 2003). sono stati eseguiti 9 profili narrow-beam (200 khz), perpendicolarmente alla linea di costa fino alla profondità di circa 125 metri e spaziati da 2 a 4 km, e due profili multi-beam side scan sonar (reson seabat 81125) di comparazione (fig. 3). tali dati sono stati integrati con le linee sparker (500 j) ed ecografiche già disponibili e utilizzate in lecca et al. (1998). complessivamente sono state eseguite 77 campionature, di cui 33 lungo la battigia e 44 in piattaforma fino alla profondità di circa 50 m mediante benna van veen del volume di 2 dm3. queste ultime sono state effettuate lungo le linee ecografiche per fasce batimetriche: un campione alla profondità di 5 metri, tre campioni tra la fine del primo banco a posidonie e l’inizio del banco principale (dove questa suddivisione è presente), un campione all’interno del banco principale, un campione dopo il limite inferiore della prateria a circa –35 m ed un campione attorno ai –50 m. a causa della presenza continua della prateria a posidonie, non tutte le campionature hanno recuperato sedimento; al fine di evidenziare tale dato le campionature senza prelievo sono state indicate in chiaro nella carta di posizionamento (fig. 3). inoltre, sono stati analizzati 23 campioni prelevati nella parte distale della piattaforma (–50 ÷ –103 m), non inseriti nella tabella 1, che costituiscono parte di uno studio ancora in corso e attinente il dottorato di ricerca di uno degli autori (m. cossellu). la maggior parte delle operazioni sono state svolte a bordo di un’imbarcazione messa a disposizione fig.2 sistema deposizionale del golfo di cagliari: 1) depressioni della piattaforma interna; 2) prateria a posidonia; 3) fascia a sand waves; 4) paleo-linee di riva. depositional system of the gulf of cagliari: 1) troughs of the inner shelf; 2) posidonia meadows; 3) sand wave belt; 4) paleoshorelines. 204 dalla base logistico-operativa navale del corpo forestale e di vigilanza ambientale della regione sardegna. l'utilizzo di un'imbarcazione con ridotto pescaggio (0,5 m) ha consentito di eseguire i profili e le campionature a poca distanza dalla linea di costa, in fondali bassi fino a 1 metro circa. 3. zonazione delle facies ecografiche nelle registrazioni ecografiche sono state riconosciute la tipologia del fondo marino e alcune caratteristiche sedimentarie grazie alla struttura della riflessione e ai caratteri del segnale (figg. 4 e 5). la risposta ecografica risulta più o meno lunga a seconda che il segnale sia stato riflesso o diffratto da diversi tipi di fondale marino. in genere una risposta breve si associa a superfici deposizionali lateralmente continue prodotte da sedimenti sabbiosi con coda fine e regolare coefficiente di riflessione, mentre una risposta più lunga evidenzia superfici irregolari o materiali di maggior granulometria. le posidonie sono facilmente riconoscibili dai caratteristici gradini che evidenziano la presenza di mattes (sensu perez & picard, 1964), e canali o depressioni chiuse di inter e intra-matte. la prateria fitta e continua si riconosce per una morfologia ondulata non periodica e una maggior lunghezza della risposta ecografia rispetto alle aree in sedimentazione sabbiosa con fondali planari e ondulati. un tipico pattern ecografico indicativo della presenza di sand waves, conosciuto in altre piattaforme (allen, 1982; mccave & longhorne, 1982; fornos & ahr, 1997), è costituito da un’alternanza di risposta breve nella cresta e di una risposta lunga nel cavo delle ondulazioni (fig. 4f). fig.3 ubicazione delle nuove linee ecografiche, delle campionature e delle figure 4, 5, 7, 9 e 10. location of new echographic lines, sampling sites and figures 4, 5, 7, 9 and 10. l. lecca et al. 205 fig. 4 principali tipologie dei profili ecografici: a) shoreface sabbioso e inizio prateria interna; b) depressione della piattaforma interna; c) transizione al banco principale a posidonia; d) prateria a terrazzi; e) prateria diradata e transizione alla fascia a sand waves; f) sand waves; g) paleo linea di riva; h) bordo della piattaforma; i) depressione e banco principale a posidonia in profilo side-scan sonar. ubicazione in fig. 3. main ecographic patterns: a) sandy shoreface and beginning of inner posidonia meadows; b) inner shelf trough; c) transition to midshelf posidonia bank; d) terraced meadows; i) bank slope and transition to sand wave belt; f) sand waves; g) drowned shoreline; h) shelfbreak; i) trough and posidonia bank in side-scan sonar profile. for locations see fig.3. i sedimenti terrigeno carbonatici ... 206 dalle linee ecografiche può inoltre essere dedotta la posizione dei livelli idrodinamici critici relativi al moto ondoso, consentendo di riferire l’inizio delle prateria continua circa alla “base del moto ondoso di bel tempo” (fair weather wave base: fwwb) nella parte interna della piattaforma, e la transizione dalla fascia a sand waves ai fondali planari alla “base del moto ondoso di tempesta” (storm wave base: swb) in piattaforma intermedia. l’assenza in tutte le linee ecografiche di avvallamenti o incisioni localizzate e il prevalere di limiti zonali tendenzialmente paralleli alle isobate inducono a ritenere che l’idrodinamismo sia attribuibile in prevalenza al moto ondoso, rispetto a correnti di fondo di piattaforma. sulla base dell’intera copertura ecografica disponibile sono stati riconosciuti i caratteri morfologicodeposizionali dei principali ambienti della piattaforma (fig. 6). 3.1 piattaforma interna shoreface lo shoreface superiore è caratterizzato da una superficie inclinata debolmente convessa, spoglia di vegetazione sottomarina, che si estende in prosecuzione delle spiagge fino alla profondità di circa 3÷8 m (fig. 4-a). lo shoreface inferiore è invece variamente colonizzato da posidonie e da altre fanerogame. tale unità è assente davanti alle falesie di p. zavorra e di c. s. elia e ai promontori della piattaforma del sarrabus. prateria interna da pochi metri di profondità si sviluppano cespugli isolati di posidonie seguiti da mattes generalmente basse, piccole depressioni chiuse e canali profondi 1÷2 m riempiti di sedimento. più esternamente, al di sotto di una profondità critica di attenuazione dell’azione erosiva del moto ondoso, variabile nelle diverse aree del golfo, la prateria interna è invece più continua (fig. 5). nelle parti più profonde della depressione, davanti allo shoreface di s. gilla, il fondale passa gradualmente a superfici spoglie. depressioni della piattaforma interna due peculiari depressioni, disposte circa parallelamente alla linea di costa, sono presenti nella parte più interna della piattaforma a ne e a sw del capo s. elia, profonde rispettivamente 22 e 27 m (profilo t4, fig.5-a e profilo t7, fig. 5-b). tali depressioni risultano protette dalle tempeste dei quadranti meridionali grazie alla presenza del banco a posidonie della media piattaforma. il fondo della depressione del settore occidentale è spoglio e perfettamente planare, e viene pertanto associato a una sedimentazione fangosa; diversamente in quella orientale anche il fondo è colonizzato da fanerogame. 3.2 piattaforma intermedia banco principale a posidonie la culminazione della piattaforma intermedia è sede del banco principale a posidonie, che verso il largo prosegue con un debole pendio esterno. verso terra il banco è limitato da un netto pendio di transizione alle depressioni (figg. 4c e 5). all’interno del banco possono essere individuate diverse tipologie della fi g .5 s e zi o n i e c o g ra fic h e in te rp re ta te d e i p ro fil i t 4 ( a ) (s p ia g g ia d e l p o e tt o ) e t 6 ( b ) (s p ia g g ia d e lla p la ya ). f w w b : b a se d e l m o to o n d o so d i b e l t e m p o ; s w b : b a se d e l m o to o n d o so d i t e m p e st a . s c a la o ri zz o n ta le d e l p ro fil o b d o p p ia r is p e tt o a q u e llo a . u b ic a zi o n e in f ig . 3 . in te rp re te d e c h o g ra p h ic s e c ti o n s o f th e p ro fil e s t 4 ( a ) (a fo re p o e tt o b e ac h ) an d t 6 ( b ) (a fo re p la ya b e ac h ). f w w b : fa ir w e at h e r w av e b as e ; sw b : st o rm w av e b as e . h o ri zo n ta l s c al e o f th e p ro file b d o u b le d in c o m p ar is o n t o t h at o f a . f o r lo c at io n s se e f ig .3 . l. lecca et al. distribuzione areale delle posidonie. la prateria a mattes alte 3÷4 m, con relativi canali e depressioni, occupa la parte alta e prossimale del banco, da circa –10÷15 m fino a circa –25 m presentando, probabilmente in relazione con l’idrodinamismo del moto ondoso, una tipica geometria terrazzata con ampi ripiani e gradini rivolti verso il largo (fig. 4d). analogamente alla prateria interna delle depressioni, la struttura appare distalmente più continua e omogenea, evidentemente per diminuzione dell’energia idrodinamica. la prateria prevalentemente continua occupa un’areale compreso tra i –20÷25, fino circa –30 m che costituisce il limite inferiore attribuibile al fattore luminosità (fig. 4e). sand waves lungo il pendio esterno la prateria passa a un fondale a morfologia ondulata interpretata come onde di sabbia (fig. 4f). le strutture, che hanno inizialmente una lunghezza d’onda di circa 200 m e un’altezza di 3 m circa, aumentano in frequenza e assumono dimensioni minori procedendo verso il largo. le waves sono asimmetriche con i lee sides rivolti verso terra indicando una direzione del trasporto associabile principalmente alla base delle onde di tempesta provenienti da se (istituto idrografico della marina, 1980). il limite inferiore si individua a una profondità di 50÷55 metri e viene messo in relazione con la profondità massima di azione delle onde di tempesta. fondali piani esternamente alla fascia a sand waves si instaurano fondali a morfologia piana che indicano una ulteriore diminuzione dell’idrodinamismo. tale fascia è limitata verso l’esterno dall’affioramento di diverse paleo-forme litorali, tra i –50 e i –60 m circa, relative a livelli di basso eustatico del pleistocene superiore. la maggiore di queste strutture (fig. 4h) si presenta allungata sw-ne e in rilievo di circa 4-5 m, e nella parte nord-orientale mostra talvolta due culminazioni con andamento subparallelo ricoperte da pinnacoli algali sub attuali. 207 fig.6 zonazione degli ambienti deposizionali sulla base dell’analisi dei profili ecografici. sedimentary framework of the gulf of cagliari, based on the analysis of the echographic profiles: 1) shoreface; 2) discontinuous inner posidonia meadows; 3) continuous inner posidonia meadows; 4) inner shelf trough; 5) mid-shelf posidonia bank; 6) fore slope depleted posidonia; 7) sand wave belt; 8) plane bottoms; 9) drowned shorelines; 10) bioherms on paleo-shores; 11) shelfbreak. i sedimenti terrigeno carbonatici ... 3.3 piattaforma esterna: all’esterno delle paleo-forme, il fondo marino mostra inizialmente un ridotto versante ricoperto da un accrescimento sigmoide fangoso olocenico (–60÷80 m circa), seguito da una fascia a debole pendenza che termina con un bordo a circa –125 a sedimentazione progradante inclinata (fig. 4h). la rottura di pendio della stretta piattaforma esterna nella parte nord-orientale avviene a circa –90 m per attività erosionale retrograda del canyon s. elia-foxi, mentre nella piattaforma del sarrabus (fig. 3 transetto t1) è individuabile a –70 m per controllo strutturale. 4. analisi dei sedimenti 4.1 granulometrie seguendo le consuete metodologie dell’analisi granulometrica, i campioni sono stati suddivisi in 7 classi con intervalli interi di unità φ tra 4000 e 63µm. per ogni campione è stata realizzata la curva di frequenza, utilizzata nella valutazione percentuale delle varie tipologie di granuli, e la curva cumulativa mediante la quale è stato calcolato il coefficiente di cernita (σφ = (φ 84 φ16 )/2, inman, 1952; tab. 1). 4.2 composizione per motivi di celerità è stato adottato un metodo semi-quantitativo, eseguendo il riconoscimento delle diverse componenti al microscopio binoculare e valutando contestualmente le percentuali areali mediante comparatori per stima visiva (bacelle & bosellini, 1965; swanson, 1985). data la varietà delle componenti e la taratura dei comparatori ogni 5÷10 %, i risultati ottenuti sono soggetti a errori dell’ordine del ±10% della singola componente. le varie famiglie di granuli sono state distinte sulla base dei caratteri morfologici, del colore e del comportamento all’attacco hcl diluito. allo scopo di valutare l’importanza delle diverse componenti, le stime areali sono state moltiplicate per il peso di ciascuna frazione e infine normalizzati sul campione totale. pertanto il significato del valore percentuale così ottenuto non è più strettamente ponderale, bensì ponderale-areale. il metodo inoltre, non tenendo conto delle differenze di peso di volume, per esempio tra bioclasti e clasti terrigeni, contiene ulteriori errori nelle valutazioni ponderaliareali. poiché i vari bioclasti hanno diverse porosità intragranulare e conseguentemente diverso peso di volume, tali errori non possono essere corretti tramite l’introduzione di un unico coefficiente. al fine di valutare l’ordine dell’errore, su cinque campioni sono state eseguite le calcimetrie (misura della co2 sviluppata su attacco con hcl) che hanno evidenziato una sopravvalutazione complessiva del carbonato bioclastico e delle frazioni fangose nelle stime ponderali-areali rispetto a quelle rigorosamente ponderali, intorno al 10%÷15%. questi errori, superabili nel prosieguo della ricerca con più precise metodologie, non pregiudicano tuttavia il significato deposizionale dei risultati, consentendo la suddivisione dei sedimenti campionati in tre principali gruppi di facies: silicoclastiche, miste e bioclastiche. componente terrigena sono state distinte le seguenti componenti terrigene: quarzo, feldspati s.l., miche s.l., litoclasti metamorfici e magmatici, litoclasti calcarei, minerali accessori e granuli antropici. in generale il criterio di riconoscimento per il quarzo è basato sul suo aspetto vitreo; il feldspato s.l., spesso riconoscibile sulla base della forma, raramente idiomorfa, della presenza di sfaldature e del colore; il k-feldspato è distinguibile per il tipico colore più o meno roseo e i plagioclasi per il colore biancastro. tali criteri qualitativi in certi casi possono aver portato alla confusione di specie mineralogiche, ma è certamente affidabile per la distinzione dei feldspati s.l. rispetto al quarzo e per il riconoscimento del litico in base all’evidenza della morfostruttura, del colore e della polimineralogia. in ogni caso queste imprecisioni nel riconoscimento dei granuli non influiscono sulla finalità dello studio, che è maggiormente rivolto alla valutazione dei rapporti tra la totale componente terrigena e quella carbonatico-bioclastica. componente bioclastica la componente bioclastica, facilmente distinguibile in base alla struttura scheletrica confrontata con la fauna descritta nel mediterraneo e nella piattaforma sarda (d’angelo & gargiullo, 1978; riedl, 1991; boudoresque et al., 1992 cum. bibl.), risulta costituita dai seguenti organismi: molluschi (bivalvi e gasteropodi in frammenti e gusci interi), talli di alghe rosse, colonie di briozoi, foraminiferi (soprattutto forme bentoniche), echinodermi (frammenti di gusci e radioli), ostracodi (presenti nelle frazioni 500÷125 µm) e numerosi organismi a guscio chitinoso-proteico appartenenti principalmente agli artropodi. inoltre si segnala la presenza di fecal pellets in alcuni campioni della depressione interna occidentale. in questa piattaforma, come in tutto il mediterraneo, gran parte della produzione bioclastica deve essere associata all’ecosistema della posidonia (posidonia oceanica, l., delile) che assieme a cymodocea nodosa (ucria, ascherson), zostera noltii (hornemann) e zostera marina (l.), esercita un controllo ecologico dominante e ha importanti relazioni di feedback con l’intero sistema biologico e sedimentario (unesco, 1977). nell’ambito dell’intera piattaforma, che per l’importanza della componente organogena è da considerarsi come carbonatica cold temperate-transitional (zona b zona c sensu carannante et al., 1988), emerge che i produttori più significativi sono le alghe rosse. tra queste possono essere distinte le alghe calcificate, dirette produttrici di bioclasti, dalle specie non calcificate dove la deposizione di carbonato si verifica solo nella parte sciafila per opera di organismi epifiti. il gruppo più produttivo è quello delle corallinacee, come noto proviste di tallo (hypothallium e perithallium) calcificato (adey & macintyre, 1973; riedl, 1991). la distinzione speditiva tra i generi e le specie è stata eseguita mediante il confronto con le forme descritte in letteratura (johnson, 1962; johnson & adey, 1965; boudoresque et al., 1992) che possono essere variamente ramificate (lithophyllum racemus, lithothamnium fruticulosum), incrostanti o a struttura a foglia (per esempio lithophyllum expansum, pseudolithophyllum expansum e mesophyllum lichenoides). tra le varie forme sembrano prevalere quelle a ramificazioni distanziate (loose branching, cfr. lithothamnium solutum, johnson, 1962) non fissate sul fondo rispetto alle forme incrostanti e a 208 l. lecca et al. 209 tab. 1 granulometrie, cernita e composizione dei campioni analizzati. nei totali con asterisco non è compresa la componente organica. arrotondamenti all’unita percentuale. grain sizes, sorting and compositions of the analized samples. values with asterisk lack the organic component. approximation to the whole number. campione prof. classi % peso unita φ σφ componente terrigena comp. (m) < -1 -1 ÷ 0 0 ÷ 1 1 ÷ 2 2 ÷ 3 3 ÷ 4 > 4 quarzo feldsp. minori litoc. totale bioc. rc1 50% 31% 9% 9% 0% 0% 0% 0,80 53% 43% 0% 4% 100% 0% rc2 25% 66% 9% 0% 0% 0% 0% 0,55 49% 47% 0% 3% 100% 0% rc3 38% 50% 11% 0% 0% 0% 0% 0,60 53% 40% 0% 7% 100% 0% rc4 38% 44% 6% 4% 7% 0% 0% 0,70 46% 44% 0% 5% 96% 4% rc5 0% 3% 22% 60% 14% 0% 0% 0,65 53% 33% 2% 4% 92% 8% rc6 0% 0% 6% 59% 34% 0% 0% 0,60 56% 32% 3% 3% 91% 9% rc7 0% 0% 0% 2% 85% 12% 0% 0,35 64% 21% 6% 1% 93% 7% rc8 23% 49% 5% 7% 15% 1% 0% 1,55 48% 42% 1% 6% 98% 2% rc9 5% 40% 30% 18% 7% 0% 0% 1,05 53% 39% 0% 7% 99% 1% rc10 2% 31% 42% 21% 4% 0% 0% 0,90 51% 39% 0% 10% 100% 0% rc11 17% 60% 16% 5% 1% 0% 0% 0,60 46% 42% 0% 12% 100% 0% rc12 19% 68% 6% 3% 5% 1% 0% 0,50 50% 39% 0% 10% 100% 0% rc13 3% 58% 35% 3% 1% 0% 0% 0,70 50% 42% 0% 8% 100% 0% rc14 26% 30% 9% 7% 23% 4% 0% 1,85 39% 31% 1% 25% 96% 4% rc15 23% 28% 10% 8% 26% 4% 0% 1,85 40% 34% 1% 22% 97% 3% rc16 3% 13% 55% 27% 1% 0% 0% 0,65 50% 39% 0% 11% 100% 0% rc17 1% 3% 3% 24% 68% 1% 0% 0,55 57% 33% 2% 3% 95% 5% rc18 0% 1% 36% 61% 2% 0% 0% 0,60 55% 36% 0% 9% 100% 0% rc19 0% 3% 8% 25% 61% 2% 0% 0,70 62% 30% 1% 5% 99% 1% rc20 1% 5% 3% 8% 82% 2% 0% 0,40 62% 32% 3% 3% 100% 0% rc21 3% 4% 7% 64% 22% 0% 0% 0,60 50% 28% 0% 20% 98% 2% rc22 0% 0% 0% 21% 77% 2% 0% 0,45 53% 35% 1% 4% 93% 7% rc23 0% 0% 4% 18% 61% 17% 0% 0,60 59% 28% 3% 4% 92% 8% rc24 0% 1% 3% 30% 56% 8% 0% 0,65 64% 30% 2% 3% 98% 2% rc25 0% 0% 5% 56% 39% 0% 0% 0,60 61% 29% 0% 7% 98% 2% rc26 1% 2% 6% 18% 72% 1% 0% 0,55 53% 16% 2% 2% 73% 27% rc27 1% 5% 67% 22% 6% 0% 0% 0,60 13% 7% 0% 3% 29% 77% rc28 5% 8% 33% 27% 25% 2% 0% 1,15 19% 7% 0% 2% 29% 71% rc29 6% 20% 60% 10% 3% 0% 0% 0,65 12% 5% 1% 80% 99% 1% rc30 0% 4% 35% 33% 27% 1% 0% 1,00 44% 33% 1% 9% 87% 13% rc31 1% 0% 0% 2% 81% 15% 0% 0,40 50% 28% 5% 2% 85% 15% rc32 15% 34% 35% 9% 6% 0% 0% 1,00 39% 49% 1% 3% 92% 8% rc33 43% 37% 20% 0% 0% 0% 0% 0,75 1% 0% 0% 85% 86% 14% t1c1 7,0 0% 0% 1% 28% 65% 4% 0% 0,60 55% 38% 4% 2% 100% 0% t1c2 10,0 0% 3% 56% 40% 0% 0% 0% 0,60 56% 39% 1% 4% 100% 0% t1c3 40,0 8% 42% 33% 13% 3% 1% 0% 0,90 1% 1% 0% 0% 3% 97% t2c1 3,5 0% 0% 1% 6% 57% 33% 3% 0,65 64% 28% 3% 3% 98% 2% t2c2 5,5 1% 1% 1% 6% 58% 26% 7% 0,60 67% 21% 4% 2% 94% 6% t2c5 39,2 13% 42% 34% 9% 1% 0% 0% 0,85 1% 1% 0% 0% 3% 97% t2c6 50,5 14% 33% 34% 13% 5% 1% 0% 1,05 1% 1% 0% 0% 2% 98% t3c1 1,0 0% 0% 4% 48% 41% 7% 0% 0,70 70% 27% 1% 2% 99% 1% t3c2 14,2 35% 56% 8% 0% 0% 0% 0% 0,55 44% 19% 0% 36% 99% 1% t3c3 21,8 25% 31% 20% 12% 8% 4% 1% 1,40 2% 1% 0% 1% 4% 96% t3c4 33,0 3% 9% 18% 30% 22% 15% 3% 1,40 18% 9% 1% 3% 31% 69% t3c5 52,4 13% 20% 20% 20% 19% 8% 1% 1,70 0% 0% 0% 0% 0% 100% t4c1 6,0 0% 0% 0% 1% 40% 56% 3% 0,65 67% 27% 2% 1% 97% 3% t4c5 35,0 9% 33% 35% 16% 5% 2% 0% 1,05 15% 11% 0% 4% 30% 70% t4c6 51,0 5% 16% 43% 28% 7% 2% 0% 0,95 18% 7% 0% 2% 27% 73% t5c1 1,6 0% 0% 1% 31% 50% 15% 3% 0,70 36% 0% 51% 0% 87% 13% t5c2 4,3 0% 0% 3% 88% 8% 0% 0% 0,35 45% 5% 43% 0% 93% 7% t5c4 33,5 4% 13% 23% 31% 24% 5% 0% 1,30 32% 8% 0% 3% 43% 57% t5c5 48,3 19% 46% 25% 8% 2% 1% 0% 0,90 0% 0% 0% 0% 0% 100% t6c1 2 0% 0% 0% 0% 69% 29% 1% 0,50 51% 13% 2% 3% 69% 31% t6c2 4 0% 0% 0% 1% 17% 55% 27% 0,70 39% 29% 1% 3% 72% 28% t6c3 8 30% 16% 16% 16% 13% 7% 1% 1,85 12% 3% 0% 0% 15% * 79% t6c5 12,5 25% 20% 15% 0% 31% 7% 2% 2,00 17% 5% 0% 2% 26% 74% t6c6 23,2 0% 0% 0% 0% 0% 0% 100% 0,30 20% 10% 0% 5% 35% * 30% t6c7 29 3% 18% 19% 23% 25% 9% 2% 1,50 18% 13% 0% 11% 43% 57% t6c8 50,1 14% 48% 27% 7% 3% 2% 0% 0,90 3% 0% 0% 0% 3% 97% t7c1 2,1 0% 0% 0% 0% 35% 60% 4% 0,65 62% 6% 6% 3% 77% 23% t7c2 5,3 0% 0% 0% 0% 3% 69% 27% 0,55 61% 7% 3% 3% 75% * 9% t7c3 11,9 68% 10% 6% 5% 4% 5% 2% 1,20 4% 2% 0% 1% 7% * 86% t7c4 17 12% 7% 11% 46% 20% 4% 1% 1,35 30% 11% 0% 4% 45% * 31% t7c5 24,4 0% 0% 0% 19% 61% 16% 4% 0,60 34% 10% 2% 21% 67% * 29% t7c7 36,6 22% 43% 20% 9% 4% 2% 1% 1,00 30% 9% 0% 17% 56% 44% t7c8 50,7 10% 32% 29% 17% 9% 3% 0% 1,25 0% 0% 0% 0% 0% 100% t8c1 1 2% 4% 8% 25% 50% 10% 1% 0,85 34% 21% 0% 0% 66% 44% t8c2 10,5 1% 4% 6% 10% 9% 22% 48% 1,55 48% 23% 2% 3% 76% 24% t8c3 15 0% 0% 0% 0% 9% 30% 60% 0,70 41% 20% 5% 6% 71% 29% t8c4 23 0% 0% 0% 0% 0% 0% 100% 0,30 20% 10% 0% 5% 35% * 30% t8c5 25 5% 10% 22% 31% 27% 4% 0% 1,25 32% 19% 0% 4% 55% * 37% t8c6 32 7% 31% 27% 16% 15% 4% 1% 1,45 26% 22% 0% 18% 66% 33% t8c7 50 12% 40% 28% 11% 6% 3% 1% 1,10 2% 0% 0% 0% 2% 98% t9c1 1,9 20% 29% 34% 15% 1% 0% 0% 1,05 3% 6% 0% 28% 38% 62% t9c2 6,5 32% 46% 15% 8% 0% 0% 0% 0,80 4% 6% 0% 43% 53% 47% t9c5 37 7% 38% 43% 7% 3% 2% 1% 0,85 38% 17% 0% 13% 68% 32% t9c6 51 5% 36% 38% 14% 5% 1% 0% 0,95 2% 1% 0% 0% 3% 97% c a m p io n i in b a t t ig ia c a m p io n i in p ia t t a f o r m a i sedimenti terrigeno carbonatici ... quelle globose. tra le specie debolmente calcificate si osserva peyssonnelia squamaria (gruppo delle peyssonneliaceae, cui fanno parte organismi a diversi gradi di calcificazione), che presenta una consistenza fogliacea. tra le forme non calcificate infine troviamo frequentemente la specie vidalia volubilis, in quantità volumetricamente rilevante nei sedimenti mobili della piattaforma intermedia, oltre il limite della posidonia. generalmente nelle frazioni granulometriche superiori a 0,5 mm si rinvengono frammenti e gusci interi di numerose specie di bivalvi e di gasteropodi. la componente bioclastica attribuibile ai molluschi, pur non costituendo elevate percentuali nei singoli campioni, riveste una notevole importanza data la sua distribuzione in tutta la piattaforma. anche i foraminiferi fanno parte dei più importanti gruppi di organismi che contribuiscono alla produzione dei sedimenti carbonatici, in particolare nelle componenti sabbiose medio-fini della piattaforma intermedia ed esterna. sono presenti soprattutto le forme bentoniche tra le quali è facilmente riconoscibile la miniacina miniacea, che forma sulle posidonie colonie irregolarmente ramificate simili a quelle dei briozoi e dal tipico colore rosso, e diverse specie di miliolidae anch’esse molto frequenti. le textulariidae, talvolta molto abbondanti, sono riconoscibili per il tipico guscio agglutinato biseriale. nei sedimenti delle parti distali aumentano progressivamente i foraminiferi planctonici. un altro importante gruppo di organismi biocostruttori è costituito dai briozoi, le cui colonie ricoprono diversi tipi di substrato e di organismi tra i quali le varie parti delle piante di posidonia. nei sedimenti si riconoscono facilmente le colonie a struttura reticolata (cellopora pumicosa, sertella septentrionalis, schizobranchiella sanguinea), da quelle a struttura radiale come la lichenopora radiata, e frammenti di specie ramificate (myapora truncata). gli echinodermi, regularia e irregularia, sono presenti in diversi vagli granulometrici come frammenti di gusci e, nelle frazioni più fini, radioli degli irregolari. l’aspetto e le dimensioni dei bioclasti permettono di distinguere tra i regularia prevalentemente il paracentrotus lividus e tra gli irregularia l’echinocyamus pusillus spesso in associazione con alghe rosse e briozoi, lo schizaster canaliferus, abbondante nei substrati fangosi a diverse profondità, e lo spatangus purpureus. altre componenti sono rappresentate in genere nelle granulometrie comprese tra 125 e 500 µm da ostracodi, in percentuali nettamente subordinate rispetto al volume totale dei carbonati, e da piccoli organismi a guscio chitinoso-proteico. data la complessità dell’ecositema, questo elenco comprende solo i più importanti gruppi di bioclasti riconosciuti nei campioni senza escludere la presenza di altri organismi biocostruttori identificabili in altre parti della piattaforma e/o riconoscibili in uno studio specialistico. 5. facies deposizionali comparando le facies ecografiche con i risultati delle analisi dimensionali e composizionali dei sedimenti campionati si è giunti alla individuazione di 8 gruppi di litofacies, rappresentative dell’associazione di facies deposizionali dell’attuale piattaforma del golfo di cagliari (tab. 2; figg. 7 e 8). 5.1 facies silicoclastiche prossimali in questo gruppo vengono comprese le facies di foreshore e di shoreface superiore, cioè dalla battigia all’inizio delle posidonie, presenti nel golfo di quartu e nella sua prosecuzione fino alla piattaforma del sarrabus. dal punto di vista granulometrico i sedimenti hanno generalmente una moda compresa negli intervalli delle ghiaie (granule), delle sabbie molto grosse (fig. 7a) e delle sabbie grosse che nelle spiagge più protette, o per selezione eolica, possono arrivare alle sabbie fini-molto fini. la composizione del sedimento è quasi esclusivamente terrigena (quarzoso-arcosica). la componente bioclastica si limita a frammenti di molluschi perché il moto ondoso domina ostacolando la vita degli organismi, mentre la scarsa componente fine viene allontanata verso settori più distali. i campioni prelevati lungo la costa orientale hanno una composizione mineralogica che deriva direttamente dal substrato granitoide ampiamente affiorante nell’horst del sarrabus. nella spiaggia del golfo quartu i sedimenti, che mostrano maggiori indici di maturità tessiturale e composizionale, provengono invece dalle arenarie e marne arenacee mioceniche che affiorano a est di cagliari, quindi derivano anch’essi dal basamento metamorfico e granitoide del sarrabus, ma tramite più cicli deposizionali che possono risalire fino al paleogene. le composizioni presentano un’alta percentuale in quarzo, generalmente superiore al 45%, una percentuale associata di feldspati e una componente litica nelle code ghiaiose. si associa inoltre una modesta quantità di biotiti e di altri minerali accessori. alcune eccezioni sono rappresentate dalle sabbie fini, campionate in località torre delle stelle (rc7 e rc8), ad abbondanti miche e minerali femici derivati probabilmente da locali affioramenti di rocce basiche, oltre a una componente bioclastica fino a circa il 10% di alcuni campioni. il limite batimetrico inferiore attribuito a questo gruppo di facies è individuato, nelle registrazioni ecografiche, dalla presenza continua delle posidonie che segna l’inizio della sedimentazione bioclastica. 5.2 facies quarzoso-bioclastiche dello shoreface di s. gilla nel foreshore-shoreface del settore occidentale del golfo sono presenti sabbie quarzose fini e molto fini, indici di un ambiente di spiaggia a bassa energia. infatti, questa parte del golfo, oltre a essere protetta dal contorno della costa, si avvale dell’attenuazione delle tempeste dei quadranti meridionali operata dal banco della media piattaforma. grazie a tale bassa energia, a pochi metri di profondità lo shoreface è stabilizzato da una prateria di basse fanerogame (cimodocea nodosa, posidonia oceanica) e alghe verdi (caulerpa prolifera, codium fragile e codium bursa) che precede internamente la prima fascia a posidonie. la composizione dei sedimenti è prevalentemente terrigena con circa il 50% di quarzo che proviene dagli apporti fluviali del graben del campidano, mentre la componente bioclastica si 210 l. lecca et al. 211 g r u p p i d i f a c ie s a m b ie n t e e p r o c e s s i d o m in a n t i g r a n u l o m e t r ia c o m p o s iz io n e (v e d i t a b . 1 ) s il ic o c l a s t ic h e p r o s s im a l i (q u a r z o s o f e l d s p a t ic h e ) 0 -1 4 m q u a r z o s o b io c l a s t ic h e d i s .g il l a 0 -6 m l it ic o b io c l a s t ic h e d i p u n t a z a v o r r a 0 -6 ,5 m c a l c l it it ic h e d i c a p o s . e l ia 0 -5 m f a n g o s e a l a m e l l ib r a n c h i 8 -2 7 m m is t e b io c l a s t ic o t e r r ig e n e 1 5 -5 0 m a d a l g h e r o s s e e f o r a m in if e r i 5 0 -7 5 m d is t a l i a l a m e l l ib r a n c h i e f o r a m in if e r i 7 5 – 1 1 0 m depressione interna banco a posidonia piattaforma esterna pendio esterno fascia a sand waves paleo cordone (55-60 m) foreshore -shoreface s ab b ie g hi ai o se m o lto g ro ss eg ro ss e ch e p as sa no a sa b b ie f in im o lto f in i ne lla p ar te o cc id en ta le ( p o et to p re r ip a sc im e n to ). l e g ra n u lo m e tr ie m a g g io ri s i ris co nt ra no i n b at tig ia e i n p ro ss im ità d el la c o st a. i se d im e n ti a t e rr a s o n o d a b e n e a d is c re ta m e n te cl as sa ti ( 0 ,3 5 < σ φ < 0 ,8 0 ) sa lv o r ar e ec ce zi o n i, i ca m p io ni in m ar e so no d is cr et am en te c la ss at i. s ab b ie q u ar zo se f in i e m o lto f in i si d ep o n g o n o i n co n d iz io n i d i m o to o n d o so d i b as sa e n er g ia . m o d a co m p re sa t ra le s ab b ie f in i e m o lto f in i ( 2 5 0 ÷ 6 3 µ m ). l e sa b b ie so n o d a d is cr et am en te a m ed io cr em en te c la ss at e. s ab b ie g ro ss e o m o lto g ro ss e co n d is cr et a co m p o n en te g h ia io sa . d a d is c re ta m e n te a m e d io c re m e n te c la s s a te (0 ,7 5 < σ φ< 1 ,0 5 ) s ed im en ti a m o d a co m p re sa n el le s ab b ie m ed ie e fin i d a b en e a d is cr et am en te c la ss at i (0 ,3 5 < σ φ < 0 ,7 0 ). c o m p o n en te s ili co cl as ti ca d o m in an te n eg li in te rv al li d el le c la ss i fin i e m o lto f in i. c o m p o n en te c a lc lit it ic a e sp re ss a n e lle f ra zi o n i d e lle s a b b ie m ed ie e f in i. c ur ve g ra nu lo m et ric he a d a nd am en to i rr eg o la re , in a lc u n i c a si m a rc a ta m e n te b im o d a li o p o lim o d a li, c o rr is p o n d e n ti a s e d im e n ti p o c o /m e d io c re m e n te cl as sa ti. i c am p io ni c o m p le ta m en te f an g o si r is ul ta no c er ni ti (t 8c 4, t 6c 6) . le f ra zi o ni a d ia m et ro m ag g io re s o n o r ap p re se n ta te d a fr am m en ti d i g u sc i d i o rg an is m i b en to n ic i. l e fr az io n i fin i so n o q u ar zo se co n su b o rd in at a co m p o ne nt e b io cl as tic a. c u rv e g ra n u lo m et ri ch e ad a sp et to ir re g o la re , ta lv o lta b im o d al i (t 6 c 7 e t 8 c 6 ). l a co m p o n en te t er ri g en a r in ve n u ta n e lle f ra zi o n i p iù g ro ss e è r e lit ta . s ed im en ti n el c o m p le ss o m ed io cr em en te o p o co cl as sa ti (0 ,8 5 < σ φ < 1 ,5 0 ) co n a b b o n d an te s ilt c ar b o n at ic o ( n o n è d a es cl u d er si u n le g g er o in cr em en to d i t al e fr az io n e d o vu to a f ra n tu m az io n e m ec ca n ica in f as e d i s et ac ci at u ra ). l e cl as si p iù r ap p re se n ta te s o n o q u el le d el le s ab b ie g ro ss e e m o lto g ro ss e (d a 2 0 0 0 a 5 0 0 _ m ) b en ch é il se d im en to r is u lti d is tr ib u ito in u n a m p io s p et tr o ( tr a -1 φ e 2 φ ). p re se n za d i a b b o n d an te fr az io n e fin e ca rb o n at ic a. c la ss at u ra m ed io cr e (0 ,9 0 < σ φ < 1 ,2 5 ). s ab b ie f in i e m o lt o f in i co n d is cr et a co m p o n en te fa n g o sa . c la ss i g ra n u lo m et ri ch e m ag g io ri r ap p re se n ta te d a p ic co le c o n ch ig lie d i b iv al vi c h e d an n o lu o g o a u n s e d im e n to , n e l c o m p le ss o m e d io c re m en te c la ss at o (0 ,7 5 < σ φ < 1 ,1 5 ). f ac ie s si lic o cl as tic h e s il ic o c l a s t ic o : q u ar zo , fe ld sp at i (d al la a lte ra zi o n e d ei g ra n iti ), lit o cl as ti d el b as am en to e rc in ic o . b io c l a s t ic o : lim ita to a p ic co le c o n ch ig lie d i g as te ro p o d i e a fr am m en ti d i g u sc i d i b iv al vi . f ac ie s m is te , si lic o cl as tic h e e in s u b o rd in e ca rb o n at ic h e s il ic o c l a s t ic o : q u ar zo a s p ig o li vi vi ( 5 0 % o p iù ), fe ld sp at i e lit o cl as ti. b io c l a s t ic o c ir ca 1 5 -2 0 % : m o llu sc h i e in s u b o rd in e : fo ra m in if e ri , e c h in id i ir re g o la ri ( ra d io li e f ra m m e n ti d i g u sc i), b ri o zo i, sp ic o le d i s p u g n e si lic ee . f ac ie s m is te , lit o cl as tic o -b io cl as tic h e s il ic o c l a s t ic o : l it o cl as ti a n d es it ic i, q u ar zo e f el d sp at i a e le va to g ra d o d i a rr o to n d a m e n to . b io c l a s t ic o : p ic c o li g as te ro p o d i; la m el lib ra n ch i; co m p o n en te s u b o rd in at a: r ad io li e fr am m en ti d i ec h in id i, fr am m en ti al g al i, b ri o zo i, p ic co li cr o st ace i. f ac ie s ca lc lit iti co -s ili co cl as tic o -c ar b o n at ic h e c a l c l it it ic o : cl as ti d i c al ca ri m io ce n ic i s il ic o c l a s t ic o : q u ar zo e f el d sp at i. b io c l a s t ic o : m o llu sc h i, f o ra m in if e ri b e n to n ic i, b ri o zo i, ra d io li d i e ch in id i. f ac ie s m is te s ili co cl as tic o -c ar b o n at ic h e s il ic o c l a s t ic o : q u ar zo a s p ig o li vi vi e f el d sp at i. b io c l a s t ic o : b iv al vi e g as te ro p o d i. f ra zi o n e o rg a n ic a : re si d u i d i p o si d o n ia i n c o n c e n tr a zi o n i im p o rt a n ti n e lle f ra zi o n i fi n i. g ra n u li d i o ri g in e a n tr o p ic a : sc ar ti d a n av i a v ap o re e r ar i a g g re g at i b itu m in o si . f ac ie s m is te s ili co cl as tic o -c ar b o n at ic h e b io c l a s t ic o : m o llu sc h i ( va ri e sp ec ie d i l am el lib ra n ch i e p ic c o li g a st e ro p o d i), b ri o zo i, fo ra m in if e ri b e n to n ic i e s va ri a te sp ec ie d i o rg an is m i d el la b io ce n o si a p o si d o n ia . s il ic o c l a s t ic o : q u ar zo e f el d sp at i in g ro ss i in d iv id u i e n el le f ra zi o n i fin i, ar en ar ia c em en ta ta , fr am m en ti lit o cl as tic i d el b as am en to m et am o rf ic o . il te rr ig en o d im in u is ce n el p en d io in fe ri o re . f ac ie s ca rb o n at ic h e. a ss o ci az io n e fo rm at a d a u n a co m p o n en te i n d ig en a co st itu ita in p re va le n za d a al g h e ro ss e ca lc ar ee , e d a co m p o n en ti p ro ve n ie n ti d al la p ar te p iù e le va ta d el b an co a p o si d o n ia . b io c l a s t ic o : al g h e ro ss e ca lc ar ee r am ifi ca te e in cr o st an ti, m o llu sc h i, fo ra m in ife ri b en to n ic i, fr am m en ti d i e ch in id i, b ri o zo i. p ic co le p er ce n tu al i d i t er ri g en o r el itt o ( ca m p io n i t 6 c 8 , t 8 c 7 e t 9 c 6 ) n o n t al e d a ca ra tt er iz za re d el le f ac ie s m is te . f ac ie s m is te . b io c l a s t ic o : b iv al vi , fo ra m in ife ri p la n ct o n ic i e b en to n ic i. s u b o rd in at i: b ri o zo i, fr am m en ti d i g u sc i e ac u le i d i ec h in id i i rr eg o la ri . s il ic o c l a s t ic o : q u ar zo a s p ig o li vi vi , m in er al i a cc es so ri c o m p o n en te a u tig en a: g la u co n ite ( m o d el li in te rn i d i fo ra m in ife ri ). f o re sh o re e sh o re fa ce su p er io re d el s et to re o ri en ta le d el g o lfo e sp o st o a l m o to o n d o so e a lle c o rr en ti d a es so i n d o tt e ch e se le zi o n an o e r im an eg g ia n o i s ed im en ti. f o re sh o re e sh o re fa ce s u p er io re d el s et to re o cc id en ta le d el g o lfo p ro te tt o d al le m as si m e in te n si tà d el m o to o n d o so . l e co n d iz io n i d i sc ar so i d ro d in am is m o fa vo ri sc o n o la p re se n za d i i n fa u n a e fa u n a b en to n ic a ch e p ro d u co n o u n im p o rta n te v o lu m e d i b io cl as ti. l a b as sa i n te n si tà d el m o to o n d o so i n d u ce l im ita to tr as p o rt o e s ca rs a se le zi o n e. b as e d i f al es ie w av e d o m in at ed . c o p er tu re s ed im en ta ri e d is co n tin u e si d ep o n g o n o s u f o n d al i ro cc io si a lla b as e d el le f al es ie d el le a n d es iti o lig o -m io ce n ic h e d i p .t a z av o rr a so g g et te a f o rt e m o to o n d o so ). i l su b st ra to è c o lo n iz za to i rr eg o la rm en te d a m at te s is o la te d i p o si d o n ia o ce an ic a; i se d im en ti si a cc u m u la n o al l’i n te rn o d i p ic co le d ep re ss io n i e ro si o n al i.. o rg an is m i a g g lu tin an ti e in cr o st an ti g en er an o in cr o st az io n i e a g g re g at i d i f ra m m en ti lit ic i, ra d io li e al tr i b io cl as ti. b as e d i f al es ie w av e d o m in at ed . s ed im en ti d is co n tin u i d el f o re sh o re e s h o re fa ce d el la p ic co la s p ia g g ia d i c al a m o sc a al la b as e d el le f al es ie d el le c o lli n e ca lca re e d i c ap o s . e lia , ca ra tt er iz za ti d al la p re se n za d i a b b o n d an ti cl as ti ca lc ar ei . l e co n d iz io n i id ro d in am ic h e al l’i n te rn o d el la b ai a so n o p ro te tt e m en tr e al tr o ve l’e n er g ia d el m o to o n d o so è e le va ta . r ap id o d ec re m en to d el la c o m p o n en te ca lc lit iti ca v er so il la rg o p er l’ az io n e sc h er m an te d el la p o si d o n ia . s h o re fa ce in fe ri o re a n tis ta n te la la g u n a d i s . g ill a e d ep re ss io n e d el la p ia tt af o rm a in te rn a. c ar at te ri zz at o d a al te rn an za d ep o si zi o n al e d i fa n g h i d i b el t em p o e la m in e sa b b io se d i te m p es ta . i se d im en ti d el la d ep re ss io n e p re se n ta n o u n a la m in az io n e p ia n o -p ar al le la c o st itu ita d a u n a fit ta a lte rn an za d i la m in e m ill im etr ic h e d i sa b b ia m o lto f in e e liv el li ar g ill o si a d a lto c o n te n u to i n m at er ia o rg an ica . f en o m en i d i c o st ip az io n e d el s ed im en to e f er m en ta zi o n e an ae ro b ic a. b as se e n er g ie id ro d in am ic h e p er p ro fo n d ità in fe ri o ri a lla b as e d el m o to o n d o so d i b el t em p o e d i t em p es ta . b an co d i m ed ia p ia tt af o rm a. f as ci a a p ro d u zi o n e ca rb o n at ic a co n p re se n za d i se d im en ti te rr ig en i r el itt i e d i s u b o rd in at i a p p o rt i t er ri g en i a tt u al i. t ra n si zi o n e tr a la p ra te ri a a ca n al i e q u el la c o n tin u a co n tr o lla ta d al l’i d ro d in am is m o d el m o to o n d o so d i t em p es ta . c o n tr o llo d el la s ed im en ta zi o n e d a p ar te d ei f at to ri b io lo g ici : p ro d u zi o n e d i se d im en to c al ca re o e i n tr ap p o la m en to n ei r iz o m i e ra d ic i d el le p o si d o n ia d ei s ed im en ti ca lc ar ei e t er ri g en i. i ca m p io n am en ti co n b en n a n o n s em p re s o n o p o ss ib ili p er l’ in te g ri tà d el la p ra te ri a. p ia tt af o rm a in te rm ed ia d is ta le e d e st er n a. a re al e si tu at o o ltr e il lim ite e st er n o d el la p ra te ri a, in u n a fa sc ia c h e si e st en d e d al la b at im et ri a in iz ia le d i c ir ca 4 5 m . p ro d u tt iv ità o rg an o g en a lim ita ta a d a re e n o n s ta b ili e d is co n tin u e. r im an eg g ia m en to o p er at o d al m o to o n d o so d i te m p es ta ; am b ie n te i d ro d in am ic o n el co m p le ss o a s ca rs a ca p ac ità s el et tiv a (a b b o n d an te m at er ia le a g ra n u lo m et ri a fin e) . e vi d en ze s u i g ra n u li, d i e p is o d i d i a lte rn i s ep p el lim en ti e su cc es si ve m o b iliz za zi o n i. s u l p al eo c o rd o n e si s vi lu p p an o d ei c al ca ri o rg an o g en i p re va le n te m en te a d a lg h e ro ss e a co st itu ir e lo ca lm en te d ei p in n ac o li. l a fin e d el la c o m p o n en te a lg al e e la p re se n za d i se d im en ti p iù f in i a m at ri ce fa n g o sa d el im ita v er so il la rg o la t ra n si zi o n e al la s u cc es si va z o n a d i f ac ie s. p ia tt af o rm a es te rn a. f as ci a b at im et ri a al d i s o tt o d el la b as e d el m o to o n d o so d i te m p es ta a d ec an ta zi o n e fa n g o sa . p ro d u tt iv ità o rg an o g en a ra p p re se n ta ta d a la m el lib ra n ch i, fo ra m in ife ri s ia b en to n ic i ch e p la n ct o n ic i ed e ch in id i ir re g o la ri (m in o ri ). a lt a co n ce n tr az io n e d i q u ar zo e m in er al i p es an ti n el le f ra zi o n i fin i. p re se n za in o ltr e d i m in er al i a u tig en i. t a b . 2 s in te si d e g li a m b ie n ti e d e lle f a c ie s d e p o si zi o n a li d e lla p ia tt a fo rm a d i c a g lia ri . ke tc h o f e n vi ro n m e n ts a n d d e p o si ti o n al f ac ie s o n t h e s h e lf o f th e g u lf o f c ag lia ri . i sedimenti terrigeno carbonatici ... 212 attesta, nei campioni prelevati sulla battigia, intorno al 10÷15% e nei campioni di spiaggia sommersa al 30% circa del totale, fino a circa il 45% nel campione t8c1. i bioclasti sono in prevalenza gusci di molluschi (lamellibranchi e gasteropodi), talvolta sub-attuali calcitizzati e sepolti da sabbie siltose nerastre. si ritrovano inoltre radioli e frammenti di gusci di echinidi irregolari, briozoi, foraminiferi e, nelle frazioni di diametro minore, rare spicole di spugne silicee. sempre in relazione con la bassa energia, nei campioni più distali di tale gruppo di facies è spesso presente una componente organica costituita da frammenti di foglie di posidonia. tale componente nel campione t6c3 arriva fino a circa il 30% (stima areale al binoculare) nella frazione 500÷250 µm, nel t7c2 il al 30% nella frazione 250÷125 µm e nel t7c3 al 20% nelle frazioni 1000÷500 µm. 5.3 facies litico-bioclastiche di punta zavorra nei pressi di punta zavorra si osservano facies poligeniche con componente litoclastica e bioclastica. il fondo marino è in prevalenza roccioso (andesiti) e i sedimenti si accumulano all’interno di concavità erosionali che si alternano a mattes isolate di posidonia. i sedimenti sono rappresentati da sabbie grosse o molto grosse con una discreta componente ghiaiosa. nella battigia predomina la componente litoclastica (85%), mentre in mare predomina la componente bioclastica (50÷60% circa). i clasti litici, in genere arrossati, provengono dall’erosione delle andesiti oligoceniche e dei depositi quaternari esposti in falesia, e indirettamente dal basamento dell’horst del sulcis. nettamente subordinati sono i piccoli granuli di quarzo a spigoli vivi, che diventano relativamente importanti nelle frazioni a granulometria minore. la componente bioclastica è composta prevalentemente da piccoli gasteropodi, mentre i lamellibranchi sono meno rappresentati. inoltre sono presenti radioli e frammenti di gusci di echinidi e, in misura subordinata, frammenti algali, briozoi e chele di piccoli crostacei, oltre a incrostazioni e particelle aggregate per opera di vermi. 5.4 facies calclititiche di capo s. elia attorno al capo s. elia e soprattutto all’interno dell’insenatura di cala mosca è presente un gruppo di facies terrigene a componente calclititica. sulla battigia le sabbie sono grosse e composte prevalentemente da granuli calcarei poco elaborati, provenienti dall’erosione fig.7 principali litofacies: a) campione t3c2: sabbie ghiaiose silicoclastiche di shoreface; b) campione t4c6 misto bioclastico-terrigeno del pendio esterno del banco a posidonia; c) campione t3c5 in facies ad alghe rosse e foraminiferi; d) campione t7c5 misto alla transizione della depressione ovest col banco principale, frazione 250÷125µm: nel riquadro granuli fecali isolati. la barra di scala è lunga 5 mm in a, b, c e 1 mm in d. ubicazione in fig. 3. main lithofacies: a) sample t3c2: shoreface siliciclastic gravelly sands; 2) sample t4c6: bioclastic-terrigenous gravelly sand of the outer slope of the posidonia bank; 3) samplet3c5: red algae and foraminifers facies; 4) sample t7c5 in western trough, fraction 250÷125µm: in square selected fecal-pellets. bar scales are 5 mm in length for a, b, c and 1 mm for d. for locations see fig.3. l. lecca et al. 213 delle falesie dove affiora una sequenza del miocene superiore costituita da calcari a lithotamnium, assieme a calcari marnosi e in subordine areniti quarzoso-feldspatiche debolmente cementate (leone et al., 1992). questa componente litica subisce un rapido calo spostandosi verso il largo con l’instaurarsi dei banchi di posidonie, presenti già a poca distanza dalla riva. la componente terrigena è in parte quarzosa (fino al 45% in t5c2) con granuli di dimensioni minori rispetto a quelli calclititici. la componente bioclastica è decisamente subordinata in battigia (circa 1% del totale) ma acquista maggiore importanza a qualche metro di profondità (circa 10%). tale componente è costituita da molluschi (compresi vermetidi), briozoi, radioli di echinidi, foraminiferi bentonici e ostracodi. la materia organica, come frammenti di fanerogame ed alghe di bassa profondità, è talvolta presente in quantità importante. 5.5 facies fangose a lamellibranchi dello shoreface inferiore antistante s. gilla e della depressione della piattaforma interna la depressione interna, rispetto allo shoreface superiore e al banco principale della prateria a posidonie, è un ambiente a bassa energia dove si depongono in prevalenza sabbie fini e fanghi. le curve granulometriche hanno un andamento irregolare, in alcuni casi sono marcatamente bimodali o polimodali. questo carattere è dovuto alla presenza di gusci provenienti da infauna e fauna bentonica che colonizzano il fondale fangoso. inoltre nel campione t6c5 si trovano ciottoli fluviali relitti che documentano una sedimentazione tardo-olocenica-attuale discontinua che, in aree limitate, lascia esposti sedimenti più antichi. le sabbie fini e molto fini quarzose presentano una componente organica di frammenti di posidonia, oltre a gusci di lamellifig.8 zonazione delle facies deposizionali della piattaforma del golfo di cagliari. depositional facies on the shelf of the gulf of cagliari: 1 ) quartzose-bioclastic facies of s. gilla’s shoreface; 2) terrigenous facies of quartu’s shoreface and sarrabus’ shelf; 3) p.ta zavorra lithic-bioclastic facies; 4) cape s. elia calci-lithic arenite facies; 5) sandy-muddy bivalve bearing facies of the lower western shoreface; 6) muddy facies with bivalves of the western inner shelf’s trough; 7) mixed bioclastic-terrigenous facies of the eastern shelf’s trough; 8) middle-shelf mixed bioclastic-terrigenous facies; 9) red algae and foraminifers facies; 10) distal facies with bivalves and foraminifers; 11) paleo shore-line; 12) shelfbreak. i sedimenti terrigeno carbonatici ... branchi e a una componente bioclastica. l’importanza dei frammenti di posidonie, è stata quantificata per stima areale nei campioni t7c3 (30% nelle frazioni 2000÷250 µm), t7c4 (60% tra 2000÷1000 µm, 50% tra 1000÷500 µm e 30% tra 500÷250 µm), t7c5 (20% tra 500÷250 µm) e t6c5 (5% tra 250÷125 µm). in t7c4 si riscontrano rari pirosseni e biotiti attribuibili a una piccola componente andesitica proveniente da punta zavorra o altri affioramenti di andesiti (fig. 1). si ritrovano infine materiali di origine antropica, probabili scarti di combustione di navi a vapore che stazionavano in rada. questa zona del golfo di cagliari anche ai nostri giorni è infatti interessata da ancoraggi di navi commerciali. a tal proposito si segnala in questo gruppo di facies così come nello shoreface di s.gilla la presenza di rari granuli aggregati da bitume. le facies più fangose sono rappresentate dai campioni t6c6 e t8c4 nei quali tutto il materiale passa al vaglio dei 63 µm. questi fanghi danno una discreta effervescenza all’hcl per cui la parte carbonatica è stata valutata mediante calcimetria intorno al 20%. al microscopio è visibile, dopo un attacco con hcl, molta materia organica, particelle siltose di vario aspetto e una componente argillosa terrigena (argille e materiale organico = 43,0%). infatti questa zona del golfo è soggetta all’accumulo dei sedimenti più fini degli eventi di piena del rio mannu e del cixerri, le cui torbide si è constatato che raggiungono quasi tutta la parte occidentale della piattaforma. il materiale bioclastico è costituito per lo più da grossi lamellibranchi come mitilidi, pettinidi e cardidi e subordinati gasteropodi. la parte restante è costituita da foraminiferi, briozoi, radioli di echinidi, rari noduli algali e numerosi fecal pellets (fig. 7d). questi ultimi hanno dimensioni variabili tra 500÷125 µm e sono costituiti da fango terrigeno-carbonatico e materia organica. i sedimenti mostrano, al momento del prelievo (la benna ha campionato fino a circa 20 cm sotto la superficie del fondo), una tipica struttura costituita da una fitta alternanza di lamine millimetriche di sabbia molto fine e argille nere. inoltre la parte interna di alcuni bioclasti si presenta annerita a causa del seppellimento nel fango. questi elementi documentano che tale facies laminata è attribuibile all’alternanza di fanghi di bel tempo, ricchi di materia organica, con lamine sabbiose di tempesta, e che in questo ambiente si instaurano precocemente condizioni riducenti subito al di sotto dell’interfaccia acqua-sedimento. 5.6 facies miste bioclastico-terrigene sedimenti misti bioclastico-terrigeni sono presenti in piattaforma intermedia nel banco principale a posidonia e nel pendio esterno al banco. l’ambiente deposizionale di questo gruppo di facies corrisponde circa all’areale dell’offshore superiore (15÷50 m circa). i sedimenti sono mediocremente classati (fig. 7b), talvolta bimodali (t6c7 e t8c6), prevalentemente distribuiti nelle classi delle sabbie grosse e molto grosse (2000-500 µm), con una discreta coda fine. generalmente il bioclastico prevale sul terrigeno con percentuali del 60÷70%, ma talvolta è subordinato con valori del 30÷40%. la componente bioclastica è dominata dai molluschi, mentre nella parte distale assumono maggiore rilevanza i frammenti di alghe rosse. inoltre risulta importante la presenza di briozoi, tra i quali sono stati riconosciuti cellepora pumicosa e lichenopora radiata, e di numerosi foraminiferi bentonici di dimensioni fino a 1000 µm. è da notare la frequente presenza di miniacina miniacea, che vive sulle radici e rizomi esposti delle posidonie. in quantità subordinata si rinvengono radioli o frammenti di gusci di echinidi, alcuni piccoli crostacei e rari coralli aermatipici. la componente silicoclastica rinvenuta nella parte prossimale del banco è generalmente rappresentata da sabbie medie e fini, mentre nella parte esterna del banco e del pendio si rinvengono sabbie molto grosse debolmente ghiaiose costituite da quarzo, feldspati, litoclasti metamorfici e arenarie cementate, oltre a una subordinata coda fine quarzosa. l’origine di tale componente silicoclastica nella parte prossimale del banco (zone in cui il banco a posidonie si raccorda direttamente allo shoreface) può essere ricondotta alla attuale sedimentazione di sabbie di shoreface mobilizzate da eventi di tempesta. diversamente, nelle parti separate dalle depressioni, nel banco a posidonie e nel pendio fino a –50 m circa, la componente silicoclastica deve essere attribuita al rimaneggiamento e risedimentazione di sedimenti relitti presenti in questa parte di piattaforma. questi sedimenti, sulla base del grado di elaborazione e della presenza di granuli di arenarie cementate senza matrice possono essere attribuiti in parte a paleo spiagge, e in parte, per la presenza di granuli cementati da matrice arrossata, a paleo depositi continentali (probabilmente fluviali o colluviali). l’analisi dei diversi profili ecografici eseguiti mostra che il banco costituisce una struttura continua trasversale a tutto il golfo, pur presentando areali a diversa tipologia. purtroppo in questa zona spesso la benna non ha prelevato alcun sedimento a causa della continuità delle posidonie; pertanto per una migliore descrizione della sedimentazione relitta si rimanda successive campionature. 5.7 facies ad alghe rosse e foraminiferi queste facies compaiono nella parte più esterna del pendio del banco a posidonia, cioè lungo la fascia delle sand waves, e sui fondali pianeggianti fino alla transizione verso la piattaforma esterna (offshore superiore-offshore inferiore). il sedimento è costituito da una componente indigena ad alghe rosse e foraminiferi, e da sedimenti alloctoni provenienti dal pendio esterno del banco. la composizione è quasi esclusivamente bioclastica (fig. 7c) ma verso terra si osserva una transizione graduale con le facies miste. l’andamento delle curve granulometriche mostra una moderata uniformità tra tutti i campioni prelevati; gli intervalli più rappresentati sono quelli delle sabbie grosse e molto grosse (da 2000 a 500 µm), benché il sedimento risulti distribuito in un intervallo tra le ghiaie e i fanghi. l’importante presenza di una coda di sabbia molto fine fango carbonatico documenta l’ambiente distale a bassa energia. la componente predominante è costituita da grossi frammenti algali prevalentemente ramificati (lithophyllum racemus) e altre forme indeterminate loose branching (sensu johnson 1962 e johnson & adey, 1965) di pochi millimetri. seguono per importanza i foraminiferi, frammenti di molluschi, di echinidi e, in subordine, briozoi. la fauna bentonica si sviluppa probabilmente su zone in rilievo e in substrati semi stabili 214 l. lecca et al. dove le alghe rosse si rinvengono regolarmente vive e lasciano supporre un ampio areale di distribuzione. questo gruppo di litofacies si riscontra a cavallo della paleo-riva dei –55 m al di sopra della quale, talvolta nella parte orientale, le linee ecografiche evidenziano la presenza di pinnacoli algali. il limite batimetrico inferiore di queste facies è stato ubicato, indicativamente in base ai profili ecografici, lungo i fondali pianeggianti a sedimentazione fangosa della piattaforma esterna. tali facies, campionate maggiormente nella zona “a” di figura 3, saranno descritte con maggior dettaglio in successive fasi di questa ricerca. 5.8 facies distali a lamellibranchi e foraminiferi le campionature tuttora in corso nel settore occidentale del golfo hanno permesso di riconoscere, nella parte più esterna della piattaforma (–75÷–110 m), la transizione ad una fascia a sedimentazione sabbiosa fine e fangosa mista quarzoso-bioclastica. la produttività organogena è rappresentata da piccole conchiglie di bivalvi, foraminiferi sia bentonici che planctonici e in minor quantità da echinidi irregolari. la componente silicoclastica è rappresentata da sabbie fini quarzose a spigoli vivi. inoltre è presente una discreta concentrazione di minerali autigeni, accresciuti all’interno di foraminiferi, e altri minori indeterminabili. 6. modello deposizionale tardo olocenico–attuale della piattaforma di cagliari 6.1 ambienti e processi la piattaforma del golfo di cagliari si delinea come un sistema sedimentario complesso, sede di processi deposizionali controllati da diversi tipi di fattori sedimentologici. il regime idrodinamico è quello di uno shelf wave-dominated “attenuato”, essendo il golfo esposto alle sole mareggiate dai quadranti meridionali e ridossato rispetto a quelle dei quadranti occidentali (serra, 1971; istituto idrografico della marina, op. cit.), infatti le posidonie riescono a prevalere nella piattaforma intermedia, diversamente a quanto avviene nella sardegna occidentale dove le frequenti tempeste da nordovest danno luogo ad una piattaforma tipicamente wave-dominated (carboni et al., 1989). gli apporti terrigeni sono scarsi mentre, in piattaforma intermedia, una importante produttività carbonatica si sovrappone a sedimenti di precedenti cicli deposizionali a controllo eustatico. il risultato è quello di una piattaforma mista terrigeno-carbonatica organizzata in un sistema di ambienti documentati dalla presenza dei diversi gruppi di facies deposizionali (tab. 2 e fig. 9). ambiente transizionale le più complete sezioni della piattaforma mostrano una transizione all’ambiente estuarino costituita da una laguna microtidalica, schizoalina, separata dal dominio marino mediante la discontinua barriera sabbiosa attuale. questo ambiente, non descritto in questo studio, deve essere considerato integrante del sistema della piattaforma continentale per gli apporti terrigeni estuarini che alimentano lo shoreface, per i controlli marini che subisce attualmente da parte delle tempeste, per la produttività bioclastica salmastra (cottiglia 215 f ig .9 a m b ie n ti e m o d e llo d e p o si zi o n a le d e lla p ia tt a fo rm a d i c a g lia ri . s e zi o n e r ic o st ru it a s u lla b a se d i u n p ro fil o s p ar ke r 5 0 0 j e d iv e rs e li n e e e c o g ra fic h e : il p ro fil o m o st ra le s e q u e n ze d e p o si zi o n a li p re c e d e n ti l’ u lt im o m in im o g la c io -e u st a ti c o d e i 1 8 ÷ 2 0 k a ( g ri g io c h ia ro ) e la s e q u e n za d i t ra sg re ss io n e e d i a lt o e u st a ti c o p o st -g la c ia le ( g ri g io s c u ro ). u b ic a zi o n e in f ig . 3 . e n vi ro n m e n ts a n d d e p o si ti o n al m o d e l o f th e s h e lf o f c ag lia ri . in te rp re ta ti ve c ro ss -s e c ti o n o f a 5 0 0 j s p ar ke r p ro fil e a n d o f se ve ra l e c o g ra p h ic l in e s o f th e w e st e rn s e c to r o f th e g u lf. l ig h t g re y: p re 1 8 ÷ 2 0 k a se d im e n ts , d ar k g re y: p o st 1 8 ÷ 2 0 k a se d im e n ts . f o r lo c at io n s e e f ig .3 . i sedimenti terrigeno carbonatici ... et al., 1973) e infine perché durante gli stazionamenti alti quaternari è stata sede dei più interni coastal onlap. rispetto all’attuale piattaforma tale ambiente viene pertanto considerato come un paleo shore-shorefacedepressione interna della piattaforma quaternaria durante le fasi di massimo eustatico come per esempio è stato durante il tirreniano (mis 5, marine isotope stage 5 sensu martinson et al., 1987; pecorini, 1986). shoreface superiore la sedimentazione in shoreface è generalmente fining basinward con sabbie grosse in prossimità della battigia, dove dominano le strutture a ripples da onda di bel tempo, e fini verso le depressioni della piattaforma interna. il profilo complessivo è quello di un corpo sabbioso ampio da qualche decina fino a diverse centinaia di metri, debolmente convesso. attualmente questo ambiente mostra condizioni instabili, anche se i bilanci volumetrici totali sono difficilmente valutabili; il foreshore, che costituisce l’elemento maggiormente osservabile, mostra in tempi storici arretramenti per cause globali e probabilmente anche per cause antropiche locali. la produttività carbonatica si evidenzia nella parte distale dei fondali sabbiosi e con l’inizio delle posidonie, che nelle linee ecografiche può essere ubicato a profondità di –4÷8 m nel settore orientale e a circa –2÷6 m in quello occidentale, dove gli organismi crescono in condizioni idrodinamiche generalmente tranquille. nel settore orientale del golfo (spiaggia del poetto pre-ripascimento, golfo di quartu), il dinamismo del moto ondoso ostacola lo sviluppo delle praterie interne nella zona prossimale dello shoreface (<–4 ÷ –8 m). la sedimentazione bioclastica è ridotta ai clasti più grossi, mentre i più fini e/o i meno pesanti vengono allontanati verso settori più distali, dando luogo a una sedimentazione quasi completamente silicoclastica. nel settore occidentale del golfo (spiaggia della maddalena la playa) le fanerogame colonizzano le aree prossimali più protette già a pochi metri di profondità, e le sabbie presentano un’importante componente bioclastica fino a circa il 40%. infatti, l’energia in questo tratto di costa è piuttosto bassa e il substrato di sabbie fini-molto fini permette la presenza di una ricca fauna epi ed endo-bentonica di limivori e filtratori. shoreface inferiore e prateria a posidonie interna come è già stato illustrato, i profili ecografici documentano una prima prateria a posidonia, con una fascia prossimale a mattes e canali intermatte e una più profonda dove la prateria si presenta continua. i sedimenti sono silicoclastici di shoreface nella parte interna e siltosi e bioclastici nella parte più profonda di transizione alla depressione della piattaforma interna. questa colonizzazione prossimale da parte della prateria è un prezioso indicatore delle condizioni idrodinamiche e consente di ubicare, anche se in modo approssimato, la base del moto ondoso di bel tempo (fwwb) all’inizio della fascia a posidonie “continue” (fig. 5). poiché lo sviluppo della struttura a matte richiede diversi anni si deduce che questo limite non è soggetto alle fluttuazioni stagionali, ma è piuttosto da ritenersi stabile lungo un arco di tempo almeno decennale; solo durante le maggiori tempeste viene modificato e le posidonie vengono spiaggiate. sulla base dell’analisi ecografica il fwwb è ubicabile lungo il profilo t4 (settore nord-orientale del golfo) alla profondità di 12÷13 m, e a circa 7÷8 m nel profilo t6 (settore occidentale, fig 7). depressioni della piattaforma interna la piattaforma di cagliari, rispetto al resto della piattaforma sarda, è caratterizzata dalla presenza di due depressioni che si sviluppano parallelamente alla linea di costa, ubicate tra lo shoreface e il banco della piattaforma intermedia. la più importante, quella a ovest di capo s. elia e antistante la laguna di s. gilla, è colonizzata dalla prateria solo tra lo shoreface e l’offshore superiore, mentre la parte più profonda è spoglia e planare. la sedimentazione varia da un’alternanza di lamine di fango e di sabbie fini (facies fangose a lamellibranchi), a sedimenti completamente fangosi nella parte più profonda (-27 m, profilo t7; campioni t6c6, t8c4). l’idrodinamismo è molto basso grazie alla protezione data dal banco della piattaforma intermedia che accresce delimitando una zona chiusa a scarsa circolazione delle acque dove episodicamente, sul fondo, s’instaurano condizioni anossiche. l’assenza della prateria in questa parte della depressione è probabilmente riconducibile agli effetti sfavorevoli indotti dalla sedimentazione fangosa asfittica sull’apparato radicale e dal materiale fine in sospensione derivato dalle torbide fluviali argillose e dal disfacimento delle foglie delle posidonie delle zone adiacenti. in questo ambiente si individua dunque un limitato “offshore inferiore” chiuso nella piattaforma interna protetta (fig. 9), come evidenziano i fondi piani e la laminazione parallela nella parte più profonda della depressione, mentre esternamente al banco, nella parte aperta ed esposta della piattaforma, l’inizio dell’offshore inferiore (swb) si delinea a maggiori profondità, tra le sand waves e i fondi piani. i campioni più fangosi mostrano una componente carbonatica con valori di circa il 20% (da calcimetria) che si associa a una quarzosa di circa il 60% e una componente organica di circa il 10-20%. oltre a queste componenti si sottolinea la presenza di fango in granuli fecali (fig. 7d). nella depressione della piattaforma a est di capo s. elia, invece, un simile contesto deposizionale non si verifica, essendo la depressione più piccola e meno profonda (–22 m, profilo t4). l’esposizione al moto ondoso consente sia un maggior ricambio d’acqua sia l’allontanamento delle frazioni fini, pertanto i sedimenti sono più sabbiosi e le posidonie sono presenti anche nella parte più profonda. banco principale a posidonie nel golfo di cagliari, le attuali condizioni favorevoli fanno sì che le posidonie e i sedimenti associati producano un rilievo riccamente carbonatico che, non avendo una struttura interna wave resistent, viene denominato banco sensu riding (2002). il banco a posidonia si eleva di 10÷15 metri rispetto alle depressioni interne, culmina a circa –12 metri e possiede un pendio esterno, anch’esso con una importante componente carbonatica, fino alla transizione con i fondi planari esterni a circa 50 metri. il suo sviluppo occupa un’ampia fascia quasi parallela alla linea di costa che si raccorda verso ne alla piattaforma del sarrabus e verso sw a quella del sulcis meridionale e nella parte centrale al promontorio di capo s. elia. i profili ecogra216 l. lecca et al. fici evidenziano che la zona di offshore superiore, coincidente con la parte alta del banco, è completamente colonizzata dalla posidonia, come dimostrano i numerosi tentativi di campionamento non riusciti in diverse parti del banco. la prateria, pur ricoprendo in maniera omogenea dei vasti areali, presenta discontinuità e differenze di accrescimento al suo interno. la struttura a matte con pareti alte e canali intra-matte è probabilmente prodotta dalla frequente azione delle onde di bel tempo e dall’azione più intensa di quelle di tempesta. più esternamente la prateria appare più continua e caratterizzata spesso da un profilo ad ampi gradini. nelle parti distali comincia a diradarsi per poi scomparire alla profondità di circa 30 ÷ 35 m per diminuzione della luminosità. al banco si associa un’importante produttività bioclastica che si diversifica in prossimità dell’apparato radicale, nei rizomi e nelle foglie. gli abbondanti resti scheletrici carbonatici vengono intrappolati dalla prateria e colmano locali depressioni di inter o intramatte. il ruolo della prateria nel controllo della sedimentazione attuale si esplica da un lato nella produzione di materiale organico e di sedimento carbonatico-bioclastico, dall’altro nelle funzioni di consolidamento delle superfici deposizionali, che impediscono la dispersione degli apporti terrigeni al largo, e di smorzamento del moto ondoso di tempesta e delle correnti associate. lo sviluppo verticale delle mattes è relazionato al tasso di sedimentazione e può raggiungere velocità di crescita dell’ordine di 1 m/secolo (pérès & picard, 1964; riedl, 1991). i profili sparker (lecca et al., 1998) ed sbp (fig. 10) effettuati trasversalmente al banco mostrano una capacità almeno debolmente aggradante. la facies deposizionale più diffusa è quella mista bioclastico-terrigena. la componente terrigena nella parte prossimale del banco può provenire da risospensioni per tempesta di sabbie fini, mentre distalmente deve essere attribuita al rimaneggiamento di sedimenti relitti. pendio esterno del banco, settore distale a fondo planare e paleo-riva il pendio esterno del banco principale, ormai spoglio di posidonie, presenta ondulazioni del fondo disposte circa parallelamente al banco, chiaramente riconoscibili come sand waves prodotte dall’azione delle onde di tempesta sul fondale, in una fascia batimetrica compresa tra –35 e –55 metri circa. il sedimento è costituito da sabbie bioclastiche molto grosse e mal classate con matrice fangosa, testimonianti un ambiente idrodinamico attuale episodicamente trattivo. la componente bioclastica è costituita da frammenti algali (prevalentemente alghe ramificate non fissate al fondo), da briozoi, molluschi, echinidi e foraminiferi. la frazione algale è costituita soprattutto da lithophyllum racemus, oltre a lithophyllum expansum, 217 fig. 10 interpretazione sequenziale dei sedimenti che colmano la depressione occidentale della piattaforma interna. a) interpretazione dei profili 3,5 khz (contu et al.,1983; lecca et al., 1998), b) unità genetiche, fasi eustatiche e sequenziali. ubicazione in fig. 3. interpretation of 3.5 khz profiles (contu et al.,1983; lecca et al., 1998) showing: a) the genetic units and b) the sequential and eustatic stages of the western trough infilling sediments. for location see fig.3. i sedimenti terrigeno carbonatici ... peysonnelya sqamaria e vidalia volubilis, quest’ultima parzialmente calcificata. i frammenti algali appaiono spesso di colore grigio scuro testimoniando episodi di seppellimento. la componente silicoclastica relitta è stata campionata tra –30 e –50 m con percentuali decrescenti verso il largo. nella parte terminale del pendio le litofacies tendono a perdere il carattere terrigeno fino a divenire completamente bioclastiche. tenuta presente l’evoluzione paleogeografica durante la risalita olocenica, questa componente deve essere ritenuta più ampiamente disponibile e ricondotta fino alla linea di costa verso il sulcis e il sarrabus, sia verso il capo sant’elia. i tipi di granuli individuati nei sedimenti campionati (clasti litici metamorfici, granuli millimetrici di quarzo e kfeldspato e rari granuli di arenarie debolmente cementate), sono attribuibili a diverse antiche facies verosimilmente presenti attualmente sotto il banco principale delle posidonie (tra i –10 e i –50 m circa). tra le facies relitte prevalgono quelle attribuibili a depositi alluvionali e colluviali continentali, a depositi di spiaggia e in subordine a complessi dunari, come inizialmente ipotizzato da segre (1968). dall’analisi dei profili risulta che le strutture ad onde di sabbia diminuiscono gradualmente di lunghezza e altezza e aumentano di frequenza, fino a scomparire alla profondità di 55 m. in questa fascia batimetrica si osserva la transizione ai fondi planari, interrotti alla profondità di circa 55 ÷ 60 m dal paleo-cordone litorale. le alghe rosse prevalgono nettamente a profondità più basse (45÷75 m) rispetto all’areale di distribuzione delle posidonie, e si sovrappongono con queste ultime solo parzialmente a profondità minori. ciò evidenzia una possibile complementarietà con le posidonie. infatti dove le posidonie hanno il maggiore accrescimento le alghe rosse non riescono ad essere competitive, avendo una struttura scheletrica molto più bassa, mentre al diradarsi della prateria per la diminuita luminosità ne risultano avvantaggiate. in questa fascia l’idrodinamismo delle tempeste rimuove episodicamente i sedimenti algali favorendo le specie variamente ramificate dei fondi incoerenti, mentre sulla cima del paleo cordone si osservano caratteristici pinnacoli prodotti piuttosto da specie di tipo incrostanti. nonostante nella zona campionata (t7-t8) la transizione tra la zona ad alghe rosse e quella più profonda a sedimenti sabbiosi fini a lamellibranchi si verifichi esternamente alla paleo-riva, si ritiene che quest’ultima costituisca un limite fisiografico-deposizionale che dovrà essere meglio definito dal prosieguo delle campionature nella piattaforma esterna. piattaforma esterna della piattaforma esterna si ha una buona definizione su base ecografica mentre della sedimentazione si hanno solo dati preliminari che documentano la presenza di sabbie fini fangose a lamellibranchi, foraminiferi ed echinidi irregolari. essa è individuabile esternamente alla paleo-riva dei –55 m, fino al bordo deposizionale della piattaforma posto a circa -115÷125 metri. l’ampiezza della piattaforma esterna, che costituisce l’infrastruttura per i fondali ricoperti dalle litofacies distali, è nettamente subordinata rispetto agli altri ambienti perché il livello eustatico di low-stand dei 1920 ky e i precedenti low-stand intercettavano il prisma deposizionale in prossimità della transizione alla parte profonda del bacino di cagliari; i sedimenti venivano pertanto deposti in condizioni poco stabili e in tempi brevi subivano processi di trasporto, granulare e di massa, verso il bacino. 7. discussione 7.1 ipotesi genetiche delle depressioni e del banco principale a posidonie la genesi delle depressioni e del banco principale a posidonie è decisiva per la comprensione del funzionamento sedimentario dell’intera piattaforma attuale. nella interpretazione di segre (1964) l’origine delle depressioni veniva attribuita alla erosione di valli fluviali durante la fase eustatica di low stand “wurmiana” (mis 4-2). riferendosi all’attuale funzionamento sedimentario della piattaforma, l’accrescimento del banco bioclastico a posidonie della piattaforma intermedia avrebbe sbarrato verso lo shoreface una depressione che costituirebbe una “laguna” fangosa silicoclastica e moderatamente carbonatica di mare temperato. questo implicherebbe, trascurando i fattori delle antecedenze di low stand, che l’alimentazione terrigena alla transizione shoreface-piattaforma intermedia non sia stata volumetricamente paragonabile all’accrescimento silicoclastico-carbonatico del banco verso l’alto, cioè abbia prevalso l’aumento di spazio disponibile (eustatic accomodation sensu posamentier et al., 1988) rispetto all’input terrigeno in shore face. una miglior ricostruzione deriva dall’interpretazione sequenziale delle registrazioni sub-bottom profiler (fig. 10) che evidenzia una genesi controllata contemporaneamente dai due fattori. si deduce che l’erosione di low stand, verificatosi lungo valli fluviali a est e a ovest di capo s. elia, abbia isolato delle colline; in fase di innalzamento eustatico le valli fluviali divenivano sede di lagune estuarine, mentre sulle colline si sono depposte sequenze sabbiose terrigene di shore-shoreface seguite, con l’annegamento, dall’instaurarsi del banco bioclastico a posidonie. col proseguire dell’innalzamento eustatico olocenico (maximum flooding), la depressione si sarebbe accentuata sia per la capacità del banco a posidonie di crescere verso l’alto, sia per il verificarsi di un deficit volumetrico di sedimenti nelle paleo-valli fluviali, derivato dalla retrogradazione dell’input terrigeno e dall’aumento dello spazio disponibile per l’innalzamento eustatico. pertanto i più recenti fattori di controllo di questa parte di piattaforma sarebbero individuabili nella presenza di paleo-morfologie del mis 2, nell’input terrigeno e nella produttività bioclastica. tali fattori hanno avuto entità paragonabili con una debole prevalenza della produttività carbonatica in fase di high stand (fig. 10). 7.2 definizione ed evoluzione della piattaforma nel quaternario il carattere essenzialmente bioclastico di gran parte della sedimentazione nell’intera piattaforma è chiaramente riferibile all’odierno contesto eustatico di high stand e alle condizioni di controllo della temperatura, salinità e limpidezza delle acque che permette condizioni di vita ottimali alle biocenosi a posidonie, ad alghe rosse, a molluschi e diverse altre. una tale pro218 l. lecca et al. duttività è comparabile ad altre aree del mediterraneo centrale e occidentale dove sono state descritte sedimentazioni carbonatiche come a ovest della sicilia e a est della tunisia (burollet, 1981; colantoni et al., 1993) e nelle isole baleari (mateu, 1989; fornos et al., 1991; fornos & ahr, 1997), ma nel golfo di cagliari si evidenzia una piattaforma articolata in ben diversificati ambienti. l’attuale morfologia del fondo marino caratterizza questa piattaforma e ne controlla i processi biologici, di trasporto e di deposizione. la presenza di aree depresse, attribuibili a paleo ambienti fluviali e costieri transizionali, contribuisce a confinare il terrigeno in piattaforma interna, mentre una fascia in rilievo distante dagli apporti terrigeni, in media piattaforma, costituisce un’areale ottimale per l’ecosistema a posidonia e, a maggiori profondità, per quelli algali, a lamellibranchi, echinidi e foraminiferi. il terrigeno prevale nello shoreface mentre nel resto della piattaforma viene prodotto sedimento carbonatico che, in piattaforma intermedia, si unisce ai sedimenti relitti terrigeni dando luogo a facies miste. nonostante il chiaro riconoscimento dell’attuale fase carbonatica, questa piattaforma non può essere definita carbonatica in senso stretto, perché durante tutto il tempo in cui tale piattaforma si è trovata in condizioni di livello eustatico più basso dell’attuale, fino ai massimi low stand, si sono avvantaggiati sempre più gli ambienti subaerei e di shoreface a sedimentazione continentale e sabbiosa terrigena. quindi i sedimenti relitti rappresentano un input terrigeno che si è realizzato maggiormente durante le fasi eustatiche di falling, low stand e rising, mentre la produttività bioclastica durante quella di high stand. in tal senso si può attribuire a questa piattaforma la seguente evoluzione con alterno comportamento. durante il “tirreniano” (mis 5) la piattaforma di cagliari ha funzionato come piattaforma carbonatica, probabilmente maggiormente produttiva dell’attuale, come si deduce dalla presenza di faune calde (c arboni & l ecca, 1985; c arboni & l ecca, 1992). durante la regressione “würmiana” (mis 4-2) le facies terrigene hanno raggiunto almeno la linea della paleoriva dei –55÷60 m e nella fase di massimo low stand le valli fluviali hanno inciso anche la piattaforma esterna (lecca et al., 1988). in seguito, nel post-glaciale, la risalita del mare ha rimaneggiato il terrigeno continentale in depositi sabbiosi di trasgressione (ravinement surface e trasgressive systems tract) fino a raggiungere l’attuale stadio di high stand systems tract terrigeno-carbonatico. possibili comparazioni con piattaforme mioceniche la distribuzione delle facies e l’evoluzione di questa piattaforma costituisce un modello, oltre che per le piattaforme quaternarie della sardegna e del mediterraneo, anche per le sequenze del miocene della sardegna, dove piattaforme miste heterozoan, prevalentemente ad alghe rosse, si sono impostate in un contesto trasgressivo a controllo tettonico, nel miocene inferiore (cherchi et al., 2000), e in un contesto regressivo nel miocene superiore (spano & barca, 2002). l’elemento di maggior interesse appare il controllo sulla produttività carbonatica di mare temperato operato dalla risalita eustatica, associata a bassi valori della subsidenza, come avviene attualmente nel golfo di cagliari, oltre ad altri fattori ambientali non considerati in questo lavoro e noti in letteratura (pomar et al., 2004). dal punto di vista della organizzazione spaziale della sedimentazione durante le fasi di high stand, deve essere sottolineata la contemporaneità delle facies terrigene “trasgressive” dello shoreface, con quelle carbonatiche della media piattaforma e l’inclinazione dello shoreface verso il bacino; tale architettura deposizionale implica la non coincidenza dei limiti litostratigrafici con le isocrone, come già illustrato nei modelli di stratigrafia sequenziale (e. g. sarg, 1988). 8. conclusioni una nuova campionatura e nuovi dati ecografici hanno consentito di meglio documentare e interpretare la presenza di una sedimentazione carbonatica di mare temperato nella piattaforma del golfo di cagliari. sono stati individuati 8 gruppi di litofacies che testimoniano la presenza di altrettanti distinti ambienti deposizionali, di cui è stata presentata una prima zonazione cartografica. dove la sedimentazione non risente di una sensibile produzione bioclastica i dati hanno confermato i modelli di sedimentazione delle spiagge sottomarine terrigene. nelle aree a sedimentazione mista, la zonazione è risultata più complessa e controllata da fattori sia idrodinamico-batimetrici che biologici. tale piattaforma è sede di un sistema sedimentario complesso che si evidenzia con processi deposizionali controllati dalla paleo-morfologia, in particolare legata all’ultimo stazionamento basso del mis 2, dal trasporto terrigeno, dall’energia del moto ondoso e dalla produttività carbonatica organogena. l’attuale contesto risulta quello di uno shelf wave-dominated “attenuato”, a clima caldo mediterraneo, con scarsi apporti terrigeni e importante produttività carbonatica in piattaforma intermedia e sedimenti relitti a diversi livelli batimetrici. i risultati portano a non considerare questa piattaforma come una rampa silicoclastica distalmente gradata, come ci si potrebbe aspettare dalla posizione “pericontinentale” e dalla presenza di apporti terrigeni a spese di rocce cristalline. l’associazione di due ambienti speciali come la depressione interna e il banco della piattaforma intermedia, infatti, caratterizzano la piattaforma di cagliari e le fanno assumere aspetti fisiografici e sedimentologici di tipo piattaforma carbonatica di mare temperato, nonostante il terrigeno sia comunemente presente. la produttività carbonatica ha prevalso nell’attuale high stand e negli altri precedenti del pleistocene medio-superiore, mentre i sedimenti relitti testimoniano una sedimentazione terrigeno-silicoclastica che ha prevalso durante le fasi glacio-eustatiche di falling, low stand e rising in ambienti di shoreshoreface, transizionali e fluvio-alluvionali. ringraziamenti il rilievo dei profili ecografici e il lavoro di campionatura sono stati eseguiti grazie alla disponibilità e alle competenze del corpo forestale e di vigilanza ambientale della regione sardegna (resp. s.v.m. dott. stefano orrù, dir. s.t.i.r. dott. paolo floris), che ha messo a disposizione i mezzi e il personale a cui vanno i nostri più sentiti ringraziamenti, in particolare alla base 219i sedimenti terrigeno carbonatici ... logistica operativa navale di cagliari (isp. c. salvatore barabino, isp. c. angelo piga, ass. antonio pira, ass. gianni dedola, ass. bruno cara, ass. marco mentisci, ass. carlo degioannis e ass. paolo locci). si ringraziano i revisori per la lettura critica e i consigli per la correzione del manoscritto. lavoro realizzato nell’ambito dei progetti: università degli studi di cagliari (m.i.u.r., 60%): “evoluzione dei bacini neogenico-quaternari del blocco sardo-corso: analisi tettono-sedimentarie stratigrafiche, sedimentologiche, paleoclimatiche e confronti con altre aree” (responsabile l. lecca). gruppo nazionale difesa catastrofi idrogeologiche, (g.n.d.c.i.-c.n.r.): “prevenzione e previsione degli eventi franosi a grande rischio – interlinea difesa dei litorali – unità operativa sardegna” (responsabile s. de muro). bibliografia adey w.h. & macintyre i.g. 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(1986) geomorphology of submerged late quaternary shorelines on the south sardinian continenal shelf. journal of coastal research, si (1), 73–82. unesco (1977) marine ecosystem modelling in the mediterranean – report of the second unesco workshop on marine ecosystem modelling. unesco reports in marine sciences, 1-111. 221 ms. ricevuto l’1 giugno 2005 testo definitivo ricevuto il 19 ottobre 2005 ms. received: june 1, 2005 final text received: october 19, 2005. i sedimenti terrigeno carbonatici ... imp.d'orefice& le eolianiti dell’isola d’elba: i depositi del promontorio del m. calamita e del golfo di viticcio maurizio d’orefice, roberto graciotti & flavio capitanio apat – servizio geologico d’italia/dipartimento difesa del suolo – via curtatone, 3 00185 roma. (e-mail: maurizio.dorefice@apat.it, roberto.graciotti@apat.it, flavio.capitanio@apat.it) riassunto: m. d’orefice et al., le eolianiti dell’isola d’elba: i depositi del promontorio del m. calamita e del golfo di viticcio. (it issn 0394-3356, 2007). nel presente lavoro vengono descritti alcuni depositi eolici affioranti nel tratto di costa occidentale del promontorio del m. calamita (settore sud-orientale dell’isola d’elba) e nel golfo di viticcio (settore centro-settentrionale dell’isola). i depositi eolici poggiano in discordanza sulle antiche coste rocciose modellate nel substrato, rinvenendosi finanche all’interno delle preesistenti valli fluviali, a volte oltre i 100 m di quota s.l.m. le eolianiti sono costituite prevalentemente da sabbie medio-grossolane ed in misura minore da ghiaie minute. la tessitura è openwork; tuttavia la maggior parte dei vuoti intergranulari è riempita da due generazioni di cemento carbonatico, che in alcuni casi rendono la tessitura cemento-sostenuta. al loro interno, le eolianiti sono caratterizzate da evidenti strutture sedimentarie, che consistono essenzialmente in stratificazione incrociata a grande scala, di tipo piana-tabulare. in essa prevalgono i set di strati frontali ad alto angolo, che hanno una forma tangenziale ed un’immersione generalmente verso terra. i singoli set di strati, interessati internamente da numerose superfici di riattivazione, sono troncati da superfici d’erosione, a basso angolo, immergenti verso mare. i depositi eolici, inoltre, sono contraddistinti da strutture sedimentarie secondarie, rappresentate da concrezioni intrasedimentarie verticali e sub-orizzontali. frequentemente i depositi eolici sono intercalati con paleosuoli rubefatti e con brecce di versante. l’analisi petrografica ha consentito di classificare le eolianiti come quarzo-areniti bioclastiche. esse, infatti, annoverano tra i costituenti principali bioclasti carbonatici, clasti silicatici e inclusi litici. i bioclasti derivano da frammenti di gusci di lamellibranchi, gasteropodi, echinodermi, briozoi, alghe rosse nodulari e foraminiferi bentonici. i clasti silicatici consistono principalmente in granuli di quarzo e feldspati: l’analisi morfometrica in due dimensioni dei granuli di quarzo suggerisce un certo grado di uniformità tra tutti gli affioramenti studiati, soprattutto per quanto riguarda i parametri di sfericità e d’arrotondamento. gli inclusi litici sono costituiti prevalentemente da frammenti di quarzo-areniti, con subordinate quantità di graniti l.s. e quarziti. i rapporti quantitativi dei litici sono pressoché costanti da un affioramento all’altro e non trovano corrispondenza nella litologia dei rispettivi bacini idrografici di appartenenza. la continuazione dei depositi eolici per diversi metri al di sotto del livello del mare attuale e la loro erosione ad opera dell’odierna dinamica marina, stanno a dimostrare che essi si sono formati nel corso di una fase di basso stazionamento del livello marino. durante questo intervallo di tempo, emergeva progressivamente dal mare un fondo sabbioso, che ha agito come zona d’alimentazione per questi depositi. i risultati delle datazioni con il radiocarbonio sui paleosuoli intercalati ai depositi eolici ed i dati cronologici sui reperti archeologici in essi contenuti, riportati in letteratura, permettono di attribuire le eolianiti in esame ai due stadi freddi dell’ultimo glaciale (stadio isotopico 4 e 2). la loro età è quindi ascrivibile al pleistocene superiore. abstract: m. d’orefice et al., the elba island eolianites: the deposits of the mt. calamita promontory and the viticcio gulf. (it issn 0394-3356, 2007). this paper is focused on some deposits of aeolian origin outcropping in the western coast of the mt. calamita promontory (southeastern sector of the elba island) and in the viticcio gulf (centralnorthern sector of the elba island). the aeolian deposits lie unconformably on the ancient, modeled rocky coasts of the substrate, and also occur inside the pre-existing river valleys, sometimes as far as 100 m a.s.l. the aeolianites are built up mainly by coarse to medium-sized sands and to a lesser extent by fine gravel. they have an open-work fabric; nevertheless, most of intergranular pores are filled by two generations of carbonatic cements, which can make the rock cementsupported. inside the aeolianites, characteristic sedimentary structures are clearly recognizable: they consist essentially in a tabular-planar cross-stratification. high angle foresets dipping landward and tangent to the base level are prevailing. each set is affected internally by several reactivation surfaces, and is truncated by low angle erosional surfaces dipping seaward. the aeolian deposits are also characterized by second-order sedimentary structures, which consist in vertical and sub-horizontal intra-sedimentary calcite-cemented concretions. along the coastline, particularly on the flat coasts, the upper surface of the aeolianites shows peculiar erosional micro-forms, consisting mainly in vertical tubules. also erosional macro-forms are present, such as kamenitza and rock pools. frequently, the aeolian deposits are interbedded with rubefied paleosols and with slope breccias, built up by polygenetic and heterometric angular clasts. petrographical analysis allowed us to classify the eolianites as bioclastic quartz-sandstones. in fact, their main components are carbonate bioclasts, silicate clasts, and lithic fragments. bioclasts derive from shell fragments of lamellibranchs, gastropods, echinoderms, briozoans, nodular red algae, and benthonic foraminifera. these latter mostly account for species belonging to a temperate to warm, intertidal marine paleoenvironment. silicate clasts consist mainly in quartz and feldspar grains, with minor amounts of micas, spinel, hematite, and clinopyroxene. the two-dimension morphometrical analysis performed on quartz grains suggests a certain degree of uniformity among the studied occurrences, in particular with the sphericity and roundness parameters. lithic fragments mostly count quartz-sandstones, along with minor amounts of granitic l.s. and quartzitic rocks. the quantitative ratios of lithics are nearly constant from an outcrop to another, without any correspondence with the lithology of their respective hydrographical basin. dipping of the aeolian deposits under the current sea level, together with their erosion by the present marine dynamics, demonstrate that aeolianites originated during a low standing phase of the sea level. during this time span, a sandy bottom progressively emerged from the sea and acted as a feeding area for these deposits. results of the radiocarbon age measurements performed on some palaeosoils interbedded between the aeolian deposits, along with chronological data on archaeological materials found inside these palaeosoils, as reported in literature, allow us to assign the studied aeolianites to the two cold stages of the last glacial (isotope stage 4 and 2). thus, the age of these deposits can be attributed to the upper pleistocene. parole chiave: depositi eolici, quarzo-areniti bioclastiche, strutture sedimentarie, pleistocene superiore, isola d’elba italia. keywords: aeolian deposits, bioclastic quartz-sandstones, sedimentary structures, upper pleistocene, elba island italy. il quaternario italian journal of quaternary sciences 20(1), 2007 21-44 22 m. d’orefice, r. graciotti & f. capitanio 1. introduzione durante il rilevamento geomorfologico delle isole dell’arcipelago toscano1, sono stati approfonditi alcuni aspetti legati alla geomorfologia ed alla geologia del quaternario di queste isole. in questo ambito, una particolare attenzione è stata rivolta ai depositi eolici, costituiti da areniti quaternarie con stratificazione incrociata, affioranti in più punti della fascia costiera dell’isola d’elba, testimonianze di depositi un tempo ben più estesi lungo le coste elbane (fig. 1). in particolare, come già segnalato da mazzanti (1983), essi si rinvengono tra cala mandriola e cala cancherelli, a viticcio, a scaglieri, nel golfo della biodola, lungo i due versanti del promontorio di capo stella, tra la punta di zuccale e la cala dell’innamorata, in alcune valli ad est di capoliveri e a cavo. a questi depositi, talvolta indicati con il nome di "panchina", è stata attribuita inizialmente un’origine marina (lotti, 1910) e successivamente un’origine eolica (barberi et al., 1969). tuttavia, il termine "panchina" può generare confusione: infatti, esso è stato utilizzato in passato per indicare areniti antiche e recenti, diffuse lungo le coste italiane e studiate con maggiore dettaglio nel litorale tosco-laziale, dove sono state ritenute in alcuni casi di origine marina (a partire dal gioli, 1894) e in altri eolica (a partire dal merciai, 1926). nel presente lavoro vengono illustrati e comparati tra loro i depositi eolici situati lungo la costa occidentale del promontorio del m. calamita (elba sud-orientale) e nel golfo di viticcio (elba centro-settentrionale). questi affioramenti sono stati selezionati sulla base dei seguenti criteri: i) in essi sono conservate le migliori esposizioni di strutture sedimentarie a grande scala; ii) essi appartengono ad aree ubicate in settori opposti dell’isola (promontorio del calamita e golfo di viticcio), contraddistinti da un contesto geomorfologico e litologico differente; iii) il settore del m. calamita studiato comprende tre località contigue (barabarca, stecchi e mad.na delle grazie), relativamente uniformi dal punto di vista geologico e geomorfologico, che consentono di valutare l’eventuale contributo di fattori morfologici locali. per la loro peculiarità e completezza di esposizione, quindi, le areniti esaminate consentono d’incrementare le conoscenze finora disponibili su questo litotipo. il presente lavoro si propone di descrivere, oltre ad alcuni aspetti morfologici, le maggiori strutture sedimentarie interne, nonché le principali caratteristiche mineralogiche e petrografiche delle eolianiti, al fine di contribuire a chiarire la loro origine ed alcune delle vicende evolutive che hanno interessato l’isola d’elba nel tardo-quaternario. 2. inquadramento geologico e petrografico la geologia dell’isola d’elba è molto articolata per la presenza, in uno spazio relativamente ristretto (circa 224 km2), di una notevole varietà di rocce ignee, metamorfiche e sedimentarie caratterizzate da un complesso assetto tettonico, conseguito nel corso di diverse tappe evolutive. in sintesi, l’evoluzione tettonica dell’isola d’elba ha avuto inizio con l’orogenesi varisica, che ha interessato le unità più profonde dell’edificio strutturale elbano ed in particolare il complesso metamorfico di m. calamita (garfagnoli et al., 2005) e l’unità di ortano (pandeli & puxeddu, 1990). nel corso della chiusura dell’oceano ligurepiemontese, verificatasi tra il cretacico superiore e l’eocene, è avvenuta la deformazione delle unità liguri e liguri-piemontesi. la successiva fase collisionale, che ha interessato questo settore dell’appennino settentrionale tra l’eocene superiore-oligocene ed il miocene inferiore, ha determinato la deformazione e l’impilamento delle unità tettoniche (interne) liguri e liguri-piemontesi sulle unità (esterne) toscane. la fase collisionale è stata seguita, probabilmente a partire dal miocene inferiore-medio, da una tettonica estensionale che ha causato l’apertura del bacino tirrenico e la risalita prima del plutone granodioritico del m. capanne (5,8-6,8 ma: metodo rb/sr, jateau et al., 1984; 6,7-6,9 ma: metodo rb/sr, ferrara & tonarini, 1985; 1993) ed in seguito del più piccolo plutone monzogranitico di la serra-porto azzurro (4,9-5,4 ma: metodo rb/sr, saupè et al., 1982; 5,9 ma: metodo ar40/ar39, maineri et al., 2003). la messa in posto dei corpi intrusivi ha determinato il termometamorfismo delle rocce incassanti, il sollevamento dell’area e lo scivolamento gravitativo dell’intero impilamento di falde (trevisan, 1950). questo meccanismo di scivolamento gravitativo ha portato alla traslazione verso est ed alla sovrapposizione anomala delle unità tettoniche formatesi nella fase collisionale: si è così delineata una struttura a scaglie tettoniche embricate e ripetute, separate da superfici di scorrimento sub-orizzontali. le ultime fasi di risalita del plutone di la serra-porto azzurro possono, inoltre, aver ulteriormente deformato le precedenti strutture del m. calamita e prodotto la blanda mega-antiforme del promontorio omonimo (garfagnoli et al., 2005). l’intero edificio strutturale elbano è stato, infine, disarticolato da una fase tettonica distensiva, di probabile età miocene superiore-pliocene inferiore, che ha dato luogo a faglie normali ad alto angolo ad andamento prevalente n-s (barberi et al., 1969; bortolotti et al., 2001) e ne-so e no-se (garfagnoli et al., 2005). promontorio del m. calamita (fig. 1a). le varie unità tettoniche che caratterizzano la parte centroorientale dell’isola d’elba furono per la prima volta suddivise da trevisan (1950) in cinque “complessi”. questo schema tettonico, ripreso e lievemente modificato da barberi et al. (1967a; 1969), è stato successivamente reinterpretato, ridenominato ed integrato da bortolotti et al. (2001). questi ultimi autori, in occasione del nuovo rilevamento geologico 1:10.000 dell’elba centroorientale, hanno infatti individuato nove principali unità tettoniche, di cui tre affioranti nell’area del m. calamita, 1 il rilevamento è stato effettuato nell’ambito della convenzione tra il servizio geologico nazionale, ora apat servizio geologico d’italia/dipartimento difesa del suolo, e l’università degli studi di roma tre, dipartimento di scienze geologiche. che verranno sinteticamente descritte di seguito a partire da quella più profonda. 1) “unità di porto azzurro” (corrispondente al “complesso i” di trevisan, 1950). e’ costituita da rocce polimetamorfiche, di almeno 800 m di spessore apparente, che formano la maggior parte del promontorio del m. calamita. esse vengono comunemente considerate il basamento metamorfico dell’isola d’elba. l’unità comprende una successione paleozoica di probabile età pre-carbonifera, denominata da garfagnoli et al. (2005) “complesso metamorfico di monte calamita”. le rocce di questa successione più abbondanti in affioramento sono scisti quarzoso-muscoviti23le eolianiti dell’isola d’elba ... co–biotitici. essi contengono porfiroblasti di andalusite, plagioclasio e più raramente granato. il complesso metamorfico di monte calamita è sormontato, in discordanza stratigrafica, da una copertura costituita da meta-sedimenti silicoclastici triassici (quarziti di barabarca) e da successioni carbonatiche del ?triassico superiore-?hettangiano (formazioni di tocchi e di calanchiole). le quarziti di barabarca hanno uno spessore massimo apparente di circa 50 m. esse contengono livelli fillosilicatici, filladi “macchiettate” (bonatti & marinelli, 1951) e “microanageniti” (barberi et al., 1967b). nell’insieme, questi tipi litologici sono comunemente riferiti al verrucano. la formazione di fig. 1 – rilievo ombreggiato dell’isola d’elba, ricavato dal modello digitale del terreno dell’igm con risoluzione di 20 m. sono indicati i toponimi riportati nel testo (nei riquadri le località di studio). a) settore del promontorio del m. calamita. b) settore del golfo di viticcio. shaded relief of the elba island, obtained from the 20 meter-resolution digital elevation model of igm. toponyms reported in the text are indicated (study areas are framed). a) mt. calamita sector. b) viticco gulf sector. 24 tocchi ha uno spessore massimo apparente di circa 150 m. le rocce che la costituiscono sono state interpretate come metadoloareniti con letti di calcescisti, talora fortemente tettonizzate (garfagnoli et al., 2005). i litotipi ascritti alla formazione di calanchiole non affiorano nelle aree oggetto del presente studio. nell’area di porto azzurro e nel settore orientale del promontorio del m. calamita, il complesso metamorfico è attraversato da numerosi filoni aplitici e subordinatamente granitico-granodioritici, connessi al plutone di la serra-porto azzurro (marinelli, 1959). 2) “unità ofiolitica” (“complesso iv” di trevisan, 1950). affiora solo nella più occidentale delle due isole gemini ed è rappresentata da serpentiniti e gabbri del giurassico superiore–cretacico inferiore. questa unità non è quindi compresa nelle aree esaminate nel presente lavoro. 3) “unità del flysch cretacico” (parte superiore del “complesso v” di trevisan, 1950). si estende tra la spiaggia delle calanchiole ed il centro abitato di capoliveri; inoltre, un piccolo affioramento è costituito dallo scoglio corbella. essa è separata dalla sottostante unità di porto azzurro da un orizzonte cataclastico decametrico, connesso alla faglia estensionale a basso angolo dello zuccale (keller & pialli, 1990; pertusati et al., 1993; daniel & jolivet, 1995). l’unità è rappresentata da una sequenza di terreni del cretacico superiore in facies di flysch. in particolare, si tratta di argille passanti verso l’alto ad arenarie e conglomerati torbiditici (arenarie di ghiaieto) e successivamente alternanze di marne, calcari marnosi e arenarie (formazione di marina di campo). questi litotipi sono interessati da frequenti, e localmente spesse, intrusioni filoniane e di ammassi granodioritici. numerosi studi mineralogici e petrografici si sono succeduti negli anni riguardo queste rocce: i loro risultati sono riportati in forma sinottica nella tab. 1a. golfo di viticcio (fig. 1b). il piccolo centro abitato di viticcio si affaccia sull’omonimo golfo, il quale è compreso tra il promontorio del m. enfola a nord ed il promontorio di penisola a sud. il substrato dell’area del golfo di viticcio comprende due sole tipologie litologiche, le cui caratteristiche sono riassunte nella tab. 1b. barberi et al. (1967a; 1969) evidenziano, nel settore in esame, la presenza di rocce del cretacico superiore in facies di flysch: esse molto probabilmente corrispondono alla formazione di marina di campo, che costituisce l’estrema parte superiore del “complesso v” di t revisan (1950), ovvero la parte superiore dell’“unità del flysch cretacico” di bortolotti et al. (2001). questa successione flyschoide, è descritta in letteratura in modo diverso da vari autori. aiello et al. (1977) hanno distinto tre facies in cui il contenuto percentuale in pelite aumenta verso l’alto. all’interno della stessa formazione, invece, bortolotti et al. (2001) hanno distinto quattro litotipi: 1) arenarie quarzoso-feldspatiche senza cemento carbonatico; 2) arenarie quarzoso-feldspatiche con cemento carbonatico; 3) calcareniti e marne; 4) argilliti. nel settore di viticcio, la formazione di marina di campo risulta frequentemente interessata da estese intrusioni di porfidi a composizione prevalentemente granitico-granodioritica, in forma di espandimenti, ammassi irregolari e filoni. dal punto di vista petrografico, i porfidi sono suddivisibili in due unità (marinelli, 1955; dini et al., 2002): 1) i “porfidi di portoferraio”, i quali affiorano in tutta l’elba centro–settentrionale, dove formano diversi strati laccolitici spessi fino a 700 m e numerosi dicchi. essi hanno composizione prevalentemente granodioritica, localmente sienogranitica; 2) i “porfidi di san martino”, i quali sono localizzati nei settori settentrionale e meridionale del golfo di viticcio, dove formano tre strati laccolitici spessi fino a 400 m e alcuni dicchi. essi hanno composizione granodioritica. 3. inquadramento geomorfologico l’elba si erge da una piattaforma continentale, che si estende dal litorale toscano sino al canale di corsica (fig. 1). la relativa regolarità del fondale marino, appartenente all’area di piattaforma circostante l’elba, è interrotta a nord e a sud dalle depressioni che si immettono rispettivamente nel bacino marino ubicato tra capraia ed il continente ed in quello situato tra montecristo ed il giglio, e ad ovest dalla dorsale sottomarina elba-pianosa (wezel, 1982), allungata in direzione n-s parallelamente al bacino corso. l’assetto e l’evoluzione geomorfologica dell’isola d’elba sono poco noti, anche a causa della mancanza in affioramento di sedimenti marini neogenici e quaternari e della scarsità di depositi continentali quaternari; questi ultimi, infatti, si rinvengono in areali piuttosto ristretti e sono principalmente costituiti da depositi alluvionali, di spiaggia, eolici, di versante e da coltri eluviocolluviali. ad uno sguardo d’insieme, il territorio elbano si presenta fortemente accidentato per la contiguità di rilievi di varia altezza e conformazione morfologica. l’elevata acclività dei versanti elbani è a volte interrotta da piccole superfici sub-orizzontali, distribuite a varie quote, le quali hanno suscitato l’interesse di studiosi come desio (1922) e centamore et al. (1988). in particolare, gli autori di quest’ultimo lavoro riconoscono, in quasi tutta l’isola, almeno tre ordini di superfici di spianamento relitte (rispettivamente 90-120 m, 45-75 m e 15-20 m s.l.m.) ed ipotizzano, anche se in assenza di precisi riferimenti crono-biostratigrafici, il loro collegamento con i livelli marini pleistocenici. i rilievi sono spesso delimitati verso mare da ripide falesie, e nell’entroterra sono solcati da incisioni vallive che terminano in anguste insenature o piccole baie marine. solo una modesta porzione del territorio elbano è contraddistinta da esigue piane alluvionali e costiere. rühl (1912) e poi barberi et al. (1969) hanno interpretato le insenature marine, presenti lungo le coste frastagliate in corrispondenza delle valli fluviali, come forme di sommersione, dovute all’ultima risalita eustatica del livello marino. oltre alla risalita eustatica, barberi et al. (1969), in conseguenza della totale assenza in affioramento di depositi marini neogenici e quaternari, ipotizzano una generale subsidenza dell’isola, che avrebbe coinvolto questi depositi in un lento abbassamento a partire dal pliocene. depositi di entrambe le età affiorano, invece, nella vicina isola di pianosa (foresi et al., 2000; graciotti et al., 2002-2003) e sono stati attraversati da due pozzi, mimosa 1 e martina 1, eseguiti dall’agip negli anni ’70, sulla dorsale sommersa m. d’orefice, r. graciotti & f. capitanio 25 tab. 1 – sinottica delle litologie e delle paragenesi del substrato delle aree in esame. lithology and parageneses of the substrate of the studied areas. formazione o unità intrusioni terziarie litotipi da graniti a granodioriti in filoni, ammassi ed espandimenti apliti in filoni strutture e tessiture porfirica; (micro)porfirica; pdf da granulare a granofirica pdf trachitica costituenti fondamentali fenoxx: kf, qtz, bt, pl; fenoxx: qtz, kf, pl, ms; pdf: qtz, pl, kf, bt pdf: (?) costituenti subordinati tur tur costituenti occasionali ap, zrn, ttn, aln, mnz, thorite mnz, xenotimo, nb-ta-ossidi fasi “autometamorfiche”: sericite, chl, cal, py, argille referenze porfidi (1; 2; 9) “euriti” (1) apliti (9) a) monte calamita formazione o unità “scisti del calamita” intrusioni terziarie litotipi micascisti e filladi da graniti a granodioriti apliti in filoni in piccoli ammassi e filoni strutture e tessiture strati quarzosi granoe porfiroblastici; porfirica; strati micacei lepidoe porfiroblastici pdf da granofirica a scistosa (micro)porfirica costituenti qtz, ms, bt, chl fenoxx: qtz; fenoxx: qtz; fondamentali pdf: pl, kf, qtz, bt pdf: pl, kf, qtz, bt costituenti subordinati and, pl, sericite, crd, kf ap, zrn, tur, crd tur, and, crd, ms costituenti occasionali tur, ap, zrn, ttn, rt, mag, hem, py and, py grt, ap, zrn scisti quarzoso-micacei (1) porfiriti (2) apliti (3) referenze scisti quarzoso-muscovitico-biotitici (3) porfidi (6) scisti (quarzoso-)muscovitico-biotitici (5) micascisti e filladi (quarzitici) (10) formazione o unità prodotti termometamorfici litotipi anfiboliti in lenti negli scisti cornubianiti in piccoli ammassi skarn in piccoli ammassi (c. pianuccio remaiolo) (capoliveri m. calamita) (c. calamita – sassi neri) strutture e tessiture da granolepidoa nematoblastica granolepidoblastica (?) granolepidoblastica costituenti fondamentali ortoam, pl pl, cpx. grt hbl, pl, kf costituenti subordinati qtz, ms, bt, hbl, ap, zrn, ttn, tur ttn, ap, cal ortoam, grt, cpx, ep, mag, py costituenti occasionali ap, ttn, ilm referenze anfiboliti (5; 10) cornubianiti (5) skarn (1; 10) formazione o unità quarziti di barabarca litotipi quarziti metaconglomerati strutture e tessiture da granoa lepidoblastica (?) costituenti fondamentali qtz clasti: qtz; fillosilicati cemento: qtz, miche costituenti subordinati and costituenti occasionali ap, tur, hem referenze quarziti di barabarca (5; 10) “microanageniti” (5) formazione o unità fm marina di campo litotipi areniti calcari scisti strutture e tessiture (?) (?) (?) costituenti fondamentali clasti: qtz, kf, pl, bt, ms cal argille cemento: fillosilicati, carbonati costituenti subordinati costituenti occasionali femici (?) referenze flysch (4) fm marina di campo (7; 8) formazione o unità fm tocchi fm calanchiole litotipi calcari dolomitici; filladi marmi e dolomie cristalline calcescisti strutture e tessiture da nematoa lepidoblastica diablastica da granoa xenoblastica costituenti fondamentali cal, dol qtz, fillosilicati cal, dol costituenti subordinati qtz, pl, bt, ortoam qtz, sericite costituenti occasionali anh, ccp, tur, mag, hem, py ortoam, phl, ap, hem referenze carbonati di capoliveri (3) marmi del calamita (5) fm tocchi (5; 10) fm calanchiole (10) b) golfo di viticcio referenze: 1 = bonatti e marinelli,1951; 2 = marinelli, 1955; 3 = marinelli, 1959; 4 = parea, 1964; 5 = barberi et alii, 1967b; 6 = barberi et alii, 1969; 7 = aiello et alii, 1977; 8 = bortolotti et alii, 2001a; 9 = dini et alii, 2002; 10 = garfagnoli et alii, 2005. le eolianiti dell’isola d’elba ... 26 elba-pianosa (cornamusini et al., 2002). inoltre, i vari profili sismici eseguiti in corrispondenza della piattaforma toscana evidenziano, nella loro parte superiore, la presenza di riflettori ben definiti in onlap sul substrato neogenico, riferibili a depositi quaternari marini (pascucci, 2002). alcune campagne oceanografiche, condotte dall’istituto di geologia marina del cnr di bologna (roveri & correggiari, 2004), hanno evidenziato le principali caratteristiche sedimentologiche dei depositi plio(?)-pleistocenici che costituiscono il tratto di piattaforma compreso tra l’elba e pianosa e quello circostante l’isola di capraia. i risultati di tali ricerche, basate su profili sismici e campionature, consentono di attribuire i sedimenti sopra citati a corpi deposizionali progradanti, costituiti da biocalcareniti e biocalciruditi ad alghe calcaree. promontorio del m. calamita. quest’area è caratterizzata da una peculiare forma tozza che si erge bruscamente dal mare, raggiungendo la quota massima di 412 m s.l.m. (fig. 1a). tale conformazione orografica è strettamente connessa al particolare assetto strutturale dell’area, contraddistinto dalla presenza della sopra citata mega-antiforme del m. calamita. più dell’80% di costa è alta, con ripide falesie, in gran parte attive, che raggiungono a volte altezze anche superiori ai cento metri, come nel tratto della costa dei gabbiani (estremo settore meridionale del promontorio). la linea di costa è molto frastagliata ed articolata a causa delle numerose piccole baie delimitate da dorsali rocciose che si protendono verso il mare. la parte sommitale del m. calamita mostra un allungamento in direzione e-o, corrispondente alla dorsale m. calamita–poggio fino. da essa si dipartono, con andamento radiale, numerose vallecole a “v”, che con un’elevata pendenza, dopo un percorso di circa 2 km, raggiungono direttamente il mare. le aste fluviali, in genere abbastanza rettilinee e di ordine gerarchico basso (non superiore al 4°) secondo la classificazione di strahler (1957), sottendono bacini imbriferi spesso stretti ed allungati. tali bacini hanno una pendenza media variabile tra i 10° e i 22° e un’estensione media di circa 0,8 km2; i bacini di maggior estensione sono esposti prevalentemente verso i quadranti occidentali. gli attuali thalweg fluviali sono incisi sia nel substrato metamorfico e sedimentario, sia nei depositi alluvionali recenti. piccoli conoidi alluvionali di origine mista, generati da dinamiche fluviali e di massa, sono ubicati allo sbocco dei corsi d’acqua nelle cale prospicienti la costa. golfo di viticcio. i rilievi a monte dell’abitato di viticcio presentano una minore elevazione rispetto a quelli del promontorio del m. calamita: infatti, i primi raggiungono la quota massima di 230 m s.l.m. (località le cime), in corrispondenza dello spartiacque tra i bacini idrografici drenanti verso il golfo di viticcio e il bacino del fosso acquaviva drenante verso nord (fig. 1b). in prossimità della linea di riva, questi rilievi danno luogo a coste alte, caratterizzate da falesie con altezza di circa 20 m, che si interrompono in coincidenza di alcune calette. esse ospitano piccole spiagge contraddistinte prevalentemente da depositi grossolani, costituiti da ghiaie e blocchi, con diametro massimo di circa 1 m; i singoli elementi presentano un elevato indice di arrotondamento e sono costituiti essenzialmente da litotipi flyschoidi e porfiroidi. le spiagge, tra cui quella del viticcio, sono ubicate allo sbocco di impluvi a regime temporaneo, che drenano modesti bacini idrografici. generalmente i bacini, orientati verso no, hanno una forma stretta ed allungata ed un basso ordine gerarchico (1° o 2°) in base alla classificazione di strahler (1957); solo quello più meridionale, di maggior estensione, è contraddistinto da una forma più o meno rettangolare e da un reticolo idrografico di 4° ordine gerarchico. 4. aspetti geomorfologici e strutture sedimentarie delle eolianiti 4.1. aspetti geomorfologici promontorio del m. calamita. nell’area del m. calamita, le eolianiti affiorano con continuità nella fascia costiera compresa tra la punta di barabarca e la spiaggia della madonna (fig. 1a), dove ammantano le antiche coste rocciose modellate nel substrato e solitamente danno origine a corpi sedimentari disposti all’incirca parallelamente alla linea di costa. questi depositi si rinvengono, inoltre, all’interno delle incisioni vallive, che sfociano in corrispondenza delle insenature marine di barabarca, di stecchi, di mad.na delle grazie, di peducelli, di morcone, di pareti e dell’innamorata. in tal caso, essi danno luogo a corpi di spessore più che decametrico, alloggiati all’interno dei fondovalle fluviali, che risalgono, a partire dalla costa, per distanze di diverse centinaia di metri (fig. 2a), superando anche i 100 m di quota s.l.m., come nel caso degli affioramenti della mad.na delle grazie. la loro incisione da parte del reticolo idrografico attuale, dà luogo a forre, al cui interno frequentemente si rinvengono accumuli da frana di crollo e/o ribaltamento. generalmente, la superficie erosiva, attraverso la quale i depositi in esame poggiano in discordanza sul substrato metamorfico e sedimentario, è identificabile all’interno delle incisioni vallive e in alcuni casi lungo il litorale, a causa dell’arretramento costiero indotto dall’erosione marina. tuttavia a questo fa eccezione l’affioramento della spiaggia della madonna, dove nella zona supratidale la superficie d’erosione non è visibile in quanto collocata al di sotto dell’attuale livello marino (fig. 2b). golfo di viticcio. le eolianiti affiorano in corrispondenza della parte medio-alta della falesia che, con un’altezza di circa 20 m, domina la spiaggia del viticcio (fig. 1b). esse costituiscono un corpo sedimentario di forma prismatica di circa 15 m di spessore massimo, il quale va progressivamente rastremandosi verso l’entroterra, risalendo il versante retrostante sino a circa 70 m di quota s.l.m. (fig. 3). il corpo sedimentario è limitato alla base da una superficie d’erosione, degradante verso mare con una pendenza di circa 20°, attraverso la quale poggia in discordanza sul substrato, rappresentato da porfidi granodioritici e granitici e dal flysch appartenente alla formazione di marina di campo. al tetto il litosoma è delimitato da una superficie m. d’orefice, r. graciotti & f. capitanio d’erosione corrispondente all’attuale superficie topografica. 4.2. caratteri macroscopici delle eolianiti le rocce del presente studio hanno un colore 2,5 y 5/4 (marrone giallastro). dal punto di vista granulometrico, esse sono costituite prevalentemente da sabbie a grana media e grossolana ed in misura molto minore da ghiaie minute (granuli di diametro tra 2 e 4 mm). in linea generale, la cementazione è elevata al punto tale da formare delle vere e proprie areniti ed in rari casi delle ruditi. il grado di cementazione è, comunque, variabile in funzione della granulometria dei grani. infatti, gli strati a granulometria più fine tendono ad essere maggiormente cementati rispetto a quelli a granulometria più grossolana. il diverso grado di cementazione viene enfatizzato dalla morfoselezione, che mette in evidenza un’alternanza di strati più e meno resistenti ai processi erosivi (fig. 2b). all’interno dei singoli strati non si riscontra una gradazione dei granuli; sono, invece, visibili inclusi litici di dimensioni millimetriche. macrofaune fossili sono quasi del tutto assenti ad eccezione di qualche frammento di bivalve marino (avente dimensioni non superiori a qualche centimetro) e rari gusci di gasteropodi terrestri. 4.3. principali strutture sedimentarie delle eolianiti nel loro insieme, le eolianiti sono caratterizzate internamente da strutture sedimentarie principali, che consistono essenzialmente in stratificazione incrociata a grande scala. uno dei migliori esempi di queste strutture sedimentarie è visibile nella sezione di origine antropica ubicata circa 200 m a nord della spiaggia della madonna, dove è osservabile in tre dimensioni la stratificazione sopra descritta (fig. 2c). infatti, la gran parte della sezione, ad eccezione dell’estrema porzione superiore, è contraddistinta da stratificazione incrociata di tipo piana-tabulare. prevalgono i set di strati frontali, i quali general27 fig. 2 – area di madonna delle grazie. a) affioramento di eolianiti nei pressi della chiesa della madonna delle grazie (a quota circa 30 m s.l.m.). set di strati immergenti contro monte con una pendenza di circa 20°; b) affioramento di eolianiti nei pressi della spiaggia della madonna; c) ricostruzione schematica delle strutture sedimentarie e delle superfici d’erosione dell’affioramento di eolianiti in b). la maggior parte della sezione è composta da un set di strati, ad alto angolo, di forma tangenziale immergenti verso terra (b). il set è delimitato da due superfici di erosione (s1 e s2), debolmente inclinate verso mare, ed è caratterizzato al suo interno da numerose superfici di riattivazione. sulla superficie superiore (s2) poggiano in discordanza detriti di versante clinostratificati (d), a cui segue in concordanza una sequenza eolica con stratificazione pianoparallela a basso angolo d’inclinazione (c). è interessante notare la prosecuzione del corpo sedimentario sia in direzione orizzontale (verso mare), sia in quella verticale (al di sotto dell’attuale battigia). the madonna delle grazie area. a) aeolianite outcrop near the church of madonna delle grazie (about 30 m a.s.l.). foresets dipping about 20° landward; b) aeolianite outcrop near the spiaggia della madonna; c) schematic reconstruction of sedimentary structures and erosion surfaces of the aeolianite outcrop of b). the cut is mostly built up by a high angle foresets dipping landward and tangent to the base (b). the set is bounded by two erosional surfaces (s1 and s2), slightly dipping seaward, and it contains several reactivation surfaces. stratified slope-waste deposits (d) lie unconformably on the upper erosion surface (s2). an aeolian sequence (c), with a low angle parallel stratification, lies conformably on slope-waste deposits. it is interesting to note the extension of the whole sedimentary body in both the horizontal (towards the sea) and the vertical (under the present waterline) directions. a) b) c) le eolianiti dell’isola d’elba ... mente hanno un’immersione verso terra ed assumono una forma tangenziale verso la base. i singoli strati sono spessi da 5 a 25 mm ed hanno, nella loro porzione più elevata, inclinazioni prevalentemente ad alto angolo variabili tra i 25° ed i 32°, ma che in alcuni casi possono raggiungere i 35°. i set di strati frontali sono di tipo composto in quanto contengono al loro interno delle superfici di discontinuità. i singoli set di strati sono troncati da superfici di erosione, inclinate di circa 10° 12° verso mare e contraddistinte da una evidente ondulazione. in particolare, nell’affioramento della spiaggia della madonna sono visibili due superfici di erosione che troncano verso l’alto due set di strati frontali, caratterizzati da giaciture differenti. infatti, il set più alto (b), delimitato al tetto dalla superficie superiore (s2), è spesso da circa 4,5 a 5,5 m ed è costituito da strati frontali con una direzione d’immersione variabile tra n60° e n80° ed inclinazione degli stessi fino a 35°. il set sottostante (a), delimitato al tetto dalla superficie inferiore (s1), è formato, invece, da strati con direzione d’immersione n40° e pendenza di circa 10°. al di sopra della superficie di erosione superiore (s2), poggiano in discordanza, depositi di versante (d) di circa 70-80 cm di spessore, costituiti da strati a geometria piano-parallela con basso angolo d’inclinazione, variabile tra 10° e 12°, e con un’immersione in genere verso mare (n220°). ai depositi di versante, segue, in concordanza, un’altra sequenza eolica (c) di circa 50 cm di spessore, caratterizzata da una stratificazione da piano-parallela a leggermente ondulata. quest’ultima è delimitata superiormente da una superficie d’erosione corrispondente all’attuale piano topografico. nell’area di viticcio, le eolianiti sono organizzate in strati prevalentemente piano-paralleli, debolmente inclinati verso mare. in diversi affioramenti, all’interno delle areniti si rinvengono strutture sedimentarie secondarie costituite da concrezioni intrasedimentarie sia sub-orizzontali e sia verticali (fig. 4). le prime, più frequenti, si presentano come corpi arenacei fortemente allungati, dalla forma più o meno cilindrica e con sezione trasversale circolare, ellittica o irregolare (diametro variabile tra 0,5 e 2 cm). questi elementi cilindrici, spesso tra loro coalescenti, sono inclinati verso mare di circa 10°. le seconde, più rare, sono costituite da corpi arenacei analoghi ai precedenti, dai quali si distinguono nettamente per essere allungati verticalmente, per una minore uniformità di cementazione e per le minori dimensioni. 4.4. paleosuoli e depositi di versante associati alle eolianiti alternati ai depositi arenacei si rinvengono, di solito, degli orizzonti prevalentemente sabbiosi di colore rosso, talora associati a detriti di versante costituiti da clasti poligenici con tessitura a supporto di matrice. in particolare, nel tratto di costa tra la punta di barabarca e la spiaggia di stecchi sono state individuate due sequenze eoliche, con intercalato un paleosuolo rubefatto (fig. 5a-b). 28 fig. 3 spiaggia del viticcio. depositi eolici poggianti sul substrato igneo e flyschoide attraverso una superficie d’erosione (linea bianca tratteggiata) inclinata di circa 20° verso mare. il corpo sedimentario, contraddistinto da una forma prismatica, va progressivamente rastremandosi verso terra. allo stato attuale, i depositi sono sottoposti ad uno scalzamento alla base da parte del mare, con conseguente innesco di fenomeni di crollo e ribaltamento. the spiaggia del viticcio. aeolian deposits lie on the igneous and flyschoid substrate by an erosion surface (dashed white line), which is almost 20° dipping seawards. the prismatic sedimentary body becomes progressively thinner landward. at present, these deposits are undergoing underwash by the seawaters: this is a triggering factor for rockfall and topple phenomena. fig. 4 tratto di costa tra punta di barabarca e stecchi. depositi eolici caratterizzati prevalentemente da tubuli suborizzontali e subordinatamente verticali. coastline between punta di barabarca and stecchi. aeolian deposits are characterized by tubules: they have mainly subhorizontal and in a lesser extent vertical elongation. m. d’orefice, r. graciotti & f. capitanio esso ha un colore 2,5 yr 4/6 (rosso), una geometria lenticolare ed è costituito da sabbie limose a volte debolmente argillose, con spessori che possono superare abbondantemente il metro. sia nella frazione fine sia in quella grossolana non si riscontra presenza di carbonato di calcio. le superfici esposte agli agenti atmosferici presentano grado di compattezza abbastanza elevato. la materia organica, in genere scarsa, è costituita da piccoli frammenti di carbone, che hanno fornito, nel caso della sezione di m.na delle grazie, un’età 14c di 48.000 ± 1.900 anni b.p. (cremaschi & trombino, 1998). questa datazione, seppure al limite del metodo, è in sostanziale accordo con un’altra effettuata dagli autori sopra citati su un analogo paleosuolo rinvenuto tra due sequenze eoliche affioranti presso cala cancherelli (elba settentrionale). i frammenti di carbone contenuti in questo paleosuolo, situato in un contesto stratigrafico e morfologico identico a quello di m.na delle grazie, hanno infatti fornito un’età radiometrica di 40.831 ± 1.373 anni b.p. nel medesimo paleosuolo sono stati inoltre rinvenuti, dagli stessi autori, manufatti musteriani. all’interno delle eolianiti e del paleosuolo si possono notare, a varie altezze, sottili lenti oppure livelli sub-orizzontali o debolmente inclinati di materiale detritico (d), costituito da elementi poligenici, eterometrici (dimensioni da millimetriche a decimetriche) e spigolosi, spesso fortemente cementati, legati a fasi erosive dei versanti soprastanti (fig. 5b). i corpi detritici in posizione stratigrafica inferiore sono quelli poggianti direttamente sul substrato e sottostanti ai depositi eolici, mentre quelli in posizione stratigrafica più elevata si sovrappongono direttamente alla sequenza eolica superiore. nell’affioramento della spiaggia della madonna, le lenti detritiche comprese nelle porzioni a stratificazione incrociata (b: vedi fig. 2c) delle eolianiti possono raggiungere uno spessore massimo di 40 cm ed una lunghezza di 5 m (fig. 6a); i clasti sono costituiti da frammenti di rocce metamorfiche nerastri e verdastri (prevalentemente micascisti, quarziti e calcari termometamorfosati), spesso ad elevato grado di alterazione. al di sopra dei depositi eolici (b), si rinvengono i sopraccitati livelli detritici a stratificazione piano-parallela (fig. 6b). in questo caso, però, i clasti non sono in contatto reciproco, ma sono a supporto della matrice sabbioso-ghiaiosa che costituisce le eolianiti. in questi livelli, le dimensioni dei clasti tendono ad aumentare procedendo verso l’alto, passando da alcuni millimetri di diametro a circa 10 cm. gli elementi di forma piatta di solito sono allungati secondo il loro asse maggiore ed alcuni presentano una leggera embricatura. 4.5. micro e macroforme di erosione superficiale e fenomenologie di dissesto lungo la fascia costiera, i depositi arenacei in esame, ed in particolare quelli tra stecchi e la spiaggia della madonna, sono interessati, sulla loro superficie superiore, da peculiari forme di erosione di varia tipologia. in analogia con quanto osservato da mazzanti & parea (1977) lungo il litorale livornese, tali forme sono disposte lungo distinte fasce fisiografiche parallele alla linea di riva e di ampiezza variabile in funzione dell’acclività della costa. esse sono distribuite fra il limite massimo raggiunto dai marosi di tempesta e la parte terminale degli affioramenti di eolianiti al di sotto del livello del mare. procedendo verso mare, a partire dal limite inferiore della zona completamente vegetata e considerando solo le forme di erosione subaeree, è possibile 29 fig. 5 paleosuoli e depositi di versante (d) alternati alle eolianiti. a) tratto di costa tra punta di barabarca e stecchi. paleosuolo rosso intercalato tra due corpi sedimentari di eolianiti. all’interno del paleosuolo si notano dei livelli sub-orizzontali formati da clasti, anche decimetrici, eterometrici e spigolosi, costituiti da detriti di versante (d); b) ricostruzione schematica della successione stratigrafica affiorante poco a nord di stecchi. si possono osservare due sequenze di natura eolica, con intercalato un paleosuolo rosso. la sequenza inferiore poggia su depositi di versante. paleosoils and slope debris (d) interbedded with the aeolianites. a) coast between punta di barabarca and stecchi. rubified paleosol interbedded between two aeolianite sedimentary bodies. inside the paleosol, some sub-horizontal levels are evident: they are slope debris (d) built up by angular and heterometric, up to dm-sized, clasts; b) schematic reconstruction of the stratigraphic succession outcropping just north of stecchi. two aeolian sequences with an interbedded red paleosol are recognizable. the lower sequence lies on slope deposits. a) b) le eolianiti dell’isola d’elba ... distinguere una zona supratidale e una zona intertidale. questa distinzione può essere agevolmente operata nei tratti di costa bassa, come appunto tra stecchi e la spiaggia della madonna. in sintesi, nella zona supratidale si riconosce una fascia superiore di colore chiaro, interessata da una elevata “spugnosità” conferita da “tubuli” verticali internamente vuoti, che si ergono dal suolo per circa 20 cm, a cui sono associate piccole vaschette di forma irregolare e con un diametro massimo dell’ordine del decimetro. queste sono svasate verso l’alto e spesso hanno il fondo colmato da suolo su cui attecchiscono essenze vegetali. questa fascia sfuma verso mare in una seconda più scura, caratterizzata da vaschette di corrosione a contorno irregolare per la coalescenza di più forme erosive. le vaschette, prive di un’orientazione preferenziale, hanno l’asse maggiore di lunghezza variabile da qualche decimetro ad alcuni metri. esse tendono, comunque, a regolarizzarsi con l’approssimarsi della fascia intertidale. i setti divisori tra le varie vaschette, spesso sottili e taglienti, sono cesellati da un insieme di vacuoli disposti “a nido d’ape” e con apertura generalmente orientata verso mare. nella zona intertidale, di estensione metrica e colore più scuro rispetto alla precedente poiché satura di acqua marina, le cavità assumono progressivamente una forma cilindrica e possono essere considerate delle vere e proprie marmitte di abrasione marina (fig. 7). esse sono in genere singole, hanno un diametro massimo di circa 1 m ed una profondità che può raggiungere i 40-50 cm. le pareti tendono ad essere aggettanti verso l’alto, mentre il fondo è piatto e privo di deposito. in corrispondenza della fascia costiera, tra stecchi e la spiaggia della madonna, è possibile osservare che le eolianiti sono interessate da due principali famiglie di fratture verticali, con direzione rispettivamente n50° e n140° e spaziatura di 30 fig. 6 diverse posizioni stratigrafiche dei detriti di versante (d). a) eolianite affiorante presso la spiaggia della madonna. lente detritica all’interno del set a stratificazione incrociata (porzione basale di b: vedi fig. 2c); b) stesso affioramento di a). detriti di versante stratificati, inclinati di 10-12° verso mare, poggianti in discordanza sul set a stratificazione incrociata (porzione sommitale di b) attraverso la superficie di erosione s2. different stratigraphic positions of slope debris (d). a) aeolianite outcropping near the spiaggia della madonna. a lens of debris inside the cross-stratified set (basal portion of b: see fig. 2c) is recognizable; b) same outcrop as a). stratified slope-waste deposits, 10-12° dipping seaward, lying unconformably on the cross-stratified set (upper portion of b) by the erosion surface s2. a) b) m. d’orefice, r. graciotti & f. capitanio alcuni metri. l’intersezione di queste due famiglie di fratture con le superfici di discontinuità sub-orizzontali legate alla stratificazione o alla presenza delle superfici di erosione, porta all’isolamento di prismi di una decina di m3 di volume, che a causa dell’erosione marina possono trovarsi, in prossimità della costa, in condizioni d’instabilità o addirittura essere coinvolti in crolli o ribaltamenti (fig. 8). 5. mineralogia e petrografia delle eolianiti 5.1. caratteri microscopici delle eolianiti i granuli che costituiscono i depositi eolici del presente studio possiedono una certa variabilità di dimensioni e forme, sia da un affioramento all’altro sia all’interno di uno stesso affioramento. ciò rende difficoltoso il confronto tra i diversi depositi, eseguito sulla base dei soli caratteri morfometrici dei granuli. tuttavia, nel presente lavoro è stata svolta un’indagine a scala microscopica finalizzata non solo ad identificare le specie mineralogiche e gli inclusi litici presenti in questi depositi, ma anche a verificare la possibilità di ottenere trend significativi a partire dalle misure morfometriche dei granuli, dalle quali possono scaturire delle informazioni utili alla correlazione tra i diversi affioramenti. a questo scopo, è stato eseguito un campionamento mirato sulla porzione granulometricamente più fine delle rocce in affioramento, in quanto: i) la frazione più fine è volumetricamente sempre predominante, anche nel caso di rocce costituite da alternanze con livelli a granulometria sabbioso-ghiaiosa; ii) solo il confronto tra campioni aventi granulometrie analoghe può fornire dati direttamente correlabili. la caratterizzazione mineralogico-petrografica delle eolianiti è stata eseguita su sezioni sottili di campioni prelevati negli affioramenti di barabarca, stecchi, mad.na delle grazie e viticcio. per ogni campione, sono state effettuate diverse sezioni sottili orientate parallelamente e perpendicolarmente rispetto alla stratificazione. in generale, i campioni analizzati presentano una composizione mineralogica abbastanza uniforme. essi sono formati da granuli di natura poligenica e presentano, tra i costituenti principali, bioclasti carbonatici, clasti prevalentemente silicatici e inclusi litici. anche alla scala microscopica, non è evidente alcuna gradazione degli elementi costitutivi della roccia, i quali hanno distribuzione spaziale non organizzata. il grado di selezionamento (sorting) risulta generalmente piuttosto variabile anche in campioni appartenenti allo 31 fig. 7 – marmitte d’abrasione marina modellate nelle eolianiti, affioranti nella zona intertidale superiore della spiaggia di stecchi. marine rock pools modeled into the aeolianites of the upper intertidal zone of the spiaggia di stecchi. fig. 8 fenomeni di crollo e ribaltamento nei depositi eolici tra punta di barabarca e stecchi, innescati dall’intensa azione erosiva da parte del mare. sono visibili i detriti di versante (d) tra substrato quarzitico ed eolianiti. rockfall and topple phenomena are triggered by the intense erosive marine dynamics in the aeolianite deposits outcropping between the punta di barabarca and stecchi. slope debris (d) between the quartzitic substrate and the aeolianites are also recognizable. le eolianiti dell’isola d’elba ... stesso affioramento: ad esempio, a m.na delle grazie i valori determinati per confronto con le carte di comparazione visiva variano tra 0,60 φ (“moderatamente ben selezionato”) e 1,50 φ (“poco selezionato”). la tessitura è generalmente open-work. tuttavia, la maggior parte dei vuoti intergranulari è riempita da cemento carbonatico, che in alcuni casi rende la tessitura cemento-sostenuta. 5.1.1. bioclasti (contributo di g. ventura) la componente organogena (fig. 9a-b) è costituita da frammenti di gusci di dimensioni sub-millimetriche, in genere ben arrotondati, spesso ricristallizzati, appartenenti a lamellibranchi, gasteropodi, echinodermi e briozoi, da frammenti di alghe rosse nodulari e da foraminiferi bentonici (tab. 2). per quanto concerne questi ultimi, sono stati riconosciuti elementi appartenenti alle famiglie cibicididae (barabarca, stecchi, viticcio), discorbidae (stecchi), elphididae (barabarca, stecchi, mad.na delle grazie, viticcio), miliolidae (barabarca, stecchi, mad.na delle grazie, viticcio), planorbulinidae (mad. na delle grazie), rotalidae (barabarca, mad.na delle grazie) e textularidae (stecchi). si segnala, infine, la presenza di un frammento di foraminifero planctonico (orbulina) in un campione di barabarca. la percentuale dei bioclasti è elevata, seppur variabile anche in uno stesso campione, e può raggiungere anche il 50 % del totale. 5.1.2. clasti prevalentemente silicatici le paragenesi mineralogiche relative alla componente silicoclastica delle areniti esaminate sono riportate nella tab. 3. il dettaglio delle caratteristiche delle sin32 frazione organica campioni barabarca stecchi m.na delle grazie viticcio echinidi (frammenti) x x x molluschi (frammenti) x briozoi (frammenti) x x crostacei (frammenti) x alghe corallinacee x x x x (frammenti) cibicididae lobatula lobatula lobatula lobatula (walker & jacob) discorbis globularis discorbidae (d’orbigny); rosalina bradyi (cushmann) elphididae elphidium elphidium elphidium advenum elphidium advenum (cushmann) (cushmann) adelosina quinqueloculina quinqueloculina seminulum quinqueloculina triloculina triloculina (linnaeus); miliolidae cicloforina massilina adelosina cicloforina triloculina cicloforina planorbulinidae planorbulina mediterranensis (cushmann) rotalidae x x textularidae textularia x orbulinidae orbulina tab. 2 classificazione e distribuzione della frazione organica nelle eolianiti del presente lavoro. classification and distribution of the organic fraction in the aeolianites of this work. f o r a m i n i f e r i tab. 3 sinottica delle paragenesi delle eolianiti del presente lavoro. parageneses of the aeolianites of this work. abbondanza viticcio barabarca stecchi m. delle relativa grazie costituenti qtz qtz qtz qtz fondamentali kf kf kf pl mica bruna kf pl cpx costituenti spl cpx cpx mica bianca subordinati mica bianca spl spl spl hem hem pl mica bruna hem grt mica bianca mica bruna mica bruna costituenti hem mica bianca pl occasionali cpx am grt am ap m. d’orefice, r. graciotti & f. capitanio gole specie mineralogiche riconosciute, invece, è illustrato nella tab. 4. tra i minerali silicatici, il quarzo è la specie mineralogica preponderante; la seconda specie mineralogica per abbondanza è il feldspato potassico; il plagioclasio è molto comune a viticcio e stecchi, risulta meno abbondante a barabarca ed è raro a mad. na delle grazie. l’abbondanza della mica bruna diminuisce da viticcio a barabarca fino a mad.na delle grazie e stecchi; invece, quella della mica bianca varia da apprezzabile (barabarca, mad.na delle grazie) a modesta (stecchi, viticcio). il clinopirosseno è un costituente occasionale a viticcio e subordinato negli altri affioramenti. lo spinello nero è generalmente un costituente subordinato. in tutti i campioni esaminati sono stati rinvenuti rari clasti micritici di natura carbonatica, bene arrotondati, dei quali non è possibile stabilire in modo univoco l’origine extrao intrabacinale. 5.1.3. inclusi litici: descrizione e classificazione nei campioni di areniti esaminati, sono presenti numerose e varie tipologie di inclusi. le loro caratteristiche principali sono illustrate nelle fig. 9b-e e riassunte nella tab. 5: quarzo policristallino, con tessitura isotropa, la cui origine è riconducibile a quarziti; quarzo e subordinate miche, con tessitura scistosa: si tratta di frammenti di quarzoscisti; aggregati costituiti da soli fillosilicati, a grana fine, e aggregati costituiti da fillosilicati, quarzo, plagioclasio e feldspato potassico, a grana media, con evidente tessitura scistosa: i loro protoliti sono micascisti; quarzo e subordinate miche, con tessitura isotropa e grana variabile da grossa a fine: sono frammenti di quarzo-areniti provenienti dal substrato flyschoide; aggregati di feldspato potassico, plagioclasio e clinopirosseno, con tessitura isotropa: si tratta di frammenti di rocce 33 tab. 4 dettaglio delle caratteristiche mineralogiche e petrografiche della componente silicoclastica delle eolianiti del presente lavoro. detail of mineralogical and petrographical features of the siliciclastic component of the aeolianites of this work. specie mineralogica caratteristiche ottiche quarzo subedrale, talora forma geminati semplici, talora ha estinzione ondulata e bordi in dissoluzione. include apatite, spinello nero, mica bruna e clinopirosseno (barabarca), plagioclasio (stecchi), clinopirosseno (viticcio). feldspato potassico subedrale, pertitico, spesso forma geminati semplici, talora ha patchy-zoning, talora è cribroso ed ha bordi in dissoluzione. possiede i caratteri ottici del sanidino (pseudouniassico negativo). mostra alterazione micaceo-argillosa, in alcuni casi cloritizzazione (barabarca), talora parziale sostituzione da parte di carbonato (viticcio). include quarzo, mica bruna e clinopirosseno (viticcio). plagioclasio da anedrale (viticcio) a subedrale, forma geminati polisintetici, ed è generalmente cribroso. ha alterazione micaceo-argillosa. include quarzo e mica bruna (viticcio). mica bruna pleocroica dal giallo bruno al bruno scuro, talora scheletriforme (barabarca, viticcio), talora ossidata, possiede uno zoning ottico compatibile con un aumento dal rapporto mg/fe verso il bordo dei cristalli. mica bianca debolmente pleocroica da incolore a giallo chiaro, spesso forma glomeruli (barabarca). talora è ossidata e in alcuni casi cloritizzata (mad.na delle grazie). clinopirosseno da anedrale a subedrale (stecchi), ha pleocroismo da incolore a giallo a verde corrispondente a termini diopsidico–augitici. talora forma geminati semplici, possiede uno zoning ottico compatibile con aumento dal rapporto fe/mg verso il bordo dei cristalli, talora mostra patchy-zoning, è cribroso (barabarca), e forma glomeruli. le alterazioni più diffuse sono la cloritizzazione, l’argillificazione e l’ossidazione. include mica bruna (barabarca). spinello nero da anedrale a euedrale anche nella stessa roccia (mad.na delle grazie, stecchi), talora è cribroso (barabarca) e con anse da rifusione (viticcio). spesso è ossidato. ematite da anedrale a subedrale (stecchi), contiene essoluzioni (viticcio). granato anedrale, giallo bruno caratteristico di termini ricchi in ferro. tab. 5 sinottica delle caratteristiche mineralogiche e petrografiche degli inclusi litici delle eolianiti del presente lavoro. mineralogical and petrographical features of the lithics included in the aeolianites of this work. paragenesi tessitura protoliti origine qtz isotropa quarziti x x x x qtz, miche scistosa quarzoscisti metamorfica x x x miche, qtz, kf, pl scistosa micascisti x x qtz, miche, kf(*), pl(*) isotropa areniti sedimentaria x x x x kf, pl, cpx isotropa granodioriti plutonica x x intergranulare qtz, kf, pl, cpx/miche(**) variolitica graniti l.s. ipoabissale x x x x porfiritica v it ic c io b a ra b a rc a s te c c h i m . d e lle g ra zi e (*) specie presenti solo a viticcio; (**) a viticcio è presente solo mica bruna, mentre nelle altre località è presente solo cpx. le eolianiti dell’isola d’elba ... fig. 9 caratteri microscopici delle eolianiti elbane. a) sezione subassiale di elphidium sp. (foraminifero bentonico) nelle areniti di viticcio (campione vi 8). nicol paralleli; b) bioclasti costituiti da alghe corallinacee (b) associati a frammenti ignei a feldspati con struttura porfirica e tessitura variolitica, di origine ipoabissale (i). si noti il basso grado di sorting della roccia. madonna delle grazie (campione mg 2). nicol paralleli; c) incluso igneo olocristallino inequigranulare (p), costituito da cristalli di quarzo e feldspati e macrocristalli di feldspati con incipiente seriticizzazione, di origine plutonica. esso è associato ad inclusi quarzo-arenitici (s), contenenti lamelle di mica bruna, di origine sedimentaria. si noti l’orlo di cemento isopaco, di prima generazione, che circonda il frammento igneo (c1) e il cemento a mosaico, di seconda generazione, che riempie gli spazi intergranulari (c2). viticcio (campione vi 3) nicol incrociati; d) mirmechite (contornata) inclusa nelle areniti di viticcio (campione vi 1). nicol incrociati. mirmechiti sono state rinvenute al monte capanne (soprattutto nella fascia di contatto tra il plutone granodioritico e le rocce incassanti) e a porto azzurro (all’interno dei filoni granodioritici) (marinelli, 1959); e) pseudomorfosi da parte di carbonato, spinta fino alla quasi totale ricristallizzazione con obliterazione della paragenesi originaria, in un incluso di quarzo-arenite (contornato). viticcio (campione vi 6). nicol incrociati; f) cemento “a dente di cane” che contorna sia i clasti carbonatici di origine organica (frammenti di alghe corallinacee), sia quelli silicatici (granuli quarzoso-feldspatici). madonna delle grazie (campione mg 5). nicol paralleli. microscopic features of the aeolianites of the elba island. a) sub-assial section of elphidium sp. (benthonic foraminiphera) in the viticcio arenites (sample vi 8). parallel polars; b) bioclasts (b), built up by coralline algae, are associated to feldspar-bearing hypabissal fragments (i), having porphyritic texture and variolitic fabric. note the low degree of sorting of the rock. madonna delle grazie (sample mg 2). parallel polars; c) a holocrystalline, inequigranular plutonic enclosed (p), built up by quartz and feldspar crystals together with feldspar macro-crystals showing incipient sericitization. it is associated with quartz-arenitic sedimentary enclosed (s), which contain lamellae of brown mica. note the rim of first-generation isopachous cement that surrounds the igneous fragment (c1) along with the second-generation “mosaic” cement that fills the intergranular pores (c2). viticcio (sample vi 3) crossed polars; d) a mirmechite (contoured) inside the viticcio arenites (sample vi 1). crossed polars. mirmechites have been found in the monte capanne area (mainly at the contact between the granodioritic pluton and the country rocks) and in the porto azzurro area (inside the granodioritic necks) (marinelli, 1959); e) carbonate pseudomorph after a quartz-arenitic enclosed (contoured). recrystallization and consequent obliteration of the original paragenesis are almost complete. viticcio (sample vi 6). crossed polars; f) “dogtooth” cement surrounding both the organogenous carbonate clasts (fragments of coralline algae) and the silicate clasts (quartzand feldspar-bearing grains). madonna delle grazie (sample mg 5). parallel polars. d e ignee plutoniche, a composizione granodioritica; aggregati di quarzo, feldspato potassico, plagioclasio, clinopirosseno, con tessitura variabile da intergranulare a variolitica fino a porfiritica: si tratta di frammenti di rocce ignee ipoabissali, a composizione granitica l.s. in generale, fenomeni di alterazione (ossidazione, cloritizzazione, sericizzazione e argillificazione) a spese degli inclusi litici sono comuni in tutti gli affioramenti e riguardano soprattutto le quarzo-areniti e le ipoabissaliti. 5.1.4. cemento sono presenti due generazioni di cemento. un cemento di prima generazione, formato da carbonato di calcio isopaco, spesso pochi µm, contorna i granuli assumendo la forma di “dente di cane”. esso si osserva piuttosto raramente in alcuni campioni di viticcio (fig. 9c), mentre risulta più frequente in quelli di mad.na delle grazie (fig. 9f). un cemento di seconda generazione, formato da carbonato di calcio disposto a mosaico (sparite), riempie generalmente le cavità tra i granuli. il cemento sparitico ha grana variabile da medio-grossolana (barabarca) a medio-fine (viticcio) a fine (mad.na delle grazie, stecchi). 5.2. analisi morfometrica in sezione sottile dei granuli di quarzo l’analisi morfometrica è stata condotta su granuli di quarzo in sezione sottile. i risultati analitici sono quindi riferiti alle due dimensioni. l’analisi è consistita nella misurazione dei diametri maggiore e minore dei granuli, mediante i quali è stata calcolata la sfericità secondo la formula di riley. l’arrotondamento dei granuli è stato valutato utilizzando le tavole comparative di powers (1953). il quarzo è stato scelto come specie mineralogica di confronto in virtù della sua ubiquità nelle rocce in studio e della sua pressoché assoluta indipendenza dai fenomeni di alterazione post-deposizionale, i quali verosimilmente hanno avuto entità diversa in ciascuno degli affioramenti. l’analisi morfometrica è stata eseguita su cristalli di quarzo freschi e integri. non sono stati, quindi, presi in esame cristalli mostranti geminazione, estinzione ondulata, segni di disgregazione meccanica o bordi riassorbiti. sono stati esclusi anche i cristalli raggruppati in glomeruli o appartenenti ad inclusi litici. per ogni campione sono stati analizzati più di cento granuli di quarzo. 5.2.1. dimensioni tra tutte le località del presente studio, i campioni di barabarca sono caratterizzati in generale dalle dimensioni minori e dalla minore dispersione dei dati (dmax = 75 ÷ 375 µm, dmin = 50 ÷ 200 µm). per contro, i campioni di viticcio hanno le dimensioni maggiori e la maggiore dispersione dei dati (dmax = 150 ÷ 1050 µm, dmin = 100 ÷ 525 µm). i parametri dimensionali dei campioni di stecchi (dmax = 50 ÷ 500 µm, dmin = 50 ÷ 400 µm) e mad.na delle grazie (dmax = 75 ÷ 600 µm, dmin = 50 ÷ 350 µm) risultano simili tra loro e intermedi rispetto a quelli delle località precedenti (fig. 10). e’ stata anche determinata la frequenza delle dimensioni dei granuli di quarzo in ciascun affioramento (fig. 11). a barabarca, la maggiore frequenza corrisponde a dimensioni piuttosto piccole [9 granuli aventi 35 fig. 10 – analisi morfometrica dei granuli di quarzo delle eolianiti: diametri massimo e minimo dei granuli, misurati in sezione sottile. morphometric analysis on the quartz grains of the aeolianites: maximum vs minimun diameters of the grains, as measured on rock slides. le eolianiti dell’isola d’elba ... 36 fig. 11 analisi morfometrica dei granuli di quarzo delle eolianiti: frequenza delle dimensioni dei granuli, misurate in sezione sottile, in ciascun affioramento. nella legenda, con lo stesso colore sono indicati i granuli aventi stesse dimensioni. in totale, sono stati analizzati 109 granuli a viticcio, 105 a barabarca, 107 a stecchi e 107 a madonna delle grazie. morphometric analysis on the quartz grains of the aeolianites: frequency of dimensions of the grains in each outcrop, as measured on rock slides. in the caption, each color indicates grains having the same dimensions. in total, 109 grains of viticcio, 105 of barabarca, 107 of stecchi, and 107 of madonna delle grazie have been analyzed. m. d’orefice, r. graciotti & f. capitanio 37 fig. 12 analisi morfometrica dei granuli di quarzo delle eolianiti: frequenza delle classi di sfericità dei granuli in ciascun affioramento. e’ riportato il numero di granuli per ciascuna classe. in totale, sono stati analizzati 109 granuli a viticcio, 105 a barabarca, 107 a stecchi e 107 a madonna delle grazie. morphometric analysis on the quartz grains of the aeolianites: frequency of classes of sphericity of the grains in each outcrop. the number of grains is reported for each class. in total, 109 grains of viticcio, 105 of barabarca, 107 of stecchi, and 107 of madonna delle grazie have been analyzed. le eolianiti dell’isola d’elba ... dimensioni (150 x 100 µm), pari all’8,6 % del totale]. a mad.na delle grazie, la maggiore frequenza risulta spostata verso dimensioni intermedie [7 granuli aventi dimensioni (250 x 100 µm), pari al 6,5 % del totale]. a stecchi, la distribuzione delle frequenze delle misure mostra due massimi [7 granuli aventi dimensioni (150 .x 100 µm) e 9 granuli aventi dimensioni (250 x 150 µm), pari rispettivamente al 7,5 % e all’8,4 % del totale]. per contro, i campioni di viticcio presentano un’ampia omogeneità dei dati senza massimi significativi nella distribuzione della frequenza delle misure. in generale, si evince una marcata differenza nelle dimensioni dei grani di quarzo tra gli affioramenti del promontorio del m. calamita e quelli del golfo di viticcio. 5.2.2. sfericità in generale, i granuli di quarzo presentano un massimo di frequenza in corrispondenza dei valori di sfericità più bassi o intermedi (0,10 ÷ 0,60) (fig. 12). per contro, nelle classi di sfericità più alte la frequenza dei grani è nettamente minore. in particolare, per quanto concerne i valori di sfericità compresi tra 0,70 e 1,00, viticcio possiede un numero di grani leggermente maggiore rispetto agli altri affioramenti del m. calamita, i quali invece risultano molto simili tra loro. in definitiva, le classi di sfericità maggiormente rappresentate sono quelle aventi valori compresi tra 0,20 e 0,40. i campioni di mad.na delle grazie hanno una distribuzione spostata verso valori di sfericità maggiori rispetto agli altri. i campioni di barabarca e viticcio, invece, mostrano una dispersione dei valori relativamente più elevata. 5.2.3. arrotondamento anche i valori stimati dell’arrotondamento (fig. 13) risultano piuttosto uniformi per i vari affioramenti: infatti, si ha una netta prevalenza di granuli di quarzo con grado di arrotondamento da “subangoloso” a “subarrotondato”. nel dettaglio, a stecchi si ha la massima percentuale relativa di granuli appartenenti alla classe “subangoloso” (53,3 %), cui corrisponde la minima percentuale di granuli della classe “subarrotondato” (29,0 %); in questo affioramento, la distribuzione delle classi risulta la più omogenea, in quanto sia la classe “arrotondato” che quella “angoloso” raggiungono valori piuttosto elevati e prossimi tra loro (9,3 % e 8,4 %, rispettivamente). a mad.na delle grazie, si ha ancora una netta prevalenza dei granuli appartenenti alla classe “subangoloso” (52,3 %) rispetto a quelli della classe “subarrotondato” (32,7 %). a barabarca la maggior parte dei granuli è pressoché ugualmente distribuita tra le classi “subangoloso” (44,8 %) e “subarrotondato” (43,8 %). a viticcio, invece, i granuli appartenenti alla classe “subarrotondato” sono leggermente superiori a quelli della classe “subangoloso”. in sostanza, tra gli affioramenti del promontorio del m. calamita e del golfo di viticcio si apprezza una certa differenza solo per quanto concerne i granuli della classe “arrotondato”, che in quest’ultima località raggiungono la loro frequenza minima. 5.3. inclusi litici: analisi quantitativa l’analisi degli inclusi litici è consistita nell’identificazione delle specie mineralogiche costituenti, nella 38 fig. 13 analisi morfometrica dei granuli di quarzo delle eolianiti: percentuale delle classi di arrotondamento dei granuli per ciascun affioramento. in totale, sono stati analizzati 109 granuli a viticcio, 105 a barabarca, 107 a stecchi e 107 a madonna delle grazie. morphometric analysis on the quartz grains of the aeolianites: percentage of classes of roundness of the grains in each outcrop. in total, 109 grains of viticcio, 105 of barabarca, 107 of stecchi, and 107 of madonna delle grazie have been analyzed. a) viticcio b) barabarca c) stecchi d) m. delle grazie m. d’orefice, r. graciotti & f. capitanio definizione delle tessiture e nella determinazione dei rapporti quantitativi relativi delle diverse tipologie di incluso. sono stati selezionati inclusi freschi e integri, escludendo quelli in cui i fenomeni di alterazione e/o ricristallizzazione hanno obliterato la paragenesi originaria. particolare attenzione è stata posta nel caso in cui diversi frammenti della stessa tipologia fossero adiacenti gli uni agli altri: verosimilmente, essi provengono da un solo incluso disgregato in più parti per azione meccanica (questo accade frequentemente a viticcio). per ogni affioramento sono stati analizzati più di cento inclusi. in tutti gli affioramenti (fig. 14), i frammenti di rocce sedimentarie (quarzo-areniti provenienti da rocce flyschoidi) sono preponderanti quantitativamente. a stecchi, l’abbondanza delle quarzo-areniti raggiunge il valore massimo dell’83,6 %, cui corrisponde la percentuale minima di rocce ignee (3,6 %), mentre la percentuale delle rocce metamorfiche è del 12,7 %. a mad.na delle grazie, le areniti sedimentarie (75,0 %) sono ancora prevalenti rispetto alle rocce ignee (13,4 %) e a quelle metamorfiche (11,6 %). a barabarca, le quarzo-areniti costituiscono il 72,6 % degli inclusi, seguite dalle rocce ignee (16,2 %), mentre la percentuale di rocce metamorfiche si mantiene pressappoco costante (11,1 %, in prevalenza quarziti rispetto a quarzoscisti). a viticcio, la distribuzione delle diverse tipologie di inclusi risulta molto simile a quella di barabarca: la sola differenza consiste nella maggiore percentuale di scisti (quarzoscisti e micascisti) rispetto alle quarziti. di rilevante interesse è la quasi totale assenza di frammenti carbonatici di origine inorganica. 5.4. litologia del substrato per accertare una eventuale influenza delle rocce del substrato nella composizione degli elementi granulari che costituiscono i depositi eolici, è stata definita la distribuzione dei litotipi in ciascuno degli affiora39 fig. 14 classificazione genetica e quantità percentuali degli inclusi litici delle eolianiti. in totale, sono stati analizzati 133 inclusi a viticcio, 117 a barabarca, 110 a stecchi e 112 a madonna delle grazie. genetic classification and quantitative percentages of lithics included inside the aeolianites. in total, 113 lithics of viticcio, 117 of barabarca, 110 of stecchi, and 112 of madonna delle grazie have been analyzed. a) viticcio b) barabarca c) stecchi d) m. delle grazie le eolianiti dell’isola d’elba ... menti del presente studio. la misura della distribuzione dei litotipi del substrato è stata condotta mediante l’utilizzo di analisi spaziali quantitative in ambiente gis (åberg et al., 2007), applicate alla carta geologica dell’isola d’elba alla scala 1:25.000 (barberi et al., 1967a). per ogni deposito, quindi, è stato delimitato il relativo bacino idrografico, all’interno del quale è stata misurata la percentuale dei vari litotipi affioranti. i risultati rivelano una eterogeneità litologica nei diversi bacini (fig. 15). infatti, a barabarca predominano i litotipi arenacei e carbonatici che costituiscono il flysch cretacico (55,2 %) rispetto alle quarziti del verrucano (43,3 %). a stecchi, la situazione è leggermente diversa, con le rocce del flysch cretacico (38,8 %) subordinate alle quarziti del verrucano (56,6 %). per contro, a mad.na delle grazie la litologia del substrato è più complessa rispetto ai due bacini precedenti: sono presenti prevalentemente carbonati triassici di ambiente evaporitico (45,6 %), oltre agli scisti e filladi del calamita (22,2 %) e alle rocce del flysch cretacico (21,4 %). il bacino viticcio si differenzia ulteriormente dagli altri, poiché è costituito, quasi nella stessa percentuale, da litotipi appartenenti al flysch cretacico (55,0 %) e da porfidi (45,0 %). 6. discussione 6.1. caratteri sedimentari le eolianiti sono caratterizzate da diverse strutture sedimentarie, tra le quali la più importante ai fini diagnostici è la stratificazione incrociata a grande scala. ad essa sono associati altri aspetti sedimentari, come: • l’elevata inclinazione dei foreset, in genere immergenti verso terra con pendenze fino a 35°; • l’orientamento molto variabile dei singoli foreset nell’ambito di uno stesso affioramento. queste peculiarità, unite alla presenza di intercalazioni di depositi di versante e di paleosuoli, sono indicative di un ambiente deposizionale continentale, in gran parte dominato dai processi eolici. ulteriori indagini microscopiche, finalizzate a verificare la presenza nelle eolianiti di strutture a piccola scala tipiche dei depositi eolici, quali laminazioni di tipo pinstripe (hunter, 1977; 1993), non hanno dato esito positivo. l’eventuale assenza, in sezione sottile, di laminazioni di questo tipo può essere probabilmente attribuita a difficoltà nella classazione dei granuli. infatti, la presenza di un’abbondante frazione bioclastica, eterogenea in forma, dimensioni e densità, rende problematico il sorting dimensionale dei granuli (kindler & davaud, 2001; le guern & davaud, 2005). inoltre, alla scala dell’affioramento, il generalizzato stato di alterazione delle sezioni delle eolianiti esposte, ha reso difficoltosa l’osservazione di stratificazione da grainflow o da grainfall. per quanto concerne la disposizione dei corpi sedimentari in esame, il loro accumulo a ridosso degli acclivi versanti rocciosi della fascia costiera ed il loro protendersi nell’entroterra elbano, in alcuni casi oltre i 100 m di quota s.l.m., induce a ritenere che questi litosomi siano stati originati da climbing dunes. le superfici s1 e s2, osservate alla spiaggia della madonna (fig. 2b-c), sono riconducibili a superfici d’erosione generate da intense dinamiche di versante, in 40 fig. 15 classificazione genetica e quantità percentuali dei tipi litologici del substrato affiorante nei bacini idrografici dei depositi eolici in esame (dati desunti dalla carta geologica dell’isola d’elba 1:25.000 – barberi et al., 1967a). la varietà del substrato è tale da comprendere rocce sedimentarie appartenenti a diverse formazioni (qtz-areniti: verrucano, triassico; calcari e dolomie: evaporiti, triassico; areniti, calcari e marne: flysch, cretacico), oltre a rocce ignee (graniti e granodioriti) e metamorfiche (scisti e gneiss del calamita). genetic classification and quantitative percentages of lithotypes of the substrate outcropping in the hydrographical basins of the aeolian deposits (data derived from the geological map of the elba island 1:25.000 – barberi et al., 1967a). the variability of the substrate is high, as it includes sedimentary rocks belonging to several formations (qtz-arenites: verrucano, triassic; limestones & dolostones: evaporites, triassic; arenites, limestones & marls: flysch, cretaceous), together with igneous (granites & granodiorites) and metamorphic rocks (scists & gneisses of monte calamita). a) viticcio b) barabarca c) stecchi d) m. delle grazie m. d’orefice, r. graciotti & f. capitanio grado di troncare la porzione superiore della duna accumulata contro il versante e di ridistribuire i sedimenti verso valle. questo aspetto è ben documentato nella superficie superiore (s2), che corrisponde al troncamento della parte superiore della duna “b”, sulla quale poggiano detriti stratificati di versante. nel caso della spiaggia della madonna, l’angolo di arrampicata (angle of climbing) dei corpi dunari, ottenuto dal rapporto tra il tasso di migrazione sottovento della duna e il tasso di accumulo verticale (rubin & hunter, 1982), risulta pari a circa 10°. il valore non eccessivamente elevato di quest’angolo può spiegare perché si è preservata solo la porzione inferiore del pacco di foreset. le superfici di discontinuità, di ordine minore, presenti all’interno dei set a stratificazione incrociata sono superfici di riattivazione dovute ad una interruzione periodica della migrazione della duna e all’erosione sul lato frontale (lee face) della stessa ad opera di venti subordinati rispetto a quelli dominanti. riguardo le concrezioni intrasedimentarie (fig. 4), una possibile interpretazione genetica è che si tratti di rizoconcrezioni, cioè impronte calcificate di apparati radicali appartenenti ad un’antica vegetazione dunare. a questo proposito, occorre tener presente che le radici possono svilupparsi nel terreno non solo in direzione verticale ma anche orizzontale. tuttavia, una interpretazione alternativa è quella avanzata da mazzanti & parea (1977) e parea (1984), per cui le concrezioni sub-orizzontali sarebbero da mettere in relazione con le acque della falda freatica in lento deflusso verso le quote più basse entro la porzione basale dei sedimenti. invece, le concrezioni verticali sarebbero da attribuire essenzialmente al percolamento delle acque meteoriche, attraverso la parte superiore degli stessi sedimenti, durante la discesa verso la falda freatica. infine, mc bride & parea (2001) ammettono la possibilità che molte concrezioni verticali si siano originate da rizoconcrezioni, composte inizialmente da calcite micritica, interessate successivamente da precipitazione di calcite spatica ad opera delle acque vadose percolanti. ciò spiegherebbe il considerevole sviluppo laterale e la coalescenza di queste strutture sedimentarie. per quanto concerne il paleosuolo rosso intercalato alle eolianiti affioranti tra barabarca e stecchi (fig. 5a), la sua origine pedogenetica è testimoniata da un’intensa rubefazione, da una decarbonatazione molto spinta, dall’esistenza di materia organica e dall’arricchimento in argilla. il paleosuolo, probabilmente sviluppatosi a spese dei sottostanti depositi eolici con livelli detritici intercalati, è stato classificato da cremaschi & trombino (1998) come un “red mediterranean soils – xeralfs”. infine, i livelli detritici associati alle eolianiti in diverse posizioni stratigrafiche (fig. 5b, 6a-b), sono da riferire alla vicinanza di un versante in degradazione, che ha fornito il materiale detritico in condizioni climatiche verosimilmente più fredde e più aride di quelle attuali. infatti, la formazione di questi detriti può essere favorita dalla scarsa copertura vegetale associata a processi crioclastici più o meno intensi. questa ipotesi è confermata dalla presenza, nell’affioramento di spiaggia della madonna, di detriti di versante clinostratificati secondo strati piano-paralleli (éboulis ordonnés) noti in letteratura per essersi deposti in un ambiente freddo ed arido, caratterizzato da versanti quasi del tutto denudati. 6.2. caratteri bio-minero-petrografici il costituente micropaleontologico dei campioni analizzati nel presente studio (tab. 2), mostra la prevalenza di miliolidae accanto a forme quali lobatula lobatula (walker & jacob), elphidium advenum (cushmann), planorbulina mediterranensis (cushmann) e rosalina bradyi (cushmann), tutte di acque relativamente basse e legate al popolamento vegetale, come pure di discorbis globularis (d’orbigny), forma sessile infralitorale (blancvernet, 1969; murray, 1973; violanti et al., 1988). questa associazione microfaunistica è riferibile ad un ambiente marino infralitorale temperato caldo, dove la componente vegetale di alghe e/o di posidonia è non trascurabile. da un punto di vista generale, la mineralogia delle eolianiti non è direttamente confrontabile con quella del substrato, affiorante nei bacini idrografici in cui sono compresi i depositi eolici. a barabarca, e in quantità minore a mad.na delle grazie, le eolianiti contengono granato (con caratteri ottici corrispondenti a termini ricchi in ferro: andradite-grossularia): considerando la litologia del promontorio del m. calamita, le più probabili rocce-madri dei granati sono le cornubianiti e in subordine gli scisti. ancora, a viticcio il granato non è stato rinvenuto, e risulta pure assente nelle rocce del substrato. per quanto riguarda l’anfibolo (con i caratteri ottici dell’orneblenda l.s.), quello delle eolianiti di stecchi può provenire dalle anfiboliti presenti nel promontorio del m. calamita, mentre la provenienza di quello di viticcio rimane incerta, in quanto non sono stati finora segnalati in letteratura rinvenimenti di anfibolo nel substrato del golfo di viticcio. la mancanza di correlazione minero-petrografica tra le eolianiti e il substrato dei bacini idrografici in cui sono comprese, è evidente anche dall’analisi degli inclusi litici delle eolianiti. infatti, il contenuto percentuale di inclusi sedimentari, ignei e metamorfici si mantiene pressappoco costante in tutti gli affioramenti appartenenti sia allo stesso settore (barabarca, stecchi, mad.na delle grazie) sia a settori distinti (golfo di viticcio e promontorio del calamita). per contro, la litologia del substrato è estremamente variabile non solo da un’area all’altra (ad esempio, nel golfo di viticcio il substrato è composto per metà circa da rocce ignee, del tutto subordinate negli altri affioramenti esaminati), ma anche all’interno di una stessa area (ad esempio, a mad.na delle grazie un quarto circa del substrato è composto da rocce metamorfiche, praticamente assenti negli altri affioramenti). le indagini morfometriche eseguite in sezione sottile sulla frazione fine quarzosa delle eolianiti hanno rivelato alcune tendenze. infatti, i dati ottenuti risultano piuttosto omogenei, soprattutto per quanto riguarda la sfericità (medio-bassa) e l’arrotondamento (da “subangoloso” a “subarrotondato”). alcune differenze si riscontrano per le dimensioni dei grani misurate al microscopio: tra le località del presente studio, barabarca possiede la popolazione più omogenea e a dimensioni minori, mentre viticco possiede la popolazione più eterogenea che raggiunge le dimensioni mag41le eolianiti dell’isola d’elba ... giori. le analisi morfometriche suggeriscono una certa differenza tra gli affioramenti del m. calamita e quelli di viticcio. infatti, i campioni prelevati nelle località di barabarca, stecchi e mad.na delle grazie, presentano caratteristiche morfometriche piuttosto omogenee tra loro e lievemente differenti da quelli di viticcio. queste differenze morfometriche potrebbero essere imputate alla diversa collocazione geografica ed alla diversa esposizione dei due settori presi in esame (promontorio del m. calamita e golfo di viticcio). in particolare, i fattori maggiormente influenti potrebbero essere stati la differente granulometria del materiale messo a disposizione dalla dinamica marina ed in misura minore da quella fluviale, oltre alla diversa capacità di trasporto e direzione dei venti dominanti. il cemento isopaco a “dente di cane” (fig. 9f) è indicatore di condizioni freatiche, che possono essere considerate di tipo meteorico (ambiente continentale). infine, la quasi totale assenza di clasti carbonatici all’interno delle eolianiti è un elemento rilevante. pur essendo gli extraclasti assai poco resistenti alla degradazione meccanica e chimica, è difficile ammettere una loro completa assenza. in ogni caso si sottolinea che le rocce carbonatiche, seppur ben rappresentate nel settore del m. calamita esaminato, costituiscono una minima percentuale nell’intero contesto geologico dell’isola d’elba. di fatto, la composizione mineralogica delle eolianiti punta ad una provenienza dei sedimenti da litotipi quarzo-arenitici (flyschoidi), frammisti a materiale bioclastico originatosi in ambiente di mare poco profondo. in quest’ambiente, sotto l’influsso della dinamica marina, è avvenuta la redistribuzione dei sedimenti provenienti dall’erosione del substrato continentale elbano e la commistione con quelli di origine marina. in definitiva, l’area sorgente degli elementi costitutivi delle eolianiti in studio, può essere individuata nei bassi fondali marini della piattaforma continentale circostante l’isola d’elba. 7. conclusioni i depositi eolici affioranti nel tratto di costa occidentale del m. calamita e nel golfo di viticcio dell’isola d’elba si sono formati in periodo di basso stazionamento marino. infatti, la loro prosecuzione per diversi metri al di sotto dell’attuale livello del mare e la loro erosione ad opera dell’odierna dinamica marina, confermano un equilibrio di questi corpi sedimentari con una linea di costa più avanzata di quella attuale. inoltre, anche i versanti rocciosi su cui tali depositi poggiano in discordanza e i fondovalle che essi stessi colmano, appaiono morfologicamente legati ad un livello di base più basso di quello odierno. lo sviluppo delle dune eoliche in esame è strettamente connesso alla disponibilità di un’abbondante quantità di sabbia da parte dei venti dominanti, i quali debbono essere dotati di una sufficiente capacità di trasporto per rimuovere le particelle di sabbia o di ghiaia minuta. tali particelle, comunque, affinché possano essere asportate dal vento, devono essere abbastanza asciutte e non devono aver subito nel frattempo processi di stabilizzazione da parte della vegetazione o di cementazione ad opera delle acque meteoriche circolanti o di altri fenomeni diagenetici. tutte queste specifiche condizioni possono verificarsi nel corso di una fase di regressione marina, durante la quale lentamente e progressivamente emerge dal mare un fondale sabbioso. tale fondo, appartenente alla vasta piattaforma continentale toscana oggi sommersa, costituisce un’idonea zona d’alimentazione di questi materiali, i quali, sospinti dai venti dominanti, sono in grado di risalire i versanti e le preesistenti valli fluviali fino ad oltre 100 m sul livello del mare attuale. la presenza delle eolianiti elbane, sia sulle coste esposte ad ovest e sia su quelle esposte ad est, induce ad ipotizzare una provenienza dei venti dominanti oltre che dai quadranti occidentali, anche da quelli orientali. ciò è in accordo con quanto osservato da antonioli & ferranti (1992) nei riguardi delle eolianiti affioranti lungo il tratto meridionale del golfo di orosei (sardegna orientale). l’ipotesi che le eolianiti elbane si siano formate successivamente ad un periodo caldo è in accordo con la presenza in questi litotipi di bioclasti appartenenti ad associazioni microfaunistiche totalmente di ambiente marino litorale temperato-caldo. i sedimenti accumulati lungo la piattaforma continentale durante una fase calda interglaciale, sarebbero stati erosi dai venti dominanti nel corso della successiva fase di basso stazionamento marino e accumulati nell’entroterra, insieme ai materiali rimaneggiati dai corsi d’acqua, sotto forma di cordoni dunari. pertanto, in base a quanto su esposto, alle età radiometriche dei paleosuoli intercalati nelle eolianiti affioranti in località mad. na delle grazie e cala cancherelli ed alla presenza di manufatti musteriani all’interno dei paleosuoli, si può ipotizzare che la messa in posto dei sedimenti del presente studio sia legata, in accordo con cremaschi & trombino (1998), a fasi fredde ed aride registratesi nel corso degli stadi isotopici 4 e 2 dell’ultimo glaciale. l’età di formazione dei depositi in esame è quindi riferibile al pleistocene superiore. il paleosuolo si è probabilmente sviluppato durante una fase interstadiale meno fredda e più umida (stadio isotopico 3), che ha favorito la crescita di una vegetazione dunare e la pedogenizzazione delle eolianiti. la presenza, nelle aree esaminate, di depositi di versante, alternati ad eolianiti, sta ad indicare una temporanea disattivazione della sedimentazione eolica. essa potrebbe coincidere con l’inizio di una deposizione, ad opera dei processi fluvio-denudazionali di versante, di materiali provenienti in parte dal dilavamento delle sabbie eoliche precedentemente deposte ed in parte dall’erosione dei soprastanti versanti modellati nel substrato roccioso. ringraziamenti si ringrazia g. ventura per le analisi micropaleontologiche, m. cacopardo per le sezioni sottili e s. falcetti per il disegno. un ringraziamento particolare va a m. coltorti per i preziosi e puntuali suggerimenti forniti, nonché a c. carrara e f. antonioli per la revisione critica del manoscritto. 42 m. d’orefice, r. graciotti & f. capitanio bibliografia åberg u., cipolloni c., d’orefice m. & graciotti r. 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(1982) the tyrrhenian sea: a rifted kricogernic-swell basin. mem. soc. geol. it., 24, pp. 531-568. 44 ms. ricevuto il 4 gennaio 2007 testo definitivo ricevuto l’8 marzo 2007 ms. received: january 4, 2007 final text received: march 8, 2007 m. d’orefice, r. graciotti & f. capitanio imp.03saroli nuovi dati paleosismologici dal settore orientale del bacino del fucino (italia centrale) michele saroli1, marco moro2, hermann borghesi3, daria dell’acqua4, fabrizio galadini5, paolo galli6 1 dipartimento di meccanica, strutture, ambiente e territorio, università di cassino, e-mail: michele.saroli@unicas.it 2 istituto nazionale di geofisica e vulcanologia 3 cooperativa limes, avezzano 4 coll. esterno istituto nazionale di geofisica e vulcanologia, roma 5 istituto nazionale di geofisica e vulcanologia, milano 6 dipartimento della protezione civile, roma. riassunto: m. saroli et al., nuovi dati paleosismologici dal settore orientale del bacino del fucino (italia centrale). (it issn 03943356, 2008). l’analisi di depositi del pleistocene superiore-olocene in due cave a ridosso della faglia san benedetto dei marsi-gioia dei marsi (bacino del fucino, appennino centrale) ha consentito di ottenere informazioni paleosismologiche che integrano quanto già pubblicato in materia alla fine del secolo scorso. in entrambi gli affioramenti sono stati osservati sedimenti colluviali, alluvionali e lacustri deposti successivamente al tardiglaciale (14-15 ka bp). vincoli cronologici per le successioni individuate vengono da una datazione radiocarbonio (1466-1372 b.c., età calibrata a 2 sigma), da numerose determinazioni archeologiche su materiali ceramici attribuiti all’eneolitico e all’età del bronzo e dal rinvenimento di una fossa di cottura inquadrabile nello stesso ambito cronologico. le unità stratigrafiche identificate sono in contatto per faglia con il substrato carbonatico. il trascinamento dei sedimenti lungo i piani di faglia principali e le dislocazioni osservate lungo piani di taglio secondari definiscono l’attività olocenica di questo settore della faglia san benedetto dei marsi-gioia dei marsi. l’analisi del primo fronte di scavo ha fornito l’evidenza di tre eventi di dislocazione di cui il più recente avvenuto successivamente alla deposizione dell’unità colluviale con frammenti ceramici preistorici. l’analisi del secondo fronte di scavo ha ugualmente permesso di identificare tre eventi di dislocazione di cui il più recente interessa l’unità nella quale è stata scavata la fossa di cottura. due dei tre eventi identificati potrebbero corrispondere a due dei tre più antichi eventi dell’olocene identificati nei precedenti lavori e avvenuti all’incirca tra 5 e 10 ka bp. l’evento più recente potrebbe invece essere associato a quello già riferito all’intervallo 1500-1300 a.c., e/o ai due eventi successivi, vale a dire quello riferibile alla tarda antichità-alto medioevo (426–782 d.c., età 14c cal. in galadini e galli, 1999) e quello avvenuto nel 1915. infine, l’entità del rigetto verticale ha permesso di valutare un rateo minimo di movimento dell’ordine di 0.14-0.35 mm/a. abstract: m. saroli et al., new paleoseismological data from the fucino basin (central italy). (it issn 0394-3356, 2008). the fucino plain represents the area with the best italian paleoseismological record. this is mainly due to the fact that, differently from other apennine cases, late pleistocene-holocene faults border and affect a lacustrine basin which has been persistent throughout the late pleistocene-holocene until the 19th century. thanks to this almost continuous stratigraphical record, galadini and galli (1999) described the complete displacement history of the fucino fault, which finally activated in 1915, causing a mw=7.0 earthquake. these authors also identified six previous holocene events (with recurrence intervals of 1,400-2,600 years), and three others occurred in the upper late pleistocene. on the whole, the fucino paleoseismological record consists of ten events (including the 1915 one) in the past 32,500 years. human works, especially those related to the excavation of foundations, extraction from quarries and cleaning of the drainage network, gave the opportunity to study new outcrops of paleoseismological interest. the recent analysis of two quarry walls located along the western flank of the basin (i.e. where the surficial expression of one of the main faults is located) has provided data which corroborate the previous studies. alluvial gravels deposited along the shoreline of the lake and colluvial deposits outcrop in both quarries. unit 1 of quarry-wall fs1 is made of matrix supported gravel, with pottery shards attributed to 3000-1500 b.c., whereas the radiocarbon dating of the organic matrix gave 1466-1372 cal b.c. (2 sigma). unit 2, whose origin is uncertain (alluvial deposits accumulated and reworked along the lacustrine shoreline?), is made of gravel included in silty-sandy matrix. apart from sub-unit 3b, unit 3 is prevalently made of gravel and coarse sand due to alluvial deposition close to the lacustrine shoreline. based on the available literature (giraudi, 1988, 1999a), it deposited at the end of the late pleistocene. sub-unit 3b is particularly significant for the paleoseismological analysis, since it has been interpreted as a colluvial wedge originated from the erosion of a coseismic fault scarp. unit 4, made of clast-supported gravel, probably represents a shoreline deposit. the relationship between the fault planes and the described succession suggests that at least three events of displacement occurred after the deposition of sub-unit 3d, the oldest one being related to the colluvial wedge (unit 3b) and the youngest being represented by the displacement of the entire succession (including unit 1 containing the pottery shards). the other quarry wall (fs2) shows archaeological remains (inside unit 2) below the present soil (unit 1). these remains are basically represented by a pit-fire containing fragments of pottery shards attributed to the eneolithic and the bronze age (3000-1500 b.c.). the characteristics of the unit 3 gravel indicate deposition along the shoreline, while unit 4 (gravel in sandy matrix) has been interpreted as a colluvial wedge deposited from a coseismic scarp. finally, unit 5 represents the result of the re-organisation of alluvial gravel by the lacustrine shoreline water. from a chronological point of view, this unit can be compared to unit 3 of fs1, i.e. it deposited at the end of the late pleistocene. the analysis of the relationship between the fault planes and the stratigraphic units defines at least three displacement events, the intermediate being represented by the deposition of the colluvial wedge and the ultimate(s) by the displacement of unit 3 within which the pit-fire has been excavated. on the whole, the oldest and the intermediate events may represent two of the three oldest holocene events identified by galadini and galli (1999), which occurred between 5 and 10 ka bp. indeed, the oldest displaced units, based on the available literature (giraudi, 1988; 1999a), deposited after 14-15 ka bp. the most recent event(s), besides the 1915 rupture, may be associated to the event dated at 1500-1300 b.c. by galadini and galli (1999) and/or, considering the displacement affecting unit 1 (fs1), to the penultimate holocene event dated at the late antiquity/early middle ages (426 – 782 a.d., cal. age 14c in galadini and galli, 1999). finally, the amount of displacement and the chronological constraints permit us to define vertical displacement rates not exceeding 0.35 mm/yr for the main fault of fs1 and 0.14 mm/yr for the main fault of fs2. parole chiave: paleosismologia, faglia attiva, sismotettonica, piana del fucino, italia centrale. keywords: paleoseismology, active fault, seismotectonics, fucino plain, central italy. il quaternario italian journal of quaternary sciences 21(1b), 2008 383-394 384 m. saroli et al. 1. introduzione l’appennino abruzzese è stato interessato da numerosi terremoti distruttivi. tra questi, il terremoto del 13 gennaio 1915 (maw=6.99, gruppo di lavoro cpti, 2004), responsabile di più di 30.000 vittime, è stato causato dall’attivazione di faglie che interessano il bacino del fucino (es. galadini and galli, 1999), area indagata nel presente studio. le numerose analisi paleosismologiche condotte in questa zona hanno permesso di caratterizzare il comportamento sismogenetico dell’area con notevole dettaglio (michetti et al., 1996; galadini et al., 1997a e 1997b; galadini e galli, 1999). l’analisi paleosismologica recentemente effettuata su nuovi affioramenti di unità del pleistocene superiore – olocene all’interno di due cave ha consentito di arricchire ulteriormente il già dettagliato quadro degli eventi paleosismici occorsi nell’area del fucino. il lavoro ha riguardato la fascia pedemontana dei rilievi che bordano il fianco orientale del bacino, lungo la faglia gioia dei marsi–san benedetto dei marsi, uno dei segmenti che costituiscono l’espressione superficiale della sorgente del terremoto del 1915. dopo una raccolta di dati bibliografici (paleosismologici e archeologici) utili alla definizione delle attuali conoscenze dell’area in studio, si è proceduto all’analisi stratigrafico-strutturale di fronti di scavo (fs1 e fs2) delle due cave citate. i vincoli cronologici sono stati ottenuti grazie a una datazione radiocarbonio di materiale organico e determinazioni archeologiche di frammenti ceramici attribuiti al neolitico, eneolitico e all’età del bronzo. nei capitoli seguenti sono discusse le varie implicazioni derivate dall’interpretazione dei dati acquisiti, soprattutto per quanto concerne l’inquadramento cronologico dei singoli eventi di dislocazione individuati. 2. inquadramento geologico e geomorfologico del bacino del fucino l’area di studio è ubicata nel comune di pescina, frazione venere dei marsi, nel settore orientale della piana del fucino, in località le coste (figg. 1 e 2). la piana del fucino (circa 660 m s.l.m.) rappresenta l’alveo del lago storico, prosciugato nel xix secolo, ospitato in un bacino tettonico di tipo semi-graben (es. galadini e messina, 1994), controllato da sistemi di faglie dirette prevalentemente con andamento no-se e ne-so. il bacino è delimitato ad e e ad o da dorsali montuose orientate no-se con quote massime che raggiungono i 2300 m s.l.m. (fig. 1). i versanti sono scolpiti prevalentemente su formazioni carbonatiche meso-cenozoiche e depositi plio-quaternari di origine colluviale, alluvionale e lacustre. questi depositi sono discordanti sul substrato marino e si rinvengono in affioramenti discontinui (galadini e messina, 1994; bosi et al., 1996). la stratigrafia dei depositi degli ultimi 30.000 anni e le forme ad essi legate sono riferibili alla dinamica del livello lacustre, con il susseguirsi di fasi di alto e basso stazionamento. la complessa successione di forme e depositi è ampiamente descritta in giraudi (1988), cui si rimanda per l’approfondimento. per quanto riguarda l’area di venere dei marsi, zona oggetto del presente studio, la stratigrafia degli ultimi 20.000 anni è definita da giraudi (1995). essa è rappresentata da una successione di depositi di versante, presenti alla base dei rilievi, organizzati in coni o falde e poggianti sia su depositi lacustri risalenti all’ultimo massimo glaciale sia su terrazzi lacustri più recenti. nell’insieme, l’autore citato definisce cinque formazioni detritiche di età, dalla più antica, pari a 18 – 14 ka (“1a formazione”), 14 – 5.5 ka (“2a formazione”), <5 ka (“3a formazione”), �2.7 ka (“4a formazione”), e più recente del i sec. d.c., per via del ritrovamento, al suo interno, di frammenti di ceramica di età romana imperiale (“5a formazione”). 3. evoluzione cinematica e caratteristiche sismotettoniche dell’area fucense l’attuale assetto strutturale del bacino del fucino è il risultato di una complessa storia tettonica legata all’attività, a partire dal pliocene, di due sistemi di faglie normali, uno con direzione ne-sw, l’altro orientato nw-se. tali sistemi hanno avuto, in momenti diversi, il ruolo di faglie primarie nell’evoluzione strutturale del bacino. l’assetto di questa grande depressione intermontana è pertanto assimilabile a quello derivante dalla sovrapposizione di due semi-graben con diversa orientazione (es. galadini e messina, 1994). al primo dei sistemi sopra citati appartiene la faglia dei tre monti (tmfz in fig. 1), lunga all’incirca 7 km, che rappresenta il segmento più occidentale del più importante sistema di faglie avezzano–bussi. questa faglia, attiva dal pliocene, è responsabile della nucleazione del bacino. ad essa è imputabile, infatti, la fase più antica di strutturazione, consistita nella formazione di un semi-graben con asse ne-sw (es. galadini e messina, 1994). a partire dal pliocene (superiore?) il ruolo primario nell’evoluzione del bacino è stato ricoperto dalle faglie con direzione no-se. questo sistema, lungo il bordo orientale della depressione, è stato responsabile dell’evoluzione più recente del bacino, consistita nella strutturazione di un semi-graben con asse no-se, sovrapposto al precedente. il sistema è costituito dalle faglie normali s.benedetto dei marsi-gioia dei marsi (sbgf in fig. 1), della s.s. marsicana (smf in fig. 1) e monte velino-m.ti della magnola (vmf in fig. 1), disposte in relazione geometrica en-echelon (step destro ). probabilmente, i vari segmenti rappresentano le espressioni superficiali di un'unica struttura sismogenetica con direzione no-se, lunga più di 30 km, che interessa il versante nordorientale dell’intera depressione (galadini et al., 1998). in alternativa a questa interpretazione, la faglia monte velino-m.ti della magnola è stata considerata come l’espressione di una sorgente sismogenetica distinta da quella la cui emergenza è rappresentata dalle prime due faglie citate (boncio et al., 2004). numerosi lavori paleosismologici hanno individuato le tracce geologiche di eventi sismici (evidenze di ripetute fogliazioni superficiali) che hanno interessato il bacino del fucino negli ultimi 30 ka. per quel che riguarda gli eventi di fagliazione tardo pleistocenici, il più antico documentato ha un’età compresa tra 32 ka e 20 ka b.p. ed è stato riconosciuto in un affioramento nei pressi di casali d’aschi, lungo la faglia san benedetto dei marsi–gioia dei marsi (galadini et al., 1997a; galadini e galli, 1999). un’altra dislocazione cosismica, definita tramite l’analisi di uno scavo realizzato attraverso la faglia della s.s. marsicana e docu385nuovi dati paleosismologici ... mentata in numerosi lavori (giraudi, 1988; galadini et al., 1995; galadini et al., 1997a; galadini e galli, 1999), è riferibile a ca. 20 ka b.p. (19.100±650 anni b.p., età 14c). il più recente evento di dislocazione pre-olocenico, registrato sulla faglia di trasacco, è datato 15.66614.397 a.c. (età 14c calibrata), con entità del rigetto fig. 1 schema delle faglie ad attività quaternaria dell’area compresa tra la valle del fiume sangro e campo felice: of, faglia di ovindoli; vmf, faglia m.velino-m.ti della magnola; tmfz, zona di faglia dei tre monti; acf, faglia avezzano-celano; smf, sistema di faglie della s.s. marsicana; pmgf, faglia stazione di pescina-madonna delle grazie; sbgf, faglie s.benedetto dei marsi-gioia dei marsi; tf, faglia di trasacco; lf, faglia di luco dei marsi; asff, sistema di faglie alto sangro-fucino. l’asterisco definisce l’area indagata. map of the quaternary faults in the area between the sangro river valley and the campo felice basin: of, ovindoli fault; vmf, mt.velino-magnola mts. fault; tmfz, tre monti fault zone; acf, avezzano-celano fault; smf, marsicana highway fault system; pmgf, pescina railway station-madonna delle grazie fault; sbgf, s.benedetto dei marsi-gioia dei marsi fault; tf, trasacco fault; lf, luco dei marsi fault; asff, alto sangro-fucino fault system. the asterisk indicates the investigated area. superiore ai 70 cm (galadini e galli, 1999). ad esso è attribuita la dislocazione della spianata di abrasione di avezzano, modellata 18-20 ka anni fa (giraudi, 1988). le indagini paleosismologiche hanno permesso di individuare 7 eventi di dislocazione avvenuti nel corso dell’olocene. i tre eventi più antichi, assai evidenti in alcuni scavi attraverso la faglia di trasacco, sono avvenuti tra due età limite: 10.729-10.053 a.c. e 5.979-5.576 a.c., definite con datazioni radiocarbonio (galadini et al., 1997a; galadini e galli, 1999). un quarto evento, documentato in tre scavi effettuati attraverso la faglia di trasacco, è datato a 3944–3618 anni a.c. (età 14c cal.; galadini et al., 1997a; galadini e galli, 1999). a un quinto evento di dislocazione viene attribuita l’età 1600–1400 anni a.c. (galadini et al., 1997a; galadini e galli, 1999). il penultimo evento olocenico risale alla tarda antichità o all’alto medioevo (426–782 d.c., età 14c cal. in galadini e galli, 1999; individuato anche nello studio paleosismologico di michetti et al., 1996) e viene tentativamente riferito al terremoto che nel 508 d.c. causò danni significativi al colosseo in roma (galadini e galli, 1996). il più recente evento sismico determinato dall’attivazione delle faglie oggetto di questo studio ha interessato il bacino del fucino il 13 gennaio 1915 (serva et al., 1986; michetti et al., 1996; galadini e galli, 1999), ha avuto una magnitudo pari a 7.0, è stato responsabile di ingenti danni in tutta l’area e ha causato danni anche a roma (molin et al., 1999). l’epicentro di questo terremoto è ubicato tra gioia dei marsi e ortucchio (working group cpti, 2004). grazie agli studi paleosismologici, alla ricostruzione del quadro strutturale compatibile col regime tettonico in atto e al confronto tra questo e la distribuzione del danno, si è giunti alla conclusione che il terremoto sia stato generato dalla rottura in profondità di una sorgente lunga oltre 30 km, la cui espressione superficiale è rappresentata dalle faglie di san benedetto dei marsigioia dei marsi, della s.s. marsicana e, presumibilmente, m. velino–m.ti della magnola (galadini et al., 1998). come osservato, movimenti verticali hanno anche interessato faglie secondarie, come quelle di trasacco e di luco dei marsi (galadini e galli, 1999). il tempo di ricorrenza di eventi di dislocazione cosismici in quest’area è tra i 1400 e i 2600 anni, dato affine a quelli disponibili per altre faglie attive appenniniche (galadini e galli, 2000). 4. analisi paleosismologiche le analisi paleosismologiche al margine orientale della piana del fucino (fig. 2) sono state condotte lungo i fronti di scavo fs1 e fs2 di due cave, in prossimità del contatto tettonico tra il substrato carbonatico e i depositi alluvionali-lacustri e colluviali tardo-quaternari. gli affioramenti, una volta puliti e resi il più possibile verticali, sono stati attrezzati con un reticolo a maglia regolare, che ha consentito di effettuare rilievi su carta millimetrata e di rappresentare alla scala 1:50, su una base fotografica vincolata dalla geometria del reticolo, le strutture e le unità stratigrafiche che caratterizzano le pareti oggetto dello studio. l’età dei paleoeventi è stata vincolata sulla base di una datazione 14c effettuata su un campione (cavs1) prelevato dal fronte di scavo fs1 e da determinazioni archeologiche su frammenti ceramici. l’analisi sul terreno ha consentito di definire le relazioni tra i vari piani di taglio individuati e le unità stratigrafiche al fine di definire la successione degli eventi di dislocazione. 4.1 fronte di scavo 1 (fs1) questa parete (l = 10 m; h = 8 m) ha direzione circa e-o, obliqua rispetto all’andamento generale del versante (orientato nno-sse). e’ ubicata a quota 690 m e si trova all’interno di una cava in sfruttamento, sita tra il km 12 e il km 13 della s.s. 83 (nel tratto tra venere dei marsi e gioia dei marsi), nel comune di pescina. il fronte di scavo (fig. 3) interessa una successione costituita prevalentemente da depositi alluvionali quaternari (fig. 4). la porzione superiore della parete è costituita da materiale di riporto, connesso alla coltivazione della cava, non rilevante ai fini del presente studio. 4.1.1 stratigrafia al tetto della successione sedimentaria, si trova la copertura colluviale olocenica (unità 1 in fig. 4); si tratta di depositi di spessore pari a circa 2 m, matrice sostenuti, composti da limi e limi sabbiosi scuri con ghiaie costituite da clasti da centimetrici a pluricentimetrici. all’interno di quest’unità sono stati rinvenuti frammenti ceramici di impasto, fluitati, riferibili genericamente all’eneolitico–età del bronzo (3000-1500 anni a.c.). sono composti da materiale argilloso, di colore aranciato esternamente e grigio scuro nelle parti interne, con inclusi di calcare e minerali femici. la presenza di spigoli vivi fa dedurre un trasporto piuttosto breve. in quest’unità è stato prelevato un campione di materiale organico, la cui età radiocarbonio prodotta dal laboratorio, 3135±30 bp, calibrata a 2 sigma ha fornito 14661372 a.c. (codice laboratorio: poz-16619). subito al di sotto del colluvio, l’unità 2 (fig. 4), con spessore di 50 cm, è costituita da ghiaie in matrice sabbioso-siltosa scura. non sono stati riscontrati elementi diagnostici per definirne l’ambiente deposizionale. l’unità 2 poggia in discordanza sull’unità sottostante, di seguito descritta. l’unità 3 (fig. 4) è stata suddivisa in 4 sottounità: si tratta di differenti facies appartenenti ad un contesto deposizionale di ambiente alluvionale prossimo alla sponda lacustre. l’unità 3a (fig. 4), con spessore di circa 40 cm, è costituita da ghiaie grossolane arrotondate in abbondante matrice sabbioso-siltosa di colore grigio chiaro; i clasti sono matricesostenuti. l’unità 3c, in contatto discordante sulla sottostante unità 3d (figg. 4 e 5), ha una geometria lentiforme con spessore decrescente dai 40 ai 20 cm in direzione della faglia principale (f1). i depositi sono costituiti da silt sabbioso e da due livelli centimetrici di sabbie fini. considerando l’originaria deposizione, alluvionale ma in prossimità della sponda lacustre, la granulometria suggerisce che essi rappresentino il risultato di rielaborazione dei sedimenti in ambiente di spiaggia. tale interpretazione sembra anche corroborata dalla tendenza alla rastremazione dell’unità verso est, per cui 386 m. saroli et al. 387 fig. 2 settore orientale del bacino del fucino: aerofotogramma dal volo italia ’88-’89 alla scala 1:70.000. sono evidenziate le strutture tettoniche principali. il riquadro indica l’area di studio, gli asterischi indicano i siti. aerial view (“volo italia” 1988-89; 1:70,000 scale) of the eastern fucino basin. the main tectonic features have been indicated. the square defines the investigated area while the asterisks indicate the investigated sites. fig. 3. cava con fronte di scavo 1 (fs1 nel testo): evidenziati i contatti tra substrato calcareo, il colluvio e le ghiaie lacustri. quarry wall fs1: the contacts between the different stratigraphic units have been indicated. nuovi dati paleosismologici ... 388 fig. 4. riproduzione grafica e fotomosaico del fronte di scavo 1. unità 1: copertura colluviale olocenica costituita da depositi di spessore pari a circa 2 m, matrice sostenuti, composti da limi e limi sabbiosi scuri con ghiaie. unità 2: ghiaie in matrice sabbiosolimosa scura. unità 3a: ghiaie grossolane arrotondate in abbondante matrice sabbioso-limosa grigio chiaro con spessore di circa 40 cm. unità 3b: ghiaie in matrice sabbiosa con spessore variabile dai 20 ai 50 cm (cuneo colluviale). unità 3c: limo sabbioso con spessore variabile 40 ai 20 cm. unità 3d: ghiaie centimetriche in matrice sabbioso-limosa debolmente cementate con spessore di 25 cm. unità 4: ghiaie con ciottoli arrotondati in matrice limoso-sabbiosa scarsamente cementate, clastosostenute e caotiche. quarry wall log and photomosaic of the quarry wall fs1. unit 1: holocene darkish colluvial silts and sandy silts with gravel. unit 2: gravel in sandy-silty darkish matrix. unit 3a: coarse rounded pebbles in abundant light gray sandy-silty matrix. unit 3b: gravel in sandy matrix (colluvial wedge). unit 3c: sandy silt. unit 3d: slightly cemented sandy-silty gravel. unit 4: slightly cemented rounded gravel with sandy-silty matrix, massive and clast-supported. m. saroli et al. è ipotizzabile che la sedimentazione sia legata ad una fase di stazionamento lacustre prossimo al sito indagato. in rapporto stratigrafico concordante con l’unità 3c al tetto e discordante con la 3d al letto, l’unità 3b (fig. 4) è composta di ghiaie in matrice sabbiosa. lo spessore del deposito aumenta in direzione della faglia principale (f1), in corrispondenza della quale raggiunge i 50 cm. le caratteristiche geometriche dei limiti stratigrafici del tetto e della base dell’unità 3b e l’aspetto massivo tipico della deposizione colluviale inducono ad ipotizzare che si tratti di un “cuneo colluviale”, ovvero di un deposito alimentato da una adiacente scarpata di faglia (es. mccalpin, 1996). al di sotto del colluvio citato si trova l’unità 3d (fig. 4), costituita di ghiaie centimetriche in matrice sabbioso-siltosa; le ghiaie presentano debole cementazione carbonatica riconducibile a processi di circolazione idrica secondaria. sono inoltre presenti evidenti tracce di ossidazione in aree di forma lenticolare in sezione, anch’esse riconducibili ai medesimi processi. l’unità ha uno spessore di circa 25 cm. l’unità 4 (fig. 4), affiorante per circa 1.5 m di altezza, è composta di ghiaie con ciottoli arrotondati (diametro da 1 a 30 cm) con scarsa matrice siltoso-sabbiosa; presenta limitata cementazione ed una struttura clasto-sostenuta e caotica. questi aspetti fanno ipotizzare che l’originario deposito alluvionale sia stato rielaborato nell’ambiente lacustre prossimo alla linea di riva. e’ evidente un aumento della granulometria verso l’alto stratigrafico. 4.1.2 tettonica la parete è interessata da due piani di taglio: f1 nella parte orientale dell’affioramento e f2 nel settore più occidentale (fig. 4). f1 interessa tutta la successione e la limita verso est, ponendola in contatto con il substrato carbonatico (figg. 4 e 6). le unità alluvionali e colluviali appaiono intensamente deformate a ridosso di f1 e trascinate lungo il piano di faglia (fig. 6). f2 interessa le unità 2, 3 e 4 (fig. 4) per un’altezza di circa 1 m ed un rigetto piuttosto esiguo (10-20 cm). ipotizzando che la deposizione dell’unità 4 sia da riferirsi – per quota e in confronto ai livelli lacustri ricostruiti da giraudi (1999a) – al tardiglaciale e che essa sia correlabile con la piattaforma di abrasione lacustre che si trova al letto della faglia f1, l’entità della dislocazione che interessa tale unità potrebbe essere valutata nell’ordine dei 5 m. nella parete sono stati individuati almeno 3 eventi di dislocazione di età successiva alla deposizione dell’unità 3d. al più antico dei tre (e3) potrebbe essere riferibile la formazione del cuneo colluviale (unità 3b in fig. 4). come sopra 389 fig. 5. contatto tra l’unità 3c (sabbia) e l’unità 3d (ghiaie). stratigraphic contact between unit 3c (sand) and unit 3d (gravel). fig. 6. dettaglio della zona di faglia che pone a contatto il substrato carbonatico con le unità lacustri, alluvionali e colluviali. si noti l’intensa deformazione dei depositi trascinati verso l’alto dal movimento normale della faglia. view of the fault zone placing the carbonate substratum in contact with the lacustrine, alluvial and colluvial deposits. the intense deformation of the deposits along the fault zone is visible. nuovi dati paleosismologici ... accennato, le caratteristiche sedimentologiche dell’unità suggeriscono un’origine connessa all’erosione della adiacente scarpata di faglia formata a seguito del movimento della faglia f1. il secondo evento (e2), rappresentato dalla dislocazione legata alla faglia f2, è sicuramente posteriore alla deposizione dell’unità 3a e precedente alla deposizione dell’unità 1. la base dell’unità 2 è dislocata di 20 cm (fig. 4). l’assenza di dislocazione al tetto dell’unità 2 può essere imputata ad erosione successiva al movimento della faglia. per quanto concerne l’ultimo evento (o insieme di eventi) e1, ad esso è attribuibile la dislocazione dell’intera successione lungo il piano di faglia f1. tale dislocazione è sicuramente posteriore alla deposizione dell’unità colluviale 1, contenente materiale archeologico, come evidenziato dalla deformazione di questi depositi in prossimità del contatto con la faglia (fig. 6). in sintesi gli eventi di dislocazione che hanno interessato questa successione stratigrafica sono evidenziati, dal più antico: • e3: dalla deposizione del cuneo colluviale (unità 3b); • e2: dalla dislocazione dei depositi delle unità 2, 3 e 4; • e1: dalla fagliazione dell’intera successione sedimentaria, definita dall’intensa deformazione nei depositi alluvionali in prossimità della faglia (fig. 6) e dal trascinamento del deposito lacustre riferibile all’unità 3c lungo il piano di faglia. 4.2 fronte di scavo 2 (fs2) questa parete di scavo (l = 10 m; h = 3 m) è orientata circa e-o. si trova all’interno di una cava dismessa, a quota 690 m, anch’essa ubicata lungo la ss83 nel tratto tra venere e gioia dei marsi, circa 500 m a s del sito precedentemente descritto. anche in questo caso la successione sedimentaria è delimitata a e dal piano di faglia, contro cui le varie unità stratigrafiche terminano bruscamente (fig. 7). 4.2.1 stratigrafia al tetto dell’affioramento, l’unità 1, esposta per un’altezza pari a circa 40 cm, consiste di materiali di riporto nel settore più prossimo alla faglia principale, a e, e depositi detritico–colluviali rimaneggiati dalla lavorazione agricola attuale e subattuale (fig. 7), nel settore più occidentale. l’unità 2 (fig. 7), sottostante, è presente solo nel settore occidentale della parete, rastremandosi a e. si tratta di silt sabbioso scuro con ghiaia da media a fine (ø � 5 cm), con clasti calcarei a spigoli vivi. la matrice sabbiosa diventa preponderante nella “lente” individuabile nella parte sommitale dell’unità (2a in fig. 7). questo corpo lenticolare, che presenta parti a prevalente composizione argillosa di colore giallo-arancio, con screziature nerastre (campioni: co-1, co-2 in fig. 7; fig. 8) potrebbe rappresentare il riempimento di una fossa utilizzata per la cottura di materiali ceramici, riferibile (sulla base delle determinazioni sui frammenti ceramici rinvenuti) ad un insediamento eneolitico. alle attività legate alla fossa di cottura sono attribuibili i frammenti di concotto (fig. 8), vale a dire nuclei argillosi a colorazione rossastra la cui formazione è imputabile ad un processo di cottura indiretta o di surriscaldamento. nella zona più orientale di affioramento di quest’unità, si rinvengono due pietre calcaree di grandi dimensioni (ø > 30 cm), anomale rispetto al quadro stratigrafico e sedimentologico locale. esse sono probabilmente connesse al deposito archeologico sopra descritto. nel settore più occidentale del fronte di scavo, all’interno dell’unità 2, sono stati rinvenuti alcuni frammenti ceramici: • campione c1: frammento ceramico a superficie modellata con solchi. composizione argillosa, di colore aranciato e grigio, con inclusi in calcare e minerali femici. attribuibile a circa 3000-1500 anni a.c. (eneolitico – età del bronzo); • campione c2: ansa in ceramica di impasto leggermente lucidata esternamente (fig. 9); attribuibile all’eneolitico (3000-2000 anni a.c.); • campione c3: scheggia di materiale di impasto. la superficie di letto dell’unità 2 rappresenta il limite dello scavo realizzato in epoca preistorica all’interno della sottostante unità 3. l’unità 3 (fig. 7), di origine colluviale, è costituita da ghiaie supportate da una matrice sabbiosa di colore scuro. i clasti sono angolari o subangolari (ø max = 20 cm). la potenza del deposito è variabile dai 50 cm a 1 m. l’unità 4 (fig. 7) è presente solo a ridosso del piano di faglia, nel settore orientale della parete. si tratta di ghiaia in matrice sabbiosa di colore marrone chiaro, a tratti clasto-sostenuta, a tratti matrice-sostenuta, di natura colluviale. i clasti calcarei sono angolosi e di dimensioni dell’ordine della decina di cm (ø medio � 10 cm). l’unità presenta spessore decrescente allontanandosi dalla faglia e si chiude a circa 3 m da essa (spessore massimo = 40 cm). verso est l’unità è troncata bruscamente dalla faglia ed è separata da quest’ultima da uno spessore di 5-10 cm di ghiaie trascinate ed appartenenti all’unità 5 sottostante (fig. 7). le caratteristiche sedimentologiche e la diminuzione di spessore verso ovest conducono ad interpretare questa unità come il prodotto di sedimentazione dalla scarpata di faglia (i.e., “cuneo colluviale” sensu mccalpin, 1996). per quel che concerne l’unità 5 (fig. 7), su cui poggiano in contatto discordante le soprastanti unità, essa è stata suddivisa in due sub-unità sovrapposte con caratteristiche litologiche leggermente difformi. la sub-unità 5a, con spessore di 50 cm, è costituita da ghiaie con ciottoli calcarei (ø max = 25 cm) da sub-angolosi a sub-arrotondati immersi in una matrice calcarea composta da sabbia grossolana e ghiaia fine. l’unità si chiude sul piano di faglia che definisce il limite orientale dell’affioramento. la sub-unità 5b, sottostante, è invece composta da ghiaia con ciottoli calcarei di granulometria minore (ø max = 10 cm), da sub-arrotondati ad arrotondati, in matrice calcarea sabbiosa e ghiaiosa fine. la parte affiorante di questa unità, potente circa 50 cm, presenta a tratti evidente stratificazione piano parallela. 4.2.2 tettonica la successione descritta è interessata da numerosi piani di taglio e verso est termina contro la faglia f1, al letto della quale affiora il substrato carbonatico (fig. 7). nel settore occidentale della parete sono stati individuati alcuni piani di taglio minori con cinematica normale (sistema f2), che dislocano esclusivamente l’unità 5 (fig. 7). il piano f1 disloca l’intera successione ribassandola verso ovest, ad eccezione dell’unità 1. il m. saroli et al.390 fig. 7. riproduzione grafica e fotomosaico del fronte di scavo 2. unità 1: materiali di riporto nel settore più prossimo alla faglia principale e depositi detritico–colluviali rimaneggiati dalla lavorazione agricola attuale e sub-attuale. unità 2: limo sabbioso scuro con ghiaia da media a fine; presenta parti a prevalente composizione argillosa di colore giallo-arancio, con screziature nerastre. unità 3: ghiaie supportate da una matrice sabbiosa di colore scuro di origine colluviale, con spessore variabile dai 50 cm a 1 m. unità 4: ghiaia in matrice sabbiosa di colore marrone chiaro, a tratti clasto-sostenuta, a tratti matrice-sostenuta, di natura colluviale (cuneo colluviale). unità 5: è stata suddivisa in due sub-unità sovrapposte con caratteristiche leggermente difformi. sub-unità 5a, con spessore di 50 cm costituita da ghiaie con ciottoli calcarei da sub-angolosi a subarrotondati immersi in una matrice calcarea composta da sabbia grossolana e ghiaia fine; sub-unità 5b, ghiaia con ciottoli calcarei da sub-arrotondati ad arrotondati, in matrice calcarea sabbiosa e ghiaiosa fine con evidenze di stratificazione. quarry wall log and photomosaic of the quarry wall fs2. unit 1: reworked materials and colluvial deposits affected by the presentrecent agricultural works. unit 2: darkish sandy silt with medium-fine gravel, displaying portions characterised by yellowish-orange clayey with blackish levels. unit 3: colluvial gravel supported by darkish sandy matrix. unit 4: colluvial gravel with light-brown sandy matrix; showing both a matrix-supported and a clast-supported structure (colluvial wedge). unit 5: made of two different sub-units: sub-unit 5a, gravel with carbonate sub-angular to sub-rounded pebbles in coarse sandy-fine gravelly carbonate matrix; sub-unit 5b, layered sub-rounded to rounded carbonate gravel in sandy-fine gravelly carbonate matrix. nuovi dati paleosismologici ... 391 rigetto minimo stimato è di 2 m circa, calcolato misurando la differenza compresa tra il tetto della sub-unità 5b e il punto fino al quale essa è trascinata lungo il piano di faglia. nel complesso, gli eventi di dislocazione rilevati in questo fronte di scavo sono tre, tutti posteriori alla deposizione della sub-unità 5a. l’evento più antico (e3) è evidente nella dislocazione della sub-unità 5 lungo i piani di taglio (f2) presenti a ridosso del piano di faglia principale (fig. 7). la sub-unità 5a è stata erosa nel settore sollevato, al letto dei piani di taglio f2, prima della deposizione del cuneo colluviale (unità 4). ciò implica la dislocazione e la successiva erosione di 5a. l’origine dell’unità 4 (fig. 7) per erosione di una scarpata di faglia cosismica (f1) definisce un secondo evento di dislocazione (e2). il cuneo colluviale (unità 4) è in contatto discordante con l’unità 5 e da essa è separato da una superficie di erosione. tale superficie consente di differenziare gli eventi di dislocazione e2 e e3. il più recente evento di dislocazione (e1) ha interessato i depositi lungo la faglia principale (f2). esso è successivo alla deposizione delle unità 3 e 4, come evidenziato dal fatto che queste ultime sono in contatto laterale verso il piano di faglia con uno spessore pluricentimetrico di ghiaie trascinate dell’unità 5. l’evento è precedente alla deposizione dell’unità 1, che tronca la parte trascinata dell’unità 4 e che non risulta dislocata dall’attività della faglia (fig. 7). l’unità 2, contenente i frammenti ceramici eneolitici, non si rapporta al piano di faglia; è pertanto impossibile chiarire se la faglia f1 si sia attivata o meno dopo la sua deposizione. l’assenza di unità al letto della faglia non consente di effettuare una più dettagliata scansione dell’attività per singoli eventi di dislocazione. nonostante manchino vincoli cronologici di tipo radiometrico relativi all’unità 3, la correlazione stratigrafica, sulla base delle caratteristiche litologiche, tra questa e il colluvio del fronte di scavo 1 (unità 1 in fig. 4) contenente frammenti ceramici, cronologicamente compatibili con il livello di frequentazione (unità 2) scavato nell’unità 3, consentono di riferire con buona probabilità l’evento e1 ad un periodo successivo all’ eneolitico (2000-3000 a.c.). in sintesi gli eventi che hanno interessato questa successione sono, dal più antico: • e3: dislocazione delle ghiaie dell’unità 5 ed erosione della porzione superiore 5a; • e2: deposizione del cuneo colluviale (unità 4) per erosione di una scarpata cosismica; • e1: dislocazione dell’unità 3, evidenziata dal fatto che essa si relaziona con il piano di faglia f1 tramite uno spessore di depositi trascinati dalle unità sottostanti. 5. considerazioni finali sul contesto crono-stratigrafico dei paleoeventi rilevati le unità ghiaioso-sabbiose (unità 3 e 4 in fs1; unità 5 in fs2) presenti nei fronti di scavo analizzati al di sotto dei colluvi sono da considerarsi, in base alla letteratura disponibile (giraudi, 1988; 1999a) e alle evidenze sedimentologiche, deposte in ambiente lacustre prossimale. la sedimentazione delle menzionate unità sarebbe riferibile ad una fase di alto stazionamento del lago posteriore all’ultimo massimo glaciale (probabilmente avvenuta intorno a 14-15 ka b.p.; giraudi, 1988). all’episodio erosivo conseguente all’abbassamento del livello del lago sarebbero riferibili, invece, le superfici di erosione al tetto delle ghiaie delle unità 3 (fs1) e 5 (fs2). considerando 1) che la piattaforma di abrasione lacustre scolpita sui calcari al letto della faglia, modellata nel corso dell’alto stazionamento lacustre durante l’lgm (es. giraudi, 1988), rappresenta verosimilmente anche la quota dell’alto stazionamento del tardiglaciale (giraudi, 1999a) e 2) che le unità sabbioso-siltose sono riferibili a rielaborazione e rideposizione di precedenti sedimenti alluvionali in prossimità della sponda lacustre e che pertanto le unità ghiaiose rappresentano comunque sedimenti deposti nell’ambiente lacustre dell’alto stazionamento del tardiglaciale, non essendo noti livelli lacustri più recenti alle quote dell’area indagata, la differenza di quota tra la superficie di abrasione al letto delle faglie in fs1 e fs2 e quella di erosione sui depositi al tetto delle stesse può fornire un’indicazione di massima sull’entità del rigetto cumulato successivamente al tardiglaciale. tale rigetto è valutabile in max. 5 m per fs1 e in max. 2 m per fs2. attribuendo alle ghiaie un’età non più recente di 14-15 ka (in base alla letteratura disponibile; si veda ad es. giraudi, 1999a), è possibile determinare un rateo di movimento non superiore a 0.35 mm/a per la faglia f1 di fs1 ed un rateo non superiore a 0.14 mm/a per la faglia f1 di fs2. per quanto riguarda l’inquadramento cronologico degli eventi di dislocazione, in base alla bibliografia disponibile (es. galadini e galli, 1999), gli eventi e2 ed e3 individuati sui due fronti di scavo potrebbero essere assimilati a due dei tre più antichi eventi olocenici noti fig. 8. campione di argilla cotta (co1-co2 in figura 7). sample of potter’s clay from the pit-fire of fs2 (unit 2 in fig. 7). m. saroli et al.392 in bibliografia, avvenuti tra 5 e 10 ka a.c. il più recente di tali eventi (5.979-5.576 a.c.) viene fatto coincidere con la causa dei crolli registrati nella grotta continenza (giraudi, 1999b). tali crolli sono attribuiti alla cultura di ripoli (5.5-4.2 ka a.c.) da radmilli (1981). e2 ed e3 potrebbero, tuttavia, rappresentare la traccia di eventi occorsi nel pleistocene superiore finale dopo il tardiglaciale. a questo proposito si ricorda che le informazioni paleosismologiche relative a tale contesto cronologico sono, finora, piuttosto lacunose. per quel che concerne i reperti archeologici rinvenuti nelle unità più recenti delle successioni studiate (unità 1 in fs1; unità 2 in fs2), va ricordato che essi presentano caratteristiche assimilabili a quelli trovati nelle campagne di scavo effettuate nel sito di le coste (radi, 1996, 2000; radi e ventura, 1994; radi et al., 2001), ubicato all’interno di una cava posta 500 m più a nord di fs1. i frammenti ceramici in fs1 e fs2 e le ceramiche dell’unità eneolitica rinvenuta nel sito di le coste sono affini: in particolare, il campione c2 in fs2 (fig. 9) sembra presentare caratteri del tutto comparabili a quelli delle ceramiche fini e semifini dello strato 2 del sito di le coste. inoltre, dato il quadro archeologico e le caratteristiche litologiche delle unità definite nei capitoli precedenti, si può ragionevolmente ipotizzare che la fossa di cottura individuata in fs2 e i materiali ad essa riferibili siano correlabili al deposito eneolitico della citata località. infine, i reperti archeologici rinvenuti in fs1 e fs2 consentono di riferire le unità che li contengono ad un ambito cronologico che comprende il tardo neolitico–età del bronzo (5.000–1.500 a.c.). la datazione radiometrica effettuata su un campione di materiale organico appartenente all’unità 1 di fs1 (1466-1372 b.c., età calibrata a 2 sigma), è compatibile con le indicazioni archeologiche. ciò definisce un vincolo cronologico per l’evento più recente. infatti, le rotture sui piani di faglia principali (e1 in fs1; e1 in fs2) potrebbero essere fatte coincidere con l’evento già attribuito nei lavori precedenti all’intervallo 15001300 a.c. (galadini et al., 1997a; galadini e galli, 1999 e bibliografia) (evento dell’età del bronzo) e/o, in considerazione dell’entità della dislocazione osservabile nell’unità 1 in fs1, al penultimo evento olocenico risalente all’alto medioevo (426–782 d.c., età 14c cal.; galadini e galli, 1999). a questo va aggiunto che probabilmente l’evento del 1915 ha comportato un’ulteriore dislocazione delle successioni affioranti, sebbene essa non sia direttamente rilevabile per mancanza di depositi tanto recenti conservati a ridosso della scarpata. 6. conclusioni l’analisi di affioramenti in due cave poste alla base dei rilievi che bordano il fianco orientale del bacino del fucino ha permesso di incrementare le conoscenze paleosismologiche sull’area fucense. i fronti di scavo analizzati sono posti in corrispondenza di una scarpata di faglia che costituisce parte dell’espressione superficiale del sistema di faglie dirette attivo dal pliocene e costituito dalla faglia s.benedetto dei marsigioia dei marsi e dalla faglia della s.s. marsicana. l’effetto della dislocazione osservata nelle pareti di scavo è il prodotto di movimenti ripetuti lungo uno dei piani di faglia del sistema s.benedetto dei marsi-gioia dei marsi. le analisi paleosismologiche hanno beneficiato, per l’inquadramento cronologico delle unità dislocate, di determinazioni archeologiche su frammenti ceramici e correlazioni stratigrafiche, sostanziate da una datazione radiometrica. le informazioni cronologiche hanno permesso di attribuire all’olocene gli eventi di fagliazione individuati. gli eventi di dislocazione sono da considerarsi tutti più recenti delle formazioni ghiaiose riferibili ad una fase di alto stazionamento del lago, posteriore all’ultimo massimo glaciale (probabilmente 14-15 ka b.p.; giraudi, 1988), che costituiscono la porzione basale di entrambe le successioni stratigrafiche. sul primo fronte di scavo indagato (fs1; fig. 4) sono registrati almeno tre eventi di dislocazione, correlabili a movimenti con cinematica normale avvenuti lungo il piano di faglia principale. i due eventi più antichi (e3, e2 in fig. 4) sono sicuramente posteriori alla deposizione delle ghiaie lacustri, di età prossima a 14-15 ka b.p., e probabilmente al deposito colluviale contenente i reperti eneolitici e dell’età del bronzo (fino a 3.000 b.p.) e il campione datato radiometricamente. tali eventi si collocano temporalmente tra 15.000 e 3.000 anni b.p. l’evento più recente (o serie di eventi) e1 è riconoscibile lungo il piano di faglia principale (f1 in fig. 4) ed è posteriore alla deposizione del colluvio (unità 1); pertanto esso sarebbe successivo a 1466-1372 cal. a.c. la mancanza di unità correlabili al letto e al tetto della faglia f1 non permette di fornire una scansione più dettagliata degli eventi e di valutare i rigetti reali. sul secondo fronte di scavo (fs2; fig. 7), l’analisi paleosismologica ha evidenziato l’occorrenza di tre eventi di dislocazione, riconducibili a movimenti con cinematica normale della faglia principale che borda verso est la successione di unità tardopleistocenicheoloceniche, ponendola in contatto con il substrato carbonatico. i due eventi più antichi (e3, e2 in fig. 7) sono posteriori alla deposizione delle ghiaie lacustri (unità 5) e precedenti al deposito colluviale contenente i reperti archeologici (unità 2). anche in questo caso tali eventi di dislocazione vanno riferiti ad un ambito cronologico fig. 9. frammento ceramico lucidato (c2 in fs2, fig. 7). pottery shard (c2 in fs2, fig. 7). nuovi dati paleosismologici ... 393 compreso tra 15.000 e 3.000 anni b.p. per quel che concerne l’evento più recente (e1 in fig. 7), riconoscibile sul piano di faglia f1 in fs2, esso non è completamente vincolabile da un punto di vista cronologico. in ogni caso, la presenza di un’unità attestante la frequentazione del sito, con sedimenti che riempiono una fossa scavata nel colluvio dell’unità 2, suggerisce, per comparazione con fs1, che e1 sia da riferire ad un periodo posteriore all’eneolitico. il rigetto approssimativo lungo i piani di faglia principali dei due affioramenti sarebbe non superiore a 5 m per il primo fronte di scavo e a 2 m per il secondo. attribuendo all’ultima fase di erosione delle ghiaie lacustri un’età intorno a 15.000–14.000 anni b.p. (giraudi, 1999a), è possibile stimare un rateo di movimento non superiore a circa 0.35 mm/a per la faglia f1 di fs1 e a 0.14 mm/a per la faglia f1 di fs2. nel complesso, i dati ottenuti dal presente lavoro confermano alcune conclusioni delle precedenti indagini paleosismologiche. l’insieme dei dati qui riportati deve considerarsi, pertanto, come un incremento al già cospicuo dataset paleosismologico disponibile per la piana del fucino, in un segmento di faglia contermine ad altri precedentemente indagati. l’ulteriore incremento delle conoscenze paleosismologiche, via via acquisite nel corso di quasi un decennio, contribuisce ancora di più a renderle base irrinunciabile per la caratterizzazione del comportamento sismogenetico della sorgente del terremoto del 1915. bibliografia bosi c., caiazzo c., cinque a., messina p., 1996 le superfici relitte nell’area fucense (appennino centrale) ed il loro possibile significato nella ricostruzione della evoluzione geologica. il quaternario, 9 (1), 381-386. galadini f., galli p., 1996 paleoseismology related to deformed archaeological remains in the fucino plain, implications for subrecent seismicity in central italy. ann. geofis. 39, 925–940. galadini f., galli p., 1999 the holocene paleoearthquakes on the 1915 avezzano earthquake faults (central italy): implications for active tectonics in the central apennines. tectonophysics, 308, 143-170. galadini f., galli p., 2000 active tectonics in the central apennines (italy)input data for seismic hazard assesment. natural hazards, 22, 225 270. galadini f., galli p., giraudi c., 1997a paleosismologia della piana del fucino (italia centrale). il quaternario, 10 (1), 27-64. galadini f., galli p., giraudi c., 1997b geological investigations of italian earthquakes: new paleosismological data from the fucino plain (central italy). j. geodynamics, nos 1-4, 87-103. galadini f., galli p., giraudi c., molin d., 1995 il terremoto del 1915 e la sismicità dela piana del fucino (italia centrale). boll. soc. geol. it., 114, 635-663. galadini f., galli p., molin d., 1998 caratteristiche della sismicità della zona del fucino (italia centrale): implicazioni sismotettoniche. il quaternario, 11, 179-189. galadini f., messina p., 1994 plio-quaternary tectonics of the fucino basin and surroundings areas (central italy). giornale di geologia, serie 3a, vol. 56, n.2, 73-99. giraudi c., 1988 evoluzione geologica della piana del fucino (abruzzo) negli ultimi 30.000 anni. il quaternario, 1 (2), 131-159. giraudi c., 1995 i detriti di versante ai margini della piana del fucino (italia centrale): significato paleoclimatico ed impatto antropico. il quaternario, 8 (1), 203-210. giraudi c., 1999a. evoluzione geologica tardo-pleistocenica ed olocenica della piana del fucino e dei versanti adiacenti: analisi di nuovi dati stratigrafici e radiometrici e ricostruzione delle variazioni ambientali. in s. castenetto e f. galadini (a cura di): “13 gennaio 1915, il terremoto nella marsica”, istituto poligrafico e zecca dello stato, roma, 183-197. giraudi c., 1999b chronological assesment and paleoenvironmental implications of the speleothems from the caves of fucino plain (abruzzo, central italy) . il quaternario, 12 (1), 79-84. gruppo di lavoro cpti, 2004 catalogo parametrico dei terremoti italiani, versione 2004 (cpti04), ingv, bologna. http://emidius.mi.ingv.it/cpti04/ mccalpin j. 1996 paleoseimology. accademic press ldt., pp. 588, london. michetti a.m., brunamonte f., serva l., vittori e., 1996 trench investigations of the 1915 fucino earthquake fault scarps (abruzzo, central italy): geological evidence of large historical events. j. geophys. res. 101, 5961-5936 molin d., galadini f., galli p., mucci l., rossi a. 1999 terremoto del fucino del 13 gennaio 1915. studio macrosismico. in s. castenetto, f. galadini (a cura di): “13 gennaio 1915, il terremoto nella marsica”, istituto poligrafico e zecca dello stato, roma, 321-340. radi g., 1996 le coste. stazione dell'eneolitico e della media età del bronzo nel fucino (pescina, l'aquila), origini, vol. xix, pp. 415-445. radi g., 2000 nuovo aspetto dell'eneolitico individuato nel fucino a le coste (ortucchio aq), recenti acquisizioni, problemi e prospettive della ricerca sull'eneolitico dell'italia centrale, vol. 1, pp. 293307, arcevia radi g., berton a., castiglioni e., rottoli m., 2001 le coste, stazione dell’età dei metalli. il fucino e le aree limitrofe nell’antichità, celano, vol.1, 110125. radi g., ventura o. ,1994 nuovo sito di ceramica a squame nel fucino, r.s.p., vol. xlvi, 1, 177-190. radmilli a.m., 1981 storia dell’abruzzo dalle origini all’età del bronzo. ed. giardini, pisa, 451pp. serva l., blumetti a.m. & michetti a.m. (1986) gli effetti sul terreno del terremoto del fucino (13 gennaio 1915); tentativo di interpretazione della evoluzione tettonica recente di alcune strutture. mem. soc. geol. it., 35, 893-907. ms. ricevuto il 19 febbraio 2008 testo definitivo ricevuto il 10 giugno 2008 ms. received: february 19, 2008 final text received: june 10, 2008 m. saroli et al.394 imp.martino& aspetti morfotettonici dell’evoluzione geomorfologica della valle del melandro (appennino campano-lucano) claudio martino 1 & marcello schiattarella 1 1 dipartimento di scienze geologiche, università degli studi della basilicata, potenza riassunto: c. martino & m. schiattarella, aspetti morfotettonici dell’evoluzione geomorfologica della valle del melandro (appennino campano-lucano). (it issn 0394-3356, 2006). la valle del melandro è una depressione tettonica che si sviluppa in direzione no-se lungo la zona assiale della catena sud-appenninica. è colmata da sedimenti quaternari che giacciono su due grandi unità tettoniche sovrapposte: l’unità dei monti della maddalena, costituita prevalentemente da carbonati meso-cenozoici di mare basso, a tetto e le unità lagonegresi, formate da successioni pelagiche mesozoico-terziarie, a letto. tali caratteri rendono l’area particolarmente adatta alla stima dei tassi di sollevamento: sono infatti presenti successioni sufficientemente resistenti all’erosione da conservare diversi elementi morfotettonici relativamente antichi, con particolare riferimento alle superfici erosionali sospese, sufficientemente vincolabili cronologicamente grazie alla presenza di successioni plioceniche e pleistoceniche. i tassi di sollevamento sono stati calcolati usando la differenza di quota tra superfici erosionali ed il livello di base assoluto (livello del mare) e locale (talweg attuale). sono stati inoltre stimati i tassi di sollevamento per intervalli temporali compresi tra due fasi di erosione consecutive (sollevamento “partizionato”), considerando la differenza di quota tra un dato ordine di superfici e quello immediatamente più giovane. nella valle e sui rilievi contigui sono stati distinti quattro ordini di superfici erosionali con peculiari caratteristiche morfologiche, che differiscono tra la dorsale carbonatica in sinistra orografica ed il fianco opposto in terreni lagonegresi. l’ordine più antico (s1) corrisponde alla paleosuperficie auctt. di età altopliocenica, poichè rasa depositi marini del pliocene inferiore-medio affioranti sui monti della maddalena. morfologicamente incastrate nella superficie sommitale appaiono le superfici s2, s3 ed s4. le superfici s3 rasano il riempimento continentale del bacino della valle del melandro del pleistocene inferiore: ciò permette di attribuire tale ordine alla parte alta del pleistocene inferiore, al passaggio con il pleistocene medio. le superfici s2, interposte tra s1 e s3, sono conseguentemente attribuibili al pleistocene inferiore. infine, le superfici s4 sono databili al pleistocene superiore per correlazione morfostratigrafica su scala regionale. le superfici s1, modellate nel pliocene superiore, sono state tettonicamente sbloccate durante l’inizio del pleistocene inferiore, mentre quelle s2, che si sono formate prima della deposizione del riempimento continentale del bacino della valle del melandro, hanno iniziato a sollevarsi durante l’episodio tettonico regionale di età emiliana. i glacis erosionali s3, modellati dopo l’aggradazione del bacino ad opera dei depositi alluvionali, sono stati disattivati e sollevati al debutto del pleistocene medio, mentre i terrazzi erosionali (s4), morfologicamente incastrati nei precedenti, hanno subito un sollevamento durante il pleistocene superiore. i due fianchi del bacino presentano modalità di sollevamento differenti. nel corso del pleistocene inferiore, il versante in destra orografica si solleva più velocemente rispetto a quello opposto, mentre a partire dal pleistocene medio avviene il contrario. in generale, i tassi di sollevamento calcolati per l’intero bacino della valle del melandro hanno messo in evidenza un decremento dei valori tra il pleistocene inferiore e quello medio, considerando il sollevamento locale e “partizionato”, a differenza dei dati relativi al sollevamento regionale che descrivono un trend crescente a partire dall’inizio del pleistocene. la comparazione tra le quote dei relitti di superfici erosionali con il profilo longitudinale del fiume sele, a partire dal torrente pergola (affluente del fiume melandro, che fa appunto parte del sistema idrografico a recapito tirrenico del sele), ha permesso di ipotizzare una formazione in ambiente genetico fluviale delle superfici s3 ed s4 ben al di sopra del livello del mare. queste presentano, infatti, un andamento conforme a quello del profilo longitudinale del fiume sele. le superfici s1 ed s2 hanno, invece, un andamento molto regolare e prossimo alla orizzontalità, come possibile conseguenza di un modellamento in corrispondenza del livello del mare, geneticamente legato all’azione dell’abrasione marina. queste considerazioni permettono di operare una correzione alla stima dei tassi di sollevamento regionale per le superfici s3, sulla base della differenza di quota che intercorre tra tali superfici ed il paleo-livello di base relativo alla parte alta del pleistocene inferiore, impostato sui conglomerati di eboli. tale correzione modifica l’andamento del tasso di sollevamento regionale e lo rende congruente con i tassi di uplift locale e “partizionato”. abstract: c. martino & m. schiattarella, morphotectonics and quaternary geomorphological evolution of the melandro valley, southern apennines, italy. (it issn 0394-3356, 2006). the target of this study is to furnish new data on the morphotectonic setting of a key-area of the southern italian apennines, the valley of melandro river, by means of both geomorphological and structural analyses. further, a fruitful attempt of morphostratigraphic correlation of several orders of sub-horizontal land surfaces and flat summit landscapes with other similar geomorphic features on a regional scale has been done. the age attribution of such features to sufficiently constrained pliocene and pleistocene time intervals allowed the calculation of the regional and local uplift rates and the reconstruction of the morphotectonic history of the study area. the melandro river basin is a tectonic depression located in the axial zone of the south-apennines chain, a fold-and-thrust belt strongly uplifted and fragmented by neotectonics and therefore characterized by many quaternary longitudinal and transversal morphostructural depressions. the uplift rates have been estimated using geomorphological, stratigraphical and structural data. geomorphic data consist essentially of elevation values, ages and arrangement of erosional gently dipping land surfaces and other morphotectonic indicators. the morphostructural evolution of the melandro river basin is characterized by stages of uplift alternated with slack periods in which the erosional surfaces developed. in particular, four generations of land surfaces have been detected on the basis of both field survey and map analysis. the age of these surfaces have been defined on the basis of morphostratigraphic relationships with the pliocene and quaternary deposits. specifically, the oldest surface was sculptured also in the marine pliocene deposits whereas the intermediate surface cuts the continental lower pleistocene sediments filling the main depression. the youngest surface is late pleistocene in age, as verified for similar terraces in adjacent areas. the uplift rates have been calculated on the basis of the difference in height between the absolute (sea level) or local (present-day talweg) erosion base levels and the several generations of land surfaces. further, in this study we also calculated the stage (or partitioned) uplift on the basis of the difference in height between a given order of land surfaces and that immediately younger, aiming to consider the behaviour trend in specific time intervals. the trend of stage uplift is characterized by two increments: the first during the upper part of the early pleistocene and the second during the late pleistocene. new data permitted us to restore the palaeomorphology of the different land surfaces and, by comparing them with present-day longitudinal stream profiles, to formulate suitable hypotheses on the genetic environments of these ancient erosional flat landscapes. in particular, the older surfaces seem to be generated at the sea level by marine erosion, whereas the younger ones show a continental origin, maybe related to cold periods of the pleistocene, and were altered under warm-humid climatic conditions, as deduced from the presence of peculiar weathering fronts and as suggested by correlations with the global sea-level changes. parole chiave: geomorfologia strutturale, superfice erosionale, tasso di sollevamento, val melandro, appennino campano-lucano. keywords: structural geomorphology, land surface, uplift rate, melandro valley, southern apennines (italy). il quaternario italian journal of quaternary sciences 19(1), 2006 119-128 120 c. martino & m. schiattarella 1. introduzione negli ultimi anni viene registrato un sempre crescente interesse verso le problematiche relative alle velocità di sollevamento e alle conseguenti implicazioni sull’evoluzione geomorfologia di aree orogeniche. per l’appennino meridionale simili tematiche sono state affrontate, recentemente, con approcci multidisciplinari volti alla comparazione tra sollevamento e smantellamento erosivo (schiattarella et al., 2003, 2006; boenzi et al., 2004). la valle del melandro è una depressione tettonica che si sviluppa in direzione no-se lungo la “zona assiale” (sensu ortolani et al., 1992) della catena sudappenninica. è colmata da sedimenti quaternari che giacciono su due grandi unità tettoniche sovrapposte: l’unità dei monti della maddalena, costituita prevalentemente da carbonati meso-cenozoici di mare basso, a tetto e le unità lagonegresi, formate da successioni pelagiche mesozoico-terziarie, a letto. tali caratteri rendono l’area particolarmente adatta alla stima dei tassi di sollevamento: sono infatti presenti successioni stratigrafiche sufficientemente resistenti all’erosione da conservare diversi elementi morfotettonici relativamente antichi, con particolare riferimento alle superfici erosionali sospese, databili grazie alla presenza di successioni plioceniche e pleistoceniche. l’evoluzione geomorfologica della valle del melandro è stata fortemente condizionata da più fasi di sollevamento, peraltro caratterizzate da un differente comportamento dei due fianchi del bacino. infatti, nel corso del pleistocene inferiore, il versante in destra orografica si è sollevato più velocemente rispetto a quello opposto, mentre a partire dal pleistocene medio – è avvenuto il contrario. nella valle e sui rilievi contigui sono stati distinti quattro ordini di superfici erosionali con peculiari caratteristiche morfologiche, che differiscono tra i monti della maddalena in sinistra orografica ed il fianco opposto in terreni lagonegresi. tali elementi morfotettonici, datati grazie ai rapporti con i depositi plio-pleistocenici, sono stati utilizzati nella stima dei tassi di sollevamento. quest’ultimi sono stati calcolati usando la differenza di quota tra superfici erosionali ed il livello di base assoluto (livello del mare) e locale (talweg attuale). inoltre, sono stati stimati i tassi di sollevamento per intervalli temporali compresi tra due fasi erosive consecutive (tasso di sollevamento “partizionato” o stage uplift rate di schiattarella et al., 2006), considerando la differenza di quota tra un dato ordine di superficie e quello immediatamente più giovane. 2. inquadramento geologico e geomorfologico l’area investigata è una piccola porzione del prisma di accrezione sud-appenninico derivante dalla deformazione di diverse unità paleogeografiche ubicate lungo il margine passivo mesozoico della placca adriatica e della copertura ofiolitifera proveniente da un adiacente braccio dell’oceano tetideo (d’argenio et al., 1986; sgrosso, 1988; pescatore et al., 1999, tra gli altri). le differenti unità tettoniche sono sovrascorse l’una sull’altra con vergenza adriatica. da ovest verso est si riconoscono: i) le unità interne, che rappresentano un prisma di accrezione oligo-miocenico con blocchi di ofioliti, corredato da depositi sintettonici del miocene inferiore; ii) la piattaforma appenninica; iii) le unità lagonegresi, derivanti dalla deformazione del bacino omonimo; iv) le unità irpine, depositatesi in bacini satellite e di avanfossa nel miocene medio-superiore al di sopra delle unità lagonegresi deformate; v) la piattaforma apula. la deformazione delle differenti unità paleogeografiche è iniziata secondo alcuni autori nel miocene inferiore (d’argenio et al., 1986; patacca & scandone, 2001, tra gli altri) e per altri nell’oligocene superiore (pescatore et al., 1999) ed è proseguita con la migrazione di sovrascorrimenti, bacini di thrust-top ed avanfosse sino al pleistocene (pi e r i et al., 1997; patacca & scandone, 2001, tra gli altri). l’edificio appenninico così strutturato è stato ampiamente dislocato da faglie ad alto angolo, plio-quaternarie trascorrenti ed estensionali (schiattarella, 1998). il sollevamento dell’appennino meridionale è strettamente collegato alle fasi tettoniche plio-pleistoceniche avvenute all’interno del sistema mar tirreno – catena. nel pliocene medio si è sviluppata una importante fase tettonica (ortolani, 1978), marcata tra l’altro da una vistosa discordanza angolare nel bacino dell’ofanto (giannandrea, 2003). durante il pliocene superiore domina il fagliamento trascorrente (russo & schiattarella, 1992; ascione & cinque, 1995) con la formazione di alti e bassi strutturali secondo i meccanismi della trastensione e della traspressione (ortolani et al., 1992). in questo periodo ha luogo la subsidenza del bacino di vavilov (sartori, 1989) ed un modesto sollevamento del settore peritirrenico della catena accompagnato dalla formazione dei bacini del golfo di salerno, della piana del fiume garigliano e di quella del fiume volturno (brancaccio et al., 1991). i sollevamenti più significativi, però, iniziano con il pleistocene, in coincidenza di due importanti fasi parossistiche. la prima, sviluppatasi a partire dall’inizio del pleistocene inferiore, è caratterizzata da forti sollevamenti in catena e dalla contemporanea sedimentazione di imponenti serie clastiche continentali quali i conglomerati di auletta (ascione et al., 1992), i conglomerati di eboli (brancaccio et al., 1991) e i depositi del pergolamelandro (lippman provansal, 1987; santangelo, 1991) e marine (d’argenio et al., 1986; brancaccio et al., 1991). una seconda fase parossistica accompagna l’inizio del pleistocene medio con notevoli sollevamenti differenziali che hanno portato ad una disorganizzazione della rete idrografica con la formazione di diversi bacini intermontani lacustri quali, ad esempio, il vallo di diano e il bacino di acerno (d’argenio et al., 1986; brancaccio et al., 1991). durante gli intervalli freddi del pleistocene medio si assiste alla rapida evoluzione delle scarpate di faglia per recessione rettilineo-parallela lungo l’intera fascia peritirrenica (brancaccio et al., 1979) ed i detriti generati ingombrano le valli e colmano i bacini lacustri determinando gli imponenti accumuli clastici attualmente terrazzati e riconoscibili in tutti i bassi morfologici. nel periodo compreso tra le due fasi parossistiche registrate nel mar tirreno ha luogo la subsidenza del bacino dei marsili, a partire da 1.3 ma (sartori, 1989), mentre i fenomeni di uplift si propagano anche nei settori più esterni della catena, nella fossa bradanica e nell’avanpaese (westaway, 1993). in questo stesso periodo, una “fase” tettonica in catena, iniziata 1.2 ma, è responsabile del sollevamento delle superfici erosionali del pliocene superiore e pleistocene inferiore (schiattarella et al., 2003). durante il pleistocene superiore si assiste ad una sostanziale stabilità del settore peritirrenico, come testimoniato dai terrazzi tirreniani posti pochi metri sul livello del mare lungo tutta la costa (cosentino & gliozzi, 1988; bordoni & valensise, 1998; tra gli altri). in questo periodo si sollevano principalmente la zona assiale, il fronte della catena, la fossa bradanica e settori dell’avampaese (cosentino & gliozzi, 1988; westaway, 1993; bordoni & valensise, 1998; cucci & cinti, 1998; amato, 2000; schiattarella et al., 2003, 2006). la depressione tettonica della valle del melandro rappresenta uno dei diversi bacini intermontani pleistocenici dell’appennino meridionale (fig. 1). tra i bacini posti lungo la zona assiale della catena, è l’unico con depositi di età infrapleistocenica (lippman provansal, 121aspetti morfotettonici ... 1987), mentre gli altri (vallo di diano, alta val d’agri, bacino del mercure) sono non più antichi del pleistocene medio. bacini di età comparabile sono invece ubicati lungo il settore tirrenico della catena (bacino di auletta, area dei conglomerati di eboli). la valle del melandro è aggradata da depositi alluvionali del pleistocene inferiore (lippman provansal, 1987) distinti in tre unità litostratigrafiche separate da paleosuoli e superfici di erosione (giano & martino, 2003). tali depositi sono spianati da una superficie erosionale che si estende, seppure in modo frammentato, lungo tutto l’asse vallivo e si raccorda con i versanti dei rilievi adiacenti (martino, 2005). oltre alla superficie impostata sui depositi continentali del bacino, sono state riconosciute diverse superfici di spianamento sia sui monti delle maddalena, a quote superiori ai 1000 m, che sui monti che delimitano la valle ad oriente, tra gli 800-900 m e i 1100-1300 m (santangelo, 1991). fig. 1 carta geologica schematica del bacino del fiume melandro. geological sketch map of the melandro river basin. 122 3. analisi morfostrutturale i margini del bacino della valle del melandro sono contraddistinti da un andamento molto irregolare a causa di un’evoluzione tettonica polifasica (fig. 1). dall’analisi statistica delle mesofaglie rilevate in massima parte nel massiccio carbonatico dei monti della maddalena è stato possibile osservare una cinematica polifasica per tutte le principali famiglie di faglia (fig. 2). alcune faglie mostrano un carattere sin-sedimentario rispetto ai depositi alluvionali del pleifig. 2 diagramma a rosetta delle mesofaglie misurate nell’area del bacino del fiume melandro e frequenza relativa delle cinematiche delle faglie. rose diagram of the mesoscopic faults from the study area and frequency of kinematic behaviour of fault sets. fig. 3 carta morfostrutturale del bacino del fiume melandro. morphostructural map of the melandro river basin. c. martino & m. schiattarella 123 stocene inferiore (giano & martino, 2003). nell’ambito del bacino e dei rilievi al contorno sono stati individuati quattro ordini di superfici (fig. 3) che decrescono di quota sia lungo il fianco occidentale (monti della maddalena) che lungo quello orientale (fig. 4). l’ordine più antico (s1) corrisponde alla paleosuperficie auctt. di età altopliocenica: sulla sommità della dorsale dei monti della maddalena, e segnatamente in località la conca, rasa infatti depositi marini del pliocene inferiore-medio. morfologicamente incastrate nel paleopaesaggio s1 appaiono le superfici s2, s3 ed s4. le superfici s3 rasano il riempimento continentale del bacino della valle del melandro, datato al pleistocene inferiore (lippman provansal, 1987): ciò permette di attribuire tale ordine alla parte alta del pleistocene inferiore. le superfici s2, interposte tra quelle s1 ed s3, sono conseguentemente attribuibili al pleistocene inferiore. infine, le superfici s4 sono state certamente disattivate nel pleistocene superiore, in accordo con quanto rilevato in aree limitrofe da schiattarella et al. (2003), e pertanto la loro genesi può essere compresa tra la parte alta del pleistocene medio e il pleistocene superiore. le superfici s1, modellate nel pliocene superiore, sono state tettonicamente sbloccate durante l’inizio del pleistocene inferiore (b r a n c a c c i o et al. , 1991; s c h i a t t a r e l l a et al. , 2003), mentre quelle s2, che si sono formate prima della deposizione del riempimento continentale del bacino della valle del melandro, hanno iniziato a sollevarsi durante l’episodio tettonico emiliano (d’argenio et al., 1986), ed in particolare in corrispondenza dell’intervallo 1.2-1.3 ma (s a r t o r i , 1989, 1990; schiattarella et al., 2003). i glacis erosionali s3, modellati dopo l’aggradazione del bacino ad opera dei depositi alluvionali, si sono sollevati al debutto del pleistocene medio (brancaccio et al., 1991; schiattarella et al., 2003), mentre i terrazzi erosionali s4, morfologicamente incastrati nei precedenti, hanno subito un sollevamento durante il pleistocene superiore (0.125 ma in b o r d o n i & v a l e n s i s e , 1998, e sc h i a t t a r e l l a et al., fig. 4 a: panoramica dei monti della maddalena. è possibile osservare la paleosuperficie auctt. (s1), che rasa la sommità della dorsale carbonatica, e le superfici s2 ed s3 in essa morfologicamente incastrate. b: panoramica della destra orografica del bacino. è possibile osservare la superficie sommitale (s1) che rasa i rilievi modellati nella successione mesozoica lagonegrese. incastrate nel paesaggio della paleosuperficie sommitale sono ben evidenti le superfici più giovani s2 ed s3. a: general view of the maddalena mts: note the highest and oldest palaeosurface (s1) cutting the top of the carbonate ridge, and the younger and lower s2 and s3 land surfaces. b: general view of the right flank of the basin: note the summit land surface cutting the top of the mountains formed of lagonegro units, and the younger and lower s2 and s3 land surfaces. fig. 5 esempi di profili morfostratigrafici trasversali al bacino, utilizzati per la stima dei tassi di sollevamento. examples of morphostratigraphic cross-sections through the basin used for the estimate of uplift rates. 2003). la stima dei tassi di uplift, calcolati sulla base della distribuzione altimetrica delle superfici sopra discusse, dei profili morfostratigrafici che ne derivano (fig. 5), e dell’attribuzione dei marker a range di età aspetti morfotettonici ... 124 relativamente ristretti (fig. 6), ha permesso di apprezzare una differente dinamica del sollevamento per i due fianchi del bacino: nel corso del pleistocene inferiore, il versante in destra orografica si solleva più velocemente rispetto a quello opposto, mentre a partire dal pleistocene medio avviene il contrario. in generale, i tassi di sollevamento calcolati per l’intero bacino della valle del melandro hanno messo in evidenza un decremento dei valori tra il pleistocene inferiore e quello medio, considerando il sollevamento locale e “partizionato”, a differenza dei dati relativi al sollevamento regionale che descrivono un trend crescente a partire dall’inizio del pleistocene. la comparazione tra le quote dei relitti di superfici erosionali con il profilo longitudinale del fiume sele (fig. 7a), a partire dal torrente pergola (affluente del fiume melandro, che fa appunto parte del sistema idrografico a recapito tirrenico del sele), ha permesso di ipotizzare una formazione in ambiente genetico fluviale e ben al di sopra del livello del mare delle superfici s3 ed s4. queste presentano, infatti, un andamento conforme a quello del profilo longitudinale del fiume sele. le superfici s1 ed s2 hanno, invece, un andamento molto regolare e prossimo all’orizzontalità (fig. 7), come possibile conseguenza di una formazione in corrispondenza del livello del mare e geneticamente legata all’azione dell’abrasione marina. queste considerazioni permettono di operare una correzione alla stima dei tassi di sollevamento regionale per le superfici s3, sulla base della differenza di quota che intercorre tra tali superfici ed il paleo-livello di base relativo alla parte alta del pleistocene inferiore, impostato sui conglomerati di eboli (brancaccio et al., 1991). tale correzione modifica l’andamento del tasso di sollevamento regionale e lo rende congruente con i tassi di uplift locale e “partizionato” (fig. 8). inoltre, il tasso di sollevamento regionale così corretto calcolato a 1.2 ma risulta essere pari a circa 1 mm/a, che è un valore corrispondente al tasso di subsidenza del bacino di marsili, stimato per lo stesso periodo da sartori (1989). le superfici s1 sono riconducibili alla paleosuperficie auctt. a sviluppo regionale, la cui formazione è avvenuta durante il pliocene superiore. in questo periodo il rilievo era molto modesto (bartolini, 2003), per cui le oscillazioni positive del livello del mare hanno giocato un ruolo fondamentale nello spianamento di aree molto ampie (fig. 9). un discorso analogo sembra valere anche per le superfici s2, che in parte sono state modellate sempre in corrispondenza del livello del mare a partire dalle morfologie dei paleopaesaggi altopliocenici e quindi ereditate dalle superfici s1. considerando un intervallo temporale di formazione per la superficie s1 di almeno 0.4-0.5 ma, che termina a 1.8 ma con l’inizio del sollevamento, si può osservare dalla curva eustatica che in questo periodo il livello del mare si trovava mediamente a -40 m rispetto all’attuale (fig. 10). all’interno di questo intervallo temporale vi sono state almeno cinque importanti oscillazioni positive del livello del mare (rispetto ai -40 m), che con ogni probabilità hanno giocato un ruolo fondamentale nel modellamento della superficie. per le superfici s2 si può ipotizzare un periodo di formazione più breve (circa 0.25 ma), essendo queste in parte il prodotto del rimodellamento di quelle s1, come segnalato per la vicina area della val d’agri (boenzi et al., 2004). la comparafig. 6 diagrammi relativi alle variazioni nel tempo dei tassi di sollevamento regionali, locali e locali partizionati stimati per l’area del bacino del fiume melandro. diagrams showing the variations during the quaternary of regional, local and stage uplift rates from the melandro basin area. zione con la curva eustatica suggerisce che le superfici s2, sollevate a partire da 1.2 ma (schiattarella et al., 2003), si sono formate in un periodo in cui il livello del mare si trovava mediamente a -60 m. probabilmente gran parte del modellamento è avvenuto ai due estremi di tale intervallo temporale, in coincidenza di due significative risalite del livello del mare (fig. 10). le superfici s3 ed s4 sono state modellate a quote di alcune centinaia di metri al di sopra del livello del mare (fig. 7), presumibilmente durante periodi freddi, come ipotizzato da lippman provansal (1987) per la formazione dei glacis corrispondenti alle superfici s3, avvenuta in ambiente periglaciale. il fatto che in simili contesti morfoclimatici si possono formare aree pedemontane sub-pianeggianti molto ampie è in accordo con l’estensione delle superfici s3 ed il loro raccordo morfologico a profilo concavo con i versanti adiacenti (fig. 11). i glacis erosionali s3 sono caratterizzati da un carapace di alterazione spesso alcuni metri. in corrispondenza delle alluvioni del pleistocene inferiore, tale orizzonte è caratterizzato da una generale ossidazione dei depositi che conferisce una tipica colorazione rossastra. laddove la superficie s3 insiste sul substrato c. martino & m. schiattarella 125 fig. 7 a) comparazione del profilo longitudinale del fiume sele -torrente pergola con i lembi dei diversi ordini di superfici erosionali relitte; b) ricostruzione della paleomorfologia delle stesse superfici effettuata sulla base della restituzione del rigetto delle faglie. a) comparison of longitudinal stream profile of the sele-pergola rivers and land-surface relicts; b) palaeomorphological reconstruction of land surfaces by fault displacement restoration. fig. 8 tasso di sollevamento regionale corretto sulla base della ricostruzione dei paleolivelli di base dell’erosione (cfr. fig. 8). base-level-corrected regional uplift rate (cf. fig. 8). fig. 9 diagramma a blocchi della possibile genesi multitemporale delle superfici erosionali s1 ed s2; a) abrasione marina durante i periodi di oscillazione positiva del livello eustatico; b) successivo modellamento ad opera dei corsi d’acqua. block diagram illustrating the possible two-step origin of the s1 and s2 land surfaces; a) marine erosion during sea-level raising periods; b) subsequent shaping of the surface by fluvial erosion. ➧ aspetti morfotettonici ... pre-quaternario, si può osservare un fronte di weathering spesso 2-3 m, caratterizzato in special modo nei litotipi costituiti da un’alternanza di livelli argillosi e litoidi, come ad esempio nella formazione dei galestri – da blocchi litoidi di varie dimensioni immersi in una matrice argillosa fortemente alterata. inoltre, all’interno della componente argillosa è possibile osservare delle plaghe biancastre, corrispondenti a livelli di precipitazione calcarea prossimi alla superficie, che ricalcano l’andamento della topografia e, segnatamente, delle superfici piane o blandamente ondulate. l’insieme di questi caratteri fa supporre che il carapace di alterazione si sia formato in un clima caldo-umido e con la superficie non ancora dissecata dall’erosione lineare. simili fronti regolitici possono essersi formati poco prima dell’inizio del sollevamento del glacis, periodo in cui si registra un picco eustatico positivo (fig. 10). 4. considerazioni finali il bacino della valle del melandro è caratterizzato da un’evoluzione morfotettonica polifasica che ha determinato una complessa articolazione dei suoi margini. episodi di sollevamento sono intervallati a periodi di stasi durante i quali sono state generate superfici erosionali, organizzate in quattro ordini distribuiti temporalmente dal pliocene superiore al pleistocene superiore. i tassi di sollevamento, calcolati grazie all’attribuzione cronologica per correlazione morfostratigrafica delle superfici ad intervalli temporali sufficientemente vincolati, hanno permesso di evidenziare un comportamento differenziale del sollevamento dei due fianchi del bacino, più rapido in destra orografica durante il pleistocene inferiore e a velocità invertite a partire dal pleistocene medio. in generale, i tassi di uplift calcolati per l’intero bacino della valle del melandro mostrano per il sollevamento locale e “partizionato” un decremento dei valori tra il pleistocene inferiore e quello medio, a differenza dei dati relativi al sollevamento regionale che descrivono un andamento crescente a partire dall’inizio del pleistocene. la ricostruzione del paleolivello di base riferibile alle superfici s3 ed s4 per126 fig. 10 intervalli cronologici in cui si sono modellati i diversi ordini di superfici, nel quadro della curva eustatica plio-quaternaria (modificata da bintanja et al., 2005, per il primo milione di anni; per la restante parte ricavata dalla curva degli isotopi dell’ossigeno di gradstein et al., 2004). time intervals related to the genesis of different land surface, in the frame of the global sea level curve (modified after bintanja et al., 2005, for the last 1 my, and reconstructed for the remaining part by means of marine oxygen-18 isotope curve after gradstein et al., 2004). fig. 11 raccordo concavo tra il versante settentrionale del monte il crocifisso e la superficie s3 di serra murgia longa, impostata sui conglomerati del pleistocene inferiore. concave profile of the northern slope of mt. il crocifisso connected with the s3 land surface of the serra murgia longa lower pleistocene conglomerates. c. martino & m. schiattarella mette di operare una correzione al valore del tasso di sollevamento regionale, che in seguito a questa modifica assume un trend comparabile con quello del sollevamento locale e “partizionato”. la comparazione tra il profilo longitudinale del fiume sele con i lembi delle superfici relitte ha permesso di ipotizzare per le superfici s1 ed s2 una formazione in corrispondenza del livello del mare e per quelle più giovani (s3 ed s4) un modellamento avvenuto alcune centinaia di metri al di sopra del livello di base assoluto. le superfici s1 ed s2 sono state modellate probabilmente durante le oscillazioni positive del livello del mare del pliocene superiore e del pleistocene inferiore. al contrario, le superfici s3 ed s4 sono state scolpite durante fasi climatiche fredde che hanno generato ampi glacis in roccia. inoltre, le superfici s3 sono caratterizzate da uno spesso carapace di alterazione probabilmente prodotto in un clima caldo-umido. si può dunque ipotizzare che il glacis s3 è il prodotto derivante dall’accoppiamento di un regime climatico di tipo periglaciale, che ha favorito lo spianamento, con un successivo periodo caldo-umido, durante il quale è stata alterata la superficie. ringraziamenti gli autori desiderano ringraziare due referee anonimi per gli utili suggerimenti. lavoro finanziato con il contributo cofin prin 2005, unità operativa dell’università della 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(1993) quaternary uplift of southern italy. journ. geophys. res., 98, 21741-21772. 128 ms. ricevuto il 6 giugno 2006 testo definitivo ricevuto il 17 ottobre 2006 ms. received: june 6, 2006 final text received: october 17, 2006 c. martino & m. schiattarella imp.bottari& evidenze dell’antico portus pelori da analisi paleotopografiche della penisola di capo peloro (sicilia nord-orientale) antonio bottari 1, carla bottari 2 & pietro carveni 3 1 osservatorio sismologico università di messina, via osservatorio 4, 98121 messina, italia, fax +39090363533, e-mail bottari@unime.it 2 istituto nazionale di geofisica e vulcanologia, via di vigna murata 605, 00143 roma, italia, fax +390651860507, e-mail bottari@ingv.it 3 dipartimento di scienze geologiche, università di catania, corso italia 57, 95129 catania, fax +39095412646,e-mail carveni@unict.it riassunto: bottari a., bottari c. & carveni p., evidenze dell’antico portus pelori da analisi paleotopografiche della penisola di capo peloro (sicilia nord-orientale). (it issn 0394-3556, 2006). il peloro, geograficamente la più orientale propaggine della sicilia settentrionale, identificabile con la penisola di capo peloro, in età greca e romana era un’area antropizzata che si era sviluppata intorno al primo insediamento umano conosciuto della sponda siciliana dello stretto di messina (2200 – 2000 a.c.). fonti storiche diverse menzionano che già dal v secolo a.c. grandi flotte di navi sia siracusane sia puniche approdavano al peloro e vi sostavano anche per lunghi periodi. rilevato che la morfologia attuale della penisola di capo peloro non presenta alcuna insenatura protetta dalle traversie del mare e capace di offrire riparo a flotte di centinaia di navi, si sono svolte indagini geomorfologiche al fine di accertare se quanto storicamente documentato sia compatibile con una paleotopografia dei luoghi. l’approccio adottato si basa sull’analisi delle caratteristiche morfotettoniche dell’area del peloro e specificatamente della evoluzione morfotettonica della sua pianura costiera, a seguito del sollevamento regionale che l’ha interessata nel quaternario e, particolarmente, durante gli ultimi 0,7 ma. la configurazione dello stretto di messina rappresenta infatti il risultato di un elevata mobilità verticale e del progressivo sollevamento che hanno interessato aree di sedimentazione corrispondenti ad un sistema complesso di fosse tettoniche controllate da faglie normali a prevalente direzione ne-sw ed e-w. i dati della letteratura geologica, unitamente a ritrovamenti di resti architettonici monumentali, nonché alcuni riscontri con fonti storiografiche, supportano per gli ultimi 2500 anni una stima del sollevamento della penisola di capo peloro di ~ 1,7 metri. le modellazioni della paleotopografia della pianura costiera, riferibili al v secolo a.c., configurano una maggiore estensione del pantano piccolo e, particolarmente, il suo collegamento con il mare tirreno, attraverso un canale largo un centinaio di metri. tale risultato induce a localizzare l’antico porto del peloro nel bacino del pantano piccolo che per estensione poteva ospita-re sino a 320 navi trireme. una tale collocazione, a poco meno di un miglio marino da capo peloro, giustifica il comune riferimento al peloro, trova riscontro nelle distanze, sia terrestri sia marittime, dalla polis di messana (oggi messina) riportate da differenti fonti storiche e, per la sua minore distanza dagli approdi di skillayon e columna in calabria, risulta anche compatibile con l’appellativo di trajectus. abstract: : bottari a., bottari c. & carveni p., paleotopographic analysis of peloro cape peninsula: evidence of the ancient portus pelori (ne sicily, italy). (it issn 0394-3556, 2006). from the archaic to the late roman period the name “peloro” was used to indicate an anthropic area developed around the first known human settlement on the sicilian shore of the straits of messina. it was geographically the most eastern tip of north sicily and today it is identified with the peloro cape peninsula. such a settlement has been dated to 2200 ÷ 2000 b.c. through recoveries of ceramic fragments. different historical sources mention that at the 5th century b.c. numerous syracuse and carthaginian naval armadas landed for long periods at peloro. given that at present day the morphology of peloro cape peninsula does not have any protected shelter to offer repair to hundreds of naval ships as documented by historians, geomorphologic surveys have been carried out in the area to verify whether historical documents are consistent with the paleotopography of the study area. the approach is based on the analysis of the morphotectonic characteristics of the peloro and specifically on the morphotectonic evolution of its coastal lowland, following the regional uplift that has interested it during the quaternary and particularly in the last 0.7 myr. the straits of messina configuration is the result of a progressive uplift that interested the sedimentation areas correspondent to a complex system of tectonic grabens controlled by ne-sw and e-w normal faults. the geological data together with the uncovered remains of ancient buildings and the shells of present day molluscs found in the study area, as well as some comparison with historiographical sources, support that the uplift of peloro cape peninsula is of about 1.5 ÷ 2.0 metres in the last 2500 years. the modelling of the paleotopography of the coastal lowland, referred to the 5th century b.c., shows a major extension of the pantano piccolo and particularly its connection with the tyrrhenian sea through a canal hundreds of metres wide. such a result induces as to locate the ancient peloro harbour in the basin of the pantano piccolo, which for extension and depth could have sheltered up to 320 ships. such a location of the ancient harbour at about one nautical mile from peloro cape is also supported by different historical sources which report the distances from the polis of messana (the present day messina) and justifies also the appellative of “portus pelori” (peloro harbour). parole chiave: geoarcheologia, sollevamento tettonico, penisola di capo peloro, pantano piccolo, portus pelori, modellazione paleotopografica. keywords: geoarchaeology, tectonic uplift, peloro cape peninsula, ancient peloro harbour, pantano piccolo salt marsh, paleotopography modelling. il quaternario italian journal of quaternary sciences 19(1), 2006 167-174 168 a. bottari, c. bottati & p. carveni 1. introduzione la penisola del peloro, estremo lembo nordorientale della sicilia, in epoca greca e romana è stata teatro di vicende belliche e snodo di importanti traffici marittimi che hanno segnato la storia di messana, l’attuale messina (fig. 1). tuttavia, in tale ambito, taluni avvenimenti pongono interrogativi, tuttora non ancora risolti, principalmente per la difficoltà di individuare con precisione la collocazione geografica di un importante porto menzionato da varie fonti storiche. alcuni studiosi contemporanei, quali aricò (1999) e prestianni giallombardo (2002 a; 2002 b), hanno ipotizzato che dette difficoltà derivino dalle mutate condizioni della superficie topografica della penisola peloritana e che, pertanto, un’analisi dell’evoluzione geomorfologia recente di questa parte del territorio siciliano potrebbe fornire elementi utili per superare le attuali incertezze. nell’ambito di tali problematiche rientra l’ubicazione dell’antico portus pelori che, nel v secolo a.c., ospitava intere flotte navali, sia cartaginesi sia siracusane, e che nel iii secolo a.c., durante la i guerra punica, offrì riparo alla flotta romana che rientrava da cartagine. la difficoltà origina dalla circostanza che, al presente, lungo le attuali rive della penisola del peloro non c’è traccia di una baia che possa essere stata utilizzata per l’ormeggio delle antiche navi. scopo del presente lavoro è pertanto quello di verificare se, tenendo conto dell’evoluzione morfotettonica recente della penisola del peloro, la paleotopografia riferibile al v secolo a.c. sia compatibile con l’esistenza di un approdo. 2. brevi note sulle aree lagunari del peloro e di messana il territorio dell’antica messana, l’odierna messina, si estendeva dalla zona falcata a sud, contigua alla polis, sino al capo peloro a nord (fig. 2). gli estremi di tale territorio erano caratterizzati dai terreni pianeggianti, sabbiosi ed a tratti lagunari, della pianura costiera che orlava i versanti ionico e tirrenico dei monti peloritani. l’estensione dell’attuale area lagunare del peloro risulta alquanto ridotta rispetto a quella antica, presentando due soli bacini salmastri, denominati pantano piccolo (o laguna di faro) e pantano grande (o laguna di ganzirri) (fig. 1). infatti, nell’area di margi, sita tra detti pantani, si trovava sicuramente una laguna oggi non più esistente o forse altre due (solino, iii d.c.). a differenza del pantano grande, di forma allungata e con acque poco profonde ( massimo 6,5 metri) il pantano piccolo ha forma circa circolare ed acque profonde sino a 29 m (abbruzzese & genovese, 1952). recenti lavori di restauro del settore occidentale della cinta bastionata della medioevale torre peloro, sita sulla costa tirrenica del capo peloro (f in fig. 3), hanno condotto al ritrovamento di alcune strutture architettoniche, in via preliminare ascritte ad età romana, parzialmente celate dalle mura della cinta (bacci, 2001; prestianni giallombardo, 2002 b). trattasi di un’ampia platea sulla quale poggia un lungo tratto di podio gradinato in calcestruzzo, con rivestimento in laterizio e copertura di malta idraulica. in atto, il livello del piano d’imposta di detta struttura si trova a poco meno di 1 metro s.l.m.m. ad oggi, pur in mancanza di figura 1 foto aerea della penisola di capo peloro (ne sicilia), riproducente i bacini salmastri di pantano piccolo (pp) e di pantano grande (pg). evidente la notevole urbanizzazione dell’area del peloro e, per la trasparenza delle acque, il fondo poco profondo (1 ÷ 3 m) del settore occidentale del bacino del pp. satellite picture of peloro cape peninsula with the location of the salt marsh basins of pantano piccolo (pp) and pantano grande (pg). the high numbers of houses in the area of peloro testifies the high urbanization, while the transparency of the waters point out shallow deep waters (1÷3) in the western sector of the basin pp. un’analisi archeologica che consenta il riconoscimento certo della funzione originaria della struttura venuta alla luce, la sua ubicazione a poche decine di metri dalla riva del mar tirreno, il livello d’imposta prossimo a quello del mare e l’impiego di malta idraulica inducono a ritenere che possa trattarsi di una struttura di collegamento con il mare, forse per l’alaggio delle navi. la zona lagunare interna alla penisola (detta la falce, s in fig.2) che conforma il porto di messina era contigua all’antica polis di messana, e dall’inizio del secolo scorso non esiste più a seguito di vari lavori di prosciugamento effettuati nel tempo (p r e s t i a n n i g i a l l o m bardo, 2002 a). un' importante testimonianza di rapide variazioni del livello del mare avvenute nell'olocene è data da bonfiglio et al. (1994) e da b o n f i g l i o (1999): gli autori, analizzando i risultati di alcuni carotaggi eseguiti circa 150 metri a meridione del porto di messina (c in fig. 2), hanno rilevato una serie di depositi olocenici poggianti in discordanza su conglomerati medio-pleistocenici; l'analisi dei depositi olocenici ha evidenziato un improvviso approfondimento di circa 20 metri del mare, cui ha fatto seguito una parziale chiusura del bacino di sedimentazione, seguita da una completa emersione della zona; la brusca sovrapposizione dei depositi marini olocenici su quelli medio-pleistocenici e il rapido approfondimento dei fondali testimoniano un rapido abbassamento di origine tettonica, cui ha fatto seguito un sollevamento dell'area in solido con l'intera dorsale peloritana. questo ultimo episodio è documentato, oltre che dalla diminuzione verso l’alto della profondità dell’ambiente di sedimentazione, dall’attuale livello della sommità dei sedimenti di ambiente marino profondo, che ora è a circa -10 metri rispetto al l.m.m. tale posizione documenta che la diminuzione della profondità osservata nella serie non è esclusivamente attribuibile al riempimento del bacino per l’apporto dei detriti, ma anche ad un sollevamento tettonico di circa 15 metri. può dedursi che anticamente la linea di costa meridionale all’interno del porto era posizionata circa 150 metri più a sud dell’attuale e che, ancora prima, durante il neolitico, il mare occupava aree più estese verso sud (bonfiglio et al., 1994). quanto rilevato, particolarmente circa l’ubicazione di aree lagunari sia al peloro sia nella zona del porto di messana, indica un minor livello della pianura costiera rispetto all’attuale. ciò è congruente con il generale sollevamento della catena e, localmente, con la subsiden169evidenze dell’antico portus pelori ... za conseguente lo slip delle faglie normali orientate circa parallelamente alla linea di costa (nne-ssw a messina; ene-wsw, wnw-ese al peloro; fig. 3). il complesso delle osservazioni, evidenziando alcuni caratteri dell’evoluzione geomorfologica recente delle aree litoranee di messina, induce a ritenere che anticamente la topografia delle medesime sia stata apprezzabilmente differente dall’attuale. 3. cenni storici diodoro, storico del i secolo a.c., riferisce che nel 396 a.c. una flotta cartaginese di 600 navi approdò al peloro da dove un contingente di 200 navi proseguì alla volta del porto di messana, noto per la sua tipica forma a falce, per cogliere di sorpresa gli abitanti della polis. inoltre, polibio (in walbank, 1957) e lo stesso diodoro menzionano che durante la prima guerra punica (264 a.c.) i romani, schieratisi in aiuto dei mamertini di messina contro i cartaginesi, ripararono circa 300 navi che rientravano da cartagine in un porto sito nei pressi di capo peloro. ancora, fonti storiche successive, quali gli itineraria di età imperiale, registrano che dell’ingente figura 2 mappa schematica del territorio a nord dell’antica messana, il porto detto la falce (s), nonché i percorsi terrestri e marittimi da/per il portus tragecynus/trajectus ubicati al peloro. c indica l’ubicazione dei sondaggi geognostici eseguiti a sud della banchina meridionale del porto di messina. map of the northern territory of messana (today messina) showing the harbour named sickle (s) and sea ways and road ways from/for the portus tragecynus / trajectus placed at peloro. the letter c indicates the geognostic borings carried out to south of messina harbour quay. 170 traffico di merci ed uomini da e per messana una parte cospicua non transitava dal porto interno alla polis, denominato la falce (s in fig. 2), bensì da un port(us) tragecynus (columba, 1906) ubicato al peloro. detto port(us) tragecynus, richiamato nella tabula peutingeriana può essere riferito al trajectus menzionato nell’itinerarium antonini poiché la distanza da messana, riportata da entrambe le fonti (uggeri, 1968; uggeri, 1997-1998; prestianni giallombardo, 2002 a) è la stessa: 12000 passus ~ 17,76 chilometri. nell’itinerarium maritimum (cannavò, 1982) esso è invece localizzato a 70 stadi, ossia a ~ 13,7 chilometri da messana. tali distanze, considerate sia come percorsi terrestri sia marittimi, individuano un tratto di costa tirrenica della penisola di capo peloro, compreso tra le odierne località di mortelle e torre bianca, distanti fra loro ~ 3 chilometri (fig. 2). oggi, in corrispondenza della pianura costiera che orla la penisola di capo peloro non vi sono tracce né di un porto né di una insenatura capace di offrire un sicuro riparo al naviglio di quel tempo. pertanto, in mancanza di una descrizione accurata degli antichi luoghi o di resti comprovanti l’esistenza di un’antica statio navalis al peloro, si è presa in considerazione l’ipotesi di aricò (1999) che suppone il bacino del lago di faro (fig. 1), reso comunicante con il mare tramite un canale artificiale, sia stata la sede dell’antico porto menzionato dalle varie fonti storiche sopra citate. muovendo dalle incertezze derivanti dalla incompletezza dei riferimenti storiografici si sono pertanto avviate indagini in loco e si è analizzata l’evoluzione geomorfologica più recente della costa peloritana, nel contesto della tettonica attiva dell’area dello stretto di messina, al fine di verificare se dette incertezze possano essere rimosse in base ad analisi morfotettonica. 4. caratteristiche geologiche e morfotettoniche della pianura costiera di capo peloro la penisola di capo peloro, zona delle nostre indagini, è ubicata sulla sponda occidentale dello stretto di messina. la formazione geologica geometricamente più profonda affiorante nella zona dello stretto è data da metamorfiti d’alto grado premesozoiche, trasportate in falda durante il miocene e formanti la parte alta delle unità dell’aspromonte (lentini et al., 2000); immediatamente sopra alle citate metamorfiti giace un conglomerato poligenico sterile, composto prevalentemente da ciottoli provenienti dalle sottostanti metamorfiti; detto figura 3 mappa geologica della penisola di capo peloro. pp: pantano piccolo; pg: pantano grande; g: faglia di ganzirri; h: faglia di faro; i: faglia di mortelle; f: torre peloro. geological map of the peloro cape peninsula. pp: pantano piccolo; pg: pantano grande; g: ganzirri fault; h: faro fault; i: mortelle fault; f: ancient tower. a. bottari, c. bottati & p. carveni 171 conglomerato evolve verso l’alto ad un’alternanza arenaceo-marnosa di età tortoniana (jacobacci et al., 1961). in continuità di sedimentazione sui termini tortoniani si trovano limitati lembi della serie gessoso-solfifera siciliana di età messiniana, composti da marne tripolacee, calcare brecciato e gessi (jacobacci et al., 1961). in trasgressione sui depositi messiniani giacciono marne bianche a globigerine infraplioceniche (trubi) (jacobacci et al., 1961), cui fanno seguito, sempre in trasgressione, calcareniti del pleistocene inferiore (lombardo 1980 a; 1980 b), su cui poggiano le argille di vito superiore di età infra-pleistocenica. su tutte le formazioni descritte poggiano in discordanza le ghiaie medio-pleistoceniche della formazione di messina cui fanno seguito depositi terrazzati continentali (lombardo 1980 a; 1980 b), alluvioni recenti, alluvioni e depositi di spiaggia attuali. la penisola di capo peloro può essere suddivisa in due parti: la zona collinare e la spianata alluvionale; la serie stratigrafica affiorante è costituita alla base da rocce cristalline, su cui poggiano i termini della serie tortoniana e le ghiaie della formazione di messina; la spianata alluvionale è formata da depositi alluvionali recenti ed attuali. l’attuale configurazione dello stretto di messina è il risultato di un’elevata mobilità verticale e di un progressivo sollevamento che hanno interessato aree di sedimentazione interne a fosse tettoniche controllate da faglie normali orientate prevalentemente nne-ssw, ne-sw e circa e-w. focalizzando l’attenzione sulla sponda siciliana dello stretto, le indagini sono state rivolte ai terreni della penisola di capo peloro, mediante l’analisi fotogeologica e la ricerca di elementi morfologici indicativi dell’attività di faglie durante il pleistocene e l’olocene. questa fase delle indagini ha condotto a riconoscere nelle faglie di mortelle, pantano piccolo e granatari (fig. 3) strutture la cui attivazione è avvenuta in tempi recenti (ghisetti, 1992; bottari et al., 2005 a: 2005 b). tali risultati sono congruenti con quelli di campagne di rilievi geofisici (del ben, 1985; finetti & del ben, 1985), di analisi della paleosismicità (valensise & pantosti, 1993), di deformazioni avvenute in seguito del terremoto calabro-messinese del 1908 (lo perfido, 1909; baratta, 1910) e di analisi dei meccanismi focali (caccamo et al., 1996; neri et al., 1996; frepoli & amato, 2000). l’attività di dette faglie, delimitando a monte la pianura della penisola di capo peloro, riduce localmente il sollevamento regionale che interessa l’area in studio da ~ 0,7 ma ( montenat et al., 1987; westaway, 1993). sulla sponda siciliana dello stretto di messina, un profilo eseguito da torre faro a monte ciccia, mostra superfici suborizzontali di abrasione, derivate da terrazzi marini, le quali indicano una velocità di sollevamento di ~ 1 mm/a (westaway, 1993). localmente è stato rilevato lo strombus bubonius non più in alto di 85 metri s.l.m. (bonfiglio & violanti, 1983), quota compatibile con un tasso di sollevamento di ~ 0,65 mm/a (~ 85 m/ 130 ka). inoltre, questa costa, bordata da faglie normali, presenta numerose faglie en échelon, ciascuna con una velocità di slip verticale di ~ 0,1 ÷ 0,2 mm/a (ghisetti, 1992). discende che il sollevamente varia apprezzabilmente da sito a sito. westaway (1993) valuta in ~ 0,9 mm/a la componente regionale del sollevamento, con variazioni locali per gli effetti della fagliazione normale > ~ 0,2 mm/a . pertanto, assumendo per la velocità del sollevamento regionale della sponda siciliana dello stretto il valore di 0,9 mm/a, corretto localmente per velocità di slip verticale di 0,2 mm/a, si ottiene per gli ultimi 2500 anni un sollevamento di 1,75 metri. adottando il dato di bonfiglio & violanti (1983) si ottiene un valore di poco inferiore, pari a 1,625 metri. in letteratura, il dato più recente sul tasso del sollevamento dell’area peloro ganzirri, determinato con mis 5,5, è di 704 mm/ka (antonioli et al., 2005), che in 2500 anni significa un sollevamento di 1,76 metri. pertanto, sulla base dei valori della letteratura, si può assumere che negli ultimi 2500 anni il sollevamento dell’area del peloro sia stato di ~1,70 metri. concludendo, l’analisi della morfotettonica dell’area del peloro mette in evidenza come l’attuale configurazione della zona in studio rappresenti il risultato di un’elevata mobilità verticale e di un progressivo sollevamento, localmente ridotto dallo slip di alcune faglie normali. rilevato ancora che in atto alcuni settori della pianura del peloro mostrano quote < 1 m s.l.m., si è orientato il proseguimento dell’indagine verso la ricostruzione dell’antica configurazione dei luoghi. 5. modellazione della paleotopografia della penisola di capo peloro per tutto quanto sopra richiamato, ed allo scopo di verificare se la ricostruzione dell’antica topografia della pianura del peloro possa dare indicazioni circa l’esistenza di un’antica baia, sufficientemente capiente e ben protetta dalle traversie del mare, o comunque fornire elementi a supporto dell’ipotesi di aricò (1999), che il porto antico del peloro fosse allocato nel bacino del pantano piccolo, si sono eseguite modellazioni digitali della superficie topografica adottando il software arcview, applicate alle quote derivate da immagini da satellite rilevate nel 2001 (regione siciliana). dette quote hanno incertezza assoluta dell’ordine di 10 cm ed incertezza relativa dell’ordine del centimetro. la modellazione opera sulle quote di punti del piano campagna aventi interdistanza media di 50 metri. la ricostruzione della paleotopografia della piana costiera è stata eseguita tramite digitalizzazione della carta topografica, previo filtraggio delle quote, al fine di eliminare le maggiori alterazioni topografiche operate dall’uomo, a seguito della realizzazione di artefatti vari (edifici, rilevati in terra, strade rialzate, canali, ecc.). essa tiene conto del sollevamento tettonico, simulando un equivalente abbassamento del livello medio del mare, rispetto alla terra ferma, con un tasso medio di 704 mm/ka. la zona di margi, che in atto presenta anch’essa quote del piano di campagna inferiori a un metro, è stata tuttavia esclusa dalla fase del filtraggio e dalle successive modellazioni, in considerazione delle alterazioni subite dalla superficie naturale del terreno originario a seguito dei lavori di bonifica delle saline eseguiti nella prima metà del xix secolo. tali alterazioni non possono essere filtrate poiché non si dispone di evidenze dell’antico portus pelori ... 172 una accurata documentazione che consenta di distinguere l’antico andamento della superficie topografica sulla quale è stato riversato il materiale alluvionale utilizzato per prosciugare le antiche saline. la simulazione si basa sull’assunzione che 2500 anni addietro, assumendo un tasso medio di sollevamento di 704 mm/ka, il livello medio del mare fosse 1,70 metri più elevato rispetto alla costa considerata fissa, e che pertanto le zone della pianura costiera con altitudine attuale inferiore a 1,7 metri fossero a quel tempo sommerse. consegue che a quel tempo la profondità delle acque del bacino di faro era in eguale misura maggiore dell’attuale. le modellazioni eseguite sono rappresentate nella figura. 4, ove le mappe b e c rappresentano le topografie riferibili, rispettivamente, al v secolo a.c. (∆h = + 1,70 metri) ed al iii secolo d.c. (∆h = + 1,25 metri). in complesso le modellazioni mostrano modeste variazioni delle geometrie della linea di costa, un’apprezzabile quanto prevedibile suo arretramento rispetto alle acque del tirreno ed il conformarsi di una apertura (canale) nei depositi di spiaggia in corrispondenza di torre bianca, che rende comunicanti le acque del mare tirreno con quelle del pantano piccolo. per ∆h = + 1,7 metri tale canale ha una larghezza minima di 120 metri ed una profondità di circa 1 metro; la superficie del bacino risulta più grande dell’attuale, estendendosi prevalentemente verso oriente e ssw (margi). tuttavia, nelle due mappe (fig. 4: b e c), la paleotopografia dell’area di margi non è rappresentata per i motivi sopra richiamati. in sintesi, le variazioni topografiche più importanti, evidenziate tramite le modellazioni eseguite, risultano nell’apertura di un canale sulla costa tirrenica che mette in comunicazione le acque del bacino di pantano piccolo con quelle del mare, una maggiore grandezza dello specchio d’acqua lacustre che porta a 230.000 metri quadrati l’estensione del bacino ove le acque hanno profondità ≥ 3,0 metri. figura 4 modellazioni della superficie topografica della penisola di capo peloro: a) attuale; b) simulando una variazione del livello del mare ∆h = + 1,25 m; c) simulando una variazione del livello del mare ∆h = + 1,70 m. modelling of the topographical surface of peloro cape peninsula: a) present day topographical surface; b) and c) reconstructions of topographical surface with ∆h variations of sea level of +1.00 and +1.70 m, respectively. 6. considerazioni conclusive i risultati delle modellazioni paleotopografiche della pianura costiera del peloro supportano che: a. bottari, c. bottati & p. carveni a) nel v sec. a.c. le acque del pantano piccolo erano comunicanti con quelle del tirreno attraverso un canale naturale largo ~120 metri e profondo ~ 1 metro; il bacino lacustre costituiva così un approdo naturale, ben riparato dalle traversie marine, esteso oltre 300.000 metri quadrati e per ~ il 70% con acque profonde ≥ 3 metri; in tali condizioni esso era però accessibile solo alle piccole navi; diversamente, mediante lavori di dragaggio del canale di accesso, in modo da realizzare una profondità delle acque di almeno 2,5 ÷ 3,0 metri, il bacino diveniva accessibile anche al naviglio maggiore; infatti, sia le trireme del iii secolo a.c., sia le navi da guerra di età augustea, erano lunghe non più di 36 metri, larghe da 5 a 6 metri e con pescaggi non maggiori di 1,5 metri (höckmann, 1988); ne consegue che con un modesto dragaggio del fondo del canale, il bacino poteva ospitare sino a 320 trireme. le navi commerciali, tranne le più grandi navi frumentariae, erano più corte delle trireme, in proporzione più larghe ed, al pari delle navi da guerra, avevano il profilo trasversale della carena relativamente piatto, con pescaggi generalmente non superiori a 2 metri (foley et al., 1982; white, 1984); b) dal vi secolo a.c. le darsene per il ricovero delle navi erano diffuse in grecia, in italia e nell’area fenicio-punica. i greci avevano buona esperienza di scavi per la realizzazione di canali navigabili e per gli ingegneri romani l’apertura di canali per la realizzazione di strutture portuali era lavoro di routine (blackmann, 1982; höckmann, 1988). dragare le sabbie del canale di accesso al pantano piccolo, su un fronte di una ventina di metri, per portare i fondali da -1 a -3 metri, era pertanto tecnicamente fattibile ed economicamente e militarmente conveniente, perché garantiva l’agibilità di un porto sufficientemente ampio da potere ospitare centinaia di navi. inoltre, ciò rendeva possibile salpare/approdare in un tratto di mare che, in quanto esterno rispetto all’imboccatura settentrionale dello stretto, non risentiva delle forti correnti di marea (fino a 7 nodi di velocità) tipiche dello stretto di messina (montenat et al., 1987). per le navi di quel tempo le correnti dello stretto costituivano una seria difficoltà, e pertanto una statio navalis molto prossima al peloro, ma esterna alle acque dello stretto, era sicuramente preferibile al porto della falce di messina quando il traffico di uomini e/o merci era verso/da gli approdi del mediterraneo centro-occidentale; c) la breve distanza di un porto al peloro dagli approdi più vicini della calabria (4,5 chilometri da skyllaion, ora scilla, e 3,8 chilometri da columna) risultando minori delle distanze del porto della falce di messina sia da skyllaion, sia da columna sia da reghium (l’attuale reggio calabria), era il percorso più breve verso/dalla penisola italica. ciò giustifica il termine trajectus menzionato nell’itinerarium antonimi per indicare l’approdo del peloro. in conclusione, per tutto quanto sopra considerato, la ricostruzione della paleotopografia della penisola di capo peloro riferibile al v secolo a.c. indica che essa era compatibile con un approdo conformato dal bacino del pantano piccolo comunicante con il mare tirreno. tale approdo, inoltre, avendo l’accesso distante meno di 1 miglio nautico dal capo peloro, giustifica il comune riferimento al peloro delle fonti storiche in relazione all’ubicazione sia del port(us) tragecynus, sia del trajectus, sia della statio navalis. ricerca eseguita con il contributo del m.i.u.r. nell’ambito della ricerca morfodinamica di zone costiere sismicamente attive (responsabile pietro carveni). ringraziamenti si ringrazia vivamente l’ing. salvatore guarniere che ha collaborato alle elaborazioni gis per la modellazione della paleotopografia. testi citati abruzzese d. & genovese s. 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(1997-1998) itinerari e strade, rotte, porti e scali della sicilia tardoantica. kokalos, 43-44, 299-364. valensise g. & pantosti d. (1993) a 125 kyr-long geological record of seismic record of seismic source repeatability: the messina straits (southern italy) and 1908 earthquake (ms 7 1/2). terra nova, 4, 472-483. walbank f.w. (1957) a historical commentary on polibius, i, oxford 1957, 61-63 westaway r. (1993) quaternary uplift of southern italy. j.g.r., 98, 21.741-21.772. white k.d., 1984 greek and roman technology, pp.104. 174 ms. ricevuto il 16 maggio 2006 testo definitivo ricevuto il 3 novembre 2006 ms. received: may 16, 2006 final text received: november 3, 2006 a. bottari, c. bottati & p. carveni imp.gordini& i depositi cementati del golfo di trieste (adriatico settentrionale): distribuzione areale, caratteri geomorfologici e indagini acustiche ad alta risoluzione emiliano gordini1, ruggero marocco2, giorgio tunis2 & riccardo ramella1 1istituto nazionale di oceanografia e di geofisica sperimentale ogs, trieste egordini@ogs.trieste.it rramella@ogs.trieste.it 2dipartimento di scienze geologiche, ambientali e marine, università degli studi di trieste -marocco@units.it tunis@units.it riassunto: e. gordini, r. marocco, g. tunis & r. ramella, i depositi cementati del golfo di trieste (adriatico settentrionale): distribuzione areale, caratteri geomorfologici e indagini acustiche ad alta risoluzione. it issn 0394-3356, 2004. l’elevato numero (ca. 250) d’affioramenti rocciosi individuati nei fondali poco profondi del golfo di trieste, la loro distribuzione areale e i loro caratteri morfologici essenziali hanno permesso di formulare alcune ipotesi sulla loro genesi e, più in generale, sulle vicende geologiche che hanno interessato questa parte più settentrionale dell’alto adriatico. questi veri e propri geositi che sotto vari punti di vista arricchiscono l’ambiente marino delimitato dalle acque slovene e croate, si distribuiscono essenzialmente nell’ampia fascia delle sabbie di piattaforma (d’orientazione ne-sw) e in quest’ambito maggiormente (85%) nel versante che degrada verso le profondità maggiori. analoghe ricerche eseguite sul golfo di venezia e nel versante sloveno dell’alto adriatico, fanno ritenere che queste rocce siano molto diffuse (sull’ordine delle migliaia) e che la loro presenza condizioni la morfologia e la vita acquatica di questo mare. nell’area indagata la maggioranza degli affioramenti presenta una tipologia essenzialmente tabulare e subordinatamente a “panettone” e pinnacoli; la loro concentrazione massima è di 3,2 affioramenti per km2. l’analisi statistica elementare effettuata su un numero rappresentativo di affioramenti ha evidenziato che essi si rinvengono a profondità mediamente pari a 17,1 m (min 8,3 e max 21,5 m), e presentano spessori compresi tra un massimo di 2,7 ad un minimo di 0,4 m (medio 1,0 m). la tipologia di affioramento è stata definita in otto classi che comprendono forme essenzialmente tabulari (con quattro sottoclassi; da a a d, complessivamente 89%), a panettone (e, 1%) e pinnacolari (f, pari al 10%). la classe tabulare è stata suddivisa ulteriormente a seconda della disposizione rispetto al fondale (apicale su alti morfologici, intensamente fratturato con nucleo più esteso, compatto e tondeggiante, assetto inclinato) nelle forme b1 (27%), b2 (10%), b3 (36%) e c (6%) mentre a seconda dello spessore, forma ed associazione con altri affioramenti nella tipologia d (9%). raramente questi fondi duri si rinvengono nelle aree di bassura sottomarina (6%) o alla sommità delle trezze (secche, 9% circa), sempre però nell’immediato intorno delle sabbie di piattaforma (36 % sulle sabbie pelitiche e l’1% nelle peliti molto sabbiose). in questa fase della ricerca di particolare importanza si sono rivelate le osservazioni dirette in immersione che hanno palesato ammassi di concrezioni organogene poggianti su substrati costituiti da lastroni di sabbia cementata, adagiati o affioranti sul fondale sabbioso. questi presentano solitamente fratture ortogonali alla stratificazione, altre ad andamento casuale e quasi sempre più o meno profonde nicchie d’erosione alla base che non fanno intravedere, però, una continuità con il substrato. per far questo si è impiegata la metodologia sub-bottom profile chirp che ha permesso di indagare con notevole dettaglio l’assetto sedimentario del sottofondo marino (da 7 a 14 m ca.), con una risoluzione compresa tra 20 e 30 cm. emerge che la maggioranza degli affioramenti tabulari presenta un limitato o talvolta quasi assente sviluppo radicale, che si esaurisce all’interno del materasso sabbioso riconducibile al tetto dei depositi continentali del sistema lst (30-40 cm dal fondo). anche gli affioramenti a forma di “panettone”, che presentano radici più profonde, sono radicati ai depositi continentali del corpo sedimentario lst, costituito da facies acustiche prevalentemente piano parallele, variabili in ampiezza e frequenza, con orizzonti torbosi e una diffusa presenza di gas, manifestata da evidenti lacune acustiche tipiche. anche in superficie, sulla verticale degli affioramenti a volte si riscontrano emanazioni di gas e sul fondo si sono riconosciute macchie di solfo-batteri che porterebbero ad ipotizzare una genesi per ossidazione del metano. ulteriori studi sono attualmente in corso al fine di verificare tali ipotesi. sulla base dei dati raccolti e soprattutto dalle risultanze delle prime analisi dei campioni di roccia si è propensi a ritenere che gli affioramenti rocciosi del golfo di trieste siano un insieme di forme poligeniche (costituite da depositi litorali e marini, ma anche alluvionali) messe a giorno dalla trasgressione versiliana e poi rielaborate dai processi biologici e geomorfici attualmente in atto sui fondali adriatici. abstract: e. gordini, r. marocco, g. tunis & r. ramella, the cemented deposits of the trieste gulf (northern adriatic sea): areal distribution, geomorphologic characteristics and heigh resolution seismic. it issn 0394-3356, 2004. echo-sounding profiles, lateral scanning echo-sounding surveys and scuba divings carried out in several years allowed the identification of at least 250 rocky outcrops in the gulf of trieste. the analysis of the areal distribution and of the main geomorphic characteristics (extension, shape, thickness, etc.) showed that these very peculiar rocks lie beyond the coastal sedimentary prism (13 to 21 m depth), in correspondence to the shelf sands, displaying a ne-sw direction, reaching the gulf of venice. the rocky outcrops are located, almost in continuum, along the southern sides of the banks (the morphological reliefs called “trezze”), and on the small depressions among them, where they reach the maximum values of density of about three outcrops squared kilometres. the outcrops are made of sandstone and they emerge from shelf sands usually (73%) showing planar-tabular morphotypes (with clear stratification), sometimes massive or pinacular, always covered by cap reefs. bubbling reefs, locally defined as “bromboli” are rarely present. their mean thickness is one metre and they show a preferential elongation following the 13, 16 and 19 m bathymetric countours. the statistical analysis performed on morpho-sedimentological parameters characterising these subaqueous outcrops has shown that they are essentially strictly related to the morphology and the water depth such as sediment texture and outcropping type. on the basis of specific characteristics, the rocky outcrops can be divided, at least, into four main groups. direct diving observations highlighted that sandstones are often fractured orthogonally to stratification and appear associated to more irregular trends and small caves or erosional niches at the base. these fractures do not reveal the presence of roots nor do they suggest a further extension under the sea-bed. the sub-bottom profile chirp methodology appeared a good application in the definition of the buried geometric characteristics of these numerous rock outcrops present in the seafloor of the trieste gulf, but also allowed to define a good sedimentological characterization of the sub-surficial sediments. the acoustic penetration of the seismic signal is varying from 7 to 14 meters being notably influenced by the type of investigated sediment, while the resolution range is between 20 and 30 cm. from this study it has emerged that the investigated rock outcrops reveal a limited, or sometimes absent radical development within il quaternario italian journal of quaternary sciences 17(2/2), 2004, 555-563 556 e. gordini et al. 1. introduzione da tempo si sta indagando sugli affioramenti rocciosi del golfo di trieste. in lavori precedenti e attraverso indagini essenzialmente dirette si è messo in evidenza la distribuzione areale e i variegati aspetti morfologici di questi fondi duri che sono una ricchezza biologica per l’alto adriatico (caressa et al., 2001; gordini et al., 2003), tanto da giustificare un inserimento di questi geotopi in aree marine vincolate (fig. 2). la ricerca è proseguita poi, con diverse campagne marine incentrate su indagini indirette (side scan sonar, ecoscandaglio digitale, sub-bottom profiler chirp; gordini et al., in stampa) e dirette (immersioni subacquee, campionature dei sedimenti e delle rocce) attualmente in fase di elaborazione. i risultati fino ad ora raggiunti non permettono di definire con precisione la genesi di questi affioramenti subacquei che secondo altri autori (colantoni et al., 1998; stefanon & zuppi, 2000; conti et al., 2002) sono il prodotto dell’ossidazione del metano fuoriuscito dal sottofondo marino, tramite un meccanismo diagenetico analogo a quello individuato nei mari del nord da jensen et al., 1992 (bubbling reef). l’elevato numero d’affioramenti individuati in una relativamente ristretta area del golfo di trieste, delimitato dai confini con la slovenia e croazia, e i caratteri d’insieme degli affioramenti (estensione, forma, potenza, fatturazione, ecc), inducono ad ipotizzare un insieme di forme poligeniche (costituite da depositi litorali e marini, ma anche alluvionali, “messi a giorno” dalla trasgressione versiliana), rielaborate dai processi biologici e geomorfici attualmente in atto sui fondali adriatici. l’analisi del cemento delle rocce e del gas che gorgoglia dal fondo del mare, oggetto di una prossima ricerca, dovrebbe dar risposta a questi quesiti. 2. generalità ed acquisizione dei dati per l’individuazione degli affioramenti rocciosi si sono utilizzate le numerose segnalazioni dei pescatori e dei subacquei che sono state in parte verificate, poi, con una serie di strisciate batimetriche e side scan sonar. preziosa sotto questo punto di vista è stata la collaborazione con il sub nino caressa di grado che ha fornito circa 250 segnalazioni di affioramenti rocciosi, determinate con traguardi a terra, coordinate loran, e ultimamente, rilevamenti gps (caressa et al., 2001). tutti questi siti sono stati schedati secondo coordinate geografiche, profondità del fondale e spessore (potenza) dell’affioramento; sono state calcolate inoltre la distanza dalla costa e la tipologia morfologica e sedimentologica del fondale circostante. caressa ha fornito anche una succinta descrizione degli affioramenti che ha permesso una prima classificazione della loro forma (caressa et al., 2001). tutti questi dati sono stati, in seguito, verificati in immersione. il rilievo batimetrico è stato eseguito con la m/n “castorino 2” (fig. 1), utilizzando un ecografo x – 16 computer sonar lowrence e un ecoscandaglio digitale lowrence x16c digital computer sonar. la posizione è stata definita in tempo reale con strumentazione gps e dgps. il posizionamento è stato quindi elaborato con un software di navigazione: l’errore planimetrico medio è stato stimato essere inferiore a 5 m. la registrazione del fondo marino è stata corretta considerando la profondità del sensore dell’ecoscandaglio, l’escursione della marea, riportando il valore così ottenuto al livello medio mare locale (trieste). l’errore di profondità stimato è di 10 +/5 cm. in seguito all’individuazione delle aree d’affioramento, su alcuni siti, ritenuti più interessanti, sono stati eseguiti rilievi side scan sonar ed immersioni subacquee. il sistema side scan sonar utilizzato è quello della transceiver unit della edgetech df-1000 dci kit interfacciato con workstation coda octopus; il digital tow fish è della edgetech df-1000 saf-t-link™ digital towfish, con doppia frequenza simultanea di acquisizione 100/500khz. il software utilizzato per l’elaborazione dei dati è il coda geosurvey mosaic. il tow fish è stato trainato a poppa dell’imbarcazione a circa 6 m di profondità e ad una distanza di 15 m. la differenza di posizione tra il “pesce” e l’antenna gps è stata calcolata e inserita nel programma attraverso il software d’acquisizione dati. per il rilievo subacqueo degli affioramenti sono state adottate le normali tecniche scuba. durante le operazioni in immersione, particolare attenzione è stata rivolta alla descrizione della forma dell’affioramento, alla presenza di stratificazioni al letto della roccia, alla disposizione delle fratture e alla presenza, o meno, di fenomeni di gorgogliamento di gas dal substrato. si è passato quindi alla campionatura della roccia e dei sedimenti nell’intorno. the sandy mattress, of the system tst (transgressive sistem tract). the thickness of the rocky outcrops (about 1 m) puts them of to the top of the continental deposits of the lst. in this situation the most reasonable hypothesis about their genesis is referable to lithification processes in the ancient lowland before the sea transgression or to recent cementation processes of the sea foundation. then, they outcropped and underwent the colonization of calcareous algas, briozoas and serpulidi, which provideld actual configuration. the sedimentary body lst is constituted by acoustic facies marked by parallel reflections. they appear predominantly plain, of varying amplitude and frequency, with the main reflectors few meters spaced and thin packages, characterized by less reflectivity. in this alluvial sedimentary blanket, peat horizons and a diffused presence of gas have been recognized, as revealed by transparent facies in the seismic profiles. on the basis of the above data, as preliminary results, due to the high number of surveyed and hypothesised rocky outcrops along with their shape and areal distributions, it is presumed that they were not produced by a single process, but that several different processes interacted on the littoral and marine environment, as well as on alluvial deposits of the paleo-plain, which outcropped as the consequence of the versilian transgression. parole chiave: affioramenti rocciosi, geomorfologia subacquea, facies acustiche, golfo di trieste, italia. keywords: rock outcrops, subacqueous geomorphology, acoustic facies, trieste gulf, italy. grazie a questi rilievi il quadro delle conoscenze sui geotopi ha raggiunto un buon livello e in particolare ha permesso di elaborare statisticamente le informazioni ottenute (elaborazione eseguita su 104 affioramenti dei 250 segnalati inizialmente) e di raggruppare gli affioramenti in otto tipologie morfologiche (caressa et al., 2001). a completamento della ricerca è stata promossa una campagna di indagine acustica ad alta risoluzione nel sottofondo marino utilizzando il sub-bottom profiler chirp (cap-6600 della datasonics con tow vehicle ttv190). la configurazione adottata ha permesso di acquisire contemporaneamente il segnale acustico su due bande di frequenza differenti, rispettivamente con sweeps da 2 a 7 khz e pattern radiativo conico di 45° e simultaneamente anche con sweeps da 8 a 23 khz con cono da 30°. il tow vehicle è stato trainato a poppavia dell’imbarcazione, ad una profondità di 3 m dalla superficie ed ad una distanza di 12 m. la penetrazione ottenuta varia da 7 a 14 m essendo notevolmente influenzata dai diversi tipi di sedimento indagato; la risoluzione è stata mediamente compresa tra 20 e 30 cm. 3. breve inquadramento geologico le caratteristiche del fondo e del sottofondo del golfo di trieste sono il risultato di processi evolutivi tardo-pleistocenici ed olocenici che hanno visto da un lato la progressiva ingressione marina postglaciale e 557i depositi cementati del ... dall’altro l’aggradazione della costa alluvionale, alimentata dai paleofiumi tagliamento ed isonzo, due dei più importanti fiumi dell’italia settentrionale (colantoni et al., 1985; marocco, 1991). la situazione attuale del golfo palesa la presenza lungo costa di un primo esteso prisma sedimentario che copre una fascia continua che va dall’apparato deltizio isontino (ad est) al delta del fiume tagliamento ed oltre (ad ovest), fino alla profondità di ca. 12-13 m (gordini et al., 2003). questo corpo sedimentario presenta la classica stratigrafia di conoide progradazionale ed è costituito da sedimenti fluviali attuali/recenti, rielaborati continuamente dal moto ondoso e dalle correnti litoranee. il prisma sedimentario costiero rappresenta il tratto finale del sistema hst (highstend system tract) che termina in una zona sub-pianeggiante e mossa per la presenza di rilievi sabbiosi e affioramenti rocciosi che si inseriscono nell’ambito dei depositi trasgressivi del tst (trasgressive system tract). la sottile coltre dei depositi trasgressivi (variabile da 30 a 40 cm, salvo valori particolari di 1,5 m in corrispondenza di dune sommerse) assume, in corrispondenza dell’alto morfologico della trezza grande, massima potenza (6 m) e definisce un cono deltizio annegato in seguito all’innalzamento del livello marino nel tardiglaciale (gordini et al., 2002). questi depositi sono sabbie medie e mediofini, carbonatiche derivate da sedimenti rielaborati dalla trasgressione marina (colantoni et al., 1985; marocco, 1991). sono ricchi di frammenti organogeni, alghe calcaree, spugne, molluschi, echinodermi, briozoi, ecc. fig. 1 schema del sistema d’acquisizione dei rilievi acustici (batimetrici, side scan sonar, chirp). sketch of the acoustic profiles acquisition system (echo-sounding, side scan sonar, chirp). 558 essi presentano, nel loro limitato spessore, una gradazione normale con all’interno livelli di tritume conchigliare ad indicare una trazione da parte di correnti di fondo e, in altri casi, contatti erosivi tra sedimenti grossolani e sedimenti pelitico-torbosi continentali. l’età dei depositi trasgressivi non è stata determinata analiticamente; sulla base di considerazioni climatiche ed eustatiche generali e in relazione alla età di formazione del delta tilaventino (marocco,1991) e della laguna di caorle, nel retroterra (ca. 9.000 anni; marocco et al., 1996; galassi & marocco, 1999), si può ritenere che almeno l’annegamento del corpo sedimentario della trezza sia avvenuto tra i 16.000 e 11.300 anni fa (gordini et al., 2002). i depositi sabbiosi sormontano con contatti netti il corpo dei sedimenti pelitico -torbosi continentali del sottofondo, ascrivibili al sistema lst (lowstand system tract) e con età pleniglaciale (da 19.945 a 22.120 anni bp; sempre gordini et al., 2002). per la descrizione morfo-sedimentologica dei fondali del golfo di trieste si rimanda a gordini et al. (2003) e caressa et al. (2001). per quanto riguarda gli studi eseguiti sugli affioramenti rocciosi dell’alto adriatico si rimanda a stefanon (1967); stefanon (1979); braga & stefanon (1969); stefanon & mozzi (1972; 1973) newton & stefanon (1975;1976); boldrin (1979) e recentemente da colantoni et al. (1998); mizzan (1999) oltre a caressa et al. (2001) e gordini et al., in stampa. 4. sintesi dei risultati un primo risultato conseguito da questa ricerca (ancora in corso) è stato l’identificazione di un cospicuo numero di campi d’affioramenti rocciosi, ognuno costituito da più rocce singole, molto ravvicinate e solo in parte conosciute dagli autori precedenti. pertanto questi affioramenti non sono singoli ammassi rocciosi che spuntano dal fondale, ma gruppi di rocce, tutte con caratteristiche abbastanza simili che si estendono su vasti areali marini (fig. 2). solamente le formazioni a “panettone” che sono molto estese (50-80 m), si presentano singolarmente o al massimo in coppia. su un centinaio di campi di rocce sottomarine e sui panettoni è stata condotta un’analisi morfologica quantitativa degli elementi più rappresentativi (forma, estensione, profondità, distanza dalla costa, tessitura e morfologia del fondale circostante, ecc). dalla distribuzione areale dei campi di rocce emerge un andamento abbastanza disperso nell’ambito del golfo, con punti o allineamenti di concentrazione nella direzione ne-sw, che coincide con l’area di distribuzione delle sabbie di piattaforma. quest’area è stata contraddistinta da generali fenomeni d’erosione dei sedimenti superficiali, avvenuta con forte intensità durante la fase trasgressiva postglaciale e ancora presente in forma più lieve in concomitanza con le mareggiate più e. gordini et al. fig. 2 – distribuzione e tipologia degli affioramenti rocciosi nel golfo di trieste. distribution and types of the rocky outcrops in the gulf of trieste. 559 violente. nell’ambito di questo trend distributivo, sembrano assumere particolare valenza i locali allineamenti fra affioramenti morfologicamente simili, distribuiti secondo l’andamento delle batimetriche 13, 16 e 19 m. la concentrazione massima di queste rocce è di 3,2 affioramenti per km2. statisticamente (fig. 3) si rinvengono mediamente a 17,1 m (min 8,3 e max 21,5 m), con spessori compresi tra un massimo di 2,7 ad un minimo di 0,4 m (medio 1,0 m). raramente questi fondi duri si rinvengono nelle aree di basso morfologico o avvallamenti sottomarini (6%) o alla sommità delle trezze (secche, 9% circa), sempre però nell’immediato intorno alle sabbie di piattaforma (36 % sulle sabbie pelitiche e l’1% nelle peliti molto sabbiose). la distanza massima dalla costa è risultata di ca. 17 km, quella minima di 2 e quella media di 10 km. la tipologia d’affioramento è stata definita in otto classi (fig 3 e 4) che comprendono forme essenziali depositi cementati del ... fig. 3 – distribuzione di frequenza dei principali parametri che caratterizzano gli affioramenti rocciosi del golfo di trieste. frequency distribution of the main parameters characterising the rocky outcrops in the gulf of trieste. fig. 4 (a sinistra, 4a) tabella riassuntiva dei principali caratteri morfologici e geometrici degli affioramenti rocciosi del golfo di trieste (da caressa et al., 2001 modificato). (a destra, 4b) fotografie delle varie tipologie morfologiche. (left, 4a) the main morphological features of the rock outcrops in the trieste gulf (from caressa et al., 2001 modified). (right, 4b) photographs of the different morphological typologies. a) b) 560 mente tabulari (con quattro sottoclassi; da a a d, complessivamente 89%), a panettone (e, 1%) e pinnacolari (f, pari al 10%). la classe tabulare è stata suddivisa ulteriormente a seconda della disposizione rispetto al fondale e alle fatturazioni presenti (apicale su alti morfologici, intensamente fratturato con nucleo più esteso, compatto e tondeggiante) nelle tre forme b1 (27%), b2 (10%) e b3 (36%; fig. 5); mentre le tipologie c (6%; affioramenti inclinati), d ( circolari , abbinati a pinnacoli; 9%); ed e (1 %; panettoni) e, infine f (10 %; pinnacoli). l’indagine in immersione ha confermato quanto riportato da studi precedenti (stefanon, 1967; braga & stefanon, 1969; stefanon & mozzi, 1972; stefanon & mozzi, 1973; newton & stefanon, 1975; newton & stefanon, 1976; boldrin, 1979), ovvero il ricoprimento organogeno da parte d’individui costruttori (lithophillum, peyssonelia e lithothamnium) di un substrato solido sabbioso, non sempre ben visibile, ma quando rilevabile caratterizzato da una marcata stratificazione piano parallela, resa più evidente da fenomeni d’erosione selettiva. si è constatato, inoltre, che i litosomi sono incisi da profonde fenditure per l’intero spessore e che assumono andamenti quasi sempre ortogonali alla stratificazione. l’origine di tali fenditure sembra essere recente e da ricercarsi nell’azione erosiva delle correnti di fondo che scalzano alla base la roccia cementata, determinando una prima fenditura e poi il crollo delle parti sospese. da queste indagini non è stato possibile e. gordini et al. fig. 5 – mosaico di sonogrammi a scansione laterale di un gruppo d’affioramenti di tipo “b3 tabulare”. mosaic lateral scanning echosouding diagram showing an outcrop group “ tabular b3” type. fig. 6 – operazioni di campionatura delle rocce (destra) e sezione di un campione (sinistra). rocks sampling (right) and sample section (left). definire la profondità del letto dell’affioramento che risulta annegato sui sedimenti del fondo. analisi eseguite sui campioni di roccia (in fase di perfezionamento) e sui sedimenti evidenziano una analogia mineralogica e granulometrica dei depositi cementati con le sabbie di piattaforma adiacenti. le rocce sono arenarie fini, grano o fango sostenute, con minimo cemento carbonatico, ricristallizzato (fig. 6). da un punto di vista paleontologico le rocce sono prive di macro e microfaune ad eccezione di pochi casi. al fine di verificare il radicamento di questi affioramenti rocciosi nel sottofondo e per indagare sulla loro possibile continuità con i depositi trasgressivi superficiali (del sistema tst) o con quelli più profondi (del sistema lst) è stata utilizzata la metodologia sub-bottom profile chirp (fig. 7). e’ emerso che la maggioranza 561i depositi cementati del ... fig. 7 indagine acustica sub-bottom profiler chirp (2-7 khz). (a) rappresentazione 3d; (b) mappa del fondale marino (prospezione con ecoscandaglio digitale); (c) profilo acustico (e interpretazione) eseguito in corrispondenza di due affioramenti rocciosi (a-b). il profilo evidenzia la tipica forma a panettone di questa tipologia morfologica d’affioramento. in particolare mostra una soluzione di continuità tra i due affioramenti rocciosi presenti, sottolineata dall’ottima penetrazione del segnale nella successione sedimentaria intermedia. i corpi rocciosi presentano radici estese all’interno della coltre sedimentaria superficiale; (d, e) profili acustici (e interpretazioni) eseguiti perpendicolarmente alla direzione di massimo sviluppo degli affioramenti rocciosi (c-d ed e-f ). i due transetti evidenziano molto bene la geometria tabulare degli orizzonti sedimentari presenti nell’area di indagine, interrotti solamente dalle tipiche lacune acustiche in presenza di corpi rocciosi superficiali (c-d). la presenza di riflettori acustici irregolari è determinata essenzialmente da accumuli di gas intrappolato all’interno dei sedimenti. sub-bottom profiler chirp (2-7 khz) survey. (a) 3d sketch; (b) seafloor map (digital echosounder survey); (c) sonar profile (and the interpretation) performed across two rock outcrops (a-b). the profile shows the typical “panettone – christmas sweet bread” shape of these rock outcrops. in particular a good continuity between the rock outcrops is shown. it is underlined by the good penetration of the signal within the stratigraphic sequence. the rocky bodies introduce wider roots inside the superficial sedimentary blanket; (d, e) sonar profile (and the interpretations) performed perpendicular to the direction of the rocky outcrops maximum development (c-d and e-f). the two profiles underline well the tabular geometry of the sedimentary section, locally interrupted by acoustic gaps due to surficial rocky bodies (c-d). the presence of irregular acoustic reflectors is determined by accumulations of gas within the sediments. degli rock outcrops a forma tabulare presentano una limitata potenza (ca. 1 m) e un ridotto o talvolta assente sviluppo radicale, ben visibile all’interno del materasso sabbioso riconducibile al sistema tst. le radici degli affioramenti quasi sempre si esauriscono al tetto dei depositi continentali del lst che si trovano a 30-40 cm dal fondo. anche gli affioramenti a forma di “panettone”, più radicati, sembrano prendere origine da questi depositi continentali con processi analoghi a quelli visti per gli affioramenti tabulari. il corpo sedimentario lst viene contraddistinto da facies acustiche contrassegnate da riflessioni prevalentemente piano parallele, variabili in ampiezza e frequenza, in cui i riflettori principali appaiono spaziati di alcuni metri e livelli decimetrici, indicanti superfici meno riflettenti. in questa coltre sedimentaria alluvionale si riconoscono orizzonti torbosi e una diffusa presenza di gas manifestata da evidenti lacune acustiche tipiche. in estrema sintesi, i dati fino ad ora raccolti portano a ritenere che almeno per alcuni di questi litosomi sembra accertata un’origine per cementazione dei clasti per ossidazione del metano contenuto nel sottosuolo. lo stanno a dimostrare le manifestazioni gassose che si rinvengono sulla loro verticale (bromboli), le sacche di gas individuate nel sottosuolo e la presenza di solfo batteri che si rinvengono al loro intorno (fig. 8). anche altri studi eseguiti nell’area (e anche in aree finitime, come il golfo di venezia e l’adriatico in generale) da autori precedenti hanno evidenziato la stessa genesi per alcuni affioramenti indagati. al momento però dall’analisi degli affioramenti del golfo di trieste non si arriva ad una certificazione analitica di questa genesi, in quanto le indagini sul cemento sono estremamente problematiche a causa della scarsità di materiale reperibile e da processare con i normali metodi della geochimica isotopica. rimane, comunque, la constatazione che non tutti gli affioramenti individuati sono connessi a sacche di gas riconosciute nel sottosuolo. a ciò si aggiunga che il gran numero di campi d’affioramenti sottomarini individuati, ognuno con diverse rocce singole, la loro diversità di forma, il loro scarso radicamento sul sottofondo marino, la coincidenza a volte con la presenza di mattes di posidonia oceanica morta e, a complicare ancora di più la situazione, l’analogia di alcune rocce con i livelli cementati dei suoli (pan), mentre per altre con componenti organogene, la similitudine con le attuali sabbie di piattaforma inducono a supporre una diversità di genesi di questi litosomi nell’ambito dello stesso ambiente marino e in quello continentale sottostante. non si esclude, pertanto, che oltre alla cementazione in loco di depositi continentali legati alla fuoriuscita di gas metano, originato probabilmente da processi di decomposizione delle torbe depostesi durante l’ultima glaciazione würmiana, altri possibili processi di cementazione precoce siano intervenuti nei depositi del sottofondo e fondo marino del golfo di trieste. in via del tutto preliminare si ritiene che questi processi possono essere ricercati in: • una cementazione di depositi sabbiosi marino-litorali, avvenuta all’interno dell’antico prisma sedimentario costiero e sulle antiche linee di riva; • una venuta a giorno, per erosione della coltre sedimentaria soprastante, di depositi alluvionali cementati inclusi nel materasso sabbioso della paleopianura tardiglaciale; • una cementazione dei depositi sottostanti le praterie di posidonia oceanica una volta abbondanti in questi mari e attualmente scomparse per cause ancora dibattute. le indagini programmate per il prossimo futuro dovranno dare risposta a queste ipotesi. 562 e. gordini et al. fig. 8 presenza di chiazze biancastre batteriche sul fondo marino in corrispondenza delle emanazioni gassose. photograph showing the presence of white bacterial mats on the seabed in an area of active gas seepage. bibliografia boldrin a. (1979) aspetti ecologici delle formazioni rocciose dell’alto adriatico. atti del conv. sc. naz. p.f. ocean. e fondi mar., 3, 1197-1207. braga g. & stefanon a. (1969) beachrock ed alto adriatico: aspetti paleogeografici, climatici, morfologici ed ecologici del problema. atti ist. ven. sc. lett. art. cxxvii, 351-359. caressa s., gordini e., marocco r.& tunis g. (2001) caratteri geomorfologici degli affioramenti rocciosi del golfo di trieste (adriatico settentrionale). gortania, 23, 5-29. colantoni p., fanzutti g.p. & marocco r. (1985) geologia della piattaforma adriatica . p.f. oceanografia e fondi marini, 49-85. colantoni p., gabbianelli g., ceffa l. & ceccolini c. (1998) bottom features and gas seepages in the adriatic sea . estratto da: v international conference on gas in marine sediments, 28-31. conti a., stefanon a. & zuppi g.m. (2002) gas seeps and rock formation in the northern adriatic sea. cont. shelf res., 22, 2333-2344. galassi p.& marocco r. (1999) relative sea-level rise, sediment accumulation and subsidence in the caorle lagoon (northern adriatic sea, italy) during the holocene. il quaternario, 12 (2), 249-256. gordini e., marocco r. & vio e. (2002) stratigrafia del sottosuolo della “trezza grande” (golfo di trieste, adriatico settentrionale). gortania, 24, 31-63. gordini e., caressa s. & marocco r. (2003) nuova carta morfo-sedimentologica del golfo di trieste (da punta tagliamento alla foce dell’isonzo). gortania, 25, 5-29. gordini e., ramella r., romeo r., deponte m. & marocco r., (in stampa) indagini acustiche sugli affioramenti rocciosi del golfo di trieste (adriatico settentrionale). gortania. jensen p., aagaard i., burke jr r. a., dando p. r., jorgensen n. o., kuijpers a., laier t., o’hara s. c. m. & schmaljohann r. (1992) bubbling reefs in the kattegat: submarine landscapes of carbonate-cemented rocks support a diverse ecosystem at methane seeps. mar. ecol. prog. ser, 83, 103-112. marocco r. (1991) evoluzione tardopleistocenica-olocenica del delta del f. tagliamento e delle lagune di marano e grado, (golfo di trieste). il quaternario, 4(1b), 223-232. marocco r., melis r., montenegro m.e., pugliese n., vio e. & lenardon g. (1996) holocene evolution of the caorle barrier-lagoon (northern adriatic sea, italy). riv. ital. pal. strat., 102 (3), 385-396. mizzan l. (1999) localizzazione e caratterizzazione di affioramenti rocciosi delle coste veneziane. primi risultati di un progetto di indagine. boll. mus. civ. st. nat. ven., 50, 195-212. newton r. & stefanon a. (1975) the “tenue de ciosa” area: patch reefs in the northern adriatic sea. mar. geol., 8, 27-33. newton r. & stefanon a. (1976) primi risultati dell’uso simultaneo in alto adriatico di side scan sonar, subbottom profiler ed ecografo. mem. biogeogr. adriat., 9, suppl., 33-60. stefanon a. (1967) formazioni rocciose del bacino dell’alto adriatico. atti ist. ven. sc. lett. arti, 125, 79-85. stefanon a. (1979) gli affioramenti rocciosi dell’alto adriatico: considerazioni sulla loro distribuzione, struttura ed evoluzione, nel contesto della problematica del bacino. conv. pf oceanografia e fondi mar., roma, 1233-1242. stefanon a. (1984) sedimentologia del mare adriatico: rapporti tra erosione e sedimentazione olocenica. boll. ocean. teor. appl., ii, 4, 281-324. stefanon a. (1985) marine sedimentology through modern acoustical methods: i. side scan sonar. boll. ocean. teor. appl., iii, 1, 3-38. stefanon a. (1980) the acoustic response of some gas-charged sediments in the northern adriatic sea. bottom interacting ocean acoustics conference, saclant asw centre, la spezia, 73-84. stefanon a. & mozzi c. (1972) esistenza di rocce organogene nell’alto adriatico al largo di chioggia. atti ist. ven. sc. lett. arti, 130, 495499. stefanon a. & mozzi c. (1973) rock outcrops in the nortern adriatic sea. scien. div. inter, 203-206. stefanon a. & zuppi g.m. (2000) recent carbonate rock formation in the northern adriatic sea. hydrogèologie, 4, 3-10. 563i depositi cementati del ... ms. ricevuto l’8 giugno 2004 testo definitivo ricevuto il 23 novembre 2004 ms. received: june 8, 2004 final text received: november 23, 2004 imp.savelli& la città di forum sempronii e i suoi rapporti con il paesaggio attuale: una discussione basata su evidenze geologico-geomorfologiche e archeologiche daniele savelli1, mario luni2 & oscar mei2 1istituto di geologia, università degli studi “carlo bo”, campus scientifico, loc. crocicchia, 61029 urbino d.savelli@uniurb.it 2istituto di archeologia e storia dell’arte antica “sandro stucchi”, università degli studi “carlo bo”, via del balestriere, n. 2, 61029 urbino – m.luni@uniurb.it riassunto: savelli d., luni m. & mei o., la città di forum sempronii e i suoi rapporti con il paesaggio attuale: una discussione basata su evidenze geologico-geomorfologiche e archeologiche. (it issn 0394-3356, 2004). forum sempronii sorgeva su un vasto terrazzo del metauro a una distanza variabile da 200 a 700 m ca. dall’attuale alveo. sui lati meridionale e occidentale le mura correvano sul ciglio delle scarpate del terrazzo stesso, mentre sul lato settentrionale correvano alla base del versante collinare; più problematica la posizione sul lato orientale, non corrispondente ad alcun elemento dell’attuale fisiografia. alcuni caratteri geomorfologici e depositi recenti mettono in evidenza modificazioni minori, ma importanti, e permettono un tentativo di ricostruzione dell’assetto fisiografico del locale paesaggio in epoca romana. in particolare, due erano gli elementi principali che caratterizzavano il paesaggio in questo periodo: 1. il fiume verosimilmente scorreva sul lato sud a ridosso della cinta muraria, come è testimoniato da un vasto meandro abbandonato, con forme freschissime e depositi contenenti frammenti di terrecotte elaborati dall’azione fluviale all’ingresso del meandro. 2. il lato orientale era con tutta probabilità bordato da un fosso oggi quasi interamente colmato e del quale restano tuttora la sola porzione iniziale, sul versante, e terminale, sulla scarpata del paleomeandro. tale configurazione permetterebbe di superare alcune apparenti incongruenze fra l’attuale paesaggio e le primarie necessità sia difensive che di approvvigionamento idrico e di viabilità dell’insediamento romano. abstract: savelli d., luni m. & mei o., the town of forum sempronii and its relations with the contemporary landscape: a discussion based on geologic, geomorphologic and archaeological evidence. (it issn 0394-3356, 2004). the roman town of forum sempronii, founded between 132 and 126 b.c., is set near the modern village of san martino del piano, ca. 2 km to the east of fossombrone. the ancient settlement rests on the flat surface of a wide upper-pleistocene terrace of the metauro river, ca. 20 m above the modern stream. at least three sides of the roman town walls took advantage of geomorphologic elements. indeed, they were against the foothill to the north; to the west they ran along the edge of a steep scarp on the left of fosso della conserva (a small left-tributary stream of the metauro river), and they rose southwards on the edge of the pleistocene terrace. the eastern side is more problematic as regards both its true position and its relation to some specific landform: in all probability it developed along the bank of a no longer recognisable gully. one of the most important features of the modern landscape in the vicinity of the archaeologic site is a roughly flat-bottomed, broad semicircular depression representing a pronounced relict meander of the metauro river. it is entrenched into the upper pleistocene terrace unit and bounded to the north by the terrace scarp on which the southern wall of the roman town was built. hence, the scarp enclosing the abandoned meander separates the upper-pleistocene terrace alluvium from the holocene one: it is well-preserved, with a sharp upper edge and scarce colluvium/debris accumulation at the toe. furthermore, the abandoned metauro river channel is still well recognisable along almost all the scarp toe. the excellent preservation of such landforms hints at quite a recent cut-off of the meander neck and abandonment of the previous course. moreover, the very occurrence of rounded roman bricks and tiles in alluvial deposits at the mouth of the abandoned meander hints at a recent fluvial activity on at least a sector of the relict fluvial bend. finally, maps dating back to 16th –18th century show that the meander at issue was already inactive and only minor adjustments of the fluvial course did occur at its mouth. on the basis of these considerations, and since important modifications of fluvial-channel patterns in nearby areas can be ascribed to late roman-early medieval times, we can speculate that the “roman” metauro river flowed through the abandoned meander of today, close to the southern walls of the town. the presence of a large fluvial channel just close to the town walls would have enhanced their defensive effectiveness. indeed, its vicinity to the river would have made the southern side of the town the more defensible one as well as a preferential way for watering. moreover, the presence of an active channel at the foot of the scarp would have been able both to improve gully development and to sustain existing gullies free from debris-filling, thus allowing ditches similar to the one which has been hypothesized to border the eastern wall of the town to be sustained. on the contrary, the meander cut-off and the abandonment of the previous river course would have been able both to enhance the filling-up of such gullies and to accelerate their extinction. parole chiave: : modificazioni fluviali, geo-archeologia, forum sempronii, fiume metauro. keywords: fluvial modifications, geo-archaelogy, forum sempronii, metauro river. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 185-193 1. premessa le relazioni dell’uomo con l’ambiente nei suoi vari aspetti e con l’ambiente "geomorfologico" (sensu panizza, 1992, pag. 344) in particolare, sono sempre legate da stretti vincoli di reciprocità e interdipendenza. infatti, in accordo con mansuelli et al. (1957, p. 200) “la capacità selettiva dell’uomo riconosce nell’ambiente in cui si svolge la vita i fattori preferenziali per stabilire la propria sede: clima, possibilità di rifornimenti, sicurezza”. proprio il concorrere di tutti questi fattori va a costituire il cosiddetto optimum ecologico. in tale contesto i fiumi, in quanto vie naturali, oltre che luoghi ricchi d’acqua, hanno costituito i primi assi di sviluppo del 186 d. savelli, m. luni & o. mei popolamento umano. pertanto, la presenza di fiumi, insieme a quella di sorgenti, è sempre stato un elemento determinante per la scelta della località destinata a essere sede di un abitato, sicché è rarissimo il caso di abitati che ne siano lontani. inoltre, l’intrecciarsi di canali naturali spesso incassati fra aspre ripe d’erosione, isola settori di territorio che, oltre a mantenere i vantaggi della vicinanza al corso d’acqua, risultano difesi sia dall’irruenza distruttiva delle piene che da eventuali nemici. le trasformazioni del paesaggio, specie quello fluviale, avendo tempi e ritmi paragonabili con quelli dei cambiamenti storici e culturali (cfr. panizza & piacente, 2003, p.216), possono produrre interazioni e legami talora complessi che rendono necessario un approccio integrato sia per la comprensione degli eventi che per poter delineare i tratti evolutivi di un territorio. in particolare, le trasformazioni recenti e talora intense del territorio obliterano spesso i caratteri fisiografici originari, collocando apparentemente gli insediamenti al di fuori del loro contesto “naturale” e ponendo questioni sul perchè della scelta di ubicazioni apparentemente illogiche. nell’area nord-marchigiana, ne sono un esempio lo spostamento del foglia a pesaro (luni, 1995) e il forte avanzamento della linea di riva a fano (elmi et al., 1994; luni, 2000, pp. 75-77). altrettanto importante è la ricostruzione degli antichi paesaggi e della loro evoluzione al fine di dirimere questioni storiche particolari come ad esempio, nell’area considerata (savelli & nesci, 1994; nesci & savelli, 2002), la controversa questione dell’ubicazione della famosa battaglia del metauro (cfr. luni 2002 cum bibl.). anche forum sempronii mostra apparenti incongruenze fra paesaggio attuale e collocazione del nucleo insediativo o di parti di esso, ponendo l’accento su possibili modificazioni ambientali successive all’abbandono della città. in tale ambito, lo scopo della presente nota è quello di affrontare una discussione integrata di elementi geologico-geomorfologici e archeologici. l’obiettivo è infatti quello di fornire un contributo alla soluzione del problema della evoluzione recente del tratto della val metauro sul quale tale città sorgeva (fig. 1) e mettere in evidenza, in particolare, eventuali migrazioni fluviali o scomparsa di linee di drenaggi preesistenti. 2. elementi archeologici forum sempronii fu fondata, in un’area già frequentata in età preromana, tra 133 e 126 a.c., probabilmente in seguito all’intervento di caio sempronio gracco, la cui presenza nel territorio è documentata da un’iscrizione (cil, i2, 719) rinvenuta nel ‘700 a san cesareo, nella collina di monte giove, presso fano. il cosiddetto “cippo graccano” ricorda l’attività della commissione triumvirale nominata per l’applicazione della lex sempronia del 133 a.c., che portò a una riorganizzazione dell’ager publicus attraverso la divisione e la distribuzione del terreno in lotti (centuriazione). forum sempronii divenne municipium nel corso del i secolo a.c., fu ascritto alla tribù pollia ed è menzionato da strabone (v, 2, 10), plinio (naturalis historia, iii, 113) e tolomeo (iii, 1, 46), oltre che dagli itineraria . contraddistinta da una fiorente comunità cristiana già dalla fine del iv o agli inizi del v secolo d.c. e sede vescovile (vernarecci, 1903, pp. 97-116) la città subì gravi danni durante la guerra greco-gotica del 535-553 d.c. successivamente, la maggior parte degli abitanti si spostò su un vicino colle, più facilmente difendibile, originando così il centro di altura che si sviluppò in età medievale e rinascimentale col nome di fossombrone (v. fig. 1). la città originaria venne così quasi completamente abbandonata, ma il nuovo insediamento, pur con alcune modificazioni dovute al trascorrere dei secoli e al mutare della lingua, ne ereditò il nome (luni, 2001, p. 16). il sito dell’antico municipium fu localizzato fin dal xv secolo sulla vasta piana sulla quale sorge l’attuale frazione di san martino del piano, circa 2 km a est di fossombrone (fig. 1), in seguito ai rinvenimenti di manufatti che ripetutamente si verificavano nel corso dei lavori agricoli (vernarecci, 1903, pp. 30-34; mercando, 1983, pp. 83-84; gori & luni, 1983, pp. 9196). la presenza della via flaminia, aperta intorno al 220 a.c., oltre ad aver condizionato l’assetto viario della città, di cui andò a costituire il decumanus maximus, ha rappresentato anche la principale causa di sviluppo economico, almeno per i primi due secoli dell’impero. i limiti dell’area urbana, riconosciuti con sicurezza fig. 1 il tratto inferiore della valle del fiume metauro con l’ubicazione dell’area in studio. the lower metauro river valley and location of the study area. su tre lati, presentavano mura che sfruttavano elementi geomorfologici di notevole rilevanza (figg. 2, 3, 4): a nord si appoggiavano al piede del versante collinare, a ovest correvano lungo il ciglio della ripida scarpata incisa in sinistra idrografica dal fosso della conserva (modesto affluente di sinistra del metauro), a sud si ergevano sul ciglio della scarpata di un vasto terrazzo pleistocenico del metauro stesso. in particolare, in corrispondenza del fosso della conserva il montecchini (1879, p. 94) vide “dalle alte sponde, sporgere dal terreno le fondamenta squarciate di molti fabbricati, e la sezione di pavimenti delle stanze e del selciato delle strade..”, testimoniando così l’erosione delle sponde dovuta al regime torrentizio del corso d’acqua (gori & luni 1983, p. 93). il confine orientale, più problematico sia come ubicazione che come corrispondenza con particolari elementi morfologici, correva verosimilmente sul margine di un fosso attualmente non più riconoscibile. 187la città di forum sempronii ... sono state identificate necropoli di una certa consistenza sia a ovest, oltre il fosso della conserva, sia a est dell’abitato (fig. 2), con rinvenimenti di monumenti sepolcrali utili per delimitare l’estensione dell’antica area urbana. tombe “alla cappuccina” (con letto e copertura di tegole e pochi oggetti di corredo) di piena età romana sono state segnalate proprio sul settore più orientale della scarpata che delimita la città verso sudest (dato inedito, comunicazione orale del prof. g. gori). probabili tratti della cinta muraria sono attualmente visibili lungo il lato meridionale (fig. 2, n. 9), così come i resti di due torri quadrangolari in opus quadratum, inglobati nelle fondazioni di case coloniche (gori & luni, 1983, pp. 92 e 103, fig. 2, n. 16), mentre un tratto di mura in opus tumultuarium (risalente alla metà del vi secolo d.c., direttamente legato alle vicende della guerra greco-gotica) con torre circolare, è stato messo in luce proprio sul lato orientale (fig. 2, n. 11). sempre su fig. 2 pianta di forum sempronii: 1) edificio termale; 2-3) ambienti con impianti di riscaldamento a ipocausto; 4) ambiente con colonne; 5) domus con mosaici; 6) muri; 7) basolato della via flaminia; 8) probabile basilica civile; 9) mura urbiche; 10) trincea di scavo; 11) torre circolare, vi secolo d.c.; 12-17) villa rustica; 13) deposito di anfore; 14-15) resti di edificio; 16) torri quadrangolari in opus quadratum; 18) vie interne all’abitato. plan of forum sempronii: 1) baths; 2-3) rooms with heating system (hypocaust); 4) room with columns; 5) domus with mosaics; 6) walls; 7) via flaminia; 8) probable civil basilica; 9) city walls; 10) trench; 11) round tower, vith century a.d.; 12-17) villa rustica; 13) amphorae’s find; 14-15) building ruins; 16) quadrangular towers in opus quadratum; 18) town street. 188 questo versante strutture forse pertinenti a una porta urbica sono state messe in luce nel 1806 e poi ricoperte, nello stesso luogo in cui il 3 ottobre 1603 si rinvenne un’iscrizione menzionante la porta gallica (cil, xi, 6136; vernarecci 1903, pp. 34-35; gori & luni 1983, p. 103). l’abitato si presenta dunque esteso per circa 35 ettari, con impianto viario a scacchiera, caratterizzato da strade parallele e perpendicolari tra loro che si incrociano ad angolo retto (fig. 2). dal 1974 sono in corso scavi regolari da parte dell’istituto di archeologia dell’università di urbino, che hanno permesso di individuare e mettere in luce un edificio termale, un tratto urbano della via consolare flaminia e tratti di altre vie interne all’abitato, rendendo così possibile il riconoscimento di almeno un intero quartiere di abitazione rettangolare (insula) di due actus per tre (ca. 70x105 m, luni, 2001, pp. 11-16; luni, 2003). un problema ancora insoluto per quanto concerne il percorso della cinta muraria è quello riguardante i limiti meridionale e orientale della città. a sud infatti le strutture difensive correvano lungo il “ciglio tattico” costituito dalla ripida scarpata attualmente distante da ca. 200 m a ca. 700 m dall’alveo attuale del fiume metauro. la vasta depressione semicircolare che qui si nota (figg. 3, 4) è una delle caratteristiche più salienti del locale paesaggio e, come verrà evidenziato meglio in seguito, è da collegarsi a un meandro abbandonato dal metauro in epoca abbastanza recente. questa particolare forma è stata discussa già dal vernarecci (1903, p. 78) il quale, affermando che in tale area “l’acqua, certo, vi sarà stata introdotta” rigetta tuttavia una precedente, suggestiva ipotesi del morosini, il quale, nelle parole del vernarecci stesso, vedendo l’area “così formata da potere accogliere parte dell’acqua del metauro e averne un lago artificiale per ludi e per pugne navali, immaginò che ivi a’ tempi romani fosse una naumachia”. 3. aspetti geologici e geomorfologici la città romana sorge sulla superficie di un vasto terrazzo della valle del fiume metauro (fig. 3), circa 20 m al di sopra dell’attuale alveo. sui lati sud-occidentale e sud-orientale il perimetro della città coincide con il bordo di scarpate fluviali/fluvio-torrentizie, mentre sul lato nord-occidentale corre alla base del versante di sinistra della valle. il lato nord-orientale attraversa invece la superficie pianeggiante del terrazzo senza alcuna fig. 3 schema geomorfologico e distribuzione dei depositi continentali quaternari nel territorio di forum sempronii. geomorphologic sketch and distribution of quaternary continental deposits in the forum sempronii area. d. savelli, m. luni & o. mei 189 correlazione con elementi dell’attuale fisiografia. l’attuale metauro scorre in direzione circa e-w (fig. 3), allontanandosi progressivamente dalla scarpata fluviale che segna il margine sud-orientale della città, a orientazione circa sw-ne. la città poggia su alluvioni terrazzate prevalentemente ghiaiose (figg. 1, 3, 4), ben correlabili su base morfostratigrafica al "3° ordine" (e.g. savelli et al., 1984; nesci & savelli 1991a, 1991b) dei terrazzi della letteratura tradizionale. tale attribuzione è supportata anche da alcune date (radiocarbonio) relative ad aree non lontane dal sito considerato (alessio et al., 1987; calderoni et al., 1994) che, seppure ante quem, permettono comunque di inserire l’unità esaminata nel quadro delle fasi di terrazzamento note per i fiumi marchigiani (cfr. nesci et al., 1995) e riferirne i depositi al pleistocene superiore. alle spalle della scarpata principale, la superficie del terrazzo pleistocenico è stata rimodellata in modo più o meno intenso dal metauro (fig. 3), come sottolineano (cfr. savelli et al., 1984; nesci & savelli 1991a) sia la blanda inclinazione della superficie del terrazzo verso l’attuale alveo, sia varie scarpate minori e/o semplici rotture di pendio spesso associate a tracce di alvei relitti sinuoso-meandranti. come è logico aspettarsi, le tracce in superficie dei paleoalvei si interrompono all’altezza della città romana, fornendo così un elemento morfologico aggiuntivo, utile alla perimetrazione dell’area archeologica. la scarpata del terrazzo principale è costituita in certi punti da sole alluvioni, in altri alla sommità da alluvione e al piede da roccia in posto. queste differenze, dovute all’irregolarità del substrato, caratterizzato da depressioni alternate a rilievi sepolti (cfr. nesci & savelli 1991a), si riflettono sullo spessore della coltre alluvionale, variabile da minimi di 5÷6 m (p. es. in corrispondenza dell’angolo sud-occidentale della città romana) a oltre 20 m (p. es. scarpate in sponda destra, di fronte alla città). verso sw il substrato roccioso, affiorante sia sulle scarpate dei terrazzi che sul versante collinare, è costituito dai termini pelitico-arenacei della formazione marnoso-arenacea (tortoniano superiore); nel settore centrale compare la formazione gessoso-solfifera (messiniano inferiore-medio), qui rappresentata da marne tripolacee con potenti banchi di calcare di base (cfr. savelli & wezel, 1978); verso ne affiorano facies prevalentemente argilloso-marnose della formazione a colombacci (messiniano superiore). fra l’orlo della scarpata principale e i terrazzi più recenti che coprono con una certa continuità il fondovalle, si riconosce una serie di terrazzi minori, di ampiezza piuttosto modesta (n. 6 in figg. 3, 4). questi, posti a quote di 12÷15 m sull’alveo attuale e corrispondenti ad accumuli alluvionali di 5÷7 m di spessore, ove presenti, interrompono la continuità morfologica della scarpata principale, segmentandola. le corrispondenti unità alluvionali, poggiano sia sulle rocce del substrato (a sw della città romana) che sulle ghiaie del pleistocene superiore e i loro spessori, relativamente consistenti, esprimono una fase di aggradazione minore che va a interrompere temporaneamente il progressivo approfondimento fluviale. questo evento, di difficile inquadramento cronologico, potrebbe riferirsi a un olocene relativamente antico o, addirittura, alla parte fig. 4 sezioni schematiche mostranti la morfologia dell’area esaminata e i rapporti fra i depositi continentali quaternari rappresentati in fig. 3. i numeri sono gli stessi di fig. 3. schematic profiles elucidating the morphology of the study area and the relations among the quaternary continental deposits represented on fig. 3. explanation of numbers on fig. 3. la città di forum sempronii ... 190 finale del pleistocene superiore. in entrambi i casi, tuttavia, la natura prevalentemente ghiaiosa dei depositi, piuttosto disorganizzati e con elementi anche molto grossolani, li rende difficilmente comparabili con i depositi fini che caratterizzano analoghe fasi minori di aggradazione in vari corsi d’acqua delle marche centromeridionali (cilla et al., 1996 cum bibl.). il margine sud-orientale della città corre sull’orlo della scarpata principale del terrazzo pleistocenico, interrotta da un lembo del terrazzo minore sopra descritto nella sua sola estremità sud-orientale. ai piedi della scarpata, a 5-8 m al di sopra dell’attuale alveo (ca. 15÷12 m al di sotto della piana pleistocenica), si apre un’ampia piana fluviale olocenica che descrive un ampio anfiteatro naturale (fig. 5). la presenza di un modesto rilievo che si erge nella porzione centro-meridionale di questa piana, conferisce alla stessa un aspetto in pianta a ferro di cavallo, troncato verso sud dall’attuale alveo del metauro (fig. 3). si tratta di un esempio particolarmente esplicativo di meandro abbandonato, la cui evoluzione ha condotto dapprima alla formazione di uno strettissimo collo in corrispondenza di alcuni banchi di calcare di base, particolarmente resistenti, poi al taglio del collo stesso, con conseguente abbandono dell’antico tracciato e isolamento di un “testimone” roccioso ricoperto da lembi alluvionali di varia età (figg. 3, 4). dal punto di vista morfologico, la piana corrispondente al meandro in oggetto si raccorda con una serie di terrazzi minori distribuiti sull’intero fondovalle dell’area esaminata a quote di 4÷8 m sull’alveo attivo e costituiti da corpi alluvionali molto sottili (2÷3 m) variamente sovrapposti o incastrati. questo particolare assetto (cfr. fig. 6), collegato a modestissime scarpate o semplici irregolarità osservabili sulla superficie dei depositi (fig. 3), testimonia complessi e ripetuti episodi di cut-and-fill e modeste, ma ripetute migrazioni laterali dell’alveo in tempi molto recenti. alcuni affioramenti sulla sponda di sinistra del metauro, in corrispondenza dell’imbocco del meandro abbandonato e affioramenti oggi non più visibili al suo sbocco, mostrano una significativa frequenza di frammenti di terracotta romana (mattoni e tegole) arrotondati dall’elaborazione fluviale e associati alle ghiaie fluviali embriciate (fig. 6.2). questo testimonia da un lato il rimaneggiamento di materiali provenienti da ville rustiche adiacenti all’antica città (depositi a monte) e forse dalla città stessa (depositi allo sbocco del meandro) e, dall’altro, una età da romana a post-romana di almeno una parte dei depositi. a cavallo dell’alveo attuale, si osservano infine depositi fluviali molto recenti, di età verosimilmente di poco anteriore agli anni ’50 (sulla base dei fotogrammi del volo gai 1955), sulla superficie dei quali abbondanti tracce di canali a indice di sinuosità relativamente basso si associano a meno frequenti resti di tracciati sinuoso-meandranti. 4. discussione e conclusioni la non corrispondenza fra importanti elementi dell’insediamento romano di forum sempronii e la fisiografia attuale del luogo pone vari interrogativi su eventuali modificazioni ambientali sopravvenute dopo l’abbandono della città. indiscutibilmente infatti, la perizia fig. 5 il meandro abbandonato con l’ubicazione della città romana. the abandoned meander and location of the roman town. d. savelli, m. luni & o. mei tecnica dei romani e la loro attenzione a ogni singolo elemento morfologico erano tali da ricavarne nella loro attività edilizia e, soprattutto, nelle opere di difesa il maggior utile possibile (adam 1990, cum bibl.). gli aspetti archeologici e quelli geologico-geomorfologici non sono tuttavia trattati congiuntamente da alcun studio interdisciplinare recente; la solo opera del vernarecci (1903, pp. 31-32), fornisce in nota lapidarie informazioni geologiche, dalle quali risulterebbe che “l’antica città era fabbricata su marne e ghiaie plioceniche”. in tale contesto, il confronto interdisciplinare fra i dati storico-archeologici e geologico-geomorfologici relativi all’area su cui sorge forum sempronii ci permette di delineare i caratteri morfoevolutivi del territorio. i dati ottenuti permettono anche di discutere e chiarire alcune problematiche relative ai legami fra l’antico insediamento e l’ambiente fisico del tempo e forniscono nuovi e stimolanti spunti di discussione e di indagine, come a seguito sintetizzato. 1. il tracciato del fiume metauro era con tutta probabilità differente dall’attuale: in particolare il fiume percorreva localmente un ampio meandro che, se attivo in epoca romana, avrebbe permesso alle acque di lambire il lato sud-orientale della città. il modestissimo dislivello rispetto all’attuale alveo e la freschezza delle forme legate al meandro abbandonato (scarpate poco rimodellate, depressione corrispondente al paleocanale ben preservata e scarsamente colmata, scarsità di detriti al piede nonostante le scarpate siano costituite da materiali degradabili) mettono in evidenza un abbandono piuttosto recente. l’abbandono, comunque, è senz’altro precedente al 16°-18° secolo, in quanto la documentazione disponibile mostra per tale periodo una situazione simile all’attuale. in particolare, la documentazione storica, testimonianze orali e le evidenze in foto area del volo gai del 1955 mettono in risalto una serie di oscillazioni minori, con parziale rioccupazione del tratto iniziale del meandro dal 18° secolo a tutta la prima metà del 19° secolo. una attività del canale in antico è avvalorata anche dalla distribuzione di resti archeologici, fra i quali le tombe di piena età romana osservabili in sezione sulla scarpata, ma non presenti sulla piana (prof. g. gori, comunicazione personale). in particolare, il parziale collasso di alcune tombe e l’abbondanza di frammenti di terrecotte, a luoghi blandamente smussati, lungo tutto il piede della scarpata, potrebbe indicare il proseguire di una accentuata erosione di sponda sul lato esterno del meandro anche in età relativamente tarda, forse anche con una blanda ridistribuzione verso valle dei materiali. conclusioni analoghe possono essere tratte dalle sottili sequenze alluvionali con ciottoli costituiti da tegole e mattoni di epoca romana osservabili sia all’imbocco del meandro estinto e documentate in figura 6, che allo sbocco dello stesso. inoltre, lo spessore di ca. 4÷5 m di alluvioni di età da presumibilmente romana a post-romana (cfr. fig. 6.1), evidenzia uno “svuotamento” almeno parziale del solco del meandro abbandonato durante le fasi di vita della città. l’attività del meandro in epoca romana, non è in disaccordo con quanto noto in letteratura per l’evoluzione recente dei tratti medio-bassi delle valli marchigiane. infatti, in queste aree, i tracciati meandranti, che caratterizzano la reincisione dei depositi alluvionali del pleistocene superiore (cfr. nesci & savelli, 1986; nesci et al., 1995 cum bibl.; coltorti, 1991 e 1997 cum bibl.) persistettero verosimilmente fin dopo l’epoca romana, dopo di che vennero soppiantati da canali intrecciati a causa soprattutto di una incisiva azione antropica che produsse una sensibile deforestazione con conseguente incremento dell’erosione del suolo (coltorti, 1997). a prescindere da questi elementi, la datazione della fase di attività e di abbandono del meandro al momento resta tuttavia non meglio precisabile. dal punto di vista archeologico, va infine rimarcato che la presenza di un canale fluviale attivo a ridosso delle mura avrebbe accresciuto notevolmente l’efficacia delle stesse, rendendo il lato sud della città quello meglio difendibile e avrebbe altresì facilitato l’approvvigionamento idrico. 2. il lato sud-occidentale della città correva lungo il ciglio della ripa d’erosione torrentizia che costituisce il fianco di sinistra del fosso della conserva. quest’ultimo è rimasto pressochè invariato; solo alcune strette incavature nella scarpata (elemento peraltro comune con la 191 fig. 6 le alluvioni all’imbocco del meandro abbandonato. 1 = veduta d’insieme mostrante le unità contenenti: a) sporadici frammenti arrotondati di terrecotte (deposito di età romana?); b) abbondanti frammenti arrotondati di tegole e mattoni romani (fase alto-medievale?); c) materiali non anteriori al 20° secolo; d) materiali degli anni ’50-‘60. 2 = particolare dell’intervallo b): la freccia indica un frammento di terracotta romana arrotondata dall’elaborazione fluviale. recent alluvium in the upstream termination of the abandoned meander. 1 = overall view displaying the units containing: a) rare rounded brick fragments (roman times?); b) abundant rounded roman brick/tile fragments (early medieval times?); materials not older than 20th century; c) remnants of years 1950-1960. 2 = detail of the unit b): the arrow indicates a fragment of roman brick rounded by river reworking. la città di forum sempronii ... scarpata fluviale sulla quale corre il lato sud-occidentale delle mura) possono indicare piccoli franamenti locali forse successivi all’abbandono della città, a luoghi connessi anche con l’erosione di sponda in corrispondenza di anse del ruscello (cfr. gori & luni 1983, p. 93). 3. il lato nord-orientale della città era con tutta probabilità bordato da un fosso oggi quasi interamente colmato. l’esatta posizione delle mura su questo lato è tuttora incerta: esse, infatti, attraversavano qui la superficie del terrazzo pleistocenico oggi completamente pianeggiante e privo di particolari elementi morfologici di riferimento, nè i dati archeologici permettono un preciso posizionamento. l’attenzione posta dai romani allo sfruttare elementi fisiografici e la necessità di una adeguata difendibilità, inducono comunque ipotizzare presenza di un antico fosso adiacente a questa porzione della cinta muraria. alcune evidenze geomorfologiche permettono di avvalorare questa tesi. alcuni fossi parzialmente colmati segmentano la porzione settentrionale della scarpata che circonda il meandro abbandonato (fig. 3). il più occidentale di essi cade circa sul prolungamento del confine nord-orientale della città. l’avvallamento si presenta oggi relativamente ampio e arrotondato a causa di un consistente riempimento detritico; il canale attuale è rappresentato da un piccolo fosso vistosamente rettificato e arginato, solo occasionalmente percorso da acque di precipitazione. tuttavia, questa situazione potrebbe essere ben diversa da quella che si poteva riscontrare quando il suo sbocco era lambito dal canale fluviale. in questa fase il fiume poteva agevolmente caricarsi degli apporti prevalentemente limoso-sabbiosi di questo minuscolo tributario, mantenendone sgombro sia lo sbocco che il tratto terminale. in più l’erosione di sponda, arretrando lo sbocco del fosso e abbreviando gradatamente il suo tratto terminale, avrebbe contribuito al mantenimento dei gradienti e favorito il perdurare di una efficace rimozione dei detriti lungo il fosso stesso. sul versante collinare retrostante, sempre sul prolungamento del margine nord-orientale della città, si osserva una piccola valle a orientazione nw-se, sede di ampi fenomeni franosi in parte attivi (fig. 3). la valle è oggi percorsa da un corso d’acqua a regime occasionale che, al suo sbocco sul terrazzo pleistocenico, ha prodotto una zona di accumulo relativamente vasta. l’irregolarità della superficie dovuta a modificazioni antropiche più o meno recenti e, forse, al seppellimento e/o aggiramento di antiche strutture murarie (legate alla necropoli), rendono poco chiara la forma di accumulo naturale, anche se questa è almeno in parte interpretabile come conoide, coalescente sui lati con l’ampia fascia colluviale che verso sw ricopre in parte anche le rovine romane. il segmento terminale del corso d’acqua, che appare regimato e deviato artificialmente verso est, termina oggi al margine della conoide, in direzione di una vallecola che incide la scarpata del terrazzo pleistocenico molto più a valle della città romana. nonostante sia quello principale, questo non è il solo canale presente nel luogo: un altro, più piccolo è tuttora osservabile circa 250 m più a ovest, proprio in corrispondenza di una torre recentemente portata alla luce e riferibile al vi secolo d. c. (fig. 2, n. 11). il canale attuale, fortemente rettificato dall’azione antropica, termina oggi al piede del versante collinare. le mappe catastali della prima metà del ‘900 ne mostrano tuttavia la prosecuzione, attraverso una canalizzazione artificiale con vari gomiti all’interno della città romana, almeno sino all’attuale strada statale. a prescindere da quest’ultimo tratto, il cui andamento può essere il risultato di deviazioni artificiali relativamente recenti, risulta invece piuttosto interessante il segmento iniziale. questo (fig. 3) è stretto fra accumuli di frana in parte tuttora attivi e proprio i vari movimenti franosi possono, con l’andar del tempo, aver occluso una vallecola più lunga e profonda dell’attuale. in definitiva, sul prolungamento verso monte del margine nord-orientale della città, esiste oggi una valle contenente almeno due canali “ciechi”, che in passato potevano raccordarsi con quello osservato sulla scarpata del meandro abbandonato e sopra descritto. non è da escludere che proprio il minore, anche se oggi quasi irriconoscibile, potesse percorrere il lato esterno della cinta muraria collegandosi all’alveo del metauro e costituire un elemento naturale che, seppur modesto, potesse essere sfruttato per delimitare il perimetro abitativo. ringraziamenti gli autori desiderano ringraziare il prof. giancarlo gori, ispettore onorario della soprintendenza archeologica delle marche per la zona di fossombrone, per le proficue discussioni e le utili informazioni riguardanti dati ancora inediti, e la biblioteca passionei di fossombrone, nella persona della dott.ssa antonella cesarini, per la sempre continua disponibilità dimostrata durante la ricerca. lavori citati adam j. p. 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(1997) human impact in the holocene fluvial and coastal evolution of the marche region, central italy. catena, 30, pp. 311-335. elmi c., fanucci f., nesci o., beer p. & pignocchi a. (1994) evoluzione della linea di riva dal f. reno al f. potenza (italia centrale). il quaternario, 7(1), pp. 305-310. gori g. & luni m. (1983) note di archeologia e topografia forosemproniense. picus, 3, pp. 87-113. 192 d. savelli, m. luni & o. mei luni m. (1995) topografia storica di pisaurum e del territorio. in: aa.vv., “pesaro nell’antichità”, marsilio, venezia, pp. 85-139. luni m. (2000) studi su fanum fortunae. quattroventi, urbino, 321 pp. luni m. (2001) statue di bronzo a forum sempronii e in città del versante medio adriatico, in luni m. & gori g. (eds.), “i bronzi di forum sempronii”, quattroventi, urbino, pp. 11-67. luni m. (2002) la battaglia del metauro: tradizione e studi. quaderni di archeologia delle marche, 11, 259 pp. luni m. (2003) forum sempronii–fossombrone. in: luni m. (ed.), “archeologia nelle marche. dalla preistoria all’età tardoantica”. nardini, firenze, pp. 190-192. mansuelli g.a., alfieri n., castagnoli f. (1957) geografia e topografia storica. enciclopedia classica, sez. iii, x (iv), sei, torino, pp. 185-307. mercando l. (1983) documenti d’archivio per forum sempronii. bollettino d’arte, 19, pp. 83-110. montecchini p. (1879) la strada flaminia detta del furlo e i luoghi da essa attraversati nel tratto da ponte voragine alla città di fano, pesaro, 143 pp. nesci o. & savelli d. (1986) cicli continentali tardoquaternari lungo i tratti vallivi mediani delle marche settentrionali. geogr. fis. dinam. quat., 9, pp. 192-211. nesci o. & savelli d. (1991a) lineamenti geomorfologici del terrazzo fluviale del "3° ordine" del bacino del metauro (marche settentrionali). geogr. fis. dinam. quat., 14, pp. 141-148. nesci o. & savelli d. (1991b) successioni alluvionali terrazzate nell'appennino nord-marchigiano. geogr. fis. dinam. quat., 14, pp. 149-162. nesci o. & savelli d. (2002) geomorfologia della piana del fiume metauro. in: luni m. (ed.), “la battaglia del metauro: tradizione e studi”, quaderni di archeologia delle marche, 11, pp. 11-20. nesci o., savelli d., calderoni g., elmi c. & veneri f. (1995) le antiche piane di fondovalle nell’appennino nord-marchigiano. in: castiglioni g. b. & federici p. r. (eds.), “assetto fisico e problemi ambientali delle pianure ialiane”; mem. soc. geogr. it., 53, pp. 293-312. panizza m. (1992) geomorfologia pitagora, bologna, 397 pp. panizza m. & piacente s. (2003) geomorfologia culturale pitagora, bologna, 350 pp. savelli d., bartole r. & moretti e. (1984) caratteristiche litostratigrafiche con l'ausilio del sismografo di un terrazzo alluvionale del fiume metauro a fossombrone (marche settentrionali). acta naturalia de "l'ateneo parmense", 20 (1), pp. 63-79. savelli d. & nesci o. (1994) alcuni caratteri geomorfologici del fondovalle nella media e bassa valle del metauro. in: baldelli g., paci e. & tomassini l. “la battaglia del metauro”, minardi editore, fano, pp. 161-180. savelli d. & wezel f.c. (1978) schema geologico del messiniano del pesarese. boll. soc. geol. it., 97 (1-2), pp. 165-188. vernarecci a. (1903) fossombrone dai tempi antichissimi ai nostri, volume primo. mem. pubblicate a cura del municipio di fossombrone, soc. tipografica g. staurenghi & c., fossombrone, 560 pp. 193 ms. ricevuto il 26 aprile 2004 testo definitivo ricevuto il 19 ottobre 2004 ms. received: april 26, 2004 final text received: october 19, 2004. la città di forum sempronii ... microsoft word 01_negri_lm05.doc available online http:/amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 25 (2), 2012, 81-89 mediterranean sapropels: a mere geological problem or a resource for the study of a changing planet? alessandra negri1, florence colleoni2 & simona masina2,3 1 dipartimento di scienze della vita e dell’ambiente, università politecnica delle marche, ancona (italy) 2 centro euro-mediterraneo per i cambiamenti climatici, bologna (italy) 3 istituto nazionale di geofisica e di vulcanologia, bologna (italy) corresponding author: a. negri <a.negri@univpm.it> abstract: sapropels are sediments rich in organic carbon occurring cyclically in the mediterranean marine records and whose origin has been matter of great debate during the last decades. while the first sapropels were found in eastern mediterranean sediments from the miocene period, in this paper we focus on the layers that were subsequently found in sediment cores of pliocene to quaternary age from the eastern mediterranean mostly. since the very beginning of the history of studies on sapropels, authors inferred that those levels, being interbedded as dark layers in more or less normal light “open marine” sediments, formed during short-lived but catastrophic alterations in mediterranean oceanographic conditions, probably linked to broader climate changes. in this paper, the main hypotheses regarding the origin of those sediments are described and we highlight the importance of sapropel records for the study of climatic and oceanographic variability in the mediterranean area in the context of global climate change. keywords: mediterranean sea, plio-pleistocene, sapropel, paleoclimate. 1. introduction more than 477 papers have been published in the last 40 years with the keywords ‘mediterranean sapropels’. publication frequency is plotted in fig. 1. the number of papers published over this time interval is highly fluctuating, and this evidences periods of high interest and moments of decline in the attention to the topic. in this paper, we will recall the main approaches to the sapropel issue and we will propose new challenges in the study of these objects that must be seen not only as a local geological problem, but as a resource for the understanding of our changing planet. 2. the historical record the occurrence of stagnation episodes in the mediterranean basins during quaternary was first predicted by bradley (1938), who proposed that sapropels were due to low sea level in the glacial mediterranean. though, no marine sedimentary evidence was available at that time to strengthen his hypothesis. later on, kullenberg (1952) discussed the problem of sapropel formation as related to interstitial salinity variations using the cores of the swedish deep sea expedition (1948). few years later, olausson (1961) argued that sapropels were deposited after cold periods of glacially lowered sea level (about 100 meters lower than at present); during these periods, communication between the western and eastern mediterranean became restricted through the straits of sicily, resulting in an increase of salinity in the eastern basins, notwithstanding the (eventual) increase in runoff and precipitation. at the same time, surface water temperature decreased by about four degrees centigrade, increasing the density of surface water and leading to a continual renewal of the bottom water mass (e.g. non-sapropel condition). during deglaciation, temperature and sea level rose, then water density tended to decrease near the surface, as a result of less saline water added from the atlantic through the western mediterranean. as this transgression persisted, sea level eventually reached the elevation of the sill at the bosporus (40 m), causing low-density water from the black sea to pour out into the aegean, further lowering the density of surface water of the eastern mediterranean. then, the combination of warm, low-density superficial water led to density stratification and to stagnation of bottom water and sapropel formation. this model has been subsequently variously discussed by several authors (e.g chamley, 1971; miller, 1972; ryan, 1972; nesteroff, 1973; mccoy, 1974; cita et al., 1973). however, olausson's classic glacio-eustatic model was not sufficient to explain all aspects of sapropel formation. during dsdp legs 13 and 42a (ryan et al., 1973; hsu et al., 1978) in the mediterranean sea, many sapropels were obtained from deep sea cores and stimulated researchers to find explanations for their origin. sigl et al. (1978) suggested that differing faunal and lithological characteristics within sapropelic layers of different ages were indicative of different mechanisms of sapropel formation. since according to brongersma-sanders (1957) bituminous rocks may be formed when “either the supply of oxygen to the lower water layers is excessively low (persistent stagnation), or the supply of dead plankton and other oxidizable material is extremely high (hypertrophy)”, sigl et al.1978 proposed that both mechanisms could have helped to explain the occurrence of negri a. et al. 82 sapropelic sediments in “preglacial” lower pleistocene and upper pliocene sediments recovered by dsdp leg 13 (ryan et al., 1973; cita et al., 1973), as well as others in miocene cores recovered by leg 42a (hsu et al., 1978). during the same dsdp leg 42a, the discovery of sapropelic sediments in the western mediterranean (kidd et al., 1978) proved that this phenomenon was not entirely restricted to the eastern basin as it was assumed at that time, therefore stimulating new hypothesis about the mechanisms of sapropel formation. from that time on, two main models, encompassing the earlier hypotheses, were proposed to explain sapropel deposition: the “stagnation/anoxia” and the “increased productivity” models. according to the stagnation/anoxia model, anoxic bottom conditions are caused by a strong stratification of the water column that prevents vertical mixing and oxygen supply to the bottom waters. the origin of this stratification was explained as being due to increased nile river runoff linked to the periodic intensification of the african-asian monsoons (rossignol-strick 1983, 1985) and, later, by increased rainfalls and river discharge along the northern part of the eastern mediterranean sea (cramp et al., 1988; rohling & hilgen, 1991). in this framework, sarmiento et al. (1988) proposed a reversal in the water flow circulation as the most effective way of increasing nutrient concentrations to the point where anoxia occurs. indeed, numerical studies on thermohaline circulation suggest that a weakening of the present-day anti-estuarine circulation can lead to the deposition of enough organic carbon to account, at least, for the formation of the youngest sapropels s5 (125 ka) to s1 (9 ka) (myers et al., 2000; stratford et al., 2000). in addition, more recently, bianchi et al. (2006) suggested that a weak thermohaline circulation, supplying oxygen only to the first 500 meters of the water column can cause the development of an anoxic blanket at the seafloor, when coupled with increased productivity in the euphotic zone. in the “increased productivity” model, sapropel deposition was linked to enhanced organic matter flux (calvert, 1983; calvert et al., 1992), since the present production of organic matter in the eastern mediterranean cannot account for the high values of organic carbon (toc) characterizing these layers (calvert, 1983). this view has been further supported by evidence of a significant increase of productivity at times of sapropel deposition revealed by paleo-productivity proxies, as barium and marine barite concentration (e.g., thomson et al., 1995, 1999; martinez-ruiz et al., 2000, 2003; gallego-torres et al., 2007). later on, after the pioneer phase when the scientific community argued that the above mentioned processes were mutually exclusive, another phase followed when some authors (rohling & gieskes, 1989, castradori, 1993; rohling, 1994; emeis et al., 1996; emeis et al., 2000a) proposed a mechanism resulting from the combination of the two processes: stratification and productivity increase could have been caused by an overall increase of nutrient input via river runoff. however, uncertainties still exist regarding the vertical extension of the anoxic/dysoxic layer in the water column and this layer has been described either as a large water mass extending below the mixed layer (murat & got, 2000; stratford et al., 2000), or as an “anoxic blanket” above the sediment/water interface (casford et al., 2003). regarding the increase of productivity several hypothesis have been proposed, the most intriguing being that of kemp et al. (1999) who infer the formation of diatom mats during summer seasons of prolonged stratification (resulting from a water density contrast produced by nile run-off). the rapid sinking of the mats at the beginning of autumn–winter wind mixing, then, is assumed to produce a massive load of organic material to the sediments that consumed the available oxygen in the water column, creating anoxic conditions. from massbalance calculations, they argue that all of the organic carbon preserved in sapropels could have been supplied by diatoms. although the model can apply only to sapropels containing diatoms, the authors pointed out that the silica of these diatoms is highly soluble, and therefore that sapropels lacking diatoms may have once had them. on this basis, sancetta (1999) argued that the mechanism invoked for modern sapropels might therefore apply, as analogues, to other carbon-rich laminated strata, such as the 120-100 million year old mid-cretaceous black shales. a more refined hypothesis was proposed by meyers (2006) who suggested that increased continental run-off would have delivered abundant nutri fig. 1 papers published in the last 40 years having the word ‘sapropel’ in the title. mediterranean sapropels resource 83 ents that would have first stimulated algal productivity, magnified export of organic matter, and increased mid water oxygen demand. the combination of surface water dilution, which increased salinity stratification of the upper water column and thereby discouraged mixing and mid-water ventilation, and magnified oxygen-drawdown, would have intensified and expanded the oxygen minimum zone such that anoxia intruded into the photic zone. after photosynthetic cyanobacteria, green sulfur bacteria and chemosynthetic archaea became established, their primary productivity would have first augmented and then potentially would have superseded that of algae (e.g., kuypers et al., 2001; 2002 a,b). the shift to microbe-amplified productivity would have persisted until climate reverted to less wet conditions. sapropels occur all over the mediterranean area recorded after odp legs 160 and 161 (emeis et al., 1996; comas et al., 1996), which yielded the complete record of all the sapropels occurring in the last 5 million years, but they also outcrop on land sections (mainly in greece and italy). however, sprovieri et al. (2012), who investigated mechanisms of sapropel deposition in the mediterranean basin during the last 3.5 ma, showed that the water properties and circulation of both eastern and western mediterranean sea during the plio/pleistocene appear to be conditioned by the bathymetric control at the gibraltar and the sicilian sills. according to these authors, climatically driven intensity and characteristics of the western mediterranean deep water formation drive timings and modes of deposition of the organicrich layers in the alboran sea (odp sites 976 and 977). indeed, they claim that western sapropel deposition is generally not synchronous to precession minima, contrary to sapropel deposition in the eastern mediterrane fig. 2 from bottom to top: medstack detrended power in the 23k, 41k and 100k band (colleoni et al., 2012); sapropels (black, organic content > 2%) and grey layers succession from emeis et al. (2000) and lourens et al. (1996); total organic content (toc, %) of the black sapropels from the succession described above. the toc values are from odp 964, opd 966, odp 967 and odp 969. when different toc values were found in several cores for the same sapropel layer, the larger toc value was selected in order to better highlight the response of the mediterranean to the climate forcing. some of the black sapropels from lourens et al. (1996) does not have any toc value assigned because no analysis have been found. african monsoon index (in langley) based on rossignol-strick (1983). the vertical dotted line corresponds to the intensification of the northern hemisphere glaciation (~2.75 ma). negri a. et al. 84 an, and is largely related to the formation and vertical shift of oxygen minimum zones probably due to the rapid rise of the sicilian sill in the last 2 ma. therefore, sapropels occur cyclically, but not in phase, in the eastern and western basin. this hypothesis agrees with that proposed by rogerson et al. (2008) who demonstrated the older age (4-5 ky) of the most recent organic rich layers (orl) occurring in the western mediterranean, and hypothesized that it might be instead related more to the global sea level changes and resulted from a strong reduction in surface water density and shoaling of the interface between the intermediate and deep waters during the deglaciations. we can therefore see the deposition of eastern mediterranean sapropels in a framework of a reversed circulation. in fact, the present day circulation between the mediterranean sea and the atlantic ocean depend on the fact that evaporation exceeds precipitation. this way atlantic surface water, less saline and hence less dense, flows into the mediterranean. conversely, mediterranean salty waters flow at intermediate deep out of the basin. this type of circulation pattern is often referred to as anti-estuarine and is the opposite to the black sea circulation where fresh surface water flow out of the black sea to the mediterranean sea and salty mediterranean sea water flows through the bosphrous into the black sea. then, the black sea acts as a nutrient trap and is anoxic. in this view, trabucho-alexandre et al. (2012), argued that oceanic basins at the senile stadium of the wilson cycle (i.e. the cycle of opening and closing of an ocean basin due to plate tectonics) as presently the mediterranean is, can respond with black shales (sapropels) only if the circulation is estuarine, like in the black sea. then, the combination of sprovieri (2012) results and trabucho-alexandre (2012) hypothesis suggest that the eastern basin could be seen as a restricted basin due to the sicilian sill that hampers the flow of the levantine intermediate water and turns the eastern basin in a euxinic environment at the time of sapropel deposition. this somehow agrees with the hypothesis postulated by sarmiento et al. (1988), but overall, it suggests that, at least for the past 2 ma, western mediterranean orl and eastern mediterranean sapropels respond to different triggering mechanisms. this means that whatever is the mechanism triggering the sapropel deposition, those objects represent an important record to be studied in detail not only at regional scale, to understand which can be the relationship with the global ocean dynamic processes. 3. new clues only few attempts have been made to link what happened in the mediterranean region over the last 5 myr to coeval global climate change during that time period. sapropels or orl need not to be seen simply as regional geological problems. instead they are a precious source of information useful for understanding the evolution of our planet. in particular, the message contained within eastern mediterranean sapropels has to be interpreted in a global context: they are the consequence of extreme but episodic climate changes due to particular monsoonal and oceanic conditions that have favoured a very large production and deposition of organic carbon. the recent paper by colleoni et al. (2012) attempted to interpret the mediterranean oceanic changes as seen from the eastern mediterranean planktonic δ18o stack (hereafter medstack, lourens, 2004, wang et al., 2010) in a global context. the global and mediterranean climate changes over the last 5 ma are compared and linked through the spectral analysis of various marine records performed over the three orbital bands (100-kyr, 41-kyr related to obliquity and, 23+19-kyr related to precession). in the mediterranean planktonic signal, three periods were identified: until ~ 2.2 ma the signal is dominated by the 23+19-kyr frequency which is linked to the african monsoon influence in colleoni et al. (2012); from 2.2 ma to ~ 1.2 ma the signal is dominated by the 41-kyr frequency which is interpreted as the incursion of the polar influence into low latitudes; and finally, after the mid-pleistocene transition the signal is dominated by the 100-kyr frequency (fig. 6 in colleoni et al. 2012). how do the sapropels fit in the story? the pliopleistocene eastern mediterranean succession of organic-rich layers (emeis et al., 2000a, lourens et al. 1996, fig. 2) is based on odp sites 964, 966, 967 and 969 and on the capo rossello land section. this sapropel time-series is almost continuous and shows that, even if after 2.2 ma the medstack variability is driven by the 41-kyr frequency, the eastern mediterranean remains, however, paced by the african monsoon influence since the variance in the 23+19-kyr band remains strong all along the last 5 ma. nevertheless, some interruptions of the cyclical deposition of sapropels are observed and the longest one occurred during the socalled middle pleistocene revolution (mpt) at ~0.7 ma when the dominant frequency of the global climate variability changes from 41-kyr to 100-kyr. the interruptions are interpreted by colleoni et al, 2012 as an intrusion of the northern high-latitudes cooling signal into the low latitudes and therefore would have perturbed the periodic deposition of sapropels. in addition, in the first part of the pliocene, before the northern hemisphere glaciation (nhg) intensification, the occurrence of gray intervals (roughly: not well developed sapropels) suggests that the monsoon intensity was reduced during the early pliocene compared to the late pleistocene and that the monsoon was able to penetrate further into north in africa (larrasoana et al., 2003) only during strong precession minima. in the sapropel succession of fig. 2, we implemented the work of colleoni et al. (2012) which made a distinction between black sapropels, (organic carbon > 2% in weight following the convention of kidd et al., 1978) and grey layers showing a lower content of organic carbon. black sapropels seem to be quite scarce until ~3.4 ma, while after this time, grey layers (organic content < 2%) disappear almost completely (fig. 2). this suggests that marine productivity (or organic matter preservation) increased after 3.4 ma, this fact supported by the total carbon content (toc) values from the black sapropels succession described previously and reported in fig. 2. it shows that after 3.4 ma, the toc increased mediterranean sapropels resource 85 until reaching ~ 32% in weight during the intensification of nhg (~2.75 ma) and then gradually decreased until present-day. what caused such a toc increase ? as previously described, sapropels are assumed to form under particular oceanic temperature, salinity and productivity conditions, when a significant fresh water run-off reaches the mediterranean waters. whatever was the cause of sapropel deposition (either anoxia or productivity), based on that information, the issue is if we can directly relate the variations in toc to variations in continental run-off quantity and then to fluctuations in monsoon intensity alone. rossignol-strick (1983) tried to establish such a link by calculating an “african monsoon index” (fig. 2) for the last four glacial cycles based on the summer insolation anomaly between the equator and 23°n. they postulated that each sapropel layer corresponded to high monsoon index value (≥ 41 ly). to check whether this hypothesis was valid also for the oldest sapropels, we expanded their calculation for the entire plio-pleistocene period, and we point out if each large monsoon index value is associated with a grey layer or a black sapropel (fig. 2). nevertheless, each sapropel or grey layer does not always correspond to a high monsoon index value as calculated by rossignolstrick (1983). indeed, with this monsoon index, rossignol-strick (1983) assumed that a larger insolation input always triggered higher monsoon precipitation. but monsoon could be intense in terms of winds and/or precipitation. this implies that if sapropels were deposited under weak monsoon precipitation regimes, the mediterranean oceanic conditions (temperatures, salinity, oxygen) compensated somehow for the lower (but still higher than during “non sapropel” sedimentation) fresh water input. we can thus conclude that fluctuations in toc suggest that (i) either the monsoon precipitation started intensifying toward 3.4 ma and then weakened after ~2 ma, (ii) or that since 3.4 ma the sensitivity of the mediterranean waters (in terms of temperature, salinity and oxygen) to sudden warm climate fluctuations increased, and then decreased after 2 ma. this is consistent with the concomitant global climate cooling (lisiecki and raymo, 2005) which could have enhanced the sensitivity of the extra-tropical regions to brief and warm climate fluctuations. as a result, it is possible that this gradual global cooling increased the sensitivity of the mediterranean waters and of the monsoon system to large insolation peaks towards the nhg (~2.75 ma), allowing for particularly concentrated black sapropel deposition. in addition, khelifi et al. (2009) showed that the mediterra fig. 3 time series of the benthic stack lysieki and raymo (2005), co2 concentration in the vostock ice core (petit et al 2000) and occurrence of sapropels in the mediterranean sea. it is evident that the occurrence of sapropels corresponds to increases in co2 concentration. thickness of sapropel does not correspond to time duration. s1 and s5 are thicker to highlight the correspondence to the sharper co2 increase (circa 100 ppm) recorded after terminations ii and i, respectively. negri a. et al. 86 nean outflow intensified toward ~3.4 ma suggesting that changes in oceanic circulation occurred at this time. the relatively low value in toc during the pliocene could be due to the fact that the mean global climate state was warmer at this time and that consequently the monsoon intensity was almost constant and had only a limited impact on the stable mediterranean circulation. similarly, during the early pleistocene period, the mean global climate state evolved towards cooler temperatures. in that new climate context, all the system readjusted and despite the larger amplitude between glacial/interglacial periods that occurred at the end of the quaternary, the mediterranean became again less sensitive to the monsoon fluctuations as during the early pliocene period, or only during particularly warm interglacials (e.g. mis 11 and mis 5). 4. concluding remarks and perspectives there is still much to do in the study of sapropels. the relationship between toc, sapropels and the monsoon index of rossignol-strick (1983) is a further example that the mediterranean sea is adequate to study the high/low-latitude climate interplay, reflecting the dual response of the monsoon system to the mean global climate state and to regional climate constraints. the paper by colleoni et al. (2012) shows that after the intensification of the nhg (~2.75 ma), sapropel formation was influenced the waxing and waning of ice sheets in the northern high latitudes and therefore was sensitive to a north-south influence of climate, whereas the mediterranean dynamics were controlled by a east-west water mass exchange (discrepancies in the sapropels distribution between east and west). moreover, the medstack planktonic signal variability during the late pleistocene exhibits a sawtooth shape, as observed in many other records such as the benthic oceanic records or the speleothems timeseries, and is interpreted as a signature of the glacials/interglacials alternation. those observations raise several questions: (i) how can the global climate signal affect the mediterranean and how much does the flow exchange with the north atlantic at the gibraltar strait influence the mediterranean? (ii) what is the interplay between the monsoon signal and the mediterranean mean climate state? the need of exploring these questions also arises from other proxies that could be related to sapropel deposition such as, for example, the time-evolution of atmospheric co2 over the last 800 kyr. fig. 3 shows a detail of the last two glacial terminations (i and ii, 18-8 and 140-126 ka respectively) that correspond to abrupt increase of 100 ppm in the co2 atmospheric concentration in few thousands of years (vostok ice core, petit et al. 2000). at the end of the terminations, co2 reaches the maximum concentration, and simultaneously in the mediterranean sapropels s1 (9-6 ka) and s5 (midpoint age 124 ka) deposited. in addition, other minor interstadial fluctuations of atmospheric co2 are associated to sapropel deposition as well (fig. 3). is there a direct correlation between the large release of co2 in the atmosphere after a glaciation and the almost simultaneous production of organic carbon in the mediterranean? if yes, this could be seen as a local response of the systems to carbon removal from the oceanic water masses during the interglacial periods (co2 uptake in ocean increases during glacial periods). the large increase in atmospheric co2 is affecting the present-day world climate and there are few doubts that the temperature increase is related to this fact even if a direct correlation has not been demonstrated. understanding how the system reacts to co2 increase and, in the case of the mediterranean sea, tends to respond by taking up carbon that goes buried in marine sediments is an important issue that deserves an in-depth exploration by the scientific community. it is important to understand and investigate whether sapropels are part of a process that triggers co2 burial from global to regional scales and from millennial to decadal timescales. examples from the mesozoic era, when carbonate platforms were widespread, show that those platforms demise slightly preceded the deposition of black shales (cobianchi & picotti, 2001, chiari et al. 2007) evidencing a sort of balance in the carbon pump shifting from a carbonate system to a siliciclastic organic carbon-rich system in which the organic carbon content is due to primary producers that remove carbon either as organic carbon (corg) in the cells and also in the carbonate tests. in the mediterranean basin, carbonate platforms survived until the pliocene and the demise of some of them has been proven to occur, again, slightly before the deposition of sapropels (capozzi & picotti, 2003). numerical modeling of the biotic response under different atmospheric and oceanic scenarios can help to understand how quick the system responds, but so far only few models have been proposed (bianchi et al. 2006, meijer & tuenter, 2007) and their aim was restricted to analyze the phenomena at the regional scale, in order to explain the deposition of particular sapropels. instead, the exploration of the relationships among these sedimentary systems and the climate (primarily the monsoon influence) should be explored also at a global scale in order to understand the interplays between different regions in the world and the teleconnections between low and high latitudes. in conclusion, with this short review, we aim to stimulate the (paleo) climate community to expand the view of the mediterranean sapropels record as a product of the interplay of different global and regional processes and variability. the connections between all those processes have to be taken in consideration for understanding how the earth responds to climate changes at different timescales, to predict which changes can occur in a near future and how societies can adapt. acknowledgements the authors warmly thank j. trabucho-alexandre and n. ciaranfi for the careful revisions and important suggestions. we also acknowledge f. falcieri and a. sabbatini for useful comments on a early draft of the manuscript and alessio rovere for improving the english spelling. references bianchi d., zavatarelli m., pinardi n., capozzi r., capotondi l., corselli c., masina s. 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(2010) obscuring of long eccentricity cyclicity in pleistocene oceanic carbon isotope records. earth planet sc. lett., 290, 319330. ms. received: april 24, 2012 final text received: jun 8, 2012 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /all /binding /left /calgrayprofile (gray gamma 2.2) /calrgbprofile (srgb iec61966-2.1) /calcmykprofile (u.s. web coated \050swop\051 v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.4 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings true /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 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documenti pdf creati possono essere aperti con acrobat e adobe reader 5.0 e versioni successive.) /enu (use these settings to create adobe pdf documents suitable for reliable viewing and printing of business documents. created pdf documents can be opened with acrobat and adobe reader 5.0 and later.) >> >> setdistillerparams << /hwresolution [1200 1200] /pagesize [396.850 566.929] >> setpagedevice imp.diligenti& geomorphosites in the landscape of monti del furlo (northern marche apennines) antonio diligenti1, olivia nesci1 & daniele savelli1 1istituto di geologia, università degli studi “carlo bo”, campus scientifico, loc. crocicchia, 61029 urbino d.savelli@uniurb.it abstract: a. diligenti et al., geomorphosites in the landscape of monti del furlo (northern marche apennines). (it issn 0394-3356, 2005). three geomorphosites pertaining to the monti del furlo are taken into consideration. such area embraces the northernmost sector of an extended anticline ridge and is almost entirely included into a recently created natural national reserve. it is therefore clear how important it is in a naturalistic perspective. moreover, the cultural importance of this site is stressed by the roman via flaminia archaeological remains. this area also benefits from a great geologic/palaeontologic relevance, besides being really notable from a geomorphologic standpoint. in actual fact, the mountain ridge in hand is transversally cut by the furlo gorge, one of the most valuable and attractive geomorphosites in the marche apennines. furthermore, this important site can be associated with two other areas which, although not so remarkable as the furlo gorge, are worth improving as geomorphosites on account of their peculiar scientific, educational and scenic value. riassunto: a. diligenti et al., geomorfositi nel paesaggio dei monti del furlo (appennino marchigiano settentrionale). (it issn 03943356, 2005). il rilievo anticlinale dei monti del furlo è conosciuto principalmente per la famosa omonima gola incisa profondamente dal fiume candigliano attraverso i terreni giurassici-paleogenici della successione umbro-marchigiana. il territorio dei monti del furlo possiede un patrimonio geologico (peculiarità strutturali e stratigrafiche e famose località fossilifere), biologico (particolari specie floristiche e faunistiche) e geomorfologico (la gola e i paesaggi circostanti) che si integrano felicemente con paesaggi spettacolari, oltre a inserirsi in un contesto di notevole significato storico-archeologico (per esempio la via flaminia romana che attraversa la gola). i monti del furlo, anche per questi motivi, sono stati elevati al rango di riserva naturale statale al cui interno sono inseriti anche molti sentieri ed itinerari consigliati per l’osservazione delle caratteristiche naturali più rilevanti. la gola del furlo rappresenta un magnifico esempio di gola diaclinalica, forma molto caratteristica e abbastanza comune nei paesaggi appenninici marchigiani. per questo è stata scelta nell’ambito del progetto ministeriale “geositi nel paesaggio italiano” come geomorfosito da studiare, conservare e valorizzare. il presente lavoro vuole evidenziare il ruolo fondamentale che tale sito possiede nella comprensione dell’evoluzione del paesaggio marchigiano, in particolare per la genesi delle gole trasversali alle strutture tettoniche. al suo interno sono localizzati e descritti elementi geomorfologici caratterizzanti e peculiari che sono componenti chiave nella interpretazione del paesaggio e contribuiscono inoltre alla bellezza scenica del geomorfosito. nelle vicinanze della gola, sempre all’interno della riserva naturale, sono stati individuati altri due geomorfositi, la valle de “il buzzo” e la frana di ca i fabbri, che, oltre a costituire individualmente aree di rilevante interesse geomorfologico, contribuiscono contestualmente alla conoscenza dell’intero paesaggio dei monti del furlo. keywords: geomorphosites, furlo gorge, marche apennines. parole chiave: geomorfositi, gola del furlo, appennino marchigiano. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 203-211 1. foreword the anticline mountains of pietralata-paganuccio mts. (respectively 888 and 976 m high, here called “monti del furlo”, according to a local designation) are well-known primarily for housing the famous furlo gorge, a striking canyon deeply cut by the candigliano river (metauro river basin) across the jurassicpaleogene calcareous and marly-calcareous formations of the autochthon umbria-marche succession. the furlo gorge cross-cuts an anticline mountain ridge (figs. 1, 2): with the frasassi one (famous for its amazing caves above all), it is the best example of such puzzling landforms so characteristic of central italy. besides, it is one of the best geomorphosites (sensu panizza, 2001, i.e. “a site of special geomorphologic interest”) in the marche apennines. although impressive as well as crucial to the unravelling of plioquaternary evolution of this sector of the apennines, the gorge is not the sole geomorphologic peculiarity of the monti del furlo area. indeed, other valuable areas (worth improving as geomorphosites) do occur in its vicinity (cf. fig. 2), giving the gorge itself a surplus value. hence, in short, the area under discussion can be considered as encompassing more than one geomorphosite of greater or lesser geomorphologic relevance, each contributing to the geomorphologic evaluation of the whole. in turn, each geomorphosite comprises several individual, characterising landforms and/or landform associations of either scientific-educational importance or scenic relevance. more to the point, the monti del furlo area holds a major geologicpalaeontologic (e.g. structural and stratigraphic peculiarities and famous fossiliferous sites), naturalistic (e.g. 204 a. diligenti et al. fig. 1 geologic sketch of the northern marche region and location of the areas discussed in the text. schema geologico dell’area nord-marchigiana e ubicazione delle aree trattate nel testo. fig. 2 shaded relief of the monti del furlo anticline ridge with the location of the geomorphosites described in the text. the dotted line indicates the boundary of the study area. modello digitale della dorsale anticlinalica dei monti del furlo con l’ubicazione dei geomorfositi descritti nel testo. la linea puntinata indica il limite dell’area considerata nella presente nota. occurrence of floristic and faunal peculiarities), landscape (e.g. the gorge itself and the surrounding scenery) and historical-archaeological (e.g. the roman via flaminia remnants) relevance as well. these very essentials of both the furlo gorge and its environs have recently made this area become a national natural reserve (riserva naturale statale della gola del furlo), thereby arousing a great and renewed interest of both national and international communities. hence the monti del furlo area as a whole can be regarded as a “landscape unit” (cf. panizza & piacente, 2003, p. 264), where the geomorphologic constituents integrate into a wider naturalistic and historical-cultural geographic context. therefore, in the framework of the miur cofinanced project “the geosites of the italian landscape: research, evaluation and enhancement” the urbino research group, taking its cue from such basics and allowing for the global geosites inventory outlines (wimbledon, 1999), has accounted the monti del furlo as an area of primary geomorphologic relevance, proposing three individual geomorphosites and adopting this sector of the marche apennines as a sample-area for a targeted geomorphologic mapping. 205geomorphosites in the landscape ... 2. geologic framework the marche regional territory is characterised by a hilly coastal zone, where slightly deformed plioquaternary terrains predominate, merging to the southeast into a mountain chain area mostly corresponding to meso-cenozoic folded and thrusted formations of the autochthon umbria-marche apennines domain. it is characterised by two main ridges striking in a c.ca nw-se direction, the umbria-marche ridge (to the sw) and the marche ridge auct. (fig. 1), divided from each other by a broad topographic depression (cf. bisci & dramis, 1991 and references therein); several minor ridges either join the major ones flanks or stand on the inter-ridge depression (cf. fig. 1). both the major and the minor ridges consist of mesozoic-paleogene mainly carbonate and marly-calcareous units of the umbriamarche succession and correspond to asymmetric, mostly thrusted, ne-vergent anticlinoria (cf. deiana & pialli, 1994 and references therein). the monti del furlo area overlaps the northwestern termination of the marche ridge and consists of both the paganuccio and pietralata anticline mountains, divided by the furlo gorge (figs. 1, 2, 3). the paganuccio mt.-pietralata mt. (i.e. monti del furlo) anticline, characterized by an average n120 axial trend, is a slightly asymmetric box fold lacking in any clear evidence of major emergent thrusts on the forelimb. as a rule, the anticline, plunging both to the nw (anticline periclinal closure) and to the se (an axial depression), shows a marked local axial culmination in close proximity to the furlo gorge. the area at issue consists (cf. cecca et al., 1999) of carbonates, cherty carbonates, marls and calcareous marls of the umbria marche succession (figs. 3, 4), unconformably covered by a discontinuous and relatively thin mantle of quaternary alluvium and slope deposits. the lower-jurassic calcare massiccio formation, an over 500 m thick unit in which the furlo gorge is entrenched (cf. figs. 3, 4), consists of massive dolomitic limestones of carbonate platform environment and is the oldest outcropping unit. it is overlain by a c.ca 600700 m thick sedimentary “multilayer” extending from the lower jurassic up to the lower miocene, consisting of calcareous/marly-calcareous units alternating with marly/marly-calcaraeous ones. the jurassic units, ranging from the calcare massiccio up to the base of the maiolica formation, show rather complex facies associations and significant lateral lithostratigrafic differentiation (cf. cecca et al., 1999 and references therein), hinting at local depositional environments matching up with a fault-block seamount slope. on the contrary, the cretaceous-miocene units (from the midupper part of the maiolica up to the scaglia cinerea and bisciaro formations), display a significant lateral continuity and rather homogeneous lithofacies representative of an overall pelagic depositional environment. local occurrence of slumps and calciturbidites is fig. 3 geomorphologic sketch of the monti del furlo sector enclosing the furlo gorge and location of the areas described in the text. schema geomorfologico del settore dei monti del furlo comprendente la gola del furlo e ubicazioni delle aree descritte nel testo. 206 also noticeable (cf. alvarez & lowrie, 1984; stow et al., 1986) as a clue to topographic irregularities in the palaeo-basin floor. because of its geographical collocation as well as of the occurrence of both many good outcrops and significant facies differentiation in quite a small zone, the monti del furlo area is to be regarded as an important geologic site. many of its outcrops allow for detailed visualization and reconstruction of crucial stages of the marche apennines meso-cenozoic geologic history, from the drowning of the lower-jurassic shallow-water carbonate platform to the establishment of persisting pelagic conditions (cf. various authors, 1991; cecca et al., 1999). moreover, several fossiliferous sites as well as regional-markers outcrops (e.g. the bonarelli level or the k/t level) arouse both the scientific community and keen naturalists’ interest in the geologic heritage of this area. 3. the geomorphosites the monti del furlo area, corresponding to the northernmost sector of the marche ridge (fig. 1) anticline relief, displays such a clear morphostructural imprint (figs. 2, 5) that it can be included (togheter with petrano mt., see nesci et al., 2005) among the best examples of carbonatic anticline ridges in the central apennines. in addition, the geomorphologic interest of the area is greatly increased by an impressive transverse canyon, namely the furlo gorge. the main sectors of the ridge (i.e . monte pietralata and monte paganuccio, fig. 2) perfectly display both the rounded geometry of the anticline and its north-west and south-east plunge-out areas. on the anticline flanks well developed homoclinal ridges and flatirons are found (figs. 2, 6). the morphostructure has developed its peculiar arrangement by different geomorphic processes, from weathering and mass movements to slope-wash and cryonivation. whatever the occurring process, selective weathering and erosion have often been able to highlight both lithologic contrasts of the jurassic-miocene “multilayer” and structural features, such as fault-zones and bended bedding surfaces. since weathering and erosion have been more effective under pleistocene cold climatic conditions, several structural landforms characterising the modern landscape of the area must be regarded as almost entirely derived from past morphogenetic stages. some peculiar landforms (i.e. broad natural amphitheatres and ricter slopes), in particular, are relics of past cold climatic conditions. others, such as those related to mass-wasting or weathering, are still more or less active, even though they can have experimented stages of more intense activity in the past. the whole area is crossed by several paths and roads, some of which can be of peculiar geomorphologic interest, since they cross both the furlo gorge and the nearby geomorphosites. as a matter of fact, they allow people to approach many significant landforms and to have panoramic views on both the monti del furlo area and on the metauro-candigliano valley and terraces. two of them match with as many geologic itineraries described by coccioni et al. (1994) and savelli & tramontana (2001): since they also cross areas of major geomorphologic interest, they are suitable for educational as well as scientific purposes and worth improving as geomorphologic paths too. a. diligenti et al. fig. 4 panoramic view of the south-western side of the monti del furlo anticline ridge showing the outcropping jurassic formations. please note the entrance of the furlo gorge and, on the foreground, the flat top-surface of the holocene terrace alluvium. veduta panoramica del fianco sud-occidentale della dorsale anticlinalica dei monti del furlo con indicate le formazioni giurassiche affioranti. si notino l’ingresso della gola del furlo e, in primo piano, la superficie pianeggiante delle alluvioni terrazzate oloceniche. 207 3.1 the furlo gorge geomorphosite the principal geomorphologic peculiarity of the area is, without any doubt, the furlo gorge, a deep canyon cross-cutting the anticline ridge (figs. 2-5 and 7-8). as a matter of fact, indications which are important for both scientific and educational standpoint definitely arise from such an attractive and scenic gorge (cf. bartolini & peccerillo, 2002). its sub-vertical walls (fig. 8), hanging over 500 m high on the present river, have been cut into the dolomitic limestones of the calcare massiccio formation by the candigliano river, the major right tributary of the metauro river. the evolution of the drainage net of the metaurocandigliano river basin started, perhaps, as long ago as in lower messinian time, but only during the upper pliocene-quaternary did the net achieve the essentials of its modern organization (cf. mayer et al., 2003). it was just at that time that the anticline ridge bypass was performed according to still largely uncertain mechanisms, which are object of a long-lasting debate and of different interpretations (e.g. mazzanti & trevisan, 1978, alvarez, 1999 and references therein). the furlo gorge devegeomorphosites in the landscape ... fig. 7 the upstream sector of the furlo gorge. veduta del tratto iniziale della gola del furlo. fig. 6 flatirons on the resistant limestones of the lower miocene bisciaro formation. north-eastern flank of pietralata mt., monti del furlo anticline ridge. flatirons modellati sui calcari della formazione del bisciaro (miocene inf.). fianco nord-orientale di m. pietralata, dorsale anticlinalica dei monti del furlo. fig. 5 panoramic view emphasizing the morphostructural arrangement of the monti del furlo anticline ridge. veduta panoramica che evidenzia l’assetto morfostrutturale della dorsale anticlinalica dei monti del furlo. fig. 8 vertical cliffs in the downstream reach of the furlo gorge. le pareti verticali del tratto iniziale della gola del furlo. 208 lops along a dominant sw-ne joint direction (mayer et al., 2003) just corresponding with a pronounced axial culmination of the anticline, as shown both by geologic data and the morphostructural arrangement itself (cf. fig. 2). moreover, a second narrow canyon (i.e. the socalled “il buzzo”) parallel to the main one cuts the external flank of the anticline ridge less than 1 km to the south-east of the furlo gorge (figs. 2, 3, 5). the unusual structural position as well as the occurrence of a second minor canyon, have recently led mayer et al. (2003) to interpret the furlo gorge as the result of capture mechanisms, rather than superposition followed by antecedence as previous authors asserted. in the geomorphosite area, the youngest (i.e. second half of the middle pleistocene-holocene) evolution stages of the valley reach enclosing the gorge, are underlined by fluvial terraces occurring on both flanks of the anticline ridge just outside the gorge (cf. fig. 3, 4, 9). in fact, several well preserved terraces and some terrace-alluvium outcrops occur close to it, reaching elevations as high as 155 m above the modern stream (nesci et al., 1990, p. 69), and highlighting the presence of four main cycles of aggradation related to as many pleistocene cold stages (cf. nesci et al., 1995 and references therein). in actual fact, both the presence of terraces and their altitudinal distribution underline a vertical uplift of the structure, but no evidence of terrace deformation relating to active thrusting and folding of the anticline can be alleged (cf. di bucci et al., 2003). besides these major subjects of scientific, educational and scenic value, both in the furlo gorge and in its vicinity the geomorphosite includes many other minor -yet noticeablelandforms and landform assemblages, which contribute to enhance the geomorphologic significance of the site. some of them are worth mentioning, as follows. small hanging valleys ending against the edge of the furlo gorge cliffs, although dried up for most part of the year, are able to produce impressive waterfalls when heavy storms and/or rapid snow-melt occur (fig. 10). narrow potholes can also be observed at the foot of the ephemeral waterfalls. such suggestive landforms due their origin to a huge difference in down-cutting rates of the candigliano river and of its small ephemeral tributaries flowing on the hard dolomitic limestones at the core of the anticline ridge. small caves (e.g. grotta del grano, i.e. “corn cave”, cf. fig. 11), tens of meters large but only a few metres deep, owing their origin to moderate karst processes associated with cryoand thermo-clastic processes, characterise the feet of the cliffs. in addition, the calcare massiccio walls of the furlo gorge bear well-developed weathering landforms both on relatively weak rock-beds and along faults. in detail, a series of weathering niches developed both along strata and along joint systems (fig. 11). in the first case, apart from a very crude bedding of the dolomitic limestones forming the gorge walls, the occurrence of weaker beds is locally underlined by a series of weathering niches arranged along curved lines which follow the bending of the anticline structure cross-cut by the gorge. in the latter case, because of poor re-cementation by carbonates, the rock has been made less resistant to weathering all a. diligenti et al. fig. 9 upper pleistocene (up) and late-middle pleistocene (mp) fluvial terraces close to the downstream termination of the furlo gorge. terrazzi del pleistocene superiore (up) e del pleistocene medio-finale (mp) in prossimità dello sbocco della gola del furlo. fig. 10 waterfalls during a stage of activity of hanging valleys inside the furlo gorge. cascata in un periodo di attività di una delle valli sospese presenti all’interno della gola del furlo. along the fractured zones, thus improving the production of niches by cryoand thermo-clastic processes associated with more or less pronounced carbonate solution. on the contrary, narrow rocky walls and ridges as well as sets of rock-spurs (figs. 12, 13) align with those major faults along which resistant fault-rocks formed because of strong calcium-carbonate cementation. outside the gorge area such fault-related landforms are lacking because of softer terrains occurrence. they are generally replaced by slopes of faultline scarps or by fault scarps exhumed by selective erosion (cf. fig. 7.2 in savelli & tramontana, 2001). anthropic modifications performed in more or less recent historical time are also noticeable, although flawlessly harmonized with the natural landscape. specifically, two roman tunnels (2nd century bc-1st century ad, cf. luni, 1993) chiselled out of rock walls of the furlo gorge characterise the canyon entrance. furthermore, a dam built up at the beginning of the 20th century has produced an attractive, narrow and deep artificial lake inside the gorge itself. 3.2 geomorphosites in the furlo gorge vicinity since the furlo gorge is not the one and only significant geomorphologic element of the area under discussion, two sites close to the gorge and valuable as geomorphosites in their own right, are worth mentioning. one of them (i.e. il buzzo) is related to the furlo gorge geomorphosite, thus contributing to highlight its scientific as well as educational significance. the other one (ca’ i fabbri) is to be considered in order to better understand how important mass movements are in shaping the anticline ridge where the gorge developed. 3.2.1 il buzzo the so called “il buzzo”, whose geomorphologic importance has just been mentioned, is a very narrow gorge running parallel to the furlo one (figs. 2, 3, 5). it consists in a close “v” shaped valley whose bottom is over-deepened by a gorge which in some places is less than two metres wide. the valley, whose head is covered by upper pleistocene stratified slope-waste deposits, is excavated in well-bedded jurassic limestones, whereas its bottom is incised in the massive limestones 209geomorphosites in the landscape ... fig. 12 fault-related rock-spur produced by weathering in the intermediate left side of the furlo gorge. sperone roccioso prodotto dalla degradazione lungo una zona di faglia, versante di sinistra della gola del furlo. fig. 11 small caves and weathering niches aligned along both bedding and fracture-systems close to the grotta del grano, intermediate sector of the furlo gorge. nicchie di degradazione lungo sistemi di fratture e superfici di stratificazione in prossimità della grotta del grano, settore intermedio della gola del furlo. fig. 13 segmented fault-related rock-wall produced by weathering on the intermediate right side of the furlo gorge. please note on the foreground the artificial lake due to damming of the gorge exit. muro di faglia parzialmente smantellato dovuto a degradazione selettiva, fianco destro della gola del furlo. si noti in primo piano l’invaso artificiale prodotto dalla costruzione di una diga all’uscita della gola. belonging (according to cecca et al., 1999) to the lower-jurassic corniola massiccia formation (cf. fig. 4). “il buzzo” valley cuts the anticline ridge extending upstream far enough beyond the axis of the structure, so that the initial valley reach falls in the internal anticline flank (cf. fig. 2). therefore, the valley head is furrowed in the south-western side of the anticline ridge, yet it does not bypass the mountain massif like the nearby furlo gorge does. the gorge is run by a minor stream, presently dry most of the year. its vertical and overhanging walls display a strong passive structural control by joint systems trending in a sw-ne direction. a particular rock bridge (fig. 14) occurs in the intermediate valley reach, where slid rock-blocks only partly reworked by stream obstruct the valley bottom to a degree. 3.2.2 ca i fabbri landslide the monti del furlo mountain ridge is a remarkable natural example of an exhumed anticline, where the geologic structure is distinctly replicated by the relief topography (cf. figs. 2, 5). although the ridge has been shaped by different processes, the role of mass movements, as in the past, is today one of the most effective (cf. fig. 3). indeed, the flanks of the anticline ridge have been extensively denudated by more or less shallow landsliding, able to highlight both lithologic contrasts and structural features, such as bended bed-surfaces. these processes are generally favoured by the occurence of weak marly/clayey-marly interbeds/units as well as by a downslope-dipping of layers prevailing on both the anticline ridge sides. additional control by intense jointing of rock units can often intervene, emphasizing the local tendency to landsliding. the ca i fabbri landslide is the best example of several large landslides which are well recognisable all over the anticline flanks (fig. 3); by the way, it is very close to the furlo and il buzzo gorges and allows for some significant panoramic views. the landslide originates on the upland flats corresponding with the anticline crest. it is a rock-slump extending c.ca 2 km downslope all over the north-eastern anticline flank. a fresh, marked arcuate cliff rimmed by tension cracks marks off the landslide head. in the upper part of the slid body, a multitude of characteristic rock-pillars alternating with trenches and counterslopes -although covered by a beech forestis so evident and distinctive to capture the attention of students as well as of common people walking along the wood paths. the slid mass becomes more and more disrupted and chaotic downslope, where its thickness (over 100 m) is appreciable because of deep gully dissection of the landslide body. moreover, the landforms freshness indicate a very recent mobilization of the upper sector of the landslide, whereas the occurrence of both deep dissection and smoothing of the sliding-related forms hints to an inactivity at the toe. acknowledgements this paper was funded by miur to o. nesci (cofinanced project “the geosites of the italian landscape: research, evaluation and enhancement”, 2001). special thanks to nicole savelli for revising the english text. references alvarez w. (1999) drainage on evolving fold-thrust belts: a study of transverse canyons in the apennines basin research, 11, 267-284. alvarez w. & lowrie w. (1984) magnetic stratigraphy applied to synsedimentary slumps, turbidites and basin analysis: the scaglia limestones at furlo, italy geol soc. am. bull., 95, pp. 324-336. bartolini c. & peccerillo a. (2002) i fattori geologici delle forme del rilievo pitagora, bologna, 216 pp. bisci c. & dramis f. (1991) la geomorfologia delle marche in: a. minetti, t. nanni, f. perilli, l. polonara & m. principi (eds.), l’ambiente fisico delle marche. geologia, geomorfologia, idrogeologia, regione marche, giunta regionale, assessorato urbanistica-ambiente, pp. 81-113. cecca f., conte g., cresta s., d'andrea m., graziano r., molinari v., pantaloni m., pichezzi r. m., rossi m., catenacci v., cacopardo m., censi neri p., pannuti v., borgia m. g., erba, menichetti m. & raffi i. (1999) risultati preliminari del rilevamento nel settore sud-occidentale del foglio n. 280 fossombrone della carta geologica d'italia a scala 210 fig. 14 the curious rock-bridge inside the “il buzzo” gorge. il singolare ponte naturale all’interno della gola de “il buzzo”. a. diligenti et al. 1:50.000 -boll. serv. geol. it., 115. coccioni r., moretti e., nesci o., savelli d., tramontana m., veneri f. & wezel f.c., with the contribution of cecca f., cresta s. & passeri l. (1994) da sansepolcro a fossombrone (km 122). assetto stratigrafico e strutturale della successione umbro-marchigiano-romagnola in: l. passeri (ed.), appennino umbro-marchigiano, 15 itinerari, guide geologiche regionali, vol 7, be-ma, milano, pp. 103-118. deiana g. & pialli g. (1994) the structural provinces of the umbro-marchean apennines mem. soc. geol. it., 48, pp. 473-484. di bucci d., mazzoli s., nesci o., savelli d., tramontana m., de donatis m. & borraccini f. (2003) active deformation in the frontal part of the northern apennines: insights from lower metauro river basin area (northern marche, italy) and adjacent adriatic off-shore journ. geodynamics, 36, pp. 213-238. luni m. (1993) la flaminia nelle gole del furlo e del burano arti grafiche editoriali srl, urbino, 67 pp. mayer l., menichetti m., nesci o. & savelli d. (2003) morphotectonic approach to the drainage analysis in the north marche region, central italy quat. intern., 101-102, pp. 157-167. mazzanti r. & trevisan l. (1978) evoluzione della rete idrografica nell’appennino centro-settentrionale geogr. fis. dinam. quat., 1, pp. 55-62. nesci o., savelli d. & mengarelli d. (1990) i terrazzi vallivi del 1° ordine nei bacini dei fiumi metauro e foglia (appennino marchigiano) geogr. fis. dinam. quat., 13, pp. 63-73. nesci o., savelli d., calderoni g., elmi c. & veneri f. (1995) le antiche piane di fondovalle nell’appennino nord-marchigiano in: g. b. castiglioni & p. r. federici (eds.), assetto fisico e problemi delle pianure italiane, mem. soc. geogr. it., 53, pp. 293-312. nesci o., savelli d., diligenti a. & marinangeli d. (2005) geomorphological sites in the northern marche (italy). examples from autochthon anticline ridges and from val marecchia allochthon il quaternario, this volume. p anizza m. (2001) geomorphosites: concepts, methods and examples of geomorphological survey chinese sci. bull., 46, pp. 4-6. panizza m. & piacente s. (2003) geomorfologia culturale pitagora, bologna, 350 pp. savelli d. & tramontana m. (2001) itinerario 7. il versante sinistro della gola del furlo in: g. ciarapica & l. passeri (eds.), guide geologiche regionali, appennino umbro-marchigiano, bema (ed.), 7 (2), pp. 59-66. stow d.a.v., wezel f.c., savelli d., rainey s.c.r. & angell g. (1986) depositional model for calcilutites: scaglia rossa limestones, umbro-marchean apennines in: d.a.v. stow & d.j.w. piper (eds.), fine-grained sediments: deep-water processes and facies, blackwell publ. comp., oxford, pp. 223-243. various authors (1991) le emergenze geologiche e geomorfologiche delle marche. piano paesistico ambientale regionale industrie grafiche f.lli aniballi, ancona, 711 pp. wimbledon w.a.p. (1999) l’identificazione e la selezione dei siti geologici, una priorità per la geoconservazione in: g. poli (ed.), geositi, testimoni del tempo, edizioni pendragon, pp. 52-63. 211geomorphosites in the landscape ... microsoft word 00_indice_bm03 available online http:/amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 25 (1), 2012, 35-40 u/th dating of a cladocora caespitosa from capo san marco marine quaternary deposits (sardinia, italy) maurizio d’orefice1, roberto graciotti1, sergio lo mastro2, cristina muraro1, marco pantaloni1, michele soligo2 & paola tuccimei2 1 ispra, servizio geologico d’italia, rome, italy 2 dipartimento di scienze geologiche, università roma tre, rome, italy corresponding author: r. graciotti <roberto.graciotti@isprambiente.it> abstract: a whole specimen, not reworked and well preserved of cladocora caespitosa has been found within the marine quaternary deposits, outcropping along the eastern coast of the capo san marco promontory. the u/th dating of this sample has provided a minimum age of 70 ± 4 ka b.p. this dating allows to state that these marine deposits, containing the coral, are not holocene in age. keywords: marine quaternary deposits, cladocora caespitosa, u/th dating, tyrrhenian, sardinia. 1. introduction the geological survey of italy, concerning the institutional activities related to the realization of the geological map of italy at 1: 50.000 scale (carg project), has done quick geological surveys to check and monitoring some sample areas of the 528 oristano geological sheet (middle-western sardinia), still in progress. in particular, marine and continental quaternary deposits were taken into account. in the middle-western sardinia, sinis peninsula and eastern coast of the capo san marco promontory, these deposits occurred in peculiar outcroppings which have been studied in detail by several authors (maxia & pecorini, 1968; ulzega et al., 1982; carboni & lecca, 1985; davaud et al., 1991; kindler et al., 1997; melis et al., 2001; lecca & carboni, 2007; andreucci et al., 2009; coltorti et al., 2010; thiel et al., 2010). the research has especially addressed marine quaternary deposits, in relation with a scientific debate which has recently risen about the chronological attribution of these deposits (aiqua, 2007; bartolini et al., 2008; catto, 2010). in the 528 oristano geological sheet “the beach and beach ridge deposits” have been chronologically attributed to holocene age, instead of the upper pleistocene age (tyrrhenian) reported in literature and in the official geological map of italy (regione autonoma della sardegna, 1989). during the field activity many fossils have been collected including a specimen of cladocora caespitosa which has been dated with the u-series method. the aim of this note is to give a additional element to dating the quaternary deposits outcropping in this area of the sardinia region, and to provide a useful contribution to the scientific debate in progress. 2. geological setting the capo san marco promontory, which from a fig. 1 location map of the sinis peninsula (melis et al., 2001; modified). d’orefice m. et al. 36 geomophological point of view extends a few kilometers offshore, represents the end of the sinis peninsula (fig. 1). the western coast consists of an high and steep miocene-pliocene cliff, while the eastern coast, gently dipping seaward, is mainly made of marine and continental quaternary deposits. in this area, in fact, the pre-quaternary bedrock crops out only in a few sites along of the coast where the quaternary deposits were dismantled by the intense wave action. the basal portion of the substrate is represented by the capo san marco formation (cherchi et al., 1978), divided into two facies: the lower one consists of “dark grey clays” and the upper one is made of “marly calcareous deposits”. the outcropping thickness is about 50 m, the age is upper tortonian – lower messinian. the nuraghe baboe formation (spano, 1989) overlies the marly calcareous deposits of the capo san marco formation, with a transgressive unconformity surface. this unit consists of a marine succession made of breccias, conglomerates, sandstones, calcareous sandstones, silty-marly clays, calcarenites and marly fig. 2 satellite view (from google earth) with location of outcrops and sampling point of the cladocora caespitosa. table 1 uranium content, uranium and thorium activity ratios and age of the coral. u/th dating of a cladocora caespitosa from capo san marco … 37 mudstone. the thickness is about 35 m, the age is lower pliocene. the golfo di oristano basalt formation (costa randata facies), unconformably overlying on the previous formations, represents the top and the southern cliff of the promontory. these basalts, dated 3.12 ma (beccaluva et al., 1985), are made of several superimposed flows and their maximum thickness is about 30 m; the occurrence of columnar structures suggests a slow cooling of the lavas. 3. observations on quaternary deposits the quaternary deposits widely crop out in the area of the 528 oristano geological sheet. the best and more complete stratigraphic sections occur near the san giovanni di sinis area, within which some authors recognize different facies (maxia & pecorini, 1968; ulzega et al., 1982; carboni & lecca, 1985; davaud et al., 1991; kindler et al., 1997; melis et al., 2001; lecca & carboni, 2007; andreucci et al., 2009; coltorti et al., 2010; thiel et al., 2010). quaternary deposits have been also recognized along the fossil beach ridge that closes the cabras lagoon. these deposits are formed by thyrrenian bioclastic calcarenites (forti & orrù, 1995). the quaternary deposits crop out without interruption all over the eastern coast of the capo san marco promontory, from the southernmost end up to 1 km to the north of tharros archeological site. these deposits are often fractured, disrupted and prone to fall and topple landslides due to the intense marine erosive processes acting along the coasts of the promontory. at the tip of the promontory the basalts are overlapped by aeolian deposits, made of well cemented fig. 3 la caletta site. geometrical relationships between aeolian and marine deposits. a) front view of the outcrop and presentday tidal notch in the aeolian deposits. b) detail of the marine deposit. c) lateral view of the outcrop. d) detail of the marine deposit clearly capped by aeolian deposit. d’orefice m. et al. 38 fig. 5 the specimen of cladocora caespitosa which has been dated using u/th method. quartz-sandstone, characterized by high angle cross stratification with foresets landward dipping. the aeolian deposits continue below sea level and are characterized by a recently formed tidal notch. these deposits are modelled by a flat marine erosional surface, gently sloping seaward, located at about 4 m above sea level, delimited upslope by a notch of about 50 cm of height. this surface is capped by 1 m-thick marine deposit. the lower portion consists on huge prevailing basalt blocks, well rounded, with a diameter up to 50 cm, in a well cemented, gravelly-sandy matrix, with abundant fossils. the upper part consists of a well cemented level of coarse to medium fossiliferous sandstone. the fossils are mostly bivalves (anomia ephipphium, arca noe, fissurella italica, glycimeris sp., cardium sp., ostreids) and gastropods (murex taurinensis, trochocochlea turbinata, purpura haemastoma, patella ferruginea). the age of the aeolian deposits, assigned using osl dating on a sample collected just above the notch, is 174 ± 13 ka, thus referable to the middle pleistocene (thiel et al., 2010). at la caletta site (fig. 2) a marine deposit crops out at present-day sea level. this deposit is composed by huge meter-sized, well rounded basaltic boulders, in a gravelly-sandy supporting matrix, rich in fossils (ostrea sp., arca noe, glycimeris sp., patella ferruginea, etc.). this sedimentary body, dipping 10° seaward, rise upward for a few meters along the slope. it is completely capped by upper pleistocene aeolian quartz-sandstones which deep below sea level. in this site the geometrical relationships between these deposits can be observed in a three-dimensional view. in fact, it is possible to observe the marine deposits underlying the aeolian sandstones through several joints expanded by marine erosion (fig. 3). northward, in the direction of tharros (figs.1-2), a peculiar beach deposit has been found. this 50 cm-thick layer is made of medium to coarse-grained, well cemented sandstone, rich in mytilus galloprovincialis and other bivalves (fig. 4). this marine deposit is very similar to that described by lecca et al. (2007) and by andreucci et al. (2009) in the sinis peninsula, about 1 km away. in this site a planar bedded sandstone overlying the mytilus galloprovincialis layer has been dated using osl method, providing an age of 120 ± 10 ka (andreucci et al., 2009). during the field survey it was noteworthy the finding of one whole specimen of cladocora caespitosa at about 2.5 m above sea level. this fossil has been collected from marine quaternary deposits unconformably lying on the bedrock with an articulated erosional surface. the specimen not reworked and well preserved has been considered suitable for an isotopic dating according to the u/th method. 4. u/th dating corals are considered excellent samples to be dated with u-series disequilibria methods because in most cases they consist of pure calcium carbonate, free from a detrital component that makes problematic the dating of dirty carbonates. the 230th/234u method is the most widely used dating technique applied to corals and is based on the extreme fractionation of the parent isotopes 238u and 234u from their long-lived daughter 230th in the hydrosphere. uranium, markedly more soluble than th in the surface and near-surface environments, is readily mobilised as the highly soluble uranyl ion (uo2 2+) and its complexes, whereas th is easily hydrolyzed and precipitated or adsorbed on detrital particles. uranium is co-precipitated with caco3 on exsolution of co2, fig. 4 view of the mytilus galloprovincialis layer. u/th dating of a cladocora caespitosa from capo san marco … 39 fig. 6 diffractogram showing the aragonitic (ar) nature of the coral with moderate calcite amount (cc) and detrital fraction: quartz , halite gypsum. while th is generally negligible. in the absence of detrital th, 230th only forms in situ by radioactive decay of co-precipitated u. in a closed system the extent to which the 230th/234u activity ratio has returned towards unity is a function of time, taking into account also the state of disequilibrium between 234u and 238u (kaufman & broecker, 1965). moreover, it is important to verify the original aragonitic nature of the coral and check the eventual presence of calcite. the occurrence of relevant calcite indicate that weathering processes have affected the coral after its burial, with consequent opening of the chemical system. in this case, semi-quantitative x-ray diffractometry analysis has evidenced the aragonitic nature of the coral with the presence of moderate calcite amount (fig. 6) that can be estimated around approximately 10%. about 3 g of coral were ultrasonically washed in deionized water and dissolved in nitric acid. few milliliters of hydrogen peroxide were added and heated at 100 °c in order to destroy organic matter. isotopic complexes of uranium and thorium were extracted according to the procedure described in edwards et al. (1986) and alpha-counted using high resolution ion implanted ortec silicon surface barrier detectors. the age, 70 ± 4 ka, was calculated by means of isoplot/ex (version 3·0), a plotting and regression program designed by ludwig (2003) for radiogenic-isotope data. u-series data are reported in table i. errors are quoted as 1σ. 230th/232th activity ratio, higher than 50, indicates that the coral does not contain a significant detrital fraction. furthermore, the uranium content, about 3 ppm, approaches the average value of uranium abundance in corals and the initial 234u/238u activity ratio (234u/238ui) of the carbonate correspond to that of the marine water. these three data are an evidence of the good quality of the obtained age. 5. conclusions the u/th dating on a sample of cladocora caespitosa has provided an age of 70 ± 4 ka b.p. the specimen of cladocora caespitosa, not reworked and well preserved, was sampled at about 2.5 m above sea level within the marine quaternary deposits, overlying the miocene-pliocene bedrock, along the eastern coast of the capo san marco promontory. the diffractometric analysis showed the sample is mainly composed by aragonite. for the u/th dating must be taken into account the occurrence of the calcite which could cause the rejuvenation of the samples. in this case study, considering the modest quantities of calcite, the age of 70 ± 4 ka b.p. represents the minimum age of the sample. based on these considerations and with reference to the isotopic curve related to the last 300 ka (martinson et al., 1987) the examined sample can be located at the end of the isotopic stage 5 even assuming the rejuvenation of the sample for the presence of moderate calcite amount (fig. 6). this finding agrees with the results reported in dorale et al. (2010) and tuccimei et al. (2010), inferred from phreatic overgrowths on speleothems in coastal caves of mallorca (balearic islands spain). these authors assert that the western mediterranean relative sea level stood at about 1m above present sea level during marine isotope stage (mis) 5a, between ~ 82 and 80 ka ago. furthermore, the data of mallorca coastal caves, show good coherence with those observed from tuccimei et al. (2012) in the capo caccia area (north-western sardinia), located not far from capo s. marco. the u/th dating of cladocora caespitosa allows to state that the marine deposits outcropping along the eastern coast of the capo san marco promontory are not holocene in age, as reported in the documents and maps up to now realized for the 528 oristano geological sheet, still in progress. references aiqua (2007) notizie d’interesse. il quaternario, 20 (1), 85. andreucci s., pascucci v., murray a.s., clemmensen l.b (2009) late pleistocene coastal evolution of san giovanni di sinis, west sardinia (western mediterranean). sedimentary geology, 216, 104116. bartolini c., bonfiglio l., carrara c.,carraro f., ciaranfi n., girotti o., vai g. (2008) commenti e repliche. il quaternario, 21 (1b), 375-376. beccaluva l., civetta l., macciotta g.p., ricci c.a. (1985) geochronology in sardinia: results and problems. rend. soc. it. min. petr., 40, 57-72. carboni s., lecca l. 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(1991) enregistrement des variations eustatiques dans des dépôts littoraux du pleistocéne supérieur san giovanni di sinis (sardaigne occidentale). bull. soc. géol. fr., 162, 523-533. dorale j.a., onac b.p., fornós j.j., ginés j., ginés a., tuccimei p., peate d.w. (2010) sea-level highstand 81,000 years ago in mallorca. science, 327, 860-863. edwards r.l. (1988) high precision thorium-230 ages of corals and the timing of sea level fluctuation in the late quaternary. ph.d. thesis, california institute of technology, pasadena california, usa. edwards r.l.,chen, j.h., wasseburg g.j. (1986) 238u234u230th-232th systematics and the precise measurement of time over the past 500 000 years. earth planet. sci. lett. 81, 175-192. forti s., orrù p. (1995) geomorfologia costiera e sottomarina della penisola del sinis (sardegna occidentale). boll. soc. geol. it., 114, 3-21. kaufman a, broecker w.s. (1965) comparison of 230th and 14c ages of carbonate materials from lakes lahantan and bonneville. journal of geophysical research 70, 4039-4054. kindler p., davaud e., strasser a. (1997) tyrrhenian coastal deposits from sardinia (italy): a petrographic record of high sea levels and shifting climate belts during the last interglacial (isotopic stage 5e). pal. pal. pal., 133, 1-25. lecca l., carboni s. (2007) the tyrrhenian section of san giovanni di sinis (sardaigne): stratigraphic record of an irregular single high stand. riv. it. paleont. strat., 113(3): 509-523. ludwig k.r. (2003). using isoplot/ex, version 3. a geochronological toolkit for microsoft excel. berkeley geochronology ctr. spec., pub. 4. maxia c, pecorini g. (1968) il quaternario della sardegna. atti x° congresso internazionale di studi sardi, 247-266. melis r.t., palombo m.r., mussi m. (2001) mammuthus lamarmorae (major, 1883) remains in the pretyrrhenian deposits of s. giovanni di sinis (western sardinaia, italy). in: g. cavaretta, p. gioia, m. mussi & m.r. palombo (eds.). “the world of elephants”, pubbl. cnr, roma, 2001, 481-485. martinson d.g., pisias n.g., hays, j.d., imbrie, j.d., moore t.c., shackleton n.j. (1987) age dating and the orbital theory of the ice ages: development of a high-resolution 0 to 300,000-year chronostratigraphy. quaternary research, 27, 1-29. regione autonoma della sardegna (1989) carta geologica d’italia alla scala 1:100.000: fogli 216-217 “capo s. marco – oristano”. spano c. (1989) macrofauna circalitorale del pliocene inferiore di capo s. marco (sardegna occidentale). riv. it. paleont. strat., 95(2), 137-172. thiel c., coltorti m., tsukamoto s., frechen m. (2010) geochronology for some key sites along the coast of sardinia (italy). quaternary international, 222, 36-47. tuccimei p., onac b.p., dorale j.a., fornós j.j., ginés j., ginés à., spada g., ruggieri g., mucedda m. (2012) decoding last interglacial sea-level variations in the western mediterranean using speleothem encrustations from coastal caves in mallorca and sardinia: a field data model comparison. quaternary international. doi: 10.1016/j. quaint 2011.10.032, article in press tuccimei, p., soligo, m., ginés, j., ginés, a., fornós, j., kramers, j., villa, i.g. (2010) constraining holocene sea levels using u-th ages of phreatic overgrowths on speleothems from coastal caves in mallorca (western mediterranean). earth surface processes and landforms 35 (7), 782-790. ulzega a., ozer a., lecca l., leone f., pecorini g. spano c., cordy m.j. (1982) comptes-rendus de l’excursion-tablr ronde sur le tyrrhenien de sardaigne. cagliari 21-28 avril 1980/ inqua (livretguide), 88 pp. ms. received: february 3, 2012 final text received: march 5, 2012 imp.iandelli_piccini rapporti tra morfogenesi carsica ed evoluzione paleogeografica nelle aree costiere della toscana meridionale niccolò iandelli 1, leonardo piccini 1 1 dipartimento di scienze della terra, università degli studi di firenze; e-mail: leonardo-piccini@.unifi.it. riassunto: n. iandelli & l. piccini, rapporti tra morfogenesi carsica ed evoluzione paleogeografica nelle aree costiere della toscana meridionale. (it issn 0394-3356, 2007). nella toscana meridionale si trovano estesi affioramenti di brecce carbonatiche che presentano superfici a bassa pendenza con estesi fenomeni carsici. un’analisi morfologica ha permesso di riconoscere due tipi di superfici: spianate sommitali e terrazzi marini d’erosione. le prime sono presenti soprattutto nell’area del poggio del leccio, la cui natura permette di escludere per esse un controllo lito-strutturale. queste superfici si trovano prevalentemente intorno a 250 m di quota e in misura minore intorno a 300 m s.l.m.. i terrazzi marini si trovano invece a quote comprese tra 0 e 70 m. le forme carsiche comprendono numerose grotte le quali possono essere distinte in due tipi principali: cavità relitte, di forma grossomodo a camera, presenti soprattutto nelle zone sommitali a bassa pendenza; cavità ramificate a sviluppo orizzontale, appartenenti a due generazioni, di cui la più antica è situata intorno a 250 m di quota. sulla base delle caratteristiche del rilievo e delle cavità carsiche è stato possibile ipotizzare le principali fasi evolutive dei fenomeni carsici in relazione all’evoluzione morfotettonica di quest’area costiera. in occasione della trasgressione pliocenica, si forma probabilmente una vasta piattaforma d’erosione marina in rocce calcaree, che è poi smembrata e sollevata in modo differenziale durante il pliocene superiore e il quaternario. durante la progressiva emersione, si sviluppano forme carsiche legate alla presenza di una tavola d’acqua in prossimità della superficie della piattaforma, nonché cavità costiere ai suoi margini. il sollevamento porta porzioni di questa superficie sino a 250-300 m di quota, conservati nelle spianate sommitali a bassa pendenza del poggio del leccio. nel pleistocene medio-superiore si ha l’esumazione di cavità relitte epifreatiche più antiche e la formazione di una nuova generazione di cavità costiere in corrispondenza della zona di oscillazione eustatica del livello del mare. abstract: n. iandelli & l. piccini, relationships between karst morphogenesis and palaeogeographic evolution in coastal areas of southern tuscany. (it issn 0394-3356, 2007). in southern tuscany, close to the border with lazio region, wide outcrops of carbonate breccias (calcare cavernoso) display e relief characterised by top horizontal surfaces and slope terraces with karst landforms. morphometric analysis, based on a dtm with a resolution of 10 m, has allowed us to identify some low-gradient surfaces displaced from 0 to 300 m a.s.l.. erosional surfaces are of two different kinds: old summit surfaces and marine terraces. the formers occur mainly on poggio del leccio area, as smooth-relief areas not controlled by lythologic surfaces. presently, these surfaces are located around 250 m a.s.l., up to 300 m a.s.l., whereas marine terraces are located between 0 and 70 m a.s.l.. the most peculiar feature of this area is the occurrence of surface karst and caves that can be related to palaeo-coastal environments. caves show two different patterns: chamber-shaped relict caves, occurring mainly on low gradient surfaces, and horizontal maze caves. those of first kind can be the result of the collapse of caves formed at the water table, in a coastal platform anciently located just a few tens of meters above the sea level, similar to those of many present coastal tropical karsts. horizontal maze caves can be grouped into two generations. the first one regards only few caves located around 250 m a.s.l.. the second generation is located near the present sea level and is probably due to mixing solution in epiphreatic condition. submerged caves, occurring up to 50 m below the present s.l., must be related to sea low-stands, because vadose speleothems occur inside them. the morphologic features of the area, together with the geomorphic features of caves, indicate some of the evolutionary steps that fit well with the palaeo-geographic reconstructions proposed by authors for pliocene and pleistocene. during the pliocene transgression a wide marine platform develops on carbonate rocks. the platform is fragmented and differentially raised during late pliocene and quaternary. during the emersion of this platform, caves form at the water table just near the topographic surface, whereas flank margin caves are developed along the coast. the uplift moves some portion of this old marine platform up to 250-300 m a.s.l.. during middlelate pleistocene, relict epiphreatic caves are exhumed and destroyed by surface denudation, whereas a new generation of flank margin caves is forming in the zone of eustatic variation of sea level. parole chiave: chiave: carsismo, morfologia costiera, grotte marine, toscana meridionale, orbetello. keywords: karst, coastal morphology, sea caves, southern tuscany, orbetello. il quaternario italian journal of quaternary sciences 19(1), 2006 79-87 1. introduzione gran parte delle forme carsiche superficiali (escluse ovviamente quelle a piccola scala) e soprattutto sotterranee sono forme relitte, nel senso che si sono formate in condizioni morfologiche e climatiche, talvolta legate ad un lontano passato, diverse da quelle attuali. ciò significa che gli ambienti carsici hanno un’elevata capacità di conservazione morfologica, a causa del ridotto ruolo dei processi erosivi di modellamento. quest’elevata “inerzia” morfologica rende queste aree adatte per la ricostruzione delle principali tappe dell’evoluzione paleogeografica. un caso particolare è quello dei contesti paleo-costieri, nei quali le forme carsiche possono servire come ulteriori elementi per il riconoscimento e la correlazione di antiche linee di riva, e fornire dati per la stima dei tassi di sollevamento. in italia sono presenti molte zone carsiche costiere, in corrispondenza di affioramenti carbonatici lungo le coste attuali o in prossimità di esse (cicogna et al., 2003). in toscana, gli esempi più interessanti si trovano in provincia di grosseto e riguardano estesi affioramenti di brecce carbonatiche, cartografate genericamente come calcare cavernoso, che presentano diversi 80 n. iandelli & l. piccini aspetti morfologici peculiari (piccini, 2001). i maggiori affioramenti si trovano al m. argentario e sui colli ad e di orbetello, per una superficie totale di circa 80 km2. la presenza di grandi cavità di sprofondamento, note localmente come “bottini”, aveva già attirato l’attenzione di mori (1931), che aveva anche osservato il fatto che queste si concentravano in corrispondenza di superfici con bassa energia del rilievo che caratterizzano le parti sommitali di alcuni rilievi calcarei. in anni relativamente recenti queste zone sono state oggetto di ricerche da parte di speleologi di firenze e grosseto (adiodati et al., 1998; cavanna, 1998). queste indagini hanno prodotto una ricca ed interessante documentazione e hanno portato alla scoperta di altre cavità, per un totale di 57 grotte conosciute. parallelamente sono state condotte ricerche lungo la costa, che hanno permesso la scoperta di numerose grotte subacquee sino alla profondità di circa 50 m (alvisi et al. 1987; alvisi & bruni, 1990; bard et al., 2001). queste scoperte, oltre ad avere evidenziato l’importanza di queste aree nel quadro dei fenomeni carsici della toscana, permettono oggi di affrontare una prima analisi del fenomeno con l’obiettivo di capire la genesi di queste forme carsiche e i rapporti con l’evoluzione paleogeografica di questa zona costiera. 2. inquadramento geografico e geologico l’area in oggetto si trova in provincia di grosseto, nell’estreme propaggini meridionali della toscana, al confine con il lazio. essa comprende una serie di rilievi continentali (poggio del leccio, colli di capalbio) e para-insulari (monte argentario, isola di giannutri), caratterizzati, con l’eccezione dell’argentario, da forme relativamente dolci (fig. 1). da un punto di vista geologico, questa zona è caratterizzata dalla presenza di più unità tettoniche di pertinenza ligure-piemontese (unità di cala grande, unità di santa fiora), subligure (unità di cala piatti) e toscana (falda toscana e unità toscane metamorfiche) (decandia & lazzarotto, 1980; bonazzi et al., 1992) (fig. 2). la falda toscana affiora come “serie ridotta”, in cui fenomeni di laminazione epicrostale, successivi all’accavallamento delle diverse unità, hanno portato all’elisione quasi completa della successione, lasciando spesso solo le formazioni evaporitiche basali (anidriti di burano) a interporsi tra basamento paleozoico e unità liguri (decandia et al. 1993). in gran parte dell’area, alle formazioni della falda toscana si accompagnano estesi affioramenti di brecce carbonatiche, cartografate come “calcare cavernoso”, la cui genesi è per molti versi ancora controversa. alle prime interpretazioni, che vedevano queste brecce come il risultato di una frammentazione autoclastica (per idratazione dei solfati) e/o tettonica delle formazioni basali della falda toscana, si sono aggiunte, con il tempo, ipotesi che vedono nel calcare cavernoso principalmente il prodotto di un rimaneggiamento in ambiente subaereo di rocce carbonatiche già fortemente cataclasate, in un quadro di esumazione tettonica e di elevata dinamica superficiale (carmignani & kligfield, 1990; pandeli & padoa, 1998). al di là delle ipotesi sull’origine di queste brecce, è importante sottolineare il fatto che esse, salvo situazioni particolari e localizzate, presentano un discreta omogeneità ed un’alta isotropia “in grande”, e quindi non sono in grado di dare luogo a forme a controllo litostrutturale, se non alla scala dei singoli affioramenti. 3. analisi dell’orografia in queste aree, e in particolare nella zona del poggio del leccio, poco a ne di orbetello, sono presenti superfici a bassa pendenza, sommitali e non, già segnalate da diversi autori (mori, 1931; pasquarè et al., 1983; zanchi & tozzi, 1987) e da questi interpretate come “antiche superfici d’erosione marina”. fig. 1 localizzazione geografica dell’area di studio e modello tridimensionale della zona di orbetello. la linea bianca delimita gli affioramenti di rocce carbonatiche; l’isola di giannutri è interamente costituita da rocce calcaree. location of study area and 3d model of orbetello area. the white line encircles the carbonate outcrops; giannutri island consists entirely of limestone. allo scopo di analizzare queste superfici da un punto di vista morfologico, è stato realizzato un modello digitale del terreno (dtm) basato su un’elaborazione, che prende il nome di tin (triangulated irregular network), che unisce tutte le quote note, distribuite nello spazio irregolarmente, attraverso segmenti. in questo modello, costruito utilizzando la cartografia numerica in scala 1:10.000 della regione toscana, con l’uso del software arcgis 8.3 di esri, la superficie topografica è approssimata da triangoli i cui vertici corrispondono ai punti quotati. dal tin è stato estrapolato un grid a celle quadrate con una risoluzione di 10 m. sul grid sono state compiute diverse analisi morfometriche ed elaborazioni statistiche allo scopo di mettere in risalto la presenza “anomala” di zone a bassa pendenza sulle sommità dei rilievi e lungo i versanti. le prime analisi, tese a descrivere l’ipsografia dell’area, hanno riguardato il calcolo della superficie delle fasce altimetriche, definite su diversi intervalli di quota, e la distribuzione altimetrica delle zone a bassa pendenza. la distribuzione altimetrica per fasce di quota su tutta l’area considerata (fig. 3a) mette in evidenza la presenza di estese superfici a quote comprese tra 75 e 100 m. al di sopra dei 100 m, l’andamento dell’istogramma ipsografico mostra un profilo regolare, tipico di un rilievo che potremmo definire “evoluto”, e non mette in evidenza la presenza di estese superfici sommitali a basso gradiente topografico. più significative risultano le analisi della distribuzione altimetrica delle superfici a bassa pendenza (fig. 3b). per la scelta del limite locale di “bassa pendenza” 81rapporti tra morfogenesi ... fig. 2 schema tettonico dell’area di orbetello e dell’isola di giannutri. tectonic sketch map of the orbetello region and giannutri island. fig. 3 a) istogramma ipsografico (fasce di quota di 10 m) dell’area studiata. b) distribuzione altimetrica delle superfici a bassa pendenza (< 14 %). a) hypsographic histogram (altitudinal ranges = 10 m) in the study area. b) altitudinal distribution of low-gradient surfaces (< 14%). 82 è stata prima effettuata un’analisi delle acclività, sulla base del dtm. da queste analisi sono state derivate, utilizzando diverse classi di pendenza, varie carte che hanno permesso di individuare in 8°, pari a circa una pendenza del 14 %, il valore che meglio discrimina le superfici a basso gradiente topografico presenti sui rilievi e in particolare su quelli a litologia calcarea (calcare cavernoso). questo tipo di analisi è stato effettuato sia su tutta l’area in esame, sia separatamente sui 3 gruppi orografici principali: monte argentario, poggio del leccio e colli di capalbio. i grafici ottenuti denotano la presenza di zone a bassa pendenza distribuite su diverse fasce di quota. sul m. argentario (fig. 4) si nota la presenza di zone pianeggianti soprattutto a quote di qualche decina di metri sul livello del mare. significativa è pure la presenza di zone di cresta arrotondate nelle parti alte del rilievo, di modesta estensione complessiva ma percentualmente rilevanti (le aree a quote comprese tra 550 e 580 m s.l.m. sono in gran parte a bassa pendenza). al riguardo occorre precisare che una parte, anche percentualmente significativa, delle zone di cresta che il grafico mostra come a “bassa pendenza” possono essere il prodotto dell’interpolazione tra curve di livello che il software opera nella costruzione del dtm. rilievi sul terreno e da foto aeree mostrano però l’effettiva presenza di zone di cresta arrotondate e a tratti pianeggianti. al poggio del leccio (fig. 5), oltre alle ampie superfici della piana costiera attuale, situate a quote comprese tra 10 e 20 m, si nota un modesto ma significativo picco a quote intorno a 250 m, la cui importanza è messa ben in risalto dal grafico che mostra il peso percentuale di queste superfici. anche qui il grafico che mostra la percentuale di superfici a bassa pendenza per ogni fascia di quota evidenzia la significativa presenza di zone a basso gradiente nelle aree sommitali, per le quali c’è il ragionevole dubbio che si tratti, in alcuni casi, di superfici fittizie create dal dtm. nella zona dei colli a nw di capalbio (fig. 6), le superfici a bassa pendenza sono localizzate soprattutto tra 70 e 100 m, senza contare l’attuale piana costiera, e corrispondono principalmente alle superfici di terrazzi fluviali del pleistocene e a superfici d’erosione che interessano diverse litologie del substrato, tra cui i conglomerati poligenici del miocene. le superfici a bassa pendenza individuate sono state oggetto d’indagini di campagna e con foto aeree, permettendo di distinguere, limitatamente a quelle d’erosione, due categorie: antiche superfici sommitali e piattaforme d’erosione marina. le prime sono arealmente significative soprattutto nell’area del poggio del leccio e sono impostate prevalentemente sul calcare cavernoso, la cui natura litologica, come già detto, permette di escludere per esse un controllo lito-strutturale per l’assenza di stratificazione. fig. 4 a) distribuzione altimetrica (10 m) delle superfici a bassa pendenza (< 14%) al monte argentario. b) rapporto percentuale tra superfici a bassa pendenza e superficie totale per fasce di quota (10 m). a) altitudinal distribution (10 m) of low-gradient surfaces (< 14%) in the monte argentario. b) percent ratio between lowgradient surface and total surface as function of 10 m altitudinal ranges. fig. 5 a) distribuzione altimetrica (10 m) delle superfici a bassa pendenza (< 14 %) al poggio del leccio. b) rapporto percentuale tra superfici a bassa pendenza e superficie totale per fasce di quota (10 m). a) altitudinal distribution (10 m) of low-gradient surfaces (< 14%) in the poggio del leccio area. b) percent ratio between low-gradient surface and total surface as function of 10 m altitudinal ranges. n. iandelli & l. piccini 83 più che di vere e proprie superfici pianeggianti si tratta di zone a basso gradiente topografico, con pendenze solitamente inferiori al 10 %, modellate in forme dolci e arrotondate e con idrografia poco accentuata. come risulta dai grafici, queste superfici si trovano localizzate prevalentemente intorno a 250 m di quota e, in misura minore intorno a 300 m s.l.m. queste zone risultano anche quelle maggiormente carsificate e ricche di cavità relitte. la presenza di estesi fenomeni carsici può avere avuto un ruolo importante, non solo nella conservazione, ma anche nel modellamento di queste superfici, contribuendo a conferire loro una bassa acclività “in grande” come risultato della coalescenza di depressioni carsiche dovute all’infiltrazione. i terrazzi marini sono invece localizzati a quote comprese tra 0 e 70 m. si tratta di lembi di superfici, di estensione solitamente ridotta, relativamente piane, in qualche caso associate a paleo linee di riva o a depositi costieri e sono attribuiti alle fasi trasgressive succedutesi durante il pleistocene mediosuperiore (mori, 1968; grauso e zarlenga, 1991; mazzanti, 1995). 4. il carsismo l’altro elemento peculiare di questa zona è la presenza di diffuse forme carsiche di superficie e di cavità sotterranee con morfologia molto particolare (mori, 1931, 1932; adiodati et al., 1998). forme carsiche di superficie sono presenti a tutte le scale. alla scala dell’affioramento si osservano le tipiche alveolature del calcare cavernoso, dovute a processi di alterazione e di dissoluzione differenziale dei clasti, accompagnati da fenomeni di disgregazione fisica che porta alla formazione di fori passanti, crepacci e rilievi ruiniformi. le forme più interessanti, come già accennato, sono però quelle a scala media e grande (sensu piccini, 1999) presenti soprattutto nelle zone superiori a bassa pendenza. rilievi sul terreno e con foto aeree hanno permesso di individuare un centinaio di doline, di diametro variabile da pochi metri sino a oltre 100. alcune grandi depressioni presenti nelle zone periferiche dei rilievi carbonatici e controllate anche da elementi strutturali, possono essere assimilate a polje marginali. é importante ricordare che nella zona di pianura sono presenti diversi laghi, e molti di più ve n'erano in passato (mori, 1932), che in gran parte possono essere interpretati come il prodotto di fenomeni di sprofondamento (sinkhole) analoghi a quello verificatosi recentemente nei pressi di roselle, poco a nord di grosseto (berti et al., 2001). al riguardo, un’ipotesi che necessiterebbe di studi più approfonditi è che molti di questi sprofondamenti si siano formati durante l’ultima fase di basso eustatico, come conseguenza dell’abbassamento della superficie piezometrica, nelle zone ove sedimenti costieri avevano coperto aree di affioramento del calcare cavernoso. molte delle doline e delle depressioni presenti nelle zone sommitali a bassa pendenza sono legate a crolli di cavità sotterranee, alcune delle quali sono ancora parzialmente accessibili. le dimensioni arrivano a superare i 20 m di diametro con profondità sino a 35 metri. le depressioni più accentuate sono note come “bottini” e presentano spesso vani laterali la cui morfologia fa pensare ad un’origine in ambiente sommerso, per la presenza di alveolature e forme di corrosione tipo spongework sulle pareti. per quanto riguarda i fenomeni carsici più propriamente sotterranei, in tutta la zona sono note 57 grotte, concentrate per lo più nell’area del poggio del leccio. le dimensioni sono in genere modeste e non sono al momento conosciuti sistemi carsici complessi. la grotta più estesa è la grotta di punta degli stretti (numero catasto: 250/gr, fig. 7), che si apre sul bordo occidentale del monte argentario, a pochi metri dalla laguna di orbetello. questa cavità è costituita da fig. 6 a) distribuzione altimetrica (10 m) delle superfici a bassa pendenza (< 14 &) nell’area dei colli di capalbio. b) rapporto percentuale tra superfici a bassa pendenza e superficie totale per fasce di quota (10 m). a) altitudinal distribution (10 m) of low-gradient surfaces (< 14%) in the colli di capalbio area. b) percent ratio between low-gradient surface and total surface as function of 10 m altitudinal ranges. fig. 7 profilo schematico della grotta di punta degli stretti (250 t/gr). sketch profile of grotta di punta degli stretti (250 t/gr). rapporti tra morfogenesi ... 84 una galleria ad andamento orizzontale con brevi ramificazioni, che si sviluppa in corrispondenza del livello del mare attuale. la grotta è prevalentemente di origine epifreatica, dovuta a processi di dissoluzione a livello della tavola d’acqua, legati a fenomeni di miscelazione tra acque d’infiltrazione e acque salmastre. nelle parti iniziali della grotta sono presenti riempimenti clastici che ricoprono antichi corpi di concrezione di età non conosciuta (segre, 1959). nella grotta sono evidenti i segni di stazionamento del livello delle acque a circa 34 m di altezza, rispetto al livello attuale, riconducibile all’alto eustatico tirreniano. altre modeste cavità a sviluppo orizzontale si trovano nelle zone di versante del poggio del leccio, intorno a quota 200 m s.l.m. la maggior parte delle grotte ha però sviluppo misto. ad un primo tratto verticale, segue un tratto orizzontale od inclinato, che corrisponde al pavimento detritico di ambienti a camera, anche molto vasti, spesso di pianta ellittica. si tratta per lo più di cavità prive di ramificazioni, di forma emisferica, comunicanti con l’esterno tramite crolli che ne hanno interessato la volta. tra queste, la più ampia e profonda è il bottino della corbacchiara (1413/gr) che si apre con un grande pozzo di 35 m, che da accesso ad una vasta camera il cui pavimento scende sino ad una profondità di 73 m (fig. 8 e 9). le numerose grotte sottomarine, note soprattutto allo scoglio dell’argentarola e a giannutri (alvisi et al. 1987; alvisi & bruni, 1990) hanno dimensioni modeste ed andamento prevalentemente orizzontale. in molti casi sono chiaramente connesse con paleofalesie ora sommerse (fig. 10). da segnalare, infine, la presenza in molte cavità di riempimenti detritici costituiti da brecce con matrice rossastra, spesso bene cementate, ricche in molti casi di resti di grossi vertebrati erbivori (cervidi, equidi) e carnivori (canidi, felidi, ursidi, …) (fig. 11) che molti autori fanno risalire al pleistocene superiore (blanc, 1955; radmilli et al., 1955; segre, 1959; azzaroli et al., 1990) 5. morfogenesi della cavità carsiche da un punto di vista morfologico è possibile distinguere due tipi principali di grotte: cavità di forma grossomodo a camera, presenti soprattutto nelle zone sommitali a bassa pendenza, e cavità ramificate a sviluppo prevalentemente orizzontale. nessuna delle grotte, anche tra le poche a sviluppo prevalentemente verticale, ha le caratteristiche di cavità di percolazione o di paleo-inghiottitoi. grandi cavità a camera, prive di estese diramazioni laterali e non inquadrabili in sistemi di drenaggio sotterraneo di acque d’infiltrazione, sono di solito attribuite a fenomeni ipercarsici (sensu forti, 1993), per lo più dovuti a miscelazione localizzata tra acque a carattere chimico diverso, legate solitamente a risalita di acque termali, fenomeni di ossido-riduzione di mineralizzazioni o intrusione di acque marine (palmer, 1991). fig. 8 rilievo topografico del bottino della corbacchiara (1413 t/gr). topographic survey of bottino della corbacchiara (1413 t/gr). fig. 9 il grande ambiente alla base del pozzo d’ingresso del bottino della corbacchiara. the big chamber at the foot of the external pit of bottino della corbacchiara. n. iandelli & l. piccini un esame, peraltro non ancora completo, delle principali cavità carsiche non ha mostrato indizi di una loro possibile origine termale, come invece avviene per altre grotte della toscana meridionale, presenti in provincia di grosseto in contesti idrotermali ancora attivi (ad esempio presso roselle e saturnia). d’altra parte, la consistenza e la diffusione delle forme carsiche permette di escludere l’azione di acque rese aggressive da fenomeni di ossido-riduzione di mineralizzazioni, in particolare solfuri, presenti in alcune aree localizzate (monte argentario, capalbio) ma non al poggio del leccio, dove invece si segnala il maggior numero di grotte. queste considerazioni, insieme a diversi altri indizi di tipo morfologico, fanno propendere per un’origine in seguito a fenomeni di miscelazione tra acque dolci ed acque salate, o comunque in un contesto costiero. nel complesso, infatti, i diversi tipi di cavità si inquadrano bene in un modello di speleogenesi costiero (fig. 12) secondo il classico schema proposto da mylroie & carew (1990; 2000). le cavità a camera si sono probabilmente formate a livello della tavola d’acqua, in un ambiente prospiciente ad un’antica linea di costa, e in una situazione morfologica paragonabile a quella di alcune piattaforme calcaree, emerse o sommerse, attualmente presenti in aree tropicali (ad esempio florida, bahamas, yucatan). in questi contesti, risultano importanti anche i fenomeni di dissoluzione innescati da processi di degradazione di sostanza organica in condizioni anossiche, che portano alla formazione di h2s e che danno anche origine a quelle cavità note come blue hole (mylroie & carew, 2000). si tratterebbe quindi di fenomeni isolati, non connessi a veri sistemi carsici di drenaggio sotterraneo, che si sviluppano in corrispondenza di punti di maggior infiltrazione, spesso coincidenti con incroci di fratture. le cavità a sviluppo orizzontale, sovente ramificate, sono riconducibili ad almeno due generazioni. tale circostanza risulta dalla distribuzione altimetrica delle grotte ad elevato indice di orizzontalità, definito come il rapporto tra sviluppo planimetrico e sviluppo spaziale di una grotta (p i c c i n i , 1998), come mostrato nel grafico di figura 13. sopra il valore di 0,8, le grotte risultano suddivise in due gruppi ben distinti: il primo formato da 85 fig. 10 profilo batimetrico della scogliera sommersa in corrispondenza della grotta dei parapandulus, all’isola di giannutri, (da alvisi et al., 1987, modificato). batimetric profile of submerged reef close to the grotta dei parapandulus, at giannutri island (after alvisi et al., 1987, modified). fig. 11 le brecce ossifere, deposte sopra crostoni calcitici, che riempiono relitti di cavità carsiche all’isola di giannutri, presso cala maestra, . the bones breccias, laying on a calcite flowstone, filling relict karts caves in the giannutri island, at cala maestra. fig. 12 schema di formazione di cavità carsiche in ambiente costiero (da: mylroie & carew, 2000, modificato). formation of caves in coastal environment (after: mylroie & carew, 2000, modified). rapporti tra morfogenesi ... poche cavità relitte, situate intorno a 250 m di quota, con morfologie riconducibili a fenomeni di miscelazione in ambiente freatico lungo margini costieri; il secondo ubicato a quote inferiori e quindi più recente, formato da cavità a sviluppo orizzontale, situate in prossimità dell’attuale livello del mare o anche sotto a esso, e legate a fenomeni di miscelazione, innescati dal moto delle maree, in corrispondenza della tavola d’acqua, vale a dire in corrispondenza della linea di costa. le cavità sottomarine, per le quali, a dire il vero, non si hanno descrizioni morfologiche di dettaglio, sono da mettere in relazione a fasi in cui il livello del mare era più basso dell’attuale e contengono abbondante concrezionamento formatosi in condizioni vadose. su queste concrezioni sono state seguite datazioni u/th, che hanno dato, per un campione preso in una cavità dello scoglio dell’argentarola, età comprese tra 206 e 245 ka, riferibili dunque alle fasi di basso eustatico tra gli stadi mis 7.1 e mis 6.4 (bard et al., 2002). 6. conclusioni le particolarità morfologiche dell’area, unitamente ai caratteri speleogenetici delle cavità, permettono di riconoscere alcune tappe evolutive dei fenomeni carsici che si conciliano abbastanza bene con le ricostruzioni paleogeografiche proposte per il pliocene e il quaternario da diversi autori (ad esempio pasquarè et al., 1983; zanchi & tozzi, 1987). l’origine delle superfici sommitali a bassa energia del rilievo, presenti ad esempio al poggio del leccio, rimane, in mancanza di indizi geologici significativi, un problema aperto. una prima ipotesi è che in occasione della trasgressione pliocenica si sia formata una vasta piattaforma d’erosione marina, che interessa l’insieme di isole di natura prevalentemente carbonatica in cui è suddivisa la porzione meridionale della dorsale mediotoscana. l’origine di questa piattaforma può essere stata favorita dalla litologia e dalla elevata permeabilità delle brecce carbonatiche. in queste condizioni si hanno, infatti, fenomeni di corrosione per miscelazione a livello della tavola d’acqua, che agiscono anche lontano dai margini costieri. questi processi danno origine a cavità ramificate che, una volta che sono intercettate dall’arretramento delle falesie, facilitano il lavoro di smantellamento del moto ondoso. non si può tuttavia escludere che la morfologia dolce delle zone sommitali, nelle zone di affioramento del calcare cavernoso, sia in parte ereditata dalla conformazione originaria del tetto di questa formazione o essere anche il prodotto di processi di modellamento in ambiente continentale durante le prime fasi di messa a nudo della successione toscana. durante il pliocene superiore, le aree carbonatiche sono smembrate dalla tettonica e sollevate in modo differenziale. alcune porzioni sono depresse sotto il livello del mare, mentre su quelle che vanno progressivamente sollevandosi si sviluppano forme carsiche legate alla presenza di una tavola d’acqua in prossimità della superficie, nonché cavità costiere ai margini. il sollevamento, che prosegue anche nel pleistocene, porta porzioni del plateau calcareo sino a 250-300 m di quota, conservati nelle superfici sommitali a bassa pendenza del poggio del leccio. nel pleistocene medio-superiore, si ha probabilmente l’esumazione e lo smantellamento delle forme carsiche più antiche in corrispondenza delle superfici sommitali e dei versanti a controllo strutturale. lungo le linee di costa si ha invece la formazione di una nuova generazione di cavità costiere, in corrispondenza della recente zona di oscillazione eustatica del livello del mare. terrazzi e cavità carsiche legate a questa fase, sono attualmente dislocati sino a 70 m di altezza sul livello del mare attuale lungo le coste meridionali del m. argentario. secondo alcuni autori ciò potrebbe essere attribuito ad un basculamento verso n pre-tirreniano che ha interessato l’argentario (grauso e zarlenga, 1991). in effetti, la morfologia del monte argentario si differenzia notevolmente da quella del poggio del leccio e dei colli di capalbio, anche in situazioni con litologia simile, indicando una maggiore attività morfodinamica legata sia alla maggiore esposizione ai processi d’erosione litorale sia, forse, ad un sollevamento più marcato e disomogeneo. dati cronologici in grado di chiarire meglio la successione temporale delle fasi principali di sviluppo dei fenomeni carsici, al momento solo abbozzate, potranno venire dallo studio e dalla datazione dei riempimenti clastici, in particolare quelli fossiliferi, e dalla datazione con metodi radiometrici delle concrezioni, previsti per il proseguimento di questo studio. ringraziamenti si ringraziano il prof. carlo bartolini e il prof. ugo sauro per gli utili suggerimenti e il lavoro di revisione del primo manoscritto. bibliografia azzaroli a., borselli v., rustioni m. 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(1987) evoluzione paleogeografia e strutturale recente del bacino del fiume albegna (toscana meridionale). geologica romana, 26, 305-325. 87 ms. ricevuto il 10 maggio 2006 testo definitivo ricevuto il 10 ottobre 2006 ms. received: may 10, 2006 final text received: october 10, 2006 rapporti tra morfogenesi ... late quaternary evolution of the terni basin, central italy: new geoarchaeological data milena bertacchini dipartimento di scienze della terra, università di modena e reggio emilia, modena e-mail: milena.bertacchini@unimore.it abstract: bertacchini m., new geoarchaeological data on the recent evolution of the terni basin, central italy. (it issn 0394-3356, 2009). because of an archaeological find of part of a hellenistic city wall (ca 5th -3rd century bce) a well-preserved 10 m thick fluvial sequence was studied close to the centre of the town of terni, in an area of central italy (umbria) where the geological outcrops are generally scarce. this study was made in a large excavation for a building that permitted direct observation of the sediments that filled the terni basin and provided a step forward in our knowledge of its geoenvironmental evolution. the sedimentary sequence was deposited by a segment of the ancient nera river-course (paleo-nera) in the late pleistocene-early holocene and its presence is correlated with the development of the first human settlements in the town of terni. this fluvial sequence shows evidence of a low-sinuosity gravel meander system consisting of transverse gravel bars and gravel sheets in its lower part, that are capped by a 5 m thick levee unit and overbank deposits interbedded with incipient paleosols and a crevasse channel unit. the floristic composition contents in the paleosols of the overbank sequence provide important information on the climatic transition from the late glacial to the holocene. the upper part of the sequence, a paleosol dated with archaeological remains to roman times, contains important elements that aid in understanding the development of the first phases of urbanisation of the ancient town of terni. riassunto: bertacchini m., nuovi dati sull’evoluzione recente della piana di terni (italia centrale). (it issn 0394-3356, 2009). lo scavo ad uso civile realizzato nel sito di corso del popolo, nei pressi del centro storico di terni, ha permesso la diretta osservazione di una potente successione sedimentaria di ambiente fluviale deposta a partire dal tardo pleistocene da un antico tratto del fiume nera (paleo-nera). lo studio di dettaglio condotto sulla successione esposta ha rappresentato una importante opportunità per la raccolta di nuove informazioni sull’evoluzione geologico-ambientale recente del bacino di terni, attraverso indagini di tipo geologico-sedimentologico, mineralogico-petrografico, paleontologico e pollinico, affiancate da dati archeologici. la base della successione è rappresentata da sedimenti ghiaiosi di canale attivo passanti a depositi di esondazione con sequenze di argine, di canale di rotta e di canale di crevasse, intervallati da paleosuoli interessati da una pedogenesi poco evoluta. la variazione del contenuto pollinico registrata all’interno dei depositi di esondazione è da imputare al cambiamento climatico legato alla fine del tardi-glaciale ed all’inizio dell’olocene. l’abbandono del canale fluviale favorisce la formazione di un lago poco profondo o acquitrino e la deposizione di sedimenti carbonatici fini interrotti a tetto da un paleosuolo archeologicamente riferibile al i sec. a.c. i dati stratigrafici e cronologici ottenuti dallo studio della sequenza investigata concorrono a ricostruire con maggior puntualità la situazione geo-ambientale che accompagnò le prime fasi di urbanizzazione della città di terni. keywords: fluvial deposits, paleosols, holocene, terni, central italy. parole chiave: depositi fluviali, paleosuoli, olocene, terni, italia centrale. il quaternario italian journal of quaternary sciences 22(2), 2009 249-256 introduction the terni plain is located in the southern part of the umbria region, within the central and terminal sectors of the nera river basin (fig. 1). it is a transition area between the inner apennine chain and the hills and plains of the western regions of italy in the tiber valley (southern and northern etruria). the stratigraphy of the continental deposits filling the terni basin is not well-known because of the scarcity of useful outcrops. the entire continental succession, which characterises the recent sedimentary deposition of the plain, is largely hidden below the surface. most of the detailed subsurface geological data collected has come from archaeological or civil excavations and the results of recent studies of the sediments in the terni basin (be r t a c c h i n i et al., 2006; fa z z i n i & ma f f e i, 2006) have not permitted a recognition of the continuous stratigraphic succession, mainly formed by lacustrine and fluvial-lacustrine sediments, deposited from the vii century bce until roman times. in this framework the sequence here studied is fundamental for the knowledge of the sediments filling the terni basin and for better understanding both the geoenvironmental evolution of the plain and the development of the first human occupation in the centre of terni. the terni plain has continuously been a major communication and trade passageway since the bronze age, because of its morph o lo gi cal an d s t ra t egi c g eo g ra ph ic al lo cat i on (giontella, 2006). the town of terni was formally founded in the 672 bce (bonomi ponzi, 2006), even though the oldest significant phase of its urban development was in the 3 rd century bce, in coincidence with the roman expansion in the umbria region (pe r i s s i n o t t o, 2006). the ancient name of terni, interamna nahars, means “between two rivers”, was given because its position at a confluence of the nera river with the serra-tescino stream suggesting a different hydrographic layout at that time. several authors have hypothesized that both streams have probably changed their courses through time (grassini, 1947; fontaine, 1990; fazzini & maffei, 2006), on the basis of archaeological data (fig. 1). this paper presents the data obtained of a verti250 m. bertacchini cal s eq u en ce o f s ed ime n t s exposed by a civil excavation (over 50 m wide) conducted in summer 2006 along corso del popolo road, close to the centre of terni, which has given us an insight as to the morphologic grounding of this newly founded city in its earliest days. geological setting the terni plain is one of the fault-bounded intermontane basins formed during the plioquaternary succession of tectonic phases in an extensional regime, which affected the centr al po rt ion of t h e n ort h ern apennine chain (ba r c h i et al. , 1991; ca t t u t o et al., 1992; ca v in a t o et al., 1993; br o z z e t t i & lav e c c h i a, 1995). accordingly, the elongated nne-ssw shape of the terni basin results from the complex in te ract ion o f th e martani, sabini and val di serra fault systems boardering the plain (bo n i n i, 1997; gi r o t t i & ma n c i n i, 2003). the terni basin is considered to be the western elongation of the tiber basin, an intermontane apenninic depression that was gradually filled with fluvial and lacustrine deposits (lo t t i, 1917; li p p i bo n c a m b i, 1960; am b r o s e t t i et al., 1978; ba s i l i c i, 1993; am b r o s e t t i et al., 1995; co n t i & gi r o t t i, 1977; girotti & mancini, 2003). a shallow lake or pond system occupied the terni basin up to earliest historical times that gradually disappeared due to the alluvial infill from the nera, serra and tescino streams (bertacchini et al., 2006; fazzini & maffei, 2006). the terni basin is flanked by martani-reatini mountains to the east and amerini-narnesi-sabini mountains to the west. these higher areas consist of calcareous meso-cenozoic units of the umbria-marche marine succession, where the headwaters of the nera river and its main tributaries are located (the aia and serra-tescino streams and the bianco-caldaro brook). the predominance of carbonate rocks in this apennine area greatly control the composition of the sediments transported by the watercourses into the terni basin as well as the groundwater composition of the region. methods preliminary data here presented results from a sedimentological and physical study of the sediments in order to integrate the detailed visual inspection of the deposits and define the lithostratigraphical sequence. these data are a combination of: lithology, grain size, sedimentary structures, colour and any other possible diagnostic element. colour definitions, such as 2.5 y 5/4, are referred to munsell colour soil chart and consists of hue (2.5 y), lightness (5), and chroma (4). ams (accelerator mass spectrometry, nelson et al. 1977; bennett et al. 1977) radiocarbon datings have been carried out from carbon organic remains in the beta analytic inc. laboratory in miami, florida. the datings refer to the intcal04 calibration data set for terrestrial samples (reimer et al., 2004). the first results on paleontological (macro and micro) and pollen characters cited in this paper have been supplied by personal communications respectively from a. russo and s. marvelli. the paleontological samples have been treated with h2o2 (2% vol.) and the observations have been carried out on a dry residue, sieved and desiccated in oven at 105 °c. the pollen analysis have been carried out following the standard procedure described by lowe et al. (1996) in the archaeoenvironmental giorgio nicoli laboratory in bologna. the micromorphological study on paleosol thin sections have been examined under the optical microscope applying the methods of stoops (2003) and some terminology of bu l l o c k et al. (1985) and br e w e r ( 1 9 7 6 ) . m in eralo gic al an aly ses on pebbl e coat in gs observed in the sequence have been conducted by energy-dispersive x-ray (edx) technique coupled with an environmental scanning electron microscope esem quanta-200 in the modena university cigs laboratory. the sedimentary sequence of the corso del popolo site this study is based on observations made during the excavation of the corso del popolo car park located fig. 1 morphological and geographical location of the town of terni. this map contains the present-day hydrographic system and the stream-course changes both of the nera river, according to this study and that of fontaine (1990), together with data concerning the serratescino stream, according to grassini (1947), fontaine (1990) and fazzini & maffei (2006). the confluence of the serra-tescino stream with the nera river during medieval times has been suggested by grassini (1947) and fontaine (1990). ubicazione geografica della città di terni e rappresentazione cartografica semplificata del suo territorio. nella mappa è ricostruita la paleoidrografia dei principali corsi d’acqua dell’area: il fiume nera, sulla base dei risultati presentati in questa ricerca e dei dati pubblicati da fontaine (1990); e i torrenti serra e tescino, come riportato da grassini (1947), fontaine (1990) e fazzini & maffei (2006). near the centre of terni, not far from the present-day course of the nera river. the examined section has permitted the reconstruction of a 10 m thick sedimentary succession, which was deposited by the watercourse antecedent to the modern nera. a detailed multidisciplinary stratigraphical investigation has been carried out based on geological, mineralo g ica l, pet r og r aph i cal micr o mor ph o lo g ica l an d paleontological evidences alo n g wi t h p ol len an d archaeological data. four main different un it s h ave been re cog n i zed in t h e investigated sequence. unit a, at the base of the excavation, consists of a 3 m t h ic k s e dime n t ary sequence mainly composed of gravel with subordinate pebbly-sand and sand. this unit, whose lower limit is not exposed, abruptly passes to a finer deposit of the overlying unit b. the sedimentary structures observed in these deposits are mainly represented by t rough -sh aped an d pla n ar cr os s be ds , which develop in a meterlong continuous sets. the gravels are generally moderately sorted. they are composed of rounded to subro u n ded cal car eo u s an d ch er t y, med iu m t o l arg e pebbles , rang ing 1 ÷3 cm (mean diameter). unit s of single depositional events are in sets about 40 cm thick and an angle of about 20°, suggesting a main watercourse flow from ne to sw. the gravels are clastsu ppo rt ed w it h les s t han 10% smaller sized clasts of san d an d mu d as matr ix. peb ble s a re c oa t ed by a reddish-black thin iron-manganese film and there is very lit t l e mat r ix bet w een t h e clasts. horizontally bedded gravel sheets are present in the upper portion of unit a. they are formed of rounded medium to very large pebbles and subordinate cobbles , s li gh t ly imbr ica te d. they appear as moderately sorted, graded, clast-supported deposits with subordinate sand and mud. unit b overlies unit a and is formed by a 5 m thick 251late quaternary evolution of the terni basin, central italy: ... sequence consisting of a well-developed cyclicity, which is cadenced by dark brown levels presenting pedogenic modification. each cycle is characterized by a basal sandy unit overlain by a pedogenised horizon of coarser-grained sediment (b1) or of finer-grained sediment (b2). each simple pedofacies sequence (kr a u s, fig. 2 stratigraphic section studied in the corso del popolo site of the terni basin. the different units are described in text. a: unit a, related to coarse-grained point bar deposits; b: unit b, an overbank sequence formed of levee (b1) and crevasse-splay (b2) sediments interbedded with floodplain deposits; unit c, a crevasse channel deposit; c: unit d, sequence due to a cut-off event. ricostruzione della successione stratigrafica del sito di corso del popolo a terni. sono indicate le diverse unità come descritte nel testo. a: unità a, caratterizzata da sedimenti ghiaiosi di canale attivo; b: unità b, depositi di esondazione con sequenze di argine (b1) e di canale di rotta (b2) intervallati da paleosuoli interessati da una pedogenesi poco evoluta; c: unità c: deposito di canale di crevasse; d: unità d, depositi dovuti alla formazione di un lago poco profondo o acquitri no conseguente all’abbandono del canale fluviale. 252 1987) is capped by the base of the ensuing cycle with little or no erosion; except the top of unit b, which was truncated by the erosive deposition of unit c (fig. 2). the simple pedofacies sequence (b1) is made of coarsening-upward cycles of fine sandstones and siltstones showing weakly identifiable ripple-cross lamination and matrix-supported graded gravel deposits formed of brown-reddish pebbles and cobbles. the gravel levels have been affected by pedogenic modification including root structures, scattered desiccation cracks and mottling. these pedofeatures have also been examined in a thin section where, when mottling is present, there is a clearly visible considerable scattered enrichment in interstitial oxides of iron and manganese. this weakly developed pedogenic modification has been observed in the gravel layers of b1 in association with unaltered parent material characterized by sandstones, siltstones and lithic fragments. the lowest gravel layer in b1 has been studied in greater detail to obtain a better understanding of the relations between unit b and the underlying unit a. the finer sediment in the lower part of this horizon is dark brown (7.5 yr 3/2-4) and yellow brown mottled (10 yr 5/6), passing to yellow-reddish brown mottled (7.5 yr 5/6) in the upper part. the second and relative younger dark brown (10 yr 4/2) gravel layer in b1 (fig. 2) is indicated by prevalent amounts of pedogenic modification that is, however, more immaturely developed; mottling is observed but desiccation cracks are not present. a determination of the absolute age through asm radiocarbon dating has yielded a value of 9310±50 bp (10660-10310 cal bp; beta-238366). the pollen data of the base of b1 have revealed a moderate presence of deciduous oaks with f r a x i n u s in an open landscape and a high content of non-arboreal pollen (cichorioideae). at the top of b1, arboreal vegetation u n d e rwent a clear reduction, without disappearing completely. the simple pedofacies sequence b2 overlies b1; it is formed by fining upward cycles of laterally discontinuous exposure sheet-like siltstones and very-fine sandstones, interspersed with dark-coloured pedogenised mudstones (10 yr 5/2; 4/2). each cycle of sandy layers capped by a single paleosol is repeated at least six times moving upward b2, with a range in thickness of each one from 0.4 to 1 m. no erosional surfaces are observed between two subsequent cycles, passing upward b2. the last cycle at the top of b2, and corresponding to the top of unit b, is truncated and eroded by a channelized-shape gravel deposit (unit c). in general, the sediment forming the base of each series consists of a beige-coloured (10 yr 6/4; 7/2-4; 8/4-6) calcareous sandy siltstone or fine sandstone that passes upwards to a fine siltstone. the primary structures are generally not preserved but, where identifiable, they present cross and horizontal lamination. the top of each cycle is dominated by crumbly calcareous mudstones on which a single paleosol profile (freytet, 1973), with an immature pedogenic evolution, develops. these paleosols present dark brown coloured zones with burrowing, root traces, rare calcite nodules, and bacterial concretions. the micromorphological data confirm the pedofeatures observed in outcropping and show the correlation between root traces and calcite nodules, when the nodules are present. the paleosol of the uppermost cycle b2 was not truncated, and lies at the base of the gravel channelized-shape deposit. it is the only horizon to show rare papulae pedofeatures (brewer, 1976) in a thin section. this deposit has a radiometric age of 8010±40 bp (9010-8730 cal bp; beta-238365). an appreciable vegetation change occurred at the beginning of the deposition of the simple pedofacies sequence b2, mainly due to the early appearance of tilia and salix, while the landscape was still fairly open. moving upward along the sequence, the pollen content increases, both in quantity and diversity of species; the deciduous oaks accompanied by several other arboreal taxa (fraxinus, tilia, carpinus, pinus, salix, alnus ecc.) define a forested landscape. the upper part of unit b is engraved and eroded by a coarse-grained channelized-shape deposit, here indicated as unit c (fig. 2). unit c appears as a lens, a few meters wide and one meter thick, with gentle flanks and an erosive concave base. the channel-filling is formed by moderately sorted to well sorted graded coarse to pebbly sands up to pebble gravels. the finer sediments at the base of the channel present ooids and tubular bacterial structures and show trough cross bedding (mi a l l, 1996). penetrative rhizolite laminar calcretes are present, due to the calcification around roots (wr i g h t et al., 1995). these are 3-5 cm thick and 40 cm long and develop along the main cross-bedding surfaces. they correspond to beige calcareous cementation normally developed around root mats and show alveolar septal structures in a thin section (wright et al., 1995). a pebble to cobble gravel sheet closes the coarsening upward channel-filling and exhibits a slightly convex shape. unit d constitutes a 4 m thick sequence characterized by calcareous, gold-coloured (10 yr 8/2-3), fine siltstones with faintly planar lamination at the base. this deposit continues at the base of the upper section examined at the corso del popolo site. in about two meters of thickness it is possible to observe siltstones or mu d st o n es w it h os t r aco ds a n d p u lmo n at e gastropods (in course of determination), bioturbation, root tubules and carbonate concretions. at the top of the sequence there is a yellow brown (2.5 y 5/4) mottled paleosol containing archaeological remains that accumulated before the 1s t century bce (superinten dence to archaeological properties of umbria, personal communication). an important structure, part of a huge wall of hellenistic age (5t h3r d century bce) has been found above the muddy sandstones with ripple lamination on the northern side of the site excavation. the presence of significant human exploitation of the corso del popolo area since that time has probably contributed to erase all other parts of that wall. interpretation integrating lithological, sedimentological, mineralogical aspects with physical evidence and paleontological and pollen data, allows us to reconstruct a reasonable picture of the alluvial environment where the continental studied succession accumulated. each unit is related to characteristic depositional processes. m. bertacchini 253 unit a shows sediments and sedimentary structures deposited by fluvial processes in an alluvial plain, probably due to the accumulation of lag deposits within transverse gravel bars and horizontal beds (lithofacies gp, gt and gh of mi a l l, 1996). according to jackson (1 9 7 6 ) , gu s t a v s o n (1 9 7 8 ) a n d m i a l l ( 1 99 6 ) , t h is sequence is probably related to a coarse-grained point bar deposit characterized by lateral accretion and gravel bedform elements. extensive continuous sets of trough cross-strata are interpretable as due to a moderately stable bar related to a gravel-bed wandering fluvial system (as h m o r e, 1991; wo o l d r i d g e & hi c k i n, 2005). such an important supply of coarse-grained gravelly sediments requires the effects of intense physical weathering processes and extreme ranges in fluvial discharge to favour their deposition. post-depositional movement of fluids through the sediments also caused intense fluid washing with a concomitant removal of most fine-grained sediment, therefore little matrix remains. unit b shows a coarsening-upward simple pedofacies sequence at the bottom (b1), which is overlaid by a fining-upward simple pedofacies sequence (b2), both are interbedded with incipient paleosols. unit b developed in a floodplain area proximal to the active channel. it corresponds to a vertical sequence of overbank environments constituted by progressive sandy levee (b1) and crevasse-splay (b2) sediments associated with finer-grained floodplain deposits. the passage between unaltered fluvial sediments and paleosols is apparently related to an alternating succession between periods of flood events and periods of quiescence without fluvial sedimentation. the sequence b1 suggests relatively rapid accretion rates on the basis of poorly developed pedogenic modification. the paleosol at the base of this unit can be interpreted as an entisol that, even though immature, testifies to a slight decrease in the sedimentation rate (kraus, 1987). the strong presence of burrowing, rooting and calcite nodules as pedogenic features in the paleosols observed in the sequence b2, hints that the deposition of new sediments were relatively frequent over a period of time but sufficiently infrequent as to permit the triggering of such aspects of pedogenic modification. the pollen assemblage of the lowest part of b1 is interpreted as representing a semi-arid and cool phase where moderate deciduous oaks dominated the open landscapes. the marked vegetational reduction recorded at the top of b1 suggests a worsening of the severe climatic conditions. moving upward b2, a significant vegetational change is marked. the appearance of tilia and salix at the base and a significant expansion of tilia and various other tree taxa at the top of the sequence, evidence a more temperate and humid climate than in the previous phase. unit c marks a limited erosive event, which cut the top of unit b sequence. it is characterized by a coarse-grained lens deposited by a crevasse channel, which probably is correlated to the sediments of the cut-off event of unit d. the penetrative rhizolite laminar calcretes, which occurred as calcareous cementation around root mats, suggest a carbonate-rich groundwater environment ass ociated to an in crease of t emperature, wh ich favoured the calcium-carbonate precipitation. unit d is associated with a shallow lake, pond or marshy environment overlies a structure that represents a probable cut-off process from the active streamchannel (sm i t h et al., 1989; wi l l i s & be h r e n s m e y e r, 1994; miall, 1996). unit d represents the beginning of a new geoenvironmental situation favouring the development of a shallow carbonate lacustrine-palustrine environment related to a shallow, fresh-water lake (platt & wright, 1992) and a more humid climate. this interpretation is also based on the first results obtained from fossil species present in the sediments at the bottom of unit d. the degree of pedogenic modification increases upwards in the sequence. discussion of the results t h e s ed imen t s an d se dime nt ar y s t r u ct u res observed in the corso del popolo fluvial succession on the terni plain are representative of an ancient stream course, flowing on the eastern side of the present-day town of terni. the collected data suggest that this stream acted as an ancient segment of a paleo-nera river located close to the west of the present-day course of the nera river. this geological result proves the change in the nera river-course originally hypothesised by fontaine (1990) on the basis of archaeological speculations (fig. 1). the studied sequence represents a rare example of a continuous succession deposited from the late ple is t o cen eear ly ho lo ce n e u p t o r om an t imes observed in the terni basin. fig. 3 hypothesis of reconstruction of the oldest defensive wall built around the centre of terni during the 5th-3rd century bce (mod. zampolini faustini, 2006) schema ricostruttivo della cinta muraria a difesa dell’antica città di terni tracciato sulla base del rinvenimento del tratto di muro ascrivibile al v-iii sec. a.c. citato nel testo (mod. zampolini faustini, 2006). late quaternary evolution of the terni basin, central italy: ... 254 the detailed analysis of the sedimentary succession show an interesting geoenvironmental evolution of the basin, passing from a coarse-grained point bar sequence deposited by a low-sinuosity fluvial system (unit a), grading to an overbank succession composed of levee deposits (b1) and crevasse-splays (b2), cyclically interrupted by immature paleosols. a crevasse channel (unit c) truncates the overbank deposits and marks the transition to a shallow lacustrine-palustrine environment related to a cut-off event. the ams radiometric dating determined at the base of unit b links the visible part of unit a to the effects of the final phases of the last glacial portion of late pleisto cene (bu s s c h e r s et al., 20 07) , wh ich favoured the large supply of the coarse-grained sediments forming unit a. a late glacial climatic situation which is comparable with the last glacier advance of the gran sasso massif in the central apennines dated by giraudi & frezzotti (1997) at ca. 11000 yr b.p. the sequence of the overbank deposits (unit b), in spite of their laterally discontinuous exposure, suggests that deposition occurred in a relatively proximal position with respect to the paleo-nera river-channel, starting from 9310±50 bp (10660-10310 cal bp). the overbank sequence was generated by sporadic flood events followed by pedogenesis, which was periodically in terrupted by crev as sesplay depos ition un til 8010±40 bp (9010-8730 cal bp), when a crevasse channel (unit c) cut the sequence and ended the overbank deposition. the pollen assemblage and the forest reduction recorded in the lower part of unit b is related to a semiarid and cool phase. this was successive the marked vegetational fluctuation proved at rieti basin (ri c c i lu c c h i et al., 2000) and at lagaccione, near lago di bolsena, until a few centuries after 10850±105 yr b.p. (magri, 1996), and which the authors consider related to the younger dryas event. the vegetation associated to the upper part of unit b suggests a progressive considerable forest expansion, which is interpretable as due to a more temperate and humid climate. the increase of arboreal plants marks the transition to holocene as observed in oth er s ites of cen t ral i taly (f o l l i e r i et al., 19 89 ; calderoni et al., 1994; watts et al., 1996; magri, 1999; magri and sadori, 1999; ricci lucchi et al., 2000). palustrine-shallow lacustrine and calcareous sediments close the corso del popolo sequence (unit d) were deposited in a cut-off shallow lake or pond environment related to a temperate wet climate, where the rising temperature was favourable to the deposition of the calcium-carbonate. similar environmental conditions are documented at rieti basin (ricci lucchi et al., 2000), lagaccione (ma g r i, 1999) and lago di vico (magri & sandori, 1999) during the interval 8000-7000 yr bp. the environmental changes recorded in the sediments of the terni sequence from the middle holocene were a consequence of climatic changes affected by regional and local factors. it is more difficult to put forward a reconstruction hypothesis based on the scarce remains of the wall of hellenistic age (ca 5t h 3r d century bce) found at the corso del popolo site. this wall apparently represented a portion of the eastern side of the oldest defensive wall built around the town of terni, at the beginning of its roman political organization (fig. 3). conclusions fluvial systems may contain important archives for improving the understanding of present and past landscape stability. the wide fluvial sequence of the corso del popolo site on the terni plain is an u nus ual occas ion t o observe a well-preserved sediment record of an ancient course of nera river starting from the late pleistocene. detailed analyses of the geometry and internal lithological variation of the fluvial succession, as well as the pedogenic features and pollen assemblages of alluvial paleosols in the overbank deposits, have permitted a more detailed reconstruction of the recent geoenvironmental evolution of the terni plain to be improved and, meanwhile, some historical and archaeological speculations concerning the ancient hydrographic system of the town of terni to be addressed, even in a humble site such as a future car-park. considering the vertical evolution of the sedimentary sequence recorded in terni, it is possible to relate the sedimentological and ecological evidences observed to significant changes in climatc conditions due to the transition between the last phases of late glacial times and the more temperate and humid beginning of the holocene. these results are in agreement with the records from ot her sites in central italy: valle di cas t ig li on e ( f o l l i e r i e t a l. , 1 9 8 9 ) , l ag o l u n g o (calderoni et al., 1994), lago albano (lowe et al., 1996), lagaccione (ma g r i , 19 99), lago di vico (ma g r i & sadori, 1999), rieti (ricci lucchi et al., 2000). the terni site can be considered an important archive of paleoenvironmental and paleoclimate record for the global climatic transition from the end of the last glacial times to the beginning of holocene, while the ensuing climatic changes recorded in the sediments were progressively affected by regional and local environmental factors. acknowledgements i wi s h t o t h an k l a u ra b o n om i po n zi o f t h e su perintendence to arch aeological propert ies of umbria who made this research possible, and terni corso del popolo spa which supported the work. i am grateful to b.c. schreiber for constructive comments and the revision of the manuscript and to d. brunelli and d. fontana for useful suggestions. paleontological data were carried out by antonio russo (university of modena and reggio emilia); pollen analysis was realized by marco marchesini and silvia marvelli (laboratorio archeoambientale-centro “g. nicoli”, bologna). references ashmore p.e. 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(1995) a classification of rhizogenic (root-formed) calcretes, with examples from the upper jurassic-lower cretaceous of spain and upper cretaceous of southern france. sedimentary geology, 100 (1-4), pp. 143-158. zampolini faustini s. (2006) topografia ed urbanistica di interamna nahars tra vecchi dati e nuove scope r t e. in: angelelli a. e bonomi ponzi l. (a cura) terni interamna nahars. nascita e sviluppo di una città alla luce delle più recenti ricerche archeologiche. école française rome, pp. 141-161. 256 ms. ricevuto il 23 aprile 2008 testo definitivo ricevuto il 28 ottobre 2008 ms. received: april 23, 2008 final text received: october 28, 2008 m. bertacchini imp.forno&lucchesi la successione fluviale terrazzata pleistocenica dei versanti occidentale e nordoccidentale della collina di torino maria gabriella forno1 & stefania lucchesi2 1dipartimento di scienze della terra, università di torino 2c.n.r. istituto di geoscienze e georisorse, sezione di torino riassunto: forno m. g. & lucchesi s., la successione fluviale terrazzata pleistocenica dei versanti occidentale e nordoccidentale della collina di torino. (it issn 0394-3356, 2005). gli studi precedenti riguardanti l’evoluzione geologica quaternaria della collina di torino hanno consentito di evidenziare in modo preliminare le tracce di un reticolato idrografico pleistocenico, sensibilmente sospeso e con andamento molto differente rispetto ai corsi d’acqua sviluppati attualmente nel rilievo collinare. il rilevamento geologico dei versanti occidentale e nordoccidentale effettuato in occasione del presente studio, i cui risultati sono riassunti nella carta geologica alla scala 1:20.000 allegata, permette di ricostruire con maggiore dettaglio la distribuzione della successione fluviale conservata sulle sommità delle dorsali spartiacque. il riconoscimento dei diversi termini di questa successione, distribuiti in corrispondenza a differenti fasce altimetriche, è facilitato dalla loro espressione morfologica: corrispondono a lembi di superfici terrazzate con estensione compresa tra alcune migliaia e alcune decine di migliaia di m2, spesso evidenziati dalla presenza di antichi edifici residenziali, e localmente a più estesi relitti di meandri incastrati. l’estrema antropizzazione dell’area e la diffusa copertura eolica e colluviale rappresentano invece un ostacolo all’analisi sul terreno. malgrado le difficoltà incontrate, l’estremo dettaglio con cui è stato effettuato il rilevamento geologico ha consentito di riconoscere corpi sedimentari di origine fluviale, con spessore metrico, in corrispondenza alla maggior parte dei lembi descritti; localmente tali forme sono risultate invece modellate direttamente sui termini marini terziari. i numerosi lembi sono stati distinti tra loro e correlati in base al differente sviluppo altimetrico e alla diversa alterazione dei sedimenti, che hanno consentito il riferimento cronologico dell’intera successione all’intervallo di tempo corrispondente al pleistocene medio e superiore. l’attuale assetto altimetrico delle forme relitte, variamente sospeso rispetto alla pianura con un dislivello compreso tra 20 e 400 m, la loro distribuzione complessiva, in corrispondenza alle attuali dorsali secondo fasce allungate parallelamente allo spartiacque collinare, e l’allungamento prevalente dei singoli lembi, svincolato dall’andamento dei corsi d’acqua attuali, suggeriscono il legame con una situazione morfologica e geologica del rilievo collinare notevolmente diversa dall’attuale. e’ possibile in particolare ipotizzare lo sviluppo di corsi d’acqua con andamento circa parallelo allo spartiacque principale: l’impostazione estremamente recente dell’attuale f. po al margine nordoccidentale del rilievo collinare, già documentata in letteratura, indica che le tracce prese in esame sono invece da collegare a precedenti andamenti del reticolato affluente; lo studio mineralogico dei sedimenti, oggetto di un lavoro specifico tuttora in corso, consente di ipotizzare una alimentazione essenzialmente dai bacini dei fiumi dora riparia e stura di lanzo. lo sviluppo altimetrico anomalo dei lembi fluviali relitti e la presenza di scarpate con altezza di alcune decine di metri tra i diversi ordini suggeriscono una successione di episodi di approfondimento erosionale del reticolato idrografico, connessa con il sollevamento recente dell’edificio collinare. la successione terrazzata esaminata rappresenta quindi il risultato della progressiva deformazione del settore distale dei conoidi alpini, coinvolti nel sollevamento della collina di torino e nella migrazione verso nw del suo margine esterno, che hanno portato al loro inglobamento nell’area collinare. si può stimare che tale deformazione, tutt’ora in atto, abbia avuto, nell’intervallo compreso tra il pleistocene medio e l’olocene, una componente verticale con velocità media di sollevamento relativo di circa 1 mm/anno abstract: forno m. g. & lucchesi s., the fluvial pleistocenic terraced succession of w and nw slopes of the collina di torino. (it issn 0394-3356, 2005). previous studies about the quaternary evolution of the collina di torino put in evidence in a preliminary way traces of a pleistocenic hydrographic net, suspended and with a different pattern from the watercourses now developed in the relief. the geological survey of the western and northwestern slopes carried out during the present study, synthesized in the attached geological map at 1:20.000 scale, allows a more detailed reconstruction of the distribution of the fluvial terraced succession preserved on the secondary watersheds. the identification of the various relics of the succession, distributed with different elevations, is suggested by its morphology: they correspond to terraced surfaces with an extension between some thousands and some tens of thousands of m2, often underlined by ancient buildings, and locally to wider remains of embedded meander. the local manmade modifications of the area and the loess and colluvial covers are instead obstacles for the field work. despite these difficulties the extreme detail used for the geological survey allows the recognition of fluvial sedimentary bodies, some meters thick, associated with the main described shapes: locally the terraced surfaces appear modelled directly on the tertiary marine sediments. the different shapes are identified and correlated by the elevation and the alteration degree of the sediments, suggesting the chronological reference to the middle and upper pleistocene. the present elevation of the remains, suspended from 20 to 400 m on the plain, their distribution in the present ridges along strips parallel to the main watershed and their elongation, different from the present watercourses, suggest a link with a very different morphological and geological situation of the relief. in particular it can be supposed the trend of watercourses parallel to the main watershed: the extremely recent setting of the present river po along the northern boundary of the relief, already known by literature, shows that the examined remains are instead connected to a previous trend of the hydrographic net; mineralogical analysis, still in progress, suggest an alimentation particularly from the stura di lanzo and dora riparia basins. the anomalous elevation of the fluvial succession and the presence of scarps some tens of meters high between the different orders of terraces suggest a succession of erosional deepening episodes of the hydrographic net, connected to the uplifting of the collina di torino. the examined terraced succession represents the result of the deformation of the distal sector of the alpine fluvial aprons, involved in the uplift of the turin hill and in the northwestern migration of its external margin, and their embedding in the hilly area. it can be supposed that this deformation, still in action, had a rate of uplift of the order of 1mm/yr from the middle pleistocene to the holocene. parole chiave: collina di torino, depositi fluviali, deformazione, pleistocene. keywords: collina di torino, fluvial sediments, deformation, pleistocene. il quaternario italian journal of quaternary sciences 18(2), 2005, 123-134 124 g. forno & s. lucchesi 1. introduzione la presenza di lembi di superfici pianeggianti sul versante occidentale della collina di torino era già stata osservata localmente in occasione di precedenti indagini geologiche (boano & forno, 1997; forno et al., 2002); studi successivi, riguardanti anche il versante nordoccidentale, avevano consentito di valutare in modo preliminare la diffusione di queste forme e di ricostruire la loro distribuzione secondo determinate fasce altimetriche: l’insieme degli elementi raccolti aveva permesso di interpretarli come i relitti di più estese superfici pianeggianti costituenti una successione fluviale terrazzata riferibile al pleistocene medio e superiore, indicativa di una sensibile deformazione recente dell’area collinare (boano et al., 2002; boano et al., 2004). il presente lavoro sintetizza i risultati ottenuti dallo studio sistematico di questa successione, effettuato attraverso un rilevamento geologico di dettaglio alla scala 1:10.000 dei versanti occidentale e nordoccidentale della collina di torino. in particolare si è realizzata una carta geologica (tav. 1) in cui sono rappresentate le singole forme di modellamento fluviale, erosionali e deposizionali, che hanno consentito di effettuare una ricostruzione complessiva della successione terrazzata. il lavoro effettuato è risultato difficoltoso per la ridotta estensione dei lembi, per la generalizzata scarsità di affioramenti e per la presenza di una diffusa copertura di loess eolico e di prodotti colluviali. e’ stato inoltre condizionato dall’intensa antropizzazione dell’area, iniziata già nel 1700, che determina condizioni particolari per quanto riguarda l’acquisizione dei dati geologici: da un lato i frequenti scavi per la realizzazione di edifici offrono l’occasione di osservare periodicamente i sedimenti e di integrare le indagini sul terreno con le prove geotecniche o le perizie geologiche esistenti; da un altro lato, essendo l’area in esame adibita in larga misura ad uso residenziale, la raccolta dei dati è notevolmente ostacolata dalle difficoltà di accesso alle proprietà (fig. 1). l’acquisizione dei dati è inoltre talvolta impedita da interventi antropici di diversa entità, che determinano una modesta densità di affioramento e creano alcune difficoltà nel ricostruire la morfologia originaria dei lembi di superfici terrazzate: spesso i sedimenti appaiono mascherati da muri e pavimentazioni; talvolta si hanno modifiche morfologiche, quali ad esempio l’ampliamento degli originari settori pianeggianti tramite riporti sorretti da muri e interventi di spianamento, o avviene la dissezione delle originarie forme terrazzate per la realizzazione di nuovi accessi alle proprietà. solo molto localmente gli interventi determinano invece la creazione di settori pianeggianti totalmente artificiali che, ad un’analisi più dettagliata, appaiono chiaramente non correlabili ai lembi naturali sia per una anomala distribuzione plano-altimetrica sia per le dimensioni, generalmente più ridotte. 2. lavori precedenti la successione di sedimenti marini terrigeni costituenti il rilievo collinare, di età compresa tra l’eocene e il pliocene, è stata oggetto di numerosi lavori a carattere generale tra cui ricordiamo la seconda edizione del foglio geologico “torino” alla scala 1:100.000 (bortolami et al., 1969), le relative note illustrative (bonsignore et al., 1969) e alcuni approfondimenti successivi (sturani, 1975). le ricerche svolte negli ultimi anni hanno riguardato essenzialmente la ricostruzione degli eventi deformativi che interessano la successione marina: la struttura collinare è stata interpretata come una antiforme separata dall’antistante pianura padana tramite un insieme di importanti elementi tettonici sepolti, indicati complessivamente come "thrust padano" (consiglio nazionale delle ricerche, 1990; piana & polino, 1994) (cfr. inserto 1 di tav. 1). per quanto riguarda i sedimenti quaternari dell’area collinare nella cartografia ufficiale (bortolami et al., 1969) sono stati indicati esclusivamente i principali fig. 1 in corrispondenza a numerosi lembi di superfici terrazzate sono stati costruiti antichi edifici residenziali: nell’immagine è osservabile il lembo di villa prever (attuale villa abeg) (q. 292) riferibile all’unità di monte dei cappuccini (2 in tav. 1). some ancient villas have been built in various terraced surfaces: in the picture it can be seen the surface of villa prever (present villa abeg) at 292 m, related to the monte dei cappuccini unit (2 in tav. 1). fig. 2 il profilo geologico in corrispondenza al lembo di villa gualino (unità 4 in tav. 1) evidenzia un corpo sedimentario fluviale sviluppato in discordanza al di sopra del substrato marino e coperto dal loess eolico. 1) substrato marino; 2) depositi fluviali; 3) depositi colluviali; 4) loess eolico; 5) terreno di riporto (modificato da boano et al., 2004). the geological section of the villa gualino terraced surface (unit 4 in tav. 1) shows a fluvial sedimentary body in unconformity on the marine bedrock and covered by the aeolian loess. 1) marine bedrock; 2) fluvial sediments; 3) colluvial sediments; 4) aeolian loess; 5) dum (modified from boano et al., 2004). 5 4 3 2 1 lembi della copertura di loess e non compariva invece la successione fluviale oggetto del presente studio; i sedimenti eolici dell’area collinare, riferibili al pleistocene superiore, sono stati in seguito oggetto di indagini specifiche, che hanno consentito di differenziarli dagli altri termini e di precisarne la distribuzione e lo spessore (forno, 1979; 1990). il primo elemento significativo per la ricostruzione dell’evoluzione quaternaria dell’area in esame è stata l’ipotesi di c a r r a r o (1976) secondo la quale il settore di pianura sviluppato immediatamente a nw della collina di torino sarebbe stato modellato dagli attuali affluenti del f. po e non dal corso d’acqua principale, impostato in questo settore in epoca estremamente recente: la conferma di questa ipotesi è avvenuta negli anni successivi attraverso il riconoscimento della presenza, in corrispondenza al versante meridionale della collina di torino e all’adiacente altopiano di poirino, di sedimenti fluviali associati a relitti di meandri incastrati riferibili al pleistocene medio e superiore, indicativi del deflusso del precedente collettore principale a sud della collina di torino (forno, 1980; forno, 1982; carraro et al., 1982). in seguito gli studi riguardanti l’evoluzione pliopleistocenica dell’area piemontese hanno evidenziato come la collina di torino e l’area di pianura sviluppata immediatamente a nw del rilievo siano stati e siano tuttora interessati da un comportamento geodinamico differente, corrispondente rispettivamente ad un sensibile sollevamento e ad una relativa stabilità (carraro et al., 1987): le stesse ricerche hanno considerato questa evoluzione differenziale la principale responsabile delle profonde modificazioni nell’assetto del reticolato idrografico dell’area piemontese durante il pleistocene. studi specifici sulla composizione dei clasti costituenti i depositi fluviali connessi con il collettore sviluppato sul versante meridionale della collina di torino suggeriscono l’alimentazione da parte del settore alpino occidentale, compreso tra la val sangone e le valli di lanzo (compagnoni & forno, 1992) (cfr. inserto 2 di tav. 1). solo recentemente è stata effettuata una cartografia preliminare della successione di forme fluviali terrazzate pleistoceniche conservate sul versante occidentale del rilievo collinare: tali indagini hanno consentito una prima ricostruzione, essenzialmente su base morfologica, dell’antico reticolato idrografico e un riferimento, su base pedostratigrafica, al pleistocene medio e superiore (boano & forno, 1997). in corrispondenza ad una di queste forme, e in particolare al lembo di villa gualino, caratterizzato da notevole estensione, lo studio di un insieme di sondaggi a carotaggio continuo ha consentito di individuare la presenza nell’immediato sottosuolo di un corpo lenticolare di depositi fluviali 125la successione fluviale pleistocenica ... sabbioso-siltosi, con spessore di circa 5 metri, che poggia in discordanza sui termini marini ed è coperto dal loess eolico (forno et al., 2002) (fig. 2). un quadro più completo dell’evoluzione del reticolato idrografico pleistocenico del piemonte centrale è contenuto in c a r r a r o et al . (1994): successivi approfondimenti riguardanti la collina di torino ne hanno precisato l’intensa evoluzione tettonica recente (boano et al., 2000; boano et al., 2002; boano et al., 2004). 3. assetto morfologico la collina di torino costituisce un rilievo che supera i 700 m di quota e si eleva di circa 500 rispetto fig. 3 modello digitale del terreno del piemonte centrale: la collina di torino, incisa al margine settentrionale dall’attuale f. po, forma un rilievo che si innalza di circa 500 m sulla pianura, costituita dagli estesi conoidi dei corsi d’acqua alpini (modificato da arpa piemonte, sigeoonline, 2004). terrestrial digital model of the central piedmont: the collina di torino develops a relief that is cut at the northern margin by the river po and that rises from the plain formed by the wide alpine fluvial aprons of about 500 metres (modified from arpa piemonte, sigeoonline, 2004). fig. 4 vista da nw degli estesi lembi di superfici terrazzate del versante nordoccidentale della collina di torino, sospesi di alcune centinaia di metri rispetto al tratto di pianura padana su cui sorge la città di torino. nw sight of the wide terraced surfaces of the northwestern slope of the collina di torino. they are suspended some hundreds of metres respect to the sector of po plain where the town of torino is built. 126 alla contigua pianura padana occidentale, dalla quale è separato tramite l’incisione del f. po (fig. 3). l’area in esame corrisponde, in particolare, ai versanti occidentale e nordoccidentale del rilievo collinare delimitati, rispetto al versante meridionale, dallo spartiacque principale con direzione circa sw-ne. entrambi i versanti presentano un insieme di ampie dorsali allungate, caratterizzate da andamento rispettivamente e-w e senw, separate tra loro da incisioni relativamente strette modellate dall’attuale reticolato idrografico affluente del f. po, con profondità compresa tra alcune decine e il centinaio di metri: a partire da sw si sviluppano in particolare le dorsali di moncalieri, boccia d’oro, ronchi, cavoretto, tetti rovei, san vito, santa margherita, villa rey, reaglie, mongreno, superga e costa parigi (tav. 1). la caratteristica morfologica più evidente delle dorsali collinari è rappresentata dal loro profilo longitudinale articolato: la regolarità nell’inclinazione delle dorsali è interrotta da numerosi lembi di superfici pianeggianti o debolmente inclinate (fig. 4) e, localmente, da ampie depressioni allungate, in contropendenza. i lembi pianeggianti hanno estensione relativamente ridotta, compresa tra 5.000 e 25.000 m2, e allungamento per lo più indipendente dall’andamento dell’attuale reticolato idrografico collinare. in generale presentano una modesta inclinazione, in media del 3% verso w o nw, secondo l’allungamento delle dorsali: nel dettaglio i lembi sviluppati a quote maggiori mostrano complessivamente inclinazioni più sensibili e ondulazioni più marcate (cfr. inserto 6 in tav. 1); i lembi a quote inferiori appaiono invece meno inclinati e sono caratterizzati da un andamento relativamente pianeggiante (fig. 1). le depressioni allungate, caratterizzate da un settore centrale depresso di qualche metro rispetto alle aree laterali, hanno distribuzione planimetrica localizzata nella fascia altimetrica superiore del versante occidentale: mostrano un evidente andamento arcuato in pianta e ampiezza relativamente estesa, fino a diverse migliaia di m2 (cfr. inserto 4 in tav. 1). l’insieme dei dati in seguito esposti consente di interpretare questi elementi morfologici come i relitti di antiche forme fluviali costituenti una successione terrazzata (fig. 4): in particolare i lembi pianeggianti rappresentano settori conservati, marginali, di precedenti pianure alluvionali e le depressioni in contropendenza corrispondono a relitti di antichi meandri incastrati. dal punto di vista altimetrico la successione terrazzata è distribuita in corrispondenza a gran parte dello sviluppo delle dorsali, tra 630 e 240 m di quota (tav. 1). i singoli lembi mostrano una distribuzione altimetrica concentrata in determinate fasce altimetriche: possono essere raggruppati in undici ordini di forme terrazzate conservati per il versante occidentale e quattordici per quello nordoccidentale; nel dettaglio le singole dorsali non mostrano in genere testimonianza dell’intera successione, ma preservano un numero minore di ordini (cfr. inserto 7 in tav. 1). in generale si osserva che le forme fluviali a quote superiori sono conservate in modo discontinuo e appaiono più profondamente rimodellate e dissecate; i relitti a quote inferiori mostrano invece una distribuzione relativamente continua e appaiono generalmente più estesi e meglio conservati. le diverse forme terrazzate sono separate tra loro da scarpate con acclività compresa tra il 10 e 12 % e altezza di alcune decine di metri, relativamente costante per ogni singolo ordine. per quanto riguarda, invece, i caratteri planimetrici si osserva che le diverse forme sviluppate a quote confrontabili mostrano una distribuzione complessiva secondo fasce allungate in direzione s-n, sul versante occidentale, e sw-ne, su quello nordoccidentale (cfr. inserto 3 in tav. 1): è da sottolineare che questo andamento, circa parallelo allo spartiacque principale, è invece trasversale a quello degli attuali corsi d’acqua collinari. come precisato più avanti l’ampia distribuzione altimetrica complessiva della successione, generalizzata a gran parte del rilievo collinare, suggerisce che i fenomeni di modellamento fluviale siano avvenuti a spese di un rilievo interessato da una sensibile deformazione recente (boano et al., 2004). le ondulazioni e le ridotte dimensioni delle forme conservate sono invece indicative del rimodellamento da parte del ruscellamento diffuso e della dissezione da parte del reticolato idrografico attuale, caratterizzato da notevoli gradienti e impostato in sedimenti facilmente erodibili. come descritto dettagliatamente in seguito, l’allungamento complessivo s-n e sw-ne di queste forme suggerisce il legame delle originarie forme fluviali con un precedente reticolato idrografico, circa parallelo allo spartiacque principale (cfr. inserto 3 in tav. 1), progressivamente coinvolto nella deformazione dell’edificio collinare e dissecato dagli attuali corsi d’acqua. la presenza di questa successione favorisce la spiccata vocazione residenziale dell’area in esame, compresa in gran parte nel comune di torino: in particolare sui lembi terrazzati sono costruite le antiche ville che caratterizzano l’area collinare (fig. 1); le incisioni fluviali, corrispondenti ai tratti più ripidi dei versanti caratterizzati da diffusi fenomeni di dissesto, sono invece per lo più incolti e presentano una fitta vegetazione arbustiva. 4. la successione fluviale terrazzata la successione fluviale terrazzata conservata sui versanti occidentale e nordoccidentale della collina di torino è costituita da numerose forme relitte distribuite in modo piuttosto uniforme e secondo fasce allungate parallelamente all’attuale spartiacque collinare. solo in corrispondenza al settore di valsalice, compreso tra le dorsali di san vito a sw e di santa margherita a ne, non sono conservate forme di modellamento fluviale riconducibili a quelle presenti nel resto del rilievo (tav. 1). in generale si è osservato che le forme sviluppate a quote inferiori preservano in modo relativamente continuo gli originari sedimenti fluviali: questi sono interessati da suoli meno evoluti, con indice di colore compreso tra 7.5 yr e 10 yr (munsell soil color charts). i lembi a quota superiore conservano invece solo in modo sporadico gli originari depositi fluviali: su questi depositi, o direttamente sui termini marini, si sviluppano suoli profondamente evoluti, con indice di colore compreso tra 2.5 yr e 5 yr (munsell soil color charts). in corrispondenza alla maggior parte dei lembi g. forno & s. lucchesi 127 pianeggianti terrazzati sono conservati depositi prevalentemente fini (fig 5): le analisi granulometriche effettuate indicano che i diversi campioni (curve a, b, c, d, e, f, j in fig. 6) corrispondono a sabbie-limose debolmente argillose e mostrano una composizione tessiturale tra loro piuttosto simile; in particolare si osserva una prevalenza dei granuli con dimensioni comprese tra 1 e 0.01 mm: tale composizione tessiturale, indicativa di una scarsa selezione dei depositi e caratterizzata dalla presenza di “code” sia ghiaiose sia argillose, è in accordo con l’origine fluviale dei sedimenti in esame (rizzetto et al., 1998); è inoltre evidente la loro differenziazione rispetto al loess eolico presente localmente al di sopra dei sedimenti fluviali (fig. 6), con il quale macroscopicamente possono essere confusi, contraddistinto invece da una maggiore selezione tessiturale (forno, 1979). in corrispondenza ai relitti di meandri incastrati sono invece conservati sedimenti con tessitura ghiaioso-sabbiosa più eterogenea (curva i in fig. 6). la successione fluviale terrazzata è stata differenziata utilizzando il criterio allostratigrafico, attraverso il riconoscimento delle discontinuità erosionali che definiscono la base e il tetto delle singole unità: le superfici sommitali delle unità sono direttamente rilevabili sul terreno; le loro superfici di appoggio basale, invece, sono osservabili solo localmente e talvolta identificabili tramite dati di sottosuolo. in generale le diverse unità sono state definite sulla base di un insieme di caratteri: 1) distribuzione altimetrica delle forme terrazzate che, anche se conservate in tutto lo sviluppo dei versanti, mostrano una distribuzione preferenziale secondo determinate fasce altimetriche; 2 continuità laterale delle forme terrazzate, che risultano dissecate dalle attuali incisioni; 3) analoga entità del rimodellamento e della dissezione che interessano le forme terrazzate; 4) estensione confrontabile delle forme terrazzate; 5) analoga morfologia delle forme, corrispondenti a superfici pianeggianti o a relitti di meandri incastrati; 6) analoghi facies e grado di conservazione dei depositi fluviali; 7) grado di evoluzione dei suoli confrontabile. complessivamente la successione terrazzata mostra un assetto altimetrico connesso con la deformazione recente (boano et al., 2004): i diversi lembi in origine erano distribuiti a quota sensibilmente inferiore, corrispondente allo sviluppo altimetrico della originaria pianura. l’insieme dei dati raccolti suggerisce però che tale deformazione sia confrontabile per i diversi lembi appartenenti ad una determinata fascia altimetrica e non alteri i rapporti tra le diverse fasce, che risultano separate tra loro da scarpate con altezza di alcune decine di metri (cfr. inserto 7 in tav. 1). si osserva inoltre come, anche nel dettaglio, lo sviluppo altimetrico dei singoli lembi terrazzati possa variamente discostarsi da quello originario, corrispondendo a forme relativamente antiche interessate da un più o meno intenso rimodellamento ad opera del ruscellamento diffuso e/o dal seppellimento da parte di una copertura eolica o colluviale: a seconda dei casi, si prospettano diverse relazioni tra la configurazione attuale e quella originaria. in particolare, valutando caso per caso la natura (1a, 1b, 1c, 1d, 2a, 2b, 2c, 2d in fig. 7) dei lembi attualmente conservati (t) è possibile ricondurli a due differenti tipologie originarie corrispondenti rispettivamente a lembi modellati nel substrato marino, già inizialmente privi di depositi fluviali (1), e a lembi caratterizzati dall’originaria presenza di sedimenti fluviali (2). nel primo caso, ossia a partire da un’originaria superficie di erosione impostata nel substrato (e), si possono formare lembi (t) con una quota leggermente inferiore (1a), a seguito del rimodellamento da parte del ruscellamento diffuso, lembi con uno sviluppo altimetrico confrontabile (1b e 1c), se interessati dallo stesso rimodellamento e da un successivo seppellimento ad opera di una copertura eolica e/o colluviale con spessore modesto, o infine lembi a quota leggermente più elevata (1d), a seguito unicamente del seppellimento ad opera della stessa copertura. nel secondo caso, ossia a partire da un’originaria superficie di accumulo dei sedimenti fluviali (a), si possono formare lembi (t) con uno sviluppo altimetrico leggermente inferiore impostati negli stessi sedimenti fluviali (2a), a seguito di un modesto rimodellamento da parte del ruscellamento diffuso, lembi con uno sviluppo altimetrico confrontabile se interessati dallo stesso rimodellamento e da un successivo seppellimento ad opera di una copertura eolica e/o colluviale di modesto spessore (2b e 2c), o infine lembi a quota leggermente più elevata, a seguito unicamente del seppellimento ad opera della stessa copertura (2d). infine, anche a partire da un’originaria configurazione di accumulo, si può verificare lo sviluppo di una superficie di erosione modellata a quota inferiore nel substrato marino (1a), a seguito della completa asportazione dei sedimenti fluviali. a commento della ricostruzione sopraesposta occorre precisare come non risulti sempre facile ricostruire l’evoluzione di un lembo terrazzato conservato nell’area collinare e definire quale fosse la situazione originaria. in generale si può affermare che, maggiore è il grado di rimodellamento e di dissezione delle forme, maggiore è la variazione rispetto alla configurazione originaria. nel dettaglio la presenza di prodotti colluviali a spese di depositi fluviali pedogenizzati, a valle di un determinato lembo terrazzato, indica l’esistenza di un’originaria copertura fluviale; al contrario lo sviluppo di suoli sul substrato marino suggerisce l’assenza, già in origine, dei depositi fluviali o il loro spessore estremamente ridotto. le configurazioni attuali più semplici da interpretare corrispondono ai lembi in cui è conservata l’originaria copertura fluviale, riconducibile alla situazione iniziale di accumulo (a). più difficili da valutare sono invece i lembi attualmente modellati nel substrato marino (1a), per i quali risulta spesso impossibile ricondurli ad un’originaria superficie di erosione (e) o ad una superficie di accumulo (a): in questi casi il riconoscimento della configurazione originaria può essere talvolta facilitato da altre evidenze. secondo il criterio allostratigrafico, l’elemento da utilizzare per correlare tra loro i diversi corpi sedimentari corrisponde alla superficie di erosione che ne segna la base: nel caso della successione terrazzata della collina di torino, considerando le limitazioni sopra la successione fluviale pleistocenica ... 128 accennate tra cui soprattutto la scarsità di affioramenti e le loro modeste dimensioni, che non consentono nella maggior parte dei casi di osservare la superficie basale dei depositi fluviali, si è dovuto ricorrere a considerare la quota della superficie attualmente visibile. quest’ultima, come sopra illustrato, può corrispondere sia ad una superficie di erosione modellata nel substrato marino (e) sia ad una superficie di accumulo dei depositi fluviali (a). in ogni caso la differenza di quota fra le due configurazioni è poco significativa in quanto sia lo spessore dei sedimenti fluviali sia l’entità del rimodellamento o dell’eventuale seppellimento, ad opera di sedimenti eolici o colluviali, comportano variazioni di alcuni metri e sono pertanto trascurabili se confrontati con le differenze altimetriche tra le diverse unità, corrispondenti alle scarpate che le separano, con altezza invece di alcune decine di metri (cfr. inserto 7 in tav. 1). nell’ambito di una stessa fascia altimetrica si determinano spesso condizioni di conservazione analoghe e quindi, a parità di quota, si confrontano di fatto elementi con lo stesso significato geologico. va inoltre precisato come, nei casi in cui uno stesso lembo risulti sviluppato a quota diversa da monte verso valle o in senso trasversale, viene sempre considerata, come riferimento, la quota più elevata in quanto rappresenta presumibilmente la situazione più conservativa (fig. 7). i dati raccolti a seguito del rilevamento geologico alla scala 1:10.000 sono sintetizzati nella carta geologica allegata (tav. 1): tenendo presente le possibili modificazioni antropiche precedentemente descritte, si è cercato di realizzare una cartografia dei soli lembi almeno in parte naturali, tralasciando ovviamente i lembi creati artificialmente. in particolare sono rappresentati tutti gli elementi morfologici e i depositi conservati sulle dorsali, facenti parte della successione fluviale terrazzata originaria: non sono invece cartografati gli elementi morfologici e i depositi conservati entro le incisioni fluviali attuali, connessi con il successivo modellamento da parte del reticolato affluente. i lembi che conservano i sedimenti fluviali sono rappresentati in modo differente da quelli privi di depositi: considerando la ridotta estensione dei lembi terrazzati, che rende la successione preservata di difficile lettura, si è anche effettuata una rappresentazione schematica della probabile distribuzione complessiva delle diverse unità costituenti la successione fluviale terrazzata, prima della dissezione da parte del reticolato idrografico affluente. tale rappresentazione è stata realizzata sulla base della distribuzione plano-altimetrica degli elementi conservati, integrata con quella dei prodotti colluviali che rielaborano gli originari sedimenti fluviali: comprende un insieme di “fasce” allungate parallelamente all’attuale spartiacque, indicate in colore più tenue rispetto alle relative aree di conservazione degli elementi morfologici e dei sedimenti. sono stati infine rappresentati i depositi fluviali conservati in pianura, che costituiscono il riferimento altimetrico della distribuzione originaria delle unità più recenti. le unità individuate sono state indicate con una numerazione progressiva, a partire da quelle conservate nelle fasce altimetriche inferiori: per quelle a quota più elevata, a causa della mancanza di correlabilità tra gli elementi dei due versanti, è stato necessario effettuare un’ulteriore differenziazione delle unità, introducendo il riferimento “w” per il versante occidentale e “n” per quello nordoccidentale (cfr. inserti 5 e 7 in tav. 1). i principali caratteri relativi ad ogni singola unità vengono di seguito brevemente descritti a partire da quelle a quota inferiore. 1 l’unità di madonna del pilone comprende cinque lembi terrazzati sviluppati ad una quota compresa tra 258 e 240 m, con distribuzione estremamente discontinua in entrambi i versanti, e una sella in contropendenza immediatamente a e del monte dei cappuccini (fig. 10). i lembi, che conservano una superficie subpianeggiante prossima a quella originaria, mostrano estensione generalmente ridotta di poche centinaia di m2: l’unico lembo di dimensioni rilevanti, con estensione di circa 4.000 m2, è quello più settentrionale (v. savio) sede dell’istituto piante da legno “ipla” (stop 2.11 in carraro et al, 2005). in corrispondenza ai diversi lembi sono stati osservati sedimenti fluviali sabbioso-siltosi scarsamente addensati, con spessore variabile tra 3 e 4 m, molto debolmente alterati e g. forno & s. lucchesi fig. 5 aspetto dei depositi fluviali siltoso-sabbiosi affioranti in corrispondenza al lembo di superficie terrazzata di villa prever (attuale v. abeg, q. 292, unità 2). aspect of the silt-sandy fluvial deposits outcropping in the terraced surface of villa prever (292 m, unit 2). fig. 6 curve granulometriche cumulative dei sedimenti presi in esame, confrontate con la curva del loess eolico affiorante a villa gualino: (a) scuola di s. margherita; (b) ne di tetti rovei; (c) cavoretto; (d) il bellardo; (e) villa s. croce; (f) villa sambuelli; (g) villa rey; (h) e di residenza superga ; (i) torre; (j) boccia d’oro. granulometric cumulative curves of the examined sediments, compared with the curve of the aeolian loess outcropping at villa gualino: (a) scuola of s. margherita; (b) ne of tetti rovei; (c) cavoretto; (d) il bellardo; (e) villa s. croce; (f) villa sambuelli; (g) villa rey; (h) e of residenza superga ; (i) torre; (j) boccia d’oro. caratterizzati da suoli bruno-giallastri con indice di colore 10 yr 4/4÷5/3 ( munsell soil color charts): solo in corrispondenza al lembo su cui è costruito parte del centro storico di moncalieri, sulla dorsale omonima, non si sono potute effettuare osservazioni sulla costituzione dei sedimenti. nel lembo di v. savio, al di sotto dei sedimenti siltosi, sono stati rinvenuti in affioramento e individuati nei sondaggi, per uno spessore di alcuni metri, sedimenti fluviali ghiaiosi, caratterizzati da ciottoli prevalentemente allungati con dimensioni comprese tra alcuni cm e alcuni dm, costituiti da serpentiniti, prasiniti, quarziti e gneiss; nel lembo della chiesa di sassi, al di sotto dei sedimenti siltosi, sono stati rinvenuti sedimenti fluviali sabbiosi, con spessore visibile di circa 2 m. 2 l’unità del monte dei cappuccini è rappresentata da diciannove lembi terrazzati sviluppati tra 300 e 280 m, conservati con notevole continuità laterale su entrambi i versanti. i lembi, anch’essi caratterizzati da una superficie subpianeggiante prossima a quella originaria, hanno estensione media di alcune centinaia di m2 (fig. 1) e allungamento preferenziale in direzione s-n nel versante occidentale e circa sw-ne in quello nordoccidentale: nella quasi totalità dei casi conservano depositi fluviali sabbioso-siltosi scarsamente addensati, con spessore medio di circa 2 m, molto debolmente alterati e caratterizzati da suoli bruno-giallastri con indice di colore compreso tra 10 yr 4/4 e 10 yr 5/4 (fig. 5); localmente i sedimenti presentano pseudogley di colore grigio 2,5 y 5/4. particolarmente significativi risultano i lembi del monte dei cappuccini (fig. 8) e del convitto principessa felicita di savoia, in corrispondenza ai quali è osservabile uno spessore di circa 2 m di depositi fluviali sabbiosi con colore bruno-giallastro 10 yr 4/4. 3 l’unità di villa rey comprende nove lembi terrazzati conservati tra 320 e 310 m, aventi dimensioni piuttosto ridotte, forma irregolare e superficie debolmente ondulata; la distribuzione areale dei lembi è disomogenea in quanto appaiono in gran parte concentrati sul versante nordoccidentale. nella quasi totalità dei casi conservano depositi fluviali siltoso-sabbiosi, con spessore visibile compreso tra 2 e 3 m, debolmente alterati e caratterizzati da suoli con indice di colore variabile tra bruno-giallastro 10 yr 4/3 e bruno 7.5 yr 4/6 e da una modesta cementazione carbonatica. in alcuni affioramenti, in particolare presso villa rey sulla dorsale omonima, al di sopra dei sedimenti fluviali è osservabile una copertura con spessore variabile tra 2 e 4 m di loess eolico, caratterizzato da una note129 fig. 7 diverse configurazioni (t) degli attuali lembi di superfici terrazzate (1a, 1b, 1c, 1d, 2a, 2b, 2c, 2d) a partire dalle due possibili tipologie iniziali (1 e 2), a seguito di fenomeni di rimodellamento e/o seppellimento. different configuration (t) of the present terraced surfaces (1a, 1b, 1c, 1d, 2a, 2b, 2c, 2d) from two possible initial conditions (1 and 2) as a consequence of remodelling and/or burial phenomena. la successione fluviale pleistocenica ... vole coesione e da una evidente fessurazione prismatica (forno, 1979; 1990); la lisciviazione di questi depositi è responsabile della locale cementazione dei depositi fluviali e della formazione di un livello di caliche, con spessore di alcuni centimetri, a sottolineare il limite tra i due sedimenti. 4 l’unità di villa gualino comprende sedici lembi terrazzati conservati tra 345 e 320 m, con notevole continuità laterale: i lembi mostrano estensione media di alcune centinaia di m2 e allungamento variabile; presentano una superficie ondulata, indicativa di un sensibile rimodellamento. nella quasi totalità dei casi conservano gli originari depositi fluviali siltososabbiosi, con spessore conservato compreso tra 2 e 5 metri, mediamente alterati e caratterizzati da suoli con indice di colore bruno 7.5 yr 4/4; su alcuni lembi, al di sopra dei sedimenti fluviali, si sviluppa una copertura di loess eolico con spessore metrico. particolarmente esteso risulta il lembo di villa gualino sulla dorsale di s. vito, compreso in questa unità e già oggetto di uno studio specifico (forno et al., 2002) (fig. 2): la realizzazione di numerosi sondaggi ha consentito di precisare la geometria lenticolare dei sedimenti fluviali in cui è modellato, con spessore di circa 5 m, costituiti da un termine inferiore sabbioso e da un termine superiore essenzialmente siltoso; al di sopra dei sedimenti fluviali si sviluppa il loess eolico, carbonatico, con spessore metrico. particolarmente significativo è anche il lembo sviluppato a sw dell’abitato di cavoretto, sulla dorsale omonima: conserva diffusamente depositi fluviali siltosi, osservabili per uno spessore di circa 3 m e coperti dal loess eolico, con spessore di circa 2.5 m; i depositi fluviali sono caratterizzati nella parte inferiore da concentrazioni di noduli di mn con diametro millimetrico. 5 l’unità di cavoretto è rappresentata anch’essa da sedici lembi terrazzati conservati su entrambi i versanti tra 370 e 340 m e caratterizzati da una superficie ondulata, indicativa di un sensibile rimodellamento. nel versante occidentale i lembi mostrano una buona continuità laterale, dimensioni compresa tra 50 e 300 m2 e allungamento prevalente s-n; nel versante nordoccidentale i lembi risultano invece sensibilmente dissecati, mostrano dimensioni molto più ridotte e allungamento variabile. la continuità laterale di questa unità sembra essere interrotta nel settore di valsalice, compreso tra le dorsali di san vito e santa margherita, al raccordo tra i due versanti. nella maggior parte dei casi, soprattutto sul versante occidentale, conservano gli originari depositi fluviali siltososabbiosi, con spessore conservato fino a 3 m e appaiono mediamente alterati, con indice di colore bruno 7.5 yr 4/4. particolarmente significativo è il lembo di tetti rovei, sulla dorsale omonima, caratterizzato da un corpo fluviale lenticolare con spessore di circa 2,5 m: la superficie di appoggio dei sedimenti fluviali, con andamento concavo, appare sottolineata da un orizzonte carbonatico di spessore centimetrico. 6n l’unità del bellardo è rappresentata da sette lembi terrazzati conservati esclusivamente nel versante nordoccidentale, tra 380 e 370 m, e caratterizzati da una superficie ondulata, indicativa di un sensibile rimodellamento. i lembi mostrano estensione generalmente ridotta di poche decine di m, e allungamento prevalentemente in direzione se-nw. solo alcuni lembi conservano gli originari depositi fluviali, generalmente siltoso-sabbiosi o siltoso-argillosi, con indice di colore 7.5 yr 4/6: particolarmente significativo è il lembo del bellardo sulla dorsale di realie, allungato in direzione n-s; in corrispondenza a questo lembo si osservano sedimenti fluviali siltososabbiosi con spessore visibile di circa 2 m. 7n l’unità del fortino è rappresentata da otto lembi terrazzati, ondulati nel dettaglio, conservati esclusivamente in corrispondenza al versante nordoccidentale tra 390 e 385 m. i singoli lembi hanno estensione generalmente inferiore a 100 m2, allungamento variabile da e-w a se-nw e conservano solo localmente gli originari depositi fluviali, caratterizzati da tessitura siltoso-sabbiosa o siltoso-argillosa e indice di colore medio 5 yr 4/6. la maggior parte dei lembi risultano invece modellati direttamente sul substrato terziario, interessato da un suolo con grado di evoluzione confrontabile a quello dei sedimenti fluviali localmente preservati, come ad esempio in corrispondenza al lembo di villa corra. particolarmente significativi sono i lembi del fortino, sulla dorsale di santa margherita, e di villa maggia, sulla dorsale di reaglie; in entrambi i casi i lembi non risultano compresi nella fascia di interpolazione dell’unità 7n ma sono inglobati in quelli della successiva unità 6n, rispetto alla quale appaiono sospesi; in corrispondenza a entrambi si osservano localmente sedimenti fluviali siltoso-sabbiosi, costituenti corpi lenticolari con spessore rispettivamente di circa 2,5 e 5 m, separati dal substrato sottostante da superfici di erosione con andamento concavo. 8w e 8n le unità di san vito e di villa sambuelli comprendono rispettivamente nove e dodici lembi conservati sui versanti occidentale, tra 415 e 410 m, e nordoccidentale, tra 420 e 400 m. le due unità mostrano caratteri morfologici e sedimentologici confrontabili: sono state tuttavia tra loro differenziate, in quanto non vi è continuità laterale tra i lembi sviluppati nei due versanti; i lembi del versante occidentale si raccordano con i relitti di meandri incastrati conservati nel versante meridionale a quota leggermente inferiore. i lembi di entrambi i versanti hanno superficie debolmente ondulata e risultano piuttosto articolati in pianta; hanno estensione di alcune centinaia di m2, mediamente superiore rispetto alle altre unità, e allungamento variabile. generalmente conservano, in particolare per l’unità di san vito, gli originari depositi fluviali siltosi, con spessore visibile di 2-3 m e indice di colore medio 5 yr 5/6; negli altri casi risultano invece modellati direttamente sul substrato terziario, su cui si sviluppa un suolo con grado di evoluzione confrontabile a quello dei sedimenti fluviali localmente preservati. particolarmente significativi sono i lembi di villa racca, sulla dorsale di boccia d’oro, e di villa maria, sulla dorsale di villa rey, entrambi allungati in direzione e-w; in corrispondenza a questi lembi, al di sotto di una copertura di loess ricco di gasteropodi continentali, con spessore di circa 3 m, si osservano per uno spessore di 2 m sedimenti fluviali siltoso-argillosi, caratterizzati da una colorazione bruno-rossastra 5 yr 4/4, dalla presenza di patine di argilla e da una notevole cementazione da parte degli ossidi di fe, indicative di una sensibile alterazione pedogenetica. in corrispondenza al lembo di v. cavoretto, sulla dorsale di boccia d’oro, sono invece osservabili sedimenti fluviali ghiaiosi con spessore visibile di circa 2 m: i ciottoli, con diametro variabile tra alcuni centimetri e circa 10 cm, sono costituiti prevalentemente da serpentiniti e anfiboliti con subordinati prasiniti, gabbri e micascisti; al di sopra di questi depositi si sviluppa una copertura di loess con spessore di circa 4 m, ricco di concrezioni carbonatiche allungate verticalmente. anche in corrispondenza al lembo di villa sambuelli, sulla dorsale di regalie, si osservano sedimenti fluviali sabbiosoghiaiosi, con spessore di alcuni metri: i ciottoli, con diametro da centimetrico a decimetrico, sono costituiti da serpentiniti, gabbri, peridotiti, prasiniti, gneiss e calcari. localmente al margine dei lembi sono presenti prodotti colluviali, legati alla rielaborazione degli originari sedimenti fluviali da parte del ruscellamento diffuso, come ad esempio nei lembi di villa paradiso, villa maria, villa sambuelli, la fagianella, villa ada e villa lena. 9w e 9n – le unità dei ronchi e di villa tabasso comprendono rispettivamente cinque e dieci lembi conservati sui versanti occidentale, tra 445 e 430 m, e nordoccidentale, tra 445 e 425 m (cfr. inserto 6 in tav. 1). anche in questo caso le due unità, pur mostrando caratteri morfologici e sedimentologici confrontabili, sono state tra loro differenziate in quanto non vi è continuità laterale tra i lembi sviluppati nei due versanti; i lembi del versante occidentale si raccordano con i relitti di meandri incastrati conservati nel versante meridionale a quota leggermente inferiore. i lembi di entrambi i versanti sono caratterizzati da forma allungata, in direzione compresa tra e-w e se-nw, e da una superficie ondulata indicativa di un sensibile rimodellamento; risultano piuttosto articolati in pianta e hanno estensione di alcune centinaia di m2. solo i lembi sviluppati nel versante occidentale e il lembo di villa tabasso, nel versante nordoccidentale, conservano i depositi fluviali, con spessore visibile compreso tra 2 e 4 m e colore bruno-rossastro variabile tra 5 yr 4/2÷5/3. particolarmente significativi sono i lembi di villa bobella, nella dorsale di boccia d’oro , e di villa tabasso, nella dorsale di reaglie: al di sopra del substrato marino si sviluppano depositi fluviali siltoso-argillosi relativamente omogenei con uno spessore di circa 4 m, caratterizzati da una colorazione bruno-rossastra 5 yr 5/4. 10w l’unità di c. feno comprende tre lembi molto allungati e con larghezza ridotta sviluppati sul versante occidentale tra 490 e 485 m: sono caratterizzati da allungamento prevalente e-w e andamento ondulato, indicativo di un sensi130 g. forno & s. lucchesi bile rimodellamento. queste forme si raccordano con relitti di meandri osservabili nel versante meridionale, a quota leggermente inferiore. conservano gli originari depositi fluviali siltoso-argillosi caratterizzati da un colore bruno-giallastro 5 yr 4/6; solo in corrispondenza al lembo di c. feno, sulla dorsale di cavoretto, si osservano ridotti affioramenti di sedimenti ghiaiosi. 11w l’unità di torre comprende due relitti di meandri incastrati sviluppati esclusivamente sul versante occidentale tra 510 e 495 m, con forma irregolare in pianta ed estensione di alcune migliaia di m2: queste forme si raccordano con analoghi relitti conservati nel versante meridionale a quota leggermente inferiore. tali relitti si differenziano sensibilmente dai lembi pianeggianti delle altre unità, oltre che per le maggiori dimensioni, per il profilo trasversale concavo, caratterizzato da una evidente depressione centrale, e per la forma arcuata in pianta (cfr. inserto 4 in tav. 1): conservano diffusamente sedimenti siltoso-argillosi con indice di colore 5 yr 4/6 e spessore variabile tra 2 e 5 m. particolarmente significativo è il lembo su cui si sviluppa cascina long (stop 2.9 in carraro et al, 2005), dove i sedimenti fluviali siltosi, con spessore fino a circa 5 m, coprono una evidente superficie d’erosione concava modellata sul substrato marino. nel relitto di torre (stop 2.10 in carraro et al, 2005), alla base dei sedimenti siltosi, si osservano corpi lenticolari di sedimenti fluviali sabbioso-ghiaiosi, con spessore di alcuni metri: i ciottoli, con diametro da centimetrico a decimetrico, sono costituiti da serpentiniti, prasiniti, anfiboliti, gabbri, peridotiti, quarziti e calcari; i depositi ghiaiosi contengono numerose concrezioni carbonatiche subsferiche con diametro centimetrico. 12n, 13n e 14n le unità di villa morano, di bric delle ghiaie e dell’eremo comprendono un numero ridotto di lembi conservati esclusivamente sul versante nordoccidentale rispettivamente tra 500 e 490 m, tra 540 e 520 e tra 630 e 600. i lembi, con estensione modesta di poche decine di m2, appaiono sensibilmente rimodellati e dissecati, con la conseguenza che risultano più difficoltose e incerte la loro correlazione e attribuzione alle diverse unità: in particolare i lembi riferibili all’unità 12n appaiono molto allungati e con larghezza ridotta. i diversi lembi, risultano modellati nei sedimenti marini del substrato, su cui in genere si sviluppa un suolo con spessore visibile di alcuni metri e indice di colore medio 2.5 yr 4/4÷4/6. infine, nella fascia altimetrica superiore del versante, lungo lo spartiacque principale, sono riconoscibili settori subpianeggianti, sviluppati tra il colle della maddalena (q. 715) e la basilica di superga (q. 669) (fig. 4). a causa della sensibile ondulazione, della ridotta estensione e dell’assenza di sedimenti fluviali non è possibile ricostruire l’originaria morfologia di questi settori e pertanto chiarire se siano interpretabili come lembi di superfici terrazzate, intensamente rimodellati e dissecati, o semplicemente come rilievi; nel settore della basilica di superga sono inoltre documentati estesi interventi antropici che hanno sensibilmente modificato la morfologia originaria: per tali motivi queste forme non sono state inserite in alcuna unità e differenziate solo dove conservano relitti di suoli e/o prodotti colluviali molto evoluti. 5. considerazioni conclusive lo studio sistematico dei versanti occidentale e nordoccidentale del rilievo collinare, effettuato attraverso la cartografia e l’analisi dettagliata delle forme e dei depositi quaternari, conferma la diffusa conservazione di relitti di modellamento fluviale (fig. 4): si osservano in particolare numerosi lembi di superfici pianeggianti (cfr. inserto 6 in tav. 1) in corrispondenza alla maggior parte dei quali sono conservati sedimenti fluviali sabbioso-siltosi (fig. 5); solo localmente, nella fascia altimetrica superiore del versante occidentale, sono presenti alcuni relitti di meandri incastrati (cfr. inserto 4 in tav. 1), a cui sono associati sedimenti ghiaiosi. la distribuzione di queste evidenze su diverse fasce altimetriche ne consente l’interpretazione come una successione fluviale terrazzata costituita da diverse unità informali, definite con criteri allostratigrafici (cfr. inserti 5 e 7 in tav. 1). come già indicato in precedenti contributi la successione è attualmente conservata in corrispondenza al settore collinare a seguito di una sensibile deformazione sinmorfogenetica (boano et al., 2004). per individuare i diversi termini costituenti la successione presa in esame sono state effettuate correlazioni utilizzando la continuità laterale degli elementi morfologici, la loro distribuzione altimetrica e i caratteri tessiturali e pedogenetici dei sedimenti fluviali localmente presenti; questi elementi sono stati integrati con un insieme di evidenze riguardanti le aree limitrofe. la risposta coerente fornita dai diversi tipi di osservazioni suggerisce come, nel caso specifico, la deformazione, sia confrontabile a parità di fascia altimetrica e non alteri i rapporti geometrici tre le diverse fasce. sono state così individuate nove unità informali nel versante occidentale e dodici nel versante nordoccidentale (cfr. inserti 5 e 7 in tav. 1): in particolare nelle fasce altimetriche più elevate le forme appaiono più rimodellate e conservano depositi con maggior grado di alterazione; nelle fasce altimetriche inferiori le forme risultano invece meno rimodellate e i depositi sensibilmente meno alterati. lo studio pedostratigrafico dei sedimenti fluviali associati alle forme descritte, calibrato su scala pedostratigrafica locale (arduino et al., 1984), consente di collocare cronologicamente l’intera successione terrazzata tra la parte inferiore del pleistocene medio e la fine del pleistocene superiore: in accordo con questo riferimento è la presenza su alcune unità inferiori del versante occidentale di una copertura di loess riferito, su base paleontologica, alla parte superiore del pleistocene superiore (forno, 1979; 1990). le variazioni altimetriche all’interno delle singole unità, con entità di poche decine di metri, possono essere attribuite in parte all’inclinazione originaria delle superfici, secondo il gradiente del corso d’acqua responsabile del modellamento, e in parte al diverso grado di rimodellamento (fig. 7). la successione fluviale presa in esame è da collegare essenzialmente al sensibile approfondimento erosionale operato entro al rilievo dall’antico reticolato idrografico, in risposta al contemporaneo sollevamento: a tale fenomeno è connessa la formazione delle scarpate modellate nel substrato terziario, con altezza di alcune decine di metri, che separano le diverse unità terrazzate (fig. 8). la genesi delle superfici pianeggianti è da collegare, invece, a fenomeni di erosione laterale associati a episodi di modesta sedimentazione, che interrompono il trend erosionale dominante: in questo contesto la maggiore estensione di alcuni lembi conservati nel versante nordoccidentale, come ad esempio quelli relativi all’unità di v. sambuelli (8n), è indicativa di un più importante episodio di erosione areale da parte del reticolato idrografico. lo sviluppo preferenziale degli elementi fluviali secondo direttrici s-n e se-nw, circa paralleli allo 131la successione fluviale pleistocenica ... spartiacque principale e non collegabili all’andamento dei corsi d’acqua che attualmente incidono il rilievo, suggerisce il riferimento della successione presa in esame ad un precedente reticolato idrografico caratterizzato da gradienti modesti, con decorso parallelo al margine collinare. le ridotte dimensioni dei lembi conservati sono invece indicative di una dissezione da parte del reticolato idrografico attuale, circa ortogonale rispetto al precedente e caratterizzato da sensibili gradienti. malgrado la distribuzione della successione fluviale sia prossima all’attuale alveo del f. po e abbia un andamento ad esso circa parallelo, non è possibile riferirla a quest’ultimo corso d’acqua: i dati riguardanti l’andamento del reticolato idrografico piemontese sono infatti concordi nell’indicare che durante il pleistocene medio e il pleistocene superiore il f. po defluiva in corrispondenza al versante meridionale della collina di torino (forno, 1980; 1982; compagnoni & forno, 1992). partendo dall’osservazione che gli attuali conoidi alpini occupano gran parte della pianura e in particolare lambiscono i versanti collinari (fig. 9), sembra invece verosimile ipotizzare come la successione terrazzata descritta sia formata da lembi originariamente appartenenti al settore distale di tali conoidi: i lembi relitti, coinvolti nell’intensa deformazione collinare, avrebbero successivamente perso l’originaria continuità con la pianura. considerando la successione con maggiore dettaglio si può effettuare una distinzione tra due settori altimetrici differenti, indicati rispettivamente come a e b (cfr. inserto 5 di tav. 1), comprendenti ognuno una successione di unità. per il settore altimetrico superiore (a) le unità mostrano caratteristiche diverse tra il versante occidentale (unità 8w÷10w) e quello nordoccidentale (unità 6n÷14n) per quanto riguarda il numero di unità ricostruibili, la distribuzione altimetrica dei lembi e l’inclinazione complessiva, rispettivamente verso s e verso nw; inoltre, esclusivamente per il versante occidentale, è possibile effettuare una correlazione dei lembi fluviali con quelli conservati nel versante meridionale e si ha la locale presenza di relitti di meandri incastrati (11w). l’insieme di questi elementi consente di ipotizzare che le successioni rinvenute nei due versanti non siano tra loro correlabili e suggerisce come durante il modellamento della parte più antica della successione, riferita a gran parte del pleistocene medio, il rilievo fosse di pertinenza di due distinti bacini idrografici drenanti rispettivamente verso sud per il versante occidentale e verso ne per quello nordoccidentale. a confermare tale ipotesi sono la continuità tra le forme e i depositi del versante occidentale con quelli del versante meridionale descritti in compagnoni & forno (1992) e i dati mineralogici sintetizzati più avanti. per il settore altimetrico inferiore (b) (cfr. inserto 5 in tav. 1) la continuità laterale delle forme e l’inclinazione confrontabile verso n-ne per entrambi i versanti (unità 1÷5) indica invece una buona correlabilità tra gli elementi conservati nei due settori: tale osservazione consente di ipotizzare che nel pleistocene superiore l’intera area sia venuta a fare parte di un unico bacino drenato da un corso d’acqua con deflusso verso ne. non esiste invece continuità con le forme del versante meridionale, rispetto alle quali sono separate da uno spartiacque corrispondente alla dorsale di moncalieri. di interpretazione problematica è infine la mancanza di lembi fluviali nel settore di valsalice sviluppato in corrispondenza del limite fra i versanti occidentale e nordoccidentale, caratterizzato da un particolare assetto geologico per la presenza di evidenti discontinuità strutturali, tuttora in corso di studio. le evidenze morfologiche suggeriscono che tale settore sia interessato da un’intensa erosione da parte del reticolato idrografico attuale e da estesi fenomeni gravitativi: questa evoluzione impedisce di chiarire se esso abbia rappresentato per lungo tempo un settore di spartiacque fra i due versanti interessati dal modellamento fluviale o se vi fossero lembi fluviali attribuibili a uno dei due versanti, in seguito cancellati. dalle considerazioni precedentemente esposte, integrate con i risultati delle analisi mineralogiche dei depositi fluviali tuttora in corso (forno et al., 2002), è possibile individuare come bacino di provenienza della successione fluviale descritta i bacini alpini occidentali, con un apporto principalmente dai fiumi dora riparia e stura di lanzo, e proporre un’ipotesi interpretativa dei bacini di provenienza dei diversi elementi che la costituiscono (cfr. inserti 2 e 3 in tav. 1). 132 fig. 9 gli estesi conoidi legati ai corsi d’acqua alpini, attuali affluenti di sinistra del f. po, lambiscono il margine settentrionale della collina di torino, visibile in primo piano. the wide alpine aprons connected to the alpine watercourses tributary of the river po lap the northern margin of the collina di torino, in the foreground. g. forno & s. lucchesi fig. 8 il lembo di superficie terrazzata del monte dei cappuccini (q. 284, unità 2) appare sospeso rispetto all’alveo attuale del f. po tramite una scarpata con altezza di circa 50 m. the monte dei cappuccini terraced surface (q. 284, unit 2) appears suspended from the present river po by a 50 metreshigh scarp. la successione terrazzata descritta in origine costituiva quindi il settore distale dei conoidi alpini che lambivano il margine della collina di torino, in intenso sollevamento. i lembi di questi conoidi conservati nell’area di pianura (compresi in piccola parte in tav. 1 sulla sinistra del f. po) hanno mantenuto sostanzialmente le caratteristiche originarie; i lembi conservati invece nell’area collinare sono stati progressivamente coinvolti nel sollevamento del rilievo e sensibilmente deformati, fino a raggiungere l’attuale sviluppo altimetrico, sospeso rispetto alla pianura; contemporaneamente a questa evoluzione le superfici sono state dissecate dal reticolato idrografico che si organizzava progressivamente nel settore collinare, fino ad assumere l’attuale conservazione in lembi relitti. inizialmente, fino a gran parte del pleistocene medio, nel settore in esame erano presenti almeno due corsi d’acqua principali che defluivano rispettivamente verso sw e ne; successivamente, durante il pleistocene superiore, anche il corso d’acqua più meridionale deviò il proprio corso, andando verosimilmente a confluire con quello più settentrionale. il settore collinare esaminato è stato quindi interessato da una profonda modificazione dell’assetto geologico, indotta dall’evoluzione geodinamica: da area inizialmente appartenente alla pianura padana, caratterizzata dal prevalere dell’erosione areale accompagnata da una limitata sedimentazione fluviale, è venuta a fare parte dell’area collinare, interessata invece dal prevalere dell’approfondimento erosionale. un ulteriore elemento che può avere concorso all’attuale assetto altimetrico della successione fluviale riguarda la possibile deformazione differenziale tra il settore settentrionale e quello meridionale del rilievo: si può ipotizzare che tale comportamento differenziale abbia, in un primo tempo, favorito l’esistenza di due diversi bacini idrografici e, in un secondo tempo, deformato in modo differenziale la successione fluviale sui due versanti. la ricostruzione proposta è inquadrabile nell’ambito dell’evoluzione cinematica recente che ha coinvolto la collina di torino, rappresentata in particolare dallo sviluppo di due fenomeni tra loro strettamente connessi: il progressivo sollevamento dell’edificio strutturale della collina di torino e la migrazione verso nw del suo margine esterno (fig. 10). confrontando il riferimento cronologico della successione fluviale con la sua distribuzione altimetrica, e quindi con il dislivello di circa 400 m che essa mostra, è possibile stimare che tra il pleistocene medio e l’olocene si sia verificato un sollevamento con velocità media di circa 1 mm/anno. i tassi di sollevamento così ottenuti sono congruenti con i valori desunti dalle livellazioni geodetiche relative al primo sessantennio dello scorso secolo (arca & beretta, 1985), che individuano nei rilievi collinari i valori di massimo sollevamento dell’intera area piemontese (> 3 mm/anno). la presenza, entro la successione terrazzata descritta, di scarpate di erosione con entità diversa per le diverse fasce altimetriche consente di ipotizzare che tale tasso di sollevamento non sia stato costante nel tempo, ma che si siano succeduti momenti di minore o maggiore attività geodinamica. ringraziamenti si ringrazia il professor f. carraro per la lettura critica del manoscritto e gli utili suggerimenti forniti. lavori citati arca s. & beretta g. (1985) prima sintesi geodeticageologica sui movimenti verticali del suolo nell’italia settentrionale (1897-1957). boll. geod. sc. aff. , 2, 125-156. arduino e., barberis e., carraro f. & forno m. g. (1984) estimating relative ages from ironoxide/total-iron ratios of soils in the western po valley, italy. geoderma, 33, 39-52, amsterdam. boano p. & forno m. g. (1997) evoluzione morfologica quaternaria del versante occidentale della collina di torino. geoitalia, 1° forum italiano di scienze della terra della fist (bellaria, 5-9 ottobre 1997), 2, 221-222. boano p., carraro f., forno m. g., giardino m., lozar f., lucchesi s., perotto a., piana f. & polino r. (2000) l’evoluzione recente della collina di torino: un esempio di interazione tra attività geodinamica e morfogenesi. in: carulli g. b. & longo salvator g. (eds.) riassunti delle comunicazioni orali e dei posters della 80a riunione estiva della società geologica italiana (trieste, 6-8 settembre 2000). ed. univ. trieste, 81-83. b o a n o p., f o r n o m. g. & l u c c h e s i s. (2002) deformazione pleistocenica della collina di torino dedotta dal modellamento della successione fluviale. in: fioraso g., malusà m., mosca p. & tallone s. (eds.) riassunti della 81a riunione estiva della società geologica italiana “cinematiche collisionali: tra esumazione e sedimentazione” (torino, 10-12 settembre 2002). litografia geda, nichelino (to), 52-53. b o a n o p., f o r n o m. g. & l u c c h e s i s. (2004) pleistocene deformation of the collina di torino inferred from the modelling of their fluvial succes133 fig. 10 la sella in contropendenza che separa il lembo terrazzato del monte dei cappuccini dal resto del rilievo, connessa con l’incisione fluviale riferibile all’unità 1, suggerisce che il sollevamento della collina di torino e la migrazione del suo margine settentrionale determinino il progressivo inglobamento nel rilievo di settori inizialmente di pianura. the position of the monte dei cappuccini terraced surface, separated by an evident fluvial cut from the relief (unit 1), suggest that the uplift of the collina di torino and the migration of its northern margin produced the progressive embedding in the relief of initial plain areas. la successione fluviale pleistocenica ... sion. il quaternario, it. journ. quat. sc., 17, 145150. bonsignore g., bortolami g. c., elter g., montrasio a., petrucci f., ragni u., sacchi r. & zanella e. (1969) note illustrative della carta geologica d’italia alla scala 1:100.000, fogli 56 e 57 “torino” e “vercelli”, iia ed., serv. geol. it., roma. bortolami g. c., crema g. c., malaroda r., petrucci f., sacchi r., sturani c., tagliavini s. & venzo s. (1969) foglio 56 “torino” della carta geologica d’italia alla scala 1:100.000. iia ed., serv. geol. it., roma. carraro f. (1976) diversione pleistocenica nel deflusso del bacino piemontese meridionale: un’ipotesi di lavoro. gr. st. quat. pad., 3, 89-100. carraro f., forno m. g. & valpreda e. (1982) field trip in northern italy. guidebook. september 15th. piedmont: asti area . i.g.c.p. 73/1/24 pr. quaternary glaciations in the northern hemisphere. final session. september 1/17th 1982. franceitaly. litografia massaza & sinchetto, 24 pp. carraro f., forno m. g., ricci b. & valpreda e. (1987) neotectonic map of italy (scale 1: 500.000): foglio1. in: ambrosetti p., bosi c., carraro f., ciaranfi n., panizza m., papani g., vezzani l. & zanferrari a. (eds.) neotectonic map of italy. c.n.r., progetto finalizzato geodinamica. litografia artistica cartografica, firenze. carraro f., collo g., forno m. g., giardino m., maraga f., perotto a. & tropeano d. (1994) l'evoluzione del reticolato idrografico del piemonte centrale in relazione alla mobilità quaternaria. in: polino r. & sacchi r. (eds.) atti del convegno "rapporti alpi-appennino" e guide alle escursioni peveragno (cn), 31 maggio-1 giugno 1994. ac. naz. sc., 14, 445-461. carraro f., forno m. g., giardino m. & paro l. (2005) field trip guide.14th meeting of the association of european geological societies, september 23th 2005, torino hill. il quaternario, it. journ. quat. sc., 18 (2), 3-55. consiglio nazionale delle ricerche (1990) structural model of italy, scale 1:500.000, sheet 1. progetto finalizzato geodinamica, s.e.l.c.a., firenze. compagnoni r. & forno m. g. (1992) significato geologico di depositi fluviali ghiaiosi pleistocenici medi nella collina di torino. il quaternario, it. journ. quat. sc., 5, 105-122. forno m. g. (1979) il loess della collina di torino. revisione della sua distribuzione e della sua interpretazione genetica e cronologica. geogr. fis. dinam. quat., 2, 105-124. forno m. g. (1980) evidenza di un drenaggio abbandonato nel settore settentrionale dell’altopiano di poirino (prov. di torino). geogr. fis. dinam. quat., 3, 61-65. forno m. g. (1982) studio geologico dell’altopiano di poirino. geogr. fis. din. quat., 5, 129-162. forno m. g. (1990) aeolian and reworked loess in the turin hills (northwestern italy). quaternary international, 5, 81-87, oxford. forno m. g., ben g., boano p., bocca p., boero v. & compagnoni r. (2002) lembi di depositi fluviali provenienti dai bacini alpini nordoccidentali sulla collina di torino presso villa gualino (nw italy) il quaternario, it. journ. quat. sc., 15, 175-185. sturani (1975) explanatory notes on western alps (from the sestri-voltaggio line to the val d’ossola). in: ogniben l., parotto m. & praturlon a. (eds), structural model of italy. quad. la ricerca scientifica, 90, 149-174. piana f. & polino r. (1994) la zona transpressiva di rio freddo e l’evoluzione convergente della collina di torino e del monferrato durante il terziario. atti tic. sc. terra, ser. spec., 1, 167180. rizzetto f., mycielska-dowgiallo e. & castiglioni g.b. (1998) some aeolian features in the po plain near este (north italy). geogr. fis. din. quat., 21, 245253. 134 ms. ricevuto il 27 aprile 2005 testo definitivo ricevuto il 19 ottobre 2005 ms. received: aprile 27, 2005 final text received: october 19, 2005 g. forno & s. lucchesi imp.geremia& coastal geomorphosites of the isles of lipari and stromboli (aeolian islands, italy): new potential for geo-tourism francesco geremia1 & raniero massoli-novelli2 1dipartimento di scienze della terra, università degli studi di messina, salita sperone 31, 98166 messina email: fgeremia@unime.it 2coordinator of the geosites sigea working group, via della mendola 85, 00135 roma, italy email: massoli@tiscali.it abstract: f. geremia & r. massoli-novelli, coastal geomorphosites of the isles of lipari and stromboli (aeolian islands, italy): new potential for geo-tourism. (it issn 0394-3356, 2005). after illustrating the main geological, volcanological and geomorphological characteristics of the aeolian islands and, in particular, of lipari and stromboli – the two main isles of the archipelago – their most important coastal geomorphosites are individuated. considering their high level of geological and geomorphological interest, two geo-tourism itineraries by boat are planned – one for each island – to promote their coastal landscape of volcanic origin. six coastal geomorphosites or groups of geomorphosites of elevated scientific and educational value are selected for each itinerary. the itinerary for the island of lipari begins in its eastern side with a panoramic view of the famous castle of lipari, built on a imposing rhyolitic lava dome. it continues toward the northern coast, where there are considerable pumice quarries and a rare coarse clastic beach, characterized by the presence of dark volcanic gravels and pebbles and light-coloured pebbles of pumice, to finish in the southern side with the observation of two notable volcanic pinnacles (pietralunga and pietra menalda). the itinerary for the island of stromboli begins from the pier of scari, characterised from a dark-coloured sandy beach and continues toward ginostra, where it is possible to run along the first geological-historical path of aeolian islands. the itinerary continues toward northwest with the impressive panoramic view of the “sciara del fuoco”, a rare landscape in the mediterranean, and to finish around the neck of strombolicchio, the last evidence of a vast volcanic edifice. emphasis is given to the importance of this new kind of cultural tourism, named “geo-tourism”, according the principles of sustainable development and based on the promotion and conservation of the unique geomorphological-volcanological heritage of aeolian islands. riassunto: f. geremia & r. massoli-novelli, geomorfositi costieri delle isole lipari e stromboli (isole eolie, italia): una nuova potenzialità per il turismo. (it issn 0394-3356, 2005). dopo la illustrazione delle principali caratteristiche geologiche, vulcaniche e geomorfologiche delle isole eolie in generale ed in particolare di lipari e stromboli, le due principali isole dell’arcipelago, ne vengono individuati i principali geomorfositi costieri. in base alle valenze geologiche-geomorfologiche identificate vengono progettati due itinerari geoturistici, uno per isola, da dedicare al paesaggio costiero di origine vulcanica e da effettuare in barca. per ogni itinerario sono stati scelti sei geomorfositi o gruppi di geomorfositi, scelti tra i più importanti e con maggiore valenza didattica, e per ognuno di essi è stato progettato uno stop, con osservazioni da effettuare a seconda delle situazioni o dalla barca o a terra. l’itinerario per l’isola di lipari inizia ad est con lo splendido castello di lipari che sorge su un imponente bastione di lava riolitica, prosegue verso nord con le grandi cave di pomice e con la rara spiaggia di porticello, caratterizzata dalla presenza di ciottoli di lava nera e di pomice bianca, per terminare a sud con i due notevoli pinnacoli lavici di pietralunga e pietra menalda, che si ergono in mezzo al mare. l’itinerario per l’isola di stromboli inizia dal molo di scari, caratterizzato da una spiaggia con sabbia vulcanica completamente nera, scende verso ginostra, ove si può percorrere a terra un già collaudato sentiero geologico, continua a nord-ovest con l’impressionante sciara del fuoco, un paesaggio unico nel mediterraneo, e termina di fronte allo scenografico “neck” di strombolicchio, residuo dello smantellamento di un ben più vasto edificio vulcanico. viene sottolineata l’esigenza di questa nuova forma di turismo culturale che è il “geoturismo”, valido sotto il profilo dello sviluppo sostenibile, basato sulla spiegazione, promozione e conservazione del prezioso, talvolta unico, patrimonio geomorfologico-vulcanologico delle isole eolie. keywords: geomorphosites, geo-tourism, lipari, stromboli, aeolian islands, tyrrhenian sea. parole chiave: geomorfositi, geoturismo, lipari, stromboli, isole eolie, mar tirreno. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 233-244 1. introduction the potential for geo-tourism is high all over sicily, and especially in the aeolian islands. as the geological features of these islands are relevant, the whole archipelago was included in the list of unesco natural assets, on the grounds that: “the volcanic landforms of the aeolian islands represent classic features in the continuing study of volcanology worldwide”. the coastal geomorphosites of the aeolian islands typically witness the history and dynamics of past and recent volcanic events and geomorphological processes affecting the archipelago. they may be analysed from different perspectives: from landscape description to scientific interpretations, from encouraging interest in geological knowledge to examining the economic role of geo-tourism initiatives. the identification and study of coastal geomorphosites from the viewpoint of sustainable tourism is only the first step towards intelligent fruition of the aeolian archipelago. geosite assessment, selection and protection criteria should satisfy not only scientific 234 f. geremia & r. massoli-novelli needs but also the need for social fruition. the fundamental parameters of this type of assessment are essentially as follows: scientific value – educational value – rareness – degree of conservation – visibility and accessibility – extra value, also considering naturalistic, archaeological etc. aspects (arnoldushuyzendveld et al., 1995; panizza & piacente, 2002; d’andrea et al., 2003; massoli-novelli, 2003a; 2003b). organising geological and geomorphological excursions allows various advantages, such as promoting the knowledge of earth sciences, which is so poorly appreciated among the population at large. this would offer new professional opportunities to young geologists and naturalists and result in a better distribution of tourists: not only in the months of july and august but also in the spring and autumn. in this way the aeolian territory would benefit from a renewed socio-economic balance, which has long been sought after by local administrations. taking into account the high scientific and educational value of the coastal scenery in lipari and stromboli, two geo-tourism itineraries by boat are planned. six coastal geomorphosites or groups of geomorphosites are individuated for each itinerary. they were analysed through a their detailed geomorphological survey integrated with information provided by scientific and historical literature. the aim of these two geological itineraries is to explain to tourists visiting the aeolian islands every year, that the input of energy into a coastal system via waves is one of the main forces determining coastal processes and how the coast-forming volcanic materials of lipari and stromboli act in response to mechanical wave erosion and mass movement processes. besides, it is important to investigate how the tourism fruition of present coastal scenery can be developed in presence of a high value of vulnerability induced by human activity and, above all, to volcanic hazards consequences. 2. general geological setting the aeolian islands are located in the south-eastern tyrrhenian sea facing the northern coast of sicily (fig. 1). they provide an outstanding record of volcanic island-building and destruction processes and ongoing volcanic phenomena. studied since at least the 18th century, these islands have permitted to investigate on two types of eruption (vulcanian and strombolian) and so have featured prominently in the education of all geoscientists for over 200 years. the archipelago of the aeolian islands is made up of seven main islands (lipari, vulcano, panarea, stromboli, salina, filicudi ed alicudi) and several seamounts and islets, along the internal margin of the apennine -maghrebian chain. it is correlated to the complex geodynamic situation of the mediterranean area which has been site of the collision between the african and eurasian plates, with a trending convergence (barberi et al., 1974). the aeolian islands are the part emerged of a large submarine volcanic basement extending for around 200 km, having a typical arc-shaped structure. the depth of the basement from which the seven islands emerge ranges from 1000 and the 2000 m b.s.l. they consist mainly of volcanic products, spanning in age from about 400 ka to the present, and subordinately from late-quaternary marine deposits. vertical crustal movements of the volcanic edifices have been interpreted as being the result of interaction between episodic eruptive events and neo-tectonic processes, both transitory and active on a local scale (calanchi et al., 1996; 2002). seismic and volcanic activities linked to quaternary tectonics and marine erosion, both pleistoceneholocene and present, are the main factors responsible for the great coastal diversity of the aeolian islands, both emerged and submerged (romagnoli et al., 1993). the volcanic coastal landscape of aeolian islands is particularly suitable for physical processes (e.g. mechanical wave erosion, mass movement and longshore sediment transport). these processes have played an important role in the development of present coastal scenery with formation of a great diversity of coastal features (e.g. plunging and composite cliffs, embayed and pocket beaches, sea arches and caves, islets and stacks, etc.). all these coastal features develop chiefly along the structural weaknesses (e.g. the joints and the fault planes) or as the result of a differential erosion of dykes. instead, other marine processes, such as bioerosion and chemical and salt weathering, are absent or insignificant. fig. 1 location of the isles of lipari and stromboli in the aeolian archipelago (south-eastern tyrrhenian sea). inquadramento geografico delle isole di lipari e stromboli nell’arcipelago eoliano (mar tirreno sudorientale). 3. the isle of lipari 3.1. geological framework lipari is the largest island of the archipelago with a surface extending for 38 km2, a maximum length of about 9.5 km (north-south) and a width of 7 km (eastwest). during the neolithic age it was one of the rare sources of obsidian in the mediterranean and it was also famous as the most important trading station for kaolin and pumice. from a geological and volcanic viewpoint, the isle of lipari – like stromboli is the emerged part of a large volcanic edifice, rising from the sea floor at a depth of about 1000 m b.s.l.. although the geological evolution of lipari is complex, it can be divided in two phases of different volcanic activity, separated by a long period of dormancy (about 45,000 years), revealed by evident subaerial and marine erosional surfaces. the volcanic activity of the first period (paleolipari) starts about 230,000 years bp with the emission of products composed of basalt and andesite. post-erosional volcanic activity begins at about 42,000 years bp, with very different eruptive styles and magma composition, as testified by the emission of evolved magmatic products (rhyolite – obsidian lava flows) and large amounts of surge deposits (pumice deposits). the last volcanic activity in lipari occurred between 16,800 and 1,400 years bp and is located in its north-eastern sector. this important activity results in a substantial emission of pumice surge deposits on monte pilato and of exceptional obsidian and rhyolite lava flows in rocche rosse (pichler, 1980; tranne et al., 2000). recent dating establishes that the last eruption took place about 1400 years bp, covering the fourth and fifth century roman remains in the acropolis of lipari with a thin layer of pumice (calanchi et al., 1996; tranne et al., 2000). the coastal scenery of lipari is varied and rugged; it is characterised by the presence of headlandembayment sequences with numerous sea-stacks, arches and caves. embayed beaches with sands, gravel and cobbles are principally prevalent along the eastern and northern side of the island, from the port of lipari to the headland of punta del legno nero. high and steep, plunging and composite cliffs dominate along the western and southern coast; although boulder beaches are present on the south-western coast between punta le grotticelle and punta crepazza, and a very sorted sandy beach, nourished naturally by the adjacent landslide and detrital deposits, is embayed in the valle muria bay. in addition, mechanical wave erosion and mass movement are the dominant exogenetic processes along the coast of lipari (fig. 2). 3.2. coastal geomorphosites and geo-tourism there are numerous pathways on the isle of lipari connecting various localities but some of these tracks are quite difficult to follow, so it is more interesting to explore the extraordinary coastal scenery of lipari sailing around the island by boat (fig. 2). a complete tour around the island, taking about 9 hours and including two stops at porticello and valle muria beaches, is proposed. it is better to sail round the island anticlockwise, so as to have a good view of the eastern side during the morning and the western side during the afternoon with a spectacular panoramic 235coastal geomorphosites of ... view of its southern side at sunset. in this way the following coastal geomorphosites of volcanic origin can be observed very well: stop n. 1 – rocca del castello cliff the famous castle of lipari is built on a strongly eroded rhyolitic lava dome, linked to the eruptive centre of monte guardia (some 20,000 years bp). at the base of cliff, evidences of progressive rock falls can be observed, which have brought the margin of the cliff up to the castle’s ancient spanish walls. next to the rocky cliff, the interaction between endogenetic volcanic phase and exogenetic processes (e.g. mechanical wave erosion and mass movement) can be observed, together with evidence of human activities and works carried out to protect ancient buildings (table 1). tab. 1 dominant landform and processes, vulnerability and accessibility of the first stop selected around the coast of the island of lipari. morfologia e processi dominanti, vulnerabilità ed accessibilità del primo stop selezionato intorno alla costa dell’isola di lipari. 236 stop n. 2 – campo bianco pumice quarry and porticello beach the porticello beach is characterised by the presence of berms with dark volcanic gravels and pebbles and bigger, roundish, light-coloured pebbles of pumice (table 2). at north of porticello beach the rhyolite-obsidian lava flow of rocche rosse (1,400 years bp) shows spectacular convoluted flow foliation structures visible along the abandoned cliff. to the south on the eastern side of monte pilato there is the very large campo bianco pumice quarry which has long quays on the coast, where the extracted rock is loaded onto ships (fig. 3). in the past the discarded materials from the pumice quarry formed a completely white gravelly f. geremia & r. massoli-novelli fig. 2 the geological-tourism itinerary around the isle of lipari. location, dominant landforms and processes of the main coastal geomorphosites. l’itinerario geologico-turistico intorno all’isola di lipari. ubicazione, morfologia e processi dominanti dei principali geomorfositi costieri. 237 beach, much appreciated by tourists; at present the pumice extraction is incompatible with a sustainable development of the island. stop n. 3 – le torricelle sea stack the sea stack of le torricelle, some 32 m high, is an interesting coastal geomorphosite, characterised by plunging cliffs with a pillar-like structure originated by effusive activity of paleolipari volcanic centres (223,000 150,000 years bp) and covered by conglomerate levels with pebbles and pyroclastic deposits. its upper coastal geomorphosites of ... tab. 2 dominant landform and processes, vulnerability and accessibility of the second stop selected around the coast of the island of lipari. morfologia e processi dominanti, vulnerabilità ed accessibilità del secondo stop selezionato intorno alla costa dell’isola di lipari. tab. 3 dominant landform and processes, vulnerability and accessibility of the third stop selected around the coast of the island of lipari. morfologia e processi dominanti, vulnerabilità ed accessibilità del terzo stop selezionato intorno alla costa dell’isola di lipari. fig. 3 lipari, stop n. 2. the large pumice quarry at campo bianco. lipari, stop n. 2. l’estesa cava di pomice di campo bianco. 238 extremity appears flattened by sea abrasion and is to be linked to elevated marine terraces recognised along the western coast of lipari (table 3). the ancient uplifted shorelines are the result of interaction between sealevel fluctuations in the late quaternary and vertical movement of the volcanic island (calanchi et al., 2002). stop n. 4 – valle muria bay valle muria is a narrow and elongated wave-dominated embayed beach confined between the two headlands of and punta di levante. tuff and lapilli tuff (hydromagmatic activity) and scoriae of first period (223,000 150,000 years bp) crop out along the promontory of punta di ponente; they are locally characterised by fumarole levels, ranging in colour from yellow to white and red (table 4). at punta di levante the remains of an ancient lava dome, belonging to the punta del perciato eruptive complex, have been overlaid by a massive brown ash tuff deposit (brown tuffs) with intercalation of one black coarse ash layer related to the salina volcanic activity (tranne et al., 2000). stop n. 5 – punta del perciato headland the rocky headland of punta del perciato is the last evidence of a thick, rhyolitic lava dome, dating from 20,300 – 42,000 years bp. concentric ramp structures with excellent examples of onion-like flux exfoliation can here be observed. in addition, the site is characterised by the presence of a sea arch with vertical walls; it is a significant indicator that a strong wave action in all two sides of the promontory (table 5). stop n. 6 – pietralunga and pietra menalda pinnacles the beautiful pietralunga and pietra menalda pinnacles, some 60 and 25 m high, are the last witnesses of a wide volcanic structure which was dismantled by marine erosion (fig. 4). they were formed by the same volcanic activity of fourth period (42,000 20,300 years bp) which originated the promontory of punta del perciato. these two sea stacks are characterised by steeply descending cliffs that pass far below sea level without any shore platform and are attacked continuously by wave erosion (table 5). 4. the isle of stromboli 4.1 – geological framework stromboli is the most active volcano in europe and is famous worldwide on account of its typical “strombolian” activity, which consists of ejection of ash, lapilli and lava bombs with rare lava effusions of short duration. stromboli is also considered an extremely important field laboratory for volcanic hazard assessment. it is the northernmost island of the aeolian archipelago and covers an area of 12.2 km2. stromboli with an elevation of 924 m a.s.l. forms a steep and f. geremia & r. massoli-novelli tab. 4 dominant landform and processes, vulnerability and accessibility of the fourth stop selected around the coast of the island of lipari. morfologia e processi dominanti, vulnerabilità ed accessibilità del quarto stop selezionato intorno alla costa dell’isola di lipari. fig. 4 lipari, stop n. 6. the beautiful 60 m high pietralunga volcanic pinnacle. lipari, stop n. 6. l’eccezionale faraglione di pietralunga, alto 60 metri s.l.m. uniform volcanic cone which rises from a depth of about 2400 m in the tyrrhenian sea. the island of stromboli was affected by several collapses, which took place in two main stages: the older one, characterised by three concentric caldera collapses and several pyroclastic eruptions related to a flank collapse toward south-east, and the younger one, characterised by two sector collapses, one flank collapse towards north-west and predominant lava effusions (pasquarè et al., 1993). the geological evolution of stromboli is recorded in its subaerial part for a time span from about 100,000 years bp up to the present. four major periods (paleostromboli, vancori cicles, neostromboli and recent stromboli) have been recognised and further subdivided into 30 volcano-stratigraphic units. pyroclastites (ignimbrites, surge and lahar deposits) predominate over lavas (latites) during the first two periods, while the more recent products are generally basalts, with shoshonitic composition (horningkjarsgaard et al., 1993; rosi, 1980). as regards volcanic hazard, stromboli is at present characterised by a peculiar state of permanent activity consisting of mild intermittent explosions and continuous gas steaming. from time to time this normal activity is interrupted by eruptive crises characterised by either lava emission or more violent explosions. there are on average 2.1 events per year of major explosions with fallout of large blocks and incandescent bombs up to a distance of about 1.5 km from the craters. more violent paroxysms with a larger volume of ejected material and a broader spectrum of phenomena have an occurrence of one event every 10-15 years (barberi et al., 1993). the island of stromboli has a high vulnerability to volcanic hazards (e.g. explosive eruption and volcanic landslides) and large tsunamis could also take place as the effect of huge landslide at “sciara del fuoco” (tinti et al., 1999). the morphology of this island is rugged and jagged, owing to continuous volcanic eruptions and marine erosional processes. flat areas, made up of emerged marine terraces, are very rare. they are site of the two main human settlements: the villages of stromboli in the north-east side and of ginostra in the south-west side. the coastal scenery is characterised by the presence of cliffs with more or less gentle slopes. only on the north-east side the coastal slope is gentle and grass-covered with rich soil and fields under cultivation. some sandy and pebbly beaches are also found, mainly along the north-east side. a dark-coloured sandy foreland, between scari and punta lena, extends out from the coast towards the islet of strombolicchio. it is a significant indicator that two dominant swells are in opposition (fig. 5). 4.2 – coastal geomorphosites and geo-tourism stromboli is an island at high volcanic risk, where it is no longer possible to walk along high-altitude footpaths without an authorised guide. it is, therefore, advisable to explore its rugged coastal landscape by sailing along it, thus reaching also the islet of strombolicchio, some 1.3 miles away from stromboli’s north-eastern coast. the complete tour by boat around the island takes about 5 hours, including a stop at the village of ginostra (fig. 5). starting from the pier of scari and proceeding clockwise, the most important coastal geomorphosites of volcanic origin are as follows: stop n. 1 – le schicciole valley along the eastern coast, three steep small valleys filled with pyroclastic material can be seen. these are volcano-tectonic collapse structures, named “le schicciole” and formed some thousands of years ago along the western flanks of stromboli volcano. they are similar on a smaller scale to the famous “sciara del 239coastal geomorphosites of ... tab. 5 dominant landform and processes, vulnerability and accessibility of the fifth and sixth stop selected around the coast of the island of lipari. morfologia e processi dominanti, vulnerabilità ed accessibilità del quinto e sesto stop selezionati intorno alla costa dell’isola di lipari. fuoco” depression, which will be described in one of the next stops. in fact, also in this case, the hollow spaces left after collapse were later filled by soft and cohesionless pyroclastic materials with respect to the harder, ancient flows which form a sort of container (table 6). stop n. 2 – secche di lazzaro underwater arches in the area surrounding secche di lazzaro the coast has an exposure between 90° and 120°n and is still sheltered from the strong north-westerly mistral wind. since sea dismantling activity is less intense, the “lazzaro pyroclastites” (some 4,000 years bp) crop out on top of the neostromboli lava flows (some 14,000 years bp). here there are, therefore, excellent conditions for observing the various degrees of incidence of erosional processes on the lavas and dip-downstream pyroclastic deposits. nearby, at secche di lazzaro, snorkelling allows the viewing of magnificent rock arches, appearing a few meters below the sea surface. these structures were carved into pyroclastic deposits by wave-motion when the sea level was lower than it is now (table 7). 240 f. geremia & r. massoli-novelli fig. 5 the geological-tourism itinerary around the isle of stromboli. location, dominant landforms and processes of the main coastal geomorphosites. l’itinerario geologico-turistico intorno all’isola di stromboli. ubicazione, morfologia e processi dominanti dei principali geomorfositi costieri. stop n. 3 – ginostra secche di lazzaro (first “geological-historical path” of the aeolian islands) ginostra is a small coastal village naturally isolated from the lava flows of the ever-active stromboli volcano. the village is made up of a cluster of very basic, simple houses, still with no running water or electricity. owing to the high landslide susceptibility of the volcano’s flanks, there are no road connections, not even footpaths, between the villages of ginostra and stromboli. the passengers arriving by ferryboat from naples, messina and the other aeolian islands are transferred into small boats that eventually take them to the “pertuso”, the small natural harbour dug by the sea into the black basalt lava. at present, the construction of a little harbour similar to that of stromboli is in progress, in order to offer safe conditions to the local population and the numerous summer tourists (table 7). some years ago, the first “geological-historical path” of the aeolian islands, from ginostra to secche di 241coastal geomorphosites of ... tab. 6 dominant landform and processes, vulnerability and accessibility of the first stop selected around the coast of the island of stromboli. morfologia e processi dominanti, vulnerabilità ed accessibilità del primo stop selezionato intorno alla costa dell’isola di stromboli. tab. 7 dominant landform and processes, vulnerability and accessibility of the second and third stop selected around the coast of the island of stromboli. morfologia e processi dominanti, vulnerabilità ed accessibilità del secondo e terzo stop selezionato intorno alla costa dell’isola di stromboli. lazzaro, was opened (fig. 6). it is about 1 km long and its volcanological features of neostromboli lava flow (13,800 years bp) are particularly interesting: pahoehoe basalt lavas on the path, latitic dykes cutting through it, ignimbrite deposits and their spectacular erosional features, high-energy coastal erosion, with enormous rounded basalt stones and underwater arches carved into pyroclastic rocks (massoli-novelli, 1999). stop n. 4 – punta chiappe dykes punta chiappe is the site where the major volcanological and geomorphological features of stromboli can be observed better than anywhere else: the vertical lava dykes (latitic in type of timpone del fuoco about 6,000 years bp) which radially cut through the main volcanic edifice. owing to differential erosion, these dykes clearly emerge as brownish walls from the soft and black pyroclastites which surround them. this series of vertical dykes runs along the west flanks of the collapsed structure which gave origin to the “sciara del fuoco”, described below. at the foothill of the volcano the dykes stretch out into the sea giving rise to a series of small sea stacks, strongly exposed to northern wave activity (table 8). stop n. 5 – sciara del fuoco depression the “sciara del fuoco” depression is an exceptional coaxial semicircular escarpment, defined as a large horseshoe-shaped amphitheatre, opened at the northwest end continuing below sea level (romagnoli et al., 1993). it is located along the western slope of the island where most of the volcano’s lava and explosive products are accumulated. this slope is considerably high – some 400 m a.s.l. – with a slope angle of about 35°, and offers an impressive view when observed from a boat. the “sciara del fuoco” is formed as consequence of the youngest flank collapse of stromboli volcano (pasquarè et al., 1993) and it is made up of lateral lava flows and cohesionless deposits constantly moving along the slope. these deposits are composed of surge materials, such as scoriae, pumice and volcanic sand, erupted from the volcano’s active vents, which are located in a depression called “fossa” at an altitude of 700 m. the origin of this concave landform dates from 510,000 years ago, following a series of volcano-tectonic collapses (13,800 years bp) which led to the formation of a 2 km long longitudinal depression which continues underwater in a large submarine canyon up to a depth of 1700 m. in its more superficial part, the walls of the canyon are 150-200 m high and decrease progressively until they gradually disappear beyond 1000 m in depth (romagnoli et al., 1993). the floor of this submarine depression constantly receives the materials erupted by the volcano, offering spectacular views of great interest for geo-tourism as well as for volcanological excursions (table 8). stop n. 6 – strombolicchio neck the neck of strombolicchio (about 49 m a.s.l.) is the only emerged evidence of the earliest evolutional stage (some 200,000 years bp) of stromboli volcanism. it corresponds to the calcalkaline and andesite-basalt compositional neck of a previous volcanic edifice which was completely dismantled by wave-motion (calanchi et al., 1996). owing to its peculiar structure with steep cliffs and position at some 2 km in direction of north-east from stromboli, the islet of strombolicchio, with a powerful lighthouse at the top, has a particular meaning in the social perception of both residents and tourists; consequently, the understanding and promotion of its peculiar volcanological and geomorphological features is of considerable relevance (table 9). 5. conclusions islands are fragile ecosystems with a very delicate balance between environmental, economic and social activities and requirements. it is widely acknowledged that islands should be areas singled out for priority interventions concerning conservation policies and sustainable development set up by public boards, in order to better define developing projects and related conservation actions. these goals may be attained by means of properly planned, well-targeted and culturally innovative interventions. although the classical tourist approach to the aeolian islands can offer plenty of enjoyable leisure activities, it may leave the culturally motivated tourist with a sense of bitterness and frustration, resulting from the lack of appropriate structures capable of appraising the numerous and important geo242 f. geremia & r. massoli-novelli fig. 6 stromboli, stop 3. panoramic viewpoint from south-west of the geological-historical path from ginostra (left) to secche di lazzaro (right). stromboli, stop 3. panoramica da sud-ovest del sentiero geologico-storico da ginostra (a sinistra) a secche di lazzaro (a destra). logical and geomorphological peculiarities of this archipelago. hence the need to provide visitors with alternative routes which take in the classical tourist destinations of these islands, but also leave plenty of space for the satisfaction of new cultural needs. the coastal geomorphosites of lipari and stromboli represent a good example of volcanism controlled by marine processes with a high scientific and educational value. the reconstruction of constructive and destructive phases, leading to present coastal scenery, is essential for a systematic knowledge of the archipelago’s geomorphosites. high levels of vulnerability induced by human activity are perceptible in the eastern side of lipari for the reason that the pumice extraction activity continues and the tourism installations are increasing. instead, very high levels of vulnerability to natural hazards (e.g. explosive eruption and volcanic landslides) are existing in stromboli, mainly along the north-west side. 243 tab. 9 dominant landform and processes, vulnerability and accessibility of the sixth stop selected around the coast of the island of stromboli. morfologia e processi dominanti, vulnerabilità ed accessibilità del sesto stop selezionato intorno alla costa dell’isola di stromboli. tab. 8 dominant landform and processes, vulnerability and accessibility of the fourth and fifth stop selected around the coast of the island of stromboli. morfologia e processi dominanti, vulnerabilità ed accessibilità del quarto e quinto stop selezionato intorno alla costa dell’isola di stromboli. coastal geomorphosites of ... therefore, according the principles of sustainable development, emphasis is given to the importance of this new form of cultural tourism, named “geo-tourism” finalised not only to promotion and conservation of the coastal landscape of volcanic origin, but also to link opportunities of tourism fruition with the problem of the vulnerability to volcanic hazard consequences. references arnoldus-huyzendveld a., gisotti g., massoli-novelli r. & zarlenga f. (1995) i beni culturali a carattere geologico: i geotopi. un approccio culturale al problema geologia tecnica e ambientale, 4, pp. 35-47. barberi f., innocenti f., ferrara g., keller j. & villari l. (1974) evolution of eolian arc volcanism (southern tyrrenhian sea) earth planet. science letters, 21, pp. 269-276. barberi f., rosi m. & sodi a. (1993) volcanic hazard assessment at stromboli based on review of historical data acta vulcanologica, 3, pp. 173188. calanchi n., rossi p.l., sanmarchi f. & tranne c.a. (1996) guida escursionistico vulcanologica delle isole eolie ed. centro studi ricerche storia problemi eoliani, 203 pp. calanchi n., lucchi f., pirazzoli p., romagnoli c., tranne c.a., radtke u., reyss j.l. & rossi p.l. (2002) late-quaternary and recent relative sea-level changes and vertical displacements at lipari (aeolian islands) journ. of quaternary sciences, 17 (5-6), pp. 459-467. d’andrea m., colacchi s., gramaccini g., lisi a. & lugeri n. (2003) un progetto nazionale per il censimento dei geositi in italia geologia dell’ambiente, sigea, 1, pp. 25-33. horning-kjarsgaard i., keller j., koberski u., stadlbauer e., francalanci l. & lenhart r. (1993) geology, stratigraphy and volcanological evolution of the island of stromboli, aeolian arc, italy acta vulcanologica, 3, pp. 21-68. massoli-novelli r. (1999) an important italian geosite: the volcano-island of stromboli (sicily) proceed. iii intern. symp. progeo on the conserv. of the geolog. heritage, madrid, november 23-25, 1999, pp. 410-414. massoli-novelli r. (2003a) una strategia per la geoconservazione: il geoturismo geologia dell’ambiente, sigea, 1, pp. 17-24. massoli-novelli r. (2003b) geositi, geoturismo e sviluppo sostenibile geologia dell’ambiente, sigea, 1, pp. 167-170. panizza m. & piacente s. (2002) geositi nel paesaggio italiano: ricerca, valutazione e valorizzazione. un progetto di ricerca per una nuova cultura geologica. geologia dell’ambiente, sigea, 2, 3-4. pasquarè g., francalanci l., garduno v.h. & ribaldi a. (1993) structure and geologic evolution of the stromboli volcano, aeolian islands, italy acta vulcanologica, 3, 79-89. pichler h. (1980) the island of lipari in: “the aeolian islands. an active volcanic arc in the mediterranean sea”. rend. soc. it. miner. petrol., 36 (1), pp. 415-440. romagnoli c., kokelaar p., rossi p.l. & sodi a. (1993) the submarine extension of sciara del fuoco feature (stromboli isl.): morphologic characterization acta vulcanologica, 3, pp. 91-98. rosi m. (1980) the island of stromboli in: “the aeolian islands. an active volcanic arc in the mediterranean sea”. rend. soc. it. mineral. petrol., 36 (1), pp.345-368. t inti s., b ortolucci e. & r omagnoli c. (1999) – modeling a possibile holocenic landslide-induced tsunami at stromboli volcano, italy phys. chem. earth, 24, pp. 423-429. tranne c.a., calanchi n., lucchi f. & rossi p.l. (2000) geological sketch map of lipari (aeolian islands, italy) ed. dip. scienze della terra e geologicoambientali, università di bologna. 244 f. geremia & r. massoli-novelli imp.fioraso& manifestazioni carsiche nelle evaporiti messiniane del monferrato e della collina di torino (italia nord-occidentale): analisi dei meccanismi genetici nel quadro dell'evoluzione pliocenico-quaternaria del bacino terziario piemontese gianfranco fioraso1, erica bicchi2, andrea irace3 & paola boano2 1cnr istituto di geoscienze e georisorse, via accademia delle scienze 5, 10123 torino. e-mail: g.fioraso@csg.to.cnr.it 2collaboratore esterno del cnr istituto di geoscienze e georisorse, via accademia delle scienze 5, 10123 torino 3dipartimento di scienze della terra università di torino, via accademia delle scienze 5, 10123 torino riassunto: fioraso g. et al., manifestazioni carsiche nelle evaporiti messiniane del monferrato e della collina di torino (italia nordoccidentale): analisi dei meccanismi genetici nel quadro dell'evoluzione pliocenico-quaternaria del bacino terziario piemontese. it issn 0394-3356, 2004. la successione messiniana affiorante nel bacino terziario piemontese (btp) è interessata da diffusi fenomeni di dissoluzione che coinvolgono i blocchi gessosi, di dimensioni ettometriche-chilometriche, inglobati nella matrice marnoso-argillosa del complesso caotico della valle versa (ctv). la presenza nel monferrato settentrionale e nella collina di torino di numerose cave di gesso a cielo aperto e in sotterraneo, localizzate in contesti strutturali e a livelli stratigrafici differenti, ha fornito lo spunto per effettuare uno studio di dettaglio sulla distribuzione tridimensionale dei sistemi carsici, sulle caratteristiche morfologiche delle cavità e sul tipo di sedimenti di riempimento in essi presenti. le manifestazioni di dissoluzione epigee (camini a profilo cilindrico o conico a sviluppo verticale con diametro non superiore ai 5÷6 m) si localizzano nella prima decina di metri dei blocchi gessosi, al di sotto di una coltre di sedimenti impermeabili di spessore compreso tra i 4÷5 m e i 50 m. più in profondità la dissoluzione da luogo a condotti subverticali (con diametro inferiore a 3÷4 m) e cavità orizzontali a "soffitto piatto": queste ultime sono prodotte dal temporaneo stazionamento del livello di falda endocarsico e da concomitanti fenomeni di "stratificazione di densità" delle acque di percolazione che concentrano l'effetto dissolutivo nei settori marginali delle cavità. l'orientazione delle forme epigee e ipogee è inoltre sempre svincolata rispetto all'andamento locale della stratificazione degli intervalli gessosi del ctv. la dissoluzione è accompagnata da fenomeni di piping che consentono l'ingresso nei circuiti carsici dei prodotti della rielaborazione delle coltri di copertura e il loro trasferimento verso le parti più profonde e libere del reticolato ipogeo: l'infiltrazione dei sedimenti induce, in superficie, lo sviluppo di episodi di subsidenza (cover-subsidence sinkhole) e di sprofondamento (cover-collapse sinkhole) che coinvolgono per ampi tratti i versanti collinari modellati nel ctv. i tappi di sedimenti che occludono le cavità carsiche sono costituiti da: "brecce di collasso", prodotte dall'assestamento gravitativo delle coltri di copertura; "argille e silt massivi e laminati", riconducibili a episodi di decantazione in cavità sature; "sabbie massive e stratificate", veicolate da correnti trattive operanti all'interno dei circuiti carsici; "brecce di estrusione", generate da meccanismi di iniezione e spremitura dei sedimenti argillosi saturi d'acqua nelle parti più profonde e libere delle cavità ipogee. le analisi biostratigrafiche effettuate su 9 campioni di sedimenti prelevati all'interno di alcune cavità ipogee hanno evidenziato associazioni faunistiche rappresentative di un ampio intervallo temporale: burdigaliano (zona n5/6) zancleano (zona mpl4a) per la cava di montiglio, riferimento confermato dalla presenza di globorotalia puncticulata nel campione mnt-1 e di catapsydrax dissimilis, catapsydrax unicavus e globoquadrina dehischens in mnt-2; tortoniano (zona n17) zancleano (zona mpl2) per la cava di moncucco t.se, età confermata dalla presenza di globigerina quinqueloba in mc-13 e di globorotalia margaritae in mc-23; zancleano (zona mpl3) per grana m.to, età confermata dalla presenza di globorotalia margaritae e di globorotalia puncticulata in grn-1. i campioni mnc-1, mnc-2 e mnc-3 provenienti dalla cava di moncalvo sono risultati sterili. le associazioni individuate rispecchiano sempre l'assetto lito-strutturale locale della successione cenozoica presente al tetto delle bancate gessose carsificate. le caratteristiche dei sistemi carsici (assetto tridimensionale, dimensione e gerarchizzazione delle cavità, spessore del volume gessoso coinvolto) sono controllate dall'entità dell'esumazione, e quindi dal grado di dissezione da parte del reticolato idrografico, del ctv: quest'ultimo è caratterizzato nell'insieme da un assetto monoclinalico immergente di 2÷5° verso le aree depocentrali di asti e alessandria, che ha consentito di differenziare procedendo da nord verso sud: un "carso inciso" (entrenched karst), nel quale i blocchi selenitici sono profondamente dissecati dal reticolo idrografico (es. settori di murisengo e moncucco t.se). il gradiente idraulico è in questo caso maggiore rispetto agli adiacenti settori del complesso carsico monferrino e i fenomeni di dissoluzione coinvolgono l’intera potenza carsificabile dei gessi; un "carso subgiacente" (subjacent karst), nel quale l'intervallo gessoso è solo parzialmente inciso e drenato dal reticolato idrografico (es. settori di grana m.to e gessi di moncalvo) e la dissoluzione appare ben sviluppata unicamente al di sopra del livello di base locale; un "carso profondo" (deep-seated karst), nel quale i blocchi gessosi, posti al di sotto dei fondovalle, sono confinati e sigillati al di sotto dalla successione pliocenica monferrina (argille azzurre, sabbie di asti e villafranchiano auct.). le sporadiche manifestazione carsiche presenti sono in questo caso legate alla risalita di acque profonde lungo fasce di deformazione tettonica. la speleogenesi nei gessi è influenzata dalla presenza di potenti coltri di copertura, costituite dalla matrice del ctv e dalla sovrastante successione pliocenico-quaternaria, contraddistinte da bassi coefficienti di permeabilità che ostacolano il deflusso delle acque di percolazione. una volta raggiunta l'interfaccia con il gesso, il controllo sulla circolazione endocarsica è svolto dall'intreccio di 3 principali sistemi di faglie e fratture orientati in direzione e-w, ne-sw e n-s. queste discontinuità costituiscono le uniche vie di deflusso delle acque in un mezzo altrimenti caratterizzato da bassi valori di porosità primaria compresi tra il 4 e l'8% del volume roccioso. le faglie interrompono inoltre la continuità degli interstrati pelitico-bituminosi che imporrebbero altrimenti la compartimentazione dei circuiti idrocarsici all'interno delle bancate gessose. la variazione dei parametri morfometrici (diametro e lunghezza) dei condotti carsici e del loro grado di interconnessione idraulica conil quaternario italian journal of quaternary sciences 17(2/2), 2004, 453-476 454 g. fioraso et al. fermano che il picco dissolutivo si manifesta nei primi 15÷20 m dei corpi gessosi: l'aggressività dell'acqua, infatti, diminuisce in breve tempo e a breve distanza dal punto di ingresso nel sistema carsico, grazie all'elevata velocità di saturazione in caso4 · 2h2o della soluzione in rapporto alla velocità di deflusso. il limitato numero di condotti ipogei intercettati dai fronti di coltivazione spinti al di sotto dei fondovalle (es. cave di gessi di moncalvo, murisengo e montiglio) conferma inoltre l'arresto della dissoluzione in prossimità della superficie della falda freatica, che a sua volta si raccorda con il livello di base locale: le basse velocità di deflusso che contraddistinguono la zona satura rispetto a quella areata non consentono un rapido ricambio delle acque, inibendo l'azione dissolutiva che in tal modo non può svilupparsi nella sua completezza. l'analisi dei rapporti che intercorrono tra l'orientazione degli intervalli evaporitici e la vergenza delle forme dissolutive evidenzia chiaramente la sequenzialità del fenomeno carsico rispetto all'assetto stratigrafico assunto localmente dal ctv. inoltre la presenza di cavità a "soffitto piatto" altimetricamente correlabili con lembi di depositi fluviali terrazzati (con indice di colore massimo pari a 5÷7,5 yr) conservati a varie quote lungo le dorsali collinari del monferrato, avvalora l'ipotesi secondo cui queste morfologie endocarsiche materializzerebbero delle paleo-superfici freatiche originariamente in raccordo con antichi livelli di base. ciò consente di ipotizzare, quanto meno nei settori di maggior maturità dei sistemi carsici (es. murisengo e moncucco t.se), un’età delle forme dissolutive compresa tra la parte superiore del pleistocene medio e l'attuale. i sistemi carsici impostati nei gessi messiniani del monferrato e della collina di torino e i depositi in essi ospitati rappresentano il prodotto di concomitanti fenomeni di dissoluzione e sedimentazione polifasici e policronologici, sviluppati in risposta alle continue variazioni indotte sull'assetto morfologico superficiale dall'esumazione del ctv. quest'ultima è l'espressione della deformazione che ha determinato il sovrascorrimento verso nord della successione cenozoica del btp sull'avanfossa padana: al procedere dell'esumazione si contrappone la migrazione relativa del fronte di dissoluzione, che viene in tal modo a collocarsi in posizioni via via più prossime alla base dell'intervallo evaporitico. abstract: fioraso g. et al., karst phenomena in messinian succession of monferrato and torino hill (north-western italy): speleogenetic mechanism and interaction with pliocenic to quaternary evolution of tertiary piedmont basin. it issn 0394-3356, 2004. in tertiary piedmont basin (tpb) widespread karst phenomena involved messinian gypsum blocks (hectometric to kilometric in extention) cropping out within the clayey matrix of the valle versa chaotic complex (ctv). the presence of some gypsum quarries in northern monferrato area and in torino hill (whether opencast or underground) allowed the investigation of speleogenetic phenomena in different structural and stratigraphic contexts. this study has been carried out in order to detect three-dimensional array of karst systems, morphological characteristics of dissolution cavities and sedimentological analysis of karst infill deposits. moreover, it has been possible to reconstruct some of karst evolutionary stages related to the pliocenic to quaternary exumation of tpb. cilindrical or cone-shaped subvertical pipes less than 5÷6 m in diameter which characterize epigean dissolution morphology are located within upper 10 m of evaporitic rocks, below an impermeable sedimentary cover with thickness ranging between 4÷5 m and 50 m. in depth, dissolution make up subvertical pipes (less than 3÷4 m in diameter) connected with horizontal caves with typical "flat ceilings" and inclined (15÷45°) lateral facets. these forms are caused by a standing of water table combined with water chemical stratification phenomena: local small differences in water density promote natural convection currents inside gypsum caves which enable most pronunciated marginal dissolution by uppermost aggressive layers of water. orientation of epigean and hypogean morphology is geometrically unrelated in respect to the bedding of ctv gypsum layers. gypsum dissolution combine with suffosion processes so that transfer of insoluble sediments of the overlying clayey sequence inside empty karst cavities is enabled. this result in a gradual subsidence of the topographic surface or in a sudden collapse of the overburden, with development of cover-subsidence and cover-collapse sinkhole respectively, depending on granular composition and thickness of the coverbeds. such features are well developed all over the outcropping area of ctv. epikarst depressions and endokarst caves are filled with intricate sequences of deposits, made up of at least 4 sedimentary facies: a) "collapse breccia", developed by gravitational sinking of sedimentary coverbed; b) "massive or laminated silt and clay", due to sediments settling in water-filled karst features; c) "massive or laminated sands", transported by percolating water inside karst system; d) "extrusion breccia", generated by injection and squeezing of water-saturated clayey sediments along deepen free portions of caves. distribution of sedimentary facies within karst network is highly variable in both vertical and horizontal directions. biostratigraphical analysis carried out on 9 samples collected inside few hypogean cavities allows the detection of rich faunal assemblages covering a wide chronological interval: burdigalian (n5/6 zone) zanclean (mpl4a zone) for samples collected in montiglio quarry, in which are present globorotalia puncticulata in mnt-1 and catapsydrax dissimilis, catapsydrax unicavus and globoquadrina dehischens in mnt-2; tortonian (n17 zone) zanclean (mpl2 zone) for samples collected in moncucco t.se quarry, age confirmed by the presence of globigerina quinqueloba in mc-13 and of globorotalia margaritae in mc-23; zanclean (mpl3 zone) for samples grn-1 collected in grana m.to quarry, confirmed by the presence of globorotalia margaritae and globorotalia puncticulata. on the contrary, sediments collected on moncalvo quarry (samples mnc-1, mnc-2 and mnc-3) are completely devoid of microfaunal remains. differences in faunal assemblages from one site to another are due to the specific and local litho-structural arrangement of cenozoic succession resting above the gypsum interval. three-dimentional array of cave network, size and interconnection magnitude of hypogean conduits and thickness of gypsum volume involved in dissolution processes are controlled by exumation rate of ctv and consequently by superficial fluvial erosion. from northern monferrato to torino hill, the messinian succession has a monoclinalic configuration dipping of 2÷5° to the depocentral areas of asti and alessandria, so that it is possible to distinguish, from north to south, three types of intrastratal karst: "entrenched karst", with gypsum completely dissected by fluvial erosion (i.e. murisengo and moncucco t.se areas). hydraulic gradient is greater than in other sectors of karst complex and dissolution operate across the whole thickness of the evaporite formation; "subjacent karst", where gypsum is only partially dissected by superficial drainage system (i.e. grana m.to and gessi di moncalvo areas). dissolution phenomena are well developed inside gypsum rocks only above hydrological base-level; "deep-seated karst", where gypsum sequence is buried and hydrologically confined below a thick post-messinian sedimentary cover, represented by pliocenic argille azzurre and sabbie di asti formations and by pliocenic to quaternary villafranchian complex. due to the thickness of the overburden (> 40÷50 m), deep-seated karst is devoid of any surface expression. locally dissolution phenomena are linked to the rising of deep water along fault zones. development of gypsum dissolution is controlled by lithology and thickness of the coverbeds, generally characterized by low permeability (particularly the clayey matrix of ctv and the argille azzurre formation), that slow down the trasmission of seepage water across the overburden. just in contact with gypsum, water circulation depends on the pattern distribution of at least 3 fault and fracture systems with e-w, ne-sw and n-s directions. such discontiniuties assumed the major role in determining the initial flow path inside a gypsum, otherwise characterised by low percentage (4÷8%) of primary porosity. moreover, fault systems intersect and displace the impermeable bituminous inter-beds (with tickness < 3 m) controlling water circulation between adjacent gypsum intervals. tipology and dimensions (cross-section diameter and length) of karst features combined with analisys of cave pattern prove that the highest dissolution rate occur within the first 15÷20 m below gypsum-coverbed interface: saturation index of solution in respect to caso4 · 2h2o rapidly increase after the entrance inside karst system. moreover, the restricted number of pipes and horizontal caves intercepted by underground mining exploitation below the base-level (i.e. gessi di moncalvo, murisengo and montiglio quarries) con1. introduzione i sistemi carsici rappresentano eccellenti punti chiave per la ricostruzione della storia morfo-evolutiva di un rilievo: in essi, infatti, sono spesso chiaramente conservate le tracce, in forma di cavità di dissoluzione e di depositi di riempimento chemio-clastici, che ne attestano alcune delle infinite tappe evolutive (salomon, 1999; nicod, 2002). inoltre, la particolarità dei sistemi carsici risiede nel poter adeguare più o meno rapidamente la propria fisionomia alle variazioni morfologiche indotte sul territorio dalla mobilità tettonica e dai processi erosivo-deposizionali che avvengono in superficie. la distribuzione tridimensionale delle forme di dissoluzione e dei depositi in esse contenuti costituisce pertanto un ideale registro naturale della successione di eventi che scandiscono l'evoluzione di un rilievo: questo ruolo è favorito dall'elevata conservatività dell'ambiente carsico, legata da un lato alle particolari modalità di infiltrazione e di deflusso ipogeo delle acque di precipitazione, dall'altro all'assenza di un reticolato idrografico di superficie in grado di operare con sufficiente incisività lo smantellamento del rilievo. quanto sopra esposto ben si adatta non solo ai sistemi carsici modellati nei comuni substrati carbonatici, ma anche a quelli, meno diffusi, sviluppati nelle successioni evaporitiche. la carsogenesi nei gessi, tuttavia, pur dando luogo a manifestazioni in prima approssimazione confrontabili con quelle presenti nelle rocce carbonatiche (macaluso et al., 2001; johnson, 2002), è caratterizzata da un'elevata velocità della cinetica dissolutiva: ciò conferisce una minore inerzia del carso gessoso nella risposta offerta alla mobilità tettonica e una sensibile riduzione dei tempi di reazione del sistema carsico alle variazioni morfologiche del rilievo. la rapidità evolutiva costituisce pertanto il principale carattere distintivo dei processi di dissoluzione sviluppati nei gessi, dovuta all'estrema facilità con cui queste rocce possono essere disciolte: in acqua distillata a 20°c e alla pressione di 1 atm, il gesso risulta infatti 183 volte più solubile della calcite (jakucs, 1977), cosicché la dissoluzione può operare con una velocità di due ordini di grandezza più elevata rispetto a quanto mediamente avviene in rocce calcaree (eck & redfield, 1965). il territorio piemontese si caratterizza per la fre455manifestazioni carsiche nelle evaporiti ... quente presenza di gessi, distribuiti in due ben distinti contesti geologici: un primo gruppo di circoscritte masse gessose di età triassica sottolinea alcuni dei principali contatti tettonici e orizzonti di scollamento dell'arco alpino occidentale; un secondo e più cospicuo gruppo affiora nella successione messiniana del bacino terziario piemontese (btp) (fig. 1a), nell’ambito della quale da lungo tempo sono state riconosciute manifestazioni carsiche (sacco, 1889-1890; 1925; marinelli, 1917). i rilievi recentemente condotti per la realizzazione del foglio 157, "trino", alla scala 1:50.000 del progetto carg (dela pierre et al., 2003b) e quelli attualmente in corso di svolgimento nel contiguo foglio 156, "torino est", hanno consentito di delineare con maggior precisione la distribuzione, l’entità e la tipologia di questi fenomeni: da un lato è emersa la notevole frequenza degli episodi di dissoluzione sviluppati a spese degli intervalli gessosi, dall'altro è stata evidenziata la complessità dei sistemi carsici dovuta al concomitante sviluppo di manifestazioni para-carsiche (piping) che coinvolgono estesamente le sovrastanti coltri terrigene di copertura (fioraso & boano, 2002): queste ultime comprendono sia i termini della successione marina post-evaporitica, sia i depositi quaternari continentali (coltri eluvio-colluviali, depositi fluviali e accumuli di frana). in questo contesto sono state effettuate nuove e più dettagliate indagini, finalizzate a chiarire i rapporti intercorrenti tra lo sviluppo del carsismo nell'ambito della successione messiniana e l’evoluzione post-miocenica del btp. l'analisi è stata condotta attraverso la sistematica raccolta di informazioni di carattere morfologico, stratigrafico e micropaleontologico riguardanti le cavità e i relativi depositi di riempimento. il lavoro è stato agevolato dalla presenza, nelle aree del monferrato e della collina di torino, di numerosi fronti di coltivazione a cielo aperto e di cavità minerarie sotterranee che in più punti hanno intercettato il reticolato carsico epigeo e ipogeo. le cave, realizzate per lo sfruttamento dei banchi gessosi, sono distribuite in una fascia compresa tra gli abitati di grana m.to, a est, e moncucco t.se a ovest (fig. 1). tale opportunità ha consentito di definire i limiti e l'assetto tridimensionale dei circuiti carsici e di analizzare i meccanismi speleogenetici a livelli stratigrafici e in contesti strutturali alquanto differenti. in tal modo è stato possibile tracciare un dettagliato quadro firm that dissolution rates drastically reduce in proximity of the water table, the last one fitting with local base-level: flow velocities in phreatic conditions are lower in comparison with those of vadose zone, so that water is not allowed to have a rapid exchange and speleogenesis does not fully develop inside evapotitic rocks. spatial orientation of dissolution pipes diverging from gypsum bedding clearly demonstrate the sequentiality of dissolution phenomena in comparison to litho-structural array of ctv. locally "flat ceilings" in horizontal caves are altimetrically correlable with terraced fluvial deposits (with highest color index of 5÷7,5 yr) preserved along valley sides of monferrato and torino hill: such features materialize paleo-phreatic surfaces originally related to old fluvial base-levels. available data point out a late middle pleistocene to olocene age for the karst systems characterized by highest evolution, like in murisengo and moncucco t.se areas. gypsum karst and related deposits in tpb, representing the products of polyphasic and polychronologic dissolution phenomena, developed in responce to morphological change induced by differential exumation of ctv. uplifting of messinian succession is linked to the tectonic deformation due to the northern thrusting movements of the tpb succession over padanian foredeep: the ongoing exumation is accompained by progressive downward migration of a dissolution boundary (that gradually comes close to and finally intersects the base of evaporitic succession) and by an evolutionary sequence of karst types providing the transition from deep-seated to entrenched karst. parole chiave: carsismo, suffosione, gesso, messiniano, collina di torino, monferrato. keywords: : karst, piping, gypsum, messinian, torino hill, monferrato. 456 g. fioraso et al. fig. 1 a) inquadramento geologico dell'area di studio. 1: catena alpina (al); 2: catena appenninica (ap); 3: falde liguri (fl); 4: bacini sedimentari paleogenico-neogenici su substrato alpino (ct = collina di torino; lg = langhe) e appenninico (mn = monferrato); 4a: successione messiniana (m); 5: sedimenti pliocenico-quaternari; 6: fronti di sovrascorrimento; 7: cava di moncucco t.se. b) schema geologico del monferrato settentrionale (da dela pierre et al., 2003b, modificato). daq: depositi alluvionali quaternari; smd: sabbie di ferrere, silt di s. martino e unità di morialdo ("villafranchiano" auct.); ast: sabbie di asti; faa: argille azzurre; ctv: complesso caotico della valle versa ("formazione gessoso-solfifera" auct.); saf: marne di s. agata fossili; min: marne di mincengo; cto: areniti di tonengo; pdc: pietra da cantoni; ama: arenarie di moransengo; mpi: marne a pteropodi inferiori; ant: formazione di antognola; cad: formazione di cardona; mmp: marne di monte piano; cmo: formazione di casale monferrato; ccp: complesso caotico di la pietra; gs: principali affioramenti di gesso. a: faglie; b: faglie incerte o sepolte; c: traccia delle sezioni geologiche; d e: cave attive e inattive (1 = banengo; 2 = montiglio; 3 = corziagno; 4 = bricco; 5 = murisengo; 6 = pirenta; 7 = borghi; 8 = gessi di moncalvo; 9 = verginetto; 10 = c.ne pietra; 11 = grana m.to; 12 = madonnina); f: sorgenti cloruroe solfato-calciche (s1 = pirenta di murisengo; s2 = calliano); g: sorgenti bicarbonato-calciche e magnesiache (s3 = capriglio; s4 = lussello; s5 = alfiano natta; s6 = ponzano); h: sorgenti cloruro-sodiche (s7 = passerano-marmorito); i: principali lembi di depositi fluviali terrazzati. a) geological sketch of the tertiary piedmont basin. 1: alpine thrust belt (al); 2: apenninic thrust belt (ap); 3: ligurian nappes (fl); 4: alps-related (ct = torino hill; lg = langhe) and apennines-related (mn = monferrato) paleogenic to neogenic sedimentary domains; 4a: messinian succession (m); 5: pliocenic to quaternary sediments; 6: apenninic thrusts; 7: moncucco t.se quarry. b) geological sketch of the northern monferrato area (from dela pierre et al., 2003b, modified). daq: quaternary alluvial sediments; smd: ferrere sands, s. martino silts and morialdo unit ("villafranchiano" auct.); ast: asti sands; faa: argille azzurre; ctv: valle versa chaotic complex ("gessoso-solfifera formation" auct.); saf: s. agata fossili marls; min: mincengo marls; cto: tonengo arenites; pdc: pietra da cantoni; ama: moransengo sandstones; mpi: pteropodi marls; ant: antognola formation; cad: cardona formation; mmp: monte piano marls; cmo: casale monferrato formation; ccp: la pietra chaotic complex; gs: main gypsum bodies. a: faults; b: uncertain or buried faults; c: traces of geological cross-sections; d e: active and inactive quarry (1 = banengo; 2 = montiglio; 3 = corziagno; 4 = bricco; 5 = murisengo; 6 = pirenta; 7 = borghi; 8 = gessi di moncalvo; 9 = verginetto; 10 = c.ne pietra; 11 = grana m.to; 12 = madonnina); f: cl / so4 2/ ca2+ springs (s1 = pirenta di murisengo; s2 = calliano); g: hco3 / ca2+ / mg2+ springs (s3 = capriglio; s4 = lussello; s5 = alfiano natta; s6 = ponzano); h: cl / na+ springs (s7 = passerano-marmorito); i: fluvial terraces. 457 dei fenomeni dissolutivi e dei concomitanti episodi di sedimentazione, consentendo inoltre di delineare un modello evolutivo del fenomeno carsico in accordo con il contesto idrologico e idrogeologico locale. l'analisi integrata dei dati di superficie e di sottosuolo ha infine permesso di ricostruire alcune delle tappe che hanno scandito l'evoluzione del complesso carsico messiniano e accompagnato le ultime e più recenti fasi di strutturazione dei rilievi del monferrato settentrionale e della collina di torino. 2. assetto litostratigrafico e morfologico i depositi messiniani affioranti lungo il margine settentrionale del btp costituiscono una fascia pressoché continua, orientata all’incirca in direzione e-w, lungo i settori meridionali delle unità del monferrato a est e della collina di torino a ovest (rispettivamente mn e ct in fig. 1a). questi sedimenti, compresi nella formazione gessoso-solfifera (bonsignore et al., 1969), sono stati classicamente descritti come un intervallo stratigrafico costituito da marne argillose contenenti lenti e corpi eterometrici di gesso selenitico e di calcari vacuolari (“calcari a cellette”). studi di dettaglio effettuati da sturani (1973) nel settore sw del btp hanno consentito di individuare tre distinti intervalli stratigrafici: un intervallo inferiore “pre-evaporitico”, costituito da sedimenti marini profondi deposti in normali condizioni di salinità e corrispondenti al “tripoli” della sicilia; un intervallo intermedio “evaporitico”, rappresentato da depositi lagunari, introdotto da sottili livelli calcarei (“calcare di base”) e costituito da gesso microcristallino laminato (gesso balatino); un intervallo superiore “post-evaporitico”, costituito da sedimenti alluvionali, palustri e lacustri (“strati a congerie”), confrontabili con le facies "lago-mare" riconosciute in gran parte dell’area mediterranea (rouchy et al., 2001) e descritti e cartografati nel btp meridionale come conglomerati di cassano-spinola (boni & casnedi, 1970). la successione individuata da sturani rappresenta tuttavia un’eccezione all’interno del btp: infatti, al margine se del btp, la gessoso-solfifera è interamente costituita da masse di gesso disarticolate e da livelli, riconducibili a fenomeni di debris-flow, costituiti da cristalli di gesso immersi in una matrice pelitica con zolle di peliti varvate (ghibaudo et al., 1985). anche i rilievi recentemente effettuati nel monferrato settentrionale per la realizzazione del foglio 157 “trino” (dela pierre et al., 2003b) hanno confermato che i depositi messiniani sono in realtà costituiti da un intervallo caotico di sedimenti, informalmente denominato “complesso caotico della valle versa” (ctv) (dela pierre et al., 2003a). i depositi del ctv poggiano in discordanza su sedimenti marini di età compresa tra l’oligocene e il tortoniano (formazione di cardona, areniti di tonengo, marne di mincengo e marne di s. agata fossili) e sono seguiti, sempre in discordanza, dai depositi emipelagici pliocenici della formazione delle argille azzurre, costituita da membri siltoso-argillosi, argillosi e siltoso-sabbiosi (fig. 1b). il ctv è caratterizzato da notevoli variazioni di potenza (con valori massimi pari a 100÷150 m) ed è composto da blocchi di dimensioni chilometriche/decametriche inglobati in una matrice argillosa. i blocchi sono costituiti da calciruditi e calcareniti fossilifere, indicativi di una sedimentazione carbonatica in acque poco profonde, del messiniano inferiore pre-evaporitico, da alternanze di gessi selenitici, peliti e calcari vacuolari riferibili alla fase evaporitica, e da conglomerati poligenici post-evaporitici. sono inoltre presenti blocchi di calcari micritici fortemente cementati, con modelli interni di lucinidi, e brecce carbonatiche, interpretabili come calcari metano-derivati (clari et al., 1994). la matrice del ctv è rappresentata, almeno localmente, da mud-breccias nelle quali è stato riscontrato un notevole mixing delle associazioni a microfossili, testimoniato dalla compresenza di forme riferibili al miocene, all’oligocene e all’eocene (dela pierre et al., 2002). i blocchi di dimensioni maggiori (chilometriche/ ettometriche) sono costituiti da un’alternanza ciclica di banchi di gesso selenitico, potenti da qualche metro fino a un massimo di 30 m, e di livelli pelitici bituminosi di spessore compreso tra pochi decimetri fino a un massimo di 3 m (es. gessi di moncalvo). ogni coppia pelite-gesso costituisce un singolo ciclo evaporitico (vai & ricci lucchi, 1977) e testimonia il graduale passaggio a condizioni iperaline, favorevoli alla precipitazione della selenite che si presenta con la caratteristica geminazione a “coda di rondine”. l’evidente diminuzione di taglia dei cristalli (da decimetrica a millimetrica) verso il tetto dei banchi di gesso riflette la progressiva saturazione dell'originaria salamoia: ciò, tuttavia, non costituisce una regola, potendosi talvolta osservare una gradazione inversa dei cristalli. a vari livelli stratigrafici sono inoltre presenti intercalazioni di corpi gessoruditici e gessarenitici che testimoniano fenomeni erosionali, a pelo d’acqua o subaerei, a spese dei depositi solfatici primari. la potenza complessiva delle bancate gessose è di poco superiore ai 100÷120 m (bosticco et al., 1992; bosticco & marini, 1995). la giacitura della stratificazione è piuttosto irregolare, variando da suborizzontale (es. grana m.to; fig. 2, sez. a-a') o poco inclinata (10° verso se a moncalvo; fig. 2, sez. b-b'), fino a sensibilmente inclinata (50° verso sse) come a murisengo. i gessi del monferrato sono attraversati da tre sistemi di strutture disgiuntive: un sistema e-w, visibile in quasi tutti i fronti di cava, costituito da faglie e fratture, il più delle volte immergenti a sud, con inclinazione compresa tra 50° e 90° e direzione variabile da n70° a n105°; un sistema ne-sw, rappresentato da faglie immergenti sia a se che a nw con inclinazione compresa tra 60° e 90° e direzione variabile da n30° a n65°; un sistema n-s, riscontrabile unicamente nel settore compreso tra murisengo e montiglio, costituito da strutture ad andamento subverticale. anche nella collina di torino l'intervallo messiniano, sempre attribuito al ctv (polino, 2002; irace et al., 2002), è in gran parte caratterizzato da un assetto caotico, espresso dalla distribuzione casuale di blocchi carbonatici e gessosi all'interno di una matrice marnoso-argillosa poco coerente e male esposta. i blocchi carbonatici, da decimetrici a metrici, risultano del tutto confrontabili con quelli presenti nel monferrato. i blocchi di gesso, con l'esclusione della sola area di moncucco t.se, sono di dimensioni assai ridotte e il più delle volte rappresentati da clasti di taglia decimetrica dispersi nella matrice. manifestazioni carsiche nelle evaporiti ... 458 nella collina di torino la superficie basale del ctv corrisponde a una discordanza che comporta la diretta sovrapposizione del complesso sulle marne di mincengo e di s. agata fossili. tuttavia, a differenza di quanto osservato nel monferrato, tale superficie risulta modellata meno profondamente nei termini più antichi ed è ancora possibile osservare (anche se solo localmente) la porzione sommitale delle marne di s. agata fossili, riferibile al messiniano inferiore pre-evaporitico. nella cava di moncucco t.se è visibile la tri-partizione della successione messiniana proposta da sturani (1973), ma in un contesto tettonico che ha in gran parte obliterato gli originari rapporti stratigrafici (fig. 2, sez. d-d'): i depositi pre-evaporitici del messiniano inferiore (marne di s. agata fossili) sono infatti intensamente deformati e giustapposti all’unico corpo gessoso affiorante nella collina di torino tramite due sistemi di faglie transpressive: il primo, a direzione media n170÷180°, immerge di 30÷60° verso ene; il secondo, a direzione n20÷30°, è costituito da faglie coniugate con inclinazioni variabili da 50÷60° verso wnw a 20° verso sw, che descrivono in sezione una struttura "a fiore" asimmetrica verso se (festa et al., 2002; polino, 2002). la successione evaporitica si presenta inclinata di 45÷50° verso ssw ed è costituita da bancate di gesso selenitico potenti da 10 a 30 m alternate a livelli pelitici decimetrici (irace et al., 2002). i contatti tettonici sono progressivamente sigillati da marne argillose e da mud-breccias (inglobanti blocchi di gessi selenitici, di gessoruditi, di calcari vacuolari e brecciati), nonché da peliti beige passanti a marne siltose verdastre, contenenti associazioni fossilifere tipiche di acque salmastre (limnocardium sp., dreissena sp., melanopsis sp.), che consentono un riferimento al messiniano post-evaporitico (facies “lago-mare”). infine segue, in discordanza, la formazione delle argille azzurre, di età pliocenica inferiore. i dati illustrati consentono quindi di delineare un quadro piuttosto articolato della successione messiniana: nel monferrato settentrionale il messiniano è rappresentato da un intervallo caotico di sedimenti (ctv) che ingloba depositi preevaporitici, evaporitici e post-evag. fioraso et al. fig. 2 sezioni geologiche e localizzazione dei punti di campionamento dei sedimenti carsici. per l'ubicazione delle sezioni cfr. fig. 1. ctv: complesso caotico della valle versa; saf: marne di s. agata fossili; daq: depositi alluvionali quaternari; faa/9: argille azzurre membro siltoso-argilloso; faa/10: argille azzurre membro argilloso; ast/2: sabbie di asti membro sabbioso; 1: gesso; 2: terreno di riporto; 3: cavità carsiche; 4: faglie; 5: sigla del campione; 6: livello di coltivazione. geological cross-sections and localization of samples collected inside karst cavities. traces of cross-sections are shown in fig. 1. ctv: valle versa chaotic complex; saf: s. agata fossili marls; daq: quaternary alluvial sediments; faa/9: argille azzurre silty-clayey member; faa/10: argille azzurre clayey member; ast/2: asti sands sandy member; 1: gypsum; 2: waste disposal; 3: karst cavities; 4: faults; 5: sample number; 6: mining drift. poritici; nella collina di torino l’intervallo post-evaporitico, costituito dai depositi di lago-mare, è invece solo in parte caotico e sembra sigillare un importante evento deformativo intra-messiniano. in entrambi i settori investigati l'assetto del ctv è l'effetto della combinazione degli eventi sedimentari connessi alla crisi di salinità messiniana (hsü et al., 1973) e dei fenomeni tettonici sviluppatisi a scala regionale (pieri & groppi, 1981; gelati et al., 1987; piana, 2000; roveri et al., 2001; 2003). il fatto che la successione messiniana del monferrato e della collina di torino sia in gran parte costituita da isolati lembi risedimentati di evaporiti primarie, attualmente in giacitura secondaria, implica infatti una disarticolazione dell'originaria successione che consente di riferire il fenomeno di "caoticizzazione" all’intervallo post-evaporitico. per la genesi del ctv è stato ipotizzato l'intervento di collassi gravitativi a scala regionale guidati dalla tettonica e la concomitante risalita diapirica di sedimenti fini non consolidati e permeati da fluidi (dela pierre et al., 2002; 2003a). dal punto di vista morfologico, l'area di affioramento del ctv è contraddistinta da rilievi collinari poco acclivi che si elevano a non più di 300÷350 m s.l.m. le dorsali spartiacque hanno un profilo trasversale convesso, regolare e simmetrico e si raccordano ai piatti e ampi fondovalle tramite spessori più o meno consistenti di prodotti colluviali. il fondo delle incisioni vallive è costituito da coltri di depositi fluviali siltoso-sabbiosi, con intercalazioni ghiaiose e sabbiose, di esiguo spessore ma che localmente possono raggiungere valori di 6÷8 m. il profilo longitudinale delle dorsali collinari è interrotto da rotture di pendenza che sottendono superfici subpianeggianti di modellamento fluviale, sulle quali sono conservati lembi di sedimenti siltoso-argillosi e siltoso-sabbiosi poco addensati e privi di stratificazione (alessio et al., 1982; carraro & valpreda, 1991; dela pierre et al., 2003a) (fig. 1b). lo spessore dei depositi non è mai elevato e comunque inferiore ai 3÷4 m. il grado di alterazione pedogenetica varia da 5÷7,5 yr per i depositi distribuiti sulle dorsali e nelle fasce altimetriche più elevate dei versanti a 7,5÷10 yr per quelli sospesi di pochi metri sugli attuali fondovalle. la configurazione delle superfici di appoggio basale di questi sedimenti appare piuttosto complessa e articolata: i depositi sono infatti conservati in forma di lembi subpianeggianti, sospesi fino ad oltre un centinaio di metri sui fondovalle, in ampie depressioni allungate ad andamento curvilineo e, talvolta, in corrispondenza di selle ubicate nelle fasce più elevate dei versanti. tali superfici rappresentano il prodotto del graduale approfondimento erosivo del reticolato idrografico pregresso in risposta alla contemporanea e progressiva esumazione del rilievo (carraro & valpreda, 1991; dela pierre et al., 2003a) e che ha accompagnato, almeno fino al pliocene superiore (pieri & groppi, 1981; costa, 2003) e al pleistocene medio (enel, 1984), la strutturazione del thrust padano. i corsi d’acqua attuali, allineati in direzione n-s e ne-sw, mostrano nel complesso valori di gerarchizzazione e di densità di drenaggio piuttosto bassi. alla notevole ampiezza dei fondovalle, talvolta superiori al chilometro (es. valle versa e val cerrina), si contrappongono rii caratterizzati da deflussi con portate modeste o quasi nulle, con significativi rapporti di sottodimensionamento rispetto alla sezione dei solchi vallivi. 3. cavità di dissoluzione in tutte le masse di gesso affioranti o subaffioranti nei rilievi del monferrato e della collina di torino è stata rilevata la presenza di un ampio spettro di cavità di dissoluzione. analogamente a quanto accade nei terreni carbonatici, le cavità epigee, ospitate nella fascia pellicolare della successione evaporitica al contatto con le coltri di copertura, e quelle ipogee, individuate all’interno dei banchi gessosi, mostrano una distribuzione spaziale e caratteri morfo-dimensionali ben distinti in relazione ai differenti meccanismi speleogenetici ed evolutivi che hanno operato e operano nei diversi punti del sistema carsico (fig. 3). le forme di dissoluzione sviluppate nella “zona di assorbimento” dei sistemi carsici si concentrano nei primi metri della successione evaporitica: si tratta di cavità cilindriche o imbutiformi ("camini") a sviluppo subverticale, aventi un'altezza non superiore ai 6÷10 m e un'orientazione dell'asse sempre svincolata dall'andamento locale della stratificazione (fig. 4). le cavità hanno una sezione trasversale subcircolare o subellittica, con diametro compreso tra pochi centimetri e un massimo di 5÷6 m; spesso la sezione presenta un graduale restringimento verso il basso che dà luogo a un profilo longitudinale marcatamente conico. le cavità impostate lungo piani o zone di faglia mostrano invece sezioni irregolari e allungate parallelamente alle discontinuità tettoniche. le pareti delle cavità epigee, con superfici di corrosione regolari e prive di asperità, in taluni casi sono solcate da scanalature di piccolo diametro (5÷10 cm) ad andamento longitudinale. talvolta il numero di cavità per unità di superficie è così elevato da generare frequenti rapporti di interferenza, coalescenza e compenetrazione delle diverse forme carsiche: la configurazione dell'interfaccia gesso-coperture risulta in tal modo estremamente irregolare (“hummocky morphology”) e contraddistinta da culminazioni gessose alternate a depressioni con profondità non superiori ai 10 m (fig. 3). nella “zona di percolazione”, e in palese connessione con le forme epicarsiche, è presente un reticolo di condotti più o meno irregolari e scarsamente ramificati, con asse da molto inclinato (65÷80°) a verticale e uno sviluppo longitudinale accertato di alcune decine di metri (20÷30 m) (fig. 3 e 5). la sezione trasversale delle cavità è sensibilmente più irregolare rispetto alle corrispondenti forme epigee, sebbene non sia infrequente osservare condotti con profilo subcircolare o subellittico; anche le dimensioni variano considerevolmente, con diametri non superiori ai 3÷4 m e la presenza di repentini restringimenti di sezione o di vere e proprie strozzature. in alcuni casi i condotti immettono in cavità a sviluppo orizzontale contraddistinte da “soffitti di dissoluzione” perfettamente piatti e da pareti ad acclività variabile: 5÷15° nel caso di cavità con profilo piano-concavo (es. cava di murisengo), 35÷45° nel caso di cavità con profilo trapezoidale rovescio (es. cava di montiglio) (rispettivamente c1 e c2 in fig. 3). la loro altezza è compresa tra 3÷5 cm e un massimo di un metro, mentre in pianta si estendono per non più di una decina di metri. talvolta si rinvengono isolate all'interno della roccia; più frequentemente appaiono raggruppate e irregolarmente distribuite in senso verticale e comunque con un’orientazione sempre svincolata dall'andamento loca459manifestazioni carsiche nelle evaporiti ... le della stratificazione. queste cavità si sviluppano in ammassi selenitici sostanzialmente compatti e privi di disomogeneità tessiturali o di discontinuità (faglie, fratture o superfici di strato) tali da determinare significativi contrasti nei valori di permeabilità e solubilità della roccia. la loro presenza nell’ambito del sistema carsico può quindi essere spiegata chiamando in causa due distinti meccanismi genetici: il primo prevede l'esistenza di prolungati e ripetuti stazionamenti della superficie freatica, correlabili in superficie con episodi di terrazzamento fluviale, che consentirebbero alle acque sottosature in solfati di operare processi di dissoluzione a prevalente sviluppo orizzontale (warren et al., 1990); 460 g. fioraso et al. fig. 3 schema di distribuzione delle forme carsiche di dissoluzione e dei sedimenti di riempimento (non in scala). 1: brecce di collasso (facies “a"); 2: sabbie massive o stratificate (facies “b"); 3: argille e silt massivi o laminati (facies “c"); 4: brecce di estrusione (facies “d"); 5: coltri di copertura sovrastanti la successione evaporitica; 6: gesso; 7: faglie; 8: strutture da “iniezione”; a: camini di dissoluzione epigei; b: condotti di dissoluzione ipogei; c: cavità orizzontali; d: doline di collasso; e: doline di subsidenza. distribution sketch of karst features and filling deposits (not in scale). 1: collapse breccias (facies “a"); 2: bedded or massive sands (facies “b"); 3: massive or laminated silts and clays (facies “c"); 4: extrusion breccias (facies “d"); 5: post-evaporitic cover; 6: gypsum; 7: faults; 8: injection structures; a: epigean dissolution pipes; b: hypogean dissolution conduits; c: horizontal caves; d: cover-collapse sinkholes; e: cover-subsidence sinkholes. fig. 4 cavità di dissoluzione epicarsiche subverticali nella cava gessi di moncalvo. subvertical epikarst dissolution cavities in gessi di moncalvo quarry. nel secondo interverrebbero fenomeni di “stratificazione di densità” dell'acqua indotti dal diverso quantitativo di caso4 · 2h2o disciolto e, conseguentemente, al diverso peso specifico assunto dalla soluzione nei diversi punti delle cavità sature. secondo un modello evolutivo proposto da kempe (1972) e successivamente ripreso da klimchouk (1996b), il continuo apporto di fluidi sottosaturi provenienti dall'epicarso instaurerebbe un gradiente di densità dell'acqua contenuta all'interno delle cavità tale da consentire l’avvio di una lenta circolazione convettiva. lo strato d'acqua superficiale, più leggero e chimicamente più aggressivo nei confronti del gesso, consentirebbe una rapida solubilizzazione del gesso, concentrata nelle parti sommitali e periferiche delle cavità ("dissoluzione marginale"). arricchitasi in ioni solfato e raggiunti valori critici di concentrazione, la soluzione fluirebbe lungo le pareti dando luogo a correnti di densità caratterizzate da un potenziale dissolutivo decrescente procedendo verso la parte più depressa delle cavità. verrebbe in tal modo a configurarsi un sistema di celle convettive dinamicamente controllato dalle piccole e locali variazioni del chimismo (e quindi di densità) della soluzione presente nel circuito sotterraneo, in grado di modellare la volta delle cavità con un meccanismo di "spianamento" da dissoluzione. nel complesso, le cavità ipogee si estendono all’interno dei blocchi evaporitici per una profondità massima di circa 50÷60 m a partire dall’interfaccia gesso-coperture. la distribuzione delle forme carsiche ipogee è tuttavia piuttosto disomogenea: nelle cave sotterranee di montiglio, murisengo e moncalvo, in cui i livelli di coltivazione sono spinti ben al di sotto dei fondovalle, si osserva infatti un repentino diradamento delle cavità procedendo verso le parti più profonde delle masse gessose, cui si accompagna una diminuzione del loro diametro medio. il fronte di dissoluzione si arresta quasi completamente in prossimità o pochi metri al di sotto degli attuali fondovalle alluvionali. inoltre, il grado di interconnessione idraulica tra le diverse cavità appare, quanto meno a scala macroscopica, piuttosto basso, vista l'assenza di gallerie di trasferimento orizzontali anche di piccolo diametro. questi elementi concorrono nell'indicare una sensibile attenuazione dell'intensità dei processi di dissoluzione già a pochi metri dall'ingresso nel sistema carsico delle acque di percolazione: ciò confermerebbe l'esistenza di un limite fisico verticale allo sviluppo del carsismo, che risulterebbe confinato al di sopra del livello di base del sistema idrologico ipogeo, a sua volta in raccordo con il reticolato idrografico superficiale (klimchouk, 1996c). 4. fenomeni di subsidenza e collasso superficiali la rapidità evolutiva del carso gessoso trova riscontro anche in aree, come quelle del monferrato e della collina di torino, nelle quali l'elevato impatto antropico rappresentato dalle attività agricole causa spesso un intenso e costante rimodellamento del rilievo naturale. nonostante questa difficoltà è infatti possibile distinguere con chiarezza gli effetti indotti dal risentimento superficiale dei fenomeni di dissoluzione. tali effetti possono essere efficacemente descritti come combinazione di due distinti meccanismi genetici, che danno luogo ad altrettante e ben diverse morfologie (fig. 3): "doline di subsidenza" (subsidence doline, jennings, 1985; subsidence sink, arrington & lindquist, 1987; cover-subsidence sinkhole, tihansky, 1999). si tratta di depressioni chiuse o semiaperte, di forma subcircolare o ellittica, con un diametro massimo di circa 200 m (es. pirenta di murisengo) e una profondità non superiore ai 4÷5 m. la loro presenza è stata documentata in tutta l'area di affioramento del ctv (fioraso & boano, 2002); in alcuni settori, quale quello compreso tra gli abitati di cocconato e montiglio, la densità dei fenomeni è così elevata da conferire ai versanti una complessa quanto irregolare morfologia a dossi e depressioni. le doline di subsidenza si sviluppano a seguito della dissoluzione che avviene al contatto gesso-coperture, spesso accompagnata da fenomeni di piping (o “suffosione”, sensu castiglioni, 1986) che causano il trasferimento dei sedimenti siltoso-sabbiosi e argillosi superficiali all'interno dei circuiti carsici: le coltri di copertura, prive di un sufficiente grado di autoportanza, si assestano dando così luogo ad una localizzata subsidenza della superficie topografica (fig. 6). il fenomeno evolve gradualmente e in tempi relativamente brevi (se confrontati con analoghi fenomeni sviluppati in ambienti carbonatici), parallelamente al procedere della 461manifestazioni carsiche nelle evaporiti ... fig. 5 reticolo di condotti carsici ipogei messi in luce lungo i gradoni di coltivazione della cava di moncucco t.se. hypogean dissolution conduits exhumed along benches by exploitation activity in moncucco t.se quarry. dissoluzione nell'epicarso e all'ampliamento delle cavità e dei condotti ipogei; "doline di collasso" (subjacent karst collapse doline, jennings, 1985; arrington & lindquist, 1987; covercollapse sinkhole, tihansky, 1999). si tratta di depressioni chiuse subcircolari di diametro inferiore ai 15÷20 m e una profondità di alcuni metri, delimitate da scarpate molto acclivi o subverticali che configurano una sezione trasversale cilindrica o a imbuto. rispetto ai fenomeni di subsidenza, le doline di collasso presentano un più elevato rapporto profondità/diametro. i fenomeni di collasso, osservati e segnalati nei settori di montiglio, murisengo e guazzolo, sono causati dall'infiltrazione dei sedimenti di copertura siltoso-argillosi nei sottostanti condotti carsici ad opera di fenomeni di piping che inducono la formazione di cavità a cupola al contatto con i banchi di gesso (fig. 6): il continuo e graduale distacco di materiale provoca la migrazione verso l'alto del tetto della cavità e l'assottigliamento della volta che permane in condizioni di stabilità fintanto che le sollecitazioni, ridistribuite nell'intorno del vuoto secondo uno schema "ad arco", non superano la resistenza della calotta. oltrepassato tale limite la volta, non più in grado di sorreggere il proprio peso, collassa causando l'improvviso sprofondamento della superficie. il fenomeno avviene generalmente in tempi rapidi (talvolta nell'arco di pochi minuti o ore) e in occasione di eventi piovosi significativi e prolungati che inducono una variazione del contenuto in acqua, e quindi della plasticità, delle coltri di copertura. le doline di collasso risultano inoltre di gran lunga meno numerose rispetto a quelle di subsidenza, anche perché spesso tempestivamente riempite con materiali di riporto; a ciò si aggiunge l'effetto dei processi erosivi e di rimodellamento che possono in breve tempo mutare l'originario aspetto delle cavità di collasso in semplici depressioni chiuse. 462 g. fioraso et al. fig. 6 meccanismi genetici delle doline di subsidenza e di collasso (modificato da tihansky, 1999). 1: gesso; 2: coltri di copertura; 3: prodotti residuali della dissoluzione e riempimenti; 4: cavità carsiche. evolutionary model of cover-subsidence and cover-collapse sinkholes (from tihansky, 1999, modified). 1: gypsum; 2: sedimentary cover; 3: residual sediments and filling deposits; 4: karst cavities. fig. 7 dolina di collasso di circa 70 m di diametro impostata al contatto tra il membro siltosoargilloso delle argille azzurre e il ctv, fra gli abitati di cocconato e montiglio. alcuni sondaggi effettuati 200 m circa più a nord hanno intercettato, a profondità comprese tra gli 11 e i 16 m, numerose cavità carsiche prive di riempimenti e di dimensioni comprese tra 0,5 e 4 m. cover-collapse sinkhole, 70 m in diameter, located at the contact between ctv and argille azzurre silty-clayey member, between cocconato and montiglio villages. some drill-holes placed 200 m to the north intercepted many karst cavities at a depth of 11÷16 m. karst features have a diameter of 0,5÷4 m and are devoid of sediments. le doline osservabili nel monferrato mostrano spesso caratteri morfologici intermedi tra i fenomeni puri di subsidenza e di collasso (fig. 7): ciò è da mettere in relazione da un lato con le diverse possibili combinazioni dei meccanismi genetici descritti, dall'altro con la composizione granulometrica e lo spessore delle coltri di copertura coinvolte. le doline di subsidenza si concentrano infatti in aree nelle quali la matrice marnoso-argillosa del ctv è caratterizzata da spessori non superiori a qualche decina di metri: coltri più potenti, infatti, attenuano il risentimento superficiale del fenomeno di assestamento al punto da risultare morfologicamente impercettibile. le doline di collasso si verificano invece in aree nelle quali lo spessore delle coltri di copertura è relativamente modesto e indicativamente inferiore ai 10÷15 m: minore, infatti, è il volume dei sedimenti coinvolto, più immediate e appariscenti risulteranno le manifestazioni di sprofondamento. 5. riempimenti carsici la presenza di una coltre di copertura pressoché continua al di sopra dell'intervallo evaporitico ha consentito, parallelamente al procedere della dissoluzione, il trasferimento di ingenti quantità di sedimenti all’interno dei circuiti carsici (fig. 3). ciò ha causato il riempimento e l'occlusione di considerevoli tratti del reticolato ipogeo, interferendo sulle modalità di circolazione delle acque sotterranee e condizionando i processi dissolutivi in atto nelle zone attive e più profonde dei sistemi. l'eterogeneità delle successioni al tetto dei banchi di gesso, alquanto diversificate in termini di facies, spessore ed età, rende indubbiamente più intricata l'interpretazione dei meccanismi di piping. tuttavia, pur in assenza di chiari limiti spaziali tra lo sviluppo della morfogenesi carsica epigea e di quella ipogea, soprattutto in un ambiente con una spiccata dinamica evolutiva quale quello che caratterizza il carso gessoso, nelle cavità del monferrato e della collina di torino è stato possibile riconoscere almeno quattro distinte facies di riempimento: “brecce di collasso”; “argille e silt massivi o laminati”; “sabbie massive o stratificate”; “brecce di estrusione”. facies “a”: brecce di collasso rappresentano la facies di gran lunga più diffusa nell’ambito dell'epicarso: è costituita da sedimenti caotici di aspetto brecciato, con clasti poligenici angolosi di taglia compresa tra 0,2 e 2÷3 cm immersi in una scarsa matrice siltoso-argillosa o siltoso-sabbiosa (fig. 8). i clasti sono costituiti da frammenti di marne argillose e argille cui si aggiungono, in percentuali variabili, frammenti millimetrico-centimetrici di calcari concrezionali e vacuolari: in questi ultimi le microcavità, spesso di forma prismatica e di taglia millimetrica, sono vuote o riempite da calcite spatica e riproducono fedelmente la forma di originari cristalli di gesso cresciuti in una matrice siltoso-argillosa. all'interno delle brecce si rinvengono talvolta clasti di gesso di taglia compresa tra 1÷2 cm e 15÷20 cm (es. cava gessi di moncalvo). ai corpi brecciati sono talvolta associate tasche e lenti di spessore centimetrico-decimetrico di sabbie siltose a stratificazione piano-parallela orizzontale in posizione marginale e al contatto con le pareti delle cavità. le brecce derivano in gran parte dallo smantellamento delle coltri di copertura poste al tetto delle bancate gessose, costituite in primo luogo dai termini postevaporitici del ctv e dal membro siltoso-argilloso delle argille azzurre (cfr. fig. 2). un ulteriore apporto proviene dalla rielaborazione dei sedimenti “residuali” prodotti dalla concentrazione, all’interfaccia gesso-coperture, delle frazioni carbonatica, argillosa e quarzosa, insolubili o relativamente meno solubili, presenti all’interno del mosaico selenitico in percentuali comprese tra il 2 e il 5% (occella, 1958). le brecce possono essere interpretate come il prodotto del collasso gravitativo delle coltri di copertura all'interno delle cavità epicarsiche, con meccanismi che possono differire sensibilmente da luogo a luogo: in alcuni casi il riempimento si verifica a seguito del collasso della volta di vuoti epigei con conseguente rapida occlusione delle cavità (cfr. doline di collasso; fig. 6); in altri casi si tratta di un più graduale assestamento delle coltri di copertura, conseguente alla lenta dissoluzione epidermica del gesso e all’allargamento e all'approfondimento delle depressioni carsiche preesistenti (cfr. doline di subsidenza). lungo alcuni fronti di cava (es. moncalvo e bricco di murisengo) sono state individuate strutture da "iniezione" (sensu castellarin, 1982, e marabini & vai, 1989), localizzate all'interno di cavità cilindriche di grande diametro (3÷5 m) (fig. 3). si tratta di porzioni anche cospi463manifestazioni carsiche nelle evaporiti ... fig. 8 condotto epigeo a sviluppo verticale colmato da brecce di collasso (cava gessi di moncalvo). vertical epigean cavity filled with collapse breccia (gessi di moncalvo quarry). cue di marne e marne argillose biancastre compatte, iniettate (presumibilmente in condizioni di saturazione d'acqua ed elevata plasticità) all'interno delle cavità: il nucleo mostra una struttura caotica e disorganizzata, mentre i contatti con i sedimenti incassanti e con il gesso, sempre di natura discordante, sono netti e marcati da millimetriche fasce di frizione a struttura laminata (scaly fabric). gli episodi di riempimento delle cavità epicarsiche possono manifestarsi in un'unica soluzione oppure, in alternativa, come una successione di distinti eventi deposizionali. e' il caso di una cavità fusoidale messa in luce nella cava gessi di moncalvo, nella quale un nucleo di argillemarnose biancastre è avvolto da un rivestimento di 5÷20 cm di spessore costituito da silt sabbiosi porosi e privi di strutture (fig. 9); il contatto tra i due sedimenti è netto e non risulta dislocato dalle numerose superfici di scorrimento presenti invece all'interno del nucleo argilloso. in questo caso la polifasicità del riempimento è presumibilmente legata alla contrazione del nucleo argilloso per perdita del suo contenuto in acqua, che ha reso disponibile, all'interno della cavità, ulteriore spazio per lo sviluppo di un tardivo episodio di riempimento. facies “b”: argille e silt massivi o laminati costituiscono il riempimento di cavità ipogee a sviluppo orizzontale e, secondariamente, di alcuni tratti di camini e fusoidi (fig. 3). si tratta di sedimenti argillosi, siltoso-argillosi e siltosi di colore beige a laminazione piano-parallela orizzontale, con lamine di spessore millimetrico o decimillimetrico (fig. 10); con l'aumentare della frazione argillosa la laminazione svanisce lasciando il posto a una struttura massiva omogenea. la potenza di questi sedimenti è raramente superiore al metro, costituendo spesso intercalazioni irregolari e discontinue di modesto spessore (0,5÷10 cm) all'interno delle altre facies di riempimento. la presenza di argille massive o finemente laminate può essere ricondotta alla decantazione di sedimenti trasportati in sospensione dalle acque di percolazione all'interno di cavità periodicamente soggette a episodi di allagamento. le asperità create dalla deposizione di clasti di taglia centimetrico-millimetrica, provenienti dalle parti più elevate del circuito ipogeo, vengono regolarizzate da drappeggi di argille e silt legati a successivi episodi di decantazione. all'interno dei condotti carsici la laminazione è spesso disturbata dalla presenza di soft sediment deformations indotte da fenomeni di collasso gravitativo (fig. 11): esse si manifestano in primo luogo con blande ondulazioni a scala centimetrico-decimetrica e, meno frequentemente, con convoluzioni a stretto rag464 g. fioraso et al. fig. 9 nucleo di marna argillosa biancastra avvolto da un riempimento secondario di silt sabbiosi in una cavità messa in luce nella cava di gessi di moncalvo. karst cavity in gessi di moncalvo quarry with a core of clayey marl enveloped by secondary sandy silt coating. fig. 10 cavità a sviluppo orizzontale nella cava di montiglio. il riempimento, di circa 35 cm di spessore, è costituito da argille siltose laminate contenenti livelli sabbiosi di spessore centimetrico-millimetrico. horizontal cavity inside montiglio quarry. karst infill (35 cm in thick) is made-up of laminated clay and silty-clay with thin (centimetric to millimetric) sandy layers. gio di curvatura; queste strutture possono essere accompagnate da sgradinamenti dei livelli argillosi ad opera di gruppi di "faglie di gravità" dirette, ad alto angolo, con rigetti massimi di 2÷5 cm. le strutture descritte sono l'espressione di fenomeni di richiamo e insaccamento delle argille e dei silt saturi d'acqua verso le zone assiali delle cavità, per effetto del drenaggio e consolidamento dei sedimenti; in altri casi le deformazioni avvengono a causa della rimozione o del crollo del supporto basale del riempimento carsico, innescato dal trasferimento di una parte dei sedimenti nei settori più profondi e liberi del reticolo carsico. i riempimenti siltoso-argillosi sono spesso attraversati da filoncelli di esiguo spessore (al massimo 5÷6 mm) e sviluppo centimetrico-decimetrico, disposti ortogonalmente rispetto all'andamento della laminazione e contenenti sedimenti a granulometria più grossolana (sabbie e clasti argillosi millimetrici). anche queste strutture (mud cracks) sono causate dalla variazione del contenuto in acqua nelle argille e confermano la presenza di periodiche oscillazioni del livello della superficie freatica all'interno delle cavità, con episodi di disseccamento e contrazione dei sedimenti seguiti da nuove fasi di saturazione e riempimento. facies “c”: sabbie massive o stratificate ampiamente diffusa entro i condotti carsici ipogei a sviluppo verticale (fig. 3), questa facies è costituita da sabbie, sabbie siltose e sabbie ghiaiose a stratificazione piano-parallela e gradazione da normale a inversa. talvolta gli intervalli sabbiosi sono privi di strutture e si presentano con un aspetto massivo (fig. 12). la frazione ghiaioso-sabbiosa è rappresentata da clasti carbonatici di taglia millimetrica, arrotondati o subangolosi, e da granuli tondeggianti neri di ossidi di fe-mn di 0,5÷3 mm di diametro; in quantità subordinate si rinvengono frammenti di gusci di bivalvi e gasteropodi, macroforaminiferi bentonici e granuli di quarzo. il rapporto percentuale dei diversi componenti varia sensibilmente da un sistema carsico all'altro: in alcune cavità della cava di grana m.to, ad esempio, l'abbondanza di ossidi di fe-mn è tale da conferire alle sabbie una marcata colorazione bruna. tale circostanza è legata alla diversa composizione delle coltri di copertura situate nei punti di ingresso dei circuiti ipogei e ai diversi meccanismi di selezione, trasporto e concentrazione meccanica operanti nelle cavità di dissoluzione. le facies sabbiose costituiscono il prodotto dell'azione di fenomeni di piping e di correnti trattive in grado di veicolare sedimenti, talvolta anche grossolani, nel reticolato carsico ipogeo. 465manifestazioni carsiche nelle evaporiti ... fig. 11 alternanza di sedimenti siltoso-argillosi laminati (a) e sabbioso-siltosi (b), costituenti il riempimento di un condotto carsico di piccolo diametro (20÷22 cm) nella cava di grana m.to. i diversi livelli cromatici corrispondono a distinti episodi di riempimento della cavità. succession of laminated silty clay (a) and sandy silt (b) inside hypogean dissolution conduit 20÷22 cm in diameter (grana m.to quarry). every level correspond to a distinct episode in the infill sequence. all'interno dei riempimenti sabbiosi sono spesso presenti livelli e tasche di depositi siltoso-argillosi o, più frequentemente, clasti millimetrico-centimetrici argillosi di forma irregolare, provenienti dallo smantellamento dei tappi di sedimenti presenti nei tratti superiori dei condotti carsici. anche i sedimenti sabbiosi sono frequentemente destrutturati per la presenza di fenomeni di collasso simili a quelli descritti per le facies argillose (es. insaccamenti e dislocazioni di piccola entità): tuttavia, l'elevata permeabilità delle sabbie consente da un lato di escludere un legame delle deformazioni con la variazione del contenuto in acqua, dall'altro di ipotizzare fenomeni di assestamento dovuti al trasferimento dei sedimenti sottostanti nelle porzioni inferiori delle cavità. facies “d”: brecce di estrusione sono costituite da ammassi caotici di argille, siltargillosi e sabbie contenenti sporadici clasti carbonatici e talvolta piccoli frammenti di gesso (fig. 13). mostrano una struttura da brecciata a massiva con clasti e porzioni di sedimenti variamente deformati (ma al cui interno sono talvolta ancora preservate le originarie strutture sedimentarie) derivanti dalla rielaborazione delle facies descritte in precedenza. le brecce costituiscono il tipo di riempimento prevalente all'interno dei condotti carsici, rappresentando spesso l'unica facies presente (cfr. fig. 3). l'organizzazione interna delle brecce e i rapporti con le altre tipologie di riempimento, con le quali peraltro risultano spesso variamente associate, consentono di chiamare in causa per la genesi di questi sedimenti due distinti meccanismi: "autoclastismo", fenomeno guidato dalla gravità che comporta in un primo momento il graduale collasso e frammentazione delle originarie facies di riempimento (fig. 14), successivamente il trasferimento dei sedimenti nelle parti più profonde e libere dei condotti carsici sviluppatisi nel frattempo e la loro completa destrutturazione e caoticizzazione. il fenomeno si sviluppa a seguito dell'incremento del contenuto in acqua e del grado di plasticità dei materiali di riempimento. le diverse tappe e i diversi gradi evolutivi del fenomeno sono riconoscibili con buon dettaglio nelle cavità messe in luce nella cava di grana m.to, in cui risultano coinvolte alternanze di sabbie e silt argillosi laminati; "estrusione", fenomeno che si sviluppa quando all'interno dei condotti ipogei vengono a trovarsi tappi di sedimenti con un'elevata frazione siltoso-argillosa e quindi poco permeabili. anche in questo caso l'ingresso nel sistema carsico di consistenti volumi di acqua di percolazione porta in un primo momento all'imbibizione e alla saturazione dei sedimenti, successivamente a un incremento della loro plasticità: raggiunti valori critici di viscosità (di volta in volta controllati dalla composizione granulometrica del materiale di riempimento e dalla forma e dalle dimensioni della cavità), l'aumento di pressione legato al carico idraulico gravante sul tappo consente a quest'ultimo di essere gradualmente sospinto (ed "estruso" nei punti di maggiore restringimento dei condotti) e di fluire verso i tratti più profondi e liberi del circuito ipogeo. l'attrito esercitato dalla massa in movimento lungo le pareti della cavità comporta un grado di destrutturazione tale da fare assumere alla matrice siltoso-argillosa una struttura caotica, talvolta accompagnata da strutture di frizione al contatto con le pareti gessose. fenomeni di estrusione, del tutto simili a quelli segnalati in cavità carsiche nei gessi dell'appennino bolognese (trebbi, 1926), sono stati osservati nelle cave di montiglio e murisengo: alcune gallerie estrattive risultano infatti parzialmente o totalmente ostruite da imponenti colate di argille siltose estruse attraverso le numerose cavità carsiche, anche di piccolo diametro (25÷40 cm), intercettate dai fronti di coltivazione (fig. 15). 6. analisi biostratigrafica dei riempimenti carsici l'abbondanza delle microfaune riscontrate all'interno delle cavità carsiche ha fornito l'opportunità di individuare le aree sorgenti dei sedimenti in esse contenuti. a tale scopo è stata effettuata una serie di campionamenti in alcune cavità individuate nelle cave di grana m.to (cmp. grn-1), gessi di moncalvo (cmp. mnc-1, mnc-2 e mnc-3), montiglio (cmp. mnt-1 e mnt-2) e moncucco t. se (cmp. mc-12, mc-13 e mc23) (cfr. fig. 2). le analisi hanno consentito di caratterizzare, sulla base dell’associazione a foraminiferi 466 g. fioraso et al. fig. 12 sedimenti sabbiosi con clasti e intercalazioni siltosoargillose all'interno di un condotto carsico subverticale di circa 80 cm di diametro (cava di grana m.to). karst infill made-up of sands with silty-clayey lenses and chips inside subvertical dissolution conduit 80 cm in diameter (grana m.to quarry). planctonici, 6 dei 9 campioni esaminati (tab. 1), mentre l’analisi delle associazioni a foraminiferi bentonici ha fornito un quadro delle condizioni paleoambientali durante le quali i sedimenti andavano in origine a depositarsi (tab. 2). grana m.to: campione grn-1 il campione è stato prelevato in corrispondenza dell'unico livello di coltivazione presente nella dismessa cava in sotterraneo di grana m.to (fig. 2, sez. a-a'). si tratta di una complessa associazione di sedimenti sabbiosi e sabbioso-siltosi stratificati (facies "c") di colore variabile dal bruno al nocciola e variamente deformati, presenti all'interno di un articolato sistema di cavità che attraversano verticalmente il banco di gesso (cfr. fig. 12). l'analisi biostratigrafica ha 467manifestazioni carsiche nelle evaporiti ... fig. 13 melange di sedimenti siltoso-argillosi estrusi lungo un condotto carsico di circa 60 cm di diametro (cava di grana m.to). melange of silty-clayey sediments extruded along hypogean dissolution conduit 60 cm in diameter (grana m.to quarry). fig. 14 fenomeno di piping all'interno di un condotto carsico di piccole dimensioni (10÷15 cm di diametro) nella cava di grana m.to. piping phenomenon inside karst conduit 10÷15 cm in diameter (grana m.to quarry). fig. 15 solchi prodotti dall'estrusione di argille siltose attraverso una cavità carsica ubicata al tetto del terzo livello di coltivazione della cava di montiglio. furrows over a silty clay slub extruded from karst conduit at the roof of the workings in the third level of montiglio quarry. 468 g. fioraso et al. tab. 1 associazioni a foraminiferi planctonici riscontrate nei sedimenti di riempimento dei condotti carsici. assemblages of planktic foraminifers inside endokarst deposits. catapsydrax dissimilis x catapsydrax unicavus x dentoglobigerina altispira x globigerina apertura x globigerina bulloides x x globigerina decoraperta x globigerina falconensis x globigerina multiloba x globigerina nepenthes x globigerina praebulloides x x globigerina venezuelana x x globigerinita glutinata x globigerinoides bisphericus* x globigerinoides extremus x x globigerinoides obliquus x globigerinoides obliquus extremus x x globigerinoides quadrilobatus x globigerinoides sacculifer x x g r n -1 m n t -1 m n t -2 m c -1 2 m c -1 3 m c -2 3 globigerinoides sp. x globigerinoides subquadratus x globigerinoides trilobus x x globoquadrina baroemoenensis* x globoquadrina dehischens x x globoquadrina praedehischens* x globorotalia margaritae (rara) x x globorotalia menardii x globorotalia puncticulata x x globorotalia scitula x x globorotalia sp. x hastigerina siphonifera x neogloboquadrina acostaensis x neogloboquadrina dutertrei x orbulina bilobata x orbulina universa x x orbulina suturalis x x paragloborotalia mayeri x turborotalita quinqueloba x x x g r n -1 m n t -1 m n t -2 m c -1 2 m c -1 3 m c -2 3 ammonia beccarii x anomalinoides granosus x anomalinoides helicinus x anomalinoides ornatus x bolivina miocenica x brizalina arta x brizalina sp. x bulimina aculeata x bulimina echinata* x bulimina minima x cancris auriculus x cassidulina carinata x cibicides sp. x cibicidoides kullenbergi x cibicidoides pachydermus x cibicidoides pseudoungerianus x x cibicidoides robertsonianus x elphidium crispum x globobulimina affinis x globocassidulina subglobosa x gyroidinoides neosoldanii x gyroidinoides sp. x heterolepa bellincionii x heterolepa dertonensis x lenticulina calcar x lenticulina cultrata x lenticulina curvisepta x lenticulina inornata x lenticulina orbicularis x lenticulina rotulata x g r n -1 m n t -1 m n t -2 m c -1 2 m c -1 3 m c -2 3 lenticulina spinulosa x marginulina costata x marginulina crebricosta x martinottiella communis x x melonis barleanum x melonis pompilioides x melonis soldanii x neoeponides schreibersi x nodosaria raphanistrum x nodosaria raphanus x oridorsalis umbonatus x orthomorphina sp. x planulina ariminensis x x pullenia bulloides x pullenia salisbury x rectouvigerina siphogenerinoides x x saracenaria italica x sigmoilinita tenuis x siphonina reticulata x x sphaeroidina bulloides x spiroplectinella wrighty x stilostomella sp. x x textularia agglutinans x textularia soldanii x uvigerina auberiana x uvigerina pygmaea x uvigerina rutila x uvigerina striatissima x vaginulinopsis striatissima x vulvulina pennatula x g r n -1 m n t -1 m n t -2 m c -1 2 m c -1 3 m c -2 3 tab. 2 associazioni a foraminiferi bentonici riscontrate nei sedimenti di riempimento dei condotti carsici. assemblages of benthonic foraminifers inside endokarst deposits. messo in luce un'abbondante associazione a prevalenti foraminiferi bentonici e foraminiferi planctonici, cui si associano ostracodi, frammenti di echinidi e rari ittioliti. gli esemplari sono generalmente ben conservati e spesso di grandi dimensioni. sono stati rinvenuti in percentuali significative anche frammenti di gusci di bivalvi e di gasteropodi. nella frazione inorganica sono diffusamente presenti aggregati e concrezioni carbonatiche, cui si aggiungono, in percentuali minori, granuli millimetrici di ossidi di fe-mn, pirite e glauconite, queste ultime anche come modelli interni di foraminiferi. la presenza di globorotalia margaritae e di globorotalia puncticulata (tab. 2) consente di attribuire al pliocene inferiore (zancleano, zona mpl3; cita, 1975; rio et al., 1994) l’età delle associazioni. tra i taxa bentonici altre forme coeve, o con diffusione a tutto il pliocene inferiore, sono rappresentate da anomalinoides granosus, anomalinoides helicinus, anomalinoides ornatus, heterolepa bellincionii, heterolepa dertonensis, lenticulina spinulosa, uvigerina rutila e vaginulinopsis striatissima. l’associazione sembra indicativa della zona epibatiale superiore (scarpata continentale, prossima al margine della piattaforma), mentre la frequenza di esemplari di grandi dimensioni (in particolare di lenticulina spp. e di nodosaria spp.) sembra suggerire condizioni ambientali ottimali per i taxa. i risultati delle analisi consentono di interpretare i riempimenti delle cavità di grana m.to come il prodotto dell'infiltrazione e della rielaborazione di originari sedimenti riferibili al membro siltoso-argilloso delle argille azzurre (faa/9 in fig. 2). questa unità affiora estesamente lungo la sommità della dorsale collinare entro cui è impostato il giacimento di gesso, ed è separata dai sottostanti sedimenti del ctv da una discontinuità stratigrafica a valenza regionale (dela pierre et al., 2003a). gessi di moncalvo: campioni mnc-1, mnc-2 e mnc-3 i campioni sono stati prelevati lungo i fronti di coltivazione, attualmente dismessi, della cava a cielo aperto ubicata in località gessi di moncalvo: mnc-1 costituisce il riempimento siltoso e siltoso-sabbioso stratificato (facies "b" e "c") di una cavità a sviluppo orizzontale localizzata all'interno del terzo banco gessoso; mnc-2 è costituito da marne argillose biancastre provenienti dal nucleo di una cavità intercettata dagli scavi lungo il terzo banco (cfr. fig. 9); le argille massive del campione mnc-3 sono state infine prelevate all'interno di un piccolo fusoide localizzato entro il ciclo evaporitico inferiore (fig. 2, sez. b-b'). tutti i campioni sono risultati sterili dal punto di vista faunistico. solo in mnc-1 è stato rilevato un melange di resti di organismi marini, fra i quali rarissimi radioli di echinodermi e otoliti di pesci, e di organismi terrestri, fra i quali un molare di micromammifero non determinabile. pertanto, è probabile che in questo settore l'infiltrazione di sedimenti nelle cavità carsiche sia avvenuto a spese di originarie marne siltose biancastre, localmente costituenti la matrice del ctv, che risultano sterili o caratterizzate da associazioni a foraminiferi poco significative (dela pierre et al., 2003a). montiglio: campioni mnt-1 e mnt-2 i campioni provengono rispettivamente dal primo e dal terzo livello di coltivazione della dismessa cava in sotterraneo di montiglio (fig. 2, sez. c-c'), il cui imbocco è posto poche decine di metri a sud dall'alveo del t. versa. per mnt-1 si tratta di sedimenti sabbiosi e argillosi grigi stratificati (facies "b" e "c"), contenenti locali concentrazioni di molluschi dulcicoli (planorbis sp.), ospitati in un ampio e irregolare condotto subverticale parzialmente percorribile; mnt-2 è invece costituito da argille massive e silt argillosi laminati beige (facies "b") ospitati in una cavità a sviluppo orizzontale (cfr. fig. 10). la frazione inorganica è formata da sabbie carbonatiche, noduli millimetrici di ossidi di fe-mn e granuli di pietre verdi, quarzo e muscovite. in entrambi i campioni le associazioni a foraminiferi risultano piuttosto ricche. in particolare, in mnt-1 è stata riscontrata una fauna ottimamente conservata di età pliocenica inferiore (zancleano, zona mpl4a), caratterizzata dalla presenza di globorotalia puncticulata. in associazione sono state rinvenute specie fortemente ricristallizzate, e talora deformate, attribuibili al messiniano, al burdigaliano superiore e al burdigaliano inferiore (evidenziate con * in tab. 2), indicative di un importante melange faunistico. l’associazione a foraminiferi bentonici risulta piuttosto varia ed è caratterizzata da specie infaunali ed epifaunali ialine tipiche della zona epibatiale inferiore mesobatiale (scarpata continentale). per quanto concerne invece il campione mnt-2, l’associazione a foraminiferi è molto più scarsa. la presenza di catapsydrax dissimilis , c. unicavus e globoquadrina dehischens consente tuttavia di attribuire come età limite superiore dei sedimenti il miocene inferiore (burdigaliano, zona n5/6; novaretti et al., 1995). dal punto di vista paleoambientale l’associazione sembrerebbe invece indicativa della zona epibatiale superiore. il mixing faunistico che caratterizza i campioni mnt-1 e mnt-2 trova riscontro nelle particolari associazioni a foraminiferi (riferibili all'intervallo compreso tra l'eocene e il messiniano inferiore) riconosciute da dela pierre et al. (2002) nelle mud breccias del complesso caotico di parona, affioranti nell'area circostante le cave di montiglio, sul versante sinistro della valle versa: secondo questi autori la presenza di simili miscelazioni sarebbe da ricondurre a meccanismi di gravity sliding e di diapirismo, attivi nel messiniano superiore, che avrebbero smembrato l'intervallo evaporitico già deposto e coinvolto localmente anche i termini della successione pre-messiniana. la presenza di associazioni a microfossili di età pliocenica inferiore (zona mpl4a) deriverebbe invece dall'infiltrazione nel sistema carsico di sedimenti riferibili al membro silsoso-argilloso delle argille azzurre, affiorante 300 m a se dell'imbocco della cava. moncucco t.se: campioni mc-12, mc-13 e mc-23 i campioni mc-12 e mc-13 sono costituiti da argille massive di colore beige (facies "b") e provengono da due cavità messe in luce lungo il primo livello di coltivazione della cava di moncucco t.se (fig. 2, sez. d-d'). il campione mc-23, costituito da argille marnose verdi (facies "b"), proviene invece da una cavità ubicata in corrispondenza del quarto livello di coltivazione (fig. 2, sez. d-d’). i campioni mc-12 e mc-13 mostrano caratteri similari e sono caratterizzati da una microfauna piuttosto scarsa e di dimensioni estremamente ridotte (cfr. 469manifestazioni carsiche nelle evaporiti ... tabb. 2 e 3). in mc-12 la presenza di globigerina multiloba è indicativa di un’età miocenica superiore (messiniano, subzona a globigerina multiloba, d’onofrio et al., 1975), mentre in mc-13 la presenza di globigerina quinqueloba permette di attribuire un’etàlimite inferiore delle microfaune al miocene superiore (tortoniano, zona n17). i rarissimi foraminiferi bentonici rinvenuti appartengono a specie infaunali ialine tipiche di fondali fangosi e talora disossici: in questo caso la scarsità di ossigenazione giustificherebbe le ridotte dimensioni degli organismi rinvenuti. mc-23 si discosta notevolmente dai precedenti campioni in quanto costituito da una microfauna ricca, diversificata e ben conservata. globorotalia margaritae è indicativa di un’età pliocenica inferiore (zancleano, zona mpl2). la microfauna bentonica, caratterizzata da forme infaunali ialine e agglutinanti, sembra indicativa della zona epibatiale (scarpata continentale). i risultati delle analisi riflettono la particolarità dell'assetto stratigrafico e strutturale recentemente riconosciuto nella zona di moncucco t.se (polino, 2002; irace et al., 2002): la presenza in mc-12 di globigerina multiloba deriverebbe dal trasferimento, all'interno del sistema carsico, di sedimenti appartenenti ai termini messiniani delle marne di s. agata fossili, che nell'area di cava risultano direttamente giustapposte all'intervallo evaporitico tramite un duplice sistema di faglie transpressive a direzione n170÷180° (festa et al., 2002); le associazioni fossilifere di età pliocenica inferiore presenti nel campione mc-23 proverrebbero invece dalla rielaborazione di sedimenti riferibili al membro siltosoargilloso delle argille azzurre che sigillano, con una superficie di discontinuità, la sottostante successione miocenica. 7. distribuzione dei sistemi carsici la localizzazione e la tipologia delle manifestazioni carsiche riscontrate nel monferrato e nella collina di torino appaiono strettamente dipendenti da un lato dall'assetto stratigrafico e strutturale localmente assunto dal ctv, dall'altro dall'entità dell'esumazione dei rilievi collinari intercorsa nell'intervallo pliocenico-quaternario. a partire dalla direttrice chieri altavilla m.to, lungo la quale affiora in modo pressoché ininterrotto, il ctv immerge mediamente di 2÷5° verso le aree depocentrali di alessandria (a est) e di carmagnola villanova d'asti (a ovest). in questa fascia il ctv risulta inoltre confinato al di sotto di una potente coltre di copertura pliocenico-quaternaria costituita dalle argille azzurre, dalle sabbie di asti e dal complesso "villafranchiano" auct., rappresentato dalle sabbie di ferrere, dai silt di s. martino e dal sintema di morialdo (carraro, 1996; boano & forno, 1999; dela pierre et al., 2003a). nel dettaglio, tuttavia, l'orientazione delle bancate gessose risulta in molti punti molto meno regolare e soprattutto appare svincolata rispetto all'andamento regionale del ctv. quest'ultimo è stato inoltre esposto a un tasso di esumazione progressivamente maggiore procedendo da sud verso nord, in accordo con il carattere differenziale delle deformazioni tettoniche che hanno accompagnato la strutturazione del thrust frontale padano (pieri & groppi, 1981; costa, 2003). al contempo si è verificata la graduale dissezione del nascente rilievo collinare (e conseguentemente del ctv) da parte del reticolato idrografico locale, le cui tracce, in forma di superfici terrazzate e di lembi di depositi, sono diffusamente conservati sul versante sud della dorsale collina di torino monferrato (polino, 2002; dela pierre et al., 2003a). questa evoluzione ha imposto, nel tempo, chiari vincoli fisici all'impostazione e allo sviluppo dei fenomeni dissolutivi, che risultano inevitabilmente condizionati dal contesto morfologico superficiale: l'emersione del rilievo collinare ha infatti consentito l'instaurazione del gradiente idrodinamico necessario alle acque di percolazione per defluire dai settori di alimentazione alle aree in cui le stesse, una volta permeati gli ammassi gessosi, vengono restituite al reticolato idrografico di superficie, che di norma avviene in corrispondenza del punto di raccordo tra il livello di base carsico e gli attuali fondovalle alluvionali. alla luce dei dati fin qui esposti, i fenomeni di dissoluzione descritti possono essere inquadrabili in un carso di "interstrato" (intrastratal karst; palmer & palmer, 1989; klimchouk, 1996a), nel quale la solubilizzazione del gesso avviene al di sotto di un'originaria coltre di copertura impermeabile. l'assetto geometrico del ctv e i rapporti con le limitrofe unità affioranti nel monferrato hanno permesso di individuare tre tipologie carsiche (fig. 16), distinte essenzialmente in base al grado di dissezione ed esposizione subaerea dell'intervallo gessoso e alla distribuzione tridimensionale e alla morfologia delle cavità di dissoluzione: 1) "carso inciso" (entrenched karst; klimchouk, 1996a), nel quale i blocchi selenitici del ctv sono profondamente dissecati e drenati dal reticolato idrografico. il gradiente idraulico che guida la circolazione delle acque sotterranee è più elevato rispetto agli adiacenti settori del sistema carsico. il reticolo di cavità ipogee si estende all'interno delle bancate gessose coinvolgendone l'intera potenza carsificabile (50÷60 m), ma con un'intensità dei fenomeni dissolutivi (in termini di sezione, profondità, frequenza e interconnessione dei condotti) decrescente verso il basso. lo spessore delle coltri di copertura, solitamente rappresentate dalla matrice del ctv e secondariamente da sedimenti pliocenici riferibili alle argille azzurre, è relativamente scarso (< 10 m) e tale da ricalcare l'andamento della morfologia epigea. nel carso inciso gli effetti del risentimento superficiale dei fenomeni di dissoluzione raggiungono la loro massima intensità, confermati dall'elevata frequenza delle doline di subsidenza e di collasso (fioraso & boano, 2002). questa tipologia carsica si manifesta prevalentemente nella fascia di distribuzione del ctv al contatto con i termini più vecchi della successione terziaria (es. marne di mincengo e di s. agata fossili) e in prossimità del settore assiale della dorsale collina di torino monferrato: esempi di carso inciso sono visibili in corrispondenza delle cave di murisengo, della pirenta (fig. 2, sez. c-c') e di moncucco t.se (fig. 2, sez. d-d'). 2) "carso subgiacente" (subjacent karst; klimchouk, 1996a), nel quale i termini evaporitici sono solo parzialmente dissecati dall'idrografia di superficie. i sistemi carsici appaiono ben sviluppati unicamente al di sopra del livello di base locale, sebbene la dissoluzione possa intaccare, in qualche caso, anche i 470 g. fioraso et al. volumi gessosi a maggiore profondità. gli effetti della morfogenesi carsica raramente si trasmettono fino alla superficie, poiché attenuati dallo spessore delle coltri di copertura che può raggiungere valori di 20÷50 m. queste ultime sono costituite dalla matrice del ctv e dalle propaggini settentrionali della successione pliocenica rappresentata dalle argille azzurre e dalle sabbie di asti. questa tipologia carsica coinvolge buona parte della successione messiniana affiorante nel monferrato settentrionale: i settori nei quali meglio si esprimono le caratteristiche del carso subgiacente sono quelli di grana m.to (fig. 2, sez. a-a'), gessi di moncalvo (fig. 2, sez. b-b') e montiglio. 3) "carso profondo" (deep-seated karst; klimchouk, 1996a), ospitato nelle porzioni meno esumate del ctv e che pertanto risultano sigillate al di sotto della successione pliocenica monferrina. il carsismo in questo caso è privo di una qualsivoglia espressione morfologica, essendo confinato al di sotto di una potente coltre di copertura il cui spessore è il più delle volte superiore ai 40÷50 m. la presenza di fenomeni di dissoluzione profondi è rilevabile unicamente da elementi di tipo "indiretto". in occasione della realizzazione di un pozzo per acqua nei pressi di chieri (lungo il margine meridionale della collina di torino) è stata intercettata all'interno dell'intervallo gessoso una cavità a 80 m dal piano campagna, contenente acque fortemente arricchite in ioni solfato (sacco, 1925). analoga situazione è stata riscontrata nella porzione più meridionale della cava in sotterraneo di gessi di moncalvo, nella quale un sondaggio esplorativo, spinto alcune decine di metri al di sotto dell'attuale livello di coltivazione, ha intercettato abbondanti venute di acque fredde in pressione (~ 3 bar) fortemente arricchite in solfati: diversamente da tutte le manifestazioni carsiche fin qui analizzate, per le quali si è verificata una dissoluzione per descensum dei fluidi, nel secondo caso la mineralizzazione delle acque può essere attribuita all'effetto dissolutivo causato dalla risalita di fluidi profondi (dissoluzione per ascensum) in corrispondenza del prolungamento verso se delle strutture a carattere transpressivo che delimitano l'unità tettonica di ponzano-villadeati (dela pierre et al., 2003a). la presenza di circuiti idrogeologici relativamente complessi e profondi era già stata peraltro ipotizzata da bortolami et al. (2003) per spiegare la presenza, nel monferrato settentrionale, di alcune sorgenti fredde a chimismo solfato-calcico (es. pirenta di murisengo e fontana di calliano; fig. 1b): secondo questi autori, l'arricchimento in ioni solfato con valori prossimi al punto di saturazione sarebbe da ricercare nella risalita di acque lungo zone o superfici di faglia poste in prossimità o all'interno dei banchi gessosi messiniani. 8. meccanismi genetici ed evolutivi dei fenomeni carsici la diffusione delle cavità carsiche nei gessi del monferrato e della collina di torino può essere in primo luogo ricondotta all'elevata solubilità di queste rocce, che in acqua pura possono raggiungere concentrazioni piuttosto elevate e comprese tra 2,22 e 2,67 g l-1 in funzione della temperatura (jakucs, 1977). una conferma della rapidità evolutiva del carso gessoso nel btp è fornita da una serie di misurazioni effettuate da cucchi et al. (1998) per stimare la velocità della dissoluzione sviluppata sulla superficie di alcuni affioramenti selenitici nell'astigiano: i risultati dell'indagine, ottenuti con l'ausilio della metodologia mem (micro-erosion-meter method), hanno consentito di determinare un tasso di dissoluzione pari a 0,93 mm ogni 1000 mm di pioggia, a fronte di un valore medio riscontrato nei gessi messiniani italiani di 0,85 mm ogni 1000 mm di pioggia. significativo per apprezzare la velocità del fenomeno, 471manifestazioni carsiche nelle evaporiti ... fig. 16 schema di distribuzione dei fenomeni carsici nei livelli gessosi del complesso caotico di valle versa a sud della dorsale collina di torino monferrato (non in scala). la sezione corrisponde a un transetto idealmente orientato in direzione nord-sud. idealized cross-section (not in scale) traced along n-s transect with distribution of karst phenomena in the gypsum blocks of the valle versa chaotic complex, southern side of the collina di torino monferrato ridge. questo dato fa tuttavia riferimento a un carso esposto alla dissoluzione subaerea e consente unicamente di valutare l'ordine di grandezza della morfogenesi carsica: esso, infatti, è di difficile estrapolazione all'intero contesto messiniano del btp, caratterizzato quasi ovunque (ad eccezione dei pochi affioramenti subaerei prossimi alle aree di cava) da un carso coperto, nel quale il deflusso delle acque di infiltrazione è drasticamente ostacolato dalle coltri argillose. queste rallentano sensibilmente i fenomeni dissolutivi all'interfaccia gesso-coperture (macaluso et al., 2001), svolgendo un'azione protettiva nei confronti del gesso. infatti, grazie alla diminuzione della velocità di deflusso (funzione della granulometria, della composizione mineralogica e dello spessore delle coperture), le acque a contatto con i gessi raggiungono molto rapidamente la soglia di saturazione: in assenza di un rapido ricambio idrologico viene così a generarsi una sottile frangia ad elevata salinità che inibisce, o quanto meno rallenta, la dissoluzione. i bassi coefficienti di permeabilità che contraddistinguono l'intervallo messiniano (bortolami et al., 1989) sono tali da condizionare anche le modalità di assorbimento, da parte dei sistemi carsici, delle acque di precipitazione. le aree di affioramento del ctv e delle argille azzurre sono infatti prive di un reticolato idrografico ben definito, cui si accompagna l'assenza di inghiottitoi e punti di assorbimento: l'infiltrazione avviene pertanto in modo diffuso, con acque in grado di permeare solo gradualmente le coltri di copertura. queste ultime svolgono in tal senso la funzione di "filtro", rallentando la velocità di ingresso delle acque nel reticolato ipogeo: nelle cavità minerarie, infatti, si rileva uno sfasamento temporale dei picchi di acque edotte rispetto ai periodi di precipitazione, di entità variabile (al massimo qualche giorno), in funzione dello spessore e della natura dei terreni attraversati. solo una volta raggiunta l'interfaccia con il gesso, avvallamenti e depressioni epicarsiche possono costituire un richiamo per le acque di percolazione (con locali effetti di concentrazione e amplificazione della cinetica dissolutiva), che in tal modo hanno facile gioco nell'insinuarsi entro la rete di discontinuità, in primo luogo fratture e faglie, ben riconoscibili all'interno delle bancate evaporitiche. infatti, se i valori di permeabilità primaria dei gessi risultano in prima approssimazione trascurabili (le percentuali dei vuoti sono comprese tra il 4 e l'8% del volume gessoso, con punte massime del 15%; occella, 1958), ben diverso, e sicuramente predominante, è il ruolo svolto dalla fessurazione, grazie alla maglia di sistemi di fratture di estensione metricodecimetrica e di faglie di lunghezza da ettometrica a chilometrica (morelli, 2000; morelli et al., 2001). nel btp il gesso assume quindi le caratteristiche di un acquifero eterogeneo, anisotropo e discontinuo, nel quale le discontinuità costituiscono l'elemento primario nella veicolazione dell'acqua e conseguentemente nel controllo dei processi di dissoluzione (fig. 3). si citano ad esempio le cave di moncucco t.se e di grana m.to, nelle quali alcune cavità carsiche risultano impostate lungo faglie subverticali con direzione rispettivamente n100° e n150°. l'influenza delle strutture fragili risulta ancor più accentuato in presenza di fasce cataclastiche di spessore variabile da pochi millimetri a qualche metro, nelle quali il gesso si presenta minutamente brecciato. la diminuzione della taglia dei cristalli comporta una maggiore superficie specifica intergranulare esposta al contatto con l'acqua e un'accentuazione dei processi di solubilizzazione (cucchi et al., 1998; macaluso et al., 2001): secondo sonnenfeld (1984) la solubilità del gesso raggiunge i massimi valori per cristalli di taglia compresa tra 0,2 e 0,5 µm. ciò favorisce lo sviluppo di fenomeni di dissoluzione differenziali e l'impostazione di vie preferenziali per la veicolazione dei fluidi lungo i piani di faglia anziché all'interno delle bancate selenitiche. il procedere della speleogenesi determina quindi l'ampliamento delle discontinuità e il passaggio da originarie condizioni di flusso laminare lento a flussi turbolenti rapidi. si osserva infine un'accelerazione dei meccanismi dissolutivi in relazione ai minori tempi di contatto acqua-roccia e ai maggiori volumi di acqua sottosatura in transito nei condotti di neoformazione (james & lupton, 1978). questi ultimi divengono in tal modo gli elementi dominanti nella circolazione sotterranea, con rapido sviluppo di fenomeni di cattura delle acque a spese delle fratture e dei condotti idrologicamente meno efficienti (veni, 1987). la dissoluzione esercita nel tempo un controllo non solo sullo sviluppo e sulla configurazione del reticolato carsico (e in ultima analisi sulla macro-permeabilità dell'ammasso roccioso), ma anche sul chimismo e sul potenziale dissolutivo delle acque di percolazione. nell'epicarso la solubilizzazione dei cristalli selenitici risulta infatti molto intensa poiché svolta da fluidi meteorici ampiamente sottosaturi in solfati. l'aggressività dell'acqua diminuisce tuttavia in breve tempo e a breve distanza dal punto di ingresso nel sistema carsico, con conseguente arresto della dissoluzione una volta raggiunte concentrazioni in ioni so4 2prossime al punto di saturazione. nel monferrato questa ipotesi è confermata dalla diminuzione verso il basso del numero di pozzi e gallerie e del loro grado di interconnessione idraulica: all'elevato numero di forme di dissoluzione riscontrate nei primi 15÷20 m delle bancate di gesso si contrappone il ridotto numero di cavità intercettate nei livelli di coltivazione più profondi. anche gli interstrati marnoso-argillosi, generalmente di esigua potenza (20÷150 cm in media) ma caratterizzati da bassi valori di permeabilità, possono condizionare la circolazione delle acque, determinando la "compartimentazione" delle singole bancate evaporitiche: si tratta tuttavia di un controllo a valenza locale, in quanto i sistemi di faglie e-w, ne-sw e n-s che dislocano i blocchi gessosi garantiscono la presenza di soluzioni di continuità nell'ambito dei livelli euxinici. in sintesi l'efficienza dei meccanismi di dissoluzione risulta essere mediata: 1) dalle caratteristiche lito-strutturali della roccia (tessitura; composizione e purezza del gesso, che nel monferrato si aggira sul 95÷98%; presenza di interstrati argillosi, faglie, fratture e microfratture); 2) dalle caratteristiche idrauliche dei circuiti ipogei (sezione, numero e grado di gerarchizzazione e di interconnessione laterale dei condotti); 3) dalle condizioni di sottosaturazione in solfato di calcio dei fluidi. un fattore aggiuntivo che controlla i precedenti e che interviene sulle modalità di sviluppo del carso gessoso, è rappresentato dalla periodicità con cui opera la dissoluzione in relazione alla distribuzione temporale degli eventi piovosi: i volumi di acqua edotti dalle cave 472 g. fioraso et al. in sotterraneo di gessi di moncalvo e di murisengo, mediamente compresi tra i 3 e i 6 l/s, ricalcano l'andamento e l'entità delle precipitazioni. ciò da un lato conferma il carattere epidermico del fenomeno carsico nel btp, dall'altro evidenzia come la dissoluzione avvenga ad opera di acque di percolazione in ambienti ipogei sostanzialmente insaturi, che solo in occasione di prolungati eventi piovosi possono risultare temporaneamente saturi a seguito dell'innalzamento del livello di falda. tale ipotesi è supportata dalla presenza, all'interno di molte cavità, di abbondanti quantitativi di sedimenti argilloso-siltosi decantati e di strutture da disseccamento compatibili con rapide oscillazioni del livello piezometrico (cfr. § 5). inoltre, l'assenza di condotti carsici al di sotto degli attuali fondovalle (es. cave di gessi di moncalvo, murisengo e montiglio; fig. 2), indicherebbe un netto rallentamento della dissoluzione in prossimità della superficie della falda freatica, a sua volta in raccordo con il livello di base locale. infatti, sebbene le acque possano esercitare nella zona satura un attacco chimico sostanzialmente uniforme lungo tutte le discontinuità, le basse velocità di deflusso che contraddistinguono la zona satura rispetto a quella areata non consentono un rapido ricambio delle acque, inibendo l'azione dissolutiva che in tal modo non può svilupparsi nella sua completezza. 9. il fenomeno carsico nel quadro dell'evoluzione pliocenico-quaternaria del monferrato e della collina di torino la dissoluzione carsica può manifestarsi in due distinti momenti della storia evolutiva di una successione evaporitica: nel corso della precipitazione della successione ("carsismo singenetico"), per effetto di variazioni indotte nel contesto deposizionale da oscillazioni eustatiche del livello marino o da variazioni chimico-fisiche (es. diluizione) delle acque di precipitazione (warren, 1999); successivamente alla definitiva chiusura del ciclo evaporitico. nel secondo caso l'età, le modalità di sviluppo e le caratteristiche del carsismo differiscono in funzione del diverso contesto geodinamico e climatico nel quale la successione evaporitica viene di volta in volta a inserirsi nell'arco della propria evoluzione: variazioni nell'assetto stratigrafico, tettonico e morfologico possono infatti compromettere la funzionalità idrogeologica dei sistemi carsici già da tempo impostati, dando luogo a fenomeni di “fossilizzazione” dei circuiti ipogei (paleokarst; bosak et al., 1989), oppure consentire la ripresa di fenomeni dissolutivi da lungo tempo inattivi (exhumed karst; bosak et al., 1989). alla luce dei dati fin qui esposti, le manifestazioni carsiche individuate nella fascia del btp compresa tra il f. po (a nord) e il f. tanaro (a sud) mostrano di essersi sviluppate, sia pure con gradienti sensibilmente diversi, per effetto di una graduale esumazione della successione messiniana. pur in assenza di precisi elementi cronologici di riferimento, numerosi sono gli elementi di carattere stratigrafico, strutturale e morfologico che consentono di inquadrare temporalmente la formazione delle cavità e dei riempimenti, nonché di ricostruire l’evoluzione del complesso carsico del monferrato e della collina di torino. l'analisi, in termini puramente geometrici, dei rapporti intercorrenti fra l'orientazione delle bancate gessose e la vergenza delle forme dissolutive (condotti a sviluppo verticale e soprattutto cavità a "soffitto piatto", che possono in tal senso essere utilizzati come marker della deformazione) evidenzia un chiaro rapporto di sequenzialità del fenomeno carsico rispetto all'assetto stratigrafico locale del ctv. il divario appare meno marcato nei settori in cui minore è l'entità dell'esumazione del btp conseguente all'attivazione del thrust padano (es. grana m.to e molcalvo); risulta invece sensibilmente maggiore nei settori (es. montiglio e moncucco t.se) in cui la componente tettonica pliocenico-quaternaria si è sovrapposta ai fenomeni di collasso gravitativo e di caoticizzazione intra-messiniani che hanno coinvolto buona parte dell’intervallo evaporitico (dela pierre et al., 2002; 2003a) (fig. 16). lo smembramento di quest’ultimo ha inoltre comportato la frammentazione del complesso carsico monferrino in un mosaico di subsistemi, ciascuno dei quali confinato all'interno dei singoli blocchi gessosi (sia pure con estensione talvolta superiore al km2), che risultano idrogeologicamente sigillati dalla matrice argillosa del ctv. l’assenza di interconnessioni dirette tra i vari subsistemi rende i fenomeni dissolutivi all'interno di questi ultimi sostanzialmente indipendenti, pur in un comune e più ampio quadro evolutivo esteso a scala regionale. in questo contesto stratigrafico, l'assetto strutturale rilevabile all'interno delle bancate gessose ha svolto un condizionamento locale e sostanzialmente passivo nella veicolazione in profondità delle acque di dissoluzione (maggior permeabilità delle zone di faglia), nella localizzazione dei fenomeni dissolutivi (maggior solubilità del gesso nelle zone fratturate) e quindi nella circolazione idro-carsica. non sono invece emersi episodi di interferenza sin-morfogenetica tra le strutture tettoniche rilevate all’interno delle bancate gessose e i sistemi carsici, che in più punti vengono in diverso modo a intersecarsi. l’analisi della distribuzione tridimensionale dei fenomeni dissolutivi evidenzia un forte parallelismo tra l'evoluzione morfotettonica quaternaria del rilievo collinare monferrino e lo sviluppo del carsismo: salvo alcune eccezioni, legate alla locale presenza di circuiti profondi con risalita di acque lungo sistemi di faglia (cfr. murisengo e gessi di moncalvo), la dissoluzione è confinata al di sopra del livello di base locale, che costituisce l'elemento di raccordo di tutti i principali fondovalle alluvionali (fig. 16). il livello di base attuale e precedente assume quindi il ruolo di marker morfostratigrafico, che si esprime all’interno dei sistemi carsici con la presenza dei "soffitti di dissoluzione". il locale buon grado di correlazione altimetrica che queste forme mostrano talvolta con le superfici terrazzate distribuite a varie quote lungo le dorsali collinari del monferrato, avvalora l'ipotesi secondo cui tali cavità materializzerebbero delle paleo-superfici freatiche originariamente in raccordo con antichi livelli di base. i depositi fluviali conservati sulle superfici terrazzate più elevate mostrano complessivamente un discreto grado di evoluzione pedogenetica cui corrisponde un indice di colore pari a 5÷7,5 yr (alessio et al., 1982; carraro & valpreda, 1991; dela pierre et al., 2003a): ciò consente di stimare, quanto 473manifestazioni carsiche nelle evaporiti ... meno nei settori di maggior maturità dei sistemi carsici (entrenched karst) come quelli osservati a sud di murisengo e di moncucco t.se (cfr. fig. 2), un’età delle forme di dissoluzione sopravvissute al rimodellamento compresa tra la parte superiore del pleistocene medio e l’attuale. i sistemi idro-carsici del monferrato si sviluppano ed evolvono quindi in continua risposta alle variazioni indotte sull'assetto morfologico locale: all'esumazione del ctv si contrappone la migrazione relativa del fronte di dissoluzione, che viene in tal modo a collocarsi in posizione via via più prossima alla base dell'intervallo gessoso, meccanismo chiaramente rilevabile nei settori che ospitano esempi di subjacent karst (klimchouk, 1996a) (fig. 2, sez. a-a'; fig. 16). il rapporto di interrelazione dinamica tra esumazione tettonica e sviluppo del processo carsico è inoltre in accordo con le informazioni ricavate dall'analisi dei sedimenti di riempimento. due sono gli elementi che in tal senso confermano e affinano il quadro evolutivo proposto: a) le associazioni a microforaminiferi riscontrate nei riempimenti carsici campionati appaiono diversificate in funzione del diverso contesto stratigrafico locale e coprono un’intervallo temporale compreso tra il burdigaliano inferiore e il pliocene inferiore. appare quindi evidente come l’introduzione dei sedimenti nei circuiti ipogei sia iniziata a partire da un contesto tettono-stratigrafico sostanzialmente simile a quello attualmente osservabile e quindi successivo al picco deformativo che ha interessato la fascia settentrionale del btp. quest'ultimo coincide, a scala regionale, alla tettonica che ha determinato da un lato il sovrascorrimento della successione cenozoica del btp sull'avanfossa padana in relazione alla propagazione nord-vergente del thrust padano (pieri & groppi, 1981), dall'altro la risedimentazione gravitativa del ctv (dela pierre et al., 2003a). gli effetti della deformazione risultano particolarmente evidenti nell’area circostante la cava di moncucco t.se, nella quale le marne di s. agata fossili sono sovrapposte sui sedimenti del ctv (festa et al., 2002); b) le complesse alternanze di riempimenti carsici testimoniano il succedersi di episodi erosivo-deposizionali a carattere "ciclico": a momenti di totale occlusione dei condotti (accompagnati dalla formazione di sedimenti massivi o laminati legati a decantazione in acqua) si sono alternate improvvise disostruzioni delle cavità con smantellamento dei riempimenti sovrastanti e trasferimento degli stessi (cfr. “brecce di estrusione”) nelle parti più profonde dei sistemi carsici. questo meccanismo evolutivo ha imposto da un lato una periodica rielaborazione dei sedimenti di riempimento già presenti nei condotti ipogei, dall’altro il continuo apporto di nuovi sedimenti nelle parti più superficiali del sistema. le cavità carsiche del btp e i sedimenti in esse ospitati rappresentano in sintesi il prodotto di fenomeni di dissoluzione e sedimentazione polifasici e policronologici tuttora in evoluzione. nelle masse gessose del ctv sono registrati alcuni degli episodi carsogenetici che di volta in volta vi si sono impressi per effetto del graduale sollevamento ed esumazione dell’intervallo messiniano: quest'ultimo ha in tal modo acquisito un crescente grado di incarsimento in relazione all'approfondimento relativo del fronte di dissoluzione. la presenza di un reticolato ipogeo a prevalente sviluppo verticale è inoltre la conferma di una significativa mobilità verticale del rilievo ospitante il complesso carsico messiniano (nicod, 2002) e di una dissoluzione che ha operato in ambienti ipogei sostanzialmente insaturi (klimchouk, 1996b). nonostante ciò la presenza di livelli di base fossili (materializzati dalla combinazione di cavità a "soffitto piatto" e di lembi di depositi fluviali terrazzati) suggerisce che al graduale processo di esumazione si siano intervallate brevi fasi di relativa stabilità tettonica. simultaneamente, il rimodellamento del rilievo e la componente epigea della dissoluzione hanno comportato un sostanziale “ritocco” dell'originaria configurazione della superficie sommitale dei blocchi evaporitici (variabile in funzione del grado di esposizione subaerea del gesso) e la cancellazione delle tracce di fasi di dissoluzione pregresse. ringraziamenti gli autori desiderano ringraziare il dott. a. festa per aver messo a disposizione la sezione geologica della cava di moncucco t.se e la prof.sa d. violanti per aver effettuato l’esame del campione grn-1. si ringrazia inoltre il prof. f. carraro per la revisione critica del manoscritto e per i preziosi suggerimenti forniti. lavoro effettuato con fondi cnr – istituto di geoscienze e georisorse, sezione di torino. bibliografia alessio m., allegri l., ambrosetti p., bartolomei g., bella f., belluomini g., calderoni g., carraro f., charrier g., cortesi c., esu d., forno m.g., improta s., manfra l. & petrone v. 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(it isnn 03943356, 2004). la presente nota breve ha lo scopo di presentare e descrivere i tratti salienti di una sezione geologica bidimensionale ricostruita nella pianura lodigiana, tra melegnano ed il fiume po, per una lunghezza di oltre 45 km. l’occasione per questo lavoro è stata fornita dalla perforazione di un transetto continuo di sondaggi, pali di fondazione, pozzi ed altre opere di scavo, eseguito per la realizzazione della linea ferroviaria ad alta velocità milano – bologna. scopo del lavoro è principalmente la presentazione di una nuova ed inedita base di dati litologici e geocronometrici, interpretati in via preliminare dal punto di vista stratigrafico. la sezione ricostruita illustra la diversa organizzazione stratigrafica di tre settori. il settore della pianura lodigiana, settentrionale, è caratterizzato dalla presenza di sei unità stratigrafiche di origine fluvioglaciale e fluviale di provenienza sudalpina, di età compresa tra il pleistocene medio (?) e l’olocene; queste si appoggiano lateralmente verso sud sui sedimenti fini di ambiente marino e transizionale della formazione di san colombano (pliocene p.p. – pleistocene inferiore); quest’ultima è coinvolta nel sollevamento tettonico dell’omonima anticlinale di rampa appenninica. il settore del colle di san colombano, immediatamente a sud del precedente, è caratterizzato dalla risalita fino alle vicinanze del piano campagna della formazione già citata, che risulta troncata a tetto da profonde incisioni vallive e ricoperta dalle unità fluvioglaciali e fluviali del pleistocene medio/superiore – olocene, tanto verso nord quanto verso sud. nel settore del po, meridionale, i corpi fluviali olocenici (fino a storici) del po, ricoprono due unità fluvioglaciali e fluviali, di età compresa tra il pleistocene medio (?) ed il pleistocene superiore, alimentate verosimilmente in buona parte dal lato appenninico. l’inferiore di questi corpi ricopre i sedimenti marini del colle di san colombano, riempiendo profonde incisioni vallive sepolte. abstract: baio m. et al., geology of the quaternary succession in the subsurface between melegnano and piacenza. (it isnn 0394-3356, 2004). the current work illustrates a stratigraphic cross-section which crosses the southern plain of lodi, as far south as the po river, 45 km long. the work aims to present the newly available database consisting of the stratigraphic and petrographic data obtained by several tens of boreholes, foundation piles and wells that were drilled for building the high speed railway milano – bologna; these data are complemented by some new geochronometrical 14c ages obtained on samples of organic matter and wood fragments. a preliminary 2d stratigraphic interpretation of this database is provided, in the form of a working hypothesis. the geological cross-section illustrates subsurface stratigraphy, down to a maximum depth of 100 m below sea level. three sectors have been separated on the basis of the geometrical and stratigraphic features, from north to south. in the lodi plain sector (north) six stratigraphic units have been introduced, spanning the middle pleistocene (?) to holocene. the post glacial fluviatile unit, confined within the lambro valley, is entrenched into the glaciofluvial sediments which presumably correlate with the lgm alloformations of the alpine area. these latter unconformably overlay two glacio-fluvial units which have been correlated with different alloformations of the besnate allogroup (late – middle pleistocene), based on 14c age determinations, facies and gravel petrography. the lowermost two units are interpreted as fluviatile and glaciofluvial deposits which might be related to glaciations predating the age of the besnate allogroup. the glaciofluvial units terminate southwards, in the central san colombano hill sector, onto the lowermost stratigraphic unit, whose marine and transitional depositional environments suggest a correlation with the outcropping san colombano fm. (pliocene p.p. – early pleistocene). in the subsurface of this sector, the unit reaches shallow depths (20 m below topography) due to tectonic uplift of the san colombano apenninic ramp anticline. in this same sector it is deeply dissected by an erosion surface which mimics the shape of entrenched valleys. it is covered by the uppermost pleistocene sediments which correlate with the most recent alloformations of the besnate allogroup and with the lgm sediments. in the southern po sector, the holocene po alluvial deposits are cut into glaciofluvial gravel and sands of late pleistocene age, whose petrography suggests a mixing of dominant apenninic gravel with subordinate alpine-derived clasts. the middle – upper pleistocene sediments of the po sector, progressively cover northwards the ancient marine and transitional fine-grained sediments of the san colombano hill sector, which are progressively lowered southwards to depths higher than 100 m below sea level and are no longer reached by boreholes and wells. parole chiave: geologia di sottosuolo, pianura padana, quaternario. keywords: po plain, quaternary, subsurface geology. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 355-359 introduzione i numerosissimi sondaggi geognostici a carotaggio continuo eseguiti lungo il tratto lombardo del tracciato ferroviario alta velocità, spinti nel sottosuolo fino alla profondità media di 40÷50 m e tra i 60 e i 120 m nella zona del po, hanno permesso l'elaborazione di una sezione geologica ininterrotta da melegnano a piacenza (fig. 1). la base dei dati è costituita da nuovi rilievi geologici, in larga parte ancora in corso, dalle stratigrafie sopraccitate alle quali vanno aggiunte le numerosissime stratigrafie ottenute durante l’esecuzione dei pali di fondazione, integrate da numerose altre provenienti da varie banche dati, da campioni di carotaggi solo in parte studiati, da nuove datazioni col metodo del 14c e da recentissime informazioni di tipo archeologico. questa breve nota ha lo scopo di presentare una 356 m. baio, r. bersezio & a. bini versione preliminare della sezione geologica citata, relativa alla fascia dei primi 100÷150 m di sottosuolo. la stessa, lunga circa 45 km, continua poi, attraversando trasversalmente la pianura padana, in un’altra sezione geologica (valloni, baio, bedulli 2003) fino quasi a bologna, per una lunghezza complessiva di entrambe le sezioni di circa 185 km. il lavoro è basato sulla correlazione stratigrafica, eseguita lungo un transetto bidimensionale, delle principali superfici di discontinuità che separano unità stratigrafiche individuate anche sulla base dei caratteri tessiturali e composizionali; queste sono frequentemente caratterizzate dallo sviluppo di sequenze cicliche, spesso di tipo fining upward. sono state riconosciute nove unità informali che rappresentano un primo approccio per gli studi tridimensionali della pianura attualmente in corso. inquadramento geologico la zona di pianura attraversata dalla sezione è localizzata a sud dell'anfiteatro morenico del lario. i sedimenti pleistocenici interessati da questo studio si sviluppano a tetto della successione marina del pliocene pleistocene pro parte e rappresentano i depositi fluvioglaciali e fluviali distali rispetto alle unità glaciali riconosciute a nord (bini, 1997a; b; strini, 2001). questo settore di pianura presenta un’ampia superficie con pendenza quasi uniforme verso se, con gradienti inferiori all'1,5 ‰; in questa superficie sono incisi gli alvei dei fiumi principali, approfonditi entro scarpate di terrazzo decametriche. la stessa superficie è percorsa da paleoalvei con tracce meandriformi delimitati da scarpate metriche e talora occupati da corsi d'acqua sottodimensionati (castiglioni & pellegrini, 2001). poco a nord del po la superficie è interrotta dal rilievo del colle di san colombano (fig. 1) derivante dal sollevamento tettonico pleistocenico di un'anticlinale di rampa connessa con i fronti dei sovrascorrimenti appenninici settentrionali (fantoni et al, 2001; 2003). in affioramento sul colle sono presenti sedimenti marini del pleistocene inferiore (desio, 1952; formazione di san colombano, anfossi et al, 1967). la superficie sommitale della pianura non si raccorda con il livello di base del po essendo troncata dalla scarpata decametrica del terrazzo di somaglia (fig. 2), il quale presenta in questo settore il suo massimo dislivello. l'altezza della scarpata decresce sia verso est sia verso ovest sino ad annullarsi, suggerendo una relazione con il sollevamento dei rilievi appenninici esterni. la sezione melegnano piacenza nella sezione sono riconoscibili tre settori, differenziati su basi stratigrafiche: settore della pianura lodigiana, a nord, settore del colle di san colombano (area di pianura a est del rilievo stesso) e settore del po, a valle della scarpata di somaglia (fig. 2). nel seguito la stratigrafia del sottosuolo relativa a questi settori viene descritta a partire da sud (settore del po) e dall'alto stratigrafico verso il basso. unità a: sabbiosa ghiaiosa limosa. essa affiora nel settore del po e nell'alveo del lambro (settore della pianura lodigiana) (fig. 2). nel settore del po, a valle della scarpata di somaglia, essa comprende i sedimenti deposti dal fiume po in alvei incassati, colmati da tappi di sedimenti fini in seguito all’abbandono dei meandri. a questi si associano sedimenti prevalentemente sabbiosi deposti da corsi d’acqua minori (brembiolino, guardalobbia, mortizza) che incidono o tagliano i meandri fossili del po o vi si sovrappongono. l'età olocenica è testimoniata dalla posizione geometrica e stratigrafica, da una data 14c (2.052 ÷ 2.080, 2.134 ÷ 2.296 cal bc; stuiver e reimer, 1993) eseguita su legni presenti a –12,5 m dal p.c. e dal rinvenimento a -5/-7 m dal p.c. di frammenti fluitati di laterizi di età romana associati a sedimenti grossolani. nella valle del lambro l'unità a è organizzata in tre ordini di terrazzi formati da sedimenti sabbioso ghiaiosi, organizzati in barre di meandro e riempimenti di canali di rotta; a questi si associano sedimenti limoso argillosi di tracimazione. l'età storica dei depositi costituenti il terrazzo intermedio è documentata dai laterizi embricati nelle forme di fondo ghiaiose. unità b: sabbiosa limosa. essa costituisce l'unità superficiale nel settore della pianura lodigiana e nel settore del colle di san colombano sino alla scarpata di somaglia che la interrompe. si tratta di depositi prevalentemente sabbiosi, di colore da bruno a giallo oliva, organizzati in sequenze metriche localmente coronate da facies fini limose argillose talora ricche in materia organica. in questa unità sono inclusi anche i corpi lenticolari sabbiosi ghiaiosi corrispondenti al riempimento della paleovalle del sillaro (fig. 2). lo spessore massimo è dell'ordine dei dieci metri. la composizione petrografica delle ghiaie è caratterizzata dalla prevalenza dei litici sedimentari sui litici magmatici e metamorfici di fig. 1 ubicazione della sezione presentata in fig. 2. index map and location of the geological cross-section of fig. 2. 357assetto geologico della successione ... f ig . 2 – s e zi o n e g e o lo g ic a i n te rp re ta ti va n e lla b a ss a p ia n u ra l o d ig ia n a t ra m e le g n a n o e p ia c e n z a . i s o n d a g g i u ti liz za ti s o n o i n d ic a ti c o n l in e e n e re v e rt ic a li. i p a ll in i n e ri i n d ic a n o l’ u b ic a zi o n e d e i c a m p io n i p e r d a ta zi o n i 1 4 c , i tr ia n g o li n e ri i n d ic a n o i liv e lli r ic c h i d i m a te ri a o rg a n ic a e fr u s to li ve g e ta li, i q u a d ra ti n e ri in d ic a n o i r it ro va m e n ti d i m a c ro fo ss ili . l e e tà ra d io m e tr ic h e n o n c a lib ra te s o n o r ip o rt a te fu o ri s e z io n e ( s i c o n fr o n ti n o n e l te s to c o n a lc u n i v a lo ri c a lib ra ti ). l ’e sa g e ra zi o n e v e rt ic a le è c ir c a 5 0 :1 . in te rp re ta ti ve g e o lo g ic a l c ro s s -s e c ti o n th ro u g h t h e s o u th e rn l o d i p la in ( m e le g an an o – p ia c e n za ). b o ro h o le s a re l o c a te d b y ve rt ic a l lin e s; b la c k d o ts in d ic ate l o c a ti o n o f 1 4 c a g e d e te rm in a ti o n s ; th e b la c k tr ia n g le s in d ic a te s o rg an ic m at te r an d w o o d y fr a g m e n ts ; b la c k sq u ar e s in d ic at e s fi n d in g s o f m a c ro fo ss il s . n o n c a li b ra te d ra d io m e tr ic a g e s a re re p o rt e d a b o v e th e to p o g ra p h y (c o m p a re w it h t e xt f o r so m e c al ib ra te d v al u e s) . v e rt ic al e xa g g e ra ti o n i s a b o u t 5 0 :1 . 358 provenienza alpina. alla base dell'unità un campione di frustoli vegetali ha fornito un'età 14c di 19.909 ÷ 20.785 cal bc (fig.2). unità c: ghiaiosa. essa è presente unicamente nel settore del po, delimitata a tetto e a letto da superfici erosionali talora profondamente incise. essa è costituita da grossi e potenti corpi sedimentari deposti dal po. osservazioni preliminari sulla composizione petrografica delle ghiaie indicano una netta prevalenza di clasti di provenienza appenninica (valle trebbia?) con una modesta presenza di piccoli clasti di provenienza alpina (porfidi, ortogneiss, rocce metamorfiche). alla base dell’unità c è stata ottenuta un'età 14c di 24.833 ± 200 a bp (fig.2). unità d: sabbiosa ghiaiosa. essa è presente nel settore della pianura lodigiana e nel settore del colle di san colombano sino alla scarpata di somaglia che la interrompe (fig. 2). si tratta di sequenze cicliche positive di ghiaie passanti a sabbie di colore grigio, coronate da sedimenti limoso argillosi. questi caratteri sono definiti principalmente nel settore della pianura lodigiana anche in base ad alcune osservazioni effettuate in scavi eseguiti lateralmente rispetto alla traccia della sezione. la continuità verso se di questa unità è attualmente ipotizzata sulla base dei caratteri tessiturali di questo pacco di sedimenti che risulta inquadrato stratigraficamente tra le sabbie brune dell'unità b (a tetto) e le ghiaie prevalenti dell'unità f (a letto). la composizione petrografica delle ghiaie mostra inoltre una marcata differenza rispetto alle ghiaie dell'unità b in quanto è caratterizzata dalla prevalenza dei litici magmatici e metamorfici su quelli sedimentari. due date 14c ottenute da campioni raccolti a tetto e a letto dell'unità nei pressi del fiume lambro (fig. 2) hanno fornito età di 22.035 ± 300 a bp e 23.145 ± 340 a bp. unità e: limosa argillosa e ghiaiosa sabbiosa. essa è presente unicamente a partire dal settore del colle di san colombano. nel settore del po l'unità e comprende una successione prevalentemente limosa argillosa che ricopre potenti corpi sabbiosi ghiaiosi. la successione fine superiore è costituita da un orizzonte esteso trasversalmente alla valle del po per circa 8 9 km, avente spessore variabile da 3 m a 10 m. le litologie prevalenti sono limi, limi sabbiosi e argille localmente ricche di sostanza organica, frustoli vegetali e legni. seguono verso il basso alternanze sottilmente stratificate di limi sabbiosi e sabbie fini. i corpi grossolani sottostanti presentano spessori maggiori di ottanta metri e risultano costituiti da sedimenti sabbiosi ghiaiosi deposti da un paleo po. la composizione petrografica delle ghiaie suggerisce la prevalente provenienza dei clasti dai rilievi appenninici (val trebbia?) con una modesta presenza di piccoli clasti di provenienza alpina (ortogneiss, porfidi e rocce metamorfiche). l'unità termina in corrispondenza del settore del colle di san colombano in appoggio su una superficie erosionale incisa nei sedimenti fini della sottostante unità l. queste geometrie vengono evidenziate da una ricostruzione bidimensionale rispetto alla quale si possono avere variazioni laterali molto significative; per esempio l'emersione del colle di san colombano pochi chilometri a ovest della sezione implica geometrie sostanzialmente diverse. datazioni 14c su legni hanno fornito età maggiori di 42.590 a bp a circa 20 m dal p.c.(fig.2). frequentemente si passa verso il basso in modo graduale a sabbie medio – fini e sabbie grossolane debolmente ghiaiose; localmente si ha un passaggio brusco a ghiaie grossolane con ciottoli e sabbia; non di rado tale passaggio è evidenziato dalla presenza di legni anche di grosse dimensioni (un frammento di legno ha fornito un’età 14c maggiore di 43.580 a bp). unità f: ghiaiosa sabbiosa. nella sezione l’unità f è stata definita a nord del settore del colle di san colombano; le sue relazioni con l’unità e si realizzano lateralmente allo stesso, fuori dalla traccia della sezione. si tratta di due successioni ghiaiose sabbiose sovrapposte, potenti complessivamente fino a 40 m. l’inferiore costituisce una sequenza positiva, con passaggio da corpi ghiaiosi ad unità sabbiose fino a pochi e sottili livelli limosi raramente ricchi in materia organica. la superiore è costituita da un potente pacco di ghiaie, da medie a grossolane, che si sfrangia verso sud in un gruppo di sequenze minori, ghiaiose sabbiose, con livelli limosi argillosi sottili e poco frequenti. la composizione petrografia delle ghiaie è caratterizzata dalla prevalenza dei litici metamorfici e magmatici sui litici sedimentari, di provenienza sudalpina. la terminazione dell’unità f, in appoggio sui sedimenti fini dell’unità l è interpretata in corrispondenza del settore del colle di san colombano. unità g e unità h: sabbiose limose argillose. queste due unità rappresentano i sedimenti più profondi raggiunti dalla sezione di fig.2. come l’unità f, esse sono state riconosciute a nord del settore del colle di san colombano, ove viene interpretato il loro appoggio verticale e laterale sui sedimenti fini dell’unità l. anche in questo caso le relazioni stratigrafiche e geometriche con la parte inferiore dell’unità e non sono interpretabili attraverso questo transetto, realizzandosi lateralmente rispetto alla struttura del colle di san colombano. l’unità g è costituita da sequenze cicliche positive, sabbiose limose argillose, localmente coronate a tetto da un livello limoso argilloso metrico, la cui continuità laterale è interrotta dalla superficie di erosione a letto dell’unità f. anche l’unità h comprende sequenze sabbiose limose argillose, positive, che si caratterizzano per la continuità laterale e lo spessore sempre almeno metrico degli intervalli fini, talora ricchi di materia organica. essa è separata dalla soprastante unità g per mezzo di un livello sommitale limoso argilloso di spessore plurimetrico, continuo pressoché lungo tutta la sezione di fig. 2. l’assenza di ghiaie medie impedisce di confrontare la composizione petrografica di questi sedimenti con quella delle unità soprastanti. la base dell’unità h non è raggiunta lungo il transetto analizzato, se non in corrispondenza della risalita dei sedimenti fini che costituiscono l’unità l, ove viene interpretato l’appoggio su una superficie erosionale molto marcata ed irregolare (fig. 2). unità l: argillosa limosa. essa è stata individuata nel settore del po a profondità superiori a 80 m dal p.c.(fig. 2, roggia brembiolina), mentre a sud di somaglia, in un sondaggio agip, è presente fra –120 m e – 160m circa dal p.c.. nel settore della pianura lodigiana l’unità l non è attraversata dai sondaggi alle profondità massime raggiunte di 150 m sotto il piano m. baio, r. bersezio & a. bini 359 campagna. l'unità è costituita da alternanze sottilmente stratificate di limi, sabbie fini limose e limi argillosi associati a limi sabbiosi, sabbie e sabbie fini limose, ad argille di colore nero ricche di sostanza organica, a limi argillosi con tasche di macrofossili ed a livelli di torba. i fossili si rinvengono nella zona di cascina mandella a una profondità di circa -28 m dal p.c. e a sud di somaglia in un sondaggio agip a partire da -120 m circa dal p.c.. i caratteri di questi sedimenti sono del tutto confrontabili con quelli delle litologie tipiche della formazione di san colombano (pleistocene inf. – pliocene?; anfossi et al, 1967). la forte risalita di quota osservata nel settore del colle di san colombano e la geometria profondamente incisa della superficie di erosione al tetto dell’unità l confermano il suo coinvolgimento nella struttura tettonica positiva di san colombano (desio, 1952). discussione sulla base dei dati stratigrafici disponibili nella sezione bidimensionale presentata è possibile unicamente proporre ipotesi relative all'attribuzione stratigrafica delle unità informali individuate. di conseguenza quanto viene suggerito nel seguito costituisce un'ipotesi di lavoro per gli studi in corso attualmente sull'intera pianura lodigiana. l'unità a, contenuta nei terrazzi inferiori del po e del lambro è correlabile con l'unità postglaciale descritta più a nord (bini, 1997) ed è perciò attribuibile al pleistocene superiore olocene. l'unità b è di più difficile attribuzione presentando, alla base, età radiometriche compatibili con l'intervallo di tempo relativo allo lgm alpino (bini, 1997). d'altra parte i sedimenti sommitali appartenenti a questa unità sono tuttora non datati e sulla base delle caratteristiche tessiturali male si prestano ad essere interpretati come sedimenti fluvioglaciali distali. per questo motivo non si esclude che la parte superiore dell'unità b possa essere attribuita alle fasi di ritiro del ghiacciaio relativo allo lgm o addirittura all'unità postglaciale. l'unità c è presente unicamente nel settore del po e presenta alla base età compatibili con il pleistocene superiore prelgm. il carattere grossolano dei sedimenti di questa unità induce ad interpretarla come costituita da depositi fluvioglaciali attribuibili quindi all'intervallo temporale occupato dai fluvioglaciali più recenti appartenenti all'allogruppo di besnate. in assenza di datazioni non si può escludere che la porzione sommitale di questa unità possa essere correlata con fasi glaciali più recenti (lgm) (valloni, baio, bedulli 2003). analogamente l'unità d, presente prevalentemente nella pianura lodigiana, risulta attribuibile per età e facies ad un fluvioglaciale correlabile con l’allogruppo di besnate. l'unità e, presente nel settore del po e del colle di san colombano, ha età superiori al limite del metodo 14c. essa è difficilmente suddivisibile al suo interno. considerata la sua estensione stratigrafica, fino all'appoggio sull'unità l, ed i suoi caratteri litologici, non si può suggerire altro se non il fatto che essa comprenda i fluvioglaciali e i fluviali pleistocenici precedenti l’allogruppo di besnate. in posizione geometrica equivalente all'unità e, a nord del settore del colle di san colombano, sono presenti le unità f, g e h. non si posseggono date geocronometriche per queste unità. sulla base dei caratteri tessiturali e litologici esse possono venire interpretate come successioni fluvioglaciali. tra queste la f presenta i depositi più prossimali ed è plausibilmente correlabile con i fluvioglaciali antichi dell'allogruppo di besnate. alla base dell'intera successione fluviale e fluvioglaciale è presente l'unità l, con caratteri attribuibili ad ambienti transizionali e marini. essa è sollevata in corrispondenza del settore del colle di san colombano e profondamente erosa a tetto. di conseguenza essa risulta probabilmente correlabile con la formazione di san colombano affiorante sul rilievo omonimo ed attribuita al pliocene superiore ? pleistocene inferiore. bibliografia anfossi g., boni a., comizzoli g., desio a., gelati r., laureri s., passeri l., petrucci f. e venzo s. (1967) carta geologica d'italia alla scala 1:100.000, foglio 60 piacenza (seconda edizione) servizio geologico d'italia, roma bini a. (1997a) problems and methodologies in the study of the quaternary deposits of the southern side of the alps geol. ins., 2/2, 11 – 20, lugano. bini a. (1997b) stratigraphy, chronology and palaeogeography of quaternary deposits of the area between the ticino and olona rivers (italy switzerland) geol. ins., 2/2, 21-46. castiglioni g.b. & g.b. pellegrini (2001) note illustrative della carta geomorfologica della pianura padana suppl. geogr. fis. dinam. quat., iv, 207 pp. desio a. (1952) movimenti orogenici quaternari nella pianura padana rend. acc. naz. lincei fantoni r., massari f., minervini m., rogledi s. & rossi m. (2001) il messiniano del margine sudalpino lombardo: relazioni tra contesto strutturale e stratigrafico deposizionale geol. ins., 6/1, 95-108. lugano. fantoni r., bersezio r. &. forcella f. (2003) alpine structure and deformation chronology at the southern alps po plain border in lombardy boll soc. geol. it., in press. strini a. (2001) gli occhi pollini della brianza orientale: genesi ed evoluzione del fenomeno nel quadro geologico regionale. tesi di dottorato inedita, xiii ciclo, università di milano, 550 pp. s t u i v e r m. & r e i m e r p.j. (1993) radiocarbon calibration program calib rev4 4.2 radiocarbon, 35, 215 230. valloni r., baio m. & bedulli f. (2003) architettura deposizionale del pleistocene superiore nel sottosuolo della media pianura emiliana. geoitalia, 4° forum fist, riassunti, 125 – 127. ms. ricevuto l’11 maggio 2004 testo definitivo ricevuto il 2 novembre 2004 ms. received: may 11, 2004 final text received: november 2, 2004. assetto geologico della successione ... imp.capezzuoli& i “travertini” in italia: proposta di una nuova nomenclatura basata sui caratteri genetici. enrico capezzuoli & anna gandin dipartimento di scienze della terra, via laterina 8, 53100 siena. e.mail: capezzuoli@unisi.it; gandin@unisi.it riassunto: capezzuoli e. & gandin a., i “travertini” in italia: proposta di una nuova nomenclatura basata sui caratteri genetici. (it issn 0394-3356, 2004). il termine “travertino” viene generalmente usato in italiano per indicare indistintamente un’ampia varietà di carbonati continentali deposti da acque lacustri, palustri o fluviali, oppure da sorgenti calde o fredde, formatisi cioè in condizioni chimico-fisiche, biologiche e climatiche anche molto differenti. i risultati delle ricerche più recenti indicano che queste differenze si riflettono sia sui caratteri geochimici sia sui caratteri litologici di questi depositi che sono tuttora in formazione e di cui si ritrovano abbondanti tracce nel recente passato. i caratteri distintivi dei vari tipi di carbonati sono tutt’ora argomento di discussione ma è opinione di molti autori che sulla base dei caratteri petrologici affiancati anche da quelli geochimici, sia possibile effettuare una classificazione genetica affidabile. in conseguenza sarebbe logico che solamente i depositi concrezionari collegati alle sorgenti idrotermali vengano denominati travertino che è un termine nato per i depositi formatisi intorno alle sorgenti calde di tivoli. i travertini di norma sono relativamente poco influenzati dai fattori climatici, sono caratterizzati da facies prevalentemente cristalline disposte secondo una regolare laminazione, mostrano alti tassi di accrescimento, scarso contenuto organico e un arricchimento in c13, carbonio inorganico disciolto totale, magnesio, stronzio e zolfo. d’altra parte, per i carbonati continentali non termali, derivati cioè da acque fredde di origine sia fluvio-palustre sia di sorgente, è stato coniato nella letteratura anglosassone più recente il nome di calcareous tufa. essi si formano come incrostazioni carbonatiche su supporti formati prevalentemente da organismi vegetali superiori (briofite, giunchi, ecc.) con tassi di deposizione di norma bassi, sono influenzati dalle condizioni climatiche, e contengono basse concentrazioni di tdic, di stronzio e di magnesio con accentuato impoverimento in c13. per rendere più facili le correlazioni e la comprensione nella comunità scientifica, si ritiene necessario normalizzare anche in italiano la terminologia dei carbonati continentali. a tale scopo si propone di riservare il termine travertino solo ai carbonati continentali deposti in corrispondenza di un sistema di sorgente termale, e di utilizzare il termine calcareous tufa per i carbonati precipitati da acque a temperatura ambiente in sistemi fluvio-palustri. abstract: capezzuoli e. & gandin a., the “travertine” in italy: proposal of a new nomenclature based on the genetics characters. (it issn 0394-3356, 2004). the word “travertine” in the common italian language, is generally used for a variety of continental carbonates deposited by hotor cold-waters, in the surroundings of spring vents, or in fluvial, palustrine or lacustrine systems. the geochemical signature as well as the lithological and petrographic features of these limestones, appear to be controlled by the physiochemical conditions of the spring waters and/or the depositional environment and climate. the results of recent research indicates that the petrologic features can be used for a genetic classification. the term travertine, which for a long time has been used to designate the ornamental/building stone quarried in the thermal deposits of tivoli, should be reserved to calcium carbonate deposits associated to hydrothermal spring systems. this lithology which is slightly enriched in 13c, tdic, strontium and sulphur, appears to be hardly dependent upon climate. it is characterized by a primary, low-porosity crystalline fabric, fine daily laminae, and by bacteria and cyanophytes as the dominant organic components. on the other hand, the term calcareous tufa, coined in the british literature, refers to calcium carbonate deposits formed under a cool water regime, around karst spring complexes and/or in a fluvio-palustrine environment. this lithology which is depleted in 13c and shows tdic concentrations more or less in equilibrium with the soil atmosphere, appears to be highly dependent upon climatic factors. it is characterized by normally low depositional rates, poor bedding, commonly lenticular, highly porous bodies and abundant remains of microand macrophytes, bacteria and invertebrates. the distinction between these two groups of lithotypes is not univocal since the cool water calcareous tufa deposits are often found as the natural lateral prosecution of travertines far from the thermal-spring complex. however preliminary, compared analyses of travertine and calcareous tufa fabrics show the possibility of using petrographic criteria for their distinction. the discrimination of the two types of deposits appear to be essential in the interpretation of the tectonic, climatic and anthropologic meaning of the fossil continental carbonates. for this reason, it is important that the scientific community working on continental carbonates adopt even in italy a suitable terminology reserving the term travertine for the deposits deriving from hot-spring complexes, and calcareous tufa for the sediments deposited near cold water springs and in fluvialpalustrine systems. parole chiave: calcareous tufa; calcari continentali; nomenclatura. keywords: travertine, calcareous tufa, continental carbonates, classification. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 273-284 1. introduzione i depositi carbonatici continentali rappresentano una particolare categoria di sedimenti che negli ultimi anni hanno attirato l’interesse dei ricercatori per le informazioni che possono fornire. la loro distribuzione a livello planetario è strettamente legata alla presenza di corpi rocciosi carbonatici che rendono possibile l’arricchimento in calcio delle acque meteoriche circolanti. non esiste una classificazione univoca di questi depositi, ma è comunque possibile individuare i principali litotipi sulla base dei processi genetici e degli ambienti deposizionali. vengono infatti, differenziati: gli speleotemi (sedimenti formatisi in grotte carsiche), le calcrete 274 e. capezzuoli & a. gandin (collegati a processi pedogenetici), e con il generico termine “travertino” i calcari concrezionari originariamente depositati come fanghi in ambiente lacustre, quelli precipitati da acque carbonatate calde in corrispondenza di sorgenti termali, o da acque carbonatate a temperatura ambiente in corrispondenza di sorgenti carsiche e/o di sistemi fluvio-palustri (cipriani et al., 1972, 1977; ferreri, 1985; foucault & raoult, 1986). tuttavia è ormai accertato (ford & pedley, 1996 cum bibl.). che in queste differenti condizioni deposizionali, i fattori chimico-fisici, biologici, climatici e le condizioni geomorfologiche vengono registrate nei carbonati da litologie diverse con caratteri propri. ne deriva che l’uso di un unico e generico nome di “travertino”, per indicare depositi formati in situazioni deposizionali così differenti, porta ad una grossa perdita di informazione. in questo contesto si ritiene opportuna una revisione del termine “travertino”, così come è stato finora usato nella terminologia italiana e, tenendo conto delle possibilità di un migliore scambio con la comunità scientifica, un suo adeguamento agli standard internazionali. 2. conoscenze generali i calcari concrezionari sono costituiti principalmente da carbonato di calcio (caco3) sotto la forma minerale calcite e, più raramente aragonite. la loro composizione geochimica dipende dalla composizione chimica delle acque da cui precipitano, che a sua volta deriva dalle condizioni della circolazione sotterranea. infatti le acque di origine meteorica che penetrano nel sottosuolo, possono acquisire ioni per dissoluzione delle rocce carbonatiche e/o solfatiche nella zona vadosa di un sistema carsico oppure circolare in profondità, riscaldarsi in funzione del locale gradiente termico, e tornare in superficie lungo faglie e fratture. queste acque, oltre agli ioni calcio, possono anche contenere quantità variabili di elementi in tracce quali ferro, manganese, stronzio e zolfo a seconda della natura delle rocce dissolte. la formazione dei calcari concrezionari avviene con un processo chimico reversibile che induce la precipitazione del carbonato di calcio per degassazione delle acque arricchite in ioni calcio (ca2+) (herman & lorah, 1987) e conseguente ritorno dell’anidride carbonica (co2) nell’atmosfera. la degassazione, e di conseguenza la deposizione del caco3, è controllata da una complessa interazione di fattori inorganici ed organici, alcuni dei quali non ancora completamente esemplificati (herman & lorah, 1988; julià, 1983). fra i fattori inorganici, di natura essenzialmente fisica, sono di fondamentale importanza le variazioni della pressione parziale della co2 e della temperatura delle acque. anche la turbolenza e la vaporizzazione dell’acqua, indotta dai dislivelli morfologici come avviene in corrispondenza di una cascata, possono localmente essere determinanti per la precipitazione del calcare. fra i fattori organici è da ricordare il ruolo degli organismi vegetali che sottraendo dalle acque la co2 necessaria per il processo di fotosintesi e la produzione di carboidrati, possono anche innescare la precipitazione di caco3. per quanto riguarda l’interazione fra i cianobatteri e la precipitazione della calcite sia in acque calde sia in acque fredde, è tuttora in discussione il ruolo attivo o passivo di questi organismi (golubic et al.,1993; folk,1994; guo et al., 1996; pentecost & whitton, 2000; riding, 2002). in generale, comunque, le cause abiotiche e biotiche operano spesso nella stessa direzione con la produzione di calcari concrezionari, ma è chiaro che il loro contributo relativo varia in funzione del tipo di ambiente di sedimentazione. infatti la precipitazione di carbonato di calcio appare essere prevalentemente inorganica nelle vicinanze di sorgenti idrotermali, dove le condizioni chimico-fisiche limitano il proliferare della vita. allontanandosi da queste, tali condizioni cambiano progressivamente fino ad arrivare ad ambienti palustri o fluviali dove le caratteristiche chimico-fisiche delle acque favoriscono la colonizzazione biologica e quindi prevale la precipitazione bioindotta (violante et al., 1994). 3. classificazioni dei carbonati continentali incrostanti i primi autori in italia che hanno studiato con qualche dettaglio i carbonati continentali, da loro indistintamente denominati “travertini”, ne hanno individuato i caratteri giaciturali, e genetici (boni & colacicchi, 1966), o mineralogici e geochimici (contenuto in stronzio e residuo insolubile; cipriani et al. 1972; 1977; caboi et al., 1991) oppure geochimico-isotopici (elementi maggiori e minori,δ13c e δ18o: per esempio: fritz, 1965; gonfiantini et al., 1968; manfra et al., 1976; turi, 1986; bellanca et al., 1991). la prima classificazione organica, basata sui caratteri tessiturali dei calcari continentali dell’italia meridionale deposti prevalentemente da acque a temperatura ambiente, è stata effettuata da buccino et al. (1978) e integrata ed ampliata in successivi lavori (d’argenio et al., 1983; ferreri 1985; brancaccio et al., 1986; d’argenio & ferreri 1988; violante et al., 1996) (fig. 1) . l’utilità di tale classificazione è stata riconosciuta oltre che dagli autori italiani (carrara, 1998; fioraso, 1999) anche a livello internazionale (pedley, 1990, ford & pedley, 1996). i depositi carbonatici derivati da acque idrotermali non sono stati ancora oggetto di una classificazione sistematica. tuttavia i risultati delle prime indagini effettuate su depositi antichi e tuttora in formazione a rapolano terme (guo & riding, 1992; 1994; 1998; 1999), tivoli (chafetz & folk, 1984.), viterbo zitelle (folk, 1994), bagno vignoni (pentecost, 1994), mostrano che questi depositi possiedono caratteristiche litologiche diverse e ben distinguibili rispetto a quelle dei carbonati originati da acque “fredde”. tra le litofacies distinte da guo & riding (1998), le facies di shrub, crystalline crust, paper-thin raft, coated bubble sembrano essere esclusive di depositi connessi all’attività termale. alcune di queste infatti sono state segnalate anche da altri autori nei carbonati termali di tivoli e rapolano terme (folk et al., 1995), in quelli di canino (carrara, 1994) ed in colorado (usa) (chafetz et al., 1991). queste due classificazioni mettono in risalto le differenze esistenti tra i caratteri tessiturali dei carbonati continentali di acque fredde e di acque calde e contengono solo alcune litofacies che possono essere ritenute tra loro comparabili, rispettivamente i travertini fitoermali, fitoclastici e le sabbie calcaree (d’argenio et al., 1983) e i reed travertine e i lithoclast travertine (guo & riding, 1998), con queste ultime che possono essere considerate di transizione tra un sistema deposizionale e l’altro. differenze che sono state riconosciute anche da molti autori (chafetz &folk, 1984; pedley, 1990; viles & goudie, 1990; koban & schweigert, 1993; pentecost & viles 1994; pentecost, 1995; ford & pedley 1996; glover e robertson, 2003) e che utilizzano in conseguenza una nomenclatura specifica, basata sui caratteri genetici di questi due tipi di depositi (fig. 2). 4. nomenclatura internazionale nella recente letteratura anglosassone il termine italiano “travertino” trova la sua controparte in travertine, ma non mantiene la molteplice valenza ambientale che gli viene attribuita nella letteratura italiana. infatti questo viene di preferenza riferito ai sedimenti carbonatici prodotti nelle vicinanze di sorgenti idrotermali e con fabric primario cristallino (ford & pedley, 1996; riding, 2002). per quanto riguarda i carbonati continentali non termali, derivati cioè da acque di origine sia fluvio-palustri sia di sorgente carsica, nella letteratura anglosasso275i “travertini” in italia ... fig. 2 diagramma delle relazioni genetiche fra i differenti tipi di carbonati continentali, secondo koban & schweigert (1993). the different types of continental carbonates and their genetic relationships according to koban & schweigert (1993). fig. 1 schemi delle caratteristiche tessiturali riconosciute da d’argenio & ferreri (1988) nei carbonati continentali di acque a temperatura ambiente. textural classification of ambient water continental carbonates (after d’argenio & ferreri 1988). 276 ne viene oggi principalmente utilizzato il termine calcareous tufa o tufa (ford & pedley, 1996; pedley, 1990), che deriva dalla parola latina “tophus” con cui plinio indicava materiali da costruzione (calcarei o vulcanici) teneri e di facile estrazione (ford & pedley, 1996; julià, 1983). questo nome include una varietà di termini (kalktuff in tedesco, tuf calcaire in francese) tendenti a sottolineare l’origine di questi depositi da acque a temperatura ambiente per differenziarli da quelli originatisi da acque termali. si sottolinea, comunque, come tale terminologia non è accettata né utilizzata globalmente. infatti sempre nella letteratura anglosassone, è stata proposta una nomenclatura alternativa per la distinzione genetica dei carbonati continentali (pentecost, 1995; pentecost & viles, 1994) che prevede il termine di thermogene travertine per i depositi formatisi in acque idrotermali, mentre con meteogene travertine vengono indicati i depositi originati da acque a temperatura “ambiente”. inoltre la stessa molteplice accezione genetica della parola “travertino” è presente, come in italia, anche in parte della letteratura relativamente recente francese, americana e spagnola (lang et al., 1992; demicco & hardie, 1994; martìn-algarra et al., 2003). 5. caratteri litologici-petrologici dei carbonati continentali lo studio delle litofacies e delle associazioni di facies dei depositi carbonatici attualmente in formazione presso sorgenti termali o presso sorgenti carsiche e negli associati sistemi fluvio-palustri, evidenzia una serie di caratteri esclusivi, che permettono di distinguere due gruppi di depositi corrispondenti i primi ai travertini e gli altri ai calcareous tufa. 5.1. travertini – i carbonati continentali di origine idrotermale il termine travertino deriva dal latino lapis tiburtinus o “pietra di tivoli”, città alle porte di roma dove questo materiale è stato largamente estratto fin dai tempi dei romani per l’edilizia dell’urbe. il travertino/travertine, in senso stretto, è una roccia caratterizzata da facies laminari compatte, formate da cristalli di calcite anche molto sviluppati (chafetz & folk, 1984) e, in minor quantità, da lamine microcristalline, organogene e granulari o fangose, generalmente più porose (fig. 3). l’estensione laterale degli affioramenti è molto variabile e gli ambienti deposizionali rappresentati mostrano una limitata diversità (ford & pedley, 1996). in generale i depositi calcarei riferibili al travertino sono scarsamente influenzati dai fattori climatici, presentano tassi di accrescimento anche elevati e scarsità di organismi vegetali superiori (fig. 4). dal punto di vista geochimico, presentano di norma un debole arricchimento in c13, alti contenuti in carbonio inorganico disciolto totale (tdic), magnesio, stronzio (cipriani et al., 1972; pentecost & viles, 1994; pentecost, 1995; ford & pedley, 1996) e zolfo (turi, 1986). fig. 3 aspetto tipico del travertino deposto in corrispondenza delle sorgenti idrotermali di bagnarello di tolfa (roma) a sinistra, e dell’acqua borra (siena) a destra. typical travertine lithofacies at the hydrothermal spring of bagnarello di tolfa (roma) left, and at acqua borra (siena) right. e. capezzuoli & a. gandin 277 benchè la caratterizzazione petrologica del travertino non sia stata ancora approfondita, e in particolare le ricerche sulla sua diagenesi siano poco sviluppate (love & chafetz, 1988; 1990; chafetz & guidry, 2003), il risultato delle ricerche effettuate sui depositi antichi e quelli tuttora in formazione presso le sorgenti idrotermali di rapolano terme (chafetz & folk, 1984; folk et al.,1985; barazzuoli et al., 1988; guo & riding 1998; 1999; gandin et al., 2002) mostrano che i travertini, intesi come depositi che si formano da acque calcaree calde nelle immediate vicinanze di un complesso idrotermale, hanno fabric specifici, caratteristici dei vari microambienti deposizionali. i diversi litotipi distinti (crystalline crust, shrub, paper-thin raft, coated bubble, pisoid, lithoclast, reed travertine; guo & riding, 1998) e le diverse associazioni di facies riconosciute, sono caratteristici, essenzialmente di due ambienti deposizionali (ford & pedley, 1996) che spesso interagiscono e si alternano tra loro: a) dorsali di travertino corrispondono a risorgenze lineari più o meno rettilinee lungo faglie e fratture del terreno, dove le acque termali ed i gas sotterranei risalgono e scaturiscono in superficie. qui il carbonato di calcio precipita formando inizialmente piccoli coni che successivamente per coalescenza, creano dorsali di travertino più o meno estese e più o meno elevate, a seconda della velocità di precipitazione e della durata dell’attività della sorgente. nel caso di sorgenti puntiformi si formano veri e propri pinnacoli di travertino. a rapolano terme esiste uno dei più importanti e tra i più studiati esempi di dorsale di travertino al mondo (terme di san giovanni; guo & riding, 1992, 1994, 1998, 1999) (fig.4). b) terrazzi il fluire delle acque calde che si allontanano dalla sorgente ne provoca un graduale raffreddamento con conseguente precipitazione del carbonato di calcio in corrispondenza degli ostacoli presenti sul percorso. si formano così dighe e barriere che individuano pozze di varia misura (anche millimetriche) fino a piscine di acqua termale (fig. 4). da queste prime si dipartono una serie di vasche sussidiarie a quote inferiori che solitamente si allargano a ventaglio da quella principale. la maggiore o minore altezza del complesso consente l’eventuale sviluppo di cascate, microterrazze e canali sospesi. caratteristica comune di questi edifici travertinosi è la totale assenza di vegetazione superiore nelle immediate vicinanze della zona di deposizione (fig. 4). gli esempi più imponenti si trovano negli stati uniti (parco di yellowstone: fouke et al. , 2000 cum bibl. ) e in turchia (pamukkale, altunel & hancock, 1993). 5.2. calcareous tufa i carbonati continentali di acque fredde le località di affioramento dei depositi derivati da acque a temperatura ambiente o fredde risultano essere più numerose di quelle dei carbonati di acque termali, come pure, di norma è maggiore l’estensione laterale (ford & pedley, 1996). gli ambienti deposizionali, compresi in sistemi fluvio-palustri, sono diversificati e si susseguono lateralmente in maniera continua e casuale, anche a causa dello sviluppo di floride comunità vegetali e animali che determinano modificazioni geomorfiche, spesso rilevanti, lungo il percorso delle acque (violante et al., 1996). la roccia che si deposita è normalmente caratterizzata da una poco evidente stratificazione e da un’alta porosità (fig. 5). ambedue le caratteristiche sono da mettere in relazione alla incrostazione in posto di piante palustri, di accumuli disordinati di frammenti di steli oppure di batteri, alghe e briofite che formano concrezioni laminari. la classificazione di queste litofacies e dei relativi caratteri tessiturali è dovuta a buccino et al. (1978), i quali riconoscono varie facies: fitoclastica e bibliolitica, fitoermale, stromatolitica e sabbie calcaree. successivamente sono state definite le associazioni di litofacies collegate con i differenti sub-ambienti: lacustre-palustre, palustre, di pendio poco acclive, di pendio acclive, di gradinata di vasche, di cascata (d’argenio et al., 1983; ferreri 1985; brancaccio et al., 1986; d’argenio & ferreri 1988). in letteratura sono state proposte altre classificazioni, solo in parte derivate da quella di buccino et al., (1978), basate sulle caratteristiche sedimentologico-petrologifig. 4 esempi di ambienti deposizionali dei travertini: dorsale presso le terme di san giovanni (rapolano terme, siena) a sinistra; complesso di terrazzi presso le sorgenti termali di pamukkale (turchia) a destra. si noti la caratteristica assenza di vegetazione. examples of travertine depositional systems: left mound near the thermal spring of san giovanni (rapolano terme, siena); right – terrace complex near the thermal springs of pamukkale (turkey). notice the characteristic absence of vegetation. i “travertini” in italia ... 278 che di questi depositi (viles & goudie, 1990; pentecost & viles, 1994; pentecost, 1995; ford & pedley, 1996). altri criteri di classificazione dei calcareous tufa sono basati su parametri di tipo fisiochimico e biochimico (geurts, 1976), geomorfologico (symoens et al., 1951), botanico (pentecost & lord, 1988) e sulle associazioni di facies e ambienti di deposizione (ordoňez & garcia del cura; 1983; pentecost, 1995; ford & pedley, 1996) (fig. 6). in generale, comunque, tutti gli autori concordano sul fatto che la loro formazione è strettamente dipendente dalle condizioni climatiche, con tassi di deposizione di norma bassi. i caratteri petrografici sono stati illustrati da vari autori (irion & müller, 1968; braithwaite, 1979; love & chafetz, 1988; lang et al., 1992; violante et al., 1994 cum bibl.), ma non esiste ancora una classificazione sistematica. geochimicamente essi possiedono una bassa concentrazione di tdic circa in equilibrio con l’atmosfera del suolo, scarsi contenuti di stronzio, magnesio e un accentuato impoverimento in c13 (pentecost & viles, 1994; pentecost, 1995; ford & pedley, 1996). va sottolineato come i calcareous tufa si possano trovare anche associati ai travertini dei quali possono rappresentare la naturale continuazione laterale. infatti essi si formano anche da acque di origine idrotermale le cui condizioni chimiche-fisiche, per diluizione, raffreddamento e depletamento, sono diventate accessibili per la colonizzazione da parte di piante superiori (ford & pedley, 1996). in generale ai calcareous tufa corrispondono tre tipi di ambienti deposizionali: 1) fiumi lungo i corsi d’acqua la precipitazione di carbonato di calcio dà origine a depositi prevalentemente fitoclastici, associati a livelli sabbiosi derivati dall’ulteriore frammentazione dei fitoclasti da parte delle correnti fluviali. localmente, in corrispondenza di sbarramenti (fig. 6), si possono formare dighe calcaree (sbarramento delle marmore; carrara et al., 1995; mai maikden in etiopia: berakhi et al., 1998), costituite da depositi fitoermali, bioerme algali e stromatoliti, con lo sviluppo verso monte di laghi anche molto estesi come nel caso di plitvice, in croazia (emeis et al., 1987 cum bibl.). 2) sorgenti sospese, terrazzi e cascate – di solito i calcareous tufa si sviluppano vicino alla sorgente come terrazzi solitamente lobati (perched springline: pedley et al., 2003) o al piede della rottura di pendio (cascate). nelle aree frontali dei terrazzi, i lobi, generalmente molto acclivi, sono intensamente colonizzati da alghe, muschi ed epatiche (briofite) che formano cospicue strutture fitoermali e microermali. 3) laghi e paludi ai margini dei bacini lacustri e nelle zone poco drenate si formano stagni o paludi intensamente colonizzati da macrofite, briofite alghe e batteri. si formano quindi calcareous tufa composti da bioerme algali, biblioliti, stromatoliti e sedimenti fitoclastici (carrara 1998; glover & robertson, 2003). talora in condizioni climatiche particolarmente umide, la quantità di vegetazione è tale che fig .5 esempi tipici di calcareous tufa a) facies fitoermali e b) cuscini di briofite presso poggibonsi (siena); c) piscine e piccole cascate lungo il fiume elsa presso colle val d’elsa, (siena). examples of typical calcareous tufa: a) phytohermal facies and b) briophyte pillows near poggibonsi (siena); c) pools and small falls along the elsa river near colle val d’elsa (siena). e. capezzuoli & a. gandin in parte non viene incrostata per cui si formano accumuli di materia organica che con il tempo tende a carbonizzare (torba). 6. il significato geologico e ambientale dei carbonati continentali le sorgenti termali e le relative acque calcaree che formano i travertini devono la loro origine a sistemi di faglie attraverso le quali le acque meteoriche discendono in profondità, si scaldano sia per gradiente geotermico o per l’attraversamento di aree con gradiente geotermico anomalo, sciolgono i sali della roccia incassante che depositano risalendo in superficie (minissale, 1991). la genesi dei calcareous tufa invece appare strettamente legata a fattori climatici, in quanto il carbonato disciolto ha origine principalmente dai suoli e dai connessi fenomeni di carsismo (goudie et al., 1993; pentecost, 1995). dal punto di vista applicativo, il riconoscimento delle condizioni genetiche dei carbonati continentali apporta informazioni immediate, utili per ottenere ricostruzioni paleogeografiche ed effettuare, oltre alle normali interpretazioni sedimentologico-stratigrafiche, anche ricostruzioni tettoniche (hancock et al., 1999), mentre i calcareous tufa possono essere diagnostici dell’andamento climatico di un’area e dell’impatto antropico verificatosi nel recente passato (goudie et al., 1993; cilla et al., 1994; andrews et al., 1997; dramis et al., 1999). 7. proposta per la nomenclatura in italia solo recentemente anche nella letteratura italiana si inizia a riconoscere il dualismo presente all’interno del termine “travertino”. in alcuni articoli riguardanti i carbonati continentali, è stata adottata una terminologia genetica che tende a distinguere le facies calde (hot water-acque calde-thermal water travertine) da quelle fredde (ambient water-acque a temperatura ambientecold water travertine) (violante et al. 1994; violante et al., 1996; d’argenio 2001), mentre minissale et al., (2002) utilizzano la nomenclatura meteogene/thermogene travertine proposta da pentecost (1995). allo scopo di unificare la terminologia italiana a 279 fig. 6 schema di classificazione dei calcareous tufa in funzione del fabric da: ford & pedley (1996). classification of the calcareous tufa on the basis of fabric type. after ford & pedley (1996). i “travertini” in italia ... quella internazionale e quindi di rendere più facile la comunicazione scientifica con l’immediata correlazione tra appellativo usato, roccia e sistema deposizionale, si propone l’uso di due diversi termini per indicare questi due diversi tipi di carbonati continentali. la parola travertino, nata per indicare i calcari che si formano intorno alle sorgenti calde di tivoli, dovrebbe designare esclusivamente i depositi di origine idrotermale, mentre per indicare i carbonati precipitati da acque fredde, a temperatura ambiente in sistemi fluvio-palustri alimentati da sorgenti di acque calcaree, si ritiene che calcareous tufa, in diretta correlazione con la lingua latina anche se “re-inventato” dalla letteratura anglosassone, sia il termine più adeguato. l’italianizzazione del termine calcareous tufa in “tufa calcareo” è sconsigliabile per due ragioni: la prima perché la comunicazione scientifica oggi si effettua essenzialmente in inglese, la seconda per evitare confusioni con la dizione “tufo calcareo” che è entrata nell’uso comune in puglia per indicare una formazione calcarenitica marina pliocenica molto utilizzata nell’edilizia locale (caputo et al., 1996; cherubini et al., 1996; m.tropeano com. pers.). per la stessa ragione è sconsigliabile il termine “tufa”, abbreviativo di calcareous tufa nella terminologia anglosassone, che può essere confuso con la parola “tufo” classicamente usato per caratterizzare i sedimenti vulcanici piroclastici. per l’individuazione dei due tipi di carbonati, le caratteristiche generali suggerite da pentecost (1995) e ford & pedley (1996), e condensate in questo studio possono costituire una valida base di differenziazione. tuttavia, poiché le conoscenze e i dati a nostra disposizione sulla genesi dei travertini, dei calcareous tufa e di tutti i termini intermedi sono ancora limitati e non sono stati ancora esaurientemente illustrati i caratteri petrologici distintivi delle numerose litofacies, la nomenclatura qui proposta potrà essere verificata in futuro sulla base di un maggior numero di dati sia chimico-isotopici sia, e soprattutto, di tipo petrografico. 8. problematiche connesse e implicazioni paleoambientali allo stato attuale delle conoscenze, è evidente come non sia facile contenere tutte le molteplici variazioni di facies, di ambiente e di deposizione dei carbonati concrezionari all’interno di un semplice schema. molte delle definizioni fondamentali necessarie per una classificazione rigorosa sono tuttora in discussione. un esempio è fornito dalla definizione di sorgente calda, concetto necessario per la distinzione fra carbonati concrezionari “caldi” e “freddi”. esistono molte classificazioni delle acque in base alla temperatura (es. desio, 1973; celico, 1986); la più recente distinzione effettuata da pentecost et al. (2003) prevede la temperatura di 36.7 c° come limite fra le due classi, ma gli stessi autori raccomandano che i termini caldo e freddo siano sempre accompagnati dal criterio utilizzato per la loro definizione e dal range della temperatura delle acque. allo stesso modo essi pongono l’attenzione sull’uso dell’aggettivo ambiente per caratterizzare le acque con una temperatura simile a quella dell’atmosfera in corrispondenza della sorgente, ritenendolo un termine ambiguo, perché strettamente connesso alla latitudine/clima dell’area e quindi non utilizzabile per correlazioni globali. uno dei maggiori problemi nella realizzazione di una distinzione estremamente schematica dei carbonati concrezionari, è sicuramente legato alla naturale transizione che esiste fra quelli caldi e quelli freddi. infatti è evidente come in questi casi, in cui facies calde evolvono lateralmente a quelle fredde in funzione di variazioni chimiche-fisiche di difficile schematizzazione e variabili da caso a caso, la distinzione risulta molto complessa se non nei loro termini estremi. questi ultimi, infatti, sono sicuramente identificabili sul terreno, per cui la definizione dei termini intermedi può essere compiuta con maggiore dettaglio in laboratorio con l’ausilio di analisi petrografiche, geochimiche e isotopiche. in sostanza la differenziazione dei travertini dai calcareous tufa può essere effettuata in base alle caratteristiche generali del litotipo (porosità, contenuto organico, fabric, caratteristiche geochimiche…) e tenendo comunque presente che fattori locali possono anche influenzare le caratteristiche tessiturali e/o geochimiche dei singoli litotipi. 9. discussione tra i carbonati continentali deposti da acque sorgive, i calcareous tufa sono stati oggetto, come già detto, di una embrionale caratterizzazione petrografica, mentre per i travertini non esiste ancora una analisi approfondita. tuttavia i risultati delle sporadiche ricerche fin’ora condotte suggeriscono la possibilità di distinguere i travertini dai calcareous tufa in funzione del loro fabric deposizionale (fig. 7). ne consegue che, adottando criteri che tengano conto dei caratteri tessiturali e geochimici di sedimenti attualmente in formazione, potrà essere effettuata la distinzione genetica dei carbonati continentali antichi. eventuali future ricerche potranno apportare ulteriori integrazioni a questa classificazione. comunque per il momento l’uso comune di una nomenclatura differenziata dei depositi calcarei concrezionari può portare ad una caratterizzazione genetica del litotipo più immediata e quindi fornire informazioni specifiche di tipo geologico e climatico. infatti, a seconda dalla presenza di travertini o calcareous tufa, le informazioni derivanti sono differenti: nella sedimentologia e stratigrafia, dove i calcareous tufa risultano in genere essere tra i migliori recorder di caratteristiche paleoambientali e paleoclimatiche (henning et al., 1983; carrara et al., 1998); nella geologia strutturale, visto che i travertini sono considerati utili indicatori per la comprensione dei processi e della storia neotettonica (minissale, 1991; hancock et al., 1999); nel campo dell’archeologia e antropologia, che utilizzano le informazioni fornite dai calcareous tufa per la ricostruzione dell’impatto umano sul territorio (cilla et al., 1994; goudie et al., 1993; violante & d’argenio, 2000); nel reperimento di materiali ornamentali, nell’archeometria, e nella conservazione dei monumenti lapidei, poiché soprattutto i travertini costituiscono una delle pietre più usate come ornamento o rifinitura nelle 280 e. capezzuoli & a. gandin costruzioni dell’uomo (rodolico, 1965); nella biologia extraterrestre in quanto i travertini sono oggetto privilegiato di investigazione (nasa, 1995; allen et al., 2000; bishop et al., in press) per la ricerca di vita su marte. ringraziamenti: gli autori ringraziano vivamente claudio carrara per le costruttive osservazioni. lavoro eseguito con i fondi della “quota servizi per la ricerca” dell’università di siena (par 2003, a.gandin) lavori citati allen c.c., albert f.g., chafetz h.s., combie j., graham c.r., kieft t.l., kivett s.j., mckay d.s., steele a., tauton a.e., taylor m.r., thomaskeprta k.l & westall f. 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(1994) – quaternary travertines at rocchetta a volturno (isernia, central italy). facies analysis and sedimentary model of an organogenic carbonate system. i.a.s. 15th reg. meet., april, 1994, ischia, guide book to the field trip, 3-23. 284 ms. ricevuto l’11 maggio 2004 testo definitivo ricevuto il 7 luglio 2004 ms. received: may 11, 2004 final text received: july 7, 2004 e. capezzuoli & a. gandin imp.bini_zuccoli prime note sul rilevamento dell'anfiteatro del garda: metodi e unità provvisorie alfredo bini & luisa zuccoli dipartimento di scienze della terra, università degli studi di milano, via mangiagalli 34, 20133 milano; alfredo.bini@unimi.it riassunto: bini a. & zuccoli l., prime note sul rilevamento dell’anfiteatro del garda: metodi e unità provvisorie. (it issn 0394-3356, 2004). l'anfiteatro del garda mostra alcuni caratteri peculiari, sia petrografici sia geomorfologici, diversi da quelli che si osservano negli altri apparati alpini, per cui è sempre risultato difficile separare le cerchie moreniche sulla base della classica suddivisione in glaciazioni del quaternario alpino. il principale problema di questo anfiteatro è quello della attribuzione delle diverse cerchie moreniche riguardo al quale le opinioni dei vari e numerosi autori sono contrastanti. i dati del presente rilevamento non sono direttamente confrontabili con quelli degli autori citati in quanto è diverso il linguaggio e non esiste alcun sistema per passare da uno all'altro senza equivoci ed incertezze. il würm degli autori precedenti non coincide con il concetto di lgm attualmente in uso. il würm degli autori comprende probabilmente più glaciazioni nel senso di richmond (1986). in assenza di paleosuoli diffusi, i parametri che sono stati utilizzati per riconoscere le unità sono stati: l'alterazione e il colore del colluvio, lo spessore del calcrete, la geometria dei depositi. benchè il colluvio sia costituito da depositi di colate che hanno spesso rimescolato il materiale originario proveniente da unità diverse esistono particolari situazioni, molto diffuse in anfiteatro, in cui il colluvio proviene solo da una unità, omogenea dal punto di vista sedimentologico, o, meglio, da una sola morena. tenendo conto di queste situazioni esiste un "gradiente di caratteristiche" del colluvio andando dalle rive del lago (unità più recenti), alle unità più antiche. la presenza o l'assenza del calcrete sommitale, così come il suo spessore, sono parametri determinanti sul garda. il calcrete è presente su tutte le unità ad esclusione dell'unità più interna (alloformazione del garda) che ne è completamente priva e che perciò è lo lgm. muovendosi verso l'esterno il calcrete aumenta rapidamente di spessore sino ad interessare l'intera massa dei depositi delle unità. sono state così riconosciute varie unità alloe litostratigrafiche, di cui otto sono costituite da till e rappresentano qundi glaciazioni distinte. abstract: bini a. & zuccoli l., geological survey in the garda moraine amphitheatre: methods and preliminary units (it issn 03943356, 2004). the garda glacial amphitheatre shows some peculiar geomorphological and petrographical features, which differ from those of the other alpine glacial amphitheatres. therefore it has been always difficult to separate the end moraines based on the traditional classification of the quaternary alpine glaciations. the most debated topic regarding the characterisation of the garda amphitheatre, is the correlation among the different end moraines, about which there is no agreement in literature. the results of the survey presented here are not comparable with the data by the previous authors, because different concepts and terminology are used and a conversion to older stratigraphic concepts is not available. for instance the term würm is not coincident with the lgm concept, which is in use at present. the würm auct. includes probably more glaciations (sensu richmond, 1986). if no widespread palesoils are available, other parameters are used to identify the different units, such as weathering and colour of colluvium, thickness of calcretes, geometry of depositional units. the colluvial deposits derive from flows which often mix materials from different sources; nonetheless in a lot of situations, within one amphitheatre, colluvium derives from one single unit, with own sedimentological features, or from a single moraine. taking into account these situations there is a continuum of variations of the features of colluvial deposits, moving from the youngest units (close to the lake shores) to the eldest ones. in the garda amphitheatre, presence or absence of calcrete, and its thickness, represent discriminant features. calcretes are present above all the depositional units, but the most internal one (garda alloformation), which represents the lgm. thickness of calcretes increases systematically moving towards the external sector of the amphitheatre, whose units are therefore completely cemented. in this way several alloand lithostratigraphic units could be recognised, eight of which are formed by tills and therefore represent different glaciations. parole chiave: anfiteatro morenico, morene, colluvio, calcrete, garda keywords: moraine amphitheatre, moraine, colluvium, calcrete, garda il quaternario italian journal of quaternary sciences 17(2/1), 2004, 333-342 introduzione l'anfiteatro del garda, sin dagli albori della teoria glaciale, è uno dei più noti al mondo; infatti, solo per fare un esempio, se si cerca la sottovoce moraine amphitheatres nella encyclopedia of geomorphology di r.w. fairbridge edita da dowden, hutchinson & ross inc. del 1968 si trova citato come unico esempio il garda e una carta dell'anfiteatro del garda si trova alla voce laghi. non stupisce quindi che numerosi ricercatori si siano via via interessati al suo studio. poichè questo anfiteatro mostra alcuni caratteri peculiari, sia petrografici sia geomorfologici, diversi da quelli che si osservano negli altri apparati alpini, è sempre risultato difficile separare le cerchie moreniche sulla base della classica suddivisione in glaciazioni del quaternario alpino. dopo aver rilevato direttamente gli anfiteatri del verbano, del lario e dell'iseo e discusso con coloro che hanno rilevato gli anfiteatri tilaventino e di rivoli torinese, appurato che la metodologia messa a punto in tutti questi anni è valida sia per la cartografia sia per la ricostruzione della storia geologica, si è iniziato il rilevamento dell'anfiteatro del garda con criteri moderni a partire dall'area occidentale all'incirca fra salò e esenta a sud di lonato (fig. 1). 334 a. bini & l. zuccoli il problema dell'età delle cerchie moreniche il principale problema dell'anfiteatro è quello dell'attribuzione delle diverse cerchie moreniche. la letteratura abbonda di lavori eseguiti sulla base di osservazioni generali o di studi dettagliati di singole sezioni estrapolati a tutto l'anfiteatro. gli unici rilevamenti geologici completi sono stati quelli di cozzaglio (1933; 1934a; 1934b; 1939) e di venzo (1957, 1961, 1965). quello che penck e bruckner (1909) hanno considerato riss, viene considerato mindel da venzo e il würm dei due autori transalpini, riss da venzo nel 1957 e würm nel 1961 poi ancora riss nel 1965 al termine dei rilevamenti. il würm di cozzaglio diviene riss per venzo (1957 e 1965): anche le numerose sovrapposizioni di würm sul riss, indicate da cozzaglio sul suo fo peschiera, sono inesistenti. si tratta del consueto fenomeno di erosione e dilavamento del paleosuolo rossiccio del riss, cosicchè affiorano le sottostanti ghiaie bianche di aspetto würmiano, ma di età sempre rissiana, come tutte le grandi cerchie. ... i grandi cordoni morenici del tratto orientale da s. zeno di montagna a pastrengo, si presentano ghiaiosi, bianchi e con versanti piuttosto ripidi, a morfologia giovanile. i lembi di paleosuolo rossastro-bruno del riss, giallastri se erosi del terreno più superficiale, sono ridotti ad esigui affioramenti solo all’ esterno ed in basso ai cordoni. basandosi sui lembi di paleosuolo in genere colluviati venzo (1965) pone il würm a ridosso del lago in posizione più interna rispetto al suo lavoro del 1957: di conseguenza il würm, ancora più interno, risulta glaciazione oltremodo ridotta. esso è testimoniato solo dalle ultime e più basse cerchie che orlano il lago; sbarrandolo verso sud. lo stadio würm iii ... è probabilmente arretrato di qualche decina di chilometri entro il lago. ... l’esiguità della glaciazione wiirmiana rispetto alla rissiana, risulta fenomeno generale a sud delle alpi... habbe (1969) critica il metodo di venzo e cozzaglio e, su base puramente morfologica, attribuisce il riss di venzo (1957 e 1965) al würm. cremaschi (1987), sulla base dello studio di alcune sezioni in tutto l'anfiteatro, fig. 1 foto da satellite dell'anfiteatro del garda e area interessata dallo studio. satellite image of the garda amphitatre and study area. considera pleistocene superiore il riss di venzo. il problema centrale risiede nell'età della cerchia più evidente che, nell'area interessata dal presente lavoro, coincide con il monte forca monte soffiano monte nuvolo monte malocco e che coincide con la cerchia di solferino. per venzo è rissiana, per habbe è würmiana, per cremaschi è pleistocene superiore. i dati del presente rilevamento non sono direttamente confrontabili con quelli degli autori citati in quanto è diverso il linguaggio e non esiste alcun sistema per passare da uno all'altro senza equivoci ed incertezze. in ogni caso, tale cerchia è compresa in un'alloformazione che con ogni probabilità è del pleistocene medio e non del pleistocene superiore. il presente lavoro si basa su un rilievo geologico, metro a metro, del territorio e di conseguenza si trova largamente in accordo con venzo (soprattutto 1957). e' stato osservato che all'interno delle cerchie rissiane di venzo sono presenti depressioni occupate da piccoli laghi. si è sostenuto che se i laghi sono ancora presenti le depressioni intermoreniche devono essere recenti e quindi da ascrivere al würm. in realtà, il problema dell'origine delle depressioni va tenuto separato da quello dell'origine dei laghi. non è sufficiente la presenza di una depressione per dare origine ad un lago; è necessario anche che il fondo della depressione sia impermeabile. quindi una depressione intermorenica più antica può ospitare in periodi più recenti un lago che non era presente all'origine perchè il suo fondo è stato successivamente impermeabilizzato. l'impermeabilizzazione può avvenire per accumulo di colluvio proveniente da suoli evolutisi nel tempo sulle morene, oppure per deposizione di loess durante una successiva glaciazione. non si ritiene pertanto che questa osservazione sia valida da un punto di vista geologico. un altro punto da considerare è che il würm degli autori precedenti e dei loro epigoni non coincide con il concetto di lgm attualmente in uso. a partire dai dati di terreno con metodi geologici o, al massimo, geocronometrici è possibile datare solo l'ultima espansione glaciale (lgm) che corrisponde secondo la definizione di richmond (1986), riportata in bini (1997) e in bini et al. (2001)1, all'ultima glaciazione. il würm degli autori comprende probabilmente più glaciazioni nel senso di richmond. poichè non vi sono criteri per collocare nel tempo i depositi glaciali più antichi dell'ultima glaciazione, non è possibile stabilire se le unità riconosciute sul terreno e appena più antiche dello lgm cadano nell'intervallo tempo che gli autori attribuivano al würm. in quest'ottica l'alloformazione del garda è lo lgm; l'alloformazione di puegnago e l'alloformazione di monte san pietro sono solo più vecchie dello lgm, ma non è possibile stabilire se rientrino, o no, nel periodo di tempo che gli autori attribuivano al würm, poichè non esistono metodi oggettivi per datarle. non ha senso 335prime note sul rilevamento ... quindi identificare il würm degli autori con lo lgm. nonostante le critiche che gli sono state rivolte, venzo è stato l'unico ad eseguire un rilievo geologico, che poteva essere condotto con maggior dettaglio già allora con la base cartografica a disposizione, ma che in ogni caso risponde a criteri geologici e non solamente geomorfologici. venzo ha applicato il suo schema delle glaciazioni a priori e perciò non poteva giungere a risultati diversi, ma ha oggettivamente separato la cerchia morenica più interna a causa dei suoi caratteri ben differenti da tutte le altre dell'anfiteatro assegnandola al würm. osserva che mancano il würm 2 e il würm 3 che egli ritiene meno estesi e percio coperti dal lago e osserva inoltre come l'alterazione aumenti nelle cerchie rissiane dalla più interna alla più esterna. ovvero le suddivisioni in unità operate in questo lavoro erano già state osservate da venzo, ma lo schema a priori da lui utilizzato gli ha impedito di riconoscerle apertamente. metodo impiegato nel rilevamento la suddivisione dei depositi presenti in unità allostratigrafiche, negli anfiteatri del verbano, del lario e del sebino, è stata possibile grazie alla presenza di paleosuoli; infatti l'unico modo per distinguere tra loro due corpi sovrapposti di depositi fluviali o glaciali, che abbiano lo stesso bacino di alimentazione, è la presenza di un suolo o comunque di un'alterazione a tetto dell'unità inferiore (richmond, 1962; bini, 1997; bini et al., 2001). nell'anfiteatro del garda i paleosuoli in posto sono rari, ma non del tutto assenti; il rilievo di dettaglio e l'attuale ampliamento dei vigneti hanno permesso, infatti, di osservarne un certo numero, anche se non è sufficiente a servire da marker per il riconoscimento di unità allostratigrafiche. solitamente si rinvengono spesse coltri di colluvio, sovrastanti depositi glaciali o fluvioglaciali che a tetto presentano un calcrete pedogenetico. lo spessore del calcrete è variabile, ma aumenta muovendosi dalle unità più recenti alle unità più antiche. il colluvio è spesso fortemente arrossato, sino a 5yr delle tavole munsell; presenta in molti casi inversione del profilo con la parte più arrossata in basso e quella meno arrossata in alto. anche in questo caso l'arrossamento del colluvio aumenta verso le unità più antiche. la differenza principale tra i depositi dell'anfiteatro del garda e quelli degli altri anfiteatri risiede nel fatto che sul garda i depositi sono costituiti interamente da clasti e da matrice carbonatici, mentre i clasti cristallini sono molto rari. nei suoli questo fatto comporta la formazione di spessi orizzonti calcici nelle unità più recenti e la completa cementazione delle unità più antiche. questi suoli si sono ovviamente formati in condizioni generali di biostasia. quando si è passati a condizioni di resistasia sia per cause naturali, come l'approssimarsi di un ghiacciaio durante una nuova glaciazione, sia per cause antropiche, come il disboscamento, l'aratura o la preparazione del terreno per la coltivazione della vite, l'intero spessore dei suoli si è mosso lungo i versanti per soliflusso o per colate, andando a costituire le coltri colluviali che attualmente si osservano. lo scivolamento del suolo per aumento del contenuto in acqua in condizioni di resistasia è stato facilitato 1"the term "glaciation" is applied here to a specific glacial advance and recession, the deposits of wich are separable from those of other glaciations by evidence of exstensive recession and downwasting of glaciers or by evidence of a warm climate as interpreted from pollen diagrams or weathering profiles. the terms "warm" and "cold" are used here in a very general sense to indicate broad differences in the climate of intervals separating glaciations." 336 ed è stato completo a causa della presenza del sottostante orizzonte calcico. questi, infatti, oltre ad essere praticamente impermeabile e capace quindi di sostenere una falda locale, costituisce una superficie piana, sufficientemente liscia che sui versanti inclinati delle morene ha rappresentato la superficie preferenziale di scivolamento. in assenza di paleosuoli diffusi, i parametri che sono stati utilizzati per riconoscere le unità sono stati: l'alterazione e il colore del colluvio lo spessore del calcrete la geometria dei depositi riguardo all'uso del colluvio come marker, che venzo (1957, 1961, 1965) aveva già utilizzato, è necessario fare alcune precisazioni. 1) il colluvio è costituito da depositi di colate che hanno spesso rimescolato e omogenizzato il materiale originario proveniente da unità diverse dal punto di vista stratigrafico. considerare come marker il colluvio in genere può essere quindi errato. esistono però particolari situazioni, molto diffuse in ambiente di anfiteatro, in cui il colluvio proviene solo da una unità, omogenea dal punto di vista sedimentologico, o, meglio, da una sola morena. la più chiara di queste situazioni, e una delle più diffuse, si ha quando il colluvio affiora pochi metri sotto la cresta di una morena, poichè in questo caso il colluvio può provenire solo dalla cresta. l'esempio tipico è a san pietro sopra polpenazze del garda (fig. 2) dove 2 o 3 metri sotto la cresta, si può descrivere il colluvio con inversione del profilo che rappresenta il suolo sommitale della morena di san pietro. oppure quando si ha una successione di morene di unità diverse, come in fig. 3 dove il colluvio compreso nella valle tra le unità a e b non è significativo, mentre lo è il colluvio sul lato interno della morena dell'unità b. l'insieme di numerose osservazioni di questo tipo, sulla cui validità non si può eccepire, associato alla geometria dei depositi consente di riconoscere e caratterizzare unità differenti. per quanto riguarda invece il colluvio presente sui depositi fluvioglaciali nei sandur si può essere sicuri della provenienza solo se il sandur era alimentato dal ghiacciaio relativo ad una singola unità, come, ad esempio, nella fig. 4 che schematizza la piana di s. tomaso-brodena, a sud di lonato, completamente compresa tra morene dell'alloformazione di san pietro e ben separata dalle morene dell'alloformazione del monte forca. in altri casi, dove l'alimentazione non è sicura, il colluvio su fluvioglaciale non è utilizzabile a fini stratigrafici. 2) indipendentemente da queste considerazioni esiste una variazione graduale delle caratteristiche del colluvio andando dalle rive del lago, in corrispondenza dell'unità più recente, alle unità più antiche, che comprende: il contenuto in argilla, il colore, la presenza di patine e/o noduli di ferro-manganese, la presenza di screziature, la presenza di carbonati e di gusci di gasteropodi terrestri. la presenza o l'assenza del calcrete sommitale, così come il suo spessore, sono parametri determinanti sul garda. il calcrete è presente su tutte le unità ad esclusione dell'unità più interna (alloformazione del garda) che ne è completamente fig. 2 sezione schematica della morena di san pietro. il colluvio affiora pochi metri sotto la cresta della morena e può provenire solo dalla cresta stessa; rappresenta perciò il suolo sommitale della morena di san pietro. schematic cross section of the san pietro moraine. colluvial deposits crop out a few meters below the top of the moraine so that these deposits could only derive from that ridge. consequently the colluvial deposits represent the soil at the top of the san pietro moraine. fig. 3 sezione schematica che mostra una successione di morene di unità diverse. il colluvio compreso nella valle tra le unità a e b non è significativo, mentre lo è il colluvio sul lato interno della morena dell'unità b. schematic section showing a sequence of moraines belonging to different units. the meaning of the colluvial deposits which lie in the valley between units a and b is not clear, but is obvious for the colluvial deposits that lies on the inner side of the moraine belonging to the unit b. a. bini & l. zuccoli 337 fig. 4 carta schematica semplificata della piana fluvioglaciale di s. tomaso brodena, a sud di lonato, completamente compresa tra morene dell'alloformazione di san pietro e ben separata dalle morene dell'alloformazione del monte forca. in figura la piana fluvioglaciale è rappresentata dall'area a righe orizzontali. semplified map of the sandur (horizontally ruled) near san tomaso-brodena, south of lonato. all the sandur lies within the endmoraines of the alloformazione di san pietro and it is completely separeted from the moraines of the alloformazione di monte forca. prime note sul rilevamento ... 338 priva. poichè l'unità appena più esterna (alloformazione di puegnago) presenta sempre un calcrete centimetrico, l'unità priva di calcrete, quindi con un profilo di alterazione completamente diverso, è lo lgm. muovendosi verso l'esterno il calcrete aumenta rapidamente di spessore sino ad interessare l'intera massa dei depositi delle unità. i valori osservati sono qui di seguito riassunti: alloformazione del garda assente alloformazione di puegnago centimetrico alloformazione di monte san pietro 15 ÷ 30 cm alloformazione di monte forca ≥ 1 m alloformazione cementazione discontinua, di monte cervo localmente completa alloformazione di monte serina cementazione completa da ultimo, ma non per importanza, viene la geometria dei depositi. ossia il mezzo di trasporto dei sedimenti, che sia acqua, ghiaccio o vento, depone i sedimenti con una geometria discreta. i depositi al margine di un ghiacciaio non possono avere qualunque andamento, ma riflettono quella che era la forma del ghiacciaio, la sua dinamica, comprendendo con questo termine sia le linee di flusso sia la distribuzione delle zone di ghiaccio stagnante, di ghiaccio caldo e di ghiaccio freddo, e la distribuzione delle acque al margine del ghiacciaio stesso. nel ricostruire l'andamento delle morene e dei corpi geologici bisogna tener conto di queste considerazioni. la geometria dei depositi è l'argomento che consente a venzo (1965) di attribuire al riss anche le morene che nel tratto orientale (1961) aveva attribuito al wurm a causa dei caratteri di alterazione. il fatto che i depositi cambino caratteristiche lungo una medesima morena o un medesimo gruppo di morene è un fatto che si è già presentato in altri anfiteatri, come quello del verbano, dove le morene orientali sottendono depositi cha hanno, per litologia, caratteristiche diverse da quelle dei depositi sottesi dalle morene occidentali. probabilmente un fatto analogo avviene anche nell'anfiteatro del garda e ha tratto in inganno venzo. unità provvisorie nella parte di anfiteatro del garda sinora rilevato, ossia dal monte luzzago a nord di puegnago sino a esenta a sud di lonato, sono state riconosciute le seguenti unità (fig. 5 e 6): alloformazione del garda (ga) l'unità è costituita da depositi glaciali, fluvioglaciali e lacustri. e' considerata come würm-moräne da habbe (1969) e come würm da venzo (1957). la superficie limite superiore è caratterizzata da un suolo spesso circa 50 cm, di colore 2.5y, privo di calcrete. lateralmente alla morena il colluvio, quando presente, è ricco di carbonati e di nicchi di gasteropodi terrestri ed è di colore 2.5y. la superficie limite inferiore è una superficie di erosione. allogruppo di polpenazze (pol) l'allogruppo è stato istituito perchè in alcune aree con scarsità di affioramenti è difficile distinguere le alloformazioni che lo costituiscono (alloformazione di puegnago e alloformazione di monte san pietro). i depositi dell'allogruppo sono considerati come würm-moräne da habbe (1969) e come riss da venzo (1957). il riss di venzo (1957) comprende l'alloformazione di monte forca, l'alloformazione di monte cervo e tutto l'allogruppo di polpenazze, tuttavia venzo sottolinea come l'alterazione delle morene più esterne (m. soffiano) sia maggiore di quelle più interne. alloformazione di puegnago (ppu) si tratta di depositi glaciali, fluvioglaciali e lacustri. la superficie limite superiore è costituita da una superficie di erosione che decapita l'unità della parte superiore pedogenizzata. la decapitazione avviene in corrispondenza del tetto degli orizzonti calcici del suolo per cui molti affioramenti si presentano cementati a tetto per spessori di alcuni centimetri. in alcuni affioramenti è visibile la porzione basale del suolo subito al di sopra dell'orizzonte calcico. i ciottoli, esclusivamente carbonatici, sono alterati e il colore è compreso nella pagina 10yr delle tavole munsell. al di sotto dell’orizzonte calcico i clasti di natura cristallina sono arenizzati e il colore della matrice è compreso nella pagina 10yr delle tavole munsell, più raramente nella pagina 7.5yr. in alcuni affioramenti è presente, a tetto, loess limoso argilloso indurito con patine di ossidi di ferro e manganese di colore 10yr. la superficie limite inferiore è una superficie di erosione che tronca i depositi dell’alloformazione di monte san pietro. alloformazione di monte san pietro (ppi) e' costituita da depositi glaciali, fluvioglaciali, deltizi, lacustri e di versante tipo grèzes litées. la superficie limite superiore è caratterizzata da un suolo che nell'orizzonte bt ha colore da 10yr a 7.5yr e, nell'orizzonte b/c, 10yr. clasti cristallini alterati, parziale alterazione dei clasti carbonatici. orizzonte calcico sempre presente. la presenza di un resto di paleosuolo in alcuni affioramenti, indice di clima caldo, consente di suddividere l'allogruppo di polpenazze nelle due alloformazioni di puegnago e di monte san pietro. nella maggior parte degli affioramenti la superficie limite superiore è costituita da una superficie di erosione che decapita l'unità della parte superiore pedogenizzata. la decapitazione avviene in corrispondenza del tetto degli orizzonti calcici del suolo per cui molti affioramenti si presentano cementati a tetto per uno spessore che giunge sino a 30 cm. la superficie limite inferiore è una superficie di erosione. alloformazione di monte forca (sfo) e' costituita da depositi glaciali e fluvioglaciali. e' considerata come come riss ii (venzo, 1957; 1965) e come würm da habbe (1969). la superficie limite superiore è caratterizzata da un suolo in genere troncato che presenta un colore variabile tra 10yr e 7.5yr. i ciottoli a. bini & l. zuccoli 339 fig. 5 carta schematica semplificata dell'area di anfiteatro studiata. e' riportata la massima estensione delle unità. semplified map showing the maximum extension of the units in the portion of the garda amphiteatre here studied. cristallini sono arenizzati. e' presente un orizzonte cca ben sviluppato tanto da trasformare il diamicton sottostante in diamictite per spessori spesso superiori al metro. la decapitazione avviene in corrispondenza del tetto degli orizzonti calcici del suolo per cui molti affioramenti si presentano cementati a tetto. la superficie limite inferiore è una superficie di erosione. l'alloformazione di monte forca copre i diamicton delprime note sul rilevamento ... l'alloformazione di monte cervo e i loess 7.5yr a tetto di quest'ultima unità. la presenza di un paleosuolo decapitato, ma ricoperto da loess e colluvi e successivamente da ghiaie, testimonia che tra la formazione delle morene di monte serina monte cervo e di monte soffiano si è avuta pedogenesi e quindi un interglaciale, ovvero le due unità, alloformazione di monte cervo e alloformazione di monte forca sono due buone unità, hanno il rango di alloformazioni e rappresentano due distinte glaciazioni. l'unità è coperta dai depositi dell'allogruppo di polpenazze e da colluvi di colore variabile da 10yr a 5yr. i colluvi sono osservabili già alcuni metri al di sotto della cresta della morena di monte forca. alloformazione di monte cervo (sce) si tratta di depositi glaciali. e' considerata come riss i (venzo, 1957; 1965) e come riss da habbe (1969). la superficie limite superiore è una superficie di erosione che tronca il suolo originario. la decapitazione avviene in corrispondenza del tetto degli orizzonti calcici del suolo per cui molti affioramenti si presentano cementati a tetto. lo spessore della cementazione è variabile da alcune decine di centimetri a discontinua che può interessare l'intero corpo osservabile ossia per alcuni metri. essa è coperta da loess e colluvi induriti, screziati di colore 7.5yr. l'unità copre in erosione l'alloformazione di monte serina ed è coperta dall'alloformazione di monte forca (condizioni visibili in affioramento). quest'ultima unità copre anche i loess 7.5yr. la presenza di un paleosuolo decapitato, ma ricoperto da loess e colluvi e successivamente da ghiaie, testimonia che tra la formazione delle morene di monte serina monte cervo e di monte soffiano si è avuta pedogenesi e quindi un interglaciale, ovvero le due unità, alloformazione di monte cervo e alloformazione di monte forca sono due buone unità, hanno il rango di alloformazioni e rappresentano due distinte glaciazioni. i clasti cristallini sono alterati e la matrice presenta colore variabile tra 2.5y e 5yr. alloformazione di monte serina (sse) l'unità è costituita da depositi glaciali e fluvioglaciali. e' considerata come come mindel ii (venzo, 1957; 1965) e come riss da habbe (1969). la superficie limite superiore è costituita da una superficie di erosione che decapita l'unità della parte superiore pedogenizzata. la decapitazione avviene in corrispondenza del tetto degli orizzonti calcici del suolo per cui molti affioramenti si presentano cementati a tetto. lo spessore della cementazione è variabile da alcune decine di centimetri all'intero corpo osservabile ossia per alcuni metri. il suolo parzialmente conservato si osserva, in alcuni affioramenti, coperto dal diamicton dell'alloformazione di m. cervo. la presenza di questo paleosuolo decapitato testimonia che tra l'alloformazione di monte cervo e l'alloformazione di monte serina si è avuta pedogenesi e quindi un interglaciale, ovvero le due unità sono due buone unità, hanno il rango di alloformazioni e rappresentano due distinte glaciazioni. i ciottoli cristallini sono arenizzati o con cortex e la matrice presenta colori 7.5yr e 5yr. l'alloformazione di monte serina copre, in erosione, i conglomerati di cà dell'ava e la formazione di cascina colombera ed è coperta dall'alloformazione di monte cervo, da colluvi di colore 10yr÷7.5yr e da loess di colore 10yr. formazione di cascina colombera (co) unità litostratigrafica costituita dal conglomerato di ca’ dell’ava alterato. a letto l'unità passa gradualmente, con limite ad organi geologici, al conglomerato di ca’ dell’ava, mentre a tetto il limite è erosivo ed è coperto dal colluvio. la formazione di cascina colombera si presenta fortemente alterata, indurita, composta da ghiaie poligeniche immerse in un’abbondante matrice di colore 7.5yr÷10yr, ricca in argilla e limo. i ciottoli si frantumano con facilità. lo spessore dell'unità è variabile per erosione da pochi centimetri a qualche metro. conglomerato di cà dell'ava (ca) e' un'unità litostratigrafica costituita da depositi 340 fig. 6 schema dei rapporti stratigrafici nell'area di anfiteatro del garda studiato. non sono compresi in questo schema l'allogruppo di rio naviglio e il conglomerato di pisenze. la sigla pg si riferisce all'unità postglaciale. stratigraphic framework in the portion of the amphiteatre here studied. allogruppo di rio naviglio and conglomerato di pisenze are not included. pg refers to postglacial unit. a. bini & l. zuccoli glaciali e fluvioglaciali cementati. il limite superiore è graduale ad organi geologici con la formazione di cascina colombera. l'unità copre il conglomerato del castello di muscoline a nw dell'area sinora rilevata. in tutto il territorio rilevato sono stati attribuiti al conglomerato di cà dell'ava tutti i conglomerati in facies glaciale e fluvioglaciale che costituiscono l'anima dei numerosi dossi dell'anfiteatro. in questo settore il conglomerato è fortemente eroso ed è coperto da tutte le unità più recenti. nella zona a nord (tra cà dell'ava e muscoline), si distinguono due fasi formative separate da una superficie di discontinuità (ca1 e ca2) allogruppo di rio naviglio (nav) l'allogruppo è stato istituito per comprendere tutti depositi di facies glaciale e fluvioglaciale, cementati e non cementati affioranti al di sotto delle alloformazioni di monte san pietro e di puegnago, sul lato interno, lungo il rio naviglio. unità di picedo (npi) costituita da depositi glaciali e fluvioglaciali induriti e glaciotettonizzati. affiora solo in due affioramenti presso picedo. il limite inferiore è ignoto, mentre a tetto è limitata da una superficie di erosione sopra la quale si trova l'alloformazione di puegnago. conglomerato del castello di muscoline (cam) ghiaia litificata, grossolanamente stratificata di petrografia omogenea esclusivamente carbonatica. forma il ripiano di muscoline e il rilievo del castello in corrispondenza dei quali affiora in tutte le incisioni vallive. secondo venzo (1957, 1965) questo conglomerato, benchè un po' più grossolano, è analogo a quello che affiora a san bartolomeo di salò e che è di età messiniana. i due conglomerati sono in realtà differenti e di conseguenza non si ritiene valida, allo stato attuale, questa correlazione e l'età attribuita al conglomerato di muscoline. il conglomerato del castello di muscoline è coperto da tutte le unità più recenti, in particolare dal conglomerato di cà dell'ava. a tetto si osserva il passaggio all'alterite sviluppata sul conglomerato. il conglomerato si presenta di colore biancastro e fragile con limite superiore ondulato a tasche. l'alterite è costituita da fini massivi ricchi in argilla (orizzonte bt) di colore 10yr6/6 e limite superiore netto erosivo. il passaggio alle alteriti e le alteriti stesse sono attualmente poco visibili in quanto le alteriti sono state oggetto di intenso sfruttamento per la fabbricazione di laterizi. allogruppo di moniga del bosco (mon) l'allogruppo comprende depositi colluviali polifasici provenienti dalle alloformazioni di monte serina, di monte cervo, di monte forca e dalla formazione di cascina colombera. costituisce parte del ferretto degli autori precedenti. il colore è compreso nella pagina 7.5yr delle tavole munsell. lo spessore può essere notevole, l'unità infatti riempie le valli tra i dossi di conglomerato di cà dell'ava. il limite con le unità sottostanti è una superficie di erosione. formazione di torre (tor) unità litostratigrafica costituita dal conglomerato di calvagese alterato. l'unità è stata denominata da venzo: morenico del mindel i, morena di fondo (1957) e morenico del mindel ii (1965). affiora a nord della località torre nell’impluvio sulla sinistra del fiume chiese, a nord di mocasina. si tratta di ghiaie alterate con livelli di sedimenti fini cementati. a letto l'unità passa gradualmente, con limite ad organi geologici, al conglomerato di calvagese, mentre il limite superiore non è stato osservato perchè coperto, ma è ragionevole supporre che l'unità sia coperta dal conglomerato di ca’ dell’ava che affiora pochi metri più in alto, spostato di circa 50 m. conglomerato di calvagese (cal) e' un'unità litostratigrafica costituita da depositi fluviali cementati. l'unità è stata denominata da venzo: ceppo poligenico del günz-mindel (1957) e anaglaciale mindel (1965). affiora solo in due impluvi sulla sinistra del fiume chiese, nei pressi di calvagese della riviera e a nord di mocasina, e nel vallone della valle. si tratta di ghiaie poligeniche, stratificate verso l’alto con immersione verso w, ben cementate. l'unità poggia sulla formazione di ponte clisi è passa gradualmente verso l'alto, con limite ad organi geologici, alla formazione di torre. formazione di ponte clisi (pc) si tratta di un'unità litostratigrafica costituita da depositi glaciali cementati. l'unità è stata denominata da venzo: morenico a ciottoloni alpini del günz ii (1957) e morenico alpino del günz iii (1965). affiora solo in due impluvi sulla sinistra del fiume chiese, nei pressi di calvagese della riviera e a nord di mocasina. alla base è presente una tillite costituita da till di alloggiamento (fini massivi con clasti carbonatici sparsi, alcuni striati e sagomati a ferro da stiro); segue una tillite costituita da till di ablazione contenente massi, quindi un’alternanza di: limi laminati, sabbie medio-grossolane laminate, ghiaie medie e sabbie e argilla parzialmente cementati. il limite inferiore è sconosciuto, il limite superiore è costituito da una superficie di erosione coperta dal conglomerato di calvagese. conglomerato di pisenze (pis) unità litostratigrafica costituita da depositi fluvioglaciali di ambiente deltizio cementati. affiora sul versante settentrionale della rocca di manerba. conclusioni il rilevamento di dettaglio di parte dell'anfiteatro del garda ha permesso di distinguere e cartografare varie unità allostratigrafiche e litostratigrafiche. i metodi utilizzati in questo rilevamento sono in parte differenti da quelli che sono stati impiegati negli anfiteatri già rilevati (bini 1997b, bini et al., 2001) a dimostrazione del fatto che non esiste una regola generale di rilevamento del quaternario continentale valida per qualunque luogo e qualunque contesto. in ogni nuova situazione che si affronta è necessario rivedere, adattare i criteri di rilevamento e metterne a punto di nuovi specifici per quel contesto. le unità che contengono depositi glaciali differenti sono sinora otto. non essendo stato rilevato l'intero anfiteatro è possibile che questo numero vari in futuro; 341prime note sul rilevamento ... del resto è noto (bini et al., 1992; bini 1997, bini et al., 2001) che le unità definitive nel rilevamento del quaternario vanno decise solo al termine del rilevamento stesso. per tali motivi non c'è da stupirsi, come invece fa minelli (1997), del fatto che venzo abbia cambiato idea dal 1957 al 1965 quando ha terminato il rilievo: il metodo di venzo è ormai superato, ma non i concetti geologici di base, per cui le conclusioni sulle unità e sull'evoluzione di un bacino sedimentario, sia esso giurassico o quaternario, si possono trarre solo al termine del rilevamento dell'intero bacino. e' comunque più probabile che non subiscano variazioni le unità interne, mentre altre unità potrebbero aggiungersi all'esterno. le glaciazioni sinora individuate secondo la definizione di richmond (1986),sono: la glaciazione garda, la glaciazione puegnago, la glaciazione monte san pietro, la glaciazione monte forca, la glaciazione monte cervo, la glaciazione monte serina; la glaciazione cà dell'ava e la glaciazione ponte clisi. riguardo al problema dell'età delle cerchie moreniche si deve evidenziare come non sia possibile una soluzione sino a che tutti i geologi, che si interessano anche solo marginalmente al quaternario, non parleranno la stessa lingua. ringraziamenti il lavoro che abbiamo svolto in questi ultimi tre anni, dal 2000 al 2003, non sarebbe stato possibile senza il contributo fondamentale dei nostri studenti: alpago daniele, amigoni edda, anselmi silvia, arpaia paolo, barilli nicola, barzaghi fiorella, bigoni paolo, bonavera mauro, bonzini maria, brioschi laura, brivio luca, colombini ivan, conti roberto, cuzzilla roberta, dell'arciprete diana, dell'orto stefano, drera rosa, felisari andrea, franciamore valeria, galli giuditta, gardoni barbara, gentile erika, gerosa michela, ghiselli alice, grassi davide, grosso davide, locatelli elena, lunghi riccardo, lupis domenico, mainardi dario, mangialetti morena, marchesi cinzia, massaro costanza, molinari michele, monti matteo, moro daniele, pagnoncelli tecla, panella antonio, pasqualino di marineo maria, pedersoli maria teresa, pitaro saverio, pomati davide, pozzi paolo, raimondi matteo, rech alberto, redaelli chiara, ronchetti maurizio, ruggiero mario, santambrogio daniela, sarti chiara, sarti ilaria, scacciante davide, scazzosi valentino, scola simone, soffritti valeria, sommariva nicola, sozzani marta, tendas antonio, turisini chiara, villa ilaria, villa laura, zambarnieri elisa. bibliografia bini a., bosi c., carraro f. e castiglioni g.b. (1992) cartografia geologica del quaternario continentale in: consiglio nazionale delle ricerche, commissione per la cartografia geologica e geomorfologica: carta geologica d'italia 1:50.000 guida al rilevamento, servizio geologico nazionale quaderni (iii) vol. 1: 67 86 bini a. (1997) problems and methodologies in the study of the quaternary deposits of the southern side of the alps southern alps quaternary geology, igcp 378 meeting, lugano ottobre 1995. geologia insubrica 2 (2): 11 20 bini a. (1997) stratigraphy, chronology and palaeogeography of quaternary deposits of the area between the ticino and olona rivers (italyswitzerland) southern alps quaternary geology, igcp 378 meeting, lugano ottobre 1995. geologia insubrica 2 (2): 21 46 bini a., felber m., pomicino n. e zuccoli l. (2001) geologia del mendrisiotto (canton ticino, svizzera): messiniano, pliocene e quaternario berichte des bundesamt für wasser und geologie / rapporti dell'ufficio federale delle acque e della geologia bwg/ufaeg 1: 459 pp co z z a g l i o a. (1934a) carta geologica delle tre venezie. foglio peschiera mag. acque, venezia co z z a g l i o a. (1934b) carta geologica delle tre venezie. foglio mantova mag. acque, venezia cozzaglio a. (1939) carta geologica d'italia. foglio brescia ufficio geologico roma cozzaglio a. (1933) note illustrative della carta geologica delle tre venezie. fogli peschiera e mantova mag. acque sezione geologica, padova cremaschi m. (1987) paleosol and vetusols in the central po plain (northen italy) a study in quaternary geology and soil developement edizioni unicopli, milano habbe k. a. (1969) die würmzeitliche vergletscherung des gardasee-gebietes freiburger geographische arbeiten 3. minelli r. (1997) i suoli dell'area morenica gardesana settore bresciano ersal p e n c k a. e b r u c k n e r e. (1909) die alpen im eiszeitalter leipzig, bd. 3. richmond g.m. (1962) quaternary stratigraphy of the la sal mountains utah geological survey professional paper, 324: 1-103. richmond g.m. (1986) stratigraphy and chronology of glaciations in yellowstone national park in: sibrava v., bowen d.q. e richmond g.m. (eds.) quaternary glaciations in the northern hemisphere. report igcp n°24, quaternary science reviews 5(1-4): 83 98 venzo s. (1957) rilevamento geologico dell'anfiteatro morenico del garda. parte i: tratto occidentale gardone-desenzano mem. soc. it. sc. nat. e museo civ. st. nat. milano, xii (fasc. ii): 73 140. venzo s. (1961) rilevamento geologico dell'anfiteatro morenico del garda. parte ii: tratto orientale garda-adige e anfiteatro atesino di rivoli veronese mem. soc. it. sc. nat., v. 13, n. 1: 164. milano venzo s. (1965) rilevamento geologico dell'anfiteatro morenico frontale del garda dal chiese all'adige mem. soc. it. sc. nat. e mus. civ. st. nat. milano, xiv (fasc. i): 3 82. 342 ms. ricevuto l’11 maggio 2004 testo definitivo ricevuto il 1° settembre 2004 ms. received: maj 11, 2004 final text received: september 1, 2004 a. bini & l. zuccoli imp.reynard geomorphological sites, public policies and property rights. conceptualization and examples from switzerland emmanuel reynard institute of geography, university of lausanne, bfsh 2 – dorigny, ch – 1015 lausanne emmanuel.reynard@unil.ch abstract: e. reynard, geomorphological sites, public policies and property rights. conceptualization and examples from switzerland. (it issn 0394-3356, 2005). the paper analyses the importance of institutional rules for protecting and managing geomorphological sites. a framework, called institutional resource regime (irr), is proposed. it considers a natural resource, and more specifically geomorphological sites, in a systemic manner, and combines the analysis of the property rights concerning the resource and the public policies regulating its exploitation and protection. two examples are presented in order to illustrate the analytical possibilities offered by the irr concept and the necessity to develop specific and adequate institutional tools in order to guarantee efficient protection of geomorphological sites. riassunto: e. reynard, siti geomorfologici, politiche pubbliche e diritti di proprietà. analisi ed esempi in svizzera. (it issn 03943356, 2005). l’articolo mette in evidenza l’importanza di sviluppare regole istituzionali che permettano di proteggere e gestire i siti geomorfologici in modo adeguato. viene proposto un quadro analitico chiamato regime istituzionale di risorse (rir), che considera una risorsa naturale, e più particolarmente i siti geomorfologici, in un modo sistemico e combina l’analisi dei diritti di proprietà concernenti la risorsa e delle politiche pubbliche che regolano tale risorsa. due esempi illustrano le possibilità analitiche offerte dal concetto rir e dimostrano la necessità di sviluppare strumenti istituzionali adeguati per garantire una protezione efficace dei siti geomorfologici. keywords: geomorphological sites, protection, public policies, property rights, institutional resource regime. parole chiave: beni geomorfologici, protezione, politiche pubbliche, diritti di proprietà. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 323-332 1. introduction geomorphological sites (or geomorphological assets) are defined as geomorphological landforms (and processes) that have acquired a scientific, cultural/historical, aesthetic and/or social/economic value due to human perception or exploitation (panizza & piacente, 1993; quaranta, 1993). more precisely, they have a particular importance for reconstructing, explaining and recording the history of earth, its climate and all the life it supports (grandgirard, 1997). they can be single geomorphological objects (e.g. waterfall, inselberg, erratic block, dune, etc.) or larger landscapes (e.g. glacier forefields, marine coasts, alluvial fans, etc.). the value of a site can be of four types (panizza & piacente, 1993, 2003; quaranta, 1993): scientific (e.g. a moraine representative of a glacier extension, an artificial trench allowing observation of a transition in a sediment succession), cultural/historical (e.g. a mountain that has religious or mystic value or a landform/landscape that is a support for cultural/historical activities or infrastructures), aesthetic (e.g. some amazing mountainous, coastal or desert landscapes), and social/economic (e.g. aesthetic landscapes as tourist destinations). as indicated by cavallin et al. (1994), geomorphological sites may be modified, damaged, and even destroyed, by direct or indirect impacts of human activity. direct impacts are defined as active modifications of a geomorphological site by human activity (e.g. destruction of a morainic crest by road construction, modification of the aesthetic value of a coastal environment by the building of a tourist settlement), whereas indirect impacts do not have direct contact with the geomorphological site but highly affect it (e.g. sedimentation changes in an alluvial fan by gravel extraction upstream, reduction of the view of a geomorphological asset by the construction of buildings). due to their vulnerability, most geomorphological sites need to be protected against direct and indirect human impacts. the first step in a protection process is to assess the value of geomorphological sites (panizza & piacente, 1993, 2003; panizza et al., 1995a; grandgirard 1999a). numerous more or less quantitative methods have been proposed for evaluating the quality of geomorphological sites (quaranta, 1993; panizza et al., 1995b; rivas et al., 1997; boyer et al., 1998; grandgirard, 1999a; coratza & giusti, 2003), especially in the context of environmental impact assessment (eia) procedures. proposals have also been made for conducting inventories of geomorphological sites at a regional scale (grandgirard, 1999b). the objective of this paper is to discuss the second step of a procedure for the protection of geomorphological sites, that is, the implementation of rules (restrictions of use, bans, access regulation, management of the material extraction, etc.), aiming to regulate the “exploitation” of geomorphological sites. the third 324 e. reynard step should be to assess the effects of the regulation on the quality of the sites and on the sustainability of their management. i will use the institutional resource regime (irr) concept, a framework that was developed for analysing the quality of natural resource management from an institutional point of view (kissling-näf & varone, 2000; knoepfel et al., 2001), and that we consider useful for developing strategies for the protection of geomorphological sites (reynard, 2002). we will first describe the relationships between geomorphological sites and natural resources. then, the irr concept will be presented and applied to the geomorphological sites analysis. two swiss examples demonstrating the interest of the irr concept in the area of geomorphological site protection, will finally be presented. 2. geomorphological sites as natural resources as geomorphological sites are in contact with human activities, and because they are exploited, even from an immaterial point of view (e.g. the observation of a landscape dominated by geomorphological landforms), they may be considered as natural resources. we define a natural resource as the part of the natural environment used by humans for satisfying their needs (siebert, 1983). in this anthropologically centered definition, natural resources are culturally defined (grima & berkes, 1989); nature becomes a natural resource only when humans give it a value. in this sense, as an example, gas and oil were not natural resources for the north american indians of 1800 (grima & berkes, 1989). in every process of resource exploitation, the stock of the resource and the yield are distinguished (ostrom, 1990). the stock is the amount of resource that is naturally renewed in the case of a renewable natural resources (e.g. underground water that is renewed every year by the hydrological cycle) or that is not renewed in the case of non-renewable resources (e.g. oil, gas). the yield is the product of the stock. in the case of water, for example, the stock is the quantity of water involved in the natural water cycle of a watershed. the yield is the amount of water that is available to humans for satisfying their needs for consumption, irrigation, industrial production, etc. when the total amount of water uses is higher than the yield, there is overexploitation. from an economic point of view, natural resources are considered in order to create goods and services for society (grima & berkes, 1989). goods and services are produced either by the stock or the yield (fig. 1). in the case of forests, the wood is a good produced by the yield in a situation of sustainable exploitation, and by the stock in a situation of overexploitation. the space for recreation and the protection of infrastructures against natural hazards (avalanches, debris flows) are services produced by the stock and the yield. the production of biodiversity is a good and a service produced by the stock and the yield. the goods and services are used by humans in three different ways (knoepfel et al., 2001): direct uses (e.g. direct consumption, input in the industrial production), indirect uses (e.g. air and water as receptacle for the absorption of waste), and immaterial uses (e.g. aesthetic or cultural value of a landscape). from a geomorphological point of view, rivas et al. (1997) distinguish consumable and non-consumable geomorphological resources: consumable resources are those used for construction and other material extraction, whereas non-consumable resources include all the geomorphological elements that do not imply the direct extraction and consumption of material. the authors also include in that category landforms as part of the landscape, the sites of geomorphological interest from a scientific, pedagogic and recreational point of view, and geomorphological units as support for other elements of the environment, especially ecosystems. they add that geomorphological processes may represent natural hazards and contribute to environmental change (see also cavallin et al., 1994). extraction may be considered to produce goods (fig. 2) coming either from the stock (e.g. extraction of gravels from alluvial terraces) or from the yield (e.g. extraction of gravels directly from a river bed or active deltaic fan). we can also consider that geomorphological (or geological) processes may be, under certain conditions, a type of natural resource (e.g. fluvial flow used for energy production, volcanic eruption and geysers as tourist resource for regions like hawai or iceland, geomorphological features as support for specific human activities like canyoning, etc.). on the other hand, not all the geomorphological resources are to be considered as geomorphological sites. finally, we can consider that geomorphological assets are part of the landscape resource of a region. as well as for other natural resources, there is increasing competition for geomorphological sites between various users or user groups that have quite different, and sometimes contradictory, interests and perceptions of the value of the resource. such rivalries may be mitigated by defining regulations and institutions, whose objectives should be the co-ordination between rival uses in order to avoid conflicts, the planfig. 1 stock and yield in relation with goods and services produced by a renewable natural resource. ammontare (stock) e prodotti rinnovabili (yield) in relazione ai beni e servizi prodotti da una risorsa naturale rinnovabile. ning of long-term resource management and the preservation of the resource stock in order to be able to satisfy the needs of future generations (fig. 3). i propose to use the institutional resource regime (irr) framework developed by kissling-näf & varone (2000) and knoepfel et al. (2001) as the analysis method. 325geomorphological sites, public policies ... 3. institutional resource regime (irr) the irr concept considers all the uses of a natural resource as a whole. a renewable natural resource is generally exploited by more than one type of users. forests, for example, are used for various kinds of wood exploitation (e.g. fire, construction), other material exploitation (e.g. mushrooms), protection (e.g. against rockslides and avalanches), leisure (e.g. walking) and biodiversity conservation. management of such highly heterogeneous resource use systems needs efficient institutional regulations; sustainability of resource management is supposed to depend on the institutional framework. the irr concept allows the analysis of all the components of these institutional conditions. an institutional resource regime (fig. 4) is defined as the combination of the property regime and public policies that regulate the natural resource management (knoepfel et al., 2001). the property regime is analysed through three types of property rights (formal property titles (ownership), disposition rights and use rights) and two categories of public policies are considered: exploitation and protection policies. four types of ownership have been defined (e.g. ostrom, 1990; bromley, 1991; devlin & grafton, 1998): private property, state property, common property, and no property (tab. 1). two complementary dimensions are also considered: the extent and the coherence. the extent describes the number of goods and services explicitly regulated by the irr. the coherence concerns the degree of co-ordination of the actors’ network, mainly the co-ordination between the owners and the actors involved in the implementation of public policies. the irr are then classified into four regime types: no regime, simple regime, complex regime and integrated regime, by combining the extent and the coherence (kissling-näf & varone, 2000 and tab. 2). we speak of a "no regime situation", in cases where neither ownership, disposition, use rights, nor public policies exist. chances are, in this instance, that a resource has not yet been discovered. this was the case for biodiversity until recently; it is certainly the case for geodiversity, a resource that has not been defined precisely until now. if the use rights are formulated either directly and/or at least indirectly through an initial policy design (e.g. bans, limitation of access), this can be referred to as a “simple regime”. we suspect that this kind of simple regime emerges when the central actors observe rivalry and scarcity in connection with the predominantly fig. 2 examples of goods and services produced by geomorphological processes and landforms. esempi di beni e servizi prodotti da processi e forme geomorfologiche. fig. 3 conceptual model describing the relationships between institutions, actors and natural resources (from kissling-näf & varone, 2000, modified). modello concettuale che mette in evidenza le relazioni fra istituzioni, attori e risorsa naturale (da kissling-näf & varone, 2000, modificato). fig. 4 components of an institutional resource regime. componenti di un regime istituzionale di risorse. 326 homogenous use of one or several goods or services provided by a given resource and this becomes a collective problem because of the risk of overuse. in most countries, geosites and landscapes in general could be considered to be in this situation: there is a problem of management, but few regulations have been produced until now. in a “complex situation”, we can already observe differentiation on the basis of the specific uses of the resource (goods and services provided by the resource) and the combining of the formal ownership, disposition and use rights with more detailed public policies. the heterogeneous demands and the sum of the diverse use rights could lead to a crisis and possibly even the collapse of the complex regime. examples of such competing and excessive uses can be found in the area of land (e.g. agriculture, construction zones, roads and railways, etc.), water (e.g. fishing, energy, agriculture, drinking water, etc.) and forest (e.g. biodiversity, recreation, timber, etc.). an institutional regime which can take into account the heterogeneous demands and regulate the totality of the uses in order to maintain the capacity of the renewability of the resource is considered as an “integrated regime”. we assume that such a regime may promote sustainability, that is to guarantee the transparent satisfaction of the heterogeneous use requirements and to conserve the resource stock. the analysis of the institutional regime of a resource is carried out in five successive steps (reynard, 2002). first, the resource perimeter is defined and a compilation of the various goods and services provided by the resource is made in order to represent the main current rivalries, the historical evolution of the relationships between goods and services, and the principal transformations of the resource stock and yield. this part of the analysis concerns essentially the resource and its characteristics. then, the property regime (formal ownership, disposition rights and use rights) and the public policies related to the resource exploitation and protection are successively analysed. the first three steps are then combined to characterise the resource regime. it is assumed that simple or integrated regimes are more sustainable than complex regimes. the last step is dedicated to the improvement (if necessary) of the resource regime in order to improve sustainability. thus, the systemic irr analysis is assumed to allow a rational selection of management instruments. 4. geomorphological sites and institutional resource regimes if we consider the management of geomorphological sites in a systemic manner, the irr appears to be an adequate tool for analysing the various uses of geomorphological sites by humans and for improving management mechanisms. in this section, we successively analyse what the goods and services provided by a geomorphological site are, and in which way property rights and public policies are important tools for managing geomorphological sites. the principal goods and services produced by geomorphological sites are presented in table 3. thirteen types of uses are proposed, following the typology proposed by bisang et al. (2000) for the resource “landscape”. these uses are grouped in three large categories of geomorphological sites: a) natural heritage (support for life and earth science heritage), b) cultural heritage (cultural, symbolic, religious, pedagogic value), and c) objects for economic uses (support and spaces for tourist and other economic uses). in most cases, a geomorphological site combines several values coming from the three categories. for example, the famous uluru (ayers rock) in central australia (fig. 5), combines the following goods and services. as it is a characteristic example of an inselberg, it has a geomorphological value (twidale, 1978). e. reynard tab. 1 classification of property rights (from knoepfel et al., 2001, modified). classificazione dei diritti di proprietà (da knoepfel et al., 2001, modificato). private state common no property property property property open access owner of the people, state: local associations, nobody property title private municipalities, corporations societies region, state, etc. exclusion yes yes yes no example soil, forests national parks alpine meadows air, landscape tab. 2 classification of resource institutional regimes (from kissling-näf & varone, 2000). classificazione dei regimi istituzionali di risorse (da kissling-näf & varone, 2000). institutional resource regime (irr) coherence of the actors within the public policies and the property rights system high low range of regulated goods and high integrated regime complex regime services (derived from the low simple regime no regimeresource) fig. 5 uluru (ayers rock), an australian geomorphological site with several rival uses. uluru (ayers rock), un geomorfosito australiano con parecchi usi possibili, tra loro contrastanti. 327 the vertically stratified sandstones testify the existence of an ancient delta that was removed by tectonic movements (earth history value). the taffonis that can be shown at its surface give evidence of climate change (climate history reconstruction). the rock and its surroundings provide habitat for specific fauna and flora (ecological value). it also has an aesthetic, and in this case we could also add a “photogenic”, value as impressive landscape, because of its varying appearance with the changes in light (sunrise and sunshine). uluru also has a religious and symbolic value for the aborigines; it was also used as one of the symbols for the political actions of the aborigines for recovering the sovereignty over their land. because of its high earth science value, it also has pedagogic value for students, scientists and tourists. this impressive and unique landscape is the basis for very fruitful tourist exploitation, with rapid development of derived offers (camping, hostels, sunshine and sunrise observation places, guided visits, cultural aborigine centre, etc.) around the original offer (landscape) (for an analysis of the distinction between original and derived tourist offer in the domain of geomorphology, see pralong & reynard, 2005) the area has provoked major impacts either on the natural values of the rock and its surroundings (ecological and geomorphological processes) or on the aborigine culture (e.g. climbing on the rock, which is “forbidden” by the aborigine religion). these rivalries are mitigated either by property rights instruments (e.g. limited access to some religious and ecologically fragile sites), or by public policies (e.g. 1990s amendments of the australian legislation that gave aborigines new sovereignty over their land, creation of a national park). new instruments (e.g. forbidden access to the top of the rock) would certainly improve the co-ordination between the tourist industry, cultural, ecological and geomorphological protection in the area. in order to develop sustainable management of geomorphological sites, public policies ... tab. 3 goods and services provided by geomorphological sites (from reynard, 2002, modified). beni e servizi prodotti da siti geomorfologici (da reynard, 2002, modificato). category of use type of use principal users examples a) natural heritage life support all living beings volcanoes (that support a large range (humans, animals, plants) of human settlements) biodiversity heritage humanity, future generations, deltas or alluvial plains (that are often scientists, tourists environments with high vegetal and animal biodiversity) earth history heritage humanity, future generations, moraines or erratic blocks (that testify scientists, tourists former glacial extents) b) cultural heritage support for cultural humanity, future generations, isolated mounts, locks (that are often heritage scientists, tourists occupied by castles and fortresses) aesthetic heritage painters, photographs, impressive landscapes tourists space for cultural local population large natural regions (e.g. the alps, and religious islands), religious monuments identification (e.g. uluru for australian aborigines) space for political local population, saharan landscapes for the tuaregs identification politicians, state pedagogic sites schools, environmental cross-sections in sediment deposits, organisations, scientists sites where active processes are visible c) economic landscape with tourists, tourist industry, impressive landscapes (e.g. ayers rock, exploitation tourist/leisure local population grand canyon, matterhorn) valorisation framework for tourists, tourist industry, coasts (for bathing), mountains tourist/leisure local population (for hiking or skiing) activities support for specific tourists, tourist industry, cliffs (for climbing), reefs (for diving), rivers tourist/leisure local population (for canyoning) activities other economic industry, agriculture glacial locks (that are often sites for dam uses building), specific agriculture in sinkholes in the french causses, gravel extraction in braided rivers support for transport state, industry valleys (used for road or rail tracks construction), mounts (for building antennae) 328 geomorphological sites, the three dimensions (natural, cultural/social, and economic needs) should be taken into account. in this specific case, all three categories of uses and their respective relationships have been considered. this example also shows that rivalries and potential conflicts may be mitigated by creating and organising property rights and/or by developing public policies. table 4 summarises the various possibilities of regulating the sites’ management by using property instruments. the management, and especially the protection, of geomorphological sites largely depends on the public policies regulating the environmental protection and the resource exploitation of a country. restrictive policies concerning the resource exploitation (hydropower production, mining, territorial planning, etc.) are generally beneficial for the protection of geomorphological sites. moreover, explicit mention of the protection of geomorphological sites in the environmental policies is better than more general environmental protection policies. accurate analysis of public policies is therefore essential for guaranteeing effective protection of geomorphological sites and co-ordination with other human activities. in contrast with other european countries, like great britain, that has adopted a specific law for the protection of geological heritage, switzerland does not have a particular legislation for the protection of geological or geomorphological sites (jordan, 1999). until the adoption of the nature protection act in 1966, the geological heritage could only be protected by the private right (swiss civil code of 1912, article 724). in contrast with biotopes, that are explicitly protected, the nature protection act has no specific article aiming at the protection of geosites, even if the protection of the geological particularities is mentioned as one of the objectives of the law. the nature protection act introduced a new instrument: the inventory, which is a list of objects worthy of conservation. since, several inventories have been established by the federal government, some of them with partial reference to geosite conservation. that is the case of the natural and cultural landscapes inventory (1977), the moor landscapes inventory (1996), or the proglacial margins and alpine alluvial zones inventory (2001). none of these inventories are specifically dedicated to a geosite listing and the degree of protection varies greatly from one inventory to another. an unofficial geosite inventory has been produced by a group of experts under the auspice of the swiss academy of science (sas, 1999): the inventory, which lists 401 sites, has no legal incentive for the political authorities. a second group of experts has since produced a report on the opportunity of an official geosite inventory to be carried out by the federal e. reynard tab. 4 categories and swiss examples of property rights relating to geomorphological sites. categorie ed esempi svizzeri di diritti di proprietà concernenti siti geomorfologici. private state common non property property property property (open access) formal property geomorphological geomorphological geomorphological geomorphological rights site bought by an site managed by a site localised in a site localised in (ownership) environmental national park commonly owned alpine elevated non organisation administration space and managed by productive terrains the communal association (normally owned by example: swiss rock glaciers and the state but erratic blocks bought other landforms tortin morainic system considered or received as a gift included in the (valais, switzerland), as res nullius) by scientific swiss national type-locality for the egesen associations park (chaix, 1943) glacial stage in the western periglacial and (19th century) alps, property of a local glacial landforms (bachmann, 1999) corporation (kuonen, 1992) of the tourist area of verbier (lambiel & reynard, 2003) disposition servitude to an state decree for ? -rights environmental classifying a organisation geosite servitude to the classification of sites environmental ngo of interest by the pronatura for 100 years cantons or the on the alpine area of federal state la pierreuse (gentizon, 2004) use rights fee for visiting the restrictions for ? -caves of the hölloch visiting the swiss system national park (canton schwyz) government (gerber & gsteiger, 2000); such an inventory is not a political priority for the moment. at a lower political level, on the other hand, several cantons and some communes have carried out geosite inventories (jordan, 1999). the canton governments also have the possibility of protecting sites of interest by decree. another way of protecting geosites in switzerland refers to the territorial planning act (1979), whose article 17 allows the creation of protection zones for sites with high landscape and/or natural value (stürm, 1994; strasser et al., 1995; jordan, 1999). the recent modification of the forest act (1991) allows the long-term protection of sites discovered by engineering works (strasser et al., 1995). until now, reforestation after the end of the works was obligatory, a situation that could be in opposition with geosite conservation policy. some sites are also integrated in international lists of valuable sites, like the aletsch-jungfrau region in the unesco world heritage list or the entlebuch region in the unesco biosphere reserve list. some regions, like the glarnerland-sarganserland area, are also hoping to obtain the “geopark” unesco label. this rapid overview shows how the protection of geomorphological sites by public policies may be complex and highly dependent on the sensitivity of political authorities to the protection of the geological heritage. this latter is perceived more as pure support for the development of economic activities than a dynamic component of the environment to be protected and managed with accuracy, as well as the biotic environment. the following section is dedicated to the presentation of two cases. the first case, concerning the protection of erratic blocks in the central plateau of switzerland, illustrates the protection through property rights instruments; the second example is about the karstic area of tsanfleuron (valais) and shows the difficulty of protecting the geomorphological heritage in the absence of a specific protection policy. 5. two cases in switzerland the first example refers to the protection of erratic blocks in the central plateau of switzerland (favre, 1989; aubert, 1989; bachmann, 1999). these blocks were one of the indices that allowed the development of the glacial theory by scientists like ignaz venetz, jean de charpentier and louis agassiz at the beginning of the 19th century (schaer, 2000). they therefore have either a paleoclimatic (as landforms allowing the reconstruction of former extensions of alpine glaciers) or a geohistorical value (as objects at the origin of the development of a scientific theory). during the 19th century, they were intensively exploited as construction material, because of their specific petrography (mainly granites). that exploitation represented an interesting financial income for their owners, who were public bodies (communes) as well as private proprietors. therefore, there was clearly a rivalry between two competitive uses: the exploitation as construction material and the protection as heritage of the climate history and testimony of the geoscience history. in absence of a specific public policy for the nature protection, the only way for protecting the blocks was to buy or acquire them as gifts from communes or private owners. that is for example the case of several blocks situated in the canton of vaud (aubert, 1989) or neuchâtel, that were acquired by the local sections of the helvetic society of natural sciences (now swiss academy of science) or by the state. one of these blocks is the pierre des marmettes (fig. 6), a 1824 cubic metres block, situated on a last glacial moraine of the rhone glacier, near monthey in the canton of valais. in 1905, the block was to be exploited for granite extraction. because of its height and its high value for geological sciences, the project of exploitation provoked a large reaction both among the public and in scientific circles (schardt, 1908). in 1908, the helvetic society of natural sciences were able to acquire it for 31’500 swiss francs, subscribed by the confederation, the canton of valais, various societies and the public (aubert, 1989). after several decades, in 1983, it was included in the natural and cultural landscapes inventory. in 1999, the block was also proposed for the unofficial geosite inventory of the swiss academy of sciences (sas, 1999). 329geomorphological sites, public policies ... fig. 6 the pierre des marmettes (monthey, switzerland): an erratic block property of the swiss academy of sciences since 1908 (photography: j.p. pralong). la pierre des marmettes (monthey, svizzera): un blocco erratico proprietà dell’accademia svizzera delle scienze naturali sin dal 1908 (fotografia: j.p. pralong). the second example concerns the karstic area of tsanfleuron in the diablerets range (western switzerland). the zone has a high geomorphological value because of the presence of specific landforms and processes typical of a karstic plateau recently deglaciated, and the high sensitivity of the tsanfleuron glacier to climate variations (reynard et al., 2003). since the 1960s, the area has developed either intensive winter tourism (skiing) or more extensive summer tourism (hiking). because of the absence of a specific geosite protection policy, geomorphology was highly modified by road and infrastructure building. the main impact was the construction of a road aiming to mitigate the sharp topography of the superficial karst and to facilitate the preparation of ski runs (fig. 7). the material used for the road construction was extracted from a little ice age morainic crest. the works were performed without any authorisation and testify the absence of geomorphological sensitivity of the local authorities (reynard et al., 2003). because of opposition, the works were finally stopped by the cantonal administration and an environmental impact assessment (eia) was performed a posteriori. the eia recommended the dismantling of the road and the recovering of the morainic crest, which was carried out in autumn 2002. the landscape value of the moraine is therefore reconstructed, even if the sedimentological characters of the deposits are not the original ones. this example shows the difficulties associated with protecting the scientific and geohistoric value of gemorphological sites in a situation where there is an absence of specific geosite conservation legislation. without other more biological values (e.g. presence of biotopes, fragile ecosystems, etc.), geomorphological sites present a high vulnerability, principally because of the low sensitivity of the political authorities and the public in general for the geoscientific value and for the “beauty” of mineral landscapes. 6. conclusions the aim of this paper was to point out the importance of crafting adequate institutional rules in order to protect and manage geomorphological sites. once a gemorphological site has been assessed and its value has been shown, measures have to be taken in order to protect the site against negative human impacts. this protection is always developed within a specific institutional framework, which combines property rights as well as public policy aspects. the institutional resource regime (irr) concept allows the management of natural resources to be analysed in a systemic way. the analysed resource is considered to produce goods and services that are exploited by the society; when the uses are numerous and heterogeneous, situations of rivalry between different groups of actors are not uncommon, and institutional rules have to be developed in order to avoid conflicts. rules are developed following two different (but often combined) paths: the public policy and the property right paths. as geomorphological sites protection is poorly developed in most countries and vulnerability of these sites is principally due to the fact that they often combine several conflicting values, the irr concept seems to be an adequate tool for analysing firstly the various rival uses of geomorphological sites, and then secondly, the possible ways of protecting the sites and co-ordinating their uses. thirteen generic types of geomorphological sites uses have been shown and classified in three main categories: natural heritage, cultural heritage, and basis for economic exploitation. the example of uluru (australia) has shown how these types of heterogeneous uses often combine on a particular site and necessitate the adoption of institutional rules for avoiding conflicts. one possible way is to create specific property and use rights, in order to restrict access, for example. the other way is to develop public protection policies that allow the legal protection of sites of interest. the presentation of the development of public policy instruments in switzerland has shown that a specific protection of geosites is not common, mainly because of the absence of political sensitivity for mineral environments, which are considered much more as a support for economic development, than objects and areas with high specific natural value. the example of protection of erratic blocks in switzerland demonstrates how property rights tools may be of high interest for the geomorphological sites protection, for example the purchase of objects or areas by scientific or nature protection associations. on the other hand, the case of tsanfleuron has shown the difficulties of protecting highly valuable sites in the absence of specific policy instruments. the irr approach has not yet been applied systematically at a local or a regional level. the method should now be used for example in a region where a geomorphological sites inventory has been performed, in order to analyse the different uses of the sites of interest, to evaluate their vulnerability and to show the degree of institutional protection and the possible ways of improving it. acknowledgements this research was partly supported by the swiss national science foundation (project: comparative analysis of the formation and outcomes of resource regimes in switzerland, nr. 1214-055890.98.1, codirected by p. knoepfel, i. kissling-näf and f. varone). i strongly acknowledge my colleagues of that project and first of all s. nahrath for his useful comments, as well as the helpful criticisms of f. zarlenga and m. marchetti. 330 e. reynard fig. 7an illegal road built on the karst of tsanfleuron (valais, switzerland) by extracting gravels from a little ice age morainic crest. the road is now dismantled and the moraine recovered 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(1978) on the origin of ayers rock, central australia zeitschr. für geomorphologie, suppl bd, 31, pp. 177-206. 332 e. reynard imp. fusco-riccilucchi ssttoorriiaa ppaalleeoovveeggeettaazziioonnaallee ttaarrddiiggllaacciiaallee--oolloocceenniiccaa nneellll’’aarreeaa ddeell mmaarr ddii mmaarrmmaarraa oorriieennttaallee ffaabbiioo ffuussccoo11 && mmaarriiaannnnaa rriiccccii lluucccchhii11 1dipartimento di scienze della terra e geologico-ambientali, università di bologna, v. zamboni 67, 40127 bologna. (e-mail: fusco@geomin.unibo.it, marianna@geomin.unibo.it) abstract: fusco f. & ricci lucchi m., lateglacial to holocene palaeovegetation changes in eastern marmara sea area (it issn 0394 – 3356, 2004). the history of the vegetation throughout the lateglacial and the holocene is outlined by means of pollen analysis carried out on a core from the eastern marmara sea. six pollen assemblage zones, indicating peculiar vegetation features, have been distinguished and interpreted as the vegetation response to climatic changes. during lateglacial interstadial and younger dryas (corresponding to the lower three zones), only herbaceous and shrubby communities, dominated by artemisia, developed under cold and dry climate conditions. a slight forest expansion characterizes the lower pollen assemblage zone representing the lateglacial interstadial. forest development characterizes the upper three pollen zones and is indicated by both the expansion of arboreal pollen taxa (ap) and increase of pollen concentration. this change is radiocarbon dated to 10,650±40 bp, and is interpreted as the vegetation response to the onset of interglacial climate conditions at the beginning of the holocene. particularly, the first forest phase is characterized by the marked expansion of a mixed deciduous oak forest, which is replaced by a mixed pine-oak forest. the increase of pinus marks the beginning of the mediterranean climate phase. cultivated arboreal taxa (i.e., juglans, castanea, olea and vitis) spread during the upper pollen zone due to human activities. riassunto: fusco f. & ricci lucchi m., storia paleovegetazionale tardiglaciale-olocenica nell’area del mar di marmara orientale. (it issn 0394 – 3356, 2004). viene ricostruita la storia della vegetazione nel tardiglaciale e nell’olocene attraverso l’analisi pollinica di un sondaggio eseguito nel mar di marmara orientale. sono state riconosciute sei zone polliniche corrispondenti a sei differenti fasi vegetazionali, ognuna con proprie caratteristiche di fisionomia e composizione come risposta a peculiari condizioni climatiche. le prime tre comprendono parte dell’oscillazione interstadiale tardiglaciale e il dryas recente e sono caratterizzate da formazioni erbaceo-arbustive dominate da artemisia indicanti un clima generalmente freddo e arido. successivamente si osserva un mutamento molto marcato nella composizione e nella struttura della vegetazione con lo sviluppo di foreste in seguito all’instaurarsi di condizioni climatiche interglaciali. questo cambiamento è datato con un’analisi al radiocarbonio a 10.650±40 anni fa. all’interno dell’olocene si distinguono tre fasi forestali dominate, dapprima, solo da latifoglie decidue (in particolare quercus) e, poi, in associazione con pinus. l’espansione dei pini testimonia un cambiamento nella distribuzione annuale delle precipitazioni in senso mediterraneo. l’ultima fase forestale è caratterizzata dalla diffusione del castagno, dell’olivo, del noce e della vite dovuta presumibilmente all’attività dell’uomo. keywords: palynology, vegetation, lateglacial, holocene, marmara sea parole chiave: palinologia, vegetazione, tardiglaciale, olocene, mar di marmara. il quaternario italian journal of quaternary sciences 1177(1), 2004, 55-61 11.. iinnttrroodduuzziioonnee la ricostruzione della storia vegetazionale del tardo quaternario si basa principalmente sulle analisi palinologiche. in particolare, lo studio del polline fossile in sedimenti marini offre un quadro molto utile perché rispecchia le caratteristiche della vegetazione nelle regioni circostanti il mare, soprattutto dove scarseggiano lunghe e adeguate serie polliniche continentali come l’area adiacente il mar di marmara. lo scopo di questo lavoro è quello di studiare nel dettaglio la storia tardoquaternaria della vegetazione in un’area dalle caratteristiche climatiche peculiari. il mar di marmara, infatti, un piccolo bacino semichiuso nel mediterraneo orientale, si trova interposto tra la fascia delle steppe aride a sud-est e quella delle foreste temperate a nord-ovest, risentendo della loro reciproca vicinanza in relazione alle diverse modificazioni climatiche. esistono pochi studi palinologici di dettaglio in questa zona. koreneva (1971) ha studiato una carota non datata nel mar di marmara occidentale mentre, in un lavoro più recente (mudie et al., 2002), sono state analizzate cinque carote del mar di marmara di età compresa tra 33.500 e 1990 anni fa e una carota del mar nero di età olocenica, mediante le quali viene ricostruita la storia vegetazionale del corridoio mar nero-mar egeo dal pleniglaciale al presente. nel presente lavoro sono riportati i risultati di uno studio palinologico eseguito su una carota prelevata all’imbocco del golfo di i̇zmit a una profondità di -152,6 m, durante una crociera oceanografica organizzata dall’istituto di scienze marine del cnr di bologna. sulla stessa carota sono stati effettuati studi micropaleontologici (foraminiferi e ostracodi), sedimentologici e malacologici i cui risultati sono oggetto di un articolo in preparazione. su frammenti conchigliari rinvenuti all’interno di un intervallo sabbioso alla profondità di 262 cm è stata eseguita una datazione al 14c mediante spettrometria di massa con acceleratore (ams) che ha restituito l’età non calibrata di 10.650±40 anni (c. mchugh, 2002, com. pers.). 56 f. fusco & m. ricci lucchi 22.. llaa vveeggeettaazziioonnee ee iill cclliimmaa aattttuuaallii nel settore orientale del mar di marmara si osservano rilievi che vanno da circa 700 m slm fino a 1600 m slm. il clima attuale è di tipo mediterraneo ma varia in relazione alla distribuzione dei rilievi geografici, passando da zone costiere relativamente umide a zone più interne semiaride. la vegetazione può essere suddivisa in due tipi principali distribuiti per fasce altitudinali (zohary, 1973; roberts & wright, 1993): i) una foresta costiera eu-mediterranea che si spinge fino alla fascia collinare, composta prevalentemente da quercus ilex, q. coccifera, pinus halepensis, p. brutia, olea oleaster var. europea, pistacia lentiscus, con sottobosco ricco di elementi erbacei; le precipitazioni, prevalentemente invernali, variano da circa 300 mm/a a circa 1000 mm/a e la stagione estiva risulta secca; ii) una foresta decidua mesofila a carattere eusinico, in cui gli alberi dominanti sono i faggi, le querce decidue e i pini. le precipitazioni sono distribuite regolarmente nel corso dell’anno con una media superiore ai 600 mm/a. più a est, verso la turchia centrale, si assiste a una graduale transizione verso le steppe aride anatoliche, cioè una vegetazione quasi priva di alberi dominata da artemisia e piante erbacee come asteraceae, poaceae e chenopodiaceae, con le precipitazioni concentrate soprattutto in inverno e mai superiori a 300 mm/a. la zona di transizione verso queste steppe è occupata da una forestasteppa con alberi e arbusti sparsi e precipitazioni comprese tra 300-600 mm/a, concentrate soprattutto d’inverno. 33.. mmaatteerriiaallii ee mmeettooddii la litologia della carota im-5 consiste di peliti grigiastre, a tratti intervallate da livelli millimetrici più sabbiosi, e interrotte nella porzione inferiore da un livello centrimetrico di sabbie conchigliari. al di sotto di questo livello, le peliti sono organiche e laminate, con alcuni livelli conchigliari, mentre quelle sovrastanti appaiono massive e più povere in sostanza organica. sono stati analizzati 39 campioni, trattati seguendo il metodo di laboratorio classico (cf. faegri & iversen, 1989; moore et al., 1991), che consiste in attacchi con hcl 20%, hf 40%, e koh 10%. per la stima delle concentrazioni polliniche è stato utilizzato il metodo di stockmarr (1971) che prevede l’aggiunta di una pasticca con un numero noto di spore di lycopodium sp. all’inizio del trattamento in ogni campione. vengono qui presentati il diagramma pollinico percentuale di dettaglio (fig. 2), il diagramma per gruppi di taxa ad affinità ecologiche e climatiche (fig. 3), il diagramma pollinico sintetico per alberi-pinus-arbusti-erbacee-igro/idrofite assieme a quello delle concentrazioni totali (fig. 4). 44.. ddiiaaggrraammmmii ppoolllliinniiccii i risultati delle analisi palinologiche hanno permesso di definire 6 zone polliniche numerate dal basso verso l’alto dalla im5-1 alla im5-6 (fig. 2 e fig. 3). zona im5-1. la zona è caratterizzata dalla dominanza di piante non-arboree (nap) e da concentrazioni polliniche basse (intorno ai 6000 granuli/g in media). tra gli alberi, si nota un’espansione delle latifoglie (soprattutto di quercus che raggiunge il 30%) e contemporaneamente una riduzione di pinus. zona im5-2. la zona presenta una marcata riduzione delle latifoglie arboree ed è carattizzata dalla dominanza di artemisia (che qui raggiunge percentuali del 50%) accompagnata da un’espansione di pinus e juniperus. zona im5-3. la zona si differenzia dalle precedenti per il calo di artemisia, la marcata espansione delle poaceae e il picco del t. sparganium. tra gli alberi, si osserva un fig. 1 ubicazione del sondaggio im-5. location of the core im-5. 57storia paleovegetazionale tardiglaciale-olocenica ... f ig . 2 d ia g ra m m a p o lli n ic o p e rc e n tu a le d e i p ri n ci p a li ta xa d e l s o n d a g g io i m -5 . p o lle n p e rc e n ta g e d ia g ra m o f se le ct e d t a xa f o r th e c o re i m -5 . 58 calo di pinus e un moderato aumento delle latifoglie, soprattutto di salix e alnus. le concentrazioni polliniche totali restano ancora basse (attorno agli 8000 granuli/g). zona im5-4. la caratteristica più evidente è la marcata espansione di quercus accompagnata dall’incremento delle altre latifoglie del querceto misto come corylus, carpinus t. betulus, tilia, ulmus, quercus t. ilex-coccifera. si osserva, inoltre, l’espansione di fagus. gli elementi non-arborei subiscono una forte riduzione (da circa il 60% della zona precedente a circa il 20% in media). le concentrazioni polliniche registrano un marcato aumento (fino a circa 80.000 granuli/g), ad eccezione della parte basale della zona dove restano ancora basse. zona im5-5. la zona è caratterizzata da una nuova espansione di pinus e una concomitante riduzione di quercus. parallelamente si osserva anche un calo progressivo delle concentrazioni pollinche totali. zona im5-6. questa zona si distingue dalla precedente per l’aumento percentuale di piante legnose coltivate come olea, juglans e castanea. continua l’espansione di pinus e la riduzione di quercus. le concentrazioni sono basse, di poco superiori agli 8000 granuli/g in media. 55.. ddiissccuussssiioonnee e’ possibile suddividere il diagramma pollinico in due porzioni, ognuna comprendente tre biozone. la porzione inferiore è caratterizzata dalla dominanza di elementi non-arborei e da concentrazioni polliniche basse (fig. 4), che indicano un paesaggio non forestato a praterie e steppe. all’interno di questo paesaggio però, si osserva una significativa espansione forestale (im51) a cui segue lo sviluppo di una steppa arbustiva (im5-2) e infine il passaggio a un ambiente più umido indicato dall’espansione delle poaceae e degli elementi acquatici (im5-3). la porzione superiore mostra, invece, la prevalenza degli elementi arborei sulle comunità erbaceo-arbustive con concentrazioni polliniche elevate, testimoniando lo sviluppo di formazioni forestali. in particolare (fig. 4), inizialmente si sviluppa il querceto misto, mentre in seguito esso si riduce per l’espansione di pinus. nell’ultima zona pollinica, la im5-6, tale contrapposizione si accentua e si nota anche l’espansione delle piante legnose coltivate (juglans, castanea, olea, vitis) la cui curva diventa continua. la transizione dalle steppe alle foreste avviene poco più di 10.000 anni fa, cioè all’inizio dell’olocene. le formazioni steppiche delle zone im5-2 e im5-3 sono determinate dalle condizioni climatiche fredde ed aride che si verificarono in europa e nel medio oriente durante il dryas recente. a quel tempo, infatti, in tutta l’area mediterranea orientale e in anatolia si diffusero steppe fredde e aride a dominanza di chenopodiaceae, artemisia, asteraceae e poaceae (bottema, 1995), molto simili per composizione alle steppe delle zone im5-2 e im5-3, come evidenziato anche in altre carote del mar di marmara (mudie et al., 2002; caner e algan, 2002). la modesta ma significativa espansione delle arboree nella zona im5-1 può essere riferita all’«oscillazione interstadiale tardiglaciale» (o complesso allerød/bølling), che segnò la prima ricolonizzazione forestale dopo l’acme glaciale. il passaggio dalle steppe alle foreste segna il drastico mutamento di clima verso condizioni calde e umide dovute all’interglaciale olocenico. il primo segnale di questa trasformazione viene registrato con la culminafig.3 diagramma pollinico sintetico e diagramma delle concentrazioni polliniche totali del sondaggio im-5. synthetic pollen diagram and total pollen concentration diagram for the core im-5. f. fusco & m. ricci lucchi 59 f ig . 4 d ia g ra m m a p o lli n ic o p e r g ru p p i s e le z io n a ti c o s ì c o m p o s ti : q u e rc e tu m m ix tu m : a ce r, b u xu s, c a rp in u s t. b e tu lu s, c . t. o ri e n ta lis , c o ry lu s, c o rn u s cf . m a s, f ra xi n u s, h e d e ra , p h ill yr e a , q u e rc u s, q . t. ile xco cc ife ra , t ili a , u lm u s, a ln u s, s a li x ; a lb e ri m o n ta n i: a b ie s , f a g u s, p ic e a ; p ia n te l e g n o se c o lti v a te : c a s ta n e a , j u g la n s , o le a , v it is ; a rb u s ti : b e tu la , c u p re s s a c e a e in d if f. , h ip p o p h a e , t. j u n ip e ru s ; ig ro -i d ro fi te : c y p e ra c e a e , t. s p a rg a n iu m , l y th ru m , m y ri o p h y ll u m , c f. n y m p h a e a , p o ta m o g e to n . p o lle n d ia g ra m o f se le ct e d g ro u p s. q u e rc e tu m m ix tu m : a c e r, b u x u s , c a rp in u s b e tu lu sty p e , c . o ri e n ta lis -t y p e , c o ry lu s , c o rn u s c f. m a s , f ra xi n u s, h e d e ra , p h ill yr e a , q u e rc u s , q . ile x -c o c c if e ra -t y p e , t ili a , u lm u s , a ln u s , s a li x ; m o u n ta in tr e e s: a b ie s, f a g u s, p ic e a ; c u lt iv a te d w o o d y ta x a : c a s ta n e a , j u g la n s , o le a , v it is ; s h ru b s : b e tu la , c u p re s s a c e a e u n in d if f. , h ip p o p h a e , ju n ip e ru sty p e ; h yg ro h yd ro p h yt e s: c yp e ra ce a e , s p a rg a n iu m -t yp e , l yt h ru m , m yr io p h yl lu m , cf . n ym p h a e a , p o ta m o g e to n . storia paleovegetazionale tardiglaciale-olocenica ... 60 zione delle piante acquatiche durante l’inizio della ricolonizzazione forestale. la comparsa di specchi d’acqua non effimeri era dovuta probabilmente all’aumento della piovosità o alla deglaciazione. l’espansione del querceto misto (im5-4) indica l’ulteriore aumento dell’umidità e della temperatura. si espandono e si affermano anche gli elementi montani, si raggiunge la massima copertura forestale (indicata dall’aumento delle concentrazioni polliniche) e la vegetazione si organizza in fasce altitudinali. i pini, presenti durante la fase più fredda e arida, ora sono quasi assenti. con la diffusione di pinus e la concomitante riduzione del querceto (zona im5-5), la vegetazione cambia di nuovo e assume una fisionomia molto simile all’attuale, probabilmente a causa di una riduzione e/o di una redistribuzione delle precipitazioni annuali verso un clima di tipo mediterraneo. questo è caratterizzato, infatti, dal forte calo delle precipitazioni nei mesi estivi, che determina la tipica stagione secca. nel mediterraneo occidentale, tali condizioni si instaurarono nell’arco di alcuni millenni diffondendosi gradualmente in senso latitudinale da sud verso nord (jalut et al., 1997). più precisamente, il clima mediterraneo si stabilì a una latitudine di 39°-40°n circa 7000 anni fa, e raggiunse i 41°n solo attorno ai 5000 anni fa. se lo stesso andamento è valido anche per il mediterraneo orientale, alla latitudine del mar di marmara, compresa tra 40°n e 41°n, il clima mediterraneo potrebbe essersi instaurato attorno a 6000 anni fa. inoltre, nel periodo compreso tra 7000 e 5000 anni fa, si registra un aumento dell’aridità alle medie latitudini e un calo delle temperature nelle regioni polari (cf. steig, 1999, cum bibl.), mentre per l’europa i dati pollinici di numerosi siti attorno a 6000 anni fa evidenziano un aumento delle temperature (huntley & prentice, 1988), anche se i modelli climatici sono ancora contrastanti (cf. prentice et al., 1998). la curva degli alberi montani resta grosso modo invariata indicando che la fascia montana della vegetazione non subisce grandi modificazioni, mentre sono piuttosto le fasce altitudinali inferiori a risentire dei cambiamenti nel regime e nella distribuzione delle precipitazioni. la zona pollinica im5-6 registra l’intervento dell’uomo sul territorio per la diffusione di piante legnose coltivate. un’analoga diffusione delle piante coltivate si registra nella serie pollinica tardo-olocenica ricavata da un sondaggio eseguito nel lago manyas, nelle strette vicinanze del mar di marmara (leroy et al., 2002). nella turchia sud-occidentale, si assiste alla cosiddetta «fase dell’occupazione di beyşehir» (eastwood et al., 1999), durante la quale si affermano da un lato la pastorizia e dall’altro le colture cerealicole e arboricole, quest’ultime a juglans (noce), olea (olivo), castanea (castagno) e vitis (vite). questa fase iniziò circa 3000 anni fa ma conobbe la sua diffusione attorno ai 2600 anni fa, causando soprattutto una forte riduzione della copertura forestale a favore delle colture. essa terminò attorno al 700 d.c., quando i pini diventarono l’elemento forestale dominante. nella turchia nord-occidentale, la stessa fase di riduzione delle foreste dovuta all’azione dell’uomo iniziò invece 3500 anni fa (beug, 1967; bottema et al.., 1995; cf. mudie et al., 2002). analogamente, nel sondaggio im-5, l’espansione degli alberi coltivati è concomitante alla marcata diminuzione delle concentrazioni polliniche, il che potrebbe indicare una riduzione della copertura forestale. nella porzione sommitale del diagramma, pinus si afferma sopra tutti gli altri elementi. 66.. ccoonncclluussiioonnii la ricostruzione dell’evoluzione paleovegetazionale dell’area prospiciente il mar di marmara orientale ha messo in evidenza sia gli effetti e le caratteristiche delle principali oscillazioni climatiche avvenute dal tardiglaciale ad oggi, sia l’impatto delle attività umane sull’ambiente nel tardo olocene. la più importante modificazione climatica è quella avvenuta all’inizio dell’olocene con lo sviluppo di foreste temperate che hanno sostituito completamente le formazioni steppiche presenti precedentemente. queste foreste sono costituite inizialmente da latifoglie decidue a dominanza di querce che testimoniano il passaggio da un clima freddo e arido ad un clima temperato caldo-umido. successivamente, all’interno delle foreste, si osserva un’ulteriore modificazione con l’espansione di pinus e il conseguente ritiro del querceto misto mesofilo: il clima assume un carattere mediterraneo con relativo calo delle precipitazioni nel periodo estivo e un’accentuata stagionalità. infine, la storia della vegetazione e del clima negli ultimi millenni in questa regione documenta il crescente impatto dell’uomo sull’ambiente, evidenziato dallo sviluppo delle colture e dal conseguente calo della copertura vegetazionale. rriinnggrraazziiaammeennttii si ringrazia l’istituto di scienze marine del cnr di bologna per avere messo a disposizione il sondaggio im-5. lo studio è stato finanziato con fondi murst (40%) 2001 (coordinatore: f. massari). si ringraziano, inoltre, la prof. maria luisa colalongo e il prof. franco ricci lucchi per la lettura critica del lavoro, e i revisori per le preziose osservazioni al contenuto del manoscritto. bbiibblliiooggrraaffiiaa beug h.-j. (1967) contributions to the postglacial vegetational history of northern turkey quat. palaeoecol., 77, pp. 349-356. bottema s. (1995) the younger dryas in the eastern mediterranean quat. sc. rev., 1144 (9), pp. 883891. bottema s., woldring h. & aytyǧ b. (1995) late quaternary vegetation history of northern turkey paleohistoria, 1177, pp. 53-143. caner h. & algan o. (2002) palynology of sapropelic layers from the marmara sea marine geology, 119900, pp 35-46. eastwood w.j., roberts n., lamb h.f. & tibby j.c. (1999) holocene environmental change in southwest turkey: a palaeoecological record of lake and catchment-related changes quat. sc. rev., 1188 (4-5), pp. 671-695. faegri k. & iversen j. (1989) textbook of pollen analysis iv ed., john wiley & sons, chichester, 328 f. fusco & m. ricci lucchi pp. huntley b. & prentice c. (1988) july temperatures in europe from pollen data, 6000 years before present science, 224411, pp. 687-690. jalut g., esteban amat a., riera i mora s., fontugne m., mook r., bonnet l. & gauquelin t. (1997) holocene climatic changes in the western mediterranean: installation of the mediterranean climate c. r. acad. sc., paris, s. ii, 332255, pp. 327334. koreneva e.v. (1971) spores and pollen in mediterranean bottom sediments in: funnell b.m., riedel w.r. (eds.), the micropaleontology of the oceans. cambridge university press, cambridge, pp. 361-371. leroy s., kazancii n., i̇ lerii ö, kibar m., emre o., mcgee e. & griffiths h.i. (2002) abrupt environmental changes within a late holocene lacustrine sequence south of marmara sea (lake manyas, n-w turkey): possible links to seismic events marine geology, 119900, pp. 531-552. moore p.d., webb j.a. & collinson m.e. (1991) pollen analysis. ii ed., blackwell scientific publications, 276 pp. mudie p.j., rochon a. & aksu a.e. (2002) pollen stratigraphy of late quaternary cores from marmara sea: land-sea correlation and paleoclimatic history mar. geol., 119900, pp. 233-260. prentice i.c., harrison s.p., jolly d. & guiot j. (1998) the climate and biomes of europe at 6000 yr bp: comparison of model simulations and pollenbased reconstructions quat. sc. rev., 1177 (6-7), pp. 659-668. roberts n. & wright h.e.jr. (1993) vegetational, lake level, and climate history of the near east and southwest asia. in: wright h.e.jr., kutzbach j.e., webb iii, t. ruddiman, w.e., street-perrott f.a. & bartlein p. (eds.), global climate since the last glacial maximum. univ. of minnesota press, st. paul, mn, pp. 194-220. steig, e.j. (1999) mid-holocene climate change science, 228866,, pp. 1485-1486. stockmarr j. (1971) tablets with spores in absolute pollen analysis pollen et spores, 1133 (4), pp. 615621. zohary m. (1973) geobotanical foundations of the middle east. gustav fischer verlag ed., 2 voll., 739 pp. 61 ms. ricevuto l’11 novembre 2003 testo definitivo ricevuto il 2 marzo 2004 ms. received: november 11, 2003 final text received: march 2, 2004 storia paleovegetazionale tardiglaciale-olocenica ... imp.bedulli& struttura fisica della conoide alluvionale gigante del fiume taro e ricarica degli acquiferi della pianura parmense franco bedulli & renzo valloni dipartimento di scienze della terra, università di parma parco area delle scienze 157a, 43100 parma bedulli@nemo.unipr.it, valloni@unipr.it riassunto: bedulli f. & valloni r., struttura fisica della conoide alluvionale gigante del fiume taro e ricarica degli acquiferi della pianura parmense. (it issn 0394-3356, 2004). i nuovi dati geognostici e stratigrafici di dettaglio raccolti negli ultimi anni hanno consentito di realizzare numerose sezioni geologiche atte a definire la struttura fisica d’insieme della conoide del fiume taro, il suo scheletro sedimentario e le modalità di ricarica degli acquiferi della pianura di parma. l’apparato di conoide è stato diviso in tre settori a struttura fisica nettamente diversa, detti di valle, margine e pianura, con dimensione assiale rispettivamente di 8, 7 e 15 km. i settori di margine e pianura sono separati dalla struttura positiva sepolta di madregolo che controlla la circolazione sotterranea con una soglia imposta a circa -70 m dal p.c. nel settore di pianura si sviluppa un enorme corpo grossolano di sottosuolo, detto anche conoide gigante, con estensione radiale di 15 km e dimensione trasversale massima di quasi 20 km, che giace su un’estesa barriera di permeabilità con tetto a 180.000 anni fa. il controllo tettonico esercitato dai thrust frontali sepolti della catena è a sua volta modulato dal fattore climatico. le principali unità grossolane del corpo di conoide (interpretate come deposte negli stadiali) e le interposte coperture fini (interpretate come deposte negli interglaciali e interstadiali) sono state attribuite agli stadi isotopici marini 1-6 della letteratura. l’alto strutturale di madregolo influenza grandememente le geometrie deposizionali del sottosuolo. sul suo fronte si produce la progressiva espansione del corpo di conoide. sul suo dorso gli acquiferi risultano saldati fra loro a costituire un grande serbatoio che comunica lungostrato con gli acquiferi in pressione posti più all’esterno. la conoide gigante del fiume taro è compartimentata da tre barriere di permeabilità principali che assumono una relativa continuità solo a valle della via emilia e che sulla verticale dell’autostrada a1 vengono intercettate a -40, -80 e -130 metri dal p.c. abstract: bedulli f. & valloni r., physical structure of the taro river giant alluvial fan and parma plain aquifer recharge. (it issn 0394-3356, 2004). using a large set of stratigraphic data, numerous cross-sections of the southern margin of the parma alluvial plain were drawn; they allowed the recognition of the architecture of the taro alluvial fan and the water flow pattern from the surface to the unconfined and confined aquifers. the middle (medesano-madregolo) and outer portion of the alluvial fan system are separated by an anticline, named madregolo high, which controls the groundflow pattern with its impermeable basement uplifted at about -70 m from ground level. in its outer portion the fan has giant dimensions extending up to 15 km axially and up to 20 km normally to the depositional strike. the sedimentation of the middle-late pleistocene alluvium is strongly related to climatic changes. general and local evidence permit the assignment of the tens of meter thick coarse fluvial deposits to cold (glacial) periods and of the meters thick fine alluvium to warm (interglacial) periods. the base of the alluvial fan rests on a laterally continuous confining layer dated 180.000 yr bp. at the intersection taro river autostrada a1 this layer is encountered at -130 m from ground level; confining layers of lesser importance, internal to the alluvial fan body, are encountered at -40 and -80 m from ground level. in front of the madregolo high the coarse sedimentary units (aquifers) of the alluvial fan body are amalgamated. northwards these aquifers expand in thickness and are put under pressure by the intervening confining layers. this indicates that the groundwater flow pattern is from the front of the madregolo high northwards into the unconfined and confined aquifers of the thickest part of the fan. parole chiave: pleistocene superiore, conoide fiume taro, idrostratigrafia, ricarica acquifero parmense. keywords: late pleistocene, taro alluvial fan, hydrostratigraphy, aquifer recharge. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 303-312 1. introduzione il sottosuolo della pianura emiliana è caratterizzato da una successione di apparati di conoide alluvionale, di varia estensione, con apice allo sbocco in pianura dei principali fiumi (idroser spa, 1977). la conoide del fiume taro è di gran lunga la più estesa del margine emiliano e per questo ha assunto la denominazione di conoide gigante (valloni et al., 2003). la presente ricerca ha preso impulso dai recenti lavori a carattere idrostratigrafico sul sottosuolo padano (rer & eni-agip, 1998; regione lombardia & eniagip, 2002), nei quali le alluvioni quaternarie sono ordinate in unità allostratigrafiche padane e poste in relazione ai ben noti cicli astro-climatici del pleistocene medio-superiore. il quadro parmense di tali unità idrostratigrafiche è analiticamente esposto da di dio (2001). la rappresentatività dell’assetto strutturale della pianura di parma e l’imponente raccolta di dati di son304 f. bedulli & r. valloni daggio acquisita dagli scriventi negli ultimi anni rendono oggi utile e possibile dettagliare lo studio della ricarica degli acquiferi freatici e le loro connessioni con gli acquiferi in pressione della media e bassa pianura. 2. inquadramento geografico la superficie della pianura di parma approssima una monoclinale immergente a nord-nordest con pendenza variabile, ovviamente decrescente verso la bassa pianura. la sua porzione sud presenta, in prima approssimazione, pendenze topografiche maggiori del 4,0 per mille dal margine fino alla via emilia e del 1,5-4,0 per mille dalla via emilia all’autostrada a1 (tellini, 2001). il fiume taro bagna il territorio a ovest della città di parma. il suo bacino imbrifero, pari a 1.368 km2 alla chiusura della via emilia, risulta molto più grande di quello dei vicini torrenti baganza e parma. a fornovo termina il tratto intramontano del corso d’acqua che poi prosegue verso nord, stretto dai rilievi collinari, ancora per diversi km (figura 1). nel tratto successivo non esiste evidenza morfologica di una conoide alluvionale proporzionata al rango del bacino di drenaggio del fiume taro. all’altezza di medesano il fiume scorre con lo stile dei canali intrecciati e con una larghezza dell’alveo attuale superiore al km. all’altezza di noceto il talweg diventa pensile sulla pianura adiacente, un carattere che si accentua verso valle. da noceto fino a valle dell’autostrada a1, in sinistra taro si riconoscono le tracce di antichi percorsi del fiume, mentre in destra taro la superficie della pianura è mediamente più bassa di 5 m (perego, 1994). a partire dall’autostrada a1 il fiume cambia stile iniziando a disegnare meandri (petrucci et al., 1983). 3. studi precedenti, impostazione della ricerca i corpi acquiferi della pianura di parma sono stati investigati con particolare intensità a partire dagli anni settanta del secolo scorso. in generale si tratta di studi che soffrono della mancanza di un quadro stratigrafico regionale ed i principali approfondimenti riguardano primariamente gli aspetti idrologici. venzo (1973) presenta i grandi tratti della struttura fisica della conoide del f. taro distinguendo il settore interno (dall’apice di fornovo alla struttura positiva di madregolo), ove il substrato marino è posto a bassa profondità, dal settore esterno ove il substrato marino si abbassa fortemente verso settentrione (cf. figure 2, 3). sulla base di un vasto corpo di dati di pozzo, petrucci et al. (1975) descrivono la complessità geometrica del substrato marino e l’andamento “irregolare degli acquiferi” che solo nella bassa pianura risultano sicuramente compartimentati (cf. figura 3). in alifraco et al. (1992a) è illustrata la geometria del materasso alluvionale controllata dai “corrugamenti del substrato” che determinano una sinclinale interna ed un’anticlinale sull’allineamento monticelli – fontevivo (cf. figure 2, 3). petrucci et al. (1992) trattano a tutto campo l’idrogeologia della pianura parmense e accertano che la ricarica è dovuta “in via prioritaria alle acque di subalveo” che alimentano le ghiaie dell’alta pianura e che distalmente si connettono ad un “sistema acquifero plurifalda”. in ferrarazzo et al. (1997) sono illustrati i risultati di numerose levate piezometriche ed è determinato il volume dell’acquifero che sormonta il substrato marino, considerato come freatico fino all’altezza della via emilia ove, con il progressivo sviluppo di intercalazioni limoso-argillose, ha inizio lo sviluppo di falde semiconfinate. gli studi a respiro regionale degli ultimi anni consentono di formulare un nuovo quadro concettuale dell’evoluzione sedimentaria della pianura parmense che comprende il riconoscimento di un’unità di colmamento della pianura (cf. figura 3), deposta in età pleistocenica terminale ed olocenica (post glaciale), a litologia essenzialmente fine (severi et al., 2002). la deposizione di tale unità comporta la compensazione topografica della pianura tramite “azioni di aggradazione fluviale” (marchetti, 2001) con la conseguenza che la conoide alluvionale del fiume taro manifesta la sua espressione morfologica solo nel sottosuolo. le fasi di forte trasporto di sedimenti grossolani da parte dei corsi d’acqua appenninici sono registrate fig. 1 inquadramento geografico dell’area di studio e traccia delle sezioni delle figure 3 (collecchio-baganzola), 4 (parola-san prospero) e 5 (fontevivo-casalbaroncolo). geographic setting of the study area and trace of the sections of figures 3, 4 and 5. nella struttura fisica dell’edificio di conoide assieme alle fasi di esteso drappeggio della pianura con depositi fini (interglaciali ed interstadiali) che esprimono gli acquitardi più potenti e continui (amorosi et al., 1996; di dio & valloni, 1997). il presente studio si basa su una moltitudine di dati geognostici e stratigrafici di dettaglio che hanno consentito di realizzare numerose sezioni geologiche ad andamento parallelo e trasversale agli assi deposizionali dei corsi d’acqua appenninici del parmense. in particolare il lavoro persegue i seguenti obiettivi: (1) riconoscimento della struttura fisica d’insieme della conoide del fiume taro, (2) definizione del suo scheletro fisico in termini di acquiferi ed acquitardi principali tramite una maglia di sezioni e (3) illustrazione delle modalità di ricarica degli acquiferi della pianura di parma. 4. ricostruzione fisica del sistema di conoide la base dati stratigrafici su cui si fonda la presente ricerca ha tre articolazioni: (1) la banca dati stratigrafici del dipartimento avviata fin dagli anni settanta dal prof. franco petrucci, (2) i sondaggi stratigrafici eseguiti dalla regione emilia-romagna per l’esecuzione della carta geologica 1:50.000 della pianura emiliana e (3) i sondaggi a carotaggio continuo realizzati dal consorzio linea ferroviaria alta velocità. 305struttura fisica della conoide ... 4.1 struttura fisica lo studio del sottosuolo si spinge fino alla superficie di inconformità che identifica il passaggio fra i depositi continentali ed i sottostanti depositi marini, qui definita basamento idrogeologico in senso lato (figure 2, 3, 4, 5), che nei settori alpino ed appenninico viene datata a 800.000 anni fa (carcano et al., 2002). tale superficie, presentata in figura 2 come immagine 3d con vista all’incirca verso est, mette in risalto la caratteristica struttura positiva del basamento idrogeologico che corre sulla verticale dell’allineamento degli abitati di fontevivo, madregolo, stradella e monticelli terme. il database per la costruzione di questa superficie, che può essere intesa anche come “base del continentale”, deriva dai dati di sondaggio per la porzione interna fino al fronte della struttura positiva e, a partire dall’isolinea -200 verso nord, dalla digitalizzazione della superficie base del continentale in scala 1:250.000 (rer & eni-agip, 1998). la deformazione della superficie in questione è congruente con l’allineamento delle strutture sepolte a thrust dell’appennino emiliano (bernini & papani, 1987) e forma una modesta sinclinale allineata sul fronte della catena (figura 3), qui definita “bacino marginale”, sul cui asse i depositi alluvionali hanno uno spessore dell’ordine dei 100-200 m. la delimitazione fisica d’insieme della conoide tardo-pleistocenica del fiume taro è stata principalmente fatta tramite numerose sezioni geologiche origifig. 2 immagine digitale 3d con vista verso est del tetto del substrato marino (pleistocene medio) nell’area di studio. valori di profondità s.l.m. la superficie azzurra approssima il p.c. e interseca la pedecollina all’appoggio delle alluvioni sul substrato marino affiorante. la struttura positiva posta sull’allineamento monticelli terme madregolo fontevivo identifica al suo interno un bacino marginale in cui la copertura alluvionale ha spessore limitato. 3d representation of the top of the marine deposits of middle pleistocene age (depths below s.l.). the monticelli terme madregolo fontevivo tectonic high is related to the thrusting of the apennines front. 306 nali, di cui tre sono parzialmente presentate in questo lavoro (figure 3, 4, 5). in secondo luogo sono state utilizzate alcune sezioni geologiche di letteratura particolarmente significative, i.e., tracciato alta velocità (valloni et al., 2003), tracciati n° 27 e 30 del lavoro irsa (bortolami et al., 1979), tracciato n° 8 dello studio rer & eni-agip (1998) e il tracciato i-i’ del lavoro di petrucci et al. (1975). altre sezioni geologiche utili sono riportate negli studi di alifraco et al. (1992a, b), conti et al. (1999) e sagne (1998). in analogia alla descrizione di beretta et al. (1996) l’apparato di conoide può essere diviso in tre settori, qui denominati di valle, margine e pianura, con dimensione assiale di 8, 7 e 15 km, rispettivamente (figure 1, 2, 3). nel tratto di valle le alluvioni rappresentano un’esile copertura, spessa meno di 10 metri, ampia 1-4 km, mentre nel tratto di margine le stesse colmano la struttura sinclinalica con spessori di 50-100 metri; qui la struttura positiva sepolta di madregolo controlla la circolazione sotterranea con una soglia imposta a circa -70 m dal p.c. nel tratto di pianura si apre il vero e proprio ventaglio di conoide (figura 6) con spessore che supera comodamente i 100 m nell’intorno dell’autostrada a1, spessore che risulta in linea con quelli espressi dai restanti corpi di conoide sudpadani (antolini et al., 1999). 4.2 architettura sedimentaria lo scheletro architetturale della conoide alluvionale è ricavato dalla rappresentazione della distribuzione di due semplici categorie di depositi: sedimenti ghiaiosi, ghiaioso-sabbiosi e sabbiosi (idrogeologicamente poroso-permeabili), che risultano potenziale sede di corpi acquiferi, e sedimenti limosi, limo-argillosi ed argillosi (idrogeologicamente semipermeabili o del tutto impermeabili) che rappresentano barriere di permeabilità (guadagnini et al., 2002). i corpi acquiferi e le barriere di permeabilità principali delle successioni carotate nel sottosuolo della pianura sono stati datati con diversi metodi anche per correlazione con i loro analoghi affioranti (di dio et al., 1997; rer & eni-agip, 1998; sagne, 1998). per le età del pleistocene terminale-olocene sono invece disponibili numerose datazioni assolute col metodo del radiocarbonio (valloni et al., 2003). l’illustrazione del quadro stratigrafico locale si appoggia alla sezione di figura 3, allineata lungo l’asse deposizionale del corpo di conoide tardo-pleistocenico del fiume taro. la successione continentale (allogruppo emilianoromagnolo) è notoriamente suddivisa in due alloformazioni, emiliano-romagnola inferiore ed emilianoromagnola superiore; il passaggio è rappresentato da un’importante superficie di inconformità, affiorante al margine sud della pianura, datata su base biostratigrafica a 470.000 anni fa (di dio et al., 1997). sulla trasversale della sezione collecchio-baganzola di figura 3, l’alloformazione emiliano-romagnola inferiore ha spessore di decine di metri nell’asse del bacino marginale e di ordine metrico al tetto della struttura positiva di madregolo. fig. 3 sezione in destra fiume taro (collecchio baganzola) di inquadramento fisico-stratigrafico del quaternario alluvionale, orientata secondo l’asse deposizionale. il tetto del marino è posto a circa 800.000 a bp mentre il limite fra alloformazione emilianoromagnola inferiore e superiore (gruppo aquifero b ed a, rispettivamente) è datato a circa 470.000 a bp (di dio et al., 1997). i principali acquiferi ed acquitardi della conoide gigante del fiume taro sono attribuibili agli stadi isotopici marini (1-6) di letteratura. hydrostratigraphic longitudinal section (collecchio baganzola) of the taro river giant alluvial fan. major aquifers and aquitards are assigned to the (1-6) marine isotopic stages of the literature. f. bedulli & r. valloni 307 all’interno dell’alloformazione emiliano-romagnola superiore, i corpi acquiferi e le barriere di permeabilità principali che compongono l’architettura della conoide gigante del fiume taro rappresentano l’espressione fisica di una sedimentazione a controllo astro-climatico. le relazioni fra i cicli climatici del pleistocene medio-superiore e i caratteri della sedimentazione fluviale, accertate globalmente (es. mol et al., 2000; vandenberghe, 1995) e localmente (vittori & ventura, 1995; djokic et al., 1999; amorosi et al., 1999; muttoni et al., 2003), consentono di associare la deposizione dei corpi acquiferi e delle barriere di permeabilità principali agli stadi isotopici marini dell’ossigeno. in figura 3 i corpi acquiferi e le barriere di permeabilità principali della pianura parmense, espressi negli ultimi due cicli glaciali (riss e wurm dei vecchi autori), sono stati correlati con gli stadi isotopici marini (si) da 1 (comprendente l’intero olocene) a 6 (martinson et al., 1987). nella sezione di figura 3 risalta la particolare continuità dell’unità fine, su cui si annidano i depositi grossolani dello stadio isotopico 6. da questo momento, in coincidenza con l’instaurazione di un megaciclo sedimentario riconosciuto dal nord al sud europa (kukla & cilek, 1996), nella pianura a ovest di parma si sviluppa un corpo grossolano di particolare imponenza, qui denominato conoide gigante del fiume taro; le unità fini intercalate in tale corpo assumono spessori e continuità significative solo ad una certa distanza dal fronte della struttura positiva di madregolo e comunque a valle del tracciato della via emilia. riassumendo, gli elementi architetturali di particolare rilievo idrostratigrafico sono rappresentati (1) dalla suddetta barriera di permeabilità con tetto a circa 180.000 anni fa, (2) dalla soglia strutturale di madregolo e (3) dalla pendenza delle barriere di permeabilità, che aumenta per quelle via via più profonde. sulla verticale dell’autostrada a1 la barriera di permeabilità deposta al tempo dello stadio isotopico 3 si incontra a circa 40 m di profondità ed ha una pendenza del 0,8 % (0,47 gradi), la barriera di permeabilità deposta al tempo dello stadio isotopico 5 si incontra a circa 80 m di profondità ed ha una pendenza del 1,4 % (0,81 gradi), e la barriera di permeabilità che precede lo stadio isotopico 6 si incontra a circa 130 m di profondità ed ha una pendenza del 1,9 % (1,08 gradi). nelle figure 4 e 5 sono riportate due sezioni fig. 5 sezione immediatamente a sud dell’autostrada a1 (fontevivo casalbaroncolo) trasversale all’asse deposizionale. il corpo di conoide sviluppato all’esterno della struttura positiva di madregolo-fontevivo ha spessore rilevante. all’altezza dell’abitato di fontevivo (ovest) e della città di parma (est) l’accresciuto numero e spessore degli acquitardi esprime un limite di permeabilità. hydrostratigraphic transversal section (fontevivo casalbaroncolo) of the taro river giant alluvial fan. note the relevant thickness of the alluvial fan body and the permeability limits (arrows) to the east and west. fig. 4 sezione lungo la via emilia (parola san prospero) trasversale all’asse deposizionale. il corpo di conoide ha spessore moderato sviluppandosi sul dorso e sul fronte della struttura positiva di madregolo-fontevivo. in corrispondenza dell’abitato di sanguinaro (ovest) e della città di parma (est) il rilevante spessore cumulato degli acquitardi esprime un limite di permeabilità. hydrostratigraphic transversal section (parola san prospero) of the taro river giant alluvial fan. note the moderate thickness of the alluvial fan body and the permeability limits (arrows) to the east and west. struttura fisica della conoide ... 308 distanziate di 3-4 km che illustrano l’architettura della conoide su un taglio pressochè trasversale all’asse deposizionale. risalta in particolare la saldatura dei corpi acquiferi sull’immediato fronte della struttura positiva (figura 4), che genera rapporti di interflow (vigna, 1996) e il vistoso aumento del loro spessore verso nord (figura 5). identicamente, le principali barriere di permeabilità sono sottili e discontinue all’altezza della via emilia e dotate di una certa continuità e spessore, pochi km più a nord, in prossimità dell’autostrada a1. nel settore di massima apertura del ventaglio di conoide, vale a dire sull’allineamento di figura 5 che corre immediatamente a sud dell’autostrada a1, il corpo di conoide del fiume taro presenta un limite ovest all’altezza di fontevivo, ove si chiude in appoggio sulla soglia strutturale (beretta et al., 1999) ed un limite est all’altezza di parma. in corrispondenza di tali limiti i passaggi litologici risultano bruschi e materializzano dei limiti di permeabilità relativamente netti. i depositi sabbiosi di frangia della conoide si interdigitano con quelli di piana alluvionale e di canale dei corsi d’acqua limitrofi che a est sono rappresentati dal paleo-baganza e dal paleo-parma. 5. circolazione idrica dal punto di vista idrogeologico tutta la letteratura è concorde nell’assegnare al subalveo del fiume taro (es. dall’olio et al., 2001; bedulli et al., 2004) un ruolo dominante nella ricarica degli acquiferi della pianura ovest di parma (rossetti, 1976). altrettanto note sono le condizioni dell’entrata in pressione della falda freatica attestate anche da fenomeni di risorgenza delle acque causati da eterogeneità sedimentaria (petrucci et al., 1982). in destra taro la risorgenza avviene immediatamente a nord dell’a1, nell’intorno di baganzola e viarolo, ove lo sviluppo della copertura fine è assai pronunciato. in sinistra taro la fuoriuscita avviene a sud dell’a1, nell’intorno di fontevivo, a causa dell’effetto ostacolo creato da un corpo ghiaioso sovraconsolidato affiorante in corrispondenza della struttura positiva sepolta. nel settore di margine (da medesano-giarola a madregolo) la conoide esprime un modesto carico piezometrico per l’effetto sfioratore creato dalla struttura di madregolo e il limitato spessore (dell’ordine dei 20 m) dei corpi grossolani poggianti sull’importante barriera di permeabilità, con tetto a 180.000 anni fa (figura 3). anche in termini idrogeologici si può quindi dire che la conoide vera e propria corrisponde al suo tratto di pianura. sul dorso della stuttura positiva di madregolo e sul suo fronte, fino a poco oltre la via emilia, si determinano le condizioni di carico piezometrico e di saldatura ed ispessimento dei corpi acquiferi tali da massimizzare la ricarica dal subalveo del fiume taro. nel settore di pianura della conoide la soglia creata dall’alto strutturale di madregolo rappresenta un controllo primario sulle geometrie deposizionali del sottosuolo e sul campo dei flussi idrici sotterranei. sul fronte dell’alto strutturale si ha la progressiva espansione del corpo di conoide, mentre sul dorso dello stesso i corpi acquiferi risultano saldati fra loro. questi ultimi costituiscono un grande serbatoio che comunica lungostrato con gli acquiferi in pressione posti più a valle (conti et al., 1999). la soglia di madregolo esercita un controllo altrettanto importante sulla circolazione idrica relativa agli acquiferi più profondi e compartimentati (a3 e a4 di fig. 6 schema del contesto strutturale e della dimensione fisica dell’apparato di conoide. in rosso l’inviluppo nel sottosuolo della conoide gigante del fiume taro di età pleistocene medio terminale pleistocene superiore. fronti dei thrust sepolti del substrato marino da di dio et al. (1997), semplificato. assi della struttura positiva del substrato marino da petrucci et al. (1975). sketch map of the subsurface extension (red line) of the taro river giant alluvial fan of latest middle to late pleistocene age. f. bedulli & r. valloni rer & eni-agip, 1998) sottostanti la conoide tardopleistocenica del fiume taro. la figura 3 mostra infatti che in corrispondenza dell’alto strutturale anche l’importante barriera di permeabilità (tetto a 180.000 anni fa), che costituisce la base del corpo di conoide, presenta delle discontinuità che consentono transfert idrico e comunicazione lungostrato con gli acquiferi in pressione più a nord che all’altezza della via emilia si trovano fra -70 e -150 m dal p.c. 6. conclusioni la fitta maglia dei dati di sondaggio rende possibile un approccio fisico-stratigrafico al problema della ricarica degli acquiferi nell’ambito della conoide gigante del fiume taro. nel contesto di margine di pianura qui studiato le forzanti della sedimentazione risultano il controllo tettonico, il cui aspetto più evidente è rappresentato dai thrust frontali della catena sepolta, e la sua modulazione da parte del fattore climatico che, fra l’altro, controlla il tasso degli apporti trasversali dai fiumi appenninici. lo schema d’alimentazione idrica della conoide gigante del fiume taro indica una ricarica remota degli acquiferi profondi della media pianura; tale modello potrà essere esteso agli altri settori del margine sud-padano caratterizzati dallo stesso stile deformativo a thrust sepolti. dalla ricostruzione fisica risulta che l’apparato di conoide può essere diviso in tre settori, detti di valle, margine e pianura. nel tratto di valle, esteso 8 km da fornovo a medesano, le alluvioni sono spesse meno di 10 m. nel tratto di margine, esteso 7 km da medesano a madregolo, le alluvioni hanno spessore limitato e la circolazione è controllata dall’alto strutturale che ne costituisce la soglia nord. nel tratto di pianura si sviluppa un ampio ventaglio alluvionale con estensione radiale di 15 km e dimensione trasversale massima di quasi 20 km. l’alto strutturale che corre all’altezza di madregolo rappresenta un controllo primario sulle geometrie deposizionali del sottosuolo e su quelle dei flussi idrici sotterranei. la conoide gigante del fiume taro, intesa sia in senso sedimentologico che idrogeologico, è propriamente rappresentata dal grande ventaglio sedimentario di pianura con apice sulla soglia di madregolo. più propriamente la conoide è costituita dal corpo grossolano, formatosi negli ultimi 180.000 anni, che comprende gli stadi isotopici fino al 6. l’imponente acquitardo su cui poggia la conoide si trova a meno di -30 m dal p.c. in corrispondenza della soglia di madregolo e a ben oltre 100 m dal p.c. dieci km più a nord. le sezioni idrostratigrafiche tracciate secondo l’asse deposizionale (direzione circa nord-sud) mettono in luce importanti saldature fra corpi grossolani sul dorso e sul fronte della soglia e la loro compartimentazione, progressivamente crescente verso nord, ad opera delle barriere di permeabilità. le sezioni tracciate trasversalmente all’asse deposizionale (direzione circa estovest) individuano importanti limiti di permeabilità in corrispondenza del passaggio al dominio di interconoide. il flusso dal corpo idrico superficiale (fiume taro) alla falda freatica e a quella in pressione è grandemente influenzato dalla struttura positiva di madregolo, in corrispondenza della quale i corpi grossolani, saldati fra loro, offrono un ampio serbatoio alla ricarica dal subalveo del fiume taro. sul fronte nord della struttura, l’accentuata pendenza dei corpi sedimentari determina un rilevante carico idraulico che si esplica su corpi sedimentari anisotropi con prevalenza della componente orizzontale della permeabilità. la conoide gigante del fiume taro è compartimentata da tre barriere di permeabilità principali che assumono una relativa continuità solo a valle della via emilia e che sulla verticale dell’autostrada a1 vengono intercettate a -40, -80 e -130 metri dal p.c. queste barriere consentono di identificare tre unità idrostratigrafiche rappresentate dall’acquifero freatico, che proprio nell’intorno dell’a1 entra in pressione, e da due acquiferi profondi alimentati dal fronte della struttura positiva posta a sud. anche gli acquiferi sottostanti l’importante barriera di permeabilità posta alla base della conoide tardo-pleistocenica (complessi acquiferi padani a3 e a4) possono essere, almeno in parte, ricaricati dalle acque di subalveo del fiume taro per transfert idrico nei corpi grossolani amalgamati sul dorso dell’alto strutturale di madregolo. ringraziamenti gli autori sono riconoscenti al dott. nicola calda per il contributo alla realizzazione dello stereogramma di figura 2. lavori citati alifraco g., beretta g.p., bodria a., cattini z., nespoli m., p e c o r a r i m. & z a v a t t i a., (1992a) idrogeologia. in: studi sulla vulnerabilità degli acquiferi 3 alta e media pianura parmense. a cura del consorzio parmense approvvigionamento acqua potabile. pitagora editrice, bologna, 1-35. alifraco g., beretta g.p., bodria a., cattini z., nespoli m., pecorari m. & zavatti a. 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(1995) grain size of fluvial deposits and late quaternary climate: a case study in the po river valley (italy). geology, 23 (8) 735-738. 311 ms. ricevuto il 1° giugno 2004 testo definitivo ricevuto il 23 luglio, 2004 ms. received: june 1, 2004 final text received: july 23, 2004 struttura fisica della conoide ... base late-quaternary alluvial fans in the northern marche apennines: implications of climate changes olivia nesci, daniele savelli , francesco troiani dipartimento di scienze dell’uomo, dell’ambiente e della natura, università “carlo bo”, urbino corresponding author: f. troiani <francesco.troiani@uniurb.it abstract: o. nesci o. et al., late quaternary alluvial fans in the northern marche apennines: implications of climate changes. (it issn 0394-3356, 2010) alluvial fans, fan-like deposits, and piedmont aprons are widespread at mountain-front and foothill sectors of the umbria-marche apennines. they are currently regarded as significant geomophological features strictly dependent on either tectonic or climatic controls. close relationship with tectonics, that are usually stressed by the location of such landforms along fault scarps or other active morphostructures, can be assessed only in the most internal areas of the umbria-marche apennines, dissected by extensional tectonics. conversely, in the piedmont and foothill sectors of the chain, the climatic control on fan deposition and entrenchment become dominant, whereas tectonic constrains can be only indirectly detected. namely, within the umbria-marche apennines, the late quaternary cyclical and systematic episodes of fan deposition and entrenchment at the mouth of tributaries, usually following the main fluvial filling along the trunk valleys, are well known. nonetheless, the main causes that have cyclically controlled the fluvial and alluvial-fan deposition and their subsequent dissection have not been thoroughly investigated yet. in this work we report a general overview on the geomorphological setting of the late quaternary alluvial fans associated with the major fill-terraces that compose the typical staircase of river terraces in the northern marche territory. in particular, for the aggradational suites of the late quaternary fillterraces, we discuss the meaningful stratigraphic relations between the fluvial sediments of the trunk streams and the alluvial-fan deposits originating from the tributaries. we also suggest a possible correlation between the cyclical recurrence of the principal episodes of fluvial aggradation/alluvial-fans formation and dissection and the principal late quaternary climate fluctuations. riassunto: nesci o. et al., conoidi alluvionali tardo quaternarie nell’appennino marchigiano settentrionale: implicazioni paleo-climatiche. (it issn 0394-3356, 2010) conoidi alluvionali tardo quaternarie (isolate e/o coalescenti) sono ampiamente diffuse lungo il fronte montuoso e l’area pedemontana dell’appennino umbro-marchigiano. le conoidi alluvionali sono correntemente considerate come significativi elementi geomorfologici in stretta connessione con la tettonica e/o con controlli di tipo climatico. relazioni molto strette con la tettonica attiva, generalmente evidenziate dalla localizzazione delle conoidi lungo scarpate di faglia o altre morfostrutture attive, sono riconoscibili solo nelle aree interne dell’appennino umbro-marchigiano, interessante da tettonica attiva di tipo estensionale. al contrario, lungo i settori pedemontani della catena è più evidente il controllo climatico sulla deposizione e successiva dissezione degli apparati di conoide alluvionale, mentre il controllo da parte della tettonica può essere riconosciuto solo in parte e indirettamente. lungo l’appennino marchigiano settentrionale, dove è incentrato il presente lavoro, da molto tempo è nota in letteratura la ciclica e sistematica ripetizione, in corrispondenza delle foci dei tributari, di alterne fasi di deposizione e re-incisione di conoidi alluvionali, le quali seguono sistematicamente fasi di aggradazione fluviale lungo i corsi d’acqua principali. nonostante ciò, le cause principali che hanno ciclicamente controllato la deposizione di ampi apparati di conoide e la loro successiva re-incisione, ancora oggi non sono state studiate nel dettaglio. nel presente lavoro viene descritto in alcune aree campione l’assetto geomorfologico delle conoidi alluvionali tardo quaternarie associate ai principali terrazzi deposizionali componenti la tipica successione di terrazzi fluviali all’interno delle principali valli marchigiane settentrionali. in particolare, vengono descritti in dettaglio i rapporti stratigrafici esistenti all’interno dei principali corpi alluvionali, di età compresa fra il pleistocene medio e il pleistocene superiore, fra le sequenze deposizionali di tipo fluviale appartenenti al corso d’acqua principale e quelle di conoide alluvionali presenti alla foce dei principali tributari. gli episodi che hanno portato alla formazione di ampi sistemi deposizionali di conoide alluvionale nei bacini marchigiani settentrionali sono ciclici e seguono sistematicamente le maggiori fasi di aggradazione fluviale lungo i corsi d’acqua principali. i depositi fluviali, fatta eccezione per i settori a ridosso dell’attuale fascia costiera, sono preservati nei principali terrazzi vallivi e vengono generalmente considerati come episodi deposizionali direttamente connessi con i principali cicli glaciali. alla stessa maniera dei depositi fluviali lungo le valli principali, anche la deposizione e successiva reincisione degli apparati di conoide in corrispondenza delle confluenze dei tributari con il corso d’acqua principale sono da ritenersi strettamente connessi con le principali fluttuazioni climatiche tardo quaternarie. inoltre, quando all’interno di un corpo alluvionale terrazzato i depositi strettamente fluviali coesistono con quelli di conoide alluvionale, fra le due tipologie di deposito esistono relazioni stratigrafiche precise e sistematiche. in particolare, i depositi di conoide seguono sistematicamente quelli fluviali; normalmente la transizione fra i depositi di conoide e quelli fluviali consiste in una rapida (fino a 2-3 m di spessore) interdigitazione di facies o, a volte, in limiti netti (anche di tipo erosivo). in ogni caso, i depositi di conoide giacciono generalmente sulla superficie non ancora rimodellata dei sottostanti depositi fluviali. il ripetersi ciclico delle fasi deposizionali ed erosive, l’esistenza di precise e sistematiche relazioni stratigrafiche fra i due depositi e la disponibilità in letteratura, almeno per i depositi più recenti (pleistocene superiore), di numerose età numeriche, hanno permesso di ipotizzare, tenendo anche in considerazione le analisi già effettuata per aree limitrofe e disponibili in letteratura, alcune correlazioni con le principali fluttuazioni climatiche tardo quaternarie. parole chiave: river terraces, alluvial fans, climatic controls, northern marche apennines. keywords: terrazzi fluviali, conoidi alluvionali, controllo climatico, appennino nord marchigiano. il quaternario italian journal of quaternary sciences 23(1), 2010 145-156 146 o. nesci, d. savelli & f. troiani 1. introduction alluvial fans are regarded by current literature as important geomorphological features in mountain-front and foothill settings, usually hinting at alternate phases of aggradations and entrenchment strictly dependent on tectonic and/or climatic control (e.g., bull, 1977; harvey, 1984; harvey et al., 2005; suresh et al., 2007 and reference therein). tectonic controls are commonly regarded as crucial to rule both sediment load and catchment relief, promoting aggradation at the mountainfront and foothills (e.g., davis, 1905; blissembach, 1954; bull, 1964; de celles et al., 1991; hartley, 1993; viseras et al., 2003). equally, climate is considered to play a fundamental role in setting the rate of sediment supply, relief equilibrium, and fan geometry (e.g., lusting, 1965; harvey, 1990, 1996; r itter et al ., 1995; r oberts, 1995). whether at fronts of high-relief areas or at tributary stream junctions, alluvial fans develop where a proper accommodation space for deposition exists, and high sediment loads encounter zones of reducing stream power (harvey, 2004) because of gradient lowering and, above all, of diminished flow confinement (schumm, 1977). moreover, the rate of both sediment supply and catchment erosion is rather related to stream-power which, in turn, is generally a function of precipitation intensity (suresh et al., 2007). hence, the formation and dissection of alluvial fans in a given area is ruled by a complex interlacement of climate-related and tectonic-geologic factors, whose mutual relationships and timing are often hard to unravel. this paper reports some representative examples from the mountain-front and foothill sectors of the adriatic side of the northern marche apennines (fig. 1) in order to emphasize the close relationships in this area of systematic construction and dissection of wide alluvial fans with late quaternary climate changes. 2. river terraces in the marche apennines the marche apennines consist of a ne-verging thrust-andfold belt involving a stratigraphic succession characterized by mesozoic calcareous to marlycalcareous terrains overlain by cenozoic dominantly terrigenous terms (d eiana & p ialli, 1994). a series of sub-parallel ridges and topographic depresfig. 1 location map. a) the study area in the morphostructural framework of the marche region. b) shaded relief map of the study area with location of sample areas described in the text and outcrops shown in figure 5. ubicazione dell’area e dei siti descritti nel testo . a) l’area studiata nel contesto morfostrutturale del territorio marchigiano. b) dtm dell’area analizzata con l’ubicazione delle aree campione descritte e degli affioramenti illustrati in figura 5. sions (fig. 1), resulting from crustal shortening and extension driving the topographic emergence of the chain over the last three million years, generally match, respectively, the main calcareous anticlines and terrigenous synclines (calamita et al., 1991). since the lower pleistocene the area underwent a generalized tectonic uplift (bisci & dramis, 1991; dramis, 1992; d'agostino et al., 2001) gradually achieving its definitive emersion. the modern trunk valleys, characterized by an overall parallel pattern, perpendicular to the structural grain (mazzanti & trevisan, 1978; alvarez, 1999), began to develop since the messinian with the first stages of emersion, but achieved a configuration quite similar to the modern one in the lowermost part of the middle pleistocene, with the definitive emersion of the area (mayer et al. 2003). 147late-quaternary alluvial fans ... the marche region holds an excellent preservation of late quaternary valley terraces and a large number of terrace-alluvium exposures, supported for a long time by a great deal of scientific work (e.g., lipparini, 1939; villa, 1942; selli, 1954; nesci et al., 1995; coltorti et al., 1991; bisci & dramis, 1991; fanucci et al, 1996; wegmann & pazzaglia, 2009). particularly, in the central and northern sector of the marche region, cyclical stages of alluvial fans and piedmont-aprons formation and dissection have been reported in close relation (fig 2) with the valley terraces development (e.g., nesci & savelli, 1986; nesci et al., 1995). the trunk valleys show at least four “orders” of alluvial terraces, ranging from middle pleistocene to upper pleistocene in age (cf. fig. 6), and designated respectively, from the older and higher one, as t1a, t1b, t2, and t3 (nesci et al., fig. 2 composite topographic profiles and cross sections transversal to the trunk-valley axis displaying the arrangement of the principal alluvial-fan deposits in the frame of the major valley terraces in some selected areas of the northern marche apennines. the stratigraphic relationships with the fluvial fills along the trunk valleys are also shown. location of profiles in figure 1b. profili compositi trasversali agli assi vallivi che evidenziano la posizione dei principali depositi di conoide alluvionale nel contesto dei maggiori terrazzi vallivi in alcune aree campione dell’appennino marchigiano settentrionale. sono evidenziati anche i rapporti stratigrafici dei depositi di conoide alluvionale con i sedimenti delle colmate fluviali degli assi vallivi principali. ubicazione dei profili in figura 1b. 148 1990, 1995; fanucci et al., 1996). they are characterized by thick alluvial covers, often exceeding 30 metres in thickness for the only sediments supplied by the trunk-valley, i.e. without the alluvial-fan additional component which, in turn, varies in thickness from a few metres (fine grained fans, nesci & savelli, 1991) up to 25-30 metres (pebbly fans). these terraces are preceded by a complex suite of strath terraces, which, according to genetic mechanisms already described by bull (1992), have been interpreted as related to tectonic factors (fanucci et al., 1996). conversely, as regards the t1a-t3 terraced alluvial suites with which this paper is concerned, they are usually retained to be the result of as many complex, for the most part climatically-driven, aggradation episodes, alternating with likewise complex stages of predominant stream downcutting (e.g., calderoni et al., 1991, 1992; coltorti et al., 1991; nesci & savelli, 1990; 1991; nesci et al., 1995; cilla et al. 1996; coltorti, 1997; wegmann & pazzaglia, 2009). being here t1a and t1b reported as two main distinct terraces, it is worth emphasizing that this subdivision of the traditional “first order of terraces” (cf. lipparini, 1936; villa, 1942 and following authors) in two distinct main stages of terrace development -i.e. with the same “hierarchic range” of the already distinguished 2nd and 3rd “orders of terraces” has been introduced by nesci et al. (1990) just for the metauro and foglia river basins (the two principal catchments of the northern marchean area), where the traditional “first order” revealed to be unsuitable to describe the altimetric distribution of the oldest terrace-alluvium which, as a matter of fact, accounts for two main, distinct stages of terrace formation. as regards the alluvial fill stages related to the principal terrace units, the four main aggradation stages already recognized by nesci et al. (1990, 1995), match in a good way with the principal stages already described by wegmann & pazzaglia (2009) (fig. 6). the principal episodes of aggradation took place during the major stages of late quaternary climatic cooling and, generally, they were not continuous but often complicated by repeated minor episodes of cut-and-fill process (nesci et al., 1995; e lmi et al., 2003). during the intervening late quaternary warmer stages, as well as during the holocene, because of the effect of both climate change and generalized tectonic uplift, stream downcutting and entrenchment exceeded valley aggradation leading to the formation of welldeveloped flights of alluvial terraces (e.g., nesci et al., 1995; di bucci et al., 2003; wegmann & pazzaglia, 2009) which are often exposed along both trunk and tributary valleys, up to 150 meters high above the present valley-floors. 3. alluvial fans in the marche apennines: overview the above delineated comprehensive framework is thus inclusive of the late quaternary alluvial fans of the northern marche area. specifically, in this general context, nesci & savelli (1986, 1990) stressed the systematic recurrence in the cycles of valley-terrace development of peculiar erosional-depositional steps. these steps are repeated quite unvaried in the t1a-t3 cycles of aggradation-dissection, to such an extent that nesci & savelli (1986 and following) called them “guide stages”/“guide deposits” to signify something hinting at a precise position in the cycle itself. hence, the valley fill resulted in a first aggradational step consisting of coarse sediments of braided rivers, even though rather complicated by subordinate cut-and-fill episodes (calderoni et al, 1991) and/or by the local occurrence of different channel-patterns (calderoni et al, 1992). the second step of the trunk-valleys aggradation consists, in turn, just in a tributary-junction related construction of alluvial fans (cf. fig. 2, 3 and 5) above the previous fig. 3 block-diagram showing the of formation (2) and dissection (3) of a wide late pleistocene alluvial fan on the right side of the metauro river valley, c.ca 1 km upstream fossombrone. stages a1, a2, e1 as in figure 6. location in figure 1b. after savelli et al. (1984), simplified. block-diagramma che illustra la formazione (2) e parziale smantellamento (3) di un’ampia conoide alluvionale del pleistocene superiore; versante destro della valle del fiume metauro, c.ca 1 km a monte di fossombrone. le fasi a1, a2. e1 si riferiscono agli eventi descritti in figura 6. ubicazione in figura 1b. da: savelli et al. (1984), semplificato. o. nesci, d. savelli & f. troiani 149 braided river plain or directly on the bedrock (nesci & savelli, 1991). from this perspective, alluvial fan deposits and related piedmont aprons – every so often merging erosional glacis (nesci et al., 2002) are spread throughout the northern marche foothills both in piedmont sectors (savelli & ballerini, 1991; nesci et al. 1993; savelli et al., 1994) and at the junction of tributary catchments with the main valley (nesci & savelli, 1986, 1991). they are part of the depositional suites of the principal alluvialterraces and have been interpreted as climatically-driven landforms related to the late quaternary glacial stages (nesci et al ., 1995). indeed, in the umbria-marche apennines some close relationships between alluvial fan development and tectonics can be stressed in correspondence of either fault scarps or active morphostructures only in the most inner areas (cattuto et al., 2004 and reference therein), dissected by extensional tectonics (lavecchia, 1988 and references therein). on the contrary, in the external sectors of the area the climate control on fan development becomes dominant and the tectonic constraints can only be indirectly detected (savelli et al., 1994; nesci et al., 2002). it is worth underlying that the term “alluvial fan” is used in this paper for alluvial depositional bodies which are directly connected with a specific point of water and sediment input and limited in the downstream (axial) direction. clast lithology highlights a supply from local catchments, while morphometric characteristics of pebbles underline a relatively short travelling distance (fig 5b). as for other places and settings, (e. g., kochel, 1990; mukerji, 1990), the typical fan-shape can be developed or not. most of the fans of the study area do not show the characteristic shape consisting in a downslope radiating segment of cone, because of both the occurrence of confining adjacent fans and physiographic constraints, e.g. narrow valley troughs. in the same place, a progressive confinement of fans is apparent from the older fans to the most recent ones, accounting for an enhancing rate of stream entrenchment which, in turn, can be seen as the result of an increased upliftrate (nesci et al., 2002). the valfig. 4 reconstruction of the uppermost middle pleistocene (a) and late pleistocene (b) alluvial fans at isola del piano, on the north-eastern foothills of monti della cesana calcareous anticline ridge. a strong confinement of the most recent fans is obvious when compared to the coalescing fan-glacis development during the previous cycle. location in figure 1b. after nesci et al. (1993), modified. ricostruzione delle conoidi alluvionali del pleistocene medio finale (a) e del pleistocene superiore (b) nei dintorni di isola del piano, sulle pendici nord-orientali della dorsale anticlinalica calcarea dei monti della cesana. il confronto fra i due diversi eveventi di formazione di conoidi alluvionali mette in evidenza il forte confinamento che caratterizza il ciclo più recente. ubicazione in figura 1b. da nesci et al. (1993), modificato. late-quaternary alluvial fans ... 150 ley narrowing connected with the recent stream-net entrenchment, can be locally so strong that in areas where in earlier fan-formation cycles wide piedmont aprons have formed, in more recent cycles alluvial fans could not develop (savelli et al., 1994). as stated above, whatever the fan-shape, degree of confinement and location, the major northern marche fans are cyclical and are part of the alluvial fill suites of the principal valley terraces. however, this doesn’t mean that a large number of minor alluvial fans cannot form anytime and in any suitable place: widespread, scattered formation of minor fans indeed occurs almost everywhere. it is worth mentioning the large coastalfans (uppermost pleistocene-lowermost holocene) which, with a sea level lower than today, developed close to the modern river mouths because of the removal of huge alluvial masses during the first dissection stages of the upper-pleistocene alluvial plains (di bucci et al., 2003; nesci et al., 2008; calderoni et al., 2008). other examples can be observed, which consist of a wide range of forms every so often active and frequently grading to scree cones (cf. fig 3.3), which and are in relation with both land use and ongoing deep-seated slope gravitational deformations: an example of this latter is the san lazzaro fan reported by francavilla (1976) (cf. fig. 2 f-f’). what follows is a synthetic description of some selected sites, which can be regarded as representative for the whole northern marche sector of both piedmont pediment areas and of tributary junctions with trunk valleys. the sites have been chosen in order to highlight those cases where there are accounts in the same place of a systematic repetition of alluvial-fan deposits in the main fill sequence of each principal terrace, and where relationships with the trunk-valley terrace-alluvium can be easily assessed. the objective is to stress the cyclical recurrence of wide alluvial fan depositional systems, highlighting the stratigraphic relationships between alluvial-fan deposits and fluvial fill of the trunk valleys, and to underline the occurrence of a peculiar sequence of alluvial bodies which can be retained as the result of late quaternary climatic-driven sedimentary and geomorphic processes. 4. alluvial fans in the marche apennines: case studies 4.1 metauro river valley, fossombrone site (figs. 2 ff’, 3 and 4) this site extends for a few kilometres just fig. 5 the characteristic patterns of stratigraphic superposition of alluvial-fan deposits above fluvial sediments in a typical fill-terrace of the northern marchean area. a. sketch displaying the stratigraphic relationships between fluvial (f) and fan (af). b-e. some explicative outcrops and lithologic and morphometric differentiation between fluvial and alluvial fan deposits. location of outcrop areas in figure 1b. le diverse modalità nella sovrapposizione stratigrafica dei depositi di conoide alluvionale sui sedimenti fluviali nella fase aggradazionale di un tipico ciclo di terrazzamento vallivo principale dell’area marchigiana settentrionale. a. schema dei rapporti stratigrafici fra i depositi fluviali (f) e quelli di conoide alluvionale (af). b-e. il contatto in alcuni affioramenti significativi e alcuni elementi di differenziazione fra i depositi fluviali e quelli di conoide alluvionale. ubicazione degli affioramenti in figura 1b. o. nesci, d. savelli & f. troiani upstream fossombrone, where the metauro river crosses the monti della cesana anticline ridge (fig. 1) cutting a rather narrow valley-segment in the calcareous meso-cenozoic units of the umbria-marche succession. three different stages of alluvial fan formation can be observed, related to as many major terracefill events, i.e. t3, t2 and t1 (cf. fig. 6), and each characterized by a thickness ranging from 5 to 15 metres. the late pleistocene fans (t3 fill stage) are preserved at the junction of the widest part of the tributaries with the trunk valley, although a severe dismantling occurred because of both a pronounced lateral erosion performed by the metauro river during the downcutting stage (cf. fig. 3.3), and a strong gravitational instability of a wide sector of the left valley-side. the wide and wellformed holocenic fan already described by francavilla (1976) can also be noticed on the left valley side, where several scree cones and an important landslide accumulation also occur, due to huge, slow deep-seated gravitational movements (pergolini et al., 2001). nonetheless, it is worth underlining that close to the junction of the tributary valley from which this recent fan takes origin, residual patches of an older fan are found hanging on the flanks of the tributary valley in a position clearly correlable with the late pleistocene fan deposits occurring in nearby sectors (e.g. the fan shown in fig. 3). the fans of the uppermost middle pleistocene (i.e. t2 fill stage, cf. fig. 6) are preserved in some small patches on the right side of the metauro valley, resting above fluvial gravels of the t2 fluvial fill and/or directly on bedrock. it is worth emphasizing that, in a general way, fan deposits rest directly on bedrock both upstream along the tributary valley which fed the fan and/or in several internal sectors of the trunk valley, where fill terraces are often substituted by strath terraces. a patch of middle pleistocene alluvial-fan deposits can be observed in a higher position on the right valleyside (fig. 2), resting above the fluvial gravels of the t1 (t1b according with the attribution of nesci et al., 1990). they have a scant morphological emphasis because of strong remoulding, which is at least in part related to the fine-grained nature of the deposit, supplied chiefly by marly and marly-calcareous units. 4.2 metauro river valley, sant’angelo in vado site (fig. 2 v-v’) the site is set a few kilometres downstream of sant’angelo in vado, on the right side of the valley segment that crosses the north-western termination of the catria-nerone anticline ridge (fig. 1). along the valley reach enclosing the site, terraces are preserved at different heights above the modern valley floor which account for four principal fill-stages, the oldest and highest of which has been referred to the t1a (monte proverso terrace, 210 m above the thalweg, according to nesci et al., 1990). the composite profile in fig. 2 crosses the valley in an area where the oldest terrace (t1a) is not preserved, but some previously unreported t1b terraces occur (t1 in fig 2), one of which consisting of both fluvial and alluvial-fan deposits. these deposits, more than 15 meters thick, lie on the top of fluvial deposits at the most external fan-zone, whereas, 151 fig. 6 the principal stages in the development of the main valley terraces in the northern marche apennines: the position of principal episodes of downcutting and aggradation, including alluvial fan formation stages, are shown. plotting against the oxygen isotope curve of lisiecki & raymo (2005), after wegmann & pazzaglia (2009), simplified. le principali fasi erosionali e aggradazionali, con i maggiori episodi di formazione di conoidi alluvionali, nell’evoluzione dei principali terrazzi vallivi dell’appennino marchigiano settentrionale. riferimento alla curva isotopica dell’ossigeno di lisiecki & raymo (2005), sulla base del lavoro di wegmann & pazzaglia (2009), semplificato. late-quaternary alluvial fans ... toward the fan-apex zone, they generally overlay the bedrock. the alluvial fan deposits show a well-preserved top-surface, characterised by a very gentle dipping towards the trunk-valley axis, and covered by a thick decalcified, reddish-yellowish relict soil. more downslope, any patch of alluvial fan deposits related to previous t2 terrace can be observed, likely because of erosional removal, although remains of such deposits occur both upand down-valley. in this respect, it is worth underlying that previous t1b related fan deposits could be preserved because of their topographic location, resting on a local wide divide. conversely, deposits of alluvial fans connected with the t3 fill stage are well preserved in several wide terraces at the junction of tributaries with the trunk valley. 4.3 foglia river valley, colbordolo site (fig. 2 c-c’) this site is located on the right flank of the foglia river valley, roughly between the villages of colbordolo and montefabbri, where the trunk stream crosses an anticline ridge made up mainly of cenozoic marly-calcareous terrains (fig. 1). here, three main fill terraces are preserved, namely t1b (t1 in fig 2), t2, t3. not so different from the already described examples, the fill of each principal terrace consists of both fluvial and alluvial-fan sediments, with preserved thicknesses of fan deposits sometimes exceeding 20 metres. 4.4 monti della cesana piedmont area, isola del piano site (fig. 4) the site is located on the north-eastern foothills of the monti della cesana anticline ridge consisting of mainly calcareous meso-cenozoic terrains (fig. 1). it is an example of alluvial fans finding – at least during some specific cycles of late quaternary fan construction their accomodation space not in an aggraded valley floor, but in a piedmont area wide enough to allow an erosional-depositional glacis to develop. similar examples are diffused in several areas of the central and northern marche region, both on authoctonous terrains (savelli & ballerini, 1991; nesci et al., 1993, 1995, 2002) and in allochthonous ones (guerra & nesci, 1999; nesci et al., 2002). the piedmont area around the village of isola del piano shows wide late pleistocene fill terraces (fig. 4b) characterised by mainly gravel alluvium, averaging 20-25 metres in thickness, supplied by small catchments draining the monti della cesana ridge to the north-east, which accounts for a narrow, sw-ne elongated, confined alluvial fan (nesci et al., 1993, 2002). at higher elevations, several patches of terraced alluvial-fans deposits are found, allowing (nesci et al., 2002) to reconstruct the depositional top-surface with enough accuracy to assess the occurrence of an ancient system of partially coalescent fans. these have been correlated to several scattered remains of a wider erosional surface, hinting at a rather smooth piedmont area shaped in a wide glacis both by fan accretion and by areal erosion (fig 4a). on the basis of morpho-stratigraphic correlation all along the piedmont area and towards the metauro river valley, a reliable attribution to the uppermost middle pleistocene (t2) events of terraces development can be made (nesci et al., 2003). the isola del piano piedmont is also an area where the confinement of alluvial fans in narrow valley troughs during the late pleistocene is particularly clear, a fact that – as mentioned above has been related with an increasing downcutting driven, in turn, by an enhancing rate of uplift. 5. discussion and conclusions during late quaternary, a generalized crustal uplift gradually diminishing in intensity to the north-east, affected the northern marche apennines promoting the formation of river terrace staircases which – including the flights of erosional terraces already described by fanucci et al. (1996) along the main valley sides, reaches heights of up to 300 meters above the present valley-floors (di bucci et al., 2003 and references therein). in such a frame of progressive uplift the major late quaternary cyclic climatic fluctuations (i.e., glacialsinterglacials) can be retained to have driven temporary depositional episodes that promoted the formation of middle pleistocene-upper pleistocene fill-terraces, namely the terrace units referred as t1a, t1b, t2, and t3 (cf. fig. 6) according to fanucci et al. (1996). the flight of valley terraces exposed along the flanks of the main fluvial valleys, generally developed through a complex series of fill and dissection processes, stand for the most evident expression of the so called “rhythmical succession of cycles”, already underlined by lipparini (1936). such “rhythmical succession of cycles”, however, also include other specific morphoevolutive episodes (both erosional and depositional); in particular, among depositional events, the most outstanding and diffuse features are the alluvial-fan deposits, widespreading over the mountain-front and foothills of the umbria-marche apennines (nesci & savelli, 1986, 1990). namely, alluvial fans are an integral part of the alluvial valley-fillings, as they usually associate with fluvial deposits along the trunk valleys (i.e., fluvial sediments are systematically topped with alluvial-fan deposits, cf. fig. 2). on the other hand, at the foothills of the major anticline ridges which characterize the most internal areas, the alluvial-fan sediments/landforms are the only significant alluvial contributors to terrace formation (fig. 4), often coalescing to form typical piedmont aprons (e.g., savelli & ballerini, 1991; savelli et al., 1994; nesci et al., 2002). in the examined areas, the major alluvial fillings are currently considered as climate driven events (coltorti et al., 1991; nesci et al., 1995; wegmann & pazzaglia, 2009). at the same time, the cyclical formation of large alluvial-fan depositional systems at the junction of small tributaries with the trunk-valley and at the foothills of the major anticline ridges of the northern marche apennines, is to be regarded as climate-controlled (nesci et al., 1995). in this context, the geomorphologic analysis of the alluvial fans that directly connect to the major fill terraces exposed within the study area has led to some remarkable considerations, as follows. as shown in figure 2, the formation of wide and thick alluvial fans is systematic and cyclical and is directly connected with the major fluvial fill stages along the trunk valleys. in particular, where both fluvial and fan depositional events occur, the fan deposits systematically follow the fluvial ones, generally overlaying the top of the fluvial fill belonging to the same depositional 152 o. nesci, d. savelli & f. troiani cycle (cf. fig. 6). the most frequent boundaries between the two depositional sequences belonging to the same depositional events are either unconformably erosional or sharp conformable as shown in figure 5. in several cases, however, the boundary results heteropic, with alternation of typical fluvial coarse sediments and locally-derived alluvial fan deposits. where this typology of boundary occurs the thickness of deposits characterized by such alternation is rather low, usually less than 2-3 metres (nesci & savelli, 1991) in a cumulative thicknesses (i.e. fluvial + fan) every so often exceeding 40-50 m. hence, notwithstanding the typology of the stratigraphic boundary, the fan deposits always lie above undissected tops of fluvial sediments (figs. 2, 3). this pattern highlights the occurrence of specific stratigraphic relations (i.e., superposition), and a rather clear chronological succession between the two distinct depositional sequences. namely, in a first time the trunk valley experiences a fluvial filling by aggradational behaviour of the main stream; afterwards, at the junction of the tributaries, alluvial fan systems develop. the t3 terrace has to be regarded as an unavoidable key element to reconstruct the morphoevolutive events in the study area. in fact, the t3 terrace is generally well developed along the northern marche trunk valleys, furthermore it is usually spatially continuous and well constrained by several radiocarbon ages (calderoni et al., 1991; nesci et al., 1995; elmi et al., 2003; calderoni et al., 2008). these latter characteristics, in particular, allow us to define a well constrained morphoevolutive pattern and reasonably correlate the late pleistocene depositional/erosional events with the main late quaternary climatic fluctuations (fig. 6). since a cyclically recurrent suite of peculiar depositional and erosional events characterize each major fill terrace, it is plausible to extrapolate the results obtained for the late pleistocene fill terrace to the older terrace levels (middle pleistocene and uppermost middle pleistocene terraces), as already indirectly demonstrated, for example, in the detailed analysis proposed by wegman & pazzaglia (2009). namely, the t3 terrace becomes an interpretative guide for the analysis of the older fill terraces and, moreover, for the analysis of fill-terrace staircases through the whole umbria-marche area. in this frame, the most striking expression of the late quaternary cyclical depositional events is the cyclical formation of alluvial-fan depositional systems. therefore, the interpretation of the alluvial fan development as climate-driven depositional events despite some dating problems, as at the next point actually can be reasonably projected to the middle pleistocene (t1) and to uppermost middle pleistocene (t2) terraces. on the other hand, alluvial fans are not the only feature fit for this purpose. indeed, among the others, some features that appear to support the assertion of an effective usefulness of some repetitive facies and erosional patterns in both the reconstruction and interpretation of late quaternary morphogenetic cycles, are, for example: i) the systematic repetitiveness of the thickness of both fluvial fills and overlying alluvial fan deposits (cf. bull, 1992); ii) the systematic pattern of the reincision that involve the alluvial fills and, at least in part, the bedrock, promoting the formation of both strath terraces (fig. 2) and ingrown meanders (cf. fig. 3.3). furthermore, in the same perspective the cyclical formation can be also interpreted along the downstream sector of the main northern marche trunk valleys of typical coastal fans merging in a coeval coastal plain, as already suggested by calderoni et al. (2008). it is necessary to underline that for alluvial fan deposits in general, and even more so for those of the alluvial fans of the piedmont sectors of the calcareous anticline ridges which hardly reveal peculiar, clarifying stratigraphic relationships with the alluvial fills of the trunk valleys a very scant number of radiometric ages is available both for the whole marche apennines and for the studied areas. hence, any chronological attribution and/or correlation with other deposits rests more on circumstantial evidence than on analytical data. indeed, calderoni et al. (1991) stressed how the cesano river deposits – but such consideration is equally reliable for the other northern marche rivers only the lower half of the terrace-fill hold wood fragments suitable for dating, since the upper section was lacking in any appropriate materials. on account of this, they performed an indirect computation of the expected age for the upper part of the alluvial suite, reaching an estimate that today sounds quite near to the ages reported by wegmann & pazzaglia (2009). furthermore, some available radiometric ages of alluvial deposits of the marche apennines which have been retained “other” than alluvial fans (e.g. uncorrected 14c ages of 23,500±400 of calderoni et al., 1992 for the upper esino river basin, and 23,500±1200 of mencucci et al. 2003 for the lower foglia river basin) could instead be reasonably referred to fan deposits. as a matter of fact, much work is to be done to achieve – every so often through expensive analytical procedures a larger amount of numeric ages able to detail the chronological attribution and to provide a further advance in genetic explanation of these deposits. however, as targeted by this paper, a detailed field work and the reconstruction of mutual relationships between different sedimentary bodies, between them and certain peculiar erosional events, and between them and specific diagnostic landforms is essential to depict a morpho-sedimentary correlative and evolutive frame as that shown in figure 6, which is capable of eventually being adjusted by further analytical data and/or in which such data can be suitably set. based on the above considerations on the scant availability of numeric chronological constraints for both the upper part of the trunk-stream fills and alluvial fan deposits, a major question regards the fans and aprons of the piedmont areas around the major carbonate anticline ridges. in fact besides lacking in numeric ages, they hardly display obvious stratigraphic relationships with trunk-valley fills. indeed, if their correlation with the fans occurring at the junction of the tributaries on the trunk-valleys were effective, a diachronism with respect to the same trunk-valley fill should result (cf. figs. 2, 5, 6). actually, in certain areas where the downstream termination of some wide piedmont aprons reaches the trunk-valley, a superposition on valley trough fill-deposits is still well recognisable. as an example, the deposits of the coalescing fans of acquaviva, at the foothills of catria-nerone anticline ridge (fig. 1), whose downstream termination reaches the trunk-valley (burano river). here the fan deposits overlay the fluvial valley-fill sediments (savelli & ballerini, 1991), thus hinting at a 153late-quaternary alluvial fans ... downstream extension of the piedmont alluvial-system that expands upon the already formed alluvial-plain of the trunk valley. it is worth emphasizing that the same piedmont alluvium of acquaviva displays a complex evolution which, starting with alluvium supplied from the south-east (i.e. from longitudinal streams), continues with the deposition of huge amounts of alluvium sourced from the south-west (i.e. from the catrianerone carbonate anticline ridge) and thus distributed in an overall transverse direction (savelli & ballerini, 1991). this seems to account specifically for a transition from along-valley aggradation, possibly correlated with the ongoing trunk valley filling-up, to a huge deposition by overburden tributary streams, which joined trunk streams no longer capable and competent to transport the huge sedimentary load supplied from the minor catchments. it is exactly the case of the alluvial fans observed at the junction of tributary streams on the trunk valleys (figs. 2, 3, 5 and 6). similar behaviours, indeed, indicating significant variations in functional interaction between the trunk-stream and its tributaries, also from a conceptual standpoint could strengthen the idea of a chronologic shifting of alluvial sedimentation loci towards the piedmont zones, thus accounting for the stages of generalized development of coalescing fans observed on the foothills of the carbonate ridges. references alvarez w. 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(1942) nuove ricerche sui terrazzi fluviali delle marche. giornale di geologia, serie 2, 16, pp. 5-75 viseras c., calvache m.l., soria j.m. & fernandez j. (2003) differential features of alluvial fans controlled by tectonic or eustatic accommodation space. examples from the betic cordillera, spain. geomorphology, 50, pp. 181-202. wegmann k.w. & pazzaglia f.j. (2009) late quaternary fluvial terraces of the romagna and marche apennines, italy: climatic, lithologic, and tectonic controls on terrace genesis in an active orogen. quaternary science reviews, 28, pp. 137-165. 156 ms. ricevuto il 18 giugno 2009 testo definitivo ricevuto il 5 ottobre 2009 ms. received: june 18, 2009 final text received: october 5, 2009 o. nesci, d. savelli & f. troiani imp.giannandrea i depositi terrazzati affioranti nell’alta valle del fiume ofanto (foglio n. 451 “melfi”, appennino campano-lucano) paolo giannandrea dipartimento di geologia e geofisica, università di bari. riassunto: p. giannandrea, i depositi terrazzati affioranti nell’alta valle del fiume ofanto (foglio n. 451 “melfi”, appennino campano-lucano). it issn 0394-3356, 2004 nell’alta valle del fiume ofanto sono presenti a diverse quote superfici di modellamento fluviale, depositi terrazzati, coperture detritiche e depositi vulcanici. tutti questi terreni sono stati organizzati in uno schema stratigrafico, utilizzando un profilo morfostratigrafico rettificato. sono stati distinti 4 ordini di depositi terrazzati indicativi dell’evoluzione del bacino idrografico del fiume ofanto. il riconoscimento di prodotti vulcanici intercalati ai depositi alluvionali terrazzati ha permesso di proporre una correlazione con le principali unità vulcaniche del monte vulture (supersintemi di monte vulture e di monticchio). in particolare i depositi terrazzati più antichi (pleistocene medio), rinvenuti a quote più alte (terrazzi: ia, iia e ib), sono stati correlati con i supersintemi di monte vulture. i depositi terrazzati più recenti raggruppati nei sintemi di conza della campania (terrazzi: iib e iii) e del fosso dello stroppito (terrazzi: ic, iic e iiic) sono stati correlati con il supersintema di monticchio (pleistocene medio – superiore). il sintema di conza della campania comprende anche depositi vulcanici rilevati in località casa rossa e riferibili ad un centro eruttivo delle ultime fasi di attività del monte vulture (sintema dei laghi di monticchio, età 132±12 ka). depositi vulcanici più recenti correlabili, per età (40.7±8.4 ka) e per chimismo, all’eruzione flegrea dell’ignimbrite campana, sono stati individuati in località ripe del cavallo. questo quadro morfostratigrafico consente di arricchire le conoscenze paleogeografiche del bacino idrografico del fiume ofanto e delle relazioni tra il sistema alluvionale e l’attività vulcanica del vulture. abstract: p. giannandrea, the terraced deposits outcrop in the upper valley of ofanto river (foglio n. 451 “melfi” apennine campano-lucano). it issn 0394-3356, 2004 in the upper valley of ofanto river (north of monte vulture) at different heights, more shaped surfaces, terraced deposits, debris sheets and volcanic deposits are visible. a stratigraphic architecture is reconstructed, using a morphostratigraphic profile. the emerged scheme allows us to distinguish four terraced deposits, related to different evolution stages of the valley. the recognition of volcanic deposits, intercalated in the alluvial conglomerates, makes it possible to propose a correlation with the main volcanic units of monte vulture (monte vulture supersynthem and monticchio supersynthem). the oldest and highest deposits (terraces: ia, iia, ib) are correlated with the monte vulture supersynthem (middle pleistocene), while the younger ones (terraces: iib, iii and ic, iic, iiic) are coeval with the monticchio supersynthem (middle – upper pleistocene). more recent volcanic deposits, found near casa rossa outcrop (conza della campania synthem) are referred to a more recent volcanic activity of monte vulture (132±12 ka b.p.). the youngest volcanic products (outcrop of ripe del cavallo), dated 40.7±8.4 ka b.p., are interpreted as belonging to campanian ignimbrite of the campi flegrei area, according to chemical composition. the stratigraphic scheme, proposed in this paper, gives a new contribution to understanding the morphodynamic evolution of the ofanto river valley and the relationship between the drainage system and the monte vulture volcanic activity. parole chiave: quaternario, correlazioni stratigrafiche, terrazzi alluvionali, depositi vulcanici, fiume ofanto, appennino meridionale. keywords: quaternary, stratigraphic correlations, alluvial terraces, volcanic deposits, ofanto river, southern apennines. il quaternario italian journal of quaternary sciences 17(2/2), 2004, 511-521 1. introduzione in questa nota si presentano dati, inerenti ai depositi terrazzati dell’alta valle del fiume ofanto, derivanti dalle ricerche geologiche condotte nell’ambito del progetto di ricerca carg cnr, per il rilevamento geologico del foglio 451 “melfi” (carta geologica d’italia scala 1:50.000). il foglio (fig. 1) si posiziona lungo il confine campano-lucano dell’appennino meridionale, nella porzione sud-occidentale della valle del fiume ofanto. sul suo bordo nord-orientale affiorano parte dei prodotti vulcanici del monte vulture (de lorenzo, 1900). il fiume ofanto (fig. 1) nasce in appennino campano, a nord dell’abitato di lioni, attraversa la successione argillosa dell’avanfossa bradanica, passando a nord-ovest della piattaforma carbonatica murgiana, e sfocia nel mare adriatico a nord-ovest di barletta. il percorso del fiume, nella media ed alta valle, descrive una forma ad esse con direzione prima est-ovest, poi nord-sud ed infine di nuovo est-ovest; la bassa valle, invece defluisce da sud-ovest verso nord-est con un andamento rettilineo. queste geometrie di percorso sono legate a condizionamenti di tipo tettonico. il tratto appenninico, del fiume (carta geologica d’italia, foglio 451 “melfi”, 2004) si sovrappone ad una struttura tettonica ad attività plio-pleistocenica che segmenta le coltri appenniniche. il tratto terminale, invece, ricalca una discontinuità di primo ordine definita “linea del vulture” (schiattarella et al., 2004) che determina la segmentazione della placca “apula” in subduzione e probabilmente ha favorito la risalita dei magmi che hanno ali512 p. giannandrea mentato il vulcano monte vulture. lungo il fiume ofanto e i suoi due maggiori affluenti (fiumare di atella e di venosa) defluiscono le acque derivanti dal monte vulture con abbondante trasporto solido costituito da detrito vulcanico. i terreni quaternari affioranti nell’alta valle del fiume ofanto e della fiumara di atella e compresi nel foglio melfi (fig. 2), sono rappresentati: da depositi terrazzati rilevati sul versante destro del fiume ofanto, da depositi gravitativi (zanzucchi, 1959) presenti a sud del fiume ofanto e della fiumara di atella e da depositi vulcanici ed epiclastici del monte vulture. il substrato prequaternario è costituito in prevalenza dai depositi argillosi del bacino plio-pleistocenico dell’ofanto; dai depositi miocenici, prevalentemente arenacei delle unità irpine (cocco et al., 1972), e dalle successioni di natura argilloso-calcareo-arenacea delle unità del bacino lagonegrese (scandone, 1975). la cartografia geologica dei terreni quaternari e la relativa suddivisione stratigrafica hanno consentito di ricostruire le relazioni stratigrafiche esistenti tra: i) le unità di modellamento riconosciute a diverse quote rispetto agli alvei attuali, ii) i prodotti dell’attività vulcanica del monte vulture, iii) gli estesi fenomeni gravitativi verificati nel settore meridionale del foglio. in questa nota si riportano i risultati delle ricerche condotte lungo la valle del fiume ofanto, che attraversa l'area del foglio per circa venti km in direzione est-ovest, a nord dell’edificio vulcanico. il criterio stratigrafico adottato è quello delle unità stratigrafiche a limiti inconformi (ubsu, salvador, 1987, 1994). 2. stratigrafia dei depositi terrazzati i depositi terrazzati lungo la valle del fiume ofanto (fig. 2), sono stati rilevati tra gli abitati di calitri e s. andrea di conza e a valle della confluenza del fiume ofanto con il torrente osento. un affioramento isolato è presente in località ripe del cavallo. lungo la fiumara di atella sono stati osservati terrazzi solo in corrispondenza dell’abitato di atella. 2.1. bacino del fiume ofanto le correlazioni stratigrafiche sono state eseguite utilizzando un profilo morfostratigrafico rettificato, tracciato longitudinalmente alla valle del fiume ofanto (fig. 3). le superfici di modellamento, osservabili nell’estremità occidentale del profilo longitudinale, tra gli abitati di calitri e sant’andrea di conza (fig. 2), individuano tre ordini di terrazzi alluvionali (fig. 3; fig. 4). l’unità del primo ordine (ib) comprende due terrazzi (terrazzi dei piani di mesole e dell’incoronata di fig. 2) posizionati entrambi a quota 530 m s.l.m. e rispettivamente a 171 m e 136 m di altezza dall’attuale fondovalle del fiume ofanto. la superficie di modellamento è suborizzontale, nel caso del terrazzo di località piano di mesole, e inclinata di circa 10° in direzione ovest nel caso del terrazzo di piano dell’incoronata. solo a luoghi sono presenti piccoli lembi di conglomerato alluvionale rossastro. le tracce di modellamento dei terrazzi del secondo (iib) e del terzo (iii) ordine, ottenute attraverso l’interfig. 1 bacino idrografico del fiume ofanto catchment basin of the ofanto river. polazione dei tratti di terrazzo conservati, risultano inclinate nella stessa direzione dell’attuale fondo valle del fiume ofanto. dei due profili, quello di terzo ordine (il più recente), raggruppa lembi di terrazzi correlabili fino all’estremità ne della carta. esso è sospeso sul fondovalle attuale ad una altezza di 46 m, in prossimità di conza della campania, 61 m in corrispondenza della zona industriale di calitri e 25 m nell’estremità ne del profilo, descrivendo (fig. 3) una superficie convessa verso l’alto. i terrazzi di terzo ordine sono costituiti da 513i depositi terrazzati ... depositi alluvionali di natura sia conglomeratica che sabbiosa. i conglomerati di colore rosso sono generalmente clasto e fango-sostenuti, con a luoghi, nella parte alta, argille e silt sottilmente laminati. nei terrazzi presenti nell’estremità ne del profilo (fig. 2; fig. 3) si osservano depositi conglomeratici alluvionali in cui tra i ciottoli, di natura prevalentemente sedimentaria e subordinatamente vulcanici, sono visibili anche rari clasti di rocce vulcaniche con vistosi cristalli di flogopite, olivina, pirosseno e lapilli tuffisitici, con al nucleo cristalfig. 2 carta geologica dei depositi terrazzati della valle del fiume ofanto. geological map of the terraced deposits in the ofanto valley. 514 li di pirosseno ed olivina. a questi terrazzi sono anche associati depositi di travertino e colluviali. nel settore occidentale del profilo (fig. 3) ai terrazzi di secondo ordine (iib), visibili solo in questo settore, sono anche da ricondurre le estese coperture detritiche affioranti (fig. 2) sulle argille plioceniche (zanzucchi, 1959), nel territorio compreso fra il fiume ofanto, la fiumara di atella e gli abitati di s. andrea di conza, pescopagano e san fele. si tratta di terreni costituiti da argille ed argille marnose di colore rosso, grigio e verde in assetto caotico, con blocchi calcarenitici sparsi di dimensioni massime di 1÷2 m. queste coperture detritiche poggiano, in più punti, sui depositi alluvionali terrazzati del fiume ofanto, sospesi rispetto al fondo valle attuale di circa 100 m e costituiti da conglomerati clastosostenuti con associate lenti di sabbia di colore rosso bruno. nell’estremità ne del profilo morfostratigrafico (fig. 3), sono distinguibili altri due ordini di terrazzi (iia e ia) i cui depositi sono caratterizzati dalla presenza di terreni vulcanici del vulture, sia in facies primaria che epiclastica. tra i terrazzi di primo ordine (ia) (fig. 3) sono compresi quelli morfologicamente più elevati, sospesi sul fondovalle attuale ad una altezza variabile, da monte verso valle, da 75 m a 65 m. tali terrazzi presentano, tra i depositi conglomeratici alluvionali, (fig. 5) un banco massivo, spesso circa 1,50 m, di cenere e pomici centimetriche di colore chiaro. il terrazzo di secondo ordine (iia) (fig. 3) è costituito da un deposito spesso circa 9 m, delimitato alla base da una superficie erosiva che si approfondisce fino a 35 m dal fondovalle attuale del fiume ofanto. comprende dalla base un deposito conglomeratico alluvionale spesso circa 2 m, a cui si sovrappongono circa 7 m di cenere bruna massiva (lahars). superiormente l’unità è delimitata da una superficie di modellamento che si estende anche alle sottostanti arenarie del flysch miocenico. inoltre, lungo la valle del fiume ofanto, nelle località di casa rossa e di ripe del cavallo, affiorano terreni non riconducibili ai depositi alluvionali terrazzati. in località casa rossa (fig. 3) affiorano circa 10 m di depositi vulcanici costituiti da banchi metrici di brecce massive, con superfici irregolari ed a luoghi depositi epiclastici costituiti da sabbie conglomeratiche p. giannandrea f ig . 3 p ro fil o m o rf o st ra ti g ra fic o lo n g it u d in a le d e lla v a lle d e l f iu m e o fa n to ( d a n o te i llu st ra ti ve d e l f o g lio 4 5 1 “ m e lfi ”, m o d ifi c a to ). l o n g it u d in al m o rp h o st ra ti g ra p h ic p ro fil e o f o fa n to v al le y. ( fr o m e xp la n at o ry n o te s o f th e f o g lio 4 5 1 ”m e lfi ”, m o d ifi e d ). 515 con stratificazione incrociata concava. nella parte centrale della successione si osservano 70 cm di ceneri brune laminate. tra i clasti della breccia sono abbondanti quelli vulcanici, tra i quali si distinguono blocchi di natura subintrusiva con vistosi cristalli di flogopite, olivina e pirosseno. sono presenti, in tutta la successione stratigrafica, lapilli tuffisitici con al nucleo cristalli o aggregati di cristalli di pirosseno ed olivina e rari noduli di lherzoliti. nella zona periferica dell’affioramento sono osservabili strati di cenere con lamine ondulate (surge). in località ripe del cavallo (fig. 2; fig. 3) si osservano, al di sopra di un esteso fronte di cava realizzato nei conglomerati pliocenici (fig. 6), depositi conglomeratico-sabbiosi con intercalati due livelli di cenere vulcanica. i conglomerati sono sia massivi (debris-flow) che con ciottoli allineati (depositi colluviali), mentre le sabbie hanno una forte componente argillosa e presentano sottili lenti di conglomerato canalizzato. il deposito vulcanico di base (fig. 6a) ha uno spessore complessivo di 74 cm ed è massivo nei primi 20 cm e con stratificazione incrociata concava nella restante parte; la porzione superiore è costituita da due strati, di cui quello inferiore chiaro e quello superiore rossastro. le ceneri sono fini e costituite da vetro vescicolato con rari cristalli submillimetrici di pirosseno e lamelle di biotite. datazioni (buettner et al., 2003) 40ar/39ar eseguite su un campione prelevato nella parte massiva del deposito hanno fornito un’età di 40.7±8.4 ka riconducibili, anche dal punto di vista chimico, all’eruzione flegrea dell’ignimbrite campana. il deposito vulcanico superiore ha uno spessore di 40 cm ed è costituito da cenere fine massiva di colore rossastro. 2.2. bacino della fiumara di atella in corrispondenza dell’abitato di atella (fig. 2) sono presenti depositi vulcanici e lacustri correlabili con le vulcaniti di monte vulture (la volpe & rapisardi, 1977), al di sopra delle quali, separati da uno spesso paleosuolo rossastro, si distinguono tre ordini di terrazzi alluvionali (fig. 2) (ic, iic e iiic). i terrazzi del primo ordine (ic) sono costituiti alla base da travertini, con spessore variabile da 2 m a 5 m, a cui si sovrappongono conglomerati alluvionali. i travertini presentano internamente (la volpe & rapisardi, 1977) superfici piane irregolari, impronte di resti vegetali, cianoficee, rari gasteropodi polmonati, microalghe e diatomee. i terrazzi del secondo (iic) e primo (ic) ordine sono entrambi costituiti da conglomerati alluvionali con, in località la cupa, associati travertini. 3. correlazioni stratigrafiche fra i depositi terrazzati e la successione di prodotti vulcanici di monte vulture il monte vulture è l’unico vulcano quaternario posizionato sul fronte esterno dell’appennino ed è i depositi terrazzati ... fig. 4 foto panoramica dell’area di piano di mesole (vedi fig. 2 per l’ubicazione): si distinguono tre superfici terrazzate. panoramic picture of the piano di mesole sector (location in fig. 2), three terraced surfaces are distinguished. fig. 5 deposito vulcanico correlabile con le ignimbriti di fara d’olivo della successione vulcanica di monte vulture. volcanic deposit correlated with ignimbrite of the fara d’olivo of the monte vulture volcanic succession. 516 costituito da prodotti emessi in un periodo di tempo che comprende quasi per intero il pleistocene medio (cortini, 1975; villa, 1986; brocchini et al., 1994; bonadonna et al., 1998). le vulcaniti sono spesso separate da superfici erosive, paleosuoli e depositi epiclastici, che sono stati utilizzati (giannandrea et al., 2002) per la ricostruzione stratigrafica dell’intero apparato vulcanico. in figura 7 si riporta lo schema stratigrafico delle vulcaniti ricostruito per il foglio 451 “melfi” e le possibili correlazioni con le successioni terrazzate riconosciute nelle valli del fiume ofanto e della fiumara di atella. in tale schema i prodotti vulcanici si suddividono nei supersintemi di monte vulture e di monticchio a loro volta suddivisi, rispettivamente, nei sintemi di foggianello, barile e melfi, e nei sintemi della valle dei grigi – fosso del corbo e dei laghi di monticchio. ciascun sintema comprende più subsintemi. il sintema di foggianello (fig. 7) è l’unità stratigraficamente più bassa, poggia su una superficie erosiva modellata sia sulle coltri appenniniche, compresi i conglomerati plio-pleistocenici del bacino dell’ofanto, sia sulla parte alta della successione dell’avanfossa bradanica e comprende i subsintemi della spinoritola, di campanile e di fara d’olivo. il subsintema della spinoritola è costituito prevalentemente da conglomerati alluvionali e dai filoni trachitici ad haüyna di località la spinoritola (giannandrea et al. 2002). il subsintema di campanile comprende depositi esclusivamente vulcanici, sia di caduta che derivanti da flussi piroclastici. al subsintema di fara d’olivo vengono infine riferiti ingenti depositi ignimbritici a composizione tefrifonolitica e trachifonolitica, riconosciuti da crisci et al. (1983) alla periferia del vulcano, e la formazione di una caldera (principe & giannandrea, 2002) verificatasi dopo l’effusione delle ignimbriti, e parzialmente osservabile lungo il margine nord-occidentale dell’edificio vulcanico. una lunga fase erosiva (fig. 7) assimilabile con quella denominata “flaminia” (bonadonna et al., 1998), con formazione, a luoghi, di depositi epiclastici e paleosuoli, separa il sintema di foggianello dal sovrastante sintema di barile che comprende quattro subsintemi. alla base dell’unità si riconosce il duomo fonolitico (hieke merlin et al., 1967, de fino et al., 1982, 86) del subsintema di toppo san paolo, a cui sono sovrapposti depositi piroclastici di caduta e subordinatamente di flusso (la volpe et al., 1988; la volpe & principe,1989, 1991; giannandrea et al., 2002) del subsintema di rionero. il sovrastante subsintema di vulture san michele contiene la spessa successione di prodotti affioranti in corrispondenza dell’edificio centrale di monte vulture. esso comprende lave, depositi di flusso concentrato e subordinati strati di cenere e lapilli di caduta (la volpe et al., 1988; la volpe & principe,1989, 1991). le lave sono più abbondanti in numero e in spessore in corrispondenza dell’area craterica e i depositi di flusso sono costituiti da banchi spessi fino a 10÷15 m con blocchi metrici di lava. il subsintema di ventaruolo, che chiude la serie di prodotti riferiti al sintema di barile, comprende (giannandrea et al., 2002) depositi sia di caduta che di flusso concentrato (guest j.e., et al., 1988); quest’ultimo caratterizzato dalla presenza di cristalli di leuciti centimetriche. nel sintema di melfi sono raggruppate le lave haüynofiriche (hieke merlin et al., 1967) del subsintema del castello di melfi e di piano di croce e i depositi epiclastici del subsintema di piano del gaudo. superiormente in tutta l’area del vulture si distingue uno spesso paleosuolo rossastro (m18, la volpe & principe, 1991) che fossilizza una fase tettonica (schiattarella et al., 2004) durante il quale probabilmente si è verificato il ribassamento di circa 100 m della metà meridionale dell’edificio (la volpe et al., 1984; la volpe & principe, 1994; ciccacci et al., 1999), il collasso del suo quarto sud-occidentale (principe & giannandrea, p. giannandrea fig. 6 foto panoramica di località ripe del cavallo e sezione stratigrafica; a) particolare dei depositi vulcanici osservati nella parte inferiore della sezione. panoramic view of ripe del cavallo locality and stratigraphic section of the referred deposits; a) lauer part section showing the volcanic deposits. 2002) e l’attivazione di numerose faglie orientate in direzione n30-40e. il successivo supersintema di monticchio (fig. 7) raggruppa (giannandrea et al., 2002) i prodotti vulcanici emessi da numerosi piccoli centri (identificati come subsintemi) distribuiti su faglie orientate in direzione n30-40e, quelli raggruppati nel sintema della valle dei grigi fosso del corbo, e in direzione n120 ed estovest quelli raggruppati nel sintema di monticchio. al sintema di monticchio (giannandrea et al., 2002) sono associati i prodotti emessi dai centri eruttivi di lago grande e lago piccolo in cui è stata riconosciuta (stoppa & principe, 1997; stoppa, 2003) una frazione juvenile carbonatitica e melilititica ed abbondanti noduli di origine profonda (lherzoliti a spinello) e lapilli tuffisitici. correlazioni stratigrafiche tra le successioni osservate nelle unità terrazzate del fiume ofanto sono presenti depositi vulcanici che consentono precise correlazioni con i prodotti del monte vulture. il terrazzo di primo ordine (ia) (fig. 3) descritto sul margine ne del profilo morfostratigrafico contiene, intercalato tra le facies conglomeratiche, un deposito vulcanico (fig. 5). questo è interpretabile come unità di flusso piroclastico concentrato del tipo dei pumice and ash flow, correlabile con una delle due unità ignimbritiche di fara d’olivo (crisci et al., 1983), comprese nel subsintema di fara d’olivo (giannandrea et al., 2002) (fig. 7). ciò consente di correlare, con una certa approssimazione, i conglomerati di base di tale terrazzo con quelli del subsintema della spinoritola, mentre la 517i depositi terrazzati ... fig. 7 schema stratigrafico delle unità distinte nell’edificio vulcanico del monte vulture e nei bacini idrografici del fiume ofanto e della fiumara di atella. (da note illustrative del foglio 451 “melfi”, modificato) stratigraphic scheme of volcanic units and fluvial terraced deposits of ofantoriver and atella stream (from explanatory notes of the foglio 451”melfi”, modified). superficie di tetto si correla con la discontinuità di tetto del subsintema di fara d’olivo. pertanto il terrazzo del primo ordine (ia), compreso tra due discontinuità, è correlabile anche nella successione vulcanica alla scala di sintema (sintema di foggianello). la superficie erosiva di tetto, rinvenuta fino alla quota di 35 m sul fondo valle attuale del fiume ofanto, probabilmente si forma con la fase erosiva denominata “flaminia” da bonadonna et al. (1998). in questo modo il terrazzo di secondo ordine (iia) può essere inserito nel sintema di barile, poichè comprende ceneri brune in facies epiclastica (mud flow), riferibili alle ultime fasi di attività del sintema. quest’ultima correlazione viene eseguita perchè flussi gravitativi possono essersi innescati solo dopo la formazione del rilievo di monte vulture, che avviene con la messa in posto dei prodotti del subsintema di vulture – san michele. i depositi vulcanici di casa rossa, in facies di breccia, sono indicativi di un centro eruttivo che, da un dettagliato rilievo (fig. 8), si posiziona a casa rossa. inoltre i caratteri petrografici dei componenti vulcanici del deposito e l’allineamento del centro lungo una struttura orientata in direzione n120 consente di associare questa unità con i depositi dei subsintemi di lago grande e lago piccolo. ciò induce a considerare questi depositi appartenenti a un subsintema (subsintema di casa rossa) compreso nel sintema dei laghi di monticchio, anche se attualmente non si conosce la sua età assoluta. il piccolo rilievo craterico (fig. 9), formato a seguito di questa eruzione, deve aver sbarrato nel settore sud-orientale di figura 8 il deflusso delle acque di un torrente. conseguentemente a monte delle vulcaniti si è formato un piccolo lago, colmato da depositi argillosi (fig. 9c) e da travertino. depositi di travertino si rinvengono (fig. 9b) anche lungo il margine nord-occidentale dell’affioramento, sui depositi di casa rossa fino a raggiungere la superficie di modellamento del terrazzo di terzo ordine. tra i conglomerati di quest’ultimo terrazzo si rinvengono ciottoli derivanti dall’erosione del deposito di casa rossa. tutto ciò porta a ritenere che il terrazzo di terzo ordine sia più recente del subsintema di casa rossa. il deposito più antico delle tre unità terrazzate rinvenute nell’intorno dell’abitato di atella poggia su un spesso paleosuolo rossastro correlabile con il paleosuolo m18 (rinvenuto tra i supersintemi di monte vulture e di monticchio). le tre unità terrazzate sono in rapporto tra loro, per cui è possibile ricostruire una precisa successione stratigrafica a limiti inconformi. si individuano tre subsintemi (fig. 7) raggruppati nel sintema del fosso dello stroppito, compreso a sua volta nel supersintema di monticchio. la serie di terrazzi distinti nel tratto ovest del profilo morfostratigrafico si può raggruppare in due sintemi, di questi i terrazzi inclinati nella stessa direzione del fondo valle attuale sono stati inseriti nel sintema di conza della campania, mentre quelli con inclinazione opposta sono stati inclusi nel sintema dei piani di mesole e dell’incoronata. il sintema di conza della campania comprende il terrazzo di secondo ordine (iib), definito subsintema di s. andra di conza, e quello di terzo ordine, correlabile anche nel tratto ne del profilo morfostratigrafico, definito subsintema di caperroni. i depositi del piccolo bacino di ripe del cavallo (fig. 2, fig. 3, fig. 6) hanno un’età più recente contenendo un deposito vulcanico riferibile all’ignimbrite campana (età: 40.7±8.4 ka), diffusamente affiorante in tutto il territorio dell’italia meridionale (sulpizio et al., 2003). nell’area campana le ignimbriti poggiano su una vistosa superficie erosiva e sono separate dalle sottostanti vulcaniti da un paleosuolo e da depositi colluviali ed alluvionali (bellucci et al., 2003). data l’estesa 518 p. giannandrea fig. 8 carta geologica dell’area di casa rossa (vedi fig. 2 per l’ubicazione). geological map of the casa rossa area (see fig. 2 for location). 519i depositi terrazzati ... fig. 9 profilo schematico e foto panoramica di località casa rossa (a) (vedi figura 2 per l’ubicazione); b) rapporto stratigrafico fra i depositi vulcanici ed il travertino, c) depositi lacustri al di sotto dei travertini. legenda: 1) complesso delle argille marnose, 2) arenarie mioceniche, 3) sintema di barile, 4), subsintema di casa rossa, 5) travertino del subsintema di caperroni, 6) depositi alluvionali del fiume ofanto, 7) breccia, 8) lamine ondulate, 9) faglia inversa, 10) faglia diretta. cross section and pictures panoramic view of casa rossa localtity (a) (see fig. 2 for location); b) stratigraphic relationship between volcanic an travertine deposits, c) lacustrine deposits under traverine. legend: 1) clay marl complex, 2) miocene sandstone, 3) barile synthem, 4) casa rossa subsynthem, 5) travertine of the caperroni subsynthem, 6) alluvial deposit of the ofanto river, 7) breccias, 8) cross-lamination , 9) reverse fault, 10) normal fault. superficie di dispersione delle ceneri (abbraccia tutta l’italia meridionale) e i volumi emessi (consentono di individuare con precisione il deposito anche in aree distali, come quella di ripe del cavallo), ritengo sia ragionevole utilizzare, nella stratigrafia dei depositi quaternari, come limite di supersintema la superficie di base o di tetto di questo deposito. pertanto, per una corretta attribuzione formazionale, del deposito di ripe del cavallo, è opportuno fare riferimento a uno schema stratigrafico definito nell’area della piana campana. 4. evoluzione morfostratigrafica della valle del fiume ofanto ed implicazioni tettoniche lungo la valle del fiume ofanto sono presenti elementi stratigrafici che consentono di tentare una ricostruzione delle tappe evolutive dell’area. in primo luogo la presenza, nel settore ne del profilo morfostratigrafico, dell’ignimbrite di fara d’olivo consente di datare a circa 700 ka lo stazionamento del fiume a una quota compresa fra 75 e 65 m dal fondovalle attuale. anche la presenza dei depositi lacustri nella zona dell’abitato di atella e l’assenza di prodotti vulcanici lungo la fiumara di atella, fanno ritenere che tale valle si sia formata a cominciare dalla fine del supersintema di monte vulture. inoltre la diversa inclinazione rispetto al deflusso attuale del fiume ofanto, della superficie di base del sintema dei piani di mesole e dell’incoronata può essere spiegata con l’attivazione di faglie, che avrebbero fatto basculare verso ovest l’andamento dei terrazzi (budetta et al., 1990), oppure con l’appartenenza di questi terrazzi (fig. 10) ad un corso d’acqua digradante verso ovest. và considerato infine che, in coincidenza del tetto del supersintema di monte vulture, nell’area di studio si registra un aumento di attività tettonica, come ben documentato sull’edificio vulcanico di monte vulture (schiattarella et al., 2004). tale attività probabilmente è stata responsabile del sollevamento generale dell’area, dell’attivazione di faglie inverse retrovergenti (fig. 2) e dell’innesco dell’estese coperture detritiche, distinte nell’area compresa tra il fiume ofanto, la fiumara di atella e gli abitati di pescopagano e san fele. tutti questi fenomeni devono aver fatto aumentare la capacità erosiva del fiume ofanto, che di conseguenza deve aver catturato sia le acque del paleo lago di atella che quelle del paleo lago di lioni, i cui depositi affiorano fuori dell’area studiata in corrispondenza dell’abitato di lioni (fig. 1) (hieke merlin et al., 1971; chiocchini et al., 1981). queste considerazioni consentono di raggruppare anche i terrazzi del sintema di piano di mesole e dell’incoronata nel supersintema di monte vulture, e di far rientrare il sintema di conza della campania nel supersintema di monticchio. infine la superficie convessa verso l’alto del subsintema di caperroni può essere ricondotta all’attivazione di una struttura tettonica verticale posizionata in corrispondenza della zona industriale di calitri. una possibile ricostruzione morfostratigrafica del bacino del fiume ofanto durante il pleistocene medio può essere eseguita, quindi, a livello di supersintema. infatti lungo il fiume ofanto, durante la formazione del supersintema di monte vulture, la valle doveva essere divisa in due bacini idrografici digradanti in opposte direzioni, con lo spartiacque posizionato alcuni chilometri a ovest della fiumara di atella. i terrazzi orientali rappresentano i resti dell’originaria superficie di deflusso del fiume ofanto, mentre quelli occidentali dovevano appartenere probabilmente al bacino idrografico del lago di lioni. bibliografia b ellucci f., s antangelo n. & s anto a., (2003) – segnalazione di nuovi depositi piroclastici intercalati alle successioni continentali del pleistocene superiore-olocene della porzione nord-orientale della piana campana. il quaternario, 16 (2), 279287. bonadonna f.p., brocchini d., laurenzi m.a., principe c. & ferrara g. 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(2002) carta geologica del monte vulture alla scala 1:25.000. 81a riunione estiva della società geologica italiana, torino, 10-12 settembre 2002 (1a bozza di stampa). giannandrea p., schiattarella m., principe c. & la volpe l., (2004) note illustrative del foglio 451 “melfi” della carta geologica d’italia alla scala 1: 50.000, (c.n.r). 92 pp, 24 fig., 3 tab. (inviate per la stampa) guest j.e., duncan a.m. & chester d.k. (1988) monte vulture volcano (basilicata, italy): an analysis of morphology and volcaniclastic facies. bull. volcanol. 50, 244-257. hieke merlin o., la volpe l. & piccarreta g. (1967) carta geologico-petrografica del gruppo vulcanico del monte vulture (lucania). mem. ist. geol. mineral. univ. padova, 26. la volpe l. & principe c. 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(ed) (1994) international stratigraphic guide. international union of geological sciences, trondheim, norway, and geological society of america, boulder, 214 pp. scandone p. (1975) the preorogenic history of the lagonegro basin (southern apennines). in: c. squyres (ed.) "geology of italy", the earth sciences society of the libyan arab republic, 305-315. schiattarella m., beneduce p., di leo p., giano s.i., giannandrea p., principe c. (2004) assetto strutturale ed evoluzione morfotettonica quaternaria del vulcano del monte vulture (appennino lucano). inviato per la stampa su: mem. soc. geol. it. stoppa f. & principe c. (1997) eruption style and petrology of a new carbonatitic suite from the mt. vulture (southern italy): the monticchio lakes formation. journ. volcanol. geotherm. res., 78, 251-265. stoppa f. (2003) consensus and open questions about italian co2-driven magma from the mantle. per. mineral, special issue, 72, 1-8. sulpizio r., zanchetta g., paterne m. & siani g., (2003) a review of tephrostratigraphy in central and southern italy during the last 65 ka. il quaternario 16 (1), 91-108. villa i. m., (1986) cronologia 39ar/40ar del complesso vulcanico del monte vulture. rend simp, 41: 146147. zanzucchi g., (1959) frane pleistoceniche nell’alta valle dell’ofanto. boll. serv. geol. it., 80: 203-208. 521i depositi terrazzati ... ms. ricevuto l’11 maggio 2004 testo definitivo ricevuto il 14 luglio 2004 ms. received: may 11, 2004 final text received: july 14, 2004 imp.digregorio&piras map of the landscape units and geomorphosites of monte arci (sardinia) felice di gregorio & giuseppe piras department of geology, via trentino 51, 09127 cagliari e-mail: geoam@unica.it abstract: f. di gregorio & g. piras, map of the landscape units and geomorphosites of monte arci (sardinia). (it issn 0394-3356, 2005). in the present paper a geomorphosites map is presented in which these sites are inserted in landscape units. the study area is the volcanic complex of monte arci in central-west sardinia. by means of a detailed geomorphological mapping, performed with the aid of photo-interpretation and direct surveys in the field, different types of landscapes have been identified, according to their specific lithological, morphological and evolutive characteristics, that also have determined different types of landuse. it has been possible to distinguish the landscape system of the pliocene volcanites of monte arci that has been further subdivided in the following landscape units: landscape unit of the acid lava’s; landscape unit of the intermediate lava’s; landscape unit of the alkaline trachites; landscape unit of the basic lava’s. the eastern flank is substantially very different and is characterised by the landscape system of the marine miocene sedimentary deposits and the intra-miocene volcanites, with recurrent rounded hills in marly-sandy terrains with discontinuous and sporadic outcropping of infrasedimentary volcanic products mostly in relief. the western flank instead is characterised by the landscape system of the continental plio-quaternary sedimentary deposits, with flat and downhill landforms such as glacis and alluvial mostly inactive cones. inside each of these landscape units several géomorphosites have been identified, mapped and classified according to their genesis, all with own specific scientific, didactic and cultural-tourist interests. this type of analysis and cartographic representation allows to comprise inside these fundamental reference units (landscape units and systems) single punctual geomorphologic elements, showing their genesis in a better way, their spatial distribution and density and the possible relation with their surrounding environment. this kind of map constitutes a valid basic information that allows to evaluate the potential experience of the landscape as a fundamental instrument of knowledge in the territorial and landscape planning and in environmental impact assessment studies. riassunto: f. di gregorio & g. piras, carta delle unità di paesaggio e dei geomorfositi del monte arci (sardegna). (it issn 03943356, 2005). nel presente lavoro viene presentato un esempio di cartografia dei geomorfositi inseriti all’interno delle unità di paesaggio che li contengono. l’area presa in considerazione è quella del complesso vulcanico del monte arci nella sardegna centro-occidentale. tramite un dettagliato rilevamento geomorfologico, condotto con l’uso della fotointerpretazione e di rilevamenti diretti in campo, nell’area sono state identificate alcune tipologie di paesaggio in base agli specifici caratteri distintivi geolitologici, morfologici ed evolutivi, ai quali corrispondono anche ben definite tipologie di utilizzazione del suolo. in sostanza, è possibile distinguere nel monte arci il sistema di paesaggi delle vulcaniti plioceniche che, a sua volta, può essere classificato nelle seguenti unità: unità di paesaggio delle lave acide; unità di paesaggio delle lave intermedie; unità di paesaggio delle trachiti alcaline; unità di paesaggio delle lave basiche. da questo si differenzia sostanzialmente il settore orientale, caratterizzato dal sistema di paesaggi dei depositi sedimentari marini miocenici e delle vulcaniti intramioceniche, contraddistinto dalla ricorrenza di morbide forme collinari concave alla base e convesse verso l'alto, in terreni marnoso-arenacei con affioramento discontinuo e sporadico, generalmente in emergenza, dei prodotti lavici infrasedimentari. il settore occidentale è, invece, caratterizzato dal sistema di paesaggi dei depositi sedimentari continentali plio-quaternari, con forme pianeggianti e pedemontane, quali glacis e conoidi alluvionali, per lo più inattive. all’interno di ciascuna unità di paesaggio sono stati identificati e cartografati i geomorfositi presenti distinti in base al processo genetico e al livello di interesse scientifico, didattico e turistico-culturale. questo tipo di analisi e di rappresentazione consente di ricomprendere all’interno delle unità fondamentali di riferimento (unità di paesaggio e sistemi di paesaggi) i singoli elementi geomorfici puntuali, lineari o areali, di esplicitarne meglio la genesi, la distribuzione e la densità nello spazio geografico. questo metodo di analisi e rappresentazione costituisce una valida base conoscitiva per valutare il potenziale di esperienza del paesaggio, nella pianificazione territoriale e paesaggistica e negli studi di valutazione di impatto ambientale (via). keywords: geomorphosites, landscape units, landscape systems, central-west sardinia, monte arci, valorisation. parole chiave: geomorfositi, unità di paesaggio, sistema di paesaggi, sardegna centro-occidentale, monte arci, valorizzazione. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 267-273 268 f. di gregorio & g. piras 1. introduction in the present paper a géomorphosites map is presented in which these sites are inserted in landscape units. the study area is the volcanic complex of monte arci in central-west sardinia. the landscape unit represents a fundamental taxonomic unit in a methodological approach of mapping of the resources of a territory based especially on its physical characteristics (clemente, 1987; di gregorio, 1987; piacente et al., 2000; poli et al, 1994; romani, 1994; turri, 1979); this allows to describe with greater detail the areas with a recurrent lithological, morphological and pedological pattern that are genetically related, or else geographical units with specific, distinctive and homogeneous characteristics of formation and evolution (tricart & kilian, 1979; piacente, 1999; romani, 1994; sestini, 1963). this approach also permits to individuate significant elements of the landscape (panizza, 1988), as has clearly been demonstrated by earlier experiences such as the territorial landscape plan of the emilia-romagna region (1987). the landscape units are generally considered singularly or in association with other units forming systems with peculiar genetic or evolutive connections; in other cases the landscape units are subdivided in single components depending on the complexity of the study area and of the desired cartographic detail (fao, 1983). the recognition of landscape units and systems is possible by means of methods for the territorial analysis of vast regions, essentially based on remote sensing techniques or on aerial photo-interpretation. the principal fundament of validity of this type of approach relies on the fact that the landscape configuration, using geomorphologic analysing method, is the easiest characteristic of the physical attributes of a territory to recognise, classify and represent. in particular, according to the lithologic-morphologic criteria it is possible to individuate different fundamental landscape units all of which give birth to spatial entities characterised by a distinct set forms and different from others on the base of the single constituting components. in this manner a classification of the geographic space is configured, principally based on the analysis of the geological constitution and the characterising landforms, considering that these are the expression of the evolution and of a dynamical earth surface that is realised by the interference of natural and human processes and phenomena. regrouping the landscape units with homogeneous genetic and evolution characteristics it is possible to define landscape systems. thanks to the recognition and the classification of these distinct litho-morphological units it is thus possible to make an easier reading of the territory and a more immediate and accurate qualification of the natural resources, in particular of those that constitute the peculiar physical traits because collocated in the same spatial context; in contemporary it is possible to individuate the situations of interference between natural and human factors, or a combination of these, for a more rational use and tutelage of the same resources and a better insertion in eventual settlements and infrastructures in the natural and human existing landscape (clemente, 1987). this methodology has been applied in the monte arci area, in central-west sardinia, collimating particularly the attention on the relationship between geosites and géomorphosites, landscape units and systems (tab. 1). 2. geological and geomorphological aspects of monte arci monte arci is an important tertiary and plioquaternary volcanic complex characterised by a wide variety of effusive rocks and interesting structural or residual landforms derived from ancient palaeogeographic and palaeoclimatic events. the products of the volcanic activity that can be found on monte arci are referable to two different chronological events, each of which have distinct precise volcanologic and geodynamic characters. to the intra-miocene volcanism, referable to the tectonic evolution of the western mediterranean (cherchi & montadert, 1982) are correlated mostly discontinuous outcrops intercalated in the marly-arenaceous miocene sediments of marmilla (maccioni, 1969; 1974), constituted of basic rocks with calco-alcaline affinities, related to a submarine volcanism dated 19÷5 my (savelli, 1975; di paola et al., 1975). such outcrops are constituted, from bottom to top, by submarine pillow lava’s with infrasedimentary hyaloclasts and monogenetic breccia of pillow lava’s with minor presence of hyaloclasts. to the late-pliocene cycle the emission of the lava’s that have originated the volcanic complex of monte arci during distensional phenomena of the continental sardinian plate and the formation of the tectonic graben of campidano are attributed, with basic, intermediate and acid rocks related to subaerial volcanism. radiometric dating (belluomini et al., 1970; belluomini & taddeucci, 1970; savelli, 1975; di paola et al., 1975; bigazzi et al., 1976; beccaluva et al., 1985; montanini, 1992; montanini & villa, 1990, 1993) has allowed to date the pliocene volcanic activity between 5 and 2.6 my. the succession of volcanic products recognised by several authors (di paola et al., 1975; beccaluva et al., 1975, 1977; assorgia et al., 1975; 1976), from bottom to top is represented by: acid lava’s, constituted of rhyolite-rhyodacite flows with transition of lithoid facies to perlite-obsidian facies with associated pyroclastic levels; intermediate lava’s, mainly dacitic and subordinately andesitic, with evident slabby fissuring; alcaline trachites, sometimes passing to vitrophyric facies; basic lava’s, separated in basaltic andesites, basalts with an alkaline chemistry and subalcaline basalts; the plio-quaternary continental sedimentary deposits are mainly composed of: conglomerates, sands and more or less compact clays, mainly composing alluvial cones and glacis (ancient alluvium auct.); recent and present alluvium along river beds. altogether monte arci has a typical form of elliptic ridge elongated in n-s direction that reaches its highest altitude at the neck named trebina longa (812 m a.s.l.). the western sector that overviews the campidano is composed of volcanic flows, mostly rhyolite, deeply cut by valleys that flow into the plain. the eastern sector is characterised by a morphology of plateau with different almost horizontal plains limited by rocky cliffs and steep surfaces that form a clear contrast with the sweet hills of the marmilla. 269map of the landscape units ... 3. the landscape systems and units of monte arci to facilitate the individuation of the géomorphosites, according to the definition given by barca & di gregorio (1991) and by panizza & piacente (1989), on monte arci firstly the territory has been subdivided in landscape units and systems (fig. 1). in more detail, using lithological and morphological criteria the main tab. 1 systems and landscape units of monte arci. sistemi e unità di paesaggio del monte arci. landscape system landscape unit location general morphology summary of main physical features 1 plio-quaternary recent and modern riu florissa, more or less vor enclosed valleys sedimentary-continental alluvium of main river riu tumboi, u-shaped enclosed waterfalls deposits beds gora tappoi valleys glacis and alluvial pranu tiria, pranu forru, largely inactive glacis glacis fans madala, mandronis, and alluvial fans alluvial fans sa giara, pira inferta s’argioledda 2 pliocene volcanic basic lava flows pranu terra, pranu near horizontal or basalt plateaus rocks mallu,pranu santa lucia, gently undulating temporary wetlands su tasureddu, campu basic lava plateaus dykes serrau, apruna, acqua and lava flows necks marzana, arrideli, lava domes benazzeddus, corona column jointing su pardu, pranu murta, pranu pira, pranu sibiriu trachytic lava flows punta quebiois, is benas rugged, porphyry small cavities and serra arruidroxiu, punta and intensely tafoni s’orziada, punta masoni honeycomb-weathered slightly enclosed perdu, rocce su rock outcrops valleys colombariu near vertical walls intermediate lava costa pisu, braxelogu, gently inclined lava lava flows flows (andesite and pranu piccinu, flows often fractured fractures with slab dacite) cuccuru mattivi, conca and slab-like, like geometry mraxi, bruncu su copiu surrounded by near near vertical rock vertical rock walls walls enclosed valleys pseudo-karst cavities waterfalls acid lava flows punta laccu sa vitella, rugged landforms enclosed valleys (rhyolitic, rhyoliticgenna spina, perdas with steeply inclined pyroclastic rhyodacitic) often in urias, punta nicola slopes, sharp breaks sequences perlite-obsidian pani, conca s’ollastu, of slope and obsidian deposits facies, sometimes punta su cantareddu, enclosed valleys tafoni associated with mt. sparau perlite quarries pyroclastic strata 3 miocene sedimentary marly-sandy cea pedrixi, repetitive, gently repetitive rolling marine deposits and sediments sa spendula, rolling hills on hills intra-miocene intercalated with truncheddu, cannisone, marly-sandy terrains enclosed valleys volcanic rocks submarine basic pranu espis, serra with discontinuous pillow lavas pillow or brecciated craboni, pala sa murta, and sporadic outcrops waterfalls lavas, with su entosu, santa maria, of intrasedimentary associated corona fraus lava products hyaloclastites 270 f. di gregorio & g. piras 1 2 3 1 1 1 2 2 2 2 2 2 2 3 3 3 villa verde pau ales pitzu tenuru zeppara p ra nu e sp is p.ta pizzighinu apruna corongiu sitzoua rocca tressa is m u ru s trebina longa conca mraxi trebina lada p.ta trunconi p a ri s d e b e n a s is b e n a s p.ta perda de pani cuccuru mattivi pranu pira curcuris pompu masullas morgongiori p ra n u i s f o g a ia s conca cannas rocce su colombariu p ra n u s ib ir iu siris c o ro n a f ra u s s u p ia li uras villaurbana p ra nu m al lu p ra m a rr a d a c o sta p isu p ranu terra monte 'e cres ia tiria pranu tiria c a m p u t o m a su pranu santa lucia campu forru pira infe rta mason gius b r a x e l o g u p.ta corongiu mela p.ta pranu staddas genna spina genna cruxi perdas urias sant'anna escovedu usellus p ra n u m u rt a 2 1 1 1 2 p.ta su zippiri conca s'ollastu cuc.ru aspru landscape system of the pliocene volcanites acid lava's, constituted of rhyolite-rhyodacite flows with transition of lithoid facies to perlite-obsidian facies with associated pyroclastic levels intermediate lava's, mainly dacitic and subordinately andesitic, with evident slabby fissuring alcaline trachites, sometimes passing to vitrophyric facies basic lava's, separated in basaltic andesites, basalts with an alkaline chemistry and subalcaline basalts landscape system of the continental plioquaternary sedimentary deposits conglomerates, sands and more or less compact clays (ancient alluvium auct.) debris recent and present alluvium along river beds, alluvial cones and glacis landscape system of the marine miocene sedimentary deposits and the intra-miocene volcanites marly-arenaceous miocene sediments of marmilla; submarine pillow lava's with infrasedimentary hyaloclasts and monogenetic breccia of pillow lava's with minor presence of hyaloclasts. limit of landscape system faults and fractures town geomorphosites conventional signs legend 1 2 3 fig. 1 – map of the landscape units and systems of monte arci carta dei sistemi e unità di paesaggio del monte arci. 271 geomorphological units have been identified, all of which give rise to a landscape with precise, distinctive and homogeneous genetic and evolutive characters. following these criteria the landscape systems have been recognised and, for each of these, have been distinguished the landscape units and also the single physiographic components present in them. practically, from the performed research using detailed field work and photo-interpretation, it has been possible to distinguish the landscape system of the pliocene volcanites of monte arci that has been further subdivided in the following landscape units: landscape unit of the acid lava’s, characterised by an articulated and uneven morphology especially where massive rhyolites crop out, with steep sides and clear breaks of slope where the less resistant perlite-obisian facies are surfacing and the presence of a well developed fluvial network, typical of the western flank; landscape unit of the intermediate lava’s, characterised by a plateau morphology on the lava flows recognisable by the slabby fissuration of the rocks; landscape unit of the alkaline trachites with landforms prevalently related to meteoric subaerial processes with hollows and tafoni; landscape unit of the basic lava’s characterised by table-like morphologies bordered by vertical cliffs or steep slopes. from these units the eastern flank is very different, characterised by the landscape system of the marine miocene sedimentary deposits and the intramiocene volcanites, characterised by recurrent rounded hills in marly-sandy terrains with discontinuous and sporadic outcropping of infrasedimentary volcanic products mostly in relief. the western flank instead is characterised by the landscape system of the continental plio-quaternary sedimentary deposits, with flat and downhill landforms such as glacis and alluvial mostly inactive cones. 4. the geomorphosites inside the landscape units of monte arci many géomorphosites have been identified (tab. 2) that represent a high didactic and scientific value, as testimonies of particular past and still ongoing evolutive geological and geomorphological processes (barca et al., 1997; di gregorio & piras, 1997). some of these géomorphosites can be considered as single or isolated elements (sa perda sperrada, the columnar fissuring of is aruttas santas, the andesitic megapillow of gutturu forru and the isolated outcrops of pillow lava’s, the volcanic necks of trebina longa and trebina lada, the waterfalls of sa spendula and su fustiolau) others are better identified as linear morphotypes (the cliffs of conca mraxi and the pyroclastic levels at their foot, the river riu tumboi and its tributaries, the emerging basaltic dykes of is murus, corongiu sitzoua, acquafrida, paris de benas, sa dispensa) or as aerial more or less relevant sites (the basaltic plateau of pranu santa lucia and the temporary wetlands called paulis on its summit, the tafoni of is benas, rocce su colombariu and conca s’ollastu, the steppe-like environments of campu forru and pranu tiria). some of these sites (the hypogean neolithic burial of su segretu de sa conch’e s’omini, the nuragic hypogean temple of sa grutta de is coambus, the obsidian sites of perdas urias, conca cannas and tzipaneas) have a great archaeological interest, as testimonials of the life and the artefacts of the ancient populations that have lived in this territory, founding the seam of the nuragic culture started with the industry of the obsidian that took up the confront with many other mediterranean cultures. 5. conclusions geomorphosites are among the multiple and complex environmental components of the landscape that need to be studied and on which whatever territorial and environmental planning should be based, occupying a fundamental role for their value as a non renewable resource, sometimes unique for their intrinsic characteristics. possible risks for the integrity or the complete destruction of this heritage can be avoided only by a detailed territorial analysis founded on the impact assessment of the projects regarding the occupation of the soil, the use of the natural resources and the urbanisation. by means of a detailed geomorphological mapping, performed with the aid of photo-interpretation and direct surveys in the field, different types of landscapes have been identified at monte arci (central-west sardinia), according to their specific lithological, morphological and evolutive characteristics, that also have determined different types of landuse. inside each of these landscape units several géomorphosites have been identified, mapped and classified according to their genesis, all with own specific scientific, didactic and cultural-tourist interests. this type of analysis and cartographic representation allows to comprise inside these fundamental reference units (landscape units and systems) single punctual geomorphologic elements, showing their genesis in a better way, their spatial distribution and density and the possible relation with their surrounding environment. this kind of map constitutes a valid basic information that allows to evaluate the potential experience of the landscape as an fundamental instrument of knowledge in the territorial and landscape planning and in environmental impact assessment studies. the cartographic work of recognition of the landscape units and systems has allowed to identify various géomorphosites. the adopted analysis and the evaluation of these géomorphosites inside a physiographic reference unit permits to reveal a predominance of sites in the landscape units of the tertiary volcanic rocks, showing a more relevant geodiversity and a higher multiple value (di fidio, 1990) of landscape elements that can be used for e recreational experience of the landscape by geotourism. map of the landscape units ... 272 f. di gregorio & g. piras tab. 2 – geomorphosites of monte arci. i geomorfositi del monte arci. landscape system of the pliocene volcanic rocks name municipality location i.g.m. reference genetic rock type genetic classification definition basalt flows landscape unit 1 trebina longa morgongiori porteddu murus 539 iv mk78300288 volcanic basalt volcanic necks trebina lada 2 pranu santa lucia villav. usellus pranu santa lucia 529 iii mk82450798 volc.-struct. basalt volcanic plateau 3 paulis del pranu santa lucia villav.usellus pranu santa lucia 529 iii mk83050950 lacustrine basalt temporary basins 4 sa perda sperrada masullas perda sperrada 539 iv mj79039546 struct.-meteoric basalt morphosculpture 5 “is murus” dyke marrubiu is murus 539 iv mk76930385 volcanic basalt outcropping dyke 6 “corongiu sitzoua” marrubiu corongiu sitzoua 539 iv mk76930495 volcanic basalt outcropping dyke dyke 7 “acquafrida” dyke ales acquafrida 529 iii mk78200593 volcanic basalt outcropping dyke 8 “paris de benas” morgongiori paris de benas 539 iv mk78340113 volcanic basalt outcropping dyke dyke 9 “sa dispensa” dyke palmas arborea sa dispensa 529 iii mk77810878 volcanic basalt outcropping dyke 10 is aruttas santas villaurbana is aruttas santas 529 iii mk78631228 volc. – struct. and.– basalt. columnar jointed basalt columns basalt intermediate lava flows landscape unit 11 “cliffs” at conca ales pau conca mraxi 539 iv mk80750245 struct. slope rhyolite sheer volcanic mraxi morgongiori dacite walls 12 “sa spendula” ales cadresa 539 iv mk80250338 fluvial – struct. dacite waterfall waterfall 13 riu tumboi and villaurbana riu tumboi 529 iii mk80051245 fluvial – struct. dacite – and. small fluvial valleys affluents 14 sa grutta de is morgongiori punta santu marcu 539 iv mk79950093 anthropogenic dacite natural cavities coambus hypogeum temple ipogeo 15 su segretu de sa villaurbana braxelogu 529iii mk80101043 anthropogenic dacite natural cavities conch’e s’omini hypogeum alkali trachitic lava flows landscape unit 16 is benas morgongiori is benas 539 iv mk79250150 meteoric trachyte honeycombed rock 17 rocce su masullas rocce su 539 iv mj77989695 meteoric trachyte honeycombed rock colombariu colombariu acid lava flows landscape unit 18 conca s’ollastu marrubiu conca s’ollastu 539 iv mk73550217 meteoric rhyolite honeycombed rock morgongiori 19 layers of ales conca mraxi 539 iv mk80750245 volcanic pyroclastic pyroclastic pyroclastic rock morgongiori rock sequences 20 conca cannas masullas conca cannas 539 iv mj77389713 volcanic rhyolite obsidian deposit obsidian deposit 21 perdas urias pau perdas urias 529 iii mj80360621 volcanic rhyolite obsidian deposit obsidian deposit sennixeddu 22 tzipaneas marrubiu tzipaneas 539 iv mk76530371 volcanic rhyolite obsidian deposit obsidian deposit landscape system of the miocene marine sedimentary deposits and intramiocene volcanic rocks 23 “fustiolau” pau truncheddu 539 iv mk80930684 fluvial – struct. marl – aren. waterfall waterfall 24 megapillow at masullas gutturu forru 539 iii mj83509418 volcanic andesite andesitic gutturu forru megapillow 25 – outcrops of masullas siris santa maria 539 iv mj79089557 volcanic basalt – and. pillow lava pillow lava morgongiori pala sa murta landscape system of the plio-quaternary continental sedimentary deposits 26 – steppe palmas arborea campu forru 529 iii mk76111039 fluv. – anthrop. alluvia steppe environments at oristano pranu tiria environments and campu forru and lakes in hills pranu tiria references assorgia a., beccaluva l., di paola g.m., maccioni l., macciotta g., puxeddu m., santacroce r. & venturelli g. 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(1979) semiologia del paesaggio italiano longanesi, milano. 273map of the landscape units ... imp.marra& the albano maar (alban hills volcanic district, italy): active or dormant volcano? fabrizio marra1 & daniel b. karner2 1istituto nazionale di geofisica e vulcanologia, sezione di sismologia e tettonofisica, via di vigna murata 605, 00143 roma, italia 2department of geology, sonoma state university, 1801 east cotati avenue, rohnert park, ca 94985, u.s.a. abstract: f. marra, d. b. karner, the albano maar (alban hills volcanic district, italy): active or dormant volcano? (it issn 03943356, 2005). we discuss the geochronological interpretation of several stratigraphic sections where either primary or reworked volcanic products of the most recent eruptive activity of the albano maar are exposed. a recently performed set of 112 singleand multiple-crystal 40ar/39ar age determinations, totalling 244 dated crystals from samples of the albano products, suggests that no magmatic activity occurred after 36 ka. therefore, based on the lack of evidence for eruptive activity in historical time, albano should be defined an inactive volcano. the time elapsed since the last eruption, however, does not overrun the average recurrence time (45 kyr) for the overall volcanic activity of the alban hills volcanic district through the last 600 kyr, indicating that albano should be regarded as a dormant volcano rather than extinct. differently from direct 40ar/39ar dating of the volcanic products, recent c14 age determination on two paleosoils have suggested that eruptive activity younger than 5,000 years occurred at the albano maar. this interpretation contrasts with the absence of any volcanic deposit in the sedimentary fill of the albano crater spanning the time interval 25 ka present, therefore we believe that the possibility that the dated organic material may have been affected by problems of contamination should be carefully considered. indeed, stratigraphic, paleomorphologic and paleoclimatic data that we present in this paper are as well compatible with an early emplacement around 39-36 ka for all of these volcaniclastic products, either primary or reworked. riassunto: f. marra, d. b. karner, il maar di albano (distretto vulcanico dei colli albani, italia): vulcano attivo o quiescente? (it issn 0394-3356, 2005). in questo articolo discutiamo l'interpretazione geocronologica di alcune sezioni stratigrafiche in cui affiorano i prodotti, sia primari che rimaneggiati, della fase più recente di attività del maar di albano. una serie di 81 datazioni effettuate recentemente col metodo 40ar/39ar su singoli e multipli cristalli, per un totale di 244 cristalli datati, suggerisce l'assenza di attività magmatica posteriore a 36 ka. ne segue che, in base all'assenza di evidenza certa di attività eruttiva in tempi storici, albano dovrebbe definirsi un vulcano inattivo. d'altra parte, il tempo trascorso dall'ultima eruzione datata (36 ka) è inferiore al tempo medio di ricorrenza (45 kyr) determinato per l'intera storia eruttiva dei colli albani negli ultimi 600 kyr, indicando che albano deve considerarsi un vulcano quiescente, ma non estinto. diversamente dalle indicazioni radiometriche sui prodotti vulcanici, alcune datazioni effettuate con il metodo c14 su paleosuoli hanno fatto ipotizzare l'esistenza di attività eruttiva del maar di albano posteriore a 5000 anni fa. questa interpretazione appare in contrasto con l'assenza di prodotti vulcanici all'interno dei depositi sedimentari che colmano il fondo del lago di albano e che coprono un intervallo temporale compreso tra circa 25.000 anni fa e il presente, facendoci sospettare che l'attendibilità delle datazioni effettuate col metodo c14 debba essere più attentamente riconsiderata. effettivamente, una serie di dati stratigrafici, paleomorfologici e paleoclimatici che vengono discussi in questo articolo sembrano compatibili con una messa in posto attorno a 39-36 ka per tutti questi prodotti volcanoclastici, sia primari che rimaneggiati, affioranti nelle sezioni descritte. keywords: alban hills, albano maar, geochronology, volcanism, hydromagmatic activity, peperino. parole chiave: colli albani, maar di albano , geocronologia, vulcanismo, attività idromagmatica, peperino. il quaternario italian journal of quaternary sciences 18(2), 2005 173-185 introduction recent studies (villa et al., 1999; karner al., 2001a; funiciello al., 2002; 2003; marra al., 2003; soligo al., 2003; freda al., 2005) have focused on evaluating the stratigraphy and the geochronology of the most recent phase of activity of the alban hills volcanic district and re-evaluating its significance in terms of possible volcanic hazards for rome. however, these works sometimes proposed different stratigraphic interpretations, as well as different time intervals, for this recent volcanic activity. in particular, there is no agreement on the age of the last eruption that occurred in the albano maar, where the youngest volcanic activity occurred. this is a fundamental issue in order to establish if we have to consider the albano maar to be an active or a dormant volcano. indeed, based on the strict definition proposed in the smithsonian institution's catalogue of active volcanoes, only volcanoes that have erupted in the last 10,000 years should be considered active. alternatively, it is considered that a volcano is dormant when the time elapsed since its last eruption does not exceed the average recurrence period of its past activity. establishing which was the actual last eruption that occurred at the albano maar is fundamental to evaluate the recurrence times and the time elapsed since the last eruptive event, therefore it has a relevant implication on the assessment of the potential hazard for the city of rome. recent work (marra al., 2003; 174 f. marra & d.b. karner marra al., 2004) has pointed out that, based on the average recurrence time of the major volcanic cycles that occurred in the last 600 kyr, the alban hills should be considered a dormant volcano. this is based on the observation that the last eruptive cycle documented by 40ar/39ar dating in the alban hills spanned the interval 39±1 ka to 36±1 ka in the albano maar, whereas the average recurrence time through the history of this volcanic district has been estimated to being approximately 45 kyr. here we propose a re-interpretation, based on 40ar/39ar ages of volcaniclastic deposits (freda al., 2005), of the geochronology for some of the most significant sections where the youngest products of the albano activity crop out. in particular we discuss the chronostratigraphy of two sections described in previous works (gra-appia antica and lucrezia romana sections, soligo al., 2003: funiciello al., 2002; 2003), where primary volcanic deposits and post-eruptive lahars and debris-flows were interpreted to be younger than 23±6.7 ka and, in part, younger than 5±0.1 ka. we suggest that the emplacement of the most portions (if not all) of these products more likely occurred in the time span 70 36 ka. we base our interpretation on the 40ar/39ar ages achieved for the primary products cropping out at these sections, while we rely on stratigraphic correlations and paleoclimatic inferences to estimate the ages of the reworked layers. the albano maar the albano multiple-maar center (fig. 1) hosted the most recent activity of the alban hills volcanic district (villa al., 1999; karner al., 2001a; marra al., 2003; soligo al., 2003; funiciello al., 2002; 2003, freda al., 2005). it was described (de rita al., 1995a; 1995b) as a multiple tuff ring, the activity of which consisted of five main explosive cycles. the fifth eruption cycle of albano maar was driven by phreatomagmatic fragmentation and emplaced a phreatomagmatic basic ignimbrite (giordano al., 2002a). this ignimbrite is the most famous deposit of albano, as it was quarried since the iv century b.c. by the ancient roman builders and extensively used under the name of lapis albanus. the dark-grey colour and the granular texture of this rock led to the local name of “peperino” (black pepper-like), and so this unit is known in the literature also as “peperino di marino” or “peperino albano”. the eruptive activity of albano maar was dominated by surge flows which deposits typically show sharp lateral facies variations over relatively short distances. subordinate fall beds are present throughout the succession. the surge deposits commonly show planarto crosslaminations in the proximal area, whereby they have massive, lithified facies in the distal sections, where they fill paleovalleys. the scarcity of outcrops due to the vegetation cover and the large development of agricultural soils prevent the straightforward correlation through different localities, therefore making difficult the stratigraphic correlation among the different units. the petrography and chemistry of the albano products is very homogeneous (trigila al., 1995; marra al., 2003; freda al., 2005), preventing the identification of any characteristic feature that may be distinctive of the different volcanic units. these facts limit the possibility to establish stratigraphic relationships for the different volcanic units, when they do not occur in the same outcrop. a powerful tool to overcome these difficulties is the 40ar/39ar dating of the volcanic products that, based on the high precision and reliability of the method, allows for a certain correlation of primary volcanic products containing juvenile phenocrysts (karner and renne, 1998; karner al., 2001a; marra al., 2003, freda al., 2005). here we discuss the implications on the geochronology of the most recent phase of activity of recently obtained 40ar/39ar data on 12 volcanic deposits of the albano maar (freda al., 2005). these data allow us to correlate two distal sections (gra-appia antica and casale ferranti), where the supposedly youngest products are found, to the best exposed and most complete (found so far) proximal stratigraphic section, located within the crater rim of the albano maar. the correlation of these outcrops is shown in fig. 2. albano lake proximal sections the best exposed section crops out within the northern crater rim (site 1 of fig. 1, reference section of fig. 2) and shows a succession of pyroclastic deposits about 80 m thick. this succession overlies a ~1.5 m-thick mature paleosol, developed on pre-albano hydromagmatic products dated 203±1 ka and attributed to the activity of the nearby ariccia maar (marra et al., 2003). four incipiently pedogenized ash levels indicate the occurrence of four main hiatuses in the albano maar activity, while small-scale unconformities (either erosional surfaces and thin pedogenized ash layers) record less significant hiatuses. the uppermost part of the albano succession does not crop out at the reference section, whereas it is exposed in several outcrops on the eastern and southern outer rims of the albano maar. the most complete of these outcrops is shown in fig. 2 (site 1' in fig. 1). a detailed description of the stratigraphy and of the petrologic features of the products that crop out at these sections is provided in freda et al. (2005). based on 40ar/ 39ar ages, two major eruptive cycles, separated by approximately 30 kyr of dormancy, are recognized at the albano lake sections (fig. 2). the first cycle occurred at 69±1 ka, while the second one was characterized by two distinct eruptive sub-cycles at 39±1 and 36±1 ka (see fig. 2 and fig. 3). the first cycle produced the lower, more than 60 m thick, suite of deposits at the reference section. one faintly pedogenized ash layer occurs in the middle of the lower portion of the succession, suggesting the presence of two separate eruptions with statistically indistinguishable ages of 69.4±0.6 ka and 68.6±1.1 ka, respectively. a thick deposit of ash partially altered into clay and capped by a pedogenized layer closes the stratigraphic succession of the first eruptive cycle. two other incipiently pedogenized ash layers divide the products of the second cycle of activity into at least three different eruptions. these three eruptions occurred at radioisotopically indistinguishable times: the products at the base of the second cycle yielded an age of 41.2±1.1 ka, whereas those at the top yielded an age of 175the albano maar ... fig. 1 geologic map of the alban hills, redrawn from freda et al., 2005. schema geologico dell'artea dei colli albani, ridisegnato da freda et al., 2005. 40.9±0.8 ka. the uppermost deposit that crops out along the eastern and southern crater rim (site 1'), and that is missing on top of the reference section, yielded an age of 35.9±0.6 ka. this is a radiometrically distinct age with respect to the previous ones, and enables us to consider it to be the youngest (dated so far) product of the albano activity and to correlate it to the peperino albano that crops out in valle delle petrare. 176 valle delle petrare sections the peperino albano deposit is more commonly known by its historical name, lapis albanus. one sample of this stone, collected from the walls of an ancient roman monument (the tullianum in the carcere mamertino) was dated by 40ar/39ar methods at 35.7±1.1 ka (karner et al., 2001b). freda et al. (2005) carried out a new dating on a sample of peperino albano deposit collected in the ancient roman quarries located in valle delle petrare. this sample yielded the age 36.1±0.3 ka, in perfect agreement with that previously determined. gra-appia antica distal section 40ar/39ar datings were carried out on three samples (ah18-c1, ah18-c3, ah18-c2, see fig. 2) collected in three different volcaniclastic deposits cropping out at the gra/appia antica section (freda et al., 2005). from the bottom to the top they yielded ages of: 1) sample ah18-c1, 68.9±0.2 ka. this is the age of the first (oldest) eruptive cycle of the albano maar, as previously determined (marra et al., 2003) on the equivalent unit cropping out within the albano fig. 2 stratigraphic scheme showing the relationship among the investigated sections, as inferred from petrographic correlation and 40ar/39ar ages of the collected samples (modified from freda et al., 2005).two major eruptive cycles occurred at albano maar: the first one at 69±1 ka, and the youngest one including two statistically distinct, sub-cycles at 39±1 ka and 36±1 ka. during the youngest eruptive cycle the peperino albano pyroclastic flow was emplaced. schema stratigrafico mostrante le relazioni stratigrafiche esistenti tra le diverse sezioni studiate, basato su correlazioni pertrografiche e sulle età 40ar/39ar dei campioni analizzati (modificato da freda et al., 2005). due principali cicli eruttivi sono riconosciuti per il maar di albano: uno più antico a 69±1 ka, ed uno più giovane, che comprende due sub-cicli con età statisticamente distinte di 39±1 ka e 36±1 ka. durante l'ultimo di questi sub-cicli avviene l'eruzione del peperino albano. crater, and confirmed by the age of another sample (ah3-c9) from the upper portion of the lower succession at the albano lake reference section (see fig. 2). according to funiciello et al. (2003) the product we dated shows the feature of a primary phreatomagmatic pyroclastic-flow deposit, therefore the age of the crystals that we separated from the juvenile portion of the deposit should be considered indicative of the emplacement time. 2) sample ah18-c3, 39.0±0.2 ka. this age falls into the time span encompassed by the second eruptive cycle of the albano maar (fr e d a et al., 2005). according to funiciello et al. (2003) we also interpret this unit to be a primary phreatomagmatic deposit, therefore also in this case the age of the dated crystals is indicative of the emplacement time. 3) age of sample ah18-c2 was obtained by combining 8 age determinations from two samples (ah18-c2 and gra-c2bis, see fig. 3) collected in the same, uppermost volcaniclastic deposit that crops out at the gra/appia antica site. these crystals yielded a combined age of 36.0±0.1 ka. this age is indistinguishable from those obtained on several samples of f. marra & d.b. karner 177 peperino albano dated so far. this uppermost volcaniclastic horizon appears to be reworked, with sorting, massive facies, stratified base and subrounding of the components, indicating a mechanism of emplacement from a hyperconcentrated flood flow (funiciello et al., 2003). the three deposits described above correspond, from lowest to highest, to the volcanic layers to which funiciello et al. (2003) have attributed the following stratigraphic and geochronologic interprertations: 1) peperino albano phreatomagmatic ignimbrite (d layer in their figure 3); 2) phreatomagmatic surge deposit (f layer in their figure 3), “...to be considered the youngest and previously never described phreatomagmatic eruption from the albano maar...”; 3) hyperconcentrated flow sandy deposit (h layer in their figure 3). based on an u/th series age (soligo et al., 2003) on a carbonate layer underlying the volcaniclastic succession at the gra/appia antica site, funiciello et al. (2003) interpreted the entire section to be younger than 23±6.7 ka. moreover, based on a 14c age of 5100±100 years b.p. on an incipiently pedogenized ash layer underlying the youngest volcaniclastic deposit (layer h in their figure 3), they interpreted the uppermost deposit as a lahar deposit originated by the overspill of the albano maar lake in historical time. the geochronologic data and the stratigraphic interpretation by funiciello et al. (2002) and soligo et al. (2003) are in strong conflict with the direct 40ar/39ar datings of these deposits, as we discuss below. casale ferranti distal section this is another location where distal products of the albano maar activity crop out. the deposits fill an ancient paleovalley and they were previously recognized and investigated through a trench excavation (lucrezia romana site, funiciello et al., 2002). we have studied this paleovalley and its volcaniclastic filling in the casale ferranti site, by means of four borecores located in a construction yard adjacent to the lucrezia romana site. we dated and analyzed two samples from these borecores, corresponding to the uppermost and to the lowermost volcanic deposits that fill the paleovalley (fig. 2). the lowest sample (ah19c2) is a well-indurated, massive deposit that yielded a 40ar/39ar age of 38.8±0.2 ka. the age and petrographic features (freda et al., 2005) of this sample match well those of sample ah18-c3 in the gra/appia antica section, and sample ah3-c14 at the albano lake section (site 1 in fig. 1). thus, this is very likely a primary product erupted during the early phase of the second eruptive cycle. the uppermost sample (ah19-c1bis) is an aggregate of rounded scoria, leucite and femic crystals, and heterogeneous lithic fragments. two younger crystals from this sample yielded a combined age of 38.2±0.3 ka. however, the abundance of contaminant crystals (four crystals out of six, see appendix) from the scoria cones activity that ended the villa senni eruptive sequence (351±3 – 356±4 ka, k a r n e r et al ., 2001a), and from the monte delle faete phase of activity (308±4 – 250±1 ka, marra et al., 2003), suggest that this may be a thoroughly reworked product. funiciello et al. (2002) have correlated the stratigraphic section at lucrezia romana to the similar volcaniclastic succession that fills the paleovalley in the gra/appia antica location. the correlation of the two sections is based on a 14cage of 5150±70 yrs bp obtained on a soil underlying a 20 to 50 cm thick “hyperconcentrated flow deposit” that is at the top of a volcaniclastic succession that fills the paleovalley at lucrezia romana (see fig. 5 in funiciello et al., 2002). fig. 3 ideogram (age probability diagram) of the crystal ages from all the dated samples from the albano center, using 2σ analytical error distributions. three prominent peaks are noted: ages from each sample tend to concentrate into one peak of the ideogram, supporting the interpretation of three geochronologically distinct eruptive events. single crystal ages for the samples of the youngest two eruptive events are reported, showing that the crystals which group into the two modes at 36 ka and 39 ka belong to two distinct groups of samples that have always stratigraphic position that is consistent with their radiometric age. ideogramma (diagramma probabilistico delle età) relativo alle età dei cristalli di tutti i campioni di prodotti dell'attività di albano datati, con distribuzione analitica dell'errore a 2σ. si notano tre picchi principali: l'età di ognuno dei campioni si concentra all'interno di un singolo picco dell'ideogramma, indicando l'esistenza di tre eventi geocronologicamente distinti. sono inoltre riportate le età dei singoli cristalli dei campioni che originano i due picchi più recenti, evidenziando che i cristalli che originano le due mode che definiscono due eventi eruttivi a 36 e 39 ka appartengono a due gruppi di campioni che hanno sempre una posizione stratigrafica consistente con l'età radiometrica. the albano maar ... 178 discussion 1. geochronologic and stratigraphic remarks the correlation of the primary deposits units cropping out at the gra/appia antica section with those previously studied at the albano crater by de rita et al. (1988; 1995a; 1995b) and dated by marra et al. (2003) and freda et al. (2005) is straightforward. this correlation is based on the principle of stratigraphic succession (fig. 2), and based on the high quality of the dates performed (see fig. 3 and appendix). from this large set of dated volcanic deposits we obtained ages that have always been stratigraphically consistent and that define statistically distinct eruption ages at 69±1, 39±1, and 36±1 ka. figure 3 shows an ideogram of all the crystals (112 singleand multiple-crystal age determinations involving a total of 244 crystals, see appendix) that we have dated out of 12 different samples of products of the albano activity. the inset in figure 3 shows that the crystals that group into the two modes at 36 and 39 ka belong to two distinct groups of samples that have stratigraphic positions that are consistent with their radiometric ages. therefore, the interpretation of the basal horizon of the gra/appia antica section that led funiciello et al. (2003) to identify it as a deposit of the peperino albano is not supported. indeed, except for radiometric ages of the crystals of the juvenile fraction of the deposit, there is no other macroscopic feature (either in mineralogic composition or in the sedimentologic characteristics) that can distinguish it from other distal products of the several pyroclastic-flow deposits erupted by the albano maar. moreover, the interpretation by funiciello et al. (2003), that the entire succession cropping out at the gra/appia antica section is younger than 23±6.7 ka, is in conflict with the ages obtained on crystals from the juvenile fraction of the exposed deposits. therefore, excluding that the whole volcaniclastic succession is completely reworked, the u/th series age on the carbonate layer at the base of the gra/appia antica volcaniclastic succession (soligo et al., 2003; c layer in their figure 3) should be considered the result of post-depositional process (e.g., recrystallization, significantly later precipitation of carbonate). however, there are no evidences that the succession is entirely reworked. we conclude that the two primary pyroclastic deposits, that with their supply of synand post-eruptive debris-flow deposits represent more than 90% of the entire volcaniclastic succession cropping out at the gra/appia antica site, are distal products of the two main eruptive cycles that occurred at the albano maar 69±1 ka and 39±1 ka. regarding the uppermost deposit above the soil dated 5 ka, we believe that a more thorough geochronologic investigation should be conducted in order to evidence the reliability of this young age. the 14c age of 5100 years was performed on an immature soil that occurs at less than 1 meter below the ground surface (see figure 5 in funiciello et al., 2002): in these conditions the possibility of contamination of the dated material is always possible since the shallow burial does not guarantee sealing and preservation from younger contaminant material. unfortunately, no description of the sampling and dating procedure of the paleosoil is given in funiciello et al. (2003) and in funiciello et al. (2002). funiciello et al. (2002; 2003) have not clarified if they interpret the deposit above this paleosoil to be a primary volcanic layer or a reworked product. based on the homogeneous population of crystals yielding age of 36±1 ka (evidencing lack of xenocrystic contamination) and based on the chronostratigraphic consistent position and on the petrographic characteristics of this deposit, we believe that also the third, uppermost horizon may be regarded as a syn-eruptive deposit (i.e.a syn-eruptive lahar of the peperino albano ignimbrite). therefore, we believe that the possibility that the entire volcaniclastic succession at the gra-appia antica section was deposited in the time span 70-36 ka cannot be excluded. indeed, a later deposition for the uppermost horizon that we dated to 36.0±0.1 ka is questionable based on several lines of evidence. first, the strictly homogeneous population of crystals (see appendix) indicates reworking from a single deposit (i.e. the peperino albano); this may be suitable for pyroclastic flows as well as syn-eruptive lahars, which originate at the expense of a homogeneous source material (i.e. the material from a single eruption), whereby post-eruptive lahars should more commonly embed a large amount of xenocrysts, since they usually originate from slope failures or flood events that involve deposits from different eruptions. moreover, it seems unlikely that the thin (~10 cm) incipiently pedogenized ash layer that separates this upper volcaniclastic horizon from the underlying phreatomagmatic products that yielded the age of 39.0±0.3 ka may be representative of a ~34 kyr-long hiatus in the deposition of the sequence, as it would be if the former is younger than 5 ka. this is more unlikely when one realizes that interpretations by funiciello et al. (2003) require transportation and redeposition of this material without the incorporation of xenocrysts. based on the above mentioned possible unreliability of the 14c age determination and on the absence of crystals of the youngest albano eruptive event in the uppermost unit, we suggest that further geochronological constraints should be provided in order to prove also that any portion of the volcaniclastic succession that fills the paleovalley at lucrezia romana site may be of holocene age. standing on present data, we cannot exclude that the volcaniclastic succession of the lucrezia romana site correlates to the middle stratigraphic unit at the gra/appia antica section, where a primary unit of the ~39 ka eruptive cycle is followed by debris-flow and fluvial deposit that reworked this same unit along with older volcanic units (fig. 2). 2. paleomorphological and paleoclimatic implications we point out here that the assumption of the ciampino plain being the site of catastrophic inundations in recent times due to the repeated overspill of the albano maar lake, as suggested by funiciello et al. (2002; 2003), is not the only possible interpretation of the geomorphologic feature of this area. based on 40ar/39ar data, another explanation could be that he paleo-valleys of the ciampino area were the location of the emplacement of pyroclastic flows since 70 ka, and it is not possible to exclude that they were already completely filled by 36 ka. the less pronounced erosion that occurs throughout the ciampino plain, that f. marra & d.b. karner funiciello et al. (2002: 2003) have cited as the evidence of very recent overfilling of the hydrographic network, can be explained as well as the result of the earlier emplacement of the synand post-eruptive products of albano in the time span 39-36 ka. the eruption of the peperino albano occurred at a time (36 ka) when about 80% of the erosive phase that began since ~120 ka and culminated into the würmian low-stand (~18 ka) had already occurred (bard et al., 1990; bassinot et al., 1994). the ciampino plain is located on the pyroclastic plateau at the foot of the relief of the alban hills, in a position that is significantly influenced by the processes of erosion and aggradation that occur within the main tributary valleys of the tiber river. these tributary valleys synchronously responded to the erosional-depositional processes that occurred in the tiber river valley (ammerman, 2000; karner & marra, 1998). it is clear that the emplacement of a large amount of volcaniclastic material close to the time of maximum lowering of the sea level may interfere with regular sedimentary and erosive processes and, ultimately, this may be the cause of the ciampino plain being unaffected by erosion successively to the emplacement of the peperino albano phreatomagmatic deposits. a reconstruction of the evolution of the paleovalleys in the greater area of rome is shown in figure 4. a regional uplift of ~40 m that occurred in the last 200 ka (karner et al., 2001 c) was the concomitant cause of rejuvenation of the morphological features of the hydrographic network which, at each glacial maximum in the last two marine isotopic stages 7 and 5, was excavated deeper than during the previous ones. in particular, the river incisions were substantially filled as a consequence of the sea-level rise at the peak of stage 7 (a); then, during the regressive phase culminating in the glacial maximum of stage 6, the paleovalleys were re-incised as a consequence of sea-level fall (b); however, the concomitant regional uplift of approximately 20 m in this time span caused the new excavated valleys to be deeper than those originated during previous lowstand. the subsequent sea-level rise associated to high-stand of stage 5 accounted only for partial filling of these sharp paleomorphologies (c). this phenomenon occurred also during the following, last glacial cycle (d'-e'), when other ~20 m of uplift occurred in this area, resulting in the particular feature of the hydrographic network that is characterized by "canyoning" of the holocene alluvial valley, with prominent, steep banks that border the floodplain, as it is visible in the dem image of figure 5. this feature is absent in the ciampino plain, as observed by funiciello et al (2002), as well as in other, limited sectors of the rome area. figure 4 d" shows the situation of the paleovalleys in area of rome 40 kyr ago, just before the second cycle of activity of albano started. differently than in all the other valleys in the area of rome, the incisions in the ciampino area have been filled by the deposits of the albano activity in the time span 39-36 ka (fig. 4 c'''), thus after 80% of the regression associated to the last glacial maximum had occurred (fig. 4 d"). actually, regression started after 125 ka and culminated 19 ka, whereby the peperino albano was erupted 36 ka: thus only (36-19) 17 kyr of new erosion occurred, after that the marked erosive pattern excavated in (125-36) 89 ka was obliterated by emplacement of the pyroclastic flows. retrograde erosion during the remaining 20% of the last glacial maximum was probably not enough to re-establish the morphologic features of the hydrographic network, that were excavated during the previous several erosive phases (fig. 4 c''''). the holocene sea-level rise then caused this faint morphology to be almost completely obliterated, conferring to the ciampino plain its present character (fig. 4 e'). this becomes more apparent when one realizes that a very similar phenomenon occurred toward the southeast of the albano lake, where another flat sector, similar to that near ciampino is present (figure 5). here, the holocene hydrographic network of the rio torto stream near the locality of santa procula is partially filled and obliterated by the pyroclastic flows and lahars of the 39-36 ka activity (giordano et al., 2002b; marra et al., 2003; fig. 2). this similar feature near santa procula calls for a nearly syn-eruptive infilling of the hydrographic network due to directional emission of pyroclastic flows and the related emplacement of lahars, as illustrated in figure 6, rather than being interpreted as due to the overspill of the albano lake, suggesting that the very same thing may have occurred also in the ciampino plain. 3. evidence from the sediments of the albano lake the absence of any holocene eruptive activity at the albano crater can also be inferred after a careful analyses and discussion of the borecore data of the sediments filling albano lake and the nearby nemi lake, provided by the paliclas scientific project (guilizoni and oldfield eds. 1996). the analyses of these four borecores indicate the lack of any volcanic deposit of the albano maar in the time interval 25 ka present day. the albano lake has a maximum depth of 175 m and the morphology of its bottom suggests the existence of three main craters (see fig. 7b): two craters approximately 2 km in diameter which overlap each other along a nw-se direction, and a third crater with a diameter of 0.5 km at the center of the southeastern one. the smallest crater is evidently also the youngest crater, while the northwestern crater is the oldest. we suggest that these three craters correlate to the three main eruptive cycles at 36 ka, 39 ka and 69 ka, respectively. three borecores (re-labeled here 1, 2 and 3, fig. 7) drilled at different water depths on the bottom of the albano lake were analyzed in chondrogianni et al. (1996). in borecore 1, located at higher elevation (30 m water depth), continuous sedimentary deposits of age between 25.11 and 15.78 ka (age calculated based on two calibrated ages of 21.26 ka and 18.39 ka obtained on pollen grains (errors associated with this ages are not reported), chondrogianni et al., 1996) are present above a volcaniclastic substrate, a sample of which was dated by 40ar/39ar methods at 45±3 ka (villa et al., 1999). age of this sample is consistent with that of the products cropping out at the top of the albano reference section (fig. 2) and, more in general, it is consistent at two sigma with the group of ages that constitutes the youngest sub-cycle (39±1 ka) of the second eruptive cycle of the albano maar (freda et al., 2005). in borecore 2, a longer sedimentary record, spanning the interval ~30 ka present was found above the volcaniclastic substrate dated at 26±1 ka (villa et al., 1999). 179the albano maar ... 180 fig. 4 reconstruction of the alternate phases of erosion and deposition, and the effect of regional uplift that influenced the evolution of the hydrographic network in the area of rome in the last 200 kyr. inset on the right upper corner shows the isotopic curve (redrawn from bassinot et al., 1994) for the last three glacial cycles, and the position of the ages of the eruptive cycles of the albano maar with respect the timing of the glacio-eustatic oscillations. ricostruzione degli effetti combinati dell'alterenarsi delle fasi erosive e deposizionali e del sollevamento regionale che hanno influenzato l'evoluzione del retricolo idrografico nell'area romana negli ultimi 200.000 anni. nell'angolo in alto a destra è mostrata la posizione delle età dei cicli eruttivi del maar di albano sulla porzione della curva degli isotopi dell'ossigeno relativa agli ultimi tre cicli glaciali. f. marra & d.b. karner this latter age would be the youngest eruptive product ever dated by 40ar/39ar methods at the alban hills. however, the step-heating experiments as shown in villa et al. (1999) yielded release patterns that are unusual for alban hills leucites, as stated by the same authors, and ultimately did not produce plateaus that meet standard criteria of 50% concordant 39ar release in three contiguous steps (mcdougall and harrison, 1999). additionally, those experiments used small sampling of these pyroclastic layers (1-3 crystals). given the differences in experimental techniques and methodolo181 fig. 5 dem (digital elevation map) of the alban hills and eastern rome. a prominent hydrographic network in this region is the result of approximately 40 m of uplift during the last 250 kyr (karner et al., 2001c), which produced canyon-like valleys with prominent banks over the floodplains. in this framework, several small sectors appear as isolated plateaus: the most prominent of them is the ciampino plain that funiciello et al. (2003) suggested to be the result of catastrophic inundation in historical times, due to the repeated overspill of the albano lake. however, other similar sectors, like that near the santa procula locality, are probably the result of obliteration of the paleovalleys due to emplacement of pyroclastic flows from the albano maar around 39 ka and 36 ka, after most of the erosion linked with the last glacial maximum had already occurred. immagine dem (digital elevation map) dell'area albana e dell'area orientale di roma. i caratteri molto marcati del reticolo idrografico in questa regione sono il risultato del sollevamento di circa 40 metri avvenuto negli ultimi 250,000 anni (karner et al., 2001c), che ha originato delle valli molto incise, con sponde acclivi che bordano le attuali piane fluviali, in un panorama dal rilievo molto poco marcato. in questo contesto, vi sono alcuni piccoli settori che appaiono come dei plateau isolati: il più evidente di questi è la cosiddetta piana di ciampino che funiciello et al. (2003) hanno suggerito essere il risultato di un colmamento dovuto a catastrofiche inondazioni in tempi storici, originate dalla tracimazione del lago di albano. si nota tuttavia che altri settori del tutto simili, come quello qui evidenziato in prossimità della località di santa procula, sono più verosimilmente il risultato dell'obliterazione delle paleovalli ad opera della messa in posto dei flussi piroclastici originati dall'attività del maar di albano intorno a 39 ka e 36 ka, quando gran parte dell'attività erosiva legata all'incipiente massimo glaciale würmiano era già avvenuta. fig. 6 tentative reconstruction of the spatial distribution of the products of the three geochronologically distinct eruptive cycles of albano, based on field survey data and chronostratigraphic investigation. all the eruptions seem to show nw directionality, with the exception of the first subcycle at 39 ka, which according to freda et al. (2005) is the most energetic and emplaced the largest volume of products to the nw as well as to the sw of the albano center. ricostruzione ipotetica della distribuzione spaziale dei prodotti dei tre cicli eruttivi principali del maar di albano, basata su dati di terreno e indagini cronostratigrafiche. tutte le eruzioni sembrano avere direzionalità verso nw, ad eccezione del primo sub-ciclo eruttivo di 39 ka, il quale, in accordo con freda et al. (2005), appare essere il più energetico e ha determinato la messa in posto del maggiore volume di prodotti sia verso nw che in direzione sw rispetto al centro eruttivo di albano. the albano maar ... gies, the error associated to the age of 26 ka obtained by villa et al. (1999) should be considerably expanded when this age is compared to those obtained by freda et al. (2005). therefore, we consider the age of 26±1 ka on the pyroclastic material dated by villa et al. (1999) to be undistinguishable either from the 39±1 ka or 36±1 ka groups of ages obtained for the most recent activity of the albano maar by freda et al. (2005). an age of about 25.44 ka was tentatively calculated (chondrogianni et al., 1996) for the base of the sedimentary deposit recovered in borecore 2, based on the age of 17 ka for one tephra layer recovered in this borecore and correlated to the biancavilla eruption, and assuming a constant sedimentation rate. however, sedimentation rates within a lake can be variable; chondrogianni et al. (1996) estimate the start of the sedimentation of the albano sequences recovered in the analysed borecores to be ~30 ka. if we consider that the deeper portion of the sedimentary fill of the albano lake (at least 50 m, as evidenced by the inferred depth of the lake substrate from seismic reflection data in chondrogianni et al., 1996) was not recovered in the analysed borecores (see fig. 7), it is reasonable to assume that the start of sedimentation may be consistent with a crater formation age of about 36 ka. however, the sedimentary deposit in borecore 2 is not continuous. a hiatus of about 3,000 years is present in between a 14c dated sample at 7.11 ka and an overlying tephra horizon correlated by means of chemical analyses (calanchi et al., 1996) to the avellino eruption which occurred at the somma-vesuvius (santacroce, 1987) and has a calibrated 14c age (stuiver and reimer, 1993) of 4.1 ka. another tephra layer occurs at the middle of borecore 2 and it is correlated (calanchi eet al., 1996) 182 fig. 7 a) cross-section of the sediments of the albano lake, reconstructed using seismic reflection and borecore data (c) in chondrogianni et al. (1996). inset b shows the location of the borecores and of the cross-section. a tentative explanation of the lack of sediments younger than 15.8 ka in core 1 and of the ~3 kyr-long hyatus in core 2 is the lake-level fluctuation as reconstructed in the diagram (d) of this figure, using constrains on the minimum water depth given by the sedimentary record of the three borecores. the absence of any volcanic material within the sedimentary record in the three cores spanning the last 25 kyr that can be attributed to activity of the albano maar clearly suggests that no such volcanic activity occurred. a) sezione stratigrafica dei depositi sedimentari del lago di albano, ricostruita in base a dati di sismica a riflessione e carote di sondaggio (c) da chondrogianni et al. (1996). la pozizione dei sondaggi e della sezione è mostrata nel riquadro b. una possibile spiegazione della mancanza di sedimentazione più recente di 15.8 ka nel sondaggio 1, e della presenza di uno hyatus di circa 3 ky nel sondaggio 2 è verosimilmente costituita dalle oscillazioni del livello del lago, così come sono state ricostruite nel diagramma (d) mostrato in figura per mezzo dei vincoli sulla minima profondità dell'acqua forniti dal record sedimentario. l'assenza di qualsiasi prodotto vulcanico attribuibile all'attività albana all'interno dei sedimenti recuperati dai tre sondaggi, che coprono l'intervallo ~25 ka presente, è una chiara indicazione dell'assenza di tale attività. f. marra & d.b. karner to the y-1 tephra layer (keller et al., 1978) which corresponds to the biancavilla-montalto eruprion, whose calibrated 14c age (stuiver and reimer, 1993) is 17 ka. a continuous sedimentary succession is recovered in borecore 3 which spans the time interval 11.5 ka present and includes the tephra layer correlated to the avellino plinian eruption of 4.1 ka. a similar continuous sedimentary record spanning the time interval 10.78 ka present (chondrogianni et al., 1996) is found at the nearby (~3 km to the sw) nemi lake. in this borecore a tephra layer correlated to the avellino plinian eruption of 4.1 ka (calanchi et al., 1996) is also found interbedded within the sedimentary succession. the sedimentary hiatuses (~15 ka present, ~7 ka~4ka) observed within two of the four described borecores can readily be explained by oscillations of the water level within the albano lake (see figure 7). alternative explanations, as those provided in villa et al. (1999) that the hiatuses may be due to draining of the lake by the opening of new craters, seems implausible since no evidence of these hypothesized eruptive events are found in the borecores drilled at albano lake or nemi lake. the only tephra layers recovered from the sedimentary cores from these lakes during the interval 25 ka present, have chemical composition characterized by high sio2 content (>55% in one case, and >59% in the other three cases) and by low cao content (calanchi et al., 1996), which rules out an alban hills origin. all the volcanic products erupted by this volcanic district since 600 ka have sio2 content below 50% and very high cao content (trigila et al., 1995, marra et al., 2003, freda et al., 2005). it seems quite unlikely that any eruptive activity occurred at the albano maar in the time span 25 ka present, without leaving any trace of volcanic deposits within the sediments of the very same crater lake. conclusions detailed stratigraphic and geochronologic studies conducted recently have chronicled the eruptive history for the albano maar. reworked products of the volcanic activity may have been redeposited as lahars in the last 10,000 years, but it remains to be shown that any magmatic activity has occurred in this time span, based on the lack of any crystal younger than 31±3.6 ka in the entire suite of age analyses that we have determined to be primary volcanic material (244 crystals analyzed in 51 single-crystal and 61 multiple-crystal 40ar/39ar age analyses in freda et al., 2005). based on the geochronologic and stratigraphic data, comprising the lack of any volcanic deposit younger than at least 26 ka correlated to the activity of the albano maar in the sedimentary filling of the crater lake, and based on the analysis of the geomorphological and paleoclimatic context that we have discussed, it seems also reasonable to interpret all the sections that have been suggested to host primary and reworked products deposited in the last 23,000 years (funiciello et al., 2002; 2003), to be instead outcrops of distal, syn-eruptive or short-termed post-eruptive products of the activity that took place at the albano maar in the time span 70-36 ka. the only existing geochronologic constraint that allows to ipothesize an emplacement younger than 36 ka for any product (either primary or reworked) of the albano maar relies on two 14c age age determinations of ~5100 kyr on as many paleosoils. however, we point out that 14c dating of poorly developed, shallow seated soils is always susceptible to be affected by problems of contamination. ages of the crystals within the reworked products that rest above the dated soils, when considered within the larger chronostratigraphic framework that we have outlined, suggest that they may be as well, in one case (gra/appia antica) subcoeval with the peperino albano, and in another case (lucrezia romana-casale ferranti) older than the peperino albano. we conclude that more solid evidences should be provided, comprising both direct and indirect dating, in order to demonstrate that any reworked product among those studied at the graappia antica and lucrezia romana sites has an emplacement age younger than 36 ka. on the other hand, assuming that the 14c age on the two soils provided in funiciello et al. (2002) be reliable, it has to be ascertain if the overlying deposits are primary or reworked products. in the latter case, it would testify to the existence of thin (50 to 100 cm) layers of reworked volcaniclastic material locally accumulated within small fluvial incisions at the foot of the alban hills after the holocene climatic optimum, which would imply a simple sedimentary process, rather than catastrophic inundations. completely different would be the case of the identification of primary volcanic products resting above the soils dated by 14c method at 5 ka. in this case the assessment of the reliability of the 14c age becomes a crucial task to establish when (and where) their eruption occurred. however, we point out that, based on the average recurrence time of 45 kyr for the overall activity at the alban hills, an eruption at 5 ka following one at 36 ka would diminish the potential hazard rather than increase it. for the moment, if we rely on the strict definition that is adopted in the smithsonian institution's catalogue of active volcanoes, we believe that further, more detailed studies have to be conducted in order to demonstrate that the albano maar is an active volcano. for this reason we are presently involved in a dedicated research unit within the 2005-2007 gnv-dpc v3_1colli albani sub-project, aimed to clarify the issues discussed above. references ammerman a.j. , miller j., ramsay s. 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(2001) mediterreanean sea surface radiocarbon reservoir age changes since the last glacial maximum, science, 294, 1917-1920. stuiver m. & reimer p.j. (1993) extended 14c data base and revised calib 3.0 14c age calibration program, radiocarbon, 35, 215-230. trigila r., agosta e., currado c., de benedetti a.a., freda c., gaeta m., palladino d.m., rosa c. (1995) petrology. in: r. trigila (ed.) the volcano of the alban hills. università degli studi di roma "la sapienza" rome, 95-165. villa i.m., calanchi n., dinelli e., lucchini f. (1999) age and evolution of the albano crater lake (roman volcanic province). acta vulcanol., 11, 305-310. 184 ms. ricevuto il 17 maggio 2005 testo definitivo ricevuto il 20 settembre 2005 ms. received: may 17, 2005 final text received: september 20, 2005 f. marra & d.b. karner 185 appendix 40ar/39ar data. the third column indicates the number of crystals dated in each laser-fusion age determination. samples in italics were interpreted to contain xenocrysts and were eliminated to reduce the mswd (mean square weighted deviation) to below 1.5a reasonable statistic for a group of ages from an eruptive event (see freda et al., 2005 for details on the procedure). these italicized data were eliminated from the error-weighted mean calculations for each sample above, and were eliminated from the ideogram in fig. 3. dati radioisotopici 40ar/39ar. la terza colonna indica il numero di cristalli impiegati per ottenere le singole età dalla loro fusione laser. i dati in italico si riferiscono a cristalli o gruppi di cristalli interpretati come contaminanti ed eliminati dal calcolo dell'età al fine di ridurre la deviazione quadratica sotto il valore di 1.5, che si considera un valore statistico adeguato ad identificare un singolo evento eruttivo (si veda freda et al., 2005, per i dettagli di questa procedura). i dati in italico sono stati eliminati dal calcolo della media pesata per ogni età dei campioni e dall'ideogramma in figura 3. lab.no. sample id # of crystals age (ma) ± 1σd samples included in the youngest population 33135-01 ah-4fbis 1 0,0371 0,0013 33135-02 ah-4fbis 1 0,0358 0,0014 33135-03 ah-4fbis 1 0,0329 0,0011 33135-04 ah-4fbis 1 0,0333 0,0011 33135-05 ah-4fbis 1 0,0358 0,0012 33135-06 ah-4fbis 1 0,0355 0,0011 weighted mean (4) 0,0359 0,0006 11375-01 ah18-c2 2 0,0358 0,0002 11375-02 ah18-c2 2 0,0363 0,0003 11375-03 ah18-c2 2 0,0363 0,0003 11375-04 ah18-c2 2 0,0356 0,0004 11375-05 ah18-c2 2 0,0357 0,0003 11383-01 gra-c2bis 2 0,0375 0,0005 11383-02 gra-c2bis 2 0,0367 0,0005 11383-03 gra-c2bis 2 0,2226 0,0009 11383-04 gra-c2bis 2 0,0387 0,0013 11383-05 gra-c2bis 2 0,0398 0,0008 11383-06 gra-c2bis 2 0,0374 0,0004 11383-07 gra-c2bis 2 0,0448 0,0011 weighted mean (8) 0,0360 0,0001 11075-01 mam-01 8 0,0406 0,0040 11075-02 mam-01 8 0,0445 0,0037 11075-03 mam-01 8 0,0334 0,0024 11075-04 mam-01 8 0,0324 0,0025 11075-05 mam-01 8 0,0370 0,0044 11075-06 mam-01 8 0,0345 0,0037 11075-07 mam-01 8 0,0392 0,0031 11075-08 mam-01 8 0,0315 0,0039 weighted mean (8) 0,0357 0,0011 33805-01 ah17-c3 1 0,0463 0,0009 33805-02 ah17-c3 1 0,0372 0,0013 33805-03 ah17-c3 1 0,0325 0,0037 33805-04 ah17-c3 1 0,0354 0,0005 33805-05 ah17-c3 1 0,0390 0,0008 33805-06 ah17-c3 1 0,0376 0,0014 33805-07 ah17-c3 1 0,0352 0,0013 33805-08 ah17-c3 1 0,0380 0,0006 33805-09 ah17-c3 1 0,0372 0,0012 33805-10 ah17-c3 1 0,0384 0,0006 33805-11 ah17-c3 1 0,0348 0,0009 33805-12 ah17-c3 1 0,0483 0,0016 33805-13 ah17-c3 1 0,0362 0,0009 33805-14 ah17-c3 1 0,0410 0,0007 33805-15 ah17-c3 1 0,0343 0,0020 33805-16 ah17-c3 1 0,0512 0,0015 33805-17 ah17-c3 1 0,0373 0,0009 33805-18 ah17-c3 1 0,0398 0,0017 33805-19 ah17-c3 1 0,0368 0,0011 33805-20 ah17-c3 1 0,0420 0,0005 weighted mean (12) 0,0361 0,0003 11391-01 ah19-c1bis 1 0,2986 0,0009 11391-02 ah19-c1bis 1 0,3170 0,0008 11391-03 ah19-c1bis 1 0,3533 0,0011 11391-04 ah19-c1bis 1 0,0390 0,0006 lab.no. sample id # of crystals age (ma) ± 1σd 11391-05 ah19-c1bis 1 0,0381 0,0003 11391-07 ah19-c1bis 1 0,3594 0,0013 weighted mean (2) 0,0382 0,0003 11374-01 ah19-c2 2 0,0402 0,0004 11374-02 ah19-c2 2 0,0380 0,0003 11374-03 ah19-c2 2 0,0397 0,0005 11374-04 ah19-c2 2 0,0405 0,0007 11374-05 ah19-c2 2 0,0402 0,0006 11374-06 ah19-c2 3 0,0390 0,0003 weighted mean (5) 0,0388 0,0002 11376-01 ah18-c3 3 0,0389 0,0007 11376-02 ah18-c3 3 0,0381 0,0005 11376-03 ah18-c3 3 0,0441 0,0003 11376-04 ah18-c3 3 0,0383 0,0005 11376-05 ah18-c3 3 0,0399 0,0005 11376-06 ah18-c3 3 0,0395 0,0005 weighted mean (4) 0,0390 0,0003 33136-01 ah3-c14 1 0,0396 0,0017 33136-02 ah3-c14 2 0,0392 0,0030 33136-03 ah3-c14 5 0,0442 0,0021 33136-04 ah3-c14 3 0,0405 0,0012 33136-05 ah3-c14 4 0,0473 0,0023 33136-06 ah3-c14 3 0,0421 0,0020 weighted mean (5) 0,0409 0,0008 33132-01 ah3-c12l 1 0,0397 0,0040 33132-02 ah3-c12l 1 0,0431 0,0013 33132-03 ah3-c12l 1 0,3571 0,0023 33132-04 ah3-c12l 1 0,0398 0,0016 33132-05 ah3-c12l 1 0,0437 0,0018 33132-06 ah3-c12l 1 0,0498 0,0024 33132-07 ah3-c12l 1 0,0435 0,0010 33132-08 ah3-c12l 1 0,0568 0,0015 weighted mean (3) 0,0412 0,0011 33137-01 ah3-c9 2 0,0679 0,0021 33137-02 ah3-c9 3 0,0686 0,0020 33137-03 ah3-c9 4 0,0719 0,0020 33137-04 ah3-c9 3 0,0534 0,0124 33137-05 ah3-c9 5 0,0689 0,0072 33137-06 ah3-c9 4 0,0629 0,0035 weighted mean (6) 0,0686 0,0011 11385-01 ah18-c1 2 0,0697 0,0009 11385-02 ah18-c1 2 0,0707 0,0006 11385-03 ah18-c1 2 0,0698 0,0004 11385-04 ah18-c1 2 0,0682 0,0005 11385-05 ah18-c1 1 0,0688 0,0004 weighted mean (4) 0,0689 0,0002 11334-01 ah-3a 1 0,0702 0,0012 11334-02 ah-3a 1 0,0690 0,0012 11334-03 ah-3a 1 0,0676 0,0020 11334-04 ah-3a 1 0,0678 0,0017 11334-05 ah-3a 1 0,0721 0,0015 weighted mean (5) 0,0694 0,0006 the albano maar ... imp.capezzuoli-sand. ii sseeddiimmeennttii qquuaatteerrnnaarrii ddeell sseettttoorree mmeerriiddiioonnaallee ddeellllaa vvaallddeellssaa ((pprroovviinncciiaa ddii ssiieennaa)) eennrriiccoo ccaappeezzzzuuoollii && ffaabbiioo ssaannddrreellllii dipartimento di scienze della terra, via laterina 8, 53100, siena. e.mail: capezzuoli@unisi.it; sandrelli@unisi.it riassunto: capezzuoli e. & sandrelli f., i sedimenti quaternari del settore meridionale della valdelsa (provincia di siena). (it issn 0394 – 3356, 2004). gli studi condotti sul settore meridionale della valdelsa (toscana meridionale) hanno permesso di caratterizzare e definire tramite ubsu i locali depositi quaternari. sono stati così riconosciuti sei sintemi (sintema di campiglia dei foci – cdf, sintema dell’abbadia – abb, sintema di calcinaia – cal, sintema del torrente foci – foc, sintema di bellavista – bel, sintema di poggibonsi – pog) che vengono riuniti sotto un unico supersintema indicato come supersintema del fiume elsa. il sintema di campiglia dei foci, composto da quattro litofacies (litofacies argillosa, litofacies sabbiosa, litofacies conglomeratica, litofacies calcarea), viene interpretato come l’espressione di un episodio palustre/lacustre datato al pleistocene inferiore-medio. i sintemi dell’abbadia, di calcinaia, del torrente foci e di bellavista sono riferiti ad una successione di terrazzi tutti caratterizzati da due litofacies (sedimenti calcarei concrezionari e sedimenti detritici) in proporzioni variabili nei vari sintemi e riferiti ad episodi di sedimentazione fluvio-palustre datati al pleistocene superiore-olocene sulla base di una datazione radiometrica. il sintema di poggibonsi corrisponde alle alluvioni attuali ed è formato da sedimenti detritici e localmente da sedimenti calcarei tuttora in formazione. mediante l’integrazione dei dati sedimentologici-stratigrafici con quelli geomorfologici, viene proposta una ricostruzione paleogeografica della valdelsa meridionale dal pleistocene inferiore-medio ad oggi. abstract: capezzuoli e. & sandrelli f., the quaternary sediments of the southern part of valdelsa basin (province of siena). (it issn 0394 – 3356, 2004). stratigraphic and geomorphological researches allow to characterize the quaternary deposits cropping out in the southern part of the valdelsa basin and previously named “ancient travertines” and “recent travertines”. the valdelsa basin is a segment of a nw-se oriented, tectonic depression extending from the serchio valley to the north, to the upper tiber valley to the south. this extensional structure, developed in late miocene, was filled up during pliocene with thick terrigenous marine sediments. afterwards, in the upper middle pliocene, the area, as well as most of southern tuscany, emerged. during quaternary the southern part of the valdelsa basin was characterized by episodic calcareous sedimentation. detailed geological investigations enable us to distinguish six quaternary synthems. campiglia dei foci synthem (cdf) – a palustrine/lacustrine synthem crops out in wide subhorizontal terraces with comparable altitudes (average quote 230 m). it is composed of four lithofacies: clayley lithofacies grey clay and clayey silt (max 10 m thick), locally characterized by thin, plane laminations and carbonaceous plant remains. the fossil content is represented by sporadic freshwater and terrestrial gastropods (parmacella), stems and oogons of charophyte and ostracods. in the san gimignano area, lignite-bearing beds, included in this lithofacies, were mined in the early xxth century, up to the total exhaustion, with fossil remains of mammals of earlymiddle pleistocene or of galerian. this lithofacies can be referred to a palustrine environment. calcareous lithofacies – compact, micritic limestone, locally rather vacuolar or with bioturbation (roots). the stratification is locally enhanced by thin silty-marly beds. it is interpreted as a lacustrine environment with highly concentrated caco3 waters. sandy lithofacies poorly cemented, fine-grained, quartzcarbonate sands in beds or lenticular layers (up to 50 cm thick), with a sometimes abundant silty matrix and locally scattered centimetric pebbles occur. in some outcrops, vegetable remains (grass stems and roots) encased in carbonate crusts are present. this lithofacies can be referred to the marginal part of the lacustrine/palustrine basin. conglomeratic lithofacies – conglomerates and paraconglomerates in variable amounts in the different areas of the basin. they are characterized by a medium size, sandy matrix and a commonly massive fabric, except for local moderate imbrication. this lithofacies is interpreted as alluvial fan deposit of small rivers. abbadia synthem (abb); calcinaia synthem (cal); torrente foci synthem (foc); bellavista synthem (bel) – four fluvial/palustrine synthems developed in four orders of terraces upon the recent alluvial sediments and localized along the flanks of the valleys of elsa river and torrents foci and staggia. the deposits of these syntems are represented by two lithofacies: calcareous deposits (t1) formed by bodies of concretionary phytoclastic-phytohermal calcareous tufas associated with compact micritic limestone and occasionally dark silty clays with organic matter; detritical deposits (t2) composed of mixed, terrigenous-carbonate silty sands and lenticular beds of gravels. the calcareous lithofacies are located in precise segments of the fluvial valleys; their origin is connected to springs with highly concentrated caco3 waters, perhaps hydrothermal. a radiometric c14 dating of 25690±180 yr bp performed on a peat layer inside the calcinaia synthem (cal) implies a probable late pleistocene-holocene age for these four synthems. poggibonsi synthem (pog) – fluvial synthem corresponding to the recent alluvial deposits and composed of sand and silty-sand with gravels. locally calcareous tufa are still in formation. these deposits are referred to the holocene. the collected data show that this sector of the valdelsa basin, during the early-middle pleistocene, was characterized by an episode of continental sedimentation. the initial clastic palustrine deposits (clayey lithofacies) and the following lacustrine carbonates (calcareous lithofacies) were both deposited in a probably tectonic depression. the uplifting of the area induced the rejuvenation of the local hydrographic system which cut deeply the pliocene sediments and caused a relevant inversion of relief. along this new hydrographic pattern, during the late pleistocene-holocene, the interaction of tectonic uplift and climatic changes caused the formation of four terraced orders (palustrine/fluvial synthems) locally characterized by the deposition of calcareous tufas. parole chiave: unità stratigrafiche a limiti inconformi, quaternario, travertini, valdelsa, italia. keywords: ubsu, quaternary, travertine, valdelsa, italy. il quaternario italian journal of quaternary sciences 1177(1), 2004, 33-40 34 e. capezzuoli & f. sandrelli 11.. iinnttrroodduuzziioonnee nell’ambito della cartografia geologica regionale alla scala 1:10.000 è stato effettuato uno studio multidisciplinare sul settore meridionale del bacino della valdelsa; in tale area compresa tra poggibonsi a nord, monteriggioni a sud, san gimignano a ovest e staggia senese ad est, affiorano sedimenti recenti prevalentemente carbonatici conosciuti in letteratura come travertini della valdelsa (merla & bortolotti, 1967). tale studio, che si è avvalso di indagini sedimentologiche, stratigrafiche, geomorfologiche (fotointerpretazione) e geocronologiche, ha permesso la definizione delle formazioni quaternarie affioranti nell’area ed il loro inquadramento mediante unità stratigrafiche a limiti inconformi (ubsu). gli studi stratigrafico-sedimentologici permettono una caratterizzazione di questi depositi ed un loro inquadramento paleoambientale e paleogeografico. 22.. iinnqquuaaddrraammeennttoo ggeeoollooggiiccoo il bacino della valdelsa coincide con un tratto di una lunga depressione tettonica con orientazione nwse che si estende dalla valle del serchio a nord fino alla alta valle del tevere a sud (fig. 1). tale bacino è interessato trasversalmente da due importanti lineamenti tettonici: la linea livorno-sillaro e la linea piombinofaenza. la prima delimita a nord il bacino, mentre la seconda, che lo attraversa all’altezza di poggibonsi, coincide con una forte diminuzione dell’ampiezza del bacino stesso da circa 25 km nella parte settentrionale a circa 15 km in quella meridionale (costantini et al., 1988). lateralmente il bacino della valdelsa è delimitato ad ovest dalla dorsale medio toscana, dove affiora principalmente il calcare cavernoso ed in misura minore verrucano, marmi, ofioliti, diaspri e argille a palombini, e ad est dalla dorsale del chianti con formazioni del dominio ligure esterno di età cretacica superiore-eocenica (formazione di santa fiora, formazione di monte morello). il bacino della valdelsa, individuatosi in regime distensivo nel miocene superiore (bossio et al., 1995b), è stato colmato da potenti spessori di sedimenti terrigeni continentali del miocene superiore a cui seguono sedimenti terrigeni marini del pliocene; questi ultimi, riferibili a due cicli sedimentari, sono formati principalmente da sabbie medio-fini (sabbie di san vivaldo) ed in misura minore da argille siltose (argille azzurre) (capezzuoli & sandrelli, 2003). nella parte alta del pliocene medio l’area emerge come la maggior parte della toscana meridionale (bossio et al., 1995a) e solo nel pleistoceneolocene è documentata una ripresa della sedimentazione con la deposizione di sedimenti continentali ed, in particolare, dei travertini. i primi autori che si sono occupati di questi depositi recenti sono pantanelli (1875) e del zanna (1901) che ne forniscono una prima generica caratterizzazione. successivamente, negli anni ’20-’30, prima trabucco (1920) e poi de castro & pilotti (1933), all’interno di relazioni sui giacimenti lignitiferi della toscana, trattano marginalmente dei travertini valdelsani. il primo studio si deve a merla & bortolotti (1967) che, nell’ambito della redazione del f°113 della carta geologica nazionale alla scala 1:100.000, distinguono, sulla base del loro contenuto in stronzio, i travertini antichi, di origine lacustre ed attribuiti al pleistocene superiore, dai travertini recenti, formati per idrotermalismo e riferiti ad un generico olocene. berzi (1972) attribuisce i travertini antichi al pleistocene inferiore-medio sulla base di una fauna a mammiferi rinvenuta al loro interno, fauna che ambrosetti et al. (1972) collocano nel galeriano. più recentemente fazzuoli et al. (1982) riconoscono cinque diversi ordini di terrazzi con travertini nel bacino idrografico del t. foci, (se di san gimignano). ricerche pedologiche sui suoli e paleontologiche su malacofaune dei travertini antichi sono stati condotti da costantini & carnicelli (1986) e manganelli & giusti (1993). recentemente bossio et al. (2000), nell’ambito di studi condotti nell’area di monteriggioni, hanno studiato i travertini antichi attribuendo loro il nome di calcari di pian del casone. 33.. ssttrraattiiggrraaffiiaa ddeeii ddeeppoossiittii qquuaatteerrnnaarrii ddeellll’’aallttaa vvaallddeellssaa lo studio di fotointerpretazione e la distribuzione dei sedimenti quaternari dell’alta valdelsa, unitamente ai loro caratteri stratigrafico-sedimentologici, hanno permesso il riconoscimento di sei sintemi i cui rapporti sono indicati in fig. 2: un sintema lacustre-palustre (sintema di campiglia dei foci – cdf), quattro fluvio-palustri (sintema dell’abbadia – abb; sintema di calcinaia cal; sintema del torrente foci – foc; sintema di bellavista – bel) ed uno fluviale (sintema di poggibonsi – pog). questi sei sintemi vengono riuniti sotto un unico supersintema definito supersintema del fiume elsa (els). 33..11.. iill ssiinntteemmaa llaaccuussttrree--ppaalluussttrree:: ssiinntteemmaa ddii ccaammppiigglliiaa ddeeii ffooccii ((ffddcc)) si tratta di depositi localizzati principalmente in due placche suborizzontali (area di campiglia dei foci ed area compresa fra colle val d’elsa e staggia) ed altre di dimensioni inferiori, distribuiti a quote comprese tra 240 m (area di campiglia dei foci) e 230 m s.l.m. (area di pian del casone); nelle aree occidentali a ridosso della dorsale medio toscana le quote di affioramento, probabilmente per motivi tettonici, risultano superiori (quota massima 300 m s.l.m.). tali depositi giacciono di norma su sabbie marine plioceniche o direttamente sul substrato preneogenico; i contatti di base sono rispettivamente di tipo disconformity e angular unconformity, mentre a tetto si rinvengono suoli intensamente rubefatti (costantini & carnicelli, 1986). in alcune aree, alla sommità dei rilievi pliocenici, si osservano superfici relitte pseudorizzontali correlabili con la base dei depositi del sintema. la prevalente natura calcarea dei depositi del sintema (litofacies calcarea), meno erodibile dei sedimenti terrigeni pliocenici, ha provocato una erosione selettiva e determinato in quest’area una inversione del rilievo (bartolini & peccerillo, 2002). il sintema di campiglia dei foci presenta spessori variabili, che diminuiscono rapidamente verso nord; le potenze massime sono dell’ordine di 30 m. tale sintema è caratterizzato da quattro litofacies (fig. 2): litofacies argillosa (litofacies a): consiste di argille ed argille siltose grigie, a luoghi con una sottile laminazio35i sedimenti quaternari ... f ig . 1 s ch e m a g e o lo g ic o d e l s e tt o re m e ri d io n a le d e lla v a ld e ls a . t 1 s e d im e n ti ca lc a re i; t2 s e d im e n ti d e tr iti ci ; a li to fa ci e s a rg ill o sa ; cg li to fa ci e s co n g lo m e ra tic a ; s lit o fa ci e s sa b b io sa ; cl lit o fa ci e s ca lc a re a . l e li to fa ci e s d e l s in te m a c d f e i d e p o si ti d e i s in te m i a b b , c a l ,f o c e b e l , a q u e st a s ca la , n o n s o n o e vi d e n zi a b ili s in g o la rm e n te . g e o lo g ic a l sc h e m e o f th e s o u th e rn v a ld e ls a b a si n . t1 c a lc a re o u s se d im e n ts ; t2 d e tr iti ca l se d im e n ts ; a c la yl e y lit h o fa ci e s ; cg c o n g lo m e ra tic l ith o fa ci e s; s s a n d y lit h o fa ci e s; c l ca lc a re o u s lit h o fa ci e s. t h e li th o fa ci e s o f th e c d f s yn th e m a n d t h e d e p o si ts o f th e a b b , c a l , f o c , b e l s yn th e m s a re n o t se p a ra te ly v is ib le a t th is s ca le . s in te m a d i c a m p ig lia d e i f o ci ( c d f ) cl s a cg _ _ _ f ir e n z e p is a d or sa le me dio m . a lb an o i s o la d 'e lb a g r o s s e t o ra pol ano m on ti pr at om ag no s ie n a del l' a mia ta si c hi an ti cet ona do rsa le a re e e m e rs e p ri n c ip a li d e p re s s io n i te tt o n ic h e in te re s s a te d a b a c in i m a ri n i e c o n ti n e n ta li n e o g e n ic i f a g lie f a g lie d i tr a s fe ri m e n to mo nte vo r a c h ve c a de l d or . v e -c a -s i -b a c in o d e ll a v a ld e ls a -c a s in o -s ie n a to s c a n a a re a s tu d ia ta pf ls l s l in e a l iv o rn o -s ill a ro p f l in e a p io m b in o -f a e n z a 2 5 k m 0 v o -r a -c h b a c in o d i v o lt e rr a -r a d ic o n d o li -c h iu s d in o p o g g ib o n si c o lle v a l d 'e ls a s a n g im ig n a n o s ta g g ia g ra cc ia n o m o n te ri g g io n i c a st e lli n a s ca lo c a m p ig lia d e i f o ci f. els a s in te m a d e ll' a b b a d ia ( a b b ) s in te m a d i c a lc in a ia ( c a l ) s in te m a d e l t .f o ci ( f o c ) s in te m a d i b e lla vi st a ( b e l ) t2 t1 s in te m a d i p o g g ib o n si ( p o g ) f. elsa f. elsa 1 k m u n ità l ig u ri e t o sc a n a p re n e o g e n ic h e s e d im e n ti m a ri n i p lio ce n ic i s e d im e n ti co n tin e n ta li m io ce n ic i t. s ta gg ia t. f o ci t. foci b . i m bo tro ni t. s ta gg ia 36 ne, caratterizzate da estensione variabile e spessore massimo di circa 10 m. lateralmente questa litofacies è eteropica con le sabbie e i conglomerati delle litofacies (cg) e (s) (si veda fig. 2), mentre al tetto è spesso visibile un passaggio graduale alla litofacies calcarea (cl). la sommità delle argille è caratterizzata da un livello pedogenizzato osservabile in due tagli artificiali. il contenuto paleontologico è caratterizzato da frustoli carboniosi, scarsi ostracodi e gasteropodi dulcicoli (lymnea stagnalis l., paludina contecta müll. e planorbis marginatus drap.) e terricoli (parmacella sp.1 sensu manganelli & giusti, 1993). nella zona a sud di san gimignano è stata inoltre segnalata l’esistenza di lenti di lignite, oggetto di coltivazione ai primi del ‘900 fino al totale esaurimento (trabucco, 1920; de castro & pilotti, 1933). queste lenti hanno fornito una fauna a mammiferi (equus caballus l., cervus elaphus l., bos primigenius boj., hippopotamus major cuv., elephas antiquus falc.) e molluschi attribuiti da berzi (1972) al pleistocene inferioremedio. successivamente ambrosetti et al. (1972), in un quadro classificativo più ampio dei depositi pleistocenici dell’italia centrale, hanno riferito questa stessa fauna al galeriano. questa litofacies argillosa viene attribuita ad un ambiente di tipo palustre. litofacies sabbiosa (litofacies s): consiste di sabbie fini calcaree con una frazione detritica silicea più o meno abbondante, ocracee e con occasionali nuvole o lenti di ciottoli centimetrici a basso grado di cementazione. i fossili presenti sono scarsi e rappresentati esclusivamente da resti vegetali incrostati (fitoclasti). le sabbie hanno una stratificazione pianoparallela non sempre evidente con spessori massimi di 50 cm. questa litofacies, che mostra rapporti di eteropia con tutte le altre litofacies (a) (cl) (cg), è riferibile ad aree marginali di lago/palude, nelle quali si avevano probabilmente spiagge legate a piccoli immissari. litofacies conglomeratica (litofacies cg sinonimo dei conglomerati di poggibonsi di merla & bortolotti, 1967): si tratta di conglomerati e paraconglomerati la cui composizione degli elementi varia passando dal settore orientale, dove si hanno soprattutto calcari e calcari marnosi, a quella occidentale a ridosso della dorsale medio toscana dove sono si hanno elementi derivati dal calcare cavernoso, “palombini”, diaspri ed ofioliti. il conglomerato solitamente si presenta massivo ed eccezionalmente si osservano clasti embriciati; la matrice, a luoghi predominante, è sabbiosa. la litofacies cg è interpretabile come l’espressione di piccoli delta posti prevalentemente sui lati occidentale ed orientale del lago/palude. litofacies calcarea (litofacies cl): è rappresentata da un calcare micritico, a grana fine o medio-fine, di colore bianco sporco con sfumature nocciola e/o rosa. la stratificazione è spesso ben visibile ed è messa in evidenza da sottili livelli siltoso-marnosi (max 15 cm nell’area di campiglia dei foci) interposti ai banchi calcarei spessi da 40 cm a circa un metro. a luoghi il calcare micritico è vacuolare, con evidenti bioturbazioni provocate da apparati radicali, oppure è associato a piccole lenti con strutture fitoclastiche. il contenuto paleontologico è sempre scarso; occasionalmente si ritrovano impronte interne di gasteropodi, mentre in sezione sottile si osservano ostracodi, steli ed oogoni di characee. il calcare giace generalmente sulle altre litofacies (a), (s), (cg) del sintema di campiglia dei foci, o, in misura minore, direttamente sui sedimenti pre-quaternari, anche se talvolta mostra rapporti di eteropia con le litofacies (s) e (cg). la litofacies (cl) viene interpretata come una deposizione per decantazione, al disotto del livello di base d’onda, nelle zone più profonde di un lago caratterizzato da acque ricche in carbonato di calcio. i rapporti tra le litofacies del sintema di campiglia dei foci (fig. 2) evidenziano un passaggio, verso l’alto, dalla litofacies argillosa a quella calcarea; questa transizione viene interpretata come una evoluzione da un ambiente palustre, con scarse profondità e sedimentazione prevalentemente terrigena, ad uno lacustre caratterizzato dalla sedimentazione di fanghi calcarei nelle aree centrali (litofacies cl) e la deposizione di materiali più grossolani nelle aree marginali, specialmente nelle vicinanze di piccoli immissari (litofacies s, cg). la variazione di sedimentazione da argillosa a calcarea è legata all’apporto di notevoli quantità di acque ad alto contenuto di caco3, verosimilmente collegata fig. 2 ricostruzione stratigrafica dei sei sintemi quaternari riconosciuti nel settore meridionale della valdelsa (non in scala). stratigraphic relationships of the six quaternary synthems recognized in the southern valdelsa basin (not in scale). e. capezzuoli & f. sandrelli 37 ad una accentuata attività tettonica inserita nell’ambito del generale sollevamento che ha interessato l’intera toscana meridionale dal pliocene medio ad oggi (bossio et al., 1995a). la deposizione del calcare, legata alla saturazione della acque, era favorita probabilmente sia da condizioni di endoreicità del bacino (vedi capitolo 4) che ne permetteva la progressiva concentrazione, sia da condizioni climatiche calde, come documentato dal ritrovamento di parmacella (manganelli & giusti, 1993), che accentuava l’evaporazione delle acque. 33..22.. ii ssiinntteemmii fflluuvviioo--ppaalluussttrrii:: ssiinntteemmaa ddeellll’’aabbbbaaddiiaa ((aabbbb)),, ssiinntteemmaa ddii ccaallcciinnaaiiaa ((ccaall)),, ssiinntteemmaa ddeeii ffooccii ((ffoocc)),, ssiinntteemmaa ddii bbeellllaavviissttaa ((bbeell)) questi sintemi sono riferibili ad una successione di terrazzi presenti sui versanti dei principali corsi fluviali dell’area e formati da depositi detritici prevalentemente di tipo terrigeno (sabbie, silt e ciottolami), che in particolari tratti vallivi (lungo il t.foci ad est di campiglia dei foci, lungo il botro degli imbotroni da pod. polveraria fino alla confluenza con il t.foci, lungo il f.elsa dall’abitato di gracciano fino a poggibonsi e lungo il t.staggia da castellina scalo fino a poggibonsi; fig. 1) sono caratterizzati da litofacies calcaree (travertini recenti di merla & bortolotti, 1967). i depositi dei vari sintemi presentano estensioni variabili e spessori fino a circa 20 m. fra i diversi ordini di terrazzo, soprattutto nell’area di poggibonsi, affiorano le sabbie marine plioceniche (terrazzi a ripiani), anche se non mancano casi di terrazzi incastrati specialmente nella zona di colle val d’elsa-staggia e fra il sintema di bellavista ed il sottostante sintema di poggibonsi. tutti i sintemi sono caratterizzati da contatti basali erosivi (disconformity) e da una superficie superiore suborizzontale sulla quale si sono sviluppati suoli rubefatti o bruni. le unità più alte risultano in gran parte smantellate dall’erosione, ma restano documentate da numerose superfici relitte senza depositi. i sedimenti sono riconducibili a due litofacies che presentano gli stessi caratteri nei vari sintemi. litologicamente i depositi calcarei (litofacies t1 in fig. 1) si presentano come alternanze di calcare concrezionario fitoclastico e fitoermale incrostato su corpi vegetali (cannucce, arbusti e fili d’erba) e livelli detritici granulari (calcrete, sabbie calcaree) disposti in livelli e lenti di spessori variabili a seconda delle località. a luoghi si rinvengono caratteristici mound di cannucce (fitoermale) dovuti alla crescita degli organismi vegetali su piccoli rialzi del fondo. in associazione a questi litotipi si hanno livelli lenticolari di calcari micritici, calcari laminari cristallini ed occasionali livelli argillitici torbosi. tali caratteristiche permettono di classificare questi depositi come calcareous tufa di tipo “paludal model” o “fluviatile model” sensu pedley (1990) e pedley et al. (2003). i depositi detritici (litofacies t2 in fig. 1) sono solitamente composti da sabbie calcaree e terrigene e silt di norma malstratificati con associati ciottoli che, a seconda del luogo, possono essere presenti in lenti o livelli. le sabbie calcaree derivano dalla disgregazione, in regime turbolento, delle litofacies calcaree, mentre quelle terrigene dalle sabbie marine plioceniche; entrambe mostrano a luoghi banchi con sequenze di tipo fining-upward. i livelli a ciottoli sono presenti principalmente nella parte basale dei vari sintemi dove costituiscono il riempimento di tasche erosionali. sono composti da clasti eterogenei ben arrotondati di varie dimensioni (max 20 cm), che mostrano solo a luoghi una evidente embriciatura cui si accompagna una matrice sabbiosa variabile. lo scarso contenuto paleontologico di entrambe le litofacies è rappresentato da impronte di foglie di quercus ilex l. e populus laecophylla ung. (del zanna, 1901) e da ostracodi con carapace liscio e sottile, oogoni di carofite e calchi di gasteropodi dulcicoli. i sedimenti di questi sintemi sono attribuiti da merla & bortolotti (1967) all’olocene; recenti studi permettono un riferimento anche al pleistocene superiore, poiché una datazione radiometrica c14 su livello argilloso organico del sintema di calcinaia ha fornito un’età radiometrica di 25.690±180 b.p. (capezzuoli & sandrelli, 2003). sintema dell’abbadia (abb): è il più antico fra i fluviopalustri e corrisponde al terrazzo più alto, con una quota media di 30 m sull’attuale fondovalle. nell’area di l’abbadia (est di colle val d’elsa), il sintema è particolarmente sviluppato sia in estensione laterale sia come spessore (circa 18 m). in generale l’unità è ben conservata nelle aree di affioramento dei calcareous tufa, mentre si hanno solo deboli tracce in quelli di deposizione esclusivamente detritica e/o terrigena. sintema di calcinaia (cal): anch’esso è caratterizzato da calcareous tufa e depositi detritici e corrisponde ai terrazzi posti ad una altezza media di 25 m. recenti lavori stradali nell’area di calcinaia (sud di poggibonsi) hanno evidenziato la presenza di un livello argilloso organico nella parte basale della sezione che ha fornito una datazione radiometrica di 25690±180 b.p.. sintema dei foci (foc): corrisponde ai depositi terrazzati presenti a quote medie di circa 15 m sul fondovalle. buoni esempi si hanno lungo il torrente foci (fig. 3) dove è anche possibile apprezzare una diminuzione nell’estensione dei depositi carbonatici rispetto a quelli presenti nei sintemi fluvio-palustri più antichi. sintema di bellavista (bel): a questo sintema appartengono i depositi terrazzati più recenti posti ad una quota di circa 8 m. anche qui continua il trend di diminuzione dei depositi carbonatici già notato nel sintema dei foci che sono sempre meno presenti in estensione lungo le valli. l’origine dei sintemi fluvio-palustri è probabilmente da riferire sia all’attività tettonica che ha accompagnato il sollevamento neogenico-quaternario della toscana meridionale, sia a variazioni climatiche. infatti alla prima sono da ricollegare la progressiva incisione delle valli fluviali e l’apporto di acque carbonatiche responsabili della sedimentazione dei calcareous tufa, mentre alle seconde vanno imputati i successivi episodi di sovralluvionamento e precipitazione dei calcareous tufa intervallati da fasi erosionali. questa precipitazione si realizzava solo in corrispondenza di alcuni tratti fluviali nei quali erano localizzate le sorgenti, probabilmente idrotermali, associate a faglie, responsabili degli apporti carbonatici. la relazione di questi depositi calcarei con faglie presenti nell’area era già stata ipotizzata da merla & bortolotti (1967), a causa dell’elevato contenuto in stronzio dei travertini recenti della valle del t. staggia, e da costantini et al. (1980). le sorgenti fornivano le i sedimenti quaternari ... 38 acque ad alto contenuto di caco3 che innescavano il processo d’incrostazione lungo il corso d’acqua, dove i sedimenti carbonatici si interdigitavano con quelli terrigeni e detritici dando luogo a frequenti eteropie di facies. lo studio dei depositi permette di individuare una variabilità degli ambienti deposizionali con passaggi da aree caratterizzate da ristagno delle acque (piccoli sbarramenti e stagni isolati con facies fitoermali o argille anche organiche) a zone di deflusso (aree di canale con accumuli fitoclastici, terrigeni o detritici). procedendo verso valle si aveva una progressiva diluizione delle acque calcaree, fino all’esaurimento della capacità incrostante ed alla deposizione solamente di depositi detritici. il minor sviluppo dei sedimenti carbonatici dai sintemi più antichi (sintema dell’abbadia) a quelli recenti (sintema di bellavista) indica, inoltre, una progressiva diminuzione degli apporti di acque carbonatiche che potrebbe essere messa in relazione ad una diminuzione dell’attività tettonica con l’occlusione delle vie di risalita. 33..33.. iill ssiinntteemmaa fflluuvviiaallee:: ssiinntteemmaa ddii ppooggggiibboonnssii ((ppoogg)) corrisponde alle alluvioni recenti, talvolta ben sviluppate nei fondovalle dei vari corsi d’acqua dell’area. sono formate essenzialmente da sabbie e silt sabbiosi con associati ciottoli o lenti di ghiaie. solo a colle val d’elsa (lungo il corso dell’elsa), localmente lungo il torrente staggia (a staggia senese) e in due località nei dintorni di san gimignano (nelle vicinanze di una sorgente idrotermale di esigua portata) sono tuttora in formazione i calcareous tufa. l’età di questo sintema è riferita all’olocene. 44.. iinntteerrpprreettaazziioonnee ppaalleeooggeeooggrraaffiiccaa eedd eevvoolluuzziioonnee ddeell sseettttoorree mmeerriiddiioonnaallee ddeellllaa vvaallddeellssaa nneell pplleeiissttoocceennee iinnffeerriioorree--mmeeddiioo - oolloocceennee con il generalizzato sollevamento della toscana meridionale iniziato nel pliocene medio, vaste aree a sedimentazione marina furono portate in emersione. l’assenza, nella parte meridionale della valdelsa, di depositi compresi fra il pliocene medio ed il pleistocene inferiore-medio, permette di ipotizzare che in tale intervallo l’elevato sollevamento di quest’area abbia dato luogo essenzialmente a processi erosionali legati all’instaurazione di un primo reticolo fluviale (paleo-elsa) probabilmente con andamento nw-se non dissimile dall’attuale. nel pleistocene inferiore-medio sono attualmente documentati i primi depositi continentali dell’area, rappresentati dai sedimenti prima palustri e successivamente lacustri del sintema di campiglia dei foci. una lettura della carta geologica e del reticolo idrografico della porzione meridionale della valdelsa permette una serie di ipotesi sulla paleogeografia dell’area in questa epoca. infatti la posizione degli affioramenti della litofacies calcarea (cl) consente la definizione dell’estensione minima del bacino durante lo stadio lacustre (fig. 4). lo studio dell’attuale reticolo idrografico fornisce ulteriori indizi sull’evoluzione di quest’area. in particolare in riva sinistra del f. elsa si osservano (fig. 4) vari corsi d’acqua tra loro paralleli con percorso in parte rettilineo e orientato in direzione appenninica, ma con verso di scorrimento opposto al f. elsa. al contrario, gli affluenti in riva destra possiedono un andamento circa antiapfig. 4 schema del reticolo idrografico principale del settore meridionale della valdelsa. hydrographic pattern of the southern valdelsa basin. fig. 3 visione da nord della valle del torrente foci ad est di campiglia dei foci. nello schema superiore sono evidenziati i depositi e le superfici relitte dei vari sintemi visibili. view of the torrente foci valley, east of campiglia dei foci. in the upper scheme the deposits and the older surfaces of the quaternary synthems are showed. foc abb cal abb pog cdf cdfcdf foc abb b.ro di vergaia b.ro degli im botroni t. rig ua rdi t. fo ci b.r o d el co nio t. fo ci t. f oc i t. s taggia f. e lsa f. e lsa f. e lsa b.ro delle ferribbie poggibonsi colle val d'elsa certaldo staggia san gimignano t. d ro ve vico d'elsa ulignano linea piombino-faenza soglia ulignano-vico d'elsa cattura fluviale limite alluvioni recenti verso di scorrimento possibile limite paleolago 1 km e. capezzuoli & f. sandrelli penninico, ma anch’essi con una direzione preferenziale opposta al deflusso del f.elsa e quindi diretta verso le aree meridionali. questa peculiarità idrografica è presente fino all’altezza degli abitati di vico d’elsa ed ulignano, oltre i quale gli affluenti sia di destra che di sinistra assumono tracciati e deflussi verso i settori settentrionali. si viene così ad individuare, in corrispondenza di queste due località, un’area a sviluppo antiappenninico trasversale alla valdelsa che di fatto delimita verso nord il bacino lacustre. la conferma di una probabile soglia è avvalorata dal fatto che, coincidente con questa fascia trasversale, si ha una forte diminuzione nell’estensione laterale delle alluvioni recenti (sintema di poggibonsi) ben sviluppate sia a nord sia a sud. una possibile evoluzione di quest’area prevede un iniziale bacino di tipo endoreico formatosi per lo sbarramento del paleo-elsa in corrispondenza dell’area di ulignanovico d’elsa ed il conseguente adattamento dei corsi fluviali a defluire verso i settori meridionali. le cause della formazione di questa soglia, parallela e non molto distante da una importante linea tettonica (linea piombino-faenza; costantini et al., 1980) è da riferire a movimenti tettonici, anche se preliminari rilevamenti geologici svolti in quell’area, caratterizzata da una forte omogeneità dei sedimenti pliocenici, non hanno evidenziato la presenza in superficie di faglie. probabilmente gli stessi movimenti tettonici innescarono anche gli apporti di acque carbonatiche che variarono la sedimentazione del bacino da palustre/terrigena a lacustre/carbonatica. successivamente una probabile erosione regressiva del tratto settentrionale del paleo-elsa incise tale soglia determinando lo svuotamento del bacino lacustre (non sono presenti facies di regressione dei depositi lacustri). conseguentemente anche gli immissari del paleolago, pur mantenendo parziali tratti con l’originale pattern centripeto verso le aree lacustri, avrebbero subìto la cattura da parte di altri corsi d’acqua, variando così il proprio percorso (fig. 4). questa nuova idrografia, impostatasi dopo l’apertura del bacino, ha subìto fino ad oggi un progressivo approfondimento, attuatosi sia per il continuo sollevamento tettonico, sia a causa di variazioni climatiche. in gran parte dell’area si è quindi avuto un’inversione del rilievo con i sedimenti del paleolago, molto competenti, rimasti spesso inalterati in posizione rilevata. l’approfondimento, realizzatosi con meccanismi di sovraimposizione a scapito delle sabbie marine plioceniche, è avvenuto lungo il nuovo pattern idrografico che si era impostato sulla base delle mutate condizioni paleogeografiche (tratti sinuosi incassati del f. elsa fra colle val d’elsa e poggibonsi e del t. staggia fra staggia senese e poggibonsi che documenterebbero estesi ambienti alluvionali successivi al paleolago) e tettoniche (tratti rettilinei del f. elsa a colle val d’elsa in corrispondenza di faglie). negli interstadi delle fasi di approfondimento fluviale si aveva la deposizione di sedimenti terrazzati che in alcuni tratti erano di tipo calcareo (calcareous tufa) grazie ad acque idrotermali carbonatiche risalite lungo alcune faglie. la formazione dei calcareous tufa è diminuita nel tempo, come testimoniato dalla minore presenza di sedimenti calcarei nei sintemi più recenti (sintema del t. foci, sintema di bellavista), fino ad arrivare ai depositi attuali (sintema di poggibonsi) dove le acque del f. elsa formano calcareous tufa solo in poche località. la progressiva diminuzione dei depositi “travertinosi” nel tardo olocene è un fenomeno generalizzato sia in italia che in molti siti dell’europa centro occidentale e riconducibile a cause di tipo climatico o antropico (goudie et al., 1993; dramis et al., 1999). tuttavia in valdelsa potrebbe essere legata ad una risposta più locale e riferita ad una diminuzione dell’attività tettonica conseguente ad un possibile progressivo arresto del sollevamento post-pliocene medio. rriinnggrraazziiaammeennttii gli autori ringraziano la prof.ssa a. gandin per la collaborazione nello studio sedimentologico delle facies carbonatiche. lavoro finanziato con fondi p.a.r. 2001 dell’ università degli studi di siena (responsabile prof. f. sandrelli). llaavvoorrii cciittaattii ambrosetti p., azzaroli p., bonadonna f.p. & follieri m. (1972) – a scheme of pleistocene chronology for the tyrrhenian side of central italy. boll. soc. geol. it., 9911, 169-184. bartolini c. & peccerillo a. (2002) – i fattori geologici delle forme del rilievo. lezioni di geomorfologia strutturale. pitagora editrice, bologna, 216 pp. berzi a. (1972) an early middle pleistocene fauna at monte oliveto (s. gimignano, siena, italy). paleont. it. , 6688, 29-33. bossio a., costantini a., foresi l.m., lazzarotto a., mazzanti r., liotta d., mazzei r., salvatorini g. & sandrelli f. (1995a) – studi preliminari sul sollevamento della toscana meridionale dopo il pliocene medio. studi geol. camerti, volume speciale, 1995/1, 87-91. bossio a., foresi l.m., mazzei r., salvatorini g. & sandrelli f. (1995b) evoluzione tettonico-sedimentaria neogenica lungo una trasversale ai bacini di volterra e della val d’elsa. studi geol. camerti, volume speciale, 1995/1, 93-104. bossio a., mazzei r., salvatorini g. & sandrelli f. (2000) – geologia dell’area compresa tra siena, poggibonsi e castellina in chianti (prov. di siena). atti soc. tosc. sc. nat. mem. serie a, 110077, 69-85. capezzuoli e. & sandrelli f. (2003) – inquadramento geologico della porzione meridionale del bacino della valdelsa. guida all’escursione “l’agricoltura che produce paesaggio”; convegno nazionale “qualità del suolo, impatto antropico e qualità dei prodotti agricoli.”, pag. 78-80, siena, 912/06/2003 costantini a., gandin a., guasparri g., lazzarotto a., mazzanti r. & sandrelli f. (1980) – neotettonica dei fogli: 111 livorno – 112 volterra – 113 castelfiorentino – 119 massa marittima – 120 siena – 121 montepulciano – 126 isola d’elba – 127 piombino – 128 grosseto – 129 s.fiora. in: contributi alla realizzazione della carta neotettonica d’italia. pubbl. p.f.g., 1075-1186. costantini a., lazzarotto a. & sandrelli f. (1988) sulle risorse geotermiche a medio-bassa temperatura 39i sedimenti quaternari ... nella parte meridionale del bacino neoautoctono della val d’elsa. studi preliminari: lineamenti geologici. p.f.e. s.e.g., si-5, 489-514. costantini e.a.c. & carnicelli s. (1986) – forme e suoli della superficie strutturale calcarea di campiglia dei foci (siena). annali ist. sper. dif. suolo, 1177, 68-87. de castro c. & pilotti c. (1933) – i giacimenti di lignite della toscana. mem. descr. carta geol. d’it., 2233, 95-103. del zanna p. (1901) – i travertini di colle e le incrostazioni attuali dell’elsa. boll. soc. geol. it., 2200, 2034. dramis f., materazzi m. & cilla g. (1999) – influence of climatic changes on freshwater travertine deposition: a new hypothesis. phys. chem. earth (a), 2244(10), 893-897. fazzuoli m., garzonio c.a., rodolfi g. & vannocci p. (1982) lineamenti geologici e geomorfologici dei dintorni di san gimignano. ist. sper. stud. dif. suolo, firenze, 1133, 169-203. goudie a.s., viles h.a. & pentecost a. (1993) – the late-holocene tufa decline in europe. the holocene, 33(2), 181-186. manganelli g. & giusti f. (1993) – notulae malacologicae, xlv. fossil parmacellidae from italy. arch. molluskenkunde, 112211, 143-156. merla g. & bortolotti v. (1967) – note illustrative della carta geologica d’italia alla scala 1:100.000. foglio 113 – castelfiorentino. nuova tecnica grafica, roma. pantanelli d. (1875) – sui travertini della provincia di siena. soc. tosc. nat., proc. verb., 4-7. pedley h.m. (1990) – classification and environmental model of cool freshwater tufas. sedimentary geology, 6688, 143-154. pedley m., gonzalez martin j.a., ordoñez delgado s. & garcia del cura m.a. (2003) – sedimentology of quaternary perched springline and paludal tufas: criteria for recognition, with examples from guadalajara province, spain. sedimentology, 5500, 23-44. trabucco g. (1920) – stratigrafia, origine, età, applicazioni della lignite torbosa-xiloide del bacino di monte oliveto. boll. soc. geol. it., 5544, 314-324. 40 ms. ricevuto il 4 novembre 2003 testo definitivo ricevuto il 13 gennaio 2004 ms. received: november 4, 2003 final text received: genuary 13, 2004 e. capezzuoli & f. sandrelli imp.dall'aglio& geomorfologia e popolamento antico nella media valle del fiume cesano (marcheitalia) pier luigi dall’aglio1, giuseppe marchetti2, olivia nesci4, luisa pellegrini3, daniele savelli4 & gilberto calderoni5. 1dipartimento di archeologia dell’università di bologna 2dipartimento di ecologia del territorio dell’università di pavia 3dipartimento di scienze della terra dell’università di pavia 4dipartimento di scienze della terra dell’università di urbino “carlo bo” 5dipartimento di scienze della terra dell’università di roma “la sapienza” riassunto: dall’aglio p. l., marchetti g., nesci o., pellegrini l., savelli d., calderoni g., geomorfologia e popolamento antico nella media valle del fiume cesano (marche, italia).( it issn 0394-3356, 2004) la presente ricerca propone uno studio integrato del territorio, con la sovrapposizione dei dati geomorfologici con quelli storico-topografici, allo scopo di definire le trasformazioni più recenti del paesaggio. l’area studiata ricade nella media valle del fiume cesano (versante adriatico dell’appennino marchigiano), per la quale sono state riconosciute numerose fasi fluviali a cui sono riconducibili vari livelli di terrazzamento fluviale. le analisi effettuate e le testimonianze rinvenute permettono di individuare, soprattutto a partire dai terrazzi del “3° ordine”, fasi deposizionali con regime a canali intrecciati, che si sono intervallate a fasi a canali meandranti. l’assetto fisico del territorio costituisce la base delle scelte insediative del popolamento antico dettate dalla necessità ora di difesa dall’eventuale nemico ora di coltivazione dei campi. in particolare si giustifica l’ubicazione dell’importante città romana di suasa sulla sommità del terrazzo pleistocenico, in destra cesano, con motivazioni di tipo storico e geografico. nel contesto dell’interazione uomo–territorio, rilevante significato assume il periodo caratterizzato da un sensibile deterioramento climatico, riferibile al v-vi sec. a.d.: gli eventi alluvionali, riconducibili a quel periodo, vengono collegati non solo al peggioramento climatico ma anche, probabilmente, allo spopolamento dell’area che comportò l’abbandono dei terreni coltivati e delle opere di controllo idraulico. si può pertanto affermare che, nell’area studiata, i suddetti eventi alluvionali, innescati da fattori naturali, furono notevolmente amplificati dall’attività umana. abstract: dall’aglio p. l., marchetti g., nesci o., pellegrini l., savelli d., calderoni g., geomorphology and ancient settlement in the middle cesano river valley (marche, central italy). (it issn 0394-3356, 2004). this paper reports the preliminary results obtained by comparing geomorphologic, historic and topographic data with the aim of highlighting the most significant geomorphic changes which occurred in the landscape configuration. the study area embraces the middle cesano river valley (adriatic side of the marche apennines), an area where distinct fluvial evolution stages pointed out by individual terrace levels have been identified. starting from the so-called “3rd order” terrace alluvium (upper pleistocene-holocene pp. in age), several cut-and-fill stages have been recognised on the basis of field evidence, 14c dating of wood remnants and archaeological findings. specifically, braid-plain aggradation stages characterise the most part of the upper pleistocene terrace alluvium, whereas both late-upper pleistocene and early holocene deposits and terrace-surface morphology hint at a flluvial activity related to an overall meandering channel pattern. it is only in post-roman times that braiding was at first restored and then replaced by entrenching single straight channels. analogously, it has been verified that the physical features of the territory strictly controlled the settlement of the ancient population. both historical and geographical constraints account for the location of the roman town of suasa atop a pleistocene terrace on the right side of cesano river. as for man-environment interaction, it is worth stressing that through the v-vi centuries a.d. a marked climatic cooling triggered an aggradation pattern in the river valley whose effectiveness was boosted because the population drop was obviously paralleled by a progressive abandonment of agriculture as well as by hydraulic workings. parole chiave: morfologia fluviale, geoarcheologia, suasa, fiume cesano, marche. keywords: fluvial geomorphology, geoarchaeology, suasa, cesano river, marche. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 213-219 1. introduzione gli studi condotti in questi ultimi anni hanno messo sempre più in evidenza la necessità di leggere un territorio in modo integrato e non settoriale. solo così, infatti, è possibile cogliere appieno le caratteristiche dei vari paesaggi e individuare le modificazioni che hanno subito nel tempo, riconoscendo anche le cause, sia fisiche che antropiche, a cui sono riconducibili. l’esperienza maturata in questo settore ha ampiamente dimostrato che i livelli fondamentali per una simile lettura sono essenzialmente quello geomorfologico e quello storico-topografico, perché proprio dal rapporto tra l’uomo e il territorio partono molte delle trasformazioni che hanno prodotto il paesaggio attuale (dall’aglio, 2000). e’ dunque sul risultato della sovrapposizione tra analisi geomorfologica e ricostruzione dell’antico assetto del territorio che potranno inserirsi gli altri tematismi indispensabili per completare lo studio del paesaggio. al fine dell’applicazione di queste metodologie di indagine si è assunta come riferimento la media valle del fiume cesano, indubbiamente assai eloquente sotto questo punto di vista (dall’aglio, 2004). 214 p.l. dall’aglio et al. 2 lineamenti geomorfologici le fasi genetiche che hanno portato all’attuale conformazione della pianura alluvionale del fiume cesano sono varie e complesse (cfr.calderoni et al.,1991; coltorti, 1991). la piana lungo il tratto vallivo tra san lorenzo in campo e san michele al fiume (fig. 1), ampia mediamente 2 km, presenta bordi esterni netti e rettilinei che si raccordano con versanti caratterizzati da un forte dissesto sia superficiale che profondo. sui versanti sono presenti lembi di terrazzi alluvionali riferibili al “1° e 2° ordine dei terrazzi” della letteratura tradizionale (aa.vv., 1991; nesci et al., 1995 cum bibl.). e’ stato verificato che l’età di inizio della deposizione del corpo alluvionale del “3° ordine”, avvenuta su un substrato reso irregolare dalla presenza di alvei sepolti e interposizione di dossi, eccede la possibilità di misura del metodo del 14c (ca. 44.000 anni bp) e sulla base di varie considerazioni potrebbe collocarsi a 55.000/60.000 anni dal presente (calderoni et al., 1991, nesci et al., 1995). la principale incisione sul substrato, desunta dalle stratigrafie dei numerosi sondaggi eseguiti nell’area studio (nesci & savelli, dati inediti), pur essendo situata a sinistra dell’alveo attuale presenta lo stesso andamento rettilineo dell’odierna tratta dell’attuale cesano. la deposizione del principale corpo alluvionale non avvenne per aggradazione continua, ma secondo meccanismi di cutand-fill con formazione anche di terrazzi sepolti (calderoni et al., 1991). i depositi, prevalentemente costituiti da ghiaie con subordinati livelli e lenti sabbiose e limoso-argillose, sono riferibili a un fiume con canali intrecciati (fb di nesci & savelli, 1986, 1991). la parte alta dei depositi è quasi ovunque reincisa e rimodellata; vi compaiono facies sabbioso-ghiaiose a stratificazione inclinata depositate da canali meandranti in blando approfondimento (fs di nesci & savelli, 1986, 1991, fase 5 di coltorti, 1991), in discontinuità sui sottostanti depositi pleistocenici (fig. 2). l’approfondimento olocenico di alvei meandriformi, molto complesso, accompagnato e/o interrotto da eventi minori di aggradazione, è ben riconoscibile morfologicamente dalla presenza di ampi paleomeandri anche molto prossimi alla piana pleistocenica. questo particolare comportamento ha caratterizzato gran parte dell’olocene ed è continuato fino in fig.1 schema geomorfologico e distribuzione dei depositi alluvionali lungo il tratto del fiume cesano studiato. geomorphologic sketch and distribution of alluvial deposits for the studied reach of the cesano river valley. età romana. i dati geomorfologici, di cronologia isotopica e i reperti di varia natura a tutt’oggi disponibili non consentono tuttavia un’affidabile distinzione delle varie fasi che caratterizzarono l’evento. la città di suasa si estende (fig. 1) tanto sulla 215geomorfologia e popolamento ... sommità delle alluvioni terrazzate del pleistocene superiore che sull’evidente paleomeandro incassato di qualche metro all’interno di questo (coltorti, 1991). al di sotto di quest’ultimo livello terrazzato si riconoscono altri due ripiani, di cui quello superiore è limitato esterfig. 2 sezioni schematiche nei depositi contenenti i campioni datati. sezione 1 = fronte di cava nei pressi di san michele al fiume, sezioni 2 e 3 = sponda rispettivamente di destra e di sinistra di rio freddo (v. fig.1). l’attribuzione al 500-600 a.d. in sezione 1 si basa sulla età 14c di 1490-1820 b.p. di fig. 1; le analoghe attribuzioni nelle sezioni 2 e 3 derivano da correlazioni di terreno (v. testo per una più approfondita discussione). lithostratigraphic setting of the dated samples. section 1 = quarry nearby st. michele al fiume, sections 2 and 3 = right and left rio freddo banks, respectively (see fig.1). 500-600 a.d. age in section 1 is inferred from 1490-1820 14c ages in fig. 1; the same 500-600 a.d. (?) ages in sections 2 and 3 are derived mainly from field evidence. see the text for a more detailed discussion. fig. 3 la città romana di suasa. a: anfiteatro; b: teatro tuttora sepolto ; c: area della domus dei coiedii; d: area del foro. the roman town of suasa. a: excavated amphiteater; b: theater still buried; c: coiedii domus; c: forum. 216 namente da una serie di scarpate semicircolari ricollegabili a paleomeandri più stretti e con più alto indice di sinuosità di quelli prodotti dall’evento precedente. la stratificazione inclinata e le chiare strutture sedimentarie tipiche di un regime a meandri confermano l’evidenza morfologica (coltorti, 1991). nei depositi che affiorano lungo il rio freddo (fig. 1), verosimilmente riferibili a queste fasi, sono stati rinvenuti numerosi macroframmenti vegetali, alcuni identificati come semi e foglie di quercus sp., che hanno fornito un’età 14c di 2970±70 anni bp (1310-1050 cal. a.c., rome-544). la data permetterebbe di ipotizzare una prima fase, pre-romana, in cui il fiume cesano si presentava alquanto sinuoso, con sponde relativamente stabili, facilmente percorribili e attraversabili e ricoperte da vegetazione simile all’attuale. alcuni affioramenti su un vecchio fronte di cava in sponda destra del f. cesano (fig. 2) contenevano una serie di macroresti di quercus sp., la cui datazione ha fornito le età di 1560±65 anni bp, (420-570 cal a.d., rome-540), 1540±65 anni bp (430-600 cal a.d., rome542), 1490±65 anni bp (440-650 cal a.d., rome-543) e 1820±65 anni bp (90-320 cal a.d., rome-541). osserviamo che tre (rome-540, -542 e –543) delle quattro date sono statisticamente indistinguibili e forniscono un’età media ponderata di 1530±40 anni bp (430-600 cal a.d.), mentre l’età di rome-541 è più antica di ca. 300 anni. quest’ultima data potrebbe suggerire una deposizione in più riprese dei sedimenti campionati anche se non può essere escluso un invecchiamento dovuto al fatto che i reperti datati derivano da vegetazione superiore a lunga vita. sempre da affioramenti lungo il rio freddo sono stati campionati framfig. 4 carta della distribuzione del popolamento antico nella media valle del fiume cesano. map showing the estimated distribution of ancient population over the middle cesano river valley. p.l. dall’aglio et al. 217 menti, visibilmente arrotondati per trasporto, di laterizi romani associati a macroframmenti di quercia anch’essi visibilmente fluitati. le due date 14c ottenute per questi ultimi, 4250±75 e 4550±75 anni bp (rispettivamente rome-545 e –539, che calibrano a 2930-2630 e 33703090 cal a.c.) sono in aperto contrasto con l’età attribuita alla ceramica. tenendo presente che tanto i resti vegetali che quelli archeologici non erano in giacitura primaria, la discrepanza di età rivela che la loro associazione è puramente fortuita e non riflette una origine comune e quindi tanto le date isotopiche che quelle archeologiche forniscono dei termini post-quem per l’aggradazione dei sedimenti contenenti i reperti. l’associazione di materiali che si dispongono su di un arco cronologico di circa due millenni indicherebbe un input poligenico proveniente da uno smantellamento di uno, o più, depositi precedenti ovvero la presenza di un ulteriore, sottile orizzonte alluvionale relativamente “antico” (fig. 2), non distinguibile sul terreno a causa delle cattive condizioni di affioramento. le quattro date potrebbero suggerire comunque che la messa in posto dei depositi dell’unità alluvionale campionata è avvenuta almeno in due riprese, circoscritte tra i secoli i e iv e v e vi a.d. il fatto poi che la quasi totalità dei resti datati si concentrino tra il v e vi secolo può essere un indizio di un intensificarsi degli eventi alluvionali, fenomeno del resto in linea con quanto si conosce sull’evoluzione climatica generale. in questo periodo, infatti, tutti gli autori collocano un peggioramento climatico generalizzato, con un aumento della piovosità e una temperatura mediamente più bassa di circa 2° rispetto all’attuale (pinna, 1996). a quote poco inferiori o talora corrispondenti a quelle dei depositi precedentemente descritti, si rilevano le tracce di un più recente percorso fluviale, delimitato da scarpate nette e prevalentemente rettilinee. la presenza di barre longitudinali, laterali e linguoidi ciottolose testimonia un regime a canali intrecciati (coltorti, 1991). successivamente a questa fase il fiume si è incassato profondamente, assumendo un corso prevalentemente rettilineo molto simile all’attuale. la superficie alluvionale, corrispondente alla fase 2 di coltorti (1991), viene datata anteriormente agli anni ’50; successivamente il fiume subì un ulteriore approfondimento di ca. 10 metri raggiungendo la posizione attuale. 3. il popolamento antico i più antichi insediamenti nella media valle del cesano sono testimoniati da ritrovamenti, in siti ubicati sull’alto ripiano terrazzato di miralbello, dell’età del bronzo medio e recente (xvi-xii secolo a. c.) e della piena attestazione del periodo piceno (viii-v secolo a.c.). tuttavia il maggior numero di ritrovamenti archeologici è di età romana, periodo in cui oltre ad un significativo aumento della densità di popolamento dell’area fu fondata la città di suasa sul terrazzo alla destra del fiume. questo centro, sorto nel iii secolo a.c. come praefectura lungo la strada che dalla conca di sassoferrato scende verso la costa, si trasforma quindi in un vero centro abitato nel corso del i secolo a.c.. la nascita del centro abitato si ricollega alle assegnazioni di terre stabilite con la lex flaminia de agro gallico et piceno viritim dividundo del 232 a.c. (dall’aglio et al., 1991). il conseguente sfruttamento di queste terre ne comportò una decisa antropizzazione, con conseguente disboscamento, regimazione dei corsi d’acqua e tracciamento della centuriazione. la guerra gotica prima e l’invasione longobarda poi, portarono nel corso del vi secolo alla scomparsa della città ed allo spopolamento della pianura di fondovalle. il ruolo di centro ordinatore del territorio, già assolto da suasa, venne di seguito assolto dall’abbazia di san lorenzo in campo. questa fu eretta nell’viii secolo sulla riva opposta del fiume, lungo il diverticolo della via flaminia che da cagli arrivava alla costa, all’apice di un conoide di un affluente del cesano, ossia in posizione più alta rispetto alla piana del fondovalle principale e pertanto al sicuro tanto da esondazioni del fiume quanto da impaludamenti (dall’aglio, 1994). 4. conclusioni i risultati dell’analisi comparata dei dati geomorfologici e storico-topografici dimostrano, anche nel caso di questo studio, che i criteri di scelta per l’ubicazione di un insediamento sono legati, soprattutto in età romana, ai risultati di un’attenta lettura dell’assetto fisico del territorio nonché, per quanto poteva essere percepito, della sua evoluzione. non è quindi casuale che i resti delle fattorie romane si rinvengano su quelle unità morfologiche (essenzialmente i terrazzi di fondovalle a ridosso del versante e i pianori situati lungo crinale e versante) che offrono le condizioni più vantaggiose per la pratica dell’agricoltura. viceversa in età preromana, quando la situazione politica era caratterizzata da una maggiore instabilità e insicurezza, gli insediamenti tendono a collocarsi prevalentemente in zone sopraelevate e che quindi potevano essere facilmente difese e consentivano un controllo visivo sul territorio circostante (dall’aglio, 1994). a questo intrecciarsi di motivazioni geografiche e storiche non si sottrae neppure l’ubicazione della città romana di suasa. essa infatti è collocata su di un terrazzo alluvionale di fondovalle alla destra del cesano, denominato pian volpello, che è il primo terrazzo di una certa ampiezza che si incontra provenendo dalla conca di sassoferrato seguendo il solco vallivo di un affluente di destra del cesano, il t. nevola. in altri termini, la città nasce lungo la strada che univa sentinum alla costa correndo parallela all’altro asse stradale che da sentinum raggiungeva sena gallica, la più antica colonia dedotta dai romani nelle marche, seguendo la valle del misa (dall’aglio, 1991). questo legame tra suasa e la viabilità gravitante su sentinum dimostra come il nostro centro sia nato prima della apertura del sistema stradale incentrato sulla via flaminia, aperta, come noto, nel 220 a.c.: il diverticolo che unisce la via flaminia a senigallia passando per cagli e citato nelle fonti itinerarie (it. ant., 315,7-316,5) corre infatti sull’opposta riva del cesano. se dunque suasa fosse nata quando il sistema della flaminia era ormai consolidato, sarebbe sorta sulla sinistra del fiume, nella zona, ad esempio, di san lorenzo in campo e non sulla destra. la scelta del terrazzo di pian volpello, poi, è dovuta da un lato, come si è detto, alla sua ampiezza che consente l’impianto delle strutture proprie di una città, come il foro, il teatro, l’anfiteatro, oltre alle case di abitazione che, come noto, in età romana si sviluppavano più in geomorfologia e popolamento ... 218 ampiezza che in altezza, e all’essere comunque alto rispetto al fiume e quindi al riparo delle normali ondate di piena. la romanizzazione non si concretizzò solo nella nascita di un nuovo centro urbano, ma, ancor prima che suasa divenisse una città, con l’assegnazione delle terre conquistate ai coloni, assegnazione che avvenne nel 232 a.c. in seguito alla lex flaminia de agro gallico et piceno viritim dividundo (paci, 1998). tale operazione comportò il tracciamento della centuriazione al fine di individuare i vari lotti da assegnare ai coloni e, di conseguenza, alla nascita di un paesaggio dominato dal coltivo e da un regolare disegno dei campi. se si analizza l’attuale organizzazione della campagna in questo tratto di valle è facile notare come quella regolarità imposta dagli antichi agrimensori sia pressoché cancellata (bonora & dall’aglio, 1991). dal momento che, di norma, nelle nostre campagne si hanno notevoli persistenze della centuriazione è necessario interrogarsi sulle cause che hanno portato qui alla nascita di un assetto territoriale completamente avulso da quello di età romana. per giustificare una simile cancellazione si invoca spesso il peggioramento climatico di età tardoantica (e.g. veggiani, 1973). in altri termini si dice che l’aumento della piovosità ha causato alluvioni disastrose, come quelle citate da paolo diacono per il 589 e che per questo vanno sotto il nome di “diluvium di paolo diacono” (paul. diac., hist. lang., iii, 23-24), che avrebbero cancellato qualsiasi traccia dell’organizzazione territoriale precedente. in realtà l’aumento della piovosità, per quanto accompagnato da una generale diminuzione della temperatura e da un aumento delle burrasche che, nel caso dei fiumi marchigiani, avrebbero ulteriormente favorito, specie nelle piane costiere, alluvioni e rigurgiti ostacolando il già spesso difficile deflusso delle acque in mare (marabini 1996), non è in grado da solo di determinare variazioni nell’andamento dei corsi d’acqua e stravolgimenti nella geografia e nell’organizzazione del territorio. perché un’organizzazione territoriale perfettamente coerente con la geografia fisica di un territorio com’era la centuriazione venga del tutto o in parte cancellata è necessario che accanto a fenomeni naturali, quale, appunto, il peggioramento climatico, ci siano anche fattori antropici (dall’aglio, 1998). se infatti fosse sufficiente solo il fatto climatico, dovremmo trovare analoghi esiti anche in occasione della c.d. piccola età glaciale, cosa che invece non accade proprio grazie alla forte presenza antropica sul territorio. viceversa a partire dal iv secolo si ha un progressivo calo demografico, che raggiunge il suo culmine alla metà del vi secolo, all’epoca della guerra grecogotica, e che ha come conseguenza il restringimento di quasi tutti i centri urbani e addirittura la scomparsa di molti di questi, come ad esempio avviene per suasa, o la loro riduzione a semplici villaggi (dall’aglio, 2002). questo spopolamento non interessa, ovviamente, solo le città, ma anche le campagne dove si ha prima di tutto il venir meno della normale manutenzione dei canali di drenaggio e di tutte quelle opere che consentivano di controllare i vari corsi d’acqua. sono così possibili variazioni nell’andamento dei corsi d’acqua e l’innesco di fenomeni di impaludamento e di dissesto idraulico, con una ripresa anche dell’incolto, in primo luogo del bosco. il paesaggio coltivato e regolare di età romana, con un fitto popolamento delle campagne, si trasforma progressivamente in un paesaggio più vicino a quello preromano, caratterizzato da boschi, paludi, da corsi d’acqua non più regimati e da un popolamento decisamente più scarso e che nelle vallate marchigiane prediligeva sopratutto le alture lungo i crinali perché naturalmente difese a scapito dei fondovalle, più esposti e quindi non più insediati. anche la cancellazione della centuriazione nella media valle del cesano va dunque inquadrata in questo mutato equilibrio tra uomo e ambiente e quindi come il risultato di un’azione combinata di eventi naturali e antropici, azione alla quale vanno attribuiti anche i cambiamenti di regime e di caratteristiche del cesano (cfr. coltorti 1997). del resto la presenza qui di ampie zone boscate è indirettamente confermata dal nome, san lorenzo in sylvis, del monastero che nel primo medioevo viene costruito sulla sinistra del cesano, lungo l’antico diverticolo della via flaminia (dall’aglio, 1991). sarà questo monastero, per altro collocato all’apice di un conoide di un affluente del cesano in modo da trovarsi in una posizione alta rispetto la pianura circostante, a ereditare, in un certo senso, il ruolo dell’antica e ormai scomparsa suasa, e a favorire la rioccupazione e la rimessa a coltura della media valle. nel pieno medioevo quest’operazione può dirsi conclusa, tanto che il centro sorto attorno al monastero cambia nome per assumere la denominazione attuale di san lorenzo in campo, attributo che chiaramente testimonia l’avvenuta trasformazione del paesaggio (dall’aglio, 1994). tale nuova sistemazione avviene però su di un quadro fisiografico diverso da quello di età romana e questo comporta l’impianto di un disegno differente da quello a suo tempo tracciato dagli agrimensori romani. bibliografia autori vari (1991) l’ambiente fisico delle marche. geologia, geomorfologia, idrogeologia. carta geologica alla scala 1:100.000. s.e.l.c.a. firenze. bonora g. & dall’aglio p. l. (1991) la centuriazione della valli del misa e del cesano. in: dall’aglio p. l., de maria s. & mariotti a. (eds.) “archeologia nelle vallate marchigiane: le valli del misa e del nevola”. electa editori umbri perugia, pp. 28-34. calderoni g., nesci o. & savelli d. (1991) terrace fluvial deposits from the middle basin of cesano river (nothern marche apennines): reconnaissance study and radiometric constraints on their age. geogr. fis. din. quat., 14, 2, pp.201-207. coltorti m. (1991) modificazioni morfologiche oloceniche nelle piane alluvionali marchigiane: alcuni esempi nei fiumi misa, cesano e musone. geogr. fis. din. quat., 14, 1, pp. 73-86. coltorti m. (1997) human impact in the holocene fluvial and coastal evolution of the marche region, central italy. catena, 30 , pp. 311-335. dall’aglio p. l., de maria s. & mariotti a. (1991) archeologia delle valli marchigiane misa, nevola e cesano. electa editori umbri, perugia. dall’aglio p. l. (1991) la viabilità romana. in archeologia nelle vallate marchigiane: le valli del misa e del nevola, electa editori umbri, perugia, pp. 12-23. dall’aglio p. l. (1994) il popolamento romano dell'ager suasanus: prime considerazioni ed ipotesi. in: "le p.l. dall’aglio et al. marche: archeologia. storia. territorio", v (199193), pp. 151-157. dall’aglio p. l. (1998) il diluvium di paolo diacono e le modificazioni ambientali tardoantiche: un problema di metodo. ocnus, 5 (1997), pp. 97-104. dall’aglio p. l. (2000) geomorfologia e topografia antica. la topografia antica, bologna, pp.177-192. dall’aglio p. l. (2002) l’età romana, in: sulle tracce del passato, stibu, urbania, pp. 17-26. dall’aglio p. l. (2004.) per una “carta del rischio archeologico” della valle del cesano. “atti del convegno sulla carta archeologica regionale”. fiastra, giugno 2002, in stampa. marabini f. (1996) evoluzione dell’ambiente costiero in tempi storici e le variazioni climatiche, il quaternario. 9, pp. 201-204. nesci o. & savelli d. (1986) cicli continentali tardoquaternari lungo i tratti vallivi mediani delle marche settentrionali. geogr. fis. dinam. quat., 9, pp. 192-211. nesci o. & savelli d. (1991) successioni alluvionali terrazzate nell’appennino nord-marchigiano. geogr. fis. din. quat., 14, 1, pp. 149-172. nesci o., savelli d., calderoni g., elmi c. & veneri f. (1995) le antiche piane di fondovalle nell'appennino nord-marchigiano. in: castiglioni g.b. & federici p.r. (eds.) "assetto fisico e problemi ambientali delle pianure italiane". mem. soc. geogr. it., 53, pp. 293-312. paci g. (1998) umbria ed agro gallico a nord del fiume esino, picus, 18, pp.89-118 pinna m. (1996) le variazioni del clima, franco angeli, milano. veggiani a. (1973) prime considerazioni su due periodi di dissesti idrogeologici nella pianura padana in epoca storica, atti 3 conv. naz. studi problemi geologia applicata, firenze, pp. 157-164. 219 ms. ricevuto il 4 maggio 2004 testo definitivo ricevuto il 20 ottobre 2004 ms. received: may 4, 2004 final text received: october 20, 2004. geomorfologia e popolamento ... imp.giaccio& la risposta ambientale ed umana alle oscillazioni climatiche sub-orbitali dell’ois3: evidenze geoarcheologiche dalla piana di colfiorito (appennino centrale) biagio giaccio1, mario federico rolfo2, simone bozzato2, fabrizio galadini1, paolo messina1, mara silvestrini3 & andrea sposato1 1cnr, istituto di geologia ambientale e geoingegneria, sezione roma “tor vergata” 2dipartimento di storia, università di roma “tor vergata” 3soprintendenza archeologica per le marche, ancona biagio.giaccio@igag.cnr.it riassunto: giaggio b. et al., la risposta ambientale ed umana alle oscillazioni climatiche sub-orbitali dell’ois3: evidenze geoarcheologiche dalla piana di colfiorito (appennino centrale). (it issn 0394-3356, 2004). un ampia trincea ha permesso di investigare una successione stratigrafica del pleistocene recente al margine nord-orientale del bacino intermontano della piana di colfiorito (umbria-marche). lo scavo attraversa lo spartiacque appenninico a circa 760 m s.l.m. (sella di fonte delle mattinate; fdm) lungo una delle principali vie intermontane di questo settore della catena. studi integrati, lito-pedostratigrafici e archeologici, descrivono una dettagliata storia degli eventi geo-ambientali e dell’occupazione umana di quest’area strategica nel corso dell’ultimo bond cycle dello stadio isotopico 3 (ois3; ca. 38-29 gisp2 ka b.p.). la parte più bassa della sequenza è rappresentata da sedimenti di un sistema fluviale costituito da un canale attivo e un’adiacente piana soggetta alternativamente a episodi di esondazione e di pedogenesi, questi ultimi testimoniati da un profondo paleosuolo (vertisuolo) datato a 31.510±860-30.970±31028.910±390-28.300±790 14c anni b.p. il paleosuolo è sepolto da diversi metri di sedimenti ghiaioso-limosi ascrivibili ad un sistema di conoide alluvionale attivo fra 25.930±325 e 24.150±120 14c anni b.p. il paleosuolo e due sottili livelli limosi alla base delle alluvioni hanno restituito manufatti del paleolitico superiore ed altre tracce archeologiche compatibili con brevi, ma ripetuti episodi di occupazioni umana. i dati cronologici e stratigrafici disponibili indicano infatti che l’area del sito fu frequentata, probabilmente in maniera sistematica, durante tutto il periodo di formazione del paleosuolo fino ai primi episodi di sedimentazione alluvionale che ne hanno determinato il seppellimento. in termini di cronologia radiocarbonio questo periodo copre almeno l’intervallo compreso fra ca. 31 e 26 ka b.p. la fase di pedogenesi a fdm, contemporanea ai primi episodi di frequentazione umana, risulta coeva ad un periodo di clima mite che ha visto in un’ampia area dell’appennino centrale la formazione di un diffuso paleosuolo datato nell’intervallo 33-29 14c ka b.p. e correlato ai primi millenni dell’ultimo ciclo di bond dell’ois3 (greenland interstadial 8-7; ca. 38-34 cal ka b.p. in anni gisp2 icecore). la successiva fase di sedimentazione alluvionale e di contemporaneo abbandono del sito può essere invece correlata all’episodio di estremo raffreddamento dell’heinrich event 3 (ca. 30-29 gisp2 ka b.p.) che chiude il summenzionato ciclo climatico di bond. la coincidenza dell’abbandono di quest’area strategica con l’inizio dell’he3 suggerirebbe che durante l’ois3 le modificazioni geoambientali associate a questi eventi condizionarono pesantemente le strategie dei gruppi paleolitici, probabilmente limitando o modificando la mobilità nelle aree montane più interne dell’appennino centrale. abstract: giaccio b. (et al.), geoenvironmental and human response to the sub-orbital climatic oscillations of the ois3: geoarchaeological evidence from the colfiorito plain (central italy). (it issn 0394-3356, 2004). the colfiorito plain is a plio-quaternary tectono-karstic intermontane basin of the central apennines, located at ~750 m a.s.l. a large excavation was recently made across the fonte delle mattinate (fdm) saddle, an important mountain pass along one of the main natural way of the region connecting the tyrrhenian and adriatic side. combined, litho-pedostatigraphic and archaeological analyses describe a detailed geoenviromental evolution and correlated human occupation history of this strategic area in the course of the last bond cycle of the oxygen isotope stage 3 (ois3; ca. 38-29 gisp2 ka b.p.). the lowest part of the succession is related to a fluvial depositional system, represented by an active channel and an adjacent floodplain which was in turn subjected to overbanking episodes and pedogenetic processes testified by an evolved paleosol (vertisol) dated to 31.510±860-30.970±310-28.910±390-28.300±790 14c yr b.p. the paleosol is buried by a thick sequence of gravely silty sediments ascribable to debris-flow-dominated fan depositional system. radiocarbon dates from the base and top of this unit place the this environmental shift between 25,930±325 b.p. and 24,150±120 b.p. the paleosol and the two silty levels at the base of the alluvial fan sediments yielded early upper palaeolithic artefacts and associated features consistent with brief, but frequent episodes of human occupation. the available stratigraphic and radiocarbon data indeed indicate that human occupation at fdm area was probably systematic, and lasted the whole period of the soil formation up until the first alluvial episodes responsible for its burial. in terms of the radiocarbon chronology, this period spans at least the interval between 31,510±860, age of the oldest anthropogenic charcoals embedded in the paleosol, and 25,930±325, date of the uppermost documented archaeological layer of the sequence. the site being definitively abandoned after this latter date. based on lithostratigraphic data and chronology the fdm paleosol has been correlated with a pedomarker well documented throughout central apennine. furthermore, regional pollen information and tephrochronological data suggest that the formation of both fdm and central apennine paleosol(s) occurred during a mild and wet climatic phase corresponding to the firsts millennial of the last bond cycle of the ois3 (greenland interstadial 8-7; ca. 38-34 gisp ka b.p. the subsequent co-occurrence of geoenvironmental change and human abandonment can be correlated with the heinrich event 3 (he3; ca. 30-29 gisp2 ka b.p.), the last coldest episode of the above mentioned bond cycle. such site evidence for synchronous geoenvironmental and human responses to the he3, suggests that during the ois3 the environmental changes related to the hes had a significant impact on palaeolithic communities, probably limiting or modifying their mobility in the central apennine mountains. parole chiave: stadio isotopico 3, oscillazioni climatiche sub-orbitali, modificazioni ambientali, paleolitico superiore, italia centrale. keywords: oxygen isotope stage 3, sub-orbital climatic oscillations, environmental modifications, upper palaeolithic, central italy . il quaternario italian journal of quaternary sciences 17(2/1), 2004, 231-247 232 b. giaccio et al. 1. introduzione l’identificazione della marcata variabilità climatica dell’ultimo glaciale, ben evidenziata per la prima volta dai record nord atlantici e groenlandesi (es. bond et al., 1992; dansgaard et al. 1993; grootes et al., 1993), ha posto da oltre un decennio al centro degli interessi di un vasto campo delle scienze del quaternario lo studio della variabilità spazio-temporale e dell’impatto geoambientale dei cicli climatici suborbitali noti come cicli di dansgaard/oeshger (d/o) e heinrich events (hes) in tutti gli archivi naturali terrestri (voelker, 2002, per una recente ampia sintesi internazionale). nel panorama delle ricerche in corso in questo ambito sono state evidenziate marcate e rapide variazioni anche nei sistemi vegetali e negli ambienti marini della regione mediterranea (es. watts et al., 1996; allen et al., 1999; chaco et al., 1999; paterne et al., 1999); variazioni che in base a più recenti studi risulterebbero in fase con i cicli climatici sub-orbitali delle alte latitudini (roucoux et al., 2001; moreno et al., 2002; sánchez goñi et al., 2000; 2002). nel loro complesso questi studi indicano l’alternanza di periodi relativamente caldo-umidi e freddo-aridi rispettivamente correlati alle fasi interstadiali e stadiali dei cicli di d/o, con estremi di aridità e raffreddamento durante gli hes. ancora largamente incomplete restano invece le attuali conoscenze circa il significato stratigrafico e gli effetti di questi eventi climatici sull’evoluzione degli ambienti subaerei mediterranei (es. giraudi, 1996; mokhtari fard, 2001; giaccio et al., 2004a). solo recentemente inoltre si sta ponendo l’attenzione su questa eccezionale variabilità climatica come potenziale fattore coinvolto nei processi di modificazione bio-culturale del pleistocene recente europeo (es. giraudi & mussi, 1999; d’errico & sánchez goñi, 2003; fedele et al., 2003; giaccio et al., 2004b). una delle principali cause all’origine di queste significative lacune risiede senza dubbio nei limiti intrinseci degli archivi subaerei (scarsa risoluzione, presenza di ampie e frequenti discontinuità, difficoltà di datazione e correlazione con le curve paleoclimatiche regionali e super-regionali ad alta risoluzione, scarsa rilevanza degli indicatori paleoclimatici, ...), che al momento relegano queste sequenze ad un ruolo marginale negli studi della variabilità climatica ad alta frequenza. è innegabile tuttavia che queste rappresentano comunque le uniche fonti di informazione diretta per ricostruire le modificazioni fisiche degli ambienti subaerei e più in generale le dinamiche interattive del sistema uomo-ambiente. in questa prospettiva è stata investigata una successione del pleistocene superiore al margine nordorientale del bacino intermontano della piana di colfiorito (umbria-marche) in corrispondenza dello fig. 1 veduta panoramica e modello tridimensionale del terreno della piana di colfiorito con ubicazione del sito di fonte delle mattinate (fdm). panoramic view and digital elevation model of the colfiorito plain with location of the fonte delle mattinate (fdm) site. spartiacque appenninico (fig. 1). evidenze lito-pedostratigrafiche descrivono la storia dell’evoluzione ambientale locale nel corso dell’intervallo 32-18 14c ka b.p., rivelando con particolare dettaglio e risoluzione stratigrafica gli episodi degli ultimi nove millenni dello stadio isotopico 3 (ois3), un periodo che ha visto in rapida successione le più marcate oscillazioni interstadiali-stadiali dell’ultimo glaciale. la sequenza indagata ha inoltre restituito importanti tracce di ripetute occupazioni umane ascrivibili alle prime fasi del paleolitico superiore. ciò ha permesso di comparare, indipendentemente da ulteriori ed incerte correlazioni cronologiche, dati archeologici e paleoambientali, e quindi di valutare contestualmente le potenziali interazioni fra i processi climatico-ambientali e la frequentazione umana dell’area. dopo una descrizione generale del contesto stratigrafico e archeologico, viene proposta un’ipotesi di correlazione della successione in esame con altre sequenze continentali appenniniche, nonché un primo tentativo di inquadrare l’evoluzione ambientale nell’ambito più generale della ciclicità climatica dell’ois3. il successivo esame combinato di entrambi i gruppi di dati, geologici e archeologici, suggerirebbe una significativa relazione fra occupazione umana e modificazioni ambientali, a loro volta controllate dalle principali oscillazioni climatiche millenarie dell’ultimo bond cycle dell’ois3 ed in particolare dall’he3. i risultati sono infine discussi sia in termini di implicazioni geoarcheologiche locali, sia nella più ampia prospettiva delle evidenze emerse nell’area mediterranea. 2. il quadro geologico e geomorfologico il bacino di colfiorito è una depressione intermontana di origine tettono-carsica formatasi durante la fase estensionale che ha caratterizzato la catena appenninica nel plio-quaternario (calamita et al., 1998; coltorti et al., 1998; messina et al., 2002). la piana si sviluppa ad una quota media di 750 m s.l.m. ed è bordata da rilievi con cime che si elevano a circa 1000-1300 m s.l.m. (fig. 1). sul suo fianco nord-orientale è presente una faglia normale, con direzione nw-se ed attività quaternaria, che rappresenta l’elemento strutturale principale della depressione. questa faglia mette a contatto i calcari meso-cenozoici della dorsale montuosa con i depositi quaternari della piana, costituiti da limi lacustri a cui si intercalano, in prossimità dei versanti, ghiaie di conoide alluvionale. sui versanti e/o alla loro base sono presenti depositi clastici grossolani variamente cementati. la piana di colfiorito è separata dalla valle del fiume chienti dalla sella di fonte delle mattinate (fdm; ca. 770 m s.l.m), costituita in gran parte da un deposito di frana che impedisce il naturale deflusso delle acque verso il mare adriatico (g a l a d i n i et al., 2003). attualmente il deflusso è assicurato da una serie di canali drenanti e da una galleria artificiale del xv secolo. questo sistema drenante è stato recentemente sostituito da una nuova galleria che attraversa la sella di fdm. prima della costruzione di tali opere, le prime risalenti al primo/secondo secolo a.d. (galadini et al., 2003), le acque defluivano in una serie di inghiottitoi di origine carsica tuttora in parte attivi ai bordi del bacino (messina et al., 2002). 233la risposta ambientale ed umana ... 3. stratigrafia e contesto paleoambientale 3.1. caratteri pedo-sedimentari la successione stratigrafica della sella di fdm è stata ricostruita attraverso lo studio di un’ampia sezione messa in luce nel corso dei lavori connessi alla realizzazione della nuova galleria drenante. la trincea attraversa il settore meridionale della sella esponendo i depositi per una profondità massima di circa 15 m e per un’estensione laterale di diverse decine di metri. il substrato della successione in esame è costituito da depositi caotici, affioranti esclusivamente in un settore limitato a nord della trincea, riferibili ad una paleofrana che ha fortemente condizionato l’evoluzione geoambientale locale (galadini et al., 2003) (fig. 2). la discreta estensione dell’affioramento ed un accurato esame lito-pedostratigrafico hanno permesso di distinguere nell’ambito della successione cinque diverse unità (fig. 3). una sintetica descrizione delle principali caratteristiche lito-pedologiche e sedimentologiche delle unità è fornita in figura 3. 3.2. sistema ambientale e sua evoluzione unità a-b l’associazione di litofacies e la geometria interna dell’unità a mostrano tutti i principali elementi caratteristici di un deposito di point-bar, ben individuato soprattutto per la presenza dell’elemento architetturale dominante di tipo lateral accrection (fig. 2) (miall, 1988; 1996). tale struttura sedimentaria è tipica dei sistemi fluviali tipo gravel-bed wandering e/o gravelbed meanderig caratterizzati da un singolo canale principale attivo, presenza di isole e scattered bars e una sinuosità da medio-alta (gravel-bed wandering river) ad alta (gravel-bed meandering river) (miall, 1996). questi sistemi sono compatibili con diverse condizioni di gradiente topografico e con regimi di corrente da torrenziale a sluggish (jackson, 1978). i caratteri di litofacies e pedofacies che contraddistinguono l’unità b suggeriscono invece meccanismi deposizionali legati a fenomeni di esondazione. i rapporti stratigrafici fra le unità a e b suggerirebbero inoltre che entrambe rappresentino gli elementi del medesimo sistema deposizionale fluviale costituito da un canale attivo (unità a) e da un’adiacente floodplain soggetta alternativamente a episodiche fasi di sedimentazione pelitica, in occasione dei fenomeni di esondazione, e a processi subaerei pedogenetici (unità b). tale interpretazione è in accordo con il grado di maturità del paleosuolo che aumenta nella direzione opposta a quella di migrazione del canale (figg. 2 e 3) (bown & kraus, 1987). l’insieme dei caratteri del paleosuolo (fig. 3), ed in particolare la diffusa presenza di slickensides, suggerirebbero che si tratti di un vertisuolo. pur considerando le modeste estensioni dell’affioramento, i caratteri pedo-sedimentari dell’insieme delle unità a-b suggeriscono la presenza di un sistema fluviale del tipo appena descritto attivo in un momento successivo all’evento franoso e sub contemporaneo alla formazione del paleosuolo datato nell’intervallo di circa 32-28 14c ka b.p. (figg. 2 e 3; tab. 1). considerando il contesto topografico è possibile interpretare tale segmento fluviale come elemento di una più ampia rete idrografica drenata da uno o più inghiottitoi carsici presenti nel settore settentrionale del bacino di colfiorito (messina et al., 2002). 234 f ig . 2 s c h e m a s tr a ti g ra fic o e p a rt ic o la ri f o to g ra fic i d e lla s u c c e ss io n e d i f o n te d e lle m a tt in a te . s tr at ig ra p h ic s c h e m e a n d s o m e p h o to g ra p h ic d e ta ils o f th e f o n te d e lle m at ti n at e s e q u e n c e . b. giaccio et al. 235 f ig . 3 p ri n c ip a li c a ra tt e ri p e d o -s e d im e n ta ri d e lla s e q u e n za d i f o n te d e lle m a tt in a te . m ai n p e d o -s e d im e n ta ry c h ar ac te rs o f th e f o n te d e lle m at ti n at e s e q u e n c e . la risposta ambientale ed umana ... 236 unità c l’associazione di facies di questa unità è in larga misura indicativa di sedimenti generati da flussi di massa. le forme lenticolari dei singoli corpi ghiaiosi, l’assenza di embriciature, lo scarso grado di stratificazione e gradazione e la presenza di abbondante matrice sono compatibili con meccanismi deposizionali da debris flow. le litofacies più frequenti (gcm) indicano la prevalenza di pseudo-plastic debris flow generati da flussi viscosi o turbolenti a bassa energia e più occasionali clast-rich debris flow e plastic debris flow (gci e gmm) generati a più alta energia (miall, 1996). i rari intervalli di litofacies gt suggeriscono la presenza sporadica di flussi trattivi confinati in piccoli canali effimeri, mentre gli intervalli pelitici sono riconducibili a depositi da esondazione confinati, prevalentemente, nelle depressioni esistenti fra i singoli lobi di ghiaia, generate dalle forme biconvesse dei debris flow. questa associazione è compatibile con un sistema deposizionale di conoide alluvionale, classificabile come debris-flowdominated fan (stanistreet & mccarthy, 1993) o “true” fan (blair & mcpherson, 1994) attivo nell’intervallo 25.930±325-24.150±120 b.p. 14c anni b.p (figg. 2 e 3). unità d-e la natura prevalentemente siltosa dell’unità d suggerisce una sedimentazione in ambiente lacustre-palustre. le geometrie interne e la morfologia esterna delle ghiaie gp, intercalate ai limi, sono invece interpretabili come barre trasversali che indicano l’attivazione episodica di correnti trattive e flussi canalizzati diretti verso la soglia. entrambi questi elementi indicano una fase di innalzamento del livello del lago con la formazione di un emissario in un periodo compreso tra 24.150±120 e 18.480±140 14c anni b.p. (figg. 2 e 3). gli indizi di moderati processi di pedogenesi al top dei livelli dell’unità d indicherebbero un abbassamento del livello lacustre e l’instaurarsi di condizioni di sostanziale stabilità intorno a ca. 18 14c ka b.p. questa fase di relativa stabilità è in seguito interrotta dalla ripresa della sedimentazione di conoide alluvionale dell’unità e (figg. 2 e 3). 4. contesto archeologico 4.1. aspetti archeostratigrafici, tafonomici e processi di formazione del sito nell’ambito della successione sono stati riconosciuti tre livelli contenenti chiare tracce di frequentazione umana del paleolitico superiore. questi corrispondono alla parte alta del paleosuolo (unità b) e ai due orizzonti pelitici alla base dell’unità c (figg. 2 e 3). i tre livelli hanno un’età compresa tra 31.510±860, la più antica fra le misure 14c dei carboni antropogenici contenuti nel paleosuolo (tab. 1; fig. 3), e 25.930±325 14c anni b.p., data del più alto livello archeologico accertato della serie. le testimonianze archeologiche insistono lungo buona parte delle pareti della trincea dove si osservano aree ad elevata densità di vestigia (concentrazioni di manufatti, lenti carboniose, resti di fauna e frammenti di ocra) alternate ad altre quasi del tutto prive di testimonianze. i resti presentano la massima concentrazione all’interno del paleosuolo, con un progressivo diradamento nei due livelli dell’unità c. in particolare, a circa dieci centimetri di profondità dal top del paleosuolo il materiale archeologico si presenta concentrato e ben organizzato in un singolo livello centimetrico, all’interno del quale i reperti giacciono con gli assi maggiori paralleli alle superfici di strato. una simile distribuzione dei resti caratterizza anche i due livelli archeologici dell’unità c dove si osservano distinti e sottili orizzonti ricchi di materiale separati da livelli limosi completamente sterili (particolare in fig. 2). tab. 1 misure 14c ed età calibrate dei campioni prelevati lungo la sequenza di fonte delle mattinate (nell’ultima colonna a destra sono riportati gli episodi climatici groenlandesi secondo la cronologia della carota gisp2 [meese et al., 1997]). le misure sono state effettuate su diversi tipi di materiali: carboni antropogenici (b3-27, c3-27 e fdm1); limi associati a carboni antropogenici (fdm3); paleosuolo (orizzonte a, fdm2); livelli limosi (col1 e fdm4); sedimenti colluviali (fdm5). i campioni sono stati analizzati dal scottish universities research and reactor centre (uk) (fdm2, 3, 4 e 5), beta analitic inc. (usa) (fdm1 e col1) e dal laboratorio di datazioni del dipartimento di fisica dell'università di roma “la sapienza” (b3-27 e c3-27). le datazioni più recenti di ca. 20 14c ka b.p. sono state calibrate con il programma calib rev4.4 (database intacal98 [stuiver et al. 1998]). per le misure maggiori di 20 ka è stata invece ottenuta una stima di calibrazione utilizzando i dati riportati in hughen et al (2004) e beck et al. (2002). 14c and calibrated ages of the samples collected at the fonte delle mattinate sequence (the right column reports the greenland climatic events according to the gisp2 time-scale [meese et al., 1997]). the measurements are related to different materials: anthropogenic charcoal (b3-27, c3-27 e fdm1); silt with anthropogenic charcoal (fdm3); paleosol (horizon a, fdm2); silty layers (col1 and fdm4); colluvial deposits (fdm5). the samples were analysed by scottish universities research and reactor centre (uk) (fdm2, 3, 4 e 5), beta analitic inc. (usa) (fdm1 e col1) and by dating laboratory of the dipartimento di fisica dell'università di roma “la sapienza” (italy) (b3-27 e c3-27). the dates younger than ca. 20 14c ka b.p. were calibrate by using the software calib rev4.4 (intacal98 database [stuiver et al. 1998]). the dates older than 20 ka have been calibrated by using the data reported in hughen et al (2004) e beck et al. (2002). camp. unità materiale cod. lab. tecnica età 14c 2σσ età cal (ka bp) greenland fdm5 f colluvio gu-9428 rad. 4970b 70 5773-5594 / 5891-5782+ fdm4 top d silt organico gu-9427 rad. 18.840b 140 23,161-21,611+ g12 col1 top c silt organico rad. 24.150b 120 ~29-27,5*; 29,5-28,5# he3-g14 fdm3 base c silt con carboni gu-9426 rad. 25.930b 330 ~30,5-29*; 31-30# he3 c3-27 top b carbone rad. 28.300a 790 ~34-30,5*; 35,5-32# g17-g15a fdm2 top b paleosuolo gu-9425 rad. 28.910b 390 ~34,5-32*; 35,5-32,5# g17-g15 fdm1 top b carbone beta-185354 ams 30.940b 310 ~36-34,5*; 38-37# g18-g17 b3-27 top b carbone rad. 31.510a 860 ~37-35*; 39,5-38# he4-g17 b. giaccio et al. 237 fig. 4 vista generale e alcuni particolari di una delle aree ad elevata concentrazione di resti culturali al top del paleosuolo (unità b) esplorata nel corso di uno scavo di emergenza. general view and details of one of the areas with high density remains at top of the paleosol (unit b) explored in during an emergence excavation. la risposta ambientale ed umana ... i dati emersi nel corso di un scavo di emergenza, che ha interessato una limitata porzione della superficie del sito, hanno inoltre evidenziato che il livello al top del paleosuolo costituisce un livello di occupazione umana con abbondanti manufatti litici, rari reperti faunistici, frammenti di ocra, carboni ed alcuni massi calcarei decimetrici del tutto isolati nel deposito limoso (fig. 4). indizi forniti sia dalle caratteristiche morfometriche di questi ultimi sia dal contesto sedimentologico del deposito, suggerirebbero che tali elementi siano di apporto antropico. in particolare, il refitting di un nucleo indica che la superficie indagata rappresenta un’area di lavorazione relativa ad un ben distinto episodio di frequentazione umana in condizioni di giacitura primaria pressoché indisturbate (fig. 5). nel loro complesso, questi elementi indicherebbero la probabile presenza di strutture e una certa organizzazione spaziale nell’uso dell’area di fdm (cfr. silvestrini et al., in stampa). sensibilmente diversa è la giacitura dei reperti negli orizzonti più profondi del paleosuolo dove il materiale appare privo di una precisa organizzazione stratigrafica e decisamente disperso fino alla profondità di oltre un metro. sul piano tafonomico, questa marcata differenza può essere verosimilmente addebitata ad un disturbo post-deposizionale legato ai particolari processi pedogenetici propri dei vertisuoli (contrazioni e dilatazioni della componente argillosa con continua dislocazione dei materiali). in termini di processi di formazione del sito, la coesistenza dei resti archeologici indisturbati con quelli coinvolti nei processi vertici implicherebbe che la frequentazione umana sia iniziata nelle fasi di piena attività della pedogenesi e sia perdurata fino al seppellimento del suolo. più precisamente, a partire dai primi momenti di occupazione umana, databili ad almeno 31.510±860 14c anni b.p. (tab. 1), il successivo alternarsi di episodi di frequentazione e di aggradazione dell’unità b, nonché la continuità dei processi pedogenetici in atto, ha determinato la formazione dell’orizzonte archeologico caratterizzato da drastici disturbi postdeposizionali. nel periodo compreso fra 28.910±390/28.300±790 e 25.930±325 14c anni b.p., che ha visto i primi impulsi della sedimentazione alluvionale dell’unità c e gli ultimi episodi di frequentazione umana, si determina invece il seppellimento del suolo con il conseguente arresto dei movimenti vertici e preservazione dei resti archeologici in livelli di occupazione ben distinti e separati da sedimenti sterili. considerando un simile quadro dei processi di formazione del sito, le datazioni delle lenti carboniose al top del paleosuolo (tab. 1) indicherebbero solo l’età minima dell’inizio della frequentazione umana a fdm, che quindi è verosimilmente più antica di 31.510±860 14c anni b.p. 4.2. osservazioni sui manufatti litici e la fauna in generale i manufatti litici mostrano un discreto stato di conservazione. le superfici si presentano infatti prive di abrasioni e corrosione, quasi del tutto assenti sono pure le sbrecciature postdeposizionali, anche su reperti laminari con margini taglienti estremamente sottili e fragili. molto frequenti sono invece le frammentazioni dei prodotti della scheggiatura, siano esse intenzionali o di origine postdeposizionale. sebbene l’esiguità del numero dei pezzi integri non permetta soddisfacenti analisi tipometriche, e quindi precise caratterizzazioni dei tre livelli antropici, alcune differenze negli indici d’allungamento si possono tuttavia notare. il materiale al top del paleosuolo (unità b) si distingue infatti per prodotti tendenzialmente meno laminari rispetto a quelli presenti alla base dell’unità c, mentre l’indice di carenaggio risulta concorde nei tre livelli. sotto il profilo tecnologico-tipologico i reperti si caratterizzano per l’abbondanza di prodotti di scheggiatura grezzi (con margini non modificati debitage) fortemente laminari, associati a schegge spesse ampiamente ricoperte da cortice. molto rari i reperti diagnostici (fig. 6) tra i quali si segnalano: una piccola lama denticolata (d1, secondo la nomenclatura di laplace, 1964), un doppio incavo (d1), un raschiatoio denticolato (d2), una punta denticolata (d3), un raschiatoio denticolato carenoide (d6), un grattatoio (g1), un grattatoio con incavo (g2), un raschiatoio marginale (r1), un raschiatoio su lama (r2), un bulino (b1), due microlamelle a dorso (ld1) inquadrabili nella variante lamella dufour, due lame a dorso (ld1 ld2), una punta a dorso (pd4) inquadrabile nel sottotipo microgravette, una troncatura marginale (t1), una troncatura semplice (t1), una troncatura obliqua (t3), un becco (bc2), una lama a ritocco 238 fig. 5 particolare della paleosuperficie illustrata in figura 4. le frecce indicano i prodotti di scheggiatura rimontati nel nucleo raffigurato in basso. details of the paleosurface of figure 4. the arrows indicate the flakes refitted in the core of the lower panel. b. giaccio et al. denticolato (l2). nel complesso tale associazione suggerisce, in accordo con i dati cronometrici (tab. 1), un ambito culturale del paleolitico superiore antico (early upper palaeolithic come definito da gamble, 1999), ascrivibile, secondo silvestrini et al. (in stampa), all’aurignaziano. i resti di fauna sono decisamente scarsi, molto frammentari e generalmente in cattive condizioni di conservazione. lo stato di alterazione è particolarmente avanzato sui reperti rinvenuti nel paleosuolo, dove le ossa si presentano con superfici corrose, struttura disaggregata e in alcuni casi quasi completamente dissolte dai processi pedochimici. fra i rari reperti determinabili, tutti rinvenuti nel paleosuolo, si segnalano: un frammento di ramo orizzontale di mandibola dx con molari di bos primigenius (aurochs); un molare (3 super. dx) di equus ferus cf germanicus (cavallo selvatico) (f. fedele, com. pers.) e alcuni denti di cervidae. 5. correlazione con alcuni record paleoambientali regionali e super-regionali le successioni tardopleistoceniche di ambiente alluvionale e di versante dell’appennino centrale sono caratterizzate da alternanze di depositi ghiaioso-sabbiosi e di livelli pedogenizzati (es. frezzotti & giraudi, 1992; giraudi & frezzotti; 1997; miccadei et al., 1998). fra questi ultimi si distingue un caratteristico paleosuolo sviluppato su ceneri vulcaniche correlate all’ignimbrite campana che costituisce un importante marker stratigrafico di un’ampia area dell’appennino centrale (frezzotti & narcisi, 1996; giraudi & frezzotti, 1997). le numerose datazioni radiocarbonio disponibili per questo pedomarker (fig. 7) definiscono un picco di massima frequenza compreso tra 32.000 e 30.000 14c anni b.p. (frezzotti & narcisi, 1996, cum biblio; giraudi 239 fig. 6 alcuni reperti selezionati dal sito di fonte delle mattinate: 1-2 punta e lamella (dufour) a dorso marginale; 3 punta a dorso (microgravette); 4-5 bulini; 6 bulino/grattatoio; 7 grattatoio carenato; 8-9 troncature; 10-11 coltelli a dorso; 12-19 lame e lamelle grezze. some selected lithics from fonte delle mattinate site: 1-2 point bladelet (dufour) and bladelet (dufour) point with marginally backed; 3 backed point (microgravette); 4-5 burins; 6 burin/endscraper; 7 carinate endscraper ; 10-11 back-knife; 12-19 unretouched blades and bladelets. la risposta ambientale ed umana ... & mussi 1999, cum biblio; moro et al., 2002, cum biblio) perfettamente compatibile con l’età del paleosuolo di fdm (tab. 1). la correlazione tra il pedomarker e il paleosuolo di fdm è ulteriormente corroborata da forti analogie stratigrafiche che legano la successione di fdm a quelle appenniniche contenenti il pedomarker. molte fra queste successioni mostrano infatti la stessa sequenza di fdm costituita dal pedomarker sepolto da sedimenti ghiaiosi la cui associazione di facies è compatibile con conoidi alluvionali (giraudi & frezzotti, 1997; giaccio et al. 2004b). lo sviluppo di un sistema deposizionale di conoide alluvionale (unità c) a fdm corrisponde dunque ad un fenomeno che ha interessato ampi settori dell’appennino centrale. i prodotti dell’eruzione dell’ignimbrite campana (ic), costituenti il parent material del pedomarker appenninico, sono stati identificati nella sequenza pollinica del lago grande di monticchio (narcisi, 1996), nella carota tirrenica ket 8003 (ton-that et al., 2001) e, come segnale vulcanogenico, nella stratigrafia isotopica groenlandese (fedele et al., 2003) esattamente in corrispondenza dell’inizio dell’heinrich event 4 (he4). i dati radiocarbonio disponibili e la peculiare posizione paleoclimatica dell’ic permettono di identificare, nell’ambito di questi importanti record, la fase climatica in cui si instaurarono le condizioni ottimali per lo sviluppo del pedomarker appenninico e quindi del coevo paleosuolo di fdm. questa corrisponde alla zona pollinica 5b della sequenza di monticchio (es. allen et al., 1999) e alle prime fasi del ciclo di bond (bond et al., 1993; bond & lotti, 1995) che segue con il brusco riscaldamento del greenland interstadial 8 (gi8, sensu walker et al., 1999) la fine dell’he4 (fig. 7). questa correlazione è supportata dalle seguenti osservazioni stratigrafiche e cronometriche: i) il gi8 e la zona pollinica di monticchio 5b (mpz5b) coincidono con il primo sensibile aumento della temperatura ed umidità dopo la deposizione del parent material del pedomarker (ic) e quindi la prima fase favorevole alla pedogenesi; ii) il gi8 e la mpz5b rappresentano rispettivamente l’ultimo ben marcato e prolungato interstadiale e l’ultimo episodio di notevole abbondanza di taxa arborei dell’ultimo glaciale, ovvero l’ultima fase climatica dell’ultimo glaciale compatibile con lo sviluppo di un diffuso e profondo suolo; iii) secondo allen & huntley (2000) e dasgaard et al. (1993) la mpz5b e il gi8 sono correlati all’interstadio di denekamp che nell’europa temperata è rappresentato da un diffuso paleosuolo sviluppatosi nell’intervallo 32.000-28.000 14c anni b.p. (bhere, 1989) coevo quindi al pedomarker e al paleosuolo di fdm; iv) la calibrazione stimata delle misure 14c (beck et al., 2001; hughen et al., 2004) disponibili per il pedomarker definisce un intervallo di massima frequenza di ca. 38-35 cal ka b.p., un periodo che comprende il gi8 e 7 (fig. 7). avvalendosi di tale correlazione e considerando le datazioni radiocarbonio disponibili (tab. 1), è possibile avanzare alcune ipotesi sul significato paleoambientale di altre unità stratigrafiche di fdm, alla luce del dettagliato quadro paleoclimatico e cronologico fornito dal record groenlandese e di monticchio. l’unità alluvionale c, che determina il seppellimento del paleosuolo al tetto dell’unità b, rappresenta la risposta morfologico-sedimentaria di una fase resistatica che segue le precedenti condizioni biostatiche di cui il paleosuolo è chiara espressione. i dati radiocarbonici di fdm indicherebbero che questa modificazione geoambientale, corrispondente alla più importante fase di sviluppo della conoide alluvionale (unità c, figg. 2 e 3), si verificò tra 26 e 24 14c ka b.p. (tab. 1, figg. 2 e 3), un intervallo che secondo numerosi record marini coinciderebbe con l’he3 di (bond et al., 1993; bond & lotti, 1995; cortijo et al., 1997; cacho et al., 1999; thouveny et al., 2000). pur considerando le incertezze cronologiche relative alla differenza tra età radiocarbonio marina e atmosferica, questa fase di peggioramento climatico può essere verosimilmente correlata all’he3. i dati attualmente disponibili sulle fluttuazioni del 14c atmosferico (beck et al., 2001; hughen et al., 2004) permettono infatti di ottenere una stima di calibrazione delle misure radiocarbonio della base e del tetto dell’unità c congruenti con l’età di questo evento (tab. 1; fig. 7). in termini stratigrafici, l’he3 rappresenta inoltre la fase stadiale più acuta dopo la formazione del paleosuolo correlato al gi8-6 (fig. 7) e quindi, anche sul piano paleoclimatico, un episodio perfettamente compatibile con le modificazioni ambientali documentate a fdm da un’importante fase alluvionale. in sintesi, i dati stratigrafici e cronologici di fdm indicherebbero che la successione comprendente le unità a-b-c sia ascrivibile all’intero ciclo di raffreddamento millenario (bond cycle) verificatosi tra il gi8 e l’he3 (ca. 38-29 gisp2 ka b.p.; fig. 7). la fase di impostazione del lago di colfiorito, o di innalzamento del suo livello, che segue l’he3 (<24.150±120 e >18.480±140 14c anni b.p.) è correlabile all’alto stazionamento lacustre dell’ultimo massimo glaciale, ben documentato nell’appennino abruzzese (es. giraudi & frezzotti, 1997) e in altre regioni del mediterraneo (prentice et al., 1992). in particolare, nel caso del bacino di colfiorito, l’espansione dello specchio lacustre può essere stata favorita sia dalle generali condizioni idrologiche dell’ultimo massimo glaciale caratterizzate da un bassissimo tasso di evapotraspirazione tale da compensare le scarse precipitazioni di questo periodo (prentice et al., 1992) sia da una probabile ostruzione degli inghiottitoi carsici favorita all’aumento degli apporti detritici grossolani. anche in questa fase di massimo livello lacustre, l’area del sito di fdm conobbe tuttavia solo periodici episodi di completa sommersione alternati a momenti di emersione caratterizzati dalla formazione di un emissario. il successivo periodo che vede il ristabilirsi di condizioni di stabilità, favorevoli allo sviluppo di un suolo intorno ai 18 14c ka b.p., potrebbe invece correlarsi al fornaca interstade: una fase climatica mite che ha interessato l’appennino centrale dopo la massima avanzata dei ghiacciai abruzzesi (giraudi & frezzotti, 1997). questa fase potrebbe corrispondere al gi2 nonché a uno dei picchi di maggiore abbondanza di arboree della zona pollinica 4 di monticchio (fig. 7). l’ultimo episodio di sedimentazione alluvionale (unità d) è difficilmente ascrivibile ad una fase climatica ben definita per l’ampia forchetta cronologica che lo delimita (<18.480±140 e >4970±70 14c anni b.p.). esso tuttavia potrebbe corrispondere alla fase di sedimentazione detritica documentata in italia centrale durante he1 (giraudi, 1996) 240 b. giaccio et al. 241 f ig . 7 c o rr e la zi o n e d e lla s e q u e n za d i f o n te d e lle m a tt in a te ( f d m ) c o n a lt re s u c c e ss io n i su b a e re e ( p e d o m a rk e r) e l a c u st ri ( m o n ti c c h io ; a l l e n e t al ., 1 9 9 9 ; 2 0 0 0 ) d e ll’ a p p e n n in o c e n tr o -m e ri d io n a le e c o n u n r e c o rd p a le o a tm o sf e ri c o g ro e n la n d e se ( g is p 2 ; m a y e w s k i e t al ., 1 9 9 7 ). p o si zi o n e d e g li h e in ri c h e ve n ts ( h s) n e lla s e q u e n za d i m o n ti c c h io e d e ll’ ig n im b ri te c a m p a n a ( ic ) n e lla c a ro ta g is p 2 r is p e tt iv a m e n te s e c o n d o w a t t s e t al . (1 9 9 6 ) e f e d e l e e t al . (2 0 0 3 ). c a lib ra zi o n e s ti m a ta d e lle e tà > 2 0 .0 0 0 1 4 c a n n i b .p . 1 4 c d i f d m ( t a b . 1 ) e d e l p a le o su o lo s vi lu p p a to s u c e n e ri d e ll’ ic ( p e d o m a rk e r: 2 9 .0 9 0 ± 3 5 0 ; 2 9 .6 9 0 ± 1 1 1 0 ; 3 0 .1 1 0 ± 3 1 0 ; 3 1 .2 2 0 ± 1 4 0 0 ; 3 1 .5 0 0 ± 5 0 0 ; 3 2 .5 1 0 ± 1 6 0 0 ; 3 3 .1 4 0 ± 1 4 0 0 ; 3 8 .7 7 0 ± 2 1 7 0 ) se c o n d o h u g h e n e t al . (2 0 0 4 ) o , se < 2 0 .0 0 0 1 4 c a n n i b .p ., s t u iv e r e t al . (1 9 9 8 ). s i n o ti c h e l e s ti m e d i c a lib ra zi o n e s e c o n d o b e c k e t al . (2 0 0 1 ) q u i n o n r ip o rt a te p e r u n a m a g g io re c h ia re zz a g ra fic a d e fin is c o n o u n q u a d ro c ro n o lo g ic o d i u n o o d u e m ill e n n i p iù a n ti c o ( t a b . 1 ), m a a n c o ra c o m p a ti b ile , se n o n a d d ir it tu ra p iù c o n g ru e n te , c o n la c o rr e la zi o n e p ro p o st a . c o rr e la ti o n o f th e f o n te d e lle m at ti n at e s e q u e n c e w it h o th e r su b ae ri al ( p e d o m ar ke r) a n d l ak e ( m o n ti c c h io ; a l l e n e t a l., 1 9 9 9 ; 2 0 0 0 ) su c c e ss io n s o f th e c e n tr al -s o u th e rn a p e n n in e s an d w it h a g re e n la n d p al ae o at m o sp h e ri c r e c o rd ( g is p 2 ; m a y e w s k i e t a l., 1 9 9 7 ). p o si ti o n o f th e h e in ri c h e ve n ts ( h s) i n t h e m o n ti c c h io s e q u e n c e a n d o f th e c am p an ia n i g n im b ri te i n t h e g is p 2 c o re ac c o rd in g t o w a t t s e t a l. (1 9 9 6 ) an d f e d e l e e t a l. (2 0 0 3 ), r e sp e c ti ve ly . e st im at e c c al ib ra ti o n o f th e 1 4 c a g e s o f f d m > 2 0 ,0 0 0 1 4 c y e ar s b .p . o f f d m ( t ab . 1 ) an d o f th e p al e o so l(s ) d e ve lo p e d o n c i as h ( p e d o m ar ke r: 2 9 ,0 9 0 ± 3 5 0 ; 2 9 ,6 9 0 ± 1 1 1 0 ; 3 0 ,1 1 0 ± 3 1 0 ; 3 1 ,2 2 0 ± 1 4 0 0 ; 3 1 ,5 0 0 ± 5 0 0 ; 3 2 ,5 1 0 ± 1 6 0 0 ; 3 3 ,1 4 0 ± 1 4 0 0 ; 3 8 ,7 7 0 ± 2 1 7 0 ) ac c o rd in g t o h u g h e n e t a l. (2 0 0 4 ) o r s t u iv e r e t a l. (1 9 9 8 ). n o te t h at a c c o rd in g t o t h e b e c k e t a l. (2 0 0 1 ) d at ac al ib ra ti o n s, w h ic h a re n o t re p o rt e d h e re , th e c h ro n o lo g ic al f ra m e w o rk s h o u ld b e o n e o r tw o m ill e n n ia l o ld e r, b u t st ill c o n si st e n t, o r e ve n m o re su it ab le , w it h t h e p ro p o se d c o rr e la ti o n . la risposta ambientale ed umana ... 6. ciclicità climatica dell’ois3, modificazioni ambientali e discontinuità archeologiche: alcune considerazioni preliminari sul sito di fdm e sul contesto mediterraneo le tracce materiali ed il contesto tafonomico-stratigrafico della successione indagata indicano che il giacimento di fonte delle mattinate rappresenti un sito primario coincidente con un’area di frequentazione umana ai margini di un canale fluviale, soggetta a pedogenesi e a periodici episodi di inondazione. le caratteristiche e la configurazione spaziale dei resti culturali, con aree ad elevata densità di vestigia dislocate in diversi punti di un’ampia superficie, sono compatibili con brevi ma ripetute e non occasionali occupazioni umane. i dati cronologici e stratigrafici disponibili indicano infatti che l’area del sito fu periodicamente frequentata, probabilmente in maniera sistematica, per almeno sei millenni (ca. 32-26 14c ka b.p.), con i primi episodi di occupazione anteriori a 31.510±860 14c anni b.p. in termini paleoambientali, i dati lito-pedostratigrafici indicherebbero condizioni di marcata stabilità favorevoli allo sviluppo di un suolo profondo durante i primi 4-5 millenni della frequentazione. i successivi millenni di frequentazione vedono l’inizio di una certa instabilità ambientale testimoniata dai primi impulsi di sedimentazione alluvionale dell’unità c (fig. 8). sulla base della correlazione proposta (fig. 7), la fase di frequentazione corrisponderebbe all’intervallo compreso tra il gi8 e l’inizio dell’he3 (almeno 37-30 gisp2 ka b.p.); un periodo caratterizzato dalla rapida successione di quattro marcate oscillazioni di d/o (fig. 7). ciò implicherebbe che le quattro fasi stadiali occorse nel periodo che precede all’he3 non abbiano avuto significativi effetti né sull’ambiente, la cui stabilità è interrotta solo da alcuni sporadici episodi alluvionali, né sui gruppi umani che non sembrano interrompere la frequentazione a fdm (fig. 7). queste evidenze sono in accordo con recenti studi di sequenze mediterranee che indicano moderate variazioni climatico-ambientali associate alle fasi stadiali dei cicli di d/o non connessi agli hes (es. cacho et al., 1999; sánchez goñi et al., 2000). questo lungo periodo di periodiche occupazioni umane testimonia una notevole importanza dell’area di fdm per i gruppi umani paleolitici. ciò può essere addebitato a diversi fattori geografici ed ecologici. una prima osservazione può essere avanzata nei riguardi del potenziale carattere strategico dell’area che cade sullo spartiacque appenninico, lungo una delle principali vie che in questo settore della catena consentono un’agevole comunicazione fra versante adriatico e tirrenico. è verosimile che questo corridoio naturale rappresentò una via preferenziale sia per le reti di comunicazione umana che per i movimenti migratori stagionali dei grandi erbivori. altri elementi che probabilmente hanno influenzato la frequentazione paleolitica, sono rappresentati dalla presenza di un corso d’acqua e di un probabile specchio lacustre. entrambi hanno costituito infatti aree preferenziali per gli insediamenti e le frequentazioni di gruppi umani del paleolitico superiore in diversi contesti geografici dell’europa continentale (gribchenko & kurenkova, 1997; bocquet-appel & demars, 2000; chlachula, 2001). questo millenario interesse dei cacciatori raccoglitori sembra interrompersi in coincidenza con un significativo mutamento ambientale connesso all’episodio di marcato raffreddamento dell’he3. le evidenze stratigrafiche di fdm indicano infatti un radicale cambiamento sia del contesto archeologico (totale scomparsa di qualsiasi traccia di presenza umana) sia del quadro ambientale che registra la più significativa fase di sedimentazione alluvionale (fig. 8). in effetti, la sterilità archeologica dei livelli siltosi, presenti nell’unità c e nelle altre unità che seguono verso l’alto, può essere spiegata sia come evidenza di un’effettiva interruzione della frequentazione umana sia come semplice dislocazione della località di stazionamento. entrambi gli scenari, sia pure con gradi e significati molto diversi tra loro, indicano comunque una certa discontinuità coincidente con l’he3 compatibile sia con un totale abbandono dell’area, sia con cambiamenti meno drastici che potrebbero aver coinvolto aspetti inerenti la frequenza, la durata e la localizzazione delle occupazioni, nonché l’entità numerica dei gruppi paleolitici e il tipo di attività svolta a fdm. i dati paleoambientali di monticchio (es. watts et al., 2000) indicano che in appennino meridionale l’he3 coincise con una brusca contrazione delle foreste che lasciarono il posto ad ampi spazi aperti di steppa arida e fredda dominate da artemisia e chenopodiaceae (allen et al., 2000; fig. 7). in termini paleoecologici umani, le basse temperature e l’estrema aridità associate all’he3 non costituiscono per sé stesse significativi fattori limitanti (cfr. vrba et al., 1995). ciò che invece può rivestire un certo significato è l’eccezionale rapidità con la quale si instaurarono tali condizioni ambientali. nel breve periodo di poche generazioni, forse anche una o due secondo i tempi del cambiamento climatico indicati dal record paleoatmosferico groenlandese (es. mayewski et al., 1997; fig. 7), i gruppi umani si trovarono infatti a fronteggiare un ecosistema radicalmente mutato, sia nella distribuzione dei biomi vegetali ed animali che nel pattern della rete idrica. un simile rapido cambiamento probabilmente si inserì nelle dinamiche dei processi interattivi uomo-ambiente come un poderoso agente, in grado di innescare profondi cambiamenti nei comportamenti e nelle strategie di sussistenza. verosimilmente questi processi agirono in modo particolarmente efficace proprio nelle aree simili a quella di fdm, più interne ed elevate dell’appennino centrale e quindi più sensibili e reattive alle modificazioni climatiche. il risultati emersi dai dati di fdm trovano nell’attuale panorama delle ricerche nazionali e internazionali poche altre evidenze di significative discontinuità archeologiche chiaramente connesse alla ciclicità climatica ad alta frequenza dell’ois3, e più in particolare rispetto ai drastici episodi di raffreddamento e inaridimento degli hes. ad esempio, fedele et al. (2003) hanno recentemente evidenziato una netta discontinuità nel record archeologico dell’italia meridionale e di altre regioni dell’europa sudorientale coincidente con l’he4. in quest’ampia area, l’he4 marca infatti un diffuso abbandono di siti, con una probabile importante dislocazione territoriale dei gruppi umani, nonché segna una netta cesura fra i tecnocomplessi dell’earliest upper palaeolithic e i successivi gruppi di industrie dell’early upper palaeolithic (entrambi i termini sensu 242 b. giaccio et al. 243 fig. 8 ricostruzione delle principali tappe dell'evoluzione ambientale e dell'occupazione umana al sito di fonte delle mattinate nel corso dell'intervallo di 32-18 14c ka b.p. o 38-23 cal ka b.p. reconstruction of the main phases of both environmental evolution and human occupation at fonte delle mattinate site during the 3218 14c or 38-23 cal ka b.p. interval. la risposta ambientale ed umana ... gamble, 1999). alcuni autori (es. kozlowski, 1990; gamble, 1999) vedono in questo passaggio un’importante rottura del record archeologico europeo, caratterizzata dalla definitiva scomparsa di una serie di comportamenti radicati nei millenni e la comparsa di nuovi tratti culturali. secondo fedele et al. (2003), queste importanti discontinuità non sono tuttavia connesse esclusivamente ad un possibile impatto dell’he4, quanto piuttosto ad una profonda e vasta crisi ecologica generata dalla sovrapposizione e muta amplificazione degli effetti della catastrofica eruzione dell’ignimbrite campana e dell’he4 (cfr. sinitsyn, 2003). su una base dati e con un approccio completamente diversi, d’errico & sánchez goñi (2003) hanno analogamente riconosciuto nella penisola iberica una significativa discontinuità coincidente con l’he4, che, secondo gli autori, coinvolse sia la sfera culturale (passaggio paleolitico medio/superiore) quanto quella biologica (scomparsa dei neandertal e arrivo dei gruppi umani di anatomia moderna). in questo caso, tuttavia, il quadro proposto appare molto fragile e decisamente discutibile (cfr. finlayson et al., 2004, per una critica su altri aspetti). d’errico & sánchez goñi (2003) tracciano infatti le loro conclusioni comparando per semplice via cronometrica trascurando cioè ogni evidenza stratigrafica dei singoli contesti archeologici il quadro culturale con un record pollinico del mare di alboran; il primo basato su datazioni 14c mentre il secondo su un modello cronologico completamente diverso. al fine di comparare i due gruppi di dati gli autori convertono la scala temporale del record pollinico in anni 14c assumendo che l’età atmosferica dell’inizio dell’he4 sia di 35.000 anni radiocarbonio, cioè la stessa di quella oceanica delle alte latitudini. è noto tuttavia che le differenze fra età marina e atmosferica dell’he4, il così detto marine reservoir age effect, sia tutt’altro che trascurabile, ed è molto probabile che questo raggiunse alle alte latitudini valori superiori a 2000 anni (es. voelker et al., 1998; 2000, cum biblio). recenti studi hanno inoltre evidenziato che in stretta coincidenza temporale con l’he4 si verificò un marcato aumento del flusso di elementi cosmogenici come 10be, 36cl e 14c (es. voelker et al., 2000; wagner et al., 2000; beer et al., 2002). in termini cronometrici, l’elevato flusso di 14c si traduce in marcate distorsioni della scala del radiocarbonio (forti ringiovanimenti, inversioni, dilatazioni e compressioni temporali) con inevitabili ripercussioni sull’interpretazione cronologica delle serie abbraccianti l’he4. ad esempio, voelker et al. (2000) hanno dimostrato che nel mare del nord, sebbene l’he4 sia effettivamente datato a ca. 35 14c ka b.p., i sedimenti di 1000-2000 anni più antichi dell’he4 hanno restituito età radiocarbonio di ca. 32 ka. in ambiente continentale, è stato inoltre constatato (fedele et al., 2003) che in tutte le sequenze archeologiche contenenti l’ignimbrite campana, dall’italia meridionale all’ucraina, l’età media dei livelli immediatamente ricoperti dal tefra, e quindi più antichi dell’he4 (fig. 7), è di soli 33.000-31.000 anni 14c b.p. queste concrete evidenze stratigrafiche rendono poco appropriata la semplice comparazione cronometrica di dati culturali e paleoambientali adottata da d’errico & sánchez goñi (2003), e dunque minano alla base le ipotesi e le conclusioni proposte dagli autori. altrettanto semplicistica appare l’asserita correlazione tra industrie del paleolitico medio e neandertal, da un lato, e tra complessi del paleolitico superiore e uomini di anatomia moderna, dall’altro. al momento infatti, per le fasi più antiche del paleolitico superiore precedenti a ca. 33-32 14c ka b.p. (earliest upper palaeolithic di gamble [1999] o initial upper palaeolithic di bar-yosef & pilbeam [2000]) i resti fossili umani sono rarissimi, frammentari e di dubbia classificazione (cfr. churchill & smith, 2000; trinkaus et al., 2003). non mancano inoltre casi di probabili associazioni tra resti di neandertal e industrie del paleolitico superiore antico (es. ahern et al., 2004). il quadro delle conoscenze in questo ambito appare dunque ancora largamente frammentario e in parte pesantemente condizionato dai limiti e da un uso disinvolto della scala del radiocarbonio. è più che ovvio inoltre che i fattori climatico-ambientali costituiscono solo una parte degli attori in gioco nei processi di cambiamento dei sistemi culturali paleolitici. ogni generalizzazione sul problema delle discontinuità archeologiche formulata alla luce dei soli eventi climatico-ambientali, sia pure in relazione alle estreme condizioni associate agli hes, risulterebbe quindi prematura e inevitabilmente semplicistica. è tutt’altro che improbabile tuttavia, come le evidenze di fdm sembrerebbero suggerire, che i rapidi e drastici cambiamenti associati agli hes abbiano in qualche modo alterato gli equilibri del rapporto uomoambiente, destabilizzando adattamenti e strategie consolidate in secoli o millenni di conoscenza e prevedibilità dei sistemi ambientali. conclusioni lo studio combinato stratigrafico e archeologico della sequenza di fonte delle mattinate (fdm) ha mostrato una chiara relazione tra processi geo-ambientali e occupazione umana entrambi condizionati dalle principali fasi interstadiali e stadiali dell’ultimo ciclo di bond dell’ois3 (ca. 38-29 gisp2 ka b.p.). il record geologico indica condizioni di notevole stabilità ambientale nella fase iniziale del ciclo bond (gi8-6; ca. 38-33 gisp2 ka b.p.) durante la quale a fdm e in un ampio settore dell’appennino centrale si sviluppa un profondo suolo. tra il gi6 e il gi5, il record di fdm registra invece alcuni eventi alluvionali e l’arresto della pedogenesi; primi sporadici impulsi di una sedimentazione alluvionale che ha la sua più importante fase di sviluppo nel corso dell’heinrich event 3 (he3), l’episodio conclusivo di estremo raffreddamento che chiude l’ultimo ciclo di bond dell’ois3. contrariamente al record isotopico groenlandese, ma in accordo con altri indicatori climatici di questa regione e dell’area mediterranea, queste evidenze indicherebbero che gli hes in italia centrale furono caratterizzati da condizioni climatiche freddo-aride e modificazioni ambientali molto più marcate di quelle associate alle altre fasi stadiali dei cicli di d/o. le tracce culturali di fdm indicano che durante tutto il periodo precedente all’he3 (ca. 38-30 gisp2 ka b.p.) il settore nord-orientale della piana di colfiorito fu sede di brevi soste di gruppi umani fasi del paleolitico superiore antico (aurignaziano), probabilmente nell’ambito di spostamenti stagionali lungo una delle principali 244 b. giaccio et al. vie naturali che, attraverso l’area di fdm, connette il versante tirrenico a quello adriatico. la scomparsa delle tracce archeologiche, a partire dall’inizio dell’he3, indicherebbe un significativo cambiamento nella localizzazione delle occupazioni nella piana di colfiorito o addirittura una definitiva interruzione della millenaria frequentazione di questa area strategica sullo spartiacque appenninico. ciò suggerirebbe che durante l’ois3, le modificazioni geo-ambientali associate agli hes condizionarono sensibilmente le strategie insediative dei gruppi paleolitici, probabilmente limitando o modificando la mobilità nelle aree montane più interne dell’appennino centrale. nel panorama delle ricerche in corso in questo ambito, le evidenze di fdm si inseriscono in un mosaico ancora nebuloso e in parte condizionato da approcci e modelli semplicistici, ma che nel complesso sembrerebbe indicare gli hes come potenziali importanti agenti nelle dinamiche interattive uomo-ambiente del pleistocene recente mediterraneo. ringraziamenti si ringrazia francesco fedele (università di napoli “federico ii) per la determinazione della fauna e le utili discussioni sugli aspetti paleoecologici umani. le analisi sedimentologiche hanno beneficiato di preziose osservazioni sul terreno di sabatino ciarcia (università di napoli “federico ii). il lavoro di ricognizione, scavo archeologico e documentazione fotografica è stato condotto con i contributi di fabio grossi, gianluca reddavide, simona rosselli, alessandro spera (università di roma “tor vergata”) e antonio todero (università di bologna). si ringraziano ernesto e luca santucci con i quali alcuni di noi (b.g. e m.r.) hanno piacevolmente condiviso due settimane di scavo e permanenza a fdm. desideriamo infine ringraziare giuseppe chiodi (soprintendenza archeologica delle marche) per il costante supporto fornito nel corso delle indagini sul terreno. bibliografia ahern j.c.m., karavanić i., paunović m., janković i. & smith f.h. 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(it issn 0394-3356, 2004). il f° 471 “irsina” (basilicata) ricade lungo il confine catena-avanfossa, per cui risulta costituito da due porzioni rappresentative di aree molto differenti sia dal punto di vista morfo-strutturale, che stratigrafico. in particolare, nella parte orientale del foglio affiorano depositi quasi esclusivamente quaternari e ricadenti nell’area della fossa bradanica. la parte superiore ed esposta del riempimento di tale bacino di avanfossa è rappresentata da una successione di sedimenti di tipo regressivo, caratterizzata in basso, e per quasi tutto il suo spessore, da emipelagiti siltoso-argillose (formazione delle argille subappennine), e nella parte alta da depositi grossolani che giacciono in contatto transizionale e/o erosivo sulle emipelagiti. il quadro stratigrafico-deposizionale che deriva dai nuovi rilevamenti effettuati nell’area orientale del foglio irsina si differenzia da quanto proposto nella vecchia carta geologica d’italia e nella letteratura prodotta fino agli inizi degli anni ’90: all'interpretazione che proponeva la presenza di una successione di sedimenti costituenti un sistema aggradazionale, nei quali non era precisata la separazione fra sedimenti costieri e continentali, e nei quali la suddivisione formazionale era basata esclusivamente su criteri litologici, si propone ora quella che riconosce un insieme di sedimenti, di età e quote decrescenti da o a e, derivanti da sistemi progradazionali di transizione formatisi alternativamente durante cicli di variazione relativa del livello del mare, cui si sovrappongono, in contatto di discontinuità, depositi continentali. in particolare, alla formazione nota col nome di conglomerato di irsina, che era descritta e cartografata sia come un unico deposito aggradazionale in contatto stratigrafico sulla sottostante formazione indicata col nome sabbie di monte marano, sia come un deposito sincrono dalle aree più interne (600 m s.l.m.) a quelle più esterne (400 m s.l.m.) rispetto alla catena, venivano attribuiti litosomi conglomeratici riconosciuti ora come corpi posti a diversa altezza stratigrafica, di diversa origine ambientale ed, in alcuni casi, in netta discordanza fra loro. il nuovo rilevamento geologico, associato all’analisi di facies, ha infatti permesso di individuare nell’area del f° 471 “irsina”, una successione sabbioso-conglomeratica (indicata col nome formazionale di sabbie e conglomerati di monte s. marco) al cui interno si riconoscono diversi corpi conglomeratici intercalati che possono essere attribuiti a quattro membri posti a quote ed altezze stratigrafiche differenti, e di età progressivamente più giovane da o a e. abstract: sabato l., tropeano m. & pieri p., geological mapping problems regarding quaternary deposits of the f° 471 irsina. the conglomerato di irsina: myth or reality? (it issn 0394-3356, 2004). the area of the f° 471 “irsina”, on scale of 1: 50.000 (carg), is located in basilicata region (southern italy), along the chain-foredeep border of the south-apennines orogenic system. so, the eastern part of the map regards the bradanic trough (foredeep) domain, while the western one regards deformed units of the chain domain. in particular, the eastern part is represented almost by quaternary deposits, more or less in horizontal arrangment, which correspond to the upper part of the in-fill succession of the foredeep basin. the outcropping succession of the basin is represented by regressive deposits characterized below by hemipelagites of the argille subappennine formation, and above by coarse-grained deposits. these latter lie on the hemipelagites of the argille subappennine fm. in, alternatively, conformable or erosional contact. the new geological survey of the f° 471 irsina and the facies analysis carried out on the outcropping deposits, allow us to present a more detailed stratigraphy of the quaternary bradanic trough deposits, in comparison with that one showed by the old geological survey on scale 1:100.000. the upper pliocene-lower pleistocene silty-clays of the argille subappennine fm. are stratigraphically overlain by the sabbie e conglomerati di monte s. marco formation. this formation is made up of lower pleistocene up to 60 m thick sands, sandstones and conglomerates interpreted as offshore-transition to shoreface systems prograding ontoand distally passing tohemipelagites of the argille subappennine fm. several conglomeratic bodies are interbedded in the sabbie e conglomerati di monte s. marco fm., and locally some of them are in erosion on the argille subappennine fm. these bodies have a sigmoidal shape, are clinostratified and show thicknesess variable from some meters to over 60 m. the deposits of these bodies are referred to transitional environments, mostly characterized by deltaic facies; they crop out at different heights above present-day sea level, and their age becomes younger from w to e, from the higher to the lower. according to their stratigraphic position, some of these bodies represent different enter points along the same paleoshoreline; they may be considered coeval and grouped in four members here called: conglomerato di giumentarizzo, conglomerato di madonna della pietà di irsina, conglomerato di monte s. angelo, conglomerato di sant’antonio abate. erosively overlying either the sabbie e conglomerati di monte s. marco fm. or the conglomeratic members, a sandy-conglomeratic deposit is observed. this latter, named sabbie e conglomerati di fosso macello formation, is up to 10 m thick and is related to alluvial environments. the new stratigraphic setting results quite different from that proposed by the previous italian geological cartography on scale of 1:100.000, in which the bradanic trough infill succession was characterized by aggradation of shallow marine and continental deposits. in particular, the conglomerato di irsina formation was described and mapped as a single aggradational deposit overlying the sabbie di monte marano formation, and having the same age from the inner areas (600 m above s.l.) to the outer ones (400 m above s.l.). in the irsina area, where the conglomerato di irsina fm. was established, the new geological survey demonstrates that this deposit is really composed by three conglomeratic lithosomes having different age and different environmental and stratigraphic meaning: a first lithosome is composed of foreshore conglomerates that locally represent the upper part of a regressive sandy succession; the second lithosome is composed of clinobedded deltaic conglomerates erosionally overlying the previous sandy-conglomeratic succession and, distally, the clay deposits; a third lithosome is represented by a continental sandy-conglomeratic deposit erosionally overlying the previous ones. in the old italian geological cartography on scale of 1:100.000 these three lithosomes were represented as one tabular body, aggrading and partially etheropic with the underlying sabbie di monte marano fm. so, the deposits that we now distinguish into three lithosomes (upper part of the sabbie e conglomerati di monte s. marco formation, conglomerato di madonna della il quaternario italian journal of quaternary sciences 17(2/1), 2004, 391-404 392 l. sabato, m. tropeano & p. pieri 1. introduzione nell’ambito del progetto carg, la regione basilicata è stata incaricata di redigere una serie di fogli geologici in scala 1:50.000 ricadenti nell’area regionale. fra questi è compreso il f° 471 “irsina”, che, poiché ricade lungo il confine catena-avanfossa (fig. 1), presenta due porzioni relative ad aree molto differenti fra loro sia dal punto di vista morfo-strutturale, che stratigrafico. nell’area occidentale affiorano unità della catena appenninica, rappresentate da terreni cretacico-terziari derivanti dalla deformazione di un dominio paleogeografico di bacino (bacino di lagonegro esterno evolutosi a bacino irpino) e da depositi plio-pleistocenici di bacini satellite. l’assetto strutturale di tale area è particolarmente complesso, e legato a tettonica polifasica miocenico-quaternaria; in linea generale può essere descritto come un sistema di thrusts e pieghe adriaticovergenti di età neogenico-quaternaria, complicato da strutture trascorrenti e distensive plio-pleistoceniche (sia in direzione appenninica che antiappenninica). nell’area orientale invece affiorano le unità della fossa bradanica, rappresentate per uno spessore di circa 450 m da depositi silicoclastici, quasi esclusivapietà di irsina member and sabbie e conglomerati di fosso macello formation), in the old survey, by mistake, were included only in the conglomerato di irsina formation. also in other localities we observe the occurrence of different conglomeratic lithosomes not distinguished in the old survey. in short, it does not exsist an only conglomeratic and coeval formation on the top of the regressive bradanic succession, so the conglomerato di irsina formation, as established in the sixties and known in the literature, has to be amended. furthermore, the new data demonstrate that the deposits and the upper surface of the bradanic reliefs do not represent an only regressive episode, but a serie of regressive episodes recorded during the tectonic uplift of the bradanic basin. in fact, the stratigraphic organization show a progradational trend rather than an aggradational one. on this subject, the different heights which the regressive deposits outcrop to (from about 600 m a.s.l., up to 400 m a.s.l. in the surveyed area) are not the result of a differential uplifting of the basin after the marine sedimentation, but the recording of the regional uplift occurring during the sedimentation. parole chiave: quaternario cartografia geologica conglomerato di irsina depositi regressivi. keywords: quaternary geological mapping conglomerato di irsina formation regressive deposits. fig. 1 a) principali caratteri strutturali dell’italia; b) quadro geologico schematico dell'italia meridionale; c) distribuzione dei “depositi costieri regressivi” nella zona assiale della fossa bradanica (da pieri et al., 1996); il riquadro indica l’area in cui ricade il f° 471 “irsina”. a) main structural features of italy; b) schematic geological map of southern italy; c) areal distribution of the “depositi costieri regressivi” in the axial part of the bradanic trough (from pieri et al., 1996); the insect shows the location of the f° 471 “irsina”. mente quaternari, con granulometria variabile dal basso verso l’alto da argilloso-siltosa a sabbiosa e/o conglomeratica. tali depositi costituiscono la nota successione della fossa bradanica che si chiude con i termini regressivi (fig. 1, c) oggetto di questa nota. nonostante la pressoché assenza di deformazioni tettoniche, i caratteri stratigrafici di questi depositi si sono rivelati più complessi rispetto a quanto riportato in letteratura, sia per l’estrema variabilità laterale e verticale dei caratteri litologici, sia per la variabilità dei contatti stratigrafici riconosciuti. a queste difficoltà intrinseche si è aggiunta l’esiguità degli studi di dettaglio sedimentologico riferiti in letteratura a tali depositi. il nuovo rilevamento geologico, effettuato in scala 1:25.000 e, in alcuni casi, in scala 1:10.000, associato ad un’accurata analisi di facies, ha permesso, dal punto di vista strettamente cartografico, di distinguere unità differenti rispetto a quelle cartografate nel foglio geologico di riferimento n°188 gravina di puglia (azzaroli et al., 1968a) che, sia per la scala cartografica utilizzata (1:100.000) che per l’assenza di dati stratigrafici e sedimentologici di dettaglio raccolti durante i rilevamenti degli anni ‘60, erano state inglobate in unità formali non più utilizzabili (si vedano le discussioni in: pieri et al., 1996; sabato, 1996) lo scopo di questo lavoro è di presentare il nuovo quadro stratigrafico proposto per le unità regressive della fossa bradanica nell’area del foglio irsina e di contribuire alla discussione inerente i criteri cartografici, relativi ai deposti del quaternario, da utilizzare nella redazione delle nuove carte geologiche. i dati esposti permettono inoltre di fornire ulteriori informazioni riguardo alle fasi finali di riempimento della fossa bradanica. 2. inquadramento geologico i depositi quaternari rilevati nella parte orientale del foglio irsina ricadono nella fossa bradanica, che rappresenta l’avanfossa sudappenninica plio-pleistocenica, posta fra il fronte della catena appenninica a ovest, e l’avampaese apulo a est (migliorini, 1937; selli, 1962; ricchetti, 1980) (fig. 1, a, b). il riempimento di tale bacino ha inizio durante la parte alta del pliocene inferiore e il pliocene medio, su un’ampia area subsidente dell’avampaese apulo (ciaranfi et al., 1979), e i depositi risultanti si sedimentano su un substrato roccioso carbonatico in precedenza esposto (crescenti, 1975). lo spessore complessivo della successione bradanica supera i 2000 m; la parte sepolta della successione, infrapliocenico-infrapleistocenica, è principalmente caratterizzata da un complesso torbiditico (casnedi, 1988; 1991), mentre la parte affiorante, quaternaria, è costituita da argille siltose emipelagitiche (valduga, 1973; ciaranfi et al., 1979), al di sopra delle quali si rinvengono depositi grossolani di mare sottile, silicoclastici, meno diffusamente carbonatici, relativi sia alle ultime fasi di riempimento dell’avanfossa (ricchetti, 1967) sia al successivo sviluppo di depositi marini terrazzati (vezzani, 1967). la parte più interna dell’intera successione di riempimento è caratterizzata dalla presenza del cosiddetto “alloctono”, un complesso di terreni caotici di età pre-pliocenica che si interpone ai depositi di avanfossa sovrapponendosi a quelli torbiditici di età pliocenico-infrapleistocenica (casnedi et al., 1982). 393problemi di cartografia ... come accennato, la parte alta affiorante della successione plio-pleistocenica, spessa all’incirca 600 m, è rappresentata da depositi argillosi emipelagitici passanti in alto a una serie di depositi generalmente grossolani. la storia evolutiva del bacino, per quanto riguarda i depositi affioranti, è caratterizzata inizialmente da subsidenza parzialmente compensata da sedimentazione emipelagitica; dal pleistocene inferiore (emiliano), a partire dal settore centrale del bacino (area di banzi e genzano), si produce il colmamento a causa del sollevamento tettonico che interessa la regione (pieri et al. 1994; 1996). sulle emipelagiti, rappresentate dalle argille subappennine (azzaroli et al., 1968b; valduga, 1973; ciaranfi et al., 1979), si accumulano quindi depositi grossolani di mare sottile e/o continentali, corrispondenti allo stadio regressivo della storia evolutiva del bacino (pieri et al., 1996). secondo la carta geologica d’italia questi depositi, accumulatisi per meccanismi aggradazionali, costituiscono corpi tabulari attribuibili alle seguenti formazioni: sabbie di monte marano, calcareniti di monte castiglione, sabbie dello staturo, conglomerato di irsina (ricchetti, 1965; 1967; azzaroli et al., 1968a; 1968b; boenzi et al., 1971a; 1971b; valduga, 1973). studi più recenti, sia di carattere regionale (pieri et al., 1994; 1996; tropeano et al., 2002a; 2002b; sabato et al., 2004) che locale (sabato, 1996; lazzari, 1998; lazzari & pieri, 2002; cilumbriello, 2004; pieri et al., 2004), mostrano però un quadro geologico–stratigrafico molto differente. da questi lavori risulta che i depositi sabbioso-conglomeratici relativi alle fasi finali di riempimento della fossa bradanica si rinvengono in contatto sia transizionale che erosivo sulle argille subappennine e che alcuni corpi conglomeratici sono intercalati alle successioni sabbiose. inoltre tali depositi, denominati informalmente “depositi costieri regressivi” (fig. 1, c) da pieri et al. (1994) ed il cui spessore complessivo varia fino ad un massimo di 100 m, posseggono caratteri di facies variabili da marino-transizionali a continentali (massari & parea, 1988; 1990; pieri et al., 1994; 1996; 2004; sabato, 1996; lazzari, 1998; lazzari & pieri, 2002; tropeano et al., 2002a; 2002b; cilumbriello, 2004). 3. caratteri di facies e suddivisione formazionale dei depositi quaternari sabbioso-conglomeratici sommitali della fossa bradanica nel foglio irsina in questo capitolo saranno descritti i principali caratteri stratigrafici e di facies osservati per il complesso dei depositi sabbioso-conglomeratici poggianti sulle argille subappennine; lo studio di tali caratteri ha portato a proporre le suddivisioni formazionali introdotte nel foglio irsina della nuova carta geologica d’italia. nell’area del foglio irsina, il complesso dei depositi che poggia stratigraficamente sulle argille subappennine è rappresentato da una unità infrapleistocenica prevalentemente aggradazionale sabbiosa o sabbiosoconglomeratica (sabbie e conglomerati di monte s. marco) nell’ambito della quale si intercalano quattro membri conglomeratici prevalentemente progradazionali (conglomerato di giumentarizzo, conglomerato di madonna della pietà di irsina, conglomerato di monte s. angelo, conglomerato di s. antonio abate), (fig. 2). 394 fig. 2 carta geologica schematica del f° 471 “irsina”. schematic geological map of the f° 471 “irsina”. l. sabato, m. tropeano & p. pieri 395 al di sopra di tali depositi, in contatto erosivo e discordante si rinviene la formazione denominata sabbie e conglomerati di fosso macello. 3.1 sabbie e conglomerati di monte s. marco tale formazione, la cui istituzione è stata proposta precedentemente da sabato (1996), è costituita da depositi sabbiosi, o sabbioso-conglomeratici, affioranti a partire da quote variabili da circa 400 a circa 630 m s.l.m. tali depositi poggiano in continuità per alternanza sulle argille subappennine; hanno spessori variabili da 25÷30 m fino a circa 60 m, e i caratteri di facies sono in genere riferibili ad ambienti di transizione. di seguito vengono descritti i caratteri di facies di tale formazione nelle aree dove meglio affiora, e cioè nei dintorni dell’abitato di irsina (fig. 3). nell’area di irsina, nei pressi di località monte s. marco, tale unità è rappresentata da depositi principalmente sabbioso-arenacei e subordinatamente conglomeratici, aventi spessori di oltre 50 m. dal basso verso l’alto la formazione è costituita da alcuni metri di argille e argille siltose ben stratificate e intensamente bioturbate cui seguono silt con laminazione parallela e da ripple, ricchi di livelli sabbiosi, a volte con base erosiva, con lamine parallele e oblique a basso angolo e da ripples. in questi depositi sono presenti frequenti macrofossili e resti vegetali, oltre che abbondanti foraminiferi, sia bentonici che planctonici (sabato, 1996). tali depositi rappresentano i termini di passaggio alle argille subappennine e presentano caratteri di facies relativi ad ambienti di piattaforma-transizione a shoreface interessati da eventi di tempesta. al di sopra, per uno spessore di circa 25 m, si rinvengono sabbie e arenarie fini con laminazioni pianofig. 3 caratteri stratigrafici e di facies dei depositi sommitali della fossa bradanica affioranti nell’area di irsina (modificata da sabato, 1996). stratigraphic and facies characters of the upper deposits of the bradanic trough outcropping in the irsina area. (modified from sabato, 1996). problemi di cartografia ... 396 parallele, ondulate, da ripples o oblique a basso angolo (hummocky); spesso si osservano superfici erosive marcate da orizzonti di lamellibranchi, e frequente è la bioturbazione, prevalentemente da echinidi. tali caratteri di facies sono riferibili ad ambienti di shoreface inferiore (sabato, 1996). la parte alta della successione ha spessori variabili fino ad un massimo di circa 15 m. essa è rappresentata o da sabbie grossolane, bioturbate, ricche di lamellibranchi, passanti verso l'alto a conglomerati in strati a gradazione inversa, oppure da sabbie e conglomerati gradati inversamente, ricchi di ostree, e ben affioranti in località vallone delle noci e monte s. marco (figg. 3, 4). in genere i depositi sono clinostratificati, con angoli di circa 10° e direzione di progradazione da no a se. l'analisi di facies permette di riferire tali depositi ad ambienti di shoreface superiore, ghiaiosa o sabbiosa, passante a luoghi verso l'alto ad ambienti di foreshore (sabato, 1996), (fig. 4). a varie altezze stratigrafiche nelle sabbie e conglomerati di monte s. marco si rinvengono diversi corpi prevalentemente conglomeratici a geometria cuneiforme e con spessori variabili fino a un massimo di 60 m. tali corpi presentano caratteri di shallowing upward, e sono caratterizzati da facies di transizione, a luoghi passanti verso l’alto a facies continentali. in base ai caratteri di facies che verranno di seguito descritti, ognuno di tali corpi è riferibile a un apparato deltizio ghiaioso. il limite inferiore di questi corpi deltizi corrisponde ad una brusca variazione litologica rispetto alle sabbie; il contatto è generalmente di continuità stratigrafica, ma localmente è rappresentato da una superficie erosiva che in alcuni casi raggiunge le argille subappennine. questi corpi grossolani sono stati correlati per quota (considerando coevi, con questo criterio, differenti apparati deltizi non continui lateralmente) e sono stati riferiti, sotto il profilo stratigrafico, a quattro membri, che dal più antico sono: conglomerato di giumentarizzo, conglomerato di madonna della pietà di irsina, conglomerato di monte s. angelo, conglomerato di s. antonio abate (fig. 2). 3.2 conglomerato di giumentarizzo tale membro possiede uno spessore di almeno 8 m, ed è rappresentato da depositi prevalentemente conglomeratici, il cui contatto basale è brusco, ma di continuità, su facies sabbiose della formazione delle sabbie e conglomerati di monte s. marco, cui si intercala. alla base, per circa un metro, è caratterizzato da depositi conglomeratici con clasti arrotondati e subsferici del diametro di 10÷15 cm, cui segue un metro di alternanze decimetriche di arenarie e conglomerati. seguono 6 m di conglomerato a matrice sabbiosa (fig. 5), con rare lenti sabbiose, clinostratificato con foreset immergenti verso i quadranti sud-orientali; localmente si osservano livelli con clasti di dimensioni di circa 30÷40 cm, con fori di litodomi. in genere il conglomerato è disorganizzato, localmente matrice-sostenuto, con clasti solo raramente appiattiti, e a luoghi subangolari. i depositi sottostanti e sovrastanti il membro in oggetto sono rappresentati da sabbie e arenarie bioturbate e con strutture tipo hummocky. il conglomerato di giumentarizzo è riferibile ad un ambiente deltizio, le cui facies si intercalano bruscamente a facies sabbiose di ambienti di piattaformatransizione a shoreface, appartenenti alla formazione delle sabbie e conglomerati di monte s. marco (pieri et al., in prep.). 3.3 conglomerato di madonna della pietà di irsina a tale membro vengono attribuiti tre corpi cuneiformi prevalentemente conglomeratici, due ben affioranti, uno presso l’abitato di irsina e uno presso l’abitato di grassano, ed un terzo subaffiorante in località corona romana-mass.ia d’amati. nell’area di irsina tale membro presenta spessori variabili da pochi metri fino a circa 60 m, ed al suo interno si distinguono una unità bottomset, una foreset e una topset. l’unità foreset, a geometria cuneiforme, è formata da strati conglomeratici, e più raramente sabbiosi, clinostratificati, con spessori variabili da pochi metri nelle fig. 4 parte alta della formazione delle sabbie e conglomerati di monte s. marco dove si osservano livelli di conglomerati clinostratificati e ben selezionati, con ciottoli molto appiattiti e indicanti una prevalente immersione verso mare. caratteri di battigia. località monte s. marco. upper part of the sabbie e conglomerati di monte s. marco formation. clinostratified and well-sorted conglomeratic layers are evident; clasts are disc-shaped and show dipping seawards imbrications. gravelly beachface. san marco locality. l. sabato, m. tropeano & p. pieri aree prossimali, dove la sequenza è incompleta a causa della mancanza dell’unità bottomset, a circa 40 m nelle aree distali, dove aumenta la presenza di interstrati sabbiosi, e compaiono gradualmente gli strati appartenenti all’unità bottomset. i clinoformi mostrano una inclinazione variabile da circa 30° nelle aree prossimali (dove poggiano sulle argille subappennine lungo una superficie erosiva; figg. 6, 7), fino a raggiungere valori prossimi all'orizzontale nelle aree distali, poste verso se, dove le superfici dei clinoformi diventano tangenziali, e passano gradualmente all’unità bottomset. all’interno dell’unità foreset si individuano inoltre superfici erosive che separano gruppi di strati clinostratificati a diversa inclinazione. verso l’alto si osservano solchi erosivi prodotti da canali, profondi fino a 1 m e larghi alcuni metri, riempiti in basso da conglomerati e verso l’alto da depositi sab397 fig. 5 parte alta del conglomerato di giumentarizzo ; si osservi che le facies ghiaiose deltizie passano superiormente a facies sabbiose di ambienti di piattaforma-transizione a shoreface (formazione delle sabbie e conglomerati di monte s. marco). upper part of the deltaic conglomerato di giumentarizzo member. upwards it passes to sandy shoreface-transition to offshore environments (sabbie e conglomerati di monte s. marco fm.). fig. 6 il conglomerato di madonna della pietà di irsina in appoggio erosivo sulle argille subappennine nei dintorni dell’abitato di irsina. the conglomerato di madonna della pietà di irsina deltaic deposits erosively overlie the clay deposits of the argille subappennine fm. fig. 7 schema deposizionale dei depositi sommitali della fossa bradanica affioranti a irsina. (modificata da sabato, 1996). depositional scheme of the upper deposits of the bradanic trough outcropping in the irsina area. (modified from sabato, 1996). problemi di cartografia ... bioso-conglomeratici. i clinoformi hanno geometria sigmoidale, sono spessi alcuni decimetri, e mostrano gradazione inversa o inversa-normale. in genere hanno tessitura granulo-sostenuta, con matrice sabbiosa; localmente si osservano anche strati a tessitura matrice-sostenuta, con abbondante matrice siltoso-marnosa. gli strati sabbiosi e/o siltosi intercalati sono laminati e contengono livelli ghiaiosi o ciottoli sparsi. i clasti sono in genere ben arrotondati, e il grado di sfericità aumenta con la dimensione: fino a 10 cm hanno forma appiattita, mentre quelli con dimensioni maggiori, fino a 30 cm, hanno forma subsferica. le misure di paleocorrente, ricavate da assi di canale, embriciatura e direzione di progradazione dei clinoformi indicano provenienze da nno. come detto, distalmente i clinoformi diventano gradualmente suborizzontali (unità bottomset) e prevalentemente sabbiosi, e contengono una microfauna essenzialmente rappresentata da elphidium advenum, nonion depressulum. l'unità topset ha uno spessore massimo di circa 10 m ed è in contatto erosivo sull'unità foreset nelle aree prossimali (geometria obliqua), come si può osservare subito a ovest dell’abitato di irsina, mentre nelle aree distali passa gradualmente all’unità foreset (geometria sigmoidale). gli strati dell’unità topset sono suborizzontali, e sono rappresentati da conglomerati ricchi di intercalazioni sabbiose. i clasti hanno dimensioni inferiori rispetto a quelli dell’unità foreset, e mostrano una embriciatura verso mare ben sviluppata. l'analisi di facies permette di riferire l’intero corpo grossolano affiorante ad irsina ad un delta di tipo gilbert (sensu gilbert, 1885), dominato dall’azione delle onde (sabato, 1989; 1996), in parziale accordo con massari & parea (1990), che attribuiscono al corpo deltizio anche depositi non correlabili al corpo in oggetto, e qui riferiti a facies di avanspiaggia della locale porzione sommitale delle sabbie e conglomerati di monte s. marco (fig. 7). nell’area di grassano il corpo conglomeratico attribuito al membro del conglomerato di madonna della pietà di irsina poggia attraverso un brusco contatto prima transizionale e poi erosivo sulle sabbie e conglomerati di monte s. marco (fig. 8). si tratta di un corpo conglomeratico spesso circa 10 m, all’interno del quale si possono distinguere una unità foreset ed una topset (fig. 9). l’unità foreset è cuneiforme, il suo spessore decresce da 5 a 2,5 m spostandosi dalle aree prossimali a quelle distali, ed è formata da strati prevalentemente conglomeratici e subordinatamente arenacei, che progradano verso nord-est; la stessa unità verso l’alto mostra una complessa geometria obliquo-sigmoidale. i 398 fig. 9 contatto foreset/topset nel conglomerato di madonna della pietà di irsina affiorante in località cinti, a grassano. foreset/topset boundary in the conglomerato di madonna della pietà di irsina member. cinti locality, grassano village. fig. 8 schema deposizionale dei depositi sommitali della fossa bradanica affioranti a grassano. (modificata da tropeano et al., 2002a). depositional scheme of the upper deposits of the bradanic trough outcropping in the grassano area. (modified from tropeano et al., 2002a). l. sabato, m. tropeano & p. pieri clinoformi che compongono l’unità hanno spessori variabili da alcune decine di centimetri fino al metro, hanno una base angolare e/o tangenziale, una geometria cuneiforme e la loro inclinazione decresce verso bacino, variando da 17° a 5° circa. gli strati conglomeratici contengono clasti arenacei, granitici e carbonatici, ben arrotondati, e clasti silicei subangolari, con un diametro medio di 7÷8 cm. i clasti arenacei risultano ben appiattiti e mostrano embriciature dirette sia verso terra che verso mare; le evidenze di paleocorrente indicano direzioni prevalenti verso est. in genere i clinoformi conglomeratici sono clasto-sostenuti e gradati normalmente, con scarsa matrice sabbiosa grossolana; frequentemente si osserva un aumento della granulometria al piede, soprattutto dove l’altezza dei clinoformi è minore, con clasti di diametro da pochi centimetri fino a 60 cm; a luoghi si osserva la presenza di ostree incrostate su ciottoli, alla base dei clinoformi. i clinoformi arenacei mostrano una laminazione obliqua ad alto angolo immergente verso terra. il contatto fra l’unità foreset e quella topset è messo in evidenza da una netta diminuzione della dimensione dei clasti, con diametri in media di 3÷4 cm. l’unità topset (fig. 9) è formata per i primi 1,4 m da un conglomerato organizzato in strati orizzontali spessi circa 20 cm, che mostrano al loro interno una laminazione obliqua a basso angolo con immersioni verso mare; la matrice è rappresentata da sabbia grossolana e l’embriciatura dei clasti indica paleoflussi diretti verso ne. i successivi 2 m, che chiudono l’unità topset, sono composti da conglomerati molto ben selezionati, con ciottoli in media di 6÷7 cm, appiattiti e mostranti embriciature verso mare. al di sopra dell’unità topset si rinviene un conglomerato spesso circa 2 m, matrice-sostenuto e poco organizzato. l’analisi di facies relativa al membro del conglomerato di madonna della pietà di irsina affiorante nell’abitato di grassano porta ad interpretare questo corpo come un delta tipo gilbert (sensu gilbert, 1885) dominato dalle onde (pieri et al., in prep.) passante verso l’alto ad ambienti di shoreface e beachface ed infine ad ambienti alluvionali. distalmente, in località serra martello, i depositi deltizi passano e vengono coperti da arenarie di shoreface inferiore-transizione all’ offshore (fig. 8), appartenenti alle sabbie e conglomerati di monte s. marco. il terzo corpo attribuito al membro del conglomerato di madonna della pietà di irsina affiora a corona romana-mass.ia d’amati. in questo caso i depositi, ghiaioso-conglomeratici, sono spessi fino ad un massimo di circa 20 m, e sono in genere mal affioranti. il contatto basale è prima di continuità su facies sabbiosoconglomeratiche (nelle aree di affioramento più alte in quota) poi, distalmente (nelle aree di affioramento più basse in quota), di erosione su facies sabbiose e sabbioso-argillose appartenenti alle sabbie e conglomerati di monte s. marco. nei pressi di mass.ia d’amati, il conglomerato di madonna della pietà di irsina poggia in continuità su facies sabbiose con fitte laminazioni oblique (fig. 10) e strutture tipo gutter ghiaiose; qui il membro è ben affiorante solo per uno spessore di circa 8÷10 m, ed è caratterizzato per i primi 2 m da conglomerati in unità di 40÷50 cm con clasti arrotondati aventi dimensioni da pochi centimentri fino a 10 cm, a gradazione inversa, cui seguono livelli sabbiosi, a volte discontinui; raramente sono presenti clasti fuori misura, di 20÷30 cm di diametro. i successivi 2 m sono ricchi di intercalazioni sabbiose con lamine oblique a vario angolo, contenenti ciottoli con fori di litodomi. negli ultimi 4 m diminuiscono le intercalazioni sabbiose e i conglomerati diventano meno organizzati; la granulometria dei clasti aumenta, con medie di circa 6÷8 cm, e diventano più frequenti quelli di circa 20 cm. verso valle siggiano lo stesso corpo affiora in maniera molto discontinua; si riconoscono facies ghiaiose grossolane disorganizzate, con clasti di dimensioni superiori a quelle osservate nella sezione di mass.ia d’amati. queste facies poggiano in contatto erosivo su facies sabbiose e sabbioso-argillose appartenenti alle sabbie e conglomerati di monte s. marco. le facies caratteristiche del corpo conglomeratico descritto vengono riferite a sistemi deltizi ghiaiosi in regressione deposizionale su depositi di shoreface inferiore e progressivamente in regressione erosiva su depositi di piat399 fig. 10 contatto di transizione del membro del conglomerato di madonna della pietà di irsina sulle facies sabbiose della formazione delle sabbie e conglomerati di monte s. marco in località mass.ia d’amati. transitional contact of the conglomerato di madonna della pietà di irsina member on the sandy facies of the sabbie e conglomerati di monte s. marco fm. mass.ia d’amati locality. problemi di cartografia ... taforma-transizione a shoreface (pieri et al., in prep.). distalmente e frontalmente rispetto agli affioramenti conglomeratici, le successioni subaffioranti alla stessa quota sono rappresentate da facies sabbiose, appartenenti alle sabbie e conglomerati di monte s. marco. le successioni sabbiose raggiungono quindi quote superiori rispetto a quelle del locale appoggio basale del conglomerato di madonna della pietà di irsina; localmente ciò indica che nel tempo l’alimentazione ghiaiosa si è interrotta ed è ripresa la sedimentazione sabbiosa che aveva preceduto lo sviluppo del cuneo deltizio. 3.4 conglomerato di monte s. angelo a tale membro vengono attribuiti due corpi cuneiformi prevalentemente conglomeratici, affioranti uno in località monte s.angelo, l’altro nei pressi di mass.ia cecere. di seguito vengono descritti i caratteri di facies del primo, in quanto riferito al corpo meglio affiorante. in località monte s. angelo tale membro è rappresentato da un corpo conglomeratico spesso circa 30 m, con base erosiva. nella parte bassa si osservano livelli conglomeratici e livelli sabbiosi, entrambi di spessori decimetrici, che si alternano; le sabbie sono pulite e laminate, i conglomerati sono ben organizzati, con ciottoli appiattiti e di dimensioni in media di 7÷8 cm. nella parte alta aumentano i conglomerati, che diventano disorganizzati, con ciottoli prevalentemente subsferici, spesso di dimensioni di 20÷30 cm, raramente di 50 cm. le intercalazioni sabbiose, più rare rispetto alla parte inferiore, presentano strutture da trough. nella parte superiore i conglomerati si presentano clinostratificati, con inclinazioni di circa 10°. i caratteri di facies fanno riferire il corpo grossolano affiorante in località monte s. angelo ad un sistema deltizio (pieri et al., in prep.), in parziale accordo con massari & parea (1990), che attribuiscono questi depositi allo stesso apparato deltizio affiorante ad irsina. 3.5 conglomerato di sant’antonio abate tale membro affiora solo per una piccola parte nel f° 471 irsina; è rappresentato da un corpo conglomeratico cuneiforme, a base erosiva, con spessori variabili fino ad un massimo di 60 m. il corpo risulta clinostratificato con clinoformi inclinati fino a un massimo di circa 20°÷25°, aventi spessore massimo di 1 m, gradazione diretta, e più raramente inversa. i clasti, prevalentemente a composizione arenacea, hanno dimensioni medie di 5÷6 cm e massime di 20 cm, e si presentano generalmente ben arrotondati, e spesso appiattiti, dando indicazioni di paleocorrenti dirette verso i quadranti orientali. spesso sono presenti sabbie con ciottoli, in lenti o in livelli continui. la matrice è sabbioso-microconglomeratica, e solo raramente è molto abbondante. l’analisi di facies permette di riferire tali depositi ad un ambiente deltizio (pieri et al., in prep.). 3.6 sabbie e conglomerati di fosso macello al di sopra dei depositi sabbioso-conglomeratici (formazione delle sabbie e conglomerati di monte s. marco, e membri conglomeratici intercalati), poggia in netta discordanza tramite una superficie erosiva, un deposito sabbioso-conglomeratico (figg. 7, 8, 11), ricco di matrice terroso-argillosa rosso-bruna. lo spessore di tali depositi è variabile da luogo a luogo, da pochi decimetri fino a oltre 10 m. in generale si tratta di depositi matrice-sostenuti, con ghiaie e conglomerati disorganizzati, e con ciottoli aventi diametri variabili da 1 a 10 cm. a luoghi i depositi sono clinostratificati a basso angolo, o presentano canali di larghezza di poco superiore al metro. tali depositi inoltre sono ricchi di livelli carboniosi e croste manganesifere. in accordo con sabato (1996), i caratteri di facies fanno riferire le sabbie e conglomerati di fosso macello ad ambienti continentali di tipo alluvionale, successivi all’emersione dell’area e non correlabili con i depositi marino-transizionali e continentali delle formazioni sottostanti. 4. discussione 4.1 membri conglomeratici o sintemi? cartograficamente, ad eccezione del conglomerato di giumentarizzo, i corpi conglomeratici deltizi a 400 fig. 11 deposito sabbioso e/o ghiaioso-conglomeratico arrossato in facies alluvionale appartenente alle sabbie e conglomerati di fosso macello, in contatto discordante erosivo sui sottostanti depositi deltizi del conglomerato di madonna della pietà di irsina, in giacitura foreset, affiorante nei pressi dell'abitato di irsina. the alluvial deposits of the sabbie e conglomerati di fosso macello formation erosively overlie the gilbert-type delta sequence (conglomerato di madonna della pietà di irsina member) in irsina area. l. sabato, m. tropeano & p. pieri geometria cuneiforme riconosciuti nelle porzioni alte della successione regressiva bradanica sembrano poggiare sulla formazione delle sabbie e conglomerati di monte s. marco (fig. 2). questa apparente evidenza stratigrafica aveva portato inizialmente gli scriventi (anche in base a pressioni del servizio geologico) ad individuare come un supersintema l'insieme dei conglomerati deltizi e come sintema ogni singolo corpo deltizio. dopo una lunga fase di discussione ed ulteriori verifiche di campo si è optato per considerare i corpi conglomeratici come membri all'interno della formazione delle sabbie e conglomerati di monte s. marco, nonostante il loro frequente appoggio basale erosivo. questa scelta deriva in parte da evidenze di affioramento e in parte da considerazioni legate ai sistemi deposizionali di riferimento e ad una loro schematica interpretazione evolutiva in termini sequenziali. dal punto di vista geometrico, i corpi ghiaiosi deltizi occupano quasi sempre la porzione sommitale dei rilievi collinari bradanici. si è osservato però che la quota di appoggio dei corpi conglomeratici è sempre altimetricamente più bassa della quota raggiunta dall'unità sabbiosa affiorante frontalmente al corpo ghiaioso progradante (vedi p. es. lo schema di fig. 8). in pratica, durante la sedimentazione del corpo ghiaioso deltizio, distalmente si deponevano sabbie e argille; l'interruzione degli apporti ghiaiosi permetteva l'aggradazione di successioni esclusivamente sabbiose, che sigillavano distalmente il corpo ghiaioso deltizio o la sua porzione sabbiosa distale (praticamente indistinguibile utilizzando esclusivamente metodi di rilevamento di campo e considerando la scarsa continuità laterale degli affioramenti). questo giustificherebbe anche la presenza di facies ghiaiose non cartografabili all'interno della successione sabbiosa. l'interpretazione evolutiva in termini schematicamente sequenziali supporta la scelta formazionale operata. infatti regionalmente è stato suggerito che la successione regressiva bradanica rappresenti la testimonianza sedimentaria del colmamento del bacino durante le prime fasi del sollevamento regionale tuttora in atto (pieri et al., 1996; tropeano et al., 2002a, b). la registrazione del sollevamento tettonico è data dal fatto che la quota sommitale della chiusura delle successioni marine con facies di spiaggia o deltizie è progressivamente più bassa spostandosi dal fronte della catena verso sud-est. il sollevamento regionale, interferendo con le variazioni eustatiche del livello del mare, ha determinato la formazione di una successione regressiva che alternativamente è caratterizzata da facies prevalentemente sabbiose ed aggradazionali durante le fasi di relativa risalita e stazionamento alto del livello del mare (formazione delle sabbie e conglomerati di monte s. marco) e da facies prevalentemente ghiaiose e progradazionali (membri conglomeratici), poggianti e passanti distalmente a sabbie (formazione delle sabbie e conglomerati di monte s. marco), durante le fasi di relativa caduta e stazionamento basso del livello del mare (fig. 12), (tropeano et al., 2002a, b). inoltre, i depositi ghiaiosi deltizi che attualmente occupano quote simili si sono formati durante lo stesso intervallo di relativa caduta e stazionamento del livello del mare e, pur se originariamente non continui, occupano la stessa posizione stratigrafica e sono quindi stati raggruppati nello stesso membro (p. es. delta ghiaioso a irsina, delta ghiaioso a corona romana, e delta ghiaioso a grassano), (fig. 2). 4.2 il conglomerato di irsina: la fine di un mito la formazione del conglomerato di irsina, così come istituita durante i lavori per la realizzazione della carta geologica d’italia in scala 1:100.000 (azzaroli et al., 1968a, b; boenzi et al., 1971a, b), è stata considerata, e lo è tuttora da alcuni autori, il termine che regionalmente chiude la sequenza regressiva della fossa bradanica in appoggio sulla formazione delle sabbie di monte marano (fig. 12) e in eteropia con le formazioni delle argille calcigne e delle sabbie dello staturo. la maggior parte degli autori descrive la formazione del conglomerato di irsina come un deposito continentale in facies fluviale, con episodiche "sommersioni sotto le acque del mare"; tuttavia nell'area di spinazzola, banzi e genzano (compresa nei quadranti occidentali del foglio 188 “gravina di puglia”) l’unità viene descritta come di ambiente marino poco profondo. i nuovi rilevamenti, effettuati nell’area del foglio 471 “irsina” impongono una sostanziale revisione della suddivisione formazionale del complesso dei depositi sabbioso-conglomeratici posti al di sopra della formazione delle argille subappennine. prendendo come esempio emblematico quello dell’area dell’abitato di irsina (località-tipo per l’istituzione della formazione del conglomerato di irsina), e mettendo a confronto il rilevamento effettuato nell’ambito della carta geologica d’italia in scala 1:100.000 con quello effettuato nella stessa area per i rilevamenti del nuovo foglio in scala 1:50.000 risultano infatti notevoli differenze (fig. 13). in particolare, in base ai nuovi rilevamenti si evince come ad irsina siano presenti tre litosomi conglomeratici che non possono essere riuniti in una unica unità formale: un primo litosoma, di spessore ridotto, è rappresentato da conglomerati di avanspiaggia che localmente costituiscono le facies di chiusura di una successione regressiva prevalentemente sabbiosa; un secondo litosoma è rappresentato da un corpo conglomeratico clinostratificato di ambiente deltizio progradante ed in erosione sulla successione sabbioso-conglomeratica precedente e, distalmente, sulle argille; un terzo litosoma è rappresentato da una unità sabbioso-conglomeratica di origine continentale in erosione sulle unità precedenti. nel vecchio rilevamento i tre litosomi discordanti fra loro erano identificati come la formazione del conglomerato di irsina e venivano rappresentati come un unico corpo tabulare, aggradante e in parziale eteropia con la sottostante formazione delle sabbie di monte marano; è evidente da quanto descritto in precedenza che nella formazione venivano erroneamente inclusi depositi che nel nuovo rilevamento vengono riferiti alla locale parte alta della formazione delle sabbie e conglomerati di monte s. marco, al membro del conglomerato di madonna della pietà di irsina e alla formazione delle sabbie e conglomerati di fosso macello, che oltre a possedere caratteri di facies nettamente differenti, si trovano in posizioni stratigrafiche ben distinte. anche nelle altre località rilevate si è riscontrata la presenza di più litosomi conglomeratici, non distinti nella vecchia cartografia. si evince che, regionalmente, nella formazione del conglomerato di irsina erano stati 401problemi di cartografia ... praticamente inclusi tutti i litosomi conglomeratici affioranti (ed anche le successioni sabbiose ad essi intercalate). dall’interpretazione ambientale dei conglomerati si ricava inoltre che la gran parte degli affioramenti osservati non appartiene a corpi che originariamente possedevano eccessiva continuità laterale. quindi la soluzione stratigrafica ricavata localmente e la sua trasposizione cartografica non può essere adottata in maniera semplicistica per tutto il bacino. la tabularità dei depositi riconosciuta a livello regionale riguarda quindi l’assetto tettonico (indeformato) dei depositi regressivi della fossa bradanica, ma non, nel dettaglio, la loro distribuzione stratigrafica areale. in definitiva, non esiste un unico corpo prevalentemente conglomeratico e coevo che chiude la serie bradanica e che possa assumere un rango formazionale e pertanto la formazione del conglomerato di irsina deve essere emendata. conclusioni dal rilevamento geologico e dall’analisi di facies compiuta sui depositi regressivi dell’area del foglio irsina si ricava un modello deposizionale rappresentato da sistemi costieri s.l. (formazione delle sabbie e conglomerati di monte s. marco e membri conglomeratici intercalati) che progradavano nel bacino bradanico poggiando e passando distalmente a depositi emipelagitici (argille subappennine). su questo complesso di depositi marini, una volta esposti, si sviluppavano in erosione sistemi alluvionali (formazione delle sabbie e 402 fig. 12 in alto, schema stratigrafico derivante dalla carta geologica d’italia f° 188 “gravina di puglia” (scala 1: 100.000); in basso, schema stratigrafico derivante dai rilevamenti del f° 471 “irsina” (scala 1: 50.000). stratigraphic schemes of the bradanic trough according to the geological map f° 188 “gravina di puglia” (on scale 1: 100.000) above, and according to the geological map f° 471 “irsina” (on scale 1: 50.000), below. l. sabato, m. tropeano & p. pieri conglomerati di fosso macello). le formazioni così definite sono diacrone in tutto il bacino, ringiovanendosi a sud verso il mare ionio. la formazione del conglomerato di irsina, così come istituita negli anni '60 e nota in letteratura, va emendata, in quanto è un insieme di più litosomi di età e significato ambientale e stratigrafico differente. i dati esposti dimostrano inoltre che i depositi e la superficie sommitale dei rilievi bradanici, a differenza di quanto sostenuto anche recentemente, non rappresentano un episodio unico di regressione, ma una serie di episodi regressivi registrati durante il sollevamento tettonico del bacino. l’organizzazione stratigrafica dei depositi mostra infatti un trend progradazionale piuttosto che aggradazionale. a tale proposito, le quote massime a cui si rinvengono i depositi regressivi della fossa bradanica (da circa 630 m s.l.m., fino a circa 400 m s.l.m. nell'area rilevata spostandosi dalla catena verso e) non va intesa come il risultato di un sollevamento differenziale del bacino successivo alla sedimentazione della successione marina costiera, ma in larga parte come la registrazione del sollevamento regionale in atto durante la sedimentazione. ringraziamenti si ringraziano il prof. n. ciaranfi e il dott. s. longhitano per la lettura critica del manoscritto. il lavoro è stato eseguito nell’ambito del progetto carg, anche con fondi m.i.u.r. anni 2001, 2002 (responsabile prof.ssa sabato). 403 fig. 13 in alto, confronto fra la carta geologica dell’area di irsina nel f° 188 gravina di puglia (a sinistra), e nel f° 471 irsina (a destra). in basso, confronto fra il vecchio e il nuovo schema stratigrafico dei depositi sommitali della fossa bradanica affioranti nella stessa area. above, comparison between the geological map of the irsina area in the f° 188 gravina di puglia (on the left) and in the f° 471 irsina (on the right). below, comparison between the old and the new stratigraphic scheme of the upper deposits of the bradanic trough in the irsina area. problemi di cartografia ... lavori citati azzaroli a., perno u. & radina b. (1968a) note illustrative della carta geologica d'italia alla scala 1:100.000 del foglio 188 "gravina di puglia". serv. geol. d'it., 57 pp. azzaroli a., radina b., ricchetti g. & valduga a. (1968b) note illustrative della carta geologica d’italia alla scala 1:100.000 del foglio 189 "altamura". serv. geol. d'it., 22 pp. boenzi f., palmentola g. & valduga a. (1971a) note illustrative della carta geologica d'italia alla scala 1:100.000 del foglio 200 "tricarico". serv. geol. d'it., 46 pp. boenzi f., radina b., ricchetti g. & valduga a. (1971b) note illustrative della carta geologica d'italia alla scala 1:100.000 del foglio 201 "matera". serv. geol. d'it., 48 pp. casnedi r. (1988) la fossa bradanica: origine, sedimentazione e migrazione. mem. soc. geol. it., 41, 439-448. casnedi r. (1991) hydrocarbon accumulation in turbidites in migrating basins of the southern adriatic foredeep (italy). in: bouma & carter (eds.) “facies models”, 219-233. casnedi r., crescenti u. & tonna m. (1982) evoluzione della avanfossa adriatica meridionale nel plio-pleistocene, sulla base di dati di sottosuolo. mem. soc. geol. it., 24, 243-260. ciaranfi n., maggiore m., pieri p., rapisardi l., ricchetti g. & walsh n. (1979) considerazioni sulla neotettonica della fossa bradanica. prog. fin. geod. del cnr, 251, 73-95. cilumbriello a. (2004) caratteri stratigrafici dei depositi regressivi pleistocenici della fossa bradanica nell’area di banzi e genzano di lucania (basilicata). università della basilicata. tesi di laurea, università della basilicata, 90 pp. crescenti u. (1975) sul substrato pre-pliocenico dell'avanfossa appenninica dalle marche allo jonio. boll. soc. geol. it., 94, 583-634. gilbert g.k. (1885) the topographic features of lake shores. u.s. geol. surv., 5th annual rep., 69-123. lazzari m. (1998) evoluzione stratigrafica e paleoambientale della parte sommitale della successione della fossa bradanica fra l'appennino meridionale e le murge settentrionali. considerazioni sull'evoluzione tettonico-sedimentaria del bacino bradanico nel pleistocene inferiore. tesi di dottorato, università di bari, 144 pp. lazzari m. & pieri p. (2002) modello stratigraficodeposizionale della successione regressiva infrapleistocenica della fossa bradanica nell’area compresa fra lavello, genzano e spinazzola. mem. soc. geol. it., 57, 231-237. massari f. & parea g.c. (1988) progradational gravel beach sequences in a moderateto high-energy, microtidal marine environment. sedimentology, 35, 881-913. massari f. & parea g.c. (1990) wave dominated gilbert-type gravel deltas in the interland of the gulf of taranto (pleistocene, southern italy). in: colella & prior (eds.) “coarse-grained deltas” , spec. publs int. ass. sediment., 10, 113-127. migliorini c. (1937) cenno sullo studio e sulla prospezione petrolifera di una zona dell'itala meridionale. ii congr. mondiale del petrolio, parigi, 1-11. pieri p., boenzi f., gallicchio s., sabato l., tropeano m. & vitale g. note illustrative della carta geologica d’italia alla scala 1:50.000 del foglio 471 “irsina”. sottoposto per la stampa su: serv. geol. d'it. pieri p., sabato l. & tropeano m. (1994) evoluzione tettonico-sedimentaria della fossa bradanica a sud dell’ofanto nel pleistocene. in: osanna (ed.) "guida alle escursioni". 77° cong. naz. soc. geol. it., bari. quad. bibl. prov. matera, 15, 35-54. pieri p., sabato l. & tropeano m. (1996) significato geodinamico dei caratteri deposizionali e strutturali della fossa bradanica nel pleistocene. mem. soc. geol. it., 51, 501-515. pieri p., sabato l. & tropeano m. (2004) pliopleistocene stratigraphic and tectonic evolution of the foreland-foredeep-chain system in southern italy . in: memorie descrittive della carta geologica d’italia, vol. lxiii, field trip guide book, 32nd int. geol. congress, august 20-28 2004, florence (italy), vol. n° 1, p35, 44 pp. ricchetti g. (1965) alcune osservazioni sulla serie della fossa bradanica. le "calcareniti di m. castiglione”. boll. soc. nat. in napoli, 74, 3-11. ricchetti g. (1967) lineamenti geologici e morfologici della media valle del fiume bradano. boll. soc. geol. it., 86, 607-622. ricchetti g. (1980) contributo alla conoscenza strutturale della fossa bradanica e delle murge. boll. soc. geol. it., 49, 421-430. sabato l. (1989) caratteri stratigrafici e sedimentologici dei depositi affioranti nella zona di irsina (fossa bradanica). rapporto interno cnr, ist. ric. argille, 20 pp. sabato l. (1996) quadro stratigrafico-deposizionale dei depositi regressivi nell'area di irsina (fossa bradanica). geologica romana, 32, 219-230. sabato l., tropeano m., cilumbriello a., palladino g. & pieri p. (2004) latest stages of filling of a confined and uplifting foreland basin (bradanic trough, southern italy). in: abstracts 32nd int. geol. cong., florence (italy), august 20-28, part 1, 697. selli r. (1962) il paleogene nel quadro della geologia dell’italia meridionale. mem. soc. geol. it., 3, 737789. tropeano m., sabato l., pieri p. (2002a) filling and cannibalization of a foredeep: the bradanic trough, southern italy. in: jones & frostick (eds.) “sediment flux to basins: causes, controls and consequences” , geological society, london, spec. publ., 191, 55-79. tropeano m., sabato l., pieri p. (2002b) the quaternary “post-turbidite” sedimentation in the south apennines foredeep (bradanic trough southern italy). boll. soc. geol. it., vol. sp. n° 1, parte i, 449-454. valduga a. (1973) fossa bradanica. in: utet (ed.) “geologia dell'italia”. a cura di a. desio, 692-695. vezzani l. (1967) i depositi plio-pleistocenici del litorale ionico della lucania. atti acc. gioenia sc. nat. in catania, s. vi, 18, 159-180. 404 ms. ricevuto il 21 maggio 2004 testo definitivo ricevuto l’8 ottobre 2004 ms. received: may 21, 2004 final text received: october 8, 2004 l. sabato, m. tropeano & p. pieri imp.bruschi&cendrero geosite evaluation; can we measure intangible values? viola maria bruschi & antonio cendrero departamento de ciencias de la tierra y física de la materia condensada (citimac), facultad de ciencias, universidad de cantabria. avda de los castros s/n 39005, santander, cantabria (spain). e-mail: bruschiv@unican.es abstract: v.m. bruschi & a. cendrero, geosite evaluation; can we measure intangible values? (it issn 0394-3356, 2005). a discussion on issues to be addressed in the process of cataloguing and assessing geosites is presented. different stages of the process are considered: identification, classification, inventory, evaluation, protection and use. inventories to be elaborated should be satisfactory from different points of view: scientific quality of sites, definition of protection levels, possibility of educational or recreational use, or potential for generating economic activities. a problem that permeates all stages of the process is subjectivity. establishment of ranks of scientific interest for sites in a region, proposals for protection measures or drafting plans for the use of geosites cannot be based exclusively on scientific, objective criteria. subjectivity is an unavoidable (perhaps even desirable) part of all of them. this represents an important difficulty because if protection and use plans for geosites are to be successful, they should be based on transparent criteria that can be subject to external, independent scrutiny and evaluation. this should include some sort of validation to determine to what extent classifications and proposals presented reflect social values, be they expressed by specific stakeholder groups (earth scientists, decision makers, elected officials, conservationists) or general public. if those values are well reflected plans will be socially acceptable and more likely to be useful. an approach is presented based on the definition of three groups of criteria, related to: a) intrinsic quality of sites; b) potential threats and protection needs; c) potential for use. indicators are presented for each criterion. particular efforts have been made to propose indicators that can be expressed by means of continuous variables. when this has not been possible categorical, “objective” variables are used. combination of those indicators into different types of indices can be used as a means to “measure” the type of intangible qualities mentioned above. the advantage of the approach proposed is that numerical classifications of sites obtained using that kind of “quality models”, can be validated through comparison with independent external opinions or evidences. two applications to case studies for cataloguing and assessing are presented. the first one concerns the assessment of geosites using clearly-stated criteria based on observable characteristics. the methodology is applied to an existing geosites inventory; validation is carried out by comparison with a very much appreciated geomorphic landmark in the same region as well as with expenditure on two sites subject to restoration. the second case study refers to the identification and ranking of geosites for a new inventory. ranks obtained directly from surveys among geomorphologists are compared with those derived from the application of the method. the analyses presented indicate that the “quality models” used yield results that coincide quite well with independent assessments or evidences for “clearly good quality sites”. agreement is less satisfactory for sites lower down in the ranks. some inconsistencies between direct subjective assessment by individual experts and systematic assessment based on quality criteria proposed by the same expert have also been found. it is concluded that the method in its present form provides a satisfactory “coarse grain” image of sites’ quality but improvements are needed. riassunto: v.m. bruschi & a. cendrero, la valutazione dei geositi: possiamo misurare valori intangibili? (it issn 0394-3356, 2005). nel presente lavoro si tratteranno i principali aspetti relativi al procedimento della catalogazione e della valutazione dei “geositi” e, più in concreto, si tratteranno i diversi stadi del procedimento generale quali, la identificazione, la classificazione, l’inventario, la valutazione, la protezione e l’uso. gli inventari dei geositi devono esssere elaborati in modo soddisfacente dal punto di vista della qualità scientifica dei beni geologici, della definizione dei diversi livelli di protezione, dei possibili usi educativi e ricreativi e dal punto di vista del potenziale per lo sviluppo di attività economiche. uno dei principali problemi che interessano il trattamento dei “geositi” e i differenti stadi dell’analisi è la soggettività. la determinazione del grado d’interesse scientifico proprio dei beni geologici di una regione, le proposte relative alle misure di protezione o all’uso potenziale dei sopracitati beni non possono essere elaborate unicamente con criteri scientifici o obbiettivi; la soggettività deve essere considerata parte inevitabile del procedimento generale. ciò rappresenta una difficoltà importante dato che, per ottenere una protezione ed un uso soddisfacenti dei geositi, è necessario basare gli studi su criteri trasparenti e che possano essere soggetti a valutazioni e giudizi esterni ed indipendenti. ciò implica la necessità di una valutazione che permetta definire fino a che punto le classificazioni e proposte elaborate riflettono l’opinione pubblica, sia per quanto riguarda gruppi d’esperti che per quanto riguarda un pubblico più ampio. l’unica forma per rendere efficaci ed utili le proposte eleborate per il trattamento dei geositi, è che queste ultime riflettano in modo adeguato l’opinione pubblica. la metodologia che si presenta a continuazione si basa sui tre seguenti pricipali gruppi di criteri quali, la qualità intrinseca dei geositi, le potenziali minacce e necessità di protezione ed il potenziale d’uso, per ognuno dei quali si propongono degli indicatori di misura. é stato prestato un particolare sforzo nel proporre indicatori che possano essere rappresentati con variabili continue, quando non è stato possibile, si è passati a variabili categoriche cercando sempre di mantere l’oggettività dell’analisi. per misurare le qualità descritte anteriormente applicando i relativi modelli di qualità e valutazione, sono state utilizzate varie combinazioni degli indicatori attraverso l’applicazione di indici numerici. il principale vantaggio di questa metodologia risiede nella possibilità di comprovare i risultati e, di conseguenza, il metodo stesso, attraverso opinioni esterne ed indipendenti. il modello iniziale può esssere perfezionato fino ad ottenere una buona corrispondenza con le valutazioni effettuate da chi è preposto a decidere. si presentano due applicazioni relative al processo di catalogazione e di valutazione dei geositi. la prima si riferesce alla valutazione dei geositi attraverso l’uso di criteri definiti basandosi su caratteristiche oggettive e osservabili. la metodologia viene applicata a un inventario di geositi esistente, la validazione del metodo è stata ottenuta attraverso la comparazione con i risultati derivanti dalla valutazione di un geosito, il cui interesse è ampiamente riconosciuto ed accettato nella regione, e di altri due beni soggetti a ripristino e situati in due regioni limitrofe alla zona oggetto dello studio. la seconda applicazione si riferisce alla identificazione e categorizzazione dei geositi per la elaborazione di un nuovo catalogo. la categorizzazione, ottenuta attraverso un sondaggio sottoposto a geomorfologi, è stata confrontata con il “medello di qualità” constatando che i risultati ottenuti dai due metodi (modello di qualità e valutazione indipendente) coincidono abbastanza, soprattutto per quanto riguarda i beni di qualità elevata. per i geositi ritenuti di qualità inferiore, la coincidenza fra i due metodi è decisamente inferiore. inoltre è stato evidenziato un certo disaccordo fra la valutazione dei geositi soggettiva realizzata dagli esperti e la valutazione sistematica elaborata sulla base di criteri di qualità proposti dagli esperti stessi. per concludere, nonstante sia necessario apportare miglioramenti, il metodo presentato rispecchia in modo soddisfacente la valutazione dei geositi di buona qualità. keywords: geosites, cataloguing, evaluation, intangible values, quality indicators, validation, spain. parole chiave: geositi, catalogazione, valutazione, valori intangibili, indicatori di qualità, validazione, spagna. il quaternario italian journal of quaternary sciences 18(1), 2005 volume speciale, 293-306 294 v.m. bruschi & a. cendrero 1. introduction identification, cataloguing and evaluation of geosites is a complex task that stands somewhere between scientific analysis and evaluation of historical, artistic or cultural heritage. this implies the need to combine very different criteria, approaches and, in particular, disciplinary cultural backgrounds. in the process of inventorying and assessing geosites it is necessary to combine scientific criteria with other criteria related to intangible values (panizza & piacente, 1999; poli, 1999) more commonly associated with artistic or historical objects. such values include, for instance, “quality of the natural heritage”, “cultural or educational interest” (reynard et al., 2002), “tourism and recreation potential” or “protection need” (cendrero, 2000). the different tasks to be performed require, on the one hand, data collection and scientific interpretation; that is, activities normally associated with the “objective” natural or experimental sciences. on the other hand, it is necessary to make value judgements, much more common in the subjective realm of artistic object’s assessment. in a scientific environment as the earth sciences it is normally expected that opinions (scientific interpretations) are based on transparent criteria that can be subject to external, independent scrutiny and evaluation. this should include the possibility to replicate, by any operator, results obtained by another one. it is therefore convenient to design and test procedures for cataloguing and evaluation that are based on clearlystated criteria and, as far as possible, quantitative parameters. such criteria and parameters could be used to derive numerical indices obtained through well defined steps and methods (mohr, 1988). the use of that type of approach can help to “validate” the method; that is to determine to what extent assessments by a group of experts are coincident with those by other experts in the discipline. it is also desirable to “validate” what we could name “scientific consensus” against the perception by other stakeholder groups such as experts from other disciplines, decision makers, elected officials, conservationists or general public. if the method, criteria and procedure used yield results that reflect reasonably well social values and interests, the final aim of promoting careful use and conservation of geosites is more likely to be achieved. a series of stages can be identified in the general process that starts with the identification of valuable geosites and leads to their protection and use. those stages are: a) site identification; b) inventory and classification; c) evaluation; d) protection; e) use. it is important to bear in mind that the first three stages should not be the aim of this type of undertaking; they are simply means to achieve the final goal indicated above: conservation and use. it follows that inventories of geosites in general and geomorphosites in particular should be satisfactory from a variety of viewpoints. those include, obviously, quality of sites, but also usefulness for defining protection levels, carrying out educational or recreational activities, or potential to generate economic activities (martini, 2000). that is, establishment of value ranks for geosites within a region, proposals for protection measures or plans for their use should not be based exclusively on scientific criteria. if those proposal and plans are to be successful they should be accepted by local society. comparison with what has happened in many countries with respect to conservation or rehabilitation of historical and artistic heritage provides some interesting lessons. there are many examples of badly deteriorated historical buildings whose restoration and protection was achieved only when they were dedicated to purposes perceived as “useful” by society as a whole (administration or education buildings, hotels and restaurants, museums, etc). this is more difficult in the case of geosites, but it is probably worth making efforts to promote their “social usefulness”, other than the obvious preservation of a part of natural heritage. in what follows below some proposals are presented towards the establishment of systematic procedures for geosite identification, cataloguing and assessment, that try to minimise the problem of subjectivity and, at the same time, help to define protection and development actions. 2. proposed procedure accepting that subjectivity (based on expert’s opinion) is an unavoidable part of the overall inventory and assessment process, the procedure presented is based on the definition of a series of successive steps that facilitate the establishment of clearly-stated criteria. those steps are: • identification of significant criteria (“qualities” of geosites) • definition of indicators to “measure” each criterion • establishment of value ranks for individual indicators • establishment of procedure for the integration of individual qualities (formulation of a “value model”) • validation probably the most important step in the process is the identification of suitable indicators for ranking sites according to the different qualities considered. ideally all such indicators should be based on the use of continuous variables, but this will not always be possible. another important, but difficult, step is validation. contrary to models normally used in geomorphology, that try to represent physical processes, “value models” used in geosite’s assessment try to reflect opinions, be they from experts, other stakeholders groups or general public. in the case of physical models validation can easily be performed by comparing model-predicted and actual process behaviour. validation of “quality or value models” rests on a somewhat more shaky ground; probably the simplest form of validation is comparison between assessment by a study team and those of external expert teams or different social groups. the procedure proposed starts with the identification of a series of criteria that can be grouped into three main categories (cendrero, 2000): a) intrinsic quality of sites (scientific merit) • abundance/rarity • degree of scientific knowledge • usefulness as process model/example • diversity of elements of interest • age • type locality • association with historical, archaeological, artistic heritage • association with other natural heritage • state of conservation b) potential for use (social usefulness) • activities that can be carried out • observation conditions • accessibility • extent 295geosite evaluation ... • proximity to service centres • socio-economic condition of the area c) potential threats and protection needs (urgency to act) • inhabitants in the surroundings • present or potential threats • possibility to collect objects • relationship to existing planning • interest for mineral exploitation • land ownership indicators that can be used to “measure” those criteria are shown in tables 1, 2 and 3. for each indicatab. 1 indicators and ranks for criteria related to intrinsic quality. capital symbols in brackets correspond to the ones used for qi calculation in expression [1]. indicators for which only three levels could be defined are marked with an asterisk (*). indicatori e ranghi definiti per il criterio relativo alla qualità intrinseca. in maiuscolo e fra parentesi i simboli corrispondenti agli indicatori usati per il calcolodella qi secondo l’espressione matematica corrispondente [1]. gli indicatori per i quali è stato possibile definire solo tre ranghi vengono segnalati con un asterisco (*). intrinsic quality indicators ranks abundance/rarity (a) 4 only one example in the region 3 2-4 examples 2 5-10 examples 1 11-20 examples 0 >20 examples degree of scientific knowledge (k) 4 more than 1 ph.d. thesis; several papers in international/national journals 3 1 ph.d.thesis; at least 1 international or several national papers 2 1 national paper 1 some notes in national journals or articles in regional/local journals 0 no publications (*) usefulness as process 4 present, active process clearly visible/interpretable model/example (ex) 2 erosion/deposition features of present processes not clearly defined 0 fossil forms and/or deposits whose use for interpretation of past processes is difficult diversity of elements (geomorphic, 4 5 or more elements stratigraphic, paleontologic, etc) 3 4 elements(d) 2 3 elements 1 2 elements 0 only 1 element age (difficult, disputable criterion; 4 mesozoic or older it can be accepted that “other 3 cenozoicfactors being equal”, the older the 2 lower pleistocenebetter) (ag) 1 upper pleistocene 0 holocene (*) type locality? (t) 4 formally recognised type locality 2 secondary or reference type locality 0 not proposed as type locality association with historical, 4 presence of archaeological and several types of other elements archaeological, artistic heritage 3 archaeological and one additional type of element(ch) 2 archaeological remains 1 other, non-archaeological elements 0 no additional elements (*) association with other natural 4 outstanding landscape and valuable flora and fauna heritage (n) 2 outstanding landscape or valuable flora/fauna 0 valuable landscape state of conservation (c) 4 well preserved; no degradation 3 damage to minor characteristics 2 partially affected by human activities, but character of site remains 1 very affected by human activities; many characteristics degraded 0 intense degradation; loss of the site’s character 296 v.m. bruschi & a. cendrero tab. 2 indicators and ranks for criteria related to potential for use. capital symbols in brackets correspond to ones used for ui calculation in expression [1]. indicators for which only three levels could be defined are marked with an asterisk (*). indicatori e ranghi definiti per il criterio relativo al potenziale d’uso. in maiuscolo e fra parentesi i simboli corrispondenti agli indicatori usati per il calcolo della ui secondo l’espressione matematica corrispondente [1]. gli indicatori per i quali è stato possibile definire solo tre ranghi vengono segnalati con un asterisco (*). potential for use indicators ranks activities that can be carried out 4 5 or more activities (scientific, educational, tourism, 3 4 activitiesrecreation, object collecting, etc.) 2 3 activities(act) 1 2 activities 0 1 activity (*) observation conditions (o) 4 no limitations for entry; no visual obstructions 2 some physical limitations for access and/or viewing 0 physical difficulties for access and views obstructed by constructions vegetation, etc. accessibility (acc) 4 direct access through main road 3 access through local roads 2 access through unpaved roads or tracks 1 no road access but < 1 km from the nearest one 0 > 1 km from the nearest raod access extent (m2) (e) 4 > 106 3 105 106 2 104 105 1 103 104 0 < 103 proximity to service centres (s) 4 centre > 10,000 inhabitants and diversity of lodging and catering facilities within 5 km 3 locality > 10,000 inhabitants and some facilities within 5 km 2 5 – 20 km to lodging/catering facilities 1 20 – 40 km 0 > 40 km (*) socio-economic condition 4 per capita income and education > 15% above national average of the area (se) 2 national average 0 > 15% below national average tor a five-term (0 – 4) rank has been established. thus, indicators initially expressed by means of different, heterogeneous units are transformed into homogeneous categorical units. the following expression provides a “quality model” that can be applied to geosites using indicators presented above. vsgi = (qi+ui+pi)/3 [1] where: vsgi = value or merit of geosite (0-1); qi = intrinsic quality (0-1); ui = potential for use (0-1); pi = protection need (0-1). qi = (a×wa + k×wk + ex×wex + d×wd + ag×wag + t×wt + ch×wch + n×_wn + c×wc) / 4 ui = (act×wact + o×wo + acc×wacc + e×we + s×ws + se×wse) / 4 pi = (i×wi + t×wt + co×wco + p×wp + m×wm + l×wl) / 4 wi = weight of each indicator (σwi=1). the meaning of variables in the expression above is shown in tables 1, 2 and 3. of course, other “quality models” can be considered, such as: vsgi = ci (2qi+pi)/12 [2] where: ci = degree of conservation of geosites (0-4); qi = intrinsic quality of geosites (0-1); pi = potential for use of geosites (0-1). models assume that if a site ranks high with respect to the three qualities considered (scientific merit, social usefulness, urgency to act) can be considered as very valuable and should be included in inventories and protection plans. indicators and models proposed provide a means to express those intangible qualities by means of numerical indices, using transparent models that yield replicable results. the use of such indices should facilitate the incorporation of geosites into a variety of assessments for environmental decision making. 3. application to case studies the concepts and general procedure described above have been applied to two case studies, in order to test the validity of the method proposed. 297 3.1 geosites evaluation within the eia process. one case study deals with the evaluation of an existing inventory of geosites in an area of northern spain (fig. 1), as part of the eia process for a new motorway (bonachea et al., 2003). the procedure described here is an improvement of a former proposal; a more detailed description can be found in rivas et al. (1997). the inventory used is shown in figure 2. the value of each geosite was defined using a “quality model” slightly different to the ones presented above [1, 2]. vsgi = ci (2qi+ pi) / 48 [3] where: ci = degree of preservation (0 – 4); qi = intrinsic quality (0 – 4); pi= potential for use (0 – 4); vsgi = value of site (0-1) quality (q) was defined as: qi = wa × a + we × e + wk× k + wex × ex + wd × d where: a: relative abundance of the site’s type; d: diversity of geological/geomorphological elements; e: extent of the site; ex: value of site as example of geomorphological processes; k: degree of knowledge about site. w: weights of the factors considered; σ w = 1 potential for use (p) was obtained using a similar expression: pi = wac × ac + wo × o + ws × s + wh × h + wacc × acc where: geosite evaluation ... tab. 3 indicators and ranks for criteria related to potential threats and protection needs. capital symbols in brackets correspond to ones used for pi calculation in expression [1]. indicators for which only three levels could be defined are marked with an asterisk (*). indicatori e ranghi definiti per i criteri relativi alle potenziali minacce e alle necessità di protezione. in maiuscolo e fra parentesi i simboli corrispondenti agli indicatori usati per il calcolo della pi secondo l’espressione matematica corrispondente [1]. gli indicatori per i quali è stato possibile definire solo tre ranghi vengono segnalati con un asterisco (*). potential threats and protection needs indicators ranks inhabitants in the surrounding 4 > 100,000 (within a 25 km radius) (i) 3 50,000 – 100,000 2 25,000 – 50,000 1 10,000 – 25,000 0 < 10,000 (*) present or potential threats (t) 4 area with clear urban-industrial development or projects for new infrastructures 2 intermediate area; no immediate development projects but clear expectations for the near future 0 rural area; no expectations of urban-industrial-infrastructure development in the foreseeable future (*) possibility to collect objects 4 fossil, mineral or rock samples can be collected and site damaged (co) 2 objects can be collected without major damage to the site 0 no possibility to collect objects relationship to existing planning 4 area classified for urban, industrial or service uses (p) 3 no existing plans 2 site not protected but in area classified as rural in existing plans 1 site in area with some protection status in local/provincial plans 0 included within national park or other nationally protected space interest for mineral exploitation (m) 4 high mineral interest and current mining permits in the area 3 area with reserves of low-unitary value resources and where quarrying is currently allowed 2 area with reserves of low-unitary value resources but where quarrying is not currently allowed 1 some indications of mineral resources 0 no mining interest (*) land ownership (l) 4 site located in private land 2 both public and private property 0 public property fig. 1 location map. inquadramento geografico dell’area. 298 ac: types of activities that can be carried out on site; o: observation conditions; s: availability of services; h: number of inhabitants in surrounding area acc: accessibility; w: weights of factors considered; σ w = 1. table 4 shows the indicators and ranks (0 – 4 scale) established for the different parameters used to calculate the value of geosites (bonachea et al., 2003). table 5 presents, for all geosites analysed, values of the different factors considered as well as those for c, q, p and vsgi. to validate those results comparison with wellknown and socially appreciated geomorphologic landmarks in the region was made. geosites chosen as standards for comparison are the “ratón de guetaria” (guetaria mouse; fig. 3), probably the best known and most appreciated geomorphic landmark in the province of guipúzcoa, and two sites subject to restoration, one in vizcaya and one in cantabria (fig. 1). values obtained for those geosites using the same procedure are: ratón de guetaria (fig. 3): vsgi = 0.86 coastal area of somorrostro: vsgi = 0.5 karst of cabárceno (fig. 4): vsgi = 0.9 expenditure on restoration for the latter two sites was respectively 3 ×106 € and 12 ×106 € (restoration actions also included non-geomorphic elements). both the “ratón de guetaria” and “karst of cabárceno” are widely known and very much appreciated by local population. the “coastal area of somorrostro”, on the other hand, is less known and not so much valued. that is, informal, subjective perception by local population is coherent with numerical values obtained using the procedure described. moreover, if effort devoted to restoration is used as an additional external indicator of “social appreciation”, we can see that expenditure in cabárceno (vsgi = 0.9) was considerably higher than in somorrostro (vsgi = 0.5). this is also reasonably coherent with the systematic evaluation described, although by no means should be considered as an objective measure of the sites’ value, due to the different cost factors involved in restoration. comparison between vsgi and actual expenditure on restoration provides the basis for a rough translation of the intangible “geosite value” into monetary units. from the figures provided above an average “theoretical value” of about 10 ×106 € can be assumed for an ideal site with vsgi = 1. this can in turn be used to express impact on geomorphosites or geosites in general, using reductions or increases in the dimensionless vsgi as well as the “theoretical monetary loss or gain” implied (bonachea et al., 2003). an example of this is shown in table 5. if monetary values indicated above are accepted, “theoretical losses” would be 3.7 ×106 € and 8.9 v.m. bruschi & a. cendrero fig. 2 distribution of geosites in the study area for the vergara-eibar motorway sector. distribuzione dei punti d’interesse geologico nella zona interessata dal tratto d’autostrada vergara-eibar. fig. 3 the “ratón de guetaria” (guetaria mouse), prominent geomorphological landmark in the region. il “ratón de guetaria” (topo di guetaria), punto d’interesse geomorfologico significativo della regione. ×106 € for alternatives a and b respectively. in brief, although criteria used to obtain vsgi will not necessarily be accepted by everyone and indicators used for “external validation” of the process have a certain degree of uncertainty, it appears that the procedure proposed represents a useful means to obtain, at least, a “coarse-grain” image of the quality of geomorphosites. 299geosite evaluation ... tab. 4 indicators and ranks for the value of each geosite (expression [3]; bonachea et al., 2003). indicators for which only three levels could be defined are marked with an asterisk (*). indicatori e ranghi definiti per il calcolo del valore definitivo di ogni punto d’interesse geomorfologico (espressione matematica [3]; bonachea et al., 2003). gli indicatori per i quali è stato possibile definire solo tre ranghi vengono segnalati con un asterisco (*). criteria indicators rank 4 well preserved; no visible degradation degree of 3 some degradation; damage to minor characteristics preservation degree of preservation 2 part of its characteristics degraded (c) 1 very affected by human activities, many of its characteristics degraded 0 total degradation; loss of the site’s character 4 only one example in the region relative abundance of 3 2 – 4 examples the site’s type 2 5 10 examples (a) 1 10 20 examples 0 > 20 examples diversity of 4 5 or more geological/ 3 4 geomorphological 2 3 elements 1 2(d) 0 only 1 4 > 90% of the greatest sgi of the same kind extent of the site 3 70 – 90% (e) 2 30 – 70% 1 10 – 30% 0 < 10% (*)value of site as 4 present, active processes clearly defined example of 2 erosion/accumulation features of present processes not clearly definedgeomorphological 0 fossil forms and/or deposits whose use for extrapolation of past processes is difficultprocesses (ex) 4 more than one ph.d thesis and numerous articles in refereed national and international journals degree of knowledge 3 at least one ph.d thesis and/or more than one article in refereed international about site journals and/or various in national journals (k) 2 some articles in refereed national journals and/or one article in an international journal 1 some brief notes in national journals or some articles in regional-local journal 0 no existing publications 4 5 types of activities types of activities that 3 4 types of activities can be carried out on site 2 3 types of activities (ac) 1 2 types of activities 0 1 types of activities (*) observation 4 public property of land, no limitations of access, no visual obstructions conditions 2 limitations of access or partial visual obstructions (o) 0 private property or view obstructed by fences, vegetation, etc. 4 good services within 4 km availability of services 3 good services within 45 km (s) 2 incomplete services within 5 km 1 good services within 10 km 0 absence of services within 10 km 4 > 100,000 inhab. in a radius of 25 km number of inhabitants 3 50 – 100,000 inhab. in a radius of 25 km in surrounding area 2 25 50,000 inhab. in a radius of 25 km (h) 1 10 25,000 inhab. in a radius of 25 km 0 < 10,000 inhab. in a radius of 25 km 4 direct access via national/regional roads accessibility 3 direct access via local roads (acc) 2 direct access via tracks 1 < 1 km from a vehicle path 0 > 1 km from a vehicle path potential for use (p) intrinsic quality (q) 3.2 geomorphosite identification and ranking the second case study concerns the application and comparison of criteria to be used for identification and selection of geomorphosites for an inventory in the province of cantabria (fig. 1). identification and selection of geomorphosites are highly subjective tasks, necessarily based on the experience of experts and their familiarity with the area. this is a generally accepted part of the process but it is convenient to analyse the degree of coincidence between different experts, the criteria implicitly or explicitly used for selection and the degree of internal coherence of individual experts’ assessment. in the case study described identification and assessment of sites was carried out in four types of geomorphic systems: coastal, glacial, fluvial and slope. the analysis was performed separately for each one of them, in order to deal with a more homogeneous population of objects and make comparisons easier. the initial step in the identification process was an e-mail questionnaire sent to 24 local experts, in which they were asked to indicate their personal degree of expertise on the different types of geomorphic environments as well as to provide a ranked list of at least 10 sites for each one of them (tab. 6). an “experts database” was elaborated with the 14 replies received. an initial classification of sites was directly derived from those replies, by simple addition of ranks assigned to each site by the different experts, the most important site having a value of 10 and the least important 1. theoretical values would thus rank from 140 (a site identified by all experts and considered by all of them as the most important within its category) to 1 (a site named by only one expert and considered as the least important of its group). obviously, the first case is unlikely to appear. a second e-mail questionnaire was then sent to experts, asking them to indicate, for the two types of geomorphic environments they considered themselves more familiar with, four criteria (ranked by order of importance) they considered relevant for geomorphosite value assessment. values between 1 (least important) and 4 (most important) were assigned and weights derived initially by simple addition, as explained before. weights were then reduced to a 0 – 1 scale (tabs. 7 and 8). the following step was the establishment, by the work team, of indicators that allow the identification of three levels or degrees for each criterion (tab. 9). three levels were used because they can be defined quite objectively. value of geomorphosites was then calculated separately for each category (glacial, coastal, fluvial, slope) using the expression: n vg = σ ci × wi i = 1 where: vg = value of geosite 300 v.m. bruschi & a. cendrero n º. s it e n a m e , s g i a e k e x d a c o s h a c c c q p v s g i (p re ) v s g i (p o st a ) v s g i (p o st b ) 1 m e g at u rb id it e s, s an l o re n zo 0 .8 0 0 .4 0 0 .4 0 0 .4 0 0 .0 0 0 .0 0 0 .8 0 0 .8 0 0 .6 0 0 .8 0 4 .0 0 2 .0 0 3 .0 0 0 .5 8 0 .5 8 0 .5 8 2 c re ta c e o u s f ly sc h , a ri st ib u ru 0 .8 0 0 .4 0 0 .4 0 0 .4 0 0 .0 0 0 .0 0 0 .8 0 0 .8 0 0 .6 0 0 .8 0 4 .0 0 2 .0 0 3 .0 0 0 .5 8 0 .5 8 0 .5 8 3 d an ia n m ar ls , s an l o re n zo 0 .8 0 0 .4 0 0 .4 0 0 .4 0 0 .0 0 0 .0 0 0 .8 0 0 .8 0 0 .6 0 0 .8 0 4 .0 0 2 .0 0 3 .0 0 0 .5 8 0 .5 8 0 .5 8 4 p ill o w -l av as , a rg at e 0 .8 0 0 .4 0 0 .4 0 0 .4 0 0 .2 0 0 .2 0 0 .0 0 0 .8 0 0 .6 0 0 .2 0 4 .0 0 2 .2 0 1 .8 0 0 .5 2 0 .5 2 0 .0 0 5 v o lc an ic r o c ks , a rz ab al e ta 0 .8 0 0 .4 0 0 .4 0 0 .4 0 0 .2 0 0 .0 0 0 .0 0 0 .8 0 0 .6 0 0 .0 0 4 .0 0 2 .2 0 1 .4 0 0 .4 8 0 .4 8 0 .4 8 6 v o lc an ic b o d ie s, i g ar at e 0 .8 0 0 .4 0 0 .4 0 0 .4 0 0 .0 0 0 .2 0 0 .4 0 0 .8 0 0 .6 0 0 .0 0 4 .0 0 2 .0 0 2 .0 0 0 .5 0 0 .5 0 0 .5 0 7 t ra c h yt e f lo w s, m al za g a 0 .8 0 0 .4 0 0 .4 0 0 .4 0 0 .4 0 0 .0 0 0 .8 0 0 .8 0 0 .6 0 0 .8 0 4 .0 0 2 .4 0 3 .0 0 0 .6 5 0 .3 0 0 .3 0 8 q u ar ry , m al za g a 0 .8 0 0 .4 0 0 .4 0 0 .4 0 0 .0 0 0 .4 0 0 .8 0 0 .8 0 0 .6 0 0 .8 0 4 .0 0 2 .0 0 3 .4 0 0 .6 1 0 .6 5 0 .6 5 9 f o ld , u rk o 0 .6 0 0 .4 0 0 .4 0 0 .4 0 0 .0 0 0 .2 0 0 .4 0 0 .8 0 0 .6 0 0 .4 0 4 .0 0 1 .8 0 2 .4 0 0 .5 0 0 .5 0 0 .5 0 1 0 f o ld s, e ib ar 0 .6 0 0 .4 0 0 .4 0 0 .4 0 0 .6 0 0 .2 0 0 .4 0 0 .8 0 0 .6 0 0 .4 0 4 .0 0 2 .4 0 2 .4 0 0 .6 0 0 .6 0 0 .6 0 1 1 p ill o w -b re c c ia s, l a a sc e n si ó n 0 .6 0 0 .4 0 0 .2 0 0 .4 0 0 .6 0 0 .2 0 0 .4 0 0 .8 0 0 .6 0 0 .4 0 4 .0 0 2 .2 0 2 .4 0 0 .5 6 0 .5 0 0 .5 0 1 2 t e c to n ic b re c c ia , u g ar ri ag a 0 .8 0 0 .4 0 0 .2 0 0 .4 0 0 .2 0 0 .2 0 0 .4 0 0 .8 0 0 .6 0 0 .4 0 4 .0 0 2 .0 0 2 .4 0 0 .5 3 0 .5 3 0 .5 3 1 3 c re ta c e o u s se c ti o n , a ra n e 0 .8 0 0 .4 0 0 .2 0 0 .4 0 0 .0 0 0 .2 0 0 .4 0 0 .8 0 0 .6 0 0 .4 0 4 .0 0 2 .0 0 2 .4 0 0 .5 3 0 .5 3 0 .5 3 1 4 p ill o w -b re c c ia s, p la c e n c ia 0 .6 0 0 .4 0 0 .2 0 0 .4 0 0 .6 0 0 .2 0 0 .4 0 0 .8 0 0 .6 0 0 .4 0 4 .0 0 2 .2 0 2 .4 0 0 .5 7 0 .5 7 0 .5 7 1 5 o u tc ro p , it u rb e 0 .8 0 0 .4 0 0 .2 0 0 .4 0 0 .0 0 0 .0 0 0 .4 0 0 .8 0 0 .6 0 0 .4 0 4 .0 0 1 .8 0 2 .2 0 0 .4 8 0 .4 8 0 .4 8 t o ta l v a lu e 8 .2 7 7 .9 0 7 .3 8 t a b . 5 i n d ic a to r va lu e s a n d v s g i fo r g e o si te s in t h e a re a o f th e v e rg a ra -e ib a r m o to rw a y se c to r. a : re la ti ve a b u n d a n c e ; e : e xt e n t; k : d e g re e o f kn o w le d g e ; e x: g o o d e xa m p le o f p ro c e ss e s; d : d iv e rs it y; a c : a c ti vi ti e s; o : o b se rv a ti o n c o n d it io n s; s : a va ila b ili ty o f se rv ic e s; h : n u m b e r o f in h a b it a n ts ; a c c : a c c e ss ib ili ty ; c : st a te o f c o n se rv a ti o n ; q : q u a lit y s g i; p : p o te n ti a l fo r u se ; v s g i (p re ): va lu e o f s g i b e fo re m o to rw a y c o n st ru c ti o n , v s g i (p o st a , b ): va lu e o f s g i a ft e r m o to rw a y c o n st ru c ti o n ( a lt e rn a ti ve s a a n d b ). in d ic at o ri e v s g i p e r i p u n ti d ’in te re ss e g e o lo g ic o n e lle z o n a in te re ss at a d al s e tt o re d ’a u to st ra d a v e rg ar ae ib ar n a. a : ab b o n d an za r e la ti va ; e : e st e n si o n e ; k : g ra d o d i c o n o sc e n za ; e x: b u o n e se m p io d i p ro c e ss o ; d : d iv e rs it à; a c : at ti vi tà ; o : c o n d iz io n i d ’o ss e rv az io n e ; s : p re se n za d i se rv iz i; h : n u m e ro d i ab it an ti ; a c c : ac c e ss ib ili tà ; c : st at o d e lla c o n se rv az io n e ; q : q u al it à d e l p u n to d ’in te re ss e g e o lo g ic o ; p : p o te n zi al e d ’u so ; v s g i (p re ): va lo re d e l p u n to d ’in te re ss e g e o lo g ic o p ri m a d e lla c o st ru zi o n e d e ll’ au to st ra d a; v s g i (p o st a , b ): va lo re d e l p u n to d ’in te re ss e g e o lo g ic o d o p o l a c o st ru zi o n e d e ll’ au to st ra d a (a lt e rn at iv e a e b ). 301geosite evaluation ... tab. 6 questionnaire sent to experts. scheda usata per il primo questionario proposto agli esperti. ci = value of criterion in site (in the three-term scale) wi = weight of criterion i values thus obtained are shown in table 10. a comparison was then made between the rank of geosites obtained directly from the initial evaluation by all experts and the one derived from the application of the expression above. table 11 shows the results obtained for coastal sites. the agreement between both ranks is very good for sites at the top of the scale (figs. 5, 6) and less satisfactory at lower levels, although the difference never exceeds 3 positions in the rank. table 12 presents a comparison between the ranks proposed by one individual expert and the same vg values of table 11. differences, as should be expected, are greater. more or less the same trend was observed when other individual assessments were compared with the vg rank. finally, in table 13 a comparison is presented between the rank initially proposed by one expert and vg obtained using the criteria proposed by that same expert. again, agreement is good at the top of the scale and not so good at lower levels. in this case the agreement is even better than in the other two examples, a logical result considering that we are comparing an expert with himself. however, it is clear that there is a certain inconsistency between the initial synoptic assessment and the one derived from the application of the criteria proposed by the same person. in the other words, when providing the overall assessment of sites the expert does not appear to be using exactly the same criteria he considers important for site evaluation. 4. final comments the examples above show that the analytical procedure described for the evaluation of geomorphosites provides results that are coherent with independent assessments. 302 v.m. bruschi & a. cendrero fig. 4 kárst of “cabárceno”. paesaggio carsico di “cabárceno”. fig. 5 dunes of liencres. sistema dunare di liencres. tab. 7 identification of sgi quality criteria. identificazione dei criteri di qualità per i punti d’interesse geomorfologico. expert no. criteria 1 2 3 4 5 6 is it inventoried? 4 state of conservation 3 4 illustrates active processes 2 3 3 2 3 size 3 2 4 4 4 related to human issues 2 2 2 good example of geomorph. evolution 1 4 3 observation conditions 1 1 1 1 1 that is, the “geomorphosite quality models” proposed can be used to obtain rankings of sites that coincide reasonably well with other, independent “value indicators”. this is the case forinformal appreciation of sites by the general public or expenditure on site rehabilitation. both can be considered as indicators of the value attached to those sites by society. results obtained with the analytical procedure also provide a reasonable coincidence with the subjective evaluation by groups of experts. the agreement is particularly good when high value sites are considered. nevertheless, a certain degree of inconsistency has been observed when it comes to compare what an 303geosite evaluation ... fig. 6 estuary of “san vicente de la barquera”. estuario di san vicente de la barquera. tab. 8 determination of weights for criteria in table 7. determinazione dei pesi per i criteri della tabella 7. criteria σς weight size 17 0.28 illustrates active processes 13 0.22 state of conservation 7 0.12 good example of geomorph. evolution 8 0.13 related to human issues 6 0.10 observation conditions 5 0.08 is it inventoried? 4 0.07 tab. 9 criteria ranks ( t h r e e t e r m scale). ranghi definiti per ogni criterio selezionato (scala a tre termini). 3 > 1.000.000 m2 a 2 10.000 – 1.000.000 size 1 < 10.000 m2 b 3 very active, clearly visible illustrates active processes 2 moderately active 1 inactive or barely visible c 3 perfectly preserved, no damage state of conservation 2 partly damaged but main features remain 1 very damaged d 3 main elements for interpreting geomorphological evolution present good example of 2 some features useful for interpreting geomorphological evolution geomorphological evolution 1 very limited or no possibility to interpret past evolution e 3 processes/features directly relevant for human activities related to human issues 2 possible implication with human activities 1 not relevant for human activities f 3 complete access and visibility observation conditions 2 some limitations for access/visibility 1 great difficulty for observation due to physical barriers g 3 in national inventory is it inventoried? 2 in local/regional inventories 1 non inventoried expert considers “should be important” (criteria) with what he “actually values as important” (direct ranking of sites). this type of inconsistency would probably be reduced if an iterative procedure, such as the delphi method, were used (balkey, 1969). in summary, the approach presented makes the procedure transparent, expressing criteria used in clear, unequivocal terms. those criteria are represented by the values (rank, points) for the different conditions each indicator can present as well as their weights (relative importance of indicators). the “quality models” used are based on a series of simple-to-assess categorical variables. results obtained using those models can therefore be replicated by any operator (provided the same criteria are accepted), thus significantly reducing the degree of subjectivity in the evaluation process. as the models provide results in numerical form, validation through comparison with independent assessments or indicators is greatly facilitated. total vsgi or other qualities such as “intrinsic quality”, “potential for use” o “protection need” can thus be represented by numerical values. this numbers do not strictly represent a measure, because they correspond to dimensionless indices, but can be considered as “point values” or “positions in a rank”. going back to the initial question presented in the title, the approached proposed provides a means to roughly “measure” some intangible geomorphosite values. nevertheless, the procedure needs to be improved, refined and more thoroughly validated. 304 tab. 10 value of coastal geomorphosites in cantabria. values in brackets correspond to criteria weights. valori definitivi dei punti d’interesse geomorfologico appartenenti al sistema costiero della cantabria. i valori fra parentesi corrispondono ai pesi definiti per i criteri. criteria a b c d e f g vg site (0.28) (0.22) (0.12) (0.13) (0.10) (0.08) (0.07) ría de s.v. da la barquera 3 3 2 2 2 3 2 2.58 puntal de somo 3 2 2 2 2 3 2 2.36 ría de ajo 3 3 2 1 1 1 1 2.12 ría de t. menor 3 2 2 2 1 2 2 2.18 dunas de liencres 3 3 2 3 2 3 2 2.71 punta dichoso 2 3 2 1 2 2 2 2.09 plat. abrasión de la arnía 1 3 3 3 3 3 1 2.30 dunas de oyambre 2 3 1 3 2 2 2 2.23 rasas de t. mayor 3 1 3 3 1 3 2 2.29 dunas de sonabia 1 2 3 3 1 3 1 1.98 tab. 11 comparison between initial rank and vg (all experts). comparazione tra i valori iniziali (sondaggio) ed i valori ottenuti applicando il modello di qualità (vg). v.m. bruschi & a. cendrero acknowledgements support for this work was provided by the “fundación marcelino botín” (grant to viola maria bruschi) and project gets (contract erbfmr ct970162, tmr programme, european commission). references balkey n.c. (1969) the delphi method: an experimental study of group opinion the rand corp., santa monica, california. bonachea pico j., bruschi v.m., remondo j., gonzález305 tab. 12 comparison between initial rank (exp. nº. 14) and vg (all experts). comparazione tra i valori iniziali (sondaggio di un solo esperto, il nº 14) ed i valori ottenuti applicando il modello di qualità (vg). tab. 13 comparison between initial rank (exp. nº. 1) and vg (criteria of exp. nº. 1). comparazione tra i valori iniziali (sondaggio di un solo esperto, il nº 1) ed i valori ottenuti applicando il modello di qualità ed i criteri definiti dal medesimo esperto (vg). geosite evaluation ... díez a., salas l., bertens j., cendrero a., otero c., giusti c., fabbri a., ganzález-lastra j.r. & aramburu j.m. (2003) an approach for the incorporation of geomorphologic factors into eia of transportation infrastructures; a case study in northern spain geomorphology (accepted, 2003). cendrero a. (2000) patrimonio geológico; diagnóstico, clasificación y valoración in: jornadas sobre patrimonio geológico y desarrollo sostenible. ministerio de medio ambiente, serie monografías, pp. 23-37. martini g. (2000) patrimonio geológico y geoturismo in: d. barettino, w.a.p. wimbledon, e. gallego (eds), patrimonio geologico: conservación y gestión., pp. 161 170. mohr l.b. (1988) impact analysis for program evaluation pacific grove, brooks & cole, california. panizza m. & piacente s. (1999) il concetto di “bene” nel paesaggio fisico in: m. bertacchini, c. giusti, m. marchetti, m. panizza & m. pellegrini (eds.), i beni geologici della provincia di modena, artioli editore, modena, pp. 8-9. p oli g. (1999) geositi testimoni del tempo. fondamenti per la conservazione del patrimonio geologico collana naturalistica del servizio paesaggi, parchi e patrimonio naturale, regione emilia romagna, 264 pp. reynard e., holzman c., guex d., summermatter n. (2002) géomorphologie et tourisme actes de la réunion annuelle de la societé de géomorphologie (ssgm), 21 23 september 2001, finhaut, lausanne. institut de gèographie, travaux et recherches. 24, pp. 1 10. rivas v., rix k., frances e., cendrero a., brunsden d. (1997) geomorphological indicators for environmental impact assessment; consumable and nonconsumable geomorphological resources geomorphology. 18 (3-4), pp. 169-182. 306 v.m. bruschi & a. cendrero imp.derita evoluzione pleistocenica del margine tirrenico dell’italia centrale tra eustatismo, vulcanismo e tettonica donatella de rita, marina fabbri & corrado cimarelli dp.to scienze geologiche, università degli studi roma3, l.go san leonardo murialdo 1, 00146 roma e-mail derita@uniroma3.it riassunto: de rita d. et al., evoluzione pleistocenica del margine tirrenico dell’italia centrale tra eustatismo, vulcanismo e tettonica. (it issn 0394-3356, 2004). viene presentata una sintesi dei dati ottenuti durante la realizzazione dei fogli geologici alla scala 1:50.000 riguardanti alcune aree costiere del lazio. la possibilità di porre a confronto l’evoluzione di settori che presentano problematiche simili ma con situazioni locali specifiche ha permesso di evidenziare, a partire da circa 850 ka, una storia comune per la costa del lazio settentrionale e centrale, diversa da quella che ha invece interessato nello stesso intervallo di tempo la costa del lazio meridionale. la ricostruzione degli eventi a scala regionale ha permesso di distinguere gli effetti di una tettonica regionale (soprattutto di sollevamento isostatico lungo la costa del lazio settentrionale e centrale e di subsidenza per quello meridionale) rispetto a movimenti locali che potrebbero essere essenzialmente legati alle fasi vulcaniche che hanno contemporaneamente interessato il margine tirrenico del lazio. vengono inoltre evidenziate alcune problematiche che riguardano l’organizzazione cartografica nazionale ed in particolare la denominazione dei sintemi a scala regionale e la necessità di introdurre una nomenclatura in grado di associare nel suo interno più sintemi non distinguibili sul terreno. abstract: de rita d. et al., the evolution of the tyrrhenian margin of central italy: the interplay between volcanism, eustatism and tectonciv events). (it issn 0394-3356, 2004). we present a synthesis of the data collected during the field work devoted to the realization of the geological map at the 1:50.000 of italy, concerning some coastal areas of latium. the possibility to compare the evolution of areas envolved in the same geodinamic contest but having different local structural framework, has allowed us to evidence a common history, starting from 850 ka, for the coast of northern and central latium , different from that of the southern coast. the effect of local estensional tectonic related to the volcanism which interested central italy in that period was distinguished. the units have been organized in unconformity bounded stratigraphic units (ubsu) on the base of the hierarchy order of the basal surfaces delimithing them. synthemes have been limited by surfaces recognized at regional scale caused by oscillation of the sea level. each surface has been dated on the base of the geochronological data and /or the faunistic content of the above sediments and then it has been correlated to an isotopic stage. the vulcanic units have been organized following the indication of fisher and schmincke (1984), by introducing the eruption units. “an eruption unit is a deposit defined as a thickness of volcanic material deposited from an eruptive pulse, an eruptive phase or an eruption…it is a conceptual entity that relates volcanic activity and a rock stratigraphic unit”. this method allows to consider all the unconformities recognizable in volcanic areas which cannot be extended at regional scale but are important to reconstruct the main phases of the volcano evolution. it allows even to consider the volcanic evolution in its regional contest. the volcanic deposits originated by the reworking of the primary units have been distinguished in syn-eruption and inter-eruption units (smith, 1991; de rita et alii, 2002 b; giordano et alii, 2002 a). the geological and structural evolution of the island of ponza, zannone and palmarola in the pontine archipelago, 30 km south east from the central coast of latium, has been reconstructed. these three islands are the remnants of a submarine dome complex developed from the upper pliocene to almost 1.1 ma. three main ryolithic domes have been recognized in ponza, developed along ne-trending lineaments and showing different hyaloclastic facies reflecting the different geological contest in which they developed. the norhernmost piana d’incenso dome shows a prevailing hyaloclastic facies made of clast supported breccias and by flow banded lavas produced by its intrusive mode of emplacement, as a cryptodome. similar facies characterize the zannone dome in the zannone island, where the intrusive nature is demonstrated by the structural relationship between the flow-banded lavas and the sedimentary units: these are tilted and deformed along low angle normal faults at the contact with the vulcanites. we have interpreted that the domes emplaced as cryptodome, because they were intruded almost at the center of a structural high of the sedimentary substratum made of the mesozoiccenozoic brittle rocks. the other domes of ponza and palmarola show different hyaloclastic facies, mainly made of thick hyaloclastites showing different degree of brecciation reflecting the different degree of magma-water interaction. we suggest that the extrusive mode of emplacement of these domes is because their emplacement was along regional extensional faults controlling the structural evolution of the continental platform on which the volcanic dome complex developed. in the southern part of ponza a subaerial trachytic dome developed almost 1.1 ma, after that the rhyolitic volcanism ended. the geological gap between the rhyolitic and the trachytic phases of volcanism, is evidenced by a high relief erosive surface. on the three island, in the range between 80 and 110 m a.s.l., marine terraces are present. these terraces have been correlated on the base of their similar morphology and because the above sediments are lithologically similar. they have to be formed after the end of the volcanism in the three islands. the uplifting of the surface occurred probably during a contemporaneous relative low standing of the sea level. we suggest to relate this event with the uplifting of the central coast of latium, that occurred between 0.9 and 0.8 ma, during the isotopic stage 22, when the alkali-potasssic volcanism started. the difference of the altitude at which the surface presently lies, is probably due to the effect of local extensional tectonic. along the northern and the central coast of latium, we have recognized three orders of terraces which coincide in the altitude and the age. in the northern coast the presence of a small basin infilled by volcaniclastic sediments, was helpful in correlating stratigraphic succession of the vulsini, sabatini and vico volcanic districts to the coastal area successions. here, the ubsu have been organized in 5 synthemes whose basal surfaces were produced during low standing of the sea level. on the base of geochronological data and /or the faunistic content of the above sediments, the last three synthems have been ascribed to the 9,7 and 5 isotopic stages respectively (de rita et alii 2002 b). in the central coast of italy, in the area of roma city, the ubsu have been organized in 7 synthemes (giordano et alii 2003), the last three of which have the same altitude and age of those recognized along the northern coast. along the southern coast no terraces can be recognized. it has been then possible to establish that the coast of central italy was subjected to a regional uplift evaluated in the order of 0,2 mm/y, whereas the southern coast was subjected to a continuous subsidence active from pliocene. local extensional tectonic related to the volcanism has been recognized in the roman area. some problems related to the organization of the national cartography are evidenced. they concern the nomenclature of synthem at regional scale and the opportunity to introduce a specific hierarchy to indicate an association of synthemes. in fact, in some cases it has not been possible to recognize all the discontinuities related to sea level oscillations, precluding the possibility to distinguish single synthemes that have been unified together. they do not represent a supersynthem because unconformities of major hierachic order were not recognized. parole chiave: tettonica, vulcanismo, pleistocene, eustatismo, margine tirrenico, italia centrale. keywords: tectonics, volcanism, pleistocene, eustatism, tyrrhenian margin, central italy. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 523-536 524 d. de rita, m. fabbri & c. cimarelli introduzione nel pleistocene, l’evoluzione del margine tirrenico dell’italia centrale è stata determinata da più fattori: da una parte gli effetti della tettonica estensionale post orogenica che in quest’epoca raggiunge il suo acme con conseguente sviluppo del processo vulcanico relativo alla nascita del bacino tirrenico, dall’altra le oscillazioni glacio-eustatiche del livello del mare. la complessità degli eventi è stata analizzata e discussa in più lavori la cui attenzione è via via focalizzata ora su un tema ora su un altro. manca, tuttavia, a tutt’oggi un quadro d’insieme degli eventi in cui sia stato valutato il ruolo dei vari fattori. questa nota si propone di dare un contributo alla risoluzione del problema, illustrando i risultati ottenuti durante la realizzazione di più fogli geologici alla scala 1:50.000, (progetto carg). il lavoro di cartografia di dettaglio di più aree costiere, comprese tra il lazio settentrionale e quello meridionale (fig. 1), ha infatti offerto la possibilità di porre a confronto l’evoluzione di settori che presentano problematiche simili ma con situazioni locali specifiche. l’obiettivo cartografico ha portato alla messa a punto di nuove tecniche di analisi di terreno in grado di consentire correlazioni significative alla scala regionale. questo, insieme all’approccio interdisciplinare, è stato di grande ausilio, permettendo di inquadrare i processi vulcanici nell’ambito dell’evoluzione regionale e di valutare gli effetti della tettonica distensiva sia a scala regionale sia locale. e’ stato infine possibile effettuare una valutazione quantitativa dei tassi di sollevamento che le regioni costiere del lazio hanno subito negli ultimi 300 ka. in base alla gerarchizzazione delle superfici che le delimitano, le unità sono state organizzate in unità stratigrafiche a limiti inconformi (ubsu; salvador, 1987a, b). i sintemi sono definiti da superfici riconosciute a livello regionale e legate alle oscillazioni del livello del mare. per le unità vulcaniche, tenendo conto delle differenze sia temporali che di estensione dei processi che avvengono in ambito vulcanico rispetto a quelli caratterizzanti l’ambiente sedimentario costiero, si è preferito mantenere una nomenclatura separata e un’organizzazione stratigrafica legata alla storia evolutiva del vulcano, in cui le superfici di discontinuità identificate possono o meno coincidere con quelle riconosciute a livello regionale (de rita et alii, 2000). i depositi originatisi dal rimaneggiamento delle unità vulcaniche sono stati analizzati in termini di unità sin-eruttive ed inter-eruttive (smith,1991; de rita et alii, 2002b; giordano et alii, 2002a ) i sintemi sono stati datati sulla base di dati geocronologici e/o paleontologici e correlati alla scala degli isotopi dell’ossigeno (shackleton et alii, 1990; shackleton, 1995). nei primi paragrafi viene presentata una sintesi dei dati più significativi ottenuti nelle aree studiate che sono: le isole pontine settentrionali, l’area costiera del l a z i o s e t t e n t r i o n a l e a l c o n f i n e c o n l a t o s c a n a (montalto di castro-tarquinia), l’area costiera romana (tra la città di roma ed ardea), il settore sud occidentale del vulcano di roccamfina (fig. 1). in un secondo paragrafo saranno evidenziate le correlazioni e la valutazione degli effetti della tettonica regionale rispetto a quella locale. saranno, inoltre, discusse alcune problematiche inerenti la cartografia nazionale in ambito vulcanico. fig. 1 ubicazione dei settori analizzati lungo la costa tirrenica dell’italia centrale. location of the analyzed sectors along the tyrrhenian coast of central italy. area delle pontine settentrionali e’ stata ricostruita l’evoluzione geologico-strutturale delle isole di ponza, zannone e palmarola, facenti 525evoluzione pleistocenica del margine ... parte del foglio borgo grappa (de rita et alii, in stampa). le tre isole, insieme a ventotene e santo stefano fanno parte dell’arcipelago pontino localizzato a circa 30 km dalla costa dell’italia centrale a sud del circeo (fig. 1). fig. 2 (a) dem delle isole pontine settentrionali. 1) domi. 2) faglia presunta (per la spiegazione vedi il testo). (modificato da de rita et alii, 2001). (b) carta geologica schematica delle isole pontine settentrionali. 1) unità sedimentarie meso-cenozoiche. 2) unità sedimentarie plio-quaternarie. 3) lave riolitiche in dicchi. 4) facies ialoclastica clasto sostenuta. 5) facies ialoclastica matrice sostenuta. 6) prodotti trachitici del domo di m. la guardia. 7) ubicazione dei terrazzi marini. (a) dem of the northern pontine islands. 1) domes. 2) inferred fault (for explanation, see text). (modified from de rita et alii, 2001). (b) schematic geological map of the northern pontine islands. 1) mesozoic-cenozoic sedimentary units. 2) pliocene-quaternary sedimentary units. 3) rhyolitic coherent lava dikes. 4) clast-supported hyaloclastic breccia. 5) matrice-supported hyaloclastic breccia. 6) mt. la guardia dome trachytic products. 7) ubications of marine terraces. 526 le isole giacciono sulla piattaforma continentale tirrenica il cui assetto strutturale è molto simile a quello dell’appennino centrale, costituito, cioè, da unità di thrust mio-plioceniche, disarticolate in una serie di alti e bassi strutturali dalla tettonica estensionale post-orogenica relativa all’evoluzione plio-pleistocenica del bacino tirrenico (zitellini et alii, 1984). le tre isole sono costituite dai resti di un complesso di domi riolitici sottomarini che mostrano una grande variazioni di facies ialoclastiche, da finemente brecciate matrice sostenute a clasto sostenute coerenti, fino a lave coerenti in dicco, connesse al diverso grado di frammentazione subito dal magma al contatto con l'acqua (carmassi et alii, 1983; scutter et alii, 1998; de rita et alii, 2001). nel caso dell’isola di ponza il processo eruttivo da sottomarino divenne subaereo, con un corrispondente cambio di chimismo dei magmi da riolitici a trachitici. nel corso del rilevamento, in base alla natura dei componenti dei depositi ed in base alle correlazioni stratigrafiche si è potuto stabilire che tutti i depositi affioranti nella parte meridionale dell’isola di ponza, poggianti sulle facies ialoclastiche e costituiti da unità di surges, di colata piroclastica e domi lavici, provengono da un unico centro localizzato nell’area di monte la guardia (fig. 2). la loro sequenza stratigrafica illustra le varie fasi di crescita del domo trachitico (de rita et alii, in stampa). oltre al domo finale trachitico di monte la guardia, sull’isola di ponza sono stati riconosciuti altri tre domi riolitici principali: uno in corrispondenza di monte pagliaro, due coalescenti tra loro nell’area di cala dell’acqua ed un terzo nella parte più settentrionale di piana d’incenso (fig. 2). nell’isola di palmarola sono stati identificati almeno tre domi riolitici: uno nella parte settentrionale con centro in corrispondenza di monte tramontana e due coalescenti nella parte meridionale con centro a mare lungo la costa occidentale dell’isola (fig. 2). a zannone è stato identificato un unico domo che comprende la totalità degli affioramenti vulcanici dell’isola (fig. 2). particolare attenzione è stata dedicata ai rapporti strutturali tra le unità vulcaniche e sedimentarie. infatti a zannone lungo la costa settentrionale affiorano unità sedimentarie dal paleozoico al mesozoico con rapporti strutturali complessi variamente interpretati dagli autori (segre, 1952, 1953; parotto & praturlon, 1975). il rilevamento ha permesso di stabilire che i contatti strutturali tra le unità sedimentarie sono superfici a basso angolo determinate dallo scollamento lungo piani debolmente inclinati prodotti dalla spinta di crescita del domo di zannone (fig. 3). tale domo deve essersi messo in posto con modalità tipo criptodomo, al contatto tra il flysch e le unità carbonatiche sottostanti. questa ipotesi è anche supportata dalle facies ialoclastiche del domo che presentano un basso grado di autobrecciazione e un alto grado di coerenza. le stesse facies ialoclastiche caratterizzano il domo di piana d’incenso nella parte più settentrionale di ponza. interessante sottolineare che un dragaggio effettuato poco a largo della costa occidentale dell’isola ha incontrato a circa 30 m di profondità rocce calcareo-dolomitiche (martorelli et alii, 2003), confermando così la presenza di un alto strutturale del basamento prevulcanico già evidenziato da un sondaggio (savelli, 1943) e da dati gravimetrici, nel settore settentrionale dell’isola di ponza (carmassi et alii, 1983; bellucci et alii, 1997). l’alto strutturale si estenderebbe fino all’isola di zannonne dove le rocce calcareo-dolomitiche costituiscono la falesia settentrionale dell’isola. questo dato permette di stabilire che i domi di zannone e piana d’incenso si sono messi in posto come criptofig.3 schema dei rapporti stratigrafici e strutturali dell’isola di zannone. 1) arenarie e filliti permo-triassiche. 2) dolomie triassiche. 3) calcari, marne e arenarie cretacico-mioceniche. 4) argille messiniane. 5) lave riolitiche in dicchi. 6) facies ialoclastica clasto sostenuta. le frecce indicano i piani di scivolamento gravitativo prodotti dalla messa in posto del domo. stritigraphic and structural scheme of zannone island (not to scale). 1) permian-triassic sandstones and phyllites. 2) triassic dolomites. 3) cretaceous-miocene limestones, marls and sandstones. 4) messinian clays. 5) rhyolitic lava dikes. 6) clast-supported hyaloclastic breccia. arrows indicate low angle slide planes due to dome emplacement. d. de rita, m. fabbri & c. cimarelli 527 domi a differenza degli altri domi costituenti le isole di ponza e palmarola che per le caratteristiche delle facies ialoclastiche possono essere considerati domi estrusivi. la modalità di messa in posto come criptodomi o domi esogeni può essere determinata dal contesto strutturale in cui i magmi risalgono in superficie ed in particolare dalla presenza o meno di faglie regionali (cimarelli et alii, 2003). l’età di messa in posto dei domi sottomarini è posteriore al pliocene superiore. infatti, a palmarola sono presenti depositi argillosi, attribuiti al pliocene superiore per la presenza di globorotalia inflata (carrara et alii, 1986), in accordo con le datazioni radiometriche effettuate sulle lave del dicco di monte tramontana, che lo datano a circa 1.6 ma (barberi et alii, 1967). il domo trachitico di monte la guardia ha un’età di circa 1.1 ma (barberi et alii 1967; savelli 1983, 1987; bellucci et alii, 1999). durante l’intervallo di tempo intercorso tra la messa in posto delle vulcaniti sottomarine e le successive unità esplosive del domo trachitico di monte la guardia deve essersi verificato un concomitante fenomeno di sollevamento dell'isola e ritiro del livello del mare. questi eventi hanno prodotto le profonde incisioni vallive visibili nel settore meridionale dell’isola di ponza, successivamente colmate dai prodotti esplosivi e dai depositi del loro rimaneggiamento. tali incisioni erano state precedentemente interpretate come residui di centri idromagmatici (carmassi et alii, 1983; de rita et alii, 1986; vezzoli, 1988; bellucci et alii, 1997, 1999). su tutte e tre le isole tra le quote 80 e 120 m s.l.m., sono presenti depositi terrazzati già riconosciuti e riferiti a momenti diversi di stazionamento del livello del mare (segre, 1952, 1953; barberi et alii, 1967; vezzoli, 1988; carrara et alii 1993, 1994; bellucci et alii, 1997, 1999). questi terrazzi sono invece stati correlati tra loro per evidenze morfologiche e per la similitudine litologica dei depositi e riferiti ad un intervallo di tempo successivo all’attività vulcanica delle tre isole. un affioramento estremamente significativo è quello presente sulla falesia sudorientale di monte la guardia, nel settore meridionale di ponza (fig. 4). in questa località è ben visibile l'appoggio della superficie di terrazzamento su due delle unità piroclastiche trachitiche (unità 2 e 3 della fig. 4) che accompagnano la messa in posto del domo. l’unità piroclastica 3 è all’interno di un canale esposto nella sua integrità. inoltre i dati di terreno indicano che, durante l'attività iniziale del domo di monte la guardia, il livello del mare stazionava più o meno alla quota di affioramento dei depositi relativi che sono di natura idromagmatica, o sono flussi detritici ad alta concentrazione arrivati in acqua. il sollevamento della superficie deve essersi verificato per un processo di uplift continentale concomitante al ritiro del mare. collocare temporalmente questi fig. 4 appoggio del terrazzo marino (5) sulle unità piroclastiche trachitiche (1,2,3,4) del domo di m. la guardia. marine terrace deposit (5) laying on the mt. la guardia trachytic pyroclastic units (1,2, 3,4) evoluzione pleistocenica del margine ... 528 eventi risulta pressoché impossibile. dopo 1.1 ma, lungo la costa tirrenica una superficie di erosione che testimonia un evento di sollevamento regionale concomitante ad un momento di basso stazionamento del livello del mare è posta in correlazione con lo stadio isotopico 22, tra 0.9 e 0.8 ma e potrebbe essere relativa alla risalita dei magmi responsabili del vulcanismo alcalino-potassico del lazio. in tal caso, la superficie potrebbe coincidere con la base delle unità di san marcello e di ponte galeria, rispettivamente lungo la costa settentrionale e centrale del lazio. le differenze in quota della superficie riscontrata sulle tre isole possono essere spiegate da processi tettonici di sollevamento e basculamento che diversi autori hanno già segnalato (carrara et alii, 1993, 1994) e che possono aver svincolato le tre isole tra loro o anche singoli settori delle stesse. ad esempio è possibile ipotizzare un importante svincolo strutturale che limiti da una parte le isole di zannone, palmarola ed il settore settentrionale di ponza rispetto al settore meridionale che risulterebbe maggiormente ribassato. tale lineamento strutturale avrebbe una direzione circa nesw ed insisterebbe sull’area di forte alterazione idrotermale nel settore settentrionale di ponza (area di cava in località cala dell'acqua) e di gavi (fig. 2).un discorso a parte merita la superficie sub pianeggiante e debolmente inclinata verso mare, presente a piano d’incenso nel settore settentrionale di ponza e precedentemente interpretata come superficie di abrasione marina (carrara et alii , 1994). la definizione dei processi vulcanici ha consentito di porre l’accento sulla necessità di distinguere la geometria delle superfici che vengono prese in considerazione in relazione al loro sviluppo in ambito vulcanico. ad esempio, nel caso di corpi intrusivi subsuperficiali di tipo criptodomo, superfici piane debolmente inclinate vengono prodotte dallo stesso processo di risalita del corpo intrusivo e non indicano necessariamente la presenza di un terrazzo marino, a meno del ritrovamento in situ dei sedimenti relativi. gli unici depositi presenti al di sopra della superficie di piano d’incenso sono delle argille che derivano dal processo di alterazione della lava sottostante (de rita et alii, 2003). inoltre, il sollevamento locale dovuto alla risalita a giorno del corpo intrusivo può essere responsabile della formazione di una serie di terrazzi basculati che non necessariamente indicano ordini di terrazzi successivi relazionabili alle oscillazioni del livello del mare. area costiera del lazio settentrionale tra tarquinia e montalto di castro questo settore costiero del lazio settentrionale (fig. 1) ha offerto l’opportunità di analizzare i rapporti tra vulcanismo e sedimentazione costiera, tenendo conto delle variazioni del livello del mare occorse durante il quaternario. a questo scopo è stata determinante l’analisi dei depositi vulcanoclastici di un piccolo bacino sedimentario, bacino di tuscania, collocato tra l’area costiera e la periferia dei distretti vulcanici dei vulsini, di vico e dei sabatini a oriente, che si configura per un lungo periodo come parte dell’apron (sensu smith, 1991) dei vulcani stessi (de rita et alii, 2002). le correlazioni hanno tenuto conto del fatto che il settore costiero del lazio settentrionale è un’area di relativa stabilità tettonica (de rita et alii, 2002). la presenza di depositi terrazzati di origine marina è stata oggetto di approfonditi studi (bonadonna, 1967; alberti et alii, 1970; fazzini et alii, 1972; ambrosetti et alii, 1978, 1981; conato & dai pra, 1980; radtke et alii, 1982; radtke, 1983; bartolini & bosi, 1983; bartolini et alii, 1984; hearty & dai pra, 1986a, b; hearty, 1986; bosi et alii, 1990; messina et alii, 1990; palieri et alii, 1990). i sedimenti più antichi del pleistocene inferiore p.p. sono stati inclusi in un unico supersintema (supersintema monte riccio) in quanto la superficie inferiore è molto articolata lasciando ipotizzare una frammentazione di ambienti imputabile ad una fase tettonica. all’interno del supersintema le unità litostratigrafiche non sono state organizzate in sintemi per l’impossibilità di correlare superfici relative alle oscillazioni del livello del mare tra affioramenti piccoli e discontinui. i depositi costieri e vulcanoclastici relativi al pleistocene inferiore p.p.-pleistocene superiore sono stati organizzati all’interno di 5 sintemi correlati agli stadi isotopici attraverso datazioni geocronologiche e/o associazioni faunistiche (fig. 6). le caratteristiche di facies dei depositi costieri più antichi, organizzati in almeno tre terrazzi marini sviluppati parallelamente alla costa attuale e compresi nel sintema di s. marcello, testimoniano il processo di emersione dell’area avvenuto circa 850 ka fa le prime unità vulcaniche alcalino-potassiche che raggiungono l’area sono comprese nel successivo sintema biedano tra gli stages isotopici 15 e 11. si tratta di unità ignimbritiche provenienti dal centro del paleobolsena (nappi, 1985), datate intorno ai 491±9 ka (villa in funiciello et alii, in stampa), a cui si associa una unità ignimbritica sabatina (rosa, 1995) datata a 433 ± 6 ka (cioni, 1993). nell’area relativa al bacino di tuscania al si sopra delle ignimbriti basali è presente una successione complessa costituita da depositi relativi a flussi iperconcentrati e a debris flow (smith, 1991), a cui si intercalano nella parte alta depositi fluviali e più raramente palustri e lacustri. sono inoltre presenti livelli di ricaduta provenienti dal vulcano di vico, fra cui vico α (cioni et alii, 1987) datato a 419 ±1.5 ka (laurenzi & villa, 1987), e colate di lava vicane. non sono stati rinvenuti in affioramento depositi marini costieri relativi a questo sintema. la mancanza di tali depositi fa ipotizzare che in quel momento la costa fosse più arretrata rispetto all’attuale. l’ipotesi potrebbe essere supportata dalla segnalazione di depositi correlabili, attualmente sommersi (chiocci in de rita et alii, 2002 b) la sedimentazione nel bacino di tuscania continua fino allo stadio isotopico 9, con la deposizione di sedimenti in facies prevalentemente fluviale, lacustre e palustre, in cui si intercalano livelli di ricaduta pliniana e stromboliana e colate di lave di provenienza vicana e vulsina; gli ultimi 12 metri sono fortemente cementati da cemento travertinoso. quindi, l’apporto vulcaniclastico all’interno del bacino diminuisce notevolmente. infatti la geometria e la distribuzione dei depositi relativi allo stadio isotopico 7, che affiorano in terrazzi discontinui lungo i corsi d’acqua principali, indicano che il bacino di tuscania è totalmente riempito. i depositi costieri d. de rita, m. fabbri & c. cimarelli relativi al sintema archi di pontecchio (stadio isotopico 7) hanno al tetto un deposito vulcanico relativo all’attività del centro di latera datato tra i 190 ed i 166 ka (nicoletti et alii, 1981; metzeltin & vezzoli, 1983; barberi et alii, 1984) indicando che la chiusura del bacino permette ormai collegamenti diretti tra le aree vulcaniche e la costa. il tetto del terrazzo relativo si trova in affioramento tra le quote 30 e 45 m s.l.m. il successivo terrazzo affiorante alle quote 10-15 m s.l.m contiene strombus bubbonius ed è riferito quindi al tirreniano (palieri & sposato, 1988). i depositi costieri relativi sono correlati con quelli continentali tramite la presenza del deposito del tufo rosso a scorie nere vicano, datato a 155 ± 0.01 ka (sollevanti, 1983). nel loro insieme queste unità costituiscono il sintema casalone (fig. 6). le correlazioni stratigrafiche e le date geocronologiche hanno permesso, inoltre, di risolvere un’interessante questione che si è rivelata di grande importanza anche per la ricostruzione dell’evoluzione costiera dell’area romana. la questione concerne l’attribuzione cronologica di dama dama tiberina di st e f a n o & petronio che era correlata in passato allo stadio isotopico 7. denti appartenenti a questo cervide sono stati ritrovati all’interno del bacino di tuscania, in una sequenza continua di depositi con al tetto del travertino, la cui età radiometrica è risultata pari a 256 ka +41/31. questo ha portato all’attribuzione di dama dama tiberina allo stadio isotopico 9. 529 fig. 6 schema dei rapporti morfo-litostratigrafici dell’area del lazio settentrionale. 1) unità pre-pleistocene medio; 2) unità del pleistocene medio-superiore; 3) principali superfici erosive. (modificato da de rita et alii, 2002) morpholithostratigraphic scheme of the northern latium area. 1) pre-middle pleistocene units; 2) middle-upper pleistocene units; 3) main erosional surfaces. (modified from de rita et alii, 2002) fig. 5 schema dei terrazzi marini recenti nel lazio settentrionale. 1) superficie del terrazzo marino relativo allo stadio isotopico 5; 2) superficie del terrazzo marino relativo allo stadio isotopico 7; 3) superficie del terrazzo marino relativo alla stadio isotopico 9; 4) limiti di massima trasgressione marina realtivi ai tre terrazzi. (modificato da de rita et alii, 2002). schematic map showing recent marine terraces in northern latium. 1) isotopic stadi 5 marine terrace surface. 2) isotopic stadi 7 marine terrace surface. 3) isotopic stadi 9 marine terrace surface. 4) maximum marine transgression boundary. (modified from de rita et alii, 2002). evoluzione pleistocenica del margine ... area costiera romana l’area analizzata ricade ai limiti occidentali dei fogli geologici alla scala 1:50.000 albano e roma del progetto carg (fig. 1). come per il settore settentrionale, anche nell’area romana l’emersione inizia intorno a 850 ka (giordano et alii, 2003) mentre l’attività vulcanica, relativa ai distretti dei colli albani e dei sabatini, inizia intorno a 560 ka (karner & renne, 1998; giordano et alii, 2003). i sedimenti antecedenti, relativi al pleistocene inferiore sono stati organizzati all’interno di un supersintema, il supersintema monte mario, in quanto limitati da una superficie indotta da una fase tettonica (giordano et alii, 2002b). nell’area romana erano già stati riconosciuti diversi ordini di terrazzi marini (a m b r o s e t t i & bonadonna, 1967; bonadonna, 1967; conato & dai pra, 1980; conato et alii, 1980; carbone, 1980) correlati a stadi isotopici dal 15 al 5 (malatesta & zarlenga, 1985, 1986, 1988; milli, 1992, 1997; marra, 1993; marra & rosa, 1995; marra et alii, 1995; karner et alii, 2001a, b; bergamini et alii, 2000; giordano et alii, 2003). nell’area romana è presente un elemento di grande importanza nell’evoluzione del settore che è il corso del tevere. l’antico corso, paleotevere, occupava sicuramente una posizione diversa dall’attuale ed aveva la sua foce nell’area di ponte galeria (marra & rosa, 1995; milli, 1997). i depositi prevulcanici dell’area romana appartengono in gran parte all’attività di questo antico fiume. lo sviluppo del delta si colloca in un intervallo di tempo compreso tra gli stadi isotopici 22 e 16 in una vasta area compresa tra la dorsale di monte mario e la costa, interessata da sedimenti costieri che superano gli 80 m di spessore. la deviazione del corso del paleotevere in un percorso a se avviene tra 700 e 600 ka ed è causata dal sollevamento della dorsale di monte mario (fig. 7) (giordano et alii, 2002b, 2003). e’ probabile che l’ambiente fluvio-palustre relativo alla valle del paeotevere, in corrispondenza dell’area di sviluppo del vulcano tuscolano-artemisio, abbia fornito l’acqua necessaria ad innescare le eruzioni freatopliniane dei così detti “tufi pisolitici” (de rita et alii, 2002a). i depositi delle quattro eruzioni separati da paleosuoli che nel loro insieme comprendono i “tufi pisolitici” auctorum, si trovano in parte nel sintema di santa cecilia (stadio isotopico 15) e in quello di valle giulia (stadio isotopico 13) a testimonianza che un evento importante come l’oscillazione del livello del mare non abbia avuto alcuna ripercussione sullo stile eruttivo del vulcano in un momento di acme della sua attività. questa constatazione rafforza l’opportunità di mantenere nomenclature diverse per le suddivisioni a scala regionale e quelle inerenti all’attività vulcanica, per poter porre facilmente in relazione eventi vulcanici, vulcano-tettonici ed eventi a scala regionale di più ampio significato. gli ingenti volumi di materiale emessi nel corso delle eruzioni dei “tufi pisolitici” costringerà il tevere a modificare ulteriormente il suo percorso verso quello attuale. il sintema valle giulia, relativo allo stadio isotopico 13, oltre alle unità vulcaniche e ai depositi fluviali, contiene ingenti volumi di travertino a testimonianza di una tettonica attiva e di un importante sistema idrotermale (giordano et alii, 2003). nel successivo sintema torrino, relativo allo stadio isotopico 11 si ha la messa in posto dei massimi volumi dei prodotti vulcanici. poco dopo la messa in posto del tufo lionato e del tufo di villa senni datato a circa 350 ka (bernardi et alii, 1982; radicati di brozolo et alii, 1981; karner & re n n e, 1998) avviene il sollevamento dell’alto di castelporziano-pomezia lungo faglie ad andamento ne, probabile riattivazione di elementi strutturali attivi nel pliocene-pleistocene inferiore ai margini del bacino di ardea (facenna et alii, 1994). le unità del tufo lionato-villa senni nell’area costiera di anzio ed ardea poggiano su sabbie di spiaggia e su sedimenti marini a testimonianza del fatto che quello era il livello del mare al momento della loro deposizione. l’unità del villa senni è stata datata a circa 350 ka (bernardi et alii, 1982); in quest’epoca wealbroeck et alii (2002) hanno calcolato che il livello del mare era a -120 m r.l.m. il top dell’unità di villa senni è interessato da una superficie di abrasione, coperta da sabbie di spiaggia, duna e retroduna (“duna rossa antica” auctorum), relative allo stadio isotopico 9. nell’area di pomezia, castelporziano, questi sedimenti risultano sollevati fino ad una quota di 100 m s.l.m. probabilmente in conseguenza del sollevamento dell’alto avvenuto secondo direttrici strutturali ad orientamento ne (giordano et alii, 2003). i sedimenti del successivo sintema quartaccio si appoggiano alla struttura sollevata: si tratta di due unità, aurelia e vitinia, separate da una superficie di disconformità a basso rilievo (fig. 7). la quota di affioramento dell’unità aurelia è circa 30 m, mentre il tetto dell’unità vitinia è a circa 55-60 m s.l.m. il top dell’unità vitinia è datato a circa 285 ±1 (karner et alii, 2001b) per la presenza al tetto dei sedimenti di pomici riferite al tufo giallo di sacrofano proveniente dal vulcano di sacrofano nel distretto dei sabatini (de rita et alii, 1983). per queste relazioni il sintema quartaccio è correlato con lo stadio isotopico 9 e le due unità aurelia e vitinia sono considerati due suoi subsintemi. questa correlazione permette anche di confermare l’attribuzione del dama dama tiberina a questo stadio isotopico in accordo a quanto osservato lungo la costa settentrionale del lazio. a quote topografiche più basse, circa 3040 m, è stato riconosciuto un altro terrazzo i cui sedimenti costituiscono il sintema campo selva correlato allo stadio isotopico 7 e ancora più in basso, a circa 1530 m s.l.m un ultimo terrazzo i cui sedimenti costituiscono il sintema saccopastore correlato allo stadio isotopico 5. area costiera meridionale al confine con la campania (roccamonfina) per quanto riguarda l’area meridionale del lazio al confine con la campania (fig. 1) è possibile individuare un settore in continua subsidenza fin dalle fasi iniziali dell’evoluzione del vulcano di roccamonfina. infatti, in quest’area, pur avendo individuato sulla base delle analisi di facies e dei caratteri litologici dei sedimenti, le fasi sin e inter-eruttive di ogni eruzione del vulcano in un arco di tempo compreso tra i 600 ed i 250 ka, non è stato possibile stabilire alcuna relazione con la situazione costiera in mancanza di depositi correlabili (giordano et alii, 2002a; de rita et alii, 2003a). tuttavia, 530 d. de rita, m. fabbri & c. cimarelli sulla base delle date geocronologiche disponibili sono stati identificati 4 sintemi, correlati rispettivamente agli stadi isotopici 11, 9, 7 e 5 (fig. 8) (de rita et alii, 2003a). si riscontra una correlazione sorprendente di questi sintemi con quelli riconosciuti nei settori più a nord, almeno per l’intervallo di tempo relativo agli ultimi 400 ka. al di sotto, l’organizzazione delle unità in ubsu è molto più complessa: la successione delle unità eruttive relative alla crescita del vulcano di roccamonfina è stata organizzata all’interno di un unico sintema (sintema m. ofelio) che in realtà comprende più superfici relative alle oscillazioni del livello del mare, che non possono però essere correlate verso costa per la mancanza di affioramenti. tuttavia è possibile stabilirne l’inizio in coincidenza delle prime manifestazioni vulcaniche dell’area datate circa a 600 ka (ballini et alii, 1989). le unità vulcaniche poggiano su sedimenti sabbioso-argillosi quaternari e su conglomerati riferiti al pliocene superiore (conglomerati di minturno; giordano et alii, 1995), attualmente molto al di sotto del livello del mare, a testimonianza che, lungo questo tratto della costa meridionale del lazio, il vulcanismo è contemporaneo ad un processo di subsidenza. discussione dei dati e note conclusive il confronto dell’evoluzione dei settori analizzati permette alcune considerazioni di interesse generale e alcune conclusioni interessanti ai fini della ricostruzione 531 fig.7 schema delle principali caratteristiche strutturali, vulcaniche e geomorfologiche dell’area costiera romana. 1) terrazzo marino relativo allo stadio isotopico 5; 2) terrazzo marino relativo allo stadio isotopico 7; 3) terrazzo marino relativo allo stadio isotopico 9; 4) alto strutturale di pomezia-castel porziano; 5) corso del paleo-tevere;6) delta del paleo-tevere; 7) faglie principali; 8) caldere; 9) crateri. (modificato da giordano et alii, 2003) scheme of the main structural, volcanic, geomorphologic features of the roman coastal area. 1) isotopic stadi 5 marine terrace; 2) isotopic stadi 7 marine terrace; 3) isotopic stadi 9 marine terrace; 4) pomezia-castel porziano structural high; 5) paleo-tiber course; 6) paleo-tiber delta; 7) main faults; 8) caldera rim; 9) crater rim. (modified from giordano et alii, 2003) evoluzione pleistocenica del margine ... dell’evoluzione del margine costiero del lazio. l’attività vulcanica alcalino potassica è preceduta da un generale sollevamento costiero che porta all’emersione dell’area a circa 850 ka, contemporaneamente sia nel lazio settentrionale che in quello centrale. questo sollevamento ha interessato anche la piattaforma costiera ed è riconoscibile nei terrazzamenti presenti sulle isole pontine. mentre sul margine continentale non sono evidenti elementi strutturali significativi che hanno accompagnato tale sollevamento, nelle isole è ipotizzabile una tettonica estensionale che potrebbe risalire a questo intervallo di tempo. nel caso delle isole pontine, il lavoro di riconoscimento e correlazione delle superfici di discontinuità e dei terrazzi, ha posto una serie di problemi che vale la pena di riassumere: in caso di presenza di corpi intrusivi subsuperficiali di tipo criptodomi, superfici piane debolmente inclinate vengono prodotte dallo stesso processo di risalita del corpo intrusivo e non indicano necessariamente la presenza di un terrazzo marino, a meno del ritrovamento in situ dei sedimenti relativi. superfici piane, ad esempio si sono sviluppate durante la crescita del domo di syowa sinzan in giappone o del domo di lassen peak in california (williams & mc birney, 1979). la veloce crescita di questi domi, da pochi mesi a poche centinaia di anni, è in grado inoltre di giustificare, nel caso di domi cresciuti lungo la costa, la presenza di uno o più terrazzi basculati che non necessariamente indicano ordini di terrazzi successivi relazionabili alle oscillazioni del livello del mare (vedi il caso dell’isola di panarea). e’ quindi necessaria un’attenta valutazione della genesi delle varie superfici ed un loro confronto con quelle identificabili lungo la costa continentale. un altro dato interessante, ottenuto tramite la correlazione delle superfici di base dei sintemi con i momenti di basso stazionamento del livello del mare (fig. 8) è la presenza, lungo la costa del lazio, di tre ordini di terrazzi correlati agli stadi isotopici 9, 7 e 5, confrontabili tra loro per numero, età e quote. i tassi di sollevamento calcolati per l’area costiera del lazio settentrionale e per quella romana (fig. 9) sono dell’ordine di 0,2 mm annui, confrontabili tra loro ed in accordo con i tassi di sollevamento regionale calcolati per il tirreniano (bordoni & valensise, 1998, anzidei et alii, 2002). questo dato permette a sua volta di valutare gli effetti della tettonica regionale rispetto a quella locale. ad esempio localmente nell’area di castel porziano il tasso di sollevamento del sintema quartaccio, calcolato di circa 2,0 ± 0,2 mm/anno (giordano et alii, 2003), risulta di entità maggiore e consente di valutare tale entità come connessa all’azione di una tettonica locale. considerato poi l’intervallo di tempo relativo è possibile relazionare il sollevamento al climax dell’attività vulcanica, ricorso appunto in questo periodo (cavinato et alii, 1992, 1994). il riconoscimento di terrazzi analoghi sulla costa settentrionale e centrale del lazio pone un quesito interessante ai fini dell’organizzazione cartografica nazionale: i sintemi relativi infatti possono essere considerati a tutti gli effetti gli stessi (fig. 8) e come tali dovrebbero essere nominati allo stesso modo. questo significa che le nomenclature locali, prese dai toponimi maggiormente significativi per i fogli rilevati, non dovrebbero più essere valide e bisognerebbe trovare un nome significativo alla scala regionale, almeno del lazio. questo problema diviene ancora più evidente quando la correlazione dei sintemi si estende anche a settori come quello di roccamonfina (fig. 8) dove non sono presenti sedimenti costieri. il metodo di rilevamento ha però consentito di individuare nell’area vulcanica sintemi regionali che tramite le date geocronologiche si correlano perfettamente a quelli già individuati più nord. quindi anche in questo caso i sintemi dovrebbero avere una nomenclatura unificata. sarebbe interessante a questo punto avere dei confronti nell’area sabatina, non ancora oggetto di rilevamento alla scala 1:50.000, che potrebbe essere risolutiva per questo problema e dove tra l’altro sono presenti fattori locali di grande interesse come la messa in posto dei domi intrusivi di tolfa, dei ceriti e dei cimini che per età costituirebbero l’anello mancante tra l’area delle pontine e quella della costa sia in termini di estensione regionale che temporale. un altro problema riguarda la risoluzione di alcuni sintemi che sia nel lazio settentrionale che in quello centrale sono in realtà la somma di più sintemi (s. marcello a nord, ponte galeria al centro e m. ofelio a sud). questi sintemi in realtà contengono sicuramente più superfici relative a diversi momenti di basso ed alto stazionamento del livello del mare (milli, 1997; marra et alii, 1998) che non sono state introdotte per più motivi. a nord per la mancanza di sufficienti affioramenti, nel centro e a sud perché elementi come il delta del tevere e la crescita di un vulcano rendono difficile con la loro rapida sedimentazione l’attibuzione certa delle superfici riconosciute alle oscillazioni del livello del mare. quindi a rigore di logica in realtà i sedimenti relativi non costituiscono un unico sintema ma un’associazione di sintemi, che non può essere definita supersintema perché per questa definizione è necessaria una gerarchia delle superfici limiti maggiore. si vuole pertanto suggerire di introdurre un’ulteriore nomenclatura ad esempio associazione di sintemi, per apportare ulteriore suddivisioni nel futuro, qualora il dettaglio stratigrafico lo consentisse. un ultimo dato importante che vale la pena di sottolineare riguarda proprio la mancanza dei sedimenti nell’area costiera di roccamonfina. tale assenza permette di evidenziare il processo di subsidenza, per altro già noto, di questo settore (ippolito et alii, 1973; naso & tallini, 1993; catenacci & molinari, 1965; giordano et alii, 1995). si ringraziano vivamenti tutti i collaboratori al progetto carg, fogli geologici montalto di castro, tarquinia, roma , albano, borgo grappa e del progetto pilota roccamonfina. nota in una riunone avvenuta in sede apat nel gennaio 2005 è stata proposta una nomenclatura unificata dei supersintemi e dei sintemi riconosciuti come gli stessi lungo la costa del lazio. pertanto attualmente il supersintema aquatraversa ha sostituito i supersintemi monte riccio e monte mario; il supersintema aurelio-pontino ha sostituito i supersintemi marta, zannone e galeria; il sintema ponte galeria si chiama magliana; il sintema flaminia sostituisce il sintema santa cecilia; il sintema villa glori il valle giulia; il sintema barca di parma il quartaccio; il sintema fiume fiora archi di pontecchio e campo selva; ed infine il sintema fiume marta il casalone, zannone sud e saccopastore. il supersintema ponza ed il sintema pontino sono stati soppressi non avendo superfici di base identificate. 532 d. de rita, m. fabbri & c. cimarelli 533 fig. 9 confronto dei tassi di sollevamento calcolati per l’area costiera del lazio settentrionale e per l’area costiera romana. comparison of the uplift rates computed for the northern latium coastal area and for the roman coastal area. fig. 8 correlazione delle unità a limiti inconformi rapportata alla scala degli stadi isotopici (shackleton et alii, 1990; shackleton, 1995). lo schema evidenzia come l’organizzazione delle unità in ubsu, rapportata alle variazioni del livello del mare, permetta correlazioni significative a livello regionale, ponendo il problema della nomenclatura dei sintemi e supersintemi a questa scala. correlations between unconformity buonded stratigraphic units compared to the isotopic stadi scale (shackleton et alii, 1990; shackleton, 1995). the scheme evidences the ubsu methodology capability to allow stratigraphic correlations at regional scale. evoluzione pleistocenica del margine ... riferimenti bibliografici alberti a., bertini m., bono g.l., nappi g., salvati l. 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(2002) sea level and deep water temperature changes derived from benthic foraminifera isotopic records quat. sc. rev. 21, pp. 295-305. williams h., mc birney a.r. (1979) volcanology freeman cooper & co., san francisco. zitellini n., marani m., borsetti a.m. (1984) post-orogenic tectonic evolution of palmarola and ventotene basins (pontine archipelago) mem. soc. geol. it.; 27, pp. 121-131 536 ms. ricevuto l’11 maggio 2004 testo definitivo ricevuto il 22 giugno 2004 ms. received: may 11, 2004 final text received: june 22, 2004. d. de rita, m. fabbri & c. cimarelli imp.carobene_cevasco una deformazione gravitativa profonda di versante all’origine del piano di oneto, val graveglia (appennino ligure) luigi carobene1 & andrea cevasco1 1dip.te.ris – dipartimento per lo studio del territorio e delle sue risorse, università di genova corso europa 26, 16132 genova (italy). (e-mail: carobene@dipteris.unige.it cevasco@dipteris.unige.it) riassunto: l. carobene & a. cevasco, una deformazione gravitativa profonda di versante all’origine del piano di oneto, val graveglia (appennino ligure). (it issn 0394-3356, 2007). viene espressa una nuova ipotesi sulla genesi del piano di oneto, ubicato in alta val graveglia (appennino ligure), sulla base di un riesame degli aspetti deducibili dalle carte geologiche e topografiche e dalle evidenze di terreno. il piano di oneto costituisce una fra le più ampie superfici pianeggianti nell’area dell’appennino ligure e, per tale peculiarità, è oggetto, da oltre un ventennio, di notevole interesse da parte di geologi e geomorfologi. interpretato come una forma epigea di origine prevalentemente carsica esso è stato definito a più riprese la più grande “dolina” esistente in liguria orientale ed attualmente l’area di pertinenza viene considerata e perimetrata quale “monumento naturale” nel piano del parco naturale regionale dell’aveto. tuttavia, la revisione dei dati a disposizione e l’analisi degli elementi morfologici sia alla macroscala che alla mesoscala forniscono, assieme alla presenza di diversi indizi geologici e morfotettonici, nuovi elementi di discussione in parziale contrasto con le interpretazioni che attribuiscono al carsismo un ruolo di primaria importanza nella genesi del piano di oneto. le osservazioni effettuate sulla litologia e struttura del substrato, sulla morfologia e sulla tettonica recente dell’area ci portano a proporre un modello secondo il quale la depressione deriverebbe da un fenomeno gravitativo profondo favorito dalla presenza di un substrato “plastico”, dalle faglie e dal sollevamento plio-quaternario. è stata, inoltre, scartata l’ipotesi del glacialismo quale causa d’origine del piano di oneto. abstract: l. carobene & a. cevasco, a deep-seated gravitational slope deformation as the genesis of the piano di oneto, val graveglia (ligurian apennines). (it issn 0394-3356, 2007). a new hypothesis on the genesis of the piano di oneto, located in the upper val graveglia (ligurian apennines) (fig. 1), on the basis of field studies and a re-examination of the features distinguishable in geological and topographical maps and aerial photographs. the piano di oneto is one of the largest flat areas of the ligurian apennines; interpreted as an epigeal form of prevalently carsic origin, it has been defined more than once as the largest existing “dolina” in eastern liguria (fig. 7). a review of the available data, an analysis of the morphological features at both the macroand mesoscale and various geological and morphotectonic characteristics provide a new basis for discussion. from a geological point of view (fig. 2) the area is characterised by formations associable with the val di vara supergroup (internal ligurids of various authors), divided into two main units, the underlying mt. porcile unit and the overlying mt. zatta unit (gottero unit of various authors). the former contains notable ophiolitic sequences (basalts, serpentinites), a volcano-sedimentary complex (ophiolitic breccias) and a sedimentary cover (mt. alpe jaspers, calpionelle limestones, palombini clays). a little to the east of the val graveglia – val di vara watershed, under the mt. porcile unit, lies the colli-tavarone formation (upper cretaceous – palaeocene), which consists of layered claystones interspersed with thin layers of siltites and calcarenites. various authors have studied the structure of this area, which is exceptionally complex. its complexity is evident in the cross section reported in fig. 3, the trace of which is visible in fig. 2. all the structural reconstructions made of the area underline the fact that there is no carbonatic mass under the piano di oneto. since the pliocene, the complicated structural situation described above has been subjected to extensional tectonics that have given it its peculiar morphostructural conditions and been the main underlying cause of landslides in this zone as in other parts of liguria. an analysis of the orientation of the hydrographic network and the watershed lines indicate their close dependence on the main neotectonic lines, which are oriented ene – wsw (56° 66°), nnw – sse (150°), n – s and e – w. it is possible to say that the majority of the geomorphological alignments correspond to fracture systems or plio-quaternary faults but not to the more ancient faults visible in fig. 2. in the area under study (fig. 6) there are morphological features (reverse slopes, bulges and landslides) that are specific signs of gravitational slope deformations. the studies carried out indicate that the genesis of the piano di oneto should be looked for in a “deep-seated gravitational slope deformation” caused by the high energy of the relief associated with the uplift of the zone and the high erosive capacity of the watercourses that have caused the deepening of the hydrographic network. given the above scenario, the depression under study could be interpreted as the filling up of a trench running parallel to the ridge (nw – se) with silty-clayey material washed down from the surrounding slopes (figs. 6 and 9). we believe that only its extension towards the wsw, where there seem to be calpionelle limestones, can be imputed to carsic and erosive phenomena. parole chiave: dgpv, morfotettonica, dolina, val graveglia, appennino ligure. keywords: dgsd, morphotectonics, dolina, val graveglia, ligurian apennines, italy. il quaternario italian journal of quaternary sciences 20(1), 2007 45-56 1. sintesi degli studi sull’area vengono di seguito forniti i principali aspetti descrittivi, morfologici, litologici e tettonici atti alla comprensione dell’area. viene inoltre esposta una sintesi sull’origine carsica dell’area. 1.1. inquadramento morfologico e litologico il piano di oneto è ubicato nell’alta val graveglia (appennino ligure), in prossimità dello spartiacque che la delimita dalla val di vara, ad una quota compresa fra 830 e 835 m. l’orografia della zona oggetto di studio, che com46 l. carobene & a. cevasco prende la porzione nord-orientale del bacino del t. graveglia ed il limite occidentale del bacino del t. vara (fig. 1), è caratterizzata da un tratto della dorsale compresa fra m. zatta (1404 m) e m. porcile (1249,5 m), orientata in direzione nno – sse (150°) e contraddistinta, procedendo verso sse, dai rilievi di m. prato pinello fig. 1 topografia semplificata del settore nord-orientale della val graveglia con ubicazione del piano di oneto. legenda: 1) linea spartiacque principale; 2) linee spartiacque secondari; 3) corsi d’acqua principali; 4) corsi d’acqua secondari; 5) isoipse (equidistanza 100 m); 6) ripiani entro depressioni; 7) culminazioni principali lungo gli spartiacque. simplified topography of the north-eastern sector of the val graveglia with the location of the piano di oneto. legend: 1) main watershed line; 2) secondary watershed lines; 3) main water courses; 4) secondary water courses; 5) contours (equidistance 100 m); 6) plains inside depressions; 7) main watershed summits. (1391 m), m. coppello (1061,6 m), m. chiappozzo (1126,5 m), quota 957,9 m, quota 977 m, m. biscia (991,1 m), quota 1000,7 m e m. porcile (1249,5 m) (non tutti visibili nelle figg. 1 e 5). ad ovest dello spartiacque (val graveglia) il corso d’acqua principale è rappresentato dal t. reppia, che scorre in direzione n s fra le pendici meridionali del m. zatta (posto a nord, fuori carta) e la località ponte lagoscuro dove, confluendo con il rivo orti, dà origine al t. graveglia. i tratti del corso d’acqua in direzione n – s (fig. 5) presentano netti cambi di direzione causati da un sistema di dislocazioni circa ene – oso (56° ÷ 66°). ad esse corrispondono diversi corsi d’acqua sul versante sinistro del t. reppia (rio casoni, rio prato, rivo orti). anche il crinale risente del citato sistema di dislocazioni, che provoca sia discontinuità planimetriche che altimetriche (fig. 5), le maggiori delle quali si trovano in prossimità del passo del biscia (q. 890,6 m). alla maggiore dislocazione del crinale sembra aver contribuito anche il lineamento, posto circa e – o (93°), evidenziato dall’allineamento di tratti rettilinei dei corsi d’acqua di rio soprano, rio prato e canale del biscia (figg. 1 e 5). nella parte più elevata del bacino del t. reppia i versanti si presentano assai scoscesi, i corsi d’acqua tendenzialmente rettilinei, fortemente incisi e ripidi; a valle dell’abitato di reppia, l’asta principale risulta ancora profondamente incisa fra versanti assai acclivi. ad e dello spartiacque (val di vara) il corso d’acqua principale è rappresentato dal t. vara, che per un ampio tratto scorre in direzione nno – sse fino alla località pietragrossa, dove curva repentinamente di 90° e prosegue il suo percorso in direzione ono – ene (gomito di origine tettonica legato ai sistemi di faglie sopra citati). alcuni affluenti sulla destra orografica del vara, fra i quali il rio coppello, il canale del biscia ed il rio freddo, drenano i ripidi versanti sottostanti lo spartiacque principale, esposti a ne, compresi fra m. coppello e m. porcile (fig. 1). in generale si osserva una stretta dipendenza fra lo sviluppo del reticolo idrografico e le caratteristiche di permeabilità dei litotipi presenti: in particolare esso appare ben sviluppato in corrispondenza delle formazioni a dominante pelitica (argille a palombini, formazione di colli/tavarone), tendenzialmente impermeabili; ben controllato da linee di frattura e/o di faglia nel caso di litotipi ofiolitici, ed assai poco evidente in corrispondenza di litotipi calcarei (calcari a calpionelle), dotati di permeabilità per fratturazione e carsismo. i versanti in sinistra idrografica del t. reppia presentano in generale profili assai irregolari, testimoni di un’evoluzione tormentata dovuta, da un lato, all’estrema eterogeneità litologica ed al complesso assetto geologico-strutturale, dall’altro agli effetti della tettonica recente (faglie e sollevamento), che ha condizionato in maniera evidente l’impostazione del reticolo idrografico ed ha determinato un’accentuata energia del rilievo. tali fattori sembrano aver avuto un ruolo fondamentale nella predisposizione al verificarsi di un elevato numero di fenomeni franosi, sia attivi sia quiescenti, nonché di deformazioni gravitative profonde di versante (dramis et al., 1985; sorriso-valvo, 1998; 1995) già segnalate in altre parti della liguria (marini, 1994; marini, 2002; regione liguria, 2002a; 2002b; federici et al., 2004). sotto il profilo geologico (fig. 2) l’area è caratterizzata dalla presenza di termini riconducibili al supergruppo della val di vara (liguridi interne auctt.), suddivisi in due unità principali (abbate et al., 1980-92, galbiati & principi, 1990) fra loro sovrapposte: l’unità di m. porcile e la sovrastante unità di m. zatta (unità gottero auctt.). in particolare, per quanto riguarda la 47una deformazione gravitativa profonda ... prima, sono rappresentate le note sequenze ofiolitiche (basalti, serpentiniti), il complesso vulcano-sedimentario (brecce ofiolitiche) e le coperture sedimentarie (diaspri di m. alpe, calcari a calpionelle, argille a palombini) che riflettono l’evoluzione del dominio ligure interno fra il giurassico medio-superiore ed il cretaceo inferiore. in prossimità del limite nord-orientale del bacino del t. graveglia si sovrappone alla precedente l’unità di m. zatta, qui rappresentata dall’insieme delle formazioni degli scisti della val lavagna e delle arenarie di m. gottero (cretaceo sup. – paleocene), costituite rispettivamente da torbiditi pelitico-arenacee e da potenti sequenze di torbiditi arenacee. poco ad e dello spartiacque val graveglia val di vara, al disotto dell’unità di m. porcile, compare la formazione di colli-tavarone (cretaceo sup. – paleocene), ascrivibile all’unità di colli-tavarone (meccheri et al., 1986, marroni & meccheri, 1993), costituita da argilliti fogliettate con sottili intercalazioni di siltiti e calcareniti (questa unità era citata come “sedimentario esterno” in galbiati, 1970). 1.2. le precedenti indagini e ipotesi sulla genesi dell’area il piano di oneto, per le sue dimensioni notevoli, è ben individuabile nella cartografia geologica disponibile per tale zona alla scala 1:25.000 (decandia & elter, 1972; abbate et al., 1980-92; regione liguria, 2006). la peculiare morfologia della zona, unitamente alla scarsità di aree pianeggianti di una certa estensione a quota elevata in liguria, aveva attirato già dal 1939 l’attenzione di rovereto che ne effettuò una prima descrizione. solo nel 1968 furono studiati i dettagli morfologici superficiali (cozzani, 1968) e, contemporaneamente, ci si pose il problema dell’identificazione del percorso delle acque infiltrate nell’inghiottitoio principale (maifredi & giammarino, 1968). secondo questi ultimi, che effettuarono prove mediante traccianti, le acque non tornerebbero alla luce presso la sorgente di cà freghè (situata in corrispondenza dell’adiacente rivo orti, fig. 1) come ritenuto localmente bensì, con buona probabilità, in corrispondenza di risorgenti (peraltro, allo stato attuale, non ancora identificate) in val di vara. poco più tardi, alcune indagini geofisiche permisero di ottenere una prima indicazione sull’andamento del substrato in corrispondenza del piano (maifredi & pastorino, 1972). in particolare le indagini, che consistettero in sondaggi elettrici verticali e nella costruzione di una carta delle isoresistive, evidenziarono una morfologia sotterranea assai peculiare, caratterizzata dalla presenza di un ripido imbuto il cui fondo, a profondità superiore a 70 m, non corrisponde all’inghiottitoio attivo, situato nel settore nord-orientale della depressione. secondo gli autori, in corrispondenza dell’inghiottitoio (fig. 4) che si apre nei depositi di riempimento della depressione, il substrato calcareo si trova ad una profondità di 12 m. una recente campagna di indagini geofisiche (brandolini et al., 2005) sembra confermare i risultati delle indagini di cui sopra, pur riducendo a pochi metri lo spessore del sedimento detritico in corrispondenza dell’inghiottitoio attivo (fig. 4). nel modello di brandolini et al., 2005 il fondo della depressione non è “a imbuto” come in maifredi & pastorino (1972), ma allungato irregolarmente e ubicato in una diversa posizione; la sua profondità non sembra superare i 40 – 50 m. 48 fig. 2 schema geologico del settore nord-orientale della val graveglia (da galbiati, 1970; ridisegnato). legenda: 1) arenarie di m. gottero, formazione della val lavagna; 2) argille a palombini; 3) calcari a calpionelle; 4) diaspri; 5) basalti e brecce associate; 6) serpentiniti, gabbri e oficalciti; 7) formazione di colli-tavarone; 8) ubicazione delle depressioni studiate; 9) contatti tettonici di maggiore evidenza; a) faglia di trambacco; b) faglia di costa ricasola; 10) sovrascorrimenti; 11) traccia di sezione geologica. geological scheme of the north-eastern sector of the val graveglia (based on galbiati, 1970; redrawn). legend: 1) mt. gottero sandstones, val lavagna formation; 2) palombini clays; 3) calpionelle limestones; 4) jaspers; 5) basalts and associated breccias; 6) serpentinites, gabbros and ophicalcites; 7) colli-tavarone formation; 8) position of the plains studied; 9) most visible tectonic contacts; a) trambacco fault; b) costa ricasola fault; 10) thrusts; 11) trace of geological section. l. carobene & a. cevasco 49 2. assetto tettonico-strutturale antico e recente 2.1. gli aspetti strutturali sotto il profilo strutturale l’area, caratterizzata da una notevole complessità, è stata indagata in varie fasi da diversi autori (decandia & elter ,1969 e 1972; nosengo, 1970; galbiati 1970 e 1977; più recentemente da a bbate et al., 1980; m arroni, 1990; m arroni & meccheri, 1993). nonostante ciò, esistono a tutt’oggi divergenze fra le ricostruzioni dei rapporti stratigrafici e tettonici tra le diverse unità presenti. sembra, tuttavia, accertata l’esistenza di una megastruttura coricata (parzialmente visibile in fig. 3) che si sviluppa per tutta la val graveglia con un’estensione di circa 5 km e coinvolge i termini dell’unità di m. porcile compresi fra le ofioliti e le argille a palombini. la cerniera di tale struttura, affiorante sulle pendici orientali di m. chiappozzo, è caratterizzata da un asse orientato circa 140°/15° no e da un piano assiale orientato circa 138°/12° so (marroni, 1990). il fianco diritto è osservabile nei dintorni di reppia e sulle pendici occidentali di m. chiappozzo, mentre il fianco rovesciato affiora in corrispondenza di costa ricasola (crinale a e del colle ricasola, fig. 1), lungo la valle del torrente reppia e ad e di m. chiappozzo. tale struttura, caratterizzata da numerose “drag folds” di notevoli dimensioni e deformata in antiformi e sinformi, è delimitata, verso e, da un piano di sovrascorrimento (figg. 2 e 3) che separa l’unità di m. porcile dall’unità di colli-tavarone mentre a ovest scompare sotto l’unità di m. zatta (marroni, 1990). secondo galbiati & principi (1994) l’area sulla quale è impostato il piano di oneto corrisponde ad una depressione strutturale delimitata, sia sul fianco settentrionale che su quello meridionale, da faglie dirette orientate circa oso ene (faglia di trambacco e faglia di costa ricasola, fig. 2). la notevole complessità sotto il profilo geologicostrutturale è evidenziata dalla sezione riportata in fig. 3 (galbiati, 1970), la cui traccia è visibile in fig. 2. in ogni caso tutte le ricostruzioni strutturali effettuate nell’area mettono in evidenza che in corrispondenza del piano di oneto non esiste un massiccio carbonatico. 2.2. la neotettonica al complicato assetto strutturale cui si è fatto sinteticamente cenno si sono sovrapposti, a partire dal pliocene, gli effetti della tettonica recente che ha determinato condizioni morfostrutturali peculiari divenendo anche in questa zona, come già in altre parti della liguria, la causa predisponente principale della franosità. già da tempo diversi studi (fanucci & nosengo, 1979; nosengo, 1979) hanno evidenziato l’esistenza di motivi strutturali distensivi che interessano il versante marittimo dell’appennino sotto forma di linee tettoniche subverticali con andamento sia longitudinale sia trasversale alla catena, che viene suddivisa in “blocchi” ad evoluzione indipendente, legati al sollevamento plioquaternario dell’area. al fine di definire il quadro morfotettonico alla scala locale, è stato realizzato uno studio dei principali elementi morfologici (forma del reticolo idrografico, gomiti lungo i corsi d’acqua, andamento rettilineo degli spartiacque principali, salti altimetrici lungo i crinali, selle principali, lineamenti), i risultati del quale sono fi g . 3 s e zi o n e g e o lo g ic a f ra i l t . r e p p ia e i l t . v a ra ( la t ra c c ia è i n d ic a ta i n f ig .2 ) (d a g a lb ia ti , 1 9 7 0 ; ri d is e g n a ta ). l e g e n d a : 1 ) a rg ill e a p a lo m b in i; 2 ) c a lc a ri a c a lp io n e lle ; 3 ) d ia sp ri ; 4 a ) b a sa lt i; 4 b ) b re c c e o fio lit ic h e ; 5 a ) g a b b ri e o fic a lc it i; 5 b ) s e rp e n ti n it i e o fic a lc it i; 6 ) f o rm a zi o n e d i c o lli -t a va ro n e ; 7 ) f a g lie e c o n ta tt i t e tt o n ic i. g e o lo g ic al s e c ti o n b e tw e e n t h e r e p p ia a n d v ar a t o rr e n ts ( th e t ra c e is in d ic at e d in f ig . 2 ) (f ro m g al b ia ti , 1 9 7 0 ; re d ra w n ). l e g e n d : 1 ) p al o m b in i c la ys ; 2 ) c al p io n e lle l im e st o n e s; 3 ) ja sp e rs ; 4 a) b as al ts ; 4 b ) o p h io lit ic b re c c ia s; 5 a) g ab b ro s an d o p h ic al c it e s; 5 b ) s e rp e n ti n it e s an d o p h ic al c it e s; 6 ) c o lli -t av ar o n e f o rm at io n ; 7 ) fa u lt s an d t e c to n ic c o n ta c ts . una deformazione gravitativa profonda ... 50 riportati in fig. 5. l’analisi dell’orientazione del reticolo idrografico e delle linee spartiacque indica, in particolare, una stretta dipendenza fra essi e le principali direttrici tettoniche. in particolare i motivi tettonici principali sono rappresentati da direttrici ene – oso (56° ÷ 66°), nno – sse (150°), n – s ed e – o. si ritiene che gran parte dei lineamenti individuati su base geomorfologica corrispondano a sistemi di fratture o di faglie plio-quaternarie non corrispondenti alle faglie antiche visibili in fig. 2. i rapporti fra i principali sistemi sono assai complessi avendo essi, con ogni probabilità, giocato in tempi differenti. nell’area in esame esse individuano almeno due “blocchi” principali indipendenti; il limite occidentale dei “blocchi” coincide con il sistema di lineamenti che hanno condizionato il corso del t. reppia, mentre quello orientale è determinato dal sistema di lineamenti nno-sse da ubicare a e dello spartiacque (val di vara). in particolare un primo blocco (a, fig. 5), comprendente parte del tratto di crinale fra m. chiappozzo e m. coppello, è limitato verso n da una faglia diretta ene-oso (n63°) (evidente cambio di direzione del t. reppia a monte dell’abitato omonimo, cambio di direzione e salto altimetrico del crinale m. coppello – m. chiappozzo, brusco cambio di direzione del rio coppello, affluente del vara) e da una linea tettonica in direzione e – o (cambio di direzione di rivi minori); verso s il blocco è limitato dall’interazione di faglie dirette ene – oso (n68°) ed e – o (doppio gomito del corso del t. reppia, tratto rettilineo del rio prato, brusco salto altimetrico del crinale del m. chiappozzo, tratto rettilineo del canale del biscia). un secondo blocco (b, fig. 5), centrale, è delimitato verso n dal sistema sopra citato e verso s dalla linea tettonica orientata ene – oso (n56°), di importanza regionale, lungo la quale è impostato il corso del t. graveglia e quello del rivo orti. la porzione meridionafig. 4 carta geologica dell’area del piano di oneto con isopache (base geologica da abbate et al., 1980-92; ridisegnata e integrata da dati di terreno; isopache dei sedimenti nell’area indagata da brandolini et al., 2005, ridisegnato). legenda: 1) coperture detritiche quaternarie; 2) argille a palombini; 3) calcari a calpionelle; 4) diaspri; 5) ofioliti e brecce associate; 6) formazione di colli-tavarone; 7) faglie e contatti tettonici; 8) strati a polarità incerta; 9) strati diritti; 10) assi di pieghe; 11) isoipse del piano di oneto (equidistanza 2 m); 12) inghiottitoio; 13) isopache dei sedimenti. geological map of the area of the piano di oneto with isopachs (based on abbate et al., 1980-92; redrawn and integrated with new field data; sediment isopachs of the area studied by brandolini et al., 2005, redrawn). legend: 1) quaternary detrital cover; 2) palombini clays; 3) calpionelle clays; 4) jaspers; 5) ophiolites and associated breccias; 6) colli-tavarone formation; 7) faults and tectonic contacts; 8) beds with uncertain polarity; 9) beds with normal polarity; 10) fold axes; 11) contours of the piano di oneto (equidistance 2 m); 12) sinkhole; 13) sediment isopachs. l. carobene & a. cevasco 51 fig. 5 carta della tettonica post-compressiva legata al sollevamento isostatico plio-quaternario. legenda: 1) linee tettoniche; 2) corsi d’acqua principali; 3) linee di rottura del versante dovute alla deformazione gravitativa profonda; 4) discontinuità altimetriche importanti di crinale; 5) tratti ad andamento rettilineo dello spartiacque; il tratto a n si riferisce all’allineamento m. chiappozzo – m. prato pinello (fuori carta); 6) gomiti fluviali principali; 7) selle principali; 8) ripiani; 9) area interessata dalla deformazione gravitativa profonda. map of the post-compressive tectonics associated with the plio-quaternary isostatic rise. legend: 1) tectonic lines; 2) main water courses; 3) rupture lines due to deep-seated gravitational slope deformation (dgsd); 4) main altimetric ridge discontinuities; 5) rectilinear watershed trend tracts; the northern tract refers to the mt. chiappozzo – mt. prato pinello alignment (off map); 6) main river bends; 7) main saddles; 8) plains; 9) area affected by the dgsd. le del blocco, che comprende la dorsale di m. ricasola, è interessata da una serie di “superfici di rottura”, che testimoniano un’espansione del versante verso oso, riconoscibili da evidenze morfologiche (corsi d’acqua, selle, contropendenze e ripiani). gli effetti sopra esposti si sovrappongono a quelli di una faglia antica ad elevata inclinazione (direzione n71°), denominata “faglia di costa ricasola”, responsabile del ribassamento delle formazioni dei calcari a calpionelle e delle argille a palombini rispetto ai basalti ed alle brecce di m. capra. la porzione settentrionale dello stesso blocco pare inoltre aver subito un maggiore spostamento verso una deformazione gravitativa profonda ... oso. in fig. 5 si può ancora osservare che anche lo spartiacque val graveglia val di vara, nel tratto compreso fra m. chiappozzo e quota 977,0 m, appare coinvolto in tale spostamento. le evidenze morfologiche, in questo caso, sono costituite da notevoli discontinuità altimetriche del crinale e dalla presenza di due selle (rispettivamente sella a s del colle del chiappozzo e sella in corrispondenza del passo del biscia) che isolano il rilievo di quota 957,9 m. 3. caratteri morfologici del versante il versante lungo il quale è ubicata la depressione del piano di oneto (fig. 6) si sviluppa fra lo spartiacque val graveglia – val di vara (rilievo a quota 957,9 m) ed il torrente reppia, che scorre in questo tratto ad una quota di circa 350 400 m. esso presenta pertanto un dislivello pari a circa 550 m ed un’inclinazione media pari a circa 12° considerando la distanza fra la linea spartiacque ed il fondovalle pari a circa 2,6 km. il profilo del versante risulta irregolare (paragr. 1.1.), anche per la presenza di fenomeni franosi sia attivi che quiescenti (provincia di genova, 2003; fig. 6); procedendo da monte gli elementi morfologici salienti sono i seguenti: a) rilievo a quota 957,9 m (argille a palombini): è delimitato verso n e verso s da due selle. esso si trova sull’allineamento m. biscia – m. porcile (fig. 5), costituito da cinque culminazioni principali del crinale: 957,9 m – 977,0 m – 991,1 m – 1000,7 m 1249,5 m; esso risulta “disassato” rispetto all’allineamento m. chiappozzo (1126,5 m) – m. prato pinello (1390,6 m) (come si è detto al paragrafo 1.1.); b) depressione del piano di oneto (substrato costituito da argille a palombini, calcari a calpionelle, basalti e brecce ofiolitiche): la depressione presenta un perimetro irregolare, lungo 1140 m, coincidente con la base dei versanti circostanti, una superficie leggermente inferiore a 0,1 kmq ed allungamento in direzione ne – so (fig. 5 e fig. 7). il punto maggiormente depresso è situato a quota 829,5 m in prossimità del margine sud-occidentale, in corrispondenza di un “inghiottitoio” attivo. la quota massima del ripiano, pari a 835, 3 m, si trova a ne. i versanti circostanti presentano inclinazioni assai varie ed in particolare essi risalgono ripidamente (38°) sia verso s, fino alla dorsale di m. ricasola, sia verso ne (23°), fino al rilievo di quota 957,9 m; appare decisamente più blanda (13°) l’inclinazione media del versante a w della depressione. il piano di oneto raccoglie le acque di un rivo a carattere torrentizio che lo attraversa in direzione circa e – o (fig. 1). poco a n della depressione, a quote comprese fra 840 ed 850 m, è presente una seconda superficie subpianeggiante con caratteri morfologici assai simili, anche se di dimensioni inferiori, rispetto alla precedente. in questo caso il perimetro è di circa 800 m e la superficie pari a circa 0,033 kmq; c) rilievo a quota 870,0 m (calcari a calpionelle): è interessato, lungo il versante occidentale, da una grande frana i cui depositi si rinvengono fra 810 m e 475 m (decandia & elter, 1972; abbate et al., 1980; provincia di genova, 2003); i cigli di distacco si trovano a quota di circa 825 m (provincia di genova, 2003; federici et al., 2004; fig. 6); d) ampia superficie subpianeggiante a quota 600 m ca. (substrato costituito da serpentiniti, gabbri, oficalciti) sulla quale è stato costruito l’abitato di arzeno: è caratterizzata dalla presenza di estese coperture detritiche di origine franosa, frutto di riattivazioni in diverse fasi di un originario scorrimento rotazionale evoluto successivamente in colata (secondo federici et al., 2004); e) scarpata fra la superficie di cui al punto precedente ed il t. reppia (argille a palombini, calcari a calpionelle). si tratta di un versante ad elevata acclività, sede di fenomeni franosi causati da erosione spondale da parte del t. reppia. 4. discussione alla luce del quadro di riferimento delineato nei paragrafi precedenti si espone una serie di elementi che contrastano con le interpretazioni che attribuiscono al carsismo un ruolo determinante nella genesi del piano di oneto. già maifredi & pastorino, (1974) avevano espresso la perplessità che l’area costituisse una “situazione ideale per la formazione di una dolina tipica”. in particolare gli aspetti che, in questo caso, riteniamo differenti rispetto a quelli che permettono la formazione delle classiche doline riguardano: il contesto topografico-morfologico: le doline si formano, in genere, su massicci calcarei subpianeggianti (altopiani carsici) in contesti che permettano la permanenza e la successiva, lenta, infiltrazione delle acque superficiali (nel caso in esame il contesto è, invece, di versante). le dimensioni e la profondità: le notevoli dimensioni della depressione, in questo caso, richiederebbero l’esistenza, in profondità, di un corpo carbonatico di rilevante spessore interessato da carsismo ipogeo. la natura del substrato: come visto precedentemente, il ripiano si estende in prossimità del contatto fra litotipi ofiolitici (basalti) e coperture sedimentarie (brecce ofiolitiche, calcari a calpionelle, argille a palombini). l’ipotesi più verosimile, per quanto riguarda l’estensione dei litotipi al disotto della copertura detritica (figg. 8 e 9), prevede la presenza, lungo il margine meridionale della depressione, dei basalti e delle brecce ofiolitiche, lungo il margine occidentale dei calcari a calpionelle e delle argille a palombini, mentre lungo i margini settentrionale ed orientale delle argille a palombini. la posizione “anomala” dell’inghiottitoio superficiale rispetto sia al punto di massimo spessore del riempimento sia rispetto al centro del ripiano (fig. 4): la peculiare morfologia sotterranea del substrato indicherebbe il maggiore approfondimento (fino a 50 70 m) in prossimità del margine ne del piano (anziché in corrispondenza del centro della depressione); inoltre, in corrispondenza dell’inghiottitoio esistente, situato al margine so, lo spessore dei detriti sarebbe al massimo dell’ordine di 10-12 m (maifredi & pastorino, 1972) e, secondo brandolini et al. (2005) di soli pochi metri. la tipologia dei depositi di riempimento: la depressione è interamente riempita da materiale colluviale con forte componente argillosa, che non può favorire ma solo ostacolare lo sviluppo di carsismo; esso proviene dal dilavamento dei versanti circostanti, costituti da litotipi argillosi ed ofiolitici (argille a palombini, basalti, 52 l. carobene & a. cevasco brecce ofiolitiche). oltre alle considerazioni sopra esposte, a sfavore dell’origine carsica, vi è la presenza del ripiano esteso poco a n, assai simile sotto il profilo morfologico al piano di oneto, il substrato del quale risulta inequivocabilmente essere costituito solamente dalle argille a palombini. infine, prendendo in esame altre ipotesi, non sembra possibile che la genesi della depressione sia in qualche modo riconducibile al modellamento glaciale a causa della quota, ridotta, della zona (830 m). essa infatti, risulta inferiore sia al limite delle nevi persistenti nel würmiano, situato nell’appennino ligure orientale attorno a 1600 m, sia al limite inferiore raggiunto dalle lingue glaciali, pari a 1050 m ca. (rovereto, 1939). le osservazioni effettuate indicano che la genesi 53 fig. 6 carta della tettonica post-compressiva legata al sollevamento isostatico plio-quaternario e delle forme connesse alla dgpv (particolare della fig. 5). legenda: 1) linee tettoniche; 2) spartiacque principale; 3) spartiacque secondari; 4) linee di rottura del versante dovute alla deformazione gravitativa profonda; 5) fronti dei principali accumuli franosi; 6) rigonfiamenti del versante con contropendenza a monte; 7) discontinuità altimetriche di crinale; 8) andamento rettilineo di creste; 9) gomiti fluviali principali; 10) selle principali; 11) ripiani; 12) faccette triangolari; 13) inghiottitoio; 14) traccia di sezione geologica. map of the post-compressive tectonics associated with the plio-quaternary isostatic rise and the forms associated with the dgsd (detail of fig. 5). legend: 1) tectonic lines; 2) main watershed; 3) secondary watershed; 4) slope rupture lines due to dgsd; 5) main landslide accumulation fronts; 6) slope bulges with reverse slops; 7) altimetric ridge discontinuities; 8) rectilinear ridge trend; 9) main river sharps; 10) main saddles; 11)plains; 12) triangular facettes; 13) sinkhole; 14) trace of geological section. una deformazione gravitativa profonda ... della forma in oggetto debba essere ricercata in una deformazione gravitativa profonda di versante causata dalla vivace energia del rilievo connessa al sollevamento della zona, nonché dall’elevata capacità erosiva dei corsi d’acqua che ha determinato un forte approfondimento del reticolo idrografico. un ruolo favorevole allo sviluppo del movimento gravitativo potrebbero aver avuto le due faglie (in corrispondenza del rio prato e del rivo orti, fig. 5) agendo, in particolare, come “linee di svincolo” del blocco interessato. nell’area in esame (figg. 5 e 6) non mancano le evidenze morfologiche (contropendenze dei versanti, rigonfiamenti e movimenti franosi) che sono peculiari indizi delle deformazioni gravitative profonde di versante (sorrisovalvo, 1979; 1988). in particolare, altri evidenti indizi morfologici di dgpv, che implicano volumi rocciosi di varia entità, sono presenti lungo i versanti che degradano dallo spartiacque sia verso la val graveglia (a ese di m. chiappozzo e a n di case soprane, all’interno del blocco a, e più a s in prossimità di statale), sia verso la val di vara (a ene di m. coppello, parzialmente visibile in fig. 5). in riferimento al versante in oggetto, delimitato all’interno del “blocco b” (figg. 5 e 6), il complicato assetto strutturale determina condizioni assai varie che in molti casi danno origine alla sovrapposizione fra ammassi rocciosi a differente comportamento meccanico. l’aspetto principale, tuttavia, è legato al fatto che il “blocco” è caratterizzato, per la quasi totalità della sua estensione, dalla presenza di un substrato “plastico” costituito dalle argille a palombini (fig. 3) al quale, anche se con modalità diverse, sono sovrapposti ammassi rocciosi di varia natura a comportamento “rigido” (serpentiniti, basalti, brecce ofiolitiche, diaspri, calcari a calpionelle). in relazione alle proprietà meccaniche delle argille a palombini, prove geotecniche eseguite sulla stessa formazione in casi di studio sull’appennino modenese e reggiano (cancelli et al., 1987) hanno messo in evidenza un comportamento geotecnico tipico delle terre argillose di plasticità medio-alta e tendenza al rigonfiamento mentre, per quanto riguarda l’angolo di attrito, sono caratterizzate da valori di picco relativamente elevati (38° – 39°) e valori residui piuttosto bassi (10°-12°). per tali formazioni è noto, tuttavia, che elevate pressioni interstiziali possono giustificare l’innesco di frane e, nel lungo termine, la stabilità di versanti già dissestati dipende dai valori dell’angolo di resistenza residuo che, come sopra illustrato, è assai ridotto per tali litotipi. il modello di deformazione che si può ipotizzare costituisce una base di lavoro che tende inevitabilmente a schematizzare le condizioni reali, ben più complesse. esso presuppone l’esistenza di deformazioni plastiche in corrispondenza delle argille a palombini, private del contrasto laterale in conseguenza dell’approfondimento del solco di fondovalle, lungo orizzonti profondi di maggiore debolezza. entro tali fasce andrebbero a radicarsi numerose discontinuità di neoformazione (denominate in precedenza “superfici di rottura”, fig. 6) che avrebbero contribuito in varia maniera allo smembramento ed all’espansione del versante verso oso. queste ultime, particolarmente evidenti nella zona meridionale del blocco, in corrispondenza degli ammassi a comportamento rigido (ofioliti e brecce ofiolitiche), tendono a perdere la loro continuità nella porzione settentrionale dello stesso, laddove le condizioni strutturali determinano l’affioramento in superficie degli ammassi a comportamento “plastico”. non è noto, allo stato attuale, se al movimento abbia contribuito la presenza della superficie di sovrascorrimento fra l’unità di m. porcile (argille a palombini) e l’unità di colli-tavarone (formazione di collitavarone) (fig. 3), immergente verso ovest e disposta, quindi, sfavorevolmente alla stabilità. a tale riguardo le evidenze morfologiche sembrerebbero indicare uno spostamento del crinale (tratto fra la sella a s di m. chiappozzo e il passo del biscia) ma l’effetto potrebbe essere dovuto all’arretramento dello stesso a causa dell’intensa erosione che interessa la testata della val di vara. detta superficie di sovrascorrimento, tuttavia, potrebbe aver rivestito un ruolo fondamentale sotto il profilo idrogeologico, costituendo una via preferenziale di infiltrazione e scorrimento idrico in profondità. nell’ottica prospettata, la depressione del piano di oneto può essere interpretata come il riempimento di un trench, con allungamento parallelo al crinale (no – se), colmato da materiale limoso argilloso derivante dal dilavamento dei versanti circostanti. riteniamo che solo il suo allargamento verso oso, dove sembra accertata la presenza nel sottosuolo dei calcari a calpionelle, potrebbe essere imputato a fenomeni carsici ed erosivi. ringraziamenti si ringrazia il dott. marino sorriso-valvo per la revisione critica del manoscritto. 54 fig. 7 il piano di oneto (vista da nw). e’ visibile, sulla sinistra, la dorsale di costa ricasola. the piano di oneto (from the nw). the ridge of costa ricasola is visible on the left. l. carobene & a. cevasco 55 f ig . 8 s e zi o n e g e o lo g ic a t ra sv e rs a le d e l p ia n o d i o n e to ( la t ra c c ia è s e g n a ta i n f ig . 6 ). l e g e n d a : 1 ) c o p e rt u re d e tr it ic h e q u a te rn a ri e ; 2 ) c a lc a ri a c a lp io n e lle ; 3 ) d ia sp ri ; 4 ) b a sa lt i e b re c c e a ss o c ia te ; 5 ) lin e a m e n ti t e tt o n ic i. g e o lo g ic al c ro ss -s e c ti o n o f th e p ia n o d i o n e to ( th e t ra c e is in d ic at e d in f ig . 6 ). l e g e n d : 1 ) q u at e rn ar y d e tr it al c o ve r; 2 ) c al p io n e lle l im e st o n e s; 3 ) ja sp e rs ; 4 ) b as al ts a n d a ss o c ia te d b re c c ia s; 5 ) te c to n ic a lig n m e n ts . f ig . 9 s e zi o n e g e o lo g ic a l o n g it u d in a le d e l p ia n o d i o n e to ( la t ra c c ia è s e g n a ta i n f ig . 6 ). l e g e n d a : 1 ) c o p e rt u re d e tr it ic h e q u a te rn a ri e ; 2 ) a rg ill e a p a lo m b in i; 3 ) c a lc a ri a c a lp io n e lle ; 4 ) b a sa lt i e b re c c e a ss o c ia te ; 5 ) f o rm a zi o n e d i c o lli -t a va ro n e ; 6 ) tr a c c ia d e l p ia n o a ss ia le d e lla m e g a p ie g a c o ri c a ta d e lla v a l g ra ve g lia ; 7 ) so vr a sc o rr im e n ti ; 8 ) lin e a m e n ti t e tt o n ic i; 9 ) lin e e d i r o ttu ra d e l v e rs a n te d o vu te a lla d e fo rm a zi o n e g ra vi ta ti va p ro fo n d a d i v e rs a n te . l o n g it u d in al g e o lo g ic al s e c ti o n o f th e p ia n o d i o n e to ( th e t ra c e is in d ic at e d in f ig . 6 ). l e g e n d : 1 ) q u at e rn ar y d e tr it al c o ve r; 2 ) p al o m b in i c la ys ; 3 ) c al p io n e lle l im e st o n e s; 4 ) b as al ts a n d a ss o c ia te d b re c c ia s; 5 ) c o lli -t av ar o n e f o rm at io n ; 6 ) tr ac e o f th e h o ri zo n ta l a xi al p la n e o f th e m e g af o ld o f v al g ra ve g lia ; 7 ) th ru st s; 8 ) te c to n ic a lig n m e n ts ; 9 ) sl o p e f ra c tu re li n e s d u e t o d g sd . una deformazione gravitativa profonda ... lavori citati abbate e., bortolotti v., galbiati b. & principi g. 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(1979) approccio metodologico per l’elaborazione del piano di bacino del t.bisagno: le indagini geologiche. atti seminario su la pianificazione di bacino. c.n.r., p.f. conservazione del suolo; ist. idraulica univ. di genovaregione liguria, genova, 1979. provincia di genova (2003) carta della franosità reale (scala 1:10.000). piano di bacino, ambito 16. regione liguria (2002) note illustrative e carta geologica con elementi di geomorfologia – bargagli – tavoletta n° 214.3 (scala 1:25.000). regione liguria (2006) carta geologica regionale (carg) sc. 1:25000 lavagna tav. 232.4. http://ecozero.liguriainrete.it rovereto g. (1904) geomorfologia delle valli liguri. atti r. univ. genova, 18, 215 pp. rovereto g. (1939) liguria geologica. mem. soc. geol. it., 2, 104 – 118 sorriso-valvo m. (1979) trench features on steepseded ridges, aspromonte, calabria, italy . proceeds. polish-italian seminar on superficial mass movements in mountain regions, szymbark, 1979, may: 98-109, institut meteorologii i gospodarki wodnej, warszawa. sorriso-valvo m. (1984) atti del i seminario ”deformazioni gravitative profonde di versante” — presentazione.boll. soc. geol. it., 103, 667-669. sorriso-valvo m. (1988) studi sulle deformazionii gravitative profonde di versante in italia. mem. soc. geol. it., 41, 877-888. sorriso-valvo m. (1995) considerazioni sul limite tra deformazione gravitativa profonda di versante e frana.mem. soc. geol. it., 50, 179-185. 56 ms. ricevuto il 20 gennaio 2007 testo definitivo ricevuto il 20 febbraio 2007 ms. received: january 20, 2007 final text received: february 20, 2007 l. carobene & a. cevasco imp.iannace uu//tthh ddaattiinngg aanndd ggeeoocchheemmiissttrryy ooff ccaarrbboonnaattee ccoonnccrreettiioonnss aassssoocciiaatteedd wwiitthh uuppppeerr pplleeiissttoocceennee ffoossssiill sshhoorreelliinneess ooff tthhee ssoorrrreennttoo ppeenniinnssuullaa ((ccoonnccaa ddeeii mmaarriinnii,, ssoouutthheerrnn iittaallyy)) aalleessssaannddrroo iiaannnnaaccee11,, ppaaoollaa rroommaannoo11 && ppaaoollaa ttuucccciimmeeii22 1dipartimento di scienze della terra, università di napoli federico ii, napoli, italia, aleianna@unina.it, paromano@unina.it; 2dipartimento di scienze geologiche, università "roma tre", roma, italia, tuccimei@uniroma3.it abstract u-series dating and geochemical analyses were performed on carbonate concretions in order to put chronological constraints on the associated fossil shorelines. in particular, samples were taken from concretions found at conca dei marini cape where former shorelines ascribed to the upper pleistocene are present. from the chronological data the height of sea level during highstands of late pleistocene is inferred; moreover, due to the tectonic stability of the area the estimated height could be taken as a close approximation of eustatic sea level position. a +3.5 m a.s.l. sea level highstand which occurred during the end of oxygen isotopic stage (ois) 5e was recognised by the u/th age and elevation of the concretion covering a wave-cut platform. furthermore, new interpretations for more recent sea level highstands were obtained by analyses performed on two calcitic concretions associated with a marine biocalcarenite. they indicate that the sea level at the end of ois 3 was close to the present day one; such a conclusion disagrees with the generally accepted sea levl position derived from proxy data taken from oceanic cores while it agrees with recent chronological data obtained from marine deposits in the gulf of taranto (southern italy). riassunto in due siti della penisola sorrentina , presso il capo di conca dei marini, sono state rinvenute alcune concrezioni carbonatiche in associazione con depositi e forme marine ascritte in letteratura agli stazionamenti alti del livello marino correlati con lo stadio 5 della stratigrafia basata sugli isotopi dell'ossigeno. su queste concrezioni sono state eseguite datazioni u/th al fine di ottenere ulteriori vincoli cronologici (limiti ante quem o post quem) per la genesi delle linee di riva, ed analisi sedimentologiche e geochimiche indirizzate alla determinazione del loro ambiente diagenetico. le condizioni di stabilità tettonica tardo quaternaria caratterizzanti l'area in studio hanno consentito, inoltre, di porre in relazione la posizione altimetrica dei depositi e delle forme cronologicamente inquadrati ad altrettante posizioni eustatiche del livello marino durante gli stadi isotopici 5 e 3 del pleistocene superiore. fra i risultati più interessanti si segnalano quelli ottenuti da una concrezione laminare datata al sottostadio 5d che ricopre una piattaforma di abrasione posta a +3,5 m s.l.m., la cui genesi va così inquadrata nella parte finale del sottostadio 5e, e le datazioni di due concrezioni calcitiche che si intercalano ad una biocalcarenite marina a + 4 m s.l.m. queste ultime, datate allo stadio3, suggeriscono una posizione del livello marino per quel periodo prossima al livello marino odierno; tale conclusione da un lato contrasta con quanto sinora proposto in letteratura sulla base di dati indiretti ottenuti da carote oceaniche, d'altra parte è in accordo con recenti dati ottenuti su depositi marini affioranti sulle coste del golfo di taranto. key words: emerged shorelines, calcareous concretions, geochemistry, u-series data, upper pleistocene, southern italy. parole chiave: linee di riva, concrezioni calcaree, geochimica, datazioni u/th, pleistocene superiore, italia meridionale. il quaternario italian journal of quaternary sciences 1166(1bis), 2003, 49-54 11.. iinnttrroodduuccttiioonn the sorrento promontory is a ne-sw trending horst facing capri island along the coast of the campania region (fig.1). highly resistant rocks – carbonates of meso-cenozoic age – displaced by normal faults in structural blocks constitute the promontory. as such, the peninsula is characterised by a structure-controlled type of coast with high and rectilinear sea cliffs interrupted by angular plan-shaped bays and pocket beaches. offshore, plunging cliffs alternating with narrow coastal benches are generally present. similarly, the quaternary fossil shorelines of the peninsula are represented by scattered and small remnants of marine terraces and by scarce outcrops of coarse-textured beach deposits patched onto the bedrock and usually barren. there are a very few sites where fossiliferous pleistocene marine deposits are present such as the well known ieranto and conca dei marini bays, where eutyrrhenian marine deposits were pointed out (brancaccio et al., 1978). in this paper we present new chronological data on the upper pleistocene fossil shorelines of the sorrento peninsula. they have been obtained by useries data performed on carbonate concretions which we have found closely or directly associated with some sea level stand indicators, both of erosional and depositional origin, in conca dei marini area. 22.. ggeeoommoorrpphhoollooggyy,, ssttrraattiiggrraapphhyy aanndd sseeddiimmeennttoollooggyy two sites of conca dei marini promontory (site i and site ii in fig.1) have been studied in detail in this paper. the upper pleistocene shorelines are represented by patches of marine deposits and by bioerosive notches and emerged platforms, located at elevation 50 a. iannace, p. romano & p. tuccimei between +8 and +1.5 m. they were studied in brancaccio et al. (1978), cinque & romano (1990), riccio et al. (2001). in site i several carbonate concretions associated with a + 8 m high notch have been found (fig.2). the concretions are finely laminated and fill bowl-like cavities present all along the notch concavity. microscopically, the concretions consist of alternation of microsparitic laminae. xrd analyses revealed the presence of some aragonite together with calcite. the origin of the cavities and carbonated infilling appears very problematic. possibly, the cavities originated as lithophaga sp. burrows and were subsequently enlarged by chemical weathering. the former studies carried fig. 1 geological scheme of the sorrento peninsula with the locations of the conca dei marini promontory and of the site i and site ii bays (after riccio et al., 2001 modified). fig. 2 geological section of site i bay (after riccio et al., 2001 modified). the photographs show a detailed and a complete view of the concretions present all along the + 8 m high notch. 51u/th dating and geochemistry ... fig. 3 geological section of site ii bay. for details of the concretions see fig. 4. fig. 4 details of the calcareous concretions associated with marine deposits or erosional morphologies at site ii bay. a) the concretion lying onto the +3.5/4 emerged bench, 2/4 cm thick. b) the concretions cementing the upper part of a marine calcarenite, 1/2 cm thick. 52 out in the area (brancaccio et al., 1978; riccio et al., 2001) indicated an euthyrrenian age of the + 8 m notch because it is closely associated with a marine deposit with cladocora coespitosa. in site ii different generations of calcareous concretions were found closely or directly associated with emerged shorelines (fig. 3). some platy, laminated calcitic concretions (fig.4a) lie onto a +3.5/4 m high wavecut platform which was tentatively ascribed to a late oi substage 5e sea level stand by riccio et al. (2001). other generations of concretions intercalated in the upper part of a marine calcarenite at +4 m a.s.l. (fig. 3 and fig. 4b) were observed. the marine deposit covers the +3.5/4 m high emerged platform and there it is only some 60 cm thick; laterally, instead, the deposit thickens to some 100 cm because it fills a sheltered niche whose bottom is 1 m lower than the terrace and is cut directly into the mesozoic carbonates of the substrate. the deposits are distinctly clinostratified and dip landward with a fan-shaped bedding which progressively compensates the difference in accomodation space between the terrace and the niche. this demonstrates that the protected niche was filled gravitationally by sediments coming from the sea-ward side and washed over the threshold represented by the bench. the sediments, as reported in riccio et al. (2001), consist of a matrix-free coarse calcarenite to calcirudite. the part of deposits closer to the sea is distinctly coarser, with single grains reaching some cm in diameter. grains are subrounded and show a good sorting within each layer. they consist mainly of bioclasts and lithoclasts of coarse-crystalline dolomites. only one layer, at 80 cm, consist mostly of more angular and reddened lithoclasts. the bioclasts are represented mainly by fragments of articulate and inarticulate bivalvs, gastropods, bryozoan and echinoderms and of red algae. frequent are also micritic grains of unknown origin. the deposit is generally highly porous and crumbly because of a very low degree of cementation. in fact, in the thin section, only an irregular, discontinuous rim of limpid, equant calcite cement is present showing frequently meniscus textures. only a few layers in the upper part of the deposits are heavily cemented by several laminated carbonate concrections. the concretions are represented by several mm thick laminated layers consisting exclusively of precipitated carbonate which interrupt the sedimentary layering (fig 4b and 5). however, there are also calcarenite layers made harder by the presence of the same carbonate precipitate covering the sigle grains. the geometric relations between cement and sediment layers demonstrate that most of the cementation took place during deposition. moreover, it is clear from field relations that for the latest concrections, downward, stalactitic growth on cavity floor was contemporaneous with upward growth on the sediment surface, probably as a flowstone. the microstructures are characterised by alternating laminae of spar and microspar often showing the presence of fibrous structures due to the crystallographic continuity of single crystals of each superposed lamina. this especially occurs when the laminae are not planar but form domes and arches. in the case of upward growth on the sediment surface these structures are comparable to those of stromatolites according to the definition of de micco & hardie (1994). otherwise, they are typical of coconut calcite in stalactitic growth. these concrections are morphologically comparable to many spleothems but also to some carbonates formed in special conditions in supersaturated marine waters, as suggested by riccio et al. (2001). 33.. ggeeoocchheemmiissttrryy the several carbonate concrections at conca dei marini are the only available material to constrain cronologically the associated sediments and erosional features. to this aim, several samples have been collected from: the concrections cementing the upper part of the biocalcarenite at site ii, both in the stalactitic (samples cm5) and stalagmitic (sample cm4) portions; the problematic circular concrections partly covering the +8 m notch at site i (sample cm1); the concrection covering the coastal bench at 3.5-4 m at site ii (samples cm6); from the collected material, four samples have been analysed by u-series disequilibria, nine for o and c stable isotopes. the list of samples and results are shown in tables 1 and 2. for u-series disequilibria measurements, samples were crushed into several-millimetre-diameter pieces with a stainless-steel chisel. these fragments were examined under a binocular microscope and any piece that a. iannace, p. romano & p. tuccimei fig 5 details of the stalactitic (cm4) and the stalagmitic (cm5) portions of the concrections cementing the marine calcarenite at site ii. 53 showed signs of secondary alteration was discarded. the remaining portion was ultrasonically cleaned in distilled water twice. the analytical procedure used for u and th separation was that reported by bischoff et al. (1988). three to six gram samples were spiked with a 228th + 232u tracer (in secular equilibrium) and activity ratios were counted in an eg&g ortec 920-8 alpha spectrometer system. the ages and the initial 234u/238u activity ratios were calculated by means of isoplot, a plotting and regression program designed by ludwig (1994) for radiogenic-isotope data. the uranium contents, the activity ratios and the calculated 230th ages are listed in table 1; all errors are reported as 1 sigma. for o and c isotope ratios measurements, a few mg of powder have been obtained with a dental drill from areas which are exclusively formed of precipitated carbonates. carbonate powders were reacted with 100% phosphoric acid at 75 °c and analysed in a carbonate preparation line connected to a finnigan mat 252 mass spectrometer. the analyses have been carried out at the stable isotope laboratory of erlangen university (germany). results are shown in table 2. all the subsamples extracted from cm4 and cm5 samples have δ13c and δ18o isotope values ranging from -3,7 to -8,1 and from -2,2 to -3,5 (pdb) respectively. these values, especially the c-isotope ratios, indicate precipitation from meteoric waters. the relatively marked variation within the sample set cannot be explained precisely and has to be attributed to temperature and compositional variation in the parent fluid, both possibly linked to seasonal or climatic factors. the initial 234u/238u activity ratios calculated from two samples of the same concretions are 1.05 and 1.07, both not consistent with the average uranium composition of the oceans (about 1.15). the only isotopically different carbonate is represented by the cavity-filling concretions found at +8 m at site i (cm1). in fact, a single measurement performed on this material gave δ18o and δ13c values of -0.1 and -0.8 (pdb) respectively, distinctly heavier than the other samples. part of this difference can be attributed to the presence of aragonite in these concretions, which has a slightly higher fractionation factor with respect to calcite, both for carbon (1.8 per mil) and oxygen (0.6 per mil). however, the measured value implies at least a partial contribution of marine waters during precipitation. a simple evaporation effect on meteoric waters can be excluded because this would have raised the measured o-isotopes ratios but not the c-isotopes ones. this interpretation is further strengthened by u-geochemistry. in fact, both u-content and 234u/238u activity ratios are higher than in the cm 4 and 5 samples, this again suggesting a marine contribution in the precipitation of these concrections. for cm6, sample u-data suggest a meteoric origin and a single δ18o and δ13c measurement seems to confirm this. 44.. ddiissccuussssiioonn the chronological data obtained at conca dei marini (table 1) permit to infer the height of sea-level during high-stands of the late pleistocene. the estimated height can be taken as a close approximation of eustatic sea level positions. in fact, as pointed out in brancaccio et al. (1978) and riccio et al. (2001), the conca dei marini sites have suffered a maximum uplift of 1.5 m since the eutyrrhenian, corresponding to a mean rate of 10-2 mm/a. the calculated age for the concrection covering the +3.5 m bench (cm6) is 109.1 ka (table 1), which falls within oi substage 5d (martinson et al. 1987). this only represents an upper limit for the age of the bench. the lower one is the eutyrrhenian because the bench can be correlated to a +3.5 notch cutting the cladocora deposit (see fig. 2), as discussed in riccio et al. (2001). thus, the geochronological data confirm the hypothesis that this highstand occurred during late substage 5e. however, the ages of the other concrections proviu/th dating and geochemistry ... table 1 u-series data, mineralogy and inferred isotope stage of samples from conca dei marini (italy). quoted ratios are activity ratios and errors are expressed as 1 sigma. (234u/238u)init. represents the initial uranium ratio. sample mineralogy u ppm (230th/232th) (234u/238u) (230th/234u) (234u/238u)init. age (ka) stage cm1 aragonite+ 3.439 ± 0.098 25 ± 1 1.126 ± 0.014 0.387 ± 0,015 1.146 ± 0.016 52.7 ± 2.6 3 mg calcite cm4 calcite 1.878 ± 0.035 75 ± 10 1.059 ± 0.017 0.424 ± 0.012 1.07 ± 0.02 59.6 ± 2.2 3 -4 cm5 calcite 1.211 ± 0.022 34 ± 3 1.043 ± 0.017 0.397 ± 0.011 1.050 ± 0.020 54.8 ± 2 3 cm6 calcite 0.514 ± 0.016 856 ± 792 1.057 ± 0.034 0.638 ± 0.025 1.078 ± 0.046 109.1 ± 7.3 5d table 2 c and o isotope ratios measured on conca dei marini concretions. sample δ13c std.dev. δ18o std.dev cm1 -0.8 0.02 -0.2 0.02 cm 4a -7.2 0.03 -3.0 0.03 cm 4b -8.1 0.02 -3.5 0.02 cm 4c -5.5 0.02 -3.2 0.04 cm 4d -5.5 0.03 -3.3 0.06 cm 5a -5.7 0.02 -2.5 0.03 cm 5b -6.1 0.02 -2.4 0.05 cm 5c -3.7 0.02 -2.2 0.06 cm 5d -5.5 0.01 -2.6 0.02 cm 6 -6.5 0.04 -4.1 0.04 54 de new interpretations for more recent sea level highstands. in fact, u-series data indicate an age of approximately 54-59 ka for the cm 5 and cm 4 concrections respectively (table 1), which can be considered as an estimate of the age of the bioclastic deposits. these ages correspond to the beginning of ois 3. the sedimentological evidence indicates clearly that the deposits formed as a backshore deposit washed over the bench into a sheltered niche on the rocky coast during storms. considering the height of the marine calcarenite, this would indicate that the contemporaneous sea level was not so far from the present day one. such a conclusion disagrees with the largely accepted assumption that the sea level during the whole ois 3 was some tens of meter below the present one. this conclusion is generally derived from proxy data, specifically by assuming a more or less direct relationship between o-isotope values in oceanic foraminifers and ice-volume (chappel & shakcleton, 1986). however, recent research in the mediterranean area has found a little sedimentological evidence, supported by geochronological data, of a highstand above the present sea level during ois 3 (belluomini et al., 2002). our data provide further support to these findings. the uand o-c isotope geochemistry of the problematic concrections of + 7/8 m at site 1 represents a further possible evidence that sea level was close to the present one during ois 3. in fact, the calculated age is 52 ka and u content and o and c isotope ratios indicate a precipitation by a fluid with a partial marine contribution. a possible explanation is that sea water came from marine spray over the rocky cliffs. we think that the data of conca dei marini and those reported by belluomini et al (2002) impose further research in other areas, coupled with a critical review of published data concerned with recent sea level highstands, in order to definitively verify the validity of the generally accepted late pleistocene sea level curves. aacckknnoowwlleeddggeemmeennttss this paper was financially supported by cnr n.99.00646 ct05 grant: "ricostruzione delle principali variazioni indotte sui sistemi geomorfici dalle flutuazioni climatiche tardo quaternarie e storiche", local chief scientist prof. a. cinque. rreeffeerreenncceess belluomini g., caldara m., casini c., cerasoli m., mandra l., mastronuzzi g., palmentola g., sansò p., tuccimei p. & vesica p.l. (2002) the age of late pleistocene shorelines and tectonic activity of taranto area, southern italy. quaternary science reviews, 2211, 525-547. bishoff j.l., rosenbauer r.j., tavoso a. & lumley h. (1988). a test of uranium-series dating of fossil tooth enamel: results from tautavel cave, france. applied geochemistry, 33, 145-151. brancaccio l., capaldi g., cinque a., pece r. & sgrosso i. (1978) 230th-238u dating of corals from a tyrrhenian beach in sorrentine peninsula (southern italy) quaternaria, 2200, 175-183. chappel j. & shackleton n.j. (1986) oxygen isotopes and sea level. nature, 332244, 137-140. cinque a. & romano p. (1990) segnalazione di nuove evidenze di antiche linee di riva in penisola sorrentina (campania) geogr. fis. dinam. quat., 1133 (1), 23-36. demicco r. v. & hardie l. a. (1994) sedimentary structures and early diagenetic features of swallow marine carbonate deposits. soc. of econom. paleontol. and mineralog. atlas series, 11, tulsa, 265 pp. ludwig k.r. (1994). isoplot. a plotting and regression program for radiogenic-isotope data. version 2.75. u.s. geological survey, open-file report, 91-445. martinson d.g., pisias n.g., hays j.d., imbrie j., moore t.c. & shackleton n.j. (1987) age dating and the orbital theory of the ice ages: development of a high resolution 0-300,000 year chronology. quaternary research, 2277, 1-29. riccio a., riggio f. & romano p. (2001) sea level fluctuation during oxygen isotope stage 5: new data from fossil shorelines in the sorrento peninsula (southern italy) z. geomorph. n.f., 4455 (1), 121-137. a. iannace, p. romano & p. tuccimei imp.paiero-monegato tthhee pplleeiissttoocceennee eevvoolluuttiioonn ooff aarrzziinnoo aalllluuvviiaall ffaann aanndd wweesstteerrnn ppaarrtt ooff ttaagglliiaammeennttoo mmoorraaiinniicc aammpphhiitthheeaattrree ((ffrriiuullii,, nnee iittaallyy)) ggiioovvaannnnii ppaaiieerroo11 && ggiioovvaannnnii mmoonneeggaattoo11 1dipartimento di georisorse e territorio, università di udine, via cotonificio 114, i-33100 udine. abstract the pleistocene evolution of arzino alluvial fan and western part of tagliamento morainic amphitheatre (friuli, ne italy) the geologic survey of the sheet 065 “maniago” (carg project) allowed to gain founded data for attempting a reconstruction of pleistocene evolution of this portion of friuli piedmont plain, located in left hydrographic slope of tagliamento river. units recognised by bounding discontinuity are unconformity-bounded stratigraphic units in the meaning used in carg project. eight units have been distinguished: four related to arzino alluvial fan, three to tagliamento morainic amphitheatre and one to ragogna hill southern slope evolution. these units outcrop along tagliamento left slope and inside ponte brook valley. arzino alluvial fan is made by stratified gravel and sandy deposits, tagliamento basin units are made by glacial (lodgement till and melt-out till) and fluvioglacial sediments (mainly sandy gravel), while the units of ragogna hill southern slope are colluvial (muddy diamicton) and alluvial (sandy gravel and sand). relationships between arzino alluvial fan and tagliamento endmorain system, happened during quaternary age, let to understand the relative chronology of events, erosive and sedimentary, that has interested pinzano narrow area during this time span. during early and middle pleistocene through it arzino stream flew down and built an alluvial fan; then from middle pleistocene glacial advances in tagliamento basin began to interfere with alluvial fan till it was completely covered during last glacial maximum in tagliamento basin, for which a find provided the age 19.075±160 14c yr bp. as regards older units, probably many events are juxtaposed without recognisable and classifiable bounding surfaces, whereas chronological reconstruction becomes more reliable for late pleistocene units. riassunto l’evoluzione pleistocenica del conoide alluvionale dell’arzino e della parte occidentale dell’anfiteatro morenico del tagliamento (friuli, italia ne) la presente nota riguarda la porzione di pianura pedemontana friulana posta in sinistra idrografica del fiume tagliamento presso ragogna, dove affiora una successione di unità di età quaternaria, caratterizzabili in base alle discontinuità che le delimitano ed alla composizione litologica dei clasti. grazie ai nuovi dati acquisiti durante il rilevamento geologico del foglio 065 “maniago” (progetto carg) i depositi di età quaternaria sono stati distinti utilizzando come unità di riferimento le unconformity-bounded stratigraphic units con il significato utilizzato per la cartografia del progetto carg. vengono qui descritte otto unità: quattro relative al conoide alluvionale del torrente arzino, tre dell’anfiteatro morenico del tagliamento ed una legata all’evoluzione del versante meridionale del monte di ragogna. tali unità affiorano con buona continuità nella scarpata sinistra del fiume tagliamento tra san pietro e aonedis e all’interno della valle del rio ponte. i depositi relativi al conoide del torrente arzino sono caratterizzati da ghiaie e sabbie variamente stratificate e classate; quelli relativi al bacino del tagliamento sono di origine glaciale (till di alloggiamento e di ablazione s.l.) e fluvioglaciale (in prevalenza ghiaie sabbiose); mentre quelli del versante meridionale del monte di ragogna sono di origine colluviale (diamicton limosoargilloso) ed alluvionale (ghiaie sabbiose e sabbie). le relazioni tra il conoide alluvionale dell’arzino e i depositi legati alle avanzate glaciali nel bacino del tagliamento hanno favorito la comprensione della cronologia relativa degli eventi, erosivi e sedimentari, che hanno interessato l’area presso la stretta di pinzano durante il quaternario. durante il pleistocene inferiore ed in parte del medio per essa transitavano le acque del torrente arzino, che ha costruito un conoide alluvionale che aveva qui il proprio apice. a partire dal pleistocene medio i depositi legati alle avanzate del ghiacciaio del tagliamento hanno cominciato ad interferire con l’aggradazione del conoide il quale è stato sepolto interamente durante l’ultimo episodio glaciale, per il quale un reperto ha fornito la data 19.075±160 14c a bp. nel caso delle unità più antiche probabilmente si sovrappongono più episodi sedimentari senza superfici limite riconoscibili e classificabili; mentre per le unità del pleistocene superiore la ricostruzione cronologica si fa più affidabile. keywords: alluvial fan, tagliamento morainic amphitheatre, pleistocene, arzino, friuli. parole chiave: conoide alluvionale, anfiteatro morenico del tagliamento, pleistocene, arzino, friuli. il quaternario italian journal of quaternary sciences 1166(1), 2003, 185-193 11.. iinnttrroodduuccttiioonn the study area (fig. 1) includes a part of piedmont plain between tagliamento river, ragogna hill and western ridges of the morainic amphitheatre. tagliamento river flows in the last stretch of the valley northern-side of ragogna hill, where arzino stream flows into tagliamento, that, after crossing pinzano narrow, flows out in the plain where it shaped the late pleistocene plain into a slope 60÷70 m high. here a complex of quaternary units outcrops; this is the main object of this paper. continuity of tagliamento's left slope is cut off by three tributary brooks, namely mordaro, ponte and fos (fig. 1). in particular in ponte brook's slopes, about 2 km long, and in fos brook's ones, about 1.1 km long, many outcrops allow to observe in the third dimension units outcropping in tagliamento's left slope and to correlate them to tagliamento amphitheatre ones. this complex morainic amphitheatre witnessed that, during pleistocene times, tagliamento valley was the site of a glacier that many times flew out southward in the friuli piedmont plain. the portion of the glacier interesting this area corresponded to "san daniele" lobe, that flew inside the sag between ragogna hill and susans hill. morainic ridges, in the southern side of ragogna hill, are set against the versant, then they are continuos eastward as far as san daniele village, where are interrupted by the valley of corno stream, originate by one of the main and lasting meltwater streams of last glacier 186 g. paiero & g. monegato fig. 1 geologic sketch map of the study area and its location (modified after m.u.r.s.t., 1997). carta geologica schematica dell’area studiata e sua ubicazione (modificato da m.u.r.s.t., 1997). (feruglio, 1920; comel, 1955; croce & vaia, 1985). pre-quaternary substratum outcropping in this area is given by montello conglomerate (massari et alii, 1986), an upper tortonian lower messinian terrigenous sequence and by the osoppo conglomerate (dalla vecchia & rustioni, 1996; zanferrari et alii, in prep.), an upper messinian – pliocene continental conglomeratic sequence . study area lies on the sse-verging arba-ragogna thrust (fig. 1), the more external thrust of the eastern southalpine chain front (zanferrari et alii, 2002; zanferrari et alii, in prep.). such structure is characterised by tectonic activity from upper miocene to present (zanferrari et alii, in prep.). this paper is aimed at illustrating the quaternary succession of a part of friuli piedmont plain (ne italy). in particular the complex sequence of existing sedimentary units, so far undervalued by detail stratigraphic studies, was sorted out, in order to reconstruct, downflow of pinzano narrow, the evolution of arzino alluvial fan and its relationships with glacial and fluvioglacial units of tagliamento. this study uses new data gained during cargfvg project's geological survey for the new 065 "maniago" geologic sheet at the scale 1:50.000. 22.. pprreevviioouuss ssttuuddiieess early authors surveyed quaternary deposits of this area since late ‘800 (taramelli, 1875; tellini, 1892; penck & brückner, 1909). first official geological map was "udine" sheet of carta geologica delle tre venezie at the scale 1:100.000 (feruglio, 1925; 1929b). in this map the glacial deposits, located in the study area, have a würm age; older deposits given to riss glacial age are marked in the borgo di mezzo terrace slopes (tellini, 1892; feruglio, 1929a) and recognised by the presence of a strongly weathered level of gravel, called ferretto, between these glacial units. later authors accepted feruglio’s assumptions for amphitheatre glacial units, except of sacco (1937). the latter gave a mindel? age to feruglio's riss one, for the strong reworking of outer morainic ridges; a riss age to higher morainic ridge, that feruglio gave to würm acme, since riss glaciation were considered the longest; and a würm age to inner ridges because less developed. whole tagliamento morainic amphitheatre was studied also by gortani (1959), carraro & petrucci (1977; 1982) 187the pleistocene evolution of arzino ... and croce & vaia (1985). whereas the presence of a pleistocene glacier inside arzino valley was witnessed by glacial deposits only in the head of valley; this glacier was probably a lobe of tagliamento glacier, overflowing through chiampón and chianzután saddles (tellini, 1892; penck & brückner, 1909; zenari, 1927; sacco, 1937; comel, 1956; gortani, 1959). the deposits of tagliamento left slope were generally studied joined with amphitheatre ones. the deposits of amphitheatre are directly related to glacial advances evidenced by morainic ridges; only di bernardo et alii (1998) gave a short stratigraphy of the fluvial succession, ascribing all them to tagliamento basin. 33.. mmeetthhooddss aimed at planning and addressing properly the field work, the study area has been previously studied by interpreting aerial images and analysing the microrelief on topographic maps (scale 1:10.000 and 1:5.000) with 1 m contour lines. each outcrop has been mapped and the observed features were recorded for the geologic data base of carg project (zanferrari et alii, 2000), according to a modified version of the guidelines after baggio et alii (1997). sedimentary facies and discontinuities were examined in detail to distinguish the elements of the sedimentary architecture. the facies classifications, after miall (1996) for fluvial deposits and eyles et alii (1983) for glacial deposits, have been used; for classification of the latter bini & orombelli (1988) review has been adopted. the bounding surfaces classification after miall (1996) (tab. 1), with boyce & eyles (2000) review for glacial deposits, has been used. hierarchization of bounding surfaces was above all obtained using the evolution degree of the soils developed during their shaping. units obtained are unconformity-bounded stratigraphic units (issc, 1994), in the meaning of carg project (zanferrari et alii, in prep.), and they were split up by relationship between bounding surfaces, litofacies, petrographic nature of clasts and sedimentary body alteration and deformation. blair & mcpherson (1999) grain-size scale was adopted, while the given color for sediments, weathered horizons and soils refers to the munsell soil color charts. radiocarbon data were obtained at radiocarbon lab of “dipartimento di scienze della terra” of "la sapienza" university of rome. tab. 1 classification of bounding surfaces by miall (1966) / classificazione delle superfici limite secondo miall (1966). rraannkk ddeeffiinniittiioonn ttiimmee ssccaallee ooff pprroocceessss ((aa)) 1st order set bounding surface; microform, minor erosion 10-5 10-4 10-3 2nd order coset bounding surface; mesoform 10-2 – 10-1 3rd order dipping 5-20° in direction of accretion; macroform growth increment 100 101 4th order minor channel scour, flat surface bounding floodplain elements; immature paleosol 102103 5th order flat to concave-up channel base; mature paleosol 103 104 6th order flat, regionally extensive or base of incised valley 104 105 7th order sequence boundary; flat, regionally extensive, or base of incised valley 105 106 8th order regional disconformity, basin fill complex 106 107 188 a critical element for fixing units was clasts' petrographic analysis, that let to distinguish deposits on their source basin, because the two watercourses whose sediments characterised the area have a lithologic different source basin: light and monochromatic carbonate deposits, with dolomites and limestones more than 95%, as concerning arzino stream; polychromatic carbonates, with remarkable siliceous and volcanic clasts portion and presence of clasts of metamorphics, as concerning tagliamento river. in the investigated area two different main sites can be distinguished: rio ponte section (a-a’ in fig. 1), a glacial sequence heteropic with ragogna hill hillslope sediments, whose most complete sections crop out inside ponte brook valley, where it has an overall thickness of 90 m, even if some isolated boulders were found 50 m higher than morainic ridges. san pietro aonedis section (b-b’ in fig. 1), where an alluvial sequence of 60-70 m thick is exposed in left fluvial slope of tagliamento river from pinzano bridge to aonedis. some stratigraphic units are present in both sections because their deposits are phisically continuous from one to another. 44.. rriioo ppoonnttee sseeccttiioonn the rio ponte section is 500 m long and 150 m high. it is located in the head of ponte brook valley. here many units crop out (zanferrari et alii, in prep.) (fig. 2): the complex rio ponte unit, having source from geomorphologic evolution of southern side of ragogna hill, three different glacial units: plaino, santa margherita and canodusso synthems, related to tagliamento glacier expansions. 44..11.. rriioo ppoonnttee uunniitt ((uurrpp)): this unit outcrops only inside ponte brook incision and it is made by different sedimentary bodies with an average dip of strata of 25-30 degrees southward; unit has been divided in the following facies: massive to stratified gravel (gci-gh), locally cemented; clasts are subangular and carbonate, resulted from montello conglomerate and osoppo conglomerate erosion; texture is clast-supported to matrix-supported; matrix is muddy and weathered, having a strong brown (7.5yr4/6) color. interstratified sandstones are present, laminated to massive, about 50 cm thick. these are deposits related to small fans originated from ragogna hill southern side incisions and active before the deposition of glacial units. muddy massive diamicton, matrix-supported (dmm), made of rounded, strongly alterated clasts; carbonate lithologies are absent; muddy matrix is weathered and has a yellowish red (5y5/6) color. this facies has a variable thickness, from less than 50 cm to some meters, it is interbedded with gravel facies. its origin is probably colluvial from weathering process interesting osoppo conglomerate and early pleistocene tagliamento basin deposits. basal boundary is a disconformity and locally an angular unconformity of 15 degrees with the substratum. boundary existing on the top is a weathered surface on gravel facies, characterised by a paleosol 3.5 m thick, with an 1 m thick argillic horizon with a yellowish red (5yr4/6) color. 44..22.. ppllaaiinnoo ssyynntthheemm ((ppllii)):: this unit is here made by a “loose skeletal till”, characterised by isolated, weathered boulders and cobbles scattered in ragogna hill southern side, between 340 and 310 m a.s.l. this is the evidence of the older glacial expansion so far observed in tagliamento morainic amphitheatre. 44..33.. ssaannttaa mmaarrgghheerriittaa ssyynntthheemm ((ssnnmm)):: this unit, whose morphology was strongly reshaped by late pleistocene sedimentary events, is situated just next to some soft ridges outwardly to the main ridges of the amphitheatre. unit is made by a sequence of glacial deposits; in the study section they can be distinguished in: silty massive diamicton, matrix-supported and heavily consolidated (dmm), rich in chaotic clasts, from subangular to subrounded, striated and glacially shaped (flatiron and bullet shaped). matrix is silt with sand, dark yellowish brown (10yr4/5) to brownish yellow (10yr6/6). the facies presents pods and irregular shaped rafts of sorted sediment, likely originated by c o m p r e s s i o n of fine lenses in subglacial environment, and linear or cluster concentration of clasts, pebble to fine boulder-sized. the whole deposit can be defined as a subglacial lodgment till. fig. 2 schematic cross section of rio ponte section (a-ai in fig. 1). mon: montello conglomerate; osp: osoppo conglomerate; urp: rio ponte unit; pli: plaino synthem; snm: santa margherita synthem; nds: canodusso synthem; a: alluvial deposits; b: lodgment till; c: ablation till; d: “loose skeletal till”; ar: arba–ragogna thrust. sezione schematica della sezione del rio ponte (a-ai in fig. 1). mon: conglomerato del montello; osp: conglomerato di osoppo; urp: unità del rio ponte; pli: sintema di plaino; snm: sintema di santa margherita; nds: sintema di canodusso; a: depositi alluvionali; b: till d’alloggiamento; c: till di ablazione s.l.; d: “morenico scheletrico sparso”; ar: faglia arba-ragogna. g. paiero & g. monegato m a.s.l. 189 massive diamicton, matrix-supported to clast-supported (dmm-dcm), rich in subangular boulders; this deposit is normally consolidated and locally cemented; it is rich of striated clasts in a silty-sandy matrix. it can be classified as an ablation till. lodgment till is about 10 m thick; it is easily observing in ponte brook incision and in the head of fos brook valley, where is heteropic with fluvioglacial gravel (see the further on “santa margherita synthem” in “san pietro aonedis section”). whereas ablation till has maintained a thickness of 15 m, moreover it must taken to account several isolate boulders and pebbles situated at 250÷275 levels on ragogna hill and that can be relate to this unit. lower boundary is an erosion surface on rio ponte unit deposits. upper boundary with canodusso synthem is an erosion surface sometimes marked by a weathered surface having brown to strong brown (7.5yr4/4-5/6) color. 44..44.. ccaannoodduussssoo ssyynntthheemm ((nnddss)):: this unit represents last main sedimentary event in friuli piedmont plain, and is characterised by a glacial-fluvioglacial sequence morphologically evident in the whole morainic amphitheatre. in the study area these glacial deposits make up a double end morainic ridge, the outer more discontinuous and lower (quotes from 250 to 270 m), the inner more defined and higher (quotes from 260 to 300 m). fluvioglacial deposits are made by clast-supported massive gravel (gcm) to crudely bedded gravel (gh), weakly cemented, with subrounded clasts, medium pebble to boulder sized, with silty-sandy matrix. thickness is variable and not exceeding 5 m. the reworked top of these deposits makes the terraced surface on right side of ponte brook. glacial deposits can be distinguished in: silty massive diamicton, matrix-supported and heavily consolidated (dmm), rich of chaotic clasts, from subangular to subrounded, striated and glacially shaped (flat-iron and bullet shaped). matrix is made by silt with sand, dark greyish brown (2.5y5/2) to light olive brown (2.5y5/4). this facies is rich of pods and irregular shaped rafts of sorted sediment, likely originated by compression of fine lenses in subglacial environment, interbeds of thin bedded to massive silty sand and linear or cluster concentration of clasts, pebble to fine boulder-sized, are present. these elements are often glaciotectonically deformed. basal level of this deposit, because of its general deformation, can be classified as a deformation till; it can be defined as a subglacial lodgment till. massive diamicton, matrix-supported to clast-supported (dcm-dmm), normally consolidated; clasts are generally subangular, many of which are striated, granule to boulder sized; they are characteristic of tagliamento basin with very rare exotic pebble of austro-alpine gneiss; rich of striated clasts in a siltysandy matrix pale yellow (2.5y7/3) colored. it is a supraglacial ablation till. lodgment till has a kept thickness of 20 m, while ablation till has a kept thickness of 40 m. the basal boundary consists of an erosion surface over rio ponte unit and santa margherita synthem deposits; near canodusso hamlet, a sample of wood fragment was found in silty-clayey sediments next to basal surface (fig.3); this sample yielded the conventional 14c age of 1199..007755±±116600 yr bp (rome-1393). the upper boundary is the topographic surface marked by a weathered surface having dark yellowish brown (10yr4/4) to brown (7.5yr4/4) color. 55.. ssaann ppiieettrroo - aaoonneeddiiss sseeccttiioonn in san pietro aonedis section (left tagliamento fluvial slope) is displayed a series of pleistocene sedimentary bodies, laid down by watercourses flowing out from pinzano narrow, and fluvioglacial deposits connected with glacial end moraines of tagliamento amphitheatre; in this site, 4300 m long and 60-70 m high, 7 units are distinguishable (fig. 4). 55..11.. bboorrggoo ddii mmeezzzzoo ssyynntthheemm ((bbggmm)):: outcropping from pinzano narrow to ponte brook valley, it is made by a sequence of clast-supported massive gravel (gcm) to crudely-bedded gravel (gh), generally lithified, with carbonate (more than 95% of white or grey carbonate) alterated subrounded clasts, medium pebble to boulder sized. its matrix is muddy sand, altered and fig. 3 canodusso synthem lower boundary with the location of sample dated (rome-1393). snm: santa margherita synthem; nds: canodusso synthem. limite inferiore del sintema di canodusso con l’ubicazione del campione datato (rome-1393). snm: sintema di santa margherita; nds: sintema di canodusso. the pleistocene evolution of arzino ... 190 f ig . 4 a ) s ch e m a tic c ro ss s e ct io n o f s a n p ie tr o – a o n e d is s e ct io n ( b -b i in f ig . 1 , ve rt ic a l e xa g g e ra tio n x5 ), n o te d iff e re n t th ro w s ca u se d b y a rb a – r a g o g n a g ro w in g t h ru st ( a r ). m o n : m o n te llo c o n g lo m e ra te ; o s p : o so p p o c o n g lo m e ra te ; b g m : b o rg o d i m e zz o s yn th e m ; v m i: v ia d i m o lin s yn th e m ; a o n : a o n e d is s y n th e m ; p l i: p la in o s y n th e m ; v l z : v il lu z z a s yn th e m ; s n m : s a n ta m a rg h e ri ta s yn th e m ; n d s : c a n o d u s s o s y n th e m . 1 -1 6 : e v o lu ti o n e p is o d e s o f e xa m in e d p la in ( fo r d e sc ri p tio n s e e c p t. 6 ). b ) d e ta il p ic tu re o f v ia d i m o lin s lo p e . a ) s e zi o n e s ch e m a tic a d e lla s e zi o n e d i s a n p ie tr o – a o n e d is ( b -b i in f ig . 1 , e sa g e ra zi o n e v e rt ic a le x 5 ), d a n o ta re i d if fe re n ti r ig e tt i ve rt ic a li ca u sa ti d a lla fa g li a i n c re s c it a a rb a -r a g o g n a ( a r ). m o n : c o n g lo m e ra to d e l m o n te llo ; o s p : c o n g lo m e ra to d i o so p p o ; b g m : s in te m a d i b o rg o d i m e zz o ; v m i: s in te m a d i v ia d i m o lin ; a o n : s in te m a d i a o n e d is ; p l i: s in te m a d i p la in o ; s in te m a d i v ill u zz a ; s n m : s in te m a d i s a n ta m a rg h e ri ta ; n d s : s in te m a d i c a n o d u ss o . 1 -1 6 : e p is o d i d e ll’ e vo lu zi o n e d e lla p ia n u ra i n e sa m e ( p e r la d e sc ri zi o n e v e d i ca p . 6 ). b ) f o to d e lla s ca rp a ta d i v ia d i m o lin . g. paiero & g. monegato m a .s .l. light reddish brown (5yr6/4) colored. stratification is tilted and has an average dip of 30 degrees southeastward. the basal boundary is characterised by an angular unconformity of 15 degrees with osoppo conglomerate strata. the top of unit is an erosion surface. this unit represents a buried early alluvial fan sequence of arzino stream. 55..22.. vviiaa ddii mmoolliinn ssyynntthheemm ((vvmmii)):: outcropping next to via di molin, this unit is made by crudely-bedded gravel (gh) normally consolidated and clast-supported; clasts are subrounded, carbonate, granule to coarse cobble sized. matrix is silty sand. massive (sm) to planar cross-beds (sp) sandy levels, about 2 m thick, are interbedded. lower boundary does not outcrop; upper boundary is given by a weathered surface, developed on the deposits of this unit, with an argillic horizon about 50 cm thick and strong brown (7.5yr5/6) colored (fig. 5). the unit represents an arzino stream alluvial deposit. 55..33.. aaoonneeddiiss ssyynntthheemm ((aaoonn)):: outcropping from pinzano narrow to aonedis, it is made by stratified sandy gravel (gt), clast-supported to partially open-work, with subangolar to subrounded carbonate clasts (more than 95% of white or gray carbonate), medium pebble to cobble sized; massive sandy levels (sm) are common and have an average thickness of 1 meter. next to these ones some discontinuous horizons, rich of organic matter, are joined; one of these (rome1428) was dated >>4433..000000 yr bp. the lower boundary is an erosion surface, that northernside of ponte brook is emphasized by an angular unconformity that reaches 30° with borgo di mezzo synthem’s strata; the upper boundary is an alluvial erosion surface. unit is 15÷20 m thick and represents an arzino stream alluvial deposit. 55..44.. ppllaaiinnoo ssyynntthheemm ((ppllii)): this unit, outcropping from borgo di mezzo terrace slopes to aonedis slope, is made by crudely bedded (gh) sandy gravels, clast-supported; with subrounded tagliamento's basin clasts (polychromatic carbonates, siliceous sandstones, volcanites and metamorphites), medium pebble to fine boulder sized. deposits of this unit are easily distinguishable from the bottom and top arzino basin's ones for polychromic clasts typical of tagliamento basin. moreover, as notified by feruglio (1929a), in borgo di mezzo terrace slopes a strongly weathered massive and matrix-supported diamicton, rich in striated clasts, is present. both boundaries are erosion surfaces. in villuzza slope of ponte brook valley upper boundary is made by a buried soil 3.2 m thick, with a 180 cm argillic reddish brown (5yr5/4) colored horizon; the soil is developed on the deposits of this unit. average thickness is of 5-7 m. these deposits represent the evidence of the older glacial expansion so far observed in san pietro aonedis section. according to their stratigraphic position they are probably related with glacial ones of rio ponte section and here credited to the same unit. 55..55.. vviilllluuzzzzaa ssyynntthheemm ((vvllzz)): outcropping from pinzano narrow to aonedis, this unit is made by crudely-bedded stratified gravel (gh) to stratified gravel (gt), clast-supported to partially open-work, with some interbedded lenses of massive silty sand (sm); carbonate clasts, fine pebble to cobble sized, point out an arzino basin alluvial deposit. both boundaries are erosion surfaces. villuzza synthem is 5÷10 m thick and represents last alluvial depositional event clearly ascribing to arzino stream. 55..66.. ssaannttaa mmaarrgghheerriittaa ssyynntthheemm ((ssnnmm)): outcropping from rio ponte valley to aonedis slope; this unit is made by clast-supported massive gravel (gcm) to crudely bedded gravel (gh) with sandy matrix; clasts are subrounded, pebble to cobble sized; deposit is normally consolidated and locally weakly cemented. petrography of clasts point out a tagliamento basin origin. boundaries are erosion surfaces; between them the lower is easily locating by petrographic composition of clasts. it has an average conserved thickness of 5 meters. these deposits represent the outwash plain of glacial event, whose glacial deposits were described in santa margherita synthem in rio ponte section. inside ponte and fos incisions physical relationship of these deposits with glacial ones is visible; in these outcrops, gravels are coarser next to glacial deposits. 191 fig. 5 paleosol at aonedis synthem lower boundary in via di molin slope. vmi: via di molin synthem; aon: aonedis synthem. paleosuolo in corrispondenza del limite inferiore del sintema di aonedis sulla scarpata di via di molin. vmi: sintema di via di molin; aon: sintema di aonedis. the pleistocene evolution of arzino ... 55..77.. ccaannoodduussssoo ssyynntthheemm ((nnddss)): this unit outcrops at the top of sequence from san pietro to aonedis; it is made by clast-supported massive gravel (gcm) to crudely bedded gravel (gh) with tagliamento's basin subrounded clasts, medium pebble to boulder sized, with silty-sandy matrix; deposits are normally consolidated. basal boundary is an erosion surface over every present units; upper boundary is the topographic surface marked by a soil having dark yellowish brown (10yr4/4) to brown (7.5yr4/4) color. thickness of this unit increases downstream from 10 to 20 meters. these deposits represent the sandur of last glacial advance and they are heteropic with glacial deposits observed in ponte brook site. 66.. ddiissccuussssiioonn aanndd ccoonncclluussiioonn stratigraphic units and discontinuities recognised during geologic survey, supported by some chronological data, allow to distinguish several depositional and erosion episodes, from which it is possible to go back to the pleistocene evolution of this area. tectonic influence on deposits architecture nowadays visible is not marginal; presence of arba-ragogna thrust (zanferrari et alii, in prep.), traceable next to ponte brook valley (fig. 1), contributed to determine the stratigraphic differences existing between the two slopes of the same valley. a certain dating of ancient units, because of lack of chronological data and tectonic deformation undergone, seems not possible; then a relative chronology is presented; reliability became better for late pleistocene units. sequence of deposits outcropping in left tagliamento slope and its tributaries’ ones is held between two main boundaries: the lower is the erosion surface on osoppo conglomerate, an angular unconformity on which pleistocene sedimentation of arzino alluvial fan began, this boudary can be combined with miall (1996) 8th-order type (episode 1 in fig. 4a); the upper is topographic surface relative to last glacial maximum event in tagliamento basin and the late pleistocene holocene incision (6th-order type). borgo di mezzo synthem represents an apex alluvial fan sequence of arzino stream (episode 2 in fig. 4a), a part of the dip of the strata has probably a tectonic origin (fig. 4a). alteration of deposits, general steepness and its stratigraphic position at the base of the pleistocenic sequence allow to give to this synthem an early-middle pleistocene age. the southern side of ragogna hill has been contemporary interested by early stage of small alluvial fans, according to the classification after blair & mcpherson (1994); these fans were characterised by colluvial slides, debris flows and incised channel flows sedimentary processes (rio ponte unit). afterwards the trenching of borgo di mezzo synthem’s alluvial fan (episode 3 in fig. 4a) an aggradation took place, witnessed by via di molin synthem; it likely represents a distal fan which partially backfilled the shaped valley (episode 4 in fig. 4a); afterwards its deposits were pedogenized during a sedimentary stasis (episode 5 in fig. 4a). then aonedis synthem was deposited (episode 6 in fig. 4a). the sedimentary facies suggests a fan apex located more upstream than borgo di mezzo one, with several sandy beds and more sorted clast average. aonedis synthem lower boundary, clearly diachronic, is an angular unconformity, as to borgo di mezzo deposits, concerning a 7th order bounding surface. whereas weathered surface, that emphasizes boundary with via di molin synthem, can be combine with a 6th order one. stratigraphic position, besides chronological data (>43.000 yr bp), gives to aonedis synthem a middle pleistocene age, when arzino stream was still free to growing up its fan downstream of pinzano narrow. in southern side of ragogna hill went on rio ponte unit deposition. then first documented local glacial advance took place, represented by plaino synthem (episode 8 in fig. 4a); its basal boundary is an erosion surface (episode 7 in fig. 4a) and it does not give any information about relationship with aonedis synthem deposits; consequently the rank of boundary becomes vague. the deep evolution of upper boundary's paleosol and the strong reshaping allow to give a middle pleistocene age to this glacial unit. at the same time rio ponte unit aggradiation was stopped and buried by this glacial event, afterwards evolution of these small brooks have been constrained inside incisions in glacial deposits. later on a likely trenching phase happened (episode 9 in fig. 4a), on the terraced surfaces the weathering growing on; arzino stream probably still flew down pinzano narrow. then the backfilling of arzino and its scattering over the plain (villuzza synthem) represent last documented arzino stream sedimentary event (episode 10 in fig. 4a) out of pinzano narrow (zanferrari et alii, in prep.). lower surface of this synthem, marked by a deep paleosol, can be credited to a 7th order boundary. afterwards santa margherita synthem represents the second local glacial event (episode 12 in fig. 4a) well documented in the whole tagliamento morainic amphitheatre, even though deposits’ morphology is strongly reshaped. its basal erosion surface (episode 11 in fig. 4a) gives unfit informations about the relationships with deposits of villuzza synthem; however these alluvial deposits lay in the same stratigraphic position, then a partial heteropy cannot be excluded. these two synthems can ascribed to middle-late pleistocene for their stratigraphic position. after this another entrenchment took place (episode 13 in fig. 4a), consequently a sedimentary stasis is documented, inside ponte valley, by a paleosol on glacial deposits of santa margherita synthem, that can be related to a 6th order bounding surface. then the last local glacial event (episode 14 in fig. 4a) covered deposits of the whole area (canodusso synthem). this depositional episode represents the last glacial maximum in tagliamento amphitheatre and here its age fits in 14c calibration range 23.040-22.240 (±1σ, yr bp) after stuiver et alii (1998). westerly, in tagliamento hydrographic right, the relevant sandur is made by deposits that are heteropic with alluvial fan deposits of meduna stream, whose 14c ages give the same time range (avigliano et alii, 2002). during final times of lower pleistocene and in the whole holocene, after glacial retreat, entrenchment of watercourses permits the formation of the high fluvial slopes (episode 15 in fig. 4a), located southward from pinzano narrow for about 18 km; thin holocene deposits 192 g. paiero & g. monegato are present inside mordaro, ponte and fos brooks valleys (episode 16 in fig. 4a). bbiibblliiooggrraapphhyy avigliano r., calderoni g., monegato g. & mozzi p. (2002) – the late pleistocene-holocene evolution of the cellina and meduna alluvial fans (friuli, ne italy). mem. soc. geol. it., 5577 (1): 133-139. baggio p., bellino l., carraro f., fioraso g., gianotti f. & giardino m. (1997) schede per il rilevamento geologico delle formazioni superficiali. il quaternario it. j. quat. sc., 1100 (2): 655-680. bini a. & orombelli g. (1988) – considerazioni sulla terminologia dei sedimenti glaciali. “natura bresciana” ann. mus. civ. sc. nat., brescia, 2244: 213-216. blair t.c. & mcpherson j.g. (1994) alluvial fans and their natural distinction from rivers based on morphology, hydraulic processes, sedimentary processes and facies assemblages. j. sed. res., aa6644: 450-489. blair t.c. & mcpherson j.g. (1999) grain-size and textural classification of coarse sedimentary particles. j. sed. res., 6699: 6-19. boyce j.i. & eyles n. (2000) architectural element analysis applied to glacial deposits: internal geometry of a late pleistocene till sheet, ontario, canada. gsa bull., 111122:: 98-118. carraro f. & petrucci f. (1977) geologia dei depositi superficiali: anfiteatro morenico. in: b. martinis (ed.): studio geologico dell’area maggiormente colpita dal terremoto friulano del 1976. riv. it. strat. paleont., 8822: 193-393, milano. carraro f. & petrucci f. (1982) tentative assessment of the deformation of a morainic amphitheatre: the tagliamento amphitheatre (italy). z. geomorph. n. f., 2266: 331-341. comel a. (1955) monografia sui terreni della pianura friulana. ii. genesi della pianura centrale connessa all’antico sistema fluvioglaciale del tagliamento. n. ann. ist. chim. agr. sperim. gorizia, 66: 1-216. comel a. (1956) monografia sui terreni della pianura friulana. iii. genesi della pianura occidentale costruita dal meduna, dal cellina e da corsi d'acqua minori. n. ann. ist. chim. agr. sperim. gorizia, 77: 5-93. croce d. & vaia f. (1985) aspetti geomorfologici dell'anfiteatro tilaventino (friuli). gortania-atti. mus. friulano st. nat., 77: 5-36. dalla vecchia f.m. & rustioni m. (1996) mammalian trackways in the conglomerato di osoppo (udine, ne italy) and their contribution to its age determination. mem. sci. geol., 4488: 221-232, padova. di bernardo f., florean m. & vaia f. (1998) – i conoidi del tagliamento e del torre: aspetti evolutivi. gortania atti museo friul. storia nat., 2200: 23-39. eyles n., eyles c.h. & miall a.d. (1983) lithofacies types and vertical profile models; an alternative approach to the description and environmental interpretation of glacial diamict and diamictite sequences. sedimentology, 3300: 393-410. feruglio e. (1920) i terrazzi della pianura pedemorenica friulana. uff. idrogr. r. magistrato acque venezia, 107: 1-93. feruglio e. (1925) carta geologica delle tre venezie. foglio 25 udine. uff. idrogr. r. magistr. acque di venezia. venezia. feruglio e. (1929a) nuove ricerche sul quaternario del friuli. giorn. geol., s. 2, 4:1-36, bologna. feruglio e. (1929b) note illustrative della carta geologica delle tre venezie: foglio "udine". uff. idrogr. r. magistrato acque venezia, 77 pp., venezia. gortani m. (1959) carta della glaciazione würmiana in friuli. rend. atti. acc. sci., ist. bologna, s. 11, 66:1-11. issc – international stratigraphic subcommission on stratigraphic classification (1994) – international stratigraphic guide (isg). second edition, pp. 213. massari f., grandesso p., stefani c. & jobstraibizer p.g. (1986) a small polyhistory foreland basin evolving in a context of oblique convergence: the venetian basin (chattian to recent, southern alps, italy). in: allen p. & homewood p. (eds.) foreland basins. spec. public. int. ass. sediment., 8: 141-168, blackwell scientific publ., oxford. miall a.d.(1996) the geology of fluvial deposits. springer-verlag, berlin heidelberg. m.u.r.s.t. (1997) – carta altimetrica e dei movimenti verticali del suolo della pianura padana. 3 sheets, 1:250.000 scale; s.el.ca., firenze. penck a. & brückner e. (1909) die alpen im eiszeitalter. 3 vol., 1199 pp., tauchnitz, leipzig. sacco f. (1937) il glacialismo veneto. l'universo, 77: 1-40, firenze. stuiver m., reimer p.j., bard e., beck w.j.; burr g.s., hughen k.a., kromer b., mc cormac g., van der plicht j. & spurk m. (1998) "intcal98 radiocarbon age calibration, 24,000–0 cal bp" radiocarbon, 4400: 1041-1083. taramelli t. (1875) dei terreni morenici e alluvionali del friuli. ann. r. ist. tecn. udine, 88: 1-91. tellini a. (1892) descrizione geologica della tavoletta "majano". in alto, 33: 18-25, 44-48,76-81. zanferrari a., marchesini a., monegato g. & avigliano r. (2000) – il progetto carg-fvg: la nuova cartografia geologica nazionale nella regione friuli – venezia giulia. rass. tecn. del friuli venezia giulia, llii ((66)): 23-26. zanferrari a., poli m.e. & rogledi s. (2002) the external thrust-belt of the eastern southern alps in friuli (ne italy). mem. sci. geol., 5544: 159-162. zanferrari a., avigliano r., calderoni g., carraro f., grandesso p., marchesini a., monegato g., paiero g., poli m.e., ravazzi c. & stefani c. (in prep.) – note illustrative della carta geologica d’italia alla scala 1:50.000: foglio 065 “maniago”. servizio geologico d’italia – regione autonoma friuli – venezia giulia. zenari s. (1927) carta geologica delle tre venezie, foglio "maniago". uff. idrogr. r. magistrato acque venezia. 193 ms. ricevuto il 6 maggio 2003 testo definitivo ricevuto il 3 settembre 2003 ms. received: may 6, 2003 final text received: september 3, 2003 the pleistocene evolution of arzino ... imp.distefano& the holocene marine depositional event in the historical centre of palermo enrico di stefano, sergio bonomo & alessandro incarbona università degli studi di palermo dipartimento di geologia e geodesia corso tukory , 131 90134 palermo edist@unipa.it abstract: di stefano e., bonomo s., incarbona a., the holocene marine depositional event in the historical centre of palermo. (it issn 0394-3356, 2004). recent data have pointed out that, above the classical depositional sequence of the quaternary marine sediments of the palermo coastal plain, post-tyrrhenian sediments occur. in order to determine the age of these sediments and to confirm the deposition of a recent sedimentary cycle, microfossil assemblage of several samples, coming from geognostic drillings, have been analysed. using the calcareous nannofossil ecobiozone scheme recently proposed for the last deglaciation of the central mediterranean (sicily channel), examined sediments can be ascribed to the holocene. radiocarbon analysis confirmed such an attribution providing a more accurate stratigraphic determination. riassunto: di stefano e., bonomo s., incarbona a., the holocene marine depositional event in the historical centre of palermo. (it issn 0394-3356, 2004). studi recenti hanno indicato come al di sopra della classica sequenza del quaternario marino della piana di palermo ricorra, in alcuni siti del centro storico, un limitato spessore di depositi marini di età post-tirreniana. con lo scopo di precisare l’età di tali depositi sono state studiate le associazioni di microfossili di campioni provenienti da sondaggi geognostici. utilizzando lo schema ecobiozonale a nannofossili calcarei recentemente proposto per l’ultima deglaciazione nel mediterraneo centrale (canale di sicilia) detti depositi contengono nannoflore attribuibili all’olocene. un'analisi al radiocarbonio ha confermato tale attribuzione, limitando alla parte bassa dell'olocene la pertinenza stratigrafica di tali depositi. keywords: holocene, calcareous nannofossils, foraminifera, radiocarbon convention age, northern sicily. keywords: olocene, nannofossili calcarei, foraminiferi, età radiocarbonio, sicilia settentrionale. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 285-291 introduction since the last century, palermo’s coastal plain has been considered as a classical reference for marine quaternary studies. after doderlain (1872), several authors developed studies on pleistocene chronostratigraphy, biostratigraphy and palaeoclimatology, based on these marine sediments (de stefani 1891-2; gignoux 1913; emiliani et al. 1958; gradstein 1970; ruggieri & sprovieri 1977; di stefano & rio 1981; buccheri 1984). the central part of the coastal plain consists of a series of little plateau, moulded by marine action during the late quaternary. during the last glaciation (würm), they were isolated from each other for the deepening of two converging river-beds (kemonia fossil river and papireto fossil river). till historic age, when the town was confined within the “paleopoli” and the “neapoli”, the mouths of these two rivers flowed together in a deep inlet used as a seaport (fig. 1). then these rivers were hidden by human settlement, even though their course is also observable by the topographical and town-planning structure of the historical centre (fig. 2). several geognostic drillings were carried out during the last decades, to safeguard the main sites of monumental interest, contributing to improving the stratigraphic knowledge of the area (todaro 1995; giammarinaro et al. 2000). micropaleontological data based on calcareous nannofossils and foraminifera, coming from several core segments, will now be presented. geological framework m a r i n e q u a t e r n a r y s e d i m e n t s s e t t l e d i n palermo’s coastal plain can be ascribed to two main lithologies: silty-clays and/or calcarenites having a maximum thickness of about 80-100 metres. they cover the tectonic units of panormide carbonate platform and imerese basin, which are orogenetically deformed. these tectonic units are overlained by the oligo-miocene numidian flysch deposit (catalano et al. 1998). roughly, the calcarenitic facies lies on the siltyclays, except for the eastern part of the coastal plain, where the fossiliferous silty clays outcrop (acqua dei corsari and cava puleo – ficarazzi – sicilian stratotype) (fig. 3). these two litho-facies are part of a depositional sequence, chronostratigraphically spanning the upper part of the emilian, the entire sicilian and the lowermost part of the medium pleistocene (di stefano & rio 1981; catalano et al. 1998). recent micropaleontological data pointed out, for the first time, that the classical sequence just described is overlained by post-tyrrhenian marine sediments (di stefano 1998a). the aim of the present note is to specify the age of post-tyrrhenian marine sediments, making use of a recent calcareous nannofossil ecobiozonation (sprovieri et al. 2003) and of a 14c radiocarbon dating. 286 e. di stefano, s. bonomo & a. incarbona materials and methods analysed material comes from two cores (indicated as cores 1 and 2 in fig. 2). core 1 was recovered in the northern part of a depression, known as “conca del papireto”, bordering a promontory of sicilian calcarenites where the paleopoli (vii-viii century b.c.) was founded. the studied materials were sampled at -16 and -4 metres from the roadway. the second drilling is located in a street (via dei candelai) whose line coincides with the last part of the papireto bed-river, reclaimed in the xvi century. the studied samples were collected at -22 and -16 metres from the roadway. the calcareous nannofossil assemblages were studied following the standard procedure on the smear slide preparations and without performing any process that could affect the natural status of the sediment. quantitative analyses were conducted using a polarized microscope (transmitted light and crossed nicols) at about 1000 x magnification. the occurrence of emiliania huxleyi was checked by scanning electron microscope (sem) observations. fig 1 satellite photo of palermo. in white the traces of kemonia and papireto fossil river-beds. arrow points out the location of the “paleopoli neapoli” (modified from la duca 1999). fig 2 city plan of the historical centre of palermo and location of the geognostic drillings. in grey the track of the fossil river-beds hidden by human settlement. the foraminifera study was performed washing about 25 cc of dried sediments with a 63 µm sieve. to evaluate the absolute age (14c method) of the post-tyrrhenian fossiliferous clay level of “conca del papireto”, about thirty specimens of epiphyte benthic foraminifera (cibicides lobatulus, elphidium crispum, rosalina sp.) were picked. the selected specimens were perfectly preserved and at a different ontogenetic development degree. the analysis was performed at the center for accelerator mass spectrometry of lawrence (livermore national laboratory). results conca del papireto examined samples are representative of two lithologic levels located at -16 and -4 metres. they are respectively grey sandy-clays with fossils and vegetable remains and blue clays with small molluscs, echinoderm remains and vegetable carbonaceous remains. calcareous nannofossils: (-16 metres sample) examined sample indicated the total absence of autochtonous nannofloras. only very rare specimens of reworked paleogenic taxa, coming from the numidian flysch deposit, were observed. (-4 metres sample) the calcareous nannofossil assemblage is scarcely diversified but rich in specimens, characterized by the dominance of e. huxleyi (fig. 4a). quantitative analyses, by countings on the first 300 specimens, pointed out that this taxon occurs with abundance values exceeding 45%. common specimens of gephyrocapsa oceanica (fig. 4b) and rare ones of small gephyrocapsa and braarudosphaera bigelowii were also detected. genus helicosphaera occurs with common helicoliths belonging to three different species. on the basis of the above compositional and quantitative data, the assemblage was ascribed to the mnn21b biozone (rio et al. 1990). moreover, quite a shallow marine environment with a temperate climate can be supposed. a slightly lowered salinity can be invoked on the basis of the occurrence of b. bigelowii that has been often reported as a species of coastal environment and/or low salinity (bukry 1971; müller 1979). again specimens of reworked paleogenic taxa (sphenolithus conicus and sphenolithus sp.) occur. 287the holocene marine depositional ... the following taxa were recognized: braarudosphaera bigelowii calcidiscus leptoporus emiliania huxleyi gephyrocapsa oceanica small gephyrocapsa helicosphaera hyalina helicosphaera carteri helicosphaera wallichii foraminifera: (-16 metres sample) only few species and specimens of coastal benthic foraminifera were observed, representative of a very reduced bathyfig 3 simplified geologic map of palermo's coastal plain and schematic stratigraphic columns (modified from abate b. et al. 1982). fig 4 a emiliania huxleyi (sem). b gephyrocapsa oceanica (mop, x nicols). 288 metry. among them ammonia beccarii, elphidium crispum and rare miliolids. (-4 metres sample) a diversified assemblage, with well preserved specimens at different ontogenetic levels, were observed. benthic foraminifera are very abundant, characterized by the dominance of epiphyte taxa: planorbulina mediterranensis, rosalina sp., cibicides lobatulus together with a. beccarii, e. crispum and miliolids. this assemblage testifies an evolution in the depositional environment towards deeper conditions (several tens of metres). such a consideration is in agreement to the occurrence of very few specimens of planktonic foraminifera: globigerina bulloides and globorotalia inflata. via dei candelai examined samples are representative of two sedimentary levels located at -22 and -16 metres. they are respectively representative of fossiliferous grey sandyclays and dark silty-clays with small molluscs. calcareous nannofossils: (-22 metres sample) the nannofloral assemblage is not well diversified with over 45% of small placoliths of e. huxleyi. g. oceanica and b. bigelowii are also significantly present. on these basis the assemblage might be again considered as indicative of the biozone mnn21b and belonging to a stratigraphic level correlatable with the considered higher sample of “conca del papireto”. (-16 metres sample) furthermore, the calcareous nannofossil assemblage resulted less diversified, almost entirely constituted by small placoliths of e. huxleyi and representative of the biozone mnn21b. stratigraphy in the two investigated sites, calcareous nannofossil assemblages pertaining to the biozone mnn21b were detected. such data can be considered as an innovation relative to the known stratigraphic framework. firstly, the younger marine sediments which settled in the coastal plain were ascribed to the blue clays and/or to the calcarenites that are in transgression on the oligo-miocene deposits (numidian flysch). both litofacies belong to a sedimentary cycle begun with the marine transgression of the emilian substage and they are bounded in the upper part by a erosive surface that is surely more recent than the marine isotopic stage (mis) 22 (di stefano & rio 1981; buccheri 1984; di stefano 1998b). the first mention of the existence of more recent marine sediments, although with a relatively little thickness, is linked to the detection of e. huxleyi acme in sediments referable to the mnn21b biozone (di stefano 1998a). this biozone covers the uppermost part of the latest pleistocene and holocene. using recent biochronologic data, mainly obtained by sediments recovered during the cruise of the ocean drilling program (odp leg 160), e. huxleyi's increase in abundance always occurs above mis 5 and sapropel s3 in the mediterranean sea (castradori 1993; sanvoisin et al. 1993; flores et al. 1997; di stefano 1998b; sprovieri et al. 1998; de kanel et al. 1999). therefore these sediments are an insight that a post-tyrrhenian sea re-entrance occurred, at least in the central sector of palermo’s coastal plain. quantitative abundance data on the calcareous nannofossil assemblages of the uppermost late pleistocene-holocene and the recently proposed ecobiozonation of the last ca. 20 kyrs in the sicily channel (odp-site 963) strongly enhanced the stratigraphic resolution of the upper part of the biozone mnn21b. on these basis, the above mentioned transgression of sea water on the coastal plain can be restricted to the holocene. infact, the occurrence of several specimens of g. oceanica, is compatible only with ecozones 3n, 2n and 1n (sprovieri et al. 2003). this taxon marks a re-entrance event just above the base of the holocene (di stefano & incarbona 2004) (fig. 5) after an interval of virtual absence that covers the entire würm (di stefano & incarbona unpublished data). age dating in order to reach a more accurate age determination of the above mentioned depositional event, a 14c radiocarbon analysis was performed. about thirty specimens of epiphyte benthic foraminifera (c. lobatulus, e. crispum and rosalina sp.) at a different ontogenetic development were selected. the obtained result was 7780 ± 60 b.p. (radiocarbon convention age) (tab. 1). fig 5 quantitative distribution pattern of gephyrocapsa oceanica in the sedimentary record of odp hole-963d compared with calcareous nannofossil ecozones, with the stages of the event stratigraphy and with the stratigraphic subdivision of mangerud et al. 1974. on the right the available age control based on three age determinations (radiocarbon convention age) is reported (modified from di stefano & incarbona 2004). e. di stefano, s. bonomo & a. incarbona 289 so the sediments can be referred to the lower part of the holocene during the last phase of the deglaciation, while the sea-level was reaching the maximum highstand (bjørck et al. 1998). such an age is nearly correspondent to that obtained in the middle part of the ecozone 2n (7510 ± 60 b.p. radiocarbon convention age) of sprovieri et al. (2003) (fig. 5). discussion the marine sedimentation established at least in the central sector of palermo’s coastal plain at about 7.8 kyrs b.p. (radiocarbon convention age), provides remarkable indications on the possible depositional history of this coastal region. recent palaeoclimatic studies outlined the sequence of the most important fluctuations in the climatic system during the last deglaciation, mainly on the basis of the isotopic record of greenland ice cores (chappelaz et al. 1990; alley et al. 1993; bond et al. 1993; grootes et al. 1993). a significant warming event marked the end of the younger dryas (gs-1) (fig. 6) and characterized the lower part of the holocene. as a consequence a fast sea level raising has been reported on the eustatic curves. the raising of the sea level was evaluated in about 120 metres in coincidence of the deglaciation culmination (fairbanks, 1989). the radiometric age obtained for “conca del papireto” sample, links the deposition of holocene palermo’s coastal plain sediments to the deglaciation culmination event. sea waters flowed on the coastal sectors of the plain using as a preferential way the fossil river-beds of kemonia and papireto, lowered during the glacial würm period. further samples, coming from small segments of cores of the historical centre, with nannofloras again referable to the holocene has been recently recovered, demonfig 6 δ18o profile from greenland ice core gisp2, compared with the classical sequence of events related to the last deglaciation (mangerud et al. 1974). tab. 1 report on 14c radiocarbon analysis, performed on the papireto sample the holocene marine depositional ... 290 strating that the sea re-entrance interested several places and had therefore a significant extension (fig. 2). the collected foraminiferal data infers that during this sea water re-entrance, a water column estimated in several tens of metres existed on the sea floor in the papireto site. conclusions micropaleontological analyses based on calcareous nannofossils and foraminifera were carried out on some samples of the historical centre of palermo, selected as possible indicators of a post-tyrrhenian depositional sequence. samples within the papireto fossil river-beds are characterized by the dominance of e. huxleyi together with the occurrence of several specimens of g. oceanica. they are compatible with holocene nannofossil ecozones. moreover, faunistic and floristic assemblages point out a shallow water marine environment and a temperate climate. an age determination was performed and the result was 7780 ± 60 yrs bp (radiocarbon convention age). it confirms that, in this area, marine sediments were deposited during the lower part of the holocene. this age is indicative of the last phase of the deglaciation and is almost coincident with the maximum high-stand of the sea level. we suggest that the sea water flowed on the coastal plain of the historical centre of palermo using as a preferential way the kemonia and papireto fossil riverbeds, deeply eroded during the würm glacial period. acknowledgments studied samples were provided by “studio diagnostico del centro storico della città di palermo” and miur project, coordinators r. catalano and m. s. giammarinaro. we are thankful to them and to their coworkers. thanks are also due to sicilsonde s.n.c. for providing the sample of “conca del papireto”. this research has been supported by miur ex 60% grants to e. di stefano. references abate b., catalano r. & renda p. 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(2003) high-resolution record of the last deglaciation in the sicily channel based on foraminifera and calcareous nannofossil quantitative distribution. palaeogeogr., palaeoclimatol., palaeoecol., 202: 119-142. sprovieri r., di stefano e., howell m., sakamoto t., di stefano a. & marino m., (1998) integrated calcareous plankton biostratigraphy and ciclostratigraphy at site 964. in emeis k.c., robertson a.h.f., richter c. & camerlenghi a. (eds), proc. odp, scient. res., 160. todaro p. (1995) palermo: geologia del centro storico. atlante geologico-stratigrafico. dario flaccovio editore, 119 pp. 291 ms. ricevuto il 21 maggio 2004 testo definitivo ricevuto il 28 settembre 2004 ms. received: may 21, 2004 final text received: september 28, 2004 the holocene marine depositional ... imp.sauro-zampieri eevviiddeennzzee mmoorrffoollooggiicchhee ddii tteettttoonniiccaa rreecceennttee ssuull mmaarrggiinnee oorriieennttaallee ddeellllaa mmaaiieellllaa ((aappppeennnniinnoo cceennttrraallee)) uuggoo ssaauurroo11 && ddaarriioo zzaammppiieerrii22 1dipartimento di geografia dell’università di padova, e-mail: ugo.sauro@unipd.it 2dipartimento di geologia, paleontologia e geofisica dell’università di padova, e-mail: dario.zampieri@unipd.it riassunto: sauro u. & zampieri d., evidenze morfologiche di tettonica recente sul margine orientale della maiella (appennino centrale). (it issn 0394 – 3356, 2004). la montagna della maiella è una delle massime elevazioni dell’appennino centrale e la sua grande scarpata orientale è una delle forme tettoniche più spettacolari di tutta la catena. la scarpata è modellata sul fianco di una piega anticlinale, espressione di una sottostante faglia inversa facente parte del sistema neogenico di sovrascorrimenti a vergenza adriatica. l’alto strutturale della maiella deriva tuttavia in parte anche dalla fisiografia dell’avanfossa, in quanto prima della fase di raccorciamento era un horst delimitato da faglie normali antitetiche. in prossimità dello sbocco a valle del grandioso canyon del vallone di s. spirito che incide la maiella, esiste un fenomeno di sbarramento interpretabile come la conseguenza dell’espulsione verticale di un cuneo tettonico in prossimità della base della scarpata. in relazione ai caratteri della stretta forra che ha inciso lateralmente la "diga in roccia", è possibile ipotizzare che l’evento tettonico che ha determinato l’espulsione del cuneo sia riferibile a un momento relativamente recente, anche se difficile da definire con precisione, del pleistocene. pertanto la morfostruttura della maiella non avrebbe cessato la sua attività nel pliocene superiore, come sostenuto dalla letteratura geologica, ma sarebbe stata attiva anche nel quaternario. abstract: sauro u. & zampieri d., geomorphological evidences of recent tectonics along the eastern side of the maiella massif (central apennines). (it issn 0394 – 3356, 2004). the maiella mountain is one of the highest elevations of the central apennines. its huge eastern scarp is also one of the most spectacular tectonic landforms of the belt. the escarpment represents the forelimb of a thrust-related anticline belonging to the neogene adriatic-verging thrust system. nevertheless, the maiella structural high partly results from the shortening of a pre-orogenic horst bounded by antithetic normal faults. in the lower segment of the vallone di s. spirito, one of the main canyons which cuts in the scarp, it is possible to recognize a damming event caused by the extrusion of a tectonic wedge. on the base of the characters of the narrow gorge engraved in the natural dam, the related tectonic episode is referable to a relatively recent moment, even if not easy to be precisely defined, of the pleistocene. thus, it is possible to infer that the maiella morphostructure has not ceased its activity in the upper pliocene, as reported in the geological literature, but has been active also during the quaternary. parole chiave: tettonica recente, erosione fluviale, geositi, appennino centrale. keywords: recent tectonics, fluvial erosion, geosites, central apennine il quaternario italian journal of quaternary sciences 1177(1), 2004, 3-9 11.. pprreemmeessssaa la scarpata che costituisce il margine orientale del massiccio della maiella è una delle più spettacolari forme tettoniche dell’appennino. tale scarpata, che presenta in pianta una forma arcuata, convessa verso est per una lunghezza di oltre 30 km, raccorda le dorsali e gli altopiani sommitali della maiella, che si estendono al di sopra dei 2000 m s.l.m., con la fascia di colline che degrada gradualmente verso la costa adriatica. la transizione morfologica fra la scarpata ed il rilievo collinare ha luogo lungo una linea che corre oscillando fra le quote di 400 ed 800 metri, è molto netta e caratterizzata da un cambiamento sia del tipo di rocce, sia dello stile topografico. infatti, tale linea marca il contatto tra i calcari di piattaforma di scarpata/bacino cretaceo-miocenici e i sedimenti evaporitici e torbiditici silicoclastici miopliocenici (crescenti et al., 1969; vecsei et al., 1998; vezzani & ghisetti, 1998). sulla scarpata, ove affiorano estesamente i calcari di piattaforma, si osserva un incremento delle pendenze da monte verso valle, tale da dare l’impressione di trovarsi di fronte ad una forma tettonica particolarmente giovane, ancora attiva. un problema dello studio di questo tipo di grandi scarpate tettoniche connesse a sistemi di faglie di tipo inverso, e quindi a deformazioni di tipo compressivo, è, tuttavia, quello che, a differenza delle scarpate di faglia normale, non vi si trovano facilmente fenomeni di "surface faulting" tali da permettere di individuare episodi recenti di riattivazione della struttura. e’ quindi indispensabile analizzare queste scarpate in tutte le loro caratteristiche morfologiche per tentare di individuarvi altri tipi di indizi di movimenti tettonici recenti. da questo punto di vista una delle aree più interessanti e complesse di questa grande scarpata è il segmento intermedio, caratterizzato da un complesso sistema di profonde incisioni del tipo canyon fluviocarsico che seguono prevalentemente le direzioni di massima inclinazione degli strati (valli cataclinali di tipo conseguente), ma che si sono impostate in sistemi di fratturazione connessi, almeno in parte, con le 4 u. sauro & d. zampieri condizioni di rilascio tensionale innescate dall’evoluzione morfotettonica della stessa scarpata. in questo lavoro viene presentato un aspetto presente proprio nel contesto di una di queste incisioni, che, secondo noi, è più che un indizio di una riattivazione recente di strutture preesistenti, riconducibile, a grandi linee, ad un momento relativamente recente, anche se di non facile definizione, del pleistocene. 22.. iinnqquuaaddrraammeennttoo ssttrruuttttuurraallee l’anticlinale della maiella rappresenta la struttura affiorante più esterna del sistema di sovrascorrimenti dell’appennino centrale, sviluppatosi a partire dal miocene inferiore (casnedi et al., 1981; ghisetti & vezzani, 1983, 1997). in pianta l’anticlinale presenta una forma arcuata con la concavità rivolta ad ovest e l’asse immergente a nord, dove la struttura è ricoperta in discordanza dai depositi del pliocene superiore. in sezione ha una forma asimmetrica con il fianco orientale (esterno) più ripido. sul lato occidentale (interno) è interessata da un sistema di faglie normali postcollisionali immergenti a ovest, di cui quella del monte morrone è tuttora attiva e viene interpretata come collasso gravitazionale del settore appenninico più ispessito e sollevato (ghisetti & vezzani, 1999a), oppure come migrazione dell’apertura del bacino tirrenico (e.g. lavecchia et al., 1994). faglie normali sinsedimentarie messiniane-plioceniche delimitano il fianco interno (faglia di caramanico), ma anche il fianco esterno dell’anticlinale della maiella (scisciani et al., 2000). queste ultime erano in origine immergenti verso l’avanfossa e durante lo sviluppo dell’anticlinale connesso al raccorciamento sono state ruotate ad assumere l’attuale immersione verso ovest ed un’apparente geometria da faglie inverse. l’alto strutturale della maiella sarebbe pertanto in parte derivato dalla fisiografia dell’avanfossa pliocenica inferiore (scisciani et al., 2002). i sedimenti di avanfossa silicoclastici del pliocene inferiore sono coinvolti nella deformazione compressiva e l’età del sovrascorrimento della maiella viene riferita essenzialmente al pliocene medio-superiore (ambrosetti et alii, 1983, casnedi et al., 1981, ghisetti & vezzani, 1983, 1997; scisciani et al., 2000, 2002), non essendo state riconosciute evidenze di un’attività quaternaria. il contatto tra i carbonati del fianco della maiella e i sedimenti terrigeni affioranti ad est di fara s. martino si presenta verticalizzato. per ghisetti & vezzani (1999b) tale assetto, accompagnato da locali movimenti normali e trascorrenti, sarebbe stato prodotto dall’attività tardo-pliocenica della linea volturno-sangro, una discontinuità profonda ad alto angolo con orientazione generale n-s e cinematica trascorrente destra, che corre lungo il fianco est della maiella. secondo cello et al. (1997) e tondi & cello (2003) il campo di stress tardo-quaternario dell’appennino centrale è caratterizzato da un regime trascorrente con asse principale massimo orizzontale orientato nw-se. 33.. eevvoolluuzziioonnee ggeeoommoorrffoollooggiiccaa il demangeot (1965) nella sua celebre memoria sulla geomorfologia degli abruzzi adriatici affronta in modo organico il problema dell’evoluzione geomorfologica del grande versante orientale di questo massiccio carbonatico e dei grandi canyon che lo incidono. sottolinea la freschezza della spettacolare scarpata tettonica, che sembra contrastare con l’età relativamente antica della faglia che la delimita a valle. nell’ambito del grande versante, egli indica diversi ordini di ripiani, che interpreta come spianate in roccia, relitti di antiche piattaforme di spianamento erosivo create in prossimità del livello di base (antico livello del mare) ad opera di fiumi costieri o dello stesso mare. sostiene di riconoscere nell’ambito dei profili longitudinali dei canyon un’alternanza di tratti relativamente poco inclinati rispetto alla pendenza media, correlabili sia tra di loro, sia con i ripiani dei versanti e distinguibili in un numero di ordini variabile tra due e quattro. per questo motivo interpreta i grandi canyon come delle forme policicliche, risultanti da un’alternanza di momenti di rapido sollevamento con momenti di stasi del sollevamento tettonico. conseguenza dell’evoluzione ciclica sarebbe anche il progressivo restringimento delle incisioni a partire dalla dorsale sommitale verso la periferia. il più alto degli ordini di ripiani sarebbe riferibile al tardo oligocene, mentre il più basso alla fine del pliocene (villafranchiano). in altre parole, la maiella si sarebbe andata sollevando e strutturando nell’arco di oltre 30 milioni di anni e l’ultima fase di attività tettonica importante sarebbe riferibile alla fine del pliocene o all’inizio del quaternario. se da un lato appare abbastanza ovvio che il sollevamento della maiella e la genesi della grande scarpata orientale siano il risultato di più episodi e fasi tettoniche ed è probabile che almeno alcuni dei ripiani di versante individuati dal demangeot siano relitti di superfici spianate in prossimità di antichi livelli di base, tuttavia, un’analisi dettagliata del quadro geomorfologico non fornisce elementi convincenti a favore delle conclusioni cui è giunto questo studioso. infatti, nell’ambito della grande scarpata alcuni ripiani in roccia si riconoscono, con una certa difficoltà, soltanto nel settore settentrionale, e l’analisi dei profili longitudinali dei canyon non consente di rilevare degli ordini di segmenti a bassa pendenza correlabili tra di loro (fig. 1). pertanto, il quadro geomorfologico d’insieme farebbe propendere per un sollevamento relativamente continuo, almeno in una dimensione geologica, piuttosto che per uno a scatti. le variazioni di pendenza dei profili dei canyon sembrano maggiormente legate a fattori locali di diverso tipo, piuttosto che ad un’evoluzione di tipo policiclico. da un’analisi geomorfologica, i canyon della maiella risultano essere forme complesse, risultanti da una cooperazione di processi di tipo diverso che si sono esplicati nel corso del sollevamento della montagna. e’ quindi corretto definirli canyon poligenetici piuttosto che canyon policiclici. ma si tratta certamente anche di forme relativamente giovani che non sembrano avere alle spalle una storia lunga come quella presupposta nel modello del demangeot. 44.. lloo ""ssbbaarrrraammeennttoo"" ddii vvaallllee ddeell vvaalllloonnee ddii ssaannttoo ssppiirriittoo chi si inoltri nello sbocco del vallone di s. spirito nel grande versante orientale della maiella (versante 5evidenze di movimenti tettonici ... adriatico) poco a monte di fara di san martino ha l’impressione, dopo aver percorso un centinaio di metri, di trovarsi chiuso il cammino da una parete in roccia (figg. 2, 3). solo l’osservazione attenta permette di scoprire sul lato sinistro della parete la stretta apertura di una forra che per 50 metri mantiene la larghezza di circa 2-3 m e che poi si apre, all’improvviso, in una forra molto più ampia (20-50 m) (fig. 4). questo stretto accesso alla forra interna ha determinato nel medioevo la scelta di costruire il monastero benedettino di s. martino, subito a monte dello sbarramento. era infatti facile impedire l’accesso ad eventuali predoni. il toponimo "vallone di s. spirito" è legato alla storia del monastero, poi abbandonato in seguito ad uno o più eventi di piena torrentizia, che ne hanno provocato un parziale seppellimento. l’improvviso restringimento della valle riguarda il tratto terminale del sistema idrografico val cannella vallone di macchia lunga vallone di s. spirito che costituisce una delle più spettacolari valli incassate nel grande versante orientale della maiella. su questo versante si scende dai 2793 m del m. amaro ai 400 m di fara di san martino su una distanza planimetrica di 10 km con una pendenza media di circa il 24%. tuttavia, nella fascia inferiore del versante le pendenze sono considerevolmente maggiori: mediamente quasi il 40% tra il m. acquaviva (2737) e fara di s. martino, circa il 45% tra il m. pizzone (2214) e fara di san martino, circa il 66% nella fascia di scarpata compresa fra 800 e 1800 m s.l.m., 4 km a sud di fara. il sistema idrografico inizia con un ampio circo glaciale per continuare con un vallone dapprima ad u, poi progressivamente a v e quindi con un canyon fluviocarsico sul cui fondo si individua una forra dalle pareti subverticali larga parecchie decine di metri ed a tratti ingombra di accumuli di frana e di grandi coni secchi di debris flow che determinano fenomeni di sbarramento ed alternanza di segmenti poco ripidi e di gradini. in sinistra idrografica il vallone di macchia lunga riceve la confluenza della valle delle mandrelle, la quale nasce da un circo a sud del m. acquaviva e risulta sospesa rispetto alla valle principale per la presenza di una gradinata di spettacolari salti. in destra idrografica, a se di cima dell’altare c’è un grande circo sospeso sul vallone di macchia lunga. nel segmento più a monte, la linea di fondovalle presenta la direzione wnw-ese, per poi tendere, nel tratto intermedio, ad una direzione w-e e quindi, nel segmento più a valle, ad un orientamento sw-ne, obliquo rispetto alla grande scarpata tettonica che qui caratterizza il bordo orientale della maiella. la forma del bacino idrografico è grossomodo quella dell’impronta di un fagiolo, più stretta alla sua estremità meridionale e della superficie complessiva di circa 26 km2. nella parte più a valle della forra, il profilo è spesso asimmetrico, in fig. 2 lo sbarramento roccioso del vallone di santo spirito visto da valle. una stretta forra sul lato sinistro permette di superare questa barriera. the natural rocky barrier of the canyon of santo spirito as seen from downvalley. a narrow gorge on the left side allows to bypass this obstacle. fig. 1 schizzo morfotettonico della maiella e profili longitudinali dei principali valloni che ne incidono il versante orientale. morphotectonic sketch of maiella mountain group and longitudinal profiles of the main canyons of its eastern slope. 6 quanto sul versante sinistro si alternano superfici di stratificazione, data la giacitura a franapoggio degli strati, con pareti; il versante destro è invece una grande parete interrotta soltanto da alcuni ripidi canaloni. in questa parte, l’andamento della forra risulta condizionato dalla giacitura degli strati, che diventano sempre più inclinati man mano che ci si avvicina alla scarpata periferica. l’incisione tende quindi ad assumere il carattere di valle omoclinale. la "diga" in roccia che costituisce lo sbarramento ha la forma di un cuneo più largo sul lato settentrionale e più stretto sul lato meridionale (rispettivamente circa 70 e 45 m). la sua superficie superiore è inclinata verso sud e pertanto l’altezza dello sbarramento decresce da nord verso sud (fra circa 40 e 20 m). la parete che guarda verso monte è obliqua rispetto all’asse della forra principale; la parete a valle è invece quasi ortogonale. lo spigolo superiore della parete a valle è arrotondato e pertanto il profilo è convesso, con un’accentuazione dove la parete è più bassa. qui la roccia appare molto più fessurata e fratturata che nella fascia inferiore. in basso la parete appare arretrata di pochi metri (1-5 m) rispetto al piano tettonico sezionato dal fianco destro della valle. la parete a monte mostra un arretramento più modesto rispetto al piano tettonico, dell’ordine del metro; risulta inoltre degradata da incavi e fessure da carsismo di contatto che raggiungono la profondità di circa 1 metro. la stretta forra che costituisce il bypass è una tipica forma di erosione torrentizia. presenta un asse inclinato di circa 70% verso sud, cioè verso la base del versante destro (meridionale). le pareti mostrano incavi e marmitte di parete, espressioni dell’elevata energia del corso d’acqua che ha percorso questa incisione trasportandovi ciottoli e massi. 55.. aassppeettttii ee ccoonnsseegguueennzzee ddii uunn eevveennttoo tteettttoonniiccoo rreecceennttee la "diga" in roccia che sbarra il vallone di s. spirito non può essere spiegata sulla base di semplici fenomeni di modellamento del rilievo ad opera di processi dell’erosione. certamente non si tratta di una contropendenza originata dall’erosione glaciale. a queste quote non esistono indizi di alcun tipo di modellamento glaciale. la congruenza tra questa forma ed i piani di faglia che la delimitano e che proseguono nelle pareti laterali (fig. 5) permette di ipotizzare che si tratti di una forma tettonica risultante dall’espulsione verticale di un cuneo tettonico in concomitanza con una riattivazione di strutture connesse con il sistema tettonico della grande scarpata orientale della maiella. e’ verosimile che un campo di stress attuale con asse principale massimo orizzontale orientato nw-se (cello et al., 1997, tondi & cello, fig. 3 lo sbarramento roccioso del vallone di santo spirito visto da monte. si intravede la stretta forra di incisione torrentizia sul lato destro. the natural rocky barrier of the canyon of santo spirito as seen from up-valley. the narrow gorge cut by a creek is on the right side. fig. 4 pianta della forra con i principali elementi strutturali. plan view of the gorge with the main structural elements u. sauro & d. zampieri 7 2003) possa produrre una transpressione sinistra su una struttura siffatta. non è tuttavia ancora del tutto chiaro il meccanismo cinematico in grado di produrre un movimento essenzialmente verticale di un cuneo che in sezione appare divergente verso il basso. alternativamente, nel caso il cuneo descritto fosse compatibile con il modello di deformazione del margine orientale della maiella descritto da ghisetti & vezzani (1999b), la linea volturno-sangro avrebbe continuato la sua attività anche nel pleistocene. sulla base dei diversi elementi raccolti è possibile abbozzare il seguente modello di evoluzione morfotettonica (fig. 6): a) in un momento geologico recente, eventi tettonici ravvicinati di riattivazione delle strutture connesse con la grande scarpata causano l’espulsione di un cuneo per un rigetto morfologico verticale superiore ai 20 metri; la parte superiore di questo cuneo presenta già un sistema di fessure precedentemente allargate dal fenomeno carsico, quando la roccia si trovava coperta dai riempimenti alluvionali del fondovalle; b) in seguito allo sbarramento della valle si forma una conca chiusa che potrebbe aver ospitato un lago effimero per le perdite di tipo carsico; c) il torrente riempie di depositi ciottolosi la depressione che si è creata a monte sino a colmarla; l’acqua presente nell’acquifero ospitato in questi depositi favorisce la carsificazione della parete sepolta; d) il torrente inizia ad incidere la soglia della diga in roccia; l’azione di incisione diventa efficace dopo che la depressione è stata colmata di depositi ciottolosi. nei momenti di piena si formano una corrente ed una cascata di acqua che trascinano ciottoli e che quindi esercitano una notevole capacità abrasiva; e) nei momenti di piena, la cascata determina uno smussamento dello spigolo a valle della "diga" ed un arretramento della parete, a cui si accompagna un’azione di incisione sul lato più basso della "diga", cioè sul suo margine meridionale, con conseguente formazione della stretta forra nella cui genesi gioca un ruolo importante l’azione di evorsione esercitata dai ciottoli trasportati. e’ possibile formulare anche altri modelli che, per esempio, prevedano un ripetersi degli episodi di deposizione a monte della "diga", con riempimento e ostruzione della forra in formazione, o, addirittura, seppellimento dell’intera "diga" in relazione all’alternarsi di fasi di maggiore o minore attività idrica del torrente e di produzione fig. 5 schizzo delle strutture tettoniche riconoscibili sulle pareti della forra principale appena a valle dello sbarramento. sketch of the main tectonic structures on the sides of the main canyon just downstream of the natural dam. fig. 6 schizzo della possibile evoluzione del fenomeno di sbarramento e di incisione della stretta forra. 1: situazione di pre-sbarramento, 2: espulsione tettonica e sbarramento, 3: incisione della forra. e’ necessario considerare che l’espulsione del cuneo ha comportato l’attivazione di più faglie sui due lati dello stesso con movimenti sia obliqui, sia verticali. sketch of the possible evolution of of the tectonic damming and of the down-cutting of the gorge. 1: pre-damming situation, 2: wedge expulsion and valley damming, 3: gorge cutting. it must be considered that the wedge expulsion interested different faults on both sides of the morphostructure with both oblique and vertical movements. evidenze di movimenti tettonici ... 8 di detrito nel bacino a monte. dal punto di vista dell’età di questa forma, se si tiene conto della larghezza e profondità della forra e dell’arretramento subito per erosione meccanica e per degradazione fisica e chimica dalle pareti della diga, si può ragionevolmente supporre si tratti di una forma che ha attraversato almeno una fase di intensa attività torrentizia, molto maggiore rispetto a quella attuale. nelle alpi, forre simili in ambienti glacializzati sono comunemente ritenute forme polifasiche, che si sono evolute nel corso di più oscillazioni glaciali (castiglioni, 1958). forme di queste dimensioni in val di non sono state però attribuite all’ultima glaciazione, sulla base di considerazioni sia morfologiche che di correlazione con i depositi glaciali (sauro, 1976). tuttavia, negli ambienti appenninici, date le condizioni ambientali e paleoambientali diverse da quelle delle alpi, tra cui il notevole sviluppo di un’idrologia di tipo carsico, è particolarmente difficile attribuire un’età precisa a queste forme. l’attività torrentizia che le ha create potrebbe essere stata particolarmente intensa quando nel bacino a monte esisteva un ghiacciaio, durante l’ultima fase di espansione glaciale che nell’appennino centrale ha avuto il suo massimo intorno ai 22 mila anni fa (giraudi & frezzotti, 1997). e’ quindi molto probabile che l’espulsione del cuneo sia avvenuta prima di questo momento del pleistocene superiore. 66.. ccoonnssiiddeerraazziioonnii ccoonncclluussiivvee la "diga in roccia" che ha determinato la formazione della forra, considerata nel suo contesto morfostrutturale, rappresenta un’evidenza di un movimento tettonico recente nell’ambito delle grande scarpata orientale della maiella. un’attenta analisi di questo sbarramento naturale permette di escludere sia che esso possa essere la conseguenza di un fenomeno di sovraescavazione a monte, sia che possa trattarsi della conseguenza di un movimento gravitativo nell’ambito della grande scarpata. nella fascia inferiore della stessa scarpata è possibile riconoscere altre strutture cuneiformi espulse in seguito a fenomeni tettonici, spesso associate a strutture di trascinamento degli strati (drag folds) (fig. 7). queste forme meriterebbero un’approfondita analisi strutturale. questo cuneo espulso, che ha rappresentato una sorta di "diga naturale", non costituisce un semplice dettaglio nell’ambito della grandiosa scarpata orientale della maiella, ma l’espressione del fatto che la scarpata è una forma tettonica ancora "viva", che mostra una notevole freschezza. dato il contesto erosivo è difficile trovare dei marker cronologici, in particolare di tipo sedimentario, che possano favorire una ricostruzione più precisa di momenti chiave di quest’evoluzione. non dimentichiamo tuttavia che all’interno dei canyon esistono numerose grotte carsiche che non sono mai state studiate, ed, in parte, neppure esplorate e che potrebbero aver registrato nei loro sedimenti eventi significativi della storia di questo versante della maiella. in ogni caso, la stretta forra, considerata nel suo contesto tettonico e geomorfologico, rappresenta una particolarità "geologica" meritevole sia di ulteriori studi, sia di interventi di tutela e valorizzazione nell’ottica di una didattica di tipo naturalistico-culturale. e’ certamente meritevole di essere censita come un importante "geosito", per il suo interesse rilevante per la conoscenza della storia della seconda montagna dell’appennino. rriinnggrraazziiaammeennttii esprimiamo un particolare ringraziamento a ezio burri e andrea borsato che ci hanno accompagnato sul terreno e hanno contribuito alla discussione sull’evoluzione della forma. questo lavoro è stato in parte finanziato dal miur cofin 2002 (prot. 2002043912_002). fig. 7 cuneo tettonico espulso nell’ambito della fascia inferiore della grande scarpata tettonica della maiella, in prossimità di fara di san martino. sul lato a valle si riconosce una piega di trascinamento. questa struttura presenta forti analogie con quella descritta, che si trova poche centinaia di metri più a ovest. a partially extruded wedge in the lower belt of the tectonic scarp of maiella near fara di san martino. a drag fold affects the downvalley side. this structure shows strong analogies with that described, which is located few hundred metres westwards. u. sauro & d. zampieri bbiibblliiooggrraaffiiaa ambrosetti p., bosi c., carraro f., ciaranfi n., panizza m., papani g., vezzani l. & zanferrari a. (1983) – neotectonic map of italy. consiglio nazionale delle ricerche, roma. casnedi r., crescenti u., d’amato c., mostardini f. & rossi u. (1981) il plio-pleistocene del sottosuolo molisano. geol. romana, 2200, 1-42. castiglioni g.b. (1958) – studi geologici e morfologici del territorio di baceno e premia (val d’ossola, alpi lepontine). mem. ist. geol. mineral. università di padova, 2200, 1-82. cello g., mazzoli s., tondi e. & turco e. (1997) – active tectonics in the central apennines and possibile implications for seismic hazard analysis in peninsular italy. tectonophysics, 227722, 43-68. crescenti u., crostella a., donzelli g. & raffi g. (1969) stratigrafia della serie calcarea dal lias al miocene nella regione marchigiano-abruzzese (parte ii – litostratigrafia, biostratigrafia, paleogeografia). mem. soc. geol. it., 88, 343-420. demangeot j. (1965) la montagne de la maiella. mém. et doc., in géomorphologie des abruzzes adriatiques. ed. du centre rec. doc. cart. geogr., cnrs, n.h.s., 403 pp, paris. ghisetti f. & vezzani l. (1983) deformazioni pellicolari mioceniche e plioceniche nei domini strutturali esterni dell’appennino centro-meridionale (maiella ed arco morrone gran sasso). mem. soc. geol. it., 2266, 563-577. ghisetti f. & vezzani l. (1997) interfering paths of deformation and development of arcs in the foldand-thrust belt of the central apennines (italy). tectonics, 1166, 523-536. ghisetti f. & vezzani, l. (1999a) depth and modes of pliocene-pleistocene crustal extension of the apennines (italy). terra nova, 1111, 67-72. ghisetti f. & vezzani l. (1999b) – geometrie deformative ed evoluzione cinematica dell’appennino centrale. studi geologici camerti, 1144, 127-154. giraudi c. & frezzotti m. (1997) late pleistocene glacial events in the central apennines, italy. quaternary-research, 4488 (3), 280-290. lavecchia g., brozzetti f., barchi m., menichetti m. & keller j.v.a. (1994) seismotectonic zoning in east-central italy deduced from an analysis of the neogene to present deformations and related stress fields. geol. soc. of am. bull., 110066, 11071120. sauro u. (1976) cenni morfologici sulla val di non. in: aspetti geografici del trentinoalto adige occidentale. ist. geogr. padova, xxii, 1974, 113-125. scisciani v., calamita f., bigi s., de girolamo c. & paltrinieri w. (2000) the influence of syn-orogenic normal faults on pliocene thrust system development: the maiella structure (central apennines, italy). mem. soc. geol. it., 5555, 193-204. scisciani v., tavarnelli e. & calamita f. (2002) the interaction of extensional and contractional deformations in the outer zones of the central apennines, italy. j. struct. geol., 2244, 1647-1658. tondi e. & cello g. (2003) – spatiotemporal evolution of the central apennines fault system (italy). j. geodynamics, 3366, 113-128. vecsei a., sanders d., bernoulli d., eberli g. & pignatti j. (1998) cretaceous to miocene sequence stratigraphy and evolution of the maiella carbonate platform margin, italy. sepm sp. publ., 6600, 53-74. vezzani l. & ghisetti f. (1998) carta geologica dell’abruzzo. scala 1:100.000. selca, firenze. 9 ms. ricevuto il 22 luglio 2003 testo definitivo ricevuto il 4 novembre 2003 ms. received: july 22, 2003 final text received: november 4, 2003 evidenze di movimenti tettonici ... imp.bigazzi& datazione di un livello cineritico del pleistocene medio: relazioni con sedimentazione, sollevamento e terrazzi marini nell’area crosia-calopezzati in calabria (italia) giulio bigazzi1 & luigi carobene2 1c.n.r., istituto di geoscienze e georisorse, via g. moruzzi, 1 – 56124 pisa 2dip.te.ris., università degli studi, corso europa, 26 – 16132 genova riassunto: bigazzi g. & carobene l., datazione di un livello cineritico del pleistocene medio: relazioni con sedimentazione, sollevamento e terrazzi marini nell’area crosia-calopezzati in calabria (italia). (it issn 0394-3356, 2004). nell’area di crosia-calopezzati, in destra del fiume trionto (calabria ionica), affiora un potente prisma sedimentario pleistocenico che, nelle parti più prossimali, è trasgressivo sui terreni miocenici. il sollevamento dell’area ha originato la formazione di 4 ordini di terrazzi marini, già descritti in un precedente lavoro; il rinvenimento e la datazione di un livello cineritico nel substrato argilloso pleistocenico ha permesso di ottenere una datazione indiretta degli stessi. il livello cineritico, per il quale è stata calcolata un’età di 450.000 anni ±10% con il metodo delle tracce di fissione, è stato infatti inquadrato stratigraficamente all’interno del corpo sedimentario; ciò ha consentito di trarre anche ulteriori deduzioni e ipotesi, sia cronologiche che quantitative, sul sollevamento e sull’emersione del prisma sedimentario pleistocenico e sulle velocità di sedimentazione. abstract: bigazzi g. & carobene l., fission-track dating of middle pleistocene ash layer: relationships to sedimentation, tectonic uplift and marine terraces in the crosia-calopezzati area (calabria, italy). (it issn 0394-3356, 2004). in the crosia-calopezzati area (ionian coast of calabria), east of the trionto river, crops out a pleistocene marine succession which is transgressive over miocene – pliocene (?) substratum (fig. 1; fig. 2). these sediments deposited during a lowering phase of the ionian margin, which caused the formation of important sedimentary basins in calabria and basilicata. a significant stage of knowledge of the geology of these regions during lower and middle pleistocene times had been already attained through studies that were performed on these basins. the uplift of the study area determined the formation of four orders of marine terraces (fig. 5) already described in a previous article (carobene, 2003). discovery and analysis of an ash layer interstratified with the pleistocene clayey substratum (fig. 3) provided the opportunity of inferring some considerations on the sedimentation rate and, consequently, on the onset of the sedimentation of the transgressive body. it was also possible to deduce some constraints on the beginning of its emersion as well as on the age of the marine terraces and on the uplift rate of the study area. the main results of this work can be summarized as follows (fig. 9): 1) age determination of the pyroclastic layer. the ash layer, referred to as “calopezzati ash”, looks poorly cemented, porous and white colored. dating of a population of glass shards separated from the calopezzati ash was performed using the fission-track method at the c.n.r. institute of geosciences and earth resources of pisa (fig. 4). an age of 450,000 a ± 10 % was determined (table 1). taking into account the close analogies found out with the pyroclastic layer named “parmenide ash” recognized in the nearby cutro basin, in the crotone peninsula (massari et alii, 2001), the deposition age of the calopezzati ash might be 420,000 a. 2) sedimentation rate. the position of the studied ash inside the sedimentary body allowed to compute a thickness of the overhanging clay cover of around 100 m and to deduce that sedimentation stopped at the end of mis 9 (280,000 a ago) (fig. 8). therefore, during the considered time span the average sedimentation rate was around 0.6 mm/a. 3) coastal area lowering (subsidence) and pleistocene sedimentation. based upon the mean sedimentation rate (see point 2 above) and taking into account the computed thickness of the sedimentary prism (around 400-500 m), we argue that sedimentation started during late lower pleistocene – early middle pleistocene times. 4) onset of the tectonic uplift. the onset of the uplift of the area is about coeval with the ash deposition, therefore an age of around 450,000 a can be deduced for the beginning of the uplift phase (fig. 6 a). 5) emersion of the sedimentary prism. obviously emersion is diachronic. it took place with evidence in correspondence with the eustatic lowering following the interglacial peak of mis 11, and it is testified by the sediments located at higher elevation (277 m, fig. 5); the sedimentary top does not coincide with the most recent sediments. 6) tectonic uplift and marine terracing. the interglacial high level subsequent the first emersion is attributed to the mis 9. it originated a wide terrace (i order terrace) nowadays to a great extent remodelled, with an inner margin at an elevation of 210 m (fig. 5). an algal limestone sample yielded a th/u ≥ 300.000 a (carobene, 2003). we computed an average uplift rate of 0.62 mm/a. we assume that the clayey sedimentation stopped with the eustatic lowering (fig. 8 – a e b). the following interglacial eustatic high level (mis 7) determined the formation of the ii order terrace which nowadays has an inner margin of 105÷120 m (chapter 4); the corresponding average uplift rate is 0.56 mm/a (tab. 2). the eustatic peak corresponding to mis 5.5 originated the iii order terrace, with an inner margin at present at around 65÷70 m; the average uplift rate is 0.50 mm/a (tab. 2). the last eustatic high of stage 5 (mis 5.1) produced the iv order terrace, which is of less importance than the previous ones as regards surface width and sediments thickness. the present elevation of its inner margin, 25÷30 m, allowed us to compute an average uplift rate of 0.46 mm/a. the chronological succession of the four orders of terraces and of the sedimentary top elevations (fig. 5 and tab. 2) proves an almost steady course of the uplift rate (fig. 6 – b), slightly decreasing with time (from 0.69 down to 0.46 mm/a). taking into account the uncertainties related to the attribution of the age to the palaeo-eustatic peaks and to the estimate of their original elevation, we have reckoned the variability interval of the computed uplift rate values reported above (fig. 7). parole chiave: livello cineritico, datazione con le tracce di fissione, terrazzi marini, tettonica quaternaria, eustatismo, pleistocene, calabria. keywords: ash layer, fission-track dating, marine terraces, quaternary tectonics, eustasy, pleistocene, calabria. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 151-163 152 g. bigazzi & l. carobene 1. premessa nella presente nota viene utilizzata una data ricavata da un livello piroclastico, denominato “cinerite di calopezzati”, presente nel substrato argilloso pleistocenico, per definire la cronologia dei terrazzi marini sviluppati nell’area di crosia-calopezzati. la datazione è stata effettuata con il metodo delle tracce di fissione; le relative procedure di laboratorio vengono esposte nel cap. 3. gli eventi successivi alla deposizione del livello cineritico sono stati: 1) il completamento del corpo sedimentario che costituisce il substrato; 2) il sollevamento; 3) la formazione dei terrazzi marini, in relazione alla progressiva emersione dell’area e alle oscillazioni glacioeustatiche. i 4 ordini di terrazzi riconosciuti (fig. 1) sono stati descritti in dettaglio da carobene (2003); in conformità con dette descrizioni, i margini interni dei terrazzi corrispondono ai “margini interni geometricamente ricostruiti”, ritenuti equivalenti alle paleolinee di riva. i terrazzi vengono qui ricordati brevemente. i ordine: crinali suborizzontali, risultato di un forte rimodellamento di una superficie terrazzata avente margine interno a circa 210 m. nel settore di crosia l’ampiezza massima raggiunge quasi 2500 metri; lembi di depositi marini sono stati osservati solo tra 130 e 169 m di quota. alcune faglie dislocano il terrazzo, contribuendo al notevole dislivello esistente tra margine interno e orlo esterno. ii ordine: relitti di superfici terrazzate, con ampiezza massima di 1000 m e margine interno a 105÷120 m. i depositi marini e continentali raggiungono uno spessore complessivo massimo di 45 m. iii ordine: relitti ancora ben conservati di superfici terrazzate, con margine interno a 64÷71 m; l’ampiezza massima è di 800 m, ma si riduce drasticamente a se del t. fiumarella. i depositi marini e continentali terrazzati sono presenti con uno spessore massimo di 25 m. iv ordine: è rappresentato da pochi relitti di superfici aventi ampiezza non superiore a 170 m e margine interno a 25÷30 m. i depositi terrazzati hanno spessori di pochi metri e a volte sono assenti. sono stati considerati i possibili errori che entrano in gioco nei calcoli (errori di quota, di età, di spessori, ecc.), al fine di verificare il possibile campo di variabilità dei tassi di sollevamento (tab. 2). fig. 1 carta geologica schematica della distribuzione del substrato pleistocenico nell’area di crosia e calopezzati. sono inoltre mappati i depositi o le forme riferibili ai quattro ordini di terrazzi marini rilevati (carobene, 2003). 1)substrato miocenico; 2)argille e sabbie del pleistocene; 3) forme relitte e lembi di depositi del i ordine; 4) depositi del terrazzo del ii ordine, 5) depositi del terrazzo del iii ordine; 6) forme relitte e lembi di depositi del terrazzo del iv ordine; 7) depositi colluviali, depositi alluvionali e depositi costieri recenti e attuali; 8) linea di correlazione dei terrazzi marini; 9) giaciture di strato; 10) ubicazione della cinerite; 11) centri abitati. geological schematic map showing the distribution of the pleistocene substratum in the crosia – calopezzati area. the deposits or the features referable to the surveyed four orders of marine terraces (carobene, 2003) are also shown. 1) miocene substratum; 2) pleistocene clays and sands; 3) relict landforms and deposit remains of the 1st order terrace; 4) deposits of the 2nd order terrace; 5) deposits of the 3rd order terrace; 6) relict landforms and deposit remains of the 4th order terrace; 7) present or recent colluvial, alluvial and coastal deposits; 8) correlation line of the marine terraces; 9) bed attitude; 10)location of the sx.819 ash level; 11) towns. 2. stratigrafia nell’area di studio (fig. 1) il substrato è costituito da un prisma sedimentario pleistocenico di notevole spessore, rilevato in dettaglio al fine di ricostruire al meglio la successione stratigrafica (carobene, dati inediti); il pleistocene di crosia è stato descritto precedentemente da panizza (1967). le variazioni litologiche e sedimentologiche riscontrate, considerate sia in senso verticale che areale (da mare verso terra), indicano che si tratta di una sequenza sedimentaria originatasi per una progressiva e prolungata fase trasgressiva, culminata in un alto stazionamento eustatico finale, che ha preceduto l’emersione dell’area. l’innalzamento del livello marino è coinciso con una lunga fase di subsidenza (periodo della sedimentazione della sequenza), alla quale è seguita una fase di sollevamento tettonico (periodo dell’emersione e del terrazzamento marino). la colonna stratigrafica di fig. 2 indica in modo schematico la litologia; le sabbie gialle basali sono riferibili al periodo trasgressivo, e sono ben osservabili nella zona costiera più interna (più sollevata); le argille siltose grigio-azzurre occupano invece la restante fascia di territorio fino al mare, tanto da non permettere l’osservazione della parte stratigrafica basale. la colonna rappresenta quindi la successione cronostratigrafica; lo spessore rappresentato è relativo, in quanto esso varia da un minimo a monte ad un massimo (calcolato) di 400 e forse maggiore di 500 m a valle. le giaciture di strato variano da circa 15° a monte a 9-10° a valle; esse hanno permesso una discreta valutazione degli spessori, complicata tuttavia dalla presenza di faglie. la messa in posto del livello della cinerite di calopezzati, così come le successive fasi sedimentarie, eustatiche e tettoniche, sono state riferite cronologicamente alla curva isotopica dell’ossigeno (cap. 5). l’età della cinerite (cap. 3) e dello spessore di argille (circa 100 m) che lo sovrasta, hanno permesso inoltre di ricavare indicazioni sulla velocità media della loro sedimentazione e quindi, estrapolando il dato all’intero spessore del prisma sedimentario, di avanzare un’ipotesi sull’inizio della sedimentazione (cap. 4.3). 3. la datazione del livello cineritico il livello cineritico è stato rinvenuto ed osservato, circa alla quota di 45 m, lungo la strada che unisce la stazione di calopezzati con il paese di calopezzati (fig. 1), sul fianco destro di una valle che ha inciso la superficie terrazzata estesa tra le quote di 75 e 96 metri (terrazzo del ii ordine – carobene, 2003). lavori di sbancamento lungo il versante argilloso hanno portato alla luce un livello biancastro, poroso, leggero, poco cementato, spesso alcuni centimetri; a volte la cinerite era presente in lenti o sacche più spesse, non cementata (fig. 3). il campione sx.819 è stato analizzato con il metodo sem – eds e con il metodo delle tracce di fissione per ottenerne rispettivamente la composizione chimica e l’età. 3.1. datazione con il metodo delle tracce di fissione la datazione con il metodo delle tracce di fissione si basa sulla scoperta, fatta negli anni 60 del secolo scorso, che minerali e vetri naturali mantengono memo153datazione di un livello cineritico ... ria degli eventi di fissione nucleare dell’u238 prodotti al loro interno nei tempi geologici. ogni evento di fissione produce nel solido nel quale avviene una regione danneggiata – una traccia cilindrica lunga ~ 10 ÷ 20 µm – chiamata “traccia latente” osservabile soltanto al microscopio elettronico, che può essere rivelata con un opportuno attacco chimico in modo da essere osservafig. 2 colonna stratigrafica schematica rappresentativa del substrato pleistocenico. lo spessore è stato calcolato in base ad una ricostruzione geometrica del corpo sedimentario basata sulle giaciture di strato; le sabbie basali sono affioranti nella parte prossimale (verso terra), mentre le argille sommitali sono affioranti nella parte distale (verso mare). la deposizione delle argille che sovrastano la cinerite (450.000 anni) è terminata con il mis 9 (vedi fig. 8). schematic stratigraphy of the pleistocene substratum. thickness was estimated through geometric reconstruction of the sedimentary body. the basal sands crop out in the proximal part (landward), whereas the upper clays crop out in the distal part (seaward). deposition of the clay overhanging the sx.819 ash level (450,000 years) stopped at the end of mis 9 (see also fig. 8). fig. 3 livello piroclastico bianco (cinerite di calopezzati) affiorante alla quota di circa 45 m; è venuto alla luce per un’azione di sbancamento del versante argilloso. white pyroclastic layer (calopezzati ash) cropping out at an elevation of about 45 m. it came to light in consequence of excavation works made on a clayey slope. 154 bile con un comune microscopio ottico. dato che la fissione nucleare spontanea dell’u238 avviene ad un tasso costante nel tempo, il numero di tracce di fissione accumulate nei tempi geologici, dette tracce “fossili”, in un minerale o in un vetro naturale è proporzionale al suo contenuto di uranio e al tempo trascorso dalla sua formazione. perciò la datazione con le tracce di fissione consiste nella determinazione della frazione di atomi di u238 che hanno subito la fissione nucleare. per calibrare lo sconosciuto contenuto di uranio, una frazione del campione viene irraggiata con neutroni termici in un reattore nucleare. l’irraggiamento produce la fissione indotta dell’isotopo u235: il numero di tracce rivelabili chimicamente dopo l’irraggiamento è proporzionale al contenuto di uranio. in pratica, quindi, una determinazione di età consiste nella stima di due densità superficiali di tracce – la densità di tracce fossili e la densità di tracce indotte – attraverso opportune tecniche di conteggio al microscopio. teoricamente non esistono limiti di età per l’applicazione del metodo delle tracce di fissione, ma in pratica, a causa della bassissima probabilità di verificarsi della fissione dell’u238, il contenuto di uranio di molti solidi non consente l’accumulo di un adeguato numero di tracce in tempi brevi. perciò, soltanto in casi particolari è possibile datare rocce recenti (età < 100.000 anni). benché le tracce di fissione siano state osservate in molti minerali, soltanto alcuni minerali pesanti, come ad esempio l’apatite, lo zircone e lo sfene e i vetri naturali vengono comunemente utilizzati. dato che la stabilità termica delle tracce in alcuni minerali è relativamente scarsa, l’applicazione più diffusa delle tracce di fissione è nel campo della termocronologia. particolare importanza riveste l’apatite, sia per la sua larga diffusione nelle rocce anche sedimentarie, sia per la fascia di temperature alle quali le tracce sono sensibili (da ~ 60°c a ~ 120°c). l’analisi dell’apatite con il metodo delle tracce di fissione si è rivelato un potente strumento per lo studio della storia dell’esumazione delle catene montuose o dello studio dell’evoluzione dei margini continentali. le tracce di fissione hanno fornito un contributo significativo anche nella datazione delle rocce vulcaniche, come ad esempio nello studio crono-stratigrafico in aree vulcaniche o nel campo della tefrocronologia. a questo proposito rivestono particolare importanza i vetri naturali. infatti l’unica fase databile di molti tefra consiste di una popolazione di frammenti di vetro, difficilmente databile con altre tecniche (walter, 1989). una descrizione esauriente della datazione con il metodo delle tracce di fissione e delle sue applicazioni è riportata da wagner & van den haute (1992). la cinerite di calopezzati è stata analizzata usando le metodologie messe a punto nell’istituto di geoscienze e georisorse del cnr di pisa (vedi ad esempio bigazzi et alii, 2000, espizua et alii, 2002). una frazione del vetro sx.819 è stata irraggiata con neutroni nella posizione lazy susan (rapporto cd 6,5 per au e 48 per co) del reattore del lena dell’università di pavia. dopo l’irraggiamento due frazioni del campione – una per il conteggio delle tracce fossili dovute alla fissione spontanea dell’u238 e l’altra per il conteggio delle tracce indotte dell’u235 prodotte dall’irraggiamento – sono state montate in resina epossidica, pulimentate in modo da esporre una superficie interna dei grani di vetro e attaccate per 90 s in hf 20% a 40°c per la rivelazione delle tracce. il conteggio è stato effettuato con un microscopio leica orthoplan a 500 x, utilizzando un oculare equipaggiato con una griglia, mentre le dimensioni delle tracce (l’asse maggiore degli ellissoidi che rappresentano l’intersezione delle tracce rivelate con la superficie dei grani) sono state misurate a 1000 x, utilizzando lo strumento leica-microvid accoppiato al microscopio. i risultati sono riportati in tab. 1. per il conteggio delle tracce è stata adottata la tecnica detta del “conteggio puntuale”, introdotta già negli anni ’60 (fleischer et alii, 1965), ma soltanto più recentemente utilizzata diffusamente (naeser et alii, 1982, westgate, 1989). secondo questa tecnica un campo di osservazione al microscopio viene considerato 1 se un punto di riferimento opportunamente scelto – tab. 1 tratt. termico: trattamento termico per la determinazione dell’età di plateau; ρs (ρi): densità superficiale delle tracce fossili (indotte); ns (ni): tracce fossili (indotte) contate; p(χ2): probabilità di ottenere il valore di χ2 calcolato nell’applicazione del test per confrontare la distribuzione dei conteggi delle tracce indotte con una distribuzione di poisson; ds/di: rapporto tra le dimensioni medie delle tracce fossili e indotte; età app.: età apparente; età corr.: età corretta con il metodo delle dimensioni o età di plateau. parametri usati per il calcolo dell’età: λ = 1,55125 x 10-10 a-1; λf = 8,46 x 10-17 a-1; σ = 5,802 x 10-22 cm2; 238u/235u = 137,88. la dose di neutroni, 1,53 x 1015 cm-2, è stata determinata usando il vetro standard ec-jrc-irmm-540 (de corte et alii, 1998), attraverso il conteggio di 6657 tracce sulla superficie dei detector esterni di muscovite giustapposti al vetro standard durante l’irraggiamento. gli errori sperimentali sono la propagazione degli errori di conteggio delle tracce e dell’errore introdotto dalla tecnica del conteggio puntuale (bigazzi & galbraith, 1999). tratt. termico: thermal treatment imposed for the plateau age determination; ρs (ρi) spontaneous (induced) track density; ns (ni): spontaneous (induced) track counted; p(χ2): probability of obtaining chi-square value for the induced track count distribution tested against a poisson distribution; ds/di: spontaneous to induced track size ratio; età app.: apparent age; età corr.: size-corrected or plateau age. the following parameters were used for age calculation: λ = 1.55125 x 10-10 a-1;λf = 8.46 x 10-17 a-1; σ = 5.802 x 10-22 cm2; 238u/235u = 137.88. samples were irradiated in the lazy susan (cd ratio 6.5 for au and 48 for co) facility of the triga mark ii reactor of lena, university of pavia (italy). the neutron fluence, 1.53 x 1015 cm-2, was determined using the ec-jrc-irmm-540 standard glass (de corte et al., 1998). 6657 tracks were counted on muscovite external detectors juxtaposed to the standard glass during irradiation. experimental errors are propagation of poisson counting errors and of the additional error due to the application of the point-counting technique (bigazzi & galbraith, 1999). campione ρs ns ρi ni p(χ2) ds/di età app. ± 1σ età corr. ± 1σ tratt. termico (cm-2 ) (cm-2 ) (%) (ma) (ma) sx.819 2.360 455 511.500 2.220 10 0,86 0,35 ± 0,03 0,44 ± 0,04 5h 180°c 2.222 104 372.000 512 90 1,01 0,45 ± 0,08 g. bigazzi & l. carobene 155 ad esempio il centro della griglia montata nell’oculare – si trova su una superficie di vetro utile per il conteggio, cioè su una area nella quale una traccia, se presente, sarebbe osservabile. altrimenti, cioè se il punto di riferimento si trova sulla resina o su una porzione di vetro nella quale una traccia non sarebbe identificabile, il campo è considerato 0. in questo modo il risultato finale del conteggio è una densità virtuale y/x, dove y è il numero di tracce e x è il numero dei punti su vetro. la frazione della superficie utile per il conteggio è stimata da x/n, dove n è il numero totale dei campi osservati. il conteggio puntuale consente l’analisi di superfici molto più ampie in tempi più brevi, dato che non è necessaria la stima della superficie utile dei singoli grani di vetro, tuttavia questa tecnica introduce un errore sperimentale addizionale che non può essere ignorato, anche se nel caso di basse densità di tracce questo errore può diventare anche molto modesto (bigazzi, 1999; bigazzi & galbraith, 1999). nei vetri naturali la stabilità delle tracce fossili nei tempi geologici è piuttosto scarsa: un certo tasso di cancellamento (annealing) che corrisponde a un accorciamento della lunghezza rivelabile dall’attacco chimico delle tracce stesse si produce in genere anche a temperatura ambiente. le tracce che hanno subito un certo tasso di annealing sono rivelate con efficienza ridotta. per questo motivo le età determinate con il metodo delle tracce di fissione nei vetri sono comunemente età ridotte, dette “età apparenti”, a meno che non venga applicata una tecnica di correzione. storzer & wagner (1969) hanno mostrato che la quantità di annealing può essere stimata dal rapporto tra le dimensioni delle tracce fossili e delle tracce indotte, ds/di, dove le tracce indotte sono assunte come tracce indisturbate di riferimento. una riduzione del rapporto ds/di (ds/di < 1) indica che le tracce fossili hanno subito un certo tasso di annealing, tanto più elevato quanto minore è il rapporto ds/di. il vetro sx.819 presenta un moderato tasso di annealing delle tracce fossili (ds/di = 0,86, tab. 1 e fig. 4). l’età di formazione del vetro è stata quindi stimata con il metodo delle dimensioni, utilizzando una curva di correzione delle età apparenti che mette in relazione la riduzione delle dimensioni con la corrispondente riduzione delle densità di tracce (storzer & wagner, 1969). abbiamo quindi determinato l’età di plateau, proposta da storzer & poupeau (1973) per correggere le età apparenti, che consiste nel ristabilire, attraverso trattamenti termici opportuni, una stessa efficienza di rivelazione delle tracce fossili ed indotte. seguendo la pratica comune, un solo trattamento termico è stato utilizzato in questo lavoro (arias et alii, 1981; westgate, 1989). il raggiungimento della condizione di plateau – una identica efficienza di rivelazione delle tracce fossili ed indotte – è testimoniato dal valore di ds/di, che dopo il trattamento termico diventa circa 1 (tab. 1, fig. 3). l’età corretta con il metodo delle dimensioni e l’età di plateau del campione sx.819, che sono considerate una stima affidabile dell’età di formazione del vetro, almeno nel caso di storie termiche semplici (wagner & van den haute, 1992), sono consistenti. l’età assegnata al livello piroclastico sx.819 (vedi tab. 1) permette di effettuare una possibile corrispondenza con uno dei livelli ritrovati nell’area di montalbano jonico (avanfossa bradanica dell’appennino), dove approssimativamente tra 400. e 500.000 anni ricadono ben 5 orizzonti piroclastici (v5 v6 – v7 – v8 – v9) (sezione vecchietto) (ciaranfi et alii, 2001). più preciso è il riferimento al bacino di crotone in calabria (massari et alii, 2001), dove in località marcedusa (valle di manche) è stato riconosciuto un livello piroclastico denominato “parmenide ash” contenuto nell’unità di s. mauro, che comprende i sedimenti più recenti del riempimento del sub-bacino di s. mauro (bacino di crotone). in tale località il livello piroclastico marca praticamente l’emersione del corpo sedimentario, avvenuta “durante la fase iniziale della transizione mis 12 – mis 11” (ovvero 420. – 410.000 anni). esso si presenta composto da cinerite pura di color bianco. la coincidenza è quindi straordinaria sia per quanto riguarda l’età, sia per quanto riguarda il colore; inoltre la piccola distanza tra i due affioramenti, circa 60 km, depone a favore di una loro corrispondenza. l’età “più probabile” della cinerite del campione sx.819 potrebbe pertanto essere pari a 420.000 anni, per l’affinità con il “parmenide ash” (massari et alii, 2001). nel testo è stata comunque utilizzata l’età misurata. 4. sedimentazione, sollevamento e terrazzi marini la datazione della “cinerite di calopezzati” ha permesso di definire con buona precisione il quadro cronologico degli eventi sedimentari e del terrazzamento marino conseguente all’emersione dell’area crosiacalopezzati. tali eventi sono stati riferiti alla curva delle variazioni isotopiche dell’ossigeno (prell et alii, 1986), in quanto è ormai accettata la corrispondenza: alti eustatici interglaciali-picchi caldi climatici-massimi valori negativi del rapporto isotopico o18/o16. la sequenza sedimentaria, rilevata e campionata da carobene negli anni ’90, è purtroppo ancora priva di datazioni bio-stratigrafiche. comunicazioni verbali e l’analogia con la vicina sequenza sedimentaria di tarsia (valle del crati) (carobene et alii, 1997), unitamente allo studio dei terfig. 4 distribuzione delle dimensioni delle tracce rivelate nel vetro della cinerite di calopezzati prima (rapporto tra le dimensioni medie delle tracce fossili ed indotte ds/di = 0,86) e dopo il trattamento termico per la misura dell’età di plateau (ds/di = 1,01). size distribution of the fission tracks developed on glass shards from the calopezzati ash before (spontaneous to induced track-size ratio ds/di = 0.86) and after the thermal treatment imposed for the plateau age determination (ds/di = 1.01). datazione di un livello cineritico ... 156 razzi marini (carobene, 2003), avevano comunque permesso di ipotizzare la sua appartenenza al pleistocene medio; la datazione della cinerite ha confermato l’ipotesi, fornendo il vincolo cronologico mancante. nella fig. 5 è schematizzato il prisma sedimentario ed il terrazzamento marino; la sequenza deposizionale (descritta sommariamente in questa sede), è il risultato di una complessa sedimentazione avvenuta in un regime di subsidenza; la trasgressione è culminata in un alto stazionamento eustatico, al quale è seguita l’emersione per il perdurare di un regime di sollevamento tettonico. pertanto il prisma sedimentario è costituito da un insieme di sistemi deposizionali trasgressivi, testimoniati dai corpi sabbiosi basali illustrati in fig. 1, e da un insieme di sistemi deposizionali di alto stazionamento che, nelle parti centrali e distali del bacino hanno originato una sedimentazione prevalentemente argillosa, con spessori di centinaia di metri. da notare che, durante la fase di sollevamento, il depocentro della sedimentazione si è spostato progressivamente verso mare. nella parte medio-alta delle argille è stato rinvenuto il livello cineritico datato 450.000 anni (cap. 3); lo spessore di argille che lo sovrasta stratigraficamente è la testimonianza della sedimentazione avvenuta sicuramente durante l’alto eustatico corrispondente al mis 11 (picco massimo a 405.000 anni) e continuata per un certo periodo che verrà definito più avanti al paragr. 4.3. il nuovo regime di sollevamento tettonico causò l’emersione del prisma sedimentario prima nelle aree prossimali, successivamente nelle aree distali del bacino. i sedimenti più alti in quota, che segnano l’inizio dell’emersione, si rinvengono nell’area di crosia (fig. 1) a 277 m s.l.m. (cozzo s. pietro); essi sono costituiti da sabbie inclinate di pochi gradi verso mare, poggianti su argille mioceniche, per uno spessore di 25 m. le sabbie possono testimoniare l’ultimo alto eustatico interglaciale prima dell’emersione; a testimonianza di questo livello marino più alto vi sono crinali suborizzontali estesi verso sud fino alla quota di 300 m, sia in destra che in sinistra del fiume trionto. in corrispondenza di calopezzati il crinale si sviluppa infatti per 2200 m circa, mentre in corrispondenza di crosia lo sviluppo raggiunge i 5 km! 4.1. la datazione dei terrazzi marini per la risoluzione del problema sono stati distinti: i dati a disposizione, le ipotesi più attendibili, le relative deduzioni e, infine, le considerazioni conclusive. i dati 1) nell’area sono riconoscibili 4 ordini di terrazzi, con margine interno a 210 m (i ord.), a 105÷120 m (ii ord.), a 65÷70 m (iii ord.) e a 25÷30 m (iv ord.) s.l.m. essi sono intagliati nel substrato pleistocenico in gran parte argilloso (fig. 1). 2) il terrazzo del ii ordine (t2 in fig. 5) taglia dette argille, nelle quali è stato riconosciuto (alla quota di 45 m) il livello cineritico bianco, datato 450.000 anni ± 10% (cinerite di calopezzati). 3) lo spessore di argille che sovrasta la cinerite è attualmente valutabile in circa 100 m (±20); la misura si ricava dall’analisi della sezione geologica. 4) il substrato pleistocenico affiora (con sabbie litorali) alla quota massima di 277 m (cozzo s. pietro). 5) un esteso crinale con andamento suborizzontale si estende da tale quota verso monte per 5 km; esso potrebbe essere il relitto di una superficie di abrasione marina avente margine interno a 300 m s.l.m. 6) i depositi terrazzati del i ordine sono molto erosi. lembi relitti di calcari algali hanno fornito un’età th/u incerta ≥ 300.000 anni. 7) i depositi marini del ii e del iii ordine di terrazzi sono invece potenti, rispettivamente, fino a 40 e fino a 20 metri. 8) il terrazzo del iv ordine si presenta di ridotte dimensioni e con depositi che hanno uno spessore massimo di qualche metro. le ipotesi in base ai dati, si ritengono valide le seguenti affermazioni: 1) i terrazzi del i, ii e del iii ordine vanno riferiti a distinti e consecutivi periodi interglaciali, a loro volta correlabili a distinti mis delle curve paleoclimatiche. tale fig. 5 rappresentazione schematica dei terrazzi marini. p.l. = paleolivello marino corrispondente al top dei sedimenti; è stato attribuito al mis 11. i depositi più alti affiorano alla quota di 277 m; essi non costituiscono i depositi più recenti. c. = livello della cinerite di calopezzati rinvenuto alla quota di 45 m. t1, t2, t3, t4 = terrazzi marini attribuiti, rispettivamente, ai mis 9, 7, 5.5 e 5.1 (disegno non in scala). per notizie dettagliate vedi carobene (2003). schematic sketch of the four orders of marine terraces. p.l. = marine palaeo-level corresponding to the top of the sedimentary deposits, it was attributed to mis 11. the higher deposits crop out at an elevation of 277 m; they do not consist of the most recent sediments. c. = calopezzati ash layer, recognised at an elevation of 45 m. t1, t2, t3, t4 = marine terraces attributed to mis 9, 7, 5.5 and 5.1, respectively (non-scale drawing). see carobene (2003) for further details. g. bigazzi & l. carobene relazione è basata sulla consistente differenza altimetrica esistente tra i tre margini interni dei terrazzi, sulla grande estensione delle superfici (da 2400 a 800 metri), sullo spessore e sui caratteri stratigrafici dei depositi. 2) il terrazzo del iv ordine, viceversa, va riferito ad un substage isotopico di importanza minore, sia per la debole differenza altimetrica che lo separa dal terrazzo del iii ordine (35-40 m), sia per la sua ridotta ampiezza (inferiore a 170 m), sia per le caratteristiche dei depositi terrazzati. 3) il deposito sabbioso marino di quota 277 m ed il crinale con margine interno alla quota di 300 m testimoniano un lungo periodo di alto livello eustatico. 4) il sollevamento tettonico successivo a questo periodo interglaciale porta alla progressiva emersione del corpo sedimentario pleistocenico. 5) con il proseguire del sollevamento, il successivo periodo di alto eustatico interglaciale porta alla formazione del i ordine di terrazzi. le deduzioni 1) i 100 metri di argilla che sovrastano la cinerite sono più recenti di 450.000 anni, ma più antichi dell’interglaciale (mis) durante il quale si è formato l’ampio terrazzo del ii ordine. 2) il terrazzo del ii ordine non può essere attribuito al mis 11, con picco a 405.000 anni (ed a maggior ragione ad uno più antico), in quanto sarebbe mancato il tempo necessario alla deposizione delle argille post-cinerite. quindi non può essere più antico del mis 9. 3) il terrazzo del ii ordine non può essere attribuito al mis 5, in quanto ciò obbligherebbe ad attribuire i terrazzi del iii e del iv ordine ai substages 5.3 e 5.1. ciò contrasta col fatto che il iii ordine corrisponde in realtà ad un terrazzo molto importante, con uno spessore di depositi marini che raggiunge i 20 m e con superfici terrazzate ampie fino a 800 m. inoltre il tasso di sollevamento del terrazzo del ii ordine (attribuito al mis 5) risulterebbe quasi doppio di quello degli ordini iii e iv. l’origine del terrazzo del ii ordine va quindi attribuita o al mis 7 o al mis 9. 4) l’attribuzione del terrazzo del ii ordine al mis 9 comporterebbe invece: che la deposizione delle argille post-cinerite (spessore circa 100 m), tagliate dal terrazzo del ii ordine, sia avvenuta nell’intervallo di tempo tra 450.000 anni e la fine dell’alto eustatico (circa 370.000 anni fa) corrispondente al mis 11; che il terrazzo del iii ordine venga attribuito di conseguenza al mis 7; che il terrazzo del iv ordine venga attribuito al mis 5. queste tre possibilità sono poco probabili; la prima comporta infatti che la deposizione dei 100 m di argilla sia avvenuta in un arco di tempo breve, durante l’alto eustatico interglaciale corrispondente al mis 11, con una batimetria che andava rapidamente diminuendo durante la fase finale dello stage, fino ad annullarsi; ciò a causa dell’abbassamento eustatico e dell’avvenuta sedimentazione. la terza possibilità va esclusa per quanto già detto sopra (ipotesi 2); ciò esclude la possibilità due. pertanto si può dedurre, in base ai dati a disposizione, che l’attribuzione al mis 7 del terrazzo del ii ordine sia la più attendibile. le considerazioni conclusive l’attribuzione del terrazzo del ii ordine al mis 7, comporta che il i ordine vada riferito al mis 9 e l’emersione dell’area al mis 11. è probabile che l’emersione abbia avuto inizio già durante o subito alla fine del mis 11, a causa di un regime di sollevamento cominciato da qualche tempo. il cambiamento di regime tettonico, dalla fase subsidente a quella di sollevamento, determina un periodo di stasi tettonica che probabilmente si somma al periodo dell’alto eustatico interglaciale mis 11, manifestatosi tra 370. e 415.000 anni fa circa, con picco massimo a 405.000 anni (substage 11.3). ciò può spiegare la formazione dell’ampia superficie di erosione, la cui testimonianza è oggi un crinale suborizzontale esteso fino a 5 km (vedi sopra) e fino alla quota di 300 m. l’assenza di terrazzi a quota più elevata esclude che il sollevamento sia iniziato precedentemente. lo schema di fig. 6 sintetizza le fasi del sollevamento dell’area e del conseguente terrazzamento marino, avvenute posteriormente alla deposizione del livello cineritico sx.819. 157 fig. 6 schema che sintetizza le fasi dell’emersione del corpo sedimentario pleistocenico, del suo sollevamento ed il conseguente terrazzamento marino (b). l’emersione avviene con la fine del mis 11, che corrisponde ai sedimenti più alti in quota; il i ordine di terrazzi si forma in corrispondenza del mis 9; il ii ordine corrisponde al mis 7; il iii ordine al mis 5.5; il iv ordine al mis 5.1. il periodo della subsidenza (a) è stato ipotizzato in base al tasso di sedimentazione medio, considerato pari a 0,6 mm/a ± 30% (paragr. 4.3). sketch synthesizing the emersion phases of the pleistocene sedimentary body, of its uplift and of the consequent marine terracing (b). emersion occurred with the end of mis 11, which corresponds to the sediments located at higher elevation. the 1st order of terraces formed connected with mis 9, whereas the 2nd, 3rd and 4th orders correspond to mis 7, mis 5.5 and mis 5.1, respectively. the subsidence period (a) was hypothesised through an estimated average sedimentation rate of 0,6 mm/a ± 30% (see paragr. 4.3). datazione di un livello cineritico ... terrazzo del i ordine. si forma durante il mis 9, manifestatosi tra 280. e 335.000 anni fa, con picco massimo a 330.000 anni (substage 9.3). sia l’ampiezza (fino a 2500 metri), sia il dislivello in quota tra margine interno (210 m) e orlo esterno (130 m), indicano che alla costruzione della superficie terrazzata hanno contribuito gli alti eustatici dei substages (due o tre, a seconda delle curve isotopiche) appartenenti all’intero stage isotopico 9. al dislivello sopra evidenziato hanno contribuito in parte anche le faglie, attivatesi in questa prima fase di forte sollevamento. terrazzo del ii ordine. essendo il terrazzo immediatamente più basso, è stato riferito al mis 7; questo lungo periodo interglaciale, esteso tra 185. e 245.000 anni, è caratterizzato da 3 – 4 substages; dalle curve isotopiche o dei paleolivelli di stazionamento del mare non si evince in modo univoco qual’è stato il picco più importante (chappell & shackleton, 1986; waelbroeck et alii, 2002; williams et alii, 1988; winograd et alii, 1997, ecc.). in questa sede pertanto si attribuisce al picco maggiore del mis 7 un’età intermedia di 220.000 anni; tale valore è probabilmente affetto da un errore del ±10% circa. la quota attuale del margine interno del terrazzo è a 105÷120 m. terrazzo del iii ordine. è riferibile al successivo interglaciale mis 5, che si è sviluppato tra 80. e 135.000 anni. in questo caso però il terrazzo va attribuito al picco massimo centrato a 125.000 anni (substage 5.5, con durata di almeno 10.000 anni) per almeno due ragioni: 1) la sua ampiezza e lo spessore di depositi che lo caratterizza sono sensibilmente più ridotti rispetto ai terrazzi più alti; 2) esiste un iv ordine di terrazzi, più basso in quota, che deve essere attribuito ad un alto eustatico successivo appartenente al mis 5 (vedi avanti). il margine interno è alla quota di 65÷70 m. terrazzo del iv ordine. ha margine interno alla quota di 25÷30 m, ampiezza molto ridotta rispetto ai precedenti e uno spessore di sedimenti debole e a volte mancante. la sua attribuzione al 5.1 anziché al 5.3 è ritenuta più probabile, in quanto l’ultimo terrazzamento è generalmente il meglio conservato. 4.2. ipotesi sulle velocità di sollevamento la cronologia degli eventi sopra esposta permette di effettuare calcoli sulle velocità di sollevamento riferite sia al livello di chiusura (nella parte a monte) del prisma sedimentario che costituisce il substrato, sia dei quattro ordini di terrazzi che lo incidono a quote più basse. per i calcoli si fa riferimento alla cronologia delle curve delle paleotemperature degli isotopi dell’ossigeno. per valutare il sollevamento effettivo si è inoltre tenuto conto della probabile paleoquota dei singoli alti livelli interglaciali, desunta da vari autori (aharon & chappell, 1986; bender et alii, 1979; chappell & shackleton, 1986; dodge et alii, 1983; mush et alii, 1994; pirazzoli et alii, 1991; shackleton, 1987; williams et alii, 1998). nella colonna 8 della tab. 2 è riportato il tasso medio di sollevamento. il picco interglaciale più alto (mis 11), successivo alla cinerite sx.819, ha avuto il suo massimo a 405.000 anni; un lembo relitto di sedimenti del substrato è riconoscibile alla quota di 277 m (cozzo s. pietro), mentre il crinale suborizzontale esteso a monte ha il margine interno alla quota di 300 m. il tasso medio di sollevamento calcolato è pari a 0,69 mm/a. il picco interglaciale immediatamente più basso (mis 9) ha il suo massimo a 330.000 anni; la quota attuale del margine interno del terrazzo corrispondente è a 210 m. il tasso di sollevamento medio risultante è di 0,62 mm/a. il picco interglaciale successivo (mis 7) ha il suo massimo a 220.000 anni; la quota attuale del margine interno del corrispondente terrazzo è a 105÷120 m. il tasso di sollevamento medio è di 0,56 mm/a. il picco interglaciale (mis 5.5) ha avuto il suo massimo a 125.000; la quota del margine interno del terrazzo è a 64÷71 m. il tasso di sollevamento risultante è di 0,50 mm/a. il terrazzo più basso, con margine interno a 25÷30 m, viene fatto corrispondere al sottostadio mis 5.1, che ha avuto il suo massimo circa 82.000 anni fa. la velocità di sollevamento è pari a 0,46 mm/a. la tab. 2 riassume i valori sopra esposti; si ritiene che le età riportate in col. 3 siano affette da un errore del 5-10%. nella col. 5 sono riportati i presunti valori delle paleoquote di stazionamento diverse dall’attuale livello del mare, desunte dalla bibliografia (vedi carobene, 2003, cap. 3); questi valori sono sicuramente affetti da un errore che, in questa sede, è stato ritenuto pari a ±5÷10 m. si può osservare (col. 8) che i tassi diminuiscono da 0,69 a 0,46 mm/a, dal livello più antico al livello più recente; ciò è coerente con il quadro tettonico dell’area (carobene, 2003), dove l’attività di faglie quaternarie ha sollevato maggiormente la zona a monte, con rigetti di alcune decine di metri. non si può escludere tuttavia che le velocità iniziali di sollevamento siano andate leggermente scemando nel tempo. in ogni caso, sulla base degli errori che affliggono i dati delle colonne 3 (età) e 5 (paleoquote), è stata calcolata la variabilità dei tassi di sollevamento (tab. 2 col. 9 e fig. 7). 4.3. ipotesi sulle velocità di sedimentazione la datazione dei terrazzi sopra riportata permette di effettuare anche un calcolo della velocità media di sedimentazione delle argille che si sono deposte al di sopra del livello cineritico sx.819; lo spessore, calcolato in base a ricostruzioni geometriche basate sulla inclinazione degli strati, risulta di circa 100 metri ±20 m. la successiva formazione dei terrazzi marini ha intagliato il corpo argilloso, asportandovi la parte superiore, tanto che oggi l’orizzonte cineritico è stato rinvenuto, alla quota di 45 m, al di sotto della superficie terrazzata del ii ordine (che localmente presenta la quota massima a 95 metri) (vedi cap. 3). si dimostra che la deposizione dei 100 m di argilla sovrastanti la cinerite terminò con l’alto eustatico corrispondente al mis. 9, durante il quale la batimetria del fondo marino (in corrispondenza della cinerite ) non superava i 65 m circa (fig. 8 – a). tale valore di profondità era compatibile con la sedimentazione argillosa; successivamente (con l’abbassamento eustatico e con il proseguire del sollevamento dell’area), le condizioni non furono più favorevoli alla sedimentazione. infatti, durante il mis 7 il mare intagliava già il corpo argilloso, essendo più basso del top dei sedimenti (fig. 8 – b). si può pertanto concludere che la sedimentazione (in quel punto) deve essersi necessariamente conclusa con la 158 g. bigazzi & l. carobene pari a 0,6 mm/a circa. il valore così ritrovato è sicuramente afflitto da errori derivanti dalla incertezza del reale spessore di argille post-cinerite, dalla reale durata della deposizione e dalla variabilità del tasso di sedimentazione durante glaciali e interglaciali, per cui si è calcolata una variabilità compresa tra 0,4 e 0,8 mm/a. il valore di 0,6 mm/a fornisce tuttavia utili indicazioni per ricavare l’età della colonna stratigrafica di fig. 1. lo spessore calcolato di oltre 400 m (confermato da un pozzo presente in zona di 330 m completamente in argille!), permette di ipotizzare che la sequenza sedimentaria si sia deposta in un periodo di 635.000 anni, tenendo costante il tasso di 0,6 mm/a. l’inizio della sedimentazione risalirebbe quindi a 985.000 anni fa circa (170.+535.+280.000); tenendo conto di errori o incertezze, il campo di variabilità si estende da 800. a 1.200.000 anni circa). ciò è coerente con quanto dedotto dallo studio della successione pleistocenica di tarsia nella valle del crati (carobene et alii, 1997), che ha uno spessore complessivo di 210 m circa, essendosi deposta con un regime di minor subsidenza. in base a datazioni basate su foraminiferi, ostracodi e nannoplancton 159 tab. 2 dati relativi ai 4 ordini di terrazzi marini e al top del corpo sedimentario pleistocenico, che costituisce il substrato. il sollevamento medio (col. 8) subito dai terrazzi è stato calcolato tenendo conto dei sollevamenti effettivi (col. 6) e mediando i valori della col. 7. la col. 9 riporta la variabilità dei tassi di sollevamento causata sia dalle differenze di quota del m.i. dei terrazzi (col. 2), sia dell’incertezza delle quote originarie dei paleostazionamenti (col. 5). data related to the four orders of marine terraces and to the top of the pleistocene sedimentary body, which constitutes the substratum. the average uplift (col. 8) experienced by the terraces was computed taking into account the real uplift amounts (col. 6) and averaging the uplift rate values shown in col. 7. the variability of the average uplift rates owing to both the elevation differences of the inner margin (m.i.) of the terraces (col. 2), as well as to the uncertainties related to the original elevation of the palaeo-standing phases (col. 5) is shown in col. 9. 1 2 3 4 5 6 7 8 9 elemento quota m.i. età mis quota solletassi tasso variabilità considerato s.l.m. del picco curva probabile dei vamento di sollemedio dei tassi dovuta più alto paleotempaleostazionavamento agli errori (metri) (annix1000) perature menti (metri) (metri) (mm/anno) (mm/anno) (mm/anno) top 277 ÷ 300 405 11.3 + 10 ? 267 ÷ 290 0,66 ÷ 0,72 0,69 0,65 ÷ 0,80 sedimentazione i ordine terrazzi 210 330 9.3 + 5 ? 205 0,62 0,62 0,58 ÷ 0,70 ii ordine terrazzi 105 ÷120 220 7.3 10 ? 115 ÷ 130 0,52 ÷ 0,59 0,56 0,45 ÷ 0,65 iii ordine terrazzi 65 ÷ 70 125 5.5 + 5 ? 60 ÷ 65 0,48 ÷ 0,52 0,50 0,38 ÷ 0,58 iv ordine terrazzi 25 ÷ 30 82 5.1 10 ? 35 ÷ 40 0,43 ÷ 0,49 0,46 0,35 ÷ 0,55 fig. 7 il tasso medio di sollevamento dell’area decresce da 0,69 a 0,46 mm/a. il campo di variabilità attribuito ai singoli valori è stato calcolato: 1) in base alla variabilità della quota del margine interno dei terrazzi (m.i.); 2) in base all’errore (circa 10.000 anni) che si fa nell’attribuire una età ben precisa ai mis e 3) in base ad un errore nella valutazione della paleoquota originaria dei massimi livelli interglaciali (circa ± 10 m). the average uplift rate of the area decreased from 0.69 down to 0.46 mm/a. the variability interval of the individual uplift rate values was estimated taking into account 1) the variability of the elevation of the terrace inner margin (m.i.), 2) the uncertainty related to the attribution of a given numerical value to the age of a certain mis (around 10,000 years) and 3) the error of the estimate of the original palaeo-elevation of the maximum inter-glacial levels (around ± 10 m). fine dell’alto stazionamento corrispondente al mis 9, ovvero 300.-280.000 anni fa (al massimo). i 100 m di argilla sovrastanti la cinerite si sarebbero deposti in un arco di tempo non superiore a 170.000 anni (da 450. a 280.000 anni), con velocità media di sedimentazione datazione di un livello cineritico ... calcareo, l’intera successione di tarsia è stata infatti attribuita al pleistocene medio (“ioniano” in cita & castradori, 1995). nel caso della successione di crosia-calopezzati non è in realtà conosciuta la base della successione nella parte mediodistale, per cui non si può escludere una sua continuità di sedimentazione con il pleistocene inferiore. inoltre la superficie trasgressiva è diacrona, per cui il valore calcolato è valido sulla verticale del livello cineritico. 5. conclusioni nell’area di crosiacalopezzati, in destra del fiume trionto in calabria, affiora una successione marina pleistocenica trasgressiva (almeno nella parte prossimale) sul substrato miocenico. essa è il risultato di una fase di abbassamento del margine ionico, che ha originato importanti bacini di sedimentazione in calabria e in basilicata; il loro studio ha già fornito risultati rilevanti per la conoscenza del pleistocene inferiore e medio. per il bacino crotonese si segnala massari et alii (2001, cum bibl.) e massari et alii (2002) e per il bacino lucano ciaranfi et alii (2001, cum bibl.). nel bacino di crosiacalopezzati sono stati studiati i terrazzi marini legati al sollevamento dell’area (carobene, 2003), mentre lo studio del substrato è ancora in corso. il rinvenimento di un livello cineritico (“cinerite di calopezzati”) nelle argille del substrato, e la sua datazione con il metodo delle tracce di fissione, ha tuttavia permesso di effettuare considerazioni sul tasso di sedimentazione e, quindi, di avanzare ipotesi sull’inizio della sedimentazione del corpo trasgressivo che costituisce il substrato; si è inoltre potuto definire con buona sicurezza il momento della sua emersione, l’età dei terrazzi marini e le velocità di sollevamento dell’area. la successione degli eventi è sintetizzabile nei seguenti punti: 1) abbassamento dell’area costiera (subsidenza) e inizio della sedimentazione pleistocenica. utilizzando la presenza del livello cineritico datato con le tracce di fissione, e in base allo spessore di argille sovrastanti, è stato ipotizzato un tasso medio di sedimentazione pari a 0,6 mm/a. (cap. 4.); con riferimento allo spessore calcolato del prisma sedimentario, (colonna di fig. 2) la sedimentazione avrebbe avuto inizio con la fine del pleistocene inferiore inizio pleistocene medio (fig. 9 – col. 2). poiché la sommersione è stata diacrona, il dato si riferisce al punto sulla verticale del livello cineritico datato (ciò vale anche per altre considerazioni successive). 2) sedimentazione e oscillazioni eustatiche. la sedimentazione è cessata con la fine del mis 9 (280.000 anni fa) (vedi paragr. 4.1 e fig. 9 – col. 2). durante la deposizione del corpo sedimentario costituente il substrato pleistocenico dell’area, il livello del mare ha subito importanti e numerose oscillazioni glacioeustatiche, per cui il corpo è in realtà una somma di sequenze sedimentarie legate alle trasgressioni, agli alti stazionamenti e alle regressioni. ciò è solo parzialmente visibile in fig. 2; la sedimentazione “ciclica”, legata cioè alle oscillazioni glacioeustatiche, è invece stata ben documentata a tarsia (valle 160 fig. 8 ricostruzione degli alti livelli interglaciali relativi ai mis 9 e 7, basata sulle quote attuali (tra parentesi). a) durante lo stazionamento 9.3 (330.000 anni fa), la sedimentazione argillosa sulla verticale del punto di affioramento del livello cineritico era ancora possibile. essendo lo spessore calcolato (s) di argille al di sopra della cinerite pari a circa 100 m, la sua attuale quota corrisponderebbe a 145 m (tra parentesi) che, confrontata con il valore del paleolivello del mis 9.3 (oggi alla quota di 210 m), fornisce una batimetria di 65 m (vedi paragr. 4.3). b) durante lo stazionamento 7.3 (220.000 anni fa) il mare intagliava invece il substrato argilloso al di sopra del livello cineritico; ciò ha dato origine al terrazzo del ii ordine, con margine interno (m.i.) alla quota attuale di 110 m circa (tra parentesi). nota: le paleoquote dei livelli 9 e 7 sono state considerate per semplicità uguali a quelle attuali. reconstruction of the inter-glacial high levels related to mis 9 and 7, based on the present day elevations (in brackets). a) during the 9.3 marine highstand phase (330,000 years ago), the clayey sedimentation along the vertical over the ash outcropping place was still possible. since the estimated thickness (s) of the clay deposits overhanging the ash level is around 100 m, its present day elevation should correspond to 145 m (in brackets). comparing this value with that one corresponding to the palaeo-level of mis 9.3 (nowadays at an elevation of 210 m), one can deduce a bathymetry of 65 m (see paragr. 4.3). b) on the contrary, during the 7.3 marine highstand phase (220,000 year ago), the sea incised the clayey substratum over the ash level. that arrangement originated the 2nd order of terraces, with inner margin (m.i.) at a present-day elevation of around 110 m (in brackets). n.b.: for simplicity, the palaeo-elevations of levels 9 and 7 have been considered equal to the present day elevations. g. bigazzi & l. carobene del crati – cosenza) da carobene et alii (1997). l’intera successione di tarsia è stata attribuita al pleistocene medio in base alla biostratigrafia basata su nannofossili, foraminiferi e ostracofauna. vi sono riconoscibili 5 sequenze deposizionali sovrapposte (ciclotemi); i sedimenti dell’ultima sequenza affiorano alla quota massima di 311 m; il terrazzo marino più alto che incide il corpo sedimentario ha il margine interno a 260÷270 m s.l.m. poiché la 4° sequenza è “più recente di 0,584 ma”, è molto probabile che essa appartenga al picco eustatico dello stage 13; di conseguenza, la 5° sequenza (la più alta) appartiene verosimilmente allo stage 11; il terrazzo a +260÷270 m (il primo a formarsi con l’emersione) può con molta probabilità essere attribuito allo stage 9. ciò rende la successione di tarsia perfettamente corrispondente a quella di crosia-calopezzati. 3) inizio del sollevamento tettonico. si può far coincidere con la deposizione della cinerite, per cui è collocabile circa 450.000 anni fa (fig. 6 – a e fig. 9 – col. 4). esso precede infatti l’alto eustatico del mis 11 (vedi punto successivo). 4) emersione del prisma sedimentario. ovviamente l’emersione è diacrona e procede da monte verso mare; essa si manifesta con evidenza in coincidenza dell’abbassamento eustatico successivo al picco 161 fig. 9 relazioni cronologiche conclusive tra curva isotopica (col. 1) (prell, 1986 in bradley, 1999 – fig. 6.11) e la successione pleistocenica (col. 2); le date di inizio (a) e di fine sedimentazione (c) sono state ricavate indirettamente in base alla datazione della cinerite (b); col. 3 = età dei quattro ordini di terrazzi marini; col. 4 = movimenti verticali dell’area; b indica il passaggio tra il regime di abbassamento e quello di sollevamento. a indica l’inizio della sedimentazione della successione stratigrafica considerata, ma non necessariamente l’inizio della subsidenza; tale inizio (a) è basato su una “velocità di sedimentazione” costante pari a 0,6 mm/a (paragr. 4.3.). la fine della sedimentazione (c) è direttamente legata allo sviluppo delle superfici terrazzate (fig. 8). conclusive chronological relationships between isotopic curve (col. 1) (after bradley, 1999 – fig. 6.11) and the pleistocene succession (col. 2); the ages of the onset (a) and of the end of the sedimentation (c) have been estimated based on the age determined on the ash level (b); col. 3 = age of the four orders of marine terraces; col. 4 = vertical movements of the study area; b indicates the transition from a subsidence to a uplift framework; a indicates the onset of the sedimentation of the studied stratigraphic succession, but not necessarily the onset of the subsidence phase. datazione di un livello cineritico ... interglaciale del mis 11 (fig. 9 – col. 3). e’ testimoniata dai sedimenti più alti in quota (277 m) (fig. 5). 5) sollevamento tettonico e 1° terrazzamento marino. il tasso di sollevamento diventa inizialmente forte (circa 1 mm/a); l’alto livello interglaciale successivo, attribuito al mis 9 (cap. 4) si posiziona 70-80 m più in basso, originando un ampio terrazzo, oggi ampiamente rimodellato e con margine interno a 210 m (fig. 5 e fig. 9 – col. 3). un campione di calcare algale ha fornito un’età th/u ≥ 300.000 anni (carobene, 2003). il tasso di sollevamento medio risulta di 0,62 mm/a. durante questo alto eustatico la sedimentazione argillosa prosegue al largo, contribuendo a ultimare lo spessore di argille (circa 100 m) che sovrastano il livello cineritico datato. si assume che la sedimentazione cessi con il successivo abbassamento eustatico (fig. 8 – a e b). 6) sollevamento e 2° terrazzamento marino. un importante alto livello eustatico interglaciale (mis 7) determina la formazione del terrazzo del ii ordine, oggi con margine interno a 105÷120 m (cap. 4) (fig. 9 – col. 3). il mare crea una estesa superficie di abrasione nelle argille precedentemente depostesi, sulla quale si depositano 35 m di depositi marini, riferibili ad un sistema trasgressivo e ad un sistema di alto stazionamento. il sollevamento tettonico e l’abbassamento eustatico relativo al mis 6 determinano un rapido abbandono del terrazzo. il tasso di sollevamento medio del terrazzo risulta pari a 0,56 mm/a (tab. 2). 7) sollevamento e 3° terrazzamento marino. un successivo importante picco eustatico interglaciale, corrispondente al mis 5.5, origina il terrazzo del iii ordine, con margine interno attualmente a 65÷70 m circa (fig. 9 – col. 3). sulla superficie di erosione basale, tagliata nelle argille del substrato, poggiano 25 m di sedimenti marini e continentali. il tasso di sollevamento medio è pari a 0,50 mm/a (tab. 2). 8) sollevamento e 4° terrazzamento marino. l’ultimo alto eustatico dello stadio 5 (mis 5.1) determina il terrazzo del iv ordine (fig. 9 – col. 3), minore dei precedenti per ampiezza e per spessore dei sedimenti. la quota attuale del margine interno, pari a 25÷30 m, permette di ricavare un tasso medio di sollevamento di 0,46 mm/a. la successione cronologica dei 4 ordini di terrazzi e del top dei sedimenti evidenzia un regolare andamento del sollevamento (fig. 6 – b), leggermente calante nel tempo (da 0,69 a 0,46 mm/a) (tab. 2). il dato è in buon accordo con i valori dedotti da studi a carattere generale (ciaranfi et alii, 1983), e da ricerche condotte in aree limitrofe (belluomini et alii, 1988, carobene et alii, 1997, cucci e cinti, 1998, palmentola et alii, 1990). tenendo conto delle incertezze nell’attribuzione delle età dei paleostazionamenti più alti e della loro quota originaria, è stato possibile calcolare l’intervallo di variabilità dei tassi di sollevamento riportato in fig. 7. per concludere, la successione di crosiacalopezzati, tarata mediante “la cinerite di calopezzati”, documenta la sedimentazione marina del pleistocene medio almeno fino allo stage 9; i 4 ordini di terrazzi marini rinvenuti documentano invece il sollevamento e la progressiva emersione dell’area. ringraziamenti ricerca finanziata con fondi del progetto di ateneo 2001, università di genova (responsabile luigi carobene). si ringrazia il prof. francesco massari (università di padova) per gli utili suggerimenti. un ringraziamento va al sig. pio novelli (università di pisa) per l’accurata preparazione dei campioni destinati all’analisi con il metodo delle tracce di fissione e al dott. cristiano queirolo (università di genova) per il supporto tecnico nell’informatizzazione dei dati. un grazie infine al prof. neri ciaranfi per la rigorosa revisione. bibliografia citata aharon p. & chappell j. 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(1988) chronology of the pleistocene oxygen isotope record: 0-1.88 m/y. b.p. palaeogeogr., palaeoclimat., palaeoecol., 64, 221-240. williams m., dunkerley d., de deckker p., kershaw p. & chappell j. (1998) quaternary environments. 329 pp., arnold, london. winograd i.j., landwehr j.m., ludwig k.r., coplen t.b. & riggs a.c. (1997) duration and structure of the past four interglaciations. quatern. res., 48, 141-154. 163 ms. ricevuto il 1° giugno 2004 testo definitivo ricevuto il 25 ottobre 2004 ms. received: june 1, 2004 final text received: october 25, 2004. datazione di un livello cineritico ... imp.ravazzi aann oovveerrvviieeww ooff tthhee qquuaatteerrnnaarryy ccoonnttiinneennttaall ssttrraattiiggrraapphhiicc uunniittss bbaasseedd oonn bbiioollooggiiccaall aanndd cclliimmaattiicc eevveennttss iinn iittaallyy cceessaarree rraavvaazzzzii c.n.r. istituto per la dinamica dei processi ambientali, milano (e-mail: cesare.ravazzi@idpa.cnr.it) abstract a short review about quaternary continental stratigraphic units based on biological and climatic events is provided, with several examples taken from italy. the potential of biochronological and biostratigraphical units is discussed. the suitability of climate events and of composite regional units in continental stratigraphy is also stressed, although a consistent definition and formal status of the latter units are not yet available. riassunto le unità stratigrafiche basate su eventi biologici e climatici sono di largo uso nel quaternario continentale, ma il loro status non è ben definito da accordi internazionali. nel presente lavoro si evidenzia il significato e l’utilità delle unità biocronologiche, biostratigrafiche, climatostratigrafiche e cronostratigrafiche e si auspica che venga mantenuta una rigorosa distinzione nel loro impiego, prendendo spunto da vari esempi in italia. viene posto l’accento sull’indipendenza delle unità biocronologiche continentali dalle biozone stratigrafiche. queste ultime sono applicabili alla distribuzione stratigrafica di microfossili (polline, diatomee) e di piccoli invertebrati, ma non è il caso dei grossi mammiferi. le unità climatostratigrafiche riguardano sia eventi a scala globale, sia regionale o locale; in ogni caso sono diacroniche e non danno luogo a correlazioni di significato strettamente cronostratigrafico. la mancanza di una chiara distinzione tra unità biostratigrafiche e climatostratigrafiche ha creato confusione nella terminologia riguardante la parte terminale del pleistocene superiore e dell’olocene. il significato delle unità in uso in questo intervallo viene discusso in un’apposita tabella. viene infine considerata la natura composita di alcune unità in uso nel quaternario continentale a scala regionale in europa occidentale, le quali risultano dalla combinazione di tutti i dati disponibili di interesse stratigrafico e cronologico. l’impiego con un significato cronostratigrafico di tali unità non dovrebbe essere confuso con la loro natura e definizione. key words: quaternary biostratigraphy, biochronology, pollen zonation, climatostratigraphy. parole chiave: biostratigrafia, quaternario, biocronologia, zonazione pollinica, climatostratigrafia. il quaternario italian journal of quaternary sciences 1166(1bis), 2003, 11-18 11.. iinnttrroodduuccttiioonn reconstructing the quaternary stratigraphy in continental environments is a difficult task because of the low degree of succession continuity and of the scattered paleontological documentation. although biological and climatic events help understanding sedimentary sequences and mapped geological units, the usage of biochronology, biostratigraphy, climatostratigraphy and composite regional stratigraphy is still limited. this paper provides a brief review to the potential of these units, with several examples from italy. a late pleistocene and holocene chronoand climatostratigraphic subdivision of continental italy and part of europe is also presented. 22.. bbiioocchhrroonnoollooggyy,, bbiioocchhrroonnoossttrraattii-ggrraapphhyy aanndd bbiioossttrraattiiggrraapphhyy fossiliferous continental deposits formed in a regime of virtually continuous sedimentation can be found in deep lacustrine environments, but they record relatively short time periods (103 – 104 years) compared to marine successions. this obstacle may be partially overcome by applying biochronological criteria. biochronology is the subdivision of geological time by means of biological events, i.e. the evolution of the organisms with respect to time and other paleobiological events, which do not imply consideration of the stratigraphic relationships among the rocks in which the fossils are included (berggren & van couvering, 1978; raffi & serpagli, 1993, tab. 1). biochrons can be defined thanks to the theoretical base provided by irreversible organic evolution, and by other paleobiological events (e.g. immigration, dispersal, emigration, and extinction). however, often the continental faunal units used in italy miss a reference to any body of rocks, or, in other terms, body of rocks including faunal assemblages have been not preserved after the fossil collection. in these conditions, it may be impossible to describe biostratigraphic units, and only biochronologic or biochronostratigraphic unit can be conceived1 . the concepts of mammal continental biochronology were developed by lindsay and tedford (1990), fejfar & heinrich (1990) and walsh (1998). a quaternary biochronological scheme of the italian mammal and mollusc faunal complexes is well established (gliozzi et al., 1997; kotzakis, this issue). the interpretational approach provided by biochronology is also inherent the characterization of floristic com1 bbiioocchhrroonnoossttrraattiiggrraapphhiicc uunniittss are “the sets of rock formed during biochrons, without reference to any particular stratigraphic section” (walsh, 1998). bbiioossttrraattiiggrraapphhiicc uunniittss are instead “bodies of rock strata that are defined or characterized on the basis of their contained fossils” (ics, 1994, p. 53). 12 c. ravazzi table 1 the stratigraphic categories currently used in quaternary sciences. the table includes units formally defined in the international code of stratigraphy (salvador, 1994) and other categories that, despite not yet formally defined by ics, are of importance for quaternary stratigraphy and are of common usage. the relevant references (only for units not included in ics) are here reported: 1 cushing, 1967; birks & gordon, 1985; tzedakis, 1994; 2 kerney et al., 1980; 3 de giuli et al., 1986; 4 fejfar & heinrich, 1990; lindsay & tedford, 1990; walsh, 1998; 5 de giuli et al., 1983; 6 mai & walther, 1978; 7 lowe & walker, 1997; 8 walker et al., 1999; 9 johnson et al., 1997; 10 zagwijn, 1992. the term “composite regional units” is used to refer “regional stages” of the dutch stratigraphy. this terminological problem is discussed in the text. ssuummmmaarryy ooff ccaatteeggoorriieess uusseedd iinn tthhee ccoonnttiinneennttaall qquuaatteerrnnaarryy ssttrraattiiggrraapphhyy (non-referred units are from salvador, 1994) (*) mappable units; (+) stratotype sections applicable 11.. cchhrroonnoollooggyy 22.. rroocckk pprrooppeerrttiieess 33.. ffoossssiill ccoonntteenntt cchhrroonnoossttrraattiiggrraapphhyy ((**)) ((++)) lliitthhoossttrraattiiggrraapphhyy ((**)) ((++)) bbiioossttrraattiiggrraapphhyy ((++)) eonothem group pollen superzone1 erathem formation pollen zone system membre other biozones and ecozones2 series stratum (based on diatoms, stage cyanobacteria, green algae, substage ppeeddoossttrraattiiggrraapphhyy ((**)) ostracods, molluscs, etc.) chronozone mmiinneerraallooggyy ((**)) ((++)) bbiioocchhrroonnoossttrraattiiggrraapphhyy eeqquuiivvaalleenntt ggeeoocchhrroonnoollooggiicc uunniittss heavy mineral assemblages aanndd bbiioocchhrroonnoollooggyy eon mmaaggnneettoossttrraattiiggrraapphhyy ((++)) era (cenozoic) polarity zone biochronological events3 period (quaternary) land mammal ages4 epoch (pleistocene) iissoottooppiicc ssttrraattiiggrraapphhyy ((++)) faunal units5 age δ18o stages from sea records local faunas5 subage (mis = marine isotopic stages) floral complexes6 chron δ18o from polar ice (gs / gi) local floras6 termination human cultural chronology cchheemmiioossttrraattiiggrraapphhyy 44.. ccoommppoossiittee aanndd iinntteerrpprreettaattiioonnaall ssttrraattiiggrraapphhiicc ccaatteeggoorriieess ((oonnllyy 44..bb aanndd 44..ee aarree ddeettaaiilleedd hheerree)) 44..aa.. ccyycclloossttrraattiiggrraapphhyy ((**)) ((++)) 44..bb.. eevveenntt ddiiaacchhrroonniicc ssttrraattiiggrraapphhyy event (whittaker et al., 1991) bbaasseedd oonn cclliimmaattiicc eevveennttss iinnffeerrrreedd bbyy ssttrraattiiggrraapphhiicc ppaatttteerrnn [[cclliimmaattoossttrraattiiggrraapphhyy ((++))]] aanndd ootthheerr eevveennttss:: geologic-climatic (geoclimatic) units7 global interglacial, global glaciation7 stadial, interstadial episodes and sub-episodes (mostly at regional scale) gi/gs (greenland stadial / interstadial episodes and subepisodes)8 bbaasseedd oonn bboouunnddaarriieess ooff rreeffeerreenntt ddeeppoossiittss ffrroomm wwhheerree eevveennttss aarree iinnffeerrrreedd ((**)) rock diachronic event units9 episode subepisode phase 44..cc.. uunnccoonnffoorrmmiittyy bboouunnddeedd ssttrraattiiggrraapphhiicc uunniittss 44..dd.. sseeqquueennccee ssttrraattiiggrraapphhyy 44..ee.. rreeggiioonnaall ccoommppoossiittee ssttrraattiiggrraapphhyy ((**)) ((++)) ccoommppoossiittee rreeggiioonnaall ssttaaggee1100 a combination of the above mentioned properties (e.g. paleomagnetic polarity, lithostratigraphy, susceptibility log, radiometric dating, pollen stages succession, climatostratigraphic succession) considered at regional scale and boundary-defined. plexes, first defined in the lowlands of germany (mai & walther, 1978) and recently applied to the continental carpofloral assemblages of the western po plain (martinetto, 1995). considering the italian continental paleobiological record, only the distribution of some microfossil, e.g. pollen and diatoms, and of small invertebrates (ostracods, chironomids), matches the requirements to establish biostratigraphic units. there are only a few examples of continental biostratigraphy in italy. several paleoecological investigations have proposed a local biozonation, based on the succession of biotic assemblages at a single lacustrine or palustrine small basin. so far there is detailed local biozonation back to 14 kyr bp at the southern alpine foothill (schneider, 1978; wick, 1996), in central alps (tinner, 1998; pini, 2002), in the central italian peninsula (lowe, 1992; brugiapaglia & de beaulieu, 1995; lowe et al., 1996) and in central sicily (sadori & narcisi, 2001). the pollen zonation from the monticchio maar lake (southern apennines) and from the latium extends to the last 100 kyr bp (magri, 1999; magri & sadori, 1999; allen & huntley, 2000). one site is zoned back to about 250 kyr bp (valle di castiglione: follieri et al., 1988). detailed pollen zonation is also available for the middle pleistocene lacustrine record of vallo di diano (russo ermolli, 1994), from part of the early pleistocene lacustrine sequence of leffe in the lombardian pre-alps (ravazzi & rossignol strick, 1995; ravazzi & moscariello, 1998) and from the late early pleistocene colle curti and cesi basin sequence (bertini, 2000). the development of regional pollen zones applies to biogeographically homogeneous regions, which are provided with several pollen records. although each site is characterized by a peculiar vegetation development (shown by the succession of local pollen zones spanning an entire warm or cold phase: this is the concept of pollen assemblage superzone, proposed by tzedakis, 1994), a comparative inspection of pollen curves shows that different sites have in common a similar background pollen, after eliminating local plants from the pollen sum. this is the case of latium maar lakes, where the main changes observed in the five long pollen records available have been correlated (follieri et al., 1989). a quantitative analysis by numerical methods (sugita 1994) can help defining the biogeographical limits of a regional pollen zone. regional pollen zones are commonly time-transgressive (lowe & walker, 1997); this is partially due to migration time lags (102 kilometers per 103 years). however, once the migration pattern is known and well dated, the time of immigration and / or expansion at a given site by a good pollen producer may be a precise biostratigraphic marker (e.g. the holocene migration history of picea, ravazzi, 2002). 33.. eevveenntt ssttrraattiiggrraapphhyy aanndd cclliimmaattoossttrraattiiggrraapphhyy climatostratigraphy (the modern development of geoclimatic stratigraphy) is a type of “event diachronic” stratigraphy based on interpreted climate features from evidence in the rock/sediment record (see lowe & walker, 1997). events are short-term phenomena that leave some trace in the geological record (e.g. volcanic eruptions, sea level changes, etc.). as noted by walker et al. (1999), "it is primarily the events and not the boundaries between the events that are specifically designated" (by climatostratigraphic inferences). furthermore, climatostratigraphy "acknowledges the fact that the stratigraphic boundaries marking the onset and ending of a climatic event may well be diachronous (.....)". climatostratigraphic units are best derived by a combi13an overview of the quaternary ... nation of different stratigraphical categories, such as lithological, biological, isotopic (walker et al., 1999), and ubsu units used in sequence stratigraphy (miall, 1997). whenever emphasis is on globally recognized climatic-events, climatostratigraphic subdivisions may concern the whole earth, such as global glaciations, interglacials and the interglacial-glacial cycle. local climatostratigraphic units may represent events recorded by relevant deposits, for instance at the scale of a basin catchment (e.g. high-intensity rain triggering catastrophic floods), or of a climatic province (e.g. lake level changes, etc.), or of a whole mountain chain (e.g. local glaciation). climatic events which occurred at regional scale, together with other derivate types of event stratigraphic units, such as volcanic eruptions, are widely used in italy (narcisi & vezzoli, 1999) and provide a powerful method for marine / continental correlations. for instance, the beginning of the late glacial interstadial (tab. 2) has been recognized in maar deposits from the italian peninsula as well as in marine sediments from the adriatic sea. inter-regional and marine / continental correlation has been possible thanks to the background arboreal pollen signal, which shows an abrupt shift at 12.4 ka 14c bp (lowe et al., 1996). this pollen signal has been compared with other paleoclimatic proxies (geochemistry, rock-magnetism, isotopes, diatoms, other algae, invertebrate fossil remains), for a multidisciplinary evaluation of the climatic event triggering the observed physical and biological changes (guilizzoni & oldfield, 1996). the climatic events are commonly very close to the boundaries of the biostratigraphic subdivisions from where events are inferred. the international stratigraphic guide (salvador, 1994) misses to consider climatostratigraphy as a basic stratigraphic category of common use. the present author believes that a rigorous distinction between biostratigraphic and climatostratigraphic units needs to be maintained (on this problem see turner, 2002 discussing the status of the eemian interglacial). an effort to add precision to the terminology used in different branches of stratigraphy is made in tab. 2 and 3. 44.. ccoommppoossiittee rreeggiioonnaall uunniittss several quaternary stratigraphers from central europe acknowledges the use of continental “stages” (gibbard et al., 1991; zagwijn, 1998). from the paleoclimatological point of view, some of them are “complex stages” (zagwijn, 1992, p. 585). these units (tab. 1b) derive from a combination of all available stratigraphic (lithologic, ubsu, magnetic, biologic and climatic) and chronological (geocronometric, biochronological) data. the paleoclimatic complexity of such units is not the only defining characteristics, and therefore i would suggest to refer them as composite regional units. because they are based on diachronic-type stratigraphic units (such as climatoor biostratigraphic units) they are not chronostratigraphic units (not a stage by definition). however, composite regional units are also intended to provide a chronostratigraphical reference for biogeographically circumstancied regions, hence the term “stage” (which implies a chronostratigraphic unit) has been used with reference to rocks formed during the relevant time interval (gibbard et al., 1991; zagwijn, 14 c. ravazzi tab. 2 framework of late pleistocene chronologic and climatostratigraphic reference units used in western-central europe (column climatostratigraphy dealing with the alps only) and detail of local units applicable to selected regions. algm = alpine last glacial maximum. the age of northern germany and netherlands interstadials (oerel, glinde, moershoofd, hengelo and denekamp) is from behre & van der plicht (1992), calibrated with the method by bard et al. (1998). alpine deglaciation and the late-glacial interstadial may be partially coeval. the term neoglaciation is from porter & denton (1967). 1992). the usage of a composite regional stratigraphy in continental regions is not formalized by the international stratigraphic code currently in use (salvador, 1994), and its chronostratigraphic value is still a matter of debate (gibbard & west, 2000). composite regional units are also characterized by a 15an overview of the quaternary ... tab. 3 late glacial and holocene chronostratigraphy / geochronology and climatostratigraphic units (from orombelli & ravazzi, 1996, modified and updated). chronozones are framed by conventional 14c ages bp. the late glacial is subdivided by using climatostratigraphic criteria. this is because the late glacial is characterized by sharp climatic changes which have been recognized either in terrestrial biological records, either in ice and in marine records, but these climatostratigraphic transitions do not fit the boundaries of the relevant chronozones proposed by mangerud et al. (1974). consequently, these late glacial chronozones miss any practical interest. holocene chronozones are provisory maintained here, waiting for further international agreements. note that the last glacial maximum in the italian alps ends about 15 ka 14c bp, well before than in central and northern europe. the earliest interval of the alpine late glacial, or, in other terms, the time interval between the beginning of the alpine deglaciation and the late glacial interstadial is poorly defined in stratigraphic terms. (* 1) the subdivisions early, middle and late holocene are informal, with boundaries at ca 7000 and 3000 bp. (* 2) the calendar 14c age bp has been calibrated with the program calib 4.0 elaborated by stuiver and reimer (1998). the calibrated ages are reported as one sigma time intervals obtained using a standard deviation of ± 50 yr on the conventional age. (* 3) the framing of the “holocene thermal optimum” between about 9 and 5 kyr 14c bp is based on: i) the δ18o curve from the renland ice core (larsen et al., 1995); ii) the record of alpine glacier contraction during the early-middle holocene (hormes et al., 2001); iii) the paleoecological record of treeline oscillation in the alps (wick & tinner, 1997). this concept of the holocene thermal optimum is different from the hypsithermal (porter, 1981), used in a previous version of this scheme (orombelli & ravazzi, 1996). (* 4) the younger dryas is here taken as a climatostratigraphic unit. l.i.a. = little ice age. dashed lines indicate large-scale diachronic boundaries. (* 5) a substantial increase of climatic humidity in the alps does not fit this boreal / atlantic chronozone boundary but occurred later, about 7.3 ka 14c bp, i.e. about 8.2 ka cal bp (tinner & lotter, 2001; pini, 2002). stratotype. for instance, an eemian stratotype was provided by van der heide and zagwijn (1967); see turner (2002), for a review. moreover, reference sections and boundaries or boreholes may be designated, such as the amsterdam borehole for the eemian (van leeuwen et al., 2000). the designation of stratotypes and / or reference sections for continental units is mentioned by the international stratigraphic code currently in use (ics, 1994, p. 77). the present author believes reference sections to be necessary for any further study. this procedure is expecially fruitful in case that bioprovinces are partially cohincident with sedimentary basins, a situation which may apply to the quaternary evolution of the apenninic intermontane basins and of the po plain. 16 c. ravazzi unfortunately, so far there are no proposals for composite regional units in italy. 55.. ccoonncclluussiioonn a consistent definition and formal status of continental stratigraphic units based on biological and climatic events is not yet available in the official agreements of iugs and inqua. this paper has emphasized the importance to maintain rigorous distinction among biochronologic, biostratigraphic, climatostratigraphic and chronostratigraphic units. the marked geological, environmental and climatic diversity affecting both the alpine and the mediterranean regions hampers correlation based on biological and climatic events. hope is placed in a multidisciplinary characterization of bioprovinces and of their relation to the major sedimentary archives of past environmental change. aacckknnoowwlleeddggeemmeennttss the comments by remo bertoldi (univ. of parma), maria rita palombo (univ. la sapienza, rome), benedetto sala (univ. of ferrara), danilo torre (univ. of firenze) and charles turner (open university, uk) helped to improve an earlier version of the manuscript. however, the author is the only responsible for the present paper. rreeffeerreenncceess allen j.r.m. & huntley b., 2000 weichselian palynological records from southern europe: correlation and chronology. quat. int., 7733//7744, 111-125. bard e., arnold m., hamelin b., tisnerat-laborde n., cabioch g., 1998 radiocarbon calibration by means of mass spectrometric 230th/234u and 14c ages of corals: an updated database including samples from barbados, mururoa and tahiti. radiocarbon, 40 (3), 1085-1092. behre k.-e. & van der plicht j., 1992 towards an absolute chronology for the last glacial period in europe: radiocarbon dates from oerel, northern germany. veget hist archaeobot, 11, 111-117. berggren w.a. & van couvering j.a., 1978 biochronology. in: cohee g.v., m.f. glaessner, & h.d. hedberg (eds.), contribution to the geologic time scale. american association of petroleum geologists bulletin, 5500, 1487-1500. bertini a., 2000 pollen record from colle curti and cesi: early and middle pleistocene mammal sites in the umbro-marchean apennine mountains (central italy). journal quat. sci., 1155 (8), 825-840. birks h.j.b. & gordon a.d., 1985 numerical methods in quaternary pollen analysis. academic press, london. brugiapaglia e., de beaulieu j.l., 1995 etude de la dynamique végétale tardiglaciaire et holocène en italie centrale: le marais de colfiorito (ombrie). comptes rendu academie science paris, 332211, 617-622. de giuli c., ficcarelli g., mazza p., torre d., 1983 confronto tra successioni marine e continentali del pliocene e pleistocene inferiore in italia e nell'area mediterranea. boll. soc. paleont. ital., 2222 (3), 323328. fejfar o. & heinrich w.-d., 1990 muroid rodent biochronology of the neogene and quaternary in europe. in: lindsay e.h., fahlbusch v., mein p. 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(it issn 0394-3356, 2005). il terremoto del 1117 può essere considerato l’evento distruttivo di riferimento per la storia sismica di una vasta parte della pianura padana. tuttavia, a causa della lontananza temporale delle fonti e della oggettiva complessità dell’evento (terremoto multiplo), la sua attuale ubicazione epicentrale (verona) non appare rappresentativa della distribuzione degli effetti. sulla base del riesame completo delle fonti primarie conosciute e di quelle poche non note nei precedenti studi, nonché da evidenze di carattere archeosismologico, viene proposto un quadro indiziario degli effetti che, confrontato con le possibili strutture sismogenetiche sepolte della pianura padana, permette di ipotizzare l’esistenza di un secondo epicentro in area basso-padana, verosimilmente ubicato nel cremonese. abstract: p. galli, the earthquakes of january 1117 in northern italy. hypothesis for an epicentre in the southern po plain (cremona), (it issn 0394-3356, 2005). the 1117 earthquake is probably the strongest event which occurred in northern italy during the historical period. although its eco, and perhaps its effects were felt in a vast area of central and southern europe (i.e., from reims to montecassino) its epicenter is still uncertain and strongly debated, and it is presently placed near verona by the italian seismic catalogue (gruppo di lavoro cpti, 1999). actually, we know that it was a long seismic sequence, characterized by more than one mainshock, with damage areas in the adige valley (south of trento), in the verona territory, and in the area nw and se of cremona (enel, 1986; magri e molin, 1986; boschi et al., 1995; galadini et al., 2001b). damage were also reported in a village near august (germany) and pisa, being related to earthquakes which occurred by chance in the same days, but without any possible seismotectonic significance with respect to the earthquake cited universally by the historical source as happened in “longobardia” (the land of northern italy ruled by longobards during middle ages). in northern italy, the damaged localities explicitly quoted by the local synchronous sources (excluding those mentioned repetitively in transalpine chronicles: verona …. similiter parma et in venetia) are only verona, ronco all’adige (a small village se to verona) and cremona, while three memorial stones witness effects in padua, costozza and nonantola (villages near padua and modena, respectively). a strong effect is also recorded in milan and its province. from the seismotectonic point of view, galadini et al. (2002) placed the source of the 1117 earthquake on the so-called thienebassano thrust, which is located between 110-130 km away from cremona, along the southalpine front. as for the effect in cremona, new archaeoseismic data deduced from archaeological excavation carried out in the past years in the cathedral confirm and enrich the frame depicted by the synchronous sources (collapse of the new (?) church under construction during the 1117 earthquake, burying of the remains of the patron saint himerius under the ruins, and their recovery only twelve years later). moreover, this data seems to demonstrate that the current cathedral was entirely rebuilt following the earthquake, none of the wall or structures in fieri during the 1117 having been saved after the collapse. the original design of the cathedral started in 1107 was changed, and only few sculptures and architectural elements in situ before the earthquake were re-employed afterwards. based on the above, it is very difficult that damage and collapses in places located up to 100 km away from each other may be accounted for only one seismic source. considering the existence of more than one mainshock between 2-3-4 january (as reported by the historical sources), the event which hit southern lombardy and neighboring places before 5 p.m. (local time) of january 3 could be related to a local seismogenic structure, and not to the fault which caused damage in the same hours/days in the verona-padua area (i.e., the mentioned thiene-bassano thrust). this structure could be identified with one of the thrusts existing along the buried front of the apennine chain which show traces of recent tectonic activity, as the one affecting the buried piadena anticline, just under the province of cremona. parole chiave: archeosismologia, sismicità, tettonica attiva, italia settentrionale. keywords: archaeoseismology, seismicity, active tectonics, northern italy. il quaternario italian journal of quaternary sciences 18(2), 2005 87-100 1. introduzione il terremoto del gennaio 1117 è, senz’altro, uno dei più forti e poco compresi eventi sismici dell’italia settentrionale. mentre la sua eco, ma forse i suoi stessi effetti, si sono risentiti in una vasta area dell’europa centro meridionale, da reims a montecassino, la sua area epicentrale non è ancora univocamente riconosciuta, anche se il suo epicentro è posto dai cataloghi sismici italiani nei pressi di verona (p.e., gruppo di lavoro cpti, 1999). in realtà, sappiamo che si trattò di una lunga e complessa sequenza sismica, caratterizzata, presumibilmente, da più mainshocks, con probabili aree di danno nella valle tridentina (la val d’adige da nord di trento a nord di verona), nel veronese e nell’area tra cremona e nonantola (enel, 1986; magri e molin, 1986; boschi et al., 1995; galadini et al., 2001b). danni sono anche segnalati in un villaggio presso augusta (heirenbuch, germania) ed a pisa1, certamente relativi 1 la notizia è in guido pisano, biblioteca apostolica vaticana, cod. vat. lat. n. 11564, c. 91. (vedi scalia, 1963). 88 p. galli ad eventi sismici casualmente avvenuti negli stessi giorni, ma che nulla hanno a che fare, dal punto di vista sismotettonico, col terremoto in longobardia citato universalmente dalle fonti. a nord di pisa, le località italiane danneggiate citate esplicitamente dalle fonti sincrone locali, a parte quelle ricorrenti in modo litanico nelle cronache transalpine (verona … similiter in parma et in venetia), sono solo verona (annales veronenses2; donazione di decima3, ed altri: cfr. in enel, 1986), ronco all’adige4 (vedi kehr, 1961) e cremona (vedi oltre), mentre tre lapidi attesterebbero danni a padova (dispersa5), a nonantola (di controversa lettura 6) e/o un forte risentimento a costozza7 (fig. 1a). per milano, fonti coeve attestano un forte risentimento in città e nella provincia (beroldus, xii sec.). sulla cronologia delle diverse scosse non ci sono certezze, sebbene le notizie convergono quasi tutte sul 2-3-4 gennaio (molte fonti parlano dell’octava sancti johannis evangelistae8 oppure iii nonas ianuarius9). per quanto attiene l’orario, alcune fonti recitano “una volta di giorno ed una di notte”, altre “due volte tra giorno e notte”; oppure “al canto del gallo ed all’ora nona”, “dopo il terzo canto del gallo e quasi alla decima ora”, “prima del tramonto”, “all’ora vespertina”, “dopo i vespri, a cena”. in particolare, le fonti di area lombarda (cremona e milano), parrebbero collocare il terremoto (cioè la scossa principale “locale”) mercoledì 3 gennaio, all’ora del vespero, cioè prima delle 17 ora locale10, mentre a pisa l’evento locale11 è riferito a giovedì 4 gennaio alle 16:15 (15:15 gmt; hora xi) ed una forte scossa, forse il risentimento di un forte evento lontano, nella notte precedente. nel complesso, è probabile che essendo le aree di principale danneggiamento più d’una – e, riassumendole, una presso augusta, una nell’area trentinoveneta, una in quella lombardo-emiliana ed una in quella pisana le diverse cronache di regioni distanti12 – attingendo anche l’una dall’altra abbiano confuso e/o unificato gli orari delle eventuali diverse scosse. di sicuro l’impatto del terremoto fu talmente forte che l’evento rimase nella memoria delle persone per molti anni, almeno in tutta l’area lombardo-veneta-emiliana. lo testimoniano numerosi documenti notarili nei quali il terremoto è usato come termine cronologico di riferimento per fatti avvenuti a distanza anche di settant’anni13. in questo lavoro, a seguito della disamina delle fonti primarie relative a cremona (e subordinatamente, ad altre città emiliane) ed unitamente alla presentazione di indizi di carattere archeosismico raccolti nell’area della sua cattedrale, viene delineato un quadro di danneggiamento centrato nella bassa padana orientale. il confronto poi con le possibili strutture sismogenetiche desumibili dalla letteratura ha permesso di formulare nuove ipotesi concernenti l’epicentro di uno dei mainshock della sequenza del 1117. non si nasconde il carattere in parte speculativo e, perché no, provocativo di questa nota; d'altronde, essa è stata anche concepita nella vaghezza che certi temi di ricerca, quale l’analisi in chiave archeosismologica degli edifici medievali padani, possano concorrere in futuro ad un quadro più convincente di questo terremoto. 2. il terremoto a cremona 2.1 le fonti. come detto, cremona è una delle poche località per le quali ci siano giunte notizie contemporanee certe relative al danneggiamento causato dal terremoto. la più sicura è quella contenuta nei cronica del cremonese sicardus (vescovo tra il 1185 e il 1215) che, per la vicinanza di luogo e di tempo, sicuramente potè attingere a notizie di prima mano. essa ci dice che nell’ “anno domini millesimo cxvi [per 1117], terre motus magnus in ianuario fuit, 2 vi si ricorda in data 12 gennaio 1117 la consacrazione della chiesa della santa trinità che, evidentemente, non era stata danneggiata e, a seguire, quasi en passant, “hoc anno multes turres et innumerabilia edificia propter terremotum per longobardiam et alias terras corruerunt …. [a] terremotus maximus fuit, in quo etiam magnam pars arene cecidit”. 3 si riporta la rinuncia da parte del visconte ridolfo ad una decima in data 24 gennaio 1117 “usque ad diem quo civitas verona terremotu tam grandi exterminata est”. 4 la chiesa di s. maria a “runco” è detta “terrae motus eversa” nell’anno 1117. 5 ricordata da scardeone (1560) nella chiesa di santa giustina: “anno domini mcxxiiii indictione ii / arte magistrali macilli me struxit ab imo / clerus: terrae primo motus subvertit ab imo”. 6 l’iscrizione, scolpita sull’architrave del portale in facciata, adattandosi agli spazi scanditi dalla frattura che attraversa la pietra, recita: “silvestri celsi ceciderunt culmina templi mille redemptoris lapsis vertigine solis / anni centenis septem nec non quoque denis quod refici magnos cepit post quattuor annos”. il senso, potrebbe essere che “negli anni 1117 del redentore caddero i tetti del tempio dell’eccelso silvestro, squassato il “terreno per il moto vorticoso”, e parimenti prese ad essere rifatto dopo quattro anni”. oppure, come in enel (1986), che “le cime del grande tempio di silvestro caddero dopo che le “rivoluzioni del sole” nel 1117 avevano segnato molti anni da cristo. la ricostruzione fu iniziata dopo quattro anni”. in questa seconda lettura, il terremoto non viene evocato come causa del crollo. 7 alla base del campanile di san mauro: “t[empore] teremoti mcxvii / mccxxiii t[em]p[ore] teremoti / mcccxliii teremoti”. 8 otto giorni dal 27 dicembre, san giovanni evangelista e cioè il 3 gennaio. 9 tre giorni dalle nonae, invero dal 5 e quindi il 3 gennaio; altre fonti riportano iv nonas, cioè il 2 gennaio od il giorno prima delle nonae, cioè 4 gennaio. 10 il tramonto del sole i primi di gennaio in lombardia è verso le 16.50. in gruppo di lavoro cpti, 1999, il terremoto è riportato, invece, alle 13.00 gmt. 11 che, come detto, nulla può avere a che fare col terremoto in longobardia. 12 se ne veda una valida rappresentazione in enel, 1986. 13 oltre ai documenti relativi al veronese ed al piacentino riportati in enel (1986) ed a quelli noti per l’area tra mantova e rovigo (in galadini et al., 2001) se ne sono rintracciati diversi altri per l’area bresciana sul tenore di: “quando fuit terremotus”, “de teramotu maiori”, “a tempore terremotus”, “per terremotum”, “ante terremotum”, tutti datati tra il 1163 ed il 1189 (vedi codice diplomatico bresciano, 1, ed. di e. barbieri, e. cau in: codice diplomatico della lombardia medievale). 89i terremoti del gennaio 1117 ... fig. 1 a, località danneggiate dal terremoto del 1117 così come desunte l i m i t a t a m e n t e alle fonti primarie (area italiana settentrionale). b, quadro sis m o t e t t o n i c o della pianura padana e zone limitrofe. le strutture in grassetto sono relative al dominio alpino. sono stati evidenziati i soli box sismogenetici (proiezione in superficie del piano di faglia) dei terremoti del 1117 e 1695 sul fronte sudalpino (da g a l a d i n i et al., 2002); quello in prossimità di cremona è ipotizzato in questo lavoro. i paleoterremoti sono tratti da galadini e galli (1999) e da galadini et al. (2001a). a, localities damaged by the 1117 earthquake as deduced from primary historical sources. b, seismotectonic sketch of the po plain (bold lines are alpine t h r u s t s ) . seismogenetic box (surface projection of the fault plane) of the 1117 and 1695 earthquakes after g a l a d i n i et al . (2002); the one near cremona has been hypothesized in this paper. paleoearthquakes after g a l a d i n i and galli (1999) and galadini et al (2001a). 90 propter quem maior cremonensis ecclesia corruit, et corpus confessoris ymerii diu latuit sub ruina…lotharii temporibus obertus cremonae fuit episcopus, qui sancti himerii, quod diu latuerat, corpus invenit, & anno domini mcxxix in scrineo serrato recondidit”. altra notizia è contenuta nella cronichella cremonese, fonte del xiii secolo, che dice per l’anno 1116, invero 1117: “tertis nonas januarius terremotus magnus fuit per quem major cremonae ecclesiae corruit, et corpus sci himerij diu labuit [sic] sub ruina”. quindi, per l’anno 1129: “obertus fuit episc. cremonae qui corpus sci himeriis quod diu labuit [sic] propter ruinam invenit et in scrineo ferrato [sic] recondidit”. ancora, sempre del xiii secolo, il chronicon cremonense: “quando fuit terraemotus, mcxvi [per 1117] in octava sancti johannis evangelistae hora vesperum … mcxxix … et eodem anno inventum fuit corpus sancti himerii in mense madii”. infine, alberto di bezano, abate di san lorenzo a cremona, nel xiv secolo: “anno domini mcxvi [per 1117], indictione x, iii nonarum ian. terremotus magnus fuit, propter quem maior cremonensis ecclesia corruit, et corpus confessoris ymerii diu latuit sub ruina”. queste notizie, più o meno ripetendosi l’un l’altra, ci dicono che in occasione del terremoto, avvenuto il 3 gennaio prima delle 17.00 (ora locale), la cattedrale di cremona crollò, ed il corpo del santo protettore imerio rimase a lungo sotto le macerie, sino a quando fu ritrovato nel maggio 1129 ed il vescovo oberto lo pose al sicuro in uno scrigno. 2.2 indizi archeosismici in cattedrale. assumendo dunque che la cattedrale, in toto od in parte, crollò, è possibile oggi trovarne dei riscontri oggettivi ovvero degli indizi archeosismici in situ? ma innanzitutto, quale cattedrale crollò? (fig. 2). notizie di una “vetus ecclesia maior sancte marie de cremona”, forse danneggiata insieme al resto della città al termine dell’assedio postole da agilulfo nell’agosto del 603 (“civitatem cremonensem…..ad solum usque destruxit”, p aolo diacono, viii sec.), contrapposta ad una “sancte marie novae de cremona”, si hanno in documenti della metà del vii secolo (codice diplomatico longobardo14). tracce della nuova (o restaurata) chiesa, cointestata a santa maria ed a santo stefano, si hanno finalmente in un diploma di lotario i, datato 84115, che richiama precedenti diplomi dei tempi di carlo magno (governo 774-814) e ludovico pio (governo 814840). la cointestazione si spiega col fatto che, probabilmente, si trattava di una “cattedrale doppia” (m irabella r oberti, 1979), le cui due aule16 erano separate dal battistero paleocristiano di recente riconosciuto negli scavi della cripta17 (vedi fig. 3). sino a prova (documentale) contraria, la costruzione di una nuova cattedrale di cremona fu intrapresa sotto il pontificato di pasquale ii nel 1107, con l’ausilio di maestranze in parte fuoriuscite dal cantiere della cattedrale di modena (il cui altare era stato consacrato l’anno precedente), in un’area, quella precedente, occupata sin dall’antichità da un grande edificio residenziale di epoca imperiale (30-40 d.c.18), e sulle rasature di preesistenti edifici di culto cristiano. questi ultimi si datano tra il iv ed il v secolo19 ed al vi-viii secolo20. la data di fondazione della cattedrale (110721) è fig. 2 a sinistra, immagine della cattedrale di cremona nella matrice di un sigillo del comune del 1249 (proprietà dell’autore). la facciata romanica è quella della ricostruzione successiva al terremoto del 1117, con ulteriori modifiche degli inizi del ‘200 (vedi in gandolfo, 2001), mentre a destra è la veduta dell’odierna facciata, dopo i rimaneggiamenti basso medievali e rinascimentali. left, the cremona cathedral on a seal matrix dated 1249. the romanesque facade is due to the rebuilding after the 1117 earthquake, modified at the beginning of the 13th cent. (gandolfo, 2001). right, present facade, after the low-middle age and renaissance “restyling”. 14 ma alcuni di questi codici, ed in particolare il complesso di cremona, sono ritenuti in parte contraffatti dal canonico dragoni tra ‘700 e ‘800. 15 praeceptum lotharii i imperatoris, 841 maggio 12, quincy; vedi codice di sicardo, xii-xiii sec., ed. di v. leoni in: codice diplomatico della lombardia medievale, viii-xii sec. 16 mirabella roberti (1979) credè di identificare una delle aule proprio con i lacerti musivi di iv-v secolo nel cortile del torrazzo e con brani di muratura paralleli al muro nord del duomo romanico. l’altra aula potrebbe identificarsi con lacerti murari e di pavimento in cocciopesto da poco scavati nel locale caldaie del duomo; l. passi pitcher, sopr. arch. reg. lombardia, comunicazione personale. 17 l. passi pitcher, comunicazione personale. vedi nota 19. 18 l. passi pitcher, comunicazione personale. 19 si tratta di un impianto battesimale ottagonale, probabilmente in fase con l’edificio mosaicato rinvenuto nel cortiletto del torrazzo (quello stesso che dovrebbe identificarsi con l’aula principale della cattedrale, i.e., santa maria) e databile ad un età non anteriore al iv secolo grazie ad un vaso a listello tardo romano rinvenuto nella preparazione del mosaico; l. passi pitcher, comunicazione personale. 20 un’aula con funzioni sacre, addossata al battistero stesso; l. passi pitcher, comunicazione personale. 21 secondo cavitelli (1588), la prima pietra fu posta il 25 agosto 1107 dal vescovo gualtiero. p. galli 91 essere murata in facciata o, secondo altri, nell’altare (puerari, 1971) o costituire il dossale della cattedra episcopale (gandolfo, 2001); invece essa è murata, anzi accantonata nella sagrestia dei canonici, ma non per caso, come vedremo in seguito. di fatto, come precedentemente ricordato, al momento del terremoto il corpo del santo protettore era custodito nella cattedrale in costruzione 22, della quale probabilmente erano già in opera e/o pronti per la posa pavimenti a mosaico, portali ed arredi scultorei diversi (vedi oltre). queste evidenze lasciano intendere che la cattedrale fosse ancora assolutamente in fieri piuttosto che, come ipotizzato da quintavalle (1982) in analogia a modena, terminata23. tuttavia, è opinione della critica, da porter (1916) a puerari (1971), che in occasione del terremoto la cattedrale di cremona fosse in avanzata fase di edificazione e che i crolli testimoniati dalle fonti contemporanee abbiano interessato parte dell’edificio (p.e. l’abside) e siano stati proprio causati dalla fragilità dell’edificio in costruzione (enel, 1986). secondo quintavalle (1973) poi, l’edificio attuale è sostanzialmente anteriore al sisma che ne provocò solo il crollo parziale della zona del tiburio. in realtà, le evidenze archeologiche recentemente messe in luce dalla soprintendenza archeologica della lombardia (in passi pitcher, 2003), qui interpretati in chiave archeosismologica, disattendono le opinioni di alcuni degli autori citati, in quanto mostrano come la chiesa attuale non è quella intrapresa nel 1107 e, come dirò, non è quella danneggiata nel 1117. nel corso di scavi eseguiti nella cripta del duomo tra il 1988 ed il 2000, sono fig. 3 ipotesi planimetrica dei diversi complessi episcopali succedutesi prima e dopo il terremoto del 1117. la base in grisé rappresenta l’attuale cattedrale romanica (mod. da puerari, 1971). a tratto pieno, a nord, la basilica paleocristiana di santa maria con lacerti murari e pavimentali (1); a sud la seconda aula paleocristiana di santo stefano, con avanzi dell’abside (2); al centro il battistero. tutto il primo complesso a doppie chiese è databile, su basi archeologiche, al iv-v secolo (vedi testo) e potrebbe essere stato più o meno danneggiato e ristrutturato a seguito dell’assedio di agilulfo nel 603 (vedi interventi databili al vi-viii secolo al battistero). a tratteggio, al centro, la nuova cattedrale di santa maria, cominciata e solo in parte realizzata tra il 1107 e il 1117, posta tra il vecchio edificio che forse le sopravviveva durante la costruzione a nord e la nuova aula dei mosaici del camposanto dei canonici (4) a sud. quest’ultima sostituiva e/o in parte inglobava l’aula paleocristiana precedente di santo stefano. il terremoto del 1117 interrompeva questo nuovo progetto, facendo crollare quantomeno l’edificio all’interno del quale era conservato il corpo di sant’imerio (presumibilmente una delle due aule della basilica paleocristiana). solo dopo una decina d’anni, con un nuovo progetto che prevede la rasatura di tutti gli edifici preesistenti nell’area, si dà inizio all’attuale cattedrale romanica, consacrata nel 1196. hypothetical sketch of the different episcopal complex of cremona during middle age. in gray, the present, romanesque cathedral (after puerari, 1971). in bold the paleochristian complex: north side, the cathedral of saint mary (1, wall and mosaic remains); south, the minor church of saint steven, with apse remains (2); center, the octagonal baptistery, recently excavated in the crypt. the whole complex dates back to the 5th-6th cent. on the basis of archaeological data. dashed line indicates the complex presumably designed in the early 12th cent., as testified by the memorial stone (i.e., 1107 ad; see fig. 4); the saint mary church was placed between the old cathedral and saint steven, in the area of the paleochristian baptistery (3, mosaic remains) and (south) the new minor church of saint steven (? or saint himerius; 4, mosaics). this project was abruptly interrupted by the 1117 earthquakes, which caused, at least, the collapse of the church containing the body of saint himerius (presumably one of the two paleochristian churches), which was extracted from the ruins only 12 years later. the present romanesque cathedral (started few years later and consecrated in 1196) erased all the previous buildings. attestata da una monumentale lapide coeva (fig. 4) ispirata, nell’iconografia wiligelmica, a quella del 1099 nel duomo di modena. essa recita, in maniera apparentemente enigmatica, che nel 1107, fu intrapresa la costruzione di “hec maior aeccl[esi]a cremonenesis q[uae] media videt[ur]”. come a modena, anche qui, originariamente, la lapide avrebbe dovuto 22 imerio, santo calabrese, vescovo di amelia, fu traslato a cremona dal vescovo liutprando nel 971 (sicardus cremonensis, xii-xiii sec.) non si può escludere che esso, al momento del terremoto, fosse ancora nell’attigua vecchia cattedrale di santa maria che sopravviveva, almeno in parte, durante la costruzione della nuova. le macerie che ne occultarono le spoglie per lungo tempo poterono dunque essere anche quelle della vecchia chiesa; ma questo non cambia la valutazione sugli effetti e sulle conseguenze del terremoto a cremona. 23 la critica dell’arte più recente dilata di parecchio i tempi di costruzione delle cattedrali padane. tra anno di fondazione e consacrazione, non dell’altare del santo protettore – che poteva richiedere, tuttalpiù, la presenza della sola cripta – ma dell’edificio terminato si credono necessarie svariate decine di anni (paolo piva, univ. di milano, com. pers.). i terremoti del gennaio 1117 ... 92 stati rinvenuti materiali e mosaici pavimentali “in fase” con quelli noti dell’aula dell’attiguo camposanto dei canonici. entrambi i pavimenti appartengono a due fig. 4 lapide attestante la fondazione della cattedrale di cremona nel 1107, attualmente murata nella sacrestia vecchia. il q[uae] media videt[ur], riferito alla maior eccl[esi]a cremonensis, si riferisce all’originario progetto a più edifici, abbandonato in seguito al crollo del 1117. memorial stone of the foundation of the cremona cathedral in 1107, presently in the old sacristy. the sentence q[uae] media videt[ur] (“that you can see in the middle”), related to the maior eccl[esi]a cremonensis (“main church of cremona”, i.e., santa maria), can be understood if thinking to the original project with three buildings, abandoned after the collapse due to the 1117 earthquake (see fig. 3). fig. 5 lacerti di pavimentazione a mosaico dell’edificio posto ad oriente della chiesa principale (camposanto dei canonici, circa 3 m al di sotto dell’attuale pavimentazione del duomo), contemporanei a quelli rinvenuti ad analoga quota al di sotto della cripta attuale, ed attestanti con essi il progetto edilizio a doppia chiesa del 1107, abbandonato dopo il crollo nel 1117. remains of the mosaic floor found south to the present church (3 m below the present floor of the cathedral), contemporaneous to those excavated at the same elevation in the crypt of the cathedral. these mosaics, dated before 1117, belong to one of the churches of the original 1107 project, collapsed during the 1117 event. 24 l. passi pitcher, comunicazione personale. ma secondo p. piva, su base meramente stilistica, essi sarebbero della terza decade del secolo; comunicazione personale. 25 l’esistenza di due chiese e di un altro edificio nell’area del torrazzo scioglierebbe l’enigma dell’altrimenti inspiegabile media videtur della lapide di fondazione. a livello di ipotesi (vedi fig. 3), l’edificio nell’area del torrazzo potrebbe essere l’aula paleocristiana maggiore di santa maria, più o meno restaurata dopo il sacco di agilulfo; i mosaici della cripta potrebbero appartenere al progetto della nuova cattedrale “quae media videtur” (ante 1117), che inglobava il battistero paleocristiano, e quelli del camposanto dei canonici ad una nuova aula in sostituzione dell’aula minore paleocristiana intitolata a santo stefano (e/o a sant’imerio; quella in precedenza menzionata nel locale caldaie del duomo). col nuovo progetto della cattedrale romanica, non aveva neanche più senso apporre la grande lapide di fondazione in facciata, dal momento che essa descriveva una situazione a più edifici, non più attuale. distinti edifici a cui si è sovrapposta l’attuale cattedrale romanica e la loro quota è circa 3 metri sotto quella dell’attuale pavimentazione (3 e 4 in fig. 3). le stratigrafie archeologiche ed i connotati stilistici li collocano ad una data prossima, ma anteriore al 111724, testimoniando il perdurare dell’organizzazione architettonica del complesso cominciato nel 1107 a chiese doppie, tipica del periodo medievale presso i nuclei episcopali. non è ragionevole pensare che l’aula del prezioso ciclo a mosaici del camposanto (fig. 5) sia stata progettata o, men che mai, eseguita contemporaneamente alla cattedrale romanica, dal momento che quest’ultima si sovrappone p.p. alla prima. e’ cioè molto più verosimile credere che essa fu edificata (in toto o in parte) seguendo una prima fase progettuale (iniziata nel 1107) e subito abbandonata per un motivo di forza maggiore (i.e., il terremoto). dunque, queste chiese, tra cui la principale “quae media videtur” della lapide di fondazione25, sarebbero crollate con il terremoto del 1117, ed i loro ruderi dovettero caratterizp. galli zare a lungo il panorama locale se, come visto, il corpo di sant’imerio potè essere rinvenuto solamente nel 1129. purtroppo, le volte della cripta attuale cedettero, per motivi statici, nel xvii secolo ed i lavori che seguirono sconvolsero gran parte delle stratigrafie medievali, cancellando le tracce di eventuali livelli di crollo antichi e quant’altro26. come poc’anzi anticipato, bisogna aggiungere che diversi autori, ma per ultimo gandolfo (2001), sulla base di evidenze stilistiche ed architettoniche, hanno ipotizzato che una serie di frammenti marmorei decorati e di sculture, attualmente murati in facciata, nel cortiletto del torrazzo, nel cortile del castello sforzesco a milano o, infine, riutilizzati nel portale del transetto settentrionale, appartengano, tra l’altro, a due o più portali della cattedrale iniziata prima del terremoto, salvati in parte dal crollo, smontati, modificati, riscolpiti e rimessi in opera27 (fig. 6). un possibile indizio della riapertura del cantiere dopo il terremoto, ma con un nuovo e più ampio progetto, è la notizia secondo la quale papa callisto ii compone una lite tra il vescovo ed canonici della cattedrale che hanno ceduto la loro abitazione per un nobile fine, invero “ad ampliendam ecclesiam”28. questo documento è del 1124 e circostanzia ulteriormente il fatto che il corpo di sant’imerio fu rinvenuto solo dodici anni dopo il terremoto. con il nuovo cantiere, sotto la spinta di oberto da bovara (vescovo dal 1117 al 1162), si abbandona dunque il progetto dell’impianto a due aule e si procede alla costruzione di un'unica e monumentale cattedrale romanica, a tre navate con ampi transetti, la cui estensione ricopre, di fatto, l’area di tutte le precedenti costruzioni, compresa la nuovissima aula con i mosaici del camposanto dei canonici e la loro stessa residenza. il lungo lasso di tempo intercorso tra il crollo e la rimozione delle rovine potrebbe essere proprio giustificato, oltre che al fisiologico rallentamento di tutte le attività cittadine in seguito al terremoto, anche con il ripensamento progettuale di tutto il complesso episcopale. in ogni modo, nel 1138 la cattedrale è di nuovo a buon punto, come sembra potersi evincere da due documenti che dicono “…in platea quae est ante ecclesiam maiorem…” e “…juxta ecclesiam maiorem…” (codice diplomatico cremonese, viii-xiv sec.). di fatto, il 93 28 luglio del 1141, come recitava una lapide ora perduta (n. xli, in vairani, 188029), il vescovo oberto consacrò l’altare nella cappella di san giovanni, ed altri ne consacrò negli anni successivi (si veda in porter, 1916). finalmente, nel 1196, il corpo di sant’archelao, ma soprattutto quello del santo protettore imerio furono nuovamente traslati nella cattedrale, come ricorda una lapide tuttora visibile30 e come riportato nel chronicon cremonense e nei cronica di sicardus cremonensis (xii-xiii sec)31. nel complesso quindi, da quanto ci dicono le fonti e le evidenze di scavo, la struttura dell’attuale cattedrale romanica nulla avrebbe a che fare con quella intrapresa dieci anni prima del terremoto dal vescovo gualtiero32, a parte frammenti architettonici e scultorei reimpiegati nella ricostruzione e nelle aggiunte successive. 2.3 il terremoto in area emiliana il terremoto, come testimoniato dalla già accennata lapide, potrebbe essere la causa del crollo parziale (le coperture?) dell’abbazia di nonantola. se così fosse, quantomeno tra cremona e nonantola, gli effetti dello scuotimento sismico avrebbero dovuto interessare anche le città intermedie (fig. 1a). le fonti, in realtà, non dicono molto. parma è citata da cronache coeve di area europea come una delle città danneggiate (insieme a verona e venezia). questa circostanza è ripresa da cronache locali trecentesche, che aggiungono che “maxima pars ecclesia sancta maria dirupta fuit“ (chronicon parmense, xi-xiv sec.). secondo quintavalle (1974), tuttavia, la cattedrale di parma, cominciata verso l’anno 1090 e consacrata nel 1106, non mostrerebbe risarciture o ripensamenti dovuti al terremoto e sarebbe tutta pre-1117. dobbiamo quindi restare nel dubbio tra quanto asserito dalla fonte trecentesca e quanto ipotizzato dalla critica archeologica33. 26 a parte una lesione nelle murature del battistero paleocristiano mostratamai dalla d.ssa passi pitcher, ma poco significativa in termini archeosismologici. 27 anche i quattro bellissimi profeti (opera antecedente al terremoto, secondo cochetti pratesi, 1976. fig. 6b), che ancor oggi stanno in precaria e celata attesa, adattati come sono “di taglio” nella strombatura del portale duecentesco di facciata, secondo lo stesso gandolfo (2001) dovevano appartenere ad una primitiva decorazione ad ante del portale della chiesa del 1107 (come quella messa in opera vent’anni dopo a san zeno di verona; valenzano, 1993), dispiegando allora, “di fronte”, tutta la loro originaria espressività. a fianco, sulla sinistra, murati anch’essi in posizione invertita ed in successione verticale anziché orizzontale, vi sono altri coevi lacerti di un ciclo di storie della creazione, testimoniati da due bassorilievi rappresentanti la cacciata di adamo ed eva ed il peccato originale (fig. 6c). 28 l’edificio dovette essere, cioè, abbattuto per fare spazio alla nuova, maestosa cattedrale romanica. 29 ma sembrerebbe essere quella commemorativa di una cappella di santo stefano, ora murata presso l’archivio diocesano, sempre del 1141, quinto kalendas augusti, cioè 28 luglio. 30 l’ho rinvenuta nella cripta, nonostante porter (1916) e tutti a seguire la diano per persa. 31 secondo una lapide dispersa tramandata da bresciani (xvii sec.) la cattedrale fu consacrata dal vescovo sicardo nel 1190, alla presenza di re, vescovi e regine. questa notizia, considerata vera da tutti gli storici successivi, finanche da porter (1916), è assolutamente falsa e piena di errori grossolani (si veda in gallina, 1986). basti pensare che sicardo, nei suoi cronica, non menziona minimamente questo avvenimento di straordinaria importanza. 32 la cui morte, avvenuta nei primi giorni del 1117 (grandi, 1856), si potrebbe suggestivamente ascrivere, in modo diretto o meno, al crollo della cattedrale da lui voluta. in realtà non esistono fonti primarie a questo proposito e la sede vescovile potrebbe essere stata allora addirittura vacante. 33 abbiamo detto come altri reputino questo lasso di tempo insufficiente alla costruzione di edifici così imponenti, dove la data di consacrazione potrebbe riferirsi al solo sacello del protettore. in questo caso, come a cremona, la chiesa potrebbe essere tutta post-terremoto e la mancanza di cesure nelle cortine murarie non testimonierebbe la mancanza di effetti rilevanti a parma. i terremoti del gennaio 1117 ... per piacenza non esistono fonti contemporanee. l’unico indizio è la data di ricostruzione della cattedrale romanica, contenuta in una lapide in facciata: 1122, cinque soli anni, cioè, dal terremoto34. la primitiva basilica, fondata nel 887 (vedi in stocchi, 1984), potrebbe essere stata danneggiata e quindi abbattuta per far posto alla nuova. ma anche in questo caso, seppur non trascurando la coincidenza delle date, si resta nel campo delle ipotesi. analogamente a quanto asserito per piacenza, per castell’arquato (pc) una fonte tarda (campi, 1651), ma generalmente attendibile, dà la riconsacrazione 94 fig. 6 parte degli arredi scultorei e degli elementi architettonici messi in opera o preparati durante il primo cantiere della cattedrale (1107-1117), recuperati, ma non riutilizzati o destinati ad una funzione/collocazione diversa dall’originaria, successivamente al crollo causato dal terremoto del 1117: a, fregio fogliato nell’intradosso dell’architrave del portale del transetto nord (originariamente facciavista dell’architrave di un portale in facciata); b, i quattro profeti (geremia, isaia, daniele, ezechiele) riattati di taglio nella strombatura del portale duecentesco, ma opera di un maestro attivo prima del 1117 (cochetti pratesi, 1976); c, storie della creazione e frammento di stipite di portale nel sottoportico alla sinistra del portale centrale; d, frammenti di stipiti di portali, attualmente conservati al museo del castello sforzesco a milano; tutti questi frammenti, scolpiti prima del 1117, appartenevano ai tre portali in facciata della cattedrale prima del crollo (gandolfo, 2001). i due pannelli superstiti delle storie della creazione, originariamente montati in successione verticale a lato del portale centrale, furono riattati in posizione invertita ed in orizzontale. i profeti erano stati concepiti, così come i pannelli della creazione, per essere posti di faccia ai lati del portale della cattedrale interrotta nel 1117(gandolfo, 2001). remains of some sculptures and architectonic elements belonging to the church started in 1107, which have been recovered and reutilized after the 1117 collapse (see gandolfo, 2001, for details). 34 “centum viceni duo christi mille fuere anni cum ceptum fuit hoc laudabile tempium” p. galli della chiesa carolingia dell’assunta al 1122. a fidenza35 (pc), la cattedrale ricostruita sulle spoglie di quella cadente del ix-x secolo (tassi, 1990), e probabilmente consacrata nel 1106, fu ristrutturata ampiamente da benedetto antelami alle soglie del xiii secolo, venendo riconsacrata nel 120736. anche in questo caso, in assenza totale di fonti, resta il dubbio di una chiesa consacrata nel 1106 e poi ripensata completamente pochi decenni dopo. a modena non abbiamo fonti che attestino danni alla città od alla nuovissima (od in fieri?) cattedrale. la cronologia del massimo tempio mutinense è scandita inequivocabilmente da documenti coevi (relatio traslationis; vedi in stocchi,1984) e da tre lapidi ancora presenti nelle mura. essa fu fondata nel 1099 (su una precedente basilica già in rovina), nel 1106 ne fu consacrato l’altare e solamente nel 1184 la cattedrale fu finalmente consacrata. le opinioni degli storici dell’arte sono però divergenti sulle fasi costruttive. secondo alcuni nel 1106 il progetto dell’architetto lanfranco era ultimato (quintavalle, 1982), secondo altri (in stocchi, 1984) la costruzione della chiesa procedette per decenni, inglobando progressivamente la presisitente, ed il 1106 segna solo la consacrazione di un altare posto in cripta. resta il fatto che gli 85 anni per costruire un edificio molto più piccolo di quello di cremona paiono veramente molti senza pensare ad un qualcosa che ne interruppe, ad un certo punto, i lavori, come ipotizzato da montorsi (1984). bologna, infine, molto distante dalle località danneggiate, non ha fonti contemporanee che ne descrivano gli effetti, sebbene il terremoto sia citato, con danni, dalle cronache del xv-xvii secolo37. nel complesso nulla di certo emerge dall’insieme delle poche, generalmente non coeve e/o locali fonti; né ipotesi tra loro concordanti e/o definitive possono essere tratte dall’analisi architettonica degli edifici attuali. seppur un forte risentimento sia innegabile, in mancanza di dati desumibili da moderni scavi archeologici, gli effetti reali del 1117 in area emiliana restano di incerta entità ed estensione. 3. quadro sismotettonico del cremonese diversamente dai settori di catena appenninica, ove i ratei di deformazione e la competenza delle formazioni affioranti sono sufficientemente elevati da permettere spesso l’affioramento e la conservazione dell’espressione superficiale delle strutture sismogenetiche profonde (p.e., “nastri” e scarpate connessi a faglie prevalentemente dirette), nella pianura padana i possibili indizi di tettonica attiva sono labili e generalmente relativi a blande deformazioni continue, espressione indiretta di movimenti profondi su faglie a cinematica generalmente inversa ed a basso angolo. tali faglie sono relative al complesso sistema frontale di accavallamento degli edifici appenninico ed alpino, di età principalmente messiniana e pliocenica, le cui principali fasi traslative sono scandite, sino al pliocene medio-superiore, dalla presenza di grandi cunei sedimentari a geometria sintettonica (vai et al., 1989). anche i livelli di sismicità dei due dominii, appennico e padano, non sono paragonabili, essendo caratterizzato il primo da eventi di magnitudo elevata (m≥6.5 in appennino centrale e m≥7.0 in quello meridionale), il secondo da eventi generalmente con m≤5.5. solo negli ultimi anni, grazie a dati strumentali relativi alla profondità e al meccanismo focale degli eventi registrati dalla rete sismica nazionale (ingv) e da quelle locali, nonchè a considerazioni di carattere morfotettonico, è stato possibile formulare delle ipotesi sulle caratteristiche sismogenetiche di alcuni tratti dell’area della bassa padana (p.e., terremoto di correggio del 1996, mw=5.4: galli, 1996; terremoto della valle dell’oglio del 1802, ma=5.5: burrato et al., 2003). 3.1 indizi geologici di attività tettonica recente. come detto, nella pianura padana, celati dalle coltri dei depositi plio-pleistocenici, si fronteggiano, con vergenza rispettivamente settentrionale e meridionale, i sistemi di thrust appenninici ed alpini (fig. 1b). al di sotto di questi sistemi, a circa 10 km di profondità, è presente un basamento magnetico anch’esso coinvolto p.p. in sovrascorrimenti non necessariamente in relazione geometrica con quelli del multilayer sedimentario mezo-cenozoico (cassano et al., 1986), ed immergente al di sotto del fronte pedeappenninco, ove raggiunge i 14-15 km. tale basamento presenta delle importanti zone di svincolo trasversale, orientate circa ns e nnessw, che dalla zona dei fronti si estendono per decine di chilometri nell’avampaese (vai, 1989; cnr, 1991; agip, 1996). la distanza dei fronti più esterni appennico ed alpino raggiunge proprio a nordovest di cremona un valore minimo, fino all’accavallamento dei primi sui secondi (area di soresina; figg. 7-8; fantoni et al., 2004). nello specifico, l’area della bassa padana occidentale è caratterizzata in profondità dalla presenza dell’arco di pavia ad ovest e delle pieghe ferraresi ad est. il primo, da voghera, con ampio raggio si protende verso nord, attraversando il po, per poi inflettersi verso sudest, passando sotto cremona, parma e reggio emilia, oltre la quale incontra la terminazione occidentale delle pieghe dell’arco ferrarese (fig. 1b) e dove massimo risulta anche lo spessore dei depositi plioquaternari all’esterno del suo fronte (oltre 7000 metri; p.e., cnr-pfg, 1983). la recente mobilità dell’arco di pavia si palesa direttamente in superficie in diversi punti della piana. il sollevamento di tutta l’area di stradella (a se di pavia), anche a nord del po, ha comportato infatti l’affioramento delle calcareniti messiniane nell’alveo del po stesso. 95 35 all’epoca borgo san donnino. 36 sia all’interno che all’esterno si riconoscono materiali di reimpiego della fase di xi-xii secolo, talvolta così preponderanti “da sembrare quasi restauri di vecchie strutture” (tassi, 1990; p. 123). 37 così, nella cronaca quattrocentesca di francesco pizolpassi, nell’anno 1147 è ricordato un terremoto per il quale caddero edifici in città. questo evento, sconosciuto a tutte le altre fonti note potrebbe essere un errore dell’autore, testimoniando invece gli effetti a bologna del terremoto del 1117: “… el teremote per el qual ruvinone multi edificii e in fra le altre la tora felicianorum in la via de piaza maiore, la qual, cadendo, guastò [-] le loro case e vene' ad habitare in la vale de l'ausa…". a meno che non si tratti del terremoto del 1174, ricordato nelle histor. miscell. bonomiensis (vedi, muratori, rerum ital. script., xviii, 242.) i terremoti del gennaio 1117 ... tale sollevamento, a giudicare dal possibile basculamento verso est di diverse superfici alluvionali coperte da loess nei dintorni di stradella, potrebbe essere perdurato anche nel corso del pleistocene superiore, così come testimoniato da altri indizi geomorfologici (in tellini e pellegrini, 2001). l’anticlinale di san colombano (tra cremona e pavia. 70-80 m sulla pianura circostante; desio, 1965. fig. 1b, 7) è bordata a sudest da una probabile scarpata di faglia. secondo tellini e pellegrini (2001) alcune evidenze superficiali (come la deviazione del lambro e basculamenti e sollevamenti di superfici di età tardopleistocenica) testimoniano un perdurare dell’attività tettonica anche in tempi recenti della struttura afferente all’alto strutturale. poco più ad est, a sw e nw di casalpusterlengo (fig. 7), desio (1965) ha evidenziato un altro alto sotteso da un’anticlinale wnw-ese fagliata che coinvolge nella deformazione anche la successione quaternaria. più ad est, sul fronte più esterno all’arco di pavia, un fenomeno di antecedenza dell’oglio nei pressi di bordolano (circa 15 km a nord di cremona; marchetti et al., 1980. fig. 7) potrebbe testimoniare la continua crescita dell’omonima anticlinale (pieri e groppi, 1981) in epoca post-glaciale. sempre in ambito cremonese, ma relativamente ai domini alpini sepolti a vergenza appenninica, si segnala il pianalto di romanengo (di età pleistocenica mediosuperiore; desio, 1965; cremaschi, 1987. fig. 1b, 7), sulla cui interpretazione in chiave neotettonica si era già espresso desio (1965). si potrebbe infatti trattare di un alto controllato dalla sottostante anticlinale fagliata e-w (desio, 1965, su dati agip, segnala il coinvolgimento del quaternario sepolto nella deformazione; vedi anche fantoni et al., 2004) e modellato solo marginalmente dai corsi d’acqua nel post glaciale. il ripiano termina a nord e a sud con una graduale immersione verso la pianura. più a sud, oltre soresina, è presente un evidente dosso fluviale messo in relazione con il grande paleoalveo n-s dell’oglio; la rilevanza di detto dosso è stata ipoteticamente collegata (pellegrini, 2003) al sollevamento recente dell’anticlinale e-w di caviaga (pieri e groppi, 1981). ulteriori indizi di tettonica attiva desumibili da possibili variazioni negli andamenti planimetrici dei corsi d’acqua sono segnalati ad est di cremona, in una zona tra il po e l’oglio che tenderebbe a sollevarsi (presumibilmente lungo l’asse wnwese dell’anticlinale fagliata – a ne di piadena; pieri e groppi, 1981), allontanando, di fatto a nord ed a sud il corso degli anzidetti fiumi (pellegrini, 2003). il po, infatti, tra cremona e casalmaggiore, è molto discostato dal livello fondamentale della pianura, ampliando la sua valle attuale da 600 m in prossimità del capoluogo a oltre 10 km a casalmaggiore (fig. 7; gerevini, 1998). l’assenza di tracce di centuriazione romana in questa zona (tuttora fortemente caratterizzanti tutto l’agro cremonese; tozzi, 2003) fornisce, inoltre, un indizio cronologico riguardo la migrazione del po verso sud. sollevamento e migrazione degli alvei (con conseguente cancellazione delle tracce di centuriazione) sarebbero infatti avvenuti in epoca medievale/ moderna. per quanto concerne invece la possibile attività recente delle strutture dell’arco di ferrara, oltre che da dati di borehole breakouts (montone e mariucci, 1999), essa potrebbe essere testimoniata dalla continua depressione della sinclinale posta a tergo dell’anticlinale frontale dell’arco. tale struttura avrebbe condizionato in superficie il drenaggio verso il po del secchia e del panaro in epoca post ultimo massimo glaciale (castaldini et al., 1979). 3.2 sismicità. come accennato, il livello di sismicità della bassa padana occidentale è modesto se comparato ad altre aree della penisola italiana, non superando storicamente magnitudo 5.5 ed un’intensità epicentrale di viii 96 fig. 7 schema delle principali strutture plicative sepolte nell’area nordorientale dell’arco di pavia (da agip, 1959; desio, 1965; pellegrini, 2003; vedi fig. 1° per localizzazione). la campitura con “lack of centuriation” indica l’area della bassa cremonese ove il tracciato delle centuriazioni romane è stato forse cancellato dalla deriva verso sud del corso del po (pellegrini, 2003). questo fenomeno, accaduto in epoca medievale, potrebbe essere dovuto alla deformazione superficiale (cosismica?) dell’anticlinale di piadena. in questo senso la struttura di piàdena potrebbe essere una delle possibili sorgenti dell’evento basso padano del 1117. sketch of the main folds and faults buried in the northeastern area of the pavia arch (modified from agip, 1959; desio, 1965; pellegrini, 2003; see fig. 1a for location). hatch with “lack of centuriation” indicates the area where the roman centuriation, still visible elsewhere, has been erased by the southern drift of the po river. this phenomenon, occurred during middle age, could be attributed to the coseismic uplift of the piadena anticline. if this were true, the piadena buried thrust could be considered one of the seismogenetic source of the 1117 multiple event. p. galli grado mcs (gruppo di lavoro cpti, 1999). i terremoti, a parte quello di soncino del 1802 (ma=5.5, io=viii mcs), sono generalmente ubicati tra reggio emilia e parma, ed a nw di quest’ultima (fig. 1b). per quanto riguarda cremona, escludendo il terremoto del 1117, gli effetti risentiti dalla città sono sempre stati inferiori al vii grado (raggiunto, forse, in occasione del terremoto bresciano del 1222; boschi et al., 1995), essendo valutabili risentimenti di vi grado in occasione di altri cinque terremoti storici (tre di ambito locale e di m<5; 1276, 1829 e 1951; due risentimenti di eventi distanti; 1832 e 1914). secondo cavitelli (1588; ma non in gruppo di lavoro, 1999) altri eventi furono fortemente risentiti in cremona nel 1280 (posto a bologna in baratta, 1901), nel 1287 (in baratta, 1901) e nel 1397 (posto nel bergamasco in baratta, 1901), in occasione del quale “multa edificia corruerunt”. il quadro indiziario fornito dagli elementi di carattere geomorfologico, strutturale profondo e sismologico, nel complesso, permette di ipotizzare una possibile attività tettonica residua legata al complesso sistema di accavallamento delle unità appenniniche ed alpine sepolte e del sottostante basamento flessurato. per la struttura di romanengo è, ad esempio, evidente la concordanza ed il probabile nesso causale tra la distribuzione del danneggiamento in occasione del terremoto del 1802, così come rivalutata da albini et al. (2002; sorgente circa e-w), e la geometria dell’anticlinale fagliata sottostante (vedi desio, 1965). analogamente, per il terremoto del 1996, sulla base dei dati strumentali e di sismica di esplorazione (agip, 1996, in galli, 1996) sono state avanzate ipotesi concernenti l’attivazione della rampa laterale della struttura sepolta del cavone e/o di una zona di taglio n-s nel sottostante basamento magnetico. quindi, limitatamente all’arco pavese ed al prospiciente arco alpino, mentre è presumibile che singole e limitate strutture sepolte (p.e. thrust od elementi di svincolo trasversale di lunghezza ≤10 km) siano responsabili specificatamente dei terremoti storici di moderata energia (p.e. quelli del 1438, 1802 e 1832) e strumentali (1971 e 1996), non è assolutamente chiaro quale possa essere il potenziale sismogenetico (inteso come massimo terremoto attendibile) di un’eventuale attivazione congiunta di più strutture sepolte (o di una di dimensioni >10 km) o di grandi porzioni degli elementi di svincolo presenti nel sottostante basamento. 4. discussione e conclusioni per tutto quanto accennato riguardo il terremoto del 1117, appare chiaro che l’attuale ubicazione epicentrale dello stesso (presso verona, gruppo di lavoro cpti, 1999) non rispecchia la complessità dell’evento, invero la distribuzione del danneggiamento desumibile dalle fonti coeve. tralasciando gli effetti di area germanica e pisana appare, infatti, molto difficile attribuire i crolli di località distanti oltre 80 km ad una struttura sismogenetica pedealpina, la stessa che certamente fu la causa del danneggiamento nell’area veneto-trentina. tuttavia, proprio a questo riguardo, non si deve ignorare che un forte risentimento verso sud, anche con danni localizzati (p.e., a guastalla, vii mcs: boschi et al., 1995), abbia avuto luogo in occasione del terremoto dell’asolano del 1695 (io=ix-x, ma=6.6. fig. 1b, associato al thrust asolo-cornuda da galadini et al., 2002. risentito, però, come v mcs a cremona) e, più dubitativamente nel 1222 (terremoto del bresciano; io=viii-ix, ma=6.0; con effetti a modena di vii mcs, secondo boschi et al., 1995). analoghi effetti di “ripresa” delle intensità ai margini pedemontani alpino ed appenninico sono stati evidenziati da magri e molin (1986) per terremoti minori del xix e xx secolo. ritornando al 1117, sulla possibilità di un evento multiplo con aree sorgente separate, galadini e galli (2001) hanno ipotizzato l’attivazione penecontempoeanea di un settore del fronte alpino sud-vergente a se dei m.ti lessini e di parte del fascio delle giudicarie (i.e., il thrust di monte baldo). in realtà, analisi paleosismologiche condotte ad hoc su faglie oloceniche nel dominio lessinio e giudicariense dagli stessi autori non hanno supportato questa ipotesi (galadini et al., 2001a). la mancanza di altri indizi di tettonica attiva lungo le strutture pedemenontane prospicienti verona ed il livello di danneggiamento sofferto dalla stessa in occasione di forti terremoti di origine veneto-friulana hanno quindi indotto galadini et al. (2001b) a ipotizzare per il 1117 una sorgente più orientale, presumibilmente identificabile col thrust thiene97 fig. 8 profilo geologico semplificato lungo una sezione ~nne-ssw nella pianura padana centrale. e’ evidente la deformazione dei depositi quaternari in corrispondenza delle anticlinali di crescita. (da un profilo sismico convertito in profondità in fantoni et al., 2004). depth-converted, ~nne-ssw geological section from a seismic profile in fantoni et al. (2004). the section shows the deformation (warping and faulting ?) of the quaternary sequence in the central po plain. i terremoti del gennaio 1117 ... bassano (fig. 1b. galadini et al., 2002). un epicentro connesso a tale struttura, adiacente quindi a quello del 1695 ed ancora più distante dagli effetti registrati nella bassa padana, evoca, a maggior ragione, l’occorrenza di uno o più eventi separati, seppur avvenuti negli stessi giorni/ore, in prossimità dell’area di danneggiamento lombardo-emiliana. tuttavia, lo stato attuale delle conoscenze, storiche da un lato e geologiche dall’altro, non permette di definire quali o quante strutture sepolte, tra quelle potenzialmente suscettibili di generare terremoti, possano essersi attivate. da un lato, dando credito alla lettura in chiave cosismica degli effetti descritti dalla lapide di nonantola, agli indizi di danno in area emiliana, alle notizie sincrone non locali (o locali, ma tarde) di crolli a parma, sino a cremona, saremmo di fronte ad un’area di danneggiamento estesa lungo 100 km di fronte appenninico sepolto (tralasciando le notizie di ambito non locale e non coeve di milano e bologna). tale area richiederebbe l’attivazione penecontemporanea di diverse strutture sepolte tra l’arco ferrarese e quello pavese. limitandosi invece ai soli dati abbastanza attendibili di cremona (storici ed archeosismologici), unitamente al quadro di risentimento certo delineato dalle fonti coeve (milano) e dagli atti notarili dell’area tra piacenza e brescia, ci si potrebbe prefigurare con un’ipotesi di minima l’attivazione di una struttura sufficientemente grande e vicina a cremona da causare il crollo del complesso episcopale e, eventualmente, da provocare danni nelle città limitrofe (p.e., parma), possibilmente cumulando gli effetti con il forte risentimento dovuto al mainshock di pertinenza pedealpina, così come nel caso esemplificato dal citato terremoto asolano del 1695. tale struttura andrebbe ricercata tra quelle per le quali la letteratura ha indicato indizi di attività tardo pleistocenica (p.e., colombano, casalpusterlengo, bordolano, piàdena), tutte all’incirca di dimensioni di 10-20 km e potenzialmente capaci, perciò, di generare eventi di m≅ 6.2-6.5, invero caratterizzati da capacità distruttiva locale (p.e., ix mcs) e di un forte risentimento areale, non scevro da danni isolati (vii mcs). tra queste, quella di piàdena, come detto, sembrerebbe essere stata attiva in tempi storici, ed eventualmente post-romani, con una deformazione areale in superficie sufficiente a spingere il corso del po a sud e dell’oglio a nord. tale fenomeno, se non imputabile ad un sollevamento temporalmente continuo negli ultimi 2000 anni (ma quindi asismico), ma bensì discreto (e quindi cosismico), potrebbe essere ipoteticamente connesso all’occorrenza di un epicentro locale della sequenza del 1117. ringraziamenti la d.ssa l. passi pitcher (soprintendeza archeologica della lombardia), nel dicembre 2003, mi ha pazientemente illustrato tutte le evidenze di scavo relative alla cattedrale di cremona. gran parte delle ipotesi relative al crollo ed alla ricostruzione del duomo di cremona sono state formulate insieme e grazie a lei. ringrazio il prof. p. piva (università di milano, dipartimento di storia delle arti, della musica e dello spettacolo) per le proficue discussioni sulle vicissitudini edilizie delle cattedrali padane nel medioevo. ringrazio la d.ssa m. volontè (museo civico di cremona), la d.ssa v. leoni (università di pavia) e il dr. r.camassi (ingv) per l’aiuto fornito. andrea tertulliani e diego molin hanno rivisto e corretto il manoscritto, fornendo utili e sostanziali suggerimenti. bibliografia citata agip (1959) relazione geologica e mineraria sulla pianura padana, in: i giacimenti gassiferi dell’europa occidentale, accademia nazionale dei lincei, ii, roma. agip (1996) attività sismica registrata dalla rete agip nell’area di correggio, 1993-1996. rapporto interno. alberto di bezano (xiv sec.) alberti de bezanis abbatis s. laurentii cremonensis cronica pontificum et imperatorum, mgh, scriptores rerum germanicarum in usum scholarum separatim editi, iii, ed. holder-hegger, 1908. albini p., burrato p., valensise g. 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(1987) palesols and vetusols in the central po plain (northern italy), unicopli, studi e ricerche sul territorio, milano. cronichella cremonese (xi-xiii sec.) in a. dragoni, 1818 in eunte, miscellanee cremonesi, biblioteca statale di cremona, dep. lib. civica, ms aa6.1, p.182. desio, a., 1965. i rilievi isolati della pianura lombarda ed i movimenti tettonici del quaternario. ist. lombardo accademia di scienze e lettere, rendiconti, classe di scienze (a), 99, 881-894. donazione di decima (xii sec.) archivio di stato di verona, fondo clero intrinseco, b. 13, cart. n. 7, copia del 1327. enel (1986) il terremoto del 3 gennaio 1117, studi ed indagini per l’accertamento della idoneità tecnica delle aree suscettibili di insediamento di impianti nucleari, regione lombardia, area viadana, indagini di sismicità storica, rapp. finale, ismes-ratdgf-0012, 907 pp. fantoni r., bersezio r., forcella f. 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(1963) epigraphica pisana: testi latini sulla spedizione contro le baleari del 1113-1115 e su altre imprese antisaracene, in "miscellanea di studi ispanici," vi. scardeone b. (1560) de antiquitate urbis patavii, basileae. s icardus c remonensis (xii-xiii sec.) cronica, monumenta germanica historica, scriptores, 31, ed. holder-egger, 1903, pp. 22-183. stocchi s. (1984) l’emilia-romagna, in: chierici s. (a cura di), italia romanica, jaka book, milano. tassi r. (1990) il duomo di fidenza, silvana editoriale, cinisello balsamo. tellini c., pellegrini l. (2001) – forme di origine tettonica, note illustrative della carta geomorfologia della pianura padana, suppl. geogr. fis. dinam. quat., iv, 55-199. tozzi p. (2003) gli antichi caratteri topografici di cremona, in: p. t o z z i (a cura di), storia di cremona. l’età antica, banca cremonese credito cooperativo, 96-129. vai g.b. (1989) migrazione complessa del sistema fronte deformativo-avanfossa-cercine periferico: il caso dell’appennino settentrionale. mem. soc. geol. it., 38, 95-105. vairani t.a. (1880) inscriptiones cremonenses universae, cremona. valenzano g. (1993) la basilica di san zeno in verona. problemi architettonici, vicenza, 93-102. 100 ms. ricevuto il 18 gennaio 2005 testo definitivo ricevuto il 10 marzo 2005 ms. received: january 18, 2005 final text received: march 10, 2005 p. galli imp. sardella iittaalliiaann pplliioo--pplleeiissttoocceennee mmaammmmaall bbiioocchhrroonnoollooggyy aanndd ccoorrrreellaattiioonn wwiitthh mmaarriinnee sseeqquueenncceess:: tthhrreeee ccaassee ssttuuddiieess rraaffffaaeellee ssaarrddeellllaa11,, cchhiiaarraa aannggeelloonnee22,, ggiiaannccaarrlloo bbaarriissoonnee22,, ccllaauuddiiaa bbeeddeettttii11,, eemmaannuueellee ddii ccaannzziioo11,, ffeeddeerriiccaa mmaarrccoolliinnii22 && eennrriiccoo ssqquuaazzzziinnii33 1dipartimento di scienze della terra, università degli studi “la sapienza”, piazzale a. moro, 5 – 00185 rome, italy; 2dipartimento di scienze geologiche, università degli studi roma tre – largo s. leonardo murialdo 1 – 00146 rome, italy; 3museo paleontologico “ex chiesa di s. tommaso”, vico catina, 24 – 05100 terni, italy. e-mail address: raffaele.sardella@uniroma1.it summary the use of the biochronological units, based on the occurrence and evolutionary degree of the mammals, in the correlation between marine and continental sequences, in some cases enables a more detailed definition of the age of the sequences, but in other cases shows a more complex framework. in this paper three case studies will be pointed out: mandriola (sardinia, early pliocene-middle pliocene boundary), lower valdarno (tuscany – plio-pleistocene boundary) and tiberino river basin (umbria pliocene pleistocene boundary). biochronological criteria can be considered a very useful tool to infer age determination in the case of mandriola fossiliferous site. the interpretation of the marine and non marine fossil record of lower valdarno and tiber river basin lead to two different scenarios: 1) the italian peninsula can be considered as a refugium area for the pliocene taxa, which survived until the earliest pleistocene; 2) the age of deposits previously referred to early pleistocene has to be considered older (late pliocene). riassunto le unità biocronologiche, basate sulla comparsa e sul grado evolutivo delle diverse associazioni a mammiferi, rappresentano un importante strumento per la correlazione tra le sequenze marine e quelle continentali. in alcuni casi questa metodologia di lavoro porta a una maggiore definizione dell’età del deposito e della sequenza stratigrafica; in altri, invece, le unità biocronologiche mettono in evidenza un quadro più complesso. in questo lavoro vengono presi in considerazione tre casi di studio: mandriola (sardegna passaggio pliocene inferiore-medio), il valdarno inferiore (toscana – passaggio plio-pleistocene) e il bacino tiberino (umbria – passaggio pliopleistocene). i criteri biocronologici si sono rivelati uno strumento assai utile per definire con maggior dettaglio l’età di un deposito fossilifero nel caso del sito di mandriola. l’interpretazione dei ritrovamenti paleontologici provenienti dalle successioni marine e continentali del valdarno inferiore e del bacino tiberino conducono alla definizione di due scenari: 1) la penisola italiana come area rifugio per taxa pliocenici, qui sopravvissuti sino alle prime fasi del pleistocene; 2) l’età di depositi in precedenza attribuiti al pleistocene inferiore deve essere considerata più antica (pliocene superiore). keywords: biochronology, marine/continental correlation, fossil vertebrates, plio-pleistocene parole chiave: : biocronologia, correlazioni marino-continentale, vertebrati fossili, plio-pleistocene il quaternario italian journal of quaternary sciences 1166(1), 2003, 15-20 iinnttrroodduuccttiioonn in 1997 gliozzi et al. published an integrated biochronological framework based mainly on mammal faunal assemblages and their evolutionary degree. such a biochronological framework for pliocene and pleistocene can be considered a first step for correlating continental and marine sequences. the comparison between biochronological and biostratigraphical data enables in some cases a more detailed correlation of the sequences, while in other cases such a correlation does not seem to fit perfectly. in this paper three case studies will be presented, illustrating those two situations. 11)) iinnffeerrrriinngg aaggee ccoonnssttrraaiinnttss ttoo mmaarriinnee ssuucccceessssiioonnss bbyy mmeeaannss ooff ccoonnttiinneennttaall ffoossssiill vveerrtteebbrraatteess:: tthhee mmaannddrriioollaa ffoossssiilliiffeerroouuss ssiittee ccaassee ssttuuddyy age determination of the various formations outcropping in the sinis peninsula (western sardinia, italy) and their stratigraphical correlations have been for a long time a matter of debate. actually, each formation outcrops in a very limited area, most of the time they show no visible stratigraphical continuity or heteropy with other formations, and usually lacks significant fossils. nonetheless, a revision of the lagomorph and rodent content of the mandriola fossiliferous site (southern coast of the capo mannu peninsula, northern portion of the sinis peninsula; fig. 1) fixed a constraint to the age of the enclosing formations. the fossiliferous layer consists in a lens (3 m thick in its central part and approximately 10 m long) of silt and sands accumulated in a coastal lagoon (esu, 1986). the lens lies at the base of the capo mannu fm., consisting of various sand complexes of aeolian origin (pecorini et al., 1974; carboni & lecca, 1995). the capo mannu fm. overlies the shallow water marine limestones of the calcari di mandriola fm. (fig. 1), whose depositional facies becomes shallower from bot16 r. sardella et al. tom to top. all the complex represents a transition from a marine littoral environment to a continental aeolian one (carboni & lecca, 1995). the non-marine molluscs found in the deposit unfortunately cover too wide a stratigraphical range (pliocene; esu, 1986) to be useful for age determination. fossil vertebrates of the lagoonal sediments were at first illustrated in a preliminary note by pecorini et al. (1974), who inferred an early pliocene age (ruscinian, mn14; for a synoptic mn zones mammal ages chronostratigraphic chart, see esu, 1999) for the deposit due to the presence of the murid rhagapodemus hautimagnensis. this opinion was in later years reconsidered by other palaeontological studies (lópez martínez & thaler, 1975; esu & kotsakis, 1985). on the other hand, regional stratigraphy data assigned the mandriola fossiliferous site to middle pliocene (carboni & lecca, 1995). the new systematic attribution of one faunal element (the murid rhagapodemus azzarolii; angelone & kotsakis, 2001) has been one of the factors that led to the reconsideration of the age of the deposit. r. azzarolii underwent only slight morphological and morphometric modifications if compared with its continental ancestor (r. ballesioi mein & michaux, 1970): that may demonstrate that its colonisation of sardinia occurred a short time before the deposition of the lagoonal sediments (for a synthesis on insular environment induced modifications on vertebrates see azzaroli, 1982). the temporal distribution of r. ballesioi in central and western europe covers part of mn14 to early mn15 (middle-upper zanclean), fixing a lower age boundary for its arrival on the island. an upper limit could be established by the presence of prolagus aff. p. depereti, derived from p. depereti lópez, 1975, only known in late ruscinian assemblages (mn15, late early pliocene – earliest middle pliocene). for these reasons, the arrival of these faunal elements in sardinia and the age of the mandriola fossiliferous site is considered to be the zanclean-piacenzian boundary (angelone & kotsakis, 2001). the difficulty in using a common biochronological tool (such as evolutionary degree of faunal elements) to compare continental faunas and insular ones, in this case has fortunately been avoided. 22)) nneeww ppeerrssppeeccttiivveess iinn lloowweerr vvaallddaarrnnoo ssttrraattiiggrraapphhyy bbyy mmeeaannss ooff mmaammmmaall ffaauunnaass in lower valdarno area (tuscany, italy) sediments spanning from early pliocene to late pleistocene – holocene outcrop. the marine pliocene cycle deposits are represented by the “sabbie gialle” fm outcropping either on the left and on the right-hand side of the arno (fig. 2). the end of this cycle is commonly considered to be middle pliocene in age, as attested by the micropaleontological content of the deposits on the left-hand side of the arno river (bossio et al., 1981). in this area the transgressive overlying sediments of the “sabbie e argille ad arctica islandica” fm are discordant over the sabbie gialle fm. and represent the early pleistocene marine ingression. another interpretation is suggested by the recent study of casa sgherri (santa croce sull’arno, pisa) mammal fauna and of the findings at vinci, in the surroundings of fucecchio (firenze), on the right-hand side of the arno, in continental sediments correlated to the post-pliocene marine cycle of the left-hand side (fig. 2). germanomys sp. (arvicolidae, rodentia) has been found in the “conglomerati di vinci”. it is related to middle to early late pliocene (mn15b-16b) (fejfar, 2001). together with germanomys, remains of e. ex gr. e. stenonis-senezensis have been recovered. such a finding, even if without a specific attribution, reduces the time span to late pliocene (costa san giacomo-olivola f.u.), since either e. stenonis cocchi and e. senezensis prat are widespread in western europe in sites correlated with late pliocene and earliest pleistocene (alberdi et al., 1998). a few km westward in the sediments of the massarella unit, related to those of vinci, the casa sgherri local fauna has been found (marcolini et al., 2000; marcolini, 2001, marcolini, in press). large and small mammals have been recovered and the assemblage seems to be related to the late pliocene. as to large mammals, the contemporary presence of enhydrictis ardea (bravard), acinonyx pardinensis (croizet & jobert), sus strozzii meneghini and macaca sylvana florentina (cocchi) has important biochronological meanings since such an assemblage indicates a time lapse comprised between the costa s. giacomo f.u. and the olivola f.u. as to small mammals, mimomys ostramosensis janossy & meulen and fig. 1 location of the mandriola fossiliferous site and lithological section of the outcrop. 1. calcari di mandriola fm. limestones, deeper water facies; 2. calcari di mandriola fm. limestones, shallower water facies; 3. first dunar complex of the capo mannu fm.; p.s.l.: present sea level; dv: vertebrate deposit (not in scale) (from carboni & lecca, 1995, modified). mimomys pitymyoides janossy & meulen are associated in several late villanyian faunas (see discussion in: marcolini, 2001) while all the three species m. ostramosensis, m. pitymyoides and m. pusillus (méhély) have been recently recovered together in some late villanyian localities (i.e. przymilowice 3, poland) (nadachowski, 2001). if we consider this piece of information, together with large mammals biochronological information the assemblage can be correlated with the costa s. giacomo to olivola f.u., late pliocene in age (marcolini, in press). on the basis of the fossil content, the basal portion of the massarella unit and the “conglomerati di vinci” must be attributed to the late pliocene (marcolini, 2001; in press), in accordance to the recent interpretation of the lower valdarno area suggested by zanchetta et al. (1995), zanchetta & mazza (1996) and marcolini et al. (2000). these authors suggest that the post-middle 17italian plio-pleistocene mammal biochronology ... pliocene cycle in the lower valdarno is not entirely attributable to the early pleistocene but it could be antedated to the late pliocene. indeed, zanchetta & mazza (1996), on the basis of the finding of anancus arvernensis (croizet & jobert) in sediments disconformably overlying the sabbie gialle fm. and laterally continuous with the sabbie e argille ad arctica islandica fm., suggest that the lowermost part of this new cycle may be older than the base of the early pleistocene. the authors suggested two scenarios to justify this finding: the first hypothesis is that anancus arvernensis, whose lad in italy is in the costa san giacomo f.u., survived until the pleistocene olivola f.u. (now correlated with late pliocene; torre et al., 1996). the second one is that the base of the sabbie e argille ad arctica cycle is older than previously believed, i.e. late pliocene. the authors saw the second scenario as the most acceptable. fig. 2 location of the lower valdarno fossiliferous sites and schematic sketch of the relationships of the left-hand and right-hand plio-pleistocene deposits. 33)) tthhee ssoouutthh--wweesstteerrnn bbrraanncchh ooff tthhee ttiibbeerr rriivveerr bbaassiinn ((uummbbrriiaa)):: aann ooppeenn aaiirr llaabb ffoorr ccoorrrreellaattiinngg ccoonnttiinneennttaall ttoo mmaarriinnee ddeeppoossiittss the tiber river basin is the largest intramontane basin of the apennine, in which non marine sedimentation took place from pliocene up to holocene. modern studies give an updated picture of stratigraphy and palaeontology of its southwestern branch, where the sedimentary successions widely crop out. stratigraphy was depicted, among others, by conti & girotti (1978), ambrosetti et al. (1989, 1995a, 1995b), basilici (1995, 1997), abbazzi et al. (1997). the pliocene and early pleistocene deposits considered in these studies are referable to three lithostratigraphic units (fig. 3): 1. the “fosso bianco” formation, a lacustrine unit, middle pliocene – late pliocene in age. 2. the “s. maria di ciciliano” formation, which unconformably lies above the “fosso bianco” formation. it consists of sediments laid down in a fluvial environment characterised by different facies: meandering channel deposits with trough cross stratification, lake and swamp deposits, and paleosols. this formation has been referred to the early pleistocene but, as discussed in this work, the palaeontological data suggest the occurrence of late pliocene elements. 2. the “chiani-tevere formation”, a marine unit widely outcropping along the middle tiber valley and bordering on the “s. maria di 18 ciciliano” formation by means of the interfingering of their sediments. the “chiani-tevere” formation is mostly early pleistocene, with only in a few sites a gelasian age. the total thickness exceeds 300 m and the heteropy to the “s. maria di ciciliano” formation occurs where its strata are santernian in age (mancini et al., in press). up to 15 years ago the only important large mammal finding in the south-western branch of the tiber river basin was the almost complete skeleton of stephanorhinus etruscus (falconer) coming from capitone (ambrosetti, 1972). in the following years a new research campaign enabled a more detailed definition of the stratigraphy of continental deposits outcropping in the area as well as the discovery of many vertebrate sites. in the area near terni and montecastrilli the “s. maria di ciciliano” formation outcrop (basilici, 1995; 1997). this formation is heteropic to the marine chianitevere formation, which is mostly of santernian age (mancini et al. in press), thus it has traditionally be referred to early pleistocene. recent discoveries in the terni area suggest the occurrence of more fossiliferous levels different in composition and age. in the fluvial deposits exposed in this area three mammal faunal assemblages have been collected until now. the older one comes from torre picchio and includes a great number of vertebrates, coprolites, freshwater molluscs, ostracods and plants (woods, fruits and seeds) (girotti et al., in press). vertebrates are represented by large and small mammals, rare birds, reptiles, amphibians and some fishes. among the mammals prolagus sp. oryctolagus lacosti (pomel), mimomys medasensis michaux, ?mammuthus meridionalis (nesti), stephanorhinus cf. s. etruscus (falconer), equus stenonis cocchi, sus strozzii meneghini, eucladoceros dicranios (nesti) vel ctenoides (nesti), axis nestii (major), bovoidea (?gallogoral sp.), leptobos vallisarni merla vel l. etruscus (falconer), mustelidae indet. (?baranogale sp.), canis cf. c. arnensis del campana, ?homotherium crenatidens (fabrini) have been found. this faunal assemblage shows transitional features between costa s. giacomo f.u. and olivola f.u., with the contemporary occurrence of mimomys medasensis (recorded herein for the first time outside spain), ?baranogale sp. (similar in size with the middle villafranchian european specimens), ?gallogoral sp., axis nestii and leptobos etruscus. another faunal assemblage comes from villa s. faustino and colle s. andrea, near massa martana (ambrosetti et al., 1995a) and it is referable to the late villafranchian. at villa s. faustino the fossil mammals mainly come from the sandy deposits (ambrosetti et al., 1995; sardella et al., 1995) and include: castor sp., elephantidae indet., stephanorhinus etruscus, equus stenonis, sus strozzii, axis nestii, cervidae indet., leptobos sp. (vallisarni vel etruscus), megantereon cultridens (cuvier, partim). at colle s. andrea pachycrocuta cf. p. brevirostris (aymard) cervidae indet., leptobos cf. l. vallisarni, castor sp. occur. the paleontological analysis of these sites suggests they are coeval and to refer the faunas to the tasso f.u. the third assemblage comes from colle s. umano and includes large mammals referable to the late villafranchian-earliest galerian (early pleistocene). the faunal list includes a large sized equid referable to equus ex gr. e. bressanus-suessenbornensis, a bovid with bisontine features (bison vel leptobos), hippopotamus antiquus desmarest and axis eurygonos (azzaroli). the presence of different mammal faunas in the south-western branch of the tiber river basin suggests a more complex framework for the stratigraphy of the “s. maria di ciciliano” formation. the faunal assemblage coming from torre picchio shows more “archaic” features (mimomys medasensis, axis nestii, the possible r. sardella et al. fig. 3 location of the tiber river basin and schematic sketch of the stratigraphy: fa acquasparta formation (early pleistocene); 4, fsmc s. maria di ciciliano formation (early pleistocene-?late pliocene); fpn ponte naia formation (late pliocene); ffb fosso bianco formation (middle-late pliocene); ps pre-pliocene substratum. 19 occurrence of a middle sized bovid) compared to that from colle s. umano (axis eurygonos, large bison-like bovid, etc…), with typical early pleistocene elements. biochronological considerations suggest a wider time span for the continental succession of “s. maria di ciciliano” formation (late pliocene-early pleistocene). the biochronology of this faunal assemblages and its significance in the stratigraphy of the tiber river basin is discussed in detail in girotti et al. (in press), where two possibilities have been pointed out: to assign a late pliocene age to the fossiliferous deposit, with the first occurrence of species that will be very common during the early pleistocene times (e.g. axis nestii, leptobos etruscus) or to consider peninsular italy as a refugium area, in which some vertebrates, molluscs and plants of pliocene origin survived in the early pleistocene (see conclusions). ccoonncclluussiioonnss the use of the biochronological units, based on the occurrence and evolutionary degree of mammals, for the correlation of marine and continental sequences, in some cases enables a more detailed definition of the age of the sequences, but in other cases shows a more complex framework. the mandriola fossiliferous site is an emblematic example of how biochronological criteria can be successfully used to infer age determination. moreover, in this case it has been possible to apply continental european biochronological framework to the study of insular faunas. the interpretation of the marine and non marine fossil record of lower valdarno and tiber river basin (related to the plio-pleistocene transition) lead to two different scenarios: 1) the italian peninsula can be considered as a refugium area for the pliocene taxa, which survived until the earliest pleistocene; 2) the age of deposits previously referred to early pleistocene has to be considered older (late pliocene). the latter interpretation fits well with the stratigraphy of the right-hand side of the lower valdarno and of the upper valdarno and also with the palaeomagnetic analyses of ambrosetti et al. (1975) and bedini et al. (1981) recognising the subchron reunion (2-2.2 ma) within the sediments of the “sabbie e argille ad arctica“ of the colline pisane. moreover, this interpretation is confirmed by our recent findings of vinci and casa sgherri that enable a correlation of the “conglomerati di vinci” and the massarella unit with the “sabbie e argille ad arctica”, since all of them bear mammals of the costa san giacomo-olivola f.u. the mammal faunas from the south-western branch of the tiber river basin show differences in composition and can be referred to costa s. giacomoolivola f.u. (torre picchio), tasso f.u. (villa s. faustino-colle s. andrea) and farneta f.u. (colle s. umano) respectively. such palaeontological data suggest a wider time span (late pliocene-early pleistocene) for the continental “s. maria di ciciliano” formation. an age attribution for this formation other than early pleistocene is therefore problematic, both from a geologic and a stratigraphic point of view. from the geological point of view, the “s. maria di ciciliano” formation is heteropic to the marine chiani tevere one, which is prevailingly santernian in age and lies unconformably on the middle pliocene cycle: only in some areas of structural lowering it passes inferiorly and continuously to late pliocene strata, but before the heteropic episodes. in order to find a solution to these still open problems a detailed analysis of the stratigraphy, of the local tectonics of the fossiliferous marine and non marine deposits, and the taphonomy of the mammal remains has to be considered. aakknnoowwlleeddggeemmeennttss we wish to thank two anonymous referees for their critical comments on the manuscript, t. kotsakis, o. girotti and m. mancini for the useful discussions and the suggestions. this work is supported by igag (istituto di geologia ambientale e geoingegneria) c.n.r. rreeffeerreenncceess abbazzi l., albianelli a., ambrosetti p., argenti p., basilici g., bertini a., gentili s., masini f., napoleone g. & pontini m.r. 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(1978) il villafranchiano nel “lago tiberino”, ramo sud-occidentale: schema stratigrafico e tettonico. geol. romana, 1166, 67-80. esu d. & kotsakis t. (1985) les vertébrés et les mollusques continentaux du tertiaire de la sardaigne: paléobiogéographie et biostratigraphie. geol. romana, 2222 (1983), 177-206. esu d. (1986) la malacofauna continentale pliocenica di mandriola (sardegna occidentale): sistematica e paleobiogeografia. geol. romana, 2222 (1983): 2350. esu d. (1999) contribution to the knowledge of neogeneclimatic changes in western and central europe by means of non-marine mollusques. in: agustí j., rook l. & andrews p. (eds.). evolution of neogene terrestrial ecosystems in europe: 328-354, cambridge university press, cambridge. fejfar o. (2001) the arvicolids from arondelli-triversa: a new look. boll. soc. pal. it., 4400, 185-193. girotti o., capasso barbato l., esu d., gliozzi e., kotsakis a., martinetto e., petronio c., sardella r. & squazzini e. (in press) the section of torre picchio (terni, umbria, central italy): a villafranchian site rich in vertebrates, molluscs, ostracods and plants. riv. ital. paleont. strat. gliozzi e., abbazzi l., argenti p., azzaroli a., caloi l., capasso barbato l., di stefano g., esu d., ficcarelli g., girotti o., kotsakis t., masini f., mazza p., mezzabotta c., palombo m.r., petronio c., rook l., sala b., sardella r., zanalda e. & torre d. (1997) biochronology of selected mammals, molluscs and ostracods from the middle pliocene to the late pleistocene in italy. the state of the art. riv. ital. paleont. strat., 110033, 369-388. lópez martínez n. & thaler l. (1975) biogéographie, évolution et compléments à la systématique du groupe d’ochotonides piezodus-prolagus (mammalia, lagomorpha). bull. de la soc. géol. fr., s. 7, 1177 , 850-866. mancini m., cavinato g.p. & girotti o. (in press) il quaternario della media valle del tevere. mem. soc. geol. ital. marcolini, f. (2001) continental lower valdarno rodent biochronology and two new methods for the systematics of mimomys (arvicolidae, rodentia). thesis, pisa university: 133 pp. marcolini (in press) continental lower valdarno rodent biochronology and two new methods for the systematics of mimomys (arvicolidae, rodentia). atti soc. tosc. sci. nat., ser a marcolini, f., bonadonna, f.p., kotsakis, t., mazza, p. & zanchetta, g. (2000) preliminary data on the microand macromammal remains from casa sgherri, lower valdarno (tuscany, central italy). boll. soc. pal. it., 3399, 243-252. mein p. & michaux j. (1970) un nouveau stade dans l’évolution des rongeurs pliocènes de l’europe sud-occidentale. comptes rendu de l’academie de sciences paris, s. d, 222200, 2780-2783. nadachowski a. (2001) new important neogene and pleistocene mammal assemblages from poland. boll. soc. pal. it., 4400, 243-248. pecorini g., rage j.-c. & thaler l. (1974) la formation continentale de capo mannu, sa faune de vertébrés pliocènes et la question du messinien en sardaigne. rendiconti dei seminari della facoltà di scienze dell’università di cagliari, 4433 (1973) (suppl.), 305-319 . sardella r., di stefano g. & petronio c. (1995) the villafranchian mammal faunas from the tiber river basin (umbria, central italy). il quaternario, 88, 509-514. torre, d., albianelli, a., bertini, a., ficcarelli, g., masini, f., napoleone, g. (1996) paleomagnetic calibration of plio-pleistocene mammal localities in central italy. in: neogene and quaternary mammals of the palearctic, nadachowski a. & werdelin l. (eds.), acta zool. cracov., 3399, 559-570. zanchetta, g. & mazza, p. (1996) anancus arvernensis remains from the basal portion of the arctica islandica bearing marine deposits of lower valdarno. boll. soc. geol. it., 111155, 105-113 . zanchetta, g., petrucci, s., mazza, p. & rustioni, m. (1995) new villafranchian finds from the lower valdarno. il quaternario, 88, 449-456. r. sardella et al. ms. ricevuto il 20 ottobre 2002 testo definitivo ricevuto il 17 febbraio 2003 ms. received: october 20, 2002 final text received: february 17, 2003 imp. bellucci & sseeggnnaallaazziioonnee ddii nnuuoovvii ddeeppoossiittii ppiirrooccllaassttiiccii iinntteerrccaallaattii aallllee ssuucccceessssiioonnii ccoonnttiinneennttaallii ddeell pplleeiissttoocceennee ssuuppeerriioorree--oolloocceennee ddeellllaa ppoorrzziioonnee nnoorrdd--oorriieennttaallee ddeellllaa ppiiaannaa ccaammppaannaa ffrraanncceessccaa bbeelllluuccccii11,, nniiccoolleettttaa ssaannttaannggeelloo22,, aannttoonniioo ssaannttoo33 1dipartimento di geofisica e vulcanologia, università di napoli “federico ii” 2dipartimento di scienze della terra, università di napoli “federico ii” 3dipartimento di ingegneria geotecnica -sezione di geologia applicatauniversità di napoli “federico ii” riassunto in questa nota vengono segnalati nuovi affioramenti di depositi piroclastici da caduta e da flusso rinvenuti lungo il margine nord-orientale della piana campana ed intercalati a formazioni clastiche tardo quaternarie. i dati raccolti si riferiscono a depositi vulcanoclastici rinvenuti sia al letto che al tetto della formazione dell’ “ignimbrite campana” (ic) e da essa chiaramente separati e distinti per la presenza di paleosuoli, depositi fluviali e/o di superfici di erosione. in particolare sono stati riconosciuti due importanti eventi eruttivi pre-ic: il più antico è costituito da livelli di pomici da caduta clinostratificate al piede dei versanti carbonatici e caratterizzati da pomici bianco-grigiastre con diametro medio di 0,5 cm e spessore di circa 50 cm. su questi livelli da caduta poggia, con chiaro contatto erosionale, un pumice flow di colore giallastro che presenta spessori variabile tra i 2 e 6 metri. gli affioramenti più significativi sono localizzati nei dintorni di maddaloni e di durazzano ed in entrambe le località, il pumice flow giallastro è ricoperto dalla formazione dell’i c. in aree più interne rispetto alla piana campana, precisamente nella zona di solopaca, sono stati rilevati altri limitati affioramenti di piroclastiti antiche, costituite da alcuni metri di cineriti e pomici grigio nerastre molto alterate e fortemente cementate su cui poggiano depositi di conoide terrazzati, ricoperti lateralmente dai depositi dell’ ic. al tetto dell’ic, e da essa separato per la presenza di un paleosuolo o di depositi fluviali interposti, abbiamo rinvenuto in tutta l’area investigata un altro livello piroclastico da caduta caratterizzato dalla alternanza di cineriti bianche stratificate e livelli pomicei biancastri con spessore totale variabile tra i 50 cm ed i 200 cm. i dati stratigrafici raccolti, oltre a fornire preziose informazioni sull’attività eruttiva tardo pleistocenica dell’ area della piana campana, potranno in futuro contribuire a identificare nuovi livelli marker per la stratigrafia dei depositi tardo quaternari del margine tirrenico campano. abstract the main aim of this paper is to signal some new outcrops of pyroclastic deposits along the northern rim of the campanian plain, (province of caserta); the study refers particularly to pyroclastic successions located both at the base and at the bottom of the “ignimbrite campana” (ic), the most widespread volcanic formation in the area. the oldest deposits in the area have been found near the solopaca village, at the northern sector of the studied area; they are made up by alternating black and grey pumiceous levels some meters thick, and are covered by poligenic conglomerates of alluvial fan that can be chronologically ascribed to the end of middle pleistocene. in the surroundings of maddaloni and durazzano however, the deposits standing below the ic formation are characterized by the presence of two distinct pyroclastic units. the oldest one is represented by a pyroclastic fall deposit, at least 50 cm thick, included within slope or alluvial fan deposits. the youngest is made up by a yellow pumices flow with a thickness variable between 2 and 10 m, which always covers with erosional contact, the above described slope or alluvial fan deposits. at the top of ic formation another important pyroclastic level has been found all over the studied area. it is made up by white layered ash fall deposits covered by a massive, yellowish pumiceous level and its total thickness range is from 0,5 to 1 meter. all these new outcrops have been sampled for sedimentological, chemical and petrographical analysis that are still in progress, in order to identify their origin and to better define their chronological and stratigraphical position within the complex volcanic history of the campania plain. parole chiave: depositi piroclastici; pleistocene superiore; pianura campana; appennino meridionale. keywords: pyroclastic deposits; upper pleistocene; campanian plain; southern appenines il quaternario italian journal of quaternary sciences 1166(2), 2003, 279-287 11.. iinnttrroodduuzziioonnee in questa nota vengono segnalati nuovi affioramenti di depositi piroclastici da caduta e da flusso rinvenuti lungo il margine nord-orientale della piana campana, durante il rilevamento del nuovo foglio “caserta est” della nuova carta geologica d’italia in scala 1:50.000 (progetto carg). in quest’area la formazione quaternaria affiorante più diffusa è senz’altro rappresentata dall’ “ignimbrite campana” (ic) che costituisce una coltre con spessore variabile tra i 30 ed i 50 metri (barberi et al., 1978; di girolamo, 1968; di girolamo et al., 1973; 1984) e la cui messa in posto è avvenuta circa 39 ka (de vivo et al., 2001). i dati raccolti si riferiscono a depositi vulcanoclastici (fig. 1) rinvenuti sia al letto che al tetto di questa importante formazione vulcanica e da essa chiaramente separati e distinti per la presenza di paleosuoli, depositi fluviali e/o di superfici di erosione. tali depositi non erano segnalati nella precedente cartografia geologica ufficiale. 280 f. bellucci, n. santangelo & a. santo 22.. iill qquuaaddrroo ggeeoollooggiiccoo ee ggeeoommoorrffoollooggiiccoo numerosi sono i lavori che si sono occupati della ricostruzione della stratigrafia del sottosuolo della piana campana e della sua evoluzione durante il quaternario (d’erasmo, 1931; ippolito et al., 1973; aprile & ortolani, 1978; brancaccio et al., 1991; 1994; romano et al., 1994; aprile & toccaceli, 2002). romano et ali. (1994) hanno effettuato una ricostruzione dettagliata della stratigrafia superficiale (primi 200 metri) della piana evidenziando la presenza di sei unità stratigrafiche di ambiente variabile tra marino, transizionale e continentale, di età compresa tra il pleistocene medio-superiore e l’olocene. essi stabiliscono che l’intera pianura è stata subsidente durante la prima metà del pleistocene superiore, consentendo il permanere di un ambiente di sedimentazione marino nonostante l’intensa attività piroclastica registrata verso la fine di questo intervallo. nella seconda metà del pleistocene superiore invece viene registrata una netta diminuzione della subsidenza che, in coincidenza con l’oscillazione eustatica negativa dello stadio isotopico 2, ha consentito l’emersione definitiva dell’area. la morfologia dei settori perimetrali della piana campana è fortemente condizionata dalla presenza della formazione dell’ ic una imponente coltre piroclastica da flusso con spessori variabili tra i 30 ed i 50 metri che ha colmato tutte le depressioni morfologiche preesistenti (strutturali e incisioni fluviali) e creato un vasto plateau deposizionale. questa estesa formazione vulcanica, datata dapprima 37 ka (deino et al., 1994) e successivamente 39 ka (de vivo et al., 2001), rappresenta un importante marker stratigrafico avendo un vastissimo areale di affioramento (circa 3800km2) ed essendo facilmente riconoscibile sia in affioramento che da dati di sondaggio per le sue particolari caratteristiche litologiche. sebbene numerosi studi indichino i campi flegrei come centro di emissione di questa grande eruzione (barberi et al., 1991; fisher et al., 1993; orsi et al., 1999; rosi et al., 1999; ort et al., 1999) recenti indagini (rolandi et al., 2003) contraddicono questo modello e rivalutano l’ipotesi , già avanzata in passato (di girolamo, 1968; 1978; di girolamo et al., 1984; barberi et al., 1978) di un’eruzione fissurale lungo sistemi di fratture parallele alle faglie peritirreniche che bordano la piana campana. la presenza di questa potente coltre ignimbritica ha obliterato gli affioramenti di depositi quaternari più antichi che sono molto limitati e concentrati nei settori bordieri della piana. romano et al. (1994) segnalano la presenza di depositi marini e vulcanoclastici sottostanti all’ic nei dintorni di maddaloni e cancello e, sulla base di stratigrafie di sondaggi, in tutto il sottosuolo della piana. de vivo et al. (2001) segnalano la presenza di deposti piroclastici ed ignimbritici datati tra 157 e 205 ka nei dintorni di taurano, lungo il margine orientale della piana. aprile & toccaceli (2002) segnalano la presenza nel sottosuolo della piana del sarno di una formazione ignimbritica sottostante all’ic e la correlano con l’ignimbrite di taurano di de vivo et al., 2001. rolandi et al. (2003) inoltre indicano la presenza di altri depositi ignimbritici antichi in varie località bordiere della piana (penisola sorrentina e monti di caserta) e li datano rispettivamente a 245 ka, 289 ka (ignimbriti di seiano) e 116 ka (ignimbrite di durazzano). per quanto concerne i depositi successivi alla messa in posto dell’ic, essi sono costituiti da depositi continentali alluvionali e di versante, rappresentati prevalentemente da depositi piroclastici rimaneggiati, cui sono intercalati e/o sovrapposti depositi piroclastici da caduta. in particolare nella zona di nostro interesse (fig. 1) di girolamo (1968) segnala la presenza di piroclastiti stratificate costituite da alternanze di livelli cineritici e pomicei poggianti su un paleosuolo a tetto dell’ic, in tutta l’area a sud di caserta ( s.nicola la strada, s.marco evangelista e maddaloni) e, a ne di caserta, nella valle di maddaloni, ricostruendone l’andamento degli spessori che aumentano verso sud. cole & scarpati (1993) segnalano la presenza di depositi piroclastici da caduta più recenti dell’ic, oltre che nelle stesse aree individuate da di girolamo (1968), anche a no di caserta presso s. angelo in formis. entrambi gli autori interpretano questi depositi come i prodotti distali della formazione tufo giallo napoletano datata 12 ka (alessio et fig. 1 ubicazione degli affioramenti studiati: 1) affioramenti delle piroclastiti post ignimbrite campana; 2) affioramenti delle piroclastiti pre ignimbrite campana. location map of the studied outcrops. 1) outcrops of post campanian ignimbrite pyroclastic deposits; 2) outcrops of pre ic piroclastic deposits. al., 1971; 1973; rosi & sbrana,1987; scandone et al.,1991). inoltre, nella zona immediatamente a sud dell’area in studio, nei dintorni di giugliano, viene segnalata la presenza di un deposito da flusso piroclastico (“tufo di giugliano”) datato 18 ka da de vivo et al. (2001) e 23 ka da rolandi et al., (2003). tale deposito risulta caratterizzato da un’alternanza di livelli cineritico sabbiosi a struttura massiva intercalati da livelli pomicei da caduta, presenta alla base un paleosuolo ed è sovrapposto all’ic. 33.. ii lliivveellllii pprree--iicc gli affioramenti più significativi sono localizzati nei dintorni di maddaloni, durazzano e solopaca e sono intercalati a successioni continentali tardo pleistoceniche riconducibili a detriti di versante, antichi conoidi alluvionali e depositi fluvio-palustri. le descrizioni stratigrafiche e le sezioni geologiche sono state realizzate spesso grazie a tagli “freschi” legati alla coltivazione di alcune cave. 33..11.. llooccaalliittàà ccaarrmmiiaannoo –– mmaaddddaalloonnii lungo il bordo sud-occidentale dei monti di durazzano, in località “carmiano”, nei pressi del cimitero di maddaloni, è possibile osservare la sovrapposizione stratigrafica dell’ic su prodotti piroclastici più antichi. questo importante affioramento è emerso grazie ai lavori di scavo di una cava ed era già stato segnalato in romano et al. (1994). in particolare tali autori evidenziavano la presenza di pomici e cineriti antiche preic, senza però soffermarsi sugli aspetti stratigrafici di dettaglio. i lavori di scavo ed i movimenti di terra nella cava hanno quasi del tutto obliterato l’affioramento segnalato in romano et al. (1994) aprendone comunque altri ugualmente significativi. nella fig. 2 è riportata la situazione alla cava al 1994; dalla foto è possibile vedere con chiarezza che al di sotto dell’ dell’ic (d), sono presenti circa 10 m di piroclastiti sciolte pre-ic (b e c), poggianti a loro volta sul substrato carbonatico (a). i sopralluoghi successivi hanno permesso di descrivere nel dettaglio le formazioni vulcaniche pre ic; esse poggiano con angoli di circa 25° su brecce calcaree a matrice sabbiosa arrossata che ricoprono il substrato carbonatico. al contatto tra le brecce e le piroclastiti sovrastanti è presente un paleosuolo conservato in sacche. l’analisi delle caratteristiche litologiche, sedimentologiche e tessiturali delle piroclastiti ha permesso di distin281segnalazione di nuovi depositi piroclastici ... guere, dal basso, le seguenti unità (fig. 3): uunniittàà ppoommiicceeaa ddaa ccaadduuttaa: è costituita da una successione di circa 2 m di pomici. questa successione è distinta dal basso in: un livello di cenere fine ricca in cristalli sciolti con spessore di 8 cm; un livello di circa 40 cm di pomici da caduta grigio fig. 2 affioramento delle piroclastiti pre ignimbrite campana (da romano et al., 1994) nella cava abbandonata di maddaloni. a) calcari mesozoici e brecce di versante; b) unità pomicea pre ignimbrite campana; c) pomici rimaneggiate; d) ignimbrite campana. outcrop of pre campanian ignimbrite pyroclastic deposits (from romano et al., 1994) in the abandoned quarry near maddaloni. a) mesozoic limestones and slope breccia; b) pre campanian ignimbrite pumiceous unit; c) reworked pumiceous levels; d) campanian ignimbrite. fig. 3 colonna stratigrafica di sintesi dei terreni affioranti nella cava abbandonata di maddaloni. synthetic stratigraphic column of pre campanian ignimbrite pyroclastic deposits cropping out in the abandoned quarry near maddaloni. 282 avana con debole gradazione inversa (fig. 4); il diametro delle pomici a spigoli vivi è mediamente di circa 1,5 cm, con un massimo di 3 cm; alternanze di livelli pomicei e livelli cineritici (spessore 1,5 m) risedimentati lungo il versante a spese della sottostante unità pomicea da caduta. uunniittàà ddaa fflluussssoo (fig. 5): questa unità poggia con un chiaro contatto erosionale sulle pomici basali; è costituita da un deposito piroclastico a struttura massiva in cui la matrice pomicea e sabbiosa assume una colorazione giallastro – rossastra, al suo interno sono diffuse pomici grigie non alterate e subarrotondate di dimensioni variabili, mediamente centimetriche e spesso raggruppate in sciami. le caratteristiche tessiturali del deposito indicano un meccanismo di messa in posto da flusso piroclastico. il suo spessore è variabile (in questa località da 2 a 4m) e la parte sommitale è parzialmente pedogenizzata. l’unità da flusso è a sua volta ricoperta da circa 1,5 metri di depositi piroclastici da caduta alternati a livelli pomicei rimaneggiati che, nella parte alta, sono ricoperti da un deposito prevalentemente vulcanoclastico, con intercalazioni di lenti di clasti carbonatici decimetrici a spigoli vivi, pedogenizzato al tetto. iiggnniimmbbrriittee ccaammppaannaa: al tetto di questi deposti (fig. 2) si rinviene un tufo grigio a scorie grigie con fratturazione colonnare appartenente alla ben nota formazione vulcanica campana; lo spessore diminuisce dalla piana verso il versante passando da circa 15m a circa 50 cm. 33..22.. llooccaalliittàà ffoorrcchhiiaa --dduurraazzzzaannoo lungo la strada che da forchia conduce a durazzano è possibile notare in diversi punti di affioramento un deposito piroclastico, di circa 8m di spessore a tessitura massiva, compatto ma non litoide, costituito da una matrice a granulometria sabbiosa, sabbiosoghiaiosa, arrossata o giallastra e da inclusi pomicei di colore avana, sub-arrotondati presenti in maniera diffusa e spesso in lenti. queste caratteristiche permettono di definirlo come un flusso piroclastico pomiceo la cui messa in posto è stata guidata dalla morfologia preesistente. si rinviene nella porzione sud-occidentale della piana di durazzano e lungo la strada che da forchia sale alla sella di durazzano, localmente ricoperto da depositi colluviali al cui interno si rinvengono clasti calcarei grossolani, frammenti ceramici di età romana e scorie di scarto della lavorazione del ferro. un affioramento molto significativo è localizzato nella piana di durazzano. qui è chiara la sovrapposizione dei prodotti dell’ic sui prodotti del flusso pomiceo prima descritto (fig. 6). le due formazioni vulcaniche vengono a contatto bruscamente lungo una superficie di erosione e presentano caratteristiche litologiche molto diverse. il deposito tufaceo inferiore ha una colorazione giallo rossastra, è prevalentemente pomiceo e, pur essendo compatto, non presenta fenomeni di litificazione secondaria; il deposito tufaceo superiore (ic), invece, ha una tipica colorazione grigiastra è ricco in frammenti scoriacei e presenta un aspetto litoide; quest’ultima caratteristica è osservabile meglio negli affioramenti presenti più a valle nel paese di durazzano dove l’ic assume anche la tipica fratturazione colonnare. fig. 4 particolare dell’unità pomicea da caduta nella cava abbandonata di maddaloni. a) livelli di pomici da caduta in posto; b) alternanze di livelli di pomici rimaneggiate. detail of the fall pumiceous unit in the abandoned quarry near maddaloni. a) fall pumiceous unit; b) reworked pumiceous levels. fig. 5 cava abbandonata di maddaloni: l’unità da flusso (b) poggia con contatto erosionale sull’unità pomicea (a). abandoned quarry near maddaloni: erosional contact between flow unit (b) and fall pumiceous unit. f. bellucci, n. santangelo & a. santo 283 33..33 ppiiaannaa ddii dduurraazzzzaannoo:: llooccaalliittàà mmaasssseerriiaa mmeelllliinnoo in questa località la serie piroclastica è caratterizzata da depositi da caduta e da flusso in posto, inseriti in una successione di depositi piroclastici rimaneggiati prevalentemente pomicei, con granulometria da cineritico-sabbiosa a ghiaiosa, che definiscono una conoide alluvionale (fig. 7). la base di questa successione alluvionale non è affiorante e lo spessore minimo stimabile è di almeno 20 metri. gli affioramenti sono tutti localizzati all’interno di una cava dove è stato possibile riconoscere le seguenti unità piroclastiche in posto: uunniittàà ppoommiicceeaa ddaa ccaadduuttaa e’ costituita da 70 cm di pomici da caduta biancastre, a spigoli vivi, vacuolari, vetrose con dimensioni fino 5 cm di diametro; scarsa la presenza di litici, con diametro massimo di 2 cm. (a in fig. 8). queste pomici poggiano su un deposito massivo a matrice cineritica con pomici sub-arrotondate e litici più piccoli di quelli del deposito da caduta (0,5 cm); lo spessore è variabile (circa 15 cm), la giacitura è conforme alle pomici soprastanti ed ha un’inclinazione di circa 40°. alle pomici da caduta indisturbate, seguono verso l’alto, per circa 2m, alternanze di livelli cineritici e pomicei costituiti dai materiali del livello da caduta risedimentati in ambiente alluvionale. uunniittàà ddaa fflluussssoo questa unità si rinviene intercalata nei depositi di conoide con spessori e giacitura diverse in funzione delle geometrie dei depositi sottostanti e del grado di erosione subito dopo la sua messa in posto. in un piazzale più basso della cava (fig. 9) è possibile notare come tale unità si inserisce ai margini della conoide assumendo una giacitura suborizzontale con spessori a vista maggiori di 2 m; a tetto presenta altri 3 m di piroclastiti rimaneggiate in ambiente alluvionale. chiudono la successione stratigrafica dell’area un paio di metri di piroclastiti pedogenizzate brunastre. la base di questa unità è costituita da un livello pomiceo-cineritico, biancastro compatto con uno spessore di circa 15 cm; la tessitura è massiva la matrice è sabbiosa avana rosata e le pomici sono di colore grigio avana di dimensioni mediamente centimetriche. verso la parte alta del deposito sono presenti pomici di dimensioni maggiori (fino a 4,5 cm) vacuolari, a volte vetrose con fenocristalli chiari e scuri; è scarsa la presenza di litici tra i quali sono frequenti clasti di tufo marrone scuro con dimensioni di circa 1 cm. le caratteristiche tessiturali di questa unità sono quelle di un flusso piroclastico pomiceo. 33..44.. llooccaalliittàà ssoollooppaaccaa in aree più interne rispetto alla piana campana, precisamente nella zona di solopaca, sono stati rilevati altri limitati affioramenti di piroclastiti antiche non segnalate in fig. 8 località “masseria mellino” a durazzano: l’unità pomicea da caduta in posto (a) e rimaneggiata (a’) e l’unità da flusso (b) intercalate ai depositi piroclastici rimaneggiati in ambiente di conoide (c). masseria mellino locality, durazzano: fall pumiceous unit (a), reworked pumiceous unit (a’) and flow unit (b) interbedded within alluvial fan deposits. fig. 6 la sovrapposizione dell’ ignimbrite campana (b) sui prodotti dell’unità da flusso (a) nella piana di durazzano. the campanian ignimbrite (b) lying on the flow unit (a) near durazzano village. fig. 7 sezione geologica schematica dei depositi piroclastici pre ignimbrite campana affioranti nei dintorni di durazzano. 1) ghiaie e sabbie vulcanoclastiche di ambiente di conoide alluvionale; 2) ignimbrite campana; 3) unità da flusso; 4) unità pomicea da caduta; 5) calcari mesozoici; 6) faglia. geological cross section in the precampanian ignimbrite pyroclastic deposits cropping out near durazzano. 1) volcanoclastic gravel and sands of alluvial fan; 2)ic; 3) flow unit; 4) fall pumiceous unit; 5) mesozoic limestones; 6) fault. segnalazione di nuovi depositi piroclastici ... 284 letteratura. il più significativo è quello di località “ferri” in sinistra orografica del f. calore dove le piroclastici antiche poggiano su argille e sabbie di ambiente fluvio-palustre e sono caratterizzate da ripetute alternanze di livelli pomicei bianchi e grigi e di livelli cineritici, nell’insieme fortemente cementati e a consistenza tufacea (fig. 10). i livelli di pomici presentano gradazioni sia inverse che dirette, le pomici hanno dimensioni variabili dai 2 ai 5 mm, si presentano molto alterate e sovente contengono litici; lo spessore totale è di circa 2 m. al tetto di questi depositi si rinviene una successione di conglomerati di conoide alluvionale cui sono associate delle superfici terrazzate intorno ai 100 m s.l.m.; tali conglomerati vengono attribuiti in letteratura al tardo pleistocene medio (iacobacci et al., 1959). sia i conglomerati che le piroclastici antiche risultano ricoperte lateralmente dalla formazione dell’ic il cui top deposizionale costituisce una superficie terrazzata intorno ai 55 m s.l.m. (fig.11). 44.. ii lliivveellllii ppoosstt--iicc al tetto pedogenizzato dell’ic, o su sedimenti alluvionali che la ricoprono, abbiamo rinvenuto in tutta l’area investigata altri depositi piroclastici da caduta non distinti nella precedente cartografia geologica ufficiale del foglio 172 “caserta”. essi affiorano prevalentemente al top di superfici terrazzate (loc. limatola, dugenta) hanno uno spessore complessivo variabile dai 50 ai 200 cm e presentano quasi sempre nella parte bassa cineriti bianche e grigie, fittemente laminate, con intercalazioni di livelli pomicei bianchi. nella parte alta invece si rinviene costantemente un livello di cineriti giallastre, massive con pomici sparse aventi uno spessore di circa 60 cm (fig. 12). la base spesso poggia su un paleosuolo marrone che si sviluppa a tetto dell’ic o su depositi alluvionali e/o colluviali. tra gli affioramenti più significativi (fig.13), oltre a quello della cava “etep” nei pressi di dugenta, dove al tetto dell’ic si rinvengono delle alluvioni ghiaioso-sabbiose a stratificazione incrociata sormontate da un livello di pomici e poi di cineriti di colore giallastro, va segnalato quello di località “campitello” (ave grazia plena) dove è possibile osservare dal basso stratigrafico1,5 m di cineriti molto fini bianco-giallastre, cui seguono 80 cm di pomici (diametro 2÷3 mm) immerse in una matrice sabbiosa gialla con cristalli idiomorfi di mica e pirosseni. in località “bagno” in sinistra della valle del f. calore è possibile osservare piroclastici molto simili a quelle descritte precedentemente e caratterizzate da alternanze di ceneri e di livelli pomicei. esse sono intercalate a depositi ghiaiosi di ambiente di conoide alluvionale che poggiano chiaramente sulla formazione dell’ic. altri affioramenti significativi sono ubicati nelle numerose cave presenti nei dintorni di caserta, come alla cava di san marco evangelista (fig.14) dove è chiaramente visibile il paleosuolo interposto tra il top dell’ic e questi depositi da caduta riconoscibili anche da fig. 10 i depositi piroclastici pre ignimbrite campana di solopaca. a) argille fluvio-lacustri; b) paleosuolo; c) livelli di pomici grigio scure; d) livelli di pomici grigio chiare. the pre campanian ignimbrite piroclastic deposits cropping out near solopaca. a) fluvio-lacustrine clay; b) paleosoil; c) dark grey pumiceous levels; d) grey pumiceous levels. fig. 9 località “masseria mellino”: unità da flusso (a) ricoperta dai depositi di conoide alluvionale (b) e dal suolo attuale (c). masseria mellino locality, durazzano: the flow unit (a) covered by alluvial fan deposits (b) and present day soil. lontano per la colorazione biancastra e giallastra. la presenza costante in tutti gli affioramenti descritti delle cineriti bianche stratificate passanti ad un livello pomiceo massivo di colore giallastro, lo spessore complessivo poco variabile della successione piroclastica (circa 1÷2 m), la chiara posizione stratigrafica, sicuramente più recente dell’ic, la diffusione areale pressocchè continua tra caserta e solopaca (cfr. fig. 1) fanno ritenere che si tratti sempre dello stesso deposito piroclastico da caduta. f. bellucci, n. santangelo & a. santo queste due ultime unità sono state rinvenute nella medesima posizione stratigrafica e sicuramente sottoposte alla formazione dell’ic. l’unità da flusso in particolare sembra avere una notevole estensione areale e potrebbe includere il “tufo di durazzano” segnalato da rolandi et ali., (2003) e datato 116 ka. per quanto riguarda i depositi post-ic essi rappresentano i prodotti di uno stesso evento eruttivo che ha interessato tutta l’area compresa tra caserta, vallo di maddaloni, limatola, dugenta e solopaca. la parte basale di questi depositi, caratterizzata da alternanze di cineriti bianche e grigie fittemente laminate, presenta elevate analogie sedimentologiche con la parte basale del lower member del tufo giallo napoletano auct. individuato e descritto nei dintorni di caserta (s. angelo in formis) da cole & scarpati (1993) e da wolhetz et al ., (1995). in particolare i livelli cineritici laminati potrebbero essere correlati con l’unità lm1 di wohletz et al. , 1995, mentre risulta più difficoltoso, in assenza di analisi granulometriche, definire una corrispondenza tra le cineriti massive giallastre sovrastanti e gli altri 13 livelli segnalati dagli stessi autori nell’affioramento di s. angelo in formis. in alternativa tali depositi potrebbero essere correlati alle piroclastiti datate 23 ka che trovano corrispondenza con l’ignimbrite di giugliano (de vivo et al ., 2001; rolandi et al., 2003) e con il livello di tephra y3 rinvenuto in carotaggio nel mar tirreno (munno & petrosino, in stampa). in ogni caso è importante segnalare che, in tutta l’area studiata, questi depositi sono gli unici presenti al di sopra dell’ic e che sembrano quindi mancare i prodotti di provenienza flegreovesuviana post-ic segnalati in aree immediatamente a sud est (valle del clanio) da di vito et al., (1998); ciò è ovviamente da imputare ad assi di dispersione differenti. i dati stratigrafici raccolti, oltre a fornire preziose informazioni sull’at285 fig. 11 sezione geologica illustrante i rapporti tra depositi alluvionali e depositi piroclastici nei dintorni di solopaca. 1) alluvioni recenti del f. calore (olocene); 2) ignimbrite campana (39 ka); 3) depositi di conoide alluvionale (pleistocene superiore olocene); 4) depositi fluviali terrazzati (pleistocene mediosuperiore); 5) depositi piroclastici antichi (pleistocene medio?); 6) brecce di versante (pleistocene inferiore-medio) ; 7) calcari mesozoici; 8) faglia. geological cross section showing the relationships between alluvial and pyroclastic deposits near solopaca. 1) recent alluvial deposits of te calore river (holocene; 2) campanian ignimbrite (39 ky); 3) alluvial fan deposits (upper pleistocene holocene); 4) terraced fluvial deposits (middle upper pleistocene); 5) ancient pyroclastic deposits middle pleistocene ?); 6) slope breccias (lower-middle pleistocene); 7) mesozoic limestones; 8) fault. fig.12 località: “ave gratia plena”: particolare dei depositi post ignimbrite campana. a) paleosuolo; b) depositi cineritici biancastri stratificati; c) livello pomiceo massivo di colore giallastro. "ave gratia plena" localit: detail of the post campanian ignimbrite pyroclastic deposits. a) paleosol; b) white layered ash deposits; c) massive and yellowish pumiceous level. 55.. pprroobblleemmii aappeerrttii ee ccoonncclluussiioonnii in tutte le località citate nel testo sono stati prelevati campioni sui quali sono in corso analisi mineralogico-petrografiche e sedimentologiche, per risalire alla paragenesi e quindi alla precisa posizione tefrostratigrafica di queste piroclastiti. pur non avendo ancora risultati sperimentali, sulla base dei soli dati stratigrafici è tuttavia possibile affermare che nell’area esaminata esistono almeno tre formazioni vulcaniche più antiche dell’ ic. esse sono rappresentate dalle pomici antiche di solopaca e dai due livelli denominati, al momento, “unità pomicea da caduta di maddaloni ” e “unità da flusso di durazzano” segnalazione di nuovi depositi piroclastici ... tività eruttiva tardo pleistocenica dell’ area della piana campana potranno, in futuro, contribuire a identificare nuovi livelli marker per la stratigrafia dei depositi continentali e marini tardo quaternari del margine tirrenico campano ed essere correlati ad alcuni dei numerosi livelli piroclastici che si rinvengono normalmente nelle stratigrafie di sondaggi profondi eseguiti in piana campana. llaavvoorrii cciittaattii alessio m., bella f., improta s., belluomini g., calderoni g., cortesi c. & turi f. (1973) university of rome carbon 14 dates x, radiocarbon, 1155 (1), 165. alessio m., bella f., improta s., belluomini g., cortesi c.& turi f. (1971) university of rome carbon 14 dates xii, radiocarbon, 1166 (3), 358-367. aprile f. & ortolani f. (1978) – nuovi dati sulla struttura profonda della piana campana – boll. soc. geol. it., 9977, 591-608. aprile f. & toccaceli r.m. (2002) – nuove conoscenze sulla stratigrafia e distribuzione dei depositi ignimbritici quaternari nel sottosuolo della piana del sarno (salerno campania) – italia meridionale. il quaternario, 1155 (2), 169-174. barberi f., innocenti f., liirer l., munno r., pescatore t., santacroce r. (1978) – the campanian ignimbrite: a major prehistoric eruption in the neapolitan area (italy) – bull. volcanol., 4411 (1), 122. barberi f., cassano e., la torre p., sbrana a. (1991) structural evolution of campi flegrei caldera in the light of volcanological and geophysical data. j.volcanol geotherm res. 4488, 33-49. brancaccio l., cinque a., romano p., rosskopf c., russo f., santangelo n. & santo a. (1991) – geomorphology and neotectonic evolution of a sector of the thyrrenian flank of the southern apennines (region of naples, italy) – z. geom., 8822, suppl. bd., 47-58. brancaccio l., cinque a., romano p., rosskopf c., 286 fig. 13 colonne stratigrafiche relative agli affioramenti più significativi di depositi piroclastici post ignimbrite campana. per le ubicazioni degli affioramenti vedi fig.1. stratigraphical columns for the most significant outcrops of post campanian ignimbrite pyiroclastic deposits. see fig. 1 for location. fig. 14 i depositi piroclastici post ignimbrite campana nella cava abbandonata di san marco evangelista”. a) ic; b) paleosuolo; c) cineriti bianche stratificate e livello pomiceo massivo giallastro; d) suolo attuale. post campanian ignimbrite piroclastic deposits cropping out in the abandoned quarry near san marco evangelista. a) campanian ignimbrite; b) paleosol; c) white layered ash deposits and massive yellowish pumiceous level; d) present day soil. f. bellucci, n. santangelo & a. santo russo f., santangelo n. (1994) l'evoluzione delle pianure costiere della campania: geomorfologia e neotettonica. mem. soc geogr. it., 5533, 313337. cole p.d. & scarpati c. (1993) a facies interpretation of the eruption and emplacement mechanism of the upper part of the neapolitan yellow tuff, campi flegrei, southern italy. bull. volcanol., 5555, 311-326. d’erasmo g., (1931) – studio geologico dei pozzi profondi della campania. boll. soc. natur. in napoli, 4433 , 15-143. de vivo b., rolandi g., gans p. b., calvert a., bohrson w. a., spera f. j. & belkin h. e. (2001) new constraints on the pyroclastic eruptive history of campanian volcanic plain (italy). mineralogy and petrology 7733, 47-65. deino al., southon i., terrasi f., campajola l. and orsi g. (1994) 14 v and 40ar/ 39ar dating of the campanian ignimbrite, phlegrean fields, italy. abstract icog, berkeley, ca, u.s.a. di girolamo p. (1968) petrografia dei tufi campani: il processo di pipernizzazione (tufo-tufo pipernoide-piperno). rend. acc. sc. fis. mat. napoli s. 4, 35, 1-70. di girolamo p., rolandi g., stanzione e d. (1973) l’eruzione di pomici a letto dell’ignimbrite campana. period. min., 4422,, 436-468. di girolamo p. (1978) geotettonic setting of miocene – quaternary volcanism in and around the eastern tyrrhenian sea border (italy) as deduced from major element geochemistry. bull.volcanol. 4411, 421-432 di girolamo p., ghiara m.r., lirer l., munno r., rolandi g., & stanzione d. (1984) vulcanologia e petrografia dei campi flegrei. boll. soc. geol. it., 110033, 349-413. di vito m., sulpizio r., zanchetta g. (1998) i depositi ghiaiosi della valle dei torrenti clanio-acqualonga (campania centro-orientale): significato stratigrafico e paleoambientale. il quat., 1111 (2), 273-286. fisher r., orsi g., ort m., heiken g.(1993) mobility of a large-volume pyroclastic flow -emplacement of the campaninan ignimbrite, italy. j. volcanol. geotherm. res. 5566,, 205-220. iacobacci a., martelli g., perno u. (1959) osservazioni geologiche sul foglio 173 benevento. boll. serv. geol. it., 8800 (1), 73-75. ippolito f., ortolani f., russo m. (1973) struttura marginale tirrenica dell’appennino campano: reinterpretazione di dati di antiche ricerche di idrocarburi. mem. soc. geol. it., 1122, 227-250. munno r. & petrosino p. (in stampa) new constrains on the occurrence of y-3 upper pleistocene tephra marker layer in the tyrrhenian sea. il quaternario. orsi g., civetta l., valentine g.a. (1999) volcanism in the campi flegrei. j. volcanol. geotherm. res. 9911, 470. ort m.h., rosi m., andersonn c.d. (1999) corelation of deposits and vent locations of the proximal campanian ignimbrite deposits, campi flegrei, italy, based on natural remanent magnetization and anisotropy of magnetic susceptibility characteristics. j.volcanol. geotherm. res. 9911,167-178. rolandi g., bellucci f., heizler m. t., belkin h. e. & de vivo b. (2003) tectonic controls on the genesis of ignimbrites from the campanian volcanic zone, southern italy. mineralogy and petrology, ss..ii.., 129. romano p., santo a. & voltaggio m. (1994) l’evoluzione geomorfologica della pianura del f. volturno (campania) durante il tardo quaternario (pleistocene medio-superiore-olocene. il quat., 77 (1), 41-56. rosi m. & sbrana a. (1987) the phlegraean fields. cnr quaderni di la ricerca scientifica, 111144, 175 pp. scandone r., bellucci f., lirer l., rolandi g. (1991) the structure of the campanian plain and the activity of the neapolitan volcanoes (italy). j. volcanol. geothrm. res., 4488, 1-31. wohletz k., orsi g., de vita s. (1995) – eruptive mechanism of the neapolitan yellow tuff interpreted from stratigraphic, chemical and granulometric data. j. vol. geoth. res., 6677, 263-290. 287 ms. ricevuto il 16 giugno 2003 testo definitivo ricevuto il 18 novembre 2003 ms. received: june 16, 2003 final text received: november 18, 2003 segnalazione di nuovi depositi piroclastici ... base unità a limiti inconformi utilizzate per la cartografia dei depositi quaternari nei fogli carg della sicilia nord-occidentale cipriano di maggio, mauro agate, antonio contino, luca basilone & raimondo catalano dipartimento di geologia e geodesia, università degli studi, palermo, e-mail: dimaggio@unipa.it riassunto: di maggio c. et al., unità a limiti inconformi utilizzate per la cartografia dei depositi quaternari nei fogli carg della sicilia nord-occidentale. (it issn 0394-3356, 2009). sono riportati i risultati di uno studio sui depositi quaternari del settore settentrionale siciliano compreso tra trapani e cefalù. dettagliati rilevamenti di campagna e analisi stratigrafiche condotti in questa area nell’ambito del progetto carg hanno consentito di definire diverse unità a limiti inconformi, del rango di sintema e subsintema, che costituiscono la sintesi regionale degli affioramenti quaternari della sicilia nord-occidentale. sono state riconosciute e studiate numerose successioni di terreni di ambiente da continentale a marino costituite da: depositi fluviali, paralici e marini (conglomerati monogenici o poligenici, areniti e/o peliti sciolte o variamente cementate), accumuli eolici (sabbie e arenarie quarzose o carbonatiche, a stratificazione e laminazione incrociata), terreni colluviali (suoli e detriti rimaneggiati con allineamenti di ciottoli), depositi di falda (detriti sciolti o stratificati e cementati), concrezioni calcaree (travertini, croste calcitiche e depositi di grotta) e macereti di frana. i depositi continentali, tipici di ambienti dominati da erosione, affiorano in piccoli e sottili lembi relitti, spesso discontinui e incompleti; i depositi marini e paralici, caratteristici di ambienti a prevalente sedimentazione, si rinvengono in bacini locali e costituiscono affioramenti più estesi e potenti. il rinvenimento di superfici di discontinuità di importanza regionale che limitano inferiormente e superiormente i corpi rocciosi, ha consentito la proposizione di sette distinti sintemi che ricoprono un periodo di tempo che va dal pleistocene inferiore all’olocene. le discontinuità, marcate a volte da paleosuoli, sono rappresentate da superfici di erosione subacquea (piattaforme di abrasione marina e falesie) o subaerea (superfici, ripe, canali, solchi e cavità prodotti da erosione idrica, processi gravitativi o fenomeni carsici), da superfici di non deposizione o, nel caso del limite superiore, dall’attuale superficie topografica. le datazioni e le correlazioni di depositi e limiti inconformi sono state rese possibile da alcuni elementi vincolanti quali: a) presenza di forme fossili significative; b) datazioni isotopiche di depositi desunte dalla letteratura geologica; c) continuità fisica di alcune superfici di discontinuità; d) significato paleoambientale o paleoclimatico di depositi e superfici di discontinuità; e) rapporti geometrici fra superfici di discontinuità e/o corpi rocciosi. abstract: di maggio c. et al., unconformity-bounded stratigraphic units of quaternary deposits mapped for the carg project in northern and western sicily. (it issn 0394-3356, 2009). quaternary deposits of nw sicily mapped for the carg project (geological survey of italy) during detailed geologic and geomorphologic surveys are made up of: a) fluvial, coastal or marine deposits (mono or polygenic conglomerates, arenites or lutites variously cemented, with plane, inclined or cross-bedded stratification/lamination); b) aeolian deposits (quartzous or carbonate sands/sandstones, with cross-bedded stratification/lamination); c) colluvial terrains (reworked soils and breccias variously cemented, in some case laminated, with stone lines); d) scree slopes (breccias or stratified slope deposits – éboulis ordonné); e) carbonate speleothems (travertines, calcretes and cave deposits); e) landslide debris. lower and upper boundaries of the quaternary rocks consist of unconformity surfaces (marked by palaeosols at places), such as: wave cut platforms and cliffs; gullies and rills; erosion surfaces due to sheet erosion or sheet flood; stream channels, fluvial erosion scarps and fluvial erosion/depositional surfaces; separation or depletion surfaces due to mass movement; non depositional surfaces; topographic surfaces. the detection of some unconformity surfaces of regional extent allowed us to define seven main synthems; they have been mapped in several geologic 1:50.000 sheet maps. the marsala synthem is a lower pleistocene 2-80 m thick body of marine/ coastal conglomerates, arenites and lutites, with abundant corals, algae, bryozoa, mollusca (arctica islandica,chlamys septemradiata), benthic foraminifera and planktonic foraminifera (hyalinea baltica, globorotalia truncatulinoides excelsa); its lower boundary is a marine abrasion surface cut into pre-quaternary rocks. the piana di partinico synthem is made up of 1-5 m thick marine/coastal conglomerates and arenites located on a number of marine terrace surfaces related to sea high stand phases of middle pleistocene (oxygen isotope stages – oiss 17-7); these rocks appear correlatable with 1-3 m thick continental deposits (colluvial terrains and travertines) rich in fossil vertebrates belonging to the early middle pleistocene elephas falconeri sicilian faunal complex; its lower boundary is a wave cut platform carved into marsala synthem or prequaternary rocks. the polisano synthem is 1-10 m thick aeolian sandstones and sands with intercalations of breccias talus; the body deposited in coastal, perched or barrier dune, contains rare terrestrial gastropods shells, late middle pleistocene in age (ois 6); its lower boundary is a non-depositional surface at the top of the piana di partinico synthem or older rocks. the barcarello synthem encompasses 1-2 m thick marine/coastal conglomerates and arenites with a rich warm-temperate “senegalese fauna” including strombus bubonius; they belong to two orders of marine terrace (oiss 5e and 5c or 5a) and laterally pass into 1-5 m thick, welded colluvial deposits; the latter are composed of both lutitic terrains (reworked soil) and breccias with angular rock fragments (reworked scree and sediment) in a abundant silt or fine-grained clay matrix (reworked soil) containing terrestrial mollusc shells and fossil vertebrates of the upper pleistocene elephas mnaidriensis sicilian faunal complex; their age is correlated with the ois 5; the lower boundary of synthem is a marine abrasion surface laterally extending to a continental erosion surface; the latter is cutting the polisano synthem or older rocks. the imera settentrionale synthem is made up of middle – upper pleistocene 1-3 m thick fluvial deposits located on river terrace surfaces lying between about 5 and 100 meters above the valley bottom; its lower boundary is a stream erosion surface. the raffo rosso synthem is composed of 1-2 m thick coastal dune aeolian sandstones and sands, 1-7 m thick colluvial or gravitational deposits with fossil mammals of the late upper pleistocene pianetti and castello sicilian faunal complex, 2-10 m thick stratified slope deposits of the last glacial climatic event (oiss 4-2); the lower boundary is a non-depositional surfaces at the top of the barcarello/imera settentrionale synthems or older rocks. the capo plaia synthem is made up of coastal to continental deposits of the last glacial climatic event end – holocene age (oiss 2-1); its lower boundary is formed by variously originated erosion or non-depositional surfaces; the upper boundary is the present day topographic surface. significant environmental changes during the quaternary, directly or indirectly due to tectonic movements (block faulting or uplifting) and/or climatic fluctuations in their turn triggering erosion / depositional processes, appear to originate both unconformity surfaces of regional extent and deposits. parole chiave: stratigrafia, sintema, quaternario, sicilia nord-occidentale, italia. keywords: stratigraphy, synthem, quaternary, nw sicily, italy. il quaternario italian journal of quaternary sciences 22(2), 2009 345-364 346 c. di maggio et al. 1. introduzione i depositi quaternari della sicilia nord-occidentale sono stati oggetto di numerosi studi. gignoux (1913; 1926) per primo segnala depositi marini e di spiaggia del pleistocene inferiore e superiore. fabiani (1941), tongiorgi & trevisan (1953), ottman & picard (1954), bonifay & mars (1959), buccheri (1966) e ruggieri et al. (1968) concentrano le loro attenzioni sui terreni tirreniani affioranti in diverse località delle coste della sicilia occidentale. sulla base del contenuto paleontologico, ruggieri (1967; 1971; 1973), ruggieri & sprovieri (1975; 1983), ruggieri et al. (1975a), ruggieri et al. (1975b) e ruggieri et al. (1984) forniscono schemi stratigrafici dei depositi pleistocenici marini della sicilia nord-occidentale, corredati da una proposta di suddivisione del pleistocene inferiore nei piani santerniano, emiliano e siciliano. la comprensione delle relazioni esistenti fra terrazzi marini e depositi marino-continentali mediante l’ausilio di analisi paleontologiche e termoluminescenza o di studi integrati a carattere geomorfologico, paleontologico e geologico-strutturale, consente a mauz et al. (1997) e di maggio et al. (1999) di ricostruire l’evoluzione stratigrafica e morfotettonica di alcune aree della sicilia nord-occidentale, dal pleistocene medio all’attuale. numerosi sono gli studi paleontologici sui depositi continentali a vertebrati (scinà, 1831; de gregorio, 1925; vaufrey, 1929; brugal, 1987; burgio et al., 1989; burgio & fiore, 1997), in cui il riconoscimento di specie continentali contribuisce alla definizione di schemi biocronologici basati su dati stratigrafici, aminostratigrafici e geomorfologici (belluomini & bada, 1985; burgio & cani, 1988; bada et al., 1991; bonfiglio & burgio, 1992; di maggio et al., 1999; bonfiglio et al., 2003). gli studi stratigrafici sui depositi continentali sono esigui e limitati a poche e semplici segnalazioni di alcuni corpi sedimentari (gi g n o u x, 1913; to n g i o r g i & trevisan, 1953; ottmann & picard, 1954; ruggieri & milone, 1974). locali o parziali ricostruzioni di successioni di terreni continentali e dei rapporti esistenti fra queste successioni e depositi marini e di spiaggia sono prodotte da hugonie (1979; 1982), di maggio (1997), agnesi et al., (1998), cottignoli et al. (2002), bonfiglio et al. (2004) e contino (2005; 2007). tecniche e metodi per studiare la stratigrafia dei terreni continentali e le loro relazioni con i depositi paralici e marini, finalizzate alla ricostruzione delle geometrie dei corpi rocciosi e delle successioni sedimentarie, sono offerte dal progetto nazionale di cartografia geologica alla scala 1:50.000 (progetto carg). nell’ambito di questo progetto, particolare attenzione è rivolta al rilevamento dei depositi continentali plio-quaternari, per i quali è espressamente raccomandato l’utilizzo di unità stratigrafiche a limiti inconformi (“unconformity-bounded stratigraphic units”, ubsu); il loro impiego ha trovato campo d’applicazione anche nel caso di depositi marini debolmente deformati. si tratta di unità stratigrafiche formali costituite da corpi rocciosi delimitati al letto e al tetto da ben definite e identificabili superfici di discontinuità. corpi rocciosi e discontinuità devono possedere importanza regionale affiorando, anche se in maniera discontinua o frammentaria, in aree alquanto estese. la loro unità base è il sintema (chang, 1975) che può comprendere due o più subsintemi e/o unità litostratigrafiche; a loro volta due o più sintemi possono costituire un supersintema (issc, 1994). per ciò che concerne il rilevamento dei fogli geologici della sicilia nord-occidentale interessati dal progetto carg, recenti e dettagliati studi hanno consentito di definire, attraverso il riconoscimento di superfici di discontinuità di importanza regionale, sette ubsu del rango di sintema, che ricoprono un intervallo di tempo compreso fra il pleistocene inferiore e l’olocene; esse rappresentano una sintesi complessiva delle successioni di depositi quaternari. 2. l’area studiata l’area studiata ricopre l’intero settore settentrionale della sicilia centro occidentale, dai monti di trapani alle madonie (figg. 1, 2). nelle regioni centrali e orientali del settore in esame sono presenti tre grandi e compatti gruppi montuosi carbonatici (da est verso ovest madonie, monti di termini imerese e monti di palermo), separati fra loro da grandi vallate a sviluppo n-s, incise in depositi argillosi, attraversate dai fiumi imera settentrionale e torto (tra le madonie e i monti di termini imerese) e dal fiume eleuterio (al limite fra i monti di termini imerese e i monti di palermo); le regioni occidentali e centro-meridionali sono caratterizzate da rilievi carbonatici isolati (monte bonifato, monte inici, dorsale n-s della penisola di capo san vito, monte erice e montagna grande nelle aree occidentali; dorsali e-o di monte kumeta e rocca busambra lungo le propaggini meridionali dell’area indagata), cui si frappongono aree collinari argillose o, lungo la fascia costiera, grandi aree pianeggianti. queste ultime si rinvengono, in modo discontinuo, anche lungo la fascia costiera dei settori centrali ed orientali. nel mediterraneo centro-occidentale, la sicilia costituisce un segmento di catena che si sviluppa lungo il limite tra la placca africana e quella europea, collega le maghrebidi africane con la calabria e gli appennini e si estende dalla sardegna fino alla piattaforma pelagiana (canale di sicilia; fig. 1). dopo la fase orogenica alpina paleogenica, i movimenti compressivi più importanti di questo settore del mediterraneo sono dovuti alla subduzione della crosta adriatico-ionica. in questo quadro la collisione del blocco sardo-corso con il margine continentale africano (bellon et al., 1977; channellet al., 1979; dercourt et al., 1986) è considerata comunemente come la causa primaria per la gran parte della deformazione compressiva nella catena sudappenninica-siciliana (catalano & d’argenio, 1978; catalano et al, 1996 con bibliografia). dal miocene superiore, con la fine della rotazione del blocco sardo-corso, parte dell’orogene alpinoappenninico venne interessato da processi distensivi, associati con il progressivo arretramento del piano di subduzione, immergente verso no, della placca adriatico-ionica al di sotto della calabria, responsabili della formazione ed evoluzione del bacino tirrenico meridionale (malinverno & ryan, 1986; rehault et al, 1987; faccenna et al., 1996; gueguen et al., 1998). il complesso collisionale della sicilia e del suo prolungamento offshore (catalano et al., 1996) è caratterizzato da tre elementi tettonici principali: a) un’area di avampaese, affiorante nella sicilia sudorientale e presente nel canale di sicilia a sud di sciacca. la successione sedimentaria autoctona 347unità a limiti inconformi utilizzate per la cartografia dei depositi ... ricopre un basamento cristallino africano ed è costituita da circa 7 km di carbonati di piattaforma e di scarpata-bacino del triassico-liassico, di carbonati pelagici del giurassico-eocene e di depositi clastici di piattaforma aperta del terziario (patacca et al., fig. 1 carta strutturale della sicilia (modificata da catalano & d’argenio, 1982; catalano et al., 1996): 1. unità dell’avampaese ibleo; 2. unità di piattaforma carbonatico-pelagica (trapanese-saccense); 3. unità di monte genuardo (transizione piattaforma-bacino); 4. unità di mare profondo (sicano); 5. unità di piattaforma carbonatica (panormide); 6. unità di scarpata-bacino (imerese-prepanormide); 7. unità dei flysch miocenici (numidico e flysch interni); 8. unità sicilidi; 9. unità cristalline calabro-peloritane; 10. depositi sinorogeni mio-pliocenici; 11) depositi sintettonici plio-pleistocenici;12. vulcaniti plio-quaternarie; 13. depositi pleistocenici; 14. quadro di unione dei fogli geologici carg in scala 1:50.000. la carta raffigurata in b) illustra i differenti settori crostali della regione centrale del mediterraneo (modificata da catalano et al., 2002): 1. crosta oceanica del mar tirreno; 2. crosta oceanica del bacino algerino; 3. crosta continentale assottigliata kabilo e sarda; 4. crosta continentale (5. assottigliata) africana; 6. crosta oceanica del mar ionio; 7. unità tettoniche sarde; 8. unità kabilo-calabridi; 9. unità siciliane-maghrebidi; 10. prisma di accrezione ionico; 11. fronti di sovrascorrimento; 12. faglia con probabile componente transtensiva; 13. isobate (in km) della moho; 14. limite ipotetico della crosta oceanica ionica o limite margine passivo-oceano ionico; 15. batimetria. geological map of sicily (after catalano & d’argenio, 1982; catalano et al., 1996): 1. hyblean foreland units 2. trapanese-saccense pelagic-carbonate platform units; 3. monte genuardo unit (platform-basin transition); 4. sicanian basinal units; 5. panormide carbonate platform units; 6. imerese-prepanormide slope-to-basin units; 7. numidian and internal flysch units; 8. sicilidi units; 9. calabropeloritani crystalline units; 10. miocene-pliocene synorogenic deposits; 11. plio-pleistocene syntectonic deposits;12. plio-quaternary volcanism; 13. pleistocene deposits; 14. location map of the 1:50.000 geological map sheets (carg project). b) simplified structural map of the central mediterranean area showing the different crustal sectors of the region (after catalano et al., 2002): 1. tyrrhenian oceanic crust; 2. oceanic crust of the algerian basin; 3. kabylian and sardinian thinned continental crust; 4. african continental crust (5. thinned); 6. ionian oceanic crust; 7. sardinian tectonic units; 8. kabilo-calabridi units; 9. siculo-maghrebian units; 10. ionian accretionary wedge; 11. thrust fronts; 12. probably strike-slip (transtensional) fault; 13. isobath (in km) of the moho; 14. ionian oceanic crust hypothetical boundary or passive margin-ionian ocean boundary; 15. bathymetry. 348 1979; catalano & d’argenio, 1982; bianchi et al., 1989; antonelli et al., 1991); b) un’avanfossa recente, localizzata nell’offshore meridionale della sicilia (bacino di gela) e nella regione iblea lungo il margine settentrionale dell’avampaese dove è in parte sepolta dal fronte della catena (falda di gela); c) una catena complessa, vergente verso sse, spessa a luoghi più di 15 km, costituita (dall’interno verso l’esterno) da un elemento “europeo” (unità peloritane), un elemento “tetideo” (unità sicilidi) ed un elemento “africano” (unità appenninicomaghrebidi). le unità più interne disposte nell’offshore settentrionale dell’isola sono generalmente collassate verso nord in relazione all’apertura del tirreno centro-meridionale (rehault et al., 1987). recenti lavori, supportati da numerosi profili sismici a riflessione (catalano et al., 2000; bello et al., 2000), descrivono la catena siciliana come il risultato della sovrapposizione, da occidente ad oriente, di unità tettoniche pellicolari (risultanti dalla deformazione di terreni meso-cenozoici appartenenti agli originari domini bacinali sicilide, imerese e sicano) su un cuneo di thrust, spesso 6-7 km (derivante dalla deformazione di terreni meso-cenozoici appartenenti ad un originario dominio di piattaforma carbonatica trapanese, saccense o panormide). l’insieme così strutturato poggia, a sua volta, sull’avampaese non deformato che affiora nel plateau ibleo e si continua nel canale di sicilia (ibleopelagiano). nell’area in studio (fig. 1) le strutture più antiche sono oggi di difficile riconoscimento poiché ad esse spesso si sono sovrapposti gli effetti della successiva tettonica trascorrente e trastensiva correlabile all’apertura del tirreno (plio-pleistocene). i corpi piegati e sovrascorsi, di cui spesso si riconoscono solo i relitti delle strutture originarie, sono oggi dislocati e ribassati, generalmente verso il settore costiero settentrionale. vengono riconosciuti due sistemi di faglie con andamento no-se e ne-so. quest’ultimo appare il più importante anche in ragione dei rigetti riconoscibili che raggiungono il migliaio di metri. nel pliocene inferiore le aree più settentrionali hanno subito una subsidenza differenziale che è stata attiva fino a 2.4 milioni di anni fa, con settori che si approfondivano rapidamente. durante questo intervallo il substrato deformato venne scomposto lungo faglie listriche dirette con crescita che hanno determinato l’apertura di half-graben progressivamente riempiti da sedimenti clastici. negli ultimi 500.000 anni l’area risulta tettonicamente ancora attiva, con faglie dirette e trascorrenti che dislocano anche i depositi del tirreniano, o di età più recente (abate et al., 1998), affioranti a quote differenti lungo la fascia costiera. questi movimenti accompagnano un lento ma prolungato sollevamento che interessa la piattaforma continentale, la costa e anche le aree più interne, lungo tutta la sicilia nord-occidentale (mauz et al., 1997; di maggio et al., 1999). i meccanismi focali compressivi e/o transpressivi ricavati dagli eventi tellurici di bassa intensità e profondità, recentemente verificatisi nell’offshore di capo san vito (agate et al., 2000), suggeriscono come l’attività tettonica nell’area sia attualmente segnata dal succedersi di eventi compressivi e/o traspressivi. i caratteri geomorfologici e morfotettonici di vaste aree della sicilia nord-occidentale sono stati descritti da hugonie (1979; 1982), di maggio (1997; 2000), agnesi et al. (2000a), agnesi et al. (2002) e bonfiglio et al. (2004). dati inediti recenti, cui si aggiungono ricerche specifiche condotte nell’ambito del progetto carg, integrano le informazioni contenute in letteratura. l’assetto geomorfologico della sicilia nord occidentale è contrassegnato da una sostanziale congruenza tra tettonica e morfologia, con una significativa coincidenza fra alti e bassi strutturali e topografici. questa coincidenza è da imputare in alcuni casi a processi tettonici, in altri all’erosione selettiva. infatti: a) nei settori costieri occidentali e settentrionali si rinvengono grandi forme tettoniche (horst, graben e halfgraben) dovute a eventi distensivi ripetutisi nel corso del quaternario, con imponenti scarpate di faglia rielaborate dal mare (falesie di faglia o paleofalesie di faglia degradate); b) nelle aree immediatamente più interne si trovano forme strutturali derivate (brachianticlinali o rilievi di anticlinale e brachisinclinali o valli di sinclinale), delimitate da estese scarpate e versanti di linea di faglia. in questo secondo caso e malgrado l’erosione selettiva, la congruenza fra struttura e morfologia si è realizzata grazie alla sovrapposizione di rocce tenere (coperture terrigene cenozoiche) su rocce dure (carbonati mesozoici). questo assetto ha favorito: 1) lo smantellamento delle coperture più erodibili e la conseguente esumazione del più resistente substrato carbonatico nelle situazioni di alto strutturale, dove il rallentamento dell’erosione ha determinato situazioni di alto topografico (principali rilievi montuosi); 2) il continuo e progressivo approfondimento delle originarie aree di basso strutturale, nelle quali gli spessori delle coperture erano maggiori, con la conseguente formazione di accentuati bassi topografici (principali depressioni vallive). rare sono le situazioni di inversione del rilievo, localizzate nelle aree in cui si è avuta la venuta a giorno di rocce tenere al di sotto di rocce dure. molto diffuse le forme relitte dovute, o conseguenti, a: erosione laterale/spianamento (differenti cicli, ripetuti dalle aree sommitali verso le quote più basse, di superfici di spianamento, glacis di erosione in rocce tenere, piattaforme di abrasione marina e superfici di erosione fluviale); processi di approfondimento (gole fluviali, valli a “v”, valli sospese ed abbandonate); aumento delle energie del rilievo (diverse forme prodotte da erosione selettiva o da deformazioni gravitative profonde di versante). le modificazioni geomorfologiche del rilievo sono indotte da una tendenza all’abbassamento del livello di base dell’erosione (agnesi et al., 2000a; di maggio, 2000; agnesi et al., 2002). questa tendenza sembra essere d e t e r m i n a t a d a l l a f a s e d i u p l i f t r e g i o n a l e d e l quaternario. alla fase di sollevamento si sono sovrimposte oscillazioni ad alta frequenza (1-2.10 2 ky) indotte dalle fluttuazioni glacioeustatiche (catalano et al., 1998), con l’alternarsi di stazionamenti del livello di base ad alte (durante eventi climatici caldi) e a basse quote (durante eventi climatici freddi). la fase di uplift, unitamente alla riduzione areale del settore settentrionale della catena emersa prodotta dalla tettonica distensiva, è quindi responsabile del ripetersi dei processi morfogenetici verso quote via via più basse. c. di maggio et al. 349 3. metodi e tecniche analitiche i depositi quaternari sono stati cartografati alla scala di 1:10.000, con particolare cura anche per gli affioramenti di modesta estensione, separando i differenti litotipi affioranti (fig. 2). sono state ricostruite numerose (più di un centinaio) e dettagliate colonne stratigrafiche che hanno mostrato i rapporti geometrici esistenti fra i litotipi. osservazioni paleontologiche, granulometriche, tessiturali e composizionali dei depositi, hanno consentito il riconoscimento delle strutture sedimentarie principali e le associazioni fossilifere più indicative. studi geomorfologici, condotti tramite indagini dirette e osservazioni fotogeologiche, hanno contribuito sia al riconoscimento delle facies sedimentarie dei depositi (attraverso l’individuazione di forme di accumulo e dei relativi sedimenti), sia all’interpretazione del contesto geomorfologico e morfotettonico in cui le successioni di terreni si sono conservate. di conseguenza le ricerche hanno privilegiato: aree interessate da “rapida” sedimentazione marina o costiera (graben e halfgraben presenti lungo le fasce costiere, sommersi durante il pleistocene inferiore e, a partire dal pleistocene medio, gradualmente emersi); superfici di terrazzi marini o fluviali; zone al piede di scarpate o di versanti rocciosi fortemente acclivi; versanti argillosi a media o bassa inclinazione; aree di fondovalle; spiagge e aree costiere; depressioni o cavità carsiche; grotte carsiche o marine. particolare cura è stata rivolta allo studio delle superfici di discontinuità. la loro interpretazione è stata possibile grazie ad analisi stratigrafiche (riconoscimento di discordanze angolari, paraconcordanze, lacune), stratigrafico-geomorfologiche (riconoscimento di superfici di erosione/deposizione attraverso la ricostruzione dei processi morfogenetici responsabili della loro genesi) e pedogenetiche (riconoscimento di paleosuoli). per la ricostruzione delle successioni di terreni e la datazione e correlazione di depositi e/o superfici (fig, 3) sono stati utilizzati: 1) metodi geometrici basati sui principi di sovrapposizione (depositi più recenti ricoprono superfici e depositi più antichi), intersezione (superfici di discontinuità tagliano depositi e/o superfici più antichi e risultano sigillate o tagliate, rispettivamente, da depositi o superfici più recenti) e di continuità (prosecuzione fisica, più o meno ininterrotta, di affioramenti e, soprattutto, di superfici di discontinuità), che hanno consentito la ricostruzione di elementi ante e post quem; 2) contenuto fossilifero, che ha permesso il riconoscimento di depositi e superfici “guida” (vincoli cronologici); 3) datazioni di depositi condotte in passato da altri autori con metodi di termoluminescenza (mauz et al., 1997) o di aminostratigrafia (hearty et al., 1986; bada et al., 1991), le cui informazioni sono state ricavate da consultazione bibliografica; 4) affinità fra depositi anche molto distanti, ma con analoghe caratteristiche e uguali relazioni geometriche con altri corpi rocciosi e/o superfici; 5) analisi altimetriche basate sulle quote assolute (per superfici di terrazzi marini e relativi depositi) o sulle differenze di quota rispetto ai fondovalle (per superfici di terrazzi fluviali e relativi depositi), tenendo naturalmente conto delle possibili deformazioni tettoniche; 6) analisi paleoclimatiche e paleoambientali, che hanno vincolato la collocazione di alcuni corpi rocciosi a ben definiti eventi climatici, caldi o freddi, del quaternario. 4. litofacies dei depositi quaternari nell’area studiata sono stati riconosciuti numerosi corpi rocciosi quaternari (fig. 2) caratterizzati da specifiche facies. depositi marini: arenarie calcaree o quarzose a stratificazione piano-parallela, con livelli ruditici, contenenti coralli, briozoi, alghe e molluschi (fra questi ultimi alcuni ospiti nordici), passanti localmente a biolititi a fig. 2 carta dei sintemi quaternari della sicilia nord-occidentale: 1. sintema di capo plaia; 2. sintema di raffo rosso; 3. sintema di barcarello; 4. sintema di polisano; 5 sintema della piana di partinico; 6. sintema dell’imera settentrionale; 7. sintema di marsala; 8. principali scarpate/versanti di faglia e falesie/paleofalesie di faglia. quaternary synthem map of nw sicily: 1. capo plaia synthem; 2. raffo rosso synthem; 3. barcarello synthem; 4. polisano synthem; 5 piana di partinico synthem; 6. imera settentrionale synthem; 7. marsala synthem; 8. main fault scarps or slopes and fault cliffs or abandoned cliffs. unità a limiti inconformi utilizzate per la cartografia dei depositi ... 350 coralli, di ambiente di piattaforma o di scogliera; argille a foraminiferi planctonici e con molluschi ospiti nordici, di ambiente neritico-batiale. questi depositi si rinvengono lungo le aree costiere pianeggianti impostate su depressioni tettoniche. depositi di transizione: ghiaie attuali o conglomerati relitti, talvolta bioclastici, generalmente poligenici ed eterometrici, a ciottoli prevalentemente appiattiti, con contenuto fossilifero prevalentemente costituito da ospiti senegalesi, di ambiente intertidale; arenarie calcaree o quarzose a stratificazione e laminazione piano-parallela, inclinata o incrociata, con livelli bioturbati, a luoghi ricche di gusci di molluschi, di ambiente di spiaggia sommersa; sabbie attuali o arenarie relitte a stratificazione o laminazione pianoparallela, di ambiente di spiaggia intertidale ed emersa; arenarie e conglomerati a stratificazione e laminazione piano-parallela o inclinata, di ambiente di delta sommerso; sabbie attuali e arenarie calcaree o quarzose, a stratificazione e laminazione incrociata, in facies di duna di retrospiaggia; blocchi decimetrici (diametro massimo 1 m), da sciolti (attuali) a cementati, organizzati in cordoni paralleli alle attuali o antiche linee di costa, in posizione comunque arretrata e a pochi metri di distanza dalle ripe marine, prodotti dalle mareggiate più intense (depositi di tempesta). i depositi di transizione si ritrovano su antiche superfici di abrasione marina, all’interno di grotte marine, lungo fasce costiere attuali o relitte o alternati ai precedenti depositi marini, testimoniando così antiche oscillazioni del livello marino. depositi fluviali: ghiaie e conglomerati poligenici a ciottoli prevalentemente arrotondati, talvolta con strutture embricate; sabbie e arenarie generalmente monogeniche, con livelli a laminazione incrociata o pianoparallela; rari e sottili livelli pelitici con blanda stratificazione piano-parallela. questi depositi sono solitamente organizzati in livelli ben classati a struttura lenticolare. sono presenti nei principali fondovalle, costituendo le attuali pianure e conoidi alluvionali, e sospesi lungo i versanti vallivi, ove ricoprono superfici di erosione fluviale abbandonate. depositi eolici: sabbie e arenarie di natura quarzosa o carbonatica, a stratificazione e laminazione incrociata, contenenti raramente gusci di polmonati. al loro interno, ma solo nel caso di depositi di duna di ostacolo, si alternano a livelli ruditici a ciottoletti, ciottoli e più rari blocchi rocciosi spigolosi (accumuli di crollo o detriti di falda) derivanti dalla degradazione dei sovrastanti versanti. si rinvengono al piede dei principali versanti montuosi che si affacciano lungo le aree costiere pianeggianti della sicilia nord-occidentale, costituendo così delle dune di ostacolo, o lungo le stesse aree pianeggianti, con caratteri di duna costiera. i depositi di duna di ostacolo, essendo generalmente sepolti da detriti e colluvi più recenti, sono stati spesso riconosciuti grazie a tagli artificiali; i depositi di duna costiera sono più facilmente riconoscibili in quanto preservano l’originaria forma. depositi colluviali: suoli pelitici o sabbiosi rimaneggiati, variamente cementati, contenenti, a luoghi, gusci di gasteropodi terrestri o resti di vertebrati; livelli detritici a clasti da arenitici a ruditici (essenzialmente ciottoli), questi ultimi da angolosi a sub-arrotondati e per lo più fangosostenuti in matrice terrosa o sabbiosa; allineamenti di ciottoli alterati immersi in matrice pelitica (“stone line”, sensu ruhe, 1959; retallack, 1990). affiorano diffusamente in tutta l’area studiata. gli accumuli più consistenti si trovano lungo i versanti in argilla, al piede delle scarpate o dei pendii rocciosi fortemente acclivi (intercalati a depositi di falda detritica) e all’interno di depressioni, cavità e grotte carsiche o marine. generalmente si originano lungo superfici inclinate, dove si hanno materiali sciolti (depositi) o rocce tenere (argille alterate e suoli) che possono facilmente essere presi in carico dalle acque dilavanti, sebbene il loro trasporto e la loro successiva sedimentazione possa per qualche chilometro inoltrarsi, nel caso di inondazioni a coltre o di trasporto in massa, fino alle confinanti zone pianeggianti. fig. 3 rapporti geometrici fra depositi quaternari e/o superfici di discontinuità lungo il versante occidentale di montagna raffo rosso. el suoli attuali. sintema di capo plaia: cpc accumuli di crollo; cpcl detriti di falda e depositi colluviali. sintema di raffo rosso: rrdp detriti stratificati e cementati con intercalazioni di paleosuoli; rrdr detriti stratificati e cementati fortemente rimaneggiati; rrds detriti stratificati e cementati; rrc accumuli di crollo. sintema di barcarello: bc depositi colluviali cementati. sintema di polisano: psc accumuli di crollo; pse depositi eolici. sintema della piana di partinico: pp depositi costieri. sb substrato mesozoico. geometric relationships between quaternary deposits and/or unconformity surfaces along the western slope of montagna raffo rosso. el recent soils. capo plaia synthem: cpc fall accumulations; cpcl breccias talus and colluvial deposits. raffo rosso synthem: rrdp stratified slope deposits with palaeosols; rrdr reworked stratified slope deposits; rrds stratified slope deposits; rrc fall accumulations. barcarello synthem: bc welded colluvial deposits. polisano synthem: psc fall accumulations; pse aeolian deposits. piana di partinico synthem: pp coastal deposits. sb mesozoic substrate. c. di maggio et al. depositi di falda: frammenti rocciosi spigolosi o angolosi, di differente granulometria, sciolti o debolmente cementati, derivanti dalla degradazione dei versanti e accumulatisi alla base dei pendii per processi di caduta di detrito e, occasionalmente, di crollo. seppelliti da materiali più recenti e affioranti solo lungo tagli naturali o artificiali, si hanno anche spessi pacchi di detriti stratificati e cementati (éboulis ordonné), organizzati in livelli solitamente ben classati, tipici di un clima più freddo ed arido dell’attuale. si alloggiano al piede delle scarpate e dei versanti rocciosi subverticali, laddove le condizioni topografiche o l’assenza di agenti erosivi ha consentito la formazione di una falda detritica. depositi di frana: materiali variegati per dimensione e composizione, a giacitura caotica (accumuli di crollo/ribaltamento, colamento e scorrimento traslativo di blocchi) o in qualche modo “ordinata” (accumuli di scorrimento rotazionale o di scorrimento traslativo di roccia in blocco). si raccolgono al piede di scarpate e pendii molto acclivi (macereti di crollo/ribaltamento o, in minor misura, di scorrimento traslativo) o lungo i versanti a componente argillosa (accumuli di scorrimento o di colamento). depositi chimici: locali concrezionamenti, croste calcitiche e depositi di grotta in genere, o di ben più estesi e potenti corpi di travertino. si trovano all’interno di cavità e grotte carsiche o marine e in corrispondenza di attuali o antichi punti di risorgenza, cascata o di turbolenza fluviale. 5. unità stratigrafiche a limiti inconformi i depositi appena descritti si rinvengono isolati e in lembi relitti, oppure costituiscono affioramenti più estesi con spessori significativi di differenti litotipi, con variazioni laterali e verticali di facies. i corpi sedimentari sono limitati da superfici di discontinuità e, per i depositi più recenti, il limite superiore è la superficie topografica attuale. le discontinuità in esame, marcate a volte dalla presenza di paleosuoli, corrispondono tanto a superfici di non deposizione, quanto a superfici di erosione subacquea o subarea. le superfici di erosione individuate costituiscono il risultato di processi di tipo via via marino-costiero, idrico (dovuti alle acque correnti superficiali, incanalate o diffuse), gravitativo o carsico. assumono l’aspetto di: piattaforme di abrasione marina; falesie o ripe di erosione costiera, con relativi solchi e grotte marine; superfici di erosione fluviale; scarpate o ripe fluviali; alvei fluviali; rivoli e solchi di ruscellamento; superfici dilavate prodotte da erosione areale o inondazione a coltre; superfici di distacco di frana; canali di frana o di trasporto in massa; piani di soluzione chimica (superfici di cavità o di depressioni carsiche in genere). alcune di queste superfici sono geneticamente legate a cambiamenti ambientali a vasta scala collegati a variazioni climatiche o ad eventi tettonici, con bruschi passaggi da fasi di sedimentazione (o di erosione) a fasi di erosione (o di sedimentazione): in questo caso esse assumono una importanza regionale. altre sono invece riconducibili a modificazioni ambientali locali, rivestendo un certo interesse solo per aree di limitata estensione. a luoghi la discontinuità-limite fra due o più corpi rocciosi può anche essere verticale e, nel caso di accumuli isolati e discontinui, i depositi più recenti possono ritrovarsi a quote inferiori rispetto a depositi più antichi. l’analisi sedimentaria dei depositi studiati, la geometria dei rapporti fra di loro esistenti e la giacitura delle discontinuità a scala regionale ha consentito di separare vari sintemi, più avanti illustrati. corpi rocciosi e superfici di inconformità sono stati datati e, quando possibile, correlati (fig. 4) con le curve delle variazioni degli stadi isotopici del 18o ‰ (ois, oxygen isotope stage) di shackleton (1995). 5.1 sintema di marsala l’unità sedimentaria consiste di alternanze localmente cicliche di: a) sottili livelli di conglomerati, arenarie e sabbie, con bioclasti (ambiente intertidale o di spiaggia emersa); b) arenarie e conglomerati a stratificazione e laminazione inclinata (fig. 5) o piano-parallela (ambiente di delta sommerso); c) calciruditi e biolititi a coralli (ambiente di scogliera); d) arenarie e sabbie bioclastiche o litoclastiche prevalentemente carbonatiche e in subordine quarzose, a stratificazione e laminazione piano-parallela o incrociata, con livelli bioturbati (ambiente di spiaggia sommersa o infra-circalitorale); e) argille, argille marnose e argille siltoso-sabbiose (ambiente infra-circalitorale). la successione risulta a volte interrotta da locali superfici di abrasione marina ubicate a diverse altezze stratigrafiche. lo spessore varia da 1-2 m fino a più di 90 m. nella piana di palermo questi depositi raggiungono spessori sino a circa 95 m (calvi et al., 2000; contino et al., 2006). i livelli carbonato-clastici sono caratterizzati dalla presenza di coralli, briozoi, spugne, alghe, vermetidi, scafopodi, echinodermi, foraminiferi bentonici, gasteropodi (patella spp.), lamellibranchi (glycimeris spp., pecten jacobaeus, chlamys multistriata, chlamys septemradiata, arctica islandica, ostrea spp.) e molluschi. i depositi argillo-siltoso-marnosi contengono foraminiferi planctonici (globorotalia truncatulinoides excelsa) o bentonici (hyalinea baltica) e ostracodi (di stefano & rio, 1981). diffuso in tutta la sicilia nord-occidentale, affiora in depressioni costiere pianeggianti aperte verso il mare e delimitate verso l’interno da grandi paleofalesie di faglia; queste depressioni coincidono con bassi tettonici. il limite inferiore, laddove è direttamente osservabile sul terreno, è una superficie di abrasione marina intagliata su terreni pre-quaternari e debolmente inclinata verso mare (mediamente 1°-3°), a luoghi interrotta da paleofalesie o scarpate di faglia alte 1-5 m. questa superficie è cartografabile lungo le zone periferiche delle piane, dove affiora tra le quote di 150-200 m (aree più interne) e di 1-2 m s.l.m. (zone costiere marginali). nelle zone costiere centrali il limite inferiore, non direttamente visibile, è stato intercettato, attraverso numerose perforazioni di pozzi, fino ad alcune decine di metri di profondità al di sotto dell’attuale livello marino. l’età dei depositi viene comunemente attribuita al pleistocene inferiore (ruggieri, 1967; 1978; ruggieri et al., 1975b; mauz & renda, 1991) e, precisamente, alle unità informali emiliano p.p. e siciliano (sensu ruggieri et al., 1984) corrispondenti alla parte media e alta del calabriano (nell’accezione di cita et al., 2006; cita et al., 2008); l’età del limite inferiore dovrebbe di conseguenza collocarsi nel calabriano, parte media. 351unità a limiti inconformi utilizzate per la cartografia dei depositi ... la località-tipo proposta è l’area di marsala (estremità occidentale della sicilia) dove si ha una continua ed estesa successione, potente almeno 80 m, di calcareniti litoclastiche e bioclastiche e di argille e argille sabbiose fossilifere, queste ultime presenti nel sottosuolo o intercettate in profondità da alcuni pozzi. depositi colluviali, costituiti da prodotti eluviali e detriti rimaneggiati, contenenti resti di vertebrati appartenenti al complesso faunistico di monte pellegrino (bonfiglio et al., 2002, con bibliografia) del pleistocene inferiore (burgio & fiore, 1997; masini et al., 2008, con bibliografia), sono stati rinvenuti all’interno di cavità carsiche esclusivamente nell’area di monte pellegrino (palermo). essi poggiano su una superficie di dissoluzione carsica che intacca dei calcari mesozoici. considerando la loro età (da 1,6 a 0,9 ma), questi depositi potrebbero appartenere al sintema di marsala, sebbene l’intervallo di tempo ricoperto (santerniano – siciliano, sensu ruggieri et al., 1984), non escluda una loro collocazione più indietro nel tempo rispetto all’età del sintema in oggetto. 5.1.1 considerazioni la deposizione del sintema di marsala è probabilmente da collegare ad un evento tettonico distensivo del pleistocene inferiore che, nelle aree settentrionali della sicilia, avrebbe dato luogo ad una gradinata di faglie, con rigetti di centinaia di metri e il collasso di grandi blocchi al di sotto del livello del mare. in corrispondenza dei blocchi meno ribassati si sarebbero create delle condizioni di mare poco profondo che 352 fig. 4 schema di correlazione cronologico. chronological correlation scheme. fig. 5 piana di castelluzzo. sintema di marsala: calcareniti a laminazione inclinata. piana di castelluzzo. marsala synthem: calcarenites with inclined lamination. c. di maggio et al. avrebbero consentito il modellamento dei fondali ad opera del moto ondoso, con la formazione di piattaforme di abrasione marina progressivamente interessate dalla sedimentazione di depositi costiero-marini. piattaforme di abrasione si sarebbero sviluppate anche ai piedi delle falesie (scarpate di faglia rielaborate dal mare) a causa del loro arretramento parallelo. nei blocchi più dislocati dalla tettonica, con condizioni di mare più profondo e maggiore spazio di accomodamento, si sarebbero rapidamente accumulati notevoli spessori di depositi di piattaforma interna; questi ultimi ricoprirono direttamente una superficie di erosione posta al tetto dei blocchi sprofondati (superficie di erosione subaerea “annegata”?), come è visibile nei profili sismici a riflessione dell’offshore siciliano (agate et al., 1993). il rinvenimento del limite inferiore dislocato a profondità differenti potrebbe comunque essere indicativo di: a) blocchi sprofondati a quote differenti, successivamente colmati dalla sedimentazione marina; b) blocchi dislocati anche successivamente all’inizio della sedimentazione. la prima ipotesi comporta l’esistenza di una fase tettonica più antica dell’inizio della sedimentazione; la seconda ipotesi prevede una prima importante fase tettonica, una fase di sedimentazione e, contemporaneamente o successivamente, una nuova ripresa dell’attività tettonica, con rigetti stavolta dell’ordine di pochi metri (cfr. mauz & renda, 1991). l’alternanza ciclica di depositi paralici e di mare più profondo e la presenza, al loro interno, di superfici di erosione marina di rango inferiore (piattaforme e palofalesie), dovrebbe invece essere collegata alle oscillazioni del livello marino prodotte da fluttuazioni climatiche. i depositi continentali a vertebrati rinvenuti a monte pellegrino intrappolati all’interno di cavità, potrebbero indicare invece la prosecuzione di una lunga fase di continentalità, dominata da processi carsici, pedogenetici e di scorrimento idrico diffuso, relativamente ai settori collinari e montuosi prospicienti le depressioni costiere. 5.2 sintema della piana di partinico i corpi sedimentari del sintema sono costituiti da alternanze di arenarie bioclastiche e biolititi algali (ambiente di piattaforma interna), conglomerati e sabbie con impronte di fondo, depositi di tempesta a laminazione incrociata ed hummocky (ambiente di spiaggia), suoli e brecce rimaneggiati (formati da livelli terrosi e livelli detritici con clasti immersi in abbondante matrice) e concrezioni carbonatiche (ambiente continentale). il contenuto fossilifero è dato da faune marine tipiche di fasi calde del pleistocene (vari ospiti senegalesi) e da associazioni di vertebrati del complesso faunistico siciliano ad elephas falconeri (sensu burgio & cani, 1988; bonfiglio et al., 2002 con bibliografia). i depositi del sintema affiorano nelle depressioni costiere pianeggianti e, in modo discontinuo, lungo l’intera fascia costiera della sicilia nord-occidentale, poggiati su piattaforme di abrasione disposte a varie quote e appartenenti a più ordini di terrazzi marini (fig. 6) o alloggiati all’interno di cavità carsiche o marine. il limite inferiore è una superficie di abrasione marina intagliata su depositi del sintema di marsala o su terreni più antichi e rinvenuta fra circa 150 e 250 m s.l.m. a quota inferiore, da 150-200 m fino a circa 7-26 m s.l.m., tale superficie risulta tagliata da più recenti ripiani di erosione marina (piattaforme di abrasione e paleofalesie) considerati superfici di inconformità di rango inferiore; questi ripiani vanno a costituire una gradinata di terrazzi, prodotta dalle oscillazioni relative del livello marino, su cui si preservano depositi di spiaggia e di piattaforma interna via via più recenti. sulla base del contenuto paleontologico, delle evidenze, stratigrafiche e geomorfologiche e dei risultati ottenuti da datazioni isotopiche, l’età risulta pleistocene medio (mauz et al., 1997; di maggio et al., 1999). località-tipo proposta è l’area tra alcamo e partinico (piana di partinico) dove affiorano limite inferiore e depositi di terrazzo marino disposti a differenti quote e riferibili a più fasi di stazionamento alto del mare nel pleistocene medio. anche nella piana di buonfornello e nei rilievi collinari adiacenti si rinviene una successione ben conservata di depositi essenzialmente costieri, disposti su una gradinata di terrazzi marini, che si sviluppa da 30 fino a circa 250 m s.l.m. sulla base del riconoscimento di una superficie di discontinuità di estensione regionale, correlabile con l’evento climatico caldo immediatamente precedente il tirreniano (ois 7), è stato possibile distinguere due subsintemi. 5.2.1 subsintema di piana di sopra è rappresentato da successioni di depositi continentali, paralici o marini, con geometrie generalmente tabulari, costituite da alternanze di: a) conglomerati poligenici ed eterometrici a supporto granulare, con ciottoli talvolta perforati da spugne clionidi; b) arenarie 353 fig. 6 piana di sopra. sintema della piana di partinico: ppcl suoli e detriti rimaneggiati contenenti resti di vertebrati del complesso faunistico ad elephas falconeri; ppm conglomerati di spiaggia. sm superficie di abrasione marina posta a circa 45 m s.l.m. sb substrato mesozoico. piana di sopra. piana di partinico synthem: ppcl reworked soils and breccias including fossil vertebrates belonging to the elephas falconeri sicilian faunal complex; ppm coastal conglomerates. sm wave-cut surfaces located at about 45 m a.s.l. sb mesozoic substrate. unità a limiti inconformi utilizzate per la cartografia dei depositi ... e sabbie bioclastiche o litoclastiche, a laminazione piano-parallela o, più raramente, incrociata; c) sottili e rari livelli di biolititi algali; d) depositi colluviali variamente cementati, costituiti da suoli terrosi rimaneggiati, con inclusioni di rari clasti da millimetrici a decimetrici, o da livelli detritici di tipo breccia, con frammenti rocciosi talvolta allineati (stone line) immersi in matrice terrosa e/o sabbiosa. i depositi in esame sono localmente deformati da faglie oblique (mauz et al., 1997; di maggio et al., 1999; contino, 2002) il contenuto fossilifero dei depositi marini e di spiaggia è rappresentato da numerosi ospiti senegalesi come spugne, alghe, coralli (cladocora caespitosa), frammenti scheletrici di pesci, lamellibranchi (pettinidi, spondylus spp., glycimeris spp., ostrea spp.), gasteropodi (patella caerulea) e molluschi; quello dei depositi continentali è prevalentemente costituito da gusci di gasteropodi terrestri e da resti di mammiferi appartenenti al complesso faunistico ad elephas falconeri del pleistocene medio (parte inferiore). il limite inferiore del subsintema è costituito dalla piattaforma di abrasione del terrazzo marino più antico conservatosi; questa superficie si rinviene lungo la fascia costiera della sicilia nord-occidentale fra circa 150-250 m s.l.m. nella piana di partinico, in corrispondenza del centro abitato di alcamo a circa 250 m s.l.m., la stessa superficie appare seppellita da un pacco di sabbie e arenarie fossilifere di spiaggia sulle quali poggia un “bancone” di travertino; le datazioni radiometriche delle concrezioni calcaree superiori, ottenute con metodo aminostratigrafico, hanno restituito un’età di circa 455 +/90 ka (bada et al., 1991). all’interno del subsintema sono riconoscibili diverse superfici di inconformità di rango inferiore, costituite da superfici di erosione marina (piattaforme e paleofalesie) appartenenti a più ordini di terrazzi marini, situate a quote inferiori (fino a circa 16-50 m s.l.m.). le alternanze di depositi di spiaggia e continentali descritte sono state riconosciute anche all’interno di numerosi ripari e grotte marini o di solchi di battente, posizionati fra circa 30 e poco più di 100 m s.l.m., a quote correlabili con quelle dei diversi ordini di terrazzi marini in esame. depositi francamente continentali, solitamente detriti o colluvi terrosi di riempimento di grotte, cavità e depressioni di origine carsica, affiorano nelle aree più interne, anche in quelle più lontane dalle zone costiere. banchi di travertino, attribuiti da hugonie (1979) al pleistocene medio, affiorano in vicinanza di zone di risorgenza o lungo aree caratterizzate da flussi idrici laminari. gli spessori di queste successioni continentali sono mediamente di 1-2 m, raramente superano i 5 m; solo nel caso dei depositi di travertino si raggiungono potenze di una decina di metri. considerando le quote relativamente elevate alle quali si rinvengono, i depositi marini o di spiaggia che si trovano sulle superfici di abrasione dei terrazzi marini e all’interno di grotte, ripari e solchi marini, dovrebbero essere correlati a fasi di stazionamento alto del livello del mare. sulla base sia di analisi stratigrafiche, geomorfologiche e paleontologiche condotte da di maggio et al. (1999) nell’area di piana di sopra (penisola di capo san vito, monti di trapani), sia di numerose datazioni effettuate con il metodo della termoluminescenza da mauz et al. (1997) su depositi di terrazzo marino distribuiti fra 18 e 40 m s.l.m. nella piana di partinico, sono state proposte età correlabili agli ois 9, 11 e 1317 (pleistocene medio). sulla base del contenuto faunistico e di datazioni isotopiche (bada et al.,1991; rhodes 1996), i depositi continentali possono invece essere genericamente attribuiti al pleistocene medio (ois che vanno dal 17-19 fino all’8). l’analisi stratigrafica dei dati descritti consente di assegnare all’inizio del pleistocene medio l’età del limite inferiore del subsintema di piana di sopra; quest’ultimo rappresenta anche la superficie basale del sintema di partinico. la località-tipo proposta è l’area di piana di sopra (estremità nord-occidentale della penisola di capo san vito) dove, lungo alcune paleofalesie delimitanti una piattaforma di abrasione marina sommitale, sono intagliati numerosi solchi e grotte contenenti successioni di terreni marini e continentali; cavità e depositi sono distribuiti fra circa 20 e 80 m s.l.m. e sono riferibili a più cicli di stazionamento alto del mare nel pleistocene medio. 5.2.2.subsintema di tommaso natale i corpi sedimentari sono costituiti da: a) conglomerati poligenici di spiaggia; b) brecce cementate, con scheletro granosostenuto costituito da blocchi decimetrici da angolosi a sub-arrotondati, con scarsa matrice ruditica fine e arenitica, a giacitura caotica, prodotti da intense mareggiate (depositi di tempesta); c) calcareniti e sabbie calcaree o, in subordine, quarzose, con livelli bioclastici, a stratificazione piano-parallela e laminazione piano parallela o incrociata. lo spessore medio è di circa 1-2 m. questi depositi appaiono talvolta dislocati da faglie con rigetti verticali di pochi metri e componente di movimento orizzontale (cfr. di maggio et al., 1999; agnesi et al., 2000a; di maggio, 2000). il contenuto fossilifero è costituito da ospiti senegalesi quali brachiopodi (megathiris detruncata), cirripedi, echinodermi (arbacia lixula), coralli (astroides calycularis), lamellibranchi (corbula revoluta, chlamys multistriata, ostrea edulis, pecten jacobaeus), gasteropodi (cymatium ficoides, cantharus viverratus) e molluschi in genere. il limite inferiore è una piattaforma di abrasione marina che può svilupparsi, a seconda dei diversi settori costituenti la fascia costiera della sicilia nord-occidentale, fra 8-26 m s.l.m. (quota minima) e 15-50 m s.l.m. (quota massima); essa è incisa a spese dei depositi del subsintema di piana di sopra (o di terreni più antichi) ed è talvolta contrassegnata da paleosuoli. sulla base del contenuto fossilifero e di datazioni radiometriche effettuate su resti fossili o frammenti quarzosi da hearty et al. (1986) nei pressi dell’abitato di tommaso natale e da mauz et al. (1997) nella piana di partinico, l’età di questi depositi (e della sottostante piattaforma di abrasione marina che costituisce il limite inferiore del subsintema) è correlabile con quella dell’ultima fase di stazionamento alto del livello marino del pleistocene medio (ois 7). la località-tipo proposta è l’area di tommaso natale (monti di palermo) dove, su una piattaforma di abrasione marina localizzata a circa 45-50 m s.l.m., si hanno i depositi costieri datati da hearty et al. (1986). 5.2.3. considerazioni la formazione del sintema di partinico sembra essere collegata all’interazione tra oscillazioni del livello 354 c. di maggio et al. del mare (dovute a variazioni climatiche) e graduale e generalizzata tendenza al sollevamento della sicilia nord-occidentale. la combinazione di questi due fattori ha determinato, lungo le aree costiere, la formazione di superfici di abrasione marina e di falesie che, al succedersi di ogni fase di stazionamento alto del mare, si sono ciclicamente ripetute a quote via via inferiori a causa del progressivo innalzamento tettonico della regione in esame; si è così prodotta una gradinata di più ordini di terrazzi marini emersi, con superfici ricoperte da sedimenti. il ritrovamento a quote differenti, lungo le varie aree di affioramento, della superficie e del margine interno di uno stesso ordine di terrazzo marino (antonioli et al., 1999; di maggio et al., 1999; di maggio, 2000) consente di ipotizzare l’esistenza sia di settori che si sono sollevati con tassi di velocità diversi, sia di blocchi tettonici variamente dislocati. i tassi medi di sollevamento riferibili al pleistocene medio sono generalmente valutati tra 0,11 e 0,14 m/ka (mauz et al., 1997; antonioli et al., 1998; di maggio et al., 1999). il rinvenimento di depositi colluviali pedogenizzati all’interno di cavità carsiche nei settori più interni dell’area studiata, è invece indicativo del proseguimento della fase di continentalità di queste regioni. 5.3 sintema di polisano la successione dell’unità è costituita da arenarie e sabbie eoliche di natura prevalentemente quarzosa e in subordine calcarea, variamente cementate, a stratificazione e laminazione incrociata (fig. 7). tali depositi si rinvengono in facies sia di duna di ostacolo, addossati contro pareti montuose, sia di duna costiera, conservando l’originaria forma. nelle dune di ostacolo gli accumuli sabbiosi mostrano, al loro interno, inclusioni di elementi detritici sparsi, di varie dimensioni, derivanti da processi di degradazione, caduta di detrito e crollo dai sovrastanti versanti montuosi; intercalazioni di livelli ben definiti e relativamente più continui, formate da accumuli caotici di grossi massi frammisti a materiale litoide più fine, a giacitura caotica e dello spessore di qualche metro, sono invece riconducibili a locali fenomeni di crollo. lo spessore varia da pochi ad una decina di metri. il contenuto fossilifero è dato da rari gusci di gasteropodi polmonati. affiora in modo discontinuo, con corpi sedimentari isolati, lungo le aree costiere pianeggianti e a ridosso dei principali versanti montuosi rivolti verso mare. il limite inferiore, ubicato a differenti quote, è in parte una superficie di non deposizione al tetto dei depositi del subsintema di tommaso natale e in parte una superficie di erosione subaerea, incisa su terreni più antichi, marcata da chiare discordanze angolari e talvolta da paleosuoli. lo stesso limite è stato riconosciuto nella piana di castelluzzo, in località case polisano (penisola di capo san vito) e nel versante orientale di monte gallo (monti di palermo). in questi siti affiorano depositi eolici del sintema in oggetto che da una parte ricoprono una superficie (limite inferiore) al tetto di accumuli di terrazzo marino del subsintema di tommaso natale e, dall’altra, sono tagliati da superfici di erosione (piattaforme e falesie, coincidenti con il limite superiore) di età “eutirreniana” (sensu bonifay & mars, 1959), correlabile all’età dell’ois 5e, in quanto queste superfici sono ricoperte da depositi a strombus bubonius. anche nella piana di carini, a sferracavallo e montagna raffo rosso (monti di palermo) i depositi del sintema di polisano sono a luoghi incisi da superfici di erosione marina o subaerea dell’ois 5e. sulla base dei rapporti geometrici, l’età di questi depositi è da riferire all’ois 6, mentre il limite inferiore va collocato fra la fine dell’ois 7 e l’inizio dell’ois 6. la località-tipo proposta è l’area di case polisano (piana di castelluzzo) dove affiorano arenarie di duna costiera che, verso mare, sono intagliate da piattaforme e ripe marine dell’ois 5 e che, verso monte, ricoprono un terrazzo marino e i relativi depositi del subsintema di tommaso natale, questi ultimi correlabili all’ois 7. 5.3.1 considerazioni i depositi eolici del sintema vengono considerati tipici di un evento climatico glaciale e probabilmente arido (cfr. hugonie, 1979; 1982; ulzega & hearty, 1986; cremaschi & trombino, 1998; d’orefice et al., 2007); durante questo evento il vento asportava grandi quantità di materiali fini e sciolti dalle piattaforme appena emerse, accumulandole lungo le aree costiere pianeggianti (dune di retrospiaggia) oppure rilasciandole ai piedi dei versanti prospicienti le fasce costiere (dune di ostacolo). gli accumuli eolici del sintema di polisano ricoprono superfici e depositi del subsintema di tommaso natale (correlabili all’ois 7) e sono incisi da una superficie di erosione dell’ois 5e; la posizione stratigrafica induce a riferire questi depositi al penultimo evento climatico glaciale del quaternario, correlabile 355 fig. 7 versante meridionale di monte gallo. sintema di polisano: arenarie eoliche a laminazione e stratificazione incrociata. southern slope of monte gallo. polisano synthem: aeolian arenites with cross-bedded stratification/lamination. unità a limiti inconformi utilizzate per la cartografia dei depositi ... con l’ois 6. il limite inferiore del sintema (superficie di non deposizione e di erosione subaerea) coincide con segmenti sepolti dell’antica superficie topografica precedente l’evento glaciale in esame; assume quindi un significato climatico. gli accumuli detritici intercalati fra i depositi eolici, prodotti da processi sia di degradazione fisica delle rocce sia gravitativi, ne confermerebbero il significato in quanto indicativi di un evento di recrudescenza climatica. 5.4 sintema di barcarello l’unità raggruppa depositi costieri e continentali. tra gli sporadici depositi costieri si riconoscono: a) arenarie e sabbie fossilifere a laminazione piano parallela o incrociata, di spiaggia sommersa; b) conglomerati poligenici ed eterometrici arrossati, con elementi litoclastici e in subordine bioclastici, a scarsa (o del tutto assente) matrice ruditica fine o arenitica e supporto granulare, di ambiente di spiaggia intertidale; c) biolititi a vermetidi, di mare basso; d) brecce cementate con blocchi e ciottoli angolosi, a giacitura caotica, con scarsa e sporadica matrice arenitica (depositi di tempesta). lo spessore massimo raggiunto è di un paio di metri. i depositi continentali, di natura colluviale, sono: a) arenarie terrose e suoli rimaneggiati da ben cementati a scarsamente coesi, talvolta con tasche di riassorbimento, frequenti tracce di bioturbazione e presenza di aggregati argillosi ricchi in ossidi di ferro; b) livelli a clasti o blocchi angolosi e alterati, immersi in una ricca matrice terrosa e pelitica fine con tracce di pedorelitti (di maggio et al., 1999; boschian, 2002) e con concrezioni carbonatiche nodulari, a supporto fangoso, allineati a formare orizzonti debolmente inclinati (stone line); c) brecce detritiche fossilifere, da scarsamente a ben cementate, ricche di clasti litoidi angolosi di dimensioni da centimetriche a decimetriche e incrostati da ossidi di ferro e/o manganese, a struttura fangosa o granulare, con matrice terrosa o sabbiosa; d) peliti rossastre fini (“terre rosse” rimaneggiate) a laminazione piano-parallela, e) arenarie e sabbie eoliche o di spiaggia rimaneggiate, con inclusioni di elementi ruditici da angolosi a sub-arrotondati, con matrice terrosa. questi depositi sono incisi da locali superfici di erosione subaerea, prodotte dal dilavamento. il loro spessore medio è di circa 2-3 m, con valori massimi dell’ordine dei 5 m. le frequenti interdigitazioni fra i depositi costieri e i terreni continentali, riconosciute in alcune aree costiere come a case ferriato (penisola di capo san vito, fig. 8) e nelle località barcarello e la cala (monti di palermo), testimoniano una loro sostanziale contemporaneità di deposizione. deformazioni da locali faglie a componente trascorrente vengono indicate da abate et al. (1998) e nigro et al. (2000). i depositi marino-paralici contengono faune banali ma anche importanti ospiti senegalesi, quali vermetidi, echinidi, alghe, coralli, lamellibranchi (ostrea edulis, hyotissa hyotis, glycimeris glycimeris, spondylus gaederopus) e gasteropodi (patella ferruginea, cerithium lividulum lividulum, cerithium vulgatum, strombus bubonius, mitra fusca, conus mediterraneus, conus testudinarius, cantharus viverratus). i depositi continentali sono caratterizzati da livelli con abbondanti gusci di gasteropodi polmonati e resti di vertebrati appartenenti al complesso faunistico ad elephas mnaidriensis (sensu burgio & cani, 1988; bonfiglio et al., 2002 con bibliografia) datato al tardo pleistocene medio pleistocene superiore. il sintema si estende nella fascia costiera della sicilia nord-occidentale, lungo le fasce pedemontane delle aree collinari e montuose e all’interno di grotte e depressioni carsiche. il suo limite inferiore è una piattaforma di abrasione marina (fig. 9) pressoché ininterrotta, localizzata fra l’attuale livello del mare e le quote comprese fra 7 e 25 m s.l.m.; nelle aree più interne la stessa passa ad una discontinua superficie di erosione subaerea (fig. 10), elaborata da processi di dilavamento. il passaggio fra la piattaforma di abrasione marina e la superficie di erosione subaerea, non osservabile sul terreno, è stato desunto sulla base delle eteropie laterali fra depositi costieri e depositi continentali. il riconoscimento dei rapporti fra superfici di erosione subaeree / depositi a vertebrati e superfici di erosione marina / depositi a strombus bubonius, consente di riferire sia la parte basale dei depositi marino-paralici e dei depositi colluviali ad essi correlati, sia le sottostanti superfici di erosione subacquee e subaeree (limite inferiore), all’ois 5e. il rinvenimento di più recenti conglomerati e arenarie di spiaggia, poggiati su una piattaforma di abrasione marina di rango inferiore situa356 fig. 8 – case ferriato. sintema di barcarello: bcm arenarie di spiaggia; bccl suoli rimaneggiati con livelli di ciottoli allineati (ca). case ferriato. barcarello synthem: bcm coastal arenites; bccl reworked soils with stone lines (ca). c. di maggio et al. ta fra 0 e 3 m s.l.m. e intagliata su depositi e superfici dell’ois 5e, consente di datare la parte alta dei depositi del sintema al “neotirreniano” (sensu bonifay & mars, 1959), ossia al periodo di tempo correlabile con l’ois 5c o 5a (cfr. buccheri, 1966; di maggio et al., 1999; cottignoli et al., 2002). l’unità dovrebbe quindi ricoprire l’intervallo di tempo correlabile con l’intero ois 5. la località-tipo proposta è l’area di barcarello (sferracavallo), dove affiorano depositi di spiaggia, contenenti strombus bubonius, interdigitati con depositi colluviali e poggiati su una piattaforma di abrasione marina intagliata in calcari mesozoici. 5.4.1 considerazioni la formazione del limite inferiore del sintema di barcarello è riconducibile all’ultimo evento climatico caldo del pleistocene (ois 5e) durante il quale: a) lo stazionamento della superficie del mare nel tempo, ad una quota di circa 5-7 m superiore rispetto al livello marino attuale (b l o o m & yonekura, 1985; radtke, 1989), ha prodotto una piattaforma di abrasione marina (oggi limite inferiore dei depositi costieri); b) una fase morfogenetica dominata da importanti processi di dilavamento, probabilmente favoriti da un periodo relativamente lungo di semiaridità, ha contribuito alla formazione di una superficie di erosione subarea (oggi limite inferiore dei depositi continentali). l’attuale rinvenimento della piattaforma di abrasione da 0 m s.l.m. fino a quote comprese fra 7 e 25 m s.l.m. (margine interno) è indicativo di aree che, a partire dal tempo corrispondente all’ois 5e, si sono sollevate con tassi differenti compresi fra 0 (aree stabili) e 0,2 m/ka (cfr. co s e n t i n o & gliozzi, 1988; mauz et al., 1997; antonioli et al., 1999; di maggio et al., 1999; di maggio, 2000). i depositi colluviali, costituiti da suoli rimaneggiati e materiali detritici più o meno grossolani, testimoniano l’alternarsi di condizioni climatiche ora favorevoli alla pedogenesi, ora favorevoli alla degradazione fisica delle rocce e allo sviluppo di sporadici ma intensi eventi di erosione idrica diffusa. la presenza di superfici di erosione di rango inferiore (piattaforma di abrasione marina fra 0 e 3 m s.l.m. e locali superfici di erosione subaerea) è prova di un successivo stazionamento marino a quote inferiori, rispetto a quello dell’ois 5e, e di eventi di ruscellamento particolarmente intensi. questi ultimi sono responsabili anche del trasporto di materiale colluviale fino alle aree costiere allora sommerse. 5.5 sintema dell’imera settentrionale i corpi rocciosi che costituiscono questo sintema appartengono a più ordini di terrazzi fluviali, ubicati all’’interno delle vallate principali e distribuiti da pochi fino ad un centinaio di metri di dislivello rispetto ai fondovalle attuali. i depositi alluvionali hanno geometria tabulare e sono costituiti da prevalenti livelli di ghiaie e/o conglomerati poligenici e di arenarie, sabbie e silt. gli spessori massimi raggiunti, nel caso dei terreni appartenenti agli ordini più recenti, sono di 3 m. nei depositi alluvionali di un terrazzo fluviale sito in vicinanza della foce del fiume imera settentrionale, sospeso ad una decina di metri di altezza sul fondovalle, sono stati rinvenuti resti di hippopotamus pentlandi (battaglia & ciofalo, 1883) appartenenti al complesso 357 fig. 9 – estremità nord-occidentale della penisola di capo san vito. limite inferiore del sintema di barcarello (sm piattaforma di abrasione marina) situato a 2-3 m s.l.m., intagliato su carbonati mesozoici (sb) e ricoperto da conglomerati di spiaggia (bcm); seguono detriti di falda (cpd) e ciottoli di spiaggia (cpm) del sintema di capo plaia. north-western end of penisola di capo san vito. lower boundary of the barcarello synthem (sm – wave-cut platform) located at 2-3 m a.s.l., carved on mesozoic carbonate rock (sb) and covered by coastal conglomerates (bcm); talus breccias (cpd) and coastal pebbles (cpm) of capo plaia synthem follow. fig. 10 – versante occidentale di montagna raffo rosso. limite inferiore del sintema di barcarello (sc – superficie di erosione idrica), inciso su depositi eolici del sintema di polisano (ps) e ricoperto da detriti e suoli rimaneggiati (bc). western slope of montagna raffo rosso. lower boundary of barcarello synthem (sc – water erosion surface) incised on the aeolian deposits of polisano synthem (ps) and covered by reworked breccias and soils (bc). unità a limiti inconformi utilizzate per la cartografia dei depositi ... faunistico ad elephas mnaidriensis (tardo pleistocene medio pleistocene superiore). mauz et al. (1997) effettuano datazioni con il metodo della termoluminescenza su campioni di un conglomerato sterile. tale conglomerato, erroneamente scambiato da questi autori per un deposito di terrazzo marino, è in realtà un deposito di un terrazzo fluviale. esso è infatti localizzato all’interno della valle fluviale del fiume iato, in un tratto in cui il corso d’acqua attraversa, tagliandola, la piana di partinico; risulta sospeso, lungo il versante in destra idrografica, ad una altezza di circa 15 m rispetto al fondovalle. i risultati di questa datazione restituiscono un’età di 227 +/40 ka. depositi alluvionali, ben conservati su piani di erosione laterale appartenenti a vari ordini di terrazzi di erosione in roccia, affiorano “sospesi” rispetto ai fondovalle lungo alcuni settori dei bacini idrografici dei fiumi pollina, imera settentrionale (fig. 11), san leonardo e belice. il limite inferiore del sintema, riferibile al terrazzo fluviale più antico riconosciuto nella sicilia nord-occidentale, è una superficie di erosione laterale, incisa su rocce pre-quaternarie, localizzata lungo la valle del fiume imera settentrionale, a circa 230 m s.l.m. e a un centinaio di metri di altezza rispetto al fondovalle. discordanze di rango inferiore sono presenti ad altezze inferiori dai fondovalle. l’età del limite inferiore del sintema viene qui correlata alla parte inferiore del pleistocene medio sulla base di alcune considerazioni ed osservazioni: 1) le valli fluviali dei corsi d’acqua tirrenici si sono verosimilmente individuate a causa di processi di approfondimento ed erosione regressiva successivi alla tettonica distensiva del pleistocene inferiore; 2) le superfici dei terrazzi e i relativi depositi appaiono preservati solo nelle porzioni medio basali dei versanti vallivi, costituendo forme relativamente recenti; 3) l’apporto dei dati paleontologici e radiometrici. i depositi dei differenti ordini di terrazzi dovrebbero invece ricoprire un intervallo di tempo che va dal pleistocene medio al pleistocene superiore. sulla base di queste considerazioni, il sintema dell’imera settentrionale è correlabile con i sintemi della piana di partinico, di polisano e di barcarello. tuttavia l’assenza di continuità laterale tra questi sintemi, la difficile identificazione all’interno dei depositi del sintema dell’imera settentrionale dei limiti inferiori dei sintemi di polisano e barcarello e la metodologia di rilevamento suggerita dal servizio geologico d’italia (2001) hanno indotto gli autori a definire questa distinta ubsu. la località-tipo proposta si rinviene lungo il tratto di valle del fiume imera settentrionale tra cozzo gracello e monte riparato, dove si riconoscono almeno tre ordini di terrazzi fluviali, con i relativi depositi, distribuiti da 5-7 m a poco più di 100 m di altezza rispetto all’attuale fondovalle. 5.5.1 considerazioni la genesi dei diversi ordini di superfici di erosione fluviale (limite inferiore e discontinuità di rango minore) è verosimilmente da ricondurre a fasi di stazionamento alto del livello marino (corrispondente al livello di base fluviale) del pleistocene medio; durante queste fasi (coincidenti con eventi climatici caldi) dovevano svilupparsi processi di sovralluvionamento delle valli, successivamente seguite da fasi di erosione laterale/sedimentazione; durante queste ultime si producevano le pianure di erosione laterale su cui attualmente si rinvengono i depositi alluvionali sospesi. in corrispondenza di fasi di stazionamento basso del mare (durante eventi climatici freddi) dovevano invece prevalere processi di erosione di fondo, con l’abbandono dei vecchi depositi a quote superiori. l’alternarsi di queste fasi e la loro interazione con la tendenza generalizzata al sollevamento della sicilia nord-occidentale, ha fatto sì che i processi di erosione abbiano prevalso sui processi di sedimentazione (predominio dell’approfondimento fluviale sul sovralluvionamento delle valli) e che l’attuale assetto stratigrafico sia caratterizzato da terrazzi fluviali (e relativi depositi) più antichi distribuiti a quote più elevate rispetto a terrazzi fluviali (e relativi depositi) più recenti. 5.6 sintema di raffo rosso il corpo sedimentario è formato da potenti pacchi di detrito stratificato e cementato e da depositi eolici, entrambi tipici di un evento climatico freddo e probabilmente arido, e da isolati accumuli di origine colluviale e gravitativa, con livelli pedogenizzati. i detriti stratificati e cementati, di falda detritica (fig. 12), sono organizzati in più livelli ben classati di spessore variabile da 0,5 a 2 m, con scheletro granosostenuto a clasti da molto angolosi a sub-arrotondati del diametro medio di 0,5-20 cm e massimo di 50 cm, con matrice assente o molto scarsa; a luoghi si riconoscono intercalazioni di blocchi e clasti eterometrici a giacitura caotica, interpretabili come accumuli di crollo. i depositi eolici, di ambiente di duna costiera, sono costituiti da sabbie ed arenarie quarzose o calcaree, con tracce di stratificazione e laminazione incrociata. 358 fig. 11 – versante vallivo del fiume imera settentrionale (pressi di monte riparato): cp depositi colluviali (sintema di capo plaia); im conglomerati fluviali (sintema dell’imera settentrionale); sf superficie di erosione fluviale (posta a circa 10 m dal fondovalle); sb substrato clastico miocenico. valley slope of fiume imera settentrionale (near monte riparato): cp colluvial deposits (capo plaia synthem); im fluvial conglomerates (imera settentrionale synthem); sf stream erosion surface (located at about 10 m above valley bottom); sb miocene clastic substrate. c. di maggio et al. i depositi colluviali e gravitativi sono rappresentati da: a) brecce ad elementi ruditici (detriti di falda rimaneggiati); b) sabbie limose, limi argillosi e limi sabbiosi (suoli rimaneggiati) con presenza di concrezioni carbonatiche nodulari e di livelli a blocchi, ciottoli e ciottoletti allineati (stone line); c) limi sabbiosi con abbondanti pedorelitti; d) livelli a blocchi immersi in limi sabbiosi (depositi da debris flow). gli spessori complessivi sono dell’ordine di una decina di metri per i detriti stratificati e cementati, di circa 1-2 m per le eolianiti e di 1-7 m per i depositi colluviali e gravitativi. il contenuto fossilifero, rinvenuto nei depositi colluviali, è costituito da molluschi continentali e da un’associazione di mammiferi riferibili ai complessi faunistici di pianetti e di castello (bonfiglio et al., 2002 con bibliografia) del pleniglaciale – tardiglaciale (75-10 ka). datazioni con la termoluminescenza condotte da mauz et al. (1997) su sabbie quarzose eoliche affioranti nella piana di partinico, hanno restituito età correlabili con gli ois 4-2. i detriti si rinvengono ai piedi di scarpate e versanti rocciosi fortemente inclinati, i depositi eolici lungo le aree costiere pianeggianti e i depositi colluviali in corrispondenza di versanti o all’interno di grotte carsiche o marine e, più genericamente, di depressioni di varia origine. il limite inferiore del sintema è in parte una superficie di non deposizione, coincidente con il tetto dei depositi del sintema di barcarello, ed in parte una preesistente superficie di erosione subaerea, incisa su terreni ancora più antichi e a luoghi marcata da paleosuoli. all’interno delle successioni detritiche e colluviali si rinvengono discontinuità di rango inferiore, anche queste contrassegnate da paleosuoli. l’età dei corpi sedimentari viene riferita all’ultimo evento climatico freddo del quaternario (ois 4-2) sulla base dei rapporti geometrici fra il sintema di raffo rosso e il sintema di barcarello, dell’ambiente di sedimentazione dei depositi in esame e con l’ausilio delle informazioni paleontologiche e radiometriche. la superficie di non deposizione basale (limite inferiore) viene collocata all’inizio dell’evento climatico citato e, più specificamente, alla base dell’ois 4. la località-tipo proposta è il versante occidentale di montagna raffo rosso dove, all’interno di una grande cava, è stata portata alla luce una spessa successione di detriti stratificati e cementati poggiata sui depositi colluviali del sintema di barcarello. 5.6.1 considerazioni la genesi della superficie basale e dei depositi del sintema di raffo rosso è da ricondurre all’innesco di intensi processi di degradazione, favoriti da condizioni climatiche fredde, e di processi eolici, favoriti dall’abbassamento del livello marino e dall’emergere di accumuli sabbiosi prima sommersi; questi processi hanno prodotto, rispettivamente, l’accumulo di notevoli quantità di detriti ai piedi dei versanti e la deposizione di sabbie eoliche lungo le aree costiere, con il conseguente seppellimento di alcuni tratti dell’antica superficie topografica (limite inferiore del sintema) presente all’inizio dell’ultimo evento glaciale. 5.7 sintema di capo plaia il sintema raggruppa: a) depositi alluvionali che poggiano su piani di erosione laterale o che riempiono parzialmente preesistenti valli a “v” (superfici di erosione fluviale), queste ultime prodotte da processi di approfondimento e di erosione regressiva dei corsi d’acqua a seguito dell’abbassamento del livello marino durante l’ultimo evento climatico freddo del quaternario; b) depositi ciottolosi e/o sabbiosi di spiaggia che ricoprono, lungo le coste, superfici di erosione subaerea o di non deposizione, talvolta pedogenizzate, a seguito della loro sommersione per la risalita olocenica del mare; in altri casi i depositi di spiaggia poggiano sull’attuale piattaforma di abrasione marina, in via di formazione; c) più cicli di depositi colluviali disposti lungo pendii a componente argillosa o in tratti di versante costituiti da detriti, poggiati su superfici di erosione subaerea prodotte dal dilavamento; d) detriti di falda e accumuli di crollo deposti ai piedi dei versanti su superfici di non deposizione o di erosione subaerea; e) corpi di frana e depositi gravitativi in genere poggiati lungo locali superfici di distacco o superfici di separazione. in relazione alla loro recente età (fine pleistocene superiore – attuale), i terreni di questo sintema costituiscono i depositi più diffusi e di maggiore estensione. il limite inferiore è dato da superfici di varia genesi, fra loro comunque correlabili, che hanno avuto origine durante l’ultima fase di risalita del mare, al passaggio fra il pleistocene superiore e l’olocene (ois 2-1). superfici di inconformità di rango inferiore, di età olocenica, interessano a varie altezze stratigrafiche i depositi del sintema. il limite superiore è l’attuale superficie topografica. la località-tipo proposta è una sezione lungo il versante nord-occidentale di poggio maria (area di capo plaia), dove è esposto un pacco di depositi colluviali olocenici. questi depositi si sovrappongono a detriti stratificati e cementati del sintema di raffo rosso lungo una superficie di erosione subaerea scavata dalle acque dilavanti. 359 fig. 12 – versante occidentale di montagna raffo rosso. detriti stratificati e cementati (sintema di raffo rosso). western slope of montagna raffo rosso. stratified slope deposits (raffo rosso synthem). unità a limiti inconformi utilizzate per la cartografia dei depositi ... 6. conclusioni lo studio dettagliato dei depositi marini, paralici e continentali del quaternario della sicilia nord-occidentale condotto nell’ambito del progetto carg, ha consentito sia di definire un quadro organico e sintetico delle successioni di terreni qui affioranti, sia di riconoscere, al loro interno, numerose superfici di discontinuità, alcune delle quali di importanza regionale. le superfici di importanza regionale, alcune essenzialmente continue altre frammentarie ma correlabili anche a grande distanza, hanno a loro volta permesso la definizione di sette ubsu del rango di sintema che ricoprono un arco di tempo che va dal pleistocene inferiore all’attuale (figg. 4, 13). questi sintemi sono rappresentativi dei depositi quaternari della sicilia nord-occidentale; essi sono stati cartografati in numerosi fogli geologici 1:50.000 del progetto carg in fase di allestimento per la stampa (figg. 1 e 2). l’analisi dei corpi rocciosi e dei limiti inconformi suggeriscono importanti cambiamenti ambientali nella sicilia nord-occidentale durante il quaternario (agnesi et al., 1998; agnesi et al., 2000b). questi cambiamenti possono essere ritenuti cause (dirette o indirette) dell’innesco di peculiari processi di erosione e/o sedimentazione responsabili della genesi delle discontinuità di importanza regionale e dei corpi sedimentari riconosciuti. importanti eventi tettonici di fagliazione a blocchi o sollevamento, brusche fluttuazioni climatiche o l’interazione di eventi tettonici e climatici, sono i fattori principali all’origine delle modificazioni ambientali. un evento tettonico del pleistocene inferiore, responsabile della genesi di faglie a forte componente distensiva (rigetti verticali dell’ordine del centinaio di metri) e del conseguente ribassamento, al di sotto del livello del mare, di alcuni grandi blocchi della sicilia settentrionale, sembra il fattore che ha consentito l’innesco di processi di erosione, sommersione e, al tempo stesso, di sedimentazione marina, che hanno prodotto, rispettivamente, la piattaforma di abrasione, l’annegamento di originarie superfici di erosione subaerea e i sovrastanti depositi del sintema di marsala. eventi climatici freddi, con il livello marino stabilizzato a quote inferiori rispetto all’attuale, sono le cause che hanno consentito potenti accumuli di depositi eolici e di detriti stratificati e cementati dei sintemi di polisano e di raffo rosso. in entrambi i casi, questi depositi poggiano su superfici di non deposizione coincidenti con le antiche superfici topografiche della fase iniziale degli eventi freddi. eventi climatici essenzialmente semiaridi hanno favorito lo sviluppo di processi di dilavamento e la produzione di quantità più o meno abbondanti dei depositi colluviali costituenti parte dei sintemi di marsala, della piana di partinico, di barcarello e di raffo rosso; nel caso del sintema di barcarello, il dilavamento ha assunto un’importanza tale da produrre una superficie di erosione subarea di estensione regionale. tali processi hanno anche contribuito allo smantellamento o alla parziale rielaborazione di preesistenti sedimenti ancora sciolti o poco cementati; questo meccanismo spiegherebbe l’assenza di detriti cementati e stratificati e, più in generale, di altri accumuli continentali riferibili a più antichi eventi climatici freddi o caldi del pleistocene medio. l’interazione fra movimenti tettonici di sollevamento e fasi di stazionamento alto del mare è invece responsabile della formazione dei diversi ordini di terrazzi marini e di terrazzi fluviali, che si sviluppano dalle maggiori alle minori quote e sulle cui superfici giacciono i corpi sedimentari dei sintemi della piana di partinico, di barcarello e dell’imera settentrionale. l’ultima risalita del livello del mare e le condizioni climatiche attuali hanno determinato lo sviluppo della superficie limite inferiore e l’accumulo dei depositi del sintema di capo plaia. ringraziamenti ricerca condotta con fondi: prin miur 2006 e carg (r. catalano); prin miur 2007 e fondi di ateneo 2005, 2006 e 2007 dell’università degli studi di palermo (v. agnesi). si ringraziano i referee maurizio d’orefice e un anonimo per l’attenta lettura del manoscritto, le critiche pertinenti, le puntuali osservazioni e gli utili suggerimenti che hanno contribuito alla stesura definitiva del lavoro. 360 fig. 13 rapporti tra le unità a limiti inconformi della sicilia nord-occidentale: 1. sintema di capo plaia (stadi isotopici 2-1); 2. sintema di raffo rosso (stadi isotopici 4-2); 3. sintema di barcarello (stadio isotopico 5); 4. sintema di polisano (stadio isotopico 6); 5. sintema della piana di partinico (pleistocene medio); 6. sintema dell’imera settentrionale (pleistocene medio e superiore); 7. sintema di marsala (pleistocene inferiore); 8. substrato pre-quaternario. geometric relationships among unconformity-bounded stratigraphic units of nw sicily. 1. capo plaia synthem (isotope stages 2-1); 2. raffo rosso synthem (isotope stages 4-2); 3. barcarello synthem (isotope stage 5); 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(1995) new data on the evolution of pliocene climatic variability in: vraba e. et al. (eds.) palaeoclimate and evolution, yale university press, pp. 242-248. tongiorgi e. & trevisan l. (1953) – excursion en sicile iv int. congr. inqua, livret guide, 34 pp. ulzega a. & hearty p. j. (1986) geomorphology, stratigraphy and geochronology of late quaternary marine deposits in sardinia zeitschrift für geomorphologie supplement band, 62, pp. 119-129. vaufrey r. (1929) les éléphants nains des iles méditerranéens et la question des isthmes pléistocènes arch. dell’ inst. de paleont. humaine, memoire, 6, 220 pp. 363 ms. ricevuto il 27 aprile 2009 testo definitivo ricevuto il 10 luglio 2009 ms. received: april 27, 2009 final text received: july 10, 2009 unità a limiti inconformi utilizzate per la cartografia dei depositi ... imp.bianca-caputo aannaalliissii mmoorrffootteettttoonniiccaa eedd eevvoolluuzziioonnee qquuaatteerrnnaarriiaa ddeellllaa vvaall dd’’aaggrrii,, aappppeennnniinnoo mmeerriiddiioonnaallee mmaarrcceelllloo bbiiaannccaa && rriiccccaarrddoo ccaappuuttoo di.s.g.g., università della basilicata, campus macchia romana, 85100, potenza, italia riassunto sulla base di una dettagliata indagine morfologica dei terrazzi fluviali e marini che caratterizzano la val d'agri (italia meridionale), è stato possibile ricostruire l'evoluzione morfotettonica quaternaria di questo settore dell'appennino meridionale. i risultati ottenuti permettono di suddividere la valle in tre settori a diversa evoluzione morfotettonica, separati da due evidenti soglie morfostrutturali coincidenti con altrettante importanti strutture tettoniche. il settore più occidentale, rappresentato dall’alta val d’agri, è compreso tra la sorgente ed il sovrascorrimento dell’armento. l’evoluzione morfotettonica e sedimentaria tardo-quaternaria di questo tratto vallivo è stata principalmente controllata dalla persistenza, durante il pleistocene, di una soglia rappresentata da un’estesa anticlinale con asse nno-sse, strutturalmente associata al sovrascorrimento dell’armento e responsabile della formazione del 'paleolago' del pertusillo. la presenza, a quote prossime al corso attuale dell’agri, di due ordini simmetrici di terrazzi alluvionali (il più recente dei quali è attualmente sommerso dal lago artificiale del pertusillo), attribuibili al pleistocene superiore-olocene, suggerisce altrettante fasi discrete di sollevamento tettonico che potrebbero essere il risultato dell’attività recente di una o più faglie bordiere dell’alta val d’agri. la media val d’agri è invece impostata sulle successioni clastiche marine e continentali plio-pleistoceniche del bacino di sant’arcangelo ed è confinata tra il sovrascorrimento dell’armento e un’altra soglia, anch’essa di origine tettonica, rappresentata dalla faglia di scorciabuoi. la proiezione longitudinale dei quattro ordini di terrazzi fluviali medio-suprapleistocenici rilevati lungo la riva destra dell’agri, nel settore dell’abitato di sant’arcangelo, evidenzia che questo versante è stato interessato, nel tardo quaternario, da un processo di sollevamento e di piegamento antiforme, che suggerisce un’attività recente della faglia di scorciabuoi o di un’eventuale struttura contrazionale sepolta. infine, la bassa val d’agri, compresa tra la faglia di scorciabuoi e la costa ionica, è caratterizzata dalla presenza di terrazzi sia fluviali che marini. la buona correlazione fisica tra i terrazzi marini, sviluppati trasversalmente alla foce dell’agri, e i terrazzi fluviali presenti lungo il tratto più basso del fiume, conferma l’influenza predominante dell’eustatismo nell’evoluzione morfologica di questa porzione della valle. l’analisi morfotettonica della distribuzione dei terrazzi marini del pleistocene medio-superiore ha evidenziato che il settore costiero della foce dell’agri è stato interessato da un sollevamento tettonico quaternario non uniforme nello spazio e nel tempo, caratterizzato da tassi compresi tra 0,03 mm/a e 2,76 mm/a. abstract the agri river extends for about 100 km from the axial zone of the southern apennines to the ionian coast of the basilicata region, southern italy, flowing with a mean e-w direction and crossing both the internal and external geological domains of the ne-verging fold-and-thrust apennines belt. the agri valley develops along one of the most tectonically active regions of southern italy, which has been struck by recurrent and large seismic events in historical times, such as the 1857 basilicata earthquakes. based on the great sensitivity of the alluvial rivers to the variations in topographical gradient, a morphotectonic analysis has been carried out on the quaternary alluvial, erosional and marine terraces occurring along and at the mouth of the agri river. the preliminary results allow us to divide the agri valley into three reaches (sectors a, b and c), bounded by two major tectonic structures, the armento thrust and the scorciabuoi fault and characterized by different deformation and morphogenic processes. the orders of terraced surfaces have been labelled with roman numbers, starting from the youngest and lowest terrace (i) to the older ones. except terrace i that has been observed throughout most of the valley, all other terraces are followed by a letter, indicating the sector of the agri valley where they occur (a, b or c) if of fluvial origin, or by the letter "m" when they represent marine terraces. the quaternary morphological and sedimentary evolution of high agri valley (sector a) has been controlled mainly by the persistence, until present time, of an important threshold occurring at the nucleus of the anticline associated to the e-verging armento thrust. during the middle-late pleistocene, the beginning of the entrenchment of the threshold caused the progressive outpouring of the ancient pertusillo lake, previously generated by the growing anticline, with the formation of the wide terrace (iii-a) representing the top of the lacustrine deposits. on the other hand, the alluvial terraces i and ii-a are possibly related to as many, probably fault-related, uplifting phases which occurred in late pleistocene-holocene time. the middle agri valley (sector b), crossing the middle pliocene-middle pleistocene s. arcangelo basin, is eastward bounded by the nwse-trending strike-slip scorciabuoi fault. four orders of asymmetrical middle pleistocene-holocene alluvial terraces, showing a clear antiform warping, have been recognized in this sector. the deformed terraces, together with the shifting of the entrenching channel toward the opposite northern bank of the river, suggest that the uplift and the warping processes are likely to be associated to a blind thrust or, alternatively, to the tectonic activity of the scorciabuoi fault. the occurrence of a seismogenic fault in the central part of the agri valley would account for the strong damages (i=x mcs) undergone by the villages of aliano and alianello during the 1857 basilicata earthquake (m=6.5). finally, the low agri valley (sector c) is characterized by the occurrence of both alluvial and marine terraces showing a good morphological correlation. the morphotectonic analysis of the marine terraced sequence, considered as the result of the interaction between tectonic uplift and middle-late quaternary eustatic changes, pointed out a non-uniform tectonic uplifting rate of the coastal area, the magnitude of which clearly decreases toward the front of the apennines orogenic belt. moreover, the vertical distribution of the palaeo-shorelines of the marine terraces allowed us to estimate uplift rates ranging from about 0.2 mm/a to more than 2.5 mm/a, which are more typical of fault activity rather than regional uplift. parole chiave: tettonica quaternaria; val d’agri; terrazzi fluviali e marini; tassi di sollevamento. keywords: : quaternary tectonics; agri valley; fluvial and marine terraces; uplift rates. il quaternario italian journal of quaternary sciences 1166(2), 2003, 159-170 iinnttrroodduuzziioonnee il fiume agri scorre in direzione circa e-o per oltre 100 km lungo il settore meridionale della basilicata, dalla zona assiale dell’appennino lucano fino alla costa del mar ionio, seguendo una direzione diagonale rispetto all’andamento della catena (fig. 1b). la val d’agri è quindi impostata su diversi domini geologici, passando dalle unità geologico-strutturali interne a quelle esterne dell’orogene appenninico fino ad attraversare, nel suo tratto finale, i depositi clastici dell’avanfossa bradanica (fig. 1b). questo settore di catena-avanfossa è stato caratterizzato da una complessa storia deformativa cominciata nel miocene inferiore, con la messa in posto 160 m. bianca & r. caputo marine è stato eseguito mediante l’analisi aerofotogrammetrica di strereocoppie a scala 1:33.000 dell’igm e verificato successivamente con dettagliate e specifiche indagini di terreno. i dati ottenuti sono stati così cartografati sulla base topografica a scala 1:25.000 dell’igm. la scarsa continuità laterale dei terrazzi fluviali, assieme alla mancanza di datazioni assolute, non ha consentito una correlazione univoca tra i diversi ordini terrazzati lungo l’intero corso dell’agri. tuttavia, la distribuzione areale dei dati raccolti mostra una continuità sufficiente per correlare i diversi ordini terrazzati all’interno dei tratti alto (settore a), mediano (settore b) e basso (settore c) della val d’agri (fig. 1). questi tre settori, separati da due importanti soglie coincidenti con altrettante strutture neotettoniche (sovrascorrimento dell’armento e faglia di scorciabuoi), si differenziano in base al diverso ruolo che i principali fattori morfogenici, ovvero i processi tettonici, climatici ed eustatici, hanno giocato nell’evoluzione geomorfologica di questa valle. l’influenza di questi diversi fattori sull’evoluzione della val d’agri dipende fortemente dalla scala cronologica in cui vengono analizzati. infatti, considerando che l’intervallo temporale analizzato abbraccia quasi l’intero quaternario, è possibile affermare che il processo continuo di sollevamento fig. 1 a: localizzazione regionale dell’area attraversata dalla val d’agri. b: schema geologico-strutturale del settore lucano dell’appennino meridionale. legenda: 1 = depositi clastici dell’avanfossa bradanica (pliocene-quaternario); 2 = depositi di flysch (miocene); 3 = unità lagonegresi (triassico inferiore-miocene medio); 4 = unità carbonatiche della piattaforma apula (mesozoicocenozoico); 5 = unità carbonatiche della piattaforma campano-lucana (mesozoico-cenozoico); 6 = sovrascorrimenti; 7 = faglie normali; 8 = faglie trascorrenti. c: carta morfotettonica schematica della val d’agri, in cui sono rappresentate le superfici terrazzate fluviali e marine (aree in grigio) con i rispettivi bordi interni e le due principali strutture tettoniche che segmentano la valle e che permettono di distinguere tre settori. a: southern italy map and location of the investigated area. b: geological-structural sketch of the lucanian apennines. legend: 1 = clastic deposits of the bradanic foredeep (pliocene-quaternary); 2 = flysch deposits (miocene); 3 = lagonegro units (lower triassicmiddle miocene); 4 = carbonates of the apulian platform (mesozoic-cenozoic); 5 = carbonates of the campania-lucania platform (mesozoic-cenozoic); 6 = thrust faults; 7 = normal faults; 8 = strike-slip faults. c: morphotectonic sketch of the agri valley, showing the fluvial and marine terraces (grey-coloured areas) with their inner edges and the main tectonic structures cutting the valley allowing the distinction of three sectors. dell’edificio a falde e-vergenti dell’appennino, e seguita da fasi tettoniche tardo-orogeniche testimoniate da diversi sistemi strutturali sia distensivi che trascorrenti. alcune di queste strutture sono ancora attive, come testimonia la forte sismicità storica di questa regione, colpita da numerosi eventi sismici ad alta energia, come il terremoto della basilicata del 1857. questo lavoro, che rappresenta un tentativo di analisi morfotettonica della val d’agri, è stato suddiviso in due fasi: nella prima fase sono state individuate e interpretate le principali morfostrutture fluviali e marine presenti rispettivamente lungo il corso del fiume agri e lungo il tratto costiero adiacente alla foce; nella seconda fase, invece, questi elementi morfologici sono stati utilizzati come elementi diagnostici degli eventi deformativi quaternari che hanno interessato questo settore della basilicata meridionale. a questo scopo, sono state applicate metodologie d'indagine basate prevalentemente sulla sensibilità dei fiumi alle variazioni del gradiente topografico, e sulla distribuzione dei terrazzi fluviali e marini presenti rispettivamente lungo il corso d’acqua principale e in corrispondenza della foce (schumm et al., 2000; burbank & anderson, 2001). il rilevamento delle superfici terrazzate fluviali e tettonico regionale, sebbene caratterizzato da tassi sicuramente variabili nel tempo, può essere considerato il fattore morfogenico preponderante nell’evoluzione della valle, rispetto ai processi ciclici come le variazioni climatiche ed eustatiche. a questo proposito, è importante sottolineare che un processo ciclico può lasciare una traccia morfologica in un sistema fluviale soltanto se il suo periodo di oscillazione è superiore al tempo di risposta del sistema fluviale stesso, che è generalmente nell’ordine di 103 anni (vandenberghe, 2002). di conseguenza, le variazioni climatiche comprese tra quelle stagionali e quelle millenarie non possono lasciare una traccia morfologica evidente lungo una valle fluviale. un ruolo morfogenico ben diverso hanno invece avuto le principali oscillazioni eustatiche quaternarie, in particolare lungo quei tratti del fiume agri che si trovavano in prossimità della paleolinea di costa. l’impatto morfogenico importante delle oscillazioni eustatiche è legato principalmente al loro lungo periodo di ciclicità (104-105 anni) e alla loro notevole escursione verticale (120-150 m tra un picco glaciale e un picco interglaciale). i diversi ordini di superfici fluviali, marine e continentali sono stati indicati mediante cifre romane, crescenti dagli ordini più bassi e recenti a quelli più elevati 161analisi morfotettonica ... e antichi. ognuno dei settori è ovviamente caratterizzato da una numerazione dei terrazzi fluviali autonoma, evidenziata dalla lettera del settore (a, b o c) che segue il numero romano, mentre i terrazzi d'origine marina sono indicati dalla lettera "m". a questa classificazione fa eccezione la superficie alluvionale più recente (terrazzo i), che è presente con una buona continuità laterale lungo l’intero corso dell’agri. e' da notare che lungo alcuni tratti tale superficie, che rappresenta sempre il tetto dei depositi fluviali più recenti, costituisce l’attuale letto di piena del fiume, mentre lungo altri tratti la stessa superficie appare sospesa rispetto al canale attuale, formando così il terrazzo fluviale più giovane tra quelli rilevati in questo studio. nelle sezioni successive del presente articolo, saranno descritti e discussi separatamente, da un punto di vista dell'evoluzione morfologica e fluviale, i tre settori in cui è stata suddivisa la valle del fiume agri. settore a: alta val d’agri l’alta val d’agri (fig. 2) attraversa il settore interno dell’appennino lucano che è costituito da un sistema a pieghe e sovrascorrimenti (fold-and-thrust system) ne-vergente strutturatosi tra il miocene inferiore fig. 2 carta morfotettonica dell’alta val d’agri (settore a). legenda: 1 = substrato delle superfici terrazzate e dei terrazzi fluviali quaternari; 2 = terrazzo fluviale i; 3 = terrazzo fluviale ii-a; 4 = terrazzo fluviale iii-a; 5 = superficie terrazzata iv-a; 6 = tratto fluviale inforrato; 7 = faglia diretta; 8 = sovrascorrimento; 9 = faglia trascorrente; 10 = traccia assiale di anticlinale; 11 = traccia assiale di sinclinale; 12 = bordo interno di terrazzo. morphotectonic map of the high agri valley (sector a). legend: 1 = substratum of the quaternary terraced surfaces and fluvial terraces; 2 = fluvial terrace i; 3 = fluvial terrace ii-a; 4 = fluvial terrace iii-a; 5 = terraced surface iv-a; 6 = fluvial canyon; 7 = normal fault; 8 = thrust fault; 9 = strike-slip fault; 10 = axial trace of anticline; 11 = axial trace of syncline; 12 = inner edge of terrace. (d’argenio et al., 1973) ed il pleistocene inferiore (carbone et al., 1991; cinque et al., 1993). i terreni coinvolti nella deformazione orogenica, prevalentemente mesozoici, appartengono sia alle unità lagonegresi (scandone, 1967), che alle unità di piattaforma carbonatica (scandone, 1971). nel settore orientale dell’alta val d’agri, il substrato mesozoico è ricoperto dai depositi flyschoidi miocenici delle formazioni di gorgoglione e albidona. questo settore della val d’agri è delimitato verso est da una soglia morfostrutturale rappresentata da una serie di rilievi localizzati tra l’abitato di montemurro e il torrente armento (fig. 2) e litologicamente costituiti dai terreni silicoclastici della formazione di gorgoglione. quest’area di soglia coincide con la zona assiale di una anticlinale con asse orientato nno-sse strutturalmente associata al sovrascorrimento dell’armento. questa struttura fa parte di una serie di sovrascorrimenti principali che caratterizzano il quadro strutturale dell’alta val d’agri e che mostrano una geometria generalmente arcuata con convessità verso est e con una direzione media n150°, coincidente con l’andamento dell’intera dorsale appenninica. il profilo longitudinale del canale attuale del fiume agri, infatti, conferma la presenza di una netta variazione di pendenza (knick-point) in corrispondenza della zona assiale di questa anticlinale (fig. 3), suggerendo che il processo di erosione regressiva, che dovrebbe portare il fiume a raggiungere il profilo di equilibrio ideale, è tuttora in corso. le principali strutture di tipo contrazionale sono dissecate ad alto angolo da diversi sistemi di faglie estensionali e trascorrenti, riferibili alle fasi tettoniche tardo-orogene del pleistocene. il più importante tra questi sistemi strutturali borda il bacino intramontano nel quale si sviluppa l’alta val d’agri ed è formato da faglie a direzione media n 120° (fig. 2), caratterizzate da una cinematica trascorrente sinistra durante il pleistocene inferiore e riattivate come faglie dirette durante il pleistocene medio (giano et al., 2000). il riempimento sedimentario del bacino è costituito da una successione clastica quaternaria, denominata 'complesso val d’agri' (di niro et al., 1992), caratterizzata da argille e limi lacustri alla base, che passano verso l’alto a depositi marcatamente fluviali, per terminare al tetto con uno spessore di depositi caotici di conoide alluvionale. la morfologia dell’alta val d’agri è alquanto differenziata: infatti, mentre lungo il tratto più elevato del suo corso il fiume agri scorre all’interno di un fondo vallivo piatto e alluvionato, a cominciare dagli abitati di villa d’agri e tramutola i versanti della valle cominciano ad essere reincisi e terrazzati dal fiume e dai suoi affluenti. sui versanti del settore centro-orientale dell’alta val d’agri sono stati rilevati quattro ordini di superfici terrazzate (i, ii-a, iii-a e iv-a), sia erosionali che deposizionali, impostate sia sul substrato pre-quaternario che sul tetto dei depositi clastici quaternari del complesso val d’agri (fig. 2). alcuni relitti della superficie più antica (terrazzo iva), costituita da una spianata d’erosione impostata prevalentemente sui depositi terrigeni miocenici del flysch di gorgoglione, sono ubicati su ambedue i versanti vallivi tra montemurro e il torrente armento, ad una quota compresa tra 780 e 850 m circa. questa superficie è stata attribuita al pleistocene medio (di niro et al., 1992) sulla base di una correlazione fisica con una superficie sviluppata a quote analoghe al tetto delle 'sabbie e conglomerati di serra corneta', affioranti a est dell’armento, nel bacino di sant’arcangelo, e attribuite al pleistocene medio (pieri et al., 1994; casciello et al., 2000). se questa interpretazione è corretta, il pleistocene medio rappresenta, probabilmente nella sua parte inferiore, il limite cronologico inferiore dell’intera successione terrazzata dell’alta val d’agri. il terrazzo iii-a è rappresentato da una superficie ampia e piuttosto continua, riconoscibile sui due versanti dell’agri compresi tra villa d’agri e montemurro ed estesa nella fascia altimetrica compresa tra 560 m e 700 m circa. probabilmente, lungo il versante sinistro della valle la superficie di ordine iii-a è presente anche a quote più elevate, ricoperta da alcuni conoidi alluvionali. la superficie di ordine iii-a è dissecata trasversalmente dai numerosi torrenti che affluiscono nell’asta fluviale principale e che incidono profondamente i sedimenti fluvio-lacustri del complesso val d’agri. una caratteristica peculiare di questo ordine terrazzato è la sua notevole ampiezza, intesa come distanza tra bordo interno e bordo esterno, che varia da un minimo di 3 km circa fino a raggiungere un massimo di 5 km circa sul versante destro dell’agri, ad est di grumento nova. la superficie terrazzata è impostata quasi interamente sul top dei depositi fluvio-lacustri quaternari del complesso val d’agri, per cui la sua età risulta compresa tra l’età del terrazzo iv-a (pleistocene medio basale) e l’età del tetto del complesso val d’agri (pleistocene superiore). la successione terrazzata dell’alta val d’agri termina con due ordini di terrazzi fluviali (terrazzi ii-a e i), anch’essi impostati sui depositi quaternari della valle e rappresentati da due superfici molto meno ampie del terrazzo iii-a, che si estendono tra grumento nova e spinoso sia parallelamente al corso dell’agri, sia lungo alcuni tributari di destra, come il torrente maglia (fig. 2). il bordo interno del terrazzo ii-a si trova ad una quota di circa 550 m, mentre il bordo esterno viene stagionalmente sommerso dalle acque del lago artificiale del pertusillo, il cui livello è stato fissato a circa 530 m sulla base cartografica a scala 1:50.000 utilizzata per questo lavoro. poiché l’analisi aereofotogrammetrica è stata eseguita su stereocoppie scattate in un periodo precedente alla costruzione della diga del pertusillo, è stato possibile individuare anche l’ordine terrazzato più recente (terrazzo i), di solito completamente sommerso dalle acque dell’invaso e quindi non cartografabile attualmente, delimitato a monte da un bordo interno localizzato ad una quota media di circa 520 m. la mancanza di riferimenti cronologici assoluti all’interno della successione di terrazzi fluviali del settore a della val d’agri, non consente di elaborare una precisa interpretazione quantitativa dell’evoluzione morfotettonica di questo settore. tuttavia, la distribuzione e le caratteristiche morfologiche delle superfici terrazzate, assieme all’analisi stratigrafica dei depositi clastici quaternari che riempiono il bacino dell’alta val d’agri, indicano che questo settore ha subito un’evoluzione morfologica e sedimentaria controllata prevalentemente dallo sviluppo della soglia in corrispondenza dell’anticlinale con asse nno-sse associata al sovrascorrimento dell’armento. anche un possibile effetto di morfoselezione ha certamente influito sull'evoluzione di questo tratto del fiume, dove si può tuttora notare (fig. 3) l’esistenza di un knick-point lungo il profilo del fondo valle. e’ 162 m. bianca & r. caputo 163 comunque evidente che, poiché la forra formatasi attraverso l’anticlinale dell’armento incide un’unica litologia (flysch di gorgoglione), quest’ultimo effetto non può da solo giustificare la presenza di terrazzi fluviali. l’attribuzione della superficie di spianamento di ordine iv-a al pleistocene medio (di niro et al., 1992) pone un limite ante quem all’intera successione terrazzata di questo settore. nell’intervallo di pleistocene medio compreso tra la formazione della superficie di ordine iv-a e il terrazzo di ordine iii-a, si è verificato l’episodio di parziale riempimento del settore dell'alta val d'agri che ha portato alla deposizione delle argille lacustri basali del complesso val d’agri (di niro et al., 1992). e’ possibile ipotizzare che questo episodio deposizionale sia collegato con una fase di forte innalzamento relativo della soglia, durante la quale il fiume agri fig. 3 proiezione longitudinale dei bordi interni dei terrazzi fluviali e marini presenti rispettivamente sui versanti della val d’agri e lungo il tratto costiero ionico adiacente alla foce del fiume. sono inoltre schematizzati i principali elementi strutturali che intersecano la valle. si notino la brusca variazione di pendenza (knick-point) lungo il profilo del terrazzo fluviale di ordine i in corrispondenza dell’anticlinale dell’armento (settore a), i terrazzi fluviali deformati in riva destra della media val d’agri (settore b) e la corrispondenza morfologica tra terrazzi fluviali e marini dello stesso ordine nell’ultimo tratto fluviale (settore c). legenda: 1 = asse di anticlinale; 2 = faglia; 3 = traccia longitudinale di bordo interno di terrazzo fluviale; 4 = traccia di bordo interno di terrazzo marino, e relativo ordine. longitudinal projection of the inner edges of the fluvial and marine terraces occurring on the flanks of the agri valley and along the ionian coastal reach of the river mouth. main structural features are also sketched. it is worthy to note the knick-point in the profile of the fluvial terrace i, corresponding to the armento anticline (sector a), the warped fluvial terraces along the right flank of the middle agri valley (sector b) and the morphological continuity of the fluvial and marine terraces of the same order along the last fluvial reach (sector c). legend: 1 = axis of anticline; 2 = fault; 3 = longitudinal trace of the inner edge of fluvial terrace; 4 = trace of inner edge of marine terrace and relative order. analisi morfotettonica ... continua comunque ad incidere un profondo canyon perpendicolarmente alla zona di cerniera dell’anticlinale, ma con una velocità inferiore a quella del sollevamento tettonico della soglia. si è così formato l'attuale profilo a geometria articolata. alla fine del pleistocene superiore, il tasso di sollevamento relativo della soglia diminuisce fino ad essere superato dal tasso di incisione verticale dell’agri, con il conseguente svuotamento graduale del 'paleolago' del pertusillo. il risultato morfologico di questo processo è rappresentato dall’ampia superficie del terrazzo iii-a impostata sul tetto del complesso val d’agri. la continuità del fenomeno, testimoniata dalla particolare ampiezza e regolarità morfologica della superficie del terrazzo iii-a, conferma l’avvenuto arresto del processo di sollevamento tettonico dell’area di soglia e la persistenza di un 'effetto filtro' generato dalla soglia stessa che ha annullato l'influenza delle oscillazioni eustatiche sull’evoluzione morfologica dei versanti sia del lago che del canyon in incisione. in questa ipotesi di modello morfo-evolutivo indipendente dalle oscillazioni eustatiche, i due ordini di terrazzi fluviali più recenti ii-a e i possono essere interpretati come il risultato di altrettante fasi di sollevamento locale che sono state tentativamente attribuite all'attività recente di una o più strutture bordiere dell'alta val d'agri (fig. 2; burrato, 1995). inoltre, anche le variazioni climatiche potrebbero aver giocato un ruolo nella formazione dei terrazzi fluviali. non conoscendo, però, l’età precisa di questi ultimi, non è possibile quantificare il contributo climatico nell’intero processo evolutivo. settore b: media val d’agri questo settore di valle è compreso tra l’armento e un’altra importante soglia di origine tettonica rappresentata dalla faglia di scorciabuoi (lentini & vezzani, 1974), una struttura lunga circa 40 km e caratterizzata da un andamento curvilineo, con direzione variabile da ono-ese a no-se (fig. 4). l’attività di questa faglia, che sembra essere iniziata nel pleistocene medio (pieri et al., 1997), è stata caratterizzata da una cinematica inizialmente di tipo traspressivo sinistro, in quanto tale struttura ha probabilmente agito come rampa lateraleobliqua del sovrascorrimento che ha prodotto l'anticlinale di rotondella (fig. 1). successivamente, nell'attuale regime tettonico estensionale che caratterizza l'asse della catena appenninica, la faglia di scorciabuoi è stata invertita acquisendo così una cinematica trastensiva destra (casciello, 2002). il tratto centrale della val d’agri scorre sulle successioni sedimentarie del bacino di sant’arcangelo, interpretato come thrust-top basin formatosi nel pliocene superiore sui sovrascorrimenti più esterni dell’appennino lucano ed evolutosi a bacino di piggyback nel pleistocene inferiore-medio (pieri et al., 1994; casciello, 1999). questo bacino è prevalentemente caratterizzato da tre sequenze deposizionali marine, d'età compresa tra il pliocene superiore e il pleistocene 164 fig. 4 carta morfotettonica della media val d’agri (settore b). legenda: 1 = substrato dei terrazzi fluviali quaternari; 2 = terrazzo fluviale i; 3 = terrazzo fluviale ii-b; 4 = terrazzo fluviale iii-b; 5 = terrazzo fluviale iv-b; 6 = superficie terrazzata v-b; 7 = immersione delle superfici terrazzate; 8 = traccia delle sezioni trasversali rappresentate in figura 5. morphotectonic map of the middle agri valley (sector b). legend: 1 =? substratum of the quaternary fluvial terraces; 2 = fluvial terrace i; 3 = fluvial terrace ii-b; 4 = fluvial terrace iii-b; 5 = fluvial terrace iv-b; 6 = terraced surface v-b; 7 = dip of the terraced surfaces; 8 = trace of the crosssections represented in figure 5. m. bianca & r. caputo inferiore, ricoperte da una sequenza sedimentaria continentale del pleistocene medio, denominata formazione di serra corneta (pieri et al., 1994). gli elementi morfologici fluviali presenti lungo questo secondo settore si sono quindi sviluppati in un intervallo compreso tra la parte alta del pleistocene medio e l’olocene. in corrispondenza del bordo orientale del bacino di sant’arcangelo, la faglia di scorciabuoi mette in contatto laterale i depositi clastici plio-pleistocenici precedentemente descritti con i terreni bacinali meso-cenozoici e i depositi silicoclastici miocenici delle unità sicilidi, strutturalmente localizzati in corrispondenza della dorsale di rotondella (pieri et al., 1997). la funzione di 'soglia' della faglia di scorciabuoi rispetto all’attività erosiva dell’agri è probabilmente legata alla presenza di litotipi caratterizzati da un grado di erodibilità sensibilmente diverso, in quanto i terreni sicilidi sono generalmente meno erodibili dei depositi clastici del bacino di sant’arcangelo. lungo la media val d’agri sono stati riconosciuti tre ordini di terrazzi fluviali più alti del terrazzo i, che mostrano una distribuzione notevolmente asimmetrica sviluppata prevalentemente lungo la riva destra dell’agri (fig. 4). la successione terrazzata è ottimamente esposta in corrispondenza di una fascia lunga circa 12 km in prossimità dell’abitato di sant’arcangelo (riva destra), mentre in riva sinistra la serie di terrazzi è visibile solo per una distanza di alcune centinaia di metri a se dell’abitato di missanello. il profilo longitudinale dei bordi interni delle superfici terrazzate (fig. 3) evidenzia un piegamento antiforme dei terrazzi fluviali, compreso l’ultimo terrazzo alluvionale (terrazzo i). sebbene non sia possibile determinare la direzione e l’immersione dell’asse di questa anticlinale, è probabile che il suo orientamento sia analogo all’andamento assiale del sistema di strutture plicative sviluppato sui depositi marini e continentali del bacino di sant’arcangelo (fig. 4). questa analogia strutturale suggerisce che i terrazzi fluviali possano essere stati sollevati e piegati a causa dell’attività tardo pleistocenica di una faglia inversa minore sepolta e parallela alle principali strutture superficiali presenti nel settore della media val d’agri (fig. 4). inoltre, è da notare che, in corrispondenza della sezione 1 (fig. 5) tracciata a circa 3 km ad ovest di sant’arcangelo, i terrazzi fluviali occupano una fascia altimetrica compresa tra 420 m (terrazzo iv-b) e 240 m circa. le sezioni 1 e 2 (fig. 5), tracciate a poche centinaia di metri l’una dall’altra, mostrano la netta asimmetria della distribuzione dei terrazzi fluviali presenti, in questo settore, solo sul versante destro del fiume. risulta quindi evidente, in questo tratto del fiume, uno spostamento verso nord dell'attuale letto. e' probabile che gli apporti sedimentari progressivamente scaricati nell’agri dal suo affluente di destra fiumarella di roccanova abbiano causato tale migrazione dell’asta fluviale principale, favorendo così l'erosione dei terrazzi fluviali che presumibilmente si erano formati anche sul versante settentrionale. in alternativa a tale ipotesi, legata alle normali dinamiche fluviali erosivo-deposizionali, è però verosimile imputare tali variazioni altimetriche (longitudinale e trasversale) a fenomeni deformativi recenti associati alle strutture plicative presenti in questo settore del bacino di sant'arcangelo (fig. 4). le osservazioni eseguite in corrispondenza del tratto vallivo intersecato dalla faglia di scorciabuoi hanno fornito le seguenti indicazioni sull’attività di questa struttura. il profilo longitudinale del letto fluviale attuale (fig. 3) mostra una leggera variazione di pendenza in corrispondenza dell’intersezione con la faglia di scorciabuoi, non permettendo però di separare l'effetto dovuto alla tettonica da quello legato alle diverse litologie incise dal fiume. l'evidente deviazione quasi ad angolo retto del corso dell’agri, che a pochi km a sud della faglia passa da una direzione circa e-w ad una direzione circa nne-sso, sembra invece geometricamente compatibile con una dislocazione cumulativa chilometrica associata alla cinematica trascorrente sinistra, già ipotizzata per questa struttura (casciello, 2002). dall'analisi della morfologia del fiume, comunque, non si hanno elementi per riconoscere l'evidenza di una attività tettonica recente di questa faglia che è stata ipotizzata come struttura sismogenica, potenzialmente associata all'evento sismico della basilicata del 1857 (lizza, 2001). settore c: bassa val d’agri il settore più basso della val d’agri è caratterizzato non solo dalla presenza di tre ordini di terrazzi fluviali ben definiti, ma anche da una sequenza di sei terrazzi marini che si estendono lungo il tratto costiero ionico adiacente alla foce del fiume (fig. 6a). analogamente ai terrazzi fluviali, anche quelli marini vengono indicati con cifre romane crescenti procedendo dall’ordine più 165 fig. 5 sezioni trasversali del fiume agri, eseguite a ovest dell’abitato di sant’arcangelo (ubicazione in figura 4). si noti l’asimmetria dei terrazzi fluviali ii-b, iii-b e iv-b, presenti solo sul fianco meridionale della valle (sezione 1), e la migrazione del fiume verso nord in concomitanza con il sollevamento del terrazzo i (sezione 2). cross-sections of the agri valley, traced west to the sant’arcangelo village (for location, see fig. 4). the asymmetry of terraces ii-b, iii-b and iv-b, occurring only along the southern flank of the valley (section 1), and the northward migration of the agri river in the area where the terrace i is uplifted (section 2) are observed. analisi morfotettonica ... basso e recente verso quello più alto e più antico. dal punto di vista sedimentario, i terrazzi costieri sono costituiti da depositi marini conglomeratico-sabbiosi caratterizzati dalla classica geometria cuneiforme legata all’aumento di spessore che si osserva procedendo dal bordo interno al bordo esterno di ogni singolo terrazzo. questi corpi sedimentari terrazzati poggiano in discordanza sulle argille marnose grigio-azzurre dell’avanfossa bradanica (fig. 1), il cui tetto stratigrafico è attribuito al pleistocene inferiore (carbone et al., 1991). i cinque ordini di terrazzi più bassi (fig. 6b) sono 166 fig. 6 a) carta morfotettonica della bassa val d’agri (settore c). legenda: 1 = substrato dei terrazzi fluviali e marini quaternari; 2 = terrazzo fluviale i e terrazzo marino i-m; 3 = terrazzo fluviale ii-c e terrazzo marino ii-m; 4 = terrazzo fluviale iii-c e terrazzo marino iii-m; 5 = terrazzo marino iv-m; 6 = terrazzo marino v-m; 7 = terrazzo marino di ordine vi-m; 8 = bordo interno di terrazzo marino e/o fluviale con relativa quota in metri s.l.m. b) panoramica da s della serie di terrazzi marini dell’area di montalbano, localizzati lungo il versante sinistro della bassa val d’agri (settore c) e poggianti in discordanza sulle argille azzurre plio-pleistoceniche dell’avanfossa bradanica. in primo piano, il terrazzo fluviale i. il terrazzo marino più basso (i-m) non è visibile. a) morphotectonic map of the low agri valley (sector c). legend: 1 = substratum of the quaternary fluvial and marine terraces; 2 = fluvial terrace i and marine terrace i-m; 3 = fluvial terrace ii-c and marine terrace ii-m; 4 = fluvial terrace iii-c and marine terrace iii-m; 5 = marine terrace iv-m; 6 = marine terrace v-m; 7 = marine terrace vi-m; 8 = inner edge of fluvial and/or marine terrace and its elevation in m a.s.l b) view from s to n of the sequence of marine terraces of the montalbano area, developed along the left flank of the agri valley and overlying the plio-pleistocene clays of the bradanic foredeep. in the foreground, the fluvial terrace i. the lowest marine terrace i-m is not visible. m. bianca & r. caputo delimitati verso monte dalle loro rispettive paleolinee di costa, mentre il terrazzo più alto, sul quale è stata costruita la parte più antica dell’abitato di montalbano, è rappresentato da una superficie isolata che verso l’entroterra si interrompe bruscamente in corrispondenza di un versante calanchivo inciso sulle sottostanti argille azzurre. i tre ordini di terrazzi fluviali presenti su ambedue le rive del fiume (iii-c, ii-c e i), mostrano una chiara continuità fisica con i terrazzi iii-m, ii-m e i-m, rispettivamente. infatti, è facile osservare come ogni coppia di terrazzo fluviale e terrazzo marino correlati sia delimitata a monte dallo stesso bordo interno che, in prossimità della costa, curva ad angolo retto, passando da un’orientazione perpendicolare alla costa ad un’orientazione parallela ad essa. questo tipo di correlazione morfologica è sufficiente per confermare che i tratti di scarpata paralleli alla linea di costa attuale sono sicuramente interpretabili come bordi interni di terrazzi marini, escludendo la possibilità che si tratti di eventuali scarpate di faglie dirette che dislocano verticalmente un singolo terrazzo marino. inoltre, il segnale eustatico assieme al sollevamento tettonico rappresentano evidentemente i fattori morfogenici più importante anche per la formazione dei terrazzi fluviali presenti lungo il tratto finale del fiume agri. per quanto riguarda i terrazzi marini che sono presenti in prossimità della foce dell’agri, si è utilizzato un modello di deformazione basato sull’assunzione generale secondo cui una successione marina terrazzata pleistocenica rappresenta il risultato geomorfologico più evidente dell’interazione tra il sollevamento tettonico di un’area costiera e le oscillazioni glacio-eustatiche globali del livello marino (selli, 1962; lajoie, 1986; westaway, 1993; bosi et al., 1996; armijo et al., 1996; bianca et al., 1999). le oscillazioni glacio-eustatiche quaternarie sono state oggetto di numerosi studi precedenti (chappell, 1974; ward, 1985; chappell & shackleton, 1986; aharon & chappell, 1986; shackleton, 1987; chappell et al., 1996), che hanno consentito l’elaborazione di un modello di curva eustatica (fig. 8), riferita agli ultimi 400 ka e che può essere ormai considerata sufficientemente affidabile e valida a scala globale. la curva eustatica evidenzia come il livello marino abbia subito oscillazioni assolute di circa 120-130 m, tra le fasi glaciali di basso eustatico (picchi 'freddi', indicati con le cifre pari) e le fasi interglaciali di alto eustatico (picchi 'caldi', indicati con le cifre dispari). inoltre, è importante osservare che negli ultimi 400 ka il mare ha superato il livello attuale soltanto durante lo stadio interglaciale 5.5 (125 ka), detto eutirreniano (+6 m; chappell & shackleton, 1986). un singolo terrazzo marino è costituito da un insieme più o meno complesso di elementi erosivi e deposizionali (bordi interno ed esterno, superficie superiore, deposito marino, ecc.) formatosi durante una fase di stazionamento relativo del livello marino rispetto alla terraferma. verso monte, il terrazzo marino è delimitato del bordo interno, che corrisponde alla paleolinea di costa relativa al livello massimo raggiunto dal mare durante la relativa fase di alto stazionamento eustatico (bloom et al., 1974; ota, 1994; bosi et al., 1996). lungo un’ipotetica fascia costiera non soggetta a movimenti tettonici verticali, sarebbe quindi possibile osservare un unico terrazzo marino con la relativa paleolinea di costa, assieme al suo corrispondente terrazzo fluvio-alluvionale lungo l’ultimo tratto degli eventuali corsi d’acqua presenti, tutti correlati allo stadio oit 5.5 (eutirreniano, 125 ka), mentre le eventuali tracce di stazionamento marino degli altri stadi interglaciali sarebbero attualmente sommerse. una paleolinea di costa rappresenta quindi un elemento morfologico, originariamente orizzontale, formatosi ad una quota assoluta deducibile, in seguito ad una sua datazione diretta o indiretta, dalla curva eustatica di riferimento. la quota attuale (qf) di una paleolinea di costa è funzione della sua età, della quota iniziale (qi) alla quale si è formata e della velocità del sollevamento tettonico (st), secondo la formula: qf = (età x st) + qi dalla quale si può ricavare il sollevamento tettonico st= (qf qi) / età. di conseguenza, le quote assolute di una serie di paleolinee di costa datate, misurate lungo sezioni trasversali, consentono di ottenere dei diagrammi di velocità di sollevamento che quantificano la storia deformativa dell’area costiera in esame. e’ importante rilevare che un tasso di sollevamento medio di 0,2-0,3 mm/a è sufficiente per consentire la 'fossilizzazione' dell’intera successione di terrazzi marini relativi ai principali picchi interglaciali della curva eustatica (bianca, 1998), a partire dal terrazzo di età corrispondente all’inizio del processo di sollevamento. tuttavia, perché ciò si verifichi è necessario che il processo di sollevamento sia continuo per un intervallo di tempo dell’ordine di 104-105 anni, corrispondente al periodo delle principali oscillazioni eustatiche (fig. 7a). questo modello di morfogenesi assume una particolare importanza nello studio dei settori costieri terrazzati in cui le evidenze geomorfologiche, possibilmente integrate con almeno un vincolo cronologico assoluto, confermano la persistenza di un processo di sollevamento tettonico quaternario continuo e sufficientemente veloce, in quanto consente la datazione indiretta dell’intera successione di terrazzi marini. gli studi precedenti sulla distribuzione dei terrazzi marini presenti lungo il settore costiero dell’avanfossa bradanica sono concordi nell’attribuire l’intera successione terrazzata al pleistocene medio-superiore (de marco, 1990; amato et al., 1997). la presenza stessa di sei ordini di terrazzi marini medio-suprapleistocenici rappresenta l’evidenza geomorfologica più convincente del fatto che questo settore costiero è stato interessato da un sollevamento tettonico sufficientemente rapido da consentire la registrazione morfologica di una serie continua di alti stazionamenti marini corrispondenti ad alcuni dei principali picchi interglaciali della curva eustatica globale (fig. 7a). sebbene nessuno dei terrazzi marini analizzati in questo lavoro sia stato datato, alcune datazioni assolute sono state eseguite su alcuni terrazzi presenti immediatamente a sud della foce dell’agri. in particolare, nei pressi di rocca imperiale, un terrazzo posto a circa 100 m di quota è stato attribuito allo stadio isotopico 5.3 tendente al 5.5 (fig. 7a), che corrisponde ad un’età compresa tra 100 e 125 ka (amato et al., 1997). poiché la nostra interpretazione del numero di terrazzi marini non concorda con quella di amato et al. (1997), non è possibile correlare il terrazzo datato con uno dei terrazzi analizzati nel presente lavoro. tuttavia, questa datazione costituisce un importante vincolo per l’interpretazione cronologica della successione terrazzata presente lungo il tratto costiero della foce dell’agri. 167analisi morfotettonica ... sulla base del modello morfogenico precedentemente discusso e delle datazioni disponibili in aree limitrofe, abbiamo utilizzato le quote delle cinque paleolinee di costa più recenti, misurate lungo la sezione 3 (fig. 6a), proponendo così quattro ipotetici modelli quantitativi di deformazione verticale (figg. 7b-e). questi modelli sono stati ottenuti ipotizzando quattro diverse età per il terrazzo v-m, corrispondenti rispettivamente agli stadi interglaciali oit 11.1 (410 ka), 9.3 (330 ka), 7.5 (240 ka) e 7.1 (200 ka) della curva eustatica (fig. 7a), attribuendo così ai terrazzi più recenti le età dei picchi interglaciali successivi. i diagrammi così ottenuti descrivono quattro diverse ipotesi di evoluzione morfotettonica del settore costiero della val d’agri, con tassi di sollevamento medi decrescenti all’aumentare dell’età ipotetica del terrazzo v-m (fig. 7b). i relativi diagrammi (figg. 7b, 7c and 7d) mostrano tassi di sollevamento notevolmente variabili durante gli ultimi 200-300 ka, compresi tra circa 0,2 mm/a (fig. 7d) e 2,8 mm/a (fig. 7b). il diagramma rappresentato in figura 7e, ottenuto ipotizzando un’età di 410 ka (oit 11.1) per il terrazzo v-m, indica un tasso di sollevamento più costante, compreso tra 1,1 e 0,8 mm/a fino a 125 ka (oit 5.5), che si riduce quasi a zero da 125 ka ad oggi. nei diagrammi sono anche indicati i tassi medi di sollevamento, che ovviamente decrescono con l'aumentare dell'età ipotetica del terrazzo v-m, variando da 1,35 mm/a a 0,64 mm/a. un altro dato importante sulla deformazione tettonica medio-suprapleistocenica del settore costiero della val d’agri è stato ottenuto dell’analisi della proiezione longitudinale dei cinque ordini di paleolinee di costa (fig. 8) lungo una direzione nne-sso (sezione 4 in fig. 6a), cioè parallela alla linea di riva attuale. la proiezione mostra un basculamento evidente di tutte le paleolinee di costa dall'ordine v-m al ii-m, che, formatesi con una geometria originariamente orizzontale, mostrano attualmente un’inclinazione verso ne. la paleolinea di ordine i-m, al contrario, mostra ancora un andamento suborizzontale. questo tipo di deformazione indica chiaramente un sollevamento tettonico differenziale del settore costiero ionico, verificatosi durante il periodo compreso tra la formazione delle paleolinee v-m e i-m, la cui entità decresce gradualmente verso ne, ovvero verso il fronte di sovrascorrimento più esterno dell’appennino meridionale (figg. 1 e 6a). ccoonnssiiddeerraazziioonnii ccoonncclluussiivvee la presenza di diversi ordini di superfici terrazzate lungo l’intero corso dell’agri, assieme ad una successione di terrazzi marini localizzati in prossimità della foce, tutti riferibili al quaternario, indicano un processo di 168 fig. 7 -a) curva eustatica globale (modificata da shackleton, 1987). i numeri indicano le fasi principali di alto stazionamento del livello marino, corrispondenti agli stadi interglaciali più importanti. – b-e) diagrammi raffiguranti il processo di sollevamento tettonico del settore costiero della val d’agri, basato sulle quote attuali delle paleolinee di costa dall'ordine i-m al v-m, misurate lungo la sezione 3 (fig. 6a). i tassi di sollevamento sono stati calcolati per intervalli compresi tra due paleolinee successive, attribuendo alla paleolinea di ordine v-m quattro diverse possibili età comprese tra 200 e 410 ka. a) global eustatic curve (modified from shackleton, 1987). the numbered peaks represent the marine high-stands corresponding to the main interglacial stages. b-e) diagrams showing the tectonic uplift of the coastal area of the agri valley, based on the present elevation of the palaeoshorelines of order i-m to v-m measured along section 3 (fig. 6a). uplift rates have been calculated for time spans between two consecutive palaeo-shorelines, assuming four different ages for the marine terrace v-m in the interval 200-410 ka. fig. 8 proiezione longitudinale delle paleolinee di costa (tratteggiate quando interpolate) di ordine compreso tra i-m e v-m lungo una direzione parallela alla costa attuale, orientata nnesso (traccia 4 in fig. 6a). il diagramma mostra un evidente basculamento delle paleolinee, originariamente orizzontali, la cui quota decresce verso nne. longitudinal projection of the palaeo-shorelines (dashed where inferred) of order i-m to v-m along a nne-ssw-striking direction, parallel to the present coastline (trace 4 in fig. 6a). a tilting of the coastal area, indicated by north-northeastward decreasing elevations of the palaeo-shorelines, can be observed. m. bianca & r. caputo approfondimento continuo e articolato di questa valle che si è protratto, con l’eccezione del tratto iniziale dell’alta val d’agri, fino all’olocene. il continuo abbassamento del livello di base dell’erosione dell’agri rappresenta la conseguenza più evidente del processo di sollevamento tettonico che ha interessato questo settore di appennino lucano e di avanfossa bradanica durante il quaternario (fig. 1). l’entità dei movimenti verticali positivi deve essere considerata come la risultante del sollevamento tettonico regionale, tipicamente diffuso e generalmente uniforme alle scale ridotte, e della componente di sollevamento localmente legata all’attività di possibili strutture neotettoniche. i risultati di questo studio morfotettonico hanno consentito di elaborare alcuni modelli qualitativi e quantitativi di evoluzione tettonica quaternaria della val d’agri, con la conseguente individuazione di alcuni settori dove le deformazioni recenti sono probabilmente legate alla presenza di strutture recenti o attive. due importanti soglie morfostrutturali, il sovrascorrimento dell’armento e la faglia di scorciabuoi (fig.1), intersecano ad alto angolo il corso dell’agri, suddividendo la valle in tre settori caratterizzati da una evoluzione morfologica quaternaria differenziata. in alta val d’agri, i processi erosivi e deposizionali sembrano regolati principalmente dalle fasi più recenti di sollevamento relativo della soglia posta in corrispondenza dell’anticlinale dell’armento. l’ultima fase di sollevamento di questa soglia, infatti, ha permesso la formazione del 'paleolago' del pertusillo e l’inizio della sedimentazione del complesso val d’agri durante il pleistocene medio-superiore. l'incisione della soglia da parte del fiume agri per erosione regressiva indotta dal sollevamento regionale causa il progressivo svuotamento del lago e l'incisione parziale degli stessi depositi fluviolacustri del complesso val d’agri. i terrazzi fluviali più recenti, probabilmente olocenici, rappresentano il risultato morfologico di fasi di sollevamento episodiche che riteniamo indipendenti dalle oscillazioni eustatiche del livello marino, e che potrebbero quindi essere collegate all’attività recente di una o più strutture bordiere dell’alta val d’agri e, in misura minore, ad effetti climatici. in media val d’agri, i terrazzi fluviali medio-suprapleistocenici e olocenici evidenziano una geometria antiforme che sembra strutturalmente compatibile con le principali strutture fragili e plicative che deformano i terreni plio-pleistocenici del bacino di sant’arcangelo. e’ quindi ipotizzabile che il regime tettonico compressivo orientato circa ne-so sia perdurato fino all’olocene. la possibile presenza di una o più strutture sismogeniche nella media val d’agri (lizza, 2001) potrebbe inoltre spiegare la forte intensità macrosismica (i=x mcs) registrata dai centri abitati di aliano e alianello durante il terremoto della basilicata del 1857 (m=6.5; boschi et al., 1995). infine, in bassa val d’agri, la buona correlazione geometrica tra terrazzi fluviali e marini sottolinea il ruolo determinante delle variazioni eustatiche nei processi morfogenici che hanno modellato questo settore di valle. in base all’ipotesi che la successione terrazzata del pleistocene medio-superiore rappresenti una serie continua di elementi morfologici correlati con alcune delle principali fasi interglaciali indicate dalla curva eustatica di riferimento, sono state elaborate quattro ipotesi alternative che quantificano i tassi di sollevamento del settore costiero della foce dell’agri. la notevole variabilità dei tassi di sollevamento, gli alti valori dei tassi più elevati (~3 mm/a) e l’evidente basculamento delle paleolinee di costa, suggeriscono che il sollevamento di quest’area sia da associare all’attività recente di una o più strutture tettoniche presenti in questo settore esterno di catena appenninica, e non soltanto al sollevamento regionale, che viene normalmente considerato più costante, omogeneo e caratterizzato da velocità meno elevate. rriinnggrraazziiaammeennttii si ringraziano 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183-190. vandenberghe j., 2002 – the relation between climate and river processes, landforms and deposits during the quaternary. quaternary international, 9911, 17-23. ward w. t., 1985 – correlation of east australian pleistocene shorelines with deep-sea cores stages: a basis for a coastal chronology. geol. soc. am. bull., 96, 99, 1156-1166. westaway r., 1993 – quaternary uplift of southern italy. j. geophys. res., 9988, 21741-21772. 170 ms. ricevuto il 7 gennaio 2003 testo definitivo ricevuto il 24 giugno 2003 ms. received: january 7, 2003 final text received: june 24, 2003 m. bianca & r. caputo imp.perilli& villafranchian deposits of the barga and castelnuovo garfagnana basins (tuscany, italy): lithostratigraphy and sedimentary features nicola perilli, alberto puccinelli, giovanni sarti & giacomo d’amato avanzi dipartimento di scienze della terra, università di pisa. via s. maria 53 – 56126 pisa – italy sarti@dst.unipi.it perilli@dst.unipi.it abstract: n. perilli et al., villafranchian deposits of the barga and castelnuovo garfagnana basins (tuscany, italy): lithostratigraphy and sedimentary features. (it issn 0394-3356, 2004). based on a refined mapping of the sedimentary wedges accumulated in the so-called barga and castelnuovo garfagnana basins and on a review of previous studies, the distinguished formations are here described. the “argille, sabbie e conglomerati di fornaci di barga” mainly consists of fine grained lithofacies with organic-rich horizons and coarse grained conglomerate. the “conglomerati di barga”, dominated by coarse grained lithofacies, is also characterized by silty to sandy interbeds, whilst organic-rich levels and paleosol horizons are rare. within this formation, the mt. alfonso member is also distinguished, albeit hardly mappable. sedimented in two separated tectonic depressions, connected by the “mt. perpoli high”, this succession has been interpreted in previous studies as ranging from cohesive sediment anabranching (“argille, sabbie e conglomerati di fornaci di barga”) to gravel bed-load braided river deposits (“conglomerati di barga”), roughly flowing from north to south. in the castelnuovo garfagnana area, the mt. alfonso member also records the development of a tributary river flowing from west to east and interpreted as a braided fluvial fan. in this frame, the “mt. perpoli high” acted as a sedimentary by-pass, since the beginning of the sedimentation. riassunto: n. perilli et al., i depositi villafranchiani dei bacini di barga e castelnuovo garfagnana (toscana, italia): litostratigrafia e caratteristiche sedimentarie. (it issn 0394-3356, 2004). sulla base di rilevamenti geologici di dettaglio effettuati nei depositi villafranchiani dei bacini di barga e castelnuovo garfagnana e di una revisione della letteratura, vengono definite le caratteristiche litostratigrafiche delle due formazioni riconosciute. la formazione delle “argille, sabbie e conglomerati di fornaci di barga” giace in discordanza sul substrato costituito da unità toscane metamorfiche (nucleo metamorfico apuano) e non metamorfiche (falda toscana) e, subordinatamente, da unità liguri e subliguri (unità ottone e unità canetolo); essa è caratterizzata prevalentemente da litofacies fini, con livelli di accumulo organico e di orizzonti pedogenetici e intercalazioni di conglomerati. la formazione dei “conglomerati di barga” è invece costituita da litofacies conglomeratiche, con sporadiche intercalazioni siltoso-sabbiose, a cui talvolta si associano paleosuoli e rari livelli di accumulo organico. all’interno di questa formazione, è stato distinto nell’area di castelnuovo garfagnana il membro di m. alfonso, costituito da conglomerati grossolani eterometrici. la formazione dei “conglomerati di barga” giace in possibile discordanza sulle “argille, sabbie e conglomerati di fornaci di barga”, anche se le cattive condizioni di affioramento non permettono di escludere a priori un possibile passaggio stratigrafico. le due formazioni vengono attribuite a due sistemi fluviali riferibili rispettivamente a un cohesive sediment anabranching river (“argille, sabbie e conglomerati di fornaci di barga”) e a un gravel bed-load braided river (“conglomerati di barga”), ambedue ad andamento circa nord–sud. il membro di m. alfonso registrerebbe invece la deposizione, nel bacino di castelnuovo garfagnana, di un sistema tributario attribuibile ad un braided fluvial fan a decorso circa ovest-est e alimentato dalle alpi apuane. in questo quadro, la soglia di monte perpoli avrebbe agito come by-pass sedimentario fin dall’inizio della deposizione villafranchiana. keywords: lithostratigraphy, continental deposits, villafranchian, tuscany, italy. parole chiave: litostratigrafia, depositi continentali, villafranchiano, toscana, italia. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 313-322 1. introduction since the 19th century, the villafranchian succession cropping out in the barga and castelnuovo garfagnana tectonic depressions (tuscany) was investigated due to its fossil record, mainly represented by vegetable and mammal remains. the paleontological data increased as a consequence of the lignite and clay mining, that ended during the first and last decades of the 20th century, respectively. on the basis of few paleontological studies and limited number of vertebrate remains (de stefani, 1887 and 1889; ugolini, 1902; zaccagna, 1932 and masini, 1936), the villafranchian age of this succession is accepted. the main lithological features of these deposits have been described, among the others, by nardi (1961) and calistri (1974), and mapped at 1:10,000 scale by nardi et al. (1986 and 1987). unfortunately, these papers were not supported by detailed lithostratigraphic and sedimentological studies. nevertheless, based on the significant lignite contents of the fine grained basal sediments and the dominant coarse grained overlying deposits, the whole succession was interpreted as a fluvial-lacustrine cycle. recently, lithostratigraphy and facies analysis of these deposits were investigated by puccinelli et al. (in press, a) and landi et al. (2002-2003), respectively. on the basis of these studies, the main lithostratigraphic and sedimentary features of the villafranchian formations, discontinuously exposed in the barga and castelnuovo garfagnana areas, will be described in this paper. a similar succession, dividable in two formations, crops out north-westward in the aulla-olivola and pontremoli tectonic depressions (bertoldi, 1997 and 314 n. perilli et al. bernini et al., 1990). mainly consisting of fine grained lithofacies with medium to thick coarse grained interbeddings, the “argille, sabbie e conglomerati di aulla” (puccinelli et al., in press, b) is characterized by a variable amount of centimetric to decimetric lignite fragments and organic-rich horizons. it is overlain by the coarse grained “conglomerati di olivola” (puccinelli et al., in press, b), characterized by subordinate fine grained interbeddings. 2. geological setting the investigated area (fig. 1) is one of the continental intermontane tectonic depressions, that opened as a consequence of the counter-clockwise migration of the chain-foredeep-foreland system and of the extension of the northern apenninic tyrrhenian margin (meletti et al., 1995 and references therein) during the late ruscinian/early villafranchian time interval (bernini et al., 1990; bertoldi, 1995 and 1997). roughly comprised between the apuan alps and the apenninic watershed, the studied area includes two tectonic depressions, 5 km wide and 10 (barga) to 15 km (castelnuovo garfagnana) long, separated by the so-called “mt. perpoli high” (soglia di monte perpoli of puccinelli, 1987). these depressions are related to the movement of tectonic blocks collapsed and rotated along antithetical faults and interpreted as half-graben, with the master faults plunging towards the tyrrhenian border (martini & sagri, 1973; eva et al., 1978). the villafranchian succession laid down in the barga and castelnuovo garfagnana depressions unconformably overlies sedimentary successions of the apennine thrustand-fold belt, here represented by the falda toscana (mainly with the macigno formation), canetolo and ottone units. along the western sides of both depressions, the falda toscana in turn tectonically overlies the methamorphic core complex of the apuan alps. 3. previous studies and inferred age the sedimentary succession, cropping out in the barga and castelnuovo garfagnana areas, was investigated entirely by few authors. among them, de stefani (1887 and 1889), zaccagna (1917 and 1932), ugolini (1902), masini (1932 and 1936), tongiorgi & trevisan (1953), azzaroli (1955), nardi (1961) and calistri (1974) focused on stratigraphy, even if only this latter studied the entire villafranchian sedimentary succession. the papers of bartolini & bortolotti (1971), nardi (1961 and 1965), nardi et al. (1986 and 1987), d’amato avanzi & puccinelli (1988), puccinelli (1987), dallan et al. (1991) and moretti (1990) mainly deal with neotectonics and/or landslide hazard. fig. 1 tectonic sketch of the northern apennines and location of the main intermontane tectonic depressions nearby the study area (within the square). schema strutturale dell’appennino settentrionale con la localizzazione delle principali depressioni tettoniche limitrofe all’area di studio (nel riquadro). 315villafranchian deposits of the barga ... 4. lithostratigraphy and sedimentary features of the mapped formations as it is well known, the continental successions cropping out in the intermontane, post-collisional basins are usually badly exposed, due to both the large diffusion of the anthropic activities (e.g. agriculture, urbanization) and vegetation cover. consequently, the vertical and/or lateral outcrop extension is often limited, and the geometric and stratigraphic relationships between formations overshadowed. however, based on some well exposed sections, the entire succession has been rather well reconstructed. in the study areas, most significant sections are located in the barga area, where the mapped formations and the boundary between them are also well exposed. according to previous papers (nardi et al., 1986 and 1987; dallan et al., 1991), in the investigated area two formations have been recognized, and named by puccinelli et al. (in press, a): “argille, sabbie and conglomerati di fornaci di barga” (afb) and “conglomerati di barga” (plb). in the castelnuovo garfagnana area, within plb, the mt. alfonso member is distinguishable. the extension of both formations (afb+plb) is represented in fig. 2. 4.1. argille, sabbie e conglomerati di fornaci di barga (puccinelli et al., in press, a) synonymies argille azzurre lignitifere e sabbie ocracee (nardi, 1961) argille di fornaci di barga pro parte (calistri, 1974) sabbie e argille lignitifere (nardi et al., 1986) argille e sabbie lignitifere (nardi et al., 1987) formazione di fornaci di barga (catanzariti et al., 2002) lithostratigraphic unit 1 (landi et al., 2002-2003) significant outcrops (see tab. 2) barga: rio secco, fornaci di barga, t. loppora, rio zanesi, rio cavo, t. giuvicchia, rio val di lago, le palmente and corsonna. castelnuovo garfagnana: rio la fossa, rio dezza, bamborino, rio valardino, la bottegaccia, villa collemandina, gamberone, antisciana and belvedere. tab. 1 list of vertebrate fossils remains from the “argille, sabbie e conglomerati di fornaci di barga” and “conglomerati di barga” formations. elenco dei resti dei vertebrati fossili provenienti dalle formazioni delle “argille, sabbie e conglomerati di fornaci di barga” e dei “conglomerati di barga”. authors localities fossil remains formations de stefani (1889) barga equus stenonis conglomerati di barga meneghini (1880) ghivizzano tapirus hystrix de stefani (1889) fornaci di barga rhinoceros etruscus rhinoceros etruscus sus arvernensis cervus sp. de stefani (1889) t. loppora felis cfr. isdiorensis meganthereon nestii histrix sp. tapirus sp. mastodon arvernensis ugolini (1902) fornaci di barga tapirus arvernensis cervus pardinensis masini (1936) fornaci di barga mastodon arvernensis emys sp. tapirus sp. la fossa sus sp. felis cfr. isdiorensis cervus sp. mastodon arvernensis de stefani (1887) custia mastodon arvernensis cervus sp. fornaci del ponte mastodon arvernensis castiglione tapirus sp. machiarodus eultridens fornaci del bianchi tapirus sp. sus arvernensis ugolini (1902) t. loppora tapirus arvernensis cervus pardinensis masini (1932) mastodon arvernensis a rg ill e , s a b b ie e c o n g lo m e ra ti d i f o rn a c i d i b a rg a unfortunately, the paleontological data as well as the age-significant fossil remains are scarce (tab. 1). however, the mammal fragments and the presence (landi et al . 2002-2003) of some molluscs (laminifera villafranchiana, prososthenia paulae, theodoxus cf. groyanus) and characean species (nitellopsis cf. megarensis carnevale et al., 2003) point to (according to azzaroli, 1977 and de giuli & masini, 1983) a lower-middle villafranchian age for the “argille, sabbie e conglomerati di fornaci di barga” and allow to assign the overlying “conglomerati di barga” to late villafranchian. 316 fig. 2 schematic geological map of the barga and castelnuovo depressions and nearby areas, based on the geological map at 1:50,000 sheet 250 castelnuovo garfagnana (puccinelli et al., in press, a) and on some geological maps at 1:10,000 scale (nardi et al., 1986 and 1987; dallan et al., 1991). carta geologica schematica dei bacini di castelnuovo garfagnana e barga e delle aree limitrofe, basata sulla carta geologica a scala 1:50.000 – foglio 250 castelnuovo garfagnana (puccinelli et al., in press, a) e su alcune carte geologiche a scala 1:10.000 (nardi et al., 1986 and 1987; dallan et al., 1991). n. perilli et al. 317 afb mainly consists of fine (clayey to sandy) grained lithofacies interbedded by medium to coarse conglomerate (from channel to wedge or sheetlike shaped), that sometimes can be dominant. the formation is also localities member (mb.) lithofacies (lt.) formations barga area t. loppora lenticular-shaped conglomerate (lt.) channel-shaped conglomerate (lt.) rio latrani sheet-like conglomerate (lt.) rio zanesi sheet-like conglomerate (lt.) corsonna fine grained (lt.) & channel-shaped conglomerate (lt.) le palmente lenticular-shaped conglomerate (lt.) & sandy (lt.) casa volpaia fine grained (lt.) and organic-rich horizons & channel-shaped conglomerate (lt.) pieve di loppia-barga road lenticular-shaped conglomerate (lt.) & sandy (lt.) barga lenticular-shaped conglomerate (lt.) & sandy (lt.) castelnuovo g. area rio dezza mt. alfonso (mb.). poorly sorted conglomerate il colle mt. alfonso (mb.). poorly sorted conglomerate mt. alfonso mt. alfonso (mb.). poorly sorted conglomerate s. lucia lenticular-shaped conglomerate (lt.) & sandy (lt.) castegni lenticular-shaped conglomerate (lt.) & sandy (lt.) soffiana sand and silty (lt.) & rare organic-rich horizons bamborino lenticular-shaped conglomerate (lt.) & sandy (lt.) liana sandy (lt.) & lenticular shaped conglomerate (lt.) barga area rio secco fine grained (lt.) & channel-shaped conglomerate (lt.) cava fornaci fine grained (lt.) t. loppora channel-shaped conglomerate (lt.) & fine grained (lt.) le palmente fine grained (lt.) rio cavo fine grained (lt.) & channel-shaped conglomerate (lt.) rio zanesi fine grained (lt.) & channel-shaped conglomerate (lt.) rio val di lago fine grained (lt.) and organic-rich horizons & channel-shaped conglomerate (lt.) corsonna fine grained (lt.) & channel-shaped conglomerate (lt.) rio della giuvicchia fine grained (lt.) and organic-rich horizons & channel-shaped conglomerate (lt.) casa volpaia fine grained (lt.) & channel-shaped conglomerate (lt.) castelnuovo g. area rio dezza fine grained (lt.) & channel-shaped conglomerate (lt.) rio la fossa fine grained (lt.) and organic-rich horizons & channel-shaped conglomerate (lt.) collemandina fine grained (lt.) & sandy (lt.) bamborino fine grained (lt.) la bottegaccia fine grained (lt.) & organic-rich horizons gamberone fine grained (lt.), organic-rich horizons & sandy (lt.) antisciana fine grained (lt.) & channel-shaped conglomerate (lt.) belvedere fine grained (lt.) & channel-shaped conglomerate (lt.) rio valardino fine grained (lt.) & channel-shaped conglomerate (lt.) c o n g lo m e ra ti d i b a rg a a rg ill e , s a b b ie e c o n g lo m e ra ti d i f o rn a c i d i b a rg a tab. 2 most significant outcrops in the barga and castelnuovo garfagnana depressions of the “argille, sabbie e conglomerati di fornaci di barga” and “conglomerati di barga” formations. exposed lithofacies are also synthetically described. affioramenti maggiormente significativi nelle aree di barga e castelnuovo garfagnana delle formazioni delle “argille, sabbie e conglomerati di fornaci di barga” e dei “conglomerati di barga”. sono anche descritte in modo sintetico le litofacies caratteristiche affioranti. characterized by a variable amount of centimetric to decimetric lignite fragments, that in places are abundant and concentrated in organic-rich horizons (fig. 3a). the fine grained deposits, ranging from 0.5 to 3-7 villafranchian deposits of the barga ... 318 m in thickness, are usually organized in centimetric to decimetric rhythmical alternance of grey-dark, grey to bluish or violet clay to silty-clay and yellowish silty or sandy beds, with horizontal to cross or through lamination, in places well evidenced by small lignite fragments. they can be associated with 0.5 to 3.5 m thick massive to horizontal laminated organic-rich clay or silty to sandy interbeddings, that somewhere show soft deformation structures. the organic-rich levels, more abundant in the lower portion of the formation, contain scattered lignite fragments, that can concentrate in 20 to 40 cm thick horizons, with limited (10-15 m) lateral extent. the sandy intervals, usually 10-20 cm thick and up to 1.5-2 m wide, can be up to 1.5 m thick and 10 m wide. in the thickest sandy levels, thin to medium thick lens-shaped conglomerate can be present. at different levels, and mainly within the clay and silty-clay intervals centimetric to decimetric (20-30 cm), dark grey paleosols containing land fossils (landi et al., 2002-2003) are present. unfortunately, the lateral extent of these horizons is limited and their correlation unreliable. the scarce fossil remains of the fine grained lithofacies include ostracods and gastropods, along with extremely rare teeth of fish and charophites oogonia (genus and species names in landi et al., 20022003). fragments of leaves and chunks of trees are also present and in few places the latter are still observable in life position (rio dezza). the isolated channel-shaped, clast-supported polymictic conglomerate, from grey/dark grey to brownish, consist of sub-rounded to well rounded clasts, in places imbricated. this medium to coarse grained massive and well sorted conglomerate shows a low percentage of silt to fine matrix, not always present. this deposit, with weak to strong erosive basal surface and limited (3-5 to 15-20 m) lateral extent, ranges from 1 to 3 m in thickness. the coarse grained lithofacies can also be represented by an alternance of clast-supported, wedgeto sheet-like conglomerate or sandy conglomerate, and medium to coarse sand. this conglomerate, from 1 to 3 m thick and up to 20-40 m wide, lacks any evidence of basal erosive surface. the pebbles and cobbles range from sub-angular to sub-rounded/rounded. the medium to coarse sandy matrix is present in variable amount, that can vary in percentage at metric scale. the sandy interbeds range from massive to cross laminated. in both types of conglomerate, the clasts are mainly represented by unmetamorphosed lithotypes, with the arenaceous clasts (referable to the macigno fm.) slightly more abundant than the carbonatic ones. in places, the arenaceous clasts can be dominant. the metamorphic (landi et al. 2002-2003) ones are more abundant in the barga (up to 15-20%) than in the castelnuovo garfagnana area, where they are extremely rare (below 1%). scattered along the apenninic border, afb is interbedded, at different levels, with medium/coarse to very coarse grained, monomictic, massive conglomerate, mainly made of clasts referable to the macigno fm. (i.e. units 3 and 4 of landi et al., 2002-2003). this unsorted to poorly sorted, matrixto clast-supported conglomerate is nicely exposed at colle buvicchia and mologno. it chiefly consists of sub-angular to rounded cobbles and boulders, in places well imbricated. the medium to coarse sandy matrix is furnished by the macigno fm. weathering. ranging in thickness from few metres up to 100 m, such coarse clastic wedges (in places) can represent the entire villafranchian sedimentary record. according to landi et al. (2002-2003), the association of fine and coarse grained lithofacies with in situ accumulated organic matter (mainly represented by lignite) was sedimented in a braided fluvial system, referable to an anabranching organo-clastic substage (sensu nanson & knighton, 1996), flowing from castelnuovo garfagnana to barga. it interfingers with the alluvial fan deposits (dominated by debris-flow processes), cropping out along the apenninic border (i.e. units 3 and 4 of landi et al., 2002-2003), and develops transversally to the tectonic depression axis. the thickest exposures range from 10-40 to 80 m in the barga area and from 10 to 30-40 m in the castelnuovo garfagnana area. the maximum thickness of this formation measured near castelnuovo garfagnana, including a drilled portion, can reach 200 m (de marco & caielli, 1995; cancelli et al., 2002). usually, the outcrops are not thicker than 10-30 m in barga as well as in castelnuovo garfagnana areas. the unconformable contact with the underlying formations is exposed in few localities, with bad exposure conditions and very limited lateral extent. along the eastern border of the barga depression, the macigno fm. is topped by the basal coarse grained and poorly sorted conglomeratic lithofacies of afb. in the boreholes drilled near villa collemandina, the substratum (represented by ligurian successions) has been reached below 90-100 m of afb. the afb/plb contact is frequently well exposed and characterized by an abrupt facies change, suggesting a possible disconformity surface. nevertheless, in some places (gallicano and barga areas) the heteropy between the two formations is not excluded. in fact, conglomeratic interbeddings are locally present in the uppermost part of afb; they are similar to those interbedded in the lowermost part of plb. in other areas, afb is topped by the erosive post villafranchian coarse grained terraced deposits. according to the quoted fossil remains, the lowermost portion of this formation could be assigned to the lower villafranchian, whilst its upper portion could reach the middle villafranchian. 4.2. conglomerati di barga (puccinelli et al., in press, a) synonymies ghiaie con prevalenza di rocce mesozoiche e metamorfiche (nardi, 1961) ciottoli e sabbie di loppia (calistri, 1974) conglomerati a ciottoli prevalentemente calcarei (nardi et al., 1986) ghiaie e conglomerati calcarei (nardi et al. 1987) conglomerati di barga (catanzariti et al., 2002) lithostratigraphic unit 2 (landi et al., 2002-2003) significant outcrops (see tab. 2) barga: t. loppora, rio latrani, rio zanesi, le palmente, pieve di loppia-barga road, barga and casa volpaia. castelnuovo garfagnana: bamborino, rio dezza, il colle, s. lucia, castagni, soffiana, mt. alfonso and liana. n. perilli et al. 319 fig. 3 main litholological features of the “argille, sabbie e conglomerati di fornaci di barga” fm. (a) and of the “conglomerati di barga” fm. (b). colonne stratigrafiche mostranti le principali caratteristiche litologiche delle “argille, sabbie e conglomerati di fornaci di barga” (a) e dei “conglomerati di barga” (b). villafranchian deposits of the barga ... plb is characterized by the dominance of medium to coarse (from pebbles to cobbles) grained lithofacies, whilst sandy to silty-clayey levels, with very rare paleosols, are subordinate. though texture, sedimentary structures and shapes of the conglomerate can change even at metric scale, two end-members can be described: one shows sheet-like geometry and significant presence of sand interbeddings, the other is lens-shaped and characterized by erosive basal surface and small amount of matrix (fig. 3b). the sheet-like, clast-supported conglomerate, with massive to crude bedding is interbedded with thin (2-3 to 5-10 cm), massive to horizontally stratified, lenticular yellowish sand. these coarse grained intervals, with very rare sedimentary structures, mainly consist of poorly to moderately sorted conglomerate, with well rounded pebbles and cobbles, rarely imbricated and with a variable amount of sandy-silty to silty matrix; the matrix percentage may change even within the same interval. this disorganized to poorly organized conglomerate, frequently ranging in thickness from 0.5 to 1 m, can be up to 3 m thick and 20-30 m wide. the lens-shaped, medium to coarse conglomerate, is chiefly composed of well sorted clasts and small percentage of silty to sandy matrix. the sub-rounded to rounded clasts are frequently imbricated and the matrix can be, in places, either absent or significantly present. this conglomerate, sometimes channellized, shows weakly erosive basal surface and planar to through cross stratification. ranging in thickness from 0.5 to 3 m, it can be up to 20-30 m wide. within this conglomerate, thin to thick (10-50 cm) interbeddings of massive, brownish to brown-reddish sand, with small lateral extension, are present. in both types of conglomerate, the clasts are chiefly represented by non-metamorphic or metamorphic carbonatic lithotypes; whilst sandstone (referable to the macigno fm.) is subordinate. within the coarse grained lithofacies, interbeddings of silt and fine to medium grained yellowish to reddish sand, up to 1 m thick, are present. more abundant in the sheet-like conglomerate and sometimes bioturbated, silt and sand frequently show through and planar cross-bedding. in places, grey to dark-grey, millimetric to centimetric lenses of clay evidence the sedimentary structures of these fine grained interbeddings. plb is also characterized by the occurrence of centimetric to decimetric rhythmical interbeddings of grey clay or silty-clay to sandy beds, with horizontal to cross or through lamination, similar to those described for the underlying formation. these fine grained lithofacies, usually ranging from few decimetres to 1-2 m (rio latrani, rio sartoiani, t. giuvicchia and t. corsonna), are up to 20 m thick at casa volpaia. in the silty-sandy or sandy beds micro and macro vegetable remains may concentrate and at different levels, centimetric to decimetric dark grey or blackish paleosols are also present. in all quoted localities, the heteropic transitions with the coarse grained deposits are visible. as reported by landi et al. (2002-2003), the described lithofacies association is dominated by conglomerate together with sandy lenses and centimetric to decimetric alternance of fine grained deposits (characterized by organic-rich horizons and paleosols). this association is referable to a gravel bed-load braided river system, flowing from ne to sw (i.e. from castelnuovo garfagnana to barga). as described for afb, along the apenninic border, also plb, interfingers with coarse grained lithofacies (unit 3 of landi et al., 2002-2003), characterized by sub-angular to rounded (the boulders) clasts, chiefly consisting of sandstone (referable to the macigno fm.), and interpreted as coalescent alluvial fan deposits (dominated by debris-flow processes) developed transversally to the tectonic depression axis. plb is superbly exposed along the oriental side of the serchio valley, and ranges in thickness from 70 (gallicano) to 170 m (barga). the better exposures are located between loppia and barga and in the villa collemandina area. usually, the outcrops can be 20-40 m thick and from 100 to 200 m wide. the clearly erosive contact between the conglomerati di fornaci di barga and the post villafranchian coarse grained terraced deposits is frequently well exposed. according to the few listed paleontological remains, this formation could be assigned to the middle to late villafranchian. west of the castelnuovo garfagnana area, plb is represented by medium to coarse clast-supported conglomerati of mt. alfonso member (unit 5 of landi et al., 2002-2003). showing a tabular geometry with thickness ranging from 0.5 to 3 m, these deposits can vary even in a short distance from disorganized to organized sedimentary body. the poorly sorted clasts, with a diameter up to 50 cm, in places imbricated, are mainly composed of carbonate, whilst the presence of sandstone is subordinate, though sometimes it can be significantly present. the 100 (westard) to 40 m (eastward) thick mt. alfonso member is interpreted as a braided fluvial fan, supplied by the apuan alps and developed transversally to the basin axis (landi et al. 2002-2003). 5. conclusive remarks on the basis of the main lithostratigraphic and sedimentological features of the described villafranchian succession, the following points should be emphasized. in the barga and castelnuovo garfagnana areas, afb and plb are characterized by distinctive lithofacies associations, and the boundary between the two formations is quite easily recognizable. within afb, clay and conglomerate are subordinate and the formalized name points out the wide lithological spectrum, that characterizes this formation. nevertheless, lateral and vertical variations between fine grained and coarse grained lithofacies are distinguishable at outcrop scale, but hardly mappable, due to their limited thickness and lateral extent. the clayey intervals of afb are more widespread and thicker in the castelnuovo garfagnana than in the barga depression, whilst sandy intervals are thicker and wider in the barga than in the castelnuovo garfagnana area. thin to very thin and well stratified, clayey-silty to sandy laminated (varve-like) intervals are peculiar of the castelnuovo garfagnana area. the organic-rich horizons within afb are relatively more abundant in the lower portion of the formation. they are usually represented by centimetric to decimetric horizons within the fine grained portions. the largest fragments of lignite and the chunks of trees 320 n. perilli et al. are scattered throughout the formation, and some of these latter are sometimes still in life position. the lignite banks, including the mined ones, are thicker and more continuous than those cropping out or mined in the barga area. in afb the coarse grained intervals are mainly represented by channelized conglomerate interbedded by clayey-silty or sandy dominant lithofacies. likewise, the sheetlike conglomerate (almost absent in the castelnuovo garfagnana area), present in the lower portion of the formation, is associated with clayeysilty or sandy lithofacies. in spite of the lateral and vertical lithological variation of the different lithofacies, the dominance of the coarse grained conglomerate allows the easy mapping of the plb, also characterized by sandy interbeddings. silty-clayey to sandy fine grained lithofacies (with thin organic-rich horizons similar to those present in afb), with reduced thickness as well as lateral extent, are clearly in heteropy to the conglomerate. also in the castelnuovo garfagnana area these lithofacies (including organic-rich horizons) are very limited in thickness and lateral extension. lignite fragments or other biogenic remains, as well as paleosols, are extremely rare and scattered within plb. indeed, large lignite fragments can be present within the coarse grained lithofacies, whilst millimetric to centimetric lignite flakes are relatively more frequent within the finest grained lithofacies. in the castelnuovo garfagnana depression, within the plb, the mt. alfonso member is distinguishable. mainly consisting of polymictic, poorly sorted medium to coarse conglomerate and subordinate coarse grained sand, it can be correlated with the conglomerate cropping out in the gallicano area (d’amato avanzi & puccinelli, 1988) and mapped within the plb. in spite of similar lithologies present in both formations, the lithofacies assemblages point out the superposition of gravel bed-load braided river deposits (plb) on cohesive sediment anabranching river deposits (afb). both successions interfinger with the alluvial fan conglomerate, that in places can represent the entire villafranchian succession. the abrupt facies change between these two clastic successions can be interpreted as a disconformity surface (landi et al., 2002-2003). unfortunately, it is neither supported by paleontological data nor confirmed by other field evidence. however, the conglomeratic lithofacies interbedded within the afb shows neither a polarity towards the top of the formation nor significant similarities with the coarse grained lithofacies of the plb. on the other hand, the erosive contact between afb and plb can be also interpreted as stratigraphic, because erosive surfaces are frequent within this type of deposits (from anabranching to gravel bed-load braided). moreover, the presence of channellized conglomeratic lenses within the uppermost part of the afb, similar to those present in the overlying lowermost part of plb, can support (at least in some places) a quite sharp but transitional boundary between afb and plb (puccinelli et al., in press, a). in summary, though the villafranchian clastic wedges sedimented in two distinct tectonic depressions, connected by the sedimentary by-pass (landi et al., 2002-2003) of the “mt. perpoli high”, active since the beginning of the villafranchian deposition, the lithofacies associations characterizing afb as well as plb are quite similar in both areas. furthermore, the boundary between afb and plb shows the same features in both depressions, even if the field evidence is not helpful to choose between the existence of a disconformity or a stratigraphic transition between afb and plb. although the correlation between continental clastic successions, not supported by sedimentological analysis and paleontological data is difficult, in our opinion the afb and plb can be correlated with the “argille, sabbie e conglomerati di aulla” and the “conglomerati di olivola”, respectively (puccinelli et al., in press, b). both crop out north-westward in the magra valley (aulla-olivola and pontremoli tectonic depressions) and show strong affinities with afb and plb. the “argille, sabbie e conglomerati di aulla” consists of fine grained lithofacies characterized by a variable amount of centimetric to decimetric lignite fragments and organic-rich horizons, with medium to thick coarse grained sandy conglomeratic interbeddings. the overlying “conglomerati di olivola” is 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[ser. a], 94, 105-117. puccinelli, a., d’amato avanzi, g. & perilli n., in press (a) carta geologica d’italia a scala 1:50.000 note illustrative del foglio 250 castelnuovo di garfagnana. puccinelli, a., d’amato avanzi, g. & perilli n., in press (b) carta geologica d’italia a scala 1:50.000 note illustrative del foglio 234 fivizzano. tongiorgi e. & trevisan l., 1953 excursion en garfagnana et aux alpes apouanes. iv congrès inqua, roma-pisa, tip. giard., pisa, 1-11. ugolini r.,1902 vertebrati fossili del bacino lignitifero di barga (val di serchio). atti soc. tosc. sc. nat., proc. verb., 13, 32-36. zaccagna, d.,1917 le ligniti di ghivizzano in val di serchio. roma, febbraio 1917. zaccagna, d.,1932 descrizione geologica delle alpi apuane. mem. descr. carta geol. it., 25, 440 pp. 322 ms. ricevuto il 21 maggio 2004 testo definitivo ricevuto il 12 ottobre 2004 ms. received: may 21, 2004 final text received: october 12, 2004 n. perilli et al. imp. cinque-irollo iill ““vvuullccaannoo ddii ppoommppeeii””:: nnuuoovvii ddaattii ggeeoommoorrffoollooggiiccii ee ssttrraattiiggrraaffiiccii aallddoo cciinnqquuee11 && ggiioolliinnddaa iirroolllloo11 1dipartimento di scienze della terra, università degli studi “federico ii”, largo s. marcellino, 10 –80138napoli cinque@unina.it. riassunto: cinque a. & irollo g. – il “vulcano di pompei”: nuovi dati geomorfologici e stratigrafici – (it issn 0394 3356, 2004) lo studio geomorfologico e stratigrafico condotto ha permesso di confermare, in modo definitivo, che la collina su cui sorge l’antica pompei, precedentemente ritenuta una forma impostata su lave discese dal somma-vesuvio, rappresenta il relitto di un edificio vulcanico indipendente. esso è parzialmente sepolto dalla falda meridionale del somma-vesuvio e dai depositi che hanno aggradato la prospiciente piana del sarno, nel corso del tardo quaternario. l’ossatura del rilievo principale (“arco della civita”) che si segue, con andamento planimetrico semicircolare, dalla località sette termini fino al limite se della antica pompei, è formata da colate laviche e prodotti di attività stromboliana (tra cui una tipica foam lava segnalata già da vitruvius) che si sovrappongono ad un rilievo a tufi e piroclastiti sciolte, già all’epoca fagliato ed eroso. all’arco della civita si associano, inoltre, piccoli edifici prevalentemente scoriacei (cratere di via di stabia, rilievo di s. abbondio) che sembrano ubicarsi lungo fratture anulari, più o meno coassiali con l’edificio principale. a punti di emissione analoghi possono, infine, riferirsi almeno parte delle lave ritrovate nel sottosuolo della piana poco a s e se della collina pompeiana. la metà orientale del composito edificio vulcanico (non affiorante) potrebbe essere stata ribassata di alcune decine di metri da una faglia orientata all’incirca nw-se. una importante faglia e-w, che ribassa di un migliaio di metri verso n il substrato pre-quaternario della piana del sarno, sembra, invece, costituire il motivo strutturale che controlla l’ubicazione dell’intero apparato pompeiano. la frazione dell’edificio a tufi e piroclastiti è, al momento, di difficile datazione, anche se l’analisi dei suoi rapporti con altre unità del sottosuolo suggerisce un’età post ignimbrite campana (39 ka) e, forse, posteriore anche ad una fase di dissezione della piana del sarno occorsa durante l’ois 2. la successiva fase ad attività stromboliana ed emissioni laviche ricopre un intervallo temporale che va da oltre 19 ka (lave presso la porta nocera) fino all’olocene antico quando le ultime colate discendenti lungo il fianco s e sw della collina pompeiana si intercalarono ai sedimenti trasgressivi versiliani della bassa piana del sarno. abstract: cinque a. & irollo g. – the “pompeii volcano”: new geomorphological and stratigraphical data – (it issn 0394 3356, 2004) by means of both detailed geomorphological investigations and analysis of pre-existing drilling data, the small hills occurring in the area of pompeii (province of naples; italy) have been definitely recognized as volcanic landforms and attributed to the activity of local vents. the main relict of what we call the pompeii volcano consists in a crescent-shaped ridge (“arco della civita) that is tentatively interpreted as the remnant of an ancient volcanic ring. it stretches from sette termini, near boscoreale, to the archaeological site of the ancient town of pompeii. further to the north, it is buried by lavas and pyroclastics forming the southern piedmont of somma-vesuvius volcano. southwards it is buried by the late quaternary sediments of the sarno rives alluvial coastal plain. the eastern half of the ancient ring, which does not crop out, may have been lowered by some tens of meters because of a se-trending normal fault. a geological section across the arco della civita crescent, shows that the structure has a core of tuffs and loose pyroclastic beds; suggesting that the initial activity of pompeii volcano was essentially explosive. this pyroclastic edifice was then locally covered by lava flows and scoria (leucite bearing tephrites) coming from a number of local vents, among which is the small s. abbondio cone and, probably, the one we named via di stabia crater. their products (such as the typical foam lava, already known to vitruvius) were abundantly utilized as building materials in ancient pompeii. on the base of their relations with other dated formations, the various emissions of lava appear to vary in age from place to place: they are older than 19 ky close to porta nocera and early holocene in age (likely 8÷6 ka) in the sw flank of the pompeian hill where the lava flows interfinger with the transgressive versilian sediments of the lower sarno river plain and appear cut by a sea-cliff to be acribed to the peaking stage of the same post-glacial trasgression. more difficult to date is the explosive activity which occurred before lava and scoria emissions. some sub-surface stratigraphic data prove that it is not older than the tyrrhenian stage (ois 5) and possibly younger than the ois 3. other stratigraphical and palaeomorphological data suggest that the explosive activity of pompeii volcano occurred when the campanian ignimbrite (39 ka) had already been dissected by the sarno river. the existence and the position of the studied volcano can be connected to an important e-w trending normal fault which is perfectly buried by the thick quaternary fill of the sarno plain, but nicely revealed by gravimetric and magnetic anomalies. this fault lowers the substrate of the plain (mesozoic to neogene units of the apenninic chain) by approximately one thousand meters to the north and it can be followed from nocera inf. to torre annunziata. the pompeii volcano could be at the intersection of this fault with another, nw trending regional fault or with a radial fracture of the somma-vesuvius volcano. parole chiave: geomorfologia vulcanica; tardo quaternario; apparato del somma-vesuvio. keywords: volcanic geomorphology; late quaternary; somma-vesuvius volcano. il quaternario italian journal of quaternary sciences 1177(1), 2004, 101-116 102 a. cinque & g. irollo 11 - iinnttrroodduuzziioonnee i resti dell’antica città di pompei, fondata intorno al vi secolo a.c. da popolazioni osche e distrutta dalla celebre eruzione vesuviana del 79 d.c., sorgono su un rilievo collinare che, sebbene di modesta altezza (quota massima 54 m s.l.m.), ben si staglia sulla circostante pianura alluvionale costiera del fiume sarno. verso nw la collina pompeiana si fonde quasi perfettamente col piedimonte dell’edificio vulcanico del somma-vesuvio (fig. 1) e ciò ha a lungo indotto a considerarla come una forma impostata su colate laviche discese da tale edificio. questa interpretazione è indicata anche nel foglio n. 185 “salerno” della carta geologica d’italia, il quale include le lave presenti nell’area pompeiana in un’unità cartografica [β: lave protostoriche, (ottavianiti augitiche), in parte sepolte nella pianura] che raggruppa numerose colate provenienti dal somma-vesuvio. come sarà meglio illustrato nel terzo capitolo, alcuni autori (ippolito, 1962; di girolamo, 1969; cinque, 1991; di vito et al., 1997, 1998a-b) hanno successivamente fornito indicazioni che fanno invece propendere per un’origine locale delle vulcaniti formanti l’ossatura della collina pompeiana. il presente lavoro intende contribuire alla conoscenza geologica dell’area di pompei ed in particolare ad accertare l’esistenza di un edificio vulcanico locale ed a definirne la morfologia. si è tentato, inoltre, di fornire un preliminare inquadramento cronologico delle vulcaniti pompeiane, basandosi sui loro rapporti stratigrafici e geomorfologici con marker piroclastici regionali e con gli episodi eustatici trasgressivi che hanno interessato l’area di studio nel corso del tardo quaternario. la ricerca, svolta senza finanziamenti specifici, non ha potuto avvalersi di sondaggi ed analisi realizzati allo scopo, basandosi, invece, su un attento rilevamento geologico e geomorfologico, nonché sulla raccolta e rielaborazione di preesistenti dati stratigrafici, petrografici, geocronologici e geofisici. l’ampio ricorso a dati di sottosuolo è motivato dalla pressoché totale copertura degli intervalli di interesse da parte di unità sedimentarie e piroclastiche più recenti. nell’area dell’antica pompei, dove la copertura è più esigua, alcune informazioni sui litotipi che formano l’ossatura della collina sono state ricavate da relazioni di scavo e sondaggio archeologici. l’analisi geomorfologica è stata basata, oltre che su osservazioni dirette, sulla interpretazione di foto aeree e sull’esame di carte topografiche in scala 1:5000, 1:2000 e, per l’area degli scavi di pompei, 1:500. 22 - iinnqquuaaddrraammeennttoo ggeeoollooggiiccoo ddeellll’’aarreeaa l'area di studio si colloca nella zona di raccordo tra le pendici sud-occidentali del somma-vesuvio e la piana alluvionale costiera del fiume sarno (fig. 1). essa ricade nella parte meridionale della ampia depressione tettonica nota in letteratura come graben campano (ippolito et al., 1973; ortolani & aprile 1978), la cui parte settentrionale, al di là del somma-vesuvio e dei campi flegrei, è occupata dalla ben più vasta piana del volturno. il graben campano ribassa le unità della catena sud-appenninica fino a circa 3000 m sotto il livello del mare e deve la sua origine a fagliazioni estensionali occorse a partire dal pleistocene inferiore (brancaccio et al., 1991). la subsidenza è stata accompagnata da una attività vulcanica alimentata da magmi inizialmente di tipo calc-alcalino (vulcani profondamente sepolti sotto la pianura) e poi di tipo k-alcalino (edifici tardo quaternari oggi visibili: campi flegrei, somma-vesuvio, vulcani delle isole di nisida, procida, vivara ed ischia) (barbieri et al., 1979; bernasconi et al., 1981; brocchini et al., 2001). oltre che ai prodotti vulcanici, il parziale colmamento della depressione, ovvero la nascita della piana campana, va imputato all’accumulo di una potente successione sedimentaria alimentata dagli apporti dei fiumi appenninici. come mostrano le facies attraversate da alcuni sondaggi profondi (ippolito et al., 1973; barbieri et al., 1979; romano et al., 1994; barra et al., 1996) nel corso del quaternario il graben è stato spesso sede di un golfo marino che, influenzato dalle interferenze tra eustatismo e subsidenza, si è spinto più volte fino alla base, o quasi, dei primi rilievi appenninici. a seguito della regressione dell’ultimo massimo glaciale, la linea di costa avanzò fino al ciglio della piattaforma continentale, che, al largo dell’area di studio (golfo di napoli), si trova a circa 20 km oltre la costa attuale (milia & torrente, 1999). tale ingente avanzamento della linea di riva fu anche favorito dagli accresciuti ritmi di colmamento vulcanico e sedimentario (crescita dell’edificio del somma-vesuvio, eruzione della potente ignimbrite campana, estendersi dei conoidi alluvionali discendenti dai monti lattari). la conseguente aggradazione della piana impedì, quindi, alla trasgressione versiliana di produrre un’ingressione paragonabile a quella del precedente interglaciale. infatti la paleolinea di riva versiliana più interna (associata a torbe datate 5,6 ka; cinque, 1991) si spinge solo fino all’altezza di scafati, mentre successivi lineamenti costieri marcano la progressiva progradazione, avvenuta nel corso dell’olocene recente, nonostante una contemporanea subsidenza al ritmo medio di circa 2 mm/a (cinque, 1991). per la datazione degli eventi che hanno interessato l’area nel corso del tardo-quaternario, particolare utilità rivestono alcuni livelli guida connessi ad eruzioni esplosive di età nota. i più antichi tra questi marker sono l’ignimbrite di taurano (157 ka circa, rolandi et al., 2000) e la potente ed estesa ignimbrite campana, o tufo grigio campano (i. c.) datata recentemente a circa 39 ka (rolandi et al., 2000; de vivo et al., 2001), a composizione trachitica. alcuni autori ne connettono la genesi al collasso della caldera flegrea (rosi & sbrana, 1987; orsi et al., 1996; civetta et al., 1997); altri la attribuiscono, totalmente o parzialmente, ad eruzioni fissurali lungo faglie dissecanti più ampie porzioni della depressione campana (scandone et al., 1991; cinque et al., 1997; rolandi et al., 2003). tra i marker tefro – stratigrafici potenzialmente utili in questo lavoro, vanno poi considerati, il tufo giallo napoletano, datato a circa 12 ka (scandone et al., 1991) ed alcune grandi eruzioni pliniane del somma – vesuvio, quali quelle “di codola” (circa 25 ka, arnò et al., 1987), “di sarno” o delle pomici di base (19 ka, bertagnini et al., 1996), delle “pomici verdoline” (circa 17 ka, arnò et al., 1987), “di ottaviano” o “di mercato” (8 ka, rolandi et al., 1993), “di avellino” (circa 3,6 ka, arnò et al., 1987) e “di pompei” (79 d.c.) (andronico et al., 1995; 96; arnò et al., 1987). 103il “vulcano di pompei”: nuovi dati geomorfologici e stratigrafici fig. 1 schema geomorfologico dell’area pompeiana. main geomorphological features of pompeii area. 104 33 -pprreecceeddeennttii ccoonnoosscceennzzee ssuullllee ffoorrmmaazziioonnii vvuullccaanniicchhee ddeellll’’aarreeaa ppoommppeeiiaannaa un primo riferimento ai materiali lavici affioranti nell’area di pompei, ed utilizzati per la realizzazione di opere murarie, emerge già nel trattato “de architectura” (ii, vi, 2) di vitruvius laddove l’autore parla della “spongia, sive pumex pompeianus”. il termine spongia compare in vitruvius solo in questo passo ed è assente negli autori latini ed in particolare nella “naturalis historia” di plinius1. ruggiero nel 1879 indica, nella città antica, la presenza di una lava compatta nel teatro coperto e nel triclinio della casa 3, reg. 1, ins. 2, (“e” in fig. 2) simile a quella ritrovata in un pozzo, lungo la strada di sette termini, nella vigna cerulli, ad un chilometro circa da pompei, e definita leucitite porfirica, con abbondanti cristalli di augite e più rari di leucite. descrive, inoltre, un termine scoriaceo nella “ripa di mezzogiorno”, sotto il tempio greco, ed in quella occidentale, rilevando le analogie delle scorie pompeiane con i prodotti che si cavavano a pollena, lungo le opposte pendici del vesuvio. nicotera (1950) analizza in dettaglio e classifica le rocce utilizzate a pompei come materiali da costruzione e per i lastricati stradali. sottolinea inoltre l’importanza del substrato lavico della collina per le opere di fondazione degli edifici e l’uso differenziato, in campo edilizio, dei materiali di risulta delle operazioni di scavo e di coltivazione delle cave. in tempi più recenti di girolamo (1968; 1969) descrive lungo la paleofalesia che margina a meridione il sito archeologico (“a” in fig. 2) delle lave vacuolari e scoriacee, di colore rosso e con fenocristalli di leucite, augite ed olivina. l’autore le classifica come “tefriti leucitiche a tendenza basanitica” e vi riconosce i caratteri tipici di foam lava prossimale, da attribuire ad una bocca eruttiva locale. lo stesso di girolamo (1963) segnala, nella zona dell’anfiteatro, (“c” in fig. 2) anche un livello lavico di colore grigio, a tessitura compatta e con composizione affine che evidenzia analogie di carattere chimico, fisico e petrografico con la colata di castello di cisterna, alla base del versante orientale del somma-vesuvio. nella successione stratigrafica ricostruita per pompei la colata dell’anfiteatro è, secondo di girolamo (1968), antecedente alla foam lava. la sovrapposizione di termini lavici scoriacei su quelli compatti, oltre ad emergere da molti dati di sottosuolo qui presentati (vedi oltre), è stata riconosciuta anche da rolandi et al. (1997) lungo il margine meridionale della stessa collina pompeiana. essa è stata rilevata, ancora, all’interno di un pozzo per acqua realizzato nella “casa dei vasi di vetro” nel 1931 (sondaggio "po2a" in fig. 2 e 3) ed in un pozzo di età classica adiacente a porta vesuvio (sondaggio "po2b" in fig. 2 e 3) (ippolito, 1938; 1962; nicotera, 1950; maiuri, 1973). secondo ippolito (1938) le lave di porta vesuvio sono simili a quelle affioranti, in forma più alterata, sotto il foro triangolare e nella “casa di giuseppe ii” (rispettivamente “g” ed “h” in fig. 2), nonché analoghe a quelle di castello di cisterna. tali analogie suggeriscono all’autore una attribuzione all’attività del somma recente. anche secondo bellucci (1998), nell’immediato sottosuolo dell’area di pompeiscafati sarebbe riconoscibile un complesso delle “lave del somma” che l’autrice descrive come una sequenza di colate laviche intervallate da livelli di scorie, che solo presso ottaviano e boscotrecase reca alla base depositi piroclastici riconducibili all’eruzione di codola, mentre altrove risulta direttamente sovrapposta all’ignimbrite campana. come si argomenterà più avanti, l’attribuzione a tale complesso delle lave affioranti sulla collina pompeiana appare poco sostenibile. l’ipotesi di un’origine somma-vesuviana potrebbe, invece, restare valida per almeno parte delle lave che ricorrono nel sottosuolo della piana, ad e e ne della stessa collina (vedi paragrafo 5.3 b). tali lave sepolte sono state segnalate anche da ruggiero, (1879); luongo & rapolla (1964); di girolamo (1969) e di vito et al. (1997; 1998a) i quali forniscono interessanti stratigrafie di sondaggio che hanno contribuito alle ricostruzioni presentate nel capitolo 5. per quanto riguarda i terreni presenti alla base delle lave pompeiane, ippolito, (1962) analizzando la stratigrafia del pozzo della casa dei vasi di vetro (sondaggio “po2a” fig. 2-3), fa notare che l’unità tufacea grigia, che è sottoposta alle due colate laviche, non può essere ascritta all’i. c. per riscontrate differenze chimiche, per l’abbondanza di clasti metamorfosati di calcare (della grandezza di un pugno) e di scorie, di dimensioni e frequenza tali da indurre l’autore a ritenere questo tufo di origine locale (distanza della bocca eruttiva valutabile in pochi chilometri). di diverso avviso sono di girolamo (1968) e rolandi et al. (1997) i quali, pur senza fornire nuovi dati analitici, correlano quel tufo alla ignimbrite campana. quanto ad indicazioni cronologiche, cinque & russo (1986) e cinque (1991) dimostrano che le lave e la collina di pompei precedono cronologicamente l’apice trasgressivo versiliano, mentre rolandi et al. (1997) segnalano che presso la porta nocera (scavi di pompei, “b” in fig. 2) le lave sono coperte da un livello di pomici da fall affini a quelle dell’eruzione “sarno”(19 ka). di vito et al. (1998a) forniscono delle misure di radiocarbonio che datano a circa 18 e 20 ka i paleosuoli intercalati alle lave in alcuni sondaggi effettuati lungo il confine meridionale della collina pompeiana (vedi discussione al capitolo 6). circa i termini che sono sottoposti alle lave in questione, dai quali potrebbero essere ricavati dei limiti di età massima per le stesse, rolandi et al. (1997) ipotizzano che le pomici presenti alla base delle lave nel pozzo della casa dei vasi di vetro (sondaggio “po2a” fig. 2-3) siano attribuibili all’eruzione di “codola” (circa 25 ka), mentre ippolito (1962), riporta l’attribuzione di rittmann al tufo giallo napoletano (circa 12 ka) del livello tufaceo immediatamente sottostante a tali pomici. per quanto concerne la morfologia associata alle vulcaniti pompeiane, il primo lavoro che riconosce nella collina di pompei scavi i resti di un edificio vulcanico distinto dal somma-vesuvio si deve a cinque (1991), il quale presenta tale interpretazione in una carta dedicata all’evoluzione tardo-quaternaria della piana del sarno. successivamente di vito et al. (1997) parlano di un “apparato eccentrico pompeiano” e d’ambrosio et al. (2001) riconducono a centri eruttivi locali le rocce scoriacee con proietti rinvenute in sondaggi sulla piana, effettuati lungo l’autostrada napoli-salerno. gli stessi autori individuano prodotti simili a quelli dell’area pom1secondo l’interpretazione del prof. maurizio bugno (università degli studi di napoli federico ii) quell’aspetto che la faceva riconoscere col termine scientifico e tecnico di pumex poteva localmente essere riconosciuto come spongia. a. cinque & g. irollo 105 f ig . 2 t o p o g ra fia d i d e tt a g lio d e ll’ a re a a rc h e o lo g ic a d i p o m p e i e t e n ta tiv o d i i n te rp re ta zi o n e g e o m o rf o lo g ic a . d e ta ile d t o p o g ra p h ic m a p o f p o m p e ii a rc h a e o lo g ic a l s ite w ith a n a tt e m p t o f g e o m o rp h o lo g ic a l i n te rp re ta tio n . il “vulcano di pompei”: nuovi dati geomorfologici e stratigrafici 106 f ig . 3 c o lo n n e s tr a tig ra fic h e d i a lc u n i d e i s o n d a g g i p re g re ss i u til iz za ti n e l p re se n te s tu d io ( l a t e rm in o lo g ia u til iz za ta in le g e n d a è q u e lla o ri g in a le d e lle d e sc ri zi o n i s tr a tig ra fic h e ; ve d i t e st o p e r la r e in te rp re ta zi o n e ). s tr a tig ra p h y o f so m e p re -e xi st in g w e lllo g s u se d in t h e p re se n t st u d y (t e rm s u se d c o rr e sp o n d t o t h e o ri g in a l d e sc ri p tio n s o f w e lllo g s; s e e t e xt f o r re -i n te rp re ta tio n s) . a. cinque & g. irollo peiana nel sottosuolo di scafati, ove ipotizzano l’esistenza di morfologie vulcaniche sepolte. 44 - oosssseerrvvaazziioonnii ggeeoommoorrffoollooggiicchhee come evidenziato in figura 1 l’area in esame può essere suddivisa nelle seguenti unità geomorfologiche principali: a) iill ppiieeddiimmoonnttee ssoommmmaa--vveessuuvviiaannoo, la cui geometria fondamentale ha simmetria radiale e profili trasversali dolcemente concavi (pendenze massime, a monte, intorno al 6%). esso raccorda lo strato-vulcano alla pianura e deriva da accumuli di deiezioni torrentizie alternate a piroclastiti da caduta e da flusso. a luoghi, in particolare nelle sue parti più prossimali, si notano dossi dovuti a colate laviche storiche e, poco fuori dell’area mappata in figura 1 a coni di scorie. b) llaa ppiiaannuurraa aalllluuvviioonnaallee ee ccoossttiieerraa ddeell ffiiuummee ssaarrnnoo, che ha una pendenza media, verso wsw, dello 0.2÷0.3% ed appare priva di sensibili articolazioni morfologiche. nella parte più occidentale della piana si individuano dei modesti dossi allungati in direzione nw-se (attenuati da successive aggradazioni alluvionali e piroclastiche e dalle azioni antropiche), che rappresentano paleocordoni costieri dell’olocene recente e si alternano a fasce sub pianeggianti corrispondenti a depressioni retrodunari. verso s e se, oltre i limiti della mappa di figura 1 la piana passa ai conoidi di deiezione che marcano il piedimonte dei monti lattari. c) ii rriilliieevvii ccoolllliinnaarrii ddeellll’’aarreeaa ppoommppeeiiaannaa, che appaiono come entità distinte dalle due precedenti e la cui geomorfologia è dettagliatamente descritta in seguito. d) llaa ppaalleeooffaalleessiiaa vveerrssiilliiaannaa che, nella zona di torre annunziata, taglia il piedimonte somma-vesuviano (cinque & russo, 1986) mentre, più ad oriente intacca, alla base, i rilievi della unità “c” e, fuori dall’area mostrata in figura 1, i sopra citati conoidi dei m. lattari. modellatasi durante la risalita eustatica postglaciale, essa è stata progressivamente disattivata, da e verso w, con le pulsazioni progradazionali che hanno caratterizzato la piana nel corso della seconda metà dell’olocene (cinque 1991). analizzando più in dettaglio i rilievi collinari pompeiani vi si possono distinguere un elemento nord occidentale, di maggiore altezza ed estensione, che denominiamo “arco della civita” e, ad e ed a se dello stesso, alcuni rilievi di estensione ed altezza più modeste quali il dosso presso il cimitero di pompei, il colle s. bartolomeo e la collinetta di s. abbondio. l’arco semicircolare della civita si estende dalla culminazione di sette termini (54 m s.l.m.) fino all’area archeologica di pompei. esso sovverte il regolare declivio verso sud del piedimonte somma-vesuviano disegnando una modesta risalita topografica (da cui la sella tra boscoreale e sette termini) ed inducendo un deciso cambiamento di orientazione delle isoipse. tale arco è caratterizzato da quote approssimativamente costanti lungo il suo sviluppo, a differenza del piedimonte vesuviano che declina regolarmente verso s. la prominenza del primo sul secondo è quindi chiara verso meridione e diviene progressivamente meno pronunciata in direzione di boscoreale. la geomorfologia della zona di contatto suggerisce abbastanza chiaramente che sono i materiali costituenti il piedimonte somma-vesuviano ad accavallarsi su quelli che formano l’arco della civita, sebbene non sia da escludere che, ad una certa profondità, i termini più antichi dell’edificio somma-vesuviano siano soggiacenti a quelli dell’arco stesso. il fianco esterno di quest’ultimo declina in modo radiale centrifugo con pendenze del 3÷6%. nel tratto compreso tra villa di diomede e porta di stabia (fig. 2) il pendio citato è tagliato alla base da un elemento più ripido -a luoghi sub-verticale-, che corrisponde alla già citata paleofalesia versiliana. per i rapporti con le paleolinee di riva datate nella bassa piana del sarno (cinque, 1991) si può ritenere che questo tratto di paleofalesia sia stato attivo durante l’olocene medio, per divenire poi una falesia morta con la crescita del paleocordone di bottaropioppaino (databile tra circa 3,6 e 2,5 ka). il fianco interno dell’arco ha un andamento all’incirca parallelo a quello esterno e declina in modo centripeto con pendenze del 3÷5%. nel settore tra civita giuliana e pompei scavi, tale fianco discende verso una zona piatta ed a contorno semi-circolare indicata col significativo toponimo di fossa di valle (quota minima 18 m circa s.l.m.). quest’ultima doveva essere in origine più profonda, e forse anche endoreica, essendo stata certamente interessata da recenti fasi aggradazionali, connesse alla potente eruzione del 79 d.c., alla trasgressione versiliana sulla limitrofa piana del sarno ed, infine, alla crescita del piedimonte vesuviano. un’apofisi di quest’ultimo penetra, infatti, da e nella depressione. l’insieme dei dati geomorfologici fin qui esposti appare già sufficiente a far riconoscere, nell’arco della civita, il relitto parziale (la metà occidentale) di un edificio vulcanico sub circolare il cui diametro apparente, misurato lungo l’attaccatura della pianura circostante, che in parte lo seppellisce, è stimabile intorno a 3 km. la reale altezza dell’edificio è certamente superiore al suo aggetto attuale sulla piana (circa 35 m), che ha subito sensibili fasi di aggradazione dopo la crescita dell’edificio stesso (vedi oltre). il basso morfologico di fossa di valle, sottodimensionato e decentrato rispetto all’arco della civita, può interpretarsi come il relitto di una depressione vulcanica minore, piuttosto che come espressione della depressione centrale dell’intero edificio. d’altra parte, la geomorfologia dell’area presenta diversi altri elementi a favore di una polifasicità dell’edificio, accompagnata da migrazioni delle attività costruttive e distruttive. ad esempio, nella zona a nord di fossa di valle, il rilievo isolato che denominiamo colle del cimitero (37 m s.l.m. fig. 1) sembra doversi interpretare come un lembo ribassato ed eroso del substrato a tufi e piroclastiti sciolte dell’edificio principale. a favore di tale ipotesi vi sono sia dati stratigrafici e giaciturali, (vedi capitolo seguente), sia un’incisione che sembra rimarcare, in susseguenza, una faglia nne ssw, tra detto colle e l’arco della civita (fig. 1). la collinetta di s. abbondio (18 m s.l.m. fig. 1) va attribuita all’attività costruttiva di una bocca eruttiva minore, sia per il suo ergersi isolata all’esterno del cerchio ricostruibile estrapolando l’arco della civita, sia in base a evidenze di ordine geologico fornite nel successivo capitolo. tracce di un altro possibile centro eruttivo secondario sono emerse all’interno del perimetro della città antica di pompei, ove è stata preliminarmente ricostruita la morfologia pre-scavo archeologico, su carte topografiche in scala 1:500 (aavv, 1994), sommando ai dati altitudinali lo spessore della coltre piroclastica asportata (5 107il “vulcano di pompei”: nuovi dati geomorfologici e stratigrafici m circa nel settore meridionale dell’area e 4 m circa in quello settentrionale) e considerando le modifiche indotte dagli stessi lavori di scavo (maiuri, 1960). come riportato in figura 2 la topografia così ricostruita evidenzia una forma semicircolare concava che suggerisce l’esistenza di un cratere secondario rispetto al più grande arco della civita (cratere di via stabia), troncato a s dalla falesia versiliana. sempre nell’ambito dell’area che fu occupata dall’antica pompei, si osserva un’ampia forma lobata che si allunga verso ese, con quote che decrescono dai 38 m della zona all’altezza di porta di nola a 22 m nell’area di palestra grande e dell’anfiteatro (rispettivamente“d” e “c” in fig. 2). questo lobo ha la sommità quasi appiattita e, sebbene non si possano escludere spianamenti antropici connessi alle fasi di antica urbanizzazione, si può ritenere credibile l’ipotesi che la sua forma complessiva sia da imputarsi ad espandimento di colate laviche, quali quelle individuate nel pozzo di palestra grande (luongo & rapolla, 1964), a porta di sarno, e presso l’anfiteatro. l’analisi geomorfologica ha consentito di riconoscere, oltre alle forme di origine vulcanica, diversi indizi di fagliazione diretta ascrivibili ad un’attività tettonica esplicatasi dopo la crescita dell’edificio vulcanico pompeiano e probabilmente anche durante la stessa. a tal proposito va citata, in primo luogo, la mancata evidenza morfologica della metà orientale dell’edificio, la quale va verosimilmente imputata ad un ribassamento (seguito da seppellimento) lungo una faglia con orientazione circa nw-se. (fig. 1). un’altra possibile faglia è quella, già citata, che separa il dosso del cimitero dall’arco della civita (fig. 1 e 4). lungo il regolare fianco esterno di quest’ultimo, nella zona di porta ercolano, è stata poi riscontrata una incisione ad andamento anomalo (non radiale) che potrebbe essere impostata lungo una faglia che si allunga da w verso se e ribassante, 108 fig. 4 sezione stratigrafica trasversale all’arco della civita (traccia in fig. 1). i sondaggi utilizzati sono quelli eseguiti dalla geosond soc. coop. a.r.l. nel 1989, ad eccezione di cg 64). geological section across the arco della civita (see fig. 1 for location). all drillings but cg 64 derive from the work carried out by geosond soc coop a.r.l. in 1989. a. cinque & g. irollo probabilmente di pochi metri, verso ne così da catturare e deviare i ruscellamenti centrifughi del pendio vulcanico (fig. 2). infine la faglia anulare che disegna o rinvigorisce il fianco interno dell’arco principale (fig. 1-4). 55 - ddaattii ssttrraattiiggrraaffiiccii sono stati raccolti ed interpretati numerosi dati geologici, relativi sia ad affioramenti, naturali ed artificiali, che a sondaggi meccanici eseguiti in passato sulla collina pompeiana e nei suoi dintorni, per ricerche idriche, per palificazioni e per la realizzazione di opere pubbliche. in totale sono state analizzate più di 200 stratigrafie di sondaggio l’ubicazione della maggior parte delle quali è mostrata nelle figure 1, 2, 7, 8 e 9. le stratigrafie di maggior interesse e complessità sono riportate in figura 3, mentre altre vengono riassunte nel testo. non sono invece citate, per motivi di brevità, quelle stratigrafie di sondaggio risultate utili solo a determinare la presenza di lave sepolte e le loro quote. in questo capitolo si esaminano i dati stratigrafici raccolti, raggruppandoli per aree e per temi. 55..11 - sseezziioonnee aattttrraavveerrssoo ll’’aarrccoo ddeellllaa cciivviittaa utilizzando congiuntamente dati di affioramento, osservazioni geomorfologiche e dati litostratigrafici e giaciturali emersi durante lo studio e la realizzazione di una galleria lungo il canale conte di sarno (cogefar impresit s.p.a.; geosond soc. coop. a.r.l., 1989), è stato possibile costruire una sezione geologica trasversale all’arco della civita (fig. 4). in essa sono riconoscibili, separate da linee di maggior spessore, le unità che disegnano l’ossatura del rilievo (indicate con le sigle ssll e ttpp ed in seguito richiamate anche come “unità di substrato”) e quelle che, invece, lo ammantano in modo isopaco o determinando locali addolcimenti dei pendii e dei dislivelli (indicate con la sigla mm in fig. 4 ed in seguito richiamate anche come “unità di copertura”). il complesso mm, spesso tra gli 8 ed i 10 m, comprende, dall’alto verso il basso: (a) suoli attuali; (b) alluvioni e colluvioni piroclastiche; (c) prodotti in giacitura primaria della eruzione del 79 d.c. sotto questi ultimi si osservano (d) sabbie piroclastiche e cineriti con tetto humificato ed altre tracce di pedogenesi intercalate. esse potrebbero rappresentare più antiche eruzioni pliniane del sommavesuvio, in analogia con quanto segnalato in affioramento da rolandi et al. (1997) presso porta nocera e da mastroroberto (1998) a s. abbondio (vedi capitolo 3). nel basso morfologico che separa la collina della civita dal dosso del cimitero il complesso di copertura poggia su depositi limo-sabbiosi nerastri e pozzolane (e) che sembrano rappresentare un antico riempimento alluvionale. questi depositi appaiono, a loro volta, dissecati e la nuova incisione è riempita dall’unità (d) del complesso di copertura. per quanto concerne il substrato, si osserva che nella parte centrale della sezione (località civita giuliana), la sua parte sommitale è caratterizzata da sabbie sciolte o poco addensate, con lapilli, per lo più di colore rossastro che poggiano in maniera concordante su un’unità a scorie e brandelli lavici immersi in matrice sabbiosa. questa unità fa a sua volta passaggio, per intercalazioni, a sottostanti lave. esse sono descritte generalmente come ricche di fenocristalli, compatte, ma anche con struttura vacuolare. le lave formano due o più colate, inclinate conformemente ai fianchi dell’arco della civita, e mancano nel tratto di sezione a ene del sondaggio cg14. i sondaggi cg22, cg23 e cg64 evidenziano, a letto delle lave, un complesso mai segnalato prima, formato da tufi gialli e grigi a luoghi alterati, sabbie grossolane con pomici e pozzolane (unità ttpp di fig. 4 spessore minimo 20 m circa) la cui base, mai raggiunta, è ad almeno 20 m sotto il livello marino. a nostro avviso, tale complesso potrebbe rappresentare il frutto delle più antiche eruzioni del vulcano pompeiano. esso equivale quasi certamente all’unita tufacea, coperta dalle lave, dei pozzi della casa dei vasi di vetro e porta vesuvio nell’area archeologica pompeiana (po2a-b in fig. 2-3). sia dalla sezione di figura 4 che da altri dati di sottosuolo appare chiaro che il complesso ttpp delinea un antico alto morfologico, al cui andamento si adegua, nel tratto più occidentale della sezione, quello delle colate. nella parte centrale della sezione, invece, le lave immergono in direzione opposta a ttpp, la cui stratificazione continua ad immergere verso occidente anche nel dosso del cimitero. questa uniformità di giacitura consente di interpretare tale dosso come un lembo smembrato dell’arco della civita, piuttosto che come un piccolo edificio a sé. 109 fig. 5 i prodotti del cono di s. abbondio emersi in affioramento lungo l’autostrada napoli-pompei-salerno. the scoria and ejecta of the s. abbondio cone as exposed during the works to enlarge the napoli-pompeii-salerno motorway il “vulcano di pompei”: nuovi dati geomorfologici e stratigrafici 55..22 - ddaattii ssuullllee bboocccchhee eerruuttttiivvee mmiinnoorrii anche per l’area di s. abbondio (fig. 1) sono stati raccolti dati che confermano le ipotesi tracciate su basi geomorfologiche. in particolare, il fatto che questa collinetta sia strettamente collegata ad una locale bocca eruttiva è supportato dai caratteri molto prossimali delle vulcaniti che ne costituiscono l’ossatura, osservate in un taglio effettuato durante i lavori di ampliamento dell’autostrada napoli-pompei-salerno. sono livelli fortemente clinostratificati di scorie schiumose spesso saldate, di colore variabile tra il rossastro ed il nerastro e con frequenti fenocristalli di leucite (fig. 5). vi si rinvengono inglobati sia blocchi rigettati di lave compatte, che giungono fino a diversi decimetri di diametro, sia brandelli di sedimenti marini (limi sabbiosi giallastri poco consolidati) di dimensioni prossime al decimetro. per essere giunti integri alla superficie e per il fatto che recano modesti segni di “cottura”, questi sedimenti sono stati presumibilmente strappati alle formazioni litorali tardo pleistoceniche presenti a poche decine di metri di profondità (capitolo 6 e fig. 3). una provenienza dal complesso versiliano sembra invece da escludersi perché le sabbie litorali oloceniche sono, di norma, nerastre per la grande abbondanza di minerali femici vesuviani. si ricorda, inoltre, che sulla collina di s. abbondio è stata rinvenuta una necropoli dell’età del bronzo con tombe scavate nelle scorie e sepolte poi da prodotti piroclastici attribuiti alla eruzione somma-vesuviana “di avellino” (circa 3,6 ka; mastroroberto, 1998). circa la probabile forma craterica evidenziata nella zona di pompei scavi (“cratere di via stabia”), i dati geologici che avallano questa ipotesi geomorfologica sono in primo luogo le giaciture delle lave leucitiche scoriacee che affiorano nella paleofalesia versiliana. infatti, tra porta marina (inf) e porta di stabia (fig. 6), la lave hanno un’immersione convergente verso il settore ove sorge la casa di giuseppe ii ("h" in fig. 2). a ciò si aggiunge il fatto che il tetto delle lave si deprime verso il centro della forma in questione, come dimostrano i dati emersi dai saggi realizzati nella casa dei postumii2 (viii, 4, 49), nell'area del portico del foro triangolare e nella casa di "giuseppe ii" (viii, 2, 39)3 (rispettivamente "f" "g" "h" in fig. 2). l’analogia tra le lave di porta vesuvio e quelle affioranti, anche in forma più alterata, sotto il foro triangolare e nella “casa di giuseppe ii” era stata già indicata da ippolito (1938). ulteriori dati relativi alla quota del tetto delle lave lungo il margine orientale del cratere si ricavano dai sondaggi eseguiti nell’insula dei casti amanti (ix,12) (patti, 2003) (“l” in fig. 2). lungo il margine settentrionale del cratere le campagne di scavo archeologico, condotte nel 2003 dall’università degli studi di napoli “l’orientale”, sotto la guida del prof. fabrizio pesando, hanno rivelato, nella reg. vi, un paleosuolo di età arcaica (con tracce di frequentazione umana) che marca una paleotopografia inclinata vero n. tale declivio fu mascherato dalle ultime eruzioni protostoriche del somma – vesuvio, da interventi antropici di età classica ed, infine, dall’eruzione del 79 d.c. per ubicazione ed orientazione, questo elemento paleotopografico potrebbe corrispondere alla parte alta del fianco esterno dell’edificio vulcanico di via di stabia, laddove esso si sovrappone all’arco della civita. questo elemento morfologico trova riscontro anche nei saggi di scavo condotti nel 2003 dall’equipe coordinata dal dott. florian seiler (istituto archeologico germanico) a porta vesuvio (“i” in fig. 2). qui sia il tracciato di una strada, preliminarmente ascritta al periodo arcaico, che le sovrastanti strutture collegabili all’acquedotto mostrano una pendenza verso nne. la strada suddetta poggia sui prodotti delle ultime eruzioni protostoriche del somma – vesuvio, che coprono, a loro volta, un paleosuolo con pomici dell’eruzione di “ottaviano” (8 ka) (paola petrosino com. pers.) giacente su lave leucitiche scoriacee. il tetto di queste lave si deprime verso s con un dislivello di circa 5.2 m tra la porta vesuvio ed il pozzo di età classica di porta vesuvio (maiuri 1973), cioè su soli 20m di distanza. il dott. seiler fornisce ulteriori dati interessanti a conferma della ricostruzione mostrata in figura 2 indicando l’esistenza di una pendenza verso via di stabia, quindi verso l’asse nw-se della forma craterica, dei livelli presenti sotto le strutture più antiche messe in luce nei saggi realizzati ad w della strada. 55..33 --mmoorrffoollooggiiaa ddii ssuuppeerrffiiccii ssttrraattiiggrraaffiicchhee sseeppoollttee utilizzando i dati stratigrafici ricavabili da affioramenti, saggi archeologici e perforazioni, abbiamo tentato di ricostruire, almeno nelle linee essenziali e per aree con una certa fittezza di informazioni, la morfologia di alcune superfici stratigrafiche sepolte. in particolare ciò è stato effettuato per il tetto del complesso lavico presente nella collina pompeiana e per quello delle lave individuate nel sottosuolo della pianura. aa)) tteettttoo ddeellllee llaavvee ssuullllaa ccoolllliinnaa ppoommppeeiiaannaa sebbene i dati disponibili abbiano consentito di tracciare solo alcune isoipse (con equidistanze di 5 e 10 m), gli andamenti ottenuti confermano l’esistenza della forma arcuata positiva emersa dall’analisi geomorfologica e da noi denominata “arco della civita”. la ricostruzione del tetto delle lave su tale elemento morfo-vulcani110 fig. 6 affioramenti lavici lungo il margine meridionale dell’area archeologica di pompei. lava outcrops along the southern edge of the archaeological site of pompeii. 2comunicazione verbale del dott. felix pirson, responsabile dello scavo per l’istituto archeologico germanico di roma. 3comunicazione verbale del prof. paolo carafa, responsabile dello scavo per l’università “la sapienza” di roma, e della dott.ssa maria teresa d'alessio. a. cinque & g. irollo co è mostrata in figura 7. verso w e nw, poco fuori dell’area mappata, vi sono altre isolate segnalazioni di prodotti interessanti emersi nei sondaggi realizzati nell’alveo penniniello e lungo la linea torre annunziatapompei della ferrovia circumvesuviana, nei tratti di boscotrecase e boscoreale. si tratta di lave vacuolari e scorie grigio-rosate ritrovate a quote abbastanza congruenti con la paleo topografia di figura 7. i sondaggi realizzati a boscoreale indicano lave con tetto a quote comprese tra 30 e 37 m s.l.m. ed in qualche caso la significativa presenza di minerali secondari fumarolici che ne dimostrano la prossimalità. altre segnalazioni si ricavano dai sondaggi realizzati lungo il tracciato autostradale tra torre annunziata e villa dei misteri (di vito et al., 1998a; sondaggi g5, s17, g6 di fig. 1 e 5 dello stesso lavoro). le isolinee di figura 7 delineano anche l’alto isolato di s. abbondio e la depressione di via di stabia; due forme vulcaniche che trovano conferma e migliore definizione con i dati riportati nel paragrafo 5.2. 111 fig. 7 ricostruzione tentativa del tetto delle lave nell’area dei rilievi di pompei (i punti neri indicano l’ubicazione dei sondaggi utilizzati, le cifre a fianco la quota in m s.l.m. del tetto delle lave). tentative reconstruction of the lavas top surface in the area of pompeii hill (black dots indicate the drilling locations plus elevation data (in meters a.s.l.) of lava top). il “vulcano di pompei”: nuovi dati geomorfologici e stratigrafici per mancanza di sondaggi favorevolmente collocati, non è stato possibile supportare l’ipotesi che la fossa di valle rappresenti una depressione craterica (e/o calderica), come suggerisce la sua posizione e la morfologia del suo fianco occidentale. comunque, se si ipotizza un’antica depressione chiusa, il suo bordo orientale (sepolto da successive fasi aggradazionali della piana) va collocato ad occidente del sondaggio “po5” (fig. 1). infatti se tale sondaggio ricadesse nel perimetro della depressione, risulterebbe difficile spiegare la presenza dei sedimenti marini che il suo log indica tra 64 e -67 m, come pure la totale assenza di lave, che invece affiorano lungo il bordo sw della fossa (presso la porta di sarno, fig. 2) ed immergono verso ne. bb)) tteettttoo ddeellllee llaavvee sseeppoollttee nneellllaa ppiiaannuurraa rocce vulcaniche che, per tipologia e per posizione altimetrica e stratigrafica, potrebbero ascriversi all’edificio pompeiano sono state spesso segnalate in sondaggi effettuati nelle circostanti aree di pianura e di piedimonte vesuviano. molte di queste segnalazioni sono anche riportate nella precedente letteratura (ruggiero, 1879; bakunin, 1907; bassani & galdieri, 1908; luongo & rapolla, 1964; di girolamo, 1969; barra et al., 1989; di vito et al., 1997; 1998a; pescatore et al., 1999). e’ interpretabile come una foam lava anche la “roccia bruciata” segnalata da pescatore et al. (1999) in una serie di sondaggi a nw di porta marina (uniti nella sigla “po178” in fig. 1 e 2). il sondaggio “po4” (fig. 2 e 3), realizzato poco a valle della paleofalesia versiliana, mostra lave con cristalli di leucite e pirosseno augitico di grosse dimensioni, immersi in una massa di fondo vetrosa e vacuolare, ricoperte da depositi litorali del complesso versiliano. nel centro della pompei moderna, la stratigrafia del pozzo che alimenta la fonte salutare (bakunin, 1907; bassani & galdieri, 1908), (“po9” in fig. 1-3) indica prodotti lavici, confrontabili con i termini caratterizzanti le vicine aree di pompei scavi e di s. abbondio, a quote comprese tra -3 e -59 m s.l.m. nel settore ad e e se dei rilievi pompeiani, luongo & rapolla, (1964) segnalano lave sepolte in diversi sondaggi (“po1-5-6-7-8-10-12-13” e “sca11-1415-16-17” fig. 1-3-8). nel sondaggio “po6” ed a palestra grande essi individuano due colate vacuolari sovrapposte: una lava a leucite alterata notevolmente friabile, sovrapposta ad una lava leucitica compatta che nel sondaggio “po6” mostra fenocristalli di leucite non alterati ed una maggiore percentuale di fenocristalli di augite. la lava con leucite alterata è individuata anche nel sondaggio “po8” (s. abbondio) dove ha colore grigio scuro, talvolta rossastro ed aspetto molto scoriaceo; quella leucitica compatta è segnalata anche nel sondaggio “po10”. con la sigla “sca11” abbiamo in realtà indicato una serie di sondaggi ravvicinati che incontrano, sotto il livello leucitico scoriaceo, correlabile alla foam lava dell’area archeologica, una lava compatta non leucitica, priva di fenocristalli e di colore grigio scuro, con sanidino, plagioclasio e pirosseno augitico. utilizzando tutti i dati disponibili abbiamo tentato di ricostruire il tetto delle lave (indistinte), il cui esito è mostrato in fig. 8. dato lo scarso numero di dati e la loro ampia spaziatura, abbiamo preferito tracciare solo poche isolinee, corrispondenti ai valori altimetrici che richiedevano minori estrapolazioni. la morfologia ottenuta non evidenzia nessun marcato alto topografico, arcuato e concavo verso w, che possa interpretarsi come complementare dell’arco della civita. tale situazione suggerisce che le lave sepolte nella parte orientale dell’area di studio si siano messe in posto quando l’edificio testimoniato dall’arco della civita era stato già disturbato da faglie e forse in parte sepolto. d’altra parte, alcune articolazioni altimetriche (tra le quali l’alto morfologico isolato segnalato da di maio & sperandeo (1998), suggeriscono la presenza di più centri di emissione e/o di varie colate indipendenti. la generale pendenza verso se fa invece protendere per una origine somma-vesuviana di almeno alcune delle lave. 66 - ddaattii ee ccoonnssiiddeerraazziioonnii ccrroonnoollooggiicchhee per inquadrare cronologicamente le vulcaniti pompeiane, in mancanza di datazioni dirette, si può far ricorso ai rapporti stratigrafici e geomorfologici che le legano ad altri eventi ed elementi geologici di età nota. in tal senso osserviamo innanzitutto che i livelli scoriacei e lavici del cono secondario di s. abbondio (vedi capitolo 3) sono da ritenere più antichi di circa 3,6 ka, in quanto coperti dalle piroclastiti dell’eruzione “di avellino”. d’altra parte il fianco occidentale della collinetta di s. abbondio sembra essere intaccato dalla paleofalesia versiliana, la quale certamente taglia le lave della collina di pompei scavi (tratto tra porta marina e porta di stabia). tali lave sono quindi da considerarsi anteriori ai paleotrac112 fig. 8 quote del tetto delle lave (in m s.l.m.) nei sondaggi del settore orientale e tentativo di ricostruzione della sua morfologia. si ricorda che nel sondaggio po5 non si hanno lave fino a 65m s.l.m. local values (from drillings) and contour lines describing the top surface of the buried lava flow occurring in the eastern sector of the study area (in metres a.s.l.). note that the drilling po5 reached -65 m a.s.l. without passing any lava body. a. cinque & g. irollo ciati costieri cui corrispondono gli antichi cordoni di bottaro-pioppaino e di messigno, rispettivamente attribuiti agli intervalli 3.6÷2.5 ka e 5.6÷4.5 ka (cinque, 1991). le lave emerse nel saggio archeologico di porta vesuvio (paragrafo 5.2) sono coperte da un paleosuolo che contiene le pomici dell’eruzione di ottaviano per cui risultano più antiche di 8 ka. alcune delle colate laviche che affiorano presso il limite meridionale di pompei antica (zona di porta nocera) sembrano avere più di 19 ka visto che rolandi et al. (1997), analizzando un taglio ora scomparso, vi riconobbero al tetto delle pomici che essi attribuiscono alla eruzione “di sarno” le lave che affiorano lungo il margine sw della collina pompeiana e proseguono nel sottosuolo della antistante pianura, non recano mai in sovrapposizione questo marker. secondo di vito et al. (1998a), alcune delle lave sepolte sarebbero databili a circa 18÷20 ka in quanto, nel sondaggio “po3”, un paleosuolo intercalato alle due colate ha fornito una età radiocarbonio pari a 20.3 ± 0.2 ka, mentre un termine analogo, posto alla base della colata più antica, ha dato una età di 18.7 ± 0.28 ka. riteniamo che questi dati numerici vadano considerati con prudenza, e non solo perché contraddicono l’ordine stratigrafico. in primo luogo si deve osservare che i sedimenti posti tra le due colate e sotto la prima di esse (inclusi tra -14 e -24 m s.l.m.) sono di ambiente transizionale, come confermano le faune di tipo salmastro indicate dagli autori in alcuni livelli. se le datazioni riportate fossero esatte, considerando il livello eustatico di 18÷20 ka, bisognerebbe concludere che questo settore di piana abbia subito un successivo sollevamento di oltre 100 m. tale ipotesi contrasta nettamente con la generale tendenza alla subsidenza che domina nell’area durante il tardo quaternario e non trova riscontro in nessun’altra evidenza geologica o geomorfologica. va quindi presa in considerazione l’ipotesi di un sensibile errore nelle datazioni sopra citate; in particolare un invecchiamento da collegarsi forse alla circolazione di acque molto mineralizzate e ricche di co2 vulcanica, ancora oggi abbondante nelle falde idriche della zona (celico et al., 1998). attribuendo, quindi, a tali datazioni il valore di limiti di età massima e considerando che nella bassa piana del sarno la base del pacco sedimentario versiliano si spinge fino a circa -40 m s.l.m. (cinque, 1991), riteniamo molto probabile che i sedimenti transizionali in questione (e le lave pompeiane che vi si intercalano) risalgano ai primi millenni dell’olocene, inserendosi nella parte mediana di quella successione versiliana cui certamente appartengono i depositi immediatamente post-lave nello stesso sondaggio “po3”. dunque, se questa nostra elaborazione è corretta, l’attività del complesso edificio pompeiano si sarebbe protratta sino a pochi millenni or sono. per attribuire un limite di età massima all’intero edificio pompeiano possiamo poi considerare i depositi marini dei sondaggi “po9” e “po5” (fig. 1-3) compresi tra –64 e –83 m s.l.m. i quali indicano un’ingressione che ben difficilmente avrebbe raggiunto quei luoghi se fosse già stato presente l’apparato vulcanico in questione. essi rilevano un’ingressione marina che si addentra circa 25 km oltre il limite della piattaforma continentale (dove sono stati riconosciuti i cunei di lst del pleistocene medio e superiore; milia & torrente, 1999), per cui vanno quasi certamente legati ad un periodo di marcato high stand. tale periodo va ricercato nel pleistocene ed, in particolare, in epoca anteriore ai 39 ka, in quanto i sedimenti litorali in questione, nel sondaggio “po5” sono sottoposti a una unità tufacea che, per caratteri e posizione altimetrica, sembra essere l’ignimbrite campana. nella piana del sarno, l’ingressione eustatica dell’ois 7 si spinse circa 12 km più all’interno di pompei, raggiungendo il piede dei monti di sarno (spiagge con tetto a -35m s.l.m. nel sondaggio ssml6 di aprile & toccaceli 2002) mentre le paleolinee di riva dell’ultimo interglaciale si spinsero fino a 10 km più all’interno di pompei (depositi di spiaggia e transizionali nel sottosuolo di s. mauro, con tetto a -23m s.l.m.; barra et al., 1991). durante questi ultimi episodi di massimo eustatico, l’area di pompei dovette ricevere sedimentazione pelitica di piattaforma, mentre i sedimenti tra–64 e –83 m nei sondaggi “po9” e “po5” sono delle sabbie e ghiaie litorali che vanno pertanto ascritte a fasi regressive dell’ois 5 o al picco trasgressivo eustatico dell’ois 3.3 (quando, secondo alessio et al. (1994), il mare raggiunge i -18/-20 m s.l.m.). ovviamente i sedimenti in questione sono ribassati dalla ben nota subsidenza quaternaria della piana. volendo ricavare ulteriori vincoli cronologici dai rapporti tra edificio pompeiano ed ignimbrite campana (i. c.), ci si scontra con la difficoltà che essa non è mai segnalata esplicitamente nei log stratigrafici raccolti. tuttavia alcuni di essi segnalano dei tufi grigi e giallastri più o meno litoidi, ovvero degli spessi intervalli di “sabbie piroclastiche” e/o “pozzolane con pomici”, che in prima ipotesi possono interpretarsi come i c. rispettivamente in facies litoide ed in facies sciolta. ma nelle vicinanze della collina pompeiana sono segnalate, con terminologie non dissimili, anche delle piroclastiti che, per quota e gradiente, sono invece da ascriversi alle prime fasi di attività del vulcano locale. 113 fig. 9 ricostruzione della morfologia del tetto dell’ignimbrite campana nel settore orientale e dei prodotti piroclastici pompeiani. (i valori delle isoipse sono in m s.l.m.). tentative reconstruction of the buried top surface of the campanian ignimbrite and other tuffaceous materials belongin to the pompeii volcano. (contour line values are in m a.s.l.). il “vulcano di pompei”: nuovi dati geomorfologici e stratigrafici una ricostruzione del tetto di queste potenti unità piroclastiche è mostrata in figura 9. all’esterno dell’edificio pompeiano la morfologia del tetto della presunta i. c. mostra articolazioni che ben si accordano, per quote e per andamento, con il tetto dell’i. c. ricostruito da aprile & toccaceli, (2002) per la media ed alta piana del sarno. sia in detta figura 9 che nella figura 3 dei citati autori si nota una forma valliva che disseca l’ignimbrite campana e che giunge a quote di circa -30 m nella zona di pompei. la formazione di questa paleovalle è stata certamente favorita anche da bassi livelli glacioeustatici, ma essa si giustifica soprattutto con l’ondata di erosione regressiva innescatasi sul “gradino” creato, sul plateau ignimbritico, dalla faglia nw-se che ribassa l’area del golfo di castellammare di stabia subito dopo (forse anche durante) l’eruzione della i.c. (cinque et al., 1997; milia, 1998; milia & torrente, 1999). il tentativo mostrato in figura 9 purtroppo non consente di comprendere, per mancanza di punti di controllo nelle zone cruciali, se l’edificio tufaceo pompeiano sia cresciuto quando la valle era già incisa o se, predatandola, sia stato da questa dissecato. tuttavia, il fatto che l’edificio dà luogo ad un brusco restringimento della paleovalle tende ad avvalorare maggiormente la prima ipotesi. passando ai dati stratigrafici, sembra che nel sondaggio “po5” le piroclastiti pompeiane poggino sull’i. c. infatti il tufo che qui si riconosce tra –17 e –31 m s.l.m. è correlabile all’i. c. per i suoi caratteri litologici e per la sua posizione altimetrica ben compatibile con la ricostruzione di aprile & toccaceli (2002). ad esso seguono delle “sabbie” anche grossolane (a nostro avviso di natura piroclastica) che plausibilmente rappresentano i primi prodotti del vulcano pompeiano in questa zona. analoghi rapporti di sovrapposizione dei prodotti pompeiani sull’i. c. sembrano riconoscersi, inoltre, nei sondaggi “sca 11-15-17” di figura 3, ubicati all’esterno dell’arco della civita. l’assenza dei depositi ignimbritici nel sondaggio “po9” potrebbe ascriversi a totale elisione durante la sopra citata fase di incisione tardo-pleistocenica (il foro cade infatti nell’asse della paleovalle sepolta). rimane problematica la interpretazione delle pozzolane rossicce, con alternate lave, che si trovano tra –32 e –59 m nel sondaggio “po9”. sebbene litologicamente simili ad alcuni prodotti emessi dalle bocche pompeiane dopo la fase eruttiva a tufi e piroclastiti sciolte, esse si collocano troppo in profondità; persino più in basso della paleovalle prima discussa. potrebbe trattarsi di antichi prodotti del somma o di vulcaniti legate a un centro locale sensibilmente più antico di quelli presi in esame col presente articolo. 88 - ccoonncclluussiioonnii l’esame complessivo dei dati raccolti delinea nell’area di pompei l’esistenza di un complesso vulcanico che trova espressione morfologica nella collina arcuata che da sette termini, presso boscoreale, si allunga fino all’area archeologica della pompei antica (“arco della civita”), nonché nelle culminazioni topografiche minori individuate poco ad e e se di essa. la motivazione geologico-strutturale di questo complesso vulcanico e della sua ubicazione è da riconoscersi, plausibilmente, in un importante lineamento tettonico profondo che è ben evidenziato sulle carte gravimetriche della letteratura (cassano & la torre, 1987): si tratta della faglia ad andamento e-w che va da nocera inferiore (dove definisce un tratto del fronte n dei monti lattari) fino a torre annunziata. essa ribassa il substrato della piana (unità mesozoico-terziarie della catena) di circa mille metri verso n, costituendo uno di principali elementi che definiscono la porzione meridionale del graben della piana campana. l’edificio pompeiano potrebbe collocarsi all’intersezione di tale faglia diretta con un lineamento di direzione appenninica o con una frattura radiale del somma. la ricostruzione dell’andamento nel sottosuolo delle formazioni vulcaniche pompeiane, particolarmente dettagliata nell’area della sezione di figura 4, ha consentito di evidenziare l’esistenza di un complesso basale prevalentemente piroclastico, fagliato ed eroso, che indica un’attività iniziale di tipo sostanzialmente esplosivo. l’attività più recente del complesso vulcanico pompeiano è data invece da emissioni laviche ed attività stromboliana (con prodotti del tipo foam lava). anche se i dati disponibili sono ancora troppo scarsi per chiarire definitivamente la questione, appare verosimile supporre che le lave siano riconducibili a più punti di emissione, alcuni dei quali periferici all’arco della civita (cratere di via stabia; cono di s. abbondio) ed altri ubicati probabilmente su fessure anulari più o meno coassiali col primitivo edificio piroclastico. circa l’età di queste emissioni laviche e scoriacee, il riesame di tutti i dati esistenti ci induce a concludere che esse hanno età variabile da zona a zona e coprono un intervallo di tempo che va da oltre 19 ka (lave presso la porta nocera) fino all’olocene antico. parte di queste emissioni vulcaniche si diressero verso il solco vallivo scavato dal sarno sulla piana dopo che quest’ultima era stata aggradata dalla ignimbrite campana. esse si intercalarono, quindi, ai sedimenti alluvionali, transizionali e costieri che stavano rapidamente colmando la valle durante la fase finale della trasgressione versiliana. con l’apice di questo evento glacio eustatico, il margine meridionale della collina pompeiana venne, infine, modellato da una falesia successivamente disattivata con le fasi di progradazione della piana degli ultimi 5 ka circa. sebbene alcuni dati stratigrafici e paleomorfologici suggeriscano che l’intero edificio pompeiano sia posteriore alla ignimbrite campana, non si può ancora escludere del tutto che quest’ultima predati solo la fase delle emissioni laviche e stromboliane del complesso vulcanico pompeiano, risultando invece più giovane se non coeva all’attività di più spiccato tenore esplosivo. in ogni caso, l’intero edificio pompeiano poggia su sedimenti di pianura costiera e litorali che, sebbene non datati, possono ascriversi ad una trasgressione glacio – eustatica non più antica dell’ ois 5. rriinnggrraazziiaammeennttii si ringrazia il soprintente archeologo di pompei prof. p. g. guzzo per aver autorizzato lo studio delle sezioni emerse nel perimetro dell’area archeologica, per aver consentito di prelevare campioni di lava e per aver 114 a. cinque & g. irollo permesso l’uso delle stratigrafie di sondaggio disponibili in archivio. l’autorità di bacino regionale sarno per aver fornito numerose stratigrafie da sondaggio ed i responsabili delle missioni di scavo archeologico citate nel testo (prof. p. carafa, prof. f. pesando, dott. f. pirson, dott. f. seiler) per aver fornito dati inediti e per le interessanti discussioni. siamo inoltre grati al prof. m. bugno (università degli studi di napoli federico ii) per le indicazioni filologiche relative ai passi degli autori classici citati, al prof. f. senatore per le indicazioni in merito all’area archeologica di pompei ed alla dott. ssa p. petrosino (università degli studi di napoli federico ii) per il prezioso aiuto fornito nell’identificazione delle vulcaniti sia nelle stratigrafie da sondaggio che sui campioni. ringraziamo, infine, il dott. a. sposato e l’altro referee anonimo della rivista per averci fornito preziosi consigli su come migliorare la stesura finale del testo. bbiibblliiooggrraaffiiaa alessio m., allegri l., antonioli f., belluominii g., improta s., manfra l. & preite martinez m. 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(2003) – tectonic controls on the genesis of ignimbrites from the campanian volcanic zone, southern italy – mineral petrol., 7799, 3-31. romano p., santo a. & voltaggio m. (1994) l’evoluzione geomorfologica della pianura del fiume volturno (campania) durante il tardo quaternario (pleistocene medio-superiore – olocene) – il quaternario, 77 (1), 41-56. rosi m. & sbrana a a. (a cura di) (1987) the phlegrean fields. cnr quad. ric. sci.roma, 111144 (9). ruggiero m. (1879) della eruzione del vesuvio nell’anno lxxix, godot, napoli, 5-6. scandone r., bellucci f., lirer l. & rolandi g.(1991) the structure of the campanian plain and the activity of the neapolitan volcanoes (italy) – j. volcanol. geotherm. res. 4488, 1-31. vitruvius – de architectura – f. krohn, lipsiae 1912. 116 ms. ricevuto il 28 ottobre 2003 testo definitivo ricevuto il 6 aprile 2004 ms. received: october 28, 2003 final text received: april 6, 2004 a. cinque & g. irollo imp.giordano tthhee sseeddiimmeennttaattiioonn aalloonngg tthhee rroommaann ccooaasstt bbeettwweeeenn mmiiddddllee aanndd uuppppeerr pplleeiissttoocceennee:: tthhee iinntteerrppllaayy ooff eeuussttaattiissmm,, tteeccttoonniiccss aanndd vvoollccaanniissmm –– nneeww ddaattaa aanndd rreevviieeww gguuiiddoo ggiioorrddaannoo11,, aalleessssaannddrraa eessppoossiittoo22,, ddoonnaatteellllaa ddee rriittaa11,, mmaarriinnaa ffaabbbbrrii11,, iillaarriiaa mmaazzzziinnii11,, aalleessssaannddrraa ttrriiggaarrii11,, ccaarrlloo rroossaa11 && rreennaattoo ffuunniicciieelllloo11 1dipartimento scienze geologiche università degli studi “roma tre” 2istituto nazionale di geofisica e vulcanologia, roma abstract the quaternary stratigraphy of the roman coastal area is one of the most studied for the excellent exposures of the sedimentary succession, which offer the opportunity to analyse the interplay between eustatism, tectonics and volcanism. we present an updated interpretation based on new stratigraphic and geomorphologic data. sedimentary successions have been organised as unconformity-bounded stratigraphic units, based on the hierarchy of the bounding unconformities. major regional unconformities are related to eustatic sea level changes and regional uplift, whereas tectonic uplift and subsidence produced high relief but localised unconformities. major regional unconformities are related to eustatic sea level changes and regional uplift, whereas tectonic uplift and subsidence produced high relief but localised unconformities. the sedimentary record is best preserved during high stands of the sea level, as constrained by the several available age determinations of volcanic deposits. the transition from marine to continental environments occurred between approximately 850 and 700 ka, when the roman area hosted the deltaic sedimentation from a paleo-tiber river (ponte galeria synthem). the uplift of the nw-trending mt. mario rise, isolated the deltaic sedimentary wedge and forced the paleo-tiber toward the se, inside a subsiding valley wherein a thick succession of fluvial conglomerates was deposited. as a consequence of the river diversion, a large lake or swamp probably developed in the area, bearing an influence upon the early phreatoplinian activity of the colli albani volcano which started at about 600 ka (santa cecilia synthem; ca. 700-550 ka). the growth of the volcano progressively shifted the river back northward, across the monte mario rise (after ca. 550 ka) approximately where the present day river has its course. the valle giulia synthem (ca. 550-450 ka) is made up of clastic and volcaniclastic fluvial deposits, as well as travertine related to both active tectonics (up to 20 m of local uplift) and hydrothermal activity. the subsequent torrino synthem (ca. 450-350 ka) is mostly made up of large volume ignimbrites and lavas erupted both from the colli albani volcano to the s and the sabatini volcanoes to the n. regional and local tectonics was relatively quiescent. this synthem is cut by the erosional unconformity formed during the low stand of the sea level relative to the oxygen isotopic stage 10. the overlying succession has been named quartaccio synthem, characterised at the base by the villa senni eruption unit (ca. 350 ka), a complex ignimbrite succession erupted from the colli albani volcano, which caused the last and largest collapse of its caldera. the following rise of the sea level produced an abrasion surface at the top of the ignimbrite overlain by dune sand (nuova california subsynthem, i.e. duna rossa antica auct.). these deposits are cut by ne-trending faults between pomezia and castelporziano and uplifted by 140+/-5 m during ca. 70 ka, at the rate of 2 mm/y. the uplift produced a local high relief unconformity wherein the aurelia and the vitinia subsynthems were deposited until ca. 280 ka. the top of the quartaccio synthem is presently at elevations comprised between 40 m and 60 m a.s.l. successively, along with the waning of the volcanic activity, regional uplift resumed at a rate of approximately 0.2 mm/y. this allowed the preservation of terraced deposits, along the coastal belt both to the n and s of the tiber delta and along the tiber valley, referred to two different isotopic stages. those related to the oxygen isotopic stage 7 (campo selva synthem), are today preserved between 30 and 40 m a.s.l. whereas those related to the oxygen isotopic stage 5 (saccopastore synthem), occur between 15 and 30 m a.s.l. the computed regional uplift rate is well in agreement with known data for the tyrrhenian terrace along the italian coast. riassunto il litorale romano è uno degli ambienti più studiati per capire le relazioni tra tettonica, vulcanismo ed eustatismo nel corso del pleistocene. questo lavoro propone una nuova sintesi delle complesse relazioni stratigrafiche e geomorfologiche di quest’area. i corpi rocciosi sono stati organizzati in unità stratigrafiche a limiti inconformi, in base alla gerarchia delle superfici che li delimitano. per il pleistocene medio-superiore dell'area romana, le superfici di grado gerarchico maggiore e correlabili a scala regionale, sono legate alle variazioni eustatiche del livello marino, mentre l'azione della tettonica sviluppa superfici ad alto rilievo ma localizzate alle aree di deformazione. le successioni sedimentarie sono da correlare, in genere, agli alti stazionamenti del livello del mare, come suggerito dalle datazioni dei livelli vulcanici intercalati. l’emersione dell’area romana avviene con la deposizione, tra la dorsale di m. mario e la costa, dell’unità di ponte galeria (ca. 850-700 ka) in facies di delta, alimentata da un paleotevere proveniente da n. l’isolamento di questo cuneo deposizionale avviene per l’innalzamento dell’alto di m. mario a direzione nw-se. il tevere è forzato a scorrere ad est di questo cuneo, parallelamente alla costa verso se, lungo una fascia in continua subsidenza con la deposizione di diverse decine di metri di conglomerati, probabilmente determinando una vasta area palustre che condizionerà il carattere freatomagmatico delle prime eruzioni dei colli albani, note come tufi pisolitici. queste unità costituiscono il sintema santa cecilia, depostosi tra 700 e 550 ka ovvero tra lo stadio 17 ed il 15. a partire da questo momento, la crescita del vulcano dei colli albani risospinge il tevere verso nord dove trova un varco verso la costa vicino al suo corso attuale. il successivo sintema valle giulia (stadio 13) accoglie, oltre alla sedimentazione del tevere e quella vulcanoclastica, anche ingenti volumi di travertini a testimonianza di una tettonica attiva con dislocazioni dell’ordine dei 20 m, e di un importante sistema idrotermale legato all’inizio del vulcanismo. nel successivo sintema torrino (stadio 11) sono inclusi i maggiori volumi di prodotti vulcanici, con la messa in posto di vaste coltri ignimbritiche ed espandimenti lavici sia dai colli albani (lave di vallerano, pozzolane rosse, lave di fosso tre rami, pozzolane nere) che dai vulcani sabatini (tufo rosso a scorie nere). durante questo periodo la tettonica regionale è relativamente quiescente. il sintema è tagliato dalla superficie relativa all’abbassamento del livello del mare, durante lo stadio 10, entro cui si depone il sintema aurelia, con alla base l’unità ignimbritica del villa senni (350 ka), cui si deve il collasso della caldera tuscolano-artemisia al centro dei colli albani. subito dopo la messa in posto del villa senni si ha l’ingressione marina relativa allo stadio 9 che porta alla formazione di una superficie di abrasione al tetto dell’ignimbrite, coperta da sabbie di spiaggia, duna e retroduna (subsintema nuova california), ovvero la duna rossa antica auct. questa superficie è dislocata da faglie ad andamento ne tra pomezia e castelporziano ed oggi si trova a quote comprese tra +60 m s.l.m.e +100 m s.l.m. il sollevamento determina la formazione di una superficie erosiva tra la costa e la bassa valle del tevere, che ospiterà fino ai 280 ka la deposiil quaternario italian journal of quaternary sciences 1166(1bis), 2003, 121-129 122 c. giordano et al. 11.. iinnttrroodduuccttiioonn the roman coastal area extends between the sabatini volcanoes to the north and the colli albani volcano to the south, along the tyrrhenian coast of central italy (fig. 1). excellent exposures of quaternary sedimentary successions occur in the area and offer the opportunity to analyse the interplay between eustatism, tectonics and volcanism. since the early fifties, many different interpretations have been proposed on the number and significance of the sedimentary successions, based each time on new exposures and new age determinations. table 1 is a synoptic scheme of the main stratigraphic interpretations. open questions concern the hierarchy of the unconformities and their relationship to glacial periods (blanc, 1957; ambrosetti & bonadonna, 1967; manfredini, 1990; karner & renne, 1998; karner et al., 2001a, b), and the internal architecture of the sedimentary successions in relationship with sea level changes and tectonic uplift (e.g., conato et al., 1980; malatesta & zarlenga, 1986; milli, 1997). some workers have pointed out the contribution of volcanism to sedimentary processes (e.g. cavinato et al., 1992; marra & rosa, 1995), while others analysed the geometry of coastal terraces related to the pleistocene sea level oscillations (e.g. basili & bosi,1996). several faunal units have been based on the well preserved vertebrate fossil remains occurring within the pleistocene roman sedimentary successions and, together with archeological findings, they have been used for detailed paleoenvironmental reconstructions (cavarretta et al. 2001 and references therein). this paper focuses on the middle to upper pleistocene sedimentary succession of the roman area and syntethises data from more than two thousand stratigraphic sections, measured in an area of approximately 1500 km2. the proposed hierarchy of the unconformities is based on their lateral extension and morphologic relief, and on the facies associations of the enclosed rock bodies. 22.. mmeetthhooddoollooggyy starting from 0.6 ma, the roman coastal area has received volcaniclastic sedimentation from the two volcanic areas of the sabatini to the north and of the colli albani to the south. the presence of volcaniclastic deposits transitional to volcanic deposits and to coastal sediments has allowed the correlation of volcanic activity and coastal sedimentation and the understanding of how volcanism, eustatism and tectonics acted in the evolution of the area. some of the large erupted volume pyroclastic flows reached the coastal area and the deposits are interbedded with the coastal sediments. the geochronologically dated volcanic units have been used to constrain the time range of deposition of the hosting sedimentary successions. lithostratigraphic units have been organised as unconformity -bounded stratigraphic units (ubsu). the most widespread erosional surfaces in the roman area during middle to upper pleistocene are related to the low stands of the sea level. these unconformities bound the synthems, i.e. the fundamental ubsu in respect to which the hierarchy of the other unconformities is referred (salvador, 1987). vertical tectonic displacements may locally enhance or reduce the field evidence of unconformities. the correlation of the synthem to glacio-eustatic variations of the sea level is important, as the hierarchy of unconformities is referred to a geological process. each recognised synthem has been correlated to the oxygen isotope scale (pisias et al.1994; shackleton 2000) on the basis of available geochronological and /or paleontological data. lateral facies relationships between volcanic units and volcaniclastic sediments have allowed the distinction of syn-eruption and inter-eruption successions related to the volcanic activity of the colli albani and of the sabatini volcanoes (cf. smith, 1987; giordano et al., 2002a). where historical formational or unit names are not misleading, we have retained the traditional name for the synthem (for example our ponte galeria synthem coincides with the ponte galeria formation auct.), whereas we have changed it where names may induce confusion (for example the s. cosimato formation auct. has been interpreted in many different ways, and means different things to different authors.). 33.. mmiiddddllee ttoo uuppppeerr pplleeiissttoocceennee,, ssttrraattiiggrraapphhiicc aanndd tteeccttoonniicc eevvoolluuttiioonn ooff tthhee rroommaann aarreeaa the transition from marine to continental environments in the roman area occurred with the deposition of the ponte galeria synthem between approximately 850 and 700 ka (cf. the ponte galeria formation by conato et al., 1980;. table 1). the ponte galeria synthem represents the sedimentation of a paleo-tiber river delta (e.g. marra & rosa, 1995; milli, 1997) fed from the north. the deposits of this unit are described in a number of papers (table 1) and range from fluvial conglomerate and sand to lagoonal clay and beach sand and gravel. the ponte galeria synthem encomzione dei subsintemi aurelia e vitinia la cui quota di tetto è compresa tra i 40 m ed i 60 m s.l.m. questo terrazzo sutura, o quasi, le dislocazioni tra pomezia e castelporziano, che dunque determinarono un innalzamento relativo di 140+/-5 m in circa 70 ka, al tasso di circa 2 mm/a. successivamente la regione va incontro a sollevamento generalizzato che, in concomitanza con le oscillazioni del mare, ha consentito la conservazione di terrazzi incassati sia lungo la costa che lungo la valle del tevere, dove i sedimenti relativi allo stadio 7 formano il sintema campo selva oggi posti tra 30 m e 40 m s.l.m., mentre i depositi relativi allo stadio 5 formano il sintema saccopastore, oggi riconoscibili tra quota 15 m e 30 m s.l.m. il tasso calcolato regionale di sollevamento è di 0.2 mm/a in accordo con quanto noto per il litorale laziale a nord ed i dati noti del tirreniano. key-words: sedimentation, volcanism, tectonics, eustatism, quaternary parole chiave:, sedimentazione, vulcanismo, tettonica, eustatismo, quaternario passes several sea level oscillations (at least from stage 20 to stage 17; marra et al., 1998), although compensated by subsidence. the synthem forms an aggradational wedge up to 80 m thick. between ca. 700 and 600 ka, the uplift of the nw-trending mt. mario rise tilted the block by few degrees toward the w-sw, and caused the diversion of the paleo-tiber river toward the southeast (giordano et al., 2002b), along the crescenzatorrenova paleovalley (fig. 1). the former ponte galeria delta was therefore isolated from the river system and formed a plateau sloping toward the sea (fig. 1). as a consequence of the uplift, a high relief erosion surface formed, preserved today to the w and the s of the plateau. the unconformity is mostly represented by v-shaped paleo-gullies. the overlying sedimentary succession is made up by an aggradational and fining upward succession of fluvial to lacustrine sediments, mainly derived from the underlying ponte galeria synthem, with increasing upward volcaniclastic sediments derived from the early explosive eruptions from the sabatini and colli albani volcanoes. this succession is named “s.cecilia synthem” (cf. marra & rosa, 1995) and can be correlated with the isotopic stage 15 (fig. 1), on the basis of interbedded ignimbrites dated between 561+-1 ka and 548 + 4 ka (karner et al., 2001b). the largest of those volcanic deposits are the trigoria eruption unit and the tor de cenci eruption unit from colli albani (de rita et al., 2002a), and the tufo giallo della via tiberina eruption unit from the sabatini (de rita et al., 1993; karner et al. 2001a). the mt. mario rise prevented ignimbrites from the sabatini volcanoes (namely the tufo giallo della via tiberina) to reach the area to the south and west of rome, and diverted the pyroclastic flows along the paleo-tiber river, where the ignimbrites occur with remarkable thickness. the river diversion gave also rise to lacustrine environments, influencing the phreatomagmatic character of the early volcanic activity of the colli albani volcano (de rita 123the sedimentation along the roman coast ... figure 1 dem of the study area (courtesy of esrin) and schematic interpretation of the main structural, volcanic and geomorphologic features (see text for explanation). 124 et al., 2002a). the lowest elevation of the basal unconformity of the santa cecilia synthem occurs at 18 m a.s.l. in the ponte galeria area where the succession is maximum 32 m thick in outcrop. the same unconformity is located at – 80 m in respect to sea level (r.s.l.) to the east of the mt. mario rise, where the succession is more than 45 m thick, as inferred from borehole data. these data indicate that vertical tectonic displacements occurred during and after the deposition of the santa cecilia synthem. the growth of the colli albani volcano caused the progressive shift of the paleo-tiber back northward, where the river crossed the mt. mario rise in a position similar to present day. from then onwards, all river terraces relative to the following aggradational periods are found both along the right and the left river banks of the present course of the tiber river, testifying that little shifts have occurred ever since. the following synthem, named “valle giulia” (cf. marra and rosa, 1995), comprises an aggradational and fining upward succession of fluvial deposits, volcanic units and several travertine plates, related to the presence of hydrothermal system. the thickness of the fluvial succession is up to 30 m. the most widespread volcanic units present within this synthem, the palatino phreatomagmatic unit, the casale del cavaliere eruption unit (de rita et al., 2002a) and the tufo giallo di prima porta (karner et al., 2001b) are dated at around 528+-1 table 1 comparison between the stratigraphy proposed in this paper and previous interpretations. and 514+-3 ka (karner et al., 2001b), which constrain the synthem to the isotopic stage 13 (table 1). the lowest elevation of the basal unconformity of the valle giulia synthem is presently at approximately 10 m a.s.l., whereas it is downthrown by some tens of metres to the east of the mt mario rise. vertical tectonic displacements during and after the valle giulia emplacement determined the development of subsiding sectors mostly along ne-trending and nw-trending faults. the successive synthem, named “torrino” encompasses an aggradational and fining upward succession of mostly volcaniclastic sediments and volcanic deposits relative to large lava flows (vallerano lava flows; fosso tre rami lava flows; cf. de rita et al., 1995) and large volume, caldera forming explosive eruptions (pozzolane rosse and pozzolane nere eruption units) from the colli albani, as well as from the sabatini (tufo rosso a scorie nere eruption unit). this synthem is constrained at the stages 12 and 11 (tab. 1), on account of the available age determinations on the volcanic units which span from the 460+-4 ka for the vallerano lava flow at the base of the synthem, to the 407+-4 ka for the pozzolane nere at the top (data from karner et al., 2001b to be compared with voltaggio and barbieri, 1995 and reference therein). the basal unconformity of this synthem is today at 10 m a.s.l., and the maximum thickness in outcrop of the fluvial succession is 30 m. the synthem does not appear to record the occurc. giordano et al. 125 rence of important vertical tectonic displacements. the torrino synthem is cut by an erosion surface which is the basal unconformity of the successive synthem, named “quartaccio”. the formation of the erosion surface is chronologically well constrained at the low stand of stage 10 by the presence on top of the surface of the large volume and caldera-forming tufo lionato-villa senni ignimbrites from the colli albani. these ignimbrites have been dated several times with different techniques at around 350 ka (e.g. bernardi et al., 1982; radicati di brozolo et al., 1981; karner and renne, 1998). the tufo lionato-villa senni (tl-vs) ignimbrites locally rest on beach-sand and marine sediments (nuova california unit) which record the sea level at ca. 350 ka (fig. 2), evaluated, according to wealbroeck et al. (2002), at –120 m r.s.l. (cfr. fig. 4). in the pomezia-castelporziano area, several sedimentary units at different elevations are related to the subsequent marine ingression relative to the isotopic stage 9. this probably records the contemporaneous uplift of the pomezia-castelporziano rise with respect to the ardea-basin along ne-trending faults (figs. 1, 2 and 3). in this area, an abrasion surface at the top of the tlvs ignimbrites, is covered by dunalto retro-dunal-sand (the castelporziano unit; i.e. “duna rossa antica” or “older dune” auct.), which is presently uplifted to up to 100 m a.s.l. (figs. 2 and 3), and which can be related to any moment between the low stand 10 and the following high stand 9. the uplift isolated the pomeziacastelporziano block, against which the aurelia unit was deposited. the aurelia unit forms a fluvial to marine terrace, presently visible along the tiber river valley (figs. 1, 2 and 3). the lowest elevation of the basal unconformity of the aurelia unit is at 10 m a.s.l. whereas the top reaches 50 m a.s.l. the aurelia unit is generally overlain by the vitinia unit, a sedimentary aggradational succession, rich in volcaniclastic sediments mostly derived from the contemporaneous activity of the faete epoch of the colli albani volcano (ca 350-270 ka; de rita et al., 1995). the aurelia and the vitinia units are separated by a low relief unconformity surface, which never cuts lower than the aurelia basal unconformity (fig. 2), and which outcrops at 30 m a.s.l. at the lowest. the top of the vitinia unit reaches 55-60 m. at the top of the vitinia unit, the scatter presence of a pumice fallout deposit related with the tufo giallo di sacrofano from the sabatini volcanoes (de rita et al., 1993) dated at 285+-1 (karner et al., 2001b), constrains the vitinia unit to the stage 8.5, i.e. a secondary warm peak occurred during the cooling that led to the low stand relative to the isotopic stage 8 (fig. 4 and table 1). the 55-60 m surface, which corresponds to the top of the vitinia unit can also be recognised along the seaside margin, facing west, as a continuous surface which sutures the displacements of the pomezia-castelporziano high. this surface constrains the pomeziacastelporziano uplift to a time span comprised between the deposition of the tlvs ignimbrites (at 350 ka) and the vitinia unit (at 280 ka) (figs. 1, 2 and 3). the more recent terraces are preserved at progressively lower elevations (figs. 1 and 3) indicating that regional uplift re-started after the deposition of the vitinia unit at the top of the quartaccio synthem. two marine terraces are preserved along the coast at 30-40 m a.s.l. (“campo selva” synthem) and 15-30 m a.s.l. respectively (saccopastore” synthem) (fig. 3). the sediments relative to the campo selva synthem are visible in a number of quarries (e.g. tacconi quarry) but bear no datable volcanics or fossils, so that the age constrain is not well defined although it appears logical to figure 2 stratigraphy and geomorphology of the quartaccio synthem across the pomezia-castelporziano high and the tiber river valley (see fig. 1). the tufo lionato ignimbrite emplaced at sea level over wet marineto beach-sediments, at 350 ka, during the low stand 10 of the sea level, and was then overlain by dune sand before it was uplifted to form the erosion surface (dashed line) inside which the aurelia and vitinia subsynthems are infilled. the sedimentation along the roman coast ... 126 relate it to the stage 7. along the tiber river no fluvial terrace that can be safely correlated with this stage. the age of the saccopastore synthem, the lowest terrace (figs. 1 and 3), is constrained at the stage 5a by the presence of strombus bubonius fauna reported by blanc (1936) from the north of the tiber river (casal di statua, 19 m a.s.l.). in the city of rome, along the course of the tiber river, several fluvial terraces occurring at an average elevation of 35 m a.s.l, can be related to this stage. in this deposits the “man of saccopastore”, a neanderthal man dated at about 100 ka, was found (blanc, 1942). 44.. ddiissccuussssiioonn aanndd ccoonncclluussiioonnss regional uplift, local tectonics, eustatism and volcanism, acted during the middle to upper pleistocene geologic evolution of the roman area. the correlation of the basal unconformity of synthems to periods of low standing of the sea level has, as constrained by tephrachonologic data, allowed the evaluation of the relative role of regional uplift versus local tectonics. in table 2 we have computed the amount and the rate of vertical uplift for several stratigraphic surfaces. the error bar for each computed value, is given by the maximum and minimum elevations of the top or the base of the terrace, on the time span of deposition. this time span is taken conservatively to encompass the peaks of the oxygen isotopic stage on the curve of waelbroek et al., (2002). the present day elevation of the top of the marine terraces related to the stages 5a (15-30 m a.s.l. for the saccopastore synthem), 7 (35-45 m a.s.l. for the campo selva synthem) and 9-8.5 (55-60 m a.s.l. for the quartaccio synthem) are similar along the whole roman coast, both to the north and to the south of the tiber river delta and therefore are related to regional uplift. the computed uplift rate averages at 0,2 mm/y, and appears to be constant since the vitinia unit emplacement, i.e. approximately since 280 ka (tab. 2 and fig. 4). this value is well comparable with the regional uplift rate computed for the 125 ka marine terrace by bordoni and valensise (1998), as well as with stratigraphic and geomorphologic data from the coast of northern latium, where, similarly, three orders of terraces related to stages 9, 7 and 5 are present at comparable elevations (de rita et al., 2002b). it must be underlined that similar values are also known from geoarchaeological studies of roman times remains (anzidei et al., 2002). on the contrary, the uplift of the pomeziacastelporziano high along ne-trending faults, which most likely re-activated the pliocene-lower pleistocene masterfaults of the adjacent ardea basin (faccenna et al., 1994) (fig. 1 and fig. 3) is a localised tectonic process, that occurred shortly after the eruption of the tufo lionato-villa senni ignimbrites and the collapse of the colli albani caldera at 350 ka. the computed uplift rate is high, at 2 mm/y, which implies a fast and discrete event, possibly related to volcano-tectonic processes. today, the area is still affected by intense hydrothermal activity (e.g. chiodini & frondini, 2001; quattrocchi et al., 2001) aligned along the main ne-trending faults. the older santa cecilia synthem (stage 15), valle giulia synthem (stage 13) and torrino synthem (stage 11), do not show important intervening regional uplift, except for localised mto 10 m-scale faulting. taking into consideration that the deposition of the three synthems hosted the largest volume of erupted products figure 3 block diagram of the pomezia-castelporziano high illustrating the geometric relationships among terraces relative to stages 9-8.5, 7 and 5. c. giordano et al. both from the sabatini volcanoes and the colli albani volcano (tuscolano-artemisio epoch, 600-350 ka; cf. de rita et al., 1995) it may be proposed that high eruption rates likely associated with high heat flow are favourable conditions for compensating isostatic uplift at regional scale. small scale faults also indicate a relative tectonic quiescence, whereas the development of large caldera complexes at the colli albani and sabatini volcanoes indicates the prevailing of volcano-tectonics. the localised and fast uplift of the nw-trending mt. mario rise occurred instead between 700 and 600 ka (giordano et al., 2002b) and has characteristics very similar to the uplift of the pomezia-castelporziano high. the unconformity generated by the mt. mario uplift has high relief but it is only present at the margins of the ponte galeria plateau (fig. 1) and bears no regional significance. instead, it could be related to volcano-tectonic processes which occurred just before the beginning of the volcanism in the area. with respect to previous interpretations, this reconstruction implies: 1. the recognition of eustatism as the main factor able to produce, in this area, regionally widespread unconformity surfaces, as sea level oscillated by over 100 m with a cyclicity of approximately 100 ka. these unconformities bound synthems. instead, local tectonics is responsible for the formation of high relief although localised unconformities. the best example of these two processes is the quartaccio synthem (figs. 2 and 3). this synthem is regionally represented by a terrace deposited during the oxygen isotopic stage 9, with the top at approximately 60 m a.s.l. (cf. de rita et al., 2002b). on the other hand, in the pomezia-castelporziano area, the synthem is made of several units because the area uplifted during the rise of the sea level which occurred between the low stand relative to stage 10 and the high stand relative to stage 9. as a consequence, the “older dune auct.” (table 1), which corresponds to our castelporziano dune sand, was not deposited during the “tyrrhenian” (<125 ka), but it is older, with obvious implications, as discussed above, in respect to the timing and the rate of uplift required to attain the present day elavation (max. 100 m a.s.l.; figs. 1 and 2). 2. the aurelia and the vitinia units are two distinct subsynthems, although part of the same quartaccio synthem. they can be respectively correlated to sea level high stand peaks attained during stages 9 and 8.5 (fig. 4). this new interpretation implies the chronologic constrain of the deposition of the vitinia unit at >280 ka, making the vitinia unit older than commonly thought, with large implications for the bio-stratigraphy of the area (e.g. gliozzi et al., 1997; di stefano et al., 1998; cavarretta et al., 2001 and references therein). this interpretation easily justifies several lines of evidence, such as the very low relief erosion surface at the base of the vitinia unit, which never cuts lower than the basal unconformity to the aurelia unit, the evident morphologic unity of the two units forming a single terrace with its top at 55-60 m, easily recognisable from the coast to the fluvial environment (fig. 1), and the age determinations on the interbedded of volcanic horizons, which are always older than 250 ka (cf. karner and marra, 1998). 3. the presence of a larger volcaniclastic component in the vitinia unit in respect to the underlying aurelia 127 figure 4 sea level oscillation according to waelbroeck et al., 2002 and succession of sedimentary and tectonic events in the roman coastal area after the emplacement of the tufo lionatovilla senni ignimbrites. table 2 computed uplift rates for different stratigraphic surfaces. the base of the quartaccio synthem is taken as representing the sea level during the low stand 10, whereas the successive surfaces as sea levels during high stands 8.5, 7 and 5 respectively. ssyynntthheemm uunniitt ssuurrffaaccee eelleevvaattiioonn aaggee ((kkaa)) uupplliifftt ((mm)) uupplliifftt rraattee ccoommmmeenntt ((mm aassll)) mmiinn mmaaxx ((mmmm//yy)) saccopastore top (15-30) 130 80 * 15 30 0,22 +/0,13 regional uplift campo selva top (35-45) 230-190 * 5 30 0,20 +/0,2 regional uplift quartaccio vitinia top (55-60) 284 +/3 ** 10 25 0,23 +/0,15 regional uplift quartaccio nuova california base (80) 351 +/3 *** 135 145 2,0 +/0,2 local uplift * corresponding to sea level high stands from waelbroeck et al., 2002 ** karner et al., 2001a *** villa, 1992 the sedimentation along the roman coast ... unit is also well in agreement with the datation of the first products (e.g. the capo di bove lava flow dated at 277 ka; voltaggio & barbieri, 1995 and references therein; karner et al., 2001a), which overflowed the caldera rim relative to the villa senni eruption. similarly to many other calderas, such as the campi flegrei and taupo (n.z.), volcanic activity immediately after the collapse of the caldera, and usually for several thousands of years, is confined within the collapsed area, so that outside the volcaniclastic sedimentation is greaty reduced. this time-gap therefore just represents the time necessary to the caldera to be filled by deposits, and is recorded by the marked increase in volcaniclastic sediments in the vitinia unit in respect to the aurelia unit. 4. during the middle-upper pleistocene in the roman area deformation processes result from the competition among regional uplift, localised tectonics, likely related to volcano-tectonic processes, and eruption rates (i.e. heat flow rate). the whole region, since lower pleistocene, has experienced a general tendency to regional uplift, which appears to be less significant during the climax of volcanic activity (between 600 and 300 ka ;cf. cavinato et al., 1994). the uplift resumed later (stages 9, 7 and 5) at a rate of 0.2 mm/y, suggesting that volcanism in the area, although still affected by an important hydrothermal activity (e.g. funiciello et al., 2002) is coming to an end. this is also evident by the generalised reduction of eruption rates of the latian volcanoes during the upper pliestocene (derita et al., 1995). this interpretation is substantially different from that proposed in a recent paper by karner et al. (2001b), who, based on the analyses of one stratigraphic section located in the ponte galeria area, attributed the uplift occurring after stage 9 to a refill of the magma chamber of the colli albani volcano and therefore claimed possible volcanic hazard. our data indicate instead that the resumption of uplift is a regional process occurring along the whole latian coast, not at all exclusive to the colli albani area, and well in agreement with the waning of the volcanism. 55.. aacckknnoowwlleeddggeemmeennttss the authors would like to thank s. rodani, p. paccara, p. pieruccini, r. basili and p. marsili, for discussion in the field. this work has partly been performed under the auspices of the carg project, for which we thank m. parotto. we also thank the two anonymous reviewers of the original manuscript. bbiibblliiooggrraaffiiaa ambrosetti p. & bonadonna f.p. (1967) revisione dei dati sul plio-pleistocene di roma. atti acc. gioe. di sc. nat. catania, ser. 66, 18, 33-72. anzidei m., esposito a. & benini a. (2002) using roman age submerged structures as leveling benchmarks: interaction between recent sea level variations and crustal deformation. 2002 egs general assembly, nice. abstract volume. basili r. & bosi c. (1996) morfo-litostratigrafia dell’area romana in sinistra tevere il quaternario, 99 (1), 273-280. bernardi a., de rita d., funiciello r., innocenti f. & villa i.m. (1982) chronology and structural evolutioin of albano hills volcanic complex. latium italy. workshop on the esplosive volcanism, s. martino al cimino. abstract blanc a.c. (1939) una spiaggia pleistocenica a strombus bubonius presso palidoro (roma); rend. r. acc. lincei, 2233, pp, 200 e seg.. blanc a.c. (1942) notizie sui trovamenti e sul giacimento di saccopastore e sulla sua posizione nel pleistocene laziale. paleontographia italica. memoria n. 1 l'uomo dl saccopastore; volume xlii (nuova serie, vol. xii) pag. 1-24, 3 fig. blanc a.c. (1957) on the pleistocene sequence of rome paleoecologic and archeologic correlations. quaternaria, 44, 95-109. bordoni p. & valensise g. (1998) deformationof the 125 ka marine terrace in italy: tectonic implications. in stewart i.s. . & vita-finzi c. (eds) – coastal tectonics. geological society of london, spec. publ., 114466, 71-110. cavarretta g., gioia p., mussi m. & m,r, palombo (2001) la terra degli elefanti. atti del i° cong. int. roma, cnr cavinato g.p., de rita d., milli s. & zarlenga f. (1992) correlazioni tra i principali eventi tettonici, sedimentari, vulcanici ed eustatici che hanno interessato l'entroterra (conche intrappenniniche) e il margine costiero laziale durante il pliocene superiore ed il pleistocene. studi geol. camerti, volume speciale (1992/1),109-114. cavinato g.p., cosentino d., de rita d., funiciello m. & parotto m. (1994) tectonic-sedimentary evolution of intrapenninic basins and correlation with the volcano-tectonic activity in central italy. mem. descr. geol. d’it. xlix, 63-76 chiodini g. & frondini f. (2001) carbon dioxide degassing from the albani hills volcanic region, central italy. chem. geol., 111177,, 67-83. conato v., esu d., malatesta a. & zarlenga f. (1980) new data on the pleistocene of rome. quatemaria, 2222,131-176. de rita d., funiciello r., corda l. & sposato a.. (1993) sabatini volcanic complex. di filippo m. (ed.), c.n.r. quad. ric. sc. p.f. geod. vol. 1111, 3378 de rita d., faccenna c., funiciello r. & rosa c. (1995) stratigraphy and volcano-tectonics. in trigila r. (ed.), the volcano of the alban hills, tipografia sgs, roma: 33-73. de rita d., giordano g., esposito a., fabbri m. & rodani s.(2002a) large volume phreatomagmatic ignimbrites from the colli albani volcano (middle pleistocene, italy). j. volcanol. geotherm. res. 2487, 1-22 de rita d., fabbri m., mazzini i., paccara p., sposato a & trigari a.(2002b) volcanoclastic sedimentation in coastal environmental: the interplay between volcanism and quaternary sea level change (central italy) quat. int., 95-96, 141-154. di stefano g., petronio c. & sardella r. (1998) biochronologyof the pleistocene mammal faunas from rome urban area. il quaternario, 1111 (2), 191128 c. giordano et al. 199. faccenna c., funiciello r., bruni a., mattei m. & sagnotti l. (1994) evolution of a transfer-related basin: the ardea basin (latium, central italy). basin research, 66, 35-46. funiciello r., de rita d. & giordano g. (2002) the albano maar lake (colli albani volcano, italy): recent volcanic activity and evidences of preroman age catastrophic lahar events. j. volcanol. geotherm. res (in press) giordano g., de rita d., fabbri m. & rodani s. (2002a) facies associations of rain generated versus crater lake-withdrawal lahar deposits from quaternary volcanoes, central italy. j. volcanol. geotherm. res., 2490, 1-15. giordano g., esposito a., de rita d., fabbri m., mazzini i., paccara p., funiciello r. (2002b) evoluzione geologica del margine tirrenico laziale tra il pleistocene inferiore e medio. riassunti del convegno fist, torino 2002. gliozzi e., abbazzi l., argenti p., azzaroli a., caloi l., capasso barbato l., di stefano g., esu d., ficcarelli g., girotti o., kotsakis t., masini f., mazza p., mezzabotta c. palombo m.r., petronio c., rook l., sala b., sardella r., zanalda e. & torre d. (1997) biochronology of select mammals, molluscs and ostracods from the middle pliocene to the late pleistocene in italy.the state of art. riv. it. di paleon. e str. , 110033, 368-388. karner d., renne p.r. (1998) 39ar/40ar geochronology of roman volcanic province tephra in the tiber river valley: age calibration of middle pleistocene sea-level changes. geol. soc. am. bull.; 110: 740747. karner d.b., marra f., florindo f. & boschi e. (2001a) pulsed uplift estimated from terrace elevations in the coast of rome: evidence for a new phase of volcanic activity?, earth and planetary science letters 118888 (1-2), 135-148. karner d., marra f. & renne r. (2001b) the history of the monti sabatini and alban hills volcanoes: groundwork for assessing volcanic-tectonic hazards for rome. j. volcanol. geotherm. res. 110077 (1-3), 185-215. malatesta a. & zarlenga f. (1985) il quaternario di pomezia (roma) e la sua fauna marina. boll. soc. geol. it., 110044, 503-514. malatesta a. & zarlenga f. (1986) evoluzione paleogeografico-strutturale pliopleistocenica del basso bacino romano a nord e sud del tevere. mem. soc. geol. it., 3355, 75-85. manfredini m. (1990) idrografia pleistocenica della bassa valle del fiume tevere (italia centrale). il quaternario, 33, 39-59. marra f. & rosa c. (1995) stratigrafia ed assetto geologico-strutturale dell'area romana compresa tra il tevere ed il rio galeria. geol. rom., 2299, 515-535. marra f., florindo f. and karner d. b. (1998) paleomagnetism and geochronology of early middle pleistocene depositional sequences near rome: comparison with the deep-sea δ18o record. earth and planetary science letters 115599 (3-4) (1998) pp. 147-164 milli s. (1997) depositional setting and high-frequency sequence stratigraphy of the middle-upper pleistocene and holocene deposits of the roman basin. geol. rom., 3333,, 99-136. pisias n.g., martinson d.g., moore jr. t.c., shackleton n.j., prell w., hays j. e boden g. (1994) high resolution stratigraphic correlation of benthic oxygen isotopic records spanning the last 300,000 years. marine geology 5599, 217-233. quattrocchi f., galli g., pizzino l., capelli g., de rita d., faccenna c., funiciello r., giordano g., goletto d., mazza r., mancini c. (2001) the ardea basin fluid geochemistry, hydrogeology and structural patterns: new insights about the geothermal unrest activity of the alban hills quiescent volcano (rome, italy) and its geochemical hazard surveillance. proc. x intern. conf. waterrock-interaction, villasimius, balkema ed.: 11-13. radicati di brozolo f., huneke j.c., papanastasiou d.a., wasserbutg g.j. (1981) 40ar/39ar and rb/sr age determinations on quaternary volcanic rocks. epsl, 5533, 445-456. salvador, a. (1987) unconformity bounded stratigraphic units. geol. soc. am. bull., 9988, 232237. shackleton n.j. (2000) the 100.000 year ice-age cycle identified and found to lag temperature, carbon dioxide, and orbital ecentricy. science 289, 1897-1902. smith g.a. (1987) the influence of explosive voccanism on fluvial sedimentation: the deschutes formation (neogene) in central oregon. journ. sedim. petrol., 5577, 613-629. voltaggio m., barbieri m., 1995, geochronology. in: r. trigila (ed.), 1995 the volcano of the alban hills, tipografia sgs, roma: 167-193. waelbroeck c., labeyrie l., michel e., duplessy j.c., mcmanus j.f., lambeck k., balbon e. & labracherie m. (2002) sea level and deep water terperature ghanges derived from benthic foraminifera isotopic records. quat. sc. rev. 2211, 295305. 129the sedimentation along the roman coast ... imp. muto & ggeeoommoorrpphhoollooggyy,, tteeccttoonniiccss aanndd sseeddiimmeennttoollooggyy ooff llaattee qquuaatteerrnnaarryy ffaannss bbeettwweeeenn gguuaarrddiiaa ppiieemmoonntteessee aanndd ppaaoollaa ((ttyyrrrrhheenniiaann ccooaasstt ooff ccaallaabbrriiaa,, ssoouutthheerrnn iittaallyy)) ffrraanncceessccoo mmuuttoo,, ggaaeettaannoo rroobbuusstteellllii ((**)),, ffaabbiioo ssccaarrcciigglliiaa,, vviinncceennzzoo ssppiinnaa && ssaallvvaattoorree ccrriitteellllii dipartimento di scienze della terra, università della calabria. (*) corresponding author, e-mail robustelli@unical.it abstract an integrated geomorphological, preliminary structural and sedimentological study has been carried out, in order to investigate the role of tectonic and geological setting on the late quaternary evolution of the landscape. the study area represents a portion of the onshore belt located on the eastern margin of the tyrrhenian extensional basin (coastal range). this sector of calabria consists of a thrust-pile (calabrian arc auct.), including both metamorphic and non-metamorphic rocks. structural analysis evidences four sets of major fault systems; they affect a monocline consisting of a complex folded morphostructure. the nnw-sse trending faults are dip-slip and oblique extensional faults, as suggested by superimposition of the striations. the relative chronology suggests that the youngest kinematics is represented by right-lateral normal faults. the ne-trending faults are oblique normal and dip-slip faults; the latter are compatible with the kinematics of the right-lateral nnw trend. geomorphological analysis allows three generations of alluvial-fans to be distinguished; furthermore, valley-side perched alluvial terraces occur in the lower reaches of the valley descending from the coastal range. the three generations of alluvial fans are telescopically arranged, and the apexes of the piedmont fans (1st generation) are entrenched in respect to perched alluvial terraces. the fans at issue derived from steep catchments, developed as consequent and/or subsequent river valleys debouching from the mountain front. the piedmont zone comprises the 1st generation of alluvial-fans, bordered to the west by a nearly n-s striking scarp commonly reaching up to 80 m in height to the south. the present-day coastal plain comprises the 2nd generation of alluvial-fans which lie upon and interfinger with late pleistocene coastal and eolian deposits; the latter sail the foot-zone scarp of piedmont fans. a tephra layer has been recognised within eolian deposits. on the basis of preliminary structural and morphotectonic data, the last tectonic phase responsible for the latest landscape fragmentation, was probably characterised by a nw-se trending extension direction. moreover, morphometric measurements and pre-existing offshore data support the hypothesis that, since middle-late? pleistocene time, weak tectonic subsidence, coupled with marine base level rise, constitute the main mechanisms promoting the creation of the accommodation space for fan aggradation. the quaternary alluvium is characterised by a variety of coarse-grained facies coming to be regarded as alluvial-fan facies. in particular, detailed facies analysis revealed the presence of 4 facies associations, mainly represented by debris flow, debris avalanche deposits and sheetflood facies; facies associations also allow different alluvial fan evolutionary stages to be outlined. in addition, the lithology of the bedrock outcropping within fan catchments, have been also identified as the main factors which played important roles in controlling the different depositional processes and consequently facies assemblages. riassunto è stato condotto uno studio integrato di carattere geomorfologico, strutturale e sedimentologico al fine di investigare il ruolo svolto dalla tettonica e dall’assetto geologico sull’evoluzione tardo-quaternaria di una porzione della catena costiera. essa rappresenta il margine orientale del bacino estensionale tirrenico. questo settore della calabria consiste in una struttura a falde (arco calabro auct.), comprendente rocce sia metamorfiche sia non metamorfiche. l’analisi strutturale evidenzia quattro principali sistemi di faglie, che interessano una complessa morfostruttura. le faglie nnw-sse presentano cinematismi di tipo diretto ed estensionali obliqui, come suggerisce la sovrapposizione delle strie sui piani di faglia. la loro cronologia relativa mostra che la cinematica più recente è rappresentata dalle faglie normali a componente destra. le faglie ne-sw risultano normal trascorrenti e dirette; le ultime sono compatibili con la cinematica dei sistemi nnw-sse a componente destra. l’analisi geomorfologica permette di distinguere tre generazioni di conoidi alluvionali. inoltre, terrazzi fluviali sospesi si rinvengono incastrati morfologicamente nelle porzioni più basse e più distali (verso la costa) delle valli che dissecano la catena costiera. le due generazioni di conoidi sono incastrate a cannocchiale l’una nell’altra, e gli apici dei quelle di prima generazione si incastrano tra i lembi dei terrazzi sospesi. i bacini di drenaggio che alimentano i conoidi, derivanti da un sistema di corsi d’acqua conseguenti e/o susseguenti che sboccano dal fronte montuoso, sono piuttosto acclivi. la zona pedemontana comprende le conoidi di prima generazione ed è limitata ad ovest da una scarpata a direzione circa n-s che verso sud raggiunge anche gli 80 m di altezza. la piana costiera attuale comprende le conoidi di seconda generazione, che si sovrappongono e si interdigitano con i depositi costieri ed eolici tardo-pleistocenici; questi ultimi, nei quali è intercalato un livello vulcanoclastico, suturano la scarpata che limita, verso mare, i conoidi della zona pedemontana. sulla base di dati strutturali preliminari e morfotettonici è stato possibile individuare l’ultima fase tettonica responsabile della frammentazione del paesaggio nell’area indagata, caratterizzata probabilmente da una direzione di estensione nw-se. inoltre, la misura di alcuni parametri morfometrici e la rilettura di dati sismici relativi alla piattaforma continentale sommersa consentono di ipotizzare che, a partire dal pleistocene medio-superiore?, una debole subsidenza, accompagnata dalla risalita eustatica del livello del mare, doveva costituire il principale meccanismo per la creazione dello spazio di accomodamento utile alla crescita dei conoidi. i depositi quaternari affioranti nell’area sono rappresentativi di sistemi deposizionali di conoide alluvionale. in particolare sono state distinte 4 associazioni di facies, tra cui le principali sono rappresentate da conglomerati massivi (debris-flow e debris-avalanche) e da depositi di lame di piena (sheetflood); le associazioni di facies hanno consentito, inoltre, di definire differenti stadi evolutivi nella crescita dei conoidi alluvionali. inoltre, la litologia del substrato, sottesa ai vari bacini idrografici, rappresenta un’ulteriore fattore di controllo nello sviluppo dei differenti processi deposizionali. key words: geomorphology, tectonics, sedimentology, coastal alluvial-fans, tyrrhenian coast, calabria, southern italy parole chiave: geomorfologia, tettonica, sedimentologia, conoidi alluvionali costieri, costa tirrenica, calabria, italia meridionale. il quaternario italian journal of quaternary sciences 1166(2), 2003, 217-229 218 f. muto et al. 11.. iinnttrroodduuccttiioonn the study area is located along the western coast of calabria, on the eastern margin of the tyrrhenian basin (fig. 1a). this basin developed since late tortonian times (kastens et al., 1990) as back-arc basin of the southern apennine thrust and fold belts (patacca & scandone, 1989; patacca et al., 1990). since middlelate pliocene the tyrrhenian basin was affected by extensional tectonics, responsible for the formation of perityrrhenian depressions, such as the paola slope basin (barone et al., 1982; fabbri et al., 1981; rehault et al., 1987), and the uplift of the coastal range (sorriso-valvo & sylvester, 1993). the plio-quaternary evolution of the paola slope basin has been investigated in detail by analysis of offshore data (barone et al., 1982; gallignani, 1982; argnani & trincardi, 1988; 1993; chiocci et al., 1989; chiocci, 1995; chiocci & orlando 1995). conversely, few studies have been carried out on the reconstruction of the onshore basin margin, due to the dearth of geomorphological and stratigraphical data. robustelli et al. (2002) represent the first attempt to reconstruct a middle-late pleistocene geomorphological evolution. furthermore, the only available literature on the geomorphological features of the coastal range has focused on the assessment and estimation of uplift rates (verstappen 1977; carobene et al., 1986; carobene, 1987; carobene & ferrini, 1993; bordoni & valensise, 1998) and of hillslope degradation processes (sorrisovalvo & sylvester, 1993; sorriso-valvo et al., 1998). quaternary continental and marine deposits associated with erosional landforms coexist in the study area. an integrated structural, stratigraphical and geomorphological study has been carried out in order to reconstruct the late quaternary evolution, and to state the role of tectonic and geological setting which, coupled with eustacy (robustelli et al., 2002), influenced alluvial fan development. these authors have proposed a model of evolution, according to which quaternary fan development was mainly related to phases of climate amelioration following glacial periods, but just before interglacial highstands were approached; progressively increasing moisture and temperatures allowed bio-chemical rock degradation, and consequent increased runoff favoured removal of slope-waste materials, which promoted alluvial-fan development, mainly by gravity processes. sea level highstand induced coastal erosion of fan toes, resulting in foreshortened longitudinal profiles and fan dissection (e.g. harvey et al., 1999); sediment input was probably channelled away from subaerial basins, enabling progradation over the shelf. the subsequent lowering of sea level promoted fan-trenches lowering and the progressive emergence and dissection of the paola basin shelf; products of slope degradation during glacial periods, probably, had to be conveyed from the mountain catchments to fill paleovalleys, detected by means of seismic profiles analysis (chiocci et alii, 1989; chiocci, 1995; chiocci & orlando, 1995), thus disabling fan-development. fig. 1 a northwestern sector of the calabrian arc (after tortorici et. al., 1982, modified) with the location of the study area; b geological sketch map of the study area. a settore nord-occidentale dell’arco calabro, (da tortorici et al., 1982, modificato) ed ubicazione dell’area di studio; b carta geologica dell’area di studio. 219geomorphology, tectonics and sedimentology... 22.. ggeeoollooggiiccaall sseettttiinngg the northwestern sector of the calabrian chain consists of a flat-lying nappe (calabrian arc auct.) which constitutes the morphostructural height of the coastal range (fig. 1a); in particular it consists of highgrade metamorphic rocks of the polia copanello unit, tectonically overlapping low-grade metamorphic rocks of the castagna unit and bagni formation (amodio morelli et al., 1976; dietrich, 1976; colonna & compagnoni, 1982); these units overlapped the ophiolitic complex (liguride complex, ogniben, 1973; messina et al., 1981, boullin, 1984; knott, 1987; dewey et al., 1989), and the carbonatic units (amodio morelli et al., 1976). thrust-sheets were cut by four sets of major faults, the relative ages of which have been determined by sylvester et al. (1987). in the study area, a miocene sedimentary sequence rests on the crystalline-metamorphic basement of the coastal range; it constitutes the sedimentary infilling of the correlative amantea basin, dated to upper tortonian by di nocera et al. (1974), outcropping to the south (mattei et al., 2002; muto & perri, 2002). in the study area, the miocene deposits consist (fig. 1b) of two unconformable sequences. the first one is characterised by conglomerates and sandstones, underlying the 2nd sequence constituted by yellow calcarenites and grey-blue clays; the latter have been recognised in boreholes along the coastline. this succession exhibits a general monoclinalic attitude, with a growing dip towards west. late quaternary continental deposits rest unconformably on the basement and the miocene sedimentary sequence. the coastal range is a horst which started to uplift since plio-pleistocene time (tortorici, 1982a; 1982b), and produced the progressive isolation of the crati valley from the tyrrhenian sea, accompanied by the formation of the paola basin. this basin extends along the n-s direction, on the west side of the study area, from the sangineto zone to the capo vaticano zone. the paola basin has an architecture controlled by extensional tectonic phases and contractional events (canu & trincardi, 1989); moreover, it exhibits a depocenter localised immediately behind the continental slope, and is characterised by high depositional gradients (fabbri et al., 1981; gallignani 1982; barone et al., 1982; finetti & del ben, 1986; chiocci, 1995). 33.. pprreelliimmiinnaarryy ssttrruuccttuurraall aannaallyyssiiss the northwestern sector of the tyrrhenian margin is characterised by a complex structural arrangement which is limited by the falconara fault zone (turco et al., 1990) to the south and the guardia piemontese morphostructure to the north. the oldest structures are represented by thrust faults and by two generations of folds, with axes oriented roughly from nnw-sse to nne-ssw. these folds, which involve all the tortonian deposits, are asymmetric and verging to the east. these structures are cut by transtensive fault systems, that represent the result of the latest tectonic phases related to the tyrrhenian basin quaternary spreading. fault-slip data were collected in 8 measurement sites, for a total amount of 120 measures. measurement sites were positioned in miocene deposits, whereas quaternary deposits do not display any signs of deformation. nevertheless, quaternary tectonics is clearly demonstrated by evidence of uplifted tyrrhenian strandlines (sea caves at about 12 m a.s.l. located near to cetraro, close to the north of the study area, carobene et al., 1986; carobene, 1987; bordoni & valensise, 1998), and by cross-cut relationships between marine terraced deposits and fault systems (tortoricii et al., 2002); furthermore, from a geomorphological point of view, the fact that remnants of perched alluvial terraces are not related to any present-day or past landform and are located close to the escarpment bounding the mountain front support the quaternary tectonic activity. literature data (tortorici et al., 2002; muto & perri, 2002; tortorici et al., 1995) were used to constrain the chronology and the stress field of the last fault activity. a strong fit exists between the orientation of the main meso-faults and macro-fault systems, plotted in fig. 2 structural data collected in the miocene deposits. a rose diagram of the main meso-faults collected; b rose diagram of the macro-fault systems mapped in the study area; c lower hemisphere stereographic projection of the nnw trending fault system with the latest kinematic indicators on the planes; d lower hemisphere stereographic projection of the ne trending fault system with the latest kinematic indicators on the planes; e, f lower hemisphere stereographic projection of the nw-se and e-w trending fault systems. dati strutturali rilevati nei depositi miocenici. a rose diagram relativo alle principali mesofaglie misurate. b rose diagram relativo alle macro strutture cartografate; c proiezione stereografica, emisfero inferiore, del sistema di mesofaglie nnw-sse con gli ultimi indicatori cinematici rilevati sui piani; d proiezione stereografica, emisfero inferiore, del sistema di mesofaglie ne-sw con gli ultimi indicatori cinematici rilevati sui piani; e, f proiezione stereografica, emisfero inferiore, del sistema di mesofaglie nw-se e e-w. 220 rose diagrams (figs. 2a and 2b), suggesting that fault slip data well clarify the last kinematics of macro-faults. the main system faults are nnw-, ne-, nwand e-trending. the occurrence of overlapping kinematic indicators on the same fault plane, along with the presence of different slip directions on fault planes having the same strike and dip, allow multiphase tectonics to be outlined. the latest fault kinematics is showed in figs. 2c-f. in particular, fault slip data of the ne-trending systems suggest that their kinematic chronology shifts from left-lateral normal to normal dip-slip faults. the nnw-trending system faults show dip-slip and oblique normal movements; the superimposition of the striations allows a relative chronology of their movement to be fixed, i.e. from dip-slip to right-lateral normal faults. the left lateral ne-trending faults system, compatible with the nnw-trending dip-slip system, is older than the latest phase of movement characterised by dip-slip netrending normal faults and relative nnw-trending right lateral normal faults. the eand nw-trending fault system are oblique normal faults and are characterised by a kinematics which is locally superimposed to left strike-slip ones. the latest kinematic indicators are consistent with an ese-wnw extension interpretation, which represents the main mode of deformation of the calabrian arc since middle pleistocene times (e.g. tortorici et al., 1995). 44.. ggeeoommoorrpphhoollooggyy quaternary deposits of the study area, representing mainly marine and alluvial environments (argnani & trincardi, 1993; sorriso-valvo & sylvester, 1993; sorriso-valvo et al., 1998; robustelli et al., 2002), are hosted in a narrow coastal strip, which can be considered the onshore counterpart of the paola basin infilling. these deposits are limited inland by the coastal range, essentially evolved by slope replacement mechanisms and river dissection. as a consequence of this evolution the west-facing slope of this mountain ridge shows welldefined triangular facets as isolated remnants of the n-s trending fault scarp, partly dismantled. the hydrographic network formed as a response to the coastal range uplift, producing steep catchments debouching seaward from the mountain front, which led to the emplacement of three generations of alluvial fans. as a general rule the drainage pattern follows the main fault system (sylvester et al., 1987; sorriso-valvo & sylvester 1993) and shows several asymmetric valleys. geomorphic evidence suggest that the e-w consequent streams were interrupted and deflected by neand n-s trending subsequent streams, at least in the northern sector of the study area. some morphometric data of the main stream catchments have been calculated, such as the mean drainage basin slope (ds) and the drainage basin area (da), the sweep angle, as (sensu viseras et al., 2003) and the mean slope (fs) of the fans. from these data it can be observed that the source catchments of the major rivers are very steep: the mean slope of the drainage basins, in fact, ranges from 31.43 to 40.65%. on the contrary, the fans are gentler, with mean slopes approximately around 10-14% or lower, except in the case of the t. laponte (fs = 15.48%). on the basis of data provided by robustelli et al. (2002), three generations of alluvial-fans, telescopically arranged, have been distinguished. from a geomorphological point of view, the study area consists of different, narrow geomorphological zones, parallel to the coast and limited by approximately n-s trending scarps probably not related to faults (fig. 3). the piedmont zone comprises the 1st generation of alluvial-fans which are telescopically inset in respect to remnants of perched alluvial terraces (fig. 4a), gently sloping seaward but apparently not related to any present-day or past landform, which hang in some of the main river valleys dissecting the coastal range. a nearly n-s striking scarp borders the piedmont zone; local remnants of eolian deposits, with continental fauna, are well preserved on the basal portion of the foot-zone scarp. quite a similar stratigraphic situation characterises the piedmont zone of the central coastal range (sorriso-valvo & sylvester, 1993), where sandy eolian deposits outcrop along the foot-zone scarp and underlie the youngest alluvial fans. amino-acid racemization dating on helix sp. fix the emplacement of eolian sands at about 70 kyr b.p. (sorriso-valvo, pers. comm.). furthermore, they rest on buried gravel deposits that constitute the bulk on which post-eolian sedimentation took place, as inferred by boreholes data, and are commonly capped by thin layers of slope deposits produced by scarp retreat. hence these eolian sands clearly postdate the 1st generation of alluvial fans (middle-late? pleistocene) and predate the 2nd one (upper pleistocene-holocene) (fig. 4b). the most recent alluvial-fans, late holocene to recent in age, develop close to the present-day coastline, and are substantially inactive and subject to very slight river dissection. they lie upon and are entrenched within late pleistocene–holocene coastal deposits, consisting of beach sands and gravels as well as eolian sands (fig. 3). the bulk of the piedmont zone, reaching an elevation of about 130 m a.s.l., consists of the oldest generation of coalescent alluvial-fans, which show a sweep angle 60°. a particular attention must be given to a huge fan developed at the mouth of t. laponte, which is entrenched in – and partly rests on – the dissected t. maddalena alluvial fan. from the geomorphic relationships between the two alluvial bodies, the laponte fan is obviously younger. although its drainage basin is not the widest (da = 6.32 km2), it is extremely large, with an as value close to a square angle and the feeder channel filled with great amounts of sediments (cf. sorriso-valvo et al., 1998), assuming a typical “mushroom” shape (viseras et al., 2003) in plan view. in the sector between valle santa maria and the t. maddalena, at the toe of the piedmont zone, the lower and younger alluvial fans occur. their sweep angles commonly vary from 30-40°, reaching higher values for the t. mercaudo (60°) and the t. trappeto (about 90°). the above mentioned eolian sands, which taper upslope the nearly n-s striking scarp bordering the piedmont zone, are quartzolithic in composition; they have abundant lithic grains, and mostly equal amounts of quartz and feldspar (qm20 f18 lt62). feldspar is dominantly plagioclase. aphanitic lithic fragments (lm86 lv0 ls14) include abundant metamorphic lithic fragments, represented by phyllite, fine-grained schist and minor fine-grained gneiss and amphibolite; sedimentary f. muto et al. 221 fig. 3 geomorphological sketch map of the study area. schema geomorfologico dell’area di studio. geomorphology, tectonics and sedimentology... 222 lithic fragments are subordinate and include micritic and sparitic limestone, dolostone and metalimestone lithic fragments. coarse–grained rock fragments include plutonic (mostly granodiorite and minor granite) and gneiss rock fragments. the abundant metamorphic detritus is derived from the diverse tectonostratigraphic units of the coastal range, bagni, castagna and polia copanello units (amodio morelli et al., 1976; dietrich, 1976; colonna & compagnoni, 1982), whereas the sedimentary detritus is derived from mesozoic to miocene sedimentary strata of the san donato and verbicaro units (amodio morelli et al., 1976) and the miocene sedimentary successions (di nocera et al., 1974; mattei et al., 2002; muto & perri, 2002). a fine-textured, greyish tephra layer, about 20 cm thick, is interbedded within their upper portion and consists of impure volcanoclastic sands. volcanic detritus includes pumice fragments, having vitric texture, and sometimes including plagioclase, pyroxene and biotite crystals. rare volcanic lithic fragments exhibiting microlitic texture consist of particles having plagioclase, biotite and pyroxene microlithes, and a vitric groundmass. in addition to volcanic detritus, the sample contains various non-volcanic detritus, which includes single quartz and feldspars, metamorphic and carbonate lithic fragments, and coarse-grained plutonic rock fragments. micrite and microsparite interstitial component constitutes matrix and early cement of the sample. 55.. aalllluuvviiaall--ffaann ssttrraattiiggrraapphhyy on the basis of geomorphic analysis, described in the previous section, the quaternary alluvium consists of perched valley-side terraced deposits and alluvial fan deposits; the latter comprise two generations of alluvial fans, telescopically arranged. alluvial-fan deposits are characterised by the dominance of conglomerates; finegrained facies were not observed. the clast lithology slightly varies over the study area; dominant clasts include ophiolitic units, phyllites, gneiss, schists, granites and sedimentary rocks. because of the dearth of exposures which affect valley-side terraced deposits, sedimentary facies analysis has concerned only alluvial-fan facies. in particular a number of stratigraphic sections have been measured in order to give the sedimentary logs of fig. 4, because of the vertical cliffs which confine the piedmont zone allufig. 4 overviews showing the morphologic relationships among the perched alluvial terraces, the mountain front and the piedmont alluvial fans (a) and between the piedmont and the coastal alluvial fans (b). foto panoramiche che illustrano i rapporti tra i terrazzi fluviali sospesi ed il fronte montuoso ed i conoidi pedemontani (a), e tra i conoidi pedemontani e costieri (b). f. muto et al. vial fan; therefore sections were obtained along river incision and road cuts and extend parallel to fan-slope up to 9 m in width, and are representative of the uppermost portion of alluvial fans. as far as coastal-plain alluvial fans are concerned, thanks to excavations for the foundation of buildings located in the middle portion of t. trappeto coastal fan, the relative sedimentary log (fig. 4) is given; unfortunately no sections are available for t. mercaudo and t. maddalena coastal fans, because of the lack of artificial and natural exposures, the latter owing to slight river dissection. the base of both generations of alluvial fans is not exposed; the maximum thickness, provided by well log data, is 45 m and 35-40 m for the coastal and piedmont alluvial deposits, respectively. according to robustelli et al. (2002), the latest phases of fan development occurred during climate amelioration following glacial periods, when increasing moisture and temperatures, enabling bio-chemical rock degradation, and increasing run-off allow slope-waste materials to be removed, mainly by gravity and subordinately tractive processes. 55..11 ffaacciieess aannaallyyssiiss the quaternary alluvium is characterised by a variety of coarse-grained lithofacies coming to be regarded as alluvial-fan facies. in particular detailed facies analysis revealed the presence of 5 sedimentary facies, discussed below, which are described on the basis of clast-size, bedding, sedimentary structures and shape of the units. three sedimentary logs are given in fig. 4; they are representative of the uppermost part of the t. trappeto piedmont fan, t. maddalena piedmont fan and t. trappeto coastal fan. ffaacciieess 11 - ssttrruuccttuurreelleessss,, ccoobbbbllee ttoo bboouullddeerr--ssiizzee ccoonngglloo-mmeerraattee no good exposures of this facies occur in the study area; a number of very small outcrops occur along roads ascending t. laponte alluvial-fan apex zone, and as subordinate facies alternating in t. maddalena alluvial-fan deposits. the latter allows facies analysis to be made. this facies consists of massive, monomictic, matrix to clast supported conglomerates of cobble to boulder grade. basal surfaces of these beds, up to 1.8 m thick, are sharp and display fairly erosional features. matrix content is locally abundant; it consists of a mixture ranging from silt to pebble, seemingly of the same composition as the largest clasts; the latter are angular to subangular in shape, and it is worth noting the presence of shattered ones. fabric is disorganized, although uncommon, crudely coarse-tail inverse grading occurs. ffaacciieess 22 - ssttrruuccttuurreelleessss,, ccllaasstt--ssuuppppoorrtteedd ccoonngglloommeerraattee massive, poorly sorted, sheet conglomerates comprise this facies. bed thickness varies between 0.4 and 1.2 m. basal bedding contacts are sharp and slightly irregular, with relief of up to 0.15 m; scour surfaces may be observed, but they are very uncommon. the debris consists of pebble to cobble-size clasts, ranging from angular to subrounded in shape. matrix in an unsorted mixture varying between silt and fine-grained pebble, and is rarely sufficiently abundant to support clasts. fabric is disorganized, although the longest a-axes of some elongate clasts may be seen parallel to paleoflow and imbricated a(p), a(p)a(i). grading is absent or basal inverse grading locally occurs. ffaacciieess 33 - iinnvveerrsseellyy ggrraaddeedd,, ccllaasstt--ssuuppppoorrtteedd ccoonngglloommee-rraattee inversely graded, clast-supported, poorly to moderately sorted sheet conglomerates characterise this facies. basal surfaces of the beds, up to 0.5 m in thickness, are sharp and non erosive. pebble to cobble-size clasts comprise this facies, ranging from angular to subrounded in shape. matrix, varying between sand to fine pebble, is never sufficiently abundant. inverse-grading is well developed; inverse to normal grading is uncommon (fig. 5a). clast fabric locally displays a preferred a(p)a(i) clast orientation. ffaacciieess 44 –– hhoorriizzoonnttaallllyy,, ccrruuddeellyy ssttrraattiiffiieedd ccllaasstt--ssuuppppoorr-tteedd ccoonngglloommeerraattee this facies is characterised by vertically alternating couplets of clast-supported sheet conglomerates (fig. 5b); beds of this facies, up to 0.4 m thick, have sharp, non erosive basal bedding contacts. the debris consists of subangular to subrouded pebble to cobble grade and pebble to pebbly granule gravels. the coarse gravel units, occasionally clast-thick, are massive and moderately sorted; crude normal gradind may occur. imbrication, locally well developed, is variable, showing a(p)a(i) and a(t)b(i) fabric modes. the finer grained beds seem to be more extensive than the coarse grained ones; they are moderately to well sorted and no grading has been observed. pebblesize clasts show a local a(t) b(i) fabric mode. outsized clasts, of coarse pebble to fine cobble grade, are sparsely present and their long axis are aligned both parallel and normal to bedding planes. ffaacciieess 55 –– lleennttiiccuullaarr,, ccllaasstt--ssuuppppoorrtteedd ccoonngglloommeerraattee this facies rests on facies 2 and 3; it consists of moderately to well sorted, clast-supported, lenticular gravel units up to 0.2 m thick and varying between 0.6 and 1.1 m in width. granule to fine pebble-size clasts comprise this facies. grading is absent, although crudely normal grading locally occurs. imbrication may be well developed, showing a(t)b(i) fabric mode. 55..22 iinntteerrpprreettaattiioonn aanndd ffaacciieess aassssoocciiaattiioonnss detailed facies analysis revealed the presence of five facies, the interpretation of which has been described accordingly as follows. lateral and vertical facies associations, coarse-grained texture, disorganized fabric, together with geomorphic analysis suggest that the depositional events were of very high-energy and consistent with an alluvial-fan depositional system. ffaacciieess 11:: ddeebbrriiss--aavvaallaanncchhee ddeeppoossiittss the conglomerates of facies 1 are massive, monomictic, matrix to clast supported and cobble to boulder grade; these features suggest high-energy depositional events. furthermore, the angular nature of the gravel clasts, locally shattered, their monomictic composition and their poor sorting are interpreted as deposition by debrisavalanche events (sorriso-valvo, 1988; yarnold & 223geomorphology, tectonics and sedimentology... lombard, 1989; yarnold, 1993; blair & mcpherson, 1994). this facies results from failure of a large fractured and weathered bedrock cliffs which, during downward fall was characterised by partial disintegration; in fact shattered boulders, but also very weathered angular clasts, may be observed. a clayey reddish-brown paleosol layer, with wavy upper and lower boundaries, rests on this facies association (robustelli et al., 2002). ffaacciieess 22:: ddeebbrriiss--ffllooww ddeeppoossiittss the massive, sheet-like, non erosive based, poorly sorted, clast-supported nature of this facies suggest that depositional events were of high-energy, i.e. unconfined debris-flow. according to shultz (1984), this facies is interpreted as depositional evidence of pseudoplastic debris flow; in particular these units may represent the deposits of cohesionless debris-flow (smith & lowe, 1991; sohn et al., 1999) dominated by frictional grain interactions in which clast collision is hampered, resulting in the lack of inverse grading and clast imbrication. the local a(p)a(i) clast fabric indicates that brief or transient laminar shear affected debris flow (e.g. nemec & postma, 1993). beds with coarse-tail basal inverse grading are indicative of non-shearing rigid plugs resting on the basal part of flows affected by intense laminar shear (nemec & postma, 1993; johnson & rodine, 1984; sohn et al., 1999). ffaacciieess 33:: ccllaasstt--rriicchh ddeebbrriiss--ffllooww ddeeppoossiittss facies 3 is interpreted as the deposits of high-concentration flows. the low matrix content, the framework support, the a(p)a(i) clast imbrication and the upward coarsening trend are thought to be evidence of clast-rich debris flow (shultz, 1984). generally the above described features are consistent with deposition of unconfined, cohesionless debris flows (nemec & steell, 1984; shultz, 1984; smith, 1986; smith & lowe, 1991), and the inverse grading being representative of granular flows in which a dispersive pressure dominates during motion (lowe, 1982; todd, 1989; sohn et al, 1999). this facies may also be interpreted as representative of very high sediment-concentration dispersions, such as hyperconcentrated flood-flows, i.e. dilution of debris flows (pierson, 1980; pierson & scott, 1985; ridgway & decelles, 1993; smith & lowe, 1991 among others). ffaacciieess 44:: sshheeeettfflloooodd ddeeppoossiittss the dominance of horizontally stratified conglomerates, characterised by vertically alternating couplets of coarse and fine grained beds, indicates that high-energy tractional processes were involved. in particular, the tabular conglomerate sheets suggest that deposition was laterally extensive. as a whole this facies is interpreted as being formed by deposition of unconfined sheetflood pulses well testified by the alternating couplets of different clast-size (e.g. blair & mcpherson, 1994). high-density flood-flow interpretations, in particular hyperconcentrated flood flows (sensu smith, 1986; smith & lowe, 1991), may also be suggested by the clast fabric, including the outsized ones within the finergrained beds. ffaacciieess 55:: ssttrreeaamm--ffllooww ddeeppoossiittss facies 5 is thought to be deposited by low-energy stream flow. evidence for stream-flow processes include 224 fig. 5 logs of the alluvial fan conglomerates. numbers refer to lithofacies. letters refer to facies associations (see the text for details). sezioni stratigrafiche dei c o n g l o m e r a t i alluvionali. le lettere si riferiscono alle litofacies. le sigle si riferiscono alle associazioni di facies (si veda il testo per i dettagli). f. muto et al. framework-support, a(t)b(i) imbrication, sorting and the lenticular geometries of individual units. this facies is associated with beds of facies 2 and 3, on which it commonly rests, and are representative of deposition in small channels that developed over fan-slope after debris-flow deposition; in particular these lenticular gravel beds are thought to be produced by fine-fraction winnowing on the debris-flow by overland water flows (blair & mcpherson1994). ffaacciieess aassssoocciiaattiioonnss lateral and vertical facies association, coarsegrained texture, disorganized fabric, together with geomorphic analysis suggest that the depositional events were of very high-energy and consistent with an alluvialfan depositional system. four facies associations have been distinguished and discussed below. ffaacciieess aassssoocciiaattiioonn aa is restricted to the base of the upper portion of t. maddalena piedmont fan and t. laponte fan; the few and scattered road-cut sections and observations of the cliffs from a distance indicate that this facies association consists of vertically alternating debris flow and, subordinately, debris avalanche deposits. very uncommon beds of facies 5 may occur. ffaacciieess aassssoocciiaattiioonn bb characterised the upper portion of t. maddalena piedmont fan. the most common facies is the massive, poorly sorted, clast-supported sheet conglomerates (facies 2). subordinate facies are represented by inversely graded conglomerates (facies 3) and clast-supported, lenticular units (facies 5) of granule-pebble grade. ffaacciieess aassssoocciiaattiioonn cc constitutes the bulk of the upper portion of t. trappeto piedmont fan. it consists of alternating debris flow (facies 2, 3) and sheetflood (4) facies; lenticular units (facies 5) produced by fine-fraction winnowing on the debris-flow are also common. ffaacciieess aassssoocciiaattiioonn dd is restricted to the upper portion of t. trappeto coastal fan and consists of debris flow deposit (facies 2) usually capped by conglomerate lenses of facies 5. sheetflood facies are uncommon. this facies association, though analogous to facies association c, is characterised by a decrease in clastsize. for instance debris-flow deposits of pebble to cobble grade and pebble to fine cobble grade characterised t. trappeto piedmont and coastal fan, respectively (robustelli et al., 2002). 66.. ddiissccuussssiioonn aanndd ccoonncclluussiioonn on the basis of all data collected by means of an integrated geomorphological, structural and sedimentological approach, interesting issues can be addressed to discuss the late quaternary fan evolution along the northwestern sector of the coastal range. a strong structural control of drainage pattern is highlighted. to the north of the study area stream directions follow strikes and fold axes trends of the miocene sedimentary cover. moving southward the drainage network, although following faults pattern, is superimposed over the fold limb of the miocene succession. as resulting from structural and morphotectonic studies addressed to paleostress reconstruction in an area close to the south (muto & perri, 2002; tortorici et al., 2002), the last tectonic phase was probably characterised by a nw-se trending extension direction and was responsible for the creation and re-activation of netrending faults; furthermore, it caused the reactivation of the nnw-trending ones with right lateral transtensive kinematics. this tectonic phase can be ascribed to middle-late? pleistocene on the basis of cross-cut relationships between marine terraced deposits and fault systems (tortorici et al., 2002); it could have been the cause of landscape fragmentation, by interrupting the continuity of a possible pre-existing coastal plain and producing valley-side perched alluvial terraces, as also testified by the lack of landforms related to the perched terraces (figs. 3 and 7a). the following development of the 1st generation of alluvial fans tapered upslope the triangular facets and sealed the fault scarps (fig. 7b) created by the previous block-faulting. since that time fan development was mainly related to eustacy, as suggested by robustelli et al. (2002) and briefly reported in section 1. the bathymetric maps of the continental shelf 225 fig. 6 alluvial fan facies. a inverse grading sheet conglomerates interpreted as pseudoplastic debris flow (see the text for details); b alternating couplets of sheetflood facies; a(p) fabric mode is well noticeable. particolari delle facies che caratterizzano i conoidi alluvionali. a conglomerati a gradazione inversa interpretati come la deposizione ad opera di debris flow pseudoplastici; b alternanza di coppie di livelli conglomeratici a differente granulometria interpretati come depositi di lame di piena (sheetflood); risulta ben evidente la disposizione dell’asse maggiore dei clasti, parallela alla superficie di stratificazione (a(p)). geomorphology, tectonics and sedimentology... (present seafloor isobaths; argnani & trincardi, 1988; chiocci et al., 1989), as well as the maps reporting the reconstruction of the last glacial erosional surface and the total thickness of holocene deposits provided by chiocci et al. (1989) and chiocci & orlando (1995), show patterns of seafloor dip and slope scarps orientation, which widely match with the strikes of the main fault system observed onshore, i.e. ne-, nnw-, nwand e-trending faults as the well-known falconara fault (turco et al., 1990) it may suggest that the above mentioned tectonic phase has lasted at least till late upper pleistocene. moreover, offshore from capo bonifati (just a few kilometres northwest of the study area) and from guardia piemontese, sharp breaks in slope approximately at depths of 75-90 m b.s.l. can be clearly recognised. these scarps border offshore two flat surfaces, which chiocci et al. (1989) simply interpret as erosional terraces related to sea-level stillstands. the complete lack of late pleistocene marine terraces in the study 226 fig. 7 main stages of late quaternary morphotectonic evolution of the study area (see the text for details). principali fasi dell’evoluzione morfotettonica tardo-quaternaria dell’area in esame (si veda il testo per i dettagli). f. muto et al. area, which, on the contrary, developed during pleistocene times and were tectonically uplifted to different heights both in the northern and the southern sector of the tyrrhenian coast of calabria (carobene & dai pra, 1990; carobene & ferrini, 1993; tortorici et al., 2002) could be explained in two different ways: (i) the rates of sea-level rise and tectonic uplifts were substantially equal in the study area, so that the terraces never formed (cinque et al., 1993); (ii) the terraces really did form indeed and were subsequently submerged for subsidence phenomena involving this onshore sector of the paola basin. in the latter case, it could be hypothesised that the flat surfaces, occurred on continental shelf and identified from seismic data, would tentatively be related to the above mentioned wave-cut marine platforms (buried by holocene deposits), and be the submerged counterpart of the adjacent, raised late pleistocene terraces. what is more, the presence of huge bioherm structures, up to several tens of metres high, just close to the slope break of these flat morphologies (chiocci et al., 1989) supports this idea: in addition, encrusting marine organisms of this kind usually develop in limpid and relatively shallow water (photic zone) and their relics often outcrop at the top of marine terraces of different ages all along the south tyrrhenian sea coast (e.g. brancaccio et al., 1990; carobene & dai pra, 1990; iannace et al., 2001; riccio et al., 2001; scarciglia et al., 2003). their extreme vertical extension could be related to their rapid growth upwards concurrently with the progressive land subsidence and relative sea-level rise, just to maintain their suitable life environment. furthermore, the landward migration of holocene depositional depocenters (chiocci et al., 1989; chiocci, 1994) and their location at the mouth of the major streams dissecting the coastal range and debouching along the west coast (argnani & trincardi, 1988; 1993), which clearly indicate a strong control by sediment input from continental feeding sources, could have also been favoured by subsidence. some parameters used in the morphometric analysis of alluvial fans (e.g. viseras et al., 2003) may support this hypothesis; in fact weak tectonic subsidence, coupled with marine base level rise, may constitute the main mechanisms promoting the creation of the accommodation space for fan aggradation. in fact, it is worth noting that to the north of the study area uplift rates are very low (0.05 mm/yr, carobene et al., 1986; bordoni & valensise, 1998). in addition, robustelli et al. (2002) already highlighted that important fan development occurred in the study area during transitions toward interglacial periods, characterised by climatic amelioration and significant sea-level rise. both the peculiar “mushroom” shape and the high sweep angle values measured for late pleistoceneholocene fans (fig. 3), can be interpreted as due to low subsidence and sea-level rise, combined with high sediment input, which produce a retrograding stacking pattern, with a mountain embayment associated with an expansion of the fan (viseras et al., 2003). furthermore, the lack of fault evidence within the alluvial fan successions could be related just to the low rates of subsidence. as far as facies analysis are concerned, factors that control alluvial fan facies assemblages have been identified. moving northward, t. maddalena and t. trappeto alluvial fan deposits consist of slightly different facies associations (fig. 5). t. maddalena piedmont fan was built solely by sediment gravity flows (debris avalanche and debris flow processes), whereas t. trappeto piedmont fan deposits consist of alternating sediment gravity flows (debris flow processes) and fluid gravity flows (sheetflooding). in both cases, secondary processes, i.e. overland flows, caused locally winnowing of the top surfaces. some features, such as climate, vegetation types, tectonic setting etc. are thought to have been approximately the same during fan construction. even though the t. maddalena catchment area is larger than the t. trappeto one (12.02 km2 vs. 6.26 km2), this feature, as other fan and catchment morphometric data, are not prerequisites to promote different facies assemblages (e.g. blair, 1999). according to blair (1999) and blair & mcpherson (1994), lithology of the bedrock underlying fan catchments is thought to control the slight differences in depositional processes and relative facies associations, i.e. weathering caused differences in sediment particle-size, influencing permeability, which may promote sediment gravity flows vs. fluid gravity flows. although the bulk of the bedrock underlying fan catchments at issue comprises quite similar lithologies, major exposures of schists and phyllites of the ophiolitic units in the t. maddalena fan catchment (28% vs. 15%) may be considered as the main key factor in the differences among facies assemblages. furthermore, the finer-grained facies, characterising coastal fans in respect to piedmont ones (robustelli et al., 2002), may be interpreted as the sedimentary response to different alluvial fan evolutionary stages, reflecting the progressive increase of drainage basins size, coupled with the decrease of drainage basins slope (e.g. blair & mcpherson, 1994). aacckknnoowwlleeddggmmeennttss the authors are grateful to mr. francesco colonnese for the preparation of thin sections. they also wish to thank prof. l. carobene and prof. t. pescatore for their comments and suggestions helpful for the improvement of the manuscript. this work is financially supported by murst 60% (prof. s. crivelli). rreeffeerreenncceess amodio-morelli l., bonardi g., colonna v., dietrich d., giunta g., ippolito f., liguori v., lorenzoni s., paglionico a., perrone v., piccarretta g., russo m., scandone p., zanettin-lorenzonii e. & zuppetta a. 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(ed.s), conglomerates in basin analysis. sepm pacific section symposium book, 6622, 9-32. 229 ms. ricevuto il 6 maggio 2003 testo definitivo ricevuto il 19 settembre 2003 ms. received: may 6, 2003 final text received: september 19, 2003 geomorphology, tectonics and sedimentology... imp. santangelo iinntteerraazziioonnee ttrraa tteettttoonniiccaa rreecceennttee ee pprroocceessssii ggeeoommoorrffiiccii nniiccoolleettttaa ssaannttaannggeelloo dipartimento di scienze della terra – università degli studi di napoli “federico ii” riassunto l’obiettivo di questo lavoro è quello di individuare i principali indicatori geomorfologici di attività tettonica recente e di evidenziare le possibili interazioni tra tettonica e processi erosivo/deposizionali nei vari contesti geomorfici (fluviali, di versante, carsici e costieri). particolare attenzione è stata rivolta al problema della taratura degli indicatori ed alla definizione della loro sensibilità. da questa analisi è emerso che molti di essi presentano dei limiti e che la possibilità del loro ritrovamento è funzione del contesto geologico e geomorfologico in cui ci si trova. esistono contesti “più favorevoli” alla genesi ed alla conservazione degli indicatori (aree caratterizzate da tassi elevati di deformazione, con bassi tassi dei processi erosionali e caratterizzate da affioramenti di litologie più conservative) e contesti “meno favorevoli”. in ogni situazione la ricerca degli indicatori di attività tettonica recente dovrà essere rigorosa e calibrata in funzione dello scenario in cui verrà eseguita. abstract the interaction between active tectonics and geomorphic processes.this paper was addressed to point out the main geomorphic indicators of active tectonics and to clarify the possible interactions between tectonics and erosional/depositional processes in various geomorphic scenarios. for each group of processes (fluvial, slope, karst and coastal) the most common indicators have been selected trying also to discern the typology of the tectonic movement (uplift, faulting, tilting) that they can outline. the problem of the “calibration” and sensitivity of the various indicators was also faced. the analysis outlines that the use of many indicators is limited by several factors represented by the difficulty on finding precise chronological constraints, by their low degree of preservation and by the convergence between some landforms actively and passively controlled by structure. moreover, due to the variable erodibility of the outcropping rocks and to the variable rates of deformation with respect to the rates of geomorphic processes, the various geomorphic scenarios can be more or less favourable for the genesis and preservation of the indicators. the absence of geomorphic indicators will not necessarily outline the absence of active tectonics, but could represent the response to tectonics active with rates lower than the rates of the main geomorphic processes. for this reason, the research for the indicators will have to be detailed and calibrated in relation to the scenario in which it will be carried out. parole chiave: indicatori geomorfologici – tettonica recente – processi geomorfici. keywords: geomorphological indicators – active tectonic – geomorphic processes. il quaternario italian journal of quaternary sciences 1166(1), 2003, 27-34 iinnttrroodduuzziioonnee per affrontare un discorso sugli indicatori geomorfologici di attività tettonica recente è innanzitutto necessario chiarire cosa si deve intendere per “tettonica recente”(active tectonics o active faulting della letteratura inglese ed americana). il termine “recente” è infatti abbastanza ambiguo e necessita di una precisazione cronologica più accurata, ed il termine “tettonica” risulta abbastanza generico e non dà alcuna informazione sulle modalità e sul tipo di deformazione in oggetto. consultando la letteratura è possibile associare all’aggettivo “recente” una finestra temporale compresa tra l’attuale e 104 anni ed indicare con il termine più generico di “neotettonica”, tutti i movimenti e le deformazioni che ricadono in un intervallo più ampio (104 – 106 anni). una definizione cronologica così rigorosa però, può risultare sterile, in quanto una comprensione approfondita dell’evoluzione della deformazione nel tempo può richiedere una indagine su intervalli temporali più ampi. ciò accade, per esempio, quando le metodologie adottate, o le aree in studio, non hanno una sensibilità tale da consentire una risoluzione cronologica così dettagliata. in queste condizioni, anche l’approccio su una scala temporale più ampia (ultimi 200-300 ka per esempio), potrà fornire delle preziose informazioni sul comportamento tettonico recente dell’area in studio. per tale motivo, si può ritenere questa finestra temporale relativamente flessibile e si può stabilire di tararla ogni volta in funzione delle caratteristiche dell’area in studio e delle metodologie adottate. altra cosa importante da chiarire è il tipo di deformazione tettonica che si vuole ricercare è cioè moti verticali “in toto” della superficie terrestre, quali sollevamenti e subsidenze a carattere regionale, oppure fagliazioni e quindi dislocazioni verticali, oblique ed orizzontali o, ancora, basculamenti della superficie terrestre dovuti a piegamenti o a tilting localizzati. queste precisazioni sono necessarie per scegliere gli indicatori più significativi ed in particolare per chiarire quale sensibilità essi devono avere per assumere tale ruolo. 28 n. santangelo iinnddiiccaattoorrii ggeeoommoorrffoollooggiiccii facendo riferimento a quanto detto nel paragrafo precedente ed analizzando la letteratura esistente su questo argomento, è stata prodotta la tab. 1, nella quale i principali indicatori sono raggruppati in funzione dei processi geomorfici e delle diverse tipologie di deformazione. processi fluviali l’interazione tra movimenti tettonici e processi fluviali può essere ricondotta ad una generale variazione dei rapporti tra erosione e sedimentazione lungo un corso d’acqua in funzione della capacità erosiva, del tipo di trasporto, dei tassi e delle modalità del movimento (continuo o discontinuo). indicatori geomorfologici attività tettonica recenteprocessi interazioni erosivo tettonica/ deposizionali moti verticali “in toto” fagliazione basculamenti processi duplicazione di terrazzi episodi di ed anomalie nella loro variazione variazione dei incisione o distribuzione generale. morfologia rapporti tra erosione e aggradazione non anomala distribuzione letto (sensu sedimentazione lungo giustificati da sola aree in erosione ed in ouchi, 1985; il corso d’acqua in fluviali componente aggradazione shumm 1986) funzione di: capacità climatica anomalie profilo erosiva e tipo di terrazzi longitudinale trasporto, tassi e valli tronche (hanging modalità del valleys) sollevamentovalli a calice (wine-glass subsidenza (continuo valleys) /discontinuo) anomalie tracciato anomalie nella morfologia e nei gradienti delle conoidi alluvionali (sensu bull, 1977) dislocazione depositi fluviali dissezione e/o dislocazione fasce seppellimento fasce detritiche pedemontane detritiche scarpate (“nastri”) in pedemontane in roccia e/o detriti funzione dei rapporti di versante indice smf (bull & tra tassi di mcfadden (1977) sollevamentosubsidenza e velocità di sedimentazione. attivazione e/o riattivazione di processi franosi variazione contesto dislocazione deviazione microambientale. riempimenti asse di improvvisa dislocazione morfologie accrescimento formazione di doline carsici carsiche di stalagmiti da crollo sia in roccia anomalie di crescita (forti & che in coperture concrezioni potschpil, detritiche. 1984; 1985) formazione dislocazione depositi variazione dei lagune marini basculamenti rapporti tra erosione (sollevamento con dislocazione morfologie regionali o /sedimentazione e emersione barre costiere locali di quindi sommerse) anomalie altimetriche di terrazzi arretramento/progradaavanzamento e terrazzi marini (ois 5 e zione in funzione dei costieri arretramento successivi) rispetto alle tassi e delle modalità spiagge paleoquote eustatiche di sollevamentodissezione o subsidenza sommersione delta. tab.1 principali indicatori geomorfologici di attività tettonica recente main geomorphological indicators of active tectonics nel caso di moti verticali di carattere regionale e ad una scala temporale secolare, gli indicatori geomorfologici sono rappresentati da episodi di incisione (sollevamenti relativi) o di aggradazione (abbassamenti relativi) delle aree in movimento e da formazione di veri e propri terrazzi su tempi più lunghi (migliaia o decine di migliaia di anni). ovviamente, la ricerca di questi indicatori è facilitata nelle porzioni montane ed intermedie dei bacini idrografici mentre risulta più complessa nelle zone costiere, dove l’interazione con le oscillazioni eustatiche rende più difficile l’individuazione degli effetti indotti sui processi fluviali dalla sola componente tettonica. a tale riguardo merrits et al. (1994), in uno studio comparato dei terrazzi fluviali di tre bacini idrografici adiacenti, in un’area della california settentrionale soggetta ad uplift nel tardo quaternario e nell’olocene (ultimi 250 ka), hanno evidenziato come l’influenza dell’eustatismo sul terrazzamento sia intensa nella porzione costiera e di pianura alluvionale dei bacini in esame, mentre nelle zone montane il terrazzamento è causato quasi interamente dal sollevamento tettonico. la risposta di questi corsi d’acqua all’uplift di lungo termine è stata la formazione di terrazzi erosionali spaiati (unpaired strath terrace); la distribuzione asimmetrica delle superfici rispetto all’asse vallivo viene interpretata dagli autori come la risposta ad un processo di sollevamento continuo, mentre l’ampiezza di queste superfici e l’entità 29interazione tra tettonica recente e ... del dislivello esistente fra i vari ordini sono funzione della capacità erosiva del corso d’acqua e delle modalità del sollevamento (fig 1). per quanto riguarda invece gli indicatori geomorfologici di fagliazione in ambiente fluviale , la casistica è molto più ampia; tralasciando le evidenze di fagliazione di depositi alluvionali recenti (che costituiscono un indicatore in senso stratigrafico, geologico più che geomorfologico), gli indicatori più utilizzati sono rappresentati dalla duplicazione di uno stesso ordine di terrazzi fluviali, dall’anomala distribuzione di aree in aggradazione e/o in erosione, da anomalie nel profilo longitudinale (sensu burnett & schumm, 1983), da piccole scarpate rettilinee che dislocano superfici deposizionali tardoquaternarie-oloceniche e da susseguenze o gomiti fluviali impostate su depositi tardo-pleistocenici. anche le valli tronche (hanging valleys) e le valli a calice (wine-glass valleys) vengono comunemente elencate tra gli indicatori di dislocazioni verticali ma esistono dei casi di convergenza morfologica che pongono dei limiti al loro utilizzo (cfr. paragrafo successivo). lo studio delle conoidi alluvionali fornisce ulteriori utili indicatori (keller,1986) sia per l’individuazione di episodi di fagliazione recente (presenza di scarpate trasversali o brusche variazioni di pendenza nel gradiente longitudinale di apparati tardo pleistocenici–olocenici ) che per una quantificazione relativa dei tassi di movimento lungo il lineamento in questione. in quest’ultimo caso infatti la presenza di apparati sovrapposti (con deposizione concentrata nelle aree apicali) od incastrati (fig. 2) può indicare tassi di sollevamento differenziati (rispettivamente maggiori e minori) del fronte montuoso rispetto alla capacità di dissezione dei torrenti alimentatori delle conoidi (bull, 1977). ancora, un anomala distribuzione delle caratteristiche morfometriche (area, gradiente) di apparati di conoide coevi, disposti al piede di un fronte montuoso di origine tettonica, può indicare la presenza di settori caratterizzati da diversi tassi di sollevamento o la presenza di importanti lineamenti trasversali (hooke, 1972; rockwell et al.,1984). in altri casi le conoidi possono essere spostate orizzontalmente lungo faglie trascorrenti e quindi possono riuscire ad indicare direzione e verso del movimento oltre che i tassi di scorrimento, qualora sia possibile la determinazione della loro età. gli esempi più significativi a riguardo sono quelli identificati lungo la faglia di san andreas in california (keller et al., 1982). per quanto riguarda infine le variazioni indotte sui corsi d’acqua da movimenti plicativi localizzati, ouchi (1985) e schumm (1986) ritengono che l’aumento o la diminuzione di gradiente longitudinale di un corsa d’acqua prodotti da basculamenti della superficie associati al sollevamento di una anticlinale o alla subsidenza di una sinclinale, produrrebbero sul breve termine delle brusche variazioni della morfologia del letto fluviale. le varie possibilità, simulate in laboratorio, sono riportate in fig. 3 e sono funzione del tipo di trasporto prevalente (carico sospeso, braided etc). fig. 1 differenti morfologie trasversali di sezioni vallive con formazione di terrazzi erosionali spaiati in funzione di tassi di sollevamento differenti e di diversa capacità erosionale del corso d’acqua. gli schemi c) e d) si riferiscono ad un tasso di sollevamento due volte più alto di quello degli schemi a) e b). da merrits et al.,1994, modificato. model of unpaired strath terrace development along a meandering bedrock river for different uplift rates and river sizes. sketches c) and d) are for a rate two times grater than sketches a) and b). from merrits et al.,1994, modified. 30 processi di versante le interazioni più importanti tra eventi tettonici e processi di versante possono essere ricondotte ad episodi di dissezione e/o di seppellimento delle fasce detritiche pedemontane poste al piede di un fronte montuoso o di un versante impostato su di una faglia, in funzione dei rapporti tra tassi di sollevamentosubsidenza e tassi di sedimentazione. in tale contesto gli indicatori geomorfologici saranno relativi solo ad episodi di fagliazione e potranno darci informazioni relative alla tipologia del movimento (diretto, inverso o trascorrente) e/o sull’età relativa del movimento. oltre alle classiche evidenze stratigrafiche, rappresentate dalla fagliazione di detriti di versante recenti, gli indicatori morfologici più utilizzati in questo settore sono rappresentati da piccole scarpate di faglia ("nastri") in roccia o detriti, che interrompono la continuità del profilo longitudinale di un versante di faglia. e’ questo un esempio di indicatori che presentano però vari limiti. non sempre infatti la scarpata è il prodotto diretto di un movimento tettonico ma può essere legata ad erosione differenziale tra litologie più e meno conservative che vengono in contatto lungo la faglia (caso molto frequente in appennino ed anche nelle alpi, panizza et al., 1978; brancaccio et al., 1979; 1986; cinque et al.,1991; ascione & cinque, 1997; bartolini & peccerillo, 2002) o ad un costipamento differenziale nell’ambito dei detriti di versante. inoltre l’assenza di tale indicatori non implica necessariamente l’assenza di attività tettonica recente, in quanto la scarpata potrebbe non essere presente perché sepolta dai detriti, qualora i tassi di uplifit/subsidenza eguaglino quelli di sedimentazione della falda detritica, o perché cancellata dagli agenti esogeni qualora i processi di arretramento della scarpata stessa avvengano con tassi maggiori di quelli del sollevamento. a tale riguardo sono significativi i lavori di wallace (1977) , di mayer (1986) e di nash (1986) relativi alle variazioni morfologiche nel tempo di scarpate di faglia in funzione del tipo di processo prevalente (fig. 4). un’altra anomalia del profilo longitudinale di un versante di faglia che può indicare una ripresa dell’attività tettonica in tempi recenti è la presenza di un tratto basale caratterizzato da maggiore pendenza rispetto alla porzione sommitale (brancaccio et al., 1979; cinque et al., 1991; bartolini & peccerillo, 2002). in questi casi bisognerà porre particolare attenzione a casi di convergenza morfologica legati ad erosione selettiva. scartate le situazioni in cui lungo la faglia vengono a contatto litologie a forte contrasto morfoselettivo, profili longitudinali di versanti di faglia caratterizzati da bruschi aumenti di pendenza basali, potranno essere considerati ottimi indicatori di tettonica recente, soprattutto se impostati su litologie tenere. n. santangelo fig. 2 formazione di conoidi sovrapposte (a) o incastrate (b) ai piedi di un fronte montuoso in sollevamento in funzione di differenti tassi di uplift. in a i tassi di sollevamento sono maggiori che in b. da bull, 1977. formation of superimposed fans (a) or entrenched fans at the foot of an uplifting mountain front for different rates of uplift. the rate uplift of a) is major than b). from bull,1977. 31 suo piede e la lunghezza del versante in linea d’aria. questo indice riflette un bilancio ideale tra la tendenza dei processi di versante e dei processi fluviali a creare un andamento sinuoso, in pianta, del versante e la tendenza dei processi tettonici di sollevamento verticale a produrre un andamento rettilineo. bassi indici di sinuosità pertanto, saranno indicatori di versanti lungo i quali i tassi di sollevamento tettonico prevalgono su quelli dei processo erosivo-deposizionali. anche in questo caso sussistono possibilità di casi di convergenza morfologica, per esempio con versanti di linea di faglia per i quali il basso indice di sinuosità è legato soltanto ad una esumazione recente del piede del versante per morfoselezione e non ad un movimento recente lungo la faglia. discorso a parte meritano i casi di attivazione e/o riattivazione di processi franosi che spesso si verificano in aree caratterizzate da tettonica recente ed in particolare in concomitanza di grossi eventi sismici (vedi terremoti del friuli e dell’irpinia). tali fenomeni sono da considerarsi semplicemente degli “effetti” della tettonica recente ma non possono assumere il ruolo di indicatori a causa dei numerosi fattori di controllo passivo che condizionano la loro distribuzione. processi carsici in ambiente carsico gli indicatori più significativi di attività tettonica recente sono rappresentati dalle anomalie di crescita di concrezioni di grotta. la dislocazione diretta di morfologie carsiche epigee ed ipogee (paleosuperfici carsiche dislocate a gradinata, complessi carsici fagliati e sospesi rispetto agli attuali livelli di base; bellucci et al., 1983; santangelo & santo 1991; piccini, 1997) rappresenta infatti un buon indicatore di fagliazione sul lungo termine, ma sono abbastanza rare le segnalazioni di evidenze di questo interazione tra tettonica recente e ... fig. 3 risultati della simulazione in laboratorio della risposta di un corso d’acqua meandriforme a carico misto prevalente ad a) un inarcamento di tipo anticlinalico e b) ad una subsidenza legata ad una deformazione di tipo sinclinalico. l’ordine temporale è dall’alto verso il basso. da ouchi, 1985. adjustment of a mixed load meandering river to a) anticlinal uplift and b) synclinal s u b s i d e n c e across it. time sequence is expressed in the order from top to bottom. from ouchi,1985. fig. 4 variazioni morfologiche di una scarpata di faglia nel tempo in funzione dei processi di degradazione prevalenti. da wallace,1977. change in fault scarp morphology with time for different faultscarp degradation processes. un altro indicatore di attività tettonica recente lungo un versante di faglia o lungo un fronte montuoso, è rappresentato secondo bull e mc fadden (1977) dall’ indice di sinuosità del versante (indice smf), dato dal rapporto tra la lunghezza del versante misurata lungo il 32 tipo sul breve termine. le anomalie di crescita delle concrezioni di grotta (forti & postpischl, 1984:1985) invece costituiscono degli ottimi indicatori soprattutto in campo paleosismologico; lo studio di queste anomalie infatti, oltre a fornire informazioni sulla tipologia della deformazione (fagliazione o basculamenti), consente di accedere ad una registrazione di eventi sismici che va ben oltre l’arco temporale coperto dai dati storici, normalmente utilizzati in paleosismologia. a ciò si aggiunge un altro prezioso requisito che le concrezioni hanno rispetto ad altri indicatori e cioè la possibilità si essere facilmente datate con metodi radiometrici (serie u/th). processi costieri anche le interazioni tra tettonica e processi costieri sono riconducibili ad una variazione dei rapporti tra erosione e sedimentazione e quindi tra arretramento e progradazione della linea di costa in funzione dei tassi e delle modalità della deformazione tettonica. la situazione in questo caso è complicata anche dalle oscillazioni eustatiche del livello marino e dalle loro possibili interazioni con i movimenti tettonici. gli indicatori più utilizzati sono senz’altro rappresentati dalle anomalie altimetriche di terrazzi marini e/o di paleomorfologie costiere deposizionali ed erosionali (cordoni costieri, solchi, falesie), rispetto alle paleoquote eustatiche. l’analisi della distribuzione planimetrica di queste anomalie aiuta a comprendere la modalità e la tipologia del movimento tettonico. nella finestra temporale in cui abbiamo confinato la tettonica recente ricadono gli stage isotopici 2 e 1 a cui corrispondono paleoquote eustatiche negative; la possibilità di trovare in superficie indicatori di paleolivelli marini, implica quindi necessariamente la presenza di attività tettonica. le aree del nostro pianeta in cui sono conservate gradinate di terrazzi marini tardo pleistocenici ed olocenici sono generalmente quelle interessate da forti tassi di dislocazione (sollevamento) e deformazione (piegamento e fagliazione) legati direttamente ai movimenti delle placche litosferiche (subduzione e rifting) o ad attività vulcano tettonica. fanno eccezione le aree del nord europa e del nord america in cui le gradinate di terrazzi tardo pleistoceniche ed oloceniche riflettono la risposta isostatica della crosta e del mantello alla deglaciazione tardo pleistocenica. per tutte le altre aree non interessate da tassi di movimento tali da consentire la deformazione e l’emersione di linee di riva del tardo pleistocene superiore e dell’olocene, tra le quali rientra la maggior parte delle aree costiere italiane (fatta eccezione per la calabria, la sicilia e le aree vulcaniche come ischia ed i campi flegrei per esempio), l’attività tettonica recente potrà essere evidenziata almeno dalla anomala distribuzione altimetrica delle linee di riva dell’ultimo interglaciale (cosentino & gliozzi, 1988; romano , 1992). lliimmiittii ddeeggllii iinnddiiccaattoorrii quanto finora detto consente di constatare che i vari indicatori elencati presentano, di frequente, dei limiti di applicabilità o di validità, riconducibili alle seguenti casistiche. casi di convergenza morfologica sono molto frequenti e legati al classico problema del controllo attivo o passivo della struttura sulle forme del rilievo: è il caso delle fault scarps e delle fault-line scarps, delle anomalie di tracciato della rete idrografica (antecedenze e sovrimposizioni, offsets dovuti a susseguenza etc.) e per tale discussione si rimanda alla letteratura (thornbury 1954, 243-275 pp.; bartolini & peccerillo, 2002). altre situazioni classiche di convergenza morfologica si realizzano in casi di controllo climatico e/o antropico: esempio tipico è quello dei fenomeni di erosione e di aggradazione recenti lungo gli alvei fluviali legati ad oscillazioni climatiche secolari (piccola età glaciale per es. ) che limitano effettivamente l’utilizzo di questi elementi come indicatori di attività tettonica recente. cronologia la maggior parte degli indicatori citati spesso fornisce indicazioni cronologiche soltanto relative e pertanto non consente di ricavare informazioni quantitative sui tassi della deformazione; pochi sono gli indicatori che risultano associati a depositi su cui sia possibile effettuare datazioni assolute (tefra e paleosuoli intercalati nelle successioni continentali o associati a terrazzi, depositi marini, concrezioni di grotta). scarso grado di conservazione alcuni indicatori (p.es piccole scarpate di faglia) possono essere cancellati dai processi geomorfici. la possibilità di conservazione di un indicatore dipende da vari fattori quali litologia, entità e tassi dei processi geomorfici, contesto climatico, entità della deformazione. non sempre l’assenza di indicatori sarà significativa di assenza di tettonica recente ma potrà indicare, per esempio, bassi tassi di deformazione rispetto ai ritmi dei processi erosionali predominanti . distribuzione localizzata ( scarsa rappresentatività) alcuni indicatori, presi singolarmente non sono significativi e sono invece necessarie delle associazioni di forme per rendere “visibile” la deformazione tettonica. e’ il caso per esempio degli offsets laterali su faglie trascorrenti: una semplice deflessione di drenaggio non sarà un indicatore “sufficiente” di movimenti recenti lungo una faglia trascorrente ma, associato ad altri indicatori (dossi lineari, scarpate, sag ponds vedi fig. 5), risulterà un indicatore di ottima qualità. ccoonncclluussiioonnii prima di concludere si può fare una breve panoramica sulla situazione della ricerca italiana su questo tema. i vari progetti (“morfotettonica”, “geomorfologia strutturale “, “catene e pianure”) portati a termine tra gli anni ’80 e ‘90 ed i vari congressi e convegni ( fiastra, camerino, parma, siena) organizzati sul tema, hanno delineato il quadro morfostrutturale del territorio italiano con un buon grado di approfondimento a scala regionale, per quanto riguarda l’evoluzione di medio e lungo termine (104 – 106 anni). meno approfondito risulta invece il quadro relativo all’evoluzione della tettonica recente, n. santangelo sismici e quindi del contesto geodinamico in cui si trova l’area di studio (vedi fig. 6). a questi fattori si possono aggiungere l’entità ed i tassi dei processi erosionali e l’erodibilità delle litologie interessate. i contesti più favorevoli sono quindi rappresentati da aree interessate da grossi tassi di deformazione, bassi tassi di erosione e aggradazione ed impostate su litologie più resistenti. (situazione opposta per le meno favorevoli). in contesti sfavorevoli gli indicatori significativi sono a volte indiretti (per esempio distribuzione dei depocentri deposizionali in una conca intermontana, anomalie della forma e dei gradienti di conoidi alluvionali etc.) e devono essere ricercati con maggiore scrupolosità ed attenzione. si può quindi concludere affermando che la ricerca degli indicatori di attività tettonica recente deve essere rigorosa e calibrata in funzione dello scenario in cui viene eseguita. l’approccio metodologico deve essere necessariamente multidisciplinare e quindi l’analisi geomorfologica deve integrarsi con quella paleosismologica, geologico-strutturale, geocronologica al fine di produrre un quadro dettagliato dell’evoluzione delle deformazioni nel tempo e nello spazio. in particolare essa deve contribuire a definire i tassi di movimento su breve e lungo termine, a fornire informazione sui tassi dei processi erosionali che interagiscono con l’attività tettonica, a proporre dei modelli quantitativi di evoluzione dei singoli processi in rapporto a diversi tassi di deformazione (nash, 1986; cinque et al.,1991;1995), a migliorare i dati di cronologia assoluta e relativa. 33interazione tra tettonica recente e ... fig. 5 associazioni di forme indicatrici di attività recente lungo una faglia trascorrente. da keller,1986. assemblage of landforms associated with active strike-slip faulting. from keller,1986. fig. 6 diversa evidenza geomorfologica delle faglie attive in funzione del tempo di ritorno e della magnitudo degli eventi sismici. da slemmons and depolo, 1986. geomorphological features of active faulting related to recurrence interval and magnitude of earthquakes. from slemmons and depolo, 1986. anche perché il contesto geologico e geomorfologico della nostra penisola fa sì che gli effetti al suolo delle deformazioni siano poco evidenti. si può infatti affermare che esistono contesti più o meno favorevoli alla produzione ed alla conservazione degli indicatori di tettonica recente. slemmons & depolo (1986) per esempio, sottolineano come la possibilità di avere buone evidenze morfologiche di fagliazione superficiale in corrispondenza di faglie attive, sia funzione della magnitudo e del tempo di ritorno degli eventi i possibili sviluppi futuri dell’analisi geomorfologica in questo campo potranno fornire importanti contributi nella individuazione delle aree caratterizzate da tettonica recente e nella selezione dei siti in cui l’approfondimento delle ricerche potrà essere produttivo. ciò soprattutto in relazione a problematiche relative alla quantificazione dei tassi di deformazione sul breve e sul lungo termine, alla determinazione del tempo di ritorno dei terremoti ed alla zonazione (macro e micro) della pericolosità sismica . bbiibblliiooggrraaffiiaa ascione a. & cinque a. 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(1977) profiles and ages of young fault scarps, north central nevada. geol.soc.am. bull.,88,1267-1281. 34 ms. ricevuto il 7 gennaio 2003 testo definitivo ricevuto il 13 maggio 2003 ms. received: january 7, 2003 final text received: may 13, 2003 n. santangelo imp.bondesan ppaalleeooeennvviirroonnmmeennttaall rreeccoonnssttrruuccttiioonn ffrroomm llggmm ttoo hhiissttoorriiccaall ttiimmee iinn tthhee lloowweerr ccooaassttaall ppllaaiinn ooff tthhee ppiiaavvee rriivveerr.. pprreelliimmiinnaarryy ppoolllleenn aannaallyyssiiss oonn aa 2200 mm ccoorree ooff llaaggoooonn aanndd fflluuvviiaall sseeddiimmeennttss aallddiinnoo bboonnddeessaann11,, mmiirrccoo mmeenneegghheell11,, aannttoonneellllaa mmiioollaa22 && ggiiaannnnaa vvaalleennttiinnii22 1 dept. of geography, university of padova, via del santo 26 35123 padova 2 dept. of biology, university of padova, via g. colombo 3 35131 padova abstract this work presents the first results of a multidisciplinary study in the flood plain of the piave river located ne of the venice lagoon. the aim of the work is to reconstruct the late quaternary geomorphological evolution of the area. this study is part of a wider research on the veneto-friuli plain based on geomorphological surveys, remote-sensing, sediment analyses, archaeological and historical map analyses. in the frame of this study, three cores of 20 m depth were collected along a n-s transect 20 km long between san donà di piave and the coast of the adriatic sea. the transect crosses the present course of the piave river and its fluvial ridge, while the corings were performed on the surface of old flat marshes, now reclaimed. pollen-stratigraphical data and 14c dates are presented for the intermediate core of palazzetto. the results of radiocarbon dating indicate that the sequence spans the last glacial maximum (lgm) and the holocene. at the base of the sequence, a peat layer (21,250±150 yr bp) is characterised by dominance of cyperaceae (pollen, epidermal and roots fragments, fruits) as many other peat layers formerly described by other authors in the veneto and friuli plain. fine fluvial sediments attributed to the piave river bury the basal peat. the changes in the local plant communities from fresh water to brackish/salt water communities have been recognised at the depth of ca. 6 m. this level testifies the flandrian transgression not yet investigated in the san donà di piave area. the geochronological dating and the pollen analysis of the three cores will let us know the dynamic of the ingression of the sea at ne of the venice lagoon. at the top of the core the pollen assemblage of a peat layer (500±70 yr bp) suggests the presence of a marsh environment. riassunto ricostruzione paleoambientale dell’area planiziale costiera del basso piave dall’ultimo massimo glaciale all’olocene. analisi polliniche preliminari di una carota di 20 m di sedimenti fluviali e lagunari. questo contributo riporta i primi risultati di un’indagine multidisciplinare condotta nella pianura alluvionale del fiume piave a ne della laguna di venezia. lo scopo della ricerca è di comprendere l’evoluzione geomorfologica dell’area nel quaternario recente. essa è parte di un vasto studio della pianura veneto-friulana, condotto attraverso indagini geomorfologiche, remote-sensing, analisi dei sedimenti, analisi di mappe storiche e di reperti archeologici. in questo contesto sono stati eseguiti tre carotaggi fino a 20 m di profondità, collocati lungo un transetto n-s della lunghezza di una ventina di km tra san donà di piave e la costa settentrionale del mare adriatico. il transetto attraversa l’attuale corso del fiume piave e il suo dosso fluviale. i carotaggi sono stati eseguiti in corrispondenza di antiche aree paludose, oggi bonificate. in questo lavoro vengono presentati i risultati dello studio della sequenza di palazzetto, collocato circa a metà del transetto. lo scarso contenuto pollinico dei sedimenti analizzati limita l’utilizzo dei dati pollinici alla ricostruzione dei cambiamenti avvenuti nell’ambiente di sedimentazione. i risultati della radiodatazione di quattro livelli di sedimenti organici fanno ritenere che la sequenza si sia deposta tra l’ultimo massimo glaciale e l’olocene recente. alla base sono stati individuati strati torbosi (21.250±150 a bp) a prevalenti cyperaceae (polline, frammenti di radici e di epidermidi, frutti), caratterizzati dalla stessa flora pollinica di altri depositi torbosi, già descritti da vari autori in sequenze della pianura veneta e friulana, di età compresa tra i 18.000 e i 22.000 anni bp. le torbe basali sono ricoperte da depositi sabbiosi e limosi fluviali attribuiti alle esondazioni del piave e depostisi in un breve periodo di tempo, circa 2000 anni. le analisi polliniche indicano un radicale cambiamento nelle comunità vegetali locali nei sedimenti argillo-torbosi collocati a circa 6 m di profondità (6520±150 a bp): comunità vegetali di acqua dolce sono sostituite da comunità tipiche di ambienti di acque salate/salmastre. questi sedimenti sono la prima testimonianza della trasgressione flandriana nella zona di san donà di piave. alla sommità della sequenza è stato analizzato uno strato torboso di età radiometrica di 500±70 a bp (cal ad 1300-1500); l’associazione pollinica esaminata suggerisce la presenza locale di comunità di piante prevalentemente erbacee di palude e nessun indizio di insediamenti umani. key words: late glacial maximum, holocene, stratigraphy, geomorphology, pollen and spores analysis, piave river, north adriatic. parole chiave: ultimo massimo glaciale, olocene, stratigrafia, geomorfologia, analisi di polline e spore, fiume piave, nord adriatico. il quaternario italian journal of quaternary sciences 1166(1bis), 2003, 183-192 iinnttrroodduuccttiioonn the paleoenvironmental reconstruction of the venice area has been the aim of several multidisciplinary researches (bortolami et al., 1977; castiglioni & favero, 1987; blake et al., 1988; correggiari et al., 1996; mullenders et al., 1996; serandrei barbero et al., 2001; kent et al., 2002). the main task of these studies is the improved knowledge of subsidence phenomenon in the past and the effects of human activities on its evolution. the nearby coast located ne is poorly known, even if its evolution in the past influenced or has been influenced by the hydrological conditions of the venice area. therefore a wider research on the veneto-friuli plain has started some years ago. it is based on geomorphologic surveys, remote-sensing, sediment analyses, archaeological and historical map analyses (bondesan et al., 1998; bondesan, 2000; bondesan & furlanetto, 2000; bondesan et al., 2002a; bondesan et al., 2002b; ghedini et al., 2002). in the framework of this study, we collected three continuous cores along a 20 km long n-s transect that goes from san donà di piave to the coast of the adriatic sea (fig. 1), hopefully contributing to the study of evolution in the venetian coastal plain of the past by means of pollen and spore analysis. in this paper 14c dates and pollen-stratigraphic data are 184 a. bondesan et al. presented for the intermediate core of palazzetto. the studied area is located along the modern course of the piave river, at the north-eastern border of the lagoon of venice, into the coastal plain between sile and livenza rivers. the territory is characterised by a dense hydrographical network, where the main rivers (piave, sile and livenza) which are south-eastwards oriented, flow in connection with the artificial canals dug in xiii century by the republic of venice. due to the hydraulic reclamation, a closed network of small canals and ditches crosses the whole plain. there are many evident traces due to the ancient shorelines, back from the present coastline; from them we can establish the existence of at least two paleo-piave deltas, now extinct and buried. the plain surface is mainly constituted by agricultural fields, most of which laying below the sea level: the lower elevations are found northern of caorle (livenza mouth), where they locally reach values lower than 4 m below sea-level. higher heights mainly stand along fluvial ridges and old dunes closed to present littoral. all this territory was scattered by wide swamps, marshes and lagoons until the end of xix century when the reclamation started, joined with a strong reduction of old dunes and fluvial ridges. it is well known that during the last strong cold pulsation of the pleistocene the sea level dropped more than one hundred metres below the present one. because of the shallowness of the adriatic sea, the coast in the lgm shifted towards south for more than 200 km to the latitude of ancona. the present north adriatic sea was then a fluvial plain where all the rivers of the po plain converged and perhaps joined. the venetian plain was then rich of marshes and swamps that left extended layers of peat dating from ca. 22,000 to 18,000 yr bp (bondesan et al., 2002b). at the same time, huge glaciers flowed south from the alps and the majority of them reached the plain. the glacier of the piave river basin had two snouts at quero and vittorio veneto where it left its moraines. an end moraine of the vittorio terminus has been dated to 17,670 ± 320 yr bp (bondesan, 1999); from that date onwards the glaciers started to retreat as a consequence of the climatic improvement. along with the glaciers retreat, the sea level started to lift and the coast shifted again to the north (flandrian transgression). according to brambati (1985) the coastline reached a position similar to the present one at about 7-6000 yr bp, while correggiari et al. (1996) fixed the maximum sea ingression around 5000 calendars years bp, by the dating of lagoonal sediments. the transgression probably joined with changes in the rivers hydrological state, and this led to an instability of the lower reaches of the rivers that could be affected by avulsions as happened for the rhine and mose delta as described by stouthamer (2001). an avulsion node is that of san donà di piave, from which starts the fluvial ridge crossed by the transect described in this paper. ggeeoommoorrpphhoollooggiiccaall oouuttlliinneess the plain belonging to the piave river (fig. 2) is a complex form, generated by deposition and erosion phenomena mainly due to fluvial sediments, with contributions of fluvio-glacial and marine deposits. looking from the point where the mountains merge into the plain, at the height of nervesa, we found a progressive change from the large fan of the foothills to the low plain and finally to the proper coastal plain, this last one being the result of the interference of marine and fluvial dynamics. looking at the altimetry the surface lies between 80 m above sea level at nervesa and 4 m below sea level along the coast. the system of the high plain is formed by a sequence of great, flat, gravelly alluvial fans that lie one overlaid to the other on the prealpine border (bondesan, 2000). the nervesa fan, which constitutes the nervesa unit, is furrowed by the present piave river bed (bondesan et al., 2002b); it started to form soon after the upper-pleistocene fluvial diversion of the piave river from the montebelluna to the nervesa course. the fan is not very steep, showing a dip of 3-4‰ at the apex and 1.5-2‰ uphill of the alignment treviso-ponte di piave; downhill it is less than 1‰. its gravelly sandy sediments extend eastward up to oderzo, coming close to river livenza. there are five main recognizable fluvial ridges and all of them start from the fan apex at nervesa; they are related to paleo-piave beds and to the present fluvial ridge of the piave river, which is continuously elevated on the plain as far as the mouth. almost all the traces, visible on aerial photographs, situated on the left wing of the nervesa fan, can be classified as braided streams; they have been dated from 4170±60 yr bp to present day. descending towards the sea, the low plain is found where the hydrographical network becomes denser, the gradient decreases and the sediments become finer. here we find fluvial ridges both along present river courses and also along abandoned rivers. sometimes, a small watercourse interprefig.1 location map of the studied area. 185paleoenvironmental reconstruction from lgm ... ted as relict hydrography remains on the top of the ridge. this process leads to the formation of a network of ridges surrounding closed or semi-closed hollows where the drainage is barred. s. donà di piave constitutes an avulsion node, from which different watercourses in different times depart. there are four main ridges branching out from this point across the coastal plain. the western one is the piave vecchia ridge (pv in fig. 2), rimming the venice lagoon border. eastwards, the taglio da re ridge (tr in fig. 2) gains the cavetta channel, back of jesolo; it is the outreach of a diversion channel excavated by the venetians in 1534. nowadays the ridge is overflowed by a scant reclamation channel. the present main piave river bed is artificially excavated and it gets eraclea flowing straight for some kilometres. it follows the left flank of the ridge (pc in fig. 2), 3 km wide and 3 m height over the surrounding plain, probably created by a former ancient piave. it shows branches and crevasse splays with traces of ancient channels well documented in antique and modern maps. the piovan (or piveran) channel (cp in fig. 2) is very interesting: it flows along a great ridge starting from s. donà di piave and it turns southeast after the confluence with the grassaga channel toward stretti. the ridge is 3 km wide and 2 m high at s. donà di piave, but it becomes narrow and flat as far as it looses any morphological evidence. the via annia, an ancient roman way, follows the path of the ridge and changes its direction when it crosses the mound through a roman bridge whose remains were found along the grassaga channel; then the ridge follows on to the archaeological site of cittanova. the fluvial ridges define large low-laying interfluvial areas, where paleo-river beds and paleo-lagoon channels are clearly visible on aerial photo-fig. 2 geomorphological sketch map of the piave river plain. 186 graphs. the medieval and modern ingression of the lagoon is marked along the stretch north of taglio del sile, going along the line linking s.donà di piave to boccafossa (livenza river) (castiglioni & favero, 1987; murst, 1997). the lagoon deposits spill at the surface and we assert they are very recent. organic samples of surface lagoon sediments gave a geo-chronological age of 1200±190 yr bp (utc 7801), 955±55 yr bp (rome – 1180) and 658±39 yr bp (utc 7802) (personal communication of henk berendsen, 1998; bondesan et al., in press-b). these data confirm that the lagoon sediment sealed the depressions between the older main fluvial ridges in historical times. along the coast we find the littoral unit (bondesan et al., 2002b) constituted by ancient coastlines and alignment of paleo-dunes, most of them now artificially levelled. the inner traces could be connected with the littoral deposits formed at lio maggiore and lio piccolo which are dated about 6500 yr bp (blake et al., 1988). the ancient coastlines are distributed over the whole district between rivers piave and sile. the general distribution of alignments shows at least four zones, each representing an advancing phase of the littoral, followed by an erosion event in all likelihood. the coastal stretch defines a cuspate delta, probably asymmetric, well developed in the area nowadays occupied by the piave mouth, but perhaps much more protruded into the sea, and lately interested by an erosion phase. the development of the older paleo-delta is ascribed to the upper atlantic, while during the transition atlanticsubboreal, the right portion of the piave paleo-delta might have started. the formation of the more recent cuspate delta, whose traces are scarce, seems to have started in the second part of the subboreal (bondesan et al., in press-a). mmaatteerriiaallss aanndd mmeetthhooddss the continuous core of palazzetto was collected using a mechanic sampler, down to a depth of 21.71 m. the lithology of sediments is indicated at the left side of the diagrams, according to the troels-smith system. we selected 42 samples (2 cm3). the uppermost 80 cm (agricultural soil and sand) and the sediments from 6.96 m to 10.10 m and from 18.49 m to 19.39 m (sands) were not considered because unsuitable for pollen conservation. tablets of a known concentration of lycopodium spores were added to each samples prior to preparation so that fossil pollen concentration could be estimated. samples were treated with hcl (37%), cold hf (50%) and boiling naoh (10%). a sieve of mesh of about 200 µm was employed to isolate macrofossil and epidermal fragments from peat sediments. in the end, samples were acetolysed. residues were mounted on slides, in glycerine. all samples were analysed to count pollen and spores of ferns, bryophytes, algae and fungi; epidermal fragments were only identified. identification and counting were made with a magnification of 400x and critical determination at 1000x. identification was aided by a modern pollen and spore reference collection, and illustrations and keys including reille (1992; 1998), punt (1976), punt & clarke (1980; 1981; 1984), punt et al. (1988) and moore et al. (1991). “saccate grains” indicates broken pollen grains of the pinaceae family, but their genus or species are indeterminable. type 303, is described by van geel et al. (1981). they do not identify it, but they report that it mainly occurs in the late glacial (younger dryas) and early holocene sediments. we record high values of type 303 in peat that was rich of mosses fragments; therefore we put forward the hypothesis that one/more members of bryophytes could produce it. studies are in progress. type 200 is described by van geel et al. (1989) and kuhry (1997). the zygospores of the zygnemataceae are described by van geel (1978), van geel & van der hammen (1978) and van geel et al. (1981). identification of some epidermal fragments was aided by a modern collection. pollen counting mostly continued until pollen sum (trees+shrubs+upland herbs) reached 100÷250 units, according to the pollen content of the sample. the percentage of helophytes and hydrophytes, of pterydophytes, of bryophytes, of algae, of fungi and of foraminifera remains, respectively, is calculated over the pollen sum added to each group’s total. unknown grains did not show the characteristic features of pollen grains; therefore they were not included in the pollen sum. indeterminable grains (degraded, corroded, broken, pyritized) have been counted, their percentage is calculated over the sum of all pollen grains (identified, indeterminable and hidden). the pollen diagrams were calculated and drawn using the programs tilia and tilia.graph (grimm, 1990). we present a pollen preservation diagram (fig. 3), a pollen and spore concentration diagram (fig. 4), a pollen and spore percentage synthetic diagram (fig. 5), a pollen percentage diagram of selected taxa (fig. 6) and a pollen percentage diagram of helophytes and hydrophytes (fig. 7). when terrestrial pollen sum didn’t reach 100 units, we have marked the sporomorphs findings with a plus sign in the diagrams. the occurrence of epidermal fragments has been indicated with circle signs. four 14c dates were obtained from sediment associated with a specific layer identified from the pollen diagrams (tab. 1). radiocarbon dating was conducted at the beta-analytic inc. miami – florida. tab. 1 radiocarbon dates from palazzetto core. lab. reference sample depth 14c age method (cm) (yr bp) beta 173728 76-80 500±70 standard beta 168127 581-609 6520±50 standard beta 168128 1323-1333 19850±120 standard beta 168129 2049-2059 21250±150 standard rreessuullttss we have analysed 42 samples from the palazzetto core (fig. 3), but 15 samples were virtually free of pollen (pollen sum<10 grains) and 8 samples were rather poor in pollen (pollen sum<100 grains). pollen concentration is generally low in the a. bondesan et al. 187 part of the core the pollen preservation is poor, with up to 40% indeterminable pollen, probably resulting from physical transport of the pollen grains in the silt sediments. grains infilled with crystals of pyrite (pyritized) are continuously present in the upper part of the core documenting chemically-reducing alluvial environment (berglund & ralska-jasieviczowa, 1986). the development of local and upland vegetation has not been continuously documented in the sequence because of the presence of sterile sand layers (see lithology), and because of the scarcity of pollen grains in fluvial sediments. nevertheless indicative local environments may be reconstructed from the following stratigraphical-pollen data to recognise transgressive trend of the coast line at the north of venice lagoon. the chronology of the sequence is based on radiocarbon dates (tab.1). hereafter the most important features of the pollen analysis are described. 2211..4444÷÷1188..1199 mm. the basal peat (20.59÷20.34 m) contains a high percentage of uplands herbs (nap) including poaceae (53% average), artemisia, that reaches its highest value for the entire record (12%), chenopodiaceae, asteroideae undiff. and thalictrum. trees and shrubs are represented by low percentage: pinus (6% average), betula, ephedra fragilis type, larix type, abies, fagus sylvatica type and acer campestre type. the local wetland vegetation is mostly represented by cyperaceae pollen (93% of helophytes+hydrophytes fig. 7) and by aerial fragments, roots and fruits of carex species. we also find pollen of lemna, potamogeton subg. p . type, nuphar, and sparganium emersum type. high percentage of algal spores (zygnema type) is recorded in this layer. the presence of mosses in the local environment is indicated by the highest value (67%) of spore percentage in the entire sequence and by many fragments of leaves and little stems. the dominant type of spores is type 303. upland local vegetation is dominated by populus (16%) that could occur in the area surrounding the depressions, among grassy vegetation of poaceae. the pollen and bryophytes concentrations decrease in the peat layer paleoenvironmental reconstruction from lgm ... fig. 4 pollen and spores concentration diagram of palazzetto core. fig. 3 pollen preservation in the sediment of palazzetto core (total pollen sum: trees, shrubs, upland and wetland herbs, indeterminable, hidden pollen grains). sequence: it reaches the value of about 100 x 103 grains/cm3 only at the depth of 20.34 m (peat) and at the depth of 5.84 m (organic clay) (fig. 4). we believe that the scarcity of pollen grains was caused by a fast rate of silt and clay sedimentation in the floodplain environment. in fact unsuitable conditions of preservation are unlikely because of the good state of the rare grains we found, almost from the bottom to the depth of 5.84 m and the percentage of indeterminable grains (degraded, corroded, broken and pyritized) surpassing 20% only in the sample at the depth of 13.00 m (fig. 3). in the upper 188 a. bondesan et al. fig. 5 pollen and spore percentage synthetic diagram of palazzetto core. at 18.34÷18.39 m but the pollen assemblage does not change. the fungal spore concentration increases. the dominant type is type 200. the occurrence of pollen in the next layers up to 13.84 m is very low. 1133..8844÷÷1122..8811 mm. nap continues to dominate the pollen assemblage. the higher value of total pollen concentration (60 x 103 grains/cm3) corresponds with a peat layer (13.18÷13.16 m). poaceae are the dominant taxon (maximum value 85%). cyperaceae’s percentage shows a declining trend. the sediments at the top contain the highest percentage of hydrophytes (61% of helophytes + hydrophytes). instead artemisia and chenopodiaceae percentages decrease. arboreal taxa are mostly represented by pinus (p. cembra, p. mugo/p. sylvestris) and “saccate grains”. populus and salix show increasing percentages, while alnus is rare. picea and castanea sativa type are recorded for the first time. 1122..8811÷÷1100..0000 mm. nap continues to dominate the pollen assemblage and poaceae are the dominant taxon: the highest concentration value corresponds to a layer of organic clay at the depth of 11.54÷11.52 m. cyperaceae pollen percentage increases. hydrophytes show lower concentration and percentage values if compared to the previous layers. we do not find any significant changes in the other herbaceous pollen taxa, as artemisia, chenopodiaceae, asteroideae undiff. and cichorioideae undiff. pinus undiff. prevails even if with low percentages; betula, picea, larix type, abies are present with only few pollen grains. 77..0000÷÷33..7766 mm. a 3 m thick layer of sand separates these layers by the previous ones. the pollen content of the samples from 7.00 m to 5.76 m is very low (<10 grains per slide). we have identified few pollen taxa: pinus undiff., picea, larix type, salix, poaceae and cyperaceae. the occurrence of 3 inner organic linings of ammonia beccarii at the depth of 6.20 m, is very interesting, mostly because of the poorness of samples. we have continuously found it from this layer up to the top of the core. the pollen assemblage of the organic clay samples (5.86÷5.78 m) is characterised by the dominance of nap as in the previous layers, but it shows some changes in pollen taxa distribution. some of the previously most important taxa decrease: helophytes and hydrophytes are rare, poaceae decrease to a percentage values of about 10%, chenopodiaceae pollen is abundant for the first time: it attains a maximum of 44%. new taxa of plumbaginaceae are found: limonium vulgare type a and armeria maritima type a and b, that include species living in salt marshes as l. narbonense miller. plumbaginaceae undiff. pollen attains its highest frequency in the core (7%). arboreal pollen does not dominate in the pollen assemblage but some taxa show their maximum concentration value in the core: quercus robur group, corylus, fagus sylvatica type, pinus undiff., “saccate grains”, betula. carpinus type firstly occurs. castanea sativa type (<1%) is continuously represented from here up to the top of the core with values ranging around 2-3%. the inner organic lining of ammonia beccarii (“other” in fig. 5) attains a maximum concentration value in the core. silty grey clay sediments constitute the upper layer and they are virtually barren of sporomorphs. 33..7766mm÷÷11..0088 mm. the pollen assemblages are characterised by: i) the dominance of ap; ii) the first notable increase of several broad-leaf trees taxa; iii) the contemporaneous presence of quercetum s.l. elements, of pinus (decreasing) and betula, and of picea, fagus and abies. ap percentage value attains 90% at the bottom of these layers, but it shows a declining trend in the upper layers. the palynological richness attains its maximum value of 19 arboreal pollen taxa and 14 herbaceous pollen taxa. riparian plants, such as alnus, populus and salix, show increased percentages. poaceae slightly increase from the bottom to the top. 189paleoenvironmental reconstruction from lgm ... there is a reduction of helophytes and hydrophytes. indeterminate grains (mechanically damaged) and “saccate grains” are continuously found with the highest concentration and percentage values at the top of the core. there is a notable reduction of pollen content at the top: total pollen concentration drops to 8 x 103 grains/cm3. ammonia beccarii inner organic linings are found in each sample. 11..0088÷÷00..8822 mm. the pollen concentration increases at the top of the core, but deciduous plants disappear except for populus and salix. helophytes and hydrophytes pollen prevail on the other taxa. the spores of pterydophytes and bryophytes are very abundant. we do not find pollen that indicates the nearby presence of human activities. iinntteerrpprreettaattiioonn ooff rreessuullttss the lithology of sediment, along with pollen and macrofossil records point to the fact that the sedimentation environment at the bottom of palazzetto core, changed from an open water stage (22.00÷21.00 m), probably with a high rate of sedimentation, to a mire stadium (20.49÷20.34 m), with carex species and brown mosses at 21,250±150 yr bp. the presence of a water table close to the surface or other geomorphological conditions, i.e. shallow closed depressions or lasting snow cover, are suggested by the ecological optimum of some carex species (c. ferruginea scop., c. limosa l., c. rostrata stokes), which is characterised by a good water availability (buffa & sburlino, 2001; bragazza, 1999). the assemblage of spores of zygnema type and aquatic taxa (lemna, potamogeton, callitriche, and nuphar) pollen points to the local occurrence of pools in some shallow depression of the mire. the conditions of sedimentation change significantly at the depth of 19.30 m. silt and sand layers indicate an active nearby fluvial system. in the upper peat layer (18.34÷18.39 m) the occurrence of fungal type 200 could be indicative of marked table fluctuations during the growing season and of relatively dry microhabitats in temporary desiccating bottoms of pools. the pollen concentration and assemblage are typical of a cold and dry climate, that corresponds to the radiocarbon dating results. the low pollen concentration found in the analysed sediments until 13.84 m could be linked to the high rate of sedimentation suggested by the radiocarbon dates. from the depth of 13.84 m the local conditions gradually change: the total pollen concentration increases in concomitance with the development of a new mire stadium (13.16÷13.18 m). initially high percentage and concentration values of aquatic plants pollen suggest that aquatic conditions prevail. poaceae (perhaps phragmites sp.) and cyperaceae stands, grow around the basin but they gradually fill it up, until the formation of a mire (13.16÷13.18 m). the lithology of sediments from 12.81 m to 7.00 m (roughly represented in this paper) suggests that the sedimentation environment changed many times, but we didn’t note significant changes in pollen associations. from the age of 6520±150 yr bp (6.09÷5.81 m), many records suggest local development of a lagoon environment. plumbaginaceae (limonium vulgare type a and armeria maritima type b include l. narbonense miller), poaceae, cheno-podiaceae and asteraceae asteroideae undiff. represent the local vegetation. we suppose that modern analogue could be found in pioneer vegetation of silt and silty sands, living in salt marshes of the lagoons in the northern adriatic coast. lymonium narbonense miller, spartina maritima (curtis) fernald and some species of chenopodiaceae form the association limonio narbonensis-spartinetum maritimae that changes in limonio narbonensispuccinellio festufig.6 pollen percentage diagram of selected taxa of palazzetto core. ciformis when the ground level increases (caniglia et al., 1997). pollen morphology does not allow any identification of spartina maritima (curtis) fernald or puccinellia palustris (seen.) hayek or different species of chenopodiaceae; therefore the stage of vegetation dynamics is not given to know. studies are in progress to recognise epidermal fragments of roots. the presence of ammonia beccarii inner organic linings is another important feature of the zone, because a. beccarii is the dominant taxon among the foraminifera that today are living in the water of venice lagoon (serandrei barbero et al., 2001). its occurrence is indicative of an open salt/brackish water environment too. upland vegetation abruptly changes: we note that pollen percentage of pinus is overtaken by pollen percentage of thermophilous broad-leaf plants. rizzi longo (1996) reviewed pollen records from friuli plain sequences. she underlies that pinus decreases during the passage from pre-boreal to boreal period and the association of oaks and other broad-leaf trees grows. in the plain belt mixed oak forest dominates until historical times. radiocarbon dating and the results of our preliminary pollen analysis is in full accordance with these data. from the depth of 3.76 m an open water environment covered the area and upland forest vegetation was probably near the banks: riparian plants, such as alnus, salix and populus lived near the basin, mixed oak forest covered the surrounding areas. the low percentage of cyperaceae, aquatic plant pollen, and fresh-water algal spore, and the constant presence of ammonia beccarii indicate a salt/brackish quality of water. dominance of quercetum s.l. decreases towards the top of the core; castanea and corylus pollen are constantly present and do not change their trends. these are common features of friuli plains pollen diagrams and they are dated to historical times (rizzi longo, 1996). drastic changes in pollen association suggest the development of new environmental conditions at the age of 500÷70 yr bp (cal ad 1400 to 1450). the disappearance of tree pollen and the consistent presence of pterydophytes spores could be the signs of the late middle age human activity in the area (cagnin, 2000). the presence of type 200 fungal spore indicates that the area was subject to marked fluctuations of the water table, during the growing season. the decline in ammonia beccarii and increased frequencies of freshwater plants suggest a lower influence of seawater. ccoonncclluuddiinngg rreemmaarrkkss the results from radiocarbon dating suggest that the palazzetto sequence spans the lgm and the historical times. the depositions of silt and sand layers interrupted the pollen and lithological sequence, and therefore the history of the local environment is fragmented. probably the studies in progress of the other two cores (ca’ fornera and fiorentina) will add further elements to the history of the area. cyperaceae peat layers were deposited at the bottom of the core during the end of the last glacial period. these layers could be correlated with similar peat layers from the veneto and friuli plain, already described by other authors (bortolami et al., 1977; mullenders et al., 1996; serandrei barbero et al., 2001; bondesan et al., 2002b): studies are in progress. four events of fluvial sedimentation, attributed to the piave river, follow the deposition of the basal peats at the depth of about 19 m, 17.5 m, 15 m and 11 m. they occurred before the beginning of the holocene. the last important fluvial sedimentation (10÷7 m) occurs before the development of brackish/salt communities in the area, at the age of ca. 6520±150 yr bp. pollen and spore association at the depth of ca. 6 m, documents the development of a lagoon environment, connected to the flandrian transgression not yet described in the san donà di piave plain. in the nearby venice lagoon, first lagoon sediments after the flandrian transgression have been dated to 5090±100 yr bp by serandrei barbero et al. (2001). the geochronological dating and pollen analysis of the three cores will let us verify the dynamics of the ingression of the lagoon. aacckknnoowwlleeddggeemmeennttss we would like to thank the anonymous referees for their comments and useful suggestions on a previous draft and dr. alessandra asioli for the identification of ammonia beccari inner organic lining. we thank dr. paolo mozzi for the given help in core analysis. 190 a. bondesan et al. fig. 7 helophytes and hydrophytes percentage diagram of palazzetto core. rreeffeerreenncceess berglund b.e. & ralska-jasiewiczowa m. (1986) pollen analysis and pollen diagrams. in: handbook of holocene palaeoecology and palaeohydrology. berglund b. e. (ed.), john wiley & sons, chicester, p. 455-484. blake h., bondesan a., favero v., finzi e. & salvatori s. (1988) cittanova heraclia 1987: risultati preliminari delle indagini geomorfologiche e paleogeografiche, quad. arch. del veneto, 44, p. 112135. bondesan a. 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(1996) analyses polliniques de sondages a venise (ve-i, ve-i bis, ve-ii), in "pleistocene palynostratigraphy". gullentips f. (ed), aardk. mededel., 77, p. 87-117. murst (1997) carta geomorfologica della pianura padana, 3 fogli, scala 1:250.000, s.el.ca., firenze. punt w. (1976) the northwest european pollen flora, i. rev. palaeobot. palynol., 1177,, 1199 e 2211. elsevier, amsterdam, pp. 145. punt w., blackmore s. & clarke g.c.s. (1988) the northwest european pollen flora, v. rev. palaeobot. palynol., 5577, elsevier, amsterdam, pp. 154. punt w. & clarke g.c.s. (1980) the northwest european pollen flora, ii. rev. palaeobot. palynol., 2266, elsevier, amsterdam, pp. 265. punt w. & clarke g.c.s. (1981) the northwest european pollen flora, iii. rev. palaeobot. palynol., 3333, elsevier, amsterdam, pp. 138. punt w. & clarke g.c.s. (1984) the northwest european pollen flora, iv. rev. palaeobot. palynol., 4422, elsevier, amsterdam, pp. 369. reille m. 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(1980-1981) a palaeoecological study of upper late glacial and holocene sequence from “de borchert”, the netherlands, rev. palaeobot. palynol., 3311, p. 367448. van geel b., coope g.r. & van der hammen t. (1989) palaecology and stratigraphy of the lateglacial type section at usselo (the netherlands), rev. palaeobot. palynol., 6600, p. 25-129. van geel b. & van der hammen t. (1978) zygnemataceae in quaternary colombian sediments, rev. palaeobot. palynol., 2255, p. 377-392. 192 a. bondesan et al. imp.tropeano& depositi carbonatici infrapleistocenici di tipo foramol in sistemi di scarpata (salento italia meridionale) marcello tropeano1, luigi spalluto2, massimo moretti2-3, piero pieri2-3 & luisa sabato2 1dipartimento di scienze geologiche, università della basilicata, campus di macchia romana, 85100, potenza <tropeano@unibas.it> 2dipartimento di geologia e geofisica, università di bari, via orabona 4, 70125, bari <l.spalluto@geo.uniba.it> <m.moretti@geo.uniba.it> <p.pieri@geo.uniba.it> <l.sabato@geo.uniba.it> 3centro interdipartimentale di ricerca per la valutazione e mitigazione del rischio sismico e vulcanico, università di bari, palazzo di scienze della terra, via orabona 4, 70125, bari riassunto: tropeano m., spalluto l., moretti m., pieri p. & sabato l., depositi carbonatici infrapleistocenici di tipo foramol in sistemi di scarpata (salento italia meridionale). it issn 0394-3356, 2004. la penisola salentina, fra otranto e santa maria di leuca, termina verso mare con un articolato e ripido pendio roccioso, che raccorda la porzione sommitale della regione (le serre salentine, una sorta di modesto altopiano costituito da blandi rilievi ed ampie depressioni orientati quasi ortogonalmente alla costa) al canale d'otranto nel mar ionio. il pendio roccioso è costituito da carbonati appartenenti a differenti unità stratigrafiche discordanti fra loro, la cui età è compresa fra il cretaceo ed il quaternario. fra questi depositi sono stati studiati i più giovani, infrapleistocenici, presenti nella parte bassa del pendio roccioso fino al livello del mare, attribuiti in letteratura alle calcareniti del salento e ritenuti, prima di questo lavoro, di ambiente costiero. questi depositi carbonatici di tipo foramol affiorano in maniera discontinua, presentano spessori variabili da pochi metri fino a diverse decine di metri e corrispondono a piccoli corpi isolati sviluppatisi in alcune brusche rientranze del pendio. in particolare, a porto miggiano (santa cesarea) ed a castro marina le successioni sono caratterizzate da lunghi clinoformi interrotti da nicchie di distacco di frane sottomarine evolutesi in piccoli canali effimeri. le nicchie di distacco sono cicatrizzate da backset mentre i canali sono riempiti o da depositi simili a quelli incisi o, caoticamente, dagli stessi materiali in frana. depositi di frana (slumps) ed altre soft-sediment deformation structures si riconoscono soprattutto nella parte bassa delle successioni, dove i clinoformi diminuiscono asintoticamente il loro angolo. l'insieme dei dati sedimentologici porta ad interpretare queste calcareniti come depositi di scarpata e base di scarpata sottomarina, alimentati sia dai sistemi carbonatici di mare sottile presenti fra le serre che da produzione lungo il pendio. questi sistemi si sviluppavano in indentazioni del pendio e costituivano piccoli ed isolati aprons di profondità non elevata. l'interpretazione qui proposta porta a rivedere sia l'attribuzione formazionale dei depositi in oggetto sia le ipotesi circa l'evoluzione pleistocenica del salento. si suggerisce infatti di attribuire i depositi studiati alla formazione della calcarenite di gravina, nota soprattutto nell'area delle murge come l'unità che segna la fase di subsidenza dell'avampaese apulo indotta dalla propagazione verso est dell'orogene sudappenninico; inoltre, la posizione nella parte bassa del pendio dei depositi studiati, a differenza di quanto proposto in precedenza in letteratura, non indicherebbe una fase di stazionamento del mare lungo il pendio dopo un'iniziale fase di sollevamento infrapleistocenica della regione. il sollevamento sarebbe avvenuto solo successivamente, così come evidenziato dalla presenza di una serie di terrazzi marini medio-suprapleistocenici riconosciuti nell'area salentina da altri autori a partire da quote superiori rispetto a quelle di affioramento dei depositi studiati. abstract: tropeano m., spalluto l., moretti m., pieri p. & sabato l., lower pleistocene foramol-type carbonate deposits in slope systems (salento southern italy). it issn 0394-3356, 2004. along the eastern salento coast (southern italy), cretaceous to quaternary carbonates crop out on a 100 m high escarpment that connects a wide and relatively flat area to the otranto strait (ionian sea). along the escarpment, faulted and tilted cretaceous and eocene limestones record deposition in shallow-marine and marginal carbonate environments. younger carbonates disconformably overlie this substratum and they formed when the region was partially submerged. accordingly, priabonian to messinian carbonates which crop out along the escarpment were interpreted as slope deposits linked to reef systems developed on the margin of the top area, while lower pleistocene carbonates cropping out at the base of the same escarpment were considered coastal in origin and formed during the uplift of the region. stratigraphic and sedimentologic studies carried out on these lower pleistocene carbonates demonstrate that also these deposits should be considered as slope deposits. the studied carbonates are foramol-type ones and discontinuously crop out along the lower part of the escarpment. they show a variable thickness (from a few meters up to several tens) and often exhibit a fan morphology; they correspond to small isolated bodies (up to a few km2 wide) developed in some indentations of the escarpment, and are composed of coarse skeletal grains mainly deposited via slumpings or grain flows. successions are characterized by long clinobeds cut by slump scars downward passing to gullies; backsets, slumps and chaotic deposits fill these erosional features. clinobeds are alternatively made up of molechfor and rodhalgal facies which respectively record resedimentation by grain flows of shallow marine carbonates developed on top of the region and along-slope carbonate production. depositional systems correspond to small shallow-marine aprons whose discontinuous distribution along the escarpment (inside indentations) should be considered an original feature. the idea that these deposits record the sicilian sea-level along the escarpment should be abandoned as they are not coastal deposits. the studied deposits should be correlated to the calcarenite di gravina formation which in other areas of the apulian foreland (which the salento region belongs to) are considered as the deposits linked to the subsidence induced by the estward migration of the southapennines orogenic system. the quaternary uplift of the salento region should be begun after the deposition of the studied slope deposits, as indicated also by a series of middle-upper pleistocene marine terraces which start at heights higher than those ones of the studied deposits. parole chiave: carbonati di tipo foramol; depositi di scarpata; pleistocene inferiore; salento; italia meridionale. keywords: foramol-type carbonates; slope deposits; early pleistocene; salento; southern italy. il quaternario italian journal of quaternary sciences 17(2/2), 2004, 537-546 538 m. tropeano et al. 1. introduzione in puglia, principalmente nelle murge e nel salento, affiorano diffusamente carbonati plio-pleistocenici formatisi in contesti ambientali riconducibili a mare sottile (ciaranfi et al., 1988). questi carbonati, di ambiente temperato (pieri, 1975) e con caratteri di tipo foramol (tropeano, 1994a; 1994b), si deponevano sull'avampaese apulo quando la regione, caratterizzata da un esteso ed articolato sistema di alti e bassi morfostrutturali, per progressiva subsidenza evolveva da area emersa a vasto arcipelago (tropeano et al., 2002a). i caratteri morfostrutturali del substrato, dovuti sia all'evoluzione tettonica terziaria dell'avampaese (pieri, 1980; iannone & pieri, 1982; tozzi, 1993; festa, 2003) sia, in parte, a tettonica sinsedimentaria (pieri et al., 1997), determinavano lo sviluppo di differenti sistemi deposizionali e facies nei diversi contesti di sedimentazione incontrati dalla trasgressione indotta dalla subsidenza (iannone & pieri, 1979). in pratica si sviluppava sedimentazione carbonatica sia nei bracci di mare poco profondi che separavano gli alti morfostrutturali, sia lungo i versanti di questi ultimi (isole in via di sommersione), sia sulla loro sommità (banchi) quando gli alti venivano annegati (tropeano & sabato, 2000). i differenti sistemi deposizionali evolvevano su un substrato roccioso carbonatico fagliato, ed i loro caratteri erano determinati sia dalla alternanza dei bassi e degli alti morfostrutturali sia, sui versanti di questi ultimi, dalla spaziatura delle faglie e dalla entità dei loro rigetti verticali. se i versanti erano costituiti da estesi blocchi strutturati da faglie a piccolo rigetto, si sviluppavano rampe carbonatiche a debole pendio, caratterizzate da sedimentazione subtidale e rari corpi di spiaggia (tropeano & sabato, 2000); se i versanti presentavano un pendio più pronunciato, corrispondente ad un esteso blocco roccioso tiltato o ad un substrato roccioso strutturato da faglie molto ravvicinate, si sviluppavano sistemi deposizionali caratterizzati da corpi sigmoidali di ambiente costiero (con geometrie tipo gilbert) passanti distalmente in modo rapido ad ambienti di offshore (pomar & tropeano, 2001); se i versanti erano strutturati a gradinata da faglie con rigetti decametrici, i sistemi deposizionali a ridosso delle strutture erano caratterizzati da depositi di falesia a volte associati a delta ghiaiosi (sabato, 1996; tropeano & sabato, 2000). nelle depressioni, invece, si sviluppavano sistemi deposizionali relativi ad aree di canale o di golfo, sia protette rispetto al moto ondoso, talvolta con sedimentazione di tipo salmastro, sia aperte rispetto al moto ondoso (iannone & pieri, 1979; d'alessandro et al., 2004). sulla sommità dei rilievi, una volta sommersi, si sviluppavano infine piccole piattaforme carbonatiche isolate, caratterizzate da sedimentazione subtidale (tropeano, 1994a; 1994b). nel salento meridionale, lungo la costa che si affaccia sul canale d'otranto (fra otranto e santa maria di leuca), alcune delle successioni carbonatiche infrapleistoceniche affioranti sono state recentemente attribuite a sistemi deposizionali di scarpata e di base di scarpata (tropeano et al. 2000; 2002b), differenti quindi rispetto ai sistemi noti in letteratura e fin qui ricordati. il presente lavoro, a carattere preliminare, intende offrire alcuni elementi interpretativi di questi nuovi sistemi deposizionali riconosciuti, che portano a proporre un quadro paleogeografico locale differente da quello noto in letteratura, e ad avanzare alcune considerazioni di carattere neotettonico e formazionale sull'area salentina investigata. 2. inquadramento geologico il salento rappresenta la porzione meridionale dell'avampaese apulo emerso (fig. 1a) e, come le altre porzioni dell'avampaese, è costituito in affioramento da una potente successione carbonatica mesozoica coperta, in maniera discontinua, da sottili unità più recenti a prevalente costituzione carbonatica (palmentola, 1987; ricchetti et al., 1988). lo studio è stato condotto nella parte sudorientale della penisola salentina, che rappresenta, sotto il profilo morfologico, una sorta di modesto altopiano limitato ad e (verso mare) da una scarpata a luoghi fortemente acclive. l’altopiano è caratterizzato dall'alternanza di blandi rilievi (le serre salentine), con elevazioni massime di circa 190 m rispetto all'attuale livello del mare, e di estese e poco profonde depressioni, le cui quote raggiungono circa 120 m sul livello del mare. questo sistema morfostrutturale, con orientazione nno-sse, ha condizionato lo sviluppo delle unità marine più recenti, che si sono deposte e/o conservate nelle aree depresse prima del sollevamento quaternario della regione (martinis, 1962; palmentola & vignola, 1980) (fig. 1a). la fascia costiera che si affaccia sul canale d'otranto (fra otranto e santa maria di leuca) è orientata quasi ortogonalmente al sistema di rilievi e depressioni delle serre e qui, come accennato, l’altopiano termina verso mare con un articolato e ripido pendio roccioso che raccorda bruscamente l'area delle serre all'attuale piattaforma continentale (budillon & aiello, 1999). il pendio roccioso è costituito in affioramento da carbonati appartenenti a differenti unità stratigrafiche discordanti fra loro e la cui età è compresa fra il cretaceo ed il quaternario. in sintesi, le unità carbonatiche supracretaciche e medioeoceniche rappresentano il substrato deformato su cui si sono addossate unità più giovani; infatti il pendio roccioso attualmente esposto ricorda per lunghi tratti il pendio sommerso che avrebbe caratterizzato la regione dal priaboniano al messiniano e sul quale si sedimentavano i depositi di scarpata relativi ai coevi sistemi deposizionali carbonatici di scogliera che si sviluppavano sul margine della regione salentina (bosellini et al., 1999). per quanto riguarda le unità più giovani, plio-pleistoceniche, affioranti nella porzione meridionale del salento e in parte lungo lo stesso pendio roccioso, queste sono state attribuite a differenti unità formazionali (formazione di leuca, formazione di uggiano la chiesa, calcareniti del salento) e la loro età ed il loro significato ambientale e paleogeografico sono tuttora oggetto di dibattito (a titolo di esempio, la formazione di uggiano la chiesa è considerata di età pliocene medio-superiore da bossio et al., 1987c, di età pliocene medio-santerniano da bossio et al., 1997, e di età pliocene superiore da bosellini et al., 1999). in particolare, le calcareniti del salento affioranti nella parte bassa del pendio roccioso ed oggetto del presente lavoro (fig. 1b) sono state genericamente descritte nei lavori più recenti come depositi costieri (bosellini et al., 1999), e la loro posizione nella parte bassa del pendio è stata addebitata ad uno stazionamento del mare nel siciliano, successivo quindi ad una fase infrapleistocenica (emiliana) di sollevamento della regione (bossio et al., 1987a, 1987b). depositi carbonatici di età relativamente più antica (formazione di uggiano la chiesa) sono invece segnalati sul rilievo ed occupano ampie aree depresse delle serre (fig. 1b). questa ricostruzione non sembra però coerente con alcuni studi di carattere paleoecologico e geomorfologico secondo i quali i depositi carbonatici infrapleistocenici del porto di castro (una delle tipiche località di affiora539depositi carbonatici ... mento delle calcareniti del salento lungo il pendio roccioso oggetto di studio) andrebbero riferiti ad ambienti profondi almeno 100 m, quando anche la parte sommitale della regione salentina era ricoperta da una lama d'acqua non inferiore alla decina di metri, e sarebbero da attribuire sia all'emiliano che al siciliano (taddei ruggiero, 1983; 1993; 1994). per quanto riguarda invece la successione calcarenitica di porto miggiano (anch'essa affiorante nella parte bassa del pendio ed oggetto di questo studio), già attribuita al calabriano da rossi & ungaro (1969), questa è considerata di età siciliana da bossio et al. (1987b) e, nella sua porzione più elevata, di età tirreniana da zezza (1983). fig. 1 a) carta geologica schematica della porzione meridionale della penisola salentina. si noti la distribuzione delle unità plio-pleistoceniche rispetto a quelle più antiche, che rappresentano i rilievi delle serre salentine. b) carta geologica schematica dell’area studiata. si noti: la posizione alla base della scarpata dei depositi attribuiti in letteratura alle calcareniti del salento; la loro ubicazione rispetto alle faglie attive durante la sedimentazione; la loro distribuzione in relazione a quella dei depositi attribuiti in letteratura alla formazione di uggiano la chiesa (da bossio et al., 1997, semplificata). a) geological sketch map of the southern part of the salento peninsula (see the insect for the location in italy). the plio-pleistocene deposits fill morphostructural depressions between older rocks. b) geological sketch map of the study area. the studied deposits (calcareniti del salento) rest at the base of a rocky slope. see both their location respect to sinsedimentary faults and distribution of the uggiano la chiesa formation at the top of the relief (after bossio et al., 1997, modified). 540 per quanto riguarda infine gli aspetti di tipo strutturale, i principali lineamenti tettonici riconosciuti nell'area interessano tutti i termini affioranti lungo il pendio roccioso e presentano rigetti variabili da qualche metro fino ad oltre 200 m (martinis, 1962; 1967). rispetto alle successioni infrapleistoceniche oggetto di studio si può quindi riconoscere un'attività pre-, sin-, e post-deposizionale di queste strutture (moretti, 1997). le strutture riconosciute sono essenzialmente faglie subverticali orientate nno-sse e no-se; sono presenti inoltre sia direttrici trasversali alle precedenti che orientate n-s (sulla costa fra porto badisco e otranto, santa cesarea terme e presso tiggiano martinis, 1962). la maggior parte di queste faglie (soprattutto nel settore sud-occidentale) è di tipo trascorrente con successivi e/o alternati movimenti obliqui e di tipo normale (tozzi, 1993). 3. i depositi carbonatici infrapleistocenici di santa cesarea terme e castro marina nella parte bassa del pendio roccioso che si affaccia sul canale d'otranto, affiorano in maniera discontinua alcune successioni attribuite alla formazione delle calcareniti del salento e ritenute in letteratura di età siciliana (bossio et al., 1997; bosellini et al., 1999). localmente, questi affioramenti non superano i pochi chilometri quadrati di estensione e raggiungono spessori massimi di alcune decine di metri. vengono di seguito descritte ed interpretate le successioni affioranti in maniera spettacolare nei pressi di santa cesarea terme (porto miggiano) e di castro marina, entrambe già oggetto in precedenza di alcuni lavori di dettaglio (rossi & ungaro, 1969; taddei ruggiero, 1983; 1993; 1994; zezza, 1983; bossio et al., 1987a; 1987b). in entrambe le località le successioni si sviluppano in una brusca indentazione del pendio e sono limitate da faglie subverticali; in entrambi i casi è stata evidenziata una attività tettonica sinsedimentaria delle faglie (martinis, 1967; moretti, 1997). 3.1. descrizione le successioni infrapleistoceniche studiate presentano spessori variabili fino ad un massimo di circa 40-50 m e si addossano, in discordanza lungo pendio, sulle unità più antiche. uno dei caratteri interni più evidenti è la diffusa presenza di lunghi clinoformi, il cui angolo di inclinazione varia fino ad un massimo di 25°30°; l'immersione dei clinoformi è verso mare, coerente con l'originale orientazione del paleopendio roccioso, con tendenza ad orizzontalizzarsi asintoticamente verso l'attuale falesia costiera (fig. 2). i clinoformi sono rappresentati da strati, anche sottili, e banchi di spessore superiore al metro e sono costituiti da biocalcareniti, biocalciruditi e, subordinatamente, da calcisiltiti e rari orizzonti argillosi di colore verdastro; sono generalmente bioturbati, con aumento della bioturbazione verso il tetto degli strati. le litofacies riconosciute sono costituite da grainstones e packstones bioclastici ad alghe rosse, briozoi, echinidi, brachiopodi, rari coralli solitari e bivalvi, frequentemente in frammenti. in sezione sottile si riconoscono sia facies ricche in foraminiferi bentonici che facies ricche in foraminiferi planctonici, queste ultime associate a briozoi ed alghe rosse (fig. 3). gli strati presentano rare strutture interne, in genere laminazioni piane (o fantasmi di laminazione) parallele ai clinoformi. le superfici di strato, in tagli paralleli al pendio, appaiono ondulate a grande scala simulando strutture tipo hummocky di ampiezza dell'ordine della decina di metri. i clinoformi sono a volte tagliati da nette superfici erosive canalizzate (con canali di ampiezza di alcuni metri, pareti molto acclivi fino a subverticali e fondo inclinato verso mare) che passano lateralmente a superfici di strato. le forme canalizzate immergono verso mare, spesso con orientazione leggermente differente rispetto a quella dei foreset sottostanti tagliati dall'erosione. le facies di riempimento dei canali sono generalmente simili a quelle dei depositi incisi e, allontanandosi dai canali, le facies a contatto a letto ed a tetto delle superfici erosive non sono distinguibili. in alcuni casi però il riempimento dei canali presenta una complessa stratificazione incrociata, e, più raramente, è costituito da grossi intraclasti (di diametro fino a 50 cm) immersi in una matrice grossolana caotica (fig. 4); la morfologia degli intraclasti indica che la loro messa in posto è avvenuta allo stato plastico o semiconsolidato. inoltre, lungo pendio, sono state osservate strutture tipo backset impostatesi in presenza di brusche variazioni di pendenza delle superfici di appoggio del banco considerato (particolare della fig. 5). a diverse altezze nella successione, e comunque in affioramenti posti alla base del pendio, sono inoltre presenti strutture tipo slump in orizzonti deformati dello spessore di almeno 2-3 m (fig. 6). morfologicamente le strutture sono rappresentate da pieghe asimmetriche, thrusts con chiare superfici di decollement e faglie inverse, piem. tropeano et al. fig. 2 il piede delle calcareniti clinostratificate a porto miggiano toe of the clinobeds. porto miggiano locality. 541 ghe a scatola e strutture imbricate che interessano strati calcarenitici a differente granulometria (moretti, 1997). sono state osservate anche altre soft-sediment deformation structures come: intrusioni di sedimento liquefatto, load-casts e flame structures (moretti, 1997). le intrusioni di sedimento liquefatto (silt ben selezionato e finissimo) sono rappresentate da forme a "pera" od "imbuto" cioé molto strette verso il basso e svasate fino quasi ad orizzontali verso l'alto. le load-casts e le flame structures si rinvengono a vari livelli e sono rappresentate da ondulazioni del contatto fra calcareniti a diversa granulometria. le ondulazioni nella laminazione simulano larghi movimenti verso il basso (load-casts) e strette vie di fuga verso l'alto (flame structures). a luoghi la laminazione originaria risulta troncata da flussi provenienti dal basso. 3.2. interpretazione le facies bioclastiche che caratterizzano gli affioramenti descritti sono riconducibili a sistemi carbonatici di tipo foramol, con associazioni sia di tipo molechfor che di tipo rodhalgal (sensu carannate et al., 1988). in particolare, uno studio condotto da taddei ruggiero (1983) sui foraminiferi planctonici presenti in un campione significativo prelevato dalla successione di castro marina, indica che i sistemi si sviluppavano in climi temperato-temperato caldi non dissimili da quelli del mediterraneo attuale. non è possibile però ricondurre i caratteri stratigrafici e sedimentologici delle successioni studiate ai sistemi carbonatici di tipo foramol descritti per successioni parzialmente coeve affioranti nello stesso avampaese apulo (si veda il paragrafo introduttivo del presente lavoro). i banchi clinostratificati, notevolmente sviluppati in lunghezza e con appoggio asintotico nella parte bassa (troncato dalla falesia attuale), e la presenza di slumps indicano infatti che la sedimentazione delle successioni carbonatiche infrapleistoceniche di castro marina e di porto miggiano avveniva lungo un pendio sottomarino ed al suo piede. i lunghi clinoformi non sono sempre continui lateralmente per la presenza di forme erosive canalizzate che possono essere interpretate come nicchie di distacco di frane sottomarine (slump scars) evolutesi lungo pendio in depositi carbonatici ... fig. 3 esempi di facies riconosciute in sezione sottile: a) grainstone a foraminiferi bentonici e frammenti di bivalvi, alghe rosse ed echinidi; b) packstone con alghe rosse, briozoi e rari foraminiferi; c) packstone a briozoi e foraminiferi planctonici. thin sections of some representative facies: a) grainstone with bentic foraminifers and fragments of bivalvs, red algae ed echinoids; b) packstone with red algae, bryozoans and rare foraminifers; c) packstone with bryozoans and planctonic foraminifers. fig. 4 canale erosivo lungo le calcareniti clinostratificate; la freccia bianca indica un grosso intraclasto nel riempimento del canale. la scala è fornita dalle due persone in alto. località porto miggiano. erosional channel (gully) along clinobeds; the white arrow indicates a big intraclast in the infilling deposits. two people on top for scale. porto miggiano locality. 542 stretti e ripidi canali effimeri (gullies) causati dallo scorrimento della frana su materiali poco consolidati. nella parte inferiore del pendio, il riempimento dei canali era opera dello stesso materiale in frana, sia come deposito caotico a grossi intraclasti (debris flows) sia come classico deposito da slump (strati contorti). in alcuni casi l'erosione ed il riempimento multiplo dei canali determinano la presenza di una stratificazione incrociata molto complessa ma confinata lateralmente. per quanto riguarda le strutture tipo grandi hummocky, queste forme rappresentano un effetto di prospettiva su tagli paralleli al pendio di banchi inclinati a morfologia ondulata; l'ondulazione rappresenta zone di maggiore o minore accumulo dei sedimenti lungo pendio; non si tratta quindi di forme di fondo trattive ma di rilievi e depressioni orientati parallelamente al pendio in un m. tropeano et al. fig. 5 calcareniti clinostratificate a castro. nel particolare è evidenziato un backset. clinobedded calcarenites at castro locality. see the backset in the insect. materasso continuo ed aggradante di sedimenti. la presenza di backset lungo i clinoformi e la cicatrizzazione delle nicchie e dei canali da parte di sedimenti simili a quelli erosi, indicherebbe l'attività di flussi sedimentari tipo grain flow; questi processi erano episodici, come indicato dalla diffusa bioturbazione che aumenta nella parte alta degli strati e dei banchi. infine, le strutture deformative riconosciute oltre gli slumps, indicano che le facies in cui si sviluppavano erano poste nella parte bassa del pendio, in quanto intrusioni di sedimento, load casts e flames si possono originare per processi di liquefazione e fluidificazione indotti da aumento repentino del carico litostatico (overloading) in conseguenza di episodi di sedimentazione di massa. 4. discussione 4.1 sistemi deposizionali ed ipotesi paleogeografiche in base ai caratteri descritti e alla loro interpretazione si ritiene che le successioni studiate rappresentino il prodotto di una sedimentazione carbonatica di tipo foramol in ambienti di scarpata e di base di scarpata. ricordando che durante il pleistocene inferiore il sistema a blandi rilievi e depressioni delle serre salentine ed il pendio di raccordo verso il canale d'otranto erano già presenti, e che il sistema governava la distribuzione di aree emerse e sommerse del salento meridionale, può essere proposta una ipotesi paleogeografica relativa all'origine dei depositi studiati, coerente con le osservazioni sedimentologiche effettuate sulle successioni. le aree sommerse del sistema delle serre salentine, sede di attiva sedimentazione carbonatica di mare sottile, erano rappresentate da zone più o meno profonde (golfi o ampi canali che si alternavano a banchi o altofondi) che passavano verso il pendio a canyon sottomarini in roccia. tali canyon sono tuttora riconoscibili come elementi morfologici del pendio roccioso in indentazioni della falesia e sono impostati o sulla prosecuzione di alcune delle blande depressioni delle serre o in coincidenza di faglie ad attività sinsedimentaria. eventi di alta energia, come correnti di tempesta o di amplificazione tidale nei canali, innescavano il trasporto lungo il pendio (prevalentemente lungo i canyon) dei sedimenti carbonatici prodottisi in mare sottile (facies carbonatiche tipo molechfor) e la loro risedimentazione, nella parte medio-bassa dei canyon e al piede del pendio roccioso, in forma di accumuli sottomarini isolati fra loro (fig. 7). lungo pendio era attiva anche una factory di mare relativamente più profondo che concorreva allo sviluppo delle successioni (facies carbonatiche tipo rodhalgal). gli accumuli sedimentari lungo pendio erano però gravitativamente instabili e soggetti a frane sotto543depositi carbonatici ... fig. 6 esempio di slump nella parte alta della successione; il martello (freccia) come scala. località porto miggiano. slump in the upper part of the succession; the hammer (arrow) for scale. porto miggiano locality. fig. 7 schema paleogeografico dei sistemi di sedimentazione di scarpata e di base scarpata durante il pleistocene inferiore. palaeogeographic sketch of slope and base-of-slope sedimentation during early pleistocene. marine; la cicatrizzazione delle nicchie di distacco giustifica la presenza di discordanze interne riconosciute nelle successioni già da rossi & ungaro (1969). considerando regionalmente la geometria e la posizione delle aree di affioramento, la forma in pianta dei depositi ricorda quella di piccole conoidi sottomarine. queste risultano ubicate in corrispondenza di brusche rientranze del pendio roccioso e andrebbero considerate come una testimonianza della originale distribuzione dei sedimenti infrapleistocenici alla base del paleopendio sottomarino piuttosto che lembi residui di una originale copertura più ampia. l'accumulo lungo pendio, e non solo alla sua base, e la continuità laterale degli strati, nonostante la loro ondulazione ed il fatto di essere incisi da frane e canali effimeri, porta ad interpretare i sistemi deposizionali come apron isolati di piccole dimensioni. si trattava di sistemi deposizionali di relativa bassa profondità, fra 100 e 150 m, in buon accordo con quanto sostenuto su basi paleoecologiche da taddei ruggiero (1983; 1993) 4.2 considerazioni formazionali e neotettoniche l'interpretazione ambientale e paleogeografica qui proposta impone una revisione biostratigrafica delle successioni studiate, in quanto parte dei depositi attribuiti alla formazione di uggiano la chiesa, posti nelle blande depressioni delle serre e considerati mediopliocenico-santerniani (bossio et al., 1997), e quelli attribuiti alle calcareniti del salento, posti alla base del pendio e ritenuti di età siciliana (bossio et al., 1987a; 1987b), dovrebbero essere coevi. questa ipotesi è coerente con la distribuzione dei depositi infrapleistocenici in aree esterne a quella studiata, ed in particolare nella porzione sudoccidentale della penisola salentina, dove si può notare che gli affioramenti posti in corrispondenza dell'attuale livello del mare sono fisicamente continui con quelli posti nelle parti alte della penisola (martinis, 1970; bossio et al. 1997). in questo settore infatti le depressioni morfostrutturali presenti nella parte alta del rilievo si raccordano al mare con un pendio a gradiente costante e costituivano il substrato di sistemi di rampa carbonatica i cui prodotti sedimentari vengono attribuiti ad una unica unità formazionale (calcareniti del salento, come nell'area di tricase in: bossio et al., 1997). se in queste aree gli affioramenti infrapleistocenici affioranti a livello del mare vengono correlati fisicamente a quelli affioranti nelle parti alte della penisola (fino a quote di circa 110-120 m sul livello del mare), anche nell'area considerata nel presente lavoro, in base all'interpretazione ambientale proposta, non sussisterebbe più la necessità di distinguere dal punto di vista formazionale i depositi posti alla base del pendio da quelli affioranti nelle serre. inoltre, a livello regionale, entrambe le unità (calcareniti del salento e formazione di uggiano la chiesa), o parti di esse, sarebbero da attribuire alla formazione della calcarenite di gravina (sensu iannone & pieri, 1979), la cui età nell'area delle murge, dove fu istituita da azzaroli (1968), varia dal pliocene medio al pleistocene inferiore (ciaranfi et al., 1988), un intervallo di tempo compatibile con i depositi salentini in oggetto (si veda anche ciaranfi et al., 1993). anche il significato sedimentario dei depositi studiati sarebbe simile a quello assunto dalla formazione della calcarenite di gravina nelle murge, dove l'unità registra una significativa ingressione marina sull'avampaese apulo (iannone & pieri, 1982). la revisione sedimentologica dei depositi infrapleistocenici descritti in questo lavoro permette di affermare infatti che anche durante il siciliano l'intero pendio roccioso che raccorda le serre salentine al canale d'otranto era posto sotto il livello del mare; la posizione alla base del pendio delle successioni qui studiate, precedentemente interpretate come depositi costieri ed addebitate a fenomeni di stazionamento del mare dopo una fase di sollevamento della penisola salentina avvenuta in un intervallo di tempo compreso fra il santerniano ed il siciliano, non può essere utilizzata direttamente come indicazione di un paleolivello del mare del siciliano lungo il pendio. d'altra parte ipotizzare una fase di rapido e relativamente intenso sollevamento della penisola salentina nel pleistocene inferiore (durante l'emiliano, prima del sollevamento delle murge), seguita da una stasi e poi da un lentissimo sollevamento tuttora in atto non concorda con quanto riconosciuto nel resto dell'avampaese apulo. infatti, regionalmente, l'inizio del sollevamento dell'avampaese apulo, verosimilmente costante nel tempo, è collocato nel pleistocene medio (ciaranfi et al., 1983; doglioni et al., 1994), o nella parte alta del pleistocene inferiore al passaggio con il pleistocene medio (pieri et al., 1996; tropeano et al., 2002a). inoltre, la presenza di una serie di depositi marini terrazzati e di paleolinee di costa di età pleistocene medio-tirreniano indica un sollevamento tettonico costante in interferenza con oscillazioni eustatiche del livello del mare (ciaranfi et al., 1988). in particolare nell'area salentina vengono segnalati una serie di terrazzi marini deposizionali medio-suprapleistocenici riconosciuti a partire almeno dalla quota di 100 m sul livello del mare (fiore & palmentola, 1987) e spianate di abrasione e vecchie linee di costa dello stesso intervallo di età vengono segnalate anche a partire da quote superiori (d'alessandro et al., 1987; ciaranfi et al.., 1988; ricchetti et al., 1988). è importante sottolineare che sia le più alte spianate di abrasione che i più elevati terrazzi deposizionali giacciono a quote superiori rispetto alle quote di affioramento dei depositi qui studiati. un'ulteriore considerazione neotettonica deriva dall'analisi della distribuzione dei depositi alla base della scarpata. come evidenziato, gli affioramenti sono discontinui e ubicati dove il pendio roccioso presenta brusche rientranze. queste sono poste in corrispondenza di faglie sinsedimentarie la cui attività favoriva la presenza di zone di bypass fra le aree sommitali e la base della scarpata. le faglie tagliano una blanda soglia morfologica posta al margine superiore del pendio che ipotizziamo possa in parte corrispondere ad un originale rilievo morfologico ereditato dalle aree di fronte delle scogliere terziarie riconosciute nell'area da bosellini et al. (1999). l'attività delle faglie avrebbe favorito anche il frequente innesco di frane sottomarine lungo la scarpata. 5. conclusioni le osservazioni sedimentologiche e le considerazioni litostratigrafiche esposte in questo lavoro permettono di attribuire a sistemi deposizionali di scarpata e di base di scarpata i depositi calcarenitici infrapleistocenici affioranti nella parte bassa e alla base del pendio roccioso che ad oriente, verso il canale d'otranto, raccor544 m. tropeano et al. da la regione salentina al mare ionio. questo pendio, già riconosciuto in letteratura come un elemento fisiografico della piattaforma apula fino al messiniano, ha rappresentato localmente il margine della stessa piattaforma anche durante il pleistocene inferiore. le successioni osservate sono riferibili a sistemi carbonatici di tipo foramol che, a differenza di quanto noto in letteratura per depositi coevi affioranti sia nelle murge che nel salento, devono essere considerati non classici sistemi di mare sottile ma piccoli ed isolati sistemi tipo apron di non elevata profondità. le aree di produzione carbonatica vanno ricercate sia nelle serre salentine che lungo il pendio stesso. la nuova interpretazione ambientale di questi depositi porta a rivedere la suddivisione formazionale finora operata in questa porzione della regione salentina, in quanto non vi sarebbe più la necessità di distinguere i depositi delle serre (formazione di uggiano la chiesa) da quelli della base del pendio (calcareniti del salento). entrambi i tipi di deposito andrebbero riferiti alla formazione della calcarenite di gravina, l'unità rappresentativa del parziale annegamento mediopliocenico-infrapleistocenico dell'intero avampaese apulo dovuto alla migrazione del sistema appenninico meridionale verso oriente. infine, alcune faglie dirette e/o trascorrenti che tagliano il pendio e che mostrano attività sinsedimentaria rispetto ai depositi descritti, avrebbero interrotto sia la blanda soglia morfologica presente alla sommità del versante (ereditata dalle scogliere terziarie e che impediva di alimentare ovunque la base del pendio) sia il frequente innesco di frane sottomarine. 6. ringraziamenti si ringraziano l. simone ed e. taddei ruggiero per le profique discussioni e gli utili suggerimenti, n. ciaranfi, s. longhitano e m. schiattarella per la lettura critica del manoscritto. lavoro eseguito e pubblicato con fondi miur (cofin 2002, responsabile nazionale l. simone, responsabile locale a. laviano). lavori citati azzaroli a. 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(1983) le calcareniti calabriane e tirreniane di porto miggiano sul canale d'otranto. geol. appl. idrogeol., xviii, 33-44. 546 m. tropeano et al. ms. ricevuto il 21 maggio 2004 testo definitivo ricevuto il 15 dicembre 2004 ms. received: may 21, 2004 final text received: december 15, 2004 imp.bini_strini& geologia di sottosuolo dell'alta pianura a ne di milano bini alfredo1, strini andrea1, violanti donata2 & zuccoli luisa1 1dipartimento di scienze della terra, università degli studi di milano, via mangiagalli, 34, 20133 milano; alfredo.bini@unimi.it 2dipartimento di scienze della terra, università di torino, via valperga caluso 35, 10125 torino; violanti@dst.unito.it riassunto: bini a., strini a, violanti d. & zuccoli l., geologia di sottosuolo dell'alta pianura a ne di milano. (it issn 0394-3356, 2004). la ricostruzione del modello geologico del settore di alta pianura a ne di milano è stata possibile integrando i dati derivanti dal rilevamento geologico di superficie e quelli provenienti dall'analisi dei dati di sottosuolo. il rilevamento di superficie ha permesso di distinguere sia unità allostratigrafiche sia unità litostratigrafiche costituite principalmente da depositi fluviali, glaciali e fluvioglaciali di età compresa tra il pleistocene inferiore e il momento attuale. la geologia di sottosuolo è stata ricostruita mediante l'analisi dei cuttings provenienti da pozzi per acqua, di cui sono state eseguite descrizioni sedimentologiche, petrografiche e paleontologiche. questi dati sono stati integrati con stratigrafie di ulteriori pozzi esistenti di cui non è stato possibile analizzare direttamente i cuttings di perforazione. la correlazione è stata fatta mediante la redazione di sezioni rettilinee variamente orientate in modo da avere una ricostruzione tridimensionale del sottosuolo. le sezioni sono state tracciate in modo da intersecare il maggior numero di pozzi e su di esse sono stati anche proiettati i pozzi distanti non più di 300 m dalle sezioni stesse. la ricostruzione si è basata sul riconoscimento e la ricostruzione di superfici e corpi sepolti individuabili tramite descrizioni litologiche o livelli marker, la cui validità è stata verificata mediante la taratura effettuata con i cuttings e i dati del rilevamento di superficie per la porzione sommitale della successione. questa analisi ha consentito di riconoscere anche alcune unità solo sepolte (allogruppo di vimercate, allogruppo di ronco briantino, ceppo di lomagna). la ricostruzione della geologia di sottosuolo ha quindi consentito di avere una visione d'insieme dell'evoluzione della zona permettendo anche il perfezionamento dell'interpretazione della geologia di superficie in zone dove la scarsità di affioramenti rendevano dubbia l'interpretazione dei dati di rilevamento. e' stato infine redatto un modello di evoluzione paelogeografica della zona. abstract: bini a., strini a., violanti d. & zuccoli l., subsurface geology of the ne of milan high plain. (it issn 0394-3356, 2004). the geological setting of an high plain area ne of milan is carried out by the correlation among superficial data and underground ones. allo-units and litho-units have been recognised in the field relief. the units are principally composed of fluvial, glacial and glaciofluvial sediments and they have an age comprised between the lower pleistocene and the present time. in order to carry out the underground model, cuttings of water wells have been analised. the main characteristics used in cutting descripitons are: sedimentology, petrography and fossils contents. moreover, a great number of drilling logs have been considered. the correlation is carried out using rectilinear sections; these sections are oriented in various directions, so that it is possible to determine a three dimensional model of the underground structures. drills distant no more than 300 m from the sections have been projected on them. the geological reconstruction is based on the determination and the reconstruction of buried surfaces and geological bodies. these surfaces and bodies are recognised by marker or lithological descriptions that are calibrated by superficial data and cutting analysis. in this work three buried units have been recognised. they are: allogruppo di vimercate, allogruppo di ronco briantino and ceppo di lomagna. the underground model is useful to understand the geological evolution of the area. it is also useful to understand the superficial geological setting in areas in which outcrops are too distant to make a certain model. finally, a paleogeographic evolution model of the area is proposed. parole chiave: alta pianura, depositi plio pleistocenici, geologia di sottosuolo, milano, italia. keywords: high plain, plio-pleistocenic deposits, subsurface geology, milan, italy. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 343-354 1. introduzione la comprensione dell'evoluzione plioquaternaria della pianura non può prescindere da una analisi della geologia di sottosuolo. infatti, come messo in evidenza da precedenti lavori (bini, 1997a; zuccoli, 1997, 2000), la ricostruzione di sottosuolo permette di individuare reticoli idrografici sepolti totalmente obliterati da eventi successivi e che testimoniano situazioni paleogeografiche completamente diverse da quelle attuali. inoltre l'analisi di sottosuolo consente di raffinare il modello derivante dal rilevamento geologico di superficie. per poter realizzare uno studio di questo tipo è però necessaria una stretta correlazione tra i dati di superficie e quelli di sottosuolo che, almeno in alcuni punti chiave, devono essere tarati tramite lo studio diretto di cuttings di perforazione o carote. in questo lavoro si presentano i risultati di uno studio di questo tipo effettuato nell'area di alta pianura a nordest di milano. 344 a. bini et al. 2. inquadramento geografico l'area studiata è collocata nell'alta pianura milanese, a ne di milano (fig. 1a), al margine delle avanzate dei ghiacciai mediopleistocenici, in particolare nella zona a cavallo tra il lobo dell'adda (a est) e il lobo del lambro (a ovest) dell'anfiteatro del lario, e comprende quindi le morene più esterne di questi lobi. l'area è caratterizzata a est dalla profonda incisione del fiume adda che taglia la successione sedimentaria per quasi 80 m in corrispondenza del ponte di paderno. internamente alla gola numerosi terrazzi testimoniano diverse fasi di riempimento e svuotamento della valle. verso ovest mancano incisioni altrettanto marcate e la zona è caratterizzata da terrazzi meno pronunciati, in genere non superiori alla decina di metri, che si chiudono verso sud isolando i lembi più alti e più vecchi della successione. 3. materiali e metodi lo studio è stato eseguito confrontando e correlando i dati provenienti dal rilevamento della geologia del quaternario di superficie e dai dati di sottosuolo, provenienti da stratigrafie di pozzi e sondaggi o dallo studio diretto di cuttings di perforazione e da spezzoni di carote. nel rilevamento di superficie sono state distinte sia unità litostratigrafiche sia allostratigrafiche secondo un criterio di rilevamento da tempo consolidato (bini, 1997b). le stratigrafie dei pozzi sono state fornite da studi privati, enti pubblici e imprese. nove pozzi ubicati nei comuni di agrate brianza, burago di molgora, ronco briantino e cornate d'adda sono stati studiati in dettaglio in alcune tesi laurea (lorito, 1997; maroni, 1994; vedrietti, 1993). i cuttings e gli spezzoni di carota sono stati analizzati dal punto di vista sedimentologico, distinguendo i livelli in base alla granulometria; sono state riconosciute le petrografie dei ciottoli delle ghiaie e dei conglomerati ed è stata prestata particolare attenzione all'eventuale contenuto paleontologico. le determinazioni dei microfossili sono state eseguite da donata violanti (università di torino), quelle relative al nannoplancton da davide castradori (agip) e quelle dei macrofossili da cesare corselli (università di milano bicocca). e' stato descritto il grado di alterazione dei ciottoli ed è stato determinato il colore della frazione fine mediante le tavole munsell. poichè i pozzi sono stati perforati per lo più a distruzione, sono andate perdute tutte le informazioni riguardo alle strutture sedimentarie quali laminazioni, gradazione o alternanze di livelli molto sottili. le sezioni sono state tracciate a scala verticale esagerata (1:1.000 in verticale, 1:25.000 in orizzontale) partendo dalla base topografica ctr (ed. 1984). sulle sezioni sono stati inseriti i dati rilevati (geologia superficiale e morfologia). le sezioni sono rettilinee, a differenza della maggior parte delle sezioni finora usate nelle ricostruzioni geologiche di questa zona, e passanti per i pozzi di maggiore interesse. i pozzi distanti non più di 300 metri dalla traccia della sezione, in zone coerenti dal punto di vista geologico, sono stati proiettati sulla sezione stessa. sono state tracciate principalmente sezioni perpendicolari e longitudinali al bacino di sedimentazione; inoltre sono state tracciate alcune sezioni oblique per poter seguire nelle tre dimensioni i corpi e le superfici riconosciuti nelle sezioni. la densità delle sezioni non è omogenea in quanto dipende strettamente dalla distribuzione dei pozzi, concentrati nelle aree di maggiore presenza industriale e abitativa (fig. 1b). le correlazioni tra i pozzi sono state eseguite partendo dai dati direttamente osservati, cioè dai dati di terreno e dai dati provenienti dall'analisi dei cuttings di perforazione, estesi poi alle stratigrafie dei pozzi adiacenti. l'analisi diretta dei cuttings di perforazione ha permesso non solo di distinguere i livelli in base alle caratteristiche tessiturali e petrografiche ma anche di evidenziare paleosuoli e profili di alterazione consentendo una migliore definizione di unità simili per sedimentologia e petrografia. nell'analisi delle stratigrafie esistenti sono stati reintepretati alcuni termini usati dai sondatori; per esempio, i livelli definiti come torba solo raramente sono effettivamente costituiti da torba, ma più generalmente sono livelli ricchi in materia organica. i livelli definiti come argilla e ciottoli, argilla rossa e argilla gialla corrispondono per lo più a unità molto alterate. sulla base di queste osservazioni è stato possibile, considerando le unità affioranti nelle adiacenze dei pozzi, tracciare in sottosuolo i limiti riconosciuti in superficie e, nel contempo, individuare anche alcune unità solo sepolte. il reticolo di sezioni ha permesso inoltre di seguire nelle tre dimensioni le geometrie dei corpi sepolti, attribuendo quindi un preciso significato geologico alle superfici riconosciute. la ricostruzione della geologia di sottosuolo, dal punto di vista evolutivo e paleogeografico, ha consentito inoltre di affinare il modello di superficie in quelle aree in cui era meno chiaro. fig. 1 a posizione dell'area di studio (in nero); b carta schematica della zona; in grigio è indicata l'estensione dei centri abitati e l'idrografia principale: le linee corrispondono alla traccia delle sezioni, i cerchi indicano i pozzi analizzati direttamente. a study area location (in black); b schematic map of the study area. grey colour shows residential areas and the main hydrography; straight lines are the geological sections, circles are the directly analysed wells. 4. geologia di superficie l'area era già stata oggetto in passato di numerosi studi (desio, 1938; riva, 1941, 1943, 1947, 1953, 1957; venzo, 1948a, 1948b, 1949, 1950) che hanno analizzato in generale l'"anfiteatro di villa d'adda". lavori più specifici su singoli aspetti sono stati rivolti alla successione affiorante nella forra dell'adda (orombelli e gnaccolini, 1978; orombelli 1979; caldara et al., 1988; g i u s s a n i , 1992) oppure ai paelosuoli (ugolini e orombelli, 1968; cremaschi, 1987). bini (1994) pubblica una carta del settore orientale dell'anfiteatro dell'adda, bini e rigamonti (2000) e rossi e rigamonti (2000) analizzano la successione affiorante lungo la sponda bergamasca dell'adda. il nuovo rilevamento di superficie (strini, 2001) è riportato schematicamente in fig. 2. nella carta, a causa della scala ridotta, sono state tralasciate le unità affioranti nella forra dell'adda e il ceppo della molgora. di seguito è fornita una descrizione sintetica delle unità affioranti, mentre nelle tabelle 1, 2 e 3 sono confrontate le principali caratteristiche delle diverse unità. il termine inferiore della successione è rappresentato dalle argille di conche che affiorano sporadicamente solo nella forra dell'adda in periodi di magra. in questa unità sono raggruppati affioramenti di sabbie e limi che appartengono molto probabilmente ad ambienti diversi. sono presenti sia macrofossili di origine marina (orombelli, com. pers.), sia livelli ricchi in sostanza organica, sia livelli fortemente screziati o arrossati. venzo (1950) rinviene in un affioramento presso paderno d'adda un dente di anancus arverniensis. poichè la successione è profondamente deformata da frane a grande scala che interessano le pareti della forra (caldara et al. 1988; giussani, 1992) e poichè gli affioramenti sono sempre di ridotte dimensioni e distanti tra loro non è possibile, di fatto, ricostruire con precisione la successione sedimentaria solo in base ai dati di superficie. superiormente alle argille di conche affiora una potente successione di conglomerati suddivisi in tre formazioni: ceppo del naviglio di paderno, ceppo del brembo e ceppo dell'adda. la divisione è resa possibile dalla marcata differenza della composizione petrografica tra le diverse unità. il ceppo del naviglio di paderno affiora nella parte settentrionale della valle dell’adda e costituisce il termine inferiore della successione; è costituito principalmente da carbonati e da arenarie calcaree provenienti dalle successioni affioranti a nord dell'area studiata. e' caratteristica la presenza di grossi blocchi di arenaria di forma subangolare (sino a 50 cm). in un affioramento, a tetto del ceppo del naviglio di paderno è presente un potente paleosuolo (spessore 250 cm) che marca il limite con il soprastante ceppo dell’adda. il ceppo del brembo si caratterizza per l'abbondante presenza di ciottoli di litologie brembane (collio, verrucano lombardo). esso costituisce il termine inferiore della successione a sud di porto d’adda ed è in parte eteropico con il ceppo del naviglio di paderno. questi conglomerati sono suturati dal ceppo dell’adda, con petrografia più variabile, che affiora lungo tutta la forra. la parte superiore del ceppo dell'adda è profon345geologia di sottosuolo ... damente alterata e costituisce una unità a sè stante denominata formazione di trezzo sull'adda. questa formazione si caratterizza per l'estrema alterazione che interessa l'intero spessore dell'unità con oltre il 90% dei ciottoli totalmente alterato. il limite inferiore è un limite graduale con formazione di organi geologici che la mette in contatto con il sottostante ceppo dell'adda. la formazione di trezzo sull’adda e il ceppo dell'adda affiorano non solo lungo l'adda, ma anche lungo alcuni corsi d'acqua minori quali il rio vallone e il rio della cavetta. il ceppo della molgora è costituito anch'esso da un conglomerato a cemento carbonatico e contenuto petrografico variabile e, sebbene sia diffusamente presente in sottosuolo, ha scarsa evidenza e continuità in affioramento. esso è presente nel settore più occidentale, lungo la molgora, il curone e corsi d'acqua minori. superiormente alla formazione di trezzo sull’adda è presente la successione dei depositi glaciali e fluvioglaciali corrispondenti alle glaciazioni medio e tardopleistoceniche. i rapporti tra le unità sono alquanto articolati a causa della complessa geometria dei due lobi dell’anfiteatro in cui si sono alternate fasi di costruzione e smantellamento. sono stati riconosciuti i depositi appartenenti a cinque unità allostratigrafiche che, dalla più antica alla più recente, sono: allogruppo del bozzente, alloformazione della specola, alloformazione di binago, allogruppo di besnate e alloformazione di cantù. queste unità corrispondono a cinque diverse glaciazioni. la loro identificazione è stata fatta in base alle fig 2 carta geologica schematica dell'area a ne di milano. schematic geological map of the area ne of milan. 346 tab. 1 sintesi delle principali caratteristiche delle principali unità affioranti (ad esclusione dei conglomerati e delle coperture loessiche). main charactherisics of the outcropping units (except conglomerates and loess). allogruppo del bozzente allogr. alloformaz. alloformaz. allogr. alloformaz. formaz. alloformaz. del ponte della di di di di c.na di c.na di specola binago besnate cantù ronchi fontana paderno . pella facies till, fluviogl. till, fluviogl. fluviogl. till, fluviogl till, fluviolg. fluviog., fluvioglaciali, fluviali versante fluviali litologia diamicton, diamicton, ghiaie ghiaie e diamicton, diamicton, ghiaie ghiaie, ghiaie, limi ghiaie sabbie ghiaie sabbie e sabbie con con interc. occasionali sabbiose intercalz. sabbiose spessore del > 10 m > 10 m non det. fino a 68 m >250 cm 4 m 1,5 m profilo alteraz. clasti alterati alterati non alterati alerati alterati** decarbonatati decabornatati carb. in superficie clasti alterati alterati occasionali arenizzati o con con cortex ridotto, con cortex o non alterati alpini arenizzati cortex rari arenizzati non alterati % clasti alterati > 90% 90%* < 10% > 70% > 90** 40% < 10% colore da 5yr da 2.5yr (occ) 10yr 7.5 yr da 7.5yr a 10yr da 7.5 yr 10yr matrice a 10yr a 10yr occas 5yr, a 10 yr 10yr argilla abbondante abbondante assente abbondante presente scarsa assente secondaria copertura -m. carmelo, 5yr, assente 10yr, 7.5yr, 10yr 10yr o assente loessica 7.5yr, 7.5yr screziato, assente 7.5yr screziato, occasionale 5yr 10yr morfologia non dà luogo ampia cerchia terrazzi interni morene morene e piane piane ampie piane fluviogl. a morfologie nella zona di alla forra conservate fluviogl. peculiari camparada dell'adda e piane fluviogl. poco conservate e piane fluvioglaciali smantellate + il profilo di alterazione è difficilmente ossorvabile a causa dell'esposizione lungo pareti abrupte. centazione da assente a buona in alcui livelli; * stima fatta sulla parte inferiore della successione a causa delle difficili condizioni di affiormento; ** affioramenti con flysch dominanti che sono tutti decarbonatati. tab 2 caratteristiche principali delle coperture loessiche. main charactheristics of loess units. monte 5yr 7.5yr 10yr 7.5 yr 10yr carmelo screziato screziato colore da 5ry a 7.5yr 5yr 7.5 yr 10yr 7.5 yr con 10yr (2.5yr occ.) screziature con glosse più arrossate e più giallatre consolidamento molto sovraconsolidato occasionalmente occasionalmente sovraconsolidato da sovraconsolidato sovraconsolidato sovraconsolidato sovraconsolidato a non sovraconsolidato contenuto abbondante abbondante presente scarsa o assente abbondante presente in argilla figure sempre presenti occasionali occasionali occasionali sempre presenti sempre presenti pedogenetiche da gelo unità a tetto alloformazione loess 7.5yr loess 10yr alloformaz. 7.5 yr,10yr 10yr più antica della specola di binago screziato unità a letto più alloformazione alloformazione alloformazione allogruppo alloformazione 7.5yr screziato giovane di c.na fontana della specola della specola di besnate della specola e m. carmelo a. bini et al. 347 caratteristiche di alterazione e alla posizione geometrica. non esistono, sul territorio analizzato, elementi per poter effettuare datazioni geocronometriche. tuttavia, correlando le unità a quelle dell’anfiteatro del lario (settore occidentale) si possono attribuire al pleistocene medio l'allogruppo del bozzente, l'alloformazione della specola e l'alloformazione di binago (bini, 1987, 1997a; zuccoli, 1997, 2000); al pleistocene mediosuperiore l'allogruppo di besnate mentre l'alloformazione di cantù corrisponde all'ultima glaciazione ed è quindi riferibile al pleistocene superiore (bini, 1997a). l’allogrupo del bozzente si caratterizza per una estrema alterazione dei clasti, un forte arrossamento e un arricchimento in argilla secondaria. l’alloformazione della specola è caratterizzata da una alterazione meno intensa, ma sempre cospicua, interessando oltre il 70% dei clasti e raggiungendo, nella zona di definizione, 8 m di spessore (zuccoli, 1997). l’alloformazione di binago e l’allogruppo di besnate hanno un'alterazione marcatamente più ridotta. l’alloformazione di cantù ha una alterazione estremamente ridotta con fronte di decarbonatazione che si attesta a una profondità di 1,5 m e l’alterazione che interessa circa il 10% dei ciottoli. tutte le unità, ad eccezione dell'alloformazione di cantù, sono coperte da una o più coltri di loess. l'allogruppo del bozzente è coperto a tetto da una caratteristica coltre di loess fortemente pedogenizzata che è stata elevata al rango di formazione denominata formazione di monte carmelo (bini, 1997a; zuccoli, 1997, 2000). nell'area sono state distinte in totale 6 coltri loessiche i cui rapporti stratigrafici non sono sempre semplici da definire. infatti l'intensa opera di sfruttamento come materia prima per l'edilizia, e la rimobilizzazione durante le fasi glaciali successive, rende gli affioramenti di loess piuttosto frammentari. 5. geologia di sottosuolo l'area è già stata oggetto di una prima ricostruzione di sottosuolo rivolta soprattutto alla caratterizzazione degli acquiferi (denti et al. 1988) mentre alcuni lavori precedenti (desio e villa, 1960; mariani, 1938) avevano considerato singole stratigrafie di pozzi. nella ricostruzione presentata in questo lavoro sono state individuate le unità già riconosciute in superficie e alcune unità solo sepolte che sono l'allogruppo di ronco briantino, l'allogruppo di vimercate e il ceppo di lomagna. i caratteri e il significato paleogeografico di queste unità sono descritte nel paragrafo successivo. la ricostruzione di sottosuolo ha permesso di individuare un reticolo di paleovalli, in parte con andamento completamente diverso dall'attuale idrografia, che è illustrato nella fig. 3. nella stessa figura è indicata la principale idrografia attuale. nella figura 4 (a,b,c) sono illustrati i rapporti stratigrafici tra le unità riconosciute in sottosuolo. tab 3 sintesi delle unità conglomeratiche affioranti. main characteristics of the conglomerates units outcropping in the area. ceppo del naviglio di paderno ceppo del brembo ceppo dell'adda ceppo della molgora carbonati 41,8% 40,8% 59,3% 49% flysch + congl. di sirone 54% 16,3% 15,4% 38,3% selce 2% 1,6% 0,7% 0,4% cristallini + metamorfici 1,4% 16,6% 18,7% 9,1% quarzo 0,2% 4,9% 2,1% 2% verrucano 0,2% 15,5% 1,5% 0,2% vulcaniti 0,4% 3,6% 2% 1,3% ultramafiti 1,7% altro 0,4% superficie erosionale, erosionale, organi geolgoci organi geologici superiore con paleosuolo cementazione buona da buona a media da buona a media da buona a scarsa fig 3 carta delle paleovalli riconosciute in sottosuolo. in grigio è indicata l'idrografia attuale. map of the paleovalleys determined by underground analisis. present hydrograpy in grey. geologia di sottosuolo ... 348 fig 4 schemi dei rapporti stratigrafici a schema dei rapporti stratigrafici orientato e-w a nord del territorio esaminato. si noti che la pelovalle 1 è indicata due volte per specificarne i rapporti con le altre unità. la paleovalle 1 è l'unica disposta e-w, mentre tutte le altre sono n-s; b schema dei rapporti stratigrafici orientato e-w a sud del territorio esaminato all'altezza di agrate brianza cavenago di brianza. si noti che l'assetto geologico è più semplice di quello a nord; c schema dei rapporti stratigrafici in un transetto n-s della zona esaminata (asse ronco briantino vimercate burago di molgora agrate brianza). si noti la differenza di età del tetto delle unità marine spostandosi da nord verso sud. bri = allogruppo di ronco briantino; cn = ceppo del naviglio di paderno; cr = ceppo del brembo; cd = ceppo dell'adda; tre = formazione di trezzo sull'adda; cm = ceppo della molgora; cl = ceppo di lomagna; bo = allogruppo del bozzente; spe = alloformazione della specola; be =allogruppo di besnate indifferenziato. stratigraphic frameworks of the area. a stratigraphic framework e-w in the northern part of the study area: note that paleovalley 1 is signed twice in order to specify the stratigraphic relationships. the paleovalle 1 is e-w oriented; all the other ones are n-s oriented. b stratigraphic framework e-w in the south part of the area at agrate brianza cavenago di brianza latitude. the geological settlement is more simple in this area than in the north one; c stratigraphic framework n-s oriented (ronco briantino vimercate burago di molgora agrate brianza axis); it is evident the different age of the top of the marine units moving from the northern part to the southern part. bri = allogruppo di ronco briantino; cn = ceppo del naviglio di paderno; cr = ceppo del brembo; cd = ceppo dell'adda; tre = formazione di trezzo sull'adda; cm = ceppo della molgora; cl = ceppo di lomagna; bo = allogruppo del bozzente; spe = alloformazione della specola; be =allogruppo di besnate indifferenziato. a. bini et al. in linea di massima si può dire che l'allogruppo di ronco briantino costituisce un insieme di unità continentali che riempiono la paleovalle 1. l'allogruppo di vimercate costituisce il riempimento di della paleovalle 3 e di parte della 4 ed è possibile distinguere al suo interno due unità, una più grossolana e una più sabbiosa. nella parte superiore di questa unità confluiscono sicuramente anche i deposti appartenenti alle facies fluvioglaciali delle unità più vecchie che non possono essere distinti in singole unità. infatti i depositi fluvioglaciali appartenenti a glaciazioni differenti possono essere distinti solo in base all'alterazione, ma in una successione sedimentaria ricostruita solo in base alle stratigrafie di pozzi o cuttings esi appariranno per lo più come un'unica sequenza di ghiaie in cui gli eventuali orizzonti di alterazione possono essere stati erosi e quindi riconosciuti solo occasionalmente. il ceppo di lomagna, che costituisce il riempimento della paleovalle 4, non è costituito da un unico evento sedimentario in quanto contiene paleosuoli, più abbondanti verso l'alto della successione. 6. ricostruzione paleogeografica la ricostruzione della geologia di sottosuolo ha permesso una prima ricostruzione dell'evoluzione paleogeografica dell'area, a partire dal pliocene superiore. osservando gli schemi dei rapporti stratigrafici si nota come la situazione sia molto articolata a nord e tenda a semplificarsi verso sud. dopo la fase di erosione messiniana, l'area era invasa da bracci di mare che penetravano profondamente nella valle del lario. a differenza dell'area a sud del lago maggiore, dove sono stati chiaramente individuati i sedimenti che testimoniano la progradazione del ticino verso la pianura durante il pliocene medio (bini, 1997a; zuccoli, 1997), nell'area interessata la sedimentazione marina continua per tutto il pliocene. l'adda percorreva la valle del ramo di como del lario al termine della quale deponeva il ceppo di portichetto del pliocene superiore (tomasi, 2001). nell'attuale valle dell'adda, oggetto del presente studio, le condizioni marine sono perdurate sino al pliocene superiore. più complessa è la situazione della valle del ramo di lecco del lario che doveva essere in qualche modo ostruito e la cui trattazione esula dagli scopi del presente lavoro. la successione sedimentaria marina appare spesso intervallata da depositi grossolani che possono essere giustificati considerando la limitata distanza dalla costa. la sedimentazione al fondo poteva quindi ricevere apporti dai versanti, da frane, da correnti di torbida o, semplicemente, dalla progradazione di torrenti che costruivano il proprio delta conoide. da condizioni marine si passa gradualmente a condizioni di laguna, in cui si depositano livelli particolarmente arricchiti in materia organica. tuttavia la mancanza di una fitta rete di pozzi e sondaggi non consente, al momento attuale, una ricostruzione più particolareggiata dell'andamento della linea di costa e dell'evoluzione del bacino. nel pliocene superiore, condizioni marcatamente continentali sono testimoniate dall'incisione nei sedimenti marini di una valle disposta e-w riempita da sedimenti fluvioglaciali, fluviali e glaciali (paleovalle 1; fig. 3). la direzione di approfondimento della valle è verso est, cioé verso l'attuale corso dell'adda. il riempimento potrebbe testimoniare una prima glaciazione correlabile in via preliminare con la glaciazione s. salvatore (bini, 1997a; zuccoli, 1997, 2000). con il pleistocene inferiore il quadro paleogeografico cambia radicalmente e la sedimentazione nell'aerea è dominata da due flussi principali, uno proveniente da nord e uno da est (fig. 5). i corsi d'acqua provenienti da nord incidono nelle unità marine una valle ben seguibile in sottosuolo che viene riempita dal ceppo del naviglio di paderno (paleovalle 2). l'andamento della valle è circa nnessw nel settore più settentrionale, piega più marcatamente verso sw tra bellusco e ornago fino all'altezza di cavenago di brianza dove la valle devia ad angolo retto verso sud. contemporaneamente, da est, un corso d'acqua proveniente dal bacino del brembo depositava una potente successione di ghiaie, ben riconoscibili in base alla petrografia. le due piane in una prima fase rimangono separate da un dosso disposto circa n-s costituito da depositi marini (argille di conche) ben individuabile in sottosuolo da colnago a roncello (fig.6). con il progredire della sedimentazione il brembo da est e i corsi d'acqua da nord colmano la paleovalle e superano l'alto in depositi marini cosicchè le due piane diventano coalescenti; l'eteropia tra le due formazioni è ipoteticamente collocabile in sottosuolo tra porto 349 fig 5 mappa schematica dell'area durante il pleistocene inferiore. le piane del ceppo del naviglio di paderno e del ceppo del brembo sono separate da un alto in unità marine. l'eteropia tra le due unità è dedotta dai dati di sottosuolo. le frecce indicano la direzione degli apporti del ceppo del naviglio di paderno (cn) e del ceppo del brembo (cr). schematic map showing the study area during the early pleistocene, deduced by ceppo del naviglio di paderno and ceppo del brembo outcrops and by underground analysis. the ceppo del naviglio di paderno plain and ceppo del brembo plain are divided by a knoll (signed with cross) composed of marine units. heteropic relationship is evident in underground analysis. arrows show the main flow direction of ceppo del naviglio di paderno (cn) and ceppo del brembo (cr). geologia di sottosuolo ... 350 fig. 6 sezione geologica all'altezza di colnago. e' evidente l'alto in unità marine che divide il ceppo del brembo (cr) dal ceppo del naviglio di paderno (cn). con il proseguire della sedimentazione le due unità superano il dosso e le due unità diventano eteropiche. cd = ceppo dell'adda, tre = formazione di trezzo sull'adda; ca = alloformazione di cantù; bps = unità di porto d'adda superiore (allogruppo di besnate); t = torba o materia organica; m = depositi marini; a = resti vegetali; b = conchiglie. geological cross section near colnago. the knoll made up of marine units divides ceppo del brembo (cr) and ceppo del naviglio di paderno (cn). when the two units reach the top of the knoll, the two units become heteropic. cd= ceppo dell'adda; tre = formazione di trezzo sull'adda; ca = alloformazione di cantù; bps = unità di porto d'adda superiore (allogruppo di besnate); t = peat or organic matter; m = marine deposits; a = vegetals remains; b = shells a. bini et al. d'adda e colnago. verso ovest la piana costituita dal ceppo del naviglio di paderno si estendeva fino a ronco briantino e villanova dove in sottosuolo è evidente la progressiva riduzione dei depositi di questa formazione. la forte eterogeneità dei depositi appartenenti al ceppo del naviglio di paderno in sottosuolo fa supporre che in realtà l'intero corpo non sia la testimonianza di un unico evento deposizionale ma risulti dalla deposizione di più corpi sedimentari deposti in condizioni diverse. la durata di questa fase non è identificabile a causa della mancanza di elementi databili nella successione, tuttavia è stata sufficiente affinché si potesse creare, almeno localmente, un paleosuolo a tetto del ceppo del naviglio di paderno. su una paleosuperfice probabilmente molto articolata, costituita dalle due piane coalescenti, si depone un nuovo corpo di ghiaie che oblitera completamente la topografia precedente e che si espande per una superficie considerevole, dall'adda fino ronco briantino e carnate a ovest e da paderno d'adda fino all'autostrada mi-ve per spingersi ancora più sud dell'area rilevata. questi depositi, costituenti il ceppo dell'adda, testimoniano un corso d'acqua di notevoli dimensioni proveniente da nord (fig. 7). questo conglomerato era stato attribuito precedentemente al dominio valsassinese (orombelli, 1979), tuttavia il rilevamento geologico di tutto l'anfiteatro del lario, lo spessore, l'estensione e la petrografia del conglomerato indicano che il ceppo dell'adda costituisce l'espressione sedimentaria dell'adda. la diversione dell'adda da como a lecco avviene durante il pleistocene inferiore. allo stato attuale delle ricerche non è possibile stabilire se la diversione sia dovuta a tettonica, a semplice dinamica fluviale o ad una glaciazione. la successione costituita dal ceppo dell'adda e dalle sottostanti unità è successivamente tagliata da una valle (paleovalle 3) che disarticola la superficie originaria (figg. 3 e 8). la paleovalle 3 inizia dal versante dell’attuale valle dell’adda (giussani, 1992), ha un andamento circa ne-sw nel tratto più a monte e piega in modo deciso verso sud in corrispondenza dell'abitato di vimercate. questo andamento ricalca in parte quello della paleovalle 2. una seconda paleovalle (4) si imposta più a ovest della precedente. la valle, tagliata direttamente nei depostiti marini, ha un andamento n-s nel tratto più settentrionale, dove ricalca l'attuale corso della molgora, mentre in corrispondenza di vimercate cambia di direzione verso sw per poi disporsi parallelamente alla paleovalle 3. i talweg delle due paleovalli restano separati sino alla loro confluenza all’altezza di caponago. le valli 3 e 4 testimoniano un fenomeno erosivo di portata considerevole, se si considera che all'altezza dell'abitato di bernareggio la differenza di quota tra il talweg e il top dei versanti della paleovalle 3 è di quasi 100 m. la forma della paleovalle 3 mostra, in destra idrografica, un ampio semicerchio (fig. 3). in corrispondenza di questo e a ovest del talweg, il fondovalle costituisce un ripiano sul quale insistono corpi di conglomerati via via più spessi andando in direzione del piastrone di ceppo dell'adda (fig. 8). questi depositi possono essere interpretati come corpi di frana, in analogia con quanto attualmente visibile nella forra dell'adda (caldara et al., 1988) dove la successione è dislocata da imponenti fenomeni di rilascio. i riempimenti delle paleovalli 3 e 4 presentano molte analogie. in una prima fase la paleovalle 3 è percorsa da corsi d'acqua a energia elevata, che depongono sedimenti grossolani costituenti la porzione inferiore dell'allogruppo di vimercate. l'energia di questi corsi d'acqua diminuisce verso sud come è testimoniato dal ridotto spessore di questi depositi. successivamente e contemporaneamente al progressivo colmamento della valle l'energia dei corsi d'acqua si riduce a tal punto che si instaurano sempre più spesso specchi d'acqua stagnante, con deposizione di livelli fini ricchi in materia organica. con il progredire della sedimentazione viene superato l'alto topografico che separava le valli 3 e 4 cosicchè i corsi d'acqua della palevoalle 3 possono divagare anche nella paleovalle 4, che era stata riempita dai depositi grossolani del ceppo di lomagna, e che, in questa fase, non è più attiva e non presenta più apporti da nord. successivamente le valli vengono nuovamente percorse da corsi d'acqua a elevata energia che trasportano i sedimenti grossolani, oggi costituenti il ceppo della molgora, parzialmente affiorante presso aicurzio, vimercate, cernusco lombardone e in altre località. in questo conglomerato sono presenti sia corpi con clasti di litologie locali, sia corpi con clasti di litologie cristalline. il corso d'acqua che scorreva nella paleovalle 4 depositava ghiaie di composizione strettamente locale provenienti, almeno in parte, dal bacino del curone. gli apporti con marcato incremento di litologie esotiche, dato che il ceppo della molgora è successivo ai primi eventi glaciali, possono essere attribuiti al rima351 fig. 7 carta schematica della piana del paleo adda, dedotta dagli affioramente del ceppo dell'adda, della formazione di trezzo sull'adda e dai dati di sottosuolo. cd = ceppo dell'adda. le frecce indicano la direzione principale degli apporti. schematic map of the paleo adda plain, deduced from ceppo dell'adda and formazione di trezzo outcrops and underground analyses. cd = ceppo dell'adda. arrows show the main flow direction. geologia di sottosuolo ... neggiamento di precedenti sedimenti glaciali o fluvioglaciali. con il pleistocene medio le condizioni cambiano in modo radicale in quanto il territorio è interessato dalle avanzate glaciali di cui rimangono ampie tracce in superficie. le prime grandi avanzate glaciali depositano i sedimenti oggi compresi nell'allogruppo del bozzente in cui si individuano almeno due fasi maggiori (bini, 1997a; zuccoli 1997, 2000). la prima fase di avanzata glaciale (formazione di c.na ronchi pella) arrivava a lambire l'abitato di usmate -velate; uno scaricatore glaciale doveva percorrere la paleovalle 5 disposta circa n-s e ben evidente da lomagna a carnate. le morene relative a questa fase sono state in seguito smantellate e oggi la formazione di c.na ronchi pella è individuabile solo in sporadici affioramenti. il successivo evento glaciale (glaciazione c.na fontana, i cui depositi sono raggruppati insieme alla f. di c.na ronchi pella nell'allogruppo del bozzente) raggiungeva in pratica il limite della glaciazione precedente, costruendo l'imponente cerchia di camparada a ovest e una cerchia, oggi smantellata, a est. di quest'ultima rimane evidente il dosso di bernareggio mentre verso est la cerchia si chiudeva probabilmente poco a nord di cornate d'adda. antistante alla cerchia di camparada si estendeva un'ampia piana fluvioglaciale, oggi smembrata e testimoniata da terrazzi che si chiudono all'altezza di arcore. più a est, nel lobo dell'adda si instaurava una piana fluvioglaciale testimoniata da superfici terrazzate a sud degli abitati di bernareggio e carnate; le acque fluvioglaciali sfruttavano in parte la paleovalle 3 ormai 352 fig. 8 sezione geologica tra usmate e castel negrino; sono evidenti le palevalli 3 e 4. il profilo della paleovalle 3 mostra un'ampia spianata sulla quale si impostano corpi di conglomerato intepretati come il prodotto di frane alla grande scala lungo i versanti della paleovalle. le sigle delle unità sono le medesime della fig. 5. bor = formazione di c.na ronchi pella; bof = alloformazione di c.na fontana bce = unità di cernusco lombardone; bos = unità di osnago; t = torba o materia organica; a = resti vegetali; b = conchiglie. cross section from usmate to castel negrino; paleovalleys 3 and 4 are evident. note that the paleovalle 3 profile has a wide terrace on which conglomerates bodies are present. the conglomerates are intrepreted as the effect of great landslide along the paleovalley slope. the unit abbreviations are the same of fig. 5. bor = formazione di c.na ronchi pella; bof = alloformazione di c.na fontana bce = unità di cernusco lombardone; bos = unità di osnago; t = peat or organic matter; a = vegetals remains; b = shells. a. bini et al. quasi totalmente riempita mentre ancora più a est, lungo l'allineamento castel negrino cornate d'adda, la precedente superficie topografica costituita dalla formazione di trezzo sull'adda rimaneva preservata dall'erosione, in prossimità di castel negrino, da un terrazzo vergente a nord. uno scaricatore glaciale minore doveva sfruttare l'incisione del rio vallone. le glaciazioni successive hanno costruito morene interne alle precedenti, ancora conservate nel lobo del lambro e totalmente smantellate (per quanto riguarda l'alloformazione della specola e l'alloformazione di binago) nel lobo dell'adda. durante la glaciazione specola un'ampia valle fluvioglaciale disposta nne-ssw si impostava tra bernareggio, aicurzio e bellusco; dallo stesso lobo uno scaricatore di minore portata sfruttava la già esistente valle del rio vallone. dal lobo del lambro, invece, uno scaricatore sfruttava una valle posta a ne di usmate velate. le due piane si univano appena a nord di vimercate, costituendo così un unico sandur di vaste dimensioni. alla glaciazione specola o binago possono essere attribuite anche le ghiaie dell'allogruppo del ponte di paderno che costituiscono corpi interni alla forra dell'adda, in parte cementati e coperti dai successivi depositi dell'allogruppo di besnate. sono attribuiti alla glaciazione binago alcuni affioramenti lungo il rio vallone, che doveva quindi funzionare da scaricatore glaciale, e un grosso terrazzo posto tra concorezzo e vimercate che sottende depositi marcatamente arricchiti in litologie locali. la glaciazione besnate è invece molto più articolata in quanto consta di numerose fasi, ognuna delle quali ha dato luogo a morene e terrazzi variamente giustapposti che sulla carta di fig. 2 sono stati tutti raggruppati nell'allogruppo di besnate indistinto. e' da notare che sia nel lobo del lambro sia in quello dell'adda le morene relative a questa fase si attestano a nord dell'area studiata e, a partire dall'ultima unità dell'allogruppo, uno scaricatore usava la valle dell'adda, tagliando l'alimentazione al rio vallone. allo stesso modo la glaciazione cantù è rappresentata solo da deposti fluvioglaciali che nel lobo dell'adda costituiscono terrazzi interni alla forra e piccole piane a nord di cornate d'adda, mentre nel lobo del lambro (almeno per quanto riguarda il settore in esame) sono limitati a piccoli terrazzi lungo il corso della molgora. l'area a sudovest, come si evidenzia anche dagli schemi dei rapporti stratigrafici, è molto meno articolata. essa è interessata solo dall'incisione delle paleovalli 3 e 4 e da una valle (paleovalle 6) con direzione nw-se. quest'ultima valle è riempita da depositi fluvioglaciali indistinguibili, che comprendono tutta la serie che va dall'allogruppo del bozzente alle prime unità dell'allogruppo di besnate ed è interpretabile in prima approssimazione come un paleoalveo del lambro che scorre attualmente ad appena 2 chilometri di distanza. nello figura 4c è evidente come il tetto dei sedimenti marini si abbassi verso sud e che in questa direzione sia di età più recente rispetto alle aree a nord. questa disposizione è dovuta alla subsidenza della pianura, al sollevamento isostatico della catena e probabilmente anche a tettonica. 7. conclusioni tramite la stretta integrazione tra i dati provenienti dal rilevamento di superficie, dall'analisi di cuttings di perforazione e carote e dalle stratigrafie di pozzi per acqua, è stato possibile ricostruire un modello di sottosuolo dell'area a ne di milano. questo modello supera il tradizionale limite delle ricostruzione di sottosuolo in quanto le correlazioni tra i pozzi non vengono effettuate solo in base alla litologia, ma sono distinti corpi geologici e superfici, riconoscibili grazie al confronto con i dati di superficie. oltre al tracciamento in sottosuolo dei limiti riconosciuti in superficie è stato possibile determinare alcune unità solo sepolte. il lavoro ha permesso di ricostruire un reticolo di valli sepolte oggi totalmente colmato. la definizione delle geometrie dei corpi sepolti inoltre può essere il primo passo verso un migliore e più dettagliato modello idrogeologico, in quanto i limiti tra unità geologiche che spesso hanno diverse caratteristiche idrauliche condizionano la circolazione di acqua nel sottosuolo. la mancanza di una omogenea distribuzione dei pozzi fa si che il modello oggi proposto possa essere migliorato in futuro qualora fossero disponibili ulteriori dati. 8. ringraziamenti si ringraziano tutte le imprese, gli enti e gli studi professionali che hanno messo ha disposizione i campioni e i dati. si vogliono ringraziare in particolar modo il prof. corselli per la determinazione dei macrofossili e davide castradori (agip) per la determinazione del nannoplancton. si ringrazia altresì il dott. peterlongo del c.a.p., il dott. giussani della montedison e il dott. ghezzi dello studio geotecnico associato. 9. bibliografia bini a. (1994) carta geologica dell’apparato glaciale dell’adda (sponda bergamasca) tavola esterna allegata a: cremaschi m., bini a., ferliga c., m a r c h e t t i m., r a v a z z i c. e r o s s i s., 1994: montagna e pianura: i processi geologici recenti e gli effetti sull'ambiente. in: storia economica e sociale di bergamo: i caratteri originali della bergamasca. fondazione per la storia economica e sociale di bergamo. istituto di studi e ricerche. bini a. (1997)a stratigraphy, chronology and palaeogeography of quaternary deposits of the area between the ticino and olona rivers (italyswitzerland). southern alps quaternary geology, igcp 378 meeting, lugano ottobre 1995 geologia insubrica 2 (2), pp. 21-46. bini a., (1997)b problems and methodologies in the study of quaternary deposits of the southern side of the alps. southern alps quaternary geology, igcp 378 meeting, lugano ottobre 1995 geologia insubrica 2 (2), pp. 11-20. bini a. & rigamonti i. (2000) le unità lito e allostratigrafiche dei depositi superficiali. 3.8 il bacino 353geologia di sottosuolo ... dell’adda in: carta geologica della provincia di bergamo, scala 1:50.000 e relative note illustrative, pp. 214-237. provincia di bergamo. caldara m., cancelli a. & giussani a. (1988) the adda canyon, south of lecco: an example of landslide induced morphology. in: bonnard c.: landslides glissements de terrain. proceedings of the fifth international symposium on landslides 10-15 july1988, losanna, vol 1, pp. 89-94. cremaschi m. (1987) paleosol and vetusols in the central po plain (northen italy) a study in quaternary geology and soil developement. unicopoli, milano. denti e., francani v., fumagalli l., pezzera g. & sala p. (1988) studio idrogeologico del foglio vimercate igm 1:50.000 studi idrogeologici sulla pianura padana, 4, pp 2-39. de s i o a. (1938) caratteri fisici e geologici della provincia di milano. ann. sperim. agraria, 32, pp. 3 47. desio a. & villa f. (1960) stratigrafie dei pozzi per acqua della pianura padana. 1-lombardia universita` di milano. ist. di geologia, 370 pp. giussani a. (1992) movimenti franosi profondi e superficiali lungo il naviglio di paderno (f.adda, lombardia) studi trentini di scienze naturali, 68 (1990), pp. 1-24. lorito r. (1997) analisi sedimentologica e paleontologica di alcuni sondaggi eseguiti a cornate d’adda (mi) tesi di laurea inedita. università degli studi di milano. mariani e. (1928) il pliocene del sottosuolo di monza e vimercate (lombardia) atti soc. it. sc. nat., 67, pp. 136-143. maroni m. (1994) studio della stratigrafia di alcuni pozzi profondi nella zona di agrate brianza, brugherio e burago molgora. tesi di laurea inedita. università degli studi di milano. orombelli g. (1979) il ceppo dell’adda: revisione stratigrafica riv. ital. paleont., 85 (2), pp. 573 652. orombelli g. & gnaccolini m. (1978) composizione petrografica e provenienza del "ceppo" di paderno d’adda gruppo di studio quatern. padano, quaderno 4, pp. 7 30. riva a. (1941) notizie sul glaciale della brianza boll. soc. geol. it. 60 (1), pp. 50-64. riva a. (1943) il morenico antico in brianza boll. comit. glac. it., 22, (1942), pp. 1 6. riva a. (1947) commento alla carta geomorfologica 1:30.000 dell’apparato morenico dell’adda di lecco di sergio venzo boll. soc. geol. it., 66, pp. 22-24. r i v a a. (1953) stato attuale dello studio del quaternario del territorio a sud del lario e compreso tra l`adda e l`olona, fino alla latitudine di monza la ricerca scientifica, 23 (2), pp. 226 231. riva a. (1957) gli anfiteatri morenici a sud del lario e le pianure diluviali tra adda e olona atti ist. geol. univ. pavia, 7, pp. 5 95. rossi s. & rigamonti i. (2000) le unità lito e allostratigrafiche dei depositi superficiali. 3.7 il bacino del brembo: in: carta geologica della provincia di bergamo, scala 1:50.000 e relative note illustrative, pp.179-214. provincia di bergamo. strini a. (2001) gli occhi polini della brianza orientale. genesi ed evoluzione del fenomeno nel quadro geologico regionale tesi di dottorato di ricerca, università degli studi di milano, 550 pp. tomasi f., 2001 i depositi plioquaternari tra la valle del torrente lure e la valle del torrente seveso (co) tesi di laurea inedita, università degli studi di milano. ugolinif. & orombelli g. (1968) notizie preliminari sulle caratteristiche pedologiche dei depositi glaciali e fluvioglaciali fra l'adda e l'olona in lombardia rend. ist. lomb. sc. lett., a 102, pp. 767 799. vedrietti f. (1993) analisi stratigrafica di due pozzi situati nel comune di ronco briantino tesi di laurea inedita. università degli studi di milano. venzo s. (1948)a rilevamento geomorfologico dell’apparato morenico dell’adda di lecco atti soc. it. sc. nat., lxxxvii (1947) (1-2), pp. 79 140. venzo s. (1948)b la serie quaternaria dell’apparato morenico dell’adda di lecco comparata col diagramma di milankovitch boll. soc. geol. it., 56 (1947), pp. 82 83. venzo s. (1949) risposta al commento di riva sulla mia carta geomorfologica dell’apparato morenico dell’adda. osservazioni sulla carta geomorfologica tra il canturino e la brianza occidentale, 1949, del dott. arturo riva boll. soc. geol. it., 68, pp. 58 65. venzo s. (1950) rinvenimento di anancus arvernensis nel villafranchiano dell’adda di paderno, di archidiskodon meridionalis e cervus a leffe. stratigrafia e clima del villafranchiano bergamasco atti soc. it. sc. nat., 89 (1/2), pp. 43 122. zuccoli l. (1997) geologia dell’alta pianura lombarda tra i pianalti di castelseprio e tradate appiano gentile tesi di dottorato di ricerca, università degli studi di milano, 453 pp. zuccoli l. (2000) geologia dei pianalti di castelseprio e tradate (provincia di varese) il quaternario, italian journal of quaternary science, 13, pp. 5780. 354 ms. ricevuto l’11 maggio 2004 testo definitivo ricevuto il 2 novembre 2004 ms. received: may 11, 2004 final text received: november 2, 2004. a. bini et al. imp.nisio&scapola individuazione di aree a rischio sinkhole: nuovi casi di studio nel lazio meridionale stefania nisio1 & fabiana scapola2 1apatdipartimento difesa del suolo v. curtatone, 3 00185 roma. e-mail stefania.nisio@apat.it 2stage di formazione apat via littorio19, 03038 roccasecca (fr) riassunto: s. nisio & f. scapola, individuazione di aree a rischio sinkhole: nuovi casi di studio nel lazio meridionale. (it issn 03943356, 2005). distribuiti sul territorio italiano sono presenti molti laghetti di forma sub-circolare originatisi in epoca storica, le cui modalità di formazione, la morfologia e il contesto geologico-strutturale potrebbero essere compatibili con fenomenologie di piping sinkhole. tali laghetti presentano in genere diametro variabile da pochi metri al centinaio di metri e profondità fino ad un massimo di cinquanta metri. su alcuni si narrano leggende che ne farebbero risalire la formazione ad un evento catastrofico. la correlazione tra questi e gli sprofondamenti catastrofici, tipo piping sinkholes, è suggerita dall’osservazione del fenomeno più frequente dopo la formazione di un sinkhole: il processo di “annegamento” della cavità. nella maggior parte dei casi, infatti, le acque di infiltrazione si riversano all’interno della cavità di sprofondamento dandole la fisionomia di un piccolo lago di forma sub-circolare. in altri casi, invece, al fondo della cavità vi sono delle sorgenti che colmano rapidamente la voragine, nell’arco di pochi giorni, alimentandola perennemente. per alcuni fenomeni le ricerche effettuate hanno permesso di acquisire informazioni precise circa la data e le modalità di formazione, come è avvenuto per il lago di caira, nei pressi di cassino, di cui è stato possibile proporre una ipotesi genetica. il lago di caira, non noto sino ad oggi nella letteratura geologica, si è formato in seguito ad un evento calamitoso ed in maniera altrettanto repentina si è ricolmato, dopo circa due secoli. e’ stato possibile effettuare una ricostruzione accurata del contesto geologico, geomorfologico e idrogeologico al contorno nell’area di cassino-caira, e ricostruire la profondità del bedrock. la natura dello sprofondamento risulta compatibile con quella di un fenomeno di erosione dal basso, sinkhole s. s.; la cavità infatti si è originata in un’area di pianura al di sopra di una copertura continentale con spessori superiori a 100 metri. la scoperta della presenza del lago ha suscitato la necessità di indagare a fondo tutto il territorio del lazio meridionale, al fine individuare altri possibili episodi di deep piping. le ricerca hanno confermato che anche nelle aree limitrofe si sono manifestati in passato questi episodi calamitosi. e’ stato, inoltre, individuato un allineamento nne (faglia theodicea) lungo il quale si concentrano questi fenomeni. abstract: s. nisio & f. scapola, sinkhole prone areas: new study cases in southern lazio. (it issn 0394-3356, 2005). many sub-circular ponds in italian territory which originated in historical age, could be due to piping sinkhole phenomena. this hypothesis is supported by the geological, morphological and structural setting of the area affected by the sinkholes. the small lakes have diameters from a few, to hundreds of meters and a depth of up to fifty meters. the names are of dialectical origin and they usually indicate a kind of sinking. some legends refer the origin of the lakes to a quick catastrophic collapse. these depression are usually originated by karst erosion (collapse dolines) and the genetic process could sometimes be related to a deep piping process. the correlation between collapses and piping sinkholes is confirmed by the “drowning” of the cavity soon after the formation. groundwater fills the cavity creating a pond, sometimes with underwater springs that feed the small lake. the identification of a pond as sinkhole is not easy and needs specific studies such as geological surveys, geophysical, geochemical and hydrogeological studies. sometimes it is not possible to make an extensive field survey, due to costs, but it is just possible to suggest some hypotheses. the first step is to verify the geological and structural setting of the area, on the field and from the available literature. in some cases we have found a lot of information on, the date and the modalities of the cave genesis; for example the caira sink. the caira lake, unknown in geological literature, is formed by a collapse and after two centuries it is buried. information about this lake are preserved in few ancient documents in cassino mount abbey. geological, geomorphological and hydrogeological studies have been conducted. some first hypothesis are presented to explain the genesis of caira lake. the origin of the lake is compatible to sinkhole sensu stricto (or piping sinkhole); the lake is originated in a plain area over sedimentary cover (up 100 meters of thickness). after the discovery of the ancient lake, many areas of southern lazio have been investigated. the analysis of the aerial photographs has identified the location of many sinkhole ponds and paleoforms, in the same area. some of which at the present time are still the seat of the ponds and others are dry. from the historical sources the presence of other numerous lakes, now extinct and of difficult location have been verified. examining the concerned area we can conclude that some of these forms have originated from the sinkhole sensu stricto phenomenon. it has also been possible to determine the presence of a nne active fault system (theodicea fault), inside the intermontane basin of cassino, not known in literature. it is along this nne fault system that, in the past there was the distribution of almost all of the springs and/or ponds. at present the major sinkholes develop and align in this area. thanks to these discoveries, this area of southern lazio can be listed among the sinkhole prone risk areas. it is therefore necessary to accomplish a series of detailed technical enquiries before carrying out new infrastructures in order to protect the new constructions and above all human life. parole chiave: sinkhole, sprofondamento, deep piping, lazio meridionale, caira. keywords: sinkhole, sinking, deep piping, southern lazio, caira. il quaternario italian journal of quaternary sciences 18(2), 2005 223-239 224 s. nisio & f. scapola 1. area indagata e scopo del lavoro l’area oggetto di studio ricade nel territorio della provincia di frosinone, si estende per gran parte della valle latina procedendo da sora fino alla confluenza del fiume liri con il fiume gari (fig. 1). i siti indagati sono per lo più depressioni, piane alluvionali e conche intermontane, tutte di origine tettonica: la piana di sora, la conca di cassino, il bacino lirino ed altre piccole piane circondate da rilievi carbonatici. lo scopo del presente lavoro è quello di studiare la situazione geologico-strutturale, idrogeologica e geomorfologica nonché l’evoluzione storica del territorio e l’impatto antropico per individuare un’eventuale concomitanza di fattori predisponenti ed innescanti tale da determinare una reale potenzialità di rischio sprofondamento, sufficiente per classificare questo territorio come una “sinkhole prone area” (area a forte rischio sinkhole). a tal fine è risultato determinante il reperimento di alcune segnalazioni storiche (non note nella letteratura geologica) e l’individuazione di forme di sprofondamento attuali o relitte, per lo più coincidenti con cavità subcircolari, a volte obliterate, e con piccoli laghetti. in quest’area, infatti, sono state riconosciute alcune morfologie, di cui almeno due, rispettivamente presso l’abitato di caira e presso sora, riconducibili a fenomeni di sprofondamento repentino entrambe sedi di laghi oggi prosciugati: il lago di caira (che sarà l’oggetto principale di questa trattazione per la maggiore quantità di dati raccolti) ed il lago tremoletto, tra carnello e località s. domenico. tra gli altri specchi d’acqua rinvenuti meritano attenzione il lago di acquasanta e la polla magnesiaca. sono state individuate inoltre alcune paleoforme, con l’ausilio della fotointerpretazione, di cui solo ad alcune è stato possibile attribuire l’identità di cavità di sprofondamento o di sinkhole ponds, dopo la verifica sul terreno, (tra cui la pescarola, la cavità che ospita la sorgente magnesiaca e il laghetto di acquasanta), per altre, ormai, morfologicamente obliterate, non sono rimaste tracce neanche nella memoria storica degli abitanti e dei luoghi. 2. i fenomeni di sinkhole nel panorama italiano a differenza di numerosi altri eventi catastrofici generati da calamità naturali, fino a qualche decennio fa l’apertura di improvvise voragini nel territorio occupava un posto marginale nei programmi di protezione civile e di pianificazione territoriale. ultimamente, a causa della forte antropizzazione, il “rischio totale” associato al verificarsi di tali sprofondamenti è aumentato notevolmente fino al punto di suscitare l’attenzione non solo degli enti preposti alla tutela del territorio ma anche, di conseguenza, dell’intera comunità scientifica per un’azione di previsione e prevenzione degli stessi. il rischio associato all’innescarsi di dette fenomenologie è strettamente collegato non solo all’intensità e alla pericolosità dell’evento in sé, ma soprattutto alla corretta valutazione e determinazione degli “elementi” a rischio (vite umane, beni immobili, infrastrutture, strutture adibite a pubblico servizio e soccorso, beni culturali ecc). i sinkholes, forme di erosione che si inseriscono nell’ambito di processi di sprofondamento catastrofico, consistono in depressioni morfologiche sub circolari che si formano in seguito allo sprofondamento repentino di una porzione di terreno (f airbridge, 1968; monroe, 1970). il termine sinkhole spesso indica forme crateriche o pseudocrateriche omologhe ma generate ed evolute secondo modalità differenti. nella letteratura anglosassone il termine è sinonimo di dolina o di sprofondamento di origine antropica. in italia definisce forme di erosione dovute non solo a fenomeni carsici o gravitativi, ma anche forme più peculiari, che si formano in aree di pianura su grandi spessori di copertura sedimentaria, dovute all’interazione tra: risalita dal basso di fluidi di provenienza profonda, rocce carbonatiche, falde superficiali ed acque di infiltrazione meteorica, oscillazioni del livello di falda ed attività tettonica attiva e recente (nisio, 2003; nisio & salvati; 2004; nisio et al., 2004, 2005; ferreli et al., 2004). gli elementi che distinguono una dolina da un sinkhole in senso stretto sono le condizioni geologiche fig. 1 schema geologico dell’area e ubicazione di altri fenomeni, sinkhole pounds o paleoforme, individuati nell’area di cassino-s. eias. giorgio al liri (da devoto, 1965 modificato). location of the other phenomena recognized (sinkhole pounds o paleoform) in the cassinos.elia-s. giorgio area (from devoto, 1965 modified). al contorno, le modalità di innesco e di propagazione del fenomeno (salvati & sasowsky, 2002; nisio, 2003; nisio & salvati, 2004; nisio et al., 2004). la propagazione del processo si sviluppa, contrariamente a quanto avviene per le doline, dal basso verso l’alto fino a coinvolgere la copertura che si trova al di sopra del substrato carbonatico sottoposto alla dissoluzione carsica (per ulteriori approfondimenti si rimanda comunque a letteratura più specifica sull’argomento faccena et. al. 1993; tharp, 1999; berti et. al., 2002; regione toscana, 2002; salvati & sasowsky, 2002; nisio, 2003; nisio & salvati, 2004 etc.). i sinkholes s.s. si originano in contesti geologicostrutturali ed idrogeologici abbastanza articolati e complessi. zone ad elevato rischio sono le piane alluvionali e le conche intramontane in contatto con successioni carbonatiche, intensamente carsificate e tettonizzate (che ne costituiscano il bedrock), nelle quali vi sia la presenza concomitante di alcuni o tutti i fattori predisponenti e innescanti (faccenna et. al., 1993; capelli et. al. 2000; nisio, 2003; ferreli et. al., 2004). nella maggior parte dei casi finora individuati si è riscontrato che tali fenomeni tendono a concentrarsi in corrispondenza di aree caratterizzate da un’abbondante circolazione d’acqua, ove sono presenti acquiferi imprigionati in substrati profondi per lo più ricoperti da sedimenti impermeabili o scarsamente permeabili ed entrambi interessati da sistemi di faglie. quest’ultimi mettono in comunicazione idrica i due mezzi favorendo processi di sifonamento, suffosione profonda (deep piping) ed erosione preferenziale, specialmente nella zona di interfaccia (littlefield et. al., 1984; derbyshire & mellors, 1988; billiard et. al., 1992; nisio, 2003; nisio et al., 2005). i processi di deep piping rivestono un ruolo fondamentale nell’origine dei sinkhole s.s. per tale motivo a questi è stato dato anche il nome di piping sinkhole o meglio deep piping sinkhole (nisio, 2003; nisio & salvati, 2004; nisio et. al. 2004; 2005; graciotti et. al. 2004). molte aree dell’appennino centro-settentrionale e meridionale sono interessate da questi fenomeni; triste primato spetta proprio alla regione lazio, in cui gli sprofondamenti risultano concentrati in conche intramontane (ad es. la piana di s. vittorino, rieti), in strette valli fluviali (es. valle del f. s. martino, capena), in piane costiere (es. pianura pontina), nonché in depressioni e fasce pedemontane di aree vulcaniche (faccenna et. al., 1993; bono, 1995; di loreto et. al. 1999; capelli et. al. 2000; ciotoli et. al., 2001; colombi et al., 2001; bersani & castellano, 2002; nisio, 2003; annunziatellis et. al., 2004; del prete et. al., 2004; graciotti et. al., 2004). inoltre su molte piane del territorio italiano, soprattutto in appennino, sono presenti piccoli laghi, polle o fosse di forma circolare (craterica o pseudo-craterica) di dubbia origine che potrebbero essere compatibili con tali fenomeni (caramanna et. al., 2004; del prete et. al., 2004; nisio et. al. 2005). molti fenomeni di sinkholes sono stati segnalati nelle vicinanze dell’area di studio, in un raggio di circa 100 km: sul versante sud-orientale del roccamonfina, e nella valle del f. volturno, presso il confine lazio-campania (del prete et. al., 2004); presso posta-fibreno (frosinone; agrillo et. al., 2004), nelle vicinanze di atina (saroli et. al., 2004); nonché più a sud in pianura pontina (norma225individuazione di aree a rischio ... sermoneta-sezze; bono, 1995; colombi et. al. 2001; di filippo et. al., 2002; nisio, 2003; campobasso et. al., 2004). fenomenologie di sinkhole non erano prima d’ora state segnalate nell’area del cassinate. 3. inquadramento geologico–strutturale le aree di pianura in studio ricadono nel lazio meridionale, coincidono con le piane di cassino e sora e con una parte della piana alluvionale del lirigarigliano, alle pendici di alcune dorsali carbonatiche tra cui quella di monte cairo (provincia di frosinone; fig. 1). dopo la tettonica compressiva, che ha portato alla costruzione dell’edificio a thrust, una fase estensionale ha prodotto in quest’area una rete di faglie normali ad alto angolo, immergenti, generalmente, verso ovest, molte delle quali riattivano i vecchi piani di thrust sepolti (ghisetti & vezzani, 1999; cavinato & de celles, 1999). si impostano, nel versante sudovest della catena, numerosi bacini estensionali, tra cui il bacino di sora, con una geometria ad half-graben delimitati dalle suddette faglie, ripetutamente riattivate durante il pliocene sup.pleistocene, con rigetti, per le strutture maggiori, fino a uno/due chilometri (ghisetti et. al., 2001). i bacini, colmati da sedimenti di syn-rift dal miocene sup. al pleistocene inferiore, presentano un’orientazione nnw-sse e nw-se; altri, di dimensioni minori, a direzione ne-sw o n-s (tra cui il bacino di cassino), si sono sviluppati come strutture trasversali (mattei et. al., 1994). durante il pleistocene l’area emerge ed una fase tettonica distensiva genera bacini interni fluvio-lacustri con connesse manifestazioni vulcaniche (roccamonfina), controllati da strutture appenniniche ed antiappenniniche. nel pleistocene medio si verifica una nuova fase distensiva che porta all’estinzione dei bacini lacustri, alla formazione di nuove conche interne e alle attuali morfostrutture. dal pleistocene superiore è attiva una tettonica tipo strike-slip che ha dato localmente origine a piccoli bacini tipo pull-apart, sorgenti termominerali, deposizione di travertini e caratteristiche vulcano-tettoniche (faccenna, 1994; mattei et. al., 1994). in questo contesto si è formato il “bacino lirino” che è stato colmato da depositi lacustro-alluvionali (con spessori di oltre 100 m) posti in contatto tettonico con la successione carbonatica mesozoica che costituisce l’ossatura del massiccio affiorante. esso si estende nell’ambito delle province di frosinone e di caserta, presenta una direttrice morfostrutturale nw-se, fra la catena dei monti aurunci (a sud-ovest) e la catena dei monti simbruini-monte cairo (a nord-est), a confine fra l’appennino centrale e quello meridionale. la nascita e lo sviluppo del bacino lirino sono stati, fin dai primi studi, attribuiti sia all’attività di sistemi di faglie appenniniche, a carattere prevalentemente distensivo con notevoli rigetti verticali, che al sorgere dell’edificio vulcanico del roccamonfina (devoto, 1965; damiani & panuzzi, 1980, 1982; cavinato et. al., 1995). all’interno di quest’area si distinguono tre sistemi di faglie principali: n-s, nw-se ed e-w. le faglie che ne bordano il margine nord-orientale, ai piedi sia di 226 monte cairo che dei monti di venafro, sono normali ad alto angolo; mentre la linea tettonica che borda il margine sud-occidentale, fra pico, esperia e m.te fammera, è un piano di faglia inverso (un sovrascorrimento) a direzione nw-se immergente verso sud, a basso angolo (cerisola & montone, 1992). i rilevamenti hanno messo in luce l’esistenza di un terzo elemento tettonico di importanza probabilmente “regionale” (confermato anche dal confronto dei dati di rilevamento con i sondaggi geognostici reperiti), qui definito faglia theodicea (passante presso s. angelo in theodice; fig. 1). osservazioni geomorfologiche, strutturali e stratigrafiche, accompagnate da indagini geofisiche, suggeriscono una ripartizione del bacino lirino in due settori, uno occidentale (ad ovest del fiume gari) caratterizzato da un regime estensionale a direzione prevalentemente ne-sw ed uno orientale caratterizzato da un regime sempre estensionale ma a direzione prevalentemente wnw-ese. la faglia theodicea, a direzione nne, potrebbe servire da svincolo fra questi due settori a mobilità diversa e, quindi, non si possono escludere movimenti trascorrenti lungo la stessa. i settori orientali in prossimità del fiume gari sono ribassati, rispetto a quelli occidentali, dall’attività del sistema nne più giovane rispetto a quello wnw e nw. la piana di cassino-caira a nord-est è delimitata dalla faglia della marsica, che interessa i monti di venafro e monte cifalco, ad ovest dalla faglia theodicea (nne) e a sud dall’allineamento monte trocchio-monte porchio, che sembra essere una prosecuzione sud-orientale della faglia che mette in contatto monte cairo con i sedimenti lacustri ed alluvionali che colmano la valle latina (accordi, 1964; parlotto, 1970; 1971; p arlotto & p raturlon, 1975; 1981). questo forte controllo tettonico e l’intensità delle deformazioni fragili ad esso associate hanno provocato un’intensa disarticolazione del substrato carbonatico (cerisola & montone, 1992). in effetti dai numerosi dati di pozzo si nota che la profondità del bedrock varia, anche in aree ristrette, da poche decine di metri dal piano di campagna, nei pressi della dorsale carbonatica, fino a diverse centinaia di metri al centro della piana. le unità litostratigrafiche, che formano i rilievi carbonatici presenti nell’area (m. cairo m. cifalco m. ausoni-aurunci rilievo settentrionale di m. massico), vengono collocate nel dominio di piattaforma lazialeabruzzese (accordi et. al.,1988) a cui si sovrappongono sedimenti terrigeni. al di sopra dei depositi marini e continentali, già morfologicamente modellati, di età plio-pleistocenica poggiano i sedimenti lacustri lirini. l’intera sequenza stratigrafica lacustre, non ancora conosciuta nei dettagli; presenta uno spessore complessivo di cento metri circa. dal punto di vista stratigrafico devoto (1965) suddivide la suddetta successione in tre formazioni principali che sono, dal basso verso l’alto, il limo lacustre inferiore, la facies lacustre normale e la facies lacustre tardiva. a queste l’autore aggiungeva, oltre ai travertini tipici, le facies vulcaniche rappresentate dalle tufiti di vandra, dai tufi cineritici e dai tufi rimaneggiati di san vittore (fig. 1). il limo lacustre inferiore presenta grande uniformità, è composto da limi calcarei molto puri, a giacitura orizzontale, ad alto tenore in caco3 (circa l’80/90%) regolarmente intercalati da numerosi livelli, a spessore variabile, di prodotti vulcanici. lo spessore totale affiorante è di circa 25-30 m. la facies lacustre normale è la più rappresentativa dei depositi lacustri lirini, complessivamente è costituita da un 60% di ghiaia-sabbia, da un 30% di limi calcarei e per il restante 10% da altre tipologie di sedimenti, presenta una significativa varietà di litofacies ed un’estrema variabilità del contenuto in caco3 che oscilla fra il 20% ed il 98%. la facies lacustre tardiva è composta prevalentemente da limi calcareo-argillosi, da limo torboso, da sabbie calcaree, da travertini incoerenti e da travertini porosi inglobanti resti vegetali palustri. significative sono le variazioni delle percentuali di sabbia e di argilla nei singoli strati. la deposizione del travertino tipico (che affiora solo in alcuni punti della piana; carrara, 1991) è connessa con l’attività di sorgenti fortemente incrostanti ad elevato tenore in ca++ e mg++ alcune delle quali sono tuttora attive (capo d’acqua). i principali sistemi di faglie che hanno interessato l’area sono due: il primo sistema presenta allineamento nw-se a cui sono collegate le placche di travertino presenti fra aquino – cassino, ed il secondo, orientato circa n-s o nne-ssw alla cui attività vengono attribuiti sia gli affioramenti rinvenuti presso la direttrice pontecorvo-aquino che quelli lungo il corso del fiume gari in s. angelo in theodice. benché le bancate di travertino si ritrovino in maniera frammentaria in tutta l’area, si è ipotizzata l’esistenza, su base morfologica, di un solo grande affioramento il cui spessore raggiunge i 18m. di norma i travertini tipici seguono o sono incassati nei sedimenti lacustri del lago lirino mentre, lungo il margine nord-orientale, poggiano sulla sequenza carbonatica della piattaforma laziale – abruzzese. da un punto di vista composizionale la litofacies, per lo più vacuolare, è caratterizzata da alternanze di sabbie e limi calcarei, contenenti litotipi autoctoni micro e fitotermali associati a facies stromatolitiche e bibliolitiche. di frequente dal travertino litoide si passa a quello spugnoso ed incoerente. al di sopra dei sedimenti lacustri affiorano, per lo più, alluvioni antiche e recenti, detriti di falda e/o di versante e terre rosse. riportiamo, qui di seguito, una colonna stratigrafica “tipo” per la piana di cassino, ricordando comunque che la profondità del substrato carbonatico oscilla notevolmente fra il piano campagna ed i 150 m, allontanandosi dai bordi verso il centro della piana (i dati sono stati riassunti nelle stratigrafie di fig. 7b): 0/4 m terreno vegetale; 4/15 m grosse alternanze di limo con argilla, sabbia e sabbia con ghiaia; 15 m/15,5 m ghiaia grossolana; 15,5 m/16,7 m limo poco argilloso, grigio chiaro; 16,7 m/17,0 m ghiaia grossolana; 17,0 m/ 18,5 m: limo con argilla, bruno; 18,5 m/22,0 m: sabbia media grossolana; 22,0 m/23,4 m: limo argilloso e sabbioso con poca ghiaia minuta, grigio; 23,4 m/43,5 m: limo con argilla, da grigio scuro a bruno (prelevato campione indisturbato c1 a 26m); 43,5 m/48,0 m: limo poco argilloso con tracce di sabbia fine, grigio chiaro; 48,0 m/51,5 m: limo poco argilloso con tracce di sabbia fine, grigio (prelevato campione indisturbato c2 s. nisio & f. scapola 227 a 50m); 51,5 m/60,5 m: limo con argilla, grigio; 60,5 m/67,8 m: limo argilloso, debolmente organico, con elementi di ghiaia, da grigio scuro a bruno; 67,8 m/103 m (fondo foro): calcari biancastri. 3.1 sismicità dell’area nella zona di montecassino si sono sempre verificati fenomeni particolari (“i terremoti locali di montecassino”) che turbavano molto sia gli abitanti che i monaci della badia. questi ultimi, non sapendo dare una spiegazione scientifica del fenomeno, si limitarono a riportare fedelmente la descrizione. la cronistoria “sismica” di montecassino, registrata dai monaci della abbazia, inizia nel 1005 e, tranne qualche piccola lacuna, giunge fino al 1920. dal 1005 al 1887 si registrarono ben 453 terremoti ma, nel 1920, sacchetti annotava che “la quasi totalità dei terremoti subiti rimase circoscritta a montecassino e solo raramente fu avvertita a cassino”. i monaci chiesero al re di napoli, ferdinando ii di borbone, di far studiare da un geologo del regno le cause dei tremori ai quali si associava un odore di zolfo. il re, nel 1837, incaricò leopoldo pilla che imputò i terremoti a fattori “locali” e li ascrisse a cause elettriche. de marco, invece, nel 1888, arriva alla conclusione che tali scosse sono imputabili a crolli dovuti all’azione aggressiva delle acque sotterranee. sacchetti (1920) sostenne la tesi di de marco riportando, a supporto della stessa il “terremoto che nel 1724 si verificò“al paesello di cairo” (data coincidente con la formazione del lago di caira) e precisando che non si trattò di una vera e propria scossa sismica. gli episodi descritti sono in definitiva da ricollegare ai fenomeni carsici presenti sulla dorsale di monte cairo che portano alla frequente formazione di doline di crollo e all’allargamento di cavità ipogee, processo peraltro molto spinto ed ancora visibilmente in atto. l’area in esame tuttavia è stata colpita da diversi sismi di forte intensità (istituto nazionale di geofisica, 2000). in particolare la zona compresa fra la valle latina e il confine con la campania (da sora al vulcano di roccamonfina) appare decisamente attiva soprattutto per l’elevata frequenza degli eventi registrati, con un addensamento anomalo proprio in corrispondenza del territorio di cassino. (gasparini et. al., 1985; frezzotti et. al., 1988; frepoli & amato, 2000). l’area con elevato risentimento è allungata lungo la direzione nw-se. tra gli eventi della sismicità storica dell’area si ricorda quello del 9 settembre del 1349 che colpì il cassinate ed il territorio di isernia (a cassino il risentimento è stato del ix grado), quello del giugno 848 nel sannio occidentale, quello del 23 luglio del 1654 nell’area sorano-marsicana che provocò la completa distruzione delle località di piedimonte san germano alta, posta fibreno e santopadre, ed infine l’evento del 6 dicembre 1874 dei monti della meta. nel 1724 si verificarono solo due scosse nei mesi di settembre e ottobre. tra gli eventi sismici recenti, i più significativi sono: un evento del 1973 (di magnitudo 4.4 localizzato a 5 km di profondità), un evento del 1980 (di magnitudo 3.5 con ipocentro a 8 km di profondità) e i due terremoti del 7 e del 11 maggio del 1984 che colpirono l’area compresa tra l’alta valle del sangro, san donato in val di comino ed i monti della meta, di magnitudo mb 5.5 e 5.3, rispettivamente. i danni del sisma si riscontrano nell’area di studio lungo l’allineamento rappresentato dalla faglia theodicea (su cui è ubicato il sinkhole di caira); il piezometro ubicato nella villa comunale di cassino (distante circa 1.5 km dal lago di caira sul medesimo allineamento) si abbassò di molti centimetri ulteriori eventi sismici sono stati registrati nel giugno e nel settembre1994, e gli effetti si registrano anche sugli allineamenti in direzione n-s (frepoli & amato, 2000). inoltre scosse strumentali registrate tra il 2003 e il 2004 nell’area di cassino hanno determinato abbassamento del suolo (registrato presso un piezometro) di circa 3 centimetri a poca distanza dal lago di caira, e lungo l’allineamento nne di cui si è parlato in precedenza. ultimamente l’istituto nazionale di geofisica e vulcanologia ha rilevato, durante il monitoraggio della rete sismica nazionale centralizzata, il verificarsi di un periodo sismico. tali eventi sismici avvertiti dalla popolazione locale e, peraltro, segnalati alla protezione civile, presentano profondità ipocentrale molto superficiale dando luogo a boati e a risentimenti macrosismici molto localizzati. 4. evoluzione geomorfologica nel pliocene la porzione sud-orientale dell’odierna valle latina era interessata da una sedimentazione caratteristica di ambiente marino costiero e doveva presentarsi come un golfo aperto in direzione ese fino al pliocene medio-superiore, (fig. 2). durante la fase regressiva le acque lasciarono definitivamente l’area compresa fra le dorsali carbonatiche. il rapido abbassamento del livello del mare dovette incidere profondamente sull’organizzazione dei reticoli idrografici preesistenti ed il settore appena emerso divenne una valle fluviale sbarrata in seguito alla costruzione del vulcano di roccamonfina. nel pleistocene medio iniziò la raccolta delle acque del lago lirino (devoto, 1965). l’aumento del carico sedimentario con l’erosione della soglia operata dall’emissario (l’attuale garigliano), hanno fatto del lago lirino un lago precocemente fossile. infatti, dato il continuo sollevamento a cui è stata soggetta quest’area, gli immissari furono costretti ad operare un continuo “ringiovanimento” del loro profilo d’equilibrio; cosa che determinò un apporto talmente massivo di sedimenti da ottenere, come effetto, il rapido colmamento del bacino stesso. l’età di estinzione del sistema lacustre lirino potrebbe essere avvenuta 368 ka (evernden e curtis; 1965) o 354±7 ed i 359±7 ka (narcisi; 1986). terminato il ciclo lacustre il principale agente morfologico divenne quello fluviale; ai sedimenti “lirini” si sovrapposero i depositi alluvionali. l’ultimo ordine di terrazzi, post-würmiano, si situa a pochi metri dall’attuale letto del liri. la piana di cassino presenta versanti regolarizzati ad est ed ad ovest ed è orlata, nel margine settentrionale, da piccole conche intermontane la cui genesi è strettamente collegata alla presenza ed alla attività di elementi strutturali il più delle volte a direzione ns. il massiccio carbonatico affiorante, oltre ad essere visibilmente fratturato e tettonizzato, presentandosi a luoghi pulverulento, è anche intensamente carsificato. individuazione di aree a rischio ... 228 presso monte cairo-monte cassino è emersa la presenza di numerose doline per crollo o dissoluzione (di grande diametro) la cui distribuzione sembra ricalcare l’andamento delle faglie principali. all’interno della conca si individuano numerose conoidi detritiche a ventaglio di notevoli dimensioni, disposte prevalentemente lungo la faglia della marsica e, subordinatamente, lungo la faglia theodicea (in località caira). anche il reticolo idrografico e la distribuzione delle sorgenti risentono del controllo tettonico. e’ evidente in quest’area la regolarizzazione di tratti o di intere aste fluviali (ad es.fiume rapido e parte del fiume gari) che assumono un andamento circa ns ricalcando l’andamento della faglia theodicea. la ricostruzione della rete di drenaggio superficiale, ordinata secondo il metodo di strahler (1954), ha permesso di ricavare indizi morfotettonici: anomalia significativa è rappresentata dalle aste dei primi ordini che tendono ad assumere un’orientazione preferenziale nw-se, tale distribuzione ha un addensamento in corrispondenza della diagonale nw-se tracciabile fra la confluenza del fiume liri con il fiume gari e massoneria di folco (aquino). anche le forme d’aquino presentano in quest’area una rettizzazione nw-se, preceduta da una “cattura a gomito”, del loro corso. questi indizi, associati alla constatazione che tale direttrice funge anche da spartiacque fra il settore nordorientale e quello sudoccidentale, fanno pensare alla presenza di una faglia sepolta avente la medesima orientazione. in effetti le aste dei primi ordini, essendo le più “giovani” non sono controllate dalle “vecchie direttrici tettoniche” ma da quelle recenti e/o attuali. l’azione della tettonica è altresì testimoniata dalla presenza di forme strutturali sui versanti quali: faccette triangolari, depressioni, selle e interruzione di linee di cresta. 5. risorse idriche dell’area: studi sulla migrazione e sulla variazione di portata delle sorgenti l’area in studio è caratterizzata da un abbondante flusso di acque sia superficiali che profonde. quest’ultime vanno ad alimentare, in maniera considerevole, le portate dei corsi principali. l’unità idrogeologica, che dà origine alle sorgenti del gari, appartiene a quella più grande, costituita dai monti ernici, dai monti simbruini e da monte caira, e ne rappresenta la terminazione meridionale a partire dal fiume cosa (baj & tartaglia, 1973; boni, 1973; mounton, 1973; celico; 1976; celico & stanganelli, 1976; boni et al., 1986). a sud della linea del cosa sono presenti altri due punti di sfioro della falda che costituiscono, rispettivamente, le sorgenti di capodacqua d’aquino e di bucone (fig. 3). le prime sono legate alla discontinuità tettonica della valle del melfa, le seconde all’innalzamento del complesso dolomitico in corrispondenza di monte cairo. caratteristica non trascurabile delle sorgenti bucone è che esse sono costituite da due polle, una sulfurea a circuito lento e profondo e l’altra non sulfurea a ricambio veloce. le sorgenti presenti nell’area di cassino possono essere raggruppate in tre gruppi principali: il gruppo pedemontano, il gruppo delle terme varroniane ed il gruppo mastronardi (fig. 3) con valori di portata cumulati pari a 18m3/sec. le acque di tali sorgenti confluiscono nel fiume gari incrementandone la portata. la conca di cassino è attraversata dal fiume rapido (che presenta portata media di 2.5 m3/sec) nelle cui acque vanno a confluire i torrenti che attraversano il territorio di cassino-caira fra cui ricordiamo il torrente calcara, il torrente del campo, il fosso della grotta ed il fosso di caira. il rapido si immette nel gari in prossimità del gruppo mastronardi (fig. 3). le sorgenti presenti nel territorio di cassino (s.l.) sono numerose e con elevata portata. durante il corso della storia esse hanno subito variazioni per numero, ubicazione e chimismo (varrone, 1954). attualmente è diminuito il numero delle sorgenti minerali la cui presenza ed azione massiva nei tempi passati sono testimoniate litilogicamente dalle bancate di travertino, che occupano gran parte della piana, e documentate da numerose fonti storiche e bibliografiche. la maggior parte delle sorgenti minerali sgorgava fra valle faga e suio, ma ve ne erano diverse anche nel territorio di cassino nei pressi della badia, in località s onofrio ed anche in località fontanelle (fra il colosseo e la cappella di santa scolastica). in particolare in località fig 2 ricostruzione paleogeografica dell’area. paleo-geographic reconstruction of the study area. s. nisio & f. scapola fontanelle erano presenti due polle, una d’acqua sulfurea e l’altra ferruginosa con temperatura di 15°c (sacchetti 1920). queste polle minerali rappresentavano ciò che rimaneva di una serie più numerosa che fino al secolo decimo ottavo alimentava il ramo del fiume rapido (gattola 1734); fra queste ricordiamo le due sorgenti presenti nei pressi del lago di caira; fig. 3). il numero delle sorgenti d’acqua dolce era numeroso ed imprecisato (pilla, 1815), si pensi che nel 1902 del foco ne elenca più di quaranta per il solo centro abitato. la distribuzione delle sorgenti sul territorio non sembra casuale ma si individuano allineamenti lungo direttrici tettoniche ben precise. quelle sulfuree (gattola; 1734) si disponevano lungo il corso del rapido (dove lo stesso assume un andamento circa ns) ricalcando la direttrice della faglia theodicea. devoto (1965) descrive l’attività di sorgenti fortemente incrostanti ad elevato tenore in ca++ e mg++ (ad esempio quelle di capo d’acqua) la cui disposizione coincide con l’andamento dei principali sistemi di faglie: il primo ad andamento nw-se, a cui sono collegate le placche di travertino presenti fra aquino e cassino, ed un altro orientato circa n-s o nne-ssw, alla cui attività vengono attribuiti sia gli affioramenti rinvenuti presso la direttrice pontecorvo-aquino che quelli lungo il corso del fiume gari in s. angelo in theodice. un’ultima annotazione riguarda la migrazione delle sorgenti sulfuree che si sono spostate progressivamente dai settori se (cassino, sant’angelo), prossimi all’apparato del roccamonfina, verso quelli nw (isola liri, ceprano) ove attualmente si assiste a periodiche manifestazioni sulfuree. tale migrazione di sorgenti è stata accompagnata da un abbassamento delle vecchie linee sorgentizie, in località caira, di almeno cinquanta metri e da oscillazioni continue del livello di falda. oltre alle probabili cause naturali la spiegazione del fenomeno va ricercata anche in quelle antropiche: quest’area è sottoposta a continui emungimenti (per portate “dichiarate” di 3m3/sec, ma sicuramente più cospicue), resi più intensi negli ultimi 20 anni. tale captazione di acque sotterranee, in un’area prossima alla confluenza del rapido con il gari, aveva avuto approvazione per portate di 6m3/sec. fra l’agosto del 1986 ed il settembre dell’87, a seguito dell’emungimento di 1,5m3/sec si registrarono nel territorio di cassino continui “assestamenti” accompagnati da tremori, alcune sorgenti si estinsero, altre diminuirono notevolmente la loro portata ma, cosa più grave, si verificò la subsidenza di una vasta area e vennero denunciate lesioni a diversi manufatti. dopo perizie tecniche e studi congiunti, le autorità dichiararono che per portate pari a 3m3/sec non ci sarebbero stati risentimenti o rischi significativi per il territorio; tali dati risultarono dagli accertamenti delle condizioni geologico-strutturali al contorno ed dai parametri geotecnici dei terreni analizzati. 5.1 le falde della piana di cassino nei sedimenti di copertura della piana di cassino, caratterizzati dall’alternanza di orizzonti per lo più impermeabili (argille o limi argillosi) con altri a media/alta permeabilità (sabbie grossolane e ghiaie), si rinvengono falde sovrapposte (riscontrate a 25 m e a 40 m di profondità negli strati a buona permeabilità orizzontale). la stessa successione quaternaria, presentando una quasi totale impermeabilità verticale, permette la presenza, nel substrato carbonatico, di un acquifero confinato o falda in pressione. le connessioni idrauliche tra la falda profonda e le diverse falde superficiali avvengono, per lo più, attraverso strati limoso-sabbiosi, a luoghi ghiaiosi, a bassa trasmissività. solo localmente e in aree ristrette, la falda profonda è direttamente in comunicazione con quella superficiale. questo è possibile per la presenza di depositi grossolani posti o al tetto dell’acquifero calcareo o intercalati nei sedimenti fluvio lacustri. connessione tra la falda profonda e quella superficiale è possibile per la presenza di importanti dislocazioni tettoniche (quali la faglia theodicea per esempio), che attraversano sia il substrato che le coperture quaternarie, accompagnate da un reticolo di ripetizioni, di fratture o diaclasi, che mettono in comunicazione il mezzo permeabile carbonatico profondo con quello impermeabile di superficie. 5.2 caratteristiche geotecniche dei terreni di copertura le analisi di due campioni (c1, a 26 m dal p.c, e c2 , a 46 m del pozzo 1, fig 7b) mostrano che i terreni lacustri recenti della piana di cassino sono formati in massima parte da terreni coesivi inorganici (limo con argilla, argilla con limo e limo argilloso) e in minima parte da intercalazioni e lenti di terreni non coesivi (ghiaie più o meno sabbiose e sabbie). fra i terreni coesivi prevalgono le argille inorganiche di 229 fig. 3 schema idrogeologico semplificato dell’area di cassino. ubicazione dei principali gruppi di sorgenti e relative portate.. simplified hydrogeological scheme of the cassino area. location of the main springs groups in the cassino area. individuazione di aree a rischio ... elevata plasticità, seguite in ordine decrescente da limi di medio-bassa plasticità. il contenuto d’acqua del terreno varia generalmente tra il 20% e il 50%. il peso di volume allo stato naturale è in generale compreso tra 1,7 e 2 g/cm3, con valori medi che tendono ad addensarsi intorno a 1,0 g/cm3. i valori medi tra w0 e γ non mostrano alcuna tendenza a variare con la profondità. la coesione non drenata è risultata per entrambi i campioni più elevata di quanto non fosse lecito aspettarsi in base alle ben note correlazioni sperimentali con l’indice di plasticità e con la pressione di consolidazione: fatto questo che starebbe ad indicare un certo grado di consolidazione nei depositi in esame, confermato, tra l’altro, anche dalle prove edometriche. 6. i fenomeni di sprofondamento nel lazio meridionale dall’analisi storica, effettuata presso gli archivi di alcune abbazie e presso biblioteche specialistiche, è emerso che l’area della provincia di frosinone coincidente con le antiche proprietà benedettine prendeva il nome, agli inizi del 1800, di terra dei laghi. ciò per la presenza di una serie di laghetti fra cui ricordiamo: lacus raedemprandi; lacus sapatini; lacus maiore (presso aquino) già presenti nel 1734; lacus de pobilu in area non precisata sulla linea di confine con il territorio di venafro all’interno delle proprietà benedettine; lacus vitecosum; lacus acquafondata (presso viticuso e venafro; jandolo, 1966). altri numerosi laghi, oggi scomparsi, sono emersi dall’analisi toponomastica dell’area in studio, consultando gli atti di compravendita delle proprietà benedettine, relative al periodo 16001800 (leccisotti & avigliano, 1977): la cisterna, la cisternola, pescorile, lo lago, lago di sotto, acqua nera nei pressi di s. elia fiumerapido; le pantane nel territorio di cervaro; lo lacozzo, la pescarola, le pescie, la puzza e caput casini (nelle vicinanze della chiesa di s. pietro), lo lacozzo, lo lago, lo pantano, presso san germano (attuale cassino); le pantanella presso l’abitato di piumarola nella valle del liri. della maggior parte di tali laghi oggi non vi è più traccia, fatta eccezione per la pescarola, in località masseria chiusavecchio. la ricerca storica, pertanto, è stata volta alla possibile ubicazione di tali laghetti e al censimento di eventuali cavità sub-circolari che potrebbero far ipotizzare episodi di sprofondamento del terreno (fig. 4). i documenti storici, unitamente alla fotointerpretazione hanno così portato all’individuazione di una serie di specchi d’acqua e di possibili morfologie depresse nelle aree di pianura: laghetti, piccole polle, con caratteristica forma sub-circolare, cavità asciutte relitte, che si rinvengono al centro di piane alluvionali o conche intermontane, privi di immissario o emissario, e che non possono essere attribuiti ad attività antropiche e/o a fenomeni carsici in senso stretto. la conferma dell’esistenza di tali fenomeni è avvenuta con il reperimento della documentazione storica riguardante la formazione di un lago oggi estinto: il lago di caira. 6.1 il lago di caira l’antico lago di caira (presente dal 1724 al 1904), attualmente estinto e trasformato in vivaio della forestale, è ubicato a valle dell’abitato di caira, frazione di cassino (fig. 5). si colloca quasi alla confluenza fra il torrente calcara ed il fiume rapido sul limite morfologico della conoide alluvionale sulla quale si è sviluppato il paese. lo sprofondamento che diede origine al lago di caira viene riportato in letteratura da numerose fonti che fanno, comunque, riferimento alle notizie riportate dal “giornale cassinese” dell’epoca, e successivamente raccolte nelle “historiae” di gattola (1733; 1734). in queste fonti si ritrova la seguente descrizione (riportata in latino e tradotta dalle scriventi): in questo anno 1724, non lontano da caira nella notte fra il 18 e 19 febbraio 230 fig. 4 tentativo di ubicazione di alcuni laghetti, oggi estinti, rinvenuti su mappe storiche del 1715 e 1734 e principali allineamenti. hypothesis of location of some buried lakes and ponds recognized on historic maps (1715 and 1734) and principal alignments. fig 5 la piana di cassino-caira (piana del f. rapido), ubicazione del lago di caira, nel riguardo interno il lago come si presenta oggi. cassino-caira intermountain plain (rapido river plain); location of the caira lake; in the box the view of the lake. s. nisio & f. scapola con ingente strepito, tale che gli abitanti pensando che fosse un terremoto avevano abbandonato le case, la terra di otto tomoli, ciascuno dei quali comprende novecento cubiti napoletani di otto palmi, fu vista sprofondare a perpendicolo in quel luogo, dove c’erano alcuni alberi. la profondità di novanta palmi napoletani subito da parecchie sorgenti poste nella circonferenza dei lati iniziò ad essere riempita, mentre l’acqua cresceva così di giorno in giorno, che dopo un mese soltanto per cinque palmi distava dal piano del terreno. tutta la circonferenza del lago è di duecentosettantacinque cubiti napoletani, il diametro da oriente ad occidente circa centoventiquattro, e trasversale circa centotrentanove. oltre a questi eventi, nel giornale cassinese e negli scritti di gattola (1734), viene riportato: “la notte fra il 18 ed il 19 febbraio dello stesso anno nel luogo, ove è ora, il lago di cairo, un rumore fortissimo si intese ed i contadini che abitavano nei dintorni, come se un grande terremoto fosse accaduto, abbandonando le loro case fuggirono…… “ un'altra “fossa”, oltre al lago, si aprì alle pendici orientali di monte cairo e la tradizione afferma che in determinati periodi si sentivano dei rumori, come lamenti, provenire dalla stessa; gli abitanti del luogo iniziarono a buttare rifiuti all’interno della fenditura. dopo un po’ di tempo si accorsero che i frutti lanciati nella voragine le sere precedenti venivano ritrovati nei pressi dell’attuale chiesa madre nell’abitato di cassino. da altre fonti si ricava che il livello del lago non subiva variazioni stagionali e, periodicamente, era soggetto ad una fase di intorbidimento delle acque e le stesse venivano rese acide da uno improvviso aumento della concentrazione di zolfo. riportiamo il testo di baratta (1978): “….nacque così il lago di caira le cui acque non si vedono crescere anche nei tempi più piovosi, né diminuire. di questo lago i monaci fecero un vivaio di pesci ma periodicamente le acque si intorbidavano, probabilmente per l’afflusso di sorgenti sulfuree, ed i pesci rimanevano tramortiti. si rianimavano, però, dopo pochi giorni. la periodicità del fenomeno era tanto nota che i pescatori vi si recavano, a data fissa, per farvi buona pesca.” altre notizie del lago risalgono a de marco (1888): "il detto lago ritiene ancora la forma arrotondata; ma la circonferenza è più grande, la profondità molto minore, e la superficie è occupata da un lato quasi per un terzo da piante acquatiche a causa della terra ivi trasportata dal torrente che viene dai monti vicini. avendolo io misurato nel gennaio di quest’anno, ho trovato la sua periferia di 525 m (con un diametro medio di 165 metri circa)". si ha notizia di numerose sorgenti sulfuree (puzzaturiello, fig. 6) presenti a quell’epoca nell’area, la loro provenienza tuttavia è sempre stata imputata alla risalita, secondo vie preferenziali, di acque appartenenti alla falda profonda. e’ possibile che il progressivo svasamento del lago ed il continuo apporto di materiale detritico da parte dei torrenti abbia formato, nel tempo, un manto impermeabile al fondo impedendo l’interscambio delle acque. periodicamente i sedimenti fini potrebbero essere stati rimossi, all’aumentare della pressione della falda sottostante (questo spiegherebbe l’intorbidamento delle acque associato all’immissione di acque sulfuree nel lago). questo fenomeno lascia comunque ipotizzare la presenza di un condotto di collegamento fra la falda profonda, presente nei calcari, e le acque del lago. nel 1902 del foco scrive: "a destra di questa strada traversa, v’ha il laghetto di caira con scarse sorgenti interne. la superficie di questo lago, pel materiale importatovi da due torrenti che scendono a settentrione e a mezzogiorno del colle del forno e dei monticelli, che si riuniscono a caira, va anno per anno restringendosi, e finirà collo scomparire del tutto, con miglioramento delle condizioni sanitarie di quei dintorni infestati dalle febbri palustri. intanto quanto sarebbe desiderabile che l’autorità venisse in aiuto del lavoro lento della natura…". poco dopo il consiglio comunale decise di prosciugarlo, ma eventi naturali precedettero questo intervento di bonifica; durante una fase di piena del fiume una grande quantità di detriti si riversò nel lago (restò attivo almeno fino al 1904; fig. 6). il lago si prosciugò e, nel corso degli anni la forma si obliterò definitivamente. attualmente all’interno del vivaio della forestale sono presenti alcune sorgenti che manifestano periodiche risalite di gas. la successione stratigrafica dell’area circostante il lago (fig. 7 a, b), come rilevato da pozzi e sondaggi geoelettrici, varia procedendo da monte verso valle (da est ad ovest). nell’area di affioramento della conoide alluvionale, al di sotto di una fascia pedogenizzata (con spessore di pochi metri fino ad alcune decine), si rinvengono detriti di falda, con spessori considerevoli (cento metri circa) in contatto diretto con il substrato cabonatico. più a valle, nella zona di piana, i pozzi n.1 e n.2 (fig. 7b), molto prossimi al paleolago, mostrano la presenza di un’alternanza di argille, limi argillosi con ciottoli 231 fig. 6 mappa storica del 1902 ove è ancora riportato il lago di caira, è possibile, inoltre, individuare nelle vicinanze il toponimo puzzaturiello che fa ipotizzare presenza di gas e acque sulfuree. historic map of the 1902; it is showed the caira lake; it is possible to see close to the lake the puzzaturiello area. it demonstrate the presence of h2s acid water. ( in dialectical italian “puzzaturiello” sounds like “smelly”). individuazione di aree a rischio ... calcarei e ciottolate, il tutto al di sopra di un substrato carbonatico ubicato intorno a settanta metri di profondità dal piano campagna. questo tipo di successione stratigrafica determina valori bassi di permeabilità verticale, mentre valori elevati, negli strati a granulometria più grossolana, di permeabilità orizzontale. e’ possibile, pertanto, trovare nella copertura detritica più falde sospese ed una falda imprigionata all’interno del substrato calcareo (permeabile per fratturazione e carsismo) ribassato tettonicamente. 6.1.1 geometria iniziale della forma ed evoluzione nel tempo. ci si imbatte in molte difficoltà per determinare le dimensioni iniziali dello sprofondamento che originò il lago di caira. prima fra tutte la “discordanza” delle fonti, l’incongruenza di alcune di esse e la parzialità e/o incompletezza dei dati forniti da altre. per ricostruire la geometria iniziale della voragine bisogna partire dalle notizie storiche di g attola (1734). in queste sono presenti le seguenti indicazioni, riportate in latino e di seguito tradotte: a) sprofondati otto tomoli di terreno, ciascuno di 900 “cubiti napoletani di otto “palmi” ; b) perimetro della voragine 275 cubiti napoletani; c) asse est-ovest 124 e nord-sud 139 (dei quali l’autore non riporta però l’unità di misura). s aragosa & s aragosa (1998), tradussero il testo latino dell’autore, ed indicarono che, al momento della formazione, la cavità presentava una circonferenza di 550m e diametri di 250m e 280m. si è invece rilevato che questi dati non trovano corrispondenza tra di loro e non corrispondono alla situazione reale. volendo ricavare le dimensioni della forma in base alle antiche unità di misura si riscontrano due problemi: a) è difficile attribuire un valore preciso alle unità di misura adottate: i cubiti napoletani non vengono contemplati in nessun testo tra quelli consultati; b) nel riportare le dimensioni degli assi non è stata indicata l’unità di misura utilizzata. per accertare le reali dimensioni del lago sono state consultate fonti storiche, enciclopedie del lessico italiano e testi latini. dopo molti accertamenti si è giunti alla conclusione che le misure degli assi di (124 e 139) erano espresse in palmi e che ai palmi napoletani poteva essere attribuito il valore di 26,4 cm. applicando una formula approssimativa del perimetro dell’ellisse si riscontra che il valore dei due assi è espresso con un un’unità di misura diversa da quella del perimetro. dopo numerose ricerche concludiamo che i valori riportati nella letteratura riferiti al perimetro possono essere ricondotti ai cubiti attici e romani ai quali viene 232 fig. 7 a) schema geologico semplificato dell’area dove è avvenuto lo sprofondamento di caira; a sinistra un sondaggio geoelettrico; b) le stratigrafie dei pozzi 1 e 2. a) geological scheme, in the sinking caira area; b) electric borehole; on the right borehole (1 and 2) stratigraphy. 7a) 7b) s. nisio & f. scapola attribuito un valore di 44,4cm. individuate le unità di misura, e rimanendo fedeli alle indicazioni di gattola (1734) per quanto riguarda le proporzioni degli assi, si ricava che il lago di caira, al momento della sua formazione, aveva l’asse maggiore di 41 m, il minore di 37 m, il perimetro di 122,1m, una profondità di 23,7m (90 palmi napoletani) ed un’area di 310m2. misure effettive sulle dimensioni del lago, dopo una sua evoluzione, risalgono a de marco (1888): "avendolo io misurato nel gennaio di quest’anno, ho trovato la sua periferia di 525m (con un diametro medio di 165 metri circa)" questo significa che in 164 anni lo svasamento dei bordi con la rimozione delle particelle ha più che quadruplicato le dimensioni originarie (sulla sezione igm al 10.000 il diametro della paleoforma è di 170 m). l’interrimento del lago è successivo all’anno 1902; presumibilmente avvenne pochi anni dopo (del foco, 1902; fig. 6). 6.2 altre aree interessate da sprofondamenti la conferma della presenza dello sprofondamento di caira nell’area ha stimolato ulteriori ricerche storiche e ricognizioni in tutto il territorio per individuare altre cavità o paleoforme; difficilmente infatti un fenomeno di sinkhole s.s. si rinviene isolato. e’ stata indagata, in principio, tutta la piana di cassino, partendo dal sito in cui è stato riconosciuto il lago di caira. l’analisi delle foto aeree di tutta l’area ha messo in evidenza altre tre forme sub-circolari ormai obliterate (fig. 8), due in località vertelle (con diametri di circa 250 m) e una presso masseria chiusavecchio dove si evidenzia una paleo forma gemellata (data dalla fusione di due cavità sub-circolari) con diametro maggiore di 380 m circa. il successivo sopralluogo sul terreno presso masseria chiusavecchio ha evidenziato la presenza di un piccolo lago (fig. 8) ormai quasi estinto: la pescarola (la denominazione antica ricordata dagli abitanti, i quali affermano che si formò naturalmente), con diametro attuale di 25-30 m e scarsa profondità. alcuni abitanti affermano che il lago era già presente alla fine dell’1800 con dimensioni molto più grandi ed adibito a vivaio. negli archivi della abbazia benedettina, un atto di vendita presente nei regesti ha confermato la presenza della pescarola già nel 1676. nel 1920 tutta l’area è stata bonificata e molte polle, stagni ed eventuali cavità sono stati ricolmati. inoltre, durante il sopralluogo, è emerso che a poca distanza dalla pescarola era presente un altro laghetto, presso l’area in cui oggi sorge l’ospedale. nel corso dei lavori per la costruzione dell’ospedale si sono verificati eccessivi cedimenti del terreno (gli ultimi nell’agosto 2005) che hanno portato alla provvisoria sospensione dei lavori. il sopralluogo condotto sul terreno in località vertelle (dove si distinguevano altre forme subcircolari) non ha dato però esiti positivi in quanto l’urbanizzazione del territorio ha ormai obliterato le presunte cavità. nei pressi del lago di caira (antico mulino) è stata individuata un’altra paleoforma risalente almeno al 1200. nella porzione settentrionale della stessa piana presso s. elia fiumerapido, l’analisi fotointerpretativa ha evidenziato la presenza di altre tre paleo-forme (fig. 9), di cui due coincidono sul terreno con polle subcircolari con diametri di 8-10 m (salaluca e magnesiaca; fig 9), sedi di sorgenti di acqua mineralizzata, con abbondanti risalite di gas. le portate stimate delle sorgenti sono di 94l/sec e 68 l/sec (caramadre 1996), le conducibilità rispettivamente di 445 µσ (nel 1996) e 935 µσ, la salinità di 370 e 660 g/cm3 rispettivamente. gli alti valori di conducibilità sono compatibili con acque di provenienza profonda. presso la polla magnesiaca e’ stata eseguita la batimetria con ecoscandaglio che ha fatto registrare la presenza di una cavità tronco-conica, con pareti sub-verticali e profondità di 8 m. per quanto riguarda i dati di sottosuolo un sondaggio geognostico, reperito nelle vicinanze delle due polle, mostra la presenza di limi argillosi sino alla profondità di almeno 50m (fondo foro; fig. 9) e di due falde sovrapposte rispettivamente a 24 m e a 49 m, corrispondenti con livelli permeabili. durante il terremoto del 1984 l’acqua proveniente dalla sorgente magnesiaca ha subito intorbidimento per 3 giorni circa, con risalita di fango. i dati relativi alla polla magnesiaca sono riportati in tab. 1. in prossimità della sorgente magnesiaca era presente un’altra cavità circolare, oggi inac233 fig 8 ubicazione della pescarola; colonna stratigrafica riportante i dati di sottosuolo nelle vicinanze del laghetto e immagine di come la pescarola si presenta oggi. location of the pescarola pound; stratigraphy of the borehole data and pescarola pound view. individuazione di aree a rischio ... cessibile, contenente attualmente acqua. l’esame delle mappe storiche conferma che presso l’abitato di sant’elia, nei primi del settecento erano presenti tre laghetti uno dei quali in località acqua nera (fig 9; fig 12); le posizioni coincidono con le polle e le paleoforme individuate. la seconda area indagata è ubicata presso s. giorgio al liri (fig. 10), nella porzione meridionale del bacino lirino. nei pressi dell’abitato è ubicato il lago di acquasanta che oggi si presenta come un piccolo specchio d’acqua, con diametro di 12 m e profondità di 1,5 m, ma che, in passato, doveva avere dimensioni più grandi, infatti è presente in una mappa storica del 1700 (disegni ad acquerello di m. guglielmelli; fig. 12). il laghetto presenta emissioni di gas ed una probabile emergenza al fondo. nelle vicinanze del primo laghetto, nella piana del liri, è presente un’altra cavità sub-circolare colmata d’acqua, sede di sorgente di acqua ferruginosa risalente almeno ai primi del 1700. all’interno dell’abitato di s. giorgio al liri è ubicato un terzo laghetto ormai con sponde antropizzate e collegato al liri tramite canale artificiale, la cui origine dovrebbe risalire a più di 300 anni (è infatti riportato nelle carte antiche di gattola,1734, e di guglielmelli, 1715; fig. 10; fig. 12). il diametro della cavità è diminuito nel tempo, attualmente si attesta intorno ai 30-40 m e la profondità è pari a circa 2 m. la forma del laghetto di s. giorgio in origine era circolare; infatti l’urbanizzazione dell’area ha seguito la morfologia dell’antico perimetro del lago, e ciò testimonia che la nascita dell’abitato è successiva allo stesso (informazioni fornite dal comune di san giorgio a liri). una quarta cavità asciutta, ormai obliterata, è presente presso località s. marco: negli anni 50 il diametro si attestava intorno ai 47 m, attualmente è pari a circa 20 m; probabilmente la cavità naturale è stata successivamente sfruttata per recupero di inerti. 234 fig. 9 in alto ubicazione , presso s. elia fiumerapido, delle sorgenti e del pozzo con la relativa colonna stratigrafica; in basso, foto della sorgente magnesiaca come si presentava nel 1996 (foto di r. caramadre) e come si presenta nel 2005. at the top location of the s. elia fiumerapido springs and pounds, and borehole stratigraphy. at the bottom magnesiaca sinkhole pound photograph: in the 1996 ( left photo by caramadre) and in the 2005. fig. 10 in alto sono riportate le ubicazioni dei laghi presso s. giorgio al liri e della paleoforma asciutta nonchè del sondaggio geognostico immagini dei laghetti presso s. giorgio al liri (a sinistra) e acquasanta; a destra stratigrafie del sondaggio geognostico. at the top are represented s. giorgio al liri lakes, paleoform and borehole location. photograph of th s. giorgio lake and acquasanta lake; to the right bore hole stratigraphy. tab. 1 principiali parametri geochimici delle acque nell’area di s. elia e s. giorgio al liri. main geochemical parametres of the water samples in the s. elia s. giorgio al liri area. toponimo ph eh cond. µµ σσ t c° bicarbonati ml/l sorg. magnesiaca s. elia 6,63 164 935 13.05 732 lago di acquasanta 7,46 117 327 17 244 sorgente ferruginosa 7,4 0 370 15 317 lago di s. giorgio al liri 7,58 98 372 16 244 s. nisio & f. scapola durante il sopralluogo in sito sono state condotte analisi delle acque i cui dati vengono mostrati in tab.1. dai dati raccolti emerge che le conducibilità sono compatibili con lo scorrimento delle acque in terreni di natura alluvionale, i valori di ph potrebbero essere stati contaminati con apporti di acque superficiali e di scolo provenienti dai canali artificiali. i dati di sondaggio, nei pressi del laghetto di s. giorgio (fig. 10), mostrano una successione di limi e argille sino alla profondità di 85 m successivamente brecce calcaree e ghiaie sino alla profondità di 128 m, ed infine argille sino a foro 135 m. il substrato carbonatico, non riscontrato mai in sondaggio, pertanto, è molto profondo; si può escludere così una genesi carsica dei laghetti. nei sedimenti è stata, inoltre, riscontrata una falda in pressione alla profondità di 70 m che risale sino al piano di campagna. la terza area indagata è la piana di sora (fig. 11), a nord-ovest di cassino, in cui è stato rinvenuto un antico lago oggi ricolmato, il lago tremoletto. questo è ubicato nella tenuta dei conti manconi, secondo alcune fonti l’origine risale ad alcuni secoli addietro, in epoca borbonica; risulta comunque già presente nei primi del 1800. secondo altre fonti esso sarebbe stato originato da un episodio catastrofico, e caratterizzato dalla presenza di tremori e boati nel sottosuolo, da cui il nome “tremoletto”. a partire dal 1800 il lago ha iniziato a colmarsi per gli apporti detritici del fiume fibreno e ridotto ad un piccolo specchio d’acqua, dopo il 1948, è stato definitivamente bonificato. le stratigrafie dei sondaggi geognostici mostrano una copertura sedimentaria di sabbie e limi sino ad una profondità variabile tra i 15 m e i 25 m; al di sotto si rinvengono sabbioni calcarei e bancate di travertino di spessore complessivo di circa 20 m (fig. 11). i sondatori hanno riscontrato la presenza di vuoti alla profondità di 20-25 m. il livello di falda si attesta ad una profondità media di 40-50 m circa. ulteriore conferma della presenza di fenomeni di sprofondamento all’interno della piana di sora provengono dalla cronistoria del terremoto di avezzano, del 13 gennaio del 1915, quando si è aperta una cavità nel terreno con fuoriuscita di acqua mista a fango con formazione di vulcanelli e fontane di sabbia. dalle osservazioni finali sulle ricognizioni effettuate di paleoforme e dei laghetti rinvenuti tra la piana di cassino e s. giorgio al liri, si evince che essi si allineano secondo una direttrice orientata circa ns (n10e): la faglia theodicea; fig. 1. 7. discussione e conclusioni la situazione geologico-strutturale ed idrogeologica della bassa valle latina, ed in particolar modo delle piane di cassino e sora, è predisponente alla formazione di fenomeni di sinkhole. le piane su cui si sviluppano gli abitati sono di origine tettonica; i depositi quaternari che le colmano, con spessori di oltre cento metri, sono costituiti in prevalenza da un’alternanza di limi e argille, dotate di discreta consistenza e subordinatamente da sabbie e ghiaie; solo a luoghi, includono bancate o lenti di travertino (ad ovest del f. gari, per esempio presso la piana di sora, e i dintorni di aquino). le dorsali carbonatiche circostanti le piane sono fortemente interessate da fenomeni carsici (doline di crollo o di soluzione normale); il substrato carbonatico, al di sotto della copertura quaternaria, è profondamente disarticolato da diversi sistemi di dislocazioni ed è sede di un acquifero confinato, in cui si esplica una notevole circolazione idrica (sorgenti con portate complessive superiori ai 20 m3/s). a ciò si associa una forte circolazione sotterranea di fluidi aggressivi per la presenza di h2so4 e h2s legati al vulcanesimo di roccamonfina e/o ad una circolazione molto profonda all’interno di sistemi di faglia. l’attività antropica con emungimento indiscriminato delle acque dal sottosuolo, dal 1984 ad oggi, ha 235 fig. 11 ubicazione del lago tremoletto, presso la piana di sora (nel riquadro interno il lago come si presenta oggi) e stratigrafie dei sondaggi. ubication of tremoletto lake, in the sora plain (in the box a view of the lake now) and borehole stratigraphy. fig. 12 esempi di mappe storiche. disegni a d acquerello di guielmelli (1715), con ubicazione di alcuni laghetti. examples of historic maps: watercolors of guielmelli (1715); locations of some sinkhole ponds. individuazione di aree a rischio ... determinato l’abbassamento repentino del livello di falda e la migrazione di alcune sorgenti. l’attività tettonica recente del settore è testimoniata dalla sismicità sia storica che strumentale che ha colpito in particolare l’area di cassino dove, in occasione anche di piccole scosse strumentali, si sono verificati cedimenti del terreno di alcuni centimetri. tali caratteristiche al contorno conferiscono all’area tutte le condizioni predisponenti ed innescanti per la formazione di fenomeni di sprofondamento (sinkhole s.s.). infatti l’intera area in epoca storica era caratterizzata dalla presenza di piccoli laghetti di forma sub-circolare, (nota per questo motivo come terra dei laghi) rinvenuti su mappe antiche (ne sono stati individuati ben 23), ma oggi scomparsi o di difficile ubicazione, inoltre alcune leggende e fonti storiche narrano dell’apertura nel terreno di grandi voragini. la ricerca sul territorio ha permesso di individuare alcune morfologie sub-circolari coincidenti con piccole polle, laghetti o cavità. tra questi il lago tremoletto, nella piana di sora (di cui purtroppo si hanno pochi dati), che si è formato in seguito ad uno sprofondamento repentino del terreno in epoca borbonica non precisata; in parte interrito dagli apporti detritici del f. rapido, è stato ricolmato artificialmente dopo il 1948. la presenza però al di sotto del lago di bancate di travertino e la segnalazione da parte dei sondatori di alcuni vuoti, riscontrati durante i lavori di escavazione, possono far ipotizzare per questo lago un meccanismo di tipo diverso, probabilmente assimilabile da un covercollapse sinkhole. nella stessa piana di sora, tuttavia, le cronistorie del terremoto di avezzano nel 1915 narrano dell’apertura di una cavità con connessi episodi di liquefazione e di fuoriuscita di acque mineralizzate. più a sud, nel bacino lirino, le ricerche storiche hanno portato all’individuazione di altri laghetti di forma sub-circolare: i laghi di s. giorgio e acquasanta non riconducibili a fenomeni carsici in quanto originati al di sopra di una copertura argillosa-limosa (con spessori maggiori di 135 m) in cui è presente una falda in pressione. la conferma dei fenomeni di sinkhole è stata però accertata con lo sprofondamento di caira, noto in letteratura come lago di caira, formatosi nella notte fra il 18 ed il 19 febbraio del 1724. la raccolta di dati ha permesso di avere un quadro chiaro ed esaustivo della situazione. il lago di caira si è formato nella piana omonima, a poca distanza dall’abitato, su di una copertura costituita da un’alternanza di argille, limi argillosi con ciottoli calcarei e ghiaie con spessore di cento metri, al di sotto della quale affiora il substrato carbonatico. la falda profonda è in pressione, mentre i depositi quaternari, al tetto, contengono piccole falde sovrapposte a profondità rispettivamente di 25 m e 40 m dal p.c., in corrispondenza di lenti od orizzonti più permeabili. la voragine si è aperta in corrispondenza di un elemento tettonico di importanza regionale individuato durante i rilievi di campagna, il cui piano è visibile presso s. angelo in theodice e che attraversa tutta la piana: la faglia teodicea (con andamento circa n5-10e). all’interno della cavità vi era risalita di gas (h2s ), testimoniata dalle fonti storiche, ed a poca distanza erano ubicate sorgenti sulfuree (oggi estinte) che alimentavano il corso del fiume rapido. la morfologia della cavità risulta essere cilindrica, con pareti verticali profonde 23,5 m; è presumibile pensare che l’alimentazione del lago (il cui livello non oscillava mai) fosse dovuta all’apporto della falda più superficiale (25 m di profondità), ma non si può comunque escludere la presenza di ulteriori piccole polle di risalita di acque sulfuree (infatti periodicamente si assisteva alla morte per asfissia della fauna acquatica). in quest’area nel 1723 sono registrate nel catalogo dei terremoti molte scosse sismiche (di cui una molto intensa il 18 ottobre) ma non nella notte fra il 18 ed il 19 febbraio 1724 (anche se alcune fonti storiche narrano di un terremoto avvenuto proprio quella notte; due episodi sismici si verificarono nel settembre e nell’ottobre 1724, successivi però alla formazione del lago); pertanto non è possibile ricondurre il fattore innescante ad un evento sismico. non è noto, inoltre, se ci sia stata una brusca variazione del livello di falda attribuibile ad un evento pluviometrico importante. il processo genetico che ha originato il lago, data la profondità del substrato ed il notevole spessore dei sedimenti di copertura, nonché la loro composizione (prevalentemente limosa dotata di una certa consistenza), non può essere imputabile al lento scorrimento di particelle verso il basso (raveling) in quanto gli orizzonti argillosi-limosi impermeabili renderebbero difficile l’infiltrazione d’acqua e l’asportazione di particelle in profondità. inoltre la morfologia della cavità (così come viene descritta) cilindrica e non conica (caratteristica nei processi di raveling) fa piuttosto ipotizzare la presenza di un condotto. si esclude poi la presenza di una cavità a profondità intermedia (di circa 25-30 m) imputabile per esempio alla presenza di placche di travertino o di brecce carsificabili, in quanto non rinvenute in sondaggio. si propone pertanto un meccanismo erosivo che proceda dal basso verso l’alto collegato alla risalita di fluidi arricchiti nella componente gassosa (h2o + co2 + h2s) che avrebbero potuto sfruttare proprio la linea di debolezza, costituita dalla faglia theodicea. tale circolazione di fluidi accompagnata a processi di erosione, di sifonamento e di suffosione profonda (deep piping) dei materiali di copertura porterebbe, nel tempo, fino al collasso finale della copertura detritica. è quindi possibile che la cavità superficiale dipenda da processi agenti nel bedrock posto a notevole profondità. da quanto detto possiamo classificare lo sprofondamento che ha dato origine al lago di caira come sinkhole s.s ovvero un piping sinkhole. l’analisi fototointerpretativa su tutto il territorio ha permesso di individuare inoltre paleo-cavità e la verifica sul terreno ha confermato tali ipotesi: all’interno delle paleoforme si rinvengono laghetti in via di estinzione o piccole polle riconducibili a fenomeni del tutto simili a quello avvenuto a caira che potrebbero essersi formati nell’arco degli ultimi secoli. infatti nella piana di cassino sono presenti la maggior parte delle forme relitte sub-circolari, riconosciute: nei pressi di s. elia fiumerapido sono presenti tre forme coincidenti con antichi laghetti, in cui oggi si individua una piccola polla con sorgente (sorgente 236 s. nisio & f. scapola magnesiaca); a poca distanza da cassino sono state individuate altre paleoforme e la verifica sul terreno ha portato alla conferma della presenza di un piccolo lago, la pescarola, (presso masseria chiusavecchio) ormai quasi in estinzione. gli abitanti del luogo ricordano la presenza di un altro lago dove oggi sorge l’ospedale. a poca distanza dal lago di caira è inoltre presente una ulteriore morfologia subcircolare, delimitata da piccole scarpate, nelle cui vicinanze sorgeva un antico mulino (anno 1200), gli abitanti ricordano che anticamente era presente una sorgente e polle d’acqua stagnante. dai dati raccolti sull’intera area si può infine asserire che la piana di cassino, quella di sora e parte del territorio in pianura della provincia di frosinone sono aree ad elevata pericolosità di sinkhole, inoltre la crescente urbanizzazione del territorio e gli aumentati emungimenti di acqua dal sottosuolo ne fanno incrementare il rischio. infatti i lavori di costruzione di alcuni edifici (tra cui il nuovo ospedale) al di sopra di una paleo-forma di sprofondamento hanno subito già alcuni problemi durante l’esecuzione, ed altri ben più gravi potrebbero verificarsi in futuro soprattutto in seguito ad eventuali scosse sismiche, anche solo di tipo strumentale. pertanto il verificarsi oggi di un evento calamitoso, come quello che ha portato alla formazione del lago di caira, potrebbe certamente provocare oltre a danni gravi all’edilizia perdita di vite umane. ringraziamenti si desidera ringraziare i dott. giorgio caramanna e giancarlo ciotoli per il supporto durante i rilevamenti idrogeologici. il dott. angelo leopardi e il dott. alberto frepoli per la collaborazione alle ricerche, il dott. rossano caramadre per aver fornito alcuni dati idrogeologici. un particolare ringraziamento va a don gregorio dell’abbazia di cassino per la disponibilità durante le ricerche storiche e a don germano per il supporto durante le ricognizioni sul terreno. bibliografia accodi b. (1964) lineamenti strutturali del lazio e dell’abruzzo meridionale. mem. soc. geol. it., iv, 595-633, bologna. (1963). accordi g., carbone f., civitelli g., corda l., de rita d., esu d., funiciello r., kotsakis t., mariotti g. & sposato a.. (1988) note illustrative alla carta delle litofacies del lazio-abruzzo e delle aree limitrofe. quad. ric. scient., 144 (5), 93-168. agrillo e., bono p., casella l., d’andrea l., caramanna g. (2004) cavita’ di collasso recenti e antiche nel bacino lacustre di posta fibreno (frosinone). atti workshop “stato dell’arte sullo studio dei fenomeni di sinkholes e ruolo delle amministrazioni statali e locali nel governo del territorio roma 2021 maggio 2004”; 11-18. annunziatellis a., beaubien s.e., ciotoli g., lombardi s., nisio s. & nolasco f. 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(2004) relations among seismogenic structures, earthquakes and sinkhole phenomena: a methodological approach in the apennines (italy). 32end international geological congress. firenze 20-28 ago 2004. vol. abs, part 1, 669. frepoli a. & amato a. (2000) fault plane solution of crustal earthquakes in southern italy (1988-1995): seismotectonic implications. annali di geofisica, vol. 43, n. 3, june 2000. frezzotti m., molin d. & narcisi b. (1988) correlazione tra caratteri stutturali e sismicità storica dell’area di roccamonfina. mem. soc. geol. it., 41, 12 ff. gasparini c., iannaccone g. & scarpa r. (1985) faultplane solution and seismicity of the italian peninsula. tectonophysic, 117, 59-78. gattola e. (1733) historia abbatiae cassinensis. pars seconda, venetiis, coleti, monte cassino. gattola e. (1734) ad historiam abatiae cassinensis accessiones. venetiis, coleti, 2, 907 pp. ghisetti f. & vezzani l.(1999) depth and modes of crustal extension during the pliocene-plleistocene evolution of the apenninic belt (italy). terra nova,11, 67-71. ghisetti f., kirschner d. l., vezzani l. & agosta f. (2001) stable isotope evidence for contrasting paleofluid circulation in thrust faults and normal faults of the central apennines, italy. journal of geophysical research, 106, b5, 8811-8825. graciotti r., nisio s., & vita l. (2004) sinkholes in italy: inventury of natural phenomena and some study cases. 32end international geological congress. firenze 20-28 ago 2004. vol abs, part 1, 670. guglielmelli m. (1715) la terra di s. benedetto. nei disegni acquerellati di marcello guglielmelli (sec.xviii). vol. 4. riproduzione banca popolare cassinate. cassino 1986. i stituto n azionale di g eofisica (2000) annali di geofisica vol. 43, n. 4, 609-868. august 2000; jandolo e. (1966) la bonifica benedettina. istituto della enciclopedia italiana, fond. g. treccani. leccisotti t. & avagliano f. (1977) i regesti dell’archivio. vol. vi, abbazia di monte cassino. littlefield j.r., culbreth m.a. upchurch s.b., stewart m.t. (1984) relationship of modern sinkhole development to large scale-pholinear features. in: 238 s. nisio & f. scapola beck barry f. (1984) sinkholes: their geology, engineering & environmental impact. ed. a.a. balkema/rotterdam/boston. m attei m., f accenna c. & f uniciello r. (1994) paleomagnetic evidence for no tectonic rotation of the central italy tyrrenian margin since upper pliocene. geophysical research letters, 21, no. 6, pages 481-484. monroe w.h. (1970) a glossary of karst terminology. u. s. geol. surv. water sup. mouton j. (1973) contributo allo studio delle acque sotterranee del lazio meridionale. atti 2° conv. int. acque sott., palermo. narcisi b. (1986) ricerche di tefracronologia nella media e bassa valle latina. mem. soc. geol. it., 35, 909-912, 3 ff., 1 tab. nisio s. (2003) i fenomeni di sprofondamento: stato delle conoscenze ed alcuni esempi in italia centrale. il quaternario, 16(1), 121-132. nisio s, caramanna g., ciotoli g. (2005) sinkholes hazard in italy: first results on the inventory and analysis of some case studies. general assembly of the european geosciences union (egu), vienna april 24-29; geophysical research abs. vol. 7, 03922, 2005. nisio s., graciotti r. & vita l. (2004) i fenomeni di sinkhole in italia: terminologia, meccanismi genetici e problematiche aperte. atti workshop apat. “stato dell’arte sullo studio dei fenomeni di sinkholes e ruolo delle amministrazioni statali e locali nel governo del territorio roma 20-21 maggio 2004”, 557-572. nisio s. & salvati r. (2004) fenomeni di sprofondamento catastrofico. proposta di classificazione applicata alla casistica italiana. atti workshop apat “stato dell’arte sullo studio dei fenomeni di sinkholes e ruolo delle amministrazioni statali e locali nel governo del territorio roma 20-21 maggio 2004”, 573-584. parotto m. (1971) stratigraphy and tectonics of the eastem simbruini and westem marsica range (central apennines italy). mem. acc. naz. lincei, classe di scienze fis., mat. e nat., ser. 8, 10, roma. parotto m. (1980) apennin central. in: 26° congr. geol. inter. introduction à la géologié générale d’italie et guide à l’excursion. 112a, 33-37. p arotto m. & p raturlon a. (1975) geological summary of the central apennines. in c.n.r., structural model of italy. quad. ric. sci., 90, 257311. parotto m. & praturlon a. (1981) duecento anni di ricerche geologiche nell’italia centrale. “mem. soc. geol. it.” vol. giubilare “cento anni di geologia italiana”, 241-278. bologna pilla l. (1837) relazione dei tremuoti che afflissero la città di s. germano ed il monastero di montecassino nella primavera dell’anno, 1837. regione toscana (2002) le voragini catastrofiche, un nuovo problema per la toscana. att. conv. 31 marzo 2000, gr. s acchetti g. i. (1920) storia geologica di montecassino (stato attuale delle conoscenze e ricerche personali). stabilimento tipografico emilio di mauro, cava dei tirreni. saragosa s. & saragosa l. (1998) caira, frazione di cassino, dalle origini ad oggi. tipografia francesco ciolfi cassino. salvati, r. & sasowsky, i. d. (2002) development of cover collapse sinkholes in areas of groundwater discharge. journal of hydrology, 264. saroli m., ciotoli g., lombardi s. & mariotti g. (2004) assetto geologico e possibile sviluppo di fenomeni di sinkhole lungo la “linea val roveto-atina” atti workshop apat “stato dell’arte sullo studio dei fenomeni di sinkholes e ruolo delle amministrazioni statali e locali nel governo del territorio roma 20-21 maggio 2004”. vol abs., 66. strahler a.n. (1954) quantitative geomorphology of erosional landscapes. c.r. 19th intern. geol. cong. algiers, sect. 13, part 3, 341-354. tharp t.m. (1999) mechanism of upward propagation of cover collapse sinkhole. engineering geology, 52, 23-33. varrone m.t. (1954) marco terenzio varrone ed il cassinate. roma 1954. 239 ms. ricevuto il 6 settembre 2005 testo definitivo ricevuto il 10 novembre 2005 ms. received: september 6, 2005 final text received: november 10, 2005 individuazione di aree a rischio ... imp.bartolini la morfotettonica ed i suoi limiti come strumento d’indagine neotettonica carlo bartolini dipartimento di scienze della terra – università di firenze riassunto: bartolini c., la morfotettonica ed i suoi limiti come strumenti d’indagine neotettonica. (it issn 0394-3356, 2004). brevi riflessioni su come lo strumento morfotettonica è stato utilizzato nel nostro paese nell’arco degli ultimi trent’anni. abstract: bartolini c., morphotectonics and its limit as a tool of neotectonic investigation. (it issn 0394-3356, 2004). the author describes the way morphotectonic methods have been applied to the study of recent tectonics in italy during the last thirty years. parole chiave: morfotettonica, neotettonica. keywords: morphotectonics, neotectonics. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 251-257 1. introduzione in perfetta consonanza con l’etimo, geomorfologi e geologi strutturali hanno fatto ampio ricorso al metodo soprattutto a partire dagli anni ’60. raramente le ricerche sono state condotte da gruppi di studio ben bilanciati dal punto di vista disciplinare. per questo, alcuni oggetti di studio sono stati differentemente interpretati da ricercatori diversi e di diversa estrazione. di qui alcuni interrogativi che la disciplina suscita riguardo alla sua utilità e validità. un rapido excursus su alcuni significativi contributi pubblicati nel corso degli ultimi 40 anni in italia è il filo conduttore che può essere seguito per valutare come è evoluto l’approccio metodologico nell’ambito della comunità scientifica nazionale. 2. la fase garibaldina a parte alcuni lavori pionieristici (segre, 1950 “nastri di faglia” e biasini, 1966), la morfotettonica come metodo d’indagine è stata sostanzialmente ignorata fino alla metà degli anni ‘70. un decisivo impulso è derivato, in quegli anni, dagli studi inerenti la realizzazione della carta neotettonica d’italia del progetto finalizzato “geodinamica” del cnr. fu allora evidente, infatti, che solo l’approccio morfotettonico era in grado di fornire elementi di valutazione dell’attività tettonica recente laddove, in assenza di depositi quaternari, i tradizionali metodi propri della geologia non sono applicabili. gli studi promossi dal cnr furono in parte anticipati da analoghe indagini promosse dall’enel (1981), nelle quali gli indizi morfotettonici, spesso acriticamente presentati, ebbero un ruolo dominante. a che punto erano, in quel tempo, le conoscenze sul metodo ed i suoi limiti, anche in campo internazionale? preliminari valutazioni morfotettoniche su alcune scarpate di faglia erano state presentate da wallace (1977), anderson (1977) e da bucknam e anderson (1979). tali lavori non erano comunque noti alla maggioranza dei ricercatori impegnati, più o meno negli stessi anni, nel sottoprogetto carta neotettonica. d’altra parte, i precedenti, importanti contributi di bull (1964) e di hack (1973) relativi rispettivamente all’analisi morfotettonica dei depositi di conoide e dei gradienti fluviali erano stati pubblicati in rapporti tecnici di difficile reperibilità. per questo, gran parte dei ricercatori impegnati nel sottoprogetto carta neotettonica utilizzò inizialmente su larga scala uno strumento di indagine di cui nessuno aveva letto (perché non esisteva) il manuale d’impiego. così, in molti casi, determinate forme venivano interpretate come il possibile risultato dell’attività tettonica senza prendere seriamente in esame le cause di tipo morfoselettivo e i processi in grado di dar luogo a forme convergenti. questo approccio fu oggetto di un’approfondita disamina di bosi (1978). nettamente in anticipo sui tempi, apparve, in quegli anni, il contributo di sauro (1978) relativo alle “forme strutturali e neotettoniche nei monti lessini”. laddove erano disponibili anche dati geologici, la disparità delle interpretazioni costituì oggetto di serrati e prolungati dibattiti, non sempre risolti con soddisfazione degli interessati. per questo, nella carta neotettonica a scala 1:500.000 sono evidenti le singolari differenze nella densità degli elementi lineari in aree contermini, affidate a gruppi diversi di ricercatori che avevano considerato o meno come di interesse neotettonico gli elementi emersi in base soltanto ad evidenze morfologiche. 252 c. bartolini 3. la predilezione per le interpretazioni in chiave tettonica e sismotettonica la preferenza che dai ricercatori è stata sempre accordata in buonissima fede alle interpretazioni in chiave tettonica piuttosto che morfoselettiva o imputabile a particolari processi (si pensi al negletto ruolo della gravità) delle evidenze morfologiche, ha una motivazione abbastanza ovvia: l’accertare che una certa forma è espressiva di tettonica recente rappresenta, per il ricercatore, un risultato, mentre non lo è se la forma è riconducibile a cause diverse. citiamo, come esempio fra i tanti, le evidenze morfostrutturali segnalate da a. carton, r. iacuzzi, m. panizza & f. vaia, 1978, a proposito della faglia di nimis (fig. 1): se riconosciute come forme di erosione passiva, esse non avrebbero avuto alcun interesse ai fini della redazione della carta neotettonica. come esempio di eccessivo “peso” attribuito a possibili cause tettoniche senza un’adeguata valutazione del ruolo dei processi, possiamo riferirci al margine sud-orientale delle colline de le cerbaie, interpretato da bartolini e pranzini (1979) come scarpata di faglia (fig. 2). fig. 1 evidenze di tettonica recente lungo la faglia di nimis. tutte le forme segnalate in legenda sono interpretabili anche come forme di erosione selettiva (controllo passivo della struttura sulla morfologia). da carton, iacuzzi, panizza e vaia (1978). evidences of recent tectonic activity along the nimis fault. all features may be also interpreted as due to differential erosion (i.e. passive control exerted by the geologic structure on surface morphology). from carton iacuzzi, panizza and vaia (1978). fig. 2 a, b il margine sud-orientale delle colline de le cerbaie, interpretato da bartolini e pranzini (1979) come scarpata di faglia. in assenza di prove geologiche di un sollevamento differenziale che abbia interessato i depositi “villafranchaini” sui due lati del corso dell’arno, sarebbe stato più prudente imputare la scarpata ad erosione laterale di questo fiume e del suo affluente di destra, il pescia. the southeastern margin of le cerbaie, interpreted by bartolini and pranzini (1979) as a fault scarp. due to the lack of geological evidences of any differential uplift affecting the so called “villafranchian” deposits on the two sides of the arno river, it would have been safer to interpret the scarp as due to the lateral erosion of this river and of his tributary, the pescia river, which flow alongside the scarps. in assenza di prove geologiche di un sollevamento differenziale che abbia interessato i depositi “villafranchiani” sui due lati del corso dell’arno, sarebbe stato preferibile imputare la scarpata ad erosione laterale di questo fiume e del suo affluente di destra, il pescia, che scorrono rispettivamente a se ed est delle faglie che delimitano verso oriente le cerbaie. il ruolo morfogenetico dell’arno è stato invece riconosciuto, da parte degli stessi autori, a proposito delle faccette triangolari, scolpite in calcari, che orlano questo fiume a monte di firenze (fig. 3). dal momento che le faccette si trovano sul lato ribassato della faglia 253la morfotettonica ed i suoi limiti ... che mette a contatto i calcari alberesi, al tetto, con la formazione di sillano (fig. 4), non sarebbero forme tettoniche ma piuttosto imputabili all’erosione al piede esercitata dal fiume. presumibilmente modellate nel corso del pleistocene sup., esse hanno mantenuto una buona evidenza morfologica grazie all’elevata conservatività dei calcari della formazione di m. morello (vulgo alberese). l’interpretazione non è condivisa da boccaletti et alii (2001), che segnalano, al piede di queste faccette, una “major active fault”. la pubblicazione citata riguarda la zonazione sismica dell’area fiorentina. la tettonica recente quale indicatore di sismicità è strumento troppo attraente per non essere coltivato anche con qualche inconsapevole forzatura. come esempio di quanto la p r o s p e t t i v a s i s m o t e t t o n i c a possa condizionare l’interpretazione morfotettonica, citiamo il caso classico del m. parasano, in abruzzo. uno specchio di faglia affiora sul margine sudoccidentale. il piano appare e s p o s t o p e r e r o s i o n e d e l l a c o p e r t u r a d e t r i t i c a e n o n a seguito di una recente riattivazione della faglia. l’entità dell’esposizione varia infatti lateralmente fino ad annullarsi. serva et al. (1986), serva (1990) e blumetti et alii (1993) hanno incluso la faglia fra quelle riattivate nel corso del terremoto del fucino (1915) mentre bosi et al. (1993) ritengono che la faglia, benché attiva nel pleistocene superiore (la copertura detritica è infatti fagliata), non abbia rigiocato in occasione del terremoto. l’interpretazione in chiave morfoselettiva della faglia del m. parasano non è certo così scontata quanto può esserlo, ad esempio, quella della faglia di plakias, a creta (fig. 5 a,b), dovuta al grande divario litologico che caratterizza muro e tetto. le vistose variazioni laterali di esposizione del piano di faglia indicano che si tratta di una scarpata erosiva e non tettonica. non è comunque mai facile distinguere le cause morfoselettive da quelle tettoniche: alcune delle forme che keller (1986) nel suo notissimo schema (fig. 6) imputa ad attività recente di una faglia trascorrente possono parimenti prodursi per erosione selettiva. e’ specificamente il caso del piccolo corso d’acqua che attraversa la faglia di san andreas nella carrizo plain (fig. 7). fig. 3 faccette triangolari, scolpite in calcari, sul versante sinistro della valle dell’arno a monte di firenze. triangular facets carved in limestone on the left hand slope of the arno valley, upstream to florence. fig. 4 le evidenze geologiche fanno ritenere che le faccette si trovino sul lato ribassato della faglia (a sin. nella sezione). pertanto non sarebbero forme tettoniche ma piuttosto imputabili all’erosione al piede esercitata dal fiume. presumibilmente modellate nel corso del pleistocene sup., esse hanno mantenuto una buona evidenza morfologica grazie all’elevata conservatività dei calcari della formazione di m. morello (vulgo alberese). da bartolini e peccerillo (2002). the geological evidences show that the facets lay on the downthrown side of the fault (on the left in the geological section). therefore they appear to be originated by the lateral erosion of the river rather than being segments of a fault scarp. although apparently carved during the upper pleistocene, they maintained their shape due to highly conservatory attitude of the limestone relief. 254 4. la fase riflessiva esauriti i lavori inerenti la carta neotettonica d’italia, alcuni (solo alcuni) dei ricercatori che vi avevano contribuito si dedicarono ad approfondire le tematiche che in precedenza avevano utilizzato senza avere la possibilità materiale di effettuarne una ponderata valutazione. sono stati in particolare presi in esame, da parte di molti, i rapporti che intercorrono fra attività tettonica recente e processi erosivi e sedimentari che interagiscono con essa, consentendone un’accurata scansione temporale. fig. 5a, b scarpata di linea di faglia di plakias (isola di creta) dovuta al grande divario litologico che caratterizza muro e tetto. le vistose variazioni laterali di esposizione del piano di faglia indicano che si tratta di una scarpata erosiva e non tettonica. the plakias fault line scarp (crete) is due to the large lithologic difference between the hanging and footwall. the sizable lateral variations of the fault plane exposure point to an erosional rather than tectonic origin of the scarp. a) b) c. bartolini 255 la casistica è assai vasta e non sintetizzabile in questa sede. ci limitiamo a citare qualche esempio. ancora quando i lavori della carta neotettonica erano ancora in corso, brancaccio et al. (1979) analizzarono l’applicazione del modello di lehmann ai versanti di faglia dell’appennino meridionale, concludendo che è “molto difficile valutare la velocità di arretramento di un versante e risalire all’età della faglia che lo ha determinato sulla base di criteri esclusivamente geomorfologici”. relativamente alla cosiddetta “età della faglia”, pervenne invece a risultati incoraggianti qualche anno dopo nash (1986) che tuttavia operava in un contesto assai più favorevole: l’evoluzione erosiva delle scarpate di faglia che interessano le superfici di conoidi alluvionali. venne pubblicato alcuni anni dopo il fondamentale contributo di brancaccio et al. (1986) relativo agli “elementi morfostrutturali ereditati nel paesaggio dell’appennino centro-meridionale”, nel quale si afferma la possibilità che “elementi morfostrutturali ascrivibili al periodo della tettogenesi si trasmettano al paesaggio odierno senza subire dei modellamenti erosionali tali ”da conferir loro “una maturità che ne denunci l’età”. più recentemente, anche ascione e cinque (1995) hanno potuto accertare che gran parte delle morfostrutture associate a faglie sono dovute ad erosione selettiva. a scala di catena, invece, il condizionamento geodinamico del rilievo appenninico è stato recentemente messo in evidenza da salustri galli et al. (2001). la non coincidenza fra cime più alte e spartiacque appenninico ha trovato una convincente risposta, almeno nei suoi termini generali, 75 anni dopo che era stato evidenziato da marinelli. nel 1993 carraro ha sintetizzato la sua ventennale esperienza in materia delineando i criteri utilizzabili per evidenziare l’evoluzione recente di faglie. negli esempi presentati da questo autore, lo strumento ”morfotettonica” appare in molti casi inutilizzabile se non in stretta sinergia con valutazioni geologicostrutturali. di fatto, a partire dagli anni ’90, l’attività recente delle faglie viene principalmente valutata sulla base delle deformazioni indotte nei depositi ad esse associati. studi di dettaglio condotti su trincee in appennino meridionafig. 7 la deflessione del corso d’acqua può essere dovuta sia a cause tettoniche (il corso d’acqua subisce la trascorrenza della faglia di san andreas) che morfoselettive (utilizza la traccia della faglia per superare l’ostacolo e riprendere la direzione originaria del delusso) oppure ad una combinazione di cause. foto c. bosi. .the dextral deflection of the stream may be due to tectonics (the stream is deflected by the dextral slip of the san andreas fault), to differential erosion (the stream follows the fault line in order to be able to overcome the obstacle and then resume its former trend downhill) or to a concurrence of the two causes. fig. 6 -alcune delle forme ritenute indicative di attività recente della faglia (es.: scarpate e anomalie del reticolo) possono prodursi anche per erosione selettiva. da keller, 1986. a few features reported as indicative of recent fault activity (e.g. scarps and drainage anomalies) can be produced also by differential erosion. from keller (1986). la morfotettonica ed i suoi limiti ... 256 le hanno rivelato tassi di attività generalmente maggiori di quanto l’analisi morfologica di superficie avrebbe potuto evidenziare (es. ascione e cinque, 1997). se in alcuni casi tale discrepanza può essere imputata al diverso ambito cronologico cui i due metodi di indagine fanno riferimento, e al fatto che i ritmi dell’attività tettonica non sono costanti, più in generale il divario dovrebbe ricordarci che le evidenze morfologiche dell’attività tettonica recente sono condizionate, in misura diversa e solo parzialmente quantificabile, dall’intensità dei processi erosivi. questi dipendono da fattori climatici, che conosciamo sommariamente nelle loro caratteristiche medie ma rispetto ai quali ignoriamo la dimensione e la cadenza degli eventi estremi così importanti nella morfogenesi e da fattori litologici che crediamo di conoscere ma di cui, per lo più, ignoriamo perfino i termini del problema. prova ne siano le affermazioni del tipo “…si esclude che si tratti di erosione selettiva, dato che l’elemento morfotettonico in discussione è situato nella zona di affioramento di un’unica formazione” che non di rado compaiono sulle riviste specialistiche. 5. conclusione retrospettiva gli approfondimenti metodologici e quindi conoscitivi cui si è pervenuti in questi ultimi anni portano a ritenere che una carta neotettonica d’italia realizzata adesso avrebbe un aspetto assai diverso da quella pubblicata nel 1984 anche, ma non solo, per la maturazione di idee che ha riguardato i metodi della morfotettonica. non è il caso, però, di rinnegare il passato: è stata proprio l’esperienza scaturita da quel progetto a stimolare una maturazione di idee che è oggi in buona parte compiuta. almeno così a noi sembra. 6. prospettive vi sono alcuni metodi propri della morfotettonica che sono stati assai poco utilizzati nel nostro paese. pensiamo per esempio allo studio delle “unpaired strath terraces” in grado di fornire una prova dell’eccesso di capacità erosiva del corso d’acqua in rapporto al tasso di sollevamento regionale, che si traduce in erosione laterale (merritts et al., 1994). il riconoscimento di questo tipo di terrazzi fluviali consente anche una “salutare” riflessione sul fatto che, essendo asimmetricamente posizionati (“unpaired”) sui due lati della valle, i terrazzi fluviali non corrispondono a fasi differenziate nel tempo, come generalmente ci accontentiamo di credere, sono invece il risultato di un processo relativamente continuo di incisione ed erosione laterale (cfr. fig. 1 in santangelo, 2003). in questo ambito, la cronologia radiometrica dei terrazzi costituisce un indispensabile strumento di indagine. l’impiego degli isotopi radiogenici ha aperto, da questo punto di vista, nuove interessanti prospettive. anche lo studio dei dislivelli fra sistemi carsici ipogei e livello di base attuale (piccini et al., 2001 e piccini e drysdale, 2003) attende di essere applicato in numerosi massicci calcarei del nostro paese. lo stesso vale per la possibilità di riconoscere situazioni di sollevamento differenziale in base all’analisi dell’evoluzione del pattern idrografico (bartolini e fazzuoli, 1997, bartolini e peccerillo, 2002, figg. 6.1.4 – 6.1.7). in termini generali, i modelli di evoluzione del rilievo basati sull’integrazione di dati geodinamici, morfotettonici e morfoclimatici sono l’obiettivo più alto cui la nostra disciplina può contribuire. si tratta di avere l’umiltà e la pazienza di mettere in discussione le proprie idee con colleghi di diversa formazione, uscendo dalla autoreferenzialità che ancora caratterizza molti studi di morfotettonica. lo schema pubblicato da santangelo (2003) costituisce un esauriente ed aggiornato pro-memoria. attenzione, però. quasi tutti gli indicatori geomorfologici elencati possono avere anche una causa non tettonica, generalmente di tipo morfoselettivo. ma forse è proprio questa sua intrinseca ambiguità a rendere il metodo intrigante. lavori citati anderson t.c. (1977) compound faceted spurs and recurrent movement in the wasatch fault zone, north central utah. brigham young univ. geol. stud., 24, 83-101. ascione a. & cinque a. (1995) l’età della tettonica trascorrente nell’appennino campano: il contributo dell’analisi geomorfologica. st. geol. camerti, vol. sp., 1995/2. bartolini c. & fazzuoli m. (1997) ruolo della tettonica e della morfoselezione nell'evoluzione dell'idrografia nel bacino del f. serchio. il quaternario, 10, 415 424. bartolini c. e peccerillo a. (2002) i fattori geologici delle forme del rilievo. lezioni di geomorfologia strutturale. ii ed. pitagora editrice bologna, 216 pp. bartolini c. & pranzini g. (1979) dati preliminari sulla neotettonica dei fogli 97 (s. marcello pistoiese), 105 (lucca) e 106 (firenze). contributi preliminari alla realizzazione della carta neotettonica d'italia, pubbl. n. 251 del p.f. geodinamica, 481-523. biasini a. (1966) elementi morfotettonici, tratti da un rilievo fotogeologico, al margine dell’altipiano di ovindoli (abruzzo). geol. romana, 5, 303-312. blumetti, dramis & michetti (1993) fault-generated mountain fronts in the central apennines (central italy): geomorphological features and seismotectonic implications. earth surf. proc. landforms, 18, 203-223. boccaletti m., corti g., gasperini p., piccardi l., vannucci g. & clemente s. (2001) active tectonics and seismic zonation of the urban area of florence (italy). pure appl. geophys., 158, 23132332. bosi c. (1978) relazione introduttiva al tema “neotettonica”. mem. soc. geol. it., 19, 521-534. bosi c., galadini f. & messina p. (1993) neotectonic significance of bedrock fault scarps: case studies from the lazio-abruzzi apennines (central italy). z. geomorph. suppl.-bd. 94, 187-206. brancaccio l., cinque a. & sgrosso i. (1979) forma e genesi di alcuni versanti di faglia in rocce carbonatiche: il riscontro naturale di un modello teorico. rend. accad. sc. fis. mat. serie iv, 46, 21 pp. c. bartolini brancaccio l., cinque a. & sgrosso i. (1986) elementi morfostrutturali ereditati nel paesaggio dell’appennino centro-meridionale. mem. soc. geol. it., 35, 869-874. bucknam r.c. & anderson r.e. (1979) estimation of fault-scarp ages from a scarp-height-slope-angle relationship. geology, 7, 11-14. bull w.b. (1964) geomorphology of segmented alluvial fans in western fresno county, california. u.s. geol. survey prof. paper 352-e, 89-129. carraro f. (1993) criteri per evidenziare l’evoluzione recente di faglie. il quaternario, 6, 15-26. carton a, iacuzzi r., panizza m. & vaia f. (1978) segnalazione di una dislocazione neotettonica nel friuli fra il m. stella e il m. forchiat di reclus (attimis). mem. soc. geol. it., 19, 563-572. enel (1981) elementi di neotettonica del territorio italiano. 95 pp. hack j.t. (1973) stream-profile analysis and streamgradient index. u.s. geol. survey j. res., 1, 421429. keller e.a. (1986) investigation of active tectonics: use of surficial earth processes. active tectonics. nat. acad. press, washington, pp. 136-147. marinelli o. (1926) la maggiore discordanza tra orografia e idrografia nell'appennino. riv. geogr. it., 33, 65-74. merrits d.j., vincent k.r. & wohl e. e. (1994) long river profiles, tectonism, and eustasy: a guide to interpreting fluvial terraces. jour. geoph. res., sp. section on tectonics and topography, part ii, 99, 14031 14050. nash d.b. (1986) morphologic dating and modeling degradation of fault scarps . in: studies in geophysics active tectonics. nat. acad. press, washington, pp. 181-194 ouchi s. (1985) response of alluvial rivers to slow tectonic active movements. geol. soc. am. bull., 96, 504-515. salustri galli c., torrini a., doglioni c. & scrocca d. (2001) divide and highest mountains vs subduction in the apennines. st. geol. camerti, 1 ns, 143-153. piccini l., drysdale r., heijnis h., (2001) karst caves morphology and sediments as indicators of the uplift history in the alpi apuane (tuscany, italy). workshop "uplift and erosion", certosa di pontignano (siena), september 20 and 21, 2001. quaternary international, 101-102 (2003), 219227. piccini l., drysdale r. (2003) vincoli morfologici e cronologici per una ricostruzione dell’evoluzione del carsismo delle alpi apuane. atti 19° congr. naz. spel., bologna, 27-31 agosto 2003, sottoterra, 114, 29-34. santangelo n. (2003) interazione fra tettonica recente e processi geomorfici. il quaternario, 16, 27-34. sauro u. (1978) forme strutturali e neotettoniche nei monti lessini. gr. st. quat. padano, quad. n°4. segre a. (1950) sulla struttura dell’arco abruzzese interno. contributi di scienze geologiche, suppl. ric. scient., cnr, roma, 1-16. serva l. (1990) effetti sui suoli dei terremoti antichi e recenti nella piana del fucino. in: guidoboni e. (ed.): i terremoti prima dell’anno mille. ist. naz. geof., pp. 530-536. serva l., blumetti a.m. & michetti a.m. (1986) gli effetti sul terreno del terremoto del fucino (13 gennaio 1915); tentativo di interpretazione della evoluzione tettonica recente di alcune strutture. mem. soc. geol. it., 35, 256-263. wallace r.e. (1977) profiles and ages of young fault scarps, north-central nevada. geol. soc. am. bull., 88, 1267-1281. 257 ms. ricevutoil 1° giugno 2004 testo definitivo ricevuto l’8 novembre 2004 ms. received: june 1, 2004 final text received: november 8, 2004. la morfotettonica ed i suoi limiti ... imp. stefanelli ttaapphhoonnoommiicc eeffffeeccttss oonn tthhee ppaalleeooeeccoollooggiiccaall rreeccoorrdd ooff tthhee lloowweerr pplleeiissttoocceennee sshhaallllooww bbeenntthhiicc ffoorraammiinniiffeerraa aasssseemmbbllaaggeess ((wweesstteerrnn eemmiilliiaa,, iittaallyy)) ssiimmoonnaa sstteeffaanneellllii dipartimento di geologia e geofisica, università degli studi di bari, via orabona n° 4, 70125 bari; email: stefanelli@geo.uniba.it. abstract: stefanelli s.,taphonomic effects on the paleoecological record of the lower pleistocene shallow benthic foraminifera assemblages (western italy). (it issn 0394 – 3356, 2004). taphonomic and paleoecological quantitative analyses are drawn from benthic foraminiferal assemblages from four lower pleistocene marine sections (western emilia). then, the data are used to perform the cluster analysis (by means spps program) in order to group samples and benthic foraminifera on the basis of their taphonomic and paleoecological similarities. the sections are arranged in meter to tens-of-meters thick sedimentary cycles. the lower part of each cycle represents the sedimentological transport of shelly material from shallow sandy bottoms to slightly deeper settings (20-40m depth range) due to catastrophic flooding events. the upper part of the cycles represents the return to normal, muddy deposition in an inner shelf setting. for the taphonomic analysis, foraminifera specimens are classified into taphonomic categories on the basis of their state of preservation: (1) fresh tests, (2) opaque tests, (3) light orange to dark brown iron-stained tests, (4) black or black-striped tests filled with or replaced by pyrite (including partial dissolution of the tests), (5) breakage of the tests. in both the lithological intervals of the cycles, the high number of specimens grouped into “breakage tests” category leads to suppose the destruction of the tests as the principal taphonomic process affecting the foraminiferal assemblages. in the mudstone partings of the sandstone interval, the mechanism that caused the destruction of the tests is the transport in a shallow-high hydrodynamic setting where benthic foraminifera are put into suspension in water and collide each other and/or with sediment grains. in the same interval, paleoecological results points out that the specimens grouped into “fresh tests” category belong to displaced taxa coming from shallow sediments due to the transport. as a consequence, a correct paleoecological interpretation from the assemblages of the lower part of the cycles is not possible. in the high-bioturbated mudstones, the “breakage tests” category consists in fragments of hyaline specimens. in these lithological intervals of the cycles, the destruction of the tests may well be due to a strong dissolution activity that causes, in the typical dissolution sequence of pore-boaring species, the corrosion and amplification of the pores and, then, the destruction of the chambers. though the taphonomic activity, a paleoecological interpretation is possible. it reconstructs a sedimentary deposition in a shallow-quite environment and changes in oxygen bottom-water content. riassunto: stefanelli s., effetti tafonomici sul significato paleoecologico delle associazioni a foraminiferi bentonici di mare basso del pleistocene inferiore (emilia occidentale, italia). (it issn 0394 – 3356, 2004). due analisi quantitative, una tafonomica e una paleoecologica, sono state condotte su associazioni a foraminiferi bentonici di quattro sezioni marine. i dati ottenuti sono stati successivamente utilizzati per effettuare l’ analisi cluster (mediante programma spss) per raggruppare i campioni ed i foraminiferi sulla base delle loro analogie tafonomiche e paleoecologiche. le sezioni in esame, affioranti nella parte occidentale dell’emilia romagna, si sono depositate nel pleistocene inferiore e consistono in cicli sedimentari di alcune decine di metri di spessore. la parte inferiore di ciascun ciclo (sabbiosa) rappresenta il trasporto di materiale conchigliare proveniente da aree superficiali e depositatosi in aree profonde (20-40 metri di profondità), in seguito a piene fluviali. la parte sommitale di ciascun ciclo (argillosa) rappresenta, invece, la deposizione di sedimenti in regime marino di maggiore tranquillità. per l’analisi tafonomica, i foraminiferi sono stati raggruppati in categorie sulla base dello stato di preservazione dei gusci: 1) gusci intatti, 2) gusci opachi, 3) gusci ossidati, 4) gusci piritizzati (inclusa la parziale dissoluzione del guscio), 5) gusci rotti. in entrambi gli intervalli litologici dei cicli, la categoria “gusci rotti” raggruppa un numero alto di individui suggerendo, così, la distruzione dei gusci come il principale processo tafonomico che ha interessato le associazioni a foraminiferi. nella porzione basale dei cicli, la distruzione dei gusci è causata dal trasporto in un ambiente poco profondo e di alta energia. in un simile ambiente, i foraminiferi, portati in sospensione e urtandosi l’uno con l’altro e/o con le particelle di sedimento, si distruggono. nello stesso intervallo, l’analisi paleoecologica ha evidenziato che le specie raggruppate nella categoria “gusci intatti” appartengono a foraminiferi alloctoni, trasportati da un ambiente più superficiale a causa di eventi di trasporto. di conseguenza, per questi intervalli, una corretta interpretazione paleoecologica sulla base delle associazioni esaminate non è stata possibile. negli intervalli sommatali e bioturbati dei cicli, la categoria “gusci rotti” raggruppa frammenti di gusci di forme ialine. si ipotizza, quindi, che la distruzione dei gusci possa essere causata da un forte processo di dissoluzione. nella tipica sequenza, la dissoluzione dei gusci porosi comporta la graduale corrosione e allargamento dei pori ed, infine, la rottura delle camere. per questi intervalli l’analisi paleoecologica ha ricostruito un ambiente di deposizione tranquillo e superficiale, nel quale ci sono state variazione del contenuto di ossigeno al fondo. keywords: benthic foraminifera, early pleistocene, taphonomy, paleoecology parole chiave: :oraminiferi bentonici, pleistocene inferiore, tafonomia, paleoecologia il quaternario italian journal of quaternary sciences 1177(1), 2004, 63-74 11.. iinnttrroodduuccttiioonn benthic foraminifera represent an important tool in ecological research. a vast literature established the existence of a strong relationship between the distribution of these organisms and oceanographic properties (phleger, 1960; chierici, busi & cita, 1962; blancvernet, 1969; corliss, 1985; caralp, 1989; hermelin & shimmield, 1990; murray, 1991; barmawidjaja et al., 1992; jorissen et al., 1992). changes in their faunal 64 s. stefanelli composition are dependent on the responsiveness of each particular species, whose presence can be attributed to changes in environmental factors such as dissolved oxygen, nutrient input, water temperature and salinity, and bathymetry. hence, analyses on the composition of benthic foraminiferal assemblages provide information about the properties of the ocean bottom-waters and their variations through time. the modern-day distribution of benthic species is widely used to reconstruct the environmental conditions recorded by the fossil assemblages. murray (1991) argued that the better paleoecological interpretations are extrapolated from the “ideal dead assemblage” that reflects, with fidelity, the living assemblage. however, the dead/fossil assemblage represents many generations accumulated over a long period of time (time averaging, staff et al., 1996). furthermore, through the time, because of the relatively small size of benthic foraminifera, the dead assemblage is, potentially, very susceptible to post-mortem processes, i. e. transport and destruction of the tests, abrasion, dissolution and bioerosion (murray & alve, 1999, martin, 1999). consequently, a fossil assemblage can be relatively modified with respect to a living fauna and important information can be lost, and this may have negative implications in the paleoecological interpretation of the fossil assemblages. hence, it is important to know the manner in which the fossils are preserved, i. e. taphonomy. the type of fossil preservation can, in fact, provide important insights and contribute to a better understanding of past ecology. the present work represents a small contribution to the preservation history of the benthic foraminiferal fauna. still little, in fact, exists on the taphonomy of fossil foraminifera (murray, 1973; 1976a; 1983; douglas et al., 1980; loubere & gary, 1990; murray & alve, 1999; walker & goldstein, 1999; barbieri, 2001) and probably less is known about the rate of taphonomical alteration suffered by tests in modern settings. a quantitative taphonomical analysis is attempted on the benthic foraminiferal assemblages from four lower pleistocene marine sequences. the aim is to compare the taphonomic data with the paleoecological results and to verify to what degree the taphonomic history obliterated the paleoecological signal. moreover, since taphonomic and paleoecological results drawn from the mollusk assemblages are also available, a further purpose is to compare the response of such different tassonomic groups to taphonomic effects and paleoenvironmental changes. 22.. ggeeoollooggiiccaall aanndd ssttrraattiiggrraapphhiiccaall sseett-ttiinngg the lower pleistocene studied sequences outcrop in western emilia, along the external apennine margin and form part of the infill of the po plain-adriatic foredeep (fig. 1a). the northern adriatic is a collisional basin, characterized by active thrusting during the deposition, in which several basin-wide and unconformitybounded sedimentary cycles have been recognized (ricci lucchi et al., 1982; pieri, 1983; ricci lucchi, 1986). sedimentologic data suggest that the lower pleistocene cycles were formed by changes in clastic input, controlled by tectonics and the climate (mutti, 1996; molinari, 1997). in the early pleistocene, a phase of tectonic uplift increased the slope of the nearby mountain front and the sediment availability. simultaneously, the local climate conditions in the form of heavy rain fall triggered hyperpycnal flows and turbidite currents that caused the delivery of large amounts of sands that deposited in the shallow shelf. this hypothesis is substantiated by data from the modern mediterranean, where turbidity currents generated during river floods are recognized as important means of sediment delivery from the continent, across the shelf, and down to abyssal regions (mulder et al., 2001). conversely, during times of widespread forestal cover of the nearby mountain fronts, in meteorological conditions similar to present ones, the mud deposition prevailed (dominici, 2001). the four lower pleistocene studied sections outcrop along the flanks of the arda river (castell’arquato piacenza area) and the stirone river (salsomaggiore parma area), the enza river (s. polo – reggio area), and the tiepido river (castelnovo modena area). the sequences are arranged in meter to tens-of-meters thick sedimentary cycles (fig. 1b). the lowest part of each cycle is formed by stratified fine and coarse bioclastic sandstones intercalated with thin mudstone beds and flasers, followed upward by thoroughly bioturbated mudstones. taphonomical data (dominici, 2001) based on macrofaunal assemblages from the sandstone intervals are suggestive of the sedimentological transport of shelly material from shallow sandy bottoms (a 0-35m depth range is proposed on the basis of modern occurrences of the characterizing taxa), to slightly deeper settings (20-40m depth range), where these remains got mixed with local bivalves from dysaerobic bottoms. in this context, the upper mudstone part of each cycle represents the return to normal deposition in an inner-shelf setting. the near-monospecific assemblages dominated by arctica islandica from the sandstone intervals are interpreted as diagnostic of dysaerobic conditions. conversely, assemblages from the mudstone intervals, with a more diverse fauna dominated by venus multilamella, show normal aerobic conditions. 33.. mmaatteerriiaall aanndd mmeetthhooddss ooff aannaallyyssiiss for the benthic foraminiferal study, a total of thirtynine samples were analyzed (see again fig. 1b). the samples were collected in the mudstone beds intercalated in the sandstone intervals and in the bioturbated mudstones forming the upper part of each cycle. for each sample 300 gr. were washed over a set of sieves with mesh widths of 500, 250, 125 and 63 µm. at least 300 individuals were counted. the benthic foraminifera counted belong to the species commonly distributed in the mediterranean basin in the infralitoral zone (0-40m: sgarrella & moncharmont zei, 1993), in accordance with the paleodepth determined through macrofaunal data (dominici, 2001). in appendix a the list of the taxa encountered in this study is shown. for the taphonomic quantitative analysis, the entire washed residue > 125 µm and < 500 µm was examined in its benthic foraminifera content. the specimens were classified in the following taphonomic categories of wang & chappell (2001), slightly modified for this study. these categories are: (1) fresh tests, (2) opaque tests, (3) light orange to dark brown iron-stained tests (including partially corroded tests), (4) black or black-striped tests filled with or replaced by pyrite (including partial dissolution of the tests). to these, another two categories have been added: (5) breakage of the tests (murray & alve, 1999) and (6) pitting (boltovskoy & wright, 1976). ). finally, the percentages of frequency were calculated. for the paleoecological quantitative analysis, the fraction 125-250 µm was examined in its benthic foraminifera content and the percentages of frequency calculated. then, hierarchical cluster analysis, a statistical approach particularly indicated in presence of heteroge65taphonomic effects on ... neous data set, was performed. those taxa with a frequency of more than 2% as well as those of particular environmental significance were selected for this analysis. finally, a raw data matrix, made up of 39 samples (rows) x 19 taxa (columns), was used. hierarchical cluster analysis was performed on the relative percentage of frequencies per sample by means of spss program, version 9.0. the hierarchical clustering routine produces a dendrogram, a two-dimensional plot that shows how the data points (frequencies of taxa) can be clustered. for this work, the q-mode and r-mode clustering were performed. the q-mode clustering obtains a dendrogram that allows the recognition of samples with similar faunal compositions. in the taphonomic analysis the r-mode clustering constructs a dendrogram that allows the grouping of the fig. 1 location of the studied area and stratigraphic correlation of the small-scale sedimentary cycles detected in the four sections. localizzazione dell’area studiata e correlazione stratigrafica dei cicli sedimentari a piccola scala riconosciuti nelle quattro sezioni. 66 taphonomic categories. in the paleoecological analysis the r-mode clustering groups foraminifera with a similar ecological meaning. the most significant dendrograms were obtained using the average-linkage between group, pearson correlation. 44.. rreessuullttss 44..11 ttaapphhoonnoommiicc aannaallyyssiiss in the q-mode dendrogram, the samples are grouped into two big clusters, named cluster i and cluster ii (fig. 2). in the r-mode dendrogram, the taphonomic categories of pitting, dissolution and breakage form one cluster. the other categories are treated as poorly correlated variables and the lower degree of correlation is shown by the fresh tests. cluster i groups together samples that present the highest percentages of fresh tests, most of which come from the sandstone intervals. within this cluster, the subclusters 1a and 1c include samples with the highest values of “breakage” and “pyritization”, up to 40%. common, also, are the light orange to dark brown ironstained tests. moreover, in subcluster 1a the samples show slightly higher percentages of opaque tests. cluster ii groups, above all, samples from the mudstone intervals. within this cluster the subcluster 2a consists of samples that have a high percentage of light orange to dark brown iron-stained tests, all from the enza section. the subcluster 2b groups samples with pyritized, pitted and broken tests. finally, subcluster 2c groups together samples characterized by opaque tests. regarding the traces of oxidation and pyritization, substantial differences emerge between the tests grouped in cluster i (sandstones) and the tests grouped in cluster ii (mudstones). in the mudstones, the tests present an internal pyrite replacement evidenced by the partial dissolution and/or breakage of the shell wall. beautiful dissolution effects manifested by foraminifera are the internal moulds of hyaline perforated calcareous tests, such as valvulineria, elphidium, nonion depressulum and rosalina, and of agglutinated tests, such as textularia and dorothia. also a few individuals of quinqueloculina show internal moulds due to the partial dissolution of the test. this taphonomic feature is particularly evident in the mudstone associations of cycle 2 in arda and stirone sections. in the sandstone associations, the oxidation and/or pyritization are, generally, external. the tests assume an orange-brown and/or black staining and traces of test dissolution are rather rare. exceptions are the base of the sandstone interval of cycle 1, in the arda and enza sections, and the sandstone interval of cycle 3, in stirone section, where internal pyritized moulds of individuals of ammonia beccarii, valvulineria and quinqueloculina are also observable. focusing on the stratigraphic distribution of the different taphonomic categories, the high proportions of intact tests characterize assemblages from the mudstone partings of sandstone intervals when compared with the mudstone intervals (fig. 2). percentages of fresh tests increase eastward, reaching maximum values in samples of the tiepido section. on the contrary, the black or black-striped tests filled with or replaced by pyrite have higher percentages in the arda section, and decrease eastward. opaqueness of the tests is the dominant shell alteration in samples from the mudstone interval of cycle 1 and in basal samples of the mudstone interval of cycle 3 (the arda section). broken tests and/or fragmentation of the tests characterize the whole sedimentary cycles but show major frequencies in the mudstone intervals. a decrease in entity of this feature is observed in cycle 3 and eastward, with the exception s. stefanelli fig. 2 q-mode and r-mode clustering of the samples from the arda, stirone, enza and tiepido sections for the taphonomic analysis. raggruppamento in q-mode e r-mode dei campioni provenienti dalle sezioni arda, stirone, enza e tiepido per l’analisi tafonomica. 67 of the tiepido section. iron-stained tests are more frequent in the mudstone intervals. pitting shows its maximum effect at the base of cycle 1 in the arda area, but is rare in other cycles and in the other sections. 44..22 ppaalleeooeeccoollooggiiccaall aannaallyyssiiss the assemblages are taxonomically homogeneous in all the sections. differences concern the relative frequencies in the intervals of the sedimentary cycles. assemblages from the arda and stirone sections show the strongest affinities. similarity with the other sections, however, decreases eastward, across the enza and tiepido sections. fauna compositions are dominated by species of the genera ammonia, bulimina, elphidium, quinqueloculina, textularia, and by cassidulina carinata, with percentages up to 50%. fursenkoina schrebersiana, nonion depressulum, triloculina gibba and species of genera bolivina, rosalina, and valvulineria are subordinated, with percentages ranging from 0% to 18%. asterigerinata mamilla, bigenerina nodosaria, buccella granulata, cibicides lobutulus, dorothia gibbosa, planorbulina mediterranensis, pyrgo bulloides, reussella spinulosa, sigmoilopsis schlumbergeri and uvigerina of the “forms costate” group are rare, with percentages always lower than 3%. other taxa were scattered in the assemblages: astronion sp., cibicidoides pachydermus, globocassidulina subglobosa, globobulimina affinis, gyroidina umbonata, hanzawaia rhodiensis, hyalinea balthica, lamarkina scabra, lenticulina sp. melonis sp., nonionella turgida, sigmoilina tenuis, spiroloculina excavata, stainforthia complanata, trifarina angulosa. in fig. 3, the q-mode and r-mode dendograms are displayed. the samples arda 35 and arda 36, since they are barren in foraminifera, have been omitted. in q-mode dendrogram we distinguish the large clusters i and ii, and the small subclusters 1, 2 and 3. in r-mode dendrogram, we distinguish the large clusters a and b, and the minor subclusters c, d and e. cluster i groups samples belonging above all to the mudstone intervals. conversely, cluster ii is composed by samples belonging to sandstone intervals. subclusters within cluster i suggest a further subdivision of mudstone assemblages. subcluster 1 groups samples from cycle 2. subcluster 2 consists in tiepido samples. subcluster 3 mostly consists in samples of cycle 3. cluster a includes quinqueloculina gr. (the absolute dominating taxon in samples where it occurs), followed by t. gibba, p. mediterranensis, a. mamilla, and c. lobatulus. in cluster b, subcluster c groups together bulimina gr. and n. depressulum, subcluster d groups together c. carinata, bolivina gr. and s. schlumbergeri and subcluster e groups together textularia gr., taphonomic effects on ... fig. 3 – q-mode and r-mode clustering of the samples from the arda, stirone, enza and tiepido sections for the paleoecological analysis. raggruppamento in q-mode e r-mode dei campioni provenienti dalle sezioni arda, stirone, enza e tiepido per l’analisi paleoecologica. 68 valvulineria gr. and elphidium gr. noteworthy, ammonia gr. is a taxon common to all samples and so it is not associated to particular clusters. 55.. ddiissccuussssiioonn ooff tthhee ddaattaa 55..11 ttaapphhoonnoommyy the “fresh tests” category groups perfectly preserved intact tests (plates, figs. 1d, 3a, 5b, 7a, 8, 10, 12). the highest frequency of the “fresh tests” group is detected in the mudstone partings of the sandstone intervals of the arda, stirone and enza sections. this feature, together with the lesser traces of fragmentation, abrasion and/or dissolution, indicates that the taphonomic processes were not active or their effects were minimized in the lower part of the cycles. therefore, the taphonomic insights recorded may be suggestive of quiet paleoenvironmental settings, in which any transport at the bottom and any chemical process within the sediment involved the fauna. these taphonomic insights can also be suggestive of a different setting, strictly linked to poor oxygenated condition. the low oxygen availability may have, in fact, excluded the predatory fauna from the sediment itself thus limiting mechanical and digestive-chemical destruction. furthermore, the low oxygen availability may also have limited the ph decrease within the sediment pore waters which results from aerobic oxidation, thus limiting pore water carbonate dissolution (loubere, 1997). as a consequence, the tests are perfectly preserved. the quiet environmental scenario seems to contradict the taphonomical results drawn from mollusk fauna of the same stratigraphic intervals (dominici, 2001). the mollusk assemblages had, in fact, indicated catastrophic flooding events. focusing in detail on the shells included in the “fresh tests” category, it is observable that they belong, above all, to the order miliolida. by contrast, the fragments belong, above all, to the infaunal hyaline tests, such as those of ammonia sp., c. carinata, valvulineria sp. and elphidium sp. according to martin (1999), the nature of the tests, i. e. shell mineralogy, architecture of the microstructure and size, well controls the different states of preservation of the tests in the same shallow high-energy regime. therefore, the state of preservation of the microfauna detected in the sandstones may well be plausible with the shallow high-energy paleoenvironment. the porcelain tests of the order miliolida, having thick walls and a low number of pores, resulted to be more resistant than the hyaline tests which, on the contrary, have thin walls and a larger number of pores. different is the taphonomic signal detected in the sandstones of the tiepido section. the intact shells belong above all to the genus bulimina, which has a hyaline and thin test. by contrast, quinqueloqulina group is less frequent. this can suggest that going eastward the hydrodynamic setting changed. no transport involved the lower part of the cycle 3, thus indicating quieter scenario. the other taphonomic categories detected a group of tests coming above all from the mudstone parts of the cycles, whose original aspect is partially or totally modified. in these intervals, the great frequency of altered and broken tests and the lesser frequency of fresh tests could be suggestive of the great activity of the mechanical and chemical processes within the sediment. the alteration of the tests in light orange to dark brown color implies an iron staining process that may be from feso4 or fe(oh)2 derived from oxidation of fes2 (wang & chappell, 2001). the opacity of the tests, typical in forms whose walls were originally transparent, is indicative of the etching of calcite micro crystal edges in the tests under low ph condition (wang & chappell, 2001). pyritized tests indicate a set of chemical reactions, rather common in reduced organic muds (plates, figs. 1b, 5a, 6, 9a, b). the process of pyrizitation, often followed by partial or total dissolution of the tests, indicates strong stressed environmental conditions related, principally, to lack of oxygen (allison et al., 1995). the pitting indicates the bioerosion activity (plate 1, fig. 2), the traces of which are expressed by rounded holes (boltvskoy & wright, 1976). the broken tests and/or fragments are the effects of destruction that can be related to several causes (plates, figs. 1c, 1e, 3 c, d, 7b, 9 a, c). in a high-energy hydrodynamic regime the shell accumulation was put into suspension, the tests battered into each other and/or into the particles of the sediment and, consequently, fragmented. nevertheless, pitting is considered to be the initial phase of the dissolution of the foraminiferal carbonate by bacteria, which can lead, successively, to the disintegration of the chamber walls (freiwald, 1995). the bed preservation of the fauna in the mudstone intervals provides information about a paleoenvironment characterized by strong destructive effects. the presence of internal pyritized moulds is indicative of oxygen-poor marine environments. in low oxygenated muddy bioturbated environments, pyrite does not form in the body of the sediment but forms in anaerobic microenvironments, commonly within shells, where it forms internal moulds (martin, 1999). the absence, total or partial, of shells around the internal pyritized moulds is indicative of a dissolution process within the sediment. the total bioturbation state of the mudstone intervals of each cycle, in fact, supports the hypothesis of this process. dissolution is greatest in areas of high bioturbation since alkalinity is impeded by increased fluid through burrows and this also enhances carbonic acid production mediated by aerobic respiration (aller, 1982). dissolution effects can, therefore, well explain the high degree of fragmentation in the microfauna. the typical sequence of dissolution of pore-bearing taxa consists, in fact, in the gradual increase of corrosion and amplification of the pores and, in the end, the breakage of the chambers (martin, 1999). the relationship between the broken fraction with the dissolution process rather than hydrodynamics is well plausible with the interpretation of the mudstones as representing the return to the normal deposition after the catastrophic flooding events. unlike foraminifera, the mollusks, showing a more diverse fauna and dominated by venus multilamella, suggest normal aerobic conditions at the bottom (dominici, 2001). moreover, bivalves show no traces of pyritization: the only pyrite coatings in bivalves are detected in the sandstone assemblages. the different indications on the oxygen content given by these organisms may well be related to their s. stefanelli diverse style of life. venus multilamella lives on the seafloor, while cassidulina, bulimina, valvulineria, ammonia and elphidium live at a depth of 0.5 – 2 cm in the sediment column (murray, 1991; jorissen et al., 1995). this means that venus multilamella is influenced exclusively by dissolved oxygen content at the sea floor, unlike the infaunal foraminifera which are influenced by the oxygen concentration in sediment pore-water. thus, the coexistence of these micro and macro organisms in the same stratigraphic interval is plausible: the porewater sediment can be less oxygenated independently by the dissolved oxygen regime on the bottom-water. this is the same for the pyrite formation: it does not necessarily imply that the overlying water column was low oxygenated. certain morphologies of pyrite can be formed under broadly oxic conditions within anaerobic micro-environments (allison et al., 1995), as the presence of internal pyritized moulds of foraminifera in the oxygenated mudstones clearly confirms. still, the different effect of pyritization on the benthic organisms could be simply related to their tassonomical characteristics. in foraminifera, the pyrite formation depends on the ini69taphonomic effects on ... plate a different taphonomic aspects identified in the studied assemblages. the bar measures 0.25 mm. fig. 1 elphidium crispum. a: tests partially broken or dissolved showing the internal lining with pyrite; b: black stained test; c, e: broken shell; d: fresh test. fig. 2 tests of quinqueloculina seminulum showing the rounded holes, evident traces of pitting. a: dorsal side; b: ventral side. fig. 3 different states of preservation of tests of miliolids. a, b: fresh test of quinqueloculina seminulum and adelosina mediterranensis; c: deformed test; d: flatted test. differenti aspetti tafonomici riconosciuti nelle associazioni.studiate. la barretta misura 0.25 mm elphidium crispum. a: guscio parzialmente rotto o dissolto, con la cavità interna riempita di pirite; b: guscio nero; c, e: guscio rotto; d: guscio intatto. gusci di quinqueloculina seminulum mostranti i buchi rotondi, tracce evidenti di pitting. differenti stati di preservazione di gusci di miliolidi. a, b: gusci intatti di quinqueloculina seminulum e adelosina mediterranensis; c: guscio deformata; d: guscio schiacciato. tial shell structure and the capacity of access of iron and sulfate ions into shells (fischer, 1986), whilst only living mollusks, which get quickly buried under thick sandy beds, are not exposed to the complete degradation of the organic matter under aerobic conditions, and so, small pyrite coatings can form on the internal surfaces. the higher level of alteration shown by foraminifera, a component of the benthic community, could be explained through a longer residence in the taphonomically active zone recorded in the mudstone intervals (taz; see loubere, 1997; walker & goldstein, 1999). with this hypothesis, the mudstone intervals would represent a longer span of time with respect to muddy strata of comparable thickness from the sandstone intervals, in accordance with the general sedimentological setting (dominici, 2001). mudstones from sandstone intervals are, in fact, interpreted as produced by the waning phase of turbidity currents (dominici, 2001). 55..22 ppaalleeooeeccoollooggyy cluster a association can be considered representative of the mudstone partings of the sandstone intervals of each cycle, with the exception of the tiepido section (fig. 4). the association is formed by diverse and abundant individuals of quinqueloculina spp. and triloculina spp. scattered permanently attached forms 70 s. stefanelli plate b figg. 4, 6 black stained tests of bulimina elegans and valvulineria brayana. fig. 5 dorothia gibbosa. a: shell partially broken or dissolved showing the internal lining with pyrite; b: fresh test. fig. 7 pyrgo bulloides. a: fresh test; b: flatted test. fig. 8 fresh test of spiroloculina excavata. fig. 9 ammonia beccarii. a: broken and black stained test; b: shell partially broken or dissolved showing the internal lining with pyrite; c: fragment of test. gusci neri di bulimina elegans e valvulineria brayana. dorothia gibbosa. a: guscio parzialmente rotto o dissolto, con la cavità interna riempita di pirite; b: guscio intatto. pyrgo bulloides. a: guscio intatto; b: guscio schiacciato. guscio intatto di spiroloculina excavata. ammonia beccarii. a: guscio rotto e nero; b: guscio parzialmente rotto o dissolto, con la cavità interna riempita di pirite; c: frammento di guscio. such as c. lobatulus and p. mediterranensis and facultative mobile species such as asterigerinata sp. are also included. all these species have an epifaunal microhabitat preference commonly in well-oxygenated marine environments (murray, 1991). this fauna composition shows a strong similarity with the seagrass assemblages of the mediterranean, distributed at a depth of 2–40 m (murray, 1991). so, the restriction of the seagrass association to samples coming from sandstone intervals, interpreted as the result of the shallow water turbidity currents triggered by catastrophic flooding events, induces us to consider cluster a association as displaced, transported from shallower environments. this means that, since considered allochthonous, the taxa grouped in the association of cluster a must be subtracted from the paleoecological investigation. consequently, the fauna association is extremely poor, composed only of the taxa grouped in cluster b. the general sedimentologic aspect of the mudstone intervals and the nature of the macrofaunal association that it contains (dominici, 2001), allows, in fact, the interpretation of the fossil association of cluster b as autochthonous or parautochtonous. the scarcity of the fauna could well be related to the strongly stressed environmental condition in consequence of the high input of organic matter from the river that caused the consumption of oxygenation at the sea floor. the stressed environmental conditions, in fact, are hostile to life. in this context, the two samples barren in foraminifera, arda 35 and arda 36, both from cycle 3 of the arda section, would document an anoxic event. thus, the above-mentioned interpretation could be in good accordance with the hypothesis of hypoxic conditions at the bottom as suggested by the analysis of macrofaunal remains in life position from the sandstone interval of cycle 3 (dominici, 2001). however, the scarcity of the fauna could have been caused by the nature of the high hydrodynamic setting rather than the oxygen deficiency. the continuous impacts among the shells could have caused the destruction of a great part of the fossils. as, in fact, the taphonomic analysis indicated, the fragments belong to the delicate hyaline tests. the cluster b association can be considered diagnostic of the upper part of the cycles since it is better represented in mudstones (see always fig. 4). in the tiepido section this association characterizes also the lower part of cycle 3. within cluster b, the distribution of the associations in the subclusters c, d and e allows a further differentiation of the mudstone association from the three 71taphonomic effects on ... fig. 4 stratigraphic distribution of the associations of cluster a and cluster b throughout the sections. distribuzione stratigrafica delle associazioni dei clusters a e b lungo le sezioni. cycles (fig. 5). in the muds of cycle 1 the fauna is dominated, above all, by diverse species belonging to the genus bulimina (subcluster c association). c. carinata characterizes the muds of cycle 2 (subcluster d association). the species of the genus elphidium are abundant in the mud interval of cycle 3 (subcluster e association). ammonia gr. is abundant in samples from the enza section, particularly in sample en16 where its abundance reaches 78%, and in cycle 1 of the arda section. it decreases in the tiepido section. the taxa are common in modern muddy marine substrates from depths of 25 m downwards (murray, 1991). among them, c. carinata, valvulineria sp. bulimina gr., bolivina gr., are shallow infaunal typical of sediments that display low quantity of dissolved oxygen and rich in organic matter (murray, 1991; bergamin et al., 1992). ammonia spp. and elphidium spp. prefer well-oxygenated environments, though some species such as protelphidium granosum and ammonia beccarii var. tiepida show a moderate tolerance of lowered oxygen conditions (jorissen, 1988; murray, 1991). by schematizing the stratigraphic distribution of the subcluster associations, it is possible to reconstruct a fossil fauna replacement throughout the sedimentary cycles (fig. 6). in the upper part of cycles 1 and 2, the fossil association distribution suggests low oxygenated sediment pore-waters in shallow marine environment. in the upper part of cycle 3 the replacement by elphidium spp. and ammonia spp. seems to suggest a change in the environmental scenario, from a strictly shallow marine scenario to a lagoon one. individuals of ammonia and elphidium are, in fact, very abundant in stressed environments such as brackish lagoons and estuaries (murray, 1991). associations characterized by more than 60% of a. beccarii and a. tepida, as the frequency detected in the enza section, have been observed in the venice lagoon (albani & serandrei barbei, 1982). in the tiepido section, the replacement of bulimina spp association by the association rich in individuals of elphidium spp. and quinqueloculina spp. may well provide information about an increased dissolved oxygen content at the bottom-water surface towards the top of cycle 3. 72 s. stefanelli fig. 5 stratigraphic distribution of the associations of subcluster c, subcluster d and subcluster e, and of ammonia gr. throughout the sections. distribuzione stratigrafica delle associazioni dei subclusters c, d e e, e di ammonia gr. lungo le sezioni. 66.. ccoonncclluussiioonnss the foramoniferal taphonomic investigation represents a helpful tool in order to draw a correct paleoecological interpretation of the lower pleistocene. the investigation pointed out, in fact, that traces of paleoecological evidence had been lost over time. the destruction of the tests, the most evident post-mortem process, caused a substantial specimen loss in the fauna. part of the allochtonous or parauthocnous components has been lost. in particular, in the mudstone partings of the sandstone intervals, this loose had negative implications in the reconstruction of the paleoecological history. the fauna detected in the samples from these intervals is not able to support the reconstructed hypoxia condition at the bottom as suggested by the mollusks. the scarcity of the fauna, although typical of a hostile environment, can not be strictly related, in this case, to strong low oxygen availability. the high-energy setting induces, in fact, the hypothesis that the tests might have been totally destroyed, and, hence, no trace of their presence was detected. in the mudstone intervals, the low energy setting allowed the better preservation of the paleoecological signal. although the substantial specimen loss in the fossil association, strictly related to dissolution effects, the paleoecological results drawn from the micro fauna are well in accordance with the paleoecological results drawn from the macro fauna. aacckknnoowwlleeddggeemmeennttss thanks are due to the reviewers’ comments for the improvement of the manuscript. i wish to thank stefano dominici for the sampling of the sections and the discussions during the draft of the manuscript. financial support was provided by 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(it issn 0394-3356, 2004). il lago di mezzano é un lago di origine vulcanica presente all’interno della caldera di latera (vt). lo studio dei sedimenti e delle forme di origine lacustre, l’esecuzione di alcune trincee che hanno attraversato i terrazzi più bassi e la datazione di campioni col metodo del radiocarbonio, hanno permesso di riconoscere l’evoluzione recente del bacino idrografico del lago. in particolare é stato possibile individuare varie oscillazioni di livello e cambiamenti di forma e di estensione del lago, indicate da notevoli variazioni nella distribuzione e nella quota dei sedimenti. la presenza di sedimenti databili alla porzione media e finale dell’olocene ha permesso di ottenere informazioni più dettagliate per gli ultimi millenni. l’individuazione di opere di bonifica antiche e recenti e la correlazione cronologica con le oscillazioni di livello di altri laghi dell’italia centrale hanno permesso di stabilire che il livello del lago di mezzano veniva influenzato prevalentemente da fattori climatici, con l’eccezione degli ultimi 2000 anni, quando a tali fattori si sono aggiunti gli effetti dei tentativi di controllo del livello delle acque. abstract: giraudi c., the lago di mezzano (valentano – viterbo) level oscillations:climatic variations and human impact. (it issn 0394-3356, 2004). lago di mezzano is a lake of volcanic origin situated inside the latera caldera. the surface area is about 0.5 km2, and the catchment area is about 1 km2 with few, very small, surface inflows and one outflow. three submerged settlements of pile-dwellings and numerous metal and pottery artifacts, attributable mainly to the bronze age, have been found near the lake shore. study of the sediments and of the morphological features of lacustrine origin, the escavation of a number of trenches across the lowest terraces, and dating of samples by the radiocarbon method, have revealed the recent evolution of the lake’s drainage basin. the geological and geomorphological studies demonstrate changes in the hydrological balance and in the drainage network discharging into the lake; these data further allows the lake level variations evidenced by archaeological settlements to be framed in a clear palaeogeographic context. various late-pleistocene and holocene oscillations in level and changes in the lake’s shape and extent have been indicated by considerable variations in the distribution and depth of the sediments. the presence of sediments that can be dated from the middle and late holocene has enabled more detailed information to be obtained for the last few millennia. the identification of ancient and recent reclamation works, and chronological correlation with the oscillations in level of other lakes in central italy, have established that the level of lago di mezzano was mainly influenced by climatic factors, with the exception of the last 2000 years, when the effects of attempts to control the level of the water can be observed, in addition to said factors. before the artificial drainage, when the level was very high and the lake larger than at present (e.g. during the xv – xvii centuries), the water reached the sill level forming an outflow towards the olpeta river. at periods of high water level the catchment to lake surface ratio was 2.6 calculated from the approximate catchment size of 3.57 km2 and a lake area of about 1.36 km2. when the lake level was very low, the basin became endorheic and the streams of the northern part of the catchment reached the lake in the southernmost place, flowing through the former lake bed. parole chiave: lago di mezzano, livelli lacustri, pleistocene superiore, olocene, paleoclima, impatto antropico. keywords: lago di mezzano, lake levels, late pleistocene, holocene, palaeoclimate, human impact. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 221-230 introduzione il lago di mezzano (lazio, 42°37’n, 11°56’e, 452 m a.s.l.) é un lago vulcanico ubicato all’interno della caldera di latera (viterbo). l’interno della caldera costituisce il bacino di alimentazione del fiume olpeta ed é diviso in vari bacini secondari: alcuni di questi sono collegati da strette incisioni che hanno tagliato le soglie di antichi bacini lacustri (sadori et al., 2004). il lago di mezzano é il più recente e l’unico rimasto tra i laghi presenti all’interno della caldera: occupa il fondo di un piccolo cratere prodotto da una eruzione freatomagmatica avvenuta nel corso delle ultime fasi di attività vulcanica, circa 100.000 anni fa (nappi et al., 1995). il lago ha diametro di 800 m, profondità massima di 31 m, superficie di circa 0.5 km2, ed il suo bacino di alimentazione si estende per circa 1 km2. l’attuale dimensione del lago é però dovuta a lavori di bonifica e regimazione delle acque. prima dell’intervento antropico il bacino di alimentazione ed il lago erano molto più estesi ed era presente un emissario naturale che defluiva liberamente attraverso una soglia dando origine al fiume olpeta. l’emissario attuale (fosso delle volpi) é artificiale, ed anche i maggiori corsi d’acqua che defluivano verso il lago sono stati deviati artificialmente verso il fiume olpeta (fig. 1). le variazioni ambientali avvenute nel bacino del lago di mezzano sono state oggetto di dettagliate ricerche sedimentologiche e geochimiche da parte di vari autori (ramrath et al., 1999a; ramrath et al., 1999b; wilkes et al., 1999; ramrath et al., 2000); le ricerche condotte su carote di sedimenti prelevate sul fondo del lago non sono state corredate da adeguati studi geologici al contorno. secondo gli autori citati i sedimenti hanno registrano le principali variazioni climatiche avvenute negli ultimi 30.000 anni circa e, a partire dall’età 222 c. giraudi del bronzo, c’è stato un evidente impatto antropico. le variazioni geologiche e geomorfologiche, avvenute tra circa 4000 e 3000 anni fa, nel bacino di alimentazione del lago sono state invece prese in considerazione da sadori et al. (2004). tali autori, che si sono occupati in modo specifico dell’impatto sull’ambiente degli insediamenti dell’età del bronzo attraverso l’analisi di dati sedimentologici, pollinici ed archeologici, hanno stabilito che l’influenza antropica sull’ambiente è stata forte per lo più durante periodi di breve durata databili attorno a 3600, 3400 e 2900 anni cal b.p. molti metri sotto il livello del lago di mezzano sono presenti i resti di palafitte, attribuite a due diverse fasi dell’età del bronzo (alessio et al., 1975; petitti & mitchell, 1993; petitti, 2000; sadori et al., 2004): secondo tutte le evidenze i villaggi palafitticoli furono edificati e occupati nel corso di periodi caratterizzati da livelli lacustri molto più bassi dell’attuale. nel presente lavoro vengono evidenziati i risultati degli studi geologici e geomorfologici condotti sui terrazzi e sui sedimenti tardo-pleistocenici e olocenici presenti sia nelle aree che circondano il lago attuale che nella zona occupata dal lago prima della bonifica. attraverso lo studio delle facies e la datazione dei sedimenti è stato possibile riconoscere che il livello e l’estensione del lago di mezzano hanno subìto forti variazioni nel corso del pleistocene superiore e dell’olocene sia a causa di variazioni climatiche che di interventi antropici. fig. 1 carta geologica del bacino del lago di mezzano legenda: 1 sedimenti lacustri del quinto terrazzo; 2 sedimenti lacustri del quarto terrazzo; 3 sedimenti lacustri del terzo terrazzo; 4 materiali vulcanici; 5 accumulo di frana; 6 conoidi alluvionali; 7 orli di terrazzi lacustri; 8 trincee per impianto di irrigazione; 9 sez. 1,2,3; 10 sezione di fig. 3. geological map of the lago di mezzano basin legend: 1 5th terrace lacustrine sediments; 2 4th terrace lacustrine sediments; 3 3th terrace lacustrine sediments; 4 volcanic materials; 5 landslide deposits; 6 alluvial fan; 7 terrace scarplets; 8 trenches for irrigation pipes; 9 section 1,2,3; 10 fig. 3 section. inquadramento geologico e geomorfologico gli studi geologici e geomorfologici condotti attorno al lago di mezzano hanno evidenziato la presenza di terrazzi lacustri, sia deposizionali che erosionali, di conoidi alluvionali e di sedimenti prevalentemente lacustri che formano la piana posta a nord est del lago (fig. 1). tale piana è situata poco al di sopra del livello dell’acqua: prima dei lavori di bonifica era parte dell’alveo lacustre, come ancora indicato da una carta del 1607 riportata in romeo & urbanetti (1996). secondo sadori et al. (2004) prima delle opere di regimazione delle acque, il lago poteva subire notevoli variazioni di livello ed estensione: nel corso di periodi di bilancio idrologico positivo il lago si espandeva sulla zona pianeggiante posta a ne (fig. 2). in alcuni casi il lago raggiunse livelli così alti da superare la soglia e defluire nel fiume olpeta. in questi casi, il rapporto tra superficie del bacino di alimentazione e superficie del lago poteva essere di 2,6:1, considerando 3,57 km2 l’estensione del bacino di alimentazione e 1,36 km2 la superficie del lago. quando il livello del lago non superava la soglia, il bacino diventava endoreico. i corsi d’acqua presenti nella parte settentrionale del bacino di alimentazione raggiungevano il lago scorrendo sulla zona pianeggiante precedentemente occupata dal lago. quando il livello del lago era sensibilmente più basso dell’attuale, ad esempio nel corso dell’età del bronzo (alessio et al., 1975; petitti & mitchell, 1993; sadori et 223le oscillazioni di livello ... al., 2004) il rapporto tra estensione del bacino di alimentazione e superficie del lago poteva arrivare a 9:1, poichè la superficie del lago poteva ridursi a circa 0,4 km2 (fig. 2). l’esame morfologico mostra che il lago è circondato da una serie di lembi di terrazzi lacustri poco estesi posti a quote di circa 460, 456, 453, 451 e 450 m (figg. 1 e 3). la litologia dei depositi sui quali sono impostati i terrazzi è stata rilevata solo in corrispondenza di scavi artificiali, effettuati per la messa in opera di un impianto per l’irrigazione, in quanto l’area è completamente coperta da vegetazione erbacea. il terrazzo più elevato è impostato al tetto di una successione di limi con livelli di sabbia e ghiaia fine ed è presente, oltre che al margine del lago, anche nella zona della soglia dalla quale defluisce il fosso delle volpi; il secondo terrazzo è impostato sui prodotti vulcanici che formano il cratere ed è quindi interpretabile come un terrazzo di abrasione lacustre; è stato riconosciuto solo ai margini del lago attuale; il terzo terrazzo è impostato al tetto di una successione di sedimenti colluviali e lacustri: la base è formata da colluvi limosi con frammenti di ceramica romana non più antichi del ii secolo d.c.; su questi appoggiano sedimenti limosi pedogenizzati di origine lacustre, contenenti sparsi frammenti di mattoni e di ceramica; il terzo terrazzo è il più esteso, poiché occupa gran parte dell’area pianeggiante posta a ne del lago; fig. 2 variazioni dell’estensione del lago di mezzano nel corso di due periodi estremi e confronto con la situazione attuale. nei secoli xvi – xvii il lago raggiunse livelli molto elevati, mentre nel corso dell’età del bronzo il livelli si abbassò notevolmente. l’estensione del lago attaule è condizionato da lavori di regimazione successivi al xvii secolo. the extension of lago di mezzano size during three characteristic periods: present time, 17th centuries and bronze age. the 20th century extent of the lake was produced by reclamations works. 224 il quarto terrazzo è impostato al tetto di sabbie e ghiaie fini di ambiente lacustre litorale; oltre ad essere presente al margine del lago, esso si estende nella zona pianeggiante fin verso la soglia da cui defluisce il fosso delle volpi; il quinto terrazzo è presente al margine del lago e si estende in parte anche nella piana adiacente: è appena più elevato del livello del lago ed appare interpretabile per lo più come una forma di erosione, sui sedimenti che formano il quarto terrazzo, sviluppata dopo la regimazione del lago. la presenza di scavi artificiali ha permesso anche di rilevare, in varie zone, l’esistenza di lembi di ghiaie sabbiose, interpretabili come depositi di spiaggia, posti ad una quota di circa 454 m; tali sedimenti sono databili al periodo immediatamente pre-bonifica (vedasi oltre) ma non danno luogo ad evidenze morfologiche. la scarsità di dati disponibili ha reso necessario lo scavo di varie trincee, lunghe decine di metri, al fine di studiare i sedimenti presenti ai margini del lago, sulla piana adiacente e sulla soglia dalla quale defluisce il fosso delle volpi. l’ubicazione delle trincee è visibile in fig. 1. la sezione 1 corrisponde ad una trincea, lunga circa 60 m, scavata quasi interamente sulla superficie del quarto terrazzo, fino alla profondità di circa 5 m; essa ha mostrato una complessa successione di sedimenti lacustri separati da nette superfici di erosione. alcuni campioni ricchi di sostanze organiche sono stati datati col metodo del radiocarbonio ed è stato possibile stabilire che i sedimenti sono per la maggior parte databili alle fasi finali del pleistocene superiore e all’olocene. la serie rilevata è la seguente (dal basso verso l’alto – fig. 4). a: limi grigio verdastri con sabbia e rari ciottoletti, scavati per circa 40 cm; b: limi grigi con sabbia e ghiaia fine, potenti circa 60 cm; c: limo grigio parzialmente eteropico con i sedimenti che formano l’unità b: verso il lago diventa grigio scuro, organico, ben stratificato; la potenza massima osservata è di circa 1 m; un campione prelevato in tali sedimenti e sottoposto a datazione col metodo del radiocarbonio ha fornito un’età di 18.690±210 bp (23.040-21.380 cal bp – beta 106457); d: sabbie grossolane con ghiaia fine, di ambiente litorale, che raggiungono una potenza di circa 1,5 m e appoggiano su una chiara superficie di erosione che incide i sedimenti dell’unità c; e: limi grigi con frustoli vegetali, potenti fino a 1,5 m, con rare, sottili, intercalazioni di sabbie nella porzione intermedia ed al tetto; un campione prelevato verso la base dei sedimenti e datato col metodo del radiocarbonio ha fornito un’età di 13.090±210 bp (16.51014.410 cal bp – beta 106454); f: torba, potente fino a 1,5 m, che appoggia su una superficie di erosione incisa nei sedimenti dell’unità e; un campione prelevato alla base delle torbe e datato con il metodo del radiocarbonio ha fornito un’età di 7800±70 anni bp (8685-8400 cal bp – beta 106455); g: torba, potente al massimo 50 cm, che appoggia su una superficie di erosione incisa nei sedimenti delle unità e ed f; un campione prelevato nella parte alta della torba, datato col metodo del radiocarbonio, ha fornito un’età di 1730±60 anni bp (160-435 a.d. – beta 106456); tra la torba è stata rinvenuta la punta di un palo che, datato col metodo del radiocarbonio ha fornito un’età di 500±40 anni bp (1400-1450 a.d. – beta 128454); h: limo grigio chiaro che raggiunge la potenza di circa 30 cm; i: limo sabbioso grigio chiaro, potente circa 1 m, con intercalato un livello di sabbia e ghiaia fine di ambiente lacustre litorale; il limo giace su una superficie di erosione posteriore all’unità h; un campione prelevato nella porzione intermedia del deposito e sottoposto a datazione col metodo del radiocarbonio ha fornito un’età di 720±50 anni bp (1235-1390 a.d. – beta 106452); fig. 3 quota e litologia dei terrazzi lacustri che circondano il lago di mezzano. legenda: 1sabbia e ghiaia fine; 2limo; 3colluvio con ceramica romana; 4limo con sabbia e ghiaietto; 5substrato vulcanico. lithology and elevation of the terraces surrounding the lago di mezzano. legend: 1sand and gravel; 2silt; 3colluvium with roman pottery; 4sandy gravelly silt; 5volcanic bedrock. c. giraudi 225 f ig . 4 s e zi o n i g e o lo g ic h e 1 ,2 , e 3 . l e s e zi o n i c o rr is p o n d o n o a t ri n c e e a p p o si ta m e n te s c a va te p e r le in d a g in i g e o lo g ic h e l e g e n d a : s e zi o n i 1 e 2 = 1 s a b b ia ; 2 s a b b ia e g h ia ia f in e ; 3 li m o c o n s a b b ia e g h ia ia f in e ; 4 li m o ; 5 t o rb a s u p e ri o re ; 6 t o rb a in fe ri o re ; 7 li m o ; 8 s a b b ia e g h ia ia f in e ; 9 li m o ; 1 0 s a b b ia li m o sa ; 1 1 li m o c o n s a b b ia ; 1 2 li m o a rg ill o so ; 1 3 a rg ill a li m o sa ; 1 4 p ri n c ip a li su p e rf ic i d i e ro si o n e ; 1 5 f ra m m e n to d i p a lo . s e zi o n e 3 = 1 t e rr e n o d i ri p o rt o ; 2 s a b b ia g h ia io sa ; 3 s a b b ia ; 4 l im o c o n l e n ti d i sa b b ia g h ia io sa ; 5 s u b st ra to v u lc a n ic o ; 6 c a n a le a rt ifi c ia le . g e o lo g ic al s e c ti o n s 1 , 2 , 3 . t h e s e c ti o n s sh o w t h e s tr at ig ra p h y o f th e s e d im e n ts e xp o se d i n t h re e t re n c h e s l e g e n d : s e c ti o n s 1 a n d 2 = 1 s an d ; 2 g ra ve lly s an d ; 3 s an d y g ra ve lly s ilt ; 4 si lt ; 5 u p p e r p e at ; 6 lo w e r p e at ; 7 s ilt ; 8 s an d a n d g ra ve l; 9 s ilt ; 1 0 s ilt y sa n d ; 1 1 s an d y si lt ; 1 2 s ilt a n d c la y; 1 3 s ilt y c la y; 1 4 u n c o rf o rm it ie s; 1 5 b ro ke n w o o d e n p ile . s e c ti o n 3 = 1 so il ; 2 g ra ve lly s an d ; 3 s an d ; 4 s ilt w it h s an d y g ra ve l l e n se s; 5 v o lc an ic b e d ro c k; 6 m an m ad e c h an n e l. le oscillazioni di livello ... 226 l: sottili alternanze di sabbie ghiaiose, sabbie grossolane, sabbie limose marroni rossastre, e rare intercalazioni di limi con resti vegetali; tali sedimenti sono potenti fino a circa 1,5 m ed appoggiano su una superficie di erosione incisa nei sedimenti dell’unità i; la stratificazione è evidente nell’area prossima alla sponda lacustre ove appare inclinata sia verso il lago che verso l’esterno: probabilmente il deposito formava un cordone litorale; un campione prelevato in un livello di limi con resti vegetali ha fornito un’età radiocarbonio di 980±80 anni b.p. (895-1235 cal a.d. – beta 106453); m: sabbie fini sciolte, che formano la spiaggia attuale, ed appoggiano su una superficie di erosione che incide l’unità l. in relazione ad alcune datazioni radiocarbonio dei sedimenti, occorre sottolineare quanto segue: la data ottenuta dall’unità i appare più recente di quella relativa alla successiva unità l: tuttavia se si prende in considerazione l’incertezza si può verificare che la differenza può essere considerata minima; la presenza di un legno datato 500±40 anni bp (14001450 a.d.) nella parte sommitale delle torbe dell’unità g può sembrare una contraddizione; trattandosi però della punta di un palo, non è azzardato ipotizzare che rappresenti i resti di un palo infisso in età rinascimentale, scomparso dai sedimenti più superficiali a causa dei processi di ossidazione verificatisi dopo l’emersione. la sezione 1 è stata quella che ha fornito maggiori informazioni su stratigrafia e cronologia dei sedimenti affioranti al contorno del lago. la sezione 2 corrisponde per lo più ad una trincea, scavata parallelamente alla sponda lacustre (fig. 1), che ha interessato il quarto ed il quinto terrazzo. i sedimenti affioranti in tale sezione (fig. 4) sono del tutto analoghi ai più recenti descritti nella sezione 1. tuttavia un sondaggio, eseguito con una trivella a mano, ha indicato che nei pressi dell’emissario artificiale del lago è presente un’incisione, profonda almeno 3 metri, riempita da sedimenti argillosi-limosi, nella parte profonda, e poi limosi-argillosi, aventi litologia, colore e consistenza diversa da quelli rinvenuti nelle trincee. l’incisione indica che durante periodi di basso livello lacustre, il lago era alimentato da un corso d’acqua proveniente dalla porzione settentrionale del bacino e che tale corso d’acqua aveva inciso i sedimenti che formavano la sponda lacustre. la sezione 3 corrisponde ad una trincea, lunga complessivamente circa 80 m e profonda fino a 4 m, scavata attraverso la soglia dalla quale defluisce il fosso delle volpi e dalla quale, in caso di livello lacustre particolarmente elevato, defluiva l’emissario naturale del lago (fig. 1 e 4). la trincea ha permesso di rilevare anche la stratigrafia dei sedimenti che formano il terzo terrazzo e di raggiungere il substrato dei sedimenti lacustri, costituito da materiali vulcanici alterati. i sedimenti presenti sono (dal basso verso l’alto): limi mal stratificati grigio-giallastri con frustoli vegetali, passanti verso l’alto a limi grigio-marroni scuri pedogenizzati, con frequenti intercalazioni lenticolari di ghiaie fini in matrice sabbiosa e sabbiosa-limosa: queste corrispondono chiaramente ad alvei di piccoli corsi d’acqua incisi di 10/20 cm nei sedimenti limosi e poi colmati; sia tra i limi che tra le ghiaie sono stati ritrovati frammenti di mattoni e di ceramica; nella parte più profonda della trincea è stata individuata una incisione netta e regolare (fig. 4), profonda almeno 1,2 m e larga fino a 2,5 m, che taglia il substrato vulcanico: nella parte bassa risulta riempita da limi con sabbia grossolana e ciottoli, quindi da limi; l’aspetto dell’incisione è completamente diverso da quello degli alvei presenti tra i limi successivi e sembra essere dovuta a scavi effettuati nell’antichità; si assume quindi che vi siano stati interventi di regimazione precedenti a quelli moderni; limi sabbiosi e poi sabbie, parzialmente eteropici con i limi descritti in precedenza, che raggiungono la potenza di circa 1 m; alla base di tali sedimenti sono stati rinvenuti resti di carbone che sono stati sottoposti a datazione col metodo del radiocarbonio ed hanno indicato una età di 330±50 anni b.p. (14501665 cal a.d. – beta 106458); sabbie ghiaiose potenti fino a 1,5 m, coperte dal suolo attuale. la stratigrafia dei sedimenti messi in luce dalle trincee comprende quindi depositi lacustri databili agli ultimi 20.000 anni, ma ha evidenziato l’esistenza di importanti lacune di sedimentazione. interpretazione dei dati i dati esposti nel capitolo precedente si prestano ad interpretazioni utili per ricostruire le variazioni ambientali e le oscillazioni di livello del lago. se prendiamo in considerazione i terrazzi lacustri (4 di origine naturale e uno successivo all’intervento di regimazione) possiamo dire che, mentre i più bassi sono molto recenti, databili al ii secolo d.c. (il terzo terrazzo), al xiii-xiv secolo (il quarto terrazzo) e ad un momento successivo al xv-xvii secolo (il quinto), non vi sono dati relativi ai due terrazzi più alti. per tentare di datarli si è fatto ricorso alla correlazione con altre località. al lago di vico, un lago vulcanico posto a distanza di poche decine di chilometri, sempre in provincia di viterbo, è stata rilevata la presenza di un numero di terrazzi pari a quelli del lago di mezzano e, come nel caso in studio, l’ultimo di questi si è prodotto in seguito ad opere di regimazione antropiche (giraudi, 2000). al contrario di quel che accade per il lago di mezzano, i tre terrazzi più recenti che circondano il lago di vico sono stati inquadrati cronologicamente nell’olocene, ma i sedimenti che li formano non sono stati datati con metodi radiometrici. risultano invece datati i due terrazzi più antichi la cui età è compresa tra 28.700 anni b.p. (non calibrato) e 17.000 anni cal b.p. e tra circa 17.000 anni cal b.p. e 13.000 anni cal b.p. poichè anche ai margini del lago del fucino (giraudi, 1998), in situazioni geologiche e topografiche totalmente diverse, è stata rilevata la presenza di terrazzi di età analoga, è stato assunto (giraudi, 2000) che i terrazzi suddetti siano stati prodotti da alti livelli lacustri provocati da variazioni climatiche. in questa ottica possiamo ipotizzare che i terrazzi più elevati presenti al lago di mezzano siano databili agli stessi periodi. l’inquadramento cronologico dei terrazzi non appare smentita dai dati stratigrafici derivanti dalle trincee scavate. nella sezione 1, sedimenti lacustri fini delle unità c ed e contengono le date, rispettivamente, di 23.040-21.380 anni cal b.p. e c. giraudi 16.510-14.410 anni cal b.p. e sono ubicati all’esterno della sponda lacustre attuale; non si tratta certamente di deposti di ambiente litorale: la loro presenza sembra confermare l’esistenza di un lago più esteso dell’attuale contemporaneo alle fasi di alto livello lacustre dei laghi di vico e del fucino. si assume quindi che l’unità c sia contemporanea al modellamento del primo terrazzo e che l’unità e sia correlabile cronologicamente al secondo terrazzo. per quel che riguarda l’interpretazione generale che può essere tratta dai sedimenti messi in evidenza dalle trincee scavate (fig. 4) è possibile osservare quanto segue: le facies dei sedimenti indicano frequenti variazioni ambientali con transizioni da ambiente litorale e di spiaggia ad ambienti di lago più profondo, e quindi dimostrano il verificarsi di variazioni di livello lacustre; i sedimenti presenti nelle trincee prossime alla sponda del lago attuale sono interessati da varie lacune stratigrafiche; queste sono state prodotte dalle erosioni avvenute nel corso delle fasi di emersione provocate dalle diminuzioni di livello del lago; l’incisione profonda almeno tre metri, rappresentata nella sezione 2, deve essere contemporanea ad uno o più abbassamenti di livello, probabilmente quelli verificatisi nel corso dell’età del bronzo; i successivi aumenti di livello ne produssero poi il colmamento; oltre a sedimenti dovuti alle variazioni lacustri, vi sono sedimenti colluviali contenenti resti di ceramica romana in posizione stratigrafica e altimetrica corrispondente a quella del canale artificiale, precedente al xvxvii secolo (sezione 3 – fig.4), rilevato sotto la superficie del terzo terrazzo; per tale motivo si ritiene che siano stati attuati lavori di regimazione del lago in epoca romana; il ritrovamento di depositi di spiaggia a quote elevate databili al periodo posteriore al xv-xvii secolo conferma l’estensione del lago rappresentata nella cartografia storica: i lavori di bonifica successivi hanno modificato notevolmente la dimensione del lago e prodotto una sostanziale stabilizzazione della linea di costa. per il suo inquadramento cronologico, la superficie di erosione che separa i due livelli di torba (unità f e g fig. 4), potrebbe essere contemporanea al forte abbassamento di livello del lago verificatosi nel corso dell’età del bronzo ed essere stata parzialmente rimodellata in età romana, a causa di una diminuzione di livello prodotta dalla regimazione del lago. per quel che riguarda la datazione e la valutazione delle quote raggiunte dal livello del lago, deducibili dalle facies, dall’età e dalla quota dei sedimenti (fig. 4), è possibile notare quanto segue. in corrispondenza della sedimentazione dell’unità c, il lago modellò il primo terrazzo, l’acqua raggiunse un livello di circa 460 m e poi si abbassò notevolmente; infatti la superficie di erosione successiva raggiunge una quota di 447 m; i sedimenti di spiaggia dell’unità d si trovano fino a circa 449 m di quota, e questa può essere considerata, approssimativamente, indicativa del livello raggiunto dalle acque del lago; vi è quindi stata una risalita rispetto al minimo raggiunto al momento del modellamento della superficie di erosione compresa tra le unità c e d; in corrispondenza della sedimentazione dell’unità e il lago modellò il secondo terrazzo e l’acqua raggiunse la quota di circa 458 m, confermando la tendenza alla risalita di livello indicata già dall’unità d; successivamente il livello del lago si abbassò almeno fino alla quota di 448 m, quando si sviluppò la superficie di erosione posta a tetto dell’unità e; le torbe dell’unità f indicano un nuovo aumento di livello fino ad una quota simile o superiore all’attuale; successivamente dovette verificarsi una diminuzione di livello del lago fino a quote inferiori a 448 m, come dimostra la superficie di erosione presente al tetto dell’unità f; tale superficie di erosione deve avere avuto una evoluzione molto complessa poiché i sedimenti che la sigillano (unità g) hanno età notevolmente più recente dei depositi dell’unità f; come detto in precedenza, questa erosione è in parte contemporanea ai bassi livelli lacustri dell’età del bronzo: gli insediamenti palafitticoli, databili a due diversi periodi (le date medie calibrate dei pali datati da alessio et al. (1975) si aggirano attorno a 3400 e 2900 b.p.) si trovano fino a quote di 440-441 m; poiché gli insediamenti erano situati presso l’antica sponda lacustre si assume che le suddette quote siano, anche se non nel dettaglio, rappresentative del livello lacustre del tempo; la stessa superficie di erosione deve essersi evoluta anche al momento della regimazione romana del lago; le torbe dell’unità g indicano un ritorno dell’acqua lacustre a quote superiori alle attuali in un periodo successivo alla regimazione del lago di età romana; i sedimenti dell’unità i indicano una continuazione della tendenza alla risalita di livello del lago fino ad una quota superiore all’attuale, anche se tra i sedimenti limosi vi è una intercalazione di depositi litoranei che indicano una riduzione del livello del lago; la superficie di erosione posta al tetto di tale unità indica poi un nuovo abbassamento di livello lacustre fino a quote inferiori a 449 m; in corrispondenza dell’unità l il livello del lago torna a crescere fino ad una quota prossima o superiore a 451 m; l’aumento di livello del lago continua poi fino alla deposizione dei sedimenti di spiaggia posti a circa 454 m, che rappresentano gli ultimi depositi precedenti alle opere di regimazione moderna. i dati relativi alle età ed alle quote raggiunte dall’acqua del lago nei vari periodi sono rappresentati in fig. 5. discussione anche se la successione sedimentaria presenta molte lacune, l’interpretazione dei dati ha permesso di riconoscere variazioni di livello e di estensione del lago. tali variazioni devono, evidentemente, essere legate a cambiamenti avvenuti nel bacino di alimentazione del lago di mezzano, provocate da fattori naturali o da cause antropiche. la bonifica posteriore al xvii secolo ha ridotto notevolmente l’estensione ed il livello del lago rendendo disponibile per l’agricoltura circa 1 km2 di terreno pianeggiate, precedentemente occupata dalle acque. la 227le oscillazioni di livello ... stessa zona emerse anche in epoca romana quando i lavori di regimazione provocarono la diminuzione di livello dell’acqua. nel corso dell’età del bronzo i villaggi palafitticoli presenti sulla sponda del lago produssero certamente un impatto sull’ambiente, come dimostrato da sadori et al. (2004). la durata dell’impatto antropico è stata però limitata al periodo di presenza degli insediamenti palafitticoli. tuttavia gli insediamenti si svilupparono quando il livello del lago era già sceso a quote molto basse e vennero poi sommersi dalla risalita delle acque. per questo motivo si ritiene che l’attività antropica dell’età del bronzo non sia stata la causa principale delle oscillazioni di livello del lago. le altre oscillazioni registrate dai sedimenti sarebbero invece da attribuire a variazioni del bilancio idrologico indotte dal clima. in fig. 5 sono messe a confronto le variazioni di livello del lago di mezzano e quelle dei laghi fucino e vico: si può osservare che, nonostante le lacune di sedimentazione, le oscillazioni del lago di mezzano tra circa 22.000 e 14000 anni fa possono essere correlate, in generale, con quelle del lago di vico riportate da giraudi (2000). inoltre, le variazioni lacustri avvenute tra circa 10.000 e 4000 anni fa, sono paragonabili, in generale, a quelle del lago fucino riportate in giraudi 228 fig. 5 oscillazioni di livello del lago di mezzano e correlazioni con le variazioni di livello del lago di vico e del fucino. legenda: 1 datazioni radiometriche; 2 livello del lago inferiore alla quota segnalata; 3 livello del lago superiore alla quota segnalata; 4 periodi di bassi livelli lacustri; 5 oscillazioni di livello dovute ad intervento antropico. lake level variations of the lago di mezzano and comparison with the water level oscillations in the vico and fucino lakes. legend: 1 radiocarbon ages; 2 lake level lower that the elevation evidenced; 3 lake level higher than the elevation evidenced; 4 periods of low lake level; 5 lake level oscillations produced by human impact. c. giraudi (1998), basate su un numero molto maggiore di dati. per gli ultimi 4000 anni, avendo a disposizioni più dati, è possibile verificare che le variazioni di livello nei laghi di mezzano e fucino sono pressoché coeve (fig. 5) ed escludere, per le variazioni di livello dell’età del bronzo una causa antropica. infatti, le due forti oscillazioni negative registrate a mezzano attorno circa 3400 e 2900 anni b.p. sono presenti anche al fucino, un lago molto più esteso ed il cui bilancio non poteva essere facilmente influenzato dalle popolazioni preistoriche e protostoriche. in entrambe i laghi sono state eseguite opere di regimazione o bonifica nel corso del periodo romano e in epoca moderna. i forti aumenti di livello raggiunti nelle fasi finali del pleistocene superiore ai laghi di mezzano, fucino e vico, corrispondono a fluttuazioni climatiche avvenute nel corso dell’ultimo massimo glaciale e indicate anche dalle fasi glaciali dell’appennino (giraudi, 1998; giraudi, 2004). secondo ramrath et al. (1999a) l’inizio del tardiglaciale e mezzano è datato circa 14.500 anni cal b.p.: proprio attorno a tale data ha inizio anche la diminuzione di livello lacustre. la fortissima diminuzione di livello databile a poco meno di 4000 anni b.p. coincide con il crollo della concentrazione del polline presente nelle carote studiate da sadori et al. (2004). l’aumento di livello di età compresa tra circa 2900 anni b.p. e l’intervento di regimazione romano sembra correlabile cronologicamente ad un evento registrato nell’appennino: la fase di avanzata del ghiacciaio del calderone che ha provocato la copertura di un suolo datato attorno a 2800 anni cal b.p. (giraudi, 2002; 2004). inoltre gli aumenti di livelli del periodo precedente all’anno 1000 e del xv-xvii secolo possono essere correlati cronologicamente a fasi di avanzata del ghiacciaio del calderone datati al periodo compreso tra vii e x secolo ed alle fasi iniziali della piccola età glaciale (xv-xvi secolo). conclusione lo studio dei sedimenti lacustri e dei terrazzi presenti ai margini del lago di mezzano ha permesso di verificare che nelle fasi finali del pleistocene superiore e nell’olocene si sono verificate numerose variazioni di livello dell’acqua. la maggior parte di tali oscillazioni sembra dovuta a variazioni climatiche che hanno modificato il bilancio idrologico del bacino di alimentazione del lago. vi è una buona correlazione tra le oscillazioni dei laghi di mezzano, vico e fucino ed alcuni eventi climatici registrati in italia centrale, comprese le aree sommitali dell’appennino. durante l’olocene gli aumenti di livello delle acque sono contemporanei a fasi di avanzata neoglaciali del ghiacciaio del calderone, quindi a periodi di clima più fresco e umido. sono altresì evidenti le conseguenze di due interventi antropici: il primo databile all’età romana, il secondo effettuato in epoca successiva al xvii secolo. in entrambe i casi il livello del lago e le dimensioni del suo bacino di alimentazione sono stati fortemente ridotti per recuperare all’agricoltura una vasta zona di terreno pianeggiante in precedenza coperto dall’acqua. ringraziamenti le ricerche sul lago di mezzano sono state condotte in collaborazione con la soprintendenza archeologica per l’etruria meridionale, in particolare con la dott. p. petitti. si ringrazia il dott. e. cerilli per la collaborazione prestata durante parte delle ricerche di campagna. le ricerche sono state condotte con il supporto finanziario del ministero per l’ambiente nell’ambito di un accordo di programma enea – ministero per l’ambiente, progetto 2.4 – variazioni climatiche. riferimenti bibliografici alessio m., bella f., improta s., belluomini g., calderoni g., cortesi c., manelli g.l., vigilante, a. (1975) university of rome carbon 14 dates xiii. radiocarbon 17, 313-327. giraudi c. (2000) le oscillazioni di livello del lago di vico (lazio) nell'ambito delle variazioni climaticoambientali dell'italia centrale. il quaternario, 13 (1/2),21-30. giraudi c. (1998) late pleistocene and holocene lake level variations in fucino lake (abruzzo central italy) inferred from geological, archaeological and historical data. esf workshop "palaeohydrology as reflected in lake-level changes as climatic evidence for holocene times". palaoklimaforschung, 25, 1-17. gustav fisher verlag ed. giraudi c. (2002) le oscillazioni del ghiacciaio del calderone (gran sasso d’italia, abruzzo italia centrale) e le variazioni climatiche degli ultimi 3000 anni. il quaternario, 15 (2), 145-150. giraudi c. (2004) the apennine glaciations in italy. in: ehlers,j., gibbard, p.l. (eds.), quaternary glaciations-extent and chronology, part. i: europe. 215-224. amsterdam. elsevier. nappi g., renzulli a., santi p., gillot p.y. (1995) geological evolution and geochronology of the vulsini volcanic district (central italy). bollettino società geologica italiana 114, 599-613. petitti p. (2000) la caldera di latera: appunti su materiali di nuova scoperta e contatti a lunga distanza. in: negroni catacchio, n. (ed.), preistoria e protostoria in etruria. atti del iv incontro di studi. milano, 141-149. petitti p., mitchell e. (1993) dati preliminari sulla topografia dell’abitato sommerso del lago di mezzano. in: vulcano a mezzano, 17-31. comune di valentano-museo civico. ramrath a., nowaczyk n.r., negendank j.f.w. (1999a) sedimentological evidence for environmental changes since 34,000 years bp from lago di mezzano, central italy. journal of paleolimnology 21, 423-435. ramrath a., zolitschka b., wulf s., negendank j.f.w. (1999b) late pleistocene climatic variations as recorded in two italian maar lakes (lago di mezzano, lago grande di monticchio). quaternary science reviews 18 (7), 977-992. ramrath a., sadori l., negendank j.f.w. (2000) sediments from lago di mezzano, central italy: a 229le oscillazioni di livello ... record of late glacial/holocene climatic variations and anthropogenic impact. the holocene 10 (1), 87-95. romeo l., urbanetti p.e. (1996) la rappresentazione del territorio di vulci e montalto di castro. mostra cartografica, bibliografica, documentaria . catalogo. ed. cooperativa archeologica. 82 pp. arti grafiche giorgi & gambi, firenze. sadori l., giraudi c., petitti p., ramrath a. (2004) human impact at lago di mezzano (central italy) during the bronze age: a multidisciplinary approach. quaternary international,113/1,5-17. wilkes h., ramrath a., negendank j.f.w. (1999) compositional variations of sedimentary organic matter as indicators of environmental changes since 34.000 years bp at lago di mezzano, central italy. journal of paleolimnology 22, 349–365. 230 ms. ricevuto l’11 maggio 2004 testo definitivo ricevuto il 22 giugno 2004 ms. received: may 11, 2004 final text received: june 22, 2004. c. giraudi imp.munno-petrosino nneeww ccoonnssttrraaiinnttss oonn tthhee ooccccuurrrreennccee ooff yy--33 uuppppeerr pplleeiissttoocceennee tteepphhrraa mmaarrkkeerr llaayyeerr iinn tthhee ttyyrrrrhheenniiaann sseeaa rroossaallbbaa mmuunnnnoo11 && ppaaoollaa ppeettrroossiinnoo11 1dipartimento di scienze della terra dell'università di napoli federico ii l.go s. marcellino 10, 80138 napoli abstract: munno r. & petrosino p., new constraints on the occurrence of y-3 upper pleistocene tephra layer in the tyrrhenian sea. (it issn 0394 – 3356, 2004). a widespread tephra layer, other than the well known y-5, has been identified in the upper pleistocene marine succession in the tyrrhenian sea. two investigated gravity cores showed, in fact, the presence of two companion pyroclastic tephra layers, separated by a varying thickness of pelagic sediments. the pyroclastic layers are mainly made up of pumice fragments and glass shards together with few k-feldspars and clino-pyroxene crystals. both layers are alcali-trachytic in composition, even though a sharp difference emerges in the k/na ratio that characterizes the two glasses. 14c dating of foraminiferous shells embedded in the clay layers directly underlying the most recent tephra gave an age of about 26 ka. an accurate review of literature regarding tephrostratigraphy in the mediterranean area made it possible to correlate the older one to the y-5 marker layer, joined to the campanian ignimbrite eruption, a paroxystic event in the campi flegrei area. the younger layer has been correlated with the y-3 marker layer and probably represents another huge pyroclastic flow event from the campanian area, whose products have not yet been distinguished in the field from those of typical campanian ignimbrite. this work clearly identifies the layer y-3, firstly recorded by keller et al. (1978), as the result of a specific volcanic event different from the campanian ignimbrite (marker layer y-5), defines its mineralogical and chemical composition together with its relative age offering an useful support for paleoclimatic and paleoenvinromental reconstruction of the sedimentation in the tyrrhenian area. riassunto: munno r. & petrosino p., caratterizzazione di y-3, un tefra per il pleistocene superiore nel mar tirreno. (it issn 0394 – 3356, 2004). nella successione marina del pleistocene superiore, nel basso tirreno, è stato identificato e caratterizzato un livello di tefra diverso dall'y-5, che è il livello marker in genere associato con la grossa eruzione dell' ignimbrite campana. molti gravity cores analizzati hanno infatti mostrato la presenza di una doppietta di livelli piroclastici, separati da uno spessore variabile di sedimenti pelagici. i livelli di tefra sono entrambi costituiti da frammenti di pomici e shard vetrose con una minima percentuale di cristalli di k-feldspato e clinopirosseno. entrambi i livelli mostrano un chimismo alcalitrachitico, ma sono caratterizzati da una netta differenza nel rapporto k/na. datazioni 14c ottenute su gusci di foraminiferi prelevati all'interno dell'argilla alla base del tefra più recente hanno fornito un'età di circa 26 ka. una revisione accurata della letteratura riguardante la tefrostratigrafia nell'area mediterranea ha permesso di correlare il più antico con il marker y-5, che rimanda all'eruzione dell'ignimbrite campana, un evento parossistico proveniente dall'area flegrea. il livello più recente è stato correlato con il marker y-3 e, probabilmente, rappresenta un altro evento di rilievo dell'area campana, i cui prodotti, sul campo, non sono stati ancora distinti da quelli dell'ignimbrite campana. il lavoro identifica in maniera definitiva il livello y-3, individuato per la prima volta da keller et al. (1978), come il risultato di un evento specifico diverso dall'ignimbrite campana (marker layer y-5), ne definisce la composizione mineralogica e chimica, l'età relativa e, mappandone la distribuzione, offre un utile supporto per la ricostruzione paleoclimatica e paleoambientale della sedimentazione nell'area mediterranea. keywords: gravity core, tephra layer, tephrocronology, campanian ignimbrite parole chiave: carote, livello di tefra, tefrocronologia, ignimbrite campana il quaternario italian journal of quaternary sciences 1177(1), 2004, 11-20 11.. iinnttrroodduuccttiioonn during the last 40000 years several violent volcanic eruptions took place in the campanian volcanic province, southern italy. in particular, the main volcanic sources in the area for that time-span are campi flegrei and somma-vesuvio. although a good knowledge of their activity is now available, and the products are quite well mapped in areas proximal to the sources, some difficulty however persists in the identification of the origin of tephra layers when they are found interbedded to sedimentary sequences in areas many kilometres far from the volcanoes. this is the particular field of interest of tephrostratigraphy and tephrochronology that, together with a detailed biostratigraphy, make it possible to identify marker horizons useful for geological and geomorphological reconstructions. starting from about 40 ka b.p. the best represented campanian tephra layer in the central mediterranean is y-5, so labelled according to the nomenclature of tephra layers in the eastern mediterranean of keller et al. (1978). although a great deal of testified occurrences of this pyroclastic layer are available, no clear attribution to a source has been made until recent. firstly, keller et al. (1978), in fact, attributed it to the ischia citara-serrara fontana formation, even if this formation, which is the product of several small-volume eruptions, is not widely dispersed in the field (vezzoli, 1988). shortly following this attribution, thunnel et al. (1979) definitely correlated the y-5 tephra layer with the campanian ignimbrite, recorded in the field as a widespread pyroclastic flow deposit (barberi et al., 1978; fisher et al., 1993; rosi et al., 1996) joined to a thick pyroclastic fall layer emplaced 12 r. munno & p. petrosino towards the east from the campi flegrei source area (rosi et al., 1999). most of the recent tephrostratigraphic studies agree with a campanian ignimbrite origin for the y-5 layer; only paterne et al. (1986, 1988), in fact, still ascribe the tephra to the citara-serrara fontana formation of the ischia island. actually, the attribution of y-5 to the campanian ignimbrite rises also some chronological problems. the deposit has been dated by single crystal high precision 40ar/39ar method to 37.1±0.4 ka b.p. (deino et al., 1992,1994), but new 40ar/39ar geochronology defines the age of the campanian ignimbrite at 39.28±0.11 ka, about 2000 years older than the previous estimate (de vivo et al., 2002). a great deal of 14c dates on paleosols and charbonized wood, available in literature (alessio et al., 1971; 1973; 1974), however, gave an age scattering between 25 and 40 ka b.p. two k/ar dates (curtiss, 1966; cassignol and gillot, 1982) gave an age of 30 and 34.5 b.p. ka, respectively. according to this data some authors believe that the campanian ignimbrite must not be considered as a single eruptive episode, entailing the emplacement of a single pyroclastic flow deposit, but as the result of a series of eruptive episodes, separated by significant temporal hiatuses (scandone et al., 1991; calderoni et al., 1993), that brought to the emplacement of the ignimbrite deposit observed in campania. more recently, de vivo et al., 2002, identify on the campanian plain volcanic events other than the campanian ignimbrite, displaying similar field features. the hypothesis of the existence of more than a single volcanic event representing the campanian ignimbrite l.s. is supported by the occurrence, in the tephrostratigraphical record of the central mediterranean area, of more than one ash layer in the 25-40 ka time-span, attributed by paterne et al. (1988) to a "campanian ignimbrite series". a second campanian tephra layer has never been recorded along the tyrrhenian coast, but only detected in some deep sea cores in the ionian sea. the layer, named y-3, displays an extrapolated age of about 25 ka b.p. (narcisi & vezzoli, 1999), is trachytic in composition and has generically been attributed by keller et al. (1978) to the campanian province. paterne et al. (1988), on the contrary, ascribed it to the "campanian ignimbrite series". a late glacial campanian marker tephra layer, labelled c-2 in paterne et al., 1988, has been recorded in the central mediterranean and correlated with the 12 ka b.p. campi flegrei eruption of neapolitan yellow tuff. the main holocene campanian tephra layers are linked to the somma-vesuvio activity. the most diffused marker layers are z-1, correlated to the somma-vesuvio avellino eruption (ca 3800 b.p., rolandi et al., 1998) and the tephra related to the a.d. 79 plinian eruption. they both feel the effect of the different direction of emplacement of fall products, so z-1 is mainly recorded in the east mediterranean, whereas a.d. 79 tephra is better represented in the central mediterranean. the present paper investigates in detail the tephra interbedded to the sedimentary records in two gravity cores of the southern tyrrhenian sea. the aims of the research are: to definitely identify the presence of a single or of more than one tephra layer of campanian origin in the age range 40-25 ka b.p., that encompasses all the 14c dating obtained on paleosols underlaying campanian ignimbrite deposits, to point out the distribution of the tephra layers and, eventually, to hypothesize a source for the pyroclastic products. in this regard, the work investigates gravity cores located near the campanian tyrrhenian coastal area, since the emplacement of campi flegrei and vesuvio products is more probable in this area, and uses sedimentological and biostratigraphic data as a support to chronologically locate the identified tephra layers. the present work is part of a multidisciplinary research that involved, through the last five years, geologists, sedimentologists, palinologists, palaeontologists and volcanologists, aiming to investigate environmental and climatic evolution of the southern tyrrhenian sea through high resolution records. the results of these researches are here reported only when useful to argue tephrostratigraphical conclusions. more detailed information about strictly sedimentological and palaeontological aspects can be found in buccheri et al. 2002a,b. few chemical data on glass shards and preliminary tephrostratigraphical considerations have been reported by one of the authors (r.m.) in buccheri et al. 2002a. the present paper represents a step forward, using new tephra and mineral characterization on the two cores and on-land comparison samples, and revising the upper pleistocene tephrostratigraphical record in the whole tyrrhenian area. 22.. eexxppeerriimmeennttaall 22..11 tteepphhrraa llaayyeerrss iinn tthhee ccoorreess two gravity cores located offshore the campanian tyrrhenian border have been investigated to reconstruct the tephrostratigraphical record of the area. the first core, named c106 (ϕ = 40°29'32'', λ = 14°42'32'', depht = 292 m) is located in the salerno gulf, directly offshore the sele river mouth, and is 6,40 m long. the second core, named c45 (ϕ = 39°45'10'', λ = 15°20'20'', depht = 1053 m) is located in the policastro gulf, in a valley-type depression of the sea floor, about 63 nautical miles sw of sapri town, and is 4.70 m long. figure 1 shows the location of investigated cores together with main deep sea morphological contours. both the cores consist of an alternance of clay, silt, silt-sandy and rare sandy layers, in which the coarse fraction is made up of organic (planktonic and bentonic foraminifers, pteropods) and inorganic material (pumice fragments, quartz and mica crystals). along the cored successions some coarse grained layers, mainly made up of sharp edged pumice fragments and crystals, displaying features of a primary volcanic deposition, have been fully investigated to reconstruct the complete tephrostratigraphical record (fig.2). along the core c106 the first tephra layer has been identified at 55.5 cm from the top and its lower limit is 110.5 cm. the whole thickness is 55 cm. the layer shows a sharp basal contact with the underlying clay layer. the basal part of the pyroclastic layer (110.588.5 cm) consists of whitish pumice fragments (sample a1(a)), overlain by a 10cm thick layer consisting of gray pumice and rare lava lithic fragments (sample a1(b)). both the samples display maximum clasts grain-size greater than 2mm and contain pumice fragments, a minor fraction of lava lithic fragments and rare limestone fragments. the second tephra layer of c106 has been identified at 565 cm from the top of the core and its lower limit is 579 cm. the whole thickness is 14 cm. the layer does not show a sharp basal contact with the underlying clay layer. the layer consists of some sublayers containing white and gray pumice fragments (sample a2), and passes towards the top to a dark clay level. all samples display maximum clasts grain-size greater than 2mm and contain pumice fragments and rare lava lithic fragments. juvenile fraction in both samples was represented by elongated pumice clasts, with very well developed elongated vesicles. along the c45 core three main tephra layers have been recognized. the first one has been identified at 25 cm from the top of the core and its thickness is about 7 cm. the layer is mainly made up of grey pumice fragments sample b1(b), maximum grain size 1 mm and rare lava and limestone lithic fragments, but in the basal part whitish pumice fragments are abundant sample b1(a). the second tephra layer of c45 core is located at 380 cm from the top and is 3 cm thick. it is made up of pumice fragments and glass shards, maximum grain 13new constraints on the occurrence ... size of clasts is 2 mm; no lithic fraction has been detected (sample b2). the third tephra layer is 460 cm deep and 3.5 cm thick. juvenile fraction is represented by glass shards and pumice fragments whose maximum grain-size is 1 mm; very rare lava lithic fragments have also been found (sample b3). mineralogical component percentage evaluation has been performed by counting at least 100 crystals for each level; the results of the analysis are shown in table 1. k-feldspar, biotite and clinopyroxene are almofig.1 map of the salerno and policastro gulfs with main submarine morphological contours and location of investigated cores. carta batimetrica dei golfi di salerno e policastro con l'ubicazione dei gravity cores studiati. table 1 mineralogical component percentage evaluation for all investigated tephra layers. valutazione semiquantitativa delle fasi minerali presenti all'interno dei livelli di tefra. core sample feldspar leucite biotite cpx garnet fe-ti oxides a1 (a) •• •• • c106 a1 (b) •• • • • a2 ••• • • b1 (a) •• •• • c45 b1 (b) •• • • • b2 •• • • • b3 •• • • • • l represents about 20% 14 st ubiquitous phases. only the topmost layer of both cores shows leucite and garnet among the mineral phases. chemical composition of glass fragments and crystal grains was determined by microprobe analysis using e.d.s. system on loose fragments of 0.5 mm grain-size, at cisag (centro interdipartimentale di servizio per analisi geomineralogiche) at university of naples federico ii. with regards to the chemical composition of glasses, the reported one represents a mean composition, obtained from at least ten punctual analyses on different glass shards. chemical composition of all the samples is reported in table 2. as a reference for correlations with the products of volcanic eruptions recorded in the field, table 3 reports the representative analyses of mineral grains for c45 core, chosen because it contains all the recognized tephra layers. the whole set of analytical data on minerals, both for tephra layers in the cores and for comparison samples, are at disposal upon request to the authors. 22..22 ccoommppaarriissoonn aannaallyysseess in order to better clarify the possible correlations, chemical analyses other than on the c106 and c45 pyroclastic layers have been performed. the comparison samples have been selected among the most widespread campi flegrei and somma vesuvio eruptions products ranging in age between about 40 and the present. the age range has been chosen taking into account the 14c ams dating that provided the chronostratigraphic framework for both cores, as reported in buccheri et al. (2002a,b) and in figure 2. the first comparison sample is represented by pumice fragments extracted from the pyroclastic fall layer directly underlaying the ignimbrite campana grey tuff at cologna, ne of salerno. the other comparison samples are represented by the somma-vesuvio codola and pomici di base eruptions products (rolandi, 1997), samples courtesy of prof. giuseppe rolandi. apart from this, to better define the characteristics of y-3, prof. keller has been asked a little sample of the fig. 2 stratigraphic succession of c45 and c106 core with interbedded tephra layers and thickness of tephra layers. *data from buccheri et al., 2002a;**data from buccheri et al., 2002b; nc = not calibrated. successione stratigrafica delle carote c45 and c106 con indicazione dei livelli di tefra intercalati e dei relativi spessori. *dati da buccheri et al., 2002a;**dati da buccheri et al., 2002b; nc = età non calibrata. r. munno & p. petrosino 15 layer firstly ascribed to y-3, from the core rc9-191 of the ionian sea. the sample has been analysed using the same methods as the unknown layers object of the paper. the analysis of keller et al. (1978) had, in fact, been performed by x-ray fluorescence on a glass enriched sample and, at present, it is well known (rinaldi, 1979; narcisi & vezzoli, 1999) that punctual analytical methods (eds, wds, etc) best suit tephrostratigraphycal problems. the last comparison sample is split into two subsamples respectively of white and grey pumice fragments from the a.d. 79 eruption, extracted from the poggiomarino and zabatta outcrops. it has been analysed since its south-west trending diffusion makes its presence expected in the salerno gulf recent sedimentary record. table 4 reports sem-eds glass compositions for table 2 sem-eds glass composition recalculated to 100 water free of all the investigated tephra samples. n= number of analyses; standard deviation in parentheses. composizione sem-eds del vetro ricalcolata a 100 per i livelli di tefra esaminati. n= numero di analisi; deviazione standard in parentesi. sample c106 c106 c106 c45 c45 c45 c45 a1(a) a1(b) a2 b1(a) b1(b) b2 b3 n 11 10 21 10 12 11 11 sio2 55.36 (0.27) 56.54 (0.19) 62.63 (0.20) 54.86 (0.24) 56.04 (0.32) 62.41 (0.32) 61.53 (0.48) tio2 0.48 (0.05) 0.24 (0.03) 0.34 (0.06) 0.45 (0.08) 0.55 (0.07) 0.33 (0.10) 0.39 (0.06) al2o3 21.01 (0.17) 22.72 (0.28) 18.24 (0.12) 20.74 (0.20) 21.36 (0.14) 18.30 (0.29) 18.73 (0.17) feo* 4.07 (0.16) 2.36 (0.21) 3.15 (0.12) 3.93 (0.11) 3.39 (0.12) 3.17 (0.10) 3.16 (0.19) mno 0.17 (0.08) 0.13 (0.11) 0.15 (0.08) 0.13 (0.04) 0.09 (0.03) 0.15 (0.08) 0.23 (0.07) mgo 0.59 (0.06) 0.11 (0.06) 0.47 (0.08) 1.38 (0.09) 0.48 (0.08) 0.50 (0.09) 0.50 (0.10) cao 4.23 (0.29) 2.98 (0.15) 2.12 (0.10) 4.47 (0.24) 4.06 (0.31) 2.13 (0.10) 1.74 (0.06) na2o 5.83 (0.21) 7.39 (0.64) 4.15 (0.19) 5.37 (0.17) 7.13 (0.21) 4.30 (0.15) 6.05 (0.33) k2o 8.28 (0.44) 7.54 (0.76) 8.75 (0.14) 8.67 (0.29) 6.90 (0.30) 8.71 (0.08) 7.67 (0.21) d.i. 79.56 86.03 86.82 77.40 81.75 86.95 89.53 ne 22.10 24.89 0.00 22.78 22.88 1.07 8.24 feo* = total fe as feo feo* = total fe as feo table 3 representative microprobe analyses of mineral phases extracted from c45 core tephra layers. analisi in microsonda dei minerali rappresentativi estratti dai livelli di tefra della carota c45. leucite k-feldspar cpx cpx biotite amphibole sio2 54.50 63.48 51.18 43.96 36.00 33.68 tio2 0.11 0.10 0.43 1.55 3.53 1.89 al2o3 22.76 18.81 2.36 8.30 15.50 15.21 feo* 0.37 0.09 4.65 11.05 11.65 24.84 mno 0.02 0.05 0.12 0.12 0.08 1.02 mgo 0.08 0.18 16.22 10.26 18.03 4.30 cao 0.12 0.33 23.85 23.58 0.00 11.55 na2o 0.83 1.23 0.44 0.46 0.49 1.47 k2o 20.51 15.03 0.00 0.00 10.33 3.37 total 99.30 99.30 99.25 99.28 95.61 97.33 b1 (a-b) b2 k-feldspar cpx biotite magnetite sio2 63.60 49.31 35.81 0.29 tio2 0.13 0.57 4.56 6.23 al2o3 18.88 3.77 14.50 2.56 feo* 0.23 8.31 14.49 80.91 mno 0.03 0.36 0.23 0.87 mgo 0.13 13.53 15.41 1.58 cao 0.55 23.00 0.00 0.06 na2o 1.84 0.53 0.56 0.10 k2o 13.95 0.00 9.84 0.04 total 99.34 99.38 95.40 92.64 b3 k-feldspar cpx biotite amphibole magnetite sio2 63.58 49.01 35.40 38.15 0.36 tio2 0.24 0.49 4.79 1.94 5.22 al2o3 18.87 2.97 15.06 12.20 4.11 feo* 0.27 11.28 13.89 19.54 79.73 mno 0.02 0.71 0.17 0.48 0.57 mgo 0.07 11.31 15.70 8.83 2.58 cao 0.48 22.83 0.00 11.84 0.00 na2o 1.82 0.79 0.53 1.57 0.40 k2o 14.12 0.03 10.02 2.77 0.00 total 99.48 99.42 95.56 97.32 92.97 new constraints on the occurrence ... 16 the comparative samples. figure 3 reports the tas classificative plot (le maitre, 1989) for the investigated tephra layers and the comparison samples, and figure 4a reports the di-ne plot of armienti et al. (1983), more apt to the slighty saturated and alkali-rich rocks of campanian area. 33.. rreessuullttss aanndd ddiissccuussssiioonn the modal and chemical compositions of pyroclastic layers, identified in the two gravity cores, show two compositional fields, phonolitic s.l. and alkali-trachytic. the presence of a phonolitic layer table 4 sem-eds glass compositions recalculated to 100 water free for the comparative samples. n= number of analyses; standard deviation in parentheses. composizione sem-eds del vetro ricalcolata a 100 per i campioni di riferimento. n= numero di analisi; deviazione standard in parentesi. 1 2 3 4 5 6 7 8 n 10 xrf 10 10 8 11 9 15 sio2 61.52 (0.20) 61.78 62.76 (0.36) 57.87 (0.30) 62.45 (0.08) 56.46 (0.25) 54.88 (0.21) 61.01 tio2 0.37 (0.06) 0.44 0.36 (0.03) 0.58 (0.08) 0.35 (0.03) 0.42 (0.05) 0.44 (0.03) 0.40 al2o3 18.88 (0.15) 18.96 18.21 (0.16) 19.16 (0.20) 18.34 (0.08) 21.35 (0.18) 20.67 (0.11) 18.63 feo* 3.06 (0.12) 3.23 2.98 (0.21) 3.90 (0.16) 2.74 (0.14) 3.34 (0.17) 4.09 (0.16) 3.55 mno 0.23 (0.05) 0.17 0.17 (0.12) 0.16 (0.06) 0.13 (0.09) 0.21 (0.10) 0.23 (0.04) 0.05 mgo 0.47 (0.05) 0.59 0.25 (0.12) 0.63 (0.11) 0.35 (0.04) 0.56 (0.09) 0.67 (0.08) 0.77 cao 1.75 (0.08) 1.98 2.07 (0.15) 4.43 (0.46) 2.75 (0.09) 4.05 (0.28) 5.03 (0.17) 2.47 na2o 6.01 (0.24) 5.57 4.44 (0.19) 3.30 (0.27) 4.24 (0.08) 7.17 (0.23) 5.55 (0.15) 2.65 k2o 7.71 (0.20) 7.28 8.75 (0.26) 9.96 (0.54) 8.66 (0.06) 6.45 (0.21) 8.45 (0.28) 9.93 d.i. 89.48 86.86 88.18 78.47 85.98 80.81 77.67 80.77 ne 8.20 3.89 1.28 9.82 1.26 21.24 22.73 0.00 feo* = total fe as feo 11 pumice fragment from campanian ignimbrite pyroclastic fall deposit at cologna (salerno). 22 y-5 tephra from core rc9-191, in keller et al. (1978), recalculated water free. 33 y-3 tephra from core rc9-191, sample courtesy of prof. j. keller. 44 pumice fragment from somma vesuvio codola eruption pyroclastic fall products, sample courtesy of prof. g. rolandi. 55 pumice fragment from somma vesuvio pomici di base eruption pyroclastic fall products, sample courtesy of prof. g. rolandi. 66 white pumice fragment from somma vesuvio ad 79 eruption pyroclastic fall deposit from the poggiomarino outcrop. 77 grey pumice fragment from somma vesuvio ad 79 eruption pyroclastic fall deposit from the zabatta (san giuseppe vesuviano) outcrop. 88 unit c ignimbrite matrix glass from scarafea (signorelli et al., 1999). fig. 3 tas classificative plot for investigated tephra layers and for comparison samples. for comparison samples symbols legend see table 4. diagramma classificativo tas per i livelli di tefra e per i campioni di riferimento. per la legenda dei simboli dei campioni di riferimento vedi tabella 4. r. munno & p. petrosino in the higher part of the c106 (samples a1(a) and a1(b), tab.2) and c45 (samples b1(a) and b1(b), tab.2) core makes it possible to hypothesize the relationship with the somma-vesuvio a.d. 79 eruption (samples 6 and 7, tab.4). the fall phase of this eruption, in fact, was dispersed towards the salerno gulf. besides this, the change in colour (from white to gray) and in composition (from phonolitic to tephry-phonolitic) of pumice fragments is a diagnostic feature for a.d. 79 eruption products. moreover, garnet is a typical mineralogical phase for white pumice fragments as leucite is for gray. the tephra layers alkali-trachytic in composition, found both in c106 and c45, represented by samples a2 and b2 (tab.2), respectively, could be related to somma-vesuvio first activity, namely to codola (25.1±0.4 ka b.p. alessio et al., 1974 – sample 4, tab.4) and pomici di base (18.3±0.18 ka b.p. andronico et al., 1995– sample 5, tab.4) eruptions, but also repeat the general chemical features of campi flegrei products. the dispersal of somma-vesuvio codola eruption fall products is, at present, not well known, but the comparison of si/ca ratio in codola and in sample a2 and b2 juvenile fraction makes it possible to exclude the correlation (fig.3, 4). as regards the pomici di base eruption products, even if the chemical composition is quite comparable, reconstructed fall products distribution is towards the ne from vesuvio and not in good agreement with the presence of the layer in the salerno gulf. besides this, the age of pomici di base eruption does not fit the 14c age of 26030±150 y b.p (buccheri et al., 2002a) and of 25570±110 y b.p. (buccheri et al., 2002b) obtained on the microfossils in the clay layer directly underlying the tephra, respectively in the c106 and in the c45 core. this is very reliable since: in c45 core a 14c ams age of 19490±110 y b.p. has been recorded in the clay 70 cm above the pyroclastic layer, in c106 core a calibrated 14c ams age of about 19.7 ka b.p. has been recorded in the clay 100 cm above the pyroclastic layer (see fig.2) no evidence of hiatuses in sedimentation is present along these clay layers. a2 and b2 tephra, however, find a very good correspondence in mineralogical content and chemical composition (tab.4) of y-3 tephra found in the ionian sea. besides this, in core rc9-191, investigated by keller et al. (1978), the dating of sapropels gave an age of about 26.000, well fitting the paleontological age obtained for the same layer in the two cores investigated here. as to the third pyroclastic layer in the c45 core, represented by sample b3, it repeats the composition of the fall products of the campanian ignimbrite eruption sampled at cologna. apart from this, it well resembles the composition of y-5 marker layer as reported in k e l l e r e t a l . ( 1 9 7 8 ) , d e f i n i t e l y c o r r e l a t e d t o t h e campanian ignimbrite in narcisi and vezzoli (1999), and that of the comparison sample. the attribution of lowermost layer to y-5 is consistent with the presence of 25 cm thickness of pelagic sediments between the layer and the clay level dated at about 26 ka b.p. in c45 core, taking into account a sedimentation rate of about 1,7 cm/ka, as deduced by buccheri et al. (2002a). 17 fig. 4 d.i. ne plot for investigated tephra layers and for comparison samples. for comparison samples symbols legend see table 4. diagramma d.i. ne per i livelli di tefra e per i campioni di riferimento. per la legenda dei simboli dei campioni di riferimento vedi tabella 4. new constraints on the occurrence ... 44.. ccoonncclluussiivvee rreemmaarrkkss the results of the tephrostratigraphical investigation of c45 and c106 tephra layers are so summarized: layer b3 of c45, the oldest tephra layer identified, is correlable to the y-5 marker layer and to the campanian ignimbrite basal pumice fall. layer b2 of c45 and layer a2 of c106 represent the product of the same volcanic event and have been correlated to the y-3 marker layer. layer b1(a,b) of c45 and layer a1 (a,b) of c106 represent the pumice fall products of the a.d. 79 sommavesuvio eruption. in order to confirm the presence of two different tephra layers in the 4025 ka time-span, the tephrostratigraphical literature reporting data for primary tephra layers in the tyrrhenian sea has been revised (paterne 1985; paterne et al., 1986; paterne et al., 1988; mccoy and cornell, 1990; calanchi et al., 1994). the revision of data entailed the recovering of all stratigraphical relations, modal compositions and chemical analyses of juvenile fraction and, where available, of mineral phases of tephra layers identified in many cores and new correlations have been made in the light of the obtained results. tab. 5 reports these new correlations that confirm the presence of y-3 tephra layer in southern tyrrhenian sea and along the campanian coast, whereas y-5 results more widely dispersed (fig. 5). 18 fig. 5 sketch map of tyrrhenian sea reporting the occurrence of y-3 and y-5 primary tephra layers, as deduced from the revision of tephrostratigraphic literature regarding the tyrrhenian sea and from present paper data. circles indicate coring sites; black area in the circle indicates the occurrence of y-3 tephra, dashed area in the circle indicates the occurrence of y-5 tephra. for core references see table 5. schema del mar tirreno che riporta la presenza dei livelli marker y-3 and y-5, dedotta dalla revisione della letteratura riguardante la tefrostratigrafia del tirreno e da dati del presente lavoro. i cerchi indicano l'ubicazione delle carote; l'area nera nel cerchio indica la presenza all'interno della carota del marker y-3, l'area tratteggiata nel cerchio indica la presenza all'interno della carota del marker y-5. per il riferimento alla carota vedi tabella 5. table 5 sem-eds glass composition of y-3 and y-5 tephra layers occurring in the tyrrhenian sea. composizione sem-eds dei vetri dei livelli di tefra y-3 and y-5 reperiti in alcune carote del mar tirreno. y-5 y-5 y-5 y-5 y-3 y-3 y-3 core ket 8003 ket 8004 ket 8011 ket 8022 ket 8003 ket 8004 ket 8011 ° ° °° ° ° ° °° sio2 62.29 62.46 61.90 63.19 60.42 60.59 59.90 tio2 0.36 0.36 0.34 0.00 0.40 0.23 0.36 al2o3 19.54 19.59 19.63 19.45 20.18 20.08 20.19 feo* 2.75 2.49 2.58 2.66 2.34 2.43 2.46 mno n.d. n.d. n.d. n.d. n.d. n.d. n.d. mgo 0.11 0.11 0.12 0.00 0.08 0.04 0.07 cao 1.63 1.63 1.88 1.73 3.38 3.16 3.56 na2o 5.99 6.01 5.86 5.69 3.92 4.39 4.59 k2o 7.33 7.35 7.69 7.27 9.28 9.08 8.87 ° in paterne et al., 1986 °° in paterne, 1985 feo* = total fe as feo r. munno & p. petrosino the presence of two alcali-trachytic tephra layers offshore the tyrrhenian coast, namely b2 and b3 in c45, separated by the deposition of pelagic sediments, makes it possible to hypotesize, in the 40-25 ka b.p. time span, the occurrence of two distinct intense volcanic events with a widely dispersed associated fall phase. the different age, together with the slightly different chemical composition, suggests that no link exists between them, apart from the source. the lower layer (b3 in c45) is well linkable to the campanian ignimbrite eruption, that we can now term first campanian ignimbrite, and its presence in the policastro gulf core well agrees with the distribution hypothesized for the associated fall phase by rosi et al. (1999). the sequence cored in c106, offshore the sele river mouth, where no record of y-5 has been found, probably stops before encountering this tephra layer. the topmost alkali-trachytic layer (a2 in c106 and b2 in c45) tesifies to the presence of the y-3 marker layer in the tyrrhenian area, and no clear attribution to a recognized volcanic event is at present possible. however, it can be interpreted as the record of an eruptive event from the campanian area. the absence of a somma-vesuvio eruption as the origin of the layer, restricts the field of possible sources to campi flegrei. chemical features of y-3 are quite peculiar, and distinguish it from y-5, here definitely linked to campanian ignimbrite. it can be concluded that the presence of this layer accounts for the hypothesis that what is found in the field and ascribed to the campanian ignimbrite eruption may be the result of at least two distinct eruptive episodes, each with an associated fall phase. y-3 can be considered the record of another eruptive event, that we term second campanian ignimbrite eruption. the occurrence in volcanological literature of 14c dating ranging between 40 and 25 ka can so be read as the result of the sampling of different paleosoil, underlying somewhere the older, elsewhere the younger pyroclastic deposit. as to the chemical composition, a slight chemical difference in the composition of campanian ignimbrite units has been detected by signorelli et al. (1999). according to these authors, the last unit of c.i. (sampled in the northern area of naples, giugliano municipality, in a quarry at the scarafea locality) is much richer in k than the first one and seems well to resemble the composition of y-3. we hypothesize that this unit can be the pyroclastic flow associated to the fall phase emplacing y-3. this hypothesis can be supported by the recorded presence of a paleosol between the campanian ignimbrite tuff and the topmost pyroclastic flow deposit at giugliano and by the 40ar/39ar dating of the same deposit, that results much younger than campanian ignimbrite (rolandi et al., 2003). at present more field studies are necessary, aimed at mapping the two different ignimbrite deposits linked to y-5 and y-3 tephra marker layers. aacckknnoowwlleeddggmmeenntt this research, within the project "impact of natural events on biotic communities in the last 20 ka bp climatic and volcanic events", was supported by prin 1998, chief scientist prof. g. ciampo. prof. t.s. pescatore kindly offered the c106 core. the authors wish to gratefully thank prof. j. keller, who kindly supplied a tephra sample from core rc9191, and prof. g. rolandi, for supplying some comparison samples. prof. l. lirer is thanked for reading an early draft of the paper. rreeffeerreenncceess alessio m., bella f., improta s., belluomini g., cortesi c. & turi b., 1971 university of rome carbon-14 dates ix. radiocarbon, 1133--22, 395-411. alessio m., bella f., improta s., belluomini g., calderoni g., cortesi c. & turi b., 1973 university of rome carbon-14 dates x. radiocarbon, 1155--11, 165-178. alessio m., bella f., improta s., belluomini g., calderoni g., cortesi c. & turi b., 1974 university of rome carbon-14 dates xii. radiocarbon, 1166--33, 358-367. andronico d., calderoni g., cioni r., sbrana a., sulpizio r. & santacroce r., 1995 geological map of somma-vesuvio volcano. period. mineral., 6644((11--22)), 77-78. armienti p., barberi f., bizouard h., clocchiatti r., innocenti f., metrich m., rosi m. & sbrana a., 1983 the phlegraen fields: magma evolution within a shallow chamber. j. volcanol. geotherm. res., 1177, 89-311. barberi f., innocenti f., lirer l., munno r. & pescatore t.s., 1978 the campanian ignimbrite: a major prehistoric eruption in the neapolitan area (italy). bulletin volcanologique, 4411,1-22. buccheri g., bertoldo g., coppa m.g., munno r., pennetta m., siani g., valente a. & vecchione c., 2002a studio multidisciplinare della successione sedimentaria tardo-quaternaria proveniente dalla scarpata continentale del golfo di policastro (tirreno meridionale). boll. soc. geol. it., 112211, 187-210. buccheri g., capretto g., di donato v., esposito p., ferruzza g., pescatore t., russo ermolli e., senatore mr., sprovieri m., bertoldo m., carella d. & madonia g., 2002b a high resolution record of the last deglaciation in the southern tyrrhenian sea: environmental and climatic evolution. marine geology, 118866,, 447-470. calanchi n., gasparrotto g. & romagnoli c., 1994 glass chemistry in volcaniclastic sediments of odp leg 107, site 650, sedimentary sequence: provenance and chronological implications. j. volcanol. geotherm. res., 6600,, 59-85. calderoni g., vesica p. & turi b., 1993 radiocarbon dating of the campanian ignimbrite (tufo grigio campano auct.): towards a definition of the main emplacement phase. symposium "quaternary stratigraphy in volcanic areas", roma, september 20-22. abstracts, 17. cassignol c. & gillot p., 1982 range and effectiveness of unspiked potassium-argon dating: experimental ground work and application. in g.s. odin (ed.) "numerical dating in stratigraphy",160-179. curtiss g.h., 1966 the problem of contamination in obtaining accurate dates of young geologic rocks. 19new constraints on the occurrence ... in: oa shaeffer and j zahringer eds. potassium argon dating, springer berlin. deino a.l., courtis g.h. & rosi m., 1992 40ar/39ar dating of campanian ignimbrite, campanian region, italy. int geol congr kioto, japan, abstracts, vol 3, p 2654. deino a.l., courtis g.h., southon j., terrasi f., campaiola l. & orsi g., 1994 14c and 40ar/39ar dating of the campanian ignimbrite, phlegraean fields, italy. abstracts icog, berkley, ca, u.s.a. de vivo b., rolandi g., gans p.b., calvert a., bohrson w.a., spera f.j. & belkin h.e., 2002 new constraints on the pyroclastic eruptive history of the campanian volcanic plain (italy). mineralogy and petrology, 7733, 47-65. fisher r.v., orsi g., ort m. & heiken g., 1993 mobility of large-volume pyroclastic flow emplacement of the campanian ignimbrite, italy. j. volcanol. geotherm. res., 5566, 205-220. keller j., ryan w.b.f., ninkovich d. & altherr r., 1978 explosive volcanic activity in the mediterranean over the past 200,000 years as recorded in deepsea sediments. bull. geol. soc. am., 8899, 591-604. le maitre r.w. ed, 1989 a classification of igneous rocks and glossary of terms. blackwell scientific publications, oxford, 193 pp. mccoy f.w. & cornell w., 1990 volcaniclastic sediments in the tyrrhenian basin. proc. ocean drilling program, 110077, 291-306. narcisi b. & vezzoli l., 1999 quaternarnary stratigraphy of distal tephra layers in the mediterranean-an overview. global and planetary change, 2211, 31-50. paterne m., 1985 reconstruction de l'activitè explosive des volcans de l'italie du sud par téphrochronologie marine. thèse dr. sciences paris-sud., 144 pp. paterne m., guichard f., labeyrie j., gillot py. & duplessy j.c., 1986 tyrrhenian sea tephrochronology of the oxygen isotope record for the past 60,000 years. marine geology, 7722, 259-285. paterne m., guichard f. & labeyrie j., 1988 esplosive activity of the south italian volcanoes during the past 80,000 years as determined by marine tephrochronology. j. volcanol. geotherm. res., 3344, 153-172. rinaldi r., 1979 la microanalisi elettronica: strumentazione e applicazioni mineralogico-petrografiche. rend. soc. it. min. pet., 55((22)), 507-526. rolandi g., 1997 the eruptive history of sommavesuvius. in: volcanism and archaeology in mediterranean area (cortini m. and de vivo b. eds.). research signpost, trivandrum, india 7788. rolandi g., petrosino p. & mcgeehin j., 1998 the interplinian activity at somma-vesuvius in the last 3500 years. j. volcanol. geotherm. res., 8822, 1952. rolandi g., bellucci f., heizler m.t., belkin he. & de vivo b., 2003 tectonic controls on the genesis of ignimbrites from the campanian volcanic zone, southern italy. mineralogy and petrology, 7799, 331. rosi m., vezzoli l., aleotti p. & de censi m., 1996 interaction between caldera collapse and eruptive dynamics during the campanian ignimbrite eruption, phlegraean fields, italy. bull. volcanol., 5577, 541-554. rosi m., vezzoli l., castelmenzano a. & grieco g., 1999 plinian pumice fall deposit of the campanian ignimbrite eruption (phlegraean fields, italy). j. volcanol. geotherm. res., 9911((22-44)), 179-198. scandone r., bellucci f., lirer l. & rolandi g., 1991 the structure of the campanian plain and the activity of the neapolitan volcanoes (italy). j. volcanol. geotherm. res., 4488, 1-31. signorelli s., vagelli g., francalanci l. & rosi m., 1999 origin of magmas feeding the plinian phase of the campanian ignimbrite eruption, phlegrean fields (italy): constraints based on matrix-glass and glass-inclusion compositions. j. volcanol. geotherm. res., 9911((22--44)), 199-220. thunell r., federman a., sparks s. & william d., 1979 the age, origin, and volcanological significance of the y-5 ash layers in the mediterranean. quaternary res., 1122, 241-253. vezzoli l., 1988 island of ischia. cnr, quaderni della ricerca scientifica 10, roma, 132 pp. 20 ms. ricevuto il 15 luglio 2003 testo definitivo ricevutol’11 novembre 2003 ms. received: july 15, 2003 final text received: november 11, 2003 r. munno & p. petrosino impaginato baioni ddrraaiinnaaggee nneettwwoorrkk aanndd eenneerrggyy rreelliieeff ooff mmaaddeeiirraa iissllaanndd ((ppoorrttuuggaall)):: pprreelliimmiinnaarryy nnootteess ddaavviiddee bbaaiioonnii11,, ddoommiinnggooss rrooddrriigguueess22 && ggiiuulliiaannoo ggaalllleerriinnii11 1università degli studi di urbino,campus scientifico, istituto di dinamica ambientale loc. crocicchia, 61029 italy. 2c.c.b.g. universidade da madeira,campus da penteada, 9000 funchal, portugal. abstract a geomorphological study, integrated with satellite imagery analysis, has been carried out in the madeira island to identify the influence of neotectonics on the landscape. drainage network and energy relief are the main geomorphological indexes used to identify recent uplift. the drainage anomalies and areas of high relief energy, often coincident, are not explainable by means of the local meteoclimatic conditions. some peculiar anomalies, such as hook-like shapes and torsions of the network, distributed on lineaments that coincides with those detectable from satellite images, indicate a differential direction of central block, symptom of a prevailing tectonics of uplift with a probable horizontal component. riassunto reticolato idrografico ed energia del rilievo dell’isola medeira (portogallo): note preliminari. e’ stato affrontato uno studio geomorfologico preliminare integrato con analisi di immagini da satellite nell’isola di madeira per valutare l’influenza della neotettonica sulla morfologia. i principali indicatori per identificare il recente sollevamento si sono rivelati il reticolo idrografico e l’energia del rilievo. le anomalie del drenaggio e le aree ad alta energia del rilievo sono spesso coincidenti e sembrano non essere condizionate dalle condizioni meteoclimatiche dell’isola e risultano essere in relazione ad alcune lineazioni tettoniche evidenziate nelle immagini da satellite. tale situazione morfologica indica un sollevamento differenziale del blocco centrale con una probabile componente orizzontale. keywords: drainage network, energy relief, neotectonics, madeira island. parole chiave: reticolo di drenaggio, energia del rilievo, neotettonica, madeira il quaternario italian journal of quaternary sciences 1155(2), 2002, 271-274 11 iinnttrroodduuccttiioonn a stream channel network analysis has been carried out on the existing cartography available at the 1:50.000 scale (i.g.a. madeira, cf. table attached). on the basis of the detected patterns, network anomalies, that were not justifiable by means of terrain lithology and structural tectonics, were identified. concurrently, the map of relief energy was derived so that further morphotectonic information via an integrated analysis could be obtained. 22 ggeeoollooggiiccaall aanndd ggeeoommoorrpphhoollooggiiccaall sseettttiinngg madeira island is located in the north atlantic, 900 km southeast of lisbon. it has an area of 728 km2 and 265000 inhabitants. it is of volcanic origin, miocene period, and considered as the present location of a hotspot that also originated the desertas islands (which belong to the same volcanic complex), porto santo island and the seamounts seine, unicorn, ampere, coral patch and ormond. madeira has in its central region swarms of vertical dikes, normal faults, graben structures and cinder cones, parallel to the long axes of madeira (ew) an area characteristic of volcanic rift zones (biancotti, 2001; geldmacher & hoernle, 2000). lithostratigraphically the geology of madeira island can be divided into three units. the first, a basal unit, was formed during the late miocene to pliocene and is mainly formed by volcanic breccias and pyroclastic deposits. the second, the middle unit, is composed by basaltic lava flows and formed from the pliocene to the pleistocene. the third, the upper unit, consists of scoria cones and intra-canyon lava flows formed during the renewed volcanic stage of evolution of the island (geldmacher & hoernle, 2000). the orography is characterized by a strong relief with altitudes that reach 1860 m, the average altitude is of 700 m. average rainfall values vary from 600 mm in the southern coast to 3000 mm in the areas of high altitude. the lithology and the structure of the volcanic body, which originated the island itself, mainly influence the morphology of madeira island. climatic changes, the last periods of quaternary volcanic activity (mata, 1996), neotectonics and sea level variations have played an important role in the definition of the morphological configuration. in addition, intensive anthropic impacts, essentially concentrated on coastal areas, have caused further changes to the landscape. the most active processes are coastal erosion (the northern shore faces ne and n winds, hence it is affected by active marine ero272 d. baioni, d. rodrigues & g. gallerini f ig . 1 d ra in a g e s ys te m o f m a d e ir a is la n d ( i. g .a . m a d e ir a , 1 :5 0 .0 0 0 m o d ifi e d a n d r e d u ce d ). s o m e n e tw o rk a n o m a lie s a n d m a in d ra in a g e p a tt e rn t yp e s a re h ig h lig h te d . e n e rg y re lie f m a p ( to p r ig h t) . s is te m a d i d re n a g g io d e ll' is o la d i m a d e ir a ( i. g .a . m a d e ir a , 1 :5 0 .0 0 0 m o d ifi ca ta e r id o tt a ). s o n o e vi d e n zi a te a lc u n e a n o m a lie d e l re tic o lo e l e p ri n ci p a li tip o lo g ie d e i p a tt e rn d i d re n a g g io . c a rt a d e ll' e n e rg ia d e l r ili e vo ( in a lto a d e st ra ). 273drainage network and energy relief ... sion whereas the southern shore results to be more protected), run off erosion and chemical weathering of pyroclastic lithologies. the drainage network is heavily incised and vertical erosion dominates. 22..11 ddrraaiinnaaggee nneettwwoorrkk aannaallyyssiiss the study of the drainage network (fig.1) indicates at least 2 main patterns, parallel diverging and dendritic ones, and reveals that generally the existing basins are distributed in a centrifugal manner around the central relief. the ribera de janela basin represents an exception; it develops by overlapping in an anomalous way transversally to the dominant drainage direction. it is likely that such a basin represents a more recent formation compared to the surrounding drainage system. a significantly diverging drainage pattern extends in the area south of the main divide, between p.ta do sol and p.to moniz (wnw part), in the area between funchal and machico (sse part) and in the area north of the main divide between the arch of st. gorge and faial. diverging nets are typically derived from previous alluvial fans and/or pediment surfaces (cfr. nesci & savelli, 2001). where it is found, diverging drainage developed independently both from the geological and structural setting and from the age of terrain. sometimes together with diverging patterns a parallel net prevail, especially in the sw coast sector of the island. parallel streams in this diverging net could be derived from the ancient topographic configuration on a more pronounced slope. a dendritic-feathered pattern prevails in the central part of the island, it generally develops on rocks of uniform sedimentary units. this pattern shows a very high drainage density. anthropic modifications affected the channel network around densely populated and intensively cultivated coastal areas. a detailed analysis has allowed the identification of network branches characterised by an anomalous pattern (torsions, elbow-like, rectilinear and barbed segments). the occurrences of such anomalous branches, that can be correlated to lineaments (fig.1, fig.2), have been interpreted as tectonic constraint of the network. in fact, they are not justifiable by other causes (selective erosion, slope gradients, anthropogenic factors, etc.). this is also confirmed by the exceptional correspondence that exists between the majority of the lineaments and those detectable from satellite image interpretation (cf. fonseca & alii,1998 a and b) 22..22 rreelliieeff eenneerrggyy aannaallyyssiiss the relief energy analysis has been conducted by extraction of an energy map. topographic maps (1:50.000 scale) of the madeira island have been divided into 2 by 2 cm. squares (equivalent to a linear scale of 1.000 m on the ground) (cfr. klein & antun, 1983). subsequently the squares have been numbered according to an orthogonal co-ordinate system. for every square minimum and maximum elevation have been estimated using contour lines as references (equidistance equals 25 metres). the relief energy has been obtained by subtracting the minimum from the maximum value. the obtained map presents two areas of high relief energy. one extends essentially on the central region of the island, occupied by the central massif, the other is located in the northern part between p.to moniz fig.2 spot image of madeira island (project corine land cover ilha da madeira.cnig. secretaria regional do equipamento social.governo regional da madeira) immagine da satellite dell'isola di madeira (project corine land cover il ha da madeira.cnig. secretaria regional do equipamento social.governo regional da madeira) 274 and p.ta delgata, where values are certainly enhanced by the ongoing erosion due to its peculiar exposition. to highlight the spatial similarities among all high relief energy areas and the high drainage density, all the most significant anomalies of the drainage network are concentrated in these high relief energy areas. 33 ccoonncclluussiioonnss this study aimed at highlighting the presence of some landscape anomalies in specific areas of madeira island. these areas are separated by main lineaments that are easily detectable from satellite imagery (fig. 2). the diverging/parallel pattern, that corresponds to low energy relief zones, indicates the presence of a palaeo-landscape that has been partially reshaped by erosive processes only in the south and north-east parts of the island. when compared to others, these sectors seem to have been subjected to a minor uplift. in contrast, the central part of the island shows a dendritic drainage pattern with high drainage density and many anomalous tracts of the rivers (captures elbows, torsions, barbed rivers, etc.). this generally indicates drainage in evolution. anomalous trend of the divides shows strong headwater regressive erosion with a clear tendency to hillslope retreats. the high-energy relief is found just in this sector, even though in places (e.g. coastal area) such a situation can result from the high denudation rate of the northerly facing basins. the north-west part of the island is characterised by the anomalous basin of ribera de janela river elongated in nwse direction. the shape of this basin that shows a very low energy relief probably represents the response of this mountain sector to a very recent evolution. this assumption is justified by the anomalous length of the stream when compared to all rivers of the island and by the incomplete erosion of the palaeosurfaces of plan de serra, which is most likely, a remnant of ancient landscape. in conclusion, we identify several areas that present a different tectonic behaviour by means of the geomorphological analyses reported above. in particular, the central area appears to be the most affected by dynamics of uplifting whereas lateral areas seem to be substantially stable or however interested by minor uplifting. torsions of the stream channels in correspondence of the two principal nwse lineaments, might be due to different horizontal components: clock-wise movements in the southern portion and anti clock-wise movements in the northern one. aacckknnoowwlleeddggeemmeennttss our thanks to prof. o. nesci for useful discussions. rreeffeerreenncceess carvalho a.m.g. & brandao j.m. (1991) geologia do arquipelago da madeira. museu nactional de historia natural (univ.lisboa), pp. 170. fonseca p.e., mata j. & domingos r.(1998a) preliminary data on tectonic lineaments from madeira island. geologos revista do dept.de geol.da fac.de cien.da univ.do porto 2, 89-90 fonseca p.e., mata j.& munha j.(1998b) tectonic lineaments from madeira island evidenced from satellite image analysis and preliminary geological data. actas do v congresso nactional do geologia, lisboa comun.inst.geol.min., 84(1), 101-104. geldmacher, j. & hoernle, k., (2000). the 72 ma geochemical evolution of the madeira hotspot (eastern north atlantic): recycling of palaeozoic (£ 500 ma) oceanic crust. earth planet. sci. lett. 183,. 73¯92. klein v. & antun s. (1983) a morphostructural analysis of the adriatic seabed relief energy on the basin of a bathymetrical map on the scale 1:750.000. bulletin of the inqua neotectonics commission, 6,40. mata j. (1996) petrologia e geoquimica das lavas da ilha da madeira:implicacoes para os modelos de evolucao mantelica.tese de doutoramento (univ.lisboa), pp. 471 nesci o. & savelli d. (2001) diverging drainage in the umbria-marche apennines (central italy). convegno "uplift and erosion: driving processes and resulting landforms: dynamic relations between crustal and surficial processes", september 20 and 21, certosa di pontignano (siena). (abstract) d. baioni, d. rodrigues & g. gallerini ms. ricevuto il 20 ottobre 2002 testo definitivo ricevuto il 4 febbraio 2003 ms. received: october 20, 2002 final text received: february 4, 2003 imp.carraro_giardino considerazioni sui criteri di correlazione tra unita’ stratigrafiche continentali quaternarie francesco carraro1 & marco giardino1 1dipartimento di scienze della terra, università degli studi di torino – francesco.carraro @unito.it riassunto: carraro f. & giardino m., considerazioni sui criteri di correlazione tra unità stratigrafiche continentali quaternarie. (it issn 0394-3356, 2004). nella letteratura geologica italiana sul quaternario continentale vengono spesso proposte correlazioni tra unità stratigrafiche l.s. (intese come corpi sedimentari o superfici di erosione) presenti in aree diverse, tra successioni di più unità stratigrafiche l.s. presenti in aree diverse o, infine, tra unità stratigrafiche s.l. ed “episodi” (intesi come intervalli di tempo, di durata molto variabile, durante i quale si sono instaurate e sono persistite determinate condizioni) climatici o tettonici. le correlazioni possono essere basate sulla litofacies, sulla posizione stratigrafica o su elementi cronologici di riferimento. dall’analisi dello sviluppo logico dei lavori in cui vengono avanzate proposte di correlazione si può ricavare che queste sono spesso supportate da uno o più di uno assunti. nel lavoro vengono analizzati criticamente tali assunti, giungendo alla seguente serie di considerazioni. nella maggior parte dei casi le successioni continentali sono decisamente lacunose, nel senso che non vi sono rappresentati tutti gli episodi sedimentari o erosivi in cui è consistita l’evoluzione geologica di cui rappresentano il riscontro; diverse unità di rango stratigrafico confrontabile possono corrispondere ad intervalli di tempo apprezzabilmente diversi. la durata dei diversi episodi climatici che controllano la sedimentazione o l’erosione può essere molto diversa. gli studi sulla tettonica recente ed in atto stanno dimostrando che lo stesso vale per le deformazioni sinsedimentarie. in contesti geodinamici caratterizzati da mobilità fra i fattori che controllano il sistema sedimentario continentale, oltre al ruolo “dinamico” dei fattori esogeni ed endogeni va aggiunto quello “statico” della diversa erodibilità delle formazioni rocciose via via esumate dall’erosione. quest’ultimo è responsabile della forte inerzia con cui il sistema risponde ai primi due gruppi di fattori. ne deriva la forte diacronicità che può caratterizzare nel loro sviluppo complessivo la base ed il tetto di un’unità sedimentaria o una superficie di erosione in tutta la sua estensione e la probabile confrontabilità di questa con la durata dei singoli episodi. viene poi esaminato il reale significato delle datazioni numeriche: queste possono essere affette da tre tipi di condizionamenti, il più importante dei quali è quello della effettiva associazione dell’elemento che si data con l’episodio che si intende datare. il secondo è rappresentato dalla possibile apertura del sistema chimico. il terzo condizionamento è quello, inevitabile, del margine di errore delle misure di laboratorio. da tutto quanto esposto sembra dovrebbe risultare sufficientemente documentato che correlazioni basate su un basso numero di datazioni sono molto deboli e discutibili. nel tentare delle correlazioni appare perciò opportuno spingersi, solo in presenza di un numero significativo di elementi di datazione, unicamente al livello o ai livelli che contengono gli elementi stessi e non all’intera unità sedimentaria, meno che meno alla successione in cui questa è compresa. qualsiasi altro tentativo resterà tale e come tale è opportuno sia presentato in eventuali lavori di sintesi. abstract: carraro f. & giardino m., a few remarks on the use of correlation criteria among quaternary continental stratigraphic units. (it issn 0394-3356, 2004). starting from a general definition of the term “correlation” (“demonstration of the lithological or chronological equivalence of two or more geological phenomena in different areas, by means of paleontological or physical evidence”) a discussion will be developed on the topic of stratigraphic correlations, which can be considered a “blind area” in the field of modern quaternary geology. in the italian geological literature concerning continental quaternary, correlation are frequently presented between stratigraphic units l.s. (meant as sedimentary bodies or erosional surfaces) of different areas, or between stratigraphic units s.l. and climatic or tectonic “episodes” (events meant as time intervals of various length, during which certain conditions started and persisted). correlations can in turn be based on lithofacies, stratigraphic position or chronological elements of reference. by analysing the logical development of scientific papers presenting correlation hypothesis, it can be drawn that correlations are often based on one or more than one of some arguments: a stratigraphic succession is an almost continuous record of geological evolution of an area, in the sense of a series of sedimentary bodies and erosional surfaces representing the whole group of sedimentary and erosional events taken place through time in that area; the time interval of formation of a stratigraphic unit can be compared by duration to the time interval of a climatic or tectonic event; the diacronicity (i.e. the difference between the minimum and maximum age) of the whole lenght of bottoms and tops of a stratigraphic unit s.l. is much shorter than time interval of a climatic or tectonic event; the stratigraphical units trace back to a single distinct climatic or tectonic event, in the sense of an event excluding the other; the available chronological elements are always characterized by absolute values and good resolution. in this paper arguments are critically analysed, and some consideration are derived. in the majority of cases, continental successions are quite full of lacunae, in the sense they do not represent a complete collection of sedimentary or erosional events describing the whole geological history of the area; stratigraphic units of different rank can correspond to quite different time intervals. also the duration of different climatic events controlling depositional or erosional processes can be quite different. up to date studies on recent and active tectonics are now showing the validity of the above considerations also for interpreting syn-sedimentary deformations. in geodynamic environments characterized by a mobility of factors controlling the continental sedimentary system, in addition to the dynamic role of exogenetic and endogenetic factors, a “static” control has to be considered, due to different erodibility of the through-time outcropping rock and sediment units. this latter is responsible for the strong inertia of the system response to the inputs from the first groups of conditioning factors. it derives a strong diacronicity along the whole lenght of bottoms and tops of sedimentary units and erosional surfaces; it also derives that stratigraphic units of the same rank can correspond to very different time intervals. in the paper field data and interpretations are presented and graphically illustrated to show how very different climatic or tectonic events can be testified by stratigraphic units of the same rank.then the real significance of numerical datings is analysed: these can be affected by three types of conditionings, the most important being the effective associations of dating elements to the events to be dated. the second is represented by the possible openings of the geochemical system. the third conditioning is the unavoidable errors of laboratory measures. from the above presented arguments it can be sufficiently documented that correlations based on a low number of dating elements are weak and open to challenge. in the tentative correlations is therefore suitable to go further only to the correlation of single sedimentary bodies containing dating elements, not to the whole sedimentary units, less than ever to the whole succession that comprises it. any other effort will remain an attempt and it is opportune to be presented as such in synthesis papers. parole chiave: correlazione, stratigrafia, continentale, forme, depositi, quaternario. keywords: correlation, stratigraphy, continental environment, landforms, deposits, quaternary. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 293-300 294 f. carraro & m. giardino 1. introduzione fra le attuali “zone d’ombra” della geologia del quaternario vanno sicuramente annoverate le problematiche relative alla correlazione fra unità stratigrafiche continentali quaternarie. a partire da una definizione generale di “correlazione” come “la dimostrazione dell’equivalenza di due o più fenomeni geologici in aree differenti”1, equivalenza che può essere di diversa natura (litologica, cronologica, di posizione stratigrafica, ecc.) e supportata da vari tipi di evidenze (paleontologiche, fisiche, ecc.)2, verranno svolte alcune considerazioni sul tema che risulta di fondamentale interesse non solo per una corretta ricostruzione dell’evoluzione geologica di un’area, ma anche per una sua adeguata rappresentazione cartografica geologica di base e geotematica. nella letteratura geologica italiana sul quaternario continentale vengono spesso proposte correlazioni: tra “unità stratigrafiche s.l.” distribuite in aree diverse. nel testo che segue con l’espressione “unità stratigrafiche s.l.” si intenderanno, oltre ai corpi sedimentari, anche le superfici di discontinuità che ne segnano la base o il tetto; tra successioni di più “unità stratigrafiche s.l.” presenti in aree diverse; tra “unità stratigrafiche s.l.” ed “episodi” climatici o tettonici (intesi come intervalli di tempo, di durata molto variabile, durante i quale si sono instaurate e sono persistite determinate condizioni). le correlazioni possono essere basate su: litofacies; posizione stratigrafica; elementi di riferimento (cronologici o di altra natura). dall’analisi dello sviluppo logico dei lavori in cui vengono avanzate proposte di correlazione si può ricavare che queste sono spesso supportate da uno o più di uno della seguente serie di assunti, non espressi esplicitamente ma facilmente desumibili: a) una successione stratigrafica costituisce un record continuo dell’evoluzione geologica, cioè la successione di corpi sedimentari e di superfici di erosione (unità stratigrafiche s. l.) rappresenta il riscontro di tutti gli episodi sedimentari o erosivi succedutisi nell’area; b) l’intervallo di tempo corrispondente alla realizzazione di un’unità stratigrafica s.l. è confrontabile per durata con quello di un episodio climatico o tettonico; c) il grado di diacronicità (cioè la differenza tra l’età minima e l’età massima) della base o del tetto di un’unità stratigrafica s.l. nel suo sviluppo complessivo è molto minore della durata di un episodio climatico o tettonico; d) le unità stratigrafiche s.l. sono riconducibili o a un solo episodio climatico o a uno tettonico, in ogni caso distinti tra loro nel senso che si ammette che quando agisce uno non agisca l’altro; e) gli elementi cronologici disponibili sono caratterizzati da un valore assoluto e da un buon grado di risoluzione. nell’analizzare criticamente gli assunti sopra riportati verranno presentate una serie di considerazioni, di volta in volta documentate da dati ed interpretazioni tratte da diversi casi di studio. 2. presunta completezza delle successioni stratigrafiche si prenda ad esempio una successione costituita dal corpo a dalla superficie di erosione b dal corpo c e della superficie di erosione d: in una ricostruzione generica tale successione rappresenterebbe il record dell’episodio sedimentario a seguito dall’episodio erosivo b, seguito a sua volta dall’episodio sedimentario c seguito infine dall’episodio erosivo d. come già ricordato, si tende cioè a considerare una successione di corpi sedimentari e di superfici di erosione come il riscontro di tutti gli episodi sedimentari ed erosivi succedutisi in una determinata area, anche se ci si rende conto della presenza di lacune che possono elidere parte degli stessi. a prescindere dal fatto ben noto che le successioni continentali presentino per loro natura lacune sedimentarie, la storia evolutiva ricostruita dalle successioni continentali quaternarie documenta che l’assunto “semplicistico” di cui sopra non sempre si verifica. si veda ad esempio la fig. 1: i numeri indicano gli episodi sedimentari o erosivi ed i corpi o le superfici corrispondenti. le diversi tonalità di grigio aiutano a contraddistinguerli. si notino le superfici di erosione di rango inferiore all’interno dei singoli corpi sedimentari che, assieme a quelle di rango maggiore, testimoniano gli episodi erosivi conservati. dall’esame della fig. 2 si deduce che naturalmente non è possibile una correlazione a priori tra una successione stratigrafica ed una successione di “episodi”. dall’evoluzione reale della colonna stratigrafica si osserva che nella successione stratigrafica finale mancano completamente i termini corrispondenti agli “episodi” 2, 3, 4 e 5: 3. presunta confrontabilità unità stratigrafica episodio tettonico o climatico circa il punto b), riguardante la “confrontabilità” della durata della realizzazione di un’unità stratigrafica s.l. con quella di un “episodio” tettonico o climatico, è altresì facilmente verificabile che diverse unità di rango stratigrafico confrontabile possono corrispondere ad intervalli di tempo apprezzabilmente diversi. o meglio: episodi tettonici o climatici di rango diverso possono avere come riscontro unità stratigrafiche s.l. dello stesso rango. ad esempio un corpo alluvionale di modesto spessore può rappresentare il riscontro di un unico 1correlation: demonstration of the equivalence of two or more geologic phenomena in different areas; it may be lithologic or chronologic. also, the condition or fact of being correlated (dictionary of geological terms. american geological institute r. b. bates & j.a. jackson (ed.s), 3rd ed., 1983, anchor books.). 2correlation: parallelization, the determination, on paleontological or physical evidence, of the equivalence in geologic age and stratigraphic position of two formations or other stratigraphic units in separate areas. geological nomenclature. royal geological and mining society of the netherlands, a. a. g. schieferdecker ed., 1959, gornichem. 295considerazione sui criteri di correlazione ... sedimentarie e sinmorfogenetiche: esse possono dare le stesse manifestazioni su intervalli di tempo di durata molto diversa. ad esempio, nel caso di zone di taglio regionali come quelle che interessano la catena alpina nel settore occidentale, sul lungo termine possono verificarsi prolungati episodi deformativi, in grado di caratterizzare in modo alquanto omogeneo estese aree (es. susa-chisone shear zone; giardino & polino, 1997). sul breve termine, singoli episodi locali possono determinare l’attivazione di singoli segmenti di faglia (fig. 3; es. aosta-ranzola, carraro et alii, 1994). queste manifestazioni non hanno carattere eccezionale e locale come si riteneva in passato, ma fanno parte delle normale evoluzione geologica e interagiscono e si sovrappongono agli effetti delle variazioni climatiche. e’ questo il caso delle ripetute deformazioni sinsedimentarie registratesi a vari livelli della successione “villafranchiana” dell’areatipo (carraro, 1996; fig. 4). 4. diacronicità delle unità stratigrafiche ed episodi climatici e tettonici a completamento delle considerazioni sopra esposte e per analizzare i punti c) e d) dell’introduzione, occorre ricordare che in contesti geodinamici caratterizzati da mobilità tettonica (es. catena in sollevamento) fra i fattori che controllano il sistema sedimentario continentale, oltre al ruolo “dinamico” dei fattori esogeni ed endogeni va aggiunto quello “statico” fig. 1 tappe (da sinistra a destra) della costruzione di un’ipotetica successione stratigrafica costituita dalla composizione di “episodi” deposizionali ed erosionali. i numeri indicano i singoli “episodi” e la corrispondente “risposta” geologica (corpo sedimentario o superficie di erosione); t1, t2 … t7 gli intervalli di tempo. a, b e c superfici di erosione di rango da superiore a inferiore. nota: non c’è alcune relazione tra lo spessore dei corpi sedimentari ed i corrispondenti intervalli di tempo; la completa obliterazione dei corpi 3, 3a, 4 e 5 dovuta all’episodio erosionale 6, dimostra che, anche senza tener conto delle altre motivazioni indicate nel testo, non c’è diretta confrontabilità tra la successione stratigrafica conservata (1, 6 e 7) e la successione degli eventi (1…7); vedi fig. 2. chronological steps (from the left to the right) of the construction of an imaginary stratigraphic succession deriving from the composition of depositional and erosional episodes. numbers indicate the single episodes and their corresponding geological answer (sedimentary body or erosional surface); t1, t2,.... t7 the time spans. a, b and c: decreasing rank of erosional surfaces note: there is no relation between the thickness of the sedimentary bodies and the corresponding time spans; the complete obliteration of 3, 3a, 4 and 5 bodies due to erosional episode 6 demonstrates that, even without taking into account the others motivations mentioned in the text, there is no direct comparability between the stratigraphic succession preserved (1, 6 and 7) and the sequence of episodes (1.....7); see fig 2. fig. 2 possibile correlazione tra la successione stratigrafica finale di fig. 1 e la relativa successione di “episodi”. si noti la non esatta corrispondenza cronologica e la mancata rappresentazione di alcuni “episodi”. possible correlation between the final stratigraphic succession of fig. 1 and the related succession of episodes. note the not exact chronological correspondence and the lack of representation of some episodes evento estremo della durata di qualche ora oppure l’effetto cumulato di un episodio climatico di stabilità. ciò può dipendere in prima analisi dalle caratteristiche fisiche dei diversi ambienti di sedimentazione (es. fluviale, glaciale, lacustre, ecc.). anche la durata dei diversi “episodi” climatici che controllano la sedimentazione o l’erosione può essere molto diversa: si pensi alle variazioni a brevissimo, breve, medio e lungo periodo. gli studi sulla tettonica recente ed in atto stanno dimostrando che lo stesso vale per le deformazioni sin296 della diversa erodibilità delle formazioni rocciose via via esumate dall’erosione. quest’ultimo è responsabile della forte inerzia con cui il sistema risponde ai primi due gruppi di fattori (fig. 5). i tempi di reazione e di rilascio dei sistemi naturali successivi agli eventi che hanno introdotto la perturbazione possono essere molto diversi, così come i tempi di persistenza delle forme e dei depositi che li testimoniano. il geologo del quaternario si trova pertanto di fronte a sistemi naturali complessi nei quali i singoli fattori sono caratterizzati da velocità estremamente variabili (fig. 6): • le velocità con cui avvengono i cambiamenti climatici, • quelle con cui molto probabilmente avvengono anche le variazioni dell’attività geodinamica e, infine, • quelle con le quali si verifica l’esumazione di formazioni rocciose con diversa erodibilità. da ciò deriva la forte diacronicità (in genere purtroppo non verificabile) che può caratterizzare nel loro sviluppo complessivo la base ed il tetto di un’unità sedimentaria o una superficie di erosione in tutta la sua estensione. ad esempio la base dell’unità che rappresenta l’ultima massima espansione glaciale (lgm) in tutto lo sviluppo di una valle alpina ha una età molto diversa da valle verso monte. il divario cronologico tra l’età di una superficie nei vari punti della sua estensione può giungere fino ad essere di durata confrontabile con quella degli eventi climatici o tettonici che l’hanno determinata (un esempio in questo senso è fornito dal fatto che il numero di ordini di terrazzi che altro non sono che una successione di corpi sedimentari e di superfici di erosione presenti allo sbocco di una valle fluviale è diverso da quello presente in un’altra valle anche contigua). questa constatazione, del resto, non è altro che la trasposizione all’ambiente continentale e al quaternario di quanto riconosciuto per l’ambiente marino e per il pre-quaternario negli anni ’50, quando si è compreso che le unità sedimentarie che si riconoscono sul terreno sono unità litostratigrafiche e non hanno necessariamente una valenza cronologica. l’unica differenza, almeno apparente, sta nel fatto che le dimensioni degli episodi climatici o tettonici quaternari che si vogliono fig. 4 soft sediment deformations nei depositi “villafranchiani” (cava rdb, villafranca d’asti, asti). soft sediment deformations of the “villafranchian” deposits (rdb quarry, villafranca d’asti, asti). f. carraro & m. giardino fig. 3 deformazioni recenti del complesso fluviolacustre olocenico di st. vincent (cava zerbion, chatillon, aosta) (da carraro & alii, 1994). recent deformation of the st. vincent holocene fluviolacustrine complex (zerbion quarry, chatillon, aosta) (from carraro & alii, 1994). correlare con i vari termini della successione stratigrafica sono in assoluto minori di quelle degli episodi prequaternari, mentre il grado di diacronicità di una unità sedimentaria o di una superficie di erosione è indipendente dall’età. il grado di scansione che viene utilizzato nella cronologia del quaternario è però anch’esso molto più dettagliato per cui, se la diacronicità delle unità stratigrafiche è trascurabile nella stratigrafia del prequaternario non lo è invece in quella del quaternario. ne consegue la validità del punto d), cioè la non correlabilità corpo-episodio climatico o tettonico. 297 fig. 5 applicazione all’ambiente fluviale del concetto di “inerzia” nella risposta del sistema naturale alle sollecitazioni esterne (da bull, 1997). rt tempo di risposta = ra tempo di reazione + ra tempo di attenuazione. ps tempo di persistenza delle nuove condizioni di equilibrio. t ed e, condizioni di soglia e di equilibrio rispettivamente. application to the fluvial environment of the “inertia” concept in the response of the natural environment to the external stresses (from bull, 1997). rt , response time, is the sum of the reaction time, ra, and relaxation rime, ra. ps is the time of persistence of new equilibrium conditions, and t and e are threshold and equilibrium conditions, respectively. fig. 6 confronto fra velocità di diversi processi geologici esogeni ed endogeni (da summerfield 1991, modificato). comparison of rates of various endogenic and exogenic geomorphic precesses (from summerfield 1991, modified). considerazione sui criteri di correlazione ... 298 5. valore “assoluto” e buon grado di risoluzione degli elementi cronologici per quanto riguarda il reale significato delle datazioni numeriche (punto e), verranno prese in esame tre tipi di situazioni che posso rendere problematiche le correlazioni: • l’effettiva associazione dell’elemento che si data con l’“episodio” che si intende datare; • la possibile apertura del sistema chimico di riferimento per le datazioni geochimico-isotopiche; • il margine di errore nelle datazioni per effetto delle misure di laboratorio. il più importante è quello della effettiva associazione dell’elemento che si data con l’“episodio” che si intende datare. l’esempio che si cita di solito al riguardo è quello di un tronco fluitato ripreso da un deposito preesistente, la cui età non rispecchia quella del sedimento fluviale che lo contiene ma quella del deposito primario. ma accanto a questa si possono citare altre situazioni, ben più insidiose, nelle quali il divario di età può essere molto superiore. si prendano ad esempio i casi illustrati nelle figg. 7a e 7b. il disegno a esemplifica la situazione che può venirsi a creare, nel corso dell’evoluzione geologica superficiale (i singoli “episodi” della quale vengono indicati con una successione di numeri ordinali a partire dal substrato contrassegnato con 0) quando un suolo, sviluppatosi sul substrato nell’“episodio”, poniamo, n. 27 può essere ripreso da processi di colluvionamento durante l’“episodio”, poniamo, n. 104, ed i suoi prodotti colluviali, in molti casi assai difficilmente distinguibili dal suolo in posto, simulino l’età dell’elemento 27 per l’intercalazione 104. la stessa situazione può determinarsi nel caso di un deposito piroclastico depostosi sul substrato. tale circostanza è ancor più difficilmente riconoscibile nei casi (non infrequenti) in cui l’evoluzione geologica successiva ha portato ad un’inversione del rilievo (come rappresentato nella figura b) con la totale obliterazione dell’elemento 27. e’ da sottolineare che la verifica della effettiva associazione dell’elemento che si data con l’“episodio” che si intende datare non è di competenza del geocronologo ma dell’autore del prelievo, cioè del geologo di campagna. il secondo tipo di condizionamento è quello, che tutti hanno ben presente, dell’apertura del sistema chimico: ricordiamo a titolo di esempio la perdita di ar nelle datazioni k/ar oppure la presenza di th detritico che falsa i risultati delle datazioni degli speleotemi o di corallari con il metodo u/th. il terzo condizionamento è quello, inevitabile, del margine di errore delle misure di laboratorio. a questo proposito, in fig. 8 vengono richiamati i risultati di un test di affidabilità delle datazioni con il metodo del 14c, effettuato da alcuni tra i principali laboratori di geochimica isotopica del mondo. dai risultati di questo check, sponsorizzato dall'iaea, finalizzato alla valutazione dello stato dell'arte della misura della radioattività 14c e, di conseguenza, dei dati di cronologia radiometrica che da questa derivano, è emerso che gli errori (presupposto che il campione fosse ideale, totalmente rappresentativo dell’“episodio” che si voleva datare) sono derivati dalle seguenti operazioni previste per l'ottenimento del dato cronologico: fig. 7 situazione che può derivare dalla rielaborazione colluviale di un livello databile, in grado di falsare l’interpretazione stratigrafica. a e b rappresentano due differenti casi, nel secondo dei quali è intervenuto un fenomeno di inversione del rilievo. situation eventually derived from the colluvial reworking of a datable layer, able to alter the stratigraphic interpretation. a and b are two different cases, the second one being the effect of a relief inversion. f. carraro & m. giardino a) procedimenti chimici preliminari (tipo, modalità, grado di completezza degli stessi); b) processo di conversione del campione nel composto chimico scelto per eseguire la misura della radioattività 14c; c) misura della radioattività 14c. il test al quale si riferiscono i risultati prevedeva una valutazione complessiva, quindi le incertezze relative ai punti a), b) e c). inoltre, poiché nelle misure sperimentali ha anche importanza la riproducibilità (un dato campione deve fornire la stessa età se rimisurato più volte), il campione oggetto dei due check era unico ed è risultato avere circa 5.000 anni b.p. questo è stato fornito a circa 70 laboratori nel mondo, inclusi quelli più prestigiosi; di questi solo una trentina eseguirono e quindi trasmisero i risultati delle misure. osservando i risultati, si nota che il numero dei laboratori accomunati dalla stessa dispersione nelle due prove è variabile. l’unico dato con una dispersione di –500 anni è imputabile a un errore, mentre gli altri possono considerarsi “fisiologici”. 299 fig. 8 rappresentazione grafica dei risultati di un test di affidabilità sulle datazioni al radiocarbonio (dati iaea). la dispersione tra -6 e +6% nei risultati delle datazioni di laboratorio è da considerarsi “fisiologica”. il valore di -10% è imputabile ad errore. graphical representation of a reliability test of radiocarbon datings (iaea data). the data dispersion between –6 and +6 has to be considered “physiological”. the –10% value is due to an error. fig. 9 eta' geologica" di un'unita' litoo allostratigrafica. sulla base dei dati disponibili l'età dell'unità risulta compresa tra 470.000 e 150.000 anni b.p., quindi tra la parte media e la parte superiore del pleistocene medio. in base ai dati reali (non noti) l'età è invece compresa tra 650.000 e 112.000 anni b.p. e quindi si estende tra la parte inferiore del pleistocene medio ed il pleistocene superiore. geological age of a lithoor allostratigraphic unit. based on available data, the unit age fits into an age interval between 470.000 and 150.000 years b.p.. (middle middle pleistiocene – upper middle pleistocene). in fact, based on real data (unknown), the unit age fits between 650.000 ande 112.000 years b.p. (lower middle pleistocene – upper pleistocene). considerazione sui criteri di correlazione ... 6. l’età di un’ “unità stratigrafica l. s.”. considerazioni conclusive nei casi fortunati in cui si disponga di elementi di datazione, va però tenuto presente il possibile forte divario esistente tra l’intervallo di tempo definito dagli elementi di datazione disponibili e l’età effettiva dell’unità stratigrafica. naturalmente il divario tra età indicata dagli elementi disponibili e l’età reale esiste anche nelle datazioni del pre-quaternario ma in questi casi è in genere trascurabile dato il basso grado di scansione cronologica utilizzato. da tutto quanto esposto ci sembra risulti sufficientemente documentato che correlazioni basate su un basso numero di datazioni sono molto deboli e discutibili. nel tentare delle correlazioni appare perciò opportuno spingersi, solo in presenza di un numero significativo di elementi di datazione, unicamente al livello o ai livelli che contengono gli elementi stessi e non all’intera unità sedimentaria, meno che meno alla successione in cui questa è compresa. qualsiasi altro tentativo resterà tale e come tale è opportuno sia presentato in eventuali lavori di sintesi. lavoro pubblicato nell’ambito del progetto di ricerca cofin-miur 2002 “frane e clima”, coordinatore nazionale prof. m. soldati 7. lavori citati bull w. b. (1991) geomorphic responses to climatic change. 326 pp. oxford univ. press, new york. carraro f. (ed.) (1996) revisione del villafranchiano nell'area-tipo di villafranca d'asti. il quaternario, vol. 9, fasc. 1, 5-120, 66 ff., 2 tt. (1 carta geol. 1:20.000). carraro f., ghibaudo g., giardino m. & perotto a. (1994) intense deformazioni in depositi fluviolacustri olocenici nella media valle d'aosta. atti ticinesi sc. terra, ser. spec., vol. 1, pp. 123-136, 6 ff, 1994. carraro f. & lucchesi s. (in stampa) application of integrated allostratigraphy in the geological survey of the central piedmontese plain. in: pasquarè g. & venturini c.: geological mapping in italy, selca, firenze. giardino m. & polino r. (1997) le deformazioni di versante dell’alta valle di susa in relazione con l’evoluzione tettonica recente. dati preliminari. il quaternario, 10 (2): 31-38. summerfield m. a. (1991) global geomorphology: an introduction to the study of landforms. 537 pp. longman scientific and technical, essex. 300 ms. ricevuto il 20 luglio 2004 testo definitivo ricevuto il 30 novembre 2004 ms. received: july 20, 2004 final text received: november 30, 2004 f. carraro & m. giardino imp.girotti pplliioo--pplleeiissttoocceennee ssttrraattiiggrraapphhyy aanndd rreellaattiioonnss bbeettwweeeenn mmaarriinnee aanndd nnoonn--mmaarriinnee ssuucccceessssiioonnss iinn tthhee mmiiddddllee vvaalllleeyy ooff tthhee ttiibbeerr rriivveerr ((llaattiiuumm,, uummbbrriiaa)) ooddooaarrddoo ggiirroottttii11--22 && mmaarrccoo mmaanncciinnii11 1 dipartimento di scienze della terra, università degli studi di roma “la sapienza” piazzale aldo moro 5, 00185 roma odoardo.girotti@uniroma1.it; marco.mancini@uniroma1.it 2 cnr igag co dipartimento di scienze della terra, università degli studi di roma “la sapienza”. abstract the middle valley of the tiber river (mvt) corresponds to the “paglia-tevere graben”, a “neoautochthonous” basin developed since the latest early pliocene. the basin is in part linked with the intrapenninic tiberino and rieti basins to the east, and with the roman basin to the south. the filling is mostly made up of plio-pleistocene marine deposits, unconformably overlaying the meso-cenozoic substratum. two outcropping 3rd order depositional sequences have been recognised: 1) the older is composed of lower pliocene-earliest upper pliocene shelfal clays and sands (g. puncticulata and g. aemiliana chronozones) and rarer continental deposits; 2) the younger is late gelasian-santernian in age (g. inflata and g. cariacoensis-b. elegans marginata chronozones) and mostly corresponds to the “chiani-tevere formation”, composed of neritic clayey-sandy sediments interfingered with fluvial-deltaic gravelly-sandy deposits. the correlation between marine and non-marine deposits is based both on physical-stratigraphic observations and data (lithostratigraphy, facies analysis, sequence stratigraphy) and on their integration with biostratigraphic (foraminifera) and magnetostratigraphic data and with the numerical values of the 87sr/86sr ratio measured on mollusc shells, for the marine deposits, and with biochronological data (freshand brackish-water molluscs and ostracods, mammals) for the non-marine and transitional deposits. as for the younger successions from the latest early pleistocene to holocene, which are characterised by travertines and gravelly fluvial terraced deposits, the correlation with the marine successions of the roman basin is indirect and mostly based on biochronology and on relations between sedimentary and volcanic units. riassunto la media valle del fiume tevere (mvt) tra orvieto e fiano rappresenta un’area ideale per lo studio delle correlazioni tra depositi marini e continentali plio-pleistocenici. infatti essa corrisponde al “bacino del paglia-tevere”, a prevalente sedimentazione marina, parzialmente contiguo ad est ai bacini intrappenninici di rieti e tiberino e al bacino romano a sud. viene intodotto un nuovo schema stratigrafico, che aggiorna il precedente di ambrosetti et al. (1987) e pone in evidenza la presenza di cicli sedimentari di iii e iv ordine controllati dall’evoluzione tettonico-regionale tramite fasi di subsidenza e di sollevamento. la correlabilità tra bacini si basa su: 1) dati stratigrafico-fisici ottenuti mediante rilevamenti litostratigrafici e analisi di facies; 2) biostratigrafia a foraminiferi; 3) biocronologia a mammiferi e molluschi continentali; 4) magnetostratigrafia delle successioni marine e datazioni ar/ar e k/ar di unità vulcaniche; 5) nuovi dati stratigrafico-isotopici ottenuti mediante misure del rapporto 87sr/86sr su gusci di molluschi e idrozoi. la fase di subsidenza è caratterizzata da due cicli sedimentari marino-continentali di iii ordine. il primo ciclo (tardo zancleanogelasiano iniziale) è composto dai depositi terrigeni marini delle “unità di fabro”, “formazione di tenaglie-fosso san martino” e “unità di città della pieve”, cui localmente si intercalano sedimenti fluvio-lacustri. il secondo ciclo (tardo gelasiano-santerniano) è caratterizzato dalla eteropia tra i depositi marini di piattaforma e transizionali della “formazione del chiani-tevere” e i depositi fluviali della “formazione di santa maria di ciciliano” e della “formazione di poggio mirteto”. in particolare all’interno della formazione marina, sono stati riconosciuti tre grandi episodi progradazionali intercalati a fasi trasgressive ed evidenziati dai sedimenti ghiaiosi deltizi dei “membri di civitella san paolo”, “torrita tiberina”, “vasanello”. il primo episodio progradazionale ricade al passaggio gelasiano-santerniano, mentre i successivi sono di età santerniana. la fase regionale di sollevamento (emiliano-olocene) è caratterizzata dai depositi misti carbonatico-terrigeni della “unità di giove” (pleistocene inferiore pp.), da vulcaniti, e dai depositi terrazzati fluviali ghiaioso-sabbiosi delle “unità di civita castellana” (pleistocene inferiore pp.-pleistocene medio pp.), “graffignano” (pleistocene medio), “rio fratta” (tardo pleistocene medio) e “sipicciano”(pleistocene superiore). sulla base dei dati di terreno (biocronologia, rapporti con unità vulcaniche) e di interpretazioni paleogeografiche si ipotizzano correlazioni tra le unità continentali della mvt e le unità marino-transizionali dell’area romana, per il tardo pleistocene inferiore e l’inizio del pleistocene medio. keywords: late pliocene, early pleistocene, latium, umbria, stratigraphy, paleogeography, sr isotope stratigraphy. parole chiave: pliocene superiore, pleistocene inferiore, lazio, umbria, stratigrafia, paleogeografia, stratigrafia isotopica dello sr il quaternario italian journal of quaternary sciences 1166(1bis), 2003, 89-106 11.. iinnttrroodduuccttiioonn the middle valley of the tiber river (mvt) represents a good example of how to correlate marine with non-marine successions, using both direct field observations and analytical techniques like facies analysis, paleontologic and isotope-stratigraphic analyses and their integration, for chronologic and paleoevironmental purposes. the mvt is located at the border between latium and umbria and widens up to 60 km, between the orvieto and fiano towns (fig. 1). structurally it corresponds to the “paglia-tevere graben” (funiciello et al., 1981), a nnw-sse trending extensional basin developed since the late early pliocene, in concomitance with the globorotalia puncticulata chronozone (barberi et al., 90 o. girotti & m. mancini fig. 1 geological map of the mvt. legend: a) rreecceenntt aalllluuvviiaall ddeeppoossiittss (holocene). b) ssiippiicccciiaannoo uunniitt: iv order fluvial terrace of the tiber river (late pleistocene). c) rriioo ffrraattttaa uunniitt:: iii order fluvial terrace (middle pleistocene). d) ggrraaffffiiggnnaannoo uunniitt: ii order fluvial terrace (middle pleistocene). e) vvoollccaanniicc aanndd vvoollccaannoo--sseeddiimmeennttaarryy ssuucccceessssiioonnss ooff tthhee 22nndd vvoollccaanniicc pphhaassee (middle pleistocene). f) cciivviittaa ccaasstteellllaannaa uunniitt:: i order fluvial terrace (early-middle pleistocene). g) ppyyrrooccllaassttiitteess aanndd llaavvaass ooff tthhee 11sstt vvoollccaanniicc pphhaassee (early pleistocene). h) ggiioovvee aanndd aaccqquuaassppaarrttaa ffoorrmmaattiioonnss: travertines (early pleistocene). i) cchhiiaannii--tteevveerree ffoorrmmaattiioonn: marine, fine-grained terrigenous deposits (late pliocene-early pleistocene). j) cchhiiaannii--tteevveerree ffoorrmmaattiioonn: transitional, coarse-grained terrigenous (cciivviitteellllaa ss.. ppaaoolloo,, ttoorrrriittaa ttiibbeerriinnaa and vvaassaanneelllloo mmeemmbbeerrss) and carbonatic deposits (late pliocene-early pleistocene). k) ppooggggiioo mmiirrtteettoo ffoorrmmaattiioonn: fluvial deposits (late pliocene-early pleistocene). l) iinnttrraammoonnttaannee llaaccuussttrriinnee aanndd aalllluuvviiaall ddeeppoossiittss (middle pliocene-early pleistocene). m) tteennaagglliiee--ffoossssoo ss.. mmaarrttiinnoo ffoorrmmaattiioonn: marine deposits (middle-late pliocene). n) ccaarrbboonnaattiicc aanndd ssiilliicciiccllaassttiicc ssuucccceess-ssiioonnss (trias-miocene). o) normal fault. p) thrust. q) stratigraphic log. 1994). it is bordered to the east by the mt pegliaamerini-narni-sabini-lucretili mts ridge, where triassic to miocene marine, carbonatic and siliciclastic successions crop out. the western borders of the basin are the castell’azzara-mt razzano ridge (barberi et al., 1994), almost totally overlain by the quaternary volcanites of the vulsini, cimini and sabatini mts volcanic districts, and the mt soratte horst. the basin is prevalently filled with plio-pleistocene marine terrigenous deposits. however, coeval non-marine and transitional terrigenous and carbonatic deposits extensively crop out along the western margin of the mt peglia-lucretili mts ridge (ambrosetti et al., 1987; barberi et al., 1994; girotti & piccardi, 1994), while pleistocene volcano-sedimentary successions are well exposed west of the tiber river (fig. 1). the present paper represents an update on the information about the neogene-quaternary stratigraphy of the mvt, both derived from the re-examinations of previously collected and published data and from new geological mapping and stratigraphic, sedimentologic and paleontologic analyses (mancini, 2000; mancini et al., 2001). in particular this work deals with: 1) the introduction of a new stratigraphic scheme; 2) detailed analyses of the relationships among late pliocene-early pleistocene marine, transitional and non-marine deposits; 3) paleogeographic reconstructions of the mvt and surrounding areas during the late pliocene-earliest middle pleistocene. 22.. pprreevviioouuss wwoorrkkss the study of the relations between pliopleistocene marine and non-marine deposits in the umbria-latium region was a topic for geologists since the late xix century, with particular interest in the stratigraphic, paleontologic and geomorphic features (tuccimei 1888; 1889; 1891; 1895; clerici 1895; 1929). in fact the “villafranchiano” stage was introduced for the first time in central italy just in the mvt, near poggio mirteto (tuccimei, 1889), after the discovery of a rich mammalian and molluscan fauna characterising that period (1). the non-marine deposits bearing such an assemblage were considered pliocene in age and overlaying, with angular unconformity, “astian” marine deposits (tuccimei, 1888; 1895). on the other hand, clerici (1895) disproved the angular unconformity proposing the lateral continuity between the villafranchian and the marine deposits. the heteropic relations between non-marine and marine deposits were recurrently considered in order to understand the geology of the tiber river’s valley and its surrounding areas. in particular, discoveries of marine and transitional sediments within fluvial and lacustrine successions near terni (terrenzi, 1886) and todi (principi, 1922), based on malacological observations, should be mentioned. therefore, the possibility of correlating marine and non-marine deposits was later put in evidence by discoveries of fresh-water molluscs and mammals within marine and nearshore successions and of brackish-water assemblages into non-marine successions, in particular in the roman area (bonadonna, 1968; girotti, 1972) and in the south-western tiberino basin (ippolito 1947; girotti, 1967; conti & girotti, 1977; ambrosetti et al., 1987), which are laterally continuous to the mvt southward and eastward respectively. progress in the stratigraphical knowledge of the mvt, mainly due to micropaleontological studies (ambrosetti et al., 1987; buonasorte et al., 1991), led to the introduction of two marine sedimentary cycles (fig. 2): 1) the first cycle developed during the latest early pliocene and the earliest late pliocene, between the g. puncticulata and g. aemiliana zones. it includes the “argille di fabro”, the “sabbie a flabellipecten” and the “conglomerato di città della pieve” units (ambrosetti et al., 1987). 2) the second cycle is chronologically limited to the santernian and corresponds to the “argille sabbiose del chiani-tevere” unit (asct), which indicates marine and brackish-water environments, laterally continuous with the “complesso argilloso-sabbioso” unit 91plio-pleistocene stratigraphy ... (cas), of fluvial and lacustrine environment (ambrosetti et al., 1987). the two cycles are separated by an unconformity of regional importance known as the “fase erosiva dell’acquatraversa” (bonadonna, 1968) coinciding with the g. inflata zone. as a result of the new stratigraphic setting and mapping, most of the marine deposits, previously thought of pliocene age, are actually early pleistocene, while the heteropic relations among fully marine, transitional and non-marine units were detected only within the second sedimentary cycle (ambrosetti et al., 1987; piccardi, 1993). 33.. mmeetthhooddoollooggyy thirty surface stratigraphic sections (fig. 1) have been analysed using the standard methods of field geology and facies analysis (miall, 2000), examining in particular their lithologic, textural and paleontologic features. micropaleontologic data have been obtained by collecting 73 samples of pelite or sand (mancini, 2000), for qualitative analyses on micro-molluscs and forams, and have been added to the bibliographic data about the same topic (ambrosetti et al., 1987; carboni et al., 1993; piccardi, 1993; di bella, 1994; carboni & di bella, 1994; carboni & di bella, 1996; ciangherotti et al., 1998). each sample, having a 200 cm3 volume, was treated with a h2o and h2o2 solution, and washed through a 125 µm sieve. the >125 µm size fraction of the wash residue was considered for the collection and recognition of the microfauna; up to 300 specimens for sample were counted. the biostratigraphic scheme used is from cita (1975) and iaccarino (1985), while the chronostratigraphic scheme is based on sprovieri (1993) and cita & castradori (1995). twelve measures of the 87sr/86sr ratio on fragments of marine molluscs and hydrozoa have been carried out by prof. mario barbieri, at the “istituto di geologia ambientale e geoingegneria” (cnr-rome), for chronostratigraphic purposes; the analytical method is described in barbieri et al. (1998). several radiometric (arias et al., 1980; borghetti et al., 1981; sollevanti, 1983; laurenzi & villa, 1987; cioni et al., 1993; barberi et al., 1994; perini et al., 1997) and magnetostratigraphic (florindo & sagnotti, 1995; borzi et al., 1998) data were used to directly date several volcanic and sedimentary units. 44.. ssttaattiiggrraapphhiicc sseettttiinngg ooff tthhee mmvvtt the sedimentary units decribed below are of the lithostratigraphic and of the ubsu type (salvador, 1994). in part they have already been introduced, while the others are presented here for the first time; in both cases they are going to be formalised. such units are separated on the basis of their ages, also considering the sedimentary cyclicity previously introduced (ambrosetti et al., 1987; bossio et al., 1998) and the regional geological evolution with reference to the latial volcanism and its cyclicity (barberi et al., 1994; mancini, 2000). consequently, these units are grouped into: latest early pliocene-earliest late pliocene units, latest late 92 o. girotti & m. mancini f ig . 2 s tr a tig ra p h ic s ch e m e o f th e m v t 93 pliocene-earliest early pleistocene units, middle early pleistocene-earliest middle pleistocene units, middle pleistocene-holocene units. 44..11.. llaatteesstt eeaarrllyy pplliioocceennee--eeaarrlliieesstt llaattee pplliioocceennee uunniittss these units crop out along the western margin of the mt peglia and of the northern amerini mts, south of orvieto, and near the mt soratte (fig. 1). they constitute the first mvt “neoautochthonous” sedimentary cycle and are: the fabro formation, the tenaglie-fosso san martino formation and the città della pieve unit. 44..11..11.. tthhee ffaabbrroo ffoorrmmaattiioonn the fabro formation, already known as argille di fabro (ambrosetti et al., 1987), crops out in the northernmost mvt along the paglia river banks. it is composed of blue-grey, marine, sandy clays, mostly massive or tabular bedded. the strata, which are tectonically tilted, gently dip toward east, 8-10°. the thickness of the formation is up to 100 metres. the malacologic content, which was fully detailed by malatesta (1974), indicates the neritic circalittoral stage. the presence of g. puncticulata and g. aemiliana is indicative of the early-middle pliocene age. non-marine and presumably transitional deposits were recently discovered near orvieto, in the camorena site (barberi et al., 1994), and near fabro (petronio et al., in press). these deposits are interlayered with the marine ones, at the base of the g. aemiliana zone (about 3.0 ma). the malacologic content suggests that such sediments are of fluvial and lacustrine environments and of early villafranchian age (2) (ciangherotti et al., 1998; petronio et al., in press). 44..11..22.. tthhee tteennaagglliiee--ffoossssoo ssaann mmaarrttiinnoo ffoorrmmaattiioonn the tenaglie-fosso san martino formation crops out in the mt peglia and northern amerini mts areas, where it corresponds to the sabbie a flabellipecten formation (ambrosetti et al., 1987), and west of mt soratte. it unconformably overlays the meso-cenozoic substratum, vertically continuous above the fabro formation. its maximum thickness is up to 200 m. the formation is commonly composed of massive or tabular stratified sands, in some cases well cemented by calcium carbonate. structures like hummocky and swaley cross stratification and gravelly lenses, few metres thick, are common. in the mt soratte area the sands laterally pass to well cemented, oligomittic, poorly sorted conglomerates and breccias, almost exclusively calcareous. the clast size ranges from a few centimetres up to 1 metre. the paleontologic content is very rich and composed of pecten (flabellipecten) flabelliformis, chlamys (gigantopecten) latissima, terebratula ampulla, ostrea spp., balanidae, bryozoa and rhodophyceae. the foraminifer assemblage is characterised by g. aemiliana, bulimina marginata and amphistegina spp., typical of the late middle pliocene and of the earliest late pliocene. the sedimentologic and paleontologic data indicate the shoreface and the offshore-shoreface transition environments. 44..11..33.. tthhee cciittttàà ddeellllaa ppiieevvee uunniitt this unit, already known as conglomerato di città della pieve (ambrosetti et al., 1987), crops out in few sites of the northern mvt. it is composed of well cemented cobblestones, up to 10 metres thick, conformably overlaying the tenaglie-fosso san martino formation. these rudites are interpreted as gravelly beach deposits (ambrosetti et al., 1987). 44..22.. tthhee llaatteesstt llaattee pplliioocceennee--eeaarrlliieesstt eeaarrllyy pplleeiissttoo--cceennee uunniittss such units, which form the second “neoautochthonous” marine and non-marine cycle, widely crop out in the entire mvt. the units described below are: the chiani-tevere formation, the poggio mirteto formation and the santa maria di ciciliano formation. 44..22..11.. tthhee cchhiiaannii--tteevveerree ffoorrmmaattiioonn the chiani-tevere formation, which corresponds to the argille sabbiose del chiani-tevere (ambrosetti et al., 1987), is composed of marine, transitional and more limited non-marine deposits. it unconformably overlays the tenaglie-fosso san martino formation and the meso-cenozoic substratum (fig. 3). its maximum thickness in outcrop is up to 350 m, but as the base rarely crops out the formation may be thicker. the marine deposits are composed of blue-grey sandy clays, commonly massive or planar bedded, vertically passing to massive sandy silts and fine silty sands, where structures like hummocky cross stratification and turbiditic beds are common. such fine lithofacies vertically pass to coarse grained sands, with frequent amalgamated hummocky and swaley cross stratifications and trace fossils like scolicia and thalassinoides. strata are commonly sub-horizontal. the entire succession of lithofacies described above, which is well exposed in the northern mvt, indicates a regressive trend from inner shelf to shoreface deposits (mancini, 2000). east of mt soratte a few metres thick, bioclastic calcarenitic level (fig. 4), almost totally composed of chaotically amalgamated nearshore molluscs, echinids and corals, and well rounded pebbles, covers the underlaying coastal and fluvial deposits (see the discussion below). it is interpreted as a transgressive lag deposit, which is laterally continuous to the cemented sands, very rich in forams, that crop out at vallericca (carboni et al., 1993) few km far from the mvt southward (fig. 4). still in the vallericca section, a several decimetres thick horizon of resedimented pyroclastites also crops out (arias et al., 1980) (fig. 4), which is placed within the b. marginata zone (carboni et al., 1993). this level is dated 2.1 ± 0.2 ma by fission track analyses on volcanic glass shards (arias et al., 1980), and 1.8 ± 0.3 ma by analyses on zircons (arias et al., 1990). furthermore, recent magneto-stratigraphic analyses (florindo & sagnotti, 1995; borzi et al. 1998), carried out several metres above and below the volcanoclastic level, suggest that the investigated section may be placed at the c2r.1r polarity subchron of the geomagnetic polarity time scale (cande & kent, 1992), between the reunion and olduvai subchrons. this horizon is the only dated layer and one of the lowermost outcropping beds of the formation. the microfauna is abundant and contains: bulimina marginata and globorotalia inflata, only found in the lower part of the formation (piccardi, 1993; carboni & di bella, 1996), and bulimina elegans marginata, bulimina etnea, cassidulina carinata, valvulinerina bradyana, bolivina alata, uvigerina peregrina, globigerina cariacoensis, globigerinoides tenellus, globigerina calabra, plio-pleistocene stratigraphy ... 94 o. girotti & m. mancini f ig . 3 – s tr a tig ra p h ic a n d s e d im e n to lo g ic r e la tio n sh ip s a m o n g p lio -p le is to ce n e m a ri n e , tr a n si tio n a l a n d n o n -m a ri n e d e p o si ts a lo n g t h e w e st e rn m a rg in o f th e a m e ri n i m ts . l e g e n d ( sy m b o ls a re th e s a m e a s in f ig u re s 4 a n d 5 ): 1 = t ra n si tio n o ff sh o re -s h o re fa ce s a n d y si lts a n d o ff sh o re c la ys ; 2 = u p p e r a n d lo w e r sh o re fa ce s a n d s; 3 = p ro g ra d in g b e a ch g ra ve ls ; 4 = b io cl a st ic c a lc a re n iti c le ve l; 5 = c e m e n te d c a rb o n a tic s a n d s; 6 = l a g o o n a l a n d d e lta -f ro n t sa n d y cl a ys ; 7 = t ra ve rt in e s; 8 = l a cu st ri n e a n d f lo o d p la in c la ys ; 9 = f lu vi a l cr o ss b e d d e d g ra ve ls ; 1 0 = f lu vi a l cr o ss b e d d e d sa n d s; 1 1 = l ig n ite ; 1 2 = p yr o cl a st ite s; 1 3 = m o llu sc s sa m p le d f o r is o to p ic a n a ly se s; 1 4 = s e ct io n i n ve st ig a te d f o r m a g n e to -s tr a tig ra p h ic a n a ly se s; 1 5 = l ith o p h a g a b o ri n g s; 1 6 = m a ri n e m o llu sc s; 1 7 = b ra ck is h w a te r m o llu sc s; 1 8 = f re sh w a te r m o llu sc s; 1 9 = la n d s n a ils ; 2 0 = v e rt e b ra te r e m a in s. 95plio-pleistocene stratigraphy ... fig. 4 stratigraphic and sedimentologic relationships among marine, transitional and fluvial deposits in the central and southern part of the mvt. (1) = data after arias et al. (1980); (2) = arias et al. (1990); (3) = florindo & sagnotti (1995). globigerina aff. calida calida (carboni et al., 1993; di bella, 1994; carboni & di bella, 1994; mancini, 2000). it indicates the late gelasian-santernian age, in concomitance with the g. inflata-g. cariacoensis and the b. marginata-b elegans marginata zones. the macrofauna is characterised by corbula (vericorbula) gibba, natica tigrina, archimediella spirata, amyclina semistriata, sinodia brocchii, panopaea glycimeris, venus (ventricoloidaea) multilamella, pinna tetragona, cladocora coespitosa (piccardi, 1993; mancini, 2000). the analysis of the 87sr/86sr ratio carried out on several fragments of molluscs and hydrozoa (mancini, 2000) provided numerical values between 0.709068 and 0.709083 (tab. 1), which correspond to 1.5 and 1.7 ma. the chiani-tevere formation’s transitional and non-marine deposits extensively crop out along the eastern sector of the basin and are represented by the lithofacies assemblages described below. 1) fine clayey sands of brackish-water environment. these deposits are widespread along the western margin of the amerini-narni mts and correspond to the “facies salmastra” of the “asct” (am-brosetti et al., 1987). they are mainly composed of tabular stratified sands, which are laterally continuous westward to marine pelitic sands, and to the sandy fluvial deposits of the santa ma-ria di ciciliano formation (see below) to the east. a rich brackish water fauna has been found: cera-stoderma glaucum, bittium deshayesi, potamides tricinctus, thericium vulgatum, anadara darwini, trunculariopsis truncula conglobata, ammonia tepida. such deposits may be considered of the delta front environment (mancini, 2000). 2) travertines and c a l c a r e o u s silts. these n o n m a r i n e deposits crop out near the top of the formation and c o m m o n l y overlay the carbonatic substratum. they constitute tabular or lenticular bodies, few metres to several decametres thick (fig. 3), that are alternated with the brackish-water clayey sands. these lithofacies are rich in l a t e villafranchian fresh water molluscs and pulmonates like m e l a n o p s i s a f f i n i s , t h e o d o x u s g r o y a n u s , viviparus belluccii, emmericia umbra, neumayria priscillae, bithynia tentaculata, b. leachi, micromelania (goniochilus) zitteli, prososthenia meneghiniana, valvata cristata. 3) cross bedded coarse grained sands alternated with clinostratified gravels. they are coarsening-up alternances of sands and gravels interpreted as parasequences, marked at the base by a flooding surface. each parasequence is generally 2 to 10 metres thick. the lower sands are cross bedded and of the shoreface environment; they vertically and landward pass to clinostratified, westward prograding gravels, overlain by planar bedded gravels of the beachface environment (massari & parea, 1988). rarely at the top, thin horizons of massive clay bearing brackish water molluscs have been found. the gravels are commonly well sorted, rich in sandy matrix and composed of well rounded calcareous, cherty and arenaceous cobbles and pebbles; in many cases the clasts are perforated by lithophaga. balanids, anomia ephippium, and ostrea spp. are the most frequent fossils. three, very thick (50 to 100 metres), gravelly-sandy bodies, composed of several vertically stacked parasequences, crop out in the orte-amelia area and east of mt soratte. each of them represents a set of parasequences that interfingers with the nearshore marine deposits to the west and with fluvial deposits to the east. they correspond to the civitella san paolo member, the torrita tiberina member and the vasanello member (figs. 2, 4). 4) cross bedded talus. these deposits crop out at the 96 o. girotti & m. mancini tab. 1 top of the formation in several sites along the western margin of the amerini-lucretili mts, where they ovelay the mesozoic substratum and are in part covered by nearshore sands. this lithofacies is composed of poorly sorted rudites, rich in sandy and clayey matrix, and subangular clasts. the depositional architecture is characterised by alternated channelized and tabular bodies, seaward interfingering with the marine and transitional sands. the total thickness ranges between 50 and 80 metres. such deposits are interpreted as fan-delta deposits (girotti & piccardi, 1994; mancini et al., 2001). 5) breccias and conglomerates with abundant sandyclayey matrix. they are poorly sorted rudites, with subangular clasts commonly borrowed by lithophaga. such rudites crop out in many sites of the amerini-lucretili mts western margin, directly onlapping the meso-cenozoic substratum, and laterally continuous seaward to shoreface sands. they are interpreted as transgressive beach deposits and cliff breccias (girotti & piccardi, 1994). 44..22..22.. tthhee ppooggggiioo mmiirrtteettoo ffoorrmmaattiioonn the poggio mirteto formation is heteropic to the chiani-tevere formation’s transitional deposits. it crops out in the south-eastern mvt along the western margin of the sabini mts and in the lower farfa river valley, areas historically known as valli sabine (tuccimei, 1889). the formation is up to 300 m thick and is composed of cross bedded, well sorted gravels, alternated with lenses of trough cross stratified silty sands. at a large scale the gravels and sands are arranged into multistorey-multilateral channel-bodies and are interpreted as fluvial deposits filling active channels. they are also interbedded with tabular bodies of massive or thinly laminated clays, the thickness of which ranges between 1 and 20 m. the clays, which commonly contain lignite, may be interpreted as fluvial-overbank or lacustrine deposits. such fine sediments are rich in fresh water molluscs like m. affinis, t. groyanus, viviparus ampullaceus, prososthenia etrusca, p. meneghiniana, negulus villafranchianus, e. umbra, m. (g.) zitteli, belgrandia sp. (ciangherotti et al., 1998; mancini, 2000; petronio et al., in press); in several cases sandy and clayey horizons that bear brackish water molluscs have been found (see logs 28 and 29 in fig. 4). vertebrate fossils are rarer: few remains of equus stenonis were discovered at filacciano (di bella, 1995) (fig. 4), bocchignano and castel s. pietro (tuccimei, 1891, 1893), and bones of anancus arvernensis and stephanorinus etruscus at castel s. pietro (tuccimei, 1891; petronio et al., in press). the malacologic and mammal content indicates the olivola-tasso faunal units (ciangherotti et al., 1998; petronio et al., in press). 44..22..33.. ssaannttaa mmaarriiaa ddii cciicciilliiaannoo ffoorrmmaattiioonn the santa maria di ciciliano formation (basilici, 1993) crops out very limitedly in the amelia-narni area, where the mvt basin is directly linked with the southwestern branch of the tiberino basin. this formation is composed of cross bedded silty sands, that laterally pass to the transitional sands of the chiani-tevere formation. more detailed data are dealt with in ambrosetti et al. (1995). 44..33.. tthhee mmiiddddllee eeaarrllyy pplleeiissttoocceennee ––eeaarrlliieesstt mmiiddddllee pplleeiissttoocceennee uunniittss the units of this period are in the chronological order: the giove formation, the mt cimino volcanic and volcano-sedimentary successions, the civita castellana unit. 44..33..11.. tthhee ggiioovvee ffoorrmmaattiioonn the giove formation limitedly crops out along the western margin of the amerini mts, where it corresponds to the travertini antichi (ambrosetti et al., 1987). it unconformably overlays the chiani-tevere formation and laterally rests on the meso-cenozoic substratum. its base is generally subplanar, although it is locally incised for a few tens of metres into the chiani-tevere formation (see logs 4, 5 and 9, in fig. 3). its planar top surface gently dips toward sw from 350 to 280 metres a.s.l., providing a terraced appearence to the formation. the maximum thickness is 60 m. the lower part of the giove formation, which is 25 m thick, is composed of cross bedded, calcareous or quartz-bearing sands and gravels, commonly cemented by calcium carbonate and interspersed with lenses of travertines. such mixed carbonatic and silicilcastic facies vertically pass to thick layers of well cemented travertines or, more rarely (see log 11, fig. 3), to planar bedded calcareous silts bearing v. belluccii, m. affinis, t. groyanus, carychium minimum, e. umbra, hauffenia minuta, bithynia spp., lymnaea spp. (piccardi, 1993). at bandita di giove (see log 8, fig. 3) several remains of late villafranchian mammals have been found (petronio et al., in press): stephanorhinus etruscus, leptobos sp., elephantidae indet.. the sedimentologic and paleontologic data indicate that the giove formation deposited firstly in a fluvial environment of relatively high energy, and successively in little lakes and swamps dominated by carbonatic production. the probable age is middle early pleistocene. 44..33..22.. tthhee mmtt cciimmiinnoo vvoollccaanniicc aanndd vvoollccaannoo--sseeddiimmeennttaarryy ssuucccceessssiioonnss these deposits crop out in the western bank of the tiber river near orte and viterbo. they form a wide tabular body with undulate base placed at 200 to 220 metres a.s.l., about 150 m above the modern tiber river’s plain. they are mostly riodacitic pyroclastic flow deposits, locally interlayered with lavas and travertines. the maximum thickness exceedes 100 m. the activity of the mt cimino complex ranges between 1.35 and 0.95 ma (borghetti et al., 1981; sollevanti, 1983), and the most widespread formation is the “peperino” formation auct., a 1.30 ma old latitic ignimbrite (barberi et al., 1994). 44..33..33.. tthhee cciivviittaa ccaasstteellllaannaa uunniitt the civita castellana unit partly corresponds to the paleotiber gravels (alvarez 1972; 1973). it is an unconformity-bounded unit, mostly composed of fluvial gravels (mancini, 2000) overlaying the chiani-tevere formation; its unconformable base may be correlated to the “cassia erosional phase” (bonadonna, 1968; alvarez, 1972). no direct stratigraphic relationships with the giove formation and the mt cimino volcanites are evident. in the northern mvt as far as orte, this unit forms the highest fluvial terraced deposits, which represents 97plio-pleistocene stratigraphy ... the i order terrace of the tiber river. its tread gently decreases southward from 280 to 170 metres a.s.l., while the thickness is up to 80 m. south of orte and west of the mt soratte the civita castellana unit fills a deep incision carved into the chiani-tevere formation (fig. 5); there, the base is at 50 metres a.s.l. and the thickness reaches 120 m. the most frequent lithofacies are tabular and cross bedded gravels (gh, gt and gp facies sensu miall (1996)), while trough cross-bedded sands are rarer. the gravels, in general well rounded and lamellar or discoidal in shape, are mainly of calcareous nature, although arenaceous and siliceous clasts are also present. frequent imbricate structures indicate prevalent southward-directed flows. the sandy matrix is abundant and rich in quartz and muscovite, although the calcite may locally dominate. in some cases the sandy lenses are rich in biotite and sanidine, probably supplied after the erosion of the mt cimino volcanites; furthermore volcanic clasts belonging to the peperino formation were also found (brandi et al., 1970). the textural data and the depositional architecture, which shows multistorey-multilateral channel bodies, suggest that the civita castellana unit was deposited in a braidplain environment. the gravels and sands are rarely interbedded with few metres thick, tabular or lenticular, pelitic beds of the floodplain environment (fig. 5), and with travertines, lignites and buried paleosols. the pelitic levels are rich in fresh water molluscs like valvata piscinalis, bithynia spp., planorbis planorbis and more rarely m. affinis and t. groyanus (logs 18 and 21, fig. 5), characteristic of the early pleistocene. in the lowermost part of the formation few remains of bison cfr. b. degiulii, which indicates the farneta and pirro faunal units (latest late villafranchian) (gliozzi et al., 1997; di stefano et al., 1998), have been discovered (log 18, fig. 5). this unit is late early pleistocene-earliest middle pleistocene in age, as it is overlain by the initial products of the vulsini and sabatini mts volcanic complexes, placed at around 600-500 ka (barberi et al., 1994). 44..44.. tthhee mmiiddddllee pplleeiissttoocceennee--hhoolloocceennee uunniittss a staircase of fluvial terraced deposits borders the modern course of the tiber river. the graffignano unit (middle pleistocene), rio fratta unit (late middle pleistocene), sipicciano unit (late pleistocene) and the recent alluvial deposits (holocene) (figs 1 and 2) represent the ii, iii and iv order terraces. their respective treads decrease southward: 1) from 210 to 65 m a.s.l.; 2) from 150 to 40 m a.s.l.; 3) from 100 to 35 m a.s.l.; 4) 98 o. girotti & m. mancini fig. 5 stratigraphic relationships among pleistocene fluvial deposits in the western part of the mvt. g.u. = graffignano unit; r.f.u. = rio fratta unit. from 70 to 25 m a.s.l. all the terraced deposits are mostly composed of cross bedded gravels and sands of the braided river environment; overbank deposits, paleosols and travertines are less frequent. the volcanic and volcano-sedimentary successions of the vulsini mts, vico and sabatini mts are widely exposed along the western bank of the tiber, and are mainly composed of pyroclastites interbedded with lavas and travertines. the stratigraphic relationships between some dated volcanic formations and the terraced deposits provide a fairly precise chronological framework for the fluvial units (mancini, 2000) (fig. 2). the graffignano unit, indeed, is more recent than the tufo giallo della via tiberina formation, dated 550 ± 10 ka (cioni et al., 1993), but it precedes the lake vico lava formation (perini et al., 1997), with ages between 305 ± 9 e 258 ± 2 ka. the rio fratta unit is younger than the above mentioned lavas, but it is older than the tufo rosso a scorie nere vicano formation, 151 ± 3 ka old (laurenzi & villa, 1987). finally, the sipicciano unit is younger than the tufo rosso a scorie nere vicano formation. 55.. ddiissccuussssiioonn 55..11.. iinnffeerreenncceess oonn sseeddiimmeennttaarryy ccyycclliicciittyy dduurriinngg tthhee pplliioocceennee aanndd tthhee eeaarrlliieesstt eeaarrllyy pplleeiissttoocceennee.. the sedimentary units of the mvt are separated into two main groups. 1) the first group spans from late zanclean to santernian and is characterised by the preponderance of marine deposits on transitional and continental ones. it represents a subsidence-dominated stratigraphic domain as the basin fill occurred during phases of subsidence (ambrosetti et al., 1987; barberi et al., 1994; bossio et al., 1998). 2) the second group, which ranges from middle early pleistocene to holocene, is solely characterized by terraced continental deposits interlayered with volcanic and volcano-sedimentary successions, and indicates an uplift-dominated stratigraphic domain. the subsidence-dominated domain is composed of the two main marine-non-marine cycles described above (fig. 2): 1) the first cycle (late zanclean-early gelasian), which started at about 3.6 ma, corresponds to the i and ii sedimentary cycles described in barberi et al. (1994) and to the p2 and p3 units of bossio et al. (1998), spanning 1.2-1.3 ma; 2) the second cycle corresponds to the iii cycle of barberi et al. (1994) and to the unit q1 (bossio et al., 1998). it spans 0.65 ma (bossio et al., 1998) and probably began at 2.1 ma. the first cycle is up to 300 m thick, while the second cycle is 350 m thick. the time spans and thicknesses therefore suggest that the two cycles may be considered as iii order depositional sequences (vail et al., 1990). the acquatraversa erosional phase, which separates the two cycles, spans 0.2-0.3 ma (bossio et al., 1998). the related unconformable surface indicates a sea level drop probably due to local infra-gelasian tectonism, that caused the emersion and the eastward tilting of i cycle’s units, in the northern mvt and near mt soratte. the acquatraversa erosional phase may also be correlated to the global eustatic sea level fall that occurred at 2.4 ma, when a major event of cooling was recorded (haq et al., 1987; bossio et al., 1998). similarly, the older fluvial and lacustrine deposits interfingered with marine sediments at camorena (barberi et al., 1994) and fabro (fig. 2) may be interpreted as a sedimentary response to the global cooling event that occurred at about 3.0 ma (channel et al., 1992; bossio et al., 1998). in the central mvt, the acquatraversa unconformable surface may be present in the subsoil, below the lowermost outcropping levels of the ii sedimentary cycle. it may be possible that the unconformity laterally passes to a conformable surface as well. the few subsurface data from the mvt do not verify any hypotheses, as the drilled sediments only belong to the ii cycle (di bella, 1994; carboni & di bella, 1994). nevertheless, subsurface data from the bordering sabatini mts area, at bracciano (carboni & palagi, 1998)), and from vallericca (arias et al., 1990; carboni et al., 1993) in the lower tiber valley indicate the stratigraphic continuity from late zanclaean to santernian (figs 6 and 7). 55..22.. rreellaattiioonnss bbeettwweeeenn mmaarriinnee aanndd nnoonn--mmaarriinnee ssuucccceess-ssiioonnss aanndd llaattee ggeellaassiiaann--ssaanntteerrnniiaann ppaalleeooggeeooggrraapphhyy the mvt ii sedimentary cycle is characterized by the heteropic relations between the chiani-tevere and poggio mirteto formations, east of mt soratte, and between the chiani-tevere and santa maria di ciciliano formations near amelia. the main architectural feature is represented by three large clastic wedges interfingering with the chiani-tevere formation’s shelf deposits. the clastic wedges are composed of the gravelly-sandy beach deposits of the civitella san paolo, torrita tiberina and vasanello members, and of their laterally continuous fluvial deposits (figs 2-4). each wedge indicates a phase of basinward progradation of fluvial, deltaic and coastal sediments alternated with transgressive phases, that are evidenced by the shelf deposits (fig. 4). the first prograding wedge may have developed at the gelasian-santernian transition; this is suggested by the correlation with those marine successions where the plio-pleistocene boundary is present or inferred, like lugnano, orte scalo, vallericca (carboni et al. 1993; carboni & di bella 1994; borzi et al. 1998) (fig. 4). the younger wedges are santernian in age. such progradational phases are also evidenced by other transitional and continental lithofacies: 1) the “fine clayey sands of brackish water environment” and the “travertines and calcareous silts” are related to the ii and iii progradational episodes (fig. 3); 2) the fan deltas occurring at fosso marutana, camartana, montasola, poggio catino and marcellina (fig. 7) are only related to the iii episode. the transgressive phases are evidenced not only by the rapid deepenig of facies, but also by the progressive onlap of the “breccias and conglomerates with abundant matrix” above the substratum, and by alignements of lithophaga borings and notches (fig. 7a). such depositional and erosive elements indicate shortterm sea level stands that punctuated the transgressions. the latter also caused an eastward shifting of the transitional facies, that reached the southwestern tiberino basin, as it is indicated by the discovery of brackish water molluscs (fig. 7a). the paleogeographic thresholds linking the mvt and the tiberino basin were located east of amelia at the san pellegrino pass and, perhaps, at the forello gorge near todi and at configni in sabina (fig. 7); they are considered as outlets of ancient fluvial systems (ambrosetti et al., 1987; girotti & piccardi, 1994; d’agostino et al., 2001). the rieti basin 99plio-pleistocene stratigraphy ... 100 o. girotti & m. mancini f ig . 6 c o rr e la tio n b e tw e e n t h e m v t a n d s u rr o u n d in g s b a si n s (d a ta p a rt ly m o d ifi e d a ft e r b o n a d o n n a ( 1 9 6 8 ), b a si lic i ( 1 9 9 3 ), c a rb o n i e t a l. (1 9 9 3 ), b a rb e ri e t a l. (1 9 9 5 ), m a rr a e t a l. (1 9 9 5 ), m ill i (1 9 9 7 ), c a rb o n i & p a la g i ( 1 9 9 8 ), b e rg a m in e t a l. (2 0 0 0 ). 101plio-pleistocene stratigraphy ... f ig . 7 p a le o g e o g ra p h y o f th e l a tiu m -u m b ri a r e g io n d u ri n g t h e l a te g e la si a n -s a n te rn ia n : (a ) tr a n sg re ss iv e a n d ( b ) p ro g ra d a tio n a l p h a se s. l e g e n d : a ) ca rb o n a tic a n d s ili ci cl a st ic m e so -c e n o zo ic s u b st ra tu m , b ) a llu vi a l a n d l a cu st ri n e d e p o si ts , c) p lio -q u a te rn a ry n o n -m a ri n e d e p o si ts s u b je ct e d t o e ro si o n , d ) d e lta ic a n d c o a st a l d e p o si ts , e ) e m e rg e d m a ri n e d e p o si ts , f) t ra ve rt in e s, g ) vo lc a n ite s, h ) ve rt e b ra te r e m a in s, i ) b ra ck is h -w a te r m o llu sc s, j ) o lig o h a lin e o st ra co d s, k ) l ith o p h a g a b o ri n g s (w ith a lti tu d e a .s .l. ), l ) fa n -d e lta a n d a llu vi a llfa n , m ) d ir e ct io n o f a n ci e n t ri ve r, n ) d ir e ct io n o f d e lta ic p ro g ra d a tio n , o ) d ir e ct io n o f p yr o cl a st ic f lo w , p ) n o rm a l f a u lt, q ) st ri ke -s lip f a u lt, r ) m a in c ra te r. was probably affected indirectly by transgessions too, as it is evidenced by the presence of olighoaline ostracods in its northern sector, at fosso filundici and madonna della torricella (barberi et al., 1995; gliozzi & mazzini, 1998) (fig. 7a). it would be likely that the rieti basin was linked with the mvt basin through the terni sub-basin and/or the farfa valley (figs 1 and 7). on the other hand, the paleocoastline’s seaward shiftings, which occurred at the progradational phases, may be estimated at 12-15 km with respect to the western margin of mt peglia-lucretili mts ridge. such progradations are clearly evident in the vasanello-orteamelia and mt soratte-sabini mts areas in front of the deltaic systems of the paleo-nera and paleo-farfa rivers, that respectively drained the tiberino and rieti basins (fig. 7b). each progradation is related to periods of increased sedimentary supply coming down from the intramontane basins and their surrounding mountainous areas. this increment may be due to: 1) tectonics, that caused differential uplifts of the inner areas with respect to the subsiding marine basin. this twofold movement may have led to an increment of relief energy and consequent erosion in the emerged areas, and to an increase of accomodation space in the mvt basin. 2) climate changes, that may have been characterised by alternations between temperate and cold phases. in fact cooling episodes, if coupled with rainy periods and limited vegetation covers, may produce a great amount of eroded sediments and facilitate their transport. furthermore, they are in general associated with eustatic sea level falls. in the chiani-tevere formation the effects of climatically-induced sea level falls have been detected only within the fan-delta deposits (iii progradational episode). the related base level drop is estimated at 70 m, although neither the tectonic nor the eustatic component have been fully distinguished (girotti & piccardi, 1994). as for the older progradational episodes, no erosive or depositional elements linked to sea level falls, like incisions or downward shifts of coastal facies, have been observed. in fact, it seems likely that the progradational and transgressive deposits progressively filled the basin in concomitance with the subsidence throughout the entire late gelasian-santernian. therefore, negative eustatic movements have not been recorded by erosive surfaces, as their rates were of the same magnitude or slower than the subsidence rate. on the other hand, the sedimentologic and erosive effects of periodical sea level rises and transgressions are clearly evident, as it is discussed above. although the triggering mechanism that control the alternating progradational and transgressive phases is not clear at all, each couple of main progradation-transgression may suggest a iv order cyclicity within the main iii order cycle. 55..33.. sseeddiimmeennttaarryy aanndd ppaalleeooggeeooggrraapphhiicc eevvoolluuttiioonn dduurriinngg tthhee mmiiddddllee eeaarrllyy pplleeiissttoocceennee--eeaarrlliieesstt mmiiddddllee pplleeiissttoocceennee.. the regional uplift started at the earliest-middle early pleistocene between 1.5 and 1.3 ma (ambrosetti et al., 1987; cavinato et al., 1994) and continued throughout the rest of quaternary, determining the alternance of erosional and depositional phases in concomitance with climate changes. each sedimentary unit deposited during this period represents a cycle of degradationaggradation. in particular, the late middle pleistoceneholocene terraced units were cyclically deposited every 100 ka, with a recurrence due to global climatic changes related to variations of the orbital eccentricity (imbrie, 1985). as for the middle early pleistocene-earliest middle pleistocene units, chronological data are less precise, so making uncertain the linkage between the alternances of depositional and erosional phases and the 100 ka spanning cyclicity. however, all the sedimentary units may indicate a iv order cyclicity, although the inferred time span of the civita castellana unit is about 600 ka, a bit longer than a iv order cycle. the most evident paleogeographic change after the early uplift was the south-westward shifting of the coastline for more than 30 km away from the mt peglialucretili mts ridge. in this way the roman area was reached, where coastal facies developed (fig. 8a). during the emilian, the developing juvenile tiber river caused at first the incision of the just emerged gelasiansanternian sediments, and then the deposition of the giove formation in concomitance with the mt cimino volcanic activity. the ancient river flowed parallel to the axis of the paglia-tevere graben west of mt soratte (alvarez, 1972; 1973). the ancient tiber mouth may be represented by the transitional deposits of the “sabbie gialle di monte mario” (bonadonna, 1968); the latter crops out at monte mario in rome, covers santernian sediments and bears late villafranchian molluscs and vertebrates (girotti, 1972; caloi & palombo, 1988; petronio et al., in press) (figs. 6 and 8a). the tiber’s upper catchment was mainly affected by erosion, although local sedimentation persisted with the deposition of the lacustrine pelites of the “case strinati-madonna della torricella unit” in the northern rieti basin (cavinato et al., 2000), and of the travertines of the “acquasparta formation” in the southwestern tiberino basin (basilici, 1992) (figs. 6 and 8a). during the sicilian-earliest middle pleistocene, the coastline continued to migrate westward reaching the ponte galeria area, where fluvial-deltaic sediments were deposited (conato et al., 1980; milli, 1997; karner et al., 2000) (figs 6 and 8b). in the mvt the ongoing uplift caused a renewal of the fluvial incision the “cassia erosional phase” auct. – which may be estimated at more than 100 m (mancini, 2000). such an incision cuts the chiani-tevere and giove formations and caused the “cannibalization” of the oldest tiber river’s deposits. this downcutting also affected the mesocenozoic substratum at the forello and stifone gorges (fig. 8b), where the activity of local antiapennic-trending faults may have caused captures and deviations of the tiber and nera river courses (cattuto et al., 1997) (figs. 8a-b). the erosional phase was followed by the aggrading civita castellana unit. this unit may be correlated with the fluvial deposits outcropping at marcigliana in the lower tiber valley (basili, 1996), and with those filling the small ongoing “paleotiber graben” in the northern roman area (karner et al., 2001) (fig. 8 b). the correlation is suggested by both the lateral continuity between fluvial units, detected below the middle pleistocene sabatini mts volcanites (funiciello et al., 1994), and by biochronological data after the discove102 o. girotti & m. mancini 103plio-pleistocene stratigraphy ... f ig . 8 p a le o g e o g ra p h y o f th e l a tiu m -u m b ri a r e g io n d u ri n g : (a ) th e e m ili a n ; (b ) th e s ic ili a n -e a rl ie st m id d le p le is to ce n e . ries of vertebrates belonging to the farneta-pirro faunal units (late early pleistocene) in several sites as rio fratta, capena, redicicoli 1 (di stefano et al., 1998; petronio et al., in press). 66.. ccoonncclluussiioonnss the stratigraphic data and the consequent interpretation of the paleogeographic evolution of the mvt and surrounding basins delineate a late pliocene-earliest early pleistocene subsidence-dominated tectono-sedimentary phase and a middle early pleistocene-holocene uplift-dominated phase. the first phase provides direct chronostratigraphic elements, based on biostratigraphic, biochronologic, physical-, isotopicand magneto-stratigraphic analyses and observations which are of great relevance in correlating the interfingered marine, transitional and non-marine successions, widely outcropping at the borders of the mvt, tiberino and rieti basins. for the second phase, the new biochronologic data, the relations between fluvial and volcanic deposits and the inferred regional paleogeography provide indirect tools for the correlation between the fully non-marine mvt basin and the roman area, characterised by marine, transitional and fluvial successions, in particular for the emilian-early middle pleistocene interval. nnootteess:: (1) recent and exhaustive re-examinations of the ancient paleontologic findings in the valli sabine are published in kotsakis (1988), esu & girotti (1991), gliozzi et al. (1997), ciangherotti et al. (1998), petronio et al. (in press). (2) pareto (1865) introduced the villafranchian stage and attributed to it those non-marine sediments that were deposited above the pliocene marine successions as a consequence of a general withdrawal of the sea. he applied the term villafranchian to all the non-marine deposits of northand central-italy and considered it as quaternary in age. hürzeler (1967) recognized a pliocene age for the vertebrates of villafranca d’asti (the type locality of the stage) and azzaroli (1977) subdivided the villafranchian into early (middle pliocene), middle (late pliocene) and late (early pleistocene). most of the non-marine sediments ranging from middle pliocene to early pleistocene are actually mapped as villafranchian on the geologic map of italy. the succession of the type locality is middle pliocene. in recent times some doubt was expressed about the validity of the villafranchian as chronostratigraphic unit (carraro, 1996), whereas gliozzi et al. (1997) introduced and defined the villafranchian in the biochronological scale of the mammal ages. nevertheless, the pliopleistocene non-marine successions are so widespread in italy that, in our opinion, they need to be classified in an independent chronostratigraphical scale; in fact, an attribution to the marine one is rarely possible. therefore, we think that, in order to classify the huge amount of non-marine successions outcropping in italy, the villafranchian should not be abandoned and a formalization is to be hoped for. the lower boundaries of early and late villafranchian, at least, may be defined on sections at villafranca d’asti and in the upper valdarno respectively, where continuous sedimentation occured and litostratigraphy as well as palaeontological and magnetostratigraphical data are available. aacckknnoowwlleeddggeemmeennttss we would like to thank prof. mario barbieri for the isotopic analyses and dott. carlo bosi for the useful comments that have improved our manuscript. this research was supported by murst (60%) and by cnr igag. rreeffeerreenncceess alvarez w. 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(1987) chronology of the fluctuating sea levels since the triassic. science, 223355, 1156-1167. hürzeler j. (1967) nouvelles découvertes de mammifères dans les sédiments fluvio-lacustres de villafranca d’asti. colloques internat. c.n.r.s. 116633 “problèmes actuels de paléontologie (évolution del vertébrés)”. 633-636, paris, 6-11 juin 1966. imbrie j. (1985) a theoretical framework for the pleistocene ice ages. j. geol. soc. london, 114422,, 417-432. ippolito f. (1947) contributo alla conoscenza della malacofauna delle ligniti di colle dell’oro, presso terni. rend. acc. sc. fis. matemat. soc. scienze, lettere ed arti, 1155, 1-10. karner d.b., marra f., florindo f., & boschi e. (2001) pulsed uplift estimated from terrace elevations in the coast of rome: evidence for a new phase of volcanic activity? earth planet. sci. lett., 118888, 135-148. kotsakis t. (1988) biostratigraphy of plio-pleistocene arvicolids of italy. modern geology, 13, 163-175. laurenzi m.a. & villa i.m. 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(1988) progradational gravel beach sequences in a moderateto high-energy, microtidal environment. sedimentology, 3355, 881-913. mattias p.p. & ventriglia u. (1970) la regione vulcanica dei monti sabatini e cimini. mem. soc. geol. it., 99, 331-384. miall a.d. (1996) the geology of fluvial deposits: sedimentary facies, basin analysis and petroleum geology. springer verlag, berlin, 528 pp. miall a.d. (2000) principles of sedimentary basin analysis. 3 rd, updated and enlarged edition. springer verlag, berlin, 616 pp. milli s. (1997) depositional setting and high-frequency sequence stratigraphy of the middle-upper pleistocene to holocene deposits of the roman basin. geol. romana, 3333, 99-136. nappi g., renzulli a., santi p., & gillot p.y. (1995) geological evolution and geochronology of the vulsini volcanic district (central italy). boll. soc. geol. it., 111144, 599-613. nicoletti m. (1969) datazioni argon-potassio di alcune vulcaniti delle regioni vulcaniche cimina e vicana. per. mineral., 3388, 1-20. pareto m. (1865) note sur la subdivision que l’on pourrait établir dans les terrains de l’apennin septentrional. bull. soc. géol. fr., s.2, 2222, 210-277. perini g., conticelli s., & francalanci l. (1997) inferences of the volcanic history of the vico volcano, roman magmatic province, central italy: stratigraphical, petrographic and geochemical data. mineral. petrogr. acta, 4400, 67-93. petronio c., argenti p., caloi l., esu d., girotti o., & sardella r. (in press) updating villafranchian mollusc and mammal faunas of umbria and latium (central italy). geol. romana, 3366. piccardi e. (1993) il plio-pleistocene in sinistra del tevere dal lago di corbara a magliano in sabina. phd. diss., v cycle, università degli studi di roma "la sapienza", 210 pp, rome. principi p. (1922) alcune osservazioni sul quaternario dell’umbria centrale. atti dell’acc. naz. dei lincei, 3311, 56-59. salvador a. (1994) international stratigraphic guide, second edition. international union of geological sciences, trondeheim, and geological society of america, boulder, 214 pp. sollevanti f. (1983) geologic, volcanologic and tectonic setting of the vico-cimino area, italy. j. volcanol geotherm. res., 1177, 203-217. sprovieri r. (1993) pliocene-early pleistocene astronomically forced planktonic foraminifera abundance fluctuations and chronology of mediterranean plankton bio-events. riv. it. paleont. strat., 9999, 371-414. terrenzi g. (1886) il pliocene nei dintorni di narni. boll. soc. geol. it., 55, 321-336. tuccimei g. (1889) il villafranchiano nelle valli sabine e i suoi fossili caratteristici. boll. soc. geol. it., 88, 95-132. tuccimei g. (1891) alcuni mammiferi fossili delle provincie umbra e romana. mem. pontif. acc. nuovi lincei, 77, 89-152. tuccimei g. (1893) resti di arvicola nel pliocene lacustre della sabina. mem. pontif. acc. nuovi lincei, 99, 1-13. tuccimei g. (1895) il villafranchiano e l’astiano nella valle tra i cornicolani e i lucani. atti acc. pontif. naz. lincei, 1133, 1-30. vail p.r., audemard f., bowman s.a., eisner p.n., & perez-cruz g. (1990) the stratigraphic signatures of tectonics, eustasy and sedimentation. in “cycles and events in stratigraphy” ed. einsele g., ricken w., & seilacher a., 617-659, elsevier, amsterdam. 106 o. girotti & m. mancini imp. giraudi ii ddeeppoossiittii aalllluuvviioonnaallii oolloocceenniiccii ddii ccaammppoo iimmppeerraattoorree ((mmaassssiicccciioo ddeell ggrraann ssaassssoo –– aabbrruuzzzzoo)) ccaarrlloo ggiirraauuddii enea c.r. casaccia, c.p. 2400, 00100 roma a.d. riassunto il rilevamento geologico e geomorfologico di dettaglio eseguito sui sedimenti e sui terrazzi alluvionali di campo imperatore ha permesso di distinguere varie fasi di sedimentazione risalenti all’olocene. la scansione cronologica dell’attività alluvionale, ottenuta per mezzo di datazioni radiocarbonio su paleosuoli e sedimenti lacustri, dimostra come il trasporto solido nei corsi d’acqua sia avvenuto, seppure con diversa energia e con brevi fasi di interruzione, lungo gran parte dell’olocene. la fase di sedimentazione alluvionale olocenica che forma il primo terrazzo è avvenuta tra 12.100±100 bp (14.410÷13.770 cal bp) e un periodo successivo a 7060±70 bp (8120÷7910 cal bp) e precedente a 5420±80 bp (6400÷5950 cal bp). la sedimentazione del corpo alluvionale che forma il secondo terrazzo si è verificata tra 7060±70 bp (8120÷7910 cal bp) e 4070±70 bp ( 4830÷4410 cal bp). le alluvioni che formano il terzo terrazzo si sono deposte in un periodo compreso tra 4070±70 bp (4830÷4410 cal bp) e un momento successivo a 2130±50 bp (2190÷1990 cal bp) e precedente a 1410±40 bp (580÷689 ad). la sedimentazione delle alluvioni che formano il quarto terrazzo è avvenuta tra 1410±40 bp (580÷689 ad) ed un periodo più recente degli anni 1440÷1640 ad. il quinto terrazzo è stato formato dall’attività alluvionale recentissima. appare poi evidente la correlazione tra fasi di sedimentazione alluvionale individuate a campo imperatore e quelle riconosciute in altre località dell’appennino centrale e settentrionale; inoltre vi è una notevole coincidenza cronologica anche con le fasi di espansione del ghiacciaio del calderone e di alcuni ghiacciai alpini. abstract the campo imperatore holocene alluvial sediments (gran sasso massif – central italy) the detailed geological and geomorphological survey carried out on campo imperatore alluvial sediments and terraces enabled some holocene depositional phases to be recognised. the chronological framework has been obtained through radiocarbon datings on palaeosols and lacustrine sediments and shows that alluvial deposition took place, even if with some interruptions, during most of the holocene period. the deposition of the alluvial unit forming the first terrace took place between 12.100±100 bp (14.410÷13.770 cal bp) and a period more recent than 7060±70 bp (8120÷7910 cal bp) and older than 5420±80 bp (6400÷5950 cal bp). the second terrace alluvial sequence has been dated between 7060±70 bp (8120÷7910 cal bp) and 4070±70 bp ( 4830÷4410 cal bp). the deposition of the alluvial sediments forming the third terrace occurred between 4070±70 bp (4830÷4410 cal bp) and a period following 2130±50 bp (2190÷1990 cal bp) and preceding 1410±40 bp (580÷689 cal ad). the alluvial sediments forming the fourth terrace were deposited between 1410±40 bp (580÷689 cal ad) and a period following 1440÷1640 cal ad. the fifth terrace has been formed by very recent alluvial activity. thanks to the dating of the sediments one can observe a correlation between alluvial sedimentation at campo imperatore and in other central and northern apennine sites, and between the start of the alluvial phases and the advance of the calderone glaciers (on the gran sasso massif) and some alpine glaciers. the campo imperatore alluvial sedimentation appears strongly linked to the environmental impact produced by climatic oscillations, which affected both mediterranean and alpine areas, also affecting glaciers that cannot be changed by human activity. even if there is proof of fires that developed during prehistoric times, the data available show that the human impact was not able to produce any instability of the slopes and alluvial sedimentation phases not linked to the climatìc variations. the large, thick alluvial units outcropping at campo imperatore seem strongly linked also to the presence of cataclastic rocks on the slope surrounding the northern boundary of the plain; the gullies affecting the cataclasites were inactive only during short periods, when morphological stability prevailed and soils developed. the considerable detail regarding phases of sedimentation and pedogenesis preserved on the deposits (younger than the vi-vii centuries ad) forming the iv terrace seems due to the morphology of the site: the place is very flat and the water in the streams loses its energy, the sediments are mainly thin and between them lie gentle erosion surfaces. the same detail was not found in the older alluvial units lying in different places where the streams flowed with greater energy, the grain size was larger and erosional phases stronger. parole chiave: olocene, fasi alluvionali, variazioni climatiche, gran sasso, appennini. keywords: : holecene, alluvial phases, climatic variations, gran sasso massif, apennines. il quaternario italian journal of quaternary sciences 1166(2), 2003, 197-205 11.. iinnttrroodduuzziioonnee campo imperatore è un altopiano, lungo circa 18 km, largo da 1 a 4 km, che occupa il fondo di una conca chiusa tettonico-carsica posta a quote comprese tra 1850 e 1450 m. il drenaggio superficiale presente sull'altopiano termina negli inghiottitoi presenti nella porzione sud-orientale dell'area. tuttavia solo una piccola parte della rete di drenaggio appare attiva attualmente: si tratta di corsi d'acqua stagionali che defluiscono quasi esclusivamente nelle porzioni terminali delle valli poste ai margini della piana ove affiora il substrato. quando l'acqua raggiunge gli apici dei conoidi alluvionali viene infatti assorbita dai sedimenti grossolani. lo scorrimento di acqua negli alvei presenti sui conoidi avviene generalmente, insieme ad un notevole trasporto solido, in occasione di eventi piovosi eccezionali o nel corso di rapide fasi di scioglimento delle nevi dopo inverni molto 198 c. giraudi nevosi. tuttavia a giudicare dall'inerbimento della depressione che circonda gli inghiottitoi carsici e dall'assenza di alvei ben identificabili, si può arguire che attualmente l'acqua può arrivare agli inghiottitoi solo in rare occasioni, con bassa energia e senza carico solido. scopo del presente lavoro è lo studio e la datazione dei sedimenti alluvionali di campo imperatore per ottenere informazioni di carattere climatico-ambientale necessarie al completamento della ricostruzione dell'evoluzione paleoclimatica dell' area. i sedimenti alluvionali, rappresentati schematicamente sul foglio teramo della carta geologica d'italia a scala 1:100.000 (servizio geologico d'italia, 1963) e in demangeot (1965) sono stati in parte datati con metodi radiometrici per la prima volta da frezzotti & giraudi (1990), cartografati con maggiore dettaglio da frezzotti & giraudi (in ghisetti & vezzani, 1990) e descritti da giraudi (1994). ulteriori datazioni interessanti per l'inquadramento cronologico dei sedimenti alluvionali e fluvioglaciali di campo imperatore sono riportati in giraudi & frezzotti (1997) ed in giraudi (1998; 2001) nel presente lavoro verrà discusso l'inquadramento cronologico di alcuni depositi alluvionali utilizzando dati tratti dalla letteratura e nuove datazioni radiocarbonio. 22.. ii sseeddiimmeennttii aalllluuvviioonnaallii ddii ccaammppoo iimmppee-rraattoorree i sedimenti alluvionali occupano buona parte della porzione centrale ed orientale di campo imperatore, e formano alvei di corsi d'acqua stagionali, conoidi alluvionali e varie spianate terrazzate. gli estesi conoidi alluvionali, in particolare, rappresentano una componente assai evidente del paesaggio dell'altopiano. essi si trovano quasi esclusivamente al suo margine settentrionale: anche se spesso i conoidi si trovano allo sbocco di bacini idrografici poco estesi, hanno dimensioni rilevanti sicuramente a causa della presenza, sui versanti, di un'ampia fascia di cataclasiti facilmente erodibili. ghisetti & vezzani (1986;1990) e giraudi (1994) hanno evidenziato che le superfici dei conoidi si sono formate in varie fasi: nella porzione centro-orientale di campo imperatore si sarebbero formate in cinque fasi, mentre nella porzione occidentale, occupata da un esteso ghiacciaio nel corso dell'ultimo massimo glaciale, si sarebbero sviluppate in quattro fasi. i conoidi sono formati da varie parti incassate una nell'altra, caratterizzate da suoli con diverso grado di sviluppo e, in certi casi, da un diverso sviluppo della copertura vegetale. in base alle datazioni radiometriche riportate da frezzotti & giraudi (1990) e giraudi & frezzotti (1997) appare evidente che le più antiche superfici dei conoidi presenti nella porzione intermedia ed orientale di campo imperatore sono da attribuire all'ultimo massimo glaciale e quindi le fasi successive debbono essere avvenute nel tardiglaciale e nell’olocene. la ricostruzione dell’evoluzione morfologica dei conoidi alluvionali e delle fasi di sedimentazione postglaciali è stata resa possibile dal rilevamento geologicogeomorfologico di dettaglio, dal rinvenimento di parecchi affioramenti e dalla datazione di molti campioni di paleosuolo effettuata col metodo del 14c. di seguito vengono riportate le descrizioni dei siti e delle successioni alluvionali che hanno permesso di datare le fasi di sedimentazione oloceniche di campo imperatore. 22..11.. iill ccoonnooiiddee ddii vvaallllee ffoorrnnaaccaa allo sbocco della valle fornaca, (2a in fig. 1) tra i monti prena e camicia, è presente un conoide terrazzato, la superficie del quale si è formata in cinque diverse fasi: il corpo principale del conoide (ia fase) è costituito (frezzotti & giraudi, 1990; giraudi & frezzotti, 1997) da alternanze di ghiaie sabbiose e sabbie con intercalazione di suoli (fig. 2a) datati rispettivamente 31.500±550 bp e 17.840±200 bp; al tetto giacciono sedimenti fluvioglaciali trasportati dall’acqua di fusione di un piccolo apparato dell’ultimo massimo glaciale presente sul versante occidentale del m. camicia (giraudi & frezzotti, 1997). nella porzione sommitale della serie compare una fessura parzialmente riempita da carboni e ceneri, formatasi per scivolamento gravitativo di un blocco di sedimenti nel corso di una notevole fase di incisione che ha interessato il conoide. i carboni, datati con il metodo del 14c (giraudi,1999), hanno fornito una data di 5720±120 bp (6840÷6280 cal bp: calibrazione due sigma, come tutte le date successive). i conoidi della ii, iii, iv e v fase sono incassati rispettivamente di 2-4 m, 12, 14 e 15 m rispetto alla superficie della i fase. la destabilizzazione della parte sommitale della successione sedimentaria deve essere avvenuta mentre era in corso un’erosione successiva alla superficie del conoide della ii fase. la sedimentazione della iia fase del conoide è quindi precedente alla data di 5720±120 bp (6840÷6280 cal bp) mentre la sedimentazione dei conoidi delle fasi successive deve essere più recente. 22..22.. llee aalllluuvviioonnii ddii ffoonnttee ddeellllaa mmaacciinnaa presso fonte della macina (2b in fig. 1) affiora una serie di sedimenti alluvionali che formano tre distinti terrazzi. il primo terrazzo è formato (fig. 2b) da una serie di alluvioni prevalentemente ghiaioso sabbiose, nelle quali si intercalano suoli e livelli di alluvioni sabbiose limose, potenti circa 10 m; il tetto della serie è formato da sedimenti alluvionali, eteropici con i depositi fluvioglaciali che formano il conoide della i fase di valle fornaca precedentemente descritto; le alluvioni coprono un paleosuolo datato 21,450±250 bp (giraudi & frezzotti, 1997); al di sotto del paleosuolo i sedimenti si presentano con vario grado di cementazione e affiorano in banchi compatti. il secondo terrazzo, incassato di circa 8-10 m nel precedente, è formato da un deposito alluvionale ghiaioso-sabbioso alla base e sabbioso al tetto; tra le sabbie è intercalato un paleosuolo organico datato 5420±80 bp (bo-253; 6400÷5950 cal bp). il terzo terrazzo, incassato di circa 1 m nel precedente e sospeso di circa 1,5 m sul fondovalle attuale, è costituito prevalentemente da sabbie limose e limi e contiene, intercalato, un paleosuolo poco sviluppato. 22..33.. llee aalllluuvviioonnii ddii ppiiaannoo ddeellll’’oossppeeddaallee nella zona di piano dell’ospedale, ai margini della depressione di prati di cretarola ove sono presenti gli 199i depositi alluvionali olocenici di ... f ig .1 – c a rt a g e o lo g ic a s ch e m a tic a d i c a m p o i m p e ra to re e d e lle a re e c ir co st a n ti l e g e n d a : 1 se d im e n ti q u a te rn a ri ; 2 se d im e n ti te rr ig e n i c e n o zo ic i; 3 ro cc e c a rb o n a tic h e m e so -c e n o zo ic h e ; 4 ci rc h i g la ci a li; 5 m o re n e f ro n ta li d e ll’ u lti m o m a ss im o g la ci a le ; 6 m o re n e s ta d ia li; 7 g h ia cc ia io d e l c a ld e ro n e ; 8 in g h io tt ito i c a rs ic i; 9 sp a rt ia cq u e p ri n ci p a li; 1 0 u b ic a zi o n i d e lle s e zi o n i r a p p re se n ta te n e lle f ig . 2 e 3 . g e o lo g ic a l s ke tc h m a p o f c a m p o i m p e ra to re a n d n e ig h b o u ri n g a re a s. l e g e n d : 1 q u a te rn a ry s e d im e n ts ; 2 c e n o zo ic t e rr ig e n o u s se d im e n ts ; 3 m e so -c e n o zo ic c a rb o n a te r o ck s; 4 g la ci a l ci rq u e s; 5 l a st g la ci a l m a xi m u m f ro n ta l m o ra in e ; 6 st a d ia l m o ra in e s; 7 c a ld e ro n e g la ci e r; 8 p o n o rs ( sw a llo w -h o le s) ; 9 m a in d iv id e s; 1 0 si te o f th e s tr a tig ra p h ic s e ct io n r e p re se n te d in f ig . 2 a n d 3 . 200 fig. 2 – sezioni stratigrafiche schematiche dei sedimenti alluvionali studiati nella porzione orientale di campo imperatore. legenda fig. 2a: 1sedimenti alluvionali attuali e del conoide della v fase; 2sedimenti alluvionali del conoide della iv fase; 3sedimenti alluvionali del conoide della iii fase; 4sedimenti alluvionali del conoide della ii fase; 5sedimenti fluvioglaciali, 6sedimenti alluvionali; 7paleosuoli. legenda fig. 2b: 1sedimenti alluvionali attuali; 2alluvioni p r e v a l e n t e m e n t e sabbiose del terrazzo inferiore; 3alluvioni prevalentemente sabbiose del terrazzo intermedio; 4alluvioni ghiaiososabbiose del terrazzo intermedio; 5alluvioni ghiaiose del terrazzo più elevato; 6alluvioni sabbiose-ghiaiose; 7alluvioni sabbioso-limose; 8alluvioni ghiaioso-sabbiose cementate; 9paleosuoli. legenda fig. 2c: 1suolo attuale e paleosuolo intercalato ai sedimenti alluvionali; 2alluvioni limose; 3alluvioni p r e v a l e n t e m e n t e sabbiose; 4alluvioni sabbiso-ghiaiose. stratigraphic sketches through the alluvial sediments in eastern campo imperatore. legend fig. 2a: 1present and phase v alluvial fan sediments; 2alluvial fan sediments of phase iv; 3alluvial fan sediments of phase iii; 4alluvial fan sediments of phase ii; 5fluvioglacial sediments; 6alluvial sediments; 7palaeosols. legend fig. 2b: 1presentday alluvial sediments; 2alluvial sediments, mainly sandy, forming the lower terrace; 3alluvial sediments, mainly sandy, forming the intermediate terrace; 4gravelly-sandy alluvial sediments; 5gravelly-sandy alluvial sediments forming the higher terrace; 6gravelly-sandy alluvial sediments; 7silty sandy alluvial sediments; 8cemented gravelly-sandy alluvial sediments; 9palaeosols. legend fig. 2c: 1presentday soil and palaeosol interbedded between the alluvial sediments; 2silty alluvial sediments; 3sandy alluvial sediments; 4sandy-gravelly alluvial sediments. c. giraudi 201 inghiottitoi carsici, allo sbocco della valle che raccoglie la maggior parte del drenaggio di campo imperatore (2c in fig. 1), vi sono sedimenti alluvionali che formano un terrazzo sospeso di circa due metri sul fondovalle attuale. tale terrazzo, che corrisponde al più basso di fonte della macina, è costituito prevalentemente da sabbie e sabbie limose, che diventano sabbie ghiaiose verso il tetto (fig.2c). intercalato nella porzione mediobassa delle sabbie vi è un paleosuolo che è stato datato 1450±50 bp (beta-162900; 530÷670 cal ad). 22..44.. llee aalllluuvviioonnii eedd ii ccoonnooiiddii aalllluuvviioonnaallii ddii ffoonnttaarrii nella zona occidentale di campo imperatore, in zona fontari (3a in fig. 1) una serie di piccoli conoidi si sono sviluppati allo sbocco di alcune modeste incisioni che tagliano prevalentemente i depositi del versante meridionale del m. aquila. tra i depositi incisi vi sono cordoni di un antico rock glacier (giraudi & frezzotti, 1997), coperti da sedimenti lacustri ed alluvionali depostisi nella depressione compresa tra i cordoni frontali del rock glacier e la base del versante. i sedimenti lacustri coprono un paleosuolo (giraudi, 1998) datato 3440±60 bp (3770÷3430 cal bp). alle spalle del rock glacier c’è stata quindi sedimentazione alluvionale posteriore a tale data, mentre la fase di incisione di tali sedimenti, che ha dato luogo allo sviluppo dei piccoli conoidi alluvionali posti al piede del versante, appare ancora successiva. 22..55.. iill ccoonnooiiddee ddeell mm.. ffaaeettoo il conoide alimentato dalla valle compresa tra il versante settentrionale del m. faeto ed il m. brancastello (fig. 1) ha fornito varie indicazioni utili per ricostruire l’evoluzione della sedimentazione alluvionale a campo imperatore. tale conoide, sviluppatosi dopo il ritiro dei ghiacciai sia dal suo bacino di alimentazione che dall’apparato morenico di coppe di santo stefano (giraudi & frezzotti, 1997), ha invaso la vallecola che, tagliando gli apparati morenici dell’ultimo massimo glaciale e delle sue fasi di ritiro, permetteva il drenaggio verso est delle acque della estrema porzione occidentale di campo imperatore (3b in fig. 1; fig. 3b). nelle fasi iniziali, i sedimenti alluvionali hanno prodotto la copertura di un paleosuolo datato 12.100±100 bp (14.410÷13.770 cal bp) ed hanno sbarrato la vallecola; allorché il clima diventò più umido, lo sbarramento provocò la formazione di un lago stretto ed allungato ad ovest del conoide (giraudi, 1998;2001). i sedimenti lacustri basali sono stati datati 6090±70 bp (7190÷6770 cal bp), mentre quelli della parte intermedia sono stati datati 5640±60 bp (6630÷6290 cal bp). in seguito il lago si svuotò a causa dell’erosione della soglia e si produsse un’incisione nei sedimenti lacustri che venne riempita da altri sedimenti alluvionali. a valle della zona ove avvenne lo sbarramento della valle (fig. 3b), vi è un secondo corpo alluvionale che copre un paleosuolo sviluppatosi su una superficie di erosione: il paleosuolo è stato datato 4070±70 bp (beta-168676; 4830÷4410 cal bp). un terzo corpo alluvionale copre un paleosuolo che si sviluppa su una blanda superficie di erosione presente al tetto delle alluvioni precedenti; il paleosuolo è stato datato 2130±50 bp (beta-168677; 2190÷1990 cal bp). nella zona apicale dello stesso conoide (3c in fig. 1), il deposito alluvionale che forma il terrazzo più antico, corrispondente a quello che copre il paleosuolo datato 12.100±100 bp (14.410÷13.770 cal bp), è costituito da ghiaie sabbiose nella parte bassa e da massi e ghiaia in matrice sabbiosa nella parte alta; intercalato ai sedimenti alluvionali è presente un paleosuolo (giraudi & frezzotti, 1997), datato 7060±70 bp (8120÷7910 cal bp). un secondo deposito alluvionale appare incassato nel primo: è costituito da ghiaie e ghiaietto in abbondante matrice sabbiosa e copre un paleosuolo sviluppatosi sulla superficie di erosione che incide i sedimenti alluvionali più antichi. il paleosuolo è stato datato 5200±60 bp (bo-285; 6170÷5750 cal. bp). 22..66.. zzoonnaa aa nnoorrdd--oovveesstt ddeell mm.. ssaann ggrreeggoorriioo ddii ppaaggaanniiccaa in una porzione molto piatta di campo imperatore (3d in fig. 1), alle spalle dei depositi morenici, a nord ovest del monte san gregorio di paganica, è stata rinvenuta una alternanza di sedimenti alluvionali prevalentemente sabbiosi, con intercalazioni ghiaioso-sabbiose al tetto, e paleosuoli (fig. 3d): il primo paleosuolo è datato 1410±40 bp (cal. 580÷689 ad – beta-164916); il secondo, che appoggia su una superficie inclinata, è stato coperto in momenti diversi dai sedimenti alluvionali; le datazioni hanno indicato età di 1140±50 bp (cal. 780÷1000 adbeta-162902) per la parte topograficamente più bassa della sua area di affioramento, e di 720±50 bp (cal. 1230÷1390 ad beta-162901) per quella a quota più elevata; vi è inoltre un ulteriore paleosuolo intercalato alle alluvioni che ha fornito una età di 800±50 bp (cal. 1160÷1290 ad beta-162903); l’ultimo paleosuolo è stato datato 380±40 anni bp (cal. 1440÷1640 ad beta-164915) ed è coperto dalle alluvioni più grossolane presenti nella sezione. dopo la sedimentazione delle alluvioni che coprono il paleosuolo più recente, vi è stata una fase erosiva, la deposizione di un piccolo corpo alluvionale e quindi una nuova fase di incisione ancora in corso. nella stessa zona, ma su un conoide posto poco a nord-ovest, un paleosuolo coperto da depositi alluvionali è stato datato 250±40 anni bp (beta-168678; cal ad 1520÷1800) nel complesso, a campo imperatore sono state individuate varie unità alluvionali oloceniche che danno luogo ad una serie di 5 terrazzi sospesi sul fondovalle attuale (fig. 4) e che trovano riscontro in varie zone appenniniche. il primo terrazzo alluvionale è costituito da alluvioni prevalentemente ghiaioso sabbiose, successive ad un paleosuolo datato 12.100±100 bp (14.410÷13.770 cal bp), e contenenti intercalato un paleosuolo datato 7060±70 bp (8120÷7910 cal bp). al piano aremogna, presso roccaraso (abruzzo), a quote simili a quelle di campo imperatore, frezzotti & giraudi (1989) segnalano la presenza di un sedimento alluvionale databile tra circa 10.000 e 7000 anni fa. il secondo terrazzo alluvionale, incassato nel precedente, è costituito da alluvioni prevalentemente sabbiose o formate da sabbia con ghiaietto, che contengono intercalato un paleosuolo datato rispettivamente 5200±60 bp (6170÷5750 cal. bp) e 5420±80 bp (6400÷5950 cal bp). i depositi alluvionali olocenici di ... 202 c. giraudi al piano aremogna, presso roccaraso (abruzzo), frezzotti & giraudi (1989) segnalano la presenza di un paleosuolo datato 5060±150 bp (6020÷5650 cal bp), intercalato a sedimenti alluvionali. il terzo terrazzo alluvionale è costituito da alluvioni ghiaioso-sabbiose che coprono un paleosuolo datato 4070±70 bp (4830÷4410 cal bp) e che inglobano un paleosuolo datato 2130±50 bp (2190÷1990 cal bp). sulle sponde del lago ballano (appennino reggiano, quota 1550 m s.l.m.m.) ricerche in corso hanno evidenziato la presenza di sedimenti alluvionali che coprono torbe datate 4060±60 anni bp (4810÷4420 cal bp – beta-154565). il quarto terrazzo alluvionale appare costituito da un’alternanza di depositi prevalentemente fini e di suoli intercalati, datati 1410±40 bp (580÷689 ad), 1140±50 bp (780÷1000 ad); 720±50 bp (1230÷1390 ad), 800±50 bp (1160÷1290 ad) e 380±40 anni bp (1440÷1640 ad). nella valle parma di budignana, a quota 1530 m s.l.m.m. presso il lago scuro, ricerche in corso hanno evidenziato che un sedimento alluvionale 203 fig. 4 – schema dei rapporti stratigrafici tra i sedimenti alluvionali olocenici di campo imperatore. stratigraphic sketch through the holocene campo imperatore alluvial sediments. fig. 3 – sezioni geologiche schematiche dei sedimenti alluvionali studiati nella porzione occidentale di campo imperatore. legenda fig. 3a: 1sedimenti alluvionali; 2sedimenti lacustri; 3accumulo di rock glacier; 4substrato carbonatico meso-cenozoico; 5paleosuolo. legenda fig. 3b: 1sedimenti alluvionali sabbioso-limosi; 2sedimenti alluvionali sabbiso-ghiaiosi; 3sedimenti alluvionali ghiaiososabbiosi della terza fase del conoide; 4sedimenti alluvionali ghiaioso-sabbiosi della seconda fase del conoide; 5sedimenti sabbiosi e limosi lacustri; 6 sedimenti alluvionali ghiaioso-sabbiosi della prima fase del conoide; 7sedimenti ghiaioso-sabbiosi fluvioglaciali; 8depositi morenici; 9paleosuoli. legenda fig. 3c; 1sedimenti dell’alveo attuale; 2sedimenti alluvionali sabbioso-ghiaiosi; 3ghiaie sabbiose con blocchi; 4ghiaie sabbiose della prima fase del conoide; 5-substrato carbonatico meso-cenozoico; 6paleosuoli. legenda fig. 3d: 1suolo attuale e paleosuoli intercalati; 2sedimenti alluvionali prevalentemente sabbioso-limosi; 3sedimenti alluvionali sabbiosi; 4sedimenti alluvionali sabbioso-ghiaiosi. stratigraphic sketch through the alluvial sediments in western campo imperatore. legend fig. 3a: 1alluvial sediments; 2lacustrine sediments; 3debris forming the body of the rock glacier; 4bedrock; 5palaeosol. legend fig. 3b : 1silty-sandy alluvial sediments; 2sandy-gravelly alluvial sediments; 3gravelly-sandy alluvial fan sediments of phase iii ; 4gravelly-sandy alluvial fan sediments of phase ii ; 5sandy-silty lacustrine sediments; 6gravelly-sandy alluvial fan sediments of phase i; 7gravelly-sandy fluvioglacial sediments; 8till; 9palaeosols. legend fig. 3c: 1alluvial sediments in presentday stream bed; 2sandy-gravelly alluvial sediments; 3sandy gravels with boulders; 4gravelly sandy alluvial fan sediments of the phase i; 5bedrock; 6palaeosols, legend fig. 3d: 1presentday soil and palaeosols interbedded between the alluvial sediments; 2silty-sandy alluvial sediments; 3sandy alluvial sediments; 4sandy-gravelly alluvial sediments. ➧ contiene un tronco fluitato datato 1310±60 bp (640÷870 cal. ad – beta-154566) l’ultimo terrazzo appare in via di colonizzazione ad opera della vegetazione e, come dimostra lo sviluppo successivo ad eventi deposizionali, erosivi e pedogenetici più recenti dei secoli xv-xvii, il suo modellamento deve essere avvenuto in tempi molto recenti. 33.. ddiissccuussssiioonnee i depositi alluvionali di campo imperatore si sono sedimentati in vari periodi dell’olocene, ma la loro granulometria indica che l’energia dei corsi d’acqua che li ha depositi era molto diversa. nel corso della sedimentazione del corpo alluvionale che costituisce il primo terrazzo, avvenuta in un periodo compreso tra 12.100±100 bp (14.410÷13.770 cal bp) e 5420±80 bp (6400÷5950 cal bp) la forte energia dei corsi d’acqua evidenzia una situazione di resistasia, e quindi di instabilità dei versanti, anche se attorno a 7060±70 bp (8120÷7910 cal bp) i depositi alluvionali olocenici di ... deve esserci stato un episodio di durata non ben definibile di biostasia, durante il quale, grazie alla stabilità morfologica, si è sviluppato un suolo. nel corso della sedimentazione del corpo alluvionale che forma il secondo terrazzo, datato tra 7060±70 bp (8120÷7910 cal bp) e 4070±70 bp (4830÷4410 cal bp), la granulometria dei sedimenti, piuttosto fine, sembra testimoniare una fase di limitata resistasia; lo sviluppo di suoli datati attorno a 5200±60 bp (6170÷5750 cal. bp) e 5420±80 bp (6400÷5950 cal bp) testimoniano il verificarsi di un periodo di biostasia e di stabilità morfologica. tra la sedimentazione di questo corpo alluvionale ed il successivo, attorno a circa 4070±70 bp (4830÷4410 cal bp) deve essersi verificata una fase di biostasia che ha prodotto lo sviluppo del suolo di tale età. nel corso della sedimentazione del corpo alluvionale che forma il terzo terrazzo, costituito da sedimenti piuttosto grossolani, datato tra 4070±70 bp (4830÷4410 cal bp) e un periodo successivo a 2130±50 bp (2190÷1990 cal bp) e precedente a 1410±40 bp (580÷689 ad), deve essersi verificata una fase di resistasia e di instabilità dei versanti, interrotta da una breve fase di biostasia attorno a 2130±50 bp (2190÷1990 cal bp), allorché si sviluppò un suolo. la sedimentazione delle alluvioni che formano il quarto terrazzo deve essere avvenuta sotto condizioni ambientali variabili caratterizzate da moderata resistasia, data la granulometria prevalentemente fine dei sedimenti, e da vari periodi di biostasia nel corso dei quali si sviluppavano i suoli. solo dopo lo sviluppo del suolo datato 1440÷1640 ad aumentò l’energia dei corsi d’acqua e quindi si instaurò una fase di resistasia più marcata. poiché le fasi alluvionali registrate a campo imperatore sono state anche riconosciute in altre località dell’appennino settentrionale e centrale, a quote simili a quelle dell’area oggetto del presente studio, si assume che siano state innescate da variazioni ambientali risentite almeno nell’italia peninsulare. le fasi alluvionali descritte sono ben correlabili con le espansioni del ghiacciaio del calderone posto sul versante nord-orientale del corno grande (fig. 1), sul gran sasso, segnalate da giraudi (2000; 2002). il ghiacciaio si riformò e si espanse dopo lo sviluppo di un suolo datato 3895±65 anni bp (4520÷4110 cal. bp), un momento molto vicino all’inizio della sedimentazione delle alluvioni che formano il terzo terrazzo. una ulteriore espansione glaciale provocò la copertura di un suolo datato 1450±40 bp (cal. 540÷660 ad); è quindi contemporanea alla copertura di suoli ad opera delle alluvioni basali del complesso di sedimenti che forma il quarto terrazzo. una nuova espansione glaciale ebbe luogo tra 1450±40 bp (cal. 540÷660 ad) e 670±40 anni bp ( cal. 1270÷1400 ad), contemporaneamente alla sedimentazione della porzione intermedia dei sedimenti che formano il quarto terrazzo. il ghiacciaio del calderone raggiunse la sua massima espansione tardo-olocenica nel corso di un’avanzata successiva a 670±40 anni bp (cal. 1270÷1400 ad), quindi nel corso della cosiddetta piccola età glaciale, quando si formava la porzione sommitale, più grossolana, dei sedimenti alluvionali del quarto terrazzo di campo imperatore. oltre alle correlazioni con le fasi di avanzata del ghiacciaio del calderone, possiamo osservare altri elementi di correlazione tra la sedimentazione alluvionale a campo imperatore e le fasi di avanzata glaciale registrate in altre aree. la fase di sedimentazione alluvionale che forma il secondo terrazzo, successiva ai suoli datati attorno a 5000 anni bp (date non calibrate), coincide con l’inizio della cosiddetta neoglaciazione (orombelli & ravazzi, 1996). la copertura del paleosuolo, datato 780÷1000 ad, ad opera del complesso di sedimenti alluvionali che costituiscono il quarto terrazzo, coincide con una fase di avanzata glaciale registrata sulle alpi. infatti le morene del ghiacciaio della brenva (m. bianco) in fase di avanzata hanno coperto un albero datato 1170±75 14c years bp (760÷980 cal. ad: orombelli & porter, 1982), mentre le morene di una fase di avanzata del ghiacciaio del lys, sul massiccio del m. rosa, coprono un paleosuolo datato 1185±80 14c years bp (734÷980 cal. ad; strumia, 1997). 44.. ccoonncclluussiioonnii il rilevamento geologico e geomorfologico di dettaglio eseguito sui sedimenti e sui terrazzi alluvionali di campo imperatore ha permesso di distinguere varie fasi di sedimentazione oloceniche. la scansione cronologica dell’attività alluvionale, ottenuta per mezzo di datazioni radiocarbonio su paleosuoli e sedimenti lacustri, dimostra come il trasporto solido nei corsi d’acqua sia avvenuto, seppure con diversa energia e con brevi fasi di interruzione, lungo gran parte dell’olocene. appare poi evidente la correlazione tra fasi di sedimentazione alluvionale a campo imperatore e quelle riconosciute in altre località dell’appennino centrale e settentrionale, ma anche con le fasi di espansione del ghiacciaio del calderone e di alcuni ghiacciai alpini. le fasi alluvionali di campo imperatore sono quindi strettamente legate all’impatto sull’ambiente prodotto da variazioni climatiche risentite sia in area mediterranea che alpina, evidenziate anche da proxy-data, quali i ghiacciai, che non possono essere influenzati dall’intervento dell’uomo. anche se si hanno indizi di incendi preistorici di origine antropica (giraudi,1999), i dati sembrano dimostrare che l’impatto umano non è stato in grado di produrre una destabilizzazione dei versanti e di dare luogo a fasi di sedimentazione alluvionale indipendenti da quelle prodotte dalle variazioni climatiche. la presenza di molti ed estesi corpi sedimentari di origine alluvionale appare strettamente legata alla esistenza di vaste fasce di cataclasiti presso la base del versante che borda la porzione settentrionale di campo imperatore; i molti gullies incisi in questa zona si sono stabilizzati solo rare volte, forse in coincidenza con le maggiori fasi di stabilità morfologica, mentre per gran parte dell’olocene l’erosione è stata attiva ed ha fornito materiale clastico per il trasporto solido nell’alveo dei corsi d’acqua. il notevole dettaglio di fasi di sedimentazione e di pedogenesi registrate nei sedimenti che formano il quar204 c. giraudi to terrazzo (di età storica) appare sostanzialmente legato al fatto che il sito studiato si trova in un’area molto piatta: in tali zone i corsi d’acqua perdono energia, la sedimentazione è prevalentemente fine e le superfici di erosione sono assai blande. in alcune aree pianeggianti della porzione occidentale di campo imperatore si verificano quindi le condizioni adatte alla preservazione dei sedimenti deposti dalle fasi alluvionali secondarie che, nel loro complesso, hanno formato il quarto terrazzo. un dettaglio simile non è stato però trovato nei depositi alluvionali più antichi, rilevati in zone ove i corsi d’acqua avevano maggiore energia e dove la sedimentazione era più grossolana e le fasi di erosione assai più intense. rriinnggrraazziiaammeennttii il presente lavoro è stato condotto coi contributi finanziari del ministero per l’ambiente nell’ambito dell’accordo di programma enea – ministero dell’ambiente, progetto 2,4 – variazioni climatiche, e del parco nazionale gran sasso-monti della laga. rriiffeerriimmeennttii bbiibblliiooggrraaffiiccii demangeot j. (1965) – géomorphologie des abruzzes adriatiques. mem. et doc. , c.n.r.s., 403 pp. frezzotti m. & giraudi c. (1989) evoluzione geologica tardo-pleistocenica ed olocenica del piano di aremogna (roccaraso abruzzo): implicazioni climatiche e tettoniche. mem. soc. geol. it., 4422, 519. frezzotti m. & giraudi c. (1990) – sedimenti eolici tardopleistocenici ed olocenici nell’appennino centrale. mem.soc.geol.it., 4455, 883-886. ghisetti f. & vezzani l. (1986) – carta geologica del gran sasso d’italia (da vado di corno a passo delle capannelle). s.e.l.c.a., firenze. ghisetti f. & vezzani l. (1990) – carta geologica del gruppo del m. siella-m. camicia-m. prenam. brancastello (gran sasso d’italia, abruzzo). caratteri stratigrafici e strutturali del settore orientale della catena del gran sasso. s.e.l.c.a., firenze. giraudi c. (1994) elementi di geologia del quaternario della piana di campo imperatore (massiccio del gran sasso italia centrale). in atti tic. sc. terra (serie speciale), 22, 137-143. giraudi c. (1998) i laghi effimeri tardopleistocenici ed olocenici di campo imperatore e del massiccio del gran sasso d'italia (abruzzo italia centrale). il quaternario, 1111 (2), 217-225. giraudi c. (1999) incendi di età pleistocenica superiore e olocenica sulle montagne dell'appennino centrale. il quaternario, 122(2), 143-146. giraudi c. (2000) le oscillazioni oloceniche del ghiacciaio del calderone, gran sasso d'italia (abruzzo italia). il quaternario, 1133(1/2), 31-38. giraudi c. (2001) the late pleistocene and holocene temporary lakes in the abruzzo parks and the central apennine. in visconti g., beniston m., iannorelli e. & barba d. eds: global change and protected areas. advances in global changes research, 99, 445-458. giraudi c. (2002) – le oscillazioni del ghiacciaio del calderone (gran sasso d’italia, abruzzo – italia centrale) e le variazioni climatiche degli ultimi 3000 anni. il quaternario, 1155(2), 145-150. giraudi c. & frezzotti m. (1997) late pleistocene glacial events in the central apennine, italy. quaternary research, 4488 (3),280-290. orombelli g. & porter s.c. (1982) late holocene fluctuations of brenva glacier. geogr. fis. dinam. quat. 55,13-37. orombelli g. & ravazzi c. (1996) – the late glacial and early holocene chronology and paleoclimate. il quaternario, 9(2), 439-444. servizio geologico d’italia (1963) carta geologica d’italia a scala 1:100.000, f. 140, teramo. ii edizione. strumia g. (1997) oscillazioni glaciali precedenti la piccola età glaciale documentate da un suolo sepolto in una morena del ghiacciaio del lys. il quaternario, 1100(2), 153-158. 205 ms. ricevuto il 13 maggio 2003 testo definitivo ricevuto il 10 giugno 2003 ms. received: maj 13, 2003 final text received: june 10, 2003 i depositi alluvionali olocenici di ... imp. nisio ii ffeennoommeennii ddii sspprrooffoonnddaammeennttoo:: ssttaattoo ddeellllee ccoonnoosscceennzzee eedd aallccuunnii eesseemmppii iinn iittaalliiaa cceennttrraallee sstteeffaanniiaa nniissiioo dipartimento dei servizi tecnici nazionali servizio geologico nazionale v. curtatone, 3 00185 roma riassunto nella letteratura nazionale ed internazionale sono stati da tempo codificati numerosi termini per indicare i vari tipi di cavità che si aprono nel terreno, attualmente però viene sempre più spesso utilizzato il termine sinkhole per definire queste forme, spesso omologhe, ma sviluppatesi attraverso processi genetici differenti. così tale termine risulta piuttosto semplificativo e generico. questo lavoro si propone perciò di riesaminare la terminologia con la quale sono state indicate le varie forme in relazione alla loro genesi e di proporre una definizione più precisa del termine sinkhole. nella letteratura italiana per indicare i vari tipi di cavità subcircolari furono introdotti sin dai tempi più antichi i termini di dolina (geneticamente distinta in diversi tipi), sprofondamento e camino di collasso. nel primo caso il processo morfogenetico si sviluppa in rocce solubili per dissoluzione attraverso l’infiltrazione d’acqua di ruscellamento. nel secondo caso i fattori predisponenti sono la gravità e l’antropizzazione, nel terzo invece i fattori principali dell’evoluzione di tali forme, oltre alla dissoluzione sono costituiti dalla risalita di fluidi aggressivi e dai fenomeni di aumento e di diminuzione di pressione indotti dalle oscillazioni della tavola d’acqua al di sotto del piano campagna. anche nella letteratura anglosassone per le cavità carsiche era utilizzato il termine doline (suddiviso poi in vari tipi) equivalente alla dolina della letteratura italiana; in seguito esso è stato quasi del tutto sostituito dal termine sinkhole. quest’ultimo è stato utilizzato la prima volta per indicare depressioni subcircolari dovute al crollo di piccole cavità carsiche, sinonimo quindi di dolina, successivamente è stato adottato per indicare gli sprofondamenti di qualsiasi genere. prendendo in considerazione i meccanismi genetici che favoriscono lo sviluppo degli sprofondamenti s.l. il termine sinkhole in senso stretto dovrebbe essere adottato soltanto per quelle forme in cui il processo genetico principale è la risalita dei fluidi dal basso, attraverso reticoli di fratture che mettono in comunicazione un substrato carsificato con i sedimenti superficiali, con conseguenti fenomeni di piping o suffosione. esso sarebbe pertanto sinonimo dei termini camino di collasso o voragine di terra della letteratura italiana e di piping sinkhole della letteratura anglosassone. i casi di sinkhole in italia risultano concentrati nelle piane alluvionali, nelle immediate vicinanze di dorsali carbonatiche, in contesti geologico-strutturali ed idrogeologici complessi innescati da cause di diversa natura (sismi, siccità, alluvioni, emungimenti di acque etc.). la presenza di un pacco di sedimenti impermeabili o semi-permeabili, al tetto di un substrato carbonatico carsificato, un reticolo di faglie e diaclasi che mettano in comunicazione i due mezzi, sono fattori predisponenti essenziali. inoltre la presenza di fluidi liquidi e gassosi nel sottosuolo, co2 e h2s, che consentano la dissoluzione e di conseguenza il sifonamento dei materiali di copertura è stata riscontrata nella maggioranza dei casi. abstract technical literature offers a lot of terms to indicate different types of geological cavities, but recently the term sinkhole seems to be commonly adopted to indicate underground cavities which are similar in their features but have different morphogenetic origins. that is why the term sinkhole appears to be rather generic or inadequate. the aim of this work, therefore, is to propose a new terminology for every kind of cavity and to associate a more rigorous definition to each of them, according to their different morphological genesis. in the italian traditional literature the terms “dolina” (divided in various types), “sprofondamento” and “camino di collasso” were adopted to indicate different kinds of sub-circular collapses. according to the first term the soil dissolution is caused by the infiltration of water in soluble rocks; according to the second one gravity and anthropizzation are the main factors causing these collapses and according to the last one, above the soil dissolution, the predisposing factor is the pressure of the water coming back to the plane surface level. in the english literature the term doline (still divided in several types) was originally adopted to indicate karst caves as an equivalent of the italian word “dolina” but it was later replaced by the term sinkhole. at first this term simply indicated sub-circular depressions due to the landslide of small karst caves, but actually it is adopted to indicate every kind of cavity. taking into account the processes that cause the development of a sinkhole, the use of this term seems only suitable to indicate cavities caused by a piping process (“suffosione” in italian) and therefore it should be a synonymous of the italian term “camino di collasso” (known as piping sinkhole in the english literature). the sinkholes in italy are concentrated in alluvial flats, near carbonatic ridges, in some structural and hydrogeological contexts which were originated by different causes (earthquakes, dryness, alluviums, water wells etc.). impermeable sediments laid on the top of karst carbonatic bedrocks, faults and fractures between the two layers, are the main predisposing factors. moreover, the presence of water and gases, such as co2 and h2s, concurring to the dissolution and the piping processes, has been detected in almost all the circumstances. parole chiave: sinkhole, sprofondamenti, suffosione. keywords: sinkhole, sinking, piping il quaternario italian journal of quaternary sciences 1166(1), 2003, 121-132 122 s. nisio iinnttrroodduuzziioonnee i fenomeni di sprofondamento sono riconosciuti in diverse parti del mondo. negli stati uniti (california, florida) tali fenomeni sono particolarmente diffusi e costituiscono una delle maggiori calamità naturali scarsamente prevedibili e dalle quali non è facile difendersi (sinclair & steward, 1985; newton, 1987; wilson & shock, 1996). in florida il fenomeno è talmente frequente che il servizio geologico nazionale ha predisposto siti internet, destinati alla popolazione, per denunciare in tempi reali il verificarsi di sprofondamenti tipo sinkhole. le cause naturali sono generalmente preponderanti mentre le cause antropiche sono concause o accessorie anche se nell’ultimo ventennio si è registrato un aumento dei casi in tutto il mondo in seguito probabilmente proprio all’espansione urbanistica (sinclair, 1982; newton, 1987; tihansky & galloway, 2000). ii ffeennoommeennii ddii sspprrooffoonnddaammeennttoo recentemente per indicare gli sprofondamenti di qualsiasi genere viene utilizzato, da esperti del settore e non, il termine sinkhole, che ha quasi del tutto sostituito altri termini più specifici, generando una notevole confusione terminologica. un uso più corretto del termine sinkhole permetterà di individuare meglio il tipo di sprofondamento cui ci si vuole riferire. il termine sinkhole (che tradotto letteralmente significa “pozzo di scarico”, “buco di scolo”) è stato introdotto per la prima volta da fairbridge (1968) e successivamente da monroe (1970) per indicare una depressione di forma sub-circolare dovuta al crollo di piccole cavità carsiche sotterranee. infatti alcuni autori, monroe (1970), jennings (1985), white (1988), ed altri distinguono fenomeni di solution sinkhole, collapse sinkhole e subsidence sinkhole (coincidenti con i termini di solution doline, collapse doline, subsidence doline introdotti da cramer, 1941 e successivamente utilizzati da castiglioni nel 1986 in italia e da molti altri autori), pertanto il termine sinkhole sarebbe sinonimo di dolina. attualmente negli stati uniti e in gran bretagna il temine sinkhole viene usato frequentemente e definisce una qualunque cavità nel terreno di forma sub-circolare originatasi per motivi diversi. beck, (1984), beck & wilson, (1987), berti et al., (2002 a) utilizzano tale termine per indicare anche cavità, di forma non necessariamente sub-circolare, apertesi nel terreno per cause antropiche. anche in italia di recente (a partire dagli anni novanta) è stato adottato il termine sinkhole (faccenna et al., 1993, brunamonte et al., 1994; nolasco, 1998; ciotoli et al., 1998 e molti altri) per indicare una cavità sub-circolare, che si apre improvvisamente nel terreno, con richiamo di materiali verso il basso. esso pertanto sarebbe sinonimo di sprofondamento s.l. ed è applicabile a fenomeni come le doline di crollo, gli sprofondamenti di natura antropica, i camini di collasso o voragini di terra, che si aprono nei terreni a granulometria variabile. la dolina di crollo ( cramer, 1941, castiglioni, 1986) indica una depressione tipica di aree carsiche, che si forma principalmente per dissoluzione dovuta all’assorbimento nel terreno di acqua da ruscellamento (anelli, 1959; 1965, sweeting, 1972; ford & williams, 1989; klimchouck et al., 1997; ferrarese & sauro 2001; macalluso et al., 2002), cui si aggiunge il crollo per gravità della parte superiore della cavità. uno sprofondamento in genere è una depressione di forma varia, anche se generalmente sub-circolare, formatasi rapidamente, tipica oltre che di zone carsiche, di aree di pianura, di aree in cui nel sottosuolo sono presenti altre cavità (canuti, 1982). lo sprofondamento catastrofico, poiché improvviso ed arrecante danni, comprende anche quei dissesti non direttamente collegabili a fenomeni carsici, come le cavità sotterranee originate dall’attività antropica, in aree urbanizzate, da miniere, scavi, cunicoli e cavità di antiche catacombe.gli sprofondamenti sono legati principalmente alla gravità. i “camini di collasso” o “voragini di terra” sono ampie e profonde depressioni sub-circolari con dimensioni da pochi metri al centinaio di metri e profondità di alcune decine di metri, a pareti sub-verticali che si aprono rapidamente in terreni a granulometria variabile. i camini di collasso sono in genere colmati da acque, spesso mineralizzate, formando laghetti e specchi d’acqua; sono caratterizzati da subsidenza che può localmente essere dovuta a presenza di sorgenti. sono localizzati in genere su allineamenti tettonici lungo i quali spesso si evidenziano anomalie di fluidi liquidi e gassosi; la continua erosione delle pareti del camino provoca il progressivo colmamento della voragine, un aumento del diametro e nello stesso tempo una diminuzione della profondità dello specchio d’acqua. la formazione dei camini di collasso è improvvisa ma può essere realizzata in un evento unico o in più eventi con progressivo cedimento delle pareti (brunamonte et al., 1994). nel primo caso il substrato è interessato da un condotto unico e la cavità presenta nel tempo dimensioni più o meno stazionarie. nel secondo caso lo sviluppo del camini di collasso avviene per lento dilavamento dal basso verso il tetto della cavità; la cavità stessa tende ad allargarsi notevolmente per cedimento progressivo e coinvolgimento di volumi sempre più grandi. si è constatato che la maggior parte di tali fenomeni è dovuta ad una serie di cause, di cui si parlerà in seguito, ma ruolo importante assumono i processi di risalita, sifonamento e suffosione, (sensu castiglioni, 1986) (derbyshire & mellors, 1988; derbyshire et al., 1991; billiard et al., 1992; 1993; muxart et al., 1994). un processo di suffosione, definito da castiglioni (1986), è un effetto meccanico dello scorrimento subsuperficiale dell’acqua nel terreno (con dimensioni granulometriche dalle argille alle ghiaie) che si realizza quando quest’ultimo è crepacciato o poroso e quando l’acqua abbondante e con pressione elevata, riesce a trovare vie di scorrimento in cui passare con velocità abbastanza sostenuta. il passaggio dell’acqua provoca l’erosione di materiale e la formazione di canalicoli a sviluppo sub-orizzontale e di condotti tubolari lungo le linee idrauliche di flusso. quest’ultimo fenomeno viene indicato nella letteratura anglosassone con il termine piping. pertanto nel processo di formazione dei camini di collasso dovrebbe avere un ruolo importante la pressione idraulica iniziale nei condotti (guerricchio, 1982). sprofondamenti in cui è stata accertata la presenza di meccanismi di questo tipo tipo sono noti in letteratura anglosassone come piping sinkhole. secondo forti (2002) i fenomeni di piping si possono verificare in un sistema carsico, solo se l’acquifero termale non è confinato ed è situato a breve distanza dalla superficie. infatti secondo l’autore i meccanismi di piping non si possono sviluppare in un sistema carsico termale posto a notevole profondità e ricoperto da rocce impermeabili proprio perché la presenza di queste ultime impedirebbe ai processi di progredire, dal basso verso l’alto, in superficie. i fenomeni registrati nell’appennino ed in altre parti del mondo mostrano che i fenomeni di sinkholes, dovuti a fenomeni di risalita di fluidi dal basso, si sono formati nella maggior parte dei casi proprio in acquiferi imprigionati, con substrato posto a notevole profondità, sormontato da depositi costituiti da materiali a granulometria variabile, ma generalmente da limi, a scarso stato di consistenza, in presenza di faglie o fratture (littlefield et al., 1984; derbyshire & mellors, 1988; derbyshire et al., 1991; billiard et al., 1992; 1993; faccenna, 1993; muxart et al., 1994; ciotoli et al., 2000; berti et al., 2002 a, b; di filippo et al., 2002). pertanto sembrerebbe che proprio la presenza di faglie e diaclasi, che mettano in comunicazione i due mezzi, (permeabile di base ed impermeabile al tetto) sia la spiegazione dell’innesco di sinkhole in acquiferi imprigionati. i meccanismi di piping e suffosione sub-superficiale potrebbero essere catturati dal basso sulla direttrice a sviluppo verticale verso l’alto delle cavità carsiche, proprio per la presenza di faglie e diaclasi all’interno dei terreni di copertura posti al di sopra del bedrock carbonatico. in conclusione viene riportata la terminologia con la quale vengono indicati i diversi tipi di cavità che si aprono nel terreno. sprofondamento: è una cavità di forma varia, anche se generalmente sub-circolare, formatasi rapidamente, tipica di zone carsiche, di aree di pianura, di aree urbane, di aree il cui sottosuolo presenti altre cavità anche di origine antropica; sprofondamento catastrofico: sprofondamento rapido ed improvviso arrecante danni a persone o cose; sprofondamento di origine antropica (che potremmo definire anthropogenic sinkhole): è il collasso di una volta in cavità di origine antropica; “dolina di soluzione normale” (coincidente con il termine anglosassone di “solution sinkhole” e “solution doline”): conca chiusa originata per dissoluzione della roccia da parte dell’acqua di ruscellamento superficiale (castiglioni, 1986); “dolina alluvionale” (coincidente con il termine anglosassone di “subsidence sinkhole” o potrebbe meglio definirsi “cover sinkhole”): conca chiusa che si forma su materiali di copertura in genere, e/o alluvionali, in seguito all’originarsi, in rocce solubili sottostanti, di cavità carsiche per dissoluzione sub-superficiale o di crollo (castiglioni, 1986); “dolina di crollo” (coincidente con il termine anglosassone di “collapse sinkhole” e “collapse doline”): cavità con forma a pozzo nei calcari e in rocce solubili formatesi per il crollo del soffitto di grotte (cramer, 1941; castiglioni, 1986); “dolina di subsidenza in roccia” (coincidente con il 123i fenomeni di sprofondamento ... termine anglosassone di “rock subsidence sinkhole” o “subsidence doline”): cavità formatesi su rocce coerenti e permeabili ma non solubili, poggiate su rocce solubili per crollo di volta (castiglioni, 1986); sinkhole in senso stretto, o camino di collasso (coincidente con il termine anglosassone di piping sinkhole): cavità sub-circolare che si apre improvvisamente in terreni di varia granulometria, per meccanismi prevalenti di risalita delle acque e dei gas, di sifonamento di suffosione e di successivo collasso. in definitiva per una più corretta terminologia il termine sinkhole s.s. dovrebbe essere applicato esclusivamente a quelle cavità che si formano a seguito di processi non solamente carsici ma anche di risalita delle acque ed erosione e sifonamento dei materiali di copertura; termine equivalente così ai camini di collasso e alle voragini di terra della letteratura italiana e ai piping sinkholes della letteratura anglosassone. in alternativa sarebbe necessario aggiungere un attributo accanto al termine sinkhole per indicarne la genesi e per evitare di creare confusione circa il fenomeno cui si vuole riferire (piping, collapse, solution, subsidence, anthopic o anthropogenic, cover). per quanto riguarda gli sprofondamenti dovuti al carsismo è preferibile utilizzare il termine già esistente dolina di crollo (equivalente a collapse doline o collapse sinkhole della letteratura anglosassone), mentre per i collassi dovuti all’antropizzazione (crolli di grotte, cunicoli, miniere etc.) dove solo casualmente si formano cavità subcircolari, si può adottare il termine generico di sprofondamento antropico (o anthropogenic collapse). llee ccaauussee i sinkholes s.s. (o piping sinkhole) si formano per cause predisponenti ed innescanti. si originano in contesti di complesse situazioni geologico-strutturali ed idrogeologiche del territorio che ne costituiscono il substrato essenziale. vengono innescati per motivi di diversa natura quali un sisma, un periodo di siccità, o una alluvione (ciò che può provocare una variazione rapida del livello piezometrico), l’emungimento di grandi quantitativi di acqua dal sottosuolo. definire quale sia la causa principale è difficile poiché esse sono molteplici e generalmente concomitanti; queste possono così essere riassunte: 1) un substrato carbonatico o costituito da roccia solubile (calcari, dolomie, evaporiti o rocce solfatiche) sottoposto a fenomeni carsici; la presenza di una morfologia del bedrock accidentata, sia a piccola scala che a grande scala, con macroforme carsiche (doline, uvala, crepacci e grotte) e con cavità carsiche presenti al tetto del substrato (interfaccia suolo/roccia) risultato di processi corrosivi e pedogenetici; 2) la presenza di un pacco di sedimenti impermeabili o semi-permeabili al tetto del substrato, costituito da limi, argille, sabbie a differente granulometria, omogenee o eterogenee; 3) scarse caratteristiche fisico-meccaniche dei materiali costituenti il manto superiore (consolidazione, addensamento, resistenza); 4) presenza di un reticolo di fratture o faglie che permettano una maggiore circolazione idrica e una 124 notevole erosione meccanica; 5) presenza di abbondanti acque di circolazione sotterranea; 6) presenza di gas nel sottosuolo, generalmente co2 e h2s, che consentano la dissoluzione dei materiali di copertura e la risalita delle acque (faccenna et al., 1993; ciotoli et al., 1998); 7) intensità elevata delle precipitazioni piovose e alternanza di periodi secchi e piovosi, risultano particolarmente favorevoli alla formazione delle oscillazioni della tavola d’acqua; 8) le attività antropiche: attività estrattive, emungimenti di acqua; il forte emungimento per uso irriguo ed idropotabile fa sì che si sviluppino, in prossimità dei pozzi, coni di depressione tali da far aumentare notevolmente la velocità dei flussi idrici e quindi l’asportazione delle particelle dei sedimenti e subsidenza delle coperture alluvionali; 9) le eventuali escursioni termiche; in zone poste a quote elevate e soprattutto alle alte latitudini (nord europa), i passaggi al di sopra e al di sotto dello zero possono originare cunei e lenti di ghiaccio che tendono ad allargare le cavità nel terreno; 10) la scarsa presenza di un manto vegetale che possa esercitare un effetto limitante nei confronti della mobilizzazione dei terreni; 11) le scosse sismiche. ddoovvee ssii vveerriiffiiccaannoo i sinkholes si originano su piane alluvionali, pianure costiere, conche intermontane, generalmente di origine tettonica in corrispondenza di successioni carbonatiche massicce carsificate, sedi di falde acquifere di grande potenza, a cui si sovrappongono depositi fluvio-lacustri, lagunari, vulcanici o marini di potenza variabile (newton, 1984). se ne presentano di seguito alcuni esempi nell’appennino centrale (fig 1). fig 1 le aree interessate da fenomeni di sinkhole the areas interested from phenomena of sinkhole s. nisio 125 eesseemmppii nneell llaazziioo 11)) llaa ppiiaannaa ddii ss.. vviittttoorriinnoo, (ri) caratteri generali la piana di s. vittorino, attraversata dal f. velino, costituisce una depressione tettonica bordata da faglie che ne hanno favorito una particolare conformazione triangolare, con apice rivolto a sud (fig. 2). essa è caratterizzata da un notevole sviluppo di forme di collasso, presenti anche sui versanti circostanti; secondo la letteratura anglosassone sarebbe definita una sinkholes plain. poiché i fenomeni di sprofondamento hanno provocato e provocano tutt’ora notevoli danni alle strutture antropiche dell’area, questa è stata oggetto di studi specifici sin dai tempi più antichi (tenore 1872; verri 1886) che sono stati ulteriormente approfonditi di recente (nolasco, 1986; 1998; faccenna et al., 1993; ciotoli et al., 1998, 2000, bigi et al., 1999; centamore & nisio, 2002 a, b, 2003; bersani & castellano 2002). la piana è stata colmata da depositi fluvio-lacustri del pleistocene superiore-olocene, a differente granunometria, per la maggior parte costituiti da limi (60%), argille (20%), sabbie (10%), localmente si rivengono lenti di ghiaie, e travertini (per lo più sabbiosi), con spessori che variano aumentando verso il centro della piana fino ad un massimo di circa 130 -170 m; lungo i versanti della piana sono presenti lembi di travertini, di depositi terrazzati e di conoide, del pleistocene medio. i depositi continentali che colmano la depressione tettonica di s. vittorino ricoprono blocchi delle successioni affioranti a m.te paterno fagliati e dislocati verso il basso (centamore et al., 2003). questi blocchi sono costituiti prevalentemente da formazioni carbonatiche, sulle quali prima della fase tettonica distensiva che ha favorito la formazione della depressione, si sarebbero sviluppate forme carsiche, presenti tra l’altro sul versante di m.te paterno. sulla destra idrografica del fiume si elevano i m.ti reatini, mentre sulla sinistra sono presenti il rilievo carbonatico di m.te nuria e la dorsale di calcariola (fig. 2). la dorsale dei monti reatini, a n, è caratterizzata dalla sovrapposizione di una successione carbonatica pelagica (dell’unità dei m.ti reatini) su una successione carbonatica di piattaforma e silico-clastica dell’unità m.te nuria (centamore & nisio, a, b , 2003). il gruppo montuoso del m.te nuria, a se, è costituito da una potente successione carbonatica di piattaforma (piattaforma laziale-abruzzese) con quote che arrivano fino a 1850 m. la dorsale di calcariola è costituita prevalentemente dai depositi fluvio-lacustri del bacino di rieti che ricoprono un substrato costituito da arenarie (appartenenti all’unità del salto; centamore & nisio, 1999; 2002 a, b; 2003 centamore et al., 1999) e da termini carbonatici (dell’unità m.te navegna e dell’unità m.ti reatini). la piana è bordata da elementi tettonici distensivi e/o transtensivi che ne hanno condizionato la morfologia (da cui la caratteristica forma triangolare, centamore & nisio, 1999; 2002 a, 2003; centamore et al., in stampa; dramis & nisio, in stampa). il più importante di questi elementi è la faglia fiamignano-micciani, una dislocazione di importanza regionale a direzione nw-se ed immergente verso sw che si segue per chilometri (fig. 2), al di fuori della piana, pur essendo interrotta e spostata da faglie trasversali e oblique. la faglia mette a contatto le formazioni carbonatiche di m.te nuria con quelle prevalentemente torbiditiche della depressione del salto; attraversa tutta la valle del f. velino e continua più a nord, bordando il versante occidentale del gruppo montuoso del terminillo. il segmento che attraversa la piana di s. vittorino non è facilmente individuabile sul terreno, anche a causa dei continui e radicali interventi antropici, che dalla fine dell’ottocento hanno modificato drasticamente l’antico paesaggio lacustre; esso sembra coincidere con un allineamento micciani s. vittorino (faccenna et al., 1993; ciotoli et al., 1998; 2000; centamore & nisio, 2000). dal punto di vista idrogeologico la piana di san vittorino costituisce il luogo di recapito della circolazione idrica dei versanti limitrofi (boni et al., 1995, e da dall’aglio & campanile,1996, ciotoli et al., 1998; 2000, colombi et al., 1999; capelli et al., 2000) e, soprattutto, del sistema idrogeologico dei monti giano, nuria e velino. in questa zona le sorgenti presenti sono distribuite ai margini settentrionale e meridionale della pianura, hanno un carattere prevalentemente puntuale (con un’unica emergenza) e sono tra loro associate a costituire fronti di deflusso emergenti per trabocco della falda idrica indotto dalla coltre satura dei sedimenti alluvionali. le portate emergenti sui lati opposti della piana sono molto differenti tra loro: circa 2000 l/s per il bordo settentrionale rispetto ai circa 18000 l/s complessivi di quello meridionale (sorgenti del peschiera). alcune sorgenti puntuali sono poi presenti anche all’interno della piana con portate modeste (stimate tra 0.1 ÷ 2 l/s), poste in corrispondenza dei sinkholes. i sinkholes della piana la piana di s. vittorino, oggetto sin dalla fine del secolo scorso di una serie di interventi antropici che ne hanno modificato notevolmente il paesaggio, è caratterizzata dalla presenza di almeno 29 cavità sub-circolari (camini di collasso o sinkholes) che ospitano laghetti e piccole pozze, di sorgenti mineralizzate, in concentrazioni anomale dei fluidi gassosi, di altri numerosi piccoli sprofondamenti localizzati, ed emergenze di acqua dolce (fig 2). il primo sprofondamento di cui si ha menzione è quello che riguarda la chiesa di s. vittorino (edificata nel 1614), avvenuto nel 1703, in seguito ad una scossa sismica, che ha dato origine ad una cavità di circa 20 m di diametro e 2 m di profondità. si contano altri 5 sprofondamenti avvenuti nei secoli scorsi (tra il 1700 e il 1850; gli atlanti del 1808 ne mostrano solo due; bersani & castellano, 2002) di cui non si hanno informazioni certe. alcuni di essi sono stati riattivati nei primi decenni di questo secolo (nel 1915 e 1951; riccardi, 1951; mori, 1983;) le cavità hanno dimensioni variabili con diametri di 204, 130, 80, 50 e 15 m (tra cui il lago di paterno, il pozzo di mezzo, il pozzo burino) e profondità che variano da un massimo di 45 m a pochi metri (capelli & petitta, 1998; capelli et al., 2000). nel 1893 si aprirono improvvisamente altre 5 cavità con diametri da 100 a 8 m e profondità da 10 a 15 m e tra il 1900 e il 1903 ancora 5 con dimensioni di pochi metri. i fenomeni di sprofondamento ... 126 altre attivazioni, neoformazioni o allargamenti, si sono avute in occasioni di sismi (michetti et al., 1994), come avvenne durante il sisma del 1915, (pozzo gustavo, in seguito al terremoto di avezzano). nel 1986 in seguito ad alluvioni si aprono 3 voragini in località sciamargutta (nolasco, 1986; catenacci, 1992) con diametri da 5 a 60 m e profondità di una decina di metri. l’ultimo sinkhole, che si è formato nel 1993 presenta solo pochi metri di diametro. i sinkholes sono concentrati nella zona settentrionale della piana, tra s. vittorino e vasche, e sono allineati secondo direzioni ne-sw tra vasche e case paterno, e-w tra le terme di cotilila e s. vittorino e nw-se, nella fascia tra le sorgenti del peschieramicciani e terme di cotilia s. vittorino, in parte coincidente con il prolungamento settentrionale della faglia fiamignano-micciani, ad ovest della quale non si evidenziano più i fenomeni di sprofondamento (faccenna et al., 1993; nolasco, 1998; centamore et al., 1999; ciotoli et al., 2000, centamore & nisio, 2002, a, b, 2003; nisio, in stampa). le acque mineralizzate sono rappresentate principalmente da acque solfuree e da acque ferruginose; le emergenze sono concentrate prevalentemente ai piedi del versante di m.te paterno, tra s. vittorino e vasche, ma si rinvengono localizzate anche in sinistra del f. velino lungo l’allineamento nw-se piedimozza-cerquara. in particolare le acque ferruginose emergono in alcuni laghetti a se di s. vittorino, lungo l’allineamento corrispondente al prolungamento settentrionale della faglia fiamignano-micciani, mentre le sorgenti solfuree sono allineate con direzioni circa e-w, tra s. vittorino e vasche, e nw-se, tra pendenza e s. vittorino e tra piedimozza e cerquara, (faccenna et al., 1993; nolasco, 1998; ciotoli et al., 2000). per quanto riguarda i fluidi gassosi le anomalie di elio sono concentrate lungo un allineamento e-w tra s. vittorino e le terme di cotilia, e lungo due allineamenti nw-se, tra le sorgenti del peschiera e s. vittorino. quelle del radon si concentrano invece per la maggior parte nel settore nord-occidentale della piana e in misura minore lungo gli allineamenti micciani-s. vittorino a direzione nw-se, e con direzioni ne-sw tra vaschecase di paterno, e parallelamente al versante nordoccidentale del rilievo carbonatico di pendenza-colle impicciavera, (ciotoli et al., 2000). il lato settentrionale e quello sud-orientale della piana sono caratterizzati inoltre dall’emergenza di alcune sorgenti di acqua dolce. negli sprofondamenti presenti nell’area in esame si possono distinguere doline di crollo localmente chiamate canetre, impostate esclusivamente sui versanti di m.te paterno e sinkholes localizzati nelle coperture config 2 schema dell’ubicazione dei sinkholes nella piana di s. vitorino (rieti) scheme of the sinkholes in the s. vittorino plane (rieticentral italy) s. nisio tinentali della piana. per qualche autore (nolasco, 1998) alcune cavità di antica origine (lago di paterno, pozzo di mezzo e pozzo burino) rappresenterebbero delle doline. ma lo spessore dei depositi continentali posti al di sopra del substrato carbonatico e per la locale situazione geologico-strutturale queste depressioni si sarebbero comunque originate per fenomeni di risalita, di sifonamento ed erosione (piping) e rappresenterebbero dunque sinkholes in senso stretto (nel senso sopra indicato) (fig. 3). per altri autori (capelli et al., 2000; bersani & castellani, 2002) la genesi degli sprofondamenti nella piana di s. vittorino sarebbe legata alla dissoluzione e conseguente collasso di orizzonti di travertino, con spessori non superiori a 10 m, riscontrati in sondaggi a profondità di 7-8 m nei pressi di cotilia e a 3040 m in altre località. ma in altri sondaggi effettuati al centro della piana i travertini sono caratterizzati da spessori molto modesti e da una struttura sabbiosa, piuttosto incoerente, tale da non giustificare collassi di una certa entità. nei pressi poi del lago rotondo, verso le aree più meridionali della piana, non si sono incontrati travertini se non in spessori decimetrici. di conseguenza la sola presenza dei travertini peraltro non continui in tutta la piana, non è sufficiente a spiegare la genesi di tutte le cavità presenti nella piana stessa (fig 4). ma la disposizione degli sprofondamenti, tutti localizzati su allineamenti tettonici, la presenza sia di un acquifero confinato in profondità, sia di falde circolanti nelle coperture alluvionali, nonché la disposizione delle anomalie dei fluidi gassosi (faccenna et al., 1993; ciotoli et al., 1998, 2000, centamore & nisio, 2000) mettono in evidenza che fattore importante della genesi degli sprofondamenti in parola sono anche i processi di piping o suffosione legati ai fenomeni di dissoluzione degli orizzonti travertinosi, dove questi sono presenti (fig 4). questi fenomeni potrebbero essere stati favoriti, oltre che dai sistemi di dislocazioni, che costituiscono la via preferenziale di risalita dei fluidi, anche dalla presenza in profondità di un substrato carsificato in precedenza, le cui forme potrebbero essersi evolute in questo contesto, favorendo così le evidenze superficiali. i fenomeni di sifonamento che si produrrebbero nella parte più superficiale del manto alluvionale potrebbero avvenire in corrispondenza di più ampie cavità carsiche poste ad un centinaio di metri nel substrato carbonatico e in collegamento tramite lo sviluppato reticolo di faglie e fratture che si rinviene lungo tutta le piana. 22)) ppiiaannuurraa ppoonnttiinnaa ((llaattiinnaa)) casi di sprofondamento sono comuni in tutta la pianura pontina, costellata da numerosi laghetti e sorgenti; i laghi del vescovo, per esempio, sono una serie di cavità ubicate nell'area compresa tra il settore più meridionale dei monti lepini e il fiume uffente a sud di sezze, a ridosso di faglie di importanza regionale, che ospitano specchi d’acqua. da nord verso sud si riconoscono il lago di s. carlo, il gruppo vero e proprio denominato del vescovo e il lago mazzocchio. il gruppo del vescovo è composto da 4 specchi d'acqua, di cui 3 presentano acque mineralizzate (con presenza di alti tenori in co2, h2s e altri composti dello zolfo) e sono caratterizzati da colore opalescente, mentre uno è d'acqua dolce. quello d'acqua dolce è profondo circa 18 metri ed ha una caratteristica forma di 8. il lago 127 fig. 3 formazione di sinkholes nella piana di s. vittorino formation of sinkholes in the st. vittorino plain (rieti-central italy) i fenomeni di sprofondamento ... mazzocchio è invece alimentato dalle acque di un canale (che drena nel fiume uffente) dopo un impianto idrovoro, risulta circondato da alti canneti e difficile da reperire. doganella di ninfa, doganella di ninfa è ubicata nella porzione nordorientale della pianura pontina a pochi chilometri da latina. in questo settore la pianura pontina è bordata ad oriente dalla dorsale dei monti lepini, disposta in direzione appenninica, costituita da una potente successione di calcari di piattaforma. una faglia di importanza regionale borda il versante sud-occidentale dei monti lepini a contatto con la pianura, il substrato carbonatico viene ribassato a gradinata da un sistema di faglie (semigraben) al di sotto dei sedimenti alluvionali. in questa zona sono ospitate numerose emergenze per una portata complessiva di 15.000 l/s alimentate dall’acquifero principale ospitato nella dorsale lepina (boni et al., 1980; celico, 1983). al di sotto della pianura pontina i carbonati ribassati e chiusi al tetto dalle alluvioni prevalentemente limose costituiscono un acquifero imprigionato. a volte si riscontrano falde all’interno dei sedimenti continentali, alimentate sia da apporti meteorici sia dalla dorsale carbonatica attraverso una serie di faglie o fratture che mettono in comunicazione i due sistemi. lo sprofondamento a doganella è avvenuto il 22 agosto del 1989, in seguito ad una scossa sismica registrata nei primi giorni di agosto, e ad un periodo di siccità che ha provocato l’abbassamento della falda. la cavità passò da uno a 4 metri di diametro in soli tre giorni, per arrivare a 31 m tre anni dopo. attualmente è sede di un laghetto che assume forma ellissoidale con una superficie di 720 mq ed asse principale di 32 m. da dati recenti è stata ipotizzata la presenza a 30-40 m di profondità di travertini (bono, 1995; di filippo et al., 2002) e di alcuni deficit di massa (probabili cavità sotterranee) riscontrati da analisi gravimetriche, accompagnati ad una rete di canali e di fratture che possano provocare fenomeni di risalita, di dissoluzione e conseguentemente di erosione ed asportazione di materiale clastico con successivo collasso superficiale. tale situazione sembra molto simile a ciò che si verifica nella piana di s. vittorino. 33)) llaa vvaallllee ddeell tteevveerree ((ccaappeennaa)) nel settore nord-orientale dell’area vulcanica dei monti sabatini, in prossimità della valle del tevere, a sud del monte soratte, sono presenti forme di sprofondamento originatesi in epoca storica: lago vecchio (o lago sinibaldi), lago nuovo, fontana ciocci, lago puzzo. lago puzzo nell’area in esame dal punto di vista geologico si possono distinguere: un substrato meso-cenozoico del monte soratte e del monte belvedere, costituito dalla successione marina condensata calcareo-silico-marnosa; una successione marina, trasgressiva sul basamento carbonatico, costituta da alternanze di sabbie, argille e 128 fig 4 schema evolutivo di un meccanismo di piping sinkhole. a) caso con depositi alluvionali privi di orizzonti di travertino; b) l’orizzonte di travertino funge da struttura metastabile e permette l’allargamento di una cavità. evolutionary outline of a mechanism of piping sinkhole. a) case with alluvial sediments without horizons of travertine; b) the horizon of travertine acts as from meta-stabile structure and allows to the increase of one cavity. s. nisio ghiaie; una copertura vulcanica costituita da piroclastiti rimaneggiate alternate ad epivulcaniti; depositi lacustri con caratteristiche e granulometrie differenti in cui si intercalano diatomiti, travertini intercalati ai prodotti piroclastici. il monte soratte è un horst costituito da due scaglie tettoniche con piani di accavallamento a direzione nnw-sse; esso è delimitato a sud da faglie a direzione meridiana. da tali piani di faglia avviene la risalita di fluidi di origine profonda ricchi di gas; lungo il fosso s. martino si allineano una serie di sorgenti di portata modesta. le acque del lago puzzo in particolare hanno riscontrato un alto tenore di h2s, da cui il nome al lago. il basamento carbonatico al di sotto del lago si attesterebbe ad una profondità compresa tra i 50 ei 100 m; al tetto sono presenti sedimenti costituiti da sabbie, silt e piroclastiti. il lago puzzo, ormai in via di estinzione, si apriva a contatto tra i travertini (sponda sud con spessore di 67 m; di loreto et al., 1999) e le sabbie marine, presenta forma ellittica con asse maggiore orientato in direzione n-s, con profondità molto scarsa (mezzo metro) negli anni ’90, attualmente quasi del tutto interrito a causa degli apporti detritici. dal fondo del lago si originavano sorgenti mineralizzate, ormai completamente obliterate dalla copertura argillosa, ed emissioni di gas che si notano tuttora nei fanghi del fondo. la prima segnalazione storica della formazione del lago puzzo risale al 1856 (28 ottobre), quando si aprì improvvisamente una cavità che subito si riempì d’acqua (ponzi, 1857; ratti, 1857); essa venne attribuita a un fenomeno postvulcanico o al crollo di cavità carsiche. prevalse la seconda ipotesi con cui si spiegò anche la formazione di una seconda cavità, il lago di leprignano, che si formò nel 1895 (brunialti, 1895; folghraiter, 1896; meli, 1896; moderni 1896). altri laghi e piccole cavità ormai estinti si allineano tutti secondo una dislocazione ad andamento n-s; l’estinzione sembra esser proceduta da n verso s: (lago vecchio o lago sinibaldi, con diametro di 500 m, fontana ciocci (250 m), lago nuovo o di leprignano (260 m), pian della casa che si formò nel 1897. nel corso del tempo il lago puzzo si è colmato per apporti detritici provenienti dal vicino torrente di s. martino e si sarebbe riformato nella medesima posizione in tempi più recenti del 1930 accompagnato da emissioni di gas, lanci di detriti, boati (segre, 1948, patrizi, 1967). aallttrrii eesseemmppii nneellll’’aappppeennnniinnoo cceennttrraallee ttoossccaannaa 1) camaiore località le funi: il sinkhole si è formato il 15 ottobre del 1995 con 30 m di diametro e 11 di profondità (buchignani, 2002; buchignani & chines, 2002; d’amato et al., 2002; gonnelli et al., 2002). il substrato risulta costituito da calcare cavernoso affiorante ad una profondità media di circa 140 m, sormontato da alluvioni impermeabili o semipermeabili, con presenza di una potente falda in un acquifero confinato; 2) grosseto, località bottegone: il sinkhole si è formato il 29 gennaio1999 con 153 m di diametro e 17 di profondità (berti et al., 2001; gonnelli et al., 2002), il substrato risulta costituito da calcare cavernoso ad una profondità di circa 200 m, su cui giacciono argille e limi argillosi (in sondaggio riscontrati fino a 110 m di profondità, berti et al., 2002), con presenza di una potente falda di un acquifero confinato termale, nelle vicinanze di una faglia di importanza regionale; 3) lago di s. antonio, poggibonsi (siena), solo da notizie storiche (del zanna, 1901), di genesi incerta, si riescono a trarre informazioni di questo sprofondamento che potrebbe trattarsi di un sinkhole, formato su di un substrato di travertino, posto a non elevate profondità; 4) lago dell’accesa, massa marittima (gr) e lago di s. floriano, capalbio (gr), di origine incerta, si sono formati in base a notizie storiche alla fine del secolo scorso in seguito ad eventi improvvisi, su di un substrato carbonatico a notevole profondità sormontato da depositi continentali. ccoonncclluussiioonnii i casi di sinkhole in italia centrale, concentrati soprattutto nelle piane alluvionali, nelle immediate vicinanze di dorsali carbonatiche, presentano dimensioni diverse da poche decine di metri a diametri e profondità che possono superare i 100 m. in letteratura vengono definiti impropriamente sinkholes fenomeni la cui genesi coincide con le doline di crollo, le doline alluvionali o le doline di subsidenza in roccia. molti autori definiscono sinkhole una cavità di qualsiasi forma che si genera anche per cause antropiche, così come crolli di volte in antiche catacombe, o in miniere dismesse, cave di tufo o crolli del manto stradale sovrapposto a cavità. in questa sede si vuole puntualizzare la differenza tra il fenomeno di sprofondamento in genere, di cui fanno parte tutti i fenomeni sopra elencati, le doline ed i sinkholes. i sinkholes (il cui termine corretto in italiano è camini di collasso) hanno forma sub-circolare e si aprono improvvisamente in terreni di origine continentale a granulometria variabile. la genesi di un fenomeno con queste caratteristiche non è semplicemente carsica (come avviene nelle doline) ma deve necessariamente ammettere un processo di risalita di acque, ricche in gas, che possano generare sifonamento e asportazione di particelle solide, suffosione o piping sfruttando come vie di risalita preferenziali sistemi di faglie e fratture. fenomeni di questo tipo, definiti in questa sede sinkhole in senso stretto, coincidono con quei fenomeni definiti dalla letteratura anglosassone piping sinkhole. pertanto allo stato attuale delle conoscenze poiché non è più possibile ridefinire il termine sinkhole in tutta la letteratura internazionale risulta necessario aggiungere al termine, almeno, un attributo che chiarifichi la genesi e il tipo di fenomeno di cui si sta trattando (piping sinkhole, collapse sinkhole, solution sinkhole e così via). tutti i casi esaminati nell’appennino centrale presentano caratteristiche comuni: 129i fenomeni di sprofondamento ... a) presenza di un substrato carbonatico posto a notevole profondità (oltre i 100 m), b) presenza al tetto del substrato un potente pacco di depositi continentali a granulometria variabile, generalmente impermeabili o semipermeabili c) scarse caratteristiche fisico-meccaniche dei sedimenti di tetto (scarsa, consistenza o uno scarso grado di addensamento); d) presenza di un potente acquifero confinato (falda in pressione) e di sorgenti poste nelle immediate vicinanze con portate elevate; e) origine tettonica delle piane sulle quali si originano i fenomeni (graben o semigraben); f) presenza di importanti dislocazioni tettoniche di faglie e di fratture che attraversano il substrato; g) presenza di gas (radon, metano, elio, anidride carbonica, acido solfidrico); h) presenza di un reticolo di piccole fratture o diaclasi che mette in comunicazione il mezzo permeabile con quello impermeabile. non comune a tutti i casi (piana pontina?, alcuni casi nella piana di s. vittorino?, lago di s. antonio) è la presenza di orizzonti o lenti travertinose poste a profondità intermedia tra il substrato e il piano campagna (3040 m). gli autori che hanno analizzato il problema (ad esempio capelli et al., 2000; bersani & castellano, 2002) manifestano diversità di vedute sulla possibilità di un processo di risalita di fluidi, sifonamento e suffosione su sedimenti continentali di notevole potenza. tale possibilità sembra invece poter dipendere dagli altri elementi sopra elencati, in particolare i meccanismi di piping e suffosione potrebbero sfruttare proprio le linee di maggior debolezza, nonché dal fattore tempo. pertanto i fenomeni di erosione sub-superficiale potrebbero essere richiamati dal basso ed essere collegati ai fenomeni carsici del bedrock attraverso linee tettoniche e fratture. in alcuni casi è possibile che le cavità di superficie possano avere origine per la dissoluzione di sedimenti, quali travertini o altri, a scarse profondità (alcuni metri o poche decine di metri) dal piano di campagna, in molti altri casi la genesi dei sinkholes è da ricercarsi a profondità più elevate nel bedrock carbonatico. bbiibblliiooggrraaffiiaa anelli f. (1959) nomenclatura italiana dei fenomeni carsici. grotte d’italia, 3(3), 3-56, castellana grotte. anelli f. (1965) fenomeni carsici, paracarsici e pseudocarsici. giorn. di geol., 3311(2), 11-35. beck b.f. (1984) sinkholes: their geology, engineering & environmental impact. ed. a.a. balkema/ rotterdam/boston (1984). beck b.f. & wilson w.l. (1987) karst hydrogeology: engineering and environmental applications. ed. a.a. balkema/rotterdam/boston (1987). bersani p. & castellano f. (2002) i sinkhole della piana di s. vittorino (rieti) e il rischio idraulico connesso. in: le voragini catastrofiche, un nuovo problema per la toscana. att. conv. 31 marzo 2000, (gr). regione toscana, 47-61. bersani p., biagi p. f., ferranti c. & piotti a. (2000) gli sprofondamenti della piana di s. vittorino (rieti). l’aquila, 1/2000, 39-48. berti g., canuti p., & casagli n. 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(1996) new sinkhole data spreadsheet manual (v1,1) subsurface evaluation inc., tampa, florida, 31 pp. 132 ms. ricevuto il 2 dicembre 2002 testo definitivo ricevuto il 13 maggio 2003 ms. received: december 2, 2002 final text received: may 13, 2003 s. nisio imp.palombo biochronology of plio-pleistocene mammalian faunas on the italian peninsula: knowledge, problems and perspectives maria rita palombo dipartimento di scienze della terra, università "la sapienza cnristituto di geologia ambientale e geoingegneria piazzale a. moro, 5 i-00185 roma, italy <mariarita.palombo@uniroma1.it> abstract: palombo m.r., biochronology of plio-pleistocene mammalian faunas on the italian peninsula: knowledge, problems and perspectives. it issn 0394-335, 2004 the biochronological setting thus far proposed for mammalian faunas from the italian peninsula (constructed on the basis of classic criteria: the absence/presence of particular taxa, faunal turnovers, the “evolutionary stage” of taxa belonging to a well-defined phyletic lineage or “typical taxa associations”) provides a highly-detailed categorization of italian assemblages. nevertheless, the more detailed the bioevent sequence becomes, the more difficult it is to establish correlations on a larger scale. multivariate analysis (the recognition of successive, non-overlapping, ecologically-adjusted assemblages of taxa living together in a given space and time) may provide a useful tool for defining faunal complexes having broader biochronological significance. as far as middle pliocenemiddle pleistocene large mammalian faunas from the italian peninsula are concerned, on the basis of our results, we operationally consider the following complexes as possible high-rank biochrons: villafranchian+ early galerian (middle, late pliocene +early pleistocene local faunal assemblages) = “archaic faunas complex ” (afc), and middle, late galerian+early aurelian (middle pleistocene) = “modern faunal complex” (mfc). moreover, the following groups may be regarded as possible lower-rank biochrons: i = early villafranchian; ii = middle villafranchian + late villafranchian; iii = latest villafranchian + early galerian; iv = middle and late galerian; v = early aurelian. the separation between the two main clusters highlights the faunal renewal occurring during the latest early pleistocene, as confirmed by mammalian species turnover and richness trends. the important reorganization of faunal complexes, characterising the transition from the late villafranchian plus early galerian (early pleistocene) to the middle-late galerian plus early aurelian (middle pleistocene) mammalian faunas, can be linked to worsening climate during the last part of the early pleistocene (from about 1.1 to about 0.8 ma). this evidence encourages reconsideration of the definition of galerian land mammal age (lma) previously proposed for italian mammalian faunas. the definition of biochronology (the method most widely-applied to the terrestrial realm in order to relate biological events to the geological time scale), whose application has often been tainted by reference to and inference from biostratigraphy, is briefly reconsidered. riassunto: palombo m.r., biocronologia dei complessi faunistici a grandi mammiferi del plio-pleistocene della penisola italiana: problemi, conoscenze, prospettive. it issn 0394-3356, 2004. l’assetto biocronologico fin ad ora proposto per i complessi a grandi mammiferi dalla penisola italiana si base essenzialmente su bioeventi di comparsa e scomparsa e quindi sui classici criteri di assenza/presenza di definiti taxa, rinnovi faunistici, “grado evolutivo” di taxa appartenenti a ben definite linee filetiche, riconoscimento di “associazioni tipiche”. gli schemi attualmente in uso forniscono una scansione biocronologici dettagliata dei complessi faunistici italiani, tuttavia, quanto maggiore è la quantità di dati di nuovo acquisizione e quanto più dettagliata diviene la sequenza bioeventi riconosciuti, tanto più difficile risulta operare correlazioni a grande scala. le analisi multivariate (finalizzate alla definizione di “gruppi” di faune locali tra loro ben discriminabili, ciascuno dei quali costituente un insieme di taxa presumibilmente vissuti in uno stesso intervallo temporale in definite aree geografiche, coerente dal punto di vista ecologico) possono fornire un mezzo utile di indagine per una prima definizione di complessi faunistici che abbiano una più ampia valenza biocronologica. i risultati ottenuti per complessi faunistici a grandi mammiferi della penisola italiana dal pliocene medio al pleistocene medio, con analisi di somiglianza e di ordinamento dei beventi, suggeriscono di considerare quali biocroni di più alto rango due complessi faunistici: il complesso “ villafranchiano + galeriano inferiore” (local faunal assemblages, lfas, del pliocene medio e superiore e del pleistocene inferiore), qui denominato “complesso faunistico arcaico” (afc), e il complesso “galerian medio e superiore + aurelian inferiore” (lfas del pleistocene medio), qui denominato “complesso faunistico moderno” (mfc). inoltre, possono essere considerati quali possibili biocroni di rango inferiore i seguenti gruppi: i = villafranchiano inferiore; ii = villafranchiano medio + villafranchiano superiore; iii = tardo villafranchiano superiore + galeriano inferiore; iv = galeriano medio e superiore; v = aureliano inferiore. la separazione fra i due gruppi principali evidenzia il profondo rinnovamento faunistico che si realizza alla fine del pleistocene inferiore. la riorganizzazione dei complessi a grandi mammiferi, che caratterizza la transizione tra il complesso che riunisce le lfas del tardo villafranchiano e del galeriano inferiore (pleistocene inferiore) e quello delle lfas del galeriano medio, superiore e dell’aureliano inferiore (pleistocene medio), può essere correlata con il deterioramento climatico del tardo pleistocene inferiore (da circa 1,1 a circa 0,8 ma). su queste basi, sembrerebbe, quindi, auspicabile una ridefinizione dell’età a mammiferi (land mammal age, lma) ” galeriano”, come a suo tempo proposta per le faune a mammiferi della penisola italiana. vengono anche brevemente discussi la definizione di biocronologia ed i suoi criteri di applicazione. keywords: biochronology, pliocene, pleistocene, large mammals, italy. parole chiave: biocronologia, pliocene, pleistocene, grandi mammiferi, italia. il quaternario italian journal of quaternary sciences 17(2/2), 2004, 565-582 566 m.r. palombo 1. foreword as claimed by lindsay (2003), chronostratigraphy (the method generally applied to the oceanographicmarine realm) and biochronology (that most commonly applied to the terrestrial realm), are the prime conceptual methods for relating biological events to the geological time scale. nevertheless, to date, the organisation of geological time on the basis of evidence supplied by continental mammal faunas has continued to be a field plagued by interpretative and semantic confusion. the divergence of opinions on biostratigraphic/biochronological matters may often be attributed to interference between operational (based on stratigraphic records like biostratigraphy) and theoretical (based on bioevents linked to taxa evolution and palaeocommunity transformation biochronology) methodological approaches (see e.g. tedford, 1970; mein 1975, 1990, 1998; woodburne, 1977, 1987, 1996; berggren and van couvering, 1978; guerin, 1982, 1990; de giuli et al., 1983; daams & freudenthal, 1981; flynn et al., 1984; lindsay, 1985, 1997, 2001, 2003; archibald et al., 1987; emry et al., 1987; krishtralka et al., 1987; lindsay & tedford, 1990; pickford, 1990; fernandez-lopez, 1991; brujin et al., 1992; lister, 1992; lucas, 1992; salvador, 1994; berggren et al., 1995a, 1995b; prothero, 1995; opdyke et al., 1997; sen, 1997; van dam, 1997, 2001, 2003; daams et al., 1998; fejfar et al., 1998; walsh, 1998; agusti et al., 2001; azanza et al., 2002; koufos, 2003; ravazzi, 2003 etc). moreover, even if biochronology is a fundamental tool in correlating terrestrial deposits, “biochronology has never been discussed in any stratigraphic code because of that loose and ambiguous application” (lindsay, 2003 p.216). however, it is worth noting that a biochronological unit is a time span defined by palaeobiological events, while a biostratigraphic unit is a body of rock strata defined by its fossil content (stratigraphic datum) (schoch, 1989; salvador, 1994). indeed, discontinuity in the continental sedimentary record, the rarity of deposits formed in a regime of virtually continuous sedimentation, the anisotropy of palaeoenvironmental conditions and taphonomic and sampling biases are responsible for the fact that the stratigraphic order of the highest and lowest occurrences (stratigraphic datum) of taxa remains within a given geographical area does not necessarily reflect the temporal order of their actual first/last appearances (palaeobiological events) in time. therefore, as far as large continental mammals are concerned, given that: 1) the actual occurrence in time of a palaeobiological entity (both in general or in a given geographical area) cannot be unquestionably established by its fossil evidence; 2) the relative or absolute deposition dates for rock-bodies in which the first/oldest and last/youngest local appearances of fossil remains (lowest and highest stratigraphic records) are documented, respectively correspond only to the “ante quem” or “post quem” time of actual origination and extinction bioevents; 3) boundaries (specific surfaces within a sequence of rock strata selected as the standard for defining and recognising biostratigraphic units, salvador, 1994) are not indicative “because of the impossibility of defining them with precision” (gliozzi et al., 1997, p.369) and “biozones” ( “bodies of rock strata that are defined or characterised on the basis of their contained fossils”, salvador, 1994, pag. 53) cannot be defined, even if “biochrons” have previously been regarded as similar to “concurrent range” or “assemblage” zones (gliozzi et al., 1997). ultimately, biochronology can be defined as “ the organization of geologic time according to the irreversible process of organic evolution” (lindsay, 2003). “biochrons” represent lapses of time during which faunas demonstrate clear taxonomic homogeneity (see also alberdi et al., 1997); from an operational point of view, they might be considered as “blocks of coordinated stasis” (brett et al., 1996) during which no turnover is expected. faunal complexes belonging to biochrons may be regarded as nonoverlapping and " ecologically adjusted groups of animals with specific geographic limits and chronologic range" (tedford, 1970, pag. 602). nonetheless, if on the one hand first/last appearance bioevents (palaeobiological events on which biochronology is based) have been the principal basis for establishing the chronological setting of continental mammalian faunas, on the other hand these bioevents are documented by the lowest/highest occurrences of fossil remains in fossiliferous levels of various continental stratigraphic successions (stratigraphic datum, the basis of biostratigraphy). indeed, mammalian paleontostratigraphy (sensu walsh, 1998) is actually founded on fossil records available in continental rocks, and new discoveries can substantially alter pre-established biochronological schemes. the biochronological settings thus far proposed for mammal faunas on the italian peninsula have been based on the faunal complexes named faunal units (fus), further classified in a number of land mammal ages (lmas). the definition of fus derives from bioevents, such as the first appearance of one or more taxa, and/or the possible disappearance of others on the evolutionary stage, displayed by taxa belonging to a well-established phyletic lineage, or on typical taxa associations. this substantially agrees with lindsay’s definition (2003) for lmas, defined as relatively short intervals of geologic time that can be recognized and distinguished from earlier and later units (in a given region or province) by a characterising assemblage of mammals. since initial introduction of these biochrons (azzaroli, 1977), italian palaeontologists have proposed some new fus and/or new mammal ages (mas) or revised others (see e.g. torre, 1987; sala et al., 1992; caloi & palombo, 1996; gliozzi et al., 1997; petronio & sardella, 1999; palombo et al, 2004). the introduction of such new biochrons often depends on acquiring new data and discovering new fossiliferous assemblages that enable better discrimination of the temporal succession of bioevents by means of the highest and lowest occurrences in local sedimentary sequences. indeed, the complex physiography of the italian peninsula, the geographical and ecological barriers represented by the alpine and apennine chains, together with its remarkable latitudinal rather than longitudinal extension, as well as the great influence of the mediterranean sea on climatic conditions, supply a unique opportunity to analyse the influence of various factors influencing the structure of mammal assemblages in the course of time. it is thus evident that the current biochronological scheme provides very detailed resolution for italian assemblages, but is less useful for comparing and correlating other european mammal faunas. the aim of this paper is: 1) to provide a concise picture of our knowledge of biochronology of italian large mammals; 2) to update previous biochronological schemes in light of the latest discoveries; 3) to define adjusted homogeneous groups of taxa having biochronological significance using multivariate analyses; 4) to compare these “groups” with previously-established biochrons. 2. biochronological framework: an overview to define the chronological framework of italian mammal faunas, a number of schemes have been proposed by several authors (for instance ambrosetti et al., 1972; azzaroli, 1977, 1982, 1983, 1991; de giuli et al, 1983; torre, 1987; azzaroli et al., 1988; torre et al., 1992, 1996; caloi & palombo, 1990, 1996; gliozzi et al., 1997; petronio & sardella, 1999). initially, azzaroli (1977) proposed a subdivision of six fus for mammal faunas belonging to the villafranchian lma. subsequently, the discovery of new faunas, adding to knowledge of faunal renewal phases and the transitional character of some local assemblages (lfa), led to the introduction of new faunal units and/or new proposed mammal ages. in 1997, gliozzi et al. suggested a biochronological scheme for middle pliocene to late pleistocene italian continental faunas (large and small mammals, fresh-water molluscs and brackish ostracods) that has recently been widely utilised by italian palaeontologists. three lmas were defined for the time span between the middle pliocene and late pleistocene: villafranchian (late middle pliocene to early early pleistocene), galerian (late early pleistocene to early middle pleistocene), and aurelian (late middle pleistocene to late pleistocene), respectively including eight (triversa, montopoli, saint vallier, costa san giacomo, olivola, tasso, farneta, pirro), four (colle curti, slivia, isernia, fontana ranuccio) and more than two fus (torre in pietra, vitinia and non-defined). moreover, the transitional character of some local faunas was pointed out (see discussion in gliozzi et al., 1997). subsequently, petronio & sardella (1999) proposed ponte galeria local fauna as representative of a distinct middle galerian fu, transitional to isernia fu. 2.1 the villafranchian land mammal age (lma) the villafranchian was originally defined as an age/stage, since pareto (1865) designated the lower boundary of the villafranchian stratotype in villafranca d’asti (italy) at the bottom of the vertebrate bearing fluvio-lacustrine sequence overlying pliocene marine beds. subsequently, the “villafranchian” question has been extensively debated (see carraro, 1996 for a review and discussion). however, subsequent authors considered the villafranchian as a biochron/biochronozone defined by dispersal events, and not as a geochron/geochronozone, formally defined by golden spikes. for example, heintz (1970) considered the villafranchian as a biochron including the middle and late pliocene. this french scientist divided his 567biochronology of the ... villafranchian into four biochrons (early, middle, late and latest villafranchian) on the basis of taxa belonging to phyletic lines of cervid taxa. on the other hand, azzaroli (1977) extended the villafranchian to the earlymiddle pleistocene boundary. more recently, gliozzi et al. (1997) considered the villafranchian ma a biochron beginning with faunal turnover marked by the appearance of newcomers such as “pseudodama”(= axis according to di stefano & petronio, 2003), leptobos stenometopon, and stephanorhinus elatus (=s. jeanvireti), and ending before the jaramillo subchron. 2.1.1 early and middlevillafranchian fus based on faunal renewals, the villafranchian lma was divided into early, middle and late sub-biochrons (azzaroli et al., 1988; gliozzi et al., 1997). the early villafranchian is represented by the triversa fu, established on a number of local faunas from the villafranca d’asti area (piedmont) and from central italy (e.g. lower and upper valdarno, arcille, spoleto). palaeomagnetic analysis at fornace r.d.b. (villafranca d’asti) ascribes the sequence to gauss chron (lindsay et al., 1980). nevertheless, according to lindsay et al. (1995), the intervals of reversed magnetic polarity separated by a normal magnetozone previously identified at fornace r.d.b. cannot be correlated with the mammoth or khaena episodes, but with the late gilbert chron. nevertheless, this hypothesis disagrees with geological palynological evidence (albianelli et al., 1995,1997; bertini & roion, 1997) as well as with the paleomagnetic calibration (torre et al. 1996) carried out on a long sedimentary sequence containing typical early villafranchian fossil assemblages appearing at the santa barbara quarry (lignitic lacustrine silty clays and sands, meleto clays from the castelnuovo dei sabbioni sequence, upper valdarno). the results attest a long normal polarity interval interrupted a few meters above the fossiliferous lignite level by a reversed polarity interval, respectively attributable to the late gauss age and the short kaena event. consequently, the beginning of the early villafranchian can be dated at about 3.3-3.2 ma. b.p. the triversa faunal complex (table 1), although renewed with respect to ruscinian faunas, maintained quite a damp forest character: pachyderms and smallmiddle sized ruscinian perrissodactyla and artiodactyla, mainly browsers or mixed-feeders inhabiting dense or clear woodland, were still present, along with arboreal omnivores such as ursus minimus. on the other hand, the disappearances of primates and carnivores inhabiting humid and forest environments, as well as the appearance of some taxa dwelling in more or less open environments, such as leptobos stenometopon, testified to moderate structural renewal, which can be correlated with the climatic cooling taking place at about 3.2/3.1 (palombo, 2004). the following montopoli fu is based on the rich fauna from a site near montopoli (lower valdarno), found in a fossiliferous level at the top of a marine sequence, calibrated with the gauss/matuyama transition (lindsay et al., 1980). the montopoli local faunal assemblage (lfa), (dated to about 2.6 ma), as well as the montopoli f. u., have long been considered early villafranchian in age. nevertheless, the noticeable faunal turnover characterising the transition from the 568 m.r. palombo table 1 biochronology of selected large mammals of the italian peninsula, dating from the late pliocene to the late pleistocene. distribuzione cronologica dei principali taxa di grandi mammiferi della penisola italiana dal pliocene medio al pleistocene superiore 569 triversa f.u to the montopoli f.u, delineated by the cooling event taking place about 2.6/2.5 ma, may be regarded as a bioevent marking the beginning of the middle villafranchian (alberdi et al., 1998, caloi & palombo 1999, palombo 1995, 2004, palombo et al., 2003). the reorganization of "palaeocommunities” from the early to middle villafranchian (the so-called “elephant-equus event” sensu lindsay et al., 1980), corresponds to a true turnover and can be regarded as the starting point of a dispersal phase. in the montopoli fu, forest taxa greatly diminished and several new herbivores appeared, including large-sized ones and pachyderms, such as a primitive mammuthus (see palombo & ferretti, 2005 for a discussion). moreover, the occurrence of the large equus livenzovensis was consistent with the increasing extension of grassy areas, characterised by herbaceous vegetation of the steppe type, suggesting arid conditions (suc et al. 1995; torre et al. 2001; palombo, 2004). italian faunal assemblages belonging to the middle villafranchian (“saint vallier” fu) are scanty, with weak stratigraphic constraints. for example, the colle pardo lfa (anagni basin, cassoli & segre naldini, 2000), despite the scarcity of faunal remains, has been considered intermediate in age between the montopoli and costa san giacomo complexes by several authors (caloi & palombo, 1996; gliozzi et al., 1997). according to the faunal list, only the occurrence of a caprinae (possibly similar to hemitragus orientalis recorded at the late pliocene bulgarian site of slivnitsa, cregutbonnoeur & spassov, 2003) might exclude attribution to an older faunal complex (?montopoli fu). consequently, using only large mammals, a faunal complex characterising the “saint vallier” fu cannot be adequately defined in italy, unless running through taxa are considered. in the following costa san giacomo fu, a dog, similar to the late villafranchian species canis etruscus, and sus strozzii were first recorded (costa san giacomo lfa, anagni basin, biddittu et al. 1979). moreover, typical middle villafranchian taxa, such as “pseudodama” lyra (axis lyra, according to di stefano & petronio, 2003), eucladoceros tegulensis, leptobos merlai, gazella borbonica and gazellospira torticornis were still present, along with the ruscinianmiddle villafranchian taxon anancus arvernensis1. the diffusion of the genus canis in europe, the so called “wolf event” (sensu azzaroli, 1983) [canis sp. is also recorded at chilhac (monguillon-douillet, 2000), a site dating more than 1.9 ma (bœuf, 1997)], possibly a more gradual phenomenon than previously supposed, crossed the plio-pleistocene boundary (sensu aguirre & pasini, 1985)2 and culminated at the beginning of the pleistocene, at the time of the tasso fu. 2.1.2 the beginning of the late villafranchian the faunal renewal taking place at the end of the late pliocene involved both carnivore and herbivore guilds, which clearly became more diversified. most pliocene species disappeared, particularly among herbivores, and new carnivores and herbivores progressively spread across the italian peninsula (table 1). thus this renewal may be regarded as an increasing dispersal phase rather than an actual turnover (palombo, 2004). according to azzaroli (1977), three fus (olivola, tasso and farneta) belong to the late villafranchian, at that time considered to coincide with the early pleistocene. subsequently, a fourth fu, pirro, more advanced than farneta, was added (caloi & palombo, 1996), and the end of the late villafranchian was later brought forward, before the jaramillo subcrhon (gliozzi et al., 1997). the lfa from olivola (val di magra) is characterised by the lowest occurrence of pachicrocuta brevirostris, panthera gombazsoegensis, ”pseudodama” nestii (axis nestii according to di stefano & petronio, 2003) and eucladoceros dicranios; scanty remains of procamptoceras brivatense were also found, whereas canis etruscus was represented by several individuals. two late villafranchian lfas, matassino and casa frata, were retrieved from the upper valdarno, from fossiliferous levels cropping out along the montevarchi sequence (borselli et al., 1980; de giuli & masini, 1987). matassino and casa frata lfas were ascribed respectively to olivola and tasso fus (azzaroli et al., 1988; but see gliozzi et al, 1997), due the occurrence of new taxa such as lycaon falconeri (see martinez navarro & rook, 2003, for a discussion) at casa frata, equus stehlini,? lepobos vallisarni and praeovibos sp. moreover, matassino and casa frata lfas have been respectively calibrated with the β event and with the top of the olduvai subchron (torre et al., 1996). recently, a new faunal assemblage was collected at poggio rosso, in sediments of the second deposition phase called the montevarchi succession (argille del torrente ascione, albianelli et al., 1995; mazza et al. 2004), just below the plio-pleistocene boundary, but about 30 m above the matassino lfa (napoleone et al., 2001; napoleone & azzaroli, 2002; napoleone et al., 2003). the taxonomical composition of the poggio rosso lfa is “intermediate” between that of olivola and tasso fus due to, for example, the occurrence of both canis arnensis and chasmaporthetes lunensis (mazzini et al., 2000; mazza et al., 2004). accordingly, on the basis of magnetostratigraphic calibration of the matassino and poggio rosso localities, the late villafranchian theoretically started during the latest pliocene, undoubtedly before the plio-pleistocene boundary. according to napoleone biochronology of the ... 1 it is worth noting that zanchetta & mazza (1996) proposed an early pleistocene age for a fragmentary skeleton of anancus from monte castello (lower valdarno); in any case, this datum requires confirmation. 2 the profuse changes in flora and fauna during this event have prompted several authors (alberdi et al 1997; suc et al. 1997; morrison & kukla, 1998 and references therein) to propose placing the plio-pleistocene boundary here. [we have to note that, as pointed out by kolfschoten & gibbard (1998, p. 16) “the fact that the vrica boundary was only notified by the moscow igc in 1984, should not be a reason for not reconsidering the boundary position”. thus, the lowering of the pliocene/pleistocene boundary to around the gauss/ matuyama palaeomagnetic reversal (mis 104, approximately 2.6 ma) is being debated by several authors, as well as the inqua commission of stratigraphy. in this paper, we provisionally maintain the plio-pleistocene boundary proposed by aguirre & pasini (1985), even if the global change occurring at mis 104 should be considered a more appropriate boundary. 570 et al. (2003, p. 308), faunas belonging to the olivola fu could be “inferred as pre-olduvaian, not younger than 2.0 ma.” moreover, it is worth noting that the structure of faunal complexes ascribed to olivola and tasso fus are not very dissimilar, the second differing essentially in the appearance of lycaon falconeri, leptobos vallisarni and equus stehlini, whereas gallogoral meneghinii and gazellospira torticornis were not recorded. moreover, the hippopotamus antiquus from valdarno, whose appearance was previously considered as belonging on the tasso fu, was probably retrieved from fossiliferous levels younger than those of the montervarchi succession (napoleone et al., 2003). accordingly, the olivola and tasso faunal complexes seem to express the same progressive faunal renewal culminating with the “tasso” faunal complex. consequently, the hypothesis that the olivola and tasso faunal complexes may represent a single fu cannot be definitively ruled out. 2.2 the end of the villafranchian lma and the dawn of the galerian lma during the following early pleistocene (“postgalerian” sensu caloi & palombo, 1996), most of the typical villafranchian taxa disappeared or became rare, and some new species, phylogenetically linked to taxa characterising early middle pleistocene faunas, progressively appeared. on the whole, during the early pleistocene (late villafranchian pro parte and early galerian), herbivores inhabiting open environments became more abundant, and forest dwellers noticeably reduced their diversity (table 1). this is consistent with the early pleistocene climatic trend, characterised by a progressive decrease in mean temperature, although climatic oscillations were not accentuated. moreover, several data suggest the spread of grassland/steppe areas (suc et al., 1995; bertini, 2000 and references therein). equus stenonis was replaced by the slenderlimbed equus altidens and by the heavier, larger equid already ascribed to the problematic group of equus bressanus/equus suessenbornensis. among pachyderms, rhinoceroses, perhaps linked to stephanorhinus hundsheimensis, seem to have been ecological substitutes for stephanorhinus etruscus. moreover, ovibovines, megalovis sp., and bison-like bovines appeared locally (bison (eobison) degiuli and perhaps another taxon (?bison sp.) may be linked to the more advanced middle galerian bison schoetensacki). nevertheless, forest areas were still rather abundant and, little by little, woodlands spread during more temperate and humid climatic phases. woodlands were mainly inhabited by cervids belonging to the small-medium sized species of the “pseudodama” genus and by the larger mixed-feeder “praemegaceros” obscurus3, which replaced the browser eucladoceros (table 1). furthermore, a number of data seem to confirm the transitional character of typical late villafranchian and galerian mammal assemblages (azzaroli et al., 1988, caloi & palombo, 1996; palombo, 2004 and references therein). according to gliozzi et al. (1997), the appearance of “praemegaceros” verticornis is the bioevent conventionally marking the beginning of the galerian lma (colle curti fu). the lowest species occurrences of this taxon in italy is in the colle curti lfa, calibrated with the jaramillo subchron (coltorti et al., 1998). however, colle curti lfa shares several taxa (carnivores, rhinoceros, hippopotamuses) with older lfas belonging to the pirro nord fu (table 1). thus, despite the appearance of “praemegaceros” verticornis as well as the innovative characteristics demonstrated by arvicolids from colle curti lfas (coltorti et al., 1998), early galerian lfas seem more closely related to the latest villafranchian faunas than to ensuing true galerian ones (palombo et al., 2003; palombo, 2004; palombo & valli, 2004). the end of the early pleistocene (end of the villafranchian event sensu azzaroli et al., 1988) actually represented the most significant period of striking faunal renewal on the italian peninsula, giving rise to remarkable palaeocommunity reorganization involving faunal migrations and extinction events (see alberdi et al. 1997, gliozzi et al. 1997; palombo, 2004; palombo et al., in press). 2.2.1 middle and late galerian faunal complexes the middle galerian (early middle pleistocene) came into being during great climatic cooling (stages 24 and 22 of the marine oxygen isotopic signal, mis) characterising the beginning of the middle pleistocene (sensu cita & castradori, 1995)4. faunal renewal derives from two distinct trends: 1) the progressive reduction in richness characterising late early pleistocene faunas (from farneta to colle curti fus), 2) the subsequent dispersal and progressive diffusion in italy of taxa from eastern and central europe, leading to an important and relatively rapid increase in diversity (slivia fu) (palombo, 2004). m.r. palombo 3 the name megaceroides (type species “cervus" algericus lydekker 1890) was proposed by joleaud in 1914, as a cervus subgenus for a fragmentary maxillary; subsequently, arambourg (1932, 1938) ascribed a skull from the late pleistocene of algeria and morocco to this species. similarities in skull features between specimens from the magreb and the megacerines (= megacerini tribus, sensu viret 1961) from europe, first pointed out by azzaroli (1952), have subsequently been widely debated (see e.g. hadjoudis, 1990; azzaroli & mazza, 1992; croitor, 2004; abbazzi, in prep.). all in all, it seems more correct to maintain the name megaceroides only for the north african species. nevertheless, the problem concerning the nomenclature of the genera referring to the tribe megacerini is still unresolved. assuming that the species ascribed to the so-called “verticornis” group and the “giganteus” group belong to two distinct lineages, what is the correct generic name among those used thus far for the giant deer belonging to the “verticornis” group and the “giganteus” group belong to two distinct lineages, what is the correct generic name among those used thus far for the giant deer belonging to the “verticornis” group? the name “praemegaceros”, though not formally correct (see e.g. azzaroli, 1979; caloi & palombo, 1996), has been frequently employed, whereas other names, such as “ortogonoceros” or “psekupsoceros”, have not been de facto utilised in more recent times. for this reason, to avoid additional confusion, we provisionally use the generic name “praemegaceros” for these giant european deer. 4 it is worth noting that the earlylate pleistocene boundary is currently placed informally at the matuyama/brunhes palaeomagnetic inversion (richmond 1996), but cita & castradori (1995) proposed a lower horizon at marine isotope stage (mis) 25. in the course of time (table 1), the appearances of several pachyderms (elephas (palaeoloxodon) antiquus, mammuthus trogontherii, stephanorhinus kirchbergensis, stephanorhinus hemitoechus), cervids (small-sized capreolus capreolus, medium-sized cervus elaphus and dama clactoniana, large-sized megaloceros savini and “praemegaceros” solilhacus) and large and middle-sized bovines (hemibos galerianus see martinez navarro & palombo 2004, for a discussion-, bos primigenius, ovis ammon antiqua and hemitragus bonali), brought about a major change in herbivore guilds. among carnivores, crocuta crocuta was surely recorded for the first time in the ponte galeria 2 lfa (sardella, 2004), whereas the lowest occurrence of some other large carnivores (active hunters that were both flesh-eaters and scavengers, such as ursus deningeri, panthera pardus, panthera leo fossilis, and “hyaena prisca”) was even later, in lfas belonging to the isernia fu. according to gliozzi et al. (1997), two fus, slivia a n d i s e r n i a , b e l o n g t o t h i s m a m m a l s u b l m a . subsequently, petronio & sardella (1999) proposed a new fu, ponte galeria fu, based on specimens found in hst deposits of the pg2 sedimentary sequence cropping out along the latium coast (= ponte galeria 2, see milli et al., 2004). the above-mentioned authors believed the age and taxonomical composition of the ponte galeria fu to be intermediate between the slivia and isernia lfas. if the three middle galerian fus were valid, they would differ essentially in the persistence of m i m o m y s s a v i n i , p a c h y c r o c u t a b r e v i r o s t r i s a n d panthera gombaszoegensis (slivia fu), the exclusive occurrence of hemibos galerianus (ponte galeria fu) and the appearance of bos primigenius (isernia fu). nevertheless, it is possible that slivia and ponte galeria 2 lfas belong to the same fu due to the uncertain identification of some herbivores from slivia local fauna, as well as limited knowledge of the carnivores and micromammals from the ponte galeria 2 lfa (palombo, 2004). moreover, an arvicolid similar to mimomys savini has recently been found in pagliare di sassa lfa (l’aquila, abruzzo) (palombo and di canzio, unpublished data) where “praemegaceros” verticornis, megaloceros savini (as in ponte galeria) and dama cf d. clactoniana were also recorded (palombo et al., 2001). as far as the transition from the middle (isernia fu) to the late galerian (fontana ranuccio fu) is concerned, we can place it around 500 ka, in view of the age proposed for the lfas ascribed to the isernia fu (notarchirico, estimated age about 600 ka, lefèvre & raynal 1999, lefèvre et al. 1999; isernia, estimated age about 600 ka; coltorti et al., 2000), and the possible age of the fontana ranuccio lfa (estimated age about 458 ka, biddittu et al. 1979). during the late middle galerian (fontana ranuccio fu), “villafranchian” taxa had not been recorded and the number of very large herbivores diminished (table 1), leaving the occurrence of “galerian” equids and megacerines in doubt. moreover, the specialised and slightly larger h. antiquus was replaced by hippopotamus amphibius and, among carnivores, ursus arctos appeared, as well as felis silvestris silvestris (table 1). 2.3 early aurelian faunal complexes gliozzi et al. (1997) proposed the aurelian lma (divided into early, middle and late aurelian) for late middle (from 10 to 6 mis) and late pleistocene mammal faunas (from 5 to 1 mis). the authors separated the early and middle aurelian on the basis of faunal differences between torre in pietra and vitinia fus (caloi & palombo 1990, 1996), whereas no characteristic fus have been designated for the late aurelian. the vitinia fu was considered dissimilar to the torre in pietra fu, essentially due to the abundance of a primitive fallow deer (dama dama tiberina) and the appearance of cervus elaphus, with features similar to those of modern forms of red deer and equus hydruntinus (caloi & palombo, 1996; gliozzi et al. 1997). both these fus have been defined on the basis of palaentological and stratigraphic data collected in the campagna romana area (cfr. caloi et al., 1998 and references therein). nevertheless, the structure and taxonomical composition of torre in pietra and vitinia faunal complexes are similar (palombo & mussi, 2001; palombo 2004), so the division into two fus seems to be based on weak palaeontological evidence. moreover, it is worth noting that the lfa of sedia del diavolo (rome) referred to the vitinia fu, since the abundance of dama dama “tiberina” remains were found in alluvial deposits overlaying “tufo lionato” (dated 355 ka by karner et al., 2001), where equus hydruntinus was also found (caloi & palombo, 1995). caloi et al. (1998) correlated the sedia del diavolo deposits containing dama dama “tiberina” remains with the vitinia formation (mis 7). nonetheless, on top of the deposits previously correlated with mis 7, an ash flow deposit, dated 285 ± 1 ka by karner et al. (2001), has been recognised (marra & rosa, 1995). in conformity with this new chronological data, the deposition of the fluvio-lacustrine sediments overlaying “tufo lionato” at sedia del diavolo occurred approximately between 355 and 285 ka (palombo et al., 2004). accordingly, dama dama ”tiberina” and equus hydruntinus were already present during mis 9, and thus the vitinia fu cannot be considered a valid biochron. the lfas previously ascribed to the torre in pietra and vitinia fus must be included in a single fu (named torre in pietra fu for reasons of priority). several bioevents characterised the beginning of this fu, as well as the beginning of the aurelian lma (subdivided into early and late aurelian): canis lupus and felis silvestris silvestris first appeared, as well as ursus spelaeus, substituting u. deningeri, and e. hydruntinus, megaloceros giganteus, dama dama “tiberina”, and bubalus (palombo, unpublished data), whereas ovis ammon antiqua and bison schoetensacki were not yet recorded (table 1). 3. in search of new biochronological assessments in recent years, several multivariate approaches have been developed in an attempt to supplement the similarity and association concepts. actually, multivariate analysis, if not conclusive in itself, can be a useful tool in initially defining faunal complexes and could be used to limit the biochronological framework based on classic methodologies (azanza et al., 1997, 1999; 571biochronology of the ... palombo et al., 2003 and references therein). in order to quantify the similarities and biochronological relationships among selected local mammal assemblages and establish a faunal succession, we have applied two different kinds of multivariate analysis: "appearance event ordination" (aeo; alroy, 1994) and similarity cluster analysis (see e.g. hazel, 1970). the former method uses the various relationships between the first and last appearances of taxa (actually the highest and lowest occurrences of their fossil remains in local faunas) as basic data. chronological information is inferred by detecting which taxa appear before the last occurrence of another one. the "best" solution in this procedure involving correspondence analysis is to search for a parsimonious arrangement of events that minimises the overall number of implied first and last appearance relationships. "appearance event ordination" is based on parsimony, as only relationships between first and last “appearances” in several lfas are taken into account, while occurrences of common taxa are not considered (see palombo et al., 2003, for a discussion). in the second method, the presence of common taxa provides basic data for evaluating similarities between local faunas grouped according to their taxonomic homogeneity. conversely, the absence of a species, highly dependent on taphonomic and random factors, supplies no precise information. we evaluated similarities on the basis of the jaccard binary coefficient and cluster analysis performed using the upgma method, as according to this method each member of a cluster has equal weight at all levels of clustering (cfr. hazel 1970; shi 1993; azanza et al., 1997,1999; palombo et al., 2003 and references therein) (ntsyspc program, version 2.0, rohlf, 1998). clusters do not necessarily supply chronological information or necessarily imply recognition of successive, non-overlapping, ecologically-adjusted assemblages of taxa living together in a given space and time. for this reason, the q-mode dendrogram, particularly suitable for biochronologically-oriented studies (cfr. hazel 1970), was preferred. 3.1 “appearance event ordination" calibration of the appearance event sequence (fig. 1) introduces a temporal distortion that becomes greater as available dating diminishes, as in the case of italian faunas. the distortion between the actual and estimated ages of localities indicates a contraction in time for ruscinian and early+middle villafranchian lfas (from 4.5 to 2.5 ma) and quite good correspondence for late villafranchian and galerian (2.0 to 0.400 ma), whereas early aurelian lfas are dated more recently (between 0.400 and 0 ma) (see azanza et al., 2004). after obtaining chronological relationships for italian mammal faunas, two groups can be identified, corresponding to the pliocene + early pleistocene and to the middle pleistocene lfa (fig. 1). within the first group, early villafranchian lfas appear equivalent in age, whereas the middle villafranchian are distributed in a span of less than 1 ma, in accordance with the faunal renewal characterising this faunal complex. colle pardo lfa is shown to be older than the montopoli lfa, probably due to the absence of mammuthus and equus in the former locality. the distribution of lfas ascribed to olivola and tasso fus confirms the homogeneity within each faunal complex, as well as the intermediate evolutionary stage of the poggio rosso lfa. matassino cannot be clearly positioned, given the scarcity of biochronicallyrelevant taxa. successive lfas are arranged according to the progressive renewal characterising the late early pleistocene. within the group including middle pleistocene lfas, slivia and ponte galeria lfas appear to be the most archaic among middle galerian faunas, whereas fontana ranuccio and visogliano (late galerian) undergo the greatest change, along with valdemino, which actually belongs to the middle galerian, but where some taxa (such as panthera pardus and bos primigenius) were recorded for the first time on the italian peninsula (nocchi & sala, 1997). the reduced biochronological significance of some late middle pleistocene (early aurelian) lfas makes it impossible to define their relationships. we can note that paglicci (external beds) and torrente conca lfas set a part, probably because of the occurrence of rupicapra and capra ibex (the latter only in the paglicci lfa). 3.2 similarities between lfas among large mammal faunas from the middle pliocene to the late middle pleistocene, 74 lfas were selected for a new similarity analysis, improving and updating those already performed on italian mammal lfas (palombo et al., 2003; palombo 2004; palombo & valli, in press). the faunal list for each locality was critically reviewed, including up-to-date records and personal observations. since italian fus are in some cases based on the appearance of subspecies, these taxa were also included in the data matrix. the q-mode dendrogram (fig. 2) separates local faunal assemblages (lfas) into two main groups and reveals a major separation between pliocene-early pleistocene (cluster a = villafranchian lma and early galerian, colle curti fu) and middle pleistocene lfas (cluster b = middle, late galerian slivia, isernia and fontana ranuccio fus-, and early aurelian, torre in pietra fu), the latter group having a rather higher similarity coefficient. the major separation between a and b clusters underlines the faunal reorganisation which occurred during the climatic crisis taking place at the early to middle pleistocene transition (sensu cita & castradori, 1995). this renewal phase seems to have been more important than those marking transitions from the early to the middle villafranchian (the so-called “elephantequus event” sensu lindsay et al., 1980) and from the middle to the late villafranchian (the so-called “wolf event” sensu azzaroli, 1983). a and b clusters share a low number of taxa; consequently, we can hypothesize that each one makes up part of “an ecologically adjusted group of animals with specific geographic limits and chronological range” (tedford 1970: 602). alberdi et al. (1997) have informally named these kinds of aggregates “superages”, considering them equivalent to “chronofauna” (sensu tedford 1970, emry et al., 1987). we informally name these groups “archaic faunal complex” (afc = cluster a) and “modern faunal complex” (mfc = cluster b). 572 m.r. palombo 573biochronology of the ... f ig .1 c h ro n o lo g ic a l r e la ti o n sh ip s fo r it a lia n m a m m a l f a u n a s o rd e re d a c c o rd in g t o a “ p a rs im o n yb a se d a p p ro a c h ” (a p p e a ra n c e e ve n t o rd in a ti o n , a lr o y 1 9 9 2 , 1 9 9 4 ). o rd in am e n to b io c ro n o lo g ic o d e lle f au n e lo c al i d e lla p e n is o la it al ia n a d al p lio c e n e m e d io a l p le is to c e n e m e d io o tt e n u to u til iz za n d o il m e to d o “ a p p e ar an c e e ve n t o rd in at io n ” d i a lr o y (1 9 9 2 , 1 9 9 4 ). both clusters are further divided into subclusters; within a, a1 includes early villafranchian (triversa fu) lfas as well as the ruscinian val di pugna lfa (included to indicate the age pole in the analysis, see bianucci et al. 2001), whereas a2 includes middle and late villafranchian lfas, as well as early galerian ones. accordingly, the separation between triversa and montopoli fus seems to be the most significant within the afc, emphasising the importance of the transition from early to middle villafranchian (an important turnover phase) with respect to that from the middle to late villafranchian (prevalently a dispersal phase) (palombo, 2004). within the a2 subcluster, a gap separates the a2.1 group, including middle + early late villafranchian lfas (from montopoli to tasso fus), from the a2.2 group including the latest villafranchian + early galerian lfas (from farneta to colle curti fus). actually, early late villafranchian complexes (olivola and tasso fus) were relatively static and quite homogeneous; moreover, the presence of long-persistent and frequent middle villafranchian taxa (such as mammuthus meridionalis, stephanorhinus etruscus and equus stenonis) can explain their greater resemblance to middle villafranchian lfas than to subsequent latest villafranchian ones. an extinction phase followed, during which last occurrences surpassed new ones. this phase culminated at the pirro/colle curti fu transition with a moderate turnover, due to the appearance in the course of time of some new taxa typical of the middle pleistocene (table 1). a minor gap separates the group of lfas belonging to the farneta fu from the group of pirro and colle curti fus, thus pointing out the strong similarities between latest villafranchian and early galerian italian lfas. actually, pirro nord and colle curti lfas show a relatively high similarity coefficient (jaccard index = 0.3), due to the presence of several common taxa (carnivores, rhinoceros, hippopotamus) in both localities. this fact markedly reduces the importance of the occurrence of “praemegaceros” verticornis in the colle curti lfa. within cluster b, including middle pleistocene lfas, group b1 stands apart, probably because the flas included share few taxa with other middle and late galerian lfas due to low richness (borgo nuovo, monte oliveto, pagliare di sassa) or the occurrence of peculiar taxa, such as mammuthus meridionalis in the monte tenda lea and hemibos galerianus in the ponte galeria lfa. within b2, group b2.1 includes middle and late galerian lfas. the valdemino lfa shows a low similarity coefficient and stands apart from the other lfas, probably due to the occurrence of panthera pardus, not recorded in other italian galerian lfas, and the generic identification of some taxa such as ursus sp. group b2.1 includes lfas attributed to the torre in pietra fu (e.g. la polledrara, castel di guido, malagrotta, sedia del diavolo, torre in pietra lower level, correlated with mis 9 and vitinia, casal de’ pazzi, torre in pietra upper level correlated with mis 7), although it is difficult to justify the clustering of groups of minor rank, probably because of the basic homogeneity of this faunal complex. on the basis of our results and taking into account both the biochronological significance of some rare taxa and the influence of long-lived ones, we will operationally consider clusters a and b as high rank biochrons (a = “archaic faunas complex ”afc, and b = “modern faunal complex” mfc) and the following groups as possible biochrons of lower rank: i = early villafranchian (a1); ii = middle villafranchian + late villafranchian (a2.1); iii = latest villafranchian + early galerian (a2.2); iv = middle and late galerian (b1); v = early aurelian (b2) (fig. 2). in addition, the two groups of middle (a2.1.1) and early late villafranchian (a2.1.2) should also be regarded as possible biochrons due to their low similarity coefficient. 4. remarks the transition from early to middle pleistocene faunas (from early to middle galerian mas, sensu gliozzi et al. 1997), coinciding with the onset of 100 ka climate cyclicity and vegetational changes, represents major community reorganisation in the western mediterranean area (see e.g. azanza et al., 1999, in press; palombo & valli, in press; palombo et al., in press and references therein). the importance of this renewal and ecological reorganisation is highlighted by the clear separation between clusters of “archaic” (villafranchian + early galerian, middle pliocene and early pleistocene) and “modern” (middle, late galerian + early aurelian, middle pleistocene) italian mammal faunas, as well as by the aeo. this change results from a moderate turnover, taking place at the pirro-colle curti fu transition, followed by marked faunal renewal at the beginning of the middle pleistocene. this evidence encourages reconsideration of the definition of galerian land mammal age (lma) previously proposed for italian mammalian faunas. indeed, as mentioned above, according to gliozzi et al. (1997), the appearance of “praemegaceros” verticornis, first recorded in italy in the colle curti lfa, conventionally marks the beginning of the galerian lma. however, this fauna seems more similar to villafranchian than to ensuing “true” galerian lfas, and the renewal between colle curti and slivia fus was more significant than that between pirro and colle curti fus (table 1; fig. 3). moreover, and as far as large italian mammals are concerned, analysis results confirm that during the late pliocene and pleistocene, the most important faunal renewals (due both to originations /immigrations and extinctions) are linked to major global climatic changes. faunal renewal (“elephant-equus event”, lindsay et al., 1980; azzaroli 1983; azzaroli et al., 1988) from the early to middle villafranchian faunal complexes, linked to pliocene climate worsening, is responsible for the slight similarity between a1 and a2 subclusters. this renewal may be regarded as a true turnover phase due to the high percentage of last and new appearances and the important ecological structural change in faunal complexes, involving both herbivore and carnivore guilds. moreover, this event may be considered the starting point of a dispersal phase leading to a progressive standing richness increase during the following pliocene and up to the beginning of the early pleistocene, given that new occurrences exceeded last occurrences (fig. 3). on the other hand, even if the so-called “wolf574 m.r. palombo 575biochronology of the ... fig. 2 dendogram qmode for 74 italian local faunal assemblages (q-mode) based on un-weighted data for 136 taxa. ccc = 0.92936. abbreviations: pugna= val di pugna; ponzano= ponzano di magra; gav/barb.= gaville santa barbara; p. fosciana= pieve fosciana; c.toppetti= cava toppetti; c.giacomo= costa san giacomo; v.caten= valle catenaccio c. pardo= colle pardo; t.picchio= torre picchio; mt.riccio= monte riccio; c.sgherri= casa sgherri; vald a r n o s 1 = u p p e r valdarno 1; poggio ros= poggio rosso; valdarnos2= upper valdarno 2; b. tiberino= bacino tiberino; f.acetosa= fontana acetosa; m.strada = madonna della strada; val chiana = val di chiana; pirro = pirro nord; c.curti = colle curti; mt.tenda = monte tenda; p. galeria = ponte galeria; sassa = pagliare di sassa; mtoliveto = monte oliveto; borgon. = borgonuovo; isernia = isernia la pineta; ranuccio = fontana ranuccio; notarch. = notarchirico; loreto = venosa-loreto; s.diavolo = sedia del diavolo; capriq. = capriquisisana; vitinia = vitinia, upper levels (mis 7); c.mont. = contrada monticelli; cverde = campo verde; t.pietra1 =torre in pietra , lower levels (mis 9); gr.rom. = grotta romanelli, lower levels; mt.gioie = monte delle gioie; cpazzi = casal de’ pazzi; malagr. = malagrotta; polled. = la polledrara di cecanibbio; t.pietra2 = torre in pietra, upper levels (mis 7); grlina = grotta lina; cguido = castel di guido; pfiscali = prati fiscali; grmbern. = grotta maggiore di san bernardino; pontec. = pontecorvo; t.conca = torrente conca; fsabina = fara sabina. dendogramma q-mode ricavato per 74 faune locali italiane (q-mode) sulla base dell’analisi di 136 taxa. ccc = 0.92936. abbreviazioni: pugna= val di pugna; ponzano= ponzano di magra; gav/barb.= gaville santa barbara; p. fosciana= pieve fosciana; c.toppetti= cava toppetti; c.giacomo= costa san giacomo; v.caten= valle catenaccio c.pardo= colle pardo; t.picchio= torre picchio; mt.riccio= monte riccio; c.sgherri= casa sgherri; valdarnos1=upper valdarno 1; poggioros= poggio rosso; valdarnos2= upper valdarno 2; b.tiberino= bacino tiberino; f.acetosa= fontana acetosa; m.strada = madonna della strada; val chiana = val di chiana; pirro = pirro nord; c.curti = colle curti; mt.tenda = monte tenda; p.galeria = ponte galeria; sassa = pagliare di sassa; mtoliveto = monte oliveto; borgon. = borgonuovo; isernia = isernia la pineta; ranuccio = fontana ranuccio; notarch. = notarchirico; loreto = venosa-loreto; s.diavolo = sedia del diavolo; capriq. = capri-quisisana; vitinia = vitinia, upper levels (mis 7); c.mont. = contrada monticelli; cverde = campo verde; t.pietra1 =torre in pietra , lower levels (mis 9); gr.rom. = grotta romanelli, lower levels; mt.gioie = monte delle gioie; cpazzi = casal de’ pazzi; malagr. = malagrotta; polled. = la polledrara di cecanibbio; t.pietra2 = torre in pietra, upper levels (mis 7); grlina = grotta lina; cguido = castel di guido; pfiscali = prati fiscali; grmbern. = grotta maggiore di san bernardino; pontec. = pontecorvo; t.conca = torrente conca; fsabina = fara sabina. 576 m.r. palombo fig. 3 – biochronology, standing richness and turnover changes of italian large mammal faunas from middle pliocene to late pleistocene. standing richness value was calculated according to harper’s method (harper, 1975) (nsr = nbda + nrt + 1/2 (nf + nl– no) where nsr = number of taxa that potentially occur at a given time interval, nbda = number of species present before-during and after the faunal unit, nrt = number of species present before and after but not in the faunal unit, nf = number of first appearances, nl = number of last appearances, no = number af taxa present only in the faunal unit). faunal renewal was evaluated considering all occurrences at the transition between two successive fus (turnover index, ti =% fa + % la / 2 as in torre et al., 1999). biocronologia, ricchezza standarizzata e rinnovi faunistici delle faune a grandi mammiferi della penisola italiana dal pliocene medio al pleistocene superiore. la ricchezza standardizzata è stata calcolata secondo la formula proposta da harper (1975): nsr = nbda + nrt + 1/2 (nf + nl– no); nsr = numero pesato dei taxa presenti nell’intervallo considerato, nbda = numero di specie presenti prima, durante e dopo l’intervallo considerato, nrt = numero dei taxa presenti prima e dopo, ma non durante l’intervallo di tempo considerato, nf = numero delle prime comparse, nl = numero delle ultime comparse, no = numero dei taxa presenti solo nell’intervallo considerato. l’indice di rinnovo è stato calcolato valutando il numero totale di taxa, le prime comparse e le scomparse alla transizione tra due successivi intervalli, secondo la formula ti =% fa + % la / 2 come in torre et al. (1999). event” (azzaroli 1983, azzaroli et al., 1988), seems to be a more gradual phenomenon than previously supposed, middle villafranchian lfas and early late villafranchian lfas form separate groups within a2.1, clearly separated from the group including late early pleistocene lfas, in which taxa phylogenetically related to or identical to galerian middle pleistocene ones progressively appeared, while “pliocene species” were no longer present. finally, similarity analysis results confirm the basic homogeneity of late middle pleistocene lfas. consequently, without stratigraphic constraints it is difficult to arrange these assemblages in a chronological sequence that is ascribing them to a specific mis. given these considerations, the biochronology of plio-pleistocene italian mammal faunas should be reevaluated, taking the following factors into account: “biochrons” represent time lapses during which faunas have a degree of taxonomic homogeneity; the “faunal complex” belonging to each biochron might be regarded as nonoverlapping and an "ecologically adjusted group of animals with specific geographic limits and chronological range" (tedford, 1970, pag. 602); actually, biochronology, a theoretical discipline, operationally depends on the empirical documentation of the stratigraphic ranges of fossils in superimposed sections; relative or absolute deposition dates for rock-bodies in which fossil remains are first/last documented respectively correspond only to the “ante quem” or “post quem” time of actual origination and extinction bioevents; the more detailed the bioevent sequence becomes, the more difficult it is to make correlations on a larger scale; moreover, the application of multivariate analysis may be a useful tool in defining faunal complexes having a high degree of similarity. since separation between clusters corresponds to faunal renewal, clusters themselves should have biochronological significance and should be taken into consideration for biochronological correlations. on the basis of the results obtained, the faunal complex corresponding to lfas previously ascribed to fus from farneta to colle curti should be considered as the most advanced biochron in the villafranchian lma; accordingly, the beginning of the galerian lma must correspond to the faunal reorganization occurring at the early to middle pleistocene transition. moreover, the validity and applicability of lower rank biochrons resulting from our multivariate analysis (i = early villafranchian, triversa fu; ii = middle villafranchian + late villafranchian, from montopoli to olivola + tasso fus; iii = latest villafranchian + early galerian, from farneta to colle curti fu; iv = middle and late galerian, from slivia to fontana ranuccio fu; v = early aurelian, torre in pietra fu) need further confirmation. acknowledgements the author expresses her gratitude to prof. b. sala for his comments and suggestions. the english version has been revised by dr. mary groeneweg, english language lecturer at cagliari university. work supported by miur 60% grants 2003, prof. m.r. palombo ("evoluzione degli ecosistemi continentali dell’italia peninsulare durante il plio-pleistocene: un approccio multidisciplinare"). references aguirre e. & pasini g. 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(1996) anancus arvernensis remains from the basal portion of the arctica islandica-bearing marine deposits of lower valdarno. bollettino della società geologica italiana, 115, pp. 105-113. 582 ms. ricevuto il 22 giugno 2004 testo definitivo ricevuto il 30 novembre 2004 ms. received: june 22, 2004 final text received: november 30, 2004 imp.bertoldi& first remarks on late pleistocene lacustrine deposit in the berceto area (northern apennines, italy) remo bertoldi1, alessandro chelli2, rachele roma1, claudio tellini2 & paolo vescovi2 1dipartimento di biologia evolutiva e funzionale, università degli studi di parma, parco area delle scienze, 11/a, 43100 parma. 2dipartimento di scienze della terra, università degli studi di parma, parco area delle scienze, 157/a, 43100 parma. abstract: bertoldi r. et al., first remarks on late pleistocene lacustrine deposit in the berceto area (northern apennines, italy). (it issn 0394-3356, 2004). during a geognostic survey performed by the servizio difesa del suolo of the emilia-romagna district administration in correspondence to the berceto village (northern apennines, parma province), a lacustrine sequence of about 25 metres was found in the borehole berceto spz2. this paper shows the preliminary results coming from the analysis of the berceto lacustrine deposit and suggests the morphological setting that may have contributed to the origin and development of the lake. the geological and geomorphological surveys highlight that the landslides are the prevalent processes affecting the berceto slope. the lacustrine sequence is a part of the filling of a trench that lies behind the dormant rotational rock slide involving the upper part of the slope. the entire core is 50 metres long. sedimentologic, pollen and microscopic analyses, the latters carried out on thin polished sections by both optical and scanning electron microscope (sem), together with radiocardon datings, allowed its division into 7 units and permitted us to obtain their features, ages and some inferences on their formation. from the top to the bottom of the core, a first unit (0-4.30 m) represents material reworked by the strong anthropic use of the place. below it, a level of peat (unit 2; 4.30-6.10 m), represents the ending of the lacustrine basin. it records a floristic phase characteristic of the middle-lower postglacial of the northern apennines. the unit 3 (6.10-9.20 m), together with the subsequent units 4 (9.20-17.00 m) and 5 (17.00-31.00 m), represent the real lacustrine deposit. the presence of laminated structures is the main feature of this sequence. both clastic graded millimetric laminae and couplets of dark and pale clayey ones are present. they are evident in unit 5 and begin vanishing proceeding towards the top of the sequence (unit 4), being almost completely destroyed in correspondence to unit 3. the units are affected by deformations of different types (penecontemporaneous and/or post-depositional) and extent, occurred either very close or far from the water-sediment interface. the lacustrine sequence developed during the upper pleistocene. below the lacustrine deposit, a breccia (unit 6; 31.00-48.00 m) is present. it represents a weathered cover derived from the rocks outcropping in the area, subsequently involved in mass wasting processes of the slope. it is probably related to the rotational rock slide affecting the western side of the berceto area, that may have represented the natural dam of the ancient berceto lake. the uppermost portion of the breccia contains a clayey matrix that may have waterproofed the bottom of the lake. the last unit 7 (48.00-50.00 m) may represent the substratum of the deposit and the berceto landslide. on the basis of the results of the whole study, it is possible to refer the formation of the lake starting from a geomorphologic context of the berceto slope very similar to the present one. in such a situation, the movements of the berceto landslide determined the presence of a trench, in which the lake progressively developed. the landslide movements started in the upper pleistocene and continued in the holocene up to the development of the present hollow of berceto. riassunto: bertoldi r. et al., note preliminari sul deposito lacustre tardo pleistocenico di berceto (provincia di parma). it issn 0394-3356, 2004). un sondaggio (berceto spz2) eseguito dal servizio di difesa del suolo della regione emilia romagna nel corso di una campagna geognostica condotta in corrispondenza del paese di berceto, posto alla sommità di un versante a cavallo tra le valli dei torrenti baganza e manubiola nel settore parmense dell’appennino settentrionale, ha individuato una sequenza lacustre dello spessore di circa 25 metri. lo scopo di questa nota è di illustrare i risultati preliminari derivanti dall’analisi del deposito lacustre di berceto e di ipotizzare, anche sulla base degli elementi morfologici dell’area, lo scenario che potrebbe aver portato alla formazione del lago. la sequenza rinvenuta costituisce parte del riempimento di quella cha si presenta come una blanda depressione, orientata circa nnessw, occupata dal paese di berceto. la depressione è l’espressione morfologica di una trincea determinatasi nell’evoluzione della frana rotazionale quiescente in roccia che interessa la porzione altimetricamente più elevata del versante che da berceto degrada, verso nw, fino al corso del torrente manubiola. gli elementi morfologici rilevati hanno permesso di determinare come l’intera area sia interessata, prevalentemente, da morfogenesi gravitativa, che si esprime attraverso la presenza di numerose frane quiescenti di tipo complesso, condizionate dai caratteri litologici e strutturali delle rocce affioranti. la carota recuperata nel sondaggio berceto spz2 misura una lunghezza totale di 50 metri. su di essa è stata condotta una dettagliata analisi, implementata da osservazioni sia al microscopio ottico sia al sem di sezioni sottili tagliate nelle parti della sequenza lacustre che hanno conservato le strutture più significative per l’interpretazione della genesi del deposito. unitamente a ciò è stata condotta un’analisi palinologica preliminare del deposito e sono state effettuate una serie di datazioni radiocarbonio su materiale organico prelevato a differenti livelli entro la carota stessa. complessivamente gli studi condotti hanno permesso di suddividere l’intera carota in 7 unità. dall’alto verso il basso è stata individuata una prima unità (0-4,30 m) costituita da una breccia siltoso-argillosa polimittica che è il risultato del rimaneggiamento dovuto all’attività antropica. a questa fà seguito l’unità 2 (4,30-6,10 m), uno strato di torba alla cui base è presente un sottile livello di sabbie ricco di resti vegetali. questa unità presenta un contenuto floristico tipico del postglaciale medio-inferiore dell’appennino settentrionale, mentre non è rappresentata la storia paleobotanica dell’inizio dell’olocene e quella dell’olocene medio-superiore. questa mancanza è forse giustificata dall’evidente rimaneggiamento dell’intero livello; infatti la torba si presenta in un cattivo stato di conservazione, con chiare indicazioni di ossidazione e frantumazione. con il sottostante intervallo costituito dall’unità 3 (6,10-9,20 m) compare la sequenza di chiara origine lacustre. si tratta di un deposito massivo generalmente siltoso e localmente costituito da sabbie molto fini di colore grigio chiaro, con intraclasti di colore da grigio palliil quaternario italian journal of quaternary sciences 17(2/1), 2004, 133-143 134 r. bertoldi et al. 1. introduction during a geognostic survey performed in correspondence to the berceto village (northern apennines, parma province) by the servizio difesa del suolo of the emilia-romagna district administration, a lacustrine sequence of about 25 metres was found in the borehole berceto spz2. it is part of the filling of an hollow placed in the higher part of the slope where the village lies. the discovery of this lacustrine sequence represents a rare and very interesting finding within this part of the emilia apennines, particularly for its location. indeed lacustrine deposits from different sites in the high part of the emilia apennines, were sampled and studied in detail, but they were, mainly, lacustrine and/or peat sequences deposited behind glacial deposits and landforms, i.e.: lateral and frontal moraine ridges (watson, 1996). detailed studies on pollen sequences and radiocarbon datings allowed the identification of the main characteristics of pollen records from across the area and to examine the chronology of similar changes in pollen stratigraphy, from the holocene to the late glacial, up to 12,000 yr b.p. (bertoldi, 1980; bertoldi et al., 1986; cruise, 1990; lowe & watson, 1993; montanari et al., 1994; watson, 1996). unlike these latter, the berceto deposit is in the middle portion of the apennines area, where aggressive geomorphological processes, due to gravity and running waters, acted during the holocene, prejudicing against the preservation of relict landforms and deposits. the paper shows the preliminary results coming from the analysis of the berceto lacustrine deposit and suggests the morphological setting that may have contributed to the origin and development of the lake. 2. geological setting 2.1 general framework the berceto area is situated a few kilometres north of the cisa pass (fig. 1) and is therefore close to an important transversal tectonic discontinuity (i.e. the taro system auctt.) separating the northwestern ligurian-emilian apennines segment from the southwestern tuscan-emilian segment (bernini et al., 1997). these two apennine sectors mainly differ in the degree of tectonic uplift that involved them. while the nw sector is almost completely overthrust by external ligurian sequences (marroni et al., 2002), the se secdo a grigio scuro. la sottostante unità 4 (9,20-17,00 m) è rappresentata da un deposito siltoso, di colore grigio-giallastro, con struttura caotica. si rinvengono livelletti costituiti da lamine chiare e scure spesso di aspetto evanescente, deformate in modo duttile e, localmente, sabbie fini contenenti resti vegetali. l’analisi dei pollini contenuti nelle due unità 3 e 4 ha permesso di ricostruire una sequenza di eventi con un certo grado di coerenza, attribuibili verosimilmente al tardiglaciale. il contenuto della porzione medio-inferiore del sub-intervallo palinologico definito dalle unità 3 e 4 rimanda ad un periodo con caratteristiche cilimatiche glaciali di tipo stadiale cui segue, nella parte alta, un periodo di tipo interstadiale. datazioni radiocarbonio effettuate su campioni prelevati a 6,20 e 11,65 metri, hanno restituito valori rispettivamente di 11.150±70 14c yr b.p. e 14.480±50 14c yr b.p. e collocano le unità in periodi con condizioni climatiche come quelle prospettate dall’analisi palinologica, in accordo con le suddivisioni climatostratigrafiche per il pleistocene superiore, proposte da ravazzi (2003). i caratteri delle unità 3 e 4 suggeriscono, per la loro deposizione, un contesto di ambiente lacustre caratterizzato da una certa dinamicità. in particolare è verosimile ritenere che la deposizione risenta degli effetti di fenomeni gravitativi che hanno coinvolto direttamente i depositi laminati deformandoli e della rimozione, dalle porzioni marginali verso il centro del lago, di materiale che viene risedimentato, in occasione di afflussi importanti dal bacino di alimentazione. la deformazione penecontemporanea dei depositi risulta più evidente nell’unità 3 rispetto all’unità 4. l’unità 5 (17,00-31,00 m) è composta da lamine gradate siltose clastiche con spessori di qualche millimetro, di colore da giallastro a grigio chiaro, e lamine argillose submillimetriche di colore grigio scuro contenenti sostanza organica, cui si associano, talvolta, lamine sottilissime biancastre. le lamine sono sempre ripiegate e interessate da superfici di taglio, con andamento da suborizzontale a ondulato, tali deformazioni risultano post-deposizionali e non si sono verosimilmente sviluppate all’interfaccia acqua-sedimento. le lamine argillose scure si presentano come bande millimetriche di colore bruno composte di argilla, in cui compare, in maniera diffusa, materiale siltoso. l’analisi palinologica preliminare, sebbene condotta su di un numero esiguo di spettri, e la data radiocarbonio di 29.620±290 14c yr b.p., restituita da un campione prelevato a 22,50 metri, hanno permesso di collocare la sedimentazione dell’unità 5 nel würm medio delle alpi (ravazzi, 2003). infatti in concomitanza con la glaciazione würmiana alpina, si verificò anche nell’appennino settentrionale un massimo di espansione dei ghiacciai, ben espresso nelle valli dei torrenti parma e cedra. nella limitrofa val baganza, con ogni probabilità, si instaurarono, invece, condizioni prevalentemente di tipo periglaciale. nell’unità 5 le lamine chiaro-scure sono l’espressione di fasi di deposizione in un ambiente lacustre tranquillo, determinato da una ridottissima dinamicità delle acque del lago. a queste si associano le lamine clastiche la cui deposizione è avvenuta o in occasione dei periodi di apertura del sistema lago agli influssi esterni, o in conseguenza di fenomeni di risedimentazione per scuotimento del fondo del lago in occasione dei movimenti della frana. le pieghe e le superfici di taglio che interessano l’unità 5, testimoniano il coinvolgimento dei depositi in deformazioni legate verosimilmente a fasi di movimento della frana in roccia di berceto. la successiva unità 6 (31,00-48,00 m) è costituita da una breccia a clasti centimetrici angolosi immersi in una matrice siltosa. nella parte sommitale dell’unità la matrice della breccia diviene via via più argillosa e potrebbe aver avuto il ruolo di materiale impermeabilizzante il fondo del lago, contribuendo all’impostazione di quest’ultimo. il deposito, fortemente ossidato, dovrebbe rappresentare una coltre derivante dall’alterazione dell’originario substrato costituito da arenarie di scabiazza (cfr. arenarie di ostia), largamente affioranti nell’area, successivamente coinvolta in fenomeni gravitativi da mettere, verosimilmente, in relazione con la frana in roccia che interessa la parte sommitale del versante di berceto. negli ultimi due metri il sondaggio (unità 7; 48,00-50,00 m) si è approfondito all’interno delle argille a palombini di monte rizzone, che dovrebbero rappresentare il substrato dell’intero deposito e del movimento franoso, e che in affioramento compaiono a sw dell’abitato di berceto. sulla base di quanto emerso dallo studio geomorfologico del versante e dall’analisi della carota berceto spz2 si può prospettare che il lago si sia formato a partire da una situazione morfologica del versante di berceto non molto diversa da quella attuale. in un tale contesto il progressivo collasso della frana in roccia avrebbe portato all’apertura della trincea nella quale si sarebbe impostato il lago. tale scenario prevede l’inizio dell’evoluzione della frana a partire almeno dal pleistocene superiore e la sua prosecuzione fino all’olocene e in quest’epoca la depressione si sarebbe progressivamente colmata fino a raggiungere l’attuale conformazione keywords: late quaternary landslide, laminated lacustrine deposit, baganza valley, northern apennines. parole chiave: frana tardo-quaternaria, deposito lacustre laminato, val baganza, appennino settentrionale. 135first remarks on late pleistocene ... fig. 1 geological map of the berceto area (for the cross-section bb’ see fig. 3). 136 tor is more exhumated and amply exposes the underlying subligurian units and the deeper foredeep units characterised by a ne-verging thrusting. the tectonic uplift of the tuscan-emilian segment, clearly visible in the structural feature of the macigno outcropping along the main apennine backbone, was formed in the pleistocene (argnani et al., 2003). the uplift of the backbone is accompanied by an extensional tectonic regime developing nw-se fault systems responsible for the grabens on the tyrrhenian side of the apennines (bernini & papani, 2002). corresponding to the cisa pass transversal lineament, the outcroppings of the tuscan and umbrian units are interrupted towards nw by a general nw axial plunging of the folding (bernini & vescovi, 2002) and by transtensive sw-ne faults, with sinistral strikeslip components (vescovi, 1988). 2.2 tectonic evolution of the berceto area the area of the village of berceto, close to the divide between the torrents manubiola and baganza, is obliquely crossed by a high-angle fault with left-handed transpressive kinematics, and a sw-ne direction binds a tectonically uplifted area to the nw (fig. 1). near berceto, it is thus possible to identify an sverging recumbent anticline, affecting the scabiazza sandstone, cut by a sub-horizontal thrust surface which formed during the ne-verging neogene thrusting. the recumbent anticline involving the scabiazza sandstone is indicated in the geological structural map in fig. 1 illustrating its axial trace separating the normal limb of the sardello-case san genesio area from the overturned limb on which the northern outskirts of the town of berceto are situated. the stratigraphically lowest lithofacies in the unit, rich in sandstone layers, outcrops in correspondence with the normal limb, while the outcrops of the overturned limb, where the northwestern part of the village sits, are characterized by the overlying marly lithofacies. in the rest of the town, the formation is only visible in excavations and appears to belong to a normal limb uplifted by faulting. here the scabiazza sandstone, which is heavily fractured, presents limited thicknesses and stratigraphically follows the palombini shale of mt. rizzone (vescovi, 2002), which is well exposed in an excavation located slightly sw of the seminario (fig. 2) and also found in the borehole drilled in the village (fig. 1). it is therefore clear that the main portion of the village is located on a tectonically greatly uplifted normal limb and thus heavily eroded, phenomenon which obviously also involves the underlying mt. caio flysch. this uplifting developed ne-trending transtensive faulting and ssw-nne normal faults, characterized by low magnitude of offset; also present are nw-se trending normal faults, which are likely to fall within the framework of the extensional tectonic regime which is well developed in the apennine inner sector. this tectonic framework provides a boundary for an area where low thicknesses of scabiazza sandstone overly substantially shaly units (i.e.: palombini shales of mt. rizzone and shales of the ophiolitic complex). these features predisposed the gravitative movements towards nw, probably accompanied by downslope rotational slides during the quaternary morphogenesis evolution of the berceto area. 3. geomorphological setting the berceto village lies at 830 m a.s.l., in correspondence to the divide between the baganza and manubiola torrents, this latter being a tributary of the taro river, and is located in the middle apennines not far from the main glaciated terrains during the upper pleistocene (federici & tellini, 1983; gngfg, 1988). the berceto slope, which runs westwards, extends between the village itself and the manubiola fig. 2 se-dipping palombini shale of mt. rizzone formation. it was exposed some years ago in an excavation located near the seminario (see fig. 1). this rock, in which the slip surface of the dormant rotational rock slide of berceto developed, was found at the bottom of the berceto spz2. r. bertoldi et al. 137 fig. 3 sketch map of the main geomorphological features of the berceto area. legend of the cross-section bb’: 1) sliding surface of landslide, 2) landslide body; for the geologic symbols used in it see the legend of fig. 1. first remarks on late pleistocene ... 138 torrent, (represented in the tectonic sketch map of fig. 1). the geomorphologic survey highlights that the landslides are the prevalent processes on it. the most landslides, apart from some small active ones, are dormant and of complex type (fig. 3). they are rotational and/or roto-translational slides, with relatively deep surface of movement, and earth-flows, especially in the sw part of the slope. in the detachment area, corresponding to the divide between manubiola and baganza torrents, dormant rotational rockslides involving scabiazza sandstone and palombini shale of mt rizzone formations prevail (fig. 3). on these landslides lie the ancient portion and most of the new portion of berceto village. a mild hollow, with a long axis oriented approx. nne-ssw and with an extension of about 30x103 m2, takes up the area between the village and the divide eastwards. it represents the morphological expression of the trench behind the rotational slide. the borehole berceto spz2 was drilled in its centre (fig. 3) and a core of about 50 metres was extracted. on the right side of the manubiola valley, the lower portion of the slope presents very slow movements. in the last years they have been monitored by gps measurements carried out by the society of the cisa motorway. recently even researchers of the department of earth sciences of modena and reggio emilia university have monitored them by sar interferometry. these movements may be the result of a deep seated gravitational slope deformation (dsgsd) (ronchetti, 2002-2003) that involves part of the slope (fig. 3). some geomorphologic elements, i.e. deep torrential cuts, small trenches pulled apart from scarps and small landslides placed in correspondence with the edges of the breakdown area, are the morphological expression of the existence of this large landslide (fig. 3). 4. the core berceto spz2 4.1 description and analysis of the berceto spz2 core a detailed macroscopic analysis of the core was performed. it allowed the recognition of seven lithologic units (fig. 4). two metres of palombini shale of mt rizzone (bedrock) were found at the bottom of the borehole. a preliminary petrographic and mineralogical study of unit 5 was carried out on thin polished sections by both optical and scanning electron microscope (sem). mineral analyses were made using an electron microprobe jeol-6400 equipped with an energydispersive microanalytic system; operating conditions were an accelerating voltage of 15 kv and a probe current of 0 na. they were cut in correspondence with levels where the structures are very evident. the detailed description of the lithologic units is shown in fig. 4. unit 5 shows well-preserved laminae. some details of these sedimentary structures are presented in fig. 5. in fig. 5a a sequence of clastic and dark organic laminae is shown. the clastic laminae show a quartz rich basal portion and a gradation from coarse to fine, sometimes well visible as in (fig. 5a (1)). substantially, they appear as thin turbidites and are like graded beds (sturm, 1979). in the clastic laminae the sem analyses highlighted the presence of quartz, albite, na-ca plagioclase, calcite, dolomite, hornblende, biotite, chlorite, muscovite, sphene, fe-ti oxides. the matrix of the laminae is formed mainly by mixed layers of clay minerals (illite/smectite). the minerals present in the clastic laminae reflect the composition of the rocks outcropping in the area. in the middle part of the photograph two vanishing and discontinuous dark levels are among three clastic laminae. they represent the relicts of the clayey laminae eroded by the thin turbidites (fig. 5a (2)). the analyses of the clayey laminae show they are mainly formed by mixed layers of clay minerals (illite/smectite), with rare grains of quartz, calcite, chlorite, illite, dolomite, ilmenite and muscovite. the grains with elongated shape are arranged parallel to the layers itself. the same features are visible in fig. 5b too. the basal erosional boundary of a turbiditic layer (fig. 5b (1)) is worth noting. it is highlighted by the alignment of small vanishing bodies of dark clay and by the overlaying quartz rich portion of a turbidite lamina. in the upper part of the photograph there are two turbidite layers (fig. 5b (2)) that show very deformed basal boundaries. these features are well reproduced in fig. 5c that represents the prosecution towards right of the same laminae of the previous photograph. in fig. 5c (1) load casts are shown. they are common in the loaded surfaces and they arise from the sinking of silt into dark clay, leading to the upward injection of little clayey flame structures. in fig. 5c (2) the dark clayey lamina deformed by the overlaying clastic bed is evident. the deformation occurred during the turbidite sedimentation of the clastic lamina, which had a current flow from the right to the left of the photograph. where the turbidite sedimentation did not cause the deformation of the underlying clay lamina, the detailed features of the latter are visible. fig. 5d represents the close-up of the middle part of fig. 5b. the presence of couplets of dark and pale laminae (fig. 5d (1)) is clear in it. some of the pale laminae were also analysed, dolomite and mixed layers clay minerals (illite/smectite) were found. fig. 5e shows detail of deformed laminae in unit 5 (fig. 4). they are affected by folding and shear surfaces. the photograph shows the very ductile character of the deformation, connected to the plastic state of this deposit. 4.2 pollen analysis and radiocarbon datings the pollen analysis of the berceto spz2 core in the interval of depth 0-31 metres was performed. the core was sampled closely and a hundred samples were taken. up to now twenty samples were examined for the general recognition of the pollen contents of the sequence. they were chosen to represent the whole interval and prepared by employing the classic methodological approach of pollen enrichment. the procedures include washing with hcl, soaking in hf, luber technique, boiling in diluite koh followed by enrichment procedures, in particular gravitative separation r. bertoldi et al. 139 fig. 4 sedimentologic c h a r a c t e r i stics of seven units making up the berceto spz2 core and their meaning (on the right hand), r a d i o c a r b o n d a t i n g s performed on organic matter (in the middle) and characteristic features of the l a c u s t r i n e deposit (on the left hand) are presented. first remarks on late pleistocene ... using heavy fluids (zncl2 at d = 2,004) and finally sonication. on the basis of the preliminary results of the pollen analysis it was possible to delineate the first sketch of the floristic and vegetational evolution of the area and to divide the interval 0-31 metres into four palynological subintervals, only partly in agreement with the sedimentologic units. the first subinterval ranges between 0.00 and 4.40 metres. the microscopic analysis of two levels containing vegetal scraps proves the scarcity and bad state of preservation of the sporomorphs. this evidence confirms the reworking of this unit, already recognized from the sedimentological point of view. the second subinterval corresponds to unit 2 (fig. 4) and ranges between 4.40 and 6.10 metres. six levels, spaced 50 cm from each other, were considered altogether. the arboreal plants (ap) prevail over the non-arboreal plants (nap), the latter being only 20% of the pollen sum. within the ap abies clearly prevails, being represented by more than 40% of the total amount. quercus, sometimes accompanied by rather low values of tilia and ulmus, shows lower percentages than 20%, except for the spectrum where the oaks are dominant on the silver fir. pinus shows continuously decreasing percentages (from 20% to 8%) from the bottom to the top of the subinterval, whereas betula, corylus, alnus, populus and salix show very low values. fagus is present only in the uppermost spectrum. the sporomorphs appear to be badly preserved in every level, especially those of abies. they are dark brown, corroded, degraded and crumpled. the microscopic examination reveals that the remains of peat are represented by amorphous dark brown organic matter, almost completely oxidized. nevertheless, frequent remains of vessels of broad-leaved trees, scarce findings of fibre-tracheids of conifers and rare cellular aggregates of epidermis-type are present. the third subinterval ranges from 6.10 to 17.00 metres, enclosing sedimentologic units 3 and 4 (fig. 4). twelve samples regularly distributed along this part of the core were examined. in every spectrum the ap prevails, with pinus clearly dominant. the herbaceous flora (nap) is qualitatively and quantitatively rich. the main types such as artemisia, chenopodiaceae, gramineae, compositae, helianthemum, caryophyllaceae, etc., are always present and show positive and negative fluctuations. a significative difference is recognizable between the spectra corresponding to the uppermost metre of the subinterval and those of the part below. in the former comparatively plentiful pollen grains of betula, abies, quercus and corylus are present together with pinus. in the latter the arboreal flora is qualitatively poorer: only scarce findings of betula and picea are present, together with pinus. ephedra and juniperus are almost always present. the fourth subinterval, from 17.00 to 31.00, corresponds to sedimentologic unit 5 of fig. 4. up to now only four out of about fifty spectra have been analysed, nevertheless some remarks can be made. the pollen flora (ap + nap) seems qualitatively and quantitatively poorer compared to the previous subinterval. pinus becomes predominant and few other types of pollen from pioneer plants (ephedra, juniperus, hippophae) are represented. rare grains of betula and picea are present. organic matter was extracted from different levels of the core and then submitted to beta analytic inc. (miami, florida, u.s.a.) in order to perform radiocarbon datings. at the level of very fine sand, just below the boundary between units 2/3, a sample containing scraps of plants was extracted at 6.20 metres. it supplies a date of 11,150±70 14c yr b.p. corresponding to 13,390140 fig. 5 the microscopic photographs show the features and characters of the laminated deposits of the unit 5. they are the best preserved of the entire lacustrine sequence. r. bertoldi et al. 13,240/13,220-12,900 cal 14c yr b.p. (beta 178882). in unit 4 a sample was extracted at 11.65 metres. it contained scraps of plants and small wood fragments. it provides a date of 14,480±50 14c yr b.p., 17,70517,000 cal 14c yr b.p.(beta 181866). finally organic matter was extracted at 22.50 metres from a dark lamina in unit 5. it supplies a date of 29,620±290 14c yr b.p. (beta 181867). although the results of the pollen analyses are still preliminary in type, they show a sequence of floristicvegetational events, which permits the possibility of reconstructing the climatic evolution of the area, corresponding to an interval of the upper pleistoceneholocene period, even if with some gaps, especially in the upper part. indeed the first subinterval (corresponding to unit 1 of fig. 5) suffered a hard reworking which did not give any meaningful result from pollen analyses and the second one (corresponding to unit 2 of fig. 5) presents wide gaps. the latter records a floristic phase characteristic of the middle-lower postglacial vegetational development of the northern apennines (bertoldi, 1980; lowe & watson, 1993), as proved by the well-known prevalence of abies and the almost complete lack of fagus. furthermore, they seem to lack the onsets of the holocene and undoubtedly of the middle-upper holocene paleobotanical history. on the other hand, the bad state of preservation of the sporomorphs together with the remains of peat clearly oxidized and broken up mean that the peat level likely underwent one or more events of reworking. the results obtained from the pollen analysis of the third subinterval appear to be more organized. wellpreserved pollen grains permitted the reconstruction of a sequence of events. the pollens of the flora and vegetation of the higher part of the subinterval are characteristic of interstadial periods, likely of the lateglacial interstadials, whereas those of the lower part of stadial ones. this evidence is supported by the radiocarbon datings performed on the samples at 6.20 and 11.65 metres. indeed, the dating of the first sample is referable to the late glacial interstadial of the climatostratigraphic subdivisions proposed by ravazzi (2003), deriving from the improvement of the chronostratigraphy of the late glacial from orombelli & ravazzi (1996). the dating of the second sample refers to the “early late glacial” (ravazzi, 2003), corresponding to the oldest dryas, in which more than one glacial stadial are reported for the different sectors of the alps (maisch, 2000). at present, few remarks can be made on the fourth subinterval. the small number of the pollen spectra analysed does not permit us to characterize it completely from the floristic and vegetational point of view. nevertheless, the analyses performed highlighted a paleo-environment of glacial type, as the radiocarbon dating at 22.50 metres confirms. indeed, it is included in the middle-pleniglacial stadial-interstadial phase of the alps (ravazzi, 2003) when also in the northern apennines the glaciation took place, e.g. in the close parma valley the glaciers had the great development (federici & tellini, 1983). 4.3 remarks on the sequence of the core the borehole reached the palombini shale of mt rizzone outcropping close to berceto (fig. 1). it goes down two metres in this formation which represents the bedrock (fig. 4). above the bedrock, there is a breccia (unit 6 in fig. 4) that in our opinion represents a weathered cover derived from the scabiazza sandstone, and subsequently involved in mass wasting processes of the slope. this deposit is probably related to the rock block slides involving the western side of the berceto area (figg. 1 and 3), which may have represented the natural dam of the ancient berceto lake. the uppermost clayey breccia may have waterproofed the bottom of the lake. above the breccia, the lacustrine laminated sequence (unit 5 in fig. 4) begins. most of the laminae show clastic graded texture and represent small repeated turbidite events. they may record either the sediment influx from the catchment to the lake or the flows from the marginal parts of the bottom of the lake. the dark and pale laminae are probably produced by precipitation and flocculation of clay-rich material, during periods characterized by the lack of coarse clastic inputs. the above unit 4 (fig. 4) does not show a regular laminated structure but vanishing dark and pale laminae are still visible. these features testify to the existence of the previous sedimentary structure of the material in the same way as in unit 5. in the following unit 3 (fig. 4) the deformation is more pronounced, the original laminated structure is almost destroyed and the material is rather homogeneous. on the whole, the sequence of units 5, 4 and 3 shows an increased deformation from the bottom to the top. this may be related to a unique important dynamic event or a sequence of different ones. in any case, the deformation was registered by these units in different ways. the deepest unit 5 records the deformation forming folds and shear surfaces, whereas in the upper units (4 and 3), closer to the water-sediment interface, the laminae were almost completely destroyed. the overlaying unit 2 (fig. 4) represents the ending of the lacustrine basin, passing from a thin sandy level to peat. finally, unit 1 (fig. 4) records no stratigraphic features, because of its complete reworking. this situation was determined by the strong anthropic use of the place, especially in the 20th century. 5. final remarks the geological and geomorphologic surveys of the berceto area highlighted the presence of a dormant rotational rock slide involving the area of the village, responsible for the trench at the top of the slope. the analyses (sedimentologic, pollen and microscopic analyses) performed on the berceto spz2 core allow us to put forward some remarks on the meaning of the different parts of the deposit filling the trench. in our opinion, the peat (unit 2 in fig. 4) represents the last deposit filling the hollow. despite the bad state of preservation both of the peat and of the above unit 1, the pollen analysis of the former allows us to refer its starting at least to the lower-middle holocene (boreal-atlantic?). 141first remarks on late pleistocene ... the units 3, 4 and 5 (fig. 4) represent the real lacustrine deposit. the radiocarbon dating and pollen analyses of unit 3 reveal that it deposited during the lateglacial, probably during an interstadial period. in this latter, the lack of well-defined laminae, the massive appearance of the deposit and the presence of intraclasts suggest that the deposition was in a dynamic environment. the sedimentation may be linked either to the occurrence of landslides and/or mass wasting, directly involving laminated lacustrine deposits, or to the re-sedimentation of fine material in the central part of the lake. this latter occurrence could be linked to the re-mobilization of laminated deposits from the marginal parts of the lake, because of the impact from the renewed coarse sediment influx from the catchment to the lake. the great similarity of the sedimentologic features between units 3 and 4 may lead to the assumption that they were involved in the same processes. nevertheless, the possibility to recognize, in unit 4, even vanishing dark and pale laminae suggests a lower extent of the deformation. indeed in our opinion, in unit 4 both penecontemporaneous and post-depositional deformations are present. this latter occurred when the sediment was more coherent and far from the watersediment boundary. unit 5 represents the most interesting part of the lacustrine deposit. the small post-depositional folds and the shear surfaces, affecting the laminae, testify to the fact that the deposit was involved in both compressive and, likely, extensive deformations. in our opinion, these deformations may have occurred during the different phases of movement of the landslides of the berceto slope. the sedimentologic features, together with the radiocarbon dating (29,620±290 14c yr b.p.) and the pollen analyses, suggest that the deposition was concomitant with climatic conditions of a glacial type, when in the area studied, periglacial ones were likely established. the dark and pale laminae could be the result of quiet sedimentation, perhaps decantation, linked to a dynamic of the water reduced to the minimum. the situation responsible for the formation of clastic laminae presents itself again. they either represent events of sedimentation of very fine clastic material that formed when the lake-system opened, and the sediment influx from the catchment occurred, or re-sedimentation in the occurrence of landslides activity, when the movement caused the re-mobilization of the unconsolidated sediment of the bottom of the lake. the knowledge we currently have about the laminated lacustrine deposit does not allow us to put forward definite data concerning its meanings as regards the biological and geochemical response to factors leading to their formation. nevertheless, the evidence on the laminae allows us to make some remarks. the nature of the laminae, their composition and the relationships between them prove that they are clastic laminations (o’sullivan, 1983). the couplets of dark and pale laminae are structured like varve, but it is early to advance any inference about their real meaning as annual or seasonal layered deposits. this is clear if one considers that the formation of clastic varves is very sensitive to the sediment influx and mechanisms of transport within the lake. particularly it is regulated by the flush of the first peak discharge of the season, whose behaviour does not assure that couplets of laminae represent true varves but rather longer and shorter time intervals (anderson & dean, 1988). in addition, the possibility of re-sedimentation of sediment complicates the state further. in any case, even if the laminae could be considered varves they pertain to the non-glacial ones. unit 6 is the deepest recognized within the berceto spz2 core. as reported above, it is a breccia containing very weathered material from a fine facies of the scabiazza sandstone and it could represent either the filling of the berceto landslide trench or an older eluvial cover. the upper part of the unit becomes rich in very fine matrix that allowed its waterproofing and the birth of the lake. on the basis of this evidence and their meaning, we advance the hypothesis that the formation of the lake started from a geomorphologic context of the berceto slope very similar to, although obviously not exactly the same as, the present one. in such a situation, the pleistocene movements of the berceto landslide determined the presence of a trench, in which the lake progressively developed. the landslide movements continued up to the holocene and they drove to the development of the present hollow of berceto. essentially, the berceto lake may be related to the dynamic of this landslide. this latter started in correspondence of the middle period of the last glaciation of the northern apennines and continued to develop through the late glacial. analogous ancient landslide was already reported in the middle parma valley (carobbio landslide; 25,129±160 14c yr b.p., 17,330±110 14c yr b.p., tellini & chelli, 2003). the study of berceto spz2 core is still in progress especially for the part concerning the real lacustrine deposit (units 3, 4 and 5 in fig. 4). in our opinion, the detailed study of the sequence may provide useful proxy data to investigate the palaeoclimatic conditions of this part of the northern apennines. this information could also be important in the definition of the climatic factors, such as periods of increased rainfall, forcing the phases of activity of the berceto slope landslides, contributing to the study carried out on this topic in the last few years for the emilian apennines (bertolini & tellini, 2001; tellini & chelli, 2002; 2003). acknowledgements this study was supported with the grant of the research project “late quaternary climate change and slope instability in the northern apennines (italy)” (chief: prof. c. tellini, university of parma; national chief: prof. m. soldati, university of modena and reggio emilia), and the grant of the local research project fil 2004 “evoluzione geomorfologica tardoquaternaria: casi di studio nelle alpi marittime e nell’appennino settentrionale” (chief: dr. s. perego, university of parma). we are grateful to dr. a. montanini (department. of earth sciences, university of parma) for the optical and sem analyses of the thin sections and the useful suggestions upon the mineralogical compositions. many thanks to e. masini for drawing of figs 1 and 3. this paper is the synthesis of the work and reflections of all the authors, but each worked on a specific 142 r. bertoldi et al. part of the paper. p. vescovi took care of the geological setting of the area, while a. chelli and c. tellini dealt with the geomorphologic setting and the landslides of the berceto area. the description, analysis and interpretation of the berceto spz2 core is the result of the work performed by a. chelli, c. tellini and p. vescovi together. r. bertoldi and r. roma dealt with the pollen analyses and their paleoclimatic interpretation. the opinions of all the authors are synthesized in the final remarks. references anderson r.y. & dean w.e. 1988 lacustrine varve formation through time. palaeogeog. palaeoclim. palaeoecol., 62, 215-235. argnani a., barbacini g., bernini m., camurri f., ghielmi m., papani g., rizzini f., rogledi s. & torelli l. 2003 gravity tectonics driven by quaternary uplift in the northern apennines: insights from the la spezia reggio emilia geo-transect. quat. int., 101-102, 13-26. bernini m. & papani g. 2002 la distensione della fossa tettonica della lunigiana nord-occidentale (con carta geologica alla scala 1: 50.000). boll. soc. geol. it., 121, 313-341. bernini m. & vescovi p. 2002 carta strutturale della media val taro alla scala 1: 100.000. atti del terzo seminario sulla cartografia geologica, bologna 26-27 febbraio 2002, 58-63. bernini m., vescovi p. & zanzucchi g. 1997 schema strutturale dell'appennino nord-occidentale. acta naturalia de “l'ateneo parmense”, 33, 43-54. bertoldi r. 1980 le vicende vegetazionali e climatiche nella sequenza paleobotanica würmina e postwürmiana di lagdei (appennino settentrionale). acta naturalia de “l'ateneo parmense”, 18, 147175. bertoldi r., timossi a.m., borghi m.l. & magri d. 1986 studio di una piccola torbiera montana dell’appennino emiliano attraverso i microfossili vegetali. l’italia forestale e montana, 41 (4), 216230. bertolini g. & tellini c. 2001 new radiocarbon dating for landslide occurrences in the emilia apennines (northern italy). trans. japan. geom. un., 22 (4), c-23. cruise g.m. 1990 holocene peat initiation in the ligurian apennines, northern italy. rev. paleob. palyn., 63, 173-182. federici p.r. & tellini c. 1983 la geomorfologia dell’alta val parma (appennino settentrionale). riv. geogr. it., 90, 393-428. gruppo nazionale geografia fisica e geomorfologia (gngfg) – cnr 1988 il paesaggio fisico dell’alto appennino emiliano. studio geomorfologico per l’individuazione di un’area da istituire a parco. a. carton & m. panizza (eds.), grafis edizioni, 182pp. lowe j.j. & watson c. 1993 – lateglacial and early holocene pollen stratigraphy of the northern apennines, italy. quat. sc. rev., 12, 727-738. marroni m., molli g., montanini a., ottria g., pandolfi l. & tribuzio r. 2002 the external ligurian units (northern apennine, italy): from rifting to convergence of a fossil ocean-continent transition zone. ofioliti, 27 (2), 119-131. maisch m. 2000 the longterm signal of climate change in the swiss alps: glacier retreat since the end of the little ice age and future ice decay scenarios. geogr. fis. dinam. quat., 23, 139-151. montanari c., guido m.a., boccaccio a. & rametta m. 1994 paleoecologia olocenica del monte gottero (parma) nel quadro della storia del popolamento vegetale dell’appennino ligure. il quaternario – italian journal of quaternary sciences, 7 (1), 373380. orombelli g. & ravazzi c. 1996 the late glacial and early holocene: chronology and paleoclimate. il quaternario – italian journal of quaternary sciences, 9 (2), 439-444. o’sullivan p.e. 1983 annually-laminated lake sediments and the study of quaternary environmental changes – a review. quat. sc. rev., 1, 245-313. ravazzi c. 2003 an overview of the quaternary continental stratigraphic units based on biological and climatic events in italy. il quaternario – italian journal of quaternary sciences, 16 (1bis), 11-18. ronchetti f. 2002-2003 la frana di berceto (val taro – appennino parmense). dipartimento di scienze della terra, università degli studi di modena e reggio emilia, unpublished thesis. sturm m. 1979 origin and composition of clastic varves. in: schlüchter c. (ed), morains and varves, balkema, rotterdam, 281-285. tellini c. & chelli a. 2002 antichi movimenti di frana dell’appennino parmense e relazioni con le condizioni paleo-climatiche del tardo quaternario. l’orsaro, 22 (2), 9-20. tellini c. & chelli a. 2003 ancient and recent landslide occurrences in the emilia apennines (northern apennines, italy). proc. workshop on “geomorphological sensitivity and system response”, camerino-modena apennines (italy), july 4th-9th, 2003, 105-114. vescovi p. 1986 l'assetto strutturale della val baganza tra berceto e cassio (pr). acta naturalia de “l'ateneo parmense”, 22, 85-111. vescovi p. 1988 la linea trasversale passo della cisaval parma-bassa val d'enza: 1. sistema trascorrente sinistro nella zona del passo della cisa (prov. di parma). acta naturalia de “l'ateneo parmense”, 24, 221-243. vescovi p. (coord.) 2002 foglio 216 " borgo val di taro" della nuova carta geologica d'italia 1:50.000. servizio geologico d'italia. watson c.s. 1996 the vegetational history of the northern apennines, italy: information from three new sequences and review of regional vegetational chiange. jour. biogeog., 23, 805-841. 143 ms. ricevuto il 25 maggio 2004 testo definitivo ricevuto il 28 settembre 2004 ms. received: may 25, 2004 final text received: september 28, 2004 first remarks on late pleistocene ... imp. giano-martino aasssseettttoo mmoorrffootteettttoonniiccoo ee mmoorrffoossttrraattiiggrraaffiiccoo ddii aallccuunnii ddeeppoossiittii ccoonnttiinneennttaallii pplleeiissttoocceenniiccii ddeell bbaacciinnoo ddeell ppeerrggoollaa--mmeellaannddrroo ((aappppeennnniinnoo lluuccaannoo)) ssaallvvaattoorree iivvoo ggiiaannoo11 && ccllaauuddiioo mmaarrttiinnoo22 1di.s.g.g., università della basilicata, potenza 2dipartimento di scienze geologiche, università della basilicata, potenza riassunto sono stati investigati i rapporti fra morfologia, stratigrafia e struttura di alcuni depositi conglomeratici continentali affioranti nel bacino intermontano del pergola-melandro, ubicato nella zona assiale dell’appennino lucano. gli aspetti geomorfologici, stratigrafici e neotettonici preliminari dell’area sono stati già oggetto di studio da parte di diversi autori che assegnano un’età plio-pleistocenica alla genesi della depressione tettonica. due sottobacini, conosciuti rispettivamente come s. angelo e brienza, separati da un alto strutturale, costituiscono l’intera depressione colmata da alluvioni ben organizzate nel primo caso e da alluvioni più prossimali con carattere fluvio-torrentizio nel secondo. l’evoluzione geomorfologica e sedimentaria del bacino secondo gli autori è stata scandita da diversi episodi deformativi che hanno coinvolto anche le successioni clastiche e la superficie di erosione sommitale terrazzata del riempimento intravallivo. in questo lavoro vengono analizzati i caratteri stratigrafici della porzione sommitale del riempimento clastico continentale del bacino e gli aspetti relativi al loro stato di deformazione in alcuni settori dei due sottobacini. i rapporti tra le principali strutture tettoniche riconosciute e alcune superfici di erosione modellate sia in depositi clastici quaternari sia nel substrato pre-quaternario hanno contribuito a chiarire alcuni aspetti dell’evoluzione morfotettonica quaternaria dell’area. superfici di erosione e/o paleosuoli nelle successioni clastiche analizzate nei pressi di serra murgia longa hanno permesso di differenziare tre unità deposizionali con una diversa organizzazione dei depositi. l’analisi mesostrutturale ha consentito di riconoscere differenti sistemi di faglie, orientati in direzione antiappenninica ed appenninica, che hanno deformato i depositi clastici del pleistocene inferiore. il sistema antiappenninico, privo di espressione morfologica, che disloca i conglomerati del ciclo basale è suturato verso l’alto da un orizzonte più cementato e mostra un’attività tettonica sinsedimentaria. il sistema appenninico disloca sia l’intera successione clastica infrapleistocenica che i terrazzi di erosione sommitali del fondovalle alluvionale denunciando una attività tettonica più recente. un deposito detritico-alluvionale, in facies di conoide prossimale affiorante nei pressi di santa domenica – è costituito da due unità deposizionali separate da una superficie di erosione e da un paleosuolo fagliato. in alcuni punti il deposito più recente della successione alluvionale del pergola-melandro è vistosamente deformato e ruotato contro monte da una faglia ad andamento appenninico. in conclusione i depositi continentali studiati hanno registrato l’attività di alcuni sistemi di faglie nel corso del pleistocene evidenziando un carattere sinsedimentario per alcune, ed una attività recente e verosimilmente sismogenetica per altre, come risulta dagli elementi morfotettonici e stratigrafici riconosciuti nel bacino. abstract the relationships between some morphostructural and stratigraphic features outcropping in the pergola-melandro intermontane basin have been investigated. tectonic events have conditioned the geomorphological evolution of the basin during pleistocene times. a morphological ridge, constituted by pre-quaternary bedrock, separates the basin in two small sub-basins. the first (s. angelo subbasin) is characterized by alluvial deposits with coarse-grained and pelite facies. in the second one (brienza sub-basin) the alluvial system proximal facies crop out. stratigraphic and structural analyses have been carried out in the upper portion of these continental clastic succession. three sedimentary episodes separated by erosional surfaces and/or palaeosoils are recognised. they reflect different morphoclimatic regimes which occurred in early pleistocene. both ne-sw and nw-se trending fault systems deformed the clastic succession. one can observe that a conglomerate horizon seal a ne-sw sinsedimentary fault, whereas the nw-se-trending faults dissect the entire clastic succession and the erosional terraces, middle pleistocene in age. talus cones constituted by breccia deposits outcropping in the santa domenica area show only two depositional episodes separated by red palaeosoils and erosional surfaces. deposits and palaeosoils have been dissected by nw-se-trending faults. furthermore, the breccias have been tilted counterslope by these faults. stratigraphic and morphotectonic relationships suggest a recent tectonic and seismogenetic activity of this fault systems in the axial zone of the southern apennines. parole chiave: morfotettonica, stratigrafia, quaternario, appennino meridionale. keywords: morphotectonic, stratigraphy, quaternary, southern apennines. il quaternario italian journal of quaternary sciences 1166(2), 2003, 289-297 11.. iinnttrroodduuzziioonnee la valle del pergola-melandro rappresenta una delle numerose depressioni intermontane quaternarie, di origine tettonica, dell’appennino lucano. l’area di studio, localizzata nella zona assiale della catena sudappenninica (fig. 1), è limitata dalla dorsale dei monti della maddalena lungo il bordo occidentale, dal monte arioso e cime contigue su quello orientale. il corso d’acqua principale, allungato in senso appenninico, drena verso nord-ovest in direzione tirrenica e confluisce oltre la zona di soglia a valle dell’abitato di s. angelo le fratte (fig. 1) nel fiume bianco, un affluente di basso rango gerarchico del fiume sele. la depressione tettonica è divisa in due sottobacini, attraversati dai torrenti melandro e pergola, denominati rispettivamente s. 290 s. i. giano & c. martino angelo e brienza (lippmann provansal, 1987; santangelo, 1991); questi ultimi sono separati da un alto strutturale modellato in substrato pre-quaternario, orientato in direzione antiappenninica e ubicato poco a nord dell’abitato di brienza in località s. giuliano. secondo i risultati del presente studio la distribuzione areale della successione continentale infrapleistocenica del bacino mostra una continuità planimetrica dei depositi alluvionali s.l. di s. angelo e brienza rivelando – diversamente da quanto ritenuto da lippmann provansal (1987) e santangelo (1991) secondo cui si tratterebbe di due bacini di sedimentazione separati da uno spartiacque morfologico una originaria continuità di drenaggio tra i torrenti pergola e melandro (fig. 1). nell’ambito della ricostruzione litostratigrafica dell’intera successione continentale quaternaria del bacino del pergola-melandro ancora in corso di studio è stata realizzata una analisi di dettaglio della parte sommitale, in prevalenza conglomeratica, del riempimento alluvionale infrapleistocenico del bacino e di alcuni depositi di versante più recenti che hanno messo in luce diverse unità deposizionali separate da paleosuoli e/o superfici di erosione. inoltre, il confronto tra le forme del rilievo e le strutture fragili rilevate alla mesoscala nei depositi continentali ha permesso di riconoscere i principali lineamenti tettonici che hanno interessato l’area nel corso della sua storia morfoevolutiva. i depositi studiati risultano vistosamente deformati da due sistemi di faglie, uno ad andamento antiappenninico con attività tettonica sinsedimentaria ed assenza di espressione morfologica e l’altro appenninico, più recente dei depositi alluvionali infrapleistocenici del bacino; le faglie appenniniche dislocano sia una superficie di erosione sommitale scolpita nei depositi alluvionali del riempimento intravallivo (lippmann provansal, 1987), che brecce di versante, entrambe profondamente incise e terrazzate dai torrenti pergola e melandro e dai loro affluenti. in tal senso la superficie di erosione sommitale può essere considerata come una superficie di appoggio basale per le coperture sedimentarie più recenti sensu carraro (1996). fig. 1 carta geologica ed ubicazione del bacino del pergola-melandro. nel riquadro sono evidenziati i settori investigati. geological sketch map and location of the pergola-melandro basin. in the frame, the part of the basin investigated as shown. 22.. iinnqquuaaddrraammeennttoo ggeeoollooggiiccoo ee mmoorrffootteettttoonniiccoo la depressione tettonica quaternaria del pergolamelandro (santangelo, 1991) si è impostata in corrispondenza del sovrascorrimento fra diverse unità tettoniche generate dalla deformazione di domini paleogeografici mesozoico-terziari nel corso della tettogenesi appenninica (d’argento et al., 1973). l’unità a tetto è rappresentata da successioni carbonatiche di piattaforma mentre quella a letto da unità pelagiche di tipo lagonegrese (schiattarella et al., 2003). risultano coinvolte nella deformazione neogenica anche successioni silicoclastiche mioceniche depositate in bacini satellite e/o di avanfossa sopra le coltri deformate (pescatore et al., 1999). i depositi pliocenici, in questo settore della catena, sono rappresentati da sporadici lembi di sabbie e conglomerati appartenenti al ciclo di ariano nei pressi di monte la conca e serra piani di mauro (di nocera et al., 1982). a partire dal pliocene superiore – pleistocene inferiore, lungo la fascia assiale della catena sudappenninica le strutture contrazionali neogeniche sono state dislocate da faglie trascorrenti orientate in direzione n120°±10°, n50÷60° e n-s (ortolani et al., 1992; cinque et al., 1993; schiattarella, 1998). l’instaurarsi di un regime tettonico estensionale caratterizzato da faglie ad alto angolo ha favorito la parziale riattivazione di vecchie strutture e la neoformazione di faglie con direzione appenninica e/o antiappenninica come dimostrato da evidenze geomorfologiche e strutturali (ortolani et al., 1992) e dalla sismicità (amato & selvaggi, 1993). gli aspetti geomorfologici, stratigrafici e neotettonici del bacino del pergola-melandro sono stati affrontati da lippmann provansal (1987) e santangelo (1991) che descrivono il riempimento continentale del bacino come una potente successione alluvionale in facies fluvio-torrentizia che, nelle aree depocentrali, raggiunge i 180 metri di spessore (fig. 2). il cosiddetto bacino di s. angelo è riempito da depositi alluvionali ben organizzati mentre il bacino di brienza è colmato da alluvioni più prossimali e poco organizzate, con carattere torrentizio. santangelo (1991) attribuisce alla neotettonica infrapleistocenica la genesi del bacino che avrebbe provocato, tra l’altro, il parziale sbarramento del reticolo idrografico. quest’ultimo si sarebbe evoluto con un meccanismo di antecedenza aggradazionale, con sovralluvionamento a monte della soglia e deposizione della successione alluvionale infrapleistocenica (santangelo, 1991), analogamente a quanto avvenuto nella vicina alta val d’agri (di niro et al., 1992). ulteriori episodi deformativi hanno interessato l’intera area condizionando l’evoluzione successiva del bacino. la superficie sommitale del fondovalle alluvionale – di natura erosionale (lippmann provansal, 1987) – è stata in seguito incisa e terrazzata in un unico ordine dall’erosione regressiva del reticolo idrografico. in particolare i terrazzi del fondovalle rappresentano i lembi incisi di un esteso glacis d’erosione poligenico modellato nel corso del pleistocene medio in un regime morfoclimatico freddo (lippmann provansal, 1987); la loro età è quindi posteriore a tale data. questi terrazzi sono, inoltre, dislocati a quote comprese tra 790 e 560 metri s.l.m. dalla tettonica estensionale plio-quaternaria (santangelo, 1991). la stima dei tassi di sollevamento quaternari, rea291assetto morfotettonico e morfostratigrafico ... f ig . 2 p a n o ra m ic a d e ll’ a re a d i st u d io . in p ri m o p ia n o s o n o v is ib il i le s u p e rf ic i te rr a zz a te a l te tt o d e l ri e m p im e n to c la st ic o d e l b a ci n o . p a n o ra m ic v ie w o f th e s tu d y a re a sh o w in g t h e t o p f la tte d e ro s io n a l te rr a c e s o f th e p e rg o la m e la n d ro b a si n . 292 lizzata recentemente lungo la zona assiale della catena da schiattarella et al. (2003), ha interessato anche il bacino del pergola-melandro. per il terrazzo di erosione sommitale è stato calcolato un sollevamento regionale pari a 0.99 mm/a, mentre lo slip rate misurato lungo la faglia bordiera del bacino ha fornito un valore di 0.5÷0.8 mm/a nell'intervallo cronologico 1.8÷1.2 ma. la strutturazione della depressione tettonica del pergola-melandro viene attribuita sulla base di considerazioni regionali all’interazione tra sistemi di faglie ad andamento appenninico ed antiappenninico che hanno registrato locali movimenti transtensivi o transpressivi (ortolani et al., 1992). non è ancora noto se la cinematica di apertura del bacino sia avvenuta in un regime tettonico trascorrente (pull-apart basin) oppure estensionale (graben o half-graben). 33.. aannaalliissii ssttrraattiiggrraaffiiccaa ee rraappppoorrttii mmoorrffootteettttoonniiccii i depositi clastici del bacino del pergola-melandro sono formati da una successione continentale composta da facies variabili localmente; si passa, infatti, dalle alluvioni s.s. di s. angelo, rappresentate da una alternanza argilloso-siltosa con intercalazioni conglomeratiche che verso i bordi diventano dominanti, alle successioni fluvio-torrentizie e detritiche di brienza costituite da conglomerati in assetto massivo e da brecce di versante. sono stati studiati i caratteri litostratigrafici della parte sommitale, prevalentemente conglomeratica, del riempimento clastico infrapleistocenico del bacino (denominato informalmente successione alluvionale del pergola-melandro) per uno spessore di circa 50 metri: questi hanno messo in luce tre distinte unità deposizionali (fig. 3) mentre i rapporti tra le mesostrutture fragili rilevate nei depositi clastici e nel terrazzo sommitale del riempimento intravallivo hanno fornito informazioni utili alla comprensione dei caratteri morfoevolutivi dell’area. l’unità deposizionale basale (ab) – ancora in corso di studio – rappresenta buona parte del riempimento clastico del bacino e viene parzialmente trattata in questo lavoro. essa è troncata da una superficie di erosione che costituisce la superficie di appoggio basale per le due successive unità: quella intermedia (ai) e quella sommitale (as). nei pressi di serra murgia longa sono state riconosciute le due unità più recenti (ai e as rispettivamente in fig. 3) che sono rappresentate dal basso da conglomerati poligenici a supporto di matrice argilloso-sabbiosa che passano lateralmente ad argille siltose grigioverdi contenenti livelli di conglomerati e sabbie. la giacitura discordante del corpo, che immerge a no di oltre 30°, rispetto al terrazzo inciso di quota 630 metri s.l.m. indica un’attività tettonica successiva alla sua formazione. il passaggio al deposito sovrastante (as) costituito da conglomerati massivi, con clasti di natura carbonatica e silicea, a supporto di matrice sabbiosa di colore rosso intenso è marcato da una netta superficie di erosione. si tratta in entrambi i casi di depositi in facies di conoide alluvionale generati in differenti contesti morfoclimatici. l’intera successione è attualmente incisa e terrazzata dal torrente pergola. l’analisi mesostrutturale effettuata nella frazione esclusivamente conglomeratica del deposito dell’unità intermedia (ai) ha fornito i dati sulle faglie ad alto angolo presenti caratterizzate da una cinematica diretta o leggermente obliqua. sono ben documentati i sistemi di faglia orientati in direzione n10÷30°, n60÷80° e n100÷110° (fig. 4), ma risulta più evidente il trend appenninico n160÷170° individuato da coppie coniugate di faglie. e’ stato osservato che il sistema n60÷80° disloca i conglomerati dell’unità basale ma è suturato verso l’alto da un orizzonte più cementato a testimonianza di un’attività tettonica sinsedimentaria (fig. 5). il sistema n100÷110° attraversa invece l’intera successione dislocando di oltre 10 metri il terrazzo sommitale di serra murgia longa che si dipana da circa 760 a 625 metri s.l.m. già interrotto in altri punti da altre scarpate di faglia con rigetti morfologici decametrici. in sezione trasversale queste scarpate mostrano versanti regolarizzati con profilo rettilineo e inclinazione intorno ai 40÷45°; il loro andamento planimetrico, ben evidente in aerofoto, si sviluppa in modo regolare e lineare da un bordo all’altro del terrazzo che attraversano. una ampia fascia di deformazione si osserva nei conglomerati dell’unità basale del torrente fragneto. i clasti, per alcuni metri, sono verticalizzati ed orientati in direzione appenninica (n160÷170°) mentre lateralmente è presente una frattura beante di circa 50÷60 cm con pareti orientate nella stessa direzione e parzialmente riempita da ciottoli del deposito sovrastante. una superficie di erosione tronca i conglomerati infrapleistocenici dell’unita basale (ab) e costituisce la superficie di appoggio basale (carraro, 1996) per un deposito alluvionale più recente ed incastrato morfologicamente nel precedente, ascrivibile seppur dubitativamente al pleistocene superiore? olocene, costituito da ghiaie carbonatiche, di dimensioni metriche e prive di matrice, che passano verso l’alto a sabbie di colore marrone con rari ciottoli centimetrici. si può quindi affermare che il sistema di faglie n60÷80° è stato parzialmente attivo durante la deposizione delle alluvioni del pergola-melandro interrompendo l’attività nel corso del pleistocene inferiore. il sistema di faglie n160÷170° è stato attivo, invece, dopo il modellamento del glacis erosionale mediopleistocenico. nei pressi dell’abitato di brienza, in un taglio artificiale di circa 10 metri (fig. 6), affiora un deposito conglomeratico immergente a nord-est di circa 30÷35° e costituito dal basso verso l’alto: da clasti di natura prevalentemente carbonatica e subordinatamene silicea, a supporto di matrice sabbioso-argillosa marrone e con intercalazioni di lenti sabbiose centimetriche che rappresentano la parte finale dell’unità basale (ab in fig. 3). quest’ultima è troncata a tetto da una superficie di erosione che rappresenta la superficie di appoggio basale di un paleosuolo di spessore metrico costituito da argilla siltosa di colore rosso marrone scuro con pezzame litoide a spigoli vivi di natura carbonatica (pc in fig. 3). un banco conglomeratico più cementato segna l’inizio della successiva unità deposizionale (ai in fig. 3) caratterizzata da conglomerati con clasti di natura carbonatica e silicea, ben organizzati che immergono a nord-est di 8÷10° e passano lateralmente a silt argillosi e sabbie siltose giallastre con intercalazioni di lenti conglomeratiche. l’organizzazione interna del deposito risulta correlabile a quella descritta in precedenza a serra murgia longa ed evidenzia, in questo settore, una continuità negli apporti. una nuova superficie di erosione separa il deposito dall’unità sovrastante (as in fig. 3) rappresens. i. giano & c. martino 293 f ig . 3 s tr a tig ra fia s ch e m a tic a d e l b a ci n o d e l p e rg o la -m e la n d ro ( d a s a n ta n g e lo , 1 9 9 1 , m o d ifi ca to ). l e a re e r iq u a d ra te r a p p re se n ta n o l a p o rz io n e d i su cc e ss io n e i n ve st ig a ta d e lle a llu vi o n i d e l p e rg o la -m e la n d ro . s tr a tig ra p h ic lo g s o f th e p e rg o la -m e la n d ro b a si n ( a ft e r s a n ta n g e lo , 1 9 9 1 , m o d ifi e d ). i n t h e f ra m e , th e p o rt io n o f p e rg o la -m e la n d ro a llu vi a l s u cc e ss io n in ve st ig a te d . assetto morfotettonico e morfostratigrafico ... 294 tata da conglomerati massivi, di natura carbonatica, a supporto di matrice sabbioso-argillosa rossastra. il corpo, spesso da pochi centimetri fino a circa 3 metri, costituisce l’ultimo evento deposizionale del riempimento infrapleistocenico prima della formazione del glacis erosionale (lippmann provansal, 1987) e prima della successiva profonda incisione e terrazzamento ad opera del torrente pergola e dei suoi affluenti a cui seguono episodi di sedimentazione altopleistocenici non oggetto di questa nota. nel suo insieme l’organizzazione del deposito riflette i caratteri sedimentari tipici di un sistema di conoide alluvionale che passava lateralmente ad aree sottoalimentate con scarsa capacità di drenaggio. nei pressi di santa domenica affiora una successione detritico-alluvionale in facies di conoide prossimale (fig. 7). il deposito, inciso da corsi d’acqua di basso ordine gerarchico, mostra due unità deposizionali (denominate di e ds in fig. 3) separate da una superficie di erosione a tratti fossilizzata da un paleosuolo argilloso di colore marrone rossastro scuro spesso circa 50 cm e con al suo interno pezzame calcareo (pd3 in fig. 3). l’intero corpo, che supera i 30 metri di spessore, viene in alcuni punti ruotato contro monte di circa 30° da una faglia ad alto angolo con direzione appenninica. il paleosuolo pd3 è inoltre dislocato di qualche centimetro da una faglia diretta a direzione appenninica. si tratta di due segmenti isolati della faglia principale appenninica che borda sul lato orientale i monti della maddalena e che attraversa l’intero bacino. la prima unità (di in fig. 3) mostra due distinti momenti di aggradazione separati da paleosuoli argillosi di colore marrone rossastro scuro spessi alcuni centimetri (pd1 e pd2 in fig. 3). poche decine di centimetri sopra il paleosuolo pd1 è presente un livello pelitico potente alcuni centimetri costituito da argilla plastica grigio-verde. il deposito, con strati centimetrici, è formato da brecciole a clasti carbonatici e supporto di matrice sabbiosa calcarea di colore bianco; fig. 4 proiezione stereografica (reticolo di wulff, emisfero inferiore) delle faglie rilevate nei conglomerati del pergolamelandro. le frecce indicano il verso di scorrimento del blocco di tetto. stereonet (wulff net, lower emisphere) of the faults measured in the conglomerate of the pergola-melandro basin. the arrows show the hanging wall displacement. fig. 5 affioramento conglomeratico nei pressi di serra murgia longa. la faglia sulla destra è fossilizzata da un livello di conglomerati più cementati mentre quella sulla sinistra taglia l’intera successione. outcrop of the murgia longa conglomerate. a conglomerate bed overlies the fault on the right whereas the fault on the left dissects the entire succession. sono presenti inoltre blocchi isolati di dimensioni metriche. i caratteri litologici riflettono diversi momenti di deposizione legati a fattori climatici nell’ambito di un unico episodio di sedimentazione. una superficie di erosione segna il passaggio al paleosuolo pd3 coperto dai depositi dell’unità successiva (ds in fig. 3) formati da s. i. giano & c. martino brecce con caratteristiche litologiche e deposizionali analoghe a quelle sottostanti. la sommità del detrito è incisa e terrazzata a quote comprese tra 860 e 750 metri s.l.m. e si collega al retrostante versante attraverso un evidente raccordo concavo. a causa della sua posizione decentrata nel bacino il deposito detritico non si correla fisicamente con la successione alluvionale terrazzata del pergola-melandro. le superfici terrazzate modellate nel detrito di versante risultano però incastrate all’interno di alcuni terrazzi erosionali in substrato pre-quaternario posti ad una quota di circa 890 metri s.l.m. che si raccordano – a loro volta – ai terrazzi sommitali della successione alluvionale del bacino. e’ possibile allora considerare il corpo detritico più recente o al massimo coevo dell’ultima unità litostratigrafica riconosciuta nella successione alluvionale infrapleistocenica del bacino (as in fig. 3) collocandosi nella parte medio-alta del pleistocene medio. 44.. ddiissccuussssiioonnee ee ccoonncclluussiioonnii l’analisi stratigrafica e morfostrutturale della porzione sommitale del riempimento alluvionale infrapleistocenico affiorante nel bacino (successione alluvionale del pergola-melandro) ha consentito di chiarire alcuni aspetti sull’evoluzione sedimentaria e morfotettonica recente dell’area (fig. 8). sono state riconosciute tre distinte unità litostratigrafiche (ab, ai e as in fig. 3) separate da paleosuoli e da superfici di erosione. la distribuzione areale dei depositi clastici legati alla seconda ed alla terza unità (ai ed as) ha evidenziato una continuità di drenaggio tra i sottobacini di s. angelo e brienza assente nello stadio di sedimentazione iniziale rappresentato dall’unità basale as (fig. 3). un sistema di faglie orientato in direzione n60÷80° e con attività tettonica sinsedimentaria è stato riconosciuto nei pressi di serra murgia longa dove un orizzonte conglomeratico più cementato fos295 fig. 6 taglio artificiale nei pressi dell’abitato di brienza. sono evidenti le diverse unità deposizionali separate da superfici di erosione e da un paleosuolo. la parete sulla sinistra permette di valutare anche l’inclinazione del deposito rispetto alla superficie terrazzata sommitale. outcrop near brienza town. different depositional episodes separated by erosional surfaces and by a palaeosoil are exposed. dip angle of the succession and top of erosional terrace are shown on the left. fig. 7 apparato detritico nei pressi di santa domenica. talus slope deposits in the santa domenica area. assetto morfotettonico e morfostratigrafico ... silizza un piano di faglia (fig. 5). considerata l’età mediopleistocenica attribuita al modellamento del glacis d’erosione al top della successione alluvionale del bacino (lippmann provansal, 1987), l’intervallo di attività del sistema antiappenninico è confinato al pleistocene inferiore. le faglie rilevate alla mesoscala nei conglomerati infrapleistocenici nei pressi del torrente fragneto confermano l’esistenza già riconosciuta dall’analisi geomorfologica di una fascia di deformazione, caratterizzata da faglie con cinematica diretta o obliqua, orientata in direzione n160÷170°, responsabile della strutturazione del bordo occidentale del bacino e che avrebbe guidato anche la incisione della forra di brienza ad opera del torrente pergola. le faglie ad andamento appenninico tagliano l’intera successione clastica dando luogo a scarpate con rigetti decametrici nei terrazzi sommitali distribuiti a quote comprese tra 790 e 600 metri s.l.m. l’età mediopleistocenica dei terrazzi erosionali del riempimento intravallivo (lippmann provansal, 1987) costituisce il limite ante quem per l’attività di queste strutture. la rotazione contro monte di circa 30° di un corpo detritico più giovane della successione alluvionale del pergola-melandro e la presenza di una faglia che disloca di poche decine di centimetri un paleosuolo nei pressi di santa domenica rappresentano le evidenze morfostrutturali della attività più recente del sistema di faglie appenninico lungo il bordo orientale della dorsale dei monti della maddalena (fig. 8). l’esistenza di paleosuoli fagliati datati con il metodo del radiocarbonio a circa 20.000 anni b.p. da giano et al. (2000) appartenenti ad un deposito detritico recente e ubicati lungo la stessa direttrice strutturale nel bordo orientale dei monti della maddalena consente di ipotizzare un’attività tettonica recente anche per le faglie riconosciute in accordo con la sismicità dell’area (amato & selvaggi, 1993). in conclusione, è possibile affermare che i depositi continentali della successione alluvionale del pergola-melandro hanno registrato l’attività di sistemi di faglie antiappenniniche e con attività sinsedimentaria nel corso del pleistocene inferiore, mentre i sistemi di faglie ad andamento appenninico hanno mostrato una attività tettonica più recente e probabilmente sismogenetica come documentato dalla sismicità dell’area (amato & montone, 1997) e dalle evidenze morfostrutturali e stratigrafiche dei depositi più recenti coinvolti nella deformazione. rriinnggrraazziiaammeennttii gli autori sono grati al prof. m. schiattarella per le interessanti discussioni e per la lettura critica del manoscritto. si ringraziano inoltre i due referee anonimi per i preziosi suggerimenti forniti in sede di revisione del testo. lavoro svolto nell’ambito del progetto di ricerca “evoluzione geodinamica quaternaria dell’appennino meridionale sulla base di dati strutturali e paleomagnetici”, cofin murst 2000-2002 (resp. prof. marcello schiattarella). 296 f ig . 8 s ch e m a m o rf o lo g ic o e s tr a tig ra fic o d e ll’ a re a d i s tu d io . s u lla d e st ra s o n o v is ib ili le t re u n ità d e p o si zi o n a li d e lla s u cc e ss io n e a llu vi o n a le d e l p e rg o la -m e la n d ro s u c u i s i i m p o st a il t e rr a zz o d i e ro si o n e s o m m ita le ; su lla s in is tr a s o n o r ip o rt a ti i d e p o si ti d e tr iti ci p iù r e ce n ti te rr a zz a ti e s o sp e si r is p e tt o a l f o n d o va lle a tt u a le m a c o n u n e vi d e n te r a cc o rd o c o n ca vo r is p e tt o a l r ili e vo a lim e n ta to re . m o rp h o lo g ic a l a n d s tr a tig ra p h ic b lo ck d ia g ra m o f th e s tu d y a re a . o n t h e r ig h t th e t h re e d e p o si tio n a l u n its o f th e p e rg o la -m e la n d ro a llu vi a l su cc e ss io n w ith a b o ve t h e t o p e ro si o n a l te rr a ce ; o n th e le ft t h e t e rr a ce d r e ce n t b re cc ia s w ith a c o n ve x sl o p e p ro fil e t o w a rd t h e m o u n ta in . s. i. giano & c. martino llaavvoorrii cciittaattii amato a. & montone p. 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(1992) – primi dati sull’evoluzione geomorfologica e sedimentaria del bacino dell’alta val d’agri (basilicata). studi geologici camerti, vol. spec. 11999922//11, 257-263. di nocera s., russo b. & torre m. (1982) – i depositi marini del ciclo pliocene inferiore-medio nei dintorni di vietri di potenza. rend. acc. sc. fis. mat., 4455, 87-105. giano s.i., maschio l., alessio m., ferranti l., improta s. & schiattarella m. (2000) radiocarbon dating of active faulting in the agri high valley, southern italy. journal of geodynamics, 2299, 371-386. lippmann provansal m. (1987) l’apennin meridional (italie): etude geomorphologique. these de doctorat d’etat en geographye physique, université d’aix-marseille. ortolani f., pagliuca s., pepe e., schiattarella m. & toccaceli r.m. (1992) active tectonics in the southern apennines: relationships between cover geometries and basement structure. a hypothesis for a geodynamic model. igcp nº 276, newsletter, 55, 413419. pescatore t., renda p., schiattarella m. & tramutoli m. (1999) stratigraphic and structural relationships between meso-cenozoic lagonegro basin and coeval carbonate platforms in southern apennines, italy. tectonophysics, 331155, 269-286. santangelo n. (1991) evoluzione stratigrafica, geomorfologica e neotettonica di alcuni bacini lacustri del confine campano-lucano (italia meridionale). tesi di dottorato in geologia del sedimentario, iii ciclo, università “federico ii” di napoli, 1-109. schiattarella m. (1998) quaternary tectonics of the pollino ridge, calabria-lucania boundary, southern italy. in: holdsworth r.e., strachan r.a. and dewey j.f. (eds), "continental transpressional and transtensional tectonics". geological society, london, vol. spec., 113355, 341-354. schiattarella m., di leo p., beneduce p. & giano s.i. (2003) – quaternary uplift vs tectonic loading: a case-study from the lucanian apennine, southern italy. quaternary international, 110011--110022, 239-251. 297 ms. ricevuto il 24 giugno 2003 testo definitivo ricevuto il 25 novembre 2003 ms. received: june 24, 2003 final text received: november 25, 2003 assetto morfotettonico e morfostratigrafico ... imp.bersezio& aquifer architecture of the quaternary alluvial succession of the southern lambro basin (lombardy italy) riccardo bersezio1, fabrizio pavia1, mariangelo baio2, alfredo bini1, fabrizio felletti1 & cecilia rodondi1 1dipartimento scienze della terra, via mangiagalli 34, 20133 milano e-mail: riccardo.bersezio@unimi.it 2aquater, via emilia, san giuliano milanese (mi) abstract: bersezio r. et al., aquifer architecture of the quaternary alluvial succession of the southern lambro basin (lombardy italy). (it issn 0394-3356, 2004). aquifer stratigraphy of the sector of the pleistocene – holocene alluvial plain of lombardy, run by the lambro valley system south of milan, has been reconstructed on the basis of geological mapping at 1:10.000 and subsurface interpretation and correlation of more than 150 among water wells, boreholes and deep excavations. the middle (?) – late pleistocene sedimentary evolution of this sector includes four major progradation cycles of alluvial depositional systems that migrated from the alpine northern side towards the axial palaeo-po depositional system. these cycles were governed by pleistocene glacial cycles, in combination with ramp-folding of the san colombano – salerano apenninic anticlines and minor uplift of the alpine side. every major cycle is soled by an erosion surface, and is shaped by minor fining upward sequences. both major and minor sequences record at first the advance of coarse-grained units (distal braided alluvial fan or sandy braid plain) which fringe-out south-eastwards into meandering fluvial systems, and are replaced upwards by alluvial plain fines, which close the sequences. physical stratigraphy and geomorphology, analysis of facies associations, characterisation of gravel composition, radiocarbon dating on 4 peat and plant relic samples and findings of transported artefacts allowed the correlation of the four cycles with the regional evolution. the post glacial meandering depositional systems of the deeply entrenched lambro valley system (unit 4, holocene; unit 5, historical), are cut into the braided stream to meandering depositional systems that developed during l.g.m. times, at present outside the lambro valley (unit 3, late pleistocene). these represent the uppermost aquifer unit, i.e. the phreatic – non saturated zone. the underlying unit 2 (late pleistocene) can be correlated with the besnate allogroup, and therefore developed during the corresponding glaciations. it is formed by three stacked sequences, controlled by glacial cycles, which are deeply scoured into the lowermost succession that could be studied (unit 1 middle ? – late pleistocene ?). it represents the most important and permeable intermediate aquifer unit, that is only partly confined by the flood-plain fines of the uppermost sub-unit 2c. riassunto: bersezio r. et al., architettura degli acquiferi nella successione alluvionale quaternaria del bacino del fiume lambro (lombardia, italia). (it issn 0394-3356, 2004). nella pianura padana la conoscenza della geologia delle successioni continentali quaternarie, costituisce la base per la realizzazione dei modelli idrostratigrafici, di gestione delle acque sotterranee e per la programmazione della tutela e del risanamento ambientale. a questi fini è critica la comprensione dell’architettura deposizionale a scale diverse, sia per l’elaborazione di schemi idrostratigrafici regionali, sia per la modellazione del flusso e del trasporto degli inquinanti. in questa prospettiva la valle del lambro, a sud di milano, offre un caso di interesse generale per: 1) le relazioni tra acque superficiali fortemente compromesse ed acque sotterranee, 2) l’architettura deposizionale alluvionale altamente eterogenea, 3) la buona disponibilità di dati di sottosuolo. si è pertanto avviato un progetto di studio stratigrafico-sedimentologico e geofisico, cui farà seguito la modellazione dell’eterogeneità degli acquiferi a diverse scale. vengono qui presentati i risultati della ricostruzione geologica ed idrostratigrafica relativa al settore compreso tra melegnano (a nord) e s.angelo lodigiano (a sud), sulla base del rilevamento in scala 1:10.000 e dello studio stratigrafico e petrografico di affioramenti, sondaggi e pozzi per acqua (173 punti di osservazione su un’area di circa 60 km2, con profondità di indagine di 100 m). l’area in studio si sviluppa nella pianura lombarda meridionale, caratterizzata da pendenze medie della topografia minori di 1.5‰, dall’approfondimento degli alvei fluviali attuali, che decorrono entro scarpate di terrazzo di altezza decametrica e dalla presenza di un rilievo collinare di origine tettonica, con sollevamento attivo durante il pleistocene (colle di san colombano), poco a nord del livello di base del po. le tracce meandriformi dell’idrografia attuale e dei paleoalvei sono scolpite nella superficie del cosiddetto “livello fondamentale della pianura”. sono state suddivise cinque unità deposizionali informali, caratterizzate su basi stratigrafiche, petrografiche e di facies, che comprendono, dal basso: unità 1, sistemi deposizionali sabbioso–argillosi, con caratteri indicativi di ambiente fluviale meandriforme, con tetto individuato tra 50 e 70 m di profondità, da nord verso sud. essa comprende sequenze di facies fining-upwards, costituite da sabbie medie e fini, raramente ghiaiose, passanti a sedimenti fini, argilloso-limosi, con paleosuoli organici bruni. l’unità 2, sistemi deposizionali ghiaioso – sabbiosi, comprende due sub-unità ghiaioso–sabbiose (2a e 2b), incontrate dalle perforazioni a profondità di 20-25 m, interpretabili come tipiche di un ambiente di conoide alluvionale distale a canali intrecciati. esse passano a tetto ad una terza subunità (2c), sabbioso–limoso–argillosa, organizzata in sequenze di facies fining-upwards chiuse a tetto da argille organiche e paleosuoli bruni mal drenati, interpretabile come il prodotto della transizione tra un sistema di deposizione a canali intrecciati (settentrionale) ed un sistema di deposizione meandriforme (meridionale). le datazioni 14c relative alla base dell’unità 2c hanno fornito età (non calibrate) comprese tra 23.145± 340 a bp e 24.145±160 a bp; il tetto della stessa unità è stato datato a 22.035±300 a bp. le ghiaie che appartengono a questo gruppo di unità hanno composizione caratterizzata dall’abbondanza dei clasti metamorfici e magmatici, ampiamente prevalenti sui clasti sedimentari di provenienza sudalpina locale. l’unità 3, sistemi deposizionali sabbiosi, è costituita da sedimenti localmente affioranti, organizzati in due sub-unità (3a e 3b) formate da lenti sabbioso-ghiaiose e/o sabbiose, sviluppate tra il piano campagna e la profondità di 10-15 metri. a queste si associano sedimenti fini limoso-argillosi bruni, con paleosuoli organici intercalati. questi corpi, talora delimitati da orli relitti di terrazzi di altezza metrica, comprendono i depositi dei corsi d’acqua meandriformi delle paleovalli del sillaro (ad est del lambro) e del paleoalveo carpiano-bescapè (ad ovest del lambro). questi sedimenti vengono a contatto, per mezzo di una superficie erosionale inferiore, sia con i sedimenti fini a tetto dell’unità 2c, sia con le sabbie e ghiaie ad essi sottostanti (unità 2c inferiore e 2b). il tetto dell’unità 3a è stato datato in un punto di misura compreso tra il dominio del lambro e quello del sillaro, a 18.785±230 a bp, calibrabile ad età comprese tra 19.909 e 20.785 cal bc. le unità 4 e 5, sistemi deposizionali antichi e post-glaciali della valle del lambro, sono costituite da sedimenti di ambiente fluviale meandriforme, organizzati in unità minori, contenute all’interno delle scarpate che delimitano questo sistema vallivo. si tratta di depositi sabbiosi e ghiaioso-sabbiosi (barre di meandro e ventagli di rotta) associati a subordinate successioni di sedimenti fini, limosi ed argillosi, di argine, piana di esondazione e di abbandono di canale. questi sedimenti si distribuiscono su tre ordini di terrazzo, sopraelevati più di 10 m rispetto alla quota dell’alveo di massima piena attuale del lambro. il terrazzo più recente, ancora sopraelevato fino ad oltre 6 metri sulla piana attuale, rappresenta le fasi di deposizione avveil quaternario italian journal of quaternary sciences 17(2/1), 2004, 361-378 362 r. bersezio et al. 1 introduction modelling groundwater flow in alluvial aquifers requires the preliminary elaboration of conceptual models of subsurface geology, including hydrostratigraphic properties of the sediments. the hydrostratigraphic models must take into account the geometry of aquifer/aquitard/aquiclude units, their hydrodispersive properties, their connectivity and must include the evaluation of incertitude on the parameters (see for instance anderson, 1997 or huggenberger & aigner, 1999, with references therein). a multidisciplinary approach is therefore necessary, by the integration of geological, sedimentological, geostatistical and numerical methods, with emphasis on the geological reconstruction. we apply such an approach to the study of aquifer dynamics of the southern lambro valley, south of the milan conurbation, close to the confluence with the main axial fluvial system of the present day lombardy plain, the po river (fig. 1). the final goal is that of elaborating the hydrostratigraphic model of the main aquifer groups (regione lombardia-eni, 2002), with attention to the shallowest hydrostratigraphic units of middle p.p. upper pleistocene age, in the alluvial plain between ticino and adda rivers, south of milan (figs. 2 and 3) and of the holocene to recent units above them. this will provide the basis for modelling groundwater flow through these aquifer groups and their confining layers. the research is in progress, following three steps: a) survey and elaboration of the geological model, incorporating geometrical, stratigraphic, petrographic and facies information at several scales (i.e. from surface mapping to outcrop sedimentology, boreholes, well and log analyses); b) elaboration of the hydrostratigraphic model, which will be inclusive of the semiquantitative geological model and of the geostistical 3d reconstruction, after which the evaluation of incertitude on estimates of distribution of hydrodispersive properties of the individual units will be possible; c) numerical modelling of flow, starting with the attempts to upscale local properties to the wider regional scales. here we present the semiquantitative geological and hydrostratigraphic model. the results of numerical modelling of groundwater flow will be addressed elsewhere. nute con certezza in tempi storici, databili per il sistematico ritrovamento di frammenti di laterizi e manufatti, da romani a rinascimentali, embricati nelle forme di fondo ghiaiose (sub-unità 5b). la composizione delle ghiaie delle unità 3, 4 e 5 differisce fortemente dalle sottostanti, per la minima quantità di litici metamorfici e cristallini in genere, per il grado di alterazione di questi ultimi, che ne suggerisce il riciclo, e per la dominanza dei clasti sedimentari provenienti dalle unità mesozoiche sudalpine delle prealpi lombarde. sulla base della ricostruzione stratigrafica e deposizionale è stato realizzato un primo modello geometrico della successione pleistocenica superiore, che consente di prevedere e quantificare l’estensione e la localizzazione delle unità limoso-argillose (acquitardi) e dei principali corpi ghiaioso-sabbiosi (acquiferi). il modello consente una stima del grado di connettività verticale ed orizzontale tra unità acquifere diverse, fornendo una prima approssimazione relativa alle relazioni tra acque superficiali e prima falda (o “gruppo degli acquiferi a”, eni-regione lombardia 2002). l’evoluzione geologica ricostruita tra il pleistocene superiore e l’attuale, evidenzia due cicli di progradazione della parte distale di un sistema deposizionale di conoide alluvionale settentrionale (unità 2a-2c), su un sottostante sistema fluviale a canali stabili e trasporto misto, verosimilmente di tipo meandriforme (unità 1a-b). l’insieme di questi sistemi deposizionali era alimentato da valli in grado di drenare la catena alpina fino allo spartiacque. il sistema deposizionale dell’unità 3 appartiene verosimilmente all’ultimo massimo glaciale (l.g.m.), mentre le unità 4 e 5 rappresentano le unità post-glaciali, sviluppatesi durante l’olocene, quando la presenza dei laghi pedealpini ed il mutato quadro morfo-climatico, determinarono la prevalenza dell’alimentazione locale dalle prealpi, l’ampliamento verso nord dei sistemi deposizionali meandriformi, l’avulsione (sillaro, paleoalveo carpiano bescapé) e/o il rapido approfondimento (lambro, lambro meridionale) delle valli fluviali. key-words: alluvial sediments, aquifer sedimentology, hydrostratigraphy, quaternary, lombardy. parole chiave: idrostratigrafia, lombardia, quaternario, sedimenti alluvionali, sedimentologia degli acquiferi. fig.1 location map of the lambro valley system and study area. the external thrust fronts of the apennines are indicated with bold ornamented triangles; the most external thrust front of southern alps is ornamented with empty triangles. the study area is framed in white. ubicazione del sistema vallivo del lambro e dell’area in studio. i fronti esterni dei sovrascorrimenti appenninici sono indicati con triangoli neri; i fronti esterni sudalpini sono indicati con i triangoli bianchi. l’area in studio è riquadrata in bianco. 2 regional geology of the lambro area the lambro valley is entrenched into the alluvial plain of southern lombardy (fig.1), which is characterised by a very low slope gradient (less than 1.5‰) towards the po base level. the present-day fluviatile network, south of milan, is confined within narrow terraced valleys, bounded by scarps which are 5 30 m in height. at present the lambro valley runs across the area between the major valleys of ticino (west) and adda (east). the catchment areas of these two rivers reach the core of the alps, crossing the sedimentary south-alpine nappes, their variscan metamorphic basement units and the metamorphic alpine nappes of the central alps, just north of the insubric line. downstream their mountain course, two large alpine lakes (verbano and como lakes) started to sieve detritus fed from the internal alps, since post-glacial times. on the contrary, the lambro catchment is much smaller (similar to the olona and seveso basins west of it), reaching at present only the southernmost reliefs of the south-alpine edifice, where only mesoand cenozoic 363aquifer architecture of... rocks are exhumed. outside and above the holocene valleys, south of milan, an abandoned fluviatile network is sculptured into the so-called "livello fondamentale della pianura" (see castiglioni & pellegrini, 2001; marchetti, 2001 with references therein). this consists of several groups of nw – se meandering traces bounded by low height scarps (always less than 5 m in height), which show a marked change in strike downstream (i.e. southward), to a wnw – ese average direction (bersezio, 1986). these relics of abandoned rivers are sometimes run by underfit streams with 2nd order meanders (e.g. roggia barona and colatore lissone, west of the lambro river, sillaro underfit stream, east of the same; veggiani, 1982; bersezio, 1986). the san colombano hill rises at the southern end of the lambro valley (fig. 1). it developed as a consequence of tectonic uplift of an apenninic anticline, which deformed at least the lower pleistocene and probably also the middle pleistocene sediments (desio, 1965; ariati et al., 1988; alfano & mancuso, 1996; tellini & pellegrini, 2001; fantoni et al., 2003 with references). fig.2 topography of the study area and index map of the data points. equidistance among isohypse is 2 m. schema topografico dell’area in studio ed ubicazione dei sondaggi, pozzi, affioramenti e sezioni stratigrafiche. l’ equidistanza è di 2 m. 364 the se-verging fluviatile network of southern lombardy is tributary of the axial fluvial system, about e-w trending, i.e. the present-day and palaeo-po, which drains the nappe systems of the western alps and north-western apennines, up-current in respect to the lambro confluence. the deep subsurface geology of the po plain of lombardy is portrayed mostly by the seismic and well data, which are property of the oil companies. the tectonic substratum of the plio-pleistocene succession is formed by the external south-verging fronts of the southalpine fold and thrust belt, involving the meso cenozoic formations (milan belt of laubscher, 1985; see also pieri & groppi, 1981; cassano et al., 1986). in the central po plain, at the tip of the south-alpine thrusts, gentle anticlines are shaped within the tertiary clastic wedges, (“southernmost po plain structures”, i.e. corneliano, caviaga, soresina structures; bersezio et al., 2001; fantoni et al., 2003). these folds, which are offset by the northward propagation of the youngest external front of the north-verging apenninic thrusts, were deformed after deposition of the syntectonic lower messinian units and were sealed by the uppermost messinian lower pliocene sediments (fantoni et al., 2001). since the latest messinian, the evolution of the southalpine front was therefore controlled mostly by flexuration of the po plain foreland, due to emplacement of the apenninic tectonic load, which resulted in a 5 6° southward dip (pedealpine homocline; pieri & groppi, 1981). tectonic activity on the apenninic side lasted until pleistocene, as it is documented by uplift of the san colombano al lambro and salerano structures, which involve the lower (and middle?) pleistocene sediments (alfano & mancuso, 1996; fantoni et al., 2003). the quaternary terrigenous succession developed above the pliocene, deep marine units. it is formed by a clastic succession, at places more than 700 m thick, which shows a large-scale regressive trend, from the top of the pliocene deep water units, to the pliocene – middle pleistocene shelf and deltaic sediments and finally to alternating coarse and fine-grained alluvial units (middle – upper pleistocene) (dondi & d’andrea, 1986; regione lombardia eni, 2002, with references therein). based on seismic and well data of eni’s property, this large-scale stratigraphic architecture has been correlated to the northwards propagation of apenninic thrusts, which forced the fan-delta of the palaeo-ticino, adda, and apenninic rivers and the central palaeo-po deltaic apparatus, to prograde, filling the former marine basin. at the site of the present-day lambro valley system, the latest shallow shelf and delta sediments should be of early middle pleistocene age (older than 0.87 ma; muttoni et al., 2003). since that time, fluviatile and glacio-fluvial sediments, mostly controlled by climatic/eustatic cycles and subsidence rates, spread over the study area, building a sand – gravel succession up to 100 m thick. its lower part has been described by regione lombardia – eni (2002) as arranged in two main fining upward sequences, which are covered by an upper, coarse grained, non – cyclic unit of late pleistocene age. in the recently proposed hydrostratigraphic classification of regione lombardia – eni (2002), the latter coarse grained unit represents the shallowest aquifer group a, which overlays the cyclical sequences of aquifer group b. both these groups correspond to the traditional aquifer of martinis & mazzarella (1971), and include the three aquifers (“lithozones”) recognised by avanzini et al. (1995) and francani (2001). at present no other modern stratigraphic classification, in terms of allostratigraphic units or ubsu (nacsn, 1983; issc salvador, 1987), based on basin-scale correlations with glacial and glacio-fluvial units, is available. 3 methods the geological model of the middle (p.p.) upper pleistocene sediments of the lambro valley has been obtained after 1:10.000 geological mapping of an area of about 120 km2 (only a part, as large as about 50 km2 is represented in fig. 3), and subsurface analysis based on 173 points among excavations, natural outcrops, water wells and boreholes (fig. 2). some wells attain a depth of about 100 m below the topographic surface, but the majority of boreholes reach a maximum depth of some 50 m. this holds also for the closely spaced borehole transect, drilled for the tav project (high capacity railway). these subsurface data allow a more detailed study for the stratigraphic units which form aquifer group a than for the underlying group b, which is not the prime objective of this work. stratigraphic analysis was based on identification, hierarchization and correlation of the discontinuities which frame the different rank depositional units (sensu miall, 1996). in order to integrate surface and subsurface data we adopted a simplified classification for ranking discontinuity surfaces and depositional lithosomes: 1st order surfaces frame 1st order units of the rank of the depositional systems (i.e. associations of major valley/channel fills and correlated levee, crevasse splay and flood plain areas where present); these surfaces are represented in the field by the major terrace scarps and in cross-section (outcrops or subsurface correlation grid and borehole stratigraphy) by surfaces that intersect and/or collect all the other stratigraphic boundaries, framing several stacked minor sequences or bedsets; 2nd order surfaces frame units of the rank of depositional elements (for instance, fining upwards sequences of point bar accretion within meandering channels); these are recognised in outcrops and boreholes; in the latter case they are represented by gravel sand bedsets with a lower sharp boundary above finer grained units and/or silt mud intervals; in the cross-sections their lower boundaries do not cut across the 1st order surfaces; 3rd order surfaces frame units of the rank of architectural elements (e.g. macroforms or minor channel fills); they are easily recognised in outcrops and correspond to the individual bedsets in boreholes, framed by boundaries which are cut by, or merge with, the 2nd order surfaces. thorough facies identification and coding could be applied only at outcrop observations. in this case we adopted miall's (1996) classification, slightly modified to specify the grain size mixtures (tab. 1). the study of wells and boreholes was based on a purely textural classification and encoding of sediments (tab.1), when only disturbed samples were available. a more complete coding, including also sediment structure, could be adopted in the cases of undisturbed borehole samples r. bersezio et al. 365 fig.3 geological map of the study area. the two sketches represent 1) a general stratigraphic cross – section located along the a-a’ trace; 2) line drawing of pit exposure of sub-unit 5b. carta geologica dell’area in studio. i due schemi rappresentano: 1) schema dei rapporti stratigrafici ricostruito attraverso la sezione aa’; 2) rappresentazione in affioramento dei caratteri della sub-unità 5b. aquifer architecture of... 366 (cohesive sediments and rare cores). compositional analysis of gravels was used to support correlations and to separate provenance of clasts from regional or local sources. some 70 samples of gravel were collected, both in outcrops and boreholes, in the size range of -3φ to -5φ, for classification and counting of at least 100 pebbles for sample. we used these data as a qualitative tool to characterise the different depositional units and to assist correlations. radiocarbon age determinations on 4 samples of peat, organic soils and plant relics provided dating of the bases of the youngest upper pleistocene units. artefact fragments, which were deposited like clasts in fluvial bedforms, added age information on the holocene, historical units. subsurface mapping of 1st order boundaries between the major stratigraphic units was obtained after ordinary kriging, assisted by variogram structural analysis (matheron, 1969). 4 depositional architecture of the southern lambro basin five 1st order depositional units, bounded by 1st order surfaces, build the alluvial architecture of the middle pleistocene (p.p.) holocene succession, down to about 100 m below the topographic surface, corresponding to aquifer groups a, b and probably uppermost c (regione lombardia – eni, 2002). we numbered them starting from the deepest (unit 1) and in this order they are described in the subsequent paragraphs. the top surfaces of units 3, 4 and 5 are assembled to build the present-day topography (figs. 3 and 4). units 1 and 2 are subsurface units with no relations with the present day geomorphology. only the top of unit 2 is rarely exposed by the lambro terrace scarps or by the deepest quarry excavations. 4.1 subsurface units unit 1 – sandy – clayey depositional system unit 1 (fig. 4) is the lowermost subsurface unit which was crossed by the available boreholes and wells, and consists of sand, silt and clay facies, arranged in fining upward sequences. unit 1 gets progressively more sand-rich from the base upwards. it develops between a maximum top elevation of 45 m and a minimum base elevation of -20 m above sea level (figs. 5 and 6). its lower boundary is a 1st order discontinuity surface, represented by the sharp contact of sandy layers above thick, grey, silty-clay deposits, which deepens southwards from –10 to –20 m a.s.l. the top boundary deepens from north to south (i.e. from melegnano to s.angelo lodigiano; fig. 2 and fig. 5, sections 3 and 11), from 45 m a.s.l. to about 10 m a.s.l., being dissected by an erosion surface. unit 1 is formed by two subunits (1a and 1b; figs. 4, 5, 6), separated by a silt-clay interval. they are both formed by stacked 2nd order sequences, up to 10 m thick, with fining upward trends. each minor sequence develops above silts and clays, with a lower sharp boundary and includes a lower grey to yellowish sand unit, sometimes with gravel divisions (csg, ms and fs facies associations; tab. 1 and tab. 2); it is progressively covered by very fine sands and silty clays (vfs, sl, cl, c facies), sometimes cemented, with intervening dark organic soils and some peat. the sand facies associations form flat lens-shaped bodies, with longitudinal (about n-s) length of hundreds of meters and transversal width (about e-w) of tens of meters. a thinning of these bodies corresponds to a facies transition towards sand/silt-clay, thin bedded alternation. the fine-grained sequence which separates sub-units 1a and 1b has an average thickness of about 10 m and is present throughout the entire area except for the casalmaiocco zone (fig. 2; fig. 5, section 3), where it is eroded and replaced by the lowermost sand-body of sub-unit 1b. it is characterised by thin-bedded alternating fs, ls and lc facies, with peat layers and greygreen palaeosoils. differently, at the top of sub-unit 1b only discontinuous lenses of fines are present, also due to truncation at the top. geometry of sedimentary bodies and sediment assemblage of unit 1 point to a mixed – load fluviatile depositional system, with stable channel-fill depositional elements (lens-shaped sand-bodies forming 2nd sediment textures code sediment structures codes (all observations) (outcrops, excavations, pits) gravel g normal graded n sandy gravel gs inverse graded i gravelly sand sg horizontal parallel laminated h sand s low-angle laminaled l silty sand sl planar cross laminated p clayey sand sc trough cross laminated t sandy silt ls small scale trough cross lam. r silt l clayey silt lc additional textural codes clayey-sandy silt lcs very fine vf silty clay cl fine f sandy clay cs medium m gravelly clay cg coarse c clay c very coarse vc peat p tab.1 sediment classification and facies encoding used to describe surface and subsurface units. classificazione dei sedimenti e codifica di facies utilizzata per descrivere le unità in superficie e nel sottosuolo. r. bersezio et al. order sand-silt fining-upwards sequences, soled by low-rank erosion surfaces and capped by organic-rich sediments), crevasse splay (and possibly levee?) depositional elements (isolated thin bedded sand-silt lenses, thin-bedded clay-silt-sand alternations) associated with humid flood plain deposits (organic-rich silt-clay facies with alluvial-type palaeosoils). in addition to these features, the horizontal and vertical cross-cut relations among sand-bodies suggest a deposition dynamics governed by lateral migration, channel truncation/abandonment and channel avulsion. it is therefore suggested that sub-units 1a and 1b represent two stages of evolution of a meandering river depositional system, even if well data do not allow the recognition of the lateral accretion units. sediment load was medium sand and fines, with minor fine gravel in the lower stage, coarse sand with gravel and fines in the upper one. the first migration of a meandering channel system (1a) was followed by the establishment of a wide flood plain, where soil could form over flat and stable surfaces, due to either major avulsion or backstepping of the fluvial system as a consequence of rising base-level. after the scouring of an erosion surface, a new south-eastward migration of the depositional system, with coarser sediments, occurred (sub-unit 1b). the n-s sections of fig. 5 show the facies transition that occurs in less than 15 km towards the se, within both the sub-units, from sand-dominated and thickbedded towards fine-dominated and thin-bedded facies associations. 367 fig.4 middle pleistocene – holocene stratigraphy of the lambro basin, based on surface data, water wells and boreholes. location of the n-s cross section is in fig. 2. gravel composition of the stratigraphic units is reported in the low right insert. stratigrafia della successione del pleistocene medio p.p. – olocene nella zona del lambro, basata sui dati di superficie e di sottosuolo. l’ubicazione della sezione stratigrafica e dei sondaggi è riportata in fig. 2. l’inserto in basso a destra presenta la composizione delle ghiaie di 4 delle 5 unità stratigrafiche studiate. aquifer architecture of... 368 f ig .5 l o n g it u d in a l c ro ss s e c ti o n s (a b o u t n -s ) a c ro ss t h e l a m b ro a re a ( lo c a ti o n in f ig s. 2 a n d 3 ). s e zi o n i s tr at ig ra fic h e lo n g it u d in al i ( c ir c a n -s ) n e lla z o n a d e l l am b ro . l ’u b ic az io n e è r ip o rt at a n e lle f ig . 2 e 3 . r. bersezio et al. unit 2 – gravel sand depositional system unit 2 (fig. 4) is a subsurface unit, whose top develops between 85 m and 45 m a.s.l (north) and base between 62 – 10 m a.s.l. (south), with a thickness ranging 13 – 52 m. it consists of gravel and sand bodies, with minor fine grained layers (mostly silt, rare or no clay), which form three sub-units (from bottom to top 2a, 2b and 2c). only the uppermost one (2c) crops out locally in the deepest scours of the lambro valley; it presumably corresponds to the sand-gravel units which are exposed at the topographic surface of the “livello fondamentale della pianura” just north of the study area (strini, 2001; bini et al., this volume). the stacking of sub-units 2a and 2b determines a clear coarsening upwards trend, which is followed by two fining upwards minor sequences, corresponding to sub-unit 2c). the lowermost sub-unit 2a develops above a lower discontinuity which deepens southwards, deeply dissecting unit 1. in the northern sector of the study area the sub-unit consists of sands and gravelly sands (facies association is presented intab. 2) stacked in non-cyclical bedsets, up to 10 m thick, which alternate with thin and discontinuous fine sand-silt layers. south of the salerano – lodi vecchio area (fig. 2, and fig. 5) a transition to stacked fining upwards sequences, up to 10 m thick with sand silt facies association occurs (tab. 2; fig. 5). subunit 2b is the coarsest lithosome, formed by coarse and massive gravel bodies, up to 10 m thick, with minor sand layers (see facies association in tab. 2). the gravel bodies are rarely separated by grey – brown silt and mud layers and possibly palaeosoils. in the same northern sector, as referred to just above, sub-unit 2b merges with sub-unit 2a, forming a unique gravel body, up to 30 m thick. the two subunits deepen and get progressively separated southwards, owing to the facies transition towards sand – silt fining upwards sequences, which is observed also for sub-unit 2b. the top of the gravel body is sharp and locally shows weathering profiles, which develop on some metres in thickness (munsell colours 7.5yr5/6, 5yr5/6). sub-unit 2c is formed by one (south) or two (north) fining upwards sequences (up to 15 m thick) of dark grey, coarse middle sand, silt to mud facies (tab. 2; figs. 5 and 6), frequently capped by organic-rich palaeosoils and some peat layers, with a total thickness ranging from 30 m to 3 m, the latter case due to top truncation at the base of units 3 to 5. the exposed sections of this sub-unit show that these sequences are formed by large-scale, trough cross-laminated sands in 369 fig.6 – transversal cross sections (about e-w) across the lambro area (location in figs. 2 and 3). sezioni stratigrafiche trasversali (circa e-w) nella zona del lambro. l’ubicazione è riportata nelle fig. 2 e 3. aquifer architecture of... association with planar, high-angle, cross-laminated sands and low-angle to sub-horizontal laminated sands (tab. 2). this association is frequently covered by alternating, thin-bedded, rippled fine sands and laminated to massive silt and silty mud (tab. 2). a facies transition occurs southwards, towards more mud-rich and thinbedded successions (fig. 5, sections 3 and 11). the upper part of sub-unit 2c (figs. 5 and 6) is represented by a widely distributed and continuous succession of laminated to massive, fine grained facies (silty and sandy mud, muddy silt), frequently interbedded with organic-rich palaeosoils and some peat. lenses of grey, laminated to massive mud occur recurrently; they contain plant relics, sometimes metre-sized, continental gastropods and other molluscs. within these fine grained facies association, decimetre-thick sand lenses are present. gravel composition of sub-units 2 a, b, c is quite homogeneous, with rare exceptions, as it is shown in fig.4. excluding the ubiquitous and uniformly distributed quartz pebbles, crystalline rock fragments are almost invariably dominant on sedimentary rock pebbles, with some fluctuations of the relative proportions. the most abundant rock clasts are gneisses and micaschists, with some phyllites and slates (up to 50 % in some samples), invariably associated with igneous rocks (up to 15 %), which include granitoids, granodiorites, rhyolites and intermediate to basic porphyritic volcanites. rare green metabasite fragment and serpentinite complete the crystalline rock composition. sedimentary rock pebbles are never more abundant than 20%; they are mostly represented by limestones, cherts, sandstone-siltstones (among which the collio – verrucano, the cretaceous flysch and the gonfolite sources are easily recognised), rare marlstones. they can be generally correlated with the southalpine sedimentary cover, with no clear indications of apenninic or other alpine provenance. some samples of plant fragments, collected in one temporary exposure due to excavations and in two boreholes, yielded radiocarbon ages relative to sub-unit 2c. its lower sandy succession has been dated between 23.145+/340 a bp. (fig. 6, section 1) and 24.620+/160 a bp. (fig. 5, section 4); these non-calibrated ages are realistically close to the age of the 2b – 2c boundary. the fine-grained top interval of sub-unit 2c has been dated to 22.035+/-300 a bp, by a sample collected in an excavation just south of melegnano (fig. 2). the architecture of unit 2 can be interpreted on the basis of grain size distribution, stacking patterns, exposed facies associations and gravel composition. its development marks a sudden change of depositional style, that occurs after truncation at the top of the deposits of the meandering fluviatile depositional system of unit 1. sub-units 2a and 2b can be interpreted as the result of sudden invasion of the former alluvial plain by bedload and debris flow – dominated, depositional systems, during at least two different increments of southwards progradation of a distal alluvial fan with braided stream alluvial style. a southward transition to a 370 unit sub unit facies association interpretation 5c vfsl, lcs, p flood plain, oxbow lake (river exposures) gsh, sgt, msp, mst, fsr point bar, transverse bar 5 5a 5b sn, si, fsr, vfsln, ls, lcs, p flood plain, oxbow lake, crevasse (exposures) sg, sgp, sr, lcs, cl, p chute channel, abandoned channel sgn, msgp, sgt, mfsr, lcs point bar 4 (boreholes lcs, fsh, fsr, slm, p flood plain, oxbow lake, crevasse exposures) csn, msp, mst, fsr, fsl, lcs sand bar, point bar, chute channel 3 3b vfsl, lcs, cls, p flood plain, oxbow lake (boreholes rare msgl, msg, sp, st, fsr, lcs point bar, channel fill exposures) 3a (boreholes) cfs, sn, mfs vfs lcs, lc sand bars, flood plain 2c (*) mst, msp, msh, msr, fsl, lc) point bars, abandoned channel fills (°) subsurface (°) ms, vfsl, lcs, l, lc, cl, p flood plain, crevasse splays, soils (*) exposures (°) sg, s, l, lc, p abandoned channel fills (°) csg, cs, ms, fs, fsl sand bars – point bars 2 2b sg, cs, ms, fs, l sand bars, braid plain subsurface g, gs, sg, cs gravel bars 2a fs, fsl, cl, c flood plain, alluvial soils subsurface sg, cs, ms sand/gravel bars, channel fills 1b ms, fs, cl, p abandoned channel fills 1 subsurface csg, cs, fs, cl lateral accretion bars 1a fs, vfs, sl, c, p flood plain, crevasse splays, soils subsurface ms, fs, cl channel fills – point bars tab.2 facies association and interpretation of the five depositional units. codes as in tab. 1 associazione di facies e relativa interpretazione delle 5 unità individuate. codifica come in tab. 1. r. bersezio et al. sandy braid-plain, characterised by channel sequences flanked by flood plain sub-environments, is documented by fringing-out of the gravel units and facies change to a sandy silty succession. a generalised back-step of this depositional system is recorded by sub-unit 2c, which is characterised by sandy facies associations, with abundant fines at the top and within minor sequences. it testifies the transition from a sandy braid plain (north) to a mixed-load depositional style (south), with development of point bars, which is typical of meandering fluvial systems. the fine-grained interval at the top of sub-unit 2c documents the wide diffusion of a flood plain across the entire study area, due either to another back-step of the sand dispersion system, or to an avulsion, capture, or inactivation of the depositional system. compositional uniformity suggests that no major change of the source areas occurred during the different progradation-retrocession steps recorded by unit 2, whose gravels show a mixed north-alpine – south-alpine provenance. 4.2 surface units the upper boundary of units 3, 4 and 5 is the present-day topography. in particular the top of unit 3 forms the largest part of the “livello fondamentale della pianura”, an almost flat surface, sse dipping on average by 1.125‰, which is cut by the terrace scarps of the lambro valley system. the livello fondamentale is run by the meandering traces of the abandoned river network, the most continuous of which are the carpiano – bescapè abandoned stream (west of the lambro valley; bersezio, 1986) and the sillaro meandering trace, to the east (veggiani, 1982; bersezio, 1986). at present these traces are bounded by 1 – 5 m scarps; the average radius of bends is comparable in length with that of the meanders of adda or ticino rivers, i.e. one order of magnitude larger than the present-day and abandoned lambro, olona and seveso river bends. the width of the lambro river valley, sculptured into the livello fondamentale, varies from about 2 km (north) to less than 1.5 km (south; fig. 3). the valley is formed by four orders of minor terraces bounded by different height scarps. the transversal profile of the valley is strongly asymmetrical. three orders of minor terraces are generally observed at the eastern side; they link progressively the elevation of the livello fondamentale with the present day lambro stream, which is lowered by about 15 m. differently, only two terraces are present at the western side, where the difference in height with the livello fondamentale is almost totally achieved by one major scarp, on the right hand of the present-day valley (fig. 3). moreover, the elevation of this western terrace within the valley, is higher than the others on the opposite side, suggesting that no correlation is possible between them. the western and most elevated terrace bounds the top of depositional unit 4; the other minor terraces represent the top surfaces of the different subunits which form the most recent unit 5 (sub-units 5a, 5b and 5c; fig. 3). unit 3 – sandy depositional system unit 3 is the uppermost stratigraphic unit outside the most external terrace scarp which bounds the lambro valley system; it is poorly exposed and crossed by a few boreholes and wells. it includes two sub-units (3a and 3b in ascending stratigraphic order) which develop with a maximum total thickness of about 15 m. sub-unit 3a is bounded at the base by an erosion surface, scoured into the uppermost fine-grained horizon of sub-unit 2c. to the west of the lambro valley subunit 3b is difficult to separate from 3a; differently, to the east of the valley, it forms the uppermost unit between lambro and sillaro, just above sub-unit 3a, or can be deeply scoured into sub-unit 2c (figs. 3, 5 and 6). on the whole sub-unit 3a forms a sandy fining upwards sequence, with discontinuos fine-grained layers and palaeosoils at the top. it is formed by kmsized, coarse to middle sand lenses, dark brown to yellowish in colour, which are locally separated by thin siltmud units (tab. 2). also sub-unit 3b is formed mostly by sand lenses, with a typical yellowish-brown colour and shows a general fining upwards trend, from coarse sand with rare gravel to sandy silt and mud. rare outcrops show the association of graded, gravelly-sands with dm-thick beds of coarse to middle sand with trough cross lamination and low-angle oblique laminasets (tab. 2). these lenses grade upwards to sandy-silt and siltyclay layers, with yellow orange to reddish paleosoils (munsell colours range from 10yr6/8 to 7.5yr5/8 and 2.5y6/6). the meandering palaeo-streams which characterise the top boundary of sub-unit 3b (sillaro and carpiano – bescapè among others) are characterised by the presence of gravel and sand deposits. these abandoned stream traces are cut 1-5 meters below the top of sub-unit 3b, with a top elevation which is in some cases comparable with that of the top of unit 4, which is going to be introduced later on. at present these observations do not seem to be sufficient to correlate these deposits with those of unit 4, but their stratigraphic attribution is still open. therefore we included provisionally these sediments within unit 3, with the specific definition of “unit 3 – abandoned streams” (fig. 3). gravel composition of unit 3 has been obtained mostly for the different sub-units of the group 3b, as far as only a few samples could be collected within unit 3a. as shown in fig.4, the deposition of unit 3 marks an important compositional change, from crystallinedominated to sedimentary-dominated. sedimentary clasts of south-alpine provenance (sandstones, limestones, siltstones, cherts, marlstones, rare conglomerates) are generally more abundant than 43%; sometimes their percentage is as high as 60%. the crystalline rock fragments are on the whole less than 30% (20% metamorphic, 10 % igneous, with the same composition already shown for unit 2). the abundance of the ubiquitous quartz fragments fluctuates between 10 and 20%. fig.4 shows that this sedimentary-dominated composition is also typical of units 4 and 5, with minor differences which can be hardly imputed to provenance variations rather than to hydraulic selection, differential alteration, mixing with recycled clasts from the older units and so on. radiocarbon dating of woody fragments from a peat sample, which was collected at the boundary between sub-units 3a and 3b, at one excavation site close to sordio (fig.2 and 3), allowed the determination of an age of 18.785+/-230 b.p for the top of sub-unit 3a. this date could be calibrated to 20.785 – 19909 cal bc (calib rev4.4.2; stuiver & reimer, 1993). 371aquifer architecture of... additional information is provided by stratigraphic position and cross-cut relations with the other units. subunit 3a is at least older than the quoted radiocarbon age; both sub-units 3a and 3b are cut by the terrace scarp that bounds unit 4, therefore they are older than unit 4 which is the most ancient unit within the lambro valley system. nevertheless, it cannot be excluded that flood deposits coeval with unit 4 veneer the oldest sediments of sub-unit 3b, close to the external margin of the lambro valley. unit 3 can be interpreted as the result of deposition within different palaeo-rivers, with moderate sinuosity and development of longitudinal sand bars (subunit 3a), or highly sinuous, meandering, with development of point bar channel abandonment sequences, with alluvial soils. flood plain fine sediments are locally associated with these depositional elements, and veneer the top of both the sub-units. the gravel composition shows the highest abundance of sedimentary clasts, testifying to provenance from local sources located in the southern alps foothills; the geometry and distribution of sedimentary bodies and of their abandoned traces suggests dispersion of detritus either by multiple streams or by an unstable river with frequent abandonment and avulsions cycles, which could have reached the end-moraines of the lecco brianza area to the north. unit 3 marks the time of definitive disappearance of distal alluvial fan – braided stream depositional systems from the study area, thus documenting the definitive northwards shift of the braided – meandering hinge. it also marks the first appearance of a clearly recognizable network of meandering streams, whose organisation is very close to the present day shape of the fluviatile network. unit 4 – ancient lambro depositional system unit 4 is the most ancient depositional unit of the lambro valley system, within which it is preserved only to the west of the present-day river. it is bounded to the west by the most external terrace scarp, which is less than 2 m in height, and to the east by the internal scarp, which is the highest (on average more than 12 m above the present day flood plain). the top boundary of unit 4 is a terrace surface, whose elevation does not correlate with any other terrace within the valley system, being comparable with the elevation of the sillaro and carpiano – bescapè abandoned streams. the lower boundary is observed locally and is interpreted in the subsurface cross-sections. it is a first order erosion surface cut into sub-unit 2c and 3. unit 4 shows a total maximum thickness of about 12 m. it consists of gravelly-sand and sand facies associations (tab.2), with minor fine grained layers and peat, which form fining upwards sequences. some exposures allow the observation of planar to trough, obliquelaminated sands and gravelly sands, associated upwards with rippled fine sands and mud or peat units. these correspond laterally to thin bedded and fine grained sand with small-scale trough cross-laminae which interbed with laminated silt and peat (tab. 2). some siltmud laminated or massive units contain gastropod and bivalve tests and show some intense burrowing. in the subsurface of the mairano area (fig. 3) borehole correlations allowed the reconstruction of a km-sized sand lens, with minor fine-grained layers at the top (fig. 5 and 6, section 11), which is truncated by a terrace scarp to the east. gravel composition of unit 4 is comparable to that of sub-unit 3b, and very close to that of sub-unit 3a (fig. 4): sedimentary lithoclasts are largely more abundant than crystalline rock fragments, which are often moderately to deeply weathered. no direct age determinations are available for unit 4. stratigraphic relationships indicate that it should be at least younger than 20.785 – 19909 cal bc, but this is only an approximation of its maximum age, as the timespan represented by sub-unit 3b could not be estimated yet. in any case unit 4 is cross-cut by the erosional lower boundary of sub-unit 5a. geometry of sedimentary bodies and facies association of unit 4 allow the interpretation of its fining upward sequence as the result of lateral accretion and sse migration of a channel point bar system, typical of a mixed load, meandering fluvial style. this is quite obviously confirmed by the relationships with the geomorphological features of the surface boundaries of this unit. unit 4 represents the oldest deposits of the lambro valley meandering system. as it has been previously stated, a time correlation with the sediments deposited into the meandering abandoned streams which are cut into the livello fondamentale outside the lambro terrace scarps, cannot be excluded. local provenance of sediments is documented by prevalence of sedimentary clasts within the gravel-sized facies; obvious mixing with second cycle clasts, eroded from the older alluvial succession and/or from the glacial deposits of the northern end-moraines, is witnessed by the presence of weathered crystalline clasts, which originated in the internal alps. unit 5 – post glacial lambro depositional system unit 5 is formed by the sediments which were deposited within the lambro valley system during its progressive entrenchment, to form three orders of terraced units, which are progressively lowered to the present day elevation of the lambro stream (about 15 m below the livello fondamentale). these terraces bound the top of three sub-units, 2 6 m thick, whose lower boundaries merge to form the 1st order surface that delimitates the lambro:valley system. as a rule this surface is marked by gravel lags or by a very typical concentration of mud clasts, sometimes as large as 80 cm. sub-unit 5a is preserved only on the eastern side of the present-day lambro; it is bounded by an erosion surface at the base, which truncates laterally and vertically unit 4, 3 and sub-unit 2c. sub-unit 5b, whose base truncates also sub-unit 5a (fig. 7), is preserved on both sides of the river at an intermediate elevation. sub-unit 5c is the present-day channel-bars-floodplains system of the lambro river. sub-units 5a and 5b are formed mostly by sands and gravels which are organised in flat lenses, tens to hundreds of meters in size, up to 6 m in height, with lateral accretion of fining upwards gravel-sand units (fig. 8a). the typical facies association of these lateral accreted lenses (tab. 2) includes a lower graded gravel bed, soled by a flat erosion surface and covered by coarse – middle, trough to planar, cross-laminated sand, which are followed by ripple cross-laminated fine sand and laminated to massive muddy silt. sometimes, 372 r. bersezio et al. sediments of unit 5. among the gravel fraction of subunit 5b, brick fragments and other artefacts are recurrent. these fragments are imbricated with the other clasts, documenting that they were caught-up by fluvial transport. age determination of unit 5 is based on several different evidences. the base of sub-unit 5a cross-cuts units 3 and 4, therefore it is at least younger than 20.785 – 19909 cal bc. the brick fragments that we found within 5b point bars indicate an historical age for sub-unit 5b. based on the typology of the recovered artefacts (cremaschi, pers. comm., 2003) a time span between the roman age and the renaissance has been recognised. sub-unit 5c is the recent – present-day depositional unit. based on this evidence we suggest 373 fig.7 gravel point bar (sub-unit 5a) laying over truncated , well-sorted grey sands of sub-unit 2c. lambro valley, outcrop o19 (fig. 3). barra di meandro a granulometria ghiaioso – sabbiosa (subunità 5a), ricoprente le sabbie grigie, ben selezionate della sub-unità 2c. affioramento o19 nella valle del lambro (ubicazione in fig. 3). fig.8 a) sub-unit 5b (domodossola, outcrop o19 of fig. 3; see also line-drawing in the lower insert of the same picture). lateral accretion of a sandy-gravelly point bar; note the flat surface at the top, covered by differently oriented sand mesoforms. total height is about 5 m (hammer on the left for scale). b) same location of picture (a): sub-unit 5b, historical point bar cut by chute channel; note the gravel lag and bar filling the chute channel, with an upwards fining sequence. spillover and flood plain fine grained deposits seal the bar-chute sequence. a) sub-unità 5b (domodossola, affioramento =19, fig. 3; confrontare con lo schizzo di fig.3). accrezione laterale di una barra di meandro sabbioso-ghiaiosa, delimitata a tetto da una superficie planare, coperta da mesoforme di fondo sabbiose a differente orientazione (altezza totale dello spaccato, circa 5 m; martello di scala sulla sinistra). b) stessa ubicazione di (a): subunità 5b, barra di meandro di età storica, troncata da canale di rotta con riempimento di ghiaie residuali e barre ghiaioso-sabbiose in sequenza fining-upwards. la successione è sigillata da sedimenti fini di esondazione. metres-thick, silty-clay and clay plugs are preserved at the top of the ε-cross stratified units. more frequently the same are cut by rounded scours, which are filled either by gravel-sand lags and bars, or plugged by sandy clay and peat (tab. 2; fig. 3; fig. 8b). the lateral accreted lenses are laterally juxtaposed and vertically superimposed on one another, by means of almost flat erosion surfaces (fig. 8a). recurrently they are separated by metres-thick fine grained units, formed by the association of laminated to massive silty-mud, with thin sand beds which can be graded, horizontal laminated or rippled (tab. 2). sub-unit 5c is represented by the present-day sediments of the lambro river, which are actively evolving. they include gravel-sand units, forming tens of meters long, 1 – 3 m high point bars, side bars, middle channel bars. gravel material is mostly recycled from the older units, as well as for the abundant mud clasts, which slide into the channel from the erosional shores. the present-day narrow flood plain is covered by rippled fine sand and silt to mud layers. some silty mud layers (spill-over deposits) are observed outside the “normal” flood plain (which is constrained within the terrace scarp between sub-unit 5b and 5c); these veneers are deposited above the terraces of sub-unit 5b and locally also above the terrace of unit 4, marking the highest levels reached by the exceptional floods (one of which occurred during the fall of 2000) in the narrowest sectors of the valley system. gravel composition of unit 5 is homogeneous and very similar to that of unit 4. sedimentary clasts are the most abundant (on average more than 50%); metamorphic (20% on average) and igneous (mostly granitoids; 10%) are subordinate; quartz fragments of different origin are, as usual, as abundant as about 20% of the total. most of crystalline fragments are variably weathered; differently the sedimentary clasts show very low to absent alteration. some peculiar lithologies, which occurred with very low abundances in the sediments of unit 3 (intermediate to acidic porhyrites and rhyiolites) or of unit 2 (green metabasites and serpentinites), are no longer observed within the gravel-size aquifer architecture of... that unit 5 represents the post-glacial (holocene) deposits of the lambro valley system. the interpretation of the depositional elements which form sub-units 5a and b is based on their facies assemblage, geometry, surface morphology and relationships with the shape and fluvial style of the lambro valley system. the lateral accreted units are directly recognised as point-bar deposits, with a partially preserved shape. chute channels are cut into these pointbars. they are filled by gravelly-sand bars and silt-clay plugs. the fine grained sediment facies associations with sand lenses (tab. 2) are interpreted as typical flood-plain crevasse splay deposits. finally, the sandmud lens-shaped units, with peat, are recognised as typical channel abandonment sequences, with deposition within oxbow lakes. these interpretations are confirmed by the depositional processes and facies which have been described for the present-day sub-unit 5c. gravel petrography supports the interpretation of local provenance of detritus, both from the oldest alluvial and glacial sediments, and from the mesozoic rocks which are at present under erosion in the south-alpine foothills of the brianza, which are the source areas of the holocene lambro river. 5 discussion 5.1 stratigraphy the five informal units defined above can be compared to the stratigraphic framework of the po plain quaternary succession, both based on physical stratigraphy and on time equivalences. for clarity they will be re-examined in descending stratigraphic order, from the youngest unit 5 to the oldest unit 1. unit 5 represents the most recent depositional unit, confined within the lambro valley system, which formed during its recent entrenchment below the livello fondamentale. based on stratigraphic relationships, age determinations and fluvial style, it can be attributed to a post-glacial, holocene age. therefore, it is equivalent to the post glacial unit of the northern sectors of the po plain (bini et al., in press). the correlation with regional stratigraphy of unit 4 is affected by some incertitude. it is confined within the lambro valley system, and its age is constrained by the minimum age of unit 3a (20.785 – 19909 cal bc) and the maximum age of unit 5b (historical). it could therefore be attributed both to the latest pleistocene and to the holocene. in the latter case it should be included into the post glacial unit together with unit 5. unit 3 represents the depositional systems which build the morphological surface of the livello fondamentale, outside the terraces of the lambro valley system. it is constrained in age by the youngest age available for sub-unit 2c (22.035+/-300 a bp ) and the age of the boundary between sub-units 3a and 3b (20.785 – 19909 cal bc). in addition to these data, the stratigraphic position, gravel composition and depositional style suggest a correlation with the alluvial units which were deposited during the waning time of l.g.m. (crowley & north, 1991; bini et al., in press). in this case we could suggest a correlation with the deposits of the alloformazione di cantù, which have been recognised within the entrenched valleys to the north of the study area by strini (2001). as no physical correlation is available yet between the two areas, we consider this interpretation as a working hypothesis for ongoing studies. unit 2 represents the coarsest grained unit of the lambro area; the composition of its gravels is dominated by alpine-sourced clasts, with a strong fingerprint of provenance from the metamorphic basements of southern and northern alps. the age of the uppermost sub-unit 2c is constrained within 24.620+/-160 a bp and 22.035+/-300 a bp, but no constraints are available for the lowermost sub-unit 2a. these data indicate a minimum late pleistocene age for unit 2. in addition we can also consider that, based on regional dip of stratigraphic units, unit 2 should be at the surface to the north of the study area. in this area, a sand-gravel unit with a comparable gravel composition, represents the shallowest stratigraphic unit, bounded by the topographic surface. by physical correlations, strini (2001) was able to include this unit into the besnate allogroup (da rold, 1990; bini, 1997a; b). this allogroup is formed by several glacial, glacio-fluvial and alluvial units, which form at least 5 alloformations related to different glaciations (bini, 1997a). therefore we suggest that the three sub-units which form unit 2 can be correlated with the besnate allogroup of the pedealpine area. however, we cannot exclude alternative correlations for sub-unit 2a, which could also represent a glacio-fluvial succession , correlative to a pre-besnate glaciation. the stratigraphic correlation of unit 1 is highly uncertain, because we have neither physical correlations, nor age determinations. unit 1 has been deeply eroded by the lower boundary of unit 2, and is characterised by a mostly fine-grained facies association, that we interpreted as a distal, meandering fluvial succession. this advises against interpreting this unit as a glacio-fluvial succession linked to a pre-besnate glacial advance. actually, in the most conservative hypothesis, it could represent an ancient post-glacial unit, of prebesnate age; otherwise it could also represent a preglacial unit. this second hypothesis would imply an age older than middle pleistocene (penk & bruckner, 1909; kukla & cilek, 1996), which is not supported, at present, by any circumstantial evidence. 5.2 sedimentary evolution the lambro area is a part of the alluvial plain which developed during middle – late pleistocene between the south-alpine and apenninic thrust fronts. the depositional style of filling of this former pliocene – early pleistocene marine area has been controlled principally by northwards propagation of the apennine frontal thrusts (salerano and san colombano ramp anticlines; pieri & groppi, 1981; bersezio et al., 2001; fantoni et al. 2003, with references therein), uplift on the alpine side (arca & beretta, 1985), onset and dynamics of glaciations (since the middle pleistocene; penk & bruckner, 1909; bini, 1997a with references therein), dynamic of the regional base-level and erosion-deposition hinge. the succession that we could investigate developed in an alluvial environment, built by the coalescent deltas of transversal alpine rivers and palaeo-po axial system, when the coast-line was already far away, to 374 r. bersezio et al. the east of the study site (dondi & d’andrea, 1986, regione lombardia – eni, 2002). in fact no indications of marine influence has been found in the deepest succession that we studied (unit 1). this succession resulted from two steps of se-wards migration of a meandering river depositional system (tab. 2), which are separated by an avulsion or a marked retrogression step, documented by the widespread diffusion of flood-plain and palustrine fine-grained sediments. whether this was due to tectonic control by uplift increments of the salerano – san colombano anticlines (“forced regression” concept of regione lombardia – eni, 2002) or to the response to glacial pulses of a pre-besnate glaciation, or to a combination of the two, cannot be stated with the presently available data. a subsequent, late pleistocene, north-westwards shift of the erosion-deposition hinge, is witnessed by the development of the deep erosion surface that soles unit 2, at the onset of the besnate glaciations (bini, 1997a, b). the kriged, plan and 3d view of this surface is portrayed in fig. 9 (lower maps). this unit documents two major south-eastwards progradation increments of distal, braided alluvial fans, fed from southand northalpine sources. during both steps, the transition to a southern fluvial plain is recorded in the centre of the studied area. the position of the south-eastern fan boundary is clearly recognised in fig.9, by a marked downward step of the 2a – 1b boundary, together with the channel like shape of the same erosion surface more south-eastwards. the mildly erosional base of sub-unit 2c, which mimics the original shape of the top of the alluvial fan sub-unit 2b, is shown in the same picture, that allows the appreciation of the marked southeastwards shift of the southern fan boundary, fringing to a fluvial plain system. a direct control from the major late pleistocene glaciations can be suggested for these dynamics, linking basal erosion and subsequent progradation of the three coarse-grained depositional systems with the onset and evolution of a glacial stage of the besnate. the fine-grained deposits of the retrogression stage at the top of unit 2a was poorly developed or incompletely preserved. differently sub-unit 2c, which is dated between the non-calibrated dates of 22.000 and 24.000 a bp, documents almost entirely the latest cycle of the besnate, with a widely preserved fine-grained fluvial unit at the top. a new regional erosion surface heralds the southwards migration of the sandy braid-plain meandering river depositional system (unit 3) that developed during the l.g.m. glaciation. the time bracket that is identified by radiocarbon dates (22.000 – 19.900 a bp) for deposition of sub-unit 3a, allows for correlation with the isotope stage 2 (martinson et al., 1987). this is in good agreement with the gravel-sand depositional style of this unit, which differs from the overlaying meandering systems of sub-unit 3b, that could correlate with a glacial retreat. at this time the entire study area was located south of the braid-plain/meandering hinge, as it is portrayed by the map of the lower boundary of subunit 3b (fig. 9), which shows several entrenched and sinuous scours, cross-cutting to one another. the post-glacial evolution is recorded by the entrenched meandering depositional systems of the lambro valley system (units 4 and 5). their deepening was very fast, and high erosion rates lasted up to historical times, if we consider that the top of the “renaissance age” l.s. point bars of sub-unit 5b is about 6 m above the top of the present-day bars of the lambro river. this is related to the dynamics of the local baselevel (po river), and could be triggered by the ongoing slow uplift of the apennine structures. 5.3 hydrostratigraphy and bearings on hydrogeologic modelling the previous reconstruction of stratigraphic architecture provides the base for the definition of aquifer stratigraphy of the lambro area, valid for a thickness of about 100 m. this can be visualised with the aid of the cross-sections in figs. 5-6 and of the plan view of the kriged boundaries of the most relevant units (fig. 9). the distribution and connectivity of the gravel – sand intervals vs. thickness, complexity and continuity of the fine-grained units, defines the aquifer organisation of this succession. taking into account the basic definition of hydrostratigraphic units (maxey, 1964; anderson, 1997 with references therein) it is possible to identify three aquifer units (in ascending order: lower sub-unit 1a; sub-units 1b-2a-2b-lower 2c; units 3-45), which are discontinuously separated by two aquitards (upper sub-unit 1a; upper sub-unit 2c). the separation between aquifers is very poor in the northern sector of the study area, where the sand: gravel units merge due to erosion and/or non-deposition of the fine grained layers at their base (fig. 5 and fig. 6). we do not propose any label for these hydrostratigraphic units, because aquifer classification is already sufficiently confused in literature (martinis & mazzarella, 1971; avanzini et al.,1995; francani, 2001; regione lombardia – eni, 2002). we shall refer to them respectively as “lowermost”, “intermediate” and “uppermost” aquifer, being aware of their local significance, which is restricted to the study area. the lowermost aquifer is mostly sandy and shows internal complexity, due to southwards fringing of the sand-bodies, which alternate with silt-mud, flood plain intervals. the aquitard at its top is represented by the widespread flood plain muddy unit that tops the finingupwards sequence 1b. although it is locally truncated northwards (fig. 9, maps of base 2a), it seems to represent an efficient confining layer at the scale of the study area. the intermediate aquifer is the coarsest and thickest one. it corresponds to the lower part of the “aquifero tradizionale” (auct.), and possibly could belong to aquifer group a (?) of regione lombardia – eni (2002). it is formed by gravel-sand bodies, which are interconnected to the north due to the development of the regional erosion surface that soles unit 2 and of the sharp progradation surface of sub-unit 2b above 2a. southwards these coarse-grained bodies fringe out, due to transition from braided alluvial style, to meandering fluvial deposition, with development of flood plainoxbow lake-channel abandonment fine-grained deposits. seemingly, the retrogradation of the 2b gravel-sand body determined the development of a general upwards fining succession, whose sand – mud alternations form the overlaying complex aquitard. the efficiency of the latter is strongly affected by erosion of sub-unit 2c to the north and east (figs. 5, 6 and 9), that determines the connection with the uppermost aquifer, and locally with the topographic surface (lambro valley system, 375aquifer architecture of... 376 f ig .9 k ri g e d i so b a th s (r ig h t) a n d 3 d v ie w ( le ft ) o f th e l o w e r b o u n d a ri e s o f su b -u n it s 2 a , 2 c , 3 a n d o f th e p re se n td a y to p o g ra p h y. a t th e e xt re m e r ig h t, t h e i so p a c h m a p s o f su b -u n it s 2 a -b a n d 2 c a re r e p re se n te d . t h e m a p s sh o w t h e b a sa l sc o u ri n g o f th e a q u ife r u n it s in to t h e f in e -g ra in e d a q u it a rd s, c u m u la ti ve t h ic kn e ss o f th e m o st i m p o rt a n t a q u ife r (s u b -u n it s 2 a a n d b ) a n d th e p o st -g la c ia l e n tr e n c h m e n t o f th e l a m b ro v a lle y sy st e m . m ap p e d e lle is o b at e e v is io n e 3 d d e i l im it i i n fe ri o ri d e lle s u b -u n it à 2 a , 2 c e 3 ; in a lt o è r ip o rt at a la r ic o st ru zi o n e d e lla t o p o g ra fia . l e m ap p e s o n o o tt e n u te p e r kr ig in g d e lle s u p e rf ic i i n d ic at e . a d e st ra s o n o r ap p re se n ta te l e m ap p e d i is o p ac h e d e lle s u b -u n it à 2 a -2 b e 2 c . l e m ap p e i llu st ra n o l ’e ro si o n e a lla b as e d e g li ac q u ife ri p ri n c ip al i, ap p ro fo n d it i al l’i n te rn o d e i re la ti vi a c q u it ar d i, lo sp e ss o re d e ll’ ac q u ife ro in te rm e d io ( 2 a b ) e l’ ap p ro fo n d im e n to p o st -g la c ia le d e l s is te m a va lli vo d e l l am b ro . r. bersezio et al. fig. 9 uppermost map). therefore, the intermediate aquifer is a multi-pay, partly confined aquifer unit, whose separation from the surface waters is not completely ensured throughout the study area. however, its bulk recharge should be looked for also northwards of the same area, where the top of the besnate allogroup is close to the surface (strini, 2001). the uppermost aquifer is the phreatic one and includes the non-saturated zone at its top. the recent regional piezometric maps (francani, 2001) indicate that the water table-top fluctuates between 5 and 10 m below the topographic surface. field observations of excavations, quarries, borehole drillings and terrace scarps, indicate that temporary and local water nappes are contained at least up to a depth of 2 m below the surface. this is confirmed by semi-permanent historical water sources which are aligned on the scarps of the major terrace of the lambro river. these ground waters are only intermittently and locally in contact with the lambro river waters. these observations are clearly justified by the organisation in minor fining upwards sequences of sub-unit 3b, with flood plain fines which act to compartment ground waters within the phreatic nappe. below the upper part of this unit, there is a good potential interconnection among the gravel-sand lenses of units 3a and 4, as far as they are juxtaposed by deep erosion surfaces. this observation holds also for the relations with the intermediate aquifer, which is truncated at the top by the lower erosional boundary of the lambro valley system (fig. 6). in fact the uppermost aquifer is deeply dissected by the lambro terrace scarps (fig. 9, left). the top of the uppermost aquifer is only poorly protected by sandy soils (brenna, 2002), therefore this unit acts like a vertical filtration zone recharging this shallow aquifer and contributing to the recharge of the intermediate one. 6 conclusions aquifer stratigraphy and architecture of the upper pleistocene succession of the lambro valley area, south of milan, has been built by the dynamics of alpine-fed, alluvial depositional systems. the hydrostratigraphic complexity is determined by: • the late pleistocene, glacial controlled, erosion progradation – retrogression cycles, that determined the repetitive stacking of gravel/sand, fining upwards sequences (most permeable aquifers), topped by widespread, fine-grained, least permeable units (aquitards); • the erosional entrenchment of depositional systems, controlled by the dynamics of the erosion – aggradation hinge under the influence of climatic cycles and local uplift of the salerano – san colombano ramp anticlines, that shaped the connectivity of the most permeable bodies; • the nw – se transition from distal alluvial fan/braid plain to meandering fluvial/flood plain depositional systems, that occurs in the centre of the studied area. the lowermost aquifer (sub-unit 1a) is a multi-pay, confined unit, presumably developed during an interglacial period of pre-besnate age. it is partly sealed by alluvial plain fines (top of 1a). the intermediate aquifer (sub-units 1b, 2a, 2b, lower 2c) corresponds to the traditional aquifer auct. and to part of aquifer group a (regione lombardia – eni, 2002), and includes a pre-besnate sand – gravel unit and the alluvial depositional systems equivalent to the besnate. it is a multi-pay unit, formed by stacked cycles of advancement and retreat of distal alluvial fan/braid plain, only partly confined at the top by the retrogradational fines of the upper part of sub-unit 2c. it is recharged in the area of northern emergence of the besnate allogroup and locally by the surface waters, including the strongly compromised lambro river waters. the uppermost aquifer includes the phreatic/non saturated zone and is formed by the braid-plain to meandering depositional system (unit 3) which correlates with the l.g.m. in the study area; it is in full contact with the post glacial to historical meandering depositional system of the lambro valley (units 4 and 5). it is only poorly protected by discontinuous flood plain fines and by mostly sandy surface soils. acknowledgements this work was 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(eds.), note illustrative della carta geomorfologica della pianura padana. suppl. geogr. fis. dinam. quat., iv, pp. 55-68. veggiani a. (1982) variazioni climatiche e dissesti idrogeologici dell’alto medioevo in lombardia e la rifondazione di lodi sibrium, 16, pp. 199 – 208, lodi. 378 ms. ricevuto l’11 maggio 2004 testo definitivo ricevuto il 16 novembre 2004 ms. received: may 11, 2004 final text received: november 16, 2004. r. bersezio et al. microsoft word 10_rovere_lm05.doc available online http:/amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 25 (2), 2012, iii-v medflood project: mediterranean sea-level change and projection for future flooding alessio rovere1, stefano furlani2, jonathan benjamin3,4, alessandro fontana5, fabrizio antonioli6 1 lamont doherty earth observatory, columbia university, ny 2 university of trieste, it 3 university of edinburgh, uk 4 wessex archaeology coastal & marine uk 5 university of padova, it 6 enea, rome, it corresponding author: a. rovere <rovere@ldeo.columbia.edu> abstract: medflood is a four-year interdisciplinary project recently launched by a team of scientists working in fields concerned with mediterranean sea-level change. the project has the timely and ambitious aim to build a spatially explicit database of relative sea levels for the mediterranean and to use this resource to model risk and help project future flooding in and around the mediterranean basin. keywords: relative sea-level change, mediterranean flooding, sea-level index points, past and future sea levels. 1. introduction it is widely recognized that reconstruction of holocene relative sea levels (rsls) is of fundamental importance for understanding glacio-isostatic adjustment (gia) (and fine-tuning gia models) as well as to assess coastal vulnerability to sea-level rise (cf. antonioli et al., 2009). moreover, holocene rsl data provide information on vertical land movements, even at the local scale, caused by tectonic and/or volcanic structures. in addition to the ‘eustatic’ values provided by the ipcc (lambeck et al., 2011), these are important components of future sea-level projections. the mediterranean sea, with its small tidal ranges and relatively low-energy storms (which favour the preservation of sea-level markers along coastlines) has been the theatre of several studies related to fieldmeasures of past sea levels using rsl markers for over four decades (cf. kershaw and guo, 2001; pirazzoli, 2005). antonioli et al. (2009) reviewed sea-level markers along the italian and istrian (western slovenian and northwest croatian) coastlines, and counted 127 studies containing different rsl markers. other areas where a significant focus on the topic has resulted in a number of studies related to holocene rsl markers carried out include greece, spain and france. the southern part of the basin is characterized by coastal zones where data are lacking or published locally, and are therefore not widely available. in the mediterranean, different types of source data have been used to reconstruct rsls including biological markers (cf. laborel and laborel-deguen, 1994), sedimentological (cf. dubar and anthony, 1995), geomorphological (pirazzoli, 1996) and archaeological (cf. auriemma and solinas, 2009; see also galili and rosen, 2011 for early holocene data from the eastern mediterranean). much greater amounts of published data exists and such literature, still rapidly growing, has led to the obvious consequence of fragmented information. as such, data are only occasionally reviewed with reference to specific location, but not as a whole, since there has never been a concerted effort to compile this into an organic, yet central database which could then be analysed on a truly ‘mediterranean scale’. 2. aims and objectives the main aim of the medflood project, sponsored by inqua for 2012 and of anticipated duration of four years (2012-2015), is to create a comprehensive, coherent, spatially explicit and updatable database containing holocene and mis 5.5 rsl data available in literature for the mediterranean basin. the database, coupled with considerations on vertical land movements due to tectonics, volcanic and isostatic effects, will create an enhanced platform for evidence-supported projections of future sea level which can in turn be used to supplement coastal-flooding models and maps. the database will be freely accessible and downloadable. three subordinate objectives have been identified: 1. conduct a review of observational rsl evidence across the mediterranean for mis 5.5 (132-116 ka) and post-lgm (18 ka) and compare known field data with model predictions (lambeck et al., 2011) coupling them with the evaluation of tectonic and volcanic contributions to the displacement of mis 5.5 markers. 2. produce a web-gis containing mis 5.5 and holocene shorelines, freely accessible by users and fed by input data provided by registered users. rovere a. et al. iv f ig . 1 p o st -l g m ( fr o m t h e a d d iti o n a l m a te ri a l in l a m b e ck e t a l., 2 0 1 1 ) a n d l a st i n te rg la ci a l (m is 5 .5 ) (f ro m t h e a d d iti o n a l m a te ri a l in p e d o ja e t a l., 2 0 1 1 a n d f e rr a n ti e t a l., 2 0 0 6 ) r s l d a ta p u b lis h e d i n r e vi e w p a p e rs f o r th e m e d ite rr a n e a n . m e d f l o o d a im s to o rg a n iz e u n d e r a s in g le s tr u ct u re a n d e xp a n d t h e se d a ta se ts . t o p o g ra p h y fr o m s r t m d a ta ( h tt p :/ /w w w 2 .jp l.n a sa . g o v/ sr tm /m is si o n .h tm ). medflood   v 3. obtain future sea-level projections and create model flood maps based on the available digital terrain models and on ipcc sea-level scenarios, taking into account isostatic and tectonic effects. 3. actions medflood was originally designed with the participation of 15 international scientists, experts in different regions of the mediterranean, or in different fields of study concerned with rsl, including gia modelling, archaeology, geology or geomorphology, sedimentology and gis mapping. four project leaders, who will follow the advancement of the project through its duration, lead this group. to achieve its goals, actions will be initiated by medflood, which can be divided into the following categories. networking and dissemination tools this action is focused at establishing a network of scientists (“the medflood team”), coordinated by the four project leaders, who will submit data and cooperate towards the achievement of the project objectives. the team will be updated on the project advancement with a mailing list, and via the website of the project, www.med flood.org. each year, a workshop will be organised, open to scientists working in a relevant field and willing to participate. here, ideas and new approaches to the issues of rsl mapping and future sea-level rise projection will be discussed, with particular emphasis on practical solutions to be implemented for medflood’s success. crowdsourcing and web-gis construction the core idea of medflood is that the most efficient solution to build large databases is represented by ‘crowdsourcing’ (a word introduced in 2006 by j. howe in wired magazine, [whitla, 2009] to describe the process of outsourcing an activity to an undefined (and generally large) network of people in the form of an open call. with this idea, a common structure for submitting rsl data will be established. this will include, but will not be limited to: the type of marker, its elevation and its significance in indicating past sea-level position, and other information relevant for the correct interpretation of the marker (such as tectonic activity in the area). the medflood team (and scientists requesting access) will be asked to fill a web form with this information, in order to obtain a standardized database. the results will be checked for completeness and to avoid duplicate records, and will then be updated into a web gis. from here, a user will be able to query and download the data and to see their spatial representation. future flooding scenarios this action is aimed at defining future flooding scenarios, combining corrections for gia effects across the mediterranean, tectonic uplift/subsidence estimates from the rsl database, and sea-level rise scenarios from ipcc. digital elevation models will be sourced and purchased in the second year of project from national cartographic institutes across the mediterranean, and flooding risk maps will be produced using geospatial statistical analyses. flooding maps will be obtained using the methodology described in lambeck et al. (2011), based on the combined observational-computational solutions. 4. anticipated scientific results the various experts within the medflood team will interact and share field observations for geology and archaeology and modellers of past glacial changes. this will allow us to provide constraints on past sea levels and, where possible, on estimated future sea-level rise. the key achievements of the projects will be: ٠ improved knowledge of mis 5.5 and holocene shorelines along the coasts of the mediterranean; ٠ updated glacial-isostatic modelling for the mediterranean; ٠ enhanced understanding of vertical land movements in the mediterranean; ٠ the creation of a freely accessible web-gis with mis 5.5 and holocene shoreline data; ٠ the creation of regional sea-level rise projections for 2100 using the available dtms; ٠ collaboration with ipcc for the mediterranean sea; ٠ publication of results in international, peer-reviewed scientific journals and online; ٠ dissemination of results to policy makers and managers for planning, land use and hazards related to future sea-level rise. references antonioli f., ferranti l., fontana a., amorosi a., bondesan a., braitenberg c., dutton a., fontolan g., furlani s., lambeck k., mastronuzzi g., monaco c., spada g., stocchi, p. (2009) holocene relative sea-level changes and vertical movements along the italian and istrian coastlines. quaternary international, 206, 102-133. auriemma r., solinas e. (2009) archaeological remains as sea level change markers: a review. quaternary international, 206, 134-146. dubar m., anthony e.j. (1995) holocene environmental change and river-mouth sedimentation in the baie des anges, french riviera. quaternary research, 43, 329-343. ferranti, l., antonioli, f., mauz, b., amorosi, a., dai pra, g., mastronuzzi, g., monaco, c., orrù, p., pappalardo, m., radtke, u., renda, p., romano, p., sansò, p., verrubbi, v., 2006. markers of the last interglacial sea-level high stand along the coast of italy: tectonic implications. quaternary international 145-146, 30-54.galili e, rosen b. (2011) submerged neolithic settlements off the carmel coast, israel: cultural and environmental insights. in: benjamin j., bonsall c., pickard c., fischer a. (eds), submerged prehistory. oxbow, oxford, pp. 272-286. kershaw s., guo l. (2001) marine notches in coastal cliffs: indicators of relative sea-level change, perachora peninsula, central greece. marine geology, 179, 213-228. rovere a. et al. vi laborel j., laborel-deguen f. (1994) biological indicators of relative sea-level variations and of co seismic displacements in the mediterranean region. journal of coastal research, 10, 395-415. lambeck k., antonioli f., anzidei m., ferranti l., leoni g., scicchitano g., silenzi s. (2011) sea level change along the italian coast during the holocene and projections for the future. quaternary international, 232, 250-257. pedoja, k., husson, l., regard, v., cobbold, p.r., ostanciaux, e., johnson, m.e., kershaw, s., saillard, m., martinod, j., furgerot, l., weill, p., delcaillau, b., 2011. relative sea-level fall since the last interglacial stage: are coasts uplifting worldwide? earth-science reviews 108, 1-15. pirazzoli p.a. (1996) sea-level changes: the last 20,000 years. wiley & sons, new york, us. pirazzoli p.a. (2005) a review of possible eustatic, isostatic and tectonic contributions in eight lateholocene relative sea-level histories from the mediterranean area. quaternary science reviews, 24, 1989-2001. whitla p. (2009) crowdsourcing and its application in marketing activities. contemporary management research, 5, 15-28. ms. received: may 2, 2012 final text received: jun 10, 2012 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /all /binding /left /calgrayprofile (gray gamma 2.2) /calrgbprofile (srgb iec61966-2.1) /calcmykprofile (u.s. web coated \050swop\051 v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.4 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings true /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 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documenti pdf creati possono essere aperti con acrobat e adobe reader 5.0 e versioni successive.) /enu (use these settings to create adobe pdf documents suitable for reliable viewing and printing of business documents. created pdf documents can be opened with acrobat and adobe reader 5.0 and later.) >> >> setdistillerparams << /hwresolution [1200 1200] /pagesize [396.850 566.929] >> setpagedevice imp.moretti& effetti dei “miglioramenti fondiari” nelle murge alte (puglia): l'impatto antropico sul paesaggio carsico e costiero massimo moretti1, antonio fiore2, piero pieri1, marcello tropeano3 & salvatore valletta2 1dipartimento di geologia e geofisica, università degli studi di bari – m.morettii@geo.uniba.it 2sigea sezione puglia, bari puglia@sigea.org 3dipartimento di scienze geologiche, università della basilicata, potenza tropeano@unibas.it riassunto: moretti m. et al., effetti dei “miglioramenti fondiari” nelle murge alte (puglia): l’impatto antropico sul paesaggio carsico e costiero. (it issn 0394-3356, 2004). l'area delle murge rappresenta un territorio carsico ricco di zone d'interesse ambientale e nella quale sono in corso di istituzione due importanti parchi (parco nazionale dell’alta murgia e parco regionale delle gravine). negli ultimi decenni esso è stato soggetto a profondi mutamenti legati all'azione antropica. fra questi viene qui analizzato quello legato all'introduzione di particolari operazioni di "miglioramento fondiario". tali operazioni, definite genericamente come "spietramento", consistono nello scarificare e triturare meccanicamente la porzione sommitale del substrato roccioso calcareo in aree dove i suoli sono assenti o caratterizzati da spessori modesti. mediante tali operazioni si riesce quindi ad ottenere in superficie un sufficiente spessore di suolo dotato di scarsa coesione che permette la messa a coltura di aree caratterizzate da una bassa vocazione agricola e tradizionalmente adibite a pascolo. il presente lavoro è incentrato sullo studio degli effetti di queste pratiche sistematorie sull’ambiente carsico e costiero delle murge. abstract: moretti m. et al., the effects of “soil improvement” operations in the murge alte area (southern italy): the impact on the karstic and coastal landscape. (it issn 0394-3356, 2004). the murge area (puglia, southern italy) is a morpho-structural high which is located in the intermediate sector of the emerged apulian foreland. the higher part of the murge area (murge alte sector) is characterized both by the absence of post-cretaceous marine deposits and by a mature karstic landscape. the soils in the murge alte region are the result of a series of complex pedogenetic processes that started on the residual products of cretaceous limestones. these soils tendentially have a clayey granulometric composition with an high content in fragments and blocks of limestones: often they are shallow, less than 20 cm, originating from the emerging calcareous rocks. historically, in this area, the presence of thin soils and the scarsity of water prevented a massive development of agricultural activities and, typicallly it was mainly a grazing land. nevertheless, recently (last 20 years) the action of public financing (mainly ue founds) has promoted the introduction of soil improvement operations. these operations are characterised by massive ploughing and crushing of the carbonate bedrock and have induced some important effects both in the karstic landscape and in the hydrogeological balance. this paper is focused on the analysis of these effects both in the higher and coastal zones of the murge area. in particular, in a very short period of time (only 20 years), the analysed soil improvement operations have produced the following irremediable effects: the breaking up of the soil-rocky substratum complex; alteration of the granulometric range size of the soil (massive increase in finer particles); increase in soil loss; alteration of the superficial and deep karstic system; increase in flood risk. parole chiave: impatto antropico, uso del suolo, aree carsiche e costiere, murge, italia meridionale. keywords: human impact, land use, coastal and karstic area, murge, southern italy. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 323-330 1. introduzione l'altopiano carsico delle murge alte nord-occidentali (fig. 1) è stato inserito come "area di reperimento" nella l. 394/91 (legge quadro sulle aree protette) e proposto per l'istituzione quale parco nazionale dell'alta murgia con la conferenza dei servizi promossa dalla regione puglia nel novembre 1993. comunque, tutta l'area perimetrata dal parco nazionale dell'alta murgia è già sottoposta a vincolo idrogeologico ed è zona di tutela del piano regionale risanamento della acque (p.r.a.), oltre che già ricompresa nel proposto sito di importanza comunitaria (psic) nonchè zona di protezione speciale (zps) “murgia alta”. nella stessa area sono presenti numerosi elementi d'interesse storico (fra tutti si cita castel del monte) mentre, sotto il profilo paesaggistico, gli aspetti geomorfologici connessi al carsismo ed alla evoluzione neogenica di questo territorio rappresentano i principali punti di interesse naturalistico. la presenza di campi carreggiati, di doline con dimensione ed origine differenti (le più spettacolari e conosciute sono quelle del “pulo” e del “pulicchio” nell’area compresa fra altamura e gravina), di numerose “gravine” (strette forre di origine fluviale profonde anche fino a 100 m e connesse al sollevamento medio-suprapleistocenico dell’area) e di numerose cavità carsiche rende quest’area di indubbio interesse anche dal punto di vista scientifico. nell’area del parco ricadono anche la famosa grotta carsica di lamalunga (nella quale è stato rinvenuto “l’uomo di altamura”) e la cava con le celeberrime tracce di locomozione di dinosauri (cava ex-de lucia in località pontrelli – iannone, 2003). negli ultimi 20 anni l’area delle murge alte è stata soggetta a profondi mutamenti connessi all’azione antropica rappresentata soprattutto da una generalizzata azione di “miglioramento fondiario” (giglio et al., 1996): le pratiche utilizzate (soprattutto “spietramento” s.l.), in combinazione con l’introduzione di coltivazioni a 324 m. moretti et al., fig. 1. a carta geologica schematica delle murge (da pieri et al., 1997 modificata). b: sezione geologica schematica attraverso l’altopiano delle murge (da pieri et al., 1997 modificata). c: carta schematica della distribuzione delle paleolinee di costa dei terrazzi marini del pleistocene medio-superiore (da ciaranfi et al., 1988 modificata). a: simplified geologic map of the murge area (modified from pieri et al., 1997). b: simplified geologic section along the murge area (modified from pieri et al., 1997). c: map of the coastlines of the marine terraced deposits (middle-late pleistocene modified from ciaranfi et al., 1988). carattere più o meno intensivo, accelerano irrimediabilmente i processi erosivi ad opera delle acque meteoriche e del vento (pieri et al., 1999). gli effetti di tali pratiche non sono ristretti alla sola area delle murge alte, ma si risentono, con intensità e modalità differenti, anche nell’adiacente settore costiero pugliese (moretti, 1998; moretti et al., 1998). nel corso degli anni le aree soggette a “miglioramento fondiario” sono via via andate aumentando; allo scopo di quantificarle in modo accurato, sono state messe a punto alcune procedure di calcolo automatico di aree attraverso fotointerpretazione di immagini da satellite (fiore et al., 1995; ekuakille et al., 2000). una forte politica di sovvenzioni pubbliche (programmi integrati mediterranei della comunità europea e l.r. 51/81) ha consentito di estendere la pratica dello spietramento s.l., trasformando in terreni agricoli gran parte dell'area precedentemente destinata a pascolo (aa.vv., 2002). in questo studio si cercherà di evidenziare la stretta relazione fra uso del suolo ed erosione nell’area delle murge con particolare riferimento alle forme diffuse di dissesto idrogeologico s.l. che si registrano nell’ultimo decennio sia nei settori interni e carsici delle murge (murge alte) che nei settori costieri (costa adriatica e ionica delle murge). 2. inquadramento geologico l’avampaese apulo rappresenta il settore di avampaese del sistema orogenico dell’appennino meridionale nel plio-pleistocene (d’argenio et al., 1973). l’avampaese apulo emerso è costituito da tre settori di alto strutturale relativo (rispettivamente, da n a s, gargano, murge e salento) separati da zone di faglia orientate all’incirca e-o. le murge (fig. 1a e b) rappresentano il settore di alto relativo intermedio dell’avampaese apulo emerso limitato a nord dal graben dell’ofanto e a sud dalla soglia messapica (pieri, 1980; iannone & pieri, 1982; ricchetti et al., 1988). a partire dal pliocene, l’evoluzione geodinamica e stratigrafica di questo settore dell’avampaese apulo è strettamente controllata dalla migrazione verso e del sistema orogenico appenninico e dalla conseguente fase di subsidenza che porta al progressivo annegamento di estesi settori di alto strutturale (doglioni et al., 1994; pieri et al., 1997): durante tale fase di subsidenza sedimentano le formazioni della calcarenite di gravina e delle argille subappennine (pliocene superiorepleistocene inferiore ciaranfi et al. 1988) che affiorano con spessori e caratteri stratigrafici molto variabili lungo i bordi e nei settori morfologicamente meno elevati delle murge (fig. 1.a e 1.b). dalla fine del pleistocene inferiore fino all’attuale, l’avampaese apulo è soggetto ad un intenso sollevamento (interpretato in letteratura in modi assai differenti – ricchetti et al., 1988; doglioni et al., 1994; de alteriis, 1995; gambini & tozzi, 1996). in questo intervallo temporale sedimentano i depositi regressivi della fossa bradanica (pleistocene inferiore) ed i depositi marini terrazzati (pleistocene medio-superiore) che segnano la graduale riemersione delle murge (fig. 1.b) lungo il versante ofantino, bradanico, ionico ed adriatico (ciaranfi et al., 1988). l’altopiano delle murge alte, posto oltre i 500 m di quota (fig. 1.b) non è stato quindi interessato dall’in325effetti dei “miglioramenti fondiari” ... gressione plio-pleistocenica: è caratterizzato da estesi affioramenti di calcari mesozoici che, a partire dalla loro emersione avvenuta nel cretaceo superiore, hanno subito intensi fenomeni carsici non obliterati dalla successiva azione erosiva marina. a quote meno elevate (da 500 m s.l.m. fino al livello del mare attuale), alla morfologia carsica si sono sovrapposti gli effetti dell’ingressione marina plio-pleistocenica e della successiva fase di sollevamento regionale che ha portato alla formazione di 16 ordini di terrazzi marini posti via via a quote decrescenti (fig. 1.c ciaranfi et al., 1988). le murge vengono suddivise in murge alte e murge basse proprio in base al livello massimo raggiunto dal mare nell’ingressione plio-pleistocenica che grande influenza ha avuto nell’evoluzione del paesaggio. anche i suoli (oggetto del prossimo paragrafo) sviluppatisi nei due differenti settori delle murge presentano differenze che richiamano tale diversa evoluzione plio-quaternaria. 3. principali caratteri geo-pedologici e generalità sull’uso del suolo i suoli delle murge alte rappresentano il risultato di un insieme complesso di processi pedogenetici che si sono instaurati sui prodotti residuali della dissoluzione dei calcari mesozoici. essi presentano una composizione granulometrica tendenzialmente argillosa con scheletro abbondante costituito da frammenti di rocce calcaree con dimensioni molto variabili. si tratta di "litosuoli" con spessori esigui originatisi su calcari quasi affioranti (fig. 2), costituiti da un solo orizzonte omogeneo (spesso eccezionalmente 30-40 cm) risultante dalla mescolanza di humus, materiale argilloso ed abbondanti frammenti litici calcarei. suoli con spessori maggiori ed accenni di stratificazione in orizzonti si rinvengono solo in aree ristrette, in pratica solo sul fondo delle depressioni carsiche e delle incisioni fluviali, localmente denominate “lame”. la struttura dei litosuoli delle murge alte è spesso grumosa, con humus generalmente abbondante (talvolta superiore al 10%); risultano essere tendenzialmente aridi poiché le acque meteoriche si infiltrano rapidamente nel substrato rappresentato dai calcari permeabili per fratturazione e carsismo. i suoli delle murge basse presentano spessori maggiori e sono spesso formati da più orizzonti. si sono sviluppati sia sui calcari cretacei che sulle unità più recenti, rappresentate dalla calcarenite di gravina, depositi marini terrazzati e, più raramente, depositi continentali di tipo alluvionale o cineritico: si tratta generalmente di suoli di tipo “rendzina”. fig. 2 profilo di un tipico litosuolo delle murge alte. si noti la presenza di un abbondante scheletro calcareo e del substrato roccioso quasi affiorante. typical soil profile in the murge alte area. note the presence of abundant calcareous rock fragments in the soil and the outcropping bedrock. 326 ii territorio delle murge alte, ed in particolare delle murge nord occidentali, fino a pochi decenni fa, era utilizzato esclusivamente a pascolo. la mancanza di spessori adeguati di suolo, la massiccia presenza di scheletro calcareo e la cronica mancanza d’acqua nelle aree considerate (sia per la mancanza di precipitazioni che per l’elevata percentuale di acqua di infiltrazione tipica di un territorio carsico maturo) hanno storicamente e socialmente determinato una vocazione sostanzialmente legata all’allevamento di ovini e subordinatamente bovini ed equini. le coltivazioni erano limitate alle sole aree nelle quali lo spessore del suolo ne permetteva lo sfruttamento senza particolari lavorazioni (depressioni tettoniche, doline, fondi delle “lame”). in queste aree manualmente si allontanavano i clasti calcarei che venivano in seguito utilizzati nella costruzione di muretti a secco o, su lievi pendii, per dar vita ai caratteristici terrazzamenti in pietra sbozzata (nicod, 1992). nelle murge basse invece l’agricoltura è ben sviluppata (generalmente non si tratta di colture intensive, ma in gran prevalenza solo di viti, ulivi e mandorli) grazie alla presenza di apprezzabili spessori di suolo ed alla presenza sia di falde superficiali libere che una relativa bassa profondità della falda carsica. 4. i “miglioramenti fondiari”: uso del suolo ed erosione nelle murge alte a partire dagli anni ’80 sono state introdotte imponenti sistemazioni agrarie meccanizzate (figg. 3 e 4), incentivate da diversi finanziamenti pubblici. il “miglioramento fondiario” consiste principalmente nell’eliminazione dello scheletro calcareo. per questo scopo sono state ideate macchine dotate di “scarificatori” in grado di staccare interi blocchi di calcare dal substrato roccioso e “frantumatori” in grado di operare la “frangitura” delle pietre in campo (figg. 3 e 4). gli estesi interventi di "spietramento" e "frantumazione" meccanica (fino alla polverizzazione) del complesso suolo-roccia calcarea affiorante nelle murge alte sono oggi estesi a gran parte dei terreni precedentemente destinati a pascolo (fig. 5a). lo spietramento e la frantumazione sono operazioni dirette sia a migliorare la costituzione granulometrica del terreno che a favorire l'accessibilità del campo alle macchine da lavoro. lo spietramento consiste nell'eliminazione dello scheletro calcareo e viene maggiormente utilizzato nelle aree in cui lo spessore del suolo è dell'ordine del mezzo metro; per spessori più esigui, l'eliminazione dello scheletro calcareo porta ad una diminuzione del volume di suolo sfruttabile, non compatibile con alcuna coltura. in queste aree si preferisce far ricorso ad interventi di frantumazione che, conservando immutato il volume di suolo, elimina, triturandola, la frazione più grossolana (figg. 5b e c), costituita dai frammenti calcarei. il terreno risultante presenta maggiore lavorabilità, una costituzione granulometrica arricchita in particelle fini (fino al 50% in più, dopo il settimo passaggio della macchina frangipietre) e una migliore capacità idrica (cioè una migliore capacità di trattenere acqua), per l'aumento dei pori di minori dimensioni. le tecniche di miglioramento fondiario descritte hanno però effetti immediati anche sull'entità dell'azione erosiva: il terreno perde la struttura grumosa primaria ed acquista un nuovo costituente (con granulometria variabile a seconda della macchina utilizzata e del numero di passaggi) che, a tutti gli effetti, si comporta da "inerte". la coesione all'interno del suolo e fra il suolo ed il substrato risulta drasticamente diminuita, specie se gli attrezzi utilizzati regolarizzano la morfologia del tetto del substrato, staccandone piccole parti. anche il tipo di coltura può influenzare in modo importante l'azione erosiva delle acque meteoriche: colture come il grano duro (anch’esso introdotto in modo intensivo solo negli ultimi venti anni) infatti accentuano la naturale predisposizione di queste aree alla perdita di suolo. dalla semina (ottobre-novembre) alla mietitura (giugno-luglio) il suolo può considerarsi coperto parzialmente per soli due mesi. da luglio fino alla germinazione della nuova semina il terreno è nudo e soggetto a fig. 4 operazioni di frangitura nelle murge alte. si noti la trasformazione dei blocchi calcarei frammisti a suolo in un aggregato finissimo polverulento. crushing operations in the murge alte area. note the mechanical reduction of the grain size. fig. 3 operazioni di frangitura nelle murge alte. lo scheletro calcareo ed i frammenti di substrato presenti nel campo vengono triturati meccanicamente. crushing operations in the murge alte area. rock fragments and pieces of the calcareous bedrock are mechanically destroyed. m. moretti et al., 327 saturare più facilmente il suolo nei mesi di siccità. l’effetto principale di queste tecniche di miglioramento è quello connesso al drastico aumento dell’aliquota di acqua di ruscellamento superficiale a scapito di quella legata all’infiltrazione. studi recenti sono stati mirati alla valutazione quantitativa di questo processo (spilotro, 2003), ma senza dubbio, dal punto di vista qualitativo, esso determina l’aumento dell’erosione areale e lineare e la perdita di suolo soprattutto nelle aree delle murge alte dove le pendenze sono più marcate. trattando l’argomento in modo più generale, i fattori che rappresentano "cause predisponenti" per il fenomeno dell'erosione del suolo possono essere così riassunti: 1) condizioni geolitologiche e idrologiche; 2) caratteristiche pedologiche; 3) condizioni morfologiche (pendenza, esposizione, quota); 4) "aggressività" del clima locale; 5) copertura vegetale; 6) tecniche di sistemazione. i primi quattro punti dovevano rappresentare, come visto, per l'area delle murge alte un grosso ostacolo allo sviluppo di una agricoltura moderna e costituiscono al tempo stesso gli elementi che spiegano la naturale predisposizione dei suoli murgiani all'erosione. i due ultimi fattori sono gli unici sui quali l'azione antropica si esplica direttamente e che paradossalmente sono stati utilizzati per accelerare irrimediabilmente i processi erosivi. 5. forme di dissesto idrogeologico dell’ambiente carsico e costiero gli effetti delle pratiche sistematorie descritte e del nuovo uso del suolo hanno condotto a rapidi mutamenti anche nel paesaggio carsico. in particolare, osservazioni recenti condotte in numerose aree delle murge, mostrano che gli effetti più evidenti di tali pratiche sono connessi all'instaurarsi di fenomeni diffusi di dissesto idrogeologico. esempi di dissesto idrogeologico e di rapido mutamento della morfologia carsica sono segnalati all'interno delle depressioni carsiche delle murge alte. la dolina del "pulo" di altamura rappresenta l’elemento carsico più spettacolare e conosciuto dell’area delle murge alte (fig. 6). nel suo intorno, nel corso degli ultimi decenni, gli interventi di spietramento e la messa a coltura dei suoli (fig. 6) hanno parzialmente obliterato i naturali canali di deflusso dell’acqua superficiale e compromesso in modo importante i rapporti fra la percentuale dell’acqua di ruscellamento superficiale e le aliquote di evapotraspirazione ed infiltrazione. in seguito alle precipitazioni autunnali dello scorso anno si è prodotta una estesa conoide alluvionale (fig. 7) nella quale è possibile distinguere i subambienti di conoide prossimale e distale (figg. 8 e 9). la porzione distale, caratterizzata da depositi finissimi siltosi ha occluso l’inghiottitoio carsico della dolina. l’acqua piovana sosta per mesi sul fondo del pulo di altamura originando uno stagno-palude. i cambiamenti dell'uso del suolo (grano al posto del pascolo – fig. 6) e gli interventi di spietramento nelle aree circostanti sono le principali cause predisponenti per l'instaurarsi di questo tipo di dissesto. ancor più gravi dal punto di vista paesaggistico ed economico sono stati gli effetti degli eventi alluvionali nelle aree carsiche e costiere delle province di bari fig. 5 murge alte: a. foto delle differenze macroscopiche fra il suolo adibito a pascolo (a sinistra) ed il terreno “spietrato” (a destra); b. particolare della foto 5a, si noti la presenza del substrato calcareo quasi affiorante; c. particolare della foto 5a, si noti la riduzione di granulometria dello scheletro calcareo dopo un solo passaggio della macchina frangipietre. murge alte area: a. photo showing the differences between the grazing soil (on the left) and the “crushed” soil (on the right); b. a close up of the photo 5.a, in the “natural” soil, calcareous bedrock is outcropping; c. a close up of photo 5.a, note the grain size reduction of the calcareous fragments after an only one passage of the crushing machine. forte erosione a causa dei brevi e violenti temporali estivi e del primo autunno. inoltre dopo la mietitura i terreni vengono "preparati" a questa forte fase erosiva attraverso la profonda aratura che viene effettuata per far effetti dei “miglioramenti fondiari” ... 328 e taranto. negli ultimi dieci-quindici anni, sul litorale adriatico delle murge è chiaramente aumentato il trasporto solido dei corsi d’acqua effimeri (“lame”): essi danno vita negli ultimi anni ad insoliti eventi di piena lungo il litorale adriatico delle murge caratterizzati da elevata energia e trasporto di terra rossa che colora il mare per giorni. alluvionamenti ed allagamenti sono diventati negli ultimi anni nella provincia di bari una nuova ed inaspettata emergenza ambientale (moretti, 1998; moretti et al., 1998). la provincia di taranto è stata recentemente interessata da eventi alluvionali di elevata energia che hanno provocato ingenti danni economici. nell'area di massafra la "gravina" è stata alluvionata da ingenti spessori di sedimenti finissimi provenienti dalle aree "spietrate" poste a monte della cittadina (fig. 10). più a valle (area di palagiano), lo stesso evento alluvionale ha prodotto danni ingenti alle coltivazioni e alle vie di comunicazione (fig. 11). i dissesti descritti se, da una parte non presentano certo i caratteri delle calamità naturali che caratterizzano molti settori della nostra penisola, dall’altra rapfig. 8 un particolare di fig.7 nel settore prossimale ghiaioso della conoide alluvionale. a detail of fig. 7 in the proximal gravelly part of the alluvial fan. fig. 9 un particolare di fig.7 nel settore distale siltoso della conoide alluvionale. a detail of fig. 7 in the distal silty part of the alluvial fan. fig. 7 l’estesa conoide alluvionale recentamente formatasi all’interno del pulo d’altamura. the large alluvial fan in the internal part of the “pulo d’altamura” doline. fig. 6 foto area della dolina del pulo di altamura. le aree circostanti sono state trasformate da aree di pascolo a terreni spietrati e campi di grano. aerial view of the “pulo d’altamura” doline. land use in the surrounding area is restricted to crushed soils and cornfields. m. moretti et al., presentano un segno inequivocabile degli effetti delle sistemazioni agrarie sul paesaggio carsico e costiero di queste aree. 6. conclusioni il complesso degli effetti osservati (erosione accellerata e dissesto idrogeologico l.s.) è direttamente connesso agli interventi di "miglioramento fondiario”, che, nel giro di appena due decenni, hanno irrimedialmente prodotto i seguenti effetti: 1) distruzione del complesso suolo-roccia a seguito delle operazioni di scarificazione, spietramento e frantumazione; 2) produzione di grandi quantità di particelle fini nello scheletro del neo-suolo artificiale, frazioni fini dotate di scarsa o nulla coesione che possono essere facilmente trasportate dagli agenti atmosferici (vento e pioggia); 3) aumento dell'erosione del 329 fig. 11. dettaglio dei danni prodotti nell’area di palagiano durante lo stesso evento alluvionale di fig. 10. detail of damages produced in the coastal palagiano area during the same flood event of fig 10. fig. 10. foto area della gravina di massafra. si noti la presenza dei depositi alluvionali siltosi formati durante l’ultimo evento alluvionale (autunno 2003). aerial view of the gravina di massafra river. note the presence of the thick silty alluvium deposits sedimented during last flood event (autumn 2003). effetti dei “miglioramenti fondiari” ... suolo; 4) distruzione del paesaggio carsico superficiale (lame, doline, campi carreggiati, ecc.) e alterazione del sistema carsico sotterraneo (ipogeo); 5) diminuzione delle quantità d'acqua d'infiltrazione, aumento dell'acqua di ruscellamento superficiale ed alterazione dei processi di ricarica della falda carsica. il danno ambientale prodotto non riguarda purtroppo quindi solo gli aspetti connessi al paesaggio carsico (che doveva essere nelle intenzioni la principale attrattiva del neonato parco nazionale dell’alta murgia) delle murge alte, ma nel giro di pochi anni ha coinvolto le adiacenti aree costiere determinando localmente anche ingenti danni economici. la comunità scientifica per anni si è divisa sugli effetti reali di queste pratiche (una contrapposizione che in termini semplicistici potremmo schematizzare come geologi contro agronomi); oggi, che gli interventi di “miglioramento fondiario” sono ormai estesi a gran parte dell’originaria area adibita a pascolo (aa. vv., 2003), il danno ambientale si è ormai irrimediabilmente prodotto: gli sforzi della ricerca dovranno essere quindi orientati in futuro all’individuazione di soluzioni tecniche volte alla rinaturalizzazione delle aree spietrate e/o a mitigare gli effetti dell’erosione diffusa e concentrata. inoltre tale approccio dovà tener conto forzatamente degli altri impatti antropici ringraziamenti desideriamo ringraziare un anonimo referee per la revisione critica del manoscritto. un sentito ringraziamento va al centro altamurano ricerche speleologiche per averci fornito informazioni e materiale fotografico sul pulo d’altamura. questo lavoro è stato eseguito con finanziamenti m.i.u.r. 2001, 2002 e 2003 (resp. l. sabato) e cofin 2002 (resp. naz. l. simone, resp. locale a. laviano). bibliografia aa. vv. 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(1994) the puglia uplift (se italy): an anomaly in the foreland of the apenninic subduction due to buckling of a thick continental lithosphere. tectonics, 13, 5,1309-1321. ekuakille, a. l., moretti m., pieri p., tralli f., & tropeano, m. (2000) spectral characterization of soil by using ers-2/sar satellite images. gndci 2012, mediterranean storms (ed. claps & siccardi), 615-626. fiore a., loizzo r., moretti m., pappalepore m. & tropeano m. (1995) il telerilevamento da satellite per l'osservazione dello "spietramento" nelle aree carsiche delle murge. applicazione su un'area campione (murgia materana). telerilevamento g.i.s. e cartografia al servizio dell'informazione territoriale. atti del vii conv. naz. ass. it. di telerilevamento, 373-381. chieri (to) 17-20 ottobre 1995. gambini r. & tozzi m. (1996) tertiary geodynamic evolution of southern adria microplate. terra nova, 8, 593-602. giglio g., moretti m. & tropeano m. 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(1992) muretti e terrazze di coltura nelle regioni carsiche mediterranee. itinerari speleologici, serie ii, n° 6, 9-18, 1992. pieri p. (1980) principali caratteri geologici e morfologici delle murge. murgia sotterranea, boll. speleo. martinese, ii/2,13-19. pieri p., festa v., moretti m. & tropeano m. (1997) quaternary tectonic activity of the murge area (apulian foreland, southern italy). annali di geofisica, xl/5, 1395-1404. pieri p., giglio g. moretti m., tralli f., tropeano e. & tropeano m. (1999) pratiche di spietramento e impoverimento dei suoli in aree carsiche: il caso delle murge alte. ii forum internazionale sulla desertificazione: azioni italiane a sostegno della convenzione delle nazioni unite per combattere la desertificazione. 243-246 e 217-220 nella versione in inglese. ricchetti g., ciaranfi n., luperto sinni e., mongelli f. & pieri p. (1988) geodinamica ed evoluzione sedimentaria e tettonica dell'avampaese apulo. mem. soc. geol. it., 41, 57-82. spilotro g. (2003) modificazioni antropiche delle tessiture dei suoli carsici dell’alta murgia e finalizzazione agricola: implicazioni idrogeologiche. riassunti fist, bellaria 2003. 330 ms. ricevuto l’11 maggio 2004 testo definitivo ricevuto il 16 novembre 2004 ms. received: may 11, 2004 final text received: november 16, 2004. m. moretti et al., imp. messina & sseeddiimmeennttii ee ffoorrmmee qquuaatteerrnnaarrii nneellll’’aallttaa vvaallllee ddeellll’’aatteerrnnoo ((ll’’aaqquuiillaa)) ppaaoolloo mmeessssiinnaa11,, ccaarrlloo bboossii11 && mmaarrccoo mmoorroo22 1istituto di geologia ambientale e geoingegneria del cnr via del fosso del cavaliere, 100 00133 roma e-mail: ; p.messina@igag.cnr.it; c.bosi@igag.cnr.it 2istituto nazionale di geofisica e vulcanologia via di vigna murata, 605 00143 roma e-mail: moro@ingv.it riassunto l’area studiata si sviluppa lungo la valle del fiume aterno e, nei pressi di arischia, è caratterizzata dalla presenza di un’ampia conca che ospita significativi spessori di depositi continentali quaternari. in particolare, nell’area compresa tra s. giovanni ed il versante sudoccidentale del m. pettino, è stata riconosciuta una complessa successione di eventi deposizionali ed erosivi che sono stati sintetizzati in uno schema allo-morfosequenziale ottenuto dall’integrazione di unità allostratigrafiche e unità morfosequenziali cronologicamente ordinate. queste ultime corrispondono a superfici relitte, sia di erosione che di accumulo, variamente disposte alla sommità dei rilievi e lungo i versanti della valle e scolpite sia nel substrato marino che nelle unità continentali. in totale sono state riconosciute 19 unità morfosequenziali e 11 unità allostratigrafiche dalla cui integrazione sono state ottenute 8 unità allo-morfosequenziali. gli elementi cronologici di tipo strumentale (analisi paleomagnetiche e determinazioni radiometriche) disponibili per sei unità allostratigrafiche, nonché alcune indicazioni ottenute da tentativi di correlazione con unità presenti in altri bacini della regione, hanno permesso di formulare un’ipotesi di inquadramento cronologico (dal pliocene al pleistocene superiore) per alcune delle unità riconosciute. l’analisi di questa successione ha permesso di delineare una situazione caratterizzata dal progressivo incassamento di forme e litosomi che viene a corrispondere alle varie fasi del progressivo approfondimento del reticolo idrografico. questo tipo di evoluzione geologica risulta essere condizionata in modo determinante dall’attività, anche recente, di due strutture tettoniche riconoscibili alla base dei versanti sud-occidentali rispettivamente di m. marine e di m. pettino. abstract the investigated area is located in the aterno valley river, abruzzi apennines. the sector of arischia is represented by a wide valley with numerous outcrops of continental quaternary deposits. in particular, in the area between s. giovanni and the south western side of mt. pettino, a complex succession of depositional and erosive events has been defined. these events have been summarised in an allo-morphosequential scheme obtained by the integration of allostratigraphic units and morphosequential units, which have been put in chronological order. the latter units correspond to relict surfaces (due to erosion or accumulation), variously located at the summit of the reliefs or along the flanks of the valley, sculptured in both marine substrata and in the continental units. in the surveyed area a total of 8 allo-morphosequential units have been defined through the integration of 19 morphosequential units and 11 allostratigraphic units. the chronological data (magnetic polarity and radiocarbon data), available for 6 allostratigraphic units, as well as indications derived from of correlations with units of adjacent intermountain basins, allowed to make a hypothesis about a chronological framework (between the pliocene and the late pleistocene) for some of the defined units. the analysis of this succession led to defined a geological evolution represented by the progressive embedding of erosive and depositional landforms and lithosomes, representing the progressive deepening phases of the hydrographic network. this geological evolution has been conditioned by the activity, even recent, of two faults affecting the bottom of the south western slopes of mt. marine and mt. pettino, respectively. parole chiave: quaternario, conche intermontane, appennino centrale. keywords: quaternary, intramountain basin, central apennines il quaternario italian journal of quaternary sciences 1166(2), 2003, 231-239 11.. pprreemmeessssaa la zona alla quale si riferisce questa nota è rappresentata dal tratto della valle dell’aterno compreso fra la stretta di s. giovanni ed il bordo settentrionale della conca aquilana, ad ovest della catena del gran sasso. essa è costituita da un’ampia conca a fondo pianeggiante, sviluppata lungo il fondovalle del fiume aterno e delimitata dal versante sw del m. marine e dalle propaggini ne del gruppo del m. giano. la conformazione e l’evoluzione geologica della conca è strettamente condizionata dall’attività delle faglie che hanno originato, come espressione morfologica, i versanti sud-occidentali del m. marine e del m. pettino (fig. 1). l’assetto generale dell’area, molto simile a quelle di molte depressioni intermontane abruzzesi, corrisponde ad un complicato insieme di superfici di erosione e di accumulo, in vario rapporto con litosomi quaternari costituiti da sedimenti fluviali e lacustri e da depositi di versante. questi poggiano in discordanza su sequenze carbonatiche e su depositi terrigeni miocenici, affioranti solo nella porzione settentrionale della valle dell’aterno. i dati geologici, geomorfologici e tettonici disponibili nella bibliografia geologica sono quelli riportati in bosi (1975), blumetti (1995), bagnaia et al. (1996), blumetti et. al. (1996), basili et al. (1997), basili et al. (1999), messina et al. (2001) e moro et al., (2002). l’area studiata è stata recentemente oggetto di un rilevamento eseguito nell’ambito di un progetto per la 232 p. messina, c. bosi & m. moro redazione di carte prototipali finanziato dal servizio geologico nazionale e dal cnr. i risultati di interesse cartografico sono riportati in bosi et al. (2003); quelli di più specifico interesse stratigrafico-evolutivo sono contenuti nei paragrafi che seguono. 22.. aassppeettttii mmeettooddoollooggiiccii i sedimenti quaternari presenti nella zona studiata, come del resto nella maggior parte delle conche intermontane dell’appennino laziale-abruzzese, hanno caratteristiche (uniformità delle litofacies, scarsità degli elementi di datazione, difficoltà di correlazioni, ecc.) che ostacolano una dettagliata ricostruzione dell’evoluzione geologica nei suoi diversi aspetti (stratigrafico, geomorfologico, tettonico). proseguendo in una prospettiva di ricerca già seguita da tempo (bertini e bosi, 1993) lo studio stratigrafico è stato quindi integrato dall’esame della successione delle superfici relitte, rappresentate essenzialmente da spianate di accumulo e da superfici di erosione. le prime sono quelle sviluppate a tetto di litosomi di origine genericamente fluviale. le seconde sono rappresentate da superfici, pianeggianti o comunque a bassa energia di rilievo, scolpite nelle rocce del substrato o più raramente in terreni quaternari; esse sono probabilmente legate a fenomeni di erosione laterale realizzatisi durante stazionamenti di antichi livelli di base locali (bosi et al., 1996). rinviando per maggiori dettagli a bosi et al. (2003) ci si limita in queste sede a ricordare che l’insieme delle superfici identificate è stato utilizzato integrandolo con gli elementi di ordine stratigrafico mediante le operazioni seguenti: a) equiparazione delle forme fossili (unità morfologiche), assunte come indicatori di eventi erosivi o deposizionali, alle unità stratigrafiche, assunte come prodotti di specifici eventi deposizionali (bosi et al., 2003 e relativa bibliografia); b) definizione di una corrispondenza cronologicamente ordinata fra la “successione morfosequenziale”, costituita da unità morfologiche, e la successione stratigrafica, costituita in questo caso da unità allostratigrafiche; c) definizione di “unità allo-morfosequenziali” (uam) sulla base dell’integrazione di unità morfosequenziali (um) con unità allostratigrafiche (ua); d) collocazione di queste unità in una “successione allo-morfosequenziale” unitaria. in questa successione (fig. 2) sono state collocate anche superfici di erosione scolpite nel substrato mesocenozoico, prive di rapporti diretti con unità stratigrafiche quaternarie. fig. 1 ubicazione dell’area di studio. 1, faglia diretta (a) e suo probabile prolungamento (b); i trattini indicano il lato ribassato. location of the investigated area. 1, normal fault (a) and possible prolongation (b); hatching on downthrown side. 33.. llaa ssuucccceessssiioonnee aalllloo--mmoorrffoosseeqquueenn-zziiaallee una sintesi stratigrafico-geomorfologica dell’area esaminata può essere delineata a partire dai lembi di antichi paesaggi probabilmente pliocenici (galadini et al., 2003 e relativa bibliografia) conservati alla sommità dei rilievi ed in particolare nella zona di m. marine. incassati in essi sono stati riconosciuti alcuni lembi di spianate erosive, molto rimodellati, presenti sulla destra dell'aterno nella zona di cagnano amiterno (a-f di fig. 2). segue poi una complicata successione di superfici di erosione e di litosomi continentali (talora con le relative superfici di accumulo) progressivamente incassati a costituire una successione terrazzata che differisce da quelle usualmente considerate per il fatto che comprende anche le superfici di erosione scolpite nel substrato carbonatico, del tutto equiparabili alle usuali superfici terrazzate. applicando a questa successione il procedimento sopra indicato sono state definite 19 unità morfosequenziali e 11 unità allostratigrafiche, dalla cui integrazione sono state ottenute le 8 unità allo-morfosequenziali che compaiono nella schema di fig. 2. come risulta da questo schema, tutte le unità riconosciute, indipendentemente dal fatto che si tratti di unità morfologiche o stratigrafiche, sono state numerate progressivamente, dalla più recente (sedimenti alluvionali dell’attuale fondovalle, 1) alla più antica (superficie di erosione a letto dei sedimenti continentali più antichi, 271). ogni unità allo-morfosequenziale è stata poi indicata con due numeri che rappresentano l’elemento più antico e quello più recente che costituiscono l’unità stessa. 233sedimenti e forme quaternari ... le caratteristiche principali delle unità istituite possono essere sintetizzate come segue. uam 26/27 l’unità allostratigrafica 26 è costituita da conglomerati ad elementi carbonatici poco elaborati e da alternanze di livelli ghiaiosi con ciottoli arenacei e calcarei molto elaborati e livelli sabbioso-limosi. lo spessore minimo dell’unità è di circa 60 metri. l'intera successione presenta giaciture differenti da quelle primarie, con inclinazioni degli strati che raggiungano in alcuni casi circa 20°, verso nord-est (fig. 3). questa unità, stratigraficamente più antica dell’ua 21 (caratterizzata da polarità magnetica inversa, v. sotto), presenta polarità normale (messina et al., 2001). essa risulta essere quindi verosimilmente più antica di 1,770 ma (l’età dei limiti dei croni è riferita a cande e kent, 1995) e riferibile dunque ad un generico pliocene. um 23-24-25 sono costituite da lembi di spianate di erosione rimodellate, scolpite nel substrato e sviluppate a quote comprese tra 750 e 850 m s.l.m. (fig. 4). uam 21/22 l’ua 21 è costituita da ghiaie fluviali, talora sabbioso-limose, con elementi generalmente ben arrotondati (dimensioni variabili fino a 20 centimetri), localmente con intercalazioni sabbioso–limose con livelli ossidati. la stratificazione immerge nel quadrante di sw, con inclinazioni che raggiungono i 10°. l’embricatura dei ciottoli indica una direzione di trasporto da nw a se, mediamente parallela al corso attuale dell’aterno. lo spessore minimo dell’unità è di circa 30 metri. la parte alta dell’unità è troncata da una superficie di erosione su cui poggiano ghiaie fluviali, di pochi metri di spessore e con giaciture generalmente suborizzontali, appartenenti a successivi cicli sedimentari, non definibili nel dettaglio. come già accennato precedentemente, fig. 2 schema dei rapporti morfologico-stratigrafici. morpho-stratigraphic framework. 1 ad ogni numero è stata associata una sigla che ne chiarisce la natura (se=superficie di erosione; sa=superficie di accumulo; li= litosoma). 234 questa unità presenta polarità magnetica inversa ed è quindi probabilmente riferibile al pleistocene inferiore (croni inversi c1r e c1r.1r, età tra 0,780 e 1,770 ma secondo cande e kent, 1995). uam 18/20 l’unità allostratigrafica 19 è costituita da limi sabbioso-argillosi ben stratificati, a luoghi laminati, a giacitura generalmente suborizzontale. questi strati (spessore affiorante 15 m circa) rappresentano un deposito di fine ciclo fluviale passante verso l’alto ad ambiente lacustre. questa unità, più recente dell’ua 21, è caratterizzata da polarità magnetica normale; è possibile assumere che si sia deposta durante il crono normale brunhes e che sia quindi più recente di 0,780 ma. l’unità è delimitata a tetto dalla superficie di accumulo (um 18) ben conservata e riconoscibile a nw di barete a quota 780-800. fig. 3 ghiaie fluviali basculate dell’unità allostratigrafica 26. tilted fluvial gravels related to the allostratigraphic unit 26. fig. 4 unità morfosequenziale um25 scolpita nel substrato carbonatico e sospesa sui depositi continentali nei pressi di arischia. morphosequential unit um25 carved into the carbonate bedrock and suspended over the continental deposits in the area of arischia. p. messina, c. bosi & m. moro 235 um 17 corrisponde ad alcuni lembi di superfici di erosione a nord di s. vittorino, a quota 710-800 m, probabilmente riconducibili ad un episodio di spianamento unitario, che ha interessato in modo indifferenziato sia il substrato calcareo che le unità allostratigrafiche 26 e 21 (figg. 5 e 6). uam 14/16 l’unità allostratigrafica 15 è costituita da 10 metri circa di sabbie fini limose con rari ciottoli calcarei poco arrotondati, deposte in un ambiente di tipo fluviale di bassa energia. anche se gli affioramenti sono limitati per numero e per dimensione, in questa unità, come nelle precedenti, non sono stati osservati minerali di orifig. 5 ghiaie fluviali e livelli di sabbie e limi dell’unità allostratigrafica 21. alla sommità dei depositi è visibile l’unità morfosequenziale 17 (vedi anche figura 6). fluvial gravels with sandy and silty levels related to the allostratigraphic unit 21. see the morphosequential unit 17 on the top of the deposits (see also figure 6). fig. 6 unità morfosequenziale 17. sullo sfondo è visibile la scarpata di faglia di m. marine. morphosequential unit 17. see the mt. marine fault scarp in the background. sedimenti e forme quaternari ... 236 gine vulcanica. per questo motivo potrebbe collocarsi nella parte bassa del pleistocene medio (fornaseri, 1985; narcisi e sposato, 1989). l’unità è delimitata a tetto dalla corrispondente superficie di accumulo (um14) conservata in lembi rimodellati nella zona di cavallari. lateralmente questa superficie corrisponde ad una spianata di erosione che interessa sia il substrato calcareo che l’ua 21, ad una quota compresa tra 690 e 720 m circa. uam 11/13 l’ua 12 è costituita da livelli suborizzontali di ghiaie fluviali, variamente sabbiose, con elementi molto arrotondati, e da lenti di sabbie che contengono abbondante materiale di origine vulcanica (piccole scorie, pirosseni, biotite, ecc.). lo spessore affiorante dell’unità è di circa 25 metri. questi strati rappresentano la prima unità che è caratterizzata da significativi apporti di minerali vulcanici. l’unità è delimitata a tetto dalla relativa superficie di accumulo (um 11) conservata in lembi a quote 670715, nella zona compresa tra prato lagone e prato dell’agora. um 10 questa unità è costituita da lembi di una spianata di erosione sviluppati a quote 665-675 e scolpiti nell’ua 12 nell’area compresa tra c.le visconti e pratiglio. uam 7/9 l’unità allostratigrafica 8 è costituita da pochi metri di ghiaie sabbioso-limose, di ambiente fluviale ed è delimitata a tetto dalla relativa superficie di accumulo (um 7) conservata in lembi a quote 670-680. uam 4/6 l’unità allostratigrafica 5 è rappresentata da pochi metri di spessore di strati limoso-sabbiosi con livelli a piccoli clasti sub-arrotondati ed è delimitata a tetto da una superficie di accumulo (um 4), ben riconoscibile nella zona di scentella. lateralmente questa superficie corrisponde ad una spianata di erosione che interessa le unità più antiche. uam 1/3 l’unità allostratigrafica 2 è rappresentata da sedimenti fluviali sabbioso-ghiaiosi del fondovalle attuale e da coltri colluviali che ad esso si raccordano, nonché da depositi di versante e da depositi di conoide. essa è delimitata a tetto dalla superficie di accumulo (um 1), che corrisponde all’attuale fondovalle del fiume aterno. nell’ambito dell’area esaminata sono stati riconosciuti anche strati riconducibili a due unità stratigrafiche (“brecce di s. marco” e “brecce di s. antonio) non chiaramente collocabili nell’ambito della successione descritta (fig. 2). brecce di s. marco. si tratta di brecce cementate ben stratificate (fig. 7) costituite da clasti calcarei a spigoli vivi immersi in una matrice calcarea spesso di colore rosa. lo spessore massimo è di circa 50 metri. analisi paleomagnetiche eseguite su alcuni campioni (messina et al., 2001) hanno evidenziato una polarità magnetica inversa, inducendo ad ipotizzare un’età pleistocenica inferiore (croni inversi c1r e c1r.1r, età tra 0,780 e 1,770 ma secondo cande e kent, 1995). brecce di s. antonio si tratta di orizzonti di brecce di pochi metri di spessore costituiti da clasti carbonatici a spigoli vivi in matrice generalmente terrosa di colore bruno. la stratificazione è generalmente a franapoggio e accompagna l’andamento del versante dei rilievi carbonatici. determinazioni radiometriche (c14) eseguite su alcuni livelli contenenti materiale organico intercalati alle “brecce di s. antonio” forniscono un’età variabile tra 31.710±760 e 23.330±300 anni b.p. (galadini e galli, 2000). quanto fino a qui descritto non comprende tutti i depositi riconosciuti. esistono infatti alcuni depositi ai quali non è stato possibile, data la scarsità e la dispersione areale dei modesti affioramenti osservati, attribuire una precisa collocazione stratigrafica. si tratta frequentemente di ghiaie, probabilmente fluviali, con clasti variamente arrotondati, alle quali si intercalano talora orizzonti a clasti con spigoli vivi e livelli sabbiosi. frequenti nei depositi di questo tipo i livelli di sedimenti di suolo, limoso-sabbiosi. sul versante sinistro della valle, sono state inoltre osservate successioni di strati sabbiosi, con intercalazioni di clasti a spigoli vivi, passanti talora a sabbie medio-fini, laminate o, più raramente massive. caratteristica di queste successioni sono le evidenti deformazioni con acquisizione di inclinazione dell’ordine anche della decina di gradi. non si può escludere che queste successioni siano riferibili a fasi deposizionali distinte, che potrebbero portare alla definizione di più unità allostratigrafiche. ad una di queste unità sono da riferire i livelli datati 29.690±1.100 da blumetti (1995). del tutto sporadici sono piccoli lembi di limi calcarei biancastri di origine lacustre. tutti i sedimenti citati affiorano al disotto di coperture detritiche, verosimilmente riferibili ad eventi deposizionali nettamente distinti. data l’impossibilità di chiarire, in modo compatibile con il dettaglio adottato per le altre unità che sono state sopra definite, le caratteristiche stratigrafiche di queste successioni, esse sono state comprese nell’“allogruppo di arischia”. 44.. ccrroonnoollooggiiaa ee ccoorrrreellaazziioonnii in nessuna delle unità stratigrafiche riconosciute sono state rinvenute faune o flore di interesse cronologico. gli unici riferimenti disponibili al riguardo sono quindi quelli strumentali, già indicati nella descrizione delle singole unità. essi possono essere così sintetizzati: ua 26 pliocene; ua 21 e brecce di s. marco pleistocene inferiore; ua 19, ua 15 pleistocene medio; brecce di s. antonio pleistocene superiore. altre indicazioni di significato cronologico possono essere ottenute da tentativi di correlazione con altre unità riconosciute nella regione. l’unità allostratigrafia 26 sembra ragionevolmente p. messina, c. bosi & m. moro correlabile con le “sabbie di piagge” della valle del salto (bertini e bosi, 1976), con la formazione di aielli della conca del fucino (bosi et al., 1995), con la formazione di s. croce nella valle del turano e con la formazione di pianola (bosi et al., 2003). questa correlabilità discende da forti analogie stratigrafiche, geomorfologiche e tettoniche, consistenti nel fatto che tutte queste unità hanno in comune le seguenti caratteristiche: rappresentano il primo importante episodio conservato di sedimentazione continentale che ha interessato le diverse zone; sono le più antiche fra quelle incassate nel paleopaesaggio riferito al pliocene; sono tutte interessate da vistose deformazioni. l’unità allostratigrafica 21 presenta forti spessori e mostra spiccate analogie litologiche e strutturali con le formazioni di cupoli nella conca del fucino (bosi et al., 1995), di pescasseroli nella conca omonima (galadini e messina, 1993), del fosso canalicchio e di madonna della strada, rispettivamente nella valle del salto e nella conca di scoppito (bosi et al., 1989; bosi, 1989). queste formazioni risultano inoltre tutte incassate in quelle citate a proposito della ua 26. le brecce di s. marco hanno caratteristiche litologiche, spessori e rapporti con i versanti del tutto analoghe a quelle delle brecce bisegna (bosi e messina, 1990) e con le brecce di fonte vedice (bertini e bosi, 1993). ambedue queste formazioni sono state riferite al pleistocene inferiore (bosi e messina 1991; bosi et al. 1995; galadini e messina, 1993). questa attribuzione è stata confermata anche da determinazioni di paleomagnetismo da d’agostino et al., 1997). anche i rapporti con le formazioni correlate con l’unità 21 sono sostanzialmente analoghi. per le unità più recenti, l’unico elemento di correlazione (generalmente collocato a qualche centinaio di migliaia di anni (fornaseri, 1985; narcisi e sposato, 1989)) riguarda la prima comparsa di abbondanti minerali vulcanici che, nel caso della zona in esame, si colloca fra le unità allostratigrafiche 15 e 12. sono invece da riferire alla parte alta del pleistocene superiore le brecce di s. antonio (galadini e galli, 2000) ed almeno uno (blumetti, 1995) dei livelli compresi nell’”allogruppo di arischia”. le correlazioni indicate, delineate anche in bosi et al. (2003), bene si inquadrano in precedenti tentativi di correlazione a scala regionale (bosi e messina, 1991) e sono in accordo con le valutazioni espresse sulla base di dati di paleomagnetismo di messina et al. (2001) che, come già indicato, indurrebbero a riferire al pliocene l’unità allostratigrafica 26 ed al pleistocene inferiore l’unità allostratigrafica 21 e le brecce di s. marco. 237 fig. 7 brecce di san marco. san marco breccias. sedimenti e forme quaternari ... 55.. tteettttoonniiccaa tipologia ed entità delle deformazioni tettoniche quaternarie nell’area studiata sono strettamente legate all’evoluzione del sistema strutturale che si sviluppa in corrispondenza delle dorsali di m. marine e di m. pettino (fig. 1) che rappresentano gli elementi strutturali più importanti del sistema di faglie en echelon destro descritto da galadini (1999). la faglia più settentrionale, interna all’area considerata, è la faglia diretta la cui traccia si sviluppa alla base del versante di m. marine. l’attività quaternaria di questa faglia è dimostrata oltre che dalla conformazione stessa del versante di origine chiaramente strutturale, dalla dislocazione delle brecce di s. antonio e da evidenti scarpate di faglia lungo le quali sono state evidenziate dislocazioni in epoca storica (moro et al., 2002). la faglia più meridionale si sviluppa al piede del versante del m. pettino (al di fuori dell’area considerata), e si prolunga fino entro l’area considerata, nella zona di s. marco, ove disloca le brecce omonime. se si prescinde dalle due faglie citate, indizi di strutture di interesse quaternario sono decisamente scarsi, limitati alla zona di cona della croce e di s. vittorino. nella prima zona sono state osservate alcune faglie che interessano orizzonti ghiaiosi della ua 21, con rigetti di pochi decimetri. nella seconda, due deboli e larghe depressioni, difficilmente riconducibili a normali fenomenologie erosive, inducono a ritenere probabile l’esistenza di due piccole faglie ad attività quaternaria che interessano l’unità allostratigrafica 21. altri elementi strutturali di interesse quaternario sono rappresentati da basculamenti verso ne nei depositi ghiaiosi dell’ua 26 a nord ed a ovest di barete. poco più a sud appare basculata verso sse la superficie um 17 presente a tetto dell’ua 21. ambedue queste rotazioni sono verosimilmente riconducibili all’insieme delle dislocazioni che hanno dato origine al vistoso allargamento del fondovalle dell’aterno, scarsamente compatibile con una “normale” escavazione valliva. 66.. eevvoolluuzziioonnee ggeeoollooggiiccaa i dati raccolti non sono sufficienti ad una ricostruzione dettagliata dell’evoluzione geologica del tratto di valle considerato: mancano infatti conoscenze sufficienti sull’evoluzione della zona che si estende a monte e, sopratutto, di quella che si estende più a valle, nella conca aquilana, oltre la stretta di s. vittorino. ci si deve quindi limitare a delineare questa evoluzione solo nella grandi linee. gli eventi più antichi sono quelli che hanno dato origine ai lembi di spianate di erosione riconducibili ad antichi paleopaesaggi attualmente in posizione subsommitale. si tratta di un argomento tuttora oggetto di un vivace dibattito scientifico che verte sopratutto sull’estensione dei singoli paesaggi (galadini et al., 2003 e relativa bibliografia; coltorti e pieruccini, 2000; bosi, 2002). tutti gli autori sono tuttavia d’accordo che questi paesaggi appartengono ad una o più fasi evolutive più antiche dell’inizio del forte sollevamento tettonico che ha condizionato l’approfondimento del reticolo idrografico e, verosimilmente, l’inizio dell’enucleazione dei bacini in conseguenza dei movimenti lungo le faglie distensive che bordano i bacini stessi (galadini et al., 2003). in base a considerazioni di tipo regionale e ad ipotesi di correlazione con altre conche (bosi e messina, 1991; bosi et al., 2003) questo stadio dell’evoluzione geologica è da riferire ad un generico pliocene. successivamente si assiste ad un imponente e progressivo approfondimento dei solchi vallivi, caratterizzato dall’alternanza di fasi a prevalente incisione verticale e a prevalente spianamento laterale, che si è protratta fino ad oggi dando origine alla successione “terrazzata” descritta al paragrafo 4. sulla base dei dati resi disponibili con lo studio eseguito, nell’ambito di questo approfondimento si possono identificare alcune eventi particolari che possono essere così sintetizzati: 1) fase deformativa che dà origine al basculamento dei depositi della unità allostratigrafica 26 e della unità morfosequenziale 27; 2) importante fase di deposizione alluvionale nel corso della quale si sedimentano i forti spessori delle ghiaie dell’unità allostratigrafica 21; 3) importante fase di deposizione delle caratteristiche brecce di s. marco. secondo la valutazione già espressa a proposito dei riferimenti cronologici (v. par. 4) gli eventi 2 e 3, ambedue riferibili al pleistocene inferiore, avrebbero una estensione molto vasta essendo stati riconosciuti in molte località dell’appennino laziale-abruzzese. alla ricostruzione di una evoluzione geologica così schematizzata sfuggono ovviamente gli eventi responsabili della sedimentazione degli strati compresi nell’allogruppo di arischia, che in alcuni casi indurrebbero ad ipotizzare ambienti di tipo lacustre a vari livelli stratigrafici. 77.. ccoonncclluussiioonnii lo studio eseguito ha permesso di delineare un quadro sommario dell’evoluzione geologica dell’area. pur con questi limiti questo quadro ha definito una successione di eventi deposizionali ed erosivi, rappresentati nello schema di fig. 2, che risulta significativamente più completa di quella alla quale si sarebbe pervenuti sulla base di uno studio puramente stratigrafico. si può inoltre ritenere che l’evoluzione geologica schematizzata possa servire comunque a delineare le tappe più importanti del progressivo approfondimento del reticolo, conseguente al sollevamento tettonico manifestatosi nell’appennino centro-meridionale in epoca successiva a quella degli episodi di spianamento probabilmente pliocenici. llaavvoorrii cciittaattii bagnaia r., blumetti a.m., de luca g., gorini a., marcucci s., marsan p., milana g., salvucci r. e zambonelli e. (1996) morfotettonica dei rilievi a nord della conca aquilana. il quaternario, 99 (1), 287-292. basili r., bosi c. e messina p. (1997) la tettonica quaternaria dell'alta valle del f. aterno (appennino centrale) desunta dall'analisi di successioni di superfici relitte. il quaternario, 1100 (2), 238 p. messina, c. bosi & m. moro 621-624. basili r., bosi c. e messina p. (1999) paleo-landsurfaces and tectonics in the upper aterno valley (central apennines). z. geomorph. n.f., suppl.bd. 111188, 17-25. bertini t. e bosi c. (1976) – sedimenti continentali probabilmente pliocenici nella valle del salto e nella conca del fucino (rieti e l’aquila). boll. soc. geol. it., 9955, 767-801. bertini t. e bosi c. (1993) la tettonica quaternaria della conca di fossa (l'aquila). il quaternario, 66 (2), 293-314. blumetti a. m. (1995) neotectonic investigations and evidence of paleoseismicity in the epicentral area of the january-february 1703, central italy, earthquakes. in: serva l. e slemmons d. b. (eds.), a.e.g. special publication no. 66, perspective in paleoseismology, 83-100. blumetti a. m., cavinato g. p. e tallini m. (1996) evoluzione plio-quaternaria della conca di l'aquila-scoppito: studio preliminare. il quaternario, 99 (1), 281-286. bosi c. (1975) osservazioni preliminari su faglie probabilmente attive nell'appennino centrale. boll. soc. geol. it., 9944, 827-859. bosi c. (1989) – tentativo di correlazione fra le successioni plio-pleistoceniche. in "elementi di tettonica pliocenico-quaternaria ed indizi di sismicità olocenica nell'appennino laziale-abruzzese". guida all'escursione della s. g. i., 89-96. esa grafica. bosi c. (2002) – l’interpretazione delle superfici relitte nell’appennino centrale: il caso della zona di colfiorito (prov. perugia e macerata). il quaternario, 1155(1), 69-82. bosi c., caiazzo c., cinque a. e messina p. (1996). le superfici relitte della regione fucense (appennino centrale) ed il loro possibile significato nella ricostruzione della evoluzione geologica. il quaternario, 9966, 381-386. bosi c., galadini f. & messina p. (1995). stratigrafia plio-pleistocenica della conca del fucino. il quaternario, 88 (1), 83-94. bosi c., galadini f., giaccio b., messina p., sposato a. (2003) plio-quaternary continental deposits in the latium-abruzzi apennines: the correlation of geological events across different intermontane basins. il quaternario, 1166(1bis), 55-76. bosi c. e messina p. (1990) elementi di stratigrafia neogenico-quaternaria tra il fucino e la valle del giovenco (l'aquila). mem. descr. carta geol. it., 3388, 85-96. bosi c. e messina p. (1991) ipotesi di correlazione fra successioni morfo-litostratigrafiche plio-pleistoceniche nell'appennino laziale-abruzzese. studi geologici camerti, crop 1111, 275-263. bosi c., messina p. e moro m. (2003) – nuovi procedimenti cartografici per il quaternario continentale: l’esempio della carta geologica dell’alta valle dell’aterno. il quaternario, 1166(1), 127-138. bosi c., messina p. & sposato a. (1989) la depressione del salto. in "elementi di tettonica pliocenicoquaternaria ed indizi di sismicità olocenica nell'appennino laziale-abruzzese". guida all'escursione della s. g. i., 89-96. esa grafica. cande s. c. & kent d. v. (1995). revised calibration of the geomagnetic polarity time scale for the late cretaceous and cenozoic, j. geophys. res. 110000, 6093-6095. coltorti m. e pieruccini p. (2000). a late lower pliocene planation surface across the italian peninsula: a key tool in neotectonic studies. journ. geodynamics, 2299, 323-328. d'agostino, n., speranza, f. e funiciello, r. (1997). le "brecce mortadella" dell'appennino centrale: primi risultati di stratigrafia magnetica. il quaternario, 10 (1), 385-388. fornaseri m. (1985). geochronology of volcanic rocks from latium (italy). rend. soc. it. miner. petrol., 4400, 73-106. galadini f. (1999) pleistocene change in the central apennine fault kinematics, a key to decipher active tectonics in central italy. tectonics, 1188, 877-894. galadini f. e galli p. (2000) active tectonics in the central apennines (italy) – input data for seismic hazard assessment. natural hazard, 2222, 225-270. galadini f. e messina p. (1993). stratigrafia dei depositi continentali, tettonica ed evoluzione geologica quaternaria dell'alta valle del f. sangro (abruzzo meridionale). boll. soc. geol. it., 111122, 877-892. galadini f., messina p., giaccio b. e sposato a. (2003). early uplift history of the abruzzi apennines (central italy): available geomorphological constraints. quaternary international 110011--110022, 125-135. messina p., moro m. e speranza f. (2001). primi risultati di stratigrafia magnetica su alcune formazioni continentali dell'alta valle dell'aterno (italia centrale). il quaternario, 1144, 167-172. moro m., bosi v., galadini f., galli p., giaccio b., messina p. e sposato a. (2002). analisi paleosismologiche lungo la faglia del m. marine (alta valle dell'aterno): risultati preliminari. il quaternario, 1155,, 267-278. narcisi b. e sposato a. (1989). elementi di cronologia dell’attività vulcanica. in "elementi di tettonica pliocenico-quaternaria ed indizi di sismicità olocenica nell'appennino laziale-abruzzese". guida all'escursione della s. g. i., 89-96. esa grafica. 239 ms. ricevuto il 15 luglio 2003 testo definitivo ricevuto il 23 settembre 2003 ms. received: july 15, 2003 final text received: september 23, 2003 sedimenti e forme quaternari ... imp.carveni-benfatto ll’’eerruuzziioonnee eettnneeaa ddeell 11886655 ((mmoonnttii ssaarrttoorriiuuss)):: aassppeettttii ggeeoommoorrffoollooggiiccii ee iinnqquuaaddrraammeennttoo nneellll’’eevvoolluuzziioonnee ddeell vvuullccaannoo ppiieettrroo ccaarrvveennii11 && ss.. bbeennffaattttoo22 1dipartimento di scienze geologiche dell’università di catania, sezione geologia e geofisica, corso italia 55, 95129 catania, italia. 2geologo, libero professionista, via san marco 91, 95047 paternò, (ct), italia. riassunto: carveni p. & benfatto s., l’eruzione etnea del 1865 (monti sartorius): aspetti geomorfologici e inquadramento nell’evoluzione del vulcano. (it issn 0394 – 3356, 2004). sulla base di una rilettura critica delle relazioni di autori testimoni dell'evento, dell’analisi di aerofotografie e di rilievi geomorfologici di dettaglio, viene ricostruita l’eruzione laterale etnea del 1865, durante la quale si sono formati i monti sartorius. nella zona del vulcano interessata dall’eruzione sono presenti edifici piroclastici preistorici, geneticamente collegati a fratture eruttive con direzione enewsw, con progressiva migrazione verso se delle fratture eruttive. l’eruzione in studio è stata alimentata attraverso due distinte serie di fratture eruttive, una con direzione ene-wsw, concordante con quella delle strutture distensive riconosciute nel settore d’interesse, l’altra con direzioni comprese tra n 10° ÷ 25° w, e coincidenti con quelle delle faglie normali che formano la scarpata ibleo-maltese. la ricaduta balistica dei materiali piroclastici, condizionata dalle condizioni atmosferiche, ha dato luogo ad edifici asimmetrici. l’analisi morfologica mette in evidenza la ripresa dell’attività in corrispondenza di precedenti apparati e una ripresa recente dell’attività da una delle bocche eruttive. abstract: carveni p. & benfatto s., 1865 monti sartorius eruption: morphologic aspects in the frame of mt. etna evolution. (it issn 0394 – 3356, 2004). the eruptive phenomenology and the morphological aspects of 1865, january 28th – june 15th mount etna lateral eruption are described in this paper. mount etna is the largest european active volcano; it is formed by the volcanic products of many eruptive centres. mount etna is located on the margin of the two main structural domains of eastern sicily: the iblean foreland and the apenninesmaghrebian chain; the first belongs to the northern part of the african plate and consists of a mainly carbonate succession of triassic to pleistocene age, with several intercalations of mafic volcanic rocks; the apennines-maghrebian chain consists of several thrust sheets, made up of structural units derived from different palaeogeografic regions. many studies about structural patterns of mount etna identified four tectonic trends: n-s, ene-wsw, ne-sw and nw-se. this eruption occurred along the ne flank of the volcanic edifice; some prehistorical vents were active in this zone: the position and chronology of these cones demonstrate a progressive displacement of eruptive fissures toward se. a trustworthy reconstruction of this etna eruption is based on papers of witnesses, on aerial photo analysis and on geological and geomorphologic surveys. the feeder system of the eruption was characterized by two eruptive fracture systems: the main system, ene-wsw oriented; a cluster of fractures ranging n-s to nnw-sse forms the latter. morphological analysis suggests several volcanic activities at different times; the last is witnessed by undated new vent. parole chiave: etna, eruzione laterale del 1865, morfologia. keywords: 1865 lateral eruption on mount etna volcano (sicily), geomorphology. il quaternario italian journal of quaternary sciences 1177(1), 2004, 41-54 11.. iinnttrroodduuzziioonnee il 29 gennaio 1865 iniziò sull’etna un’eruzione laterale le cui fasi sono state descritte, con diverse lacune temporali causate dalle condizioni atmosferiche, da grassi (1865) e silvestri (1867). la rilettura critica dei documenti bibliografici è stata seguita da un’analisi di fotografie aeree e da un rilievo geologico-geomorfologico di dettaglio, al fine di analizzare la distribuzione delle fratture e delle bocche eruttive, le forme di accumulo dei depositi piroclastici e l’azione morfologica dell’erosione. questa eruzione è già stata oggetto di studio (carveni et al., 1998; 2000): nel presente articolo verranno puntualizzati alcuni aspetti che, per motivi di spazio, non hanno trovato il giusto rilievo nei precedenti. nei primi due articoli sono state distinte tre fasi dell’eruzione, collegate alla fluttuazione del tasso di emissione istantaneo, sono state studiate le morfologie di flusso delle colate, ed è stata riconosciuta l’esistenza di due distinti allineamenti di fratture eruttive. 22.. qquuaaddrroo ggeeoollooggiiccoo--ssttrruuttttuurraallee ddeell-ll’’aarreeaa eettnneeaa l’etna, il vulcano attivo più grande d'europa, è uno stratovulcano risultante dalla sovrapposizione dei prodotti emessi durante gli ultimi 700.000 anni da numerosi apparati eruttivi, poggianti su un substrato in parte alloctono, in parte formato da depositi miocenico-quaternari (romano et al., 1979). l’etna sorge su un’area di debolezza tettonica ubicata all’intersezione di allineamenti tettonici regionali (ogniben et al., 1975), lungo la sutura tra la placca africana e la placca europea, dove la crosta oceanica ionica e la crosta continentale dell’avampaese ibleo si immergono sotto il fronte dell’orogene appenninicomaghrebide (finetti et al., 1996) (fig. 1). l’avampaese ibleo, rappresentante in sicilia orientale il margine della placca africana (burollet et al., 1978), zona considerata stabile verso cui convergono le falde neogeniche dell’orogene appenninicomaghrebide, confina ad oriente con la crosta oceanica 42 p. carveni & s. benfatto del bacino ionico (finetti, 1982) tramite la scarpata ibleo-maltese, la cui origine tettonica è stata riconosciuta, tramite profili sismici, da finetti & morelli (1972); essa è stata originata da un sistema di faglie normali a gradinata, il cui prolungamento verso settentrione interseca il fianco orientale dell’edificio etneo (lo giudice et al., 1982; carbone et al., 1982 a; 1982 b). per casero et al. (1984) essa rappresenta un sistema strutturale distensivo, raccordante il plateau continentale siculomaltese con la piana abissale ionica; la struttura si sarebbe formata in un’unica grande fase tortoniana, con minori riattivazioni posteriormente al deposito degli infrapliocenici trubi; alla scarpata sono connesse a luoghi importanti attività vulcaniche. l’orogene appenninico-maghrebide si è formato in seguito all’accavallamento della catena kabilocalabride sulla catena appenninico-maghrebide (finetti et al., 1996); questa convergenza ha provocato un accorciamento crostale in direzione n-s valutato tra 29 e 33 chilometri (cassinis et al., 1979). recenti fasi tettoniche hanno causato un’elevata distorsione al margine settentrionale della placca africana, a causa della differente velocità con cui avviene la subduzione al di sotto della catena appenninico-maghrebide (van bemmelen, 1969; morelli, 1970; selli & fabbri, 1971; giese & morelli, 1975), e ciò ha determinato uno stiramento crostale che ha dato luogo a fratture con direzione nw-se, ne-sw ed e-w (ghisetti & vezzani, 1982; scandone, 1982); all’intersezione di tali strutture si è formata una zona di debolezza attraverso la quale avviene la risalita di magmi subcrustali (frazzetta & villari, 1981). l’attività eruttiva, inizialmente sottomarina e fissurale, è diventata in seguito subaerea ed a carattere centrale, a causa di un sollevamento regionale, tutt’ora in atto, che ha determinato una variazione nel meccanismo di risalita dei magmi, con conseguente cambiamento del chimismo: si passa infatti da prodotti subalcalini a prodotti più o meno differenziati della serie alcalinosodica emessi da numerosi centri eruttivi e raggruppati in quattro unità vulcano-stratigrafiche: centri alcalini antichi, trifoglietto s.l., mongibello antico e mongibello recente (romano, 1982). sulla base di datazioni radiometriche del rapporto k/ar, gillot et al. (1994) hanno distinto quattro periodi di attività dell’etna: il primo periodo (da 520.0000 ± 40.000 a 270.000 anni fa) è caratterizzato da vulcanismo tholeiitico, con fasi eruttive separate da lunghi periodi di quiescenza; il secondo periodo (da 168.000 ± 8.000 a 100.000 anni fa) è evidenziato da un radicale cambiamento del tipo di attività (strato-vulcani al posto di fessure eruttive) e del chimismo dei prodotti (da sub-alcalini ad alcalini); durante il terzo periodo (tra 80.000 e 60.000 anni fa) si formò un grande complesso vulcanico poligenico (unità del trifoglietto); il quarto periodo (da 35.000 anni fa ad oggi) corrisponde allo sviluppo di un grande strato-vulcano, il mongibello; un’importante fase esplosiva, caratterizzata da eruzioni pliniane e idromagmatiche, permette di suddividere questo periodo in due parti: mongibello antico e mongibello recente. carapezza (1962) per primo cerca di determinare una relazione tra la tettonica regionale e le zone di minore resistenza del vulcano, dalle quali hanno origine le eruzioni; egli riconosce una zona di rift, che attraversa il fianco orientale dell’edificio vulcanico, e lungo la quale si concentra l’attività vulcanica recente. nel primo studio analitico sulle faglie dell’etna (marchesini et al., 1964) sono stati riconosciuti quattro gruppi principali di allineamenti tettonici, con direzioni ns, ene-wsw, ne-sw e nw-se. romano (1970) e rittmann et al. (1973) confermano l’importanza dei trend n-s e ene-wsw. kieffer (1975) riconosce una zona di rift che attraversa la zona sommitale del vulcano da nord a sud, lungo cui si concentrano le eruzioni recenti. frazzetta & romano (1978) identificano due allineamenti come alimentatori preferenziali per le aree con alta probabilità di nuove eruzioni: la principale è compresa tra ne-sw e ene-wsw, la seconda ha direzione nnw-sse. sulla base delle ipotesi di nakamura (1977) e di nakamura et al., (1977), frazzetta & villari (1981) utilizzano gli allineamenti di fratture e coni piroclastici per determinare i campi di stress dell’etna e riconoscono una zona e-w con trascorrenza sinistra e con σ1 ene e σ3 nnw. per lo giudice et al. (1982), invece σ1 ha orientazione nne e σ3 wnw; essi riconoscono nell'area etnea e nelle zone circostanti varie direttrici di faglie: le più importanti hanno direzione n 60° e, n 30° e, n 15° w e n 60° w. kieffer (1983 a; 1983 b) definisce, in base alle numerose fratture collegate alle eruzioni, un “rift di ne”, un rift meridionale e una serie di assi nw-se e ne-sw; le faglie delle due zone di rift e le faglie della zona delle timpe farebbero parte di una serie di faglie normali che interessano la parte orientale del vulcano e del suo substrato; l’intrusione ripetuta di magma provocherebbe uno scivolamento gravitativo della parte orientale del vulcano. l’ipotesi di uno scivolamento gravitativo di una porzione dell’edificio etneo viene ripresa e sviluppata da azzaro et al. (1989 a) e da neri et al. (1991); questi ultimi distinguono sul versante orientale dell’etna un settore settentrionale, caratterizzato da meccanismi di dislocazione distensiva con componenti orizzontali sinistre, ed uno meridionale, distensivo con componenti orizzonfig. 1 ubicazione dell'area studiata. cckkcc) catena kabilocalabride; ccaamm) catena appenninico-maghrebide; ccss) catena sicana; aaii) avampaese ibleo; ee) edificio vulcanico etneo (da finetti et al., 1996); il quadrato grigio indica la zona dell’eruzione del 1865. localization of studied area. cckkcc) kabilo-calabrian chain; ccaamm)) apenninian-maghrebian chain; ccss) sicanian chain; aaii) iblean foreland; ee) mt etna volcano (after finetti et al., 1996); grey square points out the 1865 etna eruption area. tali destre; tali condizioni di instabilità influenzano la risalita dei magmi in questo settore del vulcano, specialmente lungo il trend nnw-sse (ferrucci et al., 1993). borgia et al. (1992), basandosi sui risultati delle analisi di ferrari et al. (1991) sui dicchi affioranti nella valle del bove, teorizzano uno spreading radiale del 43l’eruzione etnea del 1865 ... sub-strato dell'etna verso se. secondo lo giudice & rasà (1992) si tratta invece di movimenti puramente gravitativi, che provocano uno scivolamento verso sse del settore del versante orientale dell’etna delimitato dalla faglia della pernicana, dal “rift di ne” e dalle faglie di mascalucia-trecastagni (fig. 2). fig. 2 ubicazione dell'area interessata dall'eruzione, in rapporto alle più importanti strutture vulcano-tettoniche del versante nordorientale dell'etna: cccc) cratere centrale; ffmmaa) faglia di mascalucia; ffmmoo) faglia di moscarello; ffmmss) faglia macchia – stazzo; ffpp) faglia della pernicana; ffppvvcc) faglia praiola – villa calanna; ffssll) faglia di san leonardello; fftt) faglia di trecastagni; rrnn) faglia della ripa della naca; rrnnee) rift di ne; rrpp) faglia della ripa di piscio. centri abitati e contrade: aarr) acireale; g) giarre; mm) mascalucia; mmaa) monti arsi; ssaa) sant'alfio; ssgg) san giovanni; tt) trecastagni. i cerchi piccoli indicano l'ubicazione di coni avventizi, le aree contrassegnate dai numeri 11886655, 11992288 e 11997711 indicano le zone coperte dalla lava durante le relative eruzioni. location of area interested by 1865 etna eruption in the frame of the main volcanic-tectonic structures of north-eastern flank of mt. etna volcano: cccc) central crater; ffmmaa) mascalucia fault; ffmmoo)) moscarello fault; ffmmss) macchia – stazzo fault; ffpp)) pernicana fault; ffppvvcc) praiola – villa calanna fault; ffssll) san leonardello fault; fftt)) trecastagni fault; rrnn) ripa della naca fault; rrnnee)) ne rift; rrpp) ripa di piscio fault. towns and districts: aarr) acireale; g) giarre; mm) mascalucia; mmaa) monti arsi; ssaa) sant'alfio; ssgg) san giovanni; t) trecastagni. little circles correspond to cinder cones; the areas marked by the numbers 11886655,, 11992288 and 11997711 correspond to zones covered by lava flows during these eruptions. 44 in una serie di articoli viene analizzata la documentazione storica relativa ai terremoti avvenuti sul basso versante orientale etneo negli ultimi due secoli e le conseguenze dei movimenti tettonici sulla morfologia (adorni & carveni, 1993 a; 1993 b; carveni & bella, 1994; bella et al., 1996; carveni et al., 1996; gresta et al., 1997); sulla base dei dati geoelettrici forniti da cassinis et al. (1970), confrontati con le profondità ipocentrali calcolate per alcuni sismi (postpischl, 1985; azzaro et al., 1989 a; 1989 b; bottari et al., 1989), carveni et al. (1997) ipotizzano che gli ipocentri di alcuni terremoti siano localizzati in corrispondenza del passaggio dalle argille azzurre pleistoceniche ai soprastanti prodotti vulcanici. dall’analisi dei differenti sistemi di faglia che nel corso del pleistocene sono stati attivi in calabria meridionale e nella sicilia orientale, e sulla base di informazioni geologico-strutturali e morfologiche di campagna e dell’analisi di sezioni sismiche a mare, monaco & tortorici (1995) e monaco et al. (1995; 1997) distinguono un “sistema acireale – s. alfio” (formato da faglie normali con componente trascorrente destra nnw-sse) e un “sistema di piedimonte” (faglie normali e fratture d’estensione nne-ssw); entrambi i sistemi, che sono associati ad un’estensione wnw-ese, formano scarpate di età suprapleistocenico-olocenica, le quali esercitano un controllo sulla topografia e sul reticolo idrografico. l’edificio vulcanico etneo è caratterizzato da numerosi apparati eruttivi effimeri, molti dei quali sono concentrati lungo tre trend vulcano-tettonici convergenti verso la sommità del vulcano; il primo (“rift di ne”, kieffer, 1983 a; 1983 b) va dai crateri sommitali verso ne (fig. 2: rrnnee), ed è interessato da fessurazioni estensionali con rare faglie normali (borgia et al., 1992); il secondo, ubicato sul fianco meridionale (kieffer, 1983 a; 1983 b) è formato da faglie transdistensive con abbassamento del blocco orientale (borgia et al., 1992; mc guire et al., 1996); il terzo, sul versante occidentale, è caratterizzato da faglie con strike-slip in direzione ne (ferrucci & patanè, 1993). 33.. tteeaattrroo ddeellll’’eerruuzziioonnee l’eruzione in studio è avvenuta in un’area compresa tra importanti elementi morfostrutturali: la scarpata della faglia della pernicana a settentrione, il “rift di ne” a nw, l’orlo settentrionale della valle del bove a meridione e le scarpate delle faglie della ripa della naca e della ripa di piscio a oriente (fig. 3). questo settore dell’edificio vulcanico presenta caratteri tettonici omogenei, rappresentati da stress di fig. 3 a) ubicazione dell’area studiata. b) schema del teatro dell’eruzione: a) faglie; b) fratture eruttive; c) coni piroclastici: 11) monte corvo; 22) monte baracca; 33 e 44) i due monti; 55) monte zappinazzo e monti conconi; 66) monte frumento delle concazze; 77) edificio anonimo a sud-ovest di monte frumento delle concazze; 88) monti sartorius; 99) bocche del 1928; d) orlo della valle del bove; e) alti morfologici: 1100) monte crìsimo; 1111) monte ragamo; 1122) monte chiovazzi; α) colata principale; β) colata di monte crìsimo; γ) colata di monte ragamo; δ) colata di monte chiovazzi. a) location of the studied area. b) scheme of the eruption zone: a) faults; b) eruptive fractures; c) cinder cones: 11) monte corvo; 22) monte baracca; 33 and 44) i due monti; 55) monte zappinazzo and monti conconi; 66) monte frumento delle concazze; 77) no name cinder cone sw from monte frumento delle concazze; 88) monti sartorius; 99) 1928 eruption’s vents; d) valle del bove rim; e) peaks: 1100) monte crìsimo; 1111) monte ragamo; 1122) monte chiovazzi; α) main lava flow; β) monte crìsimo lava flow; γ) monte ragamo lava flow; δ) monte chiovazzi lava flow. p. carveni & s. benfatto 45 tipo transtensivo a componente orizzontale sinistra (neri et al., 1991); l’area è stata interessata in precedenza da eruzioni laterali che evidenziano un progressivo spostamento verso se delle fratture eruttive; dall’analisi della carta geologica del monte etna (romano et al., 1979) risulta che in epoca preistorica si sono formati, progressivamente, monte corvo (fig. 3: 11), monte baracca (fig. 3: 22), i due monti (fig. 3: 33 e 44), monte zappinazzo e i monti conconi (fig. 3: 55), monte frumento delle concazze (fig. 3: 66) e un edificio anonimo a sw di questo (fig. 3: 77). dall’orientamento delle basi ellittiche degli edifici e dalla forma degli orli craterici si desume che tutti questi edifici sono stati alimentati da fratture con direzioni comprese tra ne-sw e ene-wsw. monte corvo (fig. 3: 11), che poggia su lave dei centri eruttivi del leone, si è formato nel periodo di transizione tra l’attività del mongibello antico e del mongibello recente (romano et al., 1979); non gli sono state attribuite colate laviche. monte baracca (fig. 3: 22), la cui attività risale allo stesso periodo, ha emesso una colata lavica attribuita ai centri del mongibello antico e classificata come “difficilmente delimitabile a morfologia superficiale degradata” (romano et al., 1979). la colata di monte baracca è in parte ricoperta dall’edificio meridionale dei due monti (fig. 3: 33), i quali a loro volta hanno emesso lave classificate come “delimitabili a morfologia superficiale ben conservata” (romano et al., 1979). il gruppo dei monti zappinazzo – monti conconi (fig. 3: 55), che poggiano chiaramente sui prodotti vulcanici già descritti, sono classificati come “colate laviche e piroclastiti recenti, prevalentemente non datate” (romano et al., 1979). infine, monte frumento delle concazze (fig. 3: 66), alla cui attività sono attribuibili delle “colate laviche e piroclastiti recenti, prevalentemente non datate” (romano et al., 1979), sulle quali si sono riversate le lave dell’eruzione in oggetto, e che affiorano in alcune zone come dagale, ricopre parzialmente il fianco meridionale di monte zappinazzo. nel 1928 e nel 1971 sono avvenute altre eruzioni che hanno coinvolto lo stesso settore dell’edificio vulcanico, sempre con una progressiva migrazione verso se delle fratture eruttive (fig. 3); nel 1979 si è avuta una nuova emissione dalla frattura eruttiva del 1928. l’eruzione etnea del 1865, quindi, segna la ripresa dell’attività vulcanica in un settore dell’etna già interessato da eruzioni laterali, con progressiva migrazione dell’asse eruttivo verso se, e, come si vedrà in seguito, geneticamente collegate sia a fratture eruttive con direzioni comprese tra ne-sw e ene-wsw, sia a fratture comprese tra nnw-sse e n-s, direzioni già riconosciute come quelle con maggiore probabilità di riattivazione per questo settore del vulcano (romano, 1970; rittmann et al., 1973; frazzetta & romano, 1978). 44.. ccrroonnaaccaa ddeellll’’eerruuzziioonnee i primi sintomi di un incipiente eruzione laterale si manifestarono alle 14,30 del 28 gennaio 1865: furono osservate nuvole di fumo (emissioni di cenere, secondo romano & sturiale, 1982) sollevarsi da monte frumento delle concazze; durante la notte successiva numerose scosse sismiche allarmarono gli abitanti di san giovanni e sant’alfio e della contrada monti arsi, località ubicate lungo il prolungamento settentrionale delle faglie di moscarello, san leonardello e macchia-stazzo (fig. 2), riconosciute come le più attive tra quelle che interessano il versante orientale dell’etna (carveni & bella, 1994). il giorno dopo le scosse aumentarono in frequenza ed intensità, e la più forte, avvenuta intorno alle 23, fu del v grado della scala mercalli nelle già citate località, e si propagò fino ad acireale, distante circa 16 chilometri dal presunto epicentro, ma non fu avvertita a giarre, che ne dista solo sei; dalla direzione di massima propagazione delle onde sismiche, riteniamo che questi terremoti siano da attribuire a faglie con direzione nnwsse, collegabili ad una o più delle faglie nominate. in coincidenza con quest’ultima scossa iniziò l’emissione di lava dal basso fianco nord-orientale di monte frumento delle concazze, mentre l’attività sismica continuò per alcune ore, con intensità decrescente; nel frattempo il cratere centrale non dava luogo ad alcuna attività. nella fase iniziale dell’eruzione si formarono tre fontane di lava lungo una frattura eruttiva, tra le quote 1800 e 1725 (figg. 4 e 5: iiii); porzioni della relativa colata lavica, che raggiunse 2,6 metri di altezza, come è dimostrato dai tronchi carbonizzati lungo il suo percorso (silvestri, 1867), affiorano al di sotto delle coperture piroclastiche dell’edificio aa (figg. 4 e 5: α); questa prima fase si esaurì in poche ore, e le fontane di lava vennero sostituite da tre bocche esplosive (figg. 4 e 5: 11, 22 e 33; fig. 6). il 30 gennaio, mentre le bocche 11, 22 e 33 erano in piena attività stromboliana, a oriente di monte frumento delle concazze si aprì una fenditura di 400 metri di lunghezza con direzione n 20° w (figg. 4 e 5: iiiiii), lungo la quale si attivarono otto fontane di lava (grassi, 1865), le cui piroclastiti hanno formato altrettanti coni di scorie (fig. 5: 44 ÷ 1111). col procedere dell'eruzione le fratture eruttive continuarono a propagarsi verso oriente, provocando la progressiva migrazione sia dei punti di emissione delle colate, sia delle bocche esplosive che man mano li rimpiazzavano: si formarono così di seguito gli edifici piroclastici aa, bb, cc, dd ed ee (figg. 4 e 5) le cui bocche furono quasi tutte attive contemporaneamente tra il 4 e il 5 febbraio. nella tabella 1 è sinteticamente riportata l'attività relativa alle bocche di ciascun edificio, così come si ricava dalle relazioni di grassi (1865) e silvestri (1867): all’iniziale fase parossistica, caratterizzata dall’attività contemporanea di quasi tutti gli apparati eruttivi, seguì una progressiva diminuzione dell’intensità dei fenomeni, con sporadici rinvigorimenti da parte di uno o più apparati. silvestri (1867) distinse già dai primi giorni di febbraio una colata principale (fig. 3: α) e una colata di monte crìsimo (fig. 3: β); la prima raggiunse il punto più basso della sua corsa il 9 febbraio; da questa data fino ai primi di marzo si assistette ad un arretramento del fronte attivo ed un allargamento del settore mediano del campo lavico; nel frattempo venne emessa una terza colata (colata di monte ragamo, fig. 3: γ), che si fermò il 12 febbraio. infine la colata di monte chiovazzi (fig. 3: δ) venne emessa da tre fratture, ubicate rispettival’eruzione etnea del 1865 ... 46 mente alla base settentrionale del cono bb, tra gli edifici dd ed e, alla base nord-orientale dell’edificio ee (fig. 5); essa raggiunse il suo punto più basso il 4 aprile. l’attività eruttiva si estinse del tutto alla metà di giugno. 55.. aassppeettttii mmoorrffoollooggiiccii 55..11.. ii ssiisstteemmii ddii ffrraattttuurree eerruuttttiivvee dalla rilettura critica delle relazioni dei precedenti autori (grassi, 1865; silvestri, 1867), dalla distribuzione fig. 4 e fig. 5 schema della zona dei monti sartorius: le lettere dell'alfabeto latino indicano gli edifici piroclastici formatisi durante l'eruzione in studio (aa ÷ ee) e quelli preesistenti (ss ÷ zz), le lettere dell’alfabeto greco le colate laviche, le cifre romane i tratti delle fratture eruttive descritti nel testo, le cifre arabe le bocche esplosive (cerchio pieno per quelle certe, cerchio vuoto per quelle presunte). monti sartorius zone scheme: latin alphabet letters designate cinder cones formed during 1865 etna eruption (aa ÷ ee) and prehesistent ones (ss ÷ zz); greek alphabet letters designate lava flows; roman numerals designate segments of eruptives fractures; arab numerals indicate explosive vents (full circles correspond to sure ones, empty circles to probable vents). p. carveni & s. benfatto spaziale di fratture, bocche eruttive e accumuli piroclastici, si ricava che l’eruzione in studio è stata alimentata da due distinti sistemi di fratture: il primo (sistema principale di fratture eruttive) è radiale rispetto al condotto centrale dell’etna e ha direzione ene-wsw; il secondo (sistema secondario di fratture eruttive) è formato da fratture con direzioni comprese tra nnw-sse e n-s (carveni et al., 1998; 2000). parte del primo tratto del sistema principale di fratture eruttive (fig. 4: i) è riconoscibile su una fotografia pubblicata da silvestri (1867): sul fianco nord-orientale di monte frumento delle concazze, a partire dalla profonda svasatura dell’orlo craterico, scende una serie di faglie normali con andamento ad “s”; il graben cui danno luogo ha un’ampiezza massima, in corrispondenza dell’orlo craterico, di 50 metri, mentre verso il basso l’ampiezza diminuisce fino a 2 metri in corrispondenza del punto d’inizio dell’emissione; tracce di questo graben sono tuttora riconoscibili sul terreno, malgrado esso sia impostato su piroclastiti: in occasione di forti precipitazioni atmosferiche, infatti, le acque di ruscellamento si incanalano lungo le linee di faglia. secondo quanto riferito da silvestri (1867), la frattura poteva essere seguita dal crinale della valle del bove fino al cratere di monte frumento delle concazze, per una lunghezza complessiva di circa due chilometri e mezzo. il secondo tratto (fig. 4 e 5: iiii), corrispondente al segmento della frattura eruttiva lungo cui si attivarono le prime tre fontane di lava, è compreso tra 1800 e 1725 metri di quota; la frattura è beante ed ispezionabile per un tratto di circa 350 metri e fino ad una profondità massima di 8 metri circa. un’altra frattura dello stesso sistema è evidenziata dall’allineamento delle bocche eruttive nei crateri degli edifici bb, cc e dd (figg. 4 e 5: iivv). ulteriori allineamenti di bocche eruttive e di depositi piroclastici consentono di riconoscere il sistema secondario di fratture eruttive; alcuni suoi elementi, inoltre, sono stati descritti da grassi (1865) e da silvestri (1867). il primo segmento di questo sistema è quello che disloca il tratto i del sistema principale di fratture eruttive, e corrisponde alla prosecuzione verso meridione della frattura eruttiva dei crateri di monte zappinazzo (fig. 4: vv). il secondo corrisponde alla frattura eruttiva che ha alimentato le 8 fontane di lava descritte da grassi (1865) (figg. 4 e 5: iiiiii). il terzo ha alimentato le bocche dei crateri aa11, aa22 e aa33 (figg. 4 e 5: vvii). silvestri (1867) ha descritto due fessure rettilinee, tangenti all’orlo occidentale del cratere dell’edificio bb, le quali emettevano unicamente vapori (figg. 4 e 5: vviiii). infine, alcune morfosculture parallele alle fratture del sistema secondario sono state individuate tramite l’analisi di fotografie aeree: tre di esse sono piccole scarpate rettilinee assimilabili a faglie con blocco orientale ribassato (figg. 4 e 5: vviiiiii, iixx e xx). 55..22.. ggllii eeddiiffiiccii ppiirrooccllaassttiiccii gli accumuli delle piroclastiti emesse nel corso dell’eruzione in esame formano una serie di coni di scorie a forma di scudo, di spatter cones e di edifici troncoconici con crateri sommitali; forme e dimensioni sono state determinate tramite carte topografiche in scala 1:10.000 e l’analisi di aerofotografie; per alcune morfologie non rappresentate cartograficamente a causa delle ridotte dimensioni sono state effettuate misure speditive in campagna. i coni a scudo 11, 22 e 33 sono tre edifici tra loro coalescenti, ubicati sul basso versante nord-orientale di monte frumento delle concazze (fig. 6); nella già citata fotografia (silvestri, 1867) si vede che questi tre edifici preesistevano all’eruzione in studio: si tratta quindi di edifici poligenici, già collegati ad un’attività preistorica dell’edificio suddetto, e riattivatosi nel corso dell’eruzione del 1865. essi hanno forma a scudo con contorno ellittico, 47l’eruzione etnea del 1865 ... tab. 1 sequenza temporale dell’attività delle bocche eruttive. vents activity sequences. ddaattee ddeellllee oosssseerrvvaazziioonnii 28.1 29.1 30.1 31.1 3.2 4.2 5.2 6.2 20.2 26.2 5.3 19.3 25.3 15.4 28.4 6.5 15.5 1 f l e c i 2 f l e e e e 3 f l e e e e 4-11 f l a 1 e e i o a 2 e e e e e ? c c e i o a 3 e e e e e ? c c e i o b e e e c e c v e e e e c e e e c e o d e e e c d d d o i e e e e e v a v a e e v s s legenda: s) scosse sismiche; f l) fontane di lava; e) esplosioni con lancio di scorie e bombe; c) emissione di ceneri; v a) emissione di vapori ad alta pressione; v) emissione tranquilla di vapore; d) detonazioni; i) bocche inattive; o) condotto ostruito. explanation notes: s) earthquakes; f l) lava fountains; e) explosions with cinder and bombs throwing; c) ash emission; v a) high pressure steam issue; v) calm steam issue; d) detonations; i) inactive vent; o) obstructed duct con l’asse maggiore lungo la frattura eruttiva, la quale permette un’analisi della struttura interna degli edifici; dal basso affiora la seguente successione: scorie e lapilli saldati, di colore rossastro; dalla giacitura si evince che provenivano da diversi punti di emissione; lo spessore in affioramento raggiunge i 3 metri; basalto a fessurazione colonnare, con spessore massimo in affioramento di 2 metri; sulle pareti si trovano scorie saldate, presumibilmente relative all’evento eruttivo in studio; scorie e bombe saldate, di colore grigio, con spessore massimo di 4 metri; scorie e bombe saldate, con spessore massimo di 3 metri, relative all’eruzione in oggetto; uno strato discontinuo di cineriti alterate permette di distinguere questo banco dal precedente. in corrispondenza delle bocche eruttive queste ultime piroclastiti raggiungono il massimo spessore. la presenza, al di sotto delle piroclastiti attribuite all’eruzione in studio di altri due livelli di scorie e bombe saldate, cui si intercala una colata basaltica, conferma l’ipotesi di riattivazione della frattura in oggetto. l’esame delle fotografie aeree evidenzia che gli edifici sono ubicati in una depressione di forma trapezoidale, delimitata da scarpate rettilinee, presumibilmente corrispondenti a piani di faglie dirette (figg. 4 e 5: xxii, xxiiii e xxiiiiii), il cui riscontro sul terreno è problematico, a causa delle coperture piroclastiche ed epiclastiche. le dimensioni dei tre edifici sono riportate nella tab. 2; un calcolo approssimativo del volume del materiale eruttato dalle relative bocche durante la fase iniziale dell’eruzione risulterebbe in difetto, in quanto la parte maggiore dei materiali emessi dalle fontane di lava attive il 29 gennaio alimentò la prima colata lavica, e le scorie e bombe relative all’attività esplosiva protrattasi dal 30 gennaio al 4 febbraio ebbero un’ampia zona di dispersione: secondo silvestri (1867) bombe fino a un metro di diametro vennero scagliate a più di 500 metri di distanza, e le pendici del monte frumento delle concazze furono ricoperte da uno strato di scorie e lapilli spesso fino a 15 centimetri. gli spatter cones 44 ÷ 1111 sono 8 collinette dalla cima tondeggiante (fig. 5: 44 ÷ 1111), formatesi il 30 gennaio 1865 (grassi, 1865) per l’accumulo dei materiali emessi da 8 fontane di lava ubicate lungo una frattura eruttiva con direzione n 20° w (figg. 4 e 5: iiiiii); esse in seguito sono state parzialmente ricoperte da piroclastiti emesse dalle bocche dell’edificio aa (fig. 7). nella tabella 2 sono riportati i loro parametri; l’andamento circolare delle loro basi è da attribuire ad una distribuzione delle piroclastiti poco o per nulla condizionata dagli agenti atmosferici, su una superficie quasi orizzontale; anche qui il calcolo del volume emesso risulta in difetto, considerando che parte del materiale diede luogo ad una colata lavica, attualmente sepolta dall’edificio a. 48 fig. 7 il cono di scorie 1100, parzialmente ricoperto (a destra) dalle piroclastiti dell’edificio aa, visto da meridione. spatter cone 1100 from south. its right flank is covered by cinder cone aa pyroclastics. fig. 6 panoramica sui coni di scorie 11, 22 e 33, visti da oriente, dall’orlo occidentale del cratere aa22. panoramic view on 11, 22 and 33 scoria cones, from western rim of aa22 crater. p. carveni & s. benfatto i coni di scorie aa ÷ ee sono edifici troncoconici con crateri sommitali; i loro crateri, esauritasi l’attività vulcanica, hanno subito, a causa degli agenti atmosferici, l’erosione degli orli con accumulo dei materiali all’interno, e conseguente trasformazione da crateri a imbuto con condotto aperto in cavità a forma di conca, in alcuni casi a fondo piatto: dall’iniziale superficie di accumulo delle piroclastiti, sviluppatasi in funzione dell’attività vulcanica e degli agenti meteorologici (che ne condizionavano la traiettoria balistica e la distribuzione), si è passato ad una superficie di erosione a monte – accumulo a valle, funzione degli agenti esogeni; fa eccezione il cratere bb, come verrà descritto più avanti. l'edificio aa (figg. 4 e 5) è un edificio composito, formato da due tronchi di cono coalescenti (fig. 8), allineati in direzione n 10° w, con 2 crateri maggiori ellittici (fig. 5: aa22 e aa33) con asse maggiore orientato nnwsse; sul versante nw del cono settentrionale si apre un cratere (fig. 9) di minori dimensioni (fig. 5: aa11), il cui edificio è stato quasi del tutto sepolto dalle piroclastiti emesse dalle bocche del cratere aa22. le tre cavità crateriche hanno forma di semisfera e sono interessate da fenomeni erosivi, con conseguente arretramento dell'orlo craterico; sul fondo non c'è traccia delle bocche eruttive che, secondo silvestri (1867), erano una nel cratere aa11, tre disposte in direzione nnw-sse nel cratere aa22, e tre, ai vertici di un triangolo equilatero, nel cratere aa33; il fondo dei crateri aa22 e aa33 è allungato in senso nnw-sse, parallelamente alla frattura eruttiva vvii (figg. 4 e 5; tab. 3). la forma ellittica presentata dalla base dal cono aa22 (tab. 3) è da attribuire all’allineamento delle sue tre bocche eruttive lungo la frattura vvii (fig. 5); la non concordanza con la forma dell’orlo craterico può derivare da fenomeni erosivi che hanno aggredito con maggiore vigore la parte più alta dell’edificio conico, provocando un veloce arretramento dell’orlo craterico. l’asse maggiore della base dell’edificio aa33 ha azimut n 82°, il minore n 172°: ciò può essere spiegato con la distribuzione spaziale delle tre bocche eruttive, ai vertici di un triangolo, che danno luogo a due allineamenti: la frattura iivv e la frattura vvii (fig. 5); la forma ellittica dell’orlo craterico è coerente con quella della base dell’edificio. l'edificio bb presenta ben esposti il versante settentrionale (60 metri di dislivello massimo tra l'orlo del cratere e la base dell'edificio) e quello meridionale (55 metri), mentre quello occidentale è coalescente con l'edificio aa e quello orientale con l'edificio cc. l’orlo craterico ha forma ellittica, diametro massimo di 120 metri in direzione n 60° e; l’andamento altimetrico è caratterizzato da un massimo assoluto ad occidente e un massimo relativo a meridione; il punto più basso è a ene, dove il cratere si apre verso l’edificio c. i parametri relativi alla base dell’edificio non sono indicativi (tabella 3), perché condizionati dagli altri edifici coalescenti; gli assi dell’ellisse dell’orlo craterico sono coerenti con la direzione della frattura eruttiva iv (fig. 5). l’erosione della cavità craterica ha messo in evidenza la struttura interna dell’edificio: lungo alcuni tratti delle pareti quasi verticali affiorano bombe e scorie saldate (fig. 10). i materiali erosi dalle pareti e accumulatisi sul fondo del cratere hanno fatto assumere a questo una forma a semisfera; tre deboli depressioni circolari, corrispondenti ad altrettante bocche eruttive, si trovano sul fondo del cratere; una quarta bocca, situata quasi al centro della cavità craterica, con 8 metri di diametro e 3 di profondità, circondata da un anello di scorie e bombe saldate alto tra 50 e 80 centimetri (fig. 11), in contrasto con tutte le altre bocche dei monti sartorius presenta 49 fig. 8 l’edificio aa con i crateri aa22 e aa33, visto da sw (foto di s. surrentino). aa volcanic building, with aa22 and aa33 craters from sw. l’eruzione etnea del 1865 ... tab. 2 principali parametri degli edifici piroclastici minori. main parameter of little pyroclastic buildings aa bb cc 11 85° 125/50 m 3 m 22 65° 110/60 m 4,5 m 33 65° 170/110 m 6 m 44 30 m 10 m 55 25 m 8 m 66 25 m 8 m 77 32 m 10 m 88 20 m 6 m 99 30 m 10 m 1100 25 m 7 m 1111 15 m 4 m aa = azimut dell'asse maggiore; bb = diametro massimo/minimo della base dell'edificio; cc = altezza dell'edificio. aa = maximum axis azimuth; bb = length of base maximum/minimum axis; cc = building height. un aspetto molto più “giovane”, e testimonia, a nostro avviso, una ripresa dell’attività eruttiva sfuggita all’osservazione per la sua brevità e/o per il momento in cui è avvenuta; la piccola quantità di materiale emesso (circa 20 metri cubi) suggerisce una singola debole esplosione, avvenuta in un periodo in cui il cratere aveva già raggiunto la fase morfologica a semisfera dal fondo piatto. il fatto che una piccola eruzione dell’etna possa essere passata inosservata in tempi recenti non deve destare alcuna meraviglia: la lontananza dalle zone abitate e soprattutto le condizioni atmosferiche possono aver benissimo impedito l’osservazione di un fenomeno di brevissima durata; d’altro canto l’esplosione verificatasi al cratere sub-terminale di se il 5 gennaio 1990, considerata il maggiore evento esplosivo verificatosi sull’etna nel corso degli ultimi due secoli, a causa delle pessime condizioni meteorologiche non è stata osservata da alcun testimone, e la ricostruzione dell’evento è stata effettuata sulla base della distribuzione delle piroclastiti (carveni et al., 1994). un piccolo affioramento di cineriti saldate, ubicato lungo la parte occidentale dell'orlo craterico, rappresenta i resti dell'originario versante interno, e dà la misura dell'intensità con cui ha agito l'erosione (fig. 12). alla base settentrionale dell'edificio bb si trova uno dei punti di emissione della colata 50 fig. 10 interno del cratere del cono bb visto dal culmine dell’orlo meridionale. panoramic internal view of volcanic building bb crater, from its southern crater rim. fig. 9 il cratere aa11 visto da settentrione, dall’alto dei resti di un preesistente edificio (figg. 4 e 5: s). aa11 crater seen from prehesistent building ss (figg. 4 and 5). p. carveni & s. benfatto tab. 3 principali parametri degli edifici piroclastici maggiori. main parameter of big pyroclastic buildings. 11 22 33 44 55 66 77 88 99 1100 1111 1122 1133 aa11 12 123 10 33 146 292 85 aa22 120 172 110 82 95 82 70 172 65 82 50 262 180 aa33 130 82 100 172 95 80 70 172 60 53 40 154 180 bb 115 242 90 358 120 58 100 148 70 245 45 60 30 cc 35 74 30 164 25 330 20 60 60 dd 125 230 55 50 60 138 55 60 35 156 25 50 90 ee 220 105 75 285 125 25 120 115 60 133 11 = diametro massimo della base dell'edificio, in metri; 22 = azimut del diametro massimo della base dell'edificio; 33 = diametro minimo della base dell'edificio, in metri; 44 = azimut del diametro minimo della base dell'edificio; 55 = diametro massimo dell'orlo del cratere, in metri; 66 = azimut del diametro massimo dell'orlo del cratere; 77 = diametro minimo dell'orlo del cratere, in metri; 88 = azimut del diametro minimo dell'orlo del cratere; 99 = altezza massima dell'orlo del cratere, rispetto al preesistente piano di campagna, in metri; 1100 = azimut del punto di massima altezza dell'orlo del cratere, rispetto al centro del cratere; 1111 = altezza minima dell'orlo del cratere, rispetto al preesistente piano di campagna, in metri; 1122 = azimut del punto di minima altezza dell'orlo del cratere, rispetto al centro del cratere; 1133 = azimut della congiungente due selle lungo gli orli craterici. 11 = length of base maximum axis, m; 22 = azimuth of base maximum axis; 33 = length of base minimum axis, m; 44 = azimuth of base minimum axis; 55 = maximum diameter of the crater edge, m; 66 = azimuth of maximum diameter of the crater edge; 77 = minimum diameter of the crater edge, m; 88 = azimuth of minimum diameter of the crater edge; 99 = maximum height of the crater edge, in comparison to the pre-existing ground level; 1100 = azimuth of the point of the maximum height of the crater edge, in comparison to the centre of the crater; 1111 = minimum height of the crater edge, in comparison to the pre-existing ground level; 1122 = azimuth of the point of the minimum height of the crater edge, in comparison to the centre of the crater; 1133 = azimuth of aligned crater edge depressions. di monte chiovazzi. il cono piroclastico cc (figg. 4 e 5) ha sviluppo massimo di 25 metri di altezza lungo il fianco settentrionale, mentre gli altri versanti sono coalescenti con gli edifici limitrofi; esso presenta tracce di tre piccoli crateri, interessati da fenomeni erosivi. con sviluppo altimetrico massimo di 40 metri e diametro di base di 175, il cono dd ha un cratere del diametro di 50 metri, al cui interno sono state attive quattro bocche eruttive, irregolarmente distribuite (silvestri, 1867). il profilo dell’orlo craterico presenta una forte asimmetria, con due culminazioni, la più alta a sse, l’altra a settentrione; l’irregolarità nella distribuzione delle piroclastiti è stata causata dai forti venti che soffiarono dal quadrante settentrionale nella fase iniziale dell’eruzione, e dal quadrante meridionale alla fine, condizionando la ricaduta e l’accumulo dei piroclasti. il cratere presenta forma a semisfera, senza alcuna traccia che permetta di ubicare oggi le bocche descritte da silvestri (1867). il cono piroclastico ee (figg. 4 e 5) presenta una forma fortemente asimmetrica: la base ha un diametro massimo di 400 metri sviluppato in direzione e-w; alla sommità si riconoscono due archi di orli craterici con diametro di 100 metri e tre di minori dimensioni, allineati in direzione ene-wsw; il versante rivolto a occidente è alto meno di 10 metri, mentre quello di ese ha un dislivello di 80 metri e una lunghezza di 275 metri. questa forte asimmetria è da attribuire sia alla ricaduta balistica delle piroclastiti condizionata dalle condizioni meteorologiche, sia alla morfologia degli edifici preesistenti, in parte distrutti dalle esplosioni, in parte ricoperti dai nuovi materiali piroclastici. l’intero edificio è interessato da profondi fenomeni erosivi, con riempimento delle cavità ed arretramento degli orli craterici. 66.. tteennttaattiivvoo ddii rriiccoossttrruuzziioonnee ddeellllaa mmoorrffoollooggiiaa pprreeeessiisstteennttee in mancanza di carte topografiche precedenti al 1865, la ricostruzione della morfologia preesistente all’eruzione può essere tentata sulla base dello studio delle fotografie aeree e degli scarsi documenti fotografici dell’epoca. un primo documento è la già citata fotografia pubblicata da silvestri (1867): gli edifici 11, 22 e 33 vi appaiono ricoperti da un rado bosco di pini, molti dei quali furono carbonizzati durante l’eruzione; se ne ricava che si tratta di edifici poligenici, collegati ad una fase di attività non datata di monte frumento delle concazze. a settentrione del cratere aa11 si trova una collina (figg. 4 e 5: ss) la cui sommità sovrasta di circa sei metri l’orlo del cratere suddetto; si tratta dei resti di un precedente edificio che si sviluppa per circa 120 metri verso settentrione, e le cui pendici meridionali sono state in parte smantellate dalle esplosioni, in parte ricoperte dalle piroclastiti emesse dalle bocche del cratere aa22. a meridione degli edifici bb, cc e dd affiorano i resti discontinui di tre orli craterici, relativi ad un 51 fig. 12 cineriti rappresentanti l’antico pavimento interno del cratere dell’edificio bb, in corrispondenza dell’orlo occidentale del cratere (m 1760). old crater pavement of volcanic building bb, near western crater rim (m 1760). fig. 11 bocca nuova” nel cratere dell’edificio bb,, vista dall’orlo sud-occidentale del cratere. new vent in volcanic building bb crater, seen from south-western crater rim. l’eruzione etnea del 1865 ... basso edificio quasi completamente ricoperto (figg. 4 e 5: tt, uu e ww). la colata γ è fuoriuscita da una bocca ubicata alla base meridionale del cratere uu (figg. 4 e 5). la forte asimmetria presentata dall’edificio ee è dovuta all’esistenza sotto il suo fianco orientale di un precedente edificio; altri due piccoli edifici allungati in senso e-w affiorano ai suoi piedi (fig. 13; figg. 4 e 5: yy e zz). 77.. ddiissccuussssiioonnee ddeeii ddaattii ee ccoonncclluussiioonnii il versante nord-orientale dell’edificio vulcanico etneo, sul quale si è verificata l’eruzione del 1865, è caratterizzato da faglie transtensive ne-sw e enewsw, con componente sinistra (neri et al., 1991), da alcuni attribuite a movimenti gravitazionali (borgia et al., 1992; lo giudice & rasà, 1992; mcguire et al., 1996), probabilmente agevolati dalle argille pleistoceniche del basamento etneo (carveni & bella, 1994; gresta et al., 1997; carveni et al., 1997). l’eruzione etnea del 1865 è una classica eruzione laterale (sensu rittmann, 1967); contrariamente però a quanto viene in genere segnalato in occasione di simili eruzioni dell’etna, dalle testimonianze dei precedenti autori non risulta che essa sia stata preceduta a breve distanza di tempo da una risalita magmatica lungo il condotto centrale: la precedente attività verificatasi al cratere centrale consistette nelle esplosioni del 7 e 8 luglio 1863 (grassi, 1865). la mancanza di attività al cratere centrale fa quindi supporre che il magma, senza raggiungere la parte sommitale del condotto centrale, si sia insinuato in una frattura radiale, o che la risalita magmatica sia avvenuta direttamente lungo un condotto secondario, indipendente, almeno in parte, da quello centrale. i sismi premonitori dell’eruzione, avvertiti prevalentemente nella zona compresa tra i monti arsi e i paesi di san giovanni e sant’alfio, sono da attribuire, a nostro avviso, a movimenti del tratto più settentrionale della faglia di moscarello e/o della faglia macchia stazzo (carveni & bella, 1994); il sisma concomitante all’inizio dell’eruzione, avvertito negli stessi luoghi e propagatosi fino ad acireale, ma non a giarre e stazzo, conferma questa ipotesi. questa eruzione segna la ripresa dell’attività vulcanica in un settore dell’etna già interessato da eruzioni preistoriche, con progressivo spostamento verso se delle fratture eruttive; posteriormente al 1865 altre eruzioni sono avvenute nello stesso settore, sempre con spostamento verso se delle fratture di alimentazione (1928 e 1971). dalla distribuzione delle fratture eruttive, delle bocche e dei relativi depositi piroclastici, si evince che l’intrusione magmatica, nell’avanzare lungo la frattura radiale, che in superficie dava luogo al sistema principale di fratture eruttive, man mano che incontrava le fratture del sistema nnw-sse, risaliva anche attraverso queste. il primo sistema è parallelo alle strutture distensive riconosciute nel settore d’interesse (neri et al., 1991), e in special modo alle scarpate delle faglie della ripa della naca e della ripa di piscio. il secondo sistema è evidenziato da: l’allineamento delle fontane di lava (fig. 5: 44 ÷ 1111); l’allineamento delle bocche dei crateri aa11, aa22 e aa33 (figg. 4 e 5); l’analisi delle fotografie aeree che hanno messo in evidenza una serie di allineamenti morfologici con direzione nnw-sse, corrispondenti a faglie normali con labbro orientale ribassato; la testimonianza di silvestri (1867), che descrive fessure rettilinee le quali emettevano esclusivamente vapori (fig. 4 e 5: vviiii). questa serie di allineamenti risulta parallela alle faglie della zona delle timpe, le quali rappresentano, secondo lo giudice et al. (1982) il segmento più settentrionale della scarpata ibleo-maltese; lanzafame & bousquet (1997) attribuiscono un’importanza regionale a questa serie di faglie, che formano una delle più importanti strutture del mediterraneo centrale, il “sistema di faglie eoliano-maltese”. non sempre l’analisi delle caratteristiche morfologiche dei singoli coni fornisce dati inconfutabili per il riconoscimento delle fratture lungo cui è risalito il magma: infatti, mentre l’allineamento delle bocche 11 – 33 (fig. 4), l’allineamento degli spatter cone 44 1111 e l’allineamento dei crateri aa11 aa33 individuano senza ombra di dubbio fratture di alimentazione, le profonde svasature degli orli craterici degli edifici bb, dd ed ee non sono state causate da fenomeni di breaching (sensu tibaldi, 1995). inoltre si è riconosciuto che la morfologia dei coni piroclastici è stata influenzata prevalentemente dalle condizioni atmosferiche: a causa dei forti venti settentrionali che soffiarono per buona parte del mese di febbraio 1865 (silvestri, 1867), la ricaduta balistica delle 52 fig. 13 orlo craterico di un edificio preesistente all’eruzione (figg. 4 e 5: yy), sepolto in parte dall’edificio ee, visto da meridione. crater rim of volcanic building (figg. 4 e 5: yy) partially buried during 1865 eruption by buildind ee pyroclastics, seen from south. p. carveni & s. benfatto piroclastiti provocava una crescita asimmetrica degli edifici. infine, dalla ricostruzione della morfologia preesistente, risulta che i monti sartorius poggiano su un gruppo di edifici antecedenti, verosimilmente alimentati, almeno in parte, dalle stesse fratture eruttive. i risultati conseguiti portano a concludere, contrariamente a quanto affermato da nakamura (1977), che non sempre un vulcano poligenico è alimentato esclusivamente attraverso un condotto centrale: lo studio dell’eruzione etnea del 1865 dimostra inoltre che una risalita magmatica può avvenire attraverso fratture che hanno già dato luogo a precedenti eruzioni. infine, avendo constatato che i monti sartorius fanno parte di un sistema eruttivo poligenico, non si può escludere il verificarsi di nuove risalite magmatiche che diano luogo a ulteriori eruzioni. studio effettuato con i fondi del m.u.r.s.t., nell'ambito della ricerca "morfodinamica di zone vulcaniche e/o sismicamente attive", responsabile p. carveni. rriinnggrraazziiaammeennttii ringraziamo gli anonimi referees per gli utili e costruttivi consigli. rriiffeerriimmeennttii bbiibblliiooggrraaffiiccii adorni g. & carveni p. 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(1969) origin of the western mediterranean sea. verh. k. -ned. geol. mijnbouwkd. genoot., geol. ser., 2266, 13-52. 54 ms. ricevuto il 1° luglio 2003 testo definitivo ricevuto il 20 gennaio 2004 ms. received: july 1, 2003 final text received: genuary 20, 2004 p. carveni & s. benfatto impaginato panizza rreeppoorrtt oonn ““ggllaacciiaall”” ffoorrmmss oobbsseerrvveedd oonn aammbbaa aarraaddaamm mmoouunnttaaiinn ((nnoorrtthheerrnn eetthhiiooppiiaa)) mmaarriioo ppaanniizzzzaa dipartimento di scienze della terra – università di modena e reggio emilia (italy) abstract some geomorphologic characteristics observed on amba aradam mountain (tigray region, northern ethiopia) at altitudes of about 2500 to 2780 m a.s.l. and latitude of about 13°30’ n, are described. these features might be ascribed to glacial modeling: cirques, roches moutonnées, glacial shoulders, moraine deposits and moraine arc and palustrine deposit due to moraine barrage. this framework is strongly in contrast with the fact that in ethiopia the presence of glacial cirques and moraines was reported only in mountain areas at altitudes exceeding 4000 m a.s.l. an alternative assumption is that all these features might constitute a very singular case of “geomorphologic convergence”, that is, landforms that have the same shape and appearance but different genesis. riassunto relazione su forme “glaciali” osservate sul monte amba aradam (etiopia settentrionale). vengono segnalate alcune caratteristiche geomorfologiche sul monte amba aradam (regione del tigrai, nord ethiopia) a quote fra circa 2500 e 2780 m .s.l.m. ed a una latitudine di circa 30°30’ n, che potrebbero far pensare a un modellamento glaciale: circhi, rocce montonate, spalle glaciali, depositi e arco morenici, deposito palustre di sbarramento morenico. questo quadro risulta in contrasto col fatto che in ethiopia la presenza di circhi e morene glaciali sono state segnalati soltanto a quote superiori ai 4000 m s.l.m. un'ipotesi alternativa è che ci si trovi di fronte a un caso molto singolare di “convergenza geomorfologica”, cioè di forme del rilievo che hanno la stessa forma, ma che sono il risultato di processi morfogenetici differenti. keywords: quaternary glaciation, ethiopia, glacial morphology, geomorphological convergence parole chiave: glaciazione quaternaria, etiopia, morfologia glaciale, convergenza geomorfologica. il quaternario italian journal of quaternary sciences 1155(2), 2002, 275-278 during the iag international symposium on “climate changes, active tectonics and related geomorphic effects in high mountain belts and plateaux”, held in ethiopia in december 2002, and, in particular, during an excursion to amba aradam mountain, i had the opportunity to observe some very interesting geomorphologic features which are here described. the area surveyed is located sw of makalè, in the tigray region, in northern ethiopia (fig. 1), at an altitude of 2500 to 2780 m a.s.l. and an latitude of about 13°30’ n. it corresponds to an e-w stretching valley, whose head is formed by two small tributary valleys with a ne to sw arrangement. from the geologic standpoint, it is made up of a silicoclastic sandstone sequence of continental facies with quartz conglomerate, shaly and laterite levels, known as “amba aradam formation” (shumburo, 1968; beyth, 1972; dramis, coltorti and pieruccini, 2002), also known as “upper sandstone” (merla and minucci, 1938; mohr, 1962). the age of this formation is ascribable to the cretaceous (see: dramis, coltorti and pieruccini, 2002; nyssen et al., 2002). from the structural viewpoint, the valley’s lower portion seems to be affected by an e-w oriented tectonic line which might have conditioned the original modelling. this tectonic feature does not seem to be linked to the main fault systems described by arkyn et al. (1971) and by beyth, (1972), which are nnw-sse and nne-ssw oriented (dramis, coltorti and pieruccini, 2002). starting from the double head of the valley, the geomorphologic features are as follows (fig. 1). the head of the little northern valley (1a in the geomorphologic sketch of fig. 1) is modeled within a semi-circular cavity with high and steep flanks, partially affected by rock falls which form debris accumulation at the foot of the rocky slopes. also the head of the little ne valley (1b in the geomorphological sketch of fig. 1) has a similar form, although it is not as clearly defined and looks more degraded by erosion and accumulation processes. immediately downstream of the confluence of the two small valleys, a debris deposit is found (fig. 2 and point 2 in the geomorphological sketch of fig. 1), made up of lithologically homogeneous elements (from the amba aradam formation), though with quite a varied grain-size distribution (from blocks to sand and silt). these elements are mixed, non stratified or smoothed, with no apparent signs of friction. on the flanks of the main valley some sandstone outcrops appear to have been modeled in the form of convex and smoothed surfaces, with traces of sub-horizontal grooves which subsequently were partially sectioned by rock shattering processes (fig. 3 and points 3 in the geomorphological sketch of fig. 1). on the floor of the main valley a palustrine deposit is found (fig. 4a and point 4 in the geomorphological 276 m. panizza fig 1 geomorphologic sketch of the amba aradam south-western slope and location of area surveyed. legend: 1 head of small valleys; 2 –debris deposit; 3 – rocks modeled in form of convex, worn smooth surfaces; 4 – palustrine deposits; 5 – debris deposits (5b: diamicton). schizzo geomorfologico del versante a sud-ovest dell’amba aradam e ubicazione dell'area studiata. legenda: 1 – testata di vallecole; 2 – deposito detritico; 3 – roccia modellata in superfici convesse e levigate, con tracce di scanellature; 4 – deposito palustre; 5 – depositi detritici (5b: diamicton). fig. 2 debris deposit at the confluence of the two small valleys. deposito detritico alla confluenza delle due vallecole sketch of fig. 1 ); its origin is evidently due to the damming of the valley by debris accumulation. two detrital bodies developed on the two sides of the valley (fig. 4), one facing south (b) and the other north (c), appear to be responsible for the valley damming and the afore mentioned palustrine deposit. on the whole these two deposits make up an arc-shaped form of varying clarity; the right-hand side deposit (b in fig. 4 and point 5a in the geomorphological sketch of fig. 1) has been partially terraced by anthropogenetic processes. from the grain-size viewpoint, they are both made up of very heterogeneous materials – up to boulders of about ten cubic meters in volume – resulting from the amba aradam formation. 277report on “glacial” forms ... fig. 3 arenaceous rocks modeled in the form of convex, worn smooth surfaces. rocce arenacee modellate in superfici convesse e levigate fig. 4 palustrine deposits (a) and debris accumulations (b and c); the former (b) have been partially modeled as terraces by anthropogenetic processes. deposito palustre (a) e accumuli detritici affacciantisi (b e c), dei quali il primo (b) parzialmente modellato a terrazzo da processi di antropizzione. fig. 5 diamicton from deposit 5b of the geomorphological sketch of fig. 1. diamicton del deposito 5b dello schizzo geomorfologico della fig. 1. 278 outcrop of the detrital body (fig. 5) (c in fig.4 and 5b in the geomorphological sketch of fig. 1): this is a diamicton-type deposit, that is unsorted with sand and coarse particles dispersed through a mud matrix. it is not stratified and some elements show a certain degree of smoothing. the genetic picture of the area points to glacial modeling. there are very evident indications of this; in fact, from top to bottom, the six geomorphologic units previously described seem to be related respectively to: glacial cirques (points 1 in the geomorphological sketch of fig. 1), moraine deposit from glacial confluence (fig. 2 and point 2 in the geomorphological sketch of fig. 1), roches moutonnées (fig. 3 and points 3 in the geomorphological sketch of fig. 1), moraine barrage pond (fig. 4a and point 4 in the geomorphological sketch of fig. 1 ), small moraine arc (b and c in fig. 4 and points 5a and 5b in the geomorphological sketch of fig. 1) and lateral and frontal moraine deposits (b and c in fig. 4 and points 5a and 5b in the geomorphological sketch of fig. 1). this framework seems to be completed by the presence of less inclined portions of slope, similar to the so called “glacial shoulders”. this picture, though, is in contrast with the fact that in ethiopia the presence of glacial cirques and moraines was reported only in mountain areas at much higher elevations (mts. simien, 4620 m a.s.l.; arsi, 4180 m; bale, 4357 m) (nyssen et al., 2002). some authors, such as nilsson (1940) and hovermann (1954), described glacial traces found at lower altitudes, but subsequent researchers (semmel, 1963; potter, 1976; hastenrath, 1977; messerli and rognon, 1980) refused this hypothesis with different arguments (nyssen et al., 2002). certainly the conformation of this e-w stretching narrow and deep valley, sheltered from the wind, could have favored the persistence of snow and ice during a cold pleistocene period. this possibility, though, needs to be further investigated by means of particularly detailed geomorphologic surveys, correlations with other similar traces in other parts of africa placed at the same latitude, and a precise reconstruction of the climatic conditions (temperature, precipitation and wind regimes etc.) existing in the tigray during the pleistocene. as an alternative hypothesis, all these features might constitute a very singular case of “geomorphologic convergence”, that is, landforms that have the same shape and appearance but different genesis. in this case, the area would be a very good educational example to alert the onlooker to simplistic deductions based mainly on exterior appearances, that is, on prevalently descriptive characteristics (panizza, 1996). aacckknnoowwlleeddggeemmeennttss i wish to thank prof. f. dramis (university of roma tre) and dr. j. nyssen (university of makalè) for the useful exchanges of ideas mainly in the field and for the bibliographic informations. rreeffeerreenncceess arkin y., beyth m., dow d.b., levitte m., temesgen h. and hailu t., 1971. geological map of mekelle sheet nd 37-11 tigre province. min. mines, energy and water res., geol. survey ethiopia, addis ababa. beyth m., 1972. paleozoic-mesozoic sedimentary basin of mekelle outlier. northern ethiopia. amer. ass. petrol. geol. bull., 56, 12, 2426-2439. dramis f., coltorti m. and pieruccini p., 2002. geological and geomorphological framework of the excursion area. iag international symposium, addis ababa, december 2002, 1-12. hastenrath, s., 1977. pleistocene mountain glaciation in ethiopia. j. glaciol. [cambridge], 18/79: 309-313. hövermann, j., 1954. über die höhenlage der schneegrenze in äthiopien und ihre schwankungen in historischer zeit. nachr. akad. wiss. göttingen, 6: 111-137. merla g. and minucci e., 1938. missione geologica nel tigrai. vol. 1 “la serie dei terreni”, rendic. reale accad. italia, centro studi africa orient. ital., 3, 362 pp. mohr p.a., 1962. the geology of ethiopia. addis ababa university press, 268 pp. messerli, b. and rognon, p., 1980. the saharan and east african uplands during the quaternary. in: williams m., faure h. (eds.): 87-132. nilsson, e., 1940. ancient changes of climate in british east africa and abyssinia. a study of ancient lakes and glaciers. geogr. ann., 22: 1-79. nyssen j., poesen j., moeyersons j., deckers j., mitiku h. and lang a., 2002. quaternary glaciations in the ethiopian mountains. earth sc. rev., in press. panizza m., 1996. environmental geomorphology. elsevier, amsterdam, 268 pp. potter, e., 1976. pleistocene glaciation in ethiopia; new evidence. journal of glaciology, 17 (75): 148-150. shumburo m.m., 1968. the amba aradam formation (formely the upper sandstone). mobil petroleum ethiopia inc., unpub. semmel, a., 1963. quartärgeologische untersuchungen im hochland von nordwest-aethiopien. z. dtsch. geol. gesellsch., 115 (2-3): 882. ms. ricevuto il 20 gennaio 2003 testo definitivo ricevuto il 4 febbraio 2003 ms. received: genuary 20, 2003 final text received: february 4, 2003 m. panizza impaginato galli aannaalliissii aarrcchheeoossiissmmoollooggiicchhee nneell ssaannttuuaarriioo ddii eerrccoollee ddii ccaammppoocchhiiaarroo ((mmaatteessee)).. eevviiddeennzzee ddii uunn tteerrrreemmoottoo ddiissttrruuttttiivvoo ssccoonnoosscciiuuttoo eedd iimmpplliiccaazziioonnii ssiissmmootteettttoonniicchhee ppaaoolloo ggaallllii11,, ffaabbrriizziioo ggaallaaddiinnii22,, sstteeffaanniiaa ccaappiinnii33 1dipartimento della protezione civile servizio sismico nazionale, via curtatone 3, 00185 roma paolo.galli@serviziosismico.it 2cnr, istituto di geologia ambientale e geingegneria, sez. roma “tor vergata”, via del fosso del cavaliere, 00133, roma f.galadini@igag.cnr.it 3soprintendenza archeologica e per i b.a.a.a.s. di campobasso riassunto analisi archeosismologiche condotte negli scavi del santuario di ercole di campochiaro hanno consentito l’individuazione di più eventi deformativi a carico delle strutture di pertinenza del tempio sannita (iv sec. a.c-v d.c.). lo scavo di una trincea paleosismologica a ridosso delle strutture deformate ha evidenziato, inoltre, la presenza di una zona di taglio nel substrato ghiaioso, responsabile della dislocazione delle murature, dei pavimenti e della cinta in opera poligonale del santuario. i caratteri della deformazione e l’età delle strutture edilizie interessate testimoniano l’occorrenza di un primo evento di fagliazione nel iii sec. a.c. (relativo ad un terremoto sconosciuto ai cataloghi), cui sono seguiti altri eventi, probabilmente riferibili ai terremoti del 1456 e 1805. il sito è ubicato a ridosso della struttura bordiera settentrionale del massiccio del matese (faglie del m.te patalecchia-bojano-campochiaro), alla quale vengono quindi ascritte le dislocazioni rilevate nel santuario. l’attività di questo sistema di faglie, già noto in parte alla letteratura, è caratterizzato da un elevato slip-rate (0.9 mm/yr) e da tempi di ritorno che non sembrano seguire la periodicità supposta per altre strutture appenniniche. abstract archaeoseismological analyses in the hercules’s sanctuary of campochiaro (matese, central-southern apennine, italy). evidence of an unknown disruptive earthquake and seismotectonic implication. starting from the 6th cent. bc, a vast region of central-southern italy (samnium) was inhabited and dominated by the daring nation of samnites. between the 4th and 3rd cent. bc samnites and romans disputed for the hegemony of central italy, but in 290 bc the former was finally subdued by the latter. samnites raised many important sanctuaries in their land, also after the roman conquest, which remained in use until the decadence of the empire. the sanctuary of hercules near campochiaro is one of these; it was built in the 4th cent. bc, being frequented until the 4th-5th cent. ad (fig. 10). it is located close to the campochiaro fault, a roughly e-w strand of the n-matese massif structure, which borders and controls the formerlacustrine bojano basin (figg. 1, 7-8). archaeoseismological analyses performed within the sanctuary area, supported by paleoseismological trenching (figg. 11-12), geomorphological and geological surveys, allowed the identification of surface faulting of the archeological relics. buildings of the primitive phase have been displaced by a first event in the middle of the 3rd cent. bc (figg. 9, 13-15), whereas the following structures (built up over the faulted ruins of the former) show a subsequent offset, which we relate to the cumulated motion of the m=6.5~7 earthquakes of 1456 and 1805 (although we do not exclude other unknown high middle age events or the 346 ad earthquake). while the 3rd cent. bc earthquake is unknown to the italian historical catalogues, the 1456 and 1805 events are well characterized in terms of intensity datapoint distribution (figg. 5-6), and could both be related to the n-matese massif seismogenetic structure (faults of mt. patalecchia-bojano-campochiaro; fig. 1). according to our interpretation, the seismogenetic behaviour of the nmatese massif structure is rather complex, and does not follow the recurrence interval showed by other apenninic faults (2000±500 yr; see galadini and galli, 2000); on the other hand, its slip-rate (0.9 mm/yr) would be one of the highest in italy. these results suggest that the use of a poisson approach (which requires stationarity in earthquake occurrence) in seismic hazard evaluation studies could be misleading in this sector of the apenninic chain. parole chiave: archeosismologia, paleosismologia, terremoto, sismotettonica, appennino meridionale keywords: archaeoseismology, paleoseismology, earthquake, seismotectonics, southern apennine il quaternario italian journal of quaternary sciences 1155(2), 2002, 155-167 iinnttrroodduuzziioonnee la piana di bojano, da millenni crocevia di popoli e di culture, è una delle aree a più elevata sismicità della penisola italiana. tutte le civiltà che hanno eretto i propri insediamenti nella piana, prima o poi, hanno dovuto confrontarsi con la potenza distruttrice dei terremoti che si originano alle falde settentrionali del matese e con i forti risentimenti degli eventi provenienti dalle aree contermini. la sismicità della regione è in parte nota ai repertori sismologici nazionali (postpischl, 1985; camassi e stucchi, 1997; boschi et al., 1995; gruppo di lavoro cpti, 1999). questi cataloghi, raccogliendo criticamente l’imponente messe di dati, notizie e relazioni sui terremoti storici italiani (retaggio di una tradizione pluricentenaria precipuamente italiana nel campo della sismologia storica), mentre offrono una visione completa della storia sismica di ciascuna regione per quanto attiene agli ultimi secoli (almeno per i terremoti più forti), sono lacunosi ed incerti mano a mano che si proceda a ritroso nel tempo e/o si considerino gli eventi di più bassa energia (si veda stucchi e albini, 2000). ecco dunque che lo studio attraverso una finestra aperta su un passato non coperto interamente dalle fonti letterarie, quale un sito archeologico “in scavo” come quello del santuario di ercole a campochiaro, supplisce ed in parte colma gli hiatus conoscitivi della sismicità storica “convenzionale”. il riconoscimento degli effetti cosismici su vestigia archeologiche consente, 156 p. galli, f. galandini & s. capini infatti, l’individuazione ed una possibile parametrizzazione del terremoto responsabile (p.e., in termini di intensità, data e localizzazione epicentrale), permettendo quindi di arricchire e correggere il catalogo sismico, estendendolo indietro nel tempo. questo è tanto vero quanto detti effetti non siano relativi al solo scuotimento, il cui risultato, se non contestualizzato arealmente e storicamente (galadini and galli, 1999a; galadini et al., 2001; galadini e galli, 2001), non è talvolta dissimile dai dissesti indotti da altre cause (quali vetustà, eventi bellici, frane, alluvioni), ma quanto legati geometricamente alla dislocazione superficiale della faglia mobilizzata col terremoto (galli, 1999; galli and galadini, 2001). nel seguito, a valle di una sintesi del quadro sismotettonico della piana di bojano, verranno riportati i risultati preliminari delle analisi condotte nel santuario di ercole e, in particolare, quelli riguardanti la fagliazione superficiale che ha coinvolto le murature nel sito. i dati raccolti comportano una riflessione sul comportamento della struttura sismogenetica di bojano e sui limiti degli approcci convenzionali negli studi di pericolosità sismica. qquuaaddrroo ggeeoollooggiiccoo ee ssiissmmootteettttoonniiccoo ddeellll’’aarreeaa la piana di bojano (circa 500 m s.l.m) è ubicata all’interno della catena appenninica centro-meridionale, alle falde settentrionali del massiccio carbonatico dei monti del matese (2050 m, m.te miletto) ed a sud dei rilievi argilloso-arenacei del sannio. essa è parte di una conca intermontana allungata per 20 km in senso nwse, larga non più di 4 km e drenata dal fiume biferno. quest’ultimo ha però solo in parte eroso la successione alluvionale e lacustre pleistocenica che riempie il fondo della depressione; dati di affioramento e di sottosuolo indicano infatti una potenza di circa 150-200 m per la porzione del pleistocene medio-superiore (ge.mi.na., 1963), suddivisi tra depositi di conoide e sabbie e limi lacustri alla base. in particolare, l’area di campochiaro è caratterizzata dalla presenza di una potente conoide inattiva (oltre 90 m in sondaggio; fonte erim), reincisa dal torrente la valle, e datata, nel suo ordine più recente, tra l’ultimo massimo glaciale ed il passaggio all’olocene (rispettivamente 18 ka e 10 ka; guerrieri et al., 1999). l’elemento più importante dell’area ai fini sismotettonici è il sistema di faglie bordiere settentrionali del massiccio del matese (n-matese, fig. 1). tale sistema, infatti, oltre aver guidato l’evoluzione neotettonica del bacino, è probabilmente responsabile dei principali terremoti che hanno origine nella piana. esso è composto, da nw verso se, almeno da tre faglie principali ad andamento nw-se (faglia del m.te patalecchia), wnw-ese (faglia di bojano) e wswene/e-w (faglia di campochiaro). tali faglie affiorano chiaramente lungo tutto il versante settentrionale del matese, formando a tratti una scarpata che interrompe bruscamente il profilo dei versanti e sfalsando la successione di paleosuperfici, scolpite originariamente alle stesse quote, a monte ed a valle delle faglie stesse sui versanti sudoccidentali e nordorientali del bacino di bojano (fig. 2; bosi et al., 1997). esse dislocano, inoltre, depositi lacustri datati almeno a 0.6 ma (datazione 39ar/40ar; corrado et al., 2000) ed attualmente sollevati più di 300 m sopra i corrispondenti depositi nell’attuale piana, oltre a brecce di pendio del pleistocene (faglia di bojano; fig. 3), depositi di ricaduta vulcanica (ii ciclo di roccamonfina, circa 0.3 ma, de rita and giordano, 1996: v. bosi, comunicazione personale; faglia del m.te patalecchia) e depositi alluvionali del pleistocene superiore (faglia di campochiaro; guerrieri et al., 1999). inoltre, in occasione del terremoto del 1805, diverse fonti storiche contemporanee descrissero l’apertura di fenditure lungo i versanti di bojano (faglia di bojano) e guardaregia (faglia di campochiaro); queste notizie, seppur con le dovute cautele, potrebbero testimoniare l’occorrenza di fenomeni di fagliazione superficiale e quindi l’attivazione delle suddette faglie. infine, dati provenienti dall’elaborazione di breakout di pozzi profondi (montone et al., 1999), indicherebbero per quest’area un estensione in atto in direzione ne-sw, compatibile con la direzione e cinematica delle faglie bordiere del n-matese. fig. 1 – modello digitale del terreno nell’area del confine molisano-campano. e’ evidenziata la struttura bordiera settentrionale dei monti del matese, composta principalmente dalle faglie del m.te patalecchia, di bojano e di campochiaro. ogni faglia in affioramento si compone di diversi segmenti, non rappresentati alla scala del disegno. a questa struttura sono attribuibili i più forti terremoti con origine nella piana. a tratto sottile sono evidenziate le faglie tra pesche e angelo in grotte. la stella indica il santuario di ercole. digital elevation model of the region between molise and campania. bold lines show the northern matese massif structure, composed by the mt. patalecchia-bojano-campochiaro fault system. this system is responsible for the strong local seismicity. thin lines show the possibly antithetic faults of pesche and angelo in grotte. white star is the hercules’s sanctuary site. 157analisi archeosismologiche nel santuario ... ssiissmmiicciittàà ssttoorriiccaa come prima anticipato, l’area della piana di bojano è stata in passato zona epicentrale di terremoti catastrofici, l’ultimo dei quali è il ben documentato evento del 26 luglio 1805 (ma=6.6, io=x mcs: gruppo di lavoro cpti, 1999; circa 5500 vittime). non considerando i numerosi eventi di medio-bassa magnitudo, non capaci di produrre fagliazione superficiale, altri due terremoti distruttivi sono noti dalle fonti per aver colpito la zona in questione: quello del 346 d.c. (ben noto alla letteratura archeologica) e quello del 5 dicembre 1456. a questi vanno aggiunti gli eventi del 4 settembre 1293 e del 9 settembre 1349. il primo è noto attraverso diverse fonti primarie che attestano un elevato grado di danneggiamento a bojano, tocco caudio, isernia e sessa aurunca (boschi et al., 1995), mentre il secondo, uno dei più importanti ed estesi terremoti medievali, ebbe effetti rovinosi ad isernia ma non riporta fonti dirette per bojano o per altri paesi della piana. iill tteerrrreemmoottoo ddeell 334466 dd..cc. questo evento è identificato in genere con quello di cui fornisce notizia girolamo (ca. 340-420) nella sua rielaborazione del chronicon di eusebio di cesarea: “dyrrachium terrae motu corruit et tribus diebus ac noctibus roma nutavit plurimaeque campaniae urbes vexatae” (durazzo rovinò per un terremoto, roma traballò per tre giorni e tre notti e molte città della campania furono scosse). la datazione del terremoto, non tramandata da girolamo, si basa sull’anno di composizione del de errore profanarum religionum di giulio fìrmico materno (vissuto verso la metà del iv sec. d.c.), ovvero il 346, trattato in cui lo scrittore siracusano fa riferimento ai frequenti tremori che a quel tempo scuotevano la terra: “terram omnem circumfluunt maria, et rursus inclusa oceani ambientis circolo stringitur, caeli etiam rotonda sublimitate operitur, perflatur ventis, aspergitur pluviis, et timorem suum assidui motus tremoribus confitetur” (la terra è ovunque circondata dal mare e d’altra parte è limitata dall’abbraccio degli oceani, il cielo la ricopre con la sua sfera grandiosa, i venti la percorrono, è bagnata dalle piogge, e manifesta il suo timore con incessanti terremoti). e’ lecito ritenere che fìrmico materno avesse accennato, nel comporre il testo, ad un fenomeno recente che destava il suo interesse. la localizzazione nel sannio di tale evento deriva invece dal rinvenimento in questo territorio di iscrizioni lapidee datate alla metà del iv secolo, le quali testimoniano che la regione fu colpita da terremoti, che numerose costruzioni furono intraprese dallo stato e che le mura delle città furono restaurate. si può addirittura ipotizzare che l’avvenuta separazione del samnium dalla campania e la creazione, quindi, di una provincia samnitium potrebbe essere stata voluta per concentrare l’intervento amministrativo imperiale sulle zone disastrate dal terremoto del 346 (camodeca, 1972), la qual cosa, se vera, rafforzerebbe ulteriormente l’impressione sulla severità del terremoto. nel gruppo delle epigrafi riguardanti gli interventi di restauro nel sannio per opera di fabius maximus (primo governatore della provincia, circa 352/7) e di autonius iustinianus (probabilmente quarto governatore dopo il 375) si osserva però che il termine terrae motus è presente solo in quattro casi, ma esplicitamente leggibile solo in due (cil ix 2338, edita da camodeca, 1972, fig. 2 – schema dei rapporti altimetrici tra le paleosuperfici scolpite nei versanti di roccamandolfi, cantalupo e macchiagodena (fig. 1), lungo un ipotetico profilo sw-ne. e’ evidente una buona correlazione tra la quota delle diverse superfici nell’hangingwall della faglia del n-matese (faglia di bojano), ma non con quelle individuate nel footwall. *i trattini inclinati sono rappresentativi dell’escursione altimetrica di ciascun complesso di superfici che compongono ogni “paleosuperficie” e non ne denotano quindi né una continuità né la pendenza. sketch of the elevation relationships among pleistocene remnant surfaces carved in the hillslopes of roccamandolfi, cantalupo and macchiagodena (see fig. 1 for location), along a imaginary sw-ne trending section. the good accordance between the cantalupo and macchiagodena successions (and partly of roccamandolfi, in the bojano fault hangingwall) is not observed by the roccamandolfi’s one (bojano fault footwall). note that the sloping lines represent the altimetrical range of each complex of surfaces that compose every remnant surface; therefore, the lines do not imply any continuity or gradient of the latter. fig. 3 – veduta delle brecce pleistoceniche raddrizzare e tettonizzate lungo il versante di bojano, in prossimità della zona di faglia. view of the warped pleistocene breccia (note the quasi-vertical dip) in the bojano fault zone. 158 p. galli, f. galandini & s. capini collegata a fabius maximus e cil ix 2638, edita da buonocore, 1992, collegata ad autonius iustinianus), pur senza alcun indizio cronologico; tuttavia, giacché molte altre epigrafi (18) attestano gli interventi nel sannio di questi due governatori (gambardella, 2001), si può ragionevolmente desumere che gran parte di esse possano riferirsi allo stesso evento sismico del 346. ben più complessa è invece la localizzazione epicentrale di questo evento (ubicata nel matese sudorientale secondo gruppo di lavoro cpti, 1999) e della relativa struttura sismogenetica. l’area interessata dalle lapidi è infatti molto vasta (fig. 4) e le lapidi con l’esplicita menzione del terremoto come causa della rovina sono ubicate solo ad isernia ed alife e dubitativamente a telesia. considerando anche i dati preliminarmente acquisiti nei teatri di sessa, calvi, teano, venafro (crolli estesi e simultanei di gran parte delle strutture e delle decorazioni, compatibili con la metà del iv secolo d.c.; dati inediti degli scriventi in collaborazione con la soprintendenza di napoli e caserta) e da indizi ad atripalda-abellinum (colucci pescatori, 1986), l’ubicazione epicentrale (o di uno degli epicentri, nel caso si trattasse di un evento multiplo) del terremoto del 346 nel bacino di bojano appare non sufficientemente supportata dalle attuali conoscenze, fatto salvo che un notevole danneggiamento sia comunque derivato nella piana a seguito di questo evento. iill tteerrrreemmoottoo ddeell 11445566 . questo evento è, insieme a quello del 1349, l’evento medievale più forte, esteso e complesso d’italia. si tratta, come per il 1349, di un evento multiplo, con più aree epicentrali sgranate lungo la catena appenninica (e quindi legate a più strutture sismogenetiche), verosimilmente almeno tre: la più meridionale nel beneventano (io=xi mcs), una intermedia nella piana di bojano (io=x-xi) ed una più settentrionale nell’area dei monti della meta e mainarde (io=x-xi; fig. 5). in particolare, lo scenario di danneggiamento dell’area di bojano risulta addirittura più grave di quello che si ripresenterà per il terremoto del 1805. furono quasi completamente distrutti bojano, frosolone, vinchiaturo, macchiagodena, mentre subirono danni gravissimi baranello, ripamolisani, sepino, carpinone, cercepiccola, spinete, colle d’anchise, campochiaro, san massimo e molti altri. la distribuzione del danneggiamento permette inoltre di ipotizzare che la struttura responsabile dell’evento sia localizzata nella piana stessa, anche se notizie di effetti cosismici riconducibili, per esempio, a fagliazione superficiale, sono scarse e frammentarie. a questo proposito si ricorda che le notizie contenenti descrizioni semi-analitiche degli effetti di superficie compaiono nelle relazioni sui terremoti solo a partire dal 17° secolo (p.e. con i terremoti del 1627 nel gargano e del 1638 nella sila; galli and bosi, 2003). iill tteerrrreemmoottoo ddeell 11880055. l’evento del 26 luglio del 1805 è l’ultimo terremoto distruttivo che ha colpito i paesi della piana di bojano. furono quasi completamenfig. 4 distribuzione parziale dei possibili effetti del terremoto convenzionalmente riferito al 346 d.c. il simbolo dei crolli si riferisce a crolli estesi e simultanei rinvenuti prevalentemente nei teatri dei siti a cui sono riferiti, cronologicamente compatibili con la data del 346 (dati preliminari acquisiti in collaborazione con la soprintendenza di napoli e caserta, ad eccezione di peltuinum: sommella, 1989). le lapidi sono tutte riferite a restauri operati dai governatori del sannio; la t indica l’esplicita menzione del terremoto quale causa della rovina (ipotizzata a saepinum). e’ inteso che più terremoti potrebbero avere concorso a questo quadro di danneggiamento. il santuario di campochiaro è indicato dalla stella. incomplete distribution of earthquake-induced effects related to the 346 ad event. collapse symbol refers to extensive and simultaneous collapses surveyed mainly in the theatres of the named towns, that are chronologically consistent to the 346 ad date (unpublished data of the authors, gathered with the collaboration of naples and caserta superintendence, with the exception of peltuinum – abrutii region – cited by sommella, 1989). memorial stones are all referred to restoration/rebuilding promoted by samnium governors; t indicates the explicit mention of earthquake-induced damage (only hypothesized in saepinum). it is worth noting that showed damages could have been induced by more than one earthquake. the star is the campochiaro hercules’s sanctuary 159analisi archeosismologiche nel santuario ... te distrutti i paesi di baranello, frosolone, carpinone, guardiaregia, cantalupo, san polomatese e san massimo, mentre moltissimi altri nel bacino e nelle zone limitrofe subirono danni gravissimi. la distribuzione delle massime intensità (fig. 6), così come per il 1456, delinea un’area epicentrale centrata sulla piana e legata, molto probabilmente, all’attivazione della struttura bordiera del matese (faglie del m.te patalecchia-bojanocampochiaro; fig. 1) e, possibilmente, delle sue antitetiche lungo il versante sudoccidentale dei monti del sannio (es., faglie di pesche-angelo in grotte; fig. 1). come prima accennato, esistono a riguardo indicazioni provenienti da fonti primarie che evidenziano l’occorrenza di fratture e fenditure avvenute lungo i versanti settentrionali del matese, ed in particolare lungo quello di guardiaregia (faglia di campochiaro; d’onofrio, 1805; poli, 1806), e tra pesche e angelo in grotte (versante nw della piana, fortini, 1984). no), è posto su una coltre detritica calcarea depostasi ai piedi del versante carbonatico cretacico di colli della defenza (fig. 8). da dati di superficie e da sondaggio (erim) il detrito calcareo ha uno spessore nell’ordine dei 20 m ed appoggia su un substrato argilloso-marnoso, presumibilmente appartenente alla formazione tortoniana del flysch di pietraroia (tortoniano-messiniano). a valle del santuario, ed in rapporto parziale di incassamento con il detrito, affiorano i depositi alluvionali della conoide di campochiaro, interdigitati distalmente con il riempimento lacustre finale della piana (inizio dell’olocene secondo guerrieri et al., 1999). poco a monte del santuario affiora un tratto del liscione in calcari della faglia di campochiaro, la quale borda con continuità tutto il versante settentrionale di colli della defenza (figg. 7-8). misure strutturali effettuate lungo il piano, sino al paese di guardiaregia, evidenziano una direzione media da n80w (ad est) a n70e (ad ovest); giunta alla longitudine di campochiaro la faglia ruota gradatamente in senso antiorario e si dispone circa wsw-ene. indicatori cinematici rilevati sul piano di faglia (strie) in corrispondenza del santuario fig. 5 – distribuzione parziale delle massime intensità valutate per il terremoto del 1456 (i>viii mcs). le ellissi a tratteggio indicano le tre possibili aree epicentrali. il santuario di campochiaro è indicato dalla stella. highest intensity datapoints distribution of the 1456 earthquake (i>viii mcs). ellipses show the three possible epicentral areas. star is the hercules’s sanctuary. fig. 6 – distribuzione parziale delle massime intensità valutate per il terremoto del 1805 (i>viii mcs). il santuario di campochiaro è indicato dalla stella. notare come il piano quotato sia molto simile a quello della zona intermedia rappresentata nella fig. 5. highest intensity datapoints distribution of the 1805 earthquake (i>viii mcs). note the similarity of the datapoints distribution with that of the central mesoseismal area in fig. 5. star is the hercules’s sanctuary. aannaalliissii aarrcchheeoossiissmmoollooggiicchhee nneell ssaannttuuaarriioo ddii eerrccoollee ssiittuuaazziioonnee ggeeoollooggiiccaa llooccaallee. il santuario sannita di ercole, localizzato in toponimo i.g.m. civitella (f. 162 iii 160 evidenziano una componente trascorrente destra (pitch 125°). l’analisi delle fotografie aeree del volo base igm del 1954 ha permesso di individuare l’area del santuario (ancora non scavata e coperta dalla vegetazione) su di un ripiano tra la scarpata di faglia principale a monte (a direzione locale ene-wsw) ed una scarpata secondaria a valle, quest’ultima con direzione ne-sw, scolpita nelle forme del deposito detritico (fig. 8). saggi di scavo all’interno del santuario hanno permesso di constatare che lo stesso è interamente fondato su detrito calcareo composto da clasti eterometrici (ϕ 5÷20 cm) subangolosi, addensato, privo di matrice ed altamente permeabile. dall’esame delle fotografie aeree non sono invece emersi indizi di movimenti gravitativi o di erosione accelerata; l’area è, tra l’altro, densamente forestata e, dal confronto con le immagini del 1954, lo è maggiormente oggi d’allora. cceennnnii ssuullllaa ssttoorriiaa ddeell ssaannttuuaarriioo. come accennato, l’area del santuario è un cantiere di scavo in evoluzione da diversi anni ed è lungi dall’essere stata interamente scavata e studiata. tuttavia è possibile, sulla base delle emergenze sinora raccolte, ricostruire le principali tappe evolutive del sito, al fine di meglio comprendere le fasi deformative che lo hanno interessato. la prima costruzione individuata è un edificio rettangolare, presumibilmente eretto nella prima metà del iv secolo a.c. e forse già di pertinenza di un luogo di culto. a questo edificio, distrutto come vedremo in seguito, si sovrappone nel iii secolo un edificio porticato (fig. 9) che fiancheggia il percorso di ingresso all’area sacra (questo edificio porticato presuppone l’esistenza di un importante edificio di culto ubicato poco a monte, le cui tracce, a causa delle successive fasi di smantellamento e ricostruzione, non sono tuttavia ancora emerse). e’ probabile che in questa fase, o poco prima, venga anche costruita la cinta muraria in opera poligonale (sicuramente dopo il 290 a.c., fine delle guerre contro roma ed inizio di un periodo di stabilità economica e politica). a questa fase di iii secolo subentra, intorno al 130 a.c. (come suggerito dal rinvenimento di monete nelle fondazioni e bolli laterizi) un nuovo tempio con valenza di santuario territoriale della capitale dello stato (fig. 10). il santuario sopravvive, tra probabili saccheggi delle milizie di silla (89 a.c.) e crisi post-belliche, sino al tempo di augusto, quando riacquista una certa importanza, seppure forse solo a livello locale. il sito è quindi frequentato per tutto il i-ii secolo d.c., come attestato dal materiale votivo rinvenuto, così come nel iii-iv secolo, ove sembra addirittura possibile una ripresa del culto. e’ probabilmente collocato nel iv secolo, infine, l’abbandono del culto di ercole, a cui subentra un uso del sito precipuamente legato alle vie di comunicazione nella piana (ed in particolare all’attiguo passaggio del “tratturello” per allifae). iill ccoonntteessttoo ddeeffoorrmmaattiivvoo. la vicinanza del santuario di ercole alla faglia bordiera di campochiaro (poche decine di metri a sud) e la presenza a nord di una scarpata nella coltre detritica che ospita il sito (visibile nelle foto aeree i.g.m. del 1954), sono gli elementi che hanno guidato un sopralluogo nell’area cinta dalle mura poligonali. p. galli, f. galandini & s. capini fig. 7 faglia di campochiaro. piano in roccia affiorante all’interno dell’area del santuario. campochiaro fault. fault plane affecting the carbonate substratum within the hercules’s sanctuary area. fig. 8 modello digitale del terreno dell’area di campochiaro. e’ evidenziato l’andamento della faglia di campochiaro e della scarpata identificata poco a valle della stessa (linea tratteggiata). il retinato scuro evidenzia la distribuzione della conoide di campochiaro. la stella indica il sito del santuario. isoipse ogni 50 m. (elaborazione da dati altimetrici i.g.m., aut. 5410, 6/6/2001) digital elevation model of the campochiaro area. bold line is the campochiaro fault trace (bedrock fault scarp), while dotted line is the fault scarp carved in the slope-derived debris. hatched area shows the campochiaro late pleistocene-holocene alluvial fan. star is the hercules’s sanctuary. qui, grazie agli scavi archeologici, in asse alla scarpata si osserva una dislocazione delle murature degli edifici attigui all’area del tempio e, più a nord, della cinta muraria, lungo un allineamento n30e. la dislocazione ha una componente sia orizzontale (destra) che verticale, e le strutture murarie di diversa fase non appaiono dislocate della stessa entità (fig. 9). questa prima osservazione suggerisce che un primo evento di dislocazione sia avvenuto tra le varie fasi edilizie e che, anzi, possa essere stata una concausa della distruzione di un edificio e la ricostruzione di un altro. la dislocazione successiva degli edifici non è “sigillata” o vincolata da alcun’altra fase edilizia o da livelli e/o depositi storici o connessi all’attività del versante, anche se le operazioni preliminari di riesumazione delle strutture sepolte potrebbero avere eliminato eventuali livelli di sutura contenuti nella coltre superficiale. ciò implica che non si ha il termine ante quem per l’ultima dislocazione delle strutture. aannaalliissii ppaalleeoossiissmmoollooggiicchhee. al fine di verificare la natura della dislocazione delle murature ed escludere eventuali cause locali di instabilità degli edifici, quali cedimenti, sottoscavazione della fondazione, etc. (che comunque sarebbero difficilmente compatibili con la geometria, estensione e cinematica delle deformazioni, nonché con le caratteristiche geomeccaniche dell’ammasso roccioso di fondazione) è stata scavata una trincea attraverso la prosecuzione della linea di dislocazione, in un tratto dell’area del santuario privo di edifici (fig. 10). le dimensioni della trincea sono state necessariamente ridotte (3 m di lunghezza e meno di 2 m di profondità), a causa della vicinanza di importanti emergenze archeologiche e del conseguente uso di un miniescavatore dalle ridotte prestazioni. i depositi esposti sulla parete della trincea sono esclusivamente caratte161analisi archeosismologiche nel santuario ... fig. 9 veduta d’insieme degli ambienti di iv secolo a.c. (spigolo destro in alto; 1) e parte del porticato (basoli a destra; 2) e dell’edificio di iii secolo (filari a sinistra; 3) costruito sulle rasature del primo. e’ evidente la scarpata di faglia (a) che interessa l’area, dislocando le murature ed il piano di calpestio. la scarpata prosegue verso ene (sinistra), interessando altri locali e le mura di cinta in opera poligonale, e verso wsw (destra), ove è stata scavata la trincea paleosismologica (b). view of the 4th cent. bc room (1) and part of the 3rd cent. bc colonnade (sparse white stones, right side; 2), and of the 3rd cent. bc structure built over the former 4th cent. walls (3). “a” indicates the fault scarp carved within the pavement of the 4th cent. bc room. the scarp continues toward ene (left), affecting other rooms and the “opus polygonal” walls, and toward wsw (right), where we dug the paleoseismological trench (b). fig. 10 schema topografico dell’area del santuario (nord ruotato). il segmento della faglia a tratto continuo è quello direttamente investigato e visibile nella trincea paleosismologica e negli scavi archeologici negli ambienti di iv e iii secolo a.c.. a tratteggio è indicato il proseguimento a monte e valle della scarpata di faglia. i dentini e la freccia indicano il lato ribassato e il verso della componente orizzontale del movimento. notare l’andamento irregolare ed il disassamento della cinta muraria in opera poligonale nella fascia di attraversamento della faglia. il sentiero che si dirige verso sud corrisponde all’antico tratturello per allifae, dopo la sua biforcazione nella piana dal tratto principale pescasseroli-candela. sempre a sud, poco fuori carta, affiora la scarpata di faglia in roccia riportata nelle figg. 7-8. topographical sketch of the sanctuary area. bold line is the investigated sector of the fault, exposed inside the trench and in the archaeological excavations of rooms of 4th and 3rd cent. bc. dashed line is the not-excavated fault scarp. teeth on downthrown side; arrows indicates the versus of horizontal motion. it is worth noting the irregular attitude and the shift of the “opus polygonal” walls within the fault crossing-belt. few meters southward there outcrops the carbonate fault scarp shown in fig. 7. rizzati da ghiaie calcaree subangolari ed eterometriche, appartenenti al corpo detritico sviluppato lungo la fascia pedemontana. come evidenziato nelle figg. 11-12, essi sono interessati da una fascia deformativa larga pochi decimetri e contenuta da piani di taglio lungo i quali i clasti sono in parte allineati ed embricati (unità 6 in fig. 11). e’ stato possibile individuare diversi corpi ghiaiosi con caratteristiche granulometriche e tessiturali differenti (unità 1-5 in figura 11). in particolare le unità 3-5 (footwall) mostrano una buona stratificazione ed un buon grado di addensamento, oltre che una pedogenizzazione della parte alta dell’unità 3. le unità 1-2 (hangingwall) mostrano invece un assetto massivo, caotico e sono scarsamente addensate; l’unità 1 si apre a cuneo ed è caratterizzata da abbondante matrice sabbiosa. l’unità 6, come anticipato, è composta da ghiaie tettonizzate, presumibilmente di pertinenza dell’unità 3. oltre alla 6 anche le unità 3-5 e la 2 sono coinvolte nella deformazione, essendo trascinate ed uncinate nel verso del movimento. il suolo attuale rimaneggiato copre e sigilla la deformazione. la totale mancanza di livelli storici nella sezione (tutti i depositi sono sterili) lascia pensare ad una asportazione recente (naturale o più probabilmente antropica) degli orizzonti più superficiali. nel complesso, seppur non vincolata cronologicamente da nessun dato archeologico o assoluto (la natura dei depositi non ha permesso alcuna datazione assoluta, es. c14), la sezione esposta evidenzia chiaramente la presenza di un movimento tettonico che ha interessato la successione detritica; l’intensa strutturazione della fascia di deformazione e la geometria e lo spessore dei depositi nell’hangingwall lasciano ipotizzare l’occorrenza di più eventi di dislocazione. in particolare, l’unità 2 (ed anche l’unità 1, che però è elisa superiormente) rappresenta probabilmente un cuneo colluviale depositato al piede di una scarpata formatasi all’atto di un evento di fagliazione, 162 p. galli, f. galandini & s. capini fig. 11 – schema della parte centrale della trincea paleosismologica scavata trasversalmente alla fascia deformativa che disloca gli edifici connessi al tempio, in un’area a sud degli stessi. la mancanza di reperti archeologici e di depositi databili al carbonio 14 non permette di vincolare cronologicamente i movimenti presenti. la strutturazione dei depositi e la geometria tipo “colluvial wedge” dell’hangingwall è comunque indicativa di ripetuti movimenti cosismici. sketch of the central sector of the trench excavated across the deformation belt affecting the sanctuary buildings. the lack of archaeological findings and of 14c datable deposits do not allow to constrain the age of offset. warping of levels and reorienting of clasts, together with the presence of several shear planes within this narrow belt, highlight the occurrence of repeated displacement events. legend: 1, loose calcareous gravel, in abundant sandy matrix; 2, loose gravel, massive.; 3, heterometric gravel in sandy matrix, slightly pedogenized; 4, fine gravel horizon in silty-sandy matrix; 5, coarse gravel in scarce sandy matrix (brownish); 6, highly tectonized gravel, with dragged and re-oriented pebbles along the shear planes (unit 3?). fig. 12 – dettaglio della zona di faglia esposta nella trincea “paleosismologica”. i due allineamenti di frecce contengono la fascia di ghiaie interessate da piani di taglio e trascinate nel verso del movimento (notare i clasti allineati). i numeri delle unità sono gli stessi della fig. 11. (a) è l’orizzonte pedogenizzato dell’unità 3. blow-up of the fault zone excavated in the paleoseismological trench. the two arrows alignments evidence the gravels belt affected by shear planes and dragged by the fault (note dragged and re-oriented clasts). units numbers are the same of fig. 11. (a) is the pedogenized horizon within unit 3. successivamente coinvolto a sua volta e trascinato da uno o più eventi. l’età del deposito detritico pedemontano (e delle dislocazioni che lo interessano), come precedentemente accennato, è verosimilmente olocenica, mentre la sua parte sommitale, indagata dalla trincea, potrebbe appartenere alle ultime fasi di attività del versante, ad esempio a quelle legate ai disboscamenti neolitici. llee ddiissllooccaazziioonnii nneeii mmuurrii. come anticipato, l’entità della dislocazione valutata negli edifici di diversa fase non è uguale; va inoltre tenuto presente che essa è un valore cumulato, invero sommatoria di tutti gli eventi di fagliazione eventualmente occorsi dall’edificazione delle prime strutture ad oggi. la scansione temporale di questi eventi è funzione della disponibilità di livelli cronologicamente definibili interessati o sigillanti la dislocazione, nonché della conoscenza approfondita della sismicità storica della regione. il rigetto orizzontale misurato in asse alla linea di dislocazione varia tra 130 e 140 cm nell’edificio rettangolare di iv secolo a.c.. questo rigetto è comprensivo, in parte, della fascia di deformazione continua affiorante, particolarmente evidente nel muro settentrionale dell’edificio. gli scavi archeologici hanno inoltre messo in evidenza il piano di calpestio di questo edificio a cavallo della dislocazione e la “scarpata” (fig. 9, 13) che ne separa la parte nel footwall da quella nell’hangingwall. il rigetto verticale tra le due parti è di circa 130 cm. il rigetto orizzontale misurato nell’edificio sovrimposto a quello di iv secolo e fronteggiato da un portico, di cui si riconosce un tratto di crepidine (marciapiede), varia tra 50 e 80 cm nei muri e-w (fig. 14), ed è di circa 60 cm in un tratto di muro perpendicolare al primo, anche se l’esiguità dell’affioramento di quest’ultimo nel footwall non permette una valutazione precisa dell’insieme della deformazione continua. più complessa è anche la valutazione del rigetto verticale di questo edificio; confrontando le quote della soglia e della risega di fondazione sul muro settentrionale degli ambienti di fig. 9 e 13 (assunto che fossero alla stessa quota) si ottiene un valore di circa 70 cm, molto simile a quello ottenuto confrontando la quota di spiccato della base della colonna del porticato e del basolato della crepidine (75 cm; fig. 14). a nordest di questo gruppo di edifici la faglia interseca anche la mura di cinta in opera poligonale (fig.15). infatti, circa a metà del tratto sw-ne delle mura, le stesse presentano spanciature, disassamenti ed un netto mutamento della tecnica costruttiva: grossolana e con predilezione per gli allineamenti orizzontali (di blocchi di piccole dimensioni) nell’hangingwall ed accurata ed in opera poligonale nel tratto rettilineo finale nel footwall. una buona tecnica è nuovamente impiegata in prossimità della porta occidentale (fig. 10), nell’hangingwall, ma lontano dalla zone di faglia. l’angolo di incidenza tra la faglia e la cinta è molto basso ed è quindi molto difficile valutare l’entità della dislocazione. quella orizzontale è comunque superiore a 1.5 m, mentre, a causa della ricostruzione degli alzati e della loro successiva rovina, nonché della pendenza irregolare del muro (che segue, in parte, quella del versante) non vi è modo di valutare quella verticale. nel complesso il rigetto totale, risultante dalle componenti orizzontali e verticali del movimento, è rt=180 cm (fig. 16). quello relativo ai muri di iii secolo a.c. è r2=110. ne consegue che la dislocazione relativa al primo evento è r1=rt-r2=70 cm. questi rigetti sono da intendersi minimi, in quanto solo in parte tengono conto della deformazione continua a più larga scala (quale quella che potrebbe avere “registrato” un elemento esteso come, ad esempio, la cinta muraria, se diversamente orientata). aallttrrii iinnddiizzii aarrcchheeoossiissmmiiccii.. per quanto esposto nei precedenti capitoli, gli eventi di fagliazione riconosciuti nel santuario di ercole, ed in particolare il primo e sconosciuto alle fonti, devono essere riferiti a terremoti di origine locale, di elevata magnitudo (m 6.5) e forte capacità distruttiva (io x mcs). a questi vanno però sommati, nell’intervallo di esistenza del santuario, eventuali effetti dovuti al risentimento locale di forti terremoti con area epicentrale anche distante. mentre la quasi totale mancanza di alzati non permette di evidenziare alcun indizio di danneggiamento “sismico”, la presenza della monumentale ed incompiuta porta occidentale, rinvenuta in stato di crollo, e la cronologia del materiale strettamente votivo possono suggerire alcune considerazioni sulla sorte finale del santuario. innanzitutto, sia la documentazione numismatica che quella 163analisi archeosismologiche nel santuario ... fig. 13 veduta della scarpata (a, free face) nel piano di calpestio dell’edificio di iv secolo a.c., “riesumata” dagli scavi archeologici. b è il piano di calpestio dell’edificio di iv sec. a.c. c sono le mura di iv secolo a.c. view of the fault scarp (a, free face) affecting the pavement (b) of the 4th cent. bc room (c), exhumed by the archaeological excavation. clasts are the loose-stone-foundation. ceramica, dei vetri e delle lucerne testimoniano un marcato utilizzo del santuario tra il iii e iv secolo d.c., almeno sino al secondo quarto del iv secolo (monete di costantino del 325-330 d.c.), mentre l’assenza di materiale più tardo e alto medievale indica una forte ed improvvisa cesura della frequentazione. anche i vetri, ed in particolare la classe raffinata di quelli incisi a “ruota e punta”, databili tra la seconda metà del iii e il iv secolo d.c., testimoniano un perdurare del culto sino a questo momento ed un improvviso abbandono poi. a questo si aggiunga che la porta occidentale (fig. 10) è stata rinvenuta parzialmente al suolo, comprensiva della volta con i conci embricati in posizione primaria di crollo, sopra uno strato di interro molto prossimo al piano di calpestio relativo alle fasi ultime di frequentazione. ed analogamente, molto altro materiale lapideo proveniente dal sovrastante tempio è stato trovato subito al di sopra degli ultimi livelli di uso. in altre parole, quindi, il crollo simultaneo della porta in una fase ancora di uso del passaggio e la cesura nel materiale votivo indicherebbero l’occorrenza di un evento distruttivo nella seconda metà del iv secolo d.c.. in attesa di ulteriori dati di scavo, sembrerebbe lecito ipotizzare che questo evento possa essere identificato con il terremoto del 346 d.c., per il quale, come prima ricordato, sono attestati danni nella regione e, presumibilmente, anche nella vicina saepinum. ccrroonnoollooggiiaa ddeeggllii eevveennttii. per quello che concerne la possibile cronologia degli eventi deformativi, essa può essere tracciata a partire dalle emergenze relative all’edificio attiguo al porticato (fig. 9); esso fu costruito sulle rasature di quello di iv secolo e sopra un reinterro messo in opera per livellare la scarpata prodottasi nel primo evento di fagliazione. i materiali rinvenuti nel reinterro sono di iii secolo a.c. (forse entro la metà del secolo), e quindi il primo evento di fagliazione documentato è cronologicamente contenuto tra la prima metà del iv secolo (età del primo edificio fagliato) e la metà del iii secolo. e’ però ragionevole pensare che l’evento sia più prossimo all’età della ricostruzione, e quindi alla metà del iii secolo, piuttosto che a quella del primo edificio (la qual cosa avrebbe comportato un abbandono dell’area per circa un secolo, fatto questo escluso dalla continuità di frequentazione testimoniata dal materiale rinvenuto nell’area). e’ poi possibile ipotizzare che la cinta muraria, il cui rigetto non è inferiore a quello delle mura di iv secolo a.c., abbia anch’essa “registrato” questo primo evento. dal momento che le mura furono costruite dopo il 290 a.c., questo evento si potrebbe collocare nel secondo quarto del iii secolo a.c.; la cinta sarebbe stata quindi restaurata nel tratto interessato dalla deformazione da maestranze meno abili di quelle che l’avevano da poco edificata. un altro indizio indiretto proviene infine da un tesoretto disperso di monete bronzee prevalentemente campane, riferibili alla prima metà del iii secolo a.c.. nell’ipotesi (ammessa in archeosismologia) che il ritrovamento di un tesoretto testimoni l’abbandono dello stesso o per l’impossibilità di recuperarlo o per la scomparsa improvvisa di chi l’aveva nascosto, la datazione delle monete indica il termine ad quem o post quem della causa dell’abbandono, cioè nel caso specifico del possibile terremoto. l’evento o gli eventi successivi che hanno concorso all’attuale rigetto cumulato sulle strutture non hanno purtroppo alcun vincolo stratigrafico, se non il post quem dato dalla costruzione dell’edificio legato al porticato (metà del iii secolo od inizio del ii a.c.). per quanto il comportamento “caratteristico” di una faglia (schwartz e coppersmith, 1984) può non essere assunto come modello valido sempre e ovunque, la semplice osservazione dell’entità del rigetto del primo evento r1=70 cm comparata a quella totale rt=180 cm suggerisce l’occorrenza di sicuramente uno o più simili eventi di dislocazione/terremoti successivamente al primo (fig. 16). questi, per quanto ricordato nel capitolo dedicato alla sismicità storica, possono essere il terremoto del 1456, una cui area epicentrale ricade nella piana di bojano, ed il terremoto del 1805, per il quale, anzi, sono note dalle fonti storiche contemporanee informazioni su possibili effetti di fagliazione superficiale lungo la faglia di campochiaro. non è escluso, tuttavia, che altri eventi sconosciuti altomedievali (o dubitativamente quello del 346 d.c.) abbiano concorso, con entità 164 p. galli, f. galandini & s. capini fig. 14 – veduta verso est del muro meridionale dell’edificio di iv secolo a.c. (a). e’ evidente la dislocazione destra che interessa, con minore entità, anche i basoli del porticato edificato sulle rasature dell’edificio di iv secolo (b e d). notare l’uncinatura del muro di iv secolo che asseconda il trascinamento lungo il piano di dislocazione (frecce). sulla destra è visibile la scarpata prodottasi nel piano di calpestio di quest’ultimo edificio (linea tratteggiata) e quindi “cresciuta” a seguito di successivi eventi di fagliazione (c). view looking east of the southern wall of the 4th cent. bc building (a). note the horizontal (dextral) displacement which affects, with a minor offset, also the colonnade alignment (b and d). note also the warping of the 4th cent. bc walls, dragged by the fault motion (open arrows). c indicates the fault scarp affecting the pavement of the 4th cent. bc room (dashed line), which grew due to subsequent surface faulting events (c). diverse (nella fattispecie minori), al rigetto finale; come osservato lungo altre faglie (p.e. quella del fucino: galadini and galli, 1999b) il rigetto in un sito non è sempre costante da evento ad evento. inoltre, la faglia che attraversa il santuario potrebbe non essere l’espressione superficiale principale della struttura sismogenetica, registrando quindi dei rigetti non “rappresentativi” del comportamento della struttura profonda (si veda, p.e., schwartz and crone, 1985; mccalpin, 1987). ddiissccuussssiioonnee ee ccoonncclluussiioonnii il sito di ercole a campochiaro è il secondo caso in italia (vedi galadini and galli, 1999a), e tra i pochissimi nel mondo (vedi stiros, 1996; galli and galadini, 2001), per il quale sia stato evidenziato un fenomeno di fagliazione di strutture archeologiche circoscritte (i.e., edifici). l’analisi delle murature, supportata dallo studio dei rilievi topografici di dettaglio, dall’interpretazione aerofotografica e dallo scavo di una trincea paleosismologica, ha consentito, infatti, di individuare e caratterizzare la dislocazione orizzontale e verticale degli edifici di pertinenza del santuario sannita e della cinta muraria in opera poligonale; tale dislocazione, nell’ambito delle conoscenze del contesto geologico e della tettonica attiva del bacino di bojano, è riferibile al sistema di faglie bordiere del matese. in particolare, è stato riconosciuto un primo evento di fagliazione avvenuto nella prima metà del iii secolo a.c.. a questo evento, riconducibile ad un terremoto sconosciuto ai cataloghi sismici, deve essere associata un’elevata capacità di distruzione, simile a quella che accompagnò gli eventi del 1456 e 1805. a questi ultimi potrebbero invece essere riferite le successivi deformazioni che interessano il sito archeologico. questo fatto ha una diretta ed importante implicazione di carattere sismotettonico; assumendo che gli 165analisi archeosismologiche nel santuario ... fig. 15 veduta verso sud delle mura poligonali occidentali. la faglia attraversa la cinta con un basso angolo di incidenza e produce una estesa fascia di deformazione, impedendo una corretta valutazione dei rigetti. il tratto indeformato nel footwall (sinistra) mostra la tecnica raffinata utilizzata dai primi costruttori della cinta; nell’hangingwall (destra) prevale una tecnica rozza a filari orizzontali, opera di maestranze non specializzate chiamate a restaurare il muro dislocato dall’evento della prima metà del iii secolo a.c.. la linea bianca indica la traccia del piano di faglia; le frecce suggeriscono il verso del movimento. view looking south of the western “opus polygonal” walls. the fault crosses the walls alignment with a low-angle of incidence, causing a wide deformation belt and hampering a correct evaluation of offsets. the undeformed walls built in the footwall (left) show the refined technique (polygonal stones) used by the first workers at the beginning of the 3rd cent. bc; conversely, in the hangingwall a crude technique is prevalent, due to the workers called to restore the walls displaced and ruined by the 3th cent. bc event. the white line suggests the fault plane attitude; arrows indicate the versus of relative motion. fig. 16 – schema dei rapporti stratigrafici tra le diverse fasi edilizie degli edifici a valle del santuario e loro successive dislocazioni (non in scala). sulle rasature di un ambiente di iv secolo a.c., dislocato di r1 (vedi testo) vengono innalzate altre mura ed un colonnato nel iii secolo a.c.. anche questi sono successivamente fagliati di un’entità r2, ascrivibile agli effetti cumulati dei terremoti del 1456 e 1805 o di altri eventi sconosciuti (per esempio di epoca alto medievale o, dubitativamente, dello stesso terremoto del 346 d.c.). a sinistra sono schematizzate le componenti del rigetto totale (orizzontale e verticale) per i singoli eventi (rt è il rigetto cumulato complessivo). sketch of the relationships between the 4th and 3rd cent. bc walls, and relative offsets. over the faulted and clipped ruins of the first building (offset r1), the samnites built a new room, which was later displaced by r2 (rt, total cumulative offset). note that the offset of the 4th cent. bc wall is greater than that of the 3rd cent. bc wall, this fact evidencing a faulting event between the two buildings. actually, r2 should be the cumulated offset due to the 1456 and 1805 earthquakes, which had their epicentral areas in the hangingwall of the n-matese faults system. however, we cannot exclude that other unknown seismic events contributed to the measured offset (possibly of high-middle ages, or the 346 ad earthquake that struck surely this area, but the epicenter of which is still debated). on the left, possible time history of the displacement events. eventi che hanno prodotto fagliazione nel sito di ercole siano effettivamente gli anzidetti terremoti, il comportamento sismogenetico della struttura bordiera del matese, in termini di tempi di ritorno, sarebbe assai poco costante, con due eventi simili (sensu “characteristic earthquake”, schwartz and coppersmith, 1984) separati da 1700 anni e seguiti da un terzo a soli 350 anni. anche “inserendo” l’evento del 346 d.c. (la cui area epicentrale non è però dimostrato essere nella piana di bojano) gli eventi avrebbero delle ricorrenze irregolari (600, 1100 e 350 anni). in altre parole, la periodicità che sembra caratterizzare altre strutture sismogenetiche appenniniche (2000±500 anni, galadini and galli, 2000) verrebbe completamente disattesa da quella del matese settentrionale. tuttavia, come ripetuto, a quest’ultima è associato l’evento del 1456, la cui sorgente non è esclusivamente locale, ma distribuita su più strutture sismogenetiche, esterne al bacino di bojano. pur nella ristretta visione dei fenomeni che agiscono su scale temporali ben più lunghe di quelle a noi note, è possibile ipotizzare che il 1456 sia una sorta di “fuori sequenza” nel complesso processo di accumulo e rilascio della deformazione in questo tratto appenninico. il carattere “anomalo” di questo evento è, d’altra parte, suggerito dalla sua specificità di evento multiplo ed ubiquitario per un lungo tratto della catena centro-meridionale e dalla sua vicinanza, nello spazio e nel tempo, con l’analogo sisma del 1349. si potrebbe, in altre parole, ipotizzare che il rilascio della deformazione nell’appennino centro-meridionale sia caratterizzato da forti terremoti generati da singole strutture sismogenetiche (p.e., la faglia del nmatese o quella del m.te marzano – terremoto dell’irpinia del 1980) alternati a sequenze nelle quali diverse sorgenti si attivano contemporaneamente, con possibili processi di innesco a catena di strutture contermini (vedi nostro et al., 1997). questa possibile conclusione comporta, ancora una volta, la necessità di rivedere le metodologie probabilistiche di analisi della pericolosità sismica in italia, al presente (p.e., lucantoni et al., 2001) ancorate a ipotesi di stazionarietà della sismicità e con eventi, financo i più forti, dispersi nelle zone sismogenetiche e svincolati dalle rispettive faglie. sulla base dei rigetti complessivi, invece, il rateo di movimento della struttura del matese sarebbe tra i più alti dell’appennino (vedi galadini and galli, 2000), approssimandosi infatti a 0.9 mm/yr. questo rateo, come ripetuto, è però del tutto giustificato e “testimoniato” dalla sismicità locale della piana. in definitiva, lo studio archeosismologico effettuato nel santuario di ercole ha comportato: • l’individuazione e caratterizzazione di un forte terremoto databile intorno al iii secolo a.c., sconosciuto ai cataloghi, che arricchisce il data base della sismicità storica della regione finalizzato a future valutazioni di pericolosità sismica; • l’individuazione di un evento di crollo e di cesura nella frequentazione del santuario nella seconda metà del iv secolo d.c., possibilmente riferibile agli effetti distruttivi del terremoto convenzionalmente riferito al 346, che determinò la fine della funzionalità del santuario di ercole; • la possibile identificazione della struttura sismogenetica di parte del catastrofico terremoto del 1456 con la faglia bordiera del matese; • la possibile conferma diretta dell’attivazione dello stesso sistema di faglie bordiere in occasione del terremoto del 1805; • la conseguente caratterizzazione della struttura sismogenetica del matese, in termini di periodicità e rateo di movimento; • lo spunto per la soluzione di alcuni problemi concernenti l’evoluzione architettonica e storica del sito e le possibili cause e spiegazioni di riedificazioni e dell’uso di tecniche edilizie. questo lavoro testimonia, in parte, come le potenzialità di un approccio archeosismologico nell’approfondimento delle conoscenze sulla sismicità in italia sono notevoli e ancora molto da esplorare. la ricchezza del nostro patrimonio archeologico e gli oltre due millenni da esso abbracciati rappresentano infatti una “miniera” di informazioni utili, se non uniche, nello studio della sismotettonica del nostro paese. rriinnggrraazziiaammeennttii domenico gambardella, nell’ambito di un contratto c.n.r., ha condotto un approfondimento sulle problematiche storico-archeologiche relative al terremoto del 346 d.c., al quale ci siamo riferiti. vittorio bosi ha partecipato al rilievo del sistema delle faglie bordiere del matese, fornendo dati inediti sulla stratigrafia del quaternario. questo lavoro non sarebbe stato possibile senza una stretta collaborazione tra geologi del terremoto, archeologi ed esperti di scavo della soprintendenza archeologica di campobasso e di napoli-caserta. siamo infine grati ad andrea tertulliani e ad un anonimo referee, i cui commenti e suggerimenti hanno migliorato il manoscritto originale. llaavvoorrii cciittaattii boschi e., ferrari g., gasperini p., guidoboni e., smriglio g., valensise g. 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(eds.), the use of historical data in natural hazard assessments, kluwer academic publisher, 3-27. galadini f. e galli p., 2001. gruppo di lavoro "archeosismologia", aiqua, associazione italiana per lo studio del quaternario, http://aiqua.irtr.rm.cnr.it/archeo.html galli p., 1999. active tectonics along the wadi arabajordan valley transform fault, journal of geophysical research, 110044, 2777-2796. galli p. and bosi v., 2002. the catastrophic 1638 calabrian earthquakes (southern italy). new insight from paleoseimologic investigation, journal of geophysical research, 108, b1, 10.1029/2002jb01713. galli p. and galadini f., 2001. surface faulting on archaeological relics. a review of case histories from dead sea to alps, tectonophysics, 333355, 291312. gambardella d., 2001. il terremoto del 346 d.c. alla luce della ricerca storico-archeologica, relazione inedita cnr-irtr, roma, 30 pp. ge.mi.na., 1963. ligniti e torbe dell’italia continentale, ilte, torino, 319 pp. gruppo di lavoro cpti, 1999. catalogo parametrico dei terremoti italiani. ing, gndt, sga, ssn, bologna 1999, 92 pp. guerrieri l., scarascia g., vittori e., 1999. analisi stratigrafica e geomorfologica della conoide tardo-quaternaria di campochiaro ed implicazioni per la conca di bojano in molise, il quaternario, 1122, 237247. lucantoni a., bosi v., bramerini f., de marco r., lo presti t., naso g. e sabetta f., 2001. il rischio sismico in italia, ingegneria sismica, 1188, 5-36. mccalpin j.p., 1987. geologic criteria for recognition of individual paleoseismic event in extensional environments: u.s. geological survey open-file report 87-673, 102-114. montone p., amato a., pondrelli s., 1999. active stress map of italy, journal of geophisical research, 110044, 25,595-25,610. nostro c., cocco m., belardinelli m., 1997. static stress changes in extensional regimes: an application to southern apennines (italy), bull. seismol. soc. am., 8877, 234-248. poli g.s., 1806. memoria sul tremuoto de’ 26 luglio del corrente anno, napoli. postpischl d. ed., 1985. catalogo dei terremoti italiani dall’anno 1000 al 1980. consiglio nazionale delle ricerche, progetto finalizzato geodinamica (cnr-pfg), quaderni de “la ricerca scientifica”, 111144, pp. 239. schwartz d.p. and coppersmith k., 1984. fault behavior and characteristic earthquakes: examples from the wasatch and san andreas faults, journal of geophysical reseaech, 8899, 5681-5698. schwartz d.p. and crone a., 1985. the 1983 borah peak earthquake: a calibration event for quantifying earthquake recurrence and fault behavior on great basin normal fault: u.s. geological survey open-file report 85-290, 153-160. stiros, s.c., 1996. identification of earthquakes from archaeological data. in: stiros, s., jones, r.e. (eds.), archaeoseismology, british school at athens, fitch laboratory occasional paper 7, 119152. stucchi m. e albini p., 2000. quanti terremoti abbiamo perso nell’ultimo millennio? in galadini, meletti & rebez (editors), le ricerche del gndt nel campo della pericolosità sismica (1996-1999), cnrgndt, 333-343. 167analisi archeosismologiche nel santuario ... ms. ricevuto il 6 marzo 2002 testo definitivo ricevuto il 4 giugno 2002 ms. received: march 6, 2002 final text received: june 4, 2002 imp. dirita-magri ppoolllleenn aannaallyyssiiss ooff uuppppeerr pplleeiissttoocceennee sseeddiimmeennttss aatt ccaammppoo ffeelliiccee,, cceennttrraall iittaallyy ffeeddeerriiccoo ddii rriittaa11 && ddoonnaatteellllaa mmaaggrrii11 1dipartimento di biologia vegetale, università “la sapienza”, p.le aldo moro, 5 – 00185 rome, italy. abstract: di rita f. & magri d., pollen analysis of upper pleistocene sediments at campo felice, central italy. it issn 0394-3356, 2004. the pollen record from the lacustrine sediments of the campo felice plain (abruzzo, central italy) provides the first palaeovegetational data for the mountain belt of the central apennines during the upper pleistocene. the estimated age of the record is 90,000 years, based on the biostratigraphical correlation with the other long pollen records from central and southern italy. a wooded period at the base of the diagram is correlated with the forest phase st germain ii ss..ll.., while a long time interval of steppe vegetation in the upper part of the record is assigned to the last glacial maximum. the presence, appearance or disappearance of tree taxa (juniperus, pinus, fagus, abies, picea and betula) in the region is inferred from the features of the pollen diagram, which provides also information on a number of lake-level oscillations and sedimentological events. riassunto: di rita f. & magri d., analisi polliniche di sedimenti del pleistocene superiore a campo felice, italia centrale. it issn 0394-3356, 2004. il diagramma pollinico della piana di campo felice (abruzzo) fornisce i primi dati paleovegetazionali per la fascia montana degli appennini centrali, al di sopra di 1500 m, durante il pleistocene superiore. l’età stimata della base della sequenza pollinica, correlata stratigraficamente con altri diagrammi dell’italia centrale e meridionale, è di circa 90.000 anni: un periodo con vegetazione arborea alla base del diagramma è correlato con la fase forestale st germain ii s.l., mentre un lungo intervallo di tempo con vegetazione steppica nella parte superiore del diagramma è interpretato come coevo dell’ultimo massimo glaciale. la presenza, comparsa o scomparsa di alcuni taxa arborei (juniperus, pinus, fagus, abies, picea e betula) nella zona di campo felice vengono ricostruite a partire dal diagramma pollinico, che fornisce anche alcune informazioni su cambiamenti dei livelli lacustri ed eventi sedimentari. keywords: pollen, upper pleistocene, apennines, abruzzo. parole chiave: polline, pleistocene superiore, appennini, abruzzo. il quaternario italian journal of quaternary sciences 1177(1), 2004, 117-127 11.. iinnttrroodduuccttiioonn the palynological study on the campo felice plain is part of a programme of palaeoenvironmental investigations carried out in central italy within a special project of cnr, bringing together researchers in the fields of geology, geomorphology, sedimentology, mineralogy, geochemistry, palaeontology and palynology to study the quaternary palaeoclimate as recorded in continental successions. this work complements the geological and geomorphological investigations already carried out in the area (giraudi, 1998; 2001), with the aim of providing new insights into the evolution of the campo felice palaeolake and surrounding landscape. it represents the first palynostratigraphical investigation at high elevation on the central apennines, offering new elements for a better comprehension of the vegetation dynamics in the mountain sectors of central italy, which proves to be rather different from that of middle and low elevations sites at the same latitude. 22.. tthhee ssiittee 22..11.. ggeeoollooggyy aanndd ggeeoommoorrpphhoollooggyy the campo felice plain (fig. 1), located at an altitude between 1520 and 1600 m (lat 42°13’n, long 13°27’e), occupies the ground of a closed basin of tectonic origin situated in the northern portion of the mt velino massif. its catchment basin, covering a surface area of about 40 km2, extending for large stretches above 2000 m and reaching 2271 m at vena stellante, is represented by meso-cenozoic limestone ridges (accordi et al., 1986). the tectonic origin of the plain is documented by an important fault, probably active during the holocene, oriented nw-se in the eastern portion of the plain (the mt cefalone fault) and wnw-ese in the western portion (the mt orsello fault), displacing a limestone monocline raising at the northern edge of the plain. the movement of this fault truncated a valley whose head, lying between mt cefalone and mt serralunga, is represented by the forcamiccia pass. this valley, that was one of the main outflow ways of the campo felice basin, was possibly partly covered by the sediments of campo felice. in fact, the survey of two deep boreholes in the plain, in front of the forcamiccia pass, suggests the existence of the valley underneath the quaternary cover (giraudi, 1998). lacustrine terraces and ridges, between 1527 m and 1540 m, suggest for this basin lake level oscillations of nearly 13 m during the last 30,000 years, which are believed to have been mainly produced by climatic factors, in spite of the presence of small ponors in the plain (giraudi, 2001). 118 f. di rita & d. magri most of the sediments outcropping on the plain represent deposits of glacial, fluvioglacial, alluvial, lacustrine, and aeolian origin, datable to the upper pleistocene and holocene (giraudi, 2001). in a few restricted portions of the plain, more ancient glacial and detritic sediments are found, probably of middle pleistocene age (giraudi, 1998). an extensive area of the basin (cento monti) is occupied by morains and fluvial sediments, dividing the plain into an eastern and a western portions, where two distinct lacustrine basins were located. the present study deals with the lacustrine sediments of the eastern portion (fig. 1), that was occupied by the widest lacustrine body and was fed by a catchment basin of nearly 24 km2. 22..22.. pprreesseenntt cclliimmaattee aanndd vveeggeettaattiioonn no meteorological stations are found in the campo felice plain, providing direct measures for the current temperature and precipitation values. a station working at rocca di mezzo, a few kilometers away at an altitude of 1329 m, recorded a mean annual temperature of 8˚c in the time span of 30 years (ministero lavori pubblici, 1959-1989); this value is supposedly somewhat higher than in the plain, which lies at a higher elevation. the mean annual precipitation recorded at rocca di mezzo during the same time period is 1013 mm (ministero lavori pubblici, 1959-1989). the mean annual precipitation at campo felice may be estimated as approx. 1300 mm (boni et al., 1986). the campo felice basin has never been the subject of detailed and specific botanical studies, but phytogeographic information is available for the nearby massifs of mt velino (avena & blasi, 1980) and mt sirente (veri & tammaro, 1980). the modern vegetation of campo felice is represented by four main features: pastures, beech forest, shrubland and grasslands above the tree-line. the grass-covered ground represents the main vegetational landscape of the campo felice plain, including both the mountain pastures and the grasslands above the tree-line. the mountain pastures extend over most of the quaternary sediments outcropping on the plain. beech represents the main natural arboreal component at campo felice, where it lives at an altitude from 1550 m to above 1800 m. the beech wood most likely belongs to the typical polysticho-fagetum phytosociological association, assessed for the inland regions of the central apennines. this association was also observed on the mt velino (petriccione, 1993) and mt sirente (veri & tammaro, 1980) massifs. the shrubland is mostly costituted by juniperus communis, subsp. alpina (suter) celak. other important species are: daphne oleoides schreber, arctostaphylos uva-ursi (l.) sprengel, cotoneaster nebrodensis (cuss.) c.koch, rhamnus alpinus l., rosa rubrifolia vill., rosa pendulina l., rosa montana chaix, and chamaecytisus spinescens (presl) rothm. (blasi et al., 1990). the shrubland is generally found above the forest, and reaches an altitude of 2300 m. however on the mt velino massif, because of deforestation for pastures, it is situated at much lower elevations, potentially belonging to the forest vegetation belt (blasi et al., 1990). in the campo felice area the shrub woodland is located both above and just below the beech forest, where juniperus forms very wide and dense blankets. above the shrubland, grassland is the dominant vegetational element, characterized by sesleria tenuifolia schrader, gentiana lutea l., pulsatilla alpina (l.) delarbre, festuca violacea gaudin, luzula italica parl., and plantago atrata hoppe. (avena & blasi, 1980). 33.. mmaatteerriiaallss aanndd mmeetthhooddss 33..11.. ccoorriinngg aanndd lliitthhoossttrraattiiggrraapphhyy a number of sediment cores were collected from fig. 1 -– schematic geological map of the eastern portion of campo felice (simplified from giraudi, 1998). 1. meso-cenozoic bedrock, 2. lacustrine sediments, 3. moraines, scree, breccia, 4. alluvial fans, 5. frontal moraine, 6. lacustrine beach ridge, 7. fault active during the quaternary, 8. location of core cf7. carta geologica schematica della porzione orientale di campo felice (semplificata da giraudi, 1998). 1. substrato meso-cenozoico, 2. sedimenti lacustri, 3. morene, detrito di falda, breccia, 4. conoidi alluvionali e fluvioglaciali, 5. morene frontali, 6. cordone litorale lacustre, 7. faglia attiva nel quaternario, 8. localizzazione del sondaggio cf7. the lacustrine plain of campo felice in septembernovember 1997. the upper 47 m of the core named cf7, the deepest core (123 m) in the eastern portion of the plain, located just in front of the forcamiccia pass (fig. 1), have been the subject of the present palynological work. the recovered lacustrine sediments mainly consist of whitish or light brown calcareous silts, intermixed by volcanic, fluvial, organic sediments and palaeosols (giraudi, 1998). in particular, the sediments of core cf7 indicate a drying of the lake at 27.0-21.6 m where paleosols are found. at 43-42 m there is a level of dark organic sediments. from 47 m to ca. 30 m, the lacustrine sediments are frequently very rich of volcanic materials (giraudi, personal communication). 33..22.. ppoolllleenn aannaallyyssiiss the samples for pollen analysis have been selected and prepared at ca. 1 m interval from the top of the core down to 32 m and mostly at 20-30 cm interval from 32 m to 47 m, where arboreal pollen is more abundant. a total of 96 samples was analysed. they were dried and then chemically treated with hcl (37%), hf (40%) and naoh (10%), with the aim of reducing the detrital sediments and concentrate the pollen grains. a few samples, presenting volcanic ashes even after the chemical treatment, were sieved to eliminate the particles coarser than 250 µm and finer than 7 µm. pollen concentration values were estimated by adding lycopodium tablets to known weights of dry sediment. in all, only 55 samples presented concentration values suitable for pollen counting and representation on the pollen diagrams. in the 3 samples where arboreal pollen (ap) exceeds 50% the mean count was 470 terrestrial pollen grains; while in the 52 samples with more than 50% non-arboreal pollen (nap) the mean count was 199 terrestrial pollen grains. the preservation of the pollen grains was generally modest, the mean percentage of indeterminable grains per sample (degraded, corroded and broken) is 8%. excluding the spores, 59 pollen taxa have been identified, the highest number of taxa per sample being 36 and the lowest 9. according to the morphological characters of quercus pollen described by van benthem et al. (1984), two pollen types were distinguished, deciduous and evergreen quercus. the pollen type named ostrya type includes both ostrya carpinifolia and carpinus orientalis. 44.. rreessuullttss 44..11.. tthhee ppoolllleenn ddiiaaggrraamm the results of the pollen analysis are represented in fig. 2. local pollen zones, defined by subjective zonation, are indicated by the site designation prefix cf followed by core number 7, and are numbered from the base upwards. five pollen zones have been defined. zone cf7-1 (46.57-41.70 m) this zone represents a wood expansion, with maximum ap percentages of 64% at the top of the zone. total pollen concentrations are very disomogeneous, ranging from 900 to over 1,600,000 grains/g. abies is the most important tree taxon. several arboreal taxa reach the highest percentage values of the sequence, although not all at the same depth: alnus (2%) at 46.57 m, deciduous oaks (3%) at 119pollen analysis of upper pleistocene ... 44.55 m, ulmus (2%) at 44.05 m, corylus (1.5%) at 43.25 m, fagus (5%) at 43.25 m, abies (26.5%) at 43.05 m, and picea (9%) at 42.85 m. this succession clearly indicates a forest dynamics with elements of mixed oak forest at the beginning, followed by montane tree taxa (beech and fir) and finally by spruce, as it is commonly observed in many european pollen records in the course of an interglacial cycle (birks, 1986). several ap taxa are sporadically present, with percentages <1%: fraxinus, tilia, salix, betula, populus, and zelkova. pinus shows values of 5-12%, which may not indicate a significant local distribution of pine, whose pollen is frequently over-represented in the pollen diagrams. among the herbs, very high percentages of cichorioideae (max. 66%) are recorded at the base of the zone. gramineae (max. 21%), artemisia (mostly 57%) and caryophyllaceae (5%) are also well respresented. zone cf7-2 (41.70-36.67 m) this zone is characterized by sparse presence of deciduous trees pollen, never reaching 2% altogether. two arboreal taxa show important values: pinus, with a peak of 37% at 41.05 m, is the dominant tree in the lower half of the zone, and juniperus, with a sharp peak of 39% at 38.25 m, is the dominant element in the upper part of the zone. among the other gymnosperms, only picea (4%) and ephedra fragilis type (3.5%) at 38.67 m reach appreciable values. the pollen concentration of ap is generally low, except for pinus (with a peak of over 17,000 grains/g) and juniperus (over 12,500 grains/g). herbs are very abundant and diversified: artemisia is the most important nap taxon, increasing from 23% at 41.55 m to 62% at 37.35 m. other important nap are: cichorioideae (220%, with a single sharp peak reaching 44%), gramineae (max. 10%), asteroideae (max. 7%), chenopodiaceae (max. 6%) and thalictrum (max. 3.5%). zone cf7-3 (36.67-34.23 m) this is a new moderate wood expansion, although less important than in zone cf7-1, as ap percentages reach 46%. pollen concentrations range between 3000 and 45,000 grains/g. abies is the most important tree taxon, peaking 18.5% at 35.18 m. other significant tree taxa are: picea, showing a peak (8.7%) at 34.58 m, fagus (3%), quercus (1.8%). moreover, a number of arboreal taxa are present with very low percentages, including zelkova, with its most recent appearance at 35.08 m. similarly to zone cf7-1, in zone cf7-3 it is possible to recognize a pattern of forest dynamics with different trees expanding one after the other: first deciduous quercus peaking at 36.57 m, then fagus, carpinus betulus, populus and abies at 35.18 m, and finally picea at 34.58 m. among the herbs, cichorioideae are very abundant, together with gramineae and artemisia. zone cf7-4 (34.23-32.05 m) this zone is characterized by high nap values. boadleaved trees do not reach 3% altogether. pinus and juniperus are the only arboreal taxa continuously present. in the lower part of the zone there is a very pronounced peak of artemisia (57%), accompanied by cichorioideae (7%); in the upper part of the zone an increase of cichorioideae (up to 40%) corresponds to a decrease of artemisia (max. 120 22 aa )) f. di rita & d. magri 121 f ig . 2 – p o lle n d ia g ra m o f c a m p o f e lic e . d ia g ra m m a p o lli n ic o d i c a m p o f e lic e . 22 bb )) pollen analysis of upper pleistocene ... 122 20%). other significant nap are asteroideae, gramineae and caryophyllaceae. the mean pollen concentration is 7300 grains/g. the sediments between 32.05 m and 21.82 m have very low pollen concentrations. for this reason the pollen counts cannot be adequately represented on the diagram, that is interrupted even if the sediment core is available. zone cf7-5 (21.82-5.04 m) – this zone represents a period dominated by herbaceous taxa with only very sporadic apparences of broadleaved trees. the mean ap percentage value is around 20%, including pinus and juniperus, that are the only important arboreal taxa. ephedra fragilis type shows appreciable values, reaching 5% at 21.82 m. the whole zone is characterized by a considerable abundance of artemisia, which is the dominant taxon (always >44% with a peak of 68% at 14.94 m). gramineae (max. 16%) and chenopodiaceae (max. 10%) are also important nap. the pollen concentration values are generally very low, being comprised between 800 and 6150 grains /g. 55.. ddiissccuussssiioonn the interpretation of the floristic data and vegetational dynamics recorded in the pollen diagram cannot omit consideration of the geographic characters of the campo felice plain, in particular of its elevation, above 1500 m a.s.l., which also at present is the main factor affecting the vegetation. 55..11.. vveeggeettaattiioonn cchhaannggeess the time period recorded by the pollen diagram of campo felice shows two distinct vegetational phases each characterized by a significant floristic renewal, deeply changing the landscape: zones cf7-1 to cf7-3 display a certain expansion of arboreal vegetation while zones cf7-4 and cf7-5 are typified by steppe and grassland diffusion. zone cf7-1 represents a vegetational phase characterized by a relatively high number of arboreal taxa (22), even if ap exceeds 50% only in the sample at 43.05 m, where also the pollen concentration is high (>600,000 grains/g). as modern palynological studies indicate that real forest conditions are associated to ap percentage values of at least 75% (reille, 1975), zone cf7-1 cannot be considered a real forest phase, with dense tree cover. however, considering the high elevation of the site, which does not allow even at present a full forest expansion, and the clear vegetation dynamics showing a succession of peaks of deciduous tree taxa and conifers, this zone is certainly indicative of dense tree cover at lower elevations. zone cf7-3 is characterized by a number of arboreal taxa (both conifers and broadleaved trees) similar to zone cf7-1, but with lower ap percentages (max 46%), due to generally lower values of abies, fagus, and floristic elements belonging to the “quercetum mixtum”, such as deciduous oaks, carpinus betulus and ulmus. also in zone cf7-3 a clear succession of arboreal taxa, presently belonging to different vegetational belts, can be recognized, starting with few grains of deciduous quercus, living nowadays at an altitude lower than at campo felice, followed by fagus and abies, and finally by picea, which is presently found on the alps beetwen 1000 and 1900 m (pignatti, 1982). this vegetation dynamics is therefore characterized by a progressive diffusion of mountain arboreal taxa, ending with an open vegetation with juniperus and pinus in zone cf7-4. zones cf7-1 and cf7-3 are separated by a period (zone cf7-2) with steppe and grassland diffusion. ap percentages do not undergo a substantial decrease, as juniperus and pinus maintain high values. this zone displays a decrease of deciduous trees and abies and an increase of artemisia and other herbaceous taxa, such as chenopodiaceae, that altogether are typical components of the cold and arid steppes of the pleistocene glacial stages. this vegetation type is also characteristic of zones cf7-4 and cf7-5, when the presence of deciduous trees and fir is further reduced to very rare appearances. very high percentage values of artemisia, gramineae and chenopodiaceae are presently found both in arid regions with very cold winters (e.g. in the mountainous regions of armenia) and in arid areas between desert and mediterranean vegetation in northern africa, where winters are generally mild. in both cases, the dryness of climate appears to be the main limiting factor for tree growth. 55..22.. fflloorriissttiicc ddiivveerrssiittyy a comparison with the present-day flora of the campo felice area may help in defining which taxa have been continuously present in the vicinity of the site and which have immigrated or disappared from the area. apart from grasses, which are abundantly found throughout the diagram and also at present form the main vegetation type of the campo felice plain, it is worth mentioning the presence of juniperus pollen type in all the samples of core cf7, both in the periods with woody vegetation and with open vegetation. this indicates that the modern abundance of juniperus, representing one of the main vegetational elements of the plain both above and below the beech wood belt, has a long history of local persistence, and that the geographic and climatic features of campo felice have been particularly favourable for the maintenance and development of juniper. another taxon which is continuously well represented in the pollen diagram is pinus, which is however very rare in the modern flora of the area. this abundance can reasonably be interpreted as long distance transport, as pine is a huge pollen producer and its pollen is conspicuously found also in all the other italian pollen records (e.g. follieri et al., 1988; watts et al., 1996; magri, 1999; magri & sadori, 1999). the modern diffusion of fagus around the campo felice plain can be shown to be relatively recent. in fact, while beech is present in zones cf7-1 and cf7-3, with values always <6%, it completely disappears in zones cf7-4 and cf7-5. this suggests that the modern beech wood was most likely reintroduced in the course of the postglacial forest expansion, migrating from refuge areas which were presumably located at lower elevations, as indicated by the more or less continuous pref. di rita & d. magri sence of beech at other sites of central italy (follieri et al., 1998). in the pollen diagram from campo felice three pollen taxa are recorded that have presently a broken distribution in central italy: abies, picea and betula. the history of the distribution of these genera during the late quaternary has been highlighted in the palynological works from central italy, including valle di castiglione (follieri et al., 1988), lagaccione (magri, 1999), lago di vico (magri and sadori, 1999), stracciacappa (follieri et al., 1998), and lago lungo near rieti (calderoni et al. 1994). abies alba mill., is the only fir species occurring in the italian peninsula; it is found on the alps, on the southern appenines, and at a few isolated sites on the central and northern appenines (quezel, 1980). in the abruzzo region abies is presently found as a relic, associated with fagus in a few beech-wood stands of very cold sites in the teramo province (zodda, 1967; longhitano & ronsisvalle, 1974). the long pollen records from central italy show that fir was very rare during the eemian, corresponding to marine isotope stage (mis) 5e, while it characterized both the st germain periods which are the last forest phases before the postglacial (mis 5d and 5a) (follieri et al., 1998). after these forest phases, abies pollen is only sporadically recorded, probably from far origin. in fact, abies is continuously represented in pollen diagrams from both southern italy, at lago grande di monticchio in basilicata (watts, 1985; watts et al., 1996), at canolo nuovo in calabria (grüger, 1977), and in a marine core from the tyrrhenian sea (rossignol strick and planchais, 1989), and from northern italy in the apennines (bertoldi, 1980; lowe and watson, 1993; watson, 1996). these pollen data show that the present-day broken distribution of abies is the result of a strong reduction occurred during the last pleniglacial especially in central italy. at campo felice abies shows the typical trend of the other sites from central italy, being an important tree taxon during the wood expansions of zones cf7-1 and cf7-3, and disappearing during the open vegetation zone cf7-5. picea is one of the most characteristic taxa of the campo felice record. according to the present-day pollen-vegetation relationships (huntley & birks, 1983; hicks, 1994), pollen percentage values higher than 5% indicate a local presence of picea. in the campo felice record seven samples show values of spruce above this percentage threshold. in particular, two peaks of picea (attaining 9%) are recorded in zones cf7-1 and cf7-3, indicating that this taxon was one of the main floristic elements of the wooded landscape at the end of the arboreal succession. the late-quaternary history of picea in central italy starts with a spread at the end of the st germain ii forest phase (mis 5a) in all the pollen sites of the lazio region, where a second increase took place during the middle pleniglacial interstadials (follieri et al., 1998). the modest percentage values recorded around 20,000 bp at lago di vico and stracciacappa represent the last expansion of this taxon in the region. in the pollen record from lago grande di monticchio, in basilicata, picea is not recorded (allen et al., 2000). the presence of picea pollen in zones cf7-1 and cf7-3, even if in low percentages, is very remarkable, as its present geographic distribution is very northern: in italy picea abies (l.) karsten lives only on the alps and in very few relic stations in the northern appennines (pignatti, 1982; jalas & suominen, 1973). the sites from lazio provide evidence that, from about 80 ka to 20 ka, the geographical distribution of spruce was definitely more southern than at present. the campo felice record, where picea percentage values are the highest of central italy probably in relation to the high elevation of the mountain ranges, confirms that spruce was also diffused in the abruzzo region. sporadic pollen grains of betula are recorded in 5 samples of zones cf7-1 and cf7-2, never attaining 1%. at present, birch has its range-bulk centered at northern latitudes in europe, but is also present at scattered sites of the italian peninsula (spada et al., 1995). in the abruzzo region small stands of few individuals of betula pendula roth. are found in a few restricted mountain areas. two main hypotheses have been advanced to explain this distribution: agostini (1981) suggests that the present geographic distribution of birch in the italian peninsula is the result of a migration from more northern latitudes during the last pleniglacial. on the contrary, spada et al. (1995) consider the present-day scantiness of birch on the apennines as resulting from an extreme fragmentation of a previously more continuous range, due to reiterated dryness of climate during the quaternary glacial cycles. even if it is impossible to state whether the birch pollen of the campo felice diagram was produced by very sparse trees living in the landscape in the vicinity of the lake or by larger stands at a distant location, it clearly appears that the open vegetation of the upper part of the diagram, which is typical of the glacial phases of the quaternary, was unfavourable for the development of betula populations, and that, in the time span recorded by the diagram, there is a general trend towards a decrease of betula, supporting the hypothesis by spada et al. (1995). finally, a taxon is recorded at campo felice which is extinct in the italian peninsula but is present as a relict in sicily (di pasquale et al., 1992). zelkova characterizes the eemian interglacial (mis 5e) at valle di castiglione (follieri et al., 1986). it is continuously recorded during the st germain i and ii forest periods (mis 5d and 5a), but it became rare during the pleniglacial interstadials (mis 3), when it eventually disappared (follieri et al., 1998). a few pollen grains of zelkova are recorded at campo felice in four samples of zones cf7-1 and cf7-3. although these sporadic findings are most likely of far geographic origin, as zelkova is a thermophilous tree, they take on a special value as they may represent an important chronological reference ante quem. 55..33.. bbiioossttrraattiiggrraapphhyy as no radiocarbon data are available for the cf7 core, the chronostratigraphical interpretation of the record can only be based on a comparison of the floristic and vegetational features of the campo felice pollen diagram with the long records from central and southern italy which have an own chronostratigraphical setting. the records from valle di castiglione near rome (follieri et al., 1988), lago di vico (magri & sadori, 1999), lagaccione near lago di bolsena (magri, 1999) and lago grande di monticchio in basilicata (watts et al., 1996, watts et al., 2000, allen et al., 2000) 123pollen analysis of upper pleistocene ... may be particularly useful, even if they are located at much lower elevations (0-700 m a.s.l.) based on the assumption that the studied stretch of core cf7 does not include hiatuses as long as hundred thousand years, the zones at the base of the record, where woodland dominates the landscape, should most likely be correlated with the last forest expansions before the postglacial, that is with phases corresponding to substages of mis 5. however, a correlation with the eemian interglacial (mis 5e) can be definitely excluded, as this was characterized by very termophilous vegetation (follieri et al., 1988), not represented in core cf7. instead, it seems resonable to assign the wooded pollen zones cf7-1 and cf7-3 to the two st germain forest phases (roughly corresponding to mis 5c and 5a, respectively), or with one of the two. the floristic and vegetational features of the st germain periods recorded in the long records of central italy may constitute the basis for this assignment. the st germain i forest period is characterized, both at valle di castiglione (follieri et al., 1988) and at lagaccione (magri, 1999), as well as at lago grande di monticchio (allen et al., 2000) by deciduous oaks and fagus, as the main components of the vegetation, accompanied by carpinus and ulmus. at the end of this forest expansion, abies attains very high percentage and concentration values. the following non-forested phase (melisay ii, mis 5b) is dominated by chenopodiaceae, with very high percentages, not only in the italian sites (valle di castiglione, lagaccione and lago grande di monticchio), but also in other sites of southern europe, such as kopais (tzedakis, 1994) and tenaghi philippon (wijmstra, 1969). the st germain ii sensu lato forest period (fig. 4) is well-represented in the lazio region at lagaccione (magri, 1999) and at lago di vico (magri & sadori, 1999) and partly recorded at valle di castiglione (follieri et al., 1988). in these sites the st germain ii is characterized by two forest oscillations, locally named etruria i and etruria ii, followed by a third minor oscillation (etruria iii) (magri & sadori, 1999). they are separated by two periods in which trees are continuously present, although clearly reduced, as only pinus shows high percentage values. the first two forest phases (etruria i and ii) display very similar vegetation dynamics, starting with deciduous oaks and corylus, followed by an expansion of fagus and carpinus betulus, and ending with an increase of abies, while the third arboreal oscillation (etruria iii) is clearly distinct due to the dominance of deciduous oaks, accompanied by many trees in low percentages, and to the increase of picea, which during the st germain i had very low values. two hypotheses may be advanced to define the biostratigraphical setting of zones cf7-1 and cf7-3. on the basis of the importance of abies, they can be correlated either with st germain i and st germain ii, respectively, or with two different fluctuations of the st germain ii sensu lato forest period. a correlation of zones cf7-1 and cf7-3 with st germain i and st germain ii, respectively, would imply that they are considered to be two remarkable and well distinct wood expansions, separated by a very harsh steppe environment. the presence of picea in zone cf7-1 would not match the floristic characters of st germain i highlighted by the other sites of central italy, where picea pollen is abundantly recorded only during the st germain ii and it is almost absent during the st germain i. the features of the campo felice wood phases correspond to two moderate diffusions of arboreal vegetation separated by a steppe phase in which the elements of the deciduous woodland do not completely disappear and conifers are well represented (fig. 3). for this reason a correlation of zones cf7-1 and cf7-3 with etruria i and etruria ii, respectively, appears much more convincing than a correlation with st germain i and st germain ii. in fact, in the campo felice record, the open vegetation phase (zone cf7-2) between the two wood124 fig. 3 – correlation of the pollen diagrams from lagaccione (magri, 1999), lago di vico (magri & sadori, 1999) and campo felice for the etruria forest phases (partly redrawn from magri & sadori, 1999). correlazione dei diagrammi pollinici di lagaccione (magri, 1999), lago di vico (magri & sadori, 1999) e campo felice per le fasi forestali etruria (in parte ridisegnato da magri & sadori, 1999). f. di rita & d. magri land periods is not as marked as in the melisay ii, between st germain i and st germain ii, in the other long european pollen records. the abundance of picea in zone cf7-1, typical of st germain ii in central italy, is a further evidence in favour of this correlation. the main difference between the wooded zones in the cf7 record (cf7-1 and cf7-3) and those of the coeval other long records from central and southern italy is the scantiness of fagus, which was clearly much more abundant at lower elevations, for example lagaccione (355 m; magri, 1999), lago di vico (510 m; magri & sadori, 1999), and lago grande di monticchio (656 m; allen et al., 2000) than at the high mountain sites. in the long italian records (follieri et al., 1998; allen et al., 2000), soon after the st germain ii there is a steppe phase with no arboreal taxa, excepting pinus and juniperus, corresponding to mis 4, followed by a number of more or less weak forest oscillations corresponding to mis 3, and finally by very marked steppe vegetation during mis 2, before the lateand postglacial reforestation. zone cf7-5 can be easily correlated with the last pleniglacial period, that everywhere in europe is characterized by open vegetation with very high percentage values of artemisia, pinus and gramineae and very low pollen concentrations. also the upper part of the campo felice diagram is represented by samples with very low pollen concentration, indicating a very poor open vegetation, dominated by artemisia, pinus, juniperus, gramineae and chenopodiaceae, and almost lacking in deciduous trees. the floristic features of this period at campo felice are not distinctive enough to individuate the pleniglacial interstadials of mis 3. this may be due either to the high elevation of the site, which did not allow any tree population expansion during those short climate oscillations, or to a lack of record, if the pleniglacial interstadial are chronologically correspond to the sediments from 32 m to 22 m, where the diagram is interrupted. anyway the stratigraphical position of the lacking record would suggest that this could include the sediments corresponding to the middle pleniglacial interstadials. on the basis of these biostratigraphical considerations, the approximate age of the base of zone cf7-1 can be estimated as 90,000 years, that is the age of the beginning of the st germain ii forest period, supported also by the 87±7 ka old ar/ar date of a tephra layer at the base of st germain ii at lago di vico (magri & sadori, 1999). by comparison with the age model proposed for the lago grande di monticchio record (allen et al. 2000), the top of zone cf7-3 may be estimated as approximately 75,000 years old. while it is difficult to define the age of the sediments poor in pollen between 32 m and 22 m, zone cf7-5 can be reasonably assigned to mis 2. holocene sediments, characterized everywhere in italy and southern europe by a rich forest vegetation, are not represented in the cf7 pollen diagram. 55..44.. ppoolllleenn aanndd llaaccuussttrriinnee sseeddiimmeennttaattiioonn the long pollen record of campo felice provides some useful elements for interpreting the sedimentological events occurred in the lacustrine basin of the eastern portion of the plain. the lower part of the cf7 diagram (zones cf7-1 and cf7-3) presents a series of considerable peaks of pollen of cichorioideae. this is often abundant in paleosols or in oxydized sediments, such as cultural layers from caves (bottema, 1975), as it is very resistant to corrosion and its typical morphology can be easily recognized even in deteriorated grains. for this reason high dominance of cichorioideae percentages may be due to differential preservation of pollen grains and may have no value as indicator of steppe or other open vegetation (havinga, 1984). similar resistance has been observed in lycopodium and polypodium spores (havinga, 1984). abundant trilete and monolete spores are recorded in zone cf7-1. in the same levels, very rich in detrital sediments of volcanic origin, significant amounts of pseudoschizaea, a bilaterally-symmetrical cell with finger-print-like concentric striations (christopher, 1976; scott, 1992), are recorded. this taxon is considered to be a good indicator for increased soil erosion and possibly also for running water (pantaleón-cano et al., 1996). the contemporary abundance of cichorioideae, pseudoschizaea and spores in zone cf7-1 brings evidence for erosional phases in the catchment basin, possibly accompanied by lowerings of the lake level. several reasons can explain why the sediments between 32 m and 22 m depth are very poor in pollen, including a very scarce pollen production due to sparse vegetation, very fast sediment accumulation rates, drying of the lake, or severe pollen deterioration. in fact, a combination of all these factors may have also occurred, with a drastic lowering of the lake, preventing the conservation of the few pollen grains produced by an open vegetation. this interpretation is also supported by the presence of palaeosols between 23.7 m and 21.0 m depth in core cf7. the stratigraphical position of this stretch of core, between st germain ii and the last glacial stage (corresponding to mis 2) would indicate for this pollen hiatus an age corresponding to mis 3 and maybe part of stage 4. the zone cf7-5, corresponding by and large to the last glacial maximum, shows a continuous and wellrepresented pollen record, with no evidence for important lake lowerings. this result is in agreement with the high level stand demostrated for the campo felice lake by a terrace at 1540 m assigned to mis 2 (giraudi, 2001), and also with the general state of many lakes around the mediterranean region, reaching their highest levels during the last glacial maximum (giraudi, 1989; bartov et al., 2002). 66.. ccoonncclluussiioonnss the pollen record from campo felice offers new insights for a better understanding of the vegetation dynamics occurred in the mountain areas of central italy during the upper pleistocene. in fact, this study represents the first palynostratigraphical investigation at an elevation of over 1500 m a.s.l. in central italy. the chronological interpretation of the record indicates that the age of the sediments at 47 m in core cf7 is approx. 90,000 years. the floristic characters of the lower part of the diagram is correlated with two oscillations of the st germain ii forest period, recorded at four other sites in italy at lower elevations. the upper part of the cf7 diagram is correlated with the last glacial maxi125pollen analysis of upper pleistocene ... mum, characterized by steppe vegetation, as in most of southern europe. several vegetational features of the campo felice plain can be interpreted as an effect of the high elevation of the site, in particular the considerable abundance of juniperus, a taxon always present in the site throughout the last 90,000 years, the infrequency of deciduous tree taxa even during the main wooded phases, the sparse vegetational cover during the last pleniglacial, when campo felice was covered by ice sheets, as documented by the geomorphology of the site (giraudi, 1998; 2001), the significant amount of picea, a tree that during the last glacial period occupied a much more southern position than at present, finding favourable conditions for its growing on the abruzzo mountains. the low abundance of fagus during the wooded zones of the diagram (cf7-1 and cf7-3) is rather unexpected, as nowadays beech represents the main floristic element of the campo felice arboreal cover and is generally the most important tree of the mountain belt of the apennines. a comparison with the other sites in central and southern italy indicates that during the st germain ii phase beech dominated a densely covered vegetation belt at a lower elevation, while the areas over 1500 m were occupied by a more sparse vegetation, in which the most important trees were represented by conifers (abies, picea, juniperus, and pinus). juniperus is currently the only remnant of this vegetation type. the results obtained through this palynological study show that the campo felice plain and the mountain areas of the central apennines deserve further attention. the multidisciplinary integration of geomorphological and sedimentological data with the cf7 pollen record, set in the palynostratigraphical framework established for central italy, allows some inferences to be made on the palaeoenvironmental evolution of the basin and on the reconstruction of lake level variations in relation to climatic events of the upper pleistocene. besides, it would be important to support the chronology of the most significant biostratigraphical events the cf7 core by other sources of evidence, and to study through pollen analysis other sediment records from the campo felice plain. aacckknnoowwlleeddggeemmeennttss we thank maria follieri, carlo giraudi and biancamaria narcisi for their helpful comments on the 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(1967) compendio della flora teramana. archivio botanico e biogeografico italiano, 4433, 35101. 127 ms. ricevuto il 20 febbraio 2004 testo definitivo ricevuto il 6 aprile 2004 ms. received: february 20, 2004 final text received: april 6, 2004 pollen analysis of upper pleistocene ... ojs 591 sigari forti proof copy corretta.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 35 (2), 2022, 1-14 1. introduction 1.1. prehistoric rock art and landscape in the last 30 years, the study of the rock art context has become a main topic of investigation (bourdier & fuentes, 2015; bourdier et al., 2017; chippindale & nash, 2004; clottes, 1993a, 1993b; jouteau et al., 2019, 2020; nash & chippindale, 2002; ochoa & garcía -diez, 2018; ortega martínez, 2014; rodríguez-rellán & fábregas valcarce, 2016; sacchi, 1999; sakamoto et al., 2020). beyond the stylistic and chronological aspects, the attention paid to the analysis of the spatial features has permitted to get into different dimensions of rock art, including social, economic, ritual, cognitive, functional, taphonomic and ecological (bourdier, 2013; chippindale & nash, 2004; fairén-jiménez, 2008; mcdonald, 1998; nash, 2011; sigari, 2022; sognnes, 1998; walderhaug, 1998). together with portable art, rock art is the main source to approach non-literate societies in terms of cultural systems and provides a key tool for any archaeological and anthropological research to assess how ancient cultures responded to environmental change. indeed, it is part of dynamic systems that involve both the changes in the environmental context and the cultural relationships of the populations that chose the site and signified it, acting within the landscape and the site itself, and making rock art (arsenault, 2004; bourdier, 2013; hartley & wolley vawser, 1998; hyder, 2004). within the dynamic relationship between the artist/ viewer and the physical environment, where the rock art is placed, several studies have been investigating at both macro and micro-scales, focusing on the relationships with the environment, topography and rock properties (see: chippindale, 2004; gjerde, 2006). differently, other studies have approached the issue of how culturally driven choices might influence rock art locations: being rock art a visual production with strong implications in the communication systems of human groups it may respond to visibility and/or perceptibility reasons (see: bourdier et al., 2017; fossati, 2016; jouteau et al., 2019). within this framework, the open-air rock art contexts are a valid object of study to access the information behind the artistic production, those social and cultural reasons that might have played a role in the selection of the sites and the themes, the use of the territory, and those environmental conditions that influenced the preservation of the rock art evidence. so, the open-air rock art heritage of valcamonica in italy represents a preferential case study to investigate the rock art -landscape-settlements relationships after the last glacial maximum (lgm). https://doi.org/10.26382/amq.2022.05 towards a new perspective on the rock art sites-landscape relations in the upper palaeolithic of valcamonica (n-italy). dario sigari 1,2, luca forti 3 1 cnrs-umr 5608 traces, université toulouse jean jaurès, maison de la recherche, toulouse, france. 2 ispc-cnr istituto di scienze del patrimonio culturale, rome, italy. 3 dipartimento di scienze della terra “ardito desio”, università degli studi di milano, milano, italy. corresponding author: d. sigari <dario.sigari@cnrs.fr> abstract: valcamonica, an alpine valley in northern italy, boasts one of europe’s largest concentrations of open-air rock art that had been produced over millennia, from the upper palaeolithic upto historical times. the richness and the long chronology of its rupestrian heritage pose crucial questions around the dynamic dimension of the rock art sites, according to the geomorphology of the territory and the selection of the rocks to be engraved, in the different chronological phases of the valcamonica human occupation. within the frame of the new research project parc-paesaggi dell’arte rupestre camuna (landscapes of valcamonica rock art), we elaborate a dtm map providing a characterisation of the landscape surrounding those rock art and settlement sites attributed to the upper palaeolithic. this led to the recognition of some features linked to the two site typologies. crossrelating the viewshed projections from luine.034, lcr.006 and cividate camuno hut, we access the intervisibility patterns among the sites, highlighting how the valcamonica territory was conceived as a structured space, and performing a least cost path analysis we propose the optimal path between the living and rock art sites. finally, this first step highlights how the implementation of the available data and the elaboration of parc will provide a useful tool to investigate the dynamic aspects of the prehistoric valcamonica, accessing the relationship with the environment resources, the landscape features and the cultural choices along the different rock art chronologies of the valley, and the taphonomy of the rock art too, favouring the elaboration of preservation plans in the future. keywords: northern italy; rock art; alpine landscape; geomorphology; late pleistocene. 2 sigari d., forti l. 1.2. the valcamonica landscape between the lgm and the holocene the camonica valley, commonly called valcamonica, is a n-s narrow valley located in the rhaetian alps in northern italy. it develops from the headwaters of tonale pass toward the iseo lake in the province of brescia and it is crossed by the oglio river (fig. 1). the valley has a typical u-shape profile that reveals the glacial origin. reconstructions of the palaeolithic landscape of the valley were provided by pini et al. (2016) and ravazzi et al. (2012). according to these authors, during the lgm, the valley was covered by the oglio glacier, which collapsed around 18.5-17.5 ka cal. bp. the deglaciation, with the melting of the ice masses and paraglacial activities, shaped the valley. here, the onset of fluvial networks and slope instability reworked the unconsolidated sediments, and coalescent alluvial fans developed at the outlet of the lateral valleys and at the toeslopes of the valley walls. furthermore, the maximum extent toward n of the iseo lake shore reached the area surrounding cividate camuno. the subsequent climate amelioration of the bølling -allerød interstadial (14.7-12.9 ka cal. bp) led to the development of an open environment characterised by coniferous forest with the timberline located at c. 1,700 m above sea level (a.s.l.), that lowered at 200 m a.s.l. during the younger dryas deterioration (12.8-11.7 ka cal. bp). finally, at the beginning of the holocene the rise of temperature around 4-6°c led to better climatic conditions with the treeline located at 2,400 m a.s.l.. 1.3. valcamonica rock art the human presence in the valcamonica is witnessed by a unique heritage etched in the stone outcrops, with more than 300,000 engraved figures, belonging to a long chronology from the late upper palaeolithic to historical times (anati, 1992; arcà & fossati, 1994; de marinis & fossati, 2012; sigari & fossati, 2021b). the rock art, which is mainly located in the openair, extends for c. 90 km along the whole length of the valley, on both sides with areas of primary clusters, attributed to the three main areas into which the valley space is commonly divided: the lower, mid and upper valley. the rock art of this valley constitutes an archaeological, artistic, ethnographic and historical heritage of inestimable value, inscribed in the unesco world heritage list in 1979, making the valcamonica the first italian site and the first rock art site in the world to have the unesco world heritage site recognition (fossati, 2003). with its open-air rock art and the long chronology of human occupation, the valcamonica cultural heritage reflects human behaviour in giving special meaning and values to certain places that lasted and changed over millennia. understanding how much this attitude had been influenced by the landscape, according to its natural resources richness, visibility, accessibility, location of the rocks and how the cultural variable might have played is a new research field into which the new project parc-paesaggi dell’arte rupestre camuna (landscapes of valcamonica rock art) wants to investigate. the present paper reports the first step of this research project that was focused on those sites that are considered to belong to the most ancient human presence in the valley. specifically, within this work, authors introduce the first results linked to the analysis of the most ancient phase of the valcamonica occupation, including rocks no. 6 and 34 (sometimes respectively named lcr.006 and luine.034, according to their registration code (see: sigari, 2022)) in luine hill and the cividate camuno palaeolithic site (fig. 1), to understand, according to the geomorphology of the vacamonica, if the site locations may respond to visibility reasons, if and how they were crossrelated, and the valley space was culturally conceived by the first human groups that lived the valley. 2. history of rock art studies the rock art of valcamonica was officially discovered at the beginning of the 20th century, thanks to the geographer walther laeng, who found and published the cemmo boulders in capo di ponte (laeng, 1914). fig. 1 (a) location of the valcamonica (yellow) in the italian peninsula located in the southern sector of italian alps (red square). (b) physiographic map with the location of the palaeolithic engraved rocks no. 6 and 34 of luine hill and the cividate camuno hut (map editing: l. forti). 3 valcamonica rock art sites-landscape nexus in the upper palaeolithic in the following decades, thanks to the anthropologists raffaello battaglia and giovanni marro, most discoveries in valcamonica were made. however, only in the sixties and seventies, more attention was focused on the chronology of different phases of rock art, with the studies undertaken by emmanuel anati (anati, 1975), raffaele de marinis (de marinis, 1995), and others. over the last decades, the development of the documentation methodologies and the increasingly collected data have favoured further precision in the chronology of the valcamonica rock art. so, researchers have been investigating the definition of the sociocultural context in which the rock art was produced and the understanding of the meaning of some themes (see: arcà, 2007; arcà et al., 2008; bossoni et al., 2016; de marinis & fossati, 2012; fossati, 1991, 2015; montanari, 2011; sigari, 2016; tognoni, 2007). in particular, the discussion has been focused on the beginning of the 4th style of valcamonica rock art and the attribution of the so-called ‘oranti’, praying figures. finally, in the very last few years, the review of the palaeolithic engravings of luine has led to discuss the concept of the "protocamunnian" style (anati, 1975; sigari, 2022; sigari & fossati, 2021b). indeed, the earliest phase of the rock art of valcamonica shows connections at a large scale with more contemporary contexts, but nothing in common with the most recent phases. the earliest phase is not in continuity with the holocene phases, it is not a proto-phase. so, the definition of “proto-camunnian” becomes misleading and has to be avoided (sigari, 2022; sigari & fossati, 2021b). 3. the first human groups in the valley 3.1. palaeolithic rock art of the valcamonica despite the high concentration of prehistoric rock art in valcamonica, the number of graphic units attributed to the upper palaeolithic is very limited and concentrated only in two rocks, rock no. 6 and rock no. 34. according to anati (1982), these figures portray only animal figures and number 10: 9 are on rock no. 6 and 1 on rock no. 34.the graphic units can be grouped into two categories: zoomorph (8) and unidentifiable (1). the zoomorphs are deer (2), elk (3), fish (3) and a generic caprid (anati, 1982). a recent review updated the number of graphic units up to 15: 2 deer, 3 elks (6 more elks are actually under-study), 2 fish, 1 caprid and 1 non-figurative motif (sigari, 2022). among the worth mentioning themes, we recognise the elk figures that disappear from the rock art production of the holocene of valcamonica. conversely, more examples of elk representations can be found in the palaeolithic parietal and portable art of italy, respectively in the caviglione cave and tagliente shelter (sigari, 2022), confirming the presence of the animal in the imagery of the human groups that lived in the north of the italian peninsula after the lgm and possibly saw and hunted the animal, as witnessed in the tagliente shelter (fasser et al., 2022). further elk representations can be found in the palaeolithic art of europe as already discussed both in (braun, 2020) and (sigari, 2022). these representations are a valid reference in the study of the palaeoenvironment of the area, since their presence indicates the existence of open humid areas, rich in water, in the vicinity. the 15 petroglyphs of luine were chronologically attributed to the late upper palaeolithic graphic tradition according to their style, theme (especially for the elks, whose presence in the valley was limited to a very short period of time), and to the analysis of the palimpsests, i.e. the overlapping relationships with other motifs (sigari, 2022; sigari & fossati, 2021b). in terms of graphic composition, all the figures, with the exception of the idol-form on luine.034, portray big size animal figures, traced with a main outline marking a disproportioned body and the description of secondary details, e.g. the eye, the nostril and the mouth. they have a strong naturalism and are overlapped by all the other petroglyphs attributed to more recent chrono-cultural horizons (inscriptions, warriors, cup marks, circles…) (sigari, 2022; sigari & fossati, 2021b). 3.2. the oldest human occupation of the valley according to the literature, the human occupation of the valley during the late upper palaeolithic is witnessed only by two sites: the cividate camuno hut (poggiani keller, 1988) and breno castle (fedele, 1988). the discovery of the cividate camuno hut offered an absolute date to what is the most ancient settlement found in camonica valley so far, 13,805±440 bp 14c, 18,067-15,577 cal. bp (poggiani keller, 1988, 2010; sigari & fossati, 2021a). so it can be assumed that the bottom of the valley and the areas sitting at the lowest altitudes, including luine, were freed by the glacier around 16-17 ka bp, offering new territories to be settled (biagi, 2003; ravazzi et al., 2012). the site is located on the left bank of the oglio river, in a sheltered area under the santo stefano cliff at c. 280 m a.s.l. the second site attributed to the epigravettian, according to the lithic assemblage found, is the breno castel site 3 (bc3) with its layer a2 (biagi, 2003; fedele, 1988). however, the few reported data and the absence of dating series to confirm the antiquity of the human occupation of bc3, invite us to prudently not take it into account for the moment. 4. methods preliminary geomorphological analyses were performed through remote sensing mapping to obtain a general flightview of the landscape into which the palaeolithic sites of valcamonica, i.e. cividate camuno hut, rock no. 6 and 34 are. the two rocks are located c. 500 m apart from one another and so are considered two different sites. recent high-resolution satellite imagery was visualised and extrapolated from the quickmapservices plugin (nextgis, 2011) within qgis 3.16 (qgis development team, 2021). digital terrain models-dtm at 5x5 m grid of resolution and the channel network and geological, geomorphological and structural elements were derived from the geoportale of lombardia and from the geological sheet “breno” (regione lombardia, 2020; furlanetto et al., 2018) (fig. 2). elevation-dependent colour scale, hillshade mod for the viewshed analysis (cuckovic, 2016). a viewpoint was fixed after identifying the observer’s location which corresponds to the position of the sites. from here the reference dtm, a radius of 10 km, observer’s height, 1.65 m were set up. afterwards, the visibility analysis was started utilising a binary viewshed that returned two parameters of visibility and non-visibility indicated with the colour red (visible) and white (non-visible). after that els and contour lines at 10 m derived from digital terrain models were elaborated to highlight the distribution of the landforms. in addition, an aspect model map, elaborated on the dtm-digital terrain model, was employed to understand the directions of slope exposures, especially in the proximity of the sites topographic relationships between the sites and their intervisibility were investigated with a qgis plug-in 4 fig. 2 (a) digital terrain model of the study area. (b) schematic geological and geomorphological sketches of the area surrounding cividate camuno. the legend reports the acronyms of the bedrock as in the geological sheet "breno": “bre” breno formation (from here onwards: fm.) (lowermiddle carnic), “esi” esino limestone fm. (upper ladinic-lower carnic), “wen” wengen fm. (upper ladiniclower carnic), “buc” buchenstein fm. (upper anisian-lower ladinic), “prz” prezzo limestone fm. (upper anisian). (c) schematic geological and geomorphological sketches of the area surrounding the luine hill. the legend reports the acronyms of the bedrock as in the geological sheet "breno": “cdg1” pietra simona member of dosso dei galli conglomerate fm. (lower permian), “auc” auccia vulcanite fm.(lower permian), “ver” verrucano lombardo fm (upper permian) and “ser” servino fm. (lower trias) (geological sheet “breno” available at https://www.isprambiente.gov.it/media/carg/78_breno/foglio.html) (map editing: l. forti). sigari d., forti l. fig. 3 tracings of the palaeolithic engraved figures of luine rocks no. 6 (a-d) and 34 (e) (kindly provided by the archaeological cooperative society “le orme dell’uomo”). 5 through the “r.mapcalsimple” tool of qgis, each viewshed of rocks no. 6 and 34, and cividate camuno was interpolated to extract a map into which the common view areas are highlighted. lastly, the pathways between the cividate camuno hut and the luine hill were investigated with the “least cost path analysis” plugin in qgis to find the optimal path between two points in a raster. all the data have been re-projected to wgs 84utm zone 32n reference system. 5. preliminary results 5.1. cividate camuno: geomorphological and archaeological settings cividate camuno is located along the left banks of the oglio river, in an area characterised by an upstream narrowing of the valley, where the river displays meandering plan geometry. this narrowing is associated with the development of an alluvial fan to the nw of the town, formed by the right tributary lanico river that shifts the flow of the oglio river towards se, and by the action of the fault that borders the ridge ne cividate camuno. in the proximity of the town, the valley widens and the plan geometry of the oglio river becomes less meandering and straight. from this point, the river flows through an alluvial plain composed of pebbles and fine sediments. moreover, several colluvial and till deposits were recognised along the slope (forcella et al., 2012) (fig. 2b). in the 80’s, archaeological investigations carried out in 1988, 1992 and 1995, focused on the roman house in via palazzo in cividate camuno. the site is located close to an oglio river bend, in a sheltered area under the santo stefano cliff at c. 280 m a.s.l.. here, different archaeological layers were exposed, confirming the long use of the site since the late upper palaeolithic. indeed, the stratigraphic sequence revealed a level dated to 13,805±440 bp, covered by a mesolithic layer, over which lay, in order, a neolithic (c. 6 ka bp) level, traces of a copper age frequentation (c. 2.5-3 ka bp), evidence of human presence during both bronze and iron age, and finally the roman house, whose foundations compromised the conservation of the bronze and iron age layers (poggiani keller, 2010). the extent of the excavated area is limited but, in correspondence with the so-called vano 1, under a thick sterile sandy level, which was interpreted as the effect of the river flooding (poggiani keller, 2010), a circular living area was brought to light. the size of this surface has a c. 5.6 m diameter and some traces, i.e. pole-holes, led to interpret it as the evidence of a hut. lithic industry, including short scrapers and a bipolar backed point (biagi, 1997), and faunal remains, with the identification of deer, roe deer and ibex (poggiani keller, 2010), were recovered within the area. this material is currently under-review and we are confident that new important novelties will come out. 5.2. luine hill: geomorphological, rock art and archaeological settings the luine hill (45°53'17''n, 10°10'46''e) covers an area of approximately 850 x 600 m that is commonly divided into three parts/localities: crape, simoni and luine. at the confluence of the oglio and dezzo rivers, it reaches an altitude of 365 m a.s.l. (anati, 1962, 1982; laeng, 1956; sigari & fossati, 2021b). the hill is composed of the lower permian sandstone of pietra serena, member of dosso dei galli conglomerate formation (assereto & casati, 1965; lombardi, 2006; furlanetto et al., 2018) (fig. 2c). the geomorphological setting of the area was valcamonica rock art sites-landscape nexus in the upper palaeolithic 6 among the whole record of engraved rocks, two are worth mentioning, rock no. 6 and 34, which have the most ancient petroglyphs of valcamonica (anati, 1974, 1975, 1982; sigari & fossati, 2021a, 2021b). the figures of this ancient period are very few and represent animals, mainly elk, deer, and fish figures, and a geometric motif that show features that tie them to the style and chronology of the upper palaeolithic art of western europe (sigari, 2022; sigari & fossati, 2021a, 2021b) (fig. 3). to deepen the issue of the chronology and the use of the site, during the triennium 1968-1970, anati and his team excavated 26 test pits to explore the possible presence of any archaeological deposit within the area of the hill. they discovered small deposits from the neolithic, bronze and iron ages (anati, 1974, 1982). in the test pit n. 5, in front of rock no. 53, archaeologists brought to light the residuals of a burning area, though no evidence of material culture were found associated with it. nevertheless, anati hypothesised that it would represent the most ancient stratigraphic layer, witnessing the human presence “soon after the retreat of the glacier” since it “probably dates back to the pre-boreal or beginning of boreal, so c. 9,000 years ago” (anati, 1982: 53). 5.3. rock no. 6 rock no. 6 (45°53'19''n, 10°10'58''e) is a large and wide rock outcrop on the north-eastern side of the luine hill. it is located in crape at 290 m a.s.l.. the main enmodelled after the melting of lgm ice masses. the hill is bordered to the east by the valley floor where the oglio river flows in the alluvial plain with a meandering river planform. here, the alluvial plain is composed of gravel and fine sediments. despite the heavy anthropisation, with impactful urbanisation in this part of the alluvial plain, different palaeochannels were recognised in the inner part of the main meander, which is sw to luine hill. differently, southwards, where the dezzo river flows into the oglio river, the wide alluvial fan shifts and influences the river shape of oglio river with the development of a straight reach. finally, west to the luine hill, at the footslope of the walls of the valley, till and slope deposits were recognised with several erosional scarps (fig. 2c). thanks to its 102 engraved rocks, with c. 20,000 petroglyphs, luine hill boasts the third richest concentration of rock art of valcamonica. though all the engraved motifs belong to a long chronology, the majority of them date between the neolithic and bronze age, in contrast with the mid-valley where most of the petroglyphs belong to the iron age. among the main figurative themes of luine we recognise zoomorphic, anthropomorphic, and geometric figures, other symbols including circles, meanders, spirals, zig-zags, labyrinths, and camunnian roses, weapons, shield-forms, and tools, idol-forms, topographics, dwellings and inscriptions. all these graphic units were engraved in the rocks, both pecking and scratching. sometimes both techniques were used to do a figure. fig. 4 panoramic view over rock no. 6 and the valley (photo: d. sigari). sigari d., forti l. 7 graved surface slopes eastwards to the oglio river. on its western side, the inclination of the rock changes to an almost vertical surface exposed to the west. lcr.006 measures 25 x 11 m. rock no. 6 is situated just above an 80 metres high overhang, as such it is impossible to access it from the bottom of the valley. the only accessible way to reach it is from the west, following a relatively easy path along the eastern side of the hill (sigari & fossati, 2021b) (fig. 4). the rock was discovered by g. laeng and e. süss in 1955. three years after their brief report in the commentari dell’ateneo di brescia (laeng, 1956). e. anati and his team started the recording of the rock, counting up to 342 figures (anati, 1962, 1982). however, the scholar never completed the documentation work, admitting that “it was a chore and remained incomplete” (anati, 1982: 7). the main figurative themes of this engraved rock are: animals, topographic, inscriptions and weapons, circles. all of them were pecked and/or scratched. 5.4. rock no. 34 rock no. 34 (45°53'11''n, 10°10'40''e) is a multifaced sandstone outcrop at an altitude of 315 m a.s.l. in the locality of luine. it is one of the largest rocks within the luine hill and has one with the most abundant amount of engravings in valcamonica. the luine.034 is set on the southern slope of the hill, dominating the lower part of the valley and the area of confluence of the dezzo river and oglio river. it can be accessed both from its upper part and from the lower section, according to the visit direction path (sigari & fossati, 2021b) (fig. 5). the rock was fully brought to light in the early seventies, and, at the end of its cleaning, around 1,000 engravings were identified (anati 1974; 1982). among the most impressive graphic units found on this rock, there is a deer figure with the head turned backwards dated to the palaeolithic (sigari, 2022). the recent review undertaken by one of the authors (d.s.) showed that the deer overlaps a big non-figurative motif, witnessing two graphic phases at least (sigari, 2022). these graphic units are in the so-called sector a which corresponds to the most elevated part of the rock outcrop. the sector is westward oriented and is characterised by different figurative themes: animals, weapons, shield-forms, warriors. all of them were pecked and/or scratched. conversely, the panel b that is southward oriented extends over a wider surface than panel a and has more figurative themes, including labyrinth, zigzag, and camunnian rose which were all done from the neolithic onwards. 6. discussion and further perspectives the first maps elaborated within the framework of the parc project, here presented and discussed, consider the evidence of the most ancient human presence in the valcamonica, which seems to be datable soon after the lgm, i.e. around 17,000 years bp (see: sigari, 2022). at that time the valley floor of valcamonica was completely occupied by the water of the paleolake of iseo that reached the area just south of cividate camuno. therefore, the landscape in which the palaeolithic human groups lived at that time was characterised by water and steep walls of the valley. within this scenario, the main topographic features visible from cividate camuno were the ridges that actually rise from the valley floor. one of these was surely the luine hill, which is at the footslope of the valley wall and in the correspondence of the junction of the dezzo and oglio rivers, forming an elevated and protected place. the abundance of water resources after the retreat of the glacier supports the chronological terminus post quem for the engraved elk figures that were probably inspired by the presence of this animal in the area at that time. to further strengthen it, we recall the elk refig. 5 (a) panoramic view from rock no. 34 toward south over the valley to the iseo lake; (b) the deer with the turned head of rock no. 34 (photos: d. sigari). valcamonica rock art sites-landscape nexus in the upper palaeolithic 8 engravings of the luine hill were done in the same period, and aiming to understand any mobility system between the two sites, the cross correlation between palaeoenvironmental reconstruction and preliminary geomorphological analysis suggests that possible linking routes were located on the right footslope side of the valley, that was some metres above the level of the actual alluvial plain. furthermore, with the goal of establishing the existence of any visibility pattern between the rock art and settlement sites, and any intentionality in terms of territory control from them, we used the viewshed analysis to estimate the visibility range from each site over the surrounding territory. the hut location in cividate camuno offers a limited view over the valley and the control area does not cover all of the luine hill area (fig. 6a). differently, from the elevated position of rock no. 6, the viewshed projection highlights a visibility area that reaches the vicinity of the santo stefano cliff, under which the hut was found (fig. 6b). the location of rock no. 34 on the southern slope of the luine hill excludes any territory control to the north. nevertheless, it provides a preferential view over mains from the tagliente shelter dating back to between c. 17-14 ka bp (fasser et al., 2022). to provide a characterisation of the post-lgm palaeolithic landscape surrounding the selected sites, the dtm map clearly enhances the features of the camonica valley, which is an alluvial valley with very steep sides (fig. 2). the dtm served as well as a base-map to understand some key issues, i.e. where the sites are, what the relationship between landscape and rock art is and how the rock art was spatially organised into the valley space if there was any relationship between the symbolic space and the living areas and finally between rock art and visibility. what emerges so far is that the living area is at the bottom of the valley under the santo stefano cliff and close to the river, at a lower altitude, in order to have the best protection and the easiest access to water resources too. differently, the position of the engraved rocks on the hill sides and the edge of an overhang favours a wide view over the surrounding territory, but a scarce, almost unfeasible view over the sites from the bottom of the valley. assuming that the cividate camuno hut and the fig. 6 (a) viewshed elaboration map where the visible and non-visible areas within a 10 km of circle buffer from the cividate camuno hut are reported. (b) viewshed elaboration map where the visible and non-visible areas within a 10 km of circle buffer from the engraved rock no. 6 of luine hill are reported. (c ) viewshed elaboration map where the visible and non-visible areas within a 10 km of circle buffer from the engraved rock no. 34 of luine hill are reported. (d) viewshed elaboration map where the common visible areas from all the three considered sites are reported (map editing: l. forti). sigari d., forti l. 9 fig. 7 (a) view over the valley from rock no. 6 (photo: d. sigari). (b) historical photo taken during the first documentation activities of rock no. 6 (photo kindly provided by the historical archive of the centro camuno di studi preistorici, eur62:lxxx-10). the white arrows point common key-elements of the landscape surrounding rock no. 6, that clearly show how much the landscape has changed and the urbanisation has grown during the last 60 years (editing: d. sigari). valcamonica rock art sites-landscape nexus in the upper palaeolithic the valley till the iseo lake for some kilometres. furthermore, the palaeolithic engravings of luine.034 are on an almost vertical panel, which faces the west. so, hiding the figures from the bottom of the valley and making them visible only to the viewers who get close to it is evident (fig. 6c). the invisibility of the engravings from a distance invites us to consider cultural choices in selecting hidden places from where there is a good view over the surrounding territory, but that requires a displacement to the site. so, the concept of private and public art in the valcamonica rock art, which has recently been sketched in a paper about the holocene parietal evidence (fossati, 2016), seems to be finally relevant in approaching the palaeolithic rock art too. more comparative cultural suggestions that may confirm the intentional selection of specific hidden sites can be found in the ethnography, where scholars report how some populations chose isolated places with a panoramic view of the surrounding landscape (e.g.: loubser, 2010; sundstrom, 2006). to check and establish any intervisibility pattern among the selected sites and to understand the use of the landscape and the relationships among the rock art and settlement sites, we crossrelated the viewshed projections from luine.034, lcr.006 and cividate camuno hut highlighting how the commonly visible areas are almost absent and limited to a few steep points on the right hydrographic bank and on escarpment edges of the altissimo mountain (fig. 6d). therefore, the almost total absence of common intervisibility points reinforces the idea of driven cultural choices in selecting isolated and hidden sites to produce parietal engravings during the palaeolithic. the luine rock art of the pleistocene responds to limited access and visibility rules. in other words, it was not public art but required knowledge of the place, and the maker/viewer was obliged to go on the site to finally access the panel. undoubtedly, the issue of visibility is strictly linked to the changing landscapes. difficulties in advancing hypotheses based on the modern landscape of valcamonica are clearly evident already by the use of historical photos, which show how much the anthropic impact transformed the valley aspect during the last 80 years (fig. 7). therefore, it is easy to imagine how much the valcamonica landscape has changed over the last 17 10 fig. 8 (a) digital terrain model of the lower sector of valcamonica where the palaeolithic paleoshore of the iseo lake based on the reconstruction by pini et al., (2016) is reported in light blue. the dark blue colour indicates the actual shore of the lake. (b) least cost path analysis applied to the study area between cividate camuno and luine hill. (c) interpolation of the ancient shore line of the iseo lake and the least cost path analysis. with the white dash line we hypothesised a possible road that connects cividate camuno and the luine hill rock art site (map editing: l. forti). sigari d., forti l. millennia, both for climatic and environmental reasons and for anthropic actions. however, despite the almost lack of data for prehistoric times, we can reasonably consider how dynamic environmental conditions may have favoured the selection of the rocks, the accessibility to the sites and the visibility among them. so, according to the previous literature, we can suggest that the amelioration of the climatic conditions and the subsequent environmental changes led to differently characterise the visibility patterns within the valley space. if after the lgm an open environment characterised the valley, possibly exposing the sandstone outcrops and/or facilitating the intervisibility between the sites, later the expansion of the timberline at lower altitudes reduced any visibility pattern. so, the valcamonica territory was possibly conceived as a structured space with living areas which were easily accessible going upriver, and ritual places which were hidden and required the knowledge of the valley to access the rock art. finally, crossrelating the dtm elaboration with the paleoenvironment reconstruction based on what was reported in pini et al. (2016) (fig. 8a), and the least cost path analysis that highlights the fastest and easiest path connecting cividate camuno and luine hill (fig. 8b), we suggest that the possible path, between the cividate camuno hut and the luine hill followed by the first settlers of the valley, run along the western foothills of the valley beside the paleolake shore (fig. 8c). surely, we are aware that we could take into account only very little data. however, we keep an open mind to further integrate any novelty that may implement our knowledge about the first settlers of the valcamonica. moreover, we consider the implementation of the record as a useful tool to evaluate more parameters such as the terrain orientation to analyse the taphonomic impact on the rock art preservation according to the vegetation growth, humidity, weathering and anthropic impact. indeed, the elaboration of the topographic parameters through the application of the automated plugin qgis at a higher resolution with a bigger number of data will certainly provide more interesting information. to do that, the parc project that we are undertaking considers approaching more recent chronologies of the valcamonica rock art too. the next focus will be the paspardo territory in the mid-valley, where there is a higher concentration of engraved rocks with images belonging to different phases. this approach will consider a multi-scale analysis that will permit to access the relationship with the environmental resources, the landscape features and the cultural choices along the different rock art chronologies of the valley. therefore, we are confident that the newly started parc project will finally provide new insight into the dynamic aspects of the rock art both in valcamonica and other open-air contexts, tracing new research avenues for the archaeology of valcamonica and the rock art research. acknowledgements “parc-paesaggi dell’arte rupestre camuna” project is funded by the centro camuno di studi preistorici. the recording and analysis of the palaeolithic engravings of luine hill is part of the “cervidi della valcamonica (cer.val.): tra incisioni rupestri, tradizioni popolari e cambiamenti climatici” project funded by the caicomitato centrale gruppo terre alte. we are thankful to maria grazia gobossi e mario marini whose work in preserving and promoting the luine archaeological park is fundamental and precious, and they keep on with this important work with sincere curiosity and great enthusiasm. we are grateful to francesca roncoroni for supervising the development of the parc project, angelo eugenio fossati for facilitating the access to the tracings of the archaeological cooperative society “le orme dell’uomo”. last, but not least, we thank sujitha pillai for assisting with the written english review. references anati e. 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(eds.), the archaeology of rock-art. cambridge university press, cambridge, 285-301. 14 sigari d., forti l. ms. received: june 1, 2022 revised: october 14, 2022 accepted: november 14, 2022 avaiable online: december 5, 2022 imp.kalicki& river response to the holocene climatic fluctuations: a case study from zelvianka river valley (belorussia) tomasz kalicki1, gilberto calderoni2 & valentina p. zernitskaya3 1department of geomorphology and hydrology, institute of geography and spatial organization, polish academy of sciences, krakow, poland ph.: +48 124293856 2dipartimento di scienze della terra, università “la sapienza”, p.le a. moro, 5 00185 istituto di geologia ambientale e geoingegneria (cnr) roma, italia. e-mail: gilberto.calderoni@uniroma1.it 3institute of geological sciences, national academy of sciences, kuprevicha str., 7 220141 minsk, belorussia. abstract: kalicki t. (et.al.), river response to the holocene climatic fluctuations: a case study from zelvianka river valley (belorussia). (it issn 0394-3356, 2004). a multidisciplinary research aimed at depicting the evolution of zelvianka river valley (nw belorussia) during the holocene has been carried out. the valley incision started at the local ice-sheet terminus in the young pleniglacial following the pomerian stage of the last glaciation (some 16÷15 ka bp) and, as marked by important changes of the river regime, was virtually over at c. 13.8 ka bp (middle lithuanian stage of deglaciation). detailed geomorphologic survey coupled with stratigraphic analysis, 14c dating and pollen spectra provided sound evidence that the complex structure of the valley bottom resulted from the lateral migration of the river which in turn depended upon large-scale climatic changes. besides of critically reviewing the literature data new, 14c dated pollen chronostratigraphies, fairly consistent with the up to date regional palynologic framework were obtained. actually it has been found that the most important channel and sedimentation changes cluster at the al/yd transition, c. 9300 bp, bo/at transition, middle atlantic, c. 4200 bp, c. 3250-3000 bp, roman time (2100 bp) and 1000-900 bp, thus matching the timing of humid and cool climatic phases recorded by the enhanced activity of belorussian and central european rivers. though the first prehistoric settlements over the study area date back to late neolithic, zelvianka valley was virtually unaffected by the human impact, except from some low intensity, local aeolian processes which developed in the subboreal and subatlantic on the deforested spots riassunto: kalicki t. (et.al.), effetti delle fluttuazioni climatiche oloceniche sull’evoluzione della valle del fiume zelvianka (n-w bielorussia). (it issn 0394-3356, 2004). e’ stata effettuata una ricerca multidisciplinare finalizzata alla ricostruzione dei tratti evolutivi più salienti della valle del fiume zalvianka (bielorussia nord occidentale) durante l’olocene. l’incisione di questa valle, iniziatasi nel pleniglaciale al termine dello stadio pomeriano dell’ultima glaciazione (ca. 16÷15 ka bp) e conclusasi a ca. 13,8 ka bp (media deglaciazione lituana), ha registrato importanti cambiamenti del regime fluviale. i dati geomorfologici, stratigrafici, palinologici unitamente a quelli della cronologia radiocarbonio concordano nell’indicare che la complessa struttura del fondo della valle deriva dalle migrazioni laterali del fiume che, a loro volta riflettono variaizioni climatiche di portata almeno regionale. lo studio ha evidenziato che le maggiori variazioni tanto nel regime di sedimentazione che nella direzione del corso fluviale si sono verificate alla transizione alleröd/dryas iii, a ca, 9300 bp, alla transizione boreale/atlantico inferiore, nel medio atlantico, a ca. 4200 bp, a ca. 3250÷3000 bp, in epoca romana (2100 bp) ed infine dal 1000 al 900 bp. la datazione di tali eventi ne rivela la contemporaneità con fasi climatiche umide e fredde di portata almeno regionale in quanto precedentemente riportate per molte valli fluviali della bielorussia e dell’europa centrale. nonostante la presenza di insediamenti umani nell’area di studio a partire dall’ultimo neolitico, la valle del fiume zelvianka non mostra significative evidenze di impatto antropico, eccezion fatta per modesti processi eolici attivi nel pre-boreale e nell’atlantico inferiore nelle modeste aree soggette a deforestazione da parte dell’uomo. keywords: holocene, belorussia, climate fluctuations, river valley, radiocarbon dating, pollen analysis. parole chiave: bielorussia, olocene, fluttuazioni climatiche, cronologia radiocarbonio, analisi pollinica. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 165-180 introduction the pleistocene development of zelvianka valley (fig.1) resulted from the degradation of neman stream sozhian (moscovian) ice sheet, damming of neman river by valday ice sheet and level changes of the late valday (vistulian) ice-dam skidel lake (vozniachuk and valchik, 1978). zelvianka valley cuts the belorussian upland accordingly to the glacial valley of the kataglacial period of sozhian glaciation (gorecki, 1980). the valley, only 100-200 m wide at a narrow gap section nearby piaski village (piaski gate), where it crosses the northernmost morainic ridge with glaciotectonic features (levkov, 1980), broadens suddenly up to 2.5-3.0 km in the downstream flat upper neman plain (fedenya et al., 1985). the valley evolution during the last glaciation was controlled by the recurrent fluctuations of the ice sheet terminus. following river damming by the ice sheet, fine sands with silt intercalations (usviacha series) accumulated in neman as well as in zelvianka river valleys. then, the whole upper neman plain was overflooded (maximum level: 128-138 m a.s.l.) by the ice-dam skidel lake (vozniachuk and valchik, 1978) and a limnoglacial suite, resembling varve sediments (thin fine sands and sandy silts layers) was deposited (kovbasyuk and ivanov, 1998). the sequence, with ice wedges at the top (levkov et al., 1988), records the progressive shallowing of skidel lake during the recession of the last ice sheet, when terraces were originated 166 t. kalicki, g. calderoni & v. zernitskaya fig. 1 sketch map of the study area. the location of the reference pollen spectra mentioned in the text is as follows:1 – podbarany, 2 – ogorodniki, 3 – kremushovka, 4 morino. by the zelvianka river erosion of the limnological suite. the incision, 4-5 m deep near piaski, deepens gradually downstream up to 10-11 m at the river mouth. at present the lacustrine sediments blanket a very flat plain (116-117 m a.s.l.) and only small relics of the former terraces, barren of organic matter are preserved. despite the numerous companion papers focusing on the zelvianka river valley near piaski village (fedenya et al., 1985, 1992; levkov et al., 1988; ivanov, 1993, 2001; ivanov and yelovicheva, 1997), the overall framework for the lateglacial-holocene development of the valley is still unsatisfactory for relying on palaeobotanical and palaeozoological chronosequences lacking isotope dating and accurate location. this work attempts a detailed reconstruction of the lateglacial-holocene evolution of zelvianka river valley near piaski by considering new data and, following a critical evaluation of the literature. the new established pollen chronostratigraphies are, for the first time in the area, also supported by 14c readings. our results are of regional scale concern, as valleys developed at the ice sheet termini on limnoglacial sediments accumulated in ice-dammed lakes are common features in northern russian (kvasov, 1976, 1987) and masovian plains. methods a preliminary literature survey strongly suggested that further field work was needed for locating, checking stratigraphy and possibly re-sampling the reported profiles as well as selecting and sampling new key outcrops. samples for palynological analyses, collected at 5-8 cm intervals, were submitted to the standard chemical pretreatment (erdtman, 1936; pokrovskaya, 1950). the ap (arboreal pollen) + nap (non-arboreal pollen) sum, shrub species included, were considered. the percentages of other microfossils (pollen of aquatic taxa and spores) were calculated from ap+nap pollen sum. tilia and tilia-graph programs (grimm, 1992) were used for calculation and plotting, respectively. the chronozonal distinction, matching the criteria after mangerud et al. (1974), relied on both 14c dating and correlation with the 14c dated ap spectra from the sites of ogorodniki, morino, kremushovka and podbarany (vozniachuk and valchik, 1978; kalicki et al., 2000) located along the neman river valley near piaski site (fig. 1). radiocarbon dating was run with the liquid scintillation counting (lsc) technique on selected fractions of the organic matter in the sediment samples following decarbonation and removal of the mobile organics (calderoni and turi, 1998). details on the chemical and counting protocols, equipments, 14c decay rate measurement and age calculation were given elsewhere (calderoni and petrone, 1992). present-day environment the c. 170 km long zelvianka river begins between lidziany and kulyavichy villages and drains a 1940 km2 catchment with a 0.41 km/km2 river network density. river slope and annual discharge at the mouth average 0.41‰ and 11 m3/s, respectively. the natural 167river response to the holocene ... high sinuosity meandering channel, 15-20 m wide, is confined between steep, sandy banks. upstream of the study area two river sections (44.2 km long) have been channeled to supply water to the zelva and papiernia reservoirs. the valley broadens from 0.5 to 3-4 km in the lower reach and the flat flood plain, only recently reclaimed, is up to 2.5 km wide except for the middle and lower reaches, where it narrows to 0.4-0.6 km (blakitnaya kniga belorusi, 1994). the study area is 14 km upstream of the zelvianka river mouth to the neman river. at piaski gauge station the drainage basin accounts for 1800 km2 (mean altitude: 166 m a.s.l.), most being currently cultivated, 17% forested and 14% consisting of marshes, swamps and peat bogs. major forests, with pine communities (pinetum callunosum, pinetum vacciniosum) far predominant over fir, hornbeam and oak, spread along the right bank of zelvianka river to the north of piaski village. alnus glutinosa, betula pubescens, corylus avellana, salix lopponum and salix aurita grow in the lowermost swampy areas with peaty soil. dryopteris thelypteris, thelypteris palustris, filipendula ulmaria, comarum palustre, galium palustre and carex are the dominant herbs. fig. 2 shows the mean monthly, maximum and minimum discharge of zelvianka river since 1955 through 1975: the meltwater peak discharge in april points out the nival regime of the river. the mean annual discharge ranged from 18.9 to 6.59 m3/s (mean: 9.42 m3/s) and peaked at 289 m3/s in april 17, 1958. the water level during the spring floods is up to more than 2 m higher (mean: 676 cm) than the mean water stage (mean: 469 cm). the zelvianka river is yearly frozen during some 75 days, as an average from december 25 up to march 11-23 (gosudarstviennyy vodnyy kadastv, 1978). valley bottom structure along the 3 km long bifurcated reach of zelvianka river beginning 2 km upstream of piaski village the valley consists of two subparallel branches separated by an erosional remnant of the limnoglacial deposits on which the village lies at 116 m a.s.l. (fig. 3). the southern branch, narrower and straighter than the northern one, shows, in the left bank of the ending part, one confined paleomeander cutting the limnoglacial series. most of the studies were addressed to the northern valley branch for its well developed, up to 1 km wide flood plains. here fedenya et al. (1992) and kovbasyuk and ivanov (1998) recognized two and three steps, respectively, at 3.5 (4.0)-4.5, 2.0-3.0 and 1.0-1.5 m above river level (a.r.l.). upper flood plain remnants of this level, less than 200 m wide, are recorded on both valley sides by a fining-upward alluvia sequence (fedenya et al., 1992). the new field data, however, pointed out that the step height is morphology-dependent, thus implying that, for instance at piaski-2, the paleochannels are significantly lower (2.53.0 m a.r.l) relative to the point bars (4.5-5.0 m a.r.l.). further, the lag deposits were actually found at c. 1 m 168 a.r.l., not below the river water level as previously reported by kovbasyuk and ivanov (1998).only one among the profiles herein shown originated from the southern branch of the valley. southern valley branch piaski-mill this section (profile 11 after fedenya et al., 1985, 1992) is near the scarp of the valley, where the river cuts the piaski glaciodislocation and thus alluvia, only 3.6 m thick, overlies the chalk (fig. 3 and 4). mammal, amphibia and fish bones were found in the sands at 3.25 m deep. because the mammalian assemblage mirrors mixed and deciduous forests, meadow and aquatic biotopes and the frog bones steppe environment, it has been inferred that the sediment deposited at the southern limit of the forest zone. upward (2-3 m deep), a humified sandy layer contains entomofauna, similar to that of present times, that for including taxa of fast flowing water and stagnant or slowly flowing water (like in oxbow lakes with clay bottom) pinpoints the biotope varieties in the river valley. the occurrence of melolontha sp. suggested that sediments accumulated in the late atlantic, thus under warmer and drier climate than at present. based on the paleozoological data the alluvia was referred to the middle holocene. northern valley branch piaski-2 this new profile, c. 3 m a.r.l. and very close to the right scarp of the valley bottom, shows at the base a paleochannel fill overlain by sandy-silty overbank deposits (fig. 3 and 4). the former feature is made up by two units, the lower one (3.00-2.65 m deep), referred to the beginning of the infilling, consists of clastic sediments (clayey sands with gravels up to 0.5 cm), scattered organic matter and vegetal debris. the overlying organic sediments unit (2.65-1.10 m deep) displays, bottom to top, gyttja and peat. just upward a yellow-gray-green colored, rich in vegetal debris gyttja level is shown. the occurrence of thin layers and lenses of coarse sands and small gravels (up to 0.5 cm) in its lower part points to intermittent river/oxbow lake communication. the pollen spectrum for piaski-2 (fig. 5) shows that the gyttja bottom (2.65-2.45 m deep), dated at 10,670±100 yr bp (rome-1339), belongs to lpaz betula nana–pinus– nap. the high nap (17.5-25.5%), together with betula nana type, alnaster (alnus viridis), juniperus and scant selaginella selaginoides, reflects cold climate and openforest landscape. lemna and polygonum amphibium grew in the oxbow lake and phragmites, epilobium palustris and equisetum in the marshes. in the upward 30 cm of gyttja (2.45-2.15 m deep) lpaz changes into betula–pinus–salix-nap. here betula, pinus and salix increase and nap, attaining 28.5%, is dominated by artemisia. both polygonum amphibium and myriophyllum peaks reflect the ongoing overgrowing of the shallow (less than 3-4 m deep) lake. pollen data are consistent with a yd cooler and drier at the late stage (10,500-10,200 yr bp) than at its beginning. the lowermost 15 cm of the overlying gyttja silts (2.15-2.00 m deep), lpaz pinus, displays pinus predominance, ulmus first appearance and nap decline to a mere 5%. the disappearance of hydrophilous plants, paralleled by a rise of polypodiaceae, dryopteris thelypteris and thelypteris, marks the transition from shallow lake to peat bog. at first glance the comparison between the pollen spectra from piaski-2 and morino in the neman valley (vozniachuk and valchik, 1978) reveals an almost synchronous blooming of pine. in particular, at morino pine predominated prior to 9920±90 fig. 2 monthly maximum, average and minimum discharge of zelvianka river at piaski gauge station during the period 1955-1975 (by t. kalicki) t. kalicki, g. calderoni & v. zernitskaya 169 fig. 3 zelvianka river valley near piaski with study profile and geological section a-b (see fig. 8) (by t. kalicki) river response to the holocene ... 170 fig. 4 study profiles in the zelvianka river valley (by t. kalicki) 1 – chalk, 2 – gravel with sand, 3 – sandy gravel with clay, 4 – sand, 5 – eolian sand, 6 – organic sand, 7 – intercalation of sand and sandy silt,, 8 – sandy silt, 9 – intercalation of peat and sand, 10 – sandy peat, 11 – peaty silt, 12 – peat, 13 – intercalation of gyttja silt and sand, 14 – gyttja silt, 15 – gyttja, 16 – buried soil, 17 – soil, 18 – clayey ball, 19 – peaty ball, 20 – subfossil tree, 21 – detritus, 22 – bones, 23 – shells, 24 – remnant of insects, 25 – older pollen datings (references) reinterpreted by v. p. zernitskaya t. kalicki, g. calderoni & v. zernitskaya 171 f ig . 5 p o lle n d ia g ra m o f th e p ia sk i 2 p ro fil e ( b y v . z e rn it sk a ya ) 1 – g yt tj a , 2 – g yt tj a s ilt , 3 – p e a ty s ilt , 4 – p e a t, 5 – s a n d , 6 – s a n d w it h g ra ve l river response to the holocene ... and 9970±110 yr bp (mig-27 and tln-136, respectively), thus in agreement with the pb-1 (~10,200 – 9800 yr bp) established in zelvianka river valley. the topmost gyttja silts (2.00-1.84 m deep), lpaz betula-pinus-(ulmus), show increase of betula up to 55.3%, further rise of polypodiaceae, thelypteris and stable ulmus. these sediments were assigned to the pb-2 (9800-~9200 yr bp) by analogy with the reference pollen spectra from kremushovka and morino sites (vozniachuk and valchik, 1978), both recording the birch peak between 9920±90 and 9320±100 yr bp (mig-27 and mig-41, respectively). the lower part (1.84-1.70 m deep) of an overlying horizontal-bedded, compact peat layer, lpaz pinusbetula-(corylus), features betula drop, pinus and ulmus rise and appearance of corylus, quercus and alnus along with polypodiaceae predominance among the nap. this implies that the oxbow lake changed into a fern-covered swamp. the timing of a comparable ap spectrum (morino site, vozniachuk and valchik, 1978) spans from 8940±80 to 8590±90 yr bp (mig-28 and mig-29, respectively) and therefore the lpaz has been referred to __ (~9200-8000 yr bp). the upward (1.701.45 m deep) peat, lpaz ulmus-corylus-alnus, exhibits the peaks of ulmus (9.1%), corylus (18.6%) and alnus (20.%), expansion of quercus and tilia and subordinate fraxinus occurrence. the pollen spectrum, typical for at, fairly matches that for podbarany site (zernitskaya, 1999; kalicki et al., 2000). in the middle of the atlantic (1.60-1.55 m deep) the most humid climatic phase is marked by the hydrophiles lemna, thypha latifolia, nuphar lutea, numphaeae and myriophyllum as well as the hygrophiles menta longifolia and menyanthes trifoliata. the organic paleochannel fill ends with severely decomposed clayey peat (1.45-1.10 m deep). the abundant corroded pollen content and the frequent fluctuation of many taxa points to floods and unsteady humidity in the peat bog, now populated by ferns and subjected to pedogenesis. pollen data, though revealing a drop of ulmus and corylus and a rise of pinus, picea, quercus and tilia, were too meagre for any sound chronological assignment. however, the 14c reading (rome1341: 2085±60 yr bp) at the top of these sediments provides an ante quem terminus for their deposition. the bottom of the overbank deposits (1.10 m upward) capping the paleochannel fill displays, bottom to top, two sandy, 2 cm-thick layers overlain by a 12 cm-thick silty-sands layer, that is a suite likely mirroring an abrupt sedimentation change due to a flooding event. pedogenesis overshadowed the primitive structure of the topmost 80 cm of the upward intercalations of horizontally bedded sands and humified silty-sands. data suggest that the paleochannel was cut off at the alleröd/younger dryas transition and then, following fast gyttja accumulation during the younger dryas, the oxbow lake disappeared at the onset of the holocene. the organic paleomeander fill records the humid middle atlantic climatic phase. probably, at the subboreal/subatlantic transition the lowering of the ground water table triggered the weathering of the topmost peat. lastly, in response to the important sedimentation changes caused by floodings in roman times, the peat bog was buried by overbank deposits. piaski-10 this new exposure (fig. 3) shows the sandy level at c. 5 m a.r.l. and the paleochannels piaski-10 and -9 on the upper and middle flood plains, respectively (fig. 6). the former meander cut the higher sandy level and in turn was cut by the latter one. the height of the upper flood plain, less than 3 m in the paleomeander, rises to 4.5-5.0 m a.r.l. at the point bar. the bottom of the paleochannel fill is c. 1.5 m a.r.l. and channel medium sands occur at the base of the profile (fig. 6). the organic silty 172 fig. 6 section across the piaski 9-10 sites (by t. kalicki) and piaski 5 (levkov et al. 1988, modified by t. kalicki) 1 – limnoglacial sediments (intercalations of sand and silt), 2 gravel with sand, 3 – sand, 4 –eolian sand, 5– organic sand, 6 – organic silty sand, 7 – intercalation of sand and organic sandy silt,, 8 – sandy silt, 9 – organic sandy silt, 10 intercalation of peat and sand, 11 – sandy peat, 12 – peat, 13 – gyttja, 14 – lacustrine chalk, 15 – buried soil, 16 – soil, 17 – slump, 18 – iron concretion, 19 – subfossil tree, 20 – detritus, 21 – charcoal, 22 – bones, 23 – shells, 24 – flint artifact, 25 – samples for palaeobotanical macroremnant study, 26 – palaeobotanical dating, 27 – radiocarbon dating; al – alleröd, yd – younger dryas, pb – preboreal, at – atlantic, sb – subboreal t. kalicki, g. calderoni & v. zernitskaya sands (meadow ore) at the bottom of paleomeander fill were dated at 9270±90 yr bp (rome-1337). upward, following a level of lacustrine chalk with bithynia tentaculata pointing to an ephemeral oxbow lake, meadow ore accumulated again. the topmost 0.5 m of the profile consists of overbank silty sands. the early holocene abandoned channel was close enough to the zelvianka river to prevent any subsequent organic accumulation in the paleomeander. piaski-5 this exposure (fig. 3) has been reported (levkov et al., 1988) as a thermokarstic depression infilled by two age-distinct series of alluvia capped by aeolian sands (fig. 6). subfossil pine trees, up to 3 m long, were found in the cross bedding sands and gravels at the bottom of the fill (fig. 6, profile 1). based on the vegetal macroremnants both channel deposits and overlying sandy overbank sediments were dated to the late glacial/preboreal transition. in turn, the depression fill (fig. 6, profile 2) made up by gravel with sands and peats was subsequent, as pointed out by preboreal/ boreal mammal bones (ivanov, 2001) at the bottom of the lag deposits and vegetal macro-debris of the middle and late atlantic mixed forest in the overlying sediments (levkov et al., 1988). both alluvial members are topped by aeolian sands that, for containing at least three paleosols, did deposit intermittently. the sands contain flint tools, likely used for quarrying the chert in the glaciodislocated basement close to piaski some 3400-3200 yr bp (gurina, 1976). however, the previously claimed thermokarstic origin of the depression has to be rejected for two sound reasons. first, the limnoglacial deposits could not accumulate during the maximum expansion of the valday ice sheet (thus, while zelvianka river was frozen) and further, a re-examination of the outcrop revealed two age-distinct paleomeanders cut in the limnoglacial series (fig. 6). thus, the channel deposit underlying the paleomeander fill consists of two diachronous alluvial bodies instead of only the one previously claimed. in addition the top of the late glacial channel facies is 2 m a.r.l. and the older paleomeander cut the limnoglacial series. thus, the slumps on the scarp of the river valley do actually record bank erosion, in analogy with that reported from vistula valley (wasylikowa et al., 1985), rather than thermokarstic processes. the pine trees fallen during the late glacial lateral migration of zelvianka river accumulated in the sandy-gravels deposits. the older paleochannel cut off at the late glacial/holocene transition and in the preboreal was quickly infilled by sandy sediments containing a rather homogeneous assemblage of vegetal macroremnants (fig. 6, profile 1). during the early holocene the younger meander undercut and partly destroyed the fill of the older, abandoned channel, then it was cut off in the middle atlantic. in the late atlantic, following its fast infilling by sands (fig. 6, profile 2), the younger oxbow lake changed into a peat bog. during the subboreal and subatlantic both paleomeanders were covered with aeolian sands in a few phases. the flint artifacts in the buried soils could suggest that human impact played some role in the recurrent aeolian activity. piaski-4 the profile (ivanov and yelovicheva, 1997; ivanov, 2001) is located on a narrow, 10 to 50 m wide, remnant of the upper flood plain, 3.5-4.5 m a.r.l. (fig. 3). basal channel sands with gravels contained well preserved, likely in situ, bones of amphibia, fish and mammals (typical of taiga coenoses) with some tundra species probably of the preboreal/boreal transition (fig. 4). the upward sandy paleochannel fill (3.6-2.9 m deep) is overlain by sandy overbank deposits 1.8 m thick. pollen data point to a continuous sedimentation from the second half of the preboreal through the first half of the subboreal. an overlying silty-sandy buried soil (1.1-0.6 m deep) was assigned to the second half of the subboreal and the aeolian fine sands capping the sequence to the subatlantic by the pollen data. in our opinion, however, the above conclusions are puzzling. actually, the claimed continuous sedimentation from the preboreal through the present is ruled out by paleosol occurrences. further, it is also well known that alluvia is deposited by meandering rivers mostly according to an horizontal rather then a vertical pattern. in addition, no firm conclusions can be drawn from the reported pollen spectrum that for having been determined on sands (also including a paleosol) and for lacking the pollen/corroded pollen ratio, prevents any hiatus recognition. by comparing the piaski-2 and -4 palynostratigraphies it results that the latter lacks the lpaz’s betula-pinus-(ulmus), pinus-betula-(corylus) and ulmus-corylus-alnus, despite all of them all of them are quite evident since pb-2 to the end of at in the piaski-2 pollen spectrum. the lpaz’s pinusquercus, betula-quercus with tilia, carpinus and fagus displayed in the piaski-4 pollen spectrum are typical for the subboreal in belorussia (zernickaja, 1998, zernitskaya, 1999), eastern poland (ralskajasiewiczowa and latalowa, 1996) and southerneast lithuania (kabailiene, 2002). both literature and new data (e.g., piaski-1 profile) constrain the deposition of the piaski-4 sediment suite (fig. 4) within the sb (4.11.7 m deep) and sa (1.7 m-upward). piaski-3 this profile (ivanov, 1993), c. 3.0 m a.r.l. shows basal loams overlain by sandy alluvia (fig. 3, 4). the lower portion (2.5-2.8 m deep) of subhorizontal bedding sandy-gravel channel alluvia contains well preserved, likely in situ, mammal bones pointing to widespread humid mixed forest. palaeozoological and palynological data were judged consistent with a continuous sedimentation during the last 8000 yrs (from at-1 to sa-3). however, the previous criticisms for piaski-4 also apply here, as the reported pollen spectrum, besides depicting only the ap trend, does not show the pollen amounts. akin to piaski-4, as the pollen diagram lacks the at (ulmus-corylus-alnus) while showing both sb and sa chronozones, it is reasonable that piaski-3 sequence deposited since the subboreal. this is also supported by new malacological data (predominance of channel species over those of different biotopes) from the 0.75-3.1 m deep sandy deposits, consistent with alluvia accumulation from the atlantic to the subatlantic (a. f. sanko, pers. comm., 2002). 173river response to the holocene ... 174 f ig . 7 p o lle n d ia g ra m o f th e p ia sk i 1 p ro fil e ( b y v . z e rn it sk a ya ) 1 – g yt tj a s ilt , 2 – p e a t, 3 – s a n d y p e a t, 4 – s a n d y si lt , 5 – s a n d , 6 – s a n d w it h g ra ve l t. kalicki, g. calderoni & v. zernitskaya middle flood plain according to kovbasyuk and ivanov (1998) the middle flood plain is built of sandy overbank deposits rich in vegetal remnants and detritus and devoid of subfossil tree trunks. the overbank/channel sediments boundary lies below the mean river water level. oxbow lakes were filled with humic sands 0.5-1.5 m thick and, sometimes, with peat intercalations up to 1.5-1.8 m thick. contrasting with the previously stated absence of slope and aeolian deposits, new field work at piaski-1 identified thick aeolian sands covers. all the studied profiles herein reported are from the northern branch of the valley. piaski-1 this exposure (fig. 4, profile 5) was referred to the upper flood plain for lying above the river level (fedenya et al., 1985, 1992). by contrast, the new survey established that the topmost 2 m of the sequence are aeolian sands and thus the shown features do belong to the middle flood plain (fig. 3 and 4). at the base of the channel deposits (4.22-4.67 m deep) an assemblage of likely in situ bones of mammals (mostly of mixed and deciduous forests, 25 and 17% of lake banks and meadows, respectively), amphibia of mixed and deciduous forests of middle holocene age and fish were found. the entomological assemblage from the organic paleochannel fill includes species of fast flowing waters together with those of stagnant or slowly flowing waters (as in oxbow lakes with clay bottom) and mirrors the variety of biotopes in the river valley during the middle holocene. at piaski-1 a new, 14c dated pollen diagram has been determined as that previously available placed at the atlantic-early subboreal the peat in the paleochannel, thus in open contrast with the up to date regional palynologic framework (zernitskaya et al., 2003), the sampled exposure shows, bottom to top, four main members including channel deposits, organic paleochannel fill, sandy-silty overbank deposits and aeolian sands (fig. 3 and 4). the basal member, c. 0.5 m thick, consists of medium and coarse sands and correlates with the layer with fossil bones after fedenia et al. (1992). the transition to the overlying paleochannel fill is marked by a lamina of lag deposits (gravels 0.2-0.3 cm in diameter) covered with a 0.5 cm-thick lamina of peaty silts and a 15 cm-thick layer of medium and coarse sands. the upward organic paleochannel fill, submitted to pollen and 14c analyses, shows a 0.5 m-thick gyttja silts (lpaz pinus-quercus at 3.95-3.85 m deep), overlain by 0.7 m-thick peats (fig. 7). the lowermost 5 cm of the gyttja silts, sandy and densely laminated, suggest some river input into the oxbow lake. the lack of sandy intercalations through the upward c. 10 cm points to low sedimentation energy and rules out flood events. the ap pinus and quercus predominate over picea, tilia and carpinus. nuphar, sparganium and typha latifolia grew in the oxbow lake and polypodiaceae, sphagnum in the marshes. the bottom of this early subboreal (sb-1) pollen chronozone was dated at 4105±60 yr bp (rome-1338). it is noted that a comparable pollen spectrum was reported from podbarany site (kalicki et al., 2000) for sediments younger than 4645±50 yr bp (igsb-709). the lacustrine episode of the paleochannel with gyttja silts accumulation lasted up to the end of the subboreal (lpaz betula-quercus-carpinus, 3.85-3.35 m deep). a few sandy laminae in the middle of the gyttja silts record episodic oxbow lake/river contacts. pinus drop parallels the rise of betula, alnus, tilia (6.6%), quercus (20%) and carpinus (2.6%) whereas fagus is far subordinate. the rare hydrophyte typha latifolia indicates a water depth less than 0.5 m. a comparison with the ogorodniki pollen diagram, showing that tilia, quercus and carpinus maximize between 3820±100 and 3530±100 yr bp (tln-163 and mig-44, respectively) and decline between 3530±100 and 2720±90 yr bp (mig-44 and mig-43, respectively), dates these sediments to the sb-2 and sb-3 (~4000-2700 bp). at c. 3000 bp the oxbow lake changed into a marsh where the intermittent grow of trees is recorded by subfossil trunks in the peats. the peat layer includes two sandy peat intercalations. the lower one spans through the uppermost part of lpaz betula-quercus-carpinus, characterized by decrease of pinus, expansion of pioneer vegetation (betula and alnus in deforested areas) and viburnum, sambucus and calluna occurrence. nap in sb-3 sediments (3.50-3.35 m deep) reaches 10% and includes scleranthus, helianthemum and brassicaceae. the rise of xerophytes and heliophytes, e.g., artemisia, chenopodiaceae, cichoriaceae, umbelliferea and asteraceae is matched by poaceae, fagopyrum and urtica dioica appearance. despite the lack of cultural species, the apparent deforestation could be accounted for, at least to some extent, by human impact, in that archaeologic sites of the neman and trzciniec cultures (late neolithic and bronze age, respectively) are known nearby piaski village (charnyavski, 1979; arkhialogiya belarusi, 1997). it is reasonable that following the local pine forests clearance for wood exploitation and flint quarrying in the glaciodislocated chalk, the wind blown sands originated from the deforested areas mixed up with the peat growing in the paleomeander. the concomitant humid climate, recorded by rise of polypodiaceae and picea (up to 5%) and abies occurrence, resulted in trees fallen on the peat bog, where subfossil trunks were found at the silty gyttja/peat limit. probably also the sandy intercalation reported by fedenya et al. (1992) in the paleochannel fill were laid down from the same flood phase (fig. 4). the upward sediments of lpaz pinus-quercusalnus (3.35-2.90 m deep), dated to 2700-1200 bp, show pinus rise, high quercus (8.4%) and alnus (47%), tilia decline and carpinus disappearance. nap are dominated by polypodiaceae. some sediment samples from 3.25-3.10 m deep were very low in pollen for the alternating peat and sandy laminae were severely affected by erosion and undulation. at 3.20-3.15 m depth polypodiaceae increases and the hygrophytes sphagnum, mentha longifolia and rubiaceae are weakly, though significantly, represented. the subfossil trunks, 15 to 20 cm in diameter, at the boundary between the laminated layer and the overlying peats (fig. 4) mark a further phase of trees fallen on the peat bog caused by increased humidity. all the above features, along with the lack of human activity pollen 175river response to the holocene ... markers, point out an enhanced flood frequency during the humid climatic phase in roman time (c. 2000 bp). tentatively, also the second sandy intercalation reported from the paleochannel fill by fedenya et al. (1992) could be correlated with this flood phase (fig. 4). the uppermost peats (lpaz pinus-picea-corylus, 2.90-2.75 m deep) display scant ulmus and carpinus, expansion of pinus, picea and corylus, decline of quercus robur and desappearance of q. petraea. the picea peak (11.4% at c. 1000 yr bp) records a cooler and more humid climate. the higher humidity in the peat bog is also supported by the occurrence of sparganium, typha latifolia, nuphar and the algae pediastrum. the re-appearance of artemisia, brassicaceae, cichoriaceae, poaceae, calluna and centaurea cyanus along with the peak of corylus indirectly reflect the human presence. probably the exploitation of the deciduous wood contributed to spread the hazel. frequent floods, triggered by climate fluctuations, significantly changed the sedimentation pattern in the paleochannel and the peat growth, definitely over at 885±50 yr bp (rome-1340), was substituted for by accumulation of horizontal bedding, sandy-silty overbank deposits. these latter, up to 1 m in thickness, were blanketed during the last centuries by c. 1.8 m of aeolian sands and podsol developed at their top (fig. 4). the new findings contrast with some conclusion after fedenya et al. (1985, 1992). based on the mammalian assemblage the channel, active during the late atlantic/subboreal transition, was cut off at c. 4200 bp. despite of that the sandy intercalations in the organic sediments point out that episodic oxbow lake/river channel interactions did last over further hundred years. the signature of two humid climatic phases in the paleochannel organic fill (c. 3000 and c. 2000 bp) is provided by re-appearance of hydrophile taxa, trees fallen and sedimentation change in the peat bog. then, a further flood phase (c. 885 yr bp) caused the peat bog burial by overbank deposits. the forest clearing recorded by pollen data at c. 3000 bp likely reflects the impact of the neman culture settlements. however, it is reasonable that the origin of the thick cover of aeolian sands on the middle flood plain near the valley scarps only depended upon the extensive forest exploitation during the last centuries. piaski-bridge the section (fedenya et al., 1992) displays middle-coarse sands with detritus overlain by peats and sands (fig. 3 and 4). previous palaeobotanical and palaeoentomological data bracket the origin of the paleochannel peats between the second half of the atlantic and the beginning of the subatlantic. the new pollen spectrum for piaski-2 (fig. 5) conflicts with the previously stated timing of betula decline and corylus appearance and set the cut off at the boreal/atlantic boundary. further, the important sedimentation change marked by the sudden appearance of fine, humified sands in the upper part of the sequence (fig. 4, profile 1), previously placed at the subboreal/ subatlantic limit by the picea peak, is more reliably 176 fig. 8 geological section a-b (see fig. 3) of the study area (i) and schematic profile (ii) across the zelvianka river valley near piaski (by t. kalicki) 1 – bedrock (tilt with glaciodislocated chalk), 2 – limnoglacial serie with slump, 3 – gravel with sand, 4 – sand, 5 – eolian sand, 6 – intercalation of sand and sandy silt, 7 – sandy silt, 8 – intercalation of sand and organic sandy silt, 9 – organic sand, 10 – organic sandy silt, 11 – intercalation of peat and sand, 12 – sandy peat, 13 – peat, 14 intercalation of sand and gyttja silt, 15 – gyttja silt, 16 – gyttja, 17 – buried soil, 18 – subfossil trees and detritus, 19 – bones, 20 flint artifacts, 21 – palaeobotanical, palaeozoological and archaeological datings, 22 – radiocarbon datings; al – alleröd, yd – younger dryas, pb – preboreal, bo – boreal, at – atlantic, sb – subboreal, sa subatlantic. t. kalicki, g. calderoni & v. zernitskaya dated at c. 1000 bp by the spruce maximum shown in both the previous pollen diagrams for this profile and in the new one from piaski-1 (fig. 7). piaski-9 the overall features of this new section (2.2.-2.5 m a.r.l.) are as for piaski-10 (fig. 3 and 6). the fine sands at the bottom of the paleochannel fill change upward into organic sediments, with a gyttja layer, dated at 3245±60 yr bp (rome-1342), at the base. through the upward 80 cm a regular alternation of a few mm thick, brown and whitish laminae is shown. the former ones, rich in organic matter, deposited during the vegetational seasons whereas the latter ones, made up by fine sands, during the spring floods. in our knowledge such an evidence of seasonal sedimentation change in paleomeanders was never reported. as the frequency of the laminae pairs is from 5 to 7 cm-1, it can be estimated that the whole member deposited in some 500 yrs. such peculiar lamination is overlain by sands with silty-sands intercalations. paleogeography the origin of zelvianka river valley dates back to the disappearance of the dammed skidel lake in the young pleniglacial, just after the pomeranian stage of the last glaciation dated to 16.2 (kozarski, 1995) and 15.5-15.0 ka bp (valchik, 1992). the incision of neman river and its tributaries on the upper neman plain was over in middle lithuanian stage of deglaciation (13.813.7 ka bp, valchik, 1992), when zelvianka river bifurcated near piaski and meanders, still well preserved downstream of the study site, were confined. the young pleniglacial incision of the limnoglacial sediments was so fast that the bottom level of the late glacial paleomeanders (e.g., piaski-2, -5 and -10) approach those of their holocene analogues (fig. 8). the vegetal macrofossils from the channel deposits (piaski-5) date the upper flood plain at the alleröd. a fast incision, followed by a relative stabilization, was also reported from the main neman river valley, where the terrace t-1 and the upper flood plain formed during the late glacial and the early holocene, respectively (vozniachuk and valchik, 1978). during the younger dryas the highlands were covered by pine-birch-juniper open forests, the humid lows by spruce and dwarf birch (betula nana) and the open lands by xerophyte grass communities. the climate cooling forced changes of zelvianka river course and the cut off occurred at the alleröd/younger dryas transition (e.g., piaski-2, 10,670 bp). evidence of river braiding, lateral migration and valley widening are the relatively shallow paleochannels (with subfossil trunks in their fills) that while undercutting caused slumps on the slope of the northern branch of the valley (piaski-2 and -5). probably some river aggradation took place, as the bottom of the river bed rose from c. 0.5-1.0 to c. 1.5 m a.r.l. from the younger dryas to the end of the preboreal (fig. 8). willows as pioneer taxa grew on the new bars of the alluvial plain and also around the oxbow lakes. these latter experienced a highly variable rate and pattern of sedimentation (e.g., fast gyttja accumulation at piaski-2 or slow deposition of sands with detritus at piaski-5). the overall climate warming at the onset of the preboreal is marked by vegetation changes, e.g., spreading of pine forests on the highlands and elms on zelvianka flood plain. some paleochannels (piaski-5) were filled up quickly with sandy sediments containing detritus. at the end of the preboreal (pb-2) the region was covered with birch, pine-birch and elm forests. the shallow paleochannel piaski-10 was cut off at c. 9270 bp. the evolution of zelvianka river bed, as well as the lack of incision likely depended upon the relatively dry climate. elm rise, oak and hazel first appearance, increased the heterogeneity of the mixed forests and development of alder and fern patches on the humid flood plain took place in the boreal. an incision phase of the river at the beginning of the boreal is suggested by the mammal bone assemblages from the channel deposits of the middle flood plain, dated at the preboreal/boreal transition (piaski-4 and -5) and at the onset of the atlantic (piaski-3). likely, the event was caused by a wave of headward erosion originated in the neman valley on the middle neman plain, about 100 km downstream of the study area, prior to the older dryas (kalicki, 2002; kalicki et al., 2002). however, the middle holocene age of the bones from the channel deposits of the 1.5 m high borodnichanka valley bottom in the volkovysk upland (fedenya and kalinovskiy, 1981) points out that the regressive incision reached the upper section of the zelvianka tributaries just in the neoholocene. the cutting, coupled with the improved drainage of zelvianka upper flood plain, changed the former oxbow lakes into peat bogs at c. 9000 bp (piaski-2). in turn, the ephemeral lakes with gyttja accumulation in the preboreal abandoned channels were substituted for by marshes with meadow ore formation (piaski-10) just after 9270 bp. the oldest paleomeanders of the middle flood plain cut off at the boreal/atlantic transition (piaski-bridge) and the bottom height of their fillings equalled the present river water level (fig. 8). reasonably the channel changes were triggered by the humid and cooler climatic phase at the boreal/atlantic transition previously reported from central european river valleys and other environments (starkel et al., 1996; starkel, 2000). in the atlantic pine forests with birch there were confined in the poorest sandy soils, deciduous forests with hazel, elm and subordinate oak, lime and ash spread on the fertile flood plain. and alder and fern occurred in humid sites. the lateral river migration destroyed, completely or partly, some older paleochannel fills (piaski-5). then, in the middle atlantic the younger piaski-5 paleomeander was cut off and fast infilled with sands. both channel changes and a fast sedimentation rate point to frequent floods during the humid climate phase revealed by piaski-2 pollen diagram. this climate trend is consistent with the c. 6420 bp humid phase in the neman valley (kalicki et al., 2000) and the c. 6500-6000 bp climate cooling and increased river activity in the vistula river valley (kalicki,1991b, 1996a; starkel et al., 1996). the bones of middle holocene age from the channel deposits of the southern branch of zelvianka valley (piaski-mill) suggest that since the end of the atlantic only the northern branch was active. the 177river response to the holocene ... late atlantic drier climate, argued from the palaeozoological data from piaski-mill, accounts for the abandonment of the southern valley branch in response to the decreased river discharge. accordingly, the late atlantic/subboreal bones in the channel river facies of the paleomeander undercutting the valley slope at piaski-1 support a widening of the active northern branch of the river valley. in some paleochannels (e.g., piaski-5) the late atlantic increased fluvial activity changed the sedimentation pattern from organic into clastic. climate cooling at the beginning of the subboreal deteriorated the elm forests which were progressively substituted for by oak-pine forests. despite that at c. 4195 bp the meander was cut off at piaski-1, the sandy layers intercalated in the organic fill of the paleomeander reveal that some river/oxbow lake communication did still last over some hundred years. the modern vegetation subzone (carpineto-querceto-pinetum forest) began to develop during the 4000-2700 bp timespan. hornbeam, spruce, beech, birch and alder expanded whereas pine declined. contemporary is the first evidence of settlements, referred to late neolithic (neman culture) and bronze age (trzciniec culture). likely, the local anthropogenic impact resulted in spreading of bush (sambucus, viburnum, rubus), rural and grasslands taxa (piaski-1) and aeolian processes development. in the subboreal and the subatlantic the deposition of wind blown sands, interrupted by pedogenetic phases, covered both flood plain steps near the edge of the valley bottom (piaski-5, -4 and -1). flint artifacts and charcoal from the paleosols (piaski-5) support that the aeolian activity was triggered by the human impact. a humid climatic phase at c. 3000 bp, implying re-appearance of hydrophilous taxa, fallen trees and sedimentation change in the peat bog, was recognized at piaski-1 in the paleochannel organic fill. despite of some anthropogenic overshadowing, this climatic phase is reliably marked by a rise of spruce, appearance of fir in the forests and also by channel changes at 3245 bp (piaski-9). as this phase of enhanced river activity matches those reported from other river valleys in belorussia (kalicki, 1991a; kalicki et al., 1997a, 2000) and central europe (kalicki, 1991b, 1996b) it is better accounted for by significant, large-scale climatic changes (kalicki, 1995, 1996a) rather than the local forest clearing at c. 3000 bp. in the subatlantic (2700-1200 bp) quercus petraea and carpinus disappeared and declined, respectively, in the carpineto-querceto-pinetum forests, whereas alder spread on the flood plain. the subatlantic incision which formed the lower flood plain also deepened the ground water table and thus pedogenesis developed atop the peat bogs on the upper flood plain (piaski-2). the neighborhood of the river, with steady regime and spring floods since the onset of the subatlantic, is witnessed by a series of laminated sediments in the late subboreal abandoned channel (piaski-9). in the roman time (c. 2000 bp) a distinct humid phase is marked by re-appearance of hydrophyte taxa and occurrence of subfossil trees (piaski 1) in the paleochannel organic fill, while both the flood plain higher steps were inundated. the floods are marked by sandy intercalations in the paleochannel fill on the middle flood plain (piaski-1) and sedimentation changes in the abandoned channel on the upper flood plain. here the peat bog was covered with overbank deposits at c. 2085 bp (piaski-2). a further cool and humid climatic phase at 1200-800 bp is suggested by spruce and hazel rise and oak decline. the hydrophilous taxa in the peats from piaski-1 paleomeander point to some input of flooded pollen: then, at c. 885 bp, the peat bog was buried by overbank deposits. almost contemporary (c. 1000 bp) is the burial of the peats by clastic deposits in the abandoned piaski-bridge channel. these two flood phases, likely triggered by climatic changes (kalicki 1996a), are also known from other belorussian (kalicki 1991a, 1995, kalicki et al., 1997b, 2000, kalicki and sanko, 1998) and central european river valleys (kalicki, 1996b, starkel et al., 1996). their identification relied on channel changes (meander cut-offs and avulsions), sedimentation pattern changes on the flood plains (beginning of peat aggradation, peats and soils burial by overbank deposits, abundant tree trunks in alluvia, etc.). based on the above it is inferred that the local forest clearing can only account for the subatlantic aeolian activity which originated the paleosol at piaski-4. conclusions the new 14c dated pollen diagrams from zelvianka river valley and the up to date palynostratigraphic framework for belorussia (zernickaja, 1998, zernitskaya, 1999) pointed out the need to revise the previous pollen chronostratigraphies (fedenya et al.,1992; ivanov, 1993; ivanov and yelovicheva, 1997). most important, it has been pointed out that the atlantic is hardly recognized only by the deciduous taxa peak, hornbeam and beech included. the rejuvenation of the drainage network on the upper neman plain and the lowering of the level of the skidel dammed lake, caused by the vistulian ice-sheet retreat, were almost coeval . the fast young pleniglacial incision also propagated in other river valleys developed at the ice sheet front (kalicki et al., 1997b). thus, the zelvianka river level was almost steady from the late glacial through the holocene. akin to western dvina river valley on the surash plain (kalicki et al., 1997b), the study area is too far from the sea coast to correlate the young pleniglacial, boreal/atlantic and the subatlantic phases of zelvianka river incision with the baltic sea level changes as previously claimed (kovbasyuk and ivanov, 1998). the first two headward erosion phases caused by deglaciation were delayed and smoothed relative to the main neman river valley, thus resulting in small height differences among the three zelvianka river flood plains. the extremely complex structure of the valley bottom depended mostly on the lateral migration of zelvianka river during the holocene. impressively, almost each morphological level with paleomeanders includes numerous, age-distinct alluvial bodies. both channel and sedimentation changes in zelvianka river valley cluster at al/yd transition, c. 9300 bp, bo/at transition, middle atlantic, c. 4200 bp, c. 3250-3000 bp, roman time (2100 bp) and 1000-900 bp. most of these events, likely triggered by the lateglacial and holocene humid and cool climatic phases, fairly match episodes of enhanced river activity in belorussia and central europe. the only noticeable 178 t. kalicki, g. calderoni & v. zernitskaya effect of the human impact on the evolution of the zelvianka river valley is the activation of aeolian processes in deforested areas during the subboreal and 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. paläoklimaforschung 14, 89-100. kalicki, t. 1996a climatic or anthropogenic alluviation in central european valleys during the holocene. in branson, j., brown, a.g. and gregory, k.j. editors, global continental changes: the context of palaeohydrology. geol. soc. special publ. 115, the geological society, london, 205-215. kalicki, t. 1996b phases of increased river activity during the last 3500 years. in starkel, l. and kalicki, t. editors, evolution of the vistula river valley during the last 15 000 years, part vi. geogr. stud. special iss. 9, 94-101. kalicki, t. 2002 transformacja systemu fluwialnego niemna u schy l ku plejstocenu. abstract of symposium transformacja systemów fluwialnych i stokowych w późnym vistulianie i holocenie. 2527.09.2002 lóźdz-uniejów, 15-17. kalicki, t., litwinjuk, g.i., sańko, a.f., szalabuda, w.l., zernickaja, w.p., komarowski, m.e., kalkowski, w.m. and pawlawa, i.d. 2000 dolina niemna na nizinie górnoniemeńskiej. in papers of symposium problemy paleogeografii późnego plejstocenu i holocenu, materialy bia lorusko-polskiego seminarium. wycieczki terenowe 26-29.09.2000, grodno, bialorus, 110-123. kalicki, t. and sanko, a.f. 1998 palaeohydrological changes in the upper dneper valley during the last 20,000 years (belarus). in benito, g., baker, v.r. and gregory, k.j. editors, palaeohydrology and environmental change, chichester, wiley, 125135. kalicki, t., sanko, a.f. and litvinjuk, g.i. 1997a zapis późnoglacjalnych i holoceńskich zmian klimatu i dzia lalności cz l owieka w osadach dna i zboczy doliny ptyczy ko lo mińska. in kalicki, t. editor, badania ewolucji dolin rzecznych na bia lorusi. i, dokumentacja geograficzna 6, 83-104. kalicki, t., sanko, a.f., zernicka, v.p. and litvinjuk g.i. 1997b ewolucja doliny dźwiny na nizinie suraskiej w późnym glacjale i holocenie. in kalicki, t. editor, badania ewolucji dolin rzecznych na bialorusi i, dokumentacja geograficzna 6, 13-52. kalicki, t., zernitskaya, v.p. and simakova, g.i. 2002 late glacial–early holocene development of the niemen valley near goza (belarus). field symposium on quaternary geology and geodynamics in belarus. 20-25.05.2002 grodno, 22-23. kovbasyuk, t.g. and ivanov, d.l. 1998 osobennosti stroyeniya i istoricheskogo razvitiya doliny reki zel’vianki. aktual’nyye problemy estestvoznaniya, 42-47. 179river response to the holocene ... kozarski, s. 1995 deglacjacja pó lnocno-zachodniej polski: warunki środowiska i transformacja geosystemu (~20ka➝ 10ka bp), dokumentacja geograficzna 1. kvasov, d.d. 1976 paleogidrologiya vostochnoy yevropy v valdayskoye vremia. in problemy paleogidrologii, moskwa, nauka, 260-266. kvasov, d.d. 1982 the late quaternary history of the volga river. in paleohydrology of the temperate zone i, rivers and lakes, 43-55, tallin. levkov, e.a. 1980 glaciotektonika, minsk. levkov, e.a., ljudwig, a.o. and karabanov, a.k. 1988: o roli termokarstowykh processov v formirovanii gidroseti i vremeni ischeznoveniya mnogoletnemerzlykh porod na territorii belorussii. doklady an bssr, 32, 4, 343-346. mangerud, j., andersen, s.t., berglund, b.e. and donner, j.j. 1974 quaternary stratigraphy of norden, a proposal for terminology and classification. boreas 3, 109-128. pokrovskaya, i.m. 1950 pyl’tsevoi analiz,. moskva. ralska-jasiewiczowa, m. and lata lowa m. 1996 poland. in: berglund, b.e., birks, h.j.b., ralskajasiewiczowa, m. and wright, h.e. editors, palaeoecological events during the last 15,000 years. chichester, 403-472. starkel, l. 2000 8500-8000 yrs bp humid phase – global or regional? science reports of tohoku university, 7th series, geography, 49, 2, 105-133. starkel, l., kalicki, t., krapiec, m., soja, r., gebica, p. and czyz· owska e. 1996 hydrological changes of valley floor in the upper vistula basin during late vistulian and holocene. in starkel, l. and kalicki, t. editors, evolution of the vistula river valley during the last 15 000 years, part vi, geogr. stud., special iss. 9, 7-128. wasylikowa, k., starkel, l., niedzia lkowska, e., skiba, s. and stworzewicz, e. 1985 environmental changes in the vistula valley at pleszów caused by neolithic man. przeglad archeologiczny 33, 19-55. valchik, m.a. 1992 razvitie dolinno-rechnoy seti belorussii i pribaltiki v sviazi s degradaciey valdayskogo lednikovogo pokrova. in. shirokov l. m. editor, gidrographicheskaya set’ belorussii i regulirovanie rechnogo stoka. minsk, universitetskoye, 3-10. vozniachuk, l.n. and valchik, m.a. 1978 morfologiya, stroyenie i istoriya razvitiya doliny nemana w neoplejstocene i golocene, minsk. zernickaja, w.p. 1998 ogólne i regionalne rozbiez· ności w polodowcowej historii lasów bia lorusi i polski. in kalicki, t. editor, abstract of symposium paleogeografia górnego plejstocenu i holocenu wschodniej polski i bia lorusi, streszczenia referatów, posterów i przewodnik wycieczki, 5-7.10.1998 kraków, 58-59. zernitskaya, v.p. 1999 stratigraphy of the late-glacial and holocene of belorussia. problems and methods of modern regional stratigraphy. abstracts of the 4 th baltic stratigraphical conference, 27-30.09.1999, riga , 112-113. zernitskaya v.p., mikhailov n.d., simakova g.i., kolkovsky v.m. and luchina g.i. 2003 radiocarbon dating and palynostratigraphy of late glacial and holocene deposits of belarus. in stratigraphy and palaeontology of geological formation of belarus. minsk, 129-134. 180 ms. ricevuto il 22 giugno 20024 testo definitivo ricevuto il 2 novembre 2004 ms. received: june 22, 2004 final text received: november 2, 2004 t. kalicki, g. calderoni & v. zernitskaya impaginatoinsinga ssttrraattiiggrraaffiiaa ee ccaarraatttteerriissttiicchhee ffiissiicchhee ddeeii ddeeppoossiittii oolloocceenniiccii ddeell ppoorrttoo ddii mmiisseennoo,, ggoollffoo ddii ppoozzzzuuoollii ((ttiirrrreennoo cceennttrroo--oorriieennttaallee)) dd.. iinnssiinnggaa 11**,, aa.. ddii mmeegglliioo 22,, ff.. mmoolliissssoo 11 && mm.. ssaacccchhii 11**** 1 istituto di ricerca geomare sud cnr, via amerigo vespucci, 9 80142 napoli 2 technodata s.r.l., via cinthia, p.co s. paolo, is. 20 80126 – napoli *insinga@gms01.geomare.na.cnr.it; **sacchi@gms01.geomare.na.cnr.it riassunto l’analisi di cinque carotaggi profondi (30÷40 m) effettuati nello specchio d’acqua del porto di miseno (settore occidentale dei campi flegrei), insieme con la datazione di due livelli di torba (14c ams) ed una serie di prove geotecniche in sito e su campioni indisturbati, ha consentito di ricostruire l’assetto stratigrafico della successione olocenica campionata al di sotto del fondo mare e di determinare le caratteristiche fisiche e meccaniche dei sedimenti. sulla base dei risultati ottenuti sono state delineate le principali fasi evolutive di questa piccola insenatura del golfo di pozzuoli durante gli ultimi 10.000 anni. la successione carotata, costituita prevalentemente da sabbie di natura vulcanica, è caratterizzata da un trend generale trasgressivo localmente interrotto da due episodi di regressione forzata legati al rapido accumulo di depositi piroclastici più o meno sviluppati. gli episodi regressivi terminano con la formazione di due livelli di torba rinvenuti all’interno dell’unità b ed al passaggio tra le unità d ed e, e le cui misure radiometriche hanno fornito un’età di 3560±40 anni e 7815±55 anni, rispettivamente. ciò permette di correlare tali livelli con due importanti fasi di quiescenza dell’attività vulcanica dei campi flegrei documentate in letteratura. il controllo geocronologico fornito dalle datazioni assolute, consente, inoltre, una stima dei tassi di sedimentazione durante l’olocene medio-superiore, i quali sono mediamente dell’ordine di 3.5 m/ka per le unità inferiori (e-d) e di 2.2 m /ka per quelle superiori (b-a). la successione olocenica di porto miseno può essere correlata con una serie di unità sismo-stratigrafiche individuate nel settore centrale ed in quello orientale della piattaforma continentale del golfo di pozzuoli e con la sezione affiorante lungo la scarpata d’erosione del terrazzo marino de la starza, nel settore emerso dei campi flegrei, dove la successione olocenica è stata sollevata di circa 40 m sopra il livello del mare durante gli ultimi 4000 anni. abstract the stratigraphic study of five deep cores (30-40 m) drilled in the harbor of miseno (western flegrean fields), along with radiometric age dating (14c ams) of two peat layers and a number of geotechnical tests, allowed for the reconstruction of the stratigraphic framework and the determination of physical and mechanical properties of the holocene succession beneath the sea floor. based on these data we outline the evolution of the study area during the last 10.000 years. the holocene succession of porto miseno is characterized by transgressive volcanic sandy deposits which include a 1÷5 m thick pyroclastic unit (unit c). two resting phases, which closes regressive episods, are testified by two peat layers which have been cored within unit b (layer t1) and at the transition between units d and e (layer t2). samples collected from the peat layers yielded radiometric ages of 3560±40 years b.p. and 7815±55 years b.p., respectively. this suggests a correlation between the cored peat layers and two paleosols documented on land that are associated with resting periods during the volcanic activity of flegrean fields. chronostratigraphic constraints, based on these radiocarbon age determinations, allowed for the evaluation of sedimentation rates during late holocene, which are in the order of 3.5 m/ka for the lower units (e-d) and 2.2 m /ka for the upper part of the section (units b-a). the holocene deposits of porto miseno can be correlated with distinct seismic-stratigraphic units identified in the subsurface of the southern and central sectors of pozzuoli bay. they can be also correlated with the section cropping out onshore, along the erosional slope of “la starza” terrace, where the marine holocene sequence has been uplifted about 40 m above the sea level in the last few thousand years. parole chiave: golfo di pozzuoli, campi flegrei, olocene, caratteristiche geotecniche, età radiometrica key words: pozzuoli bay, flegrean fields, holocene, geotechnical properties, radiometric age. il quaternario italian journal of quaternary sciences 1155(1), 2002, 11-21 11.. iinnttrroodduuzziioonnee il settore costiero del mar tirreno centro-orientale è caratterizzato dalla presenza diffusa di resti archeologici e di strutture portuali di età classica greca e romana (ca 2000-3000 anni b.p.) che si rinvengono oggi per lo più sommersi o, comunque, a quote differenti rispetto a quelle della loro originaria realizzazione ed ubicazione funzionale. ciò a testimonianza di importanti variazioni che hanno interessato il livello relativo del mare e la linea di costa della campania (alessio et al., 1994), in particolare nel settore dei campi flegrei, nel corso delle ultime decine di centinaia di anni (dvorak & mastrolorenzo, 1991). diversi studi dimostrano che circa 2000 anni fa il livello del mare era all’incirca 0.5 m più basso di quello attuale e che poi è rapidamente risalito con tassi di circa 0.75 mm/anno tra il 50 b.c. e l’a.d.150 (pirazzoli, 1976). un’ulteriore complicazione per la ricostruzione degli spostamenti della linea di costa nell’area oggetto di studio durante l’olocene è rappresentata poi dalla notevole instabilità tettonica dell’area circostante l’abita12 insinga et al. to di pozzuoli, la quale è stata interessata, anche in epoca storica, da ripetute e talora drammatiche fasi di sollevamento e di subsidenza (barberi et al.,1984). nel settore settentrionale del golfo di pozzuoli compreso tra baia e punta miseno si rinvengono frequentemente manufatti, resti di reperti o costruzioni di età romana (ville, piscine e banchine d’attracco) ad una profondità compresa tra i 9 ed i 7 m al di sotto del livello medio del mare (caputo, 1989). per l’area dell’attuale porto di miseno (comune di bacoli), già base della flotta imperiale romana dal i al iv secolo d.c., è stato calcolato un innalzamento relativo del livello del mare, in gran parte imputabile a subsidenza tettonica, di circa 9 m negli ultimi 2000 anni (dvorak & mastrolorenzo, 1991). tra il vii ed l’xi sec., nel periodo di massima ingressione marina, legata a fenomeni di bradisismo, si registrano massimi di subsidenza dell’ordine di 11-12 m (cinque et al., 1991). nel corso del 1998, l’istituto di ricerca “geomare sud” del cnr di napoli ha svolto una serie di campagne di indagini dirette ed indirette al fine di ricostruire la stratigrafia dei depositi olocenici nei golfi di napoli e di pozzuoli (aiello et al., 1999; 2000). in particolare, nell’area di porto miseno, a sud dell’abitato di pozzuoli, sono stati effettuati cinque carotaggi profondi, di cui uno a terra e quattro nello specchio d’acqua antistante la banchina, che hanno raggiunto una profondità massima di 34 m al di sotto del l.m.m. l’esecuzione dei carotaggi è stata accompagnata da una serie di prove geotecniche sia in sito che in laboratorio e dalla determinazione dell’età radiometrica (14c ams) di due campioni di torba che hanno consentito di inquadrare la successione studiata da un punto di vista cronostratigrafico. la granulometria mediamente grossolana dei depositi carotati e le tecniche di perforazione adottate, non hanno consentito il recupero di campioni sufficientemente indisturbati per il riconoscimento delle strutture sedimentarie minori, le quali sono state in parte obliterate nel corso delle operazioni di carotaggio. e’ stato possibile, tuttavia, ricostruire l’esatto spessore stratigrafico fig. 1. schema vulcano-tettonico dei campi flegrei e del golfo di pozzuoli con l’ubicazione del porto di miseno e dell’area studio (modificato da rosi & sbrana, 1987; milia, 2000). volcano-tectonic sketch map of the flegrean fields and pozzuoli bay showing the location of porto miseno and the study area. dei diversi depositi incontrati ed il recupero di segmenti di carota, anche di considerevole lunghezza, pressoché indisturbati. ciò ha permesso non solo di ricostruire l’assetto litostratigrafico della successione campionata, ma anche di delineare le principali fasi evolutive di questa piccola insenatura nel corso degli ultimi 10.000 anni. 22.. iinnqquuaaddrraammeennttoo ggeeoollooggiiccoo l’area di porto miseno ricade nel settore occidentale del distretto vulcanico dei campi flegrei che si sviluppa in corrispondenza di un alto morfostrutturale del basamento meso-cenozoico del margine occidentale dell’appennino campano (fig. 1). l’attività vulcanica dei campi flegrei è legata alla tettonica distensiva che ha interessato il margine tirrenico orientale durante il quaternario e di cui la piana campana ed il golfo di napoli rappresentano alcuni tra i principali elementi morfotettonici (ippolito et al.,1973; ortolani & aprile, 1978; milia, 1996; aiello et al., 1999). dall’inizio della sua attività (c.a.50.000 anni b.p.), questo distretto è stato caratterizzato da una serie di manifestazioni vulcaniche e dallo sviluppo di numerosi centri eruttivi monogenici con chimismo ad affinità potassica (di girolamo et al., 1984). uno degli elementi strutturali più caratteristici dell’area dei campi flegrei è rappresentato da una depressione ampia 12 km (orsi et al., 1996), comunemente interpretata come il risultato dell’evoluzione di un sistema calderico, all’interno della quale si è manifestata gran parte dell’attività vulcanica recente conclusasi con l’eruzione del monte nuovo nel 1538 a.d. (di vito et al., 1987). l’andamento dell’originale bordo calderico è individuabile a terra in corrispondenza di una serie di scarpate discontinue alte diverse decine di metri, mentre nel settore sommerso, a sud del golfo di pozzuoli, coincide probabilmente con i banchi vulcanici di miseno, nisida e penta palummo (colantoni et al., 1972; pescatore et al., 1984; milia, 1998) l’attività vulcanica di tipo esplosivo nell’area di miseno si è esplicata prevalentemente tra 12.0 e 9.5 ka b.p. (i epoca, di vito et al., 1999) ed ha determinato lungo il bordo della struttura calderica, la formazione di “tuff rings” e “tuff cones” di cui porto miseno e capo miseno rappresentano alcuni relitti rispettivamente. questi apparati di modeste dimensioni, pur essendo oggi quasi completamente distrutti a seguito di collassi vulcano-tettonici e dell’erosione marina che hanno interessato il settore costiero in esame nelle ultime migliaia di anni, conferiscono all’area i tratti caratteristici di un sistema craterico collassato. in particolare, l’originaria morfologia è ancora riconoscibile nella forma circolare dell’insenatura del porto di miseno. i suddetti apparati vulcanici sono costituiti principalmente da alternanze di strati di scorie di varie dimensioni miste a pomici immerse in una matrice cineritica più o meno abbondante ed a luoghi resa coerente da un processo di diagenesi e di cementazione secondaria (zeolitizzazione). in alcune zone, lungo i versanti di questi apparati vulcanici sono visibili, infatti, graduali passaggi da facies piroclastiche giallastre litoidi a facies grigiastre notevolmente meno coerenti. 33.. iinnddaaggiinnii eesseegguuiittee ee ddaattii rraaccccoollttii la campagna di indagini è consistita in una serie di prove sia in sito che in laboratorio. queste hanno permesso di ricostruire l’evoluzione stratigrafica dell’area, di caratterizzare da un punto di vista geotecnico i depositi campionati e di datare con il metodo del radiocarbonio due livelli di torba recuperati dai campioni di carotaggio. in figura 2 è indicata l’ubicazione dei cinque carotaggi realizzati, mentre in tabella 1 sono indicati, per ciascuno di essi, le quote di boccaforo riferite al livello medio del mare, le profondità raggiunte, il numero dei campioni indisturbati prelevati ed il numero di prove penetrometriche eseguite. 3.1. carotaggi i carotaggi, denominati con la sigla mgf, hanno raggiunto una profondità massima di 40 m, per una lunghezza complessiva di perforazione effettuata di circa 170 m ed una percentuale di recupero di circa 76 %. per il recupero dei campioni sono state utilizzate attrezzature a rotazione munite di carotiere semplice del diametro esterno di 101 mm ed adoperate, dove necessario, 13stratigrafia e caratteristiche fisiche... fig. 2. ubicazione dei cinque carotaggi effettuati in località porto miseno utilizzati in questo studio (mgf 1-mgf 5). location of five cores drilled in the porto miseno area (mgf 1-mgf 5) analyzed in this study. 14 colonne di rivestimento del diametro esterno di 127 mm. per i carotaggi effettuati in mare (mgf 2-5) si è operato da un pontone galleggiante, munito di mensola a sbalzo per facilitare le operazioni di montaggio delle aste ed il recupero del sondaggio. dai fori di trivellazione è stato estratto un carotaggio più o meno continuo che, sistemato in apposite cassette catalogatrici, è stato poi utilizzato per la descrizione litostratigrafica. sono stati quindi prelevati una serie di campioni indisturbati adoperando un campionatore tipo shelby, del diametro di 90 mm e della lunghezza di 70 cm, infisso a pressione previo avanzamento del rivestimento e pulitura del foro. nel corso delle operazioni di carotaggio sono state, inoltre, eseguite prove penetrometriche tipo standard penetration test (s.p.t.) i cui risultati vengono riportati in tabella 2. 3.2 analisi granulometriche e prove geotecniche i 25 campioni indisturbati recuperati sono stati sottoposti in seguito ad una serie di prove geotecniche di laboratorio al fine di determinare 1) le caratteristiche fisiche (umidità naturale w, peso dell’unità di volume γ, peso specifico dei granuli γs, porosità n, grado di saturazione s); 2) la distribuzione granulometrica mediante setacciatura (per la parte più grossolana) e sedimentazione (per la frazione più sottile); 3) le caratteristiche meccaniche quali coesione c ed angolo d’attrito interno ϕ, mediante prove di taglio diretto. i risultati delle prove geotecniche di laboratorio sono riportati schematicamente nelle tabelle 3 e 4. 44.. ssttrraattiiggrraaffiiaa ddeeii ddeeppoossiittii oolloocceenniiccii ddii ppoorrttoo mmiisseennoo l’analisi delle colonne stratigrafiche dei carotaggi di porto miseno consente il riconoscimento di cinque unità litostratigrafiche principali, ben definibili e correlabili a cui si intercalano due orizzonti di torba più o meno continui (fig. 3). queste unità sono rappresentate, dal basso verso l’alto da: unità e sabbie grossolane ghiaiose unità d sabbie limose pozzolaniche unità c pomici eterometriche in matrice pozzolanica unità b sabbie medio-grosse incoerenti unità a sabbie fini limose 4.1. unità e sabbie grossolane ghiaiose la parte basale della successione è caratterizzata da sabbie piuttosto grossolane, a tratti ghiaiose, con ciottoli lapidei poligenici, di colore grigio, ed abbondanti insinga et al. nnuummeerroo ddii nnuummeerroo ddii ssoonnddaaggggiioo qquuoottaa//pprrooffoonnddiittàà lluunngghheezzzzaa ccaammppiioonnii pprroovvee ((nn°°)) ((mm)) ((mm)) iinnddiissttuurrbbaattii ss..pp..tt.. mgf1 +0,75 34 5 7 mgf2 -1,20 34 5 7 mgf3 -1,50 30 5 6 mgf4 -2,00 32 5 7 mgf5 -2,50 40 5 7 ssoonnddaaggggiioo pprrooffoonnddiittàà pprroovvee ss..pp..tt.. ((nn°°)) ((mm)) ((nnsspptt)) mgf1 4,6 16 mgf1 8,0 33 mgf1 14,0 31 mgf1 18,4 25 mgf1 20,5 66 mgf1 25,6 r mgf1 34,0 70 mgf2 4,0 70 mgf2 8,0 60 mgf2 11,5 24 mgf2 15,5 7 mgf2 20,0 r mgf2 26,5 7 mgf2 34,0 31 mgf3 4,0 20 mgf3 8,0 43 mgf3 12,0 51 mgf3 16,0 30 mgf3 25,0 r mgf3 27,5 r mgf4 4,0 16 mgf4 8,0 21 mgf4 11,5 24 mgf4 16,0 59 mgf4 20,1 43 mgf4 26,6 37 mgf4 30,0 r mgf5 4,0 13 mgf5 8,0 23 mgf5 11,5 41 mgf5 16,0 55 mgf5 20,0 55 mgf5 27,5 26 mgf5 35,0 r tab. 1 quadro sintetico di quote di boccaforo, profondità raggiunte, numero di campioni indisturbati e numero di prove standard penetration test (s.p.t.) per i cinque sondaggi a carotaggio continuo effettuati nel porto di miseno. synopsis of altitude/water depth, length, number of undisturbed samples and number of standard penetration tests (s.p.t.) measurements for the cores mgf drilled in porto miseno. tab. 2. riepilogo dei risultati delle prove standard penetration test (s.p.t.) eseguite nel corso delle operazioni di carotaggio nel porto di miseno. summary of standard penetration tests (s.p.t.) measurements carried out during drilling operations at porto miseno. 15 pomici (grafico e in fig. 4). la presenza di intercalazioni di sottili livelli limosi ha favorito la formazione di un “tappo” di chiusura del tubo campionatore, consentendo il recupero dei depositi in fase di carotaggio. il grado di arrotondamento ed appiattimento dei clasti suggeriscono un ambiente deposizionale di spiaggia prossimale o di battigia. 4.2. unità d sabbie limose pozzolaniche questi sedimenti sono rappresentati da sabbie di colore grigio scuro in matrice limosa di natura vulcanica. la parte alta di questo livello è caratterizzata dalla presenza di materiale organico e da frammenti di gusci di bivalvi e gasteropodi. la parte inferiore, invece, è generalmente più povera in frazione limosa come evidenziato dal grafico d in figura 4. lo spessore carotato può raggiungere i 13 m come accade nei sondaggi mgf 2 e mgf 3. la presenza di una frazione limosa, generalmente sempre apprezzabile, suggerisce condizioni di sedimentazione in ambiente protetto di spiaggia somstratigrafia e caratteristiche fisiche... fig. 3 correlazione litostratigrafica tra i carotaggi mgf del porto di miseno. le età assolute degli orizzonti di torba t1 e t2 sono state determinate datati con il metodo del radiocarbonio. lithostratigraphic correlation among mgf cores, porto miseno. peat horizons t 1 and t 2 have been dated by 14c. 16 mersa. i depositi si presentano generalmente coerenti, oltre che resistenti alla perforazione. 4.3. unità c pomici eterometriche in matrice pozzolanica quest’unità raggiunge uno spessore massimo di 5 m nel carotaggio mgf 1, e si rinviene a profondità comprese tra i 14 ed i 19 m. le pomici, immerse in una matrice sabbioso-limosa di natura vulcanica, hanno dimensioni variabili (5 cm max.) (grafico c in fig. 4) e presentano, talvolta, patine di ossidazione probabilmente legate a processi di alterazione in ambiente subaereo insinga et al. fig. 4 curve granulometriche (di frequenza cumulativa) dei campioni prelevati dai carotaggi effettuati nel porto di miseno (mgf 1mgf 5). granulometric curves (cumulative frequencies) of core samples drilled at porto miseno (mgf 1-mgf 5). 17 o vadoso. la presenza, in tale livello, di granuli (ciottoli) con elevato grado di arrotondamento, suggerisce per questi depositi un ambiente di sedimentazione di spiaggia sommersa prossimale o di battigia. 4.4. unità b sabbie medio-grossolane incoerenti questi depositi clastici grossolani sono poveri in matrice (grafico b in fig. 4) e piuttosto incoerenti. essi costituiscono un’unità di spessore variabile da un minimo di 6 m ad un massimo di 10 m (sondaggio mgf 5). inclusi in tale livello si ritrovano, spesso, clasti pomicei di dimensioni variabili. si tratta dei depositi basali di un breve ciclo marino trasgressivo-regressivo che si sviluppa con una classica successione gradata passando da sabbie medio-grossolane a sabbie medie, debolmente limose, progressivamente più fini procedendo verso l’alto. 4.5. unità a sabbie fini limose rappresentano i depositi stratigraficamente più recenti che da fondo mare raggiungono una profondità media di 6 m (7.50 m nel carotaggio mgf 1 eseguito a terra). queste sabbie di natura vulcanica sono caratterizzate da una notevole presenza di resti di origine vegetale e da piccoli frammenti di gusci di molluschi. talora si ritrovano gusci di lamellibranchi (cardium sp.) ben conservati ed organizzati in veri e propri orizzonti alla base dell’unità (sondaggi mgf 2, mgf 3, mgf 5). queste caratteristiche suggeriscono un ambiente deposizionale di bassa energia di tipo spiaggia sommersa di ambiente protetto. 4.6. torbe gli orizzonti di torba rinvenuti durante le operazioni di carotaggio si ritrovano, rispettivamente, all’interno dell’unità b (orizzonte t1), a profondità comprese tra 8 e 12 m, ed al passaggio tra le unità e e d (orizzonte t2), a profondità comprese tra 26 e 31.5 m (fig.3). l’orizzonte t2 è stato raggiunto nel sondaggio mgf 1 ad una profondità di 31.5 m (campione n° 6444) mentre l’orizzonte t1 è stato carotato nel sondaggio mgf 3 ad una profondità di 9.50 m (campione n° 6445). i campioni prelevati sono stati sottoposti ad analisi per la determinazione dell’età assoluta con il metodo del radiocarbonio. per il campione n° 6444 (t1) è stata ottenuta un’età di 3565±40 anni b.p., mentre il campione n° 6445 (t2) ha fornito un’età di 7815±55 anni b.p. (fig. 3). le età misurate degli orizzonti torbosi t1 e t2 ben si correlano con le età, riportate in letteratura, di due paleosuoli che testimoniano fasi di quiescenza dell’attività vulcanica nel settore occidentale dei campi flegrei durante gli ultimi 10.000 anni (rosi & sbrana, 1987; d’antonio et al., 1999). 55.. ccaarraatttteerriissttiicchhee ffiissiicchhee ee mmeeccccaannii-cchhee ddeeii ddeeppoossiittii oolloocceenniiccii ddii ppoorrttoo mmiisseennoo i risultati ottenuti dalle prove di laboratorio e dalle indagini geotecniche in sito, riportati sinteticamente nelle tabelle 3 e 4 e con i valori medi per ogni unità riconosciuta in tabella 5, hanno fornito dati utili per la caratterizzazione delle proprietà fisiche generali e meccaniche della successione olocenica investigata, rappresentando inoltre un ulteriore criterio utile per la correlazione stratigrafica. in particolare, l’analisi delle curve granulometriche illustrate in figura 4, ha consentito di suddividere la successione di porto miseno in cinque unità litostratigrafiche principali e di evidenziarne i caratteri tessiturali ed i parametri statistici principali. 5.1. unità e sabbie grossolane ghiaiose si tratta di sabbie grossolane caratterizzate da una frazione ghiaiosa piuttosto abbondante (circa il 42%) e dalla presenza di sottili livelli più limosi intercalati che hanno facilitato le operazioni di campionamento. i depositi risultano ben addensati, con valori di nspt molto variabili e compresi tra 27 e 70. tale dispersione è probabilmente legata alle dimensioni medie dei clasti ed alla distribuzione piuttosto eterogenea delle varie classi granulometriche. i pesi dell’unità di volume γ risultano compresi tra 17.65 e 18.63 kn/m3, la porosità n presenta valori medi intorno a 39%, la coesione è nulla, mentre i valori dell’angolo di attrito interno ϕ sono mediamente di 35°. 5.2. unità d sabbie limose pozzolaniche tale livello è costituito da sabbie fini pozzolaniche con una frazione di limo variabile che in alcuni casi raggiunge il 23%. si tratta di depositi apparentemente molto compatti come testimoniato dai risultati delle prove spt eseguite, che hanno registrato valori nspt compresi tra minimi di 34 e massimi fino al rifiuto. le tabelle 3 e 4 mostrano valori di peso dell’unità di volume γ mediamente compresi tra 15.7 e 17.65 kn/m3, un valore medio di 6 kpa per la coesione c, porosità n intorno al 50% ed angoli di attrito interno ϕ tra 35° e 40°. 5.3. unità c pomici eterometriche in matrice pozzolanica tale orizzonte è rappresentato, da un punto di vista granulometrico, da una ghiaia con sabbia limosa. la porosità n di questi depositi è molto elevata (circa il 60%), ed i pesi dell’unità di volume γ si aggirano intorno ai 16.67 kn/m3. lo stato di addensamento è risultato fortemente variabile con valori di nspt compresi tra 8 e 30, mentre la prova di taglio diretto ha registrato angoli di attrito ϕ di 36° e valori di coesione c intorno a 6 kpa. 5.4. unità b sabbie medio-grossolane incoerenti i risultati delle prove di laboratorio indicano che per tali sabbie la frazione ghiaiosa è talora predominante. questi depositi sono dotati di un certo grado di addensamento con valori di nspt mediamente compresi tra 20 e 40, tipici di sabbie da mediamente addensate a dense. i valori del peso di volume γ registrati dalle prove eseguite risultano in media pari a 15.7 kn/m3 con valori minimi e massimi di 14.70 e 18.63 kn/m3 registrati, rispettivamente, in corrispondenza di orizzonti costituiti da pomici e litici. la coesione c misurata presenta un valore medio di 4 kpa, mentre l’angolo di attrito interno ϕ oscilla tra i 33° ed i 38°. 5.5. unità a sabbie fini limose la frazione limosa nelle sabbie fini è più o meno abbondante ed i filamenti vegetali, presenti in quantità considerevoli, conferiscono al complesso una certa stratigrafia e caratteristiche fisiche... compressibilità. le prove spt eseguite hanno fatto registrare valori del numero di colpi nspt compresi tra 12 e 20, caratteristici di terreni da scarsamente a mediamente addensati. dal punto di vista delle proprietà fisiche generali e meccaniche, l’unico campione analizzato in laboratorio ha evidenziato pesi dell’unità di volume γ prossimi a 14.71 kn/m3, valori di coesione c nulli ed angoli di attrito ϕ pari a 35°. 66.. ddiissccuussssiioonnee ee ccoonncclluussiioonnii l’analisi di 5 sondaggi a rotazione con carotaggio continuo (mgf 1 mgf 5), insieme con la determinazione dell’età radiometrica (14c ams) di due livelli di torba rinvenuti nella successione campionata, ha consentito di ricostruire nel dettaglio l’assetto stratigrafico della successione tardo-quaternaria della baia di miseno, nel golfo di pozzuoli, che rappresenta un settore sommerso del distretto vulcanico dei campi flegrei (fig.3). in particolare, l’area del porto di miseno è caratterizzata da una successione olocenica espansa, che è stata investigata fino ad una profondità massima di 40 m, e risulta costituita da una successione di sabbie marine più o meno limose con abbondante frazione vulcanoclastica ed intercalazioni di livelli o strati di depositi piroclastici rappresentati prevalentemente da pomici. lo studio delle campionature, condotto sia sulla base delle caratteristiche litologiche ricavate dalla descrizione dei log di carotaggio, sia utilizzando i risultati dell’analisi granulometrica dei campioni in laboratorio, ha consentito di riconoscere cinque unità litostratigrafiche principali che dal basso verso l’alto sono state distinte con lettere e-a (figg. 3 e 4). 6.1. proprietà fisiche e meccaniche l’analisi delle proprietà fisiche dei campioni ha evidenziato valori piuttosto bassi del grado di saturazio18 insinga et al. ggrraannuulloommeettrriiaa ((%% iinn ppeessoo)) ppeessoo ssppeecciiffiiccoo ppeessoo ddii ggrraaddoo ddii ssoonnddaaggggiioo ccaammppiioonnee pprrooffoonnddiittàà uummiiddiittàà ddeeii ggrraannuullii vvoolluummee ppoorroossiittàà ssaattuurraazziioonnee ((nn°°)) ((nn°°)) ((mm)) ghiaia sabbia limo + argilla ww ((%%)) γγss ((11ee++0033 kkgg//mm33)) γγ ((kknn//mm33)) nn ((%%)) ss ((%%)) 1 1 8,0-8,5 3,22 92,98 3,79 36,13 2,518 17,289 48,58 0,96 1 2 11,5-12.0 48,68 33,43 17,87 46,98 2,481 15,847 55,66 0,92 1 3 18,0-18,4 38,43 33,21 28,35 75,54 2,487 13,631 68,15 0,87 1 4 25,0-25,6 13,47 63,07 23,45 37,68 2,524 18,093 46,90 1,00 1 5 29,0-29,5 0,13 90,65 9,20 38,20 2,552 16,759 51,54 0,91 2 1 6,0-6,4 0,95 92,90 6,13 29,25 2,513 16,573 47,95 0,79 2 2 11,0-11,5 41,9 50,8 7,28 25,80 2,486 15,847 48,32 0,68 2 3 18,0-18,6 3,65 87,09 9,25 40,64 2,467 16,308 52,07 0,92 2 4 26,0-26,5 14,81 62,30 22,87 41,99 2,384 14,778 55,49 0,80 2 5 30,0-30,5 4,06 91,82 4,11 21,58 2,521 19,034 36,66 0,93 3 1 6,0-6,5 0,78 86,58 12,63 26,69 2,491 19,034 38,51 1,00 3 2 10,0-10,6 31,59 63,86 4,54 19,01 2,495 14,641 49,71 0,47 3 3 17,5-17,8 8,73 83,50 7,76 39,27 2,548 17,279 50,34 0,98 3 4 24,5-25,0 0,65 95,57 3,76 56,61 2,384 15,514 57,37 0,99 3 5 29.0-29,3 0,4 88,92 10,66 54,71 2,353 15,592 56,31 0,99 4 1 6,0-6,5 5,54 91,28 3,16 18,73 2,510 14,670 49,81 0,47 4 2 11,0-11,5 21,16 71,58 7,24 26,55 2,478 15,690 48,96 0,68 4 3 18,0-18,6 0,59 95,85 3,54 32,43 2,524 17,416 47,17 0,91 4 4 25,0-25,6 3,98 86,03 9,71 40,98 2,300 15,926 49,89 0,94 4 5 31,0-31,5 0,84 93,46 5,66 22,52 2,523 18,750 37,88 0,93 5 1 4,0-4,5 2,78 94,10 3,10 22,37 2,622 17,563 44,16 0,74 5 2 11,0-11,5 8,17 87,48 4,33 51,03 2,413 15,475 56,69 0,94 5 3 18,0-18,6 3,53 80,87 15,59 35,19 2,507 17,278 48,02 0,95 5 4 25,0-25,5 7,14 79,68 13,17 37,20 2,522 16,709 50,84 0,90 5 5 37,0-37,5 42,33 43,17 14,9 24,65 2,486 17,769 41,52 0,86 tab. 3 risultati delle prove di laboratorio per la determinazione delle proprietà fisiche dei campioni mgf. summary of main physical properties of samples mgf as determined in laboratory. 19stratigrafia e caratteristiche fisiche... ssoonnddaaggggiioo ccaammppiioonnee pprrooffoonnddiittàà aannggoolloo ddii aattttrriittoo ccooeessiioonnee ((nn°°)) ((nn°°)) ((mm)) ϕϕ ((°°)) cc ((kkppaa)) 1 1 8,0-8,5 38 18,0 1 2 11,5-12.0 33 0,0 1 3 18,0-18,4 36 8,0 1 4 25,0-25,6 37 14,0 1 5 29,0-29,5 36 15,0 2 1 6,0-6,4 35 2,0 2 2 11,0-11,5 39 1,0 2 3 18,0-18,6 38 10,0 2 4 26,0-26,5 30 0,0 2 5 30,0-30,5 40 17,0 3 1 6,0-6,5 39 7,0 3 2 10,0-10,6 33 0,0 3 3 17,5-17,8 37 4,0 3 4 24,5-25,0 41 4,0 3 5 29.0-29,3 36 0,0 4 1 6,0-6,5 35 0,0 4 2 11,0-11,5 36 4,0 4 3 18,0-18,6 36 0,0 4 4 25,0-25,6 36 0,0 4 5 31,0-31,5 34 0,0 5 1 4,0-4,5 35 0,0 5 2 11,0-11,5 36 2,0 5 3 18,0-18,6 39 3,0 5 4 25,0-25,5 35 0,0 5 5 37,0-37,5 36 0,0 ggrraaddoo ddii ppeessoo ddii aannggoolloo ddiippoorroossiittàà ssaattuurraazziioonnee vvoolluummee aattttrriittoo ccooeessiioonneenn ((%%)) ss ((%%)) γγ ((kknn//mm33)) ϕϕ ((°°)) cc ((kkppaa)) a sabbie fini 49,81 0,47 14,71 35,00 0,0 limose b sabbie mediogrossolane incoerenti 47,87 0,78 15,62 36,38 4,2 c pomici eterometriche in matrice pozzolanica 59,25 0,93 15,54 36,50 6,0 d sabbie limose pozzolaniche 50,48 0,93 16,67 36,50 6,6 e sabbie grossolane ghiaiose 39,70 0,90 18,24 35,00 0,0 tab. 4 risultati delle prove di laboratorio per la determinazione delle proprietà meccaniche dei campioni mgf. mechanical properties of samples mgf as determined in laboratory. tab. 5 -medie aritmetiche dei risultati delle prove di laboratorio per la determinazione delle principali proprietà fisiche e meccaniche dei campioni mgf espresse in funzione delle unità litostratigrafiche riconosciute . arithmetic mean of main physical and mechanical properties of samples mgf plotted against lithostratigraphic units. uunniittàà lliittoossttrraattiiggrraaffiicchhee ne s e dei pesi di volume γ da porre probabilmente in relazione sia ad un lieve grado di cementazione dello scheletro vetroso, che può avere talora sensibilmente ridotto la porosità efficace dei sedimenti, che alla natura vulcanoclastica dei depositi. i pesi specifici reali sono stati determinati attraverso l’uso di picnometri collegati con pompa a vuoto. in molti casi, dati i valori bassi del grado di saturazione s, si è fatto riferimento alla porosità, invece che al peso di volume γ, per valutare lo stato di addensamento dei depositi. i risultati delle prove per la determinazione delle caratteristiche meccaniche, o di parametri ad esse correlabili, quali il numero di colpi n spt della standard penetration test, sono piuttosto disomogei, fatta eccezione per la coesione c la quale è risultata sempre piuttosto bassa, in tutte le unità campionate, nonostante un certa tendenza dei depositi piroclastici pozzolanici a presentare una debole cementazione in ambiente diagenetico marino. a tale proposito va ricordato che il minimo disturbo arrecato al sedimento durante le fasi di prelievo dei campioni danneggia le tessiture sedimentarie, distruggendo conseguentemente il tenue scheletro vetroso che conferisce, invece, una certa consistenza ai sedimenti in sito. a ciò, oltre che alla scarsa cernita ed alta variabilità granulometrica dei depositi vulcanoclastici, deve probabilmente imputarsi anche l’elevata dispersione delle misure di nspt che hanno evidenziato valori molto elevati o a rifiuto. le prove di taglio sono state effettuate con tre provini per ogni determinazione, imponendo pressioni verticali rispettivamente di 150 kpa, 300 kpa e 450 kpa. i risultati di queste prove hanno fornito valori dell’angolo di attrito ϕ normalmente proporzionali alle dimensioni medie dei granuli costituenti il sedimento. 6.2. analisi di facies e stratigrafia l’analisi delle associazioni di litofacies della successione in studio indica ambienti deposizionali di transizione (spiaggia sommersa, laguna costiera) di bassa energia, dove la circolazione ristretta e l’assenza di moto ondoso e forti correnti lungo costa favoriscono l’accumulo dei depositi con frazione fine relativamente abbondante. la successione stratigrafica investigata evidenzia un’evoluzione generale trasgressiva, localmente interrotta da due brevi fasi regressive probabilmente collegate ad un rapido accumulo (giacitura primaria) e/o trasporto (con parziale rimaneggiamento) di depositi piroclastici che terminano con la formazione di due livelli di torba, denominati rispettivamente t1 e t2 (fig. 3). in particolare, il rapido accumulo delle piroclastiti dell’unità c (insinga et al., 2001), che può raggiungere uno spessore di 5 m (sondaggio mgf 1), e la conseguente diminuzione dello spazio di accomodamento disponibile per i sedimenti, determinano il passaggio da condizioni di spiaggia sommersa (unità b) a condizioni tipiche di ambiente meno profondo (unità d). tale passaggio avviene attraverso una fase di transizione in cui predominano processi di alterazione tipici di ambiente vadoso e/o subaereo, testimoniati dalle frequenti tracce e patine di ossidazione che caratterizzano i primi metri dell’unità c. ulteriore evidenza a sostegno di episodi regressivi è data proprio dallo sviluppo dei livelli torbosi i quali suggeriscono brevi episodi di emersione con formazione di insenature o lagune costiere effimere che poi evolvono nuovamente ad ambienti di spiaggia sommersa. successioni di questo genere, con depositi di transizione o continentali intercalati a sedimenti marini, sono tipiche di zone costiere in aree vulcaniche attive (lajoie & stix, 1992). nel corso dei carotaggi sono stati campionati due livelli di torba, t1 e t2, rispettivamente nei sondaggi mgf 3 (profondità 9 m, unità d) e mgf 1 (profondità 31 m, al passaggio tra le unità a e b). i campioni di torba hanno fornito età radiometriche ( 14c) di 3560±40 anni e 7815±55 anni rispettivamente, e risultano pertanto correlabili con due paleosuoli che testimoniano a terra fasi di quiescenza dell’attività vulcanica dei campi flegrei. in particolare, l’orizzonte t2 si correla con il paleosuolo b (8,2-4,8 ka, di vito et al., 1999) o paleosuolo p3 (8,04,6 ka, rosi & sbrana, 1987), mentre l’orizzonte t1 è correlabile alla fase di quiescenza dell’attività vulcanica tra l’eruzione di senga (3,7 ka, ghiara, 1990) e quella di monte nuovo (1538 a.d., rosi & sbrana, 1987). nessuno dei carotaggi effettuati ha raggiunto il substrato tufaceo (ca 11000 anni) che pure si rinviene estesamente in affioramento nelle aree circostanti il porto di miseno. ciò suggerisce per l’area di studio elevati tassi di sedimentazione durante l’olocene superiore, da porsi probabilmente in relazione ai processi di subsidenza e di collasso vulcano-tettonico di aree discrete del settore occidentale dei campi flegrei, di cui la piattaforma interna del golfo di pozzuoli rappresenta il settore sommerso (colantoni, 1972; pescatore et al., 1984; milia, 1998). quest’osservazione, associata alle determinazioni delle età assolute dei livelli di torba t1 e t2, intercalati ai depositi di porto miseno, indica che la base della successione carotata ha un’età probabilmente compresa tra 9.000-10.000 anni. una stima dei tassi di sedimentazione medi, negli intervalli di tempo compresi all’incirca tra 8.000 e 3.600 anni e tra 3.600 anni e l’attuale, calcolati in base agli spessori stratigrafici delle unità inferiori (a e b) e superiori (d ed e) del sondaggio mgf 1, conduce a valori di 3.5 m/ka e di 2.2 m /ka, rispettivamente. se si ammette che i tassi di sedimentazione misurati rappresentino in qualche modo il riflesso della variabilità dei volumi di materiale vulcanoclastico disponibili per l’apporto sedimentario in ambiente costiero, si può avanzare l’ipotesi che il valore inferiore del tasso di sedimentazione registrato nella parte alta della successione (unità d ed e) sia conseguenza dello scarso apporto di sedimenti vulcanoclastici nell’area per l’assenza di manifestazioni eruttive durante gli ultimi 3.6 ka. la successione olocenica di porto miseno può essere tentativamente correlata con altri depositi marini tardo-quaternari già descritti in letteratura lungo la fascia costiera dei campi flegrei. in particolare, l’unità a, e le unità b-c e d-e, discusse in questo lavoro, ben si correlano rispettivamente con le unità sismostratigrafiche g1, g2 e g3, individuate nel settore centrale ed in quello orientale della piattaforma continentale del golfo di pozzuoli (milia, 1996; 1998; milia & torrente, 2000). una correlazione possibile con successioni affioranti a terra è individuabile, inoltre, nei depositi del terrazzo marino de “la starza” presso pozzuoli dove la successione olocenica è stata sollevata di circa 40 m al di sopra del livello del mare durante gli ultimi 4000 anni (cinque et al., 1985; barra, 1991). 77.. rriinnggrraazziiaammeennttii si ringraziano il corpo della guardia di finanza per l’assistenza ed il supporto logistico fornito durante le operazioni di carotaggio sul molo e nello specchio d’acqua antistante la stazione navale di porto miseno nel comune di bacoli (na) ed i dott. alessandro conforti e gennaro sarnacchiaro per l’attiva collaborazione offerta durante le operazioni di carotaggio e nella stesura delle singole stratigrafie. gli autori sono grati inoltre a tutti i ricercatori e tecnici dell’istituto di ricerca del cnr geomare sud di napoli che, a vario titolo, hanno reso possibile lo svolgimento di questo lavoro ed all’ing. armando simonelli che ha fornito utili consigli per un corretto inquadramento dell’analisi ed interpretazione dei dati geotecnici. si desidera ringraziare ancora il prof. aldo cinque ed un revisore anonimo per i preziosi suggerimenti e spunti forniti in sede di revisione critica del manoscritto. le analisi delle proprietà fisiche e meccaniche condotte su campioni indisturbati sono state eseguite dal laboratorio ufficiale “geologia tecnica” di salerno. le determinazioni delle età assolute con il metodo del radiocarbonio (14c) dei campioni di torba sono state effettuate presso il laboratorio “isotoptech” di debrecen, ungheria. 88.. llaavvoorrii cciittaattii aiello g., budillon f., cristofalo g., d’argenio b., de alteriis g., de lauro m., ferraro l., marsella e., pelosi n., sacchi m., tonielli r., (1999): marine geology and morphobathymetry in the bay of naples, conisma, spec.vol. on the int. cong. “diversità e cambiamenti”, ischia, october 1998, springer-verlag. aiello g., budillon f., d’argenio b., de alteriis g., de lauro m., ferraro l., insinga d., marsella e., molisso f., pelosi n., sacchi m., tonielli r. (2001): nuovi dati sulla morfologia sottomarina e sedimentazione recente nel golfo di napoli (tirreno meridionale), “geologia ambientale”, volume speciale, in stampa. alessio m., allegri l., antonioli f., belluomini g., improta s., manfra l., martinez m.p. (1994): la curva di risalita del mar tirreno negli ultimi 40 ka 20 insinga et al. ottenuta mediante datazioni di speleotemi sommersi e dati archeologici, memorie descrittive della carta geologica d’italia, lliiii, 261-275. barra d., (1991): studio del pleistocene superioreolocene delle aree vulcaniche campane, tesi di dottorato, università di napoli federico ii, 298 pp. barberi f., corrado g., innocenti f., luongo g., (1984): phlegrean field 1982-1984: brief chronicle of a volcano emergency in a densely populeted area, bull.volcanol., 4477--22, 175. caputo p., (1989): attività di tutela della soprintendenza archeologica di napoli e caserta, atti ii conv. naz. archeologia subacquea. ministero beni aa.cc., roma cinque a., rolandi g., zamparelli v., (1985): l’estensione dei depositi marini olocenici nei campi flegrei in relazione alla vulcano-tettonica, boll. soc. geol. ital., 110044, 327-348. cinque a., russo f., pagano m., (1991): la successione dei terreni di età post-romana delle terme di misero (napoli): nuovi dati per la storia e la stratigrafia del bradisisma puteolano, boll.soc.geol.it, 111100, 231-244. colantoni p., del monte m., fabbri a., gallignani p., selli r. & tomadin l. (1972) ricerche geologiche nel golfo di pozzuoli, in: versino, l. (ed.), relazione sui rilievi effettuati nell’area flegrea nel 1970-71, cnr, quaderni de “la ricerca scientifica”, 83, pp. 23-76. d’antonio m., civetta l., orsi g., pappalardo l., piochi m., carandente a., de vita s., di vito m.a., isaia r., (1999): the present state of the magmatic system of the campi flegrei caldera based on a reconstruction of its behavior in the past 12 ka, journal of volcanology and geothermal research, ((9911)) 22--44, 247-268 di girolamo p., ghiara m.r., lirer l., munno r., rolandi g. & stanzione d., (1984): vulcanologia e petrologia dei campi flegrei, boll. soc. geol. it., 110033, 349-413. di vito m., lirer l., mastrolorenzo g., rolandi g., (1987): the monte nuovo eruption (campi flegrei, italy), bull. volcanol. 4499, 608-615. di vito m., isaia r., orsi g., southon j., de vita s., d’antonio m., pappalardo l., piochi m., (1999): volcanism and deformation since 12,000 years at the campi flegrei caldera (italy), journal of volcanology and geothermal research, (9911)) 22--44, 221-246. dvorak j.j. & mastrolorenzo g. (1991): the mechanisms of recent vertical crustal movements in campi flegrei caldera, southern italy, special papergeological society of america. ghiara m.r., (1990): studio evolutivo del sistema magmatico flegreo negli ultimi 10 ka, boll. soc. natur. napoli, 9988--9999, pp 30. insinga d., lanphere m., morra v., sacchi m., molisso f., ricci g., (2001): stratigraphy, 14c and 40ar/39ar geochronology, and petrochemistry of holocene deposits in an active volcanic area: the pozzuoli bay, southern italy, eug assembly, strasbourg, april 2001. ippolito f., d’argenio b., pescatore t & scandone p., (1973a): unità stratigrafico-strutturali e schema tettonico dell’appennino meridionale, ist. geol. geofis. università napoli, pubbl. 15, 1-33. lajoie j. and stix j., (1992): volcaniclastic rocks. in: r. g. walzer and n. p. james (eds), facies models: response to sea level change. geological association of canada, pp. 101-118. milia a.,(1996): evoluzione tettono-stratigrafica di un bacino peritirrenico: il golfo di napoli, tesi di dottorato, università degli studi di napoli federico ii. milia a., (1998): stratigrafia, strutture deformative e considerazioni sull’origine delle unità deposizionali oloceniche del golfo di pozzuoli (napoli), boll. soc. geol. it., 117, 777-787. milia a., (2000): active deformation and volcanism offshore campi flegrei, italy: new data from highresolution seismic reflection profiles, marine geology, 171, pp.61-73. milia a., torrente m.m., (2000): fold uplift and synkinematic stratal architectures in a region of active transtensional tectonics and volcanism, eastern tyrrhenian sea, gsa bulletin, 112, p 1531-1542. orsi g., de vita s., di vito m., (1996): the restless resurgent campi flegrei nested caldera (italy): constraints on its evolution and configuration, journal of vulcanology and geothermal research, 7744, 179-214. ortolani f., aprile f., (1978): nuovi dati sulla struttura profonda della piana campana a sud-est del fiume volturno, boll. soc. geol. it., 9988, 591-608. pescatore t.s., diplomatico g., senatore m.r., tramutoli m., & mirabile l., (1984): contributi allo studio del golfo di pozzuoli: aspetti stratigrafici e strutturali, mem. soc. geol. it., 2277, 133-149. pirazzoli p.a. (1976): sea-level variations in the northwest mediterranean during roman times, science, 119944, 519-521. rosi m. & sbrana a., (1987): phlegrean fields, c.n.r., quaderni de “la ricerca scientifica”, 111144--99, pp176. 21 ms. ricevuto il 15 maggio 2001 testo definitivo ricevuto il 23 aprile 2002 ms. received: may 15, 2001 final text received: april 23, 2002 stratigrafia e caratteristiche fisiche... microsoft word 11_pini_lm03.doc available online http:/amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 26 (1), 2013, vii-ix report on the icdp workshop dove “drilling overdeepened alpine valleys” (como and valtellina, 3-5 april 2013) roberta pini cnr istituto per la dinamica dei processi ambientali, laboratorio di palinologia e paleoecologia, milano, italy corresponding author : roberta pini <roberta.pini@idpa.cnr.it> http://palinologia.disat.unimib.it abstract: here i provide a short report on the icdp-funded workshop dove (drilling overdeepened alpine valleys), held in como and valtellina between 3-5 april 2013. discussion, led by the project principal investigators, aimed at defining the scientifical issues and the financial budget of a multinational drilling initiative in and across the alps. keywords: icdp, dove, overdeepened alpine valleys. on 3-4 april 2013 the icdp workshop dove "drilling overdeepened alpine valleys" was held in the scenic villa del grumello, on the south-western shore of lake como (northern italy). icdp is the acronym for the international continental scientific drilling program; it is a transnational program based at the gfz german research centre for geosciences, aiming at promoting, funding and coordinating continental scientific drillings with relevant scientific objectives of global significance (fig. 1). icdp supports researches focused on climate dynamics and global environment, life history, natural resources and a wide range of geologically-relevant topics like active faults and earthquakes, volcanoes, hot spots, plate collision and impact structures. project proposals may be submitted to icdp once a year by scientists from member and non-member countries looking for logistical and financial support to continental drillings. the dove workshop (fig. 2), funded by icdp, fig. 1 drilling operations at lake ohrid (macedonia, albania) in the framework of the icdp-funded project scopsco "scientific collaboration on past speciation conditions in ohrid" (photo www.icdp-online.org). pini r. viii joined experts in drilling and core-logging techniques, geochronology, geophysics, glacier modelling, natural hazards and nuclear waste, sedimentology, stratigraphy and structural geology to define the scientific and economic agenda of a multinational drilling initiative across the alpine chain. the dove project aims at exploring nature, geometry and age of sedimentary successions filling overdeepened alpine valleys, to answer to key questions related to rates and processes shaping alpine landscapes and their forelands. special attention will be paid to the effects of multiple glaciations on mountain areas, to reconstruct their timing and extent and decipher regional differences, and to the history of biodiversity and the impact of glaciations on original ecosystems of the alps. the potential of the study areas for ground-water and geothermal resources and as nuclear waste and gas disposal sites will be carefully evaluated. the meeting, organized by cnr idpa milano, was attended by 46 professors, researchers, phd students and professionals representing 9 european nations (austria, denmark, germany, france, italy, slovenia, sweden, switzerland, the netherlands) and usa (fig. 3). the workshop opened with a note by dr. ulrich harms, icdp executive secretary, describing icdp organization, activities, funding strategies and criteria for project selection and evaluation. criteria applied for evaluation are the project's global significance, the pooling of resources and technologies by a broad scientific international team, the societal relevance of the problem, the necessity for drilling and the balance of costs and drilling design. the workshop scientific activity developed through two days of plenary sessions and working groups discussions focusing on pre-site surveys, methods, goals, active and future collaborations and potential drilling sites in austria, germany, italy, slovenia, switzerland. drilling techniques will be carefully evaluated, given the expected core lenghts (up to several hundred meters, from the ground level possibly down to bedrock) and the need to have sufficient amounts of sediment for several destructive analysis (and therefore smaller core diameters should be avoided). on april 5 workshop participants were involved in a one-day fieldtrip to a potential drilling site in the nearby overdeepened valtellina area. despite adverse weather conditions preventing any clear view from the panoramic point towards the valley floor, participants were offered a comprehensive sketch on geological investigations carried out in recent years in this area by regione lombardia and cnr-idpa, consisting of two long cores (teglio and sondalo) drilled in the frame of the new geological map of lombardy and seismic profiles. the excursion ended with the visit to the local drilling company storing the 208 mlong teglio core observing, describing and discussing sediment features and their meaning. the workshop participants agreed to endorse the effort of submitting a full proposal for the dove project to icdp by january 2014. a group of principal investigators, namely prof. flavio anselmetti (univ. of bern), dr. milos bavec (geological survey of slovenia), dr. gerald gabriel (leibnitz institute for applied geophysics in hannover), prof. frank preusser (univ. of stockholm), dr. cesare ravazzi (consiglio nazionale delle ricerche milano) and dr. jürgen reitner (geological survey of austria), will be in charge of it. the success of fig. 2 the logo of the icdp dove project (design by c. ravazzi, cnr-idpa milano). icdp dove workshop ix the project relies on the interest and support by research agencies, universities, local and regional administrations, industry groups. indeed, in case of positive evaluation, icdp funds will be granted for project and drilling development, while applicants are asked to raise additional resources to fully cover drilling costs, facilities, scientific data production and management. more informations on icdp and its activity can be found at www.icdp-online.org. those interested in joining the dove adventure, promoting deep drillings and sharing their social and scientific outcomes, can contact dr. cesare ravazzi at cnr idpa (cesare.ravazzi@idpa.cnr.it). ms. received: may 10, 2013 final text received: may 14, 2013 fig. 3 group photo of the participants to the icdp dove workshop (photo courtesy markus fiebig). << /ascii85encodepages false /allowtransparency false 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documenti pdf creati possono essere aperti con acrobat e adobe reader 5.0 e versioni successive.) /enu (use these settings to create adobe pdf documents suitable for reliable viewing and printing of business documents. created pdf documents can be opened with acrobat and adobe reader 5.0 and later.) >> >> setdistillerparams << /hwresolution [1200 1200] /pagesize [396.850 566.929] >> setpagedevice imp.giraudi evoluzione tardo-olocenica del delta del tevere carlo giraudi enea c.r. casaccia, c.p. 2400, 00100 roma a.d. riassunto: c. giraudi, evoluzione tardo-olocenica de delta del tenere. it issn 0394-3356, 2004 il delta del tevere è stato studiato dal punto di vista morfologico con l’uso di fotografie aeree di tre diversi voli e con indagini di campagna nell’area dell’antico stagno di maccarese. l’esame morfologico ha permesso di stabilire che vi sono gruppi di cordoni litorali che costituiscono otto insiemi omogenei: questi possono essere seguiti sia nella zona settentrionale che meridionale del delta. la datazione dei cordoni litorali è stata ottenuta sia grazie alla presenza di costruzioni e manufatti antichi sui cordoni stessi, sia attraverso la datazione dei sedimenti presenti nelle depressioni alle spalle dei cordoni litorali. i gruppi di cordoni litorali affioranti al piano campagna indicano otto fasi di avanzamento del delta: la prima fase è più antica di circa 3700-4000 anni a.c.; la seconda più antica di 32752930 anni a.c.; la terza ha età prossima a 3275-2930 anni a.c.; la quarta ha età compresa tra 2140-1920 a.c. e 1300-1000 a.c.; la quinta ha età prossima a 910-800 anni a.c.; la sesta ha un’età compresa tra il iv secolo a.c. ed il x secolo d.c.; la settima e l’ottava fase sono databili al periodo compreso tra il xv ed il xix secolo. l’esame dell’andamento dei cordoni litorali ha permesso di stabilire che almeno fino al ix secolo a.c. la foce del tevere era situata in corrispondenza dell’attuale alveo di fiumicino: solo tra viii e iv secolo a.c. il fiume subì una diversione verso l’attuale foce. il delta ha subito anche varie fasi di arretramento, avvenute negli intervalli tra la sedimentazione dei cordoni litorali della prima e della seconda fase (età maggiore di 3275-2930 a.c.), tra quinta e sesta fase (età compresa tra viii e i secolo a.c.), nel corso della sesta fase (iii secolo d.c.), e l’ultima, quella morfologicamente più evidente, successiva ai cordoni della sesta fase, databile al medioevo (x-xiii secolo). sensibili arretramenti della linea di costa, devono essere avvenuti anche tra 6000 e 2000 anni fa a causa della risalita eustatica del livello del mare: porzioni, anche estese, dei gruppi di cordoni litorali debbono quindi essere state erose o giacere coperte da sedimenti più recenti. i cordoni litorali formati nel corso della forte avanzata del delta che avvenne a partire dal xv secolo occupano un’estensione maggiore di quella di tutti i cordoni di età più antica. questo fatto non implica che il loro sviluppo sia eccezionale: i cordoni litorali più recenti potrebbero essere più estesi solo perché conservati nella loro interezza. e’ stato rilevato che nell’area ad est di focene i cordoni litorali hanno subito vari sfondamenti nel corso del tempo: il primo dopo 3275-2930 anni a.c., il secondo in un periodo successivo a 910-800 anni a.c. e precedente al vii secolo a.c., il terzo nel corso, probabilmente, del i secolo d.c. in particolare, il secondo sfondamento ha permesso l’ingressione di acqua salata nelle paludi di acqua dolce dello stagno di maccarese che esistevano almeno dal 5300-5200 a.c. nell’area di vignole, sono stati poi individuate tracce di alvei originatisi per la rottura degli argini naturali del tevere e ventagli di crevassa, che possono essere datati attorno al ix e x secolo a.c. nell’area di maccarese e di le pagliete sono stati individuati i resti di due canali artificiali di età romana che suggeriscono, insieme ai manufatti presenti a campo salino, un tentativo di gestione complessiva delle paludi presenti nell’area settentrionale del delta. dal confronto tra l’evoluzione del delta, la frequenza degli eventi alluvionali del tevere a roma, le fasi climatiche registrate in appennino (dedotte dalle variazioni del ghiacciaio del calderone, dei laghi fucino e trasimeno, e dallo studio delle alluvioni oloceniche di campo imperatore) è emerso chiaramente che le fasi di progradazione del delta sono coeve con fasi climatiche più fredde (avanzate del ghiacciaio del calderone) e umide (aumento di livello dei laghi), mentre le fasi di arretramento della costa sono correlabili a periodi più caldi caratterizzati da sviluppo dei suoli in alta montagna e ritiro del ghiacciaio del calderone. l’evoluzione del delta, seppure condizionato da interventi antropici, appare essenzialmente influenzata dall’evoluzione climatico-ambientale dell’appennino. infine è stato ipotizzato che l’asimmetrico sviluppo dei cordoni litorali a nord e a sud dell’area dei porti imperiali sia dovuto ad un diverso grado di subsidenza. anche se limitata, nel corso del tempo la subsidenza avrebbe influenzato l’evoluzione della linea di costa: si sarebbe formata una discontinuità nei cordoni litorali nell’area a nord del ramo di fiumicino, favorendo la formazione di un piccolo golfo, nelle adiacenze del quale vennero scavati i bacini e costruite le infrastrutture del porto di claudio. abstract: c. giraudi, late holocene evolution of the tiber delta it issn 0394-3356, 2004 the tiber delta has been studied using aerial photographs taken in three different flights in order to recognize geomorphological features, and with field surveys in the area of the ancient stagno di maccarese marshes.morphological studies have shown that there are groups of beach ridges forming eight homogeneous complexes that can be followed both in the northern and in the southern part of the delta. dating of these beach ridges has proved possible thanks to the presence of buildings and artefacts on the ridges and through dating of the sediments in the depressions behind the ridges. the groups of outcropping beach ridges indicate eight phases of delta advance: the first phase is older than 3700-4000 years bc; the second one is older than 3275-2930 years bc; the third one is dated about 3275-2930 years bc; the age of the fourth one is between 2140-1920 bc and 1300-1000 years bc; the fifth one is dated about 910-800 years bc; the age of sixth one is between the 4th century bc and the 10th century ad; and the seventh and eighth phases are dated between the 15th and the 19th century ad. examination of the beach ridges has established that at least until the 9th century bc the mouth of the tiber was situated where the present fiumicino channel runs. it was only between the 8th and the 4th century bc that the river became diverted to its present bed. the delta has also undergone various retreat phases, which occurred between the sedimentation of the beach ridges of the first and second phase (age greater than 3275-2930 years bc), between the fifth and the sixth phase (age between 8th and 1st century bc), during the sixth phase (3rd century ad), and the morphologically most evident one, after the sixth phase ridges, dated from the middle ages (10th-13th century). appreciable retreat of the coastline must also have taken place between 6000 and 2000 years ago due to the eustatic rise in sea level, and parts – even extensive ones – of the groups of beach ridges must therefore have been eroded or overlain by more recent sediments. the beach ridges formed during the significant advance of the delta that took place as from the 15th century occupy an area perhaps even greater than that of all the earlier ridges. this fact does not imply that their development is exceptional: the most recent beach ridges might be more extensive only because they have been entirely preserved. it has been observed that in the area to the east of focene the beach ridges have been broken up a number of times: the first time after 3275-2930 years bc, the second time in a period after 910-800 years bc and before 7th century bc, and the third time probably during the 1st century ad. in particular, the second break-up enabled salt water to flow into the stagno di maccarese freshwater maril quaternario italian journal of quaternary sciences 17(2/2), 2004, 477-492 478 c. giraudi 1 introduzione e metodo di studio l’area deltizia del tevere, attualmente fortemente antropizzata per la presenza di centri abitati e quartieri di roma, vie di comunicazioni, l’aeroporto di fiumicino, ecc., presentava un aspetto ancora molto diverso nel corso del xix secolo e dell’inizio del xx secolo. sia a nord che a sud dell’alveo fluviale si estendevano grandi aree palustri, circondate da pascoli, che venivano parzialmente sommersi durante il periodo invernale, e da boschi, secondo quanto rappresentato sulle carte di amenduni (1884). la zona venne poi bonificata con interventi che durarono dal 1889 fino agli anni ’30 del xx secolo, colonizzata e sottoposta a coltivazione intensiva. l’evoluzione del delta è stata oggetto di vari studi, a partire dalla seconda metà del xix secolo (oberholtzer, 1875; bocci, 1892). la maggior parte dei lavori moderni riguarda principalmente lo studio sedimentologico dei depositi tardo pleistocenici ed olocenici che formano il delta, messi in evidenza da molti sondaggi effettuati specialmente all’interno del perimetro dell’aeroporto internazionale leonardo da vinci di fiumicino (dragone et al., 1967; belluomini et al. 1986; bellotti et al., 1987; bellotti et al. 1989,1994, 1995; chiocci & milli, 1995; amorosi & milli, 2001). in vari lavori sono state presentate ricostruzioni areali dell’evoluzione del delta nel corso del tempo basate sui dati geologici e su informazioni storiche, ed avanzate ipotesi sulla posizione delle linee di riva in varie epoche, a partire dal periodo romano (belluomini et al. 1986; bellotti et al., 1987; bellotti et al. 1989,1994,1995). il metodo utilizzato nel presente lavoro è stato sia geomorfologico che stratigrafico. sono state rilevate da foto aeree le caratteristiche e la distribuzione dei cordoni litorali su tutta l’area del delta in modo da evidenziarne l’evoluzione e verificare gli spostamenti di alveo del tevere avvenuti nel corso del tempo. l’area è stata studiata utilizzando fotografie scattate da aerostato nel 1911, immagini aeree della raf del 1943 e fotogrammi del volo base italiano del 1954. i dati emersi dalle indagini fotogeologiche sono stati riportati su carte di base a scala 1:25.000: queste permettono di valutare con buon dettaglio l’andamento dei cordoni litorali e le morfologie relative agli spostamenti nella foce del tevere. poichè l’area studiata è piuttosto estesa, nel presente lavoro gli elementi morfologici sono stati riportati a scale molto più piccole in due figure (fig. 1 e 2) di diverso dettaglio. oltre alle indagini fotogeologiche sono state condotte indagini stratigrafiche sui sedimenti di due aree, un tempo occupate dalle paludi dello stagno di maccarese, ubicate alle spalle dei cordoni litorali nelle zone di maccarese e di campo salino. tali indagini hanno permesso di ottenere elementi di datazione di varie fasi evolutive dello stagno. l’evoluzione delle paludi, come si vedrà oltre, è stata condizionata dallo sviluppo dei cordoni litorali e quindi dalle fasi di costruzione del delta. si è inoltre fatto ricorso a dati storici e a fonti latine, riportati in bibliografia, che si sono rivelati utili per le informazioni relative alle caratteristiche del delta, agli interventi sull’alveo ed al regime idraulico del tevere. la datazione di insediamenti, manufatti e opere permette anche di trarre utili indicazioni sull’estensione del delta nei tempi antichi. nel presente lavoro è stata quasi completamente trascurata la parte relativa all’evoluzione del delta negli ultimi 600 anni, in quanto l’argomento è già stato affrontato ed approfondito da innumerevoli lavori che, a partire da oberholtzer (1875) e bocci (1892), hanno datato le fasi di progradazione del delta utilizzando le date di costruzione di varie torri di difesa costruite nei pressi della foce del tevere in avanzamento. 2 morfologia e stratigrafia tardo-olocenica del delta il fiume tevere nell’area del delta risulta formato da due rami: il ramo principale, detto fiumara grande, sbocca nel mare a nw del lido di ostia, mentre il ramo secondario, più settentrionale, sbocca in mare presso fiumicino. secondo fonti latine (riportate in bellotti et al. 1994) il ramo di fiumicino, sarebbe stato scavato artificialmente nel ii secolo d.c., in corrispondenza della costruzione del porto di traiano. attualmente il delta del tevere ha un aspetto piuttosto simmetrico, con una evidente cuspide principale in corrispondenza dello sbocco in mare del ramo principale ed una cuspide assai meno pronunciata in corrishes, which have existed at least since 5200-5300 bc. in the vignole area, traces of channels produced by the breaking of the natural banks of the tiber have been found, as well as series of crevasses, which may be dated at around the 9th and 10th century bc. in the maccarese and le pagliete area, the remains of two artificial canals of roman age have been identified, suggesting, together with artefacts found at campo salino, an attempt at the overall management of the lagoon in the northern area of the delta. comparing the evolution of the delta, the frequency of flood events in the tiber at rome, and the climatic phases recorded in the apennines (deduced from the variations in the calderone glacier, in lakes fucino and trasimeno level oscillations, and from the study of holocene alluvial deposits at campo imperatore), it has emerged clearly that the delta progradation phases are coaeval with the cooler (advances of the calderone glacier) and wetter (increase in level of the lakes) climatic phases, while the phases of coastal retreat can be correlated with warmer periods characterized by the development of high mountain soils and the retreat of the calderone glacier. the evolution of the delta, although affected by anthropic measures, appears to have been essentially conditioned by the climatic-environmental evolution of the apennines. lastly, the hypothesis has been made that the asymmetric development of the beach ridges to the north and south of the area of the claudius and trajan ports was due to a different degree of subsidence. however limited, in the course of time this subsidence has influenced the evolution of the coastline: it probably favoured the formation of a discontinuity of the beach ridges in the area north of the fiumicino branch, helping to form a small inlet in which the port of claudius was constructed. parole chiave: olocene, delta del tevere, cordoni litorali, variazioni linea di costa, clima. keywords: holocene, delta of the river tiber, beach ridges, coastline variations, climate. 479evoluzione tardo olocenica ... fig. 1 il delta del tevere: elementi morfologici ed estensione dei cordoni litorali delle otto fasi the tiber delta: morphological features and extent of the beach ridges spondenza dello sbocco del ramo di fiumicino (fig. 1). come evidenziato da bellotti et al. (1995), morfologicamente il delta presenta una piana deltizia inferiore, costituita prevalentemente da cordoni litorali, mentre nella piana deltizia superiore, alle spalle dei cordoni litorali, sono presenti aree depresse che, prima della bonifica, erano occupate da paludi. nel tratto in cui attraversa la piana deltizia interna, il tevere scorre al centro di una larga fascia di alluvioni; esso separa così le aree depresse in una zona setten480 trionale, che un tempo ospitava lo stagno di maccarese, ed una meridionale, che ospitava lo stagno di ostia. altri stagni minori erano presenti nella zona dei porti imperiali e tra i cordoni litorali. le due paludi più estese furono collegate al mare da emissari artificiali, scavati nel corso di tentativi di bonifica precedenti a quello moderno: tali canali sfociano in mare presso focene, a nord di fiumicino e nella zona del lido di ostia. nella parte settentrionale del delta è presente la foce del fiume arrone, che interrompe i cordoni litorali e separava, nel passato, le paludi de le pagliete dalla palude di maccarese. l’andamento dei cordoni litorali, esaminato e cartografato in dettaglio, ha permesso di distinguere vari insiemi di cordoni litorali: ogni insieme può essere considerato come parte di una stessa fase di progradazione del delta. i cordoni litorali di una stessa fase presentano caratteri morfologici comuni: direzione, continuità laterale, elevazione delle dune, grado di conservazione, ecc.; in prossimità della foce del fiume sovente risultano separati dai precedenti e dai successivi per la presenza di fasce depresse strette ed allungate impostate su sedimenti di spiaggia, palustri o alluvionali. di particolare interesse è stata poi la constatazione che i cordoni litorali di alcune fasi tagliano quelli di fasi precedenti: tale situazione morfologica dimostra l’esistenza di periodi di arretramento della linea di costa. sia il dettaglio nel ricostruire l’andamento dei cordoni litorali, sia l’esame di fotografie aeree relative a diversi periodi, sia l’uso di dati stratigrafici per la datazione dei cordoni litorali hanno permesso di ottenere un quadro molto più complesso dell’evoluzione tardo-olocenica del delta rispetto a quanto ipotizzato fino ad ora. 2.1 i cordoni litorali e la loro datazione la geometria dei cordoni litorali è già stata parzialmente evidenziata da dragone et al. (1967) sul foglio geologico a scala 1:100.000 cerveteri della carta geologica d’italia. in bellotti et al., (1994) l’andamento dei cordoni litorali è stato rappresentato schematicamente a scala molto piccola. nel corso del presente lavoro sono stati distinti otto gruppi di cordoni litorali: i più interni sono, evidentemente, i più antichi. in fig. 1 sono cartografati i vari gruppi omogenei di cordoni litorali, ma la loro rappresentazione cartografica è semplificata per problemi di scala. una rappresentazione più dettagliata della porzione centrale del delta è riportata in fig. 2. la prima fase di formazione di cordoni litorali è testimoniata da due fasce di dune poco estese presenti sia a nord che a sud del tevere. la seconda fase è rappresentata da un gruppo di cordoni abbastanza esteso, presente sia a nord che a sud del tevere. i cordoni scompaiono avvicinandosi al fiume in quanto risultano coperti da sedimenti alluvionali o erosi. un lembo di questo gruppo di cordoni è stato individuato nella zona dove il ramo di fiumicino si distacca dall’alveo principale ed appare situato sulla prosecuzione verso nw dei cordoni meridionali. osservando l’andamento quasi rettilineo dei cordoni litorali di questa fase a nord e a sud del tevere è possibile notare che essi non risultano allineati e che i cordoni meridionali sono più avanzati verso il mare. non si rilevano indizi di una cuspide, ma lo sbocco in mare del tevere deve essere stato in corrispondenza o poco a nord dei porti di claudio e di traiano. non si hanno elementi di datazione diretta di tali cordoni. i cordoni litorali della terza fase sono rappresentati estesamente a nord e a sud del tevere, anche se sono parzialmente erosi e coperti da sedimenti alluvionali più recenti. anche in questo caso l’andamento dei cordoni litorali è rettilineo, ma i cordoni posti a nord e a sud del fiume non risultano allineati e quelli meridionali sono più avanzati verso il mare. non sono state rilevate tracce di cordoni indicanti una cuspide, tuttavia la evidente discontinuità tra i cordoni indica che la foce del tevere doveva essere situata nella zona dei porti imperiali. non si hanno elementi di datazione diretta di questi cordoni. i cordoni litorali della quarta fase sono estesi a nord e a sud del tevere, ma conservano una cuspide evidente ai margini del ramo di fiumicino, nei pressi dei porti imperiali. lo sbocco in mare del tevere doveva avvenire in questa zona. la porzione meridionale della cuspide non presenta però continuità col ramo settentrionale dei cordoni litorali di questa fase ed appare più avanzata verso mare. i cordoni di questa fase possono essere datati ad un periodo precedente l’età del bronzo recente (circa xiii-xi secolo a.c.): manufatti di tale età sono stati infatti rinvenuti negli scavi delle terme di nettuno nella città romana di ostia (zevi, 1968, in conti, 1982), che giace su tali sedimenti. i cordoni litorali della quinta fase sono assai meno estesi sia a nord che a sud del tevere, per il resto mostrano un andamento del tutto simile a quelli della quarta fase: si riconosce una cuspide nella zona del ramo di fiumicino presso i porti imperiali; non c’è continuità tra la porzione settentrionale della cuspide e il ramo settentrionale dei cordoni della stessa fase poiché la cuspide appare più avanzata verso mare. sui cordoni litorali di questa fase sono fondati i resti del faro romano sui quali è costruita la torre boacciana, immediatamente ad ovest della città romana di ostia. un molo del porto di claudio, databile verso la metà del i secolo d.c. è ancorato ai cordoni litorali della quinta fase e appena a nord del porto, i cordoni di questa fase sono tagliati da un canale, ora colmato, collegato alle opere eseguite al contorno del porto di claudio (testaguzza, 1970). inoltre tali cordoni litorali debbono essere datati ad un periodo precedente il iv secolo a.c. in base alle considerazioni riportate di seguito. il tevere subì una diversione verso sud dopo la fine della quinta fase, e la sua foce migrò nella zona di ostia antica (vedasi oltre). poiché secondo le fonti storiche la città romana di ostia venne fondata alla foce del tevere all’inizio del iv secolo a.c., la diversione del tevere dalla zona dei porti imperiali verso sud deve essere avvenuta prima del iv secolo. ne consegue che i cordoni litorali della quinta fase debbono essere più antichi del iv secolo a.c. i cordoni della sesta fase sono poco estesi a sud del tevere, occupano una fascia molto stretta nella zona dei porti imperiali, ma si espandono molto a nord. l’andamento dei cordoni mostra caratteristiche assai diverse da quelli precedenti: vi è una cuspide ben c. giraudi 481evoluzione tardo olocenica ... fig. 2 – geologia della porzione centrale del delta del f. tevere. legenda:i. ii. iii. iv. v. vi. vii, viii = cordoni litorali dalla prima alla ottava fase; sp= sedimenti prevalentemente palustri; sa= sedimenti prevalentemente alluvionali; asp= sedimenti alluvionali o di spiaggia o palustri, delle aree comprese tra cordoni litorali di diverse fasi; p= paleoalvei del tevere; t.lgm= depressione della valle del tevere durante l'ultimo massimo glaciale; rav= alvei e ventagli di crevassa di le vignole; rpc= depositi di riempimento del porto di claudio; a= aree antropizzate in antico (città, porti, accumuli antropici di sabbia. le linee isopache si riferiscono allo spessore dei sedimenti deltizi posteriori all'ultimo massimo glaciale (ridisegnato dalla fig. 3 di bellotti et al. 1995). i quadrati neri indicano le torri costiere e la data di costruzione. geology of the central portion of the tiber delta. legend: i. ii. iii. iv. v. vi. vii, viii = beach ridges from the first to the eighth phase; sp= mainly marshy sediments; sa= mainly alluvial sediments; asp= alluvial or beach or marshy sediments, in the areas between beach ridges of various phases; p= ancient stream bed of the tiber; t.lgm= tiber valley depression during the last glacial maximum; rav= stream beds and crevasse splays of le vignole; rpc= deposits in the claudius harbor; a= areas of human settlement in roman times (towns, ports, buildings anthropic sand accumulations). the isopach lines refer to the thickness of the delta sediments after the last glacial maximum (redrawn from the fig. 3 by bellotti et al. 1995). the black squares mark the coastal towers and their age. 482 riconoscibile in corrispondenza del ramo principale del tevere, poco a ovest di ostia antica. nella zona dei porti imperiali i cordoni litorali della sesta fase tagliano quelli precedenti e, anche se conservano una forma cuspidata, la loro morfologia sembra causata da un adattamento alla forma dei cordoni più antichi. a differenza di quelli delle fasi precedenti e successive, l’estensione dei cordoni litorali varia moltissimo: sono poco estesi e formano una fascia ristretta a sud della foce del tevere, ma sono molto allungati e danno luogo ad una fascia molto più larga verso nord. secondo plinio il vecchio (in bellotti et al. 1994), il delta avrebbe formato una cuspide solo nel corso del i secolo a.c.; virgilio e plutarco segnalano, rispettivamente, l’abbondanza del trasporto di sabbia alla foce del tevere ed il parziale insabbiamento della foce nel i secolo a.c. osservando la zona appena a nord dei porti imperiali (fig. 2) è possibile rilevare che i più antichi cordoni di questa fase sono tagliati dalla porzione terminale di un canale, ora colmato, che secondo testaguzza (1970) sarebbe collegato alle opere eseguite al contorno del porto di claudio; il canale è databile alla metà del i secolo d.c. la porzione più antica dei cordoni litorali della vi fase deve quindi essersi sviluppata a partire da un momento successivo al iv secolo a.c. (dal i sec. a.c. secondo plinio il vecchio) ed essere precedente ai lavori del porto di claudio, databili verso la metà del i sec d.c. una parte dei cordoni litorali di questa fase appoggia sul lato esterno di un molo del porto di claudio, ma appare tagliata da una depressione lunga e stretta (apparentemente un canale che metteva in comunicazione il bacino del porto di claudio con il mare). i cordoni della porzione intermedia della sesta fase chiudono invece la suddetta depressione: secondo testaguzza (1970), che interpreta alcuni dati archeologici, la chiusura del canale che usciva dal porto di claudio sarebbe avvenuta nel vi secolo d.c. secondo bellotti et al. (1994), autori romani segnalano che nel corso del iii secolo dovettero essere eseguite opere di protezione della via severiana (che correva a sudest di ostia antica, nella parte meridionale del delta) danneggiata dalle onde; questo implica che la formazione dei cordoni della sesta fase non è stata continua, ma interrotta almeno da un periodo di regressione della linea di costa. i cordoni della settima fase sono presenti solamente nella zona centrale del delta. la loro forma indica, in grande, una cuspide in corrispondenza dell’alveo principale, ma al centro di tale cuspide i cordoni rientrano verso terra, tagliando quelli della fase precedente. anche nella zona dei porti imperiali tali cordoni tagliano i precedenti. i cordoni litorali della sesta fase debbono quindi essere stati erosi a seguito di un forte arretramento della linea di costa avvenuto prima dell’inizio della sedimentazione dei cordoni litorali della settima fase. i cordoni litorali di questa fase testimoniano un avanzamento della linea di riva rispetto alla posizione di torre boacciana, che all’inizio del xv secolo giaceva ancora in prossimità della riva del mare (belluomini et al . 1986; bellotti et al ., 1987,1989,1994,1995). sui cordoni litorali della stessa fase è costruito il forte di paolo iv databile al 1557. i cordoni litorali della settima fase possono quindi essere datati ad un periodo compreso tra il xv secolo e la prima metà del xvi secolo. i cordoni che indicano l’ottava ed ultima fase di avanzamento del delta costituiscono un insieme, molto esteso arealmente e complesso, nel quale potrebbero essere distinte varie sub-fasi, trascurate nel presente lavoro, ma evidenziate da limiti in fig. 2. nel corso di questa fase il delta avanzò molto velocemente dando luogo ad una morfologia fortemente cuspidata nella zona dell’alveo principale. in corrispondenza dell’alveo di fiumicino non vi sono indizi di cuspidi se non relativamente ai cordoni litorali più recenti. l’età di questa fase è successiva ai primi decenni del xvi secolo e le varie avanzate, ben documentate dagli autori precedenti, sono scandite (oberholtzer,1875; bocci,1892; belluomini et al. 1986; bellotti et al., 1987,1989,1994,1995) dalla costruzione di nuove torri di guardia sulle spiagge del delta in avanzamento. alla fine del xix secolo iniziò una fase di arretramento, diventata ancora più evidente verso la metà del xx secolo (bellotti, et al. 1994), che è stata contrastata con opere di difesa costiera. altri arretramenti della linea di costa erano già avvenuti nei periodi compresi tra la formazione dei cordoni della quinta e della sesta fase e tra quelli della sesta e della settima fase. per datare i più antichi cordoni litorali, non databili direttamente, è possibile ricorrere a dati stratigrafici raccolti nell’ambito delle paludi bonificate. nei pressi del sito eneolitico de le cerquete, a maccarese (fig. 1), nell’area settentrionale del delta, giraudi (2002a) ha individuato limi torbosi, posti al tetto di uno strato di torba, datati 4510±70 anni bp col metodo del 14c (data calibrata 3375-2930 a.c.) e sedimenti limosi palustri posti sopra il livello del mare (giraudi, 2002a), che sigillano il sito eneolitico attorno a 4375±55 anni b.p. (data calibrata 3140-2900 a.c., carboni et al., 2002). in quel periodo dovevano quindi essere presenti cordoni litorali, che raggiungevano quote superiori al livello del mare, in grado di impedire il deflusso dell’acqua dalle paludi. i cordoni che possono corrispondere ai sedimenti databili 3140-2900 cal. a.c. sono quelli prossimi al sito, cioè quelli della terza fase. nel lavoro di belluomini et al. (1986) sulla stratigrafia dei sedimenti che formano il delta del tevere nella zona dell’aeroporto di fiumicino, vengono riportate le datazioni di vari campioni prelevati da un livello di torba e limi torbosi presente esclusivamente alle spalle dei cordoni litorali riconoscibili in superficie; tali sedimenti hanno fornito età prossime a quelle relative al sito eneolitico di maccarese: le date ottenute sono comprese tra 5140±60 (data calibrata 4042-3792 a.c.) e 4630±60 (data calibrata 3626-3122 a.c.). la presenza di sedimenti di acqua dolce, prevalentemente organici, senza sensibili apporti terrigeni, implica che prima del 4042-3792 cal a.c. le paludi dovevano essere isolate anche dal tevere ed alimentate solo dai corsi d’acqua provenienti dalla zona collinare e dal f. arrone. i più antichi cordoni litorali affioranti in superficie sarebbero databili, quindi, a 4042-3792 cal a.c. o ad un periodo più antico. del resto gli studi geologici effettuati sul sito eneolitico delle cerquete di maccarese (giraudi, 2002a) avevano già dimostrato che le oscillazioni di livello dello stagno di maccarese, dal periodo neolitico alla media età del bronzo (quindi contemporaneamente c. giraudi e successivamente alla sedimentazione delle torbe), non erano collegati alle oscillazioni di livello del mare, ma erano ben correlabili con le oscillazioni di numerosi laghi presenti in italia centrale: doveva quindi mancare un collegamento tra lo stagno ed il mare. al di sotto delle torbe, nella zona di campo salino (vedasi oltre) sono presenti sedimenti contenenti faune dulcicole, datati 6350±40 anni b.p. (data calibrata 5380-5280 a.c. – beta 193206) col metodo del radiocarbonio. essi testimoniano che già in precedenza l’area palustre era isolata dal mare. tuttavia, non conoscendo la distribuzione areale di tali sedimenti, non è possibile stabilire se si sono deposti esclusivamente alle spalle dei cordoni litorali individuabili a livello del piano campagna (e quindi siano geneticamente legati a questi) o se sono correlati ad altri cordoni litorali attualmente non visibili in superficie. 2.1.1 i cordoni interrotti della foce del f. arrone e dell’area di focene nel tratto finale del fiume arrone e nella zona di focene sono state rilevate interessanti situazioni morfologiche (fig. 1, 2, 3). il fiume arrone (fig. 1), emissario del lago di bracciano, nel tratto in cui attraversa il depositi deltizi del tevere, si presenta come un corso d’acqua chiaramente pensile. i suoi sedimenti alluvionali si trovano a quote superiori ai depositi palustri di le pagliete e di 483evoluzione tardo olocenica ... fig. 3 ricostruzione delle fasi di modellamento e di erosione dei cordoni litorali presenti nell'area ad est di focene. legenda: i viii = cordoni litorali dalla prima alla ottava fase; apc = aree occupate da sedimenti palustri, alluvionali e colluviali; d = canali di drenaggio sedimentation and erosion phases of the beach ridges in the area east of focene. legend: i viii = beach ridges from the first to the eighth phase; apc = areas occupied by marshy, alluvial and colluvial sediments; d = drainage channels maccarese. quindi l’arrone, con i suoi depositi, ha prodotto la divisione di una palude che avrebbe potuto essere continua da le pagliete a campo salino. inoltre, grazie alla sua pensilità, il fiume ha sovralluvionato quasi tutta la serie dei cordoni litorali delle varie fasi, ad eccezione dei più recenti. le fotografie aeree mostrano tracce di vecchi alvei del fiume diretti verso lo stagno di maccarese, a testimonianza del fatto che il fiume pensile poteva rompere gli argini naturali e confluire nella palude di maccarese. una situazione morfologica di estremo interesse, mai discussa da autori precedenti, è stata, poi, rilevata nell’area ad est di focene, ove i cordoni litorali di varie fasi sono chiaramente interrotti ed erosi. esaminando l’andamento dei cordoni litorali (fig. 2), occorre rilevare che quelli compresi tra la seconda fase e la parte più antica di quelli della sesta fase, sono interrotti per un lungo tratto. i cordoni litorali successivi sono interessati solo da una stretta incisione. in corrispondenza di detta incisione i cordoni litorali della settima e della parte iniziale della ottava fase cambiano localmente il loro andamento, entrando parzialmente in essa (fig. 2). le interruzioni debbono essere state prodotte dallo sfondamento dei cordoni litorali. osservando in dettaglio la morfologia di alcuni cordoni possiamo notare che si sono verificate varie fasi di sfondamento, che hanno aperto estesi varchi e messo in comunicazione le paludi col mare, seguite da fasi di sviluppo di nuovi cordoni litorali, che hanno nuovamente separato le paludi dal mare. un primo sfondamento dei cordoni litorali è avvenuto dopo la formazione dei cordoni della terza fase (fig.3). l’incisione venne sigillata poi dai cordoni litorali della quarta e della quinta fase che ancora sbarrano una parte del varco. un nuovo sfondamento dei cordoni litorali ebbe luogo dopo la sedimentazione dei cordoni della quinta fase: l’incisione venne poi chiusa, almeno parzialmente, dai cordoni della sesta fase, che occupano ancora attualmente una parte del varco. in seguito anche una parte dei cordoni della sesta fase fu erosa ma l’incisione venne chiusa, almeno parzialmente, da altri cordoni formati nel corso della stessa fase. alcuni dati necessari per l’inquadramento cronologico degli sfondamenti dei cordoni litorali possono essere tratti dalla interpretazione di sequenze stratigrafiche presenti nell’area occupata, prima della bonifica, dallo stagno di maccarese. nelle trincee scavate per uno studio geo-archeologico, in collaborazione con la soprintendenza archeologica di ostia, il museo delle origini dell’università “la sapienza” di roma ed il consorzio cirf, in corso nella zona nord di campo salino, è stata rilevata la stratigrafia degli ultimi 5 metri di sedimenti palustri. la serie di sedimenti, ancora in corso di studio, coincide fondamentalmente con quelle descritte dagli autori precedenti (dragone et al., 1967; belluomini et al. 1986; bellotti et al., 1987,1989,1994,1995; chiocci & milli, 1995; amorosi & milli, 2001) ma è stata osservata con grande dettaglio con trincee molto estese: queste hanno permesso di identificare anche alcune superfici di erosione, difficilmente individuabili nelle carote prelevate con sondaggi meccanici. alla base della sequenza esaminata (fig. 4) sono presenti limi grigi con gasteropodi dulcicoli (lymnaea stagnalis, bithynia tentaculata) sui quali appoggiano limi marrone chiaro potenti circa 80 cm, ricchi di resti vegetali alla base e di gasteropodi dulcicoli (lymnaea stagnalis, bithynia tentaculata). un campione di limi ricchi di resti vegetali è stato datato col metodo del radiocarbonio ed ha fornito una età di 6350±40 anni b.p. (data calibrata 5380-5280 a.c. – beta 193206). seguono limi torbosi e torbe contenenti molti tronchi e frammenti di legno, con gasteropodi dulcicoli, gli stessi depositi datati da belluomini et al. (1986) nell’area dell’aeroporto e da giraudi (2002a) nell’area di maccarese. l’età di tali sedimenti è compresa tra circa 4042-3792 anni a.c. e 3140-2900 anni a.c.; un campione di legno proveniente dalle torbe di campo salino è stato datato ed ha fornito un’età radiocarbonio di 4360±70 bp (data calibrata 3320-2880 a.c. beta 156389), compatibile con le età ottenute sui campioni degli altri siti. 484 c. giraudi fig. 4 serie stratigrafica rilevata lungo trincee scavate a campo salino stratigraphic series surveyed along trenches dug at campo salino su torbe e limi torbosi appoggiano, tramite una netta superficie di erosione (s.e.1), argille limose grigio chiare ed un’alternanza di limi e limi argillosi grigio chiari e grigio più scuri, contenenti resti vegetali e gasteropodi dulcicoli (lymnaea stagnalis, planorbarius corneus, planorbis planorbis, bithynia tentaculata). seguono poi limi argillosi torbosi grigio-nerastri e limi grigi, contenenti gasteropodi dulcicoli (lymnaea stagnalis, bithynia tentaculata). i limi grigi, che rappresentano i sedimenti meno ricchi di sostanze organiche e più grossolani incontrati nell’area, aumentano di potenza e granulometria nella zona più vicina all’alveo del tevere: vengono quindi interpretati come sedimenti alluvionali deposti nella palude dalle acque di esondazione del tevere. una conchiglia di bithynia tentaculata, contenuta nei limi grigi, datata col metodo del radiocarbonio, ha fornito un’età di 2690±40 b.p. (data calibrata: 910-800 a.c. beta 193208). al tetto dei limi grigi è presente una netta superficie di erosione (s.e.2) sulla quale poggiano sedimenti limosi grigio-azzurrognoli, contenenti bivalvi di ambiente salmastro (cerastoderma edule, abra alba, hydrobia acuta): tra i limi con faune di ambiente salmastro sono presenti due livelli potenti pochi centimetri di limi torbosi con gasteropodi dulcicoli (planorbarius corneus, bithynia tentaculata), indice di temporanei ritorni a condizioni di palude di acqua dolce. i sedimenti descritti sono precedenti alla esecuzione di lavori per lo sfruttamento delle paludi ad opera dei romani, datati al i secolo d.c. (morelli et al., 2004). al tetto dei limi grigio azzurrognoli è presente una nuova superficie di erosione (s.e.3) sulla quale poggiano altri limi, aventi lo stesso colore dei precedenti, con faune di ambiente salmastro (cerastoderma edule, abra alba, hydrobia acuta). tali limi sono penecontemporanei e posteriori alle opere romane del i sec. d.c. visto che le età delle fasi erosive sono compatibili con quelle dei cordoni litorali erosi, si assume che le tre importanti superfici di erosione individuate siano collegate a variazioni ambientali prodotte dagli sfondamenti dei cordoni litorali. il primo sfondamento (responsabile dello sviluppo della superficie di erosione s.e.1) é quindi databile ad un periodo successivo a 3320-2880 anni a.c. ed ha prodotto l’erosione dei cordoni della iii fase, che hanno un’età prossima a 3140-2900 anni a.c. anche nella serie stratigrafica rilevata presso il sito eneolitico di le cerquete, a maccarese, é presente una superficie di erosione successiva ad una fase di pedogenesi che ha prodotto un crostone calcareo datato a 3660±40 anni radiocarbonio bp (data calibrata 2140-1920 a.c.). tale superficie di erosione ha età compatibile con la s.e.1 di campo salino e può essere coeva. assumendo che sia valida la correlazione, si deduce che i cordoni litorali della quarta fase, che più tardi hanno chiuso l’incisione, sarebbero più recenti di tale data. il secondo sfondamento (responsabile dello sviluppo della superficie di erosione s.e.2) é successivo alla sedimentazione dei limi alluvionali contenenti la data 910-800 a.c.: esso ha prodotto l’erosione dei cordoni litorali della quinta fase e permesso l’ingressione di acqua marina e lo sviluppo di una laguna salmastra. da questo dato si desume anche che i cordoni litorali della quinta fase (formatisi prima del secondo sfondamento) debbono essere penecontemporanei ai limi grigi di origine alluvionale contenenti la data di 910-800 a.c. la tradizione romana, riportata a partire da ennio (iii sec. a.c.), ricorda che la fondazione di un insediamento romano ad ostia tiberina, in una località non precisata sulla sponda meridionale della foce del tevere, risale al 620 a.c.; l’insediamento aveva lo scopo di controllare le foci del tevere e di contrastare il potere della città etrusca di veio sulla zona delle saline, poste a nord della foce del fiume. se si accetta la datazione dell’attività di estrazione del sale, riportata dalla tradizione romana, concordante con altre informazioni storico-archeologche, si deve ammettere che l’ingressione marina deve essere avvenuta almeno nel vii secolo a.c.: tale datazione non contrasta con i dati geologici e può quindi essere accettata. il secondo sfondamento dei cordoni litorali deve quindi risalire al periodo compreso tra ix-x e vii secolo a.c. il terzo sfondamento (responsabile dello sviluppo della superficie di erosione s.e.3) è successivo al periodo iniziale della sedimentazione dei cordoni litorali della sesta fase (post iv sec a.c.) e penecontemporaneo o di poco precedente ai lavori di costruzione del porto di claudio che iniziarono nel 42 d.c. lo sfondamento dei cordoni litorali può essere dovuta all’arretramento della linea di costa, ma potrebbe anche essere dovuta a tracimazione delle acque delle paludi retrodunari verso il mare e agli interventi antropici. per ora non si hanno elementi oggettivi per scegliere tra le varie ipotesi. tuttavia la penecontemporaneità tra l’ultimo sfondamento dei cordoni, le opere romane nell’area di campo salino, segnalate da morelli et. al. (2004), e la costruzione del porto di claudio, suggerisce che lo sfondamento possa essere stato influenzato dagli interventi antropici. non si può, inoltre, escludere del tutto che lo sfondamento dei cordoni litorali della quinta fase sia stato favorito dagli etruschi almeno a partire dal vii secolo a.c. per impiantare le saline. anche a sud del tevere (presso l’attuale ostia antica) erano presenti saline nel vii secolo: in questa zona non si notano sfondamenti dei cordoni litorali e le saline dovevano quindi essere collegate al mare attraverso un canale artificiale simile o coincidente con quello che è stato utilizzzato fino al xix secolo. appare fondamentale, per l’impatto che ha avuto sull’evoluzione dello stagno di maccarese, lo sfondamento che ha dato luogo alla superficie di erosione s.e.2 (successiva alla data 910-800 a.c. e precedente al vii secolo a.c.): a partire dal quel momento le paludi di acqua dolce che perduravano almeno dal 5380-5280 cal a.c. si trasformarono, salvo brevi interruzioni, in lagune di acqua salmastra, grazie al collegamento col mare. solo nel corso della fase di progradazione moderna del delta, con la sedimentazione di fasce estesissime di cordoni litorali, i collegamenti col mare vennero chiusi e le acque dello stagno tornarono ad essere oligoaline e poterono superare il livello del mare, tanto che il livello dello stagno di maccarese variava stagionalmente, nel periodo appena precedente la bonifica, tra 40 e 80 cm sul livello del mare. 2.2 gli antichi canali di drenaggio di le pagliete e di maccarese l’osservazione dettagliata delle fotografie aeree ha permesso di rilevare che, ben al di fuori dell’area 485evoluzione tardo olocenica ... sulla quale sono intervenuti i lavori dei porti nel periodo imperiale romano, sono presenti i resti di due canali emissari delle paludi di le pagliete e di maccarese, mai segnalati in precedenza. in fotografia aerea sono ancora visibili, infatti, i resti di scavi, stretti ed allungati, di forma regolare (rappresentati in fig. 1 come simboli dpa e dpm) che tagliano i cordoni litorali di varie fasi fino a quelli della parte iniziale della vi fase e sono sigillati da altri cordoni della vi fase. vi sarebbe quindi una coincidenza cronologica tra il periodo nel corso del quale sono stati scavati i canali de le pagliete e di maccarese, il periodo in cui è avvenuto il terzo sfondamento dei cordoni nella zona ad est di focene e la costruzione del porto di claudio. 2.3 gli alvei di rotta fluviale di le vignole un'altra situazione morfologica rilevata dalle fotografie aeree, in località le vignole, poco a valle dell’area ove il fiume entra nella piana deltizia, merita di essere puntualizzata. presso le vignole (fig.2), è stata individuata la presenza di piccoli ventagli di crevassa, distinguibili in base a morfologia e litologia, e di tracce di alvei prodottisi per superamento e rottura degli argini naturali del tevere ad opera delle acque di piena. tali alvei sono indicati da blande depressioni del piano campagna, allungate verso nw, ben individuabili su alcune fotografie aeree perché presentano diverso grado di umidità dei suoli rispetto alle aree circostanti. anche attualmente, in quella zona, l’alveo fluviale scorre tra argini naturali (oltre a quelli artificiali) ed i sedimenti di tali argini sovralluvionano parzialmente gli alvei di rotta fluviale appena descritti. non si posseggono elementi diretti per la datazione delle rotture di argini in zona le vignole, tuttavia essendo l’area superata dall’antica via portuense (costruita per collegare i porti imperiali con roma) sembra probabile che si tratti, prevalentemente, di morfologie precedenti al i secolo d.c. i limi grigi di origine alluvionale presenti a campo salino, contenenti la data di 910 – 800 a.c. sono gli unici interpretabili come sedimenti alluvionali, deposti da acque torbide provenienti dalle rotture di argine del tevere: gli alvei di rotta fluviale sarebbero quindi databili a tale periodo. segre (1986), osservando probabilmente gli stessi indizi morfologici, ipotizzò che presso le vignole l’alveo del tevere deviasse verso nord, per sfociare nella palude di maccarese. nella zona appena ad est dei porti imperiali, i depositi alluvionali del tevere sono tagliati da un canale, ancora parzialmente visibile in fotografia aerea, che fa parte delle opere contemporanee al porto di claudio, del i sec. d.c.: il canale appare però parzialmente riempito da depositi alluvionali successivi: in quest’area si ripete quindi la situazione descritta per le vignole. sarebbero stati i sedimenti alluvionali, databili dal ix-x secolo a.c. in poi, a coprire i cordoni litorali nella fascia compresa tra la zona ad oriente dei porti imperiali e la zona di ostia antica ed a produrre la netta separazione morfologica ancora oggi visibile tra zona a nord e a sud del tevere. 3 discussione in base ai dati riportati nei capitoli precedenti è possibile inquadrare cronologicamente lo sviluppo dei cordoni litorali (fig. 5) e di conseguenza datare l’evolu486 c. giraudi fig. 5 elementi cronologici utilizzati per la datazione dei cordoni litorali. chronological data used for dating beach ridges zione del delta, a partire da 4000 anni cal. a.c., e gli spostamenti della foce del tevere. i cordoni litorali delle prime due fasi possono essere datati (fig. 5) rispettivamente ad un periodo precedente a 4042-3792 e a 3275-2930 anni a.c., mentre quelli della terza fase sono databili al periodo attorno a 3275-2930 anni a.c. i cordoni della quarta fase si sono formati in un momento successivo a 2140-1920 anni a.c. e precedente al 1000-1300 a.c., quelli della quinta in un periodo attorno a 910-800 anni a.c. i cordoni della sesta fase si sono formati a partire da un momento successivo al iv sec a.c. (a partire dal i secolo a.c. interpretando le informazioni di plinio il vecchio) fino ad un momento precedente al 1400 d.c., mentre i cordoni della settima ed ottava fase sono tutti successivi al 1400 d.c. la forma e l’estensione dei cordoni litorali delle varie fasi permettono poi di ricostruire gli spostamenti della foce del tevere. appare chiaro che, almeno in corrispondenza della formazione dei cordoni conservati della seconda e della terza fase (cioè fino a circa 31402900 anni a.c.), la foce del fiume doveva situarsi in un luogo, non precisabile in dettaglio, posto presso i porti imperiali. le cuspidi dei cordoni litorali conservati della quarta e quinta fase (rispettivamente più antichi di 1000-1300 anni a.c. i primi e databili attorno a 910-800 anni a.c., i secondi) indicano con precisione che l’alveo del tevere coincideva con una parte dell’attuale ramo di fiumicino e la foce doveva trovarsi a sw dei porti imperiali. dragone et al., (1967) avevano già ipotizzato che nel x sec. a.c. la foce del tevere fosse nella zona dei porti imperiali. l’interpretazione dei dati geologici e di quelli storici sulla fondazione di ostia testimoniano che, in un momento successivo a 910-800 anni a.c. e precedente al iv secolo a.c., deve essere avvenuto uno spostamento verso sud della foce del tevere. il fiume, probabilmente, sboccò in un primo tempo nell’area paludosa presente alle spalle di ostia antica; il livello dell’acqua nelle paludi dovette aumentare finché si aprì un varco nei cordoni litorali della zona appena ad ovest del sito dove sorse, poi, la città romana di ostia. l’ultimo tratto del tevere assunse quindi una posizione molto vicina a quella attuale. dopo la diversione dell’alveo verso sud, si formarono i cordoni litorali che produssero la prima cuspide nella zona ad ovest di ostia. nel corso della sedimentazione di tali cordoni vennero eseguiti i lavori per la costruzione dei porti imperiali del i e ii secolo d.c. e venne scavato il ramo fluviale artificiale di fiumicino. questo ramo per un certo tratto ricalcò l’alveo fluviale abbandonato a causa della diversione precedente al iv secolo a.c. si può notare altresì, che i cordoni dell’ottava fase (databili dal xvi al xix secolo d.c. e che si sono prodotti a seguito di una lunga fase di piene eccezionali che trasportavano grandi quantità di sedimenti) occupano un’area pari o superiore a quella occupata dai cordoni di tutte le fasi precedenti. tra i cordoni più antichi del xvi secolo d.c., quelli della quarta fase sono i più estesi, seguiti da quelli della terza. i cordoni della sesta fase presentano poi una peculiarità: sono stretti e poco estesi a sud della foce del tevere, mentre si allungano e si ampliano molto verso nord. una situazione simile è tipica anche dei cordoni litorali della settima fase, che sono poco estesi, ma disposti in modo asimmetrico, più allungati verso nord. 3.1 – morfologia dei cordoni litorali e fasi di progradazione e regresso del delta l’andamento dei cordoni litorali delle varie fasi, evidenzia che l’avanzamento del delta non è stato continuo, ma è stato caratterizzato da periodi di progradazione, nel corso dei quali si sedimentavano i cordoni litorali, interrotti da periodi di stasi o regressione del margine del delta o di parte del margine. periodi di regressione del delta sono poi indicati dai cordoni litorali che tagliano quelli più antichi: è il caso dei cordoni della seconda fase che tagliano quelli della prima, dei cordoni della sesta fase che tagliano quelli della quinta e dei cordoni della settima fase che tagliano quelli della sesta. la limitata estensione verso sud dei cordoni della sesta e settima fase può essere stata determinata da erosioni successive: l’azione erosiva può essere però negata se si assume che, per quel periodo, le correnti litoranee dirette in prevalenza verso nord abbiano avuto un ruolo nettamente più importante nel trasporto costiero dei sedimenti rispetto ai periodi precedenti e successivi. anche gli sfondamenti dei cordoni litorali posteriori alla terza ed alla quinta fase, e quelli compresi nell’ambito della sesta fase potrebbero implicare una regressione della linea di costa. i dati storici indicano poi un arretramento della linea di riva nel iii secolo d.c., che avrebbe interrotto per un certo periodo la sedimentazione dei cordoni della sesta fase. procopio di cesarea (vi sec d.c.) descrive l’area del delta e riporta le distanze tra la biforcazione del tevere e il mare e fra i due rami del tevere: se i dati fossero attendibili si avrebbe la prova che nel vi secolo d.c. la linea di costa era più avanzata di quella precedente il xv secolo d.c. ed una ulteriore conferma dell’arretramento della linea di costa nel periodo successivo alla formazione dei cordoni litorali della sesta fase. nel complesso, la più chiara fase di regressione del delta, particolarmente evidente nella zona dei porti imperiali e di ostia, è quella verificatasi nel periodo post-romano, prima della sedimentazione dei cordoni della settima fase. in alcuni dipinti del xvi secolo (all’inizio della forte fase di progradazione del delta) sono rappresentati, nella zona ad ovest dei porti imperiali, ruderi immersi nel mare. questi ruderi non sono necessariamente attribuibili a resti di opere portuali costruite in acqua, ma potrebbero semplicemente essere manufatti costruiti sulla terraferma, trovatisi poi in acqua a seguito della forte regressione del delta avvenuto in epoca postromana. nel periodo precedente al ii secolo a.c. potrebbero essersi verificati arretramenti della linea di costa ancora più notevoli, legati all’aumento di livello del mare. secondo antonioli & leoni (1998), che hanno costruito una curva della risalita olocenica di livello del mare basata sullo studio di insediamenti archeologici costieri, tra i quali molti relativi al lazio, il livello marino doveva essere: circa 6 m sotto il livello attuale attorno a 5000 anni fa; 487evoluzione tardo olocenica ... circa 4 m sotto il livello attuale attorno a 4000 anni fa; circa 2,5 m sotto il livello attuale circa 3000 anni fa; circa 1,7 m sotto il livello attuale attorno a 2400 anni fa; pochi decimetri sotto il livello attuale attorno a 2000 anni fa. anche secondo i dati di bellotti et al (1995) sul delta del tevere, il livello del mare attorno a 5000 anni radiocarbonio b.p. era ancora basso, circa 5 m al di sotto di quello attuale, ed in seguito risalì gradualmente. quindi, contemporaneamente allo sviluppo dei cordoni litorali dalla prima fino alla sesta fase, è avvenuto un aumento di livello del mare ancora sensibile. l’ingressione marina contrasta l’avanzamento del delta e tende a produrre l’arretramento della linea di costa. l’aumento di livello del mare può avere causato la sedimentazione di depositi marini sui cordoni litorali, come dimostrato da bellotti et al. (1994,1995) per il tardo pleistocene superiore e la prima metà dell’olocene, e l’erosione di parte dei cordoni litorali precedenti l’ingressione marina. in base alle quote del livello marino, è lecito ipotizzare che i cordoni litorali più antichi (conservati attualmente a quote superiori al livello del mare) si spingessero verso mare fino a quote inferiori di circa 4-5 m rispetto al livello marino attuale, e che occupassero un’area di gran lunga più estesa rispetto a quella attuale: gran parte dell’areale da loro occupato deve essere stato coperto da cordoni litorali successivi o eroso dal mare in risalita. tutti i gruppi di cordoni litorali del periodo precedente al 1500 d.c. debbono essere stati più estesi di quanto risulta attualmente in base ai dati di superficie e debbono essere stati parzialmente coperti e/o erosi. un’idea dell’arretramento dei cordoni della quinta e sesta fase può essere dedotta dalla fig. 2. un lembo isolato di cordoni della quinta fase è presente al margine nord del porto di claudio, in corrispondenza della terminazione orientale del molo. l’estremità occidentale di tale lembo indica che la linea di costa nel corso della quinta fase doveva trovarsi almeno 400 m più ad ovest del margine dei cordoni della stessa fase attualmente osservabili più a nord. anche per i cordoni della sesta fase può essere valutata l’estensione 488 c. giraudi fig. 6 – posizione della linea di costa in vari periodi della seconda metà dell’olocene. sul grafico sono segnate le posizioni della linea di costa prima dello sviluppo dei cordoni litorali delle varie fasi: infatti, poiché i cordoni più esterni di ogni singola fase sono stati erosi o coperti, non è possibile ricostruire l’effettivo andamento della linea di costa alla fine di ogni singola fase di avanzamento del delta. position of coastline in various periods in the latter half of the holocene. the positions of the coastline before the development of the beach ridges in the various phases are marked on the graph. in fact, as the outermost ridges in each phase were eroded or covered, it is not possible to recognize the coastline at the end of each single phase of delta advance. verso ovest. come visibile in fotografia aerea, e rappresentato in fig. 2, la fossa traiana, l’alveo artificiale scavato dai romani, nell’ultimo tratto ha un andamento diverso dal ramo fluviale di fiumicino ed appare colmata da sedimenti fluviali e sbarrata da cordoni litorali. nell’opera originaria non era presente la curva del fiume verso wnw ma l’alveo continuava per alcune centinaia di metri, seguendo la direzione del tratto adiacente della fossa traiana. si può ragionevolmente ritenere che la linea di costa del ii secolo d.c. si situasse presso il tratto finale della traccia, vale a dire circa 300-400 m più ad ovest dei cordoni più esterni della sesta fase attualmente conservati. l’arretramento della costa successiva al ii secolo d.c. in questa zona del delta sarebbe stato di diverse centinaia di metri. la sproporzione tra l’area occupata dai cordoni litorali della ottava fase e quelli delle fasi più antiche, evidenziata da tutti gli autori precedenti, potrebbe essere solo apparente: i cordoni dell’ottava fase sono ancora quasi completamente conservati mentre quelli più antichi sono stati coperti da sedimenti più recenti o erosi, ma potrebbero essere stati molto estesi ed essere ancora presenti nel sottosuolo. la fortissima avanzata posteriore al xvi secolo d.c. potrebbe, perciò, non essere molto diversa da alcune di quelle verificatesi in precedenza: per spiegare l’avanzamento del delta negli ultimi secoli potrebbe non essere necessario invocare eccezionali eventi naturali ed interventi umani straordinari. 3.2 correlazione tra fasi di progradazione ed arretramento del delta e variazioni climatico-ambientali le fasi di avanzata e di regressione del delta del tevere nella seconda metà dell’olocene debbono essere state provocate, oltre che dall’influenza delle oscillazioni glacio-eustatiche di livello del mare, anche da variazioni ambientali avvenute nel bacino di alimentazione del fiume. le variazioni ambientali, specialmente quelle di epoca romana e moderna, possono anche essere dovute ad interventi antropici sull’alveo o sul suo bacino. già bellotti et al. (1994) avevano ipotizzato una correlazione tra l’avanzata del delta avvenuta a partire dal xv secolo ed il periodo climatico conosciuto come piccola età glaciale. tali autori avevano anche stabilito una correlazione più generale tra i periodi di avanzamento del delta e le fasi climatiche caratterizzate da forti alluvioni nel corso del periodo romano e postromano. giraudi (in stampa) studiando e datando la serie dei sedimenti alluvionali presenti a campo imperatore ed in altre località di alta montagna dell’appennino, ha constatato che, per gli ultimi 2200 anni, vi è una chiara correlazione tra fasi alluvionali registrate dai sedimenti in montagna, periodi di maggior frequenza delle alluvioni del tevere riportati in camuffo & enzi (1994), fasi di avanzata del delta tiberino, periodi di alto livello dell’acqua dei laghi trasimeno e fucino e fasi di avanzata del ghiacciaio del calderone, sul gran sasso d’italia. in particolare questa corrispondenza si verifica dal ii sec. a.c. alle fasi iniziali del i sec. d.c. (quando si formavano i cordoni litorali della parte iniziale della sesta fase), dal vi al ix sec d.c. (quando, verosimilmente, si formavano i cordoni litorali della parte medio-finale della sesta fase), e dal xv al xix secolo d.c. (quando si formavano i cordoni litorali della settima e ottava fase). si verifica inoltre una corrispondenza tra fasi di sviluppo dei suoli in montagna e periodi caratterizzati da scarsa attività alluvionale del tevere, quindi nei secoli iii-v d.c. e x-xiii d.c. in questi stessi periodi si verificarono due arretramenti del delta: quello che ha interrotto per un certo periodo la sedimentazione dei cordoni litorali della sesta fase e quello precedente la sedimentazione dei cordoni della settima fase. le variazioni ambientali avvenute sull’appennino, quindi, debbono avere influenzato il regime idraulico del tevere e la quantità di sedimenti trasportati al delta. in particolare durante i periodi più freddi e umidi, si verificavano più alluvioni ed un maggiore trasporto solido, mentre durante quelli più caldi diminuivano le alluvioni ed il trasporto solido a causa dell’espansione della vegetazione in montagna. in base ai dati esposti ed assumendo che almeno le variazioni del ghiacciaio del calderone non possano essere state influenzate dagli interventi umani, è possibile dedurre che le fasi di progradazione e di ritiro del delta sono state controllate, principalmente, dalle variazioni climatiche, anche se è probabile un certo grado di influenza degli interventi antropici sul tevere e sul delta. se si assume che le fasi di progradazione del delta siano collegate a periodi di clima freddo e umido, è lecito estendere indietro nel tempo la correlazione tra avanzamenti del delta ed eventi climatici registrati in appennino. in base ai lavori di giraudi (2002b, 2003a, 2004) sulle variazioni del ghiacciaio del calderone, giraudi (2003b) sui depositi alluvionali del gran sasso e giraudi (1998) sulle variazioni di livello del fucino, è possibile stabilire che nelle zone montane dell’appennino si sono verificati, negli ultimi 6000 anni circa, alcuni periodi freddi e umidi indicati da: 1un’espansione del ghiacciaio del calderone databile attorno a 905-775 a.c. ed un aumento di livello del fucino databile attorno al 900-800 a.c.; 2un’espansione del ghiacciaio del calderone databile ad un momento successivo a 2570-2140 anni a.c. ed un aumento di livello del fucino databile attorno al 2880-2460 a.c.; 3un aumento di livello del fucino datato 3000-3300 a.c.; 4un aumento di livello del fucino datato 4250-3770 a.c. gli eventi segnalati al punto 1 (databili attorno al 905-775 a.c. ed al 900-800 a.c.), sono coevi con la fase di alluvionamento e di avanzamento del delta che produsse i cordoni della quinta fase databile attorno a 910-800 a.c. gli eventi segnalati al punto 2 (successivi a 25702140 a.c.) potrebbero essere coevi con la fase di sedimentazione dei cordoni litorali della quarta fase, di età compresa tra 2140 e 1920 anni a.c. e 1000-1300 anni a.c. l’evento segnalato al punto 3 (datato 3000-3300 a.c.) è coevo con la formazione dei cordoni litorali della terza fase, datati attorno a 3275-2930 a.c. l’evento relativo al punto 4 potrebbe essere coevo alla sedimentazione dei cordoni litorali della seconda o della prima fase, per i quali non esistono però elementi di datazione. almeno per gli eventi dei punti 1 e 3 sembra confermata la correlazione tra le fasi di avanzamento del delta e le fasi fredde e umide. 489evoluzione tardo olocenica ... 4 ipotesi sull’asimmetria del delta precedente alla settima fase di progradazione osservando la porzione settentrionale del delta, è possibile notare che la distribuzione e la morfologia dei cordoni litorali delle varie fasi mostrano, come evidenziato in precedenza, alcune situazioni peculiari ed un andamento asimmetrico. i cordoni della prima fase si estendono verso nord a partire da circa 5,5 km di distanza dal tevere, quelli della seconda fase a partire da circa 2,5-3 km dal fiume, quelli della terza fase a partire da circa 1,5 km. i cordoni litorali si originano nei pressi della foce dei fiumi e, quando questo non si verifica, possiamo assumere che nell’area compresa tra i tratti conservati e la foce del fiume essi siano stati coperti da sedimenti più recenti e/o erosi. nella zona a nord dei porti imperiali, i cordoni litorali più antichi (prima, seconda e terza fase), ad andamento rettilineo, sono disassati rispetto a quelli presenti a sud ed appaiono più arretrati verso est rispetto a questi. i rami settentrionali delle cuspidi dei cordoni litorali della iv e v fase non presentano continuità con i cordoni coevi posti più a nord e sono molto avanzati e collegati ai cordoni della porzione meridionale del tevere. esiste un limite abbastanza netto tra le due aree, che appare stretto ed allungato in senso circa est-ovest. le situazioni descritte potrebbero essere spiegate assumendo che la porzione di area deltizia posta a sud est di focene ed a nord dei porti imperiali sia soggetta a subsidenza differenziale rispetto alla zona meridionale, ma anche a quella settentrionale ove sono conservati i cordoni litorali della prima fase. la subsidenza di quest’area era già stata individuata e calcolata, ma non associata a fenomeni morfologici, da amorosi e milli (2001) che avevano ottenuto valori inferiori a 0,6 mm/anno. come conseguenza della subsidenza in area costiera si verifica una diminuzione di quota della superficie che favorisce l’ingressione marina e l’arretramento della linea di costa. tale ingressione potrebbe essere in grado di contrastare o ritardare la progradazione del delta. l’arretramento della linea di costa, denunciata dai vari cordoni litorali precedenti a quelli della settima fase, inizia bruscamente a nord di una fascia assai stretta che limita a nord la zona dei porti imperiali. la morfologia dei cordoni litorali sembra escludere che la causa vada attribuita ad un minor trasporto solido operato dalle correnti litoranee, anzi mostra chiaramente una prevalenza del trasporto verso nord: il minor grado di avanzamento del delta a nord dei porti imperiali deve quindi essere stato provocato dalla subsidenza differenziale tra aree contigue, limitate da un elemento assai netto non osservabile in superficie. se si osserva la fig.3 di bellotti et al. (1995) nella quale sono riportati gli spessori dei sedimenti della sequenza deposizionale post glaciale del delta del tevere (l’andamento semplificato delle isopache è riportato in fig. 2 nel presente lavoro) si può notare che, nel sottosuolo dell’area compresa tra i porti imperiali e focene, lo spessore dei sedimenti post-glaciali è maggiore che nel resto dell’area deltizia. secondo bellotti et al. (1995), in tale zona era presente la valle fluviale scavata dal tevere nel corso del periodo di basso livello del mare contemporaneo all’ultimo massimo glaciale. nel sottosuolo del margine settentrionale dei porti imperiali esiste quello che era il ripido versante sinistro idrografico di quella valle: la potenza dei sedimenti della sequenza deposizionale deltizia aumenta quindi decisamente in questa zona. si può perciò ipotizzare che vi sia stata subsidenza dovuta a costipazione dei sedimenti deltizi e che questa sia stata maggiore nella zona dove i depositi sono più potenti. la subsidenza differenziale potrebbe spiegare tutte le situazioni relative alla forma, alla discontinuità ed al minor grado di conservazione, in superficie, dei cordoni litorali più antichi. la subsidenza potrebbe quindi spiegare anche la presenza di un piccolo golfo nella zona di interruzione dei cordoni litorali, golfo che i romani sfruttarono e inglobarono, almeno parzialmente, nel bacino del porto di claudio. 5 i canali di le pagliete e maccarese e lo sfondamento dei cordoni della sesta fase ad est di focene come evidenziato in uno dei capitoli precedenti, vi è coincidenza tra il periodo nel corso del quale sono stati scavati i canali di drenaggio antichi de le pagliete e di maccarese ed il periodo in cui è avvenuto il terzo sfondamento dei cordoni nella zona ad est di focene: si tratta di un periodo penecontemporaneo o di poco precedente la costruzione del porto di claudio (i sec. d.c.). tuttavia, se lo sfondamento dei cordoni litorali nella zona di focene fosse stato naturale, non sarebbe stato necessario scavare un altro canale nella zona di maccarese, in quanto si trattava di un’unica laguna. la spiegazione più logica è che i lavori del canale presente nella zona di maccarese facessero parte di un intervento di gestione complessiva della laguna del settore nord del delta tiberino, lavori che comprendono anche le opere segnalate da morelli et al. (2004) a campo salino: è possibile che tra l’area di maccarese e di campo salino vi fosse una barriera artificiale. nell’ottica di una gestione complessiva delle paludi, appare ragionevole attribuire lo sfondamento dei cordoni litorali coevi allo scavo dei canali di maccarese e le pagliete a interventi artificiali eseguiti al fine di collegare meglio le paludi col mare. 6. conclusioni gli studi morfologici e stratigrafici effettuati hanno permesso di riconoscere e di datare l’evoluzione del delta del tevere con maggior dettaglio ed i principali risultati raggiunti vengono sintetizzati di seguito. l’esame morfologico ha permesso di stabilire che vi sono gruppi di cordoni litorali che costituiscono otto insiemi omogenei che possono essere seguiti sia nella zona settentrionale che meridionale del delta. i gruppi di cordoni litorali affioranti al piano campagna indicano otto fasi di avanzamento del delta: la prima fase è più 490 c. giraudi antica di circa 3700-4000 anni a.c.; la seconda più antica di 3275-2930 anni a.c.; la terza ha età prossima a 3275-2930 anni a.c.; la quarta ha età compresa tra 2140-1920 anni a.c. e 1300-1000 anni a.c.; la quinta ha età prossima a 910-800 anni a.c.; la sesta ha un’età compresa tra il iv secolo a.c. (i secolo a.c. secondo gli autori latini) ed il x secolo d.c.; la settima e l’ottava fase sono databili al periodo compreso tra il xv ed il xix secolo. e’ stato possibile stabilire che fino, almeno, al ix secolo a.c. la foce del tevere era situata in corrispondenza dell’attuale alveo di fiumicino: solo tra viii e iv secolo a.c. il fiume subì una diversione verso l’attuale foce. il delta ha subito anche varie fasi di arretramento, avvenute tra la sedimentazione dei cordoni litorali della prima e della seconda fase (età maggiore di 3275-2930 anni a.c., tra quinta e sesta fase (età compresa tra viii e i secolo a.c.), nel corso della sesta fase (iii secolo d.c.), e, quello morfologicamente più evidente, successivo ai cordoni della sesta fase, databile al medioevo (x-xiii sec). sensibili arretramenti della linea di costa, devono essere avvenuti anche tra 6000 e 2000 anni fa a causa della risalita eustatica del livello del mare e porzioni, anche estese, dei gruppi di cordoni litorali debbono quindi essere state erose o giacere coperte da sedimenti più recenti. i cordoni litorali formati nel corso della forte avanzata del delta che avvenne a partire dal xv secolo occupano attualmente un’estensione maggiore di quella dell’insieme dei cordoni di età più antica. questo fatto non implica che il loro sviluppo areale sia eccezionale: i cordoni litorali più recenti potrebbero essere più estesi solo perché conservati nella loro interezza. e’ stato rilevato che nell’area ad est di focene i cordoni litorali hanno subito vari sfondamenti nel corso del tempo: il primo dopo 3275-2930 anni a.c., il secondo in un periodo successivo a 910-800 anni a.c. e precedente al vii secolo a.c., il terzo nel corso, probabilmente, del i secolo d.c. in particolare, il secondo sfondamento ha permesso l’ingressione di acqua salata nelle paludi di acqua dolce dello stagno di maccarese che esistevano almeno dal 5300-5200 a.c. l’ultimo di questi sfondamenti sembra dovuto a interventi antropici, forse collegati alla costruzione del porto di claudio. nell’area di maccarese e di le pagliete sono stati individuati i resti di due canali artificiali di età romana che suggeriscono, insieme a manufatti presenti a campo salino, un tentativo di gestione complessiva delle paludi presenti nell’area settentrionale del delta. dal confronto tra l’evoluzione del delta, la frequenza degli eventi alluvionali del tevere a roma, le fasi climatiche registrate in appennino è emerso chiaramente che le fasi di progradazione del delta sono coeve con fasi climatiche più fredde e umide, mentre le fasi di arretramento della costa sono correlabili a periodi più caldi. l’evoluzione del delta, seppure condizionato da interventi antropici, appare essenzialmente collegata all’evoluzione climatico-ambientale dell’appennino. infine si può ipotizzare che l’asimmetrico sviluppo dei cordoni litorali a nord e a sud dell’area dei porti imperiali sia dovuto ad un diverso grado di subsidenza. anche se limitata, nel corso del tempo la subsidenza avrebbe influenzato l’evoluzione della linea di costa, favorendo la formazione di una discontinuità dei cordoni litorali nell’area a nord del ramo di fiumicino e la formazione di un piccolo golfo, nelle adiacenze del quale vennero scavati i bacini e costruite le infrastrutture del porto di claudio. ringraziamenti si ringrazia g. belluomini che ha fornito la calibrazione delle date radiocarbonio presentate nel lavoro belluomini et al. 1986. si ringraziano inoltre d. esu e c. tata per la determinazione delle malacofaune. a c. morelli e m. bedello, delle soprintendenze di ostia e dell’alto medioevo, a. manfredini, c. conati, g. carboni dell’università “la sapienza” di roma, va un particolare riconoscimento per avere favorito gli studi geologici sui siti le cerquete e campo salino. un grazie anche ad a. facciolo, m. gala, m.c. grossi, m.l. rinaldi, d. ruggeri, s. sivilli, a. tilia, per l’aiuto fornito nel corso dello studio delle trincee di campo salino. riferimenti bibliografici amenduni g. (1884) sulle opere di bonificazione della plaga litoranea dell’agro romano che comprende le paludi e gli stagni di ostia, porto, maccarese e delle terre vallive di stracciacappa, baccano, pantano e lago dei tartari. relazione del progetto generale 15/7/1880. min.ll.pp. ed. eredi botta, 1-36. amorosi a., milli s. (2001) late quaternary depositional architecture of po and tevere river deltas (italy) and worldwide comparison with coeval deltaic successions. sedimentary geology, 144, 357375. antonioli f., leoni g. (1998) siti archeologici sommersi e loro utilizzazione quali indicatori per lo studio delle variazioni recenti del livello del mare. il quaternario,11(1), 53-66. bellotti p., chiocci f.l., evangelista s., tortora p. & valeri p. (1987) la superficie di discordanza alla base del delta del tevere e le sue relazioni con la geometria del corpo deltizio. memorie della società geologica italiana, 37, 407-415. bellotti p., carboni m.g., milli s., tortora p., valeri p. (1989) la piana deltizia del fiume tevere: analisi di facies e ipotesi evolutiva dall'ultimo low stand glaciale all'attuale. giornale di geologia, ser. 3a, 51/1, 71-91. bellotti p., chiocci f.l., milli s., tortora p. & valeri p. (1994) sequence stratigraphy and depositional setting of the tiber delta. integration of high-resolution seismics, well logs, and archeological data. journal of sedimentary research, b64, 3, 416432. bellotti p., milli s., tortora p. & valeri p. (1995) physical stratigraphy and sedimentology of the late pleistocene-holocene tiber delta depositional sequence. sedimentology, 42,617-634. belluomini g., iuzzolini p., manfra l., mortari f., zalaffi m. (1986) evoluzione recente del delta del tevere. geol. rom., 25, 213-324. bocci d. (1892) il delta tiberino. giornale del genio civile, 30, 1-34. 491evoluzione tardo olocenica ... camuffo d., enzi s. (1994) cambiamenti climatici negli ultimi 2000 anni. il quaternario, 7(1), 257-266. carboni g., conati barbaro c., manfredini a. (2002) datazioni radiometriche e correlazioni con l’eneolitico dell’italia centrale. in: le dune, il lago, il mare. una comunità di villaggio dell’età del rame a maccarese. a. manfredini ed. 255-260. istituto italiano di preistoria e protostoria, firenze chiocci f.l., milli s. (1995) construction of a chronostratigraphic diagram for a high-frequency sequence: the 20 ky b.p. to present tiber depositional sequence. il quaternario, 8(2), 339-348. conti a.m. (1982) studio preliminare su materiali dell’età del ferro da ostia antica. in: iv convegno dei gruppi archeologici del lazio . gruppi archeologici d’italia, roma. dragone f., maino a., malatesta a. & segre a.g. (1967) note illustrative del foglio 149 cerveteri della carta geologica d’italia. servizio geologico, 4, 1-93. giraudi c. (1998) late pleistocene and holocene lake level variations in fucino lake (abruzzo central italy) inferred from geological, archaeological and historical data. esf workshop "palaeohydrology as reflected in lake-level changes as climatic evidence for holocene times". palaoklimaforschung, 25, 1-17. gustav fisher verlag ed. giraudi c. (2002a) evoluzione ambientale tardo-olocenica dell’area comprendente il sito eneolitico di maccarese (fiumicino). in: le dune, il lago, il mare. una comunità di villaggio dell’età del rame a maccarese. a. manfredini ed. 25-35. istituto italiano di preistoria e protostoria, firenze. giraudi c. (2002b) le oscillazioni del ghiacciaio del calderone (gran sasso d’italia, abruzzo italia centrale) e le variazioni climatiche degli ultimi 3000 anni. il quaternario, 15(2), 145-150. giraudi c. (2003a) middle pleistocene to holocene apennine glaciations (italy). il quaternario, 16, 3748. giraudi c. (2003b) i depositi alluvionali olocenici di campo imperatore (massiccio del gran sasso abruzzo). il quaternario, 16(1), 117-125. giraudi c. (2004) the apennine glaciations in italy. in: ehlers,j., gibbard, p.l. (eds.), quaternary glaciations-extent and chronology, part. i: europe. 215-224. amsterdam. elsevier. giraudi c. (in stampa) late holocene alluvial events in the central apennines (italy). the holocene. morelli c., facciolo a., gala m., grossi m.c., rinaldi m.l., ruggeri d., sivilli s., tilia a. (2004) acqua e terra: le attività umane sul limite della laguna di maccarese. poster al meeting : computer applications and quantitative methods in archaeology. beyond the artefacts digital interpretation of the past. prato, 13-17 aprile 2004. oberholtzer f. (1875) le foci del tevere. paravia. segre a.g. (1986) considerazioni sul tevere e sull’aniene nel quaternario. in: il tevere e le altre vie d’acqua del lazio antico.quaderni del centro di studio per l’archeologia etrusco-italica, 12, 9 17. testaguzza o. (1970) portus illustrazione dei porti di claudio e traiano e della città di porto a fiumicino julia editrice, roma. 492 c. giraudi ms. ricevuto il 27 ottobre 2004 testo definitivo ricevuto il 20 gennaio 2005 ms. received: october 27, 2004 final text received: january 25, 2005 imp.albianelli mmaaggnneettoossttrraattiiggrraapphhiicc ddaattiinngg ooff tthhee mmiiddddllee aanndd llaattee pplliioocceennee sseeqquueennccee iinn tthhee mmaarrcchheeaann aappeennnniinneess,, cceennttrraall iittaallyy aannddrreeaa aallbbiiaanneellllii11,, ggiinnoo ccaannttaallaammeessssaa22,, ppeettrrooss ddiiddaasskkaalloouu22,, aauurroorraa mmiiccaarreellllii22,, ggiioovvaannnnii nnaappoolleeoonnee11 && mmaarriiaa ppootteettttii22 1dipartimento di scienze della terra università di firenze (e.mail: albix@geo.unifi.it) 2università di camerino (e.mail: aurora.micarelli@unicam.it) abstract the periadriatic basin of the external apennines is reported for its fermo sector, containing a long sequence of pelites interbedding two major conglomerate complexes, in order to calibrate it to the geomagnetic polarity time scale. the studied succession begins with the 283 meters of mid pliocene pelites in the fosso morignano section, dated from the mammoth magnetochron (3.3 ma) to the latest gauss chron, and calculated by the cyclostratigraphic distribution of its continuous magnetic signal to last until 2.63 ma. the boundary with the matuyama chron (2.58 ma) is placed in the middle of the overlying conglomerate complex of mt. ascensione. the shift from the marl to gravel facies suddenly occurs 50 ky before the gauss/matuyama boundary and is followed in continuity by a new marly sequence lasting nearly 100 ky in the rotella section during the earliest reversed matuyama. a similar depositional cycle, but of shorter duration, is repeated with the offida profile: the 20 m thick basal pelites exposed in the fornace section are dated earlier than the beginning of the olduvai (1.95 ma), while the upper pelites contain almost fully the olduvai split end (1.815-1.785 ma), there included the pleistocene boundary which was dated 1.796 ma in the vrica stratotype. both profiles focused the calibration of the late pliocene and pleistocene boundaries delineated by the microfaunal content, as the globorotalia gr. crassaformis and g. inflata zones were always present throughout the fermo sector, even if their extremes were both missing. this prevented quantifying the stratigraphic relationships between the two sequences, from either the stratimetric or biostratigraphic viewpoints. the present dating revealed a missing time span of roughly 300 ky, including the short normal chron of reunion (2.15-2.14 ma), which may be though represented in other portions of the fermo sector. the correlation of their sequences to one another may be now used as a calibrated signal applied to individual biozones, from the date of nearly 3.3 ma in the mid pliocene through the pleistocene boundary. riassunto e’ stato condotto uno studio magnetostratigrafico sui sedimenti del medio e tardo pliocene della successione pelitica affiorante nel settore fermano del bacino periadriatico (marche meridionali). nella stessa successione già erano state effettuate ricerche stratigrafiche che avevano evidenziato per il suddetto intervallo la presenza delle biozone a globorotalia gr. crassaformis e a globorotalia inflata. a causa delle microfaune talora povere e prive di forme significative, non era stato possibile porre con precisione i limiti biostratigrafici e di conseguenza quelli cronostratigrafici. lo studio magnetostratigrafico ha offerto una maggiore risoluzione con la calibrazione alla scala dei tempi delle polarità geomagnetiche, e ha consentito di verificare nell’appennino centrale quanto evidenziato nello stratotipo della vrica (sulla costa ionica), cioè la presenza del breve intervallo di polarità inversa nell’olduvai terminale nel quale è stato fissato il limite plio-pleistocene. detto evento di polarità inversa è stato già messo in evidenza nella successione continentale del versante tirrenico dell’appennino settentrionale, sicchè nei due versanti la calibrazione di entrambe le serie data le fasi di sollevamento della catena. in particolare, in questa parte esterna dell’appennino, la sedimentazione ha registrato gli eventi di polarità magnetiche nell’intervallo da circa 3.3 ma a 1.7 ma e le variazioni cicliche del segnale magnetico, secondo i periodi di milankovitch, nell’intervallo 3.3-2.6 ma, in base a quanto misurato dalla magnetizzazione residua delle rocce campionate nelle stesse successioni delle analisi biostratigrafiche. nella porzione inferiore della successione, in cui 283 metri di peliti sono stati campionati nel fosso morignano, sono presenti i croni geomagnetici mammoth (3.33-3.22 ma) e kaena (3.11-3.04 ma) a polarità inversa e quello intermedio (3.22-3.11 ma), all’interno della polarità normale gauss che termina all’età di 2.58 ma. infatti, dall’analisi ciclostratigrafica e dalla conseguente velocità di sedimentazione che ne è scaturita, si può ritenere che il crono mammoth sia rappresentato praticamente tutto, mentre superiormente la successione pelitica si arresta circa 50 ka prima del limite gauss-matuyama, misurando il numero di cicli presenti nella durata dei 460 ka del crono c2an.1n. da rilevare che la ciclicità registrata con la maggiore ampiezza ricorre con uno spessore di sedimenti di poco superiore a 40 m che qui è stata interpretata come quella forzata dalle variazioni climatiche legate alla eccentricità breve (100 ka). dalle peliti del fosso morignano si passa con contatto erosivo al complesso conglomeratico del m.te dell’ascensione, che presenta uno spessore di 400 m ed è costituito da cinque corpi grossolani separati da livelli pelitici di modesto spessore. l’analisi magnetostratigrafica ha messo in evidenza che il passaggio dalla polarità normale gauss a quella inversa matuyama, che segna il limite pliocene medio-pliocene superiore a 2.58 ma, avviene nel livello arenaceo-pelitico posto tra il secondo e il terzo corpo conglomeratico. in questo stesso livello si rinviene la prima comparsa di bulimina marginata, la cui calibrazione diretta con il limite pliocene mediopliocene superiore è l’elemento biostratigrafico che caratterizza il limite piacenziano-gelasiano. si può altresì supporre che i primi due corpi del complesso conglomeratico si siano deposti nell’intervallo mancante tra la fine delle peliti e il limite gauss/matuyama, cioè negli ultimi 50 ka; la stessa durata può essere valutata per la deposizione della seconda metà circa del complesso conglomeratico, per cui la durata dell’intero complesso è plausibile in 100 ka. sia la sezione di fosso morignano che quella del monte dell’ascensione sono state riferite alla biozona a globorotalia gr. crassaformis. la sezione delle peliti di rotella, che segue in continuità i conglomerati di m.te dell’ascensione è stata misurata per uno spessore di 45 metri, e ha mostrato una magnetizzazione con polarità inversa. presupponendo anche in questa serie una velocità media di sedimentazione pari a quella calcolata per le peliti della sezione di fosso morignano, si può attribuire a tale sezione una durata dell’ordine di 100 ka. la sezione è riferita alla parte superiore della biozona a globorotalia gr. crassaformis per la presenza del livello a globorotalia puncticulata-inflata, che nel bacino periadriatico marchigiano-abruzzese si rinviene costantemente prima della comparsa di globorotalia inflata. superiormente, continua la successione pelitica con intercalato il complesso conglomeratico di offida dello spessore di 200 m, caratterizzato anch’esso, come quello di m.te dell’ascensione, da cinque corpi conglomeratici. sia le peliti che il complesso di offida sono riferiti alla biozona a globorotalia inflata. quindi, l’analisi magnetostratigrafica ha documentato la presenza del crono olduvai alla base delle peliti immediatamente sopra il complesso conglomeratico di offida. e’ probabile che il passaggio dalla polarità inversa a quella normale olduvai avvenga all’interno del complesso conglomeratico, in corrispondenza del quale non si è potuto effettuare misurazioni. il limite superiore del suddetto crono non è stato raggiunto nella successione esaminata; è stato comunque evidenziato il breve intervallo a polarità inversa, all’interno della parte terminale dell’olduvai, nel quale è stato fissato il limite p/p nello standard della vrica. key words: magnetochronologic calibration, gauss chron, olduvai chron, pleistocene boundary, northern apennines, central italy. parole chiave: calibrazione magnetocronologica, magnetocrono gauss, magnetocrono olduvai, limite plio-pleistocene, appennino settentrionale, italia centrale. il quaternario italian journal of quaternary sciences 1166(1), 2003, 171-183 172 a. albianelli et al. 11.. iinnttrroodduuccttiioonn the magnetostratigraphic study on the middle and late pliocene succession of the external apennines, central italy, was carried out in the fermo sector, one of the three sectors of the periadriatic basin in the marche region, with the aim of calibrating its chronostratigraphic age (fig. 1). in fact, the reconstructions made so far were based on the biostratigraphic correlation between a number of sections, which revealed an essentially continuous sequence, comparable with the best sections where the pliocene to pleistocene stages had been fixed. those studied in the apennines and sicily yielded the last stratigraphic landmarks, formalising the end pliocene with the gelasian stage and the “golden spike” for the pleistocene boundary stratotype by means of their magnetostratigraphic calibrations. for the present stratigraphic assessments, the numerical dates produced by the geomagnetic polarity time scale (gpts), as established by the sea-floor magnetic anomalies, was available according to the revision of the cenozoic and latest mesozoic chronostratigraphy made by berggren et al. (1995) on the magnetic chronology of cande and kent (1992; 1995). another important aim in dating this series was that the present area is closest to the calibrated continental sequences of valdarno and valtiberina of northern apennines, thus leading to the correlation of the main geological events in central italy during some of the most active tectonic phases of their uplift. in particular, this time span, that also witnessed the main climate changes affecting the recent evolution of the geological system and was recognized in the mentioned continental sequences, could be enhanced as a first evidence of the events inferred for the marine sequences by cantalamessa et al. (2002). for this purpose, the magnetic record of the geological time series was processed by cyclostratigraphic treatment, according to the procedures reported elsewhere (napoleone et al., 2003b), while a discussion of magnetostratigraphic correlations between the continental and marine sequences across the central apennines will be reported in a coming paper (napoleone et al., in manuscript). 22.. ggeeoollooggiicc sseettttiinngg aanndd bbiioossttrraattiiggrraapphhiicc aaggeess in the external apennines of central italy, the periadriatic basin was filled by an abundant pile of sediments that concluded the long lasting pelagic deposition. its continuous record in the italian peninsula, from the mesozoic platforms through the pelagic carbonates of the umbrian-marchean series, evolved during the neogene to the turbiditic sedimentation. it yielded the asset of the apennine fig. 1 geological sketch-map of the southern marche district. the pliocene and pleistocene deposits outcropping in this portion of the periadriatic basin belong to four sectors: 1) ancona sector 2) macerata sector 3) fermo sector, 4) teramo sector. their three basic units above the pre-pliocene basement are: 1. argille azzurre inferiori; 2. argille azzurre superiori; 3. sabbie e conglomerati di tetto. the sequence of the fermo sector is here investigated. schema geologico del bacino periadriatico marchigiano (settori anconetano, maceratese e fermano) e del settore di teramo. i depositi pliocenici e pleistocenici che affiorano sui terreni pre-pliocenici sono costituiti dalle argille azzurre inferiori, argille azzurre superiori e sabbie e conglomerati di tetto. lo studio ha interessato la successione nel settore di fermo. 173magnetostratigraphic dating ... ridge, and its evolution relative to the fore-deep complex system, during the messinian through the early pliocene (bigi et al., 1995; 1997; cantalamessa et al., 1986; 1997; 2002). while in the eastern side of the apennines the periadriatic basin was affected by marine sedimentation mostly with pelitic deposits, the late neogene intramontane basins were developed essentially in the western side with continental sediments. in these basins, a major uplift was recorded by the earliest gravel deposits, dated by magnetostratigraphy to have begun at 3.3 ma in the upper valdarno (napoleone et al. , 2003a). the evidences leading to the identification of the three sectors of the periadriatic basin in the marche, the sectors of ancona, macerata, and fermo are documented in the studies above quoted. these sectors underwent a differentiate evolution related to the effects, even combined, of tectonic changes and eustatic-climatic changes that conditioned the sedimentary environments, as well as depositional modalities and systems. in the fermo sector the sedimentary sequence is represented, from bottom to top, by the argille azzurre inferiori, argille azzurre superiori, sabbie e conglomerati di tetto (fig. 2). fig. 2 schematic relationships between the plio-pleistocene marine units in the external apennines. the lowermost is montefalcone (a), whose reduced sequence was not examined, overlain by the monte dell'ascensione member (b) and offida member (c). schema dei rapporti stratigrafici tra le unità della successione marina plio-pleistocenica nell’appennino esterno. l’unità di base è quella di montefalcone (a) che non è stata investigata, seguita dai membri di monte dell’ascensione (b) e di offida (c). fig. 3 view of the mt. a s c e n s i o n e gravel complex, exposed for about 400 m above the pelite marl sequence sampled in the fosso morignano section. the 5 marked levels of cong l o m e r a t e s overlie the pelite marls with a moderate angular u n c o n f o r m i t y and both are tilted to the northeast. p a n o r a m i c a del complesso del m.te dell’ascensione, con circa 400 metri di conglomerati esposti sopra le argille siltose della sezione di fosso morignano. da i a v sono indicati i 5 livelli che insieme alle peliti sono inclinati verso ne e presentano una modesta discontinuità angolare con queste ultime. 174 the argille azzurre superiori, to which the whole examined sequence belongs, are mainly formed by pelitic deposits interbedded at various levels with complex gravel bodies, as the ones of mt. ascensione and offida. three members are recognized in the whole formation: from the bottom, montefalcone, mt. ascensione and offida (fig. 2). the latter two were sampled. the mt. ascensione profile marked the new pelagic deposition after the last turbidites were emplaced in the early pliocene; the sampled section exposed in the fosso morignano is represented by 283 meters of pelites, overlain with an erosive contact by the 400 m thick conglomerates of mt. ascensione which are formed by 5 gravel bodies separated by arenaceous-pelitic thin levels (fig. 3). the end of this profile is represented by ca. 40 m of pelites measured in the rotella section. the offida profile begins with ca. 20 m of pelites sampled in the fornace section, and is overlain with an erosive contact by the 200 m thick offida conglomeratic complex (fig. 4). various authors (pieri & groppi, 1981; cremonini & ricci lucchi, 1982; cantalamessa et al., 1986; 2002) interpreted this discontinuity as the effect of a further major tectonic pulse, which led to the final asset of the apennine range. as for mt. ascensione, the 5 gravel bodies forming it are separated by thin arenaceous-pelitic levels, while the pelitic facies overlying in continuity is represented by nearly 60 m, whose uppermost portion was sampled in the colle tafone section. the ends of both profiles resulted of decisive importance for the interpretation of the biostratigraphic reconstruction, in order to reduce the range of incertitude of the globorotalia gr. crassaformis and globorotalia inflata biozones which defined the age of the sequence with further details provided by several episodes (cantalamessa et al., 2002). at the base of the succession, globorotalia bononiensis is associated with globorotalia crassaformis, and upwards the main events are represented by the onset of bulimina marginata followed by the globorotalia puncticulata-inflata bio-horizon. globorotalia inflata was first noticed in the offida gravel complex, while its absence in the underlying pelites (fornace section) was possibly related to an ecologic exclusion. this interpretation will be clarified after the magnetostratigraphic results be discussed. 33.. pprreevviioouuss ccaalliibbrraattiioonn ooff aappeenn-nniinnee sseerriieess ffoorr tthhee mmiidd aanndd llaattee pplliioocceennee aaggeess the studied marchean series will represent in italy the first calibrated one by direct magnetostratigraphic dating after the stratotype at vrica, southern italy, established for the plio-pleistocene boundary (van couvering, 1997), as both related to the gpts. this tight correlation would add a special relevance to the classical italian areas where the neogene and quaternary ages were investigated since the earliest sedimentologic and biostratigraphic studies, because the asset of the boundary stratotype would be tested throughout a long magnetostratigraphic sequence. the twofold pliocene age was used until less than a decade ago, with its late portion identified as the piacenzian stage. it was fixed in the mid eighteen hundreds in the piacenza area of the northern apennines, on famous sections which still provide detailed evidences of major changes that occurred in proximity of the plio-pleistocene boundary (raffi et al., 1989). among them, two main points were lately emphasized. the first one deals with the pliocene warm-water bivalve taxa and fishes which disappeared before the end of the piacenzian (monegatti & raffi, 2001; sorbini, 1988), as defined by pareto (1865) and used until the mentioned splitting into the gelasian new stage. this disappearence was dated within that of discoaster tamalis and d. fig. 4 an exposure of the erosive contact between the offida gravel complex (a) and the underlying pelites of the fornace section (b), in the outskirts of offida. contatto erosivo tra il complesso conglomeratico di offida (a) e le sottostanti peliti della sezione di fornace (b), alla periferia di offida. a. albianelli et al. 175 surculus confining the nannofossil biozones mnn 16b17, i.e. close to the onset of the glacial-pliocene (ciaranfi & cita, 1975; shackleton et al., 1984; zagwijn, 1992). the second point was that the sections of the area appeared inadequate to represent the transition from the end of the piacenzian to the pleistocene, due to a significant gap. this was fulfilled in the deposits of the gela sequence, southern sicily (cita & castradori, 1994; rio et al., 1994; 1997). the gelasian was there established (van couvering, 1995) for the late pliocene, and thus the best studied series of these critical ages of piacenzian and gelasian resulted in the extremes of the apennine mountain belt. however, the stratigraphic resolution in the present marchean sections was until now devoid of a similar accuracy, because of a lesser resolutive biozonation with planctonic foraminifera and poor nannoplankton preservation. on the other hand, magnetostratigraphy actually failed calibrating the p/p boundary in the northern area because of the incomplete extent of the gelasian stage and the disconformity with the pleistocene series, for the santernian stage in the santerno section (tric et al., 1991; mary et al., 1993). during the interval across these ages, tectonics must have been actively uplifting the northern apennines, and thus most deposits in the end-olduvai chron were eroded, while instead yielded at vrica the key elements to fix the “golden spike” gssp for the p/p boundary (van couvering, 1997). in central italy, in contrast, the pliocene sediments focused special attention since the mid 18 hundreds also on the continental deposits of the intermontane basins (cocchi, 1856; pareto, 1865), mainly because their vertebrate faunas contributed to the development of paleontology (nesti, 1811; 1825; cocchi, 1867), and of its later use for geochronological meanings (azzaroli, 1983; azzaroli et al., 1997). thence, several marine sequences have been studied in the range of ages between the late pliocene and early pleistocene, among which are the thick ones bordering the valdichiana basin (south of the upper valdarno) and farther to the east (beyond the watershed), in the external apennine periadriatic basins. the latter were recently investigated correlating a number of sections (cantalamessa et al., 2002). a long pliocene time span was recognised in the series, as well as its continuation into the pleistocene, but the p/p boundary was not satisfactorily identified with biostratigraphy. the main aim of the present work is for that reason to date, with the high resolution of the gpts numerical scale, one of the longest series studied for the middle and late pliocene, and likely correlate its p/p boundary with the stratotype section. under such conditions, both sides of the northern apennines in central italy would also be correlatable with the highest accuracy, their continental and marine deposits having both been dated with magnetic stratigraphy. 44.. mmaaggnneettoossttrraattiiggrraapphhyy the profiles reconstructed from the paleomagnetic measurements were sampled in the same sections studied for biostratigraphy, in order to directly calibrate the ages of the latter to the magnetochronology of the gpts dates. biostratigraphic characterization of the series was well established by the previous studies, and yielded a long mid and late pliocene sequence (cantalamessa et al., 1986; 2002; bigi et al., 1995; 1997). the magnetic polarity zonation was here established after the rock-magnetic properties had been tested, and the correlations of the biostratigraphy with it represent the main result. therefore, next chapters will mostly report on the magnetic calibrations with discussion of the results which clarify the chronostratigraphic asset of the series with the magnetic polarity zonation. 44..11 mmeetthhooddss aanndd mmaatteerriiaall magnetostratigraphy of the present sequence is in the fermo sector based on the polarity changes of the paleomagnetic vector reconstructed through the profiles, which will be shown below as the conclusive result after a series of analyses. the measurements were carried out at the magnetic laboratory of the eth in zurich, on cubic specimens taken from oriented hand-samples. some specimens were used for the tests on rockmagnetic properties, and most of them to measure the fossil vector of the natural remanent magnetization (nrm), having isolated the primary magnetization. this procedure was used by applying increasing temperatures for cleaning the paleo-vector from possible overprinted magnetizations, and thus recognizing the stable directions carried by a predominantly magnetite composition of the magnetic minerals. for this purpose the magnetic saturation of the samples and its subsequent thermal stepwise demagnetization were applied. two samples of the mt. ascensione unit (fig. 5a) showed a fig. 5 (a) saturation of the isothermal remanent magnetization (irm) in two samples from the pelite sequence of fosso morignano showing the behavior of a low coercivity mineral phase, such as magnetite (b). (a) curve di saturazione della magnetizzazione residua isoterma (irm) di due campioni della serie pelitica di fosso morignano che riportano il comportamento di bassa coercitività di una fase mineralogica come quella della magnetite (b). magnetostratigraphic dating ... 176 low coercivity behavior, typical of minerals as magnetite and sulphides. the latter are though very sensitive to temperature and at nearly 300-350 °c produce a new phase of magnetite, while in the present case all samples passed such steps without any deviations disturbing the identification of the virtual geomagnetic pole (vgp) latitudes. these ultimately led to the interpretation of the magnetic polarity zonation through the sequence, which, moreover, showed a remarkable uniformity in its magnetic mineralogy, because of the parallel trends of the nrm and susceptibility curves (fig. 5b). an example of the straight direction of the nrm decreasing values toward the origin of the axis after heating is shown in figure 6, for the representative units. from the top, two samples of reversed and norfig. 6 the zijderveld polar diagrams show the directions of the paleomagnetic vector pointing straightforward to the origin, unaffected by secondary magnetizations. thermal demagnetization by stepwise increasing temperatures did not enhance mineral changes, thus confirming that the primary magnetization was mainly carried by magnetite. una serie di diagrammi polari che mostrano le direzioni del vettore paleomagnetico puntare direttamente verso l’origine, senza particolari deviazioni indotte da magnetizzazioni secondarie sovrapposte a quella iniziale durante la deposizione. le graduali smagnetizzazioni termiche non hanno evidenziato variazioni mineralogiche, confermando perciò la presenza di magnetite come responsabile della magnetizzazione primaria. a. albianelli et al. mal polarities are shown for the offida profile. on the left diagram a typical change in both directions, inclination and declination, is shown as a field acquired in the present normal polarity which was removed since the initial steps of demagnetization. in the rotella section, only one reversed polarity is recorded, while the graphs for the mt. ascensione indicate that both signals descend from stable magnetizations of well aligned particles. another important analysis, the cyclic stratigraphy of the magnetic signature, was applied to control the magnetic stratigraphy in defining the duration of the long magnetozone at the critical change from the gauss to matuyama chron. its results are illustrated as first, because they relate to the basal sequence for a long time span through the middle pliocene and complete the polarity zonation for the magnetostratigraphic interpretation. 44..22 mmaaggnneettiicc ccyycclloossttrraattiiggrraapphhyy ooff tthhee ppiiaacceennzziiaann ppeelliitteess the paleomagnetic vector parameters, measured for the basal sequence of fosso morignano, revealed, in directions (inclination and declination) and intensities (nrm and susceptibility), a cyclostratigraphic content of the signal in the range of the milankovitch periods. the duration of the latter was well constrained by the magnetic stratigraphy, whose reliability is marked also by the parallel pattern of the nrm and susceptibility, shown in figure 5b as an evidence that the magnetic signal was carried only by all aligned fine particles. in figure 7a, only the susceptibility curve is shown; the power spectra were processed in the whole time series of 283 m, which enhanced in the diagram by the side the period distribution of the milankovitch indexforced sedimentation (fig. 7b). the procedures here applied were used for the coeval series of continental deposits in the intramontane basins, to illustrate the evaluation of the climate changes in the middle and late pliocene and as a further refinement of the magnetostratigraphic dating (napoleone et al., 2003a,b). the results from the present marine series are used straightforward with that aim of better timing the sedimentary events driven by the climate changes, and thus first discussed for the diagram of the bulk time series of the fosso morignano section. its spectrum (fig. 7b) showed only one prominent peak, the 41.8 m cycle, interpreted as the index-forced sedimentation by the short-eccentricity cycle at 100 ky, as inferred from the following magnetochronologic constraints of the polarity sequence. in the gpts (cande & kent, 1995), the late gauss chron extends over 460 ky (see also in the next chapter) and would thus contain 4.6 of such eccentricity cycles. in the actual profile, the uppermost magnetozone of normal polarity extends from top of the kaena, placed at 165 m depth, to the end of the section. at the rate of 41.8 m/100 ky its full time span should extend over a 190 m thick pile, which means that the latest gauss chron was recorded for only 165 m, from the kaena to the top, and therefore a 20-25 m slice was missing before reaching the boundary under the steady sedimentary conditions of pelitic deposition. and this also means that, at the rate just said before, a 50 ky duration was not recorded in the pelitic marls. more discussion should be done on the cyclostratigraphic content of the profile regarding the absence of the short period cycles, because the time resolution of the sampling rate was similar to that used for the continental sediments of the upper valdarno and valtiberina (napoleone et al., 2003a,b) and for the late albian pelagic carbonates of the umbrian series (napoleone & ripepe, 1989). the precession and obliquity index-forced sedimentation there produced distinct peaks, in either susceptibility and nrm spectra, or in the directions, also for the shorter periods of obliquity (40 ky) and precession (20 ky). these short period cycles were searched by processing the present 177 fig. 7 cyclostratigraphic analyses on the fosso morignano series. the continuous changes, in the time series of 283 m, of the magnetic signature (a) are processed for the susceptibility signal by the enhancement of the spectra of the period amplitudes. the whole time series evidenced a fundamental period of 41.8 m, as shown in the diagram by the side (b). the split portions, from top to 195 m, to which corresponds a date close to the base of the kaena chron shown in (c), and the lower series from there to the bottom in (d), provided quite different spectra. that one in (c) showed the same basic period at 40 m and the additional peaks at 16 m and 8 m, which coincide with the obliquity and precession-forced sedimentation of the astronomical parameters driving the climate changes, while in the lower section the cyclicities are all represented by the short-eccentricity cycle. analisi ciclostratigrafica della serie di fosso morignano. le variazioni continue del segnale magnetico della suscettività lungo la serie temporale dei 283 m di peliti (a) forniscono gli spettri di ampiezza dei periodi presenti: la serie complessiva contiene un solo periodo dominante, di 41.8 m (b), attribuito all’influsso delle variazioni astronomiche della eccentricità breve sulle condizioni climatiche, mentre, suddivisa in due porzioni, mostra tre picchi ben distinti fino a 195 m (c) corrispondenti ai periodi dell’obliquità e della precessione, e il solo picco di 40 m, fino alla base (d), che aveva dominato in tutta le serie. magnetostratigraphic dating ... series in two steps. first, the upper 195 meters, approximately containing the latest gauss and the kaena magnetochrons, were considered using the same constraints as for the entire series; it yielded the power spectrum shown in figure 7c. the magnitude of the power content was distributed in three strong peaks, at 8 m, 16m, 40m, which are exactly in the ratios of the milankovitch index periods, as recorded by various proxies (see, for example, tiedemann et al., 1994) and despite their variability (shackleton, 1995). the spectrum for the lower section, 195-283 m (fig. 7d), was more confused, and devoid of the short cycle peaks quite closely reproducing the pattern of the bulk profile of the upper spectrum (fig. 7b). such a behavior was also found for the mesozoic turbiditic carbonates of the external apennine sequence, where repeatedly short-term disturbances and well recognized in its sedimentation pattern as continuous resedimentation episodes altered the spectral content in the short period indexes (albianelli et al., 2003). in the present time series, all this is supported by the presence of strong magnetostratigraphic constraints, later shown in figure 8. the three chrons before the latest gauss (c2an.1n) are respectively lasting in the gpts 70 ky, 110 ky, 110 ky, which at the still constant rate of 40 m/100 ky would imply thicknesses of nearly 30 m, 45 m, 45 m. this is not the present case, because already the upper magnetozone, at the kaena chron, contains only a little more than half the thickness required by the fully sedimented sequence: but, even more so the underlying normal chron does. our explanation for their reduced extent is that about a 25 m section, distributed on both magnetozones, is missing and actually obliterated by a slice of sediments slipped undisturbed during the emplacement of the sequence or later. the lower portion, with reversed polarity, is even more effectively altered, up to a duplication of its thickness. the spectral distribution seems to confirm this hypothesis, because the short cycles are more disturbed by the sampling rate at 1m spacing. 44..33 mmaaggnneettoossttrraattiiggrraapphhiicc pprrooffiilleess the interpretation of the magnetic polarity zonation identified two profiles, the mt. ascensione and the offida profiles, both reaching an important boundary, the late pliocene and the pleistocene. for this purpose, all samples were demagnetized as in figure 5; the characteristic direction of each one was taken to indicate the primary magnetization, yielding the directions used to calculate the virtual geomagnetic pole (vgp) latitudes. the full set of samples represented the succession of the fossil-vector directions, and these were used for interpreting the polarity sequence in both profiles, as discussed below. 4.3.1 calibration of the mt. ascensione profile as the earliest gelasian the magnetostratigraphic sampling was scanty in the few silty-sand levels of the 400 m thick conglomerate complex of mt. ascensione. in the fine grained material between the second and third level from the base, one sample recorded a reversed polarity, above one sample with the normal polarity (fig. 8). downwards, the 283 m of the examined fosso morignano sequence, which is separated from the gravel by an erosive surfa178 a. albianelli et al. ce, showed on top a long normal polarity. its duration preceding the middle/late pliocene boundary was calculated since the lower time-marker measuring the milankovitch cycles there recognized with the criteria used for the upper valdarno and valtiberina (albianelli et al., 1999; napoleone et al., 2003a). as aforesaid, the boundary of the matuyama chron (2.58 ma) was found ca. half-way in the conglomerate complex, and the latest gauss was still incomplete in the pelite marls. the estimation of the time span needed for the conglomerate deposition was out of the biostratigraphic resolution, nor was resolved by the comparative analysis of the sedimentary characters discussed in cantalamessa et al. (2002), but provided by the cyclostratigraphic content of the susceptibility record (fig.7). in the present sequence of fosso morignano, a normal polarity was recorded from top to 165 m of stratigraphic depth, followed by nearly 30 m of reversed polarity and 20 m of normal polarity; the end section was again in a reversed magnetozone. the profile is then interpreted as made of two reversed magnetozones, prior to the latest gauss dated 3.04 ma in the gpts geochronology, and correlated with the kaena (3.113.04 ma) and mammoth (3.33-3.22 ma), respectively, with its normal chron (3.22-3.11 ma) there enclosed. these three dates represent tight constraints on the pelite series, whose extremes were also defined with a still high resolution: the upper extreme was found at 2.63 ma with an accuracy better than 10 ky from the cyclostratigraphic resolution (fig. 7c), and the lower extreme being inferred of the same order of magnitude, as the mammoth 110 ky are already represented by a thick pile of sediment. from such markers, a thinning of the short normal and a much larger thickness in the mammoth are evident, if the accumulation rate would have been steady, and accounts were given for the disturbances in sedimentation rates that affected the spectral analysis of the continuous magnetic signal. upward in the profile, above the conglomerate complex, the mt. ascensione profile was completed by the rotella section, which followed in continuity with the pelites measured for nearly 45 m. its magnetic record showed only one reversed polarity, in the earliest matuyama, for a time span which will be discussed later on, and begins 50 ky after the boundary, the normal chron of reunion not being reached. nor was it found in the exposure of the fornace pelites underlying the offida gravel complex, which still continued recording a reversed magnetozone. the sampling in it was more than 2 m spaced. 4.3.2 calibration of the offida profile to the late gelasian the composite profile shown in figure 8 assembles all sections surveyed with the magnetic stratigraphy, which are though discussed individually. for example, the uppermost section of the profile, sampled at a much closer spacing than that used for the others, contains the p/p boundary close to the end of the olduvai, in the short profile measured at the colle tafone section. also the vrica stratotype with its split olduvai is represented for comparison by the side. the p/p boundary, placed just before the end of the olduvai, is one of the most significant tie points marked on the whole profile, together with the late pliocene boundary, which had been calibrated to the gauss-matuyama 179 figure 8 the magnetochronologic conclusive asset of the series of pelitic-and-coarse deposits here studied yielded dates from nearly the base of the globorotalia gr. crassaformis of the early piacenzian to the top of globorotalia inflata biozone in the gelasian stage, concluding the pliocene in the split olduvai. the numerical dates of the gpts are 3.33 ma for the base of the mammoth, 3.22 ma for the base of the normal chron before the kaena at 3.11 ma, and 3.04 ma for the base of the latest gauss. the dates for the succeding matuyama and olduvai are a little less accurate, due to interruptions of the series: the first and longest one of 300 ky in correspondence with the reunion chron (2.15-2.14 ma), is followed by a possibly short one at the onset of the olduvai (1.95 ma). diagramma conclusivo dell’assetto magnetocronologico della serie pelitica con i suoi depositi conglomeratici, a partire quasi dalla base della biozona a globorotalia del gr. crassaformis del piacenziano inferiore fino alla fine di quella a globorotalia inflata del gelasiano, che conclude il pliocene all’interno della breve inversione alla fine dell’olduvai. le date numeriche nella scala dei tempi magnetici gpts partono da circa 3.33 ma alla base del mammoth e toccano 3.22 ma dell’intervallo a polarità normale prima del kaena a 3.11 ma e 3.04 ma dell’inizio del gauss terminale. quelle successive del matuyama e dell’olduvai sono meno accurate a causa delle interruzioni nella serie: la prima è risultata di circa 300 ka in corrispondenza del crono reunion (2.15-2.14 ma) ), e la seconda, più breve, in corrispondenza dell’inizio dell’olduvai (1.95 ma). magnetostratigraphic dating ... boundary of the gpts, at 2.58 ma. therefore, the beginning of the gelasian stage was marked by this date correlated with the middle of the conglomerate section (between its second and third boulder episode), for a time span calculated according to the previously determined tie-points. the date of the top of the underlying pelite resulted only 50 ky older than the gauss/matuyama boundary, as provided by the cyclostratigraphic record. this implies that also the upper half of the conglomerate body may be assigned the same duration of nearly 50 ky, and the overlying pelite of the rotella section would thus begin not later than 2.53 ma, while its duration will be discussed in the next chapter. the gelasian profile, in the surveyed area, was extended into a separate pelite sequence exposed in the fornace section. it still recorded a reversed polarity, interpreted as shortly preceding the onset of the olduvai, while the pelites above the conglomerate recorded a normal polarity, i.e. they were deposited during the olduvai chron. the transition should have occurred in the gravel complex. the smaller thickness of the offida gravel body, compared with that (almost double) of mt. ascensione, would not imply a shorter duration, as the same five episodes of boulder banks separated by the thin pelite levels are recognized. a half rate of deposition would account for the same time span as that in mt. ascensione, and the sedimentary conditions for such a smaller rate may be related to a more distal position from the ridge of the offida body than that of mt. ascensione. with such time constraints, the profiles of mt. ascensione and offida in figure 8 are fully correlated with the gpts, only one tie point remaining less tightly constrained, the un-defined portion of the conglomerates matching the olduvai boundary at 1.95 ma. the underlying and overlying pelites would date few tens of ky earlier and later than the boundary, respectively. the remaining olduvai profile was completed by the new sequence sampled at colle tafone, on the road from offida to castignano. this contains the uppermost olduvai with the same split interval as in the vrica stratotype, whose short reversed portion was dated 1.815 to 1.785 ma. the end of the normal chron (1.770 ma) was there not reached, but only a few meters are lacking to it, considering that nearly 10 ky are missing. 55.. ddiissccuussssiioonn oonn tthhee mmaaggnneettoocchhrroonnoollooggiicc sseettttiinngg an evaluation of dates at great resolution may be now summarized with these magnetostratigraphic details, on which the aforesaid results are based. the mt. ascensione lower profile was, indeed, better specified in its sedimentation rates, as accounted by the spectral processing of the time series. here, only the dates for the sequence above the mt. ascensione gravel complex will be further discussed. the rotella sequence was already dated 50 ky after the gauss/matuyama boundary; its duration would have been ca. 100 ky, if the sedimentation rate was the same as for the earlier pelite deposition, which was averaged at nearly 40 m/100 ky in the spectral analysis, and its date would be placed at 2.53 to 2.43 ma. the next fornace section, in the outskirts of offida, remained poorly constrained between the end-reunion (2.14 ma) and the olduvai onset (1.95 ma). previous lithoand biostratigraphic reconstructions would poorly define the uppermost globorotalia crassaformis biozone passing to the next one of globorotalia inflata, as the zonal marker is present only in the lowermost offida gravel levels. in that scheme, the fornace section would be assigned an age with a wider range of incertitude in the globorotalia crassaformis biozone, which might be reduced by the present magnetostratigraphic date, after some considerations to be pointed out. also this 20 m thick section, underlying the offida gravel body with an evident unconformity (fig. 4), would have lasted ca. 50 ky, if sedimentation remained at the same rate as before. the problem arises when considering that its magnetic signature was in a reversed polarity, and therefore its date somewhat earlier than the transition to the olduvai normal chron at 1.95 ma. this implies that the whole lower matuyama, lasting 630 ky from the boundary placed in the mt. ascensione gravel unit (2.58 ma) to the onset of the olduvai (1.95 ma) in the offida gravel unit, would be represented by less than 80 m of pelites from the rotella and fornace sections. this gap is now considered as covered elsewhere in the fermo sector, e.g. farther away in the colle cilestrino and castignano sequences. the missing part, including the reunion chron (2.15-2.14 ma), and the shortness of the sequences here prevented the spectral analysis for the milankovitch cycles recognition, and the gap could not be much better placed in the gpts. however, a finer magnetostratigraphic assignment may be attempted placing the fornace section close to the olduvai boundary, or at least younger than the reunion, presuming that the slight angular discontinuity of the offida gravel complex on it would not too much differ from the mt. ascensione one on the fosso morignano pelites. in the upper profile, lacking the cyclostratigraphic resolution, the biostratigraphic dating was unable to specify the duration of the missing portion. an upper limit for the date of the bottom of the fornace section would not be younger than 2.0 ma, and a lower limit not older than 2.14 ma. the missing sediments between the rotella and fornace sections would at least extend over 2.43 to 2.14 ma. on the other hand, the 45 m of pelites, overlying the offida conglomerate in continuity, extended over a normal interval spanning between 1.95 ma (at most, if the onset of the olduvai was on top of the conglomerate), but not reaching 1.815 ma. between these limits, its suggested date could average 1.93 ± 0.02 ma to 1.84 ± 0.02 ma, which seems a good compromise for a duration shortly longer than 100 ky within the 1.951.815 ma interval, and the allowance of 20 ky for the error bar. similarly, a duration in the order of 100 ky would not contradict an accumulation rate as the nearly 40 ky interval represented by the next 17 m section, containing the split olduvai on top of the profile. for the end of this profile, the biostratigraphic record indicated the latest gelasian age, marked by the presence of bulimina elegans-marginata, globigerina calabra, g. calida, etc. thus, the normal polarity in the uppermost marls -not in contact with those immediately overlying the offida gravel complexwould indicate the presence of the olduvai chron before its split interval, where the p/p boundary was calibrated in the vrica stratotype. all these olduvai dates provide very sharp time 180 a. albianelli et al. signals, altough that at 1.95 ma in the gpts was impossible to sample in the scanty fine-grained marls within the gravel layers of the offida complex. the overlying section was fully contained in the lower olduvai portion, whose end at 1.815 ma was found in the colle tafone section with the short reversal until 1.785 ma. in this split olduvai portion the p/p boundary was marked at 1.796 ma, and such a tight correlation thus becomes the highest geochronologic resolution ever reached on italian land exposed pliocene series, in spite of the shortness of both sections which prevented the cyclostratigraphic reconstruction. the results of the previous dates, adding to the mt. ascensione dates, summarize more than 1.5 my calibrated by several tie-points to the gpts magnetochronology, thus leading to the cumulative representation of the middle and late pliocene interval in the periadriatic basin deposits (fig. 8). starting from nearly the base of the mammoth, at a date of 3.3 ma, the continuous sedimentation in the pelitic marls recorded the kaena at 3.11 ma and the polarity event between them at 3.22 ma; the following uppermost gauss chron (3.04 ma) almost reached in the marls its end of 2.58 ma, missing only the last 50 ky, as shown in the cyclostratigraphic reconstruction. the magnetostratigraphic reconstruction yielded the occurrence of the gauss/matuyama boundary in the overlying conglomerate, which led to this important result: the mt. ascensione complex represents the stratigraphic continuation of the pelites. the possible gap involving such a deep change in the sedimentary regime would have been confined in a very few ky, which was recognized also in the adjacent intermontane basins (napoleone et al., 2003a) and will be further discussed in a forthcoming paper. at the onset of the matuyama chron, a time span of the same short duration may be lacking in the overlying marls, while a much longer one was measured after these latter of the rotella section of reversed polarity, which did not reach the reunion (2.15 ma). the section just below the offida gravel complex was biostratigraphically placed close to the p/p boundary: although its paleomagnetic vector still recorded the reversed polarity preceding the olduvai, and not necessarily too much close to the boundary from the biostratigraphic age resolution, one may mantain its date younger than the reunion. thus, the profile before the base of the olduvai can likely begin in the fornace section not later than 2.0 ma and only shortly after the reunion, and its estimated time span of nearly 50 ky could be best positioned between 2.1 ma and 2.0 ma. finally, the sampled pelitic marls above the gravel complex can be dated from shortly younger than 1.95 ma to few ky older than the short reversal at 1.815 ma, which is the lower limit of the split end-olduvai; its record would range no more than 1.93 ± 0.02 ma to 1.84 ± 0.02 ma. as already noted, both important markers, the short reunion (2.15-2.14 ma) and the olduvai onset (1.95 ma) were not found, due to interruptions of the series at their occurrence. but the uncertainties on their position are rather reduced. in particular, magnetostratigraphy dated the interruption of the former with the inferences discussed so far, although with lesser accuracy than that yielded by the cyclostratigraphic processing in the lower sequence of mt. ascensione. 66.. ccoonncclluussiioonnss the criteria for correlating the chronostratigraphic units in the pliocene periadriatic basin sequences resulted largely improved by the present magnetostratigraphic asset. occurrences of the various sedimentary events on the apennine sequences, of either marine or continental origins, could actually be detected under variable conditions, and their accurate dating provided. precise dates could be fixed for 1.5 my of the studied sequence in the fermo sector, southern marche, and with several tie-points to the geomagnetic scale gpts. a finer resolution was added by the cyclostratigraphic analysis of the continuous time series for more than 0.6 my in its lowermost interval. two profiles were reconstructed, that of mt. ascensione and that of offida. in the former, the beginning of the polarity zones was in the gauss sequence at nearly 3.3 ma of the mammoth chron, and in the latter the direct calibration to the gpts, extended almost until the end of the olduvai chron at 1.77 ma, including the plio-pleistocene boundary, which was fixed at 1.796 ma in the vrica stratotype. two more time markers in this 180 ky spanning chron added a higher resolution with its splitting, as in the stratotype section, while further increse of dating resolution in the lower sequence were obtained with spectral analysis of the continuous magnetic changes recorded through the gauss. magnetostratigraphy then revealed also polarity events of 70 and 110 ky durations, which accounted for a steady deposition rate of the upper half of these pelites, while in their lower portion the cyclostratigraphic signal was recorded somehow confused in the three polarity zones from kaena through the mammoth. another important result was found in the uppermost levels, because only 50 ky were lacking before the gauss/matuyama boundary, while magnetostratigraphy placed the latter in the mid mt. ascensione gravel complex. therefore, the reduced duration of the pelitic deposition was fully replaced by the nearly 200 meters of conglomerates without implying the removal of a noticeable part of them during the emplacement of the gravel complex. actually, magnetostratigraphy showed that in the gauss chron a slice of sediment was lacking in the kaena reversed magnetozone and in the normal one below it, while the mammoth chron was almost doubled in thickness when comparing the duration of the chrons in the gpts with the thicknesses of the magnetozones recorded in the overall 283 meters of the mt. ascensione marls. such thicknesses, and speciallly that of the mammoth chron, would be related to anomalous synsedimentary accumulation more than to changing sedimentation rates. an important find was dated in correspondence with the gauss-matuyama polarity change with the first occurrence of bulimina marginata; the fact that this form is directly calibrated to the middle-late pliocene boundary represents the biostratigraphic element characterizing the piacenzian-gelasian boundary. one more result was obtained dating the duration of the tectonic activity that shortly interrupted or reduced the deposition. in these marine deposits the first tectonic phase took place at the gauss-matuyama boundary (2.58 ma), spanning 100 ky across it, during which the 400 m thick mt. ascensione body was rapidly emplaced until the 181magnetostratigraphic dating ... earliest matuyama. thus, the new pelitic sequence deposited in continuity over the conglomerate was sampled for its first 100 ky, at rotella, while the following more than 300 ky are not present in the investigated area, and will be likely measured in the colle cilestrino and castignano sections. the basal unit of the offida profile consists of a pelitic facies similar to that exposed at the base of mt. ascensione, and is overlain by a similar gravel complex, made of the same five episodes, but only 200 m thick, with an unconformity present at its base. this phase took place at the olduvai boundary (1.95 ma), spanning 100 ky across it, and was followed in continuity by a fairly thick pelitic succession, referable to the uppermost pliocene and pleistocene. the first 60 m of this sequence were investigated, and the end of the olduvai was almost reached at the colle tafone section, on the road from offida to castignano. this chron was recorded also with the split short reversal which contained the plio-pleistocene boundary at 1.796 ma in the vrica stratotype. 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i rock glacier presenti alle quote inferiori si sono formati nel corso dell’ultimo massimo glaciale (lgm), ma il loro maggiore sviluppo ebbe luogo nelle fasi tardiglaciali. i rock glacier si rinvengono maggiormente su quei massicci caratterizzati, durante l’lgm, da limite delle nevi (ela) non molto basso: l'intero appennino settentrionale ed i massicci che avevano un ela basso, e che attualmente sono soggetti a precipitazioni molto più elevate, ne sono risultati privi. inoltre i rock glacier si sviluppavano per lo più nel corso delle fasi climatiche aride o non molto umide. dalla distribuzione areale dei rock glacier si deduce che, durante le fasi finali dell’lgm, nel tardiglaciale e nell'olocene iniziale, c'è stata, oltre che una migrazione verticale, anche uno spostamento verso nord del limite della loro area di distribuzione: quindi il limite del permafrost discontinuo montano è passato da 39°55'n a 41°45'n e poi a 42°07'n. in seguito ci fu soltanto una migrazione verticale, in quanto nel tardo olocene i rock glacier hanno potuto svilupparsi solo sulle parti sommitali dei due massicci più elevati. abstract the late pleistocene and holocene apennine rock glaciers (italy) – age, distribution and palaeoclimatic significance. rock glaciers have been found in the gran sasso, greco, maiella and velino massifs and in the breccioso, terminillo and pollino mounts. the apennine rock glaciers are inactive, with the exception, perhaps, of a very small rock glacier, which might be active. the northern apennines (fig. 1) consist of ranges up to 2165 m in height, and are formed mainly by sandstones and arenaceous marls. during the last glacial maximum (lgm) and its retreat phases, in the northern apennines many glaciers existed: the end moraines of such glaciers have been found up to about 700 m a.s.l. the studies show that during the last glacial maximum the equilibrium line altitude (ela) was between 1300 and 1550 m. no rock glaciers are reported in bibliography. photogeological and field researches, also, have not led to any results. according to current data, in the northern apennines, rock glaciers are lacking. the highest central apennine massifs (fig. 1) consist mainly of mesozoic and cenozoic carbonatic rocks. in this part of the chain lie the highest massifs of the whole apennines (gran sasso, 2912 m; maiella, 2793 m; velino 2486 m; sibillini, 2476 m). in the central apennines considerable glacial remnants are preserved, and, in particular, the features and deposits dated to the lgm and its retreat phases. the ela during lgm was between 1500 and 1700 m, in the western portion (fig. 1), and between 1600 and 2100 m in the central and eastern area. the majority of the rock glaciers so far mentioned in literature are in the central apennines. photogeological and field surveys have shown, however, that in the western portion of this part of the chain there are no rock glaciers, even in mountain areas higher than 2000 m. in the central and eastern parts, the rock glaciers are found above a minimum height of 1570 m, up to approximately 2550 m. all the rock glaciers have been found in places glaciated during the lgm, namely, mostly in valleys and on slopes facing nw, n and ne. the rock glaciers developed on glacial drift, and they often deform moraine ridges located on the threshold of the cirques. the rock glaciers least weathered and covered by scanty vegetation, looking younger, develop instead on slope waste deposits. the largest rock glaciers have been found in the maiella and velino massifs and are about 1 km long. the highest peaks of the southern apennines are mt. pollino (2267 m) and mt. sirino (2005 m). they show clear traces of glaciers dating from the lgm and their retreat phases. during the lgm, on mt. pollino (latitude 39°55’) the equilibrium line altitude was 1800 m, while on m. sirino it was 1600 m. only one rock glacier has been found on mt. pollino. it overlies the moraine of the early phases of glacial retreat, about 1750 m a.s.l; it is older than the stadial moraine covered by loess dated 15-16,000 years bp, present also in central italy. the majority of the rock glaciers were formed between 20,000 and 10,000 years bp, when the mean yearly temperatures were still 4 – 6 °c lower than the present ones; however, their geographic distribution gives rise to some important considerations. in the northern apennines, (latitude above 44°n) there are no rock glaciers, while there are some at more southerly latitudes (about 40°n), in mountains of similar elevation. the ela during the lgm reached definitely lower altitudes (1300-1550 m) than in the central and southern apennines (1500-2100 m); the absence of rock glaciers thus, cannot be due to the temperature, but to the different amount of precipitation. even now, the highest areas of the northern apennines receive precipitation of between 1500 and 2000 mm/year: the values are far higher than those of the central-southern part of the chain. it is to be assumed that the lack of rock glaciers was caused by the abundant snow precipitation which insulated the ground against frost penetration, and not by temperature differences. in the apennine chain, about 40 rock glaciers dated to the last 20,000 years have been identified. they developed in five phases, the last one between 3000 and 780±40 years bp; the rock glaciers found at lower height were formed during the lgm, but the majority formed during the late glacial phases. rock glaciers have been found mainly on massifs with a higher ela-lgm and a present lower precipitation rate; in the whole northern apennines and on the massifs with a lower ela (currently having a higher precipitation rate) rock glaciers are lacking. moreover, the rock glaciers developed mainly during the dryer periods or in places where precipitation were not very great. the geographical distribution of the rock glaciers, corresponding to the boundary of the areas with mountain permafrost, suggests that, during the final phases of the lgm period, in the late glacial and in the early holocene, there was also an altitude and latitude shift with a reduction of this boundary, following the temperature increase. from the altitude of 1570/1600 m, the boundary of discontinuous mountain permafrost rose to 2300/2500 m during the late holocene, and it is now even higher. about the time of the latitude shift, the boundary migrated northwards, from 39°55'n to 41°45'n and later to 42°07'n. parole chiave: rock glacier, appennino, ultimo massimo glaciale, olocene, paleoclima. key words: rock glacier, apennine, last glacial maximum, holocene, paleoclimate. il quaternario italian journal of quaternary sciences 1155(1), 2002, 45-52 iinnttrroodduuzziioonnee la presenza di rock glacier in appennino (fig. 1) venne segnalata per la prima volta sul massiccio gran sasso (m 2912, massima elevazione dell'appennino) da giraudi (1988). in seguito ne fu segnalata la presenza in altre zone del gran sasso, sui massicci del m. greco, della maiella e del velino, sui monti breccioso, terminillo, pollino (ghisetti & vezzani, 1990; damiani e pannuzi 1993; dramis e kotarba,1994; jaurand,1994; giraudi,1996, 1997b; 1998a,b,c,d; giraudi & frezzotti, 1997). ad eccezione, forse, di un rock glacier di dimensioni estremamente ridotte, che potrebbe essere attivo (dramis & kotarba, 1994), gli altri segnalati in letteratura e quelli rinvenuti nel corso del presente studio non mostrano segni di attività. i resti dei rock glacier sono generalmente ben conservati; si trovano infatti su montagne costituite prevalentemente da rocce carbonatiche meso-cenozoiche, soggette a carsismo: l'erosione superficiale è stata perciò limitata a causa dell'estrema riduzione del runoff. 46 giraudi nel corso del presente lavoro vengono riportati i risultati di una ricerca svolta sull'intera catena appenninica, basata su indagini fotogeologiche, di campagna e ricerche bibliografiche. lo studio dei rock glacier relitti dell’appennino è stato svolto al fine di ottenere indicazioni sull’evoluzione ambientale e paleoclimatica dell’area, in quanto la presenza di permafrost e le variazioni del suo limite di distribuzione nel corso del tempo possono servire a valutare l’evoluzione della temperatura dall’ultimo massimo glaciale (lgm) fino all’attuale. inoltre la datazione dei rock glacier permette la correlazione con eventi indicati da altri proxy-data e può servire a definire meglio le condizioni che hanno favorito lo sviluppo del permafrost. mmeettooddoollooggiiaa i rock glacier oggetto del presente lavoro sono situati su fondi vallivi e nell’ambito dei circhi glaciali, altri sono situati lungo i fianchi vallivi, alla base di accumuli fig. 1 carta schematica dell'appennino con indicazioni sulla quota della linea delle nevi nel corso dell'ultimo massimo glaciale e la distribuzione dei rock glacier. schematic map of the apennine chaine, altitude of the equilibrium line altitude during lgm, distribution of rock glaciers. legend: 1=area >1000 m a.s.l.; 2=present shore line; 3= lgm shore line. hanno dato risultati negativi. il grado di conservazione delle forme glaciali nell’appennino settentrionale è, generalmente, inferiore rispetto a quelle dell’appennino centrale. quindi non si può escludere del tutto che sia esistito qualche rock glacier, ora scomparso a causa del rimodellamento, ma una loro diffusa presenza appare improbabile. appennino centrale i maggiori massicci dell'appennino centrale (fig. 1) sono costituiti prevalentemente da rocce carbonatiche meso-cenozoiche. in questa parte della catena sono presenti anche i più alti massicci di tutto l'appennino (gran sasso, 2912 m; maiella, 2793 m; velino 2486 m; m. sibillini, 2476 m). nella porzione più elevata del massiccio del gran sasso esiste il piccolo ghiacciaio del calderone, in via di forte riduzione (smiraglia & veggetti,1992; gellatly et al., 1994), e le aree sommitali dei massicci principali sono caratterizzate da fenomeni periglaciali quali crioclastismo, soliflussioni. solo sui massicci del gran sasso e della maiella sono presenti patterned ground caratterizzati da sorted stripes, poco diffusi a partire da circa 2400 m sul primo massiccio, molto estesi a partire da circa 2600 m sul secondo (sacco, 1908; giraudi, 2001). le montagne dell'appennino centrale presentano notevoli resti glaciali, databili per lo più all’ultimo massimo glaciale (lgm) e alle sue fasi di ritiro. in base ai lavori più recenti (damiani & pannuzi, 1979; federici, 1979; jaurand,1994; giraudi & frezzotti, 1997; giraudi, 1997b; 1998a,b,c,d) il limite nivale durante l’lgm era compreso tra 1500 e 1700 m nella porzione occidentale (fig. 1) e tra 1600 e 2100 m nel resto dell'area. secondo giraudi & frezzotti (1997) la massima espansione glaciale venne raggiunta prima di 22.680±630 anni bp; il ritiro glaciale iniziò attorno a 21.000 anni bp. minori espansioni si ebbero poco prima di 15.000 anni bp e attorno a 11.000 anni bp. nell'olocene i ghiacciai sparirono del tutto; il ghiacciaio del calderone si riformò in un periodo più recente di circa 4000 anni bp (giraudi, 2000). la maggior parte dei rock glacier finora segnalati in letteratura si trova nell'appennino centrale, su versanti con esposizione verso i quadranti settentrionali; in rarissimi casi si trovano su versanti rivolti a sud, come a campo imperatore (giraudi &.frezzotti, 1997). le ricerche fotogeologiche e di campagna hanno mostrato però che nella porzione occidentale di questo tratto di catena, anche quando vi sono monti di altezza superiore a 2000 m, non sono presenti rock glacier. nel resto dell'area, i rock glacier si trovano a partire da una quota minima di 1570 m, fino a circa 2550 m. i rock glacier ed i fenomeni periglaciali attivi si trovano tutti in zone occupate dai ghiacciai nel corso dell’lgm. molti rock glacier si sviluppano a spese del detrito di origine glaciale, e spesso deformano depositi glaciali posti sulla soglia dei circhi; in vari casi il flusso non è diretto verso valle, ma verso la depressione dei circhi. le forme meno alterate e con scarsa copertura vegetale, di aspetto più fresco, si sviluppano, invece, a spese del detrito di versante. per quel che riguarda le dimensioni, i rock glacier 47i rock glacier tardo-pleistocenici ... di detrito di falda. il loro riconoscimento da parte degli autori elencati in precedenza è avvenuto su base morfologica. in generale, per quel che riguarda i rock glacier attivi vi sono diversi metodi di classificazione ancora oggetto di discussione: secondo hamilton & whalley (1995) la classificazione può essere basata su diversi parametri, alcuni possono essere misurati e quantificati, altri possono solo essere dedotti. detti parametri includono la morfologia, la dinamica, i processi di formazione, la posizione, le caratteristiche interne, il regime termico e l’età. la classificazione implica una interpretazione genetica che può essere soggettiva anche sui rock glacier attivi che possono essere studiati con vari metodi. poiché nel presente lavoro vengono presi in considerazione rock glacier inattivi, in parte modificati dall’alterazione e dell’erosione, appare difficile procedere ad una adeguata classificazione degli stessi e definirne l’origine: si provvederà quindi a fornire le informazioni disponibili senza introdurre classificazioni e distinzione di origine, tenendo conto però che la maggior parte dei rock glacier ed i più grandi tra questi, si sviluppano su detrito di falda, come segnalato da dramis & kotarba (1994). i rock glacier dell’appennino sono situati, con rare eccezioni, in aree occupate dai ghiacciai nel corso dell’lgm, in valli rivolte verso i quadranti settentrionali. le differenze di quota tra i diversi rock glacier di età analoga posti sullo stesso massiccio sono da attribuire a fattori legati alla esposizione ed alla morfologia delle valli. sui massicci ubicati a varie distanze dal mare ed a differente latitudine, le quote alle quali sono presenti i rock glacier possono essere determinate dalle caratteristiche regionali del clima e dalle variazioni latitudinali di temperatura causate dal diverso grado di insolazione. ii rroocckk ggllaacciieerr ddeellll''aappppeennnniinnoo la porzione di catena appenninica presa in considerazione è compresa tra circa 39°50' n e 44°20'n: è stata esclusa dal lavoro l'estrema porzione meridionale che, per latitudine e quota dei rilievi, non sembra adatta allo sviluppo di rock glacier nel tardo pleistocene e nell'olocene. appennino settentrionale l'appennino settentrionale (fig. 1) è formato da rilievi che possono arrivare a 2165 m di quota, litologicamente costituiti in prevalenza da arenarie e marne arenacee. nel corso dell’ultimo massimo glaciale (lgm) e delle sue fasi di ritiro, erano presenti molti ghiacciai, per lo più in valli rivolte verso i quadranti settentrionali: gli apparati morenici frontali di tali ghiacciai sono stati rinvenuti fino a circa 700 m di quota. gli studi condotti da vari autori (federici, 1981; gruppo ricerca geomorfologia,1982; federici & tellini, 1983; braschi et al., 1985; jaurand, 1994) indicano che durante l’lgm il limite delle nevi (ela) era a quote comprese tra 1300 e 1550 m. nessun rock glacier risulta segnalato in bibliografia. anche le ricerche fotogeologiche e di campagna più estesi si trovano sui massicci della maiella e del velino e raggiungono lunghezze di circa 1 km. appennino meridionale i monti più elevati dell'appennino meridionale sono il pollino (2267 m) ed il sirino (2005 m), e conservano evidenti tracce dei ghiacciai dell’lgm e delle fasi di ritiro. durante l’lgm, sul m. pollino (latitudine 39°55') l’ela era a 1800 m, mentre sul m. sirino era a 1600 m (palmentola & acquafredda, 1983; palmentola et al., 1990; jaurand, 1994; giraudi, 1998d). un solo rock glacier è stato identificato sul m. pollino in un versante esposto a nord. ddaattaazziioonnee ddeeii rroocckk ggllaacciieerr la datazione delle fasi di sviluppo dei rock glacier è stata ottenuta sia in base ai rapporti tra questi e le morene dell’lgm e stadiali di età nota, sia attraverso lo studio dei depositi e dei suoli che li coprono e si riferiscono all’appennino centrale e meridionale. su alcuni cordoni di rock glacier sono stati eseguiti piccoli scavi o, specialmente nelle depressioni riempite da materiali fini, sondaggi mediante trivella a mano profondi fino a 4 m: sono stati in tal modo rinvenuti sedimenti eolici, livelli di tephra, suoli sepolti, sedimenti lacustri. lo studio di tali depositi, che, non essendo deformati debbono essere stati messi in posto quando il rock glacier non era più dinamicamente attivo, ha permesso la datazione delle fasi di sviluppo dei rock glacier. a proposito del significato delle datazioni di seguito esposte, occorre evidenziare che esse potrebbero indicare solo la fine dell’attività dinamica dei rock glacier e non la scomparsa effettiva del permafrost; questo potrebbe essere rimasto presente tra il detrito per periodi di tempo attualmente non determinabili. i fase i rock glacier di questa fase, sono situati alle quote inferiori (i più bassi a 1570÷1600m); interessano le morene formatesi nelle prime fasi di ritiro dei ghiacciai dell’lgm. l'inizio del ritiro glaciale è databile a circa 21.000 anni bp giraudi & frezzotti (1997). altri rock glacier sono posti a quote leggermente più elevate (da 1650 a 1750/1800) ma sempre a ridosso delle morene delle prime fasi di ritiro. nelle depressioni presenti su alcuni di questi è stato rinvenuto un loess ricco in quarzo databile a 15÷16.000 anni fa (frezzotti & giraudi,1991; giraudi, 1998b) che copre anche le morene dell’lgm, ma non quelle tardiglaciali (giraudi, 1997a). lo sviluppo di questi rock glacier può essere durato al massimo 5000÷6000 anni. ii fase i rock glacier di questa fase, i più numerosi, possono essere contemporanei o successivi ad alcune morene tardiglaciali; si possono trovare a varie quote, al di sopra di 1750/1800 m, sia in alcuni circhi glaciali, sia al di fuori. in alcune depressioni, i sondaggi a mano condotti nell’ambito del presente studio hanno portato alla individuazione di un tephra, molto diffuso nell'area, e di un andosuolo su esso sviluppato. il tephra è attribuito, in base alla sua composizione mineralogica, all'eruzione del tufo giallo napoletano (frezzotti & narcisi, 1996). l'eruzione avvenne circa 12.300±300 anni bp (alessio et al., 1973) nei campi flegrei (campania). la ii fase è quindi più recente delle morene formate da ghiacciai con un ela superiore di 200÷280 m rispetto a quella dell’lgm, messe in posto prima della sedimentazione del loess ricco di quarzo, e più antica di circa 12.300 anni bp. lo sviluppo dei rock glacier di tale fase può essere durato 4000-5000 anni. iii fase i rock glacier di questa fase, sono collocati nei circhi glaciali e nelle alte valli, al di sopra dei 1900 m. sono molto meno alterati e vegetati di quelli della ii fase, non sono più coperti dal tephra e dall'andosuolo, e i loro depositi basali possono coprire o essere incassati nelle morene coperte da questi. in una depressione presente su un rock glacier di questa fase è stato trovato un deposito lacustre, datato, alla base, 8035±140 anni (data convenzionale) bp col metodo del radiocarbonio (giraudi & frezzotti, 1997). lo sviluppo dei rock glacier deve essere successivo al tephra databile a circa 12.000 anni bp; si ritiene, quindi, che tale fase di sviluppo coincida con il younger dryas. l'attività di tali rock glacier può essere durata circa 3000 anni. almeno un rock glacier di questa fase coinvolge solo morene databili a circa 14.000 anni fa, ma non è coperto dal tephra o dall'andosuolo: potrebbe essere un rock glacier sviluppatosi nella ii fase, ma rimasto attivo anche nel corso della terza, quindi per un periodo di tempo valutabile a 6000 anni. iv fase i rock glacier di questa fase si trovano a quote superiori a circa 2000 m, nelle alte valli e nei circhi glaciali. non vi sono elementi stratigrafici chiari per distinguerli da quelli della iii fase, ma sono nettamente meno vegetati, perché il suolo superficiale è molto pietroso, e si trovano a quote maggiori. scavando nel deposito, si rinvengono le tracce di un suolo limoso, scomparso dalla superficie, che è stato datato col metodo radiocarbonio ams ed ha fornito un'età convenzionale di 3180±40 anni bp (beta –145529). il suolo è formato in parte da minerali vulcanici, ma non è un andosuolo come quello sviluppatosi sul tephra del tufo giallo napoletano. i minerali provengono da un livello di tephra, non ancora adeguatamente studiato in quanto sottile, mal conservato e fortemente alterato. tale tephra viene chiamato "duchessa", dal nome della montagna sul quale è stato rinvenuto e datato per la prima volta, e copre suoli datati 4390±50 (beta 117017), 4220±80 (beta 106450) e 4020±70 (beta 111004) anni bp. la iv fase è quindi più antica di circa 4000 anni bp, e dovrebbe essere più recente del younger dryas, ma non è chiaro quale sia la sua età reale all'interno di tale lungo intervallo di tempo. non si può escludere che questi rock glacier (o alcuni di essi) si siano sviluppati nella fase precedente ma siano rimasti attivi fino a circa 4000 anni bp. il loro sviluppo potrebbe essere durato 48 giraudi 49i rock glacier tardo-pleistocenici ... quindi 6000-7000 anni bp. v fase i rock glacier di questa fase sono rarissimi, molto piccoli, e si rinvengono a quote superiori a 2270 m: giacciono nelle parte superiori di circhi glaciali, esposti a n e ne, dominati da pareti molto ripide, in zone dove la copertura vegetale è quasi assente. scavando nel deposito, si rinvengono le tracce di un suolo limoso senza minerali vulcanici, scomparso dalla superficie. uno di questi suoli, datato col metodo radiocarbonio-ams ha fornito una età di 780±40 anni bp (beta-145530). lo sviluppo di tale fase è quindi databile tra circa 3180±40 e 780±40 anni bp, in quanto neanche i detriti sui quali si sviluppano sono coperti dal suolo su vulcanico che ha fornito la più antica delle due date (vedasi paragrafo precedente). lo sviluppo dei rock glacier di questa fase può essere durato al massimo attorno ai 2000 anni. mancando ancora studi dettagliati, non è possibile stabilire se il rock glacier che secondo dramis & kotarba (1994) potrebbe essere attivo, sia da attribuire alla v fase o si sia sviluppato in seguito. lo schema cronologico per la datazione delle cinque fasi di sviluppo dei rock glacier è rappresentato in fig. 2. ddiissccuussssiioonnee la maggior parte dei rock glacier si formò tra 20.000 e 10.000 anni bp, quando le temperature erano ancora nettamente inferiori alle attuali (giraudi & frezzotti, 1997), tuttavia la loro distribuzione areale suggerisce alcune importanti considerazioni. nell'appennino settentrionale, (latitudine superiore a 44°n) non sono stati rinvenuti rock glacier, presenti invece a latitudini più meridionali (circa 40°), su montagne di elevazione paragonabile. l’ela durante l’lgm era a quote nettamente inferiori (1300÷1550 m) rispetto a quella del resto dell'appennino (1550÷2100 m). poiché nell’appennino settentrionale, a causa della vicinanza della calotta alpina e del gradiente latitudinale, la temperatura doveva essere un po’ minore rispetto a quella dell’appennino centro-meridionale, l'assenza dei rock glacier deve essere imputata alla diversa quantità di precipitazioni. anche attualmente, le aree più elevate dell'appennino settentrionale ricevono precipitazioni superiori a 1500 mm/anno e in alcuni casi a 2000 mm/anno (ministero dei lavori pubblici, 1968): i valori sono molto più elevati rispetto a quelli della maggior parte della porzione centro-meridionale della catena. si ipotizza che l'assenza di rock glacier sia stata causata dalle abbondanti precipitazioni nevose che proteggevafig. 2 distribuzione, inquadramento cronologico, altitudine e latitudine dei rock glacier dell'appennino. distribution, chronological framework, altitude and latitude of the apennine rock glaciers. 50 giraudi no il suolo dalla penetrazione del gelo. nell'appennino centrale, la porzione occidentale risulta priva di rock glacier; i resti glaciali indicano che in tale zona l’ela durante l’lgm era più bassa (1550÷1700 m) rispetto al resto (1600÷2100 m). non si possono invocare differenze di temperatura dovute alla latitudine. per quel che riguarda la possibile influenza del mare sul clima locale, si può ipotizzare che il mare tirreno mitigasse le temperature della porzione occidentale, mentre il mare adriatico, che in periodo glaciale aveva un’estensione molto più ridotta dell’attuale (fig. 1) non poteva fare altrettanto sulla porzione orientale della catena. questa doveva risultare, quindi, più fredda. la bassa quota di ela nella porzione occidentale, deve essere stata causata dalle maggiori precipitazioni. anche attualmente (ministero dei lavori pubblici, 1968) nelle zone più elevate della porzione occidentale le precipitazioni (> di 1500 e per alcune zone > di 2000 mm/anno) superano abbondantemente quelle del resto dell'appennino centrale (< 1500 mm/anno). anche in questo caso l'assenza di rock glacier potrebbe essere stata causata dalle abbondanti precipitazioni nevose che proteggevano il suolo dalla penetrazione del gelo. nell'appennino meridionale, si nota che non vi sono rock glacier nel massiccio (m. sirino) che aveva l’ela più basso (1600 m) durante l’lgm e che anche attualmente (ministero dei lavori pubblici, 1968) ha una elevata piovosità (>2000 mm/anno). un rock glacier è presente invece sul m. pollino, il più meridionale dei due massicci, che aveva un ela durante l’lgm a 1800 m e che attualmente riceve una quantità di precipitazioni <1500 mm/anno (ministero dei lavori pubblici, 1968):. la quota minima alla quale si trovano i rock glacier nell'appennino centrale è inferiore di 80 m rispetto a quella dell'appennino meridionale. anche se dal punto di vista statistico questo dato potrebbe non essere significativo, non si può escludere che tale differenza possa essere dovuta al gradiente latitudinale di temperatura, visto che in entrambe le zone i rock glacier giacciono prevalentemente su versanti esposti verso i quadranti settentrionali. considerando l'importanza dell'entità delle precipitazioni nella distribuzione geografica dei rock glacier, si è provato a vedere se l'influenza dell’umidità è stata importante nel corso di tutto il periodo di tempo esaminato. fig. 3 confronto tra le oscillazioni di livello del lago del fucino e le fasi di sviluppo dei rock glacier. comparison between the lake fucino oscillations and the age of the phases of rock glaciers development. fig. 4 confronto tra lo sviluppo dei rock glacier e l'estensione dei ghiacciai dell'appennino. comparison between rock glaciers development and the apennine glacier extent. per valutare le variazioni di umidità nell'appennino centrale è stata presa in considerazione la curva delle oscillazioni di livello del lago fucino, posto al centro dell'area in esame. il lago fucino, bonificato nel xix secolo, era un lago senza emissario, soggetto a forti variazioni di livello dovute a cause climatiche (giraudi, 1998e). si assume che il bilancio idrologico del lago sia 51i rock glacier tardo-pleistocenici ... indicativo delle variazioni di umidità nella zona. in fig. 3 è riportata, insieme alla curva delle oscillazioni di livello del lago, la distribuzione temporale delle fasi di sviluppo dei rock glacier. e' possibile dedurre che: le prime tre fasi si verificano in corrispondenza di periodi di basso livello lacustre, quindi di scarsa umidità; la iv fase, di durata mal determinabile, potrebbe essere contemporanea sia a periodi di livello del lago basso che medio-alto; la v fase corrisponde ad un periodo di forti oscillazioni di breve durata: anche in questo caso la risoluzione temporale non è abbastanza dettagliata da permettere una correlazione più precisa; un dato solo è certo, che questa fase è precedente al periodo di massima umidità, corrispondente alla piccola età glaciale. nel complesso si può assumere che le varie fasi di sviluppo dei rock glacier siano identificabili con i periodi più aridi degli ultimi 20.000 anni o, almeno, non coincidano con i più umidi. il numero di rock glacier per ciascuno di tali periodi è invece funzione della temperatura, essendo molto più abbondanti nel corso dell’lgm e del tardiglaciale. altre informazioni derivano dal contronto tra le fasi di sviluppo dei rock glacier e le fasi glaciali. schematizzando (fig. 4) le modifiche dell'estensione dei ghiacciai nell'appennino centrale e paragonandole al numero approssimato di rock glacier, si nota che il numero tendeva a salire mentre i ghiacciai si riducevano. al contrario, nell'olocene, vi erano rock glacier quando i ghiacciai erano assenti: il loro numero si ridusse però quando il ghiacciaio del calderone si riformò (a partire da circa 4000 anni bp) e si espanse. potrebbe esserci una contrapposizione tra fasi di sviluppo dei ghiacciai e dei rock glacier. ccoonncclluussiioonnee nella catena appenninica sono presenti circa 40 rock glacier databili agli ultimi 20.000 anni, sviluppatisi in cinque diverse fasi, l'ultima delle quali tra circa 3000 e 780±40 anni bp; nel corso dell’lgm si formarono i rock glacier alle quote inferiori, il maggiore sviluppo si ebbe nelle fasi tardiglaciali. i rock glacier si sono sviluppati maggiormente su quei massicci caratterizzati da un ela durante l’lgm non molto bassa: l'intero appennino settentrionale ed i massicci che avevano un ela basso, e che attualmente sono soggetti a precipitazioni molto più elevate, ne sono risultati privi. inoltre i rock glacier si sviluppavano per lo più nel corso delle fasi climatiche aride o non molto umide. dalla distribuzione areale dei rock glacier si deduce che, durante le fasi finali dell’lgm, nel tardiglaciale e nell'olocene iniziale, c'è stata, oltre che una migrazione verticale, anche uno spostamento verso nord del limite della loro area di distribuzione: quindi il limite del permafrost montano è passato da 39°55'n a 41°45'n e poi a 42°07'n. in seguito ci fu soltanto una migrazione verticale, in quanto nel tardo olocene i rock glacier hanno potuto svilupparsi solo sulle parti sommitali dei due massicci più elevati. rreeffeerreenncceess alessio m., bella f., improta s., cortesi c. & turi b. (1973) university of rome carbon -14 dates, ix. radiocarbon, 15, 165-178. boenzi f. & palmentola g. (1971) tracce della glaciazione würmiana sul massiccio del pollino al confine calabro-lucano. boll. soc. geol. it., 90, 139-150. braschi s., del freo p. & trevisan l. (1986) ricostruzione degli antichi ghiacciai sulle alpi apuane. atti società toscana di scienze naturali, ser. a, 93, 203-219. damiani a.v. & pannuzi l. (1979) la glaciazione würmiana nell'appennino laziale-abruzzese (5) : i ghiacciai dei m. simbruini (campo ceraso, valle monazzone, fiumata, valle granara) e considerazioni di tettonica recente. mem. descr. carta geol. d'it., 38, 215-250. damiani a.v. & pannuzi l. (1993) la glaciazione pleistocenica nell'appennino laziale-abruzzese. nota vi: i ghiacciai del gruppo del m. greco e considerazioni di tettonica recente. boll. serv. geol. d'it., cx, 111-158. dramis f. & kotarba a. (1994) geomorphological evidences of high mountain permafrost in central apennine. geogr. fis. din. quat., 17, 29-36. federici p.r. (1979) una ipotesi di cronologia glaciale wurmiana, tardo e post-wurmiana nell'appennino centrale. geogr.fis.din.quat.,2, 196-202. federici p.r. (1981) the quaternary glaciation on the seaward side of the apuan alps. rivista geografica italiana, 88 (2), 183-199. federici p.r. & tellini c. (1983) la geomorfologia dell'alta val parma (appennino settentrionale). rivista geografica italiana, 90 (3-4), 393-428. fiucci a., gigante b., rossi c., smiraglia c. & veggetti o. (1997) the calderone glacier (gran sasso d'italia). determination of ice thickness and bedrock morphology by means of radio-echo sounding. geogr. fis. dinam. quat., 2200, 305-308. frezzotti m. & giraudi c. (1990) late glacial and holocene aeolian deposits and features near roccaraso (abruzzo, central italy). quaternary international, 5, 89-95. frezzotti m. & narcisi b. (1996). late quaternary tephra-derived paleosols in central italy's carbonate apennine range: stratigraphical and paleoclimatological implications. quaternary international 3436, 147-153. gellatly a.f., smiraglia c., grove j.m. and latham r. (1994). recent variations of ghiacciaio del calderone, abruzzi, italy. journal of glaciology. 4400, 486-490. ghisetti f. and vezzani l. (1990). carta geologica del gran sasso d'italia (da vado di corno al passo delle capannelle). cartografia s.el.ca., firenze. giraudi c. (1988) segnalazione di scarpate di faglia post-glaciali nel massiccio del gran sasso (abruzzo): implicazioni tettoniche, rapporti tra tettonica recente e morfologia, paleosismicità. mem. soc. geol.it., 41,627-635. giraudi c. (1996) l'impronta del "younger dryas" e degli "heinrich events" nell'evoluzione climatica e ambientale dell'italia centrale. il quaternario, 9(2), 533-540. giraudi c. (1997a) dating and correlation of glacial deposits using tephra layers and loess: the example of m. matese (campania-molise) southern italy. studia geomorphologica carpathobalcanica. xxxi, 45-56. giraudi c. (1997b) prima segnalazione dell'apparato glaciale del m. breccioso (val roveto abruzzo): un contributo all'inquadramento cronologico delle fasi glaciali tardo-pleistoceniche. il quaternario, 10(2), 201-206. giraudi c. (1998a) il glacialismo tardo-pleistocenico del massiccio del terminillo (lazio appennino centrale). il quaternario, 11 (1), 121-125. giraudi c. (1998b) the late quaternary geologic evolution of campo felice (abruzzo central italy). giornale di geologia, sez. 3, 60, 67-82. giraudi c. (1998c) nuovi dati sul glacialismo della montagna della maiella (abruzzo-italia centrale). il quaternario, 11(2), 265-271. giraudi c. (1998d) la deglaciazione tardopleistocenica sui m. sirino e pollino (basilicata, calabria-italia meridionale). il quaternario, 11(2), 247-254. giraudi c. (1998e) late pleistocene and holocene lake level variations in fucino lake (abruzzo central italy) inferred from geological, archaeological and historical data. esf workshop "palaeohydrology as reflected in lake-level changes as climatic evidence for holocene times". palaoklimaforschungpalaeoclimate research, 2255, 1-18, gustav fisher verlag ed. giraudi c. (2000) le oscillazioni oloceniche del ghiacciaio del calderone, gran sasso d'italia (abruzzo italia). il quaternario, 13(1/2), 31-38. giraudi c. (in press) segnalazione di suoli a strisce parallele (sorted stripes) sul gran sasso d'italia (abruzzo). il quaternario. giraudi c. & frezzotti m. (1997) late pleistocene glacial events in the central apennine, italy. quaternary research, 48 (3),280-290. gruppo ricerca geomorfologia c.n.r. (1982) geomorfologia del territorio di febbio tra il m. cusna e il f. secchia (appennino emiliano). geogr.fis. din. quat., 5, 285-360. hamilton s.j. & whalley w.b. (1995) – rock glacier nomenclature: a reassesment. geomorphology, 14, 73-80. jaurand e. (1994) les heritages glaciaire de l'apennin. thèse pour le doctorat dès lettres de l'université de paris i panthéon-sorbonne. 600 pp. ministero dei lavori pubblici (1968) – carta della precipitazione media annua in italia per il trentennio 1921-1950. consiglio superiore servizio idrografico, pubbl. n. 24 (14). palmentola g. & acquafredda p. (1983) gli effetti dei ghiacciai quaternari sulla montagna del matese, al confine molisano-campano. geogr. fis. dinam. quat., 66, 117-130. palmentola g., acquafredda p. & fiore s. (1990) a new correlation of the glacial moraines in the southern appennines, italy. geomorphology, 3, 18. sacco f. (1908) glacialismo ed erosione nella majella. atti soc. it. sc. nat., 4477, 269-280. smiraglia c. & veggetti 0. (1992) recenti osservazioni sul ghiacciaio del calderone (gran sasso d'italiaabruzzo). boll. soc. geogr. it., ser.xi, 44, 269-302. 52 ms. ricevuto il 6 novembre 2001 testo definitivo ricevuto il 19 marzo 2002 ms. received: november 6, 2001 final text received: march 19, 2002 giraudi imp. bini & ddeeffiinniizziioonnee ddii aallccuunnii tteerrmmiinnii iinn uussoo nneellllaa ccaarrttooggrraaffiiaa ddeeii ddeeppoossiittii qquuaatteerrnnaarrii ccoonnttiinneennttaallii iinn aammbbiittoo aallppiinnoo aallffrreeddoo bbiinnii11,, aannddrreeaa bboorrssaattoo22,, ffrraanncceessccoo ccaarrrraarroo33,, aallbbeerrttoo ccaarrttoonn44,, ddaanniieellee ccoorrbbaarrii55,, mmaauurriizziioo ccuuccaattoo66,, ggiioovvaannnnii mmoonneeggaattoo77,,88,, && ggiioovvaannnnii bbaattttiissttaa ppeelllleeggrriinnii88 1dipartimento di scienze della terra, università degli studi, via mangiagalli 14, 20133 milano; 2museo tridentino di scienze naturali, via calepina 14, 38100 trento; 3dipartimento di scienze della terra, università degli studi via valperga caluso 35, 10125 torino; 4dipartimento di scienze della terra, università degli studi, via ferrata 1, 27100 pavia; 5ufficio attività generali e di conoscenza del territorio, direzione generale territorio ed urbanistica regione lombardia. via sassetti 32/2, 20124 milano; 6c/o l'ufficio geologia e prove materiali, via val d'ega, n. 48, 39053 cardano (bz); 7dipartimento di georisorse e territorio, università degli studi, via cotonificio, 114, 33100 udine; 8dipartimento di geologia, paleontologia e geofisica, università degli studi, via giotto, 1, 35137 padova. riassunto: bini a. et al., definizione di alcuni termini in uso nella cartografia dei depositi quaternari continentali in ambito alpino. (it issn 0394 – 3356, 2004). in questi anni nuovi approcci metodologici di rilevamento e cartografia dei depositi quaternari continentali hanno consentito l’abbandono del “modello classico” introdotto da penck e brückner (1909) basato sulle quattro glaciazioni, a favore di un approccio che utilizza unità stratigrafiche delimitate da discontinuità e definite secondo ambiti bacinali (idrografici e/o glaciali), inserite in una scala cronologica relativa (unità allostratigrafiche e unità stratigrafiche a limiti inconformi). in questa nota, frutto del confronto tra diversi autori, vengono proposte le definizioni dei termini utilizzati in ambito alpino secondo tale approccio, al fine di chiarirne il significato e precisarne l’utilizzo. in particolare vengono discussi i termini: lgm (last glacial maximum), postglaciale e pre–lgm. il termine lgm indica l'ultimo massimo glaciale locale, senza riferimento alcuno ad unità cronologiche o stratigrafiche. col termine postglaciale si vuole indicare l’insieme di eventi che si succedono a partire dal termine dell’ultima massima espansione glaciale locale, mentre pre-lgm indica l’insieme degli eventi che la precedono. contestualmente alla spiegazione della terminologia introdotta, vengono anche brevemente affrontate le problematiche che ne derivano relativamente alla classificazione di depositi, delle unità ed alle conseguenti ricadute cartografiche, proponendo alcune possibili soluzioni. abstract: bini a. et al., definition of some terms used in the cartography of alpine continental quaternary deposits. (it issn 0394 – 3356, 2004). in the past decade a new approach to cartography and mapping of quaternary continental deposits allowed the abandonment of the now obsolete "classical model" by penck & brückner (1909), which was based on four major glaciations. the new approach utilizes stratigraphic units, which are bounded by discontinuities and defined by following glacial and/or hydrographic basins, framed within a relative chronological scale (allostratigraphic units and unconformity-bounded stratigraphic units). the present paper, which synthesizes different approaches to quaternary continental stratigraphy, proposes a definition of the terminology used in the alpine area, in order to make clear the significance of each term, and assess its proper use. the terms llaasstt ggllaacciiaall mmaaxxiimmuumm ((llggmm)),, ppoosstt--ggllaacciiaall, and pprree––llggmm are here discussed in detail. the term llggmm indicates the last local glacial maximum, without any reference to stratigraphic and chronostratigraphic units. the term ppoosstt--ggllaacciiaall is used to indicate the events which followed the last local glacial expansion. the term pprree––llggmm indicates the events that preceded the last local glacial maximum. furthermore, we here discuss some of the problems of classification that arise following the use of the new terminology, and suggest possible cartographic solutions. parole chiave: lgm, pre-lgm, postglaciale, ubiquitario, indifferenziato, indistinto, keywords: last glacial maximum, pre–lgm, post-glacial, ubiquitary, undifferentiated, indistinct. il quaternario italian journal of quaternary sciences 1177(1), 2004, 75-82 iinnttrroodduuzziioonnee gli studi condotti in questi anni in ambito alpino italiano hanno visto diverse scuole di pensiero affrontare in modo originale le problematiche di rilevamento e cartografia dei depositi quaternari continentali. il confronto che sta avvenendo attualmente fra queste diverse scuole, anche all’interno del progetto carg, mostra come il quadro d’insieme che ne deriva sia sostanzialmente congruente, almeno per quanto riguarda il significato dei corpi cartografati, la cronologia dell’evoluzione quaternaria, e le ricostruzioni paleoambientali che ne conseguono. comune a tutti i differenti approcci è l’abbandono del “modello classico” delle glaciazioni alpine (penck e brückner, 1909), in accordo con quanto sancito nel final report dell’igcp 24 “quaternary glaciations in the northern hemisphere” (s̆ibrava, bowen e richmond, 1986), a favore di un approccio che utilizza unità stratigrafiche inserite in una scala cronologica relativa, secondo i normali principi della geologia. si cartografano cioè corpi sedimentari e non “glaciazioni” o “interglaciali” (ossia eventi climatici), quindi corpi che non vengono più definiti secondo criteri climatici o morfologici, ma sulla base dei caratteri interni e delle discontinuità che li delimitano. a tal fine sono state utilizzate unità stratigrafiche definite fondamentalmente secondo ambiti bacinali 76 a. bini et al. (idrografici e/o glaciali), caratterizzate sulla base delle discontinuità che le delimitano superiormente ed inferiormente, ed ulteriormente dettagliate nelle facies sedimentarie che le compongono (bini et al., 1989; bini, 1997; bini e pellegrini 1998; bini et al., 2001). le unità di riferimento per tale lavoro sono state inizialmente le uunniittàà aalllloossttrraattiiggrraaffiicchhee e, più recentemente, le uunniittàà aa lliimmiittii iinnccoonnffoorrmmii (ubsu = unconformity-bounded stratigraphic units), come raccomandato dal servizio geologico nazionale (2001) in considerazione che solo queste ultime risultano formalizzate nella international stratigraphic guide (1994). appare opportuno precisare, tuttavia, che le ubsu non corrispondono in maniera soddisfacente alle caratteristiche delle unità del quaternario continentale in quanto le discontinuità che delimitano queste ultime: 1. non corrispondono necessariamente ad unconformities; 2. hanno solo raramente estensione regionale, come invece è previsto “preferibilmente” per le ubsu; 3. non sono quasi mai “visibili”, come presunto per le ubsu, ma sono più frequentemente solo “tracciabili” per interpolazione. da vari momenti di confronto e scambio di esperienze fra le diverse scuole è emersa l’esigenza comune di precisare il significato di alcuni termini di uso corrente nei vari gruppi che si occupano di rilevamento dei depositi quaternari continentali in ambito alpino; nello stesso tempo la presente nota ha lo scopo di fare conoscere tali termini ed il loro corretto utilizzo anche a quanti non si occupano direttamente di tali problematiche. 11.. llaasstt ggllaacciiaall mmaaxxiimmuumm in senso generale il termine llaasstt ggllaacciiaall mmaaxxiimmuumm (acronimo llggmm) rappresenta l'ultimo massimo glaciale locale. si vuole indicare in questo modo l’ultima grande espansione glaciale llooccaallee, senza riferimento alcuno ad unità cronologiche o stratigrafiche. il termine llooccaallee fa riferimento, in prima approssimazione, a singoli bacini i cui ghiacciai non erano coalescenti e, in seconda approssimazione, all'intero ambito alpino, considerato come locale rispetto al resto dei rilievi europei ed extraeuropei. lo lgm nnoonn iinnddiiccaa ssoollaammeennttee ll''aaccmmee ggllaa-cciiaallee mmaa ll’’iinntteerroo eevveennttoo, comprendendo quindi sia le fasi di avanzata che quelle di ritiro del ghiacciaio (“tardiglaciale” auctorum). dalla definizione sopraesposta derivano alcune considerazioni: a) il termine lgm non va inteso come sinonimo dell’ultima glaciazione a livello globale né deve essere utilizzato come sinonimo di würm, o würm iii; b) lo lgm, come del resto ogni altra glaciazione, non è un evento isocrono, ma la sua durata temporale si riduce progressivamente spostandosi dalle zone più interne della catena alpina agli anfiteatri. 11..11.. ddeeppoossiittii eedd uunniittàà rriiffeerriibbiillii aalllloo llggmm sono essenzialmente riferibili allo lgm i soli depositi glacigenici. nel tracciamento del limite dello lgm devono essere presi in considerazione solamente i depositi glaciali o, in assenza di questi, depositi di contatto glaciale e proglaciali le cui geometrie descrivono il limite della massa glaciale dello lgm (vedi figura 1). la cartografia dei depositi associati allo lgm deve essere impostata secondo una logica di bacini (glaciali e/o idrografici) di pertinenza degli agenti deposizionali che concorrono alla formazione dei depositi, definendo quindi specifiche unità nei vari bacini. in bacini differenti i depositi glaciali legati a tale evento climatico non sono necessariamente sincroni né automaticamente correlabili, da qui la necessità di introdurre il concetto di “massimo glaciale locale”. tale affermazione è valida non solo nel caso di bacini limitrofi, ma si estende all’intero ambito alpino. la contemporaneità degli eventi e la correlabilità dei depositi tra bacini differenti vanno dimostrate mediante l’utilizzo di datazioni o mediante il tracciamento laterale dei limiti nel caso di corpi fra loro in continuità. le unità cartografiche che comprendono i depositi glaciali associati allo lgm hanno il rango di sintema/alloformazione. la sigla lgm non deve essere utilizzata per denominare unità; può invece servire per caratterizzarne la descrizione (ad es. nelle note illustrative, sintema di xxx – rappresenta lo lgm). per evitare la possibilità di accorpamenti arbitrari fra aree e bacini differenti, è preferibile che tale caratterizzazione non venga riportata nelle legende delle carte ma solamente all’interno delle note illustrative. la rappresentazione cartografica delle unità riferibili allo lgm dovrebbe privilegiare l’utilizzo di una stessa tonalità di colore estesa su tutti i bacini; le sue suddivisioni nei singoli bacini, ed eventualmente all’interno di questi (es. allomembri/subsintemi), dovrebbero essere evidenziate mediante sigle. le differenze interne, date dalle variazioni laterali di facies, invece andranno rese mediante appositi soprassegni (vedi figura 1). tale scelta di resa cartografica non è vincolante: possono, ad esempio, essere utilizzati colori leggermente diversi per i diversi bacini oppure, colori uguali ma resi con retinature differenti nei diversi bacini, anche per sottolineare la non provata sincronicità delle unità. all'interno delle unità lgm si utilizzano sottounità (subsintemi/allomembri) per definire i depositi glacigenici delle valli secondarie durante la fase di deglaciazione (“tardiglaciale” auctorum). 11..22.. ccoonnssiiddeerraazziioonnii ee pprroobblleemmaattiicchhee iinn ccoorrssoo ddii ddiissccuuss-ssiioonnee il termine llaasstt ggllaacciiaall mmaaxxiimmuumm è diventato di uso corrente da parte di quanti si occupano dello studio del quaternario continentale a livello internazionale (crowley & north, 1991); viene però inteso con diverse accezioni e sfumature1. in considerazione di questo fatto, si è preferito mantenere il termine nella sua dizione inglese, andando però a precisare il significato che tale termine assume nel contesto della ricerca scientifica condotta in ambito alpino italiano. 1il termine lgm nasce, con significato climatico, dalla stratigrafia continentale del nord america, per indicare la massima avanzata della glaciazione wisconsin (würm) nella zona intorno ai grandi laghi, anche se poi viene normalmente utilizzato nella stratigrafia delle carote di ghiaccio ed in quasi tutti i lavori che si occupano dell’ultimo evento glaciale. lgm sensu stricto è stato cronologicamente definito da crowley & north (1991) in base a isotopi e carbonati in oceano e ghiaccio come un intervallo di circa 1500-2000 anni intorno a 18 mila 14c bp e calibrato verso 21 mila cal bp. 77definizione di alcuni termini ... f ig . 1 s e zi o n e g e o lo g ic a i d e a liz za ta c h e e se m p lif ic a i r a p p o rt i st ra tig ra fic i fr a u n ità q u a te rn a ri e i n a re a d i a n fit e a tr o ; si i m m a g in a c h e l a s e zi o n e s ia t ra cc ia ta p e rp e n d ic o la rm e n te a i co rd o n i m o re n ic i t e rm in a li "a " e " b ". i s in te m i x x x e y y y (1 e 2 r is p e tt iv a m e n te ) so n o c o st itu iti d a d e p o si ti le g a ti a d u e d is tin te g la ci a zi o n i; l‘u n ità p o st g la ci a le ( 3 ) co m p re n d e i d e p o si ti su cc e ss iv i a ll’ u ltim o e ve n to g la ci a le . i d e p o si ti d e l s in te m a y y y so n o a ss o ci a ti a ll’ u lti m o e ve n to g la ci a le d e ll’ a re a ( l g m ); t a li d e p o si ti si s o vr a p p o n g o n o s o lo p a rz ia lm e n te a q u e lli d e l s in te m a x x x , se d im e n ta ti d a u n p re ce d e n te e ve n to g la ci a le ( p re -l g m ). n e lla p o rz io n e i n te rn a d e ll’ a n fit e a tr o i d e p o si ti a llu vi o n a li d e ll’ u n ità p o st g la ci a le e ro d o n o e r ic o p ro n o i d e p o si ti flu vi o g la ci a li ri fe ri b ili a llo l g m , m e n tr e n e lla p o rz io n e e st e rn a s o n o q u e st i u lti m i a d e ro d e re e r ic o p ri re i d e p o si ti flu vi o g la ci a li co rr e la ti co l p re ce d e n te e ve n to g la ci a le . i lim iti c h e d e fin is co n o q u e st e u n ità s o n o d is co n tin u ità s ig n ifi ca tiv e ; a ll’ in te rn o d i o g n i si n te m a , ta li lim iti so n o d ia cr o n i. il lim ite m a ss im o r a g g iu n to d a l g h ia cc ia io n e ll’ u lti m a g la ci a zi o n e ( l im ite l g m ) è m a te ri a liz za to d a l m a rg in e i n te rn o d e lla m o re n a t e rm in a le b . in a ss e n za d i ta le c o rd o n e , il lim ite d e l g h ia cc ia io p u ò e ss e re t ra cc ia to , co n m a g g io r g ra d o d i a p p ro ss im a zi o n e , a p a rt ir e d a lla g e o m e tr ia d e i d e p o si ti d i co n ta tt o g la ci a le e /o p ro g la ci a li. l a d is tin zi o n e f ra l e d iv e rs e f a ci e s d e i d e p o si ti in u n d a to si n te m a è r e sa g ra fic a m e n te m e d ia n te u n a p p o si to s o vr a ss e g n o , m e n tr e c o lo re e s ig la d e l s in te m a r im a n g o n o in va ri a ti. id e a liz e d g e o lo g ic a l se ct io n p e rp e n d ic u la r to t h e t e rm in a l m o ra in e s "a " a n d " b " sy n th e si zi n g t h e s tr a tig ra p h ic r e la tio n sh ip b e tw e e n q u a te rn a ry u n its i n t h e a m p h ith e a tr e . s yn th e m e s x x x a n d y y y (1 a n d 2 r e sp e ct iv e ly ) a re m a d e u p o f tw o d iff e re n t g la ci a tio n d e p o si ts ; th e p o st -g la ci a l u n it co m p ri se s d e p o si ts y o u n g e r th a n t h e l a st g la ci a l m a xi m u m ( l g m ); t h e s yn th e m e y y y d e p o si ts a re r e la te d t o t h e lo ca l l g m , a n d o ve rl ie o n ly p a rt ia lly t h e s yn th e m e x x x d e p o si ts , w h ic h a re r e la te d t o a n o ld e r g la ci a l e ve n t (p re -l g m ). in t h e in n e r p a rt o f th e a m p h ith e a tr e t h e p o st -g la ci a l u n it a llu vi a l d e p o si ts e ro d e a n d o ve rl a p t h e f lu vi o g la ci a l l g m d e p o si ts , w h ile in t h e o u te r p a rt t h e se la tt e r e ro d e a n d o ve rl a p t h e f lu vi o g la ci a l p re -l g m d e p o si ts . t h e b o u n d a ri e s th a t d e fin e t h e se u n its a re s ig n ifi ca n t d is co n tin u iti e s, a n d w ith in e a ch s yn th e m e t h e se b o u n d a ri e s a re d ia ch ro n e s. t h e m a xi m u m e xt e n t re a ch e d b y th e g la ci e r d u ri n g t h e la st g la ci a tio n ( l g m b o u n d a ry ) is id e n tif ie d b y th e in n e r m a rg in o f th e la te ra l m o ra in e " b ". l a ck in g t h is m o ra in e r id g e , th e l g m b o u n d a ry ca n b e t ra ce d a p p ro xi m a te ly f ro m t h e g e o m e tr y o f th e c o n ta ct -g la ci a l a n d /o r p ro g la ci a l d e p o si ts . t h e d is tin ct io n b e tw e e n d iff e re n t fa ci e s w ith in a s yn th e m e is g ra p h ic a lly v is u a liz e d b y a n o ve rm a rk , w h ile c o lo u r a n d s yn th e m e in iti a ls r e m a in u n ch a n g e d . 78 proprio dalle esperienze di rilevamento condotte nell’ambito alpino italiano emerge che quanto è stato cartografato come depositi lgm nelle valli principali si colloca in un intervallo temporale abbastanza ben definito, compreso all’incirca tra 25 e 11 ka bp (date non calibrate), coincidendo quindi con lo stadio isotopico 2. tuttavia, allo stato attuale delle conoscenze, non si è sicuri della stretta contemporaneità degli eventi nei differenti bacini. inoltre, mentre nelle valli principali per i depositi glaciali riferibili allo lgm si osserva questa complessiva convergenza delle età, nelle catene periferiche prealpine (es. monti lessini), contraddistinte da piccoli ghiacciai locali con dinamiche proprie e non necessariamente sincrone con quelle dei grandi ghiacciai vallivi, tale evento può essere antecedente (es. stadio isotopico 4). allo stato attuale dei lavori le unità riferibili allo lgm hanno per la maggior parte il rango di sintema/alloformazione. il problema del rango si pone però nel caso di bacini molto articolati in cui le valli laterali, nel corso dell’ultimo evento glaciale, hanno ospitato masse glaciali che non sono mai state in relazione diretta con il ghiacciaio vallivo principale e la cui evoluzione non è necessariamente sincrona con questo (e fra di loro). una possibile soluzione potrebbe essere quella di elevare le unità riferibili allo lgm al rango di supersintema/allogruppo. un altro problema si pone per le aree d'alta montagna, dove i distinti ghiacciai vallivi erano uniti in un'unica zona d'accumulo: in questo contesto la suddivisione per bacini delle unità associate allo lgm non ha più significato. in tali contesti sarà necessario individuare soluzioni, sia di nomenclatura delle unità sia di resa grafica, idonee a rappresentare queste peculiari situazioni. 22.. ppoossttggllaacciiaallee per ppoossttggllaacciiaallee si vuole indicare in ambito alpino l’insieme di eventi, che si succedono a partire dal termine dell’ultima espansione glaciale locale. postglaciale non è sinonimo di olocene, ma rappresenta un evento corrispondente ad un arco temporale che va dalla parte terminale del pleistocene superiore all'olocene. pertanto, il postglaciale così definito non ha il significato di postglaciale presente in taluna letteratura, indicante un intervallo di tempo. 22..11.. ddeeppoossiittii eedd uunniittàà rriiffeerriibbiillii aall ppoossttggllaacciiaallee l’unità postglaciale (acronimo uuppgg) è una unità informale (cfr. 4a) che comprende tutti i depositi che si formano dopo il ritiro del ghiacciaio dello lgm da un data area. è un'unità ubiquitaria (cfr. 4e) ossia, a differenza delle unità associate allo lgm, non viene distinta sulla base dei bacini (idrografici e/o glaciali) di pertinenza degli agenti deposizionali che concorrono alla formazione dei suoi depositi, in quanto il suo limite superiore è l’attuale superficie topografica e può essere seguito con continuità da bacino a bacino. la sua superficie limite inferiore è evidentemente diacrona in quanto coincide con la superficie limite superiore dello lgm. proprio per tale motivo l’unità postglaciale non è equiparabile all’olocene. l’upg possiede il rango di sintema/alloformazione ed è marcatamente diacrona su tutta la sua estensione. in particolari contesti, l’upg potrebbe essere elevata al rango di supersintema/allogruppo. in ambito alpino l’upg può essere suddivisa in sottounità di uso strettamente locale per rappresentare singoli corpi rappresentativi di eventi deposizionali importanti a livello di un dato bacino, o di porzioni significative di questo (es. frane arealmente estese). nelle aree di alta montagna dove si hanno depositi glaciali legati alla piccola età glaciale (peg), evento sincrono per tutti i bacini, sono di uso generale le seguenti sottounità: la sottounità postglaciale inferiore. la sottounità postglaciale peg. la sottounità postglaciale superiore. si precisa che gli aggettivi “inferiore” e “superiore” hanno significato stratigrafico; depositi così denominati, presenti tanto in altri quanto nei medesimi ambiti, non necessariamente sono tra loro sincroni. tale classificazione si riferisce ad un ambito strettamente locale. la rappresentazione cartografica dell’upg dovrebbe avvenire mediante l’utilizzo di un unico colore esteso su tutti i bacini; le sue eventuali suddivisioni in sottounità andranno evidenziate mediante sigle. le differenze interne, date dalle variazioni laterali di facies, andranno rese mediante appositi sovrassegni. 22..22.. pprroobblleemmaattiicchhee iinn ccoorrssoo ddii ddiissccuussssiioonnee l’unità postglaciale viene trattata in modo specifico a seconda che si operi in ambito alpino o in ambito di pianura; appare evidente come in questi due diversi contesti l’upg abbia necessariamente età differenti. relativamente all’ambito della pianura, l’unità postglaciale comprende tutti i depositi di natura prevalentemente fluviale (ma anche lacustri/palustri) più recenti dei depositi fluviali/fluvioglaciali appartenenti ad unità associate allo lgm (vedi figura 1). all’interno di questi possono esser fatte distinzioni, con valenza locale (vedi il significato di sopra). per depositi legati ad eventi significativi, oppure sulla base di evidenze archeologiche o di datazioni, possono essere create delle sottounità assegnando a queste nomi locali. l’utilizzo dell’unità postglaciale pone problemi di logica in tutti quegli ambiti vallivi corrispondenti ad aree non glacializzate. in questi contesti, in assenza di depositi periglaciali correlabili con lo lgm, i depositi cartografabili nell’upg sono quelli che evidenziano rapporti con l’attuale sistema morfoclimatico o per i quali vi siano elementi di datazione numerica o relativa che consentano di differenziarli da quelli più antichi. per la cartografia di questi ultimi si rinvia al § 3.2. 33.. pprree llaasstt ggllaacciiaall mmaaxxiimmuumm pprree llaasstt ggllaacciiaall mmaaxxiimmuumm (pre lgm) indica l’insieme degli eventi che precedono l'ultimo massimo glaciale locale (lgm). i depositi ed unità riferibili al pre – lgm comprendono tutti i depositi legati ad eventi sedimentari precedenti lo lgm. come già visto per i depositi associati allo lgm, il loro studio e cartografia deve avvenire secondo una logica bacinale. inoltre, nello studio di tali depositi, occorre distinguere fra depositi glaciali (o comunque in chiara relazione con un evento glaciale) e depositi non glacigenici, in quanto cambia il a. bini et al. 79 modo in cui vengono inquadrati dal punto di vista stratigrafico e dunque cartografati. 33..11.. ddeeppoossiittii ggllaacciiggeenniiccii iinn aarreeee ddii aannffiitteeaattrroo nelle aree di anfiteatro l’identificazione e la cartografia dei depositi legati agli eventi sedimentari precedenti lo lgm sono attuabili senza problemi particolari. infatti, in questo contesto, caratterizzato da ampie superfici per la deposizione dei sedimenti e da limitata attività erosiva, i depositi sono solitamente ben conservati, permettendo il riconoscimento di diverse unità sulla base sia dei rapporti geometrici sia dei caratteri delle superfici limite superiori (morfologia, presenza di coltri eoliche, alterazione, ecc.). le differenze di caratteri consentono non solo la distinzione dei depositi riferibili allo lgm da quelli precedenti, ma anche il riconoscimento di vari sintemi /alloformazioni derivanti dagli episodi glaciali ad esso precedenti (vedi figura 2). possono però presentarsi casi in cui, pur in presenza di una successione di corpi sedimentari riconoscibili su base morfologica (es. morene e rispettive piane glaciali), non si riesca a distinguerli sulla base dei caratteri oggettivi della superficie limite superiore. in mancanza di tali dati non si riesce ad operare alcuna suddivisione in sintemi/alloformazioni, benché tali corpi siano dovuti ad eventi deposizionali diversi. tuttavia, in questi casi, è possibile istituire localmente delle unità informali (es. unità di…) per poi comprenderle tutte all’interno di un supersintema/allogruppo (vedi figura 2). 33..22.. ddeeppoossiittii ggllaacciiggeenniiccii ddeeggllii aassssii vvaalllliivvii in ambito vallivo e nelle valli tributarie dell’anfiteatro il discorso è più complesso in quanto subentrano due fattori assenti negli anfiteatri. “innanzitutto i sedimenti deposti durante i vari episodi glaciali occupano vaste aree negli apparati, dove i limiti delle massime espansioni raggiunte durante i vari episodi glaciali sono distanziati anche di parecchi chilometri, mentre sui versanti delle valli che afferiscono agli apparati, gli stessi sedimenti occupano aree limitate racchiuse in un piccolo intervallo di quote (spesso poche decine di metri). ossia a grandi variazioni frontali dei ghiacciai negli apparati corrispondono piccole variazioni in quota nelle valli. in secondo luogo sui versanti delle valli l'erosione è molto più intensa e quindi i depositi più antichi sono conservati solo come massi erratici isolati e/o piccoli lembi in luoghi più riparati” (bini et al., 2001). le esperienze di rilevamento hanno evidenziato come nell’ambito vallivo sia sempre riconoscibile l'unità associata allo lgm; inoltre nel tratto inferiore delle valli, a ridosso degli anfiteatri, sono spesso riconoscibili anche la/le unità più antiche relative alle glaciazioni precedenti lo lgm. ma al di fuori di questo limitato ambito, i depositi di ambiente glacigenico precedenti lo lgm si presentano frammentari e oggettivamente non più riconducibili alle unità riconosciute in anfiteatro. per semplificare e risolvere i problemi di cartografia, le esperienze maturate hanno portato a riunire i depositi precedenti lo lgm in un unico supersintema/allogruppo per ogni bacino (es. supersintema di xxx, bacino yyy). ovviamente tale supersintema/allogruppo cessa di esistere passando dall’ambito vallivo a quello dell’anfiteatro (vedi figura 2). dall’utilizzo di questo approccio, tenendo conto che le ubsu sono indipendenti dal concetto di tempo, consegue che l'intervallo temporale rappresentato dai depositi del supersintema/allogruppo vallivo include almeno gli intervalli temporali relativi ai depositi pre lgm compresi nei singoli sintemi/supersintemi dell'anfiteatro, ma non ne costituisce il raggruppamento a rango superiore. il supersintema/allogruppo dei depositi pre-lgm può venire cartografato in modo indistinto (cfr. 4c), oppure si possono riconoscere localmente corpi in successione stratigrafica o importanti per estensione: in questi casi vengono distinte ed istituite unità informali nell'ambito di quel dato supersintema/allogruppo (vedi figura 2). è opportuno sottolineare come tali unità non abbiano il valore di sintemi/alloformazioni (legati ad un singolo evento sedimentario valido a livello bacinale) ma di unità con significato strettamente locale, inglobanti sedimenti quasi sicuramente compresi in uno dei tanti sintemi/alloformazioni (oppure subsintemi/allomembri) presenti in anfiteatro, senza però potere definire univocamente a quali riferirle. 33..33.. ddeeppoossiittii nnoonn ggllaacciiggeenniiccii si tratta generalmente di depositi fluviali, di versante e di frana, talora cementati, ma anche depositi colluviali e, raramente, depositi lacustri. nel complesso si tratta di depositi slegati dalle vicende glaciali o, in ogni caso, non direttamente riconducibili ad esse. questi depositi possono essere cartografati all’interno di un gruppo (unità litostratigrafica), creato ad hoc in ogni bacino e che può essere suddiviso in unità formali (cfr. 4a) (es. formazioni) per corpi estesi e significativi, espressione di eventi sedimentari singoli, ma sempre di valore locale. per singoli affioramenti di piccola estensione è meglio usare il gruppo a livello indistinto. relativamente ai soli depositi cementati, solitamente poco estesi ed appartenenti a più episodi sedimentari, per rimarcarne il significato geologico, può essere conveniente cartografarli in un gruppo a sé stante, invece di istituire delle unità informali all’interno di un unico gruppo che racchiuda tanto i depositi cementati quanto quelli sciolti. l’approccio appena descritto può essere utilizzato anche nelle valli non glacializzate. ogni supersintema/allogruppo o gruppo dovrebbe essere rappresentato cartograficamente mediante l’utilizzo di uno specifico colore diverso da bacino a bacino; le sue eventuali suddivisioni in unità andranno evidenziate mediante sigle. le differenze interne, date dalle variazioni laterali di facies, andranno rese mediante appositi sovrassegni, laddove l’unità non sia indifferenziata (cfr. 4d). 44.. ssiiggnniiffiiccaattii ddeellllaa tteerrmmiinnoollooggiiaa uuttiilliizzzzaattaa a) unità formale/informale: termine relativo ai codici di stratigrafia. una unità formale risponde appieno alle definizioni dei codici; una unità informale non risponde pienamente a tali definizioni. b) unità formalizzata/non formalizzata: una unità formalizzata risponde appieno alle definizioni dei codici ed è stata validata dalla definizione di alcuni termini ... 80 a. bini et al. commissione italiana di stratigrafia. una unità non formalizzata è una unità formale non ancora formalizzata. c) indistinta/o: unità (di qualsiasi rango) non suddivisa in sottounità (es. gruppo non suddiviso in formazioni); rappresenta quindi una non divisione rispetto al tempo ed ai rapporti stratigrafici. d) indifferenziata/o: unità (di qualsiasi rango) non suddivisa al suo interno sulla base delle facies in essa presenti. e) ubiquitaria/o: unità (di qualsiasi rango) non distinta sulla base del bacino di appartenenza. 55.. ccoonncclluussiioonnii nel rilevamento dei depositi quaternari continentali in ambito alpino l’approccio alle tematiche esposte (come pure le di classificazione dei depositi in unità) dipendono dal contesto geologico in cui si lavora; le soluzioni cartografiche che possono essere adottate possono variare in funzione della scala della rappresentazione cartografica e delle possibilità grafiche che si hanno a disposizione. pertanto, il presente documento non vuole imporre soluzioni predefinite o vincolanti, ma fare chiarezza sul significato dei termini, in modo che 81 fig. 2 stralcio semplificato della carta geologia d5a4 “passirano” – scala 1:10.000 (regione lombardia, direzione generale territorio ed urbanistica, 2001). dati derivanti dai rilevamenti eseguiti per il progetto carg regione lombardia, in convenzione con il servizio geologico nazionale. la carta mostra il quadrante ne dell’anfiteatro morenico di franciacorta; tale area presenta sia le problematiche tipiche degli anfiteatri sia quelle degli assi vallivi, in quanto è bordata sul suo lato nne da rilievi montuosi con i quali, nel corso del quaternario, ha interagito il ghiacciaio vallivo camuno al suo sbocco in pianura. per questo motivo sono presenti sia le unità pre – lgm proprie dell’anfiteatro (in questa area sono: il supersintema di monterotondo rroott ed il sintema di monte pianeppii11)) sia le unità pre – lgm dell’asse vallivo (supersintema di monte alto aalloo). nell’area affiorano inoltre i depositi associati allo llggmm (sintema di iseo iiss) e quelli ad esso successivi (unità postglaciale ppgg). la distinzione fra le diverse facies dei depositi in un dato sintema è resa mediante un apposito sovrassegno, mentre colore e sigla del sistema rimangono invariati. osservazioni: 1. depositi glaciali dell’llggmm bordano le torbiere (lliimmiittee llggmm), mentre i suoi depositi fluvioglaciali fuoriescono dalla cerchia morenica lungo il paloeoalveo del t. longherone. tutti i depositi riferibili allo lgm sono stati cartografati come sintema di iseo. 2. nell’area di anfiteatro, all’esterno del sintema di iseo, affiorano le unità pre – lgm che sono state cartografate sia come sintemi (sintema di monte piane) sia come supersintemi (supersintema di monterotondo). quest’ultimo è stato localmente suddiviso in unità informali (dalla più interna alla più esterna, rispettivamente: unità di timoline rti, unità di borgonato rbo e unità di torbiato rto); allo stato attuale delle conoscenze non è possibile stabilire se queste unità corrispondano a pulsazioni di una stessa glaciazione o appartengano a distinti eventi glaciali. dove non è stato possibile operare tale suddivisione, si è cartografato il supersintema come indistinto (rroott). 3. nel settore ne dell’area, dove sono presenti i rilievi in substrato, in posizione esterna al sintema di monte piane si è cartografato il supersintema di monte alto, proprio dell’asse vallivo. tale scelta deriva dal fatto che non è stato possibile correlare i depositi presenti con le unità dell’anfiteatro s.s. anche in questo caso il supersintema è stato localmente suddiviso in unità di significato locale (unità di san pietro in lamosa – ala; unità di madonna del corno – ama; unità di pian delle viti – avi). dove non è stato possibile operare tale suddivisione si è cartografato il supersintema come indistinto (aalloo). 4. all’estremo n dell’area, subito ad e del supersintema di monte alto, è visibile un piccolo lembo del sintema di monte piane che prosegue verso n (per poche centinaia di metri), ormai in area valliva s.s. immediatamente dopo l’unità perde la sua evidenza sia morfologica che dei caratteri della superficie limite superiore. i depositi presenti sono stati fatti rientrare nel supersintema vallivo, data l’impossibilità di riferirli con sicurezza ad una delle unità dell’anfiteatro. simplified sketch from the geological map d5a4 “passirano” at the 1:10.000 scale (regione lombardia, direzione generale territorio ed urbanistica, 2001) derived from surveys made within the "progetto carg regione lombardia" in collaboration with the national geological survey. the map shows the ne part of the franciacorta glacial amphitheatre, where both amphitheatre and valley problems occur, because on the nne side the amphitheatre is bounded by mountain ridges that, during quaternary times, interacted with the val camonica glacier. because of this, within the area are present both pre – lgm amphitheatre units (monterotondo supersyntheme: rroott and monte piane syntheme: ppii11)) and pre – lgm valley units (monte alto supersyntheme: aalloo). furthermore lgm (iseo syntheme:iss) and post-glacial (unità postglaciale ppgg) are presents. the distinction between different facies within a certain syntheme is graphically visualized by an overmark, while colour and syntheme initials remain unchanged. some details: 1. the lgm glacial deposits surround the peat-mosses (lgm boundary), while their fluvioglacial counterparts spread out from the terminal moraine ridge along the longherone paleoriver-bed. all the deposits referred to the lgm were mapped as iseo syntheme. 2. in the amphitheatre, outer from the iseo syntheme, outcrop the pre – lgm units that were mapped both as syntheme (monte piane syntheme) and supersyntheme (monterotondo supersyntheme). the latter was locally subdivided into three informal units (respectively: unità di timoline rti, unità di borgonato rbo e and unità di torbiato rto). at the present state of knowledge it is not clear whether these units correspond to several pulses within the same glaciation or if they represent distinct glacial events. in the areas where it was impossible to distinguish these units the supersyntheme was mapped as indistinct (rroott). 3. in the ne part, where bedrock outcrops, in outer position with respect to monte piane syntheme, the monte alto supersyntheme is mapped within the axial part of the valley. this is due to the impossibility to correlate these deposits with the amphitheatre units. also in this case the supersyntheme was subdivided in local informal units (unità di san pietro in lamosa: ala; unità di madonna del corno: ama; unità di pian delle viti: avi). where it was impossible to distinguish these units the supersyntheme was mapped as indistinct (aalloo). 4. at the far north, just e from monte alto supersyntheme, we can notice a little outcrop of monte piane syntheme which continues northwards for few hundred meters within the valley. far north the unit looses both morphological evidence and the characteristics of the upper bounding discontinuity. because of the impossibility to unambiguously relate these deposits to a amphitheatre units, they were mapped within the valley supersyntheme. ➧ definizione di alcuni termini ... chi li utilizza o li affronta abbia un quadro di riferimento il più possibile chiaro ed univoco. inoltre alcune problematiche affrontate sono ancora in corso di verifica e confronto, e troveranno soluzione solo al termine dei lavori di rilevamento, quando si avrà a disposizione il quadro completo delle unità e si porterà a sintesi l’intero lavoro. e' necessario comunque precisare che il lavoro, in quanto frutto del confronto tra diversi autori con approcci metodologici differenti, rappresenta una piattaforma comune che non necessariamente riflette le idee espresse dai singoli autori in altri lavori pubblicati in precedenza. rriinnggrraazziiaammeennttii lavoro eseguito da componenti del “sottocomitato alpi gruppo di lavoro per il coordinamento del quaternario dei progetti carg dell’arco alpino”. si ringraziano tutte le persone che, a vario titolo, hanno offerto contribuiti utili ad approfondire gli aspetti delle problematiche sopraesposte, ed in particolare r. bersezio, g.b. castiglioni, v. maggi, g. orombelli, e c. ravazzi. bbiibblliiooggrraaffiiaa cciittaattaa:: bini a. (1997) problems and methodologies in the study of the quaternary deposits of the southern side of the alps. geologia insubrica, 22 ((22)). bini a., bosi c., carraro f. & orombelli g. (1989) rapporto novembre 1989. -commissione italiana di stratigrafia, gruppo di lavoro sul quaternario. bini a. e pellegrini a. (1998) geologia del quaternario. geologia insubrica, vol. 33 ((22)). bini a., felber m, pomicino n. & zuccoli l. (2001) geologia del mendrisiotto (canton ticino, svizzera): messiniano, pliocene e quaternario. berichte des bundesamt fur wasser und geologie, 11, 459 pp. crowley t.j. & north g.r., (1991) paleoclimatology. oxford university press, new york, 339 pp. international stratigraphic guide (1994). north american commission on stratigraphic nomencalture (1983) north american stratygraphic code. american association of petroleum geologist bullettin, 6677 (5): 841-875. penck a. & brückner e. (1909) die alpen im esizeitalter. leipzig, bd. 3. servizio geologico nazionale (2001) indicazioni per il rilevamento del quaternario continentale. documento interno sgn, 2001. s̆ibrava v., bowen d.q. & richmond g.m. (1986) quaternary glaciations in the northern hemisphere. report igcp n° 2244, quat. sc. rev., 5(1-4). 82 ms. ricevuto il 9 gennaio 2004 testo definitivo ricevuto il 9 febbraio 2004 ms. received: january 9, 2004 final text received: february 9, 2004 a. bini et al. impaginato santilli llaattee hhoolloocceennee eennvviirroonnmmeennttaall eevvoolluuttiioonn ooff tthhee uuppppeerr vvaallllee ddeell ggaalllloo ((cceennttrraall aallppss)):: aann iinntteerrddiisscciipplliinnaarryy ssttuuddyy mmaauurriizziioo ssaannttiillllii11,, mmaannuueellaa ppeellffiinnii11,, mmaarrccoo ccaacccciiaanniiggaa22,, rroobbeerrttoo ccoommoollllii33 && cceessaarree rraavvaazzzzii44 1dipartimento di scienze della terra, sezione di geologia e paleontologia, università di milano, via mangiagalli 34, 20133 milano (italia); e-mail: maurizio.santilli@unimi.it; e-mail: manuela.pelfini@unimi.it 2dipartimento di biologia, sezione di botanica sistematica, università di milano, via celoria 26, 20133 milano e-mail: marco.caccianiga@unimi.it 3dipartimento di scienze dell’ambiente e del territorio, università di milano-bicocca, piazza della scienza 1, 20126 milano; e-mail: roberto.comolli@unimib.it 4cnr, istituto per la dinamica dei processi ambientali, piazza cittadella 4, 24129 bergamo e-mail: cnrbg1@mediacom.it abstract through an interdisciplinary study based on the application of geomorphological, stratigraphic, dendrochronological, pedological and phytosociological methods, the late holocene environmental evolution of the valley bottom of the upper valle del gallo (upper valtellina / upper valle dello spöl, central italian alps), an area high in the mountains characterized by a strong environmental dynamism, has been reconstructed. the geomorphological survey and some stratigraphic sections prove that the studied area was occupied, probably from the late-glacial period, by a lacustrine basin. laminites, microturbidites, fluvial, deltaic and debris flow deposits formed by the progradation of the surrounding fans deposited in the lake and buried it before the middle holocene, originating a flat primitive valley bottom. this original surface was subsequently carved by the regressive erosion of the main river and its tributaries which isolated, especially since the middle ages, numerous surfaces from the more recent debris flow activity. some fans were partially dismantled while in some depressed sectors a succession of silty deposits formed by sheetfloods accumulated. the adaptation and the reaction of the arboreal vegetation to the debris flow activity allowed us to apply dendrogeomorphological techniques thanks to which some events were dated and the recent morphologic evolution of one of the fans reconstructed. the ecological succession takes place on two types of carbonatic substratum characterising the study area: sandy gravel deriving from debris flows, silt and fine sands deriving from sheetfloods. the soils and vegetation of the upper valle del gallo are generally scarcely developed. the vegetation is dominated by pinus montana forests at various degrees of evolution, following pioneer communities in which the pine plays a key role. the pedological study shows that pine forests develop on leptosols, poor and dry grounds rich in rock fragments of the fans, only locally susceptible of evolving into cambisols. these surfaces are frequently buried by debris flows that cover the grounds thus inducing regressive stages in the vegetational series. yet trees often survive these events since they are able to heal their scars, straighten themselves up and to develop adventitious roots from the buried base of the stems and branches. on the contrary fluvisols develop on sheetfloods silty deposits, where peculiar herbaceous communities predominate, adapted to a light periodic burial that does not kill the vegetation. last but not least must have been the influence of the anthropic deforestation, that has probably contributed in a considerable way to the present landscape setting. sommario evoluzione ambientale tardo-olocenica dell’alta valle del gallo (alpi centrali): uno studio interdisciplinare. mediante uno studio interdisciplinare basato sull’impiego di metodi geomorfologici, stratigrafici, dendrocronologici, pedologici e fitosociologici, è stata ricostruita l’evoluzione ambientale tardo-olocenica del fondovalle dell’alta valle del gallo (alta valtellina/alta valle dello spöl so), un’area d’alta montagna contraddistinta da un’elevata dinamicità ambientale. il rilevamento geomorfologico e alcune sezioni stratigrafiche documentano che l’area studiata era occupata, probabilmente a partire dal tardiglaciale, da un bacino lacustre. in esso si sono depositate laminiti, microtorbiditi, depositi deltizi, fluviali e di debris flows derivati dalla progradazione dei conoidi circostanti, che hanno interrato il lago prima della metà dell’olocene, dando origine ad un primitivo fondovalle pianeggiante. questa originaria superficie è stata successivamente intagliata dall’erosione regressiva del torrente principale e dei suoi affluenti, che ha isolato, soprattutto a partire dal medioevo, diverse superfici dall’attività più recente dei debris flows. alcuni conoidi sono stati parzialmente smantellati, mentre in alcuni settori depressi si è accumulata una successione di depositi limosi derivati da processi di sheetflood. gli adattamenti e la reazione della vegetazione arborea all’attività dei debris flows hanno consentito l’impiego di tecniche dendrogeomorfologiche mediante cui sono stati datati alcuni eventi ed è stata ricostruita l’evoluzione morfologica recente di uno dei conoidi. sui due tipi di substrato carbonatico che caratterizzano l’area di studio, ghiaie sabbiose derivanti da debris flows, limi e sabbie fini derivanti da sheetfloods, ha luogo la successione ecologica. i suoli e la vegetazione dell’alta valle del gallo sono, in generale, scarsamente evoluti. la vegetazione è dominata da pinete a pinus montana con gradi diversi di evoluzione, che seguono aggruppamenti pionieri in cui il pino gioca un ruolo chiave. lo studio pedologico indica che le pinete si sviluppano su suoli poveri, scheletrici e asciutti di conoide, i leptosols, solo localmente suscettibili di evolvere verso i cambisols. frequentemente queste superfici vengono sepolte da colate di detrito che ricoprono i suoli e inducono stadi regressivi nella serie vegetazionale. tuttavia, spesso gli alberi sopravvivono a questi eventi poiché sono in grado di rimarginare le cicatrici, raddrizzarsi e sviluppare radici avventizie dalla base sepolta dei fusti e dei rami. sui depositi limosi di sheetfloods, invece, si sviluppano fluvisols e prevalgono peculiari aggruppamenti erbacei adattati ad un leggero seppellimento periodico che non uccide la vegetazione. non meno importante deve essere stata, infine, l’influenza del disboscamento antropico, che ha probabilmente contribuito in modo notevole all’assetto del paesaggio attuale. keywords: alluvial fans, debris flows, holocene stratigraphy, dendrogeomorphology, mountain pine, alpine soils, vegetation. parole chiave: conoidi alluvionali, debris flows, stratigrafia olocenica, dendrogeomorfologia, pino montano, suoli alpini, vegetazione. il quaternario italian journal of quaternary sciences 1155(2), 2002, 187-208 188 m. santilli et alii 11.. iinnttrroodduuccttiioonn this report deals with the late holocene environmental evolution of the upper valle del gallo (upper valtellina / upper valle dello spöl, central italian alps). this area high in the mountains shows a peculiar landscape characterized by a strong dynamic of the slopes, by the aggradation of fans mostly originated by debris flows and by a hydrographic network which is progressively deepening. the upper valle del gallo is particularly suitable to study the frequency and the effects of some geomorphologic processes strictly associated with the atmospheric dynamics, especially with precipitation, on the environment. the reaction of vegetation to such a rapid geodynamics and to a specific bedrock geochemistry (carbonates) allowed us to analyse the ecological interactions between geomorphic and sedimentary processes, the soil evolution and the factors determining it (climate, human influence, etc.). moreover, this interdisciplinary research intends to promote the conservation and the enhancement of this area located between two wide protected areas, the stelvio national park and the swiss national park, showing at present a scant human presence. 22.. ssttuuddyy aarreeaa the valle del gallo is situated on the northeast extremity of the lombardy (northern italy), in the stelvio national park, (fig. 1). the studied area extends from passo di fraele (1952 m) to ponte di pra grata (1864 m) (fig. 1), and is entirely included in the carbonatic succession of the norian age related to the quattervals nappe, except for some klippen belonging to the scarl-umbrail system forming some mountain tops (pozzi & giorcelli, 1960; bonsignore et al., 1969; berra, 1994). as showed by the analysis of the data (santilli, 2000) from the meteorological station in cancano (aem milano, 1948 m a.s.l., see fig. 1), the climate of the upper valle del gallo corresponds to the alpine continental one (fig. 2). the average annual precipitation are scarce (822 mm), but, due to the altitude, the potential evapotranspiration is rather limited (428 mm). the soil water balance shows a small deficit in july. the carbonatic bedrock, the diffuse cover of coarse detrital sediments and the soils features reduce the available water capacity; consequently some aridity problems can occur during dry years. due to the high altitude of the surrounding mountains (up to 3180 m), wide portions of the slopes are beyond the tree limit and are without vegetative cover. hence the climate is favourable for a strong weathering which can produce large quantities of debris that, accumulating on the slopes, are susceptible of moving due to the frequent heavy summer storms. as regards vegetation, the studied area is included in the upper subalpine belt and is dominated by monospecific pinus montana forests. pinus montana in the fig. 1 location, hydrography and orography of the studied area. the valle del gallo covers the area northward the passo di fraele and belongs to the hydrographic basin of the black sea (through the danube). the box shows the area represented in fig. 5. ubicazione, idrografia e orografia dell’area studiata. la valle del gallo si estende a nord del passo di fraele e appartiene al bacino idrografico del mar nero (attraverso il danubio). il riquadro mostra l’area rappresentata in fig. 5. broadest sense of the word (pinus mugo aggregate, according to minghetti, 1997; pinus of the mugo group according to pignatti, 1982; see also: hess et al., 1967; gaussen et al., 1993) includes two main species: pinus mugo turra 1764, having a dwarf habitus, which prefers carbonate substrata and grows in the eastern alps and in the carpathian, and pinus uncinata dc. in lam & dc. 1805, having an arborescent habitus, which prefers siliceous substrata and grows in the western alps and in the pyrenees. moreover they are different for several morphological features such as the cone shape or the needle anatomy. nevertheless, they frequently originate intermediate or hybrid forms hard to be taxonomically located. mountain pines of the valle del gallo have a prevalent arborescent habitus (see fig. 3), but even if this feature seems to be proper to pinus uncinata dc., its geographical and ecological location is similar to that of pinus mugo turra, thus in the present study the generic definition of “mountain pine” is preferred. the valley was subject to an intense anthropic 189late holocene environmental evolution ... exploitation for the presence of rich iron deposits that surface on its slopes. the mining activity, documented from 1272 to 1875, helped the development of a prosperous industry, that brought about the building of roads, structures and furnaces for the mineral fusion (agostoni,1923; leoni, 1953a-b; zazzi, 1982). the furnaces were fed with coal produced in the several charcoal pits which are still disseminated all over the valley; the wood was obtained by felling the mountain pines and removing their stumps. the intense deforestation has probably had a great influence on the recent evolution of the soil and vegetation. the bibliography available on the natural history of the valle del gallo is rather limited. general geomorphological information was provided by giorcelli (in pozzi & giorcelli, 1960) and by saibene (1973). these authors pointed out a series of erosive cycles of the neogenefig. 2 ombrothermic diagram by walter & lieth and soil water balance according to thornthwaite on the basis of the data of the meteorological station in cancano (aem milano, see fig. 1). the temperature and precipitation course shows the absence of an aridity period (p>2t) and a continental-like pluviometric system; the soil water balance shows a little deficit in july. the awc calculated (35 mm) refers to a skeletal soil representative of the fan. diagramma ombrotermico di walter & lieth e del bilancio idrico del suolo secondo thornthwaite in base ai dati della stazione meteorologica di cancano (aem milano, cfr. fig. 1): gli andamenti delle temperature e delle precipitazioni indicano l’assenza di un periodo di aridità (p>2t) ed un regime pluviometrico di tipo continentale; il bilancio idrico del suolo mostra un piccolo deficit nel mese di luglio. l’awc calcolata (35 mm) si riferisce ad un suolo scheletrico rappresentativo dei conoidi. fig. 3 remarkable scar on the stem of a mountain pine hit by a debris flow in 1959. the development of compression wood contributes to the trunk straightening, following its inclination. the box represents a stem section showing compression wood (darker in the lower part) and a corrasion scar (in the upper part); both of them date back to 1986. (photos by santilli). grossa cicatrice sul fusto di un pino montano investito da una colata di detrito risalente al 1959. lo sviluppo di legno di compressione coadiuva il raddrizzamento del tronco successivo alla sua inclinazione. il riquadro raffigura una sezione di fusto mostrante legno di compressione (più scuro in basso) e una cicatrice d’abrasione (in alto); entrambi risalgono al 1986 (foto santilli). 190 quaternary mainly caused by glaciations. glacial erosion on the main valleys promoted a regressive erosion and fluvial captures which modified the ancient hydrography. useful information on vegetation is available in furrer (1914), furrer & longa (1915), braun blanquet et al. (1954), giacomini & pignatti (1955), pirola & di benedetto (1959), giacomini (1960), pirola (1973), pedrotti et al. (1974), minghetti (1996). 33.. mmaatteerriiaallss aanndd mmeetthhooddss the environmental setting of the upper valle del gallo was deduced from the integration of a detailed geomorphological survey with photointerpretation (photograms no. 11-12-13, stripe 55, flight tem 1 regione lombardia 1981, and no. 2571-2572, flight alifoto 1975), and with stratigraphic, dendrochronological, pedological and vegetational studies. a general research was carried out on the whole valley sector and a more detailed study on the valle della casina fan, one of the lateral valleys. moreover some historic information was provided by some photographs dating back to the end of the 19th century, and by a map of the land register of 1844 “mappa del comune censuario di valle di dentro”. seventeen stratigraphic sections were described. some buried layers rich in organic matter and a charred wood were dated through radiocarbon. the definition of stratigraphic units is the one used by the international stratigraphic code (salvador, 1994). some debris flows of the valle della casina fan were dated using dendrogeomorphological techniques (e.g. see: alestalo, 1971; shroder, 1980; heikkinen, 1994; strunk, 1995) applied to mountain pines. more than two hundred increment cores were extracted from damaged pinus montana, along the valle della casina fan channels and some cross-sections of stems and branches were made. the trees showed corrasion scars and/or compression wood on slanting stems, both caused by the impact of debris carried by water on the stems (fig. 3). the compression wood is produced by conifers in order to bring the stem back to its vertical position whenever its orientation is altered. the scars and the year of appearance of the compression wood were dated. owing to the fact that the trees were usually heavily damaged, the ring recognition and counting on many samples were often difficult. finally only 53 trees were useful for dating purposes. some historical data together with daily precipitation recorded at the meteorological station in cancano (after 1961) confirmed some episodes which had been dated, even if it is not so easy to correlate the occurrence of the debris flows with precipitation (e.g. see: govi et al., 1985; polloni et al., 1991; govi et al., 1994; flageollet et al., 1999; van asch et al. 1999). thirty-two pedological profiles have been dug. for each horizon the color, the roots, the skeleton, the structure, the texture, the boundaries and the effervescence to hcl have been considered (according to sanesi, 1977). the analysis carried out in laboratory, on the fine earth, sifted at 2 mm, determined the organic carbon (oxidation with bichromate potassium), the ph (soil/water ratio 1:2.5), the total carbonates (gas-volumetric method) and the apparent texture (by smoothing with an esenwein’s pipette) (according to the osservatorio nazionale pedologico, 1994). soils have been classified according to the world reference base for soil resources taxonomic system (isss-isricfao, 1998). vegetation has been studied by using the phytosociological method of the zurich-montpellier school (braun-blanquet & jenny, 1926; braun-blanquet, 1964). thirty-eight relevés have been processed by using the braun-blanquet cover-abundance scale modified by pignatti (1952), in areas considered homogeneous from a geomorphological point of view. upgma has been used as clustering method to carry out the cluster analysis. a first analysis has been performed with the chord distance index using the cover values of the species transformed into numerical values (van der maarel, 1979). the following one has been carried out by using m. santilli et alii fig. 4 panoramic photo of the upper valle del gallo (see fig. 5): val paolaccia fan (1), valle della casina fan (2), val mora fan (3), “valle del pizzo aguzzo” fan (4; actually, the valley does not have any place-name), inactive fan (5a-5c) and active fan (5b) of val bruna, moraine (6) (photo by santilli). panoramica dell’alta valle del gallo (cfr. fig. 5): conoide della val paolaccia (1), conoide della valle della casina (2), conoide della val mora (3), conoide della “valle del pizzo aguzzo” (4; in realtà la valle è priva di toponimo), conoide inattivo (5a-5c) e conoide attivo (5b) della val bruna, morena (6) (foto santilli). 191 the jaccard coefficient and the data relevant to the species presence/absence. sporadic species have been excluded from the clustering processing. the floristic nomenclature is the one used by pignatti (1982). 44.. rreessuullttss 44..11.. ggeeoommoorrpphhoollooggiicc ssuurrvveeyy debris flow fans with a complex structure most of which are coalescent and come from both the valley sides occupy the upper valle del gallo. (fig. 4-5). creeks, often active only during heavy rains, sink on the eastern slope of the fans near their apexes. on the contrary, on the western slope they partially flow on their respective fan surface before sinking. this mirrors the northward/northward-eastward dipping of the strata (saibene, 1973). at the valley head the val paolaccia fan completely occupies the valley bottom (1 in fig. 4-5) originating the passo di fraele. the valle della casina (2) and the val mora fans (3) extend on the eastern valley side late holocene environmental evolution ... fig. 5 map of the fans and of the quaternary deposits of the upper valle del gallo (see fig. 4) (from the regional technical map 1:10.000 sections n° d1b3 “lago di livigno sud” and n° d1c3 “s. giacomo di fraele”, realisation 198083; coordinates are in the gaussboaga system). carta dei conoidi e dei depositi quaternari dell’alta valle del gallo (cfr. fig. 4) (dalla carta tecnica r e g i o n a l e 1:10.000, sezioni n° d1b3 “lago di livigno sud” e n° d1c3 “s. giacomo di fraele”, r e a l i z z a z i o n e 1980-83; le coordinate sono nel sistema gaussboaga). 192 while the “valle del pizzo aguzzo” (4) and the val bruna ones occupy the western slope (5). the latter is composed of a central active portion (5b), a southern inactive part (5a) and a northern one (5c) located westwards of a hillock (6). according to giorcelli (in pozzi & giorcelli, 1960) this hillock is a moraine deposited during the gschnitz stadium (early late-glacial). the val mora fan and the southern part of the val bruna one (5a) are now inactive surfaces bordered by scarps, up to 50-m high, facing the val bruna, val mora and valle del gallo the respective rivers of which flow at lower altitudes. these surfaces are considered (according to martina, 1954) as the remains of an ancient flat valley bottom successively dissected by acqua del gallo, the river of the main valley, and its tributaries; other edges of the same valley bottom are represented by some small parts of the valle della casina and “valle del pizzo aguzzo” fans. near the val paolaccia fan, the river acqua del gallo carves silty deposits (see par. 4.2.3.). the border of terraces formed by the crack has a winding shape which is more evident down the valley and represents an area where erosion gives birth to small incisions separated by crests (see fig. 8). the valle della casina fan (figs. 4-5-6) extends nearly for 1 km between an altitude of 2020 and 1885 m a.s.l. there is a main channel (a in fig. 6) near the northern margin; it is normally dry and marked by terraces separating other channels and interchannel zones with pinus montana forests. a part of the channel is edged by a high debris terrace (d). downhill the val mora road (1935 m) the channel still carves the fan until it forms a ten-meter deep scarp before flowing into acqua del gallo. two secondary channels (b) and (c) originate from the main channel (a). channels (a) and (b) border a zone with a discontinuous vegetation and dwarf and damaged trees (e). nearby there is another zone covered with a taller and thicker forest (f). channel (g) originates from the secondary channel (c). finally, at the fan-toe a few meter above the creek acqua del gallo a terrace (h) exists. 44..22.. qquuaatteerrnnaarryy ssttrraattiiggrraapphhyy the quaternary deposits cropping out on the valley bottom of the upper valle del gallo have been assigned to three lithostratigraphic units, the names of which derive from specific localities: the acqua del gallo unit, the valle della casina unit and the val paolaccia unit (fig. 5). 44..22..11.. aaccqquuaa ddeell ggaalllloo uunniitt description and interpretation. the acqua del gallo unit is a carbonatic clay sedimentary succession with a coarsening-upward sequence (fig. 7). the lower part is formed by massive grey clays; the middle part by horizontally laminated clays alternating between levels of silty clays and fine sands in fining-upwards laminas. deposits are interpreted as decanted laminites and microturbidites deposited in a lacustrine environment. the uppermost part of the succession alternates between graded and well-sorted sands, silt and silty clays. the succession is clast free. plant remains and macrofossils were not observed. thickness. the maximum visible thickness is 8 m (section 3; figs. 5-6-7); the estimated thickness is at least 35 m, between 1885 and 1920. name. its name comes from the creek that carved it and exposed the succession. lateral extent and relations with the other m. santilli et alii fig. 6 morphological sketch map of the valle della casina fan. the box shows the area represented in fig. 11. schema morfologico del conoide della valle della casina. il riquadro mostra l’area rappresentata in fig. 11. stratigraphic units. boreholes carried out by aem milano at the passo di fraele (giorcelli in pozzi & giorcelli, 1960) and the exposed sections along the river bed of acqua del gallo allow us to identify these lacustrine deposits for more than 2 km from the inactive fan of val bruna (5a in figs. 4-5) to passo di fraele. the uppermost part of the acqua del gallo unit is interdigitated with alluvial deposits included in the valle della casina unit. type section. section 3 (fig. 7; appendix i); coordinates: 46° 34' 00'' n, 10° 14' 40'' e. age. no direct dating is available for this unit. considering its stratigraphic position, it is older than 4710 ± 90 14c yr b.p. (tab. 1; see par. 4.2.2.). previous studies. giorcelli (in pozzi & giorcelli, 1960) mentions a paleolake originated by the erosion processes of the last glacial cycle that caused the formation of a watershed in the upper valle del gallo, and by the obstruction of the val paolaccia fan at the passo di fraele. 44..22..22.. vvaallllee ddeellllaa ccaassiinnaa uunniitt description and interpretation. this unit (fig. 5) is made up of several interdigitated bodies of gravelly deposits expanding on the valley bottom at the base of tributary valleys. each element is composed of lenticular successions, scantily stratified, of clast-supported gravel beds with sandy matrix, occasionally separated by wellsorted sandy-silty levels. both fine fraction and clasts are carbonatic but locally are siliceous erratic, metamorphic clasts and iron ores. clasts have a subangular or subrounded shape, are chaotic or have a weak stratification, with sands and a high primary porosity. buried soils are common; brownish silty horizons rich in coal are sporadically embedded. the entire succession is markedly inclined towards the valley bottom and distinctly finingdownward. it can be considered as a series of wedge-shaped and coalescent debris flow fans. the uppermost part of section 3 (acqua del gallo unit) shows the progradation of a fan covering gravelly and sandy alluvial deposits. the latter differ from the debris flow deposits because they are organized in channel bars, are better sorted, graded and partially stratified. they are included in the valle della casina unit. name. the present study analyses in detail the fan of valle della casina. boundaries and relations with the other strati193late holocene environmental evolution ... table 1 radiocarbon dating. date 14c. fig. 7 section 3 of the acqua del gallo unit (see appendix i) sezione 3 dell’unità dell’acqua del gallo (cfr. appendice i). graphic units. the exposed upper surfaces are characterized by an active aggradation or by the development of leptosols (locally cambisols) (see par. 4.4.). the basal part of the unit is interdigitated with lacustrine deposits of the acqua del gallo unit. some fans are interrupted by river downcuttings, between which the val bruna subunit (see further on) is embanked. a depressed sector in the southern part is covered by the val paolaccia unit. the contact surface is marked by a buried leptosol, locally eroded (see fig. 10 and par. 4.2.3.). age. a thin layer rich in coal at the “valle del pizzo aguzzo” fan-toe (see fig. 6) was dated 4710 ± 90 14c yr b.p. (tab. 1). a buried charred wood embedded in silty, reddish horizons rich in coal and partly pedogenized between gravelly layers in the upper part of the valle della casina fan (section 5 in fig. 6) was dated 1720 ± 50 14c yr b.p. (tab. 1). some recent surfaces (since the end of the 19th century) were dated through dendrogeomorphology. previous studies. these fans were mentioned by martina (1954), borgonovo (1955) and giorcelli (in pozzi & giorcelli, 1960). selected sections. no. 5 (coordinates: 46° 34' 10'' n, 10° 15' 00'' e; appendix i), 6 (46° 34' 00'' n, 10° 15' 10'' e) and 19 (46° 34' 10'' n, 10° 14' 50'' e) (fig. 6). subunits. the deposits embanked in the valle della casina unit and separated from the latter by an erosional surface were assigned to the val bruna subunit. the latter includes the active part of the val bruna fan (from which the name derives 5b in fig. 5) and the northern sector of the “valle del pizzo aguzzo” fan (fig. 5). the terrace (h) (fig. 6; see fig. 13) of the valle della casina fan is considered as a part of the “valle del pizzo aguzzo” fan separated by the erosion activity of the creek acqua del gallo. sections 40 and 46 (fig. 6; see fig. 13), coordinates 46° 34' 10'' n, 10° 14' 40'' e, are representative of this subunit. the buried soil included in section 46 was dated 3910 ± 60 14c yr b.p. (tab. 1). 44..22..33.. vvaall ppaaoollaacccciiaa uunniitt d e s c r i p t i o n a n d i n t e r p r e t a t i o n . the val paolaccia unit (fig. 8) is formed by a succession of centimetric layers made up of an undulating stratification of massive and well-sorted carbonatic silts and fine sands up to more than 4-m thick and totally clast-free. coal fragments are locally common, dispersed, concentrated in pockets or related to pedoturbations. pedogenized horizons and pedoturbations can only be found in the uppermost part (see section 2 in fig. 9 and appendix i). the structure of this succession suggests that it was formed in a terrestrial environment. the fine grain size, the good selection and the massive structure indicate that each layer resulted from the accumulation of single sheetfloods. these processes occur when dilute mixtures of water and sediments flow as traction currents spreading on the fan surface (bull, 1972; nichols, 1999). they cause a thin burial which does not kill the vegetation (see par. 4.5.3.), which promptly reacts by developing new roots and emerging stems. this also explains the common pedoturbation associated with the pedogenized horizons observed in the upper part of the succession. name. these sheetflood deposits come from the val paolaccia (figs. 58). 194 m. santilli et alii fig. 8 val paolaccia unit: location, extent, erosion morphologies (in the box) and location of the stratigraphic sections (numbers). unità della val paolaccia: localizzazione, estensione, morfologie d’erosione (nel riquadro) e ubicazione delle sezioni stratigrafiche (numeri). 195late holocene environmental evolution ... lateral extent, thickness and relations with the other stratigraphic units. the unit is interdigitated with the gravel deposits forming the val paolaccia fan and covers with an onlap contact the depressed sectors around it. these fine deposits can also be found on the fan surface where they locally bury the soil and vegetation with a layer up to 10-15-cm thick. some thicker successions have been observed in wide natural downcuttings in the north-west sector of the unit. sections 39 and 49 show the contact with the valle della casina unit marked by a buried leptosol (locally eroded) (figs. 8-9-10). selected sections. no. 39, 49, 2 (coordinates: 46° 33' 50'' n, 10° 14' 50'' e; figs. 8-9-10; appendix i). age. the tops of horizon a of the soil lying on the upper surface of the valle della casina unit and buried under the val paolaccia unit provided two dates (figs. 6-9-10, tab. 1). we think that the difference between these dates, respectively 1270 ± 70 14c yr b.p. (section 39) and 2570 ± 70 14c yr b.p. (section 49) depends on the different time of burial, which is related to their altitudinal position: the soil at a lower altitude was buried earlier. therefore, the difference observed in the ages provides a rough estimation of the average sedimentation rate (0.6 mm/yr). 44..22..44.. ddeeppoossiittss ooff uunnsseettttlleedd ssttrraattiiggrraapphhiicc ppoossiittiioonn some blocks of monogenic clast-supported conglomerates, locally passing to medium sandstone, were found along the river bed of acqua del gallo. clasts are carbonatic and the red or grey matrix is scarce. the provenance of this material is unknown. surveys carried out by the aem milano at the passo di fraele detected conglomerate layers embedded in the gravel. moreover a conglomerate layer a few centimetre thick is embedded in the sequence of clay, gravel and sands along the escarpment of the val bruna fan. fig. 9 stratigraphic sections of the val paolaccia unit coming into contact with the valle della casina unit (see appendix i). sezioni stratigrafiche dell’unità della val paolaccia al contatto con l’unità della valle della casina (cfr. appendice i). 44..33.. ddeennddrroocchhrroonnoollooggyy ooff ddeebbrriiss fflloowwss the dendrogeomorphological study concerns the most recent history of the valle della casina fan. the integration of the historical, meteorological and dendrochronological data allowed us to reconstruct the following chronological sequence of debris flows in the valle della casina (fig. 11) (santilli & pelfini, 2002). the oldest dated debris flow occurred at the end of the 19th century: five trees in area (f) showed compression wood events dating back to 1888. two close dates obtained by analysing eleven trees located in channel (b), area (f) and terrace (d) are 1927-1929. this could be considered as a single episode. between 1936 and 1941 four damaged trees in areas (e) and (f) were sampled. two scars dating back respectively to 1936 and 1941, point out that probably different debris flows were responsible for them. a tree located in the secondary channel (b) was damaged in 1953. this debris flow can be connected to a flood, which occurred after heavy rain between 12th and 13th august (borgonovo, 1955). clear scars on three trees located in the secondary channels (b) and (c) witness an event that took place in 1959 (see fig. 3). the damage on a tree located in area (f) jutting out in the main channel (a) witness a debris flow in 1964 (see sample (c) in fig. 5). heavy rain occurred on june 2nd (34.2 mm) and october 8th (42.8 mm). a flood which occurred in 1978 left traces everywhere; twenty-one damaged trees, in the main channel (a), in the secondary channels (b) and (g), and on the terrace (d), were sampled. this event is witnessed by the aerial photographs: the secondary channel (g) does not appear in 1975 whereas it is present in 1981 photos. heavy rain was recorded on may 21st-22nd (57.3 mm), june 24th (58.2 mm) and july 4th-6th (84.7 mm). nine damaged trees located in the main channel (a), in the margin of area (f) and in the upper part of the terrace (d) witness an event occurred in 1986. intense precipitation took place on august 19th (43,8 mm). finally a debris flow in 1992 is documented by five trees located in the main channel (a) and on terrace (d). this event coincides with a general flood of the whole upper valtellina, that caused a lot of damage especially near bormio, where 74 mm of rain fell in 2.5 hours on july 22nd (mortara et al. 1994); the station in cancano recorded 40.8 mm on july 23rd, but heavy rain also fell on june 19th-20th (67.2 mm) and on october 6th (39.4 mm). 44..44.. ssooiill ttyyppeess four soil reference groups have been identified: leptosols, cambisols, fluvisols and regosols. leptosols. they are shallow scarcely developed soils, with an (a)c or ac profile. they develop on sandy-matrix carbonate gravel (e.g. valle della casina unit) and belong to the most represented group including four different types of soil. 1. calcari-hyperskeletic leptosols. they are made up of coarse pebbles superficial layers (ac or ca) under which fine material accumulates. the layer, which may contain a significant amount of organic matter, is very modest and discontinuous. it lacks in structure and its skeleton is mainly made up of gravel with a sandy texture matrix. its colors are usually light (hue 2,5y), the effervescence is quite strong and the ph is definitely basic. 2. calcaric leptosols. horizon o (oi + oe) is 3-4cm thick; horizon a is 10-cm thick and can assume dark colors. its structure is scarcely developed, its texture is silt loam or sandy loam, its organic carbon content is of 29-35 g/kg. the amount of carbonates is high (676-757 g/kg), therefore its reaction is basic, too (ph 7.6-8.0). 3. calcari-humic leptosols. horizon o (oi + oe) is 2-4-cm thick; horizon a is usually about 10-cm thick, has dark colors (often 10yr 2/2), a weakly or moderately marked fine or medium granular structure, is rich in rock fragments, has a sandy loam texture, a very light or null effervescence, a ph of 7.4-7.9, a 51-97-g/kg organic carbon content and a variable total carbonate content (61-595 g/kg). 196 m. santilli et alii fig. 10 stratigraphic scheme of the northwestern sector of the val paolaccia unit. schema stratigrafico del settore nordoccidentale dell’unità della val paolaccia. 4. humi-rendzic leptosols (calcaric). horizon o (oi + oe; which is sometimes totally absent, and sometimes includes also oa) can be up to 4-cm thick; horizon a, which can sometimes be divided into two subhorizons having the characters of the mollic epipedon, is usually 10-25-cm thick, has a dark color (10yr 2/1-2/2), a weakly or moderately marked fine or medium granular structure, is rich in rock fragments, has a mostly sandy loam texture, a ph varying from 7.0 to 7.9 (seldom lower than 7.0), a very variable total carbonate content (0-569 g/kg) and a 12-130-g/kg organic carbon content. a subordinate fraction of parent material is locally siliceous (see par. 4.2.2), what reduces the carbonate content in lower horizons. cambisols. they are moderately developed soils, with an abc profile and a cambic b horizon (bw). cambisols develop on carbonate gravel, with a local subordinate siliceous fraction. these soils are little represented, and only one type of them exists. skeleti-calcaric cambisols. horizon o (oi + oe) is 1-2-cm thick; horizon a is not more than 10-cm thick, does not have very dark colors (10yr 3/2-4/3), contains few or normal rock fragments, has a moderately marked fine or medium granular structure, a sandy loam or silty loam texture, a weak or null effervescence, a variable total carbonate content (10-559 g/kg), an organic carbon content between 33 and 75 g/kg and a ph of 6.7-7.8. horizon bw is about 15cm thick, is brown (10yr 3/3-3/4), has a moderately marked medium granular structure, a loamy, sandy loam or silty loam texture, a variable effervescence, a total carbonate content between 108 and 601 g/kg, a ph of 7.8-8.0 and a 1836 g/kg organic carbon content. fluvisols. these soils have an (a)c or ac profile, and sheetflood sediments are periodically brought to them determining the stratification of the parent material and an irregular content of organic matter along the profile. fluvisols are only located on silty deposits without rock fragments in the val paolaccia unit. calcaric fluvisols. horizon o (oi and/or oe) has little importance (0-2 cm) and can also be absent; topsoils (a horizon) have very variable characteristics: their thickness is between 2 and 25 cm, they have light (2,5y 5/2) to dark (10yr 2/2) colors, a moderate to strong effervescence, a ph of 7.5-8.3, a very scarce decarbonatation (549-946 g/kg caco3, whereas the caco3 content in the parent material is only slightly higher) and a 4-80 g/kg organic carbon content. the pedogenesis is always weak, and the dynamic characteristics of the deposits give rise to buried horizons, which can be distinguished by a weak structure and by a little accumulation of organic matter. regosols. soils with a limited development not belonging to other soil groups. anthropic regosols. these soils develop on little level areas for the charcoal production which are very widespread in this zone. the topsoil is made up of a black layer of pure charcoal, about 20cm thick, that can be divided into two levels: the upper one differs from the 197late holocene environmental evolution ... fig. 11 dating of debris flows: event-response yearly maps pointing out the position of the sampled trees used for dating purposes; the black circles indicate the specimens in which event years (corrasion scars or first developing compression wood) relevant to the same episode were identified. the box is showed in fig. 6. datazione dei debris flows: mappe annuali evento-risposta mostranti la posizione degli alberi campionati utilizzati per le datazioni; i cerchi neri indicano gli individui in cui sono stati identificati anni caratteristici relativi ad uno stesso episodio (cicatrici d’abrasione o inizio dello sviluppo di legno di compressione). l’area è mostrata in fig. 6. 198 m. santilli et alii lower one in a more acid reaction (respectively ph 5.7 and ph 7.1) and in a weak structure granted by the roots. many leptosols and cambisols show some traces of surface erosion causing a partial lack in vegetation and emerging roots on a remarkably wide surface. 44..55.. ppllaanntt ccoommmmuunniittiieess three main groups of relevés have been identified through the chord distance analysis: pioneer lithophilous communities, mountain pine-dominated woods and scrubs, and grasslands. a further distinction has been made through the presence/absence analysis. 44..55..11.. ppiioonneeeerr lliitthhoopphhiilloouuss ccoommmmuunniittiieess (tab. 2) a sparse herbaceous layer, locally associated with a thin layer of young/small pines characterizes these communities. the cover values never exceed 20-30% and are sometimes lower than 5%, according to the age and the stability of the surface. the average number of species per relevé is 18. the moss layer has a negligible cover value while lichens lack. these communities are characterized by the constant presence of hieracium staticifolium, as well as of pinus montana and of many lithophilous and basiphilous species such as trisetum distichophyllum, saxifraga caesia and athamanta cretensis. other species are sporadically present and are sometimes linked to peculiar local parameters such as a higher humidity (e.g. saxifraga aizoides). these communities belong to the association athamanto-trisetetum distichophylli (jenny-lips 1930) lippert 1966 (class thlaspietea rotundifolii br.-bl. 1926 et al. 1948, order thlaspietalia rotundifolii br.-bl. in br.bl. & jenny 1926 em seib 1977, alliance petasition paradoxi zollitsch 1966). the importance of pinus montana in this pioneer vegetation, which is instead usually found only in the most advanced stages of the association (pirola & di benedetto, 1959), must be stressed. 44..55..22.. mmoouunnttaaiinn ppiinnee wwooooddss aanndd ssccrruubbss (tab. 3) pinus montana woods and scrubs dominate the vegetation of the upper valle del gallo. the vegetative cover is nearly complete, even if in pioneer or degraded stages it can reach low values (<50%). the arboreal layer, where present, has a mean cover value of 60% and is 4 to 8-m high, while the shrubby layer (locally including juniperus nana) has a mean cover value of 35% and is 0.3 to 3-m high. the herbaceous layer is well developed and reaches a cover value of about 70%. both mosses and lichens reach a cover value of 15-20%. these communities share in general xerophitic and heliophilous characteristics and seem quite homogeneous. nevertheless, some different aspects can be observed. the syntaxonomic treatment of pinewoods is difficult because of the uncertain taxonomy of the pine itself. according to minghetti (1996), all the sampled communities should be included in the class ericopinetea horvat 1959, order erico-pinetalia horvat 1959, alliance erico-pinion mugo leibungut 1948. ca r e x h u m i l i s a n d se s l e r i a v a r i a-d o m i n a t e d pinewoods. these groupings are joined together by some exclusive or preferred species like polygala chamaebuxus, calamagrostis varia and daphne striata, and by high cover values of erica carnea, carex humilis and sesleria varia. two main situations can be identified. 1. pinewoods on stabilized substrata. they are characterized by a wider cover of arboreal layer, by some species indicating that the soil has started to acidify (moneses uniflora and hieracium tenuiflorum) and by an accumulation of organic matter. according to the tree layer and erica carnea cover, the presence and abundance of vaccinium vitis-idaea and the average number of species, four different degrees of evolution can be identified: low degree of evolution. young pinewoods or scrubs, having a scanty arboreal and erica carnea cover. the average number of species is 32. intermediate degree of evolution. a thicker tree layer, a wider heather cover and a greater average number of species (35) characterize it. a group of differential table 2 synoptic table of the pioneer lithophilous communities. this table (see also tab. 3-4) shows the percentage frequencies of the most widespread species in the relevés, except in those represented by one single relevé, where the cover values are directly reported. tabella sinottica delle comunità pioniere litofile. questo tipo di tabella (cfr. anche tab. 3-4) mostra le frequenze percentuali delle specie più diffuse nei rilievi, eccetto nelle tipologie con un solo rilievo, dove sono direttamente riportati i valori di copertura. species, some of which are linked to grasslands, is present; the main species distinguishing this community from the previous one is vaccinium vitisidaea. – cowberry-dominated. it is characterized by the dominance of vaccinium vitis-idaea and by a lower average number of species (26). 2. regressive stages due to the soil erosion: the marked soil erosion causes a reduction in the arboreal cover to the advantage of the shrubby one. near the typical species of pinewoods grow more heliophilous species linked to thinner communities like carlina acaulis, senecio abrotanifolius and thymus polytrichus. the average number of species rises to 40. all these communities are similar to the association erico carneae-pinetum prostratae zöttl 1951, with a particular reference to the subassociation caricetosum humilis br.-bl. 1939 rhododendron hirsutum-dominated pinewood. it is really different for the dominant role of rhododendron hirsutum in the shrubby layer, for the scanty cover of vaccinium vitis-idaea and for the low floristic richness (17 species) mainly due to the disappearance of the most thermophilous species. the herbaceous layer is sparse and dominated by heather only. this kind of vegetation can only be found on slopes facing northward and can be ascribed to the association rhododendro hirsuti-pinetum prostratae zöttl 1951. pinewoods growing on screes. the presence of lithophilous species make these coenoses similar to the pioneer herbaceous ones growing on early developed soils. two kinds of pinewoods can grow on screes: one is characterized by scrubby pines growing on young surfaces, and the other one represents a former pinewood buried by low energy debris flows. these communities have an uncertain syntaxonomic treatment and can be considered as a transition between athamanto-trisetetum and primary stages of erico-pinetum. 44..55..33..ggrraassssllaannddss (tab. 4) grasslands are very rich in species (the average number of species per relevé is 52). the herbaceous layer is almost continuous but often not very thick, probably because of the low cover value of grasses (mainly festuca nigrescens and sesleria varia) compared to the rosette-shaped plants (plantago alpina, cirsium acaule and carlina acaulis). grasslands include the most acidophilous and the least xerophilous communities in the studied area and can be all regarded as pastures. although all the grasslands share a high cover value of sesleria varia, two main communities, growing on different substrata, can be distinguished; some transition stages can also be observed. poa alpina and festuca nigrescens grasslands. these communities grow on fan gravelly deposits and are the richest in species (up to 68 per relevé). grasses and sedges (sesleria varia, poa alpina, festuca nigrescens, carex sempervirens and 199late holocene environmental evolution ... table 3 synoptic table of the mountain pine woods and scrubs. the synoptic tables point out only the main communities and not those belonging to an inferior rank which are instead relevant as concerns the dynamic aspects. tabella sinottica dei boschi e degli arbusteti a pino montano. le tabelle sinottiche evidenziano solo le comunità principali e non quelle di rango inferiore, che sono invece importanti per gli aspetti dinamici. 200 m. santilli et alii table 4 synoptic table of the grasslands. even though androsace chamaejasmae is widespread it is not present in the table because of its premature disappearance during the vegetative season. tabella sinottica dei pascoli. nonostante la diffusa presenza, androsace chamaejasmae non compare nella tabella per via della sua precoce scomparsa durante la stagione vegetativa. elyna myosuroides) have very high cover values. some species (e.g. luzula multiflora, elyna myosuroides and avenella flexuosa) show a soil acidification and/or an accumulation of organic matter. these coenoses can be included in the class seslerietea albicantis oberd. 1978 corr. oberd. 1990 (mucina et al., 1993) and probably be referred to seslerieto-semperviretum br.-bl. 1926 (alliance seslerion coeruleae br.-bl. in br.-bl. & jenny 1926). however, species belonging to different syntaxa (in particular the acidophilous taxa) can also be present thus making the syntaxonomic and synecological treatments difficult. cirsium acaule and plantago alpina grasslands. these communities grow on the silty deposits in the val paolaccia unit, have a lower floristic richness (30-40 species per relevé) and a less continuous structure, where grasses and sedges play a less important role. the dominant or significant species are cirsium acaule, carex flacca and plantago alpina. the syntaxonomic classification is very difficult in this case, too. carex flacca regressive stage. where the erosion prevails (see fig. 8) grassland species are replaced by other species as tussilago farfara and carex flacca, which become dominant. pine settled over grasslands. even if these communities share many species with the grasslands of silty deposits, the sparse tree layer allows the pine wood species as erica carnea to grow and causes the majority of the heliophilous grassland species to disappear. 55.. eennvviirroonnmmeennttaall eevvoolluuttiioonn ooff tthhee uuppppeerr vvaallllee ddeell ggaalllloo 55..11.. hhoolloocceennee eevvoolluuttiioonn ooff tthhee vvaalllleeyy bboottttoomm the oldest sediments cropping out on the valley bottom are lacustrine deposits belonging to the acqua del gallo unit. the paleolake was buried by a coarsening-upward succession of clays, microturbidites, alluvial and deltaic deposits transported by the fans prograding from the tributary valleys (fig. 12). the basin had already dried up before the middle holocene (e.g. before 4710 ± 90 14c yr b.p.). this phase caused the formation of an ancient flat valley bottom (belonging to the valle della casina unit) now representing inactive portions of some fans (fig. 5; see par. 4.1); its southern part dates back at least to the iron age (2570 ± 70 14c yr b.p.), but it is probably much older (e.g. before 3910 ± 60 14c yr b.p.). later, the northern and southern sectors of the upper valle del gallo had a different evolution. after eroding the northward lacustrine threshold, creek acqua del gallo started an intense regressive erosion process which at first affected the northern sector of the valley (fig. 12). this caused the formation of deep gorges (up to 50 m) in the fans of val mora and valle della casina (and locally in the bedrock), and the dismantling of wide portions of the fans of val bruna and “valle del pizzo aguzzo”, what isolated some still existing parts of the original valley bottom (fig. 5; see par. 4.1). yet a series of important flooding phases temporary interrupted the erosion process at least since the copper age (3910 ± 60 14c yr b.p.) as testified by the val bruna subunit which is embanked in the valley bottom (figs. 5-12-13). the subunit is intercalated by buried soils documenting that it formed in successive stages, separated by significant phases of stability and some changes in the erosion direction of creek acqua del gallo (see terrace (h) in fig. 13). the southern sector of the studied area (fig. 12) was not dissected by erosion until recent years. for this reason, a thick succession of fine deposits originated by sheetfloods (val paolaccia unit) accumulated among the coalescent fans of valle della casina, “valle del 201late holocene environmental evolution ... fig. 12 stratigraphic relations of the upper valle del gallo. an ideal profile was used to show the different units at the same time. schema dei rapporti stratigrafici dell’alta valle del gallo. è stato impiegato un profilo ideale per mostrare contemporaneamente le diverse unità. pizzo aguzzo” and val paolaccia. depositional events, which were originally very frequent, prevented the settlement of vegetation (see section 2 in fig. 9 and appendix i; see par. 4.2.3). meanwhile, the regressive erosion extended southward along the river bed of acqua del gallo isolating distal portions of some fans (e.g. under the val mora road for the valle della casina fan). in the middle ages (1270 ± 70 14c yr b.p.) it reached the val paolaccia unit, favouring the drainage and the reduction of the sedimentation rate. therefore fluvisols started to develop together with a kind of vegetation suitable to adapt to frequent burials (cirsium acaule and plantago alpina grasslands) the features of which show the persistence of vegetation during aggradation. only some parts of the fan surfaces were affected by these changes in the sedimentary activity and in the vegetation. other portions of the fans were still under an active aggradation. the formation of the middle part of the valle della casina fan went on at a high rate, at least till the late roman age (1720 ± 50 14c yr b.p.; fig. 14, tab. 1), when a phase of morphologic stability caused the formation of a soil (buried soil in section 5, figs. 6-14). since the middle ages, debris flows were instead mostly localized close to the fan apex (see buried soils in section 6, figs. 6-14; see par. 5.2) and along the main channel (a in fig. 6), its ramification (b, c, g) and the adjoining sectors (e, f, d), while its most distal part was isolated by the downcutting formed by the main channel, under the val mora road. therefore, on the whole, since the middle ages, the regressive erosion of the valley bottom is responsible for the general stabilization of many surfaces, since debris flows which were locally canalised can no more spread on the entire fan surface. 55..22.. rreecceenntt eevvoolluuttiioonn ooff tthhee vvaallllee ddeellllaa ccaassiinnaa ffaann the dendrochronological reconstruction of the debris flow sequence in the valle della casina (fig. 11) begins at the end of the 19th century because of the young age of the trees. the presence of young forests (100-200 years old) is probably due to the drastic deforestation which occurred over past centuries. the most ancient dated event happened in 1888 and involved area (f) besides the channels and area (e) (fig. 15), where it covered a part of the fan surface currently exposed downhill. later debris flows (in 1927-29 and in 1936-41) interested this area only marginally (fig. 15). the most recent episodes were mostly confined to the main channel (a), where they affected the margin of area (f), and to the secondary channels (b) and (c). the 1978 debris flow represents the most intense episode during which a new channel developed (g in fig. 6). the event, which occurred in 1986, formed the upper part of the terrace (d) (see fig. 14). the main channel (a) of the valle della casina fan constitutes the course of normal drainage, with a maximum capacity able to contain the smaller flows (e.g. 1964 and 1992), the traces of which (damaged trees and terraces) are only visible along the margins. below val mora road, scarps border the main channel so in the lower part of the fan the flows do not have any direct effect outside the river bed and can reach the river acqua del gallo. when the flows exceed the maximum flow rate in the main channel, the secondary channels 202 m. santilli et alii fig. 13 hypothetical succession of events that originated the val bruna subunit and the terrace (h): 1) ancient post-lacustrine valley bottom; 2) first downcutting phase by the river acqua del gallo; 3) dismantlement of a part of the “valle del pizzo aguzzo”fan; 4) formation of a new portion of the “valle del pizzo aguzzo” fan; 5) second downcutting phase by the river acqua del gallo; 6) new flooding on the “valle del pizzo aguzzo” fan; 7) present downcutting by the river acqua del gallo and separation of the terrace (h). ipotetica successione di eventi che avrebbe dato origine alla sottounità della val bruna e al terrazzo (h): 1) antico fondovalle post-lacustre; 2) prima fase di incisione da parte dell’acqua del gallo; 3) smantellamento di parte del conoide della “valle del pizzo aguzzo”; 4) costruzione di una nuova porzione del conoide della “valle del pizzo aguzzo”; 5) seconda fase di incisione da parte dell’acqua del gallo; 6) nuova fase di alluvionamento del conoide della “valle del pizzo aguzzo”; 7) incisione attuale dell’acqua del gallo e separazione del terrazzo (h). (b) and (c) are involved. trees slacken these lateral flows that can spread to larger surfaces, hence they do not reach the river acqua del gallo (e.g. 1927-29, 1953, 1959 and 1978). exceptional flows can sometimes form new courses when they exceed also the maximum flow rate of the secondary channels. in 1978 channel (g) originated in this way. the subsequent restoration of the main channel banks made the lateral channels inactive again. 55..33.. rreellaattiioonnss bbeettwweeeenn ssooiill aanndd vveeggeettaattiioonn aanndd ddyynnaammiicc ooff tthhee eeccoollooggiiccaall ssuucccceessssiioonn soils and vegetation of the upper valle del gallo are, in general, scarcely developed. this is probably due to five principal causes: the relatively recent age of those areas subjected to pedogenesis; the periodic burial affecting some areas; the climatic restriction due to low temperature and scanty rainfall; the effects of human deforestation during the last millennium; the extent of areas subjected to an intense soil erosion. the relations between plant communities and soils allow us to make some considerations. pioneer litophilous communities grow only on calcari-hyperskeletic leptosols. pinewoods do not show soil more developed than leptosols, even at their most advanced stages. the stage characterized by the presence of cowberry on the carex humilis and sesleria varia-dominated pinewoods occurs on humi-rendzic leptosols (calcaric); these soils locally grow under less developed vegetation together with calcaric and calcari-humic leptosols. the presence of a cambisol under a regressive stage of the carex humilis and sesleria varia-dominated pinewood suggests that pinewoods growing on skeleti-calcaric cambisols are the most developed situation found on the fans (a higher evolution degree concerning the woody vegetation can be found only locally on the slopes, out of the fans). grasslands show a close relation between plant communities and soil typologies. for example cirsium acaule and plantago alpina grasslands only occur on calcaric fluvisols while poa alpina and festuca nigrescens grasslands develop only on leptosols or locally on cambisols with a moderate degree of decarbonatation as suggested by the presence of some acidophilous species (see par. 4.5.3.). it is now possible to outline the dynamic succession of soil and vegetation. surfaces formed by different sedimentation and erosion processes are progressively colonized by vegetation and are subjected to pedogenesis as they become sufficiently stable. the ecological succession occurs on two kinds of substrate, both carbonatic, different in the grain size and originated by two sedimentary processes: gravel with a sandy matrix deriving from debris flows (valle della casina unit); silts and fine sands without skeleton deriving from sheetfloods (val paolaccia unit). a third subordinate kind of parent material is constituted by coal masses from charcoal pits. the dynamic succession on a gravelly substrate (fig. 16) starts with plant communities collected in the athamanto-trisetetum grown on calcari-hyperskeletic leptosols. under geomorphological stability, a pine scrub settles and discontinuous mosaic-like horizons o and a grow up connected with pioneer vegetation. the further soil evolution involves an increase in the fine fraction and the development of a thin horizon a (calcaric leptosols). when the mass of organic matter and the decarbonatation become significant, soils pass to a stage of calcari-humic leptosols, existing until a mollic horizon develops (humi-rendzic leptosols (calcaric)). locally a bw horizon sometimes evolving 203late holocene environmental evolution ... fig. 14 block-diagram of the hydrographic left side of the main channel (a in fig. 6) of the valle della casina fan showing the position of sections 5 and 6 and of the buried charred wood (star) dated 1720 ± 50 14c yr b.p. (tab. 1). block-diagramma del lato sinistro idrografico del canale principale (a in fig. 6) del conoide della valle della casina che mostra la posizione delle sezioni 5 e 6 e del tronco carbonizzato sepolto (asterisco) datato 1720 ± 50 anni 14c b.p. (tab. 1). into a cambic horizon (skeleti-calcaric cambisols), can originate. at the same time the development of vegetation brings about an increase in the number of species and in the ground cover until carex humilis and sesleria varia-dominated pinewoods develop, where the first acidophilous species appear. the progressive acidification of the upper horizons causes an increase in the acidophilous species, the decrease in the basiphilous ones and an increase in the tree layer and in the erica carnea cover, until the species richness decreases to the advantage of vaccinium vitis-idaea (the cowberry-dominated stage). the latter is the most developed stage of vegetation found, which probably took place after a few hundred years. the rhododendron hirsutum-dominated pinewood is mainly limited to the northward exposure. all the remaining vegetation typologies represent regressive stages or secondary vegetation. the burial caused by debris flows brings the pine-forest back to athamanto-trisetetum with a tree layer; this is probably susceptible to a rapid development due to the litter supplied by the tree cover. the surface soil erosion makes the succession regress to less developed stages because of the removal of the upper horizons and the progressive crop out of parent material; the pine-forest is thinned out and the number of heliophilous species increases. on the contrary grasslands are to be considered as secondary vegetation deriving from pine-forests deforestation. the ecological succession on a silty substrate (fig. 16) is periodically interrupted by centimetric burials caused by sheetfloods. however, the soil evolution is connected to the frequency of burial episodes, depending on the closeness of the downflow direction. soils are calcaric fluvisols, periodically rejuvenated, without a meaningful decarbonation and an organic matter accumulation. the vegetation dynamics stops to a stage of blocked evolution (cirsium acaule and plantago alpina grasslands). the morphological attributes of the dominating species indicate that this community seems to “float” on a substrate in periodic aggradation; in fact carex flacca is a stoloniferous plant while plantago alpina and cirsium acaule develop tap-roots up to 50-cm long. this reaction of the vegetation causes the common radical pedoturbation. on the contrary, where erosion is intense, substitution communities prevail (carex flacca regressive stage). whenever grasslands disappear pinus montana forms a tree layer again. 66.. ccoonncclluussiioonn during the holocene, the upper valle del gallo experienced a series of intense transformations that progressively and quickly transformed the environmental setting that became established after the retreat of the würmian glaciers. complex and still unclear erosive and depositional cycles of glacial origin formed thresholds that originated a lake, although this is a pass zone, where outflows should therefore have been facilitated. environments originally poor or without vegetation, supplied an ideal substrate for the weathering and denudation processes of the slopes, originating huge amounts of debris that water could easily mobilize and transport to the lacustrine basin. its width and depth 204 m. santilli et alii favoured a pelagic terrigenous sedimentation, than in a few thousand years progressively evolved into an alluvial and deltaic environment characterized by shallow water and finally a terrestrial environment dominated by fans mostly formed by debris flow processes. vegetation adapted finding a balance with the environmental dynamics, characterized by a high instability of the slopes causing erosion and covering processes that often determine ecological situations with a blocked or slowed down evolution. the valley setting was finally modified by human action. because of the complexity and the interaction of the various ecological components, the study of this kind of environment necessarily demanded an interdisciplinary approach. the several methods used span various temporal intervals and space scales and have different resolution power, but each of them contributed in an effective way to explain every single aspect of the environmental evolution of the examined territory, allowing the final integration and synergy of the different results obtained. this route forms in a more and more detailed way for the recent times: the geomorphological and stratigraphic researches, allowed us to reconstruct the main evolutionary stages of the whole territory during the holocene and to identify some factors controlling the ecological successions; the study of the soils and vegetation has allowed us to clarify the relations existing between the various environmental components and the adaptations to the dynamics of the geomorphological and sedimentary processes occurred during relatively recent times; finally, the dendrogeomorphological fig. 15 scheme showing area (f) and the different age sections composing it. below this area a buried soil (section 19 in fig. 6) and a buried stump in position of life were found (star) (santilli & pelfini, 2002). schema mostrante l’area (f) e le porzioni di differente età che la costituiscono. sotto quest’area è stato inoltre trovato un suolo sepolto (sezione 19 in fig. 6) e un tronco sepolto in posizione di vita (asterisco) (santilli & pelfini, 2002). study has allowed us to know the precise dating and the extent of every single debris flow that, starting from the end of the 19th century, affected one of the fans. the environmental complexity of the upper valle del gallo must be deepened further on. in spite of the great amount of data and information collected up to now, new stratigraphic sections, especially relevant to the lacustrine succession, would be necessary since they could clarify the valley evolution starting from the late-glacial period and the influence of the successive alternate phases of climatic deterioration and improvement; further surveys should concern the taxonomic position of the mountain pine, the widespread superficial erosion of pinewoods and the important role of the anthropic influence, which has been up to now only partially documented. we want to emphasize the importance of an integrated approach of different disciplines to the studies on the environment. the efforts necessary to carry out interdisciplinary studies often must be restricted to small areas; however starting from local events it is possible to make comparisons and to extrapolate results that can refer to bigger areas or be applied on a regional scale. researches carried out up to now constitute therefore a good starting point for the study of the peculiar environment of the vale del gallo, to which an elevated naturalistic value to be preserved and exploited is acknowledged. the research has been carried out with the cofinancing of murst-cofin 40%-1999 project: movimenti di massa come indicatori di cambiamenti climatici dal tardiglaciale ad oggi. national responsible prof. m. panizza, local responsible prof. g. orombelli. aacckknnoowwlleeddggeemmeennttss the authors wish to thank prof. g. orombelli of the university of milano-bicocca, for the critical revision of the manuscript, the parco nazionale dello stelvio for authorising researches in its territory and aem milano for supplying the climatic data. rreeffeerreenncceess agostoni u. (1923) i giacimenti ferriferi dell’alta valtellina. in “la miniera italiana”, published on the journal “valtellina”, issues of april 11th and 18th, 1923. alestalo j. (1971) dendrochronological interpretation of geomorphic processes. societas geographica fenniae, fennia n. 105, pp. 140. baumann f. & kaiser k.f. (1999) the multetta debris fan, eastern swiss alps: a 500-year debris flow chronology. arctic, antarctic, and alpine research, vol. 31, n. 2, pp. 128-134. berra f. (1994) stratigrafia e paleogeografia del triassico superiore delle falde ortles e quattervals (australpino superiore) in lombardia. doctorate thesis in earth sciences, istituto di geologia, università di milano, pp. 146. bonsignore g., borgo a., gelati r., montrasio a., potenza r., pozzi r., ragni u., & schiavinato g. (1969) note illustrative della carta geologica d’italia alla scala 1:100.000, foglio 8 “bormio”. roma, pp. 123. borgonovo g. 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(1960) il paesaggio vegetale della provincia di sondrio. flora et vegetatio italica, mem. n. 3, ed. gianasso, sondrio, pp. 132. govi. m., mortara. g., marchi l. & turritto o. (1994) ricerche sulle colate detritiche torrentizie (debris flow) in ambiente alpino. cnr-gndci, linea 1, rapp. 1990-91, pp. 405-420. govi. m., mortara. g. & sorzana p. f. (1985) eventi idrologici e frane. estratto da: “geologia applicata e idrogeologia”, vol. xx, parte ii, bari, pp. 359375. heikkinen o. (1994) using dendrochronology for the dating of land surfaces. in “dating in exposed and surface contexts” (ed. c. beck), university of new mexico press, albuquerque, pp. 213-235. isss-isric-fao (1998) world reference base for soil resources. world soil resources reports, 84, fao, roma. leoni b. (1953a) l’estrazione e la lavorazione del ferro in valtellina durante l’epoca medioevale. valtellina e valchiavenna, rassegna economica della provincia di sondrio, n. 11, novembre 1953, pp. 13-14. leoni b. (1953b) notizie sull’estrazione e lavorazione del ferro in valtellina tra il xvi e il xx secolo. valtellina e valchiavenna, rassegna economica della provincia di sondrio, n. 12, dicembre 1953, pp. 22-23. martina e. (1954) la geologia dell’alta valle di fraele. thesis in geology, istituto di geologia, università di milano. minghetti p. (1996) analisi fitosociologica delle pinete a pinus mugo turra del trentino (italia) . documentes phitosociologiques, n.s., vol. xvi, camerino, pp. 461-503. mortara g., ceriani m. & laffi r. (1994) l’evento alluvionale del 22 luglio 1992 nella conca di bormio in alta valtellina. quaderni di studi e di documentazione n. 17, suppl. geam, cnr, pp. 25-33. mucina l., grabherr g. & wallnöfer s (1993) die pflanzengesellschaften österreichs. iii, wälder und gebüsche, fischer, jena, stuttgart, newyork. nichols g. 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(1973) la vegetazione. in “le alte valli dell’adda e dello spöl, un ambiente da conservare”, a cura dell’assessorato economia montana e foreste. regione lombardia. pp. 77-94. polloni g, ceriani m, crosta g, lauzi s, padovan n, (1991) rainfall and soil slipping events in valtellina. in bell dh (eds.). landslides. proc. vi int. symposium on landslides. balkema, rotterdam: 183-188. pozzi r. & giorcelli a. (1960) memoria illustrativa della carta geologica (scala 1:35.000) della regione compresa fra livigno ed il passo dello stelvio (alpi retiche). boll. serv. geol. it., vol. 81, serie g, pubbl. n. 131, milano, pp. 72. saibene c. (1973) lineamenti di geomorfologia. pp. 69-76 in le alte valli dell’adda e dello spöl, un ambiente naturale da conservare. a cura dell’assessorato all’economia montana e foreste. regione lombardia, pp. 109. salvador a. ed. (1994) international stratigraphic code. second ed., the geological society of america. sanesi g. (1977) guida alla descrizione del suolo. progetto finalizzato conservazione del suolo, c.n.r., firenze, pp. 157. santilli m, (2000) storia ed evoluzione dei conoidi dell’alta valle del gallo (alta valtellina-sondrio). studio geomorfologico, stratigrafico, dendrocronologico, pedologico e vegetazionale. thesis in natural sciences. dipartimento di scienze della terra, università di milano, italy, 273 pp. santilli m, pelfini m (2002) dendrogeomorphology and dating of debris flows in the valle del gallo, 206 m. santilli et alii central alps, italy). dendrochronologia 20 (3), pp. 269-284. shroder j.f. (1980) dendrogeomorphology: review and new techniques of tree-ring dating. progress in physical geography 4, pp. 161-188. strunk h. (1995) dendrochronologische methoden zur ermittlungen der murfrequenz und beispiele ihrer anwendung. regensburg: s. roderer verlag, pp. 196. stuiver m., reimer p. j., bard e., beck j. w., burr g. s., hughen k. a., kromer b., mccormac f. g., plicht j. & spurk m. (1998) intcal98 radiocarbon age calibration 24,000-0 cal bp. radiocarbon 40, pp. 1041-1083. van der maarel e. (1979) transformation of coverabundance values in phytosociology and its effects on community similarity. vegetatio, 39 (2), pp. 97-114. zazzi s. (1982) per una storia delle miniere di val fraele e dei forni da esse alimentati. notiziario n. 30, dicembre 1982, banca popolare di sondrio, pp. 78-83. aappppeennddiixx ii ((ddeessccrriippttiioonn ooff tthhee ssttrraattiiggrraapphhiicc sseeccttiioonnss)) sseeccttiioonn 33 - aaccqquuaa ddeell ggaalllloo uunniitt (fig.7). from the bottom upwards: 0-2,5 m: grey (2,5y 5/1) and brown (10yr 5,5/3) clayey deposits with a flat parallel lamination, made of thin massive clay laminas, less than 1-mm to 3mm thick, alternating with subordinate silty clay and silt levels. very fine grey and well sorted sand laminas are widespread too; 2,5-4,5 m: deposits mostly clayey and laminated, yellow reddish and analogous to the previous ones, but showing on average thicker laminas. locally deposits loose this flat parallel lamination and sediments assume a “mottled” aspect due to the different colors according to the grain size 4,5-5 m: centimetric layers with a flat parallel lamination mainly composed of brown clay laminas and subordinate intercalations of silt and very fine grey sands; 5-5,8 m: dark grey sand layer, the structure of which alternates between middle-sized and fine sands in a wavy parallel lamination, with subordinate millimetric grey-brown silty levels. in the upper part a layer with a low-angle cross lamination can be observed, then assuming a climbing style and gradually reconstituting the wavy parallel lamination and then again the flat parallel one; 5,8-8 m: laminated deposits mostly clayey, brown reddish, with subordinate intercalations of very fine sands 2,5y 5/2; 8-12 m: in this layer the first gravel levels can be found. these deposits tend to have a normal gradation layer, some-centimetres to 1-2-decimetres thick. each layer is composed at its base of variable thickness centimetric levels of fine and middlesized gravel with loose centimetric clasts in clear contact, often of erosive type, on the underlying finer sediments; towards the top the layer structure gradually passes to grey middle-sized and fine sands, to silt and brown reddish silty clay, in a wavy subparallel lamination at intervals little evident; 12-15,5 m: centimetric alternations of fine sands, middle-sized sands, gravelly sands and gravel with subordinate silty levels that, quantitatively, tend to reduce towards the top; 15,5-18,5 m: unselected gravelly and clast-supported sediments alternated with lens and intercalations of sands and silt sometimes containing gravel with matrix support (sometimes reddish). a rough stratification, locally passing to a cross stratification, can be observed; 18,5-22 m: proceeding towards the top unselected gravel sediments with a clastic support without sedimentary structures gradually become prevalent. at the top of the scarp there is a soil (humi-rendzic leptosols (calcaric)). sseeccttiioonn 3399 - vvaall ppaaoollaacccciiaa uunniitt (fig. 9) sequence of silt and sand deposits lacking in skeleton, organised in little differentiated sedimentary sublevels and laying upon a buried soil developed on the underlying gravel. +1-0, 0-1 cm: horizon o (oi + oe); 1-7 cm: horizon a, light grey 2,5y 5/2, with a silty loam texture and a little marked fine granular structure; numerous plant remains, many thin and middlesized roots, a clear wavy boundary, and a high effervescence. analytical data: ph 7,8, organic c 24,8 g/kg; 7-18 cm: horizon c composed of massive grey sands, 2,5y 5/2, with brown variegations,10yr 4/2, woody subhorizontal roots up to 1 cm in diameter; 18-37 cm: middle-sized to fine sands as above, well selected, but with a dark brown tonality and a clear wavy boundary; little coal fragments are widespread at the base; 37-49 cm: middle-sized grey sands with thin discontinuous brown lens including coal fragments; coal remains are scattered inside the level, too; 49-53 cm: yellow-ochre sandy silt; clear boundary; 53-57 cm: middle-sized to fine brown-grey sands with an evanescent lamination and a clear lightly wavy boundary; sparse coal fragments; 57-60 cm: horizon ab, brown 10yr 3/2, with a poor skeleton, a well marked fine granularpolyedric subangular structure, a silty loam texture, thin and middle-sized common roots, a wavy abrupt boundary and a high effervescence. analytical data: ph 8,0, organic c 34,3 g/kg. this buried soil dates back to 1270 ± 70 14c yr b.p. (tab. 1); 60-65 cm: horizon c1' composed of incoherent gravel with clasts up to 10 cm with the support of a sandy middle-sized to coarse matrix and fine gravel, grey brown 10yr 5/3, with very thin common roots, a gradual wavy boundary, a high effervescence and unaltered or only lightly altered pebbles; 65-95 cm: rough stratified gravel alternating between clastic support and matrix support up to 10 cm big, with a coarse sandy matrix, subangular pebbles, sometimes subrounded. the horizon shows a reddish matrix and reddish patinas on pebbles that at some levels form rather wide pellicles. roots are absent. 95-250 cm: fine gravel with matrix support alternating with sand lens lightly altered; in this case too the matrix of the gravelly levels shows reddish patinas that harden the sediment. 207late holocene environmental evolution ... sseeccttiioonn 4499 - vvaall ppaaoollaacccciiaa uunniitt (fig. 9) sequence of sandy and silty deposits lacking in skeleton, organised in sedimentary differentiated sublevels and laying upon a buried soil developed on the underlying gravel. 0-10 cm: horizon a, dark brown, having a weakly marked fine granular structure, a sandy loam texture, abundant roots and a clear wavy boundary; 10-30 cm: bioturbated massive fine sands, light grey with ochre tones, 2,5y 5/2; 30-33 cm: grey middle-sized to fine sands; 33-40 cm: yellowish silty fine sands, 2,5y 5/2, having a weakly marked fine polyedric subangular structure and sparse thin roots; 40-45 cm: middle-sized laminated and well selected sands, 2,5y 4/2; 45-51 cm: sandy silt with fine sand, brown-yellowish, 2,5y 5/3; 51-56 cm: middle-sized to fine laminated yellowish sands, 2,5y 5/2; 56-66 cm: massive fine sands with a weakly marked lamellar structure, grey, 2,5y 4/2, with sparse roots and a clear boundary; 66-75 cm: fine sand sandy silt, yellow-brown, 10yr 5/3, having a moderately marked middle polyedriclamellar structure; 75-93 cm: yellowish fine sand sandy silt, 2,5y 5/3, having a weakly marked polyedric-lamellar structure; 93-101 cm: grey middle-sized sands, 2,5y 4/2; 101-123 cm: weakly sandy silt with fine sand, with colors zoned between yellow and yellow-brown, and a very weakly marked lamellar structure; 123-129 cm: middle-sized grey sands; clear boundary; 129-140 cm: yellow-brown weakly sandy silt with fine sand, a weakly marked lamellar structure and a clear boundary; 140-145 cm: horizon ab 10yr 4/3, with a well marked middle polyedric angular structure, a clayey silty loam texture, a high effervescence, a poor skeleton on the surface, more abundant at the base of the horizon, where it gradually passes to the underlying horizon. analytical data: ph 8,0, organic c 28,5 g/kg. this buried soil dates back to 2570 ± 70 14c yr b.p. (tab. 1); 145-160 cm: altered gravel in a sandy matrix 10yr 5/4 altered too; patinated pebbles altered on the surface, patinas having the same color as the soil, little marked fine granular structure. sseeccttiioonn 22 - vvaall ppaaoollaacccciiaa uunniitt (fig. 9) sequence entirely composed of sandy and silty fine deposits, without skeleton, organised in sedimentary sublevels. the first 90 cm differ from the remaining part because of the presence of buried horizons and organic matter. 0-10 cm: horizon ac little pedogenized composed of grey massive fine sands, 10yr 5/1,5, with very poor roots and a wavy boundary; 10-14 cm: horizon ab composed of silty sands 10yr 4/2, having a moderately marked middle-sized to fine polyedric structure and thin sparse roots; 14-18 cm: massive grey fine sands 10yr 5/1; clear wavy boundary; 18-26 cm: horizon ab' composed of fine silty sands 10yr 4/2, with brown variegations explainable as the result of radical bioturbations; well marked middle-sized to fine polyedric structure, with sparse roots, sometimes woody too, with a subhorizontal course, an irregular boundary with pedoturbation of biological origin going down to the underlying levels (up to 60 cm); 26-30 cm: massive grey fine sands as above, 10yr5/1, with a light wavy boundary; 30-34 cm: horizon ab'' composed of lightly silty fine sands 10yr 4,5/2, with a weakly marked middlesized to fine polyedric structure and a lightly wavy boundary; 34-39 cm: lens of grey sand as above, 10yr 5/1; 39-46 cm: horizon ab''' composed of fine silty sands 10yr 4,5/2, with a weakly marked medium-sized granular structure and a clear wavy boundary; presence of partially decomposed needles; 46-70 cm: grey massive fine sands, alternating with fine silty-sandy ochre levels, subhorizontal and lightly wavy; clear boundary; 70-90 cm: ochre-yellowish massive sandy silt 2,5yr 5/3, with variegations composed of small but long empty spaces sometimes filled with decomposing dark roots; in the upper part a dark brown level rich in very little coal fragments (71-72 cm) and an ochre level with sporadic millimetric coal fragments (72-77 cm) can be observed; 90-400 cm: yellowish sandy silt alternating with subordinate centimetric levels of mainly massive grey silty fine sands, with little clear-cut lamination; locally (about 130 cm) there are laminas with a normal gradation. it is a monotone succession, totally lacking in organic elements. pedogenized buried horizons have not been identified. between 200 and 400 cm sparse little shells of gastropods can be found. 208 ms. ricevuto il 23 ottobre 2001 testo definitivo ricevuto il 10 settembre 2002 ms. received: october 23, 2001 final text received: september 10, 2002 m. santilli et alii imp.orombelli& osservazioni sul significato dei termini lgm (umg), tardoglaciale e postglaciale in ambito globale, italiano ed alpino giuseppe orombelli 1 , cesare ravazzi 2 & maria bianca cita3 1dipartimento di scienze dell’ambiente e del territorio, università di milano bicocca, giuseppe.orombelli@unimib.it 2cnr – istituto per la dinamica dei processi ambientali, sezione di milano. cesare.ravazzi@idpa.cnr.it 3dipartimento di scienze della terra, università di milano, maria.cita@unimi.it. riassunto: g. orombelli, c. ravazzi, m.b. cita, osservazioni sul significato dei termini lgm (umg), tardoglaciale e postglaciale in ambito globale, italiano ed alpino. (it issn 0394-3356, 2005). il presente lavoro intende esaminare il significato e l’impiego di alcuni termini dal forte segnale climatico in uso nella stratigrafia del quaternario continentale: last glacial maximum (ultimo massimo glaciale); lateglacial (tardoglaciale, questa dizione è da preferirsi a tardiglaciale), postglacial (postglaciale). il termine lgm ha origine da una sintesi degli studi sulle variazioni del livello marino, delle temperature della superficie del mare (sst) ottenute dalle associazioni dei foraminiferi planctonici e dei rapporti isotopici ottenuti dai foraminiferi bentonici. questi indicatori forniscono evidenze concordanti sull’esistenza, nell’ambito dell’ultima glaciazione, di un intervallo in cui i ghiacciai continentali raggiunsero il loro massimo volume integrato. il termine ha quindi una connotazione globale e come tale non può essere definito sulla base di indicatori di valore regionale o locale. le manifestazioni locali dell’evento lgm possono essere diverse nelle diverse aree del pianeta. in base ai più recenti dati sul minimo assoluto raggiunto da livello del mare durante il mis (marine isotopic stage) 2, il lgm sarebbe compreso tra 19 e circa 30 mila anni cal bp. sussistono tuttora alcune discrepanze tra i diversi indicatori sulla fase iniziale dell’intervallo. recentemente lgm è stato usato liberamente anche in geologia glaciale per indicare il limite più esterno raggiunto dai margini glaciali durante l’ultima massima avanzata. anche con questa accezione (che è informale) gli autori si riferiscono all’ultimo degli eventi glaciali, delimitato cronostratigraficamente nel late wisconsin / late weichselian / late würm, e si limitano a includerne la fase di massimo, escludendo le fasi di sviluppo e di decadenza. si sottolinea peraltro la valenza cronologica globale del termine lgm. nella scala cronostratigrafica regionale è altresì codificato l’impiego del würm come piano corrispondente all’espressione dell’ultima glaciazione nelle alpi, con le prime fasi datate intorno a 105 ka bp, mentre il sottopiano würm superiore comprende le fasi di avanzata, di massimo e di ritiro glaciale dell’ultimo evento verificatosi tra 30 e 11.5 ka cal bp. il termine tardoglaciale è impiegato con significati diversi, talora comprendendo le fasi della deglaciazione a scala locale, talora indicando l’intervallo di tempo tra l’inizio dell’ interstadio groenlandese 1 e l’inizio dell’olocene (da 14.7 a 11.5 ka cal bp), talora, infine per indicare l’ultima transizione climatica che si estende dalla fine del lgm all’inizio dell’olocene, con significato globale. gli scriventi ritengono che anche il tardoglaciale debba essere connotato da criteri stratigrafici a scala globale. il postglaciale è termine informale, usato con vari significati, e quindi privo di un definito contenuto cronologico e/o stratigrafico. abstract: g. orombelli; c. ravazzi, m.b. cita, on the significance of the terms “lgm”, “lateglacial” and “postglacial” at a global and local scale. (it issn 0394-3356, 2005). the significance of the terms last glacial maximum (lgm), lateglacial, and postglacial, used for late quaternary time intervals with a strong climatic signature, is critically analyzed. the term lgm originated thirty years ago after a synthesis of global evidences for a time interval of maximum integrated ice volume, reached during the last glaciation. the relevant proxies are records of the last ice-volume equivalent minimum sea level, of the isotopic oxygen composition (last maximum δ18 o values) of benthic foraminifera and of the sea surface temperature (sst) estimated on planktonic foraminiferal populations. the global signature of the lgm cannot be reliably recorded by local glacial maxima or temperature minima, and the local expressions of the lgm event in the different parts of the world can be well diverse and asynchronous. the most recent datings of the lgm sea-level low stand constrain this interval between 19 and 30 ka cal bp. several glacial geologists employed the term lgm in a broad, informal sense to identify the most external drift limit reached by glaciers during the last maximum advance within the late wisconsin / late weichselian / late würm. the term lgm is used, internationally, to refer to the maximum phase of the last global event of maximum ice volume, and therefore a definition based on local rock units is questionable. the use of the term lgm to refer to local stratigraphic units or climatic events is misleading and should be abandoned. the chronostratigraphic regional definition of the würm stage in the alps, and of its substages is internationally agreed. the würm stage is the alpine chronostratigraphic expression of the last glaciation, with first events recently dated to 105 ka bp. the late würm indicates the last event of major glacial advance within the last glaciation, including the growth, the maximal phase and the deglaciation, occurred between 30 and 11.5 ka cal bp. the term lateglacial is currently used with different significances, including: (i) the time interval of local deglaciation; (ii) the interval between the onset of greenland interstadial 1 and the holocene beginning (i.e. 14.7 to 11.55 ka cal bp); (iii) the transition between the lgm and the holocene, considered at a global scale, i.e. starting at the lgm end and terminating at the beginning of the holocene. we are in favor of a globally valid and accepted definition. finally, the term postglacial has been used informally with different meanings, and has no precise stratigraphic and/or chronological position. parole chiave: nomenclatura stratigrafica, ultimo massimo glaciale, würm, tardoglaciale, postglaciale. keywords: stratigraphic nomenclature, last glacial maximum, würm, lateglacial, postglacial. il quaternario italian journal of quaternary sciences 18(2), 2005 147-155 148 g. orombelli, c. ravazzi & m.b. cita 1. premessa la stratigrafia del quaternario da sempre ha presentato problemi, sia teorici sia nell’uso pratico. l’intervallo di tempo geologico a noi più prossimo si differenzia dai precedenti per la quantità e la qualità delle testimonianze geologiche, paleobiologiche e paleoambientali lasciate e i criteri stratigrafici normalmente usati si adattano con difficoltà allo studio e classificazione dei sedimenti quaternari, in modo particolare di quelli continentali. vi è addirittura incertezza, attualmente, nella definizione del quaternario e dei suoi limiti e nella sopravvivenza stessa del termine formale (p i l l a n s , 2004; p i l l a n s & n a i s h , 2004). secondo gibbard (2004) ciò è anche dipeso dall’aver consentito che si radicasse nell’uso una terminologia, senza che fosse appropriatamente definita. e questo atteggiamento continua tutt’ora, con l’introduzione e l’uso di termini “stratigrafici o quasi-stratigrafici …non o mal definiti, quali last glacial maximum, heinrich event, ecc.” a questo proposito, nel volume 17(1) de “il quaternario” è apparsa la nota “definizione di alcuni termini in uso nella cartografia dei depositi quaternari continentali in ambito alpino”, a firma di bini e altri (2004). poiché tale nota intende avviare un dibattito per “fare chiarezza sul significato dei termini, in modo che chi li utilizza o li affronta abbia un quadro di riferimento il più possibile chiaro ed univoco”, interveniamo con alcune osservazioni e puntualizzazioni. intendiamo esaminare l’impiego e il significato dei termini discussi o citati nella nota, “last glacial maximum (lgm)”, “postglaciale”, “pre last glacial maximum (pre-lgm)”, “tardiglaciale”, in ambito globale e a scala regionale. in questa sede non intendiamo, invece, intervenire sulle problematiche del rilevamento e delle unità stratigrafiche utilizzate nella cartografia dei depositi continentali quaternari in ambito alpino. la sigla ka 14c bp indica un’età radiocarbonica non calibrata espressa in migliaia di anni bp, mentre la sigla ka cal bp indica un’età calibrata e/o calendariale espressa in migliaia di anni bp. per le calibrazioni è stato impiegato il programma calib 5.0 (stuiver & reimer, 1986-2005). 2. last glacial maximum (lgm): origine del termine l’espressione last glacial maximum, successivamente abbreviata in lgm, si è diffusa a partire dagli anni ’70, quando, nell’ambito dei progetti climap e specmap, si è raggiunta una “grande sintesi” a sostegno della teoria orbitale dei cambiamenti climatici, sulla base della combinazione di: (i) dati sulle variazioni del livello marino, basati sulla datazione radiometrica di coralli; (ii) dati sulla temperatura della superficie del mare (sst) dedotta dalle associazioni a foraminiferi planctonici (iii); dati isotopici sulle variazioni del volume dei ghiacci continentali, ottenuti dai foraminiferi bentonici ( cronin, 1999). così l’espressione, con iniziali minuscole, compare nel titolo della pubblicazione conclusiva: climap project members (1981) – seasonal reconstruction of the earth’s surface during the last glacial maximum. in tale contesto, questa dizione non è usata, quindi, per alludere ad una condizione di massima espansione areale dei ghiacciai in un’area glacializzata, ma intende invece riferirsi all’ultima fase di massimo volume globale dei ghiacci sui continenti e di minimo livello del mare, in cui si è venuta a trovare la terra intorno a 18 mila anni 14c bp. contemporaneamente, negli studi connessi, volti a valutare l’estensione, il volume ed i caratteri delle grandi calotte glaciali e dei ghiacciai montani durante l’ultima glaciazione, ed in particolare nella sua ultima fase di acme (si veda ad esempio il volume di denton e hughes, 1981 – the last great ice sheets), si impiegano i termini late wisconsin/late weichselian/late würm, con significato cronostratigrafico regionale, per indicare i complessi deposizionali glaciali, deposti tra circa 22-25 e 10 ka 14c bp. nel volume curato da šibrava, bowen e richmond (1986) quaternary glaciations in the northern hemisphere, ricorrono con significato cronostratigrafico i termini late wisconsin (25-10 ka 14c bp), late weichsel ed altri, con caratteri regionali. ove il controllo cronologico è adeguato, le fasi di massima avanzata glaciale all’interno di queste suddivisioni risultano spesso, anche regionalmente, non sincrone tra loro e con la stratigrafia isotopica marina (fullerton & richmond, 1986). secondo quest’ultima si distinguono, nell’ultimo maggiore completo ciclo climatico (interglaciale/glaciale/ interglaciale), gli stadi isotopici marini (mis) 1, 2, 3, 4, 5 (5a, b, c, d, e) e nell’ambito dello stadio 2, compreso tra 12 e 24 ka cal bp (martinson et al., 1987), viene raggiunto il picco più negativo tra 17 e 19 ka cal bp. martinson et al. (1987) non usano il temine lgm. sempre secondo questi autori, lo stadio 2 è compreso tra i punti intermedi delle transizioni che lo delimitano e al suo interno vengono distinti i sottostadi: 2.2 (17.850 – 19.220 a cal bp); 2.21 (19.220 – 23.170 a cal bp); 2.23 (23.170 – 23.930 a cal bp). peraltro i limiti cronologici degli stadi isotopici marini sono stati successivamente modificati. ad esempio, nella curva δ18 o relativa ai foraminiferi bentonici nelle carote v1930/v19-28 (shackleton, 2000), le età dei punti intermedi delle transizioni che delimitano il mis 2 sono rispettivamente 13 e 29 ka cal bp, anziché 12 e 24 ka cal bp. 3. lgm: uso e definizione vent’anni dopo climap, il programma epilog (mix et al., 2001) si è proposto di fare il punto sull’avanzamento delle conoscenze paleoclimatiche relative al lgm, nonché di proporre uno standard climatoe cronostratigrafico per risolvere conflitti di collocazione cronologica e di intepretazione paleoclimatica ottenute con metodi diversi. lgm è uno dei due estremi dell’ultimo ciclo glaciale-interglaciale e rappresenta l’intervallo più recente nel quale i ghiacciai continentali raggiunsero il loro massimo volume integrato, nell’ambito dell’ultima glaciazione (mix et al., 2001). durante questo intervallo di tempo il clima mantenne condizioni di relativa stabilità, ovvero non si sono registrate ampie variazioni su scala millenaria quali quelle che caratterizzano, invece, lo stadio 3 (mix et al., 2001; chappell, 2002). variazioni nel δ18 o nei gusci di foraminiferi planctonici e bentonici, nelle bolle d’aria sigillate nel ghiaccio, nell’acqua interstiziale dei sedimenti oceanici, nonchè la documentazione delle curve del livello del mare, rappresentano i principali proxy data utilizzati per la documentazione stratigrafica del lgm, mentre “i massimi glaciali o le valutazioni di minimi termici locali” (relativi a specifiche aree della terra) “non rappresentano un valido indice del massimo glaciale integrato a livello globale (globally integrated glacial maximum) (mix et al., 2001). la migliore stima di tale massimo glaciale integrato si desume dalle curve di livello del mare equivalente al volume dei ghiacci, che si ottengono previa eliminazione degli effetti isostatici locali, e dai valori δ18 o nei foraminiferi bentonici ” (mix et al., 2001). ne segue che: 1) una definizione del lgm non può essere data sulla base di indicatori di valore regionale o locale; 2) le manifestazioni locali dell’evento lgm possono essere diverse nelle diverse aree del pianeta, compresa la possibile diacronia delle avanzate glaciali considerate a scala locale. per ragioni pratiche, soprattutto nelle aree in cui il record geologico non contiene i proxy data sopra menzionati e per gli scopi della cartografia geologica, è stata proposta anche una definizione cronologica (cronozona) del lgm. mi x et al. (2001) propongono i seguenti limiti per la cronozona lgm: 19-23 ka cal bp (16–19,5 ka 14c bp). questa opzione è basata sul lowstand del livello del mare indicato da yokoyama et al. (2000), cioè un intervallo di 3000-4000 anni di lowstand a –135 m in australia. tuttavia, come si vedrà nel paragrafo successivo, questo dato non è sostenuto dalle evidenze più recenti sulle variazioni del livello del mare. viene anche indicata una seconda opzione, che corrisponde ad una forchetta leggermente più ampia (18-24 ka cal bp; 15–20,4 ka 14c bp). sarnthein et al (2003), su base isotopica, suggeriscono una cronozona lgm leggermente più recente: 18-22 ka cal bp. 3.1. lgm e livello del mare inversamente correlato al volume integrato dei ghiacci continentali è il livello del mare: le curve relative alle variazioni del livello del mare (ice-volume equivalent sea level) negli ultimi 135.000 anni (che includono per intero l’ultimo grande ciclo climatico) mostrano un minimo assoluto compreso tra circa 30 e 19 ka cal bp. se lgm è definito dal periodo di massimo volume globale di ghiaccio terrestre, allora questo intervallo è durato circa 10.000 anni, cioè più a lungo dell’intervallo usualmente dedotto dal record isotopico dei foraminiferi bentonici (lambeck e chappell, 2001). secondo lambeck et al. (2002) il volume di ghiaccio continentale si avvicina al suo massimo valore intorno a 30.000 cal bp e rimane circa costante per 11.000 anni sino a 19.000 cal bp. l’ingresso nel lgm è caratterizzato da una caduta del livello del mare di circa 50 m in poche migliaia di anni (fig. 1), l’uscita da una rapida risalita iniziale di 15 m in circa 500 anni, seguita da più lenta risalita nei successivi 2500 anni. segue quindi una rapida risalita di 15 mm/a tra 16 e 9 ka cal bp, interrotta tra 12,5 e 11,5 ka cal bp da un livello stabile durante il dryas recente. pertanto, lambeck et al., 2002, definiscono “the onset of the lgm as the time sea levels first approached their minimum levels at about 30,000 years ago”. in base a questa definizione, lgm avrebbe avuto una durata di circa 10.000 anni e includerebbe sia la culminazione dello stadio 2 che il suo inizio, al limite con lo stadio 3. e’ auspicabile che nei prossimi anni si giunga ad una definizione cronostratigrafica univoca del lgm. 149osservazioni sul significato ... 4. implicazioni in altri settori della geologia del quaternario 4.1. lgm nelle carote di ghiaccio a partire dagli anni ’90 la dizione lgm viene comunemente usata anche nelle pubblicazioni sulle carote di ghiaccio, per indicare il ristretto intervallo di tempo di massimo volume dei ghiacci/minimo livello del mare, evidenziato dalla stratigrafia isotopica marina, intervallo di tempo in cui si registrano condizioni generali di minimo termico nelle regioni polari. in realtà la documentazione fornita dalle carote di ghiaccio è assai articolata e i diversi indicatori climatici forniscono una storia climatica complessa, con differenze anche marcate tra i due emisferi e pure in ambito regionale. così, nelle carote prelevate in groenlandia, tra 25 e 19 ka cal bp vi è un ampio minimo δ18 o (peraltro interrotto da un picco intorno a 21 ka, interstadio 2, gi2, walker et al., 1999) mentre in precedenza dominano le fluttuazioni ad alta frequenza dei cicli d/o (dansgaard et al. 1993). in antartide, invece, come recentemente indicato con elevato dettaglio nella carota epica edc96, vi è un ampio e sostanzialmente piatto minimo δd (temperatura sul sito), tra circa 28 e 18 ka cal bp (fig. 1), mentre l’eccesso di deuterio, interpretato come indicatore della temperatura nell’area sorgente dell’umidità (l’oceano meridionale), mostra un ampio minimo a 16 20 ka cal bp (stenni et al., 2003). 4.2. lgm in geologia glaciale nello studio dei depositi glaciali continentali la dizione “last glacial maximum” (o altre affini) è stata usata inizialmente per indicare, in senso geografico, il limite più esterno raggiunto dai margini glaciali durante l’ultima massima avanzata, senza una diretta e sicura implicazione temporale. tale massima avanzata era genericamente attribuita al late wisconsin o equivalenti (si veda, ad es., schlüchter, 1982), ma già negli anni ’80 era chiaro che, da luogo a luogo, tale limite non era sincrono e poteva essere più antico o più recente del last glacial maximum (lgm), così come concepito dagli stratigrafi del quaternario marino. un panorama aggiornato di questa problematica si puo’ trovare in clark & mix (2002). percepita questa differenza, molti geologi del glaciale hanno introdotto l’uso del termine lgm con significato locale, per rimarcarne la differenza temporale rispetto al “global lgm” o comunque la sua indipendenza: sono così comparse nella letteratura dizioni come “local last glacial maximum”, “mountain glacier lgm” ”new zealand lgm”, ”local tibetan lgm”, ecc. (ad es. owen et al. 2002; smith et al, 2005). per altro la dizione lgm viene spesso anche usata (vedi florineth e schluchter, 2000) per indicare la fase di picco di avanzata glaciale (intorno a 18-20 ka 14c bp) sincrona del lgm, così come definito in termini di massimo volume globale di ghiaccio. da ultimo, nel lavoro di sintesi sulla storia della calotta eurasiatica (svendsen et al., 2004), lgm viene usato quasi come sinonimo di mis/ois 2 e di late weichselian, sebbene talora si precisi anche la sua durata temporale (20-15 ka). nel complesso, quindi, i geologi del glaciale usano piuttosto liberamente il termine lgm, ma 150 comunque riservandolo al late wisconsin/weichselian ed equivalenti, avendo accertato che localmente si sono prodotte espansioni glaciali più estese in tempi precedenti come, ad esempio, nel settore asiatico (ma non in quello scandinavo) della calotta euroasiatica (svendsen et al., 2004) o nelle alpi francesi (guiter et al., 2005). 5. relazioni tra lgm e la cronostratigrafia alpina per l’ultimo ciclo glaciale: il würm come si è visto, la comunità scientifica internazionale indica come last glacial maximum la fase di massimo volume glaciale globale (segnale isotopico) e di minimo livello del mare equivalente, raggiunti durante l’ultimo ciclo glaciale successivo all’eemiano, e più precisamente durante l’ultima maggiore espansione glaciale, comunemente indicata come late wisconsin (ed equivalenti), in parte coincidente con lo stadio isotopico 2. può essere qui utile puntualizzare lo stato della cronostratigrafia alpina allo scopo di definirne meglio le relazioni con il lgm. la risoluzione n. 6 della subcommission european quaternary stratigraphy (seqs) (chaline & jerz, 1984) attribuisce al würm il significato di piano cronostratigrafico di valore regionale, stabilisce un’area tipo (la regione di isar-loisach in baviera) e indica criteri (litoe palinostratigrafici) per la suddivisione in tre sottopiani (inferiore, medio, superiore) in alcune sezioni scelte. le prime fasi dell’ultima glaciazione, recentemente riconosciute sul versante settentrionale delle alpi, sono datate 105 ka bp (preusser, 2004). il würm superiore viene fatto iniziare – nella sezione (stratotipo) di baumkirken presso innsbruck al passaggio da un’unità di argille lacustri alle ghiaie e quindi ai till soprastanti, che rappresentano l’evidenza dell’ultima fig. 1 tavola stratigrafica relativa all'intervallo 60 10 ka cal bp che illustra alcuni dei dati discussi nel testo. sono stati impiegati i limiti degli stadi isotopici marini indicati da shackleton (2000) e la definizione e suddivisione del würm secondo la risoluzione dell’inqua-seqs (chaline & jerz, 1984). la stratigrafia isotopica grip è tratta da dansgaard et al. (1993); björk et al. (1998); walker et al. (1999). la curva delle variazioni del livello del mare è ripresa da lambeck et al. (2002). la curva δd della carota antartica epica edc96 (stenni et al., 2003) è commentata nel testo. l'interpretazione e l'estensione cronologica del termine tardoglaciale è quella proposta in questo lavoro (discussione nel testo). le fasce barrate indicano ambiti di incertezza dei rispettivi limiti. stratigraphic framework of the time interval between 60 and 10 ka cal bp; mis boundaries according to shackleton (2000). the definition and subdivision of the würm stage follow the inqua-seqs resolution (chaline & jerz, 1984). the grip isotopic stratigraphy is from dansgaard et al. (1993); björk et al. (1998); walker et al., (1999). the sea level curve is from lambeck et al. (2002). the δd curve from the antarctic core epica edc 96 (stenni et al., 2003) is commented in the text. the term lateglacial is used in the sense discussed in the present paper (see text). the crossed pattern shows the interval of time uncertainty of the relevant limits. g. orombelli, c. ravazzi & m.b. cita 151 espansione glaciale. per la sezione di baumkirken sono disponibili un diagramma pollinico e date 14c (fliri et al., 1970; bortenschlager & bortenschlager, 1978): il würm superiore (e l’equivalente geocronologico “würm recente”) inizia quindi intorno a 25 ka 14c bp (ca 29 ka cal bp). sempre la risoluzione n. 6 della seqs indica che il würm termina con l’inizio dell’olocene, con limite attualmente datato 11,5 ka cal bp (gradstein et al., 2004). la letteratura transalpina più recente ha sostanzialmente recepito queste indicazioni, sia pure con limiti temporali un poco diversi. così, ad esempio, campy & arn (1991), van husen (1997), florineth & schluchter (2000), buoncristiani & campy (2001), preusser et al. (2003) e preusser (2004) indicano come late würm l’intervallo 24 -11 ka 14c, circa corrispondente al mis 2. per tutti questi autori il würm superiore include le fasi di ritiro glaciale, complessivamente comprese nel lateglacial (tardoglaciale). su questa base, risulta chiaro che il termine cronostratigrafico würm superiore, così come definito nelle risoluzioni internazionali, ha valenza regionale e comprende interamente l’ultima maggiore espansione glaciale nelle alpi, inclusa la fase di avanzata e quella di deglaciazione, mentre il termine lgm ha valenza globale e riguarda un intervallo di tempo più ristretto. 6. tardoglaciale e postglaciale tardoglaciale (questa dizione è più corretta di "tardiglaciale", in analogia a molti altri termini simili, usati come aggettivi o sostantivi, quali: tardogotico, tardoromanico, tardoneolitico, tardopaleozoico, ecc.; in geologia le parti finali di una suddivisione geocronologica sono spesso indicate premettendo l'aggettivo "tardo", ad es. tardo miocene, tardo quaternario) è la traduzione di lateglacial/spätglazial ed è stata informalmente usata per indicare la fase di transizione climatica successiva al lgm, contrassegnata da riavanzate o stazionamenti, via via più arretrati, degli apparati glaciali, fino alla loro riduzione (nel caso dei ghiacciai montani) a dimensioni circa uguali a quelle attuali. in questo senso, sulle alpi, il tardoglaciale (anche indicato come tardowürm/tardowürmiano) è stato usato, a partire dagli anni ’60, come termine complessivo, per indicare gli stadi glaciali (stadiali) già individuati da penck e brückner (1909), e originariamente attribuiti al “postglaciale – post-würmiano” (si veda maisch, 1982). una vasta bibliografia si è accumulata su questo argomento, con l’introduzione di numerosi nuovi “stadi” con denominazioni locali, particolarmente in austria e in svizzera, ma anche in italia, generalmente non definiti cronologicamente e tra loro distinti e correlati con criteri paleoglaciologici (altitudine del limite delle nevi). van husen (1997) in austria riconosce, dopo il lgm, le fasi di ritiro bühl, steinach, gschnitz, daun, egesen. maisch (1982) in svizzera distingue gli stadi bühl, steinach, gschnitz, clavadel, daun, egesen (distinto in tre sottostadi, max., bockten, kromer), l’ultimo sottostadio potendo già appartenere all’olocene basale (preboreale, kelly et al., 2004). lo stadio bühl da taluni autori non è incluso nel tardoglaciale. tramite date 14c ottenute in successioni polliniche in area alpina è stata proposta una correlazione tra lo stadio gschnitz e il dryas inferiore (oldest dryas) e tentativamente datato intorno a 14 ka 14c bp (van husen, 1997). questa correlazione è tuttavia messa in dubbio da più recenti revisioni del quadro palinostratigrafico del tardoglaciale centro-europeo, che evidenziano come la biozona dryas inferiore (oldest dryas) sia stata impiegata, al di fuori della sua area tipo, in maniera difforme dal significato originario (litt et al., 2003). lo stadio di egesen è stato correlato con il dryas recente (younger dryas) sulla base di datazioni con nuclidi cosmogenici di massi sulle morene deposte dai ghiacciai di aletsch e vadret lagrev in svizzera. nel caso dell’aletsch, per le sue grandi dimensioni e la sua lenta risposta, le morene attribuite allo stadio multifase di egesen si sarebbero formate durante l’ultima sua fase di avanzata, probabilmente nell’olocene basale (kelly et al., 2004). il termine lateglacial (spätglazial) è già impiegato negli anni cinquanta nella letteratura palinologica centro-europea per indicare informalmente un complesso di condizioni climatiche, sedimentologiche e paleogeografiche che precedono l’espansione di foreste di latifoglie termofile con quercus e corylus al termine dell’ultima glaciazione (firbas, 1954; welten, 1979). il limite inferiore dello spätglazial, nel senso impiegato dalle scuole di firbas e di welten, non era ben definito in termini stratigrafici, per ragioni tecniche connesse con i limiti delle capacità di perforazione di quegli anni, che non consentivano di raggiungere i livelli più profondi dei bacini lacustri e di torbiera (welten, 1979), nonché per via dello scarso contenuto pollinico di questi depositi. nell’ultimo cinquantennio è stata dimostrata la correlabilità tra criteri palinologici, isotopici (ottenuti nelle carote di ghiaccio) e dendrocronologici per il limite superiore del lateglacial. questo limite è posto in maniera univoca in corrispondenza di un brusco evento isotopico, palinologico e dendrocronologico a 11.550 ± 50 anni cal bp (10.000 14c bp), che coincide con l’inizio dell’olocene (dansgaard et al., 1989; jonhsen et al., 1997; friedrich et al., 1999; merkt & muller, 1999; litt et al ., 2003) ed è accettato dalla international commission on stratigraphy (gibbard, 2004). per quanto riguarda la caratterizzazione della parte iniziale del lateglacial non vi è ancora accordo unanime nella letteratura. la maggior parte degli autori dell’europa centrooccidentale sono orientati ad assumere come limite pleniglacial/lateglacial il brusco miglioramento climatico che segna l’inizio del gi-1 (greenland interstadial 1) (circa corrispondente al “bølling-allerød”), posto a 14.700 anni cal bp nel record isotopico della carota grip e a circa 12.500 anni 14c nelle successioni lacustri dell’europa centro-occidentale (johnsen et al., 1997; lowe & walker, 1997; walker, 1999; walker et al., 1999; litt et al., 2003), riprendendo un uso precedente già impiegato in palinostratigrafia nelle medesime regioni (van der hammen et al., 1971). altri autori impiegano il termine con valenza globale e fanno iniziare il lateglacial al termine del lgm, quindi a circa 18 mila anni cal bp (orombelli & ravazzi, 1996; lambeck et al., 2000); altri ancora lo impiegano con valenza cronostratigrafica regionale, facendo coincidere la base del lateglacial con l’età presunta delle fasi iniziali della deglaciazione locale. seguendo l’uso cronostratigrafico regionale del termine connesso con l’inizio della deglaciazione locale, non sincrono nelle diverse regioni glacializzate, si hanno diverse età d’inizio del lateglacial, osservazioni sul significato ... 152 ad esempio circa 15.8-14.4 mila anni cal bp in scozia (birnie et al., 1993), o 17.5 mila anni cal bp in svizzera (preusser, 2004); inoltre, in questo senso il termine non potrebbe essere impiegato al di fuori delle aree glacializzate. gli scriventi ritengono che il termine lateglacial, come lgm, dovrebbe essere connotato da criteri stratigrafici a scala globale, volti alla valutazione delle trasformazioni che si sono svolte tra la culminazione dell’ultima fase fredda (lgm) e il brusco riscaldamento rilevato, sempre a scala globale, in corrispondenza dell’inizio dell’olocene. con questo significato, il lateglacial non corrisponde alla deglaciazione postlgm, anche se nelle alpi (ma non in nord-america) la include quasi per intero, salvo gli stadi iniziali da taluni considerati ancora pleniglaciali e salvo una possibile coda (fase kromer dello stadio egesen) nel preboreale. d’altra parte la cronologia dell’ultima deglaciazione nelle alpi è mal definita a causa della scarsità di materiale vegetale, prodotto da piante terrestri, databile con il radiocarbonio. se si fa iniziare l’ultima deglaciazione nel momento in cui i ghiacciai abbandonano definitivamente la posizione raggiunta negli anfiteatri (ove esistono) o nei fondovalle nel würm superiore, allora l’età di 17.5 ka cal bp indicata da niessen & kelts (1989) per la deglaciazione del lago di lugano, e ripresa da preusser (2004), è da considerarsi posteriore all’inizio della deglaciazione. per il versante meridionale delle alpi, le date più antiche e affidabili, in quanto ottenute su legno, e certamente posteriori all’inizio della deglaciazione, sono quelle dei larici di revine, vittorio veneto. per questa località sono riportate età molto vicine a quelle corrispondenti alla fine del lgm (15,2 ka 14c bp secondo friedrich et al., 1999, ovvero 18,6 ka cal bp, calibrazione secondo calib 5.0). nella medesima area di revine, il ghiacciaio si trovava in posizione di massima avanzata poco dopo 17,7 ka 14c bp (pari a circa 21,0 ka cal bp). questa è infatti l’età di legni inclusi nel till della cerchia più esterna dell’anfiteatro di vittorio veneto (bondesan, 1999). tenendo conto di questi dati, ravazzi (2003) adotta un’età di ca 15,5 ka 14c bp (ca 18.9 ka cal bp) per l’inizio della deglaciazione a sud delle alpi. il termine postglacial (post-glacial, postglaciale) è impiegato da un secolo nella letteratura internazionale per indicare l’intervallo di tempo che segue il termine dell’ultimo ciclo di avanzata e ritiro glaciale del pleistocene (webster's revised unabridged dictionary, 1913). il postglacial segue il lateglacial e come tale è generalmente considerato un sinonimo di olocene, anche se privo della connotazione cronostratigrafica di quest’ultimo (roberts, 1989; lowe & walker, 1997). e’ un termine informale, ormai poco utilizzato, preferibilmente da abbandonarsi. 7. proposte le osservazioni qui presentate, circa l’uso dei termini lgm e tardoglaciale in stratigrafia, ne sottolineano la valenza globale, che è andata progressivamente precisandosi a partire dagli anni ’70 con lo sviluppo della stratigrafia dei sedimenti oceanici e dei ghiacci polari. l’analisi svolta nella presente nota ha evidenziato che questi termini hanno preso origine da concetti relativi ad eventi geologici globali registrati nei sedimenti e sono quindi oggetto della stratigrafia ad eventi, di cui anche la climatostratigrafia è parte integrante. per ragioni pratiche, soprattutto nelle aree in cui il record geologico non contiene i proxy data che consentono l’individuazione diretta di tali eventi, è stata proposta anche una definizione cronologica degli eventi, in particolare per i limiti inferiore e superiore del lgm e per il brusco passaggio tra il tardoglaciale e l’olocene. tale impiego dei termini in senso cronostratigrafico può servire anche agli scopi della cartografia geologica regionale, nell’individuazione delle relazioni tra le età dei corpi cartografati e gli eventi globali che controllano e indirizzano la loro formazione. per queste finalità è auspicabile anche lo sviluppo di una cronostratigrafia di riferimento regionale, che tenga in considerazione l’espressione locale diacronica degli eventi e sottolinei i processi di volta in volta attivi nelle diverse aree. la sottocommissione per il quaternario europeo (seqs) dell’inqua da oltre trent’anni si occupa di contribuire allo sviluppo di scale cronostratigrafiche di valore regionale nelle diverse parti d’europa. per quanto riguarda le alpi, vent’anni fa la seqs ha formulato uno schema di riferimento per il pleistocene superiore (chaline & jerz, 1984), tuttora largamente usato da gran parte dei quaternaristi alpini, come evidenziato anche nella presente nota. in particolare, riteniamo che il significato cronostratigrafico attribuito al würm superiore sia stato correttamente precisato dall’istituzione di una sezione tipo, con significato regionale di riferimento per l’inizio dell’ultima espansione glaciale nelle alpi. l’impiego di una sezione tipo in ambito continentale è formalmente corretto, secondo il codice di nomenclatura stratigrafica (salvador, 1994) ed è di particolare utilità nella cartografia geologica. l’intervallo rappresentato dai depositi del würm superiore abbraccia infatti per intero l’ultimo evento di espansione glaciale durante l’ultimo ciclo glaciale-interglaciale (pleistocene superiore), includendo le fasi di avanzata, di massima espansione e di ritiro. ci si augura pertanto che i rilevatori dediti al rilevamento delle unità quaternarie prendano atto dell’esistenza di questi strumenti, utili a fornire un quadro interpretativo a scala extralocale dei processi geologici, che pur trovano espressioni diverse nelle diverse aree geografiche. in questa prospettiva è giocoforza accrescere il patrimonio disponibile di datazioni relative e numeriche – che sul versante italiano delle alpi appare ancora inadeguato a comporre un quadro unitario dello svolgersi dei processi geologici e climatici. per quanto riguarda l’impiego del termine lgm, le affermazioni contenute nel paragrafo 1 dell’articolo di bini et al. (2004) non sono, a parere degli scriventi, accettabili alla luce delle argomentazioni esposte nelle presente nota, come di seguito puntualizzato: 1 lgm ha significato globale, è uno “stato” o “condizione” della terra, quale quello prodottosi l’ultima volta, quando il volume complessivo dei ghiacci continentali ha raggiunto il valore massimo durante l’ultimo ciclo glaciale/interglaciale, intorno a 20.000 anni bp. ha quindi anche una valenza cronologica (pure se ancora da definirsi con precisione). pertanto lgm non ha dirette relazioni con le testimonianze di massima estensione areale, raggiunta g. orombelli, c. ravazzi & m.b. cita localmente dai ghiacciai, come discusso nel capitolo 3 della presente nota. la dizione “lgm locale”, talora usata in studi regionali, vorrebbe indicare l’espressione locale del lgm, in termini di locale massima estensione areale. riteniamo possa essere usata solamente per alludere alla estensione e configurazione dei ghiacciai possedute in una regione durante il lgm, quindi sostanzialmente nell’intervallo di tempo definito da questo termine. 2 lgm per definizione è “massimo”, quindi esclude le fasi di sviluppo ed aumento di volume globale e quelle di decadenza e diminuzione. si tratta di definire la durata e i limiti cronologici del massimo globale. 3 lgm per definizione è “ultimo” e fa pertanto riferimento unicamente all’ultima maggiore espansione glaciale durante l’ultimo ciclo glaciale/interglaciale. nelle alpi è pertanto da inquadrarsi nel würm superiore (late würm), come discusso nel capitolo 5 della presente nota. 4 lgm è un evento sincrono nel senso che è la fase in cui sulla terra il “livello del mare equivalente al volume dei ghiacci” (ice-volume-equivalent sea-level, lambeck & chappell, 2001), cioè la variazione di livello degli oceani depurata degli effetti locali dovuti alla tettonica, ed alla glacioed idro-isostasia, si è mantenuta sui valori negativi più accentuati (-140 m circa). la dizione pre last glacial maximum (pre-lgm), ove la si voglia usare, deve essere in accordo con il significato di lgm come sopra discusso, e comunque sembra agli scriventi una dizione informale, eccessivamente vaga e priva di contenuto. seguendo il significato attribuito da bini et al. (2004) al termine lgm, gli scriventi propongono di utilizzare in sua vece il termine cronostratigrafico würm superiore. pre-lgm a sua volta potrebbe essere sostituito da pre-würm superiore. il tardoglaciale merita un approfondimento, quanto al suo inizio: in particolare occorre chiarire se succede direttamente al lgm o se è da questo separato. qualora questo termine venisse utilizzato, andrebbe precisato con quale significato viene impiegato. se, nello spirito con cui è stata proposta nella nota di bini et al.(2004), la dizione lgm viene sostituita da würm superiore, tutto è risolto, poiché questo include il tardoglaciale. come sottodistinzioni possono essere indicate unità localmente distinte, sulla base di datazioni o di considerazioni sulla posizione nettamente interna ai depositi del würm superiore più esterni. postglaciale è un termine impreciso e non più usato dal punto di vista cronostratigrafico, anche a scala locale. con la p minuscola (quindi anche unità postglaciale upg) è una dizione informale che potrebbe sussistere, poiché risponde, provvisoriamente, all’esigenza di trovare un termine purchessia per indicare un complesso di depositi, che altrimenti riempirebbero di una pletora di nuovi nomi le carte. e’ chiaro che, in ambiente alpino, con questo termine verrebbero accorpati depositi del pleistocene terminale e depositi olocenici. questo accorgimento non dovrebbe, tuttavia, invitare alla pigrizia ed a trascurare un analisi, anche cronologica, più dettagliata di questo complesso di sedimenti, potenziale serbatoio di informazioni geologiche importanti per la comprensione dell’ ambiente attuale e delle sue dinamiche. bibliografia bini a., borsato a., carraro f., carton a., corbari d., cucato m., monegato g. & pellegrini g.b. 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(2000) timing of the last glacial maximum from observed sea-level minima. nature, 406, 713-716. 155 ms. ricevuto il 17 maggio 2005 testo definitivo ricevuto il 17 maggio 2005 ms. received: may 17, 2005 final text received: may 17, 2005 osservazioni sul significato ... microsoft word 11_furlani + revisori_lm05.doc available online http:/amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 25 (2), 2012, vii-ix the geoswim project: snorkel-surveying along 250 kilometres of the southern and western istrian coast stefano furlani department of mathematics and geosciences, university of trieste, italy corresponding author: s. furlani <sfurlani@units.it> the northeastern adriatic coast is dominated by high limestone plunging cliffs or slopes at wide-ranging angles. several authors (fouache et al., 2000, antonioli et al., 2004, 2007; furlani et al., 2011a) reported the occurrence of a well-carved submerged tidal notch at about -0.5/-0.7 m m.s.l. in the central part of the istrian peninsula, in correspondence of the limski kanal. moreover, furlani et al. (2011b) studied the coastal features of the northwestern sector, in particular the genesis and development of shore grykes. anyway, observation carried out along these rocky coasts, but also in general along all the rocky coasts of the world, are punctual and relative to short coastal sectors. as a consequence, it prevents the possibility to provide a global view of the surveyed coastal area. the geoswim project, of the department of mathematics and geosciences of the university of trieste, allowed to survey the morphological features of the whole southern and western istrian coast (fig. 1), like notches, sea caves, coastal assemblages of pinnacles, potholes, etc., and to collect physical parameters during the surveying. the northwestern istrian coast is dominated by limestones spanning in time spanning in time from the late jurassic to the eocene (velić et al., 2002, ). nearly horizontal or slightly inclined limestone bedding planes outcrop all over the western istria. limestone beds thickness is higher in correspondence of the limski kanal, in the central and most ancient part of istria (vlahović et al., 2005). n departur arrival km 1 sisan liznijan 6 2 liznijan kamp medulin 11 3 kamp medulin pomer 8 4 pomer kamp stupice 8 5 kamp stupice premantura 14 6 premantura banjole 11 7 banjole stoja 12 8 stoja pula 9 9 pula peroj 8 10 peroj bale 13 11 bale rovinj south 8 12 rovinj south rovinj north 10 13 rovinj north valalta 7 14 koversada zelena laguna 11 15 zelena laguna porec 7 16 porec cervar 13 17 cervar mirna 9 18 mirna novigrad 6 19 novigrad daila 8 20 daila sv. pelegrin 7 21 sv. pelegrin umag 8 22 umag savudrija 9 23 savudrija kanegra 7 24 kanegra strunijan 8 25 strunijan koper 12 26 koper san bartolomeo 6 26 san bartolomeo trieste 12 total lenght 250,17 fig. 1 left side: the study area. red and green lines are the laps. right side: the route and the length of the laps. furlani s. viii from a geomorphological point of view, the study area can be classified as a dalmatian coast (holmes, 1965). high plunging cliffs dominate the southwestern and the central part of the western istria, while the northern and southern coast is interested by limestone coastal slopes plunging at wide-ranging angles. the surveying was carried out along 260 km of coast during july 2012 using mask and fins. it can be considered a snorkeling surveying. the route was covered in 27 days (tab. 1), from šišan, in croatia, to trieste, in italy. two cameras, located on a 1.2 m boat specifically adapted for the project (fig. 2a, b), a canon g12 set in an underwater housing and the latter a 3d gopro camera, allowed to collect an ongoing video of large part of the istrian coast, both above and below sea level. moreover, a ctd-diver produced by eijkelkamp was pull in order to collect temperature and conducibility data along the coast. data collected, together with the video acquisition, allowed to accurately map the submerged notch and other coastal features, such as sea caves (fig. 3), potholes, etc, along the whole surveyed coast. data show that the submerged notch is confined to the central part of the istrian peninsula (fig. 4), the area where it was previously pointed out. the preliminary processing of physical data, even if they was strongly affected by the total lacking of rains during the surveying period, seem to indicate the occurrence of few large submarine springs in the same area of the occurrence of the submerged notch. future processing of recorded data and their mutual comparison will allow to precisely define the occurrence of limestone coastal features and their relations to coastal topography and physical seawater parameters. acknowledgements my acknowledgements go to many people who acfig. 2 a) preparation of the boat used during the surveying in southern istria (photo e. zavagno); b) surveying of coastal features and physical parameters of the sea near poreč (croatia). fig. 4 submerged tidal notch along the northeastern adriatic coast. the picture is made as a stereoscopic 3d as the results using filters of different colors, in this case red and cyan. red and cyan glasses are recommended to correctly view this image. fig. 3 a sea cave at premantura (croatia), in the southern sector of the istrian peninsula. the geoswim project: snorkel-surveying along istrian coast   ix tively participated at different stages of the scientific project, in particular prof. franco cucchi of the department of mathematics and geosciences of the university of trieste for the ongoing support, rados furlani for the assistance in the assemblage of the boat, sara biolchi, livio dorigo, giulio guglielmi, gaia cusatelli, federico furlani, roberto odorico, luca terribili, martina zaccariotto and enrico zavagno for the assistance during the swim-survey operations and many others. many thanks to the “riserva marina di miramare”, the “circolo istria” and the “istituto nautico di trieste” for the assistance before and after the survey. references antonioli f., carulli g.b., furlani s., auriemma r., marocco r. (2004) the enigma of submerged marine notches in northern adriatic sea. quaternaria, 8, 27-36. antonioli f., anzidei m., lambeck k., auriemma r., gaddi d., furlani s., orrù p., solinas e., gaspari a., karinja s., kovacic´ v., surace l. (2007) sea level change during holocene from sardinia and northeastern adriatic (central mediterranean sea) from archaeological and geomorphological data. quaternary science reviews, 26, 2463-24. faivre s., fouache e., ghilardi m., antonioli f., furlani s., kovačić v. (2011) relative sea level change in istria (croatia) during the last 5 ka. quaternary international, 232, 132-143. fouache e., faivre s., dufaure j-j., kovačić v., tassaux f. (2000) new observations on the evolution of the croatian shoreline between poreč and zadar over the past 2000 years. zeitschrift für geomorphologie suppl.-bd. 122, 33-46. furlani s., chersicla d., bressan g., biolchi s., cucchi f. (2011) shore grykes along the western istrian coast. acta carsologica, 40/1, 29-42. furlani s., cucchi f., biolchi s. & odorico r. (2011b) notches in the northern adriatic sea: genesis and development. quaternary international, 232, 158-168. furlani s., cucchi f., biolchi s. (in press) late holocene widening of karst voids by marine processes in partially submerged coastal caves (northeastern adriatic). geografia fisica e dinamica quaternaria. in press. holmes a. (1965) principles of physical geology. new york, ronald press. velić, i., vlahović, j., matičec, d. (2002) depositional sequences and palaeogeography of the adriatic carbonate platform. società geologica italiana, memorie, 57, 141-151. vlahović, i., tisljar, j., velić, i., matičec, d. (2005) evolution of the adriatic carbonate platform: paleogeography, main events and depositional dynamics. palaeogeography, palaeoclimatology, palaeoecology, 220, 333-360. ms. received: september 29, 2012 final text received: october 1, 2012 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /all /binding /left /calgrayprofile (gray gamma 2.2) /calrgbprofile (srgb iec61966-2.1) /calcmykprofile (u.s. web coated \050swop\051 v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.4 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings true /endpage -1 /imagememory 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<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> /ita (utilizzare queste impostazioni per creare documenti adobe pdf adatti per visualizzare e stampare documenti aziendali in modo affidabile. i documenti pdf creati possono essere aperti con acrobat e adobe reader 5.0 e versioni successive.) /enu (use these settings to create adobe pdf documents suitable for reliable viewing and printing of business documents. created pdf documents can be opened with acrobat and adobe reader 5.0 and later.) >> >> setdistillerparams << /hwresolution [1200 1200] /pagesize [396.850 566.929] >> setpagedevice impaginato castaldini aa mmeetthhooddoollooggyy ffoorr mmeeddiiuumm--ssccaallee sseeiissmmiicc ssuusscceeppttiibbiilliittyy mmaappss:: aann eexxaammppllee ffrroomm tthhee mmooddeennaa aappeennnniinneess ((nnoorrtthheerrnn iittaallyy)) ddoorriiaannoo ccaassttaallddiinnii11,, mmaassssiimmoo bbaarrbbiieerrii11,, ggiiuusseeppppee bbeetttteellllii11,, mmaarrccoo ccaappiittaannii11 && mmaarriioo ppaanniizzzzaa11 1dipartimento di scienze della terra, università degli studi di modena e reggio emilia abstract this paper describes a methodology for the implementation of medium-scale (1:50,000 scale) seismic susceptibility maps for assessing seismic hazard in territorial planning. it illustrates the research carried out in the modena and reggio emilia provinces with an example in the modena mid-apennines (area between zocca and rocca malatina). the research, supported by bibliographical investigations on quaternary active faults and on earthquake-induced surface effects, was organised according to the following studies: 1) study of the geological characteristics. elaboration of “geological maps”. 2) study of the litho-technical characteristics for the identification of the areas which may show homogeneous litho-technical behaviour in the occurrence of earthquakes. elaboration of “litho-technical maps” and of “simplified litho-technical maps” 3) study of geomorphological characteristics for the determination of geomorphological situations which may give local responses by causing relative amplification of seismic waves and/or earthquake-induced instability. elaboration of “geomorphological maps” and of “simplified geomorphological maps”; 4) study of seismic susceptibility characteristics for the identification of the areas prone to seismic amplification and/or earthquake-induced instability on the basis of previous data. elaboration of “maps of seismic susceptibility”. in these maps, the litho-technical features potentially causing amplification are shown with zones classified from 1 to 5 according to the increase of amplification (amplification from low to high); the morphological features causing amplifications (scarps higher than 20 m, narrow and long ridges) are shown with linear symbols. the features causing earthquake-induced instability are shown with zones indicated with letters from a to d according to the following classes of instability: a) stable areas and intermediate stability areas; b) potentially unstable areas with possible problems regarding the bearing capacity of soils; c) potentially unstable areas prone to mass movements; d) unstable areas prone to mass movements. the quaternary faults are also shown in the map. therefore, in the maps of seismic susceptibility the classes of susceptibility can be shown as zones with an alphanumeric code defined through the combination of numbers, from 1 to 5, and letters, from a to d (or with different areal symbols or different corresponding colours). the collected information was stored by means of geographic information systems (gis). the procedures for the implementation of the “maps of seismic susceptibility” were obtained by means of gis operations starting from the geological map, geomorphological map and the data base of the inventories of quaternary active faults and earthquake-induced surface effects. these maps give a sufficiently detailed picture of seismic hazard and susceptibility in the study area and can be easily consulted and understood by technicians from administration boards. the research herein described is qualitative and not quantitative and therefore, considering also the scale adopted, it can be considered as a grade 1 zonation (cf. tc4, 1999). riassunto una metodologia per la realizzazione di carte della pericolosità sismica a scala media: un esempio dall’appenino modenese (italia settentrionale). questa nota descrive una metodologia per l’elaborazione di carte, a media scala (1:50.000), per la valutazione della pericolosità sismica nell’ambito della pianificazione territoriale. essa illustra le ricerche eseguite nelle province di modena e reggio emilia con un esempio nel settore del medio appennino modenese (area tra zocca e rocca malatina). la ricerca, supportata da indagini bibliografiche sulle faglie quaternarie e sugli effetti superficiali sismoindotti, si è svolta secondo i seguenti studi: 1) studio delle caratteristiche geologiche. elaborazione di “carte geologiche”; 2) studio delle caratteristiche litotecniche per l’identificazione delle aree a comportamento litotecnico omogeneo in occasione di eventi sismici. elaborazione di “carte litotecniche” e “carte litotecniche semplificate”; 3) studio delle caratteristiche geomorfologiche per l'individuazione delle situazioni geomorfologiche che possono dare locali risposte causando amplificazione relativa delle onde sismiche e/o fenomeni di instabilità da terremoto. elaborazione di “carte geomorfologiche” e “carte geomorfologiche semplificate”. 4) studio delle caratteristiche di suscettibilità sismica per l’identificazione delle aree predisposte all’amplificazione sismica e/o a fenomeni di instabilità da terremoto sulla base dei dati precedentemente elaborati. elaborazione di “carte della suscettibilità sismica”. in queste carte, le aree predisposte all’amplificazione sismica sono classificate da 1 a 5 secondo un ordine crescente dell'amplificazione (da bassa ad alta); gli elementi morfologici che possono causare amplificazione (scarpate maggiori di 20 m, dorsali strette ed allungate) sono indicati con simboli lineari. le zone potenzialmente esposte a fenomeni di instabilità da terremoto sono indicate secondo le seguenti classi di instabilità: a) aree stabili o a stabilità intermedia; b) aree potenzialmente instabili con possibili problemi riguardanti la capacità portante del terreno; c) aree potenzialmente instabili esposte a movimenti di massa; d) aree instabili esposte a movimenti di massa. nelle carte vengono anche indicate le faglie quaternarie. pertanto nelle “carte della suscettibilità sismica” le classi di suscettibilità possono essere indicate con un codice alfa-numerico derivato dalla combinazione di numeri, da 1 a 5, e di lettere, da a a d, (o con diversi simboli areali oppure con diversi colori ad esse corrispondenti). i dati raccolti sono stati inseriti in una banca dati gis. l’elaborazione delle “carte della suscettibilità sismica” è stata realizzata attraverso operazioni gis partendo dalle carte geologiche, dalle carte geomorfologiche e dai data base delle faglie quaternarie e degli effetti superficiali sismoindotti. tali carte offrono un quadro sufficientemente dettagliato della pericolosità sismica e della suscettibilità dell’area di studio e sono facilmente consultabili e comprensibili da parte dei tecnici delle amministrazioni pubbliche. le ricerche descritte sono di tipo qualitativo e non quantitativo, pertanto, anche in considerazione della scala adottata, possono essere considerate come studi di zonazione di grado 1 (cfr. tc4, 1999). key words: geology, geomorphology, seismic hazard, seismic susceptibility, modena and reggio emilia provinces, northern italy. parole chiave: geologia, geomorfologia, pericolosità sismica, suscettibilità sismica, province di modena e reggio emilia, italia settentrionale. il quaternario italian journal of quaternary sciences 1155(2), 2002, 229-249 230 d. castaldini et al. 11.. iinnttrroodduuccttiioonn it is common knowledge that a correct methodological approach for the study of seismic hazard in a certain area should first provide for regional-scale investigations and, subsequently, local, specific studies. the product of investigations at a regional scale consists of a series of maps capable to describe the general seismic hazard of the area investigated. afterwards detailed investigations at a 1:10,000 scale (microzonation) or larger should be carried out in the areas subject to urban planning. in 1999 the administrations of the provinces of modena and reggio emilia stipulated a convention with the local university aiming at defining, in a period of two years, the knowledge concerning the assessment of seismic hazard and seismic susceptibility in their territory, since sufficiently detailed studies on this important topic were not available. this research was carried out considering that the institutional aims of the provincial administration boards in the field of territorial planning are between the national-regional level (the levels of law promulgation) and the municipal level (the level of local application of national and regional laws and the directions from the provinces). therefore the provinces are called to give to the municipalities useful directions for local territorial planning, but they cannot produce a real seismic microzonation because of either the vastness of their territories and the fact that the real authority for local territorial planning is given to the municipalities. therefore, the aim of the research was the acquisition of a sufficiently detailed picture of seismic hazard and seismic susceptibility in the provinces of modena and reggio emilia in order to identify the areas which could show problems due to seismic amplification and/or stability in dynamic conditions. these areas will be of particular concern for the administration boards at a municipal level and detailed investigations will be properly directed for assessing seismic hazard in territorial planning (seismic microzonation). this paper, after a regional outline on geologicalstructural, neotectonic, and seismotectonic characteristics and on earthquake-induced surface effects, describes the geological and geomorphological studies carried out for the implementation of medium-scale (1:50,000) seismic susceptibility maps in the modena and reggio emilia provinces and, in particular, it illustrates an example of these studies in the modena mid-apennines (area between zocca and rocca malatina). with the term seismic susceptibility the seismic hazard induced by the physico-geographical situations is meant (such as lithological, geomorphological situations, etc. of the area considered) (cf. panizza 1991 and 1996). in other words, the “seismic susceptibility maps” illustrated here are maps of the areas prone to seismic amplification and/or earthquake-induced instability. the modena and reggio emilia provinces are located in northern italy in the emilia-romagna region (fig. 1), the total extension of their territory being about 5,000 km2. the southern sector of their territory belongs fig. 1 geological sketch of the northern apennines (after gasperi et al., 1986) and location of the modena and reggio emilia provinces and the example area (zocca rocca malatina area) (thick lines). inquadramento geologico dell’appennino settentrionale (da gasperi et al., 1986) e ubicazione delle province di modena e reggio emilia e dell’area di zocca rocca malatina (linee in grassetto). to the northern apennines whereas the northern sector belongs to the po plain. the example area is located in the mid-apennines of the modena province between the hamlets of zocca and rocca malatina. this area was chosen because of its geological and geomorphological characteristics which are very common in the modena and reggio emilia mid-apennines. moreover, since 1994 this territory has been the epicentral area of several earthquakes (magnitude 1.5 to 2.5) recorded by the local seismic network (zucchi, 1995, 1996, 1997, 2000 and 2001) and it is close to the epicentral areas of the two strongest earthquakes which affected the modena and reggio emilia apennines in the past years. the first earthquake occurred in the night of december 31st 1995, with a 3.3 magnitude and intensity v of the mercalli-cancani-sieberg (mcs) scale; the second quake occurred on 7th july 1999 with a 4.6 magnitude and intensity vi mcs. 22.. aa sshhoorrtt rreevviieeww ooff ssttuuddyy mmeetthhooddoolloo-ggiieess ffoorr sseeiissmmiicc ssuusscceeppttiibbiilliittyy iinn iittaallyy in recent years the italian “national group for the defence against earthquakes” (gndt) has carried out a project for assessing seismic hazard in italy to be used as a basis for the revision of the seismic zonation at a national level. the final results of this project, which have regarded both the geological and seismological aspects, have been described by slejko et al. (1998) and galadini et al. (2000). in particular, galadini et al. (2000) collected the scientific articles relative to the investigations carried out by the gndt on the topic of seismic hazard in the 1996-99 period. however, since the main goal of this paper is the illustration of a methodology for the implementation of seismic susceptibility maps for territorial planning, it is opportune to review the methodologies concerning this field which have been proposed in italy in the last 20 years that is after the destructive earthquake (main shock 6.8 magnitude and intensity x mcs scale) which occurred on november 23rd, 1980 and struck a vast area in southern italy. nevertheless, considering the vast literature on this topic, it does not claim to be exhaustive. basically, there are two approaches finalised to the implementation of seismic hazard maps. the first is the “qualitative” approach by which the zones prone to amplification and/or instability in dynamic conditions are mapped. the best advantages of this approach consists in the possibility of application to large areas and a rapid zonation, although the accuracy is not high. the “quantitative” approach focuses on the seismic behaviour of a small area and makes use of data from field and laboratory tests which are generally used for calculating the “factors of safety”. the advantage of this approach is the high accuracy obtained, whereas the disadvantage consists in the long times required for zonation in rather large areas. some methods are based on the combination of the two approaches, by making use of the quantitative approach for the analysis in sample sites and, subsequently, extending the data to wider areas. siro & bigi (1983) illustrated the seismic microzonation investigations carried out in 39 inhabited centres of campania and basilicata struck by the november 231a methodology for medium scale ... 23rd, 1980 earthquake. these investigations were directed towards the implementation of geological-technical maps, seismic microzonation maps and maps of areal distribution of damage. methods for mapping geological and geomorphological elements associated with earthquake hazard conditions have been proposed by blumetti et al. (1987), bisci et al. (1990) and bisci & dramis (1992) for the marche region. the cartographic elements shown in these papers are particularly directed to territorial planning and can be adopted at different scales (from small to large scales) according to their purpose. in garfagnana (tuscany), d’amato avanzi et al. (1993) used a method which requires detailed geological and geomorphological surveys in order to draw up a map on which active and dormant landslides can be shown as well as areas potentially exposed to mass movements in case of earthquake because of their morphological and lithological features. a part from qualitative works, several quantitative studies have been carried out (e.g., among the most recent: pergalani, 1996; crespellani et al. 1996 and 1998; frassineti et al., 1997; pergalani et al., 1998, 1999, 2000 and 2002; luzi et al., 2000; regione toscana, 2000; marcellini & maugeri, 2001a and 2001b). in particular, in pergalani et al. (1998), the investigations aimed at the elaboration of instability maps, in static and dynamic conditions, in the apennine sector of lombardy. the main result of this study — carried out through the collection of geological-geomorphological data, gis-data elaboration, univaried and multivaried analysis on point data, identification of the hazardous areas by means of statistical methods, sensitivity analysis — are several maps (at a 1:10,000 scale) which can be a reliable tool in the field of territorial planning. the susceptibility of slopes to failure during earthquakes was calculated in terms of critical horizontal acceleration, on a subregional scale for a sector of the tuscan apennines by luzi et al. (2000). according to the working scale (1:10,000) and the availability and accuracy of the input data, the infinite slope analysis resulted in being the most appropriate method. a geological, geomorphological and hydrogeological study of the area was carried out and the geotechnical parameters were collected from local administrations. all the data were stored in a gis, used as a tool to build the spatial and attribute data base and prepare the input data layers for stability analyses. the final results can be useful to land use planners or can be used to give priorities to engineering projects. pergalani et al. (2000) published a volume devoted to the fast seismic microzonation of 782 inhabited centres struck by the 1997-1998 seismic sequence which occurred in the umbria and marche regions. in this paper, the local geological, geomorphological, hydrogeological and seismostratigraphic conditions capable of causing amplification of the seismic input, with respect to geological reference conditions (bedrock), and/or permanent displacements (landslides, liquefaction, settlements and strains) have been considered. the maps elaborated at the 1:5,000 scale (geological-structural map, geomorphological map, lithotechnical map, map of the areas susceptible of local dynamic amplification or instability) were therefore correlated with previously analysed sample situations by means of 232 models in which a seismic movement resulting from historical and statistical analyses of regional seismic hazard was imposed. also marcellini & maugeri (2001a and 2001b) published special issues devoted to the study of some areas struck by the 1997-1998 umbria-marche seismic sequence. the issues illustrate microzonation methods both in the light of scientific aspects and criteria of practical application. these methods have geological maps, geomorphological maps and lithotechnical characterisation of the bedrock units as basic documents. qualitative-quantitative studies have been carried out in small areas of the tuscan-emilia apennines by castaldini et al. (1997, 1998a, 1998b). the method of these researches was based on multidisciplinary studies in order to better emphasise the complexity of the relationships between all the parameters affecting slope stability in static and dynamic conditions. a significant aspect of these studies was the attempt to improve the exclusively descriptive aspects of research on the relationship between earthquakes and induced surface effects, and to introduce a methodological approach by which this interaction can be quantified. one of the limits to the method proposed is that some factors were not utilised in the numerical definition of the stability conditions: the introduction of these factors might in fact modify the zonation of the maps of relative proneness to instability in non-seismic and seismic conditions. in the framework of the studies on seismic hazard mapping for administrative purposes, worthy of note is the work by peruzza et al. (2001) which describes an ongoing project, in the friuli-venezia giulia region in ne italy, in which, in the first phase of this project the soil conditions were considered, for defining attenuation d. castaldini et al. fig. 2 map of the seismogenetic zones of italy (after meletti et al., 2000) the grey area corresponds to the modena and reggio emilia provinces. carta delle zone sismogenetiche d’italia (da meletti et al., 2000). l’area in grigio indica le province di modena e reggio emilia. 233 relationships, on the basis of the lithological characteristics (prevailing rock type class). the local soil conditions, roughly summarized by considering a reference soil for each municipality of the region, are introduced into probabilistic seismic hazard estimates; the subsequent improvement is checked by comparing these new results and the maximum observed intensities in each municipality to investigate if the major differences between probabilistic estimates and actually observed data can be explained by local site effects and/or by the geometry of the seismogenetic zones used in the computation. from the review carried out, although short, it results that the methodologies aiming at the elaboration a methodology for medium scale ... fig. 3 schematic map of quaternary active faults in the modena and reggio emilia provinces. carta schematica delle faglie quaternarie delle province di modena e reggio emilia. 234 of cartographic documents (at various scales) on the seismic hazard of a certain territory have to take in account soil conditions and, therefore, have as basic documents, geological, geomorphological and lithotecnical maps. 33.. ggeenneerraall oouuttlliinnee ooff tthhee mmooddeennaa aanndd rreeggggiioo eemmiilliiaa pprroovviinncceess 33..11.. ggeeoollooggiiccaall--ssttrruuccttuurraall cchhaarraacctteerriissttiiccss a general geological sketch of the reggio emilia and modena provinces is shown in fig. 1. from a geological standpoint, the whole study area belongs to the northern apennines that are a fold-and-thrust belt built up mainly during the tertiary. during this period the convergence between the european and the adriatic plates caused, at first, the consumption of the interposed tethyan oceanic crust and, then, the collision between the two plates which led to the formation of this mountain chain. the main units forming the reggio emilia and modena apennines belt are: i) tuscan units, made up of tertiary flysches, continuously outcropping along the chain’s axis; ii) ligurian units made up of deep sea sediments including jurassic ophiolites followed by thick sequences of cretaceous to eocene calcareous or terrigenous turbidites; iii) the mainly terrigenous epiligurian sequences of the middle eocene to late messinian unconformably overlying the previously deformed ligurian units; iv) the plio-quaternary marine terrigenous deposits unconformably overlying the ligurian units and the epi-ligurian sequence and dipping under the alluvial deposits of the po plain (pieri & groppi, 1981). from the structural viewpoint the study area can be subdivided into three parts, from south to north (bettelli et al., 1994; 1996a; 1996b). the structural setting of the southern sector (high mountain sector) is characterised by important extensional fault systems generally nw-se trending. the central sector (midmountainous and hilly areas) shows a more complex structural style, given by a network of faults generally nw-se and ne-sw trending (strike-slip and normal faults were recognised southward, while compressive structures seem to prevail northward). in the northern sector (po plain) compressive geological structures (thrust systems), buried under the quaternary continental sediments of the po plain were recognised: the emilia folds and the ferrara folds. 33..22 nneeootteeccttoonniicc cchhaarraacctteerriissttiiccss the neotectonics characteristics of the study area are represented in bartolini et al. (1982) and cnr (1983). within the framework of this research, an inventory of quaternary active faults was set up with the compilation of a “map of quaternary active faults” and of fault data sheets. the “map of quaternary active faults” (fig. 3) contains the various faults which have been numbered, classified as “active” or “held to be active” (according to the definitions by panizza & castaldini, 1987) and subdivided into “outcropping” or “buried”. the data sheets for each fault, or group of faults, contain information on their characteristics (see castaldini et al., 2000). on the whole, in the modena and reggio emilia provinces 40 faults, or fault systems, were inventoried and mapped; 15 were classified as “active” and 25 as “held to be active”. the main elements are nw-se and wnw-ese oriented, according to the apennine chain trend, whereas the other prevalent trend is sw-ne and ssw-nne. in the mountain area faults “held to be active” show only geomorphological evidence of tectonic activity. the “active” faults are located along the apennine margin; in this area, many faults and folds affect the marine quaternary sediments. in the po plain sector the buried faults are classified as “held to be active” on the basis of data concerning the subsurface deposits, hydrogeological anomalies and evolution of the paleodrainage system. 33..33.. sseeiissmmootteeccttoonniicc cchhaarraacctteerriissttiiccss the information on earthquakes occurring from the year 1000 to 2000 in the modena and reggio emilia provinces and surrounding areas can be found in rercnr (1980), postpischl (1985), boschi et al. (1995), camassi & stucchi (1996), gruppo di lavoro cpti (1999) and boschi et al. (2000). as for recent seismic activity, the data can be taken from zucchi (1995, 1996, 1997, 2000, 2001): these papers contain data recorded by the local seismic network which is connected to the italian seismic network of the national institute of geophysics and volcanology (ingv). the publication making up the national reference for seismogenetic zonation is that by meletti et al. (2000). from this paper it results that the modena and reggio emilia provinces fall within the area subject to the passive sinking of the adriatic lithosphere under the chain system of the northern apennines. in particular, the study area is longitudinally subdivided into three belts parallel to the main structural trend of the northern apennines (nw-se) (fig. 2). the outermost belt (belonging to seismogenic zone no. 39) corresponds to the ferrara folds. these tectonic structures, buried under the po plain quaternary sediments, gave rise to a number of earthquakes, sometimes with damage and loss of lives both in historic times (years 1346, 1570 and 1832) and in the recent past (1996). the correggio earthquake of 15 october 1996, which had a 4.8 magnitude and a depth of 12 km (di giovanbattista & tyupkin, 1999; borghini et al., 2000), could be associated with the correggio fault (fault no. 41 in fig. 3). also the intermediate belt (zones nos. 30 and 35) is characterised by prevalently compressive structures. it partly corresponds to the emilia folds which form another thrust system buried under the quaternary sediments of the po plain. some other compressive structures crop out in the hill-foot sector. the earthquakes are mostly concentrated in a narrow zone which coincides with the plain-hill boundary: among the most intense events, the earthquakes of 1438 (viii mcs), 1501 (viiiix mcs), 1547 (viii mcs), 1818 (vii-viii mcs) and 1971 (vii-viii mcs) should be mentioned. the innermost belt (zones nos. 29 and 34) is located along the highest sector of the chain and is characterised mainly by extensional faults. some fault-plane solutions show that also the present seismic activity is extensional (frepoli & amato, 1997, 2000). this seismogenetic belt corresponds to the lowest seismicity portion d. castaldini et al. 235a methodology for medium scale ... fig. 4 earthquake-induced landslides (i.q. = 3) in the modena and reggio emilia provinces. legend: f) first time effect; i) intensity (mcs); m) magnitude; h) depth of focus (km); i.q.) information quality index; d) distance epicentre/effect; i.t.) interval time between earthquake and induced effect (cont. = contemporary). frane sismoindotte (i.q. = 3) nelle province di modena e reggio emilia. legenda: f) primo innesco; i) intensità (mcs); m) magnitudo; h) profondità ipocentrale (km); i.q.) indice di qualità dell'informazione; d) distanza epicentro/effetto; i.t.) intervallo temporale (giorni) terremoto/frana sismoindotta (cont. = contemporaneo). of the study area. the belt affected by higher-magnitude earthquakes in this sector of the northern apennines corresponds to the garfagnana and lunigiana areas located on the tyrrhenian side (zone no. 28). it is characterised by very evident extensional features. in the past this area was affected by higher-magnitude quakes; the most destructive events occurred in 1837 and 1920, both reaching an intensity of ix-x mcs in the epicentre area, and caused landslides also in the modena and reggio emilia apennines. as for the territory of the modena and reggio emilia provinces, the maximum intensity observed for the seismic events from the year 1000 to 1992 ranges from < v to vii-viii mcs (cf. camassi et al., 2000), with an expected intensity of vi-vii mcs in a return time of 475 years (cf. slejko et al., 1998). 33..44.. eeaarrtthhqquuaakkee--iinndduucceedd ssuurrffaaccee eeffffeeccttss within the framework of the research an inventory of earthquake-induced surface effects in the modena and reggio emilia provinces was prepared. it was based of the compilation of maps of earthquake-induced surface effects and of easy-to-consult surface effect data sheets (see castaldini et al. 2000). earthquake-induced surface effects have been isolated by consulting historical catalogues and archives, public authorities’ offices, research agencies, research projects and scientific reviews. as regards scientific reviews, several authors investigated the geomorphological effects caused by earthquakes in the study area: pellegrini & tosatti, (1982); zecchi (1987); mazzini (1994 and 1995); romeo & delfino (1997); casali & castaldini (1998); castaldini et al. (1998b); genevois et al. (2000) and bertolini & pellegrini (2001). in this research, the identification of earthquakeinduced surface effects was carried out according to the method proposed by genevois et al. (2000). according to mazzini (1995), as a discriminating tool, an information quality index (i.q.) was defined for the evaluation of the correspondence between earthquakes and induced surface effects. in the cases of a good correspondence, an i.q. = 3 has been attributed; in the cases of a fair correspondence an i.q. = 2 and in the case of any correlation an i.q. = 1. this research led to the collection of several surface effects occurring in spatial-temporal relationship with seismic events. nevertheless, only 12 well documented landslides can be reliably attributed to seismic events (i.q.= 3) (fig. 4). to some others surface effects, possibly due to seismic events (landslides, mud vulcanoes’ activity, fissures, ground deformation), an i.q. = 2 or 1 has been attributed. from the seismotectonic standpoint, earthquake-induced landslides (i.q.= 3) are nearly all (11 out of 12) located in the seismogenetic zones nos. 29 and 34 (cf. fig. 2) which correspond to the lowest seismicity portion of the study area. the triggering of landslides was due to seismic events occurring in the surrounding seismogenetic zones characterised by higher seismicity. in particular, seven landslides (nos. 3 to 9 in fig. 4) were triggered by the strong (x mcs and 6.5 magnitude) earthquake which struck garfagnana and lunigiana (seismogenetic zone no. 28 in fig. 2) on 7 september 1920. all the landslides were triggered by earthquakes with intensity ranging from ivv to x mcs degrees (3.3 to 6.5 magnitude) with epicentres some 15 to 30 km away. as regards the type of earthquake-induced landslides, they are mainly complex or slide-type movements. the rock types involved are essentially flysch, clay, clay shale and debris. most of these movements are reactivations of dormant landslides. the fact that earthquakes with <4 magnitude could trigger landslides even at distances of tens of km may seem strange in the light of more or less recent wellknown studies on earthquake-triggered landslides (e.g. keefer, 1984; bommer & rodriguez, 2002). nevertheless, as already pointed out by other authors (e.g. mazzini, 1995; genevois et al., 2000), this fact should not to be considered as anomalous, since a minimum triggerring threshold cannot be defined in an absolute sense. in fact, it is well known that slope stability is a function of many variables that are not less important than local magnitude. investigations aiming to assess the role of precipitation in triggering earthquake-induced landslides are now in progress (see castaldini et al., 2001). 44.. ssttuuddyy mmeetthhooddoollooggyy iinn mmooddeennaa aanndd rreeggggiioo eemmiilliiaa pprroovviinncceess the attempt to analyse and quantify the most important parameters which influence and condition the local effects, or site effects, requires complex studies which cannot be carried out over a vast, geologically complex and geomorphological varied area as the study area, mainly because of economic and time reasons. moreover, as previously stated, the principal institutional task of the provinces, in the matter of territorial planning, is to provide directions to the municipalities, which are the administrative bodies devoted to design the land use planning at a detailed scale (prg: municipal general regulation plane, psc: municipal structural plane; poc: municipal operative plane). for these reasons, the medium-scale investigations here proposed correspond to qualitative and not quantitative studies. considering the scale of this study, the use of essentially bibliographic data and the qualitative approach given to this research, the methodology here described may be classified as “a general zonation methodology” or, even better, a “grade 1 zonation” in the sense of tc4 (1999). this section illustrates the medium scale studies carried out in the modena and reggio emilia provinces with the elaboration of several maps (1:50,000 scale), according to the general scheme of fig. 5. in particular, this part is limited to a summarised illustration of the studies carried out in an apennine sector with the example of the zocca-rocca malatina area. the case-study is located in the mid-apennines of the modena province on the right-hand side of the r. panaro between the hamlets of zocca, to the south, and rocca malatina, to the north (figs. 6 to 10). the western and southern zones correspond to the slopes facing the r. panaro (which is located at about 200 m a.s.l.) and torrent missano (a right tributary of the r. panaro). the zone between zocca, samone and rocca malatina (central and eastern sector) is a sort of plateau with mild landforms. this sector attains altitudes slightly excee236 d. castaldini et al. ding 800 m a.s.l.: rocca malatina rises at about 530 m and zocca at 750 m. several hamlets are also found in this sector of the modena apennines (gainazzo, montecorone, missano and montealbano). the collected data were organised in order to be retrieved in a geographic information system (gis). the procedures for the implementation of the “maps of seismic susceptibility” were obtained by means of gis operations starting from the geological map, geomorphological map and the data base of the inventories of quaternary active faults and earthquake-induced surface effects. 44..11.. ssttuuddyy ooff tthhee ggeeoollooggiiccaall cchhaarraacctteerriissttiiccss the geological characteristics of the apennine sector where the example area is located are illustrated in regione emilia-romagna (2002) and have been briefly outlined in 3.1. in the zocca-rocca malatina area (fig. 6) two groups of very different types of rocks crop out: one belongs to the ligurian allochthonous sequences and the other to the unconformably overlying epiligurian sequence. the ligurian sequences, which crop out on the slopes facing the r. panaro and t. missano, can be subdivided into two parts: a lower one called “pre-flysch formations” (cretaceous) and an upper part called tresinaro valley sequence (upper cretaceous to paleocene-lower eocene?). the “pre-flysch formations” are represented by three dismembered shaly rock-units: i) scabiazza sandstones; ii) cassio varicoloured shales; iii) palombini shales. the tresinaro valley sequence is represented by an helminthoid flysch unit belonging to the monte cassio flysch and the overlying viano shales. the former is entirely made up of calcareous turbidites, the latter of varicoloured shales. in this area numerous landslides and slope deposits are also present. the epi-ligurian sequence constitutes the upper part of the example area relief and lies on the above described ligurian rocks owing to a marked angular unconformity. in the area depicted in fig. 6 this sequence is mainly represented by two different rock units (the 237a methodology for medium scale ... fig. 5 scheme of medium-scale studies (1:50,000 scale). schema degli studi a media scala (scala 1:50.000) pantano and cigarello formations) belonging to the bismantova group. the pantano (upper burdigalian?lower langhian) formation is made up of fine to very fine-grained arenites in medium to very thick tabular beds or by cross-bedded, fine to coarse-grained biocalcarenites and arenites. the cigarello formation (lower langhian-serravallian) lies on the pantano formation and consists of light grey, massive silty-sandy marls. the bismantova group is separated from the underlying older epi-ligurian units by a regional unconformity. the latter are mainly represented by scattered outcrops of clayey and marly rocks belonging to the contignaco, 238 d. castaldini et al. fig. 6 geological map of the zocca-rocca malatina area. the black zones correspond to the main hamlets. carta geologica dell’area di zocca e rocca malatina. le zone in nero indicano i principali centri abitati. antognola, ranzano and monte piano formations. colluvial deposits, a few metres thick, locally cover the epi-ligurian sequence. from a macrostructural viewpoint, the area is affected by important fault systems with vertical and horizontal displacements; the faults are n-s to sswnne oriented. 44..22.. ssttuuddyy ooff tthhee lliitthhoo--tteecchhnniiccaall cchhaarraacctteerriissttiiccss the different rock units cropping out in the modena and reggio emilia provinces have been described and assembled on a litho-technical basis, taking into account the parameters concerning composition, texture, degree of cementation, type of stratification and state of joints. in a first phase, a legend for the litho-technical units was compiled in respect to the rock types present in the study area starting from the geological map (see fig. 5); eleven litho-technical units, which are described below, were thus defined. ul1) flysch and competent multilayer units. they are multilayered units made of high-competence strata alternating with low-competence strata. even if they might display either ductile or brittle deformation patterns, the original strata are preserved and visible with the competent ones often prevailing on pelitic or marly layers. rocks belonging to this unit can be considered as rock masses showing good to very good strength characteristics. ul2) arenaceous flysch units. they correspond to the tuscan tertiary flysch formations which are mainly made up of layers of turbiditic sandstones alternating with fissile beds of marly pelites. the ratio between high competence levels and low competence levels is usually higher than 1. these rocks generally show from good to very good strength characteristics and good stability of the slopes. ul3) mainly arenaceous or arenitic units. this set groups all the units characterised by a prevalently arenitic, quartz-feldspar or calcarenitic composition. their cementation degree is variable but their competence is always high, and they generally show good strength attitude. ul4) heterogeneous units. the formations showing a lithologically heterogeneous composition are grouped in this unit. they are mainly made up of silty sandy marls and marly clays with pervasive slickensidelike scaly surfaces. they form rock masses of generally fair to poor strength depending on the degree of weathering. ul5) evaporite units. this rock type is found only in the reggio emilia apennines (triassic evaporites cropping out in the upper secchia valley and messinian evaporites cropping out along the apennine margin). these rocks generally show fair to poor strength characteristics owing to the solubility of some evaporite minerals. ul6) mainly pelitic-marly units. these units correspond to the rocks with a prevalently marly composition. they differ from the formations of litho-technical unit no. 4 because they show a globular fracturing with lower heterogeneity. for this reason they also show better strength characteristics when they are fresh, though this feature can locally lead to collapses due to weathering. ul7) ophiolites. ophiolitic rock masses are incorporated within the ligurian formations (they are therefore generally included within unit no. 9). only the ophiolite outcrops, representable at a 1:50,000 scale, are mapped. they show fair to good strength characteristics depending on mineral composition and degree of weathering. ul8) mainly argillaceous units. the lithostratigraphic units with a prevalent clayey-marly composition are grouped under this definition. they correspond mostly to the so called “argille azzurre” (blue clays) cropping out along the apennine margin. in a fresh state these rocks shows good strength characteristics, but they are deeply affected by water content changes. in the weathered state these rocks show poor to very poor strength characteristics. ul9) argillaceous units with block-in-matrix fabric. this litho-technical unit assembles all the lithostratigraphic units showing a mostly clayey composition, which also enclose rock blocks. they may be described as “chaotic units”. this unit comprehends most of the formations named in the not so recent literature as: argille scagliose, alloctono indifferenziato, complesso caotico, etc. the rocks of this unit display good geotechnical characteristics when not weathered; nevertheless, their argillaceous composition favours weathering processes up to considerable thicknesses with water percolation followed by cycles of plasticisation and desiccation. these processes make these soils extremely prone to displacements. ul10) surface deposits. superficial deposits of various origin (alluvial, eluvial, colluvial, glacial, slope, etc.) are grouped in this unit. they are heterogeneous materials with characteristics which may vary from very soft soils (lacustrine deposits) to loose grain deposits (e.g., slope deposits). these soils are distinguished on the basis of particle-size distribution which ranges from boulders to gravel (ul10a) and from sand to clay (ul10b). ul11) landslides. deposits and accumulation of materials genetically ascribed to slope movements are assembled in this group. among the above mentioned litho-technical units, only the following ones crop out in the study area: a) flysch and competent multilayer units (ul1); b) mainly arenaceous or arenitic units (ul3); c) heterogeneous units (ul4); d) mainly pelitic-marly units (ul6); d) argillaceous units with block-in-matrix fabric (ul9); e) surface deposit units distinguished on the base of their texture (ul10); f) landslides (ul11). anyhow, a “lithotechnical map” is not shown for the example area since it would be practically identical to the “simplified litho-technical map”, which will be discussed further on (fig. 7). it is known that buildings with similar structural features but built on different rocks or soils, even if located at a short distance from each other, react differently to earthquakes. this phenomenon is due to the so called local effects that can be referred to two different groups of causes: i) seismic amplification; ii) seismic instability. these phenomena are well described and analysed in literature (see for example: medvedev, 1965; borcherdt, 1970; siro & bigi, 1983; siro, 1985; phillips & aki, 1986; géli et al., 1988; margottini et al., 1992; ambraseys et al., 1996; pergalani, 1996; crespellani et al., 1996 and 1998; state of california, 239a methodology for medium scale ... 1997; lanzo, 1999; madiai, 1999; tc4, 1999; pergalani et al., 1998, 1999 and 2000; luzi et al., 2000; regione toscana, 2000; marcellini & maugeri, 2001a and 2001b; paolucci, 2002). local seismic amplification broadly consists in a local increase of the seismic waves amplitude relative to a reference site. this effect of wave amplitude amplification can be caused either by stiffness contrast between the bedrock and the superficial deposits or by difference in rigidity between the rocks in the investigated area and the rocks in the reference site. moreover, some particular morphological conditions can also locally focalise seismic energy giving rise to a seismic wave amplification effect. for example, among many relevant remarks in his very recent study, paolucci (2002) states that in the presence of marked ground roughness the factor of amplification of seismic waves typically varies between 1.5 and 2. in detailed studies of seismic microzonation (e.g.: pergalani, 1996), the effect of seismic amplification was studied assuming as reference site a particular 240 d. castaldini et al. fig. 7 – “simplified litho-technical map” of the zocca-rocca malatina area. the black zones correspond to the main hamlets. the legend is referred to the modena and reggio emilia apennines. “carta litotecnica semplificata " dell’area di zocca e rocca malatina. le zone in nero indicano i principali centri abitati. la legenda si riferisce all'area dell'appennino modenese e reggiano. location closer to the study area which might have an outcropping bedrock and almost subplanar morphology. in consequence of this detailed approach, the litho-technical unit forming the bedrock of the reference site can change depending on the geological nature of the study area. on the contrary, in this research, according to the studies aim, a conservative approach was adopted. referring to the classical work by medvedev (1965) a hypothetical reference site with a flat morphology and a 241a methodology for medium scale ... fig. 8 “geomorphological map” of the zocca-rocca malatina area. the black zones correspond to the main hamlets. “carta geomorfologica” dell’area di zocca e rocca malatina. le zone in nero indicano i principali centri abitati. granite bedrock was chosen (to which a 0 value of potential seismic amplification was attributed). medvedev (1965) stated that an increasing seismic intensity may occur in areas where rocks softer than granite (reference rock) crop out. starting from this assumption, the seismic amplification may be qualitatively mapped considering the fact that it is generally more intense with the decrease of certain physical characteristics of the bedrocks and superficial deposits (especially stiffness and density). compared to granite, the simplified litho-technical units previously defined (see section 4.2 and fig. 7) can be ranked by considering the strength characteristics as qualitative measure of their stiffness. consequently, areas with different bedrock stiffness can be ranked, for their propension to local seismic amplification.since all rocks and soils cropping out in the modena and reggio emilia provinces are characterised (from a qualitative viewpoint) by values of stiffness lower than those pertaining to the granite, it results that all the territory of the study area may be potentially subject to relative amplification effects. since some of the previously defined litho-technical units show very similar stiffness characteristics, with respect to granite (considering also the work scale), they were grouped together. practically, in a second phase a legend for a “simplified litho-technical map” was elaborated reducing from eleven to five the litho-technical units (see fig. 7). in detail, the ul1, ul2 and ul3 litho-technical units were grouped together in the simplified litho-technical unit n. 1 ( sl1, rocky units) as they generally show from good to very good strength characteristics (depending on their stiffness). the ul4, ul5, ul6, ul7 and ul 8 litho-technical units were grouped together in the mixed units (sl2) as they show generally lower stiffness then the above mentioned units of sl1. the argillaceous units with block-in-matrix fabric (ul9), that often show a thick superficial weathered cover subject to rapid change in water content was considered less stiff than units of sl2 and it was defined as sl 3. finally the superficial deposits (ul10) and the landslide deposits (ul11), which show the poorest strength characteristics relative to the reference rock and also relative to the other ones, were classified as simplified litho-technical units sl4 and sl5, respectively. the “simplified litho-technical map” of the example area is shown in fig. 7. the example area may be subdivided into two separate sectors: i) a western and southern sector (corresponding to the slopes facing the r. panaro and t. missano); ii) a central and eastern sector (area between zocca, samone and rocca malatina). the first sector is essentially characterised by the presence of argillaceous units with block-in-matrix fabric (sl3) and landslides (sl5). on the bottom of the r. panaro and at the boundary with the eastern sector, surface deposits with texture from boulders to gravel (sl 4a) crop out. in the central and eastern sector the rocky units (sl1) made up of flysch and competent multilayer units (ul 1) and mainly arenitic units (ul 3) extensively crop out. locally, mixed units (sl2) (represented by heterogeneous units, ul 4, and mainly pelitic-marly units, ul 6), surface deposits with sandy-silty texture (sl 4b) and small superficial landslides (sl5) crop out. 44..33.. ssttuuddyy ooff tthhee ggeeoommoorrpphhoollooggiiccaall cchhaarraacctteerriissttiiccss the aim of this section is the identification of the geomorphological setting of the study area. the genesis, degree of activity of geomorphic processes, related landforms and deposits (with morphometric characteristics) must be distinguished in a preliminary phase. in the example area, the landforms and deposits identified may be mainly classified according to the following systems or groups of morphogenetic factors and processes (fig. 8): landforms and deposits due to running water; slope landforms and deposits due to gravity; structural landforms; anthropogenetic landforms, karsttype landforms. the bedrock is not shown since it is already represented in the “simplified litho-technical map” (fig. 7). also from the geomorphological viewpoint, the study area may be subdivided into two separate sectors, since the relief forms have been strictly conditioned by the characteristics of the outcropping rocky units: i) a western and southern sector ; ii) a central and eastern sector. in the first sector (slopes facing r. panaro and t. missano) the most relevant morphogenetic processes consist of active or dormant earth flows and rotationaltranslational slides which affect the shaly rocks. the various landslide bodies are bounded by several gullies which further contribute to slope instability owing to their accentuated erosion. the central and eastern sector (area between zocca, samone and rocca malatina), where arenaceous and arenaceous-pelitic formations crop out, only small zones seem to be affected by active degradational processes. this sector is higher in altitude (from about 500 to 800 m) than the western and southern sector (from about 500 to 200 m): on the whole this area is a sort of plateau with mild landforms. in the area, narrow v-shaped valleys and wide flat-floored valleys (partially filled by prevalently colluvial deposits) are found; although the wide flat-floored valleys are not shown by a specific symbol, the colluvial deposits make them easily identifiable in fig.8. karst type concavities are also present. the connection of this sector with the slopes facing the r. panaro and t. missano is made evident by the presence of scarps and long and narrow ridges. from studies recently carried out in the apennine sectors (pergalani et al., 1998 and 2000; luzi et al., 2000) it results that considerable amplifications of seismic waves take place in correspondence of detrital covers overlying a hard bedrock thicker than 10 m and that particularly narrow and elongated ridges and scarps higher than 20 m might cause a considerable focalisation of seismic waves with a consequent increase of seismic intensity. moreover, in the presence of loose deposits showing poor geotechnical characteristics (deposits with texture from silt to clay), serious settlements or even loss of the soils’ bearing capacity may occur, irrespective of their thickness and therefore of the effect of seismic amplification. other situations of potential seismic instability are linked to both active and dormant landslides. another possible hazard element linked to earthquakes is given by the presence of neotectonic faults: the resulting damage is due not so much to high dynamic stress but rather to possible differential displacements which may occur along these structural discontinuities. 242 d. castaldini et al. 243a methodology for medium scale ... fig. 9 – “simplified geomorphological map” of the zocca-rocca malatina area. the black zones correspond to the main hamlets. the legend is referred to the modena and reggio emilia apennines. “carta lgeomorfologica semplificata ” dell’area di zocca e rocca malatina. le zone in nero indicano i principali centri abitati. la legenda si riferisce all'area dell'appennino modenese e reggiano. therefore, in a second phase, a legend for the “simplified geomorphological maps” was properly elaborated in respect to the landforms and deposits present in the modena and reggio emilia apennines (see fig. 9). thus, landforms and deposits were distinguished to identify geomorphological situations which may give local responses to seismic acceleration and/or earthquake-induced instability. in this legend, the genesis of landforms and deposits was omitted (since it is not relevant for seismic susceptibility) whereas importance was given to the degree of activity, to morphometric characteristics (height, thickness, texture) and to topographical position (on valley bottom or flat areas, on slope). for example, the deposits were grouped on the basis of their thickness (from 1 m to 10 m, higher than 10 m). they were further distinguished on the basis of their particle-size characteristics (from boulders to gravel and from sand to clay) and their location (on slopes, valley floors or flat areas). a part from their activity (which is an important characteristic from the stability standpoint), scarps were distinguished according to their height (higher or lower than 20 m) which is a discriminating parameter for seismic amplification. furthermore, slope movements, in particular earthquake-induced landslides (resulting from the data base of earthquake-induced surface-effects inventory), and quaternary faults were considered. the quaternary faults, active or held to be active, are derived from the data base of the quaternary active fault inventory. nevertheless, it should be specified that in the “simplified geomorphological maps” the quaternary faults are shown only in the stretches corresponding to faults represented in the geological maps. the “simplified geomorphological map” relative to the example area is shown in fig. 9. in this map, the landslides and the surface deposits located on the slopes facing the r. panaro and t. missano stand out. in the connection belt to the central and eastern sector (area between zocca, samone and rocca malatina) morphological elements prone to seismic amplification are evident, such as narrow and long ridges and scarps more than 20 m high. in the central and eastern sector, areas prone to seismic instability and/or amplification are found in correspondence with small superficial landslides and fine superficial deposits less then 10 m thick. 44..44.. ssttuuddyy ooff tthhee sseeiissmmiicc ssuusscceeppttiibbiilliittyy cchhaarraacctteerriissttiiccss in the study of seismic hazard applied to territorial planning, it is very important to identify those areas which may suffer more than others from the effects of an earthquake. therefore, the aim of this section is the identification of the areas and elements prone to seismic amplification and/or earthquake-induced instability on the basis of the “simplified litho-technical map” and of the “simplified geomorphological map” (see fig. 5). the first step is the identification of the areas prone to seismic amplification that show morphological and/or litho-technical features potentially causing amplification. as previously illustrated, the medvedev (1965) conservative approach was adopted. thus, considering a 0 amplification for the reference hypothetical site (granite bedrock), five classes of relative seismic amplification, from 1 to 5 (from low to high amplification), corresponding to the 5 simplified litho-technical units, were defined. in detail, areas where the rocky units (sl1) crop out were considered as having a low potential of seismic amplification (class 1). this because the rocks belonging to sl1 show (qualitatively) values of stiffness and density lower than granite but higher than other simplified litho-technical units. areas where mixed units (sl2) crop out were considered as having an intermediate-low seismic amplification (class 2). areas with argillaceous units with block-in-matrix fabric (sl3) were considered as characterised by intermediate seismic amplification (class 3). zones with superficial deposits (sl4) were considered as having an intermediate-high seismic amplification (class 4). finally, landslides (sl5) which are made of materials that generally show the lowest values of stiffness and density (relatively to the reference rock and, also, to other litho-technical units) are considered to produce the highest values of potential seismic amplification (class 5). the morphological features causing amplifications (scarps higher than 20 m, narrow and long ridges) are shown with linear symbols. the second step of this section is the identification of the areas prone to earthquake-induced instability. the features causing earthquake-induced instability are shown with zones indicated with letters from a to d according to the following classes of instability: a) stable areas and intermediate stability areas: areas where the characteristics of instability are absent or not mappable; b) potentially unstable areas with possible problems regarding the bearing capacity of soils: valley floors or flat areas with fine surface deposits; c) potentially unstable areas prone to mass movements or rock fall processes or debris detachment: areas below landslide scarps, areas below active scarps of different morphogenesis, clusters of adjacent landslides, surface slope deposits; d) unstable areas prone to mass movements: landslides of different type and activity, areas affected by deep-seated gravitational slope deformations; the earthquake-induced landslides, derived by data base of earthquake induced surface effects, are shown with a particular symbol. the quaternary faults (active or held to be active) are also shown according to the criteria described for the “simplified geomorphological maps”. the final phase consisted in the elaboration of the “maps of seismic susceptibility” by the simple combination of the areas prone to seismic amplification and the areas prone to earthquake-induced instability. this was achieved by carried out simple gis operation. the legend for the “maps of seismic susceptibility” and the map of the example area are illustrated in fig. 10. the classes of seismic susceptibility can be shown as zones with an alphanumeric code defined through the combination of numbers (from 1 to 5) and letters (from a to d), with different colours or with different areal symbols (as in fig. 15). the highest seismic susceptibility is found in correspondence with the zones classified as 5d, 5c and 5b, which means high relative amplification (5) in, respectively, unstable areas prone to mass movements (d), potentially unstable areas prone to mass movement or rock fall processes or debris detachment (c), potentially unstable areas with problems regarding the bearing capacity of soils (b). the lowest seismic susceptibi244 d. castaldini et al. 245 fig. 10 – “map of seismic susceptibility” of the zocca-rocca malatina area. the black zones correspond to the main hamlets. the legend is referred to the modena and reggio emilia apennines. “carta della suscettibilità sismica” dell’area di zocca e rocca malatina. le zone in nero indicano i principali centri abitati. la legenda si riferisce all’area dell’appennino modenese e reggiano. a methodology for medium scale ... lity is found in correspondence with the zones classified as 1a which means low amplification in stable areas or intermediate stability area. obviously, some combinations between amplification degrees and instability classes are not conceptually compatible. for example, combination 1d, that is a low amplification area in correspondence with a landslide area, cannot exist. in the example area (fig. 10) the highest amplification (class 5) is mainly found in correspondence with the numerous landslides which characterise the slopes facing the r. panaro and t. missano. on these slopes argillaceous units with block-in-matrix fabric mainly (sl3) crop out so they are prevalently characterised by intermediate amplifications (class 3). the lower amplification (classes 1 and 2) is marked in the central-eastern sector where rocky litho-technical units (mainly consisting of sandstones, sl1) and mixed units (sl2) crop out. in any case, in this sector an increase of amplification may be locally induced in the following situations: i) in wide flat-floored valleys where fine surface deposits (less than 10 m thick) crop out; ii) in correspondence of the small superficial landslides; iii) in correspondence to narrow and long ridges and scarps higher than 20 m. as concern the earthquake-induced instability (fig. 10) the unstable areas prone to mass movements are mainly found in correspondence with the numerous landslides which characterise the slopes facing the r. panaro and t. missano. in this sector potentially unstable areas, prone to mass movement or rock fall phenomena or debris detachment, are shown below landslide scarps and active scarps as well as in correspondence with surface slope deposits and clusters of adjacent landslides. the central and eastern sector (area between zocca, samone and rocca malatina) is mainly considered a stable area because rocky litho-technical units crop out. there are small unstable zones in correspondence of superficial landslides and, moreover, the wide flat-floor valleys are considered potentially unstable with problems regarding the bearing capacity of soils owing to the presence of less than 10 m thick deposits with a sandy-silty texture. therefore, in the example area the zones with the highest seismic susceptibility (5d and 5c) are the slopes facing the r. panaro and t. missano and those with the lowest seismic susceptibility (1a) characterises the main part of the area between zocca, samone and rocca malatina. it should be pointed out that, according to the goals of the research (see cap. 1) and the working scale (1:50,000), the classification adopted in the “maps of seismic susceptibility” should be considered as approximate (for example, it is not sure whether all the landslide areas might be reactivated by a seismic shock, whereas potentially unstable areas might not coincide with just those shown in the legend). therefore detailed investigations should be carried out in the areas where urban development has been planned. 55.. ffiinnaall rreemmaarrkkss aanndd ccoonncclluussiioonnss this work describes a methodology for implementation of seismic susceptibility maps for assessing seismic hazard, in other words maps of the areas prone to seismic amplification and /or earthquake-induced instability, based on geological and geomorphological studies. the studies here described are qualitative and not quantitative. the choice to adopt a qualitative approach is due to the following reasons: i) study area with large extension, complex geology and different morphological characteristics. in fact, the territory of the modena and reggio emilia provinces stretches over about 5,000 km2, its southern sector is mountainous and hilly whilst its northern sector is flat and the geological characteristics are quite complex. ii) the need to acquire standardised data all over the study area. the parameters chosen in the application of quantitative methodological approaches have to be considered local and, therefore, cannot be extended to areas having different geological and morphological characteristics. iii) short times for carrying out the research. the studies aiming at defining the knowledge on the seismic hazard of the territory of the modena and reggio emilia provinces should have been completed in two years. the methodology here adopted enabled us to define, in a relatively short time and with sufficient reliability, the seismic susceptibility in a vast territory like that of the modena and reggio emilia provinces. the resulting maps (maps of seismic susceptibility) are a sort of “alert maps” and are easily readable also by technicians from public boards. therefore, they can be useful to the provinces administration boards in giving directions in matter of territorial planning to the municipalities. considering the scale adopted (1:50,000), a grade 1 zonation can be attributed to the maps of seismic susceptibility (according to tc4, 1999). these maps are the first maps of seismic susceptibility concerning the whole territory of the modena e reggio emilia provinces. finally, it should be pointed out that, since all the data were stored in a gis and the maps produced are in a digital format, new research results may be easily incorporated. aacckknnoowwlleeddggmmeennttss this article was published with the financial support of cnr-agenzia 2000 (cnrc007e55_005, local co-ordinator doriano castaldini) and of the cerg (european centre on geomorphological hazards of strasbourg, france)(local co-ordinator mario panizza). the research was carried with a convention between the university of modena and reggio emilia and the administration boards of the provinces of modena and reggio emilia. moreover, it was part of the scientific activities of the cerg. the preliminary results of the research were presented by d. castaldini at the 5th romanian-italian 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(2000) rete per il rilevamento della sismicità naturale delle province di modena e reggio emilia: annuario sismico 1997, 1998, 1999. comune di modena, 47 pp. zucchi m. (2001) rete per il rilevamento della sismicità naturale delle province di modena e reggio emilia: annuario sismico 2000. comune di modena, 31 pp. 249 ms. ricevuto il 26 marzo 2002 testo definitivo ricevuto l’8 gennaio 2003 ms. received: march 26, 2002 final text received: januari 8, 2003 a methodology for medium scale ... imp.bosi pplliioo--qquuaatteerrnnaarryy ccoonnttiinneennttaall ddeeppoossiittss iinn tthhee llaattiiuumm--aabbrruuzzzzii aappeennnniinneess:: tthhee ccoorrrreellaattiioonn ooff ggeeoollooggiiccaall eevveennttss aaccrroossss ddiiffffeerreenntt iinntteerrmmoonnttaannee bbaassiinnss ccaarrlloo bboossii,, ffaabbrriizziioo ggaallaaddiinnii,, bbiiaaggiioo ggiiaacccciioo,, ppaaoolloo mmeessssiinnaa && aannddrreeaa ssppoossaattoo cnr istituto di geologia ambientale e geoingegneria, section of roma "tor vergata", roma, italy (e-mail: f.galadini@igag.cnr.it) abstract a stratigraphic framework valid for the pliocene-middle pleistocene continental deposits of the latium-abruzzi apennines has been defined through the correlation of the depositional/erosional events (indicated by stratigraphic and morphologic units, respectively) across seven different intermontane basins. this has been made by comparing the geological evolutions of the different basins. the basic assumption for the correlation of the different events is that climatic factors have conditioned the geological evolution of the investigated sector in a substantially uniform way. uniform climatic conditions have caused similar responses of the basins to the climatic changes. continental deposition in the latium-abruzzi apennines began during the pliocene, prevalently with clayey-silty-sandy lacustrine deposits fed by the clayey-arenaceous flysch into which the landscape was carved at the time of the first continental deposition. the formation of an indented landscape with higher slopes bordering the basins is demonstrated by huge landslide deposits of both arenaceous and calcareous coarse material. sediments related to the second depositional event (early pleistocene) are mainly characterised by a carbonate lithology in slope deposits (slope-derived breccias), in lacustrine (carbonate silts) and fluvial (carbonate gravels) sediments. this is due to the dominant carbonate lithology of the bedrock in the areas experiencing erosion during the quaternary. the third depositional event (related to the lower middle pleistocene) has lithological and sedimentological characteristics comparable to those of the second event. it consists, indeed, of slope-derived carbonate breccias, carbonate silty deposits of lacustrine origin and carbonate gravels of fluvial facies. the fourth depositional event (middle pleistocene) is characterised by the first significant deposition of material of volcanic origin and numerous tephra levels related to the central italy volcanic activity can be detected. chronological constraints for the second depositional event are represented by the reverse paleomagnetic polarity of the deposits, defining ages older than 0.78 ma and by the remains of arkidiscon meridionalis vestinus azzaroli in the l'aquila basin. chronological data for the third depositional event are represented by paleontological remains of equus altidens reichenau and by the association hippopotamus antiquus desmarest/elephas antiquus falc. & cautl. and by the lack of volcanic materials which became widespread after 0.6 ma. the age of the fourth depositional event is constrained by the presence of the tephra levels which define a deposition after about 0.6 ma. the attribution of a pliocene age to the deposits of the first event can only be made on a qualitative basis, since bio-chronological data or other quantitative chronological constraints are not available. in this light, the significant changes which affected the landscape between the first two depositional events seem to indicate that a very long time span passed between them. riassunto viene proposto uno schema stratigrafico per i depositi continentli dell’appenino laziale-abruzzese, fondato su una serie di correlazioni che riguardano le successioni riconosciute da precedenti lavori nelle principali conche intramontane. le successioni sono uniformemente descritte in termini di unità stratigrafiche (del tipo “a limiti inconformi”) e di unità morfologiche, definite come “unità morfo-sequenziali” e rappresentate da superfici relitte di erosione o di accumulo. le correlazioni sono state ottenute mediante un confronto fra le successioni morfologico-stratigrafiche, effettuato sulla base di due presupposti: (i) che l’evoluzione geologica che le ha generate sia condizionata principalmente da fattori in vario modo ubiquitari (clima e sollevamento tettonico) e (ii) che l’interazione fra questi fenomeni si sia realizzata in un’area caratterizzata da una relativa costanza dei principali elementi idrografici. questi presupposti inducono a ritenere che le alternanze di episodi deposizionali ed erosivi si siano sviluppate nelle diverse conche con modalità sostanzialmente simili. le correlazioni ottenute mediante questo confronto hanno portato a definire un’unica sequenza dei principali eventi deposizionali nell’area laziale-abruzzese. l’unità stratigrafica continentale più antica è costituita prevalentemente da depositi lacustri limoso-sabbiosi provenienti quasi esclusivamente da aree costituite dalle sequenze arenaceo-argillose tortoniano-messiniane. il paesaggio nel quale si originava l’unità era quindi molto diverso da quello attuale, dominato dalla dorsali carbonatiche. i bacini di sedimentazione erano verosimilmente caratterizzati da versanti molto acclivi, localmente interessati da imponenti fenomeni franosi che andavano ad alimentare una sedimentazione molto grossolana che si rinviene localmente intercalata ai sedimenti lacustri. gli strati di questa prima unità stratigrafica sono spesso vistosamente deformati. anche se non esistono elementi di diretto interesse cronologico, si può riferire l’unità ad un generico pliocene, soprattutto sulla base dei rapporti con l’unità successiva. questo riferimento è indirettamente avvalorato sia dalla "antichità" del paesaggio circostante, molto diverso da quello attuale, sia dalla deformazione, molto più intensa di tutte le unità successive che hanno di regola un assetto sub-orizzontale. il successivo evento sedimentario ha dato origine a successioni di varia litologia ed ambiente (sabbie e limi lacustri, ghiaie fluviali, depositi più o meno grossolani di versante) a prevalente componente calcarea; questa caratteristica è manifestamente connessa con una alimentazione proveniente da un paesaggio che, a seguito della sempre più profonda erosione delle sequenze terrigene mioceniche, era largamente costituito dalle successioni carbonatiche mesozoiche. l’attribuzione di queste successioni al pleistocene inferiore è giustificato dal rinvenimento, nella conca dell’aquila, di una fauna a vertebrati pre-galeriana, contenente mammuthus meridionalis vestinus. congruenti con questa attribuzione sono anche alcune determinazioni di paleomagnetismo che hanno indicato una polarità inversa. il terzo evento sedimentario ha caratteristiche abbastanza simili a quello ora descritto: se ne differenzia principalmente per la minor frequenza di episodi lacustri e per essere connesso ad una marcata tendenza all’erosione laterale che ha dato origine ad estese spianate i cui residui sono tuttora osservabili nel paesaggio. gli unici vincoli cronologici sono rappresentati da resti di equus altidens, rinvenuti nella conca del fucino e di hippopothamus antiquus e di elephas antiquus in quella del tirino. questi ritrovamenti, unitamente alla mancanza di significativi apporti in materiale vulcanici, inducono ad attribuire l’unità al pleistocene medio. il quarto evento sedimentario è caratterizzato dalla prima comparsa di importanti apporti di materiale vulcanico che danno spesso origine a sequenze di strati tufitici: l’età è ancora meso-pleistocenica in quanto precedente ai grandi apparati fluvio-glaciali del pleistocene superiore. keywords: plio-quaternary, continental stratigraphy, paleoenvironments, central italy. parole chiave: plio-quaternario, stratigrafia continentale, paleoambienti, italia centrale. il quaternario italian journal of quaternary sciences 1166(1bis), 2003, 55-76 56 c. bosi et al. iinnttrroodduuccttiioonn plio-quaternary stratigraphic frameworks are fundamental to chronologically constrain geological paleoevents which have deep implications in neotectonics and the reconstruction of recent paleoenvironments. the stratigraphic reconstructions are, however, reliable and based on tested methodologies if related to marine environments, while they are uncertain and often based on not consolidated methodologies if related to continental environments. although the above mentioned problems are sometimes unsurmountable, the object of the present paper is the definition of the continental stratigraphy of a large sector of the latium-abruzzi apennines (fig. 1), with the perspective of drawing a chronological framework for neotectonic reconstructions. the present work represents an update of the papers by bosi (1989) and bosi and messina (1991) and gathers the new knowledge supplied by investigations performed during the last ten years. due to the problems above mentioned, the discussion on the methodology adopted in the study of the continental stratigraphy is fundamental, particularly for the correlation of the successions through the different basins. for this reason a specific section will be entirely dedicated to this aspect. the proposed stratigraphic scheme of the latium-abruzzi apennine continental stratigraphy is directly linked to the methodological aspects above mentioned. therefore, the discussion of the general scheme and of the innovative aspects (with respect to the previous works) will follow the methodological discussion. the general stratigraphic scheme will also represent a sort of reference framework for the following sections, dedicated to the stratigraphic description of the investigated basins. these sections are related to the basins where researchers of the former istituto di ricerca sulla tettonica recente (presently part of the istituto di geologia ambientale e geoingegneria) have worked in the last years. for each investigated basin we cited reference studies. these studies have, however, different characteristics. in some cases they are monographies about specific basins (e.g. zarlenga, 1987; bertini and bosi, 1993, on the fucino basin and the middle aterno valley, respectively). in other cases, monographic studies are lacking and therefore stratigraphic data can be derived from works at the regional scale (e.g. demangeot, 1965; galadini et al., 2003, on the l'aquila basin and the turano valley, respectively). in one case (turano valley), due to the scarcity of published data, we mentioned a degree thesis (melchiorri, 1987). studies related to specific aspects of the recent geological evolution (e.g. galadini and messina, 1994; barbieri et al., in press, on the neotectonics of the fucino plain and the volcanic activity in the piana del cavaliere area, respectively) have also been mentioned. papers on specific sectors of the reported basins or to outcrop-scale stratigraphies have been referred if they seems particularly significant for the purpose of our work (e.g. bertini and bosi, 1976; blumetti et al., 1996, for the fucino and salto basins and the l'aquila basin, respectively). stratigraphic data on intermontane basins of the latium-abruzzi apennines investigated by researchers of other institutes will be summarised in only one section. in the concluding remarks some implications for neotectonics and paleoenvironmental investigations will be outlined 1. fig. 1 location map of the investigated area (latium-abruzzi apennines). 1this paper is dedicated to the stratigraphy of the pliocenemiddle pleistocene. for this reason we invite to find the available information on the late pleistocene-holocene stratigraphy of the investigated area in the numerous works made by the researchers of enea-casaccia (e.g. giraudi, 1994, 1995, 1996, 1998; giraudi and frezzotti, 1997). ggeeoollooggiiccaall ffrraammeewwoorrkk ooff tthhee cceennttrraall aappeennnniinneess the building of the central apennines results from the superimposition of the extensional tectonics to the compressive one since the late cenozoic. the latter is due to the progressive ne migration of the apennine arc related to the well-known flexural retreat of the lithosphere plate located in the adriatic sea (malinverno & ryan, 1986; royden et al., 1987; patacca et al., 1990; doglioni, 1991). contemporaneous opening of the tyrrhenian basin is due to rifting processes west of the apennine chain (e.g., faccenna et al., 1996; jolivet et al., 1999). while compressive structures affected the progressively migrating apennine front and rifting occurred in the tyrrhenian area, extensional tectonics affected the apennine chain (e.g. meletti et al., 1995; cavinato and de celles, 1999; ghisetti and vezzani, 1999), causing the displacement of the pliocenequaternary continental sediments (e.g. cnr-pfg, 1987) and the formation/evolution of intermontane basins (fig. 1). pliocene deposits, mainly represented by lacustrine facies and huge landslide episodes (the so-called "megabreccias") testify to the final emersion of the apennine chain from the sea. the ne migration of this structural system is well recognised for the compressive structures, based on the fact that progressively younger thrusts affect the italian peninsula towards ne (patacca et al., 1990). presently, the active compressive front is located in the adriatic sea along the peninsula and in the po plain in the northern apennine sector, according to the view by patacca et al. (1990). in contrast, more recent works suggest that thrusting and related folding is no more active along the apennines (e.g. di bucci et al., in press and related bibliography). progressively ne shifted intra-apennine extensional domains have also been hypothesised (e.g. lavecchia et al., 1994). the lack of a detailed stratigraphic framework related to the continental facies, however, has prevented the proposal of reliable chronological constraints for the plio-quaternary structural evolution of the intra-apennine extension. the persistence of the extensional activity in the apennines is documented by the numerous works on active tectonics and paleoseismology (e.g. pantosti et al., 1996; galadini and galli, 1999 and reference therein) and by the occurrence of earthquakes with m>6 (e.g. working group cpti, 1999). mmeetthhoodd ooff aannaallyyssiiss ooff tthhee pplliioo-qquuaatteerrnnaarryy ccoonnttiinneennttaall ssuucccceessssiioonnss the reconstruction of the continental stratigraphy at the regional scale results from fragmented information, due to the scarce lateral continuity of the depositional environments and to the intense erosion which usually affects continental areas. moreover, the chronological definition of continental successions is often hindered by 1) the scarcity of the fossil remains which is evident if a comparison with the amount of dating fossils of the marine environment is made and 2) the limit of applicability of methods for obtaining numerical datings (both in terms of material suitable for dating and in 57plio-quaternary continental deposits ... terms of chronological intervals covered by the different methods). due to these problems, since the 80s a method for correlating the continental geological history of different basins has been elaborated and applied to the latium-abruzzi apennines (see fig. 1 for location). procedures and results have already been published in the works by bosi (1989) and bosi and messina (1991). this approach is based on 1) the reconstruction of the depositional/erosional history of single intermontane basins and 2) the comparison of the successions of events which characterised the different basins of the investigated region. both points are based on the assumption that the traces of the depositional/erosional activity are roughly representative of the real geological evolution of a certain basin, if the geological history is defined through chronological steps of hundreds thousand years. the reliability of this assumption is corroborated by the evident comparability of the geological events which affected the different investigated basins (see below). as for point 1, we define the succession of the erosional and depositional events which conditioned the deposition of lithosoma over erosional surfaces, usually embedded one into the other (e.g. fig. 2). this kind of morphologic and stratigraphic relationship has been observed in all the investigated basins. the resulting landscape is made of a succession of terraced landforms, related to the top depositional surfaces of the lithosoma and/or to erosional surfaces carved into other lithosoma or the marine substratum. the comparison mentioned at point 2 is aimed at defining chronological relationships between depositional/erosional events across the different basins. the reliability of the correlation of events throughout a region is fostered by the persistence through time of the main basins and of the main portions of the hydrographic network. this persistence indicates that the terraced succession of the single depressions has to be primarily related to the climatic history of the region. this history has to be considered common to the investigated area, considering its limited extension (fig. 1). the correlation of the depositional units and the related erosional/depositional landforms across basins (the oldest with the oldest, the youngest with the youngest, etc..) is consistent with the sparse available chronological data (paleontological findings, paleomagnetic data, the presence of sedimentary materials related to the post-early pleistocene volcanic activity, see below). the correlations are also supported by other qualitative similarities regarding: 1) the number of depositional events alternating with erosional phases in adjacent basins, 2) the sedimentological and paleoenvironmental characteristics of depositional units belonging to different basins, 3) the intensity of the deformation affecting the depositional units; 4) the relationship between certain deposits and the landscape (e.g. the attitude of slope-derived breccias in comparison with the morphology of the present slopes). the procedure above described (with the evident limits due to the fragmentation of the geological information) permits to define geological events which are ubiquitous across the different basins of a region. as a result of this approach, the morpho-stratigraphic schemes we obtained for each basin (fig. 2) define the geological evolutions in terms of depositional and erosional events. these schemes are much more informative than 58 c. bosi et al. fig. 2 morpho-stratigraphic schemes of the investigated basins in the latium-abruzzi apennines. numbered columns define the different depositional events. 59 simple stratigraphic columns. the latter, indeed, do not define the "geomorphic role" of the continental evolution, since they do not indicate the fundamental processes of terracing, or the most significant areal erosional surfaces, or the depositional top surfaces, thus limiting the vision of the areal geological-geomorphological evolution. an example of correlation among depositional/erosional events of different basins contributes to cast light on the adopted procedure. this case is represented by the first continental sedimentary event which affected a number of intermontane basins of the latium-abruzzi apennines. aspects common to the different basins are: 1) this event marks everywhere the earliest deposition following the orogenic phase in the chain axis area (the continental deposits unconformably cover the marine substratum, see for example bertini and bosi, 1976 for the salto valley); 2) the lower portion of the succession (directly overlaying the marine substratum) is characterised in all the basins by clayey-sandy deposits (lacustrine environment) fed by the miocene clayey-arenaceous flysch; 3) the carbonate clastic deposition becomes predominant towards the upper part of the succession in all the investigated basins; 4) a strong tectonic deformation affects the deposits (which are tilted up to 40° and intensely faulted) in all the basins before the deposition of younger units which unconformably cover the older ones; 5) an erosional phase is in all the basins indicated by an erosional surface representing the base of the subsequent units. the five points suggest that the first depositional episodes in the different intermontane basins, with the similar characteristics above mentioned, can be related to a synchronous depositional event. obviously, sinchroneity has to be intended as chronological comparability of events within a time span of several 0.1 ma (which is the adopted "chronological scale"). the definition of common aspects in the depositional/erosional histories of basins implies that most of the field research has to be addressed to the reconstruction of geological evolution of basins (fig. 2). the chronological aspect, as indicated at the beginning of this section, is a further problem of continental stratigraphy. in the investigated region, key biochronological data are represented by arkidiscon meridionalis vestinus azzaroli (early pleistocene2; azzaroli, 1983) of the l'aquila basin, elephas antiquus italicus osborn (middle pleistocene; maini, 1956) of the middle aterno valley, equus altidens reichenau (middle pleistocene; blumetti et al., 1997) of the fucino basin, elephas antiquus falc. & cautl. and hippopotamus antiquus desmarest (middle pleistocene; gazzetti, pers. com.; petronio pers. com.) of the tirino valley. a further chronological element is represented by the presence, in the continental deposits, of abundant sedimentary material related to volcanic activity. these sediments indicate an age subsequent to the beginning (about 0.6 ma) of the most recent volcanic phase in central italy (both in the tyrrhenian sector and in the apennine area; see fornaseri, 1985; narcisi and sposato, 1989; barbieri et al., 1996 on the chronological aspects). chronological constraints can also be derived from paleomagnetic data which indicate reverse polarity for some deposits of the abruzzi apennines (d'agostino et al., 1997; messina et al., 2001), suggesting an age older than the limit bruhnes-matuyama (0.78 ma). these data are available for slope-derived breccias distributed throughout the entire latium-abruzzi apennines, for alluvial deposits of the upper aterno valley and for lacustrine sediments of the middle aterno valley. the available chronological dataset permits to constrain the age of most of the pleistocene deposits detected in the investigated area. the age of the oldest deposits, generically attributed to the pliocene in the works on the fucino plain, the salto valley and the turano valley (e.g. bertini and bosi, 1976; bosi, 1989; bosi et al., 1995), cannot be defined in detail, due to the lack of bio-stratigraphic constraints. the reasons for attributing these deposits to the pliocene are: 1) they are younger than continental sediments related to the messinian (bosi and messina, 1990; cipollari et al., 1999) which experienced the compressive deformations of the central apennines; 2) these deposits unconformably cover the miocene marine substratum (e.g. bertini and bosi, 1976); 3) sedimentary material from the lower part of the successions defines a provenance from areas not related to a physiography comparable to the present one; in particular, the abundance of clayey-sandy sediments indicates that the deposition was fed by areas entirely made of miocene flysch (bertini and bosi, 1976); in contrast, the quaternary deposition is conditioned by erosion of the carbonate bedrock in which most of the present slopes are carved; 4) the changes which affected the landscape (e.g. in terms of amount of erosion) between the first depositional event and the second one are much more significant than the changes of the landscape during the last 1 ma; 5) an erosional surface separates, in the different basins, the sediments of the first event from those related to the second (early pleistocene) depositional event (fig. 2); 6) an evident unconformity separates the sediments of the first depositional event (strongly deformed, tilted and displaced along normal faults, e.g. fig. 2) from those of the second depositional event, indicating the occurrence of significant tectonic deformations preceding the erosional surface of point 5; 7) the sediments of the first depositional event are characterised by a large thickness (more than 300 m in the salto valley and in the fucino basin) indicating the persistence of the related depositional environment for a long time interval. point 3 indicates a physiography of the first event basins very different from that of the second depositional event; points 4, 5 and 6 qualitatively indicate that a long time span separates the first two depositional events; point 7 indicates that the first depositional event may have lasted for a long period. on this basis, we hypothesise a pliocene age for the first depositional event (although it may have partly occurred during the early pleistocene). the occurrence of pliocene continental deposition in the intermontane basins of the plio-quaternary continental deposits ... 2 in the present paper, as currently proposed in quaternary geology, we consider the limit early pleistocene-middle pleistocene coinciding with the limit bruhnes-matuyama of the paleomagnetic stratigraphy (i.e. 0.78 ma). 60 latium-abruzzi apennines has also been hypothesised by other authors (e.g. cavinato, 1993; carrara et al., 1995; barberi et al., 1995; cavinato et al., 2002). the chronological attribution is generally based on considerations similar to those summarised in the previous points. tthhee llaattiiuumm--aabbrruuzzzzii aappeennnniinnee ccoonnttiinneennttaall ssttrraattiiggrraapphhiicc sscchheemmee the procedure above discussed brought to a first stratigraphic scheme at the end of the 80s (bosi, 1989) which was revised by bosi and messina (1991). in these schemes, depositional and morphological units were correlated among five different basins. the same schemes were redrawn by galadini (1999) who included information on the liri valley derived from carrara et al. (1995). other attempts to correlate continental successions in central italy have been published during the 90s (cavinato et al., 1994; cavinato and de celles, 1999). the former work tried to correlate the tectonic-sedimentary evolution of intra-appennine basins with the volcano-tectonic activity of the tyrrhenian margin. the correlation of intermontane basins (leonessa, rieti, fucino, sulmona) is made on the basis of the comparison of continental successions (for which chronological constraints are not abundant), without defining depositional/erosional histories for each of the reported basins. only the fucino basin is common to the schemes of cavinato et al. (1994) and bosi and messina (1991). cavinato and de celles (1999) is, instead, aimed at correlating geological events along a transect across central italy, thus considering the events of the tyrrhenian sector, those of the apennine chain and those of the adriatic margin during the pliocene and the quaternary. due to the non-stratigraphic aim of the paper, the authors attribute chronology to the continental successions without justifying the choices made. it is not possible, therefore, to define the reliability of the stratigraphic background. this work, however, has only the fucino and l'aquila basins in common with the bosi and messina's scheme. in the case of these basins the two stratigraphic proposals seems comparable. we updated the scheme by bosi and messina (1991), summarising the knowledge related to seven different basins (figs. 2 and 3). as indicated in the introduction, in the new scheme we defined stratigraphic and morphologic features of the basins for which the writers have had direct field experience. for this reason, the stratigraphy of the liri valley (carrara et al., 1995) is not reported in figure 3. moreover, although the stratigraphic knowledge for the rieti and sulmona basins (similar to the other investigated depressions as for the continental physiographic evolution) is very detailed (e.g. cavinato, 1993; miccadei et al., 1998a), data are not expressed through schemes similar to those of figure 2. therefore, these data cannot be used for our purposes. chronological attributions in figure 3 have to be taken with caution particularly for the age of the first depositional event above discussed. some remarks on the continental succession of this area are proposed, however, in the section dedicated to the stratigraphic data from other basins. symbols for defining lithological/sedimentological characteristics of the different units have been adopted in figure 3, together with specific symbols which permit to identify extended erosional paleosurfaces carved into the deposits and depositional top surfaces of stratigraphic units. the main differences between the old scheme and the new one are: 1) the salto and the turano valleys have been reported as two different basins, due to new fieldwork (unpublished data) made during 2001 by the authors of the present paper; 2) the tirino valley has been reported in figure 3 as the result of the work made by giuliani and sposato (1995) and further fieldwork made during 2002; 3) a third unit has been defined in the salto valley after new geological surveys made during 1999 (messina, unpublished data); 4) the stratigraphic setting of the fucino plain has been slightly changed after the fieldwork made since the beginning of the 90s (bosi et al., 1995 and further unpublished data); 5) a first depositional event has been defined in the l'aquila basin, resulting from fieldwork of the middle 90s (unpublished data); 6) a first depositional event has been tentatively defined for the middle aterno valley on the basis of geological surveys made during 2000-2001 (unpublished data); 7) new bio-chronological data have been reported (hippopotamus antiquus desmarest, elephas antiquus falc. & cautl. in the tirino valley, gazzetti, pers. com.; petronio pers. com.; equus altidens reichenau in the fucino basin, blumetti et al., 1997); 8) paleomagnetic data indicating reverse polarity of deposits, i.e. ages older than 0.78 ma have been reported (data derived from d'agostino et al., 1997 and messina et al., 2001). the most important change is, however, represented by the different location of the erosional events represented by the aquilente, mt. marine and anzano top paleolandscapes. these are extended flat and subhorizontal erosional landscapes, carved into the marine substratum. the aquilente top paleolandscape (tpl) followed, in the scheme by bosi and messina (1991), the first depositional event in the salto valley. the other two above mentioned tpls were put in the same stratigraphic position in the old scheme, although evidence for the first depositional event was lacking in the l'aquila and middle aterno basins. recent surveys in the salto valley permitted to make a different hypothesis about the relationship between the aquilente tpl and the deposits of the first depositional event (galadini et al., 2003). according to the mentioned authors, indeed, the modelling of the top paleolandscape occurred before the deposition of the first unit. this hypothesis is based 1) on the observation of coarse deposits related to the first depositional unit along the slopes roughly corresponding to the present ones and 2) on the inferred necessity of a stable base level over a large area for the formation of the aquilente tpl. point 1 defines a persistence of the salto basin slopes during time since the deposition of the first unit, i.e. a persistence of the salto depression during time. the consequence is that since the first depositional event, this area was characterised by an indented landscape. this evidence renders the hypothesis of a tpl formation subsequent to the first depositional event problematic, since the condition for a base level stable during a long time span in the tpl area (characterised, on the contrary, by unstable slopes c. bosi et al. and basin areas with lacustrine deposition), cannot be easily satisfied. similar conclusions may be drawn for the other two above mentioned tpls (mt. marine and anzano) and for this reason, following the hypothesis by galadini et al. (2003) we put the tpl remnants before the first depositional event in fig. 3. ccoonnttiinneennttaall ssttrraattiiggrraapphhyy ooff ssoommee iinntteerrmmoonnttaannee bbaassiinnss in the sections below, a short summary of the continental stratigraphy related to the basins we investigated is proposed. turano valley reference studies: melchiorri (1987); bosi (1989); galadini et al. (2003). the middle-upper turano valley was a closed basin during the first continental depositional event, as indicated by the presence of lacustrine deposits. during most of the quaternary, however, this area was drained and the old lacustrine deposits eroded. these deposits represent the lower portion of the first unit ("santa croce" in fig. 3; see also fig. 2) and are mainly made of sandy-silty deposits (fig. 4a) with sparse arenaceous and carbonate pebbles (melchiorri, 1987; bosi, 1989). the lithology of fine sediments indicates a deposition fed by the miocene clayey-arenaceous flysch extensively outcropping in the investigated area. the upper stratigraphic horizons are, instead, made of conglomerates with mainly arenaceous and secondarily carbonate pebbles (fig. 4b), alternating with sands and silts. close to the valley flanks, the presence of large boulders and blocks both arenaceous and cal61plio-quaternary continental deposits ... fig. 3 stratigraphic scheme (and morphological features related to the main erosional landscapes and top depositional surfaces) of the latium-abruzzi apennines. the available chronological constraints (bio-chronological data, volcanic deposits, paleomagnetic data) have been summarised. careous indicate instability phenomena along the basin borders during the deposition of the santa croce unit. the uppermost deposits of this unit are represented by carbonate slope-derived breccias conformably covering the mainly clayey-arenaceous deposits. these breccias define a modification of the landscape in the investigated area, since it was initially characterised by slopes mainly carved into the clayey-arenaceous flysch and subsequently (until the present) characterised by more indented slopes carved into the carbonate bedrock. the entire santa croce unit generally displays layers dipping towards n or ne (fig. 4a), i.e. the deposits are evidently tilted as a result of the activity of the nw-se normal fault bordering the depression to the ne (melchiorri, 1987; galadini et al., 2003). the thickness of the preserved deposits related to this unit can be estimated in about 200 m. the second unit ("le grotte" in fig. 3; see also fig. 2) is entirely made of carbonate slope-derived breccias, with layers dipping towards the valley, unconformably covering the older unit. the breccias are made of angular-to-sub-rounded carbonate pebbles usually in pink-orange matrix, sometimes characterised by an open-work texture. this unit is made of the typical slope-derived breccias outcropping along many slopes of the central apennines. the thickness does not exceed several tens of metres (melchiorri, 1987; galadini et al., 2003). salto valley reference studies: bertini and bosi (1976); bertini et al. (1986); mariotti and capotorti (1988); bosi et al. (1989); galadini and messina (2001); galadini et al. (2003). similarly to the previously described basin, also the middle salto valley was characterised by the presence of a lacustrine environment during the deposition of the local first unit ("piagge" in fig. 3; see also fig. 2). after the deposition of this unit, however, the basin was drained and a large part of the lacustrine deposits was eroded. presently, the salto river incides the marine substratum made of miocene flysch. the oldest geomorphic feature detected in the salto valley area is represented by the remnants of a top paleolandscape ("aquilente" in fig. 3) at 1,350÷1,450 m a.s.l. it is a flat and sub-horizontal erosional landscape which formed during a phase of stability of the base level, in a geomorphic framework completely different from the present one (galadini et al., 2003). the oldest unit outcropping in this area ("piagge" in fig. 3) defines a geological evolution similar to that of the turano valley. this unit is mainly made of fine sands and silty sands whose lithological characteristics indicates a lacustrine deposition. the pebbles of the gravel horizons are mainly arenaceous in the lower part of the succession and become more and more rich of carbonate pebbles towards the upper part. in the middle part of the succession, a several-m-thick horizon containing arenaceous boulders of tens of cubic metres (fig. 5a) was detected by bosi et al. (1989). this portion defines instability phenomena along the borders of the sedimentary basin. it is clear, indeed, that the presence of big boulders is anomalous within the lacustrine depositional environment. the thickness of the preserved deposits related to the piagge unit is larger than 300 m. outcrops of this unit have been observed between about 700 and 1000 m a.s.l. in the fiamignano area. the second unit ("canalicchio" in fig. 3; see also fig. 2) is made of a thick succession of carbonate gravels and conglomerates. sometimes, 10-m-thick layers consisting of rounded arenaceous boulders (diameter 30÷40 m) are present. the matrix in these cases has a sandy (fed from arenaceous rocks) and pebbly (carbonate pebbles) grain size. the thickness of the outcropping deposits is about 400 m (bosi et al., 1989). other horizons containing boulders have been observed in the lower part of the succession ("strati di concerviano" in bosi et al., 1989). the boulders (several cubic metres) are both arenaceous and calcareous. slope-derived breccias in the fiamignano area (fig. 5b) can also be related to the second depositional event. remnants of a flat and horizontal surface overlaying the canalicchio unit have been observed at places in the northern sector of the depression. they have been interpreted as faintly re-modelled remnants of the original depositional top surface. the third unit ("arapetrianni" in fig. 3; see also fig. 2) is entirely made of well layered gravels with 62 c. bosi et al. fig. 4 a) layered sands and silts of the first depositional units in the turano valley ("santa croce" in fig. 3); the deposits have been tilted (towards ne) as a result of the tectonic activity of the fault bordering the basin; b) sedimentological characteristics of the pebbly portion of the first depositional event (turano valley); pebbles and matrix derived from the erosion of the miocene clayey-arenaceous flysch. mainly carbonate pebbles. these deposits, outcropping in the area of the arapetrianni village, are characterised by a thickness of several tens of metres. ongoing investigations will provide more detailed stratigraphic and sedimentological information on this unit. fucino plain reference studies: beneo (1939); demangeot (1965); raffy (1970 and 1983); nijman (1971); accordi (1975); bertini and bosi (1976); zarlenga (1987); bosi and messina (1990); blumetti et al. (1993 and 1997); galadini and messina (1994); bosi et al. (1995 and 1999); messina (1996); cavinato et al. (2002). the fucino plain has been investigated by researchers of different institutions during time (fig. 6). most of the works have been made in the neotectonic perspecti63plio-quaternary continental deposits ... fig. 5 a) arenaceous blocks in sandy matrix related to the first depositonal unit of the salto valley ("piagge" in fig. 3); b) layered slope-derived breccias of the second depositional unit in the salto valley; the breccias are presently dipping into the slope as a result of tilting due to gravitational phenomena. ve, to evaluate the history of the vertical movements in sectors separated by plio-quaternary faults or to define the recent structural evolution. the large number of available studies (whose conclusions in stratigraphic terms are summarised in fig. 6) is due to the fact that the continental deposits in the fucino area outcrops much more extensively than in other central apennine intermontane basins. this is a paradox if one considers that the fucino basin is the only presently closed depression among the basins investigated in the present paper, that is the erosion of a river has not entrenched the continental deposits. indeed, the structural framework of this area, with parallel normal faults which isolate "slices" of continental deposits and suspend them over the present plain bottom, is the main cause for the "visibility" of the plio-quaternary deposits. we took stratigraphic information on the fucino basin from the works by bosi et al. (1995 and 1999), although a more recent work is available (cavinato et al., 2002). the authors of the latter work, indeed, do not 64 c. bosi et al. fig. 6 schematic representation of the available knowledge on the fucino stratigraphy according to the different works. take into account the evidence of erosional phases which are clearly recorded in the fucino landscape as remnants of extended erosional paleosurfaces carved into the continental deposits (see section dedicated to the general stratigraphic scheme for a discussion). this limits the use of the stratigraphic data in the perspective of the continental geological evolution and, in practical terms for our paper, does not permit to give a picture of the fucino stratigraphy comparable to that of the other basins. the oldest unit ("aielli" in fig. 3; see also fig. 2) outcropping in the fucino area (mainly along the northern basin border) is made of clays, silts and sands of greyish and yellowish colour (fig. 7a), mainly related to a lacustrine environment. outcrops of the basal horizons have been observed at 750 m a.s.l. in the aielli area. as in the previous cases, the lithology reveals that deposition was fed by the miocene flysch. in the middle part of the succession (900 m a.s.l.), the percentage of gravel layers increases. the gravels are mainly made of carbonate pebbles (subordinately arenaceous pebbles) in sandy matrix. the upper part of the succession is made of breccias laterally transient to gravels, sands and layered silts dipping towards nne. the breccias contain carbonate blocks with volume up to hundreds of cubic metres. the presence of million-cubic-metres blocks defines significant instability of the slopes close to the basin at the time of the first unit deposition. the uppermost portion of the succession is exposed at about 1,050 m a.s.l., north of the aielli village. the thickness of the outcropping deposits is about 400 m. the second unit ("cupoli" in fig. 3), embedded in the older one (fig. 2) is exposed between celano and aielli and along the eastern basin border. it consists of gravels intercalated with sands and, more rarely, with silty-clayey horizons. whitish silts outcropping between collarmele and pescina, unconformably covering the pliocene deposits and underlaying the pescina unit, have been attributed to the cupoli unit by bosi et al. (1995). the depositional environment is lacustrine and fluvial. the maximum thickness of the outcropping deposits is about 120 m. in the area of cupoli, a flat and sub-horizontal surface ("alto di cacchia" in fig. 3) is carved into the uppermost portion of this unit (fig. 7b). this surface probably represents a faintly modified remnant of the original depositional top surface. faults affecting the deposits related to the cupoli unit and the tilted geometry of the whitish silts along the eastern basin border define the significant tectonic activity experienced by the sediments of the second unit. when the deposition related to the second unit occurred within the basin, the "bisegna breccias" (bosi and messina, 1990) deposited along the slopes (fig. 7c). the breccias are the typical product of the slope deposition related to the second unit in all the basins discussed in the present paper. they are made of carbonate angular pebbles in pink-orange sandy-silty matrix, are well layered and usually dipping towards the basin or characterised by a sub-horizontal attitude. the main outcrops of breccias have been detected along the southern slope of the tre monti relief, the southern slope of the magnola mts. and the left flank of the 65plio-quaternary continental deposits ... fig. 7 a) alternating sands and gravels of the upper portion of the first depositional unit ("aielli" in fig. 3) in the fucino basin (photograph taken at the beginning of the 90s at the southern entry of aielli); b) panoramic view (from wnw) of the cupoli hill, entirely carved into the gravels and silts of the second depositional unit; the top of the hill (encircled by the black line) roughly correspond to the depositional top surface of the deposits; c) slope-derived breccias of the fucino second depositional unit, along the southern slope of the magnola mts. (northern border of the fucino basin); d) layered gravels of the fucino third depositional unit ("pescina-casoli-pervole" in fig. 3) along the giovenco valley (eastern border of the fucino basin); the white arrow indicates a fault affecting the gravels. celano gorge. a mature red paleosol developed over the "bisegna breccias" along the southern slope of the tre monti relief. the maturity of the paleosol and the comparison with similar soils in other parts of the apennines suggest an age of several hundreds thousand years (magaldi, pers. com.). the third unit ("pescina" in fig. 3), embedded in the second one (fig. 2), is prevalently made of carbonate gravels outcropping along the eastern basin border (fig. 7d). the sedimentological characteristics define a fluvial environment ("braided stream"). the maximum thickness of the outcropping deposits is about 50 m. a fragment of equus altidens reichenau has been found within this unit by blumetti et al. (1997) in a pedogenized reddish soil sediment. this remains permits to relate the deposits to the early-middle middle pleistocene. stratification is generally sub-horizontal or slightly dipping into the slope as a result of the tectonic tilting. the tectonic suffered by this unit (fig. 7d) is also indicated by the fault planes detected in the gravels by bosi et al. (1995). the depositional top of the pescina unit is not preserved and the layers are truncated by erosional surfaces at about 870 m a.s.l. at lower elevations, in the same area where the pescina deposits have been identified, slightly younger deposits have also been detected by bosi et al. (1995) and messina (1996), included in the pescina unit in the scheme of figure 3. these deposits have been reported as "casoli", "collarmele" and "pervole formations" in the mentioned papers. they consist of gravels and sands of fluvial origin; their depositional top surfaces are, in these cases, well preserved. the fourth unit ("boscito" in fig. 3; see also fig. 2) marks the beginning of the volcanic deposition in the fucino basin. it consists of sands rich of volcanic minerals and subordinately carbonate gravels of fluvial origin. it can be related to the middle pleistocene on the basis of the chronological data on the beginning of the most recent volcanic phase in central italy (fornaseri, 1985; narcisi and sposato, 1989; barbieri et al., in press). sangro valley reference studies: colacicchi (1967); aa.vv. (1986); galadini and messina (1990, 1993a, 1993b); galadini et al. (1998); pace et al. (2002). the oldest unit of the sangro valley outcrops along the southern margin of the pescasseroli basin ("campo rotondo" in fig. 3; see also fig. 2) between 1,200 and 1,450 m a.s.l. it is made of carbonate cobbles and boulders (fig. 8a) with dimensions up to some cubic metres and directly overlays the marine substratum. fieldwork permitted to identify few blocks with dimensions up to 40÷50 cubic metres. the thickness of the preserved deposits related to this unit is about 60÷70 m. the deposition is due to large landslide episodes related to landscapes which are no more preserved (galadini and messina, 1990). the mentioned authors also mapped some nw-se faults responsible for the displacement of the campo rotondo unit. the second unit ("pescasseroli" in fig. 3; see also fig. 2), embedded in the older one, is made of gravels and conglomerates laterally transient (towards the valley flanks) to slope-derived breccias (figs. 8b, c and d). few layers of sands and silts have been detected within the carbonate gravels. the attitude is generally subhorizontal (fig. 8d); grading is both normal and reverse (galadini and messina, 1993a). the breccias are made of carbonate angular pebbles and cobbles and are characterised by a varied degree of cementation. the calcareous sandy matrix has often a pinkish colour. layers are generally dipping towards the valley and present a sub-horizontal attitude in the area of transition to the gravels (galadini and messina, 1993a). the lithological characteristics and the stratigraphic position within the continental succession of the sangro basin permits to correlate these breccias with the second unit breccias extensively outcropping in other basins of the central apennines. the pescasseroli unit is characterised by a maximum thickness of 140÷150 m. remnants of the depositional top surface are sporadically preserved at elevations between 1,460 and 1,470 m a.s.l. the described unit is clearly affected by tectonic displacements. the most evident effect of the recent tectonic activity is represented by the 60÷120 m high fault scarp separating the colli alti and the colli bassi areas, close to pescasseroli (fig. 8b). the fault scarp is entirely carved into the gravels and conglomerates of the described unit. the third unit ("spineta" in fig. 3; see also fig. 2) is entirely made of slope-derived carbonate breccias, with angular pebbles of dimension up to 20 cm, in carbonate sandy matrix of generally whitish colour. the thickness does not exceed 10 m. since direct chronological constraints for the described units are lacking, their position in the chronological framework of figure 3 has been defined by correlating the sangro valley deposits with those of the fucino area (galadini and messina, 1993a). correlation has been based on the comparison of the quaternary geological history of the two adjacent basins. as usual, the slope-derived breccias of the early pleistocene, due to their deposition along most of the central apennine slopes, represent a fundamental unit for the definition of chronological constraints. continental deposits have also been detected in the southern part of the upper sangro valley. they mainly consists of slope-derived breccias outcropping along the southern slope of mt. greco (aa.vv., 1986; pace et al., 2002). most of the breccias mapped in aa.vv. (1986) in this area can be attributed to the second unit. on the basis of the work by pace et al. (2002) it is clear, however, that also more recent slope deposits outcrop. ongoing investigations by the authors of the present paper will define a detailed stratigraphy for this sector. l'aquila basin reference studies: demangeot (1965), bosi (1989); blumetti et al. (1996); messina et al. (2001). the oldest geomorphic feature preserved in the l'aquila basin (corresponding to the area of the upper aterno valley) is represented by the remnants of a flat and sub-horizontal tpl, at elevations between 1,400 and 1,500 m a.s.l. it is carved into the meso-cenozoic carbonate succession and the clayey-arenaceous flysch of miocene age. the major remnants of the paleolandscape are preserved in the footwall of the mt. marine fault. considering the large extension of the mt. marine tpl and therefore the evidence for its formation during a phase of stability of the regional base level (i.e. when 66 c. bosi et al. a local basin was not present), we believe that the l'aquila basin formed as the result of the mt. marine tpl displacement, according to models already published in basili et al. (1999) and galadini et al. (2003). the oldest unit ("pianola" in fig. 3; see also fig. 2) outcrops south of the l'aquila basin and is made of layered sands and silts of prevalently lacustrine origin. the mineralogical composition is represented by abundant quartzose, plagioclase and muscovite granules which indicate that the deposition of this unit was fed by the miocene flysch. the investigated outcrops showed that the deposits are intensely deformed, as indicated by the number of outcrop-scale faults and by the attitude of the layers, suggesting a tilting of 15÷20° towards north. sandy-silty deposits (intercalated with gravels) have been paleomagnetically analysed in the northernmost sector of the l'aquila basin (area of barete). the analysis defined a normal polarity (messina et al., 2001). since these sediments represent the oldest unit of the area, the mentioned authors hypothesised an age older than 1,770 ma, thus providing evidence for the presence of pliocene deposits in the upper aterno valley. the second unit ("madonna della strada-san marco" in fig. 3; see also fig. 2) can be detected between 680 and 1,010 m a.s.l. and is made of alternating silts and sands in the lower part and gravels (coarsening upward) in the upper part. the arkidiscon meridionalis vestinus azzaroli was found in the lower part of this unit (azzaroli, 1977). this unit is probably ("question mark" in fig. 3) laterally transient to slope-derived breccias which extensively outcrop along the northern portion of the mt. pettino fault ("san marco breccias", fig. 9a). this hypothesis is not based on direct field observation but on the similarity of the l'aquila basin stratigraphy with that of the other basins where the lateral transition from basinal to slope-derived breccias was observed in the field. paleomagnetic analyses sho-wed a reverse magnetic polarity for the breccias, thus indicating an age older than the bruhnes-matuyama li-mit (0.78 ma) (messina et al., 2001). similar results have been obtained from paleomagnetic analyses on the alluvial succession of the cona della croce excavation (fig. 9b), south of arischia (messina et al., 2001). these deposits have been related to the second depositional event by the mentioned authors. two different erosional surfaces (preserved as remnants in the landscape of the l'aquila basin) are carved into the deposits of the second unit. the remnants of the highest and oldest surface ("colle di sassa" in fig. 3) can be detected at 800÷900 m a.s.l., while the 67plio-quaternary continental deposits ... fig. 8 a) blocks of the first depositional unit of the upper sangro valley (campo rotondo area, pescasseroli basin); b) panoramic view (from north) of the pescasseroli basin (upper sangro valley); most of the depression is filled by gravels and conglomerates of the local second depositional unit ("pescasseroli in fig. 3); the white arrows mark the base of the scarp affecting the colli alti-colli bassi area, resulted from the activity of a fault which displaced the top depositional surface of the sediments; c) view of the conglomerates of the second depositional unit and of the landscape roughly corresponding to the top depositional surface in the colli alti area (eastern pescasseroli basin, upper sangro valley); d) detail of the sub-horizontal conglomerates of the second depositional unit in the upper sangro valley; carbonate pebbles are angular, indicating a proximity to the slope. lowest surface ("san bartolomeo" in fig. 3) is preserved at 775÷800 m a.s.l. (fig. 9c). the third unit ("civitatomassa" in fig. 3; see also fig. 2) is made of gravels related to a fluvial depositional environment. the top depositional surface of this unit is preserved at places (at 730÷740 m a.s.l.) and it may be correlated (on the basis of the altitude and of the relationship with the other, older and younger, paleosurfaces exposed in the area) with the above mentioned erosional surface of "san bartolomeo" (fig. 9c). part of the successions described by blumetti et al. (1996) for this area are related to the madonna della strada unit. they are mainly made of sands and gravels, while the colle macchione succession (about 25 m thick), mainly consists of "megabreccias" with carbonate blocks of several cubic metres overlaying sandy silts of lacustrine origin. the authors defined a debris flow origin for the "megabreccias". younger sediments have also been found in the 15-m-thick case buccella succession, made of gravels (with cut-and-fill structures) alternating with sands. the presence of abundant volcanic minerals may indicate a middle pleistocene age (on the basis of the chronology of the central italy volcanic activity). these sediments may represent a local fourth unit. the lack of conclusive data on this point, i.e. the impossibility to exclude that these deposits are significantly more recent than the beginning of the volcanic activity, presently prevent the representation in figure 3. middle aterno valley reference studies: demangeot (1965); bosi and bertini (1970); bagnaia et al. (1989); bertini et al., (1989); galadini and giuliani (1991); bertini and bosi (1993); d'agostino et al. (1994 and 1997). as in the case of the previously described basin, also in the middle aterno area remnants of an old tpl ("anzano" in fig. 3) have been detected at about 1,400÷1,500 m a.s.l. the tpl is carved into the marine carbonate substratum and is suspended of about 1,000 m over the aterno depression. since all the outcropping deposits and the related geomorphic features (both erosional and depositional top surfaces) are embedded into the tpl, the latter is the oldest geomorphic feature detectable in the investi68 c. bosi et al. fig. 9 a) panoramic view of the san marco area (l'aquila basin, upper aterno valley); outcropping rocks are made of cemented slope-derived breccias of the second depositional unit; paleomagnetic analyses indicate an age older than the limit bruhnes-matuyama (0.78 ma); b) gravels, sands and silts of alluvial origin, related to the second depositional unit, in the arischia area (excavation of cona della croce; upper aterno valley); also in this case the paleomagnetic analysis gave an age older than the limit bruhnes-matuyama (0.78 ma); c) panoramic view from scoppito towards south (l'aquila basin, upper aterno valley); the arrows indicate the remnants of the san bartolomeo surface, roughly corresponding to the depositional top of the third depositional unit. gated area (galadini et al., 2003). the oldest deposits detectable in the area of the middle aterno valley ("campana" unit in fig. 3) have been observed in the lowest sector of the tectonic depression which formed in the area between san demetrio ne' vestini and barisciano. similarly to other investigated basins, the lithology of this unit, mainly made of sands, indicates a deposition fed by the miocene flysch. about 6 km north of barisciano, in the area of mt. ruzza, slope derived breccias outcrop extensively. the cemented breccias are displaced and affected by fault scarps. the deposition occurred over the anzano tpl and the sub-horizontal attitude indicates that it affected an area with scarce relief energy. this means that the breccias deposited before the formation of the middle aterno valley depression, whose bottom is located about 1,000 m below the anzano tpl. although these breccias represent the oldest depositional episode in the area where the anzano tpl is preserved, the relationship with the sands of campana cannot be defined. similarly to other basins, the mt. ruzza breccias may represent the typical product of deposition in slope areas in a period during which the innermost portion of the basin was characterised by the deposition of the sands of campana. in the second unit ("fonte vedice-san nicandro" in fig. 3; see also fig. 2) we put different sub-units. the oldest sub-unit is represented by the san nicandro whitish silts (bosi and bertini, 1970; bertini and bosi, 1993), related to a lacustrine environment. the silts are well layered, sometimes laminated and affected by significant tectonic deformation indicated by the numerous outcrop-scale faults which can be detected in the investigated area and by the tilted geometry of the layers (fig. 10a). paleomagnetic analyses made on the san nicandro silts defined a reverse magnetic polarity (speranza pers. com.) which indicates an age older than the bruhnes-matuyama limit (0.78 ma). these silts are laterally transient to slope derived breccias made of angular to sub-angular carbonate pebbles and cobbles (fig. 10b) in carbonate sandy matrix ("valle valiano formation" in bertini and bosi, 1993). the breccias are well layered and usually (when not affected by tectonics) dip towards the aterno basin. the "fonte vedice breccias" represent a younger sub-unit made of the typical cemented carbonate breccias with orange-pink matrix widely outcropping in the entire abruzzi region (bertini et al., 1989). d'agostino et al. (1997) defined a reverse paleomagnetic polarity which suggests an age older than 0.78 ma. the breccias can be detected along the slopes bordering minor depressions between the barisciano sector of the middle aterno valley and the gran sasso chain (bertini et al., 1989). according to bertini and bosi (1993), these breccias are laterally transient to conglomerates of fluvial origin ("valle colle formation" in bertini and bosi, 1993) in the area wnw of barisciano. extended remnants of an erosional paleosurface ("petrara" in fig. 3) is carved into the deposits of the second unit (san nicandro silts, valle valiano breccias) and into the carbonate units of the marine substratum (bertini and bosi, 1993). the third unit ("valle dell'inferno" in fig. 3; see also fig. 2), embedded in the second one, is made of well-layered gravels and conglomerates intercalated with silty-sandy levels (fig. 10c). this unit sometimes covers lens-shaped levels of a reddish soil sediment, similar to that previously mentioned in the fucino basin, which gave the remains of equus altidens reichenau. its top depositional surface is preserved in many places ("valle daria" in fig. 3; fig. 10d) and is laterally transient to an erosional paleosurface carved into the marine substratum. the fourth unit of the middle aterno valley ("san mauro-san giovanni" in fig. 3; bertini and bosi, 1993), is made of carbonate gravels and sands in the lower part ("san giovanni formation" in bertini and bosi, 1993). the upper part ("san mauro formation" in bertini and bosi, 1993) is made of gravels and sands passing upward to sands intercalated with tuffite levels and layers rich of mammal bones. a peculiar aspect is represented by the abundance of tephra levels which, instead, are completely absent in all the preceding units. the youngest phase of volcanic activity in central italy began during the middle pleistocene (fornaseri, 1985; narcisi and sposato, 1989; barbieri et al., in press) and this age is usually attributed to the oldest continental deposits showing abundant tephra levels in the central apennines (see bertini and bosi, 1993 for the specific case of the middle aterno valley). this age is also consistent with the elephas antiquus italicus osborn reported in maini (1956) and found in the upper portion of the fourth unit. the depositional top surface of the fourth unit (san martino in fig. 3) is sparsely preserved throughout the investigated area. tirino valley reference studies: bosi and locardi (1991); giuliani and sposato (1995). differently from the previously mentioned basins, no evidence of deposits which may be related to the first depositional event has been found in the depressions of the tirino valley (fig. 11a). the oldest deposits of the local succession, indeed, are represented by the slopederived breccias ("villa santa lucia" in fig. 3; see also fig. 2) lithologically comparable to the second event breccias extensively outcropping in the central apennines and directly overlaying the marine substratum (fig. 11b). these breccias are made of carbonate angular pebbles in sandy matrix characterised by the typical pink-orange colour. they are layered and usually dip towards the basin (fig. 11b). outcrops of breccias have been found between 600 and 1,100 m a.s.l., sometimes with evidence of tectonic displacements (giuliani and sposato, 1995; fig. 11b). a younger unit ("convento dei cappuccini" in fig. 3), embedded in the older one (fig. 2), is made of whitish silts of lacustrine origin laterally transient (towards the basin borders) to slope-derived carbonate breccias. the silts are layered, sometimes laminated. sparse layers of sands and gravels have also been detected (giuliani and sposato, 1995). in the area of bussi officine, remains of elephas antiquus falc. & cautl. and hippopotamus antiquus desmarest have recently been found. this paleontological association define an age related to the lower part of the middle pleistocene (petronio, pers. com.). the area of these findings is very important since it represents the zone of transition from the tirino basin to the sulmona basin. according to giuliani and sposato (1995), the whitish silts observed in a borehole (made in the tirino plain) up to 150 m below the ground surface may be related to the convento dei cappuccini unit. outcrops 69plio-quaternary continental deposits ... related to these lacustrine deposits have been detected between 430 and 500 m a.s.l. slope-derived breccias have been observed at elevations usually lower than 600 m a.s.l. and are clearly embedded in those related to the villa santa lucia unit. as in the case of the older unit, also the convento dei cappuccini breccias dip towards the basin. the entire unit (breccias plus silts) has been affected by tectonic deformation (giuliani and sposato, 1995). a younger unit ("bussi" in fig. 3; see also fig. 2), embedded in the second one, is made of sands, gravels and silts of fluvial and lacustrine origin, containing a high percentage of volcanic minerals which give a greyishbrownish colour to the fine lacustrine sediments. the deposits related to this unit outcrops between 340 and 420 m a.s.l. the depositional top surface is usually well preserved and easily detectable. the bussi unit represents the first local depositional episode affected by abundant tuffite levels. for this reason it has been correlated with the tuffite succession of carapelle calvisio (giuliani and sposato, 1995), found in a closed depression near the main tirino basin by bosi and locardi (1991), ssttrraattiiggrraapphhiicc ddaattaa ffrroomm ootthheerr bbaassiinnss further works have been published at the end of the 80s or during the 90s which reported stratigraphic information on intermontane basins not discussed in the previous sections. data on the rieti basin can be derived from the works by bosi et al. (1989), cavinato et al. (1989), cavinato (1993), barberi et al. (1995) and cavinato et al. (2000). continental deposits mapped in cavinato (1993) and barberi et al. (1995), mainly consisting of conglomerates and breccias, have been attributed to two main units. the oldest one has been related to the upper pliocene-early pleistocene and the youngest to the early pleistocene. the age of the second unit has been defined on the basis of remains of equus stenonis cocchi (cavinato et al., 1989). in the piana del cavaliere area, deposits characterised by predominant material of volcanic origin with thickness of several metres have been detected (barbieri et al., 1996 and in press). radiometric analyses (40ar/39ar) made by the mentioned authors gave an age of 0.531 ma. although this age is consistent with the chronology of the volcanic activity in the tyrrhenian area, the sr isotope ratios suggest that the deposit originated from local volcanic activity. the nature of the deposits indicates that this activity is related to a surge volcanism. these data increase the importance of the intra-apennine volcanic activity, already documented in the work by bosi and locardi (1991) for the tirino basin. information on the continental deposits in the liri valley can be found in devoto (1965 and 1967) and carrara et al. (1995). the latter authors divided the suc70 fig. 10 a) carbonate silts of lacustrine origin related to the second depositional unit of the middle aterno valley; the silts have been tectonically tilted and are affected by a fault passing close to the head of the geologist (photograph taken at san pio delle camere, in a temporary excavation); b) view of the "valle valiano breccias", second depositional unit, along the road between barisciano and santo stefano di sessanio (middle aterno valley); note the huge block exposed in the central part of the photograph; c) gravels of the third depositional unit of the middle aterno valley, underlaying the surface of valle daria; note the unconformity marking the separation between two different sub-units; d) panoramic view of the valle daria surface, representing the depositional top of the third unit of the middle aterno valley. c. bosi et al. cession in different units and defined chronological constraints. therefore, in the mentioned work, pliocene, plio-pleistocene, early pleistocene, middle pleistocene and late pleistocene-holocene deposits are described. the pliocene deposits are represented by the "breccias of the 1st depositional phase", mainly made of carbonate angular pebbles and related to depositional environments completely different from the quaternary ones. the authors included the "santopadre formation" in the deposits of plio-pleistocene age. the lower part of this "formation" is made of sandy-silty horizons alternating with clayey-silty levels rich of organic matter of fluvial, lacustrine and marshy environments. an erosion surface separates this portion from the upper part of the succession made of conglomerates with mainly carbonate pebbles, without sedimentary material of volcanic origin. the thickness of the outcropping deposits is several hundreds metres. the "breccias of the 2nd depositional phase" have been included in the early pleistocene deposits. they are made of carbonate angular pebbles and at places are laterally transient to conglomerates. the breccias experienced quaternary tectonic activity, as indicated by the numerous fault planes detected in the investigated outcrops. the same chronology has been attributed to the "veroli alluvial fan" and to the "breccias of the 3rd depositional phase" which can be observed among the deposits of old alluvial fans displaced by the local fault bordering the val roveto depression. products of the volcanic activity have never been observed in the "breccias of the 3rd phase" to which a pre-middle pleistocene age has been attributed by carrara et al. (1995). the "breccias of the 4th depositional phase" represent the youngest deposits without minerals of volcanic origin and have been related to the middle pleistocene. the first deposits characterised by the presence of tephra levels have been reported as "fluviolacustrine complex of the sora basin and lirino lake" by carrara et al. (1995). these deposits consist of gravels and sands of fluvial origin and clayey silts and sands of lacustrine environment. volcanic levels have been dated at 0.58÷0.35 ma by the mentioned authors. further middle pleistocene deposits (embedded in those previously reported) have been described for this area by carrara et al. (1995). however, since their age is younger than that of the 4th unit deposits described in the previous sections, the description is beyond the scope 71 fig. 11 a) panoramic view of the depressions in the tirino valley area; the carapelle, chiancarelli and upper tirino valley basins are separated by low carbonate hills elongated in a n-s direction; b) slope-derived breccias (more than 20 m thick) related to the second depositional event, outcropping along the northern border of the carapelle depression; the white arrows indicate a fault affecting the breccias. plio-quaternary continental deposits ... of the present paper. data on the stratigraphy of the subequana basin have been published by miccadei et al. (1997). the authors identified the typical breccias we related to the upper early pleistocene and more recent deposits both of lacustrine and fluvial origin. these younger deposits are characterised by the presence of centimetric volcanic levels and therefore they have been attributed to the middle pleistocene. other alluvial fan deposits and paleosols have been related to the late pleistocene or to the upper middle pleistocene. a number of papers have been dedicated to the sulmona basin (miccadei et al., 1992 and 1998a; sylos labini et al., 1993; vittori et al., 1995; cavinato and miccadei, 1995 and 2000; ciccacci et al., 1999). these works define a continental succession which begins with breccias related to the early pleistocene. the deposits may be correlated with the slope-derived breccias of the second unit reported in the previous sections, based on their facies and stratigraphic position. middle pleistocene deposits are related to fluvial and lacustrine environments, the latter being indicated by typical whitish silts. as in the other areas, sediments containing abundant volcanic minerals or tephra levels have been observed in the sulmona plain. these sediments have been related to post-0.6 ma deposition. preliminary works are available for the continental stratigraphy of the sagittario valley and the cinquemiglia plain area. as for the former, deposition began during the early pleistocene with slope-derived breccias (barberi et al., 2001). our recent surveys in this area permitted to identify slope-derived breccias laterally (towards lower elevation) transient to conglomerates. these deposits may be related to the early pleistocene. moreover, our data indicate that an older unit is present in the area and made of breccias which deposited in an environment completely different from the present one (and not related to the mentioned conglomerates), in the serra di ziomas area. in the case of the cinquemiglia plain area, miccadei et al. (2001) defined a continental succession whose deposition occurred since the lower middle pleistocene. the oldest deposits are represented by the slope-derived breccias which deposited along the sw slope of mt. pizzalto (already mapped by miccadei et al., 1998b and attributed to the middle-late pleistocene). however, our preliminary surveys permit to relate these breccias to the typical slope deposits of the second depositional event (e.g. the fonte vedice breccias of the middle aterno valley), based on the facies and the stratigraphic position. if this hypothesis is confirmed, the age of the breccias would be slightly older than that proposed by miccadei et al. (2001). the continental deposits of the amatrice basin have been entirely related to the quaternary (cacciuni et al., 1995). the mentioned authors identified alluvial fan deposits, landslides and pediments and defined eight units. the oldest unit (sommati-amatrice) detected outcrops between 960 and 1,100 m and mainly consists of alluvial fan laterally transient to fluvial deposits and accumulations of paleolandslides. although the authors does not report explicitly the age of the unit, they relate the beginning of the deposition in the amatrice area to the early-middle pleistocene. this age can be, therefore, attributed to the sommati-amatrice unit. ccoonncclluuddiinngg rreemmaarrkkss in the previous sections we summarised the available data on the pliocene-middle pleistocene continental stratigraphy. the general scheme we propose has been drawn on the basis of the "correlation procedure" above described. the general view of the continental stratigraphy of the latium-abruzzi apennines, although the knowledge is far from being complete, permits to point out some aspects which have significant implications in the paleoenvironmental and neotectonic perspective. these aspects will be briefly summarised in the points below. 1) in almost all the basins, where the first depositional event has been identified, the lower part of the successions is characterised by sediments fed from the clayey-arenaceous flysch (turano, salto, fucino, l'aquila). this means that, at least in these basins, when the continental evolution began, the landscape was extensively carved into these marine units, differently from the quaternary landscape which was carved into the carbonate substratum. 2) in most of the basins where the first depositional event has been defined, very coarse deposits have been detected. these deposits are generally related to huge landslide phenomena within the lacustrine basins and define instability of the slopes bordering them. these sedimentary episodes i) mark the progressive indentation of the landscape as a result of the regional uplift and ii) indicate that slopes bordering basins with significant amplitude of relief where already present in the central apennines during the first depositional event. 3) all the investigated basins present on their borders the typical slope-derived breccias of the second depositional event which can be related to a period preceding 0.78 ma (based on paleomagnetic data). the ubiquitous presence of these breccias is probably related to climatic factors which conditioned the widespread deposition. since chronological data continuously corroborates the previous chronological hypotheses, the breccias may be considered as a stratigraphic marker of regional importance for the definition of paleoevent chronologies or the evaluation of tectonic rates. 4) the correlation between deposits and landforms related to the third event of the proposed stratigraphic scheme seems convincing due to the peculiar geomorphologic features which characterize this event. indeed, the deposits are bounded upward by an important flat landform partly representing the depositional top of the units, in the l'aquila, middle aterno valley and fucino basins. the surface overlays a typical reddish soil sediment in the latter two mentioned basins. 5) a further important stratigraphic marker is represented by the units recording the beginning of the volcanic activity. the investigations of the last ten years corroborate the previous hypotheses of middle pleistocene age for the first sediments containing volcanic minerals or tephra levels. generally speaking, the proposed correlations give the impression of the comparability of the depositional events in the different basins. this comparability may be interpreted as the effect of diachronous basin evolutions, each evolution passing through characteri72 c. bosi et al. stic steps which are the same for the different basins. this hypothesis would strongly contradict the possibility to correlate the depositional events across different basins on a chronological basis. it is evident, however, that an evolution of this kind cannot justify the evident comparability (across the different basins) of the succession of events (depositional, erosional) discussed in the previous pages. the comparability of successions of events (their number, the paleoenvironmental aspects, etc..) necessarily defines their sinchroneity, since it implies that the events are due to ubiquitous geomorphic agents. on this basis, we consider the proposed stratigraphic scheme as a reliable starting point for chronologically constrained neotectonic evaluations. the data summarised in the scheme proposed above and the available knowledge from the other basins not investigated by the authors of the present note indicate the lack of deposits related to the first depositional event in the easternmost depressions (e.g. tirino valley, sulmona plain, amatrice basin). this may suggest a more recent nucleation of the extensional basins towards east. although the lack of outcropping deposits related to the first event cannot exclude that the deposits are buried within the basins, the significant extension of the area where these deposits cannot be detected corroborates the younger age of formation of the eastern basins. this evidence fosters the already published hypotheses on the eastward migration of the extensional tectonics during the quaternary which were not based, however, on a detailed view of the continental stratigraphy (e.g. lavecchia et al., 1994; cavinato and de celles, 1999; galadini et al., 2001). uncertainties can affect the proposed stratigraphic scheme as for the correlation of parts of the succession related to the transition from the second to the third unit. we cannot exclude, in this case, the existence of minor depositional events different from those represented in our stratigraphic scheme. similar uncertainties may affect the upper part of the fourth unit. the main unsolved issue is the age of the first depositional event, since available chronological constraints are vague. our conjecturing indicates a long time interval between this event and the second one, but cannot quantify the length of the time span. on this basis, although a deposition mainly related to the pliocene is probable, we cannot exclude that part of the sediments are related to the early pleistocene. the individuation of the method which may cast light on this fundamental issue is presently not easy. indeed, the future discovery of paleontological findings is improbable, since nothing has been found until now, although the thickness of the outcropping deposits is several hundred metres and a large number of outcrops have been investigated in the last thirty years. we believe, therefore, that only the investigations on the relationship between dated marine deposits on the tyrrhenian margin and intra-apennine continental deposits (in the few places where a lateral transition can be detected) will produce reliable data to precisely define the age of the first depositional event. aacckknnoowwlleeddggeemmeennttss this work has been partially financed by the program cnr agenzia 2000 "strutture attive nel sistema orogenico appenninico: caratterizzazione geomorfologica, geologico-strutturale, sismogenetica e geodetica". the remains of hippopotamus antiquus desmarest have been investigated by c. petronio, r. sardella, e. dicanzio (university of rome "la sapienza"), c. gazzetti (tecnostudi ambiente s.r.l., rome) and by the authors of the present paper. the work has benefited from the discussion which, during the 90s, has involved the authors and numerous quaternary geologists and geomorphologists. for this reason we are particularly grateful to c. bartolini (university of firenze), f. carraro (university of torino), a. cinque (university of napoli) and f. dramis (university of roma tre). the authors' opinion about the morpho-stratigraphic issue may not 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(eds.), "perspectives in paleoseismology". ass. of eng. geologists, spec. publ. no. 66, 83-100. working group cpti, 1999 catalogo parametrico dei terremoti italiani. ing, gndt, sga ssn, bologna, 92 pp. zarlenga f., 1987. i depositi continentali del bacino del fucino (l'aquila, italia centrale). geol. rom. 2266, 223-253. 76 c. bosi et al. imp. aucelli & ll’’eevvoolluuzziioonnee rreecceennttee ddeellllaa ccoossttaa mmoolliissaannaa ((iittaalliiaa mmeerriiddiioonnaallee)) ppiieettrroo ppaattrriizziioo cciirroo aauucceellllii11,, ppaaoollaa iissaabbeellllaa ffaaiillllaaccee11,, ppaaoolloo ppeelllleeggrriinnoo22,, ccaarrmmeenn mmaarriiaa rroosssskkooppff11 && nniiccoollaa ssccaappiillllaattii22 1 dipartimento di scienze e tecnologie per l’ambiente e il territorio, università degli studi del molise, isernia 2assessorato ai lavori pubblici regione molise, campobasso riassunto: aucelli p. et al., l’evoluzione recente della costa molisana (italia meridionale). (it issn 0394 – 3356, 2004). nell’ambito del presente lavoro è stato effettuato uno studio dell’evoluzione geomorfologica recente del litorale molisano e, in particolare, delle variazioni più recenti della linea di costa, ricostruite con l’ausilio di un gis ed analizzate per tratti costieri e periodi distinti (1869-1907, 1907-1954, 1954-1992, 1992-1998). in particolare, si è proceduto ad una determinazione delle variazioni sia lineari della linea di riva che areali, cioè relative alle superfici di spiaggia. in base alle ricostruzioni effettuate, l’evoluzione più recente del litorale si articola in due fasi principali. una prima fase di dominante progradazione che termina all’inizio del 1900, e che trova la sua principale espressione nella costruzione degli apparati deltizi dei corsi d’acqua principali (fiumi trigno e biferno), e una seconda fase in cui si assiste ad una progressiva erosione dei delta. tale erosione, inizialmente bilanciata dalla progradazione dei tratti di costa immediatamente adiacenti alle foci, è seguita da una tendenza prevalente all’arretramento della linea di costa che persiste ancora oggi. circa le cause di tali modificazioni, l’esame dei fattori meteo-climatici, degli interventi sui sistemi fluviali e delle variazioni dell’uso del suolo suggeriscono la sovrapposizione tra fattori di controllo climatico e fattori antropici. quest’ultimi, in particolare, sembrano rafforzare i primi fino a sostituirsi ad essi in termini di importanza. per quanto riguarda le attuali dinamiche e tendenze evolutive del sistema costiero, emerge l’importanza di approfondire le relazioni esistenti tra fattori meteo-marini e dinamica costiera, e tra quest’ultima e la messa in opera di strutture protettive, al fine di definire al meglio ogni futuro intervento e migliorare le condizioni di salvaguardia. abstract: aucelli et al., the recent evolution of molise coast (southern italy). (it issn 0394 – 3356, 2004). this study deals with the recent geomorphological evolution of the sector of the adriatic coast referring to the molise region. the analysis was based on the examination of topographic sheets and aerial photographs referring to the period 1869-1998 and on field surveys to verify and integrate geomorphological data, and to analyse present trends and coastal dynamics. taking into account morphological and related hydrological features, the coast was subdivided into three sectors (from north to south sectors a, b and c). the collected data were analysed and compared by using a gis (software arc view) to obtain quantitative results about the changes of the shoreline and the beach surface which affected the three distinguished sectors during different periods (1869-1907, 1907-1954, 1954-1992 and 1992-1998). for the first period, with reference to data obtained for the sector including the biferno river mouth (sector c), a substantial stability of the delta and positive beach variations can be evidenced. within the second period, an inversion of tendency occurred and the erosion of the main fluvial deltas (the trigno delta in sector a and the biferno delta in sector c) started. the river mouths erosion was accompanied by the progradation of the adjacent coast sectors giving rise to a general positive beach surface variation. during the following periods (1954-1992 and 1992-1998), the shoreline retreat largely persisted affecting sectors a and c, while sector b was characterised by a slight progradation. on the basis of discussed data, two main evolutive phases can be reconstructed. the first one is characterised by prevailing progradation which lasted at least to 1907 and is evidenced in the study area by the construction of the trigno and biferno delta’s. the second phase is controlled by progressive beach erosion, at present still active. the phase of prevailing progradation can be related most probably to the last cold fluctuations of the little ice age, although man induced changes of land-use may have played an important role by favouring soil erosion and sediment production. conversely, the following phase of erosion can be mostly related to the progressive amelioration of climatic conditions after the little ice age and to the relative hydrological changes, combined with land-use changes essentially related to land-abandonment and, in the last decades, to the interventions on the fluvial systems as gravel mining, channel management and daming. parole chiave: evoluzione geomorfologica recente, variazioni della linea di costa, analisi gis, molise, italia meridionale. keywords: recent geomorphological evolution, shoreline changes, gis analyses, molise, south italy. il quaternario italian journal of quaternary sciences 1177(1), 2004, 21-31 11.. pprreemmeessssaa gli ambienti costieri sono soggetti ad un delicato equilibrio che dipende in crescente modo dall’azione esercitata dall’uomo. ad un progressivo degrado delle aree costiere, oltre alla loro crescente antropizzazione, sembrano maggiormente contribuire interventi sempre più numerosi sia diretti che indiretti sui sistemi fluviali, tali da rendere di difficile valutazione le possibili influenze climatiche e meteo-marine. secondo stime recenti (aminti & pranzini, 1993), circa il 63% delle spiagge italiane, tra naturali e protette, può considerarsi in equilibrio, il 32% risulta in erosione e solo il 5% è caratterizzato da una tendenza all’avanzamento. ai fenomeni di erosione costiera, che assumono una sempre maggiore importanza anche nell’area molisana, l’uomo tenta di porre rimedio attraverso la costruzione di opere di difesa costiera. così, circa il 40% della costa molisana risulta attualmente dotata di strutture di protezione trasversali e/o longitudinali. tali strutture di protezione, tuttavia, non sempre si sono dimostrate sufficientemente efficienti al fine di limitare l’erosione in atto. da ciò emerge chiaramente, che la scelta delle tipologie di strutture protettive e delle relative modalità di messa in opera non possono prescindere da una visio22 p.p.c. aucelli et al. ne articolata della dinamica costiera e dei fattori che influiscono sul bilancio sedimentario, nonché della tendenza evolutiva del settore costiero in esame. acquisire informazioni in tal senso rappresenta, dunque, il presupposto per la salvaguardia delle aree costiere. in tale ottica è stato avviato uno studio sulla evoluzione recente, la tendenza evolutiva e la dinamica attuale del litorale molisano di cui la presente nota riassume i primi risultati. 22.. iinnqquuaaddrraammeennttoo ggeeooggrraaffiiccoo ee aapppprroocccciioo mmeettooddoollooggiiccoo il litorale molisano si estende per una lunghezza di circa 35 km tra lo sbocco sul mare del formale del molino (posto circa 1,5 km a nord della foce del fiume trigno) e la foce del torrente saccione (fig. 1). orientato in direzione ca. nw-se, è costituito in prevalenza da costa bassa, comprendente piccole pianure alluvionali costiere e cordoni dunari con antistanti spiagge, e da brevi tratti di costa alta, localizzati in corrispondenza del promontorio di termoli e lungo il versante di petacciato ed intagliati su terreni d’età plio-pleistocenica. i bacini idrografici dei corsi d’acqua che sfociano lungo il litorale molisano (fiumi trigno, biferno e saccione, e corsi d’acqua minori a loro interposti) sono impostati in prevalenza su terreni arenaceo-marnosi e pelitico-argillosi, con affioramenti limitati di terreni calcarei, più estesi soltanto nel bacino del fiume trigno. complessivamente, tali terreni godono di un’elevata erodibilità, come conferma anche la diffusa presenza di fenomeni franosi e di erosione idrica accelerata. ciò si traduce in apporti alle foci prevalentemente pelitico-sabbiosi. le spiagge presenti lungo il litorale molisano, di conseguenza, sono a granulometria prevalentemente fine. procedendo da nw verso se, si rinvengono (fig. 1) le spiagge di costa verde, di marinelle, di marina di petacciato, di foce dell'angelo, di sant'antonio, di rio vivo, di campomarino, di marinelle nuove, di nuova cliternia e di ramitelli. si tratta di spiagge generalmente sabbiose, larghe alcune decine di metri, con delle dune sabbiose alle spalle. nel tratto intorno alla foce del fiume trigno (compreso tra le spiagge di costa verde e di marinelle) l’arenile è prevalentemente ghiaioso. il fondale marino posto tra la battigia e l’isobata di 5 m è caratterizzato dalla presenza di barre e cordoni sottomarini in serie, e da pendenze comprese tra 0,5 e 1,2% (zunica & girardi, 1984). un recente rilievo batimetrico del tratto di costa che dal porto di termoli si estende poco oltre la foce del biferno (assessorato ai lavori pubblici della regione molise, 2001), indica pendenze locali anche superiori al 2%. partendo da un esame preliminare della morfologia costiera e tenendo conto dell’importanza che gli apporti fluviali assumono nel bilancio costiero, la costa in esame è stata suddivisa in tre tratti (fig. 1). il primo e il terzo comprendono rispettivamente le foci dei fiumi trigno e biferno, il secondo tratto, interposto ai precedenti, risulta privo di importanti foci fluviali. l’esame geomorfologico della costa e le relative analisi quantitative sono state compiute sulla base di carte topografiche, foto aeree e ortofotocarte piane che fig. 1 – ubicazione dell’area di studio. location map of the study area. hanno consentito delle analisi comparative per gli ultimi 130 anni circa. in particolare, si è fatto uso di carte topografiche rispettivamente in scala 1:50.000 (edizioni dell’i.g.m.i. del 1869/1875 e relativi aggiornamenti del 1907/1909), 1:25.000 (i.g.m.i., 1954) e 1:5.000 (carta tecnica regionale del molise, 1992), di foto aeree in scala 1:33.000 (i.g.m.i, 1954/55) e 1:13.000 (r.t.a., 1992), nonché di ortofotocarte in scala 1:10.000 (a.i.m.a., 1998). sono state esaminate inoltre alcune carte storiche come ad esempio l’atlante geografico del regno di napoli (rizzi-zannoni, 1808) che, pur fornendo indicazioni interessanti, ovviamente non sono risultate di sufficiente precisione e dettaglio per essere utilizzate nell’analisi comparativa quantitativa. 33.. eevvoolluuzziioonnee rreecceennttee ddeellllaa ccoossttaa mmoolliissaannaa 33..11.. aannaalliissii ggeeoommoorrffoollooggiiccaa l’analisi geomorfologica è consistita in dettagliati esami cartografici ed aerogeologici, integrati da sopralluoghi lungo la costa finalizzati alla verifica ed integrazione dei dati acquisiti, e all’analisi dei tratti costieri distinti riguardo alla loro tendenza evolutiva e dinamica attuale. il tratto a il tratto a, della lunghezza di ca. 6,50 km, è compreso tra lo sbocco a mare del formale del molino (limite regionale tra abruzzo e molise) e quello del torrente tecchio (fig. 1). questo tratto è caratterizzato da una costa bassa e una fascia litorale con quote massime intorno ai 4-5 m s.l.m. dall’esame dell’atlante geografico del regno di napoli (rizzi-zannoni, 1808) e della cartografia storica dell’i.g.m.i. (1875/1907) si evince la presenza di un delta a cuspide in corrispondenza della foce del fiume trigno, caratterizzato da tre canali distributori principali, disposti a ventaglio. il tratto terminale del trigno mostra una morfologia a canali intrecciati con barre attive prive di vegetazione, interrotta da un breve tratto ad ampia sinuosità precedente la foce. a testimonianza dello stadio “giovane” dell’apparato deltizio si evidenzia una fascia a vegetazione palustre interposta tra l’odierna strada litorale e i sedimenti sabbiosi formanti gli apici del delta e i cordoni lateralmente a contatto. la netta deviazione verso nw dei tratti terminali di alcuni torrenti che sfociano in sinistra del trigno (ad es. lo stesso formale del molino) sembra indicare una direzione dominante della deriva litorale dei sedimenti (longshore drift) da se verso nw. confrontando la carta topografica del 1875 con quella del 1907 non si evidenziano variazioni nella conformazione del tratto costiero. per il periodo 1907-1954, il confronto delle relative carte topografiche evidenza una significativa erosione dell’apparato deltizio del trigno, accompagnata da una ridistribuzione dei sedimenti e una progradazione dei tratti di costa adiacenti la foce. nel 1954 non resta che un debole accenno all’originaria forma a cuspide del delta. la fascia costiera intorno alla foce risulta intensamente coltivata e si evidenzia solo qualche debole traccia dei vecchi canali distributori (in particolare del canale destro). la foce si trova spostata verso nw di ca. 500 m, indicando la dominanza di un longshore drift sempre 23l’evoluzione recente ... da se verso nw. a testimoniare la tendenza all’arretramento della linea di riva all’epoca già in atto, il tratto di costa in sinistra idrografica del trigno, e quello in sua destra compreso tra le foci del fosso mergola e del torrente tecchio (fig. 1), si mostrano interessati da vistosi processi di insabbiamento legati all’erosione della spiaggia e allo spostamento verso l’interno della fascia dunare. l’insabbiamento, che in destra del trigno si spinge localmente fino alla ss n.16 adriatica, interessa una fascia di litorale caratterizzata dalla presenza di parcelle di terreno ad assetto regolare, probabilmente adibite ad uso balneare. in destra del trigno, per ca. 1,5 km, la spiaggia appare completamente erosa e caratterizzata da una microfalesia. la linea di riva così individuata tronca nettamente e in senso obliquo i cordoni caratterizzanti il fianco destro dell’apparato deltizio. nel periodo dal 1954 al 1992 si registra un significativo arretramento della costa che interessa tutto il tratto in modo più o meno uniforme, ad eccezione della porzione posta tra le foci del mergola e del tecchio dove avviene addirittura un moderato avanzamento. non emergono, per quanto deducibile dalle fonti bibliografiche esaminate (giorgi et al., 1984; zunica & girardi, 1984), inversioni di tendenza. le stesse fonti confermano per i periodi 1954-1975 e 1975-1980 la variazione negativa della linea di riva in questo tratto e un verso del trasporto solido lungo riva da se verso nw. le poche opere di difesa realizzate tra il 1954 e 1992 sono costituite da pennelli ortogonali a protezione delle foci del formale del molino e del trigno, e dalle strutture longitudinali aderenti in corrispondenza dell’idrovora di montenero di bisaccia. dal 1992 al 1998 si verifica un ulteriore arretramento sia in sinistra della foce del trigno che in sua destra, tra la stessa foce e l’idrovora di montenero di bisaccia. risulta, invece, ancora in leggero avanzamento il tratto tra le foci del mergola e del tecchio. in questo periodo, a protezione della spiaggia di costa verde oramai quasi del tutto erosa e delle associate strutture turistiche, vengono realizzate, anche a sostituzione di quelle preesistenti, delle scogliere emerse e sommerse distaccate, disposte parallelamente o con andamento obliquo alla costa attuale lungo tutto il tratto di costa in sinistra della foce del trigno. il tratto b il tratto b si estende per circa 13 km a partire dalla foce del torrente tecchio fino alla punta del promontorio di termoli (fig. 1). in questo tratto, a parte la piccola pianura alluvionale del torrente sinarca e le spiagge di marina di petacciato, di foce dell’angelo e di sant’antonio, la fascia litorale si riduce ad un sottile nastro di spiaggia che borda i rilievi collinari di petacciato e il promontorio di termoli. mentre i primi sono impostati su un substrato essenzialmente argilloso (argille grigio-azzurre plio-pleistoceniche) interessato da diffusi e complessi fenomeni franosi, il promontorio, con una morfologia tipica da costa alta terrazzata, è caratterizzato da terreni sabbioso-conglomeratici di ambiente continentale e marino (alluvioni terrazzate di iii ordine, conglomerati di campomarino e sabbie di serracapriola del foglio 155 della carta geologica d’italia). analizzando le cartografie storiche (1869/1907), quelle del 1954 e 1992 e le ortofotocarte del 1998, 24 emerge un modesta tendenza alla progradazione di questo tratto costiero, con alcuni settori in leggero arretramento e altri in avanzamento. dati confrontabili vengono forniti da giorgi et al. (1984) che indicano non solo un comportamento diverso da settore a settore, ma anche delle inversioni di tendenza in determinati settori. così ad esempio il litorale nord di termoli risulta in avanzamento nel periodo 1954-1975 e in arretramento nel periodo 1975-1980. per quest’ultimo periodo si evidenzia un orientamento della deriva litorale prevalente da w verso e (parea, 1978; zunica & girardi, 1984). considerando il periodo 1954-1998, l’avanzamento della linea di costa più significativo si registra nell’area di marina di petacciato. ad eccezione delle scogliere longitudinali aderenti poste immediatamente in destra della foce del tecchio, oggi non più rilevabili, le opere di difesa costiera presenti in questo tratto risalgono all’ultimo ventennio. queste consistono soprattutto in scogliere longitudinali distaccate presenti lungo tutto il tratto di costa tra gli sbocchi del tecchio e del fosso del lupo e, più diradate, lungo il litorale nord di termoli e lo stesso promontorio. a queste si aggiungono una serie di pennelli ortogonali ubicati in corrispondenza dello sbocco del fosso colle degli ulivi (posto a distanza circa uguale tra le foci del torrente tecchio e del fosso del lupo) e lungo il litorale nord di termoli, che sono stati realizzati rispettivamente prima del 1992, e tra il 1992 e 1998. dopo il 1998 vengono eseguiti ulteriori interventi con la realizzazione di scogliere longitudinali distaccate nel tratto tra le foci del fosso del lupo e del torrente sinarca. il tratto c il terzo tratto si estende tra il porto di termoli e la foce del torrente saccione per una lunghezza di ca. 15,5 km. esso è caratterizzato, ad eccezione di un primo settore a costa alta posto tra il porto di termoli e la p.ta di pizzo, da una costa bassa e una piana costiera delimitata verso l’interno da rilievi collinari debolmente degradanti verso mare con locali raccordi morfologici a più alta pendenza. l’esame dell’atlante geografico del regno di napoli (rizzi-zannoni, 1808) e della carta topografica i.g.m.i. del 1869 mette in evidenza una prima fase di variazione positiva della linea di costa, marcata dalla costruzione di un apparato deltizio in corrispondenza della foce del biferno. si tratta di un delta a cuspide piuttosto prominente caratterizzato dalla presenza di depressioni occupate da piccoli stagni costieri come ad esempio il pantanello segnato in sinistra della foce. il confronto delle edizioni del 1869 e del 1907 della carta topografica i.g.m.i. mette in evidenza alcuni interessanti aggiornamenti. in particolare, questo confronto mostra, a parte i cambiamenti morfologici della porzione centrale del delta del biferno, l’avanzamento significativo del tratto di costa tra la foce del biferno e lo sbocco del collettore principale bonifica di ramitelli, con valori massimi in corrispondenza del lido di campomarino. ciò sembra indicare, peraltro, una direzione di trasporto litoraneo lungo costa prevalente da nw verso se. in sinistra della foce, i pantani risultano sostituiti da ampie aree a vegetazione paludosa. tra il 1907 e il 1954 avviene un significativo arretramento del delta che comporta una troncatura in senso obliquo delle barre sabbiose, mentre si registra un ulteriore modesto avanzamento della linea di costa in sua destra, in corrispondenza della spiaggia di marinelle nuove. nel 1954, la foce del biferno risulta molto meno prominente e ridotta ad una morfologia leggermente arcuata con bocca orientata verso n, ed i pantani in sua destra trasformati in aree paludose. a testimonianza della tendenza all’arretramento in atto, si hanno sia in sinistra che in destra idrografica della foce ampi tratti di costa soggetti ad insabbiamento. l’insabbiamento interessa una fascia di terreno larga fino a 125 m, caratterizzata da un assetto parcellare dovuto presumibilmente al suo uso balneare. durante il periodo 1954-1992, oltre ad assistere ai fenomeni di arretramento più cospicui, si verifica una maggiore diversificazione del tratto costiero in relazione alle dominanti tendenze evolutive. tale diversificazione emerge chiaramente sia dall’analisi cartografica che dall’esame dei dati raccolti da giorgi et al. (1984) e da zunica & girardi (1984). i primi, in particolare, evidenziano, per il periodo 1954-1975, il settore in sinistra del biferno in avanzamento, e quello in destra a settori alterni in avanzamento e in arretramento. osservazioni relative al periodo 1975-1980 mostrano alcune inversioni di tendenza, interessanti ad esempio il tratto in sinistra della foce del biferno e quello compreso tra il collettore principale bonifica di ramitelli e la foce del torrente saccione. in relazione all’intero periodo 1954-1992, l’arretramento della linea di riva costituisce la tendenza dominante. il tratto maggiormente colpito è quello compreso tra la spiaggia di rio vivo e il collettore principale bonifica di ramitelli, a conferma di una tendenza già evidenziata da giorgi et al. (1984) per il periodo 1975-1980 e da zunica & girardi (1984), e ciò nonostante questo tratto fosse già all’epoca dotato di opere di protezione emergenti sia longitudinali (in prevalenza distaccate) che trasversali. risultano invece in avanzamento il breve tratto corrispondente al lido di campomarino, il tratto compreso tra il porto di termoli e la spiaggia di rio vivo, e quello tra il collettore principale bonifica di ramitelli e la foce del saccione ad eccezione del settore meridionale della spiaggia di nuova cliternia. tra il 1992 e 1998 si registrano ulteriori arretramenti in corrispondenza della spiaggia di rio vivo lungo le sezioni non protette, tra la foce del biferno e il lido di campomarino, dove si osserva una accentuazione dei tomboli a tergo delle scogliere longitudinali, e infine, nella porzione più settentrionale della spiaggia di nuova cliternia. i restanti settori possono considerarsi sostanzialmente in equilibrio, a parte il settore immediatamente a contatto con il molo sud del porto di termoli, caratterizzato da un ulteriore significativo avanzamento della spiaggia. a prescindere dalle opere di protezione già menzionate, da qualche pennello ortogonale in corrispondenza del porto di termoli, e dalle armature delle foci del biferno e del saccione, le restanti opere di protezione oggi insistenti su questo tratto sono state realizzate durante gli ultimi 20 anni ca. queste consistono in una doppia (localmente tripla) fila di scogliere longitudinali tra aderenti e distaccate nel settore a sud del porto di termoli a protezione della spiaggia di rio vivo (fig. 2), una fila di scogliere longitudinali distaccate ricoprendo un tratto di ca. 7 km tra la foce del biferno e il collettore principale bonifica di ramitelli, e una doppia fila di scop.p.c. aucelli et al. 25 gliere rispettivamente distaccate e aderenti (quest’ultime saldate alla linea di costa attraverso dei tomboli) in corrispondenza del lido di campomarino. e’ stato realizzato, infine, il rafforzamento delle strutture protettive del porto di termoli con la costruzione dell’avamporto e la fortificazione del molo sud. circa le interferenze tra tali strutture di protezione e le evidenziate tendenze evolutive, i dati finora acquisiti non restituiscono un quadro univoco. infatti, sembra logico mettere in relazione la progradazione del tratto in corrispondenza del lido di campomarino e quello posto immediatamente a sud del porto di termoli con la presenza, rispettivamente, delle scogliere e delle strutture portuali. la progradazione consistente del secondo tratto, infatti, sembra essere chiaramente favorita dalla presenza delle strutture portuali che causano fenomeni di diffrazione del moto ondoso (aucelli et al., 2004) tenendo conto che il drift avviene da nw verso se (parea, 1978; zunica & girardi, 1984). di più difficile comprensione risulta invece ad esempio il fatto che le scogliere lungo il tratto compreso tra la foce del biferno e il collettore principale bonifica di ramitelli, esistenti da oltre 20 anni e più volte rafforzate nel tempo, non sembrino aver impedito il progredire dell’erosione. e’ in questo tratto che si hanno chiare evidenze del fatto che l’erosione non interessa solamente la spiaggia emersa ma anche i fondali antistanti come mostra il recente rilievo batimetrico (assessorato ai lavori pubblici della regione molise, 2001) del tratto compreso tra il porto di termoli e la foce del biferno che mette in evidenza pendenze superiori al 2% nelle sezioni interposte tra le opere protettive. 33..22 aannaalliissii qquuaannttiittaattiivvaa al fine di poter valutare in termini quantitativi le avvenute variazioni della linea di costa e di permettere una loro migliore visualizzazione, le carte topografiche e le ortofotocarte piane sono state digitalizzate, georeferenziate e messe a confronto utilizzando i software gis arc-view e autocad map. i tratti costieri distinti sono stati separatamente analizzati per i periodi 1869-1907, 1907-1954, 1954-1992 e 1992-1998. le operazioni di calcolo effettuate hanno consentito di effettuare delle valutazioni sia in termini lineari (entità di avanzamento e arretramento della linea di costa) che areali (variazioni positive e negative delle superfici di spiaggia). fig. 3 – le foci dei fiumi biferno (a) e trigno (b). the river mouths of the biferno (a) and trigno (b) rivers. fig. 2 – esempi di difesa costiera lungo la spiaggia di rio vivo, rappresentati (a) da una barriera di massi a protezione delle abitazioni e (b) da una doppia scogliera indicata attraverso le due frecce. examples of coast protection along the rio vivo beach, represented (a) by a barrier made of boulders to protect the houses and (b) a double row of longitudinal barriers marked by the two arrows. l’evoluzione recente ... 26 le variazioni lineari l’esame della cartografia storica ha mostrato una importante fase di progradazione delle spiagge e degli apparati deltizi che sembra aver perdurato fino all’inizio del 1900. infatti, il confronto tra le carte topografiche storiche dell’i.g.m.i. che rappresentano il tratto comprendente la foce del biferno (tra quelle esaminate le uniche a mostrare un aggiornamento), evidenzia, per il periodo 1869-1907, un avanzamento significativo del fianco destro del delta con un valore massimo di ca. 750 m (19,7 m/anno) in corrispondenza del lido di campomarino, mentre nullo o trascurabile si figura l’arretramento degli apici del delta. anche se, in mancanza di fonti cartografiche adeguate, non è stato possibile verificare questa tendenza per gli altri tratti di costa, questo dato consente di affermare che, almeno in quel tratto, una tendenza all’arretramento non si manifesta prima del 1907. conseguenza dell’erosione degli apparati deltizi nel periodo 1907-1954, con valori massimi di arretramento rispettivamente di circa 500 m per il trigno e di 650 m per il biferno (10,6 e 13,8 m/anno rispettivi), è l’evoluzione delle foci verso una morfologia di tipo wavedominated (fig. 3). tale erosione è accompagnata da una chiara progradazione dei tratti di costa adiacenti (fig. 4a, 4c), a testimonianza della ridistribuzione dei sedimenti di foce ad opera di correnti lungo costa. per l’intero periodo, tale progradazione è valutabile per i tratti contigui alla foce del trigno (comprendenti le spiagge di costa verde in sinistra idrografica, e il tratto tra l’idrovora di montenero di bisaccia e la spiaggia di marina di petacciato in destra) in complessivi 250 m circa (ca. 5.3 m/anno), e in circa 400 m (ca. 8,5 m/anno) per il tratto posto in destra della foce del biferno, compreso tra il lido di campomarino e la spiaggia di nuova cliternia. per le spiagge più distanti dalle principali foci si evidenzia, per lo stesso periodo, una relativa stabilità con tratti in debole avanzamento o arretramento (fig. 4b). nel periodo successivo (1954-1992), il tratto costiero intorno alla foce del trigno (fig. 5a), compreso tra la spiaggia di costa verde e la foce del fosso mergola, subisce un arretramento valutabile in circa 150 m (ca. 4 m/anno). nel tratto successivo (fig. 5b), fino alla spiaggia di marina di petacciato, la linea di costa avanza mediamente di circa 30 m, mentre resta praticamente invariata la sua posizione lungo il litorale nord di termoli. il tratto costiero compreso tra il porto di termoli e la spiaggia di rio vivo (fig. 5c) registra un avanzamento massimo di ca. 180 m, mentre quello adiacente, esteso fino al lido di campomarino, arretra in media di 200 m (ca. 5,3 m/anno), con valori locali anche superiori ai 250 m. in sostanziale equilibrio il restante litorale, compreso tra la spiaggia di marinelle nuove e quella di ramitelli, in cui si alternano tratti in debole avanzamento ed erosione. tra il 1992 e 1998, sia in sinistra che in destra idrografica della foce del trigno (fig. 6a), si registra ancora un valore medio di arretramento piuttosto elevato di 45-50 m (ca. 8 m/anno). risulta invece stabile la foce, probabilmente grazie alla costruzione di pennelli ai suoi lati. variazioni significative si rilevano ancora per la foce del biferno (fig. 6c) che risulta arretrata di circa 120 m (20 m/anno). le variazioni areali ad integrazione dei dati circa le variazioni lineari è stata compiuta un’analisi delle variazioni positive e negative della superficie di spiaggia nei vari periodi e tratti distinti i cui risultati sono stati sintetizzati nella tabella 1. limitatamente al tratto comprendente la foce del biferno è possibile mettere in evidenza per il periodo 1869-1907 una variazione positiva molto consistente di complessivi 1,7 km2 ca. (1.692.500 m2). questa variaziofig. 4 – variazioni della linea di riva e dei principali canali fluviali nel periodo 1907-1954. tratti costieri che hanno subito 1) marcato arretramento, 2) leggero arretramento, 3) marcata progradazione, 4) leggera progradazione. changes of shoreline and main fluvial channels from 1907 to 1954. coast sectors affected by 1) marked retreat, 2) slight retreat, 3) marked progradation, 4) slight progradation. p.p.c. aucelli et al. ne positiva è in gran parte imputabile all’aumento della spiaggia nel tratto compreso tra la foce del biferno e il collettore principale bonifica di ramitelli, valutabile in ca. 1.655.000 m2. l’analisi delle variazioni per periodi distinti mette in evidenza per il periodo 1907-1954 un sostanziale equilibrio tra la quantità di materiale eroso lungo le foci principali e quella depositata lungo i tratti di costa contigui, con un aumento complessivo di 167.500 m2 della superficie di spiaggia, imputabile soprattutto alla variazione positiva nel tratto a di 460.500 m2. i periodi successivi sono caratterizzati da una dominante tendenza all’erosione che comporta variazioni negative della spiaggia nei tratti a e c, valutabili in un totale di circa 715.500 m2 per il 1954-1992 e di circa 107.600 m2 per il 1992-1998, cui corrispondono tassi annuali molto simili di rispettivamente 18.800 e 17.900 m2/anno circa. per il tratto immediatamente a sud del porto di termoli si verifica tra il 1954 e 1998 (o verosimilmente 1980?-1998), una variazione positiva complessiva dell’arenile di circa 140.000 m2 di cui ca. 30.000 m2 nel solo periodo 19921998. complessivamente risulta che la costa molisana ha subito una variazione negativa delle spiagge di circa 656.000 m2 durante gli ultimi 90 anni (1907-1998). facendo un’analisi per tratti si evidenzia innanzitutto un bilancio positivo complessivo per il tratto b, negativo invece per i tratti a e c. questi ultimi mostrano un comportamento del tutto dissimile in relazione alla loro tendenza all’erosione, come evidenziano i valori medi annui calcolati rispettivamente per i periodi 19541992 e 1992-1998. infatti, nel tratti a tale tendenza subisce un incremento, avendosi il passaggio da un valore medio di 10.800 a 18.800 m2/anno, mentre subisce una diminuzione nel tratto c dove si passa da 9.100 a 5.700 m2/anno. il tratto b, invece, con un valore complessivo di 97.329 m2 evidenzia la sua leggera tendenza all’avanzamento, e mostra una crescente tendenza alla progradazione con un valore medio che da 1.100 passa a 6.600 m2/anno circa. i calcoli effettuati evidenziano anche che è il tratto a, e quindi l’area della foce del trigno, ad aver fornito i contributi annuali più consistenti alla variazione negativa delle spiagge per i suddetti periodi. emerge inoltre chiaramente, che le variazioni negative di spiaggia tra il 1907 e il 1998 lungo l’intero litorale molisano (655.640 m2) grosso modo coincidono con quelle verificatesi nello stesso periodo nel tratto c (690.649 m2), dato che le variazioni negative e positive nei tratti a e b quasi si compensano. prescindendo dal primo periodo (1907-1954) contrassegnato ancora da consistenti variazioni positive della spiaggia nel tratto a – si evidenzia chiaramente che sono proprio i tratti costieri a e c, dotati di importanti foci fluviali, ad essere stati interessati da variazioni negative della spiaggia, mentre il tratto b, ad essi interposto, trae evidenti benefici dall’erosione dei sedimenti nel tratto a e loro successivo trasporto lungo costa verso sud. 27 fig. 5 variazioni della linea di riva e dei principali canali fluviali nel periodo 1954-1992. tratti costieri che hanno subito 1) marcato arretramento, 2) leggero arretramento 3) marcata progradazione, 4) leggera progradazione. changes of shoreline and main fluvial channels from 1954 to 1992. coast sectors affected by 1) marked retreat, 2) slight retreat, 3) marked progradation, 4) slight progradation. ppeerriiooddoo ttrraattttoo aa ttrraattttoo bb ttrraattttoo cc ttoottaallee 1907 1954 460.500 17.000 310.000 167.500 1954 1992 409.863 40.830 346.461 715.494 1992 -1998 -112.957 39.499 34.188 107.646 totale 62.320 97.329 690.649 655.640 tab. 1 variazioni positive e negative (-) della superficie di spiaggia (in m2) analizzate per periodi e tratti. positive and negative (-) variations of the beach surface (in m2) analysed for periods and sectors. l’evoluzione recente ... 44.. ddiissccuussssiioonnee ddeeii ddaattii l’analisi cartografica comparativa ha evidenziato una serie di modificazioni significative della linea di costa che possono riferirsi a due principali fasi evolutive del sistema costiero esaminato. una prima fase di prevalente progradazione che si conclude con la costruzione degli apparati deltizi del trigno e del biferno rilevabili dalle carte storiche (atlante geografico del regno di napoli di rizzi-zannoni, 1808; cartografia storica i.g.m.i. del 1869 e 1907), e una seconda fase in cui si assiste ad un progressivo smantellamento degli stessi apparati deltizi e all’arretramento progressivo, tuttora in corso, delle spiagge. più in dettaglio, l’evoluzione più recente si può schematizzare come segue: periodo <1800? – 1869 gli apparati deltizi dei corsi d’acqua principali che sfociano lungo la costa molisana si mostrano con una morfologia pronunciata a cuspide, suggerendo un bilancio positivo complessivo del sistema costiero. nel 1869, detti apparati deltizi appaiono del tutto giovanili e in attiva evoluzione. periodo 1869-1907 in base a quanto è stato accertato per il tratto c, è possibile ipotizzare una fase di relativa stabilità delle aree di foce. in questo periodo, infatti, non si registrano variazioni negative della foce del biferno, mentre avviene una consistente progradazione delle fasce costiere contigue, portando ad un bilancio costiero altamente positivo. periodo 1907-1954 gli apparati deltizi del trigno e biferno sono soggetti a forte erosione che determina un cambiamento fondamentale della loro fisionomia passando da fluvialdominated a wave-dominated. questa fase è accompagnata da una ridistribuzione del materiale eroso che contribuisce alla progradazione degli adiacenti tratti di costa che compensa in parte (tratto c) o completamente (tratto a) l’erosione lungo le foci. il bilancio complessivo è positivo. periodo 1954-1992 si assiste ad una intensa fase di erosione che causa arretramenti consistenti nei tratti a e c dove si completa lo smantellamento dei residui apparati deltizi. il bilancio è chiaramente negativo. mentre la tendenza all’erosione lungo la costa è già molto evidente nel 1954, i corsi d’acqua principali a deflusso adriatico, caratterizzati da regimi torrentizi e morfologie d’alveo del tipo braided nelle sezioni non confinate, appaiono ad alta dinamicità, come evidenzia anche la presenza di conoidi attivi agli sbocchi di vari bacini tributari (aucelli & rosskopf, 2000). periodo 1992-1998 l’erosione della linea di costa persiste con ritmi diversi nei tratti a e c. per il tratto a si assiste ad un incremento delle variazioni areali negative, mentre si registra un rallentamento del ritmo di erosione nel tratto c. il tratto b è caratterizzato da una accresciuta tendenza alla progradazione, ma il bilancio complessivo è comunque negativo. l’evoluzione riscontrata corrisponde pienamente al modello proposto da pranzini (1989, 1994) sulla evoluzione dei delta italiani nel periodo storico in relazione alle tappe morfoevolutive più recenti. le modificazioni rilevate testimoniano variazioni consistenti nel bilancio costiero, quindi uno squilibrio tra quantità di sedimenti disponibili e capacità del sistema costiero di rielaborare gli stessi. le eventuali cause naturali e/o antropiche di tali modificazioni, in prima analisi, andrebbero ricercate 28 fig. 6 variazioni della linea di riva e dei principali canali fluviali nel periodo 1992-1998. tratti costieri che hanno subito 1) marcato arretramento, 2) leggero arretramento, 3) marcata progradazione, 4) leggera progradazione. changes of shoreline and main fluvial channels from 1992 to 1998. coast sectors affected by 1) marked retreat, 2) slight retreat, 3) marked progradation, 4) slight progradation. p.p.c. aucelli et al. nelle variazioni di uno o più dei seguenti principali parametri: apporti sedimentari alle foci, livello marino (sia a lungo che breve termine), capacità erosiva delle onde, caratteristiche dei sistemi di correnti vicino costa e delle modalità di trasporto lungo costa, nonché relative interferenze con strutture protettive. le conoscenze finora acquisite non consentono di proporre un’analisi esaustiva delle potenziali cause, data soprattutto la mancanza di dati relativi agli aspetti meteo-marini e la necessità di approfondire le modalità di interferenza tra dinamica costiera e strutture protettive. l’attenzione è stata quindi per ora focalizzata su quei aspetti che possono aver influito in modo diretto od indiretto sulla disponibilità di sedimenti da immettere nel bilancio costiero. e’, infatti, la risposta differenziata dei vari tratti costieri esaminati che vede “penalizzati” proprio i tratti costieri dotati di maggiori foci fluviali (tratti a e c) che, a nostro avviso, è fortemente indicativa del fatto che la diminuzione degli apporti fluviali alle foci costituisca effettivamente una delle cause principali se non proprio la causa maggiore delle tendenze all’arretramento osservate. variazioni climatiche le condizioni meteo-climatiche esercitano un importante ruolo sia in relazione alle caratteristiche idrologiche dei corsi d’acqua sia alla dinamica costiera, oltre a condizionare lo sviluppo della copertura del suolo. riguardo le prime, in particolare, è da considerare innanzitutto la stretta relazione tra afflussi meteorici e deflussi liquidi, e tra quest’ultimi e il trasporto solido. riguardo la prima fase evolutiva distinta, l’influenza climatica andrebbe a tradursi principalmente in una diminuzione delle temperature ed un aumento degli afflussi meteorici, e conseguente incremento delle portate liquide dei fiumi e del trasporto solido, quest’ultimo favorito o meno anche da un degrado della copertura vegetazionale. dati interessanti circa il rapporto tra condizioni climatiche, trasporto solido e evoluzione della linea di costa emergono dallo studio di marabini (2000) che permette una rivalutazione del ruolo del clima rispetto alle varie influenze antropiche (spesso le uniche ad essere chiamate in causa). i dati riportati, a sostegno dell’influenza climatica globale, mettono in evidenza gli andamenti simili delle portate dei maggiori fiumi d’europa negli stessi periodi, e il rapporto tra variazioni di portata dei corsi d’acqua e pulsazioni climatiche freddo-umide riferibili alla piccola età glaciale, con l’aumento degli apporti solidi alla costa e l’avanzamento progressivo della costa dell’alto adriatico tra il 1600 e 1820. ovviamente, per l’area e il periodo di studio presi in esame dovrebbero considerarsi soprattutto le pulsazioni fredde verificatesi nella seconda metà del 1800, evidenziate dall’avanzamento dei ghiacciai intorno al 1850 e 1890 (röthlisberger, 1986; antonioli, 2000). in accordo con marabini (2000), in un simile contesto climatico l’equilibrio della zona costiera è regolato dal rapporto tra apporti solidi e frequenza delle mareggiate, e il suo avanzamento legato quindi al “prevalere” degli apporti solidi. circa la seconda fase evolutiva è possibile fare riferimento ad una serie di dati di carattere sia nazionale che locale. come evidenziano i dati riportati in vittorini (1991) sulle variazioni delle portate liquide e solide dei fiumi italiani dal 1921 al 1973, emerge una netta flessione del trasporto torbido unitario del 40% circa confrontando il periodo pre-bellico (1921-1943/44) con quello post-bellico (1954-1973). tralasciando l’influenza antropica, tale flessione è da legare secondo l’autore, oltre che ad una complessiva diminuzione delle portate liquide (non del tutto da imputare al decremento degli afflussi meteorici), ad una diminuzione della frequenza di eventi di piena che superino una determinata portata. infatti, per quanto riguarda i corsi d’acqua maggiori sul territorio italiano sarebbero soprattutto gli eventi di piena con portate superiori ai 500 m3/s a portare ad una percentuale apprezzabile la frazione sabbiosa del carico solido. che non esista un rapporto semplice tra deflussi idrici, trasporto solido e fenomeni di progradazione od erosione costiera, viene indicato per l’area di studio per esempio dal fatto che, mentre le evidenze morfologiche relative al 1954 indicano per il sistema costiero una situazione di non-equilibrio (con fenomeni di arretramento già in atto), i sistemi fluviali sembrano ancora godere di condizioni di equilibrio nel loro assetto planoaltimetrico, e di alta dinamicità e capacità di trasporto (aucelli & rosskopf, 2000). ciò potrebbe essere indizio di un’accresciuta dinamica costiera, tale da annullare l’equilibrio precedentemente raggiunto. a livello regionale, l’analisi dei dati pluviometrici (ministero dei lavori pubblici, servizio idrografico, 1997) evidenziano per il quarantennio 1951-1990 un decremento generale delle precipitazioni. i dati pluviometrici e idrologici esaminati per il bacino del fiume trigno (aucelli, 1999; aucelli & rosskopf, 2000) mettono in evidenza uno stretto legame tra afflussi meteorologici e deflussi liquidi, nonché consistenti variazioni degli afflussi annuali nel tempo. complessivamente, tali dati confermano la tendenza a diminuire delle precipitazioni che caratterizza quasi per intero la seconda metà del secolo scorso. in particolare, condizioni di maggiore piovosità contraddistinguono i periodi 1944-1949 e 19551964, cui si contrappongono periodi più aridi tra il 19501954 e 1965-1990, con un ulteriore calo delle precipitazioni medie annue dal 1980 in poi. circa il rapporto tra recenti fluttuazioni climatiche e variazioni del livello marino, i dati esposti in antonioli (2000) riferiscono di una media dei valori di risalita eustatica di 12-15 cm/secolo per gli ultimi 100 anni, e di 1mm/anno durante il diciannovesimo secolo. questi dati, ovviamente da considerare con prudenza, suggeriscono la presenza di un leggero innalzamento del livello marino al termine della piccola età glaciale, valutabile fino ad oggi in qualche decimetro al massimo. un tale innalzamento, con ogni probabilità, ha influenzato negativamente l’equilibrio del sistema costiero, favorendo l’erosione della spiaggia. variazioni dell’uso del suolo spunti interessanti circa le possibili influenze delle variazioni dell’uso del suolo sulla dinamica fluviale e quindi su quella costiera, sono offerti dai dati raccolti da di martino (1996) sull’evoluzione della copertura forestale nella regione molise, già oggetto di esame in aucelli & rosskopf (2000). l’analisi di tali dati, infatti, mette in evidenza una serie di interventi da parte dell’uomo che, a partire dal 1800, hanno massicciamente modificato le originarie coperture boschive. tra questi interventi, i disboscamenti hanno interessato in modo 29l’evoluzione recente ... diffuso i bacini idrografici maggiori e minori e i versanti collinari costieri. il taglio della legna spesso avveniva in modo abusivo ed a dispetto della legge forestale del 1826. le modificazioni indotte dallo sfruttamento dei boschi per pascolo (spesso eccessivo) e dalle stesse attività di disboscamento hanno favorito l’impoverimento e il degrado del suolo e la sua asportazione da parte delle acque di ruscellamento. l’attività di disboscamento è perdurata fino all’inizio del 1900, ed è stata scarsamente bilanciata da misure di rimboschimento, effettive solo a partire dalla prima metà del 1900 in concomitanza degli interventi di bonifica. per il periodo 1920-1971, le analisi statistiche effettuate mostrano una riduzione delle aree coltivate, compensata soltanto in parte da un aumento del pascolo, delle coltivazioni arboree e del bosco. l’abbandono delle campagne potrebbe aver contribuito ad una riduzione dell’entità di erosione del suolo con lo stabilirsi di coperture perenne a seguito del processo di naturalizzazione. interventi antropici sui sistemi fluviali tra le attività umane che maggiormente incidono sui sistemi fluviali, le estrazioni in alveo rappresentano un aspetto di primaria importanza sia per il sistema fluviale del trigno, interessato da una consistente attività di estrazione soprattutto a partire dagli anni ’60 (aucelli & rosskopf, 2000), sia per quello del fiume biferno. per quest’ultimo, i prelievi in alveo hanno assunto maggiore consistenza a partire dalla seconda metà degli anni ’60 in concomitanza della costruzione in contemporaneo della strada che percorre il fondovalle del biferno (la fondovalle bifernina) e della diga di ponte liscione (1966-1976). con l’invaso del bacino artificiale nel 1977, le aree di fondovalle e soprattutto l’alveo hanno subito un progressivo degrado dovuto ad una modificazione consistente del naturale dinamismo del fiume a seguito della riduzione e regimazione delle sue portate liquide (rilascio costante di ca. 1 m3/sec) che ha portato ad una “fossilizzazione” delle morfologie d’alveo, ben evidente dal confronto delle più recenti foto-aeree (i.g.m.i. 1977 e 1991) e delle ortofotocarte (1998). attualmente, gli apporti solidi sabbiosi giungenti ancora alla foce provengono essenzialmente dal bacino del torrente cigno. questo, oltre ad essere il maggiore sottobacino del fiume biferno, è l’unico nel settore a valle della diga ad avere una estensione superiore a 50 km2 (ca. 107 km2), ed ad essere impostato in prevalenza su litologie sabbioso-ghiaiose. alle attività di prelievo si affiancano gli interventi di sistemazione dei corsi d’acqua principali, realizzati lungo il corso del trigno e del biferno durante l’ultimo trentennio circa. questi consistono principalmente nella realizzazione di arginature (presenti estesamente sul trigno dalla confluenza del torrente rivo in poi, e sul biferno nel tratto a valle della diga), e di armature dei tratti fluviali in corrispondenza di attraversamenti fluviali come ponti e viadotti lungo le strade di fondovalle (fondovalle trigno e biferno). le opere di arginatura sono state spesso accompagnate da interventi di rettificazione (come ad esempio il taglio del meandro nella parte terminale del biferno all’altezza dell’odierno nucleo industriale). interventi finalizzati a limitare l’erosione verticale come la messa in posto di briglie e traverse fluviali, hanno interessato in modo massiccio soprattutto i bacini tributari, contribuendo ad un ulteriore intrappolamento di sedimenti. 55.. ccoonnssiiddeerraazziioonnii ccoonncclluussiivvee il presente studio ha consentito di ricostruire le recenti variazioni della linea di costa lungo il litorale molisano. in particolare, questo studio ha evidenziato la tendenza, a partire dall’inizio del 1900, all’arretramento della costa che assume entità rilevanti soprattutto nella seconda metà del secolo scorso. circa le possibili cause di tali variazioni, i dati discussi precedentemente mettono in evidenza il possibile rapporto tra fenomeni di avanzamento e arretramento della linea di costa con modificazioni a breve termine delle condizioni climatiche. a queste, tuttavia, si sovrappongono modificazioni indotte dall’uomo (cambiamenti dell’uso del suolo, prelievo di inerti sui fiumi e sistemazioni idrauliche) che vanno a rinforzare se non a sostituire dal punto di vista dell’incidenza tali influenze climatiche. emerge inoltre chiaramente, che la conoscenza dei parametri meteomarini (direzione ed intensità dei venti, frequenza delle mareggiate, direzione del drift litoraneo) e delle caratteristiche topografiche dei fondali, è fondamentale per comprendere la tendenza evolutiva più recente ed attuale del sistema costiero, e l’interferenza tra il suo dinamismo e le opere di protezione costiera. l’analisi dei parametri meteo-marini, insieme a quelli meteo-climatici ed idrologici, portata indietro nel tempo per quanto possibile, potrebbe inoltre fornire ulteriori indicazioni utili circa il ruolo del clima nella dinamica costiera. bbiibblliiooggrraaffiiaa aminti p. & pranzini e. (a cura di) (1993) la difesa dei litorali in italia. edizioni delle autonomie, roma. p. 328. antonioli f. (a cura di) (2000) – le fluttuazioni del clima nel corso dell’olocene: stato dell’arte. il quaternario, 1133 (1), 95-128. assessorato ai lavori pubblici della regione molise (2001) studio specialistico relativo alla erosione marina sulla intera costa della regione molise. campobasso. aucelli p.p.c. (1999) – analisi morfodinamica del bacino del fiume trigno: distribuzione, entità e cause dei fenomeni di alveo e di versante. dottorato di ricerca in scienze ambientali: uomo e ambiente. xii ciclo. università degli studi del molise, 306 pp. aucelli p.p.c. & rosskopf c. (2000) last century valley floor modifications of the trigno river (southern italy): a preliminary report. geogr. fis. dinam. quat., 2233, 105-115. aucelli p.p.c., iannantuono e. & rosskopf c.m. (2004) – evolutive trends and present morphodynamics along the molise coast and their relationship to shore protection structures (southern italy). atti del convegno: 4th european congress on regional geoscientific cartography and information systems, bologna, giugno 2003 (in stampa). di martino p. (1996) – storia del paesaggio forestale del molise (sec. xix-xx). lampo, campobasso, 171 pp. 30 p.p.c. aucelli et al. giorgi g., girardi a., marabini f & zunica m. (1984) – evoluzione delle coste abruzzesi-molisane ed analisi di alcuni paraggi significativi. mem. soc. geol. it., 2277, 569-577. marabini f. (2000) – effetti sull’erosione costiera dei fenomeni climatici recenti: l’esempio del litorale nord adriatico. in: mare e cambiamenti globali. aspetti scientifici e gestione del territorio (a cura di sergio silenzi). convegno icram, 25/26 febbraio 1999, roma, 119-134. ministero dei lavori pubblici, servizio idrografico (1997) precipitazioni annue per il quarantennio 19511990: bacini con foce al litorale adriatico dal salinello al fortore. pubbl. n. 29 del servizio, fasc.1°, 72. parea g.c. (1978) trasporto dei sedimenti ed erosione costiera lungo il litorale fra il tronto ed il fortore (adriatico centrale). mem. soc. geol. it., 1199, 361-367. pranzini e. (1989) – a model for cuspate river delta erosion. 6 th symposium on coastal and ocean management/asce. charleston, sc. coastal zone ’89, 4345-4357. pranzini e. (1994) – bilancio sedimentario ed evoluzione storica delle spiagge. il quaternario, 77 (1), 197204. rizzi-zannoni g.a. (1808) – atlante geografico del regno di napoli. röthlisberger f. (1986) – 10.000 jahre gletschergeschichte der erde. verlag sauerländer, 395 pp. vittorini s. (1991) – la diminuzione del trasporto torbido nei fiumi italiani tra il periodo prebellico e quello attuale. geogr. fis. dinam. quat., 1144, 252-258. zunica m. & girardi a. (1984) atlante delle spiagge italiane. cnr, selca, firenze. lavoro realizzato con il contributo dei fondi di ateneo 2000 (quota di co-finanziamento cofin 2002, responsabile nazionale giuliano rodolfi, responsabile scientifico dell’unita di ricerca carmen maria rosskopf). 31 ms. ricevuto il 20 dicembre 2003 testo definitivo ricevuto il 7 febbraio 2004 ms. received: december 20, 2003 final text received: february 7, 2004 l’evoluzione recente ... amq short notes 26_2 zerboni divito monegato available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 25 (2), 2012, iii v report on the geoevent “discovering volcanoes”, sponsored by aiqua, at the vesuvius observatory museum (ingv) mauro antonio di vito, giovanni ricciardi, tullia uzzo, sandro de vita istituto nazionale di geofisica e vulcanologia, sezione di napoli osservatorio vesuviano, naples, italy corresponding author: m.a. di vito <mauro.divito@ov.ingv.it> abstract: a brief summary of the activities carried out on 20th october 2012 at the vesuvius observatory museum for the geoevent of planet earth week, “discovering volcanoes”, sponsored by aiqua. keywords: osservatorio vesuviano, communication, earth sciences, volcanoes . on october 20th 2012, the planet earth week geoevent “discovering volcanoes”, an event organized under the patronage of the italian association for quaternary research (aiqua), the vesuvius observatory museum (move, fig. 1) played host during an interesting day devoted to instruction about volcanic phenomena. this occasion for awareness-raising was given an enthusiastic reception by members of the public thanks to the communication skills of numerous researchers who were able to combine science, history and art so as to convey important information regarding volcanic hazards, using as a base extraordinary records from the past, some of which are unpublished. in the vesuvius observatory museum’s prestigious luigi palmieri room (fig. 2), several films of vesuvius eruptions were shown, beginning with a short footage from 1898 made by the lumière brothers two years after their invention of the moving picture camera. the two brothers visited naples that year to film scenes of daily life and city landmarks. in the background of their shots of the dock, vesuvius in eruption may be seen. the lumière brothers thus filmed a volcanic eruption for the first time ever, illustrating the activity of vesuvius which in the four years from 1895 had formed colle umberto, a lava dome named after the king of italy, umberto i. pa g iii fig. 1 the historic seat of the vesuvius observatory, first home of the oldest volcanological observatory in the world. di vito a. et al. iv fig. 2 moments during the event in the palmieri room of the prestigious seat of the vesuvius observatory in ercolano. fig. 3 the collection of lava medals on display for the occasion in the room that housed the volcano exhibition: multimedia voyage into the world of volcanoes. another footage of great interest and scientific value was that of the 1906 eruption, vesuvius’ largest of the 20th century. the seven-minute-long film was made by two neapolitan photographers, the troncone brothers, who sent it to a cinema exhibition in paris, where the spool was lost. a copy of the footage turned up as part of a popular film about volcanoes and earthquakes produced in america in the 1920s – today part of the patrimony of the vesuvius observatory museum. the recovery of this film was of great importance, since apart from the unique 1906 shots, it also contains footage taken immediately after the 1908 messina earthquake by a sailor on the russian battleship makarov, which intervened to give aid to the populace. the last film screened, in full, was that of the 1944 eruption made by the allied forces during the second world war and donated to the director at the time, giuseppe imbò. more than 300 members of the public took part in the geoevent, showing a keen interest in and appreciation of the initiative, and afterwards participated in the visit to the museum, where expert guides led those present on an extraordinary journey through the world of italian volcanoes and the geothermal energy that can be obtained from them. by means of panels and exhibits on italian volcanoes and geothermal energy, audiovisuals, a multimedia panel and a 3d-movie room, visitors were given information about italy’s active volcanoes and the danger they pose, and the systems adopted by the national institute of geophysics and volcanology (ingv) for monitoring their activities. the visit also permitted an appreciation of what may be considered the vesuvius observatory museum’s treasures, the precious assemblage of rocks, volcanic ash and lava medallions housed in the old bourbon building, and in particular the collections of meteorological and seismological instruments, from the oldest electrometers and seismoscopes to the world’s first electromagnetic seismograph, built by palmieri in 1856, up to more modern versions. the museum also recounts the progress of volcanology and seismology, which owed their birth and much of their development to past directors of the vesuvius observatory, starting with macedonio melloni, luigi palmieri, giuseppe mercalli and alessandro malladra. particular interest was aroused by the collection of medallions in vesuvian lava, the only one of its kind, which bears witness to moments in the social, political and scientific world that surrounded the volcano; they were stamped onto still-fluid lavas (fig. 3) that erupted from vesuvius between 1819 and 1944. the event also provoked considerable interest in the national and international press, which released pictures of the day’s highlights in italy and numerous other countries. ms. received: september 6, 2013 final text received: september 6, 2013 discovering volcanoes v vi imp. bertacchini-cenciaioli uunnoo ssgguuaarrddoo ssuullllaa cciittttàà rroommaannaa ddii ooccrriiccuulluumm ((uummbbrriiaa,, iittaallyy)) mmiilleennaa bbeerrttaacccchhiinnii11 && lluuaannaa cceenncciiaaiioollii22 1d.to di scienze della terra, università di modena e reggio emilia, modena, italy 2soprintendenza per i beni archeologici dell’umbria, perugia, italy riassunto otricoli è un centro abitato nel sud dell’umbria, situato in un territorio limitato ad est dai rilievi della catena appenninica e ad ovest dal ”fiume di roma”, il tevere. arroccato su una rupe, domina dall’alto le vestigia di quella che fu, in epoca romana, otricoli “apud tiberim” (al tevere) nota come ocriculum. ocriculum sorse e si sviluppò in età augustea, tra il i sec. a.c. e il ii sec. d.c, in una zona pianeggiante e degradante verso il tevere e divenne presto un fiorente centro commerciale. la città crebbe difesa naturalmente da due contrafforti in tufo, sopra e a ridosso dei quali furono costruiti importanti edifici e ville patrizie. nell’area affiora una successione sedimentaria del pliocene sup.-pleistocene inf., medio di ambiente marino passante ad ambiente fluviale e una copertura, variamente estesa, di rocce piroclastiche del pleistocene medio prodotte dal vulcano di vico. tra la fine del vi e il vii sec. d.c. l’azione sinergica di fattori naturali e antropici (caratteristiche litologiche e morfologiche, deterioramento climatico e situazione di degrado conseguente alla crisi dell’impero romano) costrinse gli abitanti ad abbandonare l’antica città di ocriculum. abstract otricoli is a village located in the south of the umbria region (central italy). it is perched in a territory limited on the eastern side by the apennines chain and the west by the tiber river. from the top of a hill otricoli dominates the ruins of the roman village of ocriculum. ocriculum was founded in the 1st century b.c. and developed during the 2nd century a.d. it was placed in a flatten area declining towards the tiber river and soon it became a prosperous commercial centre. marine sediments of the late pliocene-early pleistocene and fluvial sediments of the early-middle pleistocene covered by middle-late pleistocene pyroclastic rocks cropping out in the area. in the early times of the roman village two barrier-walls were built to widen the plain area. the romans filled in and levelled the valley at various times in order to obtain a wide plain area while the substructures were built as foundations of public buildings and to stabilise the slope under the forum. in the first phase a barrier-wall was built in the lower part of the stream (close to the r. tiber). consequently the san vittore stream began wandering and accumulating sediments. later a second barrier-wall had to be built, on the upper side of the stream, beside the baths. the san vittore stream was also channelled between the two barrier-walls for about 300 m in order to better control the flood plain. natural factors and human activities caused ocriculum’s deterioration that forced the inhabitants to abandon the town in the period between the end of the 6th and 7th centuries a.d., during the climatic minimum of the early middle ages. the cold, wet climatic conditions certainly facilitated the decline of the territory, already worsened by the consequences of the fall of the roman empire. the transfer of the inhabitants of ocriculum to the upper village is not clearly described in historical documents, although it is certain that there was no life in this roman village after the 7th century a.d parole chiave: città romana, sedimenti marini, rocce piroclastiche, caratteristiche litologiche, morfologiche, deterioramento climatico. keywords: roman village, marine sediments, pyroclastic rocks, natural factors, deterioration, climatic minimum. il quaternario italian journal of quaternary sciences 1166(2), 2003, 207-216 11.. iinnttrroodduuzziioonnee il territorio di otricoli, in provincia di terni, al confine tra l’umbria e il lazio, è limitato ad oriente dai rilievi montuosi dei monti di amelia e narni e ad occidente dal “fiume di roma”: il tevere (fig. 1). la radice greca del nome ocris (monte) suggerisce la posizione rilevata e arroccata su una rupe del paese, all’ombra del quale si ergono le vestigia di quella che fu, in epoca romana, otricoli “ apud tiberim” (al tevere) nota come ocriculum. le fonti storiche riportano come ocrea il nome del primo insediamento sorto nella zona più rilevata, situato al confine tra il territorio umbro e quello sabino. la posizione dominante che ocrea occupava sull’alveo del tevere era accentuata ancor più dalla presenza di un castello (martinori, 1929), del quale oggi non rimangono tracce. ocriculum sorse in età augustea nel i sec. a.c. e si sviluppò nel ii sec. d.c, in una zona pianeggiante e degradante verso il tevere, occupando un’area di 36 ettari circa. in periodo tardo imperiale il nome cambiò in utriculum da cui derivò la forma medievale utricoli. l’insediamento di epoca romana divenne presto un nodo strategico tra varie vie di comunicazione e un fiorente centro commerciale. attraversato dalla via flaminia, ocriculum costituiva una sosta importante nel lungo collegamento tra roma e ariminum (rimini); mentre l’approdo di ocriculum sul tevere, noto come “porto dell’olio”, rappresentava uno dei principali porti fluviali 208 m. bertacchini & l. cenciaioli tiberini. le cause che portarono gli abitanti di ocriculum ad abbandonare l’area posta a quota inferiore e a fare ritorno alla “ocris” sono controverse. secondo pietrangeli (1978) l’abbandono avvenne nell’alto medioevo, forse nella seconda metà del vii sec., per “sfuggire all’aria malsana della zona soggetta a inondazioni e a cambiamenti del letto del tevere”. secondo bonomi ponzi (1995) lo spostamento verso l’altura sarebbe avvenuto tra viii e ix sec., per cause legate non tanto ad un diffuso senso di insicurezza quanto allo stato di impaludamento e di conseguente incuria del territorio (scomparsa di cariche statali quali curatores viarum e riparum). tali condizioni di degrado accentuarono lo stato di distruzione in cui l’umbria peraltro già si trovava, perché colpita da carestie e pestilenze nel v-vi sec. d.c. e soggetta a devastazioni e saccheggi durante le invasioni barbariche. in particolare, nel 772, desiderio re dei longobardi, dirigendosi verso roma, espugnò ocriculum, portando devastazione all’abitato e causando l’abbandono dell’antico tracciato della via flaminia che fu spostata più verso monte (martinori, 1929). 22.. ddaattii aarrcchheeoollooggiiccii 22..11 llaa cciittttàà i resti più antichi che rimangono dell’abitato “di monte” sono rappresentati da tratti di mura risalenti alla fine del iv sec. a.c. primi decenni del iii sec. a.c., rimasti inglobati nelle mura castellane dell’attuale otricoli. inoltre, nelle immediate vicinanze del sito archeologico di ocriculum, in località querciacupa e nel podere lupacchini, sono state individuate alcune cavità artificiali utilizzate come tombe, ricavate sul fronte di affioramento dei rilievi di tufo; altre sepolture sono del tipo a fossa. queste necropoli arcaiche, attribuibili al viivi sec. a.c., attestano nell’area, insieme a materiali frammentari, la presenza di insediamenti appartenenti alla prima età del ferro (cenciaioli, 2001). un’altra tomba arcaica di pregevole architettura è stata rinvenuta all’inizio dell’anno 2003 da cenciaioli in località querciacupa, sempre nel coronamento esterno del tavolato in tufo; sono attualmente in corso studi di carattere archeologico e geologico per caratterizzare e documentare l’area di rinvenimento. tra i resti di età arcaica rinvenuti nel pod. civitelle è presente una terracotta architettonica con fregio figurato in rilievo che rappresenta una teoria di armati. dall’area centrale della città antica provengono inoltre sporadiche terrecotte architettoniche, tra le quali un busto di figura maschile nudo (fig. 2) databile tra il iv e il iii sec. a.c. (cenciaioli, 2001), che attestano uno sviluppo della città in età classica ed ellenistica. dal i sec. a.c. in poi la storia di ocriculum si può leggere attraverso i monumenti, molti dei quali costruiti tra il i sec. a.c. ed il i sec. d.c. in opera reticolata (tecnica muraria del periodo repubblicano) e come raccolti intorno al torrente s. vittore. le terme furono costruite nel ii sec. d.c. e sono, per ovvie ragioni, il monumento più vicino al corso d’acqua; mentre il teatro, le grandi e le piccole sostruzioni, alle spalle delle terme, si affacciano ad una cinquantina di metri dall’alveo. la città doveva essere ricca di edifici splendidamente decorati e il suo centro, dove sorgevano la basilica e il foro, dei quali si è persa ogni traccia, era probabilmente posto nel pod. civitelle (cenciaioli, 2002b). gran parte delle fabbriche cittadine erano costruite in tufo e alcune strutture come l’anfiteatro (fig. 3) e il teatro erano, in parte, scavate direttamente nel tavolato tufaceo. 22..22 llaa vviiaa ffllaammiinniiaa la città era attraversata dalla via flaminia che, fiancheggiata da querce e monumenti funerari (cenfig. 1 ubicazione dell’antica città romana di ocriculum e dell’attuale centro di otricoli. location of the roman town of ocriculum and the present-day town of otricoli. fig. 2 terracotta raffigurante figura maschile (da cenciaioli, 2001). terracotta of male figure (by cenciaioli, 2001). ciaioli, 2000), si snodava tra la dolce morfologia dell’area, assecondando ondulazioni e sinuosità del rilievo. la via consolare, realizzata dal console c. flaminio nel 220-219 a.c., oltrepassato il tevere presso la località pile di augusto, entrava in umbria circa un chilometro a sud di ocriculum, dopo un percorso di 44 209uno sguardo sulla città romana di ocriculum miglia da roma. una volta superato il castello delle formiche, attraversava il tavolato di tufo meridionale con un percorso rettilineo, circa parallelo a quello dell’attuale via flaminia, mantenendosi sempre intorno a 94 m di quota, e raggiungeva le località pianacci ed essiccatoio (messineo, 1993). lungo questo tratto, accompagnato da numerosi monumenti funerari, il tracciato appare ora coperto da un manto di ciottoli arrotondati e appiattiti (usati come fondo stradale) che scompaiono a pochi metri ai lati della strada. la “via publica” continuava fiancheggiando l’anfiteatro, guadava il torrente s. vittore in corrispondenza del monumento funerario a torre (fig. 4) e giungeva finalmente verso l’area urbana di ocriculum. è all’ingresso della città che uno scavo condotto dalla soprintendenza per i beni archeologici dell’umbria ha rinvenuto un tratto della via flaminia basolato con lava leucitica (fig. 5), delimitato da una fonte pubblica e da un monumento funerario rotondo a tamburo, rivestito di blocchi di travertino (cenciaioli, 2000, 2002a, b). la strada doveva poi proseguire verso il foro, seguendo un percorso che saliva prima blandamente alle spalle delle piccole sostruzioni, quindi più ripidamente verso la chiesa di s. fulgenzio o del buon consiglio fino a raggiungere l’abitato di monte (cenciaioli, 2000; 2002a). a testimonianza di questo percorso, nel versante sotto di esso e rivolto a nord, nei pod. cisterna e carpineto, si rinvengono frammenti e blocchi di lava leucitica sino a veri e propri basoli, che un tempo dovevano formare il basolato stradale. 22..33 ggllii ssccaavvii aarrcchheeoollooggiiccii i primi scavi della città romana furono condotti nella seconda metà del settecento, sotto il pontificato di pio vi. la direzione dei lavori fu affidata all’architetto giuseppe pannini che, nel testo pubblicato da g.a. guattani (1784-1805), definì questi scavi “senz’alcun dubbio tra i più fecondi del secolo”. sempre il guattani pubblicò i disegni del pannini relativi alla pianta della città e ad alcuni monumenti, in parte integrati con deduzioni personali dell’autore (pietrangeli, 1978). un esempio è fornito dal disegno delle “grandi sostruzioni”, rappresentate dal pannini come un edificio simmetrico rispetto ad un’asse centrale e, per questa simmetria, interpretato come un antico alloggiamento militare. al contrario pietrangeli (1978), rilevando un’accentuata asimmetria tra le due ali delle grandi sostruzioni, perché probabilmente costruite in epoche diverse, motivò la costruzione del complesso con due esigenze. innanzi tutto, vi era la necessità di sostenere il terreno immediatamente alle spalle del complesso e a valle del foro così da migliorarne la stabilità riducendone la pendenza, e per creare, al contempo, un fronte monumentale verso roma e il tevere. l’imponente costruzione, pertinente probabilmente ad un santuario del tipo di giove anxur a terracina, doveva sostenere un edificio pubblico, forse un tempio (cenciaioli, 2000), di cui non rimane traccia. nel corso dell’ottocento ocriculum fu soggetta a sporadici interventi di scavo, anche sostenuti dalla sensibilità artistica dell’epoca a rappresentare rovine archeologiche in dipinti e litografie, la stessa ocriculum fu usata come soggetto, interpretato in stile romantico, in una litografia francese (papi, 2001). fig. 3 uno scorcio dell’anfiteatro e sullo sfondo il paese di otricoli. the amphitheatre and the village of otricoli in the background. fig. 4 due monumenti funerari lungo la via flaminia, a nicchia (sulla destra) e a torre (sulla sinistra). tower and nich tombs along the flaminia road. fig. 5 tratto della via flaminia basolato con blocchi di lava leucitica. the flaminia road’s paved stretch with leucitic lava blocks 210 gli scavi ripresero nella seconda metà del novecento, condotti dal dott. u. ciotti, furono indagati l’anfiteatro, le terme, il teatro e, in parte, le grandi sostruzioni. negli ultimi decenni le ricerche sono state riprese dalla soprintendenza per i beni archeologici dell’umbria (a cura della dott. a.e. feruglio), con scavi e saggi in alcuni punti della città romana, con lo scopo soprattutto di ricostruire esattamente il sito archeologico. di recente le indagini hanno interessato la zona appena al di fuori dell’area urbana, mettendo in luce il monumento funerario rotondo e il tratto della via flaminia descritti in precedenza. l’importanza di ocriculum come centro di commercio e di transito è suggerita dall’assenza di mura difensive intorno alla città e dalla presenza di monumenti di rappresentanza e di strutture di prestigio, come attestano le tracce di ville rustiche e di residenze estive appartenenti ai “nobilis” romani, tra i quali, ad esempio, tito annio milone (uccisore di clodio, 53 a.c.), pompea celerina (suocera di plinio il giovane) e la famiglia manlia (11-84 a.c.) (cenciaioli, 2000; martinori, 1929). le ville rustiche, sorte con la centuriazione dei terreni agricoli nella seconda metà del i sec. a.c., corrispondono spesso a proprietà sorte in questa parte dell’umbria per la mitezza del clima e la bellezza del paesaggio (“ville d’otium”); sono aziende agricole produttrici di cereali e vino, o artigianali, produttrici di laterizi (bonomi ponzi, 1995). le “coppe di popilio”, ad esempio, sono stati famosi manufatti in terracotta rossa non verniciata prodotti in ocriculum, mentre, in età imperiale, la presenza di cave di argilla a poca distanza dalla città romana ha favorito lo sviluppo di importanti fabbriche di tegole e mattoni. 33.. aassppeettttii mmoorrffoollooggiiccii il territorio che ospita il sito archeologico di ocriculum presenta una morfologia abbastanza morbida e dolce, interrotta talvolta da pareti scoscese. l’insediamento è situato in un’ampia conca, che si restringe e approfondisce avvicinandosi al tevere, mentre è racchiusa ai lati tra due contrafforti naturali in tufo, dall’evidente carattere difensivo, che si elevano a quote di poco superiori a 80 m. il potere erosivo delle acque superficiali, unitamente alla facile erodibilità dei terreni affioranti, sono la chiave per comprendere l’evoluzione morfologica di questo sito archeologico. il tevere e il torrente s. vittore sono gli elementi morfologici che più hanno influenzato lo sviluppo della città di ocriculum: il tevere in quanto importante via di comunicazione fluviale e il torrente s. vittore perché direttrice attorno alla quale è cresciuta la città. l’antico percorso del fiume di roma è suggerito, oltre che da vecchi toponimi testimoni di situazioni passate, dalla presenza di terrazzi fluviali che delimitano le sponde dell’antico alveo, in parte celati da una vegetazione rigogliosa. il toponimo fiume morto, ad esempio, assegnato ad un’ansa fluviale attualmente interrata e bonificata, ricorda come il tevere lambisse con un ampio meandro il versante sotto all’abitato di monte (otricoli), dove sorgeva il “porto dell’olio”, mentre scorreva ad una ventina di metri di distanza rispetto all’attuale riva del versante su cui sorse ocriculum. nel corso del tempo l’impetuosità del tevere ha modellato i versanti che delimitano il suo tracciato, innescando fenomeni di erosione talvolta anche molto intensa per scalzamento al piede del pendio. esempi riconducibili a questi fenomeni franosi si osservano tuttora al margine dei tavolati di tufo che si affacciano sul fiume, o si rilevano nella zona del “porto dell’olio” a testimoniare l’antico tracciato fluviale. in particolare nel 1688, in seguito al verificarsi di fenomeni franosi nella zona del porto, la congregazione del buon consiglio inviò sul posto l’architetto francesco sforzini. sforzini suggerì una nuova sistemazione della zona portuale, durante la quale il porto fu spostato provvisoriamente sotto il tavolato di tufo di s. vito (il tavolato che delimita a nord la valle di ocriculum). la strada che scendeva al porto e si distaccava dalla via flaminia in località crocefisso, fu rifatta nel 1720 con un percorso analogo a quello attuale (pietrangeli, 1978). il “porto dell’olio” fu utilizzato con frequenza fino alla fine del ’700, a conferma che il percorso del tevere, in questo tratto, è rimasto pressoché invariato per secoli. olio, vino, grano e altri generi commestibili erano tra i prodotti più commerciati e, soprattutto, legna tagliata nei boschi circostanti otricoli; come attesta un recente rinvenimento avvenuto nell’area archeologica, relativo ad un addetto alla pesatura dei carichi di ligna (cenciaioli, 2000). dalla fine del ’700 in poi il transito fluviale si arrestò in seguito ad un aumento progressivo del livello del fiume (pietrangeli, 1978) che rendeva impossibile il traino delle imbarcazioni (è solo a partire dal 1804, chirografo del 17 ottobre 1804 di pio vii, che per il tiro dei “navicelli” si cominciarono ad usare bufali anziché uomini). il tracciato del torrente s. vittore ha subito anch’esso dei mutamenti nel corso dei secoli determinati principalmente da interventi di natura antropica che bertacchini (2002), sulla base di rilevamenti effettuati sul terreno, di osservazioni geologico-geomorfologiche e dei resti di manufatti di età romana ancora osservabili, ha ipotizzato essere stati effettuati in fasi successive, attribuendo all’opera dei romani una serie di oculati interventi di ingegneria idraulica. in particolare bertacchini (2002) ha supposto che in epoca romana, antecedente o contemporanea la costruzione delle terme, possa essere stata realizzata una deviazione del torrente s. vittore con il proposito sia di impedire un approfondimento erosivo dell’alveo, sia di stabilizzare e sanare l’area valliva che era stata prescelta per costruire l’abitato di ocriculum. il corso d’acqua fu per questo imbrigliato e incanalato in un condotto sotterraneo in muratura, per una lunghezza di circa 300 m (cenciaioli, 2000). la canalizzazione attraversava la zona delle terme e delle grandi sostruzioni sino al teatro, all’altezza del quale il torrente riprendeva il suo alveo sino a sfociare nel tevere, non lontano dalla chiesa di s. vittore. le terme poterono essere costruite nel ii sec. d.c. su un’area pianeggiante, livellata e sistemata artificialmente. l’articolata opera di livellazione fece uso di due spessi muri di sostegno disposti normalmente all’asse della valle con la funzione di briglia (bertacchini, 2002). un primo muro fu posto a valle verso il tevere (fig. 6a), quasi di fronte al teatro, il successivo invece a monte a fianco alle terme (fig. 6b). m. bertacchini & l. cenciaioli 211 44.. aassppeettttii ggeeoollooggiiccii ee ggeeoommoorrffoollooggiiccii nella zona oggetto di studio affiora una successione del pliocene sup.-pleistocene inf., medio recentemente descritta da mancini et al. (2001a, b) e composta da sedimenti inizialmente di ambiente marino passanti a depositi di ambiente fluviale continentale, ai quali si sovrappongono materiali piroclastici prodotti dal vulcano di vico (fig. 7). la successione sedimentaria di ambiente marino inizia con argille e argille sabbiose di colore grigio, grigio piombo, con abbondante malacofauna, di ambiente di piattaforma e di transizione infra-litorale, dell’unità delle “argille sabbiose di ambiente marino” del pliocene sup.pleistocene inf. (mancini et al., 2001a, b). caratteristico è l’affioramento in prossimità della confluenza tra il torrente san vittore ed il tevere: le argille grigiastre appaiono variegate da sottili livelli chiari dovuti a concentrazioni di resti di organismi bentonici di ambiente marino di piattaforma e spiaggiati che, a luoghi, sottolineano la blanda stratificazione debolmente inclinata verso est-nord est. verso il tetto di quest’unità la componente sabbiosa diviene progressivamente più abbondante sino a prevalere. segue l’unità delle “sabbie siltose e silt di ambiente marino” di ambiente di piattaforma del pliocene sup.pleistocene inf. (mancini et al., 2001a, b); sono formate da sabbie a laminazione incrociata contenenti orizzonti più cementati tipo beach rock e conglomerati (fig. 7). quest’ultimi sono generalmente costituiti da ciottoli poligenici di piccole e medie dimensioni, provenienti dalle formazioni della successione umbro-marchigiana, discretamente arrotondati e immersi in abbondante matrice limoso-sabbiosa. all’unità delle “sabbie siltose e silt di ambiente marino” si sovrappone l’unità continentale di “civita castellana” di ambiente fluviale del pleistocene inferiore terminale-pleistocene medio iniziale (mancini et al., 2001a, b). l’unità di civita castellana si presenta come un conglomerato a scarsa matrice sabbiosa, a luoghi ben cementato, con ciottoli ben arrotondati, anche appiattiti, di diversa natura, ma prevalentemente calcarea e selciosa (selce nera e rossa). la dimensione dei ciottoli varia da centimetrica a pluricentimetrica. all’interno di quest’unità sono presenti lenti siltose gradate e poco cementate con spessore dell’ordine del decimetro. i rilievi più elevati del territorio otricolano (quote di poco superiori a 200 m) sono formati dai depositi ghiaiosi dell’unità di civita castellana (fig. 7); mancini et al. (2001a, b) indicano per detta unità uno spessore massimo di 120 m che si riduce a poco più di 20 m nell’area di studio. la successione sedimentaria continua con un deposito ghiaioso a cemento calcareo potente qualche metro, formato da elementi calcarei, selciosi e vulcanici anche decimetrici della “unità di rio fratta” (fig. 7) del pleistocene medio terminale (mancini et al., 2001a, b). questo deposito ghiaioso affiora in ottima esposizione lungo tutto il versante affacciato verso il tevere a sud di ocriculum, al di sotto del bancone tufaceo, e a tetto passa ad un intervallo formato da sabbie grossolane a cemento calcareo spesso circa 30 cm, forse correlabile con la “unità di fiano” della fine del pleistocene medio (mancini et al., 2001a, b). il materiale vulcanico che ricopre i sedimenti descritti in precedenza è associato all’attività dell’apparato vicano situato ad un centinaio di chilometri a sud ovest di otricoli. questo materiale, indicato come “tufo rosso a scorie nere” (fig. 7), è riconducibile alle ultime fasi eruttive del complesso vulcanico vicano che mancini, et al. (2001a, b) riferiscono all’ignimbrite c vicana di 155.000 anni fa. i tavolati in tufo rendono particolare il paesaggio che qui si osserva. le superfici pianeggianti dei tavolati, tra 82 e 90 m di quota, se da un lato fianchegfig. 6 i romani colmarono e livellarono la conca di ocriculum in diverse fasi con lo scopo di ottenere un’ampia zona pianeggiante. a) nella prima fase fu costruito un muro di sostegno con la funzione di briglia nella parte inferiore del torrente s. vittore, in prossimità del teatro. b) nella fase successiva fu costruita una seconda briglia più a monte del corso d’acqua, vicino alle terme. the romans filled and levelled the valley of ocriculum in different phases to obtain a wide plain area. a) in the first phase a barrier-wall was built in the lower part of the stream (close to the tiber river). b) in the next phase the second barrier-wall was built in the upper side of the stream (close to the baths). uno sguardo sulla città romana di ocriculum 212 giano le discontinue creste dell’unità di “civita castellana”, dall’altro scendono bruscamente con pareti subverticali, per svariati metri, verso morfologie più dolci e depresse, impostate nelle litologie a sabbie e argille sottostanti. il materiale tufaceo è a composizione tefriticofonolitica (baldi et al., 1974; mancini et al., 2001a, b) ed è generalmente di colore grigio scuro con inclusi nerastri di dimensione variabile da centimetrica a decimetrica. i depositi descritti sino ad ora, sia quelli di origine sedimentaria sia quelli di origine vulcanica, sono caratterizzati da uno scarso grado di cementazione che, unitamente all’inclinazione, pur non eccessiva, dei versanti dove affiorano, facilita una loro mobilizzazione in concomitanza di eventi piovosi intensi e/o prolungati. la diversa permeabilità di questi depositi e dei loro prodotti di alterazione, giustifica la presenza di numerose sorgenti nella zona, come ricordano, ad esempio, i toponimi fontana, fontana cannella, alcune delle quali ad uso civile come la sorgente della fonte acquabona, ben nota anche nel passato come recita una lapide del 1500, posta sulla fonte (pietrangeli, 1978). i depositi superficiali che ricoprono il territorio di ocriculum sono prodotto dell’interazione perdurata nel tempo delle acque superficiali e della forza di gravità. lunghi nastri di terrazzi coronano il percorso attuale e storico del fiume di roma, mentre i terrazzi originati dal torrente s. vittore sono, per ovvie ragioni, meno estesi. al contrario, la recente attività erosiva del s. vittore ha portato ad affiorare la coltre alluvionale che il torrente aveva deposto in epoche passate. si possono osservare depositi di spessore decimetrico contenenti resti di manufatti ceramici e laterizi del ii-i sec. a.c. e del i-iv sec. d.c. gli intervalli più antichi sono formati da ciottoli eterometrici non classati e matrice sabbiosa di colore giallo ocra; quelli più recenti sono gradati e costituiti da ciottoli centimetrici arrotondati e orientati, immersi in abbondante matrice limoso-sabbiosa giallastra. depositi sempre prodotti dall’azione delle acque superficiali si rinvengono nella zona del foro, a contatto con il tufo, nei pressi delle piccole sostruzioni. sono sedimenti poco potenti e di ridotta estensione, caratterizzati da conglomerati ben selezionati, formati in prevalenza da ciottoli centimetrici calcarei, silicei, arenacei e vulcanici, con matrice sabbiosa, riferibili all’unità fluviale di “spicciano” del pleistocene sup. (mancini et al., 2001a, b). la deposizione di questi materiali suggerisce la presenza di fasce preferenziali di scorrimento e incanalamento delle acque e di successivo accumulo. tali depositi sono coperti e, talvolta, incisi da materiale più ricco in matrice, costituito da ciottoli simili a quelli del deposito sottostante, anche se di minori dimensioni e dispersi in una matrice limoso-sabbiosa più abbondante a tetto dello strato. nella sezione affiorante immediatamente sopra il fig. 7 successione stratigrafica del territorio di ocriculm (da: mancini et al., 2001a, b, modif.). stratigraphic sequence of ocriculum area (modif. by mancini et al., 2001 a, b). m. bertacchini & l. cenciaioli tratto di basolato (fig. 8) si osserva una successione di diversi episodi di dilavamento formati da strati di spessore decimetrico di sabbie grossolane e ciottoli centimetrici, contenenti resti di vita quotidiana del i-ii sec. d.c. al loro interno è possibile rinvenire resti di manufatti di piccole e medie dimensioni, frammenti di ossa animali (cervi, cinghiali, ecc.) e frustoli carboniosi prodotti delle attività antropiche, oltre a frammenti di ostree, a segnalare apporti da sedimenti marini. la sezione, che nel tratto esposto ha uno spessore complessivo di circa un metro, presenta alla base due intervalli decimetrici: quello inferiore contiene frammenti di marmi e di laterizi, quello superiore, di spessore variabile, ingloba frammenti di intonaci, laterizi e vetri del i sec. d.c. gli episodi soprastanti sono gradati con un accenno di orientazione e sono costituiti da ciottoli centimetrici passanti a sabbie grossolane, immersi in una matrice limoso-sabbiosa di color ocra contenente frustoli carboniosi concentrati in letti e frammenti di ossa. tutta l’area archeologica è ricoperta da uno spessore elevato di materiale formato da abbondante matrice, scarso ciottolame e privo di tracce di orientazione. a conferma di ciò, i risultati dei sondaggi commissionati alcuni anni fa dalla soprintendenza per i beni archeologici dell’umbria nell’area delle terme, hanno rilevato uno spessore di diversi metri di detrito sopra le rovine archeologiche, con una profondità di 4-5 m dal p.c. per le fondazioni dell’impianto termale. un altro sondaggio, realizzato alcuni metri sotto la base di queste fondazioni, campionò materiale che per i suoi aspetti litologici fu assimilato a terreno di riporto (dati inediti cenciaioli). i sedimenti che hanno sepolto la città di ocriculum si possono ricondurre a due diverse ipotesi evolutive: possono essere interpretati come deposito colluviale oppure come materiale prodotto da eventi franosi di colata. non è facile stabilire quale di questi due processi abbia prevalso nell’interrimento della città, è più probabile ritenere che si sia verificata un’azione combinata di entrambi i processi. 55.. eevvoolluuzziioonnee rreecceennttee ddeellll’’aarreeaa la notevole quantità di detrito che ha sommerso le rovine archeologiche di ocriculum si suppone sia provenuta da più settori del versante che domina ad oriente la città romana (fig. 9). le aree di svuotamento sono ben visibili sia da fotografie aeree sia da osservazioni sul terreno e, in generale, si presentano come aree concave impostate al contatto tra i sedimenti marini dell’unità delle “argille sabbiose” e quelli dell’unità delle “sabbie siltose e silt”. la scarsa vegetazione che ricopriva a tratti i versanti, in occasione di periodi freddi e piovosi, può avere favorito l’innescarsi di processi di degrado che si possono essere rapidamente evoluti in movimenti franosi, oppure si possono essere sviluppati in tempi più lunghi quando associati alla formazione di depositi colluviali. il deposito colluviale si sarebbe formato durante periodi di intenso ruscellamento superficiale. la conseguente mobilizzazione dei sedimenti incoerenti presenti avrebbe trasformato i versanti in zone di transito di materiale verso l’area pianeggiante, arrivando a coinvolgere ingenti quantità di terreno. il ripetersi di questo processo in più fasi successive può aver causato l’accumulo di una potente coltre detritica nella zona di pianura, dove sorgeva la città romana. viceversa, gli stessi materiali incoerenti o scarsamente cementati a componente sia sedimentaria, sia piroclastica, presenti nel territorio intorno a ocriculum, possono essere stati interessati da fenomeni franosi in concomitanza di intensi eventi meteorici giornalieri, soprattutto se preceduti da prolungati periodi piovosi. in particolare, sul versante a est di ocriculum, tra il pod. s. francesco e la loc. fontana, si individuano alcune possibili zone di innesco di eventi franosi, contornate da nicchie o balze rocciose. l’estensione delle zone di innesco è limitata, ma la discesa del materiale lungo il versante, sfruttando la sua pendenza e, dove presente, la superficie strutturale a franapoggio del tufo, può avere amplificato il fenomeno coinvolgendo gran parte del materiale più disgregato presente sulla superficie. la convergenza delle zone di accumulo di questi movimenti franosi verso la conca della città romana, fornirebbe altresì una valida giustificazione all’elevato spessore di sedimenti che hanno ricoperto il sito archeologico. l’assenza di tracce o elementi morfologici che confermino il fenomeno franoso porta a dubitare di quest’ultima ipotesi; anche se, solitamente, dissesti di questo tipo coinvolgono spessori limitati di terreni molto erodibili che l’azione del tempo può avere cancellato. 213 fig. 8 sezione sopra il tratto basolato della via flaminia. “flaminia basolato” section. different decimetric beds of coarse sand and centimetric beds of fine to medium grained pebbles mixed in a silty-sandy matrix can be observed. these beds are frequently graded with a weak orientation. remains from the 1st and 2nd century a.d. are often found: pieces of glass, marble, bricks, plaster and animal bones, as well as carbonaceous fragments of domestic fires and ostrea fossils. uno sguardo sulla città romana di ocriculum 214 fig. 9 stralcio della carta geologico-geomorfologica del territorio di ocriculum (base topografica fornita per conc. reg. umbria, 11864/’u2001). a particular of the geological-geomorphological map of the ocriculum area (licence from reg. umbria, ref. n. 11864/’u2001). m. bertacchini & l. cenciaioli 66.. ccoonnssiiddeerraazziioonnii ccoonncclluussiivvee la città di ocriculum sorse nel i sec. a.c. in un’area a poche decine di chilometri di distanza da roma, alla quale era collegata attraverso due importanti vie di comunicazione: la via flaminia e il tevere. la città si sviluppò intorno al torrente s. vittore, difesa naturalmente da due contrafforti in tufo sopra e a ridosso dei quali furono costruiti importanti edifici e ville patrizie. in origine l’area doveva presentarsi come una piccola conca moderatamente incisa dal torrente s. vittore; al fine di creare superfici pianeggianti ampie e stabili, i romani si affidarono alla costruzione di terrazzamenti e di notevoli opere murarie, come le sostruzioni. il problema di colmare e livellare la conca fu probabilmente affrontato dai romani con un progetto articolato in più fasi (bertacchini, 2002). in una prima fase fu costruito un muro di sostegno verso valle, intorno a quota 70 m e trasversale al torrente, con lo scopo di portare ad una diversa altezza il livello di riferimento del tevere. conseguentemente il torrente cominciò a divagare e a ristagnare nella zona a monte della briglia e a depositare i sedimenti trasportati, colmando progressivamente la valle (fig. 6a). una volta colmata la conca si rendeva necessario regolarizzare il corso d’acqua per evitare fenomeni di erosione e di alluvionamento e, per questo scopo, fu costruito un secondo muro a monte e canalizzato il torrente (fig. 6b) per una lunghezza di 300 m circa. nell’area otricolana affiora una successione sedimentaria del pliocene sup.-pleistocene inf., medio (mancini et al., 2001a, b) composta da argille, argille sabbiose e sabbie di ambiente marino passanti a conglomerati di ambiente fluviale, a cui si sovrappongono depositi tufacei del pleistocene medio terminale (mancini et al., 2001a, b) legati all’attività del vulcano di vico. lo scarso grado di cementazione che caratterizza tutti questi depositi può aver favorito l’innesco di fenomeni di dissesto in concomitanza di eventi piovosi intensi e/o prolungati. l’area archeologica fu infatti sepolta sotto una spessa coltre di materiale formato da abbondante matrice con ciottoli sparsi e privo di tracce di orientazione, proveniente da diversi settori del versante ad est di ocriculum e riconducibile a due diverse tipologie di processi: a depositi di tipo colluviale o a depositi prodotti da eventi franosi di colata. entrambi i processi hanno contribuito al seppellimento della città romana. è plausibile pensare che l’abbandono di ocriculum sia avvenuto tra la fine del vi e il vii sec. d.c., anche in analogia con altri siti noti in letteratura, proprio in concomitanza con il periodo indicato come minimo climatico dell’alto medioevo (camuffo & enzi, 1994), o anche noto come “piccola età glaciale alto medievale” (ortolani & pagliuca, 2000). le condizioni climatiche frescoumide che interessarono il bacino del mediterraneo provocarono sicuramente un aggravamento delle condizioni di degrado del territorio otricolano, già peraltro provato da uno stato di incuria e abbandono che succedette al declino della civiltà romana. le fonti storiche non riportano dati a conferma di un probabile trasferimento degli abitanti di ocriculum nel paese di monte durante questo periodo di degrado ambientale; ma, successivamente, a partire dal vii sec. d.c., è solo l’abitato di otricoli ad essere citato nei documenti storici mentre termina qualunque tipo di attività umana nell’antica città di ocriculum. rriinnggrraazziiaammeennttii la ricerca esposta in queste pagine è frutto della collaborazione avviata dal compianto prof. paolo fazzini tra il dipartimento di scienze della terra dell’università degli studi di modena e reggio emilia e la soprintendenza per i beni archeologici dell’umbria, in particolare con la dott. a.e. feruglio soprintendente fino al 2000, e con la dott. l. bonomi ponzi, attuale soprintendente reggente. un ringraziamento particolare per gli utili consigli di carattere geologico è rivolto a d. castaldini, d. fontana e m. panizza del dipartimento di scienze della terra dell’università di modena e reggio emilia. rriiffeerriimmeennttii bbiibblliiooggrraaffiiccii ambrosetti p., conti m.a., parisi g., kotsakis t. & nicosia u. (1977) – neotettonica e cicli sedimentari plio-pleistocenici nei dintorni di città della pieve (umbria). boll. soc. geol. it., 9966, 605-635. ambrosetti p., carboni m.g., conti m.a., esu d., girotti o., la monica g.b., landini b. & parisi g. (1987) – il pliocene e il pleistocene inferiore del bacino del fiume tevere nell’umbria meridionale. geogr. fis. dinam. quat., 1100, 10-33. baldi p., decandia f.a., lazzarotto a. & calamai a. (1974) – studio geologico del substrato della copertura vulcanica laziale nella zona dei laghi di bolsena, vico e bracciano. mem. soc. geol. it., 1133, 575-606. bertacchini m. (2002) – a glance at the roman town of ocricolum (central italy). iv reunión nacional de geoarqueologia. almazán, soria – spain, 16-18 settembre 2002, in stampa. bonomi ponzi l. (1995) – l’umbria meridionale dalla protostoria all’alto medioevo. in: viae publicae romanae. provincia di terni, terni, 128 pp. camuffo d. & enzi s. (1994). cambiamenti climatici negli ultimi 2000 anni. il quaternario, 77(1), 257266. cenciaioli l. (2000) – ocriculum. guida ai monumenti della città antica. ministero per i beni e le attività culturali. soprintendenza archeologica per l’umbria. lab. tip. la fratta, umbertide (pg), 47 pp. cenciaioli l. (2001) – il territorio di otricoli tra umbri e sabini. annali della fondazione per il museo “claudio faina”, orvieto, 88, 293-318. cenciaioli l. (2002a) – nuovi scavi a otricoli lungo la via flaminia. conv. forum sempronii e la via flaminia, fossombrone, urbino, 25-27 giugno 1999, 89-101, in stampa. cenciaioli l. (2002b) – ocriculum. in: umbria antica. vie d’acqua e di terra. sopr. beni arch. dell’umbria, elemond s.p.a., città di castello, 45 pp. 215uno sguardo sulla città romana di ocriculum conti m.a., parisi g. & nicosia u. (1983) – un orizzonte ad amphistegina nel pliocene di orvieto e sue implicazioni tettoniche. boll. soc. geol. it., 110022, 113-122. guattani g.a. (1784-1805) – monumenti antichi inediti per l’anno mdcclxxxiv. vol 11, roma. mancini m., girotti o. & cavinato g.p. (2002a) – carta geologica della media valle del tevere (appennino centrale). settore settentrionale. scala1:40000. centro di studio per il quaternario e l’evoluzione ambientale-cnr, autorità di bacino del fiume tevere, dipartimento di scienze della terra, università di roma “la sapienza”. mancini m., girotti o. & cavinato g.p. (2002b) – carta geologica della media valle del tevere (appennino centrale). settore meridionale. scala1:40000. centro di studio per il quaternario e l’evoluzione ambientale-cnr, autorità di bacino del fiume tevere, dipartimento di scienze della terra, università di roma “la sapienza”. martinori e. (1929) – via flaminia studio storico-topografico. stab. tip. regionale, roma, 233 pp. messineo g. (1993) – via flaminia. istituto poligrafico e zecca dello stato, roma, 185 pp. ortolani f. & pagliuca s. (2000) variazioni climatiche del periodo storico e la prevedibilità delle prossime modificazioni ambientali. geoitalia. forum italiano di scienze della terra. fist. 6, dicembre, mediaprint livorno 39-41. papi l. (2001) – analisi delle problematiche e tecniche di recupero per la tutela e conservazione della chiesa tiberina di san vittore in otricoli. d.u. in materiali per la manutenzione del costruito antico e moderno, facoltà di ingegneria, università di perugia, a.a. 2000-2001. tesi di laurea inedita, 141 pp. pietrangeli c. (1978) – otricoli, un lembo di umbria alle porte di roma. roma, 383 pp. questo lavoro, consegnato alla rivista nel febbraio 2003, è stato revisionato e aggiornato grazie ai dati di bibliografia gelogica recente fornita dai referees. m. bertacchini ha curato gli aspetti descrittivi ed evolutivi del territorio insieme alle osservazioni di collegamento ai dati archeologici-bibliografici forniti da l. cenciaioli. imolto materiale proveniente dall’antica città di ocriculum è stato riutilizzato in numerose abitazioni dell’odierna otricoli. passeggiando per le strette vie del centro, in parte lastricate con blocchi di lava leucitica, è possibile osservare case e palazzi, come quello settecentesco dei conti squarti perla, ornati con fregi a girali, architravi e fregi dorici. 216 ms. ricevuto il 27 febbraio 2003 testo definitivo ricevuto il 15 luglio 2003 ms. received: february 27, 2003 final text received: july 15, 2003 m. bertacchini & l. cenciaioli imp. ascione llee vvaarriiaazziioonnii ggeeoommoorrffoollooggiicchhee iinnddoottttee ddaallllaa tteettttoonniiccaa rreecceennttee iinn aappppeennnniinnoo mmeerriiddiioonnaallee aalleessssaannddrraa aasscciioonnee && aallddoo cciinnqquuee dipartimento di scienze della terra, università degli studi di napoli “federico ii”, largo s. marcellino 10, 80138 napoli riassunto accanto agli effetti derivanti dallo scuotimento sismico, le deformazioni tettoniche generano nel paesaggio modificazioni i cui tipi ed entità sono funzione dal rapporto tra i tassi delle deformazioni ed i ritmi dei processi eroso/deposizionali con i quali esse interagiscono. in questo lavoro vengono esaminati i principali tipi di variazioni ambientali causati dalle deformazioni tettoniche tardo-quaternarie in appennino meridionale, una regione nella quale i lineamenti tettonici ad attività recente sono caratterizzati da una debole espressione morfologica. ciò appare rappresentare la risposta ad una tettonica che si manifesta con fagliazioni distribuite su numerosi lineamenti, ciascuno dei quali registra bassi tassi deformativi, cui si oppone una dinamica esogena che, grazie al clima, al giovane rilievo ed all’elevata erodibilità dei terreni occupanti vaste aree, risulta particolarmente vivace. abstract besides the effects resulting from the seismic shaking (landslides, sinking, etc.), active tectonics may affect the environment, on a longer time scale, through changes whose types and magnitudes depend on the relationships between the rates of deformation and the rates of geomorphic processes. type and magnitude of changes will thus vary according to the geomorphic scenario in which deformations take place. in this paper is presented an overview on the changes triggered by recent deformations (e.g. to tectonics active since the late quaternary) in environments characterised by different rates of the erosional/depositional processes. the scenarios examined are river valleys, intramontane basins, coastal plains and slope areas. in the region, the observed environmental changes appear on the whole quite subdued: this is due to the interplay between the low slip rates (on the order of few tenths of mm/yr) of the numerous and widely distributed normal faults active within the present extensional regime, and the high rates of the exogenous processes. the latter are controlled by the aggressive mediterranean climate, by the high relief of the young chain (that formed starting from the miocene) and by the widespread occurrence of highly erodible rocks. in contrast, in the volcanic district of the campania region (which comprises the phlegrean fields, the somma-vesuvius and the neapolitan islands), high rate volcano-tectonic vertical movements triggered strong and rapid environmental changes in the holocene; in the coastal campana plain, these vertical movements were roughly counterbalanced by high rates pyroclastic deposition. parole chiave: geomorfologia, tettonica attiva, variazioni ambientali, quaternario, appennino meridionale. keywords: : geomorphology, active tectonics, environmental change, quaternary, southern apennines. il quaternario italian journal of quaternary sciences 1166(1), 2003, 133-140 pprreemmeessssaa l’appennino meridionale, risultato di una strutturazione molto recente, è interessato da una tettonica ancora attiva che, tra l’altro, si manifesta con un’intensa e frequente sismicità che ha dato luogo anche a devastanti terremoti in epoca storica ed attuale. ciò nonostante, la forte articolazione orografica che caratterizza la regione non appare che localmente (e.g. fianco tirrenico) dominata da forme tettoniche: all’interno della catena, infatti, il rilievo è per buona parte scandito da alti versanti strutturali con varie orientazioni che, tuttavia, sono in maggioranza forme a controllo strutturale passivo quali versanti di linea di faglia. d’altra parte, per quei versanti strutturali che sono legati in modo diretto alla tettonica più recente (scarpate di faglia quaternarie) si hanno oramai sufficienti dati geologici e morfologici per concludere che, nel corso delle ultime centinaia di migliaia di anni, essi hanno registrato ritmi di crescita relativamente blandi (nell’ordine dei decimi di mm/a), derivati da riattivazioni di ordine decimetrico con ricorrenze di ordine millenario (ascione & cinque, 1997). evidenze di un rallentamento dei ritmi medi di deformazione della catena nel corso del tardo quaternario sono anche l’estinzione dei grandi bacini lacustri intracatena (creati e mantenuti attivi dalla tettonica del pleistocene inferiore e medio), nonché le recenti emersioni e progradazioni registrate nelle depressioni peritirreniche, che erano invece state occupate da ampi golfi marini nel precedente intervallo a maggiore ritmo di subsidenza. la scarsa espressione morfologica dei lineamenti tettonici sembra essere la conseguenza sia della recente impostazione del regime tettonico attualmente attivo, sia delle modalità con cui esso si manifesta. tale regime, che è regionalmente caratterizzato da estensione (hippolyte et al., 1994) avente direzione analoga a quella ottenuta dai meccanismi focali dei terremoti del sud italia (cello et al., 1982; gasparini et al., 1985) ed ha seguito la cessazione, avvenuta nel pleistocene medio, dei raccorciamenti sul fronte esterno (patacca & scandone, 1999) e dei ribassamenti distensivi sul fianco tirrenico, si è instaurato infatti solo nel tardo pleistocene medio (caiazzo, 2000; cinque et al., 2000). in esso, inoltre, si registra l’attivazione di numerose faglie distribuite su larga parte della catena, dal margine tirrenico fino all’ex-avanfossa: tra le faglie la cui attività recente è stata riconosciuta, ciascuna appare aver assommato piccoli rigetti, con ritmi medi relativamente bassi, nell’ordine di pochi decimi di mm/a nell’intero intervallo tardopleistocene medio attuale (cinque et al., 2000; ascione et al., 2003). 134 a. ascione & a. cinque ad una tettonica agente con bassi tassi, si oppongono processi eroso/deposizionali che sono particolarmente aggressivi sia perché il rilievo locale nella giovane catena è ancora alto, sia per il contesto climatico regionale, sia, infine, perché larga parte della regione (le aree esterne della catena, l’ex-avanfossa, ma anche vaste porzioni delle zone interne come il promontorio cilentano) è occupata da litotipi ad alta erodibilità. 11 llee mmooddiiffiiccaazziioonnii ccrreeaattee nneell ppaaeessaaggggiioo ddaallllaa tteettttoonniiccaa in uno scenario quale l’appennino meridionale, caratterizzato cioè da una tettonica che agisce con ritmi mediamente molto prossimi (se non, a luoghi, inferiori) a quelli della dinamica esogena, ci si attende che le deformazioni recenti abbiano prodotto solo lievi modificazioni del paesaggio. poiché la velocità del modellamento varia in funzione dei tipi e dei ritmi dei processi eroso/deposizionali agenti che, a loro volta, sono condizionati dall’erodibilità dei litotipi affioranti, gli effetti delle fagliazioni variano al variare (oltre che dei ritmi che le sono propri) dei contesti orografici e litologici in cui si articola una regione. nei contesti conservativi in cui i ritmi della dinamica esogena sono lenti, ad esempio, gli effetti delle crisi deformative vanno sommandosi nel tempo, dando luogo a forme più vistose rispetto a quelle che ci si attende di rinvenire nelle aree in cui i processi eroso/deposizionali si manifestano con maggiore vivacità. al contempo, dove i processi esogeni agiscono con alti tassi, le forme tettoniche riconoscibili saranno solo quelle molto recenti. 1.1 effetti delle fagliazioni in ambienti fluviali le interazioni della tettonica con i processi legati al sistema morfodinamico fluviale danno luogo a diversi tipi di modificazioni nel paesaggio (santangelo, 2003); tra esse le più vistose sono quelle dovute al movimento differenziale di blocchi in senso trasversale rispetto ai tracciati fluviali. nella regione qui presa in esame, esempi di recenti sovralluvionamenti causati da questo tipo di fenomeno si hanno nell’alta valle del volturno (brancaccio et al., 1997) e nella piana di alife, al margine nne della piana del volturno, dove sono riferibili al pleistocene finale olocene (successivi alla deposizione dell’ignimbrite campana; quest’ultima ha età 39 ka; de vivo et al., 2002), ma anche nella porzione settentrionale del bacino dell’alta val d’agri; altri casi si riscontrano nel massiccio del m. marzano, dove sono dovuti all’attività di faglie tra le quali quella che ha prodotto dislocazioni durante il terremoto del 1980 (cinque et al., 1980; westaway & jackson, 1987; pantosti & valensise, 1990: ascione et al., 2003). il tipo di risposta del sistema fluviale a movimenti verticali di blocchi è essenzialmente controllato dal rapporto tra il tasso della tettonica e quello della dissezione fluviale, quest’ultimo dipendente, oltre che dal potere erosivo del corso d’acqua, dall’erodibilià dei terreni costituenti la soglia. la creazione di ambienti con sedimentazione lacustre, infatti, è favorita nei casi in cui la soglia è impostata in litologie resistenti all’erosione: in appennino meridionale, il sollevamento relativo di soglie carbonatiche ha, ad esempio, provocato l’instaurarsi di ambienti lacustri nei bacini di acerno (nel pleistocene medio; munno et al., 2001), camerota (nel pliocene superiore), del vallo di diano (tra il pleistocene medio e l’olocene). più complessa è la risposta dove, nell’area interessata dalle disarticolazioni verticali, sono presenti terreni ad alta erodibilità. questi tipi litologici affiorano largamente nella regione, dove sono dati dalla gran parte delle successioni terrigene costituenti le coperture flyschoidi e le falde interne liguridi e sicilidi (tutti occupanti vaste aree, ad es., del promontorio cilentano e della fascia esterna della catena), ma anche le successioni argilloso-sabbioso-conglomeratiche prevalentemente plio-quaternarie che costituiscono il riempimento di bacini satellite (diffuse soprattutto nella fascia esterna della catena), nonché della vasta avanfossa bradanica, oltre ai depositi alluvionali quaternari (fig. 1). da quanto si osserva, nelle aree in cui sono stati creati depocentri a tergo di strutture in sollevamento impostate in terreni ad alta erodibilità, i tassi della dissezione hanno mediamente bilanciato quelli della tettonica. ad esempio, nei bacini della bassa valle del tanagro (pleistocene medio; amato et al ., 1991), della valle del melandro (pleistocene inferiore, santangelo, 1991) e dell’alta val d’agri (di niro et al., 1992), che sono chiusi da soglie in rocce tenere, la sedimentazione è caratterizzata prevalentemente da facies fluviali, cui si intercalano limitati intervalli pelitici a testimoniare solo brevi periodi di ostruzione del drenaggio. si può poi osservare che, in questi casi, lo spessore del pacco sedimentario non rappresenta che un’approssimazione per difetto dell’entità di sollevamento relativo della soglia, che veniva interessata da contemporanea dissezione. nelle aree occupate da rocce tenere, la presenza di tratti sovralluvionati costituisce spesso la più evidente, se non l’unica, traccia della disarticolazione del tracciato longitudinale di valli fluviali. infatti, mentre nelle valli chiuse da soglie in rocce resistenti l’aggradazione a monte di un alto in sollevamento è accompagnata dalla nascita di una forra ripida attraverso la soglia, ma anche, se il sollevamento è dovuto all’attività di una faglia, dalla nascita di una ripida scarpata lungo il lineamento (vedi gli esempi citati del vallo di diano, di camerota, di acerno), questi caratteri morfologici possono mancare nel caso di soglie “tenere”. ciò è quanto si osserva, ad esempio, nella bassa valle del tanagro, dove i fianchi vallivi nel blocco sollevato, come pure la scarpata di faglia, mostrano un profilo non sensibilmente diverso rispetto a quelli dei tratti contigui (fig. 2); ciò dipende dal fatto che, con simili terreni, lo slope decline dei versanti vallivi procede tanto rapidamente che, al limite, esso può riuscire a tenere il passo della dissezione. in situazioni di questo tipo, la ricostruzione è confermata dal dato geologico che la base del riempimento alluvionale si pone ben al di sotto (fino a molte decine di metri) della quota del fondovalle nel tratto sollevato. questa conferma diventa decisiva per distinguere i casi di influenza attiva “certa” della tettonica da quelli di controllo passivo esercitato da variazioni litologiche lungo il percorso vallivo, che similmente possono generare tratti stretti senza depositi e tratti più ampi e svasati con fondivalle a copertura alluvionale, che, però, in questi casi è sottile: tali situazioni ricorrono lungo le valli che dissecano la zona esterna della catena, caratterizzata da pieghe e faglie inverse coinvolgenti complessi di erodibilità differenziata. va comunque considerato che, al limite, depocentri potrebbero non nascere anche nel caso di soglie tettoniche impostate in litologie ad erodibilità tanto alta (ad esempio, le argille) da permettere alla dissezione di tenere il passo del tasso di sollevamento. 135le variazioni geomorfologiche ... 1.2 variazioni ambientali legate ai rapporti tra tettonica e sedimentazione nelle depressioni subsidenti, che in appennino meridionale sono date da graben costieri e conche intramontane (fig. 3), l’intergioco tra la dinamica esogena e quella endogena può causare sensibili variazioni ambientali che possono tradursi, nelle aree costiere, in migrazioni della linea di costa e degli ambienti di transizione ed, nelle conche, in modificazioni nei sistemi deposizionali e nell’avvicendamento tra contesti geomorfologico/sedimentari diversi. come esempio, tra le conche intramontane, può citarsi quello del vallo di diano, una depressione tettonica con versanti più attivi lungo il suo margine orientale, in cui si è registrato nel corso del pleistocene medio un sostenuto ritmo dei ribassamenti (intorno a 0.7 mm/a; karner et al., 1999). lo spazio creato dalla notevole mobilità della faglia bordiera è stato accomodato, oltre che dall’aggradazione lacustre, da quella di numerosi apparati di conoide provenienti dallo stesso versante, i cui depositi erano tuttavia confinati presso quello stesso margine. a partire dal tardo pleistocene medio, il ritmo medio dei ribassamenti è andato attenuandosi (esso è valutabile in circa 0.2 mm/a nel pleistocene superiore olocene) fino a divenire inferiore a quello della sedimentazione. ciò ha comportato la vistosa progradazione di ampi sistemi di conoide alimentati dai rilievi orientali sulle facies lacustri che sono state confinate, riducendosi in ampiezza, verso l’opposto margine della depressione (fig. 4) ed, infine, il progressivo colmamento del bacino che, in epoca storica, veniva occupato da un’ampia palude fino alla definitiva bonifica. in questa stessa conca, una possibile recente ripresa della tettonica è suggerita dall’impaludamento che rese necessario, in epoca borbonica, riprendere la bonifica già realizzata in epoca romana allorquando, tra l’altro, si provvide ad approfondire la forra che attraversa la soglia calcarea che richiude la conca verso nord. in altri casi osservati, la recente progradazione fig. 1 schema strutturale dell’appennino meridionale. modificato da modello strutturale d’italia (scandone et al., 1983). structural sketch map of the southern apennines. modified after structural model of italy (scandone et al., 1983). fig. 2 una faglia con componente verticale del rigetto crea un ostacolo attraverso un tracciato fluviale in un’area occupata da rocce altamente erodibili. questo fenomeno può essere denunciato solo dalla presenza, a monte dell’ostacolo, di un tratto sovralluvionato in cui la base dell’accumulo si spinge al di sotto di quella del fondovalle nella forra: il rapido addolcimento dei neogenerati fianchi della forra e scarpata di faglia, infatti, fa si che questi non appaiono più “freschi” rispetto ai più antichi versanti del tratto a monte. a: block diagram illustrating a normal component fault cutting across a valley which dissects highly erodible rocks; b: plan view of the same area. in such cases, the antecedence may be revealed only by the presence of a thick mantle of alluvial deposits whose base is found at an elevation lower than the elevation of the bottom of the neighbouring, downvalley gorge. other expected morphological parameters, such as steep newly generated gorge flanks and a steep fault scarp, are not found due to the slope decline that may proceed fast enough to keep peace with both the river downcutting and the fault slip. 136 degli apparati di conoide disposti lungo fronti montuosi bordati da faglia, come quelli della piana di alife, o alcuni tra quelli del bacino del pantano di s. gregorio magno, costituisce un effetto dello slittamento dell’area di massima deposizione degli stessi conoidi verso la zona centrale del bacino, indotto dal fatto che la faglia si muove con un tasso inferiore a quello della sedimentazione del conoide. in questi casi, fagliazioni recenti hanno interessato gli stessi apparati di conoide, provocando il sollevamento relativo, con conseguente dissezione, della loro porzione apicale e la formazione di nuovi conoidi incastrati nei precedenti ed aventi un’area depocentrale più avanzata rispetto ai primi (fig. 5). nei graben costieri presenti lungo il margine tirrenico della campania, che erano stati sede di considerevoli ribassamenti nel corso del pleistocene (fino ad oltre 3000 m nella piana campana, circa 2000 m nella piana del sele e circa 800 m in quella del garigliano; ippolito et al., 1973; brancaccio et al., 1991), i mutamenti nel rapporto tra il ritmo della sedimentazione e della tettonica occorsi dal tardo-pleistocene – olocene hanno provocato considerevoli variazioni ambientali. in particolare, la cessazione dei ribassamenti ed il sollevamento post-tirreniano di una vasta porzione della piana del sele hanno favorito la progradazione della fascia costiera a partire dalla fine della risalita post-glaciale. nella piana del volturno, che era stata ingredita fino ai rilievi carbonatici bordieri nell’ultimo interglaciale (romano et al., 1994), la sostanziale cessazione della subsidenza e la cospicua aggradazione sedimentaria e vulcanoclastica hanno permesso, nel corso dell’ultimo glaciale e dell’olocene, una progradazione della piana di circa 20 km (barra et al., 1996). nella porzione meridionale della piana campana, la piana del sarno, la presenza di precisi marker, quali livelli torbosi datati, depositi dell’eruzione vesuviana del 79 d.c. e le tracce di linea di riva romana, ha consentito di ricostruire importanti variazioni ambientali occorse nella seconda parte dell’olocene. in tale periodo, nonostante la notevole fig. 3 le depressioni peritirreniche e le principali conche intramontane dell’appennino meridionale. con il rigato verticale, le aree che sono state in aggradazione fino al pleistocene medio p.p.; con il rigato orizzontale, le aree ancora in aggradazione nell’olocene. the peri-tyrrhenian grabens and the main intramontane tectonic depressions of the southern apennines. the vertical lines indicate the areas which have been subject to aggradation until the middle pleistocene p.p.; the horizontal lines mark the areas affected by aggradation in the holocene. fig. 4 evoluzione del vallo di diano durante la parte bassa del pleistocene medio (aa) e nel tardo pleistocene medio olocene (bb). aa: gli alti tassi di scorrimento del lineamento bordiero orientale vengono in parte compensati da aggradazione lacustre e dei conoidi; la sedimentazione di questi ultimi è confinata al margine attivo dove viene continuamente creato spazio. (bb) il tasso di subsidenza è divenuto inferiore a quello della sedimentazione dei conoidi che possono progradare, confinando la sedimentazione lacustre all’opposto margine della conca. evolution of the vallo di diano basin during the lower part of the middle pleistocene (aa) and from the late part of the middle pleistocene to the holocene (bb). aa: high slip rates of the master fault that borders the graben towards the e are compensated by sedimentation of lacustrine and alluvial fan deposits; due to the high subsidence rate, fan deposition is confined to the active margin of the basin. (bb) a decrease in the subsidence rate with respect to the sedimentation rate of the alluvial fans allows progradation of the latter and consequent narrowing of the area occupied by lacustrine sedimentation, which is now confined to the opposite side of the basin. a. ascione & a. cinque 137 subsidenza (media di 1.8 mm/a nel corso degli ultimi 5000 anni; circa 2 mm/a dal 79 d.c. ad oggi) si registra una progradazione della piana di circa 3 km per i notevoli ritmi di aggradazione causati dagli apporti piroclastici del somma-vesuvio (cinque, 1991). va tuttavia precisato che la progradazione della piana del sarno è avvenuta per impulsi, stasi e temporanee inversioni di tendenza, verosimilmente sotto il controllo di interazioni tra moti verticali, fluttuazioni eustatiche minori e variazioni dei ritmi di apporto sedimentario: ad esempio, alla progradazione occorsa nel primo millennio d.c. fece seguito, in epoca medioevale, un arretramento che riportò ambienti di transizione sulla linea di riva di epoca romana (albore livadie et al., 1989). 1.3 effetti delle fagliazioni sul rilievo gli effetti più diretti e localizzati delle fagliazioni, come la creazione di scarpate e dislivelli regionali, sono stati diversi a seconda dei diversi scenari geomorfologici ricorrenti nella regione. negli ambienti favorevoli alla crescita di falde detritiche e/o colluvionali alla base dei versanti di faglia, ad esempio, la presenza e l’altezza di una scarpata denunciante i rigiochi più recenti della faglia sono condizionate dal rapporto tra il tasso di scorrimento della faglia e la velocità dell’accumulo. in appennino meridionale, l’attività tettonica recente dei lineamenti basali di versanti di faglia quaternari risulta spesso priva di conseguenze topografiche (le scarpatine sono modeste rispetto ai movimenti occorsi) perché i rigetti sono stati mascherati dalla crescita di una falda detritica al piede del versante. dove la mancanza di ripiani stabili e/o la natura più fine dei prodotti di alterazione (o degli output clastici) impedisce o quasi l’ispessirsi di falde al piede dei pendii, i rigiochi più recenti della faglia generatrice si manifestano con scarpatine basali (ovvero poste al limite superiore del tratto con copertura detritica) le cui altezza e pendenza sono proporzionali alla resistenza all’erosione dei litotipi affioranti (fig. 6a). nella regione, casi di maggiore espressione morfologica dei rigetti “recenti” si hanno lungo versanti impostati sui calcari di piattaforma carbonatica e sulle successioni silico-carbonatiche bacinali. essi, di norma, consistono in liscioni poco degradati, di altezza non superiore ad alcuni metri, che cumulano gli effetti di eventi di scorrimento risalenti almeno alla fine dell’ultimo glaciale: esempi se ne rinvengono all’interno del massiccio del m. marzano, ma anche al monte s. giacomo e lungo qualche scarpata di faglia tra quelle che bordano le conche tettono-carsiche di s. gregorio magno e buccino, dove corrono al contatto tra i calcari e i depositi di versante. all’estremo opposto si collocano i casi dei versanti impostati su litologie di alta erodibilità quali, ad esempio, i terreni della coltre sicilide e le porzioni argillose delle successioni dell’avanfossa, dove sono estremamente rari i casi di profili di versante con elementi ripidi basali. ciò suggerisce che, su tali litologie, i tempi necessari alla regolarizzazione del profilo dopo che esso è stato spezzato da un rigetto (tipicamente di ordine decimetrico) sono mediamente inferiori ai periodi di inattività che separano gli eventi di scorrimento delle faglie. questi, per quanto emerge dagli studi paleosismologici condotti negli ultimi anni in appennino meridionale, nel tardo quaternario sono stati di ordine millenario (pantosti & valensise, 1990; pantosti et al., 1993a; 1993b; vittori et al., 1995). ovviamente, nei casi in cui il rapido seppellimento o la rapida erosione dei gradini via via creati dalla faglia consentono il mantenimento di un profilo di versante regolare, all’assenza o labilità di conseguenze topografiche in prossimità della faglia fa riscontro, ad una scala più ampia, il progressivo incremento di altezza del versante, con conseguente rinvigorimento dell’erosione nell’ambito del blocco sollevato (fig. 7a; fig. 8). anche nel caso dei versanti di faglia che bordano aree in aggradazione, quali conche intramontane e graben peritirrenici, l’attività tettonica recente molto spesso non da luogo a manifestazioni topografiche lungo i lineamenti, sebbene ad una scala maggiore essa determini il perpetuarsi dell’aggradazione. infatti, molti dei fig. 5 la risposta dei sistemi di conoide a cessazione della fagliazione (aa) e a disgiunzioni con ritmi bassi rispetto a quelli della sedimentazione (bb). aa) in seguito alla cessazione delle dislocazioni, il conoide (la cui sedimentazione era precedentemente confinata all’area prossima alla faglia) inizia a progradare; parallelamente, l’apice del conoide può incunearsi nella valle determinando, come ulteriore effetto, l’aumento di sinuosità del piede del versante. bb) l’apice di un conoide può incunearsi nella valle anche se la faglia basale è attiva, purché il tasso medio di scorrimento di quest’ultima sia inferiore al tasso di sedimentazione; in questo caso, la sedimentazione al piede del versante seppellisce il nucleo roccioso e le fagliazioni interessano il corpo del conoide: ciò provoca erosione in apice e, ancora, progradazione, ma questa volta causata dall’avanzamento del depocentro del conoide. the response of alluvial fans to ceasing of faulting (aa) and to faulting with rates lower than the rates of deposition (bb). aa) the ceasing of faulting allows progradation of the alluvial fan (formerly, aggradation of the fan prevailed over its progradation due to the high subsidence) and also indentation of the fan apex within the valley, with consequent increase of the sinuosity of the mountain front. bb) the apex of a fan may indent within a valley also if the deposition rate overcomes the average slip rate; in this case, the bedrock fault mirror is buried and faulting propagates upwards to displace the alluvial fan: this triggers both downcutting in the apex and progradation of the fan, which is now due to shifting of the depocentre towards the basin axis. le variazioni geomorfologiche ... 138 versanti bordieri di aree in subsidenza e aggradazione mostrano profili dolci che si sviluppano grazie al fatto che la rapida sedimentazione non consente al gradino tettonico di creare una scarpata basale e, pertanto, di interrompere l’evoluzione del versante. ciò è quanto si osserva, ad esempio, per i versanti che bordano la piana campana, e per quelle, tra le scarpate di faglia delle conche tettono-carsiche di s. gregorio mango e buccino, che bordano le porzioni centrali dei due bacini, a maggiore tasso di sedimentazione. in questi stessi ambienti, invece, si rinvengono scarpate nell’ambito delle coperture, dove sono dovute alla propagazione in superficie delle stesse faglie su cui sono impostati i versanti (fig. 6b). infine, si può osservare che negli scenari in cui l’aggradazione tiene il passo delle disgiunzioni, il rilievo locale può non subire sostanziali variazioni nonostante il perdurare dell’attività tettonica (fig. 7b). 22 ccoonnssiiddeerraazziioonnii ccoonncclluussiivvee pur manifestando solo localmente un paesaggio a forte impronta neotettonica (graben peritirrenici; aree con vulcano-tettonica), l’appennino meridionale è un’area nella quale la tettonica ancora in corso, di tipo estensionale e fragile, è comunque in grado di interferire con le dinamiche esogene e apportare modificazioni al paesaggio. in termini di pericolosità ambientale, la tettonica attiva si esprime innanzitutto con scuotimenti sismici e, talora, con l’avvio di crisi di franosità, oltre che con possibili riflessi sull’attività vulcanica, come nel caso delle eruzioni ignimbritiche che hanno accompagnato alcune fasi di collasso nella piana campana. per quanto concerne le conseguenze di ordine geomorfologico trattate in questa nota, è il caso di fare alcune considerazioni sulla entità dei fenomeni e la loro probabilità di accadimento, pur coi limiti imposti dal fatto che si dispone di dati analitici ancora poco numerosi, che non campionano con adeguata fittezza la complessa regione qui presa in esame e che sono spesso caratterizzati da ampi margini di incertezza. a tal fine va innanzitutto considerato il fatto che la fagliazione superfig. 6 effetti morfologici delle fagliazioni su versanti in rocce resistenti senza accumulo basale (aa) e bordanti piane sede di aggradazione (bb). aa) le disgiunzioni modificano il profilo del versante creando un elemento ripido basale. bb) le disgiunzioni hanno effetto in superficie creando scarpate nella sola copertura, mentre l’addolcimento erosionale del versante non subisce interruzioni. the response to faulting of the profile of resistant bedrock fault scarps in various geomorphological scenarios. (aa) where debris accumulation is impeded, the faulting affects the slope profile by creating a steep basal cliff. (bb) if the fault scarp borders a subsiding depressions where aggradation takes place, faulting affects the surface through creation of scarps (generally multiple) in alluvium; in these cases, the slip events do not modify the bedrock slope profile. fig. 7 aa) anche se il gradino tettonico creato dalla faglia alla base del versante è rapidamente mascherato dall’accumulo di una falda detritica, il rilievo locale risulta comunque incrementato sia per aumento dell’altezza della scarpata (da h1 ad h2), sia per l’approfondimento regressivo dei corsi d’acqua (il profilo longitudinale dei corsi d’acqua passa da f1 ad f2). bb) se l’aggradazione riesce a compensare il tasso di scorrimento della faglia, il gradino che nasce lungo la faglia può venire rapidamente mascherato ed il rilievo locale può anche non aumentare; se poi il tasso di sedimentazione supera quello di scorrimento della faglia, il rilievo locale può addirittura diminuire per aggradazione nei fondivalle (da f1 ad f2). aa) even though the slope deposits cover the newborn scarplet hiding the local effect of the faulting, the increase in the scarp height (from h1 to h2) and the consequent regressive deepening of rivers (long rivers profile change from f1 to f2) result in an increase in the local relief. bb) if aggradation equates the slip rate of the fault, the tectonic scarp can be rapidly buried and the local relief may not be increased; furthermore, if the sedimentation rate is larger than the slip rate, the local relief may decrease in response to valley floor aggradation (long rivers profile change from f1 to f2). a. ascione & a. cinque ficiale nella quale si esprime l’attuale regime estensionale si distribuisce su un numero elevato di lineamenti ad attività diacrona, per cui ciascun lineamento registra eventi di scorrimento separati da intervalli di inattività piuttosto lunghi. i singoli eventi di scorrimento (slip event) non sono superiori ad alcuni decimetri e, sulla stessa faglia, essi ricorrono con intervalli di ordine millenario. tralasciando le ben note conseguenze di ordine ingegneristico (danneggiamenti a edifici e infrastrutture) a vantaggio di quelle di ordine geomorfologico (variazioni ambientali), va osservato che eventi dislocativi della entità sopracitata hanno -nel breve termine e in un’ottica antropocentricaconseguenze morfodinamiche trascurabili se vanno ad interessare versanti ed aree interfluviali. i moti verticali associati ai singoli slip event, sebbene di ordine al più decimetrico, possono invece determinare conseguenze sensibili se vanno ad interessare aree costiere a bassa elevazione e gradiente (sommersione e impaludamenti a seguito di ribassamento), oppure fondivalle fluviali a basso gradiente (allagamento o impaludamento di tratti basculati verso monte o posti a monte di settori in relativo sollevamento). sebbene per la regione in esame siano note, anche per tempi storici, sia eventi di istantanea fagliazione superficiale (legate a crisi sismiche particolarmente intense, come quella del 1980) che rapide variazioni ambientali del tipo appena descritto, non sono noti casi di sicura e diretta relazione causa-effetto tra le due tipologie di fenomeni. tale mancato riscontro è, almeno in parte, imputabile al fatto che entrambi i “cataloghi” sono incompleti e soprattutto che non è stata ancora effettuata una approfondita ed estesa ricerca (geologico-geomorfologica, ma anche archivistica e storico-geografica) capace di riconoscere le eventuali concomitanze tra eventi tettonici e geomorfologici. un discorso a parte meritano le aree vulcaniche (vulcani continentali ed insulari dell’area campana) in quanto esse sono state, e possono essere, affette da moti verticali e fagliazioni decisamente più rapide di quelle imputabili a tettonica regionale. vistosi esempi di grandi modifiche del paesaggio, anche in epoca storica, sono offerti dall’area flegrea e dall’isola di ischia: in quest’ultima, linee di riva di età romana si rinvengono a + 25 m (cinque et al., 1997), mentre nell’area del golfo di pozzuoli il terrazzo marino de la starza, emerso dal mare intorno a 5000 anni fa, è stato sollevato sino a circa 60 m di quota e reca scarpate di faglia alte anche alcune decine di metri (cinque et al., 1985). nella stessa area, tracce della linea di riva di epoca romana imperiale si rinvengono fino a – 10 m e quelle di epoca medioevale intorno a – 5 m (cinque et al., 1997); analogamente, a collassi di ordine vulcano-tettonico potrebbe ascriversi anche il ribassamento di circa 4 m manifestato dalla linea di riva romana decorrente sulle pendici sud-occidentali del vesuvio (siti archeologici di ercolano e pompei; cinque & russo, 1986). llaavvoorrii cciittaattii albore livadie c., barra d., bonaduce g., brancaccio l., cinque a., ortolani f., pagliuca s. & russo f. (1989) evoluzione geomorfologica, neotettonica e vulcanica della pianura costiera del fiume sarno (campania) in relazione agli insediamenti anteriori all’eruzione del 79 d.c.. vulcan. paleog. archeol., pact, 1100. amato a., ascione a., cinque a. & lama a. (1991) morfoevoluzione, sedimentazione e tettonica recente dell'alta piana del sele e delle sue valli tributarie. geogr. fis. e dinam. quat., 1144, 5-16. ascione a. & cinque a. (1997) le scarpate su faglia dell’appennino meridionale: genesi, età e significato tettonico. il quaternario, 1100, no. 2, 285-292. ascione a., cinque a., improta l. & villani f. (2003) late quaternary faulting within the southern apennines seismic belt: new data from mt. marzano area (southern italy) . quaternary international, 110011--110022, 27-41. 139 fig. 8 effetti delle fagliazioni sul rilievo a diverse scale, in aree oggetto di erosione con alti ritmi. nel riquadro, da 1 a 3, la nascita e cancellazione del gradino creato da uno scatto della faglia attiva. sebbene i gradini via via creati vengano cancellati, il cumularsi delle disgiunzioni provoca un aumento del rilievo a più ampio raggio (da h1 ad h2); la naturale tendenza all’approfondimento del reticolo nel blocco relativamente sollevato può fornire un ulteriore contributo all’aumento del rilievo locale (cf. profili topografici aa e bb). the response of the landscape to faulting on various scales, in areas subject to erosion with high rates. in the little frame, from 1 to 3, the formation and cancellation of a scarplet due to a faulting event. notwithstanding the cancellation of the single steps, the summation of slip leads to an increase in the relief on a wide range (from h1 to h2); a further contribution to the increase in the local relief is offered by rivers downcutting (see profiles aa to bb). le variazioni geomorfologiche ... barra d., romano p., santo a., campajola l., roca v. & tuniz c. (1996) the versilian transgression in the volturno river plain (campania, southern italy): palaeoenvironmental history and chronological data. il quaternario, 99, no. 2, 445-458. brancaccio l., cinque a., di crescenzo g., santangelo n. & scarciglia f. (1997) alcune osservazioni sulla tettonica quaternaria nell’alta valle del f. volturno. il quaternario, 1100, no. 2, 321-328. brancaccio l., cinque a., romano p., rosskopf c., russo f., santangelo n. & santo a. (1991) geomorphology and neotectonic evolution of a sector of the tyrrhenian flank of the southern apennines (region of naples, italy). zeit. geomorph., suppl. -bd. 8822, 47-58. caiazzo c. (2000) l’evoluzione tettonica del margine tirrenico dell’appennino campano-lucano; ricostruzione dei paleostress e analisi morfostrutturale. tesi di dottorato. università degli studi di napoli “federico ii”. cello g., guerra i., tortorici l. turco e. & scarpa r. (1982) geometry of the neotectonic stress field in southern italy: geological and seismological evidence. j. struct. geol., 44, 385-393. cinque a. (1991) la trasgressione versiliana nella piana del sarno (campania). geogr. fis. e dinam. quat., 1144, no. 1, 63-71. cinque a., ascione a. & caiazzo c. (2000) distribuzione spazio-temporale e caratterizzazione della fagliazione quaternaria in appennino meridionale. in f.galadini, c. meletti, a. rebez (eds.) “ricerche del gndt nel campo della pericolosità sismica (1996-1999)”. cnr-gndt spec. publ., 203-218, roma. cinque a., aucelli p.p.c., brancaccio l., mele r., milia a., robustelli g., romano p., russo f., santangelo n. & sgambati d. (1997) volcanism, tectonics and recent geomorphological change in the bay of napoli. i.a.g. iv int. conf. on geomorphology, geogr. fis. din. quat., suppl. iiiiiit.2, 123-141. cinque a., rolandi g. & zamparelli v. (1985) l’estensione dei depositi marini olocenici nei campi flegrei in relazione alla vulcano-tettonica. boll. soc. geol. it., 110044, 327-348. cinque a. & russo f. (1986) la linea di costa del 79 d.c. fra oplonti e stabiae nel quadro della evoluzione olocenica della piana del sarno (campania). boll. soc. geol. it., 110055, 111-121. d’addezio g., pantosti d. & valensise g. (1991) paleoearthquakes along the irpinia fault at pantano di san gregorio magno (southern italy). il quaternario, 44, no. 1a, 121-136. de vivo b., rolandi g., gans p.b., calvert a., bohrson w.a., spera f.j., belkin h.e. (2002) new constraints on the pyroclastic eruptive history of the campanian volcanic plain (italy). mineralogy and petrology, 7733, 47-65 gasparini c., iannaccone g. & scarpa r. (1985) faultplane solution and seismicity of the italian peninsula. tectonophysics, 111177, 59-78. hippolyte j.c., angelier j. & roure f. (1994) a major geodynamic change revealed by quaternary stress patterns in the southern apennines (italy). tectonophysics, 223300, 199-210. karner d., russo ermolli e., juvigné e., bernasconi s., brancaccio l., cinque a., lirer l., ozer a. & santangelo n. (1999) a middle pleistocene tephrostratotype: the vallo di diano (campania, italy). global and planet. change, 2211, 1-15. ippolito f., ortolani f. & russo m. (1973) struttura marginale tirrenica dell’appennino campano: reinterpretazione di dati di antiche ricerche di idrocarburi. mem. soc. geol. it., 1122, 227-250. munno r., petrosino p., romano p. & russo ermolli e. (2001) a late middle pleistocene climatic cycle in southern italy inferred from pollen analysis and tephrostratigraphy of the acerno lacustrine succession. géographie physique et quaternarie, 5555, no. 1, 1-37. pantosti d., d’addezio g. & cinti f. (1993a) paleoseismological evidence of repeated large earthquakes along the 1980 irpinia earthquake fault. ann. geofis., 3366, no. 1, 321-330 pantosti d., schwartz d.p. & valensise g. (1993b) paleoseismology along the 1980 surface rupture of the irpinia fault: implications for earthquake recurrence in southern apennines, italy. jour. of geophys. res., 9988, no. b4, 6561-6577. pantosti d. & valensise g. (1990) faulting mechanisms and complexity of the november 23, 1980, campania lucania earthquake, inferred from surface observations. jour. of geophys. res., 9955, no. b10, 15.319-15.341. patacca e. & scandone p. (1999) late thrust propagation and sedimentary response in the thrust belt – foredeep system of the southern apennines (pliocene – pleistocene). in g.b. vai & i.p. martini (eds) – anatomy of a mountain system: the apennines and the adjacent mediterranean basin. chapman & hall publ. 1999. in stampa. romano p., santo a. & voltaggio m. (1994) l’evoluzione geomorfologica della piana del fiume volturno (campania) durante il tardo quaternario (pleistocene medio-superiore olocene). il quaternario, 77, no.1, 41-56. santangelo n. (1991) evoluzione stratigrafica, geomorfologia e neotettonica di alcuni bacini lacustri del confine campano lucano (italia meridionale). tesi di dottorato, università degli studi di napoli “federico ii”. santangelo n. (2003) interazione tra tettonica recente e processi geomorfici. questo volume. scandone p. (ed.) (1983) structural model of italy. sottoprogetto “modello strutturale tridimensionale” in f. barberi (ed.) “progetto finalizzato geodinamica”, c.n.r.. vittori e., ferreli l., michetti a.m. & serva l. (1995) holocene paleo-earthquakes along the pollino fault zone (northern calabria, italy): implications for seismic hazard assessment. 5th int. conf. on seismic zonation, nice oct. 17-19, 1995, 14001407. ovest editions, presses académiques. westway r. & jackson j.a. (1987) the earthquake of 1980 november 23 in campania-basilicata (southern italy). jour. of struct. volcanol. & geotherm., 4488, 127-137. 140 ms. ricevuto il 7 gennaio 2003 testo definitivo ricevuto il 1° luglio 2003 ms. received: january 7, 2003 final text received: july 1, 2003 a. ascione & a. cinque imp.bonfiglio bbiioo--cchhrroonnoollooggyy ooff pplleeiissttoocceennee vveerrtteebbrraattee ffaauunnaass ooff ssiicciillyy aanndd ccoorrrreellaattiioonn ooff vveerrtteebbrraattee bbeeaarriinngg ddeeppoossiittss wwiitthh mmaarriinnee ddeeppoossiittss llaauurraa bboonnffiigglliioo11,, cciipprriiaannoo ddii mmaaggggiioo22,, aannttoonneellllaa cciinnzziiaa mmaarrrraa11,, ffeeddeerriiccoo mmaassiinnii22 && ddaarriiaa ppeettrruussoo22 1dipartimento di scienze della terra università degli studi di messina, via sperone 31casella postale 54 98166 messina e-mail: lbonfiglio@unime.it 2dipartimento di geologia e geodesia, università degli studi di palermo, c.so tukory 131, 90134 palermo abstract the rich pleistocene fossil record of sicily allowed the construction of a fairly detailed bio-chronological frame that is dated by correlation of vertebrate bearing deposits with marine deposits by geochemical and radiometric dating too. actually, an important category of deposits is representative of transitional and neritic environments, frequently associated with a lagoon or swamp. limnic deposits related to small freshwater basins also occur, often in relation to coastal and fully marine deposits. numerous relationships have been found between the vertebrate bearing deposits and marine deposits, which can be correlated with the δ18o isotopic record and the main palaeogeographic events in sicily. at present five faunal complexes (f. c.), characterised by the occurrence of different taxa, have been recognised. the two older faunal complexes (monte pellegrino f.c., elephas falconeri f. c.) include taxa with differently marked endemic features. where correlated with marine sediments, the assemblages of the elephas falconeri f. c. are associated with deposits dated early middle pleistocene (comiso, spinagallo cave, san vito lo capo peninsula). in the younger f.c’xes (elephas mnaidriensis f.c., s. teodoro cave-pianetti f.c., and castello f. c.) faunal composition is becoming more similar to that of the southern italian peninsula and denotes that temporary connections with southern italy occurred. where correlated with sediment of marine environments, the assemblages of the e. mnaidriensis faunal complex are associated with deposits dated as late middle pleistocene and/or late pleistocene (s.ciro cave, maddalena peninsula, contrada cacaladritta, cape peloro, contrada fusco, coste di gigia, scodonì, san vito lo capo peninsula). the most likely time interval for the two faunal complex seems to be, respectively, from stage 22 to younger not defined oscillations of the oxygen isotope curve (elephas falconeri f.c.) and from early stage 6 to early stage 4 of δ18o isotopic record (elephas mnaidriensis f. c.). riassunto la ricca documentazione di vertebrati pleistocenici della sicilia ha permesso la costruzione di una dettagliata scala bio–cronologica, datata mediante correlazioni tra i depositi a vertebrati e depositi marini e mediante datazioni geochimiche e radiometriche. i depositi a vertebrati oltre che in ambiente di grotta, sono contenuti in depositi di ambiente neritico e di transizione, spesso associati ad ambienti palustri e/o salmastri. frequentemente i resti di vertebrati sono contenuti in depositi limnici relativi ad ambienti di piana costiera a loro volta correlati con depositi francamente marini. sono stati rinvenuti numerosi rapporti tra depositi a vertebrati e depositi marini correlabili con la curva degli isotopi stabili dell’ossigeno (δ18o) e con i maggiori eventi paleogeografici pleistocenici dell’isola. sono stati riconosciuti cinque complesi faunistici (c.f.) caratterizzati da differenti associazioni faunistiche. i due complessi faunistici più antichi (c. f. di monte pellegrino e c. f. a elephas falconeri), includono taxa a endemismo di entità differente. i depositi contenenti le associazioni faunistiche del c. f. a elephas falconeri sono correlabili a depositi marini della base del pleistocene medio (comiso, grotta di spinagallo, penisola di san vito lo capo). nei complessi faunistici più recenti (c. f. a elephas mnaidriensis, c. f. grotta di s. teodoropianetti e c. f. di castello) la composizione delle associazioni faunistiche diventa sempre più simile a quella dell’italia peninsulare e indica l’esistenza di connessioni temporanee con l’italia meridionale. i depositi a vertebrati del c. f. a e. mnaidriensis sono correlabili con depositi marini del tardo pleistocene medio e/o del pleistocene superiore (grotta di s.ciro, penisola della maddalena, contrada cacaladritta, capo peloro, contrada fusco, coste di gigia, scodonì, penisola di san vito lo capo). l’età più probabile per i due complessi faunistici risulta compresa, rispettivamente, dallo stadio 22 a una oscillazione più giovane, attualmente non definibile della curva degli isotopi stabili dell’ossigeno (δ18o ) (c. f. a elephas falconeri) e dall’inizio dello stadio 6 all’inizio dello stadio 4 della curva isotopica (c. f. a elephas mnaidriensis). keywords: pleistocene vertebrates, quaternary, sicily. parole chiave: vertebrati pleistocenici, quaternario, sicilia. il quaternario italian journal of quaternary sciences 1166(1bis), 2003, 107-114 11.. iinnttrroodduuccttiioonn up to 1985 most of the known pleistocene vertebrate remains of sicily came from cave deposits and little was known about the palaeoenvironmental conditions of the vertebrate-bearing deposits. chronological arrangements of the various pleistocene mammal assemblages of sicily were based on the assumption of the phyletic derivation of the dwarf elephant elephas falconeri from the middle sized elephas mnaidriensis, which was in turn considered a direct descendant of elephas antiquus (accordi, 1963; accordi, 1965; accordi & colacicchi, 1962; ambrosetti et al., 1980). vaufrey (1929) was inclined to assume a post-tyrrhenian age for all the vertebrate faunas. since the studies of accordi (1957; 1963; 1965) it was thought that most of the size reduction of elephants in sicily took place during the period preceding the tyrrhenian. the smallest species (elephas falconeri) was considered to be limited to the early würm period and to have evolved as a consequence of environmental stress linked to the würmian climatic cooling (ambrosetti, 1968; kotsakis, 1979). nevertheless, scinà (1831), vaufrey (1929), accordi & colacicchi (1962) and accordi (1963; 1965) 108 l. bonfiglio et al. provide interesting observations concerning the relationship between vertebrate-bearing deposits and littoral marine deposits. since 1985, a new synthesis has incorporated new stratigraphic and aminostratigraphic data (belluomini & bada, 1985; bada et al., 1991; burgio & cani, 1988; bonfiglio, 1987; bonfiglio, 1992 a; bonfiglio, 1992 b; bonfiglio & burgio, 1992; bonfiglio & insacco, 1992). taphonomic data show that pleistocene vertebrates were distributed in both cave environments and broad, open environments (bonfiglio, 1987;1992 a; 1992 b; 1995; bonfiglio et al., 1996; chilardi & gilotti, 1996a) and numerous relationships have been found between the vertebrate bearing deposits and terraced marine deposits, which can be correlated with the δ18o isotopic record and the main palaeogeographic events in sicily (agnesi et al., 1997; bonfiglio, 1991; bonfiglio et al., 2000; bonfiglio et al., 2002; di maggio et al., 1999). new data concern essentially the number and composition of the pleistocene faunal complexes and stratigraphical, environmental, taphonomic, chronological and palaeogeobiographical characters of the vertebrate-bearing deposits. 22.. ffaauunnaall ccoommpplleexxeess aanndd ppaallaaeeooggeeooggrraapphhyy the pleistocene vertebrate assemblages of sicily can be arranged into 5 phases or faunal complexes (f.c.), spanning from the early pleistocene to the late glacial (bonfiglio et al., 2000; bonfiglio et al., 2001; bonfiglio et al., 2002). the oldest quaternary faunal complex (monte pellegrino f. c.) is documented only in the very restricted geographic area of monte pellegrino, close to the town of palermo, where fossils are contained in small residual deposits of karst fissure. according to burgio & fiore (1997) the poorly diversified fauna is late villafranchian in age. the composition of the monte pellegrino fauna unique for the mediterranean islands suggests it may have been derived in part from an older, not locally known, population phase (messinian age ? azzaroli, 1974; azzaroli & guazzone, 1979) and partially from younger dispersals from europe. the different degree of endemism and the different geographical affinity of the taxa, indicate a polyphasic origin (masini et al. in press). the younger elephas falconeri faunal complex is even poorer than the preceding one in mammalian biodiversity. the poorly diversified fauna includes, besides the pigmy elephant, members of the genera crocidura, lutra, leithia, maltamys, a giant tortoise, and a rich typical endemic avifauna (pavia, 1999; pavia, 2000). neither the ancestor nor the geographic provenance of e. falconeri has been determined unequivocally and its possible origin from european elephas antiquus stock, or from a north african species is still a matter of discussion (bonfiglio & piperno, 1996). moreover, the composition of this faunal complex also reveals a polyphasic origin; some taxa are relics from the preceding phase and others are ‘newcomers’ that probably entered the island through a strongly filtering barrier (masini et al., in press). the subsequent elephas mnaidriensis faunal complex is almost completely renewed in respect to the preceding f. c. the pigmy e. falconeri is extinct, while the faunal composition is more balanced and includes top predators such as the lion and the spotted ‘cave’ hyena. the herbivores (bison, auroch, fallow deer, red deer, hippo) are moderately modified in respect to the congeneric or conspecific taxa from the italian mainland and the endemic nature of the fauna is apparent mainly from the modest reduction in size (abbazzi et al, 2001; bonfiglio et al., 2002). the small mammals, are represented by survivors from the e. falconeri f. c. (leithia, maltamys and crocidura esuae; kotsakis, 1996b, di maggio et al., 1999, petruso, 2001; petruso, in progress; masini et al., in press). one endemic species of bird, cygnus falconeri occurs, while the endemic species of the previous f. c. became extinct, except grus melitensis whose persistence is, however, questionable (pavia, 2000; 2001). amino-acid racemization dating yielded an age of 455 ± 90 ky for elephas falconeri from the spinagallo and luparello cave deposits while an age of 200 ± 40ky has been assigned to the elephas mnaidriensis f. c. by bada et al. (1991). esr dating for teeth enamel of elephas mnaidriensis and hippopotamus pentlandi from contrada fusco (rhodes, 1996) provided an age ranging between 146.8 ± 28.7 and 88.2 ± 19.5 ky. the fourth pleistocene faunal complex (san teodoro cave pianetti f. c.) dates to the last glacial cycle. the faunal history of this period is characterised by extinction events (hippopotamus, endemic dormice and crocidura esuae), and by the dispersal of equids (equus hydruntinus) and of mainland small mammals, which are represented by taxa still occurring in sicily (microtus (terricola) ex gr. savii, crocidura cf. sicula, apodemus cf. sylvaticus, erinaceus europaeus) (bonfiglio et al 1997; bonfiglio et al. 2001, petruso, in progress). almost all of the large mammals belonging to this f. c. seem to be inherited from elephas mnaidriensis f. c.. endemic species of avifauna are lacking (pavia, 2000). finally, the late glacial assemblages of the castello faunal complex show a dramatic decrease in diversity, missing all endemic large mammals still occurring in the s. teodoro cave-pianetti f. c. late glacial faunas, which are similar to continental ones, are associated to lithic artifacts and cultural evidences of late upper palaeolithic (kotsakis, 1979; bonfiglio & piperno, 1996). from the oldest to the youngest, the sicilian faunal complexes show a decreasing degree of endemism and a composition more and more similar to that of the southern italian peninsula . the geographic and stratigraphic distribution greatly varies in space and time (younger sites are much more numerous). such distribution pattern is typical in regions in which tectonic activity is very intense and is probably due to the different extension in time of the emerged areas, which implies sharp lateral variations of the depositional environments. the active extensional tectonic regime affecting sicily from the early pleistocene onwards resulted in the collapse of peripheral zones and lead to the creation of a series of deep marine basins which occupied large areas around and between two emerged blocks (north and south eastern areas, respectively). these two islands were of small extension as well as the related depositional environments. in fact, the number of the deposits containing the two oldest faunal complexes (m. pellegrino and elephas falconeri f.c.), which are early and early-middle pleistocene in age, is very low. conversely, the vertebrate bearing deposits of the latemiddle and early-late pleistocene assemblages (elephas mnaidriensis faunal complex) are very numerous, are contained in deposits of different environments and have a wide distribution all over the island (bonfiglio et al., 2002 with bibliography). from the beginning of the middle pleistocene onwards the evolution of sicily was characterised by a generalised uplift which led to the emersion of the previous deep marine basins and the island reached almost the present extension, being also bordered by a crown of coastal plains. for that reason, a large amount of the mammalian fossils of the elephas mnaidriensis f.c. are from upraised remnants of coastal plains as well as from caves and fissures. during the late pleistocene a strong uplift accompanied by the contemporaneous sea water low-standing led to the disappearance of humid environments of coastal plains. as a matter of fact the deposits of the youngest faunal complex (“s. teodoro cave-pianetti” and “castello” f. c.) are numerous, but they are limited to caves and fissures. the faunal composition of this complex is consistent with the disappearance of humid environments (coastal plains with lagoons or swamps) and the laying down of dry conditions. 33.. ccoorrrreellaattiioonn ooff ffaauunnaall ccoommpplleexxeess wwiitthh mmaarriinnee sseeddiimmeennttss most of the mammalian fossils of sicily are found in caves and fissures rather common in the carbonate mountain ranges of northern sicily and in the hyblean plateau. another important category of deposits is representative of transitional and neritic environments, frequently associated with a lagoon or swamp. limnic deposits related to small freshwater basins also occur, often in relation to coastal and fully marine deposits (fig. 1). the assemblages of the monte pellegrino f.c. and those of s. teodoro cave pianetti and castello 109bio-chronology of pleistocene vertebrate faunas ... f.c.’xes are contained in caves and fissure-filling deposits and they have no relationship with marine deposits. the assemblages of the elephas falconeri and of the elephas mnaidriensis f.c. ’xes are contained in cave deposits correlated with marine deposits, as well as in coastal plain and/or in marine littoral deposits (littoral marine sands, deltaic marine clay sands, deltaic marine gravels and sands) and in continental deposits overlying abrasion platforms. in the different environments the biodiversity, the preservation conditions and the concentration of the skeletal remains are very diverse. 33..11 eelleepphhaass ffaallccoonneerrii ff..cc.. aasssseemmbbllaaggeess ccoorrrreellaatteedd wwiitthh mmaarriinnee sseeddiimmeennttss at comiso a regressive marine sequence begins with early pleistocene marine deposits and ends at the top with sands of brackish environment which, in turn, pass to deposits of limnic environment underlying middle pleistocene marine sands (conti et al., 1980; carbone et al., 1982). in the different levels of the limnic deposits skeletal elements of elephas falconeri, leithia melitensis, bats, fishes, birds, reptiles (lacerta sp., testudo sp., emys orbicularis, geochelone sp.) are contained (bonfiglio & insacco, 1992). the continental limnic succession at comiso, made up by palaesols, lacustrine and aeolian deposits, constitutes the evidence of the first connection of the hyblean plateau to the sicilian mainland in the pleistocene. this connection occurred after the deposition all around the plateau of the plio-pleistocene marine deposits, which end with clays and sands of the latest early pleistocene (di geronimo et al., 1979; conti et al. 1980). the limnic deposits contain the first occurrence of the elephas falconeri faunal complex (bonfiglio & insacco, 1992). the terrestrial gastropods from the limnical deposits of comiso, indicating wet and cool environment, were attributed by esu & girotti (1991) to the earliest middle pleistocene. at spinagallo cave, the lower vertebrate deposits containing abundant remains of elephas falconeri associated with leithia melitensis, maltamys gr. gollcheriwiedincitensis, crocidura esuae, testudo hermanni overlie early middle pleistocene littoral calcarenites (accordi & colacicchi, 1962; petronio, 1970; kotsakis, 1977; 1986; kotsakis & petronio, 1981; di grande & raimondo, 1984; bonfiglio, 1992 b; petruso, in progress). the limnical deposits at comiso may correspond to the beginning of the "roman regression" (ruggieri et al., 1975) that roughly correlates with stage 22 of δ18o isotopic record, while the e. falconeri bearing deposits at spinagallo cave may correspond to younger oscillations of the oxygen isotope curve. at san vito lo capo peninsula several littoral and continental mammal bearing deposits are present and related to a well preserved marine terrace sequence early to late pleistocene in age. the terrace succession, composed of seven orders of abrasion surfaces, has been studied in detail by some authors (antonioli et al., 1998a, b; di maggio et al., 1999) that proposed a correlation with ios succession. di maggio et al. (1999) analysed the vertebrate deposits and their stratigraphic relationships to such terrace sequence. from the middle to the late pleistocene a tectonic activity affected the fig. 1 location of the vertebrate-bearing deposits correlated with marine deposits in sicily quoted in the text. 110 area moderately dislocating the ancient shorelines. mammal remains of the elephas falconeri f. c. have been found in morphological traps (caves and wave cut notches) in the piana di sopra area, where the terrace sequence is fairly complete and the ancient shoreline remains are quite well preserved. elephas falconeri and leithia melitensis remains occur in paleosols deposits overlying a coastal conglomerate preserved in an ancient wave cut notch at 45 m a.s.l. (semaforo site). a dental remain of elephas falconeri has been found within a beach conglomerate resting on the floor of a marine cave opened at about 72 m a.s.l in the palaeocliff bordering the southern side of piana di sopra (isolidda 2 site). according to the reconstruction of the palaeogeographic evolution of the area di maggio et al. (1999) referred both mammal deposits to the second order terrace. even though the correlation with the ios record is affected by some uncertainties, this terrace can be confidently related to one of the stages comprised between ios 15 and ios 11. the biocronological events that mark the end of elephas falconeri f. c. are still poorly defined. the extinction of e. falconeri might be the result of predation consequent to the dispersal of the large carnivores of the succeeding elephas mnaidriensis faunal complex. 33..22 eelleepphhaass mmnnaaiiddrriieennssiiss ff..cc.. aasssseemmbbllaaggeess ccoorrrreellaatteedd wwiitthh mmaarriinnee sseeddiimmeennttss the most important recent finding of vertebrate bearing deposits containing faunal remains of the elephas mnaidriensis f.c. is that of contrada fusco, located south to the hill of neapolis, to the west of syracuse, where a very rich faunal assemblage (an elephant of little reduced size, elephas mnaidriensis, hippopotamus pentlandi, ursus cf. arctos, crocuta crocuta spelaea, lutra trinacriae, leithia melitensis, maltamys wiedincitensis, crocidura esuae, emys orbicularis, testudo cfr. hermanni, lacerta siculomelitensis, natrix sp.) comes from a stratigraphic sequence cropping in three low hills (respectively, eastern sector, tor di conte and western sector), separated by fluvial incisions. the coastal plain deposits overlie early pleistocene bathyal clays and underlie tyrrhenian calcarenites (chilardi & gilotti, 1996 a; 1996 b; chilardi, 1996 a; kotsakis, 1996 a; 1996 b; cassoli & tagliacozzo, 1996 a; 1996 b). the stratigraphic section (chilardi & gilotti, 1996 a, fig. 1, p. 26) includes six sedimentary units (l1, all, c3, c4, l2, l3) interbedded between the marine substrate, early pleistocene in age, and overlying littoral calcarenites attributed by di grande & raimondo (1974) to the thyrrhenian. according to chilardi & gilotti (1996 a) the deposition of continental silts (l1), containing scarce vertebrate remains, and fluvial conglomerates (all), containing numerous skeletal elements of large mammals, is followed by a marine ingression, which lead to the deposition of marine biocalcarenites of shallow water environment (c3) eteropic of gravels and sands of back-shore environment (c4). the overlying silts of marsh environments (l2) are attributed to a marine regression to which a successive marine ingression follows, represented by brackish lagoons (l3). however, carefully looking to fig. 1, p. 26 in chilardi & gilotti (1996 a) and to the palaeontological and taphonomical characteristics of the deposits, the six sedimentary units probably represent the different sedimentary facies of a late middle pleistocene coastal plain which gradually became subsiding before the deposition of tyrrhenian calcarenites. at contrada fusco together with the remains of elephas mnaidriensis, remains of a larger elephant (elephas sp.) have been collected (chilardi, 1997) which may represent the first arrival of continental species not yet reduced in size of the elephas mnaidriensis f.c. the “paleosoil” containing remains of elephas mnaidriensis (accordi, 1963; 1965) underlying tyrrhenian calcarenites at maddalena peninsula (castelluccio lighthouse) probably belong to the same coastal plain which extended south of the hill of neapolis. actually several fossil remains have been signalled by de gregorio (1924-25) south of c.da fusco in the the anapo river valley where pleistocene alluvial conglomerates underlie tyrrhenian calcarenites (chilardi, 1996 b). an isolated scapula of elephas mnaidriensis comes from thyrrhenian marine deposits at maddalena peninsula (accordi, 1963). according to di grande & raimondo (1984) the present highest altitude of the thyrrhenian “ calcarenites of targia ” in the area of neapolis-maddalena peninsula is about 25 m. north to contrada fusco, at coste di gigia, the red clays containing hippopotamus pentlandi and elephas mnaidriensis overlie late middle pleistocene littoral gravels and calcarenites and a small wave-cut platform relative to a shore line located at 40 m a.s.l. calcarenites and abrasion platform are cut by the younger tyrrhenian abrasion platform which presents its inner margin at the altitude of 34 m a.s.l. again the faunal assemblage of the elephas mnaidriensis f.c. is late middle pleistocene in age (bonfiglio, 1992 b). the different position of tyrrhenian calcarenites in respect to mammal bearing deposits at coste di gigia and at contrada fusco is due to the location of the two sites in areas with different uplift rate, respectively the priolo depression and the floridia graben (di geronimo et al., 1980; carbone et al., 1982). in the late pleistocene sandy gravel outside the s. ciro cave, the rare hippopotamus and elephant remains (molars, limbs) are disarticulated, encrusted by serpulid polychaetes worms and associated with a rich marine fauna containing gastropods, bivalves, ostracods, foraminifera, of littoral euryhaline environment (galletti & scaletta, 1991). at s. ciro cave the vertebrate assemblage contains abundant remains of hippopotamus pentlandi associated with rare remains of elephas mnaidriensis, cervus siciliae, dama carburangelensis, bos primigenius siciliae, canis lupus, ursus cfr. arctos, crocuta spelaea (scinà, 1831; fabiani, 1928). the marine sands and the wave cut notch with lithodomus holes, brought to light by scinà (1831) at the bottom of the cave deposits, probably have a middle pleistocene age. at contrada cacaladritta rare skeletal remains of hippopotamus pentlandi, elephas cf. mnaidriensis and bos primigenius siciliae are concentrated in deltaic clayey sands with ostrea edulis that underlie gravelly, sandy and calcareous continental deposits with fresh water mollusks. the two units constitute the uppermost middle pleistocene portion of a regressive marine sequence, which begins with early pleistocene clays of bathyal environment (bonfiglio et al., 1996, with bibliol. bonfiglio et al. 111 graphy). disarticulated, fragmented, worn and mechanically selected remains of elephant (elephas mnaidriensis), hippopotamus (hippopotamus pentlandi), red deer (cervus elaphus siciliae), bear (ursus cf. arctos), tortoise (testudo cf. hermanni) are contained in the deltaic marine gravel and sandy deposits underlying thyrrhenian sands with strombus bubonius at cape peloro. serpulids encrust some skeletal elements (bonfiglio & berdar, 1979; bonfiglio & violanti, 1986; marra, 2001). at acquedolci gravels and silty laminated lacustrine deposits overlie a wave-cut platform and beach gravels relative to a shore line located at 130 m a.s.l and contain very abundant skeletal elements of the endemic hippo hippopotamus pentlandi associated with scarce remains of cervus elaphus siciliae, ursus cfr. arctos, canis lupus, elephas mnaidriensis, testudo cfr. hermanni, birds. the vertebrate bearing deposits, the abrasion platform and the beach gravels are in turn cut by the younger tyrrhenian abrasion platform which in this area presents its inner margin at the altitude of 105 m a.s.l. (bonfiglio, 1992 a; bonfiglio, 1995). at scodonì, east to acquedolci, fluvial gravels containing abundant remains of hippopotamus pentlandi associated with scarce remains of ursus cfr. arctos, overlie the large tyrrhenian abrasion platforms extended between 80 and 105 m a.s.l. (bonfiglio, 1987) at san vito lo capo peninsula, eutyrrhenian deposits and/or abrasion platforms are well represented and continuously distributed at a height comprised between 0 and 18 m a.s.l. (sixth order terrace). within such deposits a rich “senegalese” fauna including strombus bubonius and patella ferruginea locally occurs. at seno dell’arena site scant remains of dama carburangelensis are encrusted above the eutyrrhenian abrasion surface at 10 m a.s.l. at caletta cofano remains of elephas mnaidriensis, bos primigenius and crocuta crocuta occur at about 1-2 m a.s.l. within a continental succession composed by paleosol sediments alternated to stone lines overlying marine calcarenites. the abrasion surface, on which the continental deposit lies, is correlated with ios 5a or 5c (di maggio et al., 1999). all these data represent the evidence that the first occurrence of the elephas mnaidriensis f.c. in the island is late middle pleistocene in age and that this elephant survived the eutyrrhenian interglacial. stratigraphical correlations at acquedolci, s. ciro cave, coste di gigia show that the e. mnaidriensis assemblages are found in late middle pleistocene terraced deposits overlying a shoreline which probably corresponds to ios 7 (bonfiglio, 1991). chronostratigraphical data concerning the last occurrences of the taxa of this faunal complex are still poorly defined, but significant evidence come from s. teodoro cave and contrada pianetti. at these sites the highly diversified assemblage of vertebrates (elephant, horse, wild ox, deer, wild boar, hyena, fox, mice, ground vole, shrew, hedgehog, bats, birds, reptiles) invertebrates and vegetal remains lacks hippopotamus, endemic dormice and crocidura esuae. the assemblage of small mammals is completely renewed in respect to that of the e. mnaidriensis faunal complex, and includes not endemic taxa such as microtus (terricola) ex gr. savii, apodemus, erinaceus and crocidura cf. sicula (bonfiglio et al., 1997; bonfiglio et al., 2001). the association of the elephant (elephas mnaidriensis) with the equid (equus hydruntinus), which were previously thought to represent the typical taxa of two different faunal complexes (the endemic elephas mnaidriensis faunal complex and the younger, not endemic, castello faunal complex), evidences a longer survival of the elephant and the associated taxa in sicily. the combined occurrence of taxa up to now considered as typical, or exclusive, of two contiguous faunal complexes (elephas mnaidriensis and castello f.c.’s) can be explained by the occurrence of a dispersal event posterior to ios 5e. geochemical and radiometric dating are not available and the deposits of the large s.teodoro cave are still to be more extensively investigated. the most likely time interval for this faunal complex is from early ios 6 to early ios 4. bio-chronology of pleistocene vertebrate faunas ... fig. 2 – chronological correlation frame of the vertebrate-bearing deposits with marine deposits in sicily (from di maggio et al., modified). 112 44.. ccoonncclluussiioonn in sicily numerous relationships have been found between the faunal assemblages of two faunal complexes (elephas falconeri f.c. and elephas mnaidriensis f. c.) and marine deposits, which can be correlated with the δ18o isotopic record and the main palaeogeographic events in sicily (fig. 2). vertebrate are contained in deposits of transitional and neritic environments, frequently associated with a lagoon or swamp. limnic deposits related to small freshwater basins also occur, often in relation to coastal and fully marine deposits. where correlated with marine sediments, the assemblages of the elephas falconeri f. c. are associated with deposits dated early middle pleistocene (comiso, spinagallo cave, san vito lo capo peninsula) while the assemblages of the e. mnaidriensis faunal complex are associated with deposits dated as late middle pleistocene and/or late pleistocene (acquedolci, s.ciro cave, maddalena peninsula, cape peloro, contrada fusco, coste di gigia, scodonì, san vito lo capo peninsula). the most likely time interval for the two faunal complex seems to be, respectively, from stage 22 to 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(eds.) le ossa dei giganti. lo scavo paleontologico di contrada fusco. siracusa: arnaldo lombardi, 68-72 kotsakis t. and petronio c., 1981 i chirotterri del pleistocene superiore della grotta di spinagallo (siracusa, sicilia). bollettino del servizio geologico d'italia, 110011, 49-76. marra a. c., 2001 resti di vertebrati delle ghiaie pleistoceniche della formazione di messina (sicilia 113bio-chronology of pleistocene vertebrate faunas ... nord-orientale). il naturalista siciliano, s. iv, 2255 (1-2), 3-13. masini f., bonfiglio l, petruso d., marra a.c., f., abbazzi l, torre d., 2000, in press the role of coastal areas in the neogene quaternary mammal island populations of the central mediterranean . biogeographia. pavia m., 1999 the middle-pleistocene avifauna of spinagallo cave (sicily, italy): preliminary report. smithsonian contributions to paleobiology, 8899,, 125-127 pavia m., 2000 le avifaune pleistoceniche dell’italia meridionale. unpublished phd dissertation, university of torino, xiii cycle, 150 pags. pavia m., 2001 middle pleistocene fossil avifauna from the elephas mnaidriensis faunal complex of sicily (italy): preliminary results. the world of elephants, 1st international congress (rome, october 16th20th, 2001), abstract book. petronio, c., 1970 i roditori pleistocenici della grotta di spinagallo (siracusa). geologica romana, 99, 149194. petruso d., 2001 i ghiri della sicilia antica. in sarà m. (ed.) ghiri in sicilia: ecologia e conservazione. wwf, 27-41. petruso d., in progress stratigrafia e paleogeografia del quaternario continentale siciliano: il contributo dei micromammiferi. phd dissertation in geological science, universities of naples and palermo. rhodes e. j., 1996 esr dating of tooth enamel. in basile b. & chilardi s. (eds.), le ossa dei giganti. lo scavo paleontologico di contrada fusco. arnaldo lombardi, siracusa, 39-44. ruggieri g., unti a., unti m., moroni a., 1975 la calcarenite di marsala (pleistocene inferiore) e i terreni contermini. bollettino della società geologica italiana, 9944, 1623-1627. scinà d., 1831 rapporto sulle ossa fossili di maredolce e degli altri contorni di palermo. dalla reale tipografia di guerra, palermo. vaufrey r., 1929 les éléphants nains des iles mediterranèennes et la question des isthmes pléistocènes. archives de l’institut de paléontologie humaine, paris, 66, 1-220. 114 l. bonfiglio et al. impaginatopelfini ii gghhiiaacccciiaaii ddeellllaa vvaall ssiissssoonnee ((vvaalltteelllliinnaa,, aallppii rreettiicchhee)) ee llaa lloorroo ssttoorriiaa oolloocceenniiccaa mm.. ppeellffiinnii,, gg.. ddiioollaaiiuuttii && cc.. ssmmiirraagglliiaa con la collaborazione di l. montrasi dipartimento di scienze della terra, università di milano riassunto – i ghiacciai della val sissone (valtellina, alpi retiche) e la loro storia olocenica. la ricostruzione dell’evoluzione di alcuni ghiacciai della val sissone (alpi retiche), in particolare quello del disgrazia, ha permesso di fornire un contributo alla conoscenza delle fluttuazioni glaciali alpine con particolare riguardo alla piccola età glaciale ed ai periodi più recenti. attraverso l’utilizzo di diversi metodi di datazione (radiocarbonio, dendrogeomorfologia, documentazione storica), la massima espansione olocenica dell’apparato glaciale del disgrazia dovrebbe collocarsi dopo il xiv secolo, con altre espansioni negli anni ’20-‘30 o negli anni ’50 del xix secolo ed infine negli anni ’20 e ’80 del xx secolo. la tendenza del xx secolo, documentata da misure dirette delle variazioni frontali, è stata in ogni caso nettamente negativa e ha portato la fronte del disgrazia ad arretrare di circa 1 km. abstract – the val sissone glaciers (valtellina, rhetian alps) and their holocenic evolution. the reconstruction of the evolution of some val sissone glaciers (rhetian alps, italy), with particular attention to the disgrazia glacier, gives a contribution to the knowledge of the glacial fluctuations since the little ice age in the italian alps. by utilizing different dating methods (radiocarbon, dendrogeomorphology, historical documentation), it is possible to attribute the maximum glacial advance to a period after the xix century. other glacier expansion phases belong to the ’20 yrs of the xix century and to the ’20 and ’80 years of the xx century. the xx century trend, based on terminus variation direct measurements, was in any case absolutely negative and caused a retreat of the disgrazia glacier snout of about 1 km. parole chiave: variazioni glaciali, olocene, piccola età glaciale, datazioni radiometriche, dendrogeomorfologia key-words: glacier variations, holocene, little ice age, radiocarbon dating, dendrogeomorphology il quaternario italian journal of quaternary sciences 1155(1), 2002, 3-9 11.. iinnttrroodduuzziioonnee l’attuale fase di regresso dei ghiacciai alpini è una realtà ormai acquisita, con ritmi che sembrano incrementarsi nel tempo e con modificazioni indotte nel paesaggio di anno in anno sempre più evidenti ed accentuate. la ricostruzione della storia glaciale passata rappresenta un importante contributo alla conoscenza della dinamica ambientale attuale: infatti, solamente attraverso un’accurata ricostruzione delle vicende, antiche e recenti, che hanno caratterizzato l’evoluzione delle masse glaciali alpine, è possibile riconoscere la sincronia degli eventi anche in regioni lontane, comprendere meglio la dinamica delle risposte glaciali alle variazioni climatiche, cogliere le tendenze in atto e, infine, formulare futuri scenari evolutivi. il lavoro qui presentato si propone come un esempio di indagine, realizzata mediante l’integrazione di diverse discipline e metodi di datazione, finalizzata alla ricostruzione della storia glaciale recente di una valle delle alpi lombarde, la val sissone, situata alla testata della valmalenco, tributaria della valtellina (alpi retiche, italia). nel paesaggio glaciale della val sissone spiccano le forme di accumulo glaciale rappresentate da morene che, come per la maggior parte delle vallate alpine, sono morfologicamente ben delineate, scheletriche, con suolo poco evoluto, prive di vegetazione o poco inerbite, disposte in modo quasi concentrico a formare piccoli anfiteatri. queste forme sono il segno lasciato dai ghiacciai alpini, nel corso degli ultimi 150 anni, nell’ambiente d’alta quota, ghiacciai che hanno manifestato in quest’intervallo di tempo un regresso frontale quasi continuo, interrotto da modeste avanzate. la fase di ritiro, tuttora in corso, ha segnato la conclusione della piccola età glaciale (peg), intervallo temporale durante il quale la maggior parte dei ghiacciai alpini ha manifestato la massima avanzata olocenica. 22.. ii gghhiiaacccciiaaii ddeellllaa vvaall ssiissssoonnee la val sissone è ubicata alla testata della valmalenco, nel gruppo del bernina-disgrazia, a n del m. disgrazia (fig. 1). su di essa si affacciano i ghiacciai disgrazia, sissone e vazzeda ed alcuni apparati minori originatisi negli ultimi decenni in seguito al frazionamento di questi ultimi. al culmine della peg, la testata della valle era occupata da un unico grande ghiacciaio avente un’estensione di circa 803.9 ha; successivamente, la massa glaciale si è frazionata in una serie di individui minori che nel 1992 coprivano complessivamente una superficie di 474.28 ha (folladori, 1997) con una diminuzione del 41% circa rispetto all’estensione assunta durante la peg e con un ritiro lineare di oltre un chilometro e mezzo per il solo ghiacciaio del disgrazia. quest’ultimo rappresenta l’apparato glaciale più esteso della zona; si tratta di un ghiacciaio di circo-pendio esposto a nord che occupa una superficie di 335 ha, con lunghezza massima di 2400 m e larghezza pari a 2100 m (servizio glaciologico lombardo, 1992). gli altri corpi glaciali della zona sono tutti apparati di circo di varie dimensioni; i ghiacciai di punta baroni e del passo di chiareggio sono di limitata estensione, rispettivamente di 10 e 23 ha, mentre il ghiacciaio sissone con 80,5 ha di superficie è decisamente più ampio. parzialmente unito al sissone è il ghiacciaio di rosso sud-est, con estensione di 12 ha. completano il quadro del glacialismo locale i ghiacciai cima di rosso est (19 ha) e vazzeda (ubicato nella vicina val muretto). 33.. mmeettooddoo ddii llaavvoorroo e’ stato effettuato sul terreno un rilevamento geomorfologico di dettaglio, affiancato da fotointerpretazione sui fotogrammi 22 e 23 della strisciata 67 (volo del 18-08-1982 dell’aeronautica militare) alla scala 1:30.000 e su alcuni ingrandimenti alla scala 1:5000. tale lavoro ha portato alla realizzazione di una carta geomorfologica alla scala 1:10.000. per gli argini morenici riconosciuti sul terreno e cartografati sono state proposte datazioni basate su dendrocronologia e radiocarbonio (applicato a suoli e resti legnosi sepolti) e sull’analisi di documenti storici, cartografici ed iconografici. per quanto riguarda questi ultimi è appena il caso di ricordare come il loro utilizzo a fini geomorfologici fornisca dati attendibili solo dopo la metà del 1800. decisamente più quantitativi, sebbene nel caso in oggetto utilizzabili con molte cautele, sono i metodi dendrocronologici e radiometrici, sui cui principi e problemi di utilizzazione in campo geomorfologico-glaciale si rimanda alla letteratura (giordano, 1971; fritts, 1976; pelfini, 1987; mortara et al., 1992; schweingruber, 1996; pelfini & orombelli, 1997; pelfini 1999). per quanto riguarda la storia glaciale del xx secolo si sono utilizzati soprattutto i dati delle variazioni frontali rilevati annualmente dagli operatori glaciologici. 44.. llaa ssttoorriiaa ggllaacciiaallee oolloocceenniiccaa ddeellllaa vvaall ssiissssoonnee ssiinnoo aall xxiixx sseeccoolloo la storia glaciale della val sissone è stata studiata analizzando in particolare l’apparato morenico frontale del ghiacciaio del disgrazia (fig. 2), la cui lingua raccoglieva durante la peg e ancora fino al 1910 tutte le masse glaciali provenienti dalla testata della valle. le morene più avanzate deposte da questo apparato glaciale sono situate a circa 1780 m di quota sulla destra idrografica del torrente sissone. si tratta di tre argini latero-frontali ben conservati (1, 2 e 3 in fig. 2); sulla sinistra, correlabile dal punto di vista geometrico con la n. 3, è invece riconoscibile un unico breve argine (4 in fig. 2), che è possibile raccordare con due tronconi (5 e 6) in posizione nettamente laterale. la morena più esterna (n. 1), che testimonia la massima avanzata olocenica, presenta uno spessore modesto (si alza di 2-3 metri rispetto alla topografia circostante) e risulta parzialmente coperta nel suo settore laterale da detrito di versante. durante la fase di deposizione della morena, il ghiacciaio ha sigillato il suolo sottostante; al disotto dell’orizzonte organico sepolto si è conservata una porzione di tronco sepolto da un grosso masso appartenente alla morena frontale più esterna. il peso del masso ha deformato l’intera successione degli strati che tendono ad immergere sotto di esso. la deformazione degli strati documenta come la successione che costituisce la sezione fosse già presente prima della messa in posto della morena. la fig. 3 riporta la sezione e lo schema dei rapporti stratigrafici. la lontananza dal versante e l’ubicazione del masso entro la morena, consentono di escludere la messa in posto del masso da parte di processi di versante. l’età 14c ottenuta presso il “geochron laboratories”, massachusset) (campione 99406295 gx 22254) è risultata pari a 600 ± 75 anni b.p. la data è stata sottoposta a calibrazione mediante il programma oxcal (stuiver & reimer, 1993) e si è ottenuto come intervallo di maggior probabilità il xiv secolo o, al limite, il periodo fra il 1280 e il 1440 (anni calendario). poiché il reperto non è in posizione primaria, la sua età è sicuramente e in ogni caso un termine post quem per la messa in posto della morena; questa è dunque avvenuta in un periodo compreso tra il 12801440 ad e l’età della morena immediatamente più interna (n. 2 in fig. 2). il tempo necessario al seppellimento del reperto ligneo e alla formazione del suolo al di sopra delle sabbie che lo inglobano, induce a ritenere che la fase di recrudescenza climatica che ha determinato l’espansione del ghiacciaio del disgrazia si collochi nella piccola età glaciale, forse in una delle sue fasi più antiche. per la datazione della morena n. 2 e delle altre morene più interne e quindi per la ricostruzione della storia glaciale della peg si è provato ad utilizzare metodi lichenometrici e dendrocronologici. 4 pelfini-diolaiuti-smiraglia fig. 1 localizzazione della val sissone. location of the val sissone nell’intera val sissone è stata effettuata una serie di misure lichenometriche. nonostante la relativa facile reperibilità dei licheni, non sono stati trovati talli cresciuti su superfici di esposizione nota. e’ risultato pertanto impossibile costruire una curva di crescita locale sia per il gruppo rhizocarpon geographicum, sia per l’aspicilia cinerea e utilizzare la lichenometria per datazioni assolute. per la morena n. 3 si è proceduto ad indagini dendrocronologiche. similmente alla morena n. 2, questo argine detritico è ben conservato e si snoda lungo il fianco destro della val sissone. le analisi dendrocronologiche non risolvono tuttavia il problema della sua datazione. le misure effettuate su alcuni larici che crescono sull’area prativa immediatamente a monte della morena indicano che il più vecchio di questi presenta 104 anelli di accrescimento; gli estremi cronologici della carota prelevata sono quindi 1892-1995. aggiungendo a questi gli anni necessari a raggiungere il metro di altezza (altezza a cui vengono prelevati i campioni e pari a circa 15-20 anni di età dell’esemplare) e quelli stimati per la colonizzazione (15-20 anni), la pianta potrebbe presentare circa 140 anelli. ciò potrebbe riportare alla metà del xix secolo (1852). va ricordato che alcuni autori aggiungono anche un numero di anelli maggiore. deline (1999) per esempio, in val veny (ao) aggiunge sino a 65-70 anelli per ottenere l’età minima di messa in posto delle morene. la scelta di aggiungere una quarantina di anelli al massimo deriva dalle esperienze fatte in alcune valli delle alpi centrali, per le quali questo valore sembra più ragionevole. utilizzando i valori più elevati proposti da altri autori, si potrebbe ipotizzare un’avanzata intorno al 1830, mentre mantenendo i valori proposti in questo lavoro l’area sembra essersi deglaciata e resa libera per la colonizzazione vegetale almeno a partire dalla metà del xix secolo. la localizzazione del limite inferiore del ghiacciaio durante l’ultimo secolo della peg è confermata dalle carte topografiche del xix secolo, pur tenendo conto della loro non totale affidabilità (specialmente per quelle della prima metà del secolo). la carta dello stato maggiore austriaco del 1833 alla scala 1:86.400, ad esempio, mostra la fronte del ghiacciaio a circa 18101850 m di quota, poco a monte delle morene sopra descritte. la carta topografica svizzera alla scala 1:100.000 rilevata tra il 1854 e il 1871 colloca la fronte del ghiacciaio ad una quota di circa 1900 m, mentre nel 1890 la carta dell’istituto geografico militare (igm) alla scala 1:50.000, che introduce le curve di livello e per la 5i ghiacciai della val sissone ... fig. 2 le morene della val sissone. i numeri indicano i depositi glaciali descritti nel testo. the val sissone moraines. the glacial deposits described in the text are indicated by numbers. fig. 3 profilo del suolo aperto entro la morena n. 1 di figura 2 a quota 1780 m. dall’alto i livelli rappresentano: 0-8 cm orizzonte organico attuale con superficie a prato; 8-14 cm orizzonte organico nero, a tessitura limosa, ricco di frammenti di legno e radici; 14-18 cm sabbia grigio-bruna media, 18-34 cm sabbia media limosa, di colore bruno con venuta d’acqua, 34-40 cm sabbia contenente il reperto ligneo. soil profile of the n° 1 moraine (fig.2), 1780 m a.s.l. from the top: 0-8 cm, present organic level with meadow; 8-14 cm black organic silt level, with wood and root fragments; 1418 cm grey-brown medium sand; 18-34 cm brown medium sand with silt; 34-40 cm sand with wood fragment.. prima volta le quote delle fronti glaciali, indica la fronte a 1945 m. a partire dalla fine del xix secolo, la ricostruzione della storia glaciale si arricchisce di particolari in quanto sono disponibili testimonianze dirette, cartografia aggiornata e rilevata in modo più preciso, relazioni annuali da parte degli osservatori della commissione glaciologica del club alpino italiano, resoconti di ascensioni alpinistiche, fotografie (quali ad esempio quelle di v. sella relative al ghiacciai del disgrazia e vazzeda dal 1896), tutti documenti che hanno consentito una ricostruzione più precisa della storia glaciale recente di questa valle. le fronti glaciali della val sissone sono state visitate con intenti scientifici per la prima volta alla fine del xix secolo da l. marson, che prosegue le osservazioni della lingua del disgrazia sissone per cinque annate consecutive; poi, dopo un periodo di stasi, i rilievi ricominciano a cura degli operatori del comitato glaciologico italiano e proseguono con qualche lacuna fino ad oggi. nel 1893-95 secondo il racconto di alcuni pastori, citato da marson nella sua relazione sull’osservazione delle fronti glaciali della val sissone compiuta nel 1896 (nell’occasione lo studioso pose presso la fronte i primi segnali di misura), il ghiacciaio si trovava in fase di progresso, tanto da aver reso inaccessibili alcune rupi e prati che si potevano raggiungere fino a pochi anni prima (marson, 1897); non sono state però ritrovate evidenze geomorfologiche di tale fase di progresso. secondo marson (1897), che prosegue le osservazioni glaciologiche fino ai primi anni del 1900, nel 1896 la fronte del disgrazia-sissone giungeva a 1945 m di quota e la lunghezza dell’apparato glaciale, calcolata dal passo di s. martino (oggi chiamato passo di mello) fino alla fronte era di 2359 m. tra il 1896 ed il 1897 lo stesso osservatore misura un arretramento frontale pari a 7,8 m (marson, 1898), mentre dal 1897 al 1898 registra un’avanzata di 3,7 m (marson, 1899). 55.. ssttoorriiaa rreecceennttee ddeell ggllaacciiaalliissmmoo ddeellllaa vvaall ssiissssoonnee ((xxxx sseeccoolloo)) la fonte principale della storia glaciale della val sissone nel xx secolo è rappresentata dalle relazioni annuali degli operatori del cgi, raccolte nei bollettini del comitato glaciologico italiano dal 1913 al 1977 e in geografia fisica e dinamica quaternaria dal 1978 ad oggi. con questo materiale è stato possibile tracciare le curve tempo-distanza delle variazioni frontali dei ghiacciai in oggetto e in particolare di quello del disgrazia, che ben testimonia quantitativamente l’evoluzione nel xx secolo del glacialismo della val sissone (figg. 4 e 5). l’inizio del xx secolo è caratterizzato da un fase di regresso; nel 1907, quando marson ritorna a visitare la valle, la lingua del ghiacciaio è infatti arretrata di 83,35 m rispetto alla posizione registrata nel 1899. dopo marson i rilievi sul ghiacciaio del sissone vengono condotti da d. sangiorgi a partire dal 1910. con la prima relazione (sangiorgi, 1912) l’autore sembra suggerire l’avvenuta separazione tra i due apparati principali; in effetti, a partire da quell’anno la lingua glaciale che percorre la val sissone sarà denominata solo “del disgrazia”. dal 1911 al 1916 le sue relazioni testimoniano un continuo ed intenso ritiro che termina solo nel 1917 con un avanzamento frontale di 22 m (sangiorgi, 1919). da allora inizia un nuovo periodo di progresso frontale, in fase con quanto registrato dalla maggior parte dei ghiacciai alpini per i quali si disponga di dati relativi alle variazioni frontali (vivian, 1975; reynaud, 1983; cerutti, 1995). l’avanzata è rapida e nel 1926 la fronte del ghiacciaio è scesa fino a 1970 m di quota. da quell’anno riprende una tendenza al regresso che porta, nel 1928, il ghiacciaio a ritirarsi di ben 25 m (sangiorgi, 1929). nel 1928 la val sissone ed il ghiacciaio disgrazia vengono visitati e studiati anche da g. nangeroni. da allora continua inesorabile il ritiro e la fronte del ghiacciaio nel 1949 arriva a 2020 m di quota, dopo il distacco di una placca di ghiaccio che porta l’apparato ad isolarsi sopra un gradino roccioso e abbandona a valle la porzione crollata ormai separata dal resto del ghiacciaio, coperta di morenico, a formare un cospicuo lembo di ghiaccio morto. nel settembre 1950 l’alta val sissone viene profondamente modificata da “una grande improvvisa alluvione ed un imponente smottamento di parte della morena laterale sinistra del ghiacciaio disgrazia” (nangeroni, 1951). questi eventi rimodellano intensamente l’area proglaciale e parzialmente 6 pelfini-diolaiuti-smiraglia fig. 4 curva delle variazioni frontali cumulate del ghiacciaio disgrazia dal 1895 al 1999 costruita sulla base dei dati raccolti dagli operatori del comitato glaciologico italiano cumulative frontal variations of disgrazia glacier from 1895 to 1999 by italian glaciological committee data. 7i ghiacciai della val sissone ... fig. 5 a) il ghiacciaio disgrazia in una fotografia dell’inizio del xx secolo di autore sconosciuto; b) lo stesso ghiacciaio nel 1997 in una fotografia di l. montrasi. a) disgrazia glacier xxth century beginning (photograph by unknown author). b) same glacier in 1997 (by l. montrasi photograph). a) b) 8 pelfini-diolaiuti-smiraglia distruggono ed occultano i depositi morenici del fondovalle. le relazioni degli anni successivi descrivono una fronte arroccata su un gradino roccioso in continuo ritiro ed una placca di ghiaccio relitto, in fusione, destinata a scomparire. delle morene della valle non si parla più fino al 1954 quando a. riva, nella sua annuale relazione sottolinea la completa demolizione dell’apparato morenico del vecchio ghiacciaio (riva, 1955). fino al 1957 le osservazioni annuali al ghiacciaio vengono condotte con regolarità ed in quell’anno la fronte della placca di ghiaccio morto viene registrata a 2110 m di quota; poi per più di un ventennio la val sissone viene dimenticata, se si fa eccezione per il rilievo condotto da c. corona nel 1974. negli anni ’80 riprendono le osservazioni e le misurazioni frontali del ghiacciaio disgrazia. l’operatore che lo visita (catasta, 1981) osserva la fronte a 2400 m con il ghiacciaio in fase di netto progresso che sembra unito al ghiacciaio punta baroni che si trova alla sua sinistra. il progresso frontale continua per qualche anno e nel 1981 catasta (1982) rileva che la lingua di sinistra, avanzando verso il fondovalle, sta formando un arco morenico di spinta, mentre la fronte vera e propria, avanzando, è andata unendosi al ghiaccio crollato dalle regioni superiori a formare ghiaccio di rimpasto. nel 1984 la fronte è scesa fino a 2030 m di quota (considerando per fronte la porzione di ghiaccio di rimpasto o rigenerato ormai conglobato con la lingua vera e propria) ed è abbondantemente coperta di materiale morenico grossolano (catasta, 1986). la fase positiva è ancora in atto nel 1988, anche se il progresso non risulta quantificabile, poiché i segnali sono stati spazzati via dall’alluvione che ha colpito la valtellina nel 1987. si tratta dell’ultimo periodo di avanzata glaciale, in fase con quella che ha caratterizzato la maggior parte degli apparati alpini europei ed extraeuropei (wood, 1988; zanon, 1991; cerutti, 1992; pelfini & smiraglia, 1992) in conseguenza della recrudescenza climatica globale nota come “episodio freddo” (pinna, 1996). gli indizi di regresso si manifestano a partire dal 1990 nelle colate laterali, mentre la colata principale, protetta da una spessa coltre di morenico, continua una lieve avanzata. la tendenza al ritiro si afferma negli anni successivi e porta la fronte a retrocedere, fino ad un massiccio distacco di una porzione terminale nel 1995, che lascia una fronte sospesa su ripido pendio roccioso a 2250 m di quota ed una porzione di ghiaccio isolato, “morto”, coperto da morenico nel fondovalle (mariani, 1997). da allora il ghiacciaio ha continuato a ritirarsi per un arretramento lineare valutabile in oltre 450 m che ha portato la fronte sino a quota 2370 m. dinamica glaciale simile ha manifestato nel tempo il ghiacciaio del sissone, monitorato anch’esso a partire dal 1911 da sangiorgi ed attualmente in fase di marcato regresso. 66.. ccoonncclluussiioonnii l’utilizzo di metodologie integrate (rilievi geomorfologici, dendrocronologia, documentazione storica) ha permesso di individuare numerose fasi di espansione olocenica del ghiacciaio del disgrazia e di proporre, seppur con incertezze, alcune date di deposizione delle morene. ad esempio, la massima estensione, testimoniata da evidenti morene frontali, potrebbe non essere stata raggiunta al culmine della peg, che generalmente si colloca intorno al 1820-25 (ad esempio per la mer de glace), bensì dopo il xiv secolo. alle ulteriori fasi di espansione della peg (primi decenni oppure metà del xix secolo), segue una fase di intenso regresso quasi continuo, brevemente interrotto dalle due limitate fasi di avanzata degli anni ’20 e degli anni ’80 del xx secolo. per quanto riguarda quest’ultimo secolo, anche se le morfologie non si sono perfettamente conservate e solo le più recenti sono rimaste a testimonianza della dinamica glaciale, i documenti storici e le misure dirette condotte per oltre cento anni, hanno permesso di ricostruire in misura attendibile la storia glaciale della valle e di verificare che i ghiacciai della val sissone hanno manifestato una risposta all’effetto forzante del clima in fase con altri apparati glaciali alpini. lavoro realizzato nell’ambito del cofinanziamento murst 1999, progetto di ricerca: “ghiacciai alpini e variazioni ambientali”. responsabile nazionale prof. a. biancotti, responsabile locale prof. a. bini. si precisa che il lavoro è stato realizzato e scritto congiuntamente dai tre autori. bbiibblliiooggrraaffiiaa catasta g. (1981) relazione della campagna glaciologica 1980. geogr. fis. dinam. quat., 4 (2) 160-161. catasta g. (1982) relazione della campagna glaciologica 1981. geogr. fis. dinam. quat., 5 (2) 387-389. catasta g. (1986) relazione della campagna glaciologica 1984. geogr. fis. dinam. quat., 9 (1) 25. cerutti a.v. (1992) l’espansione dei ghiacciai del monte bianco fra il 1962 e il 1989. geogr. fis. dinam. quat., 15, 75-84. cerutti a.v. (1995) variazioni dei ghiacciai del monte bianco in epoca storica. in: “archivi glaciali. le variazioni climatiche ed i ghiacciai.” atti dell’incontro di courmayeur, 2-3 settembre 1995, 9-28. corona c. (1974) relazione della campagna glaciologica 1974. boll. com. glac. it., serie ii, 22, 262-263. deline p. (1999) la mise en places de l’amphithèatre morainique du miage (val veny, val d’aoste). geomorphologie. folladori l. (1997) “global change: studio delle variazioni climatiche e ambientali oloceniche nelle alpi lombarde, mediante indagini geomorfologiche e glaciologiche”. in: collana ricerca e risultati, fondazione lombardia per l’ambiente, 30 pp.100123 fritts h.c. (1976) tree rings climate. academy press, london, 567 pp. giordano g. (1971) tecnologia del legno 1° la materia prima. 1986 pp, u.t.e.t., torino. mariani v. (1997) relazione della campagna glaciologica 1996. geogr. fis. dinam. quat., 20 (2), 391-392. 9i ghiacciai della val sissone ... marson l. (1897) sui ghiacciai del massiccio del monte disgrazia o pizzo bello. memorie soc. geogr. it., 7 (1), 63-68. marson l. (1898) sui ghiacciai del massiccio del monte disgrazia e bernina. memorie soc. geogr. it., 8 (2), 168-170. marson l. (1899) sui ghiacciai del massiccio del monte disgrazia e bernina. memorie soc. geogr. it., 9, 170-173. mortara g., orombelli g., pelfini m. & tellini c. (1992) suoli e suoli sepolti olocenici per la datazione di eventi geomorfologici in ambiente alpino: alcuni esempi tratti da indagini preliminari in val d'aosta. ii quaternario 5 (2),135-146. nangeroni g. (1951) la frana di val sissone (15 settembre 1950). natura, 42, 11-17. pelfini m. & orombelli g. (1997) variazioni recenti dell’ambiente alpino registrate nelle serie di anelli di accrescimento delle conifere. applicazioni della dendrogeomorfologia. acqua e aria, 6, 103-110 pelfini m. & smiraglia c. (1992) recent fluctuations of glaciers in valtellina (italian alps) and climatic variations. journ. glac., 38, 309-313. pelfini m. (1987) contributo alla conoscenza delle fluttuazioni oloceniche del ghiacciaio dei forni. natura bresciana ann. mus. civ. sc. nat., brescia, 24, 237-257. pelfini m. (1999) dendrogeomorphological study of glacier fluctuations in the italian alps during the little ice age. annals of glaciology 28, 123 – 128. pinna m. (1996) le variazioni recenti del clima. angeli, milano. reynaud l. (1983) european glaciological data and their relation with the climate . in “new perspectives in climate modelling”, edited by a.l. berger and c. nicolis, elsevier science publishers b.v., amsterdam riva a. (1955) relazione della campagna glaciologica 1954. boll. com. glac. it., serie ii, 6, 188-191. sangiorgi d. (1912) osservazioni sui ghiacciai di valmalenco. rivista cai, 2, 43-45. sangiorgi d. (1919) relazione preliminare sui ghiacciai della valtellina. boll. com. glac. it, 3, 18. sangiorgi d. (1929) relazione della campagna glaciologica 1928. boll. com. glac. it, 9, 276-279. schweingruber f.h. (1996) tree rings and environment dendroecology. haupt verlag. servizio glaciologico lombardo (1992) ghiacciai in lombardia. edizioni bolis, bergamo. stuiver m. & reimer p.j. (1993) radiocarbon, 35, 215230. vivian r. (1975) les glaciers des alpes occidentales. grenoble, allier wood f. (1988) global alpine glacier trends 1960s to 1980s. arct. alp. res., 20, 4, 404-413. zanon g. (1991) vent’anni di progresso dei ghiacciai 1965-1985. atti del convegno “le variazioni climatiche recenti (1800-1990) e le prospettive per il xxi secolo”, roma, 5-6 aprile 1990, mem. soc. geogr. it., 46, 153-165. ms. ricevuto il 28 dicembre 2000 testo definitivo ricevuto il 24 luglio 2001 ms. received: december 28, 2000 final text received: july 24, 2001 imp.farabollini& i travertini dell’ italia centrale adriatica: genesi, cronologia, significato geomorfologico e paleoambientale farabollini piero1, materazzi marco1, miccadei enrico2 & piacentini tommaso2 1dipartimento di scienze della terra, università degli studi di camerino piero.farabollini@unicam.it 2dipartimento di scienze della terra, università degli studi “g. d’annunzio” di chieti miccadei@unich.it riassunto: farabollini p., materazzi m., miccadei e. & piacentini t., i travertini dell’italia centrale adriatica: genesi, cronologia e significato geomorfologico e paleoambientale. it issn 0394-3356, 2004. nella parte adriatica dell’italia centrale depositi travertinosi sono presenti in alcuni affioramenti principali e in una serie di affioramenti minori, distribuiti essenzialmente lungo il fronte della catena appenninica calcarea e in corrispondenza della sua fascia pedemontana. gli affioramenti principali, in particolare, sono distribuiti a diverse quote, da circa 150 m a oltre 900 m s.l.m.; essi inoltre sono disposti, in generale, in appoggio su un substrato calcareo o terrigeno miocenico-pliocenico o sui depositi pliocenico-quaternari, ed in differente correlazione con i depositi continentali quaternari che caratterizzano le valli di alcuni dei principali corsi d’acqua del versante adriatico (fiume esino, fiume potenza, fiume chienti, fiume tronto, fiume pescara, fiume salinello, fiume alento e fiume foro). quasi tutti gli affioramenti studiati evidenziano la presenza di una placca travertinosa in discordanza stratigrafica con il substrato o in successione su depositi prevalentemente grossolani di origine fluviale alternati a facies fluviali di minor spessore caratterizzate da stratificazione piano -parallela ed incrociata, gradazioni, ecc. i depositi di travertino, in particolare, sono caratterizzati da travertini fitoermali talvolta alternati a sabbie e ghiaie calcaree fitoclastiche, ad indicare la presenza di ambienti deposizionali ad “alta energia” localmente associati ad ambienti di acque “calme” generalmente di tipo palustre-lacustre. per quanto riguarda la cronologia dei depositi, di cui alcuni oggetto di recenti datazioni, essi indicano età a partire dal pleistocene superiore all’olocene antico (sefro, pioraco, serrapetrona); altri depositi, invece, la cui datazione è stata basata su correlazioni con altri depositi continentali quaternari, sono attribuibili al pleistocene medio (montepiano e civitella del tronto). tutte le aree analizzate, pur presentando depositi di estensione e spessore differenti, nonché diverse caratteristiche idrochimiche delle acque circolanti, mostrano tuttavia lineamenti comuni, molto significativi al fine della ricostruzione dei meccanismi e degli ambienti deposizionali e del contesto climatico. caratteristica comune a tutti i depositi infatti è la messa in posto in ambiente tipicamente fluviale, sia per la loro disposizione (perlopiù simmetrica e parallela all’asse fluviale), sia per la presenza spesso di strutture tipiche da trasporto che per gli stretti rapporti con i depositi alluvionali presenti lungo l’alveo. nel presente lavoro, oltre a descrivere le caratteristiche deposizionali dei diversi depositi travertinosi presenti nell’area adriatica, e la loro collocazione cronologica, viene proposta una classificazione che, differentemente da quelle esistenti in letteratura, tiene conto di ambienti deposizionali e condizioni morfologiche particolari e più o meno localizzate. abstract: farabollini p., materazzi m., miccadei e. & piacentini t., the travertines of the adriatic central italy: genesis, chronology and geomorphological and palaeoenvironmental significance. it issn 0394-3356, 2004. in the adriatic side of central italy, travertines are present in few main and in several minor deposits, mainly distributed along the calcareous apennine chain and the piedmont belt. main deposits are located at different heights, from about 150 m up to 900 m a.s.l. they usually overlie calcareous or miocene-pliocene terrigenous bedrock or alternatively pliocene-quaternary deposits and are differently related with quaternary continental deposits, characterizing the main river valleys of the adriatic side of central italy (esino, potenza, chienti, tronto, pescara, salinello, alento and foro rivers). almost all deposits are constituted by a travertine plate discordant with bedrock or in succession with coarse fluvial deposits alternating with minor planar or through cross bedded facies, etc.. travertine bodies are constituted by groups of lithofacies, evidencing different depositional mechanisms and environments; phytohermal facies, sometimes intercalated by phytoclastic gravels and sands, progressively changing valley-ward and upward, testify high energy environments locally alternated to low energy ones. concerning the chronology of deposits (some of these recently dated), they indicate age starting from upper pleistocene up to early holocene (sefro, pioraco, serrapetrona); other deposits, whose age is asumed on relationship with other quaternary continental deposits, are attributed to middle pleistocene (montepiano and civitella del tronto). all sites, even though showing deposits with different extension and thickness and different hydrochemical characteristics of circulating waters, have very significant common features, to reconstruct climatic context and depositional mechanisms and environment: typical fluvial environment, symmetric location with respect to river axis, presence of typical structures and close relationships with alluvial deposits. the present work, together with the description of chronology and main depositional mechanisms of the above deposits, also propose a new classification that, differently from other classifications in literature, also consider depositional environments with different, and more or less localized, morphological conditions. parole chiave: deposizione travertinosa, italia centrale adriatica; quaternario. keywords: travertine deposition; adriatic side of central italy; quaternary. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 259-272 260 p. farabollini et al. 1. introduzione il problema della deposizione travertinosa nel versante adriatico dell’italia centrale è stata affrontata da numerosi autori (boni & colacicchi, 1966; cipriani et al., 1977; cilla et al., 1994; calderoni et al., 1996a e b; materazzi, 1996; carrara, 1998; dramis et al., 1999; lombardo et al., 2001; farabollini et al., 2003) ed altrettanto numerosi sono i lavori, a carattere generale, che tentano di classificare i vari depositi sulla base delle loro caratteristiche litologiche e tessiturali (buccino et al., 1978; c h a f e t z & f o l k , 1984; f e r r e r i , 1985; d’argenio & ferreri, 1986; pedley, 1990; d’argenio & ferreri, 1992; golubic et al., 1993; pentecost & viles, 1994; pentecost, 1995; violante et al., 1994; 1996). tali classificazioni tuttavia non sono sempre funzionali alla descrizione dei depositi riconosciuti nell’area umbromarchigiano-abruzzese. i travertini sono sistemi carbonatici la cui deposizione si verifica in ambiente continentale e risulta controllata dall’interazione tra fattori fisici, chimici e biologici e modificazioni ambientali a seguito della loro deposizione (violante et al., 1994). essi sono edifici complessi e comprendono una grande varietà di forme associate spesso alla presenza, attiva o passiva, di organismi diversi, come batteri, alghe, muschi, o resti vegetali (chafetz & folk, 1984 e relativa bibliografia; golubic et al., 1993 e relativa bibliografia). studi microstrutturali hanno evidenziato che i processi di incrostazione sono prevalentemente controllati da alghe (es: oocardium stratum) e cianobatteri (es: phormidium incrustatum) in analogia con quanto riportati da diversi autori per diverse aree studiate (chafetz & folk, 1984 e relativa bibliografia; golubic et al., 1993 e relativa bibliografia; materazzi 1996 e relativa bibliografia). di seguito si riporta una tabella riassuntiva degli organismi che esercitano un controllo primario sulla deposizione dei travertini (tab. 1) distinguendo le specie che rivestono effettivamente un ruolo attivo nei processi di precipitazione (sottolineate in tab. 1) da quelle che fungono solamente da “impalcature”; sono inoltre evidenziate le specie individuate nelle aree di studio (asterischi in tab. 1, su sfondo grigio quelle più frequenti). il presente lavoro si basa sull’analisi e il confronto, condotti mediante rilevamenti geomorfologici e analisi di dettaglio, delle caratteristiche deposizionali e geomorfologiche dei travertini dell’area marchigiano-abruzzese, inquadrando, ove possibile, la loro collocazione cronologica. si propone in particolare un tentativo di classificazione dei travertini che si differenzia da quelli presenti in letteratura tenendo conto di ambienti deposizionali e condizioni morfologiche particolari, facendo riferimento alle situazioni più significative individuate nell’area. 2. caratteristiche geologiche e geomorfologiche l’area esaminata è delimitata ad occidente dalla catena appenninica, ad oriente dall’area costiera adriatica, a nord e a sud rispettivamente dal fiume esino e dal fiume pescara (fig. 1). sulla base delle caratteristiche fisiografiche, geomorfologiche e strutturali, si possono distinguere due settori diversi: la catena appenninica (in particolare la sua porzione più orientale) e la fascia pedemontana, fino a ridosso dell’area costiera. l’area di catena è caratterizzata da una serie di dorsali montuose allineate in direzione da nwse a ns con sommità sempre superiori a 2000 m, in terreni essenzialmente calcarei, calcareo-marnosi e marnosi, giurassico-paleogenici. le dorsali sono interrotte da profonde valli trasversali solcate dai principali corsi d’acqua (f. potenza, f. chienti, f. tronto, f. salinello, f. pescara). l’assetto strutturale è costituito da sovrascorrimenti a vergenza e e ne che determinano la sovrapposizione di litotipi di natura calcarea su litotipi arenaceo-argillosi (parotto & praturlon, 1975; deiana & pialli, 1992; ghisetti et al., 1994; d’alessandro et al., 2002). la fascia pedemontana presenta un rilievo collinare che degrada dalla catena all’area costiera con cianoficee xantoficee zigoficee briofite gloeocapsa sanguinea* vaucheria* oocardium stratum bryum pallens*, pseudotriquetrum homoeothrix janthina*, crustacea spirogyra cratoneuron commutatum* lyngbya martensiana calcarea* zygnema didymodon tophaceus* phormidium incrustatum* diatomee* eucladium verticillatum* pleurocapsa cloroficee hymenostylium curvirostre* rivularia haematites* gongrosira incrustans* horthothecium rufescens* schizothrix lacustris, lateritia, pulvinata, fasciculata gymnostomum calcareum* scytonema myochrous*, julianum brachytecium rivulare* tabella 1 tabella riassuntiva degli organismi che esercitano un controllo primario sulla deposizione dei travertini: le specie sottolineate rivestono effettivamente un ruolo attivo nei processi di precipitazione, mentre le altre fungono solamente da “impalcature”; gli asterischi invece indicano le specie individuate nelle aree di studio (su sfondo grigio quelle più frequenti). table of organisms exercising primary control on travertine deposition: undersigned species have a real active role on precipitation processes while the others have only the function of “scaffolding”; the stars indicate species recognized in the study area (the most frequent species inside grey boxes). quote che vanno da oltre 1000 m a poche centinaia verso la costa. i rilievi sono costituiti da dorsali isolate, legate alla culminazione di terreni calcarei meso-cenozoici, e da rilievi tipo mesa, cuesta e plateaux, impostati su litotipi terrigeni essenzialmente arenaceo-pelitici e pelitico arenacei, con intercalazioni di orizzonti conglomeratici (s e r v i z i o g e o l o g i c o d ’i t a l i a , 1969; cantalamessa et al., 1986; centamore et al., 1991; farabollini, 1995; d’alessandro et al., 2002). questi hanno età riferibile all’intervallo che va dal miocene superiore al pleistocene inferiore e rappresentano il riempimento di bacini di avanfossa e di piggy-back, via via più recenti spostandosi da ovest verso est, e depositi di chiusura (ori et al., 1991; bigi et al., 1995). la strutturazione dell’area è avvenuta tra il pliocene e il pleistocene (calamita et al., 1991 e relativa bibliografia; bigi et al., 1995). dapprima una fase compressiva ha portato alla messa in posto dei principali sistemi di sovrascorrimenti nell’area di catena coinvolgendo progressivamente nell’accavallamento anche i termini di avanfossa via via più orientali. successivamente, alla fase compressiva, ha fatto seguito una attività tettonica distensiva quaternaria, accompagnata da un sollevamento generalizzato (dramis, 1992). nel settore di catena si sono sviluppati importanti sistemi di faglie a direzione nwse e ns con rigetti molto elevati che bordano le principali dorsali e hanno portato alla formazione di ampie conche intermontane. nell’area pedemontana si sono create faglie dirette, anch’esse a direzione da appenninica a ns, ma in genere con rigetti modesti. questi fenomeni determinano un importante condizionamento nella morfogenesi dell’area marchigianoabruzzese e in particolare nell’impostazione e nell’evo261i travertini dell’italia centrale ... luzione del reticolo idrografico e nella distribuzione e tipologia dei processi gravitativi (d r a m i s , 1992; farabollini, 1995). in particolare il settore di catena presenta una morfologia piuttosto aspra sulla quale le sequenze climatiche quaternarie hanno esercitato una influenza notevole, lasciando tracce molto evidenti, date da versanti regolarizzati e detriti stratificati di versante, quest’ultimi prodotti da gelifrazione su versanti denudati dalla copertura vegetale e messi in posto da ruscellamento e movimenti di massa superficiali. la gravità ha infatti svolto e svolge un ruolo molto importante: le evidenze più spettacolari si osservano sui versanti orientali dell’area di catena, dove è possibile riconoscere corone di frana, soprattutto di crollo, a monte delle quali si sono prodotte fessure, gradini, trincee, ondulazioni ed una intensa fratturazione degli strati (dramis et al., 1982; farabollini, 1995). alla sommità dei rilievi sono stati riconosciuti, in limitati lembi di piccola estensione, i resti della paleosuperficie sommitale, la cui frammentazione e dislocazione a quote diverse è da attribuire alla successiva tettonica distensiva ed al sollevamento dell’area, particolarmente intenso e generalizzato a partire dalla fine del pleistocene inferiore (dramis et al., 1982; centamore et al., 1983; dramis, 1992; coltorti & pieruccini, 2000 e relativa bibliografia). alla base del rilievo calcareo, incassata nella superficie precedentemente descritta, è riconoscibile una seconda superficie di spianamento, attribuita dal demangeot (1965) al villafranchiano. essa è stata riconosciuta in tutta l’area esaminata, in corrispondenza dei depositi mio-plio-pleistocenici, dove è ben conservata in estesi lembi presenti sugli spartiacque dei principali fiumi, presentando ondulazioni di quota, comparabili con la superficie sommitale e con i depositi siciliano-crotoniani di chiusura (dramis, 1992; farabollini, 1995). nell’ampia area pedemontana i processi morfogenetici legati alla gravità sono responsabili di una franosità, molto diffusa ed intensa; i processi legati alle acque correnti superficiali hanno modellato un reticolo idrografico molto sviluppato e ampie valli fluviali a decorso prevalentemente ne-sw con gradienti modesti; queste sono solcate dai corsi d’acqua principali che danno origine ad ampie piane alluvionali, con piccole cimose costiere in corrispondenza della foce (coltorti, 1981; d r a m i s et al., 1982; c o l t o r t i et al., 1991; farabollini, 1995). l’evoluzione geomorfologica ha determinato la formazione di più o meno estese coltri di depositi continentali quaternari, costituiti da depositi di versante, alluvionali e lacustri nell’area di catena e nelle principali conche intermontane. al di fuori delle dorsali, nell’area pedemontana, lungo le valli dei fiumi principali, sono presenti depositi alluvionali, disposti in quattro ordini di terrazzi ad altezze decrescenti sul fondovalle, connessi alle fasi fredde pleistoceniche e, nelle epoche più recenti, condizionati dall’attività antropica (coltorti, 1981; coltorti et al., 1991; farabollini, 1995). 3. genesi e meccanismi deposizionali il travertino rappresenta uno fra i depositi continentali più diffusi nell’area di studio e la sua età, molto fig. 1 ubicazione dei principali depositi travertinosi (in grigio) dell’italia centrale adriatica. in nero sono riportati i depositi travertinosi descritti nel presente lavoro. location of main travertine deposits (grey points) of the adriatic central italy. black points indicate travertine deposits described in the present work. 262 spesso di non facile collocazione vista la carenza di elementi di datazione, varia generalmente tra il pleistocene medio e l'attuale. generalmente l’origine dei travertini viene in letteratura attribuita ad acque sorgive sovrassature in anidride carbonica. l’analisi di facies (d’argenio & ferreri, 1992; golubic et al., 1993; cilla et al., 1994; farabollini, 1995; materazzi, 1996) evidenzia un meccanismo deposizionale caratterizzato da flussi laminari e turbolenti. i primi depositano croste stromatolitiche ad andamento suborizzontale, cui si associano piccoli canali (in cui avviene la deposizione di sabbie grossolane e ghiaie fitoclastiche a stratificazione incrociata) e talvolta piccoli bacini lacustri, mentre i secondi si realizzano in corrispondenza di cascate e rapide nelle quali si ha la formazione di travertino fitoermale. numerose sono le classificazioni delle morfologie associate alla deposizione di travertino. già nel 1978, buccino et al. (1978), avevano messo in evidenza, nei depositi travertinosi della bassa valle del tanagro (campania), l'esistenza di facies fitoclastiche e fitoermali ipotizzando anche un modello di dinamica fluviale per spiegarne la genesi. successivamente chafets & folk (1984), prendendo anche in considerazione il ruolo rivestito dalle diverse specie vegetali nei processi di incrostazione, dall'esame di alcune località dell'italia centrale e degli stati uniti centro-occidentali, hanno identificato cinque categorie distinte in: waterfall or cascade deposits; shallow lake-fill deposits; sloping mounds, fans and cones; terraces mounds; fissure ridges. nel 1990 pedley, distinse i depositi sulla base del loro angolo di deposizione, della tipologia del flusso d'acqua, delle colonizzazioni microbiologiche e della temperatura ambiente. su tali basi, l'autore riconosce cinque differenti tipi di morfologie: travertini di sorgente, di cascata, fluviali, palustri e lacustri, ognuno composto da una particolare associazione di facies deposizionali detritiche o biocostruite. requisito fondamentale è la quasi totale prevalenza in queste facies della precipitazione legata agli organismi vegetali e/o batterici, anche se viene comunque rilevato un piccolo contributo da parte di processi "inorganici". riprendendo lavori effettuati precedentemente, golubic et al. (1993) riconoscono, per i travertini pleistocenici di rocchetta a volturno, nell'appennino centro-meridionale, sei associazioni di litofacies sulla base delle loro caratteristiche stratigrafico-sedimentarie e sul loro contenuto fossilifero (inclusi anche i supporti vegetali): 1) calcareous sand with travertine intercalations: shallow lacustrine facies; 2) phytoclastic calcarenite and phytohermal travertine: swamp, or shallow sublittoral facies; 3) phytoclastic packstone-grainstone and stromatolitic travertine: gentle slope facies; 4) phytoclastic rudstone, microhermal and stromatolitic travertine: steep slope facies; 5) micro-, and phytohermal travertine and stromatolitic travertine: pool terrace facies; 6) phytohermal travertine: rapids and waterfalls facies. la ricerca si completa anche di uno studio dettagliato sull'ecologia dell'alga desmidiacea oocardium stratum e delle sue caratteristiche sedimentologiche quando viene rinvenuta nei travertini "fossili". i criteri di classificazione sopra citati forniscono un quadro abbastanza chiaro delle litofacies presenti e degli ambienti caratteristici della maggior parte dei travertini conosciuti, non associabili a fenomeni di termalismo. sulla base di questi lavori sono stati condotti rilevamenti geomorfologici e analisi di dettaglio dei principali affioramenti di travertino presenti nell’area marchigiano-abruzzese (fig. 1). le indagini condotte hanno permesso di proporre un modello deposizionale (fig. 2) per i travertini dell'area adriatica marchigiano-abruzzese, che a differenza degli autori sopracitati, tiene conto di ambienti deposizionali a più ampia scala che in molti casi comprendono, contemporaneamente, diverse condizioni morfologiche particolari e più o meno localizzate. per ciascun ambiente sono indicate le caratteristiche essenziali e sono descritti gli affioramenti delle località ritenute più significative. ambiente 1: "aree di sorgente o di versante" questa situazione si riferisce ai travertini che si sviluppano o sugli orifizi delle sorgenti o in aree molto prossime a queste; in tali condizioni le acque sorgive o che comunque hanno percorso tratti molto brevi, liberano la maggior parte della co2 che contengono, favorendo la deposizione del carbonato di calcio che va così ad incrostare spontaneamente sia il substrato che le specie vegetali presenti. in questo caso, la presenza di muschi ed alghe "calcaricole" come le briofite, le cianoficee e le diatomee, peraltro molto numerose in queste zone, sembra non abbia un ruolo così determinante come testimoniato dalla presenza anche di foglie, frustoli o ciottoli ricoperti di caco3. nelle sorgenti vere e proprie, il travertino si deposita a formare piccole collinette intorno all'orifizio ma in qualche caso, ove sono presenti pareti rocciose o massi, può formare anche delle strutture tipo cuscinetto, simili ai "cushions" ed ai "curtains" del modello di cascata di pedley (1990). questi depositi nell'area non hanno di solito dimensioni notevoli ma sono abbastanza frequenti e si localizzano in molte delle sorgenti provenienti dagli acquiferi carbonatici della dorsale umbro-marchigiano-abruzzese. lo schema di figura 2 mostra una situazione abbastanza comune per le aree prossime alla sorgente; queste zone, sono caratterizzate da piccoli rivoli d'acqua che variano continuamente il loro percorso e la loro portata generando una struttura "a gradoni", con piccole pozze dove l'acqua ristagna temporaneamente, ed altre parti dove invece ha uno scorrimento stilicidiale o leggermente canalizzato. quest'ultimo è l'ambiente ideale per lo sviluppo delle specie vegetali come le briofite ed in generale di gran parte delle comunità algali che vivono parzialmente o temporaneamente sommerse dall'acqua; esse incrostandosi formano dei piccoli terrazzetti che tendono a progradare verso l'avanti-basso. nelle pozze invece, si ha una deposizione di tipo detritico: sabbie fitoclastiche si alternano a piccole lenti o straterelli di ghiaie travertinose o a frammenti di fitoerme che sono il prodotto del disfacimento delle facies concrezionate limitrofe. una situazione simile è stata osservata anche all'interno di piccoli canali presenti sui versanti: in questo caso la deposizione è legata all'attività, molte volte temporanea o stagionale, di piccoli fossi tributari del corso principale (es. fiastra e castelli; fig. 1) p. farabollini et al. 263 l’esempio di sant’angelo alla testata della valle del fosso sant’angelo, affluente di sinistra del fiume esino a ridosso della dorsale umbro-marchigiana è possibile osservare un affioramento di travertino tuttora in formazione (fig. 3). il deposito, che mostra un fronte alto più o meno una decina di metri ed è seguibile lateralmente per circa 20÷25 metri, è caratterizzato dalla presenza di briofite come il cratoneuron commutatum, l'eucladium verticillatum e la specie brachytecium rivulare (materazzi, 1996) e mostra una caratteristica morfologia "a gradoni" con presenza di piccoli corsi d'acqua che scendono variando continuamente il loro percorso. la formazione di questo deposito, che mostra una progressiva migrazione verso la destra idrografica, sembra essere iniziata nell'olocene, probabilmente con un'intensità maggiore, ed è continuata fino al giorno d'oggi; la presenza di travertino nell'area in tempi passati è comunque testimoniata da altri due piccoli depositi situati più a valle, ora inattivi, attribuiti all'olocene per la loro posizione rispetto ai depositi alluvionali di fondovalle (materazzi, 1996). ambiente 2: "cascata" in questo secondo caso (fig. 2), rientrano tutti quei depositi che si sviluppano sui fondovalle, dove fig. 3 travertino in formazione nella valle sant’angelo; aeucladium verticillatum; bbachytecium rivulare; ccratoneuron commutatum. travertine deposition in the s. angelo valley; aeucladium verticillatum; bbachytecium rivulare; ccratoneuron commutatum. fig. 2 classificazione degli ambienti deposizionali di travertino per l’area marchigiano-abruzzese. per la descrizione si veda il testo. classification of travertine d e p o s i t i o n a l environments in the abruzzimarchean region. for e x p l a n a t i o n see the text. i travertini dell’italia centrale ... 264 sono presenti nette rotture di pendio o anche dove il gradiente generalmente supera, anche per brevi tratti, una pendenza di 3°÷5°. le situazioni più frequenti sono quelle che ricorrono o al contatto di litologie con forte contrasto di competenza o in prossimità di discontinuità tettoniche (faglie) o in condizioni morfologiche particolari che determinano un disequilibrio nel profilo longitudinale di un corso d'acqua. nel primo caso, tipico dell'area umbro-marchigiana, si può avere la formazione di soglie al contatto tra i termini calcarei e selciferi e quelli più marnosi della successione umbro-marchigiana; soglie morfologicamente simili si possono formare anche per l'azione di faglie normali o trascorrenti con componente diretta. il terzo caso può verificarsi ad esempio alla confluenza di valli con differente grado di approfondimento, dovuto o alla diversità dei terreni attraversati, o alla presenza di condizioni strutturali favorevoli (valli impostate lungo linee tettoniche). l'ambiente in questione, corrispondente in parte al "cascade model" di pedley (1990) o alle litofacies 4, 5 e 6 di golubic et al. (1993), presenta facies deposizionali per certi versi molto simili a quelle osservate nelle aree di sorgente ma se ne differenzia sostanzialmente per due aspetti fondamentali: il primo è che ormai ci troviamo relativamente "lontani" dalla zona di sorgente (di solito qualche chilometro più a valle) e la deposizione avviene sul fondovalle, all'interno dell'alveo e non sui versanti; il secondo è che il fiume, a differenza dell'ambiente precedente, oramai ha un suo corso ben definito, così come l'apporto d'acqua che appare più cospicuo, costante e ben canalizzato. le barriere di travertino che si vengono così a formare, sono costituite quasi totalmente da facies fitoermali mentre quelle fitoclastiche sono presenti in piccoli lenti o livelli; il rapporto tra queste due, in un'ipotetica sezione verticale, è maggiore di 10:1. per quanto riguarda gli elementi costituenti il deposito si può affermare che in questo caso, trovandoci ad una certa distanza dalla sorgente, il contributo delle specie vegetali nella costruzione dell'edificio travertinoso diventa molto consistente: tuttavia permane una discreta componente "inorganica" testimoniata dalla presenza di frustoli, ramoscelli e foglie insieme alle specie propriamente incrostanti. queste ultime sono rappresentate soprattutto da briofite come il cratoneuron commutatum, l'eucladium verticillatum e il didymodon tophaceus, da stromatoliti associate alle diatomee, e in parte anche da cianoficee, come il phormidium incrustatum, che come sappiamo crescono spesso come epitesi sui muschi. questi organismi, sebbene osservati comunemente all'interno di molti dei depositi conosciuti (kempe & emeis,1985; pedley, 1990; golubic et al., 1993) e segnalati lungo i corsi d'acqua in esame, non sono però stati riconosciuti direttamente in tutti i depositi dell'area umbro-marchigiana; nella maggioranza dei casi infatti i depositi sono oramai inattivi, le specie vegetali sono pressoché scomparse dalla loro superficie e le stesse strutture originarie sono state alterate dalla circolazione secondaria delle acque. il loro riconoscimento, ove possibile, è stato ottenuto sulla base di confronti fra le strutture relitte e quelle viventi (materazzi, 1996). il blocco diagramma di figura 2 mostra una delle possibili condizioni morfologiche che possono portare alla formazione di un ambiente di "cascata". il travertino che si viene così a costituire forma una vera e propria barriera che al momento della deposizione tende a progradare verso l'avanti-alto. la notevole porosità associata a questi edifici (e di solito inversamente proporzionale all’età dei depositi), fa si che lo sviluppo sia molto consistente e anche molto rapido: un evidente esempio è quello della penisola balcanica dove in circa 12000 anni dalla fine dell'ultima glaciazione, si sono edificate barriere di travertino alte fino a 50 m (golubic et al., 1993). tale condizione trova anche giustificazione dal fatto che tale processo, una volta iniziato, tende ad autoamplificarsi: infatti si assiste ad un aumento del tempo di permanenza dell'acqua all'interno della struttura con conseguente aumento dei processi microbiologici; questi a loro volta, creano una nuova catena biologica favorita anche dalla presenza di rapide e cascate che determinano zone fortemente areate, ideali per lo sviluppo di nuove specie. l’esempio di roccamontepiano la placca di travertino, che sorge alle spalle dell’abitato di roccamontepiano (nell’abruzzo teramano) e che costituisce un altipiano situato a circa 650 m s.l.m., è dato da un affioramento tabulare di travertini, di forma sub-rettangolare, allungato in direzione grossomodo appenninica. tale placca poggia, nella sua parte meridionale, mediante contatto erosivo, su sedimenti sabbioso-conglomeratici, spessi 5÷6 m, che a loro volta poggiano sui litotipi argillosi marini (fig. 4); queste litologie sono probabilmente attribuibili alla formazione di mutignano (d’alessandro et al., 2002). l’estesa copertura detritica, presente ai piedi di tale placca, non permette di osservare altrove tale contatto; sembra comunque che, per la maggior parte della sua estensione, essa poggi sulla formazione argillosa marina. l’estesa placca travertinosa è costituita da diverse litofacies sviluppate sia in senso orizzontale che verticale, riconoscibili anche alla scala decimetrica (fig. 4). in particolare la parte inferiore dell’affioramento è caratterizzata in prevalenza da sabbie e limi calcarei, stratificati, e da lenti di travertini stromatolitici e oncoliti; verso l’alto passano a calcareniti e calciruditi fitoclastiche, organizzate in strati spessi e irregolari, frequentemente anastomizzati, con lenti di travertini fitoermali. il settore settentrionale e quello nord-orientale sono caratterizzati da travertini microermali di incrostazione su muschi, e stromatolitici, con stratificazioni ondulate disposte a formare delle vasche, riempite da calcareniti fitoclastiche a stratificazione piano-parallela e sub-orizzontale. lo spessore dei travertini è variabile da 15 a 40 m, con valori massimi sul bordo orientale del pianoro (d’alessandro et al., 2002). al di sopra del deposito travertinoso è presente un paleosuolo di tipo fersiallitico, molto evoluto e ricco in frammenti di selce e concrezioni ferro-manganesifere, con spessore anche fino ad un metro. la posizione morfo-stratigrafica di questi sedimenti, in relazione ai depositi alluvionali terrazzati affioranti lungo le valli del f. alento e del f. foro, insieme alla presenza del paleosuolo al tetto dei travertini, permettono di riferirne l’età al pleistocene medio e più precisamente, in analogia con quelli di civitella del tronto, alla penultima fase interglaciale. p. farabollini et al. l’esempio di civitella del tronto i travertini di civitella del tronto, sono distribuiti in tre affioramenti che da nord verso sud sono: monte santo (544 m), civitella del tronto (645 m) e colle san nicola (671 m). tali depositi, il cui spessore varia in modo molto brusco tra 50 e 5 metri, si presentano in forma di placche, con pareti a picco e con geometria vagamente cuneiforme in direzione all’incirca ns. nel complesso le tre placche sembrano avere una forma lenticolare, in cui il maggior spessore della parte centrale, disposta secondo la direzione del corso fluviale del salinello, si trova in corrispondenza dell’abitato di civitella del tronto. la placca travertinosa poggia su una superficie di erosione che taglia il substrato arenaceo-pelitico della laga, come nel caso di civitella del tronto, o su ciottoli grossolani arrotondati e subarrotondati di origine fluviale, con una parvenza di embriaciatura che sembra indicare una corrente con direzione circa ns, come nel caso di montesanto o di colle san nicola (farabollini, 1999). superiormente si rinvengono sabbie e ghiaie travertinose (sh e gp di miall, 1978) a cui sono associate facies tipicamente fluviali caratterizzate da stratificazioni, gradazioni, ecc., per uno spessore variabile tra i 20÷30cm, che passano gradualmente ad una associazione data da alternanze di sabbie travertinose e travertini fitoermali ad indicare ambienti di polle con frequenti incursioni di acque calcarifere. lateralmente ed anche al di sopra di questa associazione, ne è riconoscibile una seconda formata da travertino microermale, travertino stromatolitico e fitoermale. al loro interno è possibile osservare piccoli canali riempiti da ciottoli travertinosi arrotondati e/o da pisoliti con diametro a volte superiore ai 2÷3cm. tale associazione permette di ipotizzare la presenza di un pendio più o meno acclive dove la deposizione travertinosa contribuiva ad accrescerne l’acclività. alla sommità è presente un livello di spessore notevole (circa 20 metri a civitella del tronto) caratterizzato da travertino fitoermale che indica rotture di pendio importanti e la progradazione verso valle delle facies di cascata (farabollini, 1999). nella placca di colle san nicola inoltre è stato differenziato un livello sommitale più poroso, assente negli altri due depositi, che presenta il rapporto tra gli isotopi del carbonio nettamente differente, anche se le altre caratteristiche si mantengono all’incirca simili (preite martinez et al., 1990). lo studio, a carattere palinologico (de sanctis & fregonese, 1981), ha messo in evidenza che la deposizione dei travertini dell’area di civitella del tronto, nel complesso sembra essere avvenuta in un contesto climatico tipicamente interglaciale, in cui i materiali più porosi (come il livello presente alla sommità della placca travertinosa di colle san nicola e che gli autori sopra citati indicano come più recenti) sarebbero riferibili ad un ambiente di clima temperato caldo, mentre quelli più massivi, si sarebbero depositati in condizioni climatiche più fredde. le evidenze geomorfologiche, come la presenza di un lembo di terrazzo alluvionale del ii ordine, posto a circa 50 metri più a valle, attribuito alla fase finale del pleistocene medio, la posizione topografica delle placche rispetto a questo deposito, la presenza alla base delle placche di travertino di clasti calcarei arrotondati di chiara origine fluviale che marcano un antico fondovalle pre-ii ordine (farabollini, 1999), testimoniano che la deposizione dei travertini è più antica della fase alluvionale del pleistocene medio finale e può essere indicativamente riferita al penultimo interglaciale. ambiente 3: "cascate e vasche" e' sicuramente una delle situazioni più frequenti tra quelle osservate nel presente studio e tra quelle segnalate in letteratura (cilla et al., 1994; calderoni et al., 1996a e b; dramis et al., 1999; farabollini et al., 2003). l'ambiente in questione è per certi versi molto simile a quello di "cascata". anche in questo caso infatti ci troviamo in una porzione del corso d'acqua caratterizzata da un gradiente mediamente alto e da rotture del profilo longitudinale più o meno sviluppate e pure le 265 fig. 4 sezione schematica della placca travertinosa di montepiano. tftravertino fitoermale; lsmlenti stromatolitiche e microermali; tfctravertino fitoclastico; lfelenti fitoermali; ononcoliti; sltsabbie e limi travertinosi; cmconglomerati marino (formazione di mutignano); lamlimi ed argille marine (formazione di mutignano). schematic profile of the montepiano travertine plate. tf – phytohermal travertine; lsm – stromatolitic and microhermal lens; tfc – phytoclastic travertine; lfe – phytohermal lens; on – oncolites; slt – travertine sands and silts; cmmarine conglomerates (formazione di mutignano); lammarine silts and clays (formazione di mutignano). i travertini dell’italia centrale ... condizioni morfologiche sono pressoché identiche: tettonica e assetto strutturale delle varie litologie presenti, restano infatti i fattori condizionanti la formazione di questi depositi mentre la differenza è legata unicamente all'entità dei dislivelli e alla gradualità della pendenza del profilo longitudinale del corso d'acqua. il modello proposto, rappresentato schematicamente in figura 2, si differenzia dal "phytoherm framestone barrage" di pedley (1990) per la forma finale dell'edificio. tale modello inoltre raggruppa le associazioni di litofacies 1 e 3 di golubic et al. (1993) e variamente anche le litofacies 4, 5 e 6, riconosciute peraltro anche nell'ambiente di "cascata". il deposito che si forma in questo contesto è costituito da un'alternanza di facies fitoermali (uguali a quelle dell'ambiente di "cascata", ma con maggiore presenza di travertino stromatolitico) e facies fitoclastiche di vario spessore, costituite da corpi e livelli limosi, sabbiosi e ghiaiosi, massivi o stratificati. facendo riferimento all'ambiente 2, queste sono presenti in un rapporto minore di 10:1 anche se, nella maggioranza dei casi, questo rapporto può scendere fino a 1:1 o addirittura mostrare una prevalenza delle facies fitoclastiche su quelle fitoermali. per quanto riguarda la dinamica di formazione, come abbiamo detto, la situazione è molto simile a quella descritta nell'ambiente di "cascata". lungo il corso d'acqua infatti, in prossimità di queste piccole rotture di pendio, si formavano dei banconi di travertino fitoermale in facies di cascata che tendevano a progradare verso l'avanti-alto; nelle zone di raccordo tra i banconi invece, dove il gradiente era pressoché nullo si depositavano delle facies detritiche prevalentemente sabbiose (fitoclastiche), provenienti dall'erosione dei corpi fitoermali più a monte. con il procedere della deposizione, l'edificio si accresceva realizzando una sovrapposizione dei termini fitoermali su quelli fitoclastici. in questa tipologia di ambiente ricadono, come già specificato, la maggior parte dei depositi travertinosi riconosciuti nell’area di studio (sefro, pievetorina, roccafluvione, ecc.) l’esempio di sefro in questa località, il deposito travertinoso, che forma un bancone di spessore modesto (3÷5 m), presenta la morfologia tipica di un sistema di "cascate e vasche", sebbene le facies fitoermali di cascata siano maggiormente sviluppate. la presenza di tale bancone a livello dell'alveo attuale del torrente scarzito ed i suoi rapporti con i depositi fluviali e lacustri, permettono di ipotizzare una deposizione alquanto recente, cioè durante l'optimum climatico dell'olocene (materazzi, 1996). poco più a valle del deposito descritto, in sinistra idrografica, è presente un piccolo lembo di travertino depositatosi al di sopra di uno deposito ghiaioso, di origine fluviale, discretamente cementato, del pleistocene medio-finale (materazzi, 1996). al tetto della sequenza, depositi detriti stratificati di versante del pleistocene superiore sigillano il deposito stesso, collocando così questa fase deposizionale durante l'ultimo interglaciale (fig. 5). al contatto tra le ghiaie fluviali ed il travertino è stato rinvenuto un paleosuolo fersiallitico parzialmente colluviato, solitamente presente al tetto dei depositi alluvionali del i e del ii ordine (coltorti, 1981; coltorti et al., 1991) a conferma dell’antichità di tale deposito rispetto a quello presente lungo l’alveo fluviale. il meccanismo deposizionale e le varie facies sono praticamente le stesse che caratterizzano il deposito riconosciuto a serravalle di chienti lungo l’alveo del fiume chienti, dove presenta uno spessore di pochi metri. fig. 5 sezione schematica del deposito di travertino di sefro (tftravertino fitoermale). schematic profile of the travertine deposit at sefro (tf – phytohermal travertine). l’esempio di pievetorina nei pressi dell’abitato di pievetorina, lungo una valle trasversale al fiume chienti (fig. 1) sono presenti due diverse generazioni di depositi travertinosi, di cui la più antica, è posta a diverse decine di metri sul talweg mentre l’altra, più recente, si sviluppa in destra idrografica del fosso di pievetorina a quote di pochi metri dall’alveo attuale. in particolare i depositi più significativi sono rappresentati proprio da questi ultimi, in quanto si sviluppano per qualche centinaia di metri lungo l’asse fluviale anche se sono generalmente affioranti solo in destra idrografica. i depositi più antichi, poco estesi e generalmente obliterati da una estesa copertura detritica e colluviale, costituiscono un piccolo terrazzo di travertino alto pochi metri e seguibile, anche se in maniera discontinua per la fitta vegetazione, per circa 20÷30 metri. i depositi più bassi invece sono dati da una sequenza travertinosa di notevole spessore, fino a 10 266 p. farabollini et al. metri, e seppur mascherati in superficie da coltri colluviali spesse anche fino a un metro, sono ben visibili per effetto dell'incisione fluviale (fig. 6). essi sono formati dall'alternanza di facies fitoclastiche (tfc: ghiaie, sabbie e limi travertinosi) e facies fitoermali (tf: travertino concrezionato in posto). fig. 6 foto dell’affioramento del travertino di pievetorina (tftravertino fitoermale; tfctravertino fitoclastico). travertine deposit at pievetorina (tf phytohermal travertine; tfc phytoclastic travertine) dal basso verso l'alto, sono stati osservati 60 cm di sabbie molto fini e limi travertinosi con piccole lenti di ghiaie travertinose fini a stratificazione planare (gp di miall, 1978), osservabile in corrispondenza del letto fluviale; verso monte e superiormente, per circa 4÷5 metri, queste facies passano a banconi di travertino fitoermale compatto, inclinato di circa 20°÷25° contromonte. al di sopra, per circa un metro e mezzo, sono visibili alternanze di sabbie fini e limi travertinosi dello spessore di 20÷40 cm e di limi argillosi scuri, spessi da 1 a 4÷5 cm. in alcuni casi si riconoscono sottili livelli argillosi dello spessore di circa 10 cm. inoltre si riconoscono livelli di ghiaie travertinose molto grossolane che arrivano fino alle dimensioni di vari centimetri di diametro: si tratta generalmente di frammenti di travertino fitoermale e di travertino stromatolitico prodotto dal disfacimento di banconi di travertino fitoermale situati più a monte. procedendo verso l'alto la sequenza evidenzia la presenza di banconi di travertino fitoermale con inclinazione di circa 20° contromonte. al tetto della sequenza è stato infine riconosciuto un suolo bruno alluvionale contenente ciottoli di travertino fitoermale detritico spessi fino a 10 cm. l’esempio di roccafluvione il deposito in questione è posto lungo la valle del torrente fluvione, in corrispondenza dell’abitato di roccafluvione, ad una quota di circa 275m s.l.m., e si estende verso valle per una lunghezza di circa 800 m, con uno spessore massimo di circa 10 metri. in particolare il deposito studiato è ubicato al di sopra della piana alluvionale di iii ordine su cui sorge l’abitato di roccafluvione, e risulta inciso dal corso d’acqua attuale, posto circa 20 metri più in basso. le scarpate fluviali, generalmente scolpite nei litotipi della formazione della laga, permettono di verificare come, sia in destra che in sinistra idrografica, al di sopra del substrato arenaceo, siano presenti depositi travertinosi fitoermali, di spessore di circa 6 metri, clinostratificati verso monte di qualche grado, e che si estendono anche diverse decine di metri. verso l’alto essi passano a facies tipicamente fitoclastiche, costituite da sabbie e limi travertinosi e subordinatamente ghiaie travertinose. lungo la piana alluvionale che costituisce il terrazzo di iii ordine, lavori di sbancamento per la realizzazione di opere infrastrutturali, hanno permesso di verificare come il deposito travertinoso poggi, a luoghi, sui depositi alluvionali terrazzati dati da ghiaie grossolane eterometriche e poligeniche, immerse in abbondante matrice sabbioso-argillosa, per uno spessore di circa 1 metro, che riempiono canali scavati nel substrato (facies gm e gt di miall, 1978). anche se la sezione presenta una altezza di circa 2 metri ed una estensione laterale di qualche decina di metri, è comunque possibile valutare i rapporti reciproci tra i vari deposti presenti. in particolare i depositi travertinosi sono rappresentati da facies fitoermali, generalmente accresciuti su supporti vegetali dati principalmente da muschi, rami e foglie, che passano lateralmente a travertino fitoclastico e croste stromatolitiche, che formano corpi che presentano estensione laterale anche dell’ordine di diversi metri. alla sommità, al di sopra di materiali colluviali, è presente un suolo brunastro riconoscibile per tutta l’estensione della piana alluvionale del iii ordine. ambiente 4: "canali travertinosi delle piane alluvionali" questa situazione, abbastanza ricorrente, è caratteristica delle aree esterne alla dorsale carbonatica marchigiano-abruzzese dove il gradiente diminuisce fortemente e dove le valli si allargano, ormai modellate nei terreni recenti più erodibili (marnosi, arenacei ed argillosi). in queste zone, alla fine del pleistocene superiore, avveniva la deposizione delle alluvioni terrazzate del iii ordine che formavano ampie pianure in regime braided. con l'inizio dell'olocene però il regime cambiava; il generale miglioramento climatico favoriva infatti lo sviluppo della vegetazione sui versanti e la conseguente diminuzione del carico solido negli alvei innescava processi di incisione e portava alla formazione di canali che incidevano debolmente la sommità del terrazzo pleistocenico. proprio all'interno di questi canali avveniva, durante i periodi più caldi dell'olocene, la deposizione di piccoli spessori di facies fitoclastiche e fitoermali di travertino. sempre facendo riferimento ai criteri di classificazione di pedley (1990) e di golubic et al. (1993), queste facies possono essere paragonate al "braided fluviatile model" del primo o alle litofacies 1 e 3 dell'autore slavo e sono costituite principalmente da 267i travertini dell’italia centrale ... livelli ghiaiosi e sabbiosi fitoclastici, spesso a stratificazione incrociata (tipici di canali a sinuosità mediobassa) e da piccole fitoerme dove frequente è la presenza di travertino stromatolitico (fig. 2). l’esempio di pioraco in questa zona, circa un paio di chilometri a monte dell'abitato di castelraimondo, la piana alluvionale del pleistocene superiore del fiume potenza ha un'estensione laterale di circa 500m mentre lo spessore del deposito si aggira sui 10÷15 m. al tetto di questo deposito sono riconoscibili alcuni piccoli canali, incisi per circa 1÷1,50 m riempiti a tratti da facies fitoclastiche e fitoermali di travertino e da travertino stromatolitico che marcavano le fasi di magra dell'attività del canale. l’esempio di serrapetrona lungo l’alta valle di un affluente di sinistra del fiume chienti, nei pressi di serrapetrona, nel versante orientale della dorsale marchigiana, è stata osservata una potente sequenza detritica ed alluvionale (fig. 7), di circa 40 metri, posta ad alcune decine di metri sul corso attuale. in particolare dal basso verso l’alto la sequenza risulta costituita, per circa 35 m di spessore, da livelli detritici (dv) grossolani e subangolosi ai quali si intercalano ed alternano, a varie altezze, livelli tipicamente fluviali (facies gt di miall, 1978), dati da clasti subarrotondati appiattiti e ben addensati, che mostrano una debole stratificazione incrociata a basso angolo. superiormente la sequenza è caratterizzata dalla presenza di sedimenti clastici subangolari per uno spessore complessivo di 4 metri, che seppelliscono un paleosuolo bruno calcico (pb) di circa 10 cm, e ricoprono in parte un paleocanale ghiaioso, profondo circa 3 metri e con spessore di circa 1,5 metri. all’interno del deposito il ritrovamento di materiali ceramici fluitati di epoca storica è stato collegato con il denudamento dei versanti operato dall’uomo in epoca storica che avrebbero innescato intensi fenomeni di erosione con formazione di spessi corpi colluviali ai piedi del versante (farabollini, 1995; calderoni et al., 1996b). alla base del canale si osservano lenti ghiaiose grossolane (facies gm di miall, 1978), alle quali si alternano livelli centimetrici di travertino fitoermale e croste stromatolitiche (tf), a testimonianza di condizioni climatiche di tipo temperato umido caratterizzato dalla presenza di una estesa copertura vegetale. all’interno di un livello argilloso nerastro (la), di 30÷40cm, con scheletro costituito da clasti subangolari di 2÷10 cm, sono stati trovati numerosi frammenti ceramici non fluitati, quest’ultimi attribuiti all’eneolitico (farabollini, 1995; calderoni et al., 1996b). la datazione radiometrica effettuata su carboni presenti in tale livello, che ha fornito una età di 4750±65 (calderoni et al., 1996b), permette di riferire la sequenza all’olocene antico. il canale è colmato da un metro di sabbie fitoclastiche a stratificazione piano-parallela (sfc) che passano lateralmente a travertino fitoermale. 4. cronologia e significato paleoambientale la deposizione del travertino nell’area adriatica marchigiano-abruzzese è sicuramente un fenomeno molto importante ai fini della ricostruzione del contesto paleoambientale del quaternario. le differenti fasi deposizionali osservate, infatti, possono essere inquadrate in periodi climatici e/o storici ben precisi. in primo luogo appare evidente come, in assenza di fenomeni particolari (idrotermalismo o presenza di acque “acide” generalmente sulfuree, di provenienza profonda) il contesto climatico sia senza dubbio fondamentale per spiegare la genesi e lo sviluppo di tali depositi; la presenza di travertino all'interno delle valli fluviali durante il quaternario, è innanzitutto un fenomeno generalizzato e più o meno contemporaneo a livello mondiale nei paesi temperati o attualmente subtropicali (ford & pedley, 1996 e relativa bibliografia; materazzi, 1996 e relativa bibliografia). come evidenziato in particolare da nicod (1986), la grande quantità di carbonato in soluzione, responsabile della formazione del travertino, è legato alla forte presenza di co2 nelle acque percolanti il substrato calcareo; questo gas, di origine biologica, è a sua volta legato allo sviluppo di potenti spessori di suoli formatisi nei periodi interglaciali quando il generale riscaldamento successivo alle fasi fredde glaciali aveva favorito l'incremento della vegetazione sui versanti. una così cospicua copertura vegetale favoriva anche la regolarizzazione del regime idrico: la capacità dei suoli di trattenere le acque, che poi venivano restituite all'alveo in un periodo di tempo più lungo, permetteva un arricchimento maggiore di anidride carbonica e 268 fig. 7 sezione schematica del deposito di travertino di serrapetrona (pb paleosuolo bruno; tf travertino fitoermale; gmghiaie; sfcsabbie fitoclastiche a stratificazione piano-parallela; lalivello antropico; dvdetriti di versante; gtghiaie a stratificazione incrociata a basso angolo). schematic profile of serrapetrona travertine deposit (pbbrown paleosoil; tfphytohermal travertine; gmgravels; sfcplanar cross-bedded phytoclastic sands; laanthropic level; dvslope deposit; gtlow angle through cross-bedded gravels). p. farabollini et al. assicurava inoltre ai corsi d'acqua un costante, anche se non ingente, apporto d'acqua, condizione estremamente vantaggiosa per lo sviluppo delle specie vegetali costituenti il travertino (muschi ed alghe). i dati cronologici raccolti nell’area di studio concordano perfettamente con le premesse suddette; per quanto riguarda i depositi più “antichi”, dei quali non si è potuto effettuare datazioni assolute (civitella del tronto, roccamontepiano, sefro), la loro collocazione stratigrafica rispetto ad altri elementi geomorfologici noti (depositi alluvionali terrazzati, conoidi alluvionali, depositi di versante, paleosuoli ecc.) ha permesso infatti di inquadrare la deposizione in un contesto climatico caldoumido come quello tipico dei periodi interglaciali. i depositi recenti invece (s. angelo, serrapetrona, pievetorina, pioraco; roccafluvione, ecc.), anche sulla base di datazioni radiometriche effettuate essenzialmente su resti vegetali fossili, possono essere collocati in un periodo compreso fra l’olocene antico (preboreale, circa 9000 yr b.p.) e il subatlantico (circa 3000 yr b.p.) fatta esclusione per i depositi ancora in formazione (es. s. angelo, castelli). tale fase si inquadrerebbe perfettamente (almeno nel periodo preboreale-atlantico, fino a circa 5300 yr b.p.) nell’ ”optimum climatico” olocenico, caratterizzato da una generale fase di riscaldamento (2°÷3° in più rispetto al presente nelle medie ed alte latitudini, zubakov & borzenkova, 1990). tali dati sarebbero inoltre in linea con quelli osservati in altre località dell’appennino centrale (calderoni et al., 1996b; cilla et al., 1994; materazzi, 1996). il fattore climatico, in concomitanza con gli eventi tettonici pleistocenici, sembrerebbe poi spiegare anche il differente sviluppo (inteso in senso di estensione areale e di spessore) dei travertini antichi, solitamente maggiore rispetto a quelli olocenici. da una parte infatti, la durata maggiore sia delle fasi fredde, che dei periodi interglaciali del pleistocene inferiore e medio, potrebbe giustificare uno sviluppo maggiore dei travertini proprio per un più lungo perdurare delle condizioni favorevoli alla deposizione. d’altro canto, il forte sollevamento tettonico pleistocenico (dramis, 1992) favoriva anche l’approfondimento, soprattutto nei periodi interglaciali caratterizzati da un incremento dell’erosione lineare, delle valle fluviali con conseguente rapido abbassamento della superficie piezometrica ed aumento del regime idrologico dei corsi d’acqua (farabollini et al., 2003). tale effetto, più intenso inizialmente, veniva progressivamente diminuendo in relazione al riequilibrio con il nuovo livello piezometrico di base (fig. 8). ben più complessa sembra essere invece la teoria sul più o meno generalizzato declino, fino alla completa cessazione, del fenomeno deposizionale in particolare per quanto riguarda l’olocene recente: due filoni di pensiero, talvolta in netto contrasto, associano infatti tale scomparsa, a livello globale, alternativamente a cause climatiche o antropiche (goudie, 1993). la prima corrente (geurts, 1976; preece et al., 1986) considera come causa fondamentale il progressivo raffreddamento e passaggio verso condizioni più aride (lamb, 1995) avvenuto nell’intervallo subboreale – subatlantico (periodo definito anche come “intervallo neoglaciale”) testimoniato in italia ad esempio da avanzate glaciali nelle alpi e forte instabilità climatica; tali variazioni avrebbero di conseguenza modificato anche il regime idrologico dei corsi d’acqua con conseguente crisi dei sistemi deposizionali travertinosi. una seconda teoria (nicod, 1986; vaudour, 1986; weisrock, 1986; coltorti et al., 1991) ritiene invece determinante l’importanza dell’impatto antropico sui versanti avvenuto in molte località alla fine del neolitico ed all’inizio dell’età del bronzo (fig. 9). il passaggio in questo periodo da una cultura prevalentemente nomade e pastorale, ad una di tipo agricolo e stabile e gli intensi disboscamenti operati per il reperimento di legname da costruzione e riscaldamento avrebbe innescato repentini processi di erosione della copertura pedologica; la scomparsa del suolo, principale fornitore della co2 necessaria per la dissoluzione dei carbonati, unita ad un progressivo intorbidimento delle acque per l'aumentato carico solido proveniente dai versanti ed il passaggio da un regime di flusso non molto intenso ma costante, ad uno più ingente, intermittente e canalizzato, avrebbero cancellato i requisiti necessari al prosieguo della sedimentazione travertinosa. recentemente dramis et al. (1999) hanno proposto una teoria sull’influenza delle variazioni di temperatura passate, nei sistemi acquiferi carbonatici. in particolare tali autori sottolineano l’importanza dei forti squilibri termici esistenti, all’inizio delle fasi climatiche più calde, fra le acque sotterranee (influenzate dalla “roccia serbatoio”, a più bassa conducibilità termica e quindi 269 fig. 8 schema delle caratteristiche paleoambientali del reticolo fluviale in corrispondenza delle variazioni climatiche quaternarie. sketch of paleoclimatic characteristics of the hydrographic network related to quaternary climatic variations. i travertini dell’italia centrale ... ancora in equilibrio con le condizioni “glaciali” precedenti) e le temperature esterne, che salivano molto più velocemente. tale effetto, ovviamente non esclusivo, confermerebbe il ruolo climatico, esaltando la fase deposizionale iniziale ed in parte fornendo una spiegazione al declino del processo, in relazione all’ormai raggiunto equilibrio fra le sopracitate temperature della roccia e dell’aria. fig. 9 cronologia pleistocenica ed olocenica della deposizione travertinosa. il tratto nero indica l’intervallo cronologico desunto da datazioni assolute; il tratteggio invece indica l’intervallo cronologico desunto da correlazioni geomorfologiche. pleistocene and holocene chronology of travertine deposition. black line indicates chronological interval obtained by absolute dating; dashed line indicates chronological interval obtained by geomorphological correlations. 5. conclusioni gli studi condotti sui depositi travertinosi dell’italia centrale adriatica, assieme ai dati derivanti da studi già effettuati nell’area in esame, hanno permesso di confermare come la deposizione travertinosa avvenga essenzialmente in corrispondenza di rotture del profilo dei corsi d’acqua. la crescita di questi corpi è legata soprattutto al concrezionamento su “supporti” vegetali che produce la formazione di veri e propri sbarramenti. a monte si formano piccoli bacini lacustri e/o palustri su cui sui depositano materiali fitoclastici (provenienti dalla degradazione di corpi fitoermali posti più a monte). caratteristica comune a tutti i depositi travertinosi dell’area adriatica marchigiano-abruzzese è la messa in posto in ambiente tipicamente fluviale: ➢ sia per la loro disposizione (per lo più simmetrica e parallela all’asse fluviale); ➢ sia per la presenza di frequenti strutture tipiche da trasporto; ➢ sia per gli stretti rapporti con i depositi alluvionali presenti lungo l’alveo. la presenza di diverse generazioni di depositi travertinosi disposti a quote diverse sul fondovalle attuale, la presenza alla base delle placche di travertino di clasti calcarei arrotondati di chiara origine fluviale che marcano antichi livelli di fondovalle, studi palinologici, che evidenziano come la deposizione dei travertini, nel complesso, sembra essere avvenuta in un contesto climatico tipicamente interglaciale, avvalorano l’ipotesi di come la più o meno intensa deposizione di travertino (estremamente differente anche all’interno delle stesse aree studiate, durante fasi diverse) sia da associare ad un regime idrologico che veniva mutando nel tempo. tale fenomeno, insieme al sollevamento tettonico ed alle variazioni climatiche quaternarie, sembrerebbe il maggiore responsabile della progressiva diminuzione, fino in qualche caso alla totale interruzione, della deposizione di travertino, oltre a fenomeni legati all’antropizzazione, particolarmente evidente a partire dall’olocene antico. infine, sulla base dei reciproci rapporti tra i depositi su menzionati, è stata proposta una nuova classificazione dei meccanismi deposizionali che, differentemente da quelle esistenti in letteratura, tiene conto di ambienti deposizionali e condizioni morfologiche particolari e più o meno localizzate. ringraziamenti gli autori desiderano ringraziare i referees per gli utili consigli nella revisione del testo. lavoro eseguito con fondi di ateneo dott. farabollini e prof. miccadei. il presente lavoro è frutto della ricerca e della collaborazione di tutti gli autori. in particolare farabollini p. ha coordinato la ricerca e con materazzi m. ha eseguito i rilevamenti geomorfologici e le analisi di dettaglio nell’area marchigiana e teramana e curato i modelli interpretativi; miccadei e. ha coordinato i rilevamenti geomorfologici e le analisi nell’area abruzzese; piacentini t. ha eseguito le analisi di dettaglio e i rilevamenti geomorfologici nell’area abruzzese. bibliografia bigi s., cantalamessa g., centamore e., didaskalou p., dramis f., farabollini p., gentili b., invernizzi c., micarelli a., nisio s., pambianchi g. & potetti m. 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(1975) geological summary of the central apennines. in: ogniben et al., eds. structural model of italy: maps and explanatory notes. quaderni ric. sci., c.n.r., 90, 257311. pedley h.m. (1990) classification and environmental models of cool freshwater tufas. sedimentary geology, 68, 143-154. pentecost a. (1995) the quaternary travertine deposits of europe and asia minor. quat. science review, 14, 1005-1028. pentecost a. & viles h. (1994) a review and reassessment of travertine classification. géographie physique et quaternaire, 48 (3), 305-314. preece r.c., thorpe p.m. & robinson j.e. (1986) confirmation of an interglacial age for the condat tufa (dordogne, france) from biostratigraphic and isotopic data. journal of quaternary science, 1, 57-65. preite martinez m., severa f., turi b. & fregonese d. (1990) i travertini di civitella del tronto. aspetti geochimici e giacimentologici. rend. fis. acc. lincei, ser. 9, 1, 15-24. servizio geologico d’italia (1969) carta geologica d’italia alla scala 1:100.000 foglio n.133-34 ascoli piceno giulianova. vaudorj. (1986) travertins holocène et pression anthropique. mèditerranèe, 57 (1-2), 165-167. v i o l a n t e c., d’a r g e n i o b. & f e r r e r i v. (1994) quaternary travertines at rocchetta a volturno (isernia, central italy). facies analysis and sedimentary model of an organogenic carbonate system. i.a.s. 15th reg. meet., 13-15 april 1994, ischia, guide book to the field trip, 3-23. v i o l a n t e c., f e r r e r i v. & d’a r g e n i o b. (1996) modificazioni geomorfiche controllate dalla deposizione di travertino. il quaternario, 9 (1), 213-216. weisrock a. (1986) géomorphologie et paléoenvironments de l'atlas atlantique (maroc). paris, 931 pp. z u b a k o v v.a. & b o r z e n k o v a i.i. (1990) global paleoclimate of the late cenozoic. developments in palaeontology and stratigraphy, 12, elsevier, 453 pp. 272 ms. ricevuto l’11 maggio 2004 testo definitivo ricevuto il 18 agosto 2004 ms. received: maj 11, 2004 final text received: august 18, 2004 p. farabollini et al. impaginato aprile nnuuoovvee ccoonnoosscceennzzee ssuullllaa ssttrraattiiggrraaffiiaa ee ddiissttrriibbuuzziioonnee ddeeii ddeeppoossiittii iiggnniimmbbrriittiiccii qquuaatteerrnnaarrii nneell ssoottttoossuuoolloo ddeellllaa ppiiaannaa ddeell ssaarrnnoo ((ssaalleerrnnoo--ccaammppaanniiaa)) –– iittaalliiaa mmeerriiddiioonnaallee ffrraanncceessccoo aapprriillee && rroommeeoo mmaarriiaannoo ttooccccaacceellii dip.to scienze della terra , università di napoli “ federico ii”. l.go s. marcellino,10 – 80138 napoli. tel.081/5473313. e-mail: aprile@unina.it riassunto la reinterpretazione critica di dati stratigrafici interessanti il sottosuolo della pianura del fiume sarno, costituente la parte meridionale della piana campana, ha consentito di delineare un nuovo quadro delle caratteristiche stratigrafiche dei terreni vulcanici, olocenici e pleistocenici, di riempimento della piana e in particolare dei depositi ignimbritici. in accordo con recenti studi vulcanologici è stata rilevata la presenza nel sottosuolo della piana di due livelli di tefra da flusso piroclastico; essi sono costituiti, dall’alto verso il basso, dalla ignimbrite campana (39.28±0.11 ka b.p.) presente prevalentemente nella facies del tufo grigio campano e dalla ignimbrite di taurano (157.4±1.00 ka b.p.) in facies di tufo giallo. nella zona pedemontana dei monti di sarno sono stati rinvenuti in sondaggi meccanici, al di sotto dell’ignimbrite di taurano, dei depositi marini alla quota di circa – 35 metri s.l.m. ciò dimostra l’esistenza di una ingressione marina attribuibile ad una tarda fase del pleistocene medio e quindi più antica di quella eutirreniana come finora ipotizzato. altri dati geognostici inoltre hanno portato a limitare l’estensione, nell’entroterra sarnese della suddetta trasgressione eutirreniana. e’ stata inoltre rilevata l’esistenza di una fase tettonica post 39 ka b.p. di modesta entità, che ha dislocato il tetto del tufo grigio campano senza dare luogo a manifestazioni vulcaniche come invece avvenuto nella piana campana a n del somma-vesuvio. abstract new knowledge about stratigraphy and the distribution of quaternary ignimbrite deposits in the subsurface of the sarno plain. (salerno-campania) southern italy. the critical reinterpretation of stratigraphic data concerning the subsurface of the sarno plain, located in the south part of the campania plain, has produced a new picture of the stratigraphy characteristics of the olocene and pleistocene volcanic terrains that fill the plain, in particular the ignimbrite deposits. in agreement with recent volcanological studies the presence of two pyroclastic flow deposits has been pointed out in the subsurface of the sarno plain. as a matter of fact below the campanian ignimbrite, (39.28±0.11 ky b.p.), mostly in the campanian gray tuff facies, the taurano ignimbrite, (157.4±1.00 ky b.p.), in the yellow tuff facies, occurs. in addition a modest tectonic phase dislocating the campanian gray tuff has also been pointed out. moreover this tectonic phase, in the sarno plain was not characterized by volcanic activity contrary to what happened in the campania plain northward of sommavesuvio. the recovery of marine deposits from the subsurface in the piedmont zone of sarno mountains, underlying the taurano ignimbrite at depth of 35 meters below sea level, indicates the existence of a marine trasgression older (middle pleistocene) than the eu-tyrrhenian period to which these deposits have been attribuited. this finding, in association with other geognostic and stratigraphic data, allows a reduction of the geographical extension of the eu-tyrrhenian trasgression in the sarno plain. parole chiave: piana del sarno, tettonica quaternaria, stratigrafia del sottosuolo, depositi piroclastici, depositi marini, ignimbrite campana, italia meridionale keywords: sarno plain , quaternary tectonics, subsoil stratigraphy, pyroclastic deposits, marine deposits,campanian ignimbrite, southern italy. il quaternario italian journal of quaternary sciences 1155(2), 2002, 169-174 11 - pprreemmeessssaa la pianura del fiume sarno, ubicata geograficamente a s dell’edificio vulcanico del somma-vesuvio, rappresenta la parte più meridionale della piana campana che si estende, in direzione appenninica, dal monte massico all’alto strutturale della penisola sorrentina (fig.1). studi specifici sulla piana del sarno sono stati condotti da vari autori, finalizzati prevalentemente alla conoscenza dell’evoluzione geomorfologica quaternaria (cinque et al., 1987; cinque, 1991; barra et al., 1989), dell’archeologia (albore livadie et al., 1990), dell’idrogeologia (celico et al., 1991) e del rischio ambientale (aprile et al., 1998). nel presente lavoro vengono riportati i risultati di uno studio, basato sia sull’esame di dati stratigrafici inediti che sulla reinterpretazione critica di quelli relativi a sondaggi eseguiti nel passato; tale studio mira prevalentemente a delineare la geometria dei tefra da flusso piroclastico presenti nel sottosuolo della piana del sarno, costituiti dall’alto verso il basso, dalla ignimbrite campana presente prevalentemente nella facies del tufo grigio campano e dalla ignimbrite di taurano presente nella facies di tufo giallo zeolitizzato. come è noto i livelli di materiale piroclastico, indipendentemente dai meccanismi deposizionali, rappresentano orizzonti isocroni che assumono particolare rilevanza nelle ricostruzioni paleogeografiche e stratigrafiche (narcisi, 1994). la ridatazione definitiva dei tefra della piana del sarno con metodo radiometrico (rolandi et al., 2000; de vivo et al., 2001) ha consentito quindi di acquisire anche conoscenze inedite sulla cronostratigrafia dei depositi marini connessi alle trasgressioni quaternarie. 170 f. aprile & r.m. toccaeli 22 - llaa ppiiaannaa ddeell ssaarrnnoo.. lliinneeaammeennttii ssttrruuttttuurraallii,, vvuullccaannoollooggiiccii ee ssttrraattiiggrraaffiiccii strutturalmente la piana del sarno (fig.1) costituisce il settore meridionale del vasto graben peritirrenico campano individuatosi probabilmente nel pliocene superiore (ippolito et al., 1973; aprile & ortolani, 1978; 1985) o pleistocene inferiore (cinque et al., 1987) tramite dislocazioni per faglie dirette con direzione appenninica ed antiappenninica. tali faglie hanno smembrato e ribassato il substrato carbonatico meso-cenozoico della piattaforma campano-lucana rispetto agli alti strutturali di identica litologia, che bordano la piana del sarno lungo il margine sud (m. lattari-penisola sorrentina) e ne (monti di sarno-picentini meridionali), originando uno sprofondamento a gradinata dei blocchi carbonatici a profondità crescenti dai bordi verso il centro della piana (cinque et al., 1987) ove raggiungono circa 2000 m di profondità (cassano & la torre, 1987). all’interno di tale zona ribassata è poi avvenuta una intensa aggradazione di depositi continentali, marini e vulcanici. non sono disponibili nella piana del sarno, conoscenze stratigrafiche profonde dirette tranne quelle desumibili dal pozzo geotermico trecase 1 posizionato alla quota di 220 m s.l.m sulle pendici sw del vesuvio. in tale sondaggio è stato riscontrato il basamento carbonatico a –1885 m dal p.c. (balducci et al., 1983) al di sopra del quale sono presenti depositi continentali, marini e vulcanici di varia facies, tra cui banchi di tufo grigio tra –325 e – 510 m dal p.c attribuiti alla ignimbrite campana. la struttura profonda dell’area al di sotto della potente copertura sedimentaria, è stata quindi desunta da studi geofisici. cassano & la torre (1987) con indagini gravimetriche, magnetiche e geoelettriche hanno delineato l’andamento del bedrock carbonatico, accertando inoltre la presenza di una struttura tettonica secondaria il cosiddetto graben di pompeiboscoreale ove le unità carbonatiche raggiungono il massimo approfondimento; bruno et al. (1998) rielaborando dati sismici dell’agip hanno individuato una serie di discontinuità tettoniche che confermano la complessità della struttura profonda di questa porzione del bacino eruttivo e sedimentario campano (fig. 2). correlato alle vicende tettoniche risulta essere il vulcanismo quaternario della piana del sarno comprendente sia i prodotti della ignimbrite campana che quelli del vulcanismo post ignimbritico. ai primi, recentemente ridatati con il metodo 40ar/ 39ar, è stata attribuita un’età di 39.28±0.11 ka b.p (rolandi et al., 2000; de vivo et al., 2001) e risultano presenti nel sottosuolo della piana prevalentemente nella facies del tufo grigio campano (tgc); i prodotti post ignimbritici sono costituiti essenzialmente dai depositi piroclastici del somma–vesuvio emessi durante le fasi pliniane succedutesi negli ultimi 25.000 anni e che nel sottosuolo della piana sono principalmente rappresentati (rolandi et al., 2000) dai prodotti dell’eruzione di sarno (circa 17 ka b.p.) e di ottaviano (circa 8 ka b.p.). l’ignimbrite campana con un volume stimato di circa 150 km3 (de vivo et al., 2001) costituisce il tefra da flusso piroclastico a composizione trachitica più diffuso nella regione. ancora dibattuta è la sua zona d’origine; l’ipotesi di una genesi da collasso della caldera flegrea già avanzata dal rittman (1950) e successivafig. 1 – schema geologico della piana del sarno. 1. lave ultrapotassiche del complesso vulcanico sommavesuvio; 2. flussi piroclastici, surges e lahars del complesso vulcanico somma-vesuvio; 3. depositi piroclastici ed alluvionali della piana campana; 4. unità mesocenozoiche e terziarie dell’appennino meridionale. geological scheme of the sarno plain. 1. ultrapotassic lavas of vesuvius; 2.pyroclastic flows, surges and lahars; 3.pyroclastic and alluvial deposits of campanian plain; 4. mesozoic and tertiary southern apennine formations. fig. 2 – schema strutturale della piana del sarno (da bruno et al.,1998 ridisegnata). 1. isoplete del top del substrato carbonatico (in metri s.l.m); 2. ubicazione delle faglie estrapolate da dati sismici; 3. ubicazione delle faglie interpolate da dati sismici; 4. ubicazione delle faglie da dati bibliografici; 5. graben di pompei (a) e di acerra (b). structural scheme of the sarno plain (from bruno et al., 1998 redrawn). 1. isopleths of the top of the limestone (in meters a.s.l); 2. fault location extrapolated fron seismic data; 3. fault locltion interpoled from seismic data; 4. fault location based on bibliography; 5. graben of pompei (a), graben of acerra (b). mente ripresa da rosi & sbrana (1987) si contrappone a quella avanzata da di girolamo (1968;1970), da barberi et al. (1978), da di girolamo et al. (1984) e da lirer et al. (1987) che ammettono un’origine da sistemi di fratture regionali lungo il bordo settentrionale dei campi flegrei. ancora scandone et al. (1991) ipotizzano un collasso calderico posizionato sulla depressione di acerra a ne di napoli (fig.1); quest’ultima origine viene però esclusa da bruno et al. (1998). rolandi et al. (2000) e de vivo et al. (2001) hanno rilevato sul versante orientale dei monti di sarno,in località taurano,la presenza,in affioramento (figg.1-4), di una più antica formazione ignimbritica,denominata ignimbrite di taurano. quest’ultima si presenta in facies di tufo giallo zeolitico, con tessitura massiva e matrice cineritica compatta, datato con il metodo 40ar/ 39ar 157.4±1.00 ka b.p. a questo più antico tefra che, secondo rolandi et al. (2000), è presente in tutto il sottosuolo della piana è stato dato il nome di tufo giallo di taurano (tgt). questi due depositi da flusso piroclastico del tgc e del tgt, datati radiometricamente, costituiscono quindi due preziosi livelli guida per le ricostruzioni stratigrafiche quaternarie. l’evoluzione geomorfologica quaternaria della piana del sarno e della sua fascia pedemontana, le principali caratteristiche stratigrafiche dei terreni alluvionali e marini pleistocenici ed olocenici di colmamento, sono state studiate da cinque et al. (1987) e da cinque (1991); da tali studi risulta che la piana oltre ad essersi impostata strutturalmente in ritardo, rispetto al settore nord della piana campana, sarebbe poi rimasta sostanzialmente stabile tettonicamente durante il pleistocene superiore-olocene tranne una modesta subsidenza di 171nuove conoscenze sulla stratigrafia ... circa -30 metri negli ultimi 130 ka. valori di subsidenza intorno a -4÷5 m per gli ultimi 2000 anni sono stati osservati per la parte costiera della piana (albore livadie et al., 1991). oltre ad aver individuato le diverse posizioni della linea di costa dal pleistocene superiore all’attuale,cinque (1991) ha distinto nella porzione più superficiale del pacco sedimentario la presenza di depositi in facies di spiaggia correlabili ad ingressioni marine. di queste le più estese nell’entroterra sarnese risultano essere quella di età eu-tirreniana e quella di età versiliana. i sedimenti eu-tirreniani, sempre sottoposti ai prodotti dell’ignimbrite campana, si rinvengono a quote non superiori ai –25 m s.l.m e si estendono secondo cinque et al. (1987), fin sotto i rilievi bordieri dei monti di sarno. i depositi marini versiliani sono invece presenti fino alla zona di pompei-scafati a quote che vanno da alcuni metri sotto il livello del mare a circa +2 metri s.l.m. diffusa inoltre è la presenza in tutto il sottosuolo di depositi lacustri e palustri (torbe e limi) tipici degli ambienti di transizione associati sia alle predette ingressioni che a quelle di età romana e alto-mediovale 33 - ddiissccuussssiioonnee ddeeii ddaattii ee rriissuullttaattii la disponibilità dei dati di nuovi sondaggi meccanici, unitamente alla reinterpretazione critica di quelli eseguiti nel passato, di varia provenienza (da ricerche idriche, dal raddoppio linea fs, da precedenti lavori, da enti pubblici ecc..) per un totale di circa 150 pozzi, di profondità compresa tra i 30 ed i 118 metri dal p.c, ha consentito la ricostruzione, con buona accuratezza, della stratigrafia e struttura della porzione più prossima alla superficie dei terreni vulcanici quaternari. é stato quindi possibile elaborare una carta strutturale dell’andamento del tetto del tufo grigio campano (tgc). la realizzazione di due sezioni geologiche significative pone in evidenza i rapporti tra le unità litostratigrafiche presenti nel sottosuolo. per quanto riguarda l’andamento del tetto del tgc (fig.3) se ne osserva, nel complesso, un aumento progressivo della profondità procedendo dalle zone circostanti i rilievi bordieri verso il centro della piana ove, in corrispondenza del tratto mediano del fiume sarno, coincidente grosso modo con il punto di massimo sprofondamento del graben, raggiunge una profondità di circa –30 metri s.l.m. l’esame delle sezioni geologiche (figg. 4 e 5) restituisce un quadro completo ed inedito della situazione stratigrafica del sottosuolo della piana del sarno. la prima considerazione risulta essere che il substrato portante dello spessore di terreni indagati è costituito dal banco di tgc che, con la sua deposizione, ha praticamente appiattito la precedente morfologia del tufo giallo di taurano. nella sezione di fig. 4 il tetto del tgc, posto ad una profondità compresa tra +10 metri e -30 m s.l.m presenta un andamento generale, dai monti di sarno verso w, immergente gradatamente verso il centro della piana. dalla località messigno in poi il tgc sembra scomparire; tale mancato rinvenimento, come in altre zone della piana, è da addebitare alla limitata profondità d’indagine dei sondaggi in zona; del resto già cassano & la torre (1987) in base ai dati geofisici prolungano la presenza del tgc fino alla costa. analogo andamento denota il tgc nella fig.5 fig. 3 – isoplete del tetto del tufo grigio campano ed ubicazione sondaggi. 1. isoplete del top del tufo grigio campano (in metri s.l.m); 2. sondaggi meccanici; 3. traccia sezione geologica (a-a; b-b; delle figg. 4 e 5). isopleths of the top of campanian gray tuff and location of boreholes. 1. isopleths of the top of campanian gray tuff (in meters a.s.l.); 2. location of boreholes; 3. cross-section marks (a-a; b-b; of figg. 4 and 5); 172 f. aprile & r.m. toccaeli ove esso si presenta con due bancate, provenienti rispettivamente dai monti di castellammare e da sotto l’edificio del somma-vesuvio, che si immergono verso il centro della piana. inoltre in direzione dell’edificio vulcanico del somma-vesuvio si evidenzia una marcata flessura, controllata presumibilmente da strutture disgiuntive, del corpo ignimbritico il cui tetto nel pozzo trecase 1 si posiziona a circa –100 m s.l.m. altro elemento caratterizzante la morfologia del tgc è costituito dalla dislocazione del top con dislivelli dell’ordine di qualche decina di metri. queste soluzioni di continuità nell’andamento del tetto del tgc è l’espressione di una attività tettonica post 39 ka b.p. coeva a quella già individuata nella piana campana a nord del somma-vesuvio (aprile et al.,1992). tale tettonica, successiva alla deposizione del tgc, sembra però avere caratteri meno marcati rispetto a quella a nord del somma-vesuvio sia per la minore entità delle dislocazioni che per la mancanza di prodotti vulcanici all’interno ed al di sopra del tgc. questi ultimi prodotti, costituiti da scorie e brecce laviche, con caratteristiche evolventi verso flussi piroclastici, risultano invece presenti nella parte nord della piana campana e sono stati interpretati come dovuti a manifestazioni ignimbritiche più recenti (circa 20 ka b.p.) causate dalla riattivazione dei sistemi di fratture correlati alle fasi ignimbritiche più antiche (rolandi, 1988; aprile et al., 1992). dall’esame della fig.4 in corrispondenza dei sondaggi meccanici più profondi (ssml6, ssml9, fs136, fs137, sm3, sm2, sm1) si nota, inoltre, la presenza di un altro tefra, separato dal sovrastante tgc da un livelfig. 4 sezione geologica schematica a-a: monti di sarno – foce del sarno. 1. depositi di spiaggia ed eolici attuali e recenti; 2. depositi alluvionali e piroclastiti subaeree (in posto e/o rimaneggiate) recenti del somma -vesuvio( a.d. 79 1944); 3. detriti di falda e di versante s.l.; 4. depositi litorali e di spiaggia con livelli di torba del “complesso versiliano” (olocene); 5. depositi palustri e lagunari associati al “complesso versiliano” (olocene); 6. depositi alluvionali e piroclastiti in posto o rimaneggiate; principalmente attribuibili alle eruzioni di sarno e ottaviano (17 ka e 8 ka b.p.); 7. tufo grigio campano (circa 39 ka b.p.); 8. tufo giallo di taurano (circa 157 ka b.p.); 9. depositi di spiaggia e marini tardo pleistocene medio; 10. termini calcareo-dolomitici mesozoico-terziari; 11. faglia presunta; 12. faglia. schematic geological cross section a-a: mountains of sarno mouth of the sarno river 1. beach and eolian recent deposits; 2. alluvial deposits and recent subaerial pyroclastic products (in situ or reworked) of somma-vesuvius (a.d. 79 1944); 3. talus and slope deposits; 4. beach and shore sediments with peat levels of the versilian complex; 5. palustrine and lagoonal deposits of the versilian complex; 6. alluvial deposits and undisturbed or reworked pyroclastic deposits of sarno (17 ky b.p.) and ottaviano (8 ky b.p.) eruptions principally; 7. campanian gray tuff (about 39 ky b.p.); 8. taurano yellow tuff (about 157 ky b.p.); 9. beach and marine deposits (late middle pleistocene); 10. dolomites and limestones (mesozoic cenozoic); 11. presumed fault; 12. fault. 173nuove conoscenze sulla stratigrafia ... lo di paleosuolo e di pomici basali.tale formazione si rinviene nel sottosuolo con una notevole estensione areale compresa, tra i rilievi bordieri di sarno fin oltre s. marzano, con una profondità del tetto compresa tra –16 e –30 metri s.l.m; la facies di questo banco da flusso piroclastico è quella di un tufo giallo zeolitico con le stesse caratteristiche petrografiche del tufo giallo di taurano rinvenuto in affioramento (rolandi et al., 2000; de vivo et al., 2001). l’identità nelle caratteristiche petrografiche insieme alla sua posizione stratigrafica (sempre a letto del tgc con paleosuolo e pomici basali interposte) porta quindi a correlare cronostratigraficamente questo tefra con il tufo giallo di taurano (tgt) datato a circa 157 ka b.p. le articolazioni nell’andamento del top del tgt risultano presumilmente dovute ad un modellamento per erosione in ambiente continentale come testimoniato dalla presenza a tetto del paleosuolo. altro dato inedito è il rinvenimento di depositi marini alla profondità di circa –35 m s.lm, al letto del tufo giallo di taurano, in corrispondenza di sondaggi meccanici profondi (ssml6 e ssml9), ubicati sul piedimonte dei monti di sarno (nicotera & civita, 1969). data la loro posizione stratigrafica tali depositi devono essere più antichi di 157 ka b.p; questa constatazione riferita alla cronologia della stratigrafia isotopica marina (williams et al., 1998) consente di attribuire tali sedimenti ad una tarda fase trasgressiva del pleistocene medio, e non a quella eutirreniana cui, come ipotizzato da cinque et al. (1987), tali depositi dovrebbero appartenere. inoltre la totale assenza di depositi marini, al letto del tgc, nei sondaggi esaminati, nel tratto monti di sarno–san marzano (fig.4), porta a ritenere che l’ingressione eutirreniana si sia estesa nell’entroterra non fino ai rilievi bordieri più interni della piana di sarno, ma al più fino alla zona compresa tra scafati e san marzano. fig. 5 sezione geologica schematica b-b: vesuvio – monte pendolo. 1. depositi alluvionali e piroclastiti subaeree (in posto e/o rimaneggiate) recenti; 2. detriti di versante s.l.; 3. depositi di spiaggia ed eolici del “complesso versiliano”; 4. depositi di spiaggia e litorali con livelli di torba del “complesso versiliano”; 5. depositi di conoide alluvionale e coni di deiezione (tardoolocene); 6. depositi alluvionali (tardo-pleistocene); 7. alluvioni post tufo grigio campano del conoide di “scanzano” (pleistocene superiore); 8. piroclastiti e lave dell’edificio vulcanico del sommavesuvio; 9. ignimbrite campana (circa 39 ka b.p.); 10. depositi del conoide di “gragnano” e coni di deiezione più recenti (pleistocene superiore); 11. tufo giallo di taurano (circa 157 ka b.p.); 12. depositi di spiaggia e marini (tardo pleistocene medio); 13. termini calcareo-dolomitici (mesozoico-terziario); 14. faglia presunta; 15. faglia . schematic geological cross section b-b: vesuvius – pendolo mount. 1. alluvial deposits and recent subaerial pyroclastic products (in situ or reworked) of somma-vesuvius (a.d. 79 – 1944); 2. talus and slope deposits; 3. beach and recent aeolian deposits; 4. beach and shore sediments with peat levels of the versilian complex (olocene); 5. late holocene alluvial fans and debris cones deposits; 6. late pleistocene alluvial fans; 7. “scanzano” alluvial fan deposits (upper pleistocene); 8. lavas and pyroclastic products of somma-vesuvius complex; 9. campanian gray tuff (about 39 ky b.p.); 10. “gragnano” alluvial fan deposit and recent alluvial or debris cones deposits (upper pleistocene); 11. taurano yellow tuff (about 157 ky b.p.); 12. beach and marine deposits (late middle pleistocene); 13. dolomites and limestones (mesozoic cenozoic); 14. presumed fault; 15. fault. 174 f. aprile & r.m. toccaeli 44 - ccoonnssiiddeerraazziioonnii ccoonncclluussiivvee lo studio del sottosuolo della piana del sarno ha messo in evidenza aspetti in gran parte inediti che possono riassumersi come segue: presenza in larga parte del sottosuolo della piana del sarno di due distinti tefra ignimbritici sovrapposti ,di cui il superiore, datato 39.28 ± 0.11 ka b.p risulta costituito dalla ignimbrite campana in facies di tufo grigio campano e quello inferiore, datato157.4±1.00 ka b.p risulta costituito dalla ignimbrite di taurano in facies di tufo giallo attribuzione ad una tarda fase ingressiva del pleistocene medio e non all’ingressione eutirreniana, come fino ad oggi proposto, dei depositi marini rinvenuti, a letto del tufo giallo di taurano, nei sondaggi situati sul piedimonte dei monti di sarno probabile riduzione dell’estensione nell’entroterra sarnese dell’ingressione marina eutirreniana conferma dell’esistenza di una modesta attività tettonica nella piana del sarno, post 39 ka b.p. con caratteri meno marcati rispetto a quella coeva e di maggiore intensità avvenuta nel settore della piana campana a n del somma-vesuvio llaavvoorrii cciittaattii albore livadie c., barra d., bonaduce g., brancaccio l., cinque a., ortolani f.,pagliuca s. & russo f. 1990 evoluzione geomorfologica,neotettonica e vulcanica della pianura costiera del fiume sarno (campania) in relazione agli insediamenti anteriori all’eruzione del 79 d.c. vulcanol. et archeol., 2255, 237-256. aprile f. & ortolani f. 1978 nuovi dati sulla struttura profonda della piana campana a sud est del fiume volturno. boll. soc. geol. it., 9977,591-608. aprile f. & ortolani f. 1985 principali caratteristiche stratigrafiche e strutturali dei depositi superficiali della piana campana. boll. soc. geol. it., 110044,195-206. aprile f., castaldi v., ortolani f., pagliuca s. & rolandi g. 1992 tettonica e vulcanismo negli ultimi 35.000 anni nella piana campana. atti 1111° convegno g.n.g.t.s. roma, 9 – 11 dic.1992, 425-429. aprile f., ortolani f. & toccaceli r. 1998 proposta di restauro geoambientale della piana del sarno (sa). geologia tecnica & ambientale. n° 22, 31-38. balducci s., vaselli m. & verdiani g. 1983 – exploration well in the ottaviano permit, italy, trecase 1. eur. geot. update, 33rrdd intern. sem., munich, 29 nov.1 dic., 407-418. barberi f., innocenti f., lirer l., munno r., pescatore t. & santacroce r. 1978 – the campanian ignimbrite: a major prehistoric eruption in the neapolitan area (italy). bull.volcanol. 4411(1), 1-22. barra d., bonaduce g., brancaccio l., cinque a., ortolani f., pagliuca s. & russo f. 1989evoluzione geologica olocenica della piana costiera del fiume sarno. mem. soc. geol. it. 4422, 255-267. bruno g., cippitelli g., rapolla a. 1998 seismic study of the mesozoic carbonate basament around mt. somma – vesuvius, italy. journal of volcanology and geothermal research 8844, 311-322. cassano e. & la torre p. 1987 geophysics in somma-vesuvius. quaderni della ricerca scientifica, cnr, 88,175-196. celico p., malafronte a. & piscopo v. 1991 bilancio ideologico e idrodinamica della piana del sarno (sa). i° convegno naz. giovani ricercatori in geologia appl.suppl. n. 9933, 297-306 . univ. studi di milano. gargnano (bs), 22-23 ottobre 1991. cinque a., alinaghi h.h., laureti l. & russo f. 1987 osservazioni preliminari sull’evoluzione geomorfologia della piana del sarno. (campania, appenino meridionale). geogr. fisica e dinamica quaternaria, 1100,161 – 174. cinque a. 1991la trasgressione versiliana nella piana del sarno (campania). geogr. fisica e dinamica quaternaria, 1144, (1), 63-71. de vivo b., rolandi g., gans p.b., calvert a., bohrson w.a., spera f.j., h.e. 2001 -new constraints on the pyroclastic eruptive history of the campanian volcanic plain ( italy). mineralogy and petrology,7733, (1-3), 47-65. di girolamo p.1968petrografia dei tufi campani: il processo di pipernizzazione (tufo-tufo pipernoide-piperno). rend.acc.sc.fis.matem. in napoli. serie 44, xxxv, 1-70. di girolamo p.1970 differenziazione gravitativa e curve isochimiche nella ignimbrite campana. rend. soc. it. mineral.petrol. 26 (22), 547-588. di girolamo p., ghiara m.r., lirer l., munno r ., rolandi g. & stanzione d. 1984 vulcanologia e petrologia dei campi flegrei. boll. soc. geol. it., 110033, 349-413. ippolito f., ortolani f., & russo m. 1973 struttura marginale tirrenica dell’appennino campano: reinterpretazione di dati di ricerche di idrocarburi. mem.soc.geol.it.,1122, 228-249. lirer l., luongo g., scandone r. 1987 on the volcanological evolution of campi flegrei. eos, trans. am. geophys. union, 6688, 226-334. narcisi b. 1994 tefracronologia in aree non vulcaniche: principi, metodi di indagine e stato dell’arte nel contesto italiano. il quaternario, 7, (2), 545-554. nicotera p. & civita m. 1969 indagini idrogeologiche per la captazione delle sorgenti di s.marina (sarno). mem. ist. geol. appl. napoli, 1111, 25-44. rittman a.1950 sintesi geologica dei campi flegrei. boll. soc. geol. it., lxix(iiii),117-128. rolandi g.1988 – le ignimbriti della piana campana. atti 74° congresso soc.geol.it., bb, 350-352 rolandi g., bertollini f., cozzolino g., esposito n., sannino d. 2000 sull’origine delle coltri piroclastiche presenti sul versante occidentale del pizzo d’alvano ( sarno – campania ). quaderni di geologia applicata , 77 – 1, 37-47. rosi m. and sbrana a. (editors),1987 the phlegrean fields. quaderni della ricerca scientifica, cnr, 111144, 9,175. scandone r., bellucci f., lirer l.& rolandi g. 1991 the structure of the campanian plain and the activity of the neapolitan volcanoes (italy). j. volcanol. geotherm. res. 4488,1-31. williams d.f., thunell r.c., tappa e. & raffi i. 1998 chronology of the pleistocene oxygen isotope record. 0-1.88 m.y b.p. palaeogeogr. palaeoclim. palaeocol., 6644, 221-240. ms. ricevuto il 19 febbraio 2002 testo definitivo ricevuto il 25 giugno 2002 ms. received: february 19, 2002 final text received: june 25, 2002 imp.narcisi qquuaatteerrnnaarryy ddiissttaall tteepphhrraa llaayyeerrss iinn iittaallyy aanndd tthhee aaddjjooiinniinngg sseeaass:: ccuurrrreenntt kknnoowwlleeddggee aanndd pprroossppeeccttss ffoorr ffuuttuurree rreesseeaarrcchh bbiiaannccaammaarriiaa nnaarrcciissii enea c.r. casaccia, c.p. 2400, 00100 roma, italy narcisi@casaccia.enea.it abstract tephrochronological studies on quaternary sedimentary successions of the central mediterranean area are reviewed and critically evaluated, with emphasis on the use of distal ash layers for land-sea correlations. the longest tephra records are provided by the deep-sea sediments from the basins adjoining italy, which have been extensively studied in the last 30 years. shorter (<100 ka), yet still significant records of ash layers have been recovered in lacustrine basins of the italian peninsula. the longest successions show that the tephra layers increase toward the top of the quaternary record. the dominant pliocene and lower pleistocene tephra sources were likely represented by the volcanoes of the pontine islands and the aeolian arc, while in the middle-upper pleistocene and holocene times aeolian and campanian products have been predominant. tephra correlation is made difficult by the fact that the volcaniclastic products are extensively reworked by epiclastic processes, even in the marine setting. inconsistent analytical approaches used in the old and recent work (bulk sample versus grain-discrete analysis) hinder integration of the available evidence. the regional tephrostratigraphy of early and middle pleistocene ages is not established yet, because data are scarce and fragmentary and ages of tephra are poorly defined. tephra correlation is frequent in the late quaternary time span, in which several widespread marker-tephras have been identified. recent findings extend the known distribution of the main late pleistocene markers and suggest complex dispersal patterns, including deposition towards north and northeast. occurrence of quaternary tephra layers of probable italian origin in sites of central and eastern europe opens the prospect for precise correlation of sedimentary records across the european continent. finally, reliable linking of chemical spikes in north polar records to italian explosive eruptions could be critical for a better understanding of palaeoenvironmental issues. riassunto tephra distali quaternari in italia e nei mari adiacenti: stato delle conoscenze e prospettive di ricerca. questo lavoro prende in rassegna gli studi tephrocronologici effettuati sulle sequenze sedimentarie dell’area centro-mediterranea ed effettua una sintesi delle conoscenze disponibili, particolarmente per quanto concerne le informazioni utili per correlazioni fra successioni marine e successioni continentali. le tephro-sequenze più rilevanti per continuità stratigrafica ed estensione temporale riguardano i sedimenti di mare profondo, i quali sono stati diffusamente campionati e analizzati nel corso degli ultimi 30 anni. in ambiente continentale, i risultati più significativi provengono dallo studio di lunghe sequenze lacustri dell’italia peninsulare, campionate per indagini paleoclimatiche. i dati delle sequenze più lunghe indicano che i livelli piroclastici aumentano nel quaternario superiore. relativamente alle sorgenti vulcaniche, durante il pliocene ed il pleistocene inferiore prevalgono prodotti dei vulcani delle isole pontine e dell’arco eoliano, mentre nel pleistocene mediosuperiore e nell’olocene sono preponderanti i prodotti eoliani e quelli campani. la correlazione tra livelli di tephra, compresi quelli contenuti nelle sequenze di ambiente marino profondo, è complicata dal rimaneggiamento del materiale piroclastico. la disomogeneità dei dati analitici, soprattutto di quelli relativi alla composizione geochimica del materiale piroclastico, non consente di integrare i risultati pubblicati di recente con quelli dei vecchi lavori. a causa dell’esigua disponibilità di osservazioni e delle scarse informazioni sull’inquadramento cronostratigrafico degli orizzonti piroclastici, non è stata ancora definita la tephrostratigrafia regionale per i periodi più antichi del quaternario. la correlazione dei livelli di tephra è invece frequente nel pleistocene superiore, nel quale sono stati individuati alcuni livelli guida per accurate correlazioni stratigrafiche fra successioni marine e continentali. sulla base di nuovi ritrovamenti, la distribuzione areale di alcuni di questi livelli risulta alquanto complessa e comprende la dispersione anche verso i quadranti settentrionali. recenti segnalazioni di tephra di probabile origine italiana in successioni continentali dell’europa centrale aprono la prospettiva di future correlazioni su scala continentale. infine, la corrispondenza tra alcuni segnali geochimici nelle carote di ghiaccio del polo nord ed eruzioni esplosive italiane, tuttora da dimostrare, potrebbe contribuire alla soluzione di importanti quesiti paleoclimatici. keywords: airfall tephra, deep-sea cores, long-distance correlation, quaternary, italy, central mediterranean parole chiave: piroclastiti di caduta, carote di mare profondo, correlazione, quaternario, italia, mediterraneo centrale. il quaternario italian journal of quaternary sciences 1166(1bis), 2003, 3-9 iinnttrroodduuccttiioonn compiling of an exhaustive review on quaternary airfall tephra layers in the central mediterranean area is an arduous task, due to the massive published information pertaining to this topic. suffice it to mention that the first record of the greek term “tephra” (τεφρα) for volcanic ash, dated back to about 360 b.c., concerns just a central mediterranean explosive eruption, whose account was made by aristotle in his book meteorologia. thus, while the modern term “tephrochronology” is less than 60 years old (in thorarinsson, 1974), bibliography on mediterranean tephra spans over two and half millennia of naturalistic and historical literature. even when focusing on the geoscientific bibliography of the last decades, and excluding findings in the proximal setting (< 50 km from source), reports on quaternary volcaniclastic deposits in the central mediterranean sediments are exceptionally numerous. attempts to collect all the published documentation are hampered by the fact that it is dispersed through literature of disciplines as diverse as geoarchaeology, marine micropalaeontology, palynology, stable isotope geochemistry and sedimentology. although publications are so numerous, a part of the published information is not suitable for the development of the quaternary regional tephrostratigraphy. in 4 b. narcisi fact in many cases reports of tephra deposits are not provided with appropriate laboratory data for characterisation of the volcaniclastic material, or fail in reporting details on the used analytical methods. in other cases tephra reworking is either apparent or not properly considered, or the chrono-stratigraphical framework of the tephra and of the tephra-bearing deposits is poorly defined. despite the aforementioned problems and limitations, a few contributions have been published that aim at reviewing the main evidence for quaternary distal tephra layers in the mediterranean region (keller, 1981a; narcisi & vezzoli, 1999) and the italian context (narcisi, 1994) or at collecting systematically data on volcaniclastic deposits in the apennine region (guerrera & veneri, 1989). the present paper represents advancement and updating of the previous reviews carried out by the author. in particular, it is intended to focus on the published tephra information that is of interest for correlation between continental and marine successions. in addition, a few case studies of widely dispersed italian tephra layers are presented and prospects for future research in the field of long-distance correlations are outlined. tthhee pprriinncciippaall aavvaaiillaabbllee ddaattaa marine successions the most significant tephra records of the central mediterranean region, in terms of stratigraphic continuity, ash preservation and time span, are provided by the abyssal sediments. since the late 1940’s several deep-sea investigations have been carried out in the frame of international drilling programs and national enterprises (fig. 1). tephra studies have often been associated with micropalaeontological, sedimentological, stable isotope and magnetic investigations, and radioisotope dating of fossil shells, providing the chronostratigraphic framework of the recorded ash layers. very recently, direct isotopic datation has been attempted on marine ash layers from tyrrhenian core sequences (bogaard et al., 1999; ton-that et al., 2001). due to the difficulty of recovering long records, information on the early pleistocene tephra layers in deep-sea cores is rather sparse. the longest successions, extending back up to miocene, have been retrieved within the deep sea drilling project/ocean drilling program (dsdp/odp), which has dedicated several cruises (i.e. legs 13, 42, 107, 160 and 161) to the central mediterranean area (fig. 1). in addition to the dsdp/odp cores, many shorter, but still important tephra records are available from the tyrrhenian (e.g. paterne et al., 1986; 1988), the adriatic (calanchi et al., 1998), and the ionian seas (keller et al., 1978). from the analysis of the most significant records some general trends can be traced, both in time and in space. the content of volcaniclastic material increases toward the top of the quaternary succession. although each core shows its own tephrostratigraphy reflecting the dominance of the closest tephra source, the data acquired in the recent odp cruises performed in the tyrrhenian sea (mccoy & cornell, 1990; calanchi et al., 1994; bogaard et al., 1999) show that the dominant pliocene and lower pleistocene tephra sources were likely represented by the volcanoes of the pontine islands and the aeolian arc, while in the middle-upper pleistocene and in the holocene aeolian and campanian products were the most frequent. the content of volcaniclastic material in each core depends on the distance of the coring sites from the volcanic sources and on the influence by subaerial (i.e. transport of ash particles by dominant winds) and subaqueous (i.e. reworking before the final deposition) physical agents. indeed, the role of reworking of volcaniclastic sediments in tyrrhenian pelagic records had been emphasized by the earlier studies on cores collected in the abyssal plain (e.g. bartolini et al., 1974). recently, detailed sedimentological and geochemical investigations on odp core sequences have clearly demonstrated that tephra layers originating from ash fallout are rare in the tyrrhenian sea; remobilisation of pyroclastic material by turbidite currents and debris flows is a common phenomenon and it may lead to significant displacement of the tephra from its original stratigraphic position (mccoy & cornell, 1990; calanchi et al., 1994; bogaard et al., 1999). erosion of the thinner layers by sea-bottom currents and bioturbation may represent further factors influencing the record of tephra fall layers. in fig. 2 striking differences can be observed in the frequency of primary tephras, up to one order of magnitude, in late quaternary tyrrhenian cores drilled in close sites with comparable physiographic conditions, as is the case of figure 1 map of the central mediterranean showing the location of quaternary volcanoes (triangles) and seamounts (stars), and of significant deep-sea tephra records. core ket8004 (paterne et al., 1988) and odp site 650 sequence (mccoy & cornell, 1990). these differences may be due to the different sampling resolution or may reflect different constraints applied by the various investigators on the definition of a “non-reworked tephra”. integrating the recent deep-sea findings with evidence from old coring would certainly increase knowledge of stratigraphy and areal distribution of mediterranean ash layers. however, attempts to collate these data are hindered by inconsistent methodological approaches (narcisi & vezzoli, 1999). specifically, the earlier investigations were mainly descriptive; the few geochemical data presented were obtained from wholerock analysis and are clearly influenced by weathering of the volcanic material and contamination by detrital clasts (see for example nesteroff et al., 1973). in the recent tephra studies, bulk sample analysis has been fully replaced by grain-discrete electron microprobe (emp) analysis. due to these differences, few correlations can be attempted between the central mediterranean tephrostratigraphy, resting on emp data, and the well-defined tephra framework of the ionian and levantine seas (keller et al. 1978), which was developed in the late 1970’s on the basis of bulk analysis. reports of findings of tephra in terrestrial exposures of marine sediments are numerous. in southern peninsular italy, some volcaniclastic layers have origin from the nearby vulture volcano (ciaranfi et al., 1996) while others derive from more distant sources (spadea, 1986). in this region, marine ash layers have been 5quaternary distal tephra layers ... extensively used for local correlation purposes (ciaranfi et al., 2001), for reconstruction of the magmatic evolution of the pleistocene volcanism (cello et al., 1983; spadea, 1986), and for inferring relationship between volcanism and tectono-sedimentary processes (cortesogno et al., 1984). some layers have been subject to direct dating (obradovich et al., 1982). petrographic and mineralogical evidence suggests that only few pyroclastic layers are coeval to deposition of bracketing sediments and/or are free from weathering (d’elia et al., 1987). continental successions compared with the deep-sea records, land sequences of tephra are less significant due to intensive erosion and reworking processes acting on the continental realm. in italy, the best continental successions of ash layers are provided by the lacustrine sediments, which have extensively been studied in the last two decades for palaeoclimatic purposes (calanchi et al., 1996; karner et al., 1999; narcisi, 1996; 2002). results worthy to be mentioned have been obtained also on other clastic sequences (narcisi, 1993; bigazzi at al., 1994) and on volcanic palaeosols and related parent materials (frezzotti & narcisi, 1996). cases of direct datation of continental ash layers are common (e.g. bigazzi et al., 1994; 2000; karner et al., 1999). the findings of continental ash layers so far published are almost exclusively located in peninsular italy. to some extent, this distribution reflects proximity of the sites to the explosive volcanic sources; certainly, it is strongly influenced by non-uniform surveying. in fact, entire continental sub-regions that most probably were repeatedly blanketed by ash fallout during the quaternary, are still unexplored from the tephra point of view. similarly, knowledge on land distribution of the identified ash markers is still very patchy as it is defined by casual findings rather than by geographic systematic studies. consequently, an unequivocal and continuous quaternary reference stratigraphy of the distal tephras in the various land regions is still lacking. lloonngg--ddiissttaannccee ccoorrrreellaattiioonn aanndd wwiiddeellyy ddiissppeerrsseedd tteepphhrraa llaayyeerrss in the older quaternary record, correlations of individual tephra layers from marine cores have been achieved in a limited number of cases (cita et al., 1973; bogaard et al., 1999). in theory, regional-scale correlation of tephra in early pleistocene records would be facilitated by the fact that ash layers in this period are not so abundant as in the late quaternary (cita et al., 1973; calanchi et al.., 1994). in practice, identification of older marker tephras is made difficult by the scarce and fragmentary available information, and by uncertainties in the age of the tephra. thus, although chemical and mineralogical features of the 0.6 ma tephra occurring in tuscan continental deposits (nencini, 1983; bigazzi et al., 1994) resemble those of two middle pleistocene ash layers encountered at the tyrrhenian dsdp site 373 (ssp, 1978; keller, 1981a), their correlation cannot be demonstrated because the age of these marine layers is poorly constrained. besides, whilst generic comparison between deep-sea ash layers and volcaniclastic depofigure 2 frequency of recorded primary tephra layers (per 1000 years) in selected late quaternary deep-sea records of the central mediterranean. data of frequency have been calculated from the tephra information reported in cita et al. (1973); keller et al. (1978); keller (1981b); paterne et al. (1988); fontugne et al. (1989); mccoy & cornell (1990); kallel et al. (1997); calanchi et al. (1998). 6 b. narcisi sits in land exposures can be attempted (e.g. calanchi et al., 1994), correlation of specific tephra horizons is more difficult. as an example, on the basis of the sapropel correlation proposed by de kaenel et al. (1999) and of biostratigraphic and palaeomagnetic evidence, the chrono-stratigraphic position of ash turbidite vt-7539/vt7538 from tyrrhenian odp site 974 (bogaard et al., 1999) matches well that of the ash layer m at vrica, southern italy (selli et al., 1977; pasini & colalongo, 2001). according to spadea (1986) and bogaard et al. (1999) both tephras can be classified as high-k rhyolite; close analysis of the data however reveals significant mineralogical and geochemical differences that make correlation between these two layers problematic. while there are few identified early and middle pleistocene marker-tephras (bogaard et al., 1999) and consequently correlation among sites is rarely attained, tephra correlation becomes frequent when late quaternary records are considered (paterne et al., 1986; 1988; narcisi, 1996; calanchi et al., 1998). identification of marker-tephras in this time interval is facilitated by both preservation of deposits and more rigorous age control. main features and chronology of the principal distal tephras of the last 200,000 years are reported elsewhere (narcisi & vezzoli, 1999). recent advances in the knowledge of some late pleistocene tephra markers are worthy to be mentioned in this contribution. layer y-5 – the most widespread tephra layer of the mediterranean related to the eruption of the campanian ignimbrite from the phlegraean fields area – has recently been the subject of radiometric assay (ton-that et al., 2001). ar/ar analysis of sanidine crystals from this layer cored in the tyrrhenian abyssal plain (site ket8004) indicate a most probable age of 41 ka, which is at least 2-3 ka older than estimates on both proximal land exposures (deino et al., 1992; de vivo et al., 2001) and the distal ash in marine and lacustrine cores (thunell et al., 1979; narcisi, 1996; watts et al., 1996). the presence into the dated tephra layer of crystal populations older than 41 ka deserves notice. in marine cores collected not far from ket8004 this campanian marker is represented by a few metres-thick volcaniclastic debris flow comprising vitric particles of heterogeneous origin and also shallow-water mollusc shells (mccoy & cornell, 1990; calanchi et al., 1994; cini castagnoli et al., 1995). however, ton-that et al. (2001) reject a turbiditic origin of the dated tephra and opt for mixing of xenocrysts into the juvenile ash fraction to explain the observed age heterogeneity. currently, the areal distribution of y-5 is defined by some hundred of recovery sites, mainly related to the eastern mediterranean marine setting (fig. 3 of narcisi & vezzoli, 1999); however, a broader, and more complex dispersal is strongly suggested by occurrence in eastern europe of a tephra layer with age and composition similar to y-5 (melekestzev et al., 1984). surprisingly, this tephra has not been recovered or identified in the newly studied piston cores drilled in the eastern mediterranean within the known y-5 dispersal area (clift & blusztajn, 1999). given its wide distribution, speculations have been made on the potential interference of the y-5 related eruption with the mediterranean ecological and social system (fedele et al., 2002). increasing attention has recently been deserved to the two marker-tephras that characterise the tephrostratigraphy of the lateglacial period. recent findings of the older marker y-1 (et-1 according to paterne et al., 1988) extend the areal distribution of this tephra far beyond the previously recognised dispersal. in fact, current knowledge indicates that this marker, which is related to the 14 uncal. ka etna multiple eruption that produced the ellittico caldera collapse (coltelli et al., 2000), is distributed towards southeast in the eastern mediterranean and towards north in central italy and adjoining seas (narcisi, 1999a). new occurrences of the younger marker c-2 dated 12.5 uncal. ka and related to the neapolitan yellow tuff from the phlegraean fields area (scarpati et al., 1993), have enabled to trace with more confidence its dispersal area. findings in central italy and in the tyrrhenian and adriatic seas suggest a north-easterly distribution (narcisi, 1999b) and the recent discovery of a lateglacial tephra correlated on geochemical grounds to c-2 in lacustrine records of the northern apennines (davies et al., 2002) and in austria (schmidt et al., 2002) confirms this pattern besides extending significantly dispersal of this tephra. while earlier studies in the mediterranean showed an overall south-easterly ash dispersal ascribed to supposed persistent north-westerly palaeowind directions over the last 200,000 years (mccoy, 1980), the presented examples, together with increasing findings in very remote european sites (see below), suggest that some italian airfall tephra layers might have complex distribution patterns, including also dispersal towards north and northeast. support of evidence of northward aeolian dust transport is provided by recent palynological studies that have pointed out the significance over the western mediterranean of air masses coming from the south, at least during the upper pleistocene and holocene (magri & parra, 2002). previously reconstructed south-easterly distribution of mediterranean tephra might, at least in some cases, be an artefact due to inadequate surveying and non-uniform spatial distribution of sampling sites. ccoonncclluuddiinngg rreemmaarrkkss aanndd pprroossppeeccttss ffoorr ffuuttuurree rreesseeaarrcchh distal tephra layers are powerful tools for unambiguous linking of sites from different environmental settings, and across regions and even continents. the central mediterranean represents one of the most suitable regions of our planet for quaternary tephra investigations, due to the following features (fig. 1): a) abundance of volcanic sources that are quite scattered over the whole region, b) occurrence throughout the quaternary of large-scale explosive volcanism producing significant pyroclastic sheets, c) favourable location of the volcanoes in relation to the land-sea distribution, enabling distal ash fallout to involve simultaneously marine and continental environments, d) marked differences in geochemical signatures from province to province (peccerillo, 2001) that make it possible to discriminate among tephra sources. on the whole, knowledge of quaternary distal tephra in italy has advanced significantly over the last two decades. however, the potential for establishing a detailed tephrostratigraphy is not fully exploited yet. 7quaternary distal tephra layers ... stratigraphical and analytical problems remain in some reports. integration of stratigraphic data with radiometric and palaeomagnetic information is recommended for future work. in addition, more rigorous protocols of characterisation of the identified tephra horizons should be applied, including careful investigation of sedimentary features and detailed microstructural, petrographic and petrochemical studies (westgate & gorton, 1981). in addition to studies on future tephra records, re-examination of ash layers studied in old work might be carried out by means of both routine analysis of grain discrete shards for geochemical characterisation and radioisotopic dating. there is the need to enhance knowledge of dispersal of the identified marker tephras, which is still incomplete and non-uniform in space. as for dispersal in very distal areas, a further hint for future research is suggested by the increasing findings of quaternary tephra likely originated in italy within continental successions of middle and eastern europe (jahns & bogaard, 1998; pyle et al., 1998; pouclet et al., 1999; horvath, 2001; pinti et al., 2001; schmidt et al., 2002). together with earlier evidence (melekestzev et al., 1984; harkovska et al., 1990), they strongly suggest that some italian ash layers might have enormous areal distribution. future tephra studies could be addressed towards investigation of distal sequences so far considered free of tephra layers. new analytical techniques are available to this purpose that enable identification and characterisation of tephra horizons that are not detectable by visual inspection (e.g. rose et al., 1996). extension of italian ash layers to regions external to the mediterranean would open the prospect for precise correlation of palaeoenvironmental records across the european continent. reliable reconstruction of ash dispersal might also contribute to infer the atmospheric circulation patterns over the past. finally, the huge explosive character of the quaternary mediterranean volcanoes suggests that the largest eruptions might have produced significant atmospheric perturbation, even on a global scale. actually, a few sulphate peaks in an ice core record collected in greenland are thought to be related to italian eruptions occurred in historical and prehistoric times (zielinski, 1995; zielinski et al., 1994; 1997). matching of these chemical signals with italian events is still to be demonstrated by the occurrence in the ice of the related volcanic glass. when this relationship will be proved unambiguously, then firm correlation will become possible between sedimentary successions of the central mediterranean and climate records from the north polar region. this will represent a substantial advance towards investigating still open palaeoenvironmental issues as for example the relationship between the north atlantic millennial scale climate variability (i.e. dansgaardoeschger cycles and heinrich events; broecker, 1994) and the mediterranean climate and environment. rreeffeerreenncceess bartolini c., de giuli c. & gianelli g. 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(1994) record of volcanism since 7000 b.c. from the gisp2 greenland ice core and implications for the volcano-climate system. science, 226644, 948-952. 9quaternary distal tephra layers ... impaginato atti il quaternario italian journal of quaternary sciences 1155(1), 2002, 111-120 ssooiill ggeeoocchheemmiissttrryy aanndd ppeeddoollooggiiccaall pprroocceesssseess.. tthhee ccaassee ssttuuddyy ooff tthhee qquuaatteerrnnaarryy ssooiillss ooff tthhee mmoonnttaaggnnoollaa sseenneessee ((cceennttrraall iittaallyy)) ee..aa..cc.. ccoossttaannttiinnii11,, mm.. aannggeelloonnee22,, rr.. nnaappoollii11,, 1istituto sperimentale per lo studio e la difesa del suolo, mi.p.a., p.za d’azeglio, 30, 50121 firenze 2enea, tein-chim, c.r. casaccia, c.p. 2400, 00100 roma a.d. abstract the role of soil as an environmental filter is widely acknowledged, although not fully understood in all the processes involved. unfortunately in the monitoring of some environmental parameters indicative of soil quality, such as heavy metals, we can observe a general tendency to simplify the issue. in fact, data refer only to a part of soil, i.e. the uppermost part, or the plow layer, while characteristics and processes which occur in the lower parts of the profile are neglected. on the other hand many soils, like paleosols, which are quite widespread in italy, have a very thick and complex profile, in which a significant elemental concentration can take place as a result of natural, pedological processes. this stresses the importance of in-depth investigation when the object of laboratory analysis is to provide advice for specific land uses. aim of this work was to study the role played by soil forming processes in addressing element behaviour in some soils of the montagnola senese territory. results of this work show an accumulation of many elements with respect to parent material. however this trend was not uniform in all cases, pointing out that their re-distribution in soil horizons can be related to different pedogenetic processes. the accumulation of some elements in soils can be to some extent related to organic matter content, ph and cation exchange capacity, but mainly in the upper horizons, while clay richness seems to play a more important role in determining the element concentration in all soil horizons: correlation coefficients with high level of significance have been found between clay and ti, k and cr, but also fe, zn and pb are correlated with clay content, with the exception of those horizons, which are affected by element redistribution caused by oxidative-reductive processes. several elements show a time dependent concentration process. ti, k, na and mn seem to increase through time from the holocene, to the upper and middle pleistocene; cr, pb and zn, similarly to fe, from holocene up to the lower pleistocene. the accumulation process proceeds along with clay neo-genesis and illuviation, but it can be affected by clay impoverishment, due to ferrolysis, together with the element mobilisation produced by reducing conditions. if clay impoverishment is characteristic of eluvial horizons and bleached streaks of fragipan and glossic horizons, mobilisation of fe, zn and pb is manifested in the reduced parts of almost all the horizons with bad drainage. riassunto l’importanza del suolo come ‘filtro ambientale’ è generalmente riconosciuta, sebbene non ancora pienamente compresa in tutti i processi che ne sono coinvolti. nel monitoraggio di alcuni parametri ambientali indicativi la qualità del suolo, come ad esempio i metalli pesanti, si tende in genere a semplificare le cose, riferendosi solo ad una parte del suolo, quella più superficiale, o strato lavorato, mentre le caratteristiche degli orizzonti sottostanti ed i processi che avvengono nella parte profonda del profilo non sono considerati. d’altra parte molti suoli, in particolare i paleosuoli, piuttosto diffusi in italia, sono caratterizzati da un profilo molto profondo e complesso, nel quale si può verificare un significativo incremento di elementi per cause naturali, legate a processi pedologici. scopo di questo lavoro è quello di studiare il ruolo svolto dai processi pedogenetici nell’indirizzare l’accumulo di elementi nei suoli della montagnola senese. i risultati del lavoro evidenziano il verificarsi di un accumulo di elementi rispetto al materiale parentale; tuttavia questa tendenza non si è realizzata allo stesso modo per tutti i suoli. ciò suggerisce che la ridistribuzione degli elementi negli orizzonti pedologici può essere messa in relazione con differenti processi pedogenetici. l’accumulo di alcuni elementi nei suoli è stato correlato al contenuto in sostanza organica, al ph e alla capacità di scambio cationico, soprattutto nei primi orizzonti, mentre un ruolo maggiore è svolto dall’argilla nel determinare il contenuto in elementi di tutti gli altri orizzonti. coefficienti di correlazione altamente significativi sono stati riscontrati tra argilla e ti, k e cr ma anche con fe, zn e pb. tuttavia questa evidenza non si manifesta negli orizzonti caratterizzati da una ridistribuzione degli elementi provocata da processi di ossidoriduzione. molti elementi evidenziano un processo di accumulo dipendente dal tempo. ti, k, na e mn mostrano di aumentare col tempo passando dall’olocene al pleistocene superiore e medio; cr, pb e zn, analogamente al ferro, dall’olocene fino al pleistocene inferiore. il processo di accumulo procede di regola assieme alla neogenesi ed accumulo di argilla, ma può essere influenzato da altri due processi: l’impoverimento di argilla, attivo negli orizzonti eluviali, glossici e nei fragipan, e la mobilizzazione degli elementi, che avviene in tutti gli orizzonti che presentano condizioni riducenti. key words: trace and heavy metals, soil geochemistry, paleosols, siena, italy parole chiave: metalli pesanti ed in traccia, geochimica dei suoli, paleosuoli, siena, italia. 11.. iinnttrroodduuccttiioonn knowledge of the concentration of trace elements in soil, especially heavy metals, is of utmost environmental relevance when the purpose is to determine the pollutant rate related to anthropogenic influences. in the last decade several western countries have carried out many research programs to establish valid background levels to be used as reference points to discriminate contamination. unfortunately in our country a systematic and organic national program to assess trace element distribution and background values in soil is far from being completed. as a direct consequence we can witness the great difficulties encountered by national and regional legislation to establish valid and useful reference points to assess contamination. however, little is known about the thresholds which can cause damage to the soil-plant ecosystem and the limits can vary widely according to the different countries' approach to this problem (adriano et al., 1995; tab. 1). besides, recent studies have demonstrated the irreversible effects upon the soil microbial ecosystem of soil metal concentrations having values which are well below european and italians limits (brookes, 2001). element content in soils may vary according to agricultural practices, but, to a great extent natural causes also play a role. the influence of parent material, for instance, is well-known (fergusson, 1990; angelone & bini, 1992); nevertheless the contribution of long-lasting natural processes, like those occurring in paleosols, has not been well-established yet. moreover, legislation related to soil quality and pollution generally tends to simplify the issue, in particular it refers to only a part of the soil, that is the uppermost part, or the plow layer, while characteristics and processes of the lower parts of the profile are often neglected. this simplification does not take into account the possibility that the upper part of the soil can be thinned, or even removed by some agricultural practices or because of soil erosion. another simplification concerns soil horizons often considered to be homogeneous, whereas element accumulation in soils, and particularly in paleosols, can occur only in parts of some horizons. this can be of great relevance in interpreting analytical results for practical purposes, not only those related to the environment, but also to the agricultural uses of soils (costantini, 1999), and should steer the soil sampling. in mediterranean countries, and particularly in italy, paleosols are quite widespread and a significant elemental concentration can occur in some parts as a result of paleopedological processes. these processes are usually accompanied by a more or less pronounced soil reddening or the formation of nodules, but exceptions are frequent. in this work, the elemental distribution in some soils of the montagnola senese territory has been studied and put in relation to main soil properties (ph, clay, om, cec), major elements (fe, al), estimated soil age, soil morphology (genetic horizons, redoximorphic features) with the aim of studying the role played by soil forming processes in addressing element behaviour. 22.. mmaatteerriiaallss aanndd mmeetthhooddss 22..11 ssooiill aannaallyyssiiss the soils of the montagnola senese territory have been previously studied by costantini et al. (1996) to explain the genesis of fragipan and other close-packed horizons. more than 50 profiles of the area have been described and analysed. a dozen of them, developed on acid metamorphic rocks and on mainly siliceous colluvial and alluvial deposits, were also studied for their element composition. soil description followed the soil survey staff methodology (1993), routine analysis was in compliance with the italian official methods (siss, 1985). plinthite nodules were submitted to the test of wood and perkins (1976), with immersion of samples for two hours in water, to check the persistence of aggregation. the counting of nodules and pseudomorphic nodules in the sands was made on 26 horizons pertaining to seven selected soils, utilising the optical microscope at different magnifications and considering 300 grains from each sand class; percentage values of nodules were then referred to percentage of fine earth, without taking into account possible differences in specific gravity. geochemical analysis was performed on 67 soil horizons belonging to 12 representative profiles. soil samples were dried beforehand at 40°c, ground and sieved through a 2 mm teflon coated sieve. homogenised sub-samples were ground with an agate ball mill to obtain a fraction < 0.1 mm. approximately 500 mg of homogenised sub-sample were weighed in a teflon bomb. metal extraction was carried out adding a mixture 5 ml of aqua regia (5 ml) and ultra pure hf (2 ml). saturated h3bo3 was successively added to buffer the excess of hf. major and trace element analysis was carried out by perkin elmer 5100 aas at flame (k, na, mn); and with an aas equipped with a zeeman background corrector for cd, cu, cr, pb and zn. icp was used to analyse ca, al, mg, fe and ti. all the analytical procedures were tested beforehand with a data quality control programme using international soils crms, samples duplicate and reagent blanks. 112 total soil metal concentration, mg kg-1 soil european union year ccdd ccuu ccrr ppbb zznn community 1986 1-3 50-140 100-150 50-300 150-300 france 1988 2 100 150 100 300 germany 1992 1.5 60 100 100 200 united kingdom 1989 3 135 400 300 300 italy 1992 1.5 100 (a) 100 300 (a) = bartlett test for soil oxidation capacity <1 table1 maximum concentrations of metals allowed in agricultural soils treated with sewage sludge (after adriano et al., 1995). concentrazioni massime di metalli permesse nei suoli agricoli trattati con fanghi di depurazione (da adriano et al., 1995). e.a.c. costantini, m. angelone & r. napoli 33.. rreessuullttss aanndd ddiissccuussssiioonn 33..11.. ggeenneerraall oouuttlliinneess ooff tthhee aarreeaa the study area is a small ridge located in central tuscany, covering just under 20 km2. it is made up of several hills, with dominant heights ranging from 400 to 500 meters and a maximum of 671 meters a.s.l. the area underwent intense geomorphological evolution during the pliocene and quaternary, with alternating periods of erosion and stability. the rising of the ridge led to the erosion of the slopes, but several surfaces remained stable (e.g. karst depressions) or were stable over a long period (e.g. colluvial areas). four main lithological units could be distinguished: i) acid metamorphic rocks, consisting of chloritic and sericitic fine-grained schist, jasper, quartzose micro and macro conglomerate and violet schist breccias (mesozoic); ii) calcareous rocks, composed of flint limestone, marble, dolomite and cavernous limestone mesozoic in age, but partially reworked by the miocene sea; iii) mainly calcareous or iv) mainly siliceous colluvial and alluvial deposits, the mineralogy of which derives from the mixing of the above mentioned rocks. climatic data for the area were obtained from simignano (si) and siena. at simignano (43°18' lat. n; 419 m a.s.l., 8 km west of siena) the average annual rainfall is 1019 mm, with maximum in october (119.8 mm) and minimum in july (36.4 mm). in siena (43°19' lat. n; 348 m a.s.l.) the average annual temperature is 13.2°c, the warmest month is july (22.1°), the coldest is january (5.8°). the soil moisture regime, evaluated by the newhall computation (newhall, 1972) is "udic" with a water holding capacity of 200, 100 and 50 mm, whereas the soil temperature regime, according to soil taxonomy (soil survey staff, 1999) is "mesic" (8<t<15° c). land use of the area is mainly woodland, with dominance of chestnut trees (castanea sativa) on acid metamorphic rocks and acid soils, and evergreen holm oak (quercus ilex) on shallow soils on limestone. agricultural lands are limited by the stoniness of the soils on limestone and the steepness of morphology; however, almost a third of the area is cultivated with small grain crops and maize, grasslands, vineyards, olive groves and orchards. possible sources of soil contamination are limited to the few farms which practice spreading pig slurries on soils before cereal cultivation. these soils, however have not been included in this study. 33..22 ssooiill ccllaassssiiffiiccaattiioonn aanndd eessttiimmaatteedd aaggee regarding soil age, the only available dating is from the bottom of a studied profile, ascertained to be at least cromerian (lower middle pleistocene, panizza, 1985) by means of paleonthological finds (fondi, 1972). however, on the basis of a geomorphological reconstruction, the micromorphological evidence and chemical characteristics, it was possible to assess the approximate age of the selected soils as dating back to holocene, upper and middle pleistocene, and to lower pleistocene ages (costantini et al. , 1996). micromorphological results, in particular, concur with those found by cremaschi & sevink (1987) in soils belonging to the same pleistocene ages in italy. according to the soil taxonomy (soil survey staff, 1999) the soils were classified as udorthents, dystrudepts, hapludalf, fragiudalf, fraglossudalf, paleudalf and plinthaqualf, or as leptosols, cambisols, luvisols, alisols and plinthosols according to the world reference base for soil resources classification (fao et al, 1998). clay neo-genesis and accumulation within b horizon is a common feature of many of them, as well as iron release from parent material leading to soil reddening. iron and manganese mobilisation and concentration, due to oxidation and reduction processes and expressed as bleached streaks, reddish and black mottles or as nodule elaboration, is another frequent process. other processes, such as fragipan and glossic horizon formation, clay impoverishment inside bleached streaks (i.e. ferrolysis, brinkman, 1970) and soil acidification, are connotative of specific environmental conditions (costantini et al., 1996). 33..33 oovveerraallll ggeeoocchheemmiiccaall cchhaarraacctteerriissttiiccss aanndd ttrreennddss descriptive statistics of major and trace element concentration are reported in table 2, while the rock composition can be seen in table 3. on average, the heavy metal concentration of these soils is similar to or lower than those considered typical for italian not-polluted soils (angelone & bini,1992). amongst the studied elements, aluminium and iron are the most abundant, as expected considering the nature of the parent material (duchaufour, 1977); however, maximum values of cd, cu, cr, pb and zn are more interesting, being close to or higher than the regulation threshold (tab.1). these limits can be exceeded in superficial horizons (cu, cr) as well as within the b horizons (cd, cu, cr, pb, zn) and, only in the case of cu and cr, also in the deepest horizons. the recorded data do not allow us to assume soil pollution (kabata-pendias & pendias, 1992); however they do emphasise the practical interest of knowing the possible causes of high element content of some of these soils. although we can observe a probable accumulation of many elements in soil, with respect to the parent material, this trend has not taken place in the same way for each element. this suggests that element re-distribution within the soil horizons can be related to different pedogenetic processes. actually, some elements tend to slightly increase or remain constant with depth (zn, al, mg, cu, na), some others localise within surface (ca) and b horizons (mn) or concentrate in b horizons (k, cd, ti, cr, pb and fe). a first step towards the understanding of the causes of accumulation was obtained by correlating the element concentration in soil horizons to clay and organic matter, ph and cation exchange capacity. organic matter was found significantly correlated (p<0.01) with cd (r=0.99) and, considering only the superficial a and e horizons, with ca (r=0.52); ph was found to be well correlated with cd (r=0.98) and, only in the upper horizons, with cu (r=0.62); cec was correlated with cd (r=0.87) and, also in this case only for the a and e horizons, with al (r=0.72), mg (r=0.56), k (r=0.72), mn (r=0.54) and zn (r=0.85). these results seem to indicate that, as already observed by others authors (kabata-pendias & pendias,1992, mckeague & wolynetz, 1980), standard chemical parameters, and in particular organic matter, can significantly influence the accumulation of some elements in soils, mainly in the upper horizons. 113soil geochemistry ... 114 a ll so il h o ri zo n s aa ll cc aa mm gg kk nn aa ff ee mm nn tt ii cc dd cc uu cc rr pp bb zz nn oo ..mm .. cc ..ee ..cc .. cc llaa yy pp hh m e a n 2 0 7 3 7 4 5 5 1 9 5 4 1 3 8 8 9 2 8 0 7 2 9 6 7 7 5 3 7 1 5 2 6 0 ,1 3 5 0 ,3 7 9 ,1 2 6 ,4 6 4 ,0 0 ,6 3 1 0 ,2 2 7 ,6 6 ,2 m in im u m 5 0 0 0 2 0 ,0 2 2 ,0 4 6 0 0 7 2 0 5 6 0 0 3 4 ,0 1 7 8 0 ,0 1 1 3 ,0 1 9 ,0 1 ,0 0 1 2 ,0 0 ,0 1 5 ,0 5 ,0 4 ,2 m a xi m u n 6 6 8 0 0 2 5 8 0 5 0 2 0 4 2 2 0 0 1 5 6 0 0 9 3 0 0 0 2 6 3 0 3 7 9 0 1 ,7 0 1 1 4 1 6 8 1 2 0 1 6 0 4 ,2 0 2 0 ,6 6 0 ,0 8 ,3 s ta n d a rd e rr p r 1 2 1 5 4 4 9 7 1 0 1 1 5 6 2 4 2 4 2 5 1 7 4 4 3 5 5 8 7 4 5 0 ,2 8 2 5 ,3 3 6 ,1 2 1 ,3 3 1 ,9 0 ,1 2 0 ,4 1 ,6 0 ,1 n u m b e r o f d a ta 6 7 6 7 6 6 6 7 6 7 6 7 6 7 6 7 5 3 6 7 6 7 6 7 6 6 5 3 5 5 6 7 6 6 o n ly a a n d e h o ri zo n s m e a n 1 9 2 4 7 8 7 2 1 9 3 7 1 1 1 8 4 2 4 0 5 2 4 2 4 3 6 0 5 1 2 2 5 0 ,0 8 4 6 ,5 7 2 ,3 2 0 ,7 5 0 ,1 1 ,5 9 1 0 ,4 1 8 ,7 6 ,1 m in im u m 5 4 0 0 3 6 ,0 6 6 4 4 6 0 0 1 2 1 0 1 0 2 0 0 1 6 3 2 9 3 0 ,0 3 1 3 ,0 2 6 ,0 1 ,0 0 1 2 ,0 0 ,7 0 5 ,0 5 ,0 4 ,5 m a xi m u m 3 9 7 0 0 2 5 8 0 3 4 6 0 1 6 1 0 0 4 6 0 0 4 3 9 0 0 2 0 5 0 2 2 9 0 0 ,1 5 1 1 1 1 6 6 4 6 ,0 1 1 6 4 ,2 0 1 5 ,0 3 7 ,0 7 ,5 s ta n d a rd e rr o r 1 0 1 2 4 7 2 7 8 4 8 3 7 4 0 8 2 3 1 0 2 0 0 4 6 1 7 3 1 0 ,0 4 2 9 ,5 4 2 ,1 1 2 ,4 2 7 ,9 0 ,2 6 1 ,5 2 ,7 0 ,3 n u m b e r o f d a ta 1 5 1 5 1 5 1 5 1 5 1 5 1 5 1 5 1 2 1 5 1 5 1 5 1 5 1 5 6 1 5 1 4 o n ly b h o ri zo n s m e a n 2 1 0 4 5 3 3 7 1 9 1 4 1 5 0 0 4 2 9 3 7 3 2 8 0 9 5 3 6 1 7 1 2 0 ,1 6 4 8 ,8 8 3 ,7 3 0 ,3 6 7 ,9 0 ,2 2 1 0 ,2 3 1 ,9 6 ,3 m in im u m 5 0 0 0 2 0 ,0 2 3 6 7 1 0 0 8 7 0 8 0 0 0 3 4 ,0 1 7 8 0 ,0 1 1 5 ,0 1 9 ,0 4 ,0 1 5 ,0 0 ,0 1 5 ,4 1 0 ,0 4 ,6 m a xi m u m 6 6 8 0 0 1 3 9 0 4 2 4 0 4 2 2 0 0 1 5 6 0 0 9 3 0 0 0 2 6 3 0 3 7 9 0 1 ,7 0 1 1 3 1 6 8 1 2 0 1 6 0 0 ,8 0 2 0 ,6 6 0 ,0 8 ,3 s ta n d a rd e rr o r 1 8 8 6 8 0 ,4 1 4 0 8 5 9 3 8 7 2 7 7 8 8 8 1 0 0 0 ,0 5 3 ,1 4 ,9 3 ,3 7 4 ,5 0 ,0 3 0 ,5 1 ,7 0 ,2 n u m b e r o f d a ta 4 7 4 7 4 7 4 7 4 7 4 7 4 7 4 7 3 8 4 7 4 7 4 7 4 7 3 6 4 6 4 7 4 7 o n ly c h o ri zo n s m e a n 2 2 3 2 0 3 1 4 2 4 9 6 1 1 5 2 4 2 7 8 8 1 6 5 3 0 3 4 6 6 8 6 0 ,0 4 7 5 ,4 5 5 ,8 6 ,4 0 7 0 ,3 0 ,8 0 1 0 ,5 1 4 ,0 4 ,9 m in im u m 1 2 2 0 0 2 2 0 2 2 ,0 6 6 3 0 7 2 0 5 6 0 0 5 5 ,0 3 3 0 0 ,0 2 2 8 ,0 3 3 ,0 1 ,0 0 1 6 ,0 0 ,1 0 5 ,7 1 0 ,0 4 ,2 m a xi m u m 3 8 7 0 0 4 4 6 5 0 2 0 1 8 7 0 0 9 1 7 0 2 2 4 5 0 8 4 7 1 6 7 0 0 ,0 7 1 1 4 1 1 4 1 3 1 3 3 1 ,5 0 1 3 ,1 2 2 ,0 5 ,1 s ta n d a rd e rr o r 5 3 3 8 3 9 ,2 1 0 2 2 2 2 2 2 1 6 0 5 2 9 0 7 1 4 7 2 4 8 0 ,0 1 1 6 ,9 1 4 ,9 2 ,4 0 2 5 ,0 0 ,7 0 2 ,4 2 ,2 0 ,2 n u m b e r o f d a ta 5 5 4 5 5 5 5 5 3 5 5 5 4 2 3 5 5 t yp ic a l v a lu e s fo r it a lia n n o tp o llu te d s o ils ( a fe te r a n g e lo n e a n d b in i, 1 9 9 2 ) 3 7 0 0 0 9 0 0 0 ,5 3 5 1 ,0 1 0 0 2 1 ,0 8 9 ,0 t a b le 2 d e sc ri p tiv e s ta tis tic s o f m a jo r a n d t ra ce e le m e n t co n ce n tr a tio n ( p p m ) co m p a re d t o m a in c h e m ic a l v a lu e s s ta tis tic h e d e sc ri tt iv e d e lla c o n ce n tr a zi o n e d e g li e le m e n ti m a g g io ri e in t ra cc e ( p p m ), c o n fr o n ta ti co n i p ri n ci p a li ca ra tt e ri c h im ic i e.a.c. costantini, m. angelone & r. napoli on the other hand, the clay content seems to be more relevant. correlation coefficients with a high level of significance have been found between clay of each horizon and ti (r=0.65), k (r=0.58), and cr (r=0.55), while the correlation was less evident with zn (0.38), fe (0.31; p<0.05) and pb (0.29; p<0.05). on the other hand, fe (r=0.91), zn (r=0.58) and pb (r=0.57) were found highly correlated with clay in all horizons, excluding those with plinthite and the reduced parts. thus these last three elements show a concentration trend similar to the others, i.e. they follow the time and pedoclimate dependent clay increase, but it is also influenced by the oxidative-reductive processes. aluminium and iron are the dominant elements in the studied soils, so it could well be that other elements were associated with them. in actual fact, the former was found well correlated only with mg (r=0.68), and the latter with cr (r=0.58). if we do not take into account plinthite and reduced horizons, however, aluminium is fairly correlated with mg (r=0.69) and cd (0.57), as well as iron with ti (r=0.47), k (r=0.42), pb (r=0.59) and zn (r=0.41). even in these cases, the prominent role played by the element mobilisation, due to the change in their chemical state, is highlighted. finally, aluminium was found correlated with ca (r=0.52), but only in the superficial horizons. 33..44 eelleemmeenntt ccoonncceennttrraattiioonn aanndd ssooiill aaggee in a previous work, it was demonstrated that the ageing of the studied soils is characterised by a progressive increase in the clay content, a slight reduction of the cec of clay and a marked increase in total and free iron content, which is particularly impressive in the oldest soils (costantini et al., 1996). in this work we have grouped the studied soils according to their estimated age – holocene, upper and middle pleistocene, lower pleistocene and statistically tested them to underline possible significantly differing element concentrations. although the relationships between element supplying and age have to be considered only as indicative, because of the several other factors affecting the element concentration viz. lithological and chronological discontinuities between horizons of the same soil, or differences between parts of the same horizon some possible indications about the elements which are more time dependent can be pointed out (table 4). among the studied soil components, al, cd, cu and mg do not show any significant trend related to soil age. on the other hand, cr, pb and zn show an accumulation process similar to that of iron, i.e. a progressive increase with age, which is particularly evident for cr (fig. 1); ti and k are significantly lower in holocene soils, rather than in older soil horizons, whereas na and mn have higher mean values in soils and horizons attributed to 115 al ca mg fe ti k na mn cd cu cr pb zn quartzose 9000 176 320 6900 430 5830 1030 50 0,06 4 192 155 61 micro conglomerate sericitic fine61200 296 4300 39200 3540 24000 3815 2190 0,06 87 107 325 138 grained schist violet schist 58000 320 600 26000 1980 28100 4190 51 0,05 12 136 210 73 chloritic schist 3000 360 220 7000 180 4600 2250 6 0,21 8 6 32 24 jasper 11700 140 1320 9400 5500 740 258 0,04 48 10 28 mean 28580 258 1352 17700 1533 13606 2405 511 0,08 32 90 181 65 table 3 element concentration in some samples of the main parent material lithotypes of the studied soils (ppm). concentrazione degli elementi in alcuni campioni dei litotipi principali del materiale parentale dei suoli studiati (ppm). ccaa ffee ttii kk nnaa mmnn ccrr ppbb zznn oo..mm.. cc..ee..cc.. ccllaayy pphh holocene soil horizons mean 745 18039 757 8886 1896 664 46.1 12.3 41.9 1.23 8.06 12.6 5.26 number of data 18 18 18 18 18 18 18 18 17 16 11 18 17 upper and middle pleistocene soil horizons mean 351 26402 1870 17115 4398 802 73.4 21.6 67.6 0.31 11.2 28.9 5.78 number of data 20 20 20 20 20 20 20 20 20 11 18 20 20 lower pleistocene soil horizons mean 347 39159 1767 14771 2276 276 103 38.4 74.4 0.39 10.4 35.9 6.95 number of data 29 29 29 29 29 29 29 29 29 26 26 29 29 table 4 element concentration in soil horizons of different estimated age (ppm) compared to main chemical values; elements, ph and clay are significantly different for soil age with the kruskal-wallis test with p<0.001, c.e.c. and o.m. with p<0.05. concentrazione degli elementi negli orizzonti pedologici di differenti età stimate (ppm) confrontati con i principali caratteri chimici; gli elementi, il ph e l’argilla sono differenti significativamente per età del suolo con il test di kruskal-wallis con p<0.001, c.e.c. e o.m. con p<0.05. soil geochemistry ... the upper and middle pleistocene. finally there is a clear decrease in ca with soil ageing, possibly due to the leaching process and the scanty supply from the parent material. 33..55 eelleemmeenntt aaccccuummuullaattiioonn ppaatthhwwaayyss aanndd ssooiill mmoorrpphhoo-llooggyy three profiles have been selected to exemplify how the accumulation process becomes evident in soils. they illustrate different profile morphology and element accumulation pathways, as a consequence of the pedogenetic processes which have occurred. profile 9 fragic paleudalf (soil taxonomy 1999); chromi-profondic luvisol (bathifragic) (wrb 1998). holocene in age in its upper part (a, e and bt horizons), pleistocene in age in the deepest horizons, it is characterised by evident weathering, leading to the release of elements, in particular iron, which gives the soil its reddish-brown colour, as well as clay neo-formation and illuviation into depth. moreover, a close-packed horizon has been formed (fragipan) which limits water and root penetration and causes the formation of bleached tongues (figures 2 and 3; a, e, bt, 2btx1, 4bc, r, etc.: designations for soil horizons1). in this profile, iron distribution is similar to that of clay; inside the bleached streaks, where root penetration is active, ferrolysis determines clay and iron depletion, but does not affect ti and k (photo 1). profile 47 aquic fraglossudalf (soil taxonomy 1999); glossalbi-stagnic luvisol (profondic, chromic, fragic) (wrb 1998). lower pleistocene in age, it is older and redder than the previous soil; pedological processes are similar to those of profile 9, but more pronounced (photo 2). in particular, depletion in the reduced zones affected not only clay and iron, but also potassium and titanium (figures 4 and 5). in the same geomorphological unit, but in a lower position, soils like profile 48 plinthaquic paleudalf (soil taxonomy 1999); eutri-endostagnic plinthosol (wrb 1998) are widespread (photo 3). they have neither fragipan nor clay impoverishment inside the bleached streaks. the groundwater has been fluctuating inside this iron-rich soil for so long that iron movement and aggregation in form of concretions and nodules of plinthite has been produced (photo 4). the presence of water has provoked iron reduction and removal from the streaks, but clay has not been removed, rather it tends to concentrate inside the bleached zones. as a result, the oxidised zones of the profile became coarser in particle size and a residual concentration of clay and titanium in the bleached mottles took place (figures 6 and 7). the process of iron concentration, from dispersed in the groundmass to aggregated in nodules, can be better appreciated by optical stereo-microscope. the 116 f ig . 1 c r co n te n t o f st u d ie d p ro fil e s a cc o rd in g t o t h e ir e st im a te d a g e ( p p m ) c o n te n u to in c r d e i p ro fil i s tu d ia ti in r e la zi o n e a lla lo ro e tà s tim a ta ( p p m ) 1 a = surface horizon with organic matter accumulation, ap = ploughed horizon, e = eluvial horizon, bt = horizon with clay accumulation, btx = fragipan, btg = bad drained horizon with clay accumulation, btgv = as before with plinthite, bc = weathered and partially structured bedrock, r = hard bedrock. number preceding letters indicates lithological and/or chronological discontinuity; those following letters indicate sub horizon; red or -o: reduced, bleached streaks or tongues; ox or -o: oxidized masses. e.a.c. costantini, m. angelone & r. napoli frequency of nodules and pseudomorphic nodules in four sand fractions of two horizons from seven of the examined soils are reported in figure 8. nodules in the sand fractions were present in all the studied profiles, but reached striking percentages in the profile 48 (up to more than 30% of the fine earth), especially in the finer 117 photo 1 particular of the bleached streaks inside the fragipan of profile 9, where ferrolysis takes place. particolare delle striature biancastre all’interno del fragipan del profilo 9, dove vi è ferrolisi. sand fractions. in most cases, the colour of the nodules fell to hue 2.5 yr (munsell soil colour charts), but could reach 10 r in the most rubified soils (profiles 25 and 47) and 10 yr in the yellowish ones (profiles 46 and 48). as a general rule, the finer the sand fractions, the redder the nodules. this could be related to the presence of a fig. 2 fe and k distribution within profile 9 distribuzione del fe e del k all’interno del profilo 9 fig. 3 ti and clay distribution within profile 9 distribuzione del ti e dell’argilla all’interno del profilo 9 fig. 4 fe and k distribution within profile 47 distribuzione del fe e del k all’interno del profilo 47 fig. 5 ti and clay distribution within profile 47 distribuzione del ti e dell’argilla all’interno del profilo 47. soil geochemistry ... progressive long-lasting process, which induces transformation of iron from hematite into goethite, as already observed by other authors in some oxisols of central brazil and in laterite (jeanroy et al., 1991; curi & franzmeyer, 1984, 1987; da motta & kämpf, 1992; macedo & bryant, 1987; nahon, 1991). 118 photo 3 profile 48. the groundwater has been fluctuating inside this iron-rich soil so long as to produce an huge iron aggregation in the form of concretions and nodules of plinthite. profilo 48. la falda freatica ha fluttuato così a lungo in questo suolo ricco di ferro da produrre un enorme accumulo di ferro sotto forma di concrezioni e noduli di plintite. photo 2 the soil profile 47 is older and redder than the former profile 9; depletion in the reduced zones affected not only clay and iron, but also potassium and titanium. il suolo del profilo 47 è più antico e più rosso del precedente profilo 9, l’impoverimento nelle zone ridotte interessa non solamente l’argilla e il ferro, ma anche il potassio e il titanio. fig. 6 fe and k distribution within profile 48 distribuzione del fe e del k all’interno del profilo 48 fig. 7 ti and clay distribution within profile 48 distribuzione del ti e dell’argilla all’interno del profilo 48 44.. ccoonncclluussiioonnss element distribution along soil profiles well reflects the long-lasting influence of weathering and of soil forming processes that have been operating on the area. the accumulation of some elements in soils can to a certain extent be put in relation to organic matter content, ph and cation exchange capacity, but mainly in the upper horizons. on the other hand, clay richness seems to play a more important role in determining the element e.a.c. costantini, m. angelone & r. napoli 119 photo 4 particular of the horizon with plinthite nodules. the anaerobic conditions have provoked iron reduction and removal from the streaks, but clay has not been removed, rather it tends to concentrate inside the bleached zones, and along with it titanium. the yellowish mass is very rich of nodules and concretions. particolare dell’orizzonte con noduli di plintite. le condizioni anaerobiche hanno provocato la riduzione del ferro e la sua rimozione dalle striature, ma l’argilla non è stata rimossa, piuttosto tende a concentrarsi all’interno delle zone biancastre, e con lei il titanio. la massa giallastra è molto ricca di noduli e concrezioni e, al suo interno, gli ossidi di ferro sembrano essersi trasformati da ematite a goethite. fig. 8 nodules and pseudomorphic nodules in the sand fractions of selected soils (%) noduli e noduli pseudomorfi nelle frazioni sabbiose di suoli selezionati (%) soil geochemistry ... concentration in all soil horizons. correlation coefficients with high level of significance have been found between clay and ti, k and cr. also fe, zn and pb are related to clay content, especially if the horizons which are affected by element redistribution caused by oxidative-reductive processes are excluded. several elements show a time dependent concentration process. ti, k, na and mn seem to increase with time from the holocene, to the upper and middle pleistocene; cr, pb and zn, similarly to fe, from holocene up to the lower pleistocene. the accumulation process proceeds along with clay neo-genesis and illuviation, but it can be affected by clay impoverishment, due to ferrolysis, besides element mobilisation, produced by reducing conditions. if clay impoverishment is characteristic of eluvial horizons and bleached streaks of fragipan and glossic horizons, mobilisation of fe, zn and pb is manifested in the reduced parts of almost all the horizons with bad drainage. all in all, the soils of the montagnola senese highlight that in the study of soil geochemistry there is a need for careful investigation of what is often a complex reality. soils, and particularly paleosols, where a significant element accumulation can take place as a result of natural pedological processes, have to be considered not only in terms of their superficial aspects (the plow layer), but also in the characteristics of the entire profile. for this reason, a thorough soil field survey is essential in evaluating the capacity of the site to accept pollutants, in order to guarantee the maintenance of soil filter and sink capacity, and should be provided for by regulations. aacckknnoowwlleeddggeemmeennttss the soil survey and routine analysis were carried out by napoli and costantini, the geochemical analysis by angelone. the text was elaborated and prepared by costantini on the basis of a common discussion. authors thanks prof. claudio bini of the university of venice (italy) for his helpful criticisms on style and content of the manuscript. rreeffeerreenncceess adriano d.c., chlopecka a., kaplan d. i., clijsters h., & vangrosveld j., 1995 soil contamination and remediation: philosophy, science and technology. proceeding of the third icobte – int. con. on the biogeochemistry of the trace elements. paris, cdrom. angelone m. & bini c., 1992 trace elements concentrations in soils and plants of western europe. in: biogechemistry of trace metals, ed. by domy c. adriano. lewis pub. 19-60. brinkman r., 1970 ferrolysis, a hydromorphic soil forming process. geoderma, 33, 199-206. brookes, p. c. 2001 changes in soil microbial properties as indicators of adverse effects of heavy metals. mem. sc. fis. e nat., 118, xxxxiivv, pp.205-227. costantini e.a.c., 1999 soil survey and chemical parameters evaluation in viticultural zoning. atti del 2° convegno internazionale “zonazione viticola”. siena, maggio 1998, 127-137. costantini e.a.c., napoli r., & bragato g., 1996 properties and geographic relevance of fragipan and other close-packed horizons in a non-glaciated mediterranean region. geografia fisica e dinamica quaternaria, 1199, (11), 29-45. cremaschi m. & sevink j., 1987 micromorphology of paleosols chronosequences on gravelly sediments in northern and central italy . in: soil micromorphology. proceeding of the viith int. working meet. of soil micr., association franc. pour l'etude du sol, paris, 577-582. curi n. & franzmeier d.p., 1984 toposequence of oxisols from the central plateaux of brazil. soil sci.soc. am.j., 4488, 341-346. curi n. & franzmeier d.p., 1987 effect of parent rocks on chemical and mineralogical properties of so-me oxisols in brazil. soil sci.soc. am.j., 5511, 153-158. da motta p.e.f. & kämpf n., 1992 iron oxide properties as support to soil morphological features for prediction of moisture regimes in oxisols of central brazil. in: z.pflanzernähr, bodenk, 115555, 385-390. duchaufour p., 1977 pedologie 1, pédogenèse et classification. masson, paris. fao, isric & isss, 1998 world reference base for soil resources. world soil resources report, 84, fao, roma, pp. 90. fergusson j.e., 1990 the heavy elements: chemistry, environmental impact and healt effects. pergamon press, pp. 614. fondi r., 1972 fauna cromeriana della montagnola senese. paleontographia italica, llxxvvllllll, 1-27. jeanroy e., rajot j.l., pillon p. & herbillon a.j., 1991 differential dissolution of hematite and goethite in dithionite and its implication on soil yellowing. geoderma, 5500, 79-94. kabata pendias a. & pendias h., 1992 trace elements in soils and plants. crc press. macedo j. & bryant r.b., 1987 morphology, mineralogy and genesis of a hydrosequence of oxisols in brazil. soil sci.soc. am.j., 5511, 690-698. mckeague, j.a. & wolynetz, m. s., 1980 backgroun levels of minor and trace elements in some canadian soils. geoderma, 2244, 199-206. nahon d.b., 1991 self-organization in chemical lateritic weathering. geoderma, 5511, 5-13. newhall f., 1972 calcualtion of soil moisture regimes from the climatic record. rev. 4 nimeo-graphed, soil conservation service, usda pp. 17. panizza m., 1985 schemi cronologici del quaternario. geogr. fis. dinam. quat., 88, 44-48. siss (società italiana della scienza del suolo), 1985 metodi normalizzati di analisi del suolo. edagricole, bologna. soil survey staff, 1993 soil survey manual. united states departement of agriculture, hand-book n°18, washington d.c., u.s.a., pp. 437. soil survey staff, 1999 soil taxonomy. usda agricultural handbook 436, washington d.c., u.s.a., pp. 869. wood b.w. & perkins h.f., 1976 a field method for verifying plinthite in southern coastal plain soils. soil sci. 112222, 240-241. 120 ms. ricevuto marzo 2002 ms. received: march 2002 e.a.c. costantini, m. angelone & r. napoli imp. sulpizio aa rreevviieeww ooff tteepphhrroossttrraattiiggrraapphhyy iinn cceennttrraall aanndd ssoouutthheerrnn iittaallyy dduurriinngg tthhee llaasstt 6655 kkaa rroobbeerrttoo ssuullppiizziioo11,,22,, ggiioovvaannnnii zzaanncchheettttaa22,, mmaarrttiinnee ppaatteerrnnee33 && ggiiuusseeppppee ssiiaannii44 1 dipartimento geomineralogico, via orabona 4, 70125, bari, italy 2 dipartimento di scienze della terra, via s. maria 53, 56126, pisa, italy 3 lab. des sciences du climat et de l’environm., cnrs-cea, 91198 gif sur yvette, france 4 fre 2566 orsayterre université paris xi 91405 orsay cedex abstract this work presents an attempt at correlating tephra layers through different proxies in central and southern italy over the last 65 ka. on the basis of the recent refinement of stratigraphy of some italian volcanoes (mainly somma-vesuvius and phlegrean fields) and new lacustrine and marine cores (from lago grande di monticchio and south adriatic sea) 35 dated tephra layers among terrestrial, lacustrine and marine settings are correlated. these correlations supply a detailed and comprehensive chronostratigraphic scheme previously not available. in particular, 9 tephra layers were related to the somma-vesuvius, 16 to the phlegrean fields, 3 to ischia, and 1 to procida, etna, lipari, salina, pantelleria and palinuro seamount explosive activity. one tephra layer has an uncertain source between ischia island and phlegrean fields. finally, dispersal maps of selected tephra layers are shown. riassunto questo lavoro presenta un tentativo di correlazione di livelli di tephra di età minore di 65 ka rinvenuti in depositi marini e lacustri con i corrispondenti livelli piroclastici prossimali. l'area interessata dall'indagine comprende carote marine dai mari tirreno, adriatico, ionio e dal bacino di bannock, mentre i dati dei tephra lacustri provengono da carote ottenute nei laghi di monticchio, vico, mezzano, nemi, valle di castiglione e da depositi di versante della conca del fucino. una carota proviene inoltre dalla laguna di mljet in croazia. le correlazioni di dettaglio dei tephra marini e lacustri con i depositi prossimali sono state possibili grazie al recente raffinamento dei dati riguardanti la cronostratigrafia di alcuni vulcani italiani (in particolare somma-vesuvio e campi flegrei) e ai dati provenienti da nuove carote perforate nel mare adriatico e nel lago grande di monticchio. dei 35 livelli di tephra correlati 9 appartengono ad eruzioni del somma-vesuvio, 16 ai campi flegrei, 3 ad ischia e 1 a procida, etna, lipari, salina, pantelleria e palinuro seamount rispettivamente. un solo livello di tephra risulta difficilmente discriminabile tra una origine flegrea o ischitana. infine le mappe di dispersione di alcuni di questi livelli di tephra sono state tracciate sulla base dei dati prossimali e delle carote marine e lacustri distali. keywords: tephra layers, marine, lacustrine, proximal deposits, italian volcanoes, central mediterranean sea. parole chiave: livelli di tephra, tephra marini, tephra lacustri, vulcani italiani, mediterraneo centrale. il quaternario italian journal of quaternary sciences 1166(1), 2003, 91-108 iinnttrroodduuccttiioonn over the last 50 years, tephra layers have been extensively investigated, since their widespread presence in marine and lacustrine sediments are an invaluable tool used to support geochronological and climatological studies (kennett, 1982; mangerud et al., 1984; bard et al., 1994; paterne et al., 1990; siani et al., 2001; tonthat et al., 2001, among many others). indeed, tephrochronological studies provide precise chronostratigraphic constraints for proxy records and their correlation. moreover, they improve our knowledge of both the areas affected by pyroclastic deposition and the mass of erupted magmas in the past (sparks & huang, 1980). these data are of primary importance in volcanic hazard mitigation, as they are hardly obtained only from terrestrial data. this is especially true for the distal products of ancient eruptions. in the mediterranean sea, a lot of research has dealt with the study of marine cores from tyrrhenian, adriatic, aegean or levantine seas. one of the earliest drilling expeditions in the area was carried out in 194748 (norin, 1958), but the first comprehensive study of tephra layers is that of keller et al. (1978). further on, a refinement of the data was provided by paterne et al. (1986; 1988), mccoy & cornell (1990), fontugne et al. (1989), vezzoli (1991), calanchi et al. (1994), siani et al. (2003) for the tyrrhenian, adriatic and south ionian (bannock basin) seas. in particular, paterne et al. (1986; 1988) and paterne & guichard (1993) provided a detailed chronological and geochemical record of tephra layers over the last 80,000 years. on the other hand tephra layers in lacustrine settings were investigated in detail in recent years, mostly inside the eu funded projects paliclas and euromaars (i.e. narcisi, 1996; calanchi et al., 1996a; 92 r. sulpizio et al. calanchi et al., 1996b; watts et al., 1996; narcisi, 1999a; ramrath et al., 1999). several sedimentary successions of some lakes from central and southern italy were drilled and investigated by interdisciplinary research. in particular, seven lakes (fig. 1) have been considered in this work (lakes of mezzano, vico, albano, nemi, valle di castiglione, monticchio and fucino basin), owing to the presence in their sediments of tephra layers of interest in the investigated time span (<65 ka). this large set of data on marine and lacustrine tephra can be profitably matched with the new stratigraphic, geochemical and chronological data obtained in recent years for some important quaternary volcanoes of southern italy, such as somma-vesuvius (andronico et al., 1995; 1996; cioni et al., 2003a), phlegrean fields (orsi et al., 1996a; di vito et al., 1999; pappalardo et al., 1999; sulpizio et al., 2003), mt etna (coltelli et al., 2000). this paper deals with a review of tephrochronologic correlations among terrestrial (intended as deposits recognised on land, mostly in proximal sites), lacustrine and marine proxies of central-southern italy, with the aim of proposing a comprehensive chronostratigraphic scheme of the tephra succession and dispersion for the last 65 ka. in particular, thephrochronologic correlations are better detailed for the last 18 ka, owing to the availability of a major amount of data on both marine-lacustrine and terrestrial environments (andronico et al., 1995; narcisi, 1996; di vito et al., 1999; siani et al., 2001; wulf et al., 2001; siani et al., 2003 ). however, the correlation in 18-65 ka time span are mainly based on the work of sulpizio et al. (2003), which correlate several poorly-known terrestrial deposits to marine tephra of adriatic and tyrrhenian seas. tthhee tteerrrreessttrriiaall rreeccoorrdd in the investigated time span (<65 ka) the explosive activity of the italian volcanoes was mainly concentrated in the neapolitan area (rosi & sbrana, 1987; santacroce, 1987; poli et al., 1987; vezzoli, 1988; andronico et al., 1995; orsi et al., 1996a; di vito et al., 1999; sulpizio et al., 2003), while few large explosive eruptions occurred at mount etna (kieffer, 1979; coltelli et al., 2000) and eolian islands (keller, 1980; pichler, 1980; frazzetta et al., 1983; crisci et al., 1991; calanchi et al., 1993; de astis et al., 1997; gioncada et al., 2003). during this time span, the roman province, mount vulture and roccamonfina volcanoes were not active, while pantelleria was characterised by a very weak activity out the green tuff eruption (45 ka; gillot, 1984; civetta et al., 1984; mahood & hildreth, 1986; orsi et al., 1991). the stratigraphic record of neapolitan volcanoes has been improved in recent years, especially for the late pleistocene-holocene. in particular, detailed sets of both stratigraphic, chronologic and geochemical data are available for somma-vesuvius (santacroce, 1987; andronico et al., 1995; cioni et al., 2003a) and phlegrean fields (rosi & sbrana, 1987; di vito et al., 1999; orsi et al., 1996a; pappalardo et al., 1999; sulpizio et al., 2003). minor detail exists for the data from ischia and procida volcanoes (vezzoli, 1988; di girolamo & stanzione, 1973; poli et al., 1987; crisci et al., 1989; orsi et al., 1996b). all these data allow the reconstruction of a general chronostratigraphic scheme of the activity of these volcanoes (fig. 2). in the same figure the major explosive eruptions of eolian islands, palinuro seamount and etna volcano are also reported (crisci et al., 1991; calanchi et al., 1993; de astis et al., 1997; coltelli et al., 2000). from this chronostratigraphic scheme, the explosive activity of somma-vesuvius and phlegrean fields emerges characterising the last 18 ka, whereas phlegrean explosive activity dominates the 1865 ka time span, with only few explosive events of pantelleria, ischia and procida islands. tables 1 and 2 summarises the chronology and the main lithological and chemical characteristics of the proximal pyroclastic deposits used in this work for the correlation with marine and lacustrine tephra layers. figure 1 location map of the lacustrine and marine cores considered for this study. lmz – lago di mezzano (ramrath et al., 1999; narcisi, 1999b); vico – lago di vico (narcisi, 1999b); palb1e – lago di albano, lago di nemi and valle di castiglione (calanchi et al., 1996a; narcisi, 1999a); fuc – conca del fucino (slope deposits on the border of the basin; narcisi, 1993); mon – lago grande di monticchio (narcisi et al., 1996; wulf , 2000; wulf et al., 2001); mlj – mljet lagoon (jahns & van den bogaard, 1998); pal948, pal9466, cm9241, cm9242, rf9230 – central adriatic sea cores (calanchi et al., 1998); ket8216, ket8218, md90-917 – south adriatic sea cores (paterne et al., 1988; fontugne et al., 1989; siani et al., 2001; 2003); ket8003, 8004, 8011, 8019, 8022, odp leg 107 – tyrrhenian sea cores (paterne et al., 1988; kallel et al., 1997; calanchi et al., 1994); v10-69, rc9191 – ionian sea cores (keller et al., 1978); ban – bannock basin cores (vezzoli, 1991). 93a review of tephrostratigraphy ... figure 2 detailed chronostratigraphic scheme of somma-vesuvius and phlegrean fields volcanoes of the last 65 ka. in the sommavesuvius chronostratigraphy are shown in italic two eruptions attributed to phlegrean fields (andronico, 1997; zanchetta et al., 2000). schemes of the main explosive eruptions of etna, eolian islands, ischia and procida islands are also shown. the explosive eruption of palinuro seamount is enclosed in the eolian islands chronostratigraphy. note the change in scale for ages older than 19 ka and for eolian islands column. in brackets are shown the published 14c or 39ar/40ar ages. a deino et al. (1994); b ton-that et al. (2001); c pescatore and rolandi (1981); d de rita et al. (1991). 94 tthhee llaaccuussttrriinnee rreeccoorrdd in recent years seven lakes in central and southern italy (lakes mezzano, vico, albano, nemi, valle di castiglione, fucino and monticchio; fig. 1) were drilled, mainly with the aim of studying environmental and climatic conditions in central-southern italy in the past. tephra layers recognised in these lacustrine environments have been investigated in detail by calanchi et al. (1996a, b), ramrath et al. (1999), narcisi (1996; 1999a, b), wulf (2000) and wulf et al. (2001). the lago grande di monticchio (mt vulture; fig. 1) shows the most abundant and representative record of tephra layers, due to its location downwind of the neapolitan volcanoes (fig. 1). narcisi (1996) provided the correlation of 13 tephra layers from the lago grande di monticchio succession to the activity of neapolitan volcanoes, while wulf (2000) and wulf et al. (2001) reported the same layers and several others not recognised by narcisi (1996; fig. 3). indeed, wulf et al. (2001) reported the occurrence of many tephra layers of unknown origin, but, unfortunately, they did not provided chemical analyses, thus preventing their correlations to terrestrial or marine correspondents. for this reason only the well-known and widespread tephra layers y3 and y1, together with the trachytic tephra of agnano m. spina, the latitic tephra of solchiaro and the leucititictephrite-phonolite tephra of pollena (ad 472) have been added to the lago grande di monticchio succession reported by narcisi (1996). the tephra layers recognised in the lago grande di monticchio cores pertain to the major explosive eruptions of somma-vesuvius and phlegrean fields, which occurred in the last 18 ka, whereas the origin of tephra layers in the 18-65 ka time span is less clear, even if the predominance of phlegrean fields and ischia island sources can be inferred by geochemical data (narcisi, 1996; sulpizio et al., 2003; fig. 3). figure 3 shows some differences in respect to the previous correlations of tephra layers from lago grande di monticchio made by narcisi (1996). in particular, layer l3, previously attributed to the interplinian activity between avellino and ad 79 eruptions of sommavesuvius (narcisi, 1996), has been correlated to the avellino eruption of somma-vesuvius. this different correlation has been suggested by eds chemical analyses (especially by the high content of al2o3; cioni et al., 2000) and dispersal of fall deposits of aps and avellino r. sulpizio et al. table 1 chronology and main lithological characteristics of the proximal terrestrial deposits of the last 18.3 ka correlated to the marine and lacustrine tephra layers. a14c age from andronico et al. (1995); b14c age from siani et al. (2001; 2003); c14c age from di vito et al. (1999); d14c age from calanchi et al. (1993). e-lacustrine layer from wulf et al. (2001), marine layer from fontugne et al. (1989); fkeller et al. (1978); g-narcisi et al. (1996), attribution to avellino eruption: this work; h-siani et al. (2003); i-calanchi et al. (1998); lpaterne et al. (1988), paterne & guichard (1993), paterne (1985).characteristics of proximal deposits and lithology of juvenile fragments of pollena, pompeii, avellino, mercato, greenish, pomici di base from santacroce (1987); ap1-2 from andronico & cioni (2002); astroni, agnano p.p. and neapolitan yellow tuff from rosi & sbrana (1987); agnano m. spina from de vita et al. (1999); gabellottofiumebianco from crisci et al. (1991); gm1 from zanchetta et al. (2000); upper pollara from calanchi et al. (1993); lagno amendolare from andronico (1997); biancavilla ignimbrite from de rita et al. (1991). eerruuppttiioonn aaggee cchhaarraacctteerriissttiiccss ooff pprrooxxiimmaall lliitthhoollooggyy ooff jjuuvveenniillee ffrraaggmmeennttss iinnffeerrrreedd tteepphhrraa ddeeppoossiittss ssoouurrccee llaayyeerr pyroclastic fall deposit comprises greenish-grey pumice: highly a thin basal layer of greenish-grey vesicular, porphyritic (lc+pyr+san). pumice followed by several layers tephri-phonolitic chemical sommappoolllleennaa ad 472 of dark grey scoria. accidental composition. dark grey scoria: highly vesuvius pollenae lithics are mainly carbonate and to incipiently vesicular, porphyritic lava fragments. pyroclastic (lc+pyr+san). leucititic-tephriteflows abundant in proximal areas. phonolite chemical composition. pyroclastic fall deposit comprises white-pinkish pumice: highly a basal layer of white-pinkish vesicular, moderately porphyritic pumice followed by an upper (san). phonolitic chemical sommappoommppeeiiii ad 79 layer of grey pumice. accidental composition. grey pumice: highly to vesuvius z1f lithics are mainly carbonate and moderately vesicular, moderately lava fragments. pyroclastic flows porphyritic (san+pyr). tephriabundant in proximal areas. phonolitic chemical composition. pyroclastic fall deposits comprise white pumice: highly vesicular, a thin basal layer of white pumice almost aphiric. phonolitic chemical sommaaapp11--22 3,220±65a followed by an alternation of grey composition. grey scoria: highly to vesuvius l1-2g scoria and ash beds. pyroclastic moderately vesicular, moderately flow deposits are very scarce. porphyritic (san+pyr). pyroclastic fall deposit comprises a white pumice: highly vesicular, basal layer of white pumice followed porphyritic (san). phonolitic chemical by an upper layer of grey pumice. composition. grey pumice: highly to aavveelllliinnoo 3,760±70a accidental lithics are mainly moderately vesicular, porphyritic sommal3g carbonate and lava fragments with (san+pyr). tephri-phonolitic chemical vesuvius subordinate syenites, cumulates and composition. skarns. pyroclastic flows abundant in proximal areas. 95a review of tephrostratigraphy ... eerruuppttiioonn aaggee cchhaarraacctteerriissttiiccss ooff pprrooxxiimmaall lliitthhoollooggyy ooff jjuuvveenniillee ffrraaggmmeennttss iinnffeerrrreedd tteepphhrraa ddeeppoossiittss ssoouurrccee llaayyeerr massive deposit formed by light grey highly vesicular, porphyritic aassttrroonnii 33 3,820±50b pumice. sparse accidental lithics, (san+plag+pyr+bt), light grey in phlegrean 140-17h mainly lava fragments. pyroclastic colour. trachytic to alkali-trachytic in fields flows abundant in proximal areas. composition. pyroclastic fall deposit comprises highly vesicular, porphyritic several poorly sorted pumice layers (san+plag+pyr+bt+lc). pumice aaggnnaannoo 4,130±50c separated by thin, fine ash beds. fragments show a yellowish patina. phlegrean amsi mm.. ssppiinnaa accidental lithics are hydrotermally inner colour: grey; outer colour: fields altered lava fragments. pyroclastic yellowish-brown. trachytic to alkaliflows abundant in proximal areas. trachytic chemical composition. ggaabbeelllloottttoo-several pumice and ash layers highly vesicular, almost aphiric. lipari 7,770±35b interbedded by massive and colour: white. rhyolitic chemical (eolian) e1l ffiiuummeebbiiaannccoo cross-stratified ashes composition islands) pyroclastic fall deposit comprises highly vesicular , almost aphyric. three main layers of white brown colour: white. phonolitic chemical pumice separated by thin, pinkishcomposition. sommammeerrccaattoo 8,010±35a brown ash beds. accidental lithics v-1l are mainly lava fragments and vesuvius subordinate carbonates. pyroclastic flows abundant in proximal areas. ppaalliinnuurroo co-ignimbrite deposits of brown, variably vesicular glass shards of palinuro 9,990±90b fine ash. trachytic composition 275-17 h sseeaammoouunntt accidental lithics are absent. seamount pyroclastic fall deposit comprises highly vesicular , porphyritic three main layers of light brown (san+plag+pyr+bt). pumice fragments aaggnnaannoo 10,480±90b pumice separated by thin, fine ash show a pinkish-brown patina. inner phlegrean c1l pp.. pp.. beds. accidental lithics are lava colour: grey; outer colour: pinkishfields fragments. pyroclastic flows brown. trachytic chemical abundant in proximal areas. composition. several pumice and ash layers juvenile fragments are highly nneeaappoolliittaann 12,100±170b interbedded by massive and vesicular, light grey in colour, almost phlegrean c2s.l. l yyeellllooww ttuuffff cross-stratified ashes aphiric (san+pl+pyr+bt) and alkalifields /395-17h trachytic to latitic in composition. pyroclastic fall deposit comprises an highly vesicular, aphiric, light grey in alternation of three layers of vesicular colour. trachytic chemical phlegrean ggmm11 12,600±110b ash and light coloured pumice. composition. 405-17 h a thick co-ignimbrite ash layer forms fields the upper part of the deposits. uuppppeerr alternation of pyroclastic fall highly vesicular, porphyritic salina 12,750±140d and flow deposits that comprise (bt+pyr+hbl+ol+pl), white in colour. (eolian e2l ppoollllaarraa white pumice. dacitic chemical composition. islands) pyroclastic fall deposit comprises a highly vesicular, aphiric. colour light basal layer of white pumice followed to dark grey. both types are trachytic llaaggnnoo 13,070±90b by fine brown ashes. upper layer in composition. phlegrean 435-17h aammeennddoollaarree comprises mixed white and black fields pumice. sparse accidental lithics, mainly lava fragments. bbiiaannccaavviillllaa at least four ignimbritic flow units highly to moderately vesicular. mount 14,230±85b of ash and juvenile scoriae. colour varies from light to dark grey. y1 f/et1l iiggnniimmbbrriittee benmoreitic composition. etna pyroclastic fall deposit comprises highly to moderately vesicular, almost an alternation of fine to coarse lapilli aphiric (san+pyr). colour from light and ash layers. different types of grey to dark green and brown. ggrreeeenniisshh 16,070±170b juvenile clasts mixed in the same trachytic composition. sommal8 g/530ppuummiiccee layer. accidental lithics are lava vesuvius 17h and carbonate fragments. few pyroclastic flow deposits in proximal areas. pyroclastic fall deposit comprises a white pumice: highly vesicular, white pumice basal layer followed by almost aphiric (san+pyr), trachytic ppoommiiccii ddii a black scoriae upper layer. accidental composition. black scoriae: somma18,300±180a lithics are lava and carbonate moderately vesicular, aphiric, latitic 595-17h bbaassee fragments. some pyroclastic composition. vesuvius flow deposits in proximal areas. segue table 1 96 eruptions (andronico & cioni, 2002; cioni et al., 2000). the correlation of layer l10 to the sarno eruption was questioned by sulpizio et al. (2003), on the basis of the attribution of the sarno deposits to the distal products of the pomici di base eruption (bertagnini et al., 1998; andronico et al., 1995; 1996). indeed, the layer l10 can be correlated to the tau1-e eruption , very similar in lithology (light and dark coloured juvenile fragments; table 2), chemical composition (trachytes-latites; table 3) and age (about 24 ka) to the previously attributed sarno eruption. furthermore, the codola eruption, previously reported as a plinian eruption of sommavesuvius (santacroce, 1987), has been recently attributed to the activity of phlegrean fields, on the basis of lithology and dispersal of fall deposits (andronico et al., 1995; 1996; sulpizio et al., 2003). the recognition of tephra layers in cores from the other lakes is more sporadic and limited to the somma-vesuvius eruption of avellino (lago di nemi and lago di albano), biancavilla ignimbrite (lago di albano, lago di mezzano and in the slope deposits on the flanks of the fucino basin) and neapolitan yellow tuff (valle di castiglione; fig. 3). tthhee mmaarriinnee rreeccoorrdd siani (1999) and siani et al. (2001; 2003) provided a detailed study and correlation of 11 tephra layers of the last 18 ka from a core located in the adriatic sea (md90-917; fig. 1). three of these tephra layers belong to the eruptions of agnano m. spina (tephra ams/pf), agnano pomici principali (tephra c1) and biancavilla ignimbrite (tephra et1/y1) previously recognised in marine cores (keller et al., 1978; paterne et al., 1988; vezzoli, 1991; calanchi et al., 1998). a fourth tephra of rhyolitic composition (tephra e1) has been correlated to the gabellottofiumebianco eruption of lipari (eolian islands) on the basis of chemistry and chronology. the other seven tephra layers have been for the first time correlated to terrestrial proximal deposits, on the basis of their chemistry, lithology and chronology (table 1). two of them (tephra 595-17 and 530-17) have been related to the pomici di base (santacroce, 1987; bertagnini et al., 1998) and greenish (santacroce, 1987; cioni et al., 2003b) eruptions of somma-vesuvius respectively, whereas the tephra layer 275-17 has been related to the activity of palinuro seamount (fig. 4 and table 1). the other four tephra layers have been related to the phlegrean fields activity. in particular the tephra layer 140-17 has been correlated to the astroni eruption, while tephra layers 39517, 405-17, 435-17 clustered in a stratigraphic position very close to the previously recognised c2 tephra (paterne et al., 1988; calanchi et al., 1998), related to the neapolitan yellow tuff eruption (paterne et al., 1988). indeed, the accurate sampling of the core (every 3 cm; siani, 1999; siani et al., 2003) allowed to recognise three difr. sulpizio et al. figure 3 schematic correlation among tephra layers recognised in the lacustrine cores considered in this study. see fig. 1 for locations. * recognised in the detrital deposits on the flanks of fucino basin (narcisi, 1993). l a g o g ra n d e d i m o n tic ch io v ic o m e zz a n o v a lle d i c a st ig lio n e , 97a review of tephrostratigraphy ... table 2 chronology and main lithological characteristics of the proximal terrestrial deposits of the 18.3-65ka time span correlated to the marine and lacustrine tephra layers. m14c age from paterne et al. (1988); n14c age from sulpizio et al. (2003); o 14c and 39ar/40ar ages from deino et al. (1994) and ton-that et al. (2001); in italic are shown the ages calculated by interpolation of 14c data in marine cores (paterne et al. 1988; paterne & guichard, 1993). f-keller et al. (1978); g-narcisi et al. (1996); h-siani et al. (2003); l-paterne et al. (1988), paterne & guichard (1993), paterne (1985); p-calanchi et al. (1994). characteristics of proximal deposits and lithology of juvenile fragments of tau1-d, e, smp1-a, c, d, e, ca1-a, sc2-a, sa3-a, sa2-a, codola and s. lucia from sulpizio et al. (2003); solchiaro/taurano from di girolamo & stanzione (1973) and zanchetta et al. (2000); schiava pumice from zanchetta et al. (2000); campanian ignimbrite from rosi & sbrana (1987); green tuff of pantelleria from mahood & hildreth (1986); green tuff of ischia from vezzoli (1988). eerruuppttiioonn aaggee cchhaarraacctteerriissttiiccss ooff pprrooxxiimmaall lliitthhoollooggyy ooff jjuuvveenniillee ffrraaggmmeennttss iinnffeerrrreedd tteepphhrraa ((kkaa)) ddeeppoossiittss ssoouurrccee llaayyeerr massive layer formed by well poorly vesicular , sub-aphiric ssoollcchhiiaarroo 19.62±0.27m sorted, black, scoriaceous, coarse (amph+pyr+san). inner colour: n3procida c4l //ttaauurraannoo lapilli. sparse accidental lithics, dark grey; outer colour: n5-medium island mainly lava fragments. grey. latitic chemical composition. basal layer formed by light light coloured pumice: moderately coloured pumice followed by an vesicular, almost aphiric (amph+pyr). upper layer of black scoriae. colour n5, medium grey. trachytic phlegrean l10g ttaauu11--ee 24 accidental lithics are scarce and chemical composition. black scoriae: mainly are lava fragments. moderately vesicular, almost aphiric fields c6l (amph+pyr). colour n3, dark grey. latitic chemical composition. double alternation of fine grained, highly to medium vesicular, aphiric, vesicular ash and light to dark grey pumice and scoria. presence of pumice lapilli layers. fine grained banded pumice fragments. phlegrean l11g ccooddoollaa 25.1±0.4m pumice lapilli scatterly occur inside color:5y 8/1yellowish grey; fields c8l the ash layers. accidental lithics are n4-medium dark grey. dark coloured lava fragments. trachytic chemical composition. massive ash with sparse, light grey highly vesicular, aphiric, pumice. phlegrean ssmmpp11--ee 25.82±0.27n pumice lapilli. absence of coarse color:5y 8/1-yellowish grey. y3f accidental lithic fragments. trachytic chemical composition. fields massive pyroclastic fall deposit of highly vesicular, aphiric pumice. light brown pumice lapilli. sparse inner colour: 5y 8/1-yellowish grey; phlegrean ttaauu11--dd 27.8 accidental lithics mainly are lava outer colour: 10yr 8/2-very pale orange. fields 332-04l fragments. trachytic chemical composition massive pyroclastic fall deposit of highly vesicular, porphyritic brown, scoriaceous, coarse lapilli (pyr+bt+san) scoria. presence of with good sorting. sparse cumulate xenoliths. inner colour: 5y phlegrean ssmmpp11--dd 28.5 accidental lithics, mainly are lava 6/1-light olive grey; outer colour: fields 360-18l fragments. 10yr 6/2-pale yellowish brown. latitic chemical composition alternation of 5 fine grained, light highly microvesicular, sub-aphiric sscchhiiaavvaa brown, vesicular ash and 4 well (bt+san), pumice. colour: n8-very ischia 3366 sorted, light grey pumice lapilli light grey. trachytic chemical c-9l ppuummiiccee layers. accidental lithic are scarce composition island and are lava fragments. basal pyroclastic fall layer followed by pumice fragments are highly impressive pyroclastic flow deposits vesicular, moderately porphyritic ccaammppaanniiaann which form the ignimbrite s.s. large (san+bt). colour: from pinkish-brown phlegrean iiggnniimmbbrriittee 37-41o variability of juvenile fragments, which to light grey. trachytic chemical c13al comprise light coloured pumice and composition fields dark, porphyritic scoriae. accidental lithics are mainly lava fragments basal massive layer of pumice highly vesicular, sub-aphiric lapilli that graded into an alternation (san+bt+pyr), pumice. tubular phlegrean ssmmpp11--cc ~40 of ash and lapilli. accidental lithics vesicles. colour: 5y 6/4-dusty yellow. fields c13bl are scarce and are lava fragments trachytic chemical composition massive, well to moderately sorted highly vesicular, sub-aphiric ischia layer of greyish pumice lapilli. (san+bt+pyr), pumice. tubular island/ ssmmpp11--aa 4422 accidental lithics are scarce and vesicles. colour: 5y 6/1-light olive phlegrean c14l are lava fragments. grey. trachytic chemical composition fields alternation of pyroclastic fall and ggrreeeenn ttuuffff 45 flow deposits, sometimes welded pantelleria y6f in proximal areas. alternation of brown fine grained highly vesicular, sub-aphiric (san+bt), ash and light grey pumice lapilli pumice. tubular vesicles. inner layers. fine grained pumice lapilli colour: 5y 6/1-light olive grey; outer phlegrean ssaannttaa lluucciiaa 47.5±2.6n scatterly occur inside the ash colour; 10yr 6/2-pale yellowish fields c15l layers. accidental lithics are dark brown. trachytic chemical coloured lava fragments. composition. ferent peaks of homogeneous glass shards in the 12-13 ka time span, correlable to the proximal pyroclastic deposits of lagno amendolare (tephra 435-17), gm1 (tephra 405-17) and neapolitan yellow tuff (tephra 39517; table 1). the record of tephra layers younger than 18 ka is completed by the recognition of e2, v1, avellino and z-1, respectively related to pollara eruption from salina island (eolian archipelago; paterne et al., 1988), mercato, avellino and ad 79 eruptions from sommavesuvius (keller et al., 1978; paterne et al., 1988; fontugne et al., 1989). anyway, the correlations regarding two of these tephra layers need some further comments. tephra layer z-1 has been related to the ad 79 eruption from somma-vesuvius, even if keller et al. (1978) reported a possible correlation with the avellino eruption from somma-vesuvius (3.8 ka; cioni et al., 1995; 2000). anyway, mineralogical characteristics of tephra layer z-1 (presence of melanite and leucite; keller et al., 1978) rules out the possible correlation with avellino deposits, characterised by the presence of scapolite and nepheline (cioni et al., 2000). up to now the tephra layers rf93-30 (530), recognised in the adriatic sea (calanchi et al., 1998), has not been correlated to a precise somma-vesuvius explosive event due to its chemical similarity to both ad 79 and avellino products (calanchi et al., 1998). indeed, both eds chemical analyses of proximal deposits (cioni et al., 2000), age of rf93-30 (530) tephra layer (>3660±100 yr bp; calanchi et al., 1998) and diversity in dispersal of fall deposits (ne for avellino, se for ad 79 deposits; cioni et al., 2000; sigurdsson et al., 1985) support the correlation of rf93-30 (530) tephra layer to the avellino eruption. the correlation of many of the tephra layers older than 18 ka with terrestrial deposits still remains difficult, with the only exceptions of the solchiaro eruption from procida island (tephra layer c4; paterne et al., 1988; paterne & guichard,1993), campanian ignimbrite eruption from phlegrean fields (tephra layer y5/c13; keller et al., 1978; paterne et al., 1988; ton-that et al., 2001) and green tuff from pantelleria (tephra layer y6; keller et al., 1978). several authors (keller et al., 1978; paterne et al.,1988; paterne & guichard,1993; calanchi et al., 1994; 1998) correlated numerous tephra layers of age between 18 and 65 ka from tyrrhenian and adriatic sea cores (fig. 4) to different sources such as etna, eolian islands and ischia volcanoes, usually grouping together phlegrean fields and somma-vesuvius due to the chemical homogeneity of their products. however, the contribution of somma-vesuvius to the tephra record in the 18-65 ka is negligible, as testified by the lack of pyroclastic deposits of comparable age in the terrestrial record (fig. 2). on the basis of lithology, chemistry and chronology (tables 2 and 3), sulpizio et al. (2003) correlated fourteen tephra layers of age between 18 and 65 ka to terrestrial pyroclastic deposits from phlegrean fields, ischia, and dubitatively sommavesuvius (fig. 5). these correlations allow to unravel some important points about the existence of many primary vs secondary tephra layers in this time span (questioned by mccoy & cornell, 1990 and narcisi & vezzoli, 1999) and the attribution of the tephra layers to precise volcanic sources, in many cases different to the previously hypotised (keller et al., 1978; paterne et al.; 1988; paterne & guichard, 1993; calanchi et al., 1994). in particular, tephra layers c6 and c8 (paterne, 1985; paterne et al., 1988) have been correlated to the pyro98 eerruuppttiioonn aaggee cchhaarraacctteerriissttiiccss ooff pprrooxxiimmaall lliitthhoollooggyy ooff jjuuvveenniillee ffrraaggmmeennttss iinnffeerrrreedd tteepphhrraa ((kkaa)) ddeeppoossiittss ssoouurrccee llaayyeerr massive, well to moderately sorted highly vesicular, sub-aphiric layer of greyish brown coarse (san+bt+pyr), coarse pumice lapilli. pumice lapilli. accidental lithics tubular vesicles. inner colour: 5y phlegrean ccaa11--aa 51 are scarce and are lava fragments. 6/1-light olive grey; outer colour: fields c16l 10yr 6/2-pale yellowish brown. trachytic chemical composition mainly pyroclastic flow deposits, from highly to incipiently vesicular, sometimes welded in proximal porphyritic (san+pl+pyr). colour from ischia l14g ggrreeeenn ttuuffff 55 areas, rich in accidental lithics and whitish to yellowish. trachytic blocks of poorly vesicular juvenile chemical composition. island fragments. alternation of grey, fine grained fine grained, highly vesicular, sub pumice lapilli and brown coarse aphiric (bt), pumice lapilli. elongated ischia sscc22--aa 57 ash layers. accidental lithics are shape. tubular vesicles. colour: 5gy c(i)6l scarce and are lava fragments. 6/1-greenish grey. trachytic chemical island composition. basal layer formed by brown, fine highly vesicular, sub-aphiric (bt), ash followed by a well-sorted, pumice lapilli. colour 5y 6/4-dusty phlegrean c18l/y7f/ ssaa33--aa 60.3 massive, yellowish brown pumice yellow. trachytic chemical lapilli layer. accidental lithics are composition. fields t003p scarce and are lava fragments. basal, dark coloured pumice lapilli highly vesicular, sub-aphiric layer overlaid by black, vesicular, (bt+px+san), pumice. inner colour: 5y sommassaa22--aa 62.3 fine ash with sparse fine pumice 4/1-olive grey; outer colour: 10yr 666-04l lapilli. accidental lithics are 6/2-pale yellowish brown. trachytic vesuvius reddish lava fragments. chemical composition. segue table 2 r. sulpizio et al. 99 ee rruu pp ttiioo nn tt aa uu 11 --ee ll 11 00 bb st . d e v. ll 11 00 aa st . d e v. cc 66 cc oo dd oo llaa st . d e v. ll 11 11 st . d e v. cc 88 w h ite a b la ck a l . g re ya (n = 2 ) d . g re ya s io 2 6 3 .3 6 1 .7 8 6 4 .2 3 1 .2 3 6 3 .8 7 0 ,0 5 6 3 .5 8 5 8 .7 5 0 .0 4 6 0 .7 3 6 0 .0 1 0 ,0 5 6 0 .4 t io 2 0 .5 6 0 .6 0 .3 9 0 .1 2 0 .4 1 0 .1 1 0 .3 2 0 .6 4 0 .0 1 0 .5 7 0 .5 5 0 .2 8 0 .2 3 a l 2 o 3 1 8 .0 2 1 9 .1 3 1 8 .3 6 0 .2 6 1 8 .2 4 0 .2 3 1 9 .4 1 8 .3 6 0 .0 2 1 8 .1 1 2 0 .5 6 1 .3 1 2 0 .0 2 f e 2 o 3 3 .2 1 3 .6 2 3 .2 6 0 .3 6 3 .2 1 0 .2 4 2 .6 6 4 .8 5 0 .4 4 4 .2 1 2 .7 9 1 .2 6 2 .6 9 m n o 0 .1 5 0 .1 6 0 .1 6 0 .1 2 0 .1 0 .1 0 .1 4 0 .0 1 0 .1 3 0 .0 9 0 .0 7 m g o 0 .7 0 .6 5 0 .3 8 0 .1 8 0 .5 0 .2 2 0 .3 4 5 1 .1 2 0 .3 3 0 .8 6 0 .4 7 0 .4 3 0 .0 4 c a o 2 .2 9 2 .4 2 .1 3 0 .2 2 .0 2 0 .1 9 2 .2 4 5 4 .8 0 .3 8 3 .9 3 4 .7 3 0 .9 2 3 .1 5 n a 2 o 4 .3 8 4 .0 5 2 .1 4 0 .2 9 2 .3 9 0 .4 1 3 .3 8 3 .5 5 0 .6 6 3 .7 8 2 .9 2 0 .5 2 4 .3 8 k 2 o 7 .3 4 7 .5 3 8 .6 3 0 .6 3 8 .9 5 0 .4 5 8 .0 7 7 .7 1 .8 6 7 .5 6 7 .5 8 1 .3 6 9 .0 5 p 2 o 5 0 .0 6 0 .0 7 0 .3 5 0 .2 3 0 .2 8 0 .1 5 0 .1 3 0 .0 3 0 .1 1 0 .2 6 0 .1 7 l .o .i . 4 .7 9 4 .5 2 3 .6 7 2 .6 5 6 .9 9 1 .5 5 3 .5 8 0 .0 6 2 .7 4 4 .6 2 1 .9 4 n b 6 7 7 4 5 3 9 5 4 z r 4 5 8 5 0 4 3 0 9 3 0 3 1 5 y 3 8 4 3 3 1 4 3 0 s r 8 6 1 9 1 6 1 1 2 5 9 5 1 0 3 7 r b 2 3 4 2 4 2 2 8 4 1 6 2 8 3 c e 2 7 0 2 8 4 1 3 3 1 2 1 4 2 b a 1 0 3 6 1 0 9 1 1 8 1 7 4 0 0 1 5 0 6 l a 1 5 2 1 4 7 7 3 6 7 4 n i 3 4 6 1 6 c r 3 4 1 0 2 7 v 6 1 6 6 9 1 1 7 7 8 c o 4 5 9 1 6 t o ta l 1 0 0 .0 1 9 9 .9 9 1 0 0 .0 3 9 9 .9 7 9 9 .9 9 1 0 0 .0 1 9 9 .9 9 9 9 .9 6 9 9 .9 6 t o ta l a lk a li 1 1 .7 2 1 1 .5 8 1 0 .7 7 1 1 .3 4 1 1 .4 5 1 1 .2 5 1 1 .3 4 1 0 .5 1 3 .4 3 k 2 o /n a 2 o 1 .6 8 1 .8 6 4 .0 3 3 .7 4 2 .3 9 2 .2 6 2 2 .6 2 .0 7 ss mm pp 11 --ee yy 33 tt aa uu --dd aa 33 33 22 --00 44 ss mm pp 11 --dd st .d e v. 33 66 00 --11 88 xx rr ff ee dd ss (n = 2 0 ) 6 2 .0 2 6 2 .2 6 6 3 .8 1 6 3 .4 8 5 6 .4 5 5 9 .7 8 0 .7 3 6 0 .2 7 0 .3 5 0 .4 3 0 .4 9 0 .3 1 0 .7 4 0 .1 8 0 .1 1 0 .5 3 1 8 .6 6 1 8 .4 1 8 .0 7 1 9 .3 1 1 5 .4 1 1 8 .1 0 .3 6 1 9 .0 9 3 .2 3 .5 9 3 .0 6 2 .9 4 6 .0 5 4 .2 6 0 .3 4 .1 5 0 .1 5 0 .1 1 0 .1 3 0 .1 2 0 .0 6 0 .0 8 0 .7 0 .9 3 0 .5 8 0 .3 8 4 .8 3 1 .2 0 .1 9 0 .1 6 2 .4 2 .6 9 1 .8 3 2 .3 1 7 .8 8 3 .8 0 .4 2 3 .6 4 4 .2 4 .1 3 3 .9 6 3 .1 2 2 .4 6 4 .3 1 0 .1 9 3 .6 8 .2 7 .4 7 7 .9 8 8 .1 2 5 .7 4 8 .2 9 0 .2 7 8 .5 2 0 .1 1 0 .0 7 0 .3 3 2 .8 4 .5 4 4 .2 1 1 .9 9 6 8 2 8 5 4 2 2 3 5 4 1 2 6 3 4 4 5 5 5 2 7 7 2 1 7 2 2 9 9 6 2 7 4 1 0 6 3 1 3 1 4 8 3 7 3 5 2 0 2 5 6 1 5 3 5 2 1 9 9 .9 9 1 0 0 9 9 .9 8 9 9 .9 7 1 0 0 .0 1 1 0 0 9 9 .9 6 1 2 .4 1 1 .6 1 1 .9 4 1 1 .2 4 8 .2 1 2 .6 1 2 .1 2 1 .9 5 1 .8 1 2 .0 2 2 .6 2 .3 3 1 .9 2 2 .3 7 t a b le 3 c h e m ic a l a n a ly se s o f th e p ro xi m a l p yr o cl a st ic d e p o si ts o ld e r th a n 1 8 .3 k a o f th e c a m p a n ia n a re a a n d t h e c o rr e la te d t e p h ra l a ye rs . e d s a n a ly se s fo r a ll la cu st ri n e a n d m a ri n e t e p h ra la ye rs . a -x r f c h e m ic a l a n a ly se s. n = n u m b e r o f a n a ly se d s a m p le s. 33 aa )) a review of tephrostratigraphy ... 100 ee rruu pp ttiioo nn ss cchh iiaa vvaa aa st . d e v. cc 99 ss mm pp 11 --cc aa cc 11 33 bb ss mm pp 11 --aa aa cc 11 44 ss .. ll uu ccii aa aa st . d e v. cc 11 55 cc aa 11 --aa aa st . d e v. cc 11 66 st . d e v. ss cc 22 --aa aa st . d e v. cc ((ii ))66 (n = 3 ) (n = 8 ) (n = 4 ) (n = 2 ) s io 2 6 7 .7 1 0 .4 1 6 6 .1 6 6 0 .7 1 6 0 .9 8 6 2 .2 4 6 3 .1 4 5 9 .7 4 0 .3 5 6 1 .3 5 6 1 .0 9 1 .1 4 6 1 .6 3 0 .9 3 6 3 .4 6 0 .3 6 6 4 .3 7 t io 2 0 .2 1 0 .0 1 0 .2 4 0 .4 8 0 .3 4 0 .4 7 0 .2 8 0 .5 1 0 .0 3 0 .2 9 0 .4 6 0 .0 5 0 .3 1 0 .0 9 0 .5 3 0 0 .1 3 a l 2 o 3 1 6 .4 2 0 .3 4 1 7 .8 2 1 8 .5 4 1 9 .3 4 1 9 .2 1 1 9 .2 1 8 .6 2 0 .6 9 1 9 .1 3 1 8 .0 7 0 .0 8 1 9 .0 9 0 .2 2 1 7 .7 8 0 .2 3 1 8 .5 5 f e 2 o 3 2 .2 7 0 .0 4 1 .9 8 3 .7 2 3 .2 5 3 .8 4 2 .5 8 5 .0 3 0 .2 5 3 .0 6 4 .4 5 0 .5 9 2 .9 7 0 .4 7 3 .8 6 0 .0 4 2 .3 9 m n o 0 .1 4 0 0 .1 5 0 .2 4 0 .1 5 0 .0 1 0 .1 4 0 0 .3 2 0 .0 1 m g o 0 .4 1 0 .0 1 0 .0 4 0 .5 8 0 .5 5 0 .5 6 0 .1 3 1 .2 4 0 .1 4 0 .1 3 1 .0 9 0 .1 8 0 .1 4 0 .0 7 0 .5 1 0 .0 4 0 .0 1 c a o 2 .2 9 0 .0 7 2 .2 6 3 .4 7 2 .5 2 1 .9 1 .5 4 3 .4 0 0 .1 9 1 .9 5 3 .0 7 0 .3 9 1 .8 4 0 .2 9 1 .6 2 0 .0 4 1 .5 6 n a 2 o 3 .7 9 0 .0 6 3 .6 3 .5 5 3 .4 4 .9 2 5 .7 6 3 .2 6 0 .3 4 6 .5 2 3 .3 7 0 .0 4 6 .2 7 0 .4 9 5 .5 9 0 .0 6 4 .9 9 k 2 o 6 .7 3 0 .1 1 7 .8 5 8 .7 3 9 .6 6 .5 5 7 .3 4 7 .8 8 0 .3 4 7 .5 3 8 .1 2 0 .2 1 7 .7 2 0 .5 4 6 .3 2 0 .1 7 .9 8 p 2 o 5 0 .0 3 0 0 .0 6 0 .0 7 0 .1 7 0 .0 2 0 .1 5 0 .0 4 0 .0 4 0 l .o .i . 3 .8 0 .0 8 3 .5 4 5 .3 9 3 .9 8 0 .6 1 4 .0 5 0 .5 4 4 .5 6 0 .1 1 n b 4 8 3 6 0 1 1 4 4 7 4 4 8 2 1 5 7 2 z r 3 9 3 1 0 3 8 5 7 0 1 3 2 5 1 6 3 3 5 1 3 1 0 2 6 8 y 2 7 2 3 5 6 0 3 0 3 3 2 1 9 9 1 s r 1 8 9 7 7 3 6 5 6 7 3 6 5 0 7 3 0 3 3 3 5 1 3 r b 3 8 3 8 3 1 7 3 5 2 2 6 1 1 9 2 5 9 1 3 4 2 7 4 c e 1 4 7 5 1 5 8 2 4 0 1 5 4 1 2 1 5 3 3 4 6 8 1 1 b a 9 2 3 7 6 8 1 8 1 2 0 3 1 6 8 1 0 7 3 7 2 3 4 1 0 l a 9 0 2 9 1 1 3 1 8 5 8 8 6 4 2 5 2 3 n i 4 2 4 4 6 3 5 2 4 1 c r 4 1 4 2 9 4 7 3 3 2 v 1 7 1 5 8 1 7 8 4 8 6 8 1 4 1 5 1 c o 3 1 5 5 1 0 1 8 2 5 1 t o ta l 1 0 0 9 9 .9 5 9 9 .9 9 9 9 .9 8 1 0 0 9 9 .9 7 1 0 0 9 9 .9 6 1 0 0 9 9 .9 7 1 0 0 .0 1 9 9 .9 8 t o ta l a lk a li 1 0 .5 3 0 .1 4 1 1 .4 5 1 2 .2 8 1 3 1 1 .4 7 1 3 .1 1 1 .1 3 0 .6 4 1 4 .0 5 1 1 .4 9 0 .2 2 1 3 .9 9 1 1 .9 1 0 .1 6 1 2 .9 7 k 2 o /n a 2 o 1 .7 8 0 .0 3 2 .1 8 2 .4 6 2 .8 2 1 .3 3 1 .2 7 2 .4 3 0 .1 8 1 .1 5 2 .4 1 0 .0 6 1 .2 3 1 .1 3 0 1 .6 st .d e v. ss aa 33 --aa aa cc 11 88 ss aa 22 --aa aa st .d e v. 66 66 66 --00 44 (n = 2 ) (n = 2 ) 1 .0 8 6 2 .3 6 1 .3 6 5 9 .2 4 0 .4 7 6 0 .8 0 .1 3 0 .4 5 0 .3 1 0 .6 6 0 0 .3 6 0 .0 7 1 8 .3 2 1 8 .9 6 1 7 .6 4 0 .1 1 9 .6 4 0 .2 2 3 .5 7 3 .1 7 5 .6 4 0 .2 6 3 .0 9 0 .1 8 0 .1 4 0 0 .0 2 0 .6 3 0 .3 2 2 0 .4 2 0 .0 9 0 .1 6 2 .1 5 2 .7 8 4 .7 9 0 .1 6 2 .5 9 0 .9 9 3 .9 9 3 .4 3 .3 1 0 .5 4 .9 3 0 .4 2 8 .3 4 9 .6 8 6 .3 6 0 .4 1 8 .4 7 0 .0 6 0 .2 3 0 .0 3 3 .9 2 3 .0 4 0 .2 1 6 4 4 5 7 4 0 4 3 3 2 5 0 4 1 3 6 3 3 9 6 8 2 6 2 9 2 7 6 2 0 8 1 1 2 1 0 1 6 5 2 4 1 4 9 1 1 5 8 1 4 1 1 1 4 8 7 2 0 3 1 0 5 2 2 7 2 7 3 4 1 0 6 1 5 1 3 1 9 9 .9 9 9 9 .9 8 1 0 0 9 9 .9 7 1 2 .3 3 1 3 .0 8 9 .6 7 0 .0 8 1 3 .4 2 .0 9 2 .8 5 1 .9 5 0 .4 2 1 .7 2 s e g u e t a b le 3 33 bb )) r. sulpizio et al. clastic fall deposits of tau1-e and codola (table 2) respectively, while the widely dispersed y3 tephra layer (keller et al., 1978) has been correlated to the co-ignimbrite deposit smp1-e, dated at 25.82±0.27 ka (tables 2 and 3). the attribution of tephra layer c8 to codola eruption needs some comments. this tephra layer was recognised in cores ket 8004, 8011 and 8218 from tyrrhenian and adriatic seas, and dated at 26.7±0.8 ka (paterne, 1985). anyway, in more recent papers (paterne et al., 1988; paterne & guichard, 1993) c8 101 figure 4 schematic correlation among tephra layers recognised in the marine cores considered in this study. see figure 1 for locations. a review of tephrostratigraphy ... tephra layer is not reported, due to the misleading attribution of tephra layer c10 to the campanian ignimbrite eruption made by paterne et al. (1988) and the following “forced” adjustment of the stratigraphy of core ket 8004 on the basis of a c10 age of 33.5 ka (paterne et al. , 1988). indeed, new 14c and 39ar/40ar data aged the terrestrial campanian ignimbrite deposits to about 37-39 ka (deino et al., 1994; de vivo et al., 2001), in agreement with the new correlation of these deposits to tephra layer c13 (dated at about 41 ka; ton-that et al., 2001). on the basis of these evidences the original stratigraphy of core ket 8004 reported by paterne (1985) and age of tephra layer c8 of 26.7±0.8 ka have been considered correct and adopted for the correlation with proximal deposits. similar problems affect also the tephra layers 332-04 and 360-18, which have been correlated to the tau1-d and smp1-d pyroclastic fall deposits. these two tephra layers were dated at about 33.5-33.7 ka (paterne et al., 1988), but these ages must not be considered correct, being influenced by the double error introduced by the correlation of layer c10 to the campanian ignimbrite deposits and to the age of 33.5 ka attributed to its proximal terrestrial deposits (paterne et al., 1988). on the basis of these considerations the original ages of 27.8 and 28.5 ka for tephra layers 332-04 and 36018 (paterne, 1985) have been adopted. moreover, an accurate inspection of chemical and stratigraphic data of c13 tephra layer shows the coexistence of at least two different tephra with similar chemical composition (peralkalic trachyte and trachyte; paterne, 1985; paterne et al., 1988), here labelled c13a and c13b (tables 2 and 3). indeed, only the c13a tephra layer belong to the campanian ignimbrite deposits, while the c13b tephra layer has been correlated to 102 figure 5 schematic correlation among terrestrial deposits and tephra layers recognised in lacustrine and marine cores. dashed lines indicate the lack of tephra layer in lacustrine or marine cores. on the left of the terrestrial record column are shown the deposits from phlegrean fields activity, whereas on the right are shown the deposits of somma-vesuvius (plain text), ischiaprocida (italic text) and etna-eolian islands-palinuro seamount-pantelleria (underlined italic text). the grey dashed box indicates the uncertainties in the age of campanian ignimbrite deposits. r. sulpizio et al. the smp1-c pyroclastic fall deposit, emplaced very close to the campanian ignimbrite eruption (sulpizio et al., 2003). the recognition of smp1-c deposits can also help in the unravelling the discussion about the single or multiple occurrence of campanian ignimbrite(s) (paterne et al., 1988; scandone et al., 1991; narcisi & vezzoli, 1999). as shown for the c2 tephra layer (siani et al., 2003), this is probably due to the clustering of different large explosive eruptions of similar chemical composition occurred in a relatively short time span, which frequently results in a thick, single, marine tephra layer. the correlation of tephra layer c9 (dated at 36 ka; paterne & guichard, 1993) to the schiava eruption is supported by the most evolved chemical composition in the whole set of data shown by both deposits (table 3), while tephra layer c14 has been correlated to the smp1-a pyroclastic fall deposit (tables 2 and 3). the c15-c18 tephra layers were grouped in the green tuff series by paterne et al. (1988), and attributed to the activity of the ischia island. indeed, only the tephra layer c17 can be correlated to the green tuff eruption of ischia, while the other tephra layer have been correlated to terrestrial proximal deposits on the basis of chronology, lithology and chemical composition (tables 2 and 3). among them the only tephra layer correlable to ischia activity is the c(i)6, dated at 57 ka (paterne et al., 1988), which correspond to the sc2-a pyroclastic fall deposit (tables 2 and 3). the other tephra layers of the green tuff series have been correlated to the explosive activity of phlegrean fields (table 2; sulpizio et al., 2003). in particular, c15 tephra layer has been correlated to the large explosive eruption of s. lucia, dated at 47.5±2.6 ka (sulpizio et al., 2003; table 2), while c16 tephra layer has a terrestrial counterpart in the ca1-a pyroclastic fall deposit (tables 2 and 3). tephra layer c18 appear very widespread in the central mediterranean cores, and correspond to the tephra layer 003 from odp leg 107-site 650 (calanchi et al., 1994), and to the tephra layer y7 (keller et al., 1978). it has an interpolated age of 60.3 ka (paterne et al., 1988; paterne & guichard, 1993) and corresponds to the terrestrial proximal deposit sa3-b (tables 2 and 3). finally, the oldest tephra layer correlated to a terrestrial counterpart is 666-04, dated at 62.3 ka by paterne et al. (1988), which corresponds to sa2 pyroclastic fall deposit (tables 2 and 3). ccoorrrreellaattiioonnss aammoonngg ddiiffffeerreenntt pprrooxxiieess figure 5 shows a schematic correlation among terrestrial, lacustrine and marine proxies. it represents an up-to-date, detailed chronostratigraphic scheme of the last 65 ka, useful for the correlation of different archives in the mediterranean region. seventeen tephra layers were correlated in the last 20 ka among the three proxies, while two tephra layers (ap1-2) were correlated between proximal terrestrial and lacustrine proxies. most of them are concentrated in the <4.5 ka and in the 10.5-20 ka time spans, with the occurrence of only two tephra layers (mercato and e1 tephra layers) in the 4.510.5 ka (fig. 5). other sixteen tephra layers were correlated in the 20-63 ka time span among terrestrial, marine and lacustrine proxies. a cluster of five tephra layers occurs between 24-27 ka, whereas ten tephra layers, almost regularly spaced, characterise the >35 ka time span (fig. 5). moreover, sources from neapolitan volcanoes dominated throughout the whole succession, with the occurrence of only two eolian (e1/gabellottofiumebianco and e2/pollara; paterne et al., 1988; calanchi et al., 1993; siani et al., 2001; 2003) and etnean (y1/et1/biancavilla ign.; keller et al., 1978; paterne et al., 1988) tephra. on the basis of the proposed correlations the dispersal areas of several of these tephra layers can be traced (figs. 6 and 7). these areas, even broadly defined and strongly dependent on the recognition of tephra in the marine and lacustrine cores, are generally in agreement with the main direction of dispersal of fall deposits of several well-known eruptions from sommavesuvius and phlegrean fields, such as ad 79, avellino, agnano m. spina, mercato, agnano p.p., greenish, pomici di base, tau1-e and s. lucia (figs. 6 and 7). in some cases, the dispersal areas indicate in figures 6 and 7 comprise sites (i.e. cores) where the tephra layer has not been recognised. several causes can account for this lack of recognition, such as settling of the marine tephra as multiparticle aggregates (carey, 1997), erosion due to bottom currents or coring process. on the other hand, pyroclastic fall deposits are frequently dispersed along a defined dispersal axis and the isopach maps enclose ellipse-shaped areas, even if changes in dispersal axis is possible in very distal areas (cas and wright, 1987). in this way, in figures 6 and 7 we traced the indicative dispersal areas on the basis of proximal isopachs, irrespective of the presence or not of the tephra layer in all the cores enclosed. instead, broader and irregular dispersions characterise the tephra layers correlated to single (i.e. campanian ignimbrite) or clusters (biancavilla, nyt) ignimbrite-forming eruptions (fig. 6 and 7), due to the different eruptive dynamic and dispersal of volcanic clouds not linked to large convective columns (cas and wright, 1987). ccoonncclluuddiinngg rreemmaarrkkss the proposed correlations highlights only part of the tephra layer record reported for the central mediterranean region (i.e. keller et al., 1978; paterne et al., 1988; vezzoli, 1991; narcisi, 1996; calanchi et al., 1998; wulf et al., 2001), but more work is necessary to reach a comprehensive correlation among terrestrial, lacustrine and marine records. the correlations proposed in this work, although being as comprehensive as possible, intend to be preliminary. indeed, it is only of transitory usefulness, because the knowledge of past activity for some italian volcanoes is in tumultuous growth and in the near future new data will be available. in particular, the knowledge of stratigraphy and chronology of tephra layers older than 18 ka of centralsouthern italy need to be supported by extensive studies on terrestrial records near volcanic centres. specific studies should be addressed in this direction and it should be a specific task since active volcanoes are often studied only in respect to recent activity for the obvious purpose of hazard assessment. 103a review of tephrostratigraphy ... 104 66)) r. sulpizio et al. 105 figure 6 and 7 maps showing selected dispersal areas inferred from the recognition of tephra layers in lacustrine and marine cores. for deposits from sustained columns (fall deposits) the dispersal area has been traced using an ellipse with the same eccentricity of the proximal isopachs and delimited with a dashed line. the dashed areas in the avellino, agnano p.p. and s. lucia maps indicate secondary lobes of dispersion of tephra. for co-ignimbrite deposit (neapolitan yellow tuffs, biancavilla ignimbrites and campanian ignimbrite) and for the gabellotto-fiumebianco eruption the shaded area indicates the present day limit of recognition of the respective tephra layers. proximal isopach maps from: ad 79-sigurdsson et al. 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(2003) the late pleistocene pyroclastic deposits of the southern campanian plain: insights on their sources and relationships with tephrostratigraphy. int. journ. earth sc. submitted ton-that t., singer b. & paterne m. (2001) 40ar/39ar dating of latest pleistocene (41 ka) marine tephra in the mediterranean sea: implications for global climate records. earth planet. sci. letts. 118844, 645658. vezzoli l. (1988) island of ischia. cnr quad. ric. sci. 111144((1100)), 230. vezzoli l. (1991) -tephra layers in bannock basin (eastern mediterranean). mar. geol. 110000, 21-34. watts w.a., allen. j. r.m. & huntley b. (1996) vegetation history and climate of the lastglacial period at laghi di monticchio, southern italy. quat. sc. rev. 1155, 133-153. wulf s. (2000) das tephrochronologische referenzprofil des lago grande di monticchio. phd thesis. universitat potsdam. in german. wulf s., brauer a., frank u., mingram j. & negendank j.f.w. (2001) detailed stratigraphy of the italian explosive volcanism in sediments of lago grande di monticchio. cities on volcanoes 2, auckland, new zealand, february 22-26th, 2001. poster with abstract. zanchetta g., di vito m., fallick a.e. & sulpizio r. (2000) stable isotopes of pedogenic carbonate from somma-vesuvius area, southern italy, over the last 18 ka: palaeoclimatic implications. j. quat. sc. 1155, 813-824. 108 ms. ricevuto il 20 novembre 2002 testo definitivo ricevuto il 3 giugno 2003 ms. received: november 20, 2002 final text received: june 3, 2003 r. sulpizio et al. imp. miola ppoolllleenn ddaattaa ffoorr aa bbiioossttrraattiiggrraapphhyy ooff llggmm iinn tthhee vveenneettiiaann ppoo ppllaaiinn aannttoonneellllaa mmiioollaa11,, ddiieeggoo aallbbaanneessee22,, ggiiaannnnaa vvaalleennttiinnii11,, lliivviioo ccoorraaiinn33 1 dipartimento di biologia – università di padova 2 dipartimento di geologia, paleontologia e geofisica – università di padova 3 dipartimento di statistica – università di padova abstract during the last forty years many works have been published on sedimentary sequences from the planitial area of north-eastern italy. many authors refer about stratigraphic sequences which contained peat layers at different depths from the ground level. radiocarbon dating of peats has been given ages ranging from 22,500 to 18,000 yr bp. the area with suitable conditions for the formation of peat, seems to cover all the venetian planitial area for a brief period of time during the lgm. we are interested in the microfossil content of lgm peats, because it can contribute to the definition of past local hydrological conditions. we would like to answer to the following questions: i) can we say that the same type of vegetation has formed the lgm peats? ii) can we hypothesize that the same hydrological conditions were established during lgm in the plain? iii) can we use the peat horizon as a biozone for the venetian plain? we approach the topic by analysing new pollen data of peat sediments from a coastal area at the north of the venice lagoon, by means of a new statistical method of data analysis, namely the nonparametric combination of dependent permutation (npc) tests (pesarin, 2001). the statistical analysis of pollen data does not include the pollen records from other sites (tab.1), since they are not entirely reported in literature; therefore a successful comparison was not achievable. the npc test results confirm that there aren’t significant differences between the peat sediments. hence we can assert that the area was mostly covered by cyperaceae and poaceae, and this confirm our hypothesis. some other herbaceous taxa were present and many taxa of fungi, algae and mosses. studies for the identification of the latter and other plant fragments are in progress and they will lead to a finer characterization of the plant community. riassunto elementi palinologici per una biostratigrafia dell’ultima espansione glaciale nella pianura padano-veneta. negli ultimi quarant’anni sono stati pubblicati molti risultati di ricerche su sequenze sedimentarie provenienti dall’area planiziale dell’italia nord-orientale. molti autori hanno segnalato la presenza di strati torbosi di un’età compresa tra i 22.500 e i 18.000 a b.p., a profondità diverse dal livello di campagna. ciò suggerisce l’ipotesi che condizioni adatte alla formazione di torbe si siano instaurate in un’area che copriva gran parte della pianura veneta per un breve periodo di tempo in corrispondenza dell’ultima massima espansione glaciale (lgm). lo studio dei microfossili vegetali contenuti nelle torbe può contribuire alla ricostruzione delle condizioni idrologiche in cui si formarono le torbe e a rispondere alle seguenti domande: i) un unico tipo di vegetazione ha formato le torbe lgm della pianura veneta? ii) possiamo ipotizzare che le stesse condizioni idrologiche si siano instaurate nella pianura durante l’ultima espansione glaciale? iii) l’orizzonte torboso può essere considerato una biozona per la pianura veneta? abbiamo iniziato ad affrontare queste problematiche analizzando nuovi dati pollinici ottenuti dall’esame di torbe estratte in quattro sondaggi eseguiti nell’area costiera a nord della laguna di venezia. i dati pollinici sono stati confrontati attraverso un nuovo metodo di analisi statistica, il nonparametric combination of dependent permutation (npc) tests (pesarin, 2001), al fine di verificare l’esistenza di differenze tra i contenuti pollinici dei diversi campioni torbosi. i dati pollinici di altri autori (tab.1) non sono stati compresi nell’analisi eseguita, perché riportati solo parzialmente negli articoli pubblicati. l’npc test non ha individuato differenze tra i dati pollinici delle torbe esaminate, quindi possiamo ipotizzare che l’area a nord della laguna di venezia fosse occupata da una comunità di piante erbacee produttrici di torbe, caratterizzata dalla prevalenza di cyperaceae e poaceae, dalla presenza di callitriche, caltha palustris, hydrocharis morsus-ranae, menyanthes trifoliata, lemna, myriophyllum verticillatum, nuphar luteum, potamogeton subg. p. type e da molti taxa di funghi, alghe e briofite. il riconoscimento di quest’ultimi, la cui analisi è tuttora in corso, sarà di ulteriore aiuto nella ricostruzione dell’intera comunità vegetale. parole chiave: pianura padano-veneta, analisi pollinica, npc test, ultimo massimo glaciale keywords: venetian-po plain, pollen analysis, npc test, last glacial maximum il quaternario italian journal of quaternary sciences 1166(1), 2003, 21-25 iinnttrroodduuccttiioonn during the last forty years many works have been published on sedimentary sequences from the planitial area of north-eastern italy. they report results of lithological, stratigraphical, geological and paleobiological studies (bertolani marchetti, 1967; bortolami et al., 1977; paganelli, 1996a; rizzi longo, 1996; aa. vv., 1999; serandrei barbero et al., 2001). these works have contributed to a better knowledge of the evolution of the area, during late quaternary. they show the importance of floodplain sediments as valuable sources of information for paleoenvironmental reconstruction. in the venetian alluvial plain the sedimentation has been greatly influenced by the evolution of the principal fluvial systems (adige, brenta, piave and tagliamento) and by the sea-level fluctuations (castiglioni & pellegrini, 2001; bondesan et al., 2002). moreover the continental sedimentary sequences from different sites of the plain cannot be easily correlated using lithological data. as far as it concerns the microfossil content of the sediments, it is quite poor in sands, silts and sometimes also in clays: therefore this excludes the use of a biostratigrapic approach to correlate these kinds of sediments. 22 a. miola et al. nevertheless, many authors refer about stratigraphic sequences, which contained peat layers at different depths from the ground level (bortolami et al., 1977; accorsi et al., 1984; castiglioni et al., 1987; paganelli et al., 1988; accorsi et al., 1989; marocco, 1989; calderoni et al., 1996; mullenders et al., 1996; paganelli, 1996b; miola & gallio, 1997; lezziero, 1999; iliceto et al., 2001; serandrei barbero et al., 2001). radiocarbon dating of peats has been given ages ranging from 22,500 to 18,000 yr bp, i.e. the period of peat sedimentation is the lgm (tab. 1). pollen content has been analysed in some of them, but pollen data have not been correlated at a regional scale. the area with suitable conditions for the formation of peat during the lgm, seems to cover all the venetian planitial area (fig. 1). studies on this topic are in progress at the dept. of geography (university of padova). if they confirm that peat layers have been formed during a brief period of time, as some radiocarbon dates seem to suggest, and in an extensive regional area, their deposition may be considered a stratigraphic event for the venetian plain. we are interested in the microfossil content of lgm peats. peat originates mostly from the remains of plant communities, that live in waterlogged conditions. the quality of water, i.e. its dissolved mineral salts content, and the hydrological conditions determine the types of vegetation that live in a peatland (goodwin, 1981). therefore, pollen and spore analysis of peat sediments and the identification of other plant fragments can contribute to the definition of past local hydrological conditions. we would like to answer to the following quefig. 1 location of sites where peat layers from 22,500 to 18,000 yr bp have been found. ubicazione dei siti nei quali è stata segnalata la presenza di strati torbosi di età compresa tra 22.500 e 18.000 anni bp. 1) bernascone (vr), 2) basso acquar, 3) orgiano (vi), 4) villaga barbarano (vi), 5) rubano (pd), 6) galzignano (pd), 7) padova, 8) alveo brenta (pd), 9) conca romea (ve), 10) motte di volpego (ve), 11) pozzo venezia 1bis (ve), 12) la fenice (ve), 13) punta sabbioni (ve), 14) sant’erasmo (ve), 15) treporti (ve), 16) fiorentina (ve), 17) palazzetto (ve), 18) ca’fornera (ve), 19) crosere (ud), 20) latisana (ud), 21) laguna di marano (ud). tab.1 peat layers and relative 14c dates in the venetian plain from literature. età 14c convenzionali di strati di torba rinvenuti nella pianura padanoveneta già pubblicati. ssiitteess ddeepptthh ffrroomm tthhee 1144cc ccoonnvveennttiioonnaall ppoolllleenn rreeffeerreenncceess ggrroouunndd lleevveell ((mm)) ddaattiinnggss ((yyrr bb..pp..)) aannaallyyssiiss bernascone (vr) 5.6-5.7 18,870 ± 300 + accorsi et al., 1989 basso acquar (vr) 16.0-21.0 18,800 ± 2000 + accorsi et al., 1984 orgiano (vi) 4.4-4.5 17,760 ± 160 + paganelli, 1996b villaga barbarano (vi) 6.05-6.25 19,250 ± 210 + paganelli et al., 1988 paganelli, 1996b rubano 5 (pd) 9.40-9.46 19,200 ± 250 castiglioni et al., 1987 rubano 4 (pd) 7.94-8.00 18,100 ± 700 castiglioni et al., 1987 padova c. scrovegni b 15.0 19,830 ± 220 iliceto et al., 2001 galzignano (pd) 3.3-3.4 19,000 ± 1200 + calderoni et al., 1996 miola & gallio, 1997 alveo brenta (pd) 15.5-15.9 20,250 ± 900 bortolami et al., 1977 motte di volpego (ve) 10.6 19,620 ± 315 + bortolami et al., 1977 bertolani marchetti, 1967 sant’erasmo (ve) 19.0-19.4 19,250 ± 300 bortolami et al., 1977 treporti (ve) 27.5 22,440 ± 500 bortolami et al., 1977 punta sabbioni (ve) 18.0-18.5 20,000 ± 400 bortolami et al., 1977 conca romea (ve) 13.2-13.4 20,950 ± 900 bortolami et al., 1977 conca romea (ve) 6.4-6.7 19,410 ± 800 bortolami et al., 1977 la fenice (ve) 12.0 20,120 ± 90 serandrei barbero et al. 2001 ponte moro 1 (ve) 10.19 19,700 ± 250 serandrei barbero et al. 2001 p.zo venezia 1bis (ve) 24.3 21,750 ± 730 + mullender et al., 1996 venezia 12.0-10.0 19,800 ± 250 lezziero, 1999 laguna di marano s9 22.0 20,200 ± 720 marocco, 1989 candelù (tv) 20.3-20.5 19,170 ± 400 bortolami et al., 1977 stions: i) can we say that the same type of vegetation has formed the lgm peats? ii) can we hypothesize that the same hydrological conditions were established during lgm in the plain? iii) can we use the peat horizon as a biozone for the venetian plain? the purpose of this work is to approach the topic by comparing pollen data from peat sediments using a suitable statistical method. we recently analysed pollen and spores content of peat from a coastal area at the north of the venice lagoon. peat samples from palazzetto (pal-1819, pal-1834, pal-2034, pal2039, pal-2049), fiorentina (fio-1988, fio-1992), and ca’ fornera (caf-1956, caf-1967, caf-1978, caf1989) have been drilled near the river piave, between san donà di piave (venezia) and the coast of the adriatic sea, at a depth of about 20 m from the ground level (bondesan et al., 2003). latisana samples (lat410, lat-420) have been drilled near the tagliamento river at a depth of about 4 m. latisana samples have been radiodated 18,100±100 yr bp (fontana, pers. comm.). radiodating of the other samples are in progress. all the samples are characterized by low percentages (<20%) of arboreal taxa, among which pinus is the most abundant, followed by betula, abies, picea, larix, ephedra and juniperus. boreal broadleaf plants are rare. the grasses are represented by local aquatic plants and by cyperaceae, poaceae, artemisia, chenopodiaceae, caryophyllaceae, asteraceae asteroideae and apiaceae. this fossil pollen assemblage is indicative of a very sparse arboreal vegetation, with cold-climate taxa and it is often correlated to the last pleniglacial period (paganelli, 1996a) we compared our pollen records by means of a new statistical method of data analysis, namely the nonparametric combination of dependent permutation (npc) tests (pesarin, 2001). this new method has been adopted because the data configuration is characterized by a relatively high number of variables, i.e. pollen taxa, compared to the number of statistical units, i.e. peat samples. in this situation a standard multivariate approach, as principal component analysis, is not appropriate and applicable and in general it does not permit any kind of decision on the problem of determining whether there is an equal distribution of pollen associations among the sites. moreover, a classical inferential approach as manova (multivariate analysis of variance), apart from the very strong assumption of normality, is itself not allowed with a relatively small sample size as in our case (pesarin, 2002). on the contrary, the npc methodology frees the researcher from stringent assumptions of parametric methods and allows a more flexible analysis by specifying both multivariate and univariate hypotheses. one of the most relevant features of npc test is that it does not need a modelling for dependence among variables. pollen records have been subdivided into three groups, ca’ fornera (n° of records = 4), 23pollen data for a biostratigraphy ... fiorentina-latisana (n° of records = 4) and palazzetto (n° of records = 5). the considered pollen taxa are 20, but some of them have been joined and rare taxa and spore types have not been included. pairwise comparisons between groups of the relative frequencies of taxa have been performed with the aim of determining whether an equal distribution of pollen association is supported or not by our data set. the statistical analysis of pollen data does not also include pollen records from other sites (tab.1), as they are not entirely reported in literature: hence a successful comparison was not achievable. ssttaattiissttiiccaall aannaallyyssiiss ooff ppoolllleenn ddaattaa our statistical analysis starts with a descriptive overview of collected data. table 2 shows the mean and the standard deviation of the relative frequencies for all the pollen taxa included in our analysis; they are divided by site and also pooled for all sites. for the most important taxon, i.e. cyperaceae, we also provide a frequency graph (fig. 2), where an equal table 2 descriptive statistics for all considered taxa within each site. statistiche descrittive per i taxa analizzati in ogni sito. fig. 2 frequency distribution of cyperaceae on the three sites. distribuzione di frequenza delle cyperaceae nei tre siti. 24 distribution among sites could be possible. by means of a boxplot (fig. 3) we also provide a visual measure of the pooled distribution for the most relevant taxa or group of taxa, that are pinus undiff., cyperaceae, poaceae and hydrophytes. a simple descriptive analysis is only the first step of the work but we are not able to take a decision concerning a possible equal distribution of the relative frequencies of taxa among the sites. for this purpose we perform a npc test analysis, considering each single taxon and the global distribution of all taxa considered together. the npc test hypothesis system can be expressed in the following formal form, where a and b represent two sites, and xi represents the frequency of a given taxon (the i-th). the null hypothesis h0 states an equal global (multivariate) distribution between the two groups of all taxa (letter xx bold) considered together. the global null hypothesis is broken down into a set of k (20 in our study) partial null subhypotheses h0i which states an equal single (univariate) distribution for the i-th taxon between the two groups. for a detailed introduction and explanation of npc test methodology we refer to pesarin (2001). npc test solutions are provided by the new and innovative statistical software npc test 2.0 (more details at www.methodologica.it) that implements the npc methodology offering both flexibility and a user-friendly interface. as result of npc analysis (tab. 3), we obtain for each pairwise comparison a set of 20 pvalues concerning with each taxon and finally another one pvalue relating to the global null hypothesis. we should remember that a p-value less than the adopted significance α-level (in our case 5%, i.e. 0.05) means that there is a significant difference in the frequency distribution between the groups. ccoonncclluussiioonnss the npc test results confirm that there aren’t significant differences between peat sediments of the three groups if we look at their pollen associations (all global p-value are greater than 0.05). therefore we can support our hypothesis, that a plant community mostly consisting of cyperaceae and poaceae covered the entire area. some other herbaceous taxa were present, e.g. callitriche, caltha palustris, hydrocharis morsus-ranae, menyanthes trifoliata, lemna, myriophyllum verticillatum, nuphar luteum, potamogeton subg. p. type and many taxa of fungi, algae and mosses. studies for the identification of the latter and other plant fragments are in progress and they will lead to a finer characterization of the plant community. our results agree with the literature, in fact pollen analyses in tab. 1, showed dominance of herbaceous plant pollen, mostly of cyperaceae and poaceae, but little information about the other herbaceous plants. our research is continuing with pollen and fungi, algae and bryophytes microfossils analysis of lgm peats from other sites of the venetian plain in padova and near treviso. fig. 3 relative frequencies distribution of the most relevant taxa. distribuzione delle frequenze dei taxa più rilevanti.{h0: [pa = pb ] = [xxa d = xxb ] ⇒ {h0: [ k i =1 xai d = xbi ] = k i =1 h0i h1: [pa pb ] = [xxad xxb ] h1: [ uu k i =1 xai d xbi ] = uu k i =1 h1i tab. 3 p-values table provided by npc test analysis. bold characters indicate values which are lower than the adopted significance α-level (0.05). tabella dei p-values ottenuta con l’analisi npc test. i numeri in grassetto indicano il valore di significatività inferiore allo 0,05. a. miola et al. uu uu 25 aacckknnoowwlleeddggeemmeennttss we would like to thank the anonymous referees for their comments and useful suggestions on a previous draft. rreeffeerreenncceess aa. vv. (1999) atti del convegno “le pianure. conoscenza e salvaguardia. il contributo delle scienze della terra”. ferrara, 8-11 novembre, 1999. accorsi c. a., bandini mazzanti m. & forlani l. (1984) spettri pollinici tardopleistocenici in sedimenti di pozzi nella pianura veronese. mem. mus. civ. st. nat. verona (ii serie), sez. sc. terra, 2, p. 35-63. accorsi c. a., bandini mazzanti m., forlani l., meneghel m., rigoni a. & sorbini l. (1989) primi dati stratigrafici e palinologici sulla sequenza di bernascone (verona), datata alla base 18.870± 300 b.p. infor. bot. ital., 21, p. 240-245. bertolani marchetti d. (1967) vicende climatiche e floristiche dell’ultimo glaciale e del postglaciale in sedimenti della laguna veneta. mem. biogeograf. adriatica, 7, p. 193-225. bondesan a., meneghel m., miola a. & valentini g. (2003) pollen analyses of lagoon and fluvial sediments of a 20 m core in the lower coastal river piave plain. palaeoenvironmental reconstruction from lgm to present. il quaternario, 16, no. 1bis, p. 183-192. bondesan a., mozzi p. & calderoni g. (2002) l’assetto geomorfologico della pianura veneta centro-orientale, stato delle conoscenze e nuovi dati. scritti in ricordo di giovanna brunetta, dip. geografia dell’università di padova, p. 19-38. bortolami g. c., fontes j., markgraf v. & saliege j. f. (1977) land, sea and climate in the northern adriatic region during late pleistocene and holocene. palaeogeography, palaeoclimatology, palaeoecology, 21, p. 139-156. calderoni g., castiglioni g. b., foddai d., gallio s., hinterwipflinger v., lombardo m., miola a. & zangheri p. (1996) palaeoenvironmental features of a perieuganean (padua, n italy) depression during the late quaternary, first results . il quaternario, 9, no. 2, p. 667-670. castiglioni g. b., girardi a. & rodolfi g. (1987) le tracce degli antichi percorsi del brenta per montà e arcella nei pressi di padova, studio geomorfologico. mem. scienze geologiche, 39, p. 129-149. castiglioni g. b. & pellegrini g. b. (eds.) (2001) note illustrative della carta geomorfologica della pianura padana. geogr. fis. dinam. quat. suppl. iv, 208 pp. goodwin h. (1981) the archives of the peat bogs. cambridge university press, cambridge, 229 pp. iliceto v., meloni f., mozzi p. & rizzetto f. (2001) il sottosuolo della cappella degli scrovegni a padova. geologia tecnica e ambientale, 4, p. 3-17. lezziero a. (1999) il sottosuolo di venezia, sedimentologia e paleoambienti. in: a.a. v.v., atti del convegno “le pianure. conoscenza e salvaguardia. il contributo delle scienze della terra”. ferrara, 8-11 novembre, 1999, p. 195-197. marocco r. (1989) evoluzione quaternaria della laguna di marano (friuli-venezia giulia). il quaternario, 2, no. 2, p. 125-137. miola a. & gallio s. (1997) primi dati palinologici sulla sequenza di galzignano del pleistocene superiore colli euganei (padova nord italia). in: accorsi c. a., bandini mazzanti m., labate d., trevisan grandi g. (eds.), “giornata di studi in ricordo di daria bertolani marchetti” (formigine, 18-5-96). deput. storia e patria. aedes muratoriana, modena, p. 415-420. mullenders w., favero v., ciremans m. & dirickx m. (1996) analyses polliniques de sondages a venise (ve-i, ve-i bis, ve-ii). in: gullentips f. (ed.) “pleistocene palynostratigraphy”, aardk. mededel., 7, p. 87-117. paganelli a. (1996a) a palynological study of forest vegetation in the veneto po plain. allionia, 34, p. 189-217. paganelli a. (1996b) evolution of vegetation and climate in the veneto po plain during the late-glacial and the early holocene using pollen–stratigraphic data. il quaternario, 9, no. 2, p. 581-590. paganelli a., miola a. & todaro a. (1988) ricerche palinologiche nel basso veneto. 1. biostratigrafia palinologica e dati radiometrici di alcuni depositi fluvio-lacustri. athesia, 2, p. 105-122. pesarin f. (2001) multivariate permutation tests with applications in biostatistics. wiley, chichester, 432 pp. pesarin f. (2002) extending conditional inferences to unconditional ones. journal of the italian statistical society, (in press). rizzi longo l. (1996) palynological evidence of the forest vegetation of the friuli plain, allionia, 34, p. 287-295. serandrei barbero r., lezziero a., albani a. & zoppi u. (2001) depositi tardo-pleistocenici ed olocenici nel sottosuolo veneziano, paleoambienti e cronologia. il quaternario, 14, no. 1, p. 9-22. ms. ricevuto il 6 novembre 2002 testo definitivo ricevuto il 25 marzo 2003 ms. received: november 6, 2002 final text received: march 25, 2003 pollen data for a biostratigraphy ... impaginato amato robustelli tthhee nnoocceellllaa ccoonngglloommeerraatteess:: aa pprroobblleemmaattiicc oouuttccrroopp hhiigghhllyy ssuussppeennddeedd oonn tthhee ssoouutthheerrnn ssllooppee ooff tthhee eeaasstteerrnn ssoorrrreennttoo ppeenniinnssuullaa ((iittaallyy)) aa.. aammaattoo11 && gg.. rroobbuusstteellllii22 1 dip. to di scienze della terra, università degli studi di napoli “federico ii”; amatoa@unina.it 2 dip. to di scienze della terra, università degli studi della calabria; robustelli@unical.it abstract a 130m thick sedimentary alluvial to slope deposits (nocella formation) rests on a concave up spur suspended between 660m and 800m on the southern coastal slope of the sorrento peninsula have been analized. stratified slope waste deposits (nocella breccias) unconformably and abruptly rest on nocella alluvial deposits (nocella conglomerates). facies analysis of the nocella conglomerates indicate a high-energy, gravel bed braided environment. in particular two facies association have been distinguished. the first one is representative of in-channel deposition and both vertical accretion and lateral and downstream migration of gravel bars. the second one reflect vertical accretion and downstream migration of low-relief gravel bars and extensive, locally in-channel, deposition by highenergy flood flows respectively. paleocurrent data indicate a wnw-sloping paleoslope away from a, nowadays, lacking highland. techniques of lateral profile analysis and hierarchical ordering of bounding surfaces has also been applied to the nocella conglomerates, and allows two different river model to be outlined. slope deposits also taper upslope coating a triangular facet belonging to the first fault scarp generation which occurred after the formation of the i order palaeosurface sailed by nocella conglomerates; they are cut by the second fault scarp generation together with relics of the ii order palaeosurface such as the agerola karst basin and the s.maria del castello erosional surface. we correlate the nocella alluvial deposits with the s. maria del castello relic of ii order palaeosurface and thus we propose a reconstruction of a part of the sorrento peninsula early pleistocene landscape. the source area of the nocella conglomerates should be a mountainous area located east-southeastward of nocella site and should be the same as, on the opposite side, fed the clastic infilling of the agerola karstic basin. riassunto sul versante meridionale della penisola sorrentina, in corrispondenza di uno sperone sospeso tra 660m e 800m s.l.m., affiora una successione sedimentaria spessa circa 130 m costituita da depositi alluvionali su cui poggiano depositi di versante. i depositi di versante (brecce di nocella) giacciono in discordanza sui depositi alluvionali (conglomerati di nocella). l’analisi di facies sulla porzione alluvionale della successione è indicativa di un ambiente fluviale ad alta energia di tipo braided. in particolare sono state distinte due associazioni di facies la cui differenza principale risiede nella maggiore o minore presenza di unità canalizzate, oltre alle loro geometrie, e nei caratteri geometrici delle forme migranti (barre). la direzione misurata delle paleocorrenti, che è wnw, evidenzia un chiara discordanza oroidrografica, in quanto l’attuale paesaggio manca completamente dei rilievi alimentatori. nell’ambito delle porzione alluvionale della successione affiorante sono state applicate tecniche di analisi laterale dei depositi e di ordine gerarchico delle superfici che limitano i principali elementi architettonici individuati al fine di caratterizzare la tipologia di modello fluviale. i depositi di versante mantellano versanti a faccette triangolari derivanti dal modellamento della scarpata di faglia di prima generazione che ha smembrato e dislocato il i ordine di paleosuperfici ed è stata fossilizzata dai conglomerati di nocella. essi sono dislocati da una ulteriore fase tettonica insieme ai relitti del ii ordine di paleosuperfici, correlabili con quelli che bordano la conca carsica di agerola e con la paleosuperficie di santa maria del castello. considerazioni di carattere morfostratigrafico ci hanno consentito di correlare i conglomerati di nocella con il relitto di ii ordine di peleosuperfici di santa maria del castello, e pertanto proponiamo una ricostruzione del paleopaesaggio che caratterizzava questo settore della penisola sorrentina durante il pleistocene inferiore. tale paleopaesaggio, che prevede la presenza di una area montuosa sorgente dei conglomerati di nocella a ese della successione analizzata, probabilmente fungeva da area sorgente anche per i depositi che costituiscono il riempimento clastico della conca di agerola. keywords: palaeosurfaces, fluvial deposits, facies analysis, sorrento peninsula, early pleistocene. parole chiave: paleosuperfici, depositi fluviali, analisi di facies, penisola sorrentina, pleistocene inferiore. il quaternario italian journal of quaternary sciences 1155(1), 2002, 83-96 11.. iinnttrroodduuccttiioonn the sorrento peninsula is an ene-wsw trending morphostructural high interposed between the perytyrrhenian depressions (grabens) of the gulf of naples-campana plain to the north, and the gulf of salerno-sele plain to the south (fig.1). it consists mainly of a mesozoic carbonate units (the picentini mts.-mt. taburno tectonic unit; bonardi et al., 1988) and of a miocene terrigenous synorogenic units. due to its position (it is one of the westernmost outcropping part of the southern apennines chain) together with the conservativity of its lithologic units, the sorrento peninsula represents important evidence of the early phases of post orogenic morphostructural evolution of the southern apennine chain (cinque et al., 1993). as regards the structural setting of the sorrento peninsula, it represents a nw dipping monocline which is dislocated into minor blocks by two systems of high angle fault trending nw-se and ne-sw. in particular the anti-apenninic system is responsible for formation of the grabens of napoli and salerno (bartole et al., 1984; sacchi et al., 1994); an e-trending system fault has contributed to the development of the first one too. previous authors distinguished up to five block-faulting phases during plio-pleistocene time on the basis of structural data (torrente et al., 1999). by a morphostructural point of view, there are three main deformation phases 84 a. amato g. robustelli f ig . 1 g e o lo g ic a l s ke tc h m a p o f th e s o rr e n to p e n in su la ( fr o m c a ia zz o e t a l., 2 0 0 0 , m o d ifi e d ). t h e f ra m e d a re a c o rr e sp o n d s to t h e o n e r e p o rt e d in f ig . 2 . s ch e m a g e o lo g ic o d e lla p e n is o la s o rr e n tin a ( d a c a ia zz o e t a l., 2 0 0 0 , m o d ifi ca to ). l ’a re a n e l r iq u a d ro c o rr is p o n d e a q u e lla r a p p re se n ta ta in f ig . 2 . (caiazzo et al., 2000), which occurred during the early pliocene-late middle pleistocene time interval, in response to the eastward migration of the thyrrenian extensive domain (sartori, 1989, 1990). the presence of raised marine terraces indicates the uplift of the sorrento peninsula from the lower pleistocene to the middle pleistocene, during which the width of the peninsula was progressively reduced by block faulting that affected the southern flank enlarging the contiguous gulf of salerno (cinque, 1986). the emerged marine terraces along the southern slope of the sorrento peninsula allow cinque & romano (1990) to infer that the latest phases of block faulting occurred during the late middle pleistocene and that sorrento peninsula stopped rising no later than the last interglacial. on the contrary, the nearby campana-plain graben has continued to subside during the upper pleistocene to present time (milia, 1996). since no absolute chronological constraints have ever been reported, the different stages in which the morphostructural evolution of the sorrento peninsula have been divided are only relatively dated. the beginning of the geomorphologic history of the sorrento peninsula is as old as the formation of the i order palaeosurface, suspended up to 1300 m a.s.l. on the top of mt. faito (fig. 2), which has been ascribed to a probably early – middle pliocene time (caiazzo et al., 2000). the oldest geomorphological elements are few hanging relics remnants of mature erosion landscape (i order palaeosurface). after a phase of block faulting that disrupted and uplifted the i order palaeosurface, a new base-level established some hundreds of meters below. in this paper we attempt to reconstruct the landscape of this geomorphological stage, now broken and suspended up to 850 m a.s.l., by considering different types of evidences preserved in the studied area and by analysing the stratigraphic and sedimentological characteristics of the here informally named nocella formation. 22.. ggeeoommoorrpphhoollooggyy the sorrento peninsula is characterised by a clear structurally controlled landscape, as it is dominated by the occurrence of fault scarps and structural cliffs and valleys (figg. 1, 2). moreover, due to the vicinity of the sea, the area experienced a great number of eustatic controlled fluvial dissectional cycles, which actively contributed to reduce or even cancel the erosional landforms modelled during the pauses of the tectonic activity. nonetheless, clear traces of ancient erosional cycles occur and we attempt to interpret them in terms of palaeoenvironment and relative age. in the geomorphological map of fig. 2, the main structural, erosional, and depositional landforms of the eastern sorrento peninsula are reported, and the relative inferred ages are also proposed (see section 4 for discussion). two sectors have been distinguished: the eastern one, which is dominated by the high homoclinal calcareous block of mt. faito, and the western one, which is sensibly lower. the two sectors are separated by the fault scarp of mt. faito which transversally crosses the peninsula. on both the sectors we recognise relics of palaeosurfaces testifying the occurrence of past phases 85the nocella conglomerates ... of relief smoothing under the control of both local and general baselevels of erosion. most of the relics cut across dipping strata, but in some cases they rest on almost horizontal strata. in few cases (e.g., faito, agerola) they are associated to outcrops of undated continental conglomerate. more frequently, these surfaces lack any type of deposits, so that their chronology is uncertain. the only ancient (early pleistocene?) clastic deposits are the nocella alluvial deposits (see section 3) suspended between 700 and 775 m a.s.l., on a policyclic slope. more precisely, these deposits are cut by the free face of a coastal fault scarp whose slope is about 35%. above this free face the slope changes in about 25% and appears concave up to the summit where the top surface of mt. faito occurs. this change in slope gradient is due to a different lenght of the erosional processes which caused the decline and the slope replacement of the relative fault scarp planes. the more ancient erosional cycle is well represented by the highest relics of palaeosurface occurring on the eastern uplifted block, indicated on the map of fig. 2 as the i order palaeosurface. the relics of the i order palaeosurface are almost reduced to flat watershed, but locally (see the top of ridge that limits the agerola plain to the east) they include also wind gaps clearly unlinked to the modern valley network. as mentioned before, on the top of mt. faito these surfaces are associated with the outcrop of severely eroded clastic deposits, interpreted as slope and fan breccias, produced when the base level was very near to those of the i order palaosurface landscape. the mt faito palaeosurface could be upper pliocene in age, since it is younger than the miocene n-verging thrustsand older of the phase of normal block –faulting (probably late pliocene – early pleistocene (aucelli et al., 1996). the slope fault scarp of the sorrento peninsula can be divided in two main groups: a first characterized by concave up profiles with mean gradients of about 25 – 30 % , standing on the highest portions of reliefs, locally just behind the relics of the i order palaeosurface; the other ones is represented by the lower tracts of slopes, characterized by higher gradients (in the order of 40 % and more), convex profiles frequently disrupted by parallel fault planes. these two different types of slope profile are locally separated by relics of the ii order palaeosurface, that occur on both the eastern and the western sector. it is probable that part of the ii order relics, as well as some lower erosional terraces must be interpreted as downfaulted portions of the i order palaeosurface that were simply remoulded during the pause of the tectonic activity that allow the ii order palaosurface to be formed. different examples of this type are widespread on the western downfaulted sector of the study area. we will describe two cases: the surface of the agerola karst basin, and the s.maria del castello surface. the agerola graben was formed by the tectonic phase that disrupted the i order palaeosurface by the normal activity of the n-s trending faults on which the western slope of the sproviere murillo ridge and the eastern slope of mt. tre calli ridge are sculptured. the top surface of the graben can be considered a ii order surface, it is a policyclic surface suspended at about 86 a. amato g. robustelli f ig . 2 g e o m o rp h o lo g ic a l sc h e m e o f th e s o u th e a st e rn s o rr e n to p e n in su la : 1 ) va lle y d o w n cu tt in g ; 2 ) h a n g in g v a lle ys a n d w in g g a p s; 3 ) st ru ct u ra l sl o p e ; 4 ) m id d le p le is to ce n e f a u lt sc a rp ; 5 ) e a rl y p le is to ce n e f a u lt sc a rp ; 6 ) m id d le – u p p e r p le is to ce n e 3 rd o rd e r p a la e o su rf a ce ; 7 ) e a rl y p le is to ce n e 2 n d o rd e r p a la e o su rf a ce ; 8 ) e a rl y p lio ce n e 1 st o rd e r p a la e o su rf a ce . s ch e m a g e o m o rf o lo g ic o d e l s e tt o re s u d – o ri e n ta le d e lla p e n is o la s o rr e n tin a . 1 ) in ci si o n i v a lli ve ; 2 ) va lli s o sp e se e v a lli r e lit te ; 3 ) ve rs a n te s tr u tt u ra le ; 4 ) sc a rp a ta d i f a g lia m e d io p le is to ce n ic a ; 5 ) sc a rp a ta d i fa g lia i n fr a p le is to ce n ic a ; 6 ) p a le o su p e rf ic ie d i 3 ° o rd in e ( p le is to ce n e m e d io – s u p e ri o re ); 7 ) p a le o su p e rf ic ie d i 2 ° o rd in e ( p le is to ce n e i n fe ri o re ); p a le o su p e rf ic ie d i 1 ° o rd in e (p lio ce n e in fe ri o re ). 87the nocella conglomerates ... 650 m a.s.l. the graben infilling outcrop of few tens of meters in river incision and consists of a polygenic angular conglomerate composed of carbonatic and subordinate terrigenous clasts, the latter derived from a miocene terrigenous unit outcropping during early pleistocene time and then tectonically drowned under the sea of the salerno gulf. due to the bad exposition, a more precise facies interpretation and source direction are not available for these deposits, except for those outcropping along the rim of the graben, which are at the top of the clastic infilling body and can be interpreted as slope breccias deposits. we don’t have enough elements to establish if the endoreic conditions date back to the birth of the graben or if they developed after, but surely they had a long duration as demonstrated by signs of remarkable karstic planation along the borders of the basin, suspended at about 630 and 570 m a.s.l.. the epikarstic activity was interrupted by the tectonic phase that downfaulted the southern rim of the agerola intramontane endoreic basin and promoted its capture by the retrogressive deepening of the schiato stream gorge. the s. maria del castello surface is located on the western sector, it is an erosional landsurface suspended upon positano town at about 650 m a.s.l. with the shape of a low gradient wide valley tract nw dipping. it is truncated by a fault scarp ne-sw oriented and dipping to the north, whose characteristics are those typical of the second, more recent type of slopes. toward the ne the s. maria del castello ii order surface confine with the base of the punta medico slope, which is one of the triangular relics of the first type fault scarps formed by slope replacement and then deeply dissected. near s. maria del castello, entrenched within the ii order palaeosurface are other terraced alluvial fan conglomerates, suspended between 500 and 550 m a.s.l. (moiano conglomerates). similar deposits occur near pimonte, on the northeastern side of mt. faito. both moiano and pimonte conglomerates are suspended and hence older than the other dissected alluvial fan occurring at lower elevations and located in the lower tracts of the valleys. these younger alluvial fans are middle and late pleistocene in age. similarly, the traces of marine terraces suspended between 6-8 m and 50 m a.s.l. on the southern coast are late pleistocene to middle pleistocene in age (cinque & romano, 1990). on the basis of the existing knowledge, the moiano and pimonte conglomerates can be referred to a generic middle pleistocene. 33.. nnoocceellllaa ffoorrmmaattiioonn the nocella formation. lies with pronounced angular unconformity upon jurassic dolomitic limestones, which constitute the bulk of the relief. the best exposed stratigraphic section , about 130m thick, outcrops on a hanging, concave up spur ranging between 660m and 800m in elevation (fig. 3). here stratified slope waste deposits (nocella breccias) rest unconformably on nocella alluvial deposits (nocella conglomerates) proofing that their deposition occurred soon after the alluvial one. slope deposits tend to taper upslope coating a triangular facet which is one of the triangular relics of the scrajo-vettica fault scarp on fig. 3 overview photograph of the studied section. the location of the logs are marked and numbered. the nocella formation, resting uncomformably above jurassic limestones, consists of alluvial deposits (nocella conglomerates) overlaid by slope breccias (nocella breccias). the northern segment of the scrajo-vettica fault is also marked. panoramica dell’area studiata. s1 ed s2 indicano le sezioni esaminate. la formazione di nocella, discordante sui calcari giurassici, è costituita da una porzione inferiore alluvionale (conglomerati di nocella) passanti verso l’alto a brecce di versante (brecce di nocella). in figura è inoltre segnalata la traccia del segmento settentrionale della faglia scrajo-vettica. 88 a. amato g. robustelli which the south-eastern slope of the mt. tre calli ridge are sculptured by slope replacement processes coupled with consequent river dissection. the basal angular unconformity represent an asymmetric paleovalley into which nocella conglomerates were deposited and, in particular, sail the north-eastern segment of the scrajovettica fault zone. steep and high scarp perimeters the spur at issue which reflects the re-activation of the the scrajo – vettica fault zone and its dissection by consequent incisions characterised by steep flanked v-shaped valleys having high longitudinal gradients. their longitudinal cross-profile is characterized by upper reach steeper than the slope they dissect. the nocella conglomerates, about 90m thick, has been chosen as a type section for detailed description of the sedimentary facies. as the vertical cliff which confines the spur does not allow a complete sedimentary log to be given, only the middle and the upper portion of the nocella conglomerates have been analysed in detail (fig. 3); they outcrop on the north-western and southeastern part of the spur respectively. minor exposures of clastic deposits belonging to the same morphoevolutive stage occur close to hanging, concave-up footslope of the scrajo-vettica fault zone. the nocella type section consists of a crudely cu sequence characterized by the dominance of conglomerate lithofacies (>95%) with very subordinate sandstone lithofacies. fine grained lithofacies were not observed. conglomerate lithofacies are clast supported, poorly to moderately sorted, and contain angular to subrounded clasts. clast size is generally in the pebble to cobble range although boulders up to 30 cm occur in the topmost part of the sequence. the lithology does not vary over the study area; dominant clasts include white to greyish dolomitic limestone mainly of jurassic age (coming from the jurassic part of the local mesozoic succession). rare clasts of miocene flysch deposits also occur, suggesting that miocene terrigenous deposits outcropped in the source area of nocella conglomerates. 33..11 lliitthhooffaacciieess ddeessccrriippttiioonn the nocella conglomerates is characterized by six sedimentary facies distinguished on the basis of sedimentary structures and bed geometry. paleocurrent data indicate wnw-ward paleoflows close parallel to the scrajo-vettica fault zone. two sedimentary logs are given in fig. 4; they are representative of the middle and the upper part of the nocella conglomerates and are located respectively along the nw and se side of the spur (figg. 3 and 4). table 1 summarizes the lithofacies codes used in describing nocella conglomerates, based on the fluvial lithofacies code modified from miall (1996). lliitthhooffaacciieess ggccmm –– ssttrruuccttuurreelleessss,, ccllaasstt--ssuuppppoorrtteedd ccoonn-gglloommeerraattee this facies consists of pebble to cobble-size clasts subangular in shape; they are moderately to poorly sorted and display a clast-supported texture (fig. 5). matrix content is generally less than 20% and consists of coarse sand and granules. conglomerate fabric is disorganized, although it appears locally to be a preferred clast orientation. the longest a-axes of some elongate clasts are parallel to paleoflow directions; locally a(p)a(i) fabric fig. 4 logs of the nocella conglomerates along the northwestern (s1 in fig. 2) and south-eastern (s2 in fig. 2) side of the nocella spur (fig. 2). letters refer to lithofacies and arrows indicate paleocurrent. the paleocurrent rose refers to the total number of measurements. sezioni stratigrafico-sedimentologiche dei conglomerati di nocella sul lato nord-occidentale (s1 in fig. 2) e sud-orientale (s2 in fig. 2) dello sperone visibile in fig. 2. le sigle si riferiscono alle litofacies mentre le frecce indicano la direzione delle paleocorrenti. il diagramma si riferisce al totale delle misure effettuate. mode occur. grading is absent or basal inverse grading and crudely normal grading locally occur. the conglomerates consist of lenticular or laterally apparently continuous, non erosive-based units whose thickness range between 10 to 45cm. this lithofacies occurs mostly in the upper part of nocella conglomerates and is interbedded with gci and gh lithofacies lliitthhooffaacciieess ggccii –– iinnvveerrsseellyy ggrraaddeedd,, ccllaasstt--ssuuppppoorrtteedd ccoonn-gglloommeerraattee this facies consists of pebble-size clast, although cobbles up to 20 cm locally occur. the clasts are angular to subrounded; they are moderately sorted and characterised by a clast-supported texture, with a coarse sand matrix locally absent. inverse grading is well developed and a(t)b(i) fabric mode is locally present. beds of this facies have sharp non erosional lower contacts and occur in lenticular units that are up to 30 cm thick and up to 8m wide; locally such lenticular beds show a convex-top boundary. as for gcm facies, this lithofacies has been well recognized in the upper part of nocella conglomerates. lliitthhooffaacciieess gghh –– hhoorriizzoonnttaallllyy ssttrraattiiffiieedd ccllaasstt--ssuuppppoorrtteedd ccoonngglloommeerraattee pebble to fine cobble-size clasts in this facies are subangular to subrounded; they are moderately to well sorted with a clast-supported texture (fig. 5). well developed bedding and horizontal stratification is ubiquitous; 89the nocella conglomerates ... pebble-size clasts show a local well developed a(t)b(i) fabric mode. imbrication and cluster bedforms indicate paleoflow directions toward wnw. conglomerate beds are usually normal graded (fig. 5); medium to coarse sand matrix is usually present but open framework conglomerate beds also occur (fig. 5). local beds exhibit bimodality both (fig. 5) in the lower and in the upper band of each bed textural inversion of nemec & steel (1984) and steel & thompson (1983). these conglomerates occur in laterally continuous beds that can be traced for at least 20m; basal contacts are usually sharp and planar, but local scour surfaces may be observed. these sheet-like units, tipically few dm thick (up to 40cm), set up multistory units up to about 4m thick. this lithofacies is interbedded with gcm and gci lithofacies, but is well developed also in the middle part of the nocella conglomerates. lliitthhooffaacciieess ggpp –– ppllaannaarr ccrroossss--bbeeddddeedd ccllaasstt--ssuuppppoorrtteedd ccoonngglloommeerraattee this facies consists of subangular to subrounded pebbles. the clasts are moderately to well sorted and characterised by a clast-supported texture. well developed planar cross-stratification occurs; the foreset beds, up to 15cm thick, consist of alternating fine and coarse pebbles without any signs of rhythmic organization. dip azimuth of the foreset beds is toward sse; dip angle range from few degrees up to 13°. foreset beds appear to be ungraded. sandy matrix is scarce but usually present; some local foreset beds have an open framework. these conglomerates occur in laterally continuous tabular units, ranging from 50 to 110cm in thickness, with internal scour surfaces. basal contacts are sharp and non erosive; top contact shows a local convex-up boundary (fig.6). this lithofacies occurs in the middle part of the nocelle conglomerates and grade laterally into gh lithofacies. lliitthhooffaacciieess ggtt aanndd ggtt11 –– ttrroouugghh ccrroossss--ssttrraattiiffiieedd ccoonngglloo-mmeerraattee trough cross-stratified conglomerate occur as single sets ranging from 0.6m to 1,5m deep and from 1,2m to 7.4m in width. basal scours affect both the conglomerate facies and sandy ones; channel margins are gentler in slope with increasing channel width the bigger ones occur in the middle part of the nocella conglomerates (fig. 7a). this facies is developed in pebble size clasts, subangular to subrounded; they are moderately to well sorted with a clast-supported texture. fig. 5 set of clast-supported conglomerates with disorganized fabric (gcm facies) overlay normal graded, horizontally stratified conglomerates (facies gh). note also the poor degree of rounding of the clasts. paleoflow is obliquely into the face and to the left. strati di conglomerati massivi, clasto-sostenuti (facies gcm) ricoprono conglomerati stratificati organizzati in unità normalmente gradate (facies gh). si può notare lo scarso grado di arrotondamento dei clasti. i paleoflussi sono obliqui e diretti verso sinistra. facies facies sedimentary intepretation code structures gcm massive, clast none or weak pseudoplastic cohesionless supported gravel grading debris flow or high sedimentconcentration flood flows gci clast-supported inverse grading, clast-rich debris flow or gravel locally imbrication hyperconcentrated flood-flows; filling of broad, sheet-like channels gh clast-supported, horizontal bedding, accreditionary units longitudinal well bedded gravel imbrication bars gt gravel, stratified trough cross-beds minor channel fills gt1 gravel, stratified low-angle and/or rapid scour fills by highhorizontal bedding concentration flood-flows gp gravel, stratified planar cross-beds transverse accretion units of bars sh coarse sand, many crude horizontal deposition from heavily be pebbly lamination, locally sediment-laden flows during massive waning floods above bars table 1 description and interpretation of sedimentary facies adapted from bridge (1993) and miall (1996) trough fill consists of non rhythmic alternating fining upward and ungraded low angle sets (gt lithofacies fig.7a); their thickness is up to 15cm and they dip of about 10°. locally lag deposits of coarser grain size (up to fine boulders) grading upward into gci lithofacies occur above a bowl-shaped, erosional bases of trough sets (gt1 lithofacies; fig. 7b). through fill consists also of stacked sets of gh lithofacies. just once (fig. 7c) well developed foreset beds dipping north-westward was observed overlying gt1 lithofacies; these beds may be considered as gp lithofacies and grade upward into gh lithofacies. lliitthhooffaacciieess sshh –– hhoorriizzoonnttaallllyy ssttrraattiiffiieedd ssaannddssttoonnee this lithofacies consists of sand to granule size clasts, with a local occurrence of isolated out-sized clasts (a-axes>5cm). it is organized in lenses and/or wedge-shaped units locally up to 15cm thick and over 7m extended. locally they show crude horizontal stratification. massive texture was also observed. sandy facies usually rest on gh lithofacies. 33..22 ffaacciieess aassssoocciiaattiioonnss iinntteerrpprreettaattiioonn lateral and vertical facies associations, paleocurrent and coarse-grained texture suggest that the nocella conglomerates was deposited in a high velocity stream. on the basis of comparisons with the degree of rounding shown by other pleistocene alluvial units of the 90 a. amato g. robustelli fig. 6 middle part of the nocella conglomerates: one largescale sets of planar cross-stratified conglomerates (gp facies) overlain and underlain by horizontally stratified conglomerates (gh facies). porzione intermedia dei conglomerati di nocella: si nota un intervallo a stratificazione incrociata-planare (facies gp) intercalato in conglomerati a stratificazione orizzontale (facies gh). fig. 7 trough cross-stratified conglomerates: a – example of large-scale gt facies cut into gh ones near the middle of the nocella conglomerates. b – oblique view of trough cross-stratified conglomerates (gt1 facies), underlying horizontally stratified conglomerates (gh facies). c – oblique view of trough cross-stratified conglomerates (gt1 facies), showing coarse lag above scour surface; trough fill consists of alternating fine and coarse pebble foresets (gp facies) characterized by a decrease of dip angle with a gradual transition into gh facies. .conglomerati organizzati in unità canalizzate: a – esempio di unità canalizzata (facies gt) che incide conglomerati a stratificazione orizzontale (facies gh) nella porzione intermedia dei conglomerati di nocella. b – vista obliqua di conglomerati organizzati in unità canalizzate (facies gt1), cui seguono in successione conglomerati a stratificazione orizzontale (facies gh). c – vista oblique di conglomerati organizzati in unità canalizzate (facies gt1), in cui si osservano i depositi residuali basali poggianti sulla superficie di erosione; il riempimento è costituito da un’alternanza di ghiaie fini e grossolane a stratificazione incrociata-planare (facies gp) e di cui gli strati sono caratterizzati da una riduzione della pendenza e da un graduale passaggio alla facies gh. area, we can estimate that the river reach upstream of nocella outcrop, i.e. the feeding stream, was at least a 2-3 kilometres long. two facies associations have been distinguished, and their depositional systems have been reconstructed accordingly as follows: ffaacciieess aassssoocciiaattiioonn 11 is restricted to the middle portion of the nocella conglomerates. horizontally stratified conglomerates (gh lithofacies) is the most common facies typically forming sheet-like units. subordinate lithofacies are represented by planar crossstratified conglomerates (gp lithofacies). minor lithofacies consist of trough cross-stratified conglomerates (gt lithofacies) and horizontally stratified sandstones (sh lithofacies). contacts between gh and gp lithofacies are usually sharp and flat, but locally they are slightly scoured. these conglomeratic lithofacies occur in laterally continuous tabular beds that can be traced for several meters. the dominance of horizontally stratified conglomerates with local internal scour indicates that high-energy tractional processes were involved, as the coarse-grained texture and the absence of fines also suggest. in particular, the dominance of tabular conglomerate sheets indicates that deposition was laterally extensive; although the occurrence of broad and shallow channels is shown by internal erosive surfaces. as a whole this facies is interpreted as being formed by deposition and migration of bars in a highenergy gravel-bed river (miall, 1977; rust, 1978; collinson, 1986; miall,1996). evidence for stream flow processes includes also clast-supported framework, a(t)b(i) fabric mode and lenticular trough cross-stratified conglomerates, the latter occur as minor lithofacies. the channellike bedforms consist of few local scours over 1m deep and 5m wide. the cross-cut relationship with gh lithofacies suggest that trough-cross stratified conglomerates may be representative of channels cutting across bars top and/or front during falling water, followed by gradual infilling of the scours. the southern tip of the western measured section represent the one and only place at which the continuity of exposure allows us to attempt a hierarchical classification of the depositional units and bounding surfaces. however, even there the impossibility to look frontally at the whole exposure prevents us from getting reliable results. nevertheless, it is noteworthy that horizontally stratified conglomerate grade laterally into gently inclined gp lithofacies (fig. 8; tab. 2), which can be interpreted as lateral accretion of gravel sheets on inclined surfaces, indicating a margin of a macroform (tab.2; element la sensu miall, 1985; 1988). the overlying and underlying horizontally stratified conglomerate have been interpreted as indicative of element gb of miall (1985, 1988). therefore the presence of element gb (tab.2) and the occurrence of locally interbedded element la (tab.2) may be interpreted, according to miall (1996), as representative of a shallow to relatively deep, gravel-bed braided river. an architectural model of this type of river may be considered the model 3 of miall (1985) ffaacciieess aassssoocciiaattiioonn 22 is restricted to the upper portion of the nocella conglomerates. the most common facies is the horizontally stratified conglomerates (gh), typically forming sheet-like units. subordinate lithofacies 91the nocella conglomerates ... fig. 8 – oblique view (a) and interpretation of the photograph (b). for element and facies codes see tables 1 and 2. circled numbers refer to the order of bounding surface. circled letters are architectural elements. for element and facies codes see tables 1 and 2. vista obliqua (a) ed interpretazione (b) di una porzione della sezione s1. per le sigle delle facies e degli elementi architettonici vedi le tabelle 1 e 2. i numeri si riferiscono all’ordine gerarchico delle superfici che limitano gli elementi architettonici (lettere cerchiate). le sigle delle facies e degli elementi architettonici sono indicate rispettivamente in tabella 1 and 2. are represented by massive conglomerates (gcm lithofacies) and inversely graded conglomerates (gci lithocacies). minor lithofacies consist of trough cross-stratified conglomerates (gt and gt1 lithofacies) and horizzontally stratified sandstones (sh lithofacies). gp lithofacies was not observed. this association is characterized by stackedsheets of graded and massive clast-supported conglomerates. the sheet-like beds range from few centimeters up to 50 cm in thickness and can be traced over a distance of several meters (see fig. 3, upper part of nocella conglomerates). the bases of the conglomerate sheet.-like bedforms are sharp and flat, but scour surfaces occur so lenticular units may be recognized. as for the facies association 1, the dominance of horizontally stratified conglomerates suggests that high-energy traction-current processes were the main depositional processes. therefore this facies is interpreted as being formed by migration of shallow and broad braided channels with abundant low-relief bars in high-energy gravelbed river. the lack of evidence of planar cross-beds (gp lithofacies), whose origin requires deep-water channel (bluck, 1979; steel & thompson, 1983; kraus, 1984), provides evidence of the shallow depth of the paleochannels. clast-supported framework, a(t)b(i) fabric mode and cluster bedforms are further evidences for stream flow processes. the massive (gcm) and inversely graded (gci) lithofacies suggest that depositional events were occasionally of very high energy; in particular, according to shultz (1984) gcm and gci lithofacies can be considered as depositional evidences of pseudoplastic debris flow and clast-rich debris flow respectively; as also suggested by lowe (1982), gloppen & steel (1981) and nemec & steel (1984), or representative of very high sediment-concentration dispersions (dilution of debris flows) such as hyperconcentrated flood-flows (pierson, 1980; pierson & scott, 1985; ridgway & decelles, 1993; scott, 1988; smith, 1986; smith & lowe, 1991; waresback & turbeville, 1990). todd (1989) suggests a stream driven origin (high-density gravelly traction carpets) for the gcm and gci lithofacies; in particular gci lithofacies is representative of granular flows in which during motion a dispersive pressure dominates (lowe, 1982; sohn et al., 1999; todd, 1989). the massive, structureless conglomerates represent the deposits of cohesionless debris-flow (smith & lowe, 1991; sohn et al., 1999) dominated by frictional grain interactions in which clast collision is hampered resulting in the lack of inverse grading and clast imbrication. the lenticular trough cross-stratified conglomerates consist of few local bowl-like channels less than 1m deep and 5m wide. the local infillings consists of inchannel deposition by high-magnitude flood-flows (gt1 lithofacies, figg.7b and 7c; hein & walker, 1977; miall, 1977; nemec & postma, 1993; jo & chough, 2001); in particular gp lithofacies (fig. 7c) may be interpreted as cross-bedded conglomerates developing where channels debouche into pools (ramos & sopena, 1983). as a whole we may interpret the laterally extensive conglomerate sheets as elements gb (sensu miall, 1985; 1988; tab. 2) in which high energy flood-flow deposits (gcm and gci lithofacies) are subordinate and representative of broad, low-relief channel fill. element gb consists of three types of gravel tractions-current deposits; gh lithofacies predominates, whereas tha gt and gt1 ones are very subordinate. the interbedded lenses of horizontally stratified sandstones (sh lithofacies) may represent remnants of element sb due to rapid deposition from heavily sediment-laden flows 92 a. amato g. robustelli element and symbol horizontally stratified sets (gb) l a r g e s c a l e , planar crossstratified set (la) channel (ch) s m a l l s c a l e scour fill (ch1) principal facies assemblage gh, gcm and gci interbedded gp, gh any conbination gt, gt1, gp and gh bounding surfaces bound by erosively and accretionary fourth-order surfaces, planar to convex-up bound by fourthorder surfaces and internal third -order surfaces between accretion elements bound with concave-up, fifthorder surfaces provide palaeocurrent of downstream accretion directions. associated with concave-up, fourthorder surfaces description stacked sets of horizontally stratified conglomerates; individual sets, decimeters thick and meters (up to 20 m) in lateral extent, parallel strata. solitary set of planar crossstratified conglomerates dipping about perpendicular to paleocurrent direction; decimeters thick and meters in lateral extent. lenticular unit with concaveup, erosional base; up to 5m thick and tens of meters wide. lenticular unit with concaveup, erosional base; solitary unit, decimeters to 1,2m thick and meters wide. interpretation vertical aggradation and downstream migration of broad, lowrelief bars. filling of broad, sheet-like channels by deposition from highly concentrated flows lateral accretion of bars with internal re-activation surfaces filling of major channels filling of minor channels and scours on bars table 2 description and interpretation of architectural elements adapted from miall (1985, 1988, 1996) and bridge (1993) 93the nocella conglomerates ... during waning flood (todd, 1989; maizels, 1993; jo & chough, 2001). this kind of facies architecture, according to miall (1996), is consistent with a shallow, gravel-bed braided river interpretation. the architectural model of this type of river could be the model 2 of miall (1985). 44.. ddiissccuussssiioonn the sedimentologic and geomorphologic data reported above allows us to propose a new and more complete interpretation of the highly hanging clastic deposits outcropping near to nocella village, previously interpreted as slope replacement breccia by brancaccio et al. (1979) and cinque (1986). the detailed facies analyses of the nocella conglomerates have documented an high-energy, gravel-bed fluvial setting with a wnw-sloping paleoslope, the latter suggested by paleocurrent data. facies association 1, although characterized by a dominance of horizontally stratified conglomerates (gh lithofacies), consists also of laterally extended sets of planar cross-stratified conglomerates (gp lithofacies) that grade laterally into the gh one (lateral accretion of gravel bars on inclined surfaces; element la sensu miall, 1985; 1988). facies association 2 is characterized by gh lithofacies with subordinate gcm and gci ones, and a lack of planar cross-stratified conglomerates. the dominance of laterally extensive gravelly sheets coupled with the absence of gp lithofacies suggests that flow depths were more shallow than ones suggested by facies association 1. on the basis of comparisons with the sedimentological features offered by the pleistocene alluvial fan deposits of the pimonte area (aucelli et al., 1996), a confined alluvial fan interpretation may be proposed as the nocella conglomerates consists mainly of stackedsheets of graded and massive clast-supported conglomerate, which can be traced over a distance of several meters; in fact the gathered data are indicative of deposition and migration of low-relief longitudinal bars in shallow, high-velocity gravel-bed stream. but the lack of other outcrops beside that of nocella does not enable us to definitely confirm this hypothesis as an abrupt basinward facies transition may not be observed. although a vertical change from more distal to proximal fluvial settings is suggested by both the disappearing of macroforms interpreted as laterally accretion of gravelbars and the upward abrupt increase of high energy flow deposits (gcm and gci lithofacies). in order to interpret the vertical change of the facies associations within the nocella succession, different factors can be considered. first of all the angular to subrounded shape of the nocella conglomerates clasts prove that slope deposits produced by paipo fault scarp retreat are poorly reworked by fluvial processes as the absence of slope deposits interfingering with fluvial ones suggest. a climatic factor could also be considered to unravel the varying vertical facies association of the nocella conglomerates: the river models deduced by analysing the facies architecture may witness a decrease of water discharge and/or an increase of sediment supply. the abrupt transition from fluvial deposits to slope ones should be due to early – middle pleistocene re-activation of the southern segment of the scrajovettica fault zone which could have beheaded the upper reach of the catchment. conversely, the same abrupt transition could also be due either to a sudden lateral (south-westward) shifting of the watercourse or to the advancing of the debris slope after a phase of downcutting. moving north-westward suspended at about 600 – 650 m a.s.l. stand the s. maria del castello ii order relic (figg. 2 and 3) and a small erosional hanging terrace both sealing the scrajo – vettica fault. also the paipo breccias, located south-eastward of nocella site, seal the older segment of the scraio-vettica fault zone. these erosional and depositional landforms have been interpreted to belong to the same geomorphological stage, apart from the uppermost slope deposits which could also be more recent, in the case of a preceeding phase of downcutting or tectonic behading of the upper catchement. as a whole it was concluded that the paleomorphology of the study area, at the time of the nocella conglomerates deposition, was quite different from the modern one. the source area of the nocella conglomerates has to be related to a small river catchment nested into a nowadays lost morphostructural high located east-southeastward of the study area (fig. 2). this topographic high had to include also the mountainous area that fed the clastic infilling of the agerola karstic basin, whose western deposits show a clear dip towards northeast (brancaccio et al., 1976; cinque, 1986). moreover, the gentle landscape of s. maria del castello site settled at the footslope of the scraiovettica maggiore fault scarp, represents the wnw part of a low relief landscape, that we interpret as part of the wnw-sloping paleoslope of the river basin in which the nocella conglomerates were deposited. in order to better clarify the chronological frame of the ii order palaeosurface and its correlative deposits of nocella formation we summarize the whole geomorphological evolution of the sorrento peninsula. the oldest geomorphological stage is recorded by the formation of the i order palaeosurface (fig.9-i) there follows a phase of block-faulting driven by nesw direction of extension led to the fragmentation of this landscape, well documented by the structural analysis carried out on the scraio vettica fault (fig. 9-ii; caiazzo et al., 2000). after the early pleistocene activity, the ii order palaeosurface developed with a base–level ranging between 600 – 750 m a.s.l.(fig. 9iii). as reported by caiazzo et al., 2000 part of the scraio vettica fault zone was reactivated during early pleistocene – middle pleistocene p.p. and driven by nw-se direction of extension; the only southern segment coinciding with the present structural sea-cliff between positano and vettica towns moved during this more recent phase. after the early pleistocene – middle pleistocene p.p. tectonic phase, the relics of the ii order landscape were suspended, the nocella fm. and the paipo breccias were truncated, and, seemingly, whole portions of the ii order landscape (southern portions of the area) which had to represent the source area of these clastic units, were definitively drowned (fig. 9-iv). as a consequence, the age of the ii order palaelandscape should be early pleistocene. 55.. ccoonncclluussiioonn we have reconstructed the early pleistocene palaeolandscape of a portion of the eastern sorrento peninsula by detailed geomorphologic survey and sedimentological analysis of the nocella formation. on the basis of our data this hanging succession, previously interpreted as entirely composed of slope breccias, consists of a basal portion (about 90m thick) of alluvial deposits (nocella conglomerates), overlain by stratified slope deposits (nocella breccias). the nocella conglomerates can be referred to the geomorphologic stage immediately successive to the tectonic fragmentation of the i order palaeosurface (pliocene early pleistocene in age), which is the oldest geomorphologic element of this region (fig. 9). at that time the blockfaulting caused the deepening and widening of the gulf of salerno and allowed the sorrento peninsula to be further uplifted; in the meanwhile the width of the peninsula itself was progressively reduced and the agerola tectonic depression was created. during this period the peninsula was towards the south still wider and lower in elevation than today. subsequently a period of relative tectonic stability occurred and a new generation of low relief landscape (ii order palaeosurface) was formed. uplifted remnants of the ii order palaeosurface occur in several places at elevations from 500 m to 800 m (fig. 2). in fact the agerola graben, whose southern rim at present is open towards the south, by that time was entirely closed and received clastic imputs also from the southern reliefs. these ones had to include also the mountainous area into which a small river catchment had to be nested and fed the clastic infilling of nocella palaeovalley; the sedimentologic analysis of the nocella conglomerates also suggests a source area which extended for some km to the south-east. the palaeovalley had to be flanked by mt. tre calli to the northeast and some other reliefs of similar height (higher than about 800m in any case) to the south-west. these reliefs were part of morphostructural high which close towards the south and fed the alluvial clastic infilling of the agerola depression. furthermore, the s. maria del castello ii order surface has been interpreted as the basinward portion of the low gradient paleoslope on which the nocella river was flowing. other small hanging concave up footslopes (erosional landforms beside moiano, ticciano and massaquano settlements), have been interpreted as erosional and depositional landforms connecting the scrajo-vettica fault scarp to the nocella river valley. after the development of the the ii order palaeosurfaces, the study area was affected by a tectonic phase driven by a nw-trending direction of extension which allow netrending fault scarps to be formed (caiazzo et al., 2000). according to the authors this tectonic event may be ascribed to the beginning of the middle pleistocene. furthermore, the southern segment of the scrajo-vettica fault zone was reactivated as tran94 a. amato g. robustelli fig. 9 main stages of the morphotectonic and the drainage evolution of the study area. c marks s.maria al castello; nn marks nocella site; ff marks mt. faito; ttpp marks s. angelo a tre pizzi; ttcc marks mt. tre calli; a marks agerola; i, ii, iii; iv modified from caiazzo et al. (2000); • • : beheaded valley; � �: relic valley; �: river capture. principali tappe dell’evoluzione morfotettonica e del reticolo idrografico. le lettere cc, nn, ff, ttpp, ttcc, aa, indicano rispettivamente le località di s.maria al castello, il sito studiato di nocella, m. faito, m. s. angelo a tre pizzi, m. tre calli ed agerola. i, ii, iii e iv modificate da caiazzo et al. (2000); • •: valli tronche;� �: valli relitte; �; catture fluviali. 95 sfer fault. the peninsula was progressively reduced by block faulting that affected its southern flank which enlarged the contiguous gulf of salerno and drawing the present-day coastal profile. aacckknnoowwlleeddggeemmeennttss the authors wish to thank prof. a. cinque for the helpful field discussions and the useful comments on early draft of the manuscript. this article benefited from helpful review and suggestions by l. brancaccio and m. sagri. rreeffeerreenncceess aucelli p.p.c., cinque a. & merola d., 1996 discriminazione cronologica di eventi deformativi fragili lungo il margine settentrionale dei monti lattari sulla base di dati geologici e geomorfologici. il quaternario, 9, 319-324. bartole r., savell d., tramontana m. & wezel c. f., 1984 – structural and sedimentary features in the tyrrhenian margin off campania, southern italy. marine geology, 5555, 168-180. bluck b. j., 1979 – structure of coarse grained braided stream alluvium. transactions of the royal society of edinburgh, 7700, 181-221. bonardi g., d’argenio b. & perrone v., 1988 – carta geologica dell’appennino meridionale alla scala 1:250.000. mem. soc. geol. it., 4411, 1341. brancaccio l., cinque a. & sgrosso i., 1976 – la grotta di s. barbara nel contesto della evoluzione geomorfologia della piana di agerola. ann. speleol., c.a.i., napoli, 33. brancaccio l., cinque a. & sgrosso i., 1979 – l’analisi morfologica dei versanti come strumento per la ricostruzione degli eventi neotettonici. mem. soc. geol. it., 1199,, 621-626. bridge j.s., 1993 – description and interpretation of fluvial deposits: a critical perspective. sedimentology, 4400, 801-810. caiazzo c., cinque a. & merola d., 2000 – relative chronology and kinematics of the nw and ne trending faults of the sorrento peninsula (southern apennines). mem. soc. geol. it., 5555, 165-174. cinque a., patacca e., scandone p. & tozzi m., 1993 – quaternary kinematic evolution of the southern apennines. relationship between surface geological features and deep lithospheric structures. ann. geofis., 3366, 249-260. cinque a. 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(ed.). fluvial sedimentology. can. soc. petrol. geol. mem., 55, 605-625. the nocella conglomerates ... ridgway k. d. & decelles p. g., 1993 – stream-dominated alluvial fan and lacustrine depositional systems in cenozoic strike-slip basins, denali fault system, yukon territoty, canada. sedimentology, 4400, 645-666. sacchi m., infusino s. & scarsella e., 1994 – late pliocene-early pleistocene compressional tectonics in offshore campania (eastern tyrrhenian sea). boll. geof. teor. appl., 3366, 469-482. sartori r., 1989 – evoluzione neogenico-recente del bacino tirrenico e i suoi rapporti con le aree circostanti. gior. di geol. it., 3388, 225-240 sartori r., 1990 – the main results of odp leg 107 in the frame of neogene to recent geology of the perityrrhenian areas. in: kastens k. a., mascle j. et al. – proc. odp sci. results, 110077, 715-730. scott k. m., 1988 – origins, behaviour, and sedimentology of lahars and lahar-runout flows in the toutlecowlitz river system. u.s. geol. surv. prof. paper, 11444477--aa, a1-a74. shultz a. w. (1984) – subaerial debris-flow deposition in the upper paleozoic cutler formation, western colorado. j. sediment. petrol., 5544, 759-772. smith g. a., 1986 – coarse-grained nonmarine volcaniclastic sediment: terminology and depositional processes. geol. soc. am. bull., 9977,, 1-10. smith g. a. & lowe d. r., 1991 – lahars: volcanohydrologic events and deposition in the debris flow-hyperconcentrated flow continuum. in: fisher r. v., smith g. a. (eds) sedimentation in volcanic settings. sepm, spec. pubbl., 4455, 59-70. sohn y. k., rhee c. w. & kim b. c., 1999 – debris flow and hyperconcentrated flood-flow deposits in an alluvial fan, northwestern part of the cretaceous yongdong basin, central korea. j. geol., 110077, 111-132. steel r. j. & thompson d. b. (1983) – structures and textures in triassic braided stream conglomerates (“bunter” pebble beds) in sherwood sandstone group. north staffordshire. england. sedimentology, 3300, 341-367. todd s. p. (1989) – stream-driven, high-density gravelly traction carpets: possible deposits in the trabeg conglomerates formation, sw ireland and some theoretical considerations of their origin. sedimentology, 3366, 513-530. waresback d. b. & turbeville b. n., 1990 – evolution of a plio-pleistocene volcanogenic-alluvial fan:the puye formation, jemez mountains, new mexico. geol. soc. am. bull., 110022, 298-314. 96 a. amato g. robustelli ms. ricevuto il 26 marzo 2002 testo definitivo ricevuto il 28 maggio 2002 ms. received: march 26, 2002 final text received: june 28, 2002 amq short notes 26_2 zerboni divito monegato available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 25 (2), 2012, vii ix report on the aiqua 2013 summer school "the impact of volcanic eruptions on landscape, environment and human settlements (multidisciplinary perspectives: geological, archaeological and biological)” mauro a. di vito1, giovanni zanchetta2, sandro de vita1, paola romano3, pierfrancesco talamo4 1 istituto nazionale di geofisica e vulcanologia, sezione di napoli osservatorio vesuviano, naples, italy 2 dipartimento di scienze della terra, università degli studi di pisa, italy 3 dipartimento di scienze della terra, università degli studi federico ii di napoli, italy 4 soprintendenza speciale per i beni archeologici di napoli e pompei, naples, italy corresponding author: m.a. di vito <mauro.divito@ov.ingv.it> abstract: a brief summary of the activities carried out during the aiqua 2013 summer school held from the 27th to 31st may 2013 at the vesuvius observatory. the course provided an opportunity for students and researchers from different academic backgrounds to present and discuss topics of great scientific and human interest concerning the impact of volcanic eruptions on people and the landscape, starting from actual examples in the vicinity of naples. keywords: volcanology, archaeology, climate, botany, palaeontology, pedology. the aiqua 2013 summer school, held at the vesuvius observatory (naples headquarters of the ingv) from 27th to 31st march 2013, received an encouraging level of participation in terms of both subscribers and speakers. notwithstanding the economic difficulties that affect young people in particular, twenty-seven enrolled: young researchers, phd students and undergraduates from the length of italy, and one from switzerland. the speakers, all research workers of international standing who took part with enthusiasm and without remuneration, provided classes of high educational and scientific calibre. the texts of these lessons, in the form of short scientific articles, were published in a journal entitled miscellanea (di vito et al., 2013) and distributed beforehand to teachers and students; they may be found online at www.ingv.it. this collection, thanks to keen participation from all the speakers and fig. 1 field trip – avella stop. mauro di vito is discussing the impact of past eruptions on the landscape. the professionalism of the ingv editorial staff, was made available online prior to the start of the course and has also been printed, with financial support from the vesuvius observatory. the lessons all shared a common denominator, an emphasis upon how an integrated multidisciplinary approach can enable the reconstruction of the human and territorial impact of extreme events such as volcanic eruptions and related phenomena, and an understanding of how the many peoples who have inhabited the naples region – of different cultures and modes of social organization – have reacted to these events. despite the results obtained by much specialist research in this area, there are still few multidisciplinary studies in which diverse disciplines have worked in close and continuous collaboration. the field excursions (figs. 1 and 2) involved concrete examples of recently-studied cases, demonstrating how the concepts explained during the lectures have been applied to resolve problems which posed difficulties for individual specialists – for whom familiarity with the routine application of their own procedures leads to the risk of missing information essential for the comprehension of the lecturer title mauro a. di vito a geological perspective on the study of human responses to volcanic activity: examples in campania mauro a. di vito somma vesuvius: history of eruptions and their territorial impact roberto isaia tephrostratigraphy of phlegraean fields volcanism during the last 15 ka sandro de vita structural geology and volcanological evolution of the isle of ischia monica piochi, angela mormone petrology and isotopic geochemistry in tephrostratigraphical correlations: examples from neapolitan volcanoes daniela giampaola, giuliana boenzi effects on human life of volcanic activity: archaeological evidence from central naples adele bertini role of volcanic activity in quaternary climate change vincenzo amato holocene climatic variations: examples of morpho-sedimentary change inferred from the archaeotephro-stratigraphic record of campania (41°n, south italy) biagio giaccio chronology and ecological factors regarding the middle palaeolithic – upper palaeolithic transition in europe in the light of the campanian ignimbrite eruption (39 ka) giovanni zanchetta syneruptive and intereruptive debris-flow on the campanian apennines: a geological perspective fabio terribile genesis, evolution and properties of volcanic soils in the campanian countryside gaetano di pasquale transformations of wooded and grass-covered landscapes in campania: information from the study of wood and charcoal in natural and anthropic contexts filippo terrasi the importance of 14c dating in chronostratigraphy and palaeoenvironmental work giovanni zanchetta continental isotope-based palaeoclimatology and the climatic evolution of the mediterranean christophe morhange holocene relative sea level changes: an insight from volcanological and archaeological data aldo cinque geomorphological evolution of the sorrento peninsula valleys after the vesuvian eruption of ad 79 aldo marturano pompeii and the insula of the chaste lovers: natural phenomena, transformations of the terrain and interactions with the manmade environment elda russo ermolli pollen analysis: an important tool for reconstructing palaeolandscapes and palaeoclimates pierfrancesco talamo campanian cultural sequence and volcanic events from the neolithic until the end of the bronze age paola romano reconstructing ancient coastlines in naples from geological and geomorphological evidence elena laforgia impact of volcanic eruptions in the area north of naples: new data from recent excavations costanza gialanella effects on human life of volcanic activity: the archaeological evidence from the isle of ischia valentino di donato palaeontology’s contribution to the understanding of archaeological contexts: methods and campanian case-studies laura sadori using plant micro-remains for reconstructing palaeoenvironments and evaluating the effects of human activity: the lakes of lazio marco pacciarelli exceptional development of settlements from neolithic to iron age on soils of volcanic origin in tyrrhenian calabria table 1. topics covered during the aiqua 2013 summer school field leaders field trip mauro a. di vito, gianni zanchetta, pierfrancesco talamo, giuseppe vecchio, nicola castaldo monteforte (distal sequences in the apennines); avella (alluvial fans at the apennine-campania plain junction); s. paolo belsito (reconstruction of huts of the nola early bronze age village); cimitile (early christian churches and the ad 472 debris-flow) mauro a. di vito, sandro de vita, pierfrancesco talamo, aldo marturano, paola romano, aldo cinque, costanza gialanella, maria paola guidobaldi, paola miniero, grete stefani pompeii (house of the chaste lovers); herculaneum (the pre-ad 79 coastline); phlegraean fields (baia castle, lake averno and monte nuovo); pozzuoli (roman marketplace) table 2. field trips held during the aiqua 2013 summer school di vito a. et al. viii phenomena observed and their effects on humans and the environment. the fundamental purpose of the course was to stimulate debate and cooperation between the diverse branches of knowledge involved and initiate the formation of professionals able to meet the new challenges that the humanistic and natural sciences must face in order to make real progress in the understanding of past phenomena and guide an informed and sustainable use of the land. in tables 1 and 2 the topics covered and relevant speakers are listed – all of whom are warmly thanked for their contribution to the success of this initiativeand the field trips, held during the course. references di vito m.a., de vita s. (eds) 2013. compendio delle lezioni, scuola estiva aiqua 2013, l’impatto delle eruzioni vulcaniche sul paesaggio, sull’ambiente e sugli insediamenti umani – approcci multidisciplinari di tipo geologico, archeologico e biologico. napoli 27 – 31 maggio 2013, miscellanea ingv, 18:1-136. fig. 2. field trip – the excursion ended at the baia castle in the western campi flegrei. ms. received: september 6, 2013 final text received: september 6, 2013 aiqua 2013 summer school ix x imp.bertini eeaarrllyy ttoo mmiiddddllee pplleeiissttoocceennee cchhaannggeess ooff tthhee iittaalliiaann fflloorraa aanndd vveeggeettaattiioonn iinn tthhee lliigghhtt ooff aa cchhrroonnoossttrraattiiggrraapphhiicc ffrraammeewwoorrkk aaddeellee bbeerrttiinnii department of earth sciences and museum of natural history, section of geology and paleontology, university of florence, via g. la pira 4, 50121 florence italy. abertini@geo.unifi.it abstract palynological data from selected pleistocene italian sites are presented. the chronostratigraphic framework of floral and vegetational events illustrates the development of cooler climates during the early and middle pleistocene. floral and vegetational response to glacial/interglacial cycles, as well as major floristic and vegetal replacements (e.g. taxodiaceae, cathaya, tsuga) are analysed with special attention to latitudinal and altitudinal gradients and to the different physiography of italy. the pollen flora shows marked changes both at the beginning of the pleistocene as well as at the time of the mid-pleistocene climate transition, when a major decrease in temperature, during steppe and forest phases, occurred. alternations of artemisia steppe and temperate to warm-temperate deciduous forest mark the overall glacial-interglacial vegetation changes in italy. glacials, however, do not correspond to dramatic drops of moisture in northern italy. cycles here are characterized by the alternating spread of deciduous broad-leaved forests and altitudinal coniferous forests (mainly picea) with no significant occurrence of steppe vegetation. several sites from northern, central and southern italy are described; reference sections permit correlations also of sites with poor time-diagnostic content. the quality of data is crucial in the application of advanced methodologies in palynology for reliable climate quantifications as well as for the elaboration of vegetation paleomaps. riassunto la palinologia rappresenta, potenzialmente, un importante strumento per la ricostruzione paleoambientale durante il pleistocene. durante questo intervallo di tempo la composizione floristica e la vegetazione sono ancora diverse da quelle presenti attualmente; un complesso melange di taxa aventi oggi una distribuzione geografica separata domina infatti le associazioni palinologiche. numerosi taxa, ancora presenti nel nostro paese (e.g. quercus, picea, abies), sono associati ad altri aventi invece una distribuzione asiatica e/o americana (e.g. taxodiaceae, cathaya, tsuga, carya). il progressivo fenomeno di raffreddamento, già cominciato durante il pliocene, determina la progressiva scomparsa dei taxa relativamente più termofili come ad esempio taxodiaceae, cathaya, parrotia persica, tsuga, cedrus e liquidambar. tali scomparse si verificano, nei diversi paesi europei e del litorale mediterraneo, in modo diacrono risultando fortemente influenzate da diversi gradienti climatici; la scomparsa delle taxodiacee, avviene in modo tempo-trasgressivo all’interno della stessa penisola italiana. tali eventi, possono, perciò, essere utilmente usati, solo se inseriti all’interno di un quadro cronostratigrafico di riferimento. la necessità di integrazione del record palinologico con altri strumenti stratigrafici è ribadita anche dal carattere spesso discontinuo di alcuni record così come dalla variabilità della vegetazionale locale. l’integrazione con elementi tempo-diagnostici quali la tefrostratigrafia o la magnetostratigrafia consente di inserire gli eventi ecobiostratigrafici in uno schema temporale; in tal modo essi diventano a loro volta elementi tempo-diagnostici in grado di migliorare la risoluzione stratigrafica; cio’ rende possibile anche un loro corretto utilizzo per la definizione e la caratterizzazione di unità climatostratigrafiche e di biozone. in tal modo la palinologia diventa uno strumento efficace ed indispensabile per le ricostruzioni stratigrafiche e paleoambientali. le diverse successioni italiane analizzate in questo lavoro di sintesi sono state selezionate sulla base della qualità del dato pollinico e della presenza di un adeguato quadro cronostratigrafico di riferimento. ciò ha consentito di tracciare, in accordo con i cambiamenti relativi alla latitudine, altitudine e alle diverse caratteristiche fiosiografiche dei siti analizzati, la risposta della flora e della vegetazione ai cicli glaciale/interglaciale (g/i) durante il pleistocene inferiore e medio. la palinoflora, già depauperata all’inizio del pleistocene, subisce un progressivo ulteriore impoverimento in corrispondenza della transizione climatica del pleistocene medio quando un’importante diminuizione della temperatura marca sia le fasi forestali che steppiche. in italia, i cicli g/i determinano, generalmente, un’alternanza tra una vegetazione di tipo aperto prevalentemente steppica (ad artemisia) sotto un clima arido da fresco a freddo ed una forestale dominata dalle latifoglie decidue sotto un clima umido e caldo-temperato. tuttavia, nessuna importante diminuizione dell’umidità con conseguente espansione della vegetazione steppica è stata registrata durante i glaciali, nei siti dell’italia settentrionale; qui, infatti, i cicli g/i sono caratterizzati dalla contrapposizione tra foreste di conifere di altitudine (principalmente a picea) e foreste di latifoglie decidue. l’analisi floristica e vegetazionale delle diverse successioni analizzate evidenzia la buona potenzialità di alcune di loro a costituire delle sezioni di riferimento rappresentative delle diverse aree chiave della nostra penisola (nord, centro, sud). la definizione e la calibrazione dei principali eventi floristici e vegetazionali facilita le correlazioni sia a piccola con sezioni geograficamente vicine a quelle di riferimento, non provviste di nessun altro supporto cronologico – che a grande scala. i dati selezionati potranno essere efficacemente utilizzati nell’ambito delle quantificazioni climatiche e per la ricostruzione di paleomappe di vegetazione; entrambi questi approcci sono già stati applicati con successo a siti neogenici. key words: pollen, flora, vegetation, climate, early-middle pleistocene, italy. parole chiave: polline, flora, vegetazione, clima, pleistocene inferiore e medio, italia. il quaternario italian journal of quaternary sciences 1166(1bis), 2003, 19-36 11.. iinnttrroodduuccttiioonn pollen represents, potentially, an important mean for the reconstruction of the patterns and processes of vegetation and climatic changes during the pleistocene. at this time, the floral composition and vegetation of the mediterranean and central european areas were still quite different from those present today; new species seldom appear and the disappearance of some thermophilous taxa (e.g. taxodiaceae, parrotia persica, cedrus, liquidambar) has a diachronous character (e.g. zagwijn, 1975; suc, 1986; combourieu-nebout, 1987; fusco, 1996). the palynologic content must thus be used warily in describing biozones or climatostratigraphic units, especially when they do not make part of an established chronostratigraphic framework. several 20 a. bertini palynostratigraphic correlations made in the past (e.g. those based on the disappearance of taxodiaceae interpreted as an isochronous event; lona et al., 1969; lona & bertoldi, 1972) are incorrect (e.g. zagwijn, 1975; bertolani-marchetti et al., 1979; michaux et al., 1979) because based on two hazardous assumptions: the belief that the same (or similar) pollen assemblage zones in separate sections denote synchronous pollen signals; and the subsequent chronostratigraphic significance (e.g. tiberian phase and boundary; lona et al., 1969; lona & bertoldi, 1972) attributed to some of these “ecobiostratigraphic” phases. this blurred the boundary between biostratigraphy and chronostratigraphy. because of local vegetational variability and of the scantiness of many records (notably that from continental areas) palynology needs to be associated to other stratigraphic tools. in fact, the integration of time-diagnostic evidence (e.g. magnetostratigraphy and tephrostratigraphy) gives chronological value to ecobiostratigraphic events, thus enhancing stratigraphic resolution. hence, correlation at local to regional scale between the successions lacking time-diagnostic elements is also made possible. moreover, contrary to other fossils, palynomorphs, being contained in both marine and non-marine sediments, permit the correlation between onshore and offshore successions. all this makes palynology a very powerful tool for stratigraphic and palaeoenvironmental reconstructions. these observations justified the selection of the lower to middle pleistocene successions of italy discussed in the paper (figs. 1-2). the responses of the flora and vegetation to the glacial/interglacial cycles with special attention to latitudinal and altitudinal gradients are analysed, together with the major vegetation replacements. 22.. ssttrraattiiggrraapphhiiccaall sseettttiinngg the neogene regional and global events (e.g. messinian salinity crisis, early pliocene transgression, late pliocene expansion of the arctic ice cap and consequent start of glacial/interglacial cycles), strongly affected the successive pleistocene history of the mediterranean settings. from about 2.6 to 0.9 ma, the glacial/interglacial fluctuations (g/i cycles) were dominated by orbital obliquity cycles, which have a periodicity of 41 ka; fluctuations of 100 ka, related to orbital eccentricity cycles, prevailed thereafter (ruddiman et al., 1989). this shift toward a more extended periodicity and amplitude indicates more intense glacial conditions, particularly between ca 0.9 and 0.6 ma. in land settings, this modification in the g/i cycles produced a significant change in the vegetation and flora: steppes spread, while extreme thermophilous taxa, especially those distributed in subtropical areas today, progressively demised. the important geomorphic changes linked to the uplift of the apennines also produced an important reorganization and restructuring of vegetation. increased elevation led to climatic conditions similar to those found at higher latitudes; this also gave rise to diffig. 1 location map of the selected sections 21early to middle pleistocene changes ... f ig . 2 s tr a tig ra p h ic a l l o ca tio n o f th e s e le ct e d s e ct io n s 22 a. bertini ferent belts of vegetation at different altitudes. all these modifications in climate and vegetation inexorably affected large mammal assemblages as well. in fact, important turnovers are detected in the villafranchian mammal faunal communities (e.g. torre et al., 2001; fig. 2). a strong drop in ruminant diversity, as well as the arrival of social carnivores, mark the end of the reunion subchron and the onset of the olduvai subchron (azzaroli et al., 1988). this is known as the “wolf-event” (azzaroli, 1983; 1995; rook & torre, 1996). another change in the villafranchian faunal community, marked by the arrival of mammuthus (archidiskodon) and equus, and known as the “elephant-equus event”, had occurred shortly before, approximately at the gauss/matuyama transition (azzaroli, 1995; torre et al., 2001). the low ruminant diversity persisted until the middle pleistocene, when it grew again, equalling the final pliocene levels, thanks to the arrival of new incomers. the successions analysed in this work are mostly located in the pre-alps and in the apennines (fig. 1). the schematic stratigraphic position of these sites are shown in figure 2. the triassic to paleogene marine successions exposed in the southern alps were involved in the final miocene pulses of the alpine deformation which caused the emergence of most of this area. several valleys in the pre-alps, which had formed before the end of the messinian (bini et al., 1978), were filled with pliocene marine sediments (bini et al., 1978; brambilla et al., 1983; brambilla & lualdi, 1987; violanti, 1991). during the plio-pleistocene, the upper lombardy plain emerged. fluvial sediments deposited during a successive phase of aggradation. tributary valleys finally dammed at the end of the aggradation phase, and lacustrine basins were formed, as for example those of leffe (cremaschi & ravazzi, 1995) and fornaci di ranica (ravazzi et al., in press). several terraced deposits were formed during the successive middle and late pleistocene fluvial downcut. the apennines started to arise in the latest cretaceous, during the eo-alpine phase. from the late tortonian to the early middle pleistocene, extensional faulting affected the inner sectors of the apennine chain, generating numerous, relatively small, eastward-progressing and younger, marine and continental basins, extended wsw of the orographic divide. three major successions of marine to continental deposits characterize the peri-tyrrhenian extensional areas (an outline can be found in ghisetti & vezzani, 1999). martini & sagri (1993), and bossio et al. (1998) described the successions outcropping in the northern apennines, while cinque et al. (1993) the ones exposed in the southern apennines. compressional basins (“piggyback” and “foredeep” basins; ori & friend, 1984; riccilucchi, 1986; 1990) formed on the adriatic side of the mountain divide. 33.. mmaatteerriiaallss aanndd mmeetthhooddss the pleistocene sections selected for this study (figs. 1, 2) are among the most dependable from the chronological viewpoint. the main stratigraphical and geological information is summarized below, whereas the pollen records are discussed in the following paragraphs. 11. the ssttiirroonnee succession outcrops on the banks of the stirone river, along the northern apennine foothills, some 28 km west of parma (northern italy). because of its rich stratigraphical and paleontological documentation, it is one of the best known pliocene to pleistocene successions of northern italy (e.g. papani & pelosio, 1963; pelosio & raffi, 1974; raffi, 1982; iaccarino & pugliese, 1988; capotondi, 1992; mary et al., 1993; channel et al., 1994; monegatti & pelosio, 1994; iaccarino, 1996). the stirone succession consists, from the base upwards, of about 900 m of lower to upper pliocene marine deposits and of over 100 m of pleistocene infralittoral sediments, with intercalations of brackish and fresh water beds. the palynological content of the pliocene sediments was analysed by bertini (1992; 1994a, b; 2001) and bertini & vannucchi (1993), whereas that of the upper pliocene to lower pleistocene sediments by lona & bertoldi (1972), becker-platen et al. (1977) and bertolani-marchetti et al. (1979). 22. the uuppppeerr vvaallddaarrnnoo (central italy) is one of the most extensive plio-pleistocene intermontane basins of the northern apennines. it is located 35 km se of florence between the chianti mountains and the pratomagno ridge. it is filled with some 550 m of fluviolacustrine deposits which can be divided into three main sedimentary successions (e.g. merla & abbate, 1967; azzaroli & lazzeri, 1977; abbate, 1983; magi & sagri, 1994) of middle pliocene to pleistocene age on the basis of bioand magnetochronological evidence (torre et al., 1993, 1996; albianelli et al., 1997; napoleone et al., this volume). pollen analyses were carried out by bertini (1994b; in press), bertini & roiron (1997) and mazza et al. (submitted). 33. the sseemmaaffoorroo--vvrriiccaa composite section outcrops 4 km south of crotone (calabria, southern italy). it consists of about 451 m of pliocene and pleistocene marine blue grey silty-marly claystones with sapropelic laminite and cineritic intercalations. at vrica, the base of the marine claystones, which conformably overlies the sapropelic marker bed "e", marks the onset of the pleistocene series (aguirre & pasini, 1985; basset, 1985; van couvering, 1997). palynological analyses were carried out by bertolani-marchetti (in selli et al., 1977), nakagawa et al. (1980; 1997), combourieunebout & vergnaud-grazzini (1991), and combourieunebout (e.g. 1993; 1995). 44. the marine plio-pleistocene section of ggeellaa, in sicily (agrigento, southern italy), is well known in literature thanks to the studies of rio et al. (1984) and sprovieri et al. (1986). palynological studies there were carried out by bertoldi et al. (1989). 55.. llee ccaasstteellllaa is a marine section located on the ionian side of northern calabria (crotone basin). it was first described by emiliani et al. (1961). calcareous nannofossil biostratigraphy (raffi & rio, 1980) revealed a fairly long hiatus at the sandy “marker bed” of emiliani et al. (1961). pollen records are available from the upper part of the late pliocene, as well as from the middle part of early pleistocene (bertoldi, 1977; bertoldi et al., 1989). 66.. the ccaammeerroottaa basin, in the cilento promontory, is a structural depression formed during the late pliocene extensional tectonics that disrupted the eastern margin of the southern tyrrhenian basin (borrelli et al., 1988). here palynological research was 23early to middle pleistocene changes ... performed in sediments of an about 40-50 m thick lacustrine succession of clays and marls with recurrent tephra and peat beds in the upper portion (baggioni et al., 1981; brenac, 1984; russo-ermolli, 1999). unfortunately, these deposits are void of significant time-diagnostic elements. the only sure stratigraphical reference are santernian marine deposits which unconformably cap the sequence. 77. the lleeffffee section, in the lombardian pre-alps, consists of a plio-pleistocene continental succession of clays, brown-coals, peats, gyttja, and biogenic calcareous laminites. more precisely, the succession extends between the top of the olduvai (muttoni, in progress, and ravazzi, pers. com. 2002, claim that it possibly reaches the base of the olduvai) and the base of the jaramillo (which however was never located). the palynologic content of this sequence was studied by lona (1950), lona & follieri (1957), lona & bertoldi (1972), ravazzi (1993: see for geological and stratigraphical references), ravazzi & rossignol-strick (1994; 1995), ravazzi & moscariello (1998) and pini & ravazzi (2002). 88. the llaammoonnee succession, in the north-eastern apennines, consists of marine grey-blue clays of the argille azzurre fm. this succession is santernian to emilian in age, on the basis of its foraminiferal content (vaiani, 1996). palynological studies have been carried out in two separate sections (fusco, 1996). the first one contains the santernian/emilian boundary, marked by the appearance of the benthonic foraminifer hyalinea baltica (pasini & colalongo, 1994). this same taxon is distributed throughout the whole second section, which therefore is dated to the emilian. 99. the ppiieettrraaffiittttaa lacustrine succession outcrops in the tavernelle basin, which forms the upper valley of the nestore river (umbria, central italy). the succession consists of clays, peaty clays and lignite beds. the latter have yielded numerous fossil remains of vertebrates, invertebrates, and macroflora. the mammal remains have been referred to the farneto faunal unit (late villafranchian mammal age; gliozzi et al., 1997). an early pleistocene age is also consistent with the inverse magnetic polarity detected in the lignite beds (napoleone & albianelli, pers. com. 2002). ricciardi (1961) and lona & bertoldi (1972) carried out the palynological analyses of this succession. 1100.. mmoonnttaallbbaannoo iioonniiccoo, southernmost part of the bradano trough (basilicata, southern italy). this marine succession consists of about 400 m of silty clays (“argille subappenine” formation), with nine volcanoclastic intercalations. the succession was found to straddle the lower-middle pleistocene boundary on the basis of nannofossil and magnetostratigraphic evidence (e.g. ciaranfi et al., 1996; 2001). preliminary palynological analyses were performed by suc (suc, pers. com. 1999). 1111. the mmoonnttee ssaann ggiioorrggiioo succession, north of caltagirone (sicily), consists of 150 m of marine clayey and sandy marls intercalated to clays. palynological analyses were carried out along a 60 m section where the continental and marine records indicated a dating from 1.23 to 1.095 ma (dubois, 2001). 1122.. ssaannttaarrccaannggeelloo is a pliocene to pleistocene satellite basin in the southern apennines (basilicata, southern italy). palynological research has been carried out in the lacustrine deposits of the san lorenzo unit (bertini in sabato et al., in press; bertini, in progress). the latter is an over 200 m thinly bedded claystone and silty claystone with sandstone, carbonate and volcanoclastic intercalations. a late biharian mammal assemblage was found in this succession (masini et al., in press). palaeomagnetic investigations allow the identification of the jaramillo subchron, as well as the base of the brunhes chron (sabato et al., in press). 1133. the ccoollllee ccuurrttii and cceessii fluvio-lacustrine basins are located in the umbria-marchean apennine mountains (central italy), at about 850 m and 820 m above sea level, respectively. they were formed in the early to middle pleistocene when extensional tectonics affected the mountain chain (e.g. coltorti et al., 1998). the colle curti mammalian faunal assemblage defines the homonymous faunal unit, which marks the beginning of the galerian mammal age in italy (e.g. ficcarelli et al., 1997). magnetostratigraphical research identified the c1r.2r p.p., c1r.1n (jaramillo), c1r.1r and c1n p.p. (brunhes) chrons and subchrons. pyroclastic sediments about 30 m above the top of the section, yielded an ar/ar date of 424 ka (coltorti et al., 1998). the palynological content of both sections was studied (e.g. bertini, 2000). 1144. the lacustrine succession of ffoorrnnaaccii ddii rraanniiccaa, at the outlet of the seriana valley in the bergamo foothills (northern italy). multidisciplinary studies carried out throughout a 13 m long-core suggest that the sedimentation occurred in the late early pleistocene, apparently during the jaramillo subchron. nevertheless, the impossibility to discriminate between cervalces latifrons and c. carnutorum do not exclude a correlation to the cryptochron cobb (ravazzi et al., in press). 1155. the vvaallllee ddii mmaanncchhee section, south-east of the san mauro marchesato area, in the crotone basin (southern italy). here the middle pleistocene deposits underwent detailed stratigraphical studies (see in massari et al., 2001 for references). the valle di manche section contains the three main units defined in the san mauro group (san mauro 1, 2, 3) extending approximately just above the top of the jaramillo and the “parmenide ash” key bed. the brunhes matuyama boundary correlates with the“pitagora ash”, in the mainly muddy san mauro 2 unit. capraro in massari et al. (2001) performed palynological analyses from the base to the lower part of s. mauro 3, which mainly consists of prograding sand bodies. 1166.. llaa ppiinneettaa - iisseerrnniiaa. the archaeological site of la pineta lies at about 450 m a.s.l in the intermontane isernia–venafro lacustrine basin, in the upper part of the volturno valley (southern italy). the basin was filled up between 870 ±150 and 520 ±50 ka ago (van otterloo & sevink, 1983). five units have been recognized (cremaschi, 1983; cremaschi & peretto, 1988), with a lacustrine episode at the base. the latter is overlain by a fluvial unit containing mammal remains and lower paleolithic lithic industry. delitalia et al. (1983) obtained a k/ar dating of 736 ±40 ka (for the archaeological bed). such a dating, however, was first challenged by von koenigswald & kolfschoten (1996) because of the occurrence of arvicola cantiana, and afterwards by belluomini et al. (1997) who obtained an amino-acid dating of 550 ±140 ka. pollen analyses were carried out by lebreton (2001; 2002). 1177.. ppiiaanniiccoo--sseelllleerree, south of the italian alps, consists of an about 50 m varved lacustrine succession 24 (moscariello et al., 2000). the k/ar dating of a distal tephra in the sequence gave an age of 779 ± 13 ka. palaeomagnetic analyses consistently detected the matuyama/brunhes transition. the latter is dated 780 ka (pinti et al., 2001) and correlates both with the marine oxygen isotopic stage 19 (mis 19) and with the oldest interglacial phases of the cromerian complex of central europe (e.g. turner, 1996). 1188.. vvaalllloo ddii ddiiaannoo is a large tectonic basin in the campanian apennines (southern italy). here a borehole about 150 m deep was drilled through a lacustrine sequence. a 601 ± 7 ka 40ar/39ar dating at the base of the sequence, matched with oxygen isotopic data, suggested that the pollen record (e.g. russo-ermolli, 1994; russoermolli et al., 1995) covers a 650 to ca 450 ka span (mis 16 to 13) (e.g. russo-ermolli & chedaddi, 1997). 1199.. tthhee aacceerrnnoo bbaassiinn (southern italy) represents a middle pleistocene tectonic paleolake formed in the southern apennines. a 98 m continuous coring drilled through a sequence consisting, from the base upwards, of fluvial conglomerates, silt and white marl alternations, and fluvial conglomerates with silt and sand interfingings. thirty pyroclastic beds were identified. the thickest tephra bed correlates with mis 9 and 8 because of the presence of the lower white trachytic tuff marker horizon dated to 297 ka (munno et al., 2001). pollen analyses of this sequence were carried out by elda russo-ermolli (2000). 44.. tthhee eeaarrllyy pplleeiissttoocceennee the marine composite section of sseemmaaffoorroo--vvrriiccaa (crotone, calabria) is used as reference to locate stratigraphically the main late pliocene to early pleistocene floral, vegetational and climatic changes. in the vrica section, in particular, the gssp of the base of the pleistocene series has been ratified, whereas the calabrian stage as well as the emilian and santernian substages have only been proposed (aguirre & pasini, 1985; basset, 1985; pasini & colalongo, 1994; ruggieri & sprovieri, 1997; pasini & colalongo, 2001). successive studies (e.g. hilgen, 1991; zijderveld et al., 1991; lourens et al., 1966a,b; 1998; raffi, 2002) provided further stratigraphic evidence completing the original definitions. zijderveld et al. (1991) repositioned the plio-pleistocene boundary (ppb) placing it just below the top of the olduvai subchron. lourens et al. (1996a) showed that the pleistocene part of the vrica section ranges from the standard oxygen isotope stage 65 to 36, stressing the substantial difference from previous interpretations (combourieu-nebout & vergnaudgrazzini, 1991; sprovieri, 1993). in contrast to oceanic sequences, the base of the large gephyrocapsa (blg) zone correlates with stage 55 and not with stage 48 (or with the top of stage 49) (raffi et al., 1993; lourens et al., 1998; raffi, 2002). consequently, the fad of the benthic foraminifer hyalina baltica does not match with the base of the large gephyrocapsa zone. by carrying out the most detailed and accurate palynological studies of the plio-pleistocene composite sections of southern italy, combourieu-nebout (e.g. 1993; 1995) reconstructed the changes in vegetation and climate during the 2.46 to 1.36 ma time span. the main vegetation changes were shown to closely match global climatic variations (e.g. combourieu-nebout & vergnaud–grazzini, 1991). forest to open herbaceous vegetation fluctuations, which reflect the climatic oscillations linked to glacial/interglacial cycles, are documented from the base of the semaforo section (ca at 2.46 ma). likewise other mediterranean sites (see references in suc et al., 1995), the succession of four main vegetational assemblages attests to a gradual transition from warm and moist (interglacials) to cold and dry (glacials) conditions. the start of an interglacial event is marked, at first, by the expansion of deciduous forests, and then, by that of subtropical moist forests indicating an increase in temperature followed by an increase of the humidity. subtropical moist forests progressively reduced from the late pliocene on. the successive increase of high-altitude coniferous forest taxa indicates a temperature drop but no marked variations in humidity. finally, the considerable spread of open vegetation with artemisia indicates a substantial decrease in humidity. g/i cycles are marked by four following vegetation units in northern italy as well. this is clearly documented in the marine succession of llaammoonnee (north-eastern apennines; fusco, 1996), which is more or less equivalent in time to the vrica section. cycles, though, differ from those described at vrica (e.g. combourieu-nebout, 1993) because of the lesser expansion of herbs (especially artemisia) and wider spread of picea. the diffusion of montane arboreal vegetation, in particular picea, during glacial phases, as well as the limited expansion of the herbaceous vegetation, both in time and space is attested to in several plio-pleistocene marine and continental deposits of northern italy (leffe: lona, 1950; ravazzi & rossignol-strick, 1995; castell’arquato: lona, 1962; lona & bertoldi, 1972; stirone, pliopleistocene portion: lona & bertoldi, 1972; bertolanimarchetti et al., 1979; pliocene portion: bertini, 2001; marecchia valley: rio et al., 1997). a phase characterized by high percentages of artemisia but associated to picea and larix, is recorded from the upper part of the early pleistocene continental succession of lleeffffee (lombardy pre-alps) (ravazzi & rossignol-strick, 1995). the limited expansion of steppe taxa seems due to local climatic constraints existing at the time in northern italy, more than to the apparent result of some taphonomic bias, or insufficient chronologic resolution. this strengthens the hypothesis that, roughly since the pliocene, the po region had a very peculiar vegetation and climate (bertini, 2001; fauquette & bertini, in press). plio-pleistocene glacial-interglacial cycles of continental intermontane sequences of central italy have intermediate characteristics between those of southern and northern italy. typical examples are those of the uuppppeerr vvaallddaarrnnoo (e.g. bertini, 1994b; albianelli et al., 1995; torre et al., 1996; albianelli et al., 1997; bertini, in press), the tiber basin (pontini, 1997; pontini & bertini, 2000; pontini et al., 2002), and ppiieettrraaffiittttaa (lona & bertoldi, 1972). on the basis of palynological, biostratigraphical and isotopical evidence from southern italy, bertoldi et al. (1989) observed a different response of vegetation to g/i cycling. in the upper pliocene to lower pleistocene sites of llee ccaasstteellllaa and ggeellaa, in particular, these authors proposed that glacials are marked by forests, while interglacials by open vegetation. a. bertini in the light of the information presented above, it is apparent that repeated g/i cycles contributed to the compositional and structural changes in the vegetation. the upper pliocene of vrica is particularly enlightening. a significant demise of the taxodiaceae forests is attested to from about 2.38 ma on, followed by a spread of cathaya, especially from ca 1.92 to 1.74 ma, as well as of artemisia, from ca 1.87 ma on. in the course of the same interval, warm temperate woodlands expanded at the expense of subtropical forests. the same occured in the upper valdarno, but the record in this case is rather less continuous (bertini, 1994b; bertini, in press). the distribution of taxodiaceae in space and time, as well as their stratigraphical implications during the upper pliocene to early pleistocene time span, are analysed in more detail in paragraph 6.1. the arrival of the large gephyrocapsa, at about 1.56 ma, and successively of hyalina baltica at the santernian-emilian boundary about 1.49 ma, characterizes the marine realm. on lands, a general expansion of open vegetation at this time, in particular of steppe taxa, such as artemisia, a taxon indicative of dry conditions, is recorded at vrica. here, roughly after 1.47 ma (i.e. above laminite q), altitude trees reach their highest percentages, tsuga replacing cathaya in forest associations. this indicates cooler but relatively moist conditions. at lamone (fusco, 1996), in northern italy, a similar trend is observed near to the occurrence of hyalina baltica. a well marked cyclic expansion and dynamism of different vegetations can also be observed. a similar evolution is documented at stirone (lona & bertoldi, 1972; bertolani-marchetti et al., 1979) and leffe (ravazzi & rossignool-strick, 1995). in the latter, in particular, high resolution pollen analyses recently permitted the identification of eleven cyclic changes in vegetation and climate (pini & ravazzi, 2002; in progress) from the end of the late pliocene to the early pleistocene, just before the jaramillo subchron. palynological evidence stops at about 1.36 ma at vrica. additional information from 1.23 and 1.095 ma (the lower part of the sicilian) is available at mmoonnttee ssaann ggiioorrggiioo (caltagirone, sicily). here, glacial/interglacial cycles recall those detected at vrica, with only minor differences (dubois, 2001). 55.. tthhee llaattee eeaarrllyy aanndd mmiiddddllee pplleeiissttoocceennee the most complete late early and middle pleistocene marine and continental successions outcrop in southern italy. the marine successions permit the formal definition of standard pleistocene chronostratigraphic units. the mmoonnttaallbbaannoo jjoonniiccoo section (basilicata, southern italy), with its first occurrence of gephyrocapsa sp. 3 near the top of the jaramillo subchron and in correlation with oxygen isotopic stage 25 (ciaranfi et al., 2001), was the proposed gssp (global boundary stratotype section and point) of the middle pleistocene. it is an alternative to the japanese section of boso peninsula, where kumai’s (1996) proposed gssp lies in the proximity to the brunhesmatuyama magnetic reversal. unfortunately, a pilot survey revealed that the uppermost part of the analysed samples from montalbano jonico section are barren in sporomorphs (suc, pers. com. 1999). instead, pleistocene continental deposits (san lorenzo cycle) from the neighbouring ssaannttaarrccaannggeelloo basin offer a rich palynological documentation (bertini in sabato et al., in press). here the pollen record evidenced repeated alternations of open landscapes, dominated by steppe taxa such as artemisia and ephedra, and forests (mostly quercus) throughout the late early pleistocene. detailed palynological analyses of the upper part of the succession are in progress. the palynological analysis of both the santarcangelo and montalbano jonico sections are expected to permit marine-continental correlations during a key moment of the pleistocene. preliminary pollen data (capraro in massari et al., 2001) from the marine vvaallllee ddii mmaanncchhee section, about 150 km south of montalbano jonico, in the crotone area, are in agreement with those from santarcangelo. in central italy, the main changes in the palaeoflora and vegetation detected in the ccoollllee ccuurrttii and cceessii fluvio-lacustrine deposits (bertini, 2000), occurred between 0.9 and 0.6-0.7 ma (ficcarelli et al., 1997; coltorti et al., 1998), which is approximately the same time span covered by the santarcangelo record. the two successions reveal a progressive increase in aridity, as well as a progressive decrease in temperature, which is associated to the middle pleistocene shift from the 41 to 100 ka cyclicity in the milankovitch orbital record (bertini, 2000). during the successive open vegetation phases (glacials), chenopodiaceae and artemisia progressively increase, whereas cyperaceae decline. forest phases are first dominated by tsuga, then by abies plus picea and, finally, pinus; but these forests show no significant expansion of broad-leaved deciduous elements. palynological, sedimentological, and taphonomic evidence reveal the occurrence of several hiatuses in the early parts of the interglacials. these hiatuses were considered the palaeoenvironmental response to climatic changes affecting local lithological and geomorphological settings (karst) (bertini, 2000). the same trend observed at colle curti and cesi for tsuga, with peak of abundance during the jaramillo subchron, was also observed at ffoorrnnaaccii ddii rraanniiccaa (ravazzi et al., in press), in northern italy. at c. curti, tsuga reaches another peak, before its final decline, in the post-jaramillo inverse polarity interval. in the ppiiaanniiccoo--sseelllleerree continental succession, near fornaci di ranica, tsuga, as well as pterocarya, carya, and cedrus, are lacking at about 779 ± 13 ka, which is the date of a tephra included in the middle part of the succession (pinti et al., 2001). a much younger age, correlative with mis 5, 7 or 9, was previously suggested for this succession, on the basis of the geological setting and macroflora studies (moscariello et al., 2000). the previously mentioned climatic gradients, which characterized the mediterranean area at least since the neogene, account for the major expansion of herbs and reduced presence of relatively moister arboreal taxa in southern sites than in northern ones. tsuga is less abundant in the south, as testified by the pollen records from monte san giorgio, santarcangelo and llaa ppiinneettaa (isernia) which, taken as a whole, extend in time from the upper part of the early pleistocene to the beginning of the middle pleistocene. the available pollen data (suc & bessais, 1990; bertini et al., 1998) 25early to middle pleistocene changes ... shows that ever since the neogene this taxon has never been an important element of the forests at the latitude of sicily. at vvaalllloo ddii ddiiaannoo (southern italy) tsuga is virtually absent from 650 to 450 ka, whereas carya is constantly present, and pterocarya is sporadic. two main climatic oscillations were recognized and correlated with the glacial–interglacial cycles mis 16 to 13. as at santarcangelo the glacial intervals are characterized by high concentrations of herbaceous and steppe pollen, while the interglacial intervals are dominated by arboreal pollen. the lacustrine succession of aacceerrnnoo, southern italy, was correlated with isotopic stages 9 and 8 because of the presence of the lower white trachytic tuff (wtt) marker horizon which is dated 297 ka (munno et al., 2001). pollen analyses confirmed an interglacial-glacial cycle. interglacial conditions are indicated by a phase of oak forest expansion, while glacial conditions are marked by a sharp drop in all arboreal taxa, as well as by the simultaneous spread of herbaceous and steppe elements. here tsuga and carya are absent. 66.. ddiissccuussssiioonn the selected pollen data contribute substantially to the reconstruction of the lower and middle pleistocene landscapes in italy because they permit a direct comparison of the main palaeonvironmental (e.g. climatic and tectonic) events, at both global and local scale, with significant floristic and vegetation changes. they also address some key stratigraphic questions relevant to this time interval. 6.1. the ppb, the tiberian boundary, and the pliopleistocene range of taxodiaceae the ppb, located at the base of the marls overlying sapropel marker bed ‘e’ in the vrica section, corresponds to the beginning of a glacial period, as attested to by the spread of herbaceous and steppe vegetation after a long period of relatively homogenous, warm conditions (interglacial) (e.g. combourieu-nebout et al., 1990). in the semaforo-vrica composite section, on the other hand, the glacial-interglacial cycling starts 350 m below marker bed “e” (e.g. combourieu-nebout, 1995). therefore this event is not an unequivocal climatic signal. g/i cycles seem to set off limited change in the composition of flora associations after 2.46 ma. they must therefore be distinct. artemisia progressively gained importance in the open vegetation communities of glacial intervals, whereas warm-temperate taxa prevailed on subtropical taxa, which progressively disappeared, in forest associations during interglacials. continental sites lack most of the stratigraphical information available in marine settings. therefore, the glacial event near marker bed “e” at vrica may be a useful reference for identifying the ppb only when it is associated to the palaeomagnetic record. in fact, in the fluviolacustrine uuppppeerr vvaallddaarrnnoo basin (central italy), the recognition of the split olduvai (zijderveld et al., 1991) permitted the same resolution of marine sediments in calibrating the pollen assemblage zones to climate zonation, as well as in correlating mammal fauna biochronology with marine biostratigraphy (albianelli et al., 2002). the changes in vegetation, in particular, closely matched the climatic fluctuations, which were recorded by oxygen isotopic stages. in particular, near the ppb, an 89 % peak of herbs (glacial) follows a warm-and humid phase dominated by forest taxa (interglacial). in the past, some italian palynologists placed the ppb in correspondence to the disappearance (or better the dramatic fall) of taxodiaceae. lona et al. (1969; 1971) observed the sudden disappearance of taxodium pollen just after an acme phase in the lacustrine ppiieettrraaffiittttaa succession and called this event the “ tiberian boundary”. later on, the tiberian boundary was also recognized in the marine section of stirone about 10 meters below the level where papani & pelosio (1963) found arctica islandica (and where the ppb was placed). lona et al. (1969) and lona & bertoldi (1972) correlated this event with the beginning of the calabrian and with the ppb, pointing out the delay in the appearance of the northern marine guests. in 1977 the recovery of a. islandica specimens (pelosio & raffi, 1977) at the top of the “calcarenite” of the stirone section permitted a repositioning of the ppb. iaccarino (1996) argued that the plio-pleistocene transition occurs about 3 m below the base of the “calcarenite”, in correspondence to a downward-shift (mutti pers. com. in capotondi, 1992). these new data cleared the discrepancy between the arrival of the northern marine guests and the disappearance of the taxodiaceae, and confirmed the position of the tiberian boundary (and of the ppb). bertoldi (1977) recognized the tiberian boundary at the marker bed in the marine section of le castella. in the upper valdarno, a strong decrease in taxodium type pollen after an acme phase was observed close to the ppb (bertini, in press), as well as in pietrafitta and stirone. nevertheless, it is important to stress that the recurrence of the episodes of sudden fall in the pollen percentage of taxodiaceae during the upper part of the late pliocene does not make these events an unequivocal signal. moreover, taxodiaceae survive the ppb in many italian sites (e.g. bucha et al., 1975; bertolanimarchetti et al. , 1979; fusco, 1996; ravazzi & rossignol-strick, 1995; combourieu-nebout, 1993; 1995; bertini, 2001). this prevents an exact location of this limit, especially in short and discontinuous successions without the support of marine stratigraphy or timediagnostic elements; the latter remark was also made by lona & bertoldi (1972). the climatic requirements and geographic distribution of some extant taxodiaceae, which are shown in table i, can explain why different components of this family disappeared during the late pliocene and pleistocene in the mediterranean area (see also the interpretations of lona, 1963; lona et al., 1971; lona & bertoldi, 1972; bertolani-marchetti, 1978). in the italian pollen record, taxodiaceae are mainly represented by sciadopitys, taxodium type (which includes taxodium cf. distichium and glyptostrobus) and sequoia type (which includes sequoiadendron giganteum, sequoia sempervirens, metasequoia, cunninghamia and cryptomeria). both taxodium type and sequoia type include different genera with similar pollen morphology which prevents their specifical identification at the optical microscope. taxodiaceae were among the most important components of the zanclean and early 26 a. bertini piacenzian thermophilous forests. starting from the late piacenzian, and especially during the gelasian, after the start of g/i cycles, taxodiaceae considerably declined. the analysis of the sections selected permit the tracking of their spatial and temporal distribution in italy during the late pliocene and pleistocene (fig. 3). in the stirone and lamone successions, taxodium type is quite well represented, whereas sequoia type is scattered. at lamone, the former reaches 11.2 % in abundance in the santernian, and 4.6 % in the emilian. aside from leffe, taxodium type is absent during the emilian; it occurs at low percentages only in the lower part of cycle m, which was correlated with isotopic stages 51/50 or 53/52 by ravazzi & rossignol-strick (1995). at pietrafitta, as mentioned above, taxodiaceae (taxodium type, principally) are supposed to disappear at the ppb (lona et al., 1969), but this section lacks a precise chronostratigraphic reference. taxodiaceae are absent along the whole colle curti and cesi record (i.e. from about the upper part of c1r.2r subchron on). in the south, the dominant taxodiaceae at vrica is sequoia type, and its occurrence is testified until about 1.3 ma; at monte san giorgio they are sporadic between 1.23 and 1.095 ma. at santarcangelo, taxodiaceae are sparsely present only in the basal part of the succession. they are absent in the younger sites of isernia, vallo di diano (here sparse grains of taxodiaceae were interpreted as probably reworked elements), and acerno. the analysis of the vegetation assemblages and of their spatial distribution, together with the geological and sedimentological features of the deposits, evidenced a predominant climatic control on the taxodiaceae disappearance. edaphic and depositional factors played a subordinate role, which explains their survival as relicts (or in previous times phases of particular wide spread) in swamp environments, predominantly with taxodium type (e.g. in the tiberino or upper valdarno basins), or close to slopes (e.g. at crotone, close to the sila), mostly with sequoia type. the taxodiaceae stratigraphical range shows that their disappearance cannot be considered as an isochronous and sudden event matching exactly the ppb. it is therefore impossible to use such event (i.e. the tiberian boundary) to cross-correlate italian successions. using the tiberian boundary to establish widescale correlations resulted incorrect (lona, 1971) [see, for instance, the correlation of the tiberian boundary with the reuverian/pretiglian transition of the netherlands (zagwijng, 1975). the latter in fact is correlatable with the piacenzian/gelasian boundary (at ca 2.6 ma) and not with the ppb (at ca 1.8 ma), on the basis of chronostratigraphical considerations]. 6.2. the disappearance of subtropical to warm temperate/temperate taxa during the neogene and the pleistocene, the progressive decrease of temperature in italy, as well as the change in amount and distribution of precipitations, caused not only the already mentioned gradual disappearance of taxodiaceae, but also that of many other taxa with present day tropical to subtropical, or even extraeuropean warm-temperate/temperate range. some of them, such as cathaya, tsuga, cedrus, carya, pterocarya, liquidambar, survive for a while as relicts under microclimatic and/or edaphic conditions, before becoming thoroughly extinct. ccaatthhaayyaa is a pinaceae which now lives at various altitudes, from less than 300 m to over 1800 m a.s.l. (liu et al., 1997), only in a restricted area of northern china (wang, 1961; liu et al., 1997). the climatic requirements of cathaya identified by faquette et al. (1998a, b) are shown in table i, although this taxon probably has a wider potentiality of occurrence. cathaya shows repeated phases of expansion during the middle (e.g. at stirone; bertini, 2001) and late (e.g. at vrica; combourieu-nebout & vergnaudgrazzini, 1991) pliocene, when it became one of most important components of the mesophilous forests, remplacing taxodiaceae which characterized the zanclean thermophilous forests. cathaya progressively declined during the early pleistocene (along with pinus haploxylon type), while at the same time tsuga shows successive peaks in abundance. nowadays ttuussggaa occurs with 14 species in temperate zones of the northern hemisphere (north america, china, japan and himalaya), where it grows both alone and in association with deciduous elements. it is more tolerant than any other pinaceae to the shade, but it is also the less resistant to drought; in fact, it requires at least 1000 mm of annual precipitation. the aridity was an important limiting factor also in the past distribution and expansion of tsuga; in fact, as already discussed in paragraph 5, it has never been a major component of the vegetation in southern sites. in northern and central italy, tsuga expanded repeatedly since the early pleistocene, especially close to the jaramillo interval; the ranica, upper valdarno, cesi and colle curti samples clearly attest this. in the cesi and colle curti successions, the disappearance of tsuga, during the lower part of the brunhes chron, followed repeated phases of peak abundance between the jaramillo and the overlain c1r.1r subchron. bertini (2000) related this to the shift in global aridity. in the netherlands and at tenaghi philippon iii (macedonia, greece), tsuga shows a similar trend during the same time-interval (zagwijn, 1963; zagwijn & de jong, 1984; van der wiel & wijmstra, 1987). these data confirm the global effects of the mid-pleistocene climate transition at ca 0.9 ma (ruddiman et al., 1989; raymo et al., 1997). in the pollen diagrams, tsuga is often associated to cceeddrruuss to form the so called “tsugacedrus complex “ (e.g. bertoldi, 1995). today cedrus has a discontinuous range restricted to the montane or high montane areas between latitudes 30-40° n in three main separated regions in northern africa and southern asia. according to combourieu-nebout et al. (2000) its climatic requirements are 4 to 10 °c of ta, and 500 to 2000 mm of pa whereas fauquette et al. (1998a) propose a larger range (tab. i). because of its greater tolerance, cedrus lasted longer than tsuga (tab. i), though at generally lower percentages in the late early pleistocene records (e.g. cesi, la pineta and vallo di diano). cedrus is absent only at pianico-sellere and acerno. together with the earlier coniferous forest taxa, many subtropical to warm temperate deciduous taxa, typical of the warm mixed forests, progressively disappear following climatic gradients; some of the disappeared taxa live today in the eastern mediterranean. among the juglandacee, engelhardia, carya and pterocarya progressively disappeared from the pleistocene records. among the numerous pliocene and early pleistocene 27early to middle pleistocene changes ... 28 a. bertini f ig . 3 g e n e ra l s ch e m e o f ve g e ta tio n a n d c lim a te in i ta ly d u ri n g t h e la te l a te p lio ce n e a n d t h e m id d le p le is to ce n e . t h e m a in f lo ri st ic e ve n ts d e te ct e d in t h e s u cc e ss io n s a re s h o w n o n t h e r ig h t. genera of hamamelidaceae, embolathera, distylium, parrotiopsis, parrotia persica, and liquidambar disappeared one after another. the climatic requirements of some of these taxa are reported in table i. zelkova, a genus of ulmaceae, a family also including ulmus and celtis, represents a typical example of lazarus taxon. it was widespread during early and middle pleistocene, with variable abundances. it then survived in the eemian during forest phases and finally disappeared from central italy at about 31 ka (follieri et al., 1986; 1988). no other records testified its presence later than this time in italy until it was discovered in a relict station in sicily (di pasquale et al., 1992). 6.3. vegetation and climatic history during the early and middle pleistocene the early pleistocene pollen assemblages originated from a thorough restructuring of the neogene palaeonvironmental settings. the changes in temperature and precipitation following the maximum expansion of the arctic ice at 2.6 ma, as well as the new topography resulting from the rise of apennines caused the already mentioned progressive disappearance of tropical and subtropical forest taxa, a spread of both altitudinal arboreal taxa and herbs, and the creation of new competition patterns (fig. 3). the effects of the climatic modifications at the transition to the middle pleistocene gave rise to new major changes in the floristic and vegetal assemblages, which progressively attained a modern aspect. the eeaarrllyy pplleeiissttoocceennee is a time when open vegetation (arid and cool to cold climate conditions) and forest (humid and warm-temperate climate conditions) alternated, reflecting g/i fluctuations. the open vegetation assemblages include a large amount of steppe taxa, among which artemisia and ephedra, and sometimes also thermophilous taxa, such as cistus and phlomis fruticosa. the warm temperate forest assemblages include deciduous taxa, such as quercus, carya, carpinus, pterocarya, ulmus and zelkova. in northern italy, g/i cycles are marked by alternations of coniferous forests (especially formed by picea, with minor abundance of cedrus and tsuga) and deciduous forests (especially formed by carya, quercus, carpinus, pterocarya,) which translate relatively humid and cool to cold /humid warm temperate fluctuations. during the mmiiddddllee pplleeiissttoocceennee, the climate keeps alternating, and vegetation accordingly. the southern italian sites show alternations of artemisia (plus ephedra) steppes and temperate to warm-temperate deciduous forests. nonetheless, a generalized drop in temperature in both steppe and forest phases is indicated by changes in the floristic assemblages. for example, hippophaë rhamnoides expanded during the steppe phases, whereas thermophilous taxa, such as cistus and phlomis fruticosa, disappeared. the most thermophilous arboreal taxa progressively declined during the forested phases in accordance with climatic gradients (e.g. parrotia persica, carya, pterocarya and liquidambar). this is in agreement with the marine oxygen isotopic records, and the so called mid-pleistocene climate transition. 6.4. the palynological record from other italian sites palynological studies were carried out in many other sites, which were not included here because of their controversial stratigraphic position. the palynological content of three cores (ve-i, ve-i bis, ve-ii), collected from the holocene upper pliocene succession (cnr 1971; favero et al., 1973) of the venise area, at the northern end of the adriatic sea, in a foreland wedged between the eastern southern alps and the apennine chain, has been analysed by mullenders et al. (1996), who proposed to place the plio-pleistocene boundary at about 900 m and the tiberian boundary at about 820 m giving rise to an evident conflict. more recently kent et al. (2002) made an integrated magneto-bio-cyclostratigraphical study ena29early to middle pleistocene changes ... tab. i climatic indications yielded by selected taxa, and their present geographic distribution (from fauquette et al. 1998 a, b). pa: total annual precipitation; ta: mean annual temperature, tc: mean temperature of the coldest month, tw: mean temperature of the warmest month. the reader should refer to thompson et al. (1999) for additional information on climatic parameters. in this paper one can find alternative observations to fauquette et al..’s (1998 a, b) data, especially about sequoia sempervirens. ttaaxxaa ppaa ((mmmm ttaa ((°°cc)) ttcc ((°°cc)) ttww ((°°cc)) mmooddeerrnn ddiissttrriibbuuttiioonn engelhardia 800-2000 15-25 10-20 25-35 mexico, se asia, india, south china, taiwan, malaysia dystilium 800-2000 15-25 10-20 25-35 se asia, china, indonesy parrotia persica 300-1500 14-20 4-8 24-35 iran parrotiopsis 300-1000 7-13 -7-3 17-24 afghanistan, pakistan, india metasequoia 800-1600 10-20 0-10 20-30 china sciadopitys 1000-2500 5-15 -5-5 15-25 japan sequoia sempervirens 1200-2500 15-18 5-15 10-25 california sequoiadendron giganteum 900-1500 8-15 0,5-11 9-26 california taxodium distichium 1100-2400 16-25 5-20 25-30 se usa cathaya 1000-1600 10-20 5-10 15-30 north china liquidambar 1000-1600 10-23 0-18 20-30 north america, mexico, east asia and turkey, japon tsuga 1000-2000 0-12 -10-6 5-15 north america; japon, china, himalaya phlomis fruticosa 400-800 15-20 5-15 20-30 east mediterranean, sicily, middle east cedrus 500-1500 7-18 -1-11 18-28 northern africa and southern asia cedrus 750-1250 8-13 1-5 17-23 bling the reconstruction of the pleistocene history of sea-level changes in the venice region, in a 950 meterdeep drill core, named vveenniiccee--11 which corresponds to the composite section of the two cores ve-i and ve-i bis. kent et al.’s (2002) study permits the detection of the brunhes and upper matuyama chrons (not older than 1.7 ma) from the top of the core to 727.8 m, and from 727.8 m at least to the unconformity at 813 m, respectively. the interpretation of the succession from the break to the base of the measured section is debated. according to kent et al. (2002) the lower matuyama might extend from 813 to 887.2 m, with a hiatus cutting out at least the whole olduvai subchron (including the ppb). in this case, the matuayama/gauss boundary (at 2.58 ma) would occur at 887.2 m. alternatively, the normal polarity interval extending from 887.2 m downwards could correspond to an extremely long reunion subchron (2.14-2.15 ma) section. in spite of its above mentioned hiatus from the upper pliocene to the lower calabrian, venice-i, appears to be a significant succession to document the major lower and middle pleistocene floristic and vegetational changes in a prevalently marine environment of northern italy. the accurate revision of the palyological record (e.g. not all the recognized taxa are shown in the palynological diagrams, sporae are included in the pollen sum) made by mullenders et al. (1996) needs to be included in an adequate stratigraphical framework. such an integration has been tempted (luca capraro, 2003: pers. com.; massari et al., submitted). on the basis of kent et al.’s (2002) stratigraphical evidence, i supposed that mullenders et al.’s (1996) location of the ppb and of the tiberian boundary must be rejected. in fact, the tiberian boundary would fall below the unconformity at 813 m, i.e. in the matuyama reverse polarity interval, at least at 1.95 ma. the taxodium acme event (value up to 20%) used by mullenders et al. (1996) to define the tiberian boundary could correspond to one of the repeated climatic fluctuations which occur between 2.6 and 1.95 ma. in the succession from 950 to 820 m, the sparse occurrence of taxodium (2.2%, 14% and 0.8%), as well as the absence of repeated changes in the palynological assemblages (mullenders et al., 1996) which match the g/i cycles possibly suggest a younger age as well as a shorter overall extent of this portion (i.e. it would be the only occurrence of the reunion) than in the case of an occurrence of the gauss/matuyama boundary. the absence of significant changes near the top of the supposed gauss/matuyama boundary, where the first glacial phases start, at 2.6 ma, apparently supports this hypothesis. taxodium is almost completely absent from the pleistocene section of the sequence, with only a virtually occurrence of 0.2% and 0.6% at 561 m and 453.65 m, respectively. cathaya is not included in the floristic taxa, but it might not have been distinguished, at least in the pliocene interval, from the pinus haploxylon type, which is present up to 518 m. tsuga shows important acme phases throughout the upper matuayama. just above the highest occurrence of the large gephyrocapsa (kent et al., 2002) tsuga strongly decreases to show an isolate peak in the lower part of the brunhes (close to mis 18; kent et al., 2002). mullenders et al. (1996) recognized the first cold phase (“cryomère”) in the section from the so-called veneziano” boundary, just under the base of the brunhes, up to 576 m. the absence of evidence of previous cold phases (e.g. those corresponding to mis 22) in the palynological record is perplexing. furthermore, drops in the abundances of many taxa, such as cedrus, carya, zelkova, pterocarya, also occur before this boundary. later on, occurrences generally maintain very low (only pterocarya and zelkova show significant expansions). the ccoommppiiaannoo continental basin is located in northern italy (val di taro). pollen analyses were carried out in 6 main short sections by bertoldi (1995). in the lower portion of the outcrops sciadopitys reaches 19.4 %, followed by taxodium type (at 7.4%). moving upwards in the sequence, tsuga, cedrus, pinus haploxylon s.s. dominate the assemblages, whereas carya and pterocarya are scanty and sporadic. in the upper beds, all these taxa are missing. on the basis of this paleobotanical evidence, and in particular of the occurrence and disappearance of taxodium type, bertoldi (1995) referred the lower part of the compiano succession to the plio-pleistocene transition, and dated the overlying part of the sequence to the early and middle pleistocene. tsuga, pinus haploxylon type, cedrus, carya, pterocarya and zelkova also occur in the continental sediments of the gguubbbbiioo (perugia) and lleeoonneessssaa (rieti) basins (central italy), at 425 m and 900 m above sea level, respectively (lona & ricciardi, 1961a; ricciardi, 1965). zelkova is also reported in the mmeerrccuurree basin (southern italy), at 500 m above sea level, while tsuga, pinus haploxylon type and cedrus are missing (lona & ricciardi, 1961b); here, rare pollen grains of carya and pterocarya are regarded as reworked elements. in the light of this palynological evidence, the gubbio and leonessa deposits seem older than the mercure succession, which in turn seems to correlate with the previously described cesi sequence (bertini, 2000). unfortunately, the different latitude and altitude of the latter four continental sites, added to the already mentioned absence of an ascertained time reference, make any interpretation and attempted correlation very doubtful. lacking a well-defined palynostratigraphical framework for the early and middle pleistocene, integrated by time-diagnostic elements, correlations based solely on ecobiostratigraphical events, including last occurrences of specific key taxa, are hazardous. nevertheless, this summary singled out several key-sections in northern, central and southern italy with well calibrated major floristic and vegetational events. these can represent significant reference sections provided that geographical and edaphic factors are duly inspected. 77.. ccoonncclluussiioonn this paper aimed at showing the power of the pollen record in paleoenvironmental reconstructions and stratigraphical research, especially associated to mighty time-diagnostic implements such as tephras, magnetoand/or bio-magnetostratigraphy. this is the basis for high resolution studies and reliable correlations. the sites selected here delineate the following 30 a. bertini history of the italian early to middle pleistocene flora and climate: the unsuitable climatic conditions of this time progressively depleted the flora. in the early pleistocene, the g/i cycles caused the disappearance of extreme thermophilous taxa which are prevalently distributed in subtropical to warm temperate habitats today. the transition to the middle pleistocene was marked by a drop in the temperature and by a change in the dominant ciclicity; the effects on the flora were thus amplified. taxodiaceae, cathaya (plus pinus haploxylon type), tsuga, cedrus, carya, pterocarya, along with other taxa, progressively disappeared throughout the pleistocene. climatic gradients linked to the latitude, altitude, physiography of the sites justify their different calendar of extinction: a precise chronological reference for all these events thus is mandatory to establish reliable correlations with other such records in northern europe as well as in other mediterranean areas. changes in vegetation, also linked to g/i cycles, have been detected in both the early and middle pleistocene. glacials are generally marked by a dominance of herbaceous taxa indicative of steppe-like conditions. nevertheless, herbs never became important components of the landscape in the northern sites; on the contrary, coniferous forests dominated. interglacials are indicated by the expansion of mesophilous deciduous trees. middle pleistocene g/i cycles were characterized by lower temperatures, which caused the disappearance of extreme thermophilous taxa. on this basis we can distinguish between early pleistocene “warm’ steppes and middle pleistocene “cold’ steppes. the early pleistocene is characterized by short alternations of xeric-cool-temperate phases (or only cooltemperate phases with irrelevant decreases in humidity, in the north) (glacials) and warm moist phases (interglacials) with a predominance of 41 ka cycles. long alternations of xeric cool to cold phases (glacials) and humid warm temperate phases (interglacials) with a predominance of 100 ka cycles characterized the middle pleistocene. the selection of reference sections is indispensable to correlate sites with a controversial stratigraphical position. the information provided by the selected sections form an indispensable reference for most reliable climate quantifications and mappings of the vegetation for the early to middle pleistocene interval. the combination of these two approaches has secured striking results in studies of neogene sites (e.g. suc et al., 1999; 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(eds), ice ages: ancient and modern, 137-152. zagwijn w.h. & jong j. de., 1984 die interglaziale von bavel und leerdam und ihre stratigraphische stellung im niederland-isschen früh-pleistozän. mededelingen geologische stichting, 3377,, 155-159. zijderveld j.d.a., hilgen f.j., langereis c.g., verhallen p.j.j.m. & zachariasse w.j., 1991 integrated magnetostratigraphy and biostratigraphy of the upper pliocene lower pleistocene from the monte singa and crotone areas in calabria, italy. earth planet. sci. lett., 110077, 697-714. 36 amq 22 gruger esimpaginazione def prova 1 available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 26 (2), 2013, 101-109 the pollen record of the 190 m core fersina 2, an entirely late-glacial sediment sequence in the adige valley at trento (ne italy). eberhard grüger 1, giulio morteani 2 1) dep. palynology & climate dynamics, albrecht von-haller institute plant science, georg-august-univ. of göttingen, germany 2 gmain 1, 84424 isen, germany . corresponding author: e. grüger <egruege@gwdg.de> abstract: pollen analysis of samples taken from the core of the water well fersina 2 (adige valley, prov. trento, ne italy) did not reveal any indication of an interglacial or holocene age of the uppermost 190 m in the sediment sequence deposited in the over-deepened adige river valley. the sediment sequence dates entirely from late-glacial times. four radiocarbon ages of pieces of wood indicate that about 165 m of the upper part of the profile are of younger dryas age. the lower part of the sequence dates from the allerød or bølling/allerød and a preceding cold phase, probably the oldest dryas. accordingly the deposition of the sequence took about 2500 or 3500 years and was completed long before the onset of the neolithic. our results are in excellent agreement with findings in other formerly glaciated alpine valleys (e.g. the traun, salzach and enns valleys in the northern alps). the final depth of the fersina 2 well is 190 m. it is very likely that the sediment sequence found below this level in the nearby 423 m deep fersina 1 well was also deposited after the deglaciation of the adige valley at the end of the last glacial period. key words: trentino, adige valley, fersina, younger dryas, stratigraphy, pollen analysis 1. introduction a fairly large number of pollen studies are available on the late-glacial and holocene vegetational development in the italian alps and the apennine mountains (e.g. vescovi et al., 2010; drescher-schneider, 2009; ravazzi, 2007; ravazzi et al., 2007; vescovi et al., 2007; filippi et al., 2007; ravazzi et al., 2006; pini, 2002; grüger, 1968; beug, 1964; etc.). these studies can help to date a series of pollen-bearing sediment samples from the 190 m deep water well fersina 2 drilled in the city area of trento (north-eastern italy). the location of the coring site on the bottom of the adige river valley at an elevation of only about 200 m, the remarkable length of the core, and the fact that the sediment is lacustrine all combine to promise information about the development of the vegetation of the trentino (southern alps) since the deglaciation of the adige valley at the end of the würmian glacial period. the results of the pollen study are presented below. regional geology and sedimentology of the core sediments are from fuganti et al. (1998, 2001). tab. 1 shows how the late-glacial biozones (based on biological phenomena) correlate with grip zones (based on greenland ice core events). this system is increasingly used in more recent scientific publications on northern italy. 2. geographical situation, pollen source area and sedimentary environment almost all of the modern catchment area of the adige and its tributaries (more than 10,000 km2) was glaciated during the maximum of the last glacial period (würmian). when the ice margin of the adige valley glacier retreated to the north from its southernmost position south of trento, a vast lake formed in the overdeepened adige valley (e.g. venzo, 1957). it must have been many km long, and it was probably as wide as the fig. 1 a) position of the lake garda area (black square) in italy. b) lake garda area. sediment core sites mentioned in the text marked by encircled dots, elevations given in meters above mean sea level. the broken line delimits the southern border of the würmian moraines south of lake garda. c) the alluvial fans of the trento area (from venzo 1957, changed), f = profile fersina 2 (this paper), p3 = site studied by venzo (1957). the non-shaded part of the inset marks the more or less flat, late-glacial bottom of the narrow adige valley. adige valley. this lake was still in existence when the younger dryas glaciers which did no longer reach the trento area melted down. huge amounts of melt water were available at that time to transport an enormous sediment load to the south and thus to fill up the overdeepened adige valley. in the trento area much of the infill material was contributed by the torrente fersina. this river, originating in the dolomites, enters the adige valley in the area of the city of trento and cascades down from a hanging valley about 200 m above the bottom of the modern adige valley (fig. 1) forming an alluvial fan there on which part of the older quarters of the city of trento and the fersina coring site are located. the combined sediment input of fersina and adige caused an extraordinarily high sedimentation rate and thus a rapid filling-up of the vast lake basin. the stratigraphy of the fersina cores (fig. 2) shows that predominantly clay and silt, but also fine sand and some sandy gravel, were deposited in the trento area. in the study area the adige valley is bordered to the west and east by mountain ranges rising to more than 2000 m. the area is consequently characterized by a much diversified altitudinal zonation of the vegetation, including treeless alpine meadows. the pollen produced in these varied vegetational zones was brought to the coring site probably predominantly by the wind. nonanemogamous species, even components of the bankside vegetation, had almost no chance to be represented in the sediment as the later coring site was probably about 1 km away from the nearest lake shore. additional pollen was transported to the trento lake basin by the rivers from more distant regions, contemporary pollen and possibly also pollen reworked from older sediment well upstream from the coring site. an unknown quantity of the pollen floating on or suspended in the lake water was carried away with the excessive river water. due to the great sedimentation rate (see below), complete mixing of the annual input of sediment might have been impossible. if so, the pollen contents even of different subsamples of the same annual layer might differ to some degree. from the above, it follows that the sedimentary environment of the fersina core was so different from that of smaller lake basins and peat bogs the usual source of information on the former vegetation and of its changes that a direct comparison of pollen values – especially of less frequent taxa must not be done. the main features of the vegetational development, however, will remain visible despite loss of pollen and inadequate size of samples. 3. sampling the well fersina 2 was drilled (percussion drill) in march/april 1997 in the southern part of trento near the present-day confluence of the rivers fersina and adige (46° 02’ 50” n, 11° 07’ 08.5” e; 190.6 m a.s.l.). the drilling was ended at a depth of 190 m when the aquifer was reached. a continuous casing was used during drilling to prevent collapse of the well walls and hence incorporation of younger sediment in the samples. therefore disturbances of the sedimentary and pollen record can be excluded. the samples were labelled according to the sampling interval of about 1 meter. a grüger e., morteani g. 102 table 1 correlation of late-glacial grip zones and swiss biozones according ammann et al., 2012 and van raden et al., 2012. table 2 calibration of the conventional radiocarbon dates from trento and wiggle matching of the fersina 2 dates. 103 f ig . 3 p o lle n d ia g ra m . t h e p o lle n v a lu e s a re s h o w n a s p e rc e n ta g e s o f th e p o lle n t o ta l. p o lle n s u m , p o lle n c o n ce n tr a tio n s, a n d a m o u n ts o f st o m a ta a re g iv e n a s n u m b e rs . n o te t h a t th e s ca le s ch a n g e i n o rd e r to s a ve s p a ce . d o ts d e n o te w h e re t h e p e rc e n ta g e v a lu e s a re ≤ 0 .3 o r w h e re o n ly o n e s to m a o f p in u s w a s fo u n d . r a d io ca rb o n d a te d le ve ls : i: 1 1 5 0 0 ± 1 5 6 c a l a b p ; ii : 1 1 6 5 3 ± 2 1 4 c a l a b p ; ii i: 1 2 1 0 9 ± 2 2 3 c a l a b p ; iv : 1 2 3 7 9 ± 1 6 6 c a l a b p . f ig . 2 s tr a tig ra p h y o f th e c o re s f e rs in a 1 a n d f e rs in a 2 , d e si g n b y a . f u g a n ti, ch a n g e d b y g . m o rt e a n i a n d c . p re in fa lk , d e p th s o f p o lle n sa m p le s a d d e d b y e . g rü g e r. …. fersina 2, an entirely late-glacial sediment sequence ….. sediment sample called, e. g., “37 m” represents the sediment found between 36 and 37 m depth. in total, 100 irregularly shaped lumps of sediment (100 to 200 cm3) were available for pollen analysis. all samples consist of white silt, clay, and fine sand. the well fersina 1, located some 36 m from fersina 2, was drilled in the same year. this drilling was stopped at 423 m without yet having reached bedrock. no pollen samples are available from this well, but the huge thickness of the sediment clearly shows that the adige river valley was over-deepened at least up to trento. fig. 2 shows the stratigraphy of the cores fersina 1 and 2 (fuganti et al., 2001 and own data). 4. radiocarbon dating / wiggle matching four pieces of wood found in the fersina 2 sediment were radiocarbon dated (table 2). the resulting conventional and calibrated radiocarbon ages were published by fuganti et al. (1998). since an improved calibration data set is now available (reimer et al., 2009), the radiocarbon ages from trento were re-calibrated using the calpal software (weninger & jöris, 2008). following a proposal of m. geyh, the former director of the hannover radiocarbon laboratory, the radiocarbon ages of the four pieces of wood were submitted to “wiggle matching”, kindly carried out by b. weninger (university of cologne). to accomplish wiggle matching, a calendric distance of 10 ± 50 calyrs was assumed for the two younger pieces of wood, and a distance of 90 ± 50 calyrs for the two older pieces. thus fitted into the calcurve, radiocarbon ages of 11,603 ± 146 cal a bp (final year) and of 12,281 ± 142 cal a bp (final year) result for the two pairs of pieces of wood. 5. pollen analysis 5.1. pollen preparation and pollen diagram the aliquots for pollen analysis (2.3 to 14 cm3, average 5.2 cm3) were taken in the laboratory from the inner part of the cored material to prevent contamination with recent pollen. the standard mode of sample preparation, with hcl and hf and wet ultrasonic sieving as the final step (width of mashes 8 µm), did not produce a pollen concentration sufficient for a reliable pollen count. treatment with hcl and naoh, followed by flotation with sodium tungstate solution (na2wo4, d = 2.05) as described by eisele et al. (1994), but without acetolysis, proved to be more effective. to allow the calculation of pollen concentrations, one lycopodium spore tablet (containing 10,679 ± 191 spores) was added to each pollen sample at the beginning of the treatment (stockmarr, 1971). the pollen counts range from 204 to 1225 (mean 592) grains per sample. four samples only contained fewer than 484 pollen grains. the complete results of pollen analysis are presented in fig. 3 and table 3. supplementary data are available at doi:10.1594/pangaea.793027. the pollen diagram was drawn using panplot (diepenbroek et al., 2001), with graphical details being improved with microsoft paint. all given pollen values are percentages of the pollen total. 5.2. the pollen record the salient feature of the pollen diagram (fig. 3) is the dominance of the pinus sylvestris type in all pollen spectra (88.4 to 34.3 %, mean 71.5 %). next in frequency are the pinus cembra type (8.8 to 1.3 %, mean 5.1 %) and betula (1.5 to 18.3 %, mean 5.2%). all other tree pollen types were found less frequently; indeed, their pollen values rarely exceed 1%. tree species with such low pollen values – among them the thermophilous tree species – can hardly have been of any importance in the area or were even missing when the profile fersina 2 was deposited. but pine trees occurred in the area, as evidenced by pinus stomata being present in 14 out of 17 samples. temporary increases of the nap (nonarboreal pollen) values combined with a frequent 104 grüger e., morteani g. table 3 rare pollen and spore types (numbers). occurrence of pollen grains of shade intolerant species indicate former changes of the vegetation. details will be discussed in the following. the two lowermost samples (185 and 186 m) are comprised of clay. they show the highest nap values recorded in the pollen diagram (21.3 and 39%, respectively). up to 12.7 % of the pollen total was produced by the shade intolerant genus artemisia. artemisia species never occur in a forest. the same is true for the chenopodiaceae (9.8 and 5.3 %). the percentages of the indeterminable pollen types (indeterminata), certainly not pollen of woody species, are high (11.1 and 6.6 %). the diversity of nonarboreal pollen types (nap) was never greater than at the time of deposition of these two samples. among the woody taxa, the pollen frequencies of the pioneer shrub hippophae (7.4 and 13.3 %), of juniperus (0.4 and 0.6 %), and of two ephedra -pollen types (up to 1 %) are of special interest. these shrubs are sunlight-demanding and cannot thrive in the shade of trees. on the other hand, no other sample of the profile contains more pollen of picea (2.0 and 2.2 %), corylus (0.8 and 1.0 % not much for this shrub!), and ulmus (0.4 and 0.6 %) than these two samples. pollen of quercus and tilia was not found. pollen concentration is medium in sample 185 m, but very low in sample 186 m (see fig. 3). a low pollen concentration is caused either by the absence of pollen-producing plants or by a high rate of sedimentation. never during the deposition of the fersina 2 sediment was the vegetation around the coring site more open and the climatic conditions less favourable than at the time when the clay below the sandy gravel (i.e. below 184 m, fig. 2) was deposited. the region was not forested, but was probably not treeless. the pine values are lower than further up in the profiles, but – together with the occurrence of one stoma of a pine needle – possibly sufficiently high to assume the presence of some pine trees in the area. the comparatively high values of picea, ulmus and corylus are somewhat confounding. it is possible that these pollen grains come from the reworking of older sediments. the presence of the mentioned species in the area is unlikely in view of the reconstructed situation. the pollen spectra of the samples 172 and 171 m, taken in a layer of sandy gravel (fig. 2), indicate warm conditions during the time of their sedimentation. high pine pollen sums (91.3 and 89.3 %), the very low nap values (1.9 and 3.3 %), and the only occasional occurrence of pollen grains of shade intolerant taxa indicate that the region was forested when the two samples were deposited. pollen of the thermophilous trees quercus and ulmus is rare. on the other hand, tilia cordata-type pollen is in no sample more frequent than in sample 171 m (1.8 %). the pollen spectrum of sample 161 m, taken from sandy gravel, shows with 5.2 % artemisia, 3.9 % chenopodiaceae, 8.2 % indeterminata, and a nap sum of 21.5 % pointing to a return to climatic conditions similar to those prevailing when the clay of samples 185 m and 186 m was deposited. evidently the forest had disappeared again. only a few tree specimens may have been left in the area. it is remarkable that in this sample the prequaternary reworked sporomorphs reach their absolute maximum, probably a result of intensive erosion of prequaternary pollen-bearing sediments by the rivers fersina and adige. consequently the pollen concentration is low. with only 396 pollen grains per 1 cm3 of sediment it is the lowest concentration value in our series of samples. the samples 154 m (sandy gravel) (fig. 2), 139 and 124 m (silty clay with sandy levels) document, with nap values around 10 % and the occurrence of shade intolerant taxa, climatic conditions that were similar, although probably somewhat less severe, than those indicated by the pollen preserved in the lower part of the profile, below and above the 171 and 172 m samples (see above). pieces of well-preserved wood prove the presence of pinus cembra (sample 130 m) and of pinus mugo/sylvestris (sample 139 m) in the region. the two pieces of wood were radiocarbon dated by wiggle matching to 12,280 ± 142 cal a (table 2). after the deposition of sample 124 m, the ecological situation changed markedly. starting with sample 114 m, the nap values are distinctly lower than before (mostly less than 5 %). pinus stomata are more frequent. pollen of hippophae and artemisia, although present in all but one (hippophae) and three (artemisia) of the 17 studied samples, is rare. ephedra pollen was found in two of the nine pollen samples above the 124 m level only (3 pollen grains). these changed conditions lasted throughout all the time represented by the rest of the profile. birch was probably present. pollen of thermophilous deciduous trees like quercus, ulmus, and tilia is recorded as before, with variable, but low, values. a few specimens of these trees only can have grown in the vicinity if their pollen grains did not come with the wind from more distant sites or was reworked. in a layer of sand two pieces of juniperus wood (samples 32 and 33 m), but no pollen grains of this shrub, were found. the radiocarbon age of the two pieces of wood is 11,603 ± 146 cal a bp (wiggle matching, table 2). 6. discussion 6.1 the age of the sediment of the fersina 2 well – general remarks the deposition of the lacustrine sediment studied can have started only after the retreat of the adige glacier to the north beyond the trento area. the sediment met by the fersina 1 and 2 wells can therefore be of late -glacial up to postglacial age only. the following dating relies on pollen analyses and on four radiocarbon dates. pollen analytical dating is based on the fact that most european tree species and important groups of herbs are anemogamous. because such plants let the wind disperse their pollen grains, pollen diagrams of large areas are usually similar to each other. therefore, a new profile can usually be dated by comparing the composition of its pollen assemblages and their changes with that of other not-toodistant, reliably dated pollen sequences. the sampling sites next to trento with pollen dia 105 …. fersina 2, an entirely late-glacial sediment sequence ….. grams suitable for a comparison with the fersina pollen data are mentioned below and are shown in fig. 1. they are not the only pollen diagrams from this area, but the others are not detailed enough to be useful for our purpose, e.g. the preliminary diagram (with only seven pollen curves) from a peat profile at isera near rovereto, about 20 km south of trento in the adige valley (calderoni et al., 1996) and kofler’s diagrams from bondone and lago delle buse (kofler, 1994). 6.1.1 the postglacial three detailed pollen analytical studies from the trento area are available to answer the question whether the fersina 2 profile can be of postglacial age. two of the studied profiles come from filled-up lakes (grüger, 1968), namely bondone, at 1550 m, only 8 km southwest of trento, and fiavè, at 654 m, about 25 km off trento, west of bondone. the third profile is from the extant lake of lavarone, at 1115 m, about 20 km southeast of trento (filippi et al., 2007). the most remarkable event during the early postglacial was the expansion of the thermophilous deciduous tree genera quercus, ulmus, tilia, fraxinus, and acer and of corylus during the preboreal (11,500 to 10,200 cal a bp), the first biozone of the postglacial. although the center of the distribution of these species lies in the lower altitudinal zones, the sum of their pollen values rises at fiavè (at 654 m) from low values to 30%, at lavarone (1115 m) to 25 %, and to around 10% further up at bondone (1550 m). it should be expected that the contemporary sedimentation in the adige valley produced, at least in the uppermost part of the profile fersina 2, values not less than those found at fiavè and lavarone; but the fersina pollen data are mostly much lower. in 11 of the 17 studied samples the pollen values of the thermophilous deciduous tree genera are ≤ 1%, and in a further four samples between 1 and 2%. only in samples 124 and 139 m are higher percentages reached (4.3 and 3.5 %, respectively, mainly oak pollen). these two samples can, however, not be of postglacial age if the results of the radiocarbon dating are accepted. also no hints can be found in the fersina 2 pollen diagram of later important vegetational events like the immigration and spreading of fagus and abies trees, which were present in the area from about 8000 cal a bp. the pollen curve of fagus, an important constituent of the montane forests, climbs to more than 40 % of the tree pollen sum at lavarone and to more than 10 % at bondone, and abies reaches more than 15 % at both localities (j. grüger, unpublished, counts available under http://doi.pangaea.de/10.1594/pangaea.763901). in the fersina 2 samples, not a single pollen grain of fagus, and only one pollen grain of abies have been found. evidently no part of the fersina 2 pollen diagram shows characteristics of the holocene forest development. no section of the profile fersina 2, the uppermost sandy gravel included, can be of postglacial age. the sediment of the entire fersina 2 profile must have been deposited during late-glacial times, with the only exception of the colluvial material forming the modern surface in the area, a layer being too thin to be shown in the stratigraphical scheme (fig. 2). 6.1.2 the late-glacial the younger dryas, the final part of the last glacial period, started around 12,700 cal a bp; it ended when the holocene vegetation began to develop in the study area about 11,600 to 11,500 cal a bp (vescovi et al., 2007). the radiocarbon ages of the four pieces of pine and juniper wood found in the fersina 2 sediment (table 2) prove that these tree species had been growing in the study area during younger dryas times. being well preserved, these pieces of wood were probably not repeatedly transported, exposed, and temporarily embedded, so they most likely date the sediment in which they were discovered. if so, at least the part of the core between 32 and 139 m must be of younger dryas age. the pollen spectra of the samples 3, 14, and 24 m do not distinctly differ from those of proven younger dryas age below. apparently a younger dryas type of vegetation was still present in the trento area when the uppermost 30 m of sediment (mainly sandy gravel) were deposited so that this sediment can hardly be of postglacial age. the radiocarbon age of the upper piece of wood (table 2) allows, however, a deposition time of a few decades only so that a huge annual sedimentation rate must be assumed. to explain this one must not assume a climatic change, it is sufficient to consider the special conditions of sedimentation on an alluvial fan. rivers usually shift over their alluvial fans. where they flow they can accumulate huge amounts of sediment in a short time. the coarseness of the uppermost sediment indicates that at the time of the deposition of this material the river fersina flowed and dropped its sediment load where the fersina core was taken. thus the thickness of the uppermost layer of sandy gravel cannot be used as an argument against a younger dryas age of this part of the profile as proposed by the pollen data. younger dryas vegetation is documented in the profile downwards to sample 161 m. the next older pollen spectra (171 and 172 m) indicate distinctly warmer, though not interglacial, conditions. these spectra can only be of allerød age. samples 185 and 186 m, the oldest samples of the fersina 2 profile, contain a pollen flora which indicates cold conditions. this climatically unfavourable period can either be the colder middle part of the allerød or one of the preceding cold phases of the late-glacial, namely the older dryas or the oldest dryas. the allerød is a tripartite interstadial, that is, it has a climatically less favourable phase sandwiched between warmer phases at its beginning and before its end. the cooler phase, called the gerzensee oscillation, lasted a few hundred years only (250 years according to greenland ice core isotope data, grip zone gi-1b, björk et al., 1998, or 400 years according to swiss lake sediment isotope data, schwander et al., 2000). although distinct in the oxygen isotope records, only a weak reaction of the vegetation is recorded by the pollen data. in switzerland (sites gerzensee and leysin; wick, 2000) and western germany (site meerfelder maar; stebich, 1999), a decrease in the importance of betula pollen (percentages as well as concentrations and influx) is the most indicative reaction. the more 106 grüger e., morteani g. thermophilous vegetation growing at that time in tuscany, 340 km south of trento (lago dell’accesa, drescher-schneider et al., 2006), however, responded distinctly to the changed conditions as is clearly indicated by lowered quercus and higher nap (mainly poaceae) values, and by a series of minor changes of a few further pollen curves (accesa ii oscillation). the pollen diagrams from the trento area, bondone, fiavè (grüger, 1968) and lavarone (filippi et al., 2007) do not show any indication of a climatic deterioration during the allerød, probably as no plant species requiring higher temperatures were present at that height and were at best rare at lower altitudes. the pollen diagram of saltarino sotto only, a low-lying site (194 m) 75 km southwest of trento near lake garda (grüger, 1968), shows changes in the allerød time samples (320 cm and 325 cm) which most likely are the expression of a cooler climate. betula values diminished by about 9 %, while nap (about 10 %, mainly poaceae and artemisia) and juniper values (>1 % instead of 0.4 % before and 0.8 % after the oscillation) increased. the rise of the qm (quercetum mixtum) curve – here mainly oak – stopped, but the rise continued when the climatic conditions improved, so that qm values of 30% were reached at the end of the allerød. the qm values dropped to a much lower level during the following younger dryas stadial. considering the weak response of the vegetation around saltarino sotto to the gerzensee oscillation, it appears unlikely that the change from forest (samples 171 and 172 m) to an open type of vegetation (185 and 186 m) at trento was caused by this climatic deterioration. consequently, part of the lower sandy gravel (fig. 2) must represent the entire allerød, the bølling possibly included, interstadials during which the annual sedimentation rate was apparently much reduced compared to that of younger dryas time. the two lowermost samples of core fersina 2 (185 and 186 m) must date from either the older or the oldest dryas. it is not possible to decide which of these two stadial phases is the one truly represented. fig. 2 shows that the lowermost clay of the profile fersina 2 can be correlated with the uppermost part of a thick sequence of rather homogeneous fine grained lacustrine sediment in the 423 m long profile fersina 1. as no drastic changes in the composition of the sediments are apparent, it is likely that the lower part of the profile fersina 1 is also of late-glacial age. older sediment is not likely to have escaped erosion by the water running off under the large, melting adige glacier, especially in the middle of the valley where the coring site is located. pre-würmian sediment can be preserved only in rare sheltered positions. 7. conclusions in contrast to that supposed so far, the fersina 2 profile does not reach back in time to the last interglacial. instead, it was deposited totally during the youngest part of the late-glacial, i.e., during upper palaeolithic times. the sedimentation of fersina 2 (190 m of clay, sand and gravel) took only about 2500 to 3500 years, and it was finished before the holocene (= postglacial) development of species-rich forests began. this happened in the trento area around 11,500 cal a bp, in archaeological terms, during mesolithic times, several thousand years before the neolithic culture reached the trento area. the ancient neolithic units at the archaeological sites riparo gaban and ala le corone in trento date from 6749-6993 and 6551-6892 cal a bp, respectively (angelucci & bassetti, 2009). that the entire fersina 2 sediment sequence was deposited during the late-glacial is in agreement with the situation in the eastern alps, where the filling up of glacially over-deepened valleys was completed before the postglacial started (van husen, 1979). the results of the fersina 2 study necessitate reconsidering the dating of the 193 m long profile p3, taken about 5 km north of fersina 2 in the industrial zone of trento at an elevation of 190 m (venzo, 1957, 1979). venzo stated that “the stratigraphical and sedimentological data testify to the existence of an ancient lacustrine basin immediately following the last glaciation in the adige river valley (i dati stratigrafici e sedimentologici della serie testimoniano l’esistenza nella zona di trento di un antico bacino lacustre di grande estensione, immediatamente successivo al ritiro dell’ultima glaciazione)“. venzo called the basin also a “bacino lacustre post-würmiano”, “a post-glacial lacustrine basin”, definitely referring to the proper postglacial (=holocene). venzo totally disregarded the preceding more than 15,000-year-long late-glacial period, during which the adige valley of the trento area was ice free, a necessary condition of the deposition of the fersina 1 and 2 sediment. as venzo’s site p3 (venzo 1957) must have been located in the area of the same late-glacial lake as the fersina 2 site, the p3 profile must also be of late-glacial age. this is even in agreement with venzo’s note cited above on the formation of the lake basin. the same applies to the 30 m deep well via giuseppe verdi in the center of trento, 3 km north of the fersina 1 and 2 wells (fuganti et al., 1998). it may be surprising that in the core of this well, 11 m below the modern surface, a piece of wood with a radiocarbon age of only 4710 ± 80 cal a bp (table 2) was found in lateglacial sediment. this discrepancy can be explained if it is assumed that the meandering rivers adige and fersina cut channels into the late-glacial sediment which were later filled with material from the surroundings containing wood of (in this case) subboreal age. the number of pollen types found in the fersina 2 samples is low when compared with the younger dryas pollen samples of the other mentioned profiles. this difference results from the fact that their younger dryas samples contain the pollen rain of many years (e.g. about 14 and about 20 years, respectively, in the profiles saltarino sotto and bondone) whereas the fersina 2 samples contain, due to the huge annual sedimentation rate, less than one year’s pollen precipitation only. as pollen analytical dating is mostly based on common pollen types, the fersina 2 pollen data are sufficient to date the core, they but are not detailed enough to discuss problems of the north italian vegetation history. acknowledgements we thank andrea fuganti (trento) very much for 107 …. fersina 2, an entirely late-glacial sediment sequence ….. the permission to study the samples of the fersina 2 well, and for discussions about the morphology of the trento area and the influence of the river fersina on the sedimentation processes in the adige valley. we owe the wiggle matching to bernhard weninger and mebus a. geyh. ruth drescher-schneider, angelika kleinmann, werner kofler, josef merkt, and roberta pini helped by sending reprints, by contributing information, and by discussing special problems. the layout of fig. 2 is the work of christine preinfalk. gisela and wolfgang tambour touched up the original drafts of the figures and converted them into the necessary electronic files. dirk van husen patiently taught the first author the principles of sedimentation in alpine valleys. dean hansen improved the english. many thanks to all of them! references ammann b., van leeuwen j.f.n., van der knaap w.o., lischke h., heiri o, tinner w. 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(1957) ricerche sulla serie lacustre e fluviale attraversata de pozzi trivellati nella zona industriale di trento. giornale di geologia, 26, 173 -188. venzo g.a. (1979) glaziale übertiefung und postglaziale talverschüttung im etschtal im raum von trient (italien). eiszeitalter und gegenwart, 29, 115-121. vescovi e., kaltenrieder p., tinner w. (2010) lateglacial and holocene vegetation history of pavullo nel frignano (northern appennines, italy). review of palaeobotany and palynology, 160, 32-45. vescovi e., ravazzi c., arpenti e., finsinger w., pini r., valsecchi v., wick l., ammann b., tinner w. (2007) interactions between climate and vegetation during the lateglacial period as recorded by lake and mire sediment archives in northern italy and southern switzerland. quaternary science reviews, 26, 1650-1669. weninger b., jöris, o. (2008) a 14c age calibration curve for the last 60 ka: the greenland-hulu u/th timescale and its impact on understanding the middle to upper paleolithic transition in western eurasia. journal of human evolution, 55, 772-781. wick l. (2000) vegetational response to climatic changes recorded in swiss late-glacial lake sediments. palaeogeography, palaeoclimatology, palaeoecology, 159, 231-250. 109 …. fersina 2, an entirely late-glacial sediment sequence ….. ms. received: april 05, 2013 final text received: jun 25, 2013 amq short notes 26_2 zerboni divito monegato available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 25 (2), 2012, xvii xviii report on the alpine quaternary workshop (intimate & inqua-ceclap) obergurgl, austria, 3-7 october 2013 giovanni monegato1, karin a. koinig 2, christoph spötl 3, oliver heiri 4 1 cnristituto di geoscienze e georisorse, torino, italy 2 institute of geology, university of innsbruck, innsbruck, austria 3 institute of ecology, university of innsbruck, innsbruck, austria 4 institute of plant sciences and oeschger centre for climate change research, bern, swiss corresponding author: g. monegato <g.monegato@csg.to.cnr.it > abstract: we provide a short report on the alpine quaternary workshop, held tirol region (a). the discussion was aimed at illustrating suitable proxy records for correlations in the alpine region for the time window 8 to 60 ka. keywords: intimate, inqua, late pleistocene, alps. on 3-7 october 2013 the alpine quaternary workshop took place in obergurgl (a) in the central alps of tyrol and discussed climate change in the alpine region over the last 60,000 years. 32 scientists, postdocs and phd students from 7 different countries attended the workshop. this was a merger of two initiatives, intimate-cost (http://costes0907.geoenvi.org/), focusing on the discussion and compilation of climate proxy records from the greater alpine region for the time window 8 to 60 ka and to make them eventually available to the paleoclimate and modelling community in an easy-to-access database, and inquaceclap (circumalpine events and correlations during the late pleistocene), focusing on the correlation on late pleistocene records in the alps. fig. 1 workshop participants at the rotmoos type locality monegato g. et al. xviii two workshops held in 2012 preceded the obergurgl meeting: intimate working group 2 workshop “climate records in the austrian and swiss sectors of the alpine region”, which took place in bludenz (a), and the ceclap workshop “the lgm in the alps”, which took place in udine (i). the 2013 workshop encompassed proxy records from the entire alps and their forelands, and the goal was to draw from as many sources of paleo-information as possible. a large part of the meeting was therefore spent on presentations by all attendants in order to get to know each other’s research topics, which included lake sediments, cave deposits, fluvial and glacial systems as well as paleobiological and geoarcheological aspects. the discussion routinely expanded into the late evening with small groups sitting together and discussing data. during the final session two groups were formed, one focused on the time frame 18-8 ka, the other concentrating on the older period from ca. 60-18 ka. the aim was to identify key topics of paleoclimate research in the alps for the near future. which are the most urgent questions? which methodologies are needed to advance this research field? which archives are unrepresented? in addition to the plenary activities and presentation sessions, field trips were organized in order to promote onsite exchange of ideas on a range of topics concerning the last 60 ka of environmental change in the alps. a midconference fieldtrip, held on october 4, led to the rotmoos mire, the type locality of the mid-holocene rotmoos oscillations, recorded by the local vegetation history in the palustrine deposit. a first post-workshop excursion took place on october 7 at the baumkirchen pit, stratotype of the boundary between the middle and upper würmian in the alps (lead by christoph spötl, sam barrett and reinhard starnberger). this excursion provided fresh insights based on new drillings, their analysis and chronological data. this excursion had a late afternoon stop for an overview of slightly older paleolake and slope sediments in the unterangerberg region, about 50 km downstream in the inn valley. a following two-day field trip (led by jürgen reitner) examined field evidence, based partly on detailed geological maps, of the lgm glacier advance and late glacial oscillations in tributary valleys of the lower inn valley and discussed ice-flow reconstructions and valley overdeepening. in this field trip, the lower würmian successions of hopfgarten were also visited and discussed. the joint days both at obergurgl and in the field triggered intense discussion and fostered the exchange of new ideas and concepts. the participants agreed to continue and expand these activities and plans are to convene again in 2014 to focus on the western alpine region. fig. 2 the lacustrine succession of the baumkirchen clay pit (middle würmian, inn valley) was visited after the conference. ms. received: october 18, 2013 final text received: october 18, 2013 intimate & inqua-ceclap, 3-7 october 2013 xix imp.mozzi ssttrraattiiggrraapphhyy,, ppaallaaeeooppeeddoollooggyy aanndd ppaallyynnoollooggyy ooff llaattee pplleeiissttoocceennee aanndd hhoolloocceennee ddeeppoossiittss iinn tthhee llaannddwwaarrdd sseeccttoorr ooff tthhee llaaggoooonn ooff vveennii-ccee ((iittaallyy)),, iinn rreellaattiioonn ttoo tthhee ccaarraannttoo lleevveell ppaaoolloo mmoozzzzii11,, ccllaauuddiioo bbiinnii22,, lluucciiaa zziilloocccchhii22,, rroobbeerrttoo bbeeccaattttiinnii33,, mmaarrttaa mmaarriioottttii lliippppii33 1 dipartimento di geografia, università di padova, via del santo 26, padova, italy e-mail: paolo.mozzi@unipd.it 2 dipartimento di scienze ambientali, università di venezia, 2137 dorsoduro, venezia , italy. e-mail: bini@unive.it 3 dipartimento di biologia vegetale, università di firenze, via la pira 4, firenze, italy e-mail: mariotti@unifi.it abstract the present investigation brings new stratigraphic, palaeopedological and palynological data deriving from the study of 4 cores, bored to a maximum depth of 15 m in the central sector of the lagoon of venice, along the inner shores, between the mouth of the dese river and porto marghera. in agreement with the general stratigraphy known from previous studies, the lowermost deposits in the cores are fluvial, radiocarbon dated to 21,000 – 18,000 bp. the correlation to the stratigraphic framework of the central veneto plain shows that they belong to the late pleistocene fluvial sedimentary system of the brenta river, the bassano megafan. the pollen record of this alluvium is characterized by typical hydrophilous plants (typha, potamogeton, nymphaea...), which are referred to swampy environments during the last glacial maximum and the late glacial. the compact level known as caranto, located at the top of the fluvial sediments at a depth of some metres from the ground surface, has been recognized as consisting of a set of pedogenetic calcic and gley b and c horizons. this palaeosol formed on the alluvial plain of the distal reaches of the bassano megafan, in the time span comprised between the deactivation of fluvial processes, which took place after 14,500 bp and probably before the beginning of the holocene, and the lagoon transgression. as the latter apparently interested the study area only in post roman times, pedogenesis could act for 8000 – 12,000 years. the definition of the pedogenetic nature of the weathering features is based on macro and micromorphological observations, associated with physico-chemical analyses. the palynological analysis shows that the caranto level is characterized by a very low pollen content. the late holocene lagoonal deposits which cover the caranto palaeosol have dominant subtidal / intertidal mud flat and salt marsh facies, within a context of varying water salinity probably related to river inputs. the presence of a slightly pedogenized level developed in a salt marsh environment, indicates a hiatus in the deposition of the lagoonal sediments. two radiocarbon datings of the organic o horizons of this soil in two cores show that this discontinuity is of medieval age. furthermore, they provide a reliable chronostratigraphic support to the determination of the recent relative sea level rise. this latter has been estimated 2.3 m since 1055 – 954 cal bp to present day in porto marghera, enirisorse area, and 1.1 m since 640 – 592 cal bp to present day in porto marghera fusina, abibes area. riassunto nel corso di questa ricerca sono stati studiati dal punto di vista stratigrafico, paleopedologico e palinologico le carote provenienti da 4 sondaggi ubicati al margine interno del settore centrale della laguna di venezia, tra la foce del f. dese e porto marghera, per una profondità massima di 15 m dal piano campagna. in accordo col contesto stratigrafico generale già definito in numerosi studi precedenti, i depositi lagunari olocenici ricoprono qui, con spessore esiguo, una serie fluviale datata 21.000 – 18.000 bp. il record pollinico di questi sedimenti è caratterizzato da piante idrofile (typha, potamogeton, nymphaea ...), tipiche di ambienti palustri riferibili all’ultimo pleniglaciale e al tardiglaciale. inquadrando i depositi fluviali nell’ambito della pianura veneta centrale, si evince che il sistema sedimentario attivo nell’area di studio era quello tardopleistocenico del brenta (megafan di bassano), in aggradazione fino al tardiglaciale. al tetto dei depositi alluvionali è presente il livello alterato, sovraconsolidato, con screziature e noduli carbonatici, conosciuto nell’area lagunare con il nome di “caranto”. mediante uno studio paleopedologico, e comparando i risultati con le caratteristiche dei calcisol presenti sulle superfici distali del megafan di bassano in prossimità della laguna, è stato possibile confermare la natura pedogenetica delle figure di alterazione che lo contraddistinguono. il “caranto” è stato dunque interpretato come un suolo sepolto, che si è sviluppato sui depositi di esondazione del tratto distale del megafan di bassano. l’arco temporale per la sua formazione è compreso tra la cessazione dei processi fluviali, avvenuta successivamente a 14.500 bp e, probabilmente, prima dell’inizio dell’olocene, e l’ingressione lagunare. nell’area di studio quest’ultima è attribuibile al periodo post romano, e dunque l’intervallo complessivo durante il quale la pedogenesi ha potuto agire è di 8000 – 12.000 anni. l’analisi palinologica ha mostrato che nel “caranto” il contenuto in polline ha valori estremamente bassi, probabilmente a causa della distruzione dei granuli durante la pedogenesi. i depositi lagunari indagati, riferibili all’olocene recente, presentano prevalentemente facies di fondo lagunare / piana intertidale e di palude salmastra (barena / salt marsh), con evidenza di fluttuazioni nella salinità dell’acqua, probabilmente dovute all’alterno influsso dei fiumi che sfociavano in laguna. la presenza di un livello debolmente pedogenizzato in ambiente di palude salmastra, indica l’esistenza di una lacuna stratigrafica all’interno della serie lagunare indagata. due datazioni al radiocarbonio degli orizzonti organici di questo suolo in due diverse località, indicano che tale hiatus ricade in età medievale. questi dati cronostratigrafici permettono, inoltre, di fornire una stima del recente innalzamento relativo del livello marino, pari a 2.3 m da 1055 – 954 cal bp al presente nell’area enirisorse di porto marghera, e 1.1 m dal 640 – 592 cal bp al presente nell’area abibes di porto marghera fusina. key words: venice, last glacial maximum, late glacial, palaeosol, palynology, alluvial plain, lagoon. parole chiave: venezia, last glacial maximum, tardiglaciale, paleosuolo, palinologia, pianura alluvionale, laguna. il quaternario italian journal of quaternary sciences 1166(1bis), 2003, 193-210 194 p. mozzi et al. 11.. iinnttrroodduuccttiioonn the lagoon-and-barrier sedimentary system of the lagoon of venice (fig. 1) is the result of a long-term history of delicate equilibrium between sea and land, that is, between coastal and fluvial processes. during the holocene, the sea level has been continuously rising, as a result of the combined effect of the post glacial eustatic sea level rise and local land subsidence. meanwhile, the piave and brenta rivers have been delivering large volumes of sediments to the adriatic sea. these materials, due to redistribution along the coast, have been providing the sands for the upbuilding of the barrier islands. on the other hand, these large alpine rivers repeatedly had their mouths within the lagoon itself, together with smaller rivers such as the musone, marzenego, dese and sile. in fig. 1a, it is possible to perceive how a further southwestern expansion of the piave sedimentary system, in connection with the sile system, would imply the infilling of the northern lagoon, as much as a progradation of the brenta system would bring about a forced regression in the southern lagoon. the only area in which there has been no important fluvial activity is in the central lagoon, where the distal fringes of the late pleistocene bassano megafan and nervesa megafan pro parte, reach the lagoon shores. in the underground, these late pleistocene continental deposits represent the bed on which the lagoonand-barrier sediments lie (fig. 1b). rivers freely choose their way to the lagoon just until the beginning of the second millenium a.d., when human control on the hydrographic network became progressively stricter. in fact, rivers brought about a lowering of the salinity near their mouths, because of the mixing of fluvial fresh-water with salty sea water. they also enhanced sedimentation, as they delivered alluvial sediments into the lagoon. both these tendencies were regarded as negative, and strongly contrasted by the venetians, for both sanitary (prevention of malaria) and economic (navigation in the lagoon) reasons. between the 11th and fig. 1a geomorphological sketch of the central veneto plain (modified from bondesan et al., 2002). 1. nervesa megafan (late pleistocene, holocene); 2. montebelluna megafan (late pleistocene); 3. bassano megafan (late pleistocene); 4. brenta alluvial plain (holocene); 5. monticano, cevada and meschio fans (holocene); 6. livenza alluvial plain (holocene); 7. sile, dese and zero alluvial plain (holocene); 8. musone alluvial plain (holocene); 9. piedmont fans (holocene); 10. littoral sandy deposits (holocene); 11. moraines (late pleistocene); 12. fluvial erosive scarps; 13. hills and mountains; 14. natural (a) and artificial (b) hydrography; 15. core location; 16. location of the geological cross section of fig. 1b. fig. 1b geological cross section (modified from broglio et al., 1987). 1. alluvial deposits of the bassano megafan (late pleistocene); 2. lagoonal deposits (holocene); 3. littoral deposits (holocene). a) b) 17th century a.d., the main rivers were artificially driven out of the lagoon by the venice republic, and only the minor watercourses were let in. in order to investigate the complex relations between the alluvial and lagoon sedimentary systems during the upper pleistocene and holocene, the inner shores of the central lagoon of venice, between the mouth of the dese river and porto marghera, have been chosen as a study area. particular attention has been devoted to the firm, mottled horizon locally known as caranto, widespread in the underground of the central lagoon, with the aim of understanding its genesis and evaluating its stratigraphic importance. 22.. tthhee ggeeoollooggiiccaall ffrraammeewwoorrkk the holocene lagoon-and-barrier sedimentary complex of the lagoon of venice started forming most probably around 7000 6000 bp (bortolami et al., 1977); the oldest radiocarbon datings of organic materials at the base of the lagoonal deposits are 7210±40 bp (depth of ca. 4.00 m below mean sea level) in the island of s. erasmo (schiozzi & brambati, 2000), 5090±100 bp (depth of 5.95 m below mean sea level) in the northern lagoon (serandrei barbero et al., 2001), 4670±70 bp in the underground of piazza s. marco, venice (depth of 5.80 m below mean sea level) (serandrei barbero et al., 2001). in general, in the central lagoon the deposits have an average thickness of around 5 m, progressively thinning towards the mainland (fig. 1b), but the scours of the tidal channels can be more than 10 m deep (alberotanza et al., 1977; mcclennen et al., 1997). in the underground of the city of venice, the lagoonal deposits, consisting of both silty clay sediments and sandy infillings of tidal channels, have a thickness of between 2 and 6 m. the sandy littoral deposits of the barrier islands, which separate the lagoon of venice from the adriatic sea, reach a maximum thickness of ca. 15 m (gatto, 1980; tosi, 1994). the accomodation space of the lagoon-and-barrier deposits has been provided by the coupled post glacial eustatic sea level rise and local land subsidence, that together constitute the relative sea level rise. considering the last 6000 years, the sea level changes derived from coral dating in tahiti (bard et al., 1996) and speleothemes dating in the thyrrhenian sea (alessio et al., 1997) are consistent in indicating an eustatic sea level rise between 2 and 3 m. these trends, based on a reliable record for the last 12,000 years (antonioli & silenzi, 1998), may be taken as an indication also for the northern adriatic sea. the average subsidence rate in the lagoon of venice during the holocene has been estimated to be ca. 1.3 mm/year (bortolami et al., 1977; bortolami et al., 1984; serandrei barbero et al., 1997, serandrei barbero et al., 2001). altogether, this would suggest a theoretical relative sea level rise for the lagoon of venice of ca. 10 m during the last 6000 years (8 m due to land subsidence and 2 m to eustatic sea rise). available levelling measurements for the 1908–1930 period give a much lower subsidence rate of about 0.5 mm/year in the lagoon of venice (gatto & carbognin, 1981; carbognin et al., 1984; carbognin & tosi, 2003). these measurements were carried out before the peak of man-induced subsidence, related to over-pumping of underground water for industrial use in porto marghera during the mid20th century, and are thus indicative of the natural trend. based on this latter subsidence rate, the theoretical relative sea level rise for the lagoon of venice during the last 6000 years, before human impact, would only be ca. 5 m (3 m due to land subsidence and 2 m to eustatic sea rise). for comparison, we recall that the relative sea level rise since 6000 195stratigraphy, palaeopedology and palynology of late pleistocene ... bp has been estimated to be about 4 m in the lagoon of caorle, 30 km to the east of the lagoon of venice, and 8 9 m in the lagoon of marano, 15 km farther east (galassi & marocco, 1999). these differences may be due to different rates of land subsidence in different locations and time intervals. the lagoon-and-barrier sediments lie on top of late pleistocene alluvium (fig. 1b). in venice, the overall thickness of the fluvial deposits posterior to the last interglacial (marine isotopic stage 5e) is about 60 m (mullenders et al., 1996; kent et al., 2002). the topmost, radiocarbon dated, peat levels indicate that fluvial sedimentation was still active in the lagoon area during the last glacial maximum (bortolami, et al., 1977; tosi, 1994; serandrei barbero et. al., 2001); the latter is here intended as the period extended from about 22,000 to 15,000 bp, within the marine isotopic stage 2, during which the last maximum expansion of ice sheets and mountain glaciers took place in the northern emisphere (crowley & north, 1991, p. 47; orombelli & ravazzi, 1996). in the central lagoon these deposits mainly belong to the pleistocene brenta sedimentary system, which formed a megafan with the apex at the mouth of the brenta valley near bassano del grappa, elongated in a se direction (bassano megafan, fig. 1a) (mozzi, 1995; 1998; bondesan et al., 2002). the aggradation of the distal portions of this megafan was continuous until ca. 14,500 bp, after which the deactivation of the distributary system took place, due to fan-head trenching in the piedmont sector. this probably happened in response to the deglaciation of the alpine area, a crucial environmental change which occurred at the pleistocene – holocene transition. in any case, the presence of mesolithic (sauveterrian) sites at the surface in the distal bassano megafan, near the lagoon shores (broglio et al., 1987), indicates that sedimentation had already stopped by the early holocene. in the lagoon and in the mainland, these late pleistocene fluvial sediments consist of scarcely interconnected, few-metresthick, sandy channel deposits embedded in laminated, silty clay overbank deposits, with common, few-centimetres-thick peaty levels with lateral extension up to a few kilometres (favero et al., 1973; serandrei barbero et. al., 2001; iliceto et al., 2001; bondesan et al., 2002; bondesan & mozzi, 2002). at the top of the continental series is a compacted, mottled, 1 – 3 m thick level, with common millimetric to centimetric carbonatic nodules. gatto & previatello (1974) called this level a palaeosol, but they did not support this statement with any analytical or morphological assessment. it is regarded as rather continuous in the underground of the central lagoon, mantling the slightly undulated, gently southwards dipping unconformity surface positioned between the late pleistocene continental series and the overlying, mid-holocene barrier-andlagoon deposits (gatto, 1980). it is locally known as caranto, a word which was introduced in the scientific literature by the early geotechnical studies concerning the underground of venice (matteotti, 1962); the foundations of the city of venice rest on wood bearing piles which are driven in the resistant caranto. in fact, caranto is a word in venetian dialect with which peasants in the mainland traditionally indicate hard, cemented horizons, often forming few centimetres thick crusts, outcropping in the fields during tillage. soils with such horizons are 196 the typical calcisols widespread in the venetian plain, having late pleistocene, fine silty alluvial deposits as parent material (giandon et al., 2001). much palynological research has been carried out on the quaternary deposits of the lagoon of venice (bertolani marchetti, 1967; horowitz, 1967; paganelli, 1967; buurman, 1970; bandini mazzanti et al., 1974; calderoni et al., 2000). these studies evidence the occurrence of a continental environment during the glacial period, characterized by pine forests, particularly constituted by pinus sylvestris or p.mugo, and other microthermic plants. in the holocene, the area was dominated by mixed oak woods. the withdrawal of the arboreal plant pollen and the appearance of grains of hygro-hydrophytes record the development of wet environments. pollen grains which may be referred to a typical lagoon flora have been detected in most surface levels. 33.. mmeetthhooddss during this investigation the sedimentary series have been cored continuously to depths ranging between 5 and 15 m, in four different locations on the inner shores of the lagoon (fig. 1a): core pm 1, punta montiron, at the mouth of the dese river, depth 0 15 m; er 32, porto marghera, enirisorse area, depth 0 8 m; vecon 6, porto marghera, vecon area, depth 0 10 m; ab 6, porto marghera fusina, abibes area, depth 0 5 m. the deposits have been described in order to recognize the sedimentary and pedological features. 14c datings have been carried out by g. calderoni of the university of rome “la sapienza” (bondesan et al., 2002; bondesan & mozzi, 2002). radiocarbon dates have been calibrated with the calibration program calib rev 4.3, based on stuiver & reimer, 1993 (probability distribution, 1 sigma). palynological and palaeopedological analyses have been carried out just on cores pm 1, vecon 6 and ab 6, in the interval centred on the main unconformity between the continental and lagoon deposits. the sediment samples used for chemical and physical analyses have been air-dried and crushed to pass through a 2 mm sieve. standard laboratory methods have been carried out on the fraction <2mm, and included particle size distribution (clay, silt and sand content) by pipette method, organic carbon content according to walkey and black method, and ph (1:2.5 soil water ratio). cation exchange capacity (cec) and total acidity have been determined by titration after extraction with triethanolamine and bacl2 buffered at ph 8.2. total carbonates have been determined by gas-volumetric method using dietrich-fruehling calcimeter. micromorphology has been carried out on selected undisturbed samples, impregnated with resin and cut to obtain thin sections ca. 30 µm thick. description of thin sections has been carried out following bullock et al., 1985. for palynological analyses, the available sediment samples have been treated with cold hcl and hf, hot hcl and na-hexametaphosphate, sieved (250 µm), treated with hot naoh, stored in a water/glycerol solution 50% v/v. pollen percentages are calculated on the total of pollen grains and spores. 44.. ccoorreess ssttrraattiiggrraapphhyy aanndd ppaallaaeeooppeeddoollooggyy ccoorree ppmm 11 stratigraphy between 15.00 m and 12.60 m two main sand bodies, with erosive lower boundaries, are present (fig. 2). both show fining upward sequences, the lower one (14.90 ÷ 14.50 m) from medium sand to fine sand, the upper one (13.80 ÷ 12.60 m) from fine sand to sandy silt. between the two is a set of thinly laminated silt and silty sand, with a 15-cm-thick layer of silty clay at the bottom. on top of the upper sandy layer is a 10-cm-thick layer of peat, radiocarbon dated 20,630±240 bp (rome1188; bondesan et al., 2002), followed by 65 cm of silty clay which grades upwards to sandy silt. above lie a set of laminated alternances of silt and very fine sand, capped by 20 cm of silty clay. between 10.65 and 10.55 m there is another peat level, dated 18,720±200 bp (rome-1187; bondesan et al., 2002), 22,630 – 21,810 cal bp. the peat is covered by 2.25 m of clay silt, with evident millimetric planar bedding, containing common remnants of canes. three peaty layers are present within this sequence: the upper, and thicker one, at a depth of 8.55 ÷ 8.45 m, has an age of 18,200±190 bp (rome-1186; bondesan et al., 2002), 22,010 – 21,130 cal bp; these peat layers, as the others present in the core, show abrupt upper boundaries, while the lower boundaries are transitional in 2 4 cm. on top lie two thin sandy layers, separated by a clay silty loam interval between 7.80 and 7.50; the lower one shows positive grading from fine sand to very fine silty sand, the upper one consist of silty fine sand. the stratigraphic sequence is interrupted at the depth of 7.00 m, as the core has been damaged during drilling operations, and starts again at 6.00 m. between 6.00 and 4.50 m, the sediment is mainly silty; above 5.30 m, this interval is characterized by a firm consistence (pocket penetrometer test on the core give values of 3.50 kg/cm2), a massive structure, the presence of many hard carbonatic nodules several millimetres large, and abundant greyish and yellowish mottles. between 4.50 and 4.00 m is an organic rich silty loam, followed by thinly laminated, centimetric and decimetric alternances of fine sand, with varying percentages of silt and clay, and silty loam. many broken shells are present in the 4.00 – 2.30 m interval. the top 1.5 m are anthropogenic, and consist of urban garbage, as the borehole is located in an abandoned waste. see also tab.1 for details. textural and pedological analyses the uppermost samples (pm 1/1 to 5) are sandy, though in varying percentages, while the lower ones are more silty (fig. 3). all the samples examined show neutral to subalkaline reaction, and low carbonate percentage in the upper layers (samples pm 1/1 to 4); carbonate tends to disappear in the intermediate levels (samples pm 1/5-6-7), and to increase at the bottom. cation exchange capacity (cec) is medium to low, and decreases with depth; organic matter presents variable contents (range 1.5 – 6.5%) at the surface, decreasing with depth. micromorphology thin section examination of selected samples from p. mozzi et al. 197stratigraphy, palaeopedology and palynology of late pleistocene ... fig. 2 stratigraphic logs (see also tables 1, 2 and 3 for facies description and interpretation). 1. c: clay, z: silt, s: sand, g: gravel; 2. sand, silty sand; 3. silt, sandy silt, clay silt; 4. clay, silty clay; 5. organic loam; 6. peat; 7. anthropic deposits; 8. shells; 9. plant remains (leaves, canes, wood, rootlets); 10. carbonatic nodules; 11. buried soil, with horizons; 12. 14c date; 13. sample; 14. core gap; 15. tentative correlation of the top of the medieval organic horizons; 16. tentative correlation of the top of the caranto palaeosol. 198 this core indicates these prominent features. sample pm 1/7 presents a close porphyric microstructure, with high coarse/fine (c/f) ratio and few interconnected pores. blackish-brown undifferentiated organic components (undecomposed tissue fragments) are scarce. the coarse fraction consists of medium and fine sand, and coarse silt. quartz grains dominate, followed by mica flakes. the groundmass is greyish and the birefringence in the fine fraction results from small mica flakes and from randomly distributed clay domains. no calcitic features have been observed. the sample beneath (pm 1/8) is a yellowish-brown clayey-silt with greyish mottles. the microstructure is laminated, with graded subhorizontal laminae; coarser material is found at the bottom, and is constituted by fine quartz grains in a calcareous, silty groundmass. in this calcareous silt, carbonate nodules and semi-continuous crusts form in the bottom part of the layer. the samples underneath (pm 1/9, pm 1/10) present finer texture with thin laminations, alternatively oxidized (silty) and reduced (sandy), in a clayey-calcareous matrix; the thinner laminations tend to aggregate in calcareous nodules, similar to those of the above described horizon. ccoorree eerr 3322 stratigraphy between 8 and 6 m, the series is characterized by centimetric to decimetric alternances of fine sand and silt (fig. 2). the thicker sandy layer in this interval, between 7.70 and 7.40 m, is coarser (medium sand) and better sorted. from 6.00 to 4.60 m the sediment is a silty clay loam, firm, with up to 50% greyish (5y 6/1) and yellowish (2.5y 6/8) mottles, 2 – 10 mm large; between 5.45 and 4.60 m, there are up to 25% hard and soft caco3 nodules, 2 – 4 mm large. above there are 10 cm of grey (10y 5/1) silty clay, with many cuticles of canes, passing gradually (in 3 cm) to a dark grey (5y 5/2) peat (4.50 ÷ 4.05 m), dated 1095±55 bp (rome-1206), 1055 – 954 cal bp. this organic layer is covered by a 15-cm thick layer of very fine sand (abrupt boundary), which in turn lies under 30 cm of medium sand, well sorted, containing many cardium shells; the boundary between the two is erosive. on top there are more than 3-m thick anthropogenic deposits (landfill of the industrial area of porto marghera). ccoorree vveeccoonn 66 stratigraphy the lowermost sediments in the core (fig. 2), between 10.00 and 9.70 m, consist of 1 – 3 mm thick alternances of fine sand and silt, overlain by 1 m of laminated clay silt. above, between 8.70 and 6.90 m, is a rather thick layer of silty fine sand, which grades upward to sandy silt (6.90 ÷ 6.20 m), and is covered, through an abrupt boundary, by silt (6.20 ÷ 5.90 m). between 5.90 and 3.45 m the series is rather homogeneous from a grain size point of view, spanning from silty clay to silty loam, but the general characteristics differ much in the various levels. between 5.20 and 3.55 the sediments are firm (up to 4.5 kg/cm2 with the pocket penetromer), massive, stained by many yellowish and greyish mottles, with up to 7% hard caco3 nodules. underneath (5.90 ÷ 5.20 m), the sediments are grey and less firm; the same applies to the 3.55 ÷ 3.45 m interval, which in addition contains common millimetric plant remains p. mozzi et al. fig. 3 pedological analyses of core pm 1 (wood, cuticles). between 3.45 and 2.80 m the silty sand sediments contain many, partly decomposed, wood fragments and much dispersed organic matter, the latter showing a peak in the top 10 cm. the 2.80 ÷ 2.40 m layer consists of laminated silty clay. the topmost deposits are anthropogenic (landfill of the industrial area of porto marghera). see also tab. 2 for details. texture and pedological analyses the analysed portion of the core is characterized by marked variations (fig. 4). the upper sample (vecon 6/1) is a subalkaline silty clay; carbonate and organic matter contents are moderately high, and cec is moderate. underneath there are two coarser levels (samples vecon 6/2, 6/3), loamy to loamy sand, decarbonated and acid, with high organic matter content and cec. further underneath (sample vecon 6/4) a change occurs, with a marked decrease in sand content (<10%); in this subacid silty-clay level carbonates are absent, organic matter and cec are low. the samples beneath this one (vecon 6/5 to 6/12) present rather uniform characteristics. texture is clay silty, with sand contents ranging from 1% to 10%. reaction is overall subalkaline; carbonates are abundant and organic matter content is very low or absent, cec is low. the deepest sample (vecon 6/13), instead, is a subalkaline sandy loam, calcareous, with very low cec. micromorphology sample vecon 6/3 presents coarse texture with high porosity (>20%) determined by interconnected chambers and channels. the mineral fraction in the groundmass is greatly masked by abundant, reddish brown organic matter fragments (mostly roots and undecomposed tissue fragments). remnants of calcareous shells are frequent too. underneath, a layer (sample vecon 6/4) with fine texture, uniformely distributed throughout, occurs. the groundmass is prevalently silty-calcareous, with a few sand-size quartz relicts. in the top part of this layer organic fragments are still present, while in the bottom part these disappear; ferrugineous nodules and yellow mottles occur in a grey matrix. microstructure is apedal with very low porosity (total pores <5%); calcareous features are absent. the previously described layer shades off gradually in a set of fine silty, calcareous levels with a grey colour and pale yellow fine sand laminations. calcareous material in the matrix is arranged into cryptocrystalline nodules of septaria type (sample vecon 6/5, fig. 6e); some of these nodules are cut by thin fissures. at the bottom of these levels, coarser material (fine sand) forms discontinuous laminations with the finer one; the groundmass is greyish with yellowish mottles and fine fe-mn granulations, and the calcareous material is arranged in concretionary forms (sample vecon 6/6, fig. 6f), as above. ccoorree aabb 66 stratigraphy between 5.00 and 4.30 m the silty and silty clay loam contains many hard and soft carbonatic nodules, often in horizontal laminae (fig. 2); it is firm and with yellowish and greyish mottles. the overlying silty clay loam (4.30 ÷ 3.80 m) also contains few soft carbonatic 199stratigraphy, palaeopedology and palynology of late pleistocene ... fig. 4 pedological analyses of core vecon 6 nodules, but the matrix is not carbonatic. between 3.80 and 3.20 m there are centimetric alternances of silt, silty loam and loam, covered by a 40-cm thick layer of peat, the top 10 cm of which have been dated 585±50 bp (rome-1205), 640 – 592 cal bp. over the peat, between 2.80 and 2.30 m, is a clay to silty loam; partly decomposed plant remains (cuticles of canes) are commonly present in the lower 30 cm, while in the upper part some rootlets are present and the remaining organic matter is dispersed or in the form of carbonaceous flecks. see also tab. 3 for details. texture and pedological analyses the whole section is characterized by a relevant vertical variability, as evidenced by textural differences and by total carbonate and organic matter contents, ph and cec values (fig. 5). the upper sample (ab 6/1) is a fine clay silt with a neutral reaction, calcareous, with low cec and moderate organic matter content. beneath is a silty clay layer (sample ab 6/2), subacid, with medium cec and high organic matter content. the mineral fraction of the peaty layer underneath (sample ab6/3b) is a sandy loam; carbonate is absent, ph is acid, cec and % of organic matter are high. sample ab 6/4 is an acid loam, non calcareous, moderately active, with high organic matter content. the underlying samples (ab 6/5, 6/6, 6/8 and 6/7) are characterized by textures ranging from silty clayey to silty. the ph increases to subalkaline values and therefore carbonate is present with relevant concentrations (up to 40%); instead, organic matter is low (<1%), as well as cec. micromorphology sample ab 6/4 (fig. 6a) presents a moderately developed subangular blocky microstructure; total voids are 20%, with interconnected planes and channels; basic mineral components are rounded quartz grains; organic components are partly decomposed fragments of tissue, which contribute to the grey-blackish colour of the matrix. the fine fraction is fine silty with close porphyric speckled b-fabric and randomly distributed clay domains with a weak birefringence. the sample underneath (ab 6/5, fig. 6b) presents similar subangular blocky microstructure, but the soil matrix appears bleached (yellowish to greyish), and ferrugineous features are present in the form of impregnative nodules and dendritic segregations, frequently bordered by clay papules. textural pedofeatures are present in the form of fine and coarse laminations, with common fragments of terrestrial gasteropod shells. in sample ab 6/6 there are common caco3 crusts and nodules (fig. 6c). underneath, sample ab 6/8 (fig. 6d) shows apedal to very weakly developed subangular blocky microstructure, with total voids <10%; calcitic features predominate in the form of weakly laminated calcareous crusts and channel infillings. few shell fragments are present. the groundmass is rather uniform in all samples. the coarse fraction (>5 µm) consists of medium and fine sand, where quartz grains dominate, followed by mica flakes, ferrugineous segregations and organic fragments. 200 p. mozzi et al. fig. 5 pedological analyses of core ab 6 201stratigraphy, palaeopedology and palynology of late pleistocene ... fig. 6 thin sections of selected soil horizons: a) cg horizon in core ab6 (sample 4, cross polarized light xpl): speckled b-fabric, with traces of subvertical rootlets; b) 2bcg horizon in core ab 6 (sample 5, xpl): iron – manganese nodule with clay rim, in non calcareous, closed-porphyric matrix ; c) 2ckg1 horizon in core ab 6 (sample 6, plane polarized light ppl): laminated calcareous crusts; d) 2ckg2 horizon in core ab 6 (sample 8, xpl): laminae with caco3 nodules; e) 2ckg1 horizon in core vecon 6 (sample 5, xpl): septaria calcite nodule in compact matrix; f) 2ckg2 horizon in core vecon 6 (sample 6, ppl): dusty carbonatic nodules. 55.. ppaallyynnoollooggiiccaall aannaallyyssiiss ccoorree ppmm11 in this core (fig. 2, fig. 7), samples pm 1/16 and from 7 to 1 present an apf (absolute pollen frequency) ranging from 900 to 3,400 grains per gram. samples pm 1/15 8 proved palynologically quite sterile. in sample pm 1/16, the nap (herbaceous plant pollen) sharply prevails over the ap (arboreal and shrubby plant pollen). with regard to the ap, pinus pollen is the most abundant; a large part of the grains is attributable to pinus sylvestris l. or to pinus mugo turra. other microthermic species are picea, abies and betula. ephedra fragilis type is also present. elements of the oak mixed forest (such as quercus, corylus, carpinus) and hygrophilous trees are scarce. among the nap, cyperaceae dominate (37.7%), showing their highest percentage within the pm 1 core; other hygrophilous and hydrophilous plants (typha cf. latifolia, potamogeton, nymphaea) are present. gramineae are relatively abundant, followed by chenopodia-ceae and artemisia. samples pm 1/7 and pm 1/6 are characterized by very high percentages of chenopodiaceae grains, up to 47%. these noticeable values are ac-companied by significant plumbagina-ceae (cf. limonium) pollen percentages (7.8% and 6.3%). cyperaceae percentages drop. the ap are less numerous than in sample pm 1/16. samples pm 1/5 and pm 1/4 show a sharp increase of deciduous tree pollen, while pinus pollen has low percentages. quercus becomes the dominant genus among the ap, followed by corylus, carpinus betulus l. and other elements of the oak mixed forest; these plant curves show their maximum value in sample pm 1/4. fagus curve achieves a maximum in sample pm 1/5. alnus pollen is abundant, particularly in sample pm 1/5, where it is accompanied by salix. among the nap, chenopodiaceae percentages sharply fall and reach their lowest value (11%) at pm 1/4. plumbaginaceae curve follows the same trend as chenopodiaceae. cyperaceae and aquatic plants are scarce. in samples pm 1/3 and pm 1/2, the percentage of the oak mixed forest elements slowly decreases, as well as the alnus percentages. abies shows a rise in sample pm 1/2 (8.4%). among the nap, chenopodiaceae record firstly an increase and later a decrease; cyperaceae are increasingly represented. in sample pm 1/1, the ap present again an increased percentage. the oak mixed forest seems to be expanded, deciduous quercus and corylus being the best represented trees. castanea achieves its highest percentage. alnus reaches 8%. among the nap, chenopodiaceae are well represented, while cyperaceae have decreased, though their percentage remains significant. ccoorree vveeccoonn 66 the most ancient samples vecon 6/13 and vecon 6/12 present very low pollen content, especially sample vecon 6/13 (apf=100) (fig. 2, fig. 8). in sample vecon 6/12, most of the grains are referable to the nap, expecially to cichorioideae, gramineae and cyperaceae; sparganium/typha angustifolia is also present. among the ap, pinus pollen dominate; the grains are referable to some different species, among which p. sylvestris and p. mugo. samples from vecon 6/11 to vecon 6/5 result quite palynologically sterile. samples vecon 6/4, 6/3 and 6/1 are rich in grains, apf ranging from 2,300 to 16,600 grains per gram. on the contrary, sample vecon 6/2 present a low apf (200 grains per gram) and badly preserved grains. in the latter samples, ap percentage is low, suggesting a very scarce arboreal cover. however, the oak mixed forest plants are represented by different morphotypes, which are expecially numerous in sample vecon 6/1. pinus 202 p. mozzi et al. f ig . 7 p e rc e n ta g e p o lle n d ia g ra m o b ta in e d f ro m c o re p m 1 pollen is always present in low percentages. alnus and salix, with the sporadic occurrence of populus, indicate the presence of wet environments, as well as cyperaceae among the nap. cyperaceae percentage increases upwards where aquatic plants, such as callitrichaceae and potamogeton, are present too. chenopodiaceae are very abundant throughout the section, with the exception of sample vecon 6/2. plumbaginaceae and chenopodiaceae indicate the occurrence of brackish environments. ccoorree aabb 66 only samples ab 6/1, 6/2 and 6/3b present a sufficiently high pollen concentration to allow an exhaustive pollen analyses, apf ranging from 600 to 21,100 grains per gram (fig. 2, fig. 9). samples ab 6/8, 6/7, 6/6, 6/5 and 6/4 proved almost sterile. the ap percentages are very low (7 25%). consequently, we can hypothesise that the arboreal cover was almost totally absent near the sampling site. the arboreal plant grains in the list may have been longdistance transported from mountain (i.e. picea, abies) and oak mixed forests (i.e. quercus, carpinus, corylus). among the nap, chenopodiaceae pollen is the most abundant (34 39.2%). the examined morphotypes are similar to those of the salicornieae, which grow on salty soils, as well as plumbaginaceae (cf. limonium) that are also present in the samples. the percentages of these last plants, which are generally underrepresented in the spectra (heim, 1975), validate the widespread of brackish habitats. cyperaceae, which indicate moist environments, are well represented. other records significant for water habitats (juncus, typha cf. latifolia, sparganium/typha angustifolia, callitrichaceae, potamogeton) have been found especially in the lowest sample. 66.. sseeddiimmeennttaarryy eennvviirroonnmmeennttss aanndd ffaacciieess the characteristics of the lowermost sediments in core pm 1, in the interval 15.00 ÷ 5.30 m, allow their interpretation as fluvial deposits. overbank fines are dominant; the only evident channel deposits are those of the graded sandy layer between 13.80 and 12.60 m, while the thinner sand bodies most probably represent crevasse splays. the peat on top of the channel body, dated 20,630±240 bp, marks the deactivation of the channel. the presence of several peaty layers within the floodplain sequences indicates the recurrence of events of diminished sedimentation in the flood basins and the formation of marshes with prevalent organic sedimentation. the radiocarbon dates show that they formed during the last glacial maximum. sediments with similar 203stratigraphy, palaeopedology and palynology of late pleistocene ... f ig . 8 p e rc e n ta g e p o lle n d ia g ra m o b ta in e d f ro m c o re v e co n 6 facies are found in core er 32, between 8 and 6 m, and in core vecon 6, between 10 and 6 m, where a channel body is present between 8.70 and 6.90 m, covered by silty loam natural levee. all these deposits belong to the pleistocene brenta sedimentary system, which extends at the back of the central sector of the lagoon of venice (fig. 1); they represent the distal fringes of the bassano megafan, in aggradation until after 14,500 bp. geochronology is consistent with the palynological data. in fact, the sampled sediments in pm 1 and vecon 6 (samples pm 1/16, vecon 6/12), have low ap percentages, but relatively high values of pinus pollen, particularly pinus sylvestris / mugo pollen group; other plants from cold or cold-dry climate (picea, abies, betula, ephedra belonging to the e. fragilis pollen type) are also present. actually, in all the samples of the three cores, the ap percentages are generally low or very low, suggesting that the arboreal cover was always scarce, or almost totally absent, at the sampling sites. among the nap, gramineae and cyperaceae are abundant; chenopodiaceae show significant percentages. the results suggest the presence of woodlands characterized by picea, pinus sylvestris and/or p. mugo and betula, trees that today grow in mountain areas; the quercetum was poorly widespread. lacustrine or marsh habitats were frequent; xerophilous plants occurred on dry, perhaps sandy, substrates. the spectra recorded are in agreement with those of previous palynological studies carried out on pleistocene or preboreal sediments from veneto, po plain and from the central adriatic sea (bertolani marchetti, 1967; paganelli, 1967; paganelli & miola, 1991; accorsi et al., 1996; bertoldi, 1996; lowe et al., 1996; paganelli, 1996a; 1996b). between 5.30 and 4.50 m in pm 1, 6.00 and 4.60 m in er 32, 5.90 and 3.55 m in vecon 6, 5.0 and 3.80 m in ab 6 there is evidence of post depositional weathering of the alluvial deposits. the most striking features are the abundant caco3 nodules and mottling, evident both to macroand microscopic observation, and the high matrix consolidation, measured on some cores with the pocket penetrometer (tab. 1, 2, 3). all these elements are indicative of the caranto level, as described in previous literature (gatto & previatello, 1974; alberotanza et al., 1977; tosi, 1994; serandrei barbero et al., 2001). nevertheless, it is to be noted that also the calcic horizons of the silty clay soils in the mainland, developed on the late pleistocene alluvial plain in the distal reaches of the bassano megafan, at the immediate proximity of the lagoon, have similar characteristics (giandon et al., 2001); regarding the overconsolidation, the b and c horizons of these latter soils are commonly as firm as the caranto, with mean values of 3.0 4.0 kg/cm2 to the pocket penetrometer. the different horizons of the caranto level observed in the cores (fig. 2; tab. 1, 2, 3) are thus, most likely, pedogenic calcic b and c horizons as well, having the silty clay calcareous sediments of the top of the underlying fluvial sequence as the parent material. the redistribution of carbonates along the profile, due to leaching in the upper horizons and reprecipitation in the lower ones, was associated with alternating oxidizing and reducing conditions, as evidenced by the abundant mottling. the non calcareous 2bcg horizon in core ab 6, between 3.80 and 4.00, probably represent the upper horizon of the original soil profile, depleted of caco3 by vertical leaching. 204 p. mozzi et al. f ig . 9 p e rc e n ta g e p o lle n d ia g ra m o b ta in e d f ro m c o re a b 6 205stratigraphy, palaeopedology and palynology of late pleistocene ... dd eepp tthh ss aamm ppll ee tt eexx ttuu rree ss ttrr uucc ttuu rree mm uunn ssee llll mm oott ttllee ss cc aacc oo 33 cc aacc oo 33 oo .. mm .. pp llaa nntt rr eemm aaii nnss ss hhee llllss lloo ww eerr ff aacc iiee ss m # (u s d a ) (a nd p .p . t es t) cc ooll oouu rr % , c ol or , d im en si on s nn oodd uull eess % % bboo uunn ddaa rryy 1. 50 –1 .8 0 1 lo am y la m in at ed , s of t 5y 4/ 1 n o n o 8 15 n o n o a br up t la go on sa nd (0 .5 0 kg /c m 2 ) 1. 80 -1 .9 0 n o sa m pl e lo am y sa nd m as si ve , s of t 5y 4/ 1 n o n o n o n o a br up t la go on lo am (0 .5 0 kg /c m 2 ) 1. 90 -2 .3 0 2 s an dy la m in at ed , s of t 5y 4/ 1 n o n o 5 65 n o n o a br up t la go on (0 .5 0 kg /c m 2) 2. 30 -2 .7 0 3 s ilt y lo am la m in at ed , s of t 5y 4/ 1 n o n o 5 19 n o m an y, n ot la go on (0 .5 0 kg /c m 2 ) br ok en ob se rv ed 2. 70 -3 .3 0 c or e ga p 3. 30 -3 .5 0 n o sa m pl e s ilt y lo am m as si ve , s of t 5y 5/ 1 15 % , 5 y 5/ 3, 5 m m n o n o c om m on t ra ns iti on al , la go on (0 .3 0 kg /c m 2 ) 2c m 3. 50 -3 .7 0 4 s an dy lo am m as si ve , s of t 5y 5/ 1 n o n o 10 26 n o c om m on a br up t la go on (0 .3 0 kg /c m 2 ) 3. 70 -3 .8 0 n o sa m pl e lo am y sa nd m as si ve , s of t 5y 5/ 1 n o n o n o m an y a br up t la go on (0 .3 0 kg /c m 2 ) 3. 80 -4 .0 0 5 lo am la m in at ed , s of t 5y 5/ 1 n o n o 0 32 n o c om m on a br up t la go on (0 .3 0 kg /c m 2 ) 4. 00 -4 .5 0 6, 7 s ilt y cl ay m as si ve , s of t n 5 n o n o 0, 0 27 , m an y ca rb on ac eo us n o t ra ns iti on al , s al t m ar sh , a lo am ; l oa m (0 .5 0 kg /c m 2 ) fle ck s 4c m so il ho riz on 4. 50 -4 .7 0 8 s ilt y lo am m as si ve , f irm 5y 6/ 2 25 % , 5 y 6/ 1, 2 m m h ar d, 12 s om e ro ot le ts , n o t ra ns iti on al 2b c k so il (1 .7 5 kg /c m 2 ) 10 % , 5 y 6/ 4, 2 m m 25 m m , 5 % φ = 1m m 3c m ho riz on 4. 70 -4 .8 5 9 s ilt y lo am m as si ve , v er y fir m 2. 5y 6/ 3 20 % , 5 y 6/ 1, 3 m m h ar d, 21 n o n o a br up t 2c k1 s oi l (3 .5 0 kg /c m 2 ) 15 % , 5 y 5/ 6, 3 m m 3 m m , 2 % ho riz on 4. 85 -5 .3 0 10 s ilt y lo am m as si ve , v er y fir m 2. 5y 6/ 4 10 % , n 6, 5 m m h ar d, 30 n o n o t ra ns iti on al , 2c k2 s oi l (3 .5 0 kg /c m 2 ) 10 % , 2 .5 y 5/ 6, 3 m m 27 m m , 8 % 5c m ho riz on 5. 30 -5 .5 0 11 s ilt y lo am m as si ve , v er y fir m 5y 7/ 2 20 % , 5 y 6/ 4, 4 m m n o 38 n o n o t ra ns iti on al , 2c s oi l (3 .5 0 kg /c m 2 ) 8c m ho riz on 5. 50 -6 .0 0 15 s ilt y lo am la m in at ed , f irm n 6 n o n o 33 n o n o n ot o bs er ve d f lu vi al , (1 .2 0 kg /c m 2 ) ov er ba nk 6. 00 -7 .0 0 c or e ga p 7. 00 -7 .5 0 n o sa m pl e s an dy lo am la m in at ed , f irm n 6 n o n o n o n o a br up t f lu vi al , (1 .7 5 kg /c m 2 ) cr ev as se s pl ay 7. 50 -7 .8 0 16 s ilt y cl ay la m in at ed , f irm 5y 7/ 1 n o n o 33 n o n o a br up t f lu vi al , lo am (1 .7 5 kg /c m 2 ) ov er ba nk 7. 80 -8 .3 0 n o sa m pl e s an dy lo am f in in g up w ar d, s of t 5y 7/ 1 n o n o n o n o a br up t f lu vi al , (0 .7 5 kg /c m 2 ) cr ev as se s pl ay t a b . 1 t h e m a in c h a ra ct e ri st ic s o f th e s a m p le d in te rv a l i n c o re p m 1 . 206 p. mozzi et al. dd eepp tthh ss aamm ppll ee tt eexx ttuu rree ss ttrr uucc ttuu rree mm uunn ssee llll mm oott ttllee ss cc aacc oo 33 cc aacc oo 33 oo .. mm .. pp llaa nntt rr eemm aaii nnss ss hhee llllss lloo ww eerr ff aacc iiee ss m # (u s d a ) (a nd p .p . t es t) cc ooll oouu rr % , c ol or , d im en si on s nn oodd uull eess % % bboo uunn ddaa rryy 2. 40 –2 .8 0 1 s ilt y cl ay la m in at ed , s of t 5y 5/ 1 n o n o 15 24 n o n o a br up t la go on (0 .7 5 kg /c m 2 ) 2. 80 -2 .9 0 2 s an dy lo am m as si ve , s of t 5y 4/ 1 n o n o 0 64 n o n o a br up t s al t m ar sh , a (0 .7 5 kg /c m 2 ) so il ho riz on 2. 90 -3 .4 5 3 s an dy lo am m as si ve , s of t 5y 3/ 1 n o n o 0 60 m an y w oo d an d ca ne n o a br up t s al t m ar sh , (0 .7 5 kg /c m 2 ) fr ag m en ts , 1 ÷3 m m a c s oi l h or iz . 3. 45 -3 .5 5 4 s ilt y cl ay m as si ve , f irm 5g 5/ 1 n o n o 0 17 c om m on w oo d an d ca ne n o t ra ns iti on al , s al t m ar sh , (1 .2 5 kg /c m 2 ) fr ag m en ts , 1 ÷3 m m 3c m c g so il ho riz . 3. 55 -4 .0 0 5 s ilt y lo am m as si ve , s of t 5y 6/ 1 15 % , 5 y 6/ 8, 4 m m c ac o 3, h ar d, 13 9 n o n o t ra ns iti on al , 2c kg 1 so il (0 .7 5 kg /c m 2 ) 3m m , 7 % 3c m ho riz on 4. 00 -5 .2 0 6, 8, 7 s ilt y cl ay lo am m as si ve , v er y fir m 5y 7/ 1 30 % , 2 .5 y 6/ 8, 1 5m m c ac o 3, h ar d, 28 , 3 5, 2 9 n o n o t ra ns iti on al , 2c kg 2 so il (4 .5 0 kg /c m 2 ) 20 % , 1 0g y 6/ 1, 2 0m m 3m m , 5 % 5c m ho riz on 5. 20 -5 .9 0 9, 10 s ilt y cl ay lo am m as si ve , v er y fir m n 6 30 % , n 7, 2 0m m n o 30 , 2 9 n o n o t ra ns iti on al , 2c g so il (4 .5 0 kg /c m 2 ) 15 % , 5 y 5/ 6, 1 0 m m 10 cm ho riz on 5. 90 -6 .2 0 n o sa m pl e s ilt y lo am la m in at ed , v er y 10 y 6/ 1 n o n o n o n o a br up t f lu vi al , e fir m ( 3. 25 k g/ cm 2 ) na tu ra l l ev e 6. 20 -6 .9 0 11 ,1 2 s ilt y lo am la m in at ed , f irm 10 y 6/ 1 n o n o 32 ,3 0 n o n o a br up t f lu vi al , (1 .7 5 kg /c m 2 ) na tu ra l l ev ee 6. 90 -8 .7 0 13 s an dy lo am la m in at ed , s of t 10 y 6/ 1 n o n o n o n o a br up t f lu vi al , c ha nn el t a b . 2 t h e m a in c h a ra ct e ri st ic s o f th e s a m p le d in te rv a l i n c o re v e co n 6 . dd eepp tthh ss aamm ppll ee tt eexx ttuu rree ss ttrr uucc ttuu rree mm uunn ssee llll mm oott ttllee ss cc aacc oo 33 cc aacc oo 33 oo .. mm .. pp llaa nntt rr eemm aaii nnss ss hhee llllss lloo ww eerr ff aacc iiee ss m # (u s d a ) (a nd p .p . t es t) cc ooll oouu rr % , c ol or , d im en si on s nn oodd uull eess % % bboo uunn ddaa rryy 2. 30 –2 .5 0 1 s ilt y lo am la m in at ed 10 y 5/ 1 n o n o 12 24 c om m on c ar bo na ce ou s n o a br up t s al t m ar sh fle ck s 2. 50 -2 .8 0 2 c la y lo am la m in at ed 10 g 4/ 1 n o n o 5 59 le av es o f c an es n o a br up t s al t m ar sh 2. 80 -3 .2 0 3b p ea t f ib ro us 10 y r 3/ 1 n o n o 0 21 3 p ea t n o t ra ns iti on al , s al t m ar sh , o 3c m so il ho riz on 3. 20 -3 .8 0 4 lo am la m in at ed 5g y 4/ 1 n o n o 0 48 n o n o a br up t c g so il ho riz on 3. 80 -4 .0 0 5 s ilt y cl ay m as si ve , f irm 10 y 5/ 1 15 % , 5 y 6/ 8, 4 m m s of t, 3m m , 3 % 0 14 n o n o n ot o bs er ve d 2b c g so il lo am ho riz on 4. 00 -4 .3 0 6 s ilt y lo am m as si ve , f irm 2. 5y 6/ 2 25 % , 5 y 6/ 1, 3 m m h ar d an d so ft, 0 11 n o n o a br up t 2c kg 1 so il 3m m , 8 % ho riz on 4. 30 -5 .0 0 8, 7 s ilt , s ilt y cl ay lo am m as si ve , f irm 5y 6/ 1 30 % , 5 y 6/ 4, 5 m m h ar d, 5 m m , 4 % 25 ,4 3 17 ,8 n o n o n ot o bs er ve d 2c kg 2 so il ho riz on t a b . 3 t h e m a in c h a ra ct e ri st ic s o f th e s a m p le d in te rv a l i n c o re a b 6 . brackish environments, with episodes of varying salinity in the water and soils. this may be due to the alternating prevalence of sea water vs. fluvial fresh-water of rivers flowing into the lagoon. from a palynological point of view, the results are consistent with those of the previous literature. particularly, the presence of sterile layers, which separate a lower group of sediments, attributed to a continental, fluvial environment, from an upper group with evident brackish characteristics, was observed by bertolani marchetti (1967). the sediments that lie unconformably on top of the caranto (above the dotted line n. 16 in fig. 2) were deposited in a paralic context, typical of the landward sector of the lagoon. here, tidal processes interacted with fluvial activity, in a metastable equilibrium which could rapidly change in space and time. subtidal flats, intertidal flats and tidal channels could alternate laterally (in space) or vertically (in the stratigraphy) with vegetated salt marshes and small deltas, the latter related to the delivery of fluvial sediments into the lagoon. such geomorphic and sedimentary model applies well to the complex stratigraphic record of the studied cores (fig. 2; tab. 1, 2, 3). considering the whole ne – sw transect of fig. 2, the lowermost lagoonal deposits are found at depths comprised between 1 and 2.5 m below mean sea level. in the observed lagoonal deposits there is a prevalence of subtidal / intertidal mud flat facies, with salt marshes (tab. 1, 2, 3); only in core er 32, at the depth of ca. 1.50 m below mean sea level, there is evidence of a sandy tidal channel (fig. 2). it is, furthermore, possible to recognize two main sedimentary events (separated by the dash line n. 15 in fig. 2). the sediments of the first one are altogether less than 1 m thick, and are capped by the organic horizons radiocarbon dated to the middle ages. these latter are pedogenetic a and o horizons, underlain by gley ac and c horizons, which constitute a weakly developed, subacid soil. the activity of soil forming processes implies the existence of a subaerial topographic surface, while the presence of near surface gley horizons indicates a high underground water table. this is consistent with the salt marsh environment shown by the pollen record. in fact, salt marshes lie immediately above the average high tide level, and are only seldom submerged during maximum high tides (albani et al., 1984; castiglioni, 1986). in vecon 6, where the a and ac horizons are well developed, the micropedological analysis of the underlying cg horizon allowed for the recognition of yellowish mottles and ferruginous nodules, which are indicative of occasional conditions above the water table. the greyish – greenish colour of the a horizon in pm 1 indicates a badly drained situation with permanent reducing conditions, and the same applies to the cg horizons under the o horizons in core er 32 and ab 6. the lateral variations from a horizons, with partly mineralized organic matter, and o horizons, made of indecomposed organic matter, can be interpreted as a hydro-pedosequence, where the former occupy the higher, relatively better drained topographic positions, and the latter the depressions. the average high tide level most probably used to cut the soil profile in cores er 32 and ab 6 at the lower boundary of the o horizons. therefore, the 1055 – 954 cal bp average high tide level is now ca. 2 m below the present mean sea level (core er 32), while the one of 640 in order to estimate the time-length required for the development of these soil horizons, some considerations can be made. the deactivation of the bassano megafan took place after 14,500 bp, probably before the onset of the holocene, when the sea level was still more than 50 m below the present day one. from that moment onwards, sedimentation in the bassano megafan stopped, and soil forming processes became dominant. the early and middle holocene mild environmental situation, with dense forest cover, involved optimal conditions for soil formation. at the same time, the continuous relative sea level rise brought about a progressive submersion of the alluvial plain that occupied the northern adriatic basin during the last glacial sea lowstand. by 6000 bp, the lagoon of venice had already started forming, which implies that the more distal fringes of the bassano megafan, were submerged and pedogenesis had already ceased. all this allows a time slice of 4000 to 8000 years for soil formation on this stretch of alluvial plain. the study area, in a more landward position, was still emerging at that time, and most probably all along the middle to late holocene. in our research, no evidence has been gathered about when the study area evolved to paralic, brackish conditions. an indication is provided by a recent investigation carried out in the ca’ tron area, on the northern lagoon shores about 15 km to the east of the study area, nearby the old mouth of the sile river in the lagoon. here, the maximum transgression on the late pleistocene alluvial plain has been dated to post roman times (bondesan & mozzi, 2002). if also in the study area the first lagoonal deposits were post roman, this would allow some other 4000 years to pedogenesis. in this framework, the studied caranto palaeosol may have formed in 8000 to 12,000 years. the palynological data clearly show that the apf falls to very low values in these weathered horizons. the drastic decrease of apf is, here, probably due to the alternating oxidative-reductive conditions and leaching during the soil formation. indeed, oxidation and subsequent wetting and drying cause damage of the exine (horowitz, 1992). in the samples collected in the layers above the caranto, a decrease of the microthermic elements and an increase of the deciduous broadleaf trees is recorded. this trend may be considered an index of climatic improvement. quercetum s.l. is well represented and quercus appears to be the leader tree; it reaches the widest expansion in samples vecon 6/4-3 and pm 1/5-4. the significant percentages of hygrophilous and hydrophilous plants, particularly alnus, underline the presence of alluvial environments and the occurrence of water bodies. the consistency of these data with the literature about the holocene (bertolani marchetti, 1967; accorsi et al., 1989; 1996; bertoldi, 1996; lowe et al., 1996; paganelli, 1996a), indicate that the deposits formed in the late holocene. this is coherent with the probable post roman age of the whole sequence, and with the medieval ages of the radiocarbon dated organic horizons intercalated in the sediments (fig. 2). as regards the vegetation with edaphic determinism, among the nap the alternate prevalence of cyperaceae and plants of fresh water habitats (typha cf. latifolia, sparganium/typha angustifolia, potamogeton, callitrichaceae) and halophytes (chenopodiaceae and plumbaginaceae) attests the presence of 207stratigraphy, palaeopedology and palynology of late pleistocene ... – 592 cal bp is 0.8 m below mean sea level (core ab 6). taking the 0.3 m a.s.l. high tide average height of the present day lagoon of venice (albani et al., 1984; castiglioni, 1986) as a reference, the mean sea level was respectively 2.3 and 1.1 m below the present one. this is a consequence of the relative sea level rise during the last centuries, deriving from the sum of the following phenomena: eustatic sea level rise, natural subsidence, man induced subsidence (since the second half of the 20th century). the second event buried these weakly developed palaeosols in late medieval and modern times. on top are the artificial landfills related to the land reclamation at the lagoon fringes during the 20th century. 77.. ccoonncclluussiioonnss the study of the sedimentary, pedological and palinological features of the cores, has enabled to recognize the sequence of events occurred in the late quaternary at the landward margin of the central sector of the lagoon of venice. during the last glacial maximum, the deposition of fluvial sediments took place in the study area, mainly as overbank fines with only limited sandy channel bodies. these deposits belong to the pleistocene brenta sedimentary system, the bassano megafan, which corresponds to a large stretch of the central veneto plain between the alpine piedmont and the lagoon of venice. arboreal vegetation was scant, and mainly consisted of microthermic elements. after the deactivation of this megafan, probably at the pleistocene – holocene transition, sedimentation in the area stopped and soil forming processes became dominant, acting on the calcareous, silty clay parent material of fluvial origin, probably for 8000 – 12,000 years. processes of redistribution of carbonates along the soil profile led to the formation of calcic b and c horizons, characterized by the accumulation of caco3 in nodules and crusts; just in one core (ab 6), the b horizon depleted of the carbonates by vertical leaching, which is normally on top of the calcic horizons, has been preserved. alternating oxidizing and reducing conditions, related to the fluctuation of the underground watertable, brought about greyish and yellowish mottling, and alteration of the pollen grains originally present in the sediment. this palaeosol corresponds to the so-called caranto level auctorum. it is in physical continuity with the calcisols of the stretch of plain at the back of the lagoon, belonging to the bassano megafan, and have similar pedogenetic features. it represents a major uncomformity in the stratigraphy of the lagoon area. the first lagoonal deposits in the study area are, most probably, of post roman age. they lie directly on top of the caranto palaeosol at depths comprised between 1 and 3 m below mean sea level. pollen analysis shows that salt marshes with halophytes formed in the higher parts of the tidal flats, while other areas evolved into more open lagoon environments, probably with recurrent input of fluvial sediments and water. less than 1 m of sediments were deposited during a first sedimentary event. its upper boundary corresponds to an unconformity of low rank, indicated by the presence of a slightly pedogenized level which formed in medieval times. the radiocarbon dating of organic o horizons of this soil, developed in a salt marsh environment, provides a chronostratigraphic support to the determination of the recent relative sea level rise. this is estimated to have been 2.3 m since 1055 – 954 cal bp to present day in porto marghera, enirisorse area, and 1.1 m since 640 – 592 cal bp to present day in porto marghera 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serandrei barbero r., albani a.d. & zecchetto s., 1997 palaeoenvironmental significance of a benthic foraminifera from an archaeological excavation in the lagoon of venice. palaeogeography, palaeoclimatology, palaeoecology, 113366,, 41-52. serandrei barbero r., lezziero a., albani a. & zoppi u., 2001 depositi tardo-pleistocenici ed olocenici nel sottosuolo veneziano: paleoambienti e cronologia. il quaternario, 1144(1), 9-22. stuiver m. & reimer p.j.,1993 extended 14c data base and revised calib 3.0 14c age calibration program. radiocarbon, 3355, 215-230. tosi l., 1994 l’evoluzione paleoambientale tardo-quaternaria del litorale veneziano nelle attuali conoscenze. il quaternario, 77(2), 589-596. 210 imp. guglielmin ppeerrmmaaffrroosstt ee ffoorrmmee ppeerriiggllaacciiaallii nneellllee nnoorrtthheerrnn ffooootthhiillllss ((bbaaiiaa tteerrrraannoovvaa,, tteerrrraa vviittttoorriiaa sseetttteennttrriioonnaallee,, aannttaarrttiiddee)) mmaauurroo gguugglliieellmmiinn11,, hhuunngg mm.. ffrreenncchh22 && ffrraanncceessccoo ddrraammiiss33 1prna, via g. matteotti, 22, 20035 lissone (mi), italia 2department of geography and earth sciences, university of ottawa, ottawa, ontario k1n 6n5, canada 3dipartimento di scienze geologiche, università “roma tre”, largo s. leonardo murialdo, 1, 00146 roma, italia riassunto permafrost e forme periglaciali nelle northern foothills (baia terranova, terra vittoria settentrionale, antartide) le forme periglaciali presenti nel territorio di baia terra nova sono rappresentate essenzialmente da poligoni, fessure da gelo (frost fissures) e coni di iniezione (injection cones). i poligoni, sviluppati su i terreni del younger drift, sono caratterizzati dalla presenza di cunei di ghiaia e sabbia (gravel and sand wedges) mentre su i terreni riferibili all’older drift sono stati rinvenuti cunei e vene di ghiaccio (ice wedges and veins). la contrazione termica responsabile della formazione di ambedue i tipi di cunei risulta attiva anche nelle attuali condizioni climatiche. i coni di iniezione sono comunemente associati a laghi perennemente gelati e vengono interpretati come forme dovute all’iniezione di acqua nel permafrost, così come accade in artico per la genesi dei pingo e dei ghiacciamenti superficiali (icings). notevole importanza per la dinamica morfologica dell’area riveste il numero di cicli di gelo e disgelo che si alternano nel terreno. l’azione del crioclastismo (frost shattering) non è però molto diffusa ed anche il fenomeno di fessurazione per gelo (frost wedging) nel substrato roccioso è limitato all’azione di espansione delle discontinuità naturali preesistenti. abstract permafrost and frozen phenomena of the northern foothills (terranova bay, northern victoria land, antarctica) permafrost-related landforms in the terra nova bay territory are mainly polygons, frost fissures, and injection cones. the polygons developed on younger drift are characterized by gravelly-sandy filling while those affecting older drift show the occurrence of ice wedges and veins. thermal contraction responsible for the genesis of both landforms shows to be active at present. injection cones are commonly associated to perennially frozen lakes. they are interpreted as landforms due to the injection of water into the permafrost as it happens for the genesis of pingos and seasonal icings in the arctic. a relevant role in the morphodynamic context of the area is that plaid by the high number of freezing/thawing cycles in the ground. however, frost shattering is not widespread and even frost-wedging in the bedrock is only restricted to the expansion of the pre-existing natural discontinuities. parole chiave: permafrost, poligoni da fessure da gelo, coni di iniezione, cunei di ghiaccio, antartide. keywords: permafrost, frost fissure polygons, injection cones, ice wedges, antarctica. il quaternario italian journal of quaternary sciences 1166(2), 2003, 151-157 11.. iinnttrroodduuzziioonnee il progetto nazionale di ricerche in antartide (pnra), avviato nel 1985, ha affrontato essenzialmente nelle sue prime fasi di svolgimento temi legati al glacialismo e all’evoluzione delle spiagge oloceniche; solo a partire dal 1996 è stato approvato un progetto focalizzato sulla distribuzione del permafrost e sul suo regime termico nel territorio di baia terranova (terra vittoria settentrionale), sede della base scientifica italiana in antartide. questo territorio è contraddistinto da una alta percentuale di aree deglaciate, una tra più elevate del continente antartico, se si eccettuano le dry valleys e la penisola antartica. i valori della temperatura media mensile variano tra –1,5 °c in gennaio e –22,5 °c in agosto; la temperatura media annua è di -14,7 °c (nel periodo 1987-1994). i venti dominanti provengono dai quadranti occidentali con velocità che spesso superano i 17 nodi (baroni, 1996); le precipitazioni a carattere interamente nevoso vengono stimate attorno i 270 mm/anno (piccardi et al., 1994). nei mesi di novembre e dicembre 1998 è stata svolta, in collaborazione con l’università di ottawa, una campagna di ricerche morfologiche avente come obiettivo principale lo studio della geomorfologia periglaciale nelle northern foothills, in prossimità della base italiana (fig.1). nel presente lavoro vengono illustrati i primi risultati delle indagini suddette con particolare riguardo alle forme generate nell’area da processi criogenici connessi con la presenza di permafrost continuo. 22.. iill ppeerrmmaaffrroosstt aa bbaaiiaa tteerrrraannoovvaa si definisce permafrost un qualsiasi materiale che rimane congelato per almeno due anni consecutivi (muller, 1959) indipendentemente dalla sua natura e dal contenuto o meno di ghiaccio al suo interno. nell’area in esame sono presenti diversi tipi di permafrost: depositi glaciali sovrastanti corpi di ghiaccio relitto massivo (simpson crags; boulder clay glacier); depositi glaciali rimaneggiati da soli/geliflusso sovrastanti il substrato roccioso; 152 m. guglielmin, h.m. french & f. dramis substrato roccioso ricoperto da uno strato sottile e discontinuo di depositi glaciali e ubicato a quote superiori a quelle dell’ultimo massimo glaciale (350-400 m s.l.m); substrato roccioso ubicato a quote più basse di tale limite; cordoni morenici olocenici e rock glaciers; spiagge oloceniche sollevate isostaticamente. a partire dal 1996 è in funzione nell’area una stazione automatica di monitoraggio del regime termico del permafrost (guglielmin & dramis, 1998). la stazione, ubicata sul boulder clay glacier, alla quota di 205 m s.l.m., circa 5 km a sud della base di baia terra nova, registra i valori orari, della radiazione solare incidente, della temperatura dell’aria a 4 m di altezza sul terreno e della temperatura del suolo a sei diverse profondità. i primi due sensori sono posti a 2 e 30 cm di profondità all’interno di un till di ablazione, il terzo è posto a -60 cm, immediatamente al di sotto del limite superiore del ghiaccio massivo che caratterizza il sottosuolo dell’area. i rimanenti tre (posti rispettivamente a -160, -260 e -360 cm) sono ubicati all’interno del ghiaccio, del quale è stata determinata la diffusività termica pari a 0,106 °c/m2. in base a questo valore la profondità della minima variazione termica annua (zero annual amplitude zaa) risulta ubicata a circa -11 m, con una temperatura di -15°c. 33.. rreeggiimmee tteerrmmiiccoo ddeelllloo ssttrraattoo aattttiivvoo lo strato attivo è per definizione la porzione più superficiale del permafrost, interessata da periodici scongelamenti stagionali e ne rappresenta quindi la parte termicamente più dinamica e più efficace sotto l’aspetto morfogenetico. il regime termico dello strato attivo è infatti importante per la genesi e l’evoluzione di diverse forme direttamente legate al permafrost oltre che di alcune forme dovute a meccanismi di geliflussione. nell’area in esame lo spessore dello strato attivo è piuttosto esiguo, essendo in genere compreso tra i 15 e i 20 cm anche se localmente, specie nelle spiagge oloceniche e sui pendii settentrionali più ripidi con roccia affiorante, si ritiene che possa arrivare sino ad 1 m o poco più. in particolare l’andamento del regime termico di boulder clay glacier è mostrato in fig. 2, mentre i valori massimi, minimi e medi delle temperature registrate nel 1996-97 alle diverse profondità sono illustrati in tab. 1a. notevole importanza per la dinamica morfologica del permafrost riveste il numero di cicli di gelo e disgelo che si alternano nel terreno. in tab. 1b è illustrato l’andamento giornaliero dei cicli alla profondità di 2 cm, calcolati rispettivamente per un punto di congelamento pari a 0, -2 e –4 °c (valori legati alla presenza di elevati tenori salini nella neve e nel suolo). come è possibile osservare nella tabella il numero di cicli di gelo e disgelo registrati risulta rilevante e maggiore di quanto misurato nella maggior parte degli ambienti periglaciali (french, 1996). l’azione del crioclastismo (frost shattering) non è però molto diffusa ed anche il fenomeno di fessurazione per gelo (frost wedging) nel substrato roccioso è limitato all’azione di espansione delle discontinuità naturali preesistenti. fig. 1 ubicazione delle forme investigate: suoli strutturati (stelle nere) e cunei di iniezione (triangoli neri) a northern foothills e vicino alla base italiana di baia terra nova, antartide. locations of the i n v e s t i g a t e d landforms: patterned grounds (black stars) and frost heaved mounds (black triangles) of the northern foothills and near terra nova bay station, an-tarctica. 153permafrost e forme periglaciali ... t °c t °c t °c t °c t °c t °c t °c -360 cm -260 cm -160 cm -60 cm -30 cm -2 cm aria massimo -10,2 -8,3 -4,4 -2,4 -1,1 10,7 5,4 minimo -23,7 -24,9 -27,7 -29 -30,2 -35,3 -38 media -17,45 -17,28 -17,08 -16,98 -16,83 -16,9 -16,06 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 dic. ’96 >0°c 0 0 0 0 0 0 0 0 1 0 0 0 1 1 2 0 0 0 3 0 0 2 1 1 0 0 0 0 3 1 1 >-2°c 1 1 2 2 0 0 3 0 0 5 0 0 1 2 1 2 1 2 3 1 1 2 0 2 2 2 3 1 4 1 2 >-4°c 2 1 1 0 3 1 1 1 2 0 4 3 1 0 2 2 2 2 1 1 1 2 0 0 0 1 1 0 0 0 0 gen.’97 >0°c 4 0 5 2 0 0 0 0 0 0 0 0 0 2 1 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 >-2°c 0 3 1 1 1 3 2 0 2 2 2 0 3 2 2 4 3 1 0 2 1 3 2 0 0 0 1 0 0 0 0 >-4°c 0 0 0 0 1 1 1 2 1 0 3 2 1 0 0 1 1 1 2 1 1 2 3 4 2 1 2 0 1 1 1 feb.’97 >0°c 0 0 0 0 0 >-2°c 0 0 0 0 0 >-4°c 1 0 0 1 1 nov.’97 >0°c 0 0 0 0 0 0 0 0 0 0 0 2 3 2 0 0 0 2 1 0 0 0 0 >-2°c 0 0 3 0 0 0 0 0 1 0 0 2 1 2 0 0 0 3 0 1 0 0 0 >-4°c 2 2 1 3 1 0 1 2 1 2 1 0 0 0 3 1 1 0 0 2 0 0 0 tab. 1 temperature del terreno registrate dal 1 dicembre 1996 al 7 novembre 1997 alla stazione di monitoraggio di boulder clay glacier. ground temperatures recorded at boulderclay glacier monitoring site, december 1, 1996 november 7, 1997. 1b) frequenza giornaliera delle oscillazioni termiche attraverso le temperature di 0 c°, -2 c° e –4 °c, usando i valori medi orari: totale > 0°c = 42; >-2°c = 100; > -4°c = 97. 1b) number of daily occurrences per day of ground temperature cycles passing 0 c°, -2 c°, and –4 c°, using hourly data: total > 0 c° = 42; >-2 c° = 100; > -4 c° = 97 1a) valori massimi, minimi e medi (°c). 1a) maximum, minimum and average temperatures (c°). fig. 2 regime termico del permafrost presso la stazione di monitoraggio di boulder clay glacier del periodo 1996-97 (da guglielmin & dramis, 1998). ground temperature regime at boulder clay glacier permafrost monitoring station, 199697 (from guglielmin & dramis, 1998). ggiioorrnnii ((11 ddiicceemmbbrree 11999966 - 11 ddiicceemmbbrree 11999977)) pp rroo ffoo nn dd iittàà (( ccmm )) 154 44.. ppoolliiggoonnii ddii ffeessssuurree ddaa ggeelloo una delle forme più diffuse nelle aree deglaciate delle northern foothills è quella dei suoli strutturati poligonali (non sorted polygons). queste forme, già descritte nella letteratura precedente (péwé, 1959; black & berg, 1966, black 1973; bondesan et al., 1997*), interessano sia i depositi glaciali dello younger drift (sovrastanti ghiaccio morto), sia i depositi glaciali dell’older drift (sovrapposti al basamento rocccioso), sia le spiagge oloceniche. i poligoni sono caratterizzati da diametri di 15-20 m e da solchi perimetrali di larghezza compresa tra 1e 2 m e profondità media di 0,5 m. bisogna inoltre sottolineare come non siano in realtà visibili fessure aperte sulla superficie ma solamente allineamenti preferenziali di massi e ciottoli. la rete generata da questi poligoni è essenzialmente di due tipi: random-ortogonale ed esagonale. talora sono stati osservati anche pattern diversi di tipo rettilineo come quello di simpson crags, che sembra essere controllato dalla presenza sottostante di crepacci nel ghiaccio morto massivo. lo stesso tipo di pattern rettilineo è stato osservato anche presso capo sastrugi, dove sono visibili numerose fessure, con una spaziatura regolare tra gli 8 e i 12 m, e ortogonali rispetto alla direzione di elongazione della dorsale rocciosa. con ogni probabilità il pattern delle fessure è in questo caso influenzato dall’assetto strutturale delle fratture nel substrato roccioso uno dei cui set principali presenta una direzione coincidente con quella prevalente delle fessure stesse. in tutte le sezioni eseguite la parte più superficiale delle fessure risulta riempita da ghiaia e ciottoli con struttura openwork. i clasti risultano nettamente isoorientati secondo la direzione delle fessure e spesso verticalizzati. da un punto di vista dinamico è da ritenere che queste forme siano attive anche ai giorni nostri per diverse ragioni. una evidenza dell’attività della fessurazione da gelo (frost cracking) durante la stagione invernale è rappresentata dall’osservazione (con l’ausilio di una sonda metallica) di fessure aperte in profondità (fino oltre 80 cm presso simpson crags e fino a 15 cm presso m. browning). un’altra testimonianza della contemporaneità del processo di fessurazione è data dal ritrovamento della prosecuzione delle fessure attraverso corpi di ghiaccio di rigelo stagionale (simpson crags). la maggior parte dei poligoni osservati non presenta cunei di ghiaccio al di sotto dei solchi mostrando invece cunei di ghiaia e sabbia a sezione triangolare, con larghezza compresa tra 0,5 e 1 m e di analoga profondità. i sedimenti suddetti hanno la stessa composizione litologica dei depositi circostanti anche se, in generale, con un’arricchimento nella frazione sabbiosa. la presenza di cunei di ghiaccio è stata riscontrata solamente sul m. browning, alla quota di 720 m s.l.m., su un till di ablazione sovrastante il substrato roccioso. in questa località sono presenti poligoni poco sviluppati e delineati solamente da piccoli solchi con ciottoli allineati e verticalizzati. in base al colore della matrice del till (5yr 5/6; 2.5 yr 5/6) e tenuto conto dell’assenza di clasti di vulcaniti provenienti dal m. melbourne, si ritiene che questo deposito sia da riferire al “older drift” definito da orombelli et al. (1991). i cunei di ghiaccio sono in genere abbastanza sottili (10-15 cm di larghezza) e si estendono per 30-50 cm al di sotto della tavola del permafrost; anche in questo caso sono presenti nello strato attivo sovrastante cunei di ghiaia e sabbia (fig. 3). 55.. ddiissccuussssiioonnee dalle osservazioni fatte appare chiaro come la maggior parte dei poligoni presenti nel territorio delle northern foothills sia soggetto a processi di fessurazione tuttora attivi ma che l’accrescimento dei cunei sia alquanto limitato come testimoniato dall’eseguità dei “rampart” laterali (20-30 cm di altezza) e dalle ridotte dimensioni dei cunei stessi (1 m al massimo di profondità e larghezza). tali dimensioni sono nettamente inferiori a quelle medie note in artico (6-10 m di profondità e 2-3 m di larghezza). bisogna inoltre sottolineare come gli unici e modesti cunei di ghiaccio rinvenuti presso m. browning non esprimano morfologicamente veri e propri poligoni e siano circoscritti al di sopra di till più antichi suggerendo così condizioni genetiche relativamente più m. guglielmin, h.m. french & f. dramis fig. 3 cuneo di ghiaccio ritrovato all'interno del older drift a m. browning. si noti la forte alterazione del suolo nella parte inferiore della trincea. ice wedge found in older drift at mt. browning. note the high grade of soil alteration in the lower part of the trench. 155 umide di quelle attuali. i poligoni osservati sono per la maggior parte attivi, con cunei costituiti da sabbia e ghiaia, e si rinvengono in tutti i tipi di terreno (specialmente nei drift più recenti e nei depositi di spiaggia). essi sono a luoghi contraddistinti da profili convessi e da ramparts laterali poco accentuati che non sembrano riflettere un processo di “upthrusting” quanto piuttosto una forma di accumulo connessa con l’espansione termica dello strato attivo (mackay, 1980). questo processo di espansione e il relativo movimento laterale del materiale secondo direttrici radiali rispetto al centro del poligono si producono quando esistono rilevanti variazioni termiche nel terreno (anche rimanendo al di sotto di 0 °c). tale fatto è dimostrato dai dati rilevati nella stazione di boulder clay dove si registrano temperature del suolo anche di 10 °c maggiori di quelle dell’aria e variazioni termiche anche superiori all’interno della medesima giornata. per quantificare l’entità del movimento in gioco basta ricordare che mackay (1980) nella regione del mackenzie delta in canada ha misurato movimenti di circa 0.25 cm/anno: considerando che la temperatura dell’aria e del suolo sono certamente più basse nell’area in esame, si può ragionevolmente ritenere che l’entità del movimento sia qui sensibilmente inferiore. in generale appare chiaro che, sotto l’aspetto tipologico, i poligoni osservati non sono riferibili a cunei di ghiaccio ma non risultano neppure riferibili ai tipici cunei di sabbia (sand wedges) quali quelli descritti da carter (1983) e murton & french (1993) nell’artico nordamericano. infatti il riempimento delle fessure non risulta mai costituito dalla sola frazione sabbiosa ma in prevalenza da ghiaie con sabbia e ciottoli in cui si è avuto certamente un arricchimento di sabbia per trasporto eolico. terminologicamente si preferisce però non utilizzare il termine proposto da péwé (1959) “tesselations” (mosaici) in quanto non esprime chiaramente né i processi morfogenetici né le caratteristiche sedimentologiche dei cunei e si propone quindi di utilizzare il termine “poligoni di fessure da gelo” (frost fissure polygons) per enfatizzare soprattutto il processo che genera la fessurazione e non la tipologia del riempimento. bisogna inoltre sottolineare come i piccoli cunei di ghiaccio ritrovati nell’older drift del m. browning sono i primi realmente documentati in antartide in quanto né nei lavori di black né in quelli di péwé è possibile vedere sezioni riferibili a questa tipologia. si vuole sottolineare infine che i poligoni di fessure da gelo sono forme tipicamente connesse al permafrost indipendentemente dalla tipologia del substrato e quindi non attribuibili ad altri processi connessi con la dinamica glaciale. data la discontinuità nel tempo del processo di fessurazione, tali poligoni non possono essere utilizzati per la datazione relativa dei terreni su cui sono sviluppati, ma il loro monitoraggio risulta di grande interesse in quanto connesso con le variazioni di bilancio energetico della superficie e quindi con le variazioni climatiche. 66.. ccoonnii ddii iinniieezziioonnee nell’area in esame sono stati da tempo stati riconosciuti numerosi accumuli detritici di forma conica a base circolare o ellittica, di altezza compresa tra i 2 e 4 m (eccezionalmente fino ai 8-10 m), costituiti per lo più da ghiaia, ciottoli e blocchi con scarsa matrice in superficie e talora contraddistinti (nella parte più superficiale) dalla presenza di mirabilite (chinn et al., 1989). molti degli accumuli sono ubicati in prossimità o nel mezzo di laghi perennemente congelati (fig. 4). questi elementi morfologici sono stati considerati in letteratura come forme di ablazione differenziale associate a ghiacciai ricoperti o a ghiaccio morto (chinn et al., 1989; orombelli et al., 1991; lozej et al., 1992). quattro accumuli conici sono stati analizzati nella zona di boulder clay glacier, attorno alla stazione di monitoraggio del permafrost: due ad enigma lake, uno sull’amorphous glacier e uno a tarn flat. caratteristica comune a tutti i coni osservati in prossimità o in corrispondenza di laghi gelati è la minore alterazione superficiale del deposito rispetto al drift circostante. tale differenza di alterazione è particolarmente evidente nel caso di amorphous glacier e tarn flat. proprio nel caso di tarn flat (fig. 5) è possibile osservare come il fondale dei laghi completamente drenati appaia meno alterato degli affioramenti circostanti analogamente a quanto avviene per la superficie del cono. sulle superfici gelate dei laghi di boulder clay, enigma lake ed inexpressible island sono state osservate anche forme di doming sempre accompagnate da fessurazioni radiali. tali fenopermafrost e forme periglaciali ... fig. 4 cono di iniezione all'interno del lago localizzato presso la stazione di boulder clay glacier. si noti anche il doming del ghiaccio lacustre. the frost-heaved mounds of the pond near the boulder clay glacier station. note the doming of the ice surface of the lake. 156 meni sono del tutto simili a quelle riscontrate nei blister da ghiacciamento superficiale (icing blisters) in molte località del artico canadese e che si formano nella stagione invernale e primaverile. si ricordano, a titolo esemplificativo, gli esempi di churchill, manitoba nel maggio 1981 (french & gilbert, 1982), dello yukon centrale nel marzo 1982 (pollard & french, 1984) e della parte centrale dell’isola di banks nell’aprile 1979 (french, 1996). 77.. iill ccaassoo ddii eenniiggmmaa llaakkee enigma lake è stato oggetto di numerose e dettagliate indagini geofisiche (lozej et al., 1992; 1994) e di indagini geomorfologiche e glaciologiche (chinn et al., 1989; lozej et al., 1992) in quanto presenta la peculiarità di avere nella sua parte centrale una sottile copertura glaciale e due coni detritici, dei quali il maggiore raggiunge i 5 m di altezza ed il minore di circa 2 m. chinn et al., (1989) hanno ipotizzato che tale forma rappresenti la parte visibile di un corpo glaciale risalente al ross sea drift e presente nella depressione prima della formazione del lago. del tutto simile è la spiegazione di lozej et al. (1992) secondo i quali il ghiaccio lacustre avrebbe circondato e in parte sepolto un corpo glaciale relitto. dalle osservazioni effettuate durante il mese di novembre 1998 è stato tuttavia possibile osservare come siano presenti non solo alcune zone di doming con numerose fratture radiali ma anche una rilevante quantità di acqua liquida in superficie ed in tasche al di sotto della superficie. e’ stata inoltre rilevata la presenza di ghiaccio di rigelo, di tipo non colonnare, intruso all’interno del ghiaccio lacustre circostante a dimostrazione dell’esistenza di processi di iniezione idrostatica. in questo contesto appare utile ricordare che gli stessi autori hanno già rilevato l’esistenza di un emissario verso la tethys bay e che la presenza di acqua superficiale e di variazioni areali del bacino lacustre sono documentate anche dall’analisi di fotografie aeree dalle quali risulta circa il 5% di aumento di area nella porzione settentrionale nel 1985 rispetto al 1956 (orombelli, 1990). alla luce di queste evidenze è possibile rielaborare i dati prodotti nel corso degli anni dagli autori precedenti seguendo una diversa ipotesi genetica. utili risultano in particolare le analisi del contenuto in trizio riportate in chinn et al. (1989) che evidenziano la presenza a circa 3 m di profondità di un orizzonte riferibile al periodo postnucleare (1954-1963) interposto tra ghiaccio prenucleare con un valore isotopico di 23 t.u. la presenza di un valore così elevato significa senza dubbio che acqua recente si è intrusa in ghiaccio più antico e che questa si è congelata durante la stagione invernale (mantenendo così un valore isotopico più basso di quello attuale). per tutte le considerazioni sopra esposte si ritiene più semplice spiegare la formazione dei coni detritici come prodotti del medesimo processo che genera il doming nei laghi. la formazione di ghiaccio di iniezione generato dalla presenza di acqua allo stato liquido, congelando nei mesi invernali, può esercitare una pressione idrostatica tale sia da creare il doming, che da rialzare il letto del lago (sul quale è presente uno strato di sedimenti dello spessore di 30-50 cm), dando così origine ai coni detritici stessi. nelle zone artiche, forme analoghe vengono distinte in perenni (come i pingo) e stagionali, note in generale come “seasonal frost mounds” (porsild, 1938; mackay, 1979), entrambe connesse con il processo di iniezione di ghiaccio generato dal rigelo di acque sotterranee circolanti. talvolta però le forme perenni mostrano sui fianchi la formazione di forme stagionali (porsild, 1938) come, per altro verso, alcune forme stagionali (blister da ghiacciamento) possono riprodursi per diversi anni nel medesimo sito (van everdingen, 1978; pollard & french, 1985). si ritiene che nel caso delle forme individuate nelle northern foothills si tratti di forme originate stagionalmente ma di durata perenne dal momento che non vengano smantellate con il disgelo durante la stagione estiva. di rilevante interesse paleoclimatico ed ambientale sarebbe capire se questi episodi di crescita stagionali siano continui oppure discontinui e corrispondenti a stagioni estive particolarmente od eccezionalmente calde tali da generare la quantità di acqua circolante necessam. guglielmin, h.m. french & f. dramis fig. 5 il cono di iniezione di tarn flat. si noti la differenza di alterazione tra il materiale costituente il cono e la circostante copertura detritica. the frost-heaved mound of tarn flat. note the different weathering of the rocks that composed the mounds and the surrounding debris cover. ria all’iniezione del ghiaccio durante il successivo inverno. proprio per questo motivo come indicato da overpeck et al. (1998) si potrebbe utilizzare il monitoraggio di queste forme per evidenziare eventuali cambiamenti climatici globali. rriinnggrraazziiaammeennttii la presente ricerca è stata svolta all’interno del progetto 2a.1.3. del prna (progetto nazionale di ricerca in antartide). si ringraziano i responsabili dell’organizzazione e della logistica della base italiana di baia terra nova ed i piloti della new zealand helicopters. un particolare ringraziamento a luigi bonetti per l’aiuto sostanziale nella realizzazione delle sezioni criostratigrafiche e delle perforazioni. bbiibblliiooggrraaffiiaa baroni c., 1996 antarctic geomorphological and glaciological 1:250,000 map series. mount melbourne quadrangle (victoria land). pnra. museo nazionale dell’antartide siena, italy. black r.f., 1973 growth of patterned ground in victoria land, antarctica. in: permafrost; north american contribution, second int. permafrost conf., yakutsk, ussr, washington d.c., national academy of science, publ. 2115, 193-203. black r.f. & berg t.e., 1966 patterned ground in antarctica. proceed. first int. permafrost conf., national academy of sciences, national research council of canada, publ. 1287, 121-127. bondesan a., meneghel m., salvatore m.c. & stenni b., 1997 non sorted polygons in the terra nova bay area (victoria land). in: antarctic region: geological evolution and processes, ricci c.a. ed., terra antartica publ., siena, 957-963. carter l.d., 1983 fossil sand wedges on the alaskan arctic coastal plain and their palaeoenvironmental significance. proceed. fourth int. permafrost conf., national academy press, washington d.c., 109-114. chinn t.j., whitehouse i.e. & hofle h.c., 1989 report on a reconnaissance of the glaciers of terranova bay area. geol. jb., ser. e, 3388, 299-319. french h.m., 1996 the periglacial environment, 2nd ed. longman ltd., 341 pp. french h.m. & gilbert r., 1982 periglacial phenomena near churchill, manitoba. can. nat., 110099, 433-444. guglielmin m. & dramis f., 1998 permafrost as a climatic indicator in northern victoria land (antarctica). proceed. seventh int. permafrost conf., yellowknife, n.w.t., canada, vol. 1, 147148. lozej a., tabacco i., meneghel m., orombelli g., smiraglia c. & longinelli a., 1992 radio-echo soundings of enigma lake (northern foothills, victoria land, antarctica). mem. soc. geol. it., 4466, 103-115. mackay j.r., 1979 an equilibrium model for hummocks (non-sorted circles), garry island, northwest territories. geological survey of canada, paper 79-1 a, 165-167. mackay j.r., 1980 the origin of hummocks, western arctic coast. can. j. earth sci., 1177, 996-1006. müller f., 1959 beobachtung uber pingos. meddelelser om gronland, 115533 (3), 127 pp. murton j.b. & french h.m., 1993 sand wedges and permafrost history, crumbling point, pleistocene mackenzie delta, canada. proceed. sixth int. permafrost conf., vol. 1, beijing science press, 482-487. orombelli g., 1990 glaciers and glacial morphology at terra nova bay: an opportunity for significant studies on environmental and climatic global changes. mem. soc. geol. it., 4466, 9-16. orombelli g., baroni c. & denton g.h., 1991 late cenozoic glacial history of the terra nova bay region, northern victoria land, antarctica. geogr. fis. dinam. quat., 1133, 139-163. overpeck j., hughen k., hardy d., bradley r., case r., douglas m., finney b., gajewski k., facoby g., jennings a., lamoureaux s., lasca a., macdonald g., moore j., retelle m., smith s., wolfe a. & zielinski g., 1997 arctic environmental change of the last four centuries. science, 227788, 1251-1256. péwé t.l., 1959 sand wedge polygons (tesselations) in the mcmurdo sound region, antarctica. am. j. sci., 225577, 545-552. piccardi g., udisti r. & casella f., 1994 seasonal trends and chemical composition of snow at terra nova bay (antarctica). int. j. envir. anal. chem., 5555, 219-234. pollard w.h. & french h.m., 1984 the groundwater hydraulics of seasonal frost mounds, northern yukon. can. j. earth sci., 2211, 1073-1081. pollard w.h. & french h.m., 1985 the internal structure and ice crystallography of seasonal frost mounds. j. glaciol., 3311, 157-162. porsild a.e., 1938 earth mounds in unglaciated arctic northwestern america. geogr. rev., 2288, 46-58. van everdingen r.o., 1978 frost mounds at bear rock near fort norman, n.w.t. 1975-1976. can. j. earth sci., 1155,, 263-276. 157permafrost e forme periglaciali ... ms. ricevuto il 21 agosto 2002 testo definitivo ricevuto il 28 gennaio 2003 ms. received: august 21, 2002 final text received: january 28, 2003 amq short notes 26_2 zerboni divito monegato available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 25 (2), 2012, xi xv report on the inqua-aeomed field-trip workshop ‘reconsidering loess in northern italy’ (po plain, 1-3 july 2013) rivka amit 1, andrea zerboni 2 1 geological survey of israel, jerusalem, israel. 2 dipartimento di scienze della terra “a. desio”, università degli studi di milano, italy. corresponding author: a. zerboni <andrea.zerboni@unimi.it> abstract: this report presents the results of the field-trip workshop entitled ‘reconsidering loess in northern italy’ (po plain, 1-3 july 2013), organized in the framework of the aeomed project of the inqua terpro commission. the workshop focuses on presenting and discussing the sources and formation processes of the loess in the po plain area. the sedimentological, palaeopedological, palaeoclimatic and palaeoseismic aspects of five main loess sequences in the po plain (val sorda, gajum, monte netto, ghiardo, boschi di carrega) were presented and discussed in the field. the discussions carried out during three field days aim to map knowledge gaps and to define the next scientific goals in the field of loess research in the po plain in particular and in italy in general . keywords: aeomed; loess; po plain loess basin; upper pleistocene palaeoclimate. introducing the aeomed project the second workshop of the aeomed project, 1-3 july 2013, (loess and aeolian additions to current surface soils and paleosols in mediterranean climate) was aimed to visit and discuss some of the most representative loess sequences along the northern and southern fringe of the po plain loess basin (pplb), northern italy. the main long-term aims of the aeomed project (https:// ppsg2011.uni-hohenheim.de/94176), which is part of the terpro commission of inqua, are: (i) to assess the spatial pattern of loess deposits across the mediterranean: (ii) to analyze loess successions in similar geomorphic units of various mediterranean environments; (iii) to estimate the potential of dust emission and deposition in the various mediterranean environments, based on the underfig. 1 map illustrating the distribution of loess in the po plain (modified from cremaschi, 1990); the sites visited during the workshop are also indicated. 1) pre-quaternary bedrock; 2) alluvial plain; 3) present-day sea extent; 4) moraine systems; 5) loess on fluvial terraces and moraine ridges; 6) loess on karst plateaus; 7) loess in rock shelters; 8) loess on erosional surfaces; 9) direction of dominant winds during loess sedimentation; 10) possible sw boundary of the loess basin. amit r., zerboni a. xii standing of the mechanisms of dust and loess generation, transportation and deposition. short term aims of aeomed project for the following two years (2013-2015) are: (i) to reconsider the loess in northern italy, mainly the po plain loess; (ii) to study loess sites with non glacial aeolian loess deposits, specifically loess and dust derived from the sahara desert in sites at the central and southern italy; (iii) to map the loess in italy along a north-south climatic transect. this project will contribute to identify sources of recent and palaeo-dust/loess around the mediterranean sea and to evaluate rates of loess/dust deposition in the context of palaeoclimate reconstructions, and soil formation processes. the workshop held in italy on july 2013 entitled ‘reconsidering loess in northern italy’ was aimed to bring together loess experts from italy and elsewhere to discuss the loess topic in italy in the context of the loess issue in europe and around the mediterranean basin in several key sites at the pplb. basic questions were discussed such as variety of loess types, sources of the different loess types, climatic deriving forces for loess transportation and deposition, loess accumulation processes, the formation of loessial soils in glacial and non-glacial environments and its paleoclimatic implications. the workshop was organized by r. amit, a. zerboni, e. costantini, s. carnicelli, m. cremaschi, f. livio, and a.m. michetti as part of inqua terpro activities. wide board of expertise attended at the meeting (30 scientists) including geomorphologists, palaeopedologists, sedimentologists, quaternary geologists, geoarchaeologists and palaeoseismologists. in addition 9 grants were available for young researchers from italy, israel and mexico. additional support, derived from the università degli studi di milano, università degli studi dell’insubria, università degli studi di fig. 2 the participants to the workshop visiting the val sorda sequence. fig. 3 a detail of the loess/paleosols sequences deformed by a gravity graben at monte netto; note the thick red paleosol buried by loess. reconsidering loess in northern italy workshop firenze and cra-abp, allowed opening new trenches and soil pits at each study site. reconsidering loess in northern italy: an example of the extensive po plain loess in the framework of european terrestrial palaeorecords, the loess in italy in general, and the loess in the po plain in particular, represents an extraordinary sedimentary record for palaeoenvironmental reconstructions (fig. 1). despite of many systematic studies carried out in the last decades on loess sequences located at northern, eastern and southern margin of the po plain, loess in italy is somewhat overlooked in comparison to the classical sequences described in central and north europe. as a result, crucial data are excluded from the analyses and interpretations of the loess in europe. the term loess refers herein to silty sediments, which have been transported and accumulated by aeolian activity (cremaschi, 1987a). however, because the loess deposit in northern italy are generally thin and can be affected by synand post-depositional weathering, soil formation and colluviation, sometimes their characteristics do not fully meet the standard requirements generally accepted for classical loess. thus the identification of loess in all studied sites was based on geomorphological criteria, textural and mineralogical characteristics and geoarchaeological evidence (cremaschi, 1987a; 1990). two of the visited sites are located in the eastern part of the garda lake area (fig 2). the val sorda sequence is a 5 m-thick, very well preserved upper pleistocene stratigraphic section consisting of the succession of a till, capped with a rubified eemian paleosol, which is overlain by a colluvial layer and a thick loess unit, which includes three chernozem paleosols (cremaschi, 1987b; ferraro, 2009). the loess sequence is capped, compacted and preserved by glacial deposits dated to mis 2. the texture of the loess is sandy silty with no much clay. the well sorted silt and fine sand composed mainly by muscovite and quartz with subangular quartz grains. the age of the upper chernozem -like soil derived from humic acids is c. 28 ka bp (cremaschi, 1987b); osl and irsl dating yield an age for the aeolian deposition between c. 63 and 19 ka bp (cremaschi, 1987b; ferraro, 2009). the importance of val sorda loess sequence is its high degree of preservation. the fact that the original features of the loess and loessial soils are well preserved is the result of the burial by the uppermost thick moraine deposits that isolate the loess sequence from later and recent pedogenic processes. the loess sequence at gajum site (cremaschi, 1987b) is similar to the loess sequence at val sorda, with local colluvial material present at the bottom and aeolian loess at the top. differently from the loess section in val sorda, the loess in gajum site was accumulated in a depression at the top of a karst plateau and was not buried by any glacial or fluvial deposit. thus it was subject to continuous weathering and pedogenic processes, resulting in more weathered loess deposit; radiocarbon ages indicate that loess deposition occurred up to c. 42 ka bp (cremaschi, 1987). monte netto site (capriano del colle, bs) is an isolated hill in the middle of the northern po plain (fig. 3), whose growing is due to the amplification of a buried thrustrelated anticline since the middle pleistocene (livio et al., 2009). a highly rubified, polycyclic paleosol covered by few tens of centimeters of loess characterize the top of the anticline. at the distal part of the exposure the thickest loess sequence of the whole pplb is found. the continuous growing of the anticline during the late quaternary allowed such an exceptional thick accumulation of loess. the upper part of the section corresponds to at least three events of aeolian sedimentation, two of which are osl dated to the upper pleistocene, while a later aeolian actifig. 4 loess sequences at the southern fringe of the pplb: (a) the participants discussing the significance of loess and paleosols at the ghiardo site; (b) the loess sequence at the boschi di carrega site. note in (b) a deep and dark horizon with high concentration of mn concretions. xiii amit r., zerboni a. xiv vity has been radiocarbon dated to the end of the lgm. loess sedimentation at monte netto started after an intensive phase of pedogenesis of fluvial sediments, likely occurred under interglacial conditions. this produced a highly rubified paleosol rich in illuvial clay. subsequent weathering phases gave rise to the formation of paleosols progressively less rubified and rich in clay toward the top of the sequence, which may correspond to several upper pleistocene interstadials. palaeopedological indeces also confirm a progressive reduction of the intensity of pedogenesis rate during the upper pleistocene. textural changes between fresh and weathered loess is underlined by the occurrence of horizons showing a high concentration of manganese concretions. the sequence also preserves evidence of strong palaeoearthquakes, which contributed to the displacement of the loess strata and the pedological horizons (livio et al., 2009). the last two sequences are located at the foot of the apennines (fig. 4), and are represented by thick loess strata covering deeply weathered pleistocene fluvial sediments. the aeolian loess went through intense to moderate pedogenesis, which result in different loessial soil profiles in each site. in the soils we generally identify processes of accumulation of illuvial clay, decalcification, and acidification, which were followed by release, translocation, reduction/oxidation and precipitation of mn and fe through hydromorphism (cremaschi, 1987b). ghiardo site (cavriago, re) is a complex loess sequence, deposited on pleistocene alluvial terraces (cremaschi, 1987b). this sequence records an upper pleistocene aeolian sedimentary phases of loess accumulation (c. 63 to 36 ka bp), which underwent intense weathering processes. moreover, the surface buried by loess and its initial phase of deposition are contemporaneous with the dwelling of mousterian hunters, while the top part of the soil bears traces of chalcolithic land management, which appears to have influenced the soil forming processes. the high terrace of boschi di carrega (collecchio, pr), is covered by loess accumulated during the late pleistocene. this loess sequence correlates with the loess sequence of the ghiardo terrace. soil data collected since the 60s (ferrari and magaldi, 1968), show deep horizons developed in loess, forming complex soils with most of them acidified at the top. to sumarize, although the loess deposits and loessial soils in each site were slightly different, the main sedimentological and pedological characteristics are similar mainly in their stratigraphic appearance, particle size distribution, and mineralogy. in places where the loess was not buried by fluvial or fluvio-glacial sediments and was subject to continuous pedogenic processes the loess is more weathered and more clayey. this arise the possibility that the loess in the po plain is derived from the same local sources, which might be the po flood plains and the po influents, which were exposed during glacial time for long periods and were subject to intense winds at that time. possibly, the combination of increased wind strength with availability of sediments allowed the formation and/or transportation and deposition of loess over a large area, from fig. 5 group photo of part of the participants to the aeomed workshop. reconsidering loess in northern italy workshop the adriatic coast to the inner part of the po plain, at the foot of western alps (cremaschi, 1990). the fact that most of these loess areas were not covered by ice during glacial times, arise the possibility that the source for the loess can be primary silt size fractions or local proximal sands, which were subject to aeolian abrasion to form silt size grains. these preliminary assumptions should be supported by more data and more studies, which will be conducted in the near future. concluding remarks and future work the results of this workshop will be the basis for planning the next steps of the aeomed project working group, which will aim to study the non-glacial loess of italy (e.g., costantini et al., 2009). the data from the non-glacial loess will be later compared to the glacial loess type in the pplb and around the mediterranean to better understand the process of loess formation, transportation, accumulation, distribution and its association with soil formation and climate. in a wider perspective, as italy represents a natural bridge between the north africa/sahara and europe, it would be important to understand any contribution of saharan dust to italian loess, to compare it to the extant dust flux and to infer any possible modifications triggered by recent global changes. during the conclusive discussion, we decided to integrate all information regarding the loess in the pplb to draw a map showing the distribution and properties of the loess sediment and soils. the map of pplb will be published in a collaborative paper, which will present and interpret all published and new data regarding the loess in northern italy. the newly opened loess-soil pits will be dated by osl, and results integrated with published and unpublished ages for loess formation to get a better time constrain on the loessial periods in the po plain. references costantini e.a.c., priori s., urban b., hilgers a., sauer d. protano g., trombino l. (2009) multidisciplinary characterization of the middle holocene eolian deposits of the elsa river basin (central italy). quaternary international, 209, 107-130. cremaschi m. (1987a) loess deposits of the plain of the po and of the adjoining adriatic basin (northern italy). in: pecsi m., french h.m. (eds.), loess and periglacial phenomena. akademiai kiado, budapest, 125140. cremaschi m. (1987b) paleosols and vetusols in the central po plain (northern italy). a study in quaternary geology and soil development. edizioni unicopoli, milano, pp. 306. cremaschi m. (1990) the loess in northern and central italy: a loess basin between the alps and the mediterranean sea. c.n.r., centro di studio per la stratigrafia e petrografia delle alpi centrale, milano, italy, pp. 187. ferrari g., magaldi d. (1968) i paleosuoli di collecchio ed il loro significato. ateneo parmense-acta naturalia, 4, 57-92. ferraro f. (2009) age, sedimentation, and soil formation in the val sorda loess sequence, northern italy. quaternary international, 204, 54-64. livio f.a., berlusconi a., michetti a.m., sileo g., zerboni a., trombino l., cremaschi m., mueller k., vittori e., carcano c., rogledi s. (2009) active fault-related folding in the epicentral area of the december 25, 1222 (io = ix mcs) brescia earthquake (northern italy): seismotectonic implications. tectonophysics, 476, 320-335. ms. received: october 15, 2013 final text received: october 15, 2013 xv imp.lugli& composizione dei sedimenti sabbiosi nelle perforazioni lungo il tracciato ferroviario ad alta velocità: indicazioni preliminari sull’evoluzione sedimentaria della media pianura modenese stefano lugli, simona marchetti dori, daniela fontana & filippo panini dipartimento di scienze della terra, università degli studi di modena e reggio emilia, largo s. eufemia 19, 41100 modena. e-mail: lugli.stefano@unimore.it, marchettidori.simona@unimore.it, fontana.daniela@unimore.it, panini.filippo@unimore.it riassunto: lugli s. et al., composizione dei sedimenti sabbiosi nelle perforazioni lungo il tracciato ferroviario ad alta velocità: indicazioni preliminari sull’evoluzione sedimentaria della media pianura modenese. (it issn 0394-3356, 2004). le perforazioni effettuate lungo il tratto modenese del tracciato ferroviario ad alta velocità hanno fornito numerosi campioni di sabbie prelevate in profondità fino a 40-50 m dal piano campagna, per un intervallo temporale che presumibilmente copre il pleistocene sommitale e l’olocene. l’esame composizionale di 28 campioni di sabbie prelevati da 6 perforazioni ha permesso di evidenziare come la sedimentazione fluviale nella media pianura modenese sia drasticamente mutata a partire da circa 10-12 ka. la composizione dei sedimenti sabbiosi più recenti sembra riconducibile a quella dei corsi d’acqua minori che attraversano oggi la pianura nel tratto compreso tra i fiumi secchia e panaro. i sedimenti sabbiosi più antichi presentano invece composizioni diverse, particolarmente arricchite in feldspati. tali differenze composizionali possono riferirsi a combinazioni di vari fattori quali: a) variazioni nella litologia del substrato per fenomeni tettonici e/o per variazioni nello sviluppo del reticolo idrografico, b) fenomeni di riciclo di sedimenti fluviali antichi, c) effetti di alterazione per variazioni climatiche. i dati composizionali acquisiti, uniti a dati di tipo stratigrafico, suggeriscono che tra i sedimenti tardo-pleistocenici e quelli olocenici sia presente una significativa discontinuità stratigrafica di importanza regionale. abstract: lugli s. et al., composition of sands in cores along the high-speed rail (tav): preliminary indications on the sedimentary evolution of the modena plain. (it issn 0394-3356, 2004). the modena alluvial plain has been geologically investigated in great detail and is characterized by a spectacular abundance of archaeological sites of various age. for this reasons the area may be considered a natural laboratory for the reconstruction of the recent sedimentary evolution of the po plain. the alluvial plain area examined for this study has an approximate extent of 150 km2 and is located at the northern side of the northern apennines thrustand fold-belt, where streams draining the chain flow toward the northeast into the po river. detailed modal analyses by point-counting of thin sections show that modern stream sands in the modena plain show similar overall compositional fields, but can be discriminated on the base of key-components, such as quartz, feldspar, carbonate and lithic fragments. the study of sand sediments indicates that the compositional fields have not varied significantly since the neolithic. the only major diagenetic process is the formation of carbonate concretions (caliche), which can be easily recognized as secondary particles during point counting of thin sections. these results indicate that the reconstruction of the recent evolution of the local drainage system is possible by comparing ancient with modern fluvial sand compositions. the drilling of numerous wells along the new high speed train tract (tav) provided us with new insight on the sedimentary evolution of the plain through time. the samples recovered from 6 wells reaching depths up to -50 m show that the sand sediments older than 1012 kyr, have a significant shift in composition from the modern ones. this compositional change consists in a marked overall increase of quartz and feldspar components. the compositional variations can be explained by the combination of various factors: a) significant change in the bedrock lithology through time induced by tectonics and/or change in the local drainage pattern, and b) recycling of older fluvial sediments enriched in feldspar. because the sands older than 10-12 kyr compared to the overlaying olocenic and modern sediments are enriched in feldspar, which is considered a particularly alterable component, the compositional differentiation can be related to effects induced to glacial-interglacial climate changes but not to post-depositional diagenetic processes. the considerable change in sand composition and the stratigraphy of the deposits suggest dramatic geographical, environmental and depositional variations supporting the observation that a regional unconformity separates the late pleistocene from the olocene sediments. parole chiave: depositi fluviali, quaternario, pianura padana, composizione sabbie. keywords: fluvial sediments, quaternary, po plain, sand composition. il quaternario italian journal of quaternary sciences 17(2/1), 2004, 379-389 1. introduzione la pianura modenese, per la particolare abbondanza di siti archeologici e di sondaggi geognostici, rappresenta un laboratorio naturale per lo studio dell’evoluzione sedimentaria della pianura padana. alla ricca documentazione già disponibile, si aggiunge la notevole mole di dati di sottosuolo acquisita recentemente in occasione della realizzazione del tracciato ferroviario ad alta velocità. il presente lavoro illustra i primi dati composizionali ottenuti analizzando campioni di sabbie provenienti da perforazioni effettuate lungo tale tracciato. lo scopo è quello di fornire un contributo alla comprensione della complessa evoluzione sedimentaria del settore modenese della pianura padana (fig.1). indagini di dettaglio da noi recentemente effettuate (lugli et al., 2003), hanno permesso di individuare specifiche petrofacies caratterizzanti le sabbie attuali e recenti dei principali corsi d’acqua modenesi in funzione di alcuni parametri composizionali (quarzo+feldspati, 380 s. lugli et al. carbonati totali, frammenti litici). tale studio ha inoltre dimostrato che la composizione delle sabbie si è mantenuta pressoché costante a partire dal neolitico. questi risultati hanno fornito uno strumento importante per l’indagine dei sedimenti sabbiosi nel sottosuolo modenese, per l’identificazione degli apparati fluviali di pertinenza e della loro evoluzione. le perforazioni lungo il tracciato tav si sono rivelate una utile occasione per effettuare un confronto con i dati già in nostro possesso sulle composizioni delle sabbie dei corsi d’acqua modenesi, al fine di ottenere informazioni più complete sull’evoluzione della sedimentazione fluviale nel settore meridionale della pianura padana. 2. inquadramento stratigrafico dell’alta e media pianura le alternanze di peliti e di depositi conglomeratico-sabbiosi di ambiente alluvionale che caratterizzano la pianura emiliano-romagnola sono il risultato di cicli deposizionali che si sviluppano a partire dal pleistocene medio (da circa 650 ka) su di una superficie di discontinuità stratigrafica che li separa dai più antichi depositi di ambiente litorale. lo sviluppo di questa superficie è legata ad un sollevamento regionale che, nei settori prossimi al margine appenninico, ha il carattere di una superficie di erosione subaerea (r e g i o n e e m i l i a romagna & eni-agip, 1998). a scala regionale, all’interno dei depositi continentali quaternari sono stati riconosciuti due principali cicli, corrispondenti a due unità, o a unità a limiti inconformi (sintema emiliano-romagnolo inferiore e superiore (amorosi & farina, 1994; 1995; regione emilia-romagna & eni-agip, 1998; gasperi & pizziolo, in stampa) separate da una discontinuità stratigrafica collocabile tra 350 e 450 ka (regione emiliaromagna & eni-agip, 1998), connessa ad un ulteriore episodio di sollevamento della catena (fig. 2). questi due sintemi sono stati ulteriormente suddivisi in unità di rango inferiore la cui organizzazione verticale riflette lo sviluppo di un ciclo trasgressivo-regressivo. il riconoscimento di queste unità di rango inferiore è agevole nell’alta pianura, dove sui depositi grossolani sono presenti paleosuoli più o meno sviluppati. nella media e bassa pianura invece, l’assenza di interruzioni prolungate nella sedimentazione, oltre al mancato o limitato sviluppo di pedogenesi ed un minor contrasto litologico, rendono difficile la loro definizione (gasperi & pizziolo, in stampa). a scala regionale, il più recente ciclo trasgressivoregressivo completo (subsintema di villa verucchio) è suddiviso in una porzione pelitica (unità di niviano), deposta durante la penultima fase interglaciale alla quale segue, nelle aree a ridosso del margine appenninico, e fino all’altezza della via emilia (fig. 3), una potente porzione grossolana (unità di vignola), corrispondente alla successiva fase glaciale e deposta durante un intervallo cronologico antecedente 15-18 ka. esso è ritenuto genericamente più antico di 30 ka (gasperi & pizziolo, in stampa), anche se la possibile correlazione con un orizzonte grossolano presente nell’appennino bolognese fa supporre una età della base non più antica di 20-23 ka (amorosi et al., 1996). nella pianura emiliana, la sedimentazione tardofig. 1 idrografia principale dell’alta e media pianura modenese e traccia del percorso della linea tav. e’ illustrata la distribuzione dei corpi ghiaiosi che costituiscono le conoidi pedemontane tardo-pleistoceniche dei fiumi secchia e panaro e del t. tiepido (modificata da pellegrini & zavatti, 1979). i = sezione geologica di fig. 4; ii = sezione geologica di fig. 5; iii = sezione geologica di fig. 6. schematic hydrography of the modena alluvial plain crossed by the new high speed train tract (tav). the late pleistocene piedimont gravel fans of the secchia, panaro and tiepido streams are illustrated (modified from pellegrini & zavatti 1979). i = geological section of fig. 4; ii = geological section of fig. 5; iii = geological section of fig. 6. fig. 2 schema stratigrafico dei depositi continentali quaternari della pianura emiliano-romagnola (modificata da regioneemilia-romagna & eni-agip, 1998; gasperi & pizziolo, in stampa). le sigle a0-4 si riferiscono alle unità idrostratigrafiche distinte in regione-emilia-romagna & eni-agip (1998). stratigraphic sketch of the quaternary continental deposits in the emilia romagna plain (modified from regione-emiliaromagna & eni-agip, 1998; gasperi & pizziolo, in press). the abbreviations a0-4 refer to the hydrostratigraphic units of regione-emilia-romagna & eni-agip (1998). pleistocenica ed olocenica è rappresentata da depositi di piana alluvionale (subsintema di ravenna), ad esclusione delle aree prossime al margine appenninico, dove sono presenti corpi ghiaioso-sabbiosi (depositi di canali intrecciati, fig. 3). nella media pianura modenese questa unità a limiti inconformi è caratterizzata da una parte inferiore, tra 15 ed 25 m di profondità dal piano campagna, ricca di materia organica (depositi di palude o di piana alluvionale mal drenata) con una età radiometrica tra 15 e 10 ka (gasperi & pizziolo, in stampa). un altro orizzonte ricco di materia organica, si rinviene al di sopra del precedente, tra 7,5 e 11 m di profondità ed ha fornito età radiometriche intorno a 4 ka. gli scavi e le perforazioni eseguite nell’area cittadina hanno documentato la presenza entro il subsintema di ravenna di una unità stratigrafica superiore (unità di modena) costituita dai sedimenti alluvionali pelitici deposti dopo l’età romana, ed in prevalenza durante la crisi climatica databile all’alto medioevo (fig. 3). l’unità, potente 5-8 m si sovrappone ad una superficie pedogenetica poco sviluppata e si ritiene sia stata prodotta dalle esondazioni di un corso d’acqua minore (t. fossa-cerca o formigine) che scorreva nei pressi della città in epoca storica (ga s p e r i et al., 1989; cremaschi & gasperi, 1989; fazzini & gasperi, 1996; gasperi & pizziolo, in stampa). nelle zone a nord di modena, l’identificazione delle unità a limiti inconformi precedentemente citate risulta più difficile a causa della mancanza di orizzonti ghiaiosi correlabili a quelli della media ed alta pianura. i profili geologici trasversali lungo la media pianura modenese attualmente disponibili sono illustrati in fig. 4 e 5. dal loro esame è possibile determinare l’orizzonte ghiaioso corrispondente all’unità di vignola e separarlo dai depositi sovrastanti dove le ghiaie passano alle alternanze di sabbie e limi del subsintema di ravenna. come si evince dalla estensione delle conoidi ghiaiose tardo-pleistoceniche (fig. 1), le ghiaie presenti nel sottosuolo cittadino sono probabilmente attribuibili al f. secchia. solo un corso d’acqua con un considerevole bacino idrografico e con una efficienza di trasporto elevata può infatti aver trasportato depositi ghiaiosi fino a molti chilometri oltre lo sbocco vallivo. più a nord gli episodi grossolani non sono presenti e l’intero record stratigrafico è dominato da depositi pelitici di piana alluvionale (fig. 6). 2.1. un nuovo profilo trasversale: il tracciato tav l’esecuzione dei sondaggi penetrometrici ed i carotaggi per la realizzazione della linea ferroviaria ad alta velocità milano-bologna, alcuni chilometri a nord di modena, ha permesso di acquisire un nuovo profilo stratigrafico che si spinge fino a 40-50 m di profondità dal piano campagna, orientato trasversalmente alla direzione dei corsi d’acqua appenninici (fig. 1 e 7) (valloni et al., 2003). dal profilo si può osservare come la sezione stratigrafica sia grosso modo suddivisibile in due parti. nei primi 25-30 m della sezione, i corpi sabbiosi sono rari e discontinui, suggerendo una correlazione con i depositi limosi e sabbiosi sovrastanti le ghiaie dell’unità di vignola, (pleistocene sommitale e dell’olocene del subsintema di ravenna). a conferma di ciò, sono dispo381composizione dei sedimenti sabbiosi ... nibili due datazioni radiometriche di un livello continuo di torbe rinvenuto nella parte basale di questa unità più superficiale. le datazioni sono state eseguite su campioni ubicati esternamente all’area studiata (baio, comunicazione personale) e hanno fornito un’età di 11,8 e 11,2 ka. tali età radiometriche consentono anche di correlare questo orizzonte pelitico con l’unità sommitale distinta nella pianura ad est del f. reno (unità b2: fig. 3 colonna stratigrafica schematica del sottosuolo nel centro urbano di modena secondo i dati di cremaschi & gasperi (1989) e gasperi & pizziolo (in stampa). legenda: 1) peliti prevalenti con orizzonti sabbiosi; 2) corpi ghiaioso-sabbiosi; 3) livelli con resti organici; 4) orizzonte pedogenizzato. schematic stratigraphic column of the modena urban area (data from cremaschi & gasperi 1989 and gasperi & pizziolo, in press). legend: 1) pelites with sand horizons; 2) grave-sand bodies; 3) organis-rich layers; 4) pedogenetic horizons. 382 fig. 4 sezione geologica traversale alla pianura modenese passante a sud del centro urbano che evidenzia la distribuzione in profondità dei corpi ghiaiosi (da gasperi et al., 1989). la linea tratteggiata in grassetto divide la parte superiore, con scarsi corpi ghiaiosi (subsintema di ravenna) da quella inferiore, caratterizzata da un notevole sviluppo di depositi grossolani. la linea tratteggiata inferiore rappresenta il limite dei dati. geological section transversal to the modena plain showing the distribution of the gravel bodies at depth, south of the urban area (from gasperi et al., 1989). the hatched thick line separates the upper gravel-poor portion (ravenna subsyntem) from the lower gravel-rich part. the lower hatched line mark the data limit. fig. 5 sezione geologica attraverso l’area urbana di modena (a nord della via emilia) nella quale è evidenziata (linea tratteggiata) il limite tra la porzione superiore costituita da peliti e corpi sabbiosi discontinui (subsintema di ravenna) e la porzione sottostante ricca in corpi ghiaioso-sabbiosi (unità di vignola). in corrispondenza del centro cittadino è evidenziata l’unità di modena (puntinato) con depositi di epoca post-romana (modificata da fazzini & gasperi, 1996). geological section along the modena urban area (north of via emilia) showing the limit (hatched line) between the upper gravel-poor portion (ravenna subsyntem) and the lower gravel-rich part (vignola unit). below the urban area is present the modena unit (dotted), characterized by post-roman age deposits (modified from fazzini & gasperi, 1996). fig. 6 sezione stratigrafica trasversale della pianura modenese all’altezza di carpi e ravarino. la sezione è ubicata circa 7 km a nord del tracciato della linea tav. sono messi in evidenza i rari e discontinui corpi sabbiosi intercalati a peliti (da: gruppo di studio sulle falde acquifere della pianura padana, 1979). geological section transversal to the modena plain near carpi and ravarino. the section is located about 7 km north of the tav track. notice the rare and discontinuous sand bodies intercalated into the pelites (from gruppo di studio sulle falde acquifere della pianura padana, 1979). s. lugli et al. 383 amorosi et al., 1996). valloni et al. (2003) collegano i livelli torbosi con età di circa 12 ka, alla fase di disattivazione delle conoidi fluviali legato alla trasgressione flandriana. ulteriori dati cronologici potranno provenire dalle indagini su alcuni campioni di materia organica da noi prelevati durante l’esecuzione dei sondaggi. lungo il profilo corrispondente alla linea tav, l’orizzonte sottostante 25-30 m di profondità è più ricco di corpi sabbiosi e può essere correlato con l’unità di vignola (fig. 7). tra le due porzioni dovrebbe essere presente una superficie di discontinuità corrispondente ad una prolungata interruzione della sedimentazione posteriore alla fase di costruzione delle conoidi pedemontane; la sezione studiata ne rappresenta l’area esterna, di transizione alla vera e propria pianura alluvionale. la deposizione delle conoidi si sviluppò, come accennato, durante o subito dopo l’ultima fase glaciale tardo-pleistocenica, od in corrispondenza di una fase particolarmente intensa di sollevamento della catena, come suggerito dalle ricerche in aree adiacenti (amorosi et al., 1996). la possibilità di prelevare campioni di sabbie durante l’esecuzione dei lavori di perforazione per la linea ferroviaria ha fornito un nuovo strumento indipendente di verifica del quadro stratigrafico e del modello interpretativo di riferimento. l’analisi composizionale può permettere infatti di verificare, anche lungo una trasversale più distale e meno definita dal punto di vista litologico se, come ipotizzato per il sottosuolo dell’area urbana, i depositi alluvionali appartenenti all’unità di vignola e quelli sovrastanti di pertinenza del subsintema di ravenna, presentino un’alimentazione dovuta a differenti apparati fluviali. gli orizzonti sabbiosi infatti, diversamente da quelli pelitici che derivano da esondazioni che interessano potenzialmente vasti tratti di pianura, sono legati a forme ed ambienti deposizionali strettamente connessi all’alveo fluviale (barre di canale, barre di meandro, depositi di argine, depositi di rotta) e dunque possono documentare le divagazioni spaziali e temporali di singoli corsi d’acqua. questa possibilità di verifica presuppone che vi sia stata, almeno durante il pleistocene sommitale e l’olocene, una sostanziale stabilità nel segnale composizionale relativo ai vari corsi d’acqua. 3. composizione dei sedimenti sabbiosi nelle perforazioni tav 3.1. metodi le perforazioni effettuate lungo il tratto modenese del tracciato ferroviario ad alta velocità hanno fornito numerosi campioni di sabbie prelevate in profondità fino a 40-50 m dal piano campagna. le perforazioni realizzate per il tracciato tav hanno attraversato prevalentemente sedimenti pelitici con intercalazioni sabbiose di modesta entità, per un intervallo temporale che presumibilmente copre il pleistocene sommitale e l’olocene. per il presente studio sono stati presi in esame 28 campioni di sabbie prelevati da 6 perforazioni nella porzione del tracciato tav che corre tra i fiumi secchia e panaro, a nord dell’abitato di modena, per uno sviluppo complessivo di 5,5 km (fig. 8, 9). fig. 7 sezione stratigrafica lungo il tracciato della linea tav (modificata da valloni et al., 2003). la linea tratteggiata indica il limite fra la porzione superiore (subsintema di ravenna) e la porzione sottostante (unità di vignola), sono indicate le perforazioni dalle quali sono stati prelevati i campioni di sabbie analizzati. geological section along the tav track (modified from valloni et al., 2003). the hatched line shows the limit between the upper ravenna subsyntem and the lower vignola unit. the sampled wells are also shown. fig. 8 ubicazione delle perforazioni studiate lungo il tracciato ferroviario ad alta velocità. location of studied wells along the new high speed train tract (tav). composizione dei sedimenti sabbiosi ... 384 la frazione sabbiosa di tali campioni è stata separata nei diversi intervalli granulometrici mediante setacciatura. la frazione fine (0,250-0,125 mm) è stata impregnata attraverso resina epossidica per la realizzazione di sezioni sottili, colorate per il riconoscimento dei feldspati (houghton, 1980). sulle sezioni è stata condotta l’analisi modale al microscopio ottico mediante conteggio di circa 300 granuli, secondo la metologia gazzi-zuffa (gazzi, 1966; dickinson, 1970; zuffa, 1985), che permette di calcolare, partendo dai dati ottenuti, i vari parametri dei principali diagrammi classificativi proposti in letteratura. lo schema classificativo utilizzato (cibin & di giulio, 1996), mostrato in tab.1, comprende anche componenti intrabacinali e antropici, quali laterizi, bioclasti penecontemporanei e concrezioni carbonatiche diagenetiche, esclusi in fase di elaborazione dei dati in quanto non diagnostici della provenienza dei sedimenti fluviali. l’errore che viene compiuto utilizzando il conteggio al tavolino integratore di 300 granuli corrisponde a 2 σ = 2% per un componente presente al 5% (5% ± 2) al 95% di confidenza. un componente presente al 50% è invece caratterizzato da 2 σ = 5,7 % (50% ± 5,7) al 95% di confidenza (howarth, 1998). per semplicità di lettura tali errori non sono riportati nei diagrammi classificativi presentati. 3.2. risultati i risultati composizionali ottenuti dai conteggi al tavolino integratore sono stati confrontati con i dati ottenuti da lugli et al. (2003) sulle sabbie oloceniche e attuali dei corsi d’acqua che solcano il territorio modenese (secchia, panaro, tiepido, grizzaga e cerca) e sono sintetizzati nella tabella 1 e in fig. 10 e 11. l’analisi dei sedimenti fluviali attuali ha evidenziato campi composizionali distinti per i diversi fiumi, sulla base del contenuto in quarzo, feldspati, litici carbonatici e ofiolitici. in particolare il sistema fluviale secchiagrizzaga-cerca mostra al suo interno una certa affinità e registra la prevalenza della componente silicoclastica su quella carbonatica terrigena. i depositi dei fiumi panaro e tiepido registrano invece prevalenza dei litotipi carbonatici all’interno della frazione terrigena. la maggior parte dei campioni analizzati in questo lavoro provenienti dai sondaggi tav mostra composizioni affini a quelle caratteristiche dei corsi d’acqua cerca e grizzaga, mentre soltanto tre campioni risultano simili a quelli del fiume panaro e nessuno a quelli del fiume secchia (fig. 10 e 11). più in dettaglio, i campioni analizzati possono essere suddivisi in due gruppi principali: quelli al di sopra e quelli al di sotto dei livelli di torba riferibili ad una età di circa 12 ka (sensu valloni et al., 2003) posta a circa 19-20 m dal piano campagna. nei diagrammi ternari q+f-carb-litici la maggior parte dei campioni presenti al di sopra dei livelli di torba mostra composizioni affini a quelle caratteristiche del torrente cerca (fig. 10). la quasi totalità dei campioni con età maggiore di fig. 9 stratigrafie delle perforazioni tav esaminate (non in scala). le frecce indicano i campioni di sabbie analizzati. stratigraphic columns of the studied wells along the tav track (not to scale). arrows point to the analyzed sand samples. s. lugli et al. 385 t a b . 1 , p a g . 1 c o m p o si zi o n e m o d a le d e i c a m p io n i a n a liz za ti p re le va ti d a lle p e rf o ra zi o n i t a v . m o d al c o m p o si ti o n o f sa n d s fr o m t h e s tu d ie d w e lls a lo n g t h e t a v t ra c k. s 7 2 -1 4, 5 s 7 2 -1 9, 5 s 7 2 -2 1, 5 s 7 222 p 1 43 23 p 1 43 24 p 1 83 14 ,5 p 1 81 32 ,5 p 1 81 39 p 1 90 30 ,5 p 1 90 31 p 1 90 32 p 2 16 38 p 2 16 -4 1 n c e q q m o n o c ri st a lli n o 1 3 ,6 1 8 ,1 1 3 ,0 1 1 ,2 1 1 ,6 1 6 ,3 1 5 ,4 1 7 ,1 1 3 ,1 1 7 ,8 1 8 ,5 1 5 ,6 1 3 ,3 1 8 ,4 q p o lic ri st a lli n o a t e ss it u ra g ro s. 1 ,6 2 ,8 2 ,0 1 ,6 1 ,3 1 ,3 1 ,3 0 ,3 0 ,6 3 ,3 2 ,6 1 ,2 3 ,0 1 ,6 q p o lic ri st a lli n o a t e ss it u ra f in e 0 ,9 1 ,3 1 ,0 1 ,0 0 ,3 1 ,0 0 ,9 1 ,5 0 ,9 0 ,8 2 ,3 0 ,6 1 ,7 0 ,3 s e lc e 0 ,6 0 ,3 0 ,3 0 ,3 0 ,6 0 ,6 1 ,7 1 ,4 1 ,5 0 ,3 q in f .r . p lu to n ic o -g n e is si c a 0 ,6 1 ,3 1 ,0 1 ,6 1 ,3 0 ,3 1 ,2 0 ,6 1 ,4 1 ,4 0 ,6 0 ,7 0 ,3 q in f .r . m e ta m o rf ic a 0 ,7 0 ,3 0 ,3 0 ,6 0 ,6 0 ,9 0 ,3 q in f .r . vu lc a n ic a q in f .r . c la st ic a 3 ,8 0 ,6 1 ,3 1 ,3 1 ,0 2 ,3 0 ,3 1 ,8 0 ,9 1 ,1 1 ,2 1 ,8 1 ,0 0 ,3 f k m o n o c ri st a lli n o 0 ,6 2 ,0 3 ,6 5 ,1 6 ,8 3 ,1 3 ,0 3 ,0 3 ,3 0 ,3 4 ,8 0 ,7 3 ,9 k in f .r . p lu to n ic o -g n e is si c a 0 ,7 1 ,6 1 ,0 0 ,9 0 ,3 0 ,9 0 ,3 0 ,3 k in f .r . m e ta m o rf ic a k in f .r . vu lc a n ic a k in f .r . c la st ic a 0 ,3 0 ,3 p m o n o c ri st a lli n o 1 5 ,2 1 7 ,2 1 4 ,3 9 ,9 1 3 ,5 1 1 ,1 9 ,1 1 2 ,5 1 3 ,7 1 8 ,9 2 0 ,2 1 2 ,9 1 5 ,0 1 0 ,7 p in f .r . p lu to n ic o -g n e is si c a 1 ,3 0 ,7 0 ,7 0 ,6 0 ,7 0 ,3 2 ,1 1 ,2 0 ,8 2 ,6 1 ,8 0 ,7 1 ,3 p in f .r . m e ta m o rf ic a 0 ,3 0 ,3 p in f .r . vu lc a n ic a p in f .r . c la st ic a 1 ,6 1 ,0 0 ,3 0 ,3 0 ,3 0 ,6 0 ,9 0 ,3 0 ,7 l l it ic o m e ta m o rf ic o 0 ,6 0 ,3 0 ,7 0 ,9 0 ,6 0 ,6 0 ,3 l it ic o v u lc a n ic o 0 ,0 l it ic o ip o a b is sa le 0 ,3 1 ,6 2 ,3 0 ,3 1 ,3 0 ,3 0 ,6 1 ,8 0 ,6 0 ,8 0 ,9 0 ,6 1 ,0 0 ,3 s p ili te 0 ,9 0 ,0 0 ,7 1 ,0 0 ,7 0 ,6 0 ,6 0 ,3 0 ,6 0 ,3 0 ,3 s e rp e n ti n it e 1 ,3 2 ,2 2 ,3 2 ,3 0 ,6 0 ,3 0 ,3 4 ,3 0 ,3 1 ,7 1 ,7 0 ,3 1 ,3 l it ic o c la st ic o s h a le 9 ,5 8 ,8 8 ,5 6 ,9 8 ,7 6 ,2 6 ,6 6 ,4 9 ,1 8 ,4 5 ,2 5 ,4 6 ,3 1 0 ,4 s ilt it i 7 ,3 8 ,1 1 4 ,3 1 2 ,5 1 2 ,5 1 0 ,4 9 ,7 1 0 ,7 1 0 ,1 6 ,4 1 0 ,4 1 0 ,2 1 0 ,0 9 ,4 m ic h e e c lo ri ti m o n o c ri st a lli n e 1 ,3 2 ,2 0 ,7 0 ,3 0 ,3 0 ,9 0 ,3 0 ,3 2 ,8 0 ,6 0 ,3 m ic h e e c lo ri ti in f .r . 0 ,3 m in e ra le p e sa n te m o n o c ri st 0 ,3 0 ,7 m in e ra le p e sa n te in f .r . o ss id i f e rr o 0 ,3 0 ,3 0 ,3 c e c c a lc it e s p a ti c a 1 9 ,9 1 5 ,3 1 6 ,9 1 5 ,8 1 6 ,7 1 7 ,3 2 3 ,6 1 3 ,1 1 9 ,8 1 4 ,2 1 2 ,1 1 7 ,1 2 1 ,3 1 4 ,6 c a lc a re s p a ti c o 5 ,1 4 ,4 2 ,9 7 ,6 4 ,5 3 ,6 4 ,1 3 ,0 4 ,3 1 ,9 3 ,8 5 ,1 8 ,0 5 ,8 c a lc a re im p u ro 2 ,5 1 ,3 1 ,6 2 ,3 1 ,3 1 ,6 1 ,6 2 ,4 5 ,5 1 ,9 1 ,4 2 ,4 2 ,0 2 ,9 m u d st o n e -w a c ke st o n e 1 1 ,1 1 4 ,4 1 5 ,0 1 8 ,8 1 5 ,8 1 5 ,3 1 8 ,6 1 4 ,6 1 1 ,6 9 ,7 1 0 ,7 1 5 ,0 1 3 ,0 1 7 ,8 p a c ks to n e -g ra in st o n e b io c la st o ( te rr ig e n o ) 0 ,3 0 ,3 0 ,9 0 ,6 0 ,3 0 ,6 n c i a lt ri n c i (la te ri zi ) c i b io c la st o ( p e n e c o n te m p o ra n e o ) a lt ri c i (c a lc in e lli ) g ra n o in d e te rm in a to 0 ,3 0 ,6 0 ,9 1 ,2 0 ,3 t o ta le 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 composizione dei sedimenti sabbiosi ... 386 t a b . 1 , p a g . 2 c o m p o si zi o n e m o d a le d e i c a m p io n i a n a liz za ti p re le va ti d a lle p e rf o ra zi o n i t a v . m o d al c o m p o si ti o n o f sa n d s fr o m t h e s tu d ie d w e lls a lo n g t h e t a v t ra c k. p 2 4 -3 2 p 2 4 -3 5 p 2 7 -1 4 p 2 7 -1 6 p 2 7 -1 8 p 2 7 -2 5 p 2 7 -2 6 p 2 7 -2 7 p 2 7 -2 9 p 2 7 -3 1 p 2 7 -3 3 p 2 7 -3 5 p 2 7 -3 7 p 2 7 -4 1 p 2 7 -4 9 n c e q q m o n o c ri st a lli n o 1 8 ,4 1 6 ,4 1 0 ,8 1 3 ,5 1 5 ,4 1 5 ,8 1 5 ,5 1 6 ,3 2 0 ,3 2 4 ,2 1 7 ,6 1 8 ,6 1 5 ,8 2 6 ,0 2 6 ,5 q p o lic ri st a lli n o a t e ss it u ra g ro s. 1 ,4 3 ,2 1 ,5 2 ,4 1 ,3 5 ,0 1 ,8 3 ,3 4 ,3 2 ,7 5 ,8 2 ,5 2 ,3 2 ,4 2 ,2 q p o lic ri st a lli n o a t e ss it u ra f in e 1 ,9 1 ,4 0 ,9 1 ,2 0 ,6 1 ,6 3 ,3 2 ,4 1 ,8 1 ,5 1 ,2 0 ,3 0 ,6 2 ,4 0 ,3 s e lc e 1 ,1 0 ,9 0 ,6 1 ,2 0 ,3 1 ,5 0 ,3 0 ,3 0 ,3 1 ,2 0 ,6 1 ,2 0 ,9 q in f .r . p lu to n ic o -g n e is si c a 0 ,3 0 ,9 1 ,5 0 ,6 0 ,6 1 ,6 1 ,5 2 ,1 0 ,9 1 ,8 1 ,8 0 ,3 0 ,6 0 ,3 1 ,5 q in f .r . m e ta m o rf ic a 1 ,1 0 ,6 0 ,3 1 ,3 0 ,3 0 ,3 0 ,6 0 ,6 1 ,5 0 ,0 0 ,3 0 ,0 q in f .r . vu lc a n ic a 0 ,3 0 ,3 0 ,3 0 ,0 0 ,0 q in f .r . c la st ic a 1 ,4 1 ,7 1 ,8 2 ,1 1 ,0 1 ,6 0 ,3 0 ,9 0 ,9 1 ,2 1 ,8 1 ,5 1 ,9 0 ,9 0 ,9 f k m o n o c ri st a lli n o 6 ,5 6 ,6 0 ,3 1 ,9 8 ,5 2 ,4 6 ,2 8 ,3 5 ,2 2 ,4 3 ,5 1 ,2 2 ,8 k in f .r . p lu to n ic o -g n e is si c a 1 ,1 1 ,2 0 ,6 0 ,9 0 ,3 0 ,3 0 ,6 0 ,3 0 ,6 k in f .r . m e ta m o rf ic a k in f .r . vu lc a n ic a 0 ,3 k in f .r . c la st ic a 0 ,3 0 ,6 0 ,0 0 ,6 p m o n o c ri st a lli n o 7 ,9 1 0 ,1 1 4 ,8 1 0 ,7 1 5 ,4 1 0 ,7 1 8 ,8 1 4 ,5 1 8 ,5 1 0 ,0 1 9 ,1 1 4 ,9 1 0 ,6 1 9 ,0 1 6 ,7 p in f .r . p lu to n ic o -g n e is si c a 1 ,1 1 ,2 1 ,5 1 ,6 1 ,6 2 ,4 2 ,4 1 ,8 2 ,1 1 ,2 1 ,9 2 ,3 2 ,4 1 ,2 p in f .r . m e ta m o rf ic a p in f .r . vu lc a n ic a p in f .r . c la st ic a 0 ,6 0 ,9 0 ,9 0 ,6 0 ,3 0 ,9 0 ,6 1 ,2 0 ,6 0 ,9 0 ,6 0 ,6 0 ,9 l l it ic o m e ta m o rf ic o 0 ,8 0 ,3 0 ,3 0 ,3 0 ,9 0 ,6 0 ,6 0 ,9 0 ,3 0 ,3 0 ,6 0 ,6 0 ,3 l it ic o v u lc a n ic o 0 ,3 0 ,6 l it ic o ip o a b is sa le 1 ,6 0 ,3 0 ,3 0 ,6 0 ,3 0 ,9 0 ,6 0 ,9 1 ,5 0 ,6 0 ,9 0 ,3 0 ,6 1 ,8 0 ,3 s p ili te 0 ,5 0 ,6 0 ,3 0 ,9 0 ,3 0 ,9 0 ,3 0 ,6 0 ,9 s e rp e n ti n it e 1 ,1 1 ,4 0 ,3 0 ,6 0 ,6 1 ,3 0 ,9 0 ,9 1 ,2 1 ,2 1 ,5 1 ,9 1 ,0 0 ,3 0 ,3 l it ic o c la st ic o s h a le 7 ,0 2 ,9 8 ,0 6 ,7 5 ,1 8 ,5 4 ,0 6 ,2 4 ,3 4 ,2 7 ,0 7 ,7 4 ,2 2 ,8 6 ,2 s ilt it i 1 0 ,8 1 1 ,0 1 1 ,1 9 ,8 1 1 ,9 6 ,6 1 0 ,0 8 ,6 6 ,8 8 ,8 6 ,4 7 ,1 8 ,4 7 ,3 7 ,1 m ic h e e c lo ri ti m o n o c ri st a lli n e 0 ,3 1 ,2 0 ,6 0 ,6 1 ,3 0 ,9 1 ,2 0 ,3 0 ,3 0 ,3 2 ,5 m ic h e e c lo ri ti in f .r . 0 ,3 0 ,3 0 ,3 0 ,3 m in e ra le p e sa n te m o n o c ri st 0 ,5 0 ,3 0 ,3 0 ,3 0 ,3 m in e ra le p e sa n te in f .r . 0 ,3 0 ,3 o ss id i f e rr o 0 ,8 0 ,3 0 ,3 0 ,6 0 ,6 0 ,3 0 ,3 0 ,3 0 ,3 c e c c a lc it e s p a ti c a 1 4 ,9 1 6 ,4 1 8 ,2 1 7 ,4 1 8 ,3 7 1 3 ,2 1 3 ,4 1 3 ,1 1 0 ,2 1 2 ,1 1 5 ,2 1 4 ,6 1 7 ,7 1 1 ,6 1 3 ,9 c a lc a re s p a ti c o 5 ,7 5 ,2 4 ,9 5 ,2 3 ,5 4 ,1 5 ,5 5 ,0 2 ,8 3 ,3 3 ,3 5 ,6 4 ,2 2 ,4 3 ,1 c a lc a re im p u ro 1 ,9 1 ,2 4 ,3 3 ,1 3 ,2 3 ,2 3 ,6 3 ,9 2 ,5 3 ,3 2 ,7 1 ,9 1 ,3 2 ,1 1 ,2 m u d st o n e -w a c ke st o n e 1 1 ,4 1 5 ,3 1 7 ,5 2 0 ,8 1 6 ,1 9 ,8 1 1 ,9 8 ,6 7 ,7 1 1 ,2 8 ,8 1 4 ,9 2 0 ,6 1 1 ,0 8 ,0 p a c ks to n e -g ra in st o n e b io c la st o ( te rr ig e n o ) 0 ,5 0 ,6 0 ,3 0 ,6 0 ,6 0 ,9 0 ,6 0 ,3 0 ,6 0 ,6 0 ,9 n c i a lt ri n c i (la te ri zi ) c i b io c la st o ( p e n e c o n te m p o ra n e o ) a lt ri c i (c a lc in e lli ) g ra n o in d e te rm in a to 0 ,3 0 ,3 0 ,3 0 ,9 0 ,3 0 ,3 0 ,6 0 ,3 0 ,9 0 ,3 t o ta le 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 s. lugli et al. 12 ka (fig. 11) non ricade all’interno dei campi composizionali individuati per i corsi d’acqua attuali, ma si allinea in posizione intermedia rispetto ai campi composizionali del grizzaga, del secchia e dell’unità di vignola (pleistocene sup.). come si può notare nella tab. 1, tali campioni sono caratterizzati da un contenuto in granuli feldspatici (13,5-30,8 %) maggiore rispetto a quelli dei corsi d’acqua attuali (6,9-21,3 %). 387 fig. 10 composizione dei campioni prelevati nelle perforazioni tav con età minore di 10-12 ka. nel diagramma sono indicati i campi composizionali delle sabbie attuali e recenti (neolitico) dei corsi d’acqua modenesi. composition of samples from tav wells with an age younger than 10-12 kyr. the diagram shows also the compositional fields of modern and recent (neolithic) sands of the modena plain streams. fig. 11 composizione dei campioni prelevati nelle perforazioni tav con età maggiore di 1012 ka. nel diagramma sono indicati i campi composizionali delle sabbie attuali e recenti (neolitico) dei corsi d’acqua modenesi e dell’unità di vignola (pleistocene sup., presso formigine). composition of samples from tav wells with an age older than 10-12 kyr. the diagram shows also the compositional fields of modern and recent (neolithic) sands of the modena plain streams and of the vignola unit (late pleistocene, close to formigine). composizione dei sedimenti sabbiosi ... 388 3.3. discussione dei dati composizionali i dati composizionali suggeriscono che l’alluvionamento recente della media pianura modenese, di età inferiore a circa 12 ka, sia stato prevalentemente effettuato dai corsi d’acqua minori, mentre i fiumi maggiori, secchia e panaro, probabilmente contribuivano alla sedimentazione attraverso deposizione di sedimenti fini. il rinvenimento di sabbie non attribuibili ai due fiumi maggiori nel sottosuolo in prossimità del loro attuale letto sembra confermare l’ipotesi che i tracciati del secchia e panaro abbiano iniziato a convergere nella zona a nord della città soltanto in epoca piuttosto recente, come evidenziato dalla distribuzione delle tracce dei paleoalvei ancora visibili in superficie (gasperi & pizziolo, in stampa). altro dato significativo riguarda il torrente tiepido le cui sabbie presentano una composizione del tutto caratteristica e che non sono state identificate nel sottosuolo della media pianura. l’ipotesi più probabile è che anche in passato, così come oggi, esso confluisse nel panaro a monte dell’area esaminata. i campioni prelevati al di sotto dei livelli torbosi riferibili ad un’età di circa 12 ka evidenziano una situazione complessa. le sabbie hanno una composizione particolare, spostata verso il vertice quarzo-feldspati, che non ha corrispondenza con le petrofacies individuate per le sabbie oloceniche e attuali dei corsi d’acqua modenesi. in particolare, come evidenziato in precedenza, le sabbie risultano arricchite in feldspati. la spiegazione di tale composizioni non è semplice. queste sabbie appartengono probabilmente ad un ciclo sedimentario più antico rispetto a quello per il quale è stata dimostrata la validità del nostro schema interpretativo, basato sulla composizione dei sedimenti olocenici ed attuali (lugli et al., 2003). le differenze composizionali riscontrate possono essere indotte da variazioni nella natura dei litotipi affioranti nel bacino di alimentazione, e potrebbero essere collegate all’erosione di successioni terrigene a composizione francamente arcosica, come quelle presenti in successioni torbiditiche del cretaceo superiore di unità liguri interne, o ad unità epiliguri ricche in feldspati. l’erosione di porzioni di formazioni geologiche di composizione diversa rispetto a quelle attualmente affioranti potrebbe inoltre essere il risultato di variazioni nello sviluppo ed estensione del reticolo idrografico. la variazione composizionale dei sedimenti trasportati dai corsi d’acqua potrebbe essere imputata a mutamenti climatici legati ai cicli glaciale-interglaciale in grado di indurre variazioni nell’entità e modalità dei fenomeni di alterazione ed erosione del substrato (effetto climatico). altro fattore che può aver contribuito alla differenziazione composizionale riscontrata nei sedimenti deposti intorno a 10-12 ka sono le alterazioni diagenetiche, che potrebbero aver in parte modificato i granuli di sabbia in condizioni di seppellimento. tali effetti però non hanno modificato in misura importante i sedimenti fluviali olocenici (lugli et al., 2003). i fenomeni diagenetici nelle sabbie oloceniche consistono infatti prevalentemente nella formazione di concrezioni carbonatiche, e non possono quindi essere responsabili di arricchimenti in feldspati, minerali ritenuti particolarmente labili in tali condizioni diagenetiche. non ultimo, il riciclo di successioni sedimentarie più antiche potrebbe aver contribuito alla produzione di sedimenti a composizione diversa rispetto a quelli oggi deposti. tali fenomeni di riciclo dovevano comunque coinvolgere sedimenti caratterizzati da un contenuto in feldspati maggiore di quello attuale. le differenze composizionali osservate tra la porzione superiore e quella inferiore della successione studiata indicano cambiamenti drastici nel contesto geografico, ambientale e deposizionale, avvalorando l’ipotesi di una significativa discontinuità stratigrafica tra le due porzioni. 4. conclusioni le perforazioni tav hanno permesso di evidenziare come la sedimentazione fluviale nella media pianura modenese sia drasticamente mutata a partire da circa 10-12 ka. la composizione dei sedimenti sabbiosi più recenti sembra ricalcare quella dei corsi d’acqua minori che attraversano oggi la pianura nel tratto compreso tra i fiumi secchia e panaro. i sedimenti sabbiosi più antichi di circa 10-12 ka presentano invece composizioni diverse, arricchite in feldspati. queste differenze composizionali possono riferirsi a combinazioni di vari fattori quali: a) variazioni nella litologia del substrato per fenomeni tettonici e/o per variazioni nello sviluppo del reticolo idrografico, b) fenomeni di riciclo di sedimenti fluviali antichi. l’arricchimento in feldspati che caratterizza queste sabbie rende improbabili effetti di alterazione per variazioni climatiche e/o modificazioni diagenetiche post-deposizionali. i dati composizionali acquisiti, la distribuzione dei sedimenti sabbiosi lungo la sezione studiata ed il confronto con le stratigrafie oloceniche e tardo-pleistoceniche in settori più prossimali (area urbana di modena e alta pianura) suggeriscono che tra i sedimenti tardo-pleistocenici e quelli olocenici sia presente una significativa discontinuità stratigrafica di importanza regionale. i nuovi dati composizionali in corso di acquisizione e le datazioni assolute attualmente in via di realizzazione permetteranno di ottenere nuove informazioni utili per interpretare l’evoluzione spaziale e temporale dei corpi fluviali nel sottosuolo della pianura modenese. ringraziamenti questo lavoro non sarebbe stato possibile senza la disponibilità delle ditte operanti nei cantieri della tav. un ringraziamento al consorzio cepav uno e in particolare a maria de vita per la gentilezza e la disponibilità dimostrata. un ringraziamento a mariangelo baio e renzo valloni per le preziose informazioni e il diretto aiuto sul terreno. riferimenti bibliografici amorosi a. & farina m. (1994) sequenze deposizionali nei depositi alluvionali quaternari del primo sottosuolo nell'area a est di bologna, tra il t. savena e s. lugli et al. 389 il t. idice 1st. european congress on regional geological cartography and information systems. bologna, june 13-16, 5, pp. 35-54. amorosi a. & farina m. (1995) – large-scale architecture of a thrust-related alluvial complex from subsurface data: the quaternary succession of the po basin in the bologna area (northern italy) giorn. di geol., ser. 3, 57 (1/2), pp. 3-16. amorosi a., farina m., severi p., preti d., caporale l. & di dio g. (1996) genetically related alluvial deposits across active fault zones: an example of alluvial fan-terrace correlation from the upper quaternary of the southern po basin, italy sedim. geol., 102, pp. 275-295. cibin u. & di giulio a. (1996) proposta per l’analisi microscopica della composizione delle areniti nell’ambito della carta geologica d’italia boll. serv. geol. d’italia, cxv, pp. 87-98. cremaschi m. & gasperi g. (1989) l’alluvione alto medioevale di mutina (modena) in rapporto alle variazioni ambientali oloceniche mem. soc. geol. it., 42, pp.179-190. dickinson w.r. (1970) interpreting detrital modes of graywacke and arkose journ. sedim. petrology, 40, pp. 695-707. fazzini p. & gasperi g. (1996) il sottosuolo della città di modena accad. naz. sci. lett. arti di modena miscellanea geologica, 15, pp. 41-54. gasperi g., cremaschi m., mantovani uguzzoni m.p., cardarelli a., cattani m. & labate d. (1989) evoluzione plio-quaternaria del margine appenninico modenese e dell'antistante pianura. note illustrative alla carta geologica mem. soc. geol. it. 39, pp. 375-431. gasperi g. & pizziolo m. (in stampa) note illustrative della carta geologica d’italia a scala 1:50.000. foglio 201 “modena” regione emilia-romagna servizio geologico d’italia. gazzi p. (1966) le arenarie del flysh sopracretaceo dell’appennino modenese; correlazioni con il flysh di monghidoro miner. petrogr. acta, 12, pp. 69-97. houghton h.f. (1980) refined techniques for staining plagioclase and alkali feldspars in thin section journ. sedim. petrology, 50, pp. 629-631. howarth r.j. (1998) improved estimators of uncertainity in proportions, point-counting and pass-fail test results am. journ. of science, 298, pp. 594607. lugli s., marchetti dori s. & fontana d. (2003) composition of fluvial sands as a tool to unravel the recent sedimentation history of the modena plain (northern italy) abstract: 22nd ias meeting of sedimentology, opatjia (croatia), 17-19 september 2003, abstracts book, p. 11. pellegrini m. & zavatti, a. (1979) le falde acquifere della pianura a sud del fiume po, tra i fiumi enza e panaro genio rurale, 42, 5. regione emilia-romagna & eni-agip (1998) riserve idriche sotterranee della regione emilia-romagna (a cura di di dio g.). s.el.ca. (firenze) pp. 120. valloni r., baio m. & bedulli f. (2003) architettura deposizionale del pleistocene superiore nel sottosuolo della media pianura emiliana riassunti convegno fist geoitalia 2003, bellaria,16-18 settembre 2003, pp.125-127. media print, livorno. zuffa g.g. (1985) optical analyses of arenites: influence of methodology on compositional results in (a cura di g.g. zuffa) “provenance of arenites”. nato asi series, reidl publishing company, 148, pp. 165-189. ms. ricevuto l’11 maggio 2004 testo definitivo ricevuto il 18 agosto 2004 ms. received: may 11, 2004 final text received: august 18, 2004 composizione dei sedimenti sabbiosi ... amq_28(2) cop e sn 12_2015.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 28 (2), 2015, iii vi in memory of alfredo bini giuseppe orombelli with the help of luisa zuccoli, valter maggi and andrea zerboni department of environmental and earth sciences – university of milano-bicocca, italy corresponding author: g. orombelli <giuseppe.orombelli@unimib.it> there are always sentiments of sadness and regret in remembering those, old masters or colleagues, who have left us, but it is especially sad and moving in commemorating colleagues and friends younger than we are, who have suddenly and unexpectedly departed, leaving in those who remain the painful and unforeseen absence of a person with whom we have shared years, interests, passions, topics of research and discussion. alfredo bini suddenly died on 30 april 2015, in the department of earth sciences of the university of milan, while preparing with the colleagues field excursions for the students. on thinking of his demise, recollections accumulated with the passing of time re-emerge to suggest where to start in a commemoration that would not be a mere, brief description of alfredo bini's scientific results. alfredo bini on a field geological campaign on lake garda with a group of students (courtesy of l. zuccoli) in a short note it is quite difficult to fully and properly describe the amount of work done by alfredo, now to be found in over three hundred of his publications, and come up with the most significant ones. alfredo bini was born in cairo on 8 january 1948. in october 1973, he received his degree in medicine in milan and began a brilliant career as a researcher in the biomedical field. in the years 1974 and 1975, with a grant from the italian national research council, he worked at the pharmacology institute of the university of milan and published the results of his studies with his co-workers in prominent international scientific journals. but for some time his interests were focused on an entirely different world: that of karst caves. as a student, and up to his graduation, he had already published nineteen papers on caves and added another dozen while performing his post-graduate work in pharmacology. i cannot recall the year, but it was around 1975 or 1976, when alfredo appeared before me saying that he wanted to matriculate in geology because he wanted to study caves scientifically and full time as a geologist. i imagine that i tried to dissuade him: leaving such an important scientific sector in which he had already worked so brilliantly for one with few job opportunities seemed to be a folly. i am sure i also said that at that time the institute of geology in milan had no scientific interest in speleology. but then i saw alfredo's character, firm and decided, and i should add obstinate, if this adjective did not have a prevalently negative connotation. alfredo graduated as a geologist in february 1982, with a thesis entitled “geologia e geologia del glaciale del monte san primo” (geology and glacial geology of mount san primo). he had been obliged to accept another subject of study, but at least it was in the area of como's prealps, where he knew every cave and ravine. thus alfredo began his studies on glacial deposits, which he never abandoned, as well as those on subterranean karst and speleogenesis, even trying to connect them. he was admitted to post-graduate courses and received his doctorate in 1987, with a dissertation entitled: "l'apparato glaciale würmiano di como" (the würmian glacial system of como). in the meantime, forging ahead in the same year, he became an associate professor of physical geography (with tenure starting from 1988) in the degree course of geological sciences of the university of milan, thanks to the research activities he had been performing for more than a decade. in his cv he had some eighty papers, mostly on the subject of speleology, but also a few on the quaternary and geomorphology of the como region, among which the note prepared together with m.b. cita and m. gaetani on the hypothesis of the origin of the italian prealpine lakes in connection with the messinian salinity crisis (1978). those were the times! in those years the increase in the number of students made possible the creation of new chairs in the different disciplines and the entry of new professors. in this position of total autonomy alfredo developed his research. starting from his dissertation on the como glacial deposits, he began a systematic survey of the quaternary deposits of the large piedmont glacier systems, from that of verbano to that of garda and then expanded into the prealpine and alpine environments. through a reflection on the stratigraphic criteria applicable to quaternary continental deposits and their experimentation, alfredo bini has certainly made a great contribution to the affirmation in recent italian official geological cartography of the unconformity -bounded stratigraphic units, introduced to provide major objectivity and ductility in the survey of continental deposits, also in response to the acknowledged multiplicity of glacial and interglacial climatic cycles and minor glacial oscillations. these criteria, still in the process of being more accurately defined, were used by bini in the geological map of the province of bergamo at the scale of 1:50,000, published in the year 2000. in his monograph of 2001, “geologia del mendrisiotto (messiniano, pliocene, quaternario)” (geology of the mendrisio region messinian, pliocene and quaternary) with a 1:25,000 geologic map, he clearly delineated the methods he used, described the recognized units and reconstructed the subsequent phases of glacial expansion, with sketches and detailed maps. bini, together with other quaternary scientists, made numerous contributions to the definition of the guidelines and rules for the surveying of quaternary continental deposits for the italian geological service. geological mapping experiments at the scale of 1:10,000 in different prealpine and alpine contexts, as part of the “cartografia geologica (carg)” project, preceded the systematic surveys for the sheets of the 1:50,000 italian geological map. alfredo bini was the director (or supervisor) of surveys on the neogene-quaternary units of as many as eleven 1:50,000 geological maps, from the piedmont to the alpine sectors of lombardy. it is known that the new italian 1:50,000 maps have led to a decisive reassessment of quaternary continental deposits, in the sense that much attention has been devoted to them. they are no longer considered an indistinct cover hiding the bedrock, but rather a complex and sensitive skin, varied and rich in geological information of scientific as well as practical interest. there has been a consequent explosion of units that have been recognized and mapped in the different main watersheds. while this allowed to obtain a much greater detail and objectivity (with advantages in knowledge and proper land use), it has also created difficulties in chronological and stratigraphic iv orombelli g. attributions, correlations and syntheses. the complexity of stratigraphic relations between the different units can be seen for example in a schematic drawing in the lower margin of sheet 099 iseo of the 1:50,000 geological map, which shows graphically and concisely the unconformity-bounded units, the discontinuity surfaces that delimit them, their lithology and morphology. on the iseo sheet, mainly representing a prealpine mountainous area, about sixty bedrock units and forty continental neogene and quaternary units have been mapped. on the nearby clusone sheet, thirty -three bedrock units and sixty units of surficial continental deposits have been mapped. of these, forty-two are attributed to the quaternary and eighteen are considered of mio-pliocene age. and we could continue in this way. in the illustrative notes, the chapters on the surficial deposits are just as voluminous, if not more so, than those devoted to the bedrock units. in more recent years, bini took an interest in the morphology and quaternary deposits in the high alpine valleys as well, in particular in valtellina and val chiavenna, on topics such as the lateglacial, the holocene glacier fluctuations, the deep-seated gravitational slope deformations, the evolution of the relief and so on. it is easy to foresee that the knowledge alfredo accumulated on quaternary deposits and glacial history of the vast sector of the alps he studied and surveyed will remain for a long time as a construction that cannot be overlooked by those who wish to continue these studies. the mass of analytical data that he systematically collected and described awaits a synthesis, which alfredo has several times outlined and progressively implemented: only advances of knowledge and of dating techniques will allow to complete this work. together with his research and interests in the evolution of lombardy's territory in the quaternary, and in particular the reconstruction of the many glacial cycles and phases, alfredo kept alive his passion and study of subterranean karst, especially in the como prealps. if at the beginning his production covered different topics of speleology, ranging from exploration, to morphology, mineralogy, biology, meteorology and so on, his investigations gradually became more sharply focused on the genesis of caves, their relationship with surface karst features and the evolution of regional geomorphology. to be remembered in particular are his studies, together with other colleagues, on the geochemistry and dating of cave concretions, which are important in many fields, such as neotectonic studies. his attention was attracted especially by the karst morphology of the grigne group /(lecco). his monograph on the moncodeno karst is memorable, but these few lines are not sufficient to give a true idea of how much he produced in this sector. i shall cite just one final review paper by several authors on a subject that alfredo studied for many years. i refer to the article by dubois et al. (2014) that appeared recently in earthscience reviews “the process of ghost-rock karstification and its role in the formation of cave systems”. in this article, the development of subterranean karst systems appears not to take place by means of a single process of gradual and total removal through dissolution of carbonate rocks. there is a great deal of field evidence which instead shows a two-stage process, similar to that of deep weathering and denudation acting on insoluble rocks (e.g. granitoids). the first stage is thought to be deep chemical weathering by dissolution of the more soluble components which leaves a “ghost rock” (alterite) made of the less soluble components, separated from the unaltered rock by a sharp weathering front. the second stage, which involves increased energy of the system, is thought to lead to mechanical erosion of the “ghost rock”. this is a new hypothesis which certainly finds corroboration in contexts of impure carbonate rocks such as the moltrasio limestone in the como region, a deeply karstified thick well-bedded formation of clayey-siliceous limestone. alfredo bini also took to heart his teaching and the dissemination of scientific information, with textbooks and popular science writings. it was in his nature to surround himself with friends and organize groups, to urge his students on through his love for his studies and his overflowing cheerfulness. those who knew him still can hear his strong, solid voice and his disarming and loud laugh. i do not know the exact number, but i believe that alfredo assigned and supervised a huge number of fieldgeology master and phd thesis, carefully checking the geologic mapping, with great commitment and assiduity. in the most touching tribute at the last farewell at mandello, on 2 may 2015, with alfredo’s photographs shown in sequence on a screen (he was an excellent photographer of landscapes and portraits), his thoughts, his poems (yes, beautiful poems i would never have imagined it!) and the testimonials of his friends, his wife luisa read a passage from le città invisibili (invisible cities) by italo calvino, one that he loved and that reflects his way of conducting research. here is the passage translated from the italian: marco polo describes a bridge, stone by stone. “but which is the stone that supports the bridge?" kublai khan asks. “the bridge is not supported by one stone or another," marco answers, "but by the line of the arch that they form.” kublai khan remains silent, reflecting. he then adds: “why do you speak to me of the stones? it is only the arch that matters to me.” polo replies: “without stones there is no arch.” i recall that the classic textbook géologie stratigraphique by gignoux (the father of the calabrian v alfredo bini stage), on which the geologists of my generation studied, had at the beginning of the foreword this sentence (in italian): un fatto è come un sacco: vuoto, non si regge. perché si regga, bisogna prima farci entrar dentro la ragione pirandello, sei personaggi in cerca d’autore (a fact is like a bag: empty it cannot stand. so that it can stand it must first be filled with reason – pirandello, six characters in search of an author). stratigraphy is certainly based on the collection of facts, but for them to stand they need an idea that supports them, that holds them together. this was the task that alfredo assigned to himself: that of a slow, tenacious, relentless constructor: the choice of the stones, one by one, to build a bridge that stands. thank you and farewell, alfredo. ms. received: november 16, 2015 final text received: november 19, 2015 vi alfredo bini at work on the alps (courtesy of l. zuccoli) orombelli g. amq sn 1 falcucci pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 27 (1), 2014, iii viii report on the 2014 aiqua summer school “la geologia del quaternario applicata allo studio delle faglie attive: dai terremoti alla microzonazione sismica” emanuela falcucci, stefano gori, and the 2014 aiqua summer school participants * istituto nazionale di geofisica e vulcanologia, l’aquila corresponding author: e. falcucci <emanuela.falcucci@ingv.it > abstract: we here summarise the activities carried out during the 2014 aiqua summer school, held from the 29th of september to the 3rd of october at istituto nazionale di geofisica e vulcanologia (ingv) of l’aquila, and supported by ingv-progetto abruzzo. the school aimed at highlighting the major contribution of quaternary geological investigation to the analysis of active and capable faults: this approach involves seismotectonic analysis and surface faulting hazard assessment on faults and deep seated gravitational slope deformations. the participants attended two days of classes, related to those topics, held by experts, and actively and largely joined the discussions raised during the lessons; furthermore, they took part to a three-day fieldtrip in the 2009 l’aquila earthquake area and surroundings. concepts and methods learned during the lessons were applied to selected case studies: these included the 2009 l’aquila earthquake causative fault and other major active normal faults affecting the gran sasso range and the middle aterno river valley. moreover, participants actively took part in still ongoing paleoseismological investigations that aimed at the reconstruction of the recent kinematic behaviour and slip history of the assergi fault, a major active normal fault of the central apennines. keywords: quaternary geology, active and capable faulting, deep seated gravitational slope deformation, paleoseismology, surface faulting hazard, seismic microzonation. active and capable faults and large scale gravitational slope deformations represent geological criticalities that, as elements of surface fragility, can interfere with human development; they must therefore be taken into consideration for seismotectonic analysis and, consequently, for a proper land use planning. these topics were discussed during the 2014 aiqua summer school concerning, in particular, investigation methodologies and hazard assessment. the school took place in the abruzzi region, at the istituto nazionale di geofisica e vulcanologia in l’aquila, from the 29th of september to the 3rd of october. an appreciable number of “students” attended the event: undergraduates and ph.d. students, postdoctoral fellows, researchers and freelance geologists, from central and southern italy, and one coming from great britain. during the first two days, lessons were held by experts in active tectonics, quaternary geology, paleoseismology, neotectonics, earthquake geology, seismic microzonation. they lectured with laudable enthusiasm (and without remuneration!). they held high-value classes and stimulated discussion among the participants on the different topics mentioned above, some of which are presently a matter of debate in the scientific community, especially with regard to surface faulting hazard assessment. the speakers thoroughly emphasised the importance of “old-school” geological survey, which lays the foundation for a multi-methodological approach in active and capable faulting analyses. we warmly thank all the lecturers for their irreplaceable contribution to the success of the school! monday, september 29 the first day of the school was opened by dr. andrea sposato who, as a senior member of aiqua, spoke on behalf of aiqua itself, thanking all of the participants and lecturers for taking part to the summer school; he emphasised the importance of such events in increasing the awareness of the fundamental role of quaternary geology in active tectonics analysis, especially as for young scientists and students. then, the ingv-progetto abruzzo was presented by its scientific coordinator dr. gianluca valensise who, together with ingv-l’aquila branch manager, dr. fabrizio galadini, supported the aiqua event. after these introductive talks, a series of scientific classes began with dr. paolo messina, who illustrated general aspects of quaternary geological investigations and their contribution to the reconstruction of tectonic and paleoenvironmental history of the central apennines. dr. fabrizio galadini gave a lecture on the role of quaternary geological investigations on active and capable faulting studies; his lesson was also dedicated to the definition of time intervals to assess the notion of “active and capable faults” for engineering practices in * domenico berti, fabrizio brutto, tamara carducci, antonio cefalì, edi chiarini, silvia crosetto, fabrizio cultrera, paolo di marcantonio, federica durante, pasquale evangelista, giandomenico fubelli, biagio giaccio, michele lancia, francesca liberi, lorenzo lo sardo, serena madonna, gianmarco mondati, marco moro, giuseppe napoli, francesco pavano, michele saroli, stefania silvestri, andrea sposato, fabrizio tinelli, domenico trotta italy. dr. daniela pantosti focused on general and methodological aspects of paleoseismological analysis, showing several case studies all over the world, and highlighting the effectiveness of such investigations for seismic hazard assessment. dr. gianluca valensise illustrated the italian database of individual seismogenic sources (diss); he also showed some examples of peculiar geological features that mimic active faulting, and other cases where the relation between active faults at surface and seismogenic structures at depth can be complicated by the inheritance of older tectonic structures. ing. maria basi explained the role and task of the abruzzi region local government in the seismic microzonation studies of the whole region (fig. 1a). dr. paolo boncio gave a lecture on the criteria to define zones of surface fault-rupture hazard; he illustrated the new guidelines – currently underway – for surface fault rupture zonation in italy that are still a matter of interest and debate within the italian scientific community and the italian governmental institutions. dr. paolo galli illustrated the state of the art of paleoseismological investigations in italy, showing some recent examples of such analyses along italian major active normal faults. dr. alberto pizzi showed the most recent outcomes of ongoing seismic microzonation studies of the town of facucci e. & gori s. iv fig. 1 lessons held during the first two days of the summer school; a) ing. maria basi illustrates microzonation studies presently ongoing in the abruzzi region, b) dr. marco moro shows the re-activation of large scale gravitational slope deformation during the 1997 colfiorito earthquake. fig. 2 fieldtrip – visit to the paleoseismological trenches dug across the assergi fault. v report on the 2014 aiqua summer school fig. 3 fieldtrip – moments of the lunch at campo imperatore, waiting for “arrosticini” to be cooked. fig. 4 fieldtrip – the group discusses on the campo imperatore active fault strands. mt. brancastello in background, through the clouds. sulmona, in the abruzzi region: he outlined the geological factors that influence local seismic response and the issue of active and capable faulting affecting the sulmona territory. tuesday, september 30 the second day of lessons began with dr. marco tallini, who illustrated the results of seismic microzonation studies carried out in l’aquila after april, 2009, in the difficult post-earthquake framework; he examined all of the geological complexities needed to be understood and unraveled. dr. nicola tullo showed the role of freelance geologists in the ongoing seismic microzonation studies in the abruzzi region. dr. marco moro gave two lectures: the former about general aspects of deep seated gravitational slope movements and their relation with active tectonics; the latter focused on the use of satellite radar interferometry and paleoseismological techniques to investigate the kinematic behaviour and mechanics of large scale gravitational mass movements. he showed different case studies of large scale mass wasting that had been reactivated during large magnitude seismic events occurred in italy during the past decades (among which the 2009 l’aquila earthquake) (fig. 1b). dr. stefano gori illustrated, through case studies selected over the central apennines, the role of quaternary geological field analysis in demonstrating the inactivity of tectonic structures despite the presence of misleading morphological hints suggesting activity. the last talks introduced the fieldtrips: dr. biagio giaccio reported a comprehensive picture of the quaternary geological evolution of the paganica village area where, the activation of the normal fault causative of the 2009 earthquake caused surface fault rupture. dr. emanuela falcucci illustrated the quaternary geological evolution of the middle aterno river valley and of the subequana valley, and their relation with the long term kinematic evolution of the active normal faults that affect the eastern borders of these intermontane depressions. dr. stefano gori and dr. marco moro illustrated the present knowledge about the activity of the assergicampo imperatore fault system, where paleoseismological trenches, shown during the first day of the fieldtrips, have been dug. they also showed the structural and tectonic complexities that characterise the southwestern flank of the gran sasso range, resulting from the interference between active extensional faults and inactive thrust faults inherited by the presently inactive compressive regime. wednesday, october 1 on the first day, the fieldtrip was spent along the assergi active normal fault. two paleoseismological trenches dug across the central part of the fault – made ad-hoc for the summer school – were visited. the walls of the excavations were observed, analysing evidence of the recent fault movements and searching for elements that give information about its slip history (fig. 2). we moved, then, to the fossa di paganica tectonic depression, located along the southern portion of the assergi fault. here, geomorphological evidence of the recent activity of the tectonic structures was analysed in the light of the results coming from paleoseismological investigations, which were recently performed along this part of the fault (moro et al., in prep.). after a wonderful and pleasant lunch, where the participants experienced and made practice in the art of cooking “arrosticini” (accompanied by more than one glass of red wine!!) (fig. 3), the fieldtrip continued in campo imperatore highland, specifically focusing on glacial and peri-glacial deposits exposed along the plain and on the active normal faults pattern that affects the area (fig. 4). during the last part of the afternoon, some of the closed tectonic depressions that characterise the southwestern flank of the gran sasso range were visited, with a particular focus on the bounding fault scarps; the evidence of recent activity of these structures was discussed, together with their tectonic “significance” in the complex structural framework of the mountain front. furthermore, geomorphic evidence of the occurrence of large scale gravitational slope deformation along the gran sasso southwestern flank was shown. thursday, october 2 the first half of the fieldtrip on the second day was led along the paganica fault, whose activation determined the april 6, 2009 seismic event. in particular, the vi fig. 5 fieldtrip – dr. biagio giaccio describes middle pleistocene tephra layers contained in alluvial sediments displaced by the paganica fault. facucci e. & gori s. site of the water main that had been damaged by the fault activation was visited, analysing the quaternary (and late pleistocene-holocene) deposits displaced by some secondary fault planes exposed along the main fault scarp, in the area of paganica. evidence of activation of the paganica fault during seismic events preceding the 2009 one was examined. alluvial fan and fluvial deposits containing middle pleistocene tephra layers and displaced along the fault were analysed in detail (fig. 5). during the afternoon, a fault plane exposed at the southern termination of the paganica fault, in poggio picenze, was observed, described and analysed; the structure brings into contact lacustrine and alluvial deposits. then, evidence for the late quaternary activity of one of the northernmost segments of the middle aterno valley fault was illustrated near corbellino: fluvial-lacustrine deposits are affected by a complex shear zone, synthetic to the main fault scarp; as a consequence of the fault movement, they were placed in contact with slope deposits. the day ended with beers, teas, juices, snacks and laughters in san demetrio ne’ vestini. friday, october 3 the last fieldtrip focused on the middle aterno valley-subequana valley fault system. the participants enjoyed a wonderful panoramic view of the scarp of the roccapreturo fault segment from the village of goriano valli (fig. 6). the roccapreturo fault scarp is one of the most impressive fault scarplets of the central apennines. evidence for the quaternary and late pleistoceneholocene activity of the roccapreturo segment was illustrated and described in more detail in the village of roccapreturo: there, the tectonic structure brought in to contact the carbonate bedrock, cropping out on the footwall, with late pleistocene-holocene deposits, exposed at the base of the fault scarp. the stop was followed by the description of the quaternary morpho-stratigraphic and tectonic evolution of the subequana valley. in particular, some fault planes related to the subequana valley fault were shown in the vii report on the 2014 aiqua summer school fig. 6 fieldtrip – dr. emanuela falcucci describes the middle aterno valley fault system. fig. 7 fieldtrip – dr. giandomenico fubelli describes one of the active fault plane that crosses castelvecchio subequo. area of castelvecchio subequo (fig. 7). evidence of the displacement of middle pleistocene fluvial deposits and of late pleistocene slope sediments along these faults were analysed in detail. the organisers emanuela falcucci and stefano gori warmly thank all the participants for the days spent together and for the more than pleasant company! everyone was extremely friendly, active and interested, and the mood was always overjoyed and superb!! the organisers consider the summer school experience as extremely positive, a cultural and human growth, and they hope this will not be the last “stop” but the first of many other similar initiatives !! viii facucci e. & gori s. ms. received: october 26, 2014 final text received: november 16, 2014 ix imp. bizzarri & ll’’aaffffiioorraammeennttoo ddeell ccaaiioo ((llaaggoo ddii ccoorrbbaarraa,, oorrvviieettoo,, iittaalliiaa cceennttrraallee)) nneellll’’aammbbiittoo ddeellll’’eevvoolluuzziioonnee ppaalleeooggeeooggrraaffiiccaa pplliioo –– pplleeiissttoocceenniiccaa ddeellllaa vvaallllee ddeell tteevveerree:: eevviiddeennzzee sseeddiimmeennttoollooggiicchhee ee ssttrraattiiggrraaffiicchhee rroobbeerrttoo bbiizzzzaarrrrii11**,, ppiieerrlluuiiggii aammbbrroosseettttii11****,, ppaattrriizziiaa aarrggeennttii11******,, ggiiaaccoommoo ddiieeggoo ggaattttaa22 && aannggeellaa bbaallddaannzzaa11******** 1dipartimento di scienze della terra, università di perugia, p.zza università, 1, 06100 perugia, *roberto.bizzarri@libero.it, **pambrose@unipg.it, ***biogeo@unipg.it, ****abaldanz@unipg.it 2bayerisches geoinstitut, universität bayreuth, universität strasse, 30 d95447 bayreuth, germany, diego.gatta@uni-bayreuth.de riassunto l’affioramento del caio (lago di corbara, orvieto, italia centrale), per i suoi peculiari caratteri sedimentologici e stratigrafici, suggerisce un riesame del contesto paleoambientale e paleogeografico dell’area durante il pliocene superiore – pleistocene inferiore. l’affioramento, situato a circa 6 km dall’abitato di corbara, mostra una successione di depositi marini e continentali del pliocene medio – superiore e pleistocene inferiore, passanti da sabbie, a sabbie argillose, ad argille e infine a ghiaie, riferibili alle unità delle “sabbie a flabellipecten” e delle “argille e sabbie del chiani – tevere” (ambrosetti et al., 1987). la parte finale della successione, affiorante all’interno di una piccola cava, è costituita da diversi corpi ghiaiosi, che sono stati interpretati come depositi della parte medio prossimale di un conoide alluvionale, probabilmente deposti in un breve intervallo temporale. sia nelle argille che nelle ghiaie sono state inoltre rinvenute piroclastiti. e’ stata effettuata sia un’analisi di facies che uno studio biostratigrafico; inoltre, i campioni contenenti materiale vulcanoclastico sono stati oggetto di indagini mineralogico cristallochimiche, eseguite in diffrattometria a raggi-x da polveri e in microscopia elettronica a scansione (sem-eds). il rinvenimento di hyalinea balthica e nannoplancton calcareo del pleistocene inferiore basale all’interno di depositi riferibili alle “argille e sabbie del chiani – tevere”, il ritrovamento di piroclastiti a probabile affinità toscana, ed infine la presenza di depositi continentali di età confrontabile con quella delle argille forniscono nuovi dati utilizzabili per la ricostruzione dell’evoluzione paleogeografica dell’area durante il pliocene superiore – pleistocene inferiore abstract the caio outcrop (corbara lake, orvieto, central italy) in the plio – pleistocene palaeogeographic evolution of tiber valley: sedimentological and stratigraphical evidences. the caio outcrop (corbara lake, orvieto, central italy) suggests a re-evaluation of the palaeoenvironmental and palaeogeographical scenery during the late pliocene – early pleistocene induced by its peculiar sedimentological and stratigraphical feature. the outcrop is located about 6 km from the corbara village, and shows a succession of marine and continental deposits, varying from sands, to clayey sands, to clay and finally to gravels. the latest part of caio succession, made of several gravel bodies, outcrops into a small abandoned quarry. both clay and gravel bodies contain pyroclastic material. a facies analisys, based on sedimentological and palaeontological features, and a biostrathigraphic study have been made; moreover , the samples with volcanoclastic material were object of sem – eds analisys and x-ray diffrattometry for mineralogical and petrological determination. on the basis of paleontological content, the sand sediments (from 0 m to 15 m) are referred to the “sabbie a flabellipecten” unit (ambrosetti et al., 1987) for the presence of pecten (flabellipecten) flabelliformis (brocchi) in assemblage with common amphistegina sp. and benthic microforaminifers typical of detritical environments (conti et al., 1983). the overlaying clayey sand sediments (from 15 m to 17.5 m), in spite of the lack of flabellipecten, for their macropaleontological content, with no particular variation in respect to underlying sands, are here related to “sabbie a flabellipecten” unit; however, some problems still remain about their stratigraphical attribution. the following (from 17.5 m to 23 m) clay sediments are instead referred to the “argille e sabbie del chiani – tevere” unit (ambrosetti et al., 1987). the presence of amusium sp., globorotalia inflata (d’orbigny), common bulimina marginata and b. elegans, gephyrocapsa oceanica, helicosphaera sellii and calcidiscus macintyrei allows the identification of early pleistocene age; this age attribution is supported by the finding of hyalinea balthica from 19.50 m. the pliocene – pleistocene boundary is hypothetically placed at 18.50 m, in the lower part of clay sediments. the gravel bodies (from 23 m to 29 m) are interpreted as middle – proximal alluvial fan deposits, probably deposited over a short time period. their age attribution is still an open problem, but some considerations could be made: 1) the reworked microfossil assemblages contain only middle pliocene – early pleistocene specimens, accompained by h. balthica; 2) the younger clastic components of gravel bodies come from middle – upper pliocene biocalcarenites (amphistegina level sensu conti et al., 1983); 3) the pyroclastites, found from 17.5 m to 29 m, contain the same pyroxenes not altered with typical habitus, showing no or only little abrasion; 4) on the basis of preliminary mineralogical and petrological data, it is possible to make some generalizations on the affinity of the volcanic products with the neighbouring magmatic provinces (hks-roman comagmatic province; ksmonti vulsini, roccamonfina, ventotene; tuscan magmatic province; ulud-umbria-latium ultra-alkaline district). the presence of ortopyroxenes suggest, for at least part of the pyroclastites, a tuscan affinity and consequently an older age. on the other hand, our geological study suggests the probable existence of small eruptive centres in the vicinity; 5) a reworked mollusc assemblage, recorded in the middle-upper part of the caio outcrop, is composed of poor littoral marine and freshwater species, the last ones referable to the early pleistocene. these considerations, although a middle pliocene age is not totally rejectable, allow the hypothesis of an early pleistocene age (upper emiliano siciliano) for alluvial – fan deposits, with the consequence of a minimal age gap in respect to the underliyng marine clay sediments. thus, caio’s gravel bodies could be considered as heteropical to upper part of “argille e sabbie del chiani – tevere” unit. in this way, the upper portion of caio outcrop, still marking a local paleoenvironmental situation, testifies the great lateral variability of early pleistocene deposits, referable to “argille e sabbie del chiani – tevere” unit. could be ipotized a coastal morphology articulation, somehow inherited but surely exasperated by strong tectonics at pliocene – pleistocene boundary: this tectonic phase, with structural axes striking ne – sw to e w, displaced pliocene deposits, that were partially reworked, causing a lateral environmental variability, testified by facies heteropy. in a similar scenery, with clay testifying marine environments of increasing depth from east to west, alluvial – fan complexes, as caio alluvial fan, took place, draining sw or nw and partially reworking different deposits of the same marine basin in which they came, during a regressive phase of marine level. parole chiave: sedimentologia, stratigrafia, conoide alluvionale, pliocene, pleistocene, piroclastiti, umbria occidentale. keywords: sedimentology, stratigraphy, alluvial fan, pliocene, pleistocene, pyroclastites, western umbria. il quaternario italian journal of quaternary sciences 1166(2), 2003, 241-255 242 r. bizzarri et al. 11.. iinnttrroodduuzziioonnee dalla seconda metà degli anni settanta fino agli inizi degli anni novanta l’area è stata oggetto di studio per le sue implicazioni nell’evoluzione dell’italia centrale durante il pliocene ed il pleistocene (ambrosetti et al., 1977; 1978a), sia in chiave neotettonica e geomorfologica (ambrosetti et al., 1978b; cattuto et al., 1979), che stratigrafica (ambrosetti et al., 1987). dai lavori citati emerge una ricostruzione evolutiva abbastanza ben delineata nelle sue linee principali, ma anche un’estrema variabilità nelle caratteristiche dei singoli affioramenti, espressione di numerose, e spesso poco note, situazioni locali (bizzarri, 2001). l’affioramento del caio presenta delle peculiarità, sia dal punto di vista sedimentologico e stratigrafico, che per la presenza di intercalazioni piroclastiche, che lo rendono interessante sia in chiave di interpretazione paleoambientale, sia nell’ottica di una ricostruzione evolutiva dell’area. con questa finalità si è tentato un approccio sedimentologico, tramite analisi di facies, per ricostruire le caratteristiche paleoambientali, affiancato da un’analisi biostratigrafica di dettaglio, tramite foraminiferi planctonici e bentonici, nannoplancton calcareo e malacofaune, che ha permesso di inquadrare cronologicamente la successione. i campioni provenienti dalla porzione terminale, contenenti materiali piroclastici, sono stati oggetto di analisi mineralogico – petrografica tramite microscopia elettronica a scansione (sem – eds) e diffrattometria a raggi – x. appare già chiaro, nonostante gli studi siano ancora in una fase preliminare, come questa situazione getti una nuova luce sia sulla variabilità dei paleoambienti pleistocenici nell’area in esame, sia sull’evoluzione paleoambientale tra il pliocene superiore ed il pleistocene inferiore. 22.. iinnqquuaaddrraammeennttoo ggeeoollooggiiccoo ddeellll’’aarreeaa ssttuuddiiaattaa l’affioramento in oggetto è situato nei dintorni di orvieto (fig. 1), nell’umbria occidentale, circa 6 km a nw dell’abitato di corbara. sul versante collinare in sponda sinistra del f. paglia a quota 200 m s.l.m. è situata una piccola cava di ghiaia; da qui parte una carreggiabile che scende in modo graduale, portando, dopo un paio di chilometri, a guadare il f.so del caio. la successione risulta esposta anche a seguito del terrazzamento operato dal f. paglia in tempi recenti. la valle del paglia è stata storicamente interpretata come un graben (funiciello et al., 1981; aa.vv., 1982), delimitato da sistemi di faglie dirette, ad andamento appenninico, attivi probabilmente fin dal pliocene inferiore. un ulteriore sistema di faglie a prevalente carattere estensionale, ad andamento anti appennico, comprendente tra l’altro la vicina faglia all’interno della gola del forello, ne interrompe la continuità, creando un insieme di blocchi, variamente dislocati. questo articolato quadro tettonico probabilmente ha determinato, localmente, movimenti compressivi e/o trascorrenti in un contesto complessivamente estensionale. l’attività tettonica (ambrosetti et al., 1977; 1978b; cattuto et al., 1979; 1988) si articola in varie fasi: come detto, durante il pliocene inferiore l’azione di faglie dirette creò dei bacini, come appunto la valle attualmente occupata dal basso corso del f. paglia, fortemente subsidenti, dove si impostarono ambienti marini da costieri a relativamente profondi. tra il pliocene medio – superiore e, probabilmente, il pleistocene inferiore, una ripresa dell’attività tettonica determinò un’articolazione ancora più marcata dei paleoambienti, con evidenze di variazioni laterali di facies da francamente continentali, salmastre fino a marine. nell’area del caio, i depositi pliocenici e pleistocenici sono riferibili, rispettivamente, alle unità delle “sabbie a flabellipecten” e delle “argille e sabbie del chiani – tevere” (ambrosetti et al., 1987). 33.. ccaarraatttteerrii sseeddiimmeennttoollooggiiccii ee ssttrraattiiggrraaffiiccii ddeellll’’aaffffiioorraammeennttoo la successione plio – pleistocenica del caio poggia in discordanza su terreni di età miocenica rappresentati nella fattispecie da corpi “torbiditici”. la successione può essere seguita con continuità per uno spessore di circa 30 m, la maggior parte dei quali visibili come taglio stradale; gli ultimi 6 m affiorano invece nella parete di una cava dismessa. nel dettaglio, è costituita da sabbie con intercalazioni ciottolose (spessore circa 15 m), passanti a sabbie argillose (3 m circa), seguite da argille (5 m circa) e ghiaie (6 m, parete di cava). il contatto argille – ghiaie, visibile alla base del piano di cava, è di natura chiaramente erosiva. la parete della cava (fig. 2) si estende in direzione n – s per circa 30 m ed ha un’altezza di 6 m; la sua continuità è interrotta da due piani di taglio, con componente inversa, immergenti verso nord, che rialzano (rigetto apparente circa 50 cm) il blocco settentrionale. mancano completamente dei marker cinematici misurabili, così come una sezione ortogonale alla parete di cava, che permettano di stabilire con precisione l’entità reale del rigetto. sono inoltre ben visibili corpi ghiaiosi con caratteristiche diverse. i corpi sabbiosi alla base della successione e le argille possono essere riferiti rispettivamente alle “sabbie a flabellipecten” e alle “argille e sabbie del chiani – tevere” (ambrosetti et al., 1987); di incerta attribuzione restano al momento le sabbie argillose, interposte tra le due suddette unità, così come i corpi ghiaiosi della cava. le prime sono state riferite alle fig. 1ubicazione dell’affioramento del caio. location of caio outcrop. “sabbie a flabellipecten”, mentre i secondi meritano alcune riflessioni, che sono riportate nel capitolo conclusivo. nella descrizione sedimentologica è stata utilizzata la scala granulometrica proposta da blair & mcpherson (1999) e riportata in tabella 1. ssaabbbbiiee aa ffllaabbeelllliippeecctteenn sabbie con ciottoli la parte inferiore della successione (fig. 3) è costituita nei primi 7 – 8 m da sabbia media – fine (ms), localmente cementata, da sabbia fine (fs) nei metri successivi, per uno spessore complessivo di ~15 m. il colore è giallo ocra, mentre i singoli granuli, da subangolosi a subarrotondati, ad alto sorting, sono in prevalenza frammenti litici, tra cui dominano carbonati e selci. sono presenti numerose intercalazioni ciottolose, con tre differenti tipologie: corpi lenticolari, non ben definiti, costituiti da elementi con diametro 2÷8 mm (classi granulometriche g e fp), presenti in tutto il livello: lo spessore è sempre modesto (max 10 cm), mentre lo sviluppo laterale è variabile. livelli a geometria piano – convessa, con spessore nella parte centrale 10 cm max, larghi poche decine di centimetri, costituiti da granuli (g), con un abbozzo di laminazione (presenti tra il metro 2,5 e il metro 3). livelli a base erosiva, con geometria lenticolare, spessore e persistenza variabili, con gradazione diretta, sia in senso verticale che laterale: la granulometria passa infatti da fp a g. litologia (litotipi carbonatici con subordinate areniti nella classe fp, prevalenza di selce nella classe g) ed arrotondamento (elementi da subarrotondati a molto arrotondati, ad eccezione della selce che appare sempre da subangolosa ad angolosa) sono elementi tessiturali comuni a tutte le intercalazioni ciottolose. si rinvengono frequenti ostreidi di grandi dimensioni ed altri bivalvi prevalentemente integri, insieme ad accumuli locali di frammenti. questo livello suggerisce la sedimentazione in un ambiente marino costiero poco profondo, riferibile ad una shoreface superiore; i materiali più grossolani almeno in parte sembrano testimo243l’affioramento del caio ... niare una rielaborazione ad opera del moto ondoso (dune sottomarine), anche se non si escludono apporti fluviali. la presenza di pecten (flabellipecten) flabelliformis (brocchi), associato a comuni esemplari di amphistegina sp. e foraminiferi bentonici tipici di substrati detritici (conti et al., 1983), ne consente l’attribuzione alle “sabbie a flabellipecten” (ambrosetti et al., 1987). sabbie argillose a diretto contatto con il livello precedente, si trovano sabbie molto fini, limoso – argillose (vfs/m) per uno spessore di circa 3 m. il colore è giallo, e le caratteristiche tessiturali sono le stesse descritte per lo spessore sottostante, ad eccezione della granulometria e dell’assenza di intercalazioni ciottolose. sono frequenti, invece, accumuli di gusci frammentati, in una matrice di sabbia molto grossolana (vcs); comuni sono anche locali associazioni di ostreidi, cementati gli uni sugli altri. la documentazione paleontologica appare molto più evidente di prima, e compaiono frequenti microresti vegetali. l’ambiente deposizionale, marino costiero con apporti continentali, e la costanza faunistica, malgrado l’assenza di p. (flabellipecten) flabelliformis, suggeriscono una continuità deposizionale rispetto alle sottostanti sabbie, durante un trend regressivo. pertanto, questi depositi sono riferiti alle “sabbie a flabellipecten”. aarrggiillllee ee ssaabbbbiiee ddeell cchhiiaannii –– tteevveerree argille tra il livello precedente ed i corpi ghiaiosi visibili nella parete di cava sono presenti ~ 5 m di argille limose (m), grigiastre, prive di strutture macroscopiche, ma contenenti sia un’abbondante fauna marina che numerosi microresti vegetali. sono soprattutto questi ultimi caratteri, come verrà meglio esposto nel paragrafo successivo, che ci permettono di attribuirle ad un ambiente francamente marino, ma con apporti continentali di carattere distale. da segnalare la presenza di macrocristalli di pirosseno, non rielaborati né frammentati. ddeeppoossiittii ddii ccoonnooiiddee affiorano come parete di cava, sono separati dalle fig. 2 porzione superiore dell’affioramento del caio. la parete di cava misura 30 m in larghezza e 6 m in altezza, sviluppandosi in direzione n-s (nord a sinistra nella foto). la continuità della parete è interrotta da due piani di taglio con componente inversa, immergenti circa verso nw; il rigetto apparente è di circa 50 cm. sono visibili corpi ghiaiosi e sabbiosi con caratteristiche differenti, complessivamente interpretati come depositi di conoide alluvionale. gmc = ghiaia non organizzata; gp = ghiaia a stratificazione incrociata; sh = sabbia argillosa a laminazione piano parallela; sp = sabbia a laminazione incrociata. upper portion of the caio outcrop. the quarry front is 30 m width and 6 m high, and oriented n-s (north on the left in the photo). the front continuity is broken off by two reverse – fault planes, dipping nw, for a total dislocation of 50 cm. are clearly visible several gravel and sand bodies, with different characters, interpreted as alluvial fan deposits. gmc = disorganized gravel; gp = planar cross – stratified gravel; sh = laminated claiely – sand; sp = planar cross – laminate sand. 244 sottostanti argille da un chiaro contatto erosivo, parzialmente visibile a livello del piano di escavazione, e sono costituiti da corpi con caratteristiche diverse. alternanze ciottoli sabbia la porzione basale della parete di cava (fig. 4) è caratterizzata dall’alternanza di corpi ghiaiosi, abbastanza organizzati, e sabbie a laminazione incrociata. entrambi mostrano geometrie lenticolari, tanto da interdigitarsi reciprocamente. i corpi ghiaiosi, clast – supported, hanno geometria lenticolare e sono abbastanza ben organizzati. i ciottoli, di forma piatta o allungata, da sub – arrotondati a molto arrotondati (arrotondamento da 0,5 a 0,9), hanno dimensioni max di 12 cm, con media intorno ai 5 cm: rientrano pertanto nella classe dei vcp. i clasti sono in netta prevalenza di natura carbonatica (micrifig. 3 successione stratigrafica del caio (parte inferiore). 1 = argilla; 2 = sabbia argillosa; 3 = sabbia; 4 = sabbia con ciottoli; 5 = ghiaia matrice – sostenuta; 6 = livelli cementati; 7 = gasteropodi marini; 8 = glycimeris sp; 9 = flabellipecten flabelliformis; 10 = chlamys spp; 11 = amusium sp; 12 = ostrea spp; 13 = cerastoderma edule; 14 = anadara spp; 15 = dentalium spp; 16 = briozoi; 17 = coralli; 18 = serpulidi; 19 = radioli di echinidi; 20 = burrows di crostacei; 21 = chele di crostacei; 22 = denti di pesci; 23 = frustoli vegetali; 24 = foraminiferi planctonici; 25 = miche; 26 = pirosseni. caio stratigraphic section (lower portion). 1 = clay; 2 = claiely sand; 3 = sand; 4 = gravelly sand; 5 = matrix – supported gravels; 6 = cemented levels; 7 = marine gastropods; 8 = glycimeris sp; 9 = flabellipecten flabelliformis; 10 = chlamys spp; 11 = amusium sp; 12 = ostrea spp; 13 = cerastoderma edule; 14 = anadara spp; 15 = dentalium spp; 16 = briozoa; 17 = corals; 18 = serpulids; 19 = echinoidal radioles; 20 = crustacean (burrows); 21 = crustacean (pincers); 22 = fish teeths; 23 = frustoles; 24 = planctonic foraminifers; 25 = micas; 26 = pyroxenes. r. bizzarri et al. 245 fig. 4 successione stratigrafica del caio (parte superiore). 1 = argilla; 2 = sabbia; 3 = sabbia con ciottoli; 4 = ghiaia clasto – sostenuta; 5 = ghiaia matrice – sostenuta; 6 = livello pedogenizzato non organizzato; 7 = pirosseni; 8 = miche; 9 = pomici; 10 = scorie; 11 = gasteropodi dulcicoli; 12 = natica sp; 13 = unio sp. caio stratigraphic section (upper portion). 1 = clay; 2 = sand; 3 = gravelly sand; 4 = clast – supported gravel; 5 = matrix – supported gravel; 6 = not organized pedogenetic level; 7 = pyroxenes; 8 = micas; 9 = pumices; 10 = scoriae; 11 = freshwater gastropodes; 12 = natica sp; 13 = unio sp. ti e calcareniti della scaglia s.l., calcareniti della marnoso arenacea), ma sono presenti anche areniti, provenienti da formazioni mioceniche della serie umbra o toscana, quarzoareniti di provenienza non chiara (simili ad “anageniti minute” del verrucano toscano) e calcareniti provenienti da corpi parzialmente cementati di età pliocenica (livello ad amphistegina sensu conti et al., 1983). i ciottoli appaiono di colore rosso e/o ocra per la presenza di una patina di ossidi, e sono associati ad una matrice di vcs/g, in cui sono abbondanti macrol’affioramento del caio ... 246 cristalli di pirosseno e proietti piroclastici della taglia dei lapilli. i ciottoli appaiono chiaramente isorientati, disposti con l’asse aa ortogonale al fronte della cava ed il piano aa-bb immergente verso monte, secondo un’embriciatura da corrente, del tipo aa((tt)) bb((ii)). sembra possibile definirli come facies gm (miall, 1982). ai ciottoli si alternano lenti di sabbia ciottolosa, molto grossolana fino a passare ai granuli (vcs/g), a sorting medio – alto (σ = 0,80 – 1,40 ϕ); i singoli elementi, da subarrotondati ad angolosi (arrotondamento da 0,20 a 0,40), sia ad alta che a bassa sfericità, sono in prevalenza frammenti litici di composizione carbonatica, associati a cristalli di quarzo, feldspato e calcite, con frazioni subordinate di pirosseni ad habitus prismatico, di colore verde scuro o nero. sono molto rare le pomici, mentre nella taglia dei granuli sono comuni frammenti di selce. le lenti sabbiose mostrano, localmente, più o meno evidenti laminazioni incrociate a set tabulari, tanto da poterle definire come facies sp (miall, 1982). le alternanze tra facies gm e sp sono interpretate come depositi da sheetflood (blair & mcpherson, 1994). argille sabbiose al tetto dell’alternanza ghiaie – sabbie è presente un livello costituito da argilla limoso – sabbiosa (m/vfs), che può essere designato come facies sh (miall, 1982). si sviluppa per uno spessore massimo di 30 cm ed appare discontinuo. il colore è prevalentemente grigio – verde, ma piccole variazioni cromatiche mettono in evidenza una laminazione ondulata parallela; anche la base del livello appare ondulata. la frazione più grossolana ha rivelato, all’esame microscopico, la prevalenza di frammenti litici a composizione carbonatica, ad alto sorting, elevata sfericità e di forma prevalentemente subarrotondata; questi sono accompagnati da macrocristalli di pirosseno, lamelle di mica e rare pomici. assente la malacofauna, la documentazione micropaleontologica è costituita da qualche ammonia e rari foraminiferi planctonici rimaneggiati. livelli ghiaiosi non organizzati livelli di ciottoli grossolani (max 30 cm, media 16 cm: fc/mc) sono presenti nella parte centrale della parete di cava. mostrano tessitura matrix – supported e sono privi di un’evidente organizzazione, se si esclude la presenza, localmente, di embriciature da flusso gravitativo, di tipo aa((pp)) aa((ii)): sono stati designati come facies gmc (orton, 1988). tra i ciottoli, prevalgono i litotipi carbonatici, associati ad areniti e a litoclasti argillosi. la forma varia con la litologia, ma i ciottoli appaiono in prevalenza ben arrotondati (arrotondamento 0,8 – 0,9). la matrice sabbiosa è molto grossolana (vcs/g), a sorting medio – alto (σ = 0,80 – 1,40 ϕ), arrotondamento da 0,20 a 0,40, e costituita da prevalenti elementi piroclastici (macrocristalli di pirosseno e pomici), con abbondante selce nella taglia dei granuli. si tratta di depositi legati all’azione di un processo di tipo gravitativo, presumibilmente un debris flow non coesivo, o grain flow (nemec & steel, 1984). ciottoli a stratificazione incrociata sempre nella porzione intermedia della parete di cava, si rinvengono due livelli ghiaiosi a stratificazione incrociata, clast – supported, a base erosiva, designati come facies gp (miall, 1982). la media dei ciottoli è intorno a 5 cm, con i clasti più grandi che arrivano a 10 cm (vcp); i litotipi mostrano la stessa associazione descritta in precedenza, sempre con dominanza degli elementi carbonatici. tutti i ciottoli presentano una patina di ossidazione superficiale, che penetra all’interno per alcuni mm, dando al livello un colore bruno – nerastro. la presenza di tale forma di alterazione lascia supporre periodi di esposizione subaerea. la matrice è costituita da sabbia molto grossolana/granuli (vcs/g) ad alto sorting (σ = 0,35 – 0,50 ϕ) ed arrotondamento da 0,20 a 0,40, composta in parti uguali da frammenti litici, pirosseni ad habitus prismatico e pomici. la matrice evidenzia la stratificazione incrociata a set tabulari delle ghiaie, mettendo in luce variazioni nell’inclinazione. si tratta in definitiva del riempimento multi – storey di canali, non molto profondi, dove l’azione di una corrente canalizzata, con buona competenza, si alternava a momenti di emersione del canale. la costruzione dei corpi ghiaiosi (“barre”) avveniva secondo il modello dei gravel sheets (hein & walker, 1977). all’interno del livello superiore si rinvengono frequenti gasteropodi, di dimensioni massime di 1 – 2 cm, ben conservati, sia dulcicoli che marini, accompagnati da individui interi e frammenti di lamellibranchi (unio sp.). sabbie a laminazione incrociata sabbie a gradazione diretta, con granulometria decrescente da media (ms) a fine (fs), identificabili come facies sp (miall, 1982), sono presenti nella parte alta della successione. il livello, di colore grigio e spessore variabile da 10 a 30 cm, con una notevole presenza di mica e pirosseni, mostra una laminazione incrociata a set tabulari ma con verso opposto. una simile situazione, di età diversa, ma con analoghe strutture viene illustrata nella sezione di torre del pagliaccetto (blanch, 1955; malatesta, 1978), dove viene interpretata come risultato di flussi piroclastici. ci sembra che tale interpretazione sedimentologica possa essere applicata anche nel nostro caso, sebbene l’argomento necessiti di ulteriori e più approfonditi studi. tab. 1 scala granulometrica utilizzata (da blair & mcpherson, 1999, ridis. e semplif.). adopted grain – size scale (from blair & mcpherson, 1999, redrawn). r. bizzarri et al. sabbie argillose la successione è chiusa da circa un metro di sabbie molto fini, limoso argillose (vfs/m), di colore giallo ocra e prive di organizzazione. la presenza di materia organica, di probabile origine vegetale, e di masserelle grigio – verdi di caco3, probabilmente calcinoli, lascia supporre che si tratti di un livello pedogenizzato non organizzato. 44.. aannaalliissii mmaaccrroo ee mmiiccrrooppaalleeoonnttoollooggiiccaa le litologie incoerenti (sabbie, argille sabbiose ed argille) sono state sottoposte a lavaggio con acqua ossigenata. il residuo di lavaggio è stato poi setacciato con maglie a luce netta da 125 µm e 63 µm. sono state osservate tutte le frazioni, da quelle maggiori di 125 µm fino a 63 µm; la componente al di sotto dei 63 µm si è rivelata sempre sterile. il contenuto microfossilifero è stato sottoposto ad un’analisi di tipo semiquantitativo i cui risultati sono riportati nelle tabelle 2 e 3. le litologie argillose sono state inoltre sottoposte ad analisi del contenuto di nannoplancton calcareo, tramite preparazioni di smear slides dal campione integro. l’analisi del nannoplancton calcareo ha rilevato la presenza, nel campione 10, di un’associazione a gephyrocapsa oceanica s.l. kamptner, calcidiscus macintyrei (bukry & bramlette) loeblich & tappan, helicosphaera sellii (bukry & bramlette) jafar & martini, coccolithus pelagicus (wallick) schiller. sia per la presenza del marker (zona a c. macintyrei) associato alla g. oceanica s.l., che per l’assenza di discoasteridi, è possibile riferire il campione 10 al pleistocene inferiore. l’associazione permane con abbondante c. macintyrei anche nel campione 11. come riportato da rio et al. (1997), la scomparsa di c. macintyrei, sincrona a livello mondiale, è riferibile a 1,45 – 1,46 ma. la presenza di tale specie nel nostro campione è ancora cospicua, e pertanto non dovremmo aver raggiunto questa età. la comparsa (fa) di g. oceanica s.l., per la nostra collocazione areale, deve essere considerata come quella del dsdp 132 (m. mediterraneo) e cioè variabile tra 1,56 – 1,62 ma. la concomitante presenza di g. oceanica s.l. e c. macintyrei ci indica un’età ipoteticamente compresa tra 1,62 – 1,46 ma oppure 1,56 – 1,45 ma. 44..11.. ccoommmmeennttii ssuullllaa mmiiccrrooffaauunnaa sulla base delle conoscenze delle faune bentoniche viventi nel mediterraneo e riportate da murray (1991) è possibile individuare caratteristiche associazioni con importanza paleoecologica utilizzabili per una ricostruzione paleoambientale. l’abbondanza del genere ammonia, fin dai campioni basali, indica un ambiente fortemente influenzato da una sedimentazione detritica. la microfauna planctonica fino al campione 8 è assente ad eccezione di rarissime forme di globigerinoides trilobus (reuss) ed orbulina universa d’orbigny rinvenute nel campione 2. le ammonie sono sempre accompagnate, anche come grado di frequenza, dal genere elphidium; a questi due generi si associa, anch’essa abbondante, asterigerinata planorbis (d’orbigny), confermando una situazione di mare poco profondo. la presenza in molti campioni della specie nonion depressulum (walker & jacob), riconosciuto come attualmente vivente nelle associazioni bentoniche che abitano gli ambienti iperalini, accompagnato da ammonia beccari (linnaeus), ci potrebbe fornire indicazioni indirette sulla condizione di salinità di queste acque costiere; la sua presenza infatti ci testimonia che i valori della salinità potevano essere localmente più elevati, forse legati ad una concentrazione di sali causata dall’evaporazione in stagni costieri o pozze d’acqua isolate dal mare da cordoni di sabbie. la variabilità composizionale delle associazioni rinvenute ci indica che nelle immediate vicinanze doveva esistere un collegamento con acque in condizioni più profonde e con valori nella norma marina di salinità. tale evidenza ci viene suggerita dalla abbondanza dei generi elphidium e quinqueloculina, cui si associa la forma erbivora cibicides lobatulus (walker & jacob). lo stile di vita attuale degli elphidium e delle quinqueloculine, che vivono attaccati ai rami delle posidonie, associato con la presenza di c. lobatulus, che vive sulle foglie ed è erbivoro, ci permettono di ipotizzare la presenza di praterie in cui queste forme epifite trovavano un habitat ideale. l’abbondanza inoltre di radioli di echinoidi, di chele di crostacei e di briozoi (spine e rami), abituali abitatori delle praterie a posidonie lungo costa e con fondali prevalentemente sabbiosi, ci confermerebbe un tale quadro paleoecologico. e’ stato rinvenuto anche il genere amphistegina, il cui unico rappresentante attuale, amphistegina madagascariensis d’orbigny (presente nel mediterraneo orientale), vive in habitat di praterie algali associata al genere ammonia. il genere amphistegina si trova abbondante in molti dei campioni analizzati, in cui si rinvengono forme di varia taglia non affetti da abrasione ed interi; questo fatto ci indica che esse vivevano in quell’ambiente, e non vi sono giunte per rielaborazione, probabilmente perché il loro stile di vita era epifita e sfruttavano anch’esse il substrato fornito dalle posidonie. bisogna ricordare a partire dal campione 11 (fig. 5) la presenza di hyalinea balthica (schroeter), tipico “ospite nordico”; tale forma viene riportata in letteratura (azzaroli et al., 1997) come evento caratteristico del pleistocene inferiore (emiliano), anche se la sua comparsa risulta diacrona nelle successioni proposte per la definizione del limite plio – pleistocene. il suo carattere spiccatamente indicativo di variazioni della paleotemperatura delle acque, ci permette di evidenziare un arrivo precoce di masse fredde sul versante paleotirrenico. la specie h. balthica viene attualmente riportata in adriatico come costituente della associazione a bulimina marginata d’orbigny (murray, 1991). concludendo, ci sembra corretto riferire il campione 10 (19 m) al santerniano, mentre il campione 11 (19,5 m) potrebbe essere riferito all’ emiliano basale. sembra inoltre possibile, pur se in via ipotetica, collocare il limite pliocene – pleistocene al metro 18,5 cioè tra i campioni 9 e 10 (fig.3). 44..22.. ccoommmmeennttii ssuullllaa mmaaccrrooffaauunnaa il contenuto macropaleontologico è sintetizzato in tab. 3. nei campioni fino al numero 12 la fauna a molluschi è analoga a quelle riportate nei lavori precedenti (ambrosetti et al., 1987; piccardi, 1994). da segnalare la presenza di pecten (flabellipecten) flabelliformis (brocchi) nel campione 5 e del genere amusium dal campione 8 in poi; nel campione 12 sono presenti due 247l’affioramento del caio ... 248 tab. 2 analisi semiquantitativa della microfauna del caio. (a= abbondante; f= frequente; c= comune; r= raro; p= presente) semiquantitative analysis of the caio section. (a= abundant; f= frequent; c= common; r= rare; p= present) r. bizzarri et al. 249 segue tab. 2 specie del genere chlamys. nei campioni 17 e 18 sono presenti solo molluschi dulcicoli (melanopsis sp., theodoxus sp., planorbis sp., succinea sp., unio sp.), riferibili genericamente ad un pleistocene inferiore (esu d., com. pers.), e qualche esemplare di natica sp. 55.. vvuullccaanniissmmoo eedd aassppeettttii mmiinneerraallooggiiccoo –– ppeettrrooggrraaffiiccii le indagini mineralogico petrografiche eseguite sui materiali appartenenti all’affioramento in esame evidenziano una complessa e articolata composizione geochimico – mineralogico petrografica dei depositi. nel corso dei precedenti paragrafi é stata evidenziata la presenza, dal metro 17,5 fino al tetto della successione, di due distinte famiglie di macrocristalli di pirosseni (con dimensioni fino a 8-10 mm), denominate “pirosseni verdi” e “neri”, le quali vengono sempre rinvenute insieme. le indagini mineralogico cristallochimiche, eseguite in diffrattometria a raggi-x da polveri e in microscopia elettronica a scansione (sem-eds) presso il laboratorio di cristallografia del bayerisches geoinstitut – universitat bayreuth, dimostrano che la famiglia dei “pirosseni verdi” é rappresentata da termini a composizione prevalentemente diopsidica (feo wt% 2%), mentre i “pirosseni neri” rappresentano i termini più augitici (feo wt% 10%). i fillosilicati segnalati (esclusa la frazione argillosa) sono sostanzialmente rappresentati da anniti biotiti e da qualche esemplare di muscovite. la componente feldspatica é rappresentata prevalentemente da k-feldspati (or 70-80). un approfondimento analitico é stato rivolto alle micropomici presenti nei campioni 17 e 18. tali pomici, che si rinvengono peraltro dal metro 25 al metro 28, hanno forma spigolosa, con dimensioni che raramente superano il millimetro, e mostrano solo minime evidenze di rielaborazione in ambiente alluvionale, indice di un trasporto limitato. le indagini effettuate in microscopia elettronica a scansione mostrano dei materiali estremamente variabili in termini di porosità, tessitura, composizione mineralogica. la figura 6a mostra un’immagine sem di una pomice relativa al campione 18. e’ evidente la presenza di due distinti litotipi. la parte superiore (frazione con più alta presenza di fasi cristalline) é caratterizzata dalla presenza di k-feldspati, na-plagioclasi, clinopirosseni augitici, alcuni ossidi (spinelli) e da una pasta di fondo vetrosa. la parte inferiore della pomice mostra la presenza di na-plagioclasi e di qualche cristallo di calcite, immersi in pasta di fondo vetrosa. dal punto di vista minerogenetico, é presumibile che il forte arricchimento in sodio dei plagioclasi (ab 70-85) sia un fenomeno secondario e che i cristalli di calcite rappresentino dei termini estranei all’assemblaggio mineralogico della roccia originaria (es. frammenti strappati da un eventuale condotto vulcanico, materiali saldati al frammento pomiceo all’impatto con il terreno, etc.). al campione 18 appartiene la pomice rappresentata nella figura 6b. in questo caso sono evidenti una diversa porosità ed una differente tessitura rispetto alla pomice rappresentata in figura 6a. la frazione cristallina é rappresentata da clinopirosseni (augitici) idiomorfi tozzi e aciculari immersi in una pasta di fondo vetrosa. sono abbondanti minerali secondari, come ad esempio nae ca-zeoliti. la figura 6c rappresenta l’immagine sem di una pomice appartenente al campione 17. sono evidenti alcuni fenocristalli di ortopirosseno enstatitico (analisi media: mgo 47.9%, feo 8.9%, cao 0.3%, sio2 42.9%), di clinopirosseno augitico e di na-plagioclasio. anche in questo caso sono presenti minerali zeolitici. i tre esempi di pomici appena descritti evidenziano un’articolata composizione mineralogico petrografica l’affioramento del caio ... dei materiali in esame. tale disomogeneità non consente di effettuare risolutivi confronti mineralogico petrografici con i litotipi delle province comagmatiche limitrofe all’area in esame (hks provincia comagmatica romana; ks m.ti vulsini, roccamonfina, ventotene; ulud distretto ultra alcalino umbro-laziale; provincia comagmatica toscana; poli, 1985; conticelli & peccerillo 1992; stoppa & lavecchia, 1992; peccerillo, 1998; 1999) allo scopo di stabilire eventuali relazioni e affinità. l’eccessiva alterazione dei vetri che costituiscono la pasta di fondo delle pomici, dimostrata dalla presenza di minerali zeolitici, comporta una diversissima composizione chimica evidente anche esaminando punti a distanza di pochi micrometri. la limitata quantità di campione a disposizione per ciascun tipo di pomice (ciascun individuo ha dimensioni inferiori al millimetro) non ha permesso di effettuare indagini, con un fondato significato statistico, sulla composizione chimica globale dei litotipi al fine di poter effettuare una classificazione petrologica. tuttavia, la presenza di ortopirosseni, riscontrata in diversi campioni pomicei, sembra suggerire un’affinità geochimica con la provincia toscana piuttosto che con le altre province magmatiche succitate, in cui gli ortopirosseni non sono mai stati segnalati. un particolare ritrovamento nel corso del rilevamento geologico ha suggerito la possibilità di un centro eruttivo, probabilmente di modeste dimensioni, localizzato in prossimità dell’area in esame. particolari campioni di materiale vetroso sono stati rinvenuti nel campione 17b, prelevato al metro 26,5. le indagini in diffrattometria a raggi-x da polveri rivelano l’assoluto stato amorfo di questa sostanza. l’osservazione sem-eds 250 tab. 3 distribuzione della macrofauna del caio. (a= abbondante; f= frequente; c= comune; r= raro; p= presente) macrofauna distribution of caio section. (a= abundant; f= frequent; c= common; r= rare; p= present) r. bizzarri et al. mostra una tipica morfologia da campioni vetrosi (fig. 6d), caratterizzata da frattura concoide/vetrosa. l’analisi chimica semiquantitativa (sem-eds) riporta la seguente composizione media: 28.4% al2o3, 59.4% sio2, 1.6% cao, 0.6% tio2, 8.0% feo, 1.9% mgo. l’ipotesi maturata riguardo la genesi di questi materiali é la fusione di argille (o comunque di litotipi molto ricchi in alluminio) da parte di un fuso magmatico: l’associazione micropaleontologica (tab. 2) rinvenuta nel medesimo campione 17b sembra suffragare tale interpretazione. questo comporterebbe la presenza in loco di un evento effusivo, se pur di modeste dimensioni (es. dicco). il rilevamento geologico dell’area non ha ancora evidenziato la presenza di tale evento e gli studi sono ancora in corso. 66.. ddiissccuussssiioonnee sulla base delle associazioni microfaunistiche, malacologiche e dei caratteri sedimentologici è possibile affermare che la porzione basale del caio (0 23m) comprende sia la parte superiore dell’unità delle “sabbie a flabellipecten” (ambrosetti et al., 1987) che la porzione basale dell’unità “argille e sabbie del chiani tevere” (ambrosetti et al., 1987). l’analisi micropaleontologica ha inoltre permesso di identificare, all’interno delle “argille e sabbie del chiani – tevere”, sedimenti riferibili al pliocene superiore pleistocene inferiore (zona a g. inflata) per la presenza del marker zonale (fig. 5). la successione evolve da un ambiente marino costiero (shoreface superiore) ad un ambiente salmastro durante il pliocene superiore, per poi passare ad un ambiente francamente marino databile al pleistocene inferiore. ad ulteriore conferma dell’età pleistocenica si riscontra la presenza di h. balthica “ospite nordico” (fig. 5). il limite plio – pleistocene è stato posto all’interno delle argille, mentre appare probabile la presenza di una lacuna, riconducibile alla fase erosiva nota in letteratura 251 fig. 5 a) globorotalia inflata (d’orbigny), lato ombelicale, campione 10; b) globorotalia inflata (d’orbigny), lato ombelicale, individuo con margine aperturale rotto, campione12; c) globigerina decoraperta takayanagi & saito, visione laterale, campione 10; d,o,p) bulimina marginata d’orbigny, campioni 10, 11, 16; e,h) planulina ariminensis d’orbigny, lato ombelicale, campione 16; f,g) hyalinea balthica (schroeter) lato ombelicale, campioni 11, 17b; i) uvigerina peregrina cushman, campione 17; l) bulimina costata d’orbigny, campione 11; m) uvigerina mediterranea hofker, campione17b; n) bolivina sp., campione 13; q) anomalinoides sp., campione 2; r) uvigerina pigmea d’orbigny, campione 17b. a) globorotalia inflata (d’orbigny), umbilical view, sample 10; b) globorotalia inflata (d’orbigny), umbilical view, specimen with broken apertural border, sample 12; c) globigerina decoraperta takayanagi & saito, side view, sample 10; d,o,p) bulimina marginata d’orbigny, samples 10, 11, 16; e,h) planulina ariminensis d’orbigny, umbilical view, sample 16; f,g) hyalinea balthica (schroeter) umbilical view, samples 11, 17b; i) uvigerina peregrina cushman, sample 17; l) bulimina costata d’orbigny, sample 11; m) uvigerina mediterranea hofker, sample 17b; n) bolivina sp., sample 13; q) anomalinoides sp., sample 2; r) uvigerina pigmea d’orbigny, sample 17b. l’affioramento del caio ... come “acquatraversa” (ambrosetti & bonadonna, 1967), tra le sabbie argillose e le argille. appare qui opportuna una breve riflessione sul significato di tale termine. ambrosetti et al. (1987) suggeriscono la presenza di una lacuna, estesa dalla parte finale della zona g. crassaformis fin dentro alla zona g. cariacoensis comprendente pertanto l’intera estensione della zona g. inflata. tale hiatus di natura almeno in parte erosiva sarebbe legato principalmente all’attività tettonica distensiva del pliocene medio superiore (ambrosetti et al., 1977), ma sembrerebbe coincidere (azzaroli et al., 1997) con un importante deterioramento climatico che accompagna la caduta del livello marino. la risalita del livello marino nel pleistocene inferiore sembra essere conseguenza di una nuova fase tettonica estensionale, con faglie ad andamento antiappenninico. i dati in nostro possesso sembrano collocare almeno parte dell’affioramento del caio all’interno dell’originaria estensione della suddetta lacuna stratigrafica (ambrosetti et al., 1987). da un lato, si assiste ad una transizione graduale da un ambiente marino costiero ad un salmastro con malacofaune che, malgrado la scomparsa del flabellipecten, non mostrano apprezzabili variazioni e sono le stesse citate in letteratura (piccardi, 1994); una simile tendenza ben si sposa con il trend regressivo del pliocene medio. d’altro canto nelle sovrastanti argille marine, riferibili ad una successiva fase di high – stand, è già presente g. inflata prima della comparsa di forme francamente pleistoceniche (g. oceanica, h. balthica). dal m 23 al m 29 i corpi ghiaiosi, legati ad un contesto deposizionale di conoide alluvionale, testimoniano la fine della tendenza trasgressiva e l’instaurarsi di locali condizioni continentali. le caratteristiche dei depositi ghiaiosi indicano chiaramente l’alternanza di momenti di intenso dilavamento, in cui sono attivi sia processi gravitativi che processi trattivi, canalizzati e non, e momenti di stasi, durante i quali parte dei materiali deposti subisce un’esposizione subaerea, che ne determina ossidazione superficiale. si può ipotizzare un paleoambiente di tipo caldo – umido o temperato – umido, caratterizzato 252 fig. 6 immagini sem (in elettroni retrodiffusi) dei campioni con materiale piroclastico: a) pomice proveniente dal campione 18 (cc: calcite, cpx: clinopirosseno, k-feld: k-feldspato, na-plag: na-plagioclasio); b) pomice proveniente dal campione 18. in questo particolare sono evidenti clinopirosseni idiomorfi tozzi e aciculari nonché minerali zeolitici, dall’aspetto fibroso aciculare, localizzati particolarmente nei vacuoli ; c) pomice proveniente dal campione 17. sono evidenti dei fenocristalli di ortopirosseno enstatitico, di clinopirosseno augitico e di na-plagioclasio, questi ultimi fortemente alterati e associati a minerali zeolitici; d) campione di materiale vetroso rinvenuto nel campione 17b. sem-eds image from samples with volcanoclastic material: a) a pumice from sample 18 (cc: calcite, cpx: clinopyroxene, k-feld: kfeldspar, na-plag: na-plagioclase); b) a pumice from sample 18. are evident hidiomorph acicular and squat clynopyroxenes, fibratus acicular zeolites into the vacuolar porosity; c) a pumice from sample 17; are evident phenocrystals of enstatitic ortopyroxenes, augitic clynopyroxenes and of na-plagioclases (deeply alterated and in assemblage with zeolites); d) glass material from sample 17b. r. bizzarri et al. da una marcata stagionalità, con momenti di intense precipitazioni, motore dei processi di dilavamento e delle “piene” fluviali, seguiti da periodi di “magra” sufficientemente lunghi da permettere l’esposizione subaerea di parte dei depositi. l’età di questi corpi di conoide resta un problema aperto. e’ però possibile proporre alcune considerazioni, mutuate dai dati fin qui acquisiti, che ne suggeriscono un’attribuzione al pleistocene inferiore (emiliano inferiore), sebbene non possa essere del tutto esclusa un’età ancora più recente. 1) tra le microfaune rimaneggiate sono presenti solo forme del pliocene medio – pleistocene inferiore, accompagnate da h. balthica. 2) la petrologia dei clasti, a prescindere dalle litologie legate allo smantellamento del substrato pre-pliocenico, evidenzia la rielaborazione delle litofacies marine sottostanti, principalmente biocalcareniti del pliocene medio – superiore (livello ad amphistegina sensu conti et al., 1983). 3) le piroclastiti, rinvenute dal m 17.5 al m 29, contengono gli stessi pirosseni non alterati, con habitus prismatico pressoché perfetto, i quali non mostrano evidenze di abrasione da trasporto. la costanza dei caratteri per cristalli contenuti all’interno di corpi deposti in ambienti di sedimentazione profondamente diversi suggerisce che i due paleoambienti siano pressoché coevi. 4) sulla base dei dati mineralogici e petrografici preliminari, si possono fare alcune considerazioni generali sull’affinità dei prodotti vulcanici rispetto alle province comagmatiche limitrofe (hks provincia comagmatica romana; ks monti vulsini, roccamonfina, ventotene; provincia magmatica toscana; ulud distretto ultra alcalino umbro-laziale). malgrado le caratteristiche del materiale analizzato non permettano determinazioni radiometriche, la presenza di cristalli di ortopirosseno, mai segnalati nelle altre province magmatiche, suggerisce un’affinità toscana. gli eventi vulcanici legati a tale provincia comagmatica, se si esclude l’attività recente del m. amiata, hanno un’età anteriore rispetto al vulcanismo cimino (1,35 – 0,95 ma) e al complesso del paleo – bolsena (0,576 – 0,505 ma). l’aspetto stesso delle piroclastiti, che mostrano minime evidenze di rielaborazione in ambiente alluvionale, testimonia un trasporto limitato e probabilmente una contemporaneità tra messa in posto del conoide e almeno parte dell’attività eruttiva. 5) nella parte finale dell’affioramento è stata rinvenuta un’associazione a molluschi, costituita da poche forme sia marine che dulcicole, queste ultime riferibili al pleistocene inferiore (esu, com. pers.). le vulcaniti presenti nella sezione del caio potrebbero essere assimilabili a quelle riportate in letteratura da ambrosetti et al. (1968) e bigazzi et al. (1994), come vulcaniti plio-pleistoceniche del lazio e della toscana. sembra che non sia da escludere la possibilità di correlare i livelli vulcanoclastici del caio con uno dei livelli già noti, da oltre 30 anni, e segnalati da uno degli scriventi (p.a.) nella successione di valle ricca (lazio); d’altro canto, appare plausibile la correlabilità con un centro di emissione ad affinità tirrenica non noto, ma supposto anche da altri autori (bigazzi et al., 1994). la presenza di materiale vetroso, probabilmente dovuto alla fusione di minerali argillosi e rinvenuto nel campione 17b, non esclude che la frazione piroclastica presente possa provenire da un piccolo centro vulcanico situato nelle vicinanze e non ancora evidenziato dal rilevamento geologico. diversi sono stati gli eventi vulcanici di modeste dimensioni (es. dicchi) segnalati in umbria e lazio nel corso degli ultimi anni (stoppa & cundari, 1995; 1998; stoppa et al., 1997), ma si tratta in tutti i casi di eventi più recenti. un evento continentale, analogo a quello da noi riscontrato, intercalato alle “argille e sabbie del chiani –tevere”, è stato descritto da girotti & piccardi (1994) immediatamente a sud dell’area in esame (camartana). tale evento viene riferito dagli autori al santerniano (fase erosiva “aulla”), più in base ai dati conosciuti riguardo all’età delle “argille e sabbie del chiani –tevere” che non per la presenza di riferimenti temporali certi. con i dati attualmente in nostro possesso, è solo possibile ipotizzare un’analogo contesto deposizionale. l’argomento merita un successivo approfondimento, per determinare se si tratti dello stesso evento oppure di due eventi distinti, di ordine minore, all’interno di un evento di ordine maggiore. in conclusione, alcune significative novità sembrano emergere dai dati fin qui raccolti: 1) il rinvenimento di h. balthica all’interno di depositi riferibili alle “argille e sabbie del chiani –tevere”, evento finora mai riscontrato, se da un lato sembra permettere l’estensione temporale di tale unità fin dentro l’emiliano, dall’altro mette in discussione la proposta attribuzione al santerniano della definitiva regressione marina di questa porzione di costa paleotirrenica (ambrosetti et al., 1987). 2) il ritrovamento di piroclastiti a probabile affinità toscana suggerisce l’esistenza di un evento vulcanico non noto, riferibile al pleistocene inferiore, di età antecedente sia all’attività cimina più antica, che a quella del “paleo bolsena”. 3) la presenza di depositi francamente continentali, di età confrontabile con quella delle sottostanti argille marine, se da un lato complica la ricostruzione del quadro paleogeografico dell’area, dall’altro evidenzia l’esistenza di più eventi di fluttuazione del l.m. durante il pleistocene inferiore (santerniano – emiliano). la parte superiore dell’affioramento del caio, pur evidenziando una situazione paleoambientale locale, testimonia quindi l’estrema variabilità laterale dei depositi del pleistocene inferiore, riferibili o eteropici alle “argille e sabbie del chiani – tevere”. infatti, è ipotizzabile un’articolazione delle morfologie costiere, in parte ereditate ma senz’altro esasperate dall’intensa tettonica che caratterizza il passaggio pliocene – pleistocene: questa fase, con assi strutturali ad andamento antiappenninico, disloca i depositi del pliocene, che vengono in parte rielaborati, e determina una marcata eteropia di facies. in questo contesto, in cui le stesse argille documentano ambienti marini di profondità diverse, complessivamente più distali andando da est ad ovest, si impostavano corpi di conoide, come quello del caio, che drenavano verso sw o nw, rimaneggiando le differenti facies presenti nel bacino in cui confluivano. nell’affioramento descritto mancano del tutto depositi di barra di foce e di piana costiera, mentre sono presenti corpi di ambiente francamente continentale, collegabili alla porzione medio – prossimale del conoide, direttamente a contatto con depositi marini, che potrebbero forse costituire la porzione più distale del prodelta. una simile situazione di affioramento, in cui non tutti i depositi sono contemporaneamente conservati, è stata descritta ad esempio nel fan – delta di loro – ciuffenna, in valdarno (billi et al., 1991). 253l’affioramento del caio ... non è da escludere che nell’area esistano situazioni analoghe a quella del caio, che potranno essere evidenziate da un dettagliato rilevamento. rriinnggrraazziiaammeennttii gli autori intendono qui ringraziare la prof. daniela esu ed il prof. francesco paolo bonadonna per la loro collaborazione, nonché il dott. luca costantini, che ci ha segnalato l’affioramento. vogliamo inoltre ringraziare il prof. roberto colacicchi ed il prof. leonsevero passeri per la loro disponibilità ad interessanti e costruttive discussioni. llaavvoorrii cciittaattii aa.vv. 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(1997) new mineral data from the kamafugite carbonatite association: the melilitolite from san venanzo, italy mineral petrol., 7788, 251-265. 255 ms. ricevuto il 30 aprile 2003 testo definitivo ricevuto il 7 ottobre 2003 ms. received: april 30, 2003 final text received: october 7, 2003 l’affioramento del caio ... amq_28(1) coloph 3.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 28 (1), 2015, xi xiii report on the inqua 6th international workshop “active tectonics, paleoseismology and archaeoseismology” fucino 2015. april 19-24, 2015, pescina (aq) stefano gori, emanuela falcucci, fabrizio galadini istituto nazionale di geofisica e vulcanologia, l’aquila, italy corresponding author: s. gori <stefano.gori@ingv.it > abstract: the inqua 6th international workshop on active tectonics, paleoseismology and archaeoseismology, held in pescina (l’aquila, italy) on april 19-24, 2015, pointed out the recent scientific outcomes derived from both classical and new methodological approaches and techniques, and included a two-day field trip in the epicentral areas of the 1915 fucino earthquake and of the april 6, 2009, l’aquila earthquake. keywords: paleoseismology, active tectonics, inqua workshop, fucino 2015, italy one hundred years after the great marsica earthquake (estimated magnitude 7), that hardly struck central italy on the 13th of january, 1915, the international union for quaternary science (inqua) sponsored the 6th international workshop on active tectonics, paleoseismology and archaeoseismology. the workshop was organised by istituto nazionale di geofisica e vulcanologia (ingv), istituto superiore per la protezione e la ricerca ambientale (ispra) and università dell’insubria, to foster discussion, and to share the most recent achievements, between different disciplines in the field of the earthquake geology. such an important scientific appointment was held between april 19 and 24, 2015, in the town of pescina, which is located in the epicentral area of the 1915 earthquake. the town was the ideal stage to commemorate the tragic event, as the earthquake traces can still be distinguished on the remnants of the walls of the old town centre that, together with many villages and towns around the fucino plain area, stand as open air memorials in honour of the more than 30000 fatalities. the workshop gathered together more than two hundreds researchers from all continents, who daily spend their efforts in the earthquake science, with the aim of obtaining up-to-date information to be incorporated in seismic hazard analyses and to be used for mitigating seismic risk. the participants attended to a three-day scientific discussion on quaternary geology, paleoseismology, earthquake engineering, seismic hazard, tsunami hazfig. 1 northern wall of the trench dug across the 1915 earthquake surface rupture. main fault plane, red arrow ard and archaeoseismology, followed by a two-day fieldtrip in the epicentral areas of the 1915 earthquake and of the 6th of april, 2009 l’aquila earthquake (moment magnitude 6.1). the most recent scientific outcomes derived from different methods and techniques – i.e., from the classical geological field investigations to the cosmogenic nuclides dating of exposed fault planes – were illustrated by a large number of oral and poster presentations. the first day of field trip was spent along the fucino plain area, specifically along the trace of the active normal fault that ruptured during the 1915 earthquake, known and the fucino fault. firstly, a paleoseismological trench dug ad hoc for the meeting purpose across the surface rupture reported by oddone – the seismologist that surveyed the fucino area in the aftermath of the event – was visited (fig. 1). in general, paleoseismological trenching aims at unveiling the kinematic history of a given active tectonic structure, by defining how often it moves, the elapsed time since the last activation, and how strong can be an earthquake determined by the fault activation. at this purpose, one or more excavations are made across the surface expression of an active fault in order to uncover recent sediments that might have undergone deformation induced by the fault motions. the trench visited during the workshop, and illustrated by paolo galli (dpcn), aimed at showing the participants the geological traces of the surface faulting occurred during the 1915 seismic event, and of previous episodes of fault activation. in particular, the analysis of the trench walls allowed the identification of the faulting event occurred during the late antiquity, in 508 (or 484) ad; this event resulted in a large magnitude earthquake – comparable to the 1915 one – that determined heavy damages to the ancient settlements surrounding the fucino area, being also likely responsible for significant damages to colosseum in rome. secondly, a quarry (known as cava santilli) located close to venere dei marsi was visited during the fieldtrip; it exposed one of the planes of the fucino fault that brought the carbonate bedrock (footwall) into contact with late holocene slope-derived deposits (hanging wall) (fig. 2). the scarplet related to the northernmost segment of the fucino fault, affecting the south-western slopes of the magnola mts., was also shown and the evidence of both the long-term and recent activity of the structure, represented by the displacement of slope deposits spanning the whole quaternary, was illustrated. paolo messina (cnr-igag) described the quaternary stratigraphic sequence hosted by the fucino basin, in particular the succession exposed near pescina. finally, the remnants of the 1915 earthquake coseismic scarp were also visited and described by alessandro m. michetti (università dell’insubria); furthermore, gerald roberts (birkbeck university of london, uk) described the holocene exposition history of the mt. serrone fault scarp, related to one of the segments of the fucino fault. the second day of the field trip was devoted to the l’aquila-san demetrio ne’ vestini basin area, the epicentral zone of the 2009 earthquake. during the first part of the fieldtrip, the scarp related to the san demetrio active normal fault was shown by anna maria blumetti (ispra) and the results of paleoseismological analyses made along the fault were discussed. then, the early quaternary continental stratigraphic sequence hosted by the l’aquila-san demetrio ne’ vestini depression was depicted by stefano pucci (ingv), fabio villani (ingv) and colleagues (fig. 3), particularly the paleo-deltaic succession exposed by a quarry in the area of poggio xii ciaranfi n. fig. 2 wall of the “cava santilli” quarry showing the fucino fault plane (yellow arrows) that places in contact holocene slope deposits, in the hanging wall (on the left), with the carbonate bedrock, in the footwall (on the right). picenze. then, a normal fault active during the early stages of formation of the depression was shown along the fosso dell’inferno fluvial incision. at the end of the field trip the city of l’aquila was visited. laura graziani (ingv) and filippo bernardini (ingv) illustrated the seismic history and provided the macroseismic description of the city. sara amoroso (ingv), francesco potenza (università dell’aquila) and giacomo tironi (freelance engineer) showed the participants the damages induced by the 2009 seismic event and described the current restoration activities. xiii lower-middle pleistocene in italy fig. 3 s. pucci and his ingv colleagues illustrate the stratigraphic framework of the l’aquila-san demetrio ne’ vestini basin. ms. received: may 12, 2015 final text received: april 18, 2015 amq 23 giraudi available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 26 (2), 2013, 110 122 a late-pleistocene phase of saharan dust deposition in the high apennine mountains (italy) . carlo giraudi 1, giovanni zanchetta 2, roberto sulpizio 3 1 enea c.r. saluggia, vercelli, italy 2 dipartimento di scienze della terra, university of pisa, italy 3 cirisivu, c/o dipartimento geomineralogico, university of bari, italy corresponding author: c. giraudi <carlo.giraudi@enea.it> abstract: the presence of late pleistocene hexogen quartz-rich loess on apennine massifs, formed by limestone rocks, has been reported since the 90s of the 20th century, and indicates that the dust must come from outside areas. the thickness of the aeolian deposits decrease from south to north, becoming null north of the latitude of 42° n; thus indicating that the dust come from south. the study of new exposures on mount matese, where the loess is interbedded with tephra layers and in proglacial lake sediments, have led to a more detailed chronology of the phases of sedimentation. specifically, we have established that the loess deposition was contemporaneous with the late pleistocene phases of intense saharan dust sedimentation in maar lakes in italy, and in the mediterranean sea. the geochemical characterization and the recognition of three tephra layers have enabled us to establish that the end of the loess sedimentation occurred at the transition between the oldest dryas stadial (or greenland stadial gs-2) and the bölling/alleröd interstadial (or greenland interstadial gl-1), simultaneously with the start of the african humid period. we hypothesize, therefore, that the quartz-rich loess in the apennines was formed by the sedimentation of saharan dust. the greater amount of dust, brought by southerly winds, would have been sedimented during periods of increased aridity in north africa which were coeval with the apennines last glacial maximum and stadial phases. keywords: late pleistocene, saharan loess, tephra layers, apennine chain, peninsular italy. 1. introduction the sahara produces more aeolian dust than any other world desert, and saharan dust has an important impact on soil formation and sediment cycles (goudie & middleton, 2001). its influence spreads far beyond africa, due to the great distances over which saharan dust is transported. deposition of dust to land surfaces may produce terra rossa soils in southern europe and the levant (yaalon & ganor, 1973; macleod, 1980; rapp, 1984) and loess (rapp & nihlén, 1991; stuut et al. 2009). the present saharan dust sedimentation in italy is well known and has been studied at least since the ’50 (fett, 1958). southern air masses bring dust of saharan origin to the northern shore of the mediterranean sea and, sometimes, to far northern latitudes (franzén et al., 1994). saharan dust sedimentation on the apennines is easily documented at higher altitudes, where, at the end of winter, the snow contains several thin dust horizons light brown-pink in colour. on the high mountains of the central and southern apennines is present a late glacial loess, of the same color of the saharan dust, , mainly consisting of quartz (frezzotti & giraudi, 1990a; 1990b; giraudi 1997,1998a, 2001, 2004; zanchetta et al., 2012). since the massifs on which the loess is present are of limestone rocks, dust quartz-rich must come from outside areas, and the sahara was considered the possible source region (giraudi,2011). the occurrence of saharan dust in the late pleistocene and holocene sediments of the italian peninsula has been proposed by narcisi (2000) which documented the presence of varying percentages of aeolian quartz in the sediments cored in the volcanic maar lakes formed by sio2 under-saturated ultra-potassic rocks. the sedimentation rate of quartz has undergone significant changes over time, but the sedimentation has never ceased altogether. andreucci et al. (2012) also provided evidence for saharan dust sedimentation during the late pleistocene in the island of sardinia. the presence of late pleistocene and holocene sediments partially formed by saharan dust, confirms that, also in the past, southern air masses have reached the italian peninsula. in the present paper new data on the high apennines loess are reported and some stratigraphic successions are discussed in order to provide a reliable chronological framework and establishing the climatic factors leading the variation of the dust transport and deposition in central-southern italy (e.g. humidity variation versus southern circulation weakness). in some sections studied on the matese massif (fig. 1), the quartz -rich loess is interbedded with tephra layers from eruptions of the nearby phlegrean fields. the geochemical characterization of three tephra layers, in addition to improve the dating of the sedimentation of the loess, allows us to correlate and synchronize the studied succession with stratigraphic records containing the same tephras. the dating of the loess also allows a close chronological correlation with some documented phases of increase and decrease in saharan dust sedimentation in the mediterranean sea and the atlantic ocean. 2. methods the lithostratigraphic data reported in the present paper were collected by studying exposed sedimentary successions and short cores retrieved through a hand augers. the studied sites are located above 1400 m a.s.l. in areas glaciated during the local last glacial maximum (lgm) and following stadial phases in some central-southern apennine massifs, consisting of mesocenozoic limestone. the carbonate composition of the catchment excludes a local source of the aeolian quartz. attention has been paid more on the aeolian deposits that cover moraines, formed during lgm or in subsequent stadial phases, or that lie in small retromorainic closed depressions formed by the melting of dead ice. the choice of these conditions warrant, even in the absence of absolute dating, a reliable correlation with the late pleistocene phases of expansion and retreat of the glaciers, which had a primary role in the shaping of the higher apennine massifs. in addition, the sediments on the summit of moraine ridges may have been formed only by aeolian deposits and tephra layers, while the lacustrine sediments lying inside closed depressions, having an endorheic drainage, can only come from the very small catchments with the contribute of aeolian sediments and tephra layers. although the aim of the present study is the dating of the loess deposition, we also report some grain size analyses (performed by frezzotti & giraudi, 1990a; 1990b) of the loess from the matese site a (in fig. 1), and sites on the m. greco massif, where the aeolian sediment are better preserved (fig. 1; 2) in the other sections, the aeolian origin of the sediments identified as loess is confirmed by the microscopic observation of the quartz grains, which are giraudi c. et al 111 fig. 1 – reference map and outline (inset) of the main glacial features and deposits on the matese massif . the location of the stratigraphic sections studied is also shown. 112 late-pleistocene phase of saharan dust deposition in the high apennine mountains (italy) frosted. moreover, when sediments are not affected by pedogenesis, field recognition of the loess is quite simple thanks to its colour (in general 7.5yr 4/6, munsell soil colour chart) which contrast with background of the non-aeolian deposits. in order to verify the presence of quartz of aeolian origin, the mineralogical composition of proglacial lacustrine sediments has been considered. the chronology of the phases of aeolian sedimentation is based on the correlation between glacial and aeolian deposits, on radiocarbon datings of organic matter in the sediments, and on the recognition of tephra layers by geochemical methods. samples collected in the field for geochemical analyses were air dried, then washed in diluted h2o2, filtered and dried in an oven at 40 °c for ca 24 h. the samples were quite rich in glass shards, so no enrichment procedure was performed. the samples were then embedded in epoxy resin and screened for glass shards and micro-pumice fragments using scanning electron microscopy (sem). energy-dispersive-spectrometry (eds) analyses of glass shards and micro-pumice fragments were performed using an edax-dx microanalyzer mounted on a philips sem 515 at the dipartimento di scienze della terra, university of pisa, employing a 20 kv acceleration voltage, 100 s live time counting, 2100-2400 shots per second, and zaf correction. the zaf correction procedure does not include natural or synthetic standards for reference, and requires the results to be normalized at a given value (which was chosen as 100%). eds data were calibrated using a combination of well characterized natural minerals (see marianelli & sbrana, 1998; zanchetta et al., 2012). to avoid alkali loss, especially na, a window spot usually ca 10 μm wide was used. owing to the different shape and size of the glass shards, a smaller size was sometimes used and this could influence analytical data (hunt and hill, 2001). several trials for comparing the performance of the pisa sem-eds with wave dispersion spectroscopy (wds) have been extensively discussed by cioni et al. (1997), marianelli & sbrana (1998), vogel et al. (2010), sulpizio et al. (2010) and caron et al. (2010, 2012). 3. results 3.1. occurrence of quartz-rich loess 3.1.1. periglacial deposits of the central and southern apennine massifs the presence of a loess formed mainly by quartz (up to 70-80%) in the highest central and southern apennine massifs has been reported by frezzotti & giraudi (1990a; 1990b), giraudi (1997,1998a, 2001, 2004), zanchetta et al. (2012). the loess, studied in different exposures and characterized from the mineralogical and granulometric point of view by frezzotti & giraudi (1990a; 1990b), always lies at the top of glacial and fluvioglacial sediments matching the post-lgm phases of glacial retreat. the loess sedimentation occurred before the formation of a peat layer dated 16,514-14,280 cal a bp. however, in glacial and periglacial environments subject to erosion and cryoturbation processes, the preservation of late glacial aeolian deposits may have been discontinuous. the peat horizon may have been deposited on erosion surfaces. therefore, the dating of the end of the aeolian sedimentation assumed in the literature remains uncertain. the loess also represent the oldest sediments that fill the dead-ice depressions between the lgm moraines fig. 2 the a-f stratigraphic sections studied on the matese massif showing the presence of sediments of glacial, aeolian, colluvial origin, tephra layers and soils (site location in fig.1). fig. 3 – grain size curves of the quartz-rich loess sampled in stratigraphic section a (site location in fig.1), on the matese massif, and in the aremogna and polverino plains, on the greco massif. modified from frezzotti & giraudi (1990a; b). (giraudi, 2001; zanchetta et al., 2012). the new exposures studied on m. matese (fig. 2) confirm that the loess formed mainly of quartz lies on lgm and some stadial moraines. the stratigraphic sections show quite different sedimentary sequences. the section a (frezzotti & giraudi, 1990a) shows a c. 20 cm-thick layer of aeolian silt, coloured 7.5yr 4/6; the grain size of the bulk sediment (fig. 3) is those typical of a loess. the loess is made mainly by quartz (about 70%), calcite and phyllosilicates. excluding quartz, part of the other minerals could have a local origin. in the section a, the loess is covered by the matese 1 tephra. this tephra, according to frezzotti & narcisi (1996) was deposited during the eruption of the phlegrean fields known as neapolitan yellow tuff. the tephra is covered by volcanic mineral-rich aeolian sediments. the loess is easily recognizable because of its colour which is very different from that of the sediments formed by carbonate clasts, i.e. whitish and light brown, and from that of tephra layers and aeolian deposits consisting of reworked volcanic minerals showing different grain-size and mineralogical components and a variety of colours. in addition, in the other sections, the aeolian origin of the sediments identified as loess is confirmed by the microscopic observation of the quartz grains, which are frosted. the section b (fig. 1; 2) is formed by blocks of carbonate rocks in sandy silt matrix, which form one of the stadial moraines of m. gallinola, covered by thinner sediments. the post-glacial sediments have been sampled through a hand auger and are formed by: aeolian silt, coloured 7.5yr 4/6 of the munsell soil colour chart, 20-25 cm thick; the silt corresponds to the loess of the section a sampled a few hundred metres away; tephra layers, about 10 cm thick, consisting of greenish sandy silt (matese 5); aeolian silt (loess), coloured 7.5yr 4/6 of the munsell soil colour chart, 5-15 cm thick; tephra sandy-silty, light green at the base and then grey-yellow, 30 cm thick (matese 1); volcanic mineral-rich aeolian sediments. the section c, like the section b, is formed by blocks of carbonate rocks in sandy silt matrix, which form the moraines. the glacial debris is covered by thinner sediments, sampled through a hand auger, formed by: aeolian silt, coloured 7.5yr 4/6 of the munsell soil colour chart, about 10 cm thick; the silt corresponds to the loess of the section a sampled a few hundred metres away; 80 cm of colluvium; 25 cm of colluvial soil; tephra sandy-silty, greenish in colour, 10 cm thick (matese 5). volcanic mineral-rich colluvial soil; quartz-rich aeolian silt, coloured 7.5yr 4/6 of the munsell soil colour chart, about 10 cm thick; tephra sandy-silty, light green at the base and then grey-yellow, 25 cm thick (matese 1); volcanic mineral-rich aeolian sediments. the section d, close to the c section, is an exposure of sandy-silty sediments overlying blocks in sandy silt matrix forming the campo puzzo lateral moraines. the sediments are formed by: aeolian silt the silt, 10-15 cm thick, corresponding to the loess of the section a, sampled a few hundred metres away, containing interbedded colluvial horizons, coloured 7.5yr 4/6 of the munsell soil colour chart; tephra layers, about 5-10 cm thick, consisting of greenish sandy silt (matese 5); aeolian silt (loess), coloured 7.5yr 4/6 of the munsell soil colour chart, 5-15 cm thick, containing a thin colluvial horizons formed by phyllosilicates and reworked volcanic minerals; tephra sandy-silty, light green at the base and then grey-yellow, 30 cm thick (matese 1); volcanic mineral-rich aeolian sediments with a convoluted lamination. the section e is an exposure close to the d section. the sediments deposited at the top of the stadial moraine are formed by: a few centimeters thick aeolian silt, coloured 7.5yr 4/6 of the munsell soil colour chart; the silt corresponds to the loess of the section a; tephra sandy-silty, grey in colour (matese 2) about 57 cm thick; tephra sandy-silty, light green at the base and then grey-yellow, 25-30 cm thick (matese 1); volcanic mineral-rich aeolian sediments. the section f, an exposure about 1 km ne of the sections a and b, is formed by: blocks of carbonate rocks in sandy silt matrix, which form one of the stadial moraines of m. gallinola; aeolian silt, coloured 7.5yr 4/6 of the munsell soil colour chart, 10-15 cm thick; the silt corresponds to the loess of the section a; colluvial silt, 10-15 cm thick; tephra sandy-silty, light green at the base and then grey-yellow, 30-50 cm thick (matese 1); colluvial sediments and colluvial soils containing a tephra layer. the tephra, identified by zanchetta et al. (2012), was produced by the agnano monte spina eruption of the phlegrean fields, dated to the midholocene. the difference between the sediments of the studied sections shows that we are dealing with very discontinuous sedimentary successions, as one would expect at high altitudes in a former periglacial environment. in spite of this, the phases of the loess and tephra deposition are generally well recognisable and the difference between quartz-rich and volcanic mineral-rich aeolian sediments is very easy to detect in the field because the colour, the grain size and the mineralogical composition. the composite stratigraphy of the post-glacial sediments in the studied area is as follows (from bottom to top): blocks of carbonate rocks in sandy silt matrix, which form one of the stadial moraines of m. gallinola; aeolian silt, coloured 7.5yr 4/6 of the munsell soil colour chart; in section d the silts contain interbedded colluvial horizons; tephra layers, about 10 cm thick, consisting of green 113 giraudi c. et al ish sandy silt (matese 5); aeolian silt (loess), coloured 7.5yr 4/6 of the munsell soil colour chart; in section d thin colluvial horizons are intebedded with aeolian silts; tephra sandy-silty, grey in colour (matese 2); tephra sandy-silty, light green at the base and then grey-yellow (matese 1). the deposition of the loess began before the fall of tephra layer matese 5 and ended before the fall of tephra matese 2 and matese 1. the sediments deposited after the fall of the matese 1 tephra are not discussed in detail, but it should be noted that the aeolian sand and silt, consisting of reworked volcanic minerals younger than matese 1 (section d, fig. 2), show a convoluted lamination. these sediments were deformed by cryoturbation processes, already observed on m. matese by palmentola & acquafredda (1983). it follows that the cryoturbation must have occurred in a period of intense cold that followed the fall of matese 1 tephra, corresponding, according to giraudi (1997), to the younger dryas. in section f, the matese 1 tephra is followed by colluvia and colluvial soils containing the tephra layer matese 4 dated to the mid-holocene. 3.1.2. lake sediments on other mountains of the central apennines in order to check whether the sedimentation of quartz-rich dust occurred also during the local lgm, some analyses have been carried out on the mineralogical composition of lake sediments of pro-glacial environment. microscopic observations and mineralogical analyses carried out on some samples by means of x-ray diffractometry (anselmi b., unpublished data) evidenced high percentages of quartz (around 20%) in some sediments, found on the gran sasso massif (42°24’n, 13° 38’e) (fig. 1), dated at about 27-26 cal ka bp by giraudi & frezzotti (1997). also the analyses of the sediments from another pro-glacial lake formed during the local lgm of the most extensive glacier of monte terminillo (42°30’n, 12°58’e), with a catchment basin of limestone, reported by giraudi (1998c), revealed a content of quartz slightly more than 20%. this implies that the aeolian sedimentation on the apennine mountains began before than previously assumed. in addition, the dust sedimented at least up to the latitude of m. terminillo, but the amount was not sufficient to produce distinctive layer to be observed in exposures. finally, it is clear that the sedimentation of aeolian quartz was contemporary to the apennine glacial expansions and retreats. 3.2. tephrostratigraphy of the matese samples the chemical composition of the tephra layers matese 1, matese 2 and matese 5 was determined in order to establish the possible provenance and the correlation with known eruptions and thus to obtain a more precise chronology of the studied successions. the tephra layers considered are interbedded with or lying on top of the loess, and so the correct identification of the tephra layers can enable us to have a chronological constraint for the end of the aeolian sedimentation and for correlating it with other environmental events documented by proxy-data of sedimentary records containing the same tephras (e.g. lowe, 2011; lowe et al., 2007; zanchetta et al., 2011). matese 1 (lab. code pi107). it was sampled in the section e (fig. 1, 2). chemical composition (table 1) matches quite well with the compositional variability observed in the neapolitan yellow tuff (tomilinson et al., 2012), which has been found in distal setting and make this layer quite characteristic for its identification (fig. 4; narcisi, 1999; siani et al., 2004; wulf et al., 2004; lane et al., 2011), including the studied area (e.g. frezzotti & narcisi, 1996). chronology of the nyt is not completely defined. bayesian integration of dating and stratigraphic information suggest an age for nyt of 14,320-13,900 cal a bp (blockley et al., 2008). whereas 39ar/40ar dating indicate an age of 14.9±0.4 ka (deino et al., 2004). lake monticchio record based on varve counting and extrapolation of sedimentation rate in intervals not varved shows an age of 14,120±710 varve yr bp. these ages are in agreement with the dating of a peat layer below nyt reported by frezzotti & giraudi, (1990a). overall, these ages partially overlap in the 2σ range. stratigraphically, however, this may be considered within the greenland interstadial i (gi-1) in the greenland event stratigraphy (siani et al., 2004), as also shown by the pollen data from lägsee (austria, schmidt et al., 2002) and monticchio (wulf et al., 2004). matese 2 and matese 5 (lab. code pi108). the matese 2 sample was taken in section e, while the matese 5 sample came from section d (fig. 1, 2). these levels, on the basis of their stratigraphic position (just below nyt) and homogenous trachytes composition, can be correlated with the so-called tufi biancastri (pappalardo et al., 1999; tomlinson et al., 2012). tufi biancastri have been dated by the 40ar/39ar method yielding ages between 14.6 ±0.6 and 17.9±0.5 ka. at monticchio an ash layer correlated with tufi biancastri is dated at 14,560±710 varve yr bp (wulf et al., 2008). these levels also correspond to ln1 and ln2 in the marine core md90917 (siani et al., 2004). in this core the ln1 and ln2 tephras have an age of between ca 13.8 ka to 15.2 ka cal bp. oxygen isotope curves suggest that ln1 and ln2 tephra deposition occurred between the onset of gi-1 and the end of the greenland stadial gs-2 (siani et al., 2004). recently these tephra layers seem to be present also at lake prespa (aufgebauer et al., 2012), as in core md90917 they are probably close to the base of bölling /alleröd and one at the transition between the oldest dryas and bölling/ alleröd. however, these deposits are currently poorly known in terms of age, chemistry and dispersion. 3.2. other occurrences of quartz-rich loess in central and southern apennine massifs the apennines quartz-rich loess has been identified also in exposed or cored sedimentary succession taken in small depressions associated with late pleisto 114 late-pleistocene phase of saharan dust deposition in the high apennine mountains (italy) cene glacial landforms, from pollino to velino massifs (frezzotti & giraudi 1990a; 1990b; giraudi, 1997;1998a; 2001; 2004; zanchetta et al.,2012). two grain-size analises of the loess (fig. 3) have been reported by frezzotti & giraudi (1990a; 1990b). in the central apennines the sedimentary series containing the loess are, generally, formed by: lgm or stadial till or glaciofluvial deposits formed by gravel in a whitish calcareous sandy-silty matrix, at the bottom; at the top of the glaciofluvial deposits the matrix is darker and enriched by quartz. quartz-rich loess, formed by silt, coloured 7.5yr 4/6 (munsell soil colour chart), from a few to 40 cm-thick deposits. where the thickness of the loess is greater, the sediments at the top are depleted in carbonates which increase toward the bottom. the mineralogical analysis of the sediments has evidenced that quartz is prevalent and that calcite, muscovite and kaolinite are present. therefore, the minerals are mostly allothigenous. in some places, near the top of the loess there is a very thin tephra layer, formed by glass, kfeldspar, plagioclase, pyroxene and amphibole. 115 tab. 1 major oxides for the studied tephra. giraudi c. et al 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 mean st dev sio2 58.76 61.47 60.7 60.71 60.98 60.66 57.34 57.06 57.82 60.58 60.5 59.6 60.9 58.09 57.31 59.50 1.59 tio2 0.6 0.23 0.52 0.4 0.41 0.41 0.56 0.59 0.69 0.5 0.39 0.47 0.46 0.34 0.59 0.48 0.12 al2o3 19.3 18.72 19.06 19.77 19.07 19.11 19.29 19.02 19.29 18.88 19.3 19.04 19.01 19.48 19.37 19.18 0.26 feotot 3.85 2.91 3.07 3.43 2.9 3.02 4.87 5.25 4.62 3.16 2.69 3.68 2.85 4.29 4.77 3.69 0.86 mno 0.23 0 0.13 0 0.25 0.08 0.13 0.1 0.17 0.08 0.24 0.22 0.24 0 0.16 0.14 0.09 mgo 0.96 0.72 0.7 0.76 0.5 0.61 1.32 1.76 1.2 0.76 0.82 0.91 0.48 1.35 1.52 0.96 0.39 cao 2.99 2.33 2.47 2.45 2.21 2.42 4.12 4.79 3.68 2.43 2.15 2.94 2.19 3.85 4.18 3.01 0.88 na2o 4.29 4.27 4.36 4.23 4.62 4.53 3.51 3.37 3.75 4.05 4.2 4.28 4.7 3.89 3.88 4.13 0.39 k2o 8.48 8.76 8.49 7.67 8.57 8.58 8.35 7.57 8.3 9.07 9.19 8.31 8.61 8.22 7.8 8.40 0.46 p2o5 0 0 0 0 0 0 0 0.04 0 0 0 0 0 0 0 0.00 0.01 clo 0.54 0.59 0.51 0.59 0.51 0.58 0.51 0.44 0.48 0.48 0.53 0.56 0.55 0.5 0.43 0.52 0.05 total 100.00 100.00 100.01 100.01 100.02 100 100 99.99 100 99.99 100.01 100.01 99.99 100.01 100.01 total alkali 12.77 13.03 12.85 11.9 13.19 13.11 11.86 10.94 12.05 13.12 13.39 12.59 13.31 12.11 11.68 alkali ratio 1.98 2.05 1.95 1.81 1.85 1.89 2.38 2.25 2.21 2.24 2.19 1.94 1.83 2.11 2.01 1 2 3 4 5 6 7 8 9 10 11 12 mean st dev sio2 61.08 60.93 60.79 60.75 61.23 60.88 60.78 61.11 61.08 61.22 60.78 60.92 60.96 0.18 tio2 0.22 0.28 0.44 0.44 0.22 0.43 0.42 0.36 0.42 0.52 0.45 0.35 0.38 0.10 al2o3 19.15 19.21 19.21 18.9 19.18 18.93 19.07 19.13 18.89 19.12 19.11 19.14 19.09 0.12 feotot 2.82 2.87 2.95 2.89 2.81 2.95 2.92 2.87 3.02 2.84 3.01 2.79 2.90 0.08 mno 0 0.08 0.25 0.24 0 0.2 0.09 0 0.08 0.24 0.16 0.13 0.12 0.10 mgo 0.53 0.63 0.44 0.54 0.36 0.35 0.57 0.46 0.55 0.49 0.56 0.64 0.51 0.09 cao 2.24 2.31 2.16 2.26 2.21 2.31 2.15 2.14 2.09 2.12 2.23 2.23 2.20 0.07 na2o 4.79 4.58 4.37 4.43 4.48 4.46 4.62 4.52 4.43 4.51 4.42 4.29 4.49 0.13 k2o 8.59 8.6 8.82 8.99 8.99 8.96 8.78 8.92 8.86 8.44 8.77 9.01 8.81 0.18 p2o5 0 0 0 0 0 0 0 0 0 0 0 0 0.00 0.00 clo 0.6 0.52 0.58 0.56 0.52 0.54 0.58 0.5 0.59 0.52 0.51 0.5 0.54 0.04 total 100.02 100.01 100.01 100.00 100.00 100.01 99.98 100.01 100.01 100.02 100.00 100.00 total alkali 13.38 13.18 13.19 13.42 13.47 13.42 13.4 13.44 13.29 12.95 13.19 13.3 alkali ratio 1.79 1.88 2.02 2.03 2.01 2.01 1.90 1.97 2.00 1.87 1.98 2.10 1 2 3 4 5 6 7 8 9 10 mean st dev sio2 63.33 63.67 62.5 63.42 63.85 63.26 63.58 63.41 63.14 63.51 63.37 0.37 tio2 0.38 0.27 0.5 0.4 0.22 0.37 0.27 0.22 0.43 0.38 0.34 0.09 al2o3 18.47 18.35 18.77 18.33 18.36 18.19 18.46 18.63 18.91 18.48 18.50 0.22 feotot 2.29 2.42 2.53 2.42 2.26 2.37 2.21 2.39 2.75 2.15 2.38 0.17 mno 0.12 0.19 0.16 0.18 0 0.15 0.13 0.09 0.21 0.06 0.13 0.06 mgo 0.24 0.3 0.33 0.25 0.27 0.41 0.37 0.28 0.24 0.26 0.30 0.06 cao 1.45 1.4 1.65 1.47 1.53 1.53 1.52 1.57 1.4 1.53 1.51 0.08 na2o 6.14 5.8 5.47 5.88 5.77 6.13 6.08 5.62 5.86 5.94 5.87 0.22 k2o 6.97 6.91 7.52 6.94 7.17 7.03 6.77 7.21 6.4 7.15 7.01 0.30 p2o5 0 0 0 0 0 0 0 0 0 0 0.00 0.00 clo 0.61 0.7 0.57 0.72 0.59 0.57 0.59 0.59 0.66 0.54 0.61 0.06 total 100.00 100.01 100.00 100.01 100.02 100.01 99.98 100.01 100.00 100.00 total alkali 13.11 12.71 12.99 12.82 12.94 13.16 12.85 12.83 12.26 13.09 alkali ratio 1.14 1.19 1.37 1.18 1.24 1.15 1.11 1.28 1.09 1.20 matese 1 matese 2 matese 5 colluvium made of quartz-rich silt derived from the loess, from a few to 30-40 cm thick. in some cases, interbedded with the colluvium, there is a thin tephra layer, having the same mineralogical composition of the horizon near the top of the loess. tephra layer from a few to 20 cm thick, studied in a number of sedimentary sequences, correlated to the neapolitan yellow tuff (nyt) volcanic eruption from the phlegraean fields (frezzotti & narcisi, 1996). silt of lacustrine or aeolian origin derived from the reworking of the nyt. alternating soils, lacustrine or colluvial deposits, and tephra layers dated at the holocene. the colluvium older than the nyt was not found in the sections where the tephra layer is interbedded with the loess. therefore, it is likely that the real top of the loess was contemporaneous with the sedimentation of the colluvium. in the aremogna plain (monte greco massif), at the top of the loess lies a peat layer dated 16,514-14,280 cal a bp (frezzotti & giraudi, 1990a). summing up, the stratigraphy of the sections where the loess was observed, described in previous papers, is very similar to that studied in the new exposures on mount matese. in the deepest depression of a former glacial cirque on mount greco, at an altitude above 2000 m, a 116 fig. 4 a) total alkali (k2o + na2o) vs sio2; b) feotot vs cao and c) mgo vs sio2, for the samples analyzed. along with the chemical data for matese 1 , 2 and 5, the chemical data for tm8a and tm8b for the neapolitan yellow tuff from monticchio (wulf et al., 2004, 2008) and tm9 (correlated with tufi biancastri) are reported for comparison purposes. data for zs98261 and zs98261 are for samples ln1 and ln2 for proximal data (from siani et al., 2001, 2004). late-pleistocene phase of saharan dust deposition in the high apennine mountains (italy) borehole made using a hand auger showed the presence of the quartz-rich loess, lying on glacial debris, covered by volcanic material and soils. in the same cirque, a fresh layer of quartz-rich silt, up to 7 mm thick, was found by one of us (c.g.) at the end of july 1992, in places partially covering short herbs still alive. the dust probably was deposited during a substantial fall of saharan dust, in early march 1991, which covered an area of at least 320,000 km2 stretching from sicily to the south to sweden and finland to the north (stuut et al., 2009). the dust was probably deposited on the snow and during the melting of the snow accumulated in the cirque depression. 4. discussion the set of stratigraphic data and the analysis of the tephra layers show that in the central-southern apennines the sedimentation of quartz-rich loess began at least 27-26k cal a bp and ended in a period bracketed by the fall of the two tufi biancastri tephra layers, that is at the transition between the oldest dryas stadial and the bölling/alleröd interstadial. in some areas, a colluvial reworking of the loess deposits occurred during the period just before and after the fall of the older tufi biancastri (matese 5) tephra, and simultaneously with the final stages of aeolian sedimentation. the sedimentation of colluvia implies geomorphological instability, and suggests, as demonstrated in other apennine massifs (giraudi et al., 2011), cold climatic conditions. as a consequence, we can conclude that the end of the loess sedimentation occurred before the start of the bölling/alleröd interstadial, or, if one refers to the glacial chronology of the apennines, before the venacquaro interstade (giraudi, 2012). the quartz-rich loess, for its mineralogical composition, is an exception among the aeolian deposits found in the mountains of the central-southern apennines. the other late pleistocene and holocene aeolian sediments found in the same massifs (frezzotti & giraudi, 1990a;1990b) have different mineralogical composition. the aeolian sediments, when originated from the deflation of the matrix of fluvial or glaciofluvial deposits, are made up of silt or sandy silt, whitish or light brown in colour, consisting mainly of carbonate. other aeolian sediments made up of silt and sandy silt, predominantly grey and yellowish or brown in colour, and having quite a varied mineralogical composition, derive from tephra layers or from the degradation of soils containing mostly volcanic minerals. late pleistocene loess deposits are well known in northern italy (cremaschi, 1990; rellini et al., 2009) but their geographical distribution ends on the northern slope of the northern apennines. two loess horizons 117 fig. 5 comparison between the phase of sedimentation of the quartz-rich loess on the apennines, quartz variations in the sediment core of the lake vico (modified from narcisi, 2000), apennines glacial phases (modified from giraudi, 2012), stadial and interstadial events in greenland gisp 2 ice core (modified from grootes et al., 1993 and svensson et al., 2006), and terrigenous flux from the sahara in the atlantic site 658c (from demenocal et al., 2000). the tephra layers matese 5 and ln2, formed during the tufi biancastri older eruption, and matese 2 and ln1, formed during the tufi biancastri younger eruption, are reported and plotted with the quartz-rich loess and the chronozones related to the lake prespa sediments (from aufgebauer et al., 2012). explanation of abbreviations: yd= younger dryas; gi-1= greenland interstadial 1; gs-2= greenland stadial 2. giraudi c. et al and interbedded soil have been found on the adriatic slope of the central-northern apennines (chiesa et al., 1990): the younger loess, dated at the upper pleistocene was associated with mousterian artefacts (>40 ka) and therefore older than the loess studied in the present paper. the thickness of the quartz-loess on the various massifs can be used to trace the origin of air masses. the thickness decreases from south to north (frezzotti & giraudi, 1990a; 1990b; giraudi, 1997,1998a,1998b, 2001, 2004) from a maximum thickness of about 70-100 cm on mount pollino (lat. 39°54'n, long. 16°12'e) and mount sirino (40°06'n, 15°52'e), to 10-40 cm on mount matese (41°26'n, 14°24'e), and to 10-30 cm on mount greco (41°47'n, 13°59'e). the thickness is reduced to a few centimetres on the mount velino (42°13'n, 13°25'e). it is therefore possible to assume that the dust has been transported by air masses from the south. today, the dust sedimentation in the mediterranean and in italy is produced by the circulation of southern air masses (guerzoni & chester, 1996; guerzoni et al. 1997). according to prodi & fea (1979); the proximity of italy to north africa and the relief of the italian peninsula favours the fall of saharan dust. the air masses bring dust of saharan origin to the northern shore of the mediterranean sea and, sometimes, to far northern latitudes, as far as sweden and finland (franzén et al., 1994). present saharan dusts are made up mainly of quartz, but carbonates, feldspars and clay minerals are present (lenaz et al., 1986; nihlén et al., 1995; guerzoni et al., 1997; goudie & middleton, 2001). during lgm, quartz of saharan origin were deposited in maar lakes of central italy (narcisi, 2000) and the presence of saharan dust in upper pleistocene sediments and soils is also known for the island of sardinia (andreucci et al., 2012), at the same latitude as central italy. according to stuut et al. (2009) the upper horizon of the terra rossa soils in southern europe and peninsular italy (soil zone d1a) is detached from the lower materials because it is made up of saharan dust, while towards the north (soil zone d1b), the material from saharan dust is incorporated in the soil system and serves only to increase the fine silt content. for the italian peninsula, the limit between the soil systems d1a and d1b is indicated at around 42°n, that is the northernmost latitude where the quartz-rich loess has been recognized. the inflow of saharan dust in the mediterranean marine sediments is well known. in the last million years, the influx of saharan dust has been continuous, but during the glacial periods the quantity of dust was appreciably greater (dinarés-turel et al., 2003). late pleistocene saharan dust deposition in the mediterranean is recognized and dated in marine cores (eriksson, 1979; moreno et al., 2002; bout-roumazeilles et al., 2007). the studies carried out on discontinuous stratigraphic successions on the island of lampedusa, midway between sicily (italy) and north africa (giraudi, 2004b), show that loess, formed mainly by quartz of saharan origin, was sedimented at least during the period between 29-28 cal ka bp and 22-21 cal ka bp and during the late holocene. the presence of a higher percentage of quartz of saharan origin during lgm in continuous sediment cores (fig. 5) from the lago di vico and lagaccione, maar lakes in central italy, (reported by narcisi, 2000; 2001; narcisi & anselmi, 1998), confirms the data from marine cores, the changing percentage of quartz being due to north african alternating phases of aridity and humidity. variations of frequency and intensity of southerly winds carrying saharan dust cannot be excluded. the reported data on saharan dust sedimentation in the mediterranean sea and in peninsular italy strongly support the hypothesis that the quartz-rich loess found on the high apennine massifs was formed mainly by saharan dust, also if its mineralogy and grain size do not exclude the possibility of a local contribution. the pollen of african origin, too, studied by magri & parra (2002), shows that winds coming from africa reached the northern mediterranean shores during some of the periods taken into consideration in the present paper. narcisi (2000; 2001) and narcisi & anselmi (1998), highlight that during the late glacial the sedimentation of aeolian quartz greatly decreased. in particular, at lago di vico, the decrease in quartz is dated between 17,866-16,703 and 13,456-12,888 cal a bp, while at lagaccione it occurred between 16,919-15,847 and 14,138-13,645 cal a bp (radiocarbon dates reported in the papers of narcisi (2000; 2001) and narcisi & anselmi (1998) calibrated using the oxcal 4.2 programme). the strong decrease in the quartz of saharan origin in maar lake deposits corresponds to the end of the sedimentation of loess in the apennines (fig. 5). we think that the only alternative hypothesis on the origin of the loess, e.g. from the continental southern italy or from the exposed continental platform, is not reliable. a northern mediterranean origin of the dust can be excluded because the absence of known atmospheric circulation model that can justify the uplift of a great amount of dust at altitude over 2000 m a.s.l. in the southern italy that acted for millennia. if we do not assume a mainly saharan origin of the loess, we would have to justify and to explain, in terms of atmospherical circulation, the absence of saharan dust on the apennine during the lgm and lateglacial. an independent confirmation on the saharan origin of the loess is given by the chronological correlation with the phases of increase and decrease of the aeolian activity in the sahara. the loess sedimented in the apennines during lgm and late glacial, that is during periods of increased aeolian activity in the sahara (fig. 5) reported by demenocal et al. (2000) and swezey (2001). the age of the end of the sedimentation cannot be statistically distinguished from that of the beginning of the african humid period, dated around 14-15 cal ka bp according to gasse et al. (1987), fontes & gasse,1989), gasse et al. (1990), gasse & fontes (1992), cremaschi (1998), demenocal et al. (2000), gasse (2000), cremaschi (2002). in particular, according to demenocal et al. (2000) who studied the aeolian sedimentation in a core taken in the atlantic ocean west of the sahara desert, the african humid period started around 14,850 cal a bp and was synchronous with the 118 late-pleistocene phase of saharan dust deposition in the high apennine mountains (italy) end of glacial conditions in europe and with the end of the heinrich event 1 (h1) in the north atlantic, that is, with the end of the oldest dryas stadial or the end of greenland stadial gs-2. the start of the african humid period therefore matches the age of the end of the apennine loess sedimentation. it is logical to assume that during lgm and late glacial, up to about the end of the oldest dryas stadial, or greenland stadial gs-2, the italian peninsula was affected by circulation of southern air masses carrying greater amounts of saharan dust. the decreased sedimentation of the saharan dust in the italian peninsula was probably conditioned by the expansion of the vegetation cover in the sahara that occurred during the onset of the african humid period corresponding to the start of the bölling interstadial and, perhaps, by the changes in the circulation of air masses. the increase of aeolian sedimentation in the sahara desert and in the atlantic ocean cores which occurred during the younger dryas (gasse et al.,1987; fontes & gasse,1989; gasse et al.,1990; gasse & fontes,1992; demenocal et al., 2000; gasse, 2000; swezey, 2001) was not recorded in the high apennine massifs. in the apennines, it is possible that the colluvial and aeolian reworking of the nyt tephra prevented the formation of a layer of loess rich in quartz, but it is also possible that something changed in the atmospheric circulation and that the intensity and the frequency of the southern currents remained lower after the oldest dryas-bölling transition. 5. conclusions the study of new exposures on mount matese, in which we recognised a quartz-rich loess with interbedded tephra layers, and the search for quartz in proglacial lake sediments of the central apennines, has enabled us to evidence the correlation between sedimentation of the loess and climatic events recorded in the northern hemisphere, and to hypothesize a saharan origin of most of the dust that forms the aeolian deposit. this saharan origin has been proposed according to the mineralogical composition of the loess and to the observed contemporaneity between the sedimentation of loess in central apennine highs and of saharan dust in central italian maar lakes and in the mediterranean sea sediments. the geochemical characterization of three tephra layers and their dating allowed us to establish that the end of the sedimentation of the loess was contemporary with the beginning of the african humid period and took place at the transition between the oldest dryas stadial (or greenland stadial gs-2) and the bölling/alleröd interstadial (or greenland interstadial gl-1). a greater amount of dust, brought by southerly winds, would have been sedimented during glacial stages, corresponding to periods of increased aridity in north africa. although in the sahara there was a later phase of aridity and an increase of aeolian activity during the younger dryas, in the italian peninsula loess deposits are either not distinctively recognisable or not deposited, because, in that period, the aeolian sediments were diluted by volcanic mineral-rich sediments resulting from the reworking of the tephra layers, or because the southern currents never reached the intensity or frequency of the period preceding the bölling interstadial. references andreucci s., bateman m.d., zucca c., kapur s., aksit i., dunajko a., pascucci v. 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(2012). geochemistry of the campi flegrei (italy) proximal sources for major mediterranean tephras (c-1, c-2, y-3 and y-5). geochimica et cosmochimica acta 93, 102-128. vogel h., zanchetta g., sulpizio r., wagner b., nowaczyk n. (2010) a tephrostratigraphic record for the last glacial-interglacial cycle from lake ohrid, albania and macedonia. journal of quaternary science, 25(3), 320-338 wulf s., kraml m., brauer a., keller j., negendank j.f.w. (2004) tephrochronology of the 100 ka lacustrine sediment record of lago grande di monticchio (southern italy). quaternary international, 122, 7-30. yaalon d.h., ganor e. (1973) the influence of dust on soils during the quaternary. soil science, 116 (3),146-155. zanchetta g., sulpizio r., roberts n., cioni r., eastwood w.j., siani g., caron b., paterne m., santacroce r. (2011) tephrostratigraphy, chronology and climatic events of the mediterranean basin during the holocene: an overview. the holocene, 21(1), 33-52. zanchetta g., giraudi c., sulpizio r., magny m., drysdale r.n., sadori l. (2012) constraining the onset of the holocene “neoglacial” over the central italy using tephra layers. quaternary research, 78, 236-247. late-pleistocene phase of saharan dust deposition in the high apennine mountains (italy) 123 giraudi c. et al 124 late-pleistocene phase of saharan dust deposition in the high apennine mountains (italy) impaginato di donato eeffffeeccttss ooff llaattee pplleeiissttoocceennee--hhoolloocceennee cclliimmaattiicc cchhaannggeess oonn tthhee ppllaannkkttoonniicc ffoorraammiinniiffeerraa iinn tthhee gguullff ooff ggaaeettaa ((ttyyrrrrhheenniiaann sseeaa,, iittaallyy)) vvaalleennttiinnoo ddii ddoonnaattoo dipartimento di scienze della terra università degli studi di napoli “federico ii” tel. 081 5473338 e-mail: valedido@unina.it abstract planktonic foraminiferal assemblages of core g93-c9, recovered in the gulf of gaeta (tyrrhenian sea) at 212 m of depth, were analysed by principal components analysis. the analysis was computed first on raw percentage data and then on logratio transformed data. the most important difference between raw data and logratio data rests in the behaviour of n. pachyderma which in the first case, unlike the second, does not have significant loading on the first component. sea surface temperatures exerted a strong control on foraminiferal assemblages. hydrography and productive system also played an important role in determining composition of assemblages, as shown by the loadings of grazing species on the second component. during the last deglaciation and the early holocene eutrophic conditions allowed globorotalia inflata to expand its distribution toward surface waters of the gulf of gaeta. during the late holocene, planktonic foraminiferal assemblages evidence a tendency towards oligotrophic conditions. riassunto effetti dei cambiamenti climatici tardo pleistocenici-olocenici sui foraminiferi planctonici del golfo di gaeta (mar tirreno, italia). vengono presentati i risultati di una analisi dei componenti principali applicata alle associazioni a foraminiferi planctonici della carota g93-c9, prelevata nel golfo di gaeta a 212 m di profondità. l’analisi è stata effettuata prima sui dati originali e successivamente applicando ad essi una trasformazione logratio per correggere l’effetto della chiusura dei dati percentuali. i risultati ottenuti differiscono principalmente nel carico di neogloboquadrina pachyderma sul primo componente, che risulta quasi nullo con i dati originali e significativo con i dati trasformati. le temperature delle acque superficiali hanno svolto un controllo primario sulle variazioni delle associazioni, in cui si riconoscono chiaramente due gruppi di specie con carichi opposti sul primo componente. i punteggi del primo componente lungo la carota definiscono chiaramente i principali eventi climatici avvenuti durante l’ultima deglaciazione. i carichi sul secondo componente di specie prevalentemente erbivore evidenziano l’effetto di fattori trofici ed idrografici. in particolare tra tardiglaciale e olocene inferiore si instaurano condizioni eutrofiche che consentono a globorotalia inflata, una specie prevalentemente mesopelagica, di proliferare anche in prossimità della costa. viceversa nel corso dell’olocene superiore i risultati evidenziano l’istaurarsi di condizioni oligotrofiche. keywords: planktonic foraminifera, climatic changes, late pleistocene-holocene, tyrrhenian sea, principal components analysis. parole chiave: foraminiferi planctonici, cambiamenti climatici, pleistocene superiore-olocene, mar tirreno, analisi dei componenti principali. il quaternario italian journal of quaternary sciences 1155(2), 2002, 251-257 11.. iinnttrroodduuccttiioonn in the last few decades many studies involving the analysis of foraminiferal assemblages have been carried out on late-pleistocene-holocene sediments in the mediterranean sea, allowing detailed reconstruction of the environmental changes occurred during the last climatic cycles (blanc-vernet et sgarrella, 1989; kallel et al.1997, ariztegui et al. 2000, among others). relatively few studies, however, focus on neritic or coastal environments. an opportunity to study the effect of climatic changes in a neritic milieu was offered by an oceanographic cruise of the o/v urania, in october 1993, during which several cores were collected from the gulf of gaeta continental shelf. the general results of an integrated palaeontological study on three cores (g93c5, g93-c8, g93-c9) involving descriptive analysis of planktonic foraminifera, calcareous nannofossils, pollen and ostracoda, were reported by amore et al. (2000). a detailed analysis of calcareous nannofossil assemblages, involving comparisons with other sectors of the southern tyrrhenian continental shelf, was carried out by esposito (1999). due to its continuous stratigraphical record and good quality of fossil assemblages, core g93-c9 offers the opportunity to examine planktonic foraminiferal assemblages in detail. with a view to examining the responses of foraminiferal assemblages to environmental changes, planktonic foraminifera of core g93-c9 are investigated by principal component analysis (pca). 252 v. di donato 22.. mmaatteerriiaallss aanndd mmeetthhooddss the study area is located within the gulf of gaeta continental shelf, in the southern tyrrhenian sea (fig. 1). the area represents an extension of the volturno river and garigliano river coastal plains. gravity core g93-c9 (lat.41°02’ 4” n, long. 13°32’18”e), 470 cm long, was collected at a depth of 212 m, along an esewsw seismic line. the stratigraphy of core g93-c9, whose sediments consist mainly of clays, is summarised in figure 2. for palaeontological analyses of core g93c9, 47 samples spaced 10 cm apart were collected. samples were washed through a 106 µm sieve. from each sample at least 300 specimens of planktonic foraminifera were collected by using complete splits. the choice of the sieve mesh, which may appear somewhat unusual, requires some explanation. in classical works on oceanic planktonic foraminiferal assemblages large sieve meshes were adopted (i.e. 149 µm) (imbrie & kipp, 1971; among others), obtaining very low percentages of undeterminable specimens. this method, however, also artificially reduces the percentages of small species. at the opposite end, in recent works on mediterranean planktonic foraminiferal assemblages (capotondi, 1999; among others) very small sieve meshes (65 µm) were adopted, obtaining higher (and less biased) abundances of small species. assemblages resulting from treatment with a small sieve mesh, however, contain high percentages of undeterminable specimens and, consequently, a lower number of actual specimens. at the same time the number of censored values (i.e. values below the detection limit) for less abundant larger species distinctly increases, with a negative effect on the accuracy of data (sanford et al., 1993). to avoid such shortcomings it would be necessary to increase the number of specimens counted per sample. by adopting an intermediate sieve mesh (i.e. 106 µm) fewer censored values result, together with only slightly reduced percentages of small species. in order to investigate the relationship among planktonic foraminiferal species, in the present paper assemblages are investigated by means of a pca. the pca was first computed on the raw data and then by applying a logratio transformation (aitchison, 1986; kucera and malmgren, 1998) to the original variables for closure correction. with regards to the foraminiferal species included in the analysis, globoturborotalita tenella and globoturborotalita rubescens were lumped together, while no distinctions were made about neogloboquadrina pachyderma, since it was almost entirely represented by right coiled specimens. no rotations were applied to the components. since in the o r i g i n a l d a t a t h e t h r e e m o s t a b u n d a n t s p e c i e s (turborotalita quinqueloba, globigerina bulloides and globigerinoides ruber) constitute more than the 64% of total assemblages, it was preferred to operate on the correlation matrix rather than the variance-covariance matrix, in order to investigate relationships between less abundant species. the results obtained with logratio transformed data are less affected by the choice of the matrix to be factored. the interpretation of assemblages is based on the present distribution of species (bé & torlderlund, 1971; hembleben et al.1983; pujol and vergnaud grazzini, 1995; among others). the analyses were performed with systat. figure. 1 location map. ubicazione della carota g93-c9. depths in radiocarbon calendar core c9 age source ages ages references (cm) (kyr) (kyr bp) 55 ecozones 2-1 2.8 2.5 capotondi boundary et al. (1999) 75 ecozones 3-2 4.0 3.9 capotondi boundary et al. (1999) 125 ecozones 6-5 10.0 10.9 capotondi boundary et al. (1999) 165 ecozones 7-6 11.4 12.9 capotondi boundary et al. (1999) 170 14c ams dating 12.030±0.100 13.45 (intercept) tab. 1. age sources for core g93-c9. ams c14 dating were calibrated with calib 4.3 (stuiver and reimer, 1994). riferimenti per l’inquadramento cronologico della carota g93c9. la calibrazione delle età radiocarbonio è stata effettuata con calib 4.3 (stuiver and reimer, 1994). 33.. cchhrroonnoossttrraa--ttiiggrraapphhiiccaall ffrraammeewwoorrkk only one ams 14c dating obtained from radiocarbon measurement of globigerinoides spp., globigerina bulloides and orbulina shells, was available for core g93-c9. in order to improve the age model, some events recorded in planktonic foraminifera assemblages were tentatively correlated with the ecozone boundaries of capotondi et al. (1999). the age model is shown in table 1. the climatostratigraphy reconstructed for core g93-c9 by palaeontological proxies (amore et al., 2000) is reported in figure 2. the last glacial period (lg) is represented from the base of the core up to 205 cm. the deglaciation, in which events corresponding with the bølling-allerød and the younger dryas were identified, was recorded in the 205-125 cm interval. the upper part of the core represents the holocene. 44.. rreessuullttss percentages of planktonic foraminifera recorded in core g93-c9 are shown in table 2. tables 3a and 3b show the loadings for the components corresponding to eigenvalues greater than 1, computed respectively from the correlation matrix of the raw and the log transformed data. the most important difference between raw data and logratio data rests in the behaviour of n. pachyderma which in the first case, unlike the second, does not have significant loading on the first component. a minor 253effects of late pleistocene holocene ... 2 6,93 19,1 41,9 7,59 0,33 1,32 0 4,29 0 2,97 8,91 0 1,32 5,28 10 4 21 47,3 5,67 0 2,33 0 1,33 0 5 8,33 0 1 4 20 1,97 24 33,2 6,25 1,64 0,33 0 13,8 0 1,97 4,61 0,66 1,97 9,54 30 8,12 27,9 35,4 6,82 0 3,25 0,65 1,95 0 2,6 1,95 1,95 2,92 6,49 40 4,26 12,8 33,4 5,9 0 0,66 0 10,8 0 5,57 5,25 1,31 5,57 14,4 50 27,2 10,6 27,2 4,32 3,65 8,31 0 6,31 0 2,33 1,99 2,33 1 4,65 60 9,24 19,8 34,3 6,6 0,33 2,31 0 1,32 0 4,95 2,97 12,2 1,32 4,62 70 12,6 27,2 27,5 6,62 0,99 3,31 1,66 0,99 0,33 1,99 2,65 6,62 1,32 6,29 80 5,94 13,2 30,4 11,6 12,9 2,31 1,32 3,63 0 4,62 0,66 1,65 2,64 9,24 90 13,4 21,2 22,7 14 14,3 2,49 0,62 1,56 0 2,8 0 0,93 1,25 4,67 100 9,78 19,9 26,8 18 8,2 0,95 0 2,21 0,95 2,52 0 1,58 0,63 8,52 110 17,4 17,1 22,9 11,3 5,12 4,1 3,41 2,39 2,39 0,68 1,02 1,02 0,34 10,9 120 10 20,7 35 12,3 5 1,33 1 1 0 1 3 0,33 0 9,33 130 26,2 43,7 6,47 9,39 6,47 1,29 0,32 0,65 0,32 0,32 0,32 0 0,32 4,21 140 19,3 19,6 23,5 11,8 8,5 3,59 1,96 0 0 0,33 0 0,98 0,33 10,1 150 27,4 18,2 18,5 7,96 3,18 5,73 8,28 1,27 1,59 0,96 0 0,32 0 6,69 160 24,5 21,2 15,4 13,7 5,23 1,96 3,59 2,61 0,33 0,33 0,65 0 0,65 9,8 170 32,7 14,7 18,7 15 6,67 2,67 0 2,67 0 2 0,33 0,33 0,33 4 180 16,8 22,7 25,3 12,8 1,32 2,63 1,32 1,64 0 2,3 0 0,99 0,33 11,8 190 15,4 19,7 33,1 13,1 0,66 0,98 2,95 0,98 1,31 3,28 0,33 0,66 0,66 6,89 200 20,7 17,7 23 11,7 8,33 1,67 1,33 2,33 0 0,67 0 0 0 12,7 210 28,9 28 9,21 6,58 10,5 5,59 1,32 3,62 1,32 0,66 0,66 0 0 3,62 220 30,8 17,5 8,9 2,05 3,42 9,93 4,45 6,85 5,48 0,68 0 0 0 9,93 230 32 27,5 12 2,27 1,29 5,5 5,5 0 2,59 0 0 0,97 0 10,4 240 33,1 20,4 15,3 5,73 10,5 2,55 2,55 0,96 0,64 0 0 0,32 0 7,96 250 46,5 32,9 1,99 2,99 7,31 1,33 2,33 0,33 1,66 0 0,33 0 0 2,33 260 38,4 22,9 4,52 1,94 1,61 7,42 4,84 4,19 3,87 0,32 0,32 0 0 9,68 270 37,3 26,9 3,57 1,3 5,84 5,84 6,82 0,32 2,27 0 0 0 0 9,74 280 48,4 22,5 3,27 3,59 4,9 0,65 1,96 1,31 0 0 0,33 0 0 13,1 290 42,3 28 6 2,33 4,67 3,33 4,33 0 3,33 0,33 0,33 0 0 5 300 46,4 18,8 0 2,96 1,97 7,89 2,96 1,97 4,93 0 0 0 0 12,2 310 36,2 32,1 2,52 2,83 1,57 6,29 7,23 0,94 1,57 0,31 0 0 0 8,49 320 39,4 38,1 1,28 3,21 7,37 1,92 2,24 0 0,96 0 0 0 0 5,45 330 54 27 1,67 1,67 5,67 4,33 0,33 0,33 2,33 0 0 0 0 2,67 340 31 44,8 5,36 1,53 1,15 5,75 0,77 1,92 2,3 0 0 0 0 5,36 350 34,4 34,1 1,3 1,3 5,19 7,79 6,17 0,97 1,3 0 0 0,32 0 7,14 360 42,7 42,7 1,95 0,65 1,95 2,28 0,98 0 1,3 0 0 0 0 5,54 370 31,9 37,2 7,89 2,84 7,57 5,36 1,26 1,26 0,32 0 0,95 0,63 0 2,84 380 51,5 24,1 0,98 0 1,95 3,58 2,61 0,65 2,28 0 0,33 0 0 12,1 390 34,6 35,9 5,08 0,95 4,44 3,81 7,94 1,59 0,95 0 0 0 0 4,76 400 50,8 31,8 0,66 0,98 5,57 1,31 0,98 0 1,64 0 0 0 0 6,23 410 42,5 31,9 2,66 1,66 6,98 2,66 2,33 1 2,99 0 0 0 0 5,32 420 19,4 37 1,42 2,84 7,11 3,79 1,9 1,42 3,32 0 0 0,47 0 21,3 430 36,5 24,3 2,63 1,64 3,29 15,5 6,25 0,66 3,62 0 0 0,33 0 5,26 440 36,9 39,5 2,33 1,99 7,97 2,66 1,33 0 2,99 0 0 0 0 4,32 450 37,3 38 0,95 2,22 6,65 6,01 0,95 0 3,16 0 0 0 0 4,75 460 31,1 26,2 1,97 5,9 7,54 6,89 0,66 1,31 5,25 0 0 0,66 0,66 11,8 470 47 22,8 0,99 0 2,98 10,6 3,97 1,32 3,97 0 0,33 0 0 5,96 table 2. percentages of planktonic foraminifera within core g93-c9. percentuali dei foraminiferi planctonici della carota g93-c9. cm t u rb o ro ta lit a q u in q u e lo b a g lo b ig e ri n a b u llo id e s g lo b ig e ri n o id e s ru b e r g lo b o ro ta lia in fla ta n e o g lo b o q u a d ri n a p a ch yd e rm a g lo b ig e ri n ita g lu tin a ta n e o g lo b o q u a d ri n a d u te rt re i g lo b o tu rb o ro ta lit a g lo b o ro ta lia s ci tu la o rb u lin a u n iv e rs a g lo b o ro ta lia t ru n ca tu lin o id e s g lo b ig e ri n o id e s sa cc u lif e r g lo b ig e ri n e lla s ip h o n ife ra in d e te rm in a b le difference regards the third component obtained with the logratio transformations, which corresponds to the fourth component of the original data. in figure 2 the scores of the first three components computed from the logratio transformed data are plotted along core g93c9. the following discussion is based on the results achieved with the logratio transformation. 55.. ddiissccuussssiioonn the first three components, corresponding to eigenvalues greater than 1, take into account respectively 55.48%, 10.64% and 8.26% of total variance. the cumulative variance retained is 74.38% of the total variance. as shown in table 3b, the first component clearly individualizes two groups of species, the first of which, characterised by high positive loadings, is constituted by warm water species. the second group consists mainly of cold water species, with high negative loadings. this structure suggests a relation between this component and sea surface temperatures (sst). it can be also observed that in core g93-c9 globigerina bulloides and globigerinita glutinata are grouped with cold water species, while globorotalia inflata is grouped with warm species, as a consequence of its absence during the lg. the comparison of first component scores with algebraic climatic curves for pollen and calcareous nannofossils (figure 3), points out a good agreement in the general trends, supporting the interpretation of the first component in terms of changes in sst. the scores of the first component are lower in the interval corresponding to the lg. the following trend in pc scores points out changes in sst corresponding to the bølling-allerød and 254 younger dryas events of the last deglaciation. the holocene is characterised by increasing values of first component scores. the second component is characterised by high loadings of grazing species, negative for n. pachyderma and g. inflata and positive for globorotalia truncatulinoides (table 3b). the abundance of n. pachyderma, which is usually considered a polar-subpolar species, has been related in the mediterranean sea to the development of eutrophic conditions and a deep chlorophyll maximum (dcm) (rohling and gieskies, 1989; rohling, 1994). the present distribution within the mediterranean sea of g. inflata appears to be related to a rather cool and deep mixing as well as high primary production levels (pujol and vergnaud grazzini, 1995). moreover although g. inflata is mainly a mesopelagic species, it reaches high abundances in shallow water when phytoplankton blooms occur in the mixed layer (pujol and vergnaud grazzini, 1995). in the fossil record this species reaches high abundances during glacial-interglacial transitions (blanc-vernet et al., 1984). as regards g. truncatulinoides, pujol & vergnaud grazzini (1995) suggest that vertical mixing and winter convection are the primary factors controlling the distribution of this species within the mediterranean. in the gulf of salerno g. truncatulinoides, although its percentages never exceed 13%, it is the only grazing species whose abundance increases during the last 5000 yr, when fossil assemblages evidence a decrease in palaeoproductivity (buccheri et al., 2002). on the basis of the above mentioned remarks, the second component may be likely related to trophic conditions and convection in the water column. in practice the highest negative scores reached during the last deglaciationearly holocene interval (fig. 2) could indicate the establishment of eutrophic conditions in the gulf of gaeta. on the contrary positive scores characterise the late holocene, suggesting a decrease in palaeoproductivity. besides the “open water” system of the modern tyrrhenian sea has oligotrophic characteristics (margalef et al. 1966). the opposite relationship between g. inflata and g. truncatulinoides may appear unexpected, as these species are often associated within the mediterranean sea (pujol & vergnaud grazzini, 1995). the positive loading of g. truncatulinoides does not imply an oligotrophic connotation for this species which does not reach high percentages in the late holocene. rather it evidences that during the early holocene environmental conditions were unfavourable for this species. as regards g. inflata, its abundance during the last deglaciation has also been recorded in the shallow core c5 recovered in the gulf of gaeta at a depth of 111 m bsl (amore et al. 2000). this means that during the last deglaciation, when the sea level was about 80-90 m lower than at present (fairbanks, 1989), this species was also abundant in shallower water in the gulf of gaeta. this behaviour probably derived, in addition to advantageous conditions (such as the presence of transitional water masses), also from enhanv. di donato ced primary productivity levels related to increased continental run-off. this is also supported by the high percentages of braarudosphaera bigelowii, a calcareous nannofossil species related to turbidity of surface water and/or low salinity (müller, 1979), recorded within the same interval (esposito, 1999; amore et al., 2000). the composite effect on sea surface temperature changes and trophic regime is highlighted in a plot of core samples on the space defined by first and second components (fig. 4). the plot allows two groups of samples to be distinguished, the first of which comprises samples from the lg and the deglaciation, with an upward trend towards negative scores for the second component. the second group is represented by late holocene samples, with positive scores for both components. the third component is characterised by high positive loadings of globigerinoides sacculifer and negative loadings of globoturborotalita and does not have a clear interpretation. the results of the standardized pca seem to simply highlight the single peak of g. sacculifer within core g93-c9. at present, this tropical species is uncommon within the mediterranean sea, apart from the gulf of lion where this species is very abundant at the pc1 pc2 pc3 pc4 turborotalita quinqueloba -0,883 0,015 -0,105 0,062 globorotalia scitula -0,686 0,416 0,192 0,077 globigerina bulloides -0,563 -0,190 -0,671 0,017 neogloboquadrina dutertrei -0,544 0,336 0,362 -0,219 globigerinita glutinata -0,517 0,571 0,404 -0,131 neogloboquadrina pachyderma -0,180 -0,742 0,351 0,205 globigerinoides sacculifer 0,456 0,121 -0,127 -0,724 globoturborotalita spp. 0,543 0,421 0,142 0,554 globorotalia inflata 0,631 -0,521 0,434 -0,087 globorotalia truncatulinoides 0,723 0,347 -0,317 0,146 globigerinella siphonifera 0,779 0,238 -0,053 0,203 orbulina universa 0,909 0,133 0,029 -0,118 globigerinoides ruber 0,944 0,025 0,087 -0,111 eigenvalues 5,909 1,857 1,252 1,044 percent of total variance explained 45,452 14,288 9,633 8,032 table 3a component loadings, eigenvalues and percent of total variance for pca computed from raw data. component loadings, autovalori e percentuale della varianza totale per l’analisi dei componenti principali relativa ai dati percentuali pc1 pc2 pc3 turborotalita quinqueloba -0,913 -0,025 0,045 globorotalia scitula -0,867 0,210 0,014 neogloboquadrina dutertrei -0,799 -0,041 -0,066 globigerinita glutinata -0,735 0,279 0,061 globigerina bulloides -0,692 0,076 0,265 neogloboquadrina pachyderma -0,620 -0,584 -0,163 globoturborotalita spp. 0,493 0,351 -0,686 globigerinoides sacculifer 0,538 -0,069 0,638 globorotalia inflata 0,596 -0,678 -0,114 globorotalia truncatulinoides 0,643 0,488 0,025 globigerinella siphonifera 0,806 0,183 0,271 globigerinoides ruber 0,829 -0,228 -0,042 orbulina universa 0,904 0,020 -0,011 eigenvalues 7,083 1,383 1,074 percent of total variance explained 54,481 10,638 8,259 table 3bcomponent loadings, eigenvalues and percent of total variance for pca computed from logratio transformed data. component loadings, autovalori e percentuale della varianza totale per l’analisi dei componenti principali dei dati sottoposti a una trasformazione logratio. 255 end of summer (pujol and vergnaud-grazzini, 1995). according to bé and tolderlund (1971) this species is more abundant in sea surface waters with intermediate salinities, while the maximum abundance of g. ruber occurs at more extreme salinities, as in the present-day mediterranean sea. the highest abundances of g. sacculifer and consequently highest positive scores of the third component in core g93-c9 are reached around 3.5 kyr. this peak, which has been recognised throughout the western mediterranean (capotondi et al. 1999) coincides, in the gulf of salerno, with the re-entry of styliola subula, a halophile pteropod. buccheri et al. (2002) relate this event to the increase in sea surface salinity following the end of the sapropel s1 stagnation phase. the present distribution of g. sacculifer suggests that its abundance peak could be related to an enhanced influx of atlantic waters after the end of the s1 stagnation phase, with sea surface salinities higher compared with the stagnation phase, but lower in comparison to the present. 66.. ccoonncclluussiioonnss the results of a pca of planktonic foraminiferal assemblages of gulf of gaeta, applied first to the raw percentages data and then to the logratio transformed data, differ primarily in the behaviour of n. pachyderma, which has no significant loading on the component related to sst if the pca is computed from the raw data. this result is analogous to that obtained by blancvernet and sgarrella (1989) in tyrrhenian and adriatic sea cores. however if data are corrected for closure the same species achieves a negative loading on the same component. apart from the strong influence exerted by changes in sst, hydrography and trophic regime also play an important role in determining composition of assemblages. in particular second component scores indicate the establishment of eutrophic conditions during the last deglaciation and the early holocene which allowed g. inflata to expand its distribution toward shallow waters of the gulf of gaeta. by contrast the late holocene is characterised by a tendency towards the establishment of oligotrophic conditions. aacckknnoowwlleeddggeemmeennttss i wish to thank prof. giuliano ciampo and dr. paola esposito for their reviews of the work and their constant support. thanks are also due to an anonymous reviewer for his critical and constructive comments. effects of late pleistocene holocene ... figure 2 stratigraphy of core g93-c9 and scores of the first two component of foraminiferal assemblages. carota g93-c9. stratigrafia, climatostratigrafia e punteggi dei primi due componenti principali delle associazioni a foraminiferi planctonici. 256 v. di donato figure 4 plot of core samples on the space defined by first and second components. numbers refer to depth in core g93-c9. grafico dei campioni della carota g93-c9 nello spazio definito dai primi due componenti. figure 3 first component scores of planktonic foraminiferal assemblages compared with algebraic climatic curves for pollen and calcareous nannofossils (from amore at al. 2000). raffronto tra i punteggi del primo componente delle associazioni a foraminiferi planctonici e le curve climatiche algebriche di pollini e nannofossili calcarei. first component s e co n d c o m p o n e n t rreeffeerreenncceess aitchison, j., 1986. the statistical analysis of compositional data. chapman & hall, new york, 416 pp. aritzegui, d., asioli, a., lowe, j.j., trincardi, f., vigliotti, l., tamburini, f., chondrogianni, c., accorsi, c.a., bandini mazzanti, m., mercuri, a.m., van der kaars, s., mckenzie, j.a. and oldfield, f., 2000. paleoclimate and the formation of sapropel s1: inferences from late quaternary lacustrine and marine sequences in the central mediterranean region. palaeogeogr. palaeoclimatol. palaeocol. 158, 215-240. amore, f.o., ciampo, g., di donato v., esposito, p., russo ermolli, e. and staiti, d., 2000. an integrated micropalaeontological approach applied to late pleistocene-holocene palaeoclimatic and palaeoenvironmental change (gaeta bay, tyrrhenian sea). in: hart, m.b. (editor), climates: past and present. geological society, london, special publications, 118811: 95-111. bé a.w.h. and tolderlund d.s., 1971. distribution and ecology of living planktonic foraminifera in surface waters of the atlantic and indian oceans. in: b.m. funnell and w.r.riedel (editor), the micropaleontology of the oceans. cambridge university press, london, 105-149. blanc-vernet l. and sgarrella f., 1989. assemblages de foraminiferes planctoniques en mer tyrrhénienne et en mer adriatique pendant les derniers 130000 ans. implications paléoécologiques. paleogeogr., paleoclimatol., palaeoecol., 7766: 107-124. blanc-vernet l., sgarrella f. et acquaviva m., 1984. évènements climatiques,hydrologie et foraminifères en méditerranée au quaternarie recent. bull. soc. géol. france, xxxxvvii,, 77:12351243. buccheri g., capretto g., di donato v., esposito p., ferruzza g., pescatore t., russo ermolli e., senatore m.r., sprovieri m., bertoldo m., carella d. and madonia g., 2002. a high resolution record of the last deglaciation in the southern tyrrhenian sea: environmental and climatic evolution. marine geology, 118866: 447-470. capotondi, l., borsetti, a. and morigi, c., 1999 foraminiferal ecozones, a high resolution proxy for the late quaternary biochronology in the central mediterranean sea. marine geology, 115533 ((1144)): 253-274 esposito, p., 1999. le associazioni a nannoplancton calcareo del pleistocene superiore-olocene dei golfi di gaeta, pozzuoli e salerno (mar tirreno). biocronologia e ricostruzione paleoclimatica. tesi di dottorato, università federico ii, napoli, 164 pp. fairbanks r.g., 1989. a 17,000 year glacio-eustatic sea level record: influence of glacial melting rates on the younger dryas event and deep ocean circulation. nature, 334422: 637-642. hembleben ch., spindler m. and anderson o.r., 1989, modern planktonic foraminifera. springer-verlag imbrie, j and kipp, n.g. 1971, a new micropaleontological method for quantitative paleoclimatology: application to a late pleistocene caribbean core. in: k. tukerian (editor), the late cenozoic glacial ages. yale univ. press., new haven, 71-191. kallel, n., paterne, m., labeyrie, l., duplessy, j.c. and arnold,m., 1997. temperature and salinity records of the tyrrhenian sea during the last 18 000 years. paleogeogr. paleoclimatol. palaeoecol. 113355:: 97-108. kucera m. and malmgren b.a., 1998. logratio transformation of compositional data – a resolution of the constant sum constraint. marine micropaleontology, 3344: 117-120 margalef r., herrera j., steyaert m. et steyaert j., 1966. distribution et charactéristiques des communautés phytoplanctoniques dans le basin tyrrhénien de la méditerranée en function des facteurs ambiants et à la fin de la stratification estivale de l’année 1963. bull. inst. r. sci. nat. belg., 4422: 1-56 müller c., 1979. les nannofossiles calcaires. la mer pelagienne, 210-220. pujol c. and vergnaud-grazzini c.,1995. distribution patterns of live planktic foraminifers as related to regional hydrography and productive systems of the mediterranean sea. marine micropaleontology, 2255: 187-217 rohling, e.j., 1994. review and new aspects concerning the formation of eastern mediterranean sapropels. marine geology. 112222: 1-28. rohling e.j. and gieskes w.w.c., 1989. late quaternary changes in mediterranean intermediate water density and formation rate . paleoceanography, 44: 531-545. sanford r.f., pierson c.t. and crovelli r.a., 1993. an objective replacement method for censored geochemical data. mathematical geology, 2255 ((11)):: 5979. stuiver, m. and reimer, p. j., 1993. extended 14c database and revised calib radiocarbon calibration program. radiocarbon,, 3355: 215-230. 257effects of late pleistocene holocene ... ms. ricevuto il 30 luglio 2002 testo definitivo ricevuto il 7 gennaio 2003 ms. received: july 30, 2002 final text received: january 7, 2003 impaginato cocco lliinneeaammeennttii mmoorrffooddiinnaammiiccii ee sseeddiimmeennttaarrii ddeell lliittoorraallee ddeeii ccaammppii fflleeggrreeii ((ccaammppaanniiaa,, iittaalliiaa mmeerriiddiioonnaallee)) eennnniioo ccooccccoo11,, yyoonnee iiaaccoonnoo22,, ssaabbaattoo iiuulliiaannoo22 && mmaarriiaa rroossaarriiaa lliissttaa22 1dipartimento di scienze della terra, università “federico ii”, napoli. e-mail: encocco@unina.it 2c/o dipartimento di scienze della terra, università “federico ii”, napoli riassunto l’area in esame può essere suddivisa in tre settori a caratteri nettamente differenziati, il litorale di cuma, che ne segna il limite occidentale, il golfo di pozzuoli, che ne costituisce la fascia orientale più complessa ed articolata ed il litorale di miliscola che ne rappresenta il raccordo centrale. il litorale di cuma. esteso per oltre 6 km con orientamento n-s, questo settore costituisce la porzione terminale della piana costiera del f. volturno, la cui foce è situata circa 20 km più a nw. le spiagge basse e sabbiose sono limitate verso l’interno da cordoni dunari in parte allo stato naturale ed in parte fortemente antropizzati. l’evoluzione recente (periodo 1980-1998) è marcata da un arretramento generalizzato nel periodo 1980-1987 seguito da una tendenza all’avanzamento nel successivo periodo 1987-1998, con valori decrescenti procedendo da n verso s. il litorale di miliscola. si estende con orientamento w-e per circa 2 km tra i promontori di monte di procida e di capo miseno ed è limitato verso l’interno da un lago costiero (lago di miseno). in conseguenza ad una forte crisi erosiva che aveva colpito l’area alla metà degli anni ’70 sono state costruite tra il 1980 e il 1988 otto piattaforme-isole che hanno indotto un'accentuata ricostituzione della spiaggia a tergo delle opere; nella parte orientale del settore (verso capo miseno), dove tali opere sono assenti, si instaura una tendenza di tipo erosionale. il golfo di pozzuoli. esteso per oltre 9 km, configura due ampie falcature semicircolari ad andamento e-w, costituite da coste alte e rocciose alternate a coste basse e sabbiose di limitata ampiezza. profonde sono le modificazioni naturali ed antropiche rilevabili in questo settore: tra le prime si ricordano i fenomeni bradisismici che hanno interessato l'area fin dall'antichità portando alla sommersione di notevoli porzioni di territorio litoraneo, tra le seconde una urbanizzazione talmente spinta da stravolgere completamente l’assetto geoambientale naturale della fascia costiera. abstract morphodynamical and sedimentary features of the coast of the phlegrean fields (campania, southern italy). the phlegrean fields are one of the most famous volcanic areas in the world. during the last 50,000 years this area has been formed by the activity of many eruptive centres and today it has the typical morphology of a volcanic field. at present the phlegrean fields are active, even if the last event was recorded a long time ago: the monte nuovo eruption in 1538. the endogenous activity is currently recorded by the frequent inversions of the vertical crustal movements (bradyseism), by the sismicity connected to the bradyseismic events and by the intense thermal activity. from the roman age up to this time the features of the bradyseismic events have not been defined yet because of the type and complexity of the phenomena; recent research shows that the greatest submersion (17÷18 m) was verified during the early middle ages. after the resurgence phase the ground has risen only 6÷7 m: the presence of the submerged roman ruins shows the extent of the sinking.the coastal area could be divided into three clearly diversified sectors: the shore of cuma constituting the western boundary; the gulf of pozzuoli representing the eastern zone, more complex and articulate; the shore of miliscola, the central connection between the two preceeding sectors. the shore of cuma.this sector, extending for about 6 km with n-s orientation between licola mare and monte di procida promontory, constitutes the terminal part of the coastal plain of the volturno river, which flows approximately 20 km to the nw. the low and sandy beaches are limited inland from some foredune ridges, partly natural and partly urbanized. in the northern sector, behind the foredune ridges, there is a wide swampy area reclaimed during the last century ("mazzoni area and licola lake") and in the southern sector there is the fusaro coastal lake. in the central part the promontory of cuma interrupts the outline of the coast; this promontory was the centre of the acropolis during the greek-roman age, but today the acropolis has almost entirely disappeared. within the depth of 5 m the submarine beach shows one or two bar-trough systems: the inner one is crescentic and frequently connected to the rhythmic topography of the shoreline, while the outer one is linear and situated at a distance of about 100 m from the coast. a gentle slope characterizes the submarine beach beyond the bar-trough zone. the evolution of the shoreline presents a general erosional tendency during the years 1980-1987, whereas a tendency to the progradation is evident during the years 1987-1998. the prevailing wind sector is delimited by the 180°-330°n azimuth; most storms are come in from the 270°-300°n sector. the shore of miliscola.the shore of miliscola is situated between the monte di procida and capo miseno promontories and has an extension of approximately 2 km; it is limited inland from the miseno coastal lake. in the western tract we can find various defence works, while in the eastern tract a wide beach is evident. the submarine beach is characterized by a small bar-trough system within the 3 m depth and within a distance of less than 75 m from the coast. eight circular breakwaters have been built from 1980 to 1988 because of strong erosion during the middle '70ies; in these years these defence works have brought an evident beach restoration. after which, until 1996, the shoreline position behind the breakwaters has remained substantially unchanged, while in the eastern part of the sector (toward capo miseno) an erosional tendency was observed with a value of 0.5 m/y. the gulf of pozzuoli.this sector, extending for over 9 km and forming two large semi-circular zones with an w-e orientation, shows high and rocky coasts alternated with small, low sandy beaches. the prevailing wind sector is delimited by the 120°n and the 200°n azimuth; the significant waves come by the 120°-130°n and 180°n azimuth; the maximum fetch and the greatest energetic potential concerns the 180°n azimuth. in this area the modifications are very evident, natural as well as and anthropic. among the natural ones there are the bradyseismic events, that have caused the submersion of entire coastal tracts (for instance: the structures of the portus iulius, the harbour of the ancient roman imperial navy) and the monte nuovo eruption in 1538, that changed the coastal configuration in the western zone of the gulf. among the anthropic ones there is a strong urbanization (“ilva” iron and steel industry, various defence work, artificial coastal platforms) that has completely destroyed the natural environment of the area. parole chiave: processi morfodinamici, distribuzione dei sedimenti, variazioni della linea di riva, interventi antropici, bradisismo. keywords: nearshore morphodynamics, sediment distribution , shorelines changes, human activities, bradyseism. il quaternario italian journal of quaternary sciences 1155(2), 2002, 209-220 210 e. cocco et alii 11.. pprreemmeessssaa in questa nota vengono riportati i risultati delle indagini condotte lungo il litorale dei campi flegrei (campania) nel periodo 1996-98 nell’ambito del prog. strategico cnr “ambiente e territorio”, sottoprog. “sistemi naturali ed antropici”. in maggior dettaglio sono stati eseguiti 25 transetti batimetrici ortogonali alla costa entro la profondità di 15 m, prelevati ed analizzati 68 campioni di sedimenti di fondo subsuperficiali e determinate le principali caratteristiche dinamico-evolutive (parametri ondosi e variazioni recenti della linea di riva). e. cocco ha coordinato le ricerche, occupandosi in particolare degli aspetti relativi ai fenomeni bradisismici e della stesura finale del testo; y. iacono e s. iuliano hanno eseguito le varie campagne di rilevamento curando rispettivamente gli aspetti sedimentologici e quelli morfoevolutivi; m.r. lista si è interessata della cartografia storica e delle modificazioni antropiche. i campi flegrei costituiscono un'area vulcanica tra le più famose nel mondo. formatasi nel corso degli ultimi 50.000 anni (rosi & sbrana, 1987) attraverso numerosi centri eruttivi che le hanno conferito la caratteristica morfologia di un campo vulcanico, l'area è ritenuta attiva sebbene sia stata registrata una sola manifestazione effusiva in epoca storica: l'eruzione del monte nuovo nel 1538. l’attività endogena non sopita è segnalata dalle frequenti inversioni del moto del suolo (bradisismo), dalla sismicità che accompagna le crisi bradisismiche e dalle intense manifestazioni termali. per quanto riguarda l’evoluzione del fenomeno bradisismico dall’epoca romana ad oggi, gli studi più recenti (cinque et al., 1991; di vito & luongo, 1993; russo et al., 1998; milia et al., 2000) indicano che la maggiore sommersione si è verificata in epoca alto medioevale superando i 17÷18 m dei quali solo 6÷7 sono stati recuperati in seguito alle successive fasi ascensionali (la testimonianza di uno sprofondamento così vistoso è data dalla presenza di ruderi romani a varie profondità nell’area di baia e miseno). 22.. ccaarraatttteerrii mmoorrffooddiinnaammiiccii ee sseeddiimmeennttaarrii l’area in esame può essere suddivisa in tre settori a caratteri nettamente differenziati, il litorale di cuma, che ne segna il limite occidentale, il golfo di pozzuoli, che ne costituisce la fascia orientale più complessa ed articolata ed il litorale di miliscola che ne rappresenta il raccordo centrale (fig. 1). 22..11 iill lliittoorraallee ddii ccuummaa esteso per oltre 6 km con orientamento n-s tra licola mare ed il promontorio di monte di procida, questo settore costituisce la porzione terminale della piana costiera del f. volturno, la cui foce è situata circa 20 km più a nw; le spiagge basse e sabbiose sono limitate verso l’interno da cordoni dunari in parte allo stato naturale ed in parte fortemente antropizzati (fig. 2), cui fanno seguito, a n, una vasta area acquitrinosa bonificata nel secolo scorso (“mazzoni, lago di licola”) ed a s il lago costiero del fusaro. il profilo della costa è interrotto nella parte centrale dal promontorio di monte di cuma, sede dell’antica acropoli di epoca romana (nulla, o quasi, rimane della città greca, la più antica d’italia vallet, 1990). l’assetto morfologico dei fondali antistanti il litorale di cuma è stato delineato mediante l’elaborazione di 6 profili batimetrici eseguiti ad interasse medio di 400 m, fino alla profondità di 10 m. la spiaggia sottomarina presenta, entro la profondità di 4 m, uno o due sistemi di barra-truogolo con la cresta barra ad una profondità compresa tra 1,3 e 2,6 m (figg. 3a e 3b); la barra interna risulta festonata e collegata alle ondulazioni ritmiche della linea di riva (sand waves cocco, 1976), mentre quella esterna è più rettilinea, ad una distanza di un centinaio di metri dalla battigia. le pendenze dei fondali sono inferiori all’1 % fino alla profondità di circa 1 m, per poi passare, in corrispondenza della zona del secondo ordine di barre, a valori compresi tra 1 e 2,5 %; oltre l’isobata dei 3 m le pendenze si addolciscono e, fino ai -10 m, sono comprese nell’intervallo 0,5÷1 % (fig. 4). si ricorda che nell'area immediatamente a s del promontorio di monte di cuma era posizionato secondo l’ipotesi di paget (1968) l'antico porto romano oggi obliterato da colluvioni e da materiale vulcanico; recenti indagini (vecchi et al., 2000) tendono ad ubicare il porto nella parte settentrionale del promontorio, in corrispondenza del lago di licola, oggi bonificato. l'analisi delle variazioni recenti della linea di riva (fig. 5) condotta attraverso il confronto aerofotografico (levate del 1980, 1987 e 1998) evidenzia tre zone a fig. 1 ubicazione dell’area in studio. location of the study area. 211lineamenti morfodinamici e sedimentari ... fig. 4 litorale di cuma. carta delle isobate del tratto compreso tra foce fusaro e torre gaveta. the shore of cuma. bathymetric map of the sector between foce fusaro and torre gaveta localities. fig. 2 litorale di cuma. ad un’ampia spiaggia fa seguito un cordone dunare più o meno antropizzato. sullo sfondo il promontorio di monte di cuma. the shore of cuma. the backshore is followed inland by a foredune ridge more or less affected by human activities. in the background the monte di cuma promontory. fig. 3 litorale di cuma. profili batimetrici della spiaggia sommersa (ecografo elac-laz 721 munito di trasduttore a 200 khz; le linee orizzontali indicano gli intervalli di profondità ogni 4 m): aprofilo ad un solo sistema di barre (p24, fig. 4); bprofilo a doppio ordine di barre (p22, fig. 4). the shore of cuma: bathigrams of submarine beach. an echographer model elac-laz 721 with a frequency of 200 khz transducer was used, the horizontal lines indicate the 4 m depth intervals; asingle bar and trough profile (p24, fig. 4); bdouble bar and trough profile (p22, fig. 4). 212 diversa evoluzione -rispettivamente comprese tra i punti di riferimento 1…7, 8…20 e 21…33caratterizzate da una tendenza generalizzata all’arretramento nel periodo 1980-1987 e da una tendenza generalizzata all’avanzamento nel successivo periodo 1987-1998, sempre con valori decrescenti procedendo da n verso s. in particolare per il primo periodo i valori di arretramento medio risultano rispettivamente pari a 4,6 m, 1,8 m e 0,5 m per anno nelle tre zone citate, per il secondo periodo i valori di avanzamento medio risultano pari a 2,5 m, 1,4 m e 0,4 m per anno, sempre per le medesime aree. l'arretramento evidenziato nel 1987 può essere attribuito alla mareggiata eccezionale che ha colpito la costa del tirreno meridionale nel mese di gennaio. per quanto riguarda il regime meteomarino, il settore di traversia risulta compreso tra 180°n e 330°n, il fetch massimo è pari a 401 miglia nautiche (direttrice 240°n), le ondazioni di maggiore frequenza ed intensità (1350 eventi su un totale di 1820) provengono dal subsettore 270°300°n (tab. 1). l’altezza d’onda media di modellamento è compresa tra 0,7 e 2,16 m, l’altezza massima per un periodo di ritorno trentennale è pari a 7,18 m (direttrice 250°n). 22..22 iill lliittoorraallee ddii mmiilliissccoollaa si estende per circa 2 km con orientamento w-e tra i promontori di monte di procida e di capo miseno (fig. 6) ed è limitato verso l’interno da un lago costiero (lago di misenomaremorto). il tratto occidentale è caratterizzato da una serie di opere marittime a varia tipologia (8 piattaforme-isole, 3 scogliere aderenti, 1 pennello ed 1 foce armata) a difesa di una spiaggia di ampiezza ridotta, mentre quello orientale configura una profonda falcatura con una spiaggia emersa ampia fino a 70 m. i caratteri morfologici della spiaggia sommersa sono stati delineati mediante l’esecuzione di 9 profili batimetrici ad interasse di circa 200 m fino alla profondità di 10 m (figg. 7 e 8): nella parte occidentale la morfologia è fortemente condizionata dalla presenza delle otto piattaforme-isole, che conferiscono ai fondali un andamento irregolare con pendenze variabili tra 1 e 4 %; nella parte orientale, dove le piattaforme mancano, i fondali risultano caratterizzati da un sistema barra truogolo poco sviluppato entro la profondità di 3 m ad una distanza dalla battigia non superiore a 75 m. oltre la profondità di 3 m e fino a -10 m la morfologia si regolarizza in tutto il settore, con pendenze come. cocco et alii tab. 1 litorale di cuma. principali caratteristiche del moto ondoso. modello previsionale smb (c.e.r.c., 1984), dati di vento rilevati alla stazione di ponza nel periodo 1951-1981. the shore of cuma. main feature of wave climate (smb method, wind data recorded at the ponza st. during fig. 5 litorale di cuma. diagramma delle variazioni della linea di riva nel periodo 1980-1998. i punti di riferimento presentano un intervallo di circa 300 m, procedendo da n verso s; i punti 9...15 marcano la spiaggia antistante il promontorio di monte di cuma. the shore of cuma. shoreline changes during the 1980-1998 period. reference points 9…15 mark the shore in front of the monte di cuma promontory. 213 prese tra 0,5÷1 % (lato piattaforme-isole) e 1,5÷2 % (lato capo miseno). la spiaggia di miliscola costituiva, fin dall’epoca romana, il limite meridionale dei due bacini portuali della flotta augustea: il bacino interno (maremorto) fungeva da cantiere navale, quello esterno -la baia di misenocostituiva il porto vero e proprio. il nome della spiaggia deriva da “militium schola”, cioè il campo di esercitazione e di addestramento delle reclute, ricordata come “schola armaturarum” in una iscrizione del iv sec. d.c. ivi rinvenuta. da rilevare che, secondo cinque et al. 1991, anche quest’area, oltre a quelle classiche di baia e pozzuoli, è stata soggetta a movimenti bradisismici, come testimoniato dalla successione stratigrafica dei terreni che seppelliscono i resti del complesso termale di misenum della prima metà del ii sec. d. c., posti all’estremità sud orientale della spiaggia di miliscola. l’area misenate avrebbe registrato, tra la fine del vii sec. ed il ix-x sec. d. c., un abbassamento di circa 11÷12 m. l’equilibrio dinamico della spiaggia ha incominciato ad alterarsi allorquando negli anni ‘50/60 si è proceduto al prolungamento del canale di comunicazione tra il bacino di maremorto (lago miseno) ed il mare: tale canale, fungendo da pennello, ha provocato un repentino arretramento (13 m nel periodo 1965-1974) dell’arenile di sottoflutto, posto ad est. sul litorale in erosione si è abbattuta nel 1976 una violenta mareggiata talché si è proceduto alla realizzazione di un progetto organico di difesa attraverso la messa in opera di barriere radenti e di otto piattaforme-isole tra il 1980 ed il 1988 (figg. 6 e 9). il progetto originale, mai ultimato, prevedeva la realizzazione di una nona piattaforma-isola e di due pennelli collegati alla piattaforme più esterne, la prima e la nona. il confronto cartografico (fig. 9) ha messo in evidenza, per il periodo19781986, un'accentuata ricostituzione della spiaggia nell’area “protetta” dalle opere di difesa; con valori medi di avanzamento pari a 3 m per anno; ad est delle opere (zona di sottoflutto) la lineamenti morfodinamici e sedimentari ... fig. 6 panoramica del litorale di miliscola. al centro della foto si può osservare la foce armata del canale di comunicazione con il lago miseno (a sinistra); sullo sfondo capo miseno. the shore of miliscola towards capo miseno. note the various defence works (jetties, seawalls and detached breakwaters) in the western part of the shore. fig. 7 litorale di miliscola. profili batimetrici della spiaggia sommersa (v. fig. 3): aprofilo senza barre (p12, fig. 8); bprofilo ad un solo ordine di barre (p16, fig. 8). t he shore of m i l i s c o l a . bathigrams of submarine beach (see fig. 3): ano bar profile (p12, fig. 8); bsingle bar and trough profile (p16, fig. 8). 214 riva configura una repentina falcatura di erosione quindi, procedendo verso capo miseno (grotta dragonara), si osserva una debole tendenza alla progradazione. nel periodo 1986-1996 la posizione della linea di riva a tergo delle piattaforme-isole è rimasta sostanzialmente immutata, eccezion fatta per l'area a tergo delle ultime due piattaforme -posizionate proprio tra il 1986 ed il 1988dove si verifica un notevole ripascimento (5 m/a). nella parte orientale del settore (verso capo miseno), dove tali opere sono assenti, si instaura una tendenza di tipo erosionale con valori di arretramento nell’ordine di 0,5 m/a. 22..33 iill ggoollffoo ddii ppoozzzzuuoollii esteso per oltre 9 km, configura due ampie falcature semicircolari ad andamento e-w, separate dalla falesia di rione terra (centro storico di pozzuoli); la costa si presenta alta e rocciosa alternata a spiagge basse e sabbiose limitate talvolta verso l’interno da laghi costieri (lucrino). nell’area occidentale del golfo -litorale di lucrino, fig. 10sono stati eseguiti 10 profili batimetrici (figg. 11 e 12) e prelevati 68 campioni di sedimenti di fondo mobile entro la profondità di 10 m. i fondali si presentano con pendenze minori del 2% fino ai 5 m di profondità e con pendenze comprese tra 2 e 6 % a profondità maggiori (fig. 12). seguendo la metodologia di dias & neal (1990) i sedimenti sono risultati per il 77% polimodali (fino ad un massimo di 6 mode), la maggiore frequenza è rappresentata dalla trimodalità (26%); sottoriva sono presenti sedimenti ad 1÷2 mode, procedendo verso il largo prevale la polimodalità (fig. 13). l’applicazione di analisi statistiche (iacono et al., 1998) ha permesso da un lato (cluster analysis) di individuare tre gruppi omogenei di sedimenti caratterizzati dal raggruppamento di campioni a simile contenuto di silt, sabbia e ghiaia e dall’altro (biplot analysis) di legare l’esistenza dei tre gruppi con la loro composizione granulometrica prevalente permettendo di individuare le relazioni campioni-granulometria in modo più specifico. in particolare queste analisi hanno evidenziato che i sedimenti della porzione occidentale del golfo di pozzuoli sono caratterizzati da un corpo principale prevalentemente sabbioso che talvolta si arricchisce in termini siltosi -rinvenibili in aree a bassa energia riparate dal moto ondoso o a profondità superiori a 10 me talvolta si arricchisce in termini ghiaiosi rinvenibili in ambiente ad alta energia (sottoriva). quando questi ultimi sedimenti si rinvengono a profondità comprese tra 5 e. cocco et alii fig. 8 litorale di miliscola: carta delle isobate. the shore of miliscola: bathymetric map. fig. 9 litorale di miliscola. variazioni della linea di riva nel periodo 1978-1996 (dalla cartografia del comune di bacoli in scala 1:10.000). the shore of miliscola. shoreline changes during the 1978-1996 period. e 15 m, come nel caso in esame, testimoniano spiagge relitte. la mobilitazione dei sedimenti avviene prevalentemente per long shore current da e verso w, come è confermato dalla configurazione asimmetrica della linea di riva nei pressi dei numerosi pennelli presenti nell’area di lucrino. si ricorda che studi precedenti (cocco et al., 1988a, 1988b) avevano evidenziato la presenza di antiche spiagge sommerse di epoca romana, marcate nell’area di pozzuoli dalle strutture archeologiche del portus julius (il porto della flotta imperiale romana) alla profondità di circa 3 m (v. figg. 14 e 15) e che i sedimenti presenti nella spiaggia sottomarina e nei fon215lineamenti morfodinamici e sedimentari ... fig. 10 panoramica del litorale di lucrino limitato verso l’interno dal lago di lucrino. sullo sfondo, a destra, il vulcano di monte nuovo. the shore of lucrino, limited inland by lucrino lake. in the background, on the right, we can observe the monte nuovo volcano. fig. 11 litorale di lucrino. profili batimetrici della spiaggia sommersa (v. fig. 3): aprofilo a doppio ordine di barre (p2, fig. 12); bprofilo senza barre (p4, fig. 12); cprofilo con i ruderi sommersi del “portus julius” (p8, fig.12) che indicano l’antica linea di costa di epoca romana alla profondità di 4 m (v. fig. 15). the shore of lucrino. bathigrams of submarine beach (see fig. 3): adouble bar and trough profile (p2, fig. 12); bno bar profile (p4, fig. 12); cprofile with the ruins of “portus julius” (p8, fig.12) that show the ancient coastline during the roman age at the –4 m depth (see fig. 15). dali entro la profondità di 30 m erano costituiti esclusivamente da sabbie da molto fini a molto grossolane, con una dispersione delle frazioni più sottili dalle aree centrali del golfo sia verso w che verso e. la presenza di sabbie grossolane a profondità superiori a 10÷12 m era stata correlata proprio ai depositi relitti delle antiche spiagge. dal punto di vista meteomarino, il settore di traversia del golfo di pozzuoli (porzione occidentale, litorale di lucrino) risulta compreso tra 120°n e 200°n (tab. 2), i fetches sono compresi tra 1 e 20 miglia nautiche, fatta eccezione per la direttrice 180°n cui corrisponde l’estensione di 162 m.n. ed una frequenza molto alta degli eventi (141 su un totale di 704, pari al 20%). l’altezza d’onda media di modellamento è compresa tra 0,66 e 1,38 m, l’altezza massima per un periodo di ritorno trentennale è pari a 3,78 m (direttrice 170°n). 22..33..11 llee mmooddiiffiiccaazziioonnii nnaattuurraallii la costa flegrea negli ultimi due millenni è stata oggetto di ripetute sommersioni da parte del mare a causa dei moti bradisismici con forti modificazioni della topografia costiera (figg. 14 e 15). grazie allo studio condotto sui fori di litodomi riscontrati sulle colonne del serapeo di pozzuoli (parascandola, 1947) è stato stabilito che l’area flegrea sia iniziata a sprofondare già dal i-ii secolo d.c.; questa fase di moto discendente 216 e. cocco et alii fig. 12 litorale di lucrino. carta delle isobate. the shore of lucrino. bathymetric map. tab. 2 litorale di lucrino. principali caratteristiche del moto ondoso. modello previsionale smb (c.e.r.c., 1984), dati di vento rilevati alla stazione di ponza nel periodo 1951-1981. the shore of lucrino. main featur of wave climate (smb method, wind data recorded at the ponza st. during the 1951-1981 period). fig. 13 distribuzione areale delle mode dei sedimenti della spiaggia sommersa di lucrino. the lucrino submarine beach: spatial distribution of the modes of the sediments. sarebbe continuata fino al x secolo d.c. superando i 1718 m dei quali solo 6-7 sono stati recuperati in seguito alle successive fasi ascensionali (russo et al., 1994). dopo un periodo di stasi, sarebbe seguito, dall’ xi fino al xvi secolo, un innalzamento culminato con l’eruzione del monte nuovo nel 1538 la quale dovette apportare profonde modifiche alla morfologia della costa il cui bordo era costituito verosimilmente dalla falesia de “la starza” (fig. 14). il lucrino a quel tempo non era un lago, mentre il lago d’averno era aperto verso il mare da cui era limitato mediante una imponente diga foranea. a partire dal xvii secolo si è assistito ad un lento abbas217lineamenti morfodinamici e sedimentari ... fig. 14 configurazione della costa flegrea in epoca romana con il portus iulius e la linea di riva (ripa puteolana). (da s.t.r. 1993, modificata). the coastal morphology of the gulf of pozzuoli during the roman age. fig. 15 ruderi sommersi dell’antico porto romano di età augustea (portus iulius) nell’area prospiciente il litorale di lucrino (foto cocco, 1987). submerged ruins of the “portus iulius”, the harbour of the ancient roman imperial navy, in front of the lucrino shore. samento del suolo fino alle crisi bradisismiche del 19701972 e 1982-1984, caratterizzate da rapidi e vistosi sollevamenti fino ad un massimo di 330 cm in corrispondenza della falesia di rione terra, su cui sorge il centro storico di pozzuoli (di vito et al., 1987). proprio la dinamica delle due ultime crisi fa supporre, anche sulla base delle documentazioni storiche, che la sommersione di epoca medioevale sia imputabile ad un rapido sprofondamento piuttosto che ad un lento e secolare abbassamento (di vito & luongo, 1993). queste ultime crisi non hanno comportato variazioni planimetriche delle spiagge poste ai limiti occidentale ed orientale del golfo, come è testimoniato dal confronto delle numerose carte topografiche e levate aeree a disposizione per il periodo 1981-1998 (in particolare il confronto 1981-1986 indica una sorprendente stabilità della linea di riva in special modo nell'area delle stufe di nerone, fig. 16) e come è confermato dai dati dell’osservatorio vesuviano nell’ambito della sorveglianza delle aree vulcaniche napoletane. le misure distanziometriche effettuate nell’area nel periodo 19831995 (osservatorio vesuviano, 1995) hanno mostrato una contrazione delle linee misurate (13 cm nel periodo novembre ’91 – giugno ‘95) coerenti con la fase di deflessione della caldera. un'ulteriore conferma è data dal fatto che l’area interessata dal sollevamento presenta una forma circolare con raggio di circa 6 km con centro nella zona del porto di pozzuoli dove gli spostamenti verticali raggiungono la massima entità di sollevamento (330 cm), mentre vanno via via decrescendo fino ad un minimo di 40÷20 cm procedendo verso w e verso e proprio in corrispondenza rispettivamente con le spiagge di lucrino e di bagnoli-coroglio. 22..33..22 llaa ccaarrttooggrraaffiiaa ssttoorriiccaa le prime carte topografiche dei campi flegrei risalgono al xvi secolo e sono opera di incisori fiamminghi. esse sono sostanzialmente riconducibili a due filoni: il primo, derivato dalle incisioni del pittore g. hoefnagel, rientra nel genere del paesaggio pittorico, con poche indicazioni di siti specifici; il secondo, che risale all’olandese n. van aelst, è costituito da vere e proprie carte topografiche, intese come rappresentazione dettagliata del territorio, benché resa in maniera figurativa. al modello di carte di van aelst si rifecero tutti i cartografi successivi, a cominciare da cartaro nella redazione del suo ager puteolanus del 1584, molto interessante per la rappresentazione che vi si fa di molti edifici antichi, nonché di vie di comunicazioni interne. nella seconda metà del xviii secolo, sotto la spinta di nuovi interessi scientifici, quali la vulcanologia e la geologia, la rappresentazione cartografica cominciò a diventare sempre meno figurativa e più tecnica. risale a questo periodo, precisamente al 1782, la “carte du golfe de pouzzoles avec une partie des champs phlégréens dans la terre de labour”, disegnata da un ingegnere militare del regno borbonico, pietro la vega, e inclusa nel “voyage pittoresque” di saintnon. in questa carta topografica si ritrova una particolare attenzione per le testimonianze archeologiche accompagnata da una grande precisione nella rappresentazione dell’orografia. sempre nella seconda metà del xviii secolo, con l’istituzione dell’officina topografica di g. a. rizzi zannoni, nacque una vera e propria scuola di incisione topografica e cominciò una produzione cartografica sistematica che culminerà con la pubblicazione degli atlanti terrestre e marittimo e di varie carte a grande scala dell’area napoletana. tra queste è da segnalare la carta dell’agro napoletano, alla scala 1:50.000, risalente al 1793 e la “carta topografica ed idrografica dei contorni di napoli” alla scala 1:25.000 risalente al 18181819, mostrante con grandissima ricchezza di dettaglio tutte le particolarità del territorio (valerio, 1983). tale carta costituirà, per oltre mezzo secolo, l’unico riferimento attendibile, non solo dell’area flegrea, ma di tutta l’area napoletana (laureti, 1983), tanto da venire ulteriormente aggiornata, nel 1872, da parte dell’istituto topografico militare italiano, sorto, dopo la proclamazione del regno d’italia, dalla fusione degli uffici topografici dei vari stati della penisola. 22..33..33 llee mmooddiiffiiccaazziioonnii aannttrrooppiicchhee fino al 1880 i campi flegrei erano ancora incontaminati, immersi nel verde e circondati da un mare ancora pescoso e cristallino (giamminelli, 1987). oltre alla pesca, il termalismo, con le annesse attività ricreative ed alberghiere, era una delle fonti primarie dell’economia flegrea, tant’è che fu ideato da lamont young (alisio, 1984) un grandioso progetto che prevedeva l’utilizzazione dell’arenile per la balneazione, la costruzione di grandi alberghi, di palazzi per esposizioni e, ovviamente, di abitazioni disposte in maniera molto elegante e separate, di tanto in tanto, da canali alimentati dal mare. questo progetto non fu mai realizzato, anzi, l’economia puteolana fu parzialmente trasformata, nel 1886, dall’istallazione dello stabilimento metallurgico 218 e. cocco et alii fig. 16 litorale di lucrino. variazioni della linea di riva nel periodo 1981-1986 (dalla cartografia del comune di pozzuoli in scala 1:4.000). the shore of lucrino. shoreline changes during the 1981-1986 period. armstrong che occupò quasi completamente il litorale tra pozzuoli ed arco felice, dando così inizio al progressivo degrado ambientale ed all’alterazione del paesaggio costiero che nei decenni successivi, con il procedere dell’industrializzazione (ad es. ilva di bagnoli), interessarono tutto il golfo. negli ultimi 50 anni si evidenzia la progressiva e totale antropizzazione della fascia costiera: lungo il tratto occidentale del golfo (stufe di nerone porto di pozzuoli) la linea di riva si presenta frazionata in tante curve spezzate, limitate da opere di difesa trasversali; il settore centrale risulta caratterizzato dalla presenza, quasi ininterrotta, di barriere emerse, talché il lungomare di pozzuoli (figg. 17 a e b) e la strada litoranea verso bagnoli risultano separate dal mare a mezzo di una continua scogliera aderente e di ripetute colmate in cemento; la fascia orientale (la pietra coroglio) presenta lunghi pontili ed ampie piattaforme artificiali, legati agli stabilimenti industriali (figg. 17 c e d). 33.. ccoonncclluussiioonnii le ricerche condotte lungo la fascia costiera dei campi flegrei hanno messo in evidenza tre tratti a caratteri ed evoluzione differenziati. 1) il litorale di cuma, con l’assetto tipico di una costa sabbiosa deposita limitata verso l’interno da cordoni dunari più o meno antropizzati, alimentata dal materiale terrigeno proveniente dal f. volturno, attraverso le correnti di lungo costa. il settore risulta molto esposto alle ondazioni provenienti da w-nw. 2) il litorale di miliscola, caratterizzato da una marcata crisi erosiva negli anni ’70 cui si è cercato di porre rimedio attraverso la realizzazione di numerose opere di difesa che hanno stabilizzato solo parzialmente il settore inducendo una tendenza all’arretramento nell’area di sottoflutto. 3) il golfo di pozzuoli, caratterizzato da profonde modifiche naturali fin dall’epoca storica (bradisismo, eruzione di monte nuovo) e da una antropizzazione crescente a partire dalla fine del xix secolo ad oggi (le spiagge naturali oggi sono praticamente assenti). le ultime crisi bradisismiche degli anni ’70 e ‘80 hanno provocato una evidente emersione (oltre 300 cm) della falesia di rione terra su cui sorge il centro storico di pozzuoli, ma non hanno comportato variazioni planimetriche apprezzabili delle spiagge poste ai limiti occidentale (lucrino) ed orientale (bagnoli) del golfo dove i sollevamenti sono stati dell’ordine di pochi decimetri. rriinnggrraazziiaammeennttii si ringrazia l’ing. m. serpico per il contributo relativo alla definizione delle caratteristiche principali del moto ondoso. la stampa del presente articolo è stata supportata da fondi di ricerca individuali. 219lineamenti morfodinamici e sedimentari ... fig. 17 antropizzazione della fascia costiera. a e b: come si presentava il lungomare di via napoli (pozzuoli) negli anni ‘50 e nel 1998. c e d: il litorale di bagnoli agli inizi del ‘900 e nel 1998. human activities along the coast of pozzuoli (during the ‘50 -a and 1998 -b) and bagnoli (in the beginning of 1900 –c and in 1998 –d). 220 ms. ricevuto il 19 febbraio 2002 testo definitivo ricevuto il 24 settembre 2002 ms. received: february 19, 2002 final text received: september 24, 2002 llaavvoorrii cciittaattii alisio g. 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(1990) i greci in campania. in “ i campi flegrei un itinerario archeologico” (a cura di amalfitano p., camodeca g., medri m.). marsilio editori, napoli, 7-10. vecchi l., morhange c., blanc p.-f., goiran j.-p., buï thi mai, bourcier m., carbonel p., demant a., gasse f., girard m. & verrecchia e. (2000) la mobilité des milieux littoraux de cumes, champs phlégréens, campanie, italie du sud. méditerranée n° 1-2, 71-82. imp.soligo nneeww uu--sseerriieess ddaattiinngg ooff aa ccaarrbboonnaattee lleevveell uunnddeerrllyyiinngg tthhee ppeeppeerriinnoo aallbbaannoo pphhrreeaattoommaaggmmaattiicc iiggnniimmbbrriittee ((ccoollllii aallbbaannii,, iittaallyy)) mmiicchheellee ssoolliiggoo,, ppaaoollaa ttuucccciimmeeii,, gguuiiddoo ggiioorrddaannoo,, rreennaattoo ffuunniicciieelllloo && ddoonnaatteellllaa ddee rriittaa dipartimento scienze geologiche, università "roma tre", largo s.l. murialdo 1, 00146 roma , italy. correspondence should be addresses to paola tuccimei: tuccimei@uniroma3.it abstract increasing attention has been recently devoted to the last phases of the colli albani activity (rome, italy), in consideration of new stratigraphic data suggesting a possible holocene activity of the volcanic complex located few kilometres to the south of the city of rome. in particular the focus has been directed to the activity of the albano maar and related pyroclastic deposits, the youngest eruptive centre of the colli albani volcano. the most recent dated product from the albano maar is known as peperino albano (pa) ignimbrite, which has been dated with several different techniques. the age of the pa spans between 51 and 19 ka. a recent study has shown that pa is overlain by at least other two pyroclastic deposits and several lahar deposits, all separated by paleosoils, making the recent eruptive history of the albano maar rather younger than previously thought. the exact age determination of the recent succession is therefore a key issue to be tackled in order to evaluate the volcanic hazard in the roman region. the aim of this paper is to improve the chronology of the last eruptive episodes of the albano maar, by dating a carbonate layer interbedded within the recent deposits using u-series disequilibria. the idea came out from the discordant results obtained by applying different dating methods to pa ignimbrite as a consequence of the difficulties connected with the application of classical isotope chronological methods to young volcanic products. in order to date the carbonate layer, the total sample dissolution technique (tsd) has been preferred to using leachates alone because the leaching method gives reliable results only in the case of simple dissolution of the carbonate fraction, without any removal of u and th isotopes from the detritic component. three coeval sub-samples from the carbonate level underlying pa have been analysed, giving an age of 22.9 ± 6.7 ka, younger than other previous chronological data. the age limit of about 23 ka found for pa supports the hypothesis of a possible very recent activity of the albano maar, justifing the increasing efforts devoted to improving the chronology of the last phreatomagmatic phases of colli albani volcano. riassunto una crescente attenzione è stata recentemente dedicata alle ultime fasi dell'attività dei colli albani (roma, italia), in considerazione di nuovi dati stratigrafici che suggerirebbero una possibile attività olocenica del complesso vulcanico situato pochi chilometri a sud della città di roma. in particolare, l'attenzione è stata focalizzata sul più recente centro eruttivo dei colli albani (maar di albano) e sui depositi piroclastici ad esso associati. il più recente tra i prodotti datati del maar di albano è un'ignimbrite conosciuta come peperino di albano (pa). tale unità è stata datata con differenti tecniche e le età ottenute sono comprese tra 51000 e 19000 anni. un recente studio mostra come pa sia ricoperto da almeno altri due depositi piroclastici e ulteriori due lahar, tutti separati da paleosuoli, dimostrando che la recente storia eruttiva del maar di albano sia più giovane di quanto sinora ritenuto. l'esatta determinazione dell'età di questa successione risulta pertanto un obbiettivochiave nella valutazione del rischio vulcanico nell'area romana. lo scopo di questo lavoro è fornire un approccio alternativo per migliorare la cronologia degli ultimi episodi eruttivi del maar di albano, attraverso la datazione col metodo dei disequilibri nella serie dell'uranio di un livello carbonatico intercalato ai prodotti del maar sopramenzionato. l'idea è scaturita dai risultati discordanti ottenuti applicando differenti metodi di datazione al peperino di albano, riconducibili alle difficoltà spesso connesse alla datazione diretta di prodotti vulcanici recenti. al fine di datare il livello carbonatico, la tecnica della dissoluzione totale del campione (tsd) è stata preferita all'uso dei soli lisciviati poiché l'analisi di questi ultimi fornisce risultati attendibili solo in caso di una semplice dissoluzione della frazione carbonatica, senza la rimozione preferenziale di u e th dalla componente detritica. sono stati analizzati tre subcampioni coevi appartenenti al livello carbonatico sottostante il peperino di albano e l'età risultante è pari a 22900 ± 6700 anni. questo dato è il più recente tra quelli sinora ottenuti e corrobora l'ipotesi di una possibile recentissima attività del maar di albano, giustificando il crescente impegno speso nel migliorare la cronologia delle ultime fasi freatomagmatiche del vulcano dei colli albani. keywords: u-series dating, peperino, ignimbrite, colli albani, italy parole chiave: datazioni, serie dell'uranio, peperino, ignimbrite, colli albani, italia il quaternario italian journal of quaternary sciences 1166(1bis), 2003, 115-120 11.. iinnttrroodduuccttiioonn the first attempt to date colli albani volcanic complex date back to about 35 years ago when evernden and curtis (1965) dated leucite crystals by k/ar obtaining ages ranging from 706 to 268 ka. during the 1960's and 1970's the k/ar method was further developed (gasparini & adams, 1969; masi et al., 1976; biddittu et al., 1979 bernardi et al., 1982) giving results comparable with the previous data. in the same years other radiometric methods based on u-series disequilibria (th/u isochrons and fission tracks) were used (cerrai et al., 1965; taddeucci, 1969; bigazzi & ferrara, 1971) supporting the occurrence of recent volcanic activity in the interval 67-43 ka. in the 1980's and 1990's, 39ar/40ar method was associated to k/ar and th/u systematics (e.g. karner and renne, 1998). the application of the three methods to the main volcanic units permitted the 116 m. soligo et al. improvement of the chronological knowledge of the complex (radicati di brozolo et al., 1981; andretta & voltaggio, 1988). notwithstanding the numerous papers dedicated to define the chronology of colli albani activity, various problems related to the different methods arose. the first, connected with the application of k/ar method, was suggested by villa (1988) who envisaged the presence of excess argon in the analysed materials. further difficulties arose from the direct comparison of 39ar/40ar and th/u methods applied to the same products. villa (1992) and voltaggio et al. (1994) found in three samples out of four systematically 39ar/40ar ages older than those obtained by th/u, presumably due to excess argon in microscopic inclusions in leucite crystals. according to villa (1988) the presence of excess 40ar can be identified from an accurate examination of the spectra, but if the excess 40ar is uniformly distributed (voltaggio et al., 1994) there is no way of distinguishing between radiogenic and inherited argon. also the th/u isochron method can be affected by problems, the main of which being related to the initial isotopic heterogeneity of the thorium activity ratio. this paper focuses on the age determination using the u-series disequilibria of a carbonate level found at the base of the peperino albano (pa) ignimbrite, one of the most recent products from the colli albani volcano, erupted from the albano maar. the age determination should be independent from the above mentioned uncertainty factors, and its importance is therefore twofold: 1) it helps at determining the controversial age of the peperino albano ignimbrite, which has been dated using 14c, u/th disequilibrium and thermoluminescence techniques (fornaseri and cortesi, 1989 and references therein; mercier, 1993), with reliable ages spanning between 51,000 years ago and 19,000 years ago and clustering around 29-30 ka (fornaseri and cortesi, 1989). 2) it constrains the recent activity of the colli albani volcano which is much more complex and recent than usually believed, as the carbonate layer has been found at the base of a newly exposed stratigraphic section, where the peperino albano is overlain by several other phreatomagmatic and lahar units (funiciello et al., 2002) 22.. ggeeoollooggiiccaall sseettttiinngg the colli albani volcano is a large composite caldera complex located about 20 km south-east of the city of rome (fig.1). it is one of the several volcanoes belonging to the nw-trending volcanic belt parallel to the tyrrhenian coast of central italy active during the last 600 ka, belonging to the roman magmatic province (e.g. serri, 1990; ferrara and manetti, 1993). the colli albani volcano is at present considered a quiescent volcano (de rita et al., 1995a) characterised by seismic and hydrothermal activity (amato and chiarabba, 1995; calcara et al., 1995). the style of activity of the colli albani volcano has been characterised mainly by explosive activity throughout its volcanic history. the stratigraphy has been subdivided in three main successions corresponding to three epochs of activity. the lowest, named the tuscolano-artemisio succession, was emplaced between less than 600 ka and 350 ka and comprises seven main large-volume, caldera-forming, low aspect ratio ignimbrite units. the tuscolano-artemisio succession comprises the most voluminous and widespread deposits of the colli albani volcano (fig. 1) (de rita et al. 1995b). the last large-volume ignimbrite-forming eruption caused the final collapse of the central 10 km x 10 km wide caldera at 350 ka (de rita et al. 1988; de rita et al., 1995b). after the collapse, the volcanic activity changed drastically into strombolian and effusive accompanied by a significant reduction of the average mass eruption rate. during this epoch of activity, named le faete epoch which lasted approximately from 350 ka and 270 ka, a small stratovolcano named le faete edifice was formed within the collapsed area (de rita et al., 1995b). the most recent volcanic activity of the colli albani volcano, the final epoch of activity, has been characterised by several, small volume, monogenetic phreatomagmatic eruptions from eccentric maars, whose products form the final hydromagmatic succession (de rita et al., 1995b). phreatomagmatic eruptions occurred from single and coalescent craters. the albano maar is the most recent of these craters, wherefrom the peperino albano ignimbrite erupted (de rita et al., 1986; giordano et al., 2002). different attempts have been carried out to date the peperino albano. a first was conducted on unburned ulmus and quercus ilex wood samples giving a 14c roma maar albano 0 5 10km 41°55° 41°50° 41°45° 41°40° 41°35°n 12°27°e litosoma albano 260 ka recente; ca. 1km3 di prodotti) formazione del tavolato (<23.000-<5000 anni) formazione del tavolato (<23.000-<5000 anni) alluvioni e depositi costieri recenti orlo di caldera cono di scorie orlo di maar samling site unità sedimentarie pre-vulcaniche litosoma tuscolano-artemisio (600 350 ka; ca. 280 km3 di prodotti) piroclastiti lave prodotti freatomagmatici litosoma delle faete (350 270 ka; ca. 6 km3 di prodotti) 12°50° 12°57° fig. 1 geological map of alban hills area (rome, italy). upper age of 29.7 ± 0.4 ka (de vries, in fornaseri et al., 1963). further radiocarbon determinations were performed on similar samples and the obtained ages were higher than 37 ka (alessio et al., 1966; fornaseri, 1985). more recently fornaseri and cortesi (1989) reported a radiocarbon age of 29.9 ± 0.3 ka. this range is in agreement with ar/ar age determination from sediment-cores ascribed to pa eruption and drilled at the centre of the lake (chondrogianni et al., 1996). also villa et al. (1999) dated unalterated leucite crystals from other sedimentcores by ar/ar. they found that the evolution of the crater was a multistage process that took place in the last 45 ka. two stages out of five (the first and the third), were dated at of 45 ± 3 and 26 ± 1 ka, respectively. in addition, a th/u isochron was realized using different mineral phases from the peperino albano (andretta, 1988) with the resulting age of 51 ± 14 ka. mercier (1993) used the thermoluminescence technique to date calcareous inclusions within pa obtaining an age of about 20 ka. finally the recovering of uran-pyrochlore in sanidine ejecta of the iv hydromagmatic units from the albano maar has allowed to date the age of crystallization of these mineral phases by the u/th method at 45 ± 1.3 ka (voltaggio and barbieri, 1995). 33.. ssttrraattiiggrraapphhyy figure 2 shows the stratigraphic section investigated in this study. this section was recently exposed thanks to roadworks related to the enlargement of the gra freeway, in the ciampino area, located along the nw slope of the colli albani volcano. the detailed stratigraphy of this section is reported in funiciello et alii, in press, to which the reader is referred to. the succession has been interpreted by the authors as the post-wurmian, possibly up to the holocene filling of a paleovalley cut in the underlying tuscolano-artemisio epoch’s deposits. the succession from base to top is composed by: a) fluvial lacustrine silt and sand b) phreatomagmatic surge deposit related to the iv eruption from the albano maar c) fluvial sand and conglomerate d) peperino albano ignimbrite e) syn-eruptive reworked deposits from the peperino albano ignimbrite f) phreatomagmatic surge deposit g) debris flow lahar deposit f) hyperconcentrated flow lahar deposit the carbonate level (fig. 3) was deposited at the top of unit a, which is composed of diffusely stratified silt and clay, likely from a caco3-rich swamp, similar to the 117new u-series dating of a carbonate ... many swamps that occur in several places around the colli albani area, where co2 rich fluids upwell to the surface. it must be underlined that the ciampino area is still the site of intense co2 release (e.g. giordano et al., 2000; carapezza et al., 2002) 44.. ssaammpplliinngg aanndd mmeetthhoodd 44..11 tthheeoorreettiiccaall ccoonnssiiddeerraattiioonnss three coeval sub-samples from the carbonate level underlying the last erupted products from albano maar were collected and analysed by u-series method, according to the total-sample dissolution (tsd) technique developed by bischoff and fitzpatrick (1991) for dating impure carbonates. the choice of such a method has been preferred to using leachates alone (schwarcz and latham, 1989) because the leaching method gives reliable results only in the case of selective dissolution of the carbonate fraction, without any removal of u and th isotopes from the detritic component, or when u and th are leached without any fractionation. generally this condition is not verified because u and th are often fractionated and th can be readsorbed onto the residual component. when analysing samples consisting of simple mixtures of carbonate and a detritic component, the phreatomagmatic surge fig. 2 stratigraphic section of grande raccordo anulare (gra) succession: a) fluvial lacustrine silt and sand, b) phreatomagmatic surge, c) fluvial sand and conglomerate, d) peperino albano, e) lahars, f) phreatomagmatic surge, g) debris flow, h) hyperconcentrated flow. 118 use of tsd method is to be preferred to determine the age because the sample is totally dissolved and consequently no preferential leaching or readsorption occur. in order to successfully apply this method it is required that the various coeval subsamples have different u/th ratios, but the same (230th/232th) activity ratio when deposited. tsd method assumes that: 1) the detritic component is homogenous and characterised by a constant u/th ratio or 2) it is a heterogeneous mixture of two or more minerals with different u/th ratio, but similar (230th/232th). in both cases the resulting age is that of formation of the carbonate. the age of the carbonate level was calculated measuring the (230th/232th), (234u/232th) and (238u/232th) activity ratios of several coeval subsamples in order to obtain the value of (230th/234u) and (234u/238u) activity ratios in the pure carbonate fraction. such values are respectively calculated from the slopes of the regression lines in the ( 230th/ 232th) vs ( 234u/ 232th) and ( 234u/ 232th) vs (238u/232th) isochron plots reported in figure 4a and 4b. calculations have been carried out using isoplot, a plotting and regression program for radiogenic-isotope data (ludwig, 1994). 44..22 aannaallyyttiiccaall tteecchhnniiqquuee samples were crushed and ultrasonically washed in deionised water. fragments were also checked with a stereoscopic microscope to discard any recrystallised portions. about 10 g of sample were dissolved with 7 n hno3. the insoluble residue was removed by centrifugation and successively digested in concentrated hf + hclo4 + hno3, taken to dryness and redissolved in 7 n hno3. the resulting solution was mixed with the carbonate solution and spiked with a tracer containing 228th in secular equilibrium with 232u. u and th were coprecipitated with fe(oh) 3 using nh4oh and successively redissolved in 10 n hcl and loaded onto anionic dowex ag1-x8 resin to separate th from u. thorium fraction was furthermore purified onto a second anionic dowex ag1x8 resin conditioned with 7 n hno3 and eluted with 10 n hcl. u and th isotopic complexes were extracted from nitric solutions respectively at ph 3.5 and 1.5 using thenoyltrifluoroacetone (tta) in toluene and loaded onto a glass planchet and flamed. u and th were finally alpha-counted using high resolution ion implanted ortec silicon surface barrier detectors. 55.. rreessuullttss uranium and thorium concentration, activity ratios and ages are summarised in table i. quoted uncertainties are 1 standard deviation (± 1 sigma). resulting isochrons are shown in fig. 4a and 4b. data points are finely distributed on the ( 230th/ 232th) vs ( 234u/ 232th) and ( 234u/ 232th) vs (238u/232th) isochron plots and arranged in two straight lines whose correlation coefficients r are higher than 0.96. the obtained age is equal to 22.9 ± 6.7 ka. m. soligo et al. fig.3 view of the dated carbonatic level in layer a (fluvial lacustrine sand and silt), close to the limit with the overlying level b (phreatomagmatic surge), as in figure 2. fig 4b (234u/232th) versus (238u/232th) isochron plot of the three carbonate sub-samples from gra section. fig. 4a (230th/232th) versus (234u/232th) isochron plot of the three carbonate sub-samples from gra section. uranium abundances of different subsamples range from 4 to 4.6 ppm, thorium contents vary from 4.7 to 9.6 ppm and (234u/238u) activity ratio in the pure carbonate fraction is around 1. such data demonstrate that 119 carbonate depositing fluids have circulated within a volcanic bedrock usually characterised by high uranium content and (234u/238u) activity ratios close to equilibrium. in addition, the high obtained thorium concentrations are consistent with a volcanic nature of the insoluble residue. 66.. ddiissccuussssiioonn aanndd ccoonncclluussiioonn the peperino albano ignimbrite erupted from the albano maar has been dated several times by the application of different methods. resulting ages differ significantly from each other and range between 51 and 19 ka. as mentioned before, data from the direct analyses of crystals of pa are affected by various problems of isotope disequilibria, but also 14c determinations on carbon-rich samples in volcanic areas (leaves, branches etc.), where intense co2 emissions occur, can be unreliable (calderoni and turi, 1998). actually, the carbon isotopic composition of organism living close to sites of intense co2 release in air can be presumably depleted in radiogenic carbon and consequently the obtained ages are not correct and result too old. in light of this, it is necessary to produce an independent dating of pa in order to better constrain the chronology of last products from albano maar. this aim has been reached with the determination of the age of the carbonate level outcropping in the gra stratigraphic section and underlying pa. the u-series method using tsd (total sample dissolution) technique is to be preferred when analysing an impure carbonate with a relevant detritic component because it allows the overcoming of problems connected with the differential leaching and adsorption of u and th isotopes from the insoluble residue. in view of this, the obtained results can be considered reliable. the age of 22.9 ± 6.7 ka determined for the carbonate level indicate a very recent eruptive history of the albano maar, rather younger than previously thought. this finding assumes a significant value especially in consideration of the recently described pyroclastic and lahar deposits overlying pa ignimbrite (see fig. 2). it is worth noting that such products are also separated by paleosoils indicating that a considerable span of time has to have been elapsed since the emplacement of the pa. this points to a possible holocene age of the products filling the paleovalley cut into the tuscolanoartemisio volcanic succession to the nw of the albano maar. such considerations also allow the re-evaluation of datings from andretta & voltaggio (1988) who proposed a very recent activity of the colli albani complex, although that work did not clarified which stratigraphic layers were dated. in conclusion, the recent activity of the albano maar, needs more study in order to better define the volcanic hazard in the colli albani region because of the proximity of this area to a large city like rome. rreeffeerreenncceess alessio a., bella f., calderoni g., bachechi f., cortesi c., l., 1966 university of rome 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"the vulcano of the alban hills. tip. sgs roma, 167-192. m. soligo et al. impaginato giraudi llee oosscciillllaazziioonnii ddeell gghhiiaacccciiaaiioo ddeell ccaallddeerroonnee ((ggrraann ssaassssoo dd''iittaalliiaa,, aabbrruuzzzzoo - iittaalliiaa cceennttrraallee)) ee llee vvaarriiaazziioonnii cclliimmaattiicchhee ddeeggllii uullttiimmii 33000000 aannnnii ccaarrlloo ggiirraauuddii enea c.r. casaccia, c.p. 2400, 00100 roma a.d. riassunto i detriti di origine glaciale conservati appena a valle della soglia del circo del ghiacciaio del calderone, sono stati inquadrati dal punto di vista cronologico grazie alla datazione di suoli ad essi intercalati e sovrapposti. le date indicano quattro espansioni glaciali: la prima successiva a 2650±60 anni radiocarbonio bp, la seconda compresa tra 1450±40 e 670±40 anni bp, la terza successiva a 670±40 anni bp, l'ultima databile al xix secolo. le espansioni del ghiacciaio del calderone possono essere correlate con fasi di avanzata dei ghiacciai alpini. per cercare di individuare con maggiore precisione i periodi favorevoli all'espansione glaciale e per ridurre, quindi, l'incertezza delle datazioni, si é fatto ricorso all'esame delle variazioni di livello dei laghi fucino e trasimeno; questi, in base alla letteratura, aumentavano di livello in sintonia con le fasi di avanzata glaciale. dal confronto si deduce che la prima espansione glaciale (calderone 2) sarebbe databile al periodo compreso tra vii e ii÷iii secolo bc, la seconda (calderone 3a) sarebbe databile ad un periodo compreso tra i secoli vii e x ad, la terza (calderone 3b) sarebbe databile tra il xvi e parte del xix secolo ad, l'ultima (calderone 3c) dovrebbe risalire al xix secolo ad. di conseguenza dovettero verificarsi fasi di riscaldamento climatico che produssero contrazioni dei ghiacciai tra il iii÷ii secolo bc ed il vi secolo ad, tra il x e il xiii secolo ad ed alla fine del xix secolo ad. in base alle differenze di limite nivale, la temperatura media annuale nel corso delle fasi di massima avanzata glaciale doveva essere inferiore all'attuale di almeno 1,1° ÷ 0,8°c. abstract the variations of the calderone glacier (gran sasso d'italia, abruzzo, central italy) and the climatic oscillations during the last 3000 years. the age of the debris of glacial origin, lying just downvalley of the threshold of the cirque of the calderone glacier, has been obtained dating interbedded soils by means of radiocarbon analysis. the datings point out four glacial expansions: the first, following 2650±60 years bp, the second bracketed between 1450±40 and 670±40 years bp, the third following 670±40 years bp, the last datable to the xix century. the expansions of the calderone glacier can be correlated to the advances of the alpine glaciers. in order to try to date with greater precision the periods favourable to expandig glacier and to reduce the uncertainty of the datings, the variations of the fucino and trasimeno lakes have been considered; these lakes, according to previous works, increased in level during the glacial advances. the comparison between lake and glacial data indicates that the first glacial advance (stage calderone 2) occurred during the period between the vii and the ii÷iii century bc, the second (stage calderone 3a) between the vii and x century ad, the third (stage calderone 3b) between the xvi and part of the xix century ad, the last (stage calderone 3c) during the xix century ad. as a consequence, one can assume that some climatic warmings took place producing glacial retreat between iii÷ii bc and vii century ad, x and xiii century ad, and at the end of the xix century ad. based on the differences in the equilibrium line altitude, the mean yearly temperature during the periods of maximum glacial advance must have been lower than the present one of, at least, 1,1° ÷ 0,8°c. parole chiave: gran sasso, ghiacciaio del calderone, variazioni glaciali, clima olocene, piccola età glaciale. keywords: gran sasso massif, calderone glacier, glacial oscillations, holocene climate, little ice age. il quaternario italian journal of quaternary sciences 1155(2), 2002, 149-154 iinnttrroodduuzziioonnee sul massiccio del gran sasso (2912 m), posto a circa 42°30' n nell'appennino centrale, è presente il ghiacciaio del calderone, il più meridionale d'europa. il ghiacciaio è per lo più un "debris covered glacier" che raggiunge lo spessore massimo di circa 15 m (gellatly et al., 1992; smiraglia & veggetti, 1992; d'orefice et al., 1996; fiucci et al., 1997). tale ghiacciaio è in forte riduzione a partire dagli anni '60, dopo una fase di regresso più contenuta che durava almeno dall'inizio del '900 (marinelli & ricci, 1916; tonini, 1961; smiraglia & veggetti, 1991; gellatly et al., 1992, 1994). il ghiacciaio sopravvive al di sotto del limite delle nevi teorico calcolato da tonini (1961) a causa delle condizioni locali, essendo conservato in un circo rivolto a ne tra ripide pareti dirupate. vari autori (federici,1979; gellatly et al., 1992,1994; jaurand,1994) hanno avanzato ipotesi sull'età di alcune forme e depositi glaciali presenti a valle o sulla soglia del circo del calderone, ma solo recentemente (giraudi, 2000) sono state utilizzate datazioni radiometriche per inquadrare le fasi di espansione, dimostrando che il ghiacciaio del calderone, scomparve nelle fasi più calde dell'olocene, e si riformò (stadio calderone 1) in un periodo successivo a 3895±65 anni bp, quando il limite nivale (ln) raggiunse circa 2750 m. in seguito il ghiacciaio fu soggetto ad altre fasi di espansione: la prima (stadio calderone 2, con ln 2750÷2770 150 c. giraudi m) successiva a 2650±60 anni bp (data calibrata 2 sigma 905÷775 bc), la seconda, più complessa, (stadio calderone 3a, b, c), attribuita alla piccola età glaciale, con ln inferiore o uguale a 2730 m. scopo del presente lavoro é quello di datare le morene degli stadi calderone 2, 3a,b,c, vale a dire i depositi prodotti dalle espansioni glaciali degli ultimi 3000 anni, al fine di determinare se vi sono correlazioni tra le avanzate glaciali appenniniche ed alpine e di valutare le oscillazioni climatiche che le hanno prodotte. mmeettooddii il metodo di lavoro adottato nella presente ricerca è basato sulla datazione di suoli intercalati o sovrapposti ai detriti glaciali conservati a poche centinaia di metri dalla soglia del circo glaciale. il circo che ospita il ghiacciaio del calderone è sospeso alla testata della valle delle cornacchie; poco oltre la sua soglia la valle assume pendenze molto elevate, passando dal 17%, al 60-÷70% in media, ma con tratti caratterizzati da gradini sub-verticali. come discusso in un altro lavoro (giraudi, 2000), quando la lingua glaciale superava la soglia del circo, il ghiaccio precipitava a valle, così come il detrito glaciale. in corrispondenza di tratti del fondovalle leggermente meno inclinati si formavano quindi falde di detrito discontinue (2, 4 e 5 in fig. 1), la geometria delle quali indica chiaramente la zona di alimentazione e quindi l'apparato morenico di provenienza. questa situazione appare partifig. 1 carta geologica schematica dei depositi glaciali e dei detriti studiati presenti nell'area sommitale del corno grande, massiccio del gran sasso. legenda: 1detrito di versante; 2detrito glaciale dello stadio calderone 3b; 3morene degli stadi calderone 3b,c; 4morene e detrito glaciale dello stadio calderone 3a; 5morene e detrito glaciale dello stadio calderone 2; 6morene dello stadio calderone 1; 7morene dello stadio franchetti; 8morene dello stadio cornacchie; 9circo del calderone; 10cordone morenico; 11nivomorena. geological sketch map of the studied glacial and slope waste deposits near the calderone glacier (corno grande-gran sasso massif). legend: slope waste deposits; 2stage calderone 3b glacial debris; 3stage calderone 3b,c moraines; 4stage calderone 3a moraine and apron of fallen glacial debris; 5stage calderone 2 moraine and apron of fallen glacial debris; 6stage calderone 1 moraines; 7stage franchetti moraine; 8stage cornacchie moraine; 9cirque of the calderone glacier; 10moraine ridge; 11protalus rampart. colarmente evidente per lo stadio calderone 3a,b, ma è riconoscibile anche per lo stadio calderone 2, le cui morene frontali sono conservate sulla soglia del circo glaciale. rilevando la distribuzione dei detriti collegati ai vari apparati morenici frontali, ricostruendo i loro rapporti stratigrafici e campionando suoli sepolti o sovrapposti ai detriti, é stato possibile ottenere la datazione delle ultime espansioni del ghiacciaio del calderone. rriissuullttaattii la carta geologica schematica di fig. 1 evidenzia i depositi glaciali e le falde detritiche prese in considerazione nel presente lavoro. il più antico degli accumuli di detrito presi in considerazione (5 in fig. 1) é formato prevalentemente da clasti grossolani eterometrici, con scarsa matrice, e mostra di essere stato alimentato dal fronte delle morene dello stadio calderone 2. il detrito presenta una scarsissima copertura vegetale, ma scavando tra i clasti si possono rinvenire, a luoghi, i resti di un suolo sabbioso-limoso non visibile in superficie. il suolo deve essere stato dilavato quasi totalmente, conservandosi solo in piccoli lembi laddove é stato coperto da detrito messo in posto da processi crio-nivali superficiali. nella zona del rifugio franchetti (circa 400 m dalla soglia del circo, alla quota di circa 2450 m) il detrito glaciale (fig. 2) é interdigitato con detrito derivante da una piccola scarpata adiacente. il detrito di versante, che risulta assai più fine e con abbondante matrice sabbiosa, copre un suolo (giraudi, 2000) datato 2650±50 anni bp col metodo del radiocarbonio (calibrato 2 sigma 905÷775 bc). il secondo accumulo detritico (4 in fig. 1), ancora 151le oscillazioni del ghiacciaio del calderone ... costituito da clasti grossolani eterometrici, ma di dimensioni leggermente minori rispetto al precedente, mostra di essere stato alimentato dalle morene dello stadio calderone 3; si sovrappone al detrito della prima fase (5 in fig. 1) e copre anche una nivomorena. nella zona del rifugio franchetti, il detrito di origine glaciale appare interdigitato con detrito di versante (fig. 2). questo, ben distinguibile dagli altri per la presenza di molta matrice sabbiosa, copre un suolo grigio scuro datato 1450±40 anni bp col metodo del radiocarbonio (data calibrata 2 sigma: ad 540÷660). anche in questo caso, sul detrito glaciale la copertura vegetale é estremamente ridotta ma, scavando tra i clasti, si possono rinvenire i resti, coperti da poco detrito fine, di un suolo limoso grigio scuro ricco di sostanza organica; questo, sottoposto a datazione col metodo del radiocarbonio, ha fornito un'età di 670±40 anni bp (data calibrata 2 sigma: ad 1270÷1400). il suolo deve essere stato dilavato quasi completamente, ma si é conservato in piccoli lembi laddove é stato coperto da detrito mobilizzato da processi crio-nivali superficiali. il terzo accumulo detritico (2 in fig. 1) è il più continuo arealmente, risulta formato da clasti di dimensioni inferiori rispetto ai precedenti, e presenta matrice sabbiosa limosa più abbondante. su tale accumulo la copertura vegetale é praticamente assente: non sono stati rinvenuti suoli o resti di suoli. i clasti di roccia carbonatica hanno aspetto molto fresco ed in alcune zone il detrito appare interessato da piccoli debris flow, legati a fenomeni di instabilità attuale. il detrito é direttamente collegato alla morena dello stadio calderone 3b, e copre quello della seconda fase (4 in fig. 1). vista la situazione stratigrafica, si assume quindi che il secondo deposito detritico sia contemporaneo alla formazione delle morene dello stadio calderone 3a, precedenti a quelle dello stadio calderone 3b. ne emerge un inquadramento cronologico per le fasi di espansione glaciale che può essere così riassunto: la fase di espansione glaciale che ha dato luogo alla formazione delle morene dello stadio calderone 2 è più recente di un suolo datato 2650±50 anni bp e più antico di un suolo datato 1450±40 anni bp; la fase di espansione glaciale che ha prodotto le morene dello stadio calderone 3a è successiva ad un suolo datato 1450±40 anni bp e precedente ad un ulteriore suolo datato 670±40 anni bp; fig. 2 schema dei rapporti stratigrafici tra i detriti di origine glaciale e di versante nella zona del rifugio franchetti. legenda: 1detrito glaciale dello stadio calderone 3a con lembi di suolo conservati al tetto; 2detrito di versante eteropico con il detrito glaciale dello stadio calderone 3a; 3detrito glaciale dello stadio calderone 2 con lembi di suolo conservati al tetto; 4detrito di versante eteropico con il detrito glaciale dello stadio calderone 2; 5detrito di versante; 6suoli sepolti stratigraphyc sketch of the glacial and slope debris near rifugio franchetti. legend: 1stage calderone 3a glacial debris with remnants of a soil at the top; 2slope waste deposits heteropic with stage calderone 3a glacial debris; 3stage calderone 2 glacial debris with remnants of a soil at the top; 4slope waste deposits heteropic with stage calderone 2 glacial debris; 5older slope waste deposit; 6interbedded soils. 152 c. giraudi la fase di espansione nel corso della quale si sono formate le morene dello stadio calderone 3b é successiva al suolo datato 670±40 anni bp; la fase di espansione che ha dato luogo alle morene dello stadio calderone 3c è molto vicina al fronte glaciale documentato per la fine del xix secolo e dovrebbe quindi risalire allo stesso periodo. ddiissccuussssiioonnee l'inquadramento cronologico delle fasi di espansione glaciale é stato ottenuto mediante datazione di suoli coperti da detrito. quando si datano i suoli col metodo del radiocarbonio, la data che si ottiene indica l'età media delle sostanze organiche presenti al momento del seppellimento (matthews, 1993). il seppellimento ad opera di detrito caduto dal fronte glaciale coincide con il superamento, da parte del ghiacciaio, della soglia del circo: le massime estensioni degli stadi calderone 2, 3a e 3b, sono quindi state raggiunte in un momento che può essere anche sensibilmente successivo alle date indicate dai suoli. nonostante l'approssimazione insita nelle date, possiamo correlare la fase di espansione glaciale calderone 3b (successiva a 670±40 anni bp/ cal. 1270÷1400 ad) alla piccola età glaciale. lo stadio calderone 3a appare databile al periodo medioevale (successivo alla copertura del suolo datato 1450±40 bp/ cal.540÷660 ad) e precedente allo sviluppo del suolo datato 670±40 anni bp/ cal. 1270÷1400 ad. lo stadio calderone 2, successivo a 2650±50 anni bp/ cal. 905÷775 bc e precedente a 1450±40 bp/ cal.540÷660 ad, cade nell'età del ferro o nel periodo romano. il confronto tra le date ottenute sul massiccio del gran sasso e quelle conosciute per le espansioni glaciali degli ultimi 3000 anni sulle alpi mostra una buona corrispondenza, anche se alcune date ottenute dai suoli sepolti lasciano una ampia incertezza cronologica. orombelli & pelfini (1985) indica un'avanzata del ghiacciaio dei forni (ortles-cevedale) precedente a depositi torbosi datati 2670±130 bp, che potrebbe coincidere con lo stadio calderone 1 (precedente a quelli trattati nel presente lavoro, segnalato in giraudi, 2000). baroni & carton (1991) indicano un'avanzata del ghiacciaio di pisgana (adamello) successiva a 3015±75 bp e precedente a 2345±125 bp, che potrebbe corrisponde allo stadio calderone 2. orombelli & porter (1982) documentano un'avanzata del ghiacciaio della brenva (m. bianco) che ha prodotto la sepoltura, da parte di una morena, di un tronco datato 1170±75 anni bp (760÷980 cal. ad); strumia (1997) ha rinvenuto un suolo sepolto da un'avanzata del ghiaciaio del lys, datato 1185±80 anni bp (734÷980 cal. ad); questa avanzata dei ghiacciai alpini sembra corrisponde allo stadio calderone 3a del gran sasso. sulle alpi, a partire da xv secolo, cioé durante la piccola età glaciale si sono poi verificate molte avanzate glaciali, anche notevoli (per una sintesi vedasi baroni,2000), che appaiono quindi correlabili, nel complesso, agli stadi calderone 3b,c. ccoorrrreellaazziioonnee ttrraa aavvaannzzaattee ggllaacciiaallii eedd aallttrrii eevveennttii cclliimmaattiiccii iinn iittaalliiaa cceennttrraallee per tentare un migliore inquadramento cronologico delle fasi di espansione del ghiacciaio del calderone, si ritiene lecito fare ricorso al confronto con dati paleoclimatici rilevati in altre zone dell'italia centrale, in particolare alle oscillazioni di livello dei laghi. il primo riferimento é al lago del fucino, bonificato alla fine del xix secolo. questo lago, posto circa 50 km a sud del corno grande, tra le montagne abruzzesi, ha avuto negli ultimi 30.000 anni, ma anche in dettaglio nei secoli dal xvii al xix, oscillazioni di livello ben correlabili con le variazioni glaciali alpine ed appenniniche (giraudi, 1998). il lago aumentava di livello prevalentemente in concomitanza con le avanzate glaciali e diminuiva in corrispondenza delle fasi di ritiro. negli ultimi 3000 anni, il lago del fucino subì varie oscillazioni: la prima fase di incremento di livello del lago é successiva ad un manufatto in legno datato 2960±100 e precedente a ceramiche attribuite al periodo ii ÷ iii secolo b.c.: tale aumento può essere ritenuto sincrono con lo stadio calderone 2; considerando che il suolo coperto é datato 2650±50 bp, l'espansione glaciale deve essere datata tra circa 2600 e 2200÷2300 anni bp (vii ÷ iii/ii secolo bc); un nuovo aumento di livello ebbe luogo nel periodo compreso tra la sedimentazione di due orizzonti di torba che, per la quota di rinvenimento, sono indicatori di lago basso; la prima torba é stata datata 1375±75 (data calibrata: 630÷690 ad, cioé vii secolo ad), la seconda torba é stata datata 930±125 (data calibrata: 1000÷1250 ad, cioé secoli xi/xiii ad); tale aumento deve coincidere con lo stadio calderone 3a; nuovi forti aumenti di livello sono documentati a partire dal xvi secolo ad, con livelli particolarmente elevati nei primi anni del xvii secolo, nel secondo e nel sesto decennio del xix; tali oscillazioni coincidono quindi con gli stadi calderone 3b,c. a causa della mancanza di dati e delle opere di bonifica romana, le oscillazioni di livello del fucino dal i al iv secolo ad e nel periodo tra x e xvi secolo ad non sono ben conosciute. ma il lago del fucino non é l'unico lago in italia centrale ad avere avuto oscillazioni legate alle stesse fasi climatiche che hanno prodotto le espansioni dei ghiacciai: anche il lago trasimeno (umbria) presenta oscillazioni di livello estremamente interessanti per il presente lavoro. secondo gambini (1995, 2000), che ha studiato i resti di insediamenti umani lungo le sponde, il lago trasimeno, mostra livelli bassi nel periodo etruscoromano fino almeno al iv secolo ad, causato probabilmente dalla presenza di una galleria di drenaggio; in assenza di regimazione, i livelli del lago furono molto bassi nei secoli xi÷xii ad ed aumentarono nel corso del xiii e xiv secolo. il lago raggiunse quote tanto elevate che, nel xv secolo, il suo livello venne controllato mediante una galleria artificiale e la diversione di un corso d'acqua; la presenza del drenaggio non impedì il verificarsi di forti aumenti, che durarono alcuni anni, nel primo decennio del xvii secolo, tra il settimo e l'ottavo decennio del xviii secolo, e nel secondo decennio del xix secolo. 153le oscillazioni del ghiacciaio del calderone ... c'é quindi un'ottima correlazione tra le variazioni di livello del periodo post-romano dei laghi fucino e trasimeno. ne deriva che la fase fredda che ha dato luogo all'avanzata glaciale calderone 3a deve essere responsabile anche dell'aumento di livello lacustre terminato in un momento imprecisato precedente al secolo xi ad e che l'espansione glaciale calderone 3b deve essere successiva al xv secolo ad. le variazioni dei limiti nivali (ela) nel corso degli stadi calderone 2, 3a,b,c, possono fornire indicazioni sulle differenze di temperatura media annua tra le fasi di maggiore estensione del ghiacciaio del calderone e quella attuale. la quota di ela attuale deve essere superiore all'altezza del gran sasso (2912 m). infatti gellatly et al. (1994) riferiscono che almeno dalla fine degli anni '70 il ghiacciaio non é mai stato visto con neve residua degli anni precedenti. la massima espansione della piccola età glaciale indica che ela era a quote non superiori a 2730 m, con una differenza rispetto all'attuale di almeno 180 m. se si tiene conto che il gradiente medio di temperatura al gran sasso, calcolato in base ai dati di tonini (1961) é di circa 0,6°c per ogni 100 m, si può ipotizzare che, a parità di precipitazioni, la temperatura media annua attuale superi di almeno 1,1°c quella del periodo più freddo della piccola età glaciale. la differenza tra ela delle espansioni glaciali precedenti e quella attuale, implicano che nel corso di fasi particolarmente fredde del periodo vii ÷ iii/ii secolo bc la temperatura media annua doveva essere inferiore di almeno 0,8°c, e nel corso dell'espansione glaciale precedente al x secolo doveva essere inferiore di almeno 0,9°c rispetto all'attuale. ccoonncclluussiioonnee lo studio di detriti di origine glaciale posti a ridosso o appena a valle della soglia del circo del ghiacciaio del calderone, ha fornito elementi per l'inquadramento cronologico di alcune fasi di espansione glaciale avvenute nel corso degli ultimi 3000 anni. la cronologia di tali fasi appare ben correlabile con quella delle avanzate dei ghiacciai alpini. l'esame di altri dati di carattere paleoclimatico relativi all'italia centrale ha permesso di validare i dati rilevati e di ottenere una più precisa datazione delle avanzate glaciali. il confronto tra le variazioni di ela rispetto all'attuale ha permesso di valutare anche lo scostamento delle temperature medie rispetto al giorno d'oggi. un'espansione glaciale, databile tra i secoli vii e iii÷ii bc, ha dato luogo alle morene dello stadio calderone 2; nel corso delle fasi più fredde, la temperatura media annuale doveva essere almeno 0,8°c inferiore all'attuale. una successiva espansione glaciale, databile tra il vii ed il x secolo ad, ha dato luogo alle morene dello stadio calderone 3a; nel corso delle fasi più fredde, la temperatura media annuale doveva essere almeno 0,9°c inferiore all'attuale. un'ulteriore espansione glaciale, la più estesa, databile tra xvi e parte del xix secolo ad, quindi attribuibile alla cosiddetta piccola età glaciale, ha dato luogo alle morene dello stadio calderone 3b; nel corso delle fasi più fredde, la temperatura media annuale doveva essere almeno 1,1°c inferiore all'attuale. l'ultima espansione glaciale, databile al xix secolo e quindi alla parte finale della piccola età glaciale, ha prodotto le morene presenti non lontano dalla posizione del fronte glaciale documentato verso la fine del xix secolo; nel corso delle fasi più fredde, la temperatura media annua doveva essere almeno 0,9°c inferiore all'attuale. nei periodi compresi tra le espansioni glaciali, vi erano fasi caratterizzate da clima più caldo; per queste non é possibile calcolare ela (e quindi la differenza di temperatura rispetto all'attuale) a causa della mancanza delle tracce glaciali, asportate dalle avanzate successive. tuttavia é possibile parlare di contrazione dei ghiacciai per il periodo successivo ai secoli iii÷ii bc e precedente al vii secolo ad, per quello che va almeno dal secolo xi al xiii ad e infine per il periodo successivo al xix secolo ad. rriinnggrraazziiaammeennttii lavoro eseguito con il contributo dell'ente parco nazionale del gran sasso e monti della laga. rriiffeerriimmeennttii bbiibblliiooggrraaffiiccii baroni c. (2000) il comportamento dei ghiacciai alpini in risposta alle variazioni climatiche oloceniche. in: antonioli et al. : le fluttuazioni del clima nel corso dell'olocene: stato dell'arte. il quaternario, 1133(1), 100-103. baroni c. & carton a. (1991) vedretta di pisgrana (gruppo dell'adamello). geomorfologia e variazioni oloceniche della fronte. natura bresciana, ann.museo civ. sc. nat. brescia, 2266. d'orefice m., le donne l., pecci m., smiraglia c. & ventura r. (1996) nuovi dati sull'alimentazione nevosa del ghiacciaio del calderone (gran sasso d'italia, appennino centrale). geogr.fis. din. quat., 1188, 253-256. federici p. r. (1979). una ipotesi di cronologia glaciale würmiana, tardo e post-würmiana nell'appennino centrale. geogr. fis. dinam. quat., 22, 196-202. fiucci a., gigante b., rossi c., smiraglia c. & veggetti o. (1997) the calderone glacier (gran sasso d'italia). determination of ice thickness and bedrock morphology by means of radio-echo sounding. geogr. fis. dinam. quat., 2200, 305-308. gambini e. (1995) le oscillazioni di livello del lago trasimeno. quaderni del museo della pesca del lago trasimeno-2, 139 pp. gambini e. (2000) i villaggi sommersi del lago trasimeno. quaderni del museo della pesca del lago trasimeno-5, 117pp. gellatly a.f., grove j.m. & smiraglia c. (1992) alcuni risultati di recenti ricerche sul ghiacciaio del calderone (gran sasso d'italia, abruzzo). geogr. fis. din. quat., 1155, 111-113. gellatly a.f., smiraglia c., grove j.m. and latham r. (1994). recent variations of ghiacciaio del 154 c. giraudi calderone, abruzzi, italy. journal of glaciology. 4400, 486-490. giraudi c. (1998) late pleistocene and holocene lake level variations in fucino lake (abruzzo central italy) inferred from geological, archaeological and historical data. esf workshop "palaeohydrology as reflected in lake-level changes as climatic evidence for holocene times". palaoklimaforschung, 2255, 1-17. gustav fisher verlag ed. giraudi c. (2000) le oscillazioni oloceniche del ghiacciaio del calderone, gran sasso d'italia (abruzzoitalia). il quaternario, 1133(1/2), 31-38. jaurand e. (1994). les heritages glaciaire de l'apennin. thèse pour le doctorat dès lettres de l'université de paris i panthéon-sorbonne. 600 pp. marinelli o. & ricci l. (1916) alcune osservazioni sul ghiacciaio del gran sasso. riv. geogr. it., 2233, 399-405. matthews j.a. (1993) radicarbon dating of buried soils with particular reference to holocene solifluction. in: solifluction and climatic variation in the holocene. palaoklimaforschung-palaeoclimate research. special issue: european palaeoclimate and man-6. 1111, 309-324. orombelli g. & pelfini m. (1985) una fase di avanzata glaciale nell'olocene superiore, precedente alla piccola glaciazione, nelle alpi centrali. rend.soc.geol.it., 88, 17-20. orombelli g. & porter s.c. (1982) late holocene fluctuations of brenva glacier. geogr.fis.dinam.quat. 55, 13-37. smiraglia c. & veggetti 0. (1991) il ghiacciaio del calderone nel gran sasso d'italia. variazioni recenti e relazioni col clima. atti convegno "le variazioni recenti del clima (1800-1900) e le prospettive per il xxi secolo. mem.soc. geogr. it., 4466, 183-198. smiraglia c. & veggetti 0. (1992) recenti osservazioni sul ghiacciaio del calderone (gran sasso d'italiaabruzzo). boll. soc. geogr. it., ser.xi,44, 269-302. strumia g. (1997) oscillazioni glaciali precedenti la piccola età glaciale documentate da un suolo sepolto in una morena del ghiacciaio del lys. il quaternario, 1100(2), 153-158. tonini d. (1961). il ghiacciaio del calderone del gran sasso d'italia. bollettino del comitato glaciologico italiano 1100, 71-134. ms. ricevuto il 3 gennaio 2002 testo definitivo ricevuto il 26 febbraio 2002 ms. received: junuary 3, 2002 final text received: february 26, 2002 impaginato atti ccoonnffrroonnttoo ttrraa iinnffoorrmmaazziioonnii ggeeoollooggiicchhee ee ppeeddoollooggiicchhee ssuull ccoonnooiiddee ddeell cceelllliinnaa ((ffrriiuullii,, iittaalliiaa)) rr.. aavviigglliiaannoo11,, gg.. mmoonneeggaattoo11,, ss.. zzaannoollllaa22,, gg.. mmiicchheelluuttttii22 && pp.. mmoozzzzii33 1università degli studi di udine, dipartimento di georisorse e territorio 2ersa, ente regionale per lo sviluppo e la promozione dell’agricoltura del friuli-venezia giulia, ufficio del suolo 3università degli studi di padova, dipartimento di geografia riassunto su un conoide terrazzato sono state analizzate le caratteristiche dei suoli sviluppatisi su ordini di terrazzi attribuibili ad età diverse, sui quali è stata testata l'applicabilità degli indici chimici proposti in letteratura per la datazione relativa dei suoli. i depositi alluvionali del conoide del cellina sono costituiti esclusivamente da clasti di rocce sedimentarie con prevalenza di litotipi calcareo-dolomitici rispetto a quelli terrigeni; l’evoluzione geomorfologica è stata influenzata sia dal contesto tettonico, sia dalle variazioni nel tempo dei fattori che controllano il regime delle portate solide e liquide del corso d’acqua. sono stati confrontati sette suoli rappresentativi ubicati sulla superficie del conoide ed un suolo sepolto rinvenuto in prossimità dell’alveo attuale sotto una coltre sedimentaria di circa 30 m. il grado di pedogenesi dei suoli ed una stima sommaria della loro età sono stati valutati anche utilizzando due indici relativi alle diverse forme di ferro presenti, estratte in ossalato e ditionito-citrato: l’air (feo/fed) e l’arduino ((fed-feo)/fetot). il rapporto fra forme di ferro libero ed il ferro totale non ha tuttavia portato ad una migliore comprensione della cronostratigrafia dei corpi sedimentari, in quanto nella peculiarità sedimentologica di questo ambiente il ferro totale misurato sulla terra fine rappresenta già una concentrazione residuale dovuta all’alterazione, come viene evidenziato sia dal suo aumentare con l’età presunta, sia dal suo diminuire negli orizzonti non pedogenizzati. summary seven soils located on terraces of different ages of an alluvial fan in north-eastern italy have been compared in terms of their morphology and degree of development. alluvial deposits deriving from calcareous-dolomitic rocks, with subordinated terrigenous rocks, always represent the parent material. there are no crystalline rocks outcrops in the mountain basin. the geomorphological evolution of the alluvial fan has been strictly controlled both by the still active tectonics of the area and by the long-term variability of climatic factors. one (profile f) is located on the holocene fan and presents a low degree of development, two, profiles c and e, are on the main surface of the pleistocene fan, dated 10530 ± 100 ybp, conventional 14c age. the different degree of development is probably due to the difference in parent material, very coarse gravel with boulders in profile c, gravel in profile e. profile d is on a higher terrace, but is similar to those on the main surface. profiles g and b are located on small portions of terraces, probably in a tectonics-affected position, at the very border of the alluvial plain. profile h is a buried soil, outcropping under a 30m thick gravel deposit. extractable iron ratios have also been considered in order to determine whether they are affected by their relative ages. free ironoxide/total-iron ratios, according to the air and arduino methods, gave unattended results. it has not been possible to recognise a trend with the increasing age and the range of values obtained is much greater than those known by literature. a possible explanation is in the peculiar characteristics of the area, where even the content of total-iron alone offers a trend of development, as can be evinced by its increasing with relative age and decreasing with depth. parole chiave: ferro libero; geologia del quaternario; conoide alluvionale; torrente cellina; friuli key-words: free iron; quaternary geology; alluvial fan; cellina river; friuli il quaternario italian journal of quaternary sciences 1155(1), 2002, 99-104 11.. iinnttrroodduuzziioonnee in geologia per l’analisi stratigrafica dei depositi quaternari continentali vengono sempre più diffusamente utilizzate le uunniittàà aalllloossttrraattiiggrraaffiicchhee (“corpi di rocce sedimentarie cartografabili, definiti e identificati sulla base delle discontinuità che li delimitano”, north american commission on stratigraphic nomenclature, 1983). le discontinuità che delimitano i corpi sedimentari possono essere di varia natura, in ogni caso rappresentano lacune temporali (mancata sedimentazione per periodi di tempo più o meno lunghi) e/o sedimentarie (superfici erosive). i corpi geologici compresi tra discontinuità di rango superiore e con estensione regionale di regola appartengono a cicli sedimentari che possono essere legati a importanti variazioni climatiche e a particolari fasi di evoluzione tettonica dell’area. nelle serie sedimentarie di ambiente continentale il rango gerarchico tra le discontinuità, superficiali o sepolte, legate a lacune temporali dipende dalla durata del periodo di mancata sedimentazione e dalla loro estensione, esso è quindi intimamente connesso alle caratteristiche dei suoli che possono essere ad esse associati. da questa premessa diventa evidente che l’analisi di suoli superficiali e sepolti fornisce indicazioni importanti per definire la gerarchia e l’estensione delle discontinuità, nonché la geometria dei corpi sedimentari. per quanto riguarda i corpi sedimentari superficiali affioranti, la loro età relativa è ricavata prevalentemente da evidenze geomorfologiche, stratigrafiche e dal grado di alterazione pedogenetica delle loro superfici limite superiori. nel caso in cui le superfici pedogenizzate siano svincolate dal contesto geomorfologico e stratigrafico originario (lembi isolati di terrazzi fluviali, evidenze sporadiche di suoli sepolti), diventa di fondamentale importanza la correlazione tra suoli osservati in contesti diversi per la ricostruzione delle morfologie originali e dei rapporti tra i corpi sedimentari. in questo lavoro si analizzano alcuni suoli, sia superficiali che sepolti, sviluppatisi su depositi alluvionali del torrente cellina (alta pianura pordenonese) tentando di confrontare le osservazioni pedologiche “di routine” effettuate nel corso di un rilevamento finalizzato alla cartografia dei suoli, con le caratteristiche chimiche dei suoli e con dati di tipo geomorfologico e geologico stratigrafico. per alcuni suoli il ritrovamento di sedimenti organici vegetali ha consentito di definire l’età 14c convenzionale dei depositi sui quali si sono sviluppati, per altri non si hanno elementi di datazione dei depositi per cui si fa riferimento solo ad una cronologia relativa. oltre all'osservazione delle caratteristiche morfologiche dei suoli, si è voluto testare l'applicabilità all’ambiente in esame degli indici chimici proposti in letteratura per la datazione relativa dei suoli. in pratica questi indici si propongono di confrontare il contenuto di ferro libero con il ferro totale, dove il primo costituisce il ferro liberato dalla pedogenesi ed il secondo l’ammontare fra questo e quello legato al reticolo dei silicati. questo approccio interdisciplinare è stato possibile grazie alla collaborazione tra il dipartimento di georisorse e territorio dell'università di udine e l’ersa del friuli-venezia giulia nell'ambito dei rispettivi progetti carg fvg (nuova cartografia geologica nazionale in fvg) e sols (banca dati georeferenziata dei suoli della pianura e delle colline del fvg), con la partecipazione del dipartimento di geografia dell'università di padova. 22.. iinnqquuaaddrraammeennttoo ggeeoollooggiiccoo ee ggeeoommoorrffoollooggiiccoo il conoide alluvionale del torrente cellina è originato dalle divagazioni del corso d’acqua al suo sbocco nella pianura veneto friulana. esso si sviluppa al limite tra le prealpi carniche pordenonesi, nelle quali si espande il suo bacino imbrifero, e la pianura prospiciente il mare adriatico (fig.1). l’evoluzione geomorfologica del conoide su ambiti temporali medio-lunghi è presumibilmente influenzata 100 r. avigliano et al. fig. 1 schema geomorfologico della pianura friulana occidentale (da stefanini & cucchi, 1978, mod.). geomorphological sketch of the western friuli plain (from stefanini & cucchi, 1978, mod.). 101confronto tra informazioni geologiche ... da un lato dal generale contesto tettonico in cui è inserito, dall'altro dalle variazioni nel tempo dei fattori prevalentemente climatici che hanno controllato il regime delle portate solide e liquide del corso d’acqua. il margine meridionale dei rilievi alpini assume qui un andamento ne-sw, condizionato dalla presenza di importanti strutture tettoniche di uguale direzione. il sollevamento di questa porzione di catena ha fatto sì che in pianura, già in prossimità dell’apice del conoide, i depositi alluvionali che ricoprono il substrato prequaternario posto ai piedi del thrust abbiano spessori di alcune centinaia di metri e che lembi di depositi fluviali siano rimasti isolati sui versanti dei rilievi prospicienti la pianura. a due di questi lembi si riferiscono i pprrooffiillii bb (terrazzo di aviano) e gg (terrazzo di maniago libero) sospesi rispettivamente di circa 10 e 30 m sulla superficie del conoide tardo-pleistocenico (comel, 1956; avigliano et al., 2001). le superfici di questi terrazzi possono aver subito, nel tempo, un rimodellamento anche molto spinto; tuttavia i suoli sviluppatisi su di essi sono decisamente più evoluti rispetto a quelli del conoide più recente e eventuali superfici a loro omologhe in pianura vanno ricercate all'interno del materasso alluvionale. i depositi alluvionali recenti e antichi osservati nella zona apicale del conoide sono simili, trattandosi prevalentemente di ghiaie a ciottoli e blocchi clastosostenuti con matrice sabbiosa, massive o a stratificazione grossolana, che possono essere cementati nel caso dei sedimenti più antichi. verso l'unghia del conoide diminuiscono gradualmente le dimensioni dei clasti, i depositi sono sciolti, meglio classati ed assumono una stratificazione orizzontale e inclinata ben definita fino a diventare comune la presenza di corpi prevalentemente sabbiosi. la litologia dei depositi alluvionali costituenti il conoide riflette quella delle rocce affioranti nel bacino montano del cellina che sono esclusivamente sedimentarie con netta prevalenza delle calcareo dolomitiche sulle terrigene, mentre mancano totalmente le rocce cristalline. il conoide del cellina risulta formato da un “conoide principale”, costituito da un insieme di costruzioni coalescenti aventi apice comune. la superficie del conoide è rimasta in evoluzione almeno fino al termine del pleistocene superiore come sembrano confermare alcune datazioni radiometriche effettuate con il metodo del radiocarbonio su sedimenti organici campionati in prossimità di essa (maniago: 11850 ± 110 ybp; basaldella di vivaro: 10530 ± 100 ybp età 14c non calibrate. avigliano et al., 2001). sulla superficie del conoide principale sono stati osservati i pprrooffiillii cc,, ee e dd, quest’ultimo situato su un terrazzo convergente (riva di bares) presente sul margine nw del conoide e che ne rappresenta probabilmente la porzione più antica. a partire dal passaggio tra pleistocene e olocene, nel tratto apicale del conoide principale, l’erosione ha incominciato a prevalere sulla deposizione. durante l’olocene la tendenza erosiva del corso d’acqua in questo settore sembra essere stata continua e si è accompagnata alla migrazione verso sud dell’area di sedimentazione con conseguente formazione di un “conoide telescopico” che si sovrappone all’unghia del conoide principale e su cui è stato osservato il pprrooffiilloo ff. durante la fase di incisione il cellina ha progressivamente spostato verso ovest il suo asse, come testimoniato dalla serie di terrazzi di erosione convergenti presenti sull’ala sinistra del conoide. fig. 2 sezione schematica del conoide del t.cellina in località del ponte del giulio, in corrispondenza dell’affioramento del paleosuolo descritto nel profilo h. schematic section of the river cellina fan with the palaeosoil outcrop (profile h). 102 r. avigliano et al. attualmente il corso d'acqua incide l’apice del conoide principale con scarpate che arrivano ai 40 m di altezza. a montereale valcellina, in località ponte del giulio, il cellina incide il conoide per circa 30 m. in corrispondenza del greto l'erosione ha esumato un suolo sepolto ben sviluppato (pprrooffiilloo hh) che testimonia una importante lacuna sedimentaria in questo settore della pianura precedentemente all'ultima fase di aggradazione (fig. 2). si ritiene che la formazione del suolo sia collegata ad una situazione morfologica simile a quella attuale, in cui la pianura era terrazzata ed il corso d’acqua scorreva incassato all’interno di un’incisione. per il momento non sono chiari i rapporti tra il suolo del ponte del giulio e quelli sviluppatisi sui depositi tettonizzati (pprrooffiillii bb e gg), nonché quali siano stati i fattori che hanno maggiormente influito sul presunto antico approfondimento del corso d'acqua e che stanno quindi all'origine della lacuna sedimentaria (fattori climatici, tettonici o entrambi). 33.. ii ssuuoollii nell’area oggetto di studio sono stati scelti, tra quelli effettuati nell’ambito del progetto sols, i profili di sette suoli rappresentativi per inquadrarne le caratteristiche e confrontare il loro grado di sviluppo (fig 3). le osservazioni hanno confermato la presenza di suoli più sviluppati sulle superfici supposte più antiche (terrazzi di aviano e maniago libero), con lisciviazione dei carbonati ed illuviazione di argilla negli orizzonti profondi (pprrooffii-llii bb e gg). la superficie del conoide principale tardo pleistocenico è invece contraddistinta da suoli mediamente poco sviluppati (pprrooffiilloo cc), le cui caratteristiche appaiono condizionate più dalla natura essenzialmente carbonatica e dalla granulometria del materiale di partenza che dalla loro età. infatti il pprrooffiilloo dd, ubicato sulla porzione di conoide supposta più antica, non presenta grandi differenze rispetto al pprrooffiilloo cc, mentre, all’interno della stessa fig. 3 carta dei sottosistemi di terre ed ubicazione dei profili. land subsystem map and profile location. iidd ccoommuunnee qquuoottaa ppaaeessaaggggiioo uussddaa ((11999988)) wwrrbb ((11999988)) pprrooffiilloo mmssllmm bb aviano 155 terrazzo fluviale typic cutani-chromic tettonizzato hapludalf luvisol cc montereale 238 superficie modale typic skeleti-rendzic valc. del conoide haprendoll leptosol pleistocenico dd aviano 227 terrazzo fluviale rendollic skeleti-calcaric eutrudept cambisol ee s. quirino 116 superficie modale rendollic skeleti-calcaric del conoide eutrudept cambisol pleistocenico ff s. quirino 131 superficie modale typic skeleti-calcaric del conoide udorthent regosol olocenico gg maniago 350 terrazzo fluviale spodic hyperdistritettonizzato paleudult profondic alisol hh montereale 241 suolo sepolto typic cutanic luvisol valc. hapludalf tab. 1 classificazione dei suoli. soil classification. unità di paesaggio, i suoli impostati su sedimenti più fini presentano un grado di sviluppo maggiormente accentuato (pprrooffiilloo ee). infine, è stato considerato un suolo impostato su una superficie di deposizione recente, che ha messo in luce come l’instaurarsi della pedogenesi sia estremamente lento (pprrooffiilloo ff). le caratteristiche delle diverse tipologie di suolo sono state confrontate con quelle di un suolo sepolto (pprrooffiilloo hh) rinvenuto nell’alveo 103confronto tra informazioni geologiche ... attuale del torrente cellina nell’ambito dei rilevamenti carg, evidenziando come questo presenti delle analogie con quelli rilevati sui terrazzi di aviano e di maniago libero. 44.. iinnddiiccii cchhiimmiiccii ppeerr llaa ddaattaazziioonnee rreellaattiivvaa ddeeii ssuuoollii il grado di pedogenesi dei suoli ed una stima sommaria della loro età sono stati valutati utilizzando due indici: l’air (torrent et al., 1980) e l’arduino (arduino et al., 1984) tramite la determinazione delle diverse forme del ferro (totale, ossalato, ditionito-citrato), estratte in accordo con i metodi ufficiali (ministero delle risorse agricole, alimentari e forestali, 1994). l’air (active iron ratio) è definito dal rapporto tra il ferro estratto in ossalato e quello estratto in ditionitocitrato (feo/fed) e dovrebbe decrescere con l’aumentare del grado di alterazione del parent material. l’indice di arduino ((fed-feo)/fetot), espresso in percentuale, dovrebbe invece aumentare con l’età supposta del suolo. l’estrazione è stata effettuata su ciascuno degli orizzonti riconosciuti nel profilo, ed ha evidenziato come il tenore in ferro tenda a diminuire con la profondità, ad eccezione dei suoli con un orizzonte b ben sviluppato, dove generalmente il valore si mantiene costante o tende ad aumentare rispetto agli orizzonti sovrastanti. per ciascun profilo è stato identificato un orizzonte significativo del grado di pedogenesi raggiunta, corrispondente ad un b per i profili maggiormente sviluppati, all’ a negli altri casi, che è stato successivamente messo a confronto con gli altri. 55.. ccoonncclluussiioonnii l’applicazione degli indici arduino e air non ha fornito i risultati attesi (fig. 4). l’analisi dei dati evidenzia che non solo non è presente un trend riconoscibile, ma anche che l’intervallo di variabilità osservato è più ampio di quello riscontrato da altri autori per lo stesso intervallo di tempo (arduino et al., 1983; bini e mondini, 1992). ritenendo che il materiale parentale dei diversi suoli presenti un buon grado di uniformità litologica, l’origine di questa discrepanza sembra risiedere nel diverso contenuto in ferro totale posseduto dai campioni di terra fine (frazione < 2mm) analizzati. considerando invece il contenuto di ferro totale nei confronti dell’età presunta si evidenzia invece un trend ben marcato, dove esso tende ad aumentare con l’età. un andamento analogo si riscontra anche per il contenuto di ferro estratto in ossalato e in ditionito-citrato, entrambi indice del grado di alterazione a parità di contenuto di ferro totale nel materiale parentale (fig. 5). essendo il ferro un costituente accessorio delle alluvioni grossolane prevalentemente calcareo-dolomitiche del cellina, il rapporto fra forme di ferro libero ed il ferro totale non porta a risultati significativi, in quanto il ferro totale misurato sulla terra fine rappresenta già di per sé una concentrazione residuale dovuta all’alterazione. ciò è suffragato dal fatto che il tenore in ferro totale è minore negli orizzonti c rispetto a quelli pedogenizzati. non è tuttavia ancora possibile, sulla base dei dati disponibili, tracciare l’andamento di una curva sperimentale rispetto al tempo e stabilire pertanto i rapporti che intercorrono tra le superfici su cui sono ubicati i profili b, g ed h. profilo scheletro % sabbia % limo % argilla % ph in acqua carbonati carbonio ffeerrrroo iinn ffeerrrroo iinn ffeerrrroo v/v (2000-50 (50-2 (<2 um) totali % organico oossssaallaattoo ddiittiioonniittoo ttoottaallee um) um) % gg//kkgg gg//kkgg gg//kkgg bb 3 8,1 18,0 73,9 7,6 1 0,5 44,,55 2277,,11 5522,,22 cc 63 37,4 56,3 6,3 8,0 64 3,0 11,,88 1111,,99 1122,,22 dd 36 30,2 49,2 20,5 8,1 35 1,9 22,,00 1166,,88 2244,,22 ee 64 31,8 38,7 29,5 7,9 45 1,2 11,,33 1177,,55 2299,,44 ff 58 61,0 34,7 4,4 7,6 92 1,8 00,,55 22,,88 33,,88 gg 18 5,0 22,1 72,9 5,3 0 0,3 33,,66 2288,,99 5588,,88 hh 7 16,6 12,0 71,3 8,0 0 0,4 44,,44 2255,,99 5544,,22 tab. 2 dati analitici relativi agli orizzonti considerati. analytic data of the selected horizons. fig. 4 indici di arduino e air. arduino and air indexes. bbiibblliiooggrraaffiiaa aa. vv. (1994) – metodi ufficiali di analisi chimica del suolo. osservatorio nazionale pedologico e per la qualità del suolo, ministero delle risorse agricole, alimentari e forestali, roma. aa. vv. (1998). keys to soil taxonomy, eight edition, united states departement of agriculture, natural resources conservation service. aa. vv. (1998). world reference base for soil resources, fao, isric and isss. arduino e., barberis e., carraro f. forno m. g. (1984) – estimating relative ages from iron-oxide/total iron ratios of soils in the western po valley, italy. geoderma, 3333 p. 39-52, elsevier science publishers b. v. amsterdam. avigliano r., calderoni g., monegato g. mozzi p. (2001) – the late pleistocene-holocene evolution of the cellina and meduna alluvial fans. atti dell'80ª riunione estiva della sgi. memorie della società geologica italiana. (in stampa) bini c., mondini c. (1992) – deep weathering features in paleosols from alluvial deposits (“terra rossa”like) in the friuli piedmont area (italy). miner. petrogr. acta, vvooll.. xxxxxxvv, 1-21. comel a. (1956) monografia sui terreni della pianura friulana. iii. genesi della pianura occidentale costruita dal meduna, dal cellina e da corsi d'acqua minori. n. ann. ist. chim. agr. sperim. gorizia, 7: p. 5-93, gorizia. mondini c., bini c. ciet p., paronuzzi p., spadea p. (1991) – clay mineralogy of a soil chronosequence in the friuli piedmont area. proc7 th euroclay conf. dresden ’91, greiswald 779-784. north american commission on stratigraphic nomenclature (1983) north american stratigraphic code. the american association of petroleum geologists bullettin, 6677((55)): p. 841-875, tulsa. stefanini s. & cucchi s. (1978) gli acquiferi del sottosuolo della pianura veneta fra i fiumi piave e tagliamento. c.n.r., quaderni dell'ist. di ric. sulle acque, 3344 ((1122)): p. 287-299. torrent j., schwertmann u. and schulze d.j. (1980) iron oxide mineralogy of some soils of two river terrace sequences in spain. geoderma 2233,, 191208. 104 r. avigliano et al. fig. 5 valori di ferro estraibile. extractable iron. ms. ricevuto marzo 2002 ms. received: march 2002 microsoft word 01_bergami_lm02.doc available online http:/amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 26 (1), 2013, 5-14 ionian sea surface temperature during the sapropel s1 deposition inferred from planktonic foraminiferal mg/ca and δ18o caterina bergami1, lucilla capotondi1, daniela salvagio manta2, mario sprovieri2, luigi vigliotti1 1 cnr istituto di scienze marine, ismar, bologna, italy 2 cnr istituto per l’ambiente marino costiero, iamc, capo granitola, trapani, italy corresponding author: caterina bergami <caterina.bergami@ismar.cnr.it > abstract: temperature variations during the holocene sapropel s1 has been investigated by means of a multiproxy study on core et99-m11 collected in the western ionian sea at a water depth of 2800 m. sea surface temperatures (sst) reconstruction has been made by measuring oxygen stable isotopes (δ18o) and mg/ca ratios on the planktonic foraminifers globigerinoides ruber and globigerina bulloides. results indicate that the investigated interval was characterized by water temperature increase, both at surface and in the sub-surface layers. paleotemperature reconstruction based on mg/ca ratios shows higher temperature values during the two sub-units (s1a and s1b) of the sapropel s1, and lower during the sapropel interruption, the latter being synchronous to the well known 8.2 cold event. in addition, a number of several short-term cold oscillations which can be correlated with millennial scale climate events in the north atlantic region is evidenced. this indicates a possible atmospheric connection between the central mediterranean and the north atlantic region and the strong relation between climate and oceanographic changes during the sapropel deposition. keywords: sapropel s1, planktonic foraminifera, paleotemperature, central mediterranean, mg/ca. 1. introduction organic-rich layers, named sapropels, characterize the neogene sediments of the mediterranean sea (olausson, 1961; cita et al., 1977). these sediments contain abundant and well-preserved planktonic microfossils that make these intervals particularly suitable for high-resolution paleoclimatic reconstructions. planktonic foraminifera have proven to be excellent indicators of sea surface temperature, salinity, food availability and they have been used to detect longand short-term climate changes in the mediterranean sea. actually, the isotopic and trace elements composition of foraminifera shells provide a reliable record of seawater chemistry and as such are widely used by palaeoceanographers to reconstruct ocean and climate variability on geological timescales. specifically, the δ18o signal of planktonic foraminifera records the combined effects of global ice volume, sea surface temperature, and regional evaporation/precipitation budgets, while the mg/ca ratio of foraminiferal tests mainly depends on the temperature of the water in which the foraminifer calcifies, as basically deduced from cultivating work and field studies (e.g., nürnberg, 1995, 2000; nürnberg et al., 1996, 2000; lea et al., 1999; mashiotta et al., 1999; elderfield & ganssen, 2000: dekens et al., 2002). foraminiferal mg/ca seawater thermometry is a rapidly developing and increasingly widely used tool for palaeoceanographic reconstructions (nürnberg et al., 1996; rosenthal et al., 1997; lea et al., 1999; elderfield & ganssen, 2000; lea at al., 2000; anand et al., 2003; barker et al., 2005). the exponential increase of bulk test mg/ca composition with seawater temperature is well established from deep-sea sediment core top (rosenthal et al., 1997; hastings et al., 1998; elderfield & ganssen, 2000; lea at al., 2000; rosenthal et al., 2000; dekens et al., 2002; rosenthal & lohmann, 2002). however, the incorporation of mg during shells calcification is a complex and imperfectly known mechanism with potential species‐dependent effects and non‐temperature biases such as those associated to carbonate ion content of seawater (russell et al., 2004; kisakürek et al., 2008) or salinity (nürnberg et al., 1996; lea et al., 1999; kisakürek et al., 2008; mathien‐blard & bassinot, 2009; arbuszewski et al., 2010). although not numerically abundant, studies in the mediterranean evidenced some problems in the application of this method. ferguson et al. (2008) showed a significant response of foraminiferal mg/ca to salinity in the mediterranean sea revealing a clear relationship (16% mg/ca increase per psu) although associated to a large mg/ca data scattering. this result was later confirmed by sabbatini et al. (2011), on the mg/ca ratios characterizing the planktonic species g. ruber from the whole mediterranean sea. hoogakker et al. (2009) and boussetta et al. (2011), who worked on core tops from the red sea and from the mediterranean basin respectively, suggested that anomalously high mg/ca ratios of planktonic foraminifers from the mediterranean sea, could be also related to early diagenetic, high mg‐calcite overgrowths formed from caco3 supersaturated interstitial seawater. also, van raden et al. (2011) suggested that the high mg/ca measured on two planktonic foraminifers (globigerina bulloides and globorotalia inflata) in the western mediterranean sea is due to inorganic calcite coating on the foraminiferal tests. finally, kontakiotis et al. bergami c. et al. 6 (2011) presented new aegean sea results which reveal mg/ca values that were unreasonably high to be explained by temperature or salinity variations alone, confirming that foraminiferal mg/ca is affected by diagenesis. studies regarding foraminiferal mg/ca ratios during sapropels deposition are rare, however ní fhlaithearta et al. (2010) reliably constrained the magnitude and duration of the sapropel s1 interruption and other shortterm cooling events using mg/ca thermometry from the benthonic microfauna in the aegean sea. here we present oxygen isotopes and mg/ca ratios data from planktonic foraminifera globigerina bulloides and globigerinoides ruber from sediments of sapropel s1 in the ionian sea, with the aim to reconstruct paleotemperature and paleoenvironmental changes which occurred during the sapropel s1 deposition in this basin. 2. regional setting the ionian sea is a transition basin influenced by the flow and transformation of the major water masses constituting the intermediate and deep thermohaline cell of the eastern mediterranean conveyor belt (malanotterizzoli et al., 1997; napolitano et al., 2000). moreover, the ionian circulation plays an important role in the redistribution of the different water masses to adjacent seas (gačić et al., 2010). at the near-surface level, which is the most important part of the water column with regard to the biological production, the modified atlantic water (maw) enters the western ionian basin, the intermediate layer is influenced by salty and warm waters coming from the levantine and aegean basins (liw: levantine intermediate waters), whilst dense and oxygenated waters, mainly of adriatic origin, spread into the ionian deep layer. the choice of the ionian basin for this kind of highresolution study is driven by the fact that its oceanographic setting is critical for the deep-water formation of the mediterranean basin and the oceanographic conditions, responsible of the sapropel deposition, are certainly influenced by the deep-sea ventilation. moreover, concerning the planktonic foraminiferal distribution, this basin appears as a transitional area between the southwestern and eastern mediterranean area (pujol & vergnaud grazzini, 1995). 3. material and methods the sedimentary core et99m11 has been collected in the ionian sea (36°44’04”n, 15°50’94”e, 2800 m below sea level; fig 1). in the core, the sapropel s1 interval is characterized by black-grey sediments extending from 54 to 22 cm depth in section iv of the core (fig. 1). 3.1. age model the age model is that provided by vigliotti et al. (2011 and table 2 therein) based on four 14c ams da fig. 1 location map of the core et99m11 and section iv of the core with the indication of the sapropel s1 position. 450 m resolution dtm retrieved from http://portal.emodnet-hydrography.eu/emodnetportal/index.jsf#. the sapropel s1 in the ionian sea 7 tings integrated with tephra layers and planktonic foraminiferal bioevents. on this base sapropel s1, is chronologically confined between 10.4 and 5.7 cal ka bp and appear synchronous with analogous layer reported in the eastern mediterranean sea. in detail, three different time intervals have been recognized: the s1a sub-unit spanning from 10.4 to 8.3 cal ka bp, the sapropel interruption from 8.3 to 7.8 cal ka bp, and the s1b sub-unit from 7.8 to 5.7 cal ka bp (vigliotti et al., 2011). 3.2. foraminiferal species used and their ecological features g. ruber is a species living in the surface mixed layer and occurring in subtropical to tropical latitudes (deuser, 1987; ravelo & fairbanks, 1992; niebler et al., 1999). it is found at the base of the mixed layer (field, 2004) and even has moderate abundances within the thermocline. in contrast to other species, g. ruber has a low-slope response to a deepening isotherm, which makes this species the most suitable to document nearsurface temperatures when other species are living deeper (field, 2004; tedesco et al., 2007). g. bulloides has a wide geographic distribution, ranging from the poles to the low latitudes (niebler et al., 1999; schmidt & mulitza, 2002). this taxon most commonly lives in the surface mixed layer (fairbanks et al., 1982; hemleben et al., 1989), but it also occurs within the thermocline (field, 2004). each species records the temperature variations of the water mass in which it thrives. hence, the warmest water mass is the one in which g. ruber lives, and corresponds to the summer mixed layer (pujol & vergnaudgrazzini, 1995; rohling et al., 2004). the water mass recorded by g. bulloides is assumed to be a mixture between the late spring/early summer surface layer and deeper waters upwelled during those months at 50-100 water depth (pujol & vergnaud-grazzini, 1995; barcena et al., 2004; hernàndez-almeida et al., 2005). 3.3. trace elements analysis (icp-ms/icp-aes) forty to sixty specimens of g. ruber (var. alba) were selected from the > 150 µm size fraction (26 samples) discarding specimens visibly contaminated by ferromanganese oxides. the foraminifera tests were next cleaned using a multistep trace metal protocol including reductive cleaning with buffered hydrazine (boyle & keigwin, 1985). mg/ca ratios were measured on a inductively coupled plasma mass spectrometer varian icp-ms and an inductively coupled plasma atomic emission spectrophotometer varian vista mpx at the geochemistry laboratory of the iamc-cnr (naples). in detail, the tests were gently crushed and then cleaned following procedures modified from lea & boyle (1993). briefly, samples were ultrasonically cleaned four times with ultrapure water (> 18 mω) and twice with methanol. metal oxide coatings were reduced in a solution consisting of anhydrous-hydrazine, citric acid, and ammonium hydroxide and organic matter was oxidized in a solution of hydrogen-peroxide and sodiumhydroxide. all the water samples were treated under a laminar air flow clean bench to minimize contamination risks and the sampling materials were cleaned with high purity grade reagents. the remaining tests material was then dissolved in 0.1n nitric acid and simultaneously analysed for magnesium with the varian icp-ms inductively coupled plasma-mass spectrometer. a multielement standard was prepared with icp-ms grade high-purity standards. based on repeated analyses of the standard and samples over several runs, on different days, the 2s error in the icp analyses is estimated at ±5%. replicate analyses on five samples yielded an average external precision (1σ) of about 5%. calcium was measured with a varian vista mpx inductively coupled plasma-optical emission spectrometer (icp-oes). metal to calcium ratios were determined from intensity ratios with an external matrix-matched standard using the method developed by rosenthal et al. (1999). the cleaning protocol and analytical approach used in this study is also comparable to methods reported by elderfield & ganssen (2000). 3.4. isotopic analyses the oxygen isotopic composition of g. ruber (var. alba) and g. bulloides were obtained from the sediment core. about 10-15 specimens in the > 150 µm size fraction were analyzed per sample (41 samples). samples were measured with an automated continuous flow carbonate preparation gasbench ii device and a thermoelectron delta plus xp mass spectrometer at the laboratory of geochemistry of the iamc-cnr (naples). acidification of the samples was performed at 50°c. an internal standard (carrara marble with δ18o = 2.43‰ vs. vpdb and δ13c = 2.43‰ vs. vpdb) was run every six samples and the nbs19 international standard was measured every 30 samples. standard deviations of carbon and oxygen isotope measures were estimated at 0.1 and 0.08‰, respectively. all the isotope data are reported in δ‰ versus vpdb. 3.5. determination of calcification temperatures 3.5.1. temperature estimates from δ18oforam to obtain the calcification temperatures we have used oxygen isotope data of g. ruber and g. bulloides (δ18oforam) and of the water masses in which they calcify (δ18oseawater). different equations have been proposed to convert δ 18oforam in sst but based on what reported on grauel & bernasconi (2010) on sediment surface samples, g. ruber yield the most reliable calcification temperature applying the shackleton (1974) palaeotemperature equation. in fact, according to the authors, who made a core-top study on δ18o temperature reconstructions of g. ruber (white) and u. mediterranea in the central mediterranean, reliable temperatures were produced using the shackleton (1974) equation, whereas too low temperatures compared to the recent temperature conditions (on average ~4.4°c lower than predicted by shackleton (1974) equation) were produced using the mulitza et al. (2003) equation. the equation of shackleton (1974) is: where tiso is the calcification temperature and δ 18oforam and δ18oseawater are reported vs. vpdb. δ 18oseawater values for sapropel time are those reported in kallel et al. (1997 and table 4 therein). bergami c. et al. 8 values of δ18oseawater have been converted to vienna standard mean ocean water (v-smow)‰ using the following equation:   3.5.2 temperature estimates from mg/ca ratios although in the mediterranean sea seems to be no significant correlation between mg/ca and δ18o‐derived calcification temperatures (ferguson et al., 2008; sabbatini et al., 2011), several studies suggested an exponential correlation between mg/ca ratios from g. ruber shells and sst (e.g. elderfield & ganssen, 2000; anand et al., 2003; dekens et al., 2002). generally, the adopted mg/ca-sst equation is that reported by elderfield & ganssen (2000) based on multispecies calibration:   where tmg/ca is the calcification temperature and mg/ca is measured in mmol/mol. 4. results 4.1. δ18oforam and sst the oxygen isotope data measured on the two species of planktonic foraminifera are illustrated vs. age in fig. 2. the δ18o values from g. ruber and g. bulloides during the investigated period average -0.56‰ and 1.12‰, respectively (fig. 2) with associated variances of 0.46‰ and 0.62‰. g. ruber shows lower values than g. bulloides but the two records show the same trend during the investigated period, with a general lightening during sapropel deposition, and particularly during the s1a subunit. the g. ruber calcification temperature, characterized by a general increase throughout the whole investigated period, ranges between 22.8 and 14.1°c with an average value of 20°c, while g. bulloides records a similar trend with an isotopic temperature ranging between 16.3 and 5.0°c, with an average value of 12.7°c (fig. 2). the heaviest isotopic values throughout the record are observed at 11.6, 10.7, 10.0, 9.5, 8.2, and 6.4 cal ka bp suggesting colder conditions during these intervals. fig. 2 down-core oxygen isotope records (‰ versus vpdb) and calculated isotopic temperature in °c in g. ruber var. alba and g. bulloides for core et99m11 across the sapropel s1. the grey areas, representing the extent of the two sub-units of the sapropel s1, are from vigliotti et al. (2011). b5-b7 label bond cycles (bond et al., 1997; 2001). the sapropel s1 in the ionian sea 9 4.2. mg/ca ratios and sst estimates during the interval of sapropel deposition mg/ca ratios range between 1.8 and 4.7 mmol/mol (fig. 3) with an average value of 3.37 mmol/mol. the estimated sst values range between 22.3 and 15.7°c during the subunit s1a, with an average value of 20°c, and between 22.4 and 18.6°c (average value 18.6°c) during the subunit s1b, while during the interruption the average value is 14.8°c (fig. 4). the warmest period is observed at the beginning of the sapropel s1 deposition, and throughout the interruption a gradual cooling took place, leading to another warming phase during the subunit s1b. 5. discussion 5.1. paleotemperature estimates and difference between the two proxies our results show temperatures comparable to those reported during the sapropel s1 by kallel et al. (1997). in detail, in the investigated period, both proxies record comparable temperatures in terms of average values, however there are some dissimilarities at a smaller scale: in fact, whereas the isotopic temperature after a sharp increase at 10 cal ka bp does not show great fluctuations, paleotemperature reconstruction based on mg/ca ratios shows higher values in the interval from 10 to 8.8 cal ka bp and from 6.6 to 6.3 cal ka bp during the deposition of the two sub-units of sapropel s1, and lower values in the interval from 8.8 to 7.2 cal ka bp, with the lowest temperature recorded at 8.2 cal ka bp corresponding to the sapropel interruption (fig. 4). in detail, based on calculated isotopic temperatures, the sapropel s1 interval was characterized by a general increase in water temperatures at the surface and in the sub-surface layers, as clearly evidenced by g. ruber and g. bulloides, respectively. the mean temperature estimate for g. ruber (20°c) is consistent with the growth temperature proposed by kallel et al. (1997 and table 4 therein) for the same species during the sapropel s1 deposition in the ionian basin. the sapropel sst is also taken to be equivalent to the modern one in the ionian basin and the growth temperature of g. ruber is found to correspond to the mean sst of the summer mixed layer (manca et al., 2004). this datum further supports that, during the sapropel interval, the ssts in the ionian sea were similar to the present ones. the amplitude of the temperature changes recorded by g. ruber is broad, up to 8°c from the warmest to the coldest values and is consistent with paleotemperature variations documented in the same area during the sapropel s1 deposition by emeis et al. (2000). this broad amplitude is due to the very thin summer mixed layer really sensitive to any runoff event or heating anomaly which would have great impact as compared with other thicker water masses (gonzalez-mora et al., 2008). the variability of the g. bulloides data are even wider than those of g. ruber (around up to 10°c of difference between the coldest and the warmest samples), this although the general trends are similar. the mean temperature estimate for g. bulloides (12.7°c) is cooler by about 2°c respect to that of today. as g. bulloides is prolific at depths below the thermocline (pujol & vergnaudgrazzini, 1995), the observed difference in temperature estimate respect to g. ruber suggest the presence of a marked thermocline or an increasing summer thermal gradient. moreover, the large gradient between the temperatures recorded by g. ruber and g. bulloides can be interpreted as related to their seasonality (pujol & vergnaud-grazzini, 1995) suggesting that the two different water masses remained isolated at the seasonal scale, due to a permanent seasonal stratification. the mean temperature estimate, based on mg/ca ratios, for g. ruber is consistent with the isotopic temperature during s1a subunit (20°c) while is cooler by about 1.5°c during s1b subunit (18.6°c). discrepancies between temperature estimates from mg/ca ratios and calculated isotopic temperature may be ascribed to the different variables influencing the two proxies. the oxygen isotopic temperatures are based on biogenic δ18oforam which is affected by δ 18owater. the variability between the mg/ca and oxygen isotope temperature reconstructions of g. ruber may, in part, be explained by changes in δ18owater. in our reconstructions, we assumed a constant δ 18owater during the entire investigated interval, but it is fig. 3 down-core mg/ca ratios of g. ruber var. alba for core et99m11 across the sapropel s1. the grey areas, representing the extent of the two sub-units of the sapropel s1, are from vigliotti et al. (2011). bergami c. et al. 10 reasonable that during the sapropel deposition the well documented enhanced run-off and the subsequent different evaporation/precipitation budget, and the presence at the surface of freshwater-diluted lenses influenced this value. on the contrary, mg/ca ratios in modern planktonic foraminifera are assumed and have been demonstrated to be predominantly a function of the temperature of the water in which they grew, while salinity is a secondary factors that exert influences on shell mg content, but not in the mediterranean, where several authors (ferguson et al., 2008; sabbatini et al., 2011 and references therein) suggested that mg/ca ratios can be strongly affected by the high salinity values typical of this basin. in detail, measured mg/ca values of planktonic foraminifera, collected in the eastern and central mediterranean basins, correlate poorly with the calcification temperatures but more significantly with calcification salinities, demonstrating that the salinity can be a primarily influencing factor in these environments. however, during the sapropel deposition, surface water salinity decreased and became almost homogeneous over the whole mediterranean basin with an average value for the ionian sea of 35.2 psu (kallel et al., 1997 and table 4 therein), which is close to that of the western mediterranean basin (e.g. alboran sea) where the mg/ca ratios are not influenced by the salinity regime (ferguson et al., 2008). then it is reasonable that, during the sapropel deposition, the salinity did not exert influences on shell mg content, being the mg/ca ratios primarily influenced by sst variations. in addition, we may exclude the possibility that post-deposition process or the presence of a mg‐rich calcite coating influences the results, firstly because sapropel layers are really conservative environments often characterized by the lack of bioturbation and often apparently high sedimentation rates. secondarily, we observed in our samples, that the sapropel microfauna fig. 4 δ18o and mg/ca g. ruber var. alba inferred temperature records from core et99m11. the grey areas, representing the extent of the two sub-units of the sapropel s1, are from vigliotti et al. (2011). open symbols represent mg/ca data, overlain with a line representing a 200 year gaussian smoothing. the sapropel s1 in the ionian sea 11 association was typically characterized, as observed by other authors (capotondi et al., 1999; negri et al., 1999), by the occurrence of specimens showing a very thin test structure, easily observed at the optical microscope, which point to a very good test preservation with no or few secondary calcite overgrowth. concluding, our data show that fluctuations in the mg/ca ratios are more pronounced than in the isotopic values suggesting a promising tool for paleotemperature reconstruction also in the mediterranean, but only when the influence of salinity will be entirely clarified. 5.2. mediterranean connection with the north atlantic ocean climate changes during the holocene have been gathering increasing attention because of the occurrence of millennial‐scale abrupt climate changes, of possible hemispheric extent, during this period (e.g., bond et al., 2001; gupta et al., 2003; mayewski et al., 2004), when the boundary conditions such as co2 concentration and ice volume were relatively constant and similar to the present ones. in the north atlantic, ice‐rafted debris (ird) events exhibit a distinct pacing on millennial‐scale during the holocene (bond et al., 2001). recently, several authors identified the expression of these events also in the sedimentary record of the mediterranean sea (e.g. cacho et al., 2001; frigola et al., 2007; rouis-zargouni et al., 2010; incarbona et al., 2008; 2010; vallefuoco et al., 2011; capotondi & vigliotti, 1999). comparison of our record of δ18oforam with north atlantic holocene millennial scale climatic variability (bond et al., 1997) allowed to highlight several shortterm cold oscillation at around 10.7, 9.5, and 8.2 cal ka bp comparable with the events numbered 7, 6, and 5 by bond et al. (2001; 1997) (fig.2). this indicates a possible atmospheric connection between the central mediterranean and the north atlantic region and the strong relation between climate and oceanographic changes during the sapropel s1 interval. one of these climatic features has been already documented by several authors in other areas of the mediterranean sea (e.g. rohling et al., 1997; de rijk et al., 1999; sangiorgi et al., 2003; vigliotti et al., 2011; asioli et al 1999; ariztegui et al., 2000), and was related to the so-called “8.2 event” (alley et al., 1997) and the associated δ18o increase of greenland ice cores. based on the isotopic temperature signal, during the three events the magnitude of the sea surface cooling is comparable to that proposed by bond et al. (1997) in cores from the north atlantic ocean, and does not exceed 2°c. based on the mg/ca temperature reconstruction, the cooling exceeded 2°c only during the event centred at 8.2 cal ka bp with a decrease in temperature of at least 5°c corresponding to the shift also proposed by alley et al. (1997) during this event. then in the studied core the mg/ca method evidences very sharp short time fluctuations much less evident with the isotope paleotemperature method. then, our data suggest a strong sensitivity of the central mediterranean basin, during the sapropel s1 time interval, to changes occurred in the north atlantic and therefore supports the high low latitude climatic mediterranean interplay also evidenced in colleoni et al. (2012) for the plio-pleistocene time interval. 6. summary a high-resolution investigation on the holocene sapropel s1 in the ionian sea was performed based on planktonic foraminifera geochemical data (stable oxygen isotopes and mg/ca ratios) proxies. this study documents promising results of the mg/ca paleothermometry applied to planktonic species. the first phase of the sapropel s1 was characterized by higher temperature, also consistent with the modern ones in the eastern mediterranean basin, while the second phase registered cooler temperature by about 2°c. during the sapropel interval, several cooling episodes, time equivalent to the millennial climatic variability in the north atlantic, were recognized at 10.7, 9.5, and 8.2 ka bp, the latter corresponding to the well known “8.2 event” and synchronous to the sapropel interruption. the climatic oscillations recorded by our study suggest an hemispheric-scale atmospheric connection in the central mediterranean basin. acknowledgements part of this study was funded by the projects sinapsi and ricerca spontanea a tema libero (rstl n. 154; “sapropels s1 e s5: archivi della variabilità climatica indotta dal regime monsonico”). we thanks m. coltelli, p. del carlo and l. vezzoli to provide core et99m11. we also thank alessandra negri and an anonymous rewiever who greatly improved the manuscript with their comments. this is the ismar contribution 1784. references alley r. b., mayewski p. a., sowers t., stuiver m., taylor k. c., clark p. u. 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documenti pdf creati possono essere aperti con acrobat e adobe reader 5.0 e versioni successive.) /enu (use these settings to create adobe pdf documents suitable for reliable viewing and printing of business documents. created pdf documents can be opened with acrobat and adobe reader 5.0 and later.) >> >> setdistillerparams << /hwresolution [1200 1200] /pagesize [396.850 566.929] >> setpagedevice amq28(2)121-129 moscon rivisto 12_2015.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 28 (2), 2015, 121 129 very-high resolution analysis of a transgressive deposit in the northern adriatic sea (italy) giorgia moscon¹, annamaria correggiari², cristina stefani¹, alessandro fontana¹, alessandro remia² ¹dipartimento di geoscienze, università degli studi di padova, padova, italy ²istituto di scienze marine cnr, bologna, italy corresponding author: g. moscon <giorgia.moscon@studenti.unipd.it> abstract: the adriatic sea is characterized in the northern and central shelf by different generation of isolated transgressive bodies formed and drowned in-place during the last relative sea-level rise. the continental shelf is characterized by a low gradient and, within the transgressive deposits the episodic variations in sea level and sediment supply caused the formation of backstepping parasequences. the transgressive bodies have been studied in detail because they have considerable amount of sorted sand exploitable for beach nourishment. a transgressive deposit, located south of the po delta, offshore ravenna at depth of 34-35 m, has been investigated with a total coverage of very-high resolution (vhr) seismic profiles and high number of cores in order to understand the stratigraphic evolution during the late quaternary sea-level rise. the transgressive body is composed of four seismic units separated by high-amplitude and high continuity reflectors, corresponding to peat and organic-rich layers indicating different depositional phases. the core analysis confirmed the presence of different units showing sediment variation from clay with peat-layer at the base to fine-grained sand at the top of the deposit. furthermore, the core analysis gave information about the thickness of the deposit. the thickness of the transgressive body is from 3 to 5 m and each unit varies from 1 to 2 m. in particular, the sand portion reached a maximum thickness of 1.5 meters. the seismic analysis and the digital elevation model constructed for key surfaces highlighted the channel system direction was towards ene during last glacial maximum and during sedimentation of unit 1 and 2, while it shifted toward ese during the formation of unit 3. moreover, to constrain the chronology of the sedimentary evolution, some peat and organic-rich samples, have been dated with 14c method. these organic horizons are evident seismic reflectors and correspond to key surfaces. they are characterized by brackish lagoon facies and could be a proxy indicator for the relative paleo-sea level. along with the previous data, they indicated that the sedimentation of the studied transgressive body occurred around 10,000 cal. a bp. keywords: quaternary, sea-level rise, sequence stratigraphy, beach nourishment, chirp-sonar 1. introduction the late glacial and holocene (post 18,000 a) sealevel rise is well recorded in the adriatic sea due to the peculiar physiographic and sedimentary setting of the basin (correggiari et al., 1996). during the last sea-level rise the northern adriatic sea was characterized by the formation of different generation of barrier-lagoon systems. these bodies, drowned in-place and partly preserved, crop out in the northern adriatic seafloor as elongated build-ups parallel to the present coastline. they are interpreted as patches of ancient coastal wedges which have considerable amount of sorted sand and are a significant resource exploitable for beaches nourishment. the sand portion of the transgressive deposits has been studied in detail with grain-size analysis, petrographic analysis, sedimentary architecture and volumes calculation in order to use this resource for coastal nourishment. the detailed characterization of a transgressive deposit located south of the po delta, through very-high resolution seismic profiles and facies analysis can shed new lights on the formation and evolution of the transgressive deposits. in particular, as the formation of the transgressive bodies is strongly related to the changes of relative sea level, their multidisciplinary study can produce important data in the reconstruction of the past relative position of the sea level (antonioli et al., 2009) and detect centennial fluctuations. 2. geological setting 2.1. the adriatic sea the adriatic sea is an epicontinental semienclosed basin (fig. 1) surrounded by three thrust-andfold-belts: the ne-verging apennines, the s-verging southern alps and the sw-verging dinarides. the basin records the evolution from a passive margin, during the fig. 1 location of the study area in the adriatic sea. bathymetry and superficial geology modified from the geological map of italian seafloor (fabbri et al., 2001; trincardi et al., 2011 a, trincardi et al., 2011 b). mesozoic, to a foreland basin system, during the cenozoic (d’argenio & horvath, 1984; ori et al., 1986; ciabatti et al., 1987; argnani & frugoni, 1997). during quaternary sea-level fluctuations the basin has been shaped by huge change of the oceanographic regime and sedimentary dynamics (trincardi et al., 1994, 1996). during the last glacial maximum (lgm, 30,000-19,000 14c a bp; lambeck & purcel, 2005; clark et al., 2009) the sea-level was about 120-130 m lower than today and the northern continental shelf was completely in subaerial conditions (fig. 2a). in this environment several river networks formed, consisting of by a main trunk river (paleo po river) and alpine and apennines tributaries; the fluvial system terminated in a low-stand delta located at the northern edge of the meso-adriatic-depression, southeast of ancona (de marchi, 1922; correggiari et al., 1996; ridente & trincardi, 2005). during the late-glacial to early -holocene transgression, a glacio-eustatic, non-steady sea-level rise of approximately 120 meters caused substantial basin widening coupled by changes in energy regimes across the basin (cattaneo & steel, 2003) (fig. 2b). the low gradient of the northern adriatic shelf, together with the sea-level rise (approximately 10-15 mm/a), favoured the deposition and drowning of different generations of transgressive barrier-lagoon system sedimentary bodies. in contrast, the steeper topographic gradient of the southwestern adriatic shelf has been characterized by the deposition of thick transgressive progradational deposits (cattaneo & trincardi, 1999; maselli et al., 2011). the maximum marine ingression was reached ca. 5500 cal. a bp when the basin occupied much wider area than during the low-stand (fig. 2c). during highstand the anticlockwise circulation characterizing the adriatic caused southward transport of sediment along the entire western side of the basin as documented in surficial geology maps of the adriatic (fabbri et al., 2001; trincardi et al., 2011 a; trincardi et al., 2011 b) (fig. 1). our study focused on a transgressive deposit, located 50 km from ravenna at 34-35 m water 122 moscon g. et al. fig. 2 widening of the adriatic basin during the last transgressive cycle. (a) sea-level during the last glacial maximum (lgm), an extensive portion of the adriatic sea was in subaerial condition, while the meso-adriatic-depression (mad) was a semi-enclosed basin receiving high amount of sediment (correggiari et al., 1996). (b) rapid sea-level rising after the lgm. (c) maximum marine ingression reached 5500 cal. a bp. fig. 3 main cores facies description. (a) simplified log of most representative cores. the tst deposits rest on the transgressive surface. the paralic deposit is characterized at the base by clay sediment, peat and organic-rich layers and at the top by a sand portion. this deposit ends with ravinement surface. (b) example of cores facies. 1: peat layer; 2: interbedded clayey and silty layers; 3: sand portion; 4: ravinement surface (rs). depth (fig. 1). this transgressive deposit showed a dominant longshore trend parallel to the modern coastline, it extends ns for about 20 km and is 8 km wide. its thickness varies from 1 m near the boundary areas to 4 meters in the depocenters. 2.2. transgressive deposits the late-glacial and holocene transgressive deposits (transgressive system tract, tst) in the adriatic basin were formed by backstepping barrier-lagoon and incised valley systems in the low gradient northern shelf, while mud sedimentary bodies thicker than 25 m are present in the central adriatic shelf (cattaneo & trincardi, 1999; maselli et al., 2011, trincardi et al., 2013) (fig. 1). the tst rests on an erosive surface of regional extent (transgressive surface, ts) that truncates older low-stand deposits (lst), and is below the maximum flooding surface (mfs) (fig. 3). available 14c data show that the time interval encompassed by the tst spans about 11,000 years, between 16,000 and 5500 cal. a bp (correggiari et al., 1996; trincardi et al., 1996; cattaneo & trincardi, 1999, correggiari et al., 2001, maselli et al., 2011). the transgressive deposits in the northern adriatic shelf are located at sea bottom between -45 m to -10 m water depth, and they are preserved as elongated undulating elevations almost parallel to the present coastline. the complex geometry and their preservation is probably due to a combination of different factors such as the rate of sea-level rise, the low gradient of the shelf and the coastal dynamics (belknap & kraft, 1981, correggiari et al., 2011). in the northern adriatic sea, transgressive deposits are generally associated to a barrierlagoon system, that is typically characterized by clayeysilty lagoon deposits associated with sandy beach deposits (fabbri et al., 2001) (fig. 3). 3. methods the transgressive deposit has been examined with a multi-disciplinary approach through very high resolution (vhr) seismic profile analysis and vibrocorer samples, digital elevation model (dem) of most significant surfaces and 14c dating. all the analysed data have been collected during oceanographic cruises carried out in the last 20 years by cnr-ismar onboard urania r/ v. vhr seismic profiles have been acquired with sub bottom profiler chirp-sonar with 16 low-frequency transducers. about 750 km of vhr seismic profiles, oriented ns and spaced 120 meters each other, covered the transgressive deposit (fig. 4a). the seismic profiles have been processed and interpreted with seisprho (gasperini & stanghellini, 2009). cores have been collected by vibrocorer rossfelder p5, with a vibrating head and a steel corer 6-m long and 10-cm wide. dems of key seismic surfaces, obtained from conversion tools ascii to raster of arcmap 10.1 software, have been used to map their areal distribution. furthermore the top of the transgressive deposit, coinciding with the seafloor, has been analysed with the digital elevation model of the multibeam bathymetry (with image resolution of 10 m) acquired during the nad12 (in 2012) oceanographic cruise onboard urania r/v (fig. 4b). the device used is an em 710 multibeam echosounder with 70-100 khz. the geochronological constrains of the geological evolution have been provided by the 14c dating of 3 samples of organic-rich and peat layers, in the core ar00_22. the ams analysis has been done at the ion beam laboratory at the eth institute in zurich. our data have been integrated with those from core cm94_107 (fabbri et al., 2001). the radiocarbon ages from ar00_22 and cm94_107 cores have been calibrated using calib14 radiocarbon calibration program of stuiver & reimer (1993). the results have been corrected for isotopic fractionation, but no correction for oceanic reservoir was made because the dated layers are of terrestrial origin. 4. results 4.1. seismic analysis the seismic profiles analysed, were collected during the oceanographic cruises nad12. the detailed seismic-stratigraphic analysis highlighted three different seismic facies: 1) a semi-transparent unit, due to scarce penetration of the acoustic signal, indicative of sandy sediments, characterized by an irregular, erosive base; 2) an interbedded transparent seismic facies with parallel and subparallel irregular and discontinuous reflectors related to fine-grain deposits with thin fine sand or silty layers; 3) regular and continuous reflectors interpreted as peat and organic-rich layers. in each profile five key surfaces have been identified and traced in order to define the geometry of deposits and to investigate the formation and evolution of the transgressive parase 123 reconstruction of a transgressive deposit fig. 4 study area detail. (a) tracks of vhr seismic profiles, acquired in 2012, covering the study area. (b) seafloor bathymetry (image resolution of 10 m). evidence of the ese channel system trend. quences. the key surfaces, easily visible and traceable along the entire profile, correspond to organic rich and peat layers. the seismic reflector interpreted as transgressive surface marks a different response in the seismic profile and has been traced correlating the dated peat layers from published data (fabbri et al., 2001; correggiari et al., 2011). the ts is an erosional surfaces that marks the first major flood of the margin. it rests on the low-stand deposit formed during the lgm where the top was dated at 20,000-21,000 14c a bp by radiocarbon dating of peat samples southern than the investigated deposit by trincardi et al. (1994); fabbri et al. (2001); cattaneo & steel, (2003). the studied transgressive body rests on the ts. in addition to the ts other three key reflectors have been identified within the transgressive deposit (a surface, b surface, c surface and seafloor surface at the top, fig. 5); these surfaces border four different units (from unit 1 at the base, to unit 4 at the top) that mark four different depositional environments during the sedimentation of the transgressive deposit (fig. 5). moreover within the most recent unit an additional key surface has been identified at the base of the sandy portion. the unit 1, 2 and 3 were delimited by the digitized key surfaces, corresponding to peat layers, and were characterized by interbedded transparent and discontinuous seismic reflectors, which were more regular within the unit 3. at the top of both the unit 1 and the unit 2 seismic profiles revealed the presence of some channels bordered by levees. the unit 4, was delimitated at the base by the c key surface and at the top by the seafloor. additional key surface within unit 4 divided the base with irregular and discontinuous seismic reflectors and at the top a semitransparent seismic facies indicative of sandy sediments. 4.2. digital elevation models of key surfaces the digital elevation models showed the morphology of the surfaces highlighting the occurrence of the channel system network existing when each of them was exposed and active (fig. 6). thus, each dem represents one step in the formation of the transgressive deposit. the ts lies higher to the west and lower towards east, characterized by channels with ene direction (fig. 6a). at first, the sedimentation over the ts occurred in the north/northeast and western areas and shows an ene channel progradation. this situation was highlighted by the dem of the a surface (top of the unit 1) and the dem of the b surface (top of the unit 2) (fig. 6b/c), and then the sedimentation of the transgressive fig. 5 evidence of the key surfaces and units within the sedimentary transgressive body. 124 moscon g. et al. body shifted to the south/southwest. the dem of the c surface (top of the unit 3) highlighted the filling of the southern area together with the variation of the channel direction from ene to ese (fig. 6d). the transgressive body ended at the top with unit 4, that correspond to the basal clay lagoon layer resting on the c surface, filling and flattening the transgressive body. the seafloor bathymetry (fig. 4b), that coincides with the top of the unit 4, maintained the same ese channel trend as highlighted for unit 3. 4.3. cores facies analysis and calibration of seismic units 30 cores collected during the oceanographic cruises cm94 and ar00 (in 1994 and 2000) onboard urania r/v (cnr-ismar) have been described to define the depositional environment corresponding to the sedimentation of the transgressive body. the cores had a length spanning between 1.5-4 m and generally showed coarsening-upward trend with a thin finingupward layer at the top. the basal portion was formed by clay with some peat layers. this unit was overlain by fine-sand that was capped by an erosional surface. the tst deposit was covered with thin layer (about 15-30 cm) of silty-clay representing a recent distal po prodelta highstand deposit (correggiari et al., 2005; correggiari et al., 2011) (fig. 3). the unit 1 rests on the transgressive surface and is capped by the a surface (fig. 5), it was found only in the northern part of the investigated area and it is organized in elongated river systems that are elevated above the ts and oriented towards ene. these systems lie on the ancient fluvial system highlighted by the ts, and in the seismic profiles it was possible to recognise some leveed channel systems. the unit 1 was mainly formed by clay with organic matter and millimetric plant debris interbedded with peat layers (fig. 7), farther few cores highlighted a fine-sand to silty layer at the top of this unit. the fossil content belonging to this unit was characterized by the mollusc association consisting of cerastoderma glaucum, abra segmentum and lentidium. the unit 2 was bounded at the base by the a surface and at the top by the b surface (fig. 5), it was mainly present in the northern and western part of the investigated area and it filled the depressed zones formed between the unit 1 channel systems. this unit was similar to the unit 1, characterized by clay with organic matters and carbonaceous frustules, while the top was an easily recognizable layer of peat with a thickness of 10-15 cm (fig. 7). the fossil content was the same as of the unit 1. the unit 3 was bounded at the base by the b surface if present or by the ts surface where it was not present and at the top by the c surface (fig. 5). unit 125 125 reconstruction of a transgressive deposit fig. 6 dems with isopach of the key surfaces obtained from conversion tools ascii to raster of arcmap 10.1 program. comparison of dem. variation in channel system trend and preservation of each unit. the channels depicted in each surface have been traced in blue, while the dashed rivers represent the leveed channel systems elevated above the underlying surface. 3 was mostly developed in the southern part of the area, while in the northern sector was limited to a thin layer below the unit 4. the southern portion of the unit 3 was characterized by 2-2.5 meters of clay layers with millimetric plant debris interbedded with parallel-laminated silty layers (fig. 7). the northern portion of the unit 3 was formed of a thin layer of clay that filled and smoothed the underlying depressed areas. the paleontological association was characterized by cerastoderma glaucum, abra segmentum and lentidium sp. the unit 4 was bounded at the base by the c surface and at the top by the seafloor (fig. 5), its geometry showing two convex landforms with a gentle trough in the middle of the deposit. in this unit a significant amount of sorted sand has been found within the two build ups above a thin clayey layer. the sand portion, that reached up to 1.5 m of thickness, ended with a bioclastic sand layer representing the ravinement surface (rs) (fig. 7). the analysis on the sand below the rs showed a mean diameter between 0.25-0.35 mm and a very scarce content of silt and clay (correggiari et al., 2011). the top of the deposit is locally characterized by a very thin 15-30 cm layer of clay. 5. discussion the combined seismic and core analyses allow us to reconstruct the evolution of the transgressive deposit. the four units, forming the transgressive body, show different environment of sedimentation. the basal units (unit 1, unit 2 and unit 3), consisting of silty-clay sediment with organic matter and interbedded peat layers, are indicative of lower delta plain environments with distributary channels and lagoon. the paleontological content, recognized in clay layers belonging to unit1, 2 and 3, is indicative of euryhaline association of bivalves peculiar of transitional environment from fresh to brackish water. the more recent unit (unit 4) consists of basal thin layer of clays formed in a lagoon environment, covered by two plano-convex bodies of basal beach sand. this unit represents a patch of barrier-lagoon system capped by the ravinement surface formed by bioclastic sand. the combined study of seismic profiles and cores emphasizes a marked difference between the basal and the superficial portion of the deposit in terms of sedimentary environment and preservation potential. the buried units, belonging to an inner coastal environment 126 moscon g. et al. fig. 7 ar00_22 core log plotted on nad216 seismic profile, location in fig. 5 . on the left, the picture shows the position of ar00_22 in the seismic profile, the seismic units in color bordered by the key surfaces. on the right, the picture shows the description of the ar00_22 core, their core facies, highlighted by the photos, corresponding to the white panels a, b, c, d close to the core log. compared to the unit 4, indicate back-barrier environment. the analysis of the seismic profiles highlighted a local aggradation of the unit 1, 2 and 3 that filled the morphological depressions inherited from of the previous topography. on the contrary, unit 4, which was strongly affected by marine processes, was characterized by erosion and reworked sediment, as highlighted by the ravinement surface. the comparison among dems of the surfaces confirmed limited erosion in units 1, 2 and 3, while marked reworking occurred at the top of unit 4. the buried units were characterized by erosion due to the activity of washover fans or fluvial floods, while unit 4 was subjected to shallow marine processes such as wave activity. moreover, the seafloor dem, which shows the present bathymetry, highlights that the path of channels is in relief. this setting suggests differential erosion within unit 4 with the removal of softer or less stiff sediment. 127 reconstruction of a transgressive deposit tab. 1 radiocarbon and calibrated dating from cm94_107 (fabbri et al. 2001) and ar00_22 cores. fig. 8 a: depth vs. age plot. in blue are represented the adriatic 14c data from composite table in antonioli et al. (2009) and from geological map of the italian sea (fabbri et al., 2001; trincardi et al., 2011 a-b). in orange are represented the radiocarbon dating from this work. in grey are represented th/u data from fairbanks (1992) and bard (2003). b: simplified scheme of the transgressive deposit with water depth and age of each unit. the radiocarbon data constrains the time of sedimentation of the transgressive deposit between 11,000 to 9800 cal. a bp, in the time interval following the melt waters pulse 1b (fairbanks, 1989). this was characterized by both the strong influx of freshwater and the increased sediment loads by rivers, especially the po (ariztegui et al., 2000). the dating samples (tab. 1) gave information about the rate of sedimentation in each unit. the unit 1 (thickness up to 1 meter) was deposited in about 500 years, the unit 2 (thickness up to 2 meters) in about 300-500 years, while the unit 3 (thickness up to 1 meters) was deposited in about 200 years. the obtained data were plotted in a depth vs. age plot which groups adriatic 14c age data from fabbri et al. (2001), antonioli et al. (2009) and trincardi et al. (2011 a-b) (fig. 8). the new data coincide with the published curves showing in particular 1110 years gap between the base of the unit 1 and the c surface. considering an average thickness of about 4 meters, the estimated, relative sea-level rise was about 0.4 cm/a. moreover the detailed study of this transgressive deposit showed that the variation of the channel system trend from ene to ese, coincides with the incipient sea-level rise. 6. conclusions the vhr seismic profiles, acquired in the northern adriatic shelf during the nad12 oceanographic cruise, supported key information to characterize in detail the transgressive deposit located offshore ravenna at depth of 34-35 m. the combined study of vhr seismic data and cores gave new information about the sedimentation, evolution and age of the deposit. the transgressive deposit consists of four units, each one of them representing an evolutionary step. the lower units (unit 1, unit 2 and unit 3) correspond to delta plain setting with some distributary channels and a lagoon, while the upper unit (unit 4) represents a barrier-lagoon system with patches of ancient beach at the top. the sedimentation of the transgressive deposit occurred between 11,000 to 9800 cal. a bp. in particular the radiocarbon data allowed to estimate the rate of relative sea-level rise and sedimentation rate of each unit. moreover, the dated layers correspond to peat or organic-rich horizons of brackish lagoon facies, thus, they are representative of the paleo-sea level and mark the aggradation steps of each unit. the variation of the channel system trend from ene to ese occurred during the sea-level rise and it brought to the change of the coastal paleogeography. at the beginning the coast was growing eastward, then the basin flooding (recorded by the unit 3 at 35 m water depth) caused a preliminary drowning of the investigated area and a consequent variation of the channel system trend. the detailed study of this transgressive body shows not only its evolution but also the paleogeography variation of the surrounding areas due to both sea-level rise and the fluvial pattern. acknowledgements this work is part of a phd project in partnership between geoscience department of padova and marine science institute of bologna. we thank the ismar-cnr of bologna that have made available all the cores and vhr seismic profiles acquired during cm94, ar00 and nad12 oceanographic cruises. the research has been partially founded by the italian ministry of education, universities and research miur, within the project ritmare “the italian research for the sea” (belonging to the national research program 2012-2016 and coordinated by the italian national research council-cnr) and through a contract from emilia-romagna region (servizio geologico, sismico e dei suoli). we thank the eth institute for the ams analysis. we thank captain, the crew and all the researches on board r/v urania (cnr) that acquired seismic profiles and cores. this work has been partly supported by the university of padova: cristina stefani and giorgia moscon by institutional found, and by the project: “sea-level variations and subsidence in northern adriatic in the last 130,000 years through geomorphological, stratigraphic and geoarchaeological indicators”, funded by the university of padova (cod. c91j10000320001, supervisot :dr. a. fontana). we thank the two reviewers that allowed to improve the paper. this is cnr ismar -bologna contribution no. 1870 references antonioli f., amorosi a., fontana a., bondesan a., braitenberg c., dutton a., ferranti l., fontolan g., furlani s., lambeck k., mastronuzzi g., monaco c., orrù p. 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(2013) bathymetry of the adriatic sea: the legacy of the last eustatic cycle and the impact of modern sediment dispersal. journal of maps, 10 (1), 151-158. 129 reconstruction of a transgressive deposit ms. received: may 18, 2015 final text received: july 9, 2015 impaginatosanto ecc... ppeerriiccoolloossiittàà ccoonnnneessssaa aa pprroocceessssii aalllluuvviioonnaallii iinn aarreeee ppeeddeemmoonnttaannee:: iill ccaassoo ddii ccaasstteellllaammaarree ddii ssttaabbiiaa iinn ppeenniissoollaa ssoorrrreennttiinnaa aa.. ssaannttoo11,, nn.. ssaannttaannggeelloo22,, aa.. bbeenneedduuccee33 && ff.. iioovvaannee33 1sezione di geologia applicata del dipartimento di ingegneria geotecnica dell’università di napoli federico ii 2dipartimento di scienze della terra dell’università di napoli federico ii 3geologo collaboratore esterno riassunto e’ stato effettuato uno studio sulla pericolosità connessa a processi alluvionali di un’area campione della penisola sorrentina dove esistono importanti centri urbani in parte sviluppati su conoidi attive. il settore in oggetto (castellammare di stabia) presenta condizioni geologico-geomorfologiche simili a quelle di molti altri territori comunali della penisola sorrentina – monti lattari e di altri settori pedemontani campani, prestandosi così come area “campione” per lo studio delle condizioni di pericolosità legata a processi alluvionali in bacini torrentizi. l’analisi stratigrafica, geomorfologica e storica, ha consentito l’individuazione di numerosi eventi alluvionali recenti, che hanno interessato questo settore della penisola sorrentina dalla fine del settecento ad oggi. lo studio della documentazione recuperata ha permesso di localizzare e distinguere i danni relativi ai singoli eventi, e talvolta di riconoscere le varie tipologie dei dissesti; è stata così redatta una carta dei danni in cui sono evidenziate le aree colpite da uno o più eventi alluvionali, nel periodo che va dal 1764 al 1987, valutando anche l’evoluzione urbanistica dell’area , tramite l’utilizzo di cartografie coeve degli eventi alluvionali studiati. in termini di precipitazioni giornaliere questi eventi non hanno avuto carattere di eccezionalità in quanto episodi temporaleschi della stessa intensità si sono ripetuti più volte sul territorio, senza effetti degni di rilievo. la particolarità di queste precipitazioni va ricercata nella loro concentrazione oraria, che purtroppo non può essere quantizzata a causa della mancanza di dati pluviometrici, ma comunque confermata dalle precise descrizioni citate nella ricerca storica. in generale, i dati raccolti hanno evidenziato le condizioni di alta pericolosità geomorfologica per processi alluvionali; in questi contesti l’individuazione e lo studio delle conoidi attive, accompagnati da una accurata ricerca storica, possono contribuire, in modo significativo, alla definizione delle situazioni di maggiore pericolosità e rischio. abstract a study of the geomorphological hazard due to alluvial processes in a sample area of surrentine peninsula was carried out. this was done by the reconstruction of the short term geomorphological evolution analysis, by collection of historical data and by reconstruction of urban development. although the selected area is quite small, its geomorhological, topographical and urban features are very similar to those of other zones of campania region; in fact some portions of the urban area are built on holocenic alluvial fans systems. for these reasons, it can be considered a representative ”sample area” in which the geomorphological hazard conditions due to alluvial processes in piedmont areas can be outlined. the studied area is located in the piedmont area of lattari mounts which is characterized by the presence of coalescent and entrenched alluvial fans systems. the oldest fans system are middle pleistocene in age while the youngest are holocene and have been active till historical times. this paper focuses its attention to the definition of hazard conditions of the youngest generation of fans. the collection of historical data evidenced that several alluvial events have taken place in this sector of surrentine peninsula since the end of 18th century. the reports are so detailed that it was possible to locate the damage for each event and in some cases to recognise the kind of damage; a “damage map” showing the zones affected by one or more alluvial events from 1764 to 1987 was thus produced. as the location of the damage of each alluvial event was based on historical topographic maps (1812, 1875, 1909, 1954 and 1990), the damage map also takes in account the urban development. a morphometrical analysis of the hydrographic basins feeding the fans has been also carried out in order to define their concentration time; basin area and media gradient, river length and media gradient, basin maximum , minor and media altitude have thus been calculated on a topographic map (1: 5.000 scale). although we do not have data on hourly precipitation, the minute description of historical reports allowed us to hypothesize that the studied alluvial events occurred in coincidence with isolated precipitation peaks concentrated in few hours. the study thus evidences the high geomorhological hazard and risk conditions due to alluvial processes of the castellammare urban area. unfortunately, the results obtained may concern many other urban areas of surrentine peninsula with similar geomorhological, topographical and urban conditions. in these contexts the individuation of active fans together with a detailed historical research can strongly contribute to a better definition of the areas of highest hazard and risk. parole chiave: pericolosità geomorfologica; ricerca storica, conoidi alluvionali attive; olocene; appennino meridionale key-words: geomorphologic hazard; historical research; active alluvial fans; holocene; southern apennines il quaternario italian journal of quaternary sciences 1155(1), 2002, 23-37 11.. pprreemmeessssaa la pericolosità geomorfologica viene definita come la probabilità che un evento alluvionale o franoso di determinato tipo o magnitudo, si verifichi in un determinato intervallo di tempo e in una certa area; essa, a differenza di altre pericolosità geologiche come quella vulcanica e sismica che risultano ineluttabili, è talvolta dovuta ad errati interventi dell’uomo sul territorio. in penisola sorrentina gli eventi che possono determinare situazioni di pericolosità geomorfologica sono riconducibili alle seguenti tipologie: 1) ffrraannee nneellllee ccoollttrrii ppiirrooccllaassttiicchhee (montella, 1841; ranieri 1841; lazzari, 1954; penta et al., 1954; civita & lucini, 1968; de riso & nota d’elogio, 1973; guida et al., 1974; 1986; civita et al., 1975; celico et al., 1986; guadagno, 1991; vallario, 1992; giasi et al., 1996; calcaterra et al, 1997; celico & guadagno, 1998; del prete & mele, 1999; guadagno et al., 1998; di crescenzo & santo, 1999; de riso et al., 1999; 2) ffrraannee iinn rroocccciiaa (civita et al., 1975; guida et al., 1986; de riso, 1992; budetta et al., 1991; 1994; budetta & santo 1993; santo & tuccimei, 1997; 3) ffrraannee iinn tteerrrreennii ffllyysscciiooiiddii (cotecchia & melidoro, 1966; civita et al., 1975; travaglini & valdinucci, 1964), 4) aalllluuvviioonnii: lazzari 1954; penta et al., 1954; vallario, 2001). mentre nei primi tre casi la letteratura fornisce una ricca casistica, nel quarto caso (alluvioni) emerge una lacuna soprattutto per quanto riguarda la segnalazione di danni legati a fenomeni di trasporto solido per alluvionamento. se escludiamo gli eventi di particolare intensità come quelli che hanno interessato il salernitano nel 1924 e nel 1954 (lazzari, 1954), i vari lavori non si soffermano su queste fenomenologie. la ricerca storica dimostra invece che l’area della penisola sorrentinamonti lattari è stata più volte interessata da fenomeni di trasporto-accumulo di natura detritico-fangosa verificatisi in occasione di eventi piovosi particolarmente intensi che, come approfondiremo in seguito, hanno provocato ingenti danni e, in alcuni casi, la perdita di vite umane. questa nota si propone di evidenziare la pericolosità geomorfologica connessa a processi alluvionali in aree pedemontane, attraverso la ricostruzione dell’evoluzione morfologica di breve termine, la ricostruzione storica degli eventi e l’analisi delle modificazioni antropiche subite dal territorio. l’area di studio (castellammare di stabia) presenta condizioni geologico-geomorfologiche simili a quelle di molti altri centri urbani della campania (penisola sorrentina-monti lattari, costiera amalfitana, monti di nocera e cava dei tirreni, monti di avella, monti picentini) ubicati in settori pedemontani, alimentati da bacini idrografici con elevata energia di rilievo ed impostati su rilievi calcarei ricoperti da una coltre di piroclastiti sciolte. per tale motivo essa si presta come area “campione” relativamente alla definizione delle condizioni di pericolosità legate a processi alluvionali in questi contesti ambientali. 22.. iinnqquuaaddrraammeennttoo ggeeoollooggiiccoo ee ggeeoommoorrffoollooggiiccoo ddeellllaa ppeenniissoollaa ssoorrrreennttiinnaa la dorsale della penisola sorrentina è costituita da rocce carbonatiche (calcareo-dolomitiche) d’età compresa tra il trias superiore ed il miocene, cui segue verso l’alto un complesso arenaceo-argilloso; nel suo insieme questa successione è ascritta all’unità stratigrafico strutturale monti picentinimonti lattari (bonardi et al., 1988). su tutti questi termini si rinvengono terreni quaternari d’origine ed età diversa: brecce calcaree antiche, depositi alluvionali, materiali piroclastici, detriti di falda, alluvioni recenti, depositi di spiaggia, detriti di frana. l’area oggetto di studio è situata nel settore settentrionale della penisola sorrentina (fig.1) e rientra prevalentemente nei territori comunali di gragnano e di castellammare di stabia estendendosi tra il torrente gragnano (a nord) ed il torrente dello scurolillo (a sud). 24 a. santo et al. fig. 1 carta delle coperture piroclastiche dell'area di studio con indicazione dei bacini idrografici pyroclastic covers map with location of main drainage basins. la città di castellammare di stabia si sviluppa su un territorio pedemontano caratterizzato da una serie di conoidi incastrate che si estendono dalla base dei monti lattari fino al mare, testimoniando un’intensa attività alluvionale succedutasi nel tempo. in quest’area (fig.2) sono presenti almeno tre generazioni di conoidi alluvionali (cinque et al., 1987; cinque, 1991; aucelli et al, 1996), la più antica delle quali risale al pleistocene medio. essa è caratterizzata dall’assenza di materiali piroclastici e risulta costituita da ciottoli calcarei leggermente arrotondati ed eterometrici, con cemento calcitico che talvolta non riempie completamente i vuoti, conferendo alla roccia un aspetto vacuolare. le conoidi appena citate si conservano in alcuni lembi isolati e terrazzati (vallone del rivo san marco, sella di pimonte e foce del rivo scurolillo a pozzano) . le conoidi di seconda generazione sono incastrate nelle valli che dissecano le conoidi del pleistocene medio e sono caratterizzate dalla diffusa presenza di intercalazioni di materiale vulcanico, sia in posto sia rimaneggiato (fig.3). nella serie è intercalata, in giacitura primaria, l’ignimbrite campana (cinque et al., 1987) che, in altre località, è stata datata radiometricamente a 37.000 25pericolosità connessa a processi alluvionali ... fig. 2 schema geologico-geomorfologico dell’area studiata. da cinque (1991), ridisegnato. 1) calcari; 2) conoidi alluvionali di i generazione (pleist. medio); 3) conoidi alluvionali di ii generazione (pleistocene sup.); 4) conoidi alluvionali di iii generazione (olocene); 5) cordone dunare di bottaro-pioppaino (3600-2500 anni bp); 6) cordoni dunari di età storica; 7) paleofalesia versiliana; 8) piana alluvionale del f. sarno; 9) sondaggio; 10) traccia di sezione. geological and geomorphological sketch of the studied area. from cinque (1991), modified. 1) limestones; 2) alluvial fan deposits (middle pleistocene); 3) alluvial fan deposits (upper pleistocene ne); 4) alluvial fan deposits (holocene); 5) dune ridge of bottaropioppaino (3600-2500 yr bp); 6) dune ridges of historical age ; 7) paleo-seacliff (versilian); 8) sarno river alluvial plain; 9) borehole; 10) geological cross section fig. 3 stratigrafia della conoide di ii generazione (rivo foiano): 1) suolo; 2) ghiaie calcaree in matrice sabbiosa piroclastica; 3) livello di pomici bianche (diam. fino a 5 cm); 4) sabbia vulcanica grigia con pomici e scorie; 5) livello di pomici grigie (diam. fino a 5 cm; 6) ghiaie calcaree in matrice sabbiosa piroclastica.; 7) livello di pomici bianche (diam. pochi mm), gradate passanti ad una cenere compatta di colore grigio scuro; 8) deposito massivo costituito da una sabbia vulcanica inglobante clasti calcarei; 9) sabbie vulcaniche fini di colore grigio chiaro. stratigraphy of the middle pleistocene alluvial fan deposits: 1) soil; 2) calcareous gravels with sandy pyroclastic matrix; 3) white pumiceous level (diam. max. 5cm.); 4) grey volcanic sand with pumices and scories; 5) grey pumiceous level (diam. max. 5cm.); 6) ) calcareous gravels with sandy pyroclastic matrix;7) white pumiceous level (diam. max. 2mm.) evolving to a grey ash level; 8) massive volcanic sand with calcareous pebbles; 9) light grey, fine-grained volcanic sands. anni bp (deino et al., 1994); ciò consente l’attribuzione di questa fase alluvionale al pleistocene superiore. tra la fine del pleistocene superiore e l’olocene, le conoidi appena descritte subiscono un’intensa fase d’erosione lineare, cui fa seguito l'innalzamento del livello del mare riconducibile alla trasgressione versiliana, testimoniata da una paleofalesia che tronca le conoidi della seconda generazione, raggiungendo in alcuni punti l’altezza di circa 40 metri (cinque, 1991). la terza generazione di conoidi (conoidi di muscariello, sommuzzariello e quisisana; cinque, 1991) si presenta incastrata in quella del pleistocene superiore, è costituita prevalentemente da piroclastiti rimaneggiate e si sviluppa arealmente dalla falesia versiliana fino all’attuale linea di riva. i suoi prodotti, con particolare riferimento alla conoide del rivo san marco, ricoprono l’antico cordone dunare di bottaro-pioppaino, costituito da sabbie eoliche sovrapposte a depositi di spiaggia, che datazioni assolute e dati di sondaggio hanno fatto risalire a 3600 bp (barra et al., 1989). tali elementi hanno dunque permesso di datare indirettamente quest’ultima generazione di conoidi, attribuendole un’età storica e protostorica (cinque, 1991). per quanto riguarda la linea di riva, dopo la trasgressione versiliana, questa ha subito un graduale avanzamento, di circa tre chilometri, fino ad arrivare alla posizione attuale (cinque 1991); gran parte di questa progradazione è riconducibile, all'attività deposizionale che ha generato le conoidi di iii generazione e successivamente agli apporti piroclastici dell’eruzione vesuviana del 79 d.c. (sigurdsson et al., 1982). in particolare, quest’eruzione ha portato profonde modificazioni su tutto il territorio; infatti, oltre a causare la distruzione delle città di stabia, ercolano e pompei, ha ricoperto vaste porzioni dei versanti calcarei con più di un metro di pomici e lapilli, condizionando l’evoluzione geomorfologica di tutta l’area. 33.. ii ddeeppoossiittii rreecceennttii ccoorrrreellaabbiillii aa pprroocceessssii aalllluuvviioonnaallii eedd ii ddeeppoossiittii ppiirrooccllaassttiiccii oolloocceenniiccii il rilevamento geologico dell’area di studio è stato mirato prevalentemente ai depositi quaternari recenti delle conoidi di terza generazione e ai depositi piroclastici di età olocenica. depositi delle conoidi di terza generazione i depositi in oggetto sono quasi completamente ricoperti dall’abitato di castellammare di stabia e risultano affioranti solo nella parte apicale delle conoidi, in corrispondenza di alcuni terrazzi localizzati all'interno dei valloni che dissecano la generazione più antica. in particolare, all'interno dei rivi cannitello, san pietro e scurolillo sono state rilevate superfici terrazzate con estensione di alcune migliaia di m2 e con altezze fino a 10 m rispetto al fondo dell'incisione torrentizia. dall’osservazione diretta dei depositi è emerso che questi sono costituiti da ghiaie calcaree fortemente eterometriche, in abbondante matrice sabbioso-limosa di colore marrone e di natura vulcanica, ma soprattutto sono stati rinvenuti più volte, immersi nella matrice piroclastica, cocci di terracotta che sono una ulteriore prova dell’età storica delle conoidi di terza generazione. nella zona urbana, dove non sono osservabili tagli significativi, sono stati raccolti i dati di sondaggi che hanno evidenziato ripetute fasi di alluvionamento, testimoniate dalla presenza da ghiaie calcaree in matrice piroclastica alternate a depositi piroclastici rimaneggiati. questa sequenza, riconducibile alla terza generazione di conoide, ha uno spessore di circa 15 m (vedi stratigrafia del sondaggio in fig. 4) e poggia (fig. 5) su di un 26 a. santo et al. fig. 4 stratigrafia da un sondaggio del comune di castellammare di stabia (reinterpretato); 1) materiale di riporto; 2) alluvioni ghiaioso-sabbiose; 3) sabbie vulcaniche grigiastre; 4) alluvioni sabbioso-ghiaiose; 5) pozzolane rimaneggiate; 6) tufo di colore giallastro; 7) sabbia grigiastra con abbondanti fibre vegetali; 8) pomici di colore bianco-giallastro; 9) sabbie grigiastre con abbondanti frammenti di conchiglie. stratigraphy from a selected borehole. 1) reworked material; 2) alluvial gravels and sands; 3) grey volcanic sands; 4) alluvial sands and gravels; 5) reworked pumiceous levels; 6) yellow tuff deposits; 7) grey sand rich of vegetal materials; 8) white-yellow pumiceous level; 9) grey sands rich of fragments of shells. 27pericolosità connessa a processi alluvionali ... livello di sabbie ed argille di ambiente transizionale e litorale che, come già evidenziato da cinque (1991), può essere correlato al cordone litorale bottaropioppaino datato 3600 anni bp. quest'ultimo elemento stratigrafico consente di confermare l’età storica di questa generazione alluvionale, testimoniando un'intensa e "recente" attività torrentizia con tassi di sedimentazione molto alti (circa 5mm/a negli ultimi 3000 anni) che è stata ulteriormente documentata con i dati della ricerca storica. coperture piroclastiche l’area oggetto di studio si presenta in gran parte ricoperta da una coltre di terreni piroclastici cineriticopomicei da caduta, spesso humificati e con spessori variabili, riconducibili prevalentemente all’eruzione vesuviana del 79 d.c. che distrusse ercolano, stabia e pompei e che ebbe un asse di dispersione dei prodotti vulcanici orientato verso se (rolandi, 1997). la presenza di questo manto piroclastico, relativamente impermeabile rispetto ai calcari, condiziona il rapporto infiltrazione-deflusso dei bacini idrografici che drenano l’area di studio e costituisce la maggiore fonte di materiale per il trasporto solido. al fine di valutare le reali caratteristiche di permeabilità dei terreni affioranti e di stimare gli areali di affioramento ed i volumi del materiale piroclastico presente sui versanti dei bacini idrografici, è stata redatta una carta delle coperture che illustra la distribuzione e gli spessori dei prodotti piroclastici (fig.1) dalla carta delle coperture si evince che nonostante i prodotti vulcanici siano stati storicamente rimobilizzati attraverso ripetute fasi di erosione e frane, sui versanti è ancora presente una notevole coltre di piroclastiti e di suolo ad esse associato. solo circa il 10 % dell’area di studio (tab.1) presenta calcari affioranti e sub affioranti, la restante parte è ricoperta da piroclastiti e suolo di natura sabbioso-limosa. esse, oltre a condizionare la franosità (di crescenzo & santo 1999), contribuiscono ad aumentare gli effetti del ruscellamento superficiale e quindi del trasporto solido nelle zone pedemontane. 44.. mmoorrffoommeettrriiaa ddeeii bbaacciinnii iiddrrooggrraaffiiccii ee ccaallccoolloo ddeeii tteemmppii ddii ccoorrrriivvaazziioonnee il territorio di castellammare di stabia (figg.1-2) è attraversato da numerosi corsi d'acqua (rivo san marco, cannetiello, san pietro, cognuolo, piazza grande, foiano e scurolillo) che scendono dai monti lattari e sfociano lungo il litorale stabiese e sono caratterizzati da un marcato regime torrentizio. la parte alta del bacino idrografico di questi torrenti è impostata sulla successione calcareo-dolomitica ricoperta dalla coltre piroclastica, mentre nei tratti più a valle incide i depositi di conoide alluvionale. per ogni bacino sono stati calcolati (tab.1) i principali parametri fisici e morfometrici utili per la determinazione del tempo di corrivazione: superficie, lunghezze delle aste principali, gradiente di pendio del collettore principale, quota massima, quota minima, quota media. lo studio delle caratteristiche morfometriche è stato condotto su carte topografiche 1/5.000. esso ha interessato bacini d'estensione variabile dai 35 km2 del san marco a meno di 1 km2 per i bacini minori, questi ultimi caratterizzati anche da un ordine gerarchico estremamente basso. per quanto riguarda la pendenza media, essa oscilla tra valori di 40 e il 50 % ad eccezione dei rivi maggiori (san marco, cannetiello, e san pietro) che presentano valori più bassi risentendo dei lunghi tratti pedemontani a bassa pendenza. in tab.1 sono stati inoltre riportati, per i singoli bacini, gli areali di affioramento del substrato calcareo. come si può notare, questi areali superano solo alcune volte il 10%. questo dato risulta importante se si tiene conto che in termini di coefficiente di infiltrazione potenfig. 5 sezione geologica mostrante i rapporti fra le diverse generazioni di conoidi: 1) depositi di spiaggia attuali; 2) depositi di conoide di iii generazione (età storica); 3) depositi transizionali e litorali (olocene); 4) depositi di conoide di ii generazione (pleistocene sup.); 5) depositi di conoide di i generazione (pleistocene medio); 6) calcari (cretacico sup.); 7) sondaggio; 8) faglia. geological cross-section showing the relationships between the different generations of alluvial fan deposits. 1) present day beach deposits; 2) alluvial fan deposits (third order, historical age); 3) littoral and transitional deposits (holocene); 4) alluvial fan deposits (second order, upper pleistocene.); 5) alluvial fan deposits (first order, middle pleistocene); 6) limestones; 7) borehole; 8) fault. 28 a. santo et al. ziale, e quindi in termini di rapporto infiltrazione/deflusso, si passa dai valori dei calcari pari al 100% a quelli delle piroclastiti che sono pari al 50% (celico, 1988). valori che verosimilmente, possono ancora ridursi in condizioni di intense precipitazioni orarie. in generale, quindi, in risposta alle precipitazioni, il ruscellamento superficiale risulta elevato perché i bacini sono in gran parte impostati sulla copertura piroclastica. per quanto riguarda i tempi di corrivazione (tab. 2), essi sono stati calcolati adottando quattro diverse formule (tropeano et al., 1996). dalla tabella si può evincere che i valori dei tempi di corrivazione sono in generale molto brevi, come d’altra parte risulta ovvio per le limitate dimensioni dei bacini e per gli elevati gradienti che li caratterizzano. questo dato, importante, evidenzia la “rapidità” dei potenziali eventi, che si traduce in una limitata possibilità di allertamento ed evacuazione della popolazione e che incide notevolmente sulle condizioni di rischio di questi bacini. 55.. rriicceerrccaa ssttoorriiccaa ssuullllee aalllluuvviioonnii cchhee hhaannnnoo ccoollppiittoo ccaasstteellllaammmmaarree ddii ssttaabbiiaa l’indagine storica è stata condotta attraverso la consultazione di una rilevante quantità di documenti rinvenuti presso l’archivio storico e la biblioteca comunale; l’archivio storico della curia di castellammare di stabia e le emeroteche tucci e dell’università di napoli federico ii. essa ha portato alla luce preziosi documenti ed ha permesso di ricostruire e localizzare numerosi eventi alluvionali dei quali si era persa la memoria, nonchè di quantificare i diversi tipi di danni. gli eventi ricostruiti ed i relativi danni sono indicati in tab.3. di seguito verranno riportate solo alcune delle testimonianze storiche che, attraverso descrizioni puntuali, riescono a far capire quanto sia elevata la pericolosità geomorfologica in quest’area. eevveennttoo ddeell 11771155 in de rosa (1935) si legge: “un tratto della via che conduce al santuario di pozzano è attraversato dal torrente rivo del soccorso (rivo foiano) sul quale era un mal fermo ponte in legno che nel 1715 fu distrutto da una forte piena del rivo, sicché il transito ne rimase interrotto. i frati minimi, a proprie spese fecero ricostruire il ponte in muratura, su disegno dell’ing. g. lucchese. questo ponte esiste tuttora e dal 1715 ha resistito e resiste alle continue, violente e pericolose piene del rivo.” eevveennttoo ddeell 2200 ggeennnnaaiioo 11776644 nel verbale di una sessione capitolare, tenuta il 4 febbraio 1764, si narra che nella notte del 20 gennaio di detto anno, giorno seguente alla festività del santo protettore e vescovo catello, si scatenò, verso la mezzanotte, una terribile tempesta. dai monti vicini si rovesciò sulla città una grande quantità di acqua, che attraverso il rivo san pietro si riversò per le strade de turris, coppola, gesù e le altre vicine. ostruiti gli sbocchi al mare dai materiali trasportati dai torrenti, le acque salirono fino al secondo piano delle abitazioni. nel citato verbale si legge: “dai monti vicini cadde prolissa copia di acque sulla desolata città e con essa gran quantità di legnami svelti dalle radici nelle circostanti selve e come pure grandissima abbondanza di terreni, d’arena, d’argilla, di pietre e di macigni di grosso e grave diametro, che dopo tal terribile circostanza, si dovettero rompere adoperandosi le mine di polvere per ridurli a uso di fabbriche o di calcina.” una cronaca dettagliata del notaio vincenzo d’aiello conferma quanto già scritto e aggiunge altri particolari sull’accaduto. nel suo racconto si legge: “nelli paesi convicini vi sono morti una quantità di persone come gragnano, san ciro ed altri. in gragnano la parte di basso del trivione sono morte da cento e più persone affogate dalle acque ed oppressa dalle pietre delle proprie abitazioni cascateli addosso, portata via dall’acqua, e finora 20 del corrente ad ora 23 se ne sono ritrovate dei cadaveri dispersi per la campagna al numero 40.” a tal proposito, bisogna citare la relazione dell’architetto camillo ranieri, il quale nella pubblicazione del 1841 ricorda l’evento che colpì gragnano nel 1764, descrivendolo come una serie di scoscendimenti verificatisi tab 1 parametri morfometrici principali dei bacini analizzati; le superfici dei bacini sono calcolate sino alla sezione di chiusura. main morphometric parameters of the analysed drainage basins; the areas of the basin are calculated at the closing section. tab. 2 -tempi di corrivazione dei bacini studiati. per le sigle vedi tab.1. concentration times of the studied basin . for abbreviations see tab.1. bbaacciinnoo ss ss..ss.. ii ll hhmmaaxx hhmm hhoo ssccuurroolliilllloo 1,49 0.21 (14.3%) 39 2,5 1100 696 10 ffooiiaannoo 0,7 0.051 (7.3%) 49 1,4 820 503 15 pp.. ggrraannddee 0,38 0.038 (10%) 53 1 700 284 25 ccooggnnuuoolloo 0,6 0.07 (11.6%) 44 2,1 1050 617 25 ss.. ppiieettrroo 2,67 0.36 (13.6%) 28 4 1200 661 40 ccaannnneettiieelllloo 4,35 0.33 (7.7%) 21 5,7 1270 579 40 ss.. mmaarrccoo 30,3 2.6 (8.5%) 16 8,2 1425 701 70 ffoorrmmuullee aaddoottttaattee ggiiaannddoottttii ppeezzzzoollii ppuugglliissii vveennttuurraa 44 √ ss ++ 11,,55 ll 66ll 22//33 ((hhmmaaxx--hhoo)) 00,,112277 √ ss// √ii bbaacciinnoo –––––––––––––––––––––– 00,,005555 ll// √ii 00,,88 √ hhmm - hhoo ssccuurroolliilllloo 24,7’ 13,22’ 1h 06’ 15’ ffooiiaannoo 19,5’ 7’ 48’ 9’ ppiiaazzzzaa ggrraannddee 18,48 4’ 40,54’ 7’ ccooggnnuuoolloo 19,26 12,44’ 58,98’ 9’ ss.. ppiieettrroo 37,7 25’ 1h 25’ 23’ ccaannnneettiieelllloo 54,56 41’ 1h 46’ 37’ ss.. mmaarrccoo 1h 42’ 1h 12’ 2h 10’ 1h 52’ 29pericolosità connessa a processi alluvionali ... lungo il versante settentrionale del monte pendolo, causando 42 vittime. eevveennttoo ddeell 1144 oottttoobbrree 11887788 nell’archivio storico del comune di castellammare, c’è copia della relazione che l’allora sindaco scherillo inviò al prefetto del circondario in occasione dell’alluvione del 14 ottobre 1878. in questo documento è riportata la seguente cronaca dei fatti. “nella notte dal 13 al 14 corrente mese, dopo un lungo e cupo rumoreggiare di tuoni, e dopo vivissimo lampeggiare, una pioggia torrenziale scaricavasi nelle nostre pianure e sulle montagne del limitrofo comune di gragnano, e raccoltasi negli alvei dei rivi cannitello e san marco rompendo gli argini e straripando impetuosa invadeva le strade di questa città più vicine alla stazione e quelle dette surripa e san vincenzo travolgendo ogni ostacolo. case coloniche quasi sommerse, grida strazianti di intere famiglie che invocavano soccorso, colpi di fucile per richiamare gente ed avvertire nuovi pericoli, le vie, le botteghe quasi tutte abitate ripiene di acque e tab.3 eventi alluvionali e relativi danni. per l’ubicazione vedi fig. 6. alluvial events and related damages. for the location see fig. 6. aannnnoo nn.. uubbiiccaazziioonnee ddeessccrriizziioonnee ddaannnnii 11771155 1 altezza del santuario di pozzano piena del rivo foiano distruzione del ponte sul rivo 2 banchina circolo velico interrimento tunnel sbocco rivo s. pietro 3 via de turris ingenti danni 11776644 4 via coppola alluvionamento detritico-fangoso all’abitato 5 via del gesù 6 via mele 2 vittime e molti 11887788 7 vico minichiocchio alluvionamento fangoso h 1,5 m feriti, notevoli danni 8 stazione f.s. allagamento alle abitazioni e alla 9 via rispoli rete ferroviaria 10 via roma alluvionamento fangoso di 1-2 m cm 5 vittime, numerosi 11993355 11 corso v. emanuele interrimento dei seminterrati feriti, 3000 senzatetto 12 corso g. garibaldi e danni alle case, alla 13 stazione f.s. allagamento rete stradale e alla 14 piazza grande alluvionamento fangoso h 1 m stazione ferroviaria 11994499 15 via tavernola alluvionamento fangoso h 1,5 m danni ai seminterrati 16 salita quisisana frana scorrimento crollo 17 via bonito alluvionamento fangoso 18 s. caterina alluvionamento fangoso h 1,80 2 banchina circolo velico interrimento sbocco tunnel rivo s. pietro 19 via bonito alluvionamento fangoso fino ai primi piani delle case 20 tra via s. caterina e via bonito interrimento sottopossaggio 21 via bonito alluvionamento fangoso 5 feriti e 50 persone 22 piazza fontana grande alluvionamento fangoso h 1,5 m sgomberate, ingenti 11998877 23 via duilio alluvionamento fangoso h 0,8 m danni al centro 24 via acton alluvionamento fangoso h 1 m storico con 25 via acton (rivo foiano) interrimento tunnel interruzione della 26 via acton ex pensione teta alluvionamento detritico-fangoso h 1 m s.s. 145 e di via 27 piazza grande alluvionamento detritico action 28 letto rivo cognuolo altezza via fratte alluvionamento detritico-fangoso 29 via fratte interrimento tunnel 30 rivo piazza grande altezza via fratte frana per scalzamento al piede 31 dx orografica rico foiano nei pressi di via salita di pozzano frana scorrimento-crollo 32 via delle terme 22000000 33 via s. caterina alluvionamento fangoso danni ai seminterrati di melma fino ad oltre un metro di altezza. i danni sono gravissimi ed intere famiglie perdettero tutto quel poco che costituiva la loro fortuna, rimanendo prive anche dei letti trasportati dalle acque.” nel resoconto sull’accaduto dell’allora commissario vincenzo oliva, si legge: “nella notte di domani a lunedì 14 ottobre verso il tocco p.m. una piena smisurata si verificava sul canale che divide il fondo di de rosa dalla fabbrica d’alcool fusco sulla strada che mena al camposanto. in un baleno le acque sormontarono il muro di cinta ed abbattevano gli argini, irrompendo furiosamente come mare in tempesta, ed in men che non si pensa allagava tutta la circostante campagna, precipitando dalla parte di castellammare che dalla suddetta fabbrica fusco giunge fino al quartuccio. un panico generale spargeasi tosto per la città, alcune case rurali venivano abbattute alcune altre circondate da per ogni dove dalle acque rimanevano bloccate in balia degli eventi. le tre strade di castellammare, via napoli, marina, vittorio emanuele, presentavano tre mari vorticosi che facevano orrore alla semplice vista, orrore e spavento maggiore perché nel mezzo della notte.” sempre nel già menzionato archivio c’è la relazione, degli ing. g. vitelli e g. vanacore, sui danni provocati dall’alluvione. i due tecnici fanno una dettagliata descrizione e scrivono che dalla strada nocera (all’altezza del ponte san marco) fino a via napoli “furono danneggiati dall’alluvione ettari quattro ed are 88 circa di terreno, con restare su quella superficie uno strato di lapillo ed arida sabbia dell’altezza di metri 0.60.” altri fondi, bassi, magazzini e abitazioni furono coinvolti dalla furia delle acque in via napoli, via marina e nelle strade vicine, “la lava ha depositato uno strato di sabbia frammista a pietre calcaree e lapillo dell’altezza media di metri 0.80, abbattendo e distruggendo una gran quantità di alberi e viti.” in questa relazione è fatto riferimento anche il rivo san pietro che, rispetto al rivo cannitello e al rivo san marco, ha causato danni minori, “l‘altro torrente denominato san pietro per dove hanno scolo le pluviali acque che sogliono derivare dalle montagne del sovrastante comune di pimonte, nell’alluvione in parola raccolse pure le abbondanti acque che derivarono dalla strada provinciale gragnano castellammare. il volume dell’acqua non capendo nell’alveo di quel torrente straripò inondando la strada surripa, poi quella di santa maria dell’orto, largo quartuccio e largo principe umberto, lasciando su quei pavimenti molto fango e materiale.” nell’emeroteca della biblioteca universitaria abbiamo trovato alcuni giornali contemporanei degli eventi descritti. dalle cronache riportate sul quotidiano “roma” del 15 ottobre 1878 si apprende che: “verso la mezzanotte di domenica (13 ottobre) sulle montagne di gragnano e limitrofi territori avvenne una pioggia dirotta. la pioggia non potette contenersi nell’alveo dei rivoli san marco e san pietro, e straripava inondando il lato nord-est della città di castellammare, travolgendo seco quanto invadeva, ed atterrando tutti gli ostacoli che incontrava. le masserie coloniche della contrada tavernola furono gravemente danneggiate, e la corrente prese la strada di nocera, dividendosi in due, l’una invase la piazza principe di napoli e la strada napoli, l’altra, atterrando le mura del fondo trojano, per la strada camposanto atterrava i muri del giardino fusco e fondo cannodanicello, ed allagava varie case coloniche ove erano parecchie famiglie. le acque eran dal suolo elevate oltre un metro. di vittime se ne accennano a due, sarebbero due fanciulli.” dallo stesso quotidiano, il 17 ottobre 1878, si legge: “a memoria d’uomini non si ricorda un disastro così spaventevole. i danni sono gravissimi: intere famiglie perdettero tutto quel poco che costituiva la loro fortuna. finora si ha notizia di una sola vittima un fanciullo di nove anni – ma si teme sempre che giungano particolari dolorosi.” eevveennttoo ddeell 2200 aaggoossttoo 11993355 verso l’imbrunire del 20 agosto 1935, per violenti rovesci temporaleschi, accompagnati, localmente, dallo straripamento del rivo san marco, la zona orientale della città di castellammare di stabia fu colpita da una terribile alluvione, seguita dal tragico bilancio di cinque vittime trai quali tre bambini; più di trecento furono poi i senzatetto. anche il vicino comune di gragnano, dovette far fronte al triste epilogo dell’evento alluvionale, compiangendo altre cinque vittime e fronteggiando la richiesta d’aiuto delle numerose famiglie alluvionate. le cronache dei quotidiani dell’epoca (il mattino, 1935) descrivono un violento nubifragio che interesso l’area dei monti lattari con flussi fangosi che invasero le strade della città di amalfi e la parte più orientale dell’abitato di gragnano (piazza della conceria), ma soprattutto l’alluvione colpì la contrada tavernola a castellammare di stabia “......da gragnano,..., è affluita su castellammare una valanga di acqua che ha trascinato lapilli masserizie, pietre, tronchi d’alberi. ...” .( il mattino, 22.08.1935 ) in una lettera inviata all’alto commissario per la provincia datata 24/9/1935, l’allora podestà del comune di castellammare di stabia, catello de simone, descriveva scrupolosamente gli effetti del disastro fornendo preziosissime indicazioni che ci hanno permesso di definire i dettagli dell’alluvione. da questa si evince che: la zona più fortemente colpita si presentava a forma triangolare estendendosi tra la foce del torrente san marco, il ponte dello stesso sulla strada provinciale per nocera e la foce del rivo cannetiello. all’interno di questa zona, gli scantinati furono completamente invasi dall’acqua che portava in sospensione materiale argilloso e lapillo, mentre una corrente di materiale limaccioso, imperversava per le strade con un’altezza variabile da 2 a 0.5 m. lasciando un residuo solido dello spessore medio di un metro. tutti i piani terra furono dunque preda della fanghiglia e a stento alcune famiglie fecero in tempo a cercare scampo ai piani superiori. fuori di tale zona si verificarono allagamenti con strade e terreni ricolmati, per uno strato vario di alcune decine di cm., di terra rimaneggiata di natura limosa e di piccoli ciottoli. un’ulteriore testimonianza è raccolta da palumbo (1940) che nella sua antologia storica di stabia e castellammare di stabia recita : “la muraglia fangosa procedeva travolgente, distruttrice, dilagando con impeto contro i muri dei fabbricati e facendo larghi e vorticosi gorghi al centro delle piazze, mentre erano trascinati tronchi d’albero, carretti, sterpi, mobili strappati a terranei e baracche d’abitazione, lastroni di asfalto smossi dal piano stradale delle vie percorse e rottami di ogni genere”. 30 a. santo et al. eevveennttoo ddeell 99 nnoovveemmbbrree 11998877 il pomeriggio del 9 novembre 1987, un forte nubifragio si scatenò sulla campania, colpendo molti centri della provincia di napoli e lasciando ferite profondissime nel territorio comunale di castellammare di stabia. l’indomani del triste evento, il quotidiano napoletano il mattino, apriva la sua pagina di cronaca con un articolo intitolato “il giorno del diluvio”. in esso, il giornalista antonio pane descriveva i luoghi del disastro, annotando 50 persone sgomberate e 5 ricoverate in ospedale per sindrome da assideramento. da una ricostruzione fatta attraverso documenti giornalistici, comunali e testimonianze dirette, la zona più danneggiata è risultata il vecchio sobborgo marinaro di castellammare, tra le vie santa caterina e bonito; qui, tutte le abitazioni furono invase dall'acqua che raggiunse circa i 2 metri d'altezza, come testimoniato dalla traccia del flusso fangoso sui muri. in quest'area, il materiale fangoso misto a detrito e quant'altro trasportava la corrente ha prima occluso il tratto sotterraneo del rivo cognuolo, per poi intasare il passaggio pedonale sotto i palazzi tra via s. caterina e via bonito che costituiva la via preferenziale del deflusso superficiale. tutto ciò ha generato quello che possiamo definire un "effetto diga", che ha spinto l'acqua verso vie di fuga laterali ed attraverso l'abitazione al primo piano sopra al citato sottopassaggio. in questo scenario numerose persone rischiarono la vita, ed in particolare alcuni anziani rimasero bloccati nelle loro abitazioni e furono soccorsi semi assiderati. l’intera popolazione dovette fronteggiare ingenti disagi con la città paralizzata per la gran quantità di detriti riversatisi nelle strade, inoltre piccole frane danneggiarono e ostruirono le sedi stradali della statale sorrentina e della via action, interrompendo le uniche vie di comunicazione da e per i centri costieri sorrentini. le forze di soccorso, per lo più militari, giunte nelle ore successive trovarono uno scenario catastrofico, infatti, il flusso fangoso, oltre a colmare i bassi, si era riversato per le strade lasciando fango, tronchi d’albero e massi di grandi dimensioni. le tracce del passaggio del flusso furono visibili per diversi giorni dall’evento con i muri imbrattati di fango per un’altezza, rispetto al livello stradale, variabile dai 50 cm fino ai 2 m nella zona più fortemente colpita. eevveennttoo ddeellll’’ 88 oottttoobbrree 22000000 l'ultimo evento della ricerca storica riguarda l'episodio che nel pomeriggio dell'8 ottobre 2000 fece rivivere nell'abitato di castellammare di stabia le scene dell'alluvione dell'87. dai quotidiani e da testimonianze locali si apprende che, a causa di mezz'ora di pioggia, il rivo fratte ha riversato in via santa caterina circa duemila metri cubi di fango, che hanno invaso i locali al piano terreno dei palazzi, inducendo gli abitanti ad abbandonare le proprie abitazioni per rientrarvi solo a tarda sera. a tal proposito il mattino del giorno 9 titolava "mezz'ora di pioggia e torna l'incubo frane; fiume di fango nel centro storico di castellammare". la ricerca storica ha dunque evidenziato che nell’area di castellammare si sono ripetuti con una certa frequenza fenomeni di alluvionamento con ricorrenza di almeno di 50 anni. tutti i fenomeni vengono descritti come piene improvvise, con riposte alle precipitazioni, in termini di tempo, molto brevi. il materiale che ha invaso la città viene descritto in generale come una massa fangosa, molto fluida che ha invaso le case per 1-2m di altezza, arrivando in alcuni casi sino al primo piano delle abitazioni. in alcuni casi le masse fangose hanno trascinato grandi blocchi di calcare e tronchi di alberi che hanno sfondato alcune case. i risultati, in termini di danni, sono rappresentati da diverse vittime, case distrutte e numerose abitazioni e strade invase dal fango. 66.. ccaarrttaa ddeeii ddaannnnii rriiccaavvaattaa ddaallllaa rriicceerr-ccaa ssttoorriiccaa ee rreellaazziioonnii ttrraa ii ffeennoommeennii ddii aalllluuvviioonnaammeennttoo ee llee mmooddiiffiiccaazziioonnii aannttrrooppiicchhee ddeell rreettiiccoolloo iiddrrooggrraaffiiccoo questa carta (fig. 6) riassume i dati della ricerca storica a partire dal 1715; le aree colpite sono state distinte con colori diversi in funzione dei diversi eventi alluvionali. chiaramente, le notizie relative ai danni sono più dettagliate e precise per gli ultimi eventi, specie per quello del 1987. dalla lettura della carta dei danni si evince che, negli ultimi trecento anni, l'abitato di castellammare di stabia è stato ripetutamente interessato da eventi di tipo alluvionale e che alcune zone, in prossimità dei torrenti maggiori, risultano colpite più volte. l’analisi di carte topografiche dell’area edite tra il 1872 ed il 1990 ha evidenziato che le modificazioni indotte sui bacini idrografici dalla continua urbanizzazione, hanno condizionato le caratteristiche idrologiche dei corsi d’acqua in diversi modi. innanzitutto, una percentuale sempre maggiore di superficie è stata resa impermeabile all’infiltrazione delle acque a causa della crescente cementificazione, provocando l’aumento del ruscellamento superficiale e riducendo il tempo di concentrazione. in altri casi è stata ristretta la naturale luce degli alvei (ponti, sottopassi) e spesso, non si è tenuto conto delle distanze di rispetto, relative alle aree di possibile esondazione. non è scopo di questo lavoro entrare nel merito dell’espansione urbanistica o delle modificazioni di tipo idraulico, ma la ricerca dei depositi e delle forme recenti da attribuire a fenomeni di alluvionamento non poteva prescindere, in un’area così fortemente urbanizzata, dalla ricostruzione e dalla modificazione antropica dei naturali corsi d'acqua. a tale scopo si è rivelato utile reperire riferimenti cartografici coevi agli eventi alluvionali studiati attraverso il confronto di una serie di carte topografiche in sequenza cronologica, in particolare (fig.7) : • rappresentazione topografica risalente al 11881122 • tavola della città ad opera di f. fantacchiotti del 11887755 • tavoletta topografica dell’i.g.m. 1/25.000 del 11990099 • tavoletta topografica dell’i.g.m. 1/25.000 del 11995544 • carta topografica del comune 1/10.000 del 11999900 dall’osservazione dell’antica rappresentazione della città, risalente al 1812 (fig.7), si nota che l’abitato di castellammare di stabia era limitato al tratto costiero compreso tra il cantiere navale e tutta la conoide del rivo san pietro. in questa carta i tratti terminali dei rivi san pietro, cognuolo e piazza grande risultano scorrere al di sotto dell’antico centro urbano, mentre si presen31pericolosità connessa a processi alluvionali ... ta inalterato il percorso degli altri rivi. questa carta è stata usata anche come riferimento per l’interpretazione dei danni causati dall’alluvione del 20\1\1764. dalla carta dei danni risulta che l’area colpita da questa alluvione è circoscritta solo alla conoide del rivo san pietro. questo, però, non esclude che anche gli altri rivi siano stati interessati da intensi fenomeni di trasporto torrentizio, dato che all’epoca l’abitato di castellammare, come già evidenziato, aveva dimensioni molto più limitate rispetto a quelle attuali. nel periodo fine ottocento inizio novecento la città, così come appare nella riproduzione dell’architetto f. fantacchiotti e nella tavoletta i.g.m., (fig.7) risulta estesa verso nord occupando gran parte della conoide del rivo cannitello, e una ristretta fascia costiera fino allo sbocco del rivo s.marco. dalle due carte si osserva che l’ultimo tratto del rivo cannetiello a partire dalla via roma è tombata. la carta del fantacchiotti offre una rappresentazione della città al 1875, pochi anni prima dell’evento alluvionale del 1878, ed è stata per questo utilizzata come supporto per la localizzazione dei danni, essendo cambiata, nel corso degli anni, la toponomastica delle strade. dall’osservazione della distribuzione dei danni si può osservare che le zone colpite dai rivi san marco, cannitello e san pietro corrispondono a quasi tutto il territorio allora urbanizzato; non si può ovviamente escludere che l’area alluvionata fosse molto più ampia. un “flash fotografico” della situazione nel dopoguerra, possibile grazie alla carta del 1954, mostra un ulteriore sviluppo urbanistico, che interessa completamente la conoide del rivo cannitello e parte di quella in sinistra orografica del rivo s. marco. anche in questo caso si è riscontrata una certa corrispondenza tra l’espansione urbanistica e le modificazioni subite dai corsi d’acqua. infatti, il tratto tombato del rivo cannitello è stato esteso fino all’apice della conoide mentre il rivo san marco è stato canalizzato nel tratto che va dalla strada ferrata alla spiaggia (vedi carta 1954). dalle notizie rinvenute dalla ricerca storica, è possibile affermare che la conoide del rivo san marco era già parzialmente urbanizzata quando si verificò la terribile alluvione del 20 agosto 1935. infatti, dalla carta dei danni risulta che la zona più fortemente colpita era quella in sinistra orografica del rivo san marco, mentre nella parte destra non sono stati riportati danni essendo questa poco urbanizzata e destinata ad uso agricolo (vedi carta 1954). 32 fig. 6 carta dei danni relativa agli eventi alluvionali succedutesi dal 1715 ad oggi nell'area di castellammare di stabia. i numeri si riferiscono alle località citate nella tab. 3. map showing the damages produced by the alluvial events occurred since 1715 in the area of castellammare di stabia. the numbers refer to the localities of tab.3. a. santo et al. 33 fig. 7 carte storiche (1812-1990) rappresentanti l'evoluzione urbanistica e le modificazioni antropiche della rete idrografica. a) alvei naturali; b) tratti di alvei tombati o cementati. nella carta topografica del 1990 i colori indicano lo sviluppo del centro urbano nel tempo. historical maps (1812 –1990) showing the urban evolution and the anthropic modifications of the hydrographic network. a) natural river-bed; b) modified river-bed. in the 1990 topographic map the colours represent the development of urban area during time. pericolosità connessa a processi alluvionali ... per la situazione urbanistica attuale e per l’alluvione del 1987, si fa riferimento alla carta del 1990, questa è stata usata anche come base cartografica per sintetizzare l’evoluzione urbanistica e le modificazioni subite dai rivi nel tempo. nella rappresentazione dell’abitato di castellammare di figura 7, si evince che negli ultimi decenni si è avuta una notevole espansione urbanistica verso la piana del sarno e lungo la fascia pedemontana. i rivi che hanno risentito maggiormente di questo ulteriore sviluppo sono il san marco, che è stato totalmente tombato al di sotto dell’abitato ed il cannitello il cui tratto tombato é stato esteso dalla paleofalesia alla statale ss. 145. esempi dell'intensa modificazione antropica subita dalla rete idrografica negli ultimi anni sono: la costruzione del fabbricato ex pensione teta, che occupa il letto del rivo scurolillo in prossimità della foce; le gallerie anas realizzate lungo la ss 145, perpendicolarmente al rivo foiano (fig. 8). queste costituiscono un sito di particolare rischio; infatti, nel gennaio del 1997, una di esse è stata già invasa da una colata rapida di fango (frana di pozzano, di crescenzo & santo, 1999). in conclusione tutti i rivi hanno dato nel passato problemi di trasporto solido per alluvionamento, in occasione dei quali hanno avuto un ruolo fondamentale le numerose restrizioni delle sezioni fluviali, riconducibili alle modificazioni antropiche dei naturali corsi e all'occlusione delle tombature con cui i rivi raggiungono il mare. 77.. rreellaazziioonnii ttrraa pplluuvviioommeettrriiaa eedd eevveennttii aalllluuvviioonnaallii la piovosità nell’ambito della penisola sorrentina, (rossi & villani, 1994; de falco et al, 1997) presenta una distribuzione disomogenea, in quanto risulta condizionata dalla particolare configurazione morfologica dei monti lattari; questi rilievi costituiscono una barriera orografica che influenza in modo diverso le precipitazioni sui due versanti, inducendo una maggiore concentrazione degli eventi meteorici nel periodo invernale sul versante sorrentino e nel periodo autunnale su quello amalfitano. questa variabilità è ulteriormente confermata dall’analisi dei dati pluviometrici della serie storica 1921-1990, che ha permesso a rossi & villani (1994) di suddividere in due sottozone pluviometriche l’area penisola sorrentina-monti lattari. inoltre, in base all’analisi dei dati pluviometrici medi annui relativi allo stesso periodo, de falco et al., (1997) hanno redatto la carta delle isoiete che mostra valori più elevati nel settore tra nocera, gragnano e positano, posto a quota maggiore, all’interno del quale ricade anche il territorio di castellammare di stabia (fig. 9) . per quanto riguarda i dissesti che frequentemente colpiscono la penisola sorrentina, questi hanno un rapporto di causaeffetto con gli eventi meteorici che è ampiamente documentato in letteratura dall’analisi delle isoiete di alcuni eventi pluviometrici del passato e della serie storica delle frane. per l'analisi delle relazioni tra pluviometria ed eventi alluvionali che hanno interessato i bacini idrografici di nostro interesse, sono stati analizzati i dati relativi ai pluviometri di castellammare (18 m s.l.m.) e gragnano (173 m s.l.m.) reperiti dagli annali idrologici dell’istituto idrografico e mareografico di napoli. in particolare sono stati considerati i valori di pioggia giornaliera superiore agli 80 mm nel periodo 1935-1988 (fig.10). il confronto con gli episodi alluvionali noti, purtroppo, è stato possibile solo per gli eventi del 20 agosto 1935 e del 9 novembre 1987; per essi sono stati considerati i valori di pioggia giornalieri e la pioggia cumulata per un periodo, antecedente di circa tre mesi. nel caso dell’alluvione del 1935, che fa riferimento al rivo s. marco il cui bacino idrografico ricade nell’area di competenza del pluviometro di gragnano, si sono verificati, dal 1° giugno al 20 agosto, solo otto giorni piovosi con un valore di pioggia cumulata di 116 mm, cui si sono aggiunti i 94 mm del giorno 20 (fig. 10). per quanto concerne l’evento del 1987, l’eccezionale pioggia di 182 mm del 9 novembre è stata preceduta da soli 137,6 mm di pioggia cumulata nei tre mesi antecedenti. entrambi gli eventi, dunque, si sono verificati dopo un periodo di scarse precipitazioni, in coincidenza di un picco piovoso isolato di tipo temporalesco. dal grafico in fig.10, si evince inoltre che valori di precipitazioni giornaliere simili a quelli registrati per gli eventi alluvionali del 1935 e del 1987 si sono ripetuti più volte senza effetti degni di rilievo. tali considerazioni, anche se prive di valore quantitativo, inducono a pensare che gli eventi alluvionali potrebbero essere stati causati da una particolare concentrazione oraria delle piogge. ciò si intuisce dal contenuto di alcuni documenti rinvenuti nella ricerca storica come la descrizione coeva dei fatti del notaio vincenzo d’ayello jr.; “ temporale o sia tempesta grande sortita nel 20 gennaio 1764 …principiata verso l’ore sette ed aumentata sino alle ore 11”., dalla relazione tecnico-sanitaria del municipio del 5/09/1935: all’imbrunire del 20 agosto e per non più di un ora si scatenò un violentissimo nubifragio. 34 fig. 8 ingresso della galleria anas in costruzione che attraversa il vallone di foiano. sulla sinistra sono ben evidenti i depositi di conoide alternati a livelli piroclastici tardo pleistocenici. the building tunnel that crosses the foiano creeck. on the left are exposed alluvial fan deposits with intercalation of upper pleistocene pyroclastic levels. a. santo et al. 35 fig. 10 a) istogramma delle massime precipitazioni giornaliere (> 80 mm) registrate dai pluviometri di castellammare mare di stabia e gragnano nell'intervallo 1935-88. b) piogge giornaliere registrate dalla stazione pluviometrica di gragnano nei tre mesi antecedenti l'evento del 20/08/1935 c) piogge giornaliere registrate dal pluviometro di c\mare di stabia nel periodo antecedente l'evento alluvionale del 09/11/1987. a) histogram of maximum daily rainfall (> 80 mm) recorded from rain-gauges of castellammare and gragnano between 1935 and 1988. b) daily rainfall recorded from rain-gauge of gragnano during the three months before the event of the 20/08/1935. c) daily rainfall recorded from rain-gauge of castellammare di stabia before the alluvial event of 9/11/1987. fig. 9 carta delle isoite della penisola sorrentina-monti lattari. (da de falco et al, 1997, modif.) isoiete map of the surrentine peninsula – lattari mts. (from de falco et al., 1997, modified). 88.. ccoonncclluussiioonnii lo studio geologico-geomorfologico ha evidenziato che una estesa porzione dell’abitato di castellammare è localizzata su conoidi oloceniche accresciutesi anche in età storica. la ricerca storica condotta ha permesso di documentare numerosi eventi alluvionali di cui si era persa la memoria dalla fine del settecento ad oggi, di localizzare e distinguere i danni relativi ai singoli eventi e di redigere una carta dei danni in cui sono evidenziate le aree colpite da uno o più eventi alluvionali, nel periodo che va dal 1764 al 1987. tale carta è stata ricostruita valutando anche l’evoluzione urbanistica dell’area, utilizzando riferimenti cartograpericolosità connessa a processi alluvionali ... fici coevi agli eventi alluvionali studiati; in particolare sono state utilizzate carte risalenti rispettivamente al 1812, 1875, 1909, 1954 e 1990, allo scopo di correlare i danni all’evoluzione urbanistica. da questo confronto è emerso che sicuramente eventi della stessa intensità, potrebbero interessare aree maggiori, vista la notevole espansione urbanistica e l’alta densità demografica di questo territorio. dalle stesse carte è stato possibile seguire nel tempo le modificazioni antropiche subite dai “rivi” (alvei tombati, cementificazione, restringimento ecc.). inoltre, dalle notizie storiche sulle alluvioni, si è potuto accertare che i punti di esondazione sono stati talvolta localizzati in corrispondenza dei restringimenti d’alveo (“effetto diga” causato da tronchi e massi trasportati dalla corrente ). l’analisi storica e l’analisi dei dati pluviometrici disponibili suggeriscono che gli eventi si sono verificati in coincidenza di picchi piovosi isolati. la particolarità di queste precipitazioni va ricercata nella loro concentrazione oraria, che purtroppo non può essere quantificata a causa della mancanza di dati pluviometrici, ma che trova conferma nelle minuziose descrizioni degli eventi rinvenute nella ricerca storica. lo studio dei bacini idrografici ha consentito di definire i principali parametri fisici che li caratterizzano e di calcolare il loro tempo di corrivazione che si è dimostrato essere sempre prossimo o inferiore all’ora. sulla base dei dati raccolti nel territorio di castellammare di stabia si devono quindi evidenziare le condizioni di alta velocità e pericolosità dei fenomeni alluvionali che in un’area così altamente urbanizzate si traducono in un elevato rischio. molti altri centri abitati campani presentano le stesse caratteristiche avendo condizioni geologico-geomorfologiche predisponenti a tali fenomeni quali: condizioni morfometriche dei bacini e cioè gradienti medi di pendenza abbastanza elevati (30 40 %) ed elevata energia di rilievo (1000 metri di dislivello su bacini di dimensioni estremamente ridotte), associati a bassi tempi di corrivazione; estesa presenza di coperture piroclastiche sui versanti dei bacini idrografici che favoriscono il ruscellamento superficiale e contribuiscono ad aumentare il trasporto solido degli alvei. in questi contesti, gli studi multidisciplinari rivolti alla mitigazione del rischio per fenomeni di alluvionamento, devono tener conto di un approccio geologicogeomorfologico di dettaglio, atto alla individuazione dei conoidi attivi, accompagnato da una accurata ricerca storica soprattutto perché quest’ultima ha mostrato più volte (migale & milone 1998) così come per le frane, che i fenomeni alluvionali possono ripetersi con tempi di ritorno non necessariamente brevi (dell’ordine dei 50100 anni) che spesso hanno fatto dimenticare all’uomo le condizioni di alto rischio di alcuni territori. rriinnggrraazziiaammeennttii gli autori desiderano ringraziare il prof. sorriso valvo per gli utili consigli nella revisione critica del manoscritto. lavoro stampato con fondi ex murst 60% e 40%. resp. prof. de riso r. llaavvoorrii cciittaattii aucelli a., cinque a. & merola d., (1996) discriminazione cronologica di eventi deformativi fragili lungo il margine settentrionale dei monti lattari sulla base di dati geologici e geomorfologici. il quaternario, 99 (1), 319-324. archivio storico di castellammare relazioni tecnicoamministrative. municipio di castellammare di stabia, napoli. barra d., bonaduce g., brancaccio l., cinque a., ortolani f., pagliuca s. & russo f. 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(1997) ricostruzione di eventi deformativi di versante tardo-quaternari ed olocenici attraverso studi geomorfologici e datazioni radiometriche th/u: l’esempio dell’area di vico equense (campania). “il quaternario” 1100 (2), 1997, 447-484. sigurdsson h., cashdollar s. & sparks s. r. j. (1982) the eruption of vesuvius in a.d. 79: recostruction from historical and volcanological evidence. am. journ. archeology, 86. travaglini g., valdinucci a. (1964) sulla frana di nerano e termini nel febbraio 1963. università di napoli istituto di idraulica agraria. tropeano d., casagrande f., luino f., cescon c. (1996) processi di mud-debris flow in val cenischia (alpi graie): osservazioni nel bacino del t. marderello. geam, quaderni di studi e documentazione, anno xxxiii n. 2233. 5-31. vallario a. (1992) le frane nelle piroclastiti della campania, in a. vallario frane e territorio. le frane nella morfogenesi dei versanti e nell’uso del territorio, liguori ed. napoli. vallario a. (2001) il dissesto idrogeologico in campania. cuen ed. napoli. 37pericolosità connessa a processi alluvionali ... ms. ricevuto il 13 giugno 2001 testo definitivo ricevuto il 15 febbraio 2002 ms. received: june 13, 2001 final text received: february 15, 2002 ojs 631 monegato et al proofcopy 6.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 35 (2), 2022, 1-16 1. introduction glacial dispersal trains (shilts, 1982) i.e. trails of deposits and clasts eroded from a bedrock source, transported downglacier and deposited in the stratigraphic record (cummings & russell, 2018) represent an important tool for understanding the flow of glaciers and the delivery of glacigenic sediments, including the distribution of particular types of rocks or minerals in the glacial till (e.g., shilts, 1993; mcclenaghan et al., 2001). empirical tests in tills of boreal ice sheets (e.g., larson & mooers, 2004) highlight the key role that distance from the source areas plays in the downflow distribution of the indicator lithotypes in glacigenic deposits. in glaciated mountains the dispersal train largely follows the major valleys towards the piedmont plains. gravitational processes (e.g., rock fall, slope failures) occurring at the interface of the glacier and the ice-free valley slopes promote debris accumulation and its consequent embedding into the ice (e.g., evans, 2003; goodsells et al., 2005). supraglacial delivery including large (erratic) boulders represents a peculiar characteristic of mountain glaciers. erratic boulders evidence past glacier extents, even where no till can be found. they are key to inferring the pathways and transfluences within the network of valley glaciers that developed in the alps during pleistocene glaciations (e.g. van husen, 2004; kelly et al., 2004; bini et al., 2009). understanding the dynamics of large mountain glaciers during pleistocene glaciations is intriguing because present-day analogs are scarce and located at different latitudes (i.e. alaskan range or patagonian andes) or at different elevations (himalaya). modern glaciers with piedmont lobes are very rare and limited to the alaskan range, kunlun mountains and iceland. consequently, a multidisciplinary approach is needed to reconstruct the functioning of past alpine ice-stream networks. for the european alps, the excellent knowledge on last glacial maximum (lgm) glacier extent has fostered numerous glacier modelling studies and related ela interpretations (becker et al., 2016; jouvet et al., 2017; cohen et al., 2018; seguinot et al., 2018; imhof et al., 2019; višnjevi� et al., 2020; seguinot & delaney, 2021; del gobbo et al., 2022). modelling results additionally provide information on paleoglacier velocity, sliding, thickness and flow path. even if the simulations show certain discrepancies with the sedimentological and geomorphological data with regard to glacier extent and ice thickness, they raise important questions about ice development during major glaciations and the building of interconnections among the valley glaciers (bini et al., 2009; seguinot et al., 2018). https://doi.org/10.26382/amq.2022.07 the ticino-toce ice conveyor belts during the last glacial maximum. giovanni monegato 1, sarah kamleitner 2, franco gianotti 3, silvana martin 4, cristian scapozza 5, susan ivy-ochs 2 1 institute of geosciences and earth resources, national research council, padova, italy. 2 laboratory of ion beam physics, eth zurich, zurich, switzerland. 3 dipartimento di scienze della terra, università di torino, torino, italy. 4 dipartimento di geoscienze, università di padova, padova, italy. 5 istituto scienze della terra, scuola universitaria professionale della svizzera italiana supsi, mendrisio, switzerland. corresponding author: g. monegato <giovanni.monegato@igg.cnr.it> abstract: the provenance and distribution of erratic boulders of the ticino-toce glacier network yields key information for determining glaciers’ paleoflow and highlights the interaction between two major alpine glacier systems during the last glacial maximum (lgm). boulders in the central and western parts of the verbano, as well as in the smaller orta end moraine systems, originate from the toce catchment. erratics pertaining to the ticino mountain basin characterize the eastern flank of the verbano amphitheatre and the glacial deposits in the ceresio system. the wide distribution of toce lithologies in the verbano end moraine system can, despite its smaller overall size, be ascribed to the hypsometry and valley course of the toce catchment. areas with highest-elevation (>4000 m a.s.l.) and a short flow path (<100 km), favored the early spread of the toce glacier. in the first phase of the lgm, the preceding advance of the toce glacier may have suppressed the larger, possibly inert, ticino glacier towards the east forcing its diffluence into the prealpine area of ceresio, which had no local glaciers and was likely impacted by a western branch of the adda glacier. the dynamics of the ticino-toce glacier network during the lgm highlight the role of the topography and location of the accumulation areas in driving differential development of glaciers originating from high catchments that can force nearby glaciers with greater inertia towards a different path. keywords: european alps, last glacial maximum, palaeoglacier, erratic boulder, provenance. . 2 monegato g. et al. reconstructions based on geomorphological/geological data become more difficult moving from the outer sectors of the chain, where piedmont lobes spread onto the plain, to the axial sector, where the accumulation areas were located. in this inner portion of the cathement the landforms related to the glacial maxima are scarce, while glacigenic sediments are present but hardly useful for paleoglacier reconstruction. a key tool for understanding the flow of paleoglaciers and their possible interconnections through transfluences is the provenance of glacial debris and particularly that of erratic boulders carrying the lithological signature of the source catchment (e.g., coutterand et al., 2009; coutterand, 2010; jouvet et al., 2017; braakhekke et al., 2020). large erratic boulders are more suited than smaller clasts for such a task as they are large enough to barely suffer from the possible bias of reworking, as their datings to the lgm have shown (see section materials and methods). while not every type of rock can produce big boulders, those boulders transported on the ice surface would not suffer from mixing and would generally remain on the side of the glacier that they fell onto. an exception in this assumption is related to large landslides, which may scatter the debris across the whole width of the flowing glacier (e.g., menzies et al., 2017; frasca et al., 2020). boulder roundness can additionally inform about the transport position (supraglacial or subglacial). the potential of using erratic boulders to model glacier flow was shown by several studies (florineth & schlüchter, 1998; jouvet et al., 2017; cohen et al., 2018), yet the coupling with chronology is critical. through field studies and different absolute dating techniques, the chronology of the alpine lgm has been refined over the last decades, allowing to depict the lgm ice margin in several sectors of the mountain range (monegato et al., 2007, 2017; reber et al., 2014; scapozza et al., 2014; gianotti et al., 2015; bernoulli et al., 2018; ivy-ochs et al., 2018; braakhekke et al., 2020; kamleitner et al., 2022a; kamleitner et al., 2022b). the present study shows the reconstruction of the paleo -ice streams of the ticino-toce glacier system (fig. 1), one of the largest paleoglaciers in the central southern fig. 1 extent of the lgm ticino-toce glacier system (modified after bini et al. 2009, braakhekke et al., 2020 (orta lobe), kamleitner et al., 2022a (verbano lobe)). red dots represent erratic boulders included in different studies (bernoulli et al., 2018; braakhekke et al., 2020; kamleitner et al., 2022a). 3 the ticino-toce ice conveyor belts during the last glacial maximum alps, and possibly interconnections with neighboring catchments of rhone, reuss, rhine and adda. the lgm chronology of the ticino-toce glacier system was recently assessed by the means of exposure dating of erratic boulders and geomorphological considerations (braakhekke et al., 2020; kamleitner et al., 2022a). this allowed to reconstruct the shape of the orta and verbano piedmont lobes in detail (fig. 1). evaluating the boulders' source areas may allow to infer the flow lines of the ticino-toce ice streams and test existing glacier models (seguinot et al., 2018), which suggest asynchrony in the development between the ticino and the toce valley glaciers. 2. study area the ticino-toce catchment is about 6700 km2 in size and located in the western alps, south of the main alpine divide. the drainage basin is characterized by an unequal distribution of elevation (fig. 1, fig. 2). the highest peaks are located at the western boundary along monte rosa-fletschhorn line with elevations up to above 4600 m a.s.l. whereas, the northern and especially the eastern sectors have accumulation areas below 3500 m a.s.l. the southern parts of the catchment are characterized by several valley reaches, some filled by lakes. the longitudinal profiles of the valleys illustrate the asymmetry between the toce and ticino catchments, with the former being characterized by high gradients and the latter by longer reaches (fig. 3). the ticino and toce valleys are overdeepened (preusser et al., 2010), with the base of bedrock reported at 600 m b.s.l. at the magadino plain, progressively decreasing to maximum basin depth of 800 m b.s.l. halfway between luino and laveno (cazzini et al., 2020). the overdeepening of these valleys, similarly to other valleys on the southern flanks of the alps, is assumed to have formed during the messinian salinity crisis (bini et al., 1978, finckh, 1978, hantke, 1983). debris flow, fluvial and fluvio-deltaic sediments of messinian age (miocene), as well as marine sediments of zanclean age (pliocene), were indeed observed in the valleys between mendrisio (southern switzerland) and varese (northern italy) (bernoulli et al., 2018). nevertheless, this interpretation is debated and a glacial origin of the upstream sections of southern alpine valleys is currently proposed (winterberg et al., 2020). the lake bottom at the outlet of the ossola valley does not show a fluvial incision and, during the messinian, the toce river was inferred to have flowed into the orta valley (cazzini et al., 2020), fig. 2 geological map of the ticino-toce catchment. data synthesized from swisstopo (2005). tinental crust, including the mantle peridotite series, which was tilted vertically and brought to the surface during alpine orogenesis (rutter et al., 2007). a thick sequence of high-grade metapelitic schists referred to as the “kinzigite” formation, intruded by gabbro and diorite plutons at the mantle-crust boundary. these "kinzigite" schists contain mainly garnet, biotite, plagioclase, quartz, sillimanite and possible muscovite (rutter et al., 2007). early permian granites (named graniti dei laghi, gla) intruded the lam (i.e. plutons of mottarone and montorfano). these plutons are unaffected by alpine metamorphism (boriani et al., 1990b). the prealps east of lake maggiore are largely characterized by sedimentary covers of the southalpine domain (bertotti et al., 1993). these are permo-mesozoic (pmc) to tertiary (tc) shelf to basin marine formations. lugano volcanites (lv) outcropping on the left side of the valcuvia valley are of permian age (hunziker & zingg, 1980). the insubric line is crosscut by the toce valley and the ticino valley in the w-e reach of lake maggiore (fig. 2). here the narrow (about 2 km wide) canavese zone (zc; southalpine domain) is in tectonic contact with the ivrea-verbano and sesia-lanzo zones to the south and north, respectively. the canavese zone includes many types of rocks, such as gneisses, schists, permian diorite, serpentinites and sedimentary carbonate and siliceous rocks, that are locally strongly deformed, with a low-grade alpine metamorphism (ferrando et al., 2004). west of bellinzona the tail of the bergell pluton (bg) is characterized by tonalite (schmid et al., 1996). the sesia-lanzo zone (sl) is the first unit showing alpine metamorphism (compagnoni et al., 1977). it is composed of rocks derived from the southalpine domain and forming the distal edge of the adria microplate before the alpine collision (austroalpine domain). sl was subdivided by previous authors into: “gneiss minuti”, “micascisti eclogitici” and “ii zona diorito-kinzigitica” where the bedrock crops out underneath the frontal moraines of the orta end moraine system (braakhekke et al., 2020). 2.1. geological setting the bedrock of the ticino-toce mountain basin (fig. 2) can be split into two major domains (dal piaz, 2010): (a) the southalpine domain with a paleozoic basement and the permo-mesozoic sedimentary covers, both lacking alpine metamorphism; (b) the second domain was affected by alpine metamorphic phases that include: the sesia-lanzo zone (sl), the penninic and the helvetic nappes. the second domain is characterized by a stack of basement and cover nappes with high -pressure alpine metamorphism of late cretaceous eocene age and a late eocene-early oligocene greenschist to amphibolite facies overprinting (lepontine dome: frey et al., 1999). the two domains are separated by the periadriatic/insubric lineament, a 1000 km long post-collisional transpressive fault with post-late oligocene to miocene activity. the valleys of lake orta and lake maggiore are situated in the southalpine domain (fig. 2) dominated by palaeozoic metamorphic rocks called massicio dei laghi (mdl), by late variscan volcanic suites and permomesozoic sedimentary covers at the outlets and east of lake maggiore (see geological map of switzerland, 1:500,000; federal office of topography swisstopo 2005; piana et al., 2017). the alpine metamorphism is interpreted to have had only minimal effects on the mdl (rutter et al., 2007), whose main metamorphism is of caledonian (late cambrian-early devonian) to variscan (late devonian-early permian) age (boriani et al., 1990a; pinarelli et al., 1993). the mdl is divided into the ivrea-verbano zone (ivk) and the serie dei laghi (lam) separated by the cossato-mergozzo-brissago (cmb) tectonic line (fig. 2). the ivrea-verbano zone (ivk) is one of the most spectacular sections through lower con 4 fig. 3 longitudinal profiles of the major valleys; those related to the toce catchment are in solid lines, those of the ticino catchment in dashed lines; in dotted line the vedeggio valley related to the transfluence towards the ceresio morainic amphitheatre. blue arrows show the elevation of the major transfluences from the respective glaciers. longitudinal distance from the outern lgm moraines of the verbano according to kamleitner et al. (2022a). monegato g. et al. 5 bordered by a southern marginal shear belt. “gneiss minuti” are albite-white mica gneisses and schists, with a local porphyroclastic texture. locally, "gneiss minuti" complex contains coarse-grained metagranitoids. “micascisti eclogitici” are made of high-pressure (eclogite to blueschist facies) micaschists with jadeitic pyroxene-garnet + glaucophane + chloritoid with intercalated eclogites, glaucophane metabasites and marbles. the term "kinzigite" is used in the alpine literature for indicating high-grade (amphibolite facies) sillimanitefig. 4 photos of glacial landforms and erratic boulders (see table 2) from the ticino-toce systems: a) boulder puffer 11 made of ivk gneiss resting on a rocky relief (right slope of lake orta); b) impressive group of seven right lateral moraines of the verbano glacier lobe on the watershed between the lake maggiore and lake orta basins, supporting many granite boulders (alpe canà); c) sub-rounded boulder vr30 made of gla white granite, which provided a pre-lgm 10be age (alpe canà moraines; kamleitner et al., 2022a); d) small angular boulder vr37 made of lam1 garnet paragneiss (s. michele, eastern slope of lake maggiore, nw of laveno); e) big polished sub-angular boulder vr22 made of aon serpentinite (alpe pala at miazzina on the western slope of lake maggiore); f) velmaio megalith invorio breccia (pmc breccia). other photos of erratic boulders from the orta basin (bugnate 17-18, grassona 25, briallo 33, carcegna 50, colma 20 and armeno 39) are found in braakhekke et al. (2020). photos of boulders vr16, vr31, vr45-46 and vr51-52 from the verbano system are found in kamleitner et al. (2022a). the ticino-toce ice conveyor belts during the last glacial maximum 6 fig. 5 plate of thin section samples (see also table 2): a) vr23, green biotite orthogneiss (lam2); b) vr14, granite (gla); c) vr02, serpentinite (aon); d) vr39, paragneiss (lam1); e) vr37, garnet paragneiss (lam1, fig. 4d), f) vr24, green biotite orthogneiss with myrmekite (lam2); g) vr20, granulite (ivk); h) vr27, garnet orthogneiss (mr1). monegato g. et al. 7 garnet-biotite gneisses of the ivk and of the “ii zona diorito-kinzigitica”. the sl crops out in the lower ossola valley for about 4 km at the anzasca-toce confluence, while it pinches out in the ticino valley near ascona (fig. 2). in the north-western sector, the topmost penninic nappe is the zermatt-saas fee zone (zsfz), which forms a very thin and discontinuous oceanic crust slice in the toce basin (fig. 2). it is predominantly composed of serpentinized ultramafites, associated to mafic rocks (metagabbros, metavolcanites and metasediments) crystallized under high-pressure conditions. towards the east, the zsfz pinches out at the northern tip of lake maggiore. the monte rosa (mr) is an upper penninic continental unit characterized by a large sw-vergent recumbent antiform (berger et al., 2011) with a core composed of high-pressure micaschists and “gneiss minuti” derived from high-grade paleozoic paragneiss (mr1, piana et al., 2017) cropping out along the anzasca valley bottom (fig. 2) and a shell composed of dominant metagranitoid (mr3, frey et al., 1976; piana et al., 2017). these are characterized by k-feldspar megacrystals up to ten centimeters in size, preserved within the alpine schistosity. monte rosa “gneiss minuti” are characterized by albite, fine-grained quartz, white mica, chlorite and garnet. in the micaschists, high-pressure assemblages include chloritoid, phengite, garnet with kyanite, talc, mg-chlorite and glaucophane. the alpine high-pressure assemblages are overprinted by a greenschist tertiary metamorphism (keller et al., 2005) as shown by crystallization of biotite from white mica, albite blastesis (poikiloblasts) and quartz recrystallization to form homogeneous coarse-grained aggregates. the antrona metaophiolite (aon) is a nappe of oceanic crust interposed between the overlying monte rosa and the underlying camughera and moncucco nappes (bigioggero et al., 1981). it crops out on the left side of anzasca valley and more extensively in the upper antrona valley (fig. 2). the aon suite includes serpentinized ultramafites, metagabbros and metabasites (turco & tartarotti, 2006). eclogite metabasite with garnet, amphibole and relict omphacitic clinopyroxene are described by colombi & pfeifer (1986) in the antrona and anzasca valleys. middle penninic unit to the west (toce catchment) is the gran san bernardo (sb). in the central eastern to the eastern sectors of the ticino-toce mountain basin the middle penninic units are characterized by greenschist facies paragneiss and orthogneiss with blueschist relics (bigi et al., 1983). they were grouped (mo-cam-bel) in the geological map of figure 2. the moncucco-orselina (mo) and camughera (cam) are folded together with aon, mr and zs units. they show a medium-grade metamorphic overprinting by the lepontine metamorphism (keller et al., 2005). cam is made of micaschists derived from midto high-grade paleozoic gneisses (paragneiss, orthogneiss, amphibolites) and dominant metagranitoids similar to those of mr3, with alpine high-pressure overprint. mo is composed of a paleozoic basement covered by permocarboniferous sequences including graphitic schists, basic metavolcanites and permian sub-volcanic bodies, suggesting affinity with the gran san bernardo nappe (bigioggero et al., 1981). tambo, bosco and bellinzona nappes are made of paleozoic basement and slices of mesozoic covers and bundner schist (baudin et al., 1993). their lithological setting is similar to that of the monte leone nappe (maxelon & mancktelow, 2005). tambo, bosco, bellinzzona and monte leone nappes are recrystallized under amphibolite facies (biotite, staurolite, garnet). the deep penninic nappes (monte leone, lebendun, simano, lucomagno, leventina, antigorio and verampio, lpn) show a strong lepontine amphibolite facies metamorphic overprint. it is characterized by crystallization of new minerals over the early alpine metamorphism (bigioggero et al., 1981; berger et al., 2011). the lpn are composed of a typical paleozoic basement (paragneisses, orthogneisses, amphibolites), with late paleozoic intrusions and permo-carboniferous to mesozoic sequences similar to the other penninic nappes. these units characterize the innermost sectors of ticino and toce catchments (fig. 2). the ultra-helvetic mesozoic cover sequences and the helvetic gotthard basement (hn), including the permian granitoids (sergeev & steiger, 1995), make up the far northern part of the ticino mountain basin (fig. 2). 2.2. the lgm ticino-toce glacier system the ticino-toce accumulation area is located south of the major rhone and rhine (or vorderrhein) ice domes (fig. 1; kelly et al., 2004; bini et al., 2009). in the inner alpine accumulation areas, additional input of ice could have been added to the ticino basin (4900 km2) by overflowing of the rhone ice dome to the east along bedretto valley via nufenen pass (fig. 2). in leventina valley, the ticino glacier received large ice masses built up in the high-mountain cirques of gotthard pass. downstream of leventina valley, ticino trunk glacier was joined by ice draining blenio and moesa valleys. both tributaries were influenced by likely transfluences from the vorderrhein ice dome via lukmanier, cristallina and greina passes, as well as from the hinterrhein accumulation areas via san bernardino pass (fig. 2). right tributary glaciers of verzasca and maggia valleys fed the ticino glacier together with toce ice overflowing through centovalli valley. on the left side of the ticino valley, another diffluence existed over monte ceneri pass, draining ice directly to the south and towards lugano. in parts, these ice masses united with ice outflowing the adda glacier systems and terminated in the small ceresio lobe south of lake lugano (fig. 1; bini et al., 2009). through an overspill located near ponte tresa, some of the drained ice also re-entered the ticino catchment at valcuvia valley (bini et al., 2009) and merged with the united ticino-toce glacier at the western slope of the campo dei fiori (fig. 1, see fig. 6). advancing southwards, the large ticino valley glacier filled the overdeepened basin of lake maggiore (preusser et al., 2010) and merged with toce glacier coming in from the northwest. in its upper parts, the smaller toce catchment (~1800 km2) was dominated by ice draining through divedroand antigorio valleys, two tributary glaciers with additional linkage to the rhone glacier system adjacent the ticino-toce ice conveyor belts during the last glacial maximum 8 in the north (fig.1, fig. 2). the toce glacier system received overflowing ice from the rhone valley glacier via simplon pass and through a direct link to the rhone ice dome (florineth & schlüchter, 1998; kelly et al., 2004). an ice diffluence existed in the middle of the ossola valley, where ice of the toce catchment did overflow into the ticino catchment along the western vigezzo valley (a tributary of toce valley) and the centovalli valley (a tributary of ticino valley). right tributary glaciers of antrona and anzasca valleys joined the toce trunk glacier downstream. originating in the eastern slope of the monte rosa, ice outflowing anzasca valley represented the major tributary glacier. downstream from the anzasca confluence, one part of the toce glacier branched off to the south into the orta valley, building up the correspondent orta glacier lobe (~85 km2 in area) and a small morainic amphitheater (novarese, 1927; braakhekke et al., 2020). the main branch of the toce glacier, however, continued to the southeast to merge with the ticino glacier. downstream of the confluence at the gulf of borromeo, between stresa and verbania, the merged ticino-toce glacier filled the basin of lake maggiore and advanced several kilometers (about 28 km) towards the sse (fig. 1, fig. 2). the topographic control was reduced and the lgm ticino-toce piedmont lobe terminated on the plain. the bulbous terminus (known as verbano lobe) spread to cover ~380 km2 (kamleitner et al., 2022a). pre-lgm and lgm advances of the ticino-toce glacier built up a multi-ridged, closely stacked end moraine system, interlaced and succeeded by glaciofluvial plains (bini et al., 2014; piana et al., 2017; bernoulli et al., 2017; kamleitner et al., 2022a). the lgm maximum advances of both, orta and verbano lobes, were recently dated to ca. 25 ka and are interpreted to have been followed by a several thousand-year long period of glacier fluctuations near the maximum position (braakhekke et al., 2020; kamleitner et al., 2022a). late lgm readvances (~20-19 ka) were likely followed by rapid ice decay and retreat from the foreland (braakhekke et al., 2020; kamleitner et al., 2022a). the occurrence of large erratic boulders within the orta and verbano morainic amphitheatres was stated by several authors since the 19th century (omboni, 1861; gentilli, 1866; salmojraghi, 1882; sacco, 1892; cai, 1914). the biggest erratics were quarried for building purposes already in prehistory (de marinis, _______________________________ >>>>>> tab. 1 details of erratic boulders of the ortaverbano and ceresio systems lithologically analysed in this study. monegato g. et al. 9 2012) or used as holy sites (e.g. prea guzza). within the orta and verbano morainic amphitheaters, big boulders are not limited to the last glaciation, but were also found external to the lgm frontal moraines (braakhekke et al., 2020; kamleitner et al., 2022a). 3. materials and methods in the present work, provenance analysis was applied to erratic boulders found in the orta, verbano, and ceresio end moraine systems (fig. 1). the respective boulders were located during field campaigns related to different mapping and dating projects (bernoulli et al., 2017, 2018; braakhekke et al., 2020; kamleitner et al., 2022a). in total more than 500 erratic boulders were considered, out of which 105 boulders were chosen for provenance studies as their source rocks were well recognized (tab. 1). erratic boulders were grouped by their source rock on the base of the simplified geological map of the catchments, which derives from bigi et al. (1983), swisstopo (2005) and piana et al. (2017). more than 260 erratic boulders were located in the lower ticino and orta valleys, geographically positioned in a gis database and described in size and roundness type (tab. 1). most of the erratics are related to frontal or lateral moraine ridges but boulders situated on bedrock close to the trimline are also included (fig. 1). the size of the boulders varies from 1 m3 minimum to >300 m3 max (tab. 1, fig. 4). the exposure age of 54 erratic boulders was defined with cosmogenic nuclide exposure dating (braakhekke et al., 2020; kamleitner et al., 2022a). out of these, 19 boulders are related to the maximum advances and 31 located in the withdrawal moraines or in the valley floor. four boulders from the verbano end moraine system were dated to pre-lgm ice advance(s) (vr19, vr42, vr30 and vr45). four more boulders (gudo01, guer01, guer02, paru01) come from the lateglacial deposits in ticino valley. these eight boulders are included in table 1 but not considered in the discussion. a description of the boulder petrography was provided in the field. for 85 boulders (including exposure dated and other selected erratics), thin section analysis was performed in order to recognize the metamorphic facies of gneiss and micaschist lithotypes (fig. 5). an overall 289 erratic boulders related to the ceresio morainic amphitheatre were mapped and inventoried in a gis geodatabase during quaternary geological cartography for the sheet 152 mendrisio-como of the swiss geological atlas 1:25,000 (see bernoulli et al., 2017, 2018). 101 erratic boulders were considered as deposited during pre-lgm glacial advances, whereas 188 boulders are located within limits of the lgm expansion in the geological map (bernoulli et al., 2017). the eleven boulders included in the present work were lithologically recognized (tabs. 1 and 2) and, even if outside the mapped lgm (bini et al., 2014; bernoulli et al., 2017), they yield information about the flowline of this branch of the glacier. 3.1. provenance of the boulders the provenance of more than hundred erratic boulders related to the lgm of the orta, verbano, and ceretab. 2 overview of the geological units of the ticino-toce catchment and the provenance of the studied erratic boulders. the ticino-toce ice conveyor belts during the last glacial maximum sio glacier lobes, was identified using thin section analysis (85 samples) and visual interpretation in the field (30). the petrographic characteristics of the boulders are reported in table 2 and illustrated in fig. 6. boulders show petrographic provenance clustering in the wide area covered by the ticino and toce glacier snouts. an overall 48 samples are related to bedrock units located south of the insubric line, the sector closest to the glacier termini. the most frequently encountered lithologies are those related to the southalpine metamorphic basement (ivk and lam, with three boulders in the orta and 19 in the verbano system, respectively), the permian granites (gla, with three boulders in orta, ten in the verbano system, and one erratic in the ceresio end moraines, respectively) and the lugano volcanites (lv, two erratics in the verbano end moraine system). the occurrence of gla erratics was also documented in till north of sesto calende (omboni, 1861; salmojraghi, 1882). erratic boulders from the sesia-lanzo zone (sl) build a second important petrographic group, particularly in the orta end moraine system (seven boulders in the orta valley and three in the verbano system, respectively). mr and mo-cam-bel units are well represented in the orta system (eight samples), while one boulder (vr27, fig. 5h) was collected in the verbano area. ophiolitic boulders (antrona zone, aon) are present in both orta and verbano amphitheatres with two and seven samples, respectively. in the verbano end moraine system, erratics sourced from the antrona zone are widely scattered. aon erratics were found associated with lateral moraine deposits north of verbania (fig. 4e) and along the western margin of the former verbano lobe. three boulders sampled from verbano frontal moraines show aon signature. one of them (er192) is located 10 fig. 6 distribution and lithology of the studied erratic boulders in the orta-verbano and ceresio morainic amphitheaters. for color codes see legend of fig. 2. red crosses indicate areas where baveno granite boulders (gla unit) were recognized during railway constructions in the 19th century (omboni, 1861; gentilli, 1866; salmojraghi, 1882). mapped moraine ridges (bini et al., 2014; braakhekke et al., 2020; kamleitner et al., 2022a) are shown as red lines. distribution of glaciofluvial and glacial sediments was modified from the geological maps of piedmont (1:250,000; piana et al., 2017) and lombardy (1:250,000; montrasio et al., 1990) and the swiss geological atlas 1:25,000 (bernoulli et al., 2017, 2018). monegato g. et al. just south of lake varese. lower penninic boulders (lpn) are lacking in the orta amphitheatre while 15 and four lpn samples were collected in the verbano and ceresio end moraine systems, respectively. finally, one boulder of the helvetic gotthard massif was collected from monte pian nave (vr36; fig. 6), while one granodioritic boulder, coming from the bergell batholith (bg), was found south of lake varese. in the ceresio sector most of the boulders belong to the southalpine sedimentary covers (tab. 1, fig. 4f); because no local valley glaciers could have developed in the low-elevation sector, these boulders were transported by glacier diffluence. boulder lithologies indicate that both the ticino and the adda branches could have been responsible for erratic transport. as expected from the scarce mixing of the supraglacial fluxes, the distribution of analyzed erratic boulders shows an inhomogeneous lithological distribution. the lithotypes from bedrock of the ossola valley (aon, mr, ivk, sl) are largely distributed in the orta lobe and on the western side of the verbano lobe. nevertheless, erratics sourced from ossola valley were also found in the central part of the end moraine system, south of lake varese. on the other hand, lithotypes of bg, admg and hn, originating from the ticino valley network as well as lugano volcanites (lv) were found only in the very left sector of the verbano end moraine system. in contrast, the lower penninic bedrock (lpn) characterizes the upper catchments of ticino and toce glaciers. occurrence of penninic erratic boulders is common across the verbano lateral-frontal moraine complex. roundness of erratic boulders varies from angular to sub-rounded (tab. 1). most of the angular boulders are located on the outermost frontal and lateral moraines, while those located on internal moraines are mostly sub-angular to sub-rounded. an exception is represented by gla boulders that, despite their position, are mostly sub-rounded (fig.4c). this can be ascribed to the particular surficial exfoliation (ollier, 1967) of granite bedrock on the slopes of the mottarone (fig. 6) and the subsequent shaping during the transportation, even if from short distance. 11 fig. 7 flowlines of the ticino-toce glacier system (extent modified after bini et al. 2009, braakhekke et al., 2020, kamleitner et al., 2022a) during the lgm inferred from erratic boulder lithologies. dashed trajectories in the ceresio lobe are suggested by boulders located outside the pre-lgm limit (bini et al., 2014; bernoulli et al., 2017; no dates available). for symbols see legend of figure 6. the ticino-toce ice conveyor belts during the last glacial maximum 4. discussion 4.1. inferred ice flow paths in the ticino-toce system the distribution of index erratics within the orta, verbano, and ceresio end moraine systems found in this study can be coupled with observations made by early authors. the lithological provenance of granite and gneiss erratic boulders that have been subsequently removed by anthropogenic quarrying activities is reported by cai (1914). it is remarkable that omboni (1861) already noticed that the moraines west of lake maggiore are dominated by boulders of the toce catchment, while those close to the campo dei fiori slope (opposite, eastern side) are characterized by boulders of the inner ticino basement. baveno granite boulders (gla) are common in the lateral moraines (fig. 4b) of the western part of the verbano end moraine system deposited by the toce glacial branch at this point welded with the ticino glacier. however, baveno granite boulders, as well as the presence of this type of rock in lodgment till, were recognized in early excavations for the construction of a railway line between sesto calende and lake varese in the 19th century (i.e. in the eastern frontal sector of the verbano system; fig. 6; omboni, 1861; gentilli, 1866; salmojraghi, 1882). petrological investigations undertaken in this study and from the literature (omboni, 1861; gentilli, 1866; salmojraghi, 1882; cai, 1914) combined with exposure dating of selected erratic boulders and geomorphological analysis of earlier work (braakhekke et al., 2020; kamleitner et al., 2022a) yield crucial insights into glacier flow paths of the ticino-toce glacier during the lgm (fig. 7). boulder lithologies originating from the ossola valley indicate that the lgm orta morainic amphitheatre and the western section of the lgm verbano end moraine system correspond to the flow of the toce glacier. most of the boulders belong to the southalpine basement (ivk and lam), the permian batholith (gla), the sl and mr alpine nappes and the ophiolites (aon). it is remarkable that the inner sector of the toce catchment is scarcely represented in the orta moraines (braakhekke et al. 2020), whereas boulders of the lpn are common in the western frontal moraines of verbano (fig. 6), indicating a significant persistence of the dispersal train. boulders transported by the toce glacier are widely found on lgm lateral and frontal moraines of the verbano amphitheatre, including the sector south of lake varese. this suggests a dominance of the toce glacier over the ticino glacier. ticino glacier may have hence been confined to the eastern flank of the system (fig. 7). the toce system is characterized by a shorter stream course while at the same time being notably steep with accumulation areas reaching above 4000 m a.s.l. in comparison, the ticino catchment is more than two-and-a-half times the size of the toce basin, yet mountain peaks are lower, the slopes are gentler, and the thalweg is longer (fig. 3). an important divergence of the toce glacier was located along the vigezzo valley draining ice towards ticino valley and into high canobbina valley, as testified by glacigenic deposits (boriani & burlini, 1995); again this indicates the predominance of the toce glacier. these thoughts agree well with the palaeoglacier model by seguinot et al. (2018), which shows that the ticino glacier likely reached the mountain front slightly later, where it faced the physical obstacle of the spreading toce piedmont glacial lobe. likely due to ice congestion, flow of the ticino glacier was forced to diverge to the eastsoutheast across monte ceneri pass and to occupy the vedeggio and cassarate valleys (fig. 2). in the ceresio sector, it merged with the branch of the adda glacier system, coming through porlezza valley (bini, 1997; castelletti et al., 2014). the abundance of sedimentary rock boulders indicates that the ticino glacier eroded the sedimentary covers of the area and then formed the main part of the western ceresio lobe ending at arcisate. probably it made also a part of the eastern ceresio lobe, ending at stabio where it merged with the western part of the adda glacier system (bini, 1997; scapozza et al., 2014; bernoulli et al., 2018). in the lower reaches of ticino valley, a second divergence at luino may have promoted ice exchange between valcuvia valley and tresa valley. according to the distribution of erratic boulder lithologies in the orta, verbano, and ceresio end moraine systems, the major lgm ice streams of ticino and toce glaciers are suggested to have been as follows (fig. 7): the lgm orta glacier lobe was mainly fed by the anzasca tributary glacier (braakhekke et al., 2020) with a contribution of ice from the ossola/toce valley glacier in the eastern parts of the lobe. ice from the toce valley glacier built up the western sector of the lgm verbano glacier lobe and possibly extended far towards the southeast, at least during the early phase of the lgm. the ticino glacier dominated the eastern flank of the verbano system, in the lake varese and campo dei fiori sectors. through a diffluence across monte ceneri pass, ticino glacier fed western parts of the ceresio lobe between porto ceresio and arcisate. 4.2. implications for ticino-toce glacier dynamics the complex dynamics of the ticino-toce glacier network were strongly influenced by the asymmetry of the mountain catchments. a key role was played by the highest sector of the toce accumulation area represented by the high monte rosa fletschorn ridgeline, running over 3000 m a.s.l. with peaks over 4000 m a.s.l. the rapid spread of the toce catchment glaciers, taking into account the short travel distances (~100 km of the toce against ~150 km max of the ticino leventina, fig. 3), promoted early arrival of the toce glacier in the piedmont area. the possibly rapid response of the toce catchment to climate changes of mis 3 and the onset of the lgm supports the marked spread of toce ice over a large sector of the verbano piedmont lobe. presumably, the larger but slower ticino glacier was pushed to the east and forced to spread in the prealpine area of the lake lugano region. these results yield interesting implications for the reconstruction of the evolution and interconnections of large glaciated networks in mountain ranges. the fastest glaciers might have played a role in blocking the flow of glaciers with greater inertia and forced transfluences/diffluences if topography allowed 12 monegato g. et al. for it. during the lgm, the alps were covered by a network of interconnected valley glaciers (ivy-ochs et al., 2022). hence, many glacier systems were affected by merging trunk glaciers. the presented data from toce and ticino catchments underlines how the reaction time of neighboring glacier systems may vary due to inherent differences in catchment geometry, especially when the accumulation areas show a strong asymmetry. a similar behavior of ice overflowing into previously non-glaciated valleys forced due to blockage by another glacier was reported for trunk glaciers in the lower inn and salzach valleys (van husen, 2004; reitner et al., 2010), but can be conceivable in other sectors of the alps and in other mountain ranges as well. in addition, palaeoclimatic models suggest that precipitation was irregularly distributed in time and space across the alps contributing to anomalous ice accumulation throughout the lgm time bracket (kuhlemann et al., 2008; luetscher et al., 2015; del gobbo et al., 2022). moreover, the different distribution of major ice-flows can be related to how the accumulation areas, and specifically the major ice-domes, reacted to the climate change promoting the spread of the glaciers. according to modelling studies on the isere, rhone, and rhine paleoglaciers (coutterrand, 2010; jouvet et al., 2017; cohen et al., 2018), the contribution from different sectors of an accumulation area can be traced from the highest parts to the outlet. glacier simulations further suggest increased basal erosion underneath confluencing ice streams (cohen et al., 2018; jouvet et al., 2021). some valley reaches of the rhine catchment were characterized by very slow advance (cohen et al., 2018), and this characteristic may be inferred for the advance of the ticino glacier through the valley section south of bellinzona, which is up to 4.5 km wide with a very low gradient. the model of seguinot et al. (2018) shows that the toce glacier extended to gravellona toce several times already in the mis 4 and mis 3 cold phases and may have molded the valley outlet. on the other hand, the ticino glacier arrived in the lake maggiore area only during the lgm (seguinot et al., 2018), when the paleoclimatic conditions (del gobbo et al., 2022) allowed the spread of a large glacier and its persistence until the final collapse at about 18 ka (wirsig et al., 2016; ivy-ochs et al., 2022). moreover, the shallow elevation in the lower toce valley bottom and in the gulf of borromeo is in contrast to the deep trough of lake maggiore (cazzini et al., 2020) and may indicate a more effective subglacial carving by the ticino glacier. this may suggest that the toce glacier prevailed at the lgm onset and the ticino glacier at the lgm climax. 5. conclusions the study of the provenance of erratic boulders of the ticino-toce glacier system provides interesting insights into the development of a large lgm glacial network and its outflow in the prealpine and piedmont areas. the distribution of erratic boulders shows a dominance of the toce glacier in the orta lobe and in the western-central sector of the verbano lobe. the lgm orta lobe was predominantly fed by ice from anzasca valley, a right tributary glacier of the toce valley glacier. despite the much larger catchment, lithologies indicative of the ticino glacier are largely limited to the eastern sector of the lgm verbano lobe and the western parts of the ceresio system, where ticino ice merged with the westernmost branch of the adda glacier system. the topographic differences in the overall accumulation areas, with maximum elevations (>4000 m a.s.l.) and steep slopes in the toce catchment, promoted the sudden and rapid spread of the toce glacier, whose path was shorter (<100 km) in comparison to the ticino glacier (around 150 km). the early arrival of toce glacier possibly resulted in the damming of the ticino glacier and fostered the diffluence of ticino ice into the prealpine area to the east, merging with the western branch of the adda glacier, where elevations were too low for hosting independent valley glaciers during the lgm. the dynamics of the two studied lgm glaciers highlight the importance of topography as a driver for ice build-up and development of valley glaciers. faster glaciers may force slower trunk glaciers to a different path. considering the topographic setting of the alpine area this could have been a common phenomenon also in past glaciations. the provenance of boulders can thus provide an important tool for determining glacier flow trajectories that could have been affected by unequal glacier evolution. acknowledgments funding by the swiss national science foundation is gratefully acknowledged [snf grant number 175794, 2017]. the reviews provided by two anonymous reviewers greatly improved our manuscript. we also thank a. fontana (a.e.) for his comments. references baudin t., marquer d., persoz f. 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(2016) dating the onset of lgm ice surface lowering in the high alps. quaternary science reviews 143, 37-50. ms. received: october 27, 2022 revised: november 22, 2022 accepted: november 25, 2022 avaiable online: december 22, 2022 16 monegato g. et al. impaginato atti il quaternario italian journal of quaternary sciences 1155(1), 2002, 121-130 ppeeddoossttrraattiiggrraapphhiicc nnootteess oonn tthhee mmiiddddllee –– llaattee pplleeiissttoocceennee ooff ccaappoo ssaann vviittoo ppeenniinnssuullaa ((nnww ssiicciillyy)) aa.. ccoottttiiggnnoollii11,, gg.. bboosscchhiiaann22,, cc.. ddii mmaaggggiioo11,, ff.. mmaassiinnii11,, dd.. ppeettrruussoo11 1dipartimento di geologia e geodesia, università di palermo, corso tukory, 131, i-90134 2dipartimento di scienze archeologiche, università di pisa, via santa maria, 53 i-56100 pisa this work is supported by grants murst cofin 1997, "risposta dei processi geomorfologici alle variazioni ambientali" (nat. resp. a. biancotti, loc. resp v. agnesi) and by athenaeum grants of palermo university (ex 60%) to f. masini. abstract the available data about quaternary pedostratigraphic of north-western sicily are mainly obtained when fossil vertebrate assemblages are studied. these are often found in caves or in other morphological "traps", where the products of the erosion of soils developed outside these features are redeposited. soils that may have originated these deposits were found on the marine terraces that are typical of the coast areas of sicily. two sequences, called "k22" and "isolidda", that crop out in the north-western side of the san vito lo capo peninsula – to the west of palermo are examined in this work. the first one is a karstic cave infilling, situated near the eastern rim of the old falaise that borders the piana di sopra plateau. two phases were identified in this site. a) transitional environment deposits, with terrigenous input due to the occurrence of alfisols and/or ultisols in the neighbouring area. b) continental deposits, mainly made up of reworked terra rossa, that point to fluctuations of the erosive regime. the aeolian input can be observed throughout the sequence and is apparently stronger in the uppermost levels. this deposition ends at the end of the pleistocene. the second one is a thick sedimentary body that occupies a tectonic depression, near torre isolidda. this sequence is made up of alternating colluvia, éboulis ordonnés and palaeosols dating back to the late pleistocene. the aim of this study is to ascertain which environmental condition affected the deposition of the lithological units of these two sequences and to correlate them to the climatic phases of the middle-late pleistocene. the study of the macroscopic characteristics of the sequences has been carried out in detail with the help of soil micromorphological observations. riassunto le conoscenze pedostratigrafiche relative al quaternario della sicilia nord-occidentale sono legate essenzialmente allo studio delle associazioni fossili a vertebrati che sovente si rinvengono in grotte o in altre "trappole" morfologiche, all’interno delle quali sono stati trasportati e rideposti i prodotti dell’erosione dei suoli che si sviluppavano all’esterno. suoli che potrebbero aver dato origine a questi depositi sono stati segnalati sulle successioni di terrazzi marini che caratterizzano il settore costiero dell’isola. in questo lavoro si esaminano due successioni, denominate k22 e sezione 5 isolidda, affioranti nel settore no della penisola di san vito lo capo, ad ovest di palermo. la prima è costituita dal riempimento di un cavità carsica ubicata in prossimità del margine orientale della paleofalesia che borda il pianoro di piana di sopra; ivi sono state identificate due fasi: a) depositi di ambiente di transizione, con apporti terrigeni dovuti alla presenza di alfisuoli/ultisuoli nelle aree emerse circostanti. b) depositi continentali, costituiti prevalentemente da terre rosse risedimentate che indicano pulsazioni del regime erosivo; l’input eolico, presente in tutta questa fase, diviene più cospicuo nei livelli superiori. questa sedimentazione si conclude con la fine del pleistocene la seconda è un potente corpo sedimentario alloggiato in una depressione di origine tettonica, in località torre isolidda. qui si osserva una successione costituita da alternanze di depositi di colluvio, éboulis ordonnés e paleosuoli ascrivibile al pleistocene superiore. lo scopo di questo lavoro è di individuare le condizioni ambientali che hanno presieduto alla formazione degli orizzonti delle due serie stratigrafiche e di mettere in relazione questi ultimi alle fasi climatiche del pleistocene medio-superiore. a tal fine lo studio delle caratteristiche macroscopiche e la ricostruzione di dettaglio delle serie è stata integrata con i dati derivanti dall’analisi micromorfologica in sezione sottile. parole chiave: pedostratigrafia, quaternario, aree costiere key words: pedostratigraphy, quaternary, coastal areas 11.. iinnttrroodduuccttiioonn several sedimentary sequences containing soils, palaeosols and their relicts were preserved in the capo san vito peninsula, mainly in its western sector, because of the relative tectonic stability of this area. these sequences are mainly preserved within caves or in other morphological traps; they were shortly described by di maggio et al. (1999) in a previous work concerning the seven orders of marine terraces of the peninsula, and the fossil vertebrate assemblages which are frequently found within these sequences. (fig. 1) the aim of this note is to give further insight in the reconstruction of the middle–late pleistocene environmental conditions by a pedostratigraphic approach, highlighting the role of the climatic fluctuations in the change of the sedimentary and soil-forming processes. special emphasis is given to two of the outcropping sequences, which are reasonably thick and can be dated by their faunal content and/or through geomorphological evidences that can be correlated to the sequence of the marine eustatic fluctuations and to the oxygen stable isotope climatostratigraphy. (fig. 1). the lithological units (sensu orombelli, 1971) of the sequences are described according to the guidelines of sanesi (1977) and catt (1990), while the descriptive criteria adopted for the soil micromorphological features follow the standard proposed by bullock et al. (1985). the c/f limit is set to 10 mm in the soil micromorphological descriptions. 22.. tthhee ""kk2222"" sseeqquueennccee this 9 m thick sequence infills a karst cavity located on the eastern edge of an ancient wave – cut cliff contouring the wide abrasion surface of the 1st order terrace, called piana di sopra (fig. 2). a large part of the cavity, of its entrance and of its infilling, were destroyed by a quarry whose cut advanced parallel to the cliff, so that the original shape of the cave cannot be observed. apparently, the original entrance of the cavity was situated on the top of the abrasion surface, very close to where the edge of the terrace is now. however, the present-day morphology of the cliff and the occurrence of lithodomous borings and marine deposits in the bottom of the cavity show that a large side aperture was opened when part of the cave was destroyed by the progressing wave-cut cliff. the lower part of the sequence testifies to a phase of deposition in transitional and shallow sea environment. this phase was correlated to some high stand of the isotopic stages 15-13, that in some places abraded the 2nd order terrace (di maggio et al. 1999). the upper part was deposited in continental environment and the lithological units embed vertebrate remains that can be ascribed to two different faunal assemblages. the lower ones yielded a fauna that can be referred to the elephas mnaidriensis faunal complex of sicily, of late middle pleistocene to early late pleistocene age (8(?)/6 – 5a isotopic stages). the upper ones embed an assemblage documenting a younger dispersal phase of mammals from the italian peninsula (pianetti – castello faunal complex of sicily). this assemblage is dominated by the savii ground vole, a species with steppe mediterranean affinities, that, in this context, testifies to a dry climate phase of the last glacial cycle (isotopic stage 4). the sedimentary sequence is closed by an anthropised level containing late mesolithic to early neolithic cultural remains (tusa personal communication), which can be referred to the pleistocene–holocene transition. 122 fig. 1 capo san vito peninsula: location of the sites and distribution of the marine terraces. the heights of the terrace edges are reported in the legend. penisola di san vito lo capo: ubicazione dei siti e distribuzione dei terrazzi marini. le altezze del margine interno dei terrazzi di vario ordine è riportata in legenda. a. cottignoli et al. 22..11.. ggeeoommeettrryy ooff tthhee sseeddiimmeennttaarryy bbooddiieess.. the shape of the lithological units in the k22 succession is controlled by two main factors: a) the shape of the karstic dissolution cavity where the sediments were deposited and b) the strong erosion activity which took place throughout the depositional history of the site. the lower units are sub-horizontal layers probably separated by paraconformities, that fill up the funnel – like bottom of the cave. the units of the upper half of the sequence (from the top of the ‘upper conglomerate’ upwards) are limited by erosion surfaces apparently dipping towards the south; these erosion surfaces are often channel-shaped and sometimes marked by stonelines. therefore, these units are sometimes shaped as channels whose axes plunge from the overlying abrasion surface to the bottom of the cavity. 22..22.. pprrooffiillee ddeessccrriippttiioonn the sequence is made up of the following units, from the bottom upwards. a. ‘base’ unit. coarse rounded calcareous sandstone with some fine gravel (5-20 mm) and common remains of marine molluscs. few pinkish to light orange clayey matrix; strongly cemented. thickness 0 to 20-40 cm depending on the shape of the underlying limestone surface. this units lies on the karstified limestone of the bottom of the cave and fills up part of the fractures. b. ‘lower conglomerate’ unit. polygenic conglomerate, with fine gravel to cobble-size subrounded elements with some rounded and subangular ones; unsorted; skeleton-supported structure. the conglomerate elements, mainly the less rounded ones, show sponge (clionia) borings. light pinkish matrix, made up of few angular or subangular quartz elements and very few subrounded flint; common dark reddish clayey aggregates, siltto medium sand-sized, impregnated of iron oxides; the skeleton of these aggregates is few, made up of coarse silt to very fine sand with quartz, few chert and sparse muscovite flakelets. fine micritic cement, with common larger euedral crystals. a second phase of cementation, deposed coarse subedral sparite crystals within the largest pores. thickness 0-35 cm; sharp, subhorizontal, slightly undulating limit. this unit lies within the funnel-like bottom of the cave and is shaped like a subhorizontal layer whose sides are limited by a roughly conical surface. common marine molluscs (spondylus, jujubinus) and few fish bone fragments c. ‘pinkish sandstone’ unit. light pinkish grainstone, strongly cemented, with common centimetre-size pores; few skeleton, made up of subrounded to subangular pebbles (maximum diameter 5 cm). most of the grains are apparently more or less fragmented bioclasts, possibly vegetal remains in which faint traces of cellular features can still be observed. very few angular very fine silt-sized quartz elements. common subrounded to rounded clayey aggregates, without skeleton, impregnated by amorphous fe-oxides; their size varies from very fine to fine sand. medium sorting. fine sandy matrix, made up of micrite elements. sparitic cement, made up of small size anhedral elements. thickness 15-20 cm; sharp, subhorizontal and slightly undulating limit. the unit is lens-shaped, convex downwards. common darker or lighter layer-like bands, caused by enrichments or depletions of iron oxides originated by movements of the water table. few fish bone fragments. (fig. 6 e). d. ‘upper conglomerate’ unit. polygenic conglomerate (biomicrites, biosparites, micrites and "scaglia"), with fine gravel to boulder-size elements (0.2 to 70-80 cm), fining upwards, skeletonsupported structure, common simple packing voids. strongly cemented. the elements are mainly prolate or oblate, subrounded, and their major axes usually lie horizontally, sometimes imbricated. very few matrix, made up of sparse very fine sand-size quartz elements and clayey aggregates as in c). these aggregates are common at the bottom and at 123 fig. 2 stratigraphic profile of the k22 sequence. 1: mesozoic coralgal limestone; 2: base unit; 3: lower conglomerate unit; 4: pinkish sandstone unit, 5: upper conglomerate unit; 6: orange unit; 7: red unit and petrocalcic horizon; 8: blocks unit; 9: brown unit. colonna stratigrafica della successione k22. 1: calcari coralgali mesozoici; 2: unità base; 3: unità conglomerato inferiore; 4: unità arenaria rosata; 5: unità conglomerato superiore; 6: unità arancio; 7: unità rosso e livello petrocalcico, 8: unità blocchi; 9: unità bruno. pedostratigraphic notes on ... the top of the layer and give it a pinkish colour. cement made up of micrite, finely layered in the pores, sometimes alternating with fe-oxides; a second phase of cementation deposed coarse subhedral sparite coatings within some pores. thickness 2-2.5 m; abrupt, subhorizontal, flat limit, gently dipping towards the centre of the cave. this unit covers the underlying unit c) and partly lies on the limestone bedrock of the northern side of the cave. its thickness increases towards the south, as the limit dips towards this direction. common remains of small size hippopothamus cf. pentlandi. e. ‘orange’ unit. reddish (2.5yr 4/6 red) silty loam to silty clay loam; well developed fine granular structure, slightly cemented. few skeleton, made up of sparse subrounded (dissolution) gravel-size elements (maximum diameter 3 cm). the sand-size fraction is made up of angular to subrounded quartz (very fine to fine sand), subrounded chert (slightly coarser) few muscovite flakelets (silt), angular to subangular fragments of biomicrites ad sparites (medium sand to fine gravel). common clayey aggregates (pedorelicts, sensu brewer, 1964) subrounded to rounded (fine to medium sand) stained by fe-oxides, usually without skeleton, sometimes with evident traces of very fine convolute layering, low birefringence strial b-fabric. (fig. 6 f). another group of aggregates contain less clay and feoxides and embed some fine skeleton with the same characteristics of that of the matrix. few clay coatings with iron oxides, some carbonate concretions. stipple speckled and granostriated bfabric. thickness 25-35 cm; sharp, flat limit, gently dipping towards the centre of the cave. this lens-shaped unit may be the eroded remain of a layer partly interfingered with the upper part of d); nevertheless, it can be observed only in a small area at the centre of the excavation profile, so that its stratigraphic position is not perfectly defined. common pulmonate molluscs, vertebrates and small mammals (crocidura aff. esuae, leithia ex gr. melitensis, maltamys aff. wiedincitensis). f. ‘red’ unit. red clay loam to silty clay loam, colour 2.5yr 4/6 red to 2.5yr 3/4 dark reddish brown, well developed medium polyhedric (prismatic in the upper part) structure. few subrounded (dissolution) skeleton. the sandy fraction is fine to very fine, mainly made up of angular to subrounded quartz (very fine to fine sand), common chert (slightly coarser), common muscovite laminae, few feldspar (some plagioclases, one sanidine), pyroxenes and some fragment of microcrystalline lava. few pedorelicts, slightly different from the matrix, but somewhat richer in clay and fe-oxides; rounded, fine to coarse sand-sized. common carbonate nodular concretions, nodules of iron and manganese oxides. few "dusty" clay coatings. striated, granostriated and stipple speckled b-fabric. (fig. 6 g h). thickness 50-110 cm; clear, flat limit, shaped as a large and deep depression, possibly an erosion channel. as a consequence of this erosion surface, the horizon lies upon units d) and e). in the western part of the excavation profile, a strongly cemented, 30-40 cm thick lens-shaped sublevel can be observed; it partly overlies a stone line of angular elements that marks the base of the "red" unit and embeds a large block, probably a cave ceiling or wall breakdown. the cementation is due to large anhedral sparite crystals, often organised in dendritic structures, rather dusty for fe-oxides impurities. common remains of continental gastropods, amphibians, reptiles, birds, large and small mammals. the mammal assemblage belongs the elephas mnaidriensis faunal complex of sicily and includes the following taxa: crocidura aff. esuae, leithia ex gr. melitensis, maltamys aff. wiedincitensis, hippopotamus cf. pentlandi and sus sp. g. ‘blocks’ unit. reddish silty loam, colour 2.5yr 4/6 red, medium developed polyhedric aggregation. common limestone skeleton, poorly sorted to unsorted (elements from 1 to 60-70 cm), made up of angular, prolate to oblate elements whose surfaces are altered by dissolution. skeleton supported or sometimes matrix supported structure. the sandy fraction is made up of angular to subangular quartz (very fine to fine sand with frequent rounded coarse sand elements); common muscovite flakelets, few feldspar and sparse pyroxene. common fragments of flint and of cherty rocks (scaglia), subangular to subrounded (medium to coarse sand); frequent slabs of sparitic limestone (very coarse sand to very fine gravel). common clayey pedorelicts, with very few fine skeleton, impregnated by fe-oxides. very common nodular concretions made up of sparite crystals, of various size. clayey groundmass, with very low birefringence; stipple speckled to granostriated b-fabric. thickness 40-60 cm; abrupt limit, marked by a stone-line, gently dipping towards the east and shaped as a large and shallow erosion channel. common remains of pulmonate gastropods and of micromammals. the small mammal assemblage, dominated by the vole microtus (terricola) ex gr. savii, also includes apodemus cf. sylvaticus and crocidura cf. sicula, while sus scrofa e cervus elaphus cf. siciliae occur among large mammals. this faunal assemblage can be referred to the pianetti–castello faunal complex. h. ‘brown’ unit. silty loam to sandy silt loam, colour 5yr 3/3 dark reddish brown, massive, rather loose. few limestone skeleton, unsorted (elements up to 50-60 cm), slightly altered by dissolution and chaotically dispersed. sandy fraction mainly made up of angular to subrounded quartz (very fine to medium sand), with some larger rounded elements; common fine muscovite flakelets, frequent feldspar and sparse pyroxene. common fragments of flint and cherty rocks (scaglia), subangular to subrounded (medium to coarse sand); few limestone slabs, sparse, very fine, rounded lava fragments. few clayey pedorelicts, embodying very few skeleton, impregnated by fe-oxides; common sparite concretions of various size; very common fine fragments and flakes of amorphous organic matter, at various degrees of decay. clayey groundmass, with low birefrin124 a. cottignoli et al. gence and stipple-speckled b-fabric. thickness 20-50 cm; clear, wavy limit, shaped as a shallow erosion channel. common more or less fragmented bone, charcoal, marine molluscs (patella, trochus) flint artefacts; remains of microvertebrates, (microtus (terricola) ex gr. savii, crocidura cf. sicula) and macrovertebrates (sus scrofa, vulpes vulpes e cervus elaphus). skeletal remains of homo sapiens. the typology of the lithic assemblage and the occurrence of obsidian artefacts show that these cultural remains can be ascribed to the late mesolithic-early neolithic (pleistocene-holocene boundary). 22..33.. ddiissccuussssiioonn the lowermost levels of the sequence, up to the top of the ‘pinkish sandstone’ unit, were deposited in peculiar environmental niches connected to near-shore or reef environments, like pools at the base of the reef or conglomerate deposition areas on abrasion surfaces. a more or less substantial input of terrigenous sediments coming from the neighbouring emerged areas characterises these deposits of transitional environment. the units ‘base’ and ‘lower conglomerate’ testify to high energy depositional events in shallow sea environment (intertidal or submerged beach), as shown also by borings of clyonid sponges occurring on pebbles of the ‘lower conglomerate’. conversely, the sandy unit ‘pinkish sandstone’ represents a very low energy environment, where almost only biogenic clasts, possibly fragments of algae or marine vascular plants, were deposited. it is likely that this rather homogeneous sediment was originated by in situ growth and decay of biogenic concretions, while middle or low energy transport processes were very rare. some weak input of sediments from the emerged land into these near-shore sediments is suggested by the occurrence of pedorelicts probably originated from the colluvium of soils developed on the abrasion surface overlying the cave. as these pedorelicts are mainly made up of clay and iron oxides, it may be inferred that they came from medium to long evolution red soils (alfisols or ultisols), that develop in temperate to warm–temperate climates and that are present in the capo s. vito area. the origin of unit ‘upper conglomerate’ is strongly questionable (di maggio et al., 1999). the large size of the cobbles and the low matrix content point to a high energy environment; conversely, the fossil remains of hippopotamus cf. pentlandi found in this unit are rather well preserved, and suggest therefore a low energy depositional environment, or at least a short range transport. river deposition may possibly explain the removal of the fine grained matrix by low energy flow; however, this hypothesis looks rather unlikely because no hydrographic basins or river sediments were found in the surrounding area. the general features of the deposit may also indicate a marine origin. the ‘upper conglomerate’ could be considered as a beach or a storm deposit, implying that the shoreline was rather close to the site. the terrigenous fine-grained fraction and the pedorelicts would have infiltrated into the pores of the conglomerate after the deposition of the coarse fraction. in this case the conglomerate, with its mammal fossil content, would date back to one of the high stand phases related to the isotopic stages 15-11, according to di maggio et al (1999). however, this range of ages is in contrast with several data concerning the presence of the hippo in the sicilian island, which is usually dated to the late middle pleistocene to late pleistocene (isotopic stages 8 or 6 ?). finally, an alternative explanation in accordance with all the available data, and based on the parsimony principle, would consider the ‘upper conglomerate’ as derived from a pre-existing conglomerate, dismantled by gravitational processes and runoff water, which would also have caused the transport of the vertebrate remains into the cavity. the upper part of the sequence, from the unit ‘orange’ upwards, was deposited in continental environment. the characteristics of the deposits follow the polycyclic nature of the "terra rossa" and result from the erosion of the soils and the accumulation of the products of their reworking into the cavity. the occurrence of pedorelicts in all these levels is sound evidence of erosion and transport (cremaschi, 1990b; boschian, 1998), and their concentration may be regarded as a rough estimate of the intensity of the reworking processes. the greater amount of pedorelicts in unit ‘orange’ documents a period when erosion was stronger than in the other phases. apparently, the pedorelicts found in the upper units are not so rich in clay and iron oxides as those in the underlying ones, and also embody some fine skeleton. it is likely that the older ones belonged to more evolved soils, while less developed soils overlied piana di sopra during the younger phase of the site formation process. as a consequence, it may be inferred that strong erosion processes had removed most of the soil cover of the area in some moment between isotopic stages 15-11 and 8-6. nevertheless, the occurrence of several gaps in the sequence suggests caution in inferring this diachronic and evolutionary hypothesis. summing up, the evolution of the climate towards ‘continental’ conditions may have started some deforestation and the triggering of erosive processes that caused the accumulation of unit ‘orange’. unit ‘red’ may be related to a phase of weaker erosive processes, with climate not so strongly continental as before. the occurrence of muscovite flakes all over the sequence shows that the aeolian input, still important nowadays, played always a consistent role in the formation of the "terra rossa" deposits. however, it must be pointed out that the palaeoclimatic meaning of this aeolian input is certainly different from that postulated for the northern regions of the italian peninsula (cremaschi, 1990a), even if it points towards somewhat aridic conditions. nevertheless, the occurrence of rounded coarse quartz grains within the upper units ‘blocks’ and ‘brown’ may testify to an increase of the aeolian transport, which probably corresponded to dune formation in the neighbours of the site and might suggest a shift of the climate towards dry conditions. eventually, the ‘brown’ anthropic level is characterised by a high content in fine amorphous organic matter consequent to human presence. 125pedostratigraphic notes on ... 33.. tthhee ""iissoolliiddddaa"" sseeqquueennccee this sequence (fig. 3) is located in the northernmost part of a widely extended set of deposits that occupy a morphostructural depression shaped in "scaglia"–like marly limestone of upper cretaceous to eocene age. it is limited to the north by the southern side of the calcareous plateau of piana di sopra, and to the south (at seno del bue marino) by a morphological high originated by the denudation of a limestone olistolith embedded in the scaglia. the profile studied here is about 50m long and 11m high, with its bottom at the height of the presentday sea-level. the base of the sequence is made up of late pleistocene shallow sea and intertidal deposits (di maggio et al., 1999), and lies on a marine abrasion surface located at 0.5-1m a. s. l., that partially cuts the eutyrrhenian terrace (vi order); this terrace is here 3-5m a. s. l. high, and is covered by sediments containing a warm, "senegal–like" marine invertebrate fauna including patella ferruginea and strombus bubonius (at seno del bue marino; ruggieri et al. 1968; mauz et al., 1997) (fig. 4, 5). as a consequence, the formation of the isolidda abrasion surface is younger than the eutyrrhenian, and can be reasonably referred to high stands related to the isotopic substages 5c or 5a ("neotyrrhenian"). six subhorizontal or slightly dipping units can be observed within the continental part of the sequence, and are hereafter described from the bottom upwards. 33..11.. pprrooffiillee ddeessccrriippttiioonn a. ‘marine’ unit it is made up of two sub-units. 1) biocalcarenite with some reddish sandy loam matrix. 2) conglomerate made up of coarse limestone and marly limestone blocks with lithodomous borings and cemented sandy matrix (sandstone) with pebbles; the pebbles are rather common in the lower part of this subunit and form a thin level at the very bottom. thickness about 1.3 m, sharp limit situated at about 0 m a. s. l. 126 fig. 3 schematic section of the isolidda sequence. sezione schematica della successione isolidda. fig. 4 geomorphological map of the isolidda area. 1: slope deposits; 2: weathered and eroded scarp; 3: inactive marine cliff (height > 10 m); 4: inactive marine cliff (height < 5 m), 5: active storm ridge; 6: neotyrrhenian marine deposits; 7: neotyrrhenian marine abrasion surface, 8: eutyrrhenian marine deposits; 9: eutyrrhenian marine abrasion surface, 10: marine abrasion surfaces (late early pleistocene – middle pleistocene). carta geomorfologica dell’area di isolidda. 1: deposito di versante; 2: scarpata di morfoselezione degradata; 3: falesia inattiva; 4: ripa di erosione marina inattiva; 5: cordone di tempesta attuale; 6: deposito marino neotirreniano; 7: superficie di abrasione marina neotirreniana; 8: deposito marino eutirreniano; 9: superficie di abrasione marina eutirreniana; 10: superfici di abrasione marina del tardo pleistocene inferiore – pleistocene medio. a. cottignoli et al. this unit was deposited in infralitoral environment and is at present partly covered by recent storm deposits. shells of spondylus sp., pectinidae and helicoidal gastropoda are present. b. ‘transitional’ unit sandy loam, 2,5yr 4/6 red with white carbonatic mottles, massive structure. sandy fraction made up of quartz and feldspar grains, muscovite and biotite laminae, common limestone and some flint slabs. channel and chamber microstructure. common nodules of iron oxides, micrite hypocoatings and infillings, iron-stained clay coatings on the pedorelicts and on the coarse grains. frequent pedorelicts, whose matrix is made up of subangular quartz, impregnated by fe-oxides and with poroand granostriated b-fabric. frequent mollusc shells. (fig. 6 c). stipple-speckled b-fabric. thickness 30 cm, sharp subhorizontal limit. c. ‘fine breccia’ (b1) unit breccia, made up of fine (up to 3 cm) subangular elements and reddish sandy matrix. thickness 25 cm; sharp, slightly wavy subhorizontal limit. d. ‘red with blocky levels’ unit the bottom part of this unit is dark red (2.5yr 3/6) sandy loam; medium developed fine granular structure. the sandy fraction is made up of quartz, flint and limestone (biomicrite and grainstone). common iron and manganese aggregates; frequent calcite concretions, mainly micrite infillings and hypocoatings covered by sparite coatings; coatings and hypocoatings made up of iron oxides. stipple-speckled and sometimes poroand granostriated b-fabric. the middle and upper part is red clay loam, with poorly developed polyhedric structure. sandy fraction made up of quartz, glauconite, feldspar and muscovite flakelets. common and thick coatings made up of iron oxides. (fig. 6 b). stipple-speckled and sometimes poroand granostriated b-fabric. the most outstanding characteristics are the almost thorough decalcification and the rubefaction of the clay fraction of the groundmass. thichness 4.7 m; sharp subhorizontal limit. several subhorizontal levels of large blocks are interlayered within this unit. common bioclasts, mainly remains of continental molluscs, strongly altered. e. ‘yellow–brown’ unit sandy loam, yellow 10yr 8/6, with medium gravel-size skeleton, poorly developed granular structure, common pores. sandy fraction made up of flint and quartz and some feldspar grains, muscovite laminae; limestone slabs are common. common diffuse and nodular calcite concretions; sequences of micrite coatings/hypocoatings, clay coatings and coatings of acicular calcite. (fig. 6 a). frequent typic and nucleic nodules of fe-oxides. few charcoal and vegetal remains. abundant rounded to subrounded pedorelicts. stipple-speckled b-fabric, sometimes crystallitic in the upper part, where the groundmass is impregnated by micrite. thickness 2.40 m; sharp, subhorizontal erosive limit. several thin breccia levels, with medium to fine gravel elements testify to phases of increase in detritic input; an erosion surface can be observed in the lower part. at the top of the unit there is a hard petrocalcic horizon, 20-30 cm thick, with common shells of continental molluscs. common fragments of continental mollusc shells. f. ‘red–brown’ unit sandy loam with few subangular limestone and cherty slabs, reddish brown 2.5yr 4/4, poorly developed granular structure. the sandy fraction is made up of rounded quartz grains, feldspar, muscovite laminae and some glauconite grains. micrite and sparite coatings, (fig. 6 d), few coprolites; pedorelicts with quartz skeleton and few iron oxides; common nodules of fe-oxides. stipple speckled bfabric, sometimes poroor granostriated; in some areas the groundmass is impregnated by micrite. 127 fig. 5 panoramic view of the isolidda area. eu: eutyrrhenian abrasion surface; neo: neotyrrhenian abrasion surface; is.5: isolidda sequence. panoramica dell’area di isolidda. eu: superficie di abrasione eutirreniana; neo: superficie di abrasione neotirrreniana; is.5: successione isolidda. pedostratigraphic notes on ... 128 fig. 6 microphotographs of the thin sections. a) clay and micrite coatings on pedorelicts and limestone grains; xpl. b) sparite coatings and iron oxide coatings and ipocoatings on grains and simple voids. xpl. c) pedorelicts and marine mollusc shells. xpl. d) sparite capping on rounded quartz grain. xpl. e) calcareous bioclasts, embedded in microsparite/micrite groundmass; at left, an elongated fish bone remain. ppl, frame width 1100 mm. f) rounded pedorelict made up of clay and iron oxides and, with stipple speckled b-fabric. clayey groundmass, with fine sand to silt-size quartz grains. xpl, frame width 1100 mm. g) fragments of layered dusty clay coatings, embedded in sandy silt loam groundmass with fe-oxides. ppl, frame width 1100 mm. h) as before, xpl. microfotografie delle sezioni sottili. a) pedorelitti e clasti carbonatici con rivestimenti argillosi e micritici; xpl. b) rivestimenti di ossidi di ferro e sparite su clasti e pori; xpl. c) pedoreliti e resti di molluschi marini; xpl. d) rivestimento sparitico “a cappello” su clasto di quarzo arrotondato; xpl. e) bioclasti calcarei in matrice microsparitica/micritica; a destra, un frammento allungato di osso di pesce; ppl, larghezza dell’immagine 1100 mm. f) pedorelitto argilloso e con ossidi di ferro, b-fabric macchiettata. pasta di fondo argillosa, con granuli di quarzo delle dimensioni delle sabbie fini-limo. ppl, larghezza dell’immagine 100 mm. g) frammenti di rivestimenti argillosi impuri stratificati; pasta di fondo franco limosa con sabbia ed ossidi di ferro. ppl, larghezza dell’immagine 1100 mm. h) come sopra, xpl. a. cottignoli et al. thichness 1 m, sharp, subhorizontal limit. at the bottom, a thin blocky level can be observed. the top part of the unit is strongly cemented and covered by a pinkish calcite crust. g. ‘breccia’ (b2) medium to fine breccia (3-5 cm), made up of limestone and cherty elements, well sorted; few sandy loam reddish brown matrix, poorly cemented. thickness 0.7-1.5 m, abrupted limit. the top of the unit is reddish brown sandy loam with 12 to 15 cm cobbles, forming a continuous, about 50 cm thick horizon that covers the sequence. frequent fragments of shells of continental molluscs. 33..22.. ddiissccuussssiioonn as indicated by its field aspect and micromorphological characteristics, isolidda can be interpreted as a cyclic sequence of palaeosols developed on scree-slope deposits located in a morphological trap; different pedo–climatic conditions affected the formation of the units. the lowermost horizon of the sequence, i. e. the biocalcarenitic ‘marine’ unit, is covered by beach deposits representing the transition to fully emerged conditions (‘transitional’ unit ); soil forming processes affected the ‘transitional’ unit probably during a temperate climate phase, as shown by its colour, texture and pedofeatures that suggest the development of an illuviation horizon. the thin layer of angular pebbles (b1) overlying this unit may be interpreted as the effect of a cold climatic fluctuation, that caused the accumulation of coarse deposits and interrupted abruptly the soil forming processes. the following unit (‘red with block levels’) probably testifies to two climatic phases. during the first one, some climatic instability induced variously alternating deposition, soil-forming and erosion processes that built up a rhythmic interlayering of "stone lines" of cobbles and blocks with slightly pedogenised finer deposits. during the second phase, long lasting soil-forming processes acted on the stable surface of this deposit under temperate-wet pedoclimatic conditions. a red soil (now palaeosol) developed, affecting the whole unit. the unit (‘yellow–brown’) is divided from the underlying ‘red with block levels’ by a sharp erosional limit, and a secondary erosion surface can be observed within it. the overall aspect of this unit, in which some levels of chaotically arranged breccia are evident, points to a fast colluvium process that involved sediments coming from a landslide body located to the west of the outcrop. this hypothesis is corroborated by the occurrence of frequent pedorelicts and coarse coatings within this unit, as well as by the scanty evidence of soil forming processes. these processes are evidence of a renewed climatic instability phase, during which arid events characterised by high evapotranspiration rate caused the deposition of carbonatic concretions, culminating with the formation of a petrocalcic horizon at the top of the unit. this unit indicates a remarkable change in sedimentary and pedogenetic conditions with respect to the underlying units. within the third unit (‘red–brown’), the decalcification of detrital fraction and rubefaction of clays are weak, while a greater amount in rounded quartz grains indicates an increased aeolian input. pedofeatures like iron concretions are well developed and pedorelicts are common, showing that some weak soil forming processes and colluvium acted under probably temperate-cold conditions. the breccia levels, indicated as b1 and b2, located close to the bottom and to the top of the sequence, can be compared to the éboulis ordonnés resulting from strong physical weathering of rocks due to abrupt dry–cold climatic variations that have been reported in the late glacial sequences of north western sicily by agnesi (1989) and ulzega (1989). 44.. ccoonncclluussiioonnss in the north–western sector of the capo san vito peninsula, the formation of sequences of continental deposits, soils and palaeosols has been controlled by several interacting factors during the quaternary. the major role was played by the quaternary climatic fluctuations and related eustatic sea-level changes; the tectonic movements modulated role and intensity of the morphogenesis, thus affecting the development of the marine terraces and of the soils. as a consequence, soil evolution is typically polycyclic in this context. the resulting sediments and soils are characterised either by features that indicate climatic (and tectonic?) stability, or by colluvial and detrital components and by erosion surfaces that point to a highly dynamical environment. such an instability characterised mainly the climatic deterioration phases; in this southern area, the most relevant aspect of the climate cannot have been a "strong" decrease in temperature, as it was at higher latitude, but probably some sort of shift to continental characteristics of the environment. the isolidda sequence is the record of this evolution through the last ice age. the ‘marine’ unit at the base of the sequence covers the abrasion surface of the vii order terrace, which is of neotyrrhenian age (stage 5c/5a?), and was deposited during the last marine transgression, before the beginning of the first pleniglacial (stage 4). the beach deposit of the ‘transitional’ unit represents the ultimate emersion of the area; soil-forming processes acted on its top, apparently under temperate conditions, until a cool–dry event documented by the éboulis ordonnés (breccia level b1) interrupted the process. the thick deposit ‘red with blocky levels’ is the result of probably fast accumulation of fine sediments with coarse debris events, in a landscape with scant vegetal cover. strong pedogenesis acted on this deposit during a subsequent long-lasting temperate-humid climatic phase (stage 3?), favouring the formation of a poorly developed alfisol. a marked climatic deterioration originated the unit ‘yellow–brown’: fast erosive and depositional events alternated to weak soil-forming point to highly dynamic and unstable conditions, probably characterised by scant forest cover and contrasted seasons. later, the climate evolved towards cold–temperate conditions that favoured a weak pedogenesis, as documented by the unit ‘red-brown’, which is somewhat rubefacted (stage 2?). the gravelly levels (b2) at the top of the sequence 129pedostratigraphic notes on ... may be representative of late second pleniglacial–late glacial "cold" climatic phases, when éboulis ordonnélike deposits accumulated (stage 2-1?). traces of older soils are preserved on a wide relict of the i order terrace, which has been an isolated relief since its emersion. these relicts are mainly preserved within sequences deposited in caves, depressions and notches, like the site k22. here, they occur in the basal marine and transitional units of the sequence (‘base’, ‘lower conglomerate’, ‘pinkish sandstone’), and can be correlated to the isotopic stages 15-13. a drift towards a "continental" climate, which is supposed to have caused deforestation and the onset of erosive processes, would be indicated by the unit ‘orange’. the formation of this unit likely followed a long lasting phase of stable environmental conditions: the occurrence of abundant fragments of thick clay coatings (papulae sensu brewer, 1964), indicates that evolved soils (alfisols or ultisols, typical of long "interglacial" phases of temperate conditions) originated these pedorelicts. tentative correlations can ascribe the soil-forming phase to stage 7, while the following erosive phase may be related to glacial stage 6. the unit ‘red’ may have been formed during a period of climatic improvement, when the erosion was somewhat weaker; possibly an interglacial phase that can be tentatively correlated to the last interglacial (isotopic stage 5 s. l.). the occurrence of muscovite flakes throughout the sequence shows that the aeolian input played a consistent role in the formation of the deposits. nevertheless, the occurrence of rounded coarse-grained quartz within the upper units ‘blocks’ and ‘brown’ may point to an increase of the aeolian transport, which likely corresponded to dune formation in the neighbours of the site (agnesi et al. 1998; di maggio et al. 1999). a climatic shift towards dry conditions during stadial phases of the last glacial cycle may explain this phenomenon. these units are here tentatively correlated to the stages 3 or 2 (‘blocks’) and to the pleistocene-holocene transition (‘brown’). finally, it must be pointed out that the sequences are located on morphological highs or in other areas of strong morphogenetic energy, where stratigraphic gaps can develop easily. this peculiarity explains the shortness of the sequences, but also infers some incertitude in the interpretation. rreeffeerreenncceess agnesi v., 1989. levanzo. in "guida alle escursioni", gruppo nazionale geografia e geomorfologia, cnr, trapani 27 – 30 giugno 1989, 27 –32. agnesi v., macaluso t., masini f., 1998. l’ambiente e il clima della sicilia nell’ultimo milione di anni, in s. tusa (ed.) "prima sicilia, alle origini della società siciliana", vol. i, 31-52, ediprint, palermo. boschian g. (1998). middle pleistocene to early holocene infilling deposits of the trieste karst caves (north-east italy). xiii uispp congress, forlì (italy), september 8-14, 1996, vol. 1, section 3-paleoecology, subsection geoarchaeology, 383-386. brewer r., 1964. fabric and mineral analysis of soils. john wiley and sons, new york. bullock p., fedoroff n., jongerius a., stoops g., tursina t., babel u., 1985. handbook for soil thin section description, waine research publications, wolvehampton. catt j. a., (ed.), 1991. paleopedology manual. quaternary international, 6, 1-95. cremaschi m., 1990a. the loess in central and northern italy: a loess basin between the alps and the mediterranean region. in cremaschi m. (ed.) "the loess in central and northern italy: a loess basin between the alps and the mediterranean region", c.n.r., centro di studio per la stratigrafia e la petrografia delle alpi centrali. quaderni di geodinamica alpina e quaternaria, 1, 15-19. cremaschi m. (1990b). depositional and post-depositional processes in rock shelters of northern italy during the late pleistocene: their paleoclimatic and paleoenvironmental significance. quaternaire, 1990 (1), 51-64. di maggio c., incandela a., masini f., petruso d., renda p., simonelli c., boschian g., 1999. oscillazioni eustatiche, biocronologia dei depositi continentali quaternari e neotettonica della sicilia nord-occidentale (penisola di san vito lo capo trapani). il quaternario, 12 (1), 25-49. mauz b., buccheri g., zöller l. & greco a., 1997 middle to upper pleistocene morphostructural evolution of the nw coast of sicily: thermoluminescence dating and palaentological-stratigraphical evaluations of littoral deposits. palaeogeography, palaeoclimatology, palaeoecology, 128, 269-285. orombelli g., 1971, concetti stratigrafici utilizzabili nello studio dei depositi quaternari continentali, riv. ital. paleontologia stratigrafia, 77 (2), 265-291. ruggieri g., buccheri g., rendina m., 1968 – segnalazione di tirreniano fossilifero a trapani. riv. min. sic., 112 114, 1 4. sanesi g., 1977, guida alla descrizione del suolo. c.n.r., p. f. conservazione del suolo, pubbl. n° 11, firenze. ulzega a., 1989, san vito lo capo – piana di sopra macari, in guida alle escursioni, gruppo nazionale geografia e geomorfologia, cnr, trapani 27 – 30 giugno, 18 – 23. 130 ms. ricevuto marzo 2002 ms. received: march 2002 a. cottignoli et al. imp. bosi nnuuoovvii pprroocceeddiimmeennttii ccaarrttooggrraaffiiccii ppeerr iill qquuaatteerrnnaarriioo ccoonnttiinneennttaallee:: ll’’eesseemmppiioo ddeellllaa ccaarrttaa ggeeoollooggiiccaa ddeellll''aallttaa vvaallllee ddeellll''aatteerrnnoo ccaarrlloo bboossii11,, ppaaoolloo mmeessssiinnaa11 && mmaarrccoo mmoorroo22 1 istituto di geologia ambientale e geoingegneria del cnr via del fosso del cavaliere, 100 00133 roma e-mail: c.bosi@igag.cnr.it; p.messina@igag.cnr.it 2 istituto nazionale di geofisica e vulcanologia via di vigna murata, 605 00143 roma e-mail: moro@ingv.it. riassunto nell’ambito della cartografia geologica italiana del quaternario continentale i procedimenti più evoluti sono attualmente quelli utilizzati dal progetto per la nuova carta geologica d’italia, alla scala 1:50.000 (carg). l’innovazione più sensibile introdotta da questo progetto è rappresentata dall’adozione delle unità allo-stratigrafiche o delle unità a limiti inconformi (ubsu). alcune realizzazioni degli anni ’90 suggeriscono però la possibilità di altre innovazioni che riguardano il contenuto informativo delle carte, con particolare riguardo alla utilizzazione degli elementi geomorfologici. in alcune delle procedure finora adottate, questi elementi non sono, infatti, più aggiunti a quelli stratigrafici, ma sono integrati con essi in una prospettiva che tende a superare l’abituale separazione fra stratigrafia e geomorfologia. la carta geologica del quaternario dell’alta valle dell’aterno è stata realizzata con procedimenti che rappresentano una radicalizzazione di queste procedure, fino al punto di modificare la struttura delle unità di riferimento. infatti, quelle cartografate non sono più unità stratigrafiche, ma unità corrispondenti ad una integrazione di unità allostratigrafiche ed unità “morfosequenziali”, queste ultime intese come elementi di una sequenza di superfici fossili (di erosione o di accumulo). queste unità, definite come “unità allo-morfosequenziali” (uam), sono di regola delimitate inferiormente da una superficie d’erosione sepolta al disotto della unità allostratigrafica, e superiormente da una, o più, superfici relitte. la principale differenza con le usuali unità stratigrafiche è che mentre queste sono definite principalmente sulla base dei fatti deposizionali, le uam rappresentano in modo esplicito anche i fatti morfogenetici, perfezionando la definizione della successione di eventi che hanno dato origine all’evoluzione geologica dell’area. questa differenza presenta anche conseguenze sul significato delle superfici di discontinuità che delimitano le unità stratigrafiche: esse non sono più considerate come semplici elementi di separazione fra unità allostratigrafiche (o ubsu), ma come testimonianze di eventi morfogenetici ai quali viene assegnata una totale parità di rango con quelli deposizionali. nell’area rilevata sono state riconosciute numerose unità che sono state raggruppate in tre insiemi diversi e precisamente: (i) una successione cronologicamente ordinata di 8 unità allo-morfosequenziali e di 19 unità morfosequenziali rappresentate da superfici relitte; (ii) 6 unità morfosequenziali corrispondenti ad una successione terrazzata almeno in parte più antica della successione precedente; (iii) tre unità stratigrafiche delle quali non è stato possibile definire nel dettaglio i rapporti con la successione cronologicamente ordinata. tutte queste unità sono state indicate con numeri che esprimono la posizione cronologica relativa degli elementi costitutivi (litosomi e forme). in una situazione come quella della zona considerata, dominata dal progressivo incassamento di forme e litosomi la successione delle unità allo-morfosequenziali viene manifestamente a corrispondere alle tappe del progressivo approfondimento del reticolo idrografico. viene quindi ad essere avvalorata la spiccata valenza evolutiva della carta. altre innovazioni adottate nella realizzazione della carta riguardano le indicazioni geomorfologiche e gli elementi strutturali. per le prime si è preferito rinunciare alle indicazioni usualmente riportate nelle carte geologiche (orlo di terrazzo, dolina, ecc.) limitandosi a cartografare solo gli elementi geomorfologici di diretto interesse nei riguardi della ricostruzione degli eventi geologici succedutisi nell’area, rappresentati dalle superfici relitte. per gli elementi strutturali sono state fornite indicazioni sulla cronologia della deformazione e sulla fonte delle valutazioni. tenuto conto che l’alta valle dell’aterno rappresenta un campione significativo delle conche intermontane dell’appennino centrale, la procedura illustrata in questa nota sembra essere suscettibile di una applicazione non strettamente locale. la carta presentata in questa nota si può quindi intendere come una proposta da collocare nella prospettiva metodologica di un superamento degli attuali criteri cartografici per il quaternario continentale. abstract in the field of the italian geological cartography of the continental quaternary deposits at present the most advanced procedures are those used for the new italian geological map project on a scale of 1:50.000 (carg). the most noticeable innovation introduced by this project is represented by the adoption of allo-stratigraphical units or unconformity boundary stratigraphic units (ubsu). some accomplishments in the 90’s, however, suggest the possibility of other innovations that regard the informative content of maps, with a particular consideration to the use of geomorphological elements. in some of the procedures which until now have been adopted, these elements have in fact not been added to those stratigraphic, but have been integrated with a perspective that tends to exceed the usual separation between stratigraphy and geomorphology. the quaternary geological map of the upper aterno valley has been achieved with a process that represents a radical use of these procedures, to such a degree that it modifies the structure of the reference unit. in fact, those cartographed are no longer stratigraphic units, but units that correspond to an integration of allo-stratigraphic units and morphosequencial units, the last agreed to be elements in a sequence of relict surfaces (due to erosion or accumulation). these units, defined as “allo-morphosequencial units” (uam) are delimited lower down by an erosional surface buried below by the allo-stratigraphic unit and above by one or more relict surfaces. the main difference with the usual stratigraphic units is that while these are defined mainly on the basis of depositional events, the uam also represents in an explicit way the morphogenetic events, perfecting the definition of the succession of events that have given origin to the geological evolution of the area. this difference also has consequences on the importance of the erosionial surfaces (unconformity) that delimit the stratigraphic units: they are no longer considered as simple elements of separation between allo-stratigraphic units (or ubsu), but as evidence of morphogenetic events to which is assigned a completely equal rank, as for those depositional. in the surveyed area many units have been recognised which have been divided into three different groups, which are: (i) a chronologically ordered succession of 8 units allo-morfosequenziali and 19 morphosequential units represented by relict surfaces. (ii) 6 morphosequential units corresponding to a terraced succession which is at least in part older than the previous succession il quaternario italian journal of quaternary sciences 1166(1), 2003, 109-120 110 c. bosi, p. messina & m. moro 11.. pprreemmeessssaa la geologia del quaternario continentale e marino costiero1 presenta notoriamente aspetti particolari, quali la rapida variabilità delle litologie e degli ambienti di sedimentazione, la frequenza ed il tipo delle discontinuità stratigrafiche, la prevalente modesta entità degli spessori e la possibilità di scansioni cronologiche molto dettagliate. una buona carta geologica del quaternario presuppone quindi l’adozione di criteri specifici ed un dettaglio di rilevamento inusuale in altri ambiti. per inciso è da osservare che le procedure anche impegnative che possono derivare da questi vincoli sono ampiamente giustificate dal fatto che il quaternario continentale rappresenta il contesto geologico maggiormente interessato dagli interventi antropici; se si eccettua la costruzione di gallerie e, in parte, lo sfruttamento delle risorse naturali, quasi tutti questi interventi riguardano infatti, in modo più o meno diretto, terreni e fenomeni quaternari. malgrado queste circostanze la cartografia geologica in italia si è sviluppata in una prospettiva stratigrafico-strutturale poco attenta alle problematiche quaternarie, con risultati spesso decisamente discutibili. una valutazione al riguardo è quella espressa dall’aiqua (associazione italiana per lo studio del quaternario), fondata sull’analisi di circa 160 carte geologiche pubblicate fino ai primi anni ’90 (bosi e messina, 1993). l’analisi, svolta da un gruppo di lavoro apposito2, ha messo in evidenza che la maggior parte delle carte ufficiali fino a quel tempo prodotte presentava gravi carenze, derivanti principalmente dal modo inadeguato con cui era stata definita la stratigrafia dei sedimenti continentali e marini costieri; altre carenze riguardavano i riferimenti cronologici, i criteri di correlazione fra le unità stratigrafiche, i dati strutturali e la utilizzazione degli elementi morfologici. a questa situazione si è proposto di ovviare il progetto per la nuova carta geologica d’italia alla scala 1:50.000 (carg), varato alcuni anni or sono, che ha introdotto nei criteri di rilevamento per il quaternario sensibili innovazioni (cnr, 1992), la più importante delle quali riguarda l’adozione di unità stratigrafiche più idonee alle specificità del quaternario (unità allostratigrafiche ed unità a limiti inconformi, v. paragrafo seguente). le informazioni disponibili sui risultati finora ottenuti in questo ambito e le esperienze acquisite con altre carte realizzate negli ultimi anni indicano tuttavia che esistono ancora ampi spazi per approfondimenti metodologici. di qui l’opportunità di iniziative come il progetto “carte prototipali” fondato sulla collaborazione fra cnr e servizio geologico nazionale, nel cui ambito è stata realizzata la carta geologica del quaternario dell’alta valle dell’aterno. lo scopo che ci si è prefisso con la redazione di questa carta è quello di fornire un esempio di carta geologica che sviluppa i criteri del progetto carg, nel duplice senso di una maggior coerenza e di una aumentata valenza geologico-evolutiva. la maggior coerenza è stata ottenuta con procedimenti che cercano di superare il dualismo stratigrafia/geomorfologia riconducendo tutti gli elementi considerati alla comune radice geologica. questo obiettivo è stato ottenuto adottando unità sostanzialmente diverse dalle usuali unità stratigrafiche in quanto discendono da una stretta integrazione di elementi stratigrafici e geomorfologici. l’incremento della valenza evolutiva è stato ottenuto perfezionando la successione di eventi che sono alla base dell’evoluzione geologica dell’area, aumentando di conseguenza la scansione temporale delle valutazioni di cronologia relativa che ne possono derivare. scopo di questa nota è l’illustrazione del procedimento seguito, con particolare riguardo ai suoi aspetti concettuali e metodologici. informazioni più analitiche sulla stratigrafia e sull’evoluzione geologica dell’area sono riportate in un’altra nota (bosi et al., in stampa b). (iii) three stratigraphic units of which it has been impossible to define in detail its relationship with the chronologically ordered succession. all these units have been indicated with numbers that express the relative chronological position of the constituent elements (lithosomes and shapes). in a situation such as the one considered, dominated by the progressive embedding of shapes and lithosomes, the succession of the allo-morphosequential unit is revealed in correspondence to the progressive deepening phases of the hydrographic network. the distinct evolutionary valence of the map is therefore confirmed. other innovations adopted in the making of the map regard the geomorphological indications and the structural elements. for the first, the common indications usually referred to in the geological maps have been abandoned (terrace borders, dolines, etc.) limiting ourselves to cartographing only the geomorphological elements of direct interest in regards to the reconstruction of successive geological events in the area represented by relict surfaces. information on the chronology of the deformation and origin of the evaluation have been provided for the structural elements. taking into account that the upper aterno represents a significant sample of the intermountain valley of the central apennines, the illustrated procedure in this text does not seem to be susceptible to only a strictly local application. the map presented can therefore be considered as a proposal to be placed in a methodological perspective as a surpassing of the present cartographic criteria for the continental quaternary. parole chiave: quaternario, cartografia, conche intermontane. keywords: quaternary, cartography, intramountain basin. 1 nel seguito questo ambito sarà indicato semplicemente con il termine “quaternario”. 2 il gruppo era costituito da c. bartolini, a. bini, c. bosi, l. brancaccio, l. carobene, f. carraro, a. carton, g.b. castiglioni, n. ciaranfi, a. cinque, p. messina, m. panizza, a. sposato e a. ulzega. 22.. pprreecceeddeennttii mmeettooddoollooggiiccii i precedenti metodologici di maggior interesse nei riguardi della problematica affrontata in questa nota sono essenzialmente quelli contenuti in carte espressamente dedicate al quaternario, prodotte in italia nell’ultimo quindicennio. buona parte di queste carte sono state realizzate con le classiche metodologie fondate sulla litostratigrafia. un esempio, relativo ad un’area prossima a quella considerata, è la carta della conca di rieti (cavinato, 1993). nell’ultimo decennio si sono però diffuse anche procedure cartografiche diverse, fondate sulla adozione delle unità allostratigrafiche o delle unità a limiti inconformi, proposte dal progetto carg. si tratta notoriamente di due tipi di unità stratigrafiche analoghe, in quanto ambedue fondate su limiti corrispondenti a superfici di discontinuità; le differenze riguardano aspetti sostanzialmente formali, quali le caratteristiche di tracciabilità delle stesse superfici, e questioni di priorità terminologica. carte di questo tipo sono quelle dell’apparato glaciale dell’adda (cremaschi et al., 1994), la carta dell’astigiano di boano e forno (1999), la carta della zona del mandriosotto (bini et al., 2001), il foglio “susa” della nuova carta geologica d’italia (direttore del rilevamento delle formazioni superficiali, f. carraro) e la carta dei 111nuovi procedimenti cartografici ... laghi di cornisello della provincia autonoma di trento (rilevatori del quaternario, c. baroni e a. carton). altre carte sono state realizzate sulla base di unità stratigrafiche corrispondenti a singoli eventi sedimentari separati da fasi erosive o, comunque, da fasi di non sedimentazione. si tratta quindi di unità sostanzialmente equivalenti alle unità allostratigrafiche (o a limiti inconformi), in quanto anch’esse necessariamente delimitate da superfici di discontinuità. una carta di questo tipo, relativa ad una zona prossima a quella esaminata, è quella della conca di sulmona (miccadei et al., 1998), la cui struttura informativa può essere illustrata dallo schema dei rapporti stratigrafici contenuto nella carta (fig. 1). esistono poi numerose carte di impronta più decisamente geomorfologica. un esempio abbastanza tipico è quello fornito dalla carta di una parte del gruppo di brenta di petrucci e cavazzini (1992) che, in sostanza, è una carta geomorfologica arricchita da informazioni sulla stratigrafia delle successioni quaternarie. fra le carte di questo tipo per la zona appenninica è da ricordare quella della zona di amatrice di cacciuni et al. (1995) che, su campiture corrispondenti ad unità litostratigrafiche quaternarie, riporta un insieme di dati geomorfologici, fra i quali sono compresi anche i limiti di superfici relitte. orientata ad una maggiore integrazione fra elementi stratigrafici ed elementi geomorfologici è la carta fig. 1 schema dei rapporti stratigrafici della conca di sulmona (da miccadei et al., 1998). schema of the stratigraphic relationships of the sulmona basin (from miccadei et al., 1998). 112 dell’alta valle del volturno di brancaccio et al. (2000), fondata su unità morfo-litostratigrafiche (sensu bosi, 1989a). all’integrazione di elementi stratigrafici e geomorfologici sono ispirate anche altre carte, pubblicate alla fine degli anni ’80 e nei primi anni ’90, riguardanti l’area di montalto di castro (bosi et al., 1990), la conca di fossa (bertini e bosi, 1989 e 1993) e l’alta valle del sangro (galadini e messina, 1993). in queste carte gli elementi stratigrafici e geomorfologici sono rappresentati, rispettivamente, da unità stratigrafiche corrispondenti a singoli eventi deposizionali, e da superfici relitte di erosione o di accumulo; l’integrazione fra questi elementi è stata realizzata ponendoli tutti in un’unica sequenza temporale, sintetizzata in opportuni schemi esplicativi (fig. 2). in una zona come quella appenninica, nella quale l’evoluzione geologica quaternaria si è realizzata per erosione di zone in sollevamento, questi schemi permettono di dettagliare il progressivo approfondimento del reticolo idrografico, arricchendo la griglia temporale nella quale le diverse unità stratigrafiche devono essere collocate. una variante dello schema di figura 2 è quella proposta da basili e bosi (1996) che, sviluppando un precedente lavoro (bosi, 1989a) perfeziona l’integrazione stratigrafia-geomorfologia (v. anche carraro e ferrarino, 1981), considerando anche le superfici di erosione sulle quali si appoggiano le unità stratigrafiche; nel relativo schema morfologico-stratigrafico sono quindi presenti, ordinati in un’unica sequenza numerica, i prodotti degli eventi deposizionali ed erosivi testimoniati nell’area (fig. 3). 33.. mmeettooddii aapppplliiccaattii gli aspetti metodologicamente rilevanti dei criteri seguiti nella realizzazione della carta dell’alta valle dell’aterno sono quelli relativi alla tipologia delle unità utilizzate, alle informazioni geomorfologiche ed alle notazioni strutturali. la scelta delle unità da porre alla base del rilevamento è ispirata ad una radicalizzazione di quella integrazione di elementi geomorfologici e stratigrafici già perseguita in precedenti lavori, citati nel capitolo precedente (bosi, et al., 1990; bosi et al., 1989 e 1995; galadini e messina, 1993; basili e bosi, 1996; bosi e messina, 1997). l’unità di riferimento cartografico è infatti la “unità allo-morfosequenziale” (uam) definita come l’insieme di: una unità stratigrafica (ua), corrispondente al prodotto di una singola fase deposizionale ed assimilabile ad una “unità allostratigrafica” o “unità a limiti inconformi”3; le superfici di erosione e/o di accumulo che la delimitano, assunte come “unità morfosequenziali”4 (um). fig. 2 schema dei rapporti morfo-litostratigrafici della conca di fossa (da bertini e bosi, 1993, modificato). schema of the morpho-lithostratigraphic relationships of the fossa basin (modified after bertini and bosi, 1993). 3 come detto in precedenza i due termini siano sostanzialmente equivalenti nell’ambito della problematica che interessa: la preferenza al termine “allostratigrafico” in questa nota è legata solo a ragioni di semplicità verbale. 4 il termine “unità morfosequenziale” è stato proposto in bosi (1989a), per definire un elemento morfologico che fa parte di una successione cronologicamente ordinata di elementi consimili, evitando il termine “morfostratigrafico” (usato da altri autori) che rappresenta una dubbia commistione di concetti morfologici e stratigrafici. c. bosi, p. messina & m. moro 113 in una situazione, come è quella della zona studiata, nella quale i litosomi sono di regola progressivamente incassati l’uno nell’altro, ogni unità “allo-morfosequenziale” viene ad essere delimitata verso il basso dalla superficie d’erosione sepolta sulla quale giace l’unità allo-stratigrafica e, verso l’alto, da una o più superfici relitte. unità così definite configurano una perfetta parità di rango fra eventi erosionali ed eventi deposizionali, in una prospettiva che considera tanto gli uni quanto gli altri ugualmente determinanti nei riguardi dell’evoluzione geologica. questa parità ha anche risvolti concettuali in quanto cambia il modo di considerare le superfici che delimitano le unità stratigrafiche: l’identità di queste superfici non risiede più nel loro ruolo di limitare litosomi, ma nel fatto di rappresentare effetti di specifiche fasi morfogenetiche. e’ evidente che le unità allo-morfosequenziali non possono essere considerate unità stratigrafiche, ma si configurano come unità di rappresentazione cartografica corrispondenti agli effetti degli eventi deposizionali ed erosivi che hanno caratterizzato una specifica fase dell’approfondimento del reticolo. l’insieme delle “unità allo-morfosequenziali” può essere descritto con riferimento ad una successione unitaria, schematizzabile da un opportuno schema dei rapporti stratigrafico-morfologici (fig. 4). in questo schema possono trovare razionale collocazione anche unità morfosequenziali costituite da superfici relitte scolpite nel substrato pre-quaternario, che possono essere assimilate ad unità allo-morfosequenziali per le quali l’unità allostratigrafica abbia spessore nullo. per quanto riguarda le informazioni geomorfologiche riportate sulla carta, esse sono limitate a quelle relative a tutte le superfici relitte (d’erosione e di accumulo) osservabili nel paesaggio. non si è ritenuto opportuno riportare elementi geomorfologici diversi da queste superfici sostanzialmente per tre motivi distinti. il primo è la ovvia necessità di non complicare la carta con troppi graficismi. il secondo motivo discende dal fatto che molti dei dati geomorfologici abitualmente riportati nelle carte geologiche sono di fatto sovrabbondanti rispetto al contenuto informativo proprio di una carta geologica. nel caso di conoidi, morene, ecc. l’informazione geomorfologica aggiunge infatti ben poco ad una corretta informazione sulla litologia e sull’ambiente di sedimentazione5, mentre in altri casi (doline, dune, allineamenti di dune ecc.) le informazioni possono addirittura essere dedotte dalle carte topografiche al 25.000. fig. 3 schema morfo-litostratigrafico dell’area di monterotondo (da basili e bosi, 1996). morpho-litostratigraphic schema of the monterotondo area (from basili and bosi, 1996). 5 nel caso del conoide, ad esempio, una volta che esso sia rappresentato da un colore che ne esprima queste caratteristiche e ne precisi l’estensione, aggiungere il simbolo geomorfologico equivale di fatto a dire che un conoide ... ha la forma di un conoide. l’eventuale conservazione dell’abituale simbolo di conoide (come nella carta oggetto di questa nota) può avere una sua giustificazione solo come espediente per non cartografare il limite preciso dei sedimenti appartenenti al conoide. nuovi procedimenti cartografici ... 114 il terzo, e più importante, motivo è rappresentato dal fatto che le indicazioni geomorfologiche usualmente cartografate, configurano un set di informazioni avulso dal contesto stratigrafico-strutturale delle carte geologiche. si tratta infatti di indicazioni relative a forme presenti nel paesaggio attuale, senza che, di regola, ne sia indicata la collocazione cronologica, né i rapporti con le unità stratigrafiche riconosciute. seguire la prassi usuale equivale quindi a far coesistere due insiemi di informazioni sostanzialmente disomogene, a tutto scapito della struttura logica della carta. d’altra parte, anche l’eventuale precisazione in termini cronologici delle usuali notazioni geomorfologiche appare scarsamente soddisfacente. un esempio a questo proposito è quello del terrazzo il cui ciglio fornirebbe informazioni di fatto superate dalla rappresentazione cartografica della spianata sommitale del terrazzo. la delimitazione di questa spianata costituisce anzi un’informazione più completa dell’indicazione del ciglio del corrispondente terrazzo in quanto riguarda anche i casi di spianate prive di un ciglio morfologicamente definito. l’unico modo in cui la rappresentazione del ciglio fornirebbe informazioni più dettagliate sarebbe quello di rappresentare il ciglio come intersezione di una superficie sommitale con le scarpate che la delimitano, precisando l’età di ciascuna di esse; soluzione questa che risulta estremamente complessa e difficilmente realizzabile data la diacronicità delle scarpate. in relazione alle notazioni strutturali si è ritenuto utile inserire due informazioni, non considerate nelle usuali carte geologiche. la prima riguarda la cronologia della deformazione che è stata valutata in modo molto schematico, nei limiti concessi dalla situazione stratigrafico-strutturale dell’area cartografata. la seconda riguarda la fonte delle valutazioni cartografate e consiste nel mettere in evidenza quelle fondate su elementi decisamente interpretativi, quali le particolarità geomorfologiche potenzialmente riconducibili a dislocazioni tettoniche. 44.. iill qquuaatteerrnnaarriioo ddeellll’’aallttaa vvaallllee ddeellll’’aatteerrnnoo 44..11 lliinneeaammeennttii ggeeoollooggiiccii l’area cartografata si estende a w della catena del gran sasso, fra il versante sw del m. marine ed il margine ne del gruppo del m. giano. si tratta di un’area costituita da un substrato marino giurassico-miocenico variamente corrugato ricoperto da sedimenti continentali di varia facies ed età. i dati geologici disponibili per quest’area sono quelli riportati in bosi (1975), blumetti (1995), bagnaia et al. (1996), blumetti et al. (1996), basili et al. (1997), basili et al. (1999), messina et al. (2001) l’area è costituita da un importante fondovalle, che si evolve fino a divenire una ampia conca pianeggiante, e da un sistema di versanti calcareo-dolomitici (più raramente calcareo-marnosi) solcati da incisioni variamente pronunciate. in prossimità dei fondovalle sono estesamente presenti sedimenti fluviali, talora terrazzati, mentre sui versanti i sedimenti quaternari sono rappresentati solo da lembi di depositi di versante. l’area cartografata (figg. 5 e 6) rappresenta quindi un campione abbastanza significativo delle tipiche conche intermontane dell’appennino laziale-abruzzese. fig. 4 schema dei rapporti morfologico-stratigrafici dell’alta valle dell’aterno. schema of the morpho-stratigraphic relationships of the upper aterno valley. c. bosi, p. messina & m. moro 44..22 llaa ssuucccceessssiioonnee aalllloo--mmoorrffoosseeqquueennzziiaallee applicando la metodologia descritta nel capitolo 3, è stata delineata una successione di unità allo-morfosequenziali (uam), in ciascuna delle quali elementi stratigrafici ed elementi morfologici si integrano in vario modo. il limite inferiore di tutte le uam è costituito da una superficie di erosione scolpita in terreni di varia collocazione stratigrafica, in conseguenza del progressivo e costante incassamento dei litosomi l’uno nell’altro. questa superficie non ha una esplicita rappresentazione anche se è comunque definita nella carta; essa coincide infatti con il limite fra i colori delle diverse uam, corrispondente all’intersezione delle superfici d’erosione alla base delle diverse unità con l’attuale superficie topografica. il limite superiore di una uam può essere rappresentato dalla superficie di accumulo dell’unità allostratigrafica o da una spianata d’erosione che la tronca, o ad una combinazione delle due. come già detto in 3.3, nella successione allomorfosequenziale sono state inserite anche superfici relitte scolpite direttamente sul substrato, assunte come unità morfo-sequenziali. come si è già detto, queste unità, rilevanti in quanto testimonianze del progressivo approfondimento del reticolo idrografico, sono assimilabili ad unità allo-morfosequenziali per le quali la unità allostratigrafica abbia spessore nullo. la rappresentazione più indicativa della successione allo-morfosequenziale è quella dello schema dei rapporti morfologico-stratigrafici di fig. 4. in questo quadro seguendo la procedura già indicata in basili e bosi (1996) le unità stratigrafiche e le unità morfosequenziali sono state numerate progressivamente a partire dalla superficie di accumulo dei depositi alluvionali di fondovalle (1) alla superficie d’erosione alla base dell’unità stratigrafica più antica (27). a ciascuno di questi numeri è associata una sigla che chiarisce la natura del corrispondente elemento stratigrafico o morfologico (li=litosoma; se=superficie di erosione; sa=superficie di accumulo). questi numeri sono stati utilizzati anche per la denominazione delle diverse uam: ciascuna di queste unità è infatti definita da due numeri corrispondenti all’elemento (morfologico o stratigrafico) rispettivamente più recente e più antico fra quelli rappresentati nella stessa unità. si può far notare che questo tipo di denominazione ha il vantaggio di evitare il lungo elenco di termini (alloformazione o sintema o formazione di ….., superficie di …..) che sarebbe stato necessario adottare se si fosse applicata la usuale terminologia stratigrafica con i suoi riferimenti toponomastici; essa possiede inoltre una immediata evidenza in termini di cronologia relativa. complessivamente la successione allo-morfosequenziale è costituita da 27 (figg. 4 e 5) unità le cui caratteristiche sono sintetizzate in quanto segue, a partire dalla unità più antica. unità allo-morfosequenziale 26/27 l’ua 26 è costituita da conglomerati ad elementi carbonatici poco arrotondati e da alternanze di livelli ghiaiosi con ciottoli arenacei e calcarei e da livelli sabbioso-limosi. l'intera successione è basculata, con inclinazioni degli strati che raggiungano in alcuni casi i 20°. unità morfosequenziali 23-24-25 sono costituite da lembi di spianate di erosione rimodellate, scolpite su substrato e sviluppate a quote comprese tra 750 e 850 m. unità allo-morfosequenziale 21/22 l’ua 21 è costituita da ghiaie fluviali, talora sabbioso-limose, con elementi generalmente ben arrotondati (dimensioni variabili fino a 20 centimetri). localmente sono intercalati strati sabbioso–limosi con livelli ossidati probabilmente legati a variazioni del livello di falda. l’immersione della stratificazione varia tra s e w, con inclinazioni che raggiungono i 10°. l’embricatura dei ciottoli indica una direzione di trasporto da nw a se, mediamente parallela con il corso attuale dell’aterno. nella parte alta dell’unità è presente una superficie di erosione coperta da ghiaie fluviali appartenenti a successivi cicli sedimentari non distinguibili cartograficamente. unità allo-morfosequenziale 18/20 l’ua 19 è costituita da una successione di limi sabbioso-argillosi ben stratificati, a giacitura generalmente sub-orizzontale, a luoghi laminati, che rappresentano un deposito di fine ciclo fluviale passante verso l’alto ad ambiente lacustre. l’unità è delimitata a tetto dalla superficie di accumulo (um 18) ben conservata e riconoscibile a nw di barete a quota 780-800. unità morfosequenziale 17 e’ costituita da un insieme di lembi di superfici di erosione riconoscibili a nord di s. vittorino a quota 710800 m. le superfici, probabilmente riconducibili ad un episodio di spianamento sostanzialmente unitario, interessano in modo indifferenziato sia il substrato calcareo che l’ua 26 e l’ua 21. unità allo-morfosequenziale 14/16 l’ua 15 è costituita da un esiguo spessore (sino a 10 metri circa) di sabbie fini limose con rari ciottoli calcarei poco arrotondati. l’ambiente di sedimentazione è di tipo fluviale di bassa energia. l’unità è delimitata a tetto dalla corrispondente superficie di accumulo (um14) conservata in lembi rimodellati nella zona di cavallari. lateralmente um14 corrisponde ad una spianata di erosione che interessa sia il substrato calcareo che l’ua 21, ad una quota compresa tra 690 e 720 m circa. unità allo-morfosequenziale 11/13 l’ua 12 è costituita da livelli sub-orizzontali di ghiaie fluviali, variamente sabbiose, con elementi molto arrotondati, e da lenti di sabbie che contengono abbondante materiale di origine vulcanica (piccole scorie, pirosseni, biotite, ecc.). l’unità è delimitata a tetto dalla superficie di accumulo (um 11) conservata in lembi a quote 670-715 nella zona compresa tra prato lagone e prato dell’agora. unità morfosequenziale 10 e’ costituita da lembi di una spianata di erosione sviluppati a quote 665-675 e scolpiti sull’ua 12 nell’area compresa tra c.le visconti e pratiglio. 115nuovi procedimenti cartografici ... 116 fig. 5 stralci e legenda della carta geologica del quaternario dell’alta valle dell’aterno. la descrizione delle varie unità è riportata nel testo. base cartografica della regione abruzzo (aut. giunta reg. serv. inf. terr. e telem. prot. 2095 del 19/06/2003). parts and legend of the quaternary geological map of the upper aterno valley. see the text the description of the allo-morphosequential units. topographic map of the regione abruzzo. c. bosi, p. messina & m. moro unità allo-morfosequenziale 7/9 l’ua 8 è costituita da ghiaie sabbioso-limose fluviali ed è delimitata a tetto dalla superficie di accumulo (um 7) conservata in lembi a quote 670-680. unità allo-morfosequenziale 4/6 l’ua 5 è rappresentata da successioni limososabbiose con livelli di piccoli clasti sub-arrotondati ed è delimitata a tetto da una superficie, in parte di accumulo ed in parte di erosione (um 4), ben riconoscibile nella zona di scentella. unità allo-morfosequenziale 1/3 e unità allo-morfosequenziale 1/3 bis l’ua 2 è rappresentata da sedimenti fluviali sabbioso-ghiaiosi del fondovalle attuale e da coltri colluviali che ad esso si raccordano, nonché da depositi di versante e da depositi di conoide. l’unità è delimitata a tetto dalla superficie di accumulo (um 1), non cartografata, che corrisponde all’attuale fondovalle del fiume aterno. la successione allo-morfosequenziale descritta 117 fig. 6 ubicazione degli stralci cartografici di figura 5. location of the geological maps of figure 5. nuovi procedimenti cartografici ... non comprende tutte le unità stratigrafiche riconosciute: per mancanza di elementi di valutazione non è stato infatti possibile inserire esattamente in essa le “brecce di s. antonio”, le “brecce di s. marco” e l’ “allogruppo di arischia”. nell’allogruppo di arischia sono state incluse successioni litologiche di vario tipo (da limose a sabbiosoghiaiose) e di varia facies (da depositi di versante a sedimenti lacustri) sporadicamente conservate sul versante sinistro della valle. in queste successioni sono verosimilmente rappresentate più unità allostratigrafiche, delle quali non è però possibile indicare né le caratteristiche litologiche, né i loro reciproci rapporti. da segnalare anche che non è stato possibile precisare i rapporti fra la successione sopra delineata ed alcune unità morfosequenziali, rappresentate da lembi di spianate d’erosione molto rimodellate, osservate nella zona di cagnano amiterno. 44..33 rriiffeerriimmeennttii ccrroonnoollooggiiccii nell’area non sono state rinvenute faune o flore fossili di interesse cronologico. le valutazioni al riguardo sono quelle che possono essere indicate sulla base di alcune determinazioni 14c, di correlazioni a scala regionale e di misure di paleomagnetismo (bosi et al., in stampa a; messina et al., 2001). le determinazioni 14c riguardano le “brecce di s. antonio” per le quali sono state calcolate età calibrate di 31.710 ± 760 e 23.330 ± 300 anni bp (galadini e galli, 2000). le correlazioni a scala regionale inducono ad attribuire la ua 26 al più antico degli eventi deposizionali continentali noti, riferito ad un generico pliocene (primo evento deposizionale di bosi e messina, 1991; bosi et al., in stampa a). sulle stesse basi le ua 21 e 19 possono essere correlabili con il secondo e terzo evento deposizionale riferibili rispettivamente al pleistocene inferiore ed al pleistocene medio (bosi et al.; in stampa a). queste correlazioni sono in varia misura avvalorate da determinazioni di paleomagnetismo (messina et al., 2001) che indicano per la ua 26 una polarità normale riferibile ad una età maggiore di 1.170 ka, per la ua 21 una polarità inversa (matuyama) e per la ua 19 una polarità diretta (bhrunes). le “brecce di s. marco sono verosimilmente correlabili con le “brecce di f. vedice” (bosi, 1989b; bertini e bosi, 1989) e con le “brecce di bisegna” di bosi e messina (1990) che rappresentano un importante riferimento per tutto l’appennino laziale-abruzzese (bosi e messina, 1990; bosi e messina, 1991; bosi et al., 1995; bosi et al., in stampa, b) le determinazioni di paleomagnetismo confermano questa attribuzione, peraltro già avvalorata con lo stesso metodo da d’agostino et al. (1997). 44..44 eelleemmeennttii ssttrruuttttuurraallii coerentemente con il tema della carta sono stati cartografati solo gli elementi strutturali ad attività quaternaria considerati nella prospettiva delineata nel capitolo 3. tenuto conto di questa prospettiva e delle caratteristiche dell’area cartografata le faglie sono state classificate nel modo seguente: faglie ad attività documentata almeno sino alla parte alta del pleistocene superiore e loro ipotetici prolungamenti; faglie ad attività genericamente quaternaria e loro ipotetici prolungamenti; faglie probabili ad attività quaternaria, desunte solo da elementi morfologici. la faglia più importante è quella al piede del versante sw di m. marine che ha come espressione morfologica alcune evidenti scarpate di faglia che interessano anche terreni deposti in tempi storici (moro et al., 2002). un’altra faglia è quella presente lungo la direttrice s. marco s. vittorino che disloca le brecce di s. marco; essa costituisce il prolungamento verso nw della importante faglia del m. pettino la cui attività, al di fuori dell’area rilevata, si estende almeno fino al pleistocene superiore (galadini, 1999). altre piccole faglie sono quelle cartografate a ne di san vittorino, dedotte solo dalla presenza di alcune deboli e larghe depressioni ragionevolmente non riconducibili a fenomeni puramente erosivi. l’esistenza di queste faglie è stata di conseguenza ritenuta solo probabile. altre faglie di attribuzione incerta sono quelle osservate in una cava a w di cona della croce, non cartografate per la modesta entità del rigetto (pochi decimetri). altri elementi strutturali sono rappresentati da basculamenti nei depositi della ua26 a nord ed a ovest di barete. nella zona a sud della stessa località, la superficie um17 presente a tetto di ua21 è stata probabilmente basculata verso sse, in direzione cioè della zona di massima apertura del bacino di arischia. 55.. ccoonnssiiddeerraazziioonnii ccoonncclluussiivvee la carta geologica dell’alta valle dell’aterno è stata realizzata sulla base di criteri che corrispondono ad una radicalizzazione di alcune proposte metodologiche già pubblicate in precedenza, ispirate ad una stretta integrazione di informazioni stratigrafiche e geomorfologiche. questa integrazione è stata realizzata adottando particolari unità di riferimento, rappresentate da “unità allo-morfosequenziali” assunte come unità cartografiche a carattere misto, stratigrafico-morfologico, e, talora, da “unità morfosequenziali” rappresentate da superfici d’erosione relitte scolpite sul substrato, concettualmente riconducibili alle prime. queste unità non si configurano come unità stratigrafiche, ma come unità di rappresentazione cartografica, corrispondenti a particolari insiemi di elementi stratigrafici (unità allostratigrafiche o a limiti inconformi) e geomorfologici (superfici di erosione e di accumulo). e’ da osservare che in queste unità le superfici di erosione non sono più considerate solo come limiti di unità stratigrafiche, ma come effetti di specifici eventi geologici. nel caso dell’area in esame, caratterizzata dal progressivo incassamento di forme e litosomi, questi insiemi corrispondono alle principali tappe del progressivo approfondimento del reticolo che ha dato origine al paesaggio attuale. l’adozione di unità così definite sembra quindi avere una più spiccata valenza nei riguardi della ricostruzione dell'evoluzione geologica in tutti i suoi diversi aspetti. una delle differenze fra la carta così ottenuta e le 118 c. bosi, p. messina & m. moro usuali carte geologiche risiede nel fatto che le informazioni morfologiche non sono semplicemente aggiunte a quelle stratigrafiche, ma integrate con esse, in una prospettiva che considera in modo del tutto paritario fatti deposizionali ed erosivi, con tutti i loro effetti morfogenetici. questa integrazione, oltre a delimitare le superfici relitte, ne specifica infatti la collocazione cronologica relativa e ne precisa i rapporti genetici con le unità stratigrafiche ad esse sottostanti. di conseguenza, viene a cambiare la stessa struttura informativa della carta geologica. mentre le carte usuali corrispondono in sostanza ad una zonazione riferita ai prodotti degli episodi deposizionali (o comunque litogenetici) che si sono succeduti nel tempo, sulla quale sono sovrapposte notazioni geomorfologiche relative a forme riconoscibili nel paesaggio attuale, la carta oggetto di questa nota propone una zonazione riferita ai prodotti di particolari insiemi di eventi deposizionali ed erosivi, corrispondenti a diverse fasi dell’evoluzione geologica. e’ da osservare che la procedura adottata sembra fornire una adeguata soluzione al problema, formalmente ancora irrisolto, del rapporto fra dettaglio delle scansioni stratigrafiche e scala della carta. si tratta di un problema che viene affrontato secondo criteri propri delle diverse scuole. in qualche caso la soluzione viene ottenuta in modo riduttivo adeguando semplicemente le scansioni stratigrafiche alla scala della carta, nel senso che la scansione è tanto minore quanto minore è la scala. gli inconvenienti che possono derivare da una soluzione di questo tipo sono rappresentati sia dalla difficoltà di confrontare carte di operatori diversi e sia, soprattutto, dalla impossibilità di ricavare ricostruzioni dettagliate dell’evoluzione geologica quaternaria. una soluzione più soddisfacente è invece quella che nasce dalla applicazione che è stata fatta in relazione alle unità allostratigrafiche. se, come nel caso della carta in esame, queste unità si riferiscono al prodotto di un singolo evento deposizionale, il problema di restituire alla scala della carta i risultati ottenuti si riduce di fatto a quello di distribuire in gruppi le unità individuate, operazione che può essere eseguita con varie modalità senza nulla togliere alle conoscenze che vengono espresse nella rappresentazione cartografica. la zona alla quale è stata applicata la metodologia cartografica descritta può essere considerata sufficientemente rappresentativa di tutta la parte assiale della catena appenninica nella quale i litosomi quaternari sono tutti continentali e, di regola progressivamente incassati l’uno nell’altro. l’eventuale estensione del procedimento ad aree geologicamente diverse, quali le fasce periappenniniche nelle quali sono presenti anche successioni quaternarie di ambiente marino, non dovrebbe porre particolari problemi. dovrebbe infatti essere sufficiente ammettere che le unità allo-morfosequenziali possano avere una struttura più complessa, rappresentata ad esempio da più unità allostratigrafiche sovrapposte e da unità morfosequenziali interne alla successione stratigrafica. 66.. bbiibblliiooggrraaffiiaa bagnaia r., blumetti a.m., de luca g., gorini a., marcucci s., marsan p., milana g., salvucci r. e zambonelli e. 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(1994) montagna e pianura: i processi geologici recenti e gli effetti sull'ambiente. in: storia economica e sociale di bergamo: i caratteri originali della bergamasca. fondazione per la storia economica e sociale di bergamo. istituto di studi e ricerche, 109 –135. d'agostino, n., speranza, f. e funiciello, r. (1997) le "brecce mortadella" dell'appennino centrale: primi risultati di stratigrafia magnetica. il quaternario, 10 (1), 385-388. galadini f. (1999) pleistocene change in the central apennine fault kinematics, a key to decipher active tectonics in central italy. tectonics, 1188, 877-894. galadini f. e galli p. (2000) active tectonics in the central apennines (italy) – input data for seismic hazard assessment. natural hazard, 2222, 225-270. galadini f. e messina p. (1993) stratigrafia dei depositi continentali, tettonica ed evoluzione geologica quaternaria dell'alta valle del f. sangro (abruzzo meridionale). boll. soc. geol. it., 111122, 877-892. messina p., moro m. e speranza f. (2001) primi risultati di stratigrafia magnetica su alcune formazioni continentali dell'alta valle dell'aterno (italia centrale). il quaternario, 1144, 167-172. miccadei e., barberi r. e cabinato g.p. (1998) la geologia quaternaria della conca di sulmona (abruzzo, italia centrale). geologica romana, 3344, 59-86. moro m., bosi v., galadini f., galli p., giaccio b., messina p. e sposato a. (2002) analisi paleosismologiche lungo la faglia del m. marine (alta valle dell'aterno): risultati preliminari. il quaternario, 1155, 267-278. petrucci f. e cavazzini r. (1992) il quaternario del trentino sud-occidentale. i carta geomorfologica e dei depositi quaternari tra la val rendeva e cima tosa castel dei camosci (gruppo di brenta). il quaternario, 55(2), 163-172. 120 ms. ricevuto il 14 marzo 2003 testo definitivo ricevuto il 13 maggio 2003 ms. received: march 14, 2003 final text received: may 14, 2003 c. bosi, p. messina & m. moro imp.centamore eelleemmeennttss ttoo ccoorrrreellaattee mmaarriinnee aanndd ccoonnttiinneennttaall sseeddiimmeennttaarryy ssuucccceessssiioonnss iinn tthhee ccoonntteexxtt ooff tthhee nneeootteeccttoonniicc eevvoolluuttiioonn ooff tthhee cceennttrraall aappeennnniinneess eerrnneessttoo cceennttaammoorree11,, ffrraanncceessccoo ddrraammiiss22,, ggiiaannddoommeenniiccoo ffuubbeellllii22,, ppaaoollaa mmoolliinn22 && sstteeffaanniiaa nniissiioo33 1 università degli studi di roma “la sapienza”, dipartimento di scienze della terra, piazzale a. moro, 5 00100 roma 2 università degli studi “roma tre”, dipartimento di scienze geologiche, largo san leonardo murialdo, 1 00146 roma 3 dipartimento dei servizi tecnici nazionali, servizio geologico, via curtatone, 3 00185 roma abstract the central apennines show geologic and geomorphic features that report the strong influence of extensional tectonics and regional uplift on their recent evolution. the goal of this paper is to find out the time constraints of the chain uplift, focusing on the elements of correlation between marine and continental successions on both the adriatic and tyrrhenian sides. all along the range, the most ancient landforms are gently rolling or flat summit surfaces. on the tyrrhenian side, the interaction between the chain uplift and the extensional tectonics related to the opening of the tyrrhenian basin, generated several neoautoctonous basins that are older in tuscany (since the tortonian) and younger in the latium-abruzzo area (since the pliocene). on the adriatic side, the combined action of uplift and climatic changes, produced several depositional sequences, separated by angular unconformities. in the western basins, progressively coarsening upward sediments, corresponding to the globorotalia crassaformis biozone, are found. at valle ricca, in the upper section of these deposits, a 2.1 myr old volcanic layer, corresponding to the base of the globorotalia inflata biozone, is present. the valle ricca succession is truncated by an erosion surface over which marine and brackish sandy clay (argille sabbiose del chianitevere) lay down. similarly, in the periadriatic basin, a volcanic layer, dated 2.1 myr, has been found at bellante, in the upper part of a pelitic sequence. an angular unconformity separates this sequence from overlaying conglomerate and sand, recording a progressively eastward shifting of the coastline as a consequence of the uplift. contemporaneously, extensional tectonics progressively affected the apennine chain giving rise to a number of intermontane depressions, within which coarse breccia and lacustrine-alluvial deposits were deposited. in the rieti and l’aquila basins, the finding of equus stenonis and mammuthus meridionalis refer the basal part of these deposits to an age not older than the lower pleistocene. around 0.8 myr b.p., in correspondence with a base level drop induced by a sudden increase of uplift rate, the coastline rapidily shifted seawards and littoral sandy-pebbly sediments were deposited along both sides of the apennines. contemporaneously, increased stream erosion rates gave rise to the present valley network, within which the interaction of river incision and climate changes generated several orders of alluvial terraces. in this contest, a hunched backward river erosion breached most of intramontane depressions, draining off the lakes and causing the erosion of the basin sedimentary sequence. in conclusion, according to all these considerations, we hypothesize that the topographic growth of the range was slow until the end of the lower pleistocene, when a strong increase of the uplift rate affected the chain and the surrounding coastal belts. riassunto l’appennino centrale presenta caratteri geologici e geomorfologici che documentano l’intensa influenza della tettonica estensionale e del sollevamento regionale sulla sua evoluzione recente. in questo lavoro si intendono evidenziare gli elementi di correlazione tra le successioni marine e continentali della fascia periadriatica abruzzese e peritirrenica laziale, al fine di proporre dei vincoli temporali all’evoluzione recente dell’appennino. gli elementi geomorfologici più antichi, riscontrabili lungo tutta la catena appenninica, sono rappresentati da superfici sommitali gentilmente ondulate o pianeggianti. sul versante occidentale la tettonica distensiva legata all’apertura del tirreno ha generato una complessa serie di bacini neoautoctoni più antichi in toscana (dal tortoniano) e più recenti nell’area laziale (dal pliocene). sul versante adriatico il sollevamento della catena ha dato origine a discordanze angolari che individuano numerose sequenze sedimentarie in assetto monoclinalico. sul versante tirrenico della catena, si depositano sedimenti progressivamente più grossolani riferibili alla fine della biozona a globorotalia crassaformis. in particolare, a valle ricca, al tetto di questi depositi e alla base della biozona a globorotalia inflata, è stato trovato un livello vulcanico datato 2.1 ma. su tale successione si appoggiano in discordanza le “argille sabbiose del chiani-tevere” di ambiente marino e salmastro. similmente, sul versante adriatico, presso bellante, è stato rinvenuto un livello vulcanico datato 2.1 ma nella parte superiore di una sequenza di depositi pelitici. questa è troncata al tetto da una discordanza angolare che la separa da sedimenti conglomeratici e sabbiosi. contemporaneamente, la tettonica estensionale interessa progressivamente la catena generando una serie di bacini intermontani, delimitati da faglie normali. i materiali di riempimento sono costituiti alla base da sedimenti grossolani che passano verso l’alto a depositi alluvionali e fluvio-lacustri. nelle conche di rieti e de l’aquila il ritrovamento di equus stenonis e mammuthus meridionalis consente di riferire la parte basale di questi sedimenti ad un’età non più giovane del pleistocene inferiore. intorno a 0.8 ma b.p., in concomitanza con un forte abbassamento relativo del livello di base, legato ad un subitaneo incremento del tasso di sollevamento, si verifica un più marcato avanzamento delle linee di costa, accompagnato dalla messa in posto di depositi sabbioso-ciottolosi di ambiente litorale lungo i margini occidentale e orientale dell’appennino. contemporaneamente, un aumento del tasso di incisione fluviale dà origine all’attuale sistema di valli, all’interno delle quali, per effetto dell’interazione tra l’aumento dell’erosione fluviale e le variazioni climatiche, si sono formati più ordini di terrazzi alluvionali. in tale contesto, l’erosione regressiva dei corsi d’acqua ha profondamente inciso le soglie della maggior parte dei bacini intermontani, prosciugando i laghi ed erodendo gran parte dei depositi presenti. in conclusione, in base a queste considerazioni si può ipotizzare che la crescita topografica della catena appenninica è stata lenta fino alla fine del pleistocene inferiore, quando si è verificato un forte incremento del tasso di sollevamento. keywords: central apennines, uplift, neotectonics parole chiave: appennino centrale, sollevamento, neotettonica il quaternario italian journal of quaternary sciences 1166(1bis), 2003, 77-87 78 e. centamore et al. 11.. iinnttrroodduuccttiioonn the topographic growth of the italian apennines was slow during the phase of major plate convergence and crustal shortening which occurred throughout the miocene and pliocene, but increased significantly in the pleistocene (ciaranfi et al., 1983; dramis, 1992; tortorici et al., 1995; argnani et al., 1997; bertotti et al., 1997; carminati et al., 1999; calamita et al., 1999; coltorti & pieruccini, 2000). this uplift is testified by geomorphic and geologic evidences throughout the chain. in the central apennines the oldest landforms, that are gentle rolling or flat summit surfaces, seem to be connected eastward, in the periadriatic basin, to the base of pliocene marine deposits (centamore & nisio, 2003). on the western flank and in the chain, the extensional tectonics related to the opening of the tyrrhenian sea generated several neoautoctonous basins that are older in tuscany (since the tortonian, bossio et al., 1993) and younger in latium and abruzzo (since the pliocene, ambrosetti et al., 1978). this paper examines most of the available literature data about the continental and marine successions cropping out on both sides of the central apennines and within the intermontane basins. we focus on the sedimentary features and stratigraphic elements that could provide time constraints on the recent evolution of the study area, in the context of an uplifting mountain chain affected by extensional tectonics. reviewing the available paleontologic and radiometric data, we point out the main stratigraphic elements that allow the correlation between the sedimentary successions cropping out in the margins of the chain and in the intermontane basins. the results are consistent with a mostly continuous and slow uplift, characterized by a strong increase of the uplift rate by the end of lower pleistocene. 22.. ggeeoollooggiiccaall sseettttiinngg the italian apennines are a fold and thrust chain that, since around 15 myr, has been affected by extensional tectonics as a consequence of the backarc opening of the tyrrhenian basin; the formation of this basin induced the eastward-southeastward migration of the apennines and the foredeep (malinverno & ryan, 1986; patacca & scandone, 1989; patacca et al., 1990; mantovani et al., 1996; faccenna et al., 2001). clastic deposits shed from mesozoic and early cenozoic sediments have been deposited in foredeep and thrust-top basins during the late miocene-early pliocene, in connection with local emergence and erosion of the continental land (centamore & micarelli, 1991; calamita et al., 1999; cavinato & de celles, 1999; cipollari et al., 1999 a, b). since late pliocene through late early pleistocene, a decrease in the rate of the eastward migration of the apennine chain (mantovani et al., 1996) and minor changes in the backarc extension axis were temporally coincident with an increase of the regional emergence of the chain (hippolyte et al., 1994). several authors, citing different proxies among which the occurrence of low-relief summit surfaces in several high-standing parts of the apennines, have appealed to a significant increase in the emergence of all the apennines by the middle pleistocene (ambrosetti et al., 1982; ciaranfi et al., 1983; brancaccio et al., 1984; colella et al., 1987; dramis, 1992; tortorici et al., 1995; amato & cinque, 1999; ascione & cinque, 1999; calamita et al., 1999; coltorti & pieruccini, 2000; d’agostino et al., 2001). the study area, located in the central apennines (fig. 1), is underlain by mesozoic to early cenozoic platform carbonate, marls and terrigenous deposits that are deformed by e-ne-verging thrusts (parotto & praturlon, 1975; patacca et al., 1990; bigi et al., 1991). as for the rest of the chain, the extensional tectonics, related to the opening of the tyrrhenian basin, progressively affected the study area, generating several neoautoctonous basins on the western margin (bossio et al., 1993; ambrosetti et al., 1978) and intermontane depressions in the axial part of the range (dramis, 1992). in the periadriatic sector, divided into minor basins by transversal tectonic structures, the uplift induced a progressive tilting of the marine sediments that generated clinoforms dipping to e-ne (centamore et al., 1990, 1991; bigi et al., 1997). present seismicity indicates that the modern chain continues to be affected by tectonic shortening on the adriatic flank and extension on the tyrrhenian flank, although most of the extensional activity is concentrated along the more elevated axial sectors of the chain (royden et al., 1987; console et al., 1988; gasparini et al., 1988; patacca & scandone, 1989; patacca et al., 1990; lavecchia et al., 1994; amato et al., 1997; montone & mariucci, 1999; negredo et al., 1999; frepoli & amato, 2000). 33.. mmaarriinnee aanndd ccoonnttiinneennttaall ssttrraattiiggrraapphhyy ooff tthhee ssttuuddyy aarreeaa all the sites mentioned in the following paragraphs are reported in fig. 1. 33..11 llaattee mmiioocceennee - lloowweerr pplliioocceennee on the western flank of the apennines, since the tortonian to the early messinian, the extensional tectonics related to the opening of the tyrrhenian sea generated several basins: here the stratigraphic sequences are characterized by the occurrence of fluvial and lacustrine deposits, gradually evolving to littoral sand and clay (fazzini et al., 1972; bossio et al., 1993; carboni et al., 1994; testa, 1995). subsequently, the sedimentation became evaporitic as a response to the messinian salinity crisis (parotto & praturlon, 1975; patacca et al., 1990; roveri et al., 2001). after the messinian regression, marked by an erosion surface, in the lower pliocene, conglomerate, sandy and clayey sediments were deposited in a progressively deeper sea (brandi et al., 1970; ambrosetti et al., 1978; buonasorte et al., 1991; barberi et al., 1994; carboni et al., 1994). the change of depositional environment depended on the marine ingression as well as on the structural pattern of depressed basins with elevated and partially emerged ranges (ambrosetti et al., 1978). in the more western basins the deposition began during the globorotalia margaritae biozone, whereas more to the east (tiber basin) the so-called “argille di fabro” deposits may be referred to the globorotalia puncticulata biozone (ambrosetti et al., 1987; buonasorte et al., 1991; carboni et al., 1994). in the same time interval, the foredeep migrated eastward: valle latina, val roveto, lago del saltotagliacozzo depression, laga and cellino basins (cipollari & cosentino, 1995; centamore et al., 1990; centamore et al., 1991; bellotti, 1991; bigi et al., 1997). the turbidites lying down in the foredeep are unconformably overlain by littoral sand and fluvial-delta polygenic conglomerate (valle del liri, le vicenne, piagge, rigopiano, m. coppe), deposited between late messinian and lower pliocene (centamore et al., 1991; cipollari & cosentino, 1995; bigi et al., 1997; cipollari et al., 1999a, b). 33..22 mmiiddddllee –– eeaarrllyy uuppppeerr pplliioocceennee on the western flank of the apennines, in northern latium, at the disappearing of globorotalia puncticulata and at the first occurrence of globorotalia crassaformis, the sediments changed from bathial clay (“argille di fabro”) to littoral sand (“sabbie a flabellipecten”, “calcare di tarquinia”) and shoreline conglomerate (“conglomerato di città della pieve”) (brandi et al., 1970; ambrosetti et al., 1987; barberi et al., 1994; carboni et al., 1994). these sediments are finer westward, becoming coarser and coarser towards the present chain (buonasorte et al., 1991). the general pattern of the adriatic margin was controlled by structural elements oriented nw-se and ne-sw that defined several basins (teramo, chieti, and vasto basins) alternated with more elevated longitudinal ridges (bigi et al., 1997). in these sectors, notwithstanding marked differences in sedimentation and tectonic evolution, the deposition continued in a marine environ79elements to correlate marine and continental ... ment, producing a thick stratified succession with several minor sequences separated by angular unconformities (bigi et al., 1997). these sediments, which unconformably overlay the “laga flysch”, “cellino flysch”, and the “marne del vomano” formations (cantalamessa et al., 1986; bigazzi et al., 2000; bigi et al., 2000), vary from conglomerate to sand and clay; their base could be referred to the globorotalia crassaformis zone (centamore & nisio, 2003). 33..33 uuppppeerr pplliioocceennee –– lloowweerr pplleeiissttoocceennee in the upper pliocene, on the western margin of the chain, sedimentation persisted with the deposition of marine clay and sandy clay in the civitavecchiamontalto di castro area, in the tiber basin, and more to south, in the ardea basin and pontina plain, even if the successions have been largely truncated by subsequent erosion (carboni, 1975; carboni et al., 1993, carboni et al., 1994; faccenna et al., 1994). at valle ricca a volcanic layer, dated 2.1 myr, has been reported from the upper part of these deposits (carboni et al., 1993). more in general, the upper pliocene succession is cut by an erosion surface on which marine and brackish sandy clay lay down (malatesta & zarlenga, 1985; ambrosetti et al., 1987; buonasorte et al., 1991; carboni et al., 1994). these sediments (“argille sabbiose del chianitevere” in the tiber basin sequence), referred to the lower pleistocene because of the microfacies typical of the globorotalia inflata pp. and of the globigerina cariacoensis zones (ambrosetti et al., 1987; carboni & di bella, 1996), are connected to ancient shorelines, presently uplifted at elevations ranging from 145 to 480 m a.s.l. (girotti & piccardi, 1994). in sectors closer to the mountain chain, upper pliocene continental clay with fig. 1 location of the study area. the main tectonic structures and the localities mentioned in the text are reported. lleeggeenndd main thrust main normal faults sa-ta: salto tagliacozzo depression 1: le vicenne 2: piagge 3: rigopiano 4: monte coppe 5: valle ricca 6: fossa 7: scoppito 8: bellante 9: giovenco valley 10: cupaello 11: polino 12: san venanzo 13: colle fabbri 14: como valley 15: fiorata 16: catignano 17: colle picconetto 80 peaty lens (“argille grigie inferiori”) crops out (ambrosetti et al., 1987). they are unconformably overlain by fluvial-lacustrine sandy clay (“complesso argilloso-sabbioso”) dated lower pleistocene according to the fossil content (ambrosetti et al., 1987; 1995). in the tyrrhenian piedmont belt, santernian infra-littoral sandy clay crop out (di bella, 1994), whereas more to the west, in the coastal sectors, circalittoral pelitic sediments with rare sand layers are dated as emilian (carboni, 1993). extensional tectonics affected the chain producing intermontane basins (demangeot, 1972; calamita et al., 1982; dramis, 1992). these basins are partially filled with sedimentary sequences consisting, from the bottom to the top, of coarse breccia and blocks, lacustrine clayey layers and alluvial conglomerate, gravels and sand, which locally are interfingered each other (bertini & bosi, 1993; cavinato, 1993; galadini, 1999; aa.vv., 2002). in particular, the coarse breccia and the huge blocks locally crop out several kilometers far from any slopes. in the fucino and l’aquila-fossa basins, as well as in the salto and sangro valleys, lacustrine deposits containing huge blocks (“megabreccia”) have been roughly referred to pliocene (demangeot, 1972; bosi & messina, 1991; bertini & bosi, 1993; galadini & messina, 1994; galadini, 1999). in particular, in the fucino basin, siltstone and claystone interbedded with “megabreccia” and characterized by no diagnostic fauna assemblages (ostracods and mollusks), constitute the “lower units” (zarlenga, 1987; cavinato et al., 2002), that correspond to the lower part of the “aielli-pescina supersyntheme” in aa.vv. (2002). the finding of equus stenonis (late villafranchian) in the basal part lacustrine sedimentary sequence of rieti (“upper depositional unit”; cavinato et al., 1987), and of elephas meridionalis vestinus (late villafranchian) in similar deposits within the l’aquila-scoppito basin (esu et al., 1991) refer those sediments to the lower pleistocene, without excluding an older age for the underlying alluvial gravel and sand. on the adriatic margin, the marine sedimentary environment persisted with the deposition, from the bottom to the top, of neritic-littoral sand and of thick pelitic clay with lenses and layers of conglomerate (cantalamessa et al., 1986; centamore & micarelli, 1991; bigi et al., 1997). this sequence and the minor cycles within it are bounded by angular unconformities in the innermost and marginal sectors of the basin, while in the deeper sectors the corresponding deposits are characterized by higher thickness and depositional continuity (cantalamessa et al., 1986; bigi et al., 1997; bigazzi et al., 2000; centamore & nisio, 2003). at bellante, in the upper part of the sequence, a tephra layer, dated 2.13±0.10 myr (bigazzi et al., 2000), has been found just below a minor erosion surface (nisio, 1997) over which neritic conglomerate and sand unconformably lay (centamore & micarelli, 1991; cantalamessa et al., 2002). these latter sediments are truncated by another erosion surface which records a hiatus corresponding to the upper portion of the globorotalia inflata zone (late upper pliocene); they are unconformably overlain by sicilian sandy and gravelly sediments, deposited in a submerged and then emerged beach environment, thus recording the progressive eastward shift of the coastline (cantalamessa et al., 1986; bigi et al., 1997; bigazzi et al., 2000). 33..44 mmiiddddllee pplleeiissttoocceennee around 0.8 myr, on the tyrrhenian flank of the apennines the depositional environment changed laterally from marine littoral in the more depressed areas (e.g. piana pontina) (casto & zarlenga, 1997, barbieri et al., 1999) to continental/marine transitional (at ponte galeria, west of rome) and continental in the area of rome (marra & rosa, 1995). in the intermontane basins, the lower pleistocene lacustrine clay are generally unconformably overlain by coarser sediments which record the transition to alluvial environment. these sediments are frequently entrenched within the lacustrine deposits. the finding of equus altidens (lower-middle galerian) in a buried soil at the base of coarse alluvial sediments in the giovenco valley allows to refer them to the middle pleistocene (blumetti et al., 1997). in the l’aquila-fossa basin, lacustrine sand and clay are dated as middle pleistocene by the occurrence of elephas (p.) antiquus (galerian) (esu et al., 1991; bertini & bosi, 1993). magma upwelling along pre-existing nw-se trending fracture allowed the development of the intraapenninic volcanic vents of cupaello, polino, san venanzo, and colle fabbri (barberi & innocenti, 1980; michetti & serva, 1990; cavinato et al., 1994). in particular, in the rieti basin, the lava of cupaello (dated around 0.4 myr) flowed over a fault slope, related to the extensional tectonics that generated the present geometry of the basin itself (barberi & innocenti, 1980). at least two orders of middle pleistocene fluvial terraces are present along the main valleys (bigi et al., 1995; aa.vv., 2002). in the corno valley the oldest fluvial terraces, located at an elevation of 940 m a.s.l. and around 300 m above the present valley bottom, contain an ash layer dated 0.520±0.005 myr (aa.vv., 2002). moreover, these terrace deposits are locally interfingered with alluvial fan sediments, in which remnants of megaloceroides verticornis, megaloceros cf. m. savini, stephanorinus sp, elephantidae gen., elephas antiquus have been found; this fossil assemblage is typical of the lower part of middle pleistocene (aa.vv., 2002). reworked volcanic layers, dated 0.562±0.004 myr, have been found in sand and carbonate silt (upper part of the “aielli-pescina supersyntheme”) around fiorata, in the sulmona basin (aa.vv., 2002). in the fucino area the older deposits of the “upper units” (cavinato et al., 2002), corresponding to the upper part of the “aielli-pescina supersyntheme” and to the “catignano syntheme” (aa.vv., 2002), are fluvial and deltaic sand and conglomerate, interfingered with lacustrine clay and unconformably overlying the “lower units” (cavinato et al., 2002). a volcanic level found in a core drilled in the lacustrine sediments has been dated 0.541±0.009 myr by 39ar/40ar method (narcisi, 1995). on the adriatic margin of the central apennines, over an erosion surface that presently reaches a maximum elevation of 470 m a. s. l., alluvial deposits lay down (cantalamessa et al., 1986; bigi et al., 1995). at colle picconetto, near catignano, a buried soil overlain by an ash layer dated 0.48±0.04 myr, has been referred to middle pleistocene because of the small mammal faunas and continental molluscs assemblage (marcolini et al., 2000). a similar faunal assemblage has been found in the valdarno basin, within alluvial gravel and sand overlain by a volcanic layer dated around 0.5 e. centamore et al. 81 myr (bigazzi et al., 2000). in middle pleistocene two cold and arid periods induced the formation of stratified slope deposits (coltorti & dramis, 1988). north of the study area, in the norcia and cascia basins, at the top of the oldest sediments some soils developed; they have been dated 0.25-0.29 myr by k/ar method (coltorti et al., 1987). the stratified slope deposits are often interfingered with fluvial sediments of the terraces. 33..55 uuppppeerr pplleeiissttoocceennee--hhoolloocceennee along the tyrrhenian coastal belt, several orders of marine terraces developed in the upper pleistoceneholocene. terraced marine sediments containing strombus bubonius (tyrrhenian stage) are presently located at elevation ranging from 27 m (tarquinia) to 20 m (palidoro) and 6-12 m (southern latium) (blanc, 1935, 1936; hearty & dai pra, 1986; radtke, 1986; dai pra, 1995 and references within; palieri & sposato, 1988). pebbly and gravely continental deposits, cropping out close to pomezia, have been referred to tyrrhenian by malatesta & zarlenga (1985). in the pontina plain, coastal, lagoon, and eolian sediments have been dated as upper pleistocene and holocene (barbieri et al., 1999; sevink et al., 1984). more to the north, a 50 m thick clayey and sandy sequence, deposited in a coastal-lagoon-brackish environment, has been drilled close to tiber river mouth (carboni, 1993). in the apenninic range, the lacustrine environment, characterized by the deposition of clayey, sandy clayey and peaty sediments, persisted, where the intermontane basins like fucino continued to be internally drained (d’agostino et al., 2001). moraine, loess, slope deposits, alluvial fan, and fluvio-lacustrine sediments, precisely dated by the occurrence of tephra layers, record the strong climatic changes of the upper pleistocene-holocene (frezzotti & giraudi, 1992; giraudi, 1998 a, b, 2001). the interaction of these climatic variations with the deep stream incision caused by the regional uplift continued to form alluvial terraces (coltorti & dramis, 1988; dramis, 1992). in the velino valley, the third order of alluvial terraces contains travertine dated 0.080-0.18 myr by u/th method (carrara et al., 1992). on the adriatic side of the range, continental deposits (alluvial fan and alluvial plain gravels) containing silty-travertine layers have been referred to the upper pleistocene-holocene (cantalamessa et al., 1986, bigi et al., 1997; cantalamessa et al., 2002). in particular, three orders of fluvial terraces formed in the valleys; the younger order developed in the holocene (calderoni et al., 1996). 44.. ddiissccuussssiioonn the results from reviewing the available literature on the continental and marine successions cropping out on both sides of central apennines and in the intermontane basins highlight some stratigraphic elements that provide time constraints for the recent evolution of the study area, in the context of an uplifting mountain chain affected by extensional tectonics. after the messinian regression, in the late miocene-lower pliocene a marine transgression occurred in the backarc basins on the western flank of the chain, whereas to the east littoral sand and fluvial and delta conglomerate unconformably overlay turbidite deposits in the foredeep and thrust-top basins. the conglomerate were mostly supplied with locally outcropping carbonatic and flysch rocks, even if clasts were originated from very distant sources (accordi & carbone, 1988; cipollari et al., 1999 b). the well expressed erosion surface overlain by coarse conglomerate deposited in a continental environment suggests that the forming apennines were partially emerged and eroded by surface processes. in middle pliocene, on the western flank of the range, the depositional environment changed from bathial to littoral and shoreline (brandi et al., 1970; ambrosetti et al., 1987; barberi et al., 1994) indicating elements to correlate marine and continental ... fig. 2 sketch of the tiber basin in the southern umbria stratigraphy (from ambrosetti et al., 1987, modified) as an example of basin evolution on the tyrrhenian flank of the apennines. marine succession: af) “argille di fabro”; sf) “sabbie a flabellipecten”; ccp) “conglomerato di città della pieve”; asct) “argille sabbiose del chiani-tevere”. continental succession: agi) “argille grigie inferiori”; cas) “complesso argilloso-sabbioso”; tl) peat and slime; ta) travertine; cds) thick debris deposits. 82 marine regression. a depositional hiatus after 2.1 myr followed (fig. 2), corresponding to at least a portion of the globorotalia inflata zone (upper pliocene). this relatively strong sea level lowering occurred regionally, as suggested by the erosion surface above a 2.1 myr old volcanic layer at bellante, in the periadriatic basin (fig. 4). the presence of angular unconformities within the sedimentary sequence testifies the progressive tilting of the periadriatic basin as a consequence of the interaction of the slow emersion of the chain and the sea level changes. the middle-upper pliocene marine deposits are coarser close to the flanks of the present chain indicating that the axial part of the apennine had already emerged (fig. 3). here, geomorphic processes shaped a low relief landscape whose fragmented relics are presently visible in the summit portion of the chain. in the emerged apenninic range, between the upper pliocene and lower pleistocene, extensional tectonics gave rise to nw-se trending normal faults that, displacing the previous low relief landscape, generated several intermontane depressions (fig.3). the first deposits associated to the formation of these basins are coarse breccia and blocks, that are interfingered and overlaid by lacustrine sediments. the coarse breccia have been probably generated on bare slopes in colddry conditions during the upper pliocene (shackleton et al., 1984; horowits, 1989). gravitational processes, probably triggered by high magnitude earthquakes, mobilized this weathering material together with the huge blocks and transported them up to some kilometers far from the feeding areas (demangeot, 1965; aa.vv., 2002). unfortunately, there are no precise chronological data for this event, but since the breccias are overlain e. centamore et al. fig. 3 – sketch of the lowe pliocene-lower pleistocene evolution of the eastern apennine flank and of the adjacent periadriatic basin (from centamore & nisio, 2003, modified). whereas the apennines were uplifting, being affected by extensional tectonics and shaped by surface processes, in the periadriatic basin several cycles of marine deposits lay down and successively were tilted and emerged as e result of the uplift and of the progressive eastward shifting of the coastline. aappeennnniinnee tthhrruusstt bbeelltt ssuummmmiitt ssuurrffaaccee ((ssoo)) iinnttrraammoonnttaarree ddeepprreessssiioonnss aaddrriiaattiicc ffoorreellaanndd ppeerriiaaddiiaattrriicc bbaassiinn ppeerriiaaddiiaattrriicc mmoonnoocclliinnee lloowweerr pplliioocceennee ssttaaggee mmiiddddllee pplliioocceennee ssttaaggee mmiiddddllee--uuppppeerr pplliioocceennee ssttaaggee llaattee pplliioocceennee--lloowweerr pplleeiissttoocceennee ssttaaggeess by lower pleistocene deposits, we could hypothesize that they could be referred to the same cold and dry climatic phase that induced marine regression after 2.1 myr, in correspondence with the globorotalia inflata biozone. during lower pleistocene, as a consequence of more humid and warm climatic conditions (shackleton et al., 1984; horowits, 1989) in the intermontane basins, the sedimentation became coarser, but the persistence of lacustrine or low gradient fluvial environment suggests that the basins were internally drained (d’agostino et al., 2001). in the santernian, marine transgression occured in both the adriatic and tyrrhenian margins (figg. 2, 4). around 0.8 myr b.p., on both flanks of the range, the marine regression relative to the isotopic stage 22 induced backward coastline shifting and the deposition of transitional marine/continental and continental deposits. contemporaneously a marked increase in the uplift rate of the apenninic range occurred; this strong uplift, reported all along the italian peninsula (ambrosetti et al., 1982; ciaranfi et al., 1983; dramis, 1992; moretti, 1993; tortorici et al., 1995; calamita et al., 1999; coltorti & pieruccini, 2000; d’agostino et al., 2001), induced widespread deep fluvial erosion (fig. 3). therefore, most intermontane depressions were reached by the headward river erosion which breached the basin thresholds, draining off the lakes and cutting the filling sediments. the interaction between the uplift and the strong climatic changes of the middle-upper pleistocene generated several orders of fluvial and marine terraces along the tyrrhenian coast. the formation of the fluvial and marine terraces was alternate because during cold periods, the sea level drop induced rivers to incise downstream, whereas large amounts of sediments from poorly vegetated valley slopes were washed in the rivers upstream. conversely, during warm periods, the sea level rise induced aggradation towards the mouth and incision upstream. on the adriatic flank, the lower pleistocene coastal deposits, uplifted and tilted to the ne, were isolated on the interfluves by the strong stream incision, whereas five orders of fluvial terraces formed along the valleys until the holocene. on the basis of the reviewed data and of their discussion we could point out that the topographic growth of the apennines began at least in the miocene when the extension was affecting only the western portions of the deforming thrustbelt. no data suggest that strong changes of the uplift rate occurred until the end of lower pleistocene, when a long-wave uplift affected the apennines and the tyrrhenian and adriatic coastal belts. this is confirmed by the present maximum elevation (470-480 m) of the lower pleistocene shorelines and relative deposits on both flanks of the chain (girotti & piccardi, 1994; bigi et al., 1995). on the latium coastal belt, the maximum elevation of the tyrrhenian marine ter83elements to correlate marine and continental ... fig. 4 sketch of the pliocene-middle pleistocene evolution of an intermontane depression (from centamore & nisio, 2003, modified). a) in the pliocene, the forming apennines were partially emerged and surface processes shaped a low relief landscape presently located on the summit portion of the chain. b) in the upper pliocene-lower pleistocene the intermontame depressions were filled mostly by coarse breccia and lacustrine deposits. c) at the end of the lower pleistocene the lacustrine and/or low gradient fluvial deposits suggest that the basins were internally drained. d) in the middle pleistocene, a marked increase in the uplift rate induced the headward stream erosion to enter in the intermontane basins and to incise their deposits. old landscape minor erosional surfaces fault scarp fault scarp fault scarp lacustrine deposits fluvio-lacustrine deposits fluvio-lacustrine deposits coarse breccia coarse breccia coarse breccia fluvial terraces a) b) c) d) race is around 27 m (palieri & sposato, 1988). according to these data and their discussion, we could roughly calculate an uplift rate of around 0.5 mm/yr in the last ~1 myr. 55.. ccoonncclluussiioonn in this paper we examine most of the available literature data on the continental and marine successions cropping out on both sides of the central apennines and within the intermontane basins. we focus on the sedimentary features and stratigraphic elements that could provide time constraints on the recent evolution of the study area in the context of an uplifting mountain chain affected by extensional tectonics. the obtained results are consistent with a mostly continuous and slow uplift, started in the upper miocene-lower pliocene and followed by a phase of higher uplift rate by the end of lower pleistocene. this uplift increase induced an equally strong change in the landscape of the apennines, as suggested by the geomorphological and stratigraphical evidences of the intermontane basins, not only in the latium-abruzzo area, but also all along the central apennines (for example norcia, colfiorito, terni basins). they indicate that the general drainage system changed from internally drained fluvial-lacustrine basins to open river systems, delivering their sediments from the intermontane basins to the adriatic and tyrrhenian seas. rreeffeerreenncceess aa.vv., 2002 stratigrafia dei depositi continentali, carg abruzzo, submitted. accordi g. & carbone f. 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ssuullllaa ccoolllliinnaa ddii ttoorriinnoo pprreessssoo vviillllaa gguuaalliinnoo ((nnww iittaallyy)) mmaarriiaa ggaabbrriieellllaa ffoorrnnoo11,, ggiiuusseeppppee bbeenn22,, ppaaoollaa bbooaannoo11,, ppiieerrccaarrlloo bbooccccaa33,, vvaalltteerr bbooeerroo44 && rroobbeerrttoo ccoommppaaggnnoonnii55 1dipartimento di scienze della terra, università di torino 2servizi tecnici di prevenzione, regione piemonte 3libero professionista, c. regina margherita 1, torino 4dipartimento di valorizzazione e protezione delle risorse agroforestali, università di torino 5dipartimento di scienze mineralogiche e petrografiche, università di torino. riassunto il quaternario, italian journal of quaternary sciences gli studi più recenti riguardanti il versante occidentale della collina di torino evidenziano una successione di superfici pianeggianti terrazzate da riferire al modellamento fluviale del rilievo, realizzatosi in una situazione morfologica sensibilmente diversa dall’attuale. l’estrema antropizzazione dell’area collinare e la diffusione della copertura eolica ostacolano lo studio di queste superfici e in particolare rendono difficile valutare se, nei diversi casi, esse conservino o meno gli originari depositi alluvionali: la realizzazione di sondaggi in corrispondenza al lembo di superficie di villa gualino, sospeso di circa 130 m rispetto alla pianura, consente invece, in questo caso, di riconoscere nelle stratigrafie la successione fluviale, con spessore di circa 5m, interposta tra il substrato e il loess. in particolare la caratterizzazione geotecnica e lo studio dei campioni raccolti dal punto di vista tessiturale, mineralogico e pedologico, evidenziano come questi sedimenti si differenzino sia dai termini marini sottostanti, sia dalla soprastante copertura eolica. l’insieme delle osservazioni effettuate, pur limitate ad un singolo lembo di superficie terrazzata e quindi necessariamente da integrare con le osservazioni al contorno, indica per i depositi fluviali in esame una provenienza dall’antistante area alpina, con un particolare contributo dal bacino idrografico del f. dora riparia, in un intervallo di tempo precedente rispetto all’impostazione del f. po. le osservazioni pedologiche, in assenza di altri dati stratigrafici, indicano una attribuzione cronologica della successione fluviale alla parte superiore del pleistocene medio, in accordo con il riferimento al tardo pleistocene superiore già noto per il loess eolico. abstract remnants of fluvial deposits from northwestern alpine basins in the turin hills at villa gualino (nw italy). recent investigation on the western slope of the turin hills reveals a series of flat terraced surfaces produced by fluvial modelling occurred when morphological conditions were very different from the present. intense human occupation of the hillsides and diffusion of aeolian loess hinder the study of these surfaces and make it hard to determine whether they still retain the original alluvial deposits or not. stratigraphic examination of some boreholes made during rectructuring of villa gualino on a terraced surface (130 m above the po plain level) points out the presence of fluvial deposits in the immediate subsoil between the marine substratum and the aeolian cover. evidence in favour of this view is provided first of all by penetrometric tests of a cover 10-15 m thick of incoherent sediments, unusual for these hills. the stratigraphic data show the presence of an approximatively 5-m thick lenticular sandy to silty fluvial body that is distinct from the substratum and separated from it by an evident erosion surface. the concave shape of the base indicates the presence of a channel. the subhorizontal upper surface, on the other hand, points to the development of a strip of alluvial plain subjected to overspill flooding. moreover in the alluvial deposits fossils, which are abundant in the marine substratum, and bedding are lacking. textural and mineralogical data show that the grain size of fluvial deposits is much finer than substratum and less selected than loess, and that their mineral composition qualitatively and quantitatively is different. pedological data reveal a marked weathering different from that of both the substratum and the overlying loess. these observations point to a surface erosion earlier than the formation of the alluvial body and that significant time gap occurred before the loess deposition. in the absence of other stratighraphic data, the fluvial deposits can be assigned to the upper part of middle pleistocene in agreement with the accepted, late upper-pleistocene age of the aeolian loess. these observations are confined to a single strip of terraced surface and must be supplemented with further evidence from its surroundings. these preliminary results suggest that the fluvial deposits are derived from the facing mountain alpine area, especially from the hydrographic basin of the dora riparia river, prior the establishment of the po river. parole chiave: depositi fluviali, collina di torino, pleistocene medio. keywords: fluvial deposits, turin hills, middle pleistocene il quaternario italian journal of quaternary sciences 1155(2), 2002, 175-185 11.. iinnttrroodduuzziioonnee ee llaavvoorrii pprreecceeddeennttii villa gualino, ubicata sul versante occidentale della collina di torino alla quota di 352 m e compresa nel territorio comunale di torino (fig. 1), sorge su un lembo di superficie subpianeggiante sospesa di circa 130 metri rispetto all’incisione del po. la redazione del progetto di ristrutturazione degli edifici esistenti e di edificazione di nuovi fabbricati ha offerto l’opportunità di condurre una campagna geognostica finalizzata alla valutazione della stratigrafia dell’immediato sottosuolo e alla sua caratterizzazione geotecnica. nel corso della esecuzione di una prima serie di sondaggi e di prove penetrometriche continue, statiche e dinamiche, è emersa una situazione geologica locale del tutto particolare, non inquadrabile nel contesto stratigrafico tipico della collina di torino, contraddistinto in genere dal diffuso affioramento o subaffioramento della 176 m.g. forno et alii successione marina terziaria con una sottile coltre di loess eolico. tale situazione peculiare è riassumibile nello sviluppo di una copertura relativamente potente con caratteristiche geotecniche scadenti (figg. 2 e 3): lo spessore anomalo dei sedimenti incoerenti, variabile tra 10 e 15 m, poteva essere congruente con il modello interpretativo messo a punto attraverso i più recenti sviluppi delle ricerche geologiche sull’area collinare (boano & forno, 1997). scopo del presente lavoro (coordinato da m. g. forno) è quello di descrivere ed interpretare la successione di depositi che costituiscono in superficie il lembo di villa gualino e in particolare di verificare se alcuni termini di questa corrispondano a depositi fluviali analoghi a quelli segnalati localmente in corrispondenza ad altri lembi terrazzati conservati nel versante occidentale della collina di torino. con questa finalità, in seguito alle indagini geotecniche che hanno fornito lo spunto per questa ricerca (p. bocca), sono stati eseguiti il rilevamento geologico di dettaglio e la descrizione delle carote dei sondaggi (p. boano e m. g. forno) ed effettuate una serie di analisi tessiturali (g. ben), mineralogiche (p. boano e r. compagnoni) e pedologiche (v. boero). le interpretazioni sono frutto della discussione collegiale degli autori. la letteratura geologica sulla collina di torino riguarda quasi esclusivamente la successione marina terziaria del substrato: per l’area su cui sorge villa gualino il foglio 56 “torino” della carta geologica d’italia iia ed. (bortolami et al., 1969) e le relative note illustrative (bonsignore et al., 1969) riportano, al di sopra dei sedimenti marini del complesso di baldissero, una coltre discontinua di loess; la distribuzione di quest’ultimo e dei prodotti colluviali legati alla sua rielaborazione è stato oggetto di studi specifici (forno, 1979; 1990). e’ noto da tempo che l’impostazione del f. po a nord della collina di torino è di età molto recente (carraro, 1976); i precedenti andamenti del collettore del bacino piemontese meridionale (aa in fig. 1) sono conservati sul versante meridionale del rilievo collinare (carraro et al., 1982): le tracce di questo corso d’acqua corrispondono a relitti di meandri con raggio di curvatura chilometrico che conservano diffusamente gli originari sedimenti alluvionali prevalentemente siltosi e localmente ghiaiosi (forno, 1979; compagnoni & forno, 1992). solo recentemente (boano & forno, 1997) è stata segnalata la presenza di relitti di forme fluviali anche sul versante opposto, occidentale: queste sono rappresentate da una successione di superfici terrazzate relitte, sulle quali è conservata localmente una esigua copertura di depositi alluvionali. tali superfici sono distribuite in corrispondenza delle dorsali spartiacque del reticolato idrografico locale e appaiono allungate in direzione n-s, trasversalmente rispetto all’andamento di questo reticolato: i caratteri morfologici di questi lembi terrazzati suggeriscono il legame genetico con un importante corso d’acqua che convogliava il drenaggio del bacino piemontese settentrionale (bb in fig. 1) prima dell’impostazione del f. po al margine settentrionale della collina di torino (boano & forno, 1997). la presenza delle tracce di antichi corsi d’acqua distribuite in una ampia fascia altimetrica sul versante esterno della collina di torino indica che quest’area, nell’intervallo di tempo precedente alla diversione del po, è stata interessata da un sensibile sollevamento recente a cui è connesso l’approfondimento del drenaggio (boano et al., 2000): il reticolato idrografico attuale ha successivamente dissecato queste forme, che risultano pertanto conservate in lembi di piccole dimensioni. 22.. iinnqquuaaddrraammeennttoo mmoorrffoollooggiiccoo ee ggeeoollooggiiccoo ddeellll’’aarreeaa il tratto del versante occidentale del rilievo collinare su cui insiste il complesso degli edifici di villa gualino, caratterizzato da un’acclività media sensibile (12 %), é interrotto, nella fascia altimetrica compresa tra 345 e 350 m, da un lembo di superficie con acclività fig. 1 ubicazione dell’area di studio nell’ambito del versante occidentale della collina di torino. location of the studied area on the western slope of the turin hills. sensibilmente inferiore (2 %), allungato per circa 300 m in direzione n-s. le osservazioni morfologiche consentono di ipotizzare che questo lembo pianeggiante, con estensione complessiva di circa 15.000 m2, sia parte di origine naturale e parte sia stato invece realizzato artificialmente, con un ampliamento della superficie originaria. in particolare il settore a quota inferiore, sviluppato tra 345 e 347 m, su cui sorgono gli edifici della fondazione gnocchi e del centro convegni di villa gualino (settore aa in figg. 2 e 4) risulta correlabile altimetricamente con altri lembi pianeggianti, interpretabili come relitti di un’unica superficie che mostra nel suo insieme una modestissima inclinazione verso nord, successivamente terrazzata (boano & forno, 1997). il settore a quota superiore, sviluppato tra 347 e 350 m, su cui sorgono la residenza di villa gualino e il piazzale antistante (settore bb in figg. 2 e 4), in più punti mostra di essere modellato in materiale di riporto e non risulta correlabile con altri lembi di superfici pianeggianti: tali elementi inducono a interpretarlo parte come una forma di accumulo artificiale sull’originaria prosecuzione del settore aa e parte come il prodotto dello spianamento artificiale di un tratto del versante soprastante. i dati geologici di superficie consentono una differenziazione anche dal punto di vista stratigrafico dell’area interpretabile come il lembo pianeggiante originario (fig. 4). in particolare nel settore aa si sviluppa una diffusa e potente copertura di loess eolico che impedisce le osservazione geologiche dell’immediato sottosuolo, rendendo la successione fluviale sottostante individuabile esclusivamente tramite i sondaggi (v. §3.): la coltre eolica mostra una tessitura siltosa, molto omogenea arealmente, porosità elevata e assenza di stratificazione; contiene diffusamente gusci di gasteropodi continentali. e’ interessata da un suolo di colore giallo-bruno (10yr 4/6), con spessore di alterazione superiore ai 2 m, in accordo con l’età tardo pleistocenica superiore (forno, 1979); caratteristica di questi sedimenti è inoltre l’evidente fessurazione prismatica. nel settore bb, al di sotto di una copertura di loess e di materiali di riporto, affiorano invece localmente prodotti colluviali: corrispondono a mescolanze sabbioso-siltose scarsamente addensate, con colore variabile tra il bruno (7,5yr 4/4) e il grigio (5y 4/4); la loro natura eterogenea è legata al fatto che rielaborano indifferentemente il substrato e i diversi termini della copertura quaternaria. sui versanti circostanti il lembo di villa gualino si osserva infine il diffuso subaffioramento del substrato marino terziario (complesso di baldissero miocene medio), costituito essenzialmente da alternanze sabbiose e ghiaiose di colore grigio-oliva (5y 4/4): al di sopra si sviluppa una copertura discontinua, con spessore esiguo, essenzialmente di natura eolica. in particolare alcuni affioramenti del substrato mettono in luce sabbie debol177lembi di depositi fluviali ... mente cementate che mostrano un’evidente stratificazione decimetrica ed appaiono inclinate di circa 20° verso 250°: sono interessate da due sistemi di fratture, con immersione rispettivamente di 45° verso 85° e di 55° verso 340°, entrambi sottolineati da riempimenti carbonatici con spessore di circa 0,5 cm; localmente si hanno ridotti affioramenti di ghiaie minute. 33.. llaa ssuucccceessssiioonnee ssttrraattiiggrraaffiiccaa ddeell ssoottttoossuuoolloo ddii vviillllaa gguuaalliinnoo aa)) iinntteerrpprreettaazziioonnee ssttrraattiiggrraaffiiccaa ddeeii ssoonnddaaggggii i sondaggi sono ubicati prevalentemente nel settore aa nel tratto di raccordo tra le aree su cui sorgono gli edifici della fondazione gnocchi e della residenza di villa gualino (sondaggi s1, s2, s3 e s4) e subordinatamente nel settore bb su cui si sviluppa il fig. 2 carta topografica di dettaglio della superficie di villa gualino con l’ubicazione delle prove penetrometriche statiche (triangoli) e dei sondaggi (cerchietti): i sondaggi s1, s2, s3, s4, e3 e f2, utilizzati per la ricostruzione stratigrafica, sono contraddistinti da cerchietti pieni. detailed topographic map of the villa gualino area: triangles and circles indicate the sites of penetrometric tests cpt and boreholes, respectively; the studied boreholes s1, s2, s3, s4, e3 e f2 are marked by full circles. 178 m.g. forno et alii piazzale antistante la residenza di villa gualino (sondaggio f2) e nel versante sottostante (sondaggio e3) (fig. 2). in tutti i sondaggi, nella parte più superficiale, è stata osservata una copertura costituita da terreno di riporto, con spessore variabile tra 2 e 6 m. le osservazioni stratigrafiche delle carote dei sondaggi ubicati nel settore aa (s1, s2, s3 e s4 in figg. 2 e 5) suggeriscono che tra il substrato e il loess eolico si sviluppi una sequenza relativamente potente, i cui caratteri suggeriscono, come si vedrà in seguito, l’origine fluviale. in particolare, nella parte inferiore delle carote, si riconoscono alternanze di sabbie e ghiaie minute, caratterizzate da evidente stratificazione piano-parallela, da colore verde-grigio e dall’abbondanza di microfossili marini, confrontabili con il substrato affiorante (11 in figg. 4b e 4c). al di sopra, separata dal termine sottostante tramite un limite netto, erosionale, si osserva una sequenza costituita da sabbie fini di colore bruno-giallastro (10 yr 5,4/4) e da silt argillosi di colore bruno (7,5 yr 4/4), entrambi privi di evidenti strutture sedimentarie e di resti fossili (rispettivamente 22aa e 22bb in figg. 4b e 4c). questi sedimenti, con spessore variabile tra 2 e 5 m, non risultano confrontabili con nessuno dei termini superficiali: pur nell’impossibilità di effettuare osservazioni di superficie per l’assenza di affioramenti, le caratteristiche sedimentologiche individuabili nelle carote sono compatibili con il riempimento di un canale fluviale, interessato successivamente da fenomeni di esondazione. i principali elementi a favore dell’origine fluviale di questi sedimenti (22 in figg. 4b e 4c) sono rappresentati dalla natura erosionale della superficie di appoggio e dalla giacitura discordante rispetto al substrato marino, come osservabile nelle carote, e dalla geometria complessivamente lenticolare del corpo sedimentario, quale risulta dalla correlazione dei profili. tale geometria è caratterizzata da una base concava modellata nel substrato, legata verosimilmente allo sviluppo del canale, e da un tetto suborizzontale corrispondente all’espressione morfologica dell’originaria pianura alluvionale, successivamente terrazzata dal corso d’acqua e sepolta dal loess eolico. un altro elemento significativo è rappresentato dall’osservazione che questo corpo mostra di chiudersi lateralmente sia in corrispondenza al tratto di versante al di sotto del settore aa, sia in corrispondenza al settore bb. il termine più superficiale è rappresentato infine da silt estremamente selezionati dal punto di vista tessiturale, caratterizzati da colore bruno-giallastro (10 yr 4/6) e dalla diffusione delle concrezioni carbonatiche, privi di stratificazione e ricchi di gasteropodi continentali, assimilabili al loess eolico affiorante (44 in figg. 4b e 4c). le osservazioni delle carote relative ai sondaggi ubicati rispettivamente nel settore bb (f2 in figg. 2 e 5) e lungo il versante sottostante (e3 in figg. 2 e 5) evidenziano una successione diversa da quella precedente. nel primo caso, interposti tra i termini 11 e 44 sono presenti mescolanze sabbioso-siltose, eterogenee dal punto di vista tessiturale e come colorazione: le loro caratteristiche sono confrontabili con quelle dei prodotti colluviali affioranti (33 in figg. 4b e 4c). nel secondo caso si osserva invece la sovrapposizione diretta del loess eolico sul substrato marino (11 e 44 in fig. 5). e’ da sottolineare che in corrispondenza a entrambi questi sondaggi non sono presenti i termini fluviali 22aa e 22bb, che quindi risultano presenti esclusivamente nel settore aa, interpretabile come il lembo pianeggiante originario (cf. §2.). fig. 3 caratteri geotecnici dei sedimenti in corrispondenza al settore bb, come risulta dalle prove penetrometriche. g e o t e c h n i c characteristics of sediments in the sector bb, resulting from the penetrometric tests. resistenza laterale resistenza unitaria di attrito laterale locale fs (mpa) resistenza alla punta resistenza alla punta qc (mpa) p ro fo n d it à (m ) prova per2 prova per2 p ro fo n d it à (m ) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0 5 10 15 20 25 30 35 40 45 50 55 60 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 fig. 4a carta topografica della superficie di villa gualino, con l’indicazione delle tracce dei profili rappresentati in figure 4b e 4b. il settore aa, indicato con il rigato ravvicinato, corrisponde all’areale di distribuzione dei sedimenti fluviali; il settore bb, indicato con il ri-gato distanziato, corrisponde all’areale di distribuzione dei terreni di riporto. fig. 4b e fig. 4c rappresentazione in profilo delle stratigrafie dei sondaggi e profili geologici interpretativi: le profondità indicate si riferiscono al piano campagna. i simboli utilizzati sono i seguenti: 1) alternanze di sedimenti ghiaiosi e sabbiosi marini, ricchi di microfossili (complesso di baldissero miocene medio); 2) successione di depositi fluviali sabbiosi (a) e siltosi (b), caratterizzati da un suolo con spessore di alterazione superiore a 4 m, patine di argilla discontinue e colore bruno (7.5 yr 5/6) (pleistocene medio); 3) depositi colluviali eterogenei, con grado di pedogenesi variabile (pleistocene superiore); 4) loess eolico ricco di gasteropodi continentali, caratterizzato da un suolo con spessore di alterazione di circa 2 m e colore brunogiallastro (10 y r 4/6) (pleistocene superiore); 5) terreno di riporto. detailed topographic map of the villa gualino area with location of sectors aa and bb and cross sections. cross sections with stratigraphic records of boreholes: depth is referred to the surface. 1) alternating sandy and gravelly marine sediments rich in microfossils (complesso di baldissero middle miocene); 2) sandy (a) and silty (b) fluvial sequence capped by a brown soil (7.5 yr 5/6), at least 4m thick, with discontinuous clay patinas (middle pleistocene); 3) heterogenous and variously wheathered colluvial deposits (upper pleistocene); 4) aeolian loess rich in continental molluscs, capped by a yellowish brown soil (10 yr 4/6), at least 2 m thick (upper pleistocene); 5) dump. 179lembi di depositi fluviali ... 180 i dati analitici di carattere geotecnico, tessiturale, mineralogico e pedolologico di seguito riportati confermano le ipotesi circa la presenza di una successione alluvionale in corrispondenza al settore aa e consentono di stabilire quindi che, almeno localmente, ai lembi terrazzati descritti sono associati depositi fluviali. bb)) ppaarraammeettrrii ggeeootteeccnniiccii nell’area di villa gualino la stesura del progetto di ristrutturazione degli edifici esistenti e di edificazione di nuovi fabbricati ha comportato l’esecuzione di una serie di indagini geognostiche (fig. 2), così come previsto dal quadro normativo del dm. ll.pp. 11/3/1988. i parametri geotecnici indice misurati in occasione della realizzazione delle prove penetrometriche hanno evidenziato la presenza di una copertura di sedimenti sciolti, relativamente potente, con caratteristiche geotecniche scadenti (fig. 3). in particolare, sulla base delle correlazioni empiriche tra prove geognostiche e parametrizzazione del terreno più note e di uso generalizzato impiegate nel campo della meccanica dei terreni, sono stati misurati per questi sedimenti i valori di resistenza penetrometrica dinamica scpt n= 3-4, di resistenza penetrometrica statica cpt alla punta rp=35-35 mpa e di attrito laterale fs=0,1 mpa, di resistenza al taglio non drenata cu da vane test = 0,5 kg/cmq e di resistenza unitaria non drenata al poket 2cu= 1,12 kg/cmq. le caratteristiche della copertura hanno portato ad ampliare il quadro conoscitivo mediante un approfondimento di indagine: sono stati quindi eseguiti numerosi sondaggi a carotaggio continuo (s1, s2, s3, s4, f2 ed e3 e altri privi di sigla in fig. 2) e raccolti una ventina di campioni rappresentativi delle diverse profondità di indagine (fig. 5), al fine di caratterizzare i parametri geotecnici. i dati più significativi si riferiscono a prove di taglio diretto con valutazione dell’angolo di resistenza al taglio residua compreso tra 27,5° e 31,4° e a prove di valutazione dei limiti di consistenza con limite liquido ll compreso tra 28,5% e 33,8%, limite plastico lp tra 24,3% 23% e indice di plasticità ip tra 4,2% e 10,8%. l’insieme dei dati geognostici e di laboratorio ha permesso di evidenziare lo spessore significativo dei sedimenti incoerenti, variabile tra 10 e 15 m e quindi anomalo per l’area collinare, in base al quale è stato predisposto il progetto esecutivo dei nuovi edifici. cc)) ccaarraatttteerrii tteessssiittuurraallii sono stati presi in esame dal punto di vista tessiturale due gruppi rispettivamente di 3 e 4 campioni provenienti dai sondaggi f2 ed e3 ad una profondità compresa tra 15 e 12 m, riferibili al substrato, tre gruppi di 3 campioni provenienti rispettivamente dai sondaggi s1, s2 e s3 e un gruppo di 4 campioni provenienti dal sondaggio s4 ad una profondità compresa tra 12 e 8 m, riferibili ai sedimenti fluviali (considerati in modo indifferenziato a causa della scarsità del materiale a disposizione), e infine due gruppi rispettivamente di 7 e 9 campioni provenienti dai sondaggi f2 ed e3 ad una profondità compresa tra 8 e 4 m, riferibili al loess eolico (fig. 5). le analisi granulometriche per la determinazione delle percentuali in peso di ciascuna classe di particelle costituenti i sedimenti in esame sono state effettuate con la procedura per via umida e per la frazione fine, avente diametro inferiore a 0.074 mm , con l’ analisi per sedimentazione mediante densimetro a.s.t.m. 152h, secondo le norme a.s.t.m. e le raccomandazioni a.g.i. sulle prove geotecniche di laboratorio del 1994. l’osservazione dei sedimenti individuati alla base dei sondaggi f2 ed e3 e le relative analisi granulometriche mettono in evidenza la presenza di nette alternanze di ghiaie sabbiose, debolmente limose, e di sabbie limose con ghiaia, riferibili al substrato marino: la curva granulometrica di sintesi conferma la tessitura grossolana di questi sedimenti (11 in fig. 6). l’esame dei termini incontrati nella parte intermedia dei sondaggi s1, s2, s3 e s4, sviluppati al di sopra del substrato marino, e le relative analisi granulometriche evidenziano la presenza di una successione fluviale costituita alla base da limi molto sabbiosi e nella parte alta da limi molto argillosi. la curva granulometrica di sintesi conferma l’esistenza di sedimenti caratterizzati da tessitura nettamente più fine, rispetto al substrato, e da una modesta selezione, come suggerito dallo sviluppo di “code” sia ghiaiose che argillose, in accordo con la genesi fluviale ipotizzata per questi sedimenti (22 in fig. 6). infine l’osservazione dei sedimenti più superficiali incontrati nelle stesse stratigrafie e le relative analisi granulometriche evidenziano lo sviluppo di una copertura costituita da sedimenti siltosi estremamente selezionati, assimilabili al loess eolico: la curva granulometrica di sinm.g. forno et alii f2e3 s1 1 42 s2 s3 320 325 330 335 340 345 350 s4 5 analisi mineralogiche analisi tessiturali analisi geotecniche analisi pedologiche 3 fig. 5 localizzazione dei campioni presi in esame: 1) substrato marino; 2) depositi fluviali; 3) depositi colluviali; 4) loess eolico; 5) terreno di riporto. location of studied samples: 1) marine sediments; 2) fluvial sediments; 3)colluvial sediments; 4) aeolian loess; 5) dump. tesi, realizzata previa eliminazione dei granuli cementati e caratterizzata da un andamento subverticale e dall’esclusiva presenza di limo e sabbia, conferma la presenza di sedimenti con elevata selezione, in accordo con lo sviluppo di una copertura di loess (33 in fig. 6). dd)) ccoommppoossiizziioonnee mmiinneerraallooggiiccaa le analisi sono state effettuate mediante l’osservazione al microscopio binoculare del trattenuto al setaccio 200 mesh, con apertura delle maglie di 0,074 mm: i granuli, corrispondenti alla classe granulometrica della sabbia molto fine secondo la classificazione di wentworth, dopo essere stati trattati in mortaio con acetone per eliminare eventuali patine di incrostanti, sono stati posti su vetrini, fissati seppure blandamente con eugenolo, quindi coperti con vetrino copri oggetto. sono stati osservati complessivamente 26 campioni; i caratteri tessiturali e pedologici suggerivano di riferirne 6 al substrato marino, 16 ai depositi fluviali e 4 al sovrastante loess eolico. in particolare (fig. 5), i campioni relativi al substrato e al loess provengono dai sondaggi f2 ed e3, ubicati rispettivamente in corrispondenza al settore bb (sondaggio f2) e al versante sottostante (sondaggio e3); i depositi fluviali sono stati, invece, osservati nei campioni provenienti dai sondaggi s1, s2, s3 e s4 ubicati in corrispondenza al settore aa. i dati raccolti, schematizzati in tabella 1, possono così essere riassunti. il substrato marino (11 in fig. 4) è costituito, in percentuali circa confrontabili, da quarzo, mica bianca, serpentino, glaucofane, anfibolo verde scuro (hastingsite?), tremolite, epidoti e granato, con ridotte quantità di minerali accessori. i depositi fluviali (22aa e 22bb in fig. 4) sono formati in netta prevalenza da quarzo, mica bianca e clorite e da minori quantità di biotite, glaucofane, tremolite, anfibolo verde scuro (hastingsite?) e minerali opachi, con trascurabili quantità di minerali accessori. in particolare i diversi campioni di depositi fluviali, riferibili sia alla facies sabbiosa (termine 22aa) sia a quella siltosa (termine 22bb), mostrano caratteristiche mineralogiche del tutto confrontabili tra loro: l’unica differenza significativa è rappresentata dalla diffusa presenza di incrostazioni di ossidi idrati sui granuli dei campioni riferibili al termine 22bb. il loess eolico (33 in fig. 4) risulta costituito essenzialmente da quarzo, mica bianca e carbonati, con quantità nettamente subordinate di clorite, glaucofane, tremolite, biotite, epidoti e minerali opachi. i tre termini costituenti la successione stratigrafica risultano, quindi, ben differenziabili tra loro anche dal punto di vista mineralogico. ee)) ccaarraatttteerrii ppeeddooggeenneettiiccii al fine di valutare il grado di alterazione dei depositi fluviali presi in esame è stato condotto uno studio impiegando i metodi di analisi chimica del suolo (ministero delle politiche agricole e forestali, 2000): i parametri presi in considerazione sono la tessitura, il contenuto carbonatico e la quantità e natura degli ossidi di fe, che rappresentano i principali indici di maturità del suolo (arduino et al., 1984; jackson, 1965). i campioni erano costituti prevalentemente da particelle <2mm e sono stati previamente essiccati a 40 °c prima di essere analizzati. in particolare la valutazione della tessitura è stata effettuata mediante sedimentazione di sospensioni acquose disperse con na esametafosfato (metodo della pipetta); il tenore in carbonato totale è stato determinato dosando volumetricamente la co2. il contenuto totale di fe, al, ni (fet, alt, nitt) è stato dosato mediante spettrofotometria in assorbimento atomico (saa) negli estratti ottenuti previo attacco con miscela regia dei campioni macinati con mortaio (<0.5mm); la caratterizzazione degli ossidi di fe è stata condotta mediante alcune estrazioni chimiche selettive. in particolare l’estrazione degli ossidi di fe solubili in ossalato è stata eseguita secondo s c h w e r t m a n n (1964) e il contenuto di fe in soluzione (fe o) è stato misurato via saa. feo, per la selettività dell’estraente, può essere considerato derivato principalmente da ossidi e ossidrossidi di fe amorfi o a basso ordine cristallino. la quantità totale di ossidi di ferro di origine pedogenetica è stata stimata mediante la dissoluzione con ditionito citrato bicarbonato (boero & s c h w e r t m a n n , 1987); il fe e l’al in soluzione (fed e ald) sono stati dosati via saa. l’ald si assume derivi dalla sostituzione isomorfa del fe nel reticolo 181lembi di depositi fluviali ... fig. 6 curve granulometriche cumulative relative ai sedimenti marini del substrato (1), ai depositi fluviali (2) e al loess eolico (3). cumulative texture curves of marine sediments (1), fluvial sediments (2) and aeolian loess (3). cristallino degli ossidi di fe. sono state condotte anche estrazioni di controllo con solo citrato bicarbonato (fecb e alcb) per tener conto del rilascio eventuale della matrice. nei rapporti di fed con fet e nei calcoli con ald è stata detratta la quantità corrispondente a fecb e alcb rispettivamente. poiché fed deriva dagli ossidi di fe pedogenetici in toto, la differenza fed-feo è verosimilmente ascrivibile alla goethite avendo i sedimenti una colorazione giallastra (variabile tra 10yr 4,5/4 e 7,5yr 4/4); il rapporto (fed/fet è considerato un indice strettamente correlato con l’intensità dei processi pedogenetici con valori prossimi all’unità per suoli molto alterati e prossimi allo zero in assenza di ossidi di ferro pedogenetici (cornell & schwertmann, 1996). la quantità di goethite è stata quindi calcolata assumendo questo minerale come unica fase cristallina ed attribuendole la differenza fed-feo. complessivamente sono stati studiati undici campioni provenienti dai sondaggi s1 e s4 (fig. 5): i risutalti ottenuti sono compendiati in tab. 2. prendendo in esame il sondaggio s4 si osserva che il loess eolico (campione 1) è caratterizzato da un contenuto in carbonati totali del 9% che contrasta con quello dei depositi fluviali sottostanti (campioni 2, 3 e 4), con un contenuto di carbonati del 1-2%. solo alla base della successione fluviale (campione 5) si ha un contenuto di carbonati del 7%: tale elevata quantità potrebbe essere attribuita alla precipitazione del carbonato di ca di origine secondaria alimentata dalla dissoluzione di quello contenuto nel loess sovrastante. un’altra ipotesi è che i depositi fluviali sabbiosi basali contengano carbonato in quanto al momento della sepoltura ad opera dei depositi fluviali sovrastanti, i processi pedogenetici erano appena iniziati, come testimonierebbe anche il modesto grado di alterazione stimato dal rapporto fed/ fet di 0.36. 182 m.g. forno et alii tab. 1 composizione mineralogica media dei campioni presi in esame. i simboli utilizzati sono i seguenti: xxxx = minerali prevalenti; xxx = molto abbondanti; xx = abbondanti; x = poco abbondanti; = scarsi; -= molto scarsi; / = assenti. mineralogical composition of the studied samples. symbols for lithotype abundance are: xxxx = prevailing; xxx = very abundant; xx = abundant; x = poorly abundant; = scanty; -= very scanty; / = absent. mmiinneerraallii ssuubbssttrraattoo ddeeppoossiittii llooeessss mmaarriinnoo fflluuvviiaallii eeoolliiccoo quarzo xxx xxxx xxxx k-feldspato x / albite x / plagioclasio x / / mica bianca xxx xxxx xxxx sericite in aggregati x x clorite x xxxx x biotite x xx x serpentino xxx x epidoto xx xx glaucofane xxx xx x anf. verde scuro (hastingsite) xx xx / tremolite xx xx x cloritoide x / pirosseno onfacitico x x / carbonato in aggregati x x xxxx rutilo sagenitico (inclusioni) x x / granato xx / tormalina x minerali opachi (alterati) x xx x ss oo nn dd aa gg gg iioo cc aa mm pp iioo nn ii nn aa ttuu rraa dd ee ll dd ee pp oo ssii ttoo pp rroo ffoo nn dd iittàà ss aa bb bb iiaa gg ss aa bb bb iiaa ff ll iimm oo gg ll iimm oo ff aa rrgg iillll aa cc aa cc oo 33 ttoo tt ff ee dd ff ee tt ff ee oo ff ee dd //ff ee tt gg tt aa ll ss oo sstt (m ) (% ) (% ) (% ) (% ) (% ) (% ) (% ) (% ) (% ) (% ) (% ) (m o l% ) 1 lo e ss 8 ,3 0 -8 ,3 5 0 ,6 3 0 ,9 2 8 ,5 2 1 ,3 1 8 ,7 9 1 ,7 5 3 ,7 7 5 0 ,1 8 0 ,4 5 7 2 ,4 9 5 1 0 ,5 6 2 d e p . flu v. s ilt o si 8 ,7 0 -8 ,8 0 0 ,8 3 1 ,2 2 2 ,8 2 4 ,1 2 1 ,2 2 2 ,0 7 3 ,9 5 0 ,2 4 0 ,5 1 6 2 ,8 9 7 1 2 ,8 8 s 4 3 d e p . flu v. s ilt o si 9 ,5 0 -9 ,6 0 2 ,2 3 6 ,2 1 4 ,8 1 8 ,3 2 8 ,5 1 3 ,1 9 5 ,0 2 5 0 ,2 2 0 ,6 3 0 4 ,7 3 1 2 1 ,6 6 4 d e p . flu v. s a b b io si 1 0 ,5 0 -1 0 ,6 0 0 ,1 4 7 ,3 2 4 ,5 1 6 ,3 1 1 ,9 2 2 ,1 9 4 ,2 2 5 0 ,2 1 0 ,5 1 4 3 ,1 4 5 1 6 ,6 6 5 d e p . flu v. s a b b io si 1 1 ,7 0 -1 1 ,8 0 1 0 ,1 3 7 ,4 1 5 ,1 1 9 ,1 1 8 ,3 7 1 ,6 4 4 ,4 7 5 0 ,1 0 0 ,3 6 2 2 ,4 4 9 9 ,7 6 6 su b st ra to 1 4 ,7 0 -1 4 ,8 0 5 1 ,5 1 6 ,2 5 ,8 1 4 ,0 1 2 ,5 0 ,4 0 ,6 5 4 ,5 2 5 0 ,1 4 0 ,1 3 8 0 ,8 0 8 4 ,1 2 7 lo e ss 9 ,8 0 -1 0 ,0 0 0 ,6 7 1 ,3 2 ,3 9 ,3 1 6 ,5 1 1 1 ,5 8 3 ,6 2 5 0 ,1 6 0 ,4 3 1 2 ,2 5 1 1 0 ,0 8 8 d e p . flu v. s ilt o si 1 0 ,6 0 -1 0 ,7 0 2 ,6 5 4 ,0 6 ,1 1 2 ,8 2 4 ,4 1 2 ,3 1 3 ,7 5 0 ,2 6 0 ,6 1 1 3 ,2 6 5 1 6 ,2 4 s 1 9 d e p . flu v. s ilt o si 1 1 ,6 0 -1 1 ,7 0 1 ,6 5 8 ,6 8 ,0 1 0 ,4 2 1 ,4 0 2 ,8 4 4 ,9 5 0 ,2 5 0 ,5 7 0 4 ,1 1 9 2 0 ,9 6 1 0 d e p . flu v. s a b b io si 1 3 ,6 0 -1 3 ,7 0 8 ,0 4 1 ,4 2 7 ,4 1 4 ,2 9 ,0 1 9 1 ,3 5 2 ,9 0 ,1 4 0 ,4 6 0 1 ,9 2 8 9 ,5 7 1 1 d e p . flu v. s a b b io si 1 4 ,2 0 -1 4 ,3 0 5 ,3 5 0 ,0 2 2 ,3 1 4 ,8 7 ,7 2 1 1 ,1 9 2 ,9 5 0 ,1 9 0 ,3 9 6 1 ,7 4 3 8 ,7 2 1 2 su b st ra to 1 6 ,6 0 -1 6 ,7 0 5 5 ,7 2 3 ,4 4 ,5 9 ,8 6 ,7 8 0 ,2 8 4 ,7 0 ,1 1 0 ,0 5 5 0 ,2 6 9 3 ,3 3 t a b . 2 p ri n ci p a li ca ra tt e ri st ic h e f is ic h e e c h im ic h e d e i s e d im e n ti. (g = g ro ss a , f = f in e , c a c o 3 to t= c a rb o n a ti to ta li, g t= g o e th ite , a l s o st = s o st itu zi o n i i so m o rf e n e lla g o e th ite , a ltr e a b b re vi a zi o n i c fr . te st o ). m a in p h ys ic a l a n d c h e m ic a l ch a ra ct e ri st ic s o f th e s e d im e n ts . (g = c o a rs e , f = f in e , c a c o 3 to t= t o ta l ca rb o n a te s, g t= g o e th ite , a l so st = i so m o rp h o u s s u b st itu tio n o f a l fo r f e i n t h e g o e th ite , o th e r a b b re vi a tio n s se e t e xt ). il loess eolico (campione 1) si caratterizza anche per un contenuto di fet inferiore rispetto ai depositi fluviali (campioni 2, 3, 4 e 5) (3.8 versus 4.4%): questi ultimi appaiono decisamente più alterati (mediamente fed/ fet 0.58) rispetto al loess (fed/ fet 0.46) e la goethite risulta essere l’unico ossido di ferro cristallino presente. si osserva inoltre come complessivamente i depositi fluviali siltosi (campioni 2 e 3) risultino più alterati (media fed/ fet 0.58) di quelli sabbiosi sottostanti (campioni 4 e 5) (media fed/ fet 0.42): nei primi infatti anche la goethite è caratterizzata da un elevato grado di al sostituzione (16 mol % versus 13). i depositi fluviali si differenziano anche rispetto al substrato marino (campione 6) per un maggior contenuto di carbonato (media 3% versus 0.4) e per un grado di alterazione nettamente maggiore (media fed/ fet 0.50 versus 0.14). nel sondaggio s1 si evidenzia come la copertura loessica (campione 7) sia caratterizzata dall’11% di carbonato e contrasti con i depositi fluviali siltosi sottostanti (campioni 8 e 9) pressoché decarbonatati. i depositi fluviali inferiori (campioni 10 e 11) contengono invece mediamente il 20% di carbonati, in analogia ai sedimenti marini basali, anch’essi carbonatici (8%): la maggiore vicinanza di questi depositi al substrato marino complica le ipotesi genetiche del carbonato rispetto al sondaggio s4, pur non perdendo la netta differenziazione in termini di alterazione. i depositi fluviali siltosi (campioni 8 e 9), caratterizzati da un rapporto fed/ fet pari a 0.59, risultano caratterizzati da un grado di alterazione maggiore sia rispetto ai depositi fluviali sabbiosi sottostanti (campioni 10 e 11), sia rispetto alla copertura loessica (campione 7), entrambi caratterizzati da un rapporto fed/ fet pari a 0.43. il maggior grado di alterazione di questi sedimenti si traduce in una maggior quantità di goethite (3.70 %) avente in media 18 moli % di al sostituzione, rispetto ai depositi fluviali sabbiosi sottostanti aventi un minore tenore di goethite (2%) con 10 moli % di al sostituzioni. sulla base dello stesso indice di alterazione il substrato marino (campione 12) sottostante la successione fluviale risulta sostanzialmente inalterato. l’insieme delle osservazioni riportate consente di ipotizzare come nei sondaggi presi in esame si sviluppi una successione stratigrafica caratterizzata, anche dal punto di vista pedologico, da tre diversi termini sovrapposti. tale successione risulta costituita alla base da sedimenti privi di evidenti segni di alterazione, corrispondenti al substrato marino, nella parte intermedia da sedimenti caratterizzati da una notevole concentrazione di ossidi di fe di origine pedogenetica, corrispondenti ai sedimenti fluviali, e nella parte superiore da sedimenti sensibilmente carbonatici, corrispondenti al loess eolico. come indicato nella letteratura (jackson, 1965) la presenza di ossidi di fe pedogenetici è infatti tipica dei suoli che hanno subito intensi processi di alterazione; la presenza dei carbonati è invece indice di uno stadio iniziale nei processi di pedogenetici. la netta disomogeneità del grado di alterazione tra i depositi fluviali e il substrato marino suggerisce che quest’ultimo sia stato decapitato della parte pedogenizzata ed è coerente con la presenza di una superficie di erosione alla base dei depositi fluviali. l’alterazione dei depositi fluviali, pur inibiti nel loro sviluppo dal contatto con il loess eolico, documenta la presenza di intensi processi pedogenetici soprattutto nella sua porzione più superficiale. per quanto riguarda il significato cronologico dei suoli descritti i processi di alterazione cui sono stati sottoposti i depositi fluviali di entrambi i sondaggi sarebbero collocati nella parte superiore del pleistocene medio secondo la relazione di arduino et al. (1984) che, prendendo in considerazione la successione pedostratigrafica di alcuni terrazzi dell’alta pianura piemontese opportunamente calibrata con elementi stratigrafici di altra natura, lega il grado di alterazione del suolo attraverso lo studio degli ossidi di fe con l’età del deposito fluviale sottostante. e’ da sottolineare che le considerazioni prima riportate si riferiscono a successioni fluviali affioranti, tuttora interessate da fenomeni di alterazione: trattandosi invece, nel caso in esame, di sedimenti sepolti i dati misurati si riferiscono all’intervallo di tempo anteriore alla copertura da parte del sovrastante loess eolico. 55.. ccoonnssiiddeerraazziioonnii ccoonncclluussiivvee la campagna geognostica, effettuata nell’ambito del progetto di ristrutturazione e nuova edificazione dell’area di villa gualino (figg. 1 e 2), ha offerto l’opportunità di studiarne in dettaglio l’immediato sottosuolo. l’insieme dei dati, suggeriti in un primo momento dai risultati delle prove penetrometriche (fig. 3) e successivamente controllati in modo più circostanziato tramite l’esame delle stratigrafie dei sondaggi, individua la presenza di uno spessore rilevante di depositi incoerenti: tale spessore, compreso a seconda dei punti tra 10 e 15 m, risulta anomalo per l’area collinare dove in genere si sviluppa un’esigua copertura di natura colluviale e/o eolica direttamente sulle formazioni marine del substrato. i risultati dell’indagine effettuata suggeriscono invece che in corrispondenza al settore aa dell’area in esame, tra il substrato (11 in figg. 4b e 4c) e questa copertura (33 e 44), si abbia l’interposizione di sedimenti fluviali (22). a suggerire questa interpretazione valgono essenzialmente la natura erosionale della superficie di appoggio, osservata nelle diverse stratigrafie prese in esame e sottolineata dai dati pedologici, la giacitura discordante rispetto al substrato marino e la geometria complessivamente lenticolare del corpo sedimentario, evidenziata tramite la correlazione dei profili (fig. 5): la base concava, corrispondente a una depressione modellata nel substrato, sembrerebbe testimoniare la presenza di un canale fluviale, mentre la superficie sommitale suborizzontale corrisponderebbe ad un lembo di pianura alluvionale, successivamente terrazzata dal corso d’acqua e sepolta dai sedimenti eolici; anche le osservazioni sedimentologiche, e in particolare il confronto tra la netta stratificazione piano-parallela del substrato e la mancanza di una evidente stratificazione dei termini alluvionali, sono in accordo con lo sviluppo di un canale fluviale interessato da fenomeni di esondazione. il modellamento fluviale del settore aa è anche suggerito dalla distribuzione della successione alluvionale, limitata appunto a un lembo subpianeggiante, e dall’analogia di facies rispetto ad altri depositi riferibili alla successione fluviale terrazzata individuata sul versante occidentale della collina di torino. inoltre il lembo di villa gualino si raccorda altimetricamente con altri lembi conservati sulle diverse dorsali dello stesso ver183lembi di depositi fluviali ... sante che rappresentano i relitti di una originaria superficie terrazzata, caratterizzata da una debole inclinazione verso nord (boano & forno, 1997). la differenziazione della successione fluviale è legata ai diversi caratteri rispetto alle formazioni marine e ai sedimenti eolici e colluviali, evidenziati tramite lo studio dei campioni raccolti (fig. 5). in particolare, per quanto riguarda l’aspetto tessiturale, i sedimenti alluvionali presentano natura essenzialmente sabbiosa nella parte inferiore e siltoso-argillosa in quella superiore e sono caratterizzati da scarsa selezione (22 in fig. 6): differiscono, quindi, sia dalle sottostanti formazioni marine, costituite prevalentemente da alternanze sabbiose e ghiaiose (11 in fig. 6), sia dalla sovrastante copertura eolica, con tessitura siltosa omogenea (33 in fig. 6). dal punto di vista mineralogico i sedimenti fluviali sono formati essenzialmente da quarzo, mica bianca e clorite, con minori quantità di biotite, epidoto, glaucofane, hastingsite, tremolite e minerali opachi: i diversi campioni mostrano tra loro una costituzione omogenea ed invece differiscono dai sedimenti marini, che sebbene caratterizzati dagli stessi costituenti principali (quarzo e mica bianca) mostrano anche notevoli quantità di serpentino, glaucofane, hastingsite, tremolite e granato (tab. 1). marcate sono anche le differenze di tali sedimenti rispetto alla copertura eolica, che risulta caratterizzata da una minore varietà mineralogica e da un elevato contenuto carbonatico. ulteriori differenze tra i diversi termini riguardano la diffusione nel substrato marino e nel loess eolico di gusci carbonatici, corrispondenti rispettivamente a microfossili marini e a frammenti di molluschi continentali, assenti invece nei sedimenti alluvionali. i dati pedologici indicano inoltre la maggiore alterazione dei sedimenti fluviali sia rispetto ai termini marini, privi di evidenti segni di alterazione, sia nei confronti del loess eolico, caratterizzato essenzialmente da fenomeni di lisciviazione dei carbonati (tab. 2): confermano quindi la deposizione della successione fluviale al di sopra di una superficie erosionale, responsabile della troncatura dei suoli sviluppati sul substrato. gli stessi dati, in assenza di informazioni stratigrafiche dirette, suggeriscono l’attribuzione dei suoli sviluppati su quest’ultima alla parte superiore del pleistocene medio, in analogia ad altri suoli rinvenuti nel settore piemontese (arduino et al., 1984); confermerebbero inoltre l’attribuzione del loess eolico al tardo pleistocene superiore già ipotizzata in precedenza (forno, 1979). i risultati dell’indagine suggeriscono invece che il settore bb, caratterizzato solo dalla presenza di sedimenti colluviali, corrisponda ad una superficie almeno in parte antropica: in particolare tale settore sarebbe stato interessato da lavori sia di accumulo, in corrispondenza alla superficie su cui sorge la residenza di villa gualino, sia di spianamento, in corrispondenza all’esteso piazzale antistante. la composizione mineralogica dei sedimenti fluviali fornisce alcune utili indicazioni sul bacino di provenienza del corso d’acqua. in particolare, la mineralogia sembrerebbe escludere l’apporto dei collettori del bacino piemontese meridionale, in quanto sono assenti o molto scarsi i granuli di plagioclasio provenienti dal massiccio migmatitico dell’argentera e i granuli di lave acide riferibili alle coperture vulcaniche e vulcanoclastiche permiane. questa ipotesi è confortata dalle conoscenze riguardanti sia l’andamento, nello stesso intervallo di tempo, del reticolato idrografico del bacino piemontese meridionale, caratterizzato come si è detto da un collettore impostato in corrispondenza al versante meridionale della collina di torino (aa in fig. 1), sia la natura dei clasti dei depositi ad esso associati (compagnoni & forno, 1992; carraro et al., 1995). la composizione mineralogica è invece compatibile con un’alimentazione dai corsi d’acqua del bacino piemontese settentrionale provenienti dal settore alpino, caratterizzati dall’abbondanza dei clasti della zona sesia-lanzo e del complesso dei calcescisti con pietre verdi (bb in fig. 1): tale provenienza è suggerita dall’abbondanza dei minerali caratteristici sia delle metaofioliti in facies eclogitica della zona piemontese interna (glaucofane, hastingsite, epidoto, onfacite) sia dei metasedimenti o calcescisti (quarzo e miche chiare). la scarsità di granato, che rappresenta in associazione con l’onfacite il minerale più tipico delle eclogiti, potrebbe essere legata alla densità di questo minerale che ne avrebbe favorito la concentrazione nelle frazioni più grossolane, non rappresentate nei sedimenti fluviali in esame. l’insieme degli elementi mineralogici suggerisce essenzialmente il contributo del f. dora riparia, in cui queste rocce sono particolarmente diffuse, piuttosto che delle valli di lanzo, dove si ha anche una notevole distribuzione delle peridotiti più o meno serpentinizzate del massiccio ultrabasico di lanzo, totalmente assenti nei sedimenti in esame. rriinnggrraazziiaammeennttii gli autori ringraziano f. carraro e g. b. castiglioni per la revisione critica del manoscritto. lavoro realizzato con il contributo finanziario dei servizi tecnici di prevenzione della regione piemonte. llaavvoorrii cciittaattii arduino e., barberis e., carraro f. & forno m. g. (1984) estimating relative ages from ironoxide/total-iron ratios of soils in the western po valley, italy. geoderma, 3333, 39-52, amsterdam. boano p. & forno m. g. (1997) evoluzione morfologica quaternaria del versante occidentale della collina di torino. geoitalia, 1° forum fist, 1997, 22, 221-222. boano p., carraro f., forno m. g., giardino m., lozar f., lucchesi s., perotto a., piana f. & polino r. (2000) l’evoluzione recente della collina di torino: un esempio di interazione tra attività geodinamica e morfogenesi. in: carulli g. b. & longo salvator g. (eds.) riassunti delle comunicazioni orali e dei posters della 80a riun. est. soc. geol. it. (trieste, 6-8 settembre 2000), ed. univ. trieste, 81-83. boero v. & schwertmann u. (1987) iron oxide mineralogy of terra rossa and its genetic implications. geoderma, 4444, 319-327. bonsignore g., bortolami g. c., elter g., montrasio a., petrucci f., ragni u., sacchi r., sturani c. & zanella e. (1969) note illustrative della carta 184 m.g. forno et alii geologica d'italia, fogli 56 e 57 "torino e vercelli". iia ed., serv. geol. it., roma, 96 pp. bortolami g. c., crema g. c., sacchi r., sturani c. & zanella e. (1969) foglio 56 "torino" della carta geologica d'italia alla scala 1:100.000. iia ed., serv. geol. it., roma. carraro f. (1976) diversione pleistocenica nel deflusso del bacino piemontese meridionale: un’ipotesi di lavoro. gruppo di studio del quaternario padano, 33, 89-100. carraro f., forno m. g. & valpreda e. (1982) field trip in northern italy. guidebook. september 15th. piedmont: asti area. international geological correlation programme project 73/1/24 “quaternary glaciations in the northern hemisphere”. final session. september 1/17th 1982. franceitaly. litografia massaza & sinchetto, 24 pp. carraro f., collo g., forno m. g., giardino m., maraga f., perotto a. & tropeano d. (1995) l'evoluzione del reticolato idrografico del piemonte centrale in relazione alla mobilità quaternaria. in: polino r. & sacchi r. (eds.) atti del convegno "rapporti alpi-appennino" e guide alle escursioni (peveragno (cn), 31 maggio-1 giugno 1994). accademia nazionale delle scienze, 1144, 445-461. compagnoni r. & forno m. g. (1992) significato geologico di depositi fluviali ghiaiosi pleistocenici medi nella collina di torino. il quaternario, it. journ. quatern. sc., 55, 105-122. cornell r. m. & schwertmann u. (1996) the iron oxides. vch, weinheim, 573 pp. forno m. g. (1979) il “loess" della collina di torino: revisione della sua distribuzione e della sua interpretazione genetica e cronologica. geogr. fis. dinam. quatern., 22, 105-124. forno m. g. (1990) aeolian and reworked loess in the turin hills (northwestern italy). quatern. int., 55, 81-87, oxford. jackson m. l. (1965) clay transformations in soil genesis during the quaternary. soil sc., 9999, 15-22. ministero delle politiche agricole e forestali (2000) metodi di analisi chimica del suolo. franco angeli, milano. schwertmann u. (1964) differenzierung der eisenoxide des boden durch extraktion mit ammoniumoxalat-loesung. z. pflanzenernähr. düngung bodenkunde, 110055, 194-202. 185lembi di depositi fluviali ... ms. ricevuto il 23 aprile 2002 testo definitivo ricevuto il 30 luglio 2002 ms. received: april 23, 2002 final text received: july 30, 2002 impaginatocarobene ffoorrmmee tteerrrraazzzzaattee rreelliittttee ddii ggeenneessii mmaarriinnaa lluunnggoo llaa ccoossttaa lliigguurree ttrraa ggeennoovvaa ee ssaavvoonnaa ((lliigguurriiaa oocccciiddeennttaallee)) ll.. ccaarroobbeennee && mm.. ffiirrppoo università degli studi di genova dipartimento per lo studio del territorio e delle sue risorse (dip.te.ris.) corso europa, 26 16132 genova riassunto vengono esaminati in maniera organica i terrazzi marini del tratto di costa genova – savona; essi si presentano in generale come relitti, rimodellati da una forte e prolungata erosione. lo studio ha permesso infatti di collegare la genesi dei terrazzi all’evoluzione plio-quaternaria di questo settore costiero, che presenta sedimenti del pliocene inferiore oggi affioranti fino alla quota di 100 200 m. le considerazioni dedotte dalla presente ricerca riguardano aspetti morfologici, stratigrafici e tettonici, così sintetizzabili: 1) sono riscontrabili varie tipologie di forme terrazzate relitte; 2) le superfici più basse sono correlabili in 3 ordini di terrazzi, probabilmente quaternari, che occupano una fascia costiera fino alla quota di 145 m; 3) i relitti più alti sono mal correlabili tra loro, si presentano molto erosi, sono probabilmente pliocenici e occupano una fascia costiera più interna fino a circa 400 m di quota; 4) le superfici più basse di 145 m conservano quasi sempre depositi marini costieri pedogenizzati; 5) il sollevamento costiero ha prodotto un basculamento, ben riconoscibile nel terrazzo che si alza progressivamente in quota da 60 m (savona) a 145 m (genova); 6) la fascia costiera terrazzata può essere suddivisa in settori trasversali diversi tra loro per caratteri morfologici e geologici; 7) l’età dei terrazzi è ipotizzabile in maniera indiretta in base a considerazioni sullo stato di erosione che essi presentano e in base ai rapporti con i depositi del pliocene inferiore; 8) il sollevamento si è manifestato in due fasi principali caratterizzate da differente velocità; 9) la linea di costa ad andamento rettilineo circa ene–oso (tratto savona voltri) denuncia il controllo tettonico sulla separazione tra l’area di terraferma sollevatasi nel plio-quaternario e l’area di piattaforma in subsidenza. abstract relict terraced landforms of marine origin along the coast between genoa and savona (liguria, italy) a geological survey of the coast between genoa and savona was carried out with the aim of fully describing, correlating and presenting all the ancient terraced landforms and deposits associated with ancient sea levels that rise to more than 300 m above actual mean sea level. the area falls within the eastern sector of the ligurian alps, where a number of metamorphic units crop out: the savonese and arenzano crystalline massifs (paleozoic continental crust) and the voltri group (oceanic crust and serpentinised peridotites) (fig. 1). the coastal terraces examined had previously been studied by issel (1883), rovereto (1939), limoncelli and marini (1969), cortemiglia (1983), none of whom was, unfortunately, able to give a complete, systematic description of the morphology or deposits or adequate correlations between the terraces. the survey obtained the following information: 1) the relics associated with ancient marine terraces are of various types: terraced surfaces that stretch along the main ridges (that fall directly to the sea), the outer edge and inner margin of which are identifiable; sub-horizontal parts of ridge delimited by outer edge and inner margins; successions of culminations of similar altitude aligned along the main ridges; isolated remains of summital terraced surfaces lacking inner margins; terraced surfaces running along the coast and corresponding to a marine platform covered by thick marine and continental deposits. the “inner margin” is some metres higher than the ancient coastline (terrace 25 m above mean sea level in tab. 1) (fig. 11). 2) three orders of terraces were identified. the first order consists of clearly correlatable terraced surfaces whose inner margins rise to an altitude of from 60 m at savona to 145 m a.s.l. at genoa; there is almost always a weathered marine deposit on these surfaces. the second order, only clearly identifiable in sector 9, consists of small terraced remains with inner margins 60 m a.s.l., on which weathered pebbly deposits are preserved. terraced surfaces with inner margins 35 m a.s.l., identified in the less uplifted sector 1, could belong to this order. the third order consists of terraced surfaces with inner margins at 25 m a.s.l., referring to two marine platforms (fig.11), the more high of the two with an inner margin at 17 m a.s.l. and the lower one with an inner margin at 7 m a.s.l. both platforms are overlaid by marine deposits and do not seem to show regional tilting. 3) along the stretch of coast surveyed it was also possible to identify terraced relics higher than the order of terraces between 60 m and 145 m described above. these relics have an average width of about 450 m and inclinations of about 2°; they are distributed between 100 and 400 m a.s.l. and are difficult to correlate as they are very eroded (plate i) and without deposits. a better understanding of these relics will require further studies. 4) both marine and continental deposits were identified on the terraced surfaces included in the four orders cited above. the marine deposits have a maximum thickness of 4-5 m and mainly consist of gravel with rounded pebbles, often flattened and imbricated towards the sea; those at natta (fig. 5) and voltri (plate i) are particularly well preserved. the deposits are always strongly weathered (red, yellowish red, reddish brown; 2.5 yr and 5 yr). 5) the uplift of the ancient terraced surface caused the tilting that is attested by the order of terraces that varies progressively in height from 60 m a.s.l. at savona to 145 m at genoa (orange coloured terrace in plate i). it is more difficult to establish the degree of tilting of the terraces above this order. the lower orders (+7 m and +17 m) seem to have remained sub-horizontal. 6) the coastal area surveyed can be divided into different sectors (fig. 2) on the basis of its general morphology and the lithology of the substratum. furthermore, the variation in the height of the terraces suggests that some sectors have been separated by neotectonic transverse faults (e.g. sector 4, tab. i). 7) the age of the terraces has been approximately calculated on the basis of the reliable data available: the early pliocene is the most recent part of the substratum which is preserved in scattered relics along the coast at less than 100 m a.s.l; the terraces lying above the order at 60÷145 m a.s.l. are very eroded and without deposits; the terraced order lying at 60÷145 m a.s.l. formed after the early pliocene emersion; il quaternario italian journal of quaternary sciences 1155(1), 2002, 53-68 11.. iinnttrroodduuzziioonnee con la presente ricerca, condotta sia sul terreno sia mediante l'analisi delle carte topografiche alla scala 1:5.000 della regione liguria, si è cercato di documentare, rappresentare e correlare per la prima volta tutte le forme plioquaternarie derivanti da alti livelli di stazionamento del mare nel settore costiero compreso tra genova e savona. con opportuni simboli è stato evidenziato anche l'aspetto che tali forme presentano: un primo gruppo è infatti costituito dai relitti dei terrazzi più alti per i quali non ci sono prove dirette e sicure della loro origine marina, che hanno subìto una fortissima erosione e che oggi corrispondono a crinali stretti, irregolari, leggermente inclinati verso mare, privi di coperture detritiche. un secondo gruppo comprende relitti di terrazzi a quote intermedie, meglio conservati, in cui l'erosione ha frammentato l'originaria disposizione parallela alla costa e ha distrutto in parte, a volte totalmente, l'eventuale deposito marino. il terzo gruppo infine comprende superfici marine a quote basse, disposte fronte mare, dove il sedimento marino è stato poco eroso ed anzi coperto da spessi depositi colluviali o da conoidi detritiche. tale rappresentazione concorda bene anche con l'età relativa da attribuire a tali forme relitte, in quanto le più alte e le più erose sono le più antiche; le più basse, protette dai depositi continentali di piede di versante, sono le più recenti. poco o nulla è emerso tuttavia sull’età dei terrazzi, per la mancanza di reperti databili. le interpretazioni cronologiche proposte nelle conclusioni sono state pertanto ricavate indirettamente utilizzando i dati certi in possesso e alcune ipotesi. lo studio dei terrazzi marini risale in liguria alla fine dell' 800; sono infatti issel (1883 e 1911) e successivamente rovereto (1939) i primi due autori a descrivere forme e depositi legati all'azione del mare lungo tutta la costa ligure, allora in gran parte non ancora urbanizzata. dal 1939, anno in cui venne pubblicato il volume di rovereto "liguria geologica", agli anni 1980 sono rari i lavori su questo argomento; ricordiamo in particolare limoncelli & marini (1969). all'inizio degli anni '80 il progetto finalizzato "neotettonica" dà nuovo impulso alle ricerche; sono infatti di quel periodo i lavori di cortemiglia (1983) che propone un quadro sinottico di tutte le antiche linee di riva della liguria, e di fanucci & tedeschi (1983) sui terrazzi marini del foglio 82 genova (scala 1:100.000). successivamente fanucci (1987) presenta una completa rassegna delle conoscenze sulle linee di riva della fascia ligure costiera emersa legando queste ultime alle osservazioni, che in quegli anni si stavano raccogliendo, sulla piattaforma continentale. bisogna poi passare agli inizi degli anni ‘90, quando alcuni cantieri aperti sul territorio ligure permisero accurati rilevamenti geologici, morfologici e stratigrafici che portarono alla stesura della nota di carobene & firpo (1994). 22.. iinnqquuaaddrraammeennttoo ggeeoommoorrffoollooggiiccoo ddeell ttrraattttoo ddii ccoossttaa ssttuuddiiaattoo 22..11.. ccaarraatttteerrii ggeeoollooggiiccii l’area di studio assume particolare interesse in quanto comprende il tratto orientale della catena alpina ligure, separata ad est da quella appenninica dalla zona sestri-voltaggio, comprendente: l’unità triassico-liassica di monte gazzo-isoverde, l’unità cravasco-voltaggio e l’unità del monte figogna; quest’ultima zona compare solo parzialmente in corrispondenza del settore 9 (fig.2). il massiccio cristallino savonese, il massiccio cristallino di arenzano e il gruppo di voltri rappresentano le tre unità alpine presenti nell'area; queste unità tettoniche da un punto di vista paleogeografico appartengono rispettivamente: le prime due al basamento continentale europeo pre-carbonifero superiore del dominio brianzonese ligure, l'ultima a quello oceanico del dominio piemontese ligure (s.g.i., 1991). il basamento polimetamorfico del dominio brianzonese rappresenta la crosta continentale paleozoica delle alpi liguri ed è costituito da rocce di crosta continentale che hanno subìto processi metamorfici di grado elevato. le rocce che affiorano nell'area di studio sono: anfiboliti e gneiss, paragneiss, micascisti ed ortogneiss (fig.1). le metaofioliti del dominio piemontese ligure rappresentano una crosta oceanica sviluppatasi nel giurassico attraverso processi che hanno portano ad una progressiva risalita del mantello astenosferico con conseguenti processi di fusione parziale; i fusi così 54 carobene-firpo the lower terraces, including that lying at 60÷145 m a.s.l., have better preserved surfaces on which it is possible to observe both marine and continental deposits. the absence of middle and late pliocene sediments and pleistocene shelf deposits along the stretch of coast surveyed would suggest that the uplifting of the early pliocene bathyal clays was very rapid and largely finished during the pliocene. the very eroded highest terraced remains, visible today as narrow sub-horizontal ridges without deposits, can be dated to this period. instead, the uplift would have proceeded very slowly in the quaternary, lifting the early pliocene layers to their present-day height of about 100 m a.s.l.; the terrace that rises to an altitude of from 60 m at savona to 145 m at genoa also probably belongs to this period as it is relatively well preserved. the two lowest coastlines, at +7 m (attributed to ois 5e) and +17 m (attributed to ois 9 or 11) document a very slow rate of uplift, less than or equal to 0.05mm/yr. the terraces considered to be quaternary occupy a coastal stretch approximately 750 m wide and up to 145 m a.s.l. the oldest terraced relics, probably pliocene in age, occupy a more inland stretch, up to 400 m a.s.l. and are about 2 km wide. landward of these, the slopes rise rapidly towards the ligure-padano watershed line. parole chiave: morfologia costiera, pliocene, quaternario, terrazzi marini, tettonica quaternaria, liguria key words: coastal morphology, pliocene, quaternary, marine terraces, quaternary tectonics, liguria 55forme terrazzate relitte ... f ig . 1 s ch e m a g e o lo g ic o s e m p lif ic a to d e ll’ a re a s tu d ia ta . s im p lif ie d g e o lo g ic a l s ch e m e o f th e a re a s u rv e ye d . generati hanno originato rocce gabbriche e basaltiche che assieme alle rocce del mantello sono state coinvolte in fenomeni tettonici e successivamente ricoperte dai sedimenti marini pelagici silicei e carbonatici. le rocce mantelliche sono state dapprima serpentinizzate e successivamente, assieme ai gabbri ed ai basalti ed alle loro coperture sedimentarie oceaniche, hanno subìto una evoluzione metamorfica conseguente agli eventi orogenici alpini. i litotipi affioranti appartenenti a tale dominio sono: eclogiti, serpentiniti e serpentinoscisti, metagabbri e metabasiti, calcescisti e filladi. le unità citate sono state poi variamente coperte e sigillate trasgressivamente dai depositi sedimentari oligocenici (conglomerati e arenarie) del bacino terziario piemontese (b.t.p.) e dai sedimenti plioquaternari. il pliocene è rappresentato da argille giallastre e marne argillose grigie con intercalazioni sabbiose, ricche di macro e microfossili di mare profondo, conservate in maniera discontinua fino alle quote di 100-200 m in tutto il tratto di costa indagato, a testimonianza del sollevamento avvenuto a partire dalla fine del pliocene inferiore. infine il quaternario è rappresentato da alluvioni antiche e recenti terrazzate, coltri detritiche eluvio-colluviali, depositi ciottolosi e sabbiosi dei terrazzi marini. 22..22.. ccaarraatttteerrii ggeeoommoorrffoollooggiiccii per meglio comprendere il tratto di costa studiato occorre metterlo in relazione sia con la struttura geologica sia con un elemento di grande importanza morfologica rappresentato dallo spartiacque ligure-padano (l.p.). per agevolare la descrizione, la fascia costiera è stata suddivisa in 9 settori che si diversificano per caratteri geologici e morfologici generali. in essi i terrazzi vi compaiono con quota, stato di conservazione e numero di ordini differente. la suddivisione in settori è riportata in fig 2, mentre non compare in tav.i. in corrispondenza dei settori occidentali 1, 2 e 3, tra savona e varazze, lo spartiacque l.p. forma un grande arco concavo verso mare, allontanandosi dalla costa fino a 10-12 km e abbassandosi in quota fino ai 516 m del p.so del giovo. i terrazzi costieri risultano discretamente conservati, ma frammentati lungo decine 56 carobene-firpo fig. 2 l’area indagata è stata suddivisa in nove settori differenti per gli aspetti morfologici generali, per i caratteri geologici del substrato e per le quote dei terrazzi. the area surveyed was divided into nine different sectors on the basis of its general morphological characteristics, the geological characteristics of the substratum and the height of the terraces above sea level. 57forme terrazzate relitte ... di crinali a causa della presenza di molti corsi d'acqua, tra cui i più importanti sono i torrenti letimbro, sansobbia e teiro. nell'area affiorano in prevalenza rocce metamorfiche del massiccio cristallino savonese e conglomerati oligocenici (b.t.p.). tra varazze e arenzano (settori 4, 5, 6), dove l'ordine intermedio dei terrazzi (tra 95 e 120 m di quota) si presenta meglio conservato e più continuo, lo spartiacque l.p. si avvicina alla costa fino a 4-5 km, formando un arco convesso verso mare tra il m. beigua (1287 m) e il m. reisa (1183 m). nell'area il substrato è rappresentato da serpentiniti ed eclogiti del gruppo di voltri; al suo interno i corsi d'acqua sono brevi e a forte pendenza (rio arenon, t.arrestra e rio lerone). tra arenzano e palmaro (settori 7 e 8), dove l'ordine intermedio dei terrazzi (tra 130 e 140 m circa di quota) risulta invece poco presente e mal conservato, lo spartiacque l.p. nuovamente si allontana fino a 6-7 km dalla costa, formando un arco tra m. reisa e il m. penello (995 m) e abbassandosi in quota fino ai 532 m del passo del turchino. nell'area affiorano rocce erodibili corrispondenti ai calcescisti del turchino; i corsi d'acqua importanti sono il t. cerusa e il t. leiro. la linea di costa attuale, inoltre, che nel tratto savona-voltri ha un andamento rettilineo circa eneoso (58°), assume la direzione ono-ese (105°) da voltri a recco. nel tratto di costa tra palmaro e genova lo spartiacque l.p. si distanzia bruscamente dalla linea di costa abbassandosi dai 995 m del m. penello ai 475 m del passo dei giovi. in quest'area affiorano le unità liguri sedimentarie giurassico-cretaciche, che non hanno permesso una buona conservazione delle superfici terrazzate; al suo interno è incisa, con andamento circa nne-sso, la grande valle del t. polcevera. pertanto esistono correlazioni tra lo stato di conservazione dei terrazzi e gli aspetti morfologici del versante ligure con la litologia del substrato; la linea di costa invece, pressoché rettilinea tra savona e voltri, non sembra risentire né dei cambiamenti litologici, né dell'andamento irregolare dello spartiacque l.p. questa particolarità testimonia il suo legame con l’evoluzione recente del margine continentale. 33.. mmeettooddoollooggiiaa ddii rraapppprreesseennttaazziioonnee i relitti di superfici terrazzate di genesi marina riconosciuti lungo il tratto di costa esaminato si presentano, nella maggior parte dei casi, come forme molto rimodellate da processi erosivi derivati dall' emersione e dal sollevamento della fascia costiera: la differente tipologia che tali relitti presentano è abbastanza ben riconoscibile dalle carte topografiche alla scala 1:5.000 della regione liguria, ma una verifica sul terreno è sempre stata necessaria. una buona conservazione delle originarie superfici terrazzate si osserva solamente al di sotto dei 30 m di quota, mentre a quote superiori l'erosione ha in gran parte smantellato le superfici; fa eccezione il grande terrazzo di arenzano, che presenta un lembo terrazzato con buona estensione areale tra i 90 e i 110 m di quota. i diversi aspetti osservabili sul terreno non sono adeguatamente descritti nelle proposte di segni convenzionali per la cartografia geomorfologica reperibili in letteratura (s.g.n.,1984), né d'altra parte è stato possibile dettagliare tutti gli aspetti morfologici e litologici (vedi ad es. carobene & ferrini, 1993) a causa della scala utilizzata per rappresentare il territorio esaminato in tav. i. e' stata pertanto creata una apposita simbologia (tav.i) che rappresentasse al meglio le situazioni di campagna, osservabili sia lungo i crinali che scendono direttamente verso mare, sia sui versanti fronte mare: 1) un primo tipo di relitto corrisponde a resti di superfici terrazzate rappresentabili con un simbolo areale; questo è delimitato a monte dal simbolo di margine interno e a valle dal simbolo di orlo esterno. 2) un secondo tipo di relitto corrisponde a tratti di crinale suborizzontali o inclinati di qualche grado verso mare. in questo caso la forma è rappresentata da una linea, delimitata a monte e a valle dai simboli di margine interno e orlo esterno. in alcuni casi esiste la combinazione tra il primo e il secondo tipo di relitti. 3) il terzo tipo di relitto è dato da tratti di crinale molto erosi, topograficamente riconoscibili da una serie di culminazioni consecutive di quota simile; in alcuni casi è stato possibile inserire anche i simboli di margine interno ed orlo esterno. 4) un quarto tipo di relitto è dato da lembi isolati di superfici terrazzate prive di margine interno; questa posizione sommitale può essere genetica o derivare dall’erosione del margine interno. 5) lungo determinati tratti di costa (ad es. tra voltri e palmaro ) sono presenti infine lembi terrazzati tra 5 e 25 m s.l.m., limitati lateralmente dall'incisione valliva dei corsi d'acqua; consistono in piattaforme di erosione marina ricoperte da spessi depositi marini e continentali (carobene & firpo, 1994). per tutte le superfici terrazzate e, in particolare, per questo tipo di forme terrazzate disposte lungo versanti fronte mare, bisogna osservare che il "margine interno" corrisponde sempre ad un "margine morfologico" riconoscibile cioè in base a osservazioni puramente topografiche. a causa della spessa copertura continentale di piede di versante, il margine interno della piattaforma marina può risultare più basso in quota di svariati metri, fino a 5-8 metri (carobene & firpo 1994) (v. paragr.4.3.). sulla carta sono stati infine riportati alcuni "punti quotati significativi", in quanto a volte corrispondono a culminazioni del rilievo aventi quote simili correlabili; esse potrebbero testimoniare relitti di antiche superfici terrazzate fortemente erose che, pertanto, si sviluppavano ad una quota certamente più alta. i lembi relitti di antiche superfici terrazzate vengono pertanto descritti morfologicamente nella tav. i allegata; il substrato nel quale è intagliata la superficie di erosione marina è riportato nello schema geologico (fig.1). eventuali campioni raccolti sono descritti nel testo. il corpo sedimentario rinvenuto sui lembi terrazzati viene analizzato sia mediante descrizione nel testo, sia mediante colonne stratigrafiche riportate in tav. i. vengono fornite sintetiche informazioni riguardanti aspetti strutturali e tessiturali, con particolare riguardo alla granulometria dei depositi, alla natura dei clasti, agli spessori e alla pedogenesi. molti depositi, direttamente poggianti sulla superficie del substrato, sono risultati di origine marina per le strutture sedimentarie osservate (quali l’embriciatura dei ciottoli verso mare), per la forma appiattita e per l'arro58 tondamento dei clasti e per la buona classazione del deposito. quando non sono presenti tutti questi elementi e in particolare i fossili, l’attendibilità della genesi marina è ovviamente minore. tuttavia in molti casi possono essere utili anche considerazioni geografiche: ad esempio il deposito ciottoloso a clasti arrotondati di un terrazzo sviluppato lungo costa, lontano da foci fluviali, può essere stato alimentato solamente dalle correnti marine costiere. le discontinuità tra il corpo sedimentario e il sottostante substrato antico, o tra il deposito marino e l'eventuale deposito continentale sovrastante, sono state descritte qualora visibili. in particolare la superficie di discontinuità inferiore è sicuramente marina per l'ordine di superfici terrazzate che risulta colorato in arancione in tav.i e per gli ordini più bassi. per quanto riguarda le superfici di discontinuità che separano i corpi marini dai sovrastanti corpi continentali, esse hanno sempre carattere erosivo; i due depositi sono in generale marcati da differente grado di pedogenesi. a quote superiori (relitti terrazzati alti) vi è assenza di depositi e le originarie superfici risultano fortemente rimodellate ed erose; la disposizione dei relitti rispetto alle valli fluviali fa ritenere che essi siano di origine marina; per quanto riguarda i relitti disposti a quote superiori ai 300 m non si può escludere che essi derivino dalla distruzione di superfici di spianamento continentale, legate ad alti livelli di base. poco o nulla si è potuto infine osservare sulle deformazioni presenti nei depositi, per lo scarso spessore degli stessi, o perché non si sono potute effettuare osservazioni sulla superficie di appoggio basale. fa eccezione il deposito marino di natta, interessato da evidenti strutture deformative. 44.. ggllii oorrddiinnii ddeeii tteerrrraazzzzii la mappatura di tutti i relitti di forme terrazzate ha permesso, in assenza di datazioni, una prima correlazione delle superfici che, da savona a genovapegli, salgono progressivamente in quota da un minimo di 60 m ad un massimo di 145 m (le quote si intendono riferite al margine interno). questo ordine di terrazzi è evidenziato in color arancio in tav. i e verrà descritto al paragrafo 4.2 . sono state inoltre facilmente correlate le superfici terrazzate aventi il margine interno alla quota di 25 m; esse appaiono colorate in giallo in tav.i. in realtà queste superfici possono corrispondere a due ordini distinti di terrazzi, in quanto esse corrispondono a coperture continentali che mascherano due piattaforme marine a diversa altezza (paragr. 4.3). tutti gli altri relitti di forme terrazzate sono stati descritti assieme nel paragrafo 4.1. (relitti terrazzati alti). questi relitti alti, cartografati fino alla quota massima di 395 m, appartengono sicuramente a più ordini distinti, ma possono avere anche significato diverso: i più alti potrebbero testimoniare (come sopra detto) antiche superfici di spianamento continentale; altre forme potrebbero essere imputabili all'erosione selettiva; altre a fatti tettonici locali. la loro corretta interpretazione e correlazione non risulta quindi facile. 44..11.. ii rreelliittttii tteerrrraazzzzaattii aallttii gli alti relitti di forme terrazzate, riconducibili a stretti crinali a debole pendenza o ad una successione di culminazioni di quota simile (fig.3), sono stati mappati lungo i crinali principali che scendono verso mare. tali relitti appaiono distribuiti in maniera non omogenea lungo la fascia costiera esaminata; le loro quote non risultano pertanto facilmente correlabili. la loro ampiezza varia da meno di 200 m ad oltre 1 km (ampiezza media di 458 m); le inclinazioni dei tratti esaminati variano da 0,5° a 5° circa (valore medio di 2°). questi dati suggeriscono che si tratta di relitti di antiche superfici terrazzate, come si evince anche dal confronto con i valori di inclinazione dei versanti che scendono al mare, presi in esame a partire dalla quota dei relitti più alti: detti valori variano in gran parte da 7° a 20° (valore medio di 10,5°). nel settore tra varazze ed albissola marina (vedi tav.i) i relitti 257-249 m (bric crava), 270289 m, 256-276 m (bric terra bianca) e 261-254 m carobene-firpo fig. 3 profilo di un relitto di terrazzo alto, che consiste in un crinale molto eroso, poco inclinato, caratterizzato da culminazioni di quota simile e da assenza di depositi. crinale di bric terra bianca (settore 3): p.c.profilo topografico del crinale con le culminazioni di quota 256 m, 262 m e 276 m. in alto: ricostruzione geometrica della superficie terrazzata (s.t.), avente inclinazione di 2,8° e ampiezza di 1020 metri; il margine interno (m.i.) è a 300 m e l’orlo esterno (o.e.) a 250 m s.l.m. le scarpate (s) hanno una inclinazione media di 23° a monte e di 10° a valle. profile of a relic of a high terrace consisting of a very eroded slightly-inclined ridge characterised by culminations of the same altitude without deposits. bric terra bianca ridge (sector 3): p.c. – topographic profile of the ridge with culminations of 256 m, 262 m and 276 m above s.l.. above: geometric reconstruction of the terraced surface. terraced surface (s.t.) with angle of inclination of 2.8° and width of 1020 m, the inner margin (m.i.) is 300 m above mean sea level and the outer edge (o.e.) 250 m. the landward slopes (s) have an average inclination of 23° and the seaward ones 10°. 59 (torre bregalla), sembrano ben correlabili a testimoniare un’originaria superficie estesa tra 250 e 300 m circa (esempio in fig.3: crinale di bric terra bianca), con ampiezza massima di oltre 2 km ed una inclinazione media valutabile in soli 1,4°: ad essa sembrano correlabili le cime (poste più ad ovest) di monte pasasco (286 m) e di bric della seia (297 m). tra questo ordine più alto e l'ordine di terrazzi 60÷145 m (che in quest'area occidentale della costa ha un margine interno che varia da quota di 65 a 75 m), si riconoscono almeno altri due ordini, uno con margine interno tra 110 e 130 m, l'altro posto ad una quota non superiore a 220 m. nel settore 4, tra punta della mola e il torrente arrestra, il relitto 252-280 m (bric berlese) sembra ben correlabile all'ordine più alto precedentemente descritto; in quest'area tuttavia esistono relitti ben evidenti di una superficie più alta lungo il crinale che dal santuario la guardia (406 m) sale al bricco della forca (472 m) con una pendenza media di 1,5°(su una distanza di 2,5 km). nel settore 5, tra il torrente arrestra e il rio lerone, è molto evidente la grande superficie di prato zanino, un relitto alto che si presenta arealmente ben conservato (e che sarà oggetto di successive ricerche); la quota di questa superficie appare ben correlabile con alcuni “punti quotati significativi” presenti nel settore 5: crinale 194-177, quote 181, 179 e 193 m (bric del campo), quote 192 e 213 (monte ciapin). nei quattro settori orientali (tra il rio lerone e pegli) appaiono sporadici relitti alti tra le quote di 395 e 320 m, poco estesi e mal conservati a causa dell'affiorare di rocce erodibili (calcescisti del turchino). infine nei settori 8 e 9, tra voltri e pegli, sono presenti ben correlabili “i punti quotati significativi” da ovest verso est: 198, 192 (bric croce), 206 (bric del vento), 203 (bric scaggie), 201, 200 (bric castello). 44.. 22.. ii tteerrrraazzzzii iinntteerrmmeeddii a) l’ordine dei terrazzi da +60 a +145 m considerate le differenze morfologiche e altimetriche che questo ordine presenta, la descrizione viene effettuata per singoli settori (fig.2). l'appartenenza ad un unico ordine è garantita dal progressivo innalzamento in quota del margine interno che sulla distanza di 32,5 km produce un dislivello di 85 m, pari ad un angolo di 0,15° (pendenza dello 0,26%). gli studi di neotettonica (c.n.r.,1987; cortellesi et al.,1979) che avevano preso in considerazione soprattutto il substrato, non avevano invece evidenziato tale basculamento. settore 1: riva destra del torrente letimbro il terrazzo, smembrato in vari lembi dalle incisioni vallive, è intagliato in substrato metamorfico. il margine interno si situa tra 60 e 70 m; la superficie terrazzata più ampia, mappata tra le quote estreme di 25 e 65 m per comodità di rappresentazione, in realtà sul terreno mostra uno scalino compreso tra i 35 e 45 m che indicherebbe un terrazzo più basso esteso tra 25 e 35 m. depositi significativi sono osservabili nelle zone vicine al margine interno della superficie più alta e sono costituiti da sedimenti sabbioso-ciottolosi, con clasti prevalentemente quarzosi aventi diametro di 10-15 cm; il deposito si presenta sempre molto alterato. in particolare la stratigrafia più dettagliata è stata descritta nello scantinato delle scuole corradini di savona (fig.4), sulla superficie terrazzata più ampia tra le cinque rappresentate sulla forme terrazzate relitte ... fig. 4 successione stratigrafica relativa al terrazzo 60÷145 m affiorante sulla superficie terrazzata in destra del torrente letimbro (settore 1), con margine interno a 65 m di quota (tav.i). (a)strato ciottoloso basale costituito da clasti quarzosi e metamorfici ben arrotondati e abbastanza sfericizzati, con diametro prevalente di 1 cm. la matrice è scarsa, sabbiosa. i radi clasti maggiori raggiungono i 10-15 cm; sono ben arrotondati e spesso appiattiti, disposti orizzontalmente o embriciati verso e o ese. il deposito, che può essere riferito ad una spiaggia, si presenta pedogenizzato(5yr-4/6). (b)strato sabbioso poggiante su una superficie di erosione. e’ costituito da sabbie grosse, mal classate, con lenti irregolari di clasti arrotondati aventi diametro inferiore a 1 cm e con radi clasti maggiori. il deposito, che si presenta gradato, sabbioso-pelitico nella parte alta, può essere riferito all’ambiente fluviale. (c)livello argilloso-siltoso grigio, privo di ciottoli, derivante da decantazione di materiale fine in ambiente fluviale. (d)deposito colluviale pelitico contenente clasti spigolosi con diametri prevalenti di pochi centimetri, alcuni fino a10 cm; radi i clasti arrotondati. il deposito si presenta pedogenizzato (7.5yr-6/6). stratigraphic succession associated with the terrace between 60 and 145 m which crops out of the terraced surfaces on the right of the letimbro torrent (sector 1), with inner margin 65 m above mean sea level (plate i). (a)basal pebbly layer consisting of well-rounded and fairly spherical quartzitic and metamorphic clasts with a predominant diameter of 1 cm. the matrix is poor and sandy. the largest scattered clasts, which are well-rounded and often disposed horizontally or imbricated towards the e or ese, measure up to 10-15 cm. the deposit, which can be associated with a beach, shows pedogenic alteration (5yr-4/6). (b)sandy layer lying on an erosion surface. it consists of badly-classed large grains, with irregular lenses of rounded clasts with a diameter of less than 1 cm and scarce bigger clast. the deposit, which is graded, sandy-pelitic towards the top, can be associated with a river environment. (c)grey clayey-silty level, without pebbles, coming from the settling of fine material in a river environment. (d)pelitic colluvial deposit containing angular clasts with a prevalent diameter of a few centimetres; some up to 10 cm; some rounded clasts. the deposit shows pedogenic alteration (7.5yr-6/6). fig. 5 in prossimità del margine interno del relitto terrazzato di natta (settore 3), uno scavo ha messo in luce la seguente stratigrafia: s = substrato oligocenico costituito da bancate di arenarie e conglomerati alterati e fagliati. il sovrastante deposito marino è suddiviso in: i = unità basale ghiaiosa, comprendente a) sabbia medio-grossa ghiaiosa, rubefatta, con granuli fino a 5 mm, che presenta localmente ciottoli arrotondati di 5–20 cm, a volte appiattiti ed embriciati a se; b) ghiaia fine, ben selezionata, senza matrice, con ciottoletti arrotondati di 3–8 mm; c) ghiaia sabbiosa, con ciottoletti arrotondati fino a 1,5 cm. le caratteristiche di questa unità sembrano indicare un deposito di battigia. ii = unità sabbiosa costituita da: a) alternanza di sabbie medie e molto grosse, con radi ciottoletti; b) sabbia grossa con livelli di ciottoli arrotondati aventi diametro massimo di 1–2 cm; l’unità indica un aumento della batimetria. iii = unità ghiaiosa, che in basso mostra: a) sabbie molto grosse e granuli fino a 3 mm, selezionate e prive di matrice; in alto passa a b) ghiaietto con ciottoletti arrotondati compresi tra 0,5 e 3 cm, senza matrice sabbiosa. le caratteristiche tessiturali indicano alta energia dell’ambiente. iv = unità sabbiosa, costituita da sabbie medie o grosse, massive, con rarissimi ciottoli appiattiti; è visibile per oltre un metro di spessore. essa indica probabilmente la spiaggia emersa. il deposito marino è ricoperto da un corpo detritico continentale sabbioso – ciottoloso d, molto arrossato (colori munsell 2.5 yr 4/6 e 10r 3/6), costituito da ciottoli in prevalenza spigolosi immersi in abbondante matrice sabbioso – limosa. questo deposito colluviale è a sua volta ricoperto da debris flow più recenti, pedogenizzati (colore munsell 5yr 4/6). close to the inner margin of the terraced relic of natta (sector 3), well has revealed the following stratification: s = oligocene substratum consisting of layers of sandstone and weathered conglomerates showing signs of faults. a marine deposit subdivided into: i = a gravely basal unit, consisting of: a) medium-large grained reddened gravely sand, with grains as fine as 5 mm, with scattered rounded pebbles of 5-20 cm, sometimes flattened and imbricated to the se; b) fine gravel, well-sorted, without matrix, with rounded pebbles of 3-8 mm; c) sandy gravel, with small rounded pebbles as small as 1.5 cm. the characteristics of this unit seem to indicate a shore deposit. ii = a sandy unit consisting of: a) an alternation of medium and very coarse sands with small scattered pebbles; b) coarse sand with layers of rounded pebbles with a maximum diameter of 1-2 cm. this unit indicates an increase in the bathymetry. iii = a gravely unit which passes from a) very coarse sands and fine sands with grain as fine as 3 mm, sorted and without matrix in its lower level, to b) fine gravel with rounded pebbles between 0.5 and 3 cm, without sandy matrix, in its upper level. the textural characteristics indicate a high-energy environment. iv = a sandy unit which is visible for over a metre in thickness and consists of massive medium and coarse sands with very occasional flattened pebbles. this probably indicates an emerged beach. the marine deposit is covered by a layer of sandy-pebbly continental detritus, very reddened (munsell colours 2.5yr – 4/6 and 10r – 3/6), mainly consisting of angular pebbles in an abundant muddy-sandy matrix. this colluvial deposit is in turn covered by a more recent pedogenic flow debris (munsell colour 5yr – 4/6). carta. settore 2: dal torrente letimbro al torrente sansobbia il terrazzo, intagliato nel substrato metamorfico, si presenta suddiviso in sette lembi terrazzati la cui ampiezza è compresa tra 400 e 600 m. il margine interno varia da 65 a 70 m s.l.m., mentre l'orlo esterno oscilla tra 45 e 55 m s.l.m. l'area è intensamente urbanizzata e non ha pertanto permesso di riconoscere bene gli eventuali depositi marini; la copertura, quando visibile, ha carattere continentale; nel deposito sono spesso presenti anche ciottoli arrotondati. settore 3: dal torrente sansobbia al torrente teiro-punta della mola il terrazzo risulta smembrato in numerosi lembi che si presentano piuttosto rimodellati ad esclusione di quello in località rio natta (tra celle e varazze); in questo settore sono compresi anche le tre superfici immediatamente ad est del torrente teiro. il terrazzo è intagliato nei conglomerati oligocenici (fig. 1) ed ha un margine interno che varia da so a ne da un minimo di 65 m ad un massimo di 80 m s.l.m. e l'orlo esterno che varia prevalentemente da 45 a 60 m s.l.m.su una distanza di 6 km. l’ampiezza del terrazzo (distanza tra l'orlo esterno ed il margine interno) raggiunge al massimo 750 m circa. i depositi sono scarsi e si ritrovano solo sui lembi meglio conservati: sono rappresentati da sabbie e ghiaie alterate. in particolare è descritto il deposito marino affiorante presso il margine interno in località rio natta. in questa località è stata riconosciuta la successione di fig. 5; la stratigrafia è composta di quattro 60 carobene-firpo intervalli sabbioso-ghiaiosi. l'embriciatura dei ciottoli verso se e verso so testimonia una trasgressione sul substrato oligocenico ed il relativo deposito di spiaggia. la sequenza descritta presenta localmente al suo top un paleosuolo (fig.6) dello spessore di circa un metro, coperto a sua volta da detrito più recente con una pedogenesi meno accentuata. al margine interno la sequenza è coperta da un colluvium molto pedogenizzato (2.5 yr fino a 10 r) che può essere coperto da detrito più recente (fig.a in tav.i). settore 4: da punta della mola al torrente arrestra il terrazzo è intagliato in rocce metamorfiche (fig. 1), presenta una buona continuità laterale ed un'ampiezza massima di 750 m. la quota del margine interno s’innalza in quota verso ne da 95 a 105 m, mentre l'orlo esterno oscilla tra 55 e 85 m su una distanza di 3,5 km (fig.7). il deposito marino, non sempre ben visibile in tutti i lembi sia per l'erosione subìta sia per le coperture continentali, si presenta solitamente costituito da grossi clasti ben arrotondati con diametri fino a 50-100 cm, a volte appiattiti; il taglio autostradale permette di vedere bene il deposito in corrispondenza del margine interno (fig.2 in tav i). in località "schiappapria", parte so del settore, la presenza di un pozzo d'acqua e i dati relativi alle fondazioni dell'albergo "la vignetta" hanno permesso di dedurre la presenza, sul substrato roccioso, di 4-6 metri di ghiaie marine coperte da alcuni metri di sedimenti detritici continentali (fig. 8). il settore in esame presenta inoltre i relitti di due lembi di una superficie terrazzata più alta compresa tra i 110 e i 140 m s.l.m., non riportata in tav.i per le sue dimensioni troppo limitate. settore 5: dal torrente arrestra al torrente lerone sono presenti cinque lembi di un terrazzo intagliato in serpentiniti e calcescisti del gruppo di voltri; la loro ampiezza varia da 250 a 600 m; il margine interno si mantiene tra i 115-120 m e l'orlo esterno tra gli 85 e 100 m s.l.m. il deposito marino è sempre presente ed è costituito in prevalenza da ciottoli ben arrotondati e 61forme terrazzate relitte ... fig. 6 deposito del lembo terrazzato di natta (settore 3), con margine interno a 75 m s.l.m. in basso affiora il substrato (s) costituito da conglomerato oligocenico molto alterato. il sovrastante deposito marino (dm), che ha uno spessore di 1,5 m, si presenta pedogenizzato con colori 2.5yr 3/6 e 4/8; la sua stratigrafia corrisponde a quella rappresentata in fig.5. in alto il paleosuolo (p) ha spessore di 1 metro ed è inclinato di circa 2° verso sud; si presenta argilloso, con screziature grigio-azzurre (n6/) e rosse (4/6) comprese nella carta munsell 2.5yr. il paleosuolo è ricoperto da debris–flow molto arrossato (10yr 4/6) e da successive coperture detritiche meno pedogenizzate. deposit on the terrace of natta (sector 3) with inner margin 75 m above sea level. at the base there is a substratum (s) of very weathered oligocene conglomerate. the overlying marine deposit (dm), which is 1.5 m thick, is reddish with munsell colours 2.5yr 3/6 and 4/8. its stratigraphy corresponds to that represented in fig. 5. the paleosoil (p) on top has a thickness of 1 m and is dipped about 2° to the south; it is clayey, with blue-grey (munsell 2.5yr-n6/) and red (munsell 2.5yr4/6) variegation. the paleosoil is covered with very reddened (10yr4/6) debris flow and weathered successive detritic layers. fig. 7 panoramica della superficie terrazzata di punta d’invrea (settore 4) vista da ne. view of terraced remains at punta d’invrea (sector 4) from the ne. spesso appiattiti con diametri prevalenti fino a 20 cm; lo spessore rilevabile è di almeno 2 m mentre quello della copertura continentale è generalmente debole ed in particolare è scarso o assente il deposito di piede di versante. localmente il deposito si presenta alterato. settore 6: dal rio lerone al rio lupara il settore è caratterizzato dalla grande superficie pp ss dd mm terrazzata di arenzano (fig.9) priva di margine interno, che si estende lungo costa per 1,5 km, con ampiezza massima di circa 800 m. la superficie è intagliata in rocce metamorfiche (fig.1) con un'elevazione massima di 111 m; l'orlo esterno, verso mare, varia tra i 70 e i 90 m. l'area si presenta intensamente antropizzata ed urbanizzata rendendo difficile la descrizione del deposito terrazzato; esso è costituito da ciottoli arrotondati di grande diametro e sabbie alterate. a nord, al piede dei rilievi, si estendono dieci lembi relitti con ampiezza variabile da un minimo di 100 m ad un massimo di 300 m del lembo meglio conservato in località terrarossa. il margine interno di questi relitti varia da 115 a 130 m mentre l'orlo esterno varia tra 85 e 110 m s.l.m, su una distanza di 3,5 km. i depositi di piede di versante, costituiti da brecce grossolane in 62 carobene-firpo fig. 8 profilo della superficie terrazzata nel settore 4, lembo so. l’analisi delle carte topografiche evidenzia il margine interno (m.i.) del terrazzo e il suo orlo esterno (o.e.); essi delimitano la superficie terrazzata (s.t.), con inclinazione media di circa 8°. i dati di un sondaggio e la presenza di un pozzo per acqua (p) hanno permesso di riconoscere la presenza di un corpo sedimentario marino (c.s.m.) costituito da ghiaie, avente uno spessore massimo di circa 5 metri, che diminuisce progressivamente verso mare fino ad annullarsi. esso poggia su una piattaforma di erosione marina (p.e.m.), delimitata da un margine interno (m.i.p.) e da un orlo esterno della piattaforma (o.e.p.) ottenuti mediante ricostruzione geometrica; la piattaforma ha una inclinazione di circa 2,8°. la superficie terrazzata è delimitata da due scarpate (s.): quella a monte ha un’inclinazione di 22°, quella a valle di 26°. il terrazzo è intagliato in un substrato oligocenico (s.o.) costituito prevalentemente da conglomerati. il deposito marino è ricoperto da detrito continentale (d.c.) costituito da colluvium e debris flow. profile of the terraced surface in sector 4, sw remains. the analysis of the topographic chart reveals the inner margin (m.i.) of the terrace and its outer edge (o.e.); these delimit the terraced surface (s.t.), with a mean inclination of 8°. the survey data and the presence of a well (p) enabled us to recognise a marine sedimentary body (c.s.m.) consisting of a layer of gravel with a maximum thickness of about 5 m which progressively diminishes towards the sea until it disappears. this lies on a marine erosion platform (p.e.m.) delimited by an inner platform margin (m.i.p.) and an outer platform edge (o.e.p.) determined by geometric reconstruction. the platform has an angle of inclination of 2.8°. the terraced surface is delimited by two slopes (s): the landward one has an angle of inclination of 22°, the seaward one 26°. the surface is cut by an oligocene substratum (s.o.) consisting mainly of conglomerates. the marine deposit is covered by continental detritus (d.c.) consisting of colluvium and flow debris. fig. 9 veduta del terrazzo di arenzano (settore 6) da ovest. view of terraced surface at a r e n z a n o (sector 6) from the w. matrice limosa mascherano, con spessori di parecchi metri, il margine interno della superficie di abrasione che si situa, dove si è potuto vedere, a 115 m s.l.m. il deposito terrazzato è costituito da ciottoli arrotondati decimetrici coperti da depositi continentali a clasti spigolosi molto rubefatti (colore munsell 2.5 yr 3/6). il deposito è assente nei relitti più rimodellati costituiti da stretti crinali in roccia mentre è ancora ben conservato in località bicocca dove sul substrato metamorfico poggiano grossi ciottoli decimetrici tra cui evidenti quelli appiattiti. settore 7: dal rio lupara al torrente cerusa i calcescisti caratterizzano il substrato di questo settore (fig.1) e la loro forte erodibilità ha condizionato la conservazione dei terrazzi. lungo tutto il settore infatti sono difficilmente riconoscibili superfici terrazzate, ma sono presenti invece limitati crinali molto rimodellati o isolate culminazioni in gran parte non indicate nella tav.i, ad una quota compresa tra 115 e 135 m. le poche forme riconducibili a questo ordine di terrazzi conservano localmente ancora ciottoli arrotondati da centimetrici a decimetrici direttamente poggianti sul substrato metamorfico. settore 8: dal torrente cerusa al rio san pietro il substrato affiorante in questo settore è costituito da calcescisti, serpentinoscisti e metagabbri (fig.1); analogamente al settore precedente la natura litologica non ha favorito la conservazione dei terrazzi. inoltre l'intensa urbanizzazione, maggiore sulle superfici terrazzate, non ha permesso l'osservazione degli eventuali depositi. nel settore il lembo terrazzato maggiore è quello di località "castello" (villa galliera) alle spalle di voltri; esso è costituito da una piccola articolata superficie sommitale, priva quindi di margine interno, con quota massima a 112 m. il substrato è costituito da micascisti localmente coperti da biocalcareniti e sabbie limose stratificate, riferibili al pliocene in base al contenuto fossilifero (rovereto, 1939); substrato e depositi pliocenici sono stati spianati dal mare durante il modellamento del terrazzo. in tutto il settore non sono stati rinvenuti depositi riferibili al terrazzamento marino. altre testimonianze di quest'ordine sono culminazioni a quote simili, tra cui ricordiamo il bric bacciocco (124 m) che prosegue verso monte con un crinale suborizzontale avente margine interno alla quota di 135 m. settore 9: dal rio san pietro a multedo sono evidenti in questo settore le forme riferibili all'ordine in oggetto, il cui margine interno si situa tra 135 e 145 m e l'orlo esterno varia tra 115 e 120 m (fig.10). per le profonde modificazioni antropiche (vecchie postazioni militari) e per l'erodibilità del substrato (calcescisti e metagabbri) non è possibile riconoscere eventuali coperture terrazzate marine, eccetto quelle continentali a clasti spigolosi. l'analogia della forma e della quota permettono di attribuire anche questi relitti allo stesso ordine delle superfici terrazzate descritte precedentemente. b ) l' ordine di terrazzi a +65 m l'ordine a 65 m è osservabile tra il torrente leiro e multedo: si presenta con una serie di piccoli lembi terrazzati tra le quote di 60-65 m (margine interno) e 45 m (orlo esterno). la forte urbanizzazione e le coperture di piede di versante non hanno permesso osservazioni sui depositi marini eventualmente presenti, ad eccezione del cimitero di pegli e dei giardini di villa doria (fig. 10) dove sono visibili, al di sopra del substrato metamorfico (calcescisti), alcuni metri di deposito ciottoloso fino alla quota di 50-55 m. i ciottoli sono ben arrotondati con diametri di 5-15 cm; il deposito è fortemente pedogenizzato (2.5yr 4/8 3/6) e verso monte è coperto da detriti spigolosi di piede di versante. il salto morfologico con la paleofalesia a monte è sempre netto. questo ordine non è stato ritrovato (a questa quota) nel tratto a so di voltri. 44..33.. ii tteerrrraazzzzii bbaassssii l'ordine a +17 metri lungo l'arco di costa studiato compaiono saltuariamente terrazzi e depositi ben individuabili, con margine interno alla quota costante di 25 m. queste terrazzi possono corrispondere, come già detto, a due piattaforme marine con margini interni a 17 e 7 metri s.l.m. (fig. 11). quest'ordine è già stato descritto in località voltri ( settore 8 ) (carobene & firpo, 1994) dove depositi di spiaggia per uno spessore di 5 m ricoprono una piattaforma d'abrasione in roccia inclinata verso mare di 1,6°; ghiaie di battigia sono state riconosciute fino alla quota di 17 m (fig.4 in tav.i). una 63forme terrazzate relitte ... fig. 10 profilo topografico del crinale a n di pegli (settore 9), che mostra le superfici terrazzate con margine interno a 145 m e a 55 m s.l.m. la ricostruzione geometrica (in alto) del profilo topografico evidenzia le inclinazioni dei vari segmenti del profilo. s = scarpate; t = terrazzi. topographic profile of the ridge in the northern part of pegli (sector 9), that shows the terraced surfaces with inner margin at 145 m and 55 m above mean sea level. the geometrical reconstruction (top) of the topographic profile highlights the angle of inclination of the various segments of the profile. s = slope; t = terrace. situazione analoga è stata riscontrata nell’abitato di cogoleto (settore 5), dove un deposito di ghiaie embriciate di spiaggia è esteso fino alla quota di 15,6 m all'interno di un solco d'erosione marina in dolomie triassiche (fig. c in tav i). a capo torre, in destra del rio carrea (settore 3), una superficie di erosione marina tagliata nel conglomerato oligocenico conserva un relitto di sabbie medie, ben selezionate, senza ciottoli, per uno spessore di circa 1 metro. le sabbie, che si elevano fino alla quota di circa 18 m, risultano pedogenizzate (colore munsell 7.5 yr-4/6) e coperte da detrito colluviale (colore munsell 10 yr4/3). un'altra spianata simile a quella di voltri si rinviene a pegli in piazza bonavino, dove tuttavia non si è potuta osservare la stratigrafia dell’eventuale deposito. inoltre a celle in località rio natta (settore 3) (fig b in tav.i) è attribuibile a questa linea di riva un deposito di sabbia e ghiaia esteso tra i 12 e i 14 m. dalle osservazioni effettuate si può dedurre che la quota di quest'antica linea di riva rimane costante in tutto il tratto di costa studiato. l' ordine a +7 metri anche questo ordine di terrazzi è già stato descritto a voltri (settore 8) (carobene & firpo, 1994) dove i sondaggi hanno messo in evidenza una piattaforma di abrasione con margine interno a circa 7 m s.l.m. e inclinazione pari a 1,6°, coperta sia da sabbie e ciottoli arrotondati che da depositi detritici continentali a clasti spigolosi. conferme di questa linea di riva sono state riscontrate tra il torrente arrestra e il rio arenon (settore 4) al termine del lungomare europa, dove è visibile una superficie di erosione in substrato metamorfico con inclinazione verso mare di 1,5° ricoperta nella parte più a monte da un deposito marino ciottoloso con spessore massimo di 130 cm, sormontato a sua volta da un deposito continentale a clasti spigolosi di piede di versante di circa 9 m di spessore. inoltre nella parte ad est di cogoleto (settore 5) ricordiamo il lembo citato già da issel nel 1883 in località "lo scoglio". il nostro rilevamento (fig. d in tav. i) ha messo in evidenza un deposito sabbioso-ciottoloso di spiaggia poggiante su una superficie di abrasione a circa 4 m s.l.m. per uno spessore di quasi 1,5 m, che si estende verso monte fino alla quota massima osservata di 6 m. recenti scavi lungo la strada s.s.aurelia (ad e di cogoleto) hanno permesso di osservare che il deposito ciottoloso ricopre, con uno spessore di circa 1,5 m, una piattaforma di abrasione che risale dolcemente da 5 a 6 m s.l.m; il deposito marino è coperto da un potente deposito continentale alterato e arrossato esteso fino alla quota di 14-15 m. (vedi fig.11). lungo la strada costiera infine gli scavi hanno evidenziato il substrato metamorfico alla quota di 3,5 m coperto da ciottoli decimetrici arrotondati alterati; l'osservazione puntuale non ha permesso di ricavare la quota del margine interno. analogamente alla precedente, anche in questo caso la linea di riva sembra mantenere la stessa quota di circa 7 m lungo tutta l'area indagata. 55.. ccoonncclluussiioonnii le ricerche sui terrazzamenti di origine marina, condotte lungo il tratto di costa tra genova e savona fino alla quota di 400 m, hanno permesso di: 1 )definire varie tipologie di forme terrazzate relitte (tav.i); la varietà delle forme è in funzione del diverso grado di erodibilità del substrato, della estensione originaria del terrazzo e delle differenti età dei terrazzi. 2) riconoscere con certezza due ordini di superfici terrazzate, tra le tante riconosciute e mappate in tav.i. l’ordine più evidente è quello a 60÷145 m che appare basculato (vedi avanti al punto 5). a quota più bassa risulta ben delineato l’ordine con margine interno a 25 m (settori 5 e 8); ad esso possono corrispondere due differenti piattaforme di erosione marina (fig. 11) e quindi due antiche linee di riva poste a 7 e a 17 m s.l.m. (paragr.4.3.). localmente, in particolare tra cogoleto e varazze, la piattaforma marina a +7 m appare distinta da quella più alta ed è documentata da depositi marini. queste due linee di riva sembrano avere andamenti suborizzontali e si possono pertanto collegare agli alti eustatici più recenti, ovvero agli stages isotopici 9 oppure 11 per la linea a 17 m e allo stage 5e per la linea a 7 m, come già sostenuto da carobene & firpo (1994). 64 carobene-firpo fig. 11 schema della superficie terrazzata con margine interno a 25 m presente nei settori 5 e 8: st = superficie del terrazzo; pf.d. = paleofalesia degradata; c. = colluvium; d.c. = deposito continentale; m.i. = margine interno; o.e. = orlo esterno; p.m.i = piattaforma marina riferita agli stages 9 o 11; p.m.ii = piattaforma marina riferita allo stage 5; pf.s. = paleofalesia sepolta; m.i.p.= margine interno delle piattaforme marine; d.m.= deposito marino; l.m.= livello mare attuale. scheme of the terraced surfaces with an inner margin at 25 m above s.l. in sectors 5 and 8: st = terrace surface; pf.d = degraded paleocliff; c = colluvium; d.c. = continental deposit; m.i. = inner margin; o.e. = outer edge; p.m.i = marine platform associated with ois 9 or 11; p.m.ii = marine platform associated with ois 5e; pf.s. = buried paleocliff; m.i.p. = inner margin of marine platform; d.m. marine deposit; l.m. = actual sea level. meno rappresentato appare un ordine intermedio, corrispondente alle superfici con margine interno a 60-65 m presenti nel settore 9; queste sono state correlate con le superfici aventi margine interno a 35 m del settore 1. 3) evidenziare numerosi relitti di superfici terrazzate, più alte degli ordini precedenti, che risultano difficilmente correlabili tra loro in quanto fortemente rimodellate, discontinue e prive di depositi. 4) riconoscere e documentare litofacies, spessori e grado di pedogenesi delle coperture sedimentarie dei terrazzi, sia marine che continentali. in particolare l’origine marina degli ordini più bassi è documentata, oltre che dagli aspetti morfologici delle singole superfici terrazzate, anche dalle caratteristiche sedimentologiche dei depositi ritrovati nel corso della presente ricerca (cap.3); lo studio dei terrazzi fluviali (ricerca ancora in corso) sembra confermare inoltre l’origine marina anche per alcuni ordini terrazzati alti, come hanno evidenziato le ricerche sulla val varenna (brancucci & marini, 1990), dove sono stati riconosciuti terrazzi fluviali alti che si raccordano con spianate a 200-250 m s.l.m. 5) accertare un basculamento per l’ordine terrazzato a 60÷145 m, che risulta più sollevato a genova (tav.i). le possibili correlazioni tra le varie superfici sono state evidenziate dalla proiezione su un piano verticale circa ne-so per i settori da 1 a 7 e circa e-o per i settori 8 e 9, di tutte le quote dei margini interni delle forme terrazzate e di tutte le quote della più alta culminazione presente lungo i crinali privi di margine interno (fig. 12). in tal modo appare evidentissima la correlazione tra le superfici rappresentate in arancione in tav.i ed il basculamento subìto dall’antica linea di riva. per l’ordine immediatamente più basso il basculamento è stato supposto, correlando le quote di 35 m a so (settore 1) con quelle a 65 m a ne (settore 9). per i terrazzi più alti il basculamento è di difficile riconoscimento a causa dell’eccessiva frammentazione erosionale; una possibile correlazione è stata tracciata solamente per l’ordine di superfici comprendenti il grande terrazzo di prato zanino. 6) una suddivisione del tratto di costa in settori (fig.2), diversi tra loro per gli aspetti morfologici e litologici, ma anche per la diversità di quote che presentano gli ordini terrazzati (fig. 12). analizzando il progressivo aumento delle quote del terrazzo a 60÷145 m (da savona a genova-pegli), si può notare un’altra particolarità dei settori: la quota sale regolarmente da 65 a 80 m nel tratto corrispondente ai settori 1, 2 e 3; al passaggio tra i settori 3 e 4 la quota subisce uno scatto improvviso di circa 15 m, da 80 a 95 m; analogamente, al passaggio tra i settori 4 e 5, la quota sale da 105 a 120 m, con uno scatto di altri 15 m circa; nei settori 5 e 6 la quota rimane quasi costante, sui 120-125 metri; nei settori 7, 8 e 9, infine, le superfici terrazzate risultano comprese tra 135 e 150 metri. pertanto si può concludere che nel basculamento generale che porta le quote dei margini interni dei lembi relitti del terrazzo a salire dai 65 m (di savona) ai 145 m (di genova-pegli), vi sono incrementi di quota imputabili a faglie ad attività recente, trasversali alla costa; di particolare importanza le due linee tettoniche che limitano il settore 4, corrispondenti probabilmente ai tratti con andamento rettilineo dei torrenti teiro ed arrestra. i dati raccolti hanno permesso inoltre di: 7) riconoscere due fasi di sollevamento, manifestatesi nel tempo con differenti velocità. 8) stabilire limiti di età dei terrazzi che, comunque, rimangono da confermare con dati radiometrici, geochimici o paleontologici. per quanto riguarda i punti 7 e 8 sopra enunciati, relativi al sollevamento e all’età dei terrazzi, in assenza di datazioni di qualunque natura si è dovuto procedere mediante un ragionamento basato: a) sulla presenza di alcuni dati certi; b) sulla formulazione di alcune ipotesi; c)sulla conseguente deduzione di eventi e processi; d)sulla conferma più o meno esaustiva di quanto dedotto, mediante prove o evidenze di terreno. aa)) ii ddaattii il pliocene inferiore è il termine più recente del substrato nel tratto da genova a savona; non è documentata la presenza in affioramento di depositi marini del pliocene medio e superiore (late pliocene) (boni et al., 1981). il pliocene inferiore, in facies prevalentemente argilloso-marnosa, è conservato (tra savona e genova) in lembi sparsi a quote inferiori ai 100 metri (rovereto, 1934; boni & peloso, 1973; fanucci & tedeschi, 1983). fa eccezione il lembo di sciarborasca, innalzato per faglie a circa 200 m. i terrazzi alti (più alti dell’ordine a 60÷145 m) sono molto erosi e senza depositi , discontinui e difficilmente correlabili. il terrazzo attualmente costituito dalle superfici con margine interno variabile tra 60 e 145 m (da savona a genova) si forma dopo l’emersione del pliocene inferiore, in quanto le superfici terrazzate tagliano i depositi pliocenici ove affioranti ( savona, albissola, varazze, arenzano, voltri, genova-borzoli). i terrazzi intermedi e bassi (a partire dall’ordine a 60÷145 m) hanno superfici meglio conservate, sulle quali è quasi sempre possibile osservare depositi sia marini che continentali. bb)) llee iippootteessii per arrivare a quantificare i tassi di sollevamento e le età dei terrazzi, i dati sopra citati non sono sufficienti, ma permettono di formulare alcune ipotesi. occorre premettere che nel pliocene inferiore il margine continentale subisce veloce sommersione, sia per cause eustatiche che tettoniche; ciò determina la deposizione di argille la cui batimetria è variabile nei vari affioramenti, ma sempre riferibile al piano batiale, con profondità fino a 600 m ed oltre (negri et al., 1997); la sedimentazione comprende alternanze di conglomerati e argille (boni et al., 1985; gnaccolini, 1998) riferibili a deltaconoidi (marini, 2001), che documentano una progressiva inversione di tendenza dei movimenti verticali: l’emersione fu probabilmente molto rapida, tanto che non sembra documentabile in liguria il pliocene medio e superiore (late pliocene) lungo la costa emersa in esame (boni et al., 1981). premesso ciò, le ipotesi utilizzate sono le seguenti: il sollevamento dei depositi del pliocene inferiore si può far iniziare circa 4 milioni di anni fa (1° fase di sollevamento). il sollevamento porterà all’emersione del pliocene inferiore. l’emersione dei depositi del pliocene inferiore avviene durante il pliocene stesso. la batimetria del pliocene inferiore in facies argillosa è variabile, ma mediamente pari a 400 metri. 65forme terrazzate relitte ... cc)) llee ddeedduuzziioonnii la durata della 1° fase di sollevamento è uguale o minore di 2 milioni di anni. dopo l’emersione, il pliocene inferiore subisce un secondo sollevamento fino a 100 m s.l.m. attuale (fino a 200 m per faglia) (2° fase di sollevamento). la durata della 2° fase di sollevamento è uguale o maggiore di 2 milioni di anni. il tasso di sollevamento nella 2° fase di sollevamento è di conseguenza almeno 4 volte minore che nella 1°. il sollevamento e il basculamento dell’ordine di terrazzi oggi a 60÷145 m avviene durante la 2° fase di sollevamento. dd)) llee pprroovvee le due distinte fasi di sollevamento sono testimoniate da due differenti aspetti morfologici del versante costiero ligure: una fascia costiera superiore, compresa tra 100 e 400 m circa di quota (limite della zona indagata), larga mediamente 2 km (fino a 5 km nell’area albissola-varazze), prodotta da un sollevamento abbastanza veloce e molto antico. l’altro aspetto è costituito dalla fascia costiera inferiore, estesa al di sotto dei 100150 m; essa è larga mediamente 750 m e comprende l’ordine terrazzato a 60÷145 m. questa fascia testimonia la 2° fase del sollevamento, che si è manifestato len66 carobene-firpo fig. 12 proiezione su un piano verticale circa so-ne, da savona a genova, di tutte le quote dei margini interni delle superfici terrazzate e della quota più alta delle culminazioni presenti lungo crinali suborizzontali (dalla tav.i). è riportata in ascisse la suddivisione in 9 settori (fig.2) e la suddivisione altimetrica delle forme terrazzate relitte in una fascia inferiore (fi.) comprendente i terrazzi meglio conservati (probabilmente di età quaternaria) e in una fascia superiore (fs.) comprendente tutti i relitti terrazzati più erosi (probabilmente di età pliocenica). la fascia fi. comprende l’ordine meglio correlato 60÷145 m tra cui la grande superficie terrazzata di arenzano (indicata con la lettera a); il terrazzo si alza progressivamente in quota verso genova a causa di un basculamento in parte imputabile a faglie ad attività recente. questo andamento permette di correlare anche i terrazzi a 35 m dell’area di savona con quelli a 60-70 m presenti nel settore 9, ed inoltre di tentare la probabile correlazione della grande superficie di prato zanino (pz) con altri ampi crinali posti tra 110 m (settore 2) e 236 m (settore 7). nella fascia superiore (fs.) è stata infine circoscritta l’area s che comprende i relitti di terrazzi con quote da 261 e 290 m. vertical projection plane, approximately sw – ne, of the coast between savona and genoa, showing the elevations of the inner margins of all the terraced surfaces and the highest elevation of the culminations along the subhorizontal ridges (from table i). the subdivision into 9 sectors (fig. 2) and the altimetric subdivision of the relict terraced landforms into a lower band (fi), which includes the better preserved terraces (probably quaternary in age), and an upper band (fs), which includes all the more eroded terraced relics (probably pliocene in age), are presented in abscissa. the lower band includes the best correlated order, lying between 60 m at savona and 145 m above s.l. at genoa, which incorporates the large terraced surface of arenzano (indicated by the letter a); the terrace progressively rises towards genoa due to tilting, which can be partly attributed to faults and recent activity. this trend permitted us to correlate the large surface of prato zanino (indicated by the letters pz) with other wide ridges lying between 110 m (sector 2) and 236 m above s.l. (sector 7). the upper band includes area s, which incorporates terraced relics with an elevation between 261 and 290 m above s.l. tamente fino ai nostri giorni (fig. 12). il sollevamento (pliocenico e abbastanza veloce) che ha prodotto la fascia costiera superiore è documentato da numerosi relitti di superfici terrazzate, molto rimodellati, che si presentano come stretti crinali suborizzontali e come culminazioni a quote ricorrenti; è immaginabile che molte superfici terrazzate siano state completamente distrutte. il lento sollevamento che ha prodotto invece la fascia costiera inferiore trova conferma nella bassa quota del terrazzo a 60÷145 m, ampiamente inciso dai corsi d’acqua che lo hanno suddiviso originando decine di superfici terrazzate (circa 65), allungate lungo i crinali che scendono verso mare. poiché è il primo terrazzo che si è formato dopo l’emersione del pliocene inferiore, la sua età è antica,come viene documentato al punto seguente, e il suo sollevamento è essenzialmente quaternario. l’età antica del terrazzo a 60÷145 m è testimoniata dal sensibile rimodellamento delle superfici terrazzate, dalla parziale o totale erosione dei depositi terrazzati e dalla forte pedogenesi che essi presentano; considerazioni sul profilo pedologico permettono di affermare che nella maggior parte dei casi è presente solamente la parte basale dell’orizzonte b, con conservazione dei ciottoli originari, anche se molto alterati, caratterizzati da concentrazioni o spalmature nerastre di ossidi di fe e mn, accumulo di argille e forte rubefazione (colori munsell prevalenti 2,5 yr, fino a 10 r). anche il forte basculamento già descritto confermerebbe l’età antica di questo origine di terrazzi che, pertanto, può essere posta tra la fine del pliocene e il pleistocene inferiore. anche il lento sollevamento quaternario sembra documentabile; infatti tra l’ordine dei terrazzi a 60÷145 m e l’attuale linea di costa si contano solamente due ordini intermedi: quello a 60-65 metri del settore 9 (correlato con quello a 35 m del settore 1), e il terrazzo a 25 m dei settori 5 e 8. inoltre la morfologia costiera è caratterizzata da versanti ripidi o da falesie tra i principali corsi d’acqua. queste caratteristiche si ritrovano lungo altre coste della penisola italiana che durante il quaternario hanno subìto un lento sollevamento (vedasi carta neotettonica d’italia), quali ad esempio le coste di campania, basilicata, puglia e sardegna. in tale carta la fascia costiera della liguria di ponente è rappresentata in “standstill or moderate uplift in quaternary” (c.n.r., 1987). d’altra parte le coste a forte sollevamento quaternario si presentano tipicamente terrazzate (bosi et al., 1996), con 5-10 ordini di terrazzi ben evidenti; in lucania (amato et alii, 1998, calabria (barrier et alii, 1986; carobene & ferrini, 1993; ghisetti, 1981; miyauchi et alii, 1994) e sicilia (carbone et alii, 1983; di grande & raimondo, 1984), dove i tassi di sollevamento quaternario hanno valori di 0,5-1 mm/a, i terrazzi del pleistocene inferiore e medio si ritrovano ben conservati a parecchie centinaia di metri di altezza. le quote delle due linee di riva più basse (a +7 e a +17 m) attribuite rispettivamente allo stage 5 e agli stages 9 o11 (carobene & firpo, 1994), denunciano tassi di sollevamento inferiori o uguali a 0,05 mm/a; ciò sembra indicare che il tasso di sollevamento quaternario è andato diminuendo nel tempo. riassumendo le considerazioni sulle età e sui sollevamenti plioquaternari dei terrazzi evidenziati nel tratto di costa tra savona e genova, è possibile affermare che il versante costiero è caratterizzato da: 1) una fascia superiore estesa tra 100 e 400 m circa che comprende terrazzi sollevatisi durante il pliocene medio-superiore (1° fase di sollevamento, abbastanza veloce); 2) una fascia inferiore estesa dal livello del mare fino a 100-150 m circa comprendente terrazzi sollevatisi essenzialmente nel quaternario (2° fase di sollevamento, piuttosto lento). considerata la grande differenza di conservazione tra i terrazzi delle due fasce e la diversa distribuzione e numero delle superfici che le caratterizzano, sembra possibile avanzare l’ipotesi che le due fasce siano divise da un evidente intervallo cronologico. un’altra particolarità (alla quale si era già accennato al paragr. 2.1.) è il sostanziale andamento rettilineo della costa tra savona e voltri (retta tangente: savonapunta celle-punta dell’olmo-punta d’invrea-arenzanoscoglio nave). ciò può essere imputato ad un limite per faglia tra la zona costiera sollevatasi nel corso del plio-quaternario e la zona di piattaforma attuale subsidente. del resto faglie parallele alla costa sono già state segnalate in piattaforma (fanucci & nosengo, 1979; c.n.r., 1987). rriinnggrraazziiaammeennttii gli autori vogliono ringraziare il prof. tiziano mannoni per i dati forniti; il dott. m. marini per le utili discussioni ed il dott. c. queirolo per il contributo fornito nell’informatizzazione dell’iconografia. si ringraziano inoltre il prof. f. carraro per la revisione critica del manoscritto ed un anonimo revisore per gli utili suggerimenti. ricerche condotte con i fondi ateneo 1997-98 (020301001048) e 2000 (020301001088) riguardanti aspetti di geologia del quaternario in liguria; responsabile luigi carobene. llaavvoorrii cciittaattii amato a., belluomini g., cinque a., manolio m. & ravera f. (1998) terrazzi marini e sollevamenti tettonici quaternari lungo il margine ionico dell’appennino lucano. il quaternario, 1100(2), 1997, 329-336. barrier p., di geronimo i. & lanzafame g. (1986) i rapporti tra tettonica e sedimentazione nell’evoluzione recente dell’aspromonte occidentale (calabria). riv. it. paleont. strat., 9911(4), 537-556. boni p. & peloso g.f. (1973) i lembi pliocenici della liguria occidentale da terzorio al confine italofrancese. atti ist. geol. univ. pavia, 2233, 170-201. boni a., boni p., peloso g.f. & gervasoni s. (1985) nuove osservazioni e considerazioni sui lembi pliocenici del confine di stato a capo sant’ampelio. atti ist. geol. univ. pavia, 3300 (2), 246-309. bosi c., carobene l. & sposato a. (1996) il ruolo dell’eustatismo nella evoluzione geologica nell’area mediterranea. mem. soc. geol. it., 5511, 363-282. brancucci g. & marini m. (1990) stadi evolutivi della val varenna (riviera di ponente, liguria). boll. 67forme terrazzate relitte ... soc. geol. it., 110099, 351-365. c.n.r. (1987) neotectonic map of italy. quaderni della ricerca scientifica, 44, n.114, 6 tavv. 1:500.000. carbone s., di geronimo i., grasso m., iozzia s. & lentini f. (1983) i terrazzi marini quaternari dell’area iblea (sicilia sud-orientale). c.n.r. prog.final.geodin., 550066 (1982), 1-35, napoli. carobene l. & ferrini g. (1993) morphological, sedimentological and tectonic features of diamantem.carpinoso marine terrace flight (tyrrhenian coast of northern calabria, italy). earth surf. proc. and landforms, 1188,, 225-239. carobene l. & firpo m. (1994) una paleospiaggia tra voltri e palmaro (genova): evidenze sedimentologiche e morfologiche. il quaternario, 77 (1), 123138. cortellesi d., fanucci f., giuffrè a., tedeschi a. & vignolo a. (1979) dati preliminari sulla neo-tettonica del foglio 82 genova . c.n.r.prog.final.geodin., 225511, 579-595, napoli. cortemiglia g.c. (1983) indizi geomorfologici significativi quale contributo alla stesura di una carta neotettonica della liguria. prog.final.geodim., 551133 (ii) (1982),397-404, napoli. di grande a. & raimondo w. (1984) linee di costa plio-pleistoceniche e schema litostratigrafico del quaternario siracusano. geologica rom., 2211 (1982), 279-309. fanucci f. & nosengo s. (1979) rapporti tra neotettonica e fenomeni morfogenetici del versante marittimo dell’appennino ligure e del margine continentale. boll. soc. geol. it., 9966 (1977), 41-51. fanucci f. & tedeschi d. (1983) linee di costa e terrazzi marini del foglio 82 (genova). c.n.r. prog.final.geodin., 551133 (ii) (1982), 387-396, napoli. fanucci f. (1976) il plioquaternario della piattaforma continentale ligure tra genova e savona. atti del ii congr. naz. a.i.o.l., santa margherita ligure; 8187. fanucci f. (1987) lignes de rivage quaternaires sur la côte et le plateau continentale ligure. z. geomorph. n. f., 3311 (4), 463-472. ghisetti f. (1981) caratterizzazione dei blocchi della calabria meridionale in base alle velocità di sollevamento nel plio-pleistocene: una proposta di zonazione neotettonica. c.n.r. prog. final. geodin., 335566 (ii) (1980), 775-809, napoli. gnaccolini m. (1998) le successioni conglomeratiche plioceniche della liguria occidentale: osservazioni preliminari sulla loro architettura e relativo significato. atti tic. sc. terra, 4400, 203-214. issel a. (1883) antiche linee litorali della liguria. boll. soc. geol. it., 11 (1882), 222-232. issel a. (1911) l’evoluzione delle rive marine in liguria. boll. soc. geogr. it., fasc. 9-12, 112 pp., roma. limoncelli. b. & marini.m. (1969) indagine sulle risorse paesaggistiche e sulle aree verdi della fascia costiera ligure. ist. archit. tecn. urban. fac. ingen.univ. genova c.n.r.,115 pp, 5 tav., scuola graf. don bosco genova. marini m. (2001) il pliocene ligure fra ventimiglia e bordighera (imperia, alpi marittime liguri): osservazioni preliminari. boll. soc. geol. it., 112200 (2001), 37-46. miyauchi t., dai pra g. & sylos labini s. (1994) geochronology of pleistocene marine terraces in the tyrrhenian coast of south calabria, italy. il quaternario, 77 (1/a), 17-34. negri a., pirini c., razzore s., bonci m.c. (1997) micropaleontological record in the pliocene of genoa-arenzano area. boll. soc. paleont. it., 3366 (1-2), 261-274. rovereto g. (1934) epirogenesi postpliocenica delle alpi marittime e della riviera ligure. rend. acc. naz. lincei, serie 6, 2200 (5-6), 153-157, roma. rovereto g. (1939) liguria geologica. mem. soc. geol. it., 22, 1-743. s.g.i. (1991) alpi liguri. guide geologiche regionali, 295 pp., be-ma ed. s.g.n. (1994) carta geomorfologica d’italia 1:50.000 guida al rilevamento. quad. s.iii, 44, 42 pp., ist.pol.zecca stato, roma 68 ms. ricevuto il 3 gennaio 2002 testo definitivo ricevuto il 26 marzo 2002. ms. received: genuary 3, 2002 final text received: march 26, 2002 carobene-firpo impaginato carrara eelleemmeennttii ggeeoollooggiiccii ssuullllaa nneeccrrooppoollii eenneeoolliittiiccaa ddeellllaa sseellvviicccciioollaa ((iisscchhiiaa ddii ccaassttrroo - vviitteerrbboo)) ccllaauuddiioo ccaarrrraarraa11,, eeuuggeenniioo cceerriillllii22 && vvllaaddiimmiirroo vveerrrruubbbbii33 1via c. balbo, 35 00184 roma; 2soc. coop. arx, via s. giovanni in laterano 210, 00184 roma; 3enea-c.r. casaccia, via anguillarese 301, 00060 roma riassunto la necropoli eneolitica della selvicciola (metà del iv millennio fine del iii millenio a.c.) è situata a circa 7 km a so di ischia di castro (viterbo) sulla sponda sinistra del fosso strozzavolpe. lo studio dell'area, ancora in corso, è finalizzato alla definizione delle caratteristiche geo-morfologiche dell'ambiente del sito al momento dell'instaurarsi della necropoli e dell'interazione tra l'attività sorgentizia presente nell'area e quella antropica. le tombe della necropoli sono state scavate al di sotto di una copertura di travertino, che funge da tetto, facente parte dell'estesa placca travertinosa di monte doganella-monte canino, di età compresa tra il pleistocene medio e l'olocene, e localmente ancora in via di deposizione.il substrato vulcanico pleistocenico che ospita le tombe è fortemente pedogenizzato ed interessato da una superficie di erosione areale datata tra il pleistocene superiore e l'olocene, presente in tutta l'area. lo studio della stratigrafia del sito ha permesso di identificare livelli di limi calcarei organici contenuti nella parte basale del travertino che copre le tombe, mentre nella porzione superiore, interessata da cavità carsiche, è presente un suolo organico bruno-nerastro. la datazione radiocarbonio di detti livelli (rispettivamente cal bp 13180-11860 e cal bp 2956-2774) suggerisce che il travertino, nel sito, ha iniziato a deporsi verso la fine del tardiglaciale, prima dell'instaurarsi della necropoli, per proseguire fino al tardo olocene a necropoli abbandonata. sulla base dello studio di facies del travertino si può desumere che l'ambiente di deposizione all'inizio fosse fluviale fino a palustre con piccoli laghi e pozze. durante la frequentazione della necropoli doveva essere caratterizzato dalla presenza di sorgenti ancora attive, con locali pozze ed acque correnti canalizzate, probabilmente utilizzate e controllate dall'uomo, come è stato osservato in altre località vicine. i banchi più superficiali del travertino sono interessati da fenomeni carsici, connessi sia a una fase erosiva lineare molto intensa che ha approfondito notevolmente la rete idrografica e ha dissecato la copertura di travertino e il substrato vulcanico, sia a processi pedogenetici che hanno dato luogo al suolo bruno organico. abstract geological elements on the eneolitic necropoli of selvicciola (ischia di castro viterbo). the eneolitic necropoli of selvicciola (middle of the iv millenium end of the iii millenium a.c.) is located at about 7 km sw ischia di castro (viterbo) on the left side of fosso strozzavolpe. the study of the area, still continuing, is aimed at the definition of geo-morphological features of the environment at the time of establishment of the necropoli and of interaction between thermal springs present in the area and anthropogenic activity. the tombs of the necropoli have been dug under a travertine cover, that acted as a roof, and is part of the very extensive travertine plate of canino, of an age ranging between middle pleistocene and holocene and in places still precipitating. the pleistocene volcanic substrate containing the tombs is strongly pedogenized and cut by an irregular erosion surface, occurring in the whole area of canino, dated between upper pleistocene and holocene. the study of stratigraphic sections allowed the recognition of calcareous organic silty levels in the basal part of the travertine cover, whereas in the uppermost portion, affected by karstic cavities, a blackish-brown organic soil occurs. radiocarbon datings of the above-mentioned organic levels and soil (respectively cal bp 13180-11860 and cal bp 2956-2774) suggest that the travertine began to deposit towards the end of lateglacial, before the establishment of the necropoli, and carried on until the late holocene, until its abandonment. the facies analysis of travertine suggests that at the beginning the deposition environment could be fluvial to paludal. during the attendance of the necropoli the environment could be characterized by the occurrence of still active isolated springs, forming small running water resurgences and pools, likely utilized and controlled by human activity, as in other adjoining localities has been observed. the uppermost layers of the travertine cover, moreover, are affected by karstification, connected to a new erosion phase that caused the watertable lowering, the strong deepening of the hydrographic network and the dissection of the travertine cover and the substrate, as well as to pedogenetic processes that gave rise to the brown organic soil. parole chiave: archeologia, stratigrafia, travertino, ambiente di deposizione, pleistocene superiore, olocene, italia centrale. keywords: archeology, stratigraphy, travertine, deposition environment, upper pleistocene, holocene, central italy il quaternario italian journal of quaternary sciences 1155(2), 2002, 221-227 iinnttrroodduuzziioonnee la presente nota vuole illustrare i risultati preliminari di una ricerca geo-archeologica sul sito "la selvicciola" di ischia di castro (viterbo) iniziata alcuni anni or sono e ancora in corso, finalizzata alla definizione delle caratteristiche dell'ambiente geomorfologico e geologico nell'olocene, che ha visto l'instaurarsi e la frequentazione della necropoli eneolitica, nonché degli insediamenti di età romana e più recenti, parzialmente sovrapposti alla stessa. in particolare si é cercato di determinare, anche cronologicamente, i rapporti tra la deposizione del travertino che copre e in parte ingloba le tombe della necropoli, e l'interazione tra attività sorgentizia ed attività antropica. lo studio è stato condotto da ricercatori dell'enea in stretta collaborazione con archeologi della soprintendenza archeologica per l'etruria meridionale ed archeologi e geologi della società cooperativa arx. il presente lavoro è stato pubblicato con il sussidio dell'enea e dell'istituto di ricerche sulla tettonica recente del cnr. 222 c. carrara, e. cerilli & v. verrubbi iinnqquuaaddrraammeennttoo ggeeoollooggiiccoo il sito archeologico della selvicciola è ubicato 7 km circa a so di ischia di castro e 1 km circa a sse di località colle vepre, sulla sponda sinistra del fosso strozzavolpe, affluente del fiume fiora (foglio topografico 1:100.000, n. 136, tuscania; a cavallo delle tavolette 1:25.000, iv se, ponte s. pietro, e iii ne, riminino). il sito è compreso nell'area più settentrionale di una estesa placca di travertino (fig. 1), che si estende pressoché continua in direzione meridiana per circa 14 km e in direzione longitudinale per 6÷7 km ed è limitata a nord dal fosso strozzavolpe, ad est dal gruppo del monte canino, a sud dal fosso timone e ad ovest dal fiume fiora. la placca travertinosa affiora in parte al di sopra dei prodotti vulcanici dei monti vulsini di età pleistocenica, in parte su sedimenti mesocenozoici. la placca mostra una potenza variabile da pochi metri nelle parti periferiche fino a oltre 100 metri in località poggio olivastro, presso la dorsale monte doganella-monte canino, al cui sistema idrogeologico e strutturale è geneticamente connessa. la deposizione del travertino, infatti, è legata all'emergenza di acque termali ricche di sali di calcio e di anidride carbonica lungo le faglie a direzione appenninica ed antiappenninica, che limitano e suddividono in blocchi la suddetta dorsale (carrara, 1994). la parte più settentrionale della placca è limitata da una evidente scarpata morfologica alta alcuni metri sulla piana antistante, che in direzione grosso modo longitudinale corre da c.se riminino fino ai piedi di poggio olivastro. l'area è compresa tra le quote 120 e 270 m s.l.m. ed è caratterizzata da estesi espandimenti travertinosi a giacitura per lo più orizzontale, sovrapposti gli uni agli altri, e limitati da evidenti scarpate morfologiche. queste forme deposizionali tabulari, solcate da una rete idrografica molto incisa ed irregolare, drenante verso il fosso strozzavolpe e il fiume fiora, sono spesso costituite da più corpi travertinosi lobati, talora interdigitati, progradanti da nne verso sso. nell'area tra il fosso strozzavolpe e il monte fumaiolo si riconoscono, anche se rimodellati, i relativi coni sorgentizi, isolati o in gruppi allineati a formare veri e propri ridges fissurali, che presentano direzioni appenniniche (no-se) e circa-antiappenniniche (nne-sso). probabilmente ricalcano strutture tettoniche sepolte attraverso le quali le acque responsabili della deposizione del travertino raggiungevano la superficie. nel travertino sono diffuse anche forme carsiche tondeggianti che rappresentano inghiottitoi o sono connesse con crolli della volta di cavità e grotte. l'area del sito è situata sulla sponda sinistra del fosso strozzavolpe a poche decine di metri dal fosso fig. 1 localizzazione della necropoli della selvicciola nella placca di travertino di canino (viterbo). 1. formazione dei travertini; 2.substrato; 3. limite di formazione, a: certo, b: presunto; 4. scarpata di travertino su terrazzo fluviale, a:certa, b:presunta; 5. scarpata nei corpi di travertino, a: certa, b: presunta; 6. isoipsa; 7. corso d'acqua; 8. cono sorgentizio; 9. corpo fissurale; 10. cavità carsica e/o inghiottitoio; 11. sorgente; 12. traccia di profilo geologico. localisation of the selvicciola necropoli within the travertine plate of canino (viterbo). 1.travertine formation; 2. substrate; 3. limit of formation, a: evident, b: inferred; 4. scarp of travertine on fluvial terrace, a: evident, b: inferred; 5. scarp in travertine bodies, a: evident, b: inferred; 6. isohypse; 7. stream; 8. cone-type spring deposit; 9. fissure ridge deposit; 10. karst sinkhole and cave; 11. spring; 12. geological section. stesso (fig. 1). la stratigrafia locale è di difficile ricostruzione poiché tutta l'area è stata interessata da intensa attività antropica dalla preistoria ad oggi. particolarmente profonde sono state le modificazioni morfologiche e idrografiche attuate nell'area in seguito all'opera di bonifica iniziata successivamente al secondo conflitto mondiale. durante detta bonifica è stata quasi totalmente asportata la copertura travertinosa che poggiava sul substrato vulcanico, per permettere lo sfruttamento agricolo del suolo sottostante molto fertile, sviluppatosi su parent material vulcanico. lavori di sbancamento di questo genere si effettuano ancora oggi nelle zone di maggiore attività agricola. sono rimasti integri solo pochi lembi di travertino, in particolare quelli troppo spessi per poter essere rimossi o quelli connessi con coni sorgentizi o con canali profondi. nell'area del sito, infatti, sono conservate soltanto due strutture di travertino, distanti 100 m circa l'una dall'altra, allineate in direzione no-se, di forma tondeggiante o mammellonaretabulare. le due strutture, che presentano giacitura periclinale degli strati, più fortemente immergenti verso il fosso strozzavolpe, rappresentano ciò che rimane di due coni sorgentizi, nei quali si riconoscono ancora gli orifizi di emergenza delle acque, allineati secondo due sistemi di fratture verticali, orientati n55e e n60o (fig.2). la struttura orientale è stata quasi completamente smantellata e ridotta ad un ammasso isolato, ora molto vegetato, di blocchi di travertino, mentre quella occidentale ha subito l'asportazione della parte sudoccidentale fino al substrato, esposto lungo un taglio netto, verticale, lungo alcune decine di metri. proprio in questo tratto di substrato "scoperchiato", quasi a ridosso del taglio, è ubicata la necropoli attualmente in via di studio da parte degli archeologi, che secondo datazioni 14c su ossa umane è stata attiva dall'eneolitico fino all'i223elementi geologici sulla necropoli eneolitica ... nizio del bronzo antico (3500-2000 a.c.); mentre sulla parte nord-orientale del cono sorgentizio occidentale fino alla sponda sinistra dello strozzavolpe insiste una villa romana con annesse relative terme attribuita a un periodo repubblicano-imperiale, frequentata fino in tempi paleocristiani ed anche in periodo longobardo. la serie stratigrafica locale, messa in evidenza lungo il fosso strozzavolpe e in alcuni pozzetti conoscitivi scavati nel sito archeologico e profondi 2-4 m, è la seguente dal basso verso l'alto (fig.3a): a1) substrato vulcanico costituito da tufi stratificati con pomici; tufi pisolitici e cineritici predominanti nella parte inferiore, mentre in quella superiore prevalgono tufiti stratificate deposte in ambiente fluvio-lacustre. la parte sommitale del substrato vulcanico è interessata da una superficie di erosione molto incisa ed irregolare, con presenza di canalizzazioni e depressioni più o meno sviluppate. essa è interessata da: a2) sedimenti marnoso-argilloso-tufacei, misti a colluvio di suolo, sui quali si sviluppa un paleosuolo, di spessore molto variabile da pochi decimetri a qualche metro, dove non decapitato, di colore bruno-rossiccio, acalcareo, contenente frammenti di vulcaniti alterate. la parte alta di questo paleosuolo affiora anche sotto al travertino, laddove esso è stato interessato dal taglio netto a ridosso della necropoli e menzionato precedentemente. a3) copertura di travertino, a giacitura orizzontale o leggermente ondulata, di spessore variabile da pochi decimetri ad alcuni metri. presso le strutture sorgentizie e nel fosso strozzavolpe il travertino raggiunge uno spessore di 4-5 m ed oltre. la parte inferiore è costituita prevalentemente da sabbie e limi calcarei stratificati, alla base dei quali, a contatto con il substrato vulcanico, si notano livelli calcarei argilloso-marnosi di colore marroncino fino a nerastro, contenenti abbondante frazione detritica, rappresentata da granuli ossidati di vulcaniti e di minerali vulcanici (pirosseno, miche molto alterate, feldspati), di granuli di calcari e materiale organico. sono sterili, invece, dal punto di vista paleontologico. la parte superiore è costituita da banchi di travertino fitoermale e microermale, molto diagenizzati, compatti, di colore giallastro o marroncino,talora bruniccio, alternati a sottili strati di facies algali e batteriche, piuttosto porose e "sporche", con sviluppo locale di tessiture stromatolitiche a lamine chiare e scure. nei pressi dei coni sorgentizi sono diffuse le tessiture stromatolitiche a lamine sottili, con sviluppo di microvaschette a giacitura periclinale. le facies di travertino presenti nella sezione sembrano indicare per la parte basale un ambiente di sedimentazione prevalentemente fluviale, ad acque correnfig. 2 la struttura sorgentizia occidentale del sito con sistema di fratture verticali orientate n55e e n60o. sullo sfondo i resti della villa con terme di età repubblicanaimperiale. western spring structure affected by vertical fractures oriented n55e and n60w. in the background the remains of a roman villa and baths of republic-imperial age. 224 ti, scarsamente vegetato e sterile, con apporti variabili di materiale detritico allotigeno. la parte alta è caratterizzata da un ambiente prevalentemente palustre, con sviluppo di vasche e pozze ad acque poco mosse, in presenza, tuttavia, anche di locali episodi di acque sorgentizie con flussi correnti su pendio lieve, ben ossigenate e vegetate. in un'altra sezione ubicata a un centinaio di m a se della precedente e rappresentante la parte più superficiale della serie travertinosa, che copre in parte la necropoli, si osservano dal basso in alto (fig. 3b): b1) substrato vulcanico costituito da tufiti e limi tufacei giallastri, localmente cineritici, da fini a grossolani, interessati da una superficie di erosione ondulata che li incide irregolarmente. detti sedimenti sono alquanto rubefatti in superficie; localmente, nelle depressioni più accentuate, è presente lo stesso paleosuolo, bruno-rossiccio, acalcareo, descritto nel punto 2 della sezione precedente (vedere anche in fig. 5, simboli 3 e 4). b2) segue un banco di travertino di 2 m circa di spessore, costituito prevalentemente da facies microe fitoermali di colore marroncino, a strutture vegetali calcificate in posizione di crescita, con sottili alternanze ad andamento lenticolare di limi calcarei a fauna dulcicola, rappresentata da un'associazione a lymnaea stagnalis, lymnaea peregra e pseudoamnicola in proporzioni variabili e scarsi ostracodi. la parte superiore di detto banco di travertino passa verso l'alto a una facies detritica molto "sporca" e frammentata, mentre la parte inferiore è interessata da cavità carsiche irregolari, tappezzate da incrostazioni di cementi calcarei e piccoli speleotemi di deposizione tardiva. dette cavità sono parzialmente o completamente occupate da un suolo calcareo, marnoso-argilloso, bruno-nerastro, organico (fig. 4), contenente resti di fauna dulcicola simile a quella descritta precedentemente e una frazione detritica costituita da elementi spigolosi di travertino e di incrostazioni calcaree su supporto vegetale e da scarsi granuli di feldspato, di pirosseni neri e verdastri e rari granuli subarrotondati di quarzo. l'ambiente di sedimentazione sembra essere prevalentemente palustre ad acque poco mosse, in presenza, tuttavia, di episodi di acque correnti, ben ossigenate, vegetate e colonizzate da malacofauna dulcicola. llaa nneeccrrooppoollii la necropoli preistorica della selvicciola, scoperta nel 1987, è ancora in corso di esplorazione (cerilli et al., 1993; conti, persiani & petitti, 1997; petitti et al., 1999). a tutt'oggi comprende 31 tombe scavate e almeno 3 c. carrara, e. cerilli & v. verrubbi fig. 3 sezioni stratigrafiche nel sito; a) lungo il fosso strozzavolpe, b) nell'area orientale della necropoli. 1. suolo misto a frammenti di travertino; 2. suolo calcareo organico; 3. limi calcarei con fauna dulcicola; 4. travertino fitoermale e microermale; 5. limi e sabbie calcarei con lenti di materiale organico; 6. tufiti stratificate; 6a. paleosuolo 7. superficie di erosione; 8. campioni datati. stratigraphic sections: a) along the fosso strozzavolpe, b) in the eastern area of the site. 1.soil with travertine fragments; 2. calcareous organic soil; 3. calcareous silts with freshwater fauna; 4. phytohermal and microhermal travertine; 5. calcareous silts and sands with lenses of organic material; 6. reworked tuffs; 6a. palaeosol; 7. erosion surface; 8. dated sample. 225 ancora da scavare: si tratta di una delle necropoli più grandi attribuite alla cosiddetta cultura di rinaldone, ovvero alla facies classica dell'età del rame sul versante medio-tirrenico della penisola italiana. in base alle datazioni radiometriche effettuate su resti antropici può essere attualmente inquadrata tra la metà del iv millennio e la fine del iii millennio a.c. le tombe presentano l'aspetto tipico delle strutture funerarie di questo periodo; infatti si tratta delle cosiddette "grotticelle artificiali": pozzetti scavati perpendicolarmente al terreno consentono di accedere a piccoli ambienti ipogei a pianta ovale/circolare con volta arrotondata, la porta tra la camera ed il pozzetto veniva chiusa da lastre di travertino, bloccate da accumuli di pietre sistemati nel pozzetto prima che quest'ultimo venisse reinterrato (fig. 5). elementi geologici sulla necropoli eneolitica ... fig. 4 suolo organico bruno-nerastro nelle cavità della porzione superficiale della copertura travertinosa. the blackish-brown organic soil in the karstic cavities of the uppermost portion of travertine cover. fig. 5 ricostruzione ipotetica del piano di campagna al momento dello scavo delle tombe a "grotticella artificiale" (dall'archivio soprintendenza beni archeologici per l'etruria meridionale, modificata). 1. suolo e materiale detritico; 2. travertino; 3. paleosuolo; 4. tufiti stratificate; 5.vestibolo; 6. tomba sbarrata con lastra di travertino e massi accatastati contro; 7. sbancamento di età romanarepubblicana che ha determinato il fronte della basis villae. hypothetical reconstruction of ground surface at the moment of the excavation of "grotticella artificiale" type tombs (from archives soprintendenza beni archeologici per l'etruria meridionale, modified). 1. soil and detrital material; 2. travertine; 3. palaeosol; 4. reworked stratified tuffs; 5. vestibule; 6. tomb entrance blocked with a travertine slab and boulders; 6.cut from the roman-republic age that determined the front of basis villae. 226 l'elemento di novità apportato dallo scavo e dallo studio della selvicciola è costituito da una visione radicalmente nuova dei rituali di deposizione e quindi dei processi di formazione dei depositi archeologici: infatti puntuali tecniche applicate allo scavo hanno documentato un rituale che prevedeva anche più di un intervento sulle ossa già scarnificate, con il disturbo dell'ordine anatomico, la dislocazione dei resti umani, a volte anche il rimescolamento tra resti di individui diversi. purtroppo le vicissitudini subite non solo dalla selvicciola ma anche da altre necropoli eneolitiche non consentono al momento di capire se, oltre a questa realtà ipogea, la necropoli comprendesse anche strutture e spazi sulla superficie del terreno: la ricostruzione dei processi di deposizione degli inumati induce in realtà ad ipotizzare che la necropoli arrivata fino a noi corrisponda solo ad una parte di un complesso più ampio. eelleemmeennttii ccrroonnoollooggiiccii ee ddiissccuussssiioonnee un campione prelevato dai livelli argilloso-marnosi contenenti materia organica brunastra alla base del travertino affiorante lungo il fosso strozzavolpe, a contatto con il substrato vulcanico, è stato datato con il metodo 14c:l'età convenzionale è risultata 10680+/-260 bp (cal bp 13180-11860, stuiver et al., 1998; beta analytic inc.-145524). si può presumere, quindi, che, nell'area considerata, il travertino abbia cominciato a deporsi sopra il substrato vulcanico più o meno rimaneggiato ed inciso, verso la fine del tardiglaciale. la fase erosiva precedente alla venuta del travertino nell'area della selvicciola può essere correlata con quella messa in evidenza a poggio olivastro e altrove nell'area di canino (carrara, 1994). l'età ottenuta rappresenta, quindi, un ulteriore conferma della presenza, nell'area in studio, di un'importante e lunga fase erosiva che, sebbene non sia esattamente coeva in tutte le parti dell'area, si situa generalmente tra la fine del pleistocene superiore e l'olocene. un campione del suolo bruno-nerastro organico contenuto nelle cavità carsiche della serie travertinosa superficiale che ricopre in parte la necropoli eneolitica (sezione b2) ha dato un'età radiocarbonio di 2770+/-45 bp (cal bp 2956-2774, stuiver et al., 1998; scottish univ.aa-44394). detta datazione indica probabilmente un termine comprensivo della deposizione del travertino alto, che è andato soggetto, durante la deposizione, non solo a fenomeni carsici di dissoluzione e riprecipitazione, ma anche alla formazione del suolo organico datato. generalmente, infatti, i processi di questo tipo iniziano immediatamente dopo la deposizione del travertino o, addirittura, sono contemporanei alla stessa (carrara, 1998) e si influenzano a vicenda. il processo carsico potrebbe essere stato innescato dall'abbassamento della falda causato dall'inizio dell'incisione fluviale ed essere stato favorito, inoltre, dalla pedogenesi. se ne deduce che, all'atto dell'impostazione della necropoli (circa 3500 a.c./ 5500 bp), l'area era già parzialmente ricoperta da travertino, che ha continuato a deporsi fino a prima di 3000 anni bp circa. ciò, da un lato permette di affermare che le tombe della necropoli sono state scavate nelle tufiti stratificate del substrato sotto il travertino, che fungeva da tetto compatto e resistente delle stesse (senza il quale le tombe sarebbero state velocemente cancellate dall'erosione, data la scarsa coesione e compattezza dei sedimenti tufacei), dall'altro lato ci permette di ipotizzare che durante la frequentazione della necropoli e successivamente, in alcune parti dell'area in studio, doveva essere ancora presente una certa attività sorgentizia, che dava luogo a locali e modesti corpi di travertino. non si può escludere, peraltro, che le acque fossero utilizzate e controllate dall'uomo, come è avvenuto in altre località (carrara, ciuffarella & paganin, 1998) e come suggerisce la presenza nell'area della necropoli di una villa con annesse relative terme di età repubblicana-imperiale, poste nelle immediate adiacenze della necropoli. la placca di travertino lungo il fosso strozzavolpe è fortemente dissecata; il torrente ha inciso non solo tutto lo spessore del travertino, ma si è approfondito nel substrato vulcanico nel quale attualmente scorre, a una decina di metri sotto il livello della superficie sommitale della placca. la fase erosiva lineare,che ha interessato l'area di deposizione del travertino, dato il carattere netto, non degradato, subverticale delle pareti delle incisioni, deve essere stata intensa e continua; probabilmente è ancora in corso, visto che sul letto del torrente si osservano soltanto scarsissimi ed esigui depositi alluvionali e che attualmente l'incisione del fosso strozzavolpe provoca il crollo di una parte delle strutture della villa romana. cronologicamente, quindi, la fase erosiva si colloca nel tardo olocene, in corrispondenza di una fase di notevole diminuzione e/o cessazione completa della deposizione del travertino, già osservata e descritta in altri luoghi nello stesso periodo di tempo (carrara, 1994 e 1998). ccoonncclluussiioonnii le tombe della necropoli della selvicciola, attiva dall'eneolitico al bronzo antico (3500-2000 a.c.), sono state scavate al di sotto di una copertura di travertino, dello spessore variabile da pochi decimetri ad alcuni metri, al contatto del substrato vulcanico pleistocenico dei monti vulsini, costituito da tufi rimaneggiati intensamente pedogenizzati ed interessati da un'evidente superficie di erosione areale, presente in tutta l'area di canino, cronologicamente compresa tra la fine del pleistocene superiore e l'olocene. la deposizione del travertino è iniziata con sabbie e limi calcarei misti a materiale argilloso e detritico più grossolano con sottili livelli di materia organica, per proseguire poi con facies fitoermali e microermali prevalenti. la parte più alta della copertura di travertino è rappresentata da facies microe fitoermali "sporche", alternate a livelli di limi calcarei a fauna dulcicola ed è interessata da cavità carsiche irregolari, tappezzate da incrostazioni di cementi tardivi e riempite da un suolo organico bruno-nerastro. datazioni radiocarbonio sui livelli organici della base e della parte alta della placca di travertino suggeriscono che il deposito nell'area del sito abbia cominciato a formarsi verso la fine del tardiglaciale (cal bp 1318011860) per proseguire fino al tardo olocene (cal bp 2956-2774), allorché subentra una fase di stasi nella deposizione; fase, peraltro, nota in altre località di affioramento di depositi di travertino e connessa con più fattori di carattere idro-geologico e climatico, nonché con c. carrara, e. cerilli & v. verrubbi quello antropico (goudie,viles & pentecost, 1993). più o meno contemporaneamente l'area è soggetta ad un'intensa fase erosiva lineare che approfondisce notevolmente la rete idrografica, disseccando la copertura di travertino ed innescando in essa fenomeni carsici, favoriti oltretutto dal processo pedogenetico. rriinnggrraazziiaammeennttii gli autori ringraziano la s.a.e.m. per il consenso alla pubblicazione e la dr.ssa patrizia petitti per le notazioni archeologiche. aauuttoorrii cciittaattii carrara c.(1994) i travertini di canino (viterbo, italia centrale): elementi di cronolitostratigrafia, di geochimica idotopica e loro significato ambientale e climatico. il quaternario, 77(1), 73-90. carrara c. (1998) i travertini della valle del pescara tra popoli e tor de' passeri (abruzzo, italia centrale). il quaternario, 1111(2), 163-178. carrara c., ciuffarella l. & paganin g.(1998) inquadramento geomorfologico e climaticoambientale dei travertini di rapolano terme (si). il quaternario, 11(2), 319-329. cerilli e;, conti a. m., macchiarelli r., persiani c., petitti p. & salvadei l. (1993) rapporto preliminare sugli scavi eseguiti nella necropoli eneolitica della selvicciola (ischia di castro). preistoria e protostoria in etruria atti del i incontro di studi, la cultura di rinaldone ricerche e scavi, 75-84. conti a. m., persiani c. & petitti p. (1997) i riti della morte nella necropoli eneolitica della selvicciola (ischia di castro, viterbo). origini, 2211, 169-185. goudie a.s., viles h.a. & pentecost a. (1993) the late-holocene tufa decline in europe.the holocene, 33(2), 181-186. petitti p., cerilli e., conti a. m. & persiani c. (2000) la necropoli eneolitica della selvicciola (ischia di castro vt): i nuovi scavi. in: recenti acquisizioni, problemi e prospettive della ricerca sull'eneolitico dell'italia centrale, atti dell'incontro di studio, arcevia 14-15 maggio 1999, a cura di m. silvestrini, 179-189. stuiver m., reimer p. j., bard e., burr g. s., hughen k. a., krome b., mckormac g., van der plicht j. & spurk m. (1998) intcal98 radiocarbon age calibration, 24.000-0 bp. radiocarbon, 4400, 10411083. 227 ms. ricevuto il 1° settembre 2002 testo definitivo ricevuto il 22 ottobre 2002 ms. received: september 1, 2002 final text received: october 22, 2002 elementi geologici sulla necropoli eneolitica ... imp.giraudi mmiiddddllee pplleeiissttoocceennee ttoo hhoolloocceennee aappeennnniinnee ggllaacciiaattiioonnss ((iittaallyy)) ccaarrlloo ggiirraauuddii enea, p.o. box. 2400, 00100 roma a.d. abstract knowledge of the apennine glaciations may be summarized as follows: it is certain that in the apennines there are traces of at least one glacial expansion older and more extensive than that of the last glacial maximum (lgm). its age is not known in detail, but it is highly likely that it dates from the final part of the middle pleistocene. an additional earlier glacial phase might also be represented. the late pleistocene glaciation has left few traces relating to marine isotope stage 4, but abundant sediments and features relating to the lgm and to its recessional phases are found. radiometric dating of these glacial oscillations is still rather scanty. in the last few years tephra layers and some eolian deposits have been found which, being isochronous, make it possible to obtain a chronological setting and a precise correlation even between the moraines situated at latitudes and elevations very different from one another. the late pleistocene lgm glaciers started to expand earlier than 22,680±630 14c years bp (campo imperatore stadial), and began to retreat slowly around 21,500 14c years bp, and then more rapidly until about 17,000 14c years bp. after 17,000 years bp there was a readvance. this fontari stadial was followed by recessional phases lasting until after 11,760 ±160 14c years bp. another readvance followed, the mount aquila stadial, which may be correlated with the younger dryas. the recessional phases of this stadial are probably represented by the earliest holocene moraines: later the glaciers melted. they reformed in the second half of the holocene (calderone stadial) after 3890±60 14c years bp, and re-expanded after ca. 2650±60, 1450±40, 670±40 14c years bp and reached their maximum length during the little ice age. the calderone glacier, the only one that now exists in the apennines, has strongly melted back in the 20th century. riassunto le conoscenze relative alle glaciazioni dell'appennino possono essere sintetizzate nel modo seguente. e' sicuro che sull'appennino vi sono le tracce di almeno una espansione glaciale più estesa di quella dell‘ultimo massimo glaciale: la sua età non è nota in dettaglio, tuttavia è molto probabile che risalga al pleistocene medio, forse alla sua parte finale. potrebbe essere documentata anche una fase glaciale precedente, per la quale risulta difficile una attribuzione cronologica. la glaciazione del pleistocene superiore ha lasciato poche tracce relative allo stadio isotopico 4, ma moltissimi depositi e morfologie relativi all‘ultimo massimo glaciale ed alle sue fasi di ritiro. i ghiacciai della fase finale del pleistocene superiore si sono espansi a partire da un momento precedente a 22,680±630 anni 14c bp (campo imperatore stadial), ed hanno cominciato a ritirarsi lentamente attorno a 21,500 anni 14c bp, e poi, più velocemente, fino a circa 17,000 anni 14c bp. in un periodo poco più recente di 17,000 anni 14c bp vi fu la riespansione glaciale denominata fontari stadial, seguita da fasi di ritiro che durarono fino ad un momento più recente di 11,760±160 anni 14c bp. si verificò poi la riespansione glaciale denominata m. aquila stadial, correlabile al younger dryas: le fasi di ritiro di questo stadio dovrebbero essere rappresentate dalle prime morene oloceniche. per quel che riguarda le espansioni glaciali oloceniche e la neoglaciazione occorre tenere presente che i dati sono scarsi poiché le località studiabili sono pochissime e ristrette alle porzioni più elevate dei due massicci più elevati dell'appennino. i ghiacciai presenti nella fase iniziale dell'olocene scomparvero e si riformarono poi nella seconda metà dell'olocene in un periodo più recente di 3890± 60 anni 14c bp, furono soggetti a varie fasi di espansione dopo 2650±60, 1450±40, 670±40 anni bp (calderone stadial) e raggiunsero la loro massima lunghezza nel corso della piccola età glaciale. il ghiacciaio del calderone, l'unico attualmente presente sull'appennino, ha mostrato nel corso del xx secolo una forte riduzione di volume ed appare sull‘orlo dell‘estinzione. key words: apennines, glaciations, middle pleistocene, late pleistocene, holocene. il quaternario italian journal of quaternary sciences 1166(1bis), 2003, 37-48 iinnttrroodduuccttiioonn the apennines form the backbone of the italian peninsula, extended into the mediterranean sea between 38° n and about 44°30’ n (fig. 1). traces of former glaciation have been known for the apennines since the 19th century and have been the subject of many investigations. in the present work, however, only the most recent studies will be taken into consideration. the highest peaks in the apennines are found in the central sector, between about 42°50’ n and 41°30’ n where they include the gran sasso (2912 m), maiella (2793 m), velino (2486 m), sibillini (2476 m) and laga (2458 m) massifs, but numerous other peaks exceed 2000 m. in contrast, the mountains of the northern apennines exceed 2000 m only at mounts cusna (2121 m), cimone (2165 m) and prato (2054 m), and the mountains of the southern apennines exceed 2000 m only in mounts sirino (2005 m) and pollino (2266 m). at present only a single small glacier which is rapidly melting is found in the apennines: the calderone glacier in the gran sasso. until around 15 years ago, the study of the apennine glaciations was limited to examination of the glacial features, the weathering of the till and calculation of the equilibrium line altitude (ela) of the former glaciers. the chronological framework of the glacial phases relied largely on the correlation between the local ela and those of the alps. it is only since 1989 that the use of 14c dates and of tephra layers (frezzotti & narcisi, 1989, frezzotti & giraudi, 1989) has made it possible to date the glacial deposits directly, although as yet only 38 c. giraudi very few dates are available. in the apennines there are traces of at least two glaciations: the most ancient ones, while certain, are rather scanty, whereas traces of the most recent glaciation are very abundant and well preserved. the great majority of the glaciers were present in valleys and glacial cirques orientated towards the north, while only a few developed in valleys orientated towards the west and the east, and hardly any occurred in valleys with a southern alignment. mmiiddddllee pplleeiissttoocceennee ggllaacciiaattiioonn it is only recently that the traces of an early glaciation were identified with certainty (federici, 1977). since the glacial stratigraphy of the apennines has been correlated with that of the alps, the oldest moraines have been attributed to the rissian glaciation or to a generic pre-würmian event. pre-würmian moraines have been reported from the northern apennines, in the area of mount navert (federici, 1977; jaurand, 1994, 1998), and in the central apennines, at sibillini massif (coltorti & farabollini, 1995), at campo imperatore in the gran sasso massif (giraudi, 1994; jaurand, 1994, 1998; giraudi & frezzotti, 1997; bisci et al., 1999), in various places of the velino massif (cassoli et al., 1986; giraudi, 1998b) and at mount greco (frezzotti & giraudi, 1989; cinque et al. 1990). according to damiani & pannuzi (1991), however, the 'rissian' moraines at mount greco should be attributed to the early würmian glaciation. judging from the distribution of till in the central italian massifs, the extension of the glaciers during this period must have exceeded that of the last glacial maximum (lgm) by some 5 10%. it is not possible to assess the ela of the glaciers because the apennine chain has been affected by intense neotectonic movements, and it is likely that the characteristics of the catchment areas of the glaciers have changed considerably. overall the data are so scanty that no glacial limits can be mapped. according to kotarba et al. (2001), uranium series datings have been done on calcite crystals included in fig. 1 location of the apennine chain and of the main mountain massifs. legend: 1 areas above 1000 m; 2 present shoreline; 3 last glacial maximum shoreline. moraine deposits at campo imperatore: the ages of 121 (+13/-12) and 135 (+10/-9,7) allow the authors to assume a late-middle pleistocene age for the older glaciation phase. in a recent study (giraudi, 1998b) of the campo felice area in the velino massif (central apennines), the relative age of some of the older moraines were determined. these 'rissian' glaciation moraines are overlain by aeolian deposits which mainly include volcanic minerals. they contain a palaeosol. in addition, these deposits have also yielded a mousterian chert artefact. in central italy mousterian cultural remains occur from at least marine isotope substage 5e (i.e. eemian) and until the end of mis 4 (i.e. middle würmian). since the moraines predate the aeolian deposits, the palaeosol and the artefacts, it is highly improbable that the ice advance occurred during mis 4 and 5 (i.e. early or middle würmian). the first major ice advance in the apennines must therefore date at least from one of the cold stages preceding mis 5e; it must be middle pleistocene. because the moraines are fairly well preserved, a late middle pleistocene age is most likely (i.e. potentially mis 6 or 8). according to jaurand (1994, 1998), the mount navert moraine, another pre-würmian feature that was preserved in a palaeolandscape, may be even older. it might indicate glaciation of the apennines before the late middle pleistocene. uuppppeerr pplleeiissttoocceennee ggllaacciiaattiioonn,, tthhee llaasstt ggllaacciiaall mmaaxxiimmuumm aanndd iittss rreettrreeaatt pphhaa-sseess traces of the upper pleistocene glaciation have been reported in a number of papers, but only the most recent will be considered. the considered works on the northern apennine glaciers are: bertolini & trevisan (1984), braschi et al. (1986), castaldini et al. (1998), federici (l977, 1978, 1981), federici & scala (1966), federici & tellini (1983), gabert (1962), giglia (1967), gruppo ricerca geomorfologia (1982), jaurand (1994, 1998), losacco (1982), nardi (1961), pelletier (1959), suter (1950) and trevisan et al. (1971). the works on the central apennines glaciers are by bally (1954), biasini (1966), brancaccio et al. (1980), cassoli et al. (1986), castaldo (1965), catenacci (1974), cinque et al. (1990), damiani (1975), damiani & pannuzi (1976, 1979, 1985-1986 a,b, 1991, 1993), demangeot (1965), dramis & kotarba (1994), dramis et al. (1987), dramis et al. (1980), federici (1979, 1980), frezzotti & giraudi (1989, 1990, 1992), frezzotti & narcisi (1989, 1996), giraudi (1988, 1989a, 1989b, 1992, 1994, 1997a, 1997b, 1997c, 1997d, 1998 a, 1998b, 1998c, 1998d, 2000), giraudi & frezzotti (1995, 1997), jaurand (1994, 1998), mongini (1970), palmentola et al. (1990), pfeffer (1967), praturlon (1968), raffy (1983), rasse (1994) and tagliaferro (1982). the works on the southern apennines glaciers are by boenzi & palmentola (1971, 1972a, 1972b, 1974, 1975), giraudi (1998f), lippmannprovansal (1987), palmentola & acquafredda (1983), palmentola et al. (1990) and palmentola & pennetta (1979). savelli et al. (1995) report the presence of glacial 39middle pleistocene to ... remains on mount catria (1700 m a.s.l., north-central apennines). as the authors point out, the glacial traces on mount catria are somewhat problematic and they lack age control. the glacier is said to have developed in a south-facing valley and its front must have reached down to an extremely low level (about 580 m a.s.l.), far lower than the levels reached by the major glaciers of the northern apennines with a northern exposure. glacial landforms are absent from the highest peak of the mountains, which is exposed to the west, and is theoretically best suited to support a glacier. therefore, this supposed past glacier cannot be discussed until new evidence becomes available. upper pleistocene glacial morphological features and deposits can almost exclusively be dated to the last glacial maximum and its retreat phases. older outwash sediments have only been identified (frezzotti & giraudi, l992) from the margins of the velino massif (central apennines). these sediments predate a fossil soil on volcanic material, dated to 33,140±1700 14c years bp and developed, probably, during marine isotopic stage 4. the most recent summaries of data on the late pleistocene glaciation of the apennines were presented by federici (1979) for the central and northern apennines, palmentola et al. (1990) for the southern apennines and jaurand (1994, 1998) for the whole mountain range. federici (1979), using the degree of preservation of the landforms, but without any radiometric dates, correlated the moraines of the maximum ice advance of the central apennines to the 'würm iii' of the alps. this expansion was related by him to between c. 21,000 and 18,000 years bp. he also differentiated various successive retreat stages: apennine stage 1, correlated with the alpine altstadien, which is marked by a rise of the equilibrium line altitude (ela) of 110-240 m; apennine stage ii, correlated with the bühl-schlern stages of the alps, with ela 300 m higher than 'würm iii'; apennine stage iii, correlated with the gschnitz of the alps, with ela about 600 m higher than 'würm iii'; apennine stage iv, correlated tentatively with the daun of the alps, with ela about 700-800 m higher than 'würm iii'. according to panizza (1985), the alpine bühlschlern and gschnitz stages are included in the oldest dryas, while the daun corresponds to the older dryas. in the southern apennines, palmentola et al. (1990), again in the absence of absolute dates, correlated the maximum ice advance to the alpine würm iii and distinguished three successive retreat stages: apennine stage 1, which they correlated with the oldest dryas, with an ela of about 150-170 m higher than würm iii; apennine stage ii, which they correlated with the older dryas, in which an ela of about 300 m higher than in würm iii was determined, and apennine stage iii, which they correlated with the younger dryas, with an ela about 400 m higher than during würm iii. later, frezzotti & giraudi (1989, 1992) dated the late-glacial climatic phases in the area of mount greco and the outwash sediments of mount velino (central apennines). for the first time they were able to demonstrate that the apennine lgm was more recent than a 40 series of depositional and erosional events younger than c. 30,000 14c years bp but older than c. 15,000 14c years bp. lowe (1992) dated lacustrine sediments behind a number of stadial moraines in the northern apennines. following study of the glacial events throughout the apennines, jaurand (1994, 1998) based his synthesis on a number of radiocarbon dates reported in frezzotti & giraudi (1989, 1992) and lowe (1992). jaurand (1994, 1998) attributed the lgm moraines to an ice advance which reached its maximum around 19,000 14c years bp. he recognized four successive stages: apennine stage i, which corresponded to a rise of the ela of 50-125 m; apennine stage iia, correlated with the oldest dryas, older than 13,000 14c years bp, with a rise of the ela of 250-300 m; apennine stage iib, which he correlated with the younger dryas, with a rise of the ela of about 400 m and apennine stage iii, correlated with the preboreal, with a rise of the ela of 550-600 m with respect to that of the last glacial maximum (lgm). regarding the southern apennines, jaurand (1994, 1998) denies, on the basis of sedimentological and morphological evidence, the glacial origin of deposits in calabria, south of mount pollino formerly postulated by boenzi & palmentola (1972b, 1974, 1975b). more recently, giraudi (1997a, 1997b, 1997c, 1997d, 1998 a, 1998b, 1998c, 1998d, 2000, in the press) and giraudi & frezzotti (1997) carried out more detailed investigations on a number of massifs in the central apennines (gran sasso; greco, terminillo, velino, maiella, breccioso, matese) and in the southern apennines (sirino and pollino). on the gran sasso massif, thanks to a series of radiocarbon dates and the neapolitan yellow tuff tephra (recognized by frezzotti & narcisi, 1989, 1996), giraudi & frezzotti (1997) were able to date various phases of the lgm (campo imperatore stadial). the longest glacier in the apennines had already reached its maximum extent before 22,680±630 14c years bp. its glacier tongue blocked a small tributary valley, damming a proglacial lake. glacial retreat began around 21,450±250 14c years bp, when outwash was deposited. a further phase of intense glacial melting is again dated from outwash deposits to a little less than 17,840±200 14c years bp. moreover, many recessional moraines are recognized: all of which, except the highest on mount aquila, predate the neapolitan yellow tuff tephra, dated at 12,300±300 14c years bp (alessio et al., 1973). the authors were able to distinguish two interstadial periods, the fornaca interstadial, at 1617,000 14c years bp, and the venacquaro interstadial, radiocarbon-dated to 13,000 11,000 years bp. giraudi & frezzotti (1997) summarize the sequence of events as follows: • in addition to the last glacial maximum (lgm) moraines of the campo imperatore stadial, on the gran sasso there are three recessional moraines that predate the fornaca interstadial. • afterwards these interstadial glaciers readvanced during the fontari stadial. a set of three recessional moraines formed prior to the subsequent venacquaro interstadial. • this was followed by a minor glacial readvance in the monte aquila stadial, after 11,760±160 and before 8035±140 14c years bp, which may be correlated with the younger dryas. despite having no new 14c dates available, giraudi (1997a, 1997b, 1997c, 1997d, 1998a, 1998b, 1998c, 1998d, 2000) in his studies of other massifs in the central-southern apennines recognized a number of stratigraphic markers (tephra and aeolian sediments) which are fundamental for the dating and correlation of the glacial events on the different massifs. later on, new data about tephra layers found on glacial debris allowed the number of stratigraphic markers, described below, to be improved. in all the glaciated areas studied (except for the gran sasso and majella), the most recent moraines (ela some 400-475 m higher than that of the lgm) are overlain by the neapolitan yellow tuff tephra, radiocarbon dated 12,300±300 14c years bp (alessio et al., 1973). on the matese massif (central apennines) a tephra layer predating the neapolitan yellow tuff overlies moraines which indicate a rise of the ela of c. 300 m with respect to the lgm. the tephra was analyzed by narcisi (2000, personal communication) using sem analysis: the chemical composition appears very similar both to the tephra of the "greenish" and "basale" eruptions of mount vesuvius. near the volcano, the products of the "greenish" eruption cover palaeosols dated 15,500±170 and 14,420±160 14c years bp (santacroce, 1987), and the tephra of the "basale" eruption covers palaeosols dated 16,250±130 and 17,050±40 14c years bp (delibrias et al., 1979) in all glaciated areas, at the bottom of closed depressions on glacial debris, a layer of loess was found. on mounts greco and matese (central apennines) and on mount sirino (southern apennines), this loess consists mainly of quartz. it is the only loess with such a mineralogical composition known in the centralsouthern apennines in the last 30,000 years bp. here it overlies moraines which indicate a rise of the ela of c. 200-280 m with respect to the lgm, but is not present on the younger ones. the precise age of this loess, identified for the first time by frezzotti & giraudi (1989, 1990), is lacking, but its dating is based on the following criteria: • on the aremogna plain (mount greco central apennines) the loess lies on outwash sediments deposited during the lgm recession. on the basis of the data collected by giraudi & frezzotti (1997) on the gran sasso massif, the outwash deposits were, partly, formed after 17,840±200 14c years bp. at the fucino plain, the deposition of outwash sediments from the glacier of the velino massif ended around 17,380±160 14c years bp when the lake covered a soil and produced erosion on such deposits (giraudi, 1998g). on the aremogna plain, the loess, which has been subject to soil formation, was redeposited as colluvium and subsequently overlain by peat dated at 12,850±200 14c years bp (frezzotti & giraudi, 1989). • on mount matese (central apennines) the loess is older than the tephra layer (giraudi, 1997a). similar to the products of the "greenish" and "basale" eruption of vesuvius, datable at c. 14,000-15,000 and 16,000-17,000 14c years bp. the cerchio tephra, a tephra of as yet unknown oric. giraudi 41 gin, was identified on the moraines of the first recessional phases after the lgm (with an ela some 125 m higher than at the lgm) of mount breccioso (central apennines). the first products of tephra reworking have been dated in the nearby fucino plain (giraudi, 1995) at 19,100±650 14c years bp. about the tephra layers that predate neapolitan yellow tuff on the matese massif, and overlie the quartz-rich loess, one can observe that, due to the age of the eruption, there is little probability that it corresponds to the "basale" eruption of vesuvius. the "basale" covers palaeosols dated 16,250±130 and 17,050±40 14c years bp and seems too old to fit in with the chronology of the glacial phases suggested by other datings. otherwise one must assume that during the short period between 17,380±160 and 16,000 – 17.000 14c years bp a glacial re-expansion occurred, with the sedimentation of the quartz-rich loess, and a new retreat phase. it is therefore assumed that the tephra predating the neapolitan yellow tuff on the matese massif pertains to the "greenish" eruption of vesuvius, younger than palaeosols dated 15,500±170 and 14,420±160 14c years bp . following this assumption, one can date the quartz-rich loess, covering moraines of a glacial stadial when ela was 200-280 m higher with respect to the lgm, to a period around or slightly younger than 16,000 14c years bp. using radiocarbon dating and the chronological data stated above, a chronology of the apennine last glacial maximum and its retreat phases has been obtained (fig.2). the maximum glacial extent, i.e. the campo imperatore stadial, was reached just before 22,680 ±630 14c years bp and lasted until ca. 21,450±250 14c years bp. during lgm, ela on the apennines was conditioned by latitude and valley exposures, and varied between 1250 and 1900 m a.s.l. about 21,450±250 14c years bp the glaciers started the early phases of retreat, that lasted until 17,840±200 14c years bp. in this period at least two retreat moraines were formed, produced by glaciers having ela 15-125 and 110-200 m higher than lgm; nevertheless in some massifs the retreat moraines can be three or more because of local topographic reasons. around 17,840±200 14c years bp a very marked retreat phase took place, and a large amount of outwash sediments was produced: such a rapid glacier melting must have been due to a strong climatic change, i.e. to the occurrence of an interstadial (fornaca interstadial). the glacier melting ceased around 17,380±160 14c years bp, when a new stadial advance took place (fontari stadial). during this stadial the last valley glaciers were present on the higher massifs, and ela was 200-280 m higher than during lgm. starting from 16,000 14c years bp, a glacial reduction took place. two retreat moraines were formed: the former, dated about 15.000-16.000 14c years bp, by glaciers having ela 290-390 m higher than during lgm, and the latter, dated around 14,000 14c years bp, by glaciers having ela 400-475 m higher than during lgm. between 12,850±200 14c years bp and at least 11,760±160 14c years bp, the lack of glacial remnants and the presence of lakes in some former glacial cirques (giraudi & frezzotti, 1995) suggest a very small extension of the glaciers. this time lapse is called venacquaro interstadial and corresponds to the böllingalleröd interstadial. later, between 11,760±160 and 8035±140 14c years bp, a new small glacial advance took place (m. aquila stadial) corresponding to the younger dryas chron. it is clear that the dates obtained generally show an earlier age for the glacial events than assumed before. hhoolloocceennee nneeooggllaacciiaattiioonn the presence of glaciers in the apennines during the holocene is shown by the calderone glacier. this glacier, located on the gran sasso massif, is the southernmost in europe (gellatly et al.,1994). it is found at an elevation above c. 2670 m in a cirque situated on the northern slope of the corno grande (2912 m). its tongue is rapidly melting and is almost completely covered by debris, but it was still some 15 m thick in its lower part (gellatly et al.,1994; fiucci et al., 1997). the glacier is situated at the head of the cornacchie valley. here new investigations have begun; in the upper part there are some moraines, which were formed by glaciers with an ela more than 800-1050 m higher than that of the lgm. they must be of holocene age, because the younger dryas ela was at least 250 m lower. there are no precise dates for these oldest holocene moraines: the only chronological indication is provided by a sequence of colluvial sediments and soils overlying the till that include a tephra layer. the tephra, of uncertain provenance, may be correlated mineralogically with the duchessa tephra (giraudi, 2001). this unit has also been found on other moraines in the central apennines, and overlies soils dated to 4390±50 (beta 117017), 4220±80 (beta 106450) and 4020±70 (beta 111004) 14c years bp. the moraines, which indicate a glacier with an ela about 800 m higher than that of the lgm, may possibly represent the recessional phases of the mount aquila stadial dated to the younger dryas chron. the moraines situated at the threshold of the calderone glacier cirque, with their ela about 10001050 m higher than the lgm, have been attributed to the little ice age (lia) by various authors (federici, 1979; jaurand, 1994, 1998; gellatly et al., 1994). in the course of new observations on these moraines, three different tills have been recognized (giraudi, 2000, 2002). the oldest till, almost completely covered by the successive units, has a dark grey matrix of silt rich in organic matter, derived from a soil on volcanic material. its mineralogical composition is analogous to that of the duchessa tephra. the organic matter has been dated to 3890±60 14c years bp. consequently, the glacial advance (calderone 1 stadial) that formed the moraine must be younger than that date and represents the first known apennine neoglacial expansion. in view of the very steep sides of the glacial cirque, the soil could only be derived from the cirque, which is currently occupied by the glacier. therefore, starting from about 4300 14c years bp and until around 3890 ±60 14c years bp, the middle pleistocene to ... 42 c. giraudi fig. 2 chronological framework of the last glacial maximum, late pleistocene and holocene apennine glacial stadials. calderone glacier was absent or was definitely much smaller than at present. but according to others palaeoclimatic data on the central apennines area and the correlations with alpine glacial phases, giraudi (2000) hypotesized that the glaciers on the apennines disappeared about 9000 14c years bp. in order to detect the age of the debris of glacial origin lying just down-valley of the threshold of the cirque of calderone glacier, giraudi (2002) dated the interbedded soils by means of radiocarbon analysis. the datings point out four more glacial expansions: the first (calderone 2) following 2650±60 14c years bp, the second (calderone 3a) bracketed between 1450±40 and 670±40 14c years bp, the tird (calderone 3b) following 670±40 14c years bp, the last one (calderone 3c) datable to the xix century. the calderone 3b expansion, occurred during the little ice age, can be considered the neoglacial maximum. thus, the following sequence of events has been deduced: the early holocene saw the recessional phases of the mount aquila stadial glaciers. after 9000 14c years bp, these glaciers melted completely. subsequently the calderone glacier expanded, after 3890±60, 2650±60, 1450±40, 670±40 14c years bp and during the xix century. moraines colonized by only very little vegetation, are also preserved at high altitudes at a number of valley heads in the maiella massif (central apennines). they have been attributed to the holocene (giraudi, 1998e). at the head of the cannella valley, an extremely small moraine situated at 2540 m is almost completely devoid of vegetation, comparable to the till of the calderone glacier attributed to the lia above-mentioned. it is therefore probable that in this valley a small glacier also formed during the lia. traces of neoglaciation are probably found on only the two highest massifs of the apennines, since the peaks of the other massifs are below the altitude of the calderone stadial moraines. ccoommppaarriissoonn bbeettwweeeenn tthhee aappeennnniinnee,, aallppiinnee aanndd ootthheerrss mmoouunnttaaiinn ggllaacciiaattiioonnss the comparison between the apennines and other mountain chain glacial expansions can be reliable only for lgm and holocene, because the older glaciations lack a suitable chronological framework. the upper pleistocene maximum glacial expansion, dated in the apennines between 22,680±630 and 21,450±250 14c years bp, was not synchronous in the european mountain chains. in the pyrenees lgm occurred in a period older than 38,000 14c years bp, and a secondary glacial expansion took place ca. 26,000 14c years bp (jalut et al. 1992; florinet & schlüchter, 2000). on the massif central, lgm occurred before 28,000 14c years bp, while a minor expansion took place ca. 18,000 14c years bp (etlicher & de goer de hervé, 1988; florinet & schlüchter, 2000). on the jura, lgm is dated between 25,000 and 15,000 14c years bp (campy & richard, 1998). in the northern alpine foreland lgm was reached in a time lapse between 28,000 e 20,000±1800 14c years bp (ivy-ochs, 1996; florinet & schlüchter, 2000), while in the southern alpine foreland it took place between 24,000 and 17,700±360 14c years bp (fliri, 1989, orombelli, 1974; bini, 1997). the lgm datings in the apennines, the alps and the jura are essentially similar. although the beginning of the glacial retreat in the italian alps (17,700±360 14c years bp according to orombelli, 1974) clashes with the start of the fast retreat of the apennine glaciers (ca.17,840±200 14c years bp), in the apennines a slow glacial melting occurred after ca 21,450±250 14c years bp. the early apennine glacial retreat was produced by a climatic change from cold and wet to cold and dry (giraudi & frezzotti, 1997). this change probably occurred only in the italian peninsula, not in the alps, or the climate change was weak and not able to affect the alpine glacial system having greater inertia. according to florinet & schlüchter (2000) the different chronological framework for the pyrenees and the vosges lgm is the consequence of palaeoclimatic conditions linked to some differences in the upper pleistocene atmospheric circulation. about holocene, baroni & orombelli (1996), orombelli & mason (1997), grove (1997), grove & gellatly (1997) and jania (1997) report that between 9000 and 8000 14c years bp in the alps, the pyrenees and the tatramountains, the largest glaciers were smaller than today and the smallest ones melted: strong glacial expansion took place only after 5000 14c years bp. during the same period the calderone glacier melted, leaving the apennines without glaciers. the same glacier, lying at both a lower altitude and latitude than other mountain glaciers, reappeared only in a period more recent than 3895±65 14c years bp, when ela went down to a height lower than the gran sasso peak. grove (1997), in a paper on the holocene european glacial phases, reports glacial advances in the alps ca. 3000-3600, 2100-2600 14c years bp, 800900 ad, and much glacial expansion since 1350 ad. these glacial expansions can be correlated with the calderone stadials 1, 2, 3a, 3b, 3c. in particular, about the italian alps, orombelli & pelfini (1985) report an advance of the forni glacier (ortles-cevedale massif) older than peat dated 2670±130 14c years bp, which can be correlated to the calderone stadial 1. in the pisgana glacier (adamello massif) a glacial expansion took place between 3015±75 and 2345±125 14c bp (baroni & carton, 1991) coincident with the calderone stadial 2. the brenva glacier (mt. bianco massif) advanced (orombelli & porter,1982) and the moraines covered a tree dated 1170±75 14c years bp (760÷980 cal. ad); strumia (1997) found some soil dated 1185±80 14c years bp (734÷980 cal. ad), buried because of the advance of the lys glacier (mt. rosa massif). these glacial advances can be correlated with the calderone stadial 3a. in the alps, starting from the xv century, i.e. during the little ice age, a great deal of glacier expansions took place (for a synthesis see baroni, 2000) which can be coeval, on the whole, to the apennine calderone stadial 3b,3c. 43middle pleistocene to ... ccoonncclluussiioonnss in the apennines the main phases of glacial expansion occurred in the middle pleistocene (probably during the marine isotopic stage 6 or 8) and in the late pleistocene lgm. the middle pleistocene glaciers were 5-10% larger that the upper pleistocene ones during lgm, some glaciers reached an altitude of 700-800 m a.s.l.. the ela value was between 1250 and 1900 m a.s.l., changing according to the altitude, latitude, exposition of the glacial valleys, amount of snow precipitation etc., and according to the distribution of land and seas as pointed out by messerli (1967) for the mountains surrounding the mediterranean sea. ela varied between 1250 and 1550 m, 1550 and 1900, 1600 and 1800 in the northern, central and southern apennines. messerli (1967;1980) calculated the present day snow limits in the northern (ca. 3000 m 44 c. giraudi fig. 3 glacial stadials and equilibrium line altitude (ela) variations from last glacial maximum to the early holocene. the data from the northern apennines stadial ela’s are based on val parma glaciers facing north (from jaurand, 1994, 1998). maximum and minimum ela values reported for the central and southern apennines depend on the different massifs and valley orientations. in the southern apennines, the glaciers melted earlier than in the northern apennines despite the maximum elevation being higher. in the northern apennines the ela is clearly lower than in the central apennines, while there is only a small difference between the central and southern apennines. a.s.l), central (ca. 3220 m a.s.l), and southern apennine (ca. 3330 m a.s.l). as well as during the lgm, the difference between northern and central apennine is bigger than between the central and southern apennine. the moraines are preserved better in the calcareous central and southern apennines than in the northern, formed mainly by marly and arenaceous sediments. in spite of the different data-base, a comparison between the sectors of the apennines chain can be made. in the central apennines, reaching the maximum altitude, the glaciers lasted until the early holocene (fig. 3); later they disappeared but the calderone glacier reappeared and reached its maximum neoglacial length during the little ice age; the same glacier, although very small and completely covered by debris, lies in a portion of the gran sasso high cirque even today. during lgm, the northern apennines ela was lower than in the central and southern sectors. in spite of the elevation of the mountains, in the southern apennines the glacier melted earlier (about 15,000 14c years bp) than in the northern part, where glaciers disappeared about 13,000 14c years bp (fig. 3). according to the published datings, the apennine late pleistocene and holocene glacial advances and retreats were nearly synchronous with the alpine ones: the clearest difference is represented by the early beginning of the lgm apennine glaciers retreat, which started about 21,000 14c years bp. aakknnoowwlleeddggeemmeennttss the present work has been carried out with the financial support of the italian ministry for environment in the frame of the “accordo di programma enea – ministero per l’ambiente”, project 2.4 – climate variations. 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(1982) lembo morenico presso arquata del tronto. bollettino società geologica italiana, 110011 (2), 211-218. trevisan l., dallan l., federici p.r. (1971) note illustrative della carta geologica d'italia alla scala 1:100.000, foglio 96, massa. roma. servizio geologico d'italia, 57 p. 48 c. giraudi impaginato atti tthhee tt’’oorraa ggeeoossooll((??)) ((mmaaiinn eetthhiiooppiiaann rriifftt,, eetthhiiooppiiaa)):: pprroobblleemmss iinn ddeeffiinniinngg ppaallaaeeoossoollss ss.. ccaarrnniicceellllii**,, mm.. bbeennvveennuuttii11,, ff.. bboonnaaiiuuttii,, cc.. iiaassiioo,, dd.. ssaaggrrii,, aa.. mmiirraabbeellllaa22,, mm.. ssaaggrrii11,, gg..aa.. ffeerrrraarrii,, gg.. bbeelllluuoommiinnii33 && uu.. wwoollff *corresponding author, tel. +39 055 3288398, fax +39 055 333273, e-mail carnic@iges.fi.cnr.it 1dipartimento di scienze della terra, firenze, italy 2istituto sperimentale per lo studio e la difesa del suolo, mipaf, firenze, italy 3istituto tecnologie applicate ai beni culturali, c.n.r., roma, italy summary the lake region (main ethiopian rift, mer), is object of major palaeoenvironmental research since the seventies. an integrated soil and late quaternary stratigraphy study in this area revealed the presence, across a wide range of present soil-forming factors, of a group of soils sharing major common features, including: intense smectite neoformation from clay-free parent materials a strongly developed petrocalcic horizon a fairly uniform tephra addition, making them pedocomplexes with two well defined compartments in the mer lower elevation areas, these soils, found on lake ziway terrace v, are incompatible with the present semiarid climate. a major pedogenetical hiatus separates them from those developed on the next oldest terrace, iv, last flooded about 5 14c ky bp. these soils were chronologically placed with respect to the known palaeoclimatic history of the mer, with the help of a newly described and dated stratigraphic section. there is multiple evidence that they developed during the holocene climatic optimum, between 10 and 5 c14 ky bp, when proxy records show for the area a climate moister than present. the wide spread of these soils, their easy field recognition and the importance of early holocene in the palaeoenvironmental history of the mer prompted their use as a key level. as such, they showed to be extremely useful in the interpretation of the geomorphic and sedimentary evolution of the lake region. specifically, they were used in reconstructing phases of landscape stability and instability throughout terminal pleistocene and holocene. such importance and usefulness suggested their possible establishment as a pedostratigraphic unit, a geosol, giving birth to the t’ora geosol definition. however, according to current standards, existing or in discussion, basic problems exist. the t’ora geosol cannot yet be formalized as, in its present reference stratigraphy, it is not buried. a suitable stratotype has been located but not yet described. furthermore, the t’ora geosol is mostly relic, and rarely exhumed, in its surface occurrences. according to the present version of the inqua palaeopedology glossary, the t’ora geosol cannot be defined a palaeosol, as it formed in holocene. consensus palaeoclimatic and chronological frameworks for many tropical areas, however, consider holocene climatic variations to be of a similar order of magnitude of those registered throughout late pleistocene. it appears then rather arbitrary, at least for intertropical areas, to limit the palaeosol concept to the pleistocene when, as shown by our findings, holocene soils may be as useful, or more useful, than older soils in palaeoenvironmental reconstructions. riassunto la regione dei laghi (main ethiopian rift, mer), è oggetto di ricerche paleoambientali dagli anni settanta. un rilevamento integrato dei suoli e dei depositi del tardo quaternario dell’area ha mostrato la presenza di un gruppo caratteristico di suoli definiti da alcuni caratteri principali, comprendenti: estesa neoformazione di smectite da un parent material privo di fillosilicati un orizzonte petrocalcico fortemente sviluppato una deposizione generalizzata di tephra, che li rende dei pedocomplessi con due membri ben definiti alle quote più basse della mer questi suoli, trovati ad esempio sul v terrazzo del lago ziway, non sono compatibili con il clima attuale, semiarido. un forte divergenza di processi genetici li separa dai suoli del terrazzo immediatamente più recente, il iv, la cui età potrebbe raggiungere i 5000 anni 14c bp. questi suoli sono stati collocati cronologicamente, rispetto alla storia quaternaria nota della mer, con l’aiuto di una sezione statigrafica di nuova descrizione, corredata da datazioni. evidenze multiple consentono di datarne la formazione tra 10000 e 5000 anni 14c bp, durante l’optimum climatico olocenico, per il quale i proxy record esistenti suggeriscono un clima più umido dell’attuale. l’ampia diffusione di questi suoli, il loro facile riconoscimento in campagna e l’importanza dell’olocene inferiore nell’area hanno suggeil quaternario italian journal of quaternary sciences 1155(1), 2002, 105-110 iinnttrroodduuccttiioonn the lake region (main ethiopian rift, mer, fig. 1), is characterized by recent intense tectonic and volcanic activity, and marked climate changes. the presence of an endoreic lacustrine system made the area highly suitable for palaeoclimatic reconstructions based on lake levels. the first comprehensive reconstruction of holocene lakes level fluctuations is due to street (1979), also basing on previous work by haynes and haas (1974), geze (1975) and laury and albritton (1974, 1975). chronology was refined by gillespie et al (1983), while more details and a general revision were presented by alessio et al. (1996). the present state of knowledge is summarized in the diagram of fig. 2. the most conspicuous features are the rapid oscillations of the first half of holocene, when lake levels were often much higher then present. the last, and major, high stand occurred about 5 14c ky bp, after which a general declining trend set in. an outstanding finding of an integrated soil survey and late quaternary evolution study in this area was the presence, over a wide range of parent materials, morphological positions and present climates, of a group of soils sharing major common features. provisionally and informally, these soils are defined as the t’ora soil type. the placement of this soil type within current concepts of palaeosol definition presents unusual problems and a sort of a challenge to presently used or proposed definitions, and is the main subject of this paper. aarreeaa ggeeooggrraapphhyy aanndd mmeetthhooddss the mer floor, in the lake region, has a typical elevation of around 1.600-1.700 m a.s.l., but is not uniformly flat; the alutu volcano rises for about 700 m, while the gademota ridge, remnant of a large caldera 106 s. carnicelli et al. rito il loro uso come livello guida. come tale, essi si sono mostrati di grande utilità nell’interpretazione dell’evoluzione stratigrafica e geomorfica della regione dei laghi, e in particolare nella ricostruzione delle fasi di stabilità e instabilità geomorfica attraverso il pleistocene terminale e l’olocene. una tale utilità suggerisce il loro uso come unità pedostratigrafica, un geosol, dando luogo alla definizione del t’ora geosol. tuttavia, gli standard correnti, o in discussione, pongono dei problemi di fondo. il t’ora geosol non può, al momento, essere formalizzato poichè, nella attuale stratigrafia di riferimento, non è sepolto. in ogni caso, questo suolo è assai più frequente ed utile in forma relitta che non sepolta. in base alla versione attualmente in circolazione del glossario inqua di paleopedologia, il t’ora geosol non può essere definito un paleosuolo, essendo datato all’olocene. tuttavia, le ricostruzioni paleoclimatiche generalmente accettate per le aree tropicali evidenziano variazioni climatiche, durante l’olocene, dello stesso ordine di grandezza registrato in generale attraverso il tardo pleistocene. sembra quindi piuttosto arbitrario, almeno per le aree tropicali, limitare il concetto di paleosuolo all’olocene quando, come dimostrato dai nostri risultati, suoli olocenici possono avere altrettanto o più valore dei suoli pleistocenici per le ricostruzioni paleoambientali. key-words: palaeosols, holocene, palaeoenvironment reconstruction, main ethiopian rift, ethiopia parole chiave: paleosuoli, olocene, ricostruzione paleoambientale, main ethiopian rift, etiopia fig. 1 location map and general geographical features of the area 107the t’ora geosol ... (1978) studied a transect of soils across five lacustrine terraces. these had been identified by laury and albritton (1975) and street (1979) to the west of lake ziway, and numbered i to v from the lowest to the highest. verheye (1978) noted the very strong contrast between the soils on terraces i-iv, relatively little differentiated among themselves, and the starkly more evolved soil on terrace v. according to absolute datings by laury and albritton (1975), terrace i-iv are of holocene age, iv having been last flooded during the 5 14c ky bp high stand, while terrace v is considered (street, 1979) of generic pleistocene age. the main contrast was given by the limited weathering of glassy materials, still dominating soil fabric in terraces i-iv, and the huge amount of pedogenic clays formed within the soil of terrace v. very large forms of catastrophic erosion, like gullies and badlands, are prominent throughout the area, representing a major threat to natural resources and local economy. these landforms are nor completely neither easily understood, and are a primary subject of ongoing work. the whole area was mapped according to land system principles, basing on both aerial photographs and landsat tm images. extensive, integrated, field surveys were led during 4 years for geology, soils and land cover/use. soil survey, in particular, entailed description of 106 complete soil profiles, more than half of which were analysed. geological sections through late quaternary deposits were described, suitable materials being dated by both radiometric and ams 14c techniques. in this paper, anyway, only those stratigraphic aspects relevant to the t’ora soil type are considered. rreessuullttss the t’ora soil (fig. 3, table 1) is essentially a relic soil. buried exposures are few and not yet completely studied. its most relevant common properties are: neoformation of large amounts of smectites from parent materials dominated by volcanic glass and essentially clay-free. presence of a strongly developed petrocalcic horizon, normally found below 150 cm and always below 100 cm. presence of a fairly uniform recent tephra addition, making them pedocomplexes (morrison, 1977) with two clearly identifiable soils. the upper soil of the pedocomplex, t’ora a, developed from the recent tephra; it is quite homogeneous in texture and weathering degree, as evaluated from clay mineralogy, strongly suggesting that the recent tephra represents a single volcanic phase in a narrow time interval. the recent tephra then gives to the t’ora soil a unique chronological significance, in the sense that the lower soil must have been the surface soil in a specific moment of time. unfortunately, the recent tephra is too weathered for direct dating by irsl or fig. 2 holocene oscillations of mer lakes levels according to gillespie et al. (1983). sd indicates shala datum, i.e. level of lake shala as surveyed by street (1979); roman numerals indicate ziway-shala lacustrine phases. (laury & albritton, 1975), forms an arc structure 20 km in diameter, rising up to 400 m above the plain. west of the gademota relief an extended flat ridge, about 5 km wide, stretches nne-ssw for 80 km, rising up to 2.000 m a.s.l. it is formed by a series of uplifted and/or tilted blocks, making up an horst system that separates the main mer floor from the rift-in-rift depression of the abay-golel’sha lakes. the area can then be divided in two main physiographic sections: the horst system and the mer bottom. this last is rather dry: at ziway, average annual rainfall is around 700 mm, temperature 18°c and temperature regime isothermic; areas around lakes abiyata and langano are probably drier. in the horst system, yearly rainfall varies instead between 900 and 1000 mm, and temperatures are somewhat lower. huge volumes of pyroclastic materials, mainly peralkaline rhyolitic ignimbrites, extend on most of the mer (woldegabriel et al., 1990). in the valley bottom they are covered by fluvio-lacustrine sediments, whose terrigenous component is dominated by pyroclastic materials. these sediments were laid down in a very wide lake which, in some late pleistocene intervals and again in early holocene, occupied most of the mer floor (street, 1979); the four present-day lakes are the remnants of that ancient lacustrine basin. the lake region is crossed by two belts of recent tectonic deformation, trending ssw-nne: the siltidebre zeit fault zone (sdzfz) to the west and the wonji fault belt (wfb) to the east (di paola, 1972; woldegabriel et al., 1990). these belts consist of hundreds of steep normal faults, forming grabens, half-grabens and fault-bounded blocks. the sdzfz is 5-10 km wide and 80 km long, with very recent basalt effusions, dated 0.13 myr to present (woldegabriel et al., 1990). in a previous pedological investigation, verheye similar techniques. basically, t’ora a soil is characterized by a mollic horizon, whose thickness varies significantly in agreement with morphological position, as a result of some redistribution by slope processes. profiles observed in the western part of the area often show a moderately thick argic horizon. consequently, the upper soil is either an haplic, a pachi-haplic or a luvic phaeozem. a striking field reconnaissance feature is the c horizon. pale grey in colour and slightly cemented by silica, this horizon protrudes in natural sections, where it clearly stands out. the clay fraction of the t’ora a soil is characterized by poorly ordered smectites, representing the weathering product of the ashy materials; kaolinite is also present, as a weathering product of the sanidine component of the parent material. clay content is below 30%, so that smectites do not express themselves in vertic characters, hampered by the very different physical behaviour of the less weathered ashes. the lower soil of the pedocomplex, t’ora b, developed from a great variety of parent materials: saprolite from the rift floor ignimbrites; slope and alluvial fan deposits flanking the major relief reworked pyroclastics of the gademota formation (laury and albritton, 1975, the t’ora soil is at the top) the lacustrine deposits of ziway lake terrace v (verheye, 1978) air-fall tephras over terrace v, related to the abernosa pumice member of street (1979). notwithstanding this variety, the t’ora b soil has fairly homogeneous characters. it has a very thick argic horizon, homogeneous in clayey texture and mineralogy but vertically differentiated in other characters. the upper subhorizon (2btb1) is black, with medium to coarse prismatic structure, cracks and thick clay coatings; it is subacid. underlying subhorizons (2btb, 2bc) are reddish brown (7.5 yr), with fine angular blocky structure, plentiful pressure faces and thin, though continuous, clay coatings; they are often subalkaline, with esp between 6 and 14. main lateral variations concern total thickness, vertic features and petrocalcic horizon expression. thickness is mostly linked to parent material, the deepest sola being found on slope deposits. vertic features appear in the lower part of the btb1, and are associated with morphological position in a complex way. they are typical and strongly expressed, with sphenoid structure, in the largest depressions to the east of the horst hills; they are not normally found, instead, in the local grabens inside the horst system. the local grabens actually have more relief energy than the larger depressions, and presently experience more dramatic shifts in hydrological conditions. morphology of the petrocalcic horizon is linked to parent material, but in the south-western area, the moister one, this horizon grades into a calcic with large, hard concretions. calcic and petrocalcic horizons are not found in any other soil of the surveyed area. t’ora b soil classifies as a hyposodic vertic or profondic hyposodic luvisol. use of the soil taxonomy allows sometimes to express the petrocalcic horizon, and some pedons classify as petrocalcic paleustalf, but most sort out as typic paleustalf; vertic subgroups cannot be defined in buried soils according to the soil taxonomy. cchhrroonnoollooggyy in the mer bottom, the t’ora soil is incompatible with the present semiarid climate. in this area, it is found on terrace v of lake ziway; a major pedogenetical hiatus, first described by verheye (1978), and confirmed by our survey, separates it from soils on the lower terraces, represented by phaeozems or cambisols. chronological placing of the t’ora soil is presently based on multiple stratigraphical, geomorphological and palaeoclimatic evidence. a stratigraphic section in the colluvial apron of the gademota ridge (fig. 4) clarified several ambiguities. lacustrine sediments dated 30 14c ky bp mark, given their elevation, the most recent known date for flooding of lake ziway terrace v, but a successive and higher, as yet undated, lacustrine phase appears. the t’ora soils on terrace v cannot then have 108 s. carnicelli et al. fig. 3 a t’ora soil profile; in this particular observation, the upper soil of the pedocomplex is a stable phase (luvic phaeozem); the lower soil shows some vertic features (slickensides), just to right of letter b). a) upper soil; b) lower soil; c) petrocalcic horizon 109 started developing before 30 14c ky bp, and possibly much later. age of lake ziway terrace iv is well known (laury and albritton, 1975; street, 1979; gillespie et al., 1983); it was last flooded about 5 14c ky bp. in the gademota section, the t’ora soils are found on top of the oldest vertical sequence of sediments, and presently at the surface. two strong erosional unconformities follow; deposits above the second unconformity were dated about 4600 14c y bp. on the surface represented by the top of the deposits between the two unconformities, a well developed luvisol is visible. it is clearly differentiated with respect to the t’ora soil, as it lacks both the petrocalcic horizon and the tephra addition. the same luvisol is found directly burying the whole t’ora soil pedocomplex in another section in the abay basin, to the west; this section is presently only dated and studied for the very recent part. soils above the second unconformity in the gademota section are never more developed than cambisols or phaeozems. in all other cases, when the t’ora soil is found over dated deposits, these are always known to be of pleistocene, and never of holocene, age. there is then multiple evidence that the t’ora soil developed on the geomorphic surfaces existing after the very aggressive erosional phase corresponding with the last glacial maximum and the terminal pleistocene, when climate in this area is known to have been semidesertic (gasse and street, 1978). this is supported by the evidence that t’ora soil formed over very extensive, complex colluvial and alluvial fan buildings around the major relief. the t’ora soil is then presently understood to have formed during the holocene climatic optimum, between 10 and 5 ky bp, when climate in the area is known to have been quite moister than present. ssttrraattiiggrraapphhiicc aanndd ppaallaaeeooeennvviirroonnmmeennttaall ssiiggnniiffiiccaannccee the wide spread of the t’ora soil, its easy field recognition and the importance of early holocene in the palaeoenvironmental history of the area prompted its use as a key level. as such, the t’ora soil was extremely useful in the interpretation of the geomorphic evolution and of undated sedimentary successions in the lake region. specifically, it was of great help in reconstructing phases of landscape stability and instability throughout late pleistocene and holocene. there are several reasons to interpret variations in t’ora b as expressions of a limited amount of lateral, sin-pedogenetic (“pedofacies”), differentiation. vertic features expression resemble a catenary sequence, weak and inconsistent with respect to present relief. inconsistency is reconciled by reconstructions of recent tectonic activity, according to which relief, in the horst system, has been enhanced in late holocene by dislocations along riftwise fault swarms. slope processes taking place in consequence of this relief rejuvenation are instead well marked in the lateral differentiation of t’ora a, the present surface soil in this phase. t’ora a can clearly be divided in stable (argic phaeozems), eroded (haplic phaeozems) and cumulic (pachi-haplic phaeozems) phases, perfectly consistent with present slopes in the horst system. expression of the petrocalcic horizon varies consistently with the modern rainfall gradient. in the mer such gradients, however, are controlled by the orographic influence of the main escarpments, and their geographic structure should not have varied greatly during the late quaternary, except for changes in absothe t’ora geosol ... fig. 4 summary of the gademota north stratigraphic section, with datings lute rainfall values and intensity of the gradient itself. the present distribution of the t’ora soils leads, in fact, to suspect that, in moister holocene intervals, the gradient ought have been less intense than at present. this is suggested by the very limited differences between t’ora soil occurrences in the presently dry mer bottom and in the presently moister horst hills. the early holocene increase in rainfall appears then to have been greater in the central than in the side portions of the mer bottom. such kind of differentiation of early holocene from modern climate is also expressed by the huge pedogenetic hiatus separating the t’ora soil from soils on ziway terrace iv, while a much lesser hiatus is evident in the presently moister areas. matching the occurrence of the t’ora soil with observed landforms, clear phases can be distinguished in the geomorphic evolution of the area. the late pleistocene was marked by the build-up of massive colluvial aprons and alluvial fans, smoothing the links between high-lying and depressed areas. these surfaces, covered by the t’ora soil, have undergone a complex holocene evolution. most colluvial aprons underwent multiple cycles of incision and filling up of large, gully-like channels. alluvial fans apparently remained quite stable until recent times, when, in most cases, the build-up of an upper storey, burying the t’ora soil surface, is observed. recent tectonic activity in the horst system has instead consistently brought about the partial destruction of the t’ora soil surface and the build-up of complex response colluvial aprons at the base of the escarpments. ddiissccuussssiioonn the use that could be made of the t’ora soil in studying the late quaternary history of the area would suggest its definition as a pedostratigraphic unit, a geosol (morrison, 1977), giving birth to the t’ora geosol definition. however, checking definitions with current, existing or in discussion, standards revealed basic problems. according to nacsn (1983), the t’ora geosol cannot presently be formalized as, in its present reference stratigraphy (the gademota section), it is not buried. a suitable stratotype (the abay section) has been located but not yet fully described and dated. however, the t’ora geosol is mostly relic, and rarely exhumed, in its surface occurrences, so it is questionable whether it would satisfy the nacsn requirements even after description of an adequate stratotype. according to the present draft of the inqua palaeopedology glossary, the t’ora soil cannot be defined a palaeosol, because it formed in holocene. the consensus palaeoclimatic and chronological framework for this area, as for many other tropical areas, considers the holocene as far from a homogeneous period. it is agreed that climatic variations during the last 10k years are of a similar order of magnitude to those registered throughout late pleistocene, with the only exception of the glacial maximums. it appears then rather unsatisfactory, at least for intertropical areas, to limit the palaeosol concept to the pleistocene when, as shown by our findings, holocene soils may be as useful, or more useful, than older soils in palaeoenvironmental reconstructions. generally speaking, excess formalism in definitions appears disadvantageous in a field like quaternary sciences, where totally new findings and paradigm upset are the order of the day. aacckknnoowwlleeddggeemmeennttss this work was funded by italian ministry for university and scientific research, under prin 1999 “risposta geomorfica ai cambiamenti ambientali in aree ad alta crescita demografica (rift etiopico)”. rreeffeerreenncceess alessio, m., allegri, l., belluomini, g., benvenuti, m., cerasoli m., improta, s., manfra, l., sagri, m. and ventra, d. (1996). le oscillazioni tardo-quaternarie del lago shala (rift etiopico): analisi dell'evoluzione ambientale dall'integrazione di evidenze morfologiche, sedimentarie e cronologiche. il quaternario, 9, 387-392. di paola, g.m. (1972). the ethiopian rift valley (between 7° 00' and 8°40' lat. north). bull. vulcanol., 36, 517-560. gasse, f. and street, f.a. (1978). late quaternary lake-level fluctuations and environments of the northern rift valley and afar region (ethiopia and djibouti). pal., pal., pal., 24, 279-325. geze, f. (1975). new dates on ancient galla lake levels. bull. geophys. obs. addis ababa 15, 119-124. gillespie, r., street-perrot, a.f. and switsur, r. (1983). post-glacial arid episodes in ethiopia have implications for climate prediction. nature, 306, 680-683. haines, v. and haas, h. (1974). southern methodist university radiocarbon date list. radiocarbon, 16, 368-380. laury, r.l. and albritton, c.c. (1974). geology. in: wendorf, f. and schild r. (eds.): a middle stone age sequence from the central rift valley, ethiopia. polish acad. sci., warsaw, 252 pp. laury, r.l. and albritton, c.c. (1975). geology of the middle stone age archaeological sites in the main ethiopian rift valley. geol. soc. am. bull., 86, 999-1011. morrison, r.b. (1977). quaternary soil stratigraphy, concepts, methods and problems. in: mahaney, w.c. (ed.): quaternary soils, pp. 77-108. geoabstracts, norwich. north american commission on stratigraphic nomenclature (nacsn) (1983). north american stratigraphic code: american assoc. petroleum geologists bull. 67, 5, 841-875. street, f.a. (1979). late quaternary lakes in the ziwayshala basin, southern ethiopia. unpublished ph.d. thesis, univ. cambridge, 457 pp. verheye, w. (1978). soils and soil evolution on the holocene lacustrine terraces of lake zway, rift valley, ethiopia. pedologie, 28, 21-45. woldegabriel, g., aronson, j and walter, r.c. (1990). geology, geochronology and rift basin development in the central sector of the main ethiopian rift. geol. soc. am. bull., 102, 439-458. 110 s. carnicelli et al. ms. ricevuto marzo 2002 ms. received: march 2002 imp. esposito llaattee qquuaatteerrnnaarryy sshhoorreelliinneess iinn ssoouutthheerrnn cciilleennttoo ((mmtt.. bbuullgghheerriiaa)):: mmoorrpphhoossttrraattiiggrraapphhyy aanndd cchhrroonnoollooggyy ccaarrmmeellaa eessppoossiittoo11,, ffrraanncceessccaa ffiillooccaammoo11,, rroobbeerrttaa mmaarrcciiaannoo11,, ppaaoollaa rroommaannoo11,, nniiccoolleettttaa ssaannttaannggeelloo11,, ffaabbiioo ssccaarrcciigglliiaa22 && ppaaoollaa ttuucccciimmeeii33 1dipartimento scienze della terra università di napoli federico ii 2dipartimento scienze della terra università della calabria 3dipartimento di geologia università di roma tre abstract a detailed geological and geomorphological survey of shorelines and continental deposits, cropping out along the carbonate coast between the mingardo river mouth and cala degli infreschi bay, was carried out. several erosional indicators of paleo-sea level stands were collected such as notches, wave-cut terraces and upper limits of lithophaga burrows. littoral sediments are often present on with these erosional features and are made up of sands and conglomerates which locally contain mollusc shells, red algae and corals. these evidence have been preserved along paleo-sea cliffs or inside coastal caves of prevalent karstic origin. the continental deposits, often associated with marine successions, are represented by eolian and colluvial deposits, paleosols and, inside the coastal caves, by speleothems and graviclastic breccias. in many localities these continental deposits contain lithic industries of palaeolithic age which can be considered as lower or upper chronological limits for the associated shorelines. geomorphological cut-cross relations, stratigraphic position and altimetrical correlation among continental and marine deposits were analysed in order to recognise both their relative chronology and the phases of coastal morphogenesis, linked to the interaction between sea level fluctuations and tectonic uplift. mineralogic analysis on paleosols was also carried out for paleoenvironmental reconstructions. moreover, th/u datings of speleothems, which directly cover or are buried by marine deposits, were carried out in order to give chronological constrains for the reconstruction. at least six orders of middle pleistocene marine terraces are present between 75 and 15 m a.s.l.; the complete flight of these terraces is only well preserved along the western part of the mt. bulgheria coast. between 10 e 3.5 m a.s.l. we recognised three other paleo-sea level stands, the youngest of which is represented by fossiliferous conglomerates and sands. the th/u age of the speleothem (90 ka bp) which is buried by these marine deposits and the th/u age of the speleothem which cover the marine sands (50 ka bp) allowed us to ascribe this shoreline to the oiss 5a. this correlation is supported by the mousterian age of the graviclastic breccia lying on them. riassunto e’ stato eseguito un rilevamento geologico e geomorfologico di dettaglio delle linee di riva e dei depositi continentali affioranti lungo il settore di costa carbonatica compreso tra la foce del fiume mingardo e cala degli infreschi. sono stati individuati diversi indicatori erosionali di paleostazionamenti del livello marino, rappresentati da solchi bioerosivi, piattaforme d’abrasione e dal limite superiore orizzontale dei fori di litodomi. spesso a queste forme erosionali si associano depositi marini, costituiti da sabbie e puddinghe che localmente contengono resti di molluschi, alghe rosse e coralli. queste evidenze sono preservate lungo le paleofalesie o all’interno di grotte costiere, in molti casi di origine carsica. depositi continentali sono a volte associati alle successioni marine; si tratta soprattutto di depositi eolici, colluvioni, paleosuoli e, all’interno delle grotte, di speleotemi e brecce graviclastiche. in molte località questi depositi contengono industrie paleolitiche che possono essere considerate come limite cronologico inferiore o superiore per le linee di riva ad esse associate. l’analisi dei rapporti geomorfologici, le posizioni stratigrafiche e la correlazione altimetrica tra i depositi continentali e marini hanno permesso di ricostruire la loro cronologia relativa e le fasi di morfogenesi costiera legate all’interazione tra le variazioni del livello marino e i movimenti di sollevamento. analisi mineralogiche sono state condotte sui paleosuoli allo scopo di ottenere delle ricostruzioni paleoambientali. inoltre, sono state eseguite datazioni th/u di alcuni speleotemi che poggiano su/ o sono coperti da depositi marini, al fine di ottenere dei vincoli cronologici per la ricostruzione degli eventi. tra 75 e 15 m s.l.m. sono stati riconosciuti almeno sei ordini di terrazzi marini medioplestocenici; questa gradinata di terrazzi si è preservata completamente solo lungo il settore costiero occidentale del monte bulgheria. tra 10 e 3.5 m s.l.m. sono presenti altri tre paleostazionamenti marini, il più recente dei quali è rappresentato da una puddinga fossilifera che passa verso l’alto a sabbie. l’età th/u dello speleotema (90 ka bp) su cui si rinvengono i suddetti depositi marini e quella dello speleotema che copre le sabbie (50 ka bp) permettono di ascrivere questa linea di riva al substage 5a della stratigrafia isotopica. tale attribuzione è confermata dall’età mousteriana delle brecce graviclastiche poggianti sul deposito marino. keywords: paleo-sea level stands, late quaternary, speleothem, paleosol, u-series dating, cilento promontory, southern italy. parole chiave: paleostazionamenti del livello marino, tardo quaternario, speleotema, paleosuolo, datazioni con la serie dell’uranio, cilento, italia meridionale. il quaternario italian journal of quaternary sciences 1166(1), 2003, 3-14 11 iinnttrroodduuccttiioonn the cilento promontory is a large structural high located between the gulf of salerno to the north and the policastro gulf to the south (fig.1). its southern coasts are carved in high resistant rocks such as limestones and cherty limestones (flintstones) of the mt. bulgheria mesozoic– caenozoic units. due to the pliocenequaternary tectonic history of the mt bulgheria massif, which was characterised by several phases of normal faulting mainly ew and ne sw trending (ascione et al., 1997), the coast of southern cilento is constituted by 4 c. esposito et al. same structure-controlled bays, filled in some cases with sandy and gravelly beaches (capo grosso, cala d’arconte, la calanca and lentiscelle beaches), which alternate with active vertical sea cliffs from some metres to hundreds of metres high. karstic caves, more or less reworked and enlarged by marine abrasion (esposito et al., 2001), are present all along the carbonate active and inactive sea cliffs. the slope developing over the sea cliff is characterised by a flight of marine terraces, from 400 to10 m above the present sea level, cut by subsequent and consequent stream valleys. according to the last researches carried out on the marine terraces of southern cilento (ascione & romano, 1999; russo, 1994), the eutyrrhenian shoreline (i.e. the one correlated with the oxygen isotope substage 5e) can be found at almost the same elevation along the coast of mt. bulgheria; i.e. it was recognised at cala bianca bay at 6 m a.s.l. by means of racemization on astralium shells (russo, 1994). these findings testifie a late quaternary tectonic stability for the area. moving southward of the mt. bulgheria coasts, a moderate upper pleistocene-holocene tectonic uplift was highlighted near sapri, where brancaccio et al. (1990) recognised, at 15 m a.s.l., fossiliferous marine conglomerates dated to the eutyrrhenian transgression. finally, evidence of post-eutyrrhenian subsidence was pointed out at capo palinuro, the carbonate promontory that bounds mt. bulgheria to the north, where a + 2 m high marine notch was correlated to the oiss 5e sea level highstand (antonioli et al., 1994). in this paper the results of a detailed survey carried out on the late quaternary shorelines along the coast of mt. bulgheria are presented. the collected data refer to all the erosional and depositional indicators of fossil shorelines which are preserved along the active and inactive sea cliffs as well as inside the coastal caves. as erosional indicators we considered the point of maximum concavity of bioerosive notches (sensu pirazzoli, 1996), the inner rim of wave-cut terraces and the upper limit of burrows (the latter only when straight, horizontal and laterally continuous for some metres). along the fossil shorelines, a detailed survey was also carried out on the continental deposits associated with the erosional and depositional marks of strandlines, such as alluvial and colluvial deposits, paleosols, tephra layers and speleothems. 22 ggeeoollooggiiccaall aanndd ggeeoommoorrpphhoollooggiiccaall sseettttiinngg ooff tthhee ssoouutthheerrnn cciilleennttoo starting from the sixties, several geological, structural and geomorphological studies have been carried out in order to reconstruct the mt. bulgheria long and short term geological history (scandone et al., 1964; ciampo, 1976; lippmann-provansal, 1987; borrelli et al., 1988; tozzi et al., 1996; ascione a., 1997; ascione et al., 1997; ascione & romano, 1999). the massif is a topographic high made up of a carbonate succession upper triassic to lower miocene in age which is unconformably covered by pliocenequaternary continental, transitional and marine deposits. the pliocene-quaternary geomorphological and tectonic evolution of mt. bulgheria is testified by fluvial and lacustrine terraces, wave-cut and wave-built marine terraces, structure controlled forms (such as fault scarps, subsequent fluvial valleys, etc.), as well as by the above quoted successions of different sedimentary environments. in particular, the early pleistocene depositional events were recorded by marine successions: the s. vito formation, santernian in age (ascione, 1997), the lentiscosa formation (sgrosso & ciampo, 1966; lippmann provensal, 1987; borrelli et al., 1988), the cala bianca frms emilian in age (sgrosso & ciampo, 1966; ciampo, 1976) and torre dell’isola frms, emilian in age (ascione, 1997). all these formations are unconformably lying on the caenozoic and mesozoic fig. 1 location of the studied area. ubicazione dell’area studiata. units. nowadays these successions outcrop between 400 and 0 m a.s.l. (fig.2). in same cases these formations are associated with depositional terraces displaced between 450 m and 300 m a.s.l. by subsequent phases of normal faulting. the wave cut terraces located between 450 and 300 m a.s.l. are correlated with the lower pleistocene depositional marine terraces. the flight of erosional and depositional marine terraces located between 150 and 12÷10 m a.s.l., which formed during middle pleistocene, testifies the effect of the final uplift that affected the mt. bulgheria and the last phase of relief growth. moreover, the fact that the terraces develop with continuity along the coastal belt indicate at the same time the cessation of block faulting. according with ascione & romano 1999 during upper pleistoceneholocene, due to the substantial tectonic stability of the area, the coastal morphogenesis mainly proceeds in response to climate oscillations and the consequent glacio-eustatic sea level fluctuations. 5late quaternary shorelines ... 33 ssttrraattiiggrraapphhiiccaall aanndd ggeeoommoorrpphhoollooggiiccaall ddaattaa a detailed geological and geomorphological survey of the coast between t. fenosa and cala degli infreschi, along the southern slope of mt. bulgheria, was carried out. the recognised erosional and depositional evidence of ancient paleo-sea levels were grouped into five main ranges of altitude: 12÷10, 8.5÷8; 7.5÷5, 4.5÷4, 3.5÷3 (fig.2). in the eastern sector of the studied area, in a little circular bay named cala degli infreschi, a well preserved stratigraphical record is present made by both marine and continental deposits. a particular attention was thus focused on this bay. eevviiddeennccee aatt 1122÷÷1100 m a.s.l.– this shoreline is mainly represented by wave-cut terraces (fig.3), continuously present along the coastal sector, cut in both the monte bulgheria mesozoic limestones and the torre fig. 2 geomorphological map of southern sector of mt.bulgheria (salerno-italy) and synthetic table of morphological indicators of paleo-sea levels between 12-10 m and 0 m a.s.l. carta geomorfologica del settore meridionale del mt. bulgheria (salerno, italia) e tabella riassuntiva degli indicatori morfologici di paleolinee di riva tra 12-10 m e 0 m s.l.m. 6 dell’isola conglomerates (emilian stage). the stratigraphical constraints for this order of terraces are well exposed at cala d’arconte and capo grosso bays where two different generations of paleosols, developed on colluvial deposits, cover the wave-cut terraces. the oldest one (2.5÷3 m thick) is reddish, contains manganese nodules and some stonelines; several artifacts of acheulean age were reported by palma di cesnola (1982). the youngest paleosol (6 m thick), discordant on the other, is brownish-red and does not contain gravels; mousterian artifacts were found in it (palma di cesnola, 1982). a lens of grey, weathering pyroclastic sand is present at the top of the youngest paleosol. in the cilento area the mousterian lithic industries are dated between 130 and 40 ka b.p. (gambassini & ronchitelli, 1998). this means that the oldest colluvium, which only contains acheulean artifatcs, was settled before 130 ka b.p.; consequently the age of the 12÷10 m terrace, over which the paleosol is located, is pre-tyrrhenian. another evidence of this shoreline is represented by the inner edge of the wave-cut terrace located at 10 m a.s.l. and covered by marine grey sandstones along the cala d’arconte promontory, and by a bioerosive notch, clearly visible on the right side of grotta della serratura cave, in the cala lentiscelle bay. eevviiddeennccee aatt 88..55÷÷ 88 mm aa..ss..ll.– this shoreline is represented by a wave-cut terrace in the west side of calanca bay, by horizontal upper limits of lithophagous burrows, between monte di luna and cala bianca and in riparo infreschi cave, and by two bioerosive notches in cala bianca bay and in the infreschi cave. eevviiddeennccee bbeettwweeeenn 77..55 aanndd 55 mm aa..ss..ll..between torre fenosa and marina di camerota wave-cut terraces and bioerosive notches, located at 6÷5 m a.s.l., represent the evidence of an ancient shoreline. remains of grey marine sandstones are associated with some of these terraces. on the torre dell’isola promontory a bioerosive notch located at 7.5 m a.s.l. may be the evidence of another paleo-sea level, but no similar evidence was found along the coastal sector. in particular, on this promontory between 7.5 and 5 m a.s.l.. at least three relative paleo-sea levels can be recognised, respectively at + 7.5 , + 5 m. and + 7 m (fig.4). at 5 m a.s.l., in fact, a wave-cut terrace with polygenic well rounded beach conglomerates is present. the conglomerates are unconformably covered by a fossiliferous marine deposit (1.5 m thick), which laterally passes to a clinostratified grey sandstone (2 m thick). the latter is cut at 7 m a.s.l. by a sub--horizontal surface that looks like another wave-cut terrace. a reddish continental deposit covers this terrace and fills the bioerosive c. esposito et al. fig. 3 the10 m a.s.l. wave-cut terrace of cala d’arconte promontory. terrazzo d’abrasione dei 10 m s.l.m. sul promontorio di cala d’arconte. fig. 4 schematic profile of torre dell’isola sector. ca-mesozoic limestone; co1marine monogenic conglomerates and breccias of torre dell’isola succession; co2marine polygenic conglomerates; snmarine sands; cn-continental deposits with breccias and flowstone; n-bioerosive notch lithophaga burrows. profilo schematico del settore di torre dell’isola. cacalcari mesozoici; co1-puddinghe monogeniche e brecce della successione di torre dell’isola; co2puddinghe poligeniche; snsabbie marine; cndepositi continentali con brecce e concrezioni; nsolco bioerosivo; fori di litodomi. 7 notch at 7.5 m a.s.l., too. stratigraphic relations between erosional features and deposits suggest the following relative chronology of events: the + 7.5 m notch represents a first paleosea level stand, the + 5 m wave-cut terrace and the grey marine sandstones indicate a subsequent sea level stand and a relative trasgression, finally the sea level stand rises again, as the + 7 m wave-cut terrace testifies. after this marine phase, the deposition of continental deposit occurs. eevviiddeennccee aatt 44..55--44 mm aa..ss..ll..between torre zancale and cala degli infreschi, bioerosive notches and wavecut terraces are clearly visible at 4.5÷4 m a.s.l.. these erosional morphologies are rather continuous and sometimes remains of grey marine sandstones (similar to the sandstone cropping out on the + 5 m terrace located w of marina di camerota, see precedent paragraph) are visible on the terrace. in the cala bianca and cala degli infreschi bays a cladocora-bearing biocalcarenite is present on the 4.5 m wave-cut terrace. eevviiddeennccee aatt 33..55--33 mm aa..ss..ll.– evidence of this shoreline was mainly observed in the eastern coastal sector and along the western promontory of the calanca bay (fig.5) where a continuous (ca. 200 m) and well-marked wave-cut terrace with marine sandstones (max 2 m thick) is present. 33..11 tthhee ccaassee ooff ccaallaa ddeeggllii iinnffrreesscchhii.. in the sub-circular bay of cala degli infreschi a lot of different erosional indicators of paleo-sea level stands together with marine and continental deposits were collected; the stratigraphical record is well preserved in two little caves located in the western sector of the bay: the infreschi cave and the riparo infreschi cave (fig. 2). tthhee iinnffrreesscchhii ccaavvee this cave represents a remnant of an ancient karstic phreatic level (esposito et al., 2001) connected with the basal water table of mt. bulgheria, that nowadays flows into the sea through karstic channels located along the western rim of the bay. the oldest evidence of a paleo-sea level stand is represented by a well-marked bioerosive notch located at 8 m a.s.l. on the right side of the cave (fig 6, 7a); this notch is cut by a wide strip of lithophaga burrows, whose upper limit is horizontal and located at 8.5 m late quaternary shorelines ... fig. 5 the 3.5 m a.s.l. wave-cut terrace of calanca bay. la piattaforma d’abrasione di 3,5 m s.l.m. della baia della calanca. fig. 6 schematic profile of infreschi cave. ca-mesozoic limestone; co1-marine conglomerates; bcbiolimestonenite with cladocora; co2-marine conglomerates; snmarine sands; brgraviclastic breccias; ps-paleosol; pr-pyroclastic layer; n-bioerosive notch; lithophaga burrows. profilo schematico di grotta degli infreschi. cacalcari mesozoici; co1puddinghe; bcbiolimestonenite a cladocora; co2puddinghe; snsabbie marine; brbrecce graviclastiche; ps-paleosuolo; prpiroclastite; nsolco bioerosivo; fori di litodomi. 8 a.s.l.. at the entrance of the cave a wave-cut terrace is present at 4.5 m a.s.l. (fig.6, 7b) cut in the carbonate succession of mt. bulgheria as well as in a monogenic carbonate beach conglomerate. the external rim of this terrace is covered by a cladocora-bearing biocalcarenite which is also visible in remains on the wall of the cave up to 6 m a.s.l.. this biocalcarenite is covered by a polygenic beach conglomerate (ca.1 m thick) passing upward to plano-parallel stratified sands, clearly trasgressive and unconformable on the cladocora-bearing biocalcarenite; the top of these sands reaches the altitude of 6 m. along the scarp of the + 4.5 m wave-cut terrace a bioerosive notch, located at about 3.5 m a.s.l., is present and continuously well preserved also in the area surrounding the cave. at the back of the cave a continental succession covering the sands is preserved; it is made up of graviclastic carbonate breccias almost without matrix, passing upward to a brownish paleosol with manganese nodules (see p.5). two strongly altered yellowish pyroclastic levels are included in the paleosol. tthhee rriippaarroo iinnffrreesscchhii ccaavvee this site represents the remains of an ancient coastal cave, like that of infreschi, now destroyed by roof c. esposito et al. fig.7 infreschi bay. athe 8 m a.s.l. bioerosive notch; b-the 4 m a.s.l. wave-cut terrace. cala degli infreschi. asolco bioerosivo a quota 8 m s.l.m.; bpiattaforma d’abrasione dei 4 m s.l.m. fig. 8 schematic profile of riparo degli infreschi cave. ca-mesozoic limestone; co1-marine conglomerates; sp1speleothem; lithophaga burrows; brgraviclastic breccias; n-bioerosive notch; co2-marine conglomerates; sn-marine sands; brmmousterian graviclastic breccias; sp2speleothem; pspaleosol; pr-pyroclastic layer. profilo schematico del riparo degli infreschi. cacalcari mesozoici; co1puddinghe; sp1speleotema; fori di litodomi; brbrecce graviclastiche; nsolco bioerosivo; co2puddinghe; snsabbie marine; brmbreccia graviclastica di età musteriana; sp2speleotema; ps-paleosuolo; prpiroclastite. falls. also in this case a well preserved record of marine and continental deposits is present (fig.8, 9). mousterian lithic industries were found in the continental part of the succession (guide archeologiche, 1996). all deposits are preserved on the left side and in the central part of the paleo-cave together with erosional evidence of paleo-sea level stands. in particular, the highest evidence is represented by a wide strip of burrows whose horizontal upper limit rests at 8.5 m a.s.l.. at about 8 m a.s.l., a flowstone drapping the wall of the cave was found, which was cut by the burrows and then sampled for u-series dating (sspp11--rrii 77). at about 6 m a.s.l. carbonate marine conglomerates are covered by a speleothem; as the carbonate substratum, both of them are cut by burrows (fig.10). this speleothem was sampled for u-series dating. (sspp11--rrii 55). over the carbonate marine conglomerates and over the speleothem, marine sands are present, which aa bb 9late quaternary shorelines ... fig. 9 riparo degli infreschi cave. co1marine conglomerates; sp1speleothem; brgraviclastic breccias; co2-marine conglomerates; snmarine sands; sp2speleothem; pspaleosol; prpyroclastic layer; ri 7sample of sp1 at 8 m a.s.l.; ri 5sample of sp1 at 6 m a.s.l.; ri1sample of sp2. riparo degli infreschi. co1puddinghe; sp1speleotema; brbrecce graviclastiche; co2puddinghe; snsabbie marine; sp2speleotema; pspaleosuolo; prpiroclastite; ri 7campione di sp1 a 8 m s.l.m.; ri 5campione di sp1 a 6 m s.l.m.; ri 1campione di sp2. fig. 10 riparo degli infreschi cave. aspeleothem cut by lithophaga burrows; bspeleothems and marine conglomerates cut by litophaga burrows. riparo degli infreschi. aspeleotema tagliato da fori di litodomi; bspeleotemi e puddinghe tagliati dai fori di litodomi. aa bb fig. 11 infreschi cave paleosol. xrd patterns for fine clay (< 0.2 mm) fractions after different treatments in horizon b3. il = illite; k = kaolinite; sm = smectite; d is expressed in nm. palesuolo di grotta degli infreschi. diffrattogrammi ai raggi x delle argille fini (< 0.2 mm) con differenti trattamenti nell’orizzonte b3. il = illite; k = caolinite; sm = smectite; d è espressa in nm. reach 6 m a.s.l. and clearly cover the burrows. these marine sands also cover a bioerosive notch located at 3.5 m a.s.l., which cuts the flank of the cave. the sands pass downward to carbonate marine conglomerates with abundant matrix and gasteropod shells with spines. in the central part of the paleo-cave at 4 m a.s.l., this conglomerate clearly covers a flowstone which is cut by several burrows. this speleothem was also dated using u-series (sspp11--rrii 44) . a graviclastic breccia containing remains of mousterian age is present over the above mentioned conglomerate, testifying human frequenting of the cave at the end of upper pleistocene. over the breccia deposit a pyroclastic level , which passes upward to a brownish paleosol, is preserved in a corner of the paleo cave. this pyroclastic level is strongly weathered and for this reason its petrochemical analysis didn’t give any significant result. further flowstones, laying on the sands and on the breccia deposits and never cut by burrows lithophaga, were sampled (sspp22--rrii 11) in order to give upper chronological constraints to the reconstruction. 44 uu--sseerriieess ddaattaa four speleothems interbedded with marine deposits were sampled in riparo infreschi cave and analysed by u-series disequilibria. samples were accurately fieldselected in order to exclude all materials with macroscopic signs of weathering and further examined under a binocular microscope to refine the selection. fragments with no trace of secondary alteration were analysed according to standard procedures (bischoff et al., 1988). three to six gram samples were spiked with a 228th + 232u tracer (in secular equilibrium) and activity ratios were counted in an eg&g ortec 920-8 alpha spectrometer system. the ages and the initial 234u/238u activity ratios were calculated by means of isoplot, a plotting and regression program designed by ludwig (1994) for radiogenic-isotope data. the uranium contents, the activity ratios and the calculated 230th ages are listed in tab.1; all errors are reported as 1 sigma. coral samples from infreschi cave in cala degli infreschi were not analysed because of recrystallization problems, testified by high proportion of calcite. also red algae samples contained in the calcarenite from the same cave were not suitable for the dating because of the high content of secondary carbonate cement, making the obtained age too young and not consistent with the overall evolution of the area. 55 ppeeddoollooggiiccaall ddaattaa the soil profile of the infreschi cave is characterised by morphological description and bulk sampling for mineralogical analyses (xrd of the fine clay and the sand fractions). the main morphological features are reported in tab. 2. on the basis of the reddish to brownish colours determined with the munsell soil color charts (munsell, 1994), also the redness rate (torrent et al., 1980) was evaluated and applied to estimate hematite content according to ferrari & magaldi (1983): the former values range from 3 to about 12 allowing to predict up to 1.4 % hm (data not shown), approximately accordant with the method proposed by torrent et al. (1983). the weak to null effervescence reaction given by the hcl test (10% solution) allows to estimate no more than 2 % of carbonate in the soil. x-ray diffractometry of the sand fraction indicates the dominance of quartz among the mineral grains, with the presence of feldspars and micas in suborder (data not shown). also calcite was recognised, presumably related to the secondary calcium carbonate precipitations observed. xrd analysis of fine clays shows a mineralogy mainly formed by kaolinite, illite and smectite (fig 11). halloysitic components, possibly deriving from the weathering of the pyroclastic material, cannot be excluded, although no specific treatment was performed to discriminate them from kaolinite. the examined paleosol can be regarded as terrae rossae-like (rhodoxeralfs, sensu usda, 1998), largely widespread in southern italy and other lowand mid-latitudinal areas, and widely studied by several authors (e.g. colombo & terribile, 1994; bellanca et al., 1996; bronger & bruhn-lobin, 1997; yaalon et al., 1997; yassoglou et al., 1997; durn et al., 1999). ccoonncclluussiioonn along the southern sector of the mt. bulgheria, between 12÷10 e 0 m a.s.l. several paleo-sea level evidence was identified and gathered in five range of altitude. the oldest one (12÷10 m a.s.l.) is pre-tyrrhenian in age. the lower evidence develop not continuously along 10 c. esposito et al. sample ppb u (234u/238u) (230th/234u) (230th/232th) (234u/238u) init. age (ka) ri 1 827 ± 17 1.032 ± 0.023 0.373 ± 0.011 40 ± 2 1.037 ± 0.027 50.6 ± 1.9 ri 4 608 ± 42 1.049 ± 0.029 0.565 ± 0.022 38 ± 2 1.063 ± 0.037 89.8 ± 5.4 ri 5 102 ± 4 1.364 ± 0.071 0.588 ± 0.035 infinite 1.472 ± 0.092 91.7 ± 8.2 ri 7 141 ± 5 1.086 ± 0.053 0.650 ± 0.038 infinite 1.118 ± 0.072 111.9 ± 11.0 tab.1u-series data of speleothems from riparo infreschi, (italy). quoted ratios are activity ratios and errors are expressed as 1 sigma. (234u/238u)init. represents the initial uranium activity ratio. datazioni u-series degli speleotemi del riparo degli infreschi, (italia). i rapporti riportati sono rapporti di attività e gli errori sono espressi come 1 sigma. (234u/238u)init. rappresenta il rapporto di attività iniziale dell’uranio. the coastal belt, so it’s difficult to correlate them. moreover, continental and marine deposits associated with these erosional features not provide chronological constraints, with the exception of the deposits surveyed in the infreschi bay. the stratigraphical data collected in the infreschi and riparo infreschi caves were tentatively correlated (tab. 3). the th/u ages of the speleothems sp2-ri1, sp1ri4 and sp1ri5 represent good chronological constraints for the marine sands and conglomerates of the riparo infreschi cave (sn and co2 in figg. 7 and 9) suggesting their attribution to the oiss 5a (>50 ka bp and <89 ka bp). we correlated them to the marine conglomerates and sands that partly fill the nearby infreschi cave and which have the same stratigraphical (are covered by similar graviclastic breccia and paleosol) and altitudinal (in both cases the top of the sands is located at 6 m a.s.l..) position. therefore, these deposits testify a distinct marine ingression in both caves, occurring between two episodes of continental deposition, the last of which is represented by graviclastic breccias and paleosols. in particular, the infreschi cave paleosol shows an intense degree of weathering, probably partly inherited. in fact, it consists of reworked soil sediments with much allochthonous windblown material, previously weathered under interglacial climatic conditions, clearly warmer 11late quaternary shorelines ... tab. 2description of the infreschi cave’s paleosol. descrizione del paleosuolo di grotta degli infreschi. and wetter than today’s. soil reworking should have occurred after the deposition of the marine sands, followed by pedogenesis in the cave, which homogenised this parent material and led to the horizon differentiation and soil aggregation observed in the profile. soil features related to in situ pedogenesis appear compatible with the succession of the last glacial and holocene environments, alternating drier and moister phases at different time scales (103 102 years to yearly and seasonal cycles) and with very different temperature ranges in a “protected” site such as the infreschi cave. the th/u age of the speleothem sp1-ri 7 gives a lower chronological constraint (younger than 111 ka bp) for the evidence of paleo-sea level stands represented by the upper limit of lithophaga. because this limit is located at the same altitude in the infreschi caves we ascribed both evidence to oiss 5c. because of their relative chronological position, other evidence of ancient shorelines collected in the bay can also be ascribed to oiss 5c or to oiss 5a, but it is not clear if they represent complex oscillations within a single stage (substages) or pauses of the same transgressive event. other stages, such as the oiss 5e, have shown to be composed by complex, secondary fluctuations of the paleo-sea level (hearty & kindler, 1995; neumann & hearty, 1996; zazo, 1999). other important considerations have to be made about the altitude of the collected evidence. the top of the marine sands reach in fact 6 m a.s.l. and the upper limit of the burrows is located at 8.5 m a.s.l.; both these altitudes are too high, if compared to the paleo-eustatic level quoted for the oiss 5a and 5c. in fact, even if no agreement has been achieved in the scientific literature about the relative altitude of the sea during these stands, the suggested values are always around or below the present day elevation. in particular, ku eett aall..(1990) and richards et al.(1994) affirmed that both during the oiss 5c and 5a the sea level was much lower than the present one. in contrast, other authors, stated that during the oiss 5a the sea level was close to the present one both in extramediterranean (hearty & kindler, 1995; ludwig et al., 1996) and mediterranean areas (hearty, 1986). for this reason we hypothesise a tectonic uplift of this sector of the coast after the isotopic sub-stage 5a, although we have no elements for estimating the rates and values of this movement. these considerations made us prudent in correlating the other evidence of paleo-sea level stands collected along the coast of mt. bulgheria. however, the evidence collected at 4.5÷4 m a.s.l., which, in most cases, is associated with depositional sand bodies, could probably be correlated to the marine sands and conglomerates of the cala degli infreschi bay and ascribed to oiss 5a. the reconstruction could be complicated by the possibility of hydroisostatic rebounds for each highstand, as proposed in literature for the last highstand (ois 1) (fleming et al., 1998; lambeck & bard, 2000). this model could probably explain the complex fluctuations we found in the infreschi bay but in other sites along the campanian coast the evidence of oiss 5c and 5a are located at different altitudes: 4 m a.s.l. and 1.5 m a.s.l. respectively along the punta licosa promontory (iannace et al., 2001); around 13 m a.s.l. in the sele river plain (brancaccio et al., 1986) and around 2 m a.s.l. in the sorrento peninsula. (riccio et al., 2001), thus testifying the existence of recent tectonic activity along the campanian coast. 12 c. esposito et al. infreschi cave infreschi riparo isotopic stages graviclastic breccia covered by graviclastic breccia containing paleosol with pyroclastic layer remains of mousterian age (130 40 ka bp) covered by pyroclastic layer and flowstones (sp2-ri 1, 50 ka bp) marine conglomerates and marine conglomerates and sands ois 5a sands (sands top at 6 m a.s.l.) that are covered by sp2-ri 1 (>50 that covered a bioconstruction ka bp) and lay on a flowstone with with cladocora coespitosa. lithophaga burrows (sp1-ri 4, ri 5 89 e 91 ka bp, ois 5b). the sands reach an altitude of 6m a.s.l. and they also cover a notch at 3,5 m a.s.l. notch at 3,5 m a.s.l. notch at + 3,5 m bioconstruction with lithophaga burrows between cladocora coespitosa 4/6 m < 89 e 91 ka bp flowstone (sp1-ri 4,ri 5) 89 e 91 ka bp ois 5b wave-cut terrace at + 4,5m. marine conglomerates covered a.s.l.. by sp1-ri 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michela ingrassia1,2, letizia di bella1, francesco latino chiocci1,2, eleonora martorelli2 1 department of earth science, university of rome sapienza, rome, italy 2 cnr-igag (istituto di geologia ambientale e geoingegneria), uos roma, rome, italy corresponding author: m. ingrassia <michela.ingrassia@uniroma1.it> abstract: an active fluid emission area located off the eastern coast of zannone island (western pontine archipelago) has been studied in order to investigate benthic assemblages related to vent-activity. the fluid escape feature is a giant depression (about 0.5 km2) located on the outer shelf, between 110 and130 m water depth. evidences of active emissions were detected by rov observations and sediment sampling, whereas integration of high-resolution multibeam bathymetry, backscatter and ground-truth data allowed us to characterize and identify different seafloor types (e.g., lithified seafloor and sandy sediment). moreover, the analysis of rov videos and grab samples allowed the definition of the benthic assemblages (micro and megafauna) living within the vent-areas and in the nearby seafloor. this study shows results from the first integrated analysis of the morpho-acoustic, sedimentological and biological characteristics of the northern sector of the zannone giant depression, highlighting great differences between vent and non-vent seafloor areas. in vent areas, the seafloor is characterized by high morphological complexity and peculiar benthic habitats strongly controlled by dissolution processes, indicating “extreme” conditions due to active fluid emissions. keywords: active venting; benthic assemblages; foraminifera; shallow-vents; tyrrhenian sea 1. introduction extreme marine environments (emes), as hydrothermal vents and cold seeps, have been found over a wide depth range from coastal to the abyssal zones (hovland & judd, 1988; dando et al., 1999; tarasov et al., 2005; judd & hovland 2007). the most common technology in discovering active marine fluid emission sites is the record of backscatter values in water column, even if often underestimate small-scale venting features (nakamura et al., 2013). recent progress in high-resolution swath mapping techniques and near bottom geophysical surveys (deep-tow manned submersible, remotely-operated vehicle-rov, autonomous underwater vehicle-auv) have permitted to image seafloor morphology in great detail, increasing our knowledge on fluid related features (e.g. tivey & dyment, 2010). during the last decade attention has been mainly devoted to the biological aspects related to the emes, mainly because the occurrence of specific biological communities can be used as indirect proxy to determine the chemical composition of the fluid emitted from the seafloor (sibuet & olu, 1998; sahling et al., 2002; levin & mendoza, 2007; foucher et al., 2009). besides, these particular settings may offer unique opportunities to the discovery of new marine species (takai et al., 2006; danovaro et al., 2010). moreover, micro communities inhabiting these extreme environments assume an important role both in creation and degradation of organic matter and energy, therefore they could be considered a key factor to quantify the amount of greenhouse gases affecting the oceanic chemistry (dimitrov, 2002). seafloor areas affected by hydrothermal activity are mainly found in shallow marine environment (dando et al., 1999; melwani & kim, 2008), but few complete studies about distribution of benthic assemblages have been published, e.g. in the tyrrhenian sea (panieri et al., 2003, 2005; panieri, 2006), aegean sea (dando et al., 1995a,b), south pacific ocean (kamenev et al., 1993; pichler et al., 1999; tarasov et al., 1999), north atlantic ocean (botz et al., 1999), gulf of mexico (melwani & kim, 2008) and in the shallow sub-polar region of the mid atlantic ridge (fricke et al., 1989). more studies are available for cold seep environments (sibuet & olu 1998; levin, 2005). several physical parameters, such as temperature, substrate type, number of emissions, age, concentration of gases (h2s, ch4 and h2) and precipitation of heavy metals, can affect the diversity and spatial distribution of the benthic communities (childress & fisher, 1992; dando et al., 1995b; sibuet & olu, 1998; tarasov, 1999). at shallow water sites the primary production is based both on chemosynthetic and photosynthesis processes (sorokin et al., 1998; namsaraev et al., 1994; tarasov et al., 2005) leading to the scarce occurrence of vent-obligate taxon, respect to those found in deeper sites (dando, 2010). in this paper the first integrated analysis of the morpho-acoustic, sedimentological and biological characteristics of the northern sector of the zannone giant pockmark (described by ingrassia et al., 2015a), located 3 km away from the eastern coast of zannone island (western pontine archipelago), is presented. this result together with direct observations through video-imaging and foraminiferal analysis on recovered samples allowed us to describe the influence of venting activity on sediment characteristics and on micro and mega benthic assemblages. 2. study area the study area is located about 35 km from the latium coastline in the central tyrrhenian sea (italy), on the seafloor surrounding the western pontine archipelago (fig. 1). the western pontine archipelago has a volcanic origin and is located on a structural high where meso-cenozoic basement is overlain by volcanic units of pliocene and pleistocene age (zitellini et al., 1984). the archipelago was affected by extensional tectonics due to the spreading of the tyrrhenian back arc basin (kastens & mascle, 1990), that favored volcanic activity and formation of a very steep, nw-se trending continental slope and a ne-sw oriented structural high (conti et al., 2013). two main stages of volcanism have been recognized in the history of this group of islands. the first stage occurred between 4.2-2.9 ma (cadoux et al., 2005) with the emplacement of rhyolites followed by intrusion of na-rich rhyolitic dikes in marine environment (barberi et al., 1967; savelli, 1983) with hydrothermal activity recorded at ponza island (altaner et al., 2003). subsequently, the volcanic activity was characterized by the production of rhyolites and trachytes between 1.60.9 ma (bellucci et al., 1997; cadoux et al., 2005). a narrow and steep insular shelf, with an average slope of 1°, characterizes the seafloor surrounding the western pontine archipelago. the insular shelf present a complex morphology due to the occurrence of several volcanic, biogenic buildups (martorelli et al. 2003, chiocci & martorelli, in press) and several fluid escape features (ingrassia et al., 2015a). sedimentation on the insular shelf is mainly represented by carbonate sediment composed of foraminifera, coralline algae, bryozoans, ostracods, sponge spicules etc (martorelli et al., 2011). the most important known marine biocenosis are represented by the posidonia oceanica meadows, coarse sands and fine gravels under the influence of bottom currents, coastal detritic bottom, coralligenous (martorelli et al., 2011) and presence of antipatharian corals (ingrassia et al., 2015b). the shelf break is found at a water depth ranging between 90-160 m and it is characterized by a complex trend in the southern sector, where erosive features (channels and canyons) carved the steep continental slope (chiocci et al., 2003). the continental slope is mainly characterized by the occurrence of muddy sediment and sparse volcanic outcrops (conti et al., 2013). finally two tectonicallycontrolled basins (palmarola and ventotene), characterized by high plioquaternary sedimentation rates (zitellini et al., 1984), are located at a water depth ranging between 500-800 m. 2.1. background as reported by ingrassia et al. (2015a) an active fluid emission area, named zannone giant pockmark (zgp), was discovered in 2009 (fig. 2 a and b). the zgp lies in water depth ranging between 110-130 m and it is formed by the coalescence of at least three major craters. within the zgp seafloor three main morphological sectors characterized by hummocky, irregular and regular seafloor have been defined. moreover, about 50 small pockmarks and 28 positive features (mound and cones) were found. across the northern sector of the zgp, bubble streams and acoustic plumes indicate the presence of an ongoing fluid emission activity from the seafloor. water sampling by niskin bottles highlighted the presence of co2, ch4 and c2h6 in fluid emissions. moreover, seismic profiles showed the occurrence of intense deformation of late-quaternary lowstand deposits and holocene highstand deposits, linked to the fluid emissions. 3. material and methods 3.1. acoustic data bathymetry and backscatter data were acquired by the multibeam echosounder system (kongsberg em 3002d 300 khz), during a research cruise “magic igag 10/09” carried out on november 2009 on board of the r/v maria grazia (by cnr-igag). navigation data was d-gps positioned and sound velocity parameters were collected via multiple conductivity, temperature and depth (ctd) casts. 100 fig.1 bathymetry (by gebco digital atlas) of the southern latium continental margin. red box indicate location of the study area. pa=palmarola; po=ponza; za=zannone; ve= ventotene. ingrassia m. et al. 101 fig. 2 a) shaded relief image (grid size of 5 m) of the seafloor surrounding the eastern part of zannone island, with the location of grab samples and track of video observations; b) detail of the backscatter mosaics (both sss and multibeam) obtained for the northern sector of the zgp (zannone giant pockmark); c) detail of the multibeam backscatter mosaic for the non-vent seafloor areas located on the outer insular shelf. vent-activity affecting the marine environment at zannone island (central italy) backscatter data were acquired by the eg&g 260 side scan sonar (sss) during a research cruise (magic igag 2012) carried out on february 2012 on board r/v urania (by cnr-igag). bathymetric data were post-processed using the software caris hips & sips 8.1.7. sensor data were merged and corrected for the effect of tide, attitude sensors (roll, pitch and heave) and sound velocity variation. acquisition and processing of multibeam data are detailed described in casalbore et al. (2014). for this work, digital terrain models (dtms) were produced at a resolution varying from 1 to 5 m (fig. 2a). visualization of dtms was obtained using the software global mapper 15. backscatter data were processed through the geocoder tool using the software caris hips & sips 8.1.7. this processing allowed to obtain different multibeam backscatter mosaics (pixel resolution varying from 1-0.5 m; fig. 2b and c) and an ultra-high resolution sss mosaic (0.2 pixel; fig. 2b). backscatter signatures were classified according to their textures via a qualitative description. 3.2. ground-truth data (sediment and biological evidence) sediment, biological and video data (fig. 2) were acquired during two research cruises the “s.g.n. 2001”, carried out on july 2001, and the “bolle 2014” carried out on june 2014 aboard to the r/v urania. in 2001, 68 video observations were acquired by the hyball2 rov system and in 2014 13 dives were performed using the pollux iii (gei) rov system. this rov was equipped with an underwater acoustic tracking positioning system (ultra-short baseline, usbl) that provided detailed records of the seafloor tracks. four sediment samples (tab. 1 and fig. 2) were collected with a van veen grab during the research cruise “bolle 2014”. sample locations were identified during the video transect acquisition, in order to obtain representative biological and sedimentological information in both vent and non-vent seafloor areas. on board all the samples were visually described, photographed and preserved by freezing. 3.2.1. foraminiferal faunal analysis for each of the four collected grab samples (fig. 2) a significant undistributed surface sample (0-1 cm thick) was considered for preliminary environmental characterization of the studied area by mean of living and dead benthic foraminiferal assemblages. in this respect, the sediment samples were stained and preserved in a solution of 2 g/l of rose bengal of ethanol as described by lutze & altenbach (1991) and schönfeld et al. (2012). after 15 days, the samples were wet-sieved through a 63 �m sieve and then dried at 60°c. in each sample rose bengal stained foraminifers with well-preserved tests were counted, hand-picked and identified using a binocular microscope. the classification of the species has been made on the base of recent mediterranean and extramediterranean foraminiferal literature data (jorissen, 1987, 1988; cimerman & langer, 1991; sgarrella & moncharmont-zei, 1993; sen gupta et al., 2009; frezza et al., 2010; milker et al., 2012). the species diversity was quantified using the áfisher index (fisher et al., 1943) calculated using the past (palaeontological statistics) version 1.38 data analysis package (hammer et al., 2001). 4. results integration of high-resolution bathymetry and backscatter data allowed to recognize the main characteristics of the seafloor around the sampled stations (grabs) and of the nearby seafloor areas (fig. 3). moreover, the ground-truth data (biological and sedimentological evidence) allowed us to determine the main differences between vent and non-vent areas. 4.1. vent seafloor areas herein a geophysical and sedimentological/ biological description of the two grab samples (st2bnr1 and st4bnr1, fig. 2b), located in the vent area, is given. st2bnr1 was recovered at 137 m water depth, within an elongated depression located in the northern sector of the zgp (fig. 2b and fig. 3a). this depression is 217 m long, 65 m wide and has an average slope of 10°. moderate to high intensity values and several acoustic shadows (fig. 2b and fig. 3a) characterize the seafloor surrounding the sampled station, as evidenced by the backscatter data. this grab recovered sandy sediment and pieces of hard-lithified sediment (fig. 3a) with a strong sulfur smell. rov2 shows different types of seafloor both in correspondence and around the sampled station (fig. 2a and b). to the south, the seabed is floored by sandy sediment, sometimes covered by bacterial mats, characterized by the occurrence of several small pockmarks with centimetric size (fig. 4a). one specimen of sea urchin, belonging to the family cidaridae (fig. 4b), represents the benthic megafauna. the second type of seafloor is characterized by the presence of larger depressions (fig. 4c), with occurrence of small positive cones. only few specimens of fishes, jumping on the seafloor, were observed. in the north-eastern sector the seafloor is characterized by occurrence of coarse sediment (fig. 4d). no direct evidences of fluid emissions were detected via video observations (e.g. bubble streams) on the seafloor surrounding the st2bnr1 station. however water column backscatter data show the occurrence of a 40-70 m high, well defined acoustic flare (ingrassia et al., 2015a). x-ray diffraction revealed as in this station the inorganic fraction is mainly constituted of quartz, glass, rare feldspars, native sulfur and barite. no living microfauna 102 tab. 1 list of the grab samples considered in this study (geographic coordinates). ingrassia m. et al. were observed at this station. st4bnr1 was recovered at 133 m water depth, within a complex pockmark (fig. 2a, b) composed of two small depressions characterized by a total length of 78 m, width of 65 m and average slope of 5°. within the complex pockmark the backscattered signal is homogeneous and varies between low and moderate intensities (fig. 3b); in contrast the seafloor around the rim of the pockmark is characterized by very high backscattering strength (fig. 3b). the grab recovered well sorted sandy sediment with traces of oxidation (fig. 3b). rov6 shows different types of seafloor both in correspondence and around the sampled station (fig. 2a and b). along the north-eastern flank of the complex pockmark (close to the grab station) at least six active emissions, associated to bubbles streams or cloud of fluids (fig. 4e), were observed. no continuous fluid emissions are observed on the pockmark floor that is composed of oxidized sandy sediment, characterized by centimetric (5-10 cm) circular depressions and small cones, with occurrence of widespread bacterial mats (fig. 4f). no megafauna was observed both nearby to the active emissions points and on the pockmark floor. lithified sediments, forming domal structures (fig. 4 g, h and i), were observed in correspondence of the rim of the pockmark. in some cases, these structures are characterized by presence of flange-like features, where filamentous bacteria (fig. 4h) and hydroids (fig. 4 i) are present. moreover, fish schools of anthias anthias were observed swimming in the proximity of the domal 103 fig. 3 summary of the acoustic facies (bathymetry and backscatter) and sediment characteristics for each sampled stations. vent-activity affecting the marine environment at zannone island (central italy) 104 ingrassia m. et al. structures (fig. 4 l). x-ray diffraction revealed as in this station the inorganic fraction is dominant. it is mainly constituted of quartz, glass and rare feldspars. instead, only siliceous spicules and very rare living agglutinated foraminifers represent the organic fraction. the dominant morphotypes are trochoid and elongated species mainly attributed to species pertaining to trochammina, reophax and lagenammina genera. the specimens show very small sizes with shell diameters <30 ìm, exclusively constituted of quartz particles. no porcellanaceous and hyaline tests were recorded and the dead assemblage was completely absent, as a result, faunal density and species diversity are extremely low. 4.2. non-vent seafloor areas two grab samples were collected in non-vents seafloor areas (fig. 2a and c). these samples were analyzed in order to obtain a comprehensive background of the type of habitats present in the study area. st5bnr1 and st6bnr1 samples were recovered on the outer shelf of zannone island, at about 2.5 km from the zgp, in a water depth of about 126 m (fig. 2a and c). the sampled stations are placed on a flat seafloor (fig. 2a and fig. 3c, d) characterized by average slope value of 0.7°. backscatter intensity is rather homogeneous with intermediate values (fig. 3c and d). both the samples recovered sediment composed of sandy sediment with traces of oxidization and bivalve shells (fig. 3c and d). no video observations are available in the correspondence of st5bnr1 and st6bnr1 stations. in both samples inorganic fraction is scarce and mainly constituted of quartz, calcite, and volcanic clasts. the organic fraction is very abundant; it is represented by sponge spicules, ostracods, pteropodes, briozoa, mollusk fragments and foraminifers. among these components, benthic foraminifers dominate the sediment residue. foraminiferal tests are generally well-preserved although the dead assemblage is more abundant than the living one. a total of 59 species were recognized. the species diversity performed on the total assemblage is high with á-fisher index value of 21.02. the total assemblage is characterized by asterigerinata planorbis, cassidulina spp., elphidium spp., lobatula lobatula, rosalina spp., uvigerina spp. and frequent miliolids (miliolinela spp. biloculinella spp., pseudotriloculina spp.). in detail, the living assemblage is characterized by miliolinella subrotunda, biloculinella labiata, biloculinella depressa, quinqueloculina spp., nubecularia lucifera, uvigerina mediterranea, hoeglundina elegans, cassidulina spp., spiroloculina excavata. rov dives r43, rov2 and rov8, showing the main characteristics of the non-venting areas, were acquired on the seafloor located close to the northern escarpment and along the north-western rim of the zgp (fig. 2a and b), in a water depth ranging between 84– 120 m. r43 displays occurrence of widespread biodetritic sandy sediment with a significant amount of coralline algae, e.g. pralines (fig. 5a and b), whereas no mud sediment was observed. the benthic megafauna is represented by sea urchins belonging to the families cidaridae and echinidae (fig. 5a and b). rov2 shows the occurrence of several rocky outcrops interspersed with sandy sediment along the north escarpment of the zgp (fig. 5c) with holothurians, sea stars (fig. 5d), sea urchins (cidaridae) and school of a. anthias. moreover, the video images reveal traces of anthropogenic impacts as fishing activities (fig. 5e) and presence of a lost cable (fig. 5f). finally, rov 8, located 200 m nw from the zgp (fig. 2a and b), shows occurrence of sandy sediment with a large number of sea urchins belonging to the family cidaridae. 5. discussions 5.1. non-vent vs vent seafloor areas the analysis of morphological and backscatter data as well as sedimentological and biological information derived by ground-truth data highlight significant differences between vent and non-vent areas. non-vent areas are characterized by a smooth seafloor, with low backscatter intensity due to sandy sediment without occurrence of fluid escape features. this is the normal seafloor environment for the outer shelf of the pontine seafloor, where lowstand deposits are present, as described in martorelli et al. (2011) and chiocci & martorelli (in press). this environment hosts different benthic fauna (sea urchins -cidaridae and echinidae-, holothurians, coralline algae, etc.) and school of a. anthias. here, the foraminiferal assemblages (dead and living) appear strongly diversified with high faunal density, suggesting a stable environment. on the base of the ecological characteristics of species, the assemblages can be related to mesothrophic-oligothrophic and well oxygenated bottom conditions. this is confirmed by the dominance of epifaunal (miliolids, a. mamilla, l. lobatula) and shallow infaunal species (cassidulina spp., uvigerina spp.) that usually live in environments with supply of fresh organic matter continually provide by currents (langer, 1993; hayward et al., 2013; nardelli et al., 2010; de rijk et al., 2000). similar assemblages are common and widespread on the seafloor of the whole western pontine archipelago, as shown by frezza et al. (2010). on the contrary within the vent-areas, the seafloor is characterized by a complex morphology, encompass 105 __________________________ fig. 4 selected rov-images taken in correspondence of the sampled vent-seafloor areas. a) bacterial mat on sandy sediment with occurrence of several small depressions; b) sea urchin (cidaridae) on sandy sediment; c) sandy sediment with presence of large depression; d) coarse sediment; e) cloud-fluid emission from the sandy seafloor; f) oxidized sandy sediment with occurrence of widespread bacterial mats, several centimetric circular depressions and small cones; g) domal structure with visible flange like feature; h) domal structure with filamentous bacteria; i) specimens of hydroids observed on the domal structure; l) school of a. anthias swimming in the proximity of the domal structure. vent-activity affecting the marine environment at zannone island (central italy) ing pockmarks of various size, dome and cones structures, and different types of substrata (lithified sediment, crusts, sandy sediment, etc.). the detection of lithified sediment inside the zgp and not on the nearby seafloor (non-vent areas) strengthens the interpretation of these features as vent-related crusts. according to tarasov et al. (2005), canet et al. (2006) and griffith & paytan (2012), presence of barite and native sulfur, white bacte 106 fig. 5 selected seafloor rov-images taken in correspondence of the sampled non-vent seafloor areas. a) coralline algae and sea urchin (cidaridae) on biodetritic sediment; b) biodetritic sediment with occurrence of a specimen of sea urchin belonging to the family echinida (white narrow); c) rocky outcrops interspersed with sandy sediment d) specimen of sea star on hard sediment; e) lost long-line gear on rocky outcrop; f) lost cable on biodetritic sediment. ingrassia m. et al. rial mats and several centimetric small pockmarks, provides further evidence of relevant continuous fluid emissions in this area. moreover, as indicated in section 4.1, some of these structures appear characterized by the development of flange-like features, similar in aspect to those commonly observed along the lateral side of vertical and large sulphide chimneys (kerr, 1997), formed by hydrothermal circulation in deep water settings (tivey, 2007). as no flange-like features have been reported in shallow water environment, their finding within the zgp (at about -130 m) updates the knowledge on environment condition leading the formation of these peculiar structures. as a whole, the occurrence of different seafloor types seem reflect a high complexity and variability of both seafloor morphology and sediment characteristics, that in many cases change at metric scale (e.g. transition from dome structures to pockmarking sandy sediment). the main benthic assemblages found in the ventareas are represented by widespread bacterial mats, sea urchins belonging to the family cidaridae, hydroids and presence of schools of a. anthias (fig. 4g, h, i and l). the broad presence of bacterial mats observed only within the floor of the zgp, close or directly above vent emissions, indicate that occurrence of fluid emissions in shallow-water environment plays a direct control on bacterial mats distribution; this evidence is consistent with observations obtained by levin et al. (2000) and tarasov et al. (2005). no obligate megafaunal assemblages were observed close to the vent emissions and in their proximity, actually megafauna is completely absent on vent emissions. after all, one of the common factor limiting the colonization of benthic megafauna is represented by the concentration of hydrogen sulphide (vismann, 1991). the appreciable sulfur smell detected in the st2bnr1 grab sample suggests the occurrence of fluids moderately enriched in h2s, which could be toxic for the organisms. in more distal areas from venting zones, the distribution of the megafauna appears rather similar to that observed on the non-vent seafloor; this result is in agreement with other reference studies (i.e. dando et al 1995b; thiermann et al., 1997; morri et al., 1999; tarasov et al., 1999). a different situation arise from the analyses of foraminifera that indicate major differences between vent and non-vent areas. in fact, the typical microfaunal assemblage of vent-areas is represented by oligotypic foraminifera constituted exclusively of agglutinant species. this assemblage is very different, for structure and composition, from the associations recorded at the same depth (around 126 m) in areas located outside the zgp, which are not influenced by fluid emissions. in the vent areas the abrupt decrease of faunal density and species diversity associated to the decrease in shell size of the living specimens, indicates a stressed environment unfavorable to benthic life. the exclusive presence of agglutinant species, in fact, suggests chemical and physical conditions not suitable for carbonate shell formation and/or preservation, both hyaline and porcelanaceous tests. as the fluids emitted from the seafloor, located in the northern sector of the zgp, are characterized by enrichment in co2 (ingrassia et al., 2015a), acidification of water might explain the lack of carbonate tests in the foraminiferal assemblages (uthicke et al., 2013). moreover acidification might be enhanced by local enrichment in co2 produced by bacterial activity through anaerobic methane oxidation reaction (sen gupta et al., 2009; dando, 2010; wankel et al., 2012). the lack of dead foraminiferal assemblages (both benthic and planktonic) suggests the occurrence of strong dissolution processes, confirmed by the sediment composition (only quartz) from which the organisms take and agglutinate their tests by mean of organic cement (cimerman & langer, 1991). agglutinant species, above all trochammina spp. that are the most abundant, seem to be the most resistant to the zgp stressed environment showing an opportunistic behavior. this hypothesis is supported by the record of similar assemblages found in other vent-seafloor areas located in the tyrrhenian sea (aeolian arc), although they appear more abundant and diversified (panieri et al., 2003, 2005; panieri, 2006) than those analyzed in this study. 6. conclusions in the present study the morpho-acoustic, sedimentological and biological characteristics of the northern sector of the zgp have been analyzed. results from this study highlight great differences among the morphology, sedimentology and microfauna characters between vent and non-vent seafloor areas. on the contrary, the distribution of the megafaunal assemblages highlights a different situation. in fact, the benthic megafauna observed in vent-seafloor areas seems to represent a subgroup of the typical environment condition, while megafaunal assemblages are completely absent in areas affected by active venting. in vent-areas, the benthic foraminiferal assemblages highlight the complete lack of both hyaline and porcelanaceous tests suggesting the presence of strong dissolution processes. for all these aspects the shallow water fluid emissions site (zgp) could be considered as an extreme environment and a natural laboratory for studying the effects of co2 enriched fluids on benthic communities, with particular interest for the organisms that produce calcareous skeletons. acknowledgements this research was performed in the framework of the flagship project ritmare (sp4-wp2-a1). crews of r/v urania and maria grazia are gratefully acknowledged for their precious work. we would also thank the reviewers, daniele casalbore and romana melis, and the editor andrea sposato for their valuable comments and suggestions that greatly improved the quality of the manuscript. references altaner s.p., ylagan r.f., savin s.m., aronson j.l., belkin h.e., pozzuoli a. 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(2012) anaerobic methane oxidation in metalliferous hydrothermal sediments: influence on carbon flux and decoupling from sulfate reduction. environmental microbiology, 14(10), 2726-2740. zitellini n., marani m., borsetti a. (1984) post-orogenic tectonic evolution of palmarola and ventotene basins (pontine archipelago). memorie della società geologica italiana, 27, 121-131. ms. received: may 18, 2015 final text received: june 10, 2015 110 ingrassia m. et al. impaginatodavanzo mmaammmmaall sskkeelleettaall rreemmaaiinnss ffrroomm tthhee ffuummaannee ccaavvee ((vveerroonnaa,, nnoorrtthheerrnn iittaallyy)):: aann ooxxyyggeenn iissoottooppee ssttuuddyy aanndd iittss ppaallaaeeoocclliimmaattoollooggiiccaall iimmpplliiccaattiioonnss ss.. ddaavvaannzzoo,, pp.. iiaaccuummiinn && aa.. lloonnggiinneellllii university of parma, department of earth sciences, parco area delle scienze 157/a, 43100 parma, italy abstract a stable isotope study of mammal skeletal remains of palaeolithic age from the fumane cave (verona, n. italy) was carried out to obtain palaeoclimatological information. the studied samples belong to capra ibex, cervus elaphus, capreolus capreolus and bos/bison sp. and come from various levels of the cave deposits of upper and mid palaeolithic age. the δ18o of palaeoenvironmental water was calculated from the δ18op measured on fossil samples, according to the isotope equations previously calibrated on modern specimens. the results obtained suggest that teeth must be considered with great caution for palaeoclimatic reconstruction: in the case of this study they yield quite unreliable results. in a general way, isotopically well-preserved bones are preferrable since the interpretation of their results is more straightforward, more reliable and more meaningful, the bone phosphate representing a mean value of a considerable period of the life of each specimen. the δ18ow calculated from bone samples indicate that the climatic conditions were colder than at present. further isotope data are of importance as a database for detailed reconstructions of the past climatic conditions along ns and ew geographic sections in europe. riassunto sono state eseguite misure della composizione isotopica del fosfato (δ18op) su resti di mammiferi fossili provenienti dalla grotta di fumane (verona) allo scopo di ottenere informazioni paleoclimatiche quantitative o almeno semiquantitative per il paleolitico mediosuperiore nella zona in esame. i campioni provengono da vari livelli di una successione stratigrafica divisa in quattro unità principali (s, br, a e d) ed appartengono alle specie capra ibex, cervus elaphus, capreolus capreolus e bos/bison sp.. i valori di δ18o delle “paleo” acque meteoriche sono stati calcolati a partire dai valori di δ18op misurati sui campioni fossili utilizzando le equazioni isotopiche preventivamente calibrate su individui recenti. i risultati ottenuti indicano che i denti non sono sempre utilizzabili per ricostruzioni paleoclimatiche e che, in generale, è preferibile utilizzare le ossa, almeno quando si ha a che fare con materiali non interessati da processi diagenetici. i valori di δ18ow (acqua paleoambientale) calcolati dai campioni di ossa confermano che il clima, nell’intervallo di tempo relativo alla successione esaminata, era sensibilmente più freddo di quello attuale. questi risultati costituiscono un utile apporto per dettagliate ricostruzioni delle variazioni climatiche nel passato lungo sezioni ns ed eo in europa. keywords: fumane cave, oxygen isotopes, palaeoclimatology, upper and mid-palaeolithic parole chiave : grotta di fumane, composizione isotopica dell’ossigeno, paleoclimatologia, paleolitico medio-superiore il quaternario italian journal of quaternary sciences 1155(1), 2002, 39-44 11.. iinnttrroodduuccttiioonn the fumane cave (verona-northern italy) has been studied by archaeologists for its deposits from palaeolithic age. the cave is located at about 350 m.a.s.l. on the lessini mountains (fig.1). it was repeatedly excavated throughout the last century and an extensive excavation (10 m of sediments) was carried out by the historical museum of verona and the sovraintendenza alle antichità from 1982 to 1983 and by the prehistoric and ethnographic museum “pigorini” of rome from 1987 to recent time (bartolomei et al., 1992a). the 10 m of sediments were divided into four units (d, a, br and s), each one in turn being subdivided into various levels and sublevels. 29 radiocarbon dates are available for 9 of the stratigraphic levels of the d and a units of the fumane cave. the d unit dates approximately from 27,000 to 32,000 bp and the a unit from 32,000 to 38,000 bp. (for a complete review see bartolomei et al., 1992a,b; cassoli and tagliacozzo, 1994; cremaschi et al., 1986; peresani and sartorelli, 1996). three thermoluminescence dates were carried out on burnt flint stones from levels br11, br12 and s7 yielding ages of about 55, 57 and 80 ka bp respectively (broglio, personal communication). deer and ibex are the most abundant faunal remains at fumane cave followed by roe deer, chamois and bovines with subordinated marmot and fox. these remains are essentially human food refuse. micromammals are also well represented. the study of mammal assemblages and sedimentary analyses from the a and d units point to a wooded landscape and a cool climate at lower levels (a13-a3) and to an open landscape with a cold and arid climate at higher levels (a2-d1) (bartolomei et al., 1992b). 40 davanzo-iacumin-longinellii while the analyses of faunal assemblages from archaeological sites can yield only qualitative palaeoclimatological information, oxygen isotope analyses can provide a quantitative or semi-quantitative information of past climatic conditions in the case of suitable material. mammal bone and tooth oxygen isotope data enable the calculation of the mean oxygen isotope composition of environmental water throughout the period covered by the samples studied. in fact, the δ18op values can be converted into δ18o of palaeoenvironmental water by means of isotope equations calibrated on living specimens of the same species from different climatic areas (e.g. longinelli, 1984; longinelli, 1995; delgado huertas et al., 1995). these equations take into consideration the different metabolic processes characteristic of each species and the overall isotope fractionation of the oxygen taken in. in turn, the mean δ18o value of environmental water is related quantitatively to the yearly mean temperature at the ground. consequently, the δ18op values can be considered variables quantitatively related to palaeoclimatological conditions. 22.. mmaatteerriiaallss aanndd mmeetthhooddss the study was carried out on 119 mammal bone and tooth enamel samples belonging to cervus elaphus, capra ibex, capreolus capreolus and bos/bison sp. in the case of teeth, the enamel sample portion analysed was collected in such a way as to represent the whole period of tooth accretion. consequently, the intra-tooth variation related to seasonal climatic changes is considerably reduced. the samples were prepared according to well established procedures (crowson and showers, 1991 and lécuyer et al., 1993). the final sample of the chemical treatment is ag3po4.the phosphate oxygen is extracted from the samples by reacting the ag3po4 with brf5 at 600°c for about 15 hours. the oxygen is then purified and converted to co2 by cycling over hot graphite in the presence of a platinum catalyst; the co2 is measured for its 18o/16o ratios by means of a mass spectrometer (in this case a finnigan delta s). the isotope results are reported in the δ terminology versus the international v-smow standard. 33.. iissoottooppee rreessuullttss aanndd ddiissccuussssiioonn the phosphate oxygen isotope composition (δ18op) of the measured samples and the oxygen isotope composition of local environmental water (δ18ow) are reported in table 1 along with their stratigraphic position in the cave sedimentary sequence. the δ18ow was calculated from the δ18op values according to the equations suggested by d’angela and longinelli (1990) for cervus and bos and by delgado huertas et al. (1995) for capra and capreolus. the same δ18ow values are also reported graphically in figure 2. the δ18ow calculated from bone samples range from -10.2 to -6.2 per mil with a mean value of -7.8±0.8. the mean δ18ow calculated from tooth samples (-9.6±2.3) is surprisingly lighter than that of bone samples ranging between -13.4 and -3.9 per mil. in general, tooth enamel is considered the most reliable material for δ18op analyses due to its capability of retaining the pristine isotope value throughout long periods (e.g. ayliffe et al., 1994). however, tooth phosphate is not renewed during the lifetime of an individual and, consequently, it records the isotopic signature of climatic conditions referring to a very short period of the individual’s life (bryant et al., 1996; fricke and o’neil, 1996). this is particularly true for the teeth that mineralise during the weaning period which are affected by the nursing processes. in the case of our samples and particularly for the c. ibex from which a number of teeth were measured in the lower units (br and s) the δ18ow values calculated from teeth δ18op are systematically 18o-depleted when compared to δ18ow calculated from bone values, even from the same level (fig.2). only very few teeth values behave in the opposite way being 18o-enriched. since diagenetic processes normally affect preferentially bones leading to an 18o-depletion, this effect can hardly be ascribed to post-depositional processes. therefore, according to the results obtained the time period represented by the br and s units could be considered slightly colder than the period represented by the d and a units. however, this hypothesis is not confirmed by the measurements obtained from other species and, particularly, by the deer samples, several of which were analysed from the br and s levels. it may be inferred that: 1) the ibex fawns lived at a higher elevation; 2) they lived in an area where streams carried down isotopically lighter water from the nearby alpine glaciers; 3) that they were born in a given period so that the permanent teeth mineralised preferentially during the cold season. the 18o-enriched teeth values may be ascribed to the weaning period since milk water is considerably 18oenriched when compared to environmental water (luz et al., 1984). because of the great difference between bone and fig.1 location of the fumane cave, north-eastern italy. ubicazione della grotta di fumane. 41mammal skeletal remains ... lleevveell ssppeecciimmeenn sskkeelleettaall δδ 1188oo pp δδ 1188oo ww rreemmaaiinnss d1e c. ibex bone 17.2 -7.9 d1e c. ibex bone 17.7 -7.3 d1e+d1d c. ibex bone 16.8 -8.4 d1e+d1d c. ibex tooth 12.3 -13.4 d1d c. ibex bone 17.7 -7.3 d1d c. ibex bone 17.5 -7.5 d1c c. ibex bone 16.9 -8.2 d1c c. ibex bone 16.9 -8.2 d1c c. ibex bone 18.2 -6.7 d1a c. ibex bone 15.1 -10.2 d1a c. ibex tooth 20.7 -3.9 d3b c. ibex bone 17.4 -7.6 d3b c. ibex bone 17.9 -7.0 d3b c. ibex tooth 19.4 -5.4 d5 c. ibex bone 17.2 -7.8 d5 c. ibex bone 18.4 -6.5 d6 c. ibex bone 18.2 -6.7 d6 c. ibex tooth 15.2 -10.1 d6 c. ibex tooth 15.9 -9.3 d6 bos/bison sp. bone 16.7 -8.2 d6 bos/bison sp. bone 15.7 -9.1 d6 bos/bison sp. bone 17.9 -6.9 d6 bos/bison sp. bone 15.5 -9.3 a1 c. ibex bone 17.6 -7.4 a1 c. ibex bone 17.6 -7.4 a1 c. ibex bone 17.6 -7.4 a1 bos/bison sp. bone 17.3 -7.6 a1 bos/bison sp. tooth 12.8 -12.0 a2 c. ibex bone 17.7 -7.3 a2 c. ibex tooth 16.7 -8.4 a2 c. ibex tooth 15.2 -10.2 a3 c. ibex bone 17.0 -8.1 a3 c. ibex tooth 17.8 -7.2 a3 bos/bison sp. tooth 15.1 -9.7 a4 c. elaphus bone 16.5 -8.1 a5+6 c. ibex bone 16.5 -8.6 a5+6 c. ibex tooth 17.4 -7.7 a5+6 c. elaphus bone 16.3 -8.2 a5+6 c. elaphus bone 16.9 -7.7 a6 c. ibex bone 16.8 -8.3 a6 c. capreolus bone 17.9 -7.1 a6 c. capreolus bone 17.7 -7.3 a7 bos/bison sp. bone 15.0 -9.8 a10 c. ibex bone 18.4 -6.5 a10 bos/bison sp. tooth 14.2 -10.6 a11 bos/bison sp. tooth 15.1 -9.7 a11 bos/bison sp. tooth 16.2 -8.7 br1 c. ibex bone 17.6 -7.4 br1 c. elaphus bone 17.7 -7.0 br3 c. ibex bone 16.8 -8.3 br4 c. ibex bone 17.4 -7.7 br5 c. ibex bone 17.0 -8.1 br5 c. elaphus bone 16.8 -7.8 br5 c. elaphus bone 17.5 -7.2 br6 c. elaphus bone 17.1 -7.5 br6 c. capreolus bone 16.7 -8.4 br7b c. elaphus bone 17.4 -7.3 br7b c. elaphus bone 17.2 -7.4 br7b c. elaphus bone 16.1 -8.4 lleevveell ssppeecciimmeenn sskkeelleettaall δδ 1188oo pp δδ 1188oo ww rreemmaaiinnss br7c c. elaphus bone 17.4 -7.3 br7f c. elaphus bone 17.6 -7.0 br7f c. elaphus bone 17.7 -6.9 br7f c. capreolus bone 16.7 -9.2 br7f c. capreolus bone 15.9 -9.3 br8 c. ibex bone 17.2 -7.8 br8 c. elaphus bone 17.3 -7.3 br9 c. ibex bone 16.9 -8.2 br9 c. elaphus bone 18.5 -6.2 br9 c. elaphus bone 17.1 -7.5 br9 c. elaphus tooth 16.5 -8.1 br9 c. capreolus bone 16.6 -8.5 br10 c. ibex bone 17.5 -7.5 br10 c. ibex tooth 12.4 -13.4 br10 c. ibex tooth 18.0 -7.0 br11d c. ibex tooth 15.9 -9.3 br11d c. elaphus bone 17.0 -7.7 br11d c. elaphus bone 17.6 -7.0 br11d c. elaphus bone 15.9 -8.6 br11d c. capreolus bone 17.3 -7.8 br11d c. capreolus bone 17.7 -7.3 br12 c. elaphus bone 16.6 -8.0 br12 c. elaphus bone 17.8 -6.9 br12 c. elaphus bone 17.4 -7.3 br12 c. elaphus tooth 16.1 -9.1 br12 c. capreolus tooth 14.2 -11.3 br12 c. capreolus bone 15.7 -9.6 s2 c. elaphus bone 16.5 -8.0 s2 c. elaphus bone 17.1 -7.5 s2 c. elaphus bone 17.0 -7.6 s2 c. ibex tooth 14.9 -10.5 s2 c. ibex tooth 14.8 -10.6 s2 c. capreolus bone 17.5 -7.6 s2 c. capreolus bone 17.9 -7.0 s2 c. capreolus bone 17.6 -7.4 s3 c. elaphus bone 16.8 -7.7 s3 c. elaphus bone 16.9 -7.7 s3 c. elaphus bone 16.1 -8.4 s3 c. elaphus bone 17.3 -7.3 s3 c. ibex tooth 14.8 -10.6 s3 c. ibex tooth 14.3 -11.1 s4 c. elaphus bone 17.0 -7.6 s4 c. elaphus bone 16.3 -8.2 s4 c. elaphus bone 16.8 -7.7 s4 c. ibex tooth 12.5 -13.2 s4 c. capreolus bone 18.4 -6.5 s5 c. elaphus bone 15.3 -9.1 s5 c. elaphus bone 16.3 -8.2 s5 c. ibex tooth 14.8 -10.6 s6 c. elaphus bone 16.0 -8.5 s6 c. elaphus bone 17.4 -7.2 s6 c. elaphus bone 17.0 -7.6 s7 c. elaphus bone 17.2 -7.4 s8 c. elaphus bone 16.5 -8.0 s8 c. elaphus bone 16.8 -7.7 s8 c. elaphus bone 17.8 -6.9 s8 c. elaphus bone 14.1 -10.2 s9 c. elaphus bone 16.8 -7.7 s9 c. elaphus bone 14.4 -9.9 tab.1 δ18op of the samples measured, their stratigraphic position and calculated δ18ow values. valori di δ18op dei campioni misurati, la loro posizione stratigrafica e i valori calcolati di δ18ow. 42 tooth values and the uncertainty on the meaning of the observed difference, teeth were not used for the reconstruction of the palaeoclimatic curve. apart from a few cases the δ18ow values calculated from the δ18op of c. ibex, c. capreolus, c. elaphus and bos/bison sp. bone samples are rather similar along the stratigraphic sequence (fig.3). the observed similarity suggests similar δ18o values for the water taken in by the specimens of the different species despite their different behaviour. if the mean δ18ow values of all the samples measured are taken into consideration the solid curve can be traced through the sequence (fig.3). this curve is characterised by very small δ18ow oscillations and does not show a significant trend, most of the samples yielding results that are not very far from modern mean values of atmospheric precipitation and of environmental water in that area (about -7.5 / -8.0 per mil). this consideration is not acceptable since the time interval considered is known as a cold period belonging to the last glacial. to explain this apparent inconsistency in the results it must be assumed that during glacial periods the isotope composition of ocean water was considerably enriched in heavy isotopes (18o and d) when compared to modern ocean water (shackleton and kenneth, 1975). this enrichment is related to the storage of huge amounts of isotopically light water in the thick and expanded ice caps covering large areas of the northern hemisphere. since the mediterranean basin is known to amplify the climatic effects considerably, it can be assumed that, during the last glacial period, oceanic water was at least 1 to 1.5 per mil heavier than now and the mediterranean water was, very likely, heavier by 1.5 to 2 per mil than now. accordingly, the oxygen isotope composition of the atmospheric water vapour and the atmospheric precipitation were 18o enriched by about the same amount. this means that the mean δ18ow value obtained from most of the samples measured should be shifted by about 2 per mil towards lighter (colder) values. such a shift corresponds to a temperature decrease of about 5°c that can be reasonably accepted to represent the mean difference between the average conditions of the last glacial in this area and modern conditions. if the most negative values obtained are taken into account the δ18ow obtained from levels s8 and d1a are lighter than the modern mean isotope composition of local meteoric water by about 2/2.5 per mil. on the basis of the modern mediterranean temperature gradient (0.39 per mil) the difference between the modern value and the lowest results obtained would correspond to a negative gradient in the yearly mean air temperature of about 9.0/11.0°c if the variation of 1.5/2 per mil of the oxygen isotope composition of the mediterranean water is taken into account. these values seem to be too high and in this case it is worth suggesting once more the possibility that these very negative values may be related to specimens that drank stream water from alpine glaciers or, at least, from high mountains. it is also possible that, given the incompleteness of our curve, the coldest periods are not documented because the cave was not occupied. davanzo-iacumin-longinellii fig.2 oxygen isotope composition of palaeoenvironmental waters calculated from the measured δ18op values reported according to the stratigraphic position of the samples. solid symbols are bones, open symbols are teeth. valori di δ18o dell’acqua paleoambientale, calcolati dai valori di δ18op dei diversi campioni riportati in funzione della loro posizione stratigrafica. i simboli pieni si riferiscono a campioni di ossa, gli altri a campioni di denti. 43 44.. ccoonncclluussiioonnss the reported stable isotope study suggests that: when possible, it is better to avoid the use of fossil teeth for palaeoenvironmental reconstruction along a stratigraphic sequence because they record the conditions existing during a short period of the individual’s life. this short period can be “isotopically” different in comparison to their overall life; the studied samples recorded the climatic conditions during a period considerably colder than the present one with colder climatic episodes; the temperature gradient between the studied period and recent time was not lower than about 5°c, with, probably, considerably colder episodes; these results are of importance as database of the oxygen isotope composition of mammal skeletal remains of palaeolithic age. by comparing all the samples from europe, measured up to now, these new data may help the detailed reconstruction of the impact of each climatic event along ns and ew geographic sections. rreeffeerreenncceess ayliffe l.k., chivas a.r. leakey m.g. – 1994. the retention primary oxygen isotope composition of fossil elephant skeletal phosphate. geochim., cosmochim. acta, 5588, 5291-5298. bartolomei g., broglio a., cassoli p., castelletti l., cremaschi m., giacobini g., malerba g., maspero a., peresani m., sartorelli a. and tagliacozzo a. –1992a. la grotte-abri de fumane. un site aurignacien au sud des alpes. preistoria alpina, museo tridentino di scienze naturali, 2288, 131179. bartolomei g., broglio a., cassoli p., cremaschi m., giacobini g., malerba g., maspero a., peresani m. and tagliacozzo a. 1992b. risultati preliminari delle nuove ricerche al riparo di fumane. annuario storico della valpolicella, 9-64. bryant j.d., froelich p.n., showers w.j. and genna b.j. – 1996. biologic and climatic signals in the oxygen isotopic composition of eocene-oligocene equid enamel phosphate. palaeogeogr., palaeoclimatol., 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2001 testo definitivo ricevuto il 19 dicembre 2001 ms. received: october 31, 2001 final text received: december 31, 2001 amq 712 iannucci et al 36,1 75-90.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 36 (1), 2023, 75-90 1. introduction during the quaternary, marked climatic and environmental changes took place at a global scale, most notably affecting meteorological and oceanographic circulations, the intensity of the glacial activity in the northern hemisphere, and the frequency and amplitude of oscillations between cool-arid and warm-humid conditions (shackleton, 1995; flesche kleiven et al., 2002; gibbard et al., 2005; ehlers & gibbard, 2007; etourneau et al., 2010; gibbard & head, 2020). in turn, these changes promoted substantial reorganizations of the large mammal fauna. forty years ago, azzaroli (1983) recognized and named three major “dispersal events” (repenning, 1967, 1980), referring to them as “short periods of rapid intercontinental migrations and faunal replacements” (azzaroli, 1983, p. 117), namely the “elephant-equus event” (between 3.0 and 2.5 ma), the “wolf event” (~1.7 ma), and the “end-villafranchian dispersal event” (~1.0-0.9 ma). in the following years, the proposed timing of these events was further discussed and refined (azzaroli et al., 1988; azzaroli, 1995; gliozzi et al., 1997), eventually correlating the elephantequus event with what is currently recognized as the pliocene-pleistocene transition (~2.6 ma), the wolf event with the gelasian-calabrian transition (~1.8 ma; the pliocene-pleistocene boundary prior to 2009), and the end-villafranchian event with the early-middle pleistocene transition (~0.8 ma). whilst azzaroli (1983) regarded the aforementioned dispersal events as moments of marked faunal renewals and recognized in some cases the gradual character of the associated turnover, the approximate synchronicity between dispersal events and relevant geological transitions exacerbated their geochronological importance. this resulted in a widespread use of the appearance of the “representative” species after which the events were named (e.g., the genus equus for the elephant-equus event) as a stratigraphic datum (see iannucci & sardella, 2023, for discussion). essentially, there are at least two aspects of azzaroli’s dispersal events that resulted in ambiguous applications. first, https://doi.org/10.26382/amq.2023.03 beware of the “wolf event” remarks on large mammal dispersals in europe and the late villafranchian faunal turnover alessio iannucci, beniamino mecozzi, raffaele sardella dipartimento di scienze della terra (paleofactory lab.), università sapienza, roma, italy. corresponding author: a. iannucci <alessio.iannucci@uniroma1.it> abstract: the “wolf event” is a prominent concept in large mammal biochronology of western europe. it was defined in the 1980s as an intercontinental “dispersal event”, best represented by the arrival of a “primitive wolf”, canis etruscus, but also involving other species. the wolf event denoted the late villafranchian faunal turnover, first expressed in italy in the olivola faunal unit. this event was also considered approximately coincident with the pliocene-pleistocene boundary adopted prior to 2009 (~1.8 ma, gelasian-calabrian transition), hence indicating important environmental changes and representing a relevant tool for correlation. whilst it became soon clear that sporadic finds of modern canids (and, to some extent, other species) pre-dated the age assumed for the wolf event, several authors continued to use the term and to associate it to the late villafranchian, referring to the “massive expansion” of the species involved, rather than their first appearance in the european fossil record. several bioevents traditionally included in the wolf event and others that have been considered to occur later are today already documented in middle villafranchian faunas. the “pachycrocuta brevirostris event”, proposed as a replacement term for the wolf event, based on current evidence would be characterized by the arrival in europe of the giant hyena p. brevirostris and panthera gombaszoegensis, and the increase in the documentation of other species traditionally included in the wolf event. however, this does not correspond to a sharp faunal turnover as traditionally envisioned for the wolf event and it is possibly heralded in faunas slightly older than olivola at ~2.0 ma. in other terms, available evidence highlights the rather diachronic nature of large mammal dispersal occurred in the late middle and early late villafranchian (late gelasian, ~2.2–1.8 ma), pushing to critically evaluate the biochronological, paleoecological, and paleobiogeographical significance of each bioevent. for instance, the arrival of hippopotamus in europe is now attested since ~2.2 ma, documenting an african dispersal of a species linked to humid conditions in a context that is generally deemed to denote the spread of open-adapted faunal elements of mainly asian affinities. keywords: biochronology, bioevent, faunal renewal, pleistocene, villafranchian. 76 iannucci a. et al. although named after one or few taxa, these periods of faunal turnover involved, by definition, many species. second, they were envisioned as “short”, but not properly geologically instantaneous intervals. to this list can be added that azzaroli (1983) emphasized the link between faunal and environmental changes, or, in other terms, he inherently included a paleoecological component in the biochronological event. of course, this is not to say that implementations of the dispersal event concept with a meaning that deviate from that used by azzaroli (1983) are necessarily wrong. indeed, as in general for other biochronological terms, concepts, principles, and practices, they are not formally defined within a stratigraphic code, which means that there exist a (legit) variety of approaches among different researchers (e.g., gradstein et al., 1985; lindsay, 2003; palombo & sardella, 2007; palombo, 2009). however, this unavoidably leaves room for ambiguity, most notably when divergent adoptions of a dispersal event are discussed as if referring to the same thing, while different authors might have invested the same term with different meanings. conceptual dichotomies aside, over the years several discoveries have pushed to reconsider the timing of specific bioevents (i.e., those linked to a single taxon), and thus, partly depending on the different acceptances with which azzaroli’s dispersal events have been used, authors opinions diverge as to whether reinterpret, reimagine, or abandon the use of specific dispersal events. the wolf event played a special role in quaternary large mammal biochronology, especially in western europe (fig. 1), given the approximate coincidence between this event (in its original formulation) and the formerly adopted pliocene-pleistocene boundary at ~1.8 ma (i.e., prior to the placement of the pleistocene epoch/series at ~2.6 ma, in 2009; aguirre & pasini, 1985; pillans, 2004; clague, 2006; gibbard & head, 2010; gibbard et al., 2010; head & gibbard, 2015; capraro & maiorano, 2023). here, using the wolf event as a case study, we offer a discussion, partly conceptual, partly factual, on the dispersal of wolf-like canids into europe and on some other specific bioevents currently recognized to have occurred in the late middle and late villafranchian (late gelasian, ~2.2–1.8 ma) that have been the subject of debate and in some instances considered in the framework of the wolf event. 2. the “wolf event” azzaroli (1983) remarked that turnover associated with the wolf event was overemphasized in the italian fossil record due to the lack of middle villafranchian faunas, but he included in the wolf event the arrivals of leptobos etruscus (replacing l. stenometopon), sus strozzii, pachycrocuta brevirostris, and canis etruscus. the latter is the “wolf” after which the event was named. this turnover would correspond to the beginning of the late villafranchian, and to the olivola faunal unit (fu). other groups of canis were considered to appear only in fig. 1 main fossiliferous localities mentioned in this work: 1 fonelas p-1; 2 la puebla de valverde; 3 perrier-les etouaires, rocaneyra; 4 senèze; 5 vialette; 6 saint vallier; 7 oosterschelde; 8 olivola, quercia; 9 valdarno superiore (several localities); 10 montagnola senese; 11 vigna nuova, chiusi basin, torre picchio; 12 monte riccio; 13 bocchignano, castel san pietro; 14 coste san giacomo, fontana acetosa; 15 elis, aetorráchi, hághios demétrios, 16 gerakarou 1. 77 “wolf event” and large mammal dispersal and the proper spread of the group since the beginning of the late villafranchian. further evidence of middle villafranchian canis has piled up in the following decades, some of which perhaps related to wolf-like canids, either deriving from the subsequent tasso fu (azzaroli, 1983). azzaroli et al. (1988) remarked the coincident disappearance of nyctereutes and gazella, the appearance, possibly related to evolutionary changes, of eucladoceros dicranios and dama nestii (currently often referred to ‘pseudodama’, see cherin et al., 2022, and references therein), and the arrival of another species, panthera toscana (today referred to p. gombaszoegensis), alongside the bioevents previously recognized. concerning the latter, however, azzaroli et al. (1988, p. 84) referred to the “massive expansion in europe” of the considered species, rather than their earliest appearance in the fossil record, again leaving room for divergent interpretations. therefore, there are different aspects of azzaroli’s wolf event that need to be critically evaluated based on the available evidence. it is worth considering: first, whether the dispersal of wolf-like canids in europe is coincident with the beginning of the late villafranchian in correspondence of the olivola fu or not; second, how many of the aforementioned bioevents are indeed part of the same “dispersal event”. in the following, these two points are briefly discussed. when azzaroli (1983) schematized the wolf event and placed it in correspondence of the olivola fu, remains of possibly older canis were already known at least from the french site of senèze (martin, 1973), but the chronological consistency of the faunal assemblage recovered from this locality was often doubted (masini & torre, 1990; mazza & rustioni, 1994; rook & torre, 1996). further canid remains were recovered from coste san giacomo (predating olivola and now dated at ~2.2 ma, florindo et al., 2021; coste san giacomo fu) and attributed to canis etruscus by rook & torre (1996), in line with ongoing investigation. rook & torre (1996) also reported the presence of a partial hemimandible of a canid recovered from quercia (near olivola and stratigraphically lower than it; iannucci, 2023), accepted a middle villafranchian age for the canids of senèze, and concluded that the earliest dispersal of modern dogs occurred during the middle villafranchian. nonetheless, rook & torre (1996, p. 499) argued that “the meaning of the “wolf-event” for the beginning of the late villafranchian does not loose its value of “faunal event” in the sense of marked change in faunal assemblages”. in the seminal synthesis on italian biochronology by gliozzi et al. (1997), the status of the wolf event was not directly discussed, but the authors reiterated the first occurrence of wolf-like canids (c. etruscus) in italy from the middle villafranchian of coste san giacomo fig. 2 distribution of canis (a) in the middle villafranchian of western europe: 1 coste san giacomo, fontana acetosa; 2 oosterschelde; 3 roca-neyra; 4 senèze; 5 chilhac 2; 6 saint vallier; 7 quercia; 8 montagnola senese; 9 vigna nuova, torre picchio. silhouettes of canids modified from: iurino et al. (2022; canis etruscus, canis sp.); bartolini lucenti & spassov (2022; canis (x.) lycanoides); wikimedia commons (https://commons.m.wikimedia.org/wiki/file:canis_arnensis_restoration.jpg; canis arnensis). distribution of hippopotamus (b) in the middle villafranchian of western europe: 1 senèze; 2 chiusi basin; 3 castel san pietro; 4 coste san giacomo, fontana acetosa; 5 hághios demétrios, aetorráchi. silhouette of hippopotamus modified from phylopic, by zimices (phylopic.org/image/c2d68ebb-50ec-45f48cd1-6cf52ad02286). new discoveries or reconsiderations of old collections (fig. 2a). two lower incisors assigned to canis sp. were reported by fondi (1972) from montagnola senese, whose fauna has been referred to the coste san giacomo fu (bona et al., 2015). a fragmentary premolar and a portion of a distal metapodial of canis sp. are known from torre picchio (girotti et al., 2003), also referred to the coste san giacomo fu (bona et al., 2015). during the revision of the carnivoran record of saint vallier, argant (2004) identified the presence of a partial neurocranium referable to the genus canis. the locality is customarily biochronologically placed between montopoli and coste san giacomo fus, with estimated ages ranging from 2.5 to 2.0 ma (viret, 1954; azzaroli, 1970, 1977; torre et al., 1992; gliozzi et al., 1997; guérin, 2004; nomade et al., 2014; brugal et al., 2020). reumer & piskoulis (2017) assigned to canis cf. etruscus a mandibular fragmented recovered from the oosterschelde estuary, whose early pleistocene fossil fauna, although resedimented in late pleistocene deposits and collected during dredging activity, is referred to the middle villafranchian, or to ~2.4–2.1 ma (scager et al., 2017). azzarà et al. (2022) described a portion of the axial skeleton of a single individual of canis sp. recovered from the middle villafranchian (coste san giacomo fu) site of vigna nuova, considering it very similar to comparable material of c. etruscus known from olivola (torre, 1967). finally, concerning the long debate on the possibility of age heterogeneity in the faunal assemblage from senèze (see delson et al., 2006), pastre et al. (2015) performed 40ar/39ar datings that constrain the sequence between ~2.2 and 2.09 ma. recently, u-pb dating on volcanic zircons was also applied at senéze, with results providing a mean age of of 2.100 ± 0.029 ma (paquette et al., 2021). an even older record of canis sp. would be that of vialette (heintz et al., 1974), which lacombat et al. (2008) referred to 3.14 ma. however, the attribution of the material and the chronology of the site have been contested. the problems concerning the chronology of the site or, more precisely, the mixing of different faunal elements among those labelled as from vialette in the collection of the musée crozatier (le puy-en-velay), has been commented by several authors (guérin, 2005; van der made et al., 2014; palombo & alberdi, 2017). perhaps the clearest example of chronological heterogeneity is represented by the identification of some remains belonging to late miocene suids, namely assigned to listriodon and cf. “microstonyx” major (van der made 2005; van der made & moullé, 2005), the latter species being more commonly placed in hippopotamodon in recent literature (iannucci et al., 2021a). as for the taxonomic attribution of the canid material to canis, lacombat et al. (2008, p. 67) argued that: “the morphology, the size and the proportions of these remains allow us to exclude genera occurring in the early pliocene”, while böhme et al. (2021) recently suggested it could rather belong to eucyon. on the other hand, böhme et al. (2021) reported material of wolf-like canids from perrier-les etouaires, referring it to 2.78 ma following nomade et al. (2014). this chronology calls for further discussion. nomade et al. (2014) provided this age for pumices of la côte d’ardé, which they considered stratigraphically close to perrier-les etouaires “classical site”. however, as pointed out by iannucci & sardella (2023), this age cannot be accepted uncritically for all the mammal remains recovered from perrier-les etouaires. indeed, it is known that the fauna of perrierles etouaires contains early villafranchian and middle villafranchian species, which originated from layers of different ages (poidevin et al., 1984; palombo & valli, 2004). in any case, following the dating and correlations proposed by nomade et al. (2014) for the entire area of perrier, the fossil findings should be constrained between ~3.1 and 2.6 ma, an age that would be thus enough to make the record of wolf-like canids from perrier-les etouaires reported by böhme et al. (2021) the earliest (excluding vialette) in europe (iannucci & sardella, 2023), although the material has not been described. indeed, the presence of canis aff. etruscus from etouaires was reported by heintz et al. (1974) based on material part of the bravard collection housed in the british museum listed by lydekker (1885, p. 126). however, the material mentioned by lydekker (1885) is possibly from younger deposits at tour-de-boulade, and indeed the author considered it undistinguishable from c. lupus. this view was reaffirmed by torre (1979), who stated that these fossils were of large size, similar to that observed in wolves of the last glaciations (which would correspond to the second part of late pleistocene). marciszak et al. (2023) also reported unpublished material of canis cf. etruscus from węże 2, referring it to 2.9–2.6 ma, also listing further material from poland potentially of middle villafranchian age. in sum, while the evidence for some of the aforementioned findings might not be conclusive, it has long been quite clear that the arrival of wolf-like canids in europe is at least as early as the coste san giacomo fu (middle villafranchian), and there is further putative evidence that would suggest an even older age. it is worth reiterating that the occurrence of wolf-like canids already in the middle villafranchian did not discourage several authors to continue using the wolf event to refer to the late villafranchian faunal turnover as a whole, emphasizing the increase in the abundance of wolf-like canids, rather than their earliest appearance in the fossil record (e.g., rook & torre, 1996). this late villafranchian “massive expansion”, as it has been referred to by azzaroli et al. (1988) and generally agreed in subsequent research (e.g., gliozzi et al., 1997), is well documented in italy, for instance by historical samples from olivola and the upper valdarno, and by the abundant record of pantalla (cherin et al., 2013, 2014). 3. the “hippo event” the earliest dispersal of hippopotamus in europe was not among the bioevents listed by azzaroli (1983) as part of the wolf event, but we consider particularly appropriate to discuss it here as there is now evidence of late middle villafranchian (late gelasian) hippopotamuses from several european localities, some of which also yielded early canis (fig. 2b). in particular, a fragmentary incisor of hippopotamus sp. is known from coste san giacomo (bellucci et al., 2012, 2014; sardella, 2012). the age of the fossil horizon was consid 78 iannucci a. et al. chian hippopotamus in europe (dated at ~2.2 ma), but it is not the only. cassoli & segre naldini (1984) listed hippopotamus sp. among the faunal remains recovered from fontana acetosa, like coste san giacomo, another locality of the anagni basin in central italy. the authors remarked the similar nature of the fossiliferous levels of coste san giacomo and fontana acetosa, yellow sands, although somewhat more clayey at fontana acetosa, but did not exclude the possibility of a slightly younger age for the latter site. the presence of hippopotamus seemed indeed at odds with the then accepted first appearance of the species in the tasso fu (azzaroli, 1983). when bellucci et al. (2012) recognized the presence of hippopotamus at coste san giacomo, they also accepted the correlation between the two sites, although the fauna of fontana acetosa would be in need of a systematic study to clarify the biochronological value of the species reported. during the revision of the fossil collection stored at faculté des sciences de l'université claude bernard, lyon i, a first phalange (fsl 211082), previously ascribed to equus sp., was attributed to hippopotamus cf. antiquus by mazza & rustioni (1994). the fossil was recovered from domeyrat, one of the toponyms generally considered as part of senèze locality. the presence of hippopotamuses at senèze was previously listed by jung (1946) and bout (1960), but then excluded from subsequent faunal lists (e.g., heintz et al., 1974), possibly due the supposedly later arrival of hippopotamus in europe. it seems conceivable that reports older than the work by mazza & rustioni (1994) were based on further undescribed material and, in any case, even after that mazza & rustioni (1994) reaffirmed the occurrence of hippopotamuses at senèze, these were seldom considered in subsequent biochronologic schemes (but see arribas et al., 2009), likely due to the uncertainty on the chronology of the locality (see previous section above). nonetheless, as discussed in the previous section, several radiometric estimates now constrain the succession of senèze at ~2.2–2.1 ma (nomade et al., 2014; pastre et al., 2015; paquette et al., 2021), approximately coeval with coste san giacomo. several findings of middle villafranchian hippopotamuses are known from the area of elis, in greece, as recently reviewed by athanassiou (2022). these remains include: dentognathic material described by thenius (1955), which according to athanassiou (2022) can be considered of earliest pleistocene age owing to invertebrate biochronology; further osteological and dental finds mentioned by symeonidis & theodorou (1986) from hághios demétrios; a juvenile fragmented cranium from aetorráchi (reimann & strauch, 2008). other hippopotamus remains attributed to h. antiquus were recovered from the chiusi basin (cuscani politi, 1966, 1971; mazza, 1995; pandolfi & petronio, 2015). an accompanying faunal assemblage was also reported by pandolfi & petronio (2015), including gazella sp., axis (=‘pseudodama’) cf. nestii and eucladoceros sp., although not described and made up of surface finds, the authors referred it to the coste san giacomo or olivola fus. the occurrence of gazella would point towards the former, considering that the taxon is not recorded in italian localities younger than the coste san ered around 2.1 ma by bellucci et al. (2014), based on magnetostratigraphy, pollen, and small mammals, and further refined at ~2.2 ma by florindo et al. (2021). bellucci et al. (2012) firstly identified the specimen as belonging to a hippopotamus, although a more precise taxonomic attribution is clearly precluded by the scanty nature of the sample. sardella et al. (2018) clarified that the hippopotamus incisor from coste san giacomo was not collected during systematic excavations but is part of the 1980s field collection, causing some authors to doubt the age of the finding (marra et al., 2018; martino & pandolfi, 2022). however, field activities and excavations at coste san giacomo co-directed by one of us (rs) have pointed out that the vertebrate assemblage comes from a single fossiliferous level, from which the old collections can also be related (bellucci et al., 2012, 2014; bona et al., 2015; strani et al., 2015; palombo et al., 2017). it is worth noting that the fauna of coste san giacomo has long been considered a homogeneous assemblage, besides representative of the homonymous fu, the latest of the middle villafranchian (gliozzi et al., 1997). the reason why the hippopotamus record of coste san giacomo has often been considered controversial (e.g., martínez-navarro et al., 2015; pandolfi & petronio, 2015) seems rather contingent. traditionally, the earliest occurrence of hippopotamus in italy was placed in the tasso fu, based on several historical findings from the upper valdarno (nesti, 1820; leonardi, 1947; azzaroli, 1977; gliozzi et al., 1997). napoleone et al. (2003) suggested that the hippopotamuses might be of a younger age than that of the rest of the main upper valdarno fauna, considering the lack of their remains among those collected during modern excavations in the area. this possibility was also previously evoked by faure (1985) and mazza (1991). it is worth noting that most of the fossils from the upper valdarno is part of historical collections gathered at least since the nineteenth century (rook et al., 2013). moreover, the absence of hippopotamus remains from certain deposits might also be related to their ecological requirements, namely their sensitivity to the presence and amount of water (mazza & bertini, 2013). martínez-navarro (2004, 2010) and rook & martínez-navarro (2010), following the suggestion of napoleone et al. (2003) on the younger age of the upper valdarno hippopotamuses, remarked that consequently venta micena yielded the oldest european record of hippopotamus antiquus (although other older records were known, e.g., that from monte riccio, mazzini et al., 2000). mazza & bertini (2013, p. 195) also argued that “the first certified occurrence of hippopotamus antiquus is from the early pleistocene locality of venta micena”, but not excluding the occurrence of earlier findings of uncertain taxonomic status (e.g., the authors quoted fontana acetosa). in brief, the finding of the hippopotamus of coste san giacomo was published at a time when some researchers were hypothesizing a later chronology for the arrival of hippopotamus into europe (bellucci et al., 2012; sardella, 2012). this was, however, not universally accepted (e.g., arribas et al., 2009). in general, the finding of coste san giacomo represents the earliest occurrence of a middle villafran 79 “wolf event” and large mammal dispersal 80 giacomo fu (masini et al., 2013; bellucci & sardella, 2015). the scheme proposed by azzaroli (1983) featured the first appearance of hippopotamus in the tasso fu, which has been most influential in the biochronological correlation of several faunas. the implications for the inferred age of three localities are especially worth mentioning here, recognizing the presence of hippopotamuses in europe already in the middle villafranchian, namely castel san pietro, bocchignano, and monte riccio (all in italy). at castel san pietro, several fossil mammal remains were collected and partly described during the nineteenth century, as a by-product of the exploitation of a lignite mine (tuccimei, 1889a, 1889b, 1891, 1898; maxia 1949). the presence of hippopotamuses from the area of castel san pietro was reported by meli (1882) and tuccimei (1891). pandolfi et al. (2017) carried out a revision of the scanty mammal remains, and further analysis based on ostracods and paleofloristic remains. their results converged to suggest a gelasian deposition of the lignite beds of castel san pietro (~2.5–1.8 ma) in a warm-humid and forested area. concerning the hippopotamuses, the authors casted doubt on their association with the rest of the fauna and commented that the whereabouts of the material are unknown. marra et al. (2018) argued for the presence of two different assemblages at castel san pietro, the older with anancus arvernensis, the younger with h. antiquus. nonetheless, the cooccurrence of a. arvernensis and hippopotamus cannot be ruled out and, if confirmed, would point to a reference to the coste san giacomo fu, as exemplified by the record from the reference fauna of this fu (bellucci et al., 2014). bocchignano is another site whose hippopotamuses remains have been considered indicative of faunal mixing (marra et al., 2018). the fossil remains recovered from the site were reported and described by tuccimei (1889b, 1891, 1893). kotsakis (1988) revised the taxonomic attribution of the arvicoline rodents, referring them to mimomys polonicus or mimomys pliocaenicus. recently, marra et al. (2018) suggested the presence of two different assemblages, the oldest with mimomys (saint vallier to olivola fus), the youngest with hippopotamus (tasso fu). as in the case of castel san pietro, the cooccurrence of the two species is arguably conceivable (if the arvicoline belongs to m. pliocaenicus) and in agreement with a correlation of the fauna with the coste san giacomo or olivola fus (bellucci et al., 2014; bona et al., 2015). unlikely of middle villafranchian age but worth of consideration here is the diverse fauna of monte riccio, including prolagus sp., cf. mammuthus meridionalis, sus strozzii, h. antiquus, leptobos cf. etruscus, procapreolus sp., eucladoceros ctenoides, axis (= ‘pseudodama’) nestii, stephanorhinus cf. etruscus, equus stenonis, vulpes cf. alopecoides, canis etruscus, and megantereon cultridens (mazzini et al., 2000). indeed, this assemblage has been referred to the tasso fu due to the presence of h. antiquus (mazzini et al., 2000; marra et al., 2018), while croitor (2012) suggested a correlation with the olivola fu or even a slightly older age, based on the ruminants. in brief, there is evidence for a middle villafranchian dispersal of hippopotamus into europe ~2.2–2.1 ma, partly documented by remains collected from some of the localities that have been also important to recognize an earlier (than what proposed by azzaroli, 1983) arrival of modern canids, namely coste san giacomo and senèze. the “hippo event” is of paleobiogeographic and paleoecological relevance, in that it testifies to the dispersal into europe of a taxon of clear african origin and of distinct ecology. indeed, though not necessarily limited to warm environments, remains of hippopotamus are indicative of the presence of permanent water bodies and humid climatic conditions (candy et al., 2006, 2010; bellucci et al., 2012; russo ermolli et al., 2010; mazza & bertini, 2013; adams et al., 2022). moreover, morphological considerations and dietary proxies suggest that h. antiquus was even more adapted to an aquatic lifestyle than h. amphibius (palmqvist et al., 2003, 2008; adams et al., 2022). as mentioned previously, perhaps these ecological requirements explain the patchy distribution of middle and late villafranchian occurrences of hippopotamuses in europe, whereas since ~1.5 ma hippopotamus become a common element of the european terrestrial ecosystems (caloi et al., 1980; faure, 1985; kahlke, 1989, 2001; mazza, 1991, 1995; kahlke et al., 2011; van der made et al., 2017; fidalgo et al., 2021; mecozzi et al., 2021; adams et al., 2022; strani et al., 2022). in this regard, it is worth mentioning that paleoenvironmental reconstruction based on ungulate dietary adaptations attest the presence of humid subtropical-like environments at coste san giacomo (strani et al., 2015), whereas comparable analyses point to the occurrence of more open conditions at olivola, where no hippopotamuses are known (strani et al., 2018). 4. other bioevents apart from the arrival of c. etruscus, several other bioevents were listed by azzaroli (1983) and azzaroli et al. (1988) as part of the wolf event, and others have been proposed and discussed over the years. in particular, azzaroli (1983) listed l. etruscus, s. strozzii, and p. brevirostris. the giant hyena is the only species of this contingent whose first appearance in europe is still related to the late villafranchian faunal turnover (see section 5). indeed, while the “massive expansion” (azzaroli et al., 1988) of l. etruscus and s. strozzii can still be placed in correspondence of olivola and tasso fus, remains of both species are already documented in middle villafranchian faunas (masini & sala, 2007; cherin et al., 2018, 2019; iannucci et al. 2020; sorbelli et al., 2023). isolated dental remains of large-sized suids, which are generally referred to s. strozzii, are known from several middle villafranchian sites, including saint vallier, valdeganga ii, coste san giacomo, quercia, and vigna nuova, among others, and the locality of senèze yielded an almost complete skeleton (schaub, 1943; mein et al., 1978; azzaroli et al., 1988; faure, 2004; cherin et al., 2018; iannucci et al., 2020; azzarà et al., 2022; iannucci, 2023). remains of l. etruscus are also known from senèze (masini, 1989; cherin et al., 2019). moreover, the iannucci a. et al. debate surrounding the taxonomy and evolutionary relationships of middle and late villafranchian leptobos spp., the presence of chronologically overlapping different lineages, and the possible appearance per-evolution (rather than per-dispersal) of the species in europe, clearly push to exercise caution in biochronological correlations (cherin et al., 2019; sorbelli et al., 2023). objective difficulties in the attribution of isolated remains and disagreement on the taxonomy also complicate identifying and resolving the timing of specieslevel event of eucladoceros spp. and ‘pseudodama’ spp. between the middle and late villafranchian, as reflected by the many samples left in open taxonomy (e.g., bellucci et al., 2014; pandolfi & petronio, 2015; azzarà et al., 2022). apart from evolutionary changes in the aforementioned cervid lineages, azzaroli et al. (1988) also mentioned the extinctions of nyctereutes and gazella. both are still considered typical middle (or even early) middle villafranchian taxa, but at least gazella is present in some faunas that could be regarded as late villafranchian or as transitional between the middle and the late villafranchian (e.g., fonelas p-1 and gerakarou 1, see section 5). the arrival of the caprinae procamptoceras brivatense was listed among the bioevents characterizing the late villafranchian turnover by gliozzi et al. (1997), based on its occurrence at olivola (azzaroli, 1950), but the species is already present in senèze and tentatively listed in older faunas (heintz et al., 1974; palombo & valli, 2004). in general, the record of p. brivatense is arguably too patchy to be stressed in a biochronological context, although this might change with further discoveries. the arrival of panthera gombaszoegensis was added by azzaroli et al. (1988) among the bioevents characterizing the wolf event. the first appearance of the species in the italian fossil record is still in the olivola fu (ficcarelli & torre, 1968; gliozzi et al., 1997; palombo, 2009). the locality of gerakarou 1 also yielded remains of the species (koufos, 1992, 2014). the occurrence of the species at la puebla de valverde, calibrated between feni and olduvai subchrons at ~2.12–1.92 ma and generally considered close in age to but more progressive than saint vallier (sinusía et al., 2004; cuccu et al., 2023), was listed by madurell-malapeira et al. (2014), but not reported by kurtén & crusafont-pairó (1977) and cuccu et al. (2023). when azzaroli (1983) discussed the wolf event, c. etruscus was the only modern canid whose arrival was correlated with the olivola fu, while the first appearance of canis arnensis and canis falconeri was placed in the following tasso fu. both species are now already documented in middle villafranchian faunas of western europe. recently, bartolini lucenti & spassov (2022) substantially extended the chronological range of the wild dog canis (xenocyon) falconeri, referring to this taxon a mandible from roca-neyra (~2.6 ma), which suggests a patchy distribution of the species in europe since the beginning of the middle villafranchian. the earliest record of c. arnensis known to date is from senèze, based on the available dating for the site and the generally accepted synonymy between c. arnensis and c. senezensis (brugal & boudadi-maligne, 2011; bartolini lucenti & rook, 2016). several early occurrences of canis sp. listed previously (see section 2) might also belong to species other than c. etruscus (fig. 2a). 5. the “pachycrocuta brevirostris event” and the beginning of the late villafranchian the term “pachycrocuta brevirostris event” or similar expressions have been sporadically used since the 1990s, e.g., by masini & torre (1990; “pliohyaena brevirostris event”), torre et al. (1992; “pachycrocuta brevirostris dispersal event”), palombo et al. (2008; “pachycrocuta event”), but it is only with the work of martínez-navarro (2010) that this concept acquired the meaning of a replacement term for azzaroli’s wolf event. as mentioned in section 2, the evidence of middle villafranchian remains of modern canids alone did not push other researchers to abandon the use of the wolf event earlier, mainly emphasizing the increase in abundance of wolf-like canids, rather than their first appearance in the european fossil record (azzaroli et al., 1988; rook & torre, 1996). sardella & palombo (2007) reviewed the concept of the wolf event and analyzed carnivoran faunas of western europe around the old pliocene-pleistocene boundary (aguirre & pasini, 1985; see pillans, 2004 and clague, 2006), i.e., prior to the provisions adopted in 2009, following which the base of the pleistocene epoch/series was placed at ~2.6 ma (gibbard & head, 2010; gibbard et al., 2010; head & gibbard, 2015). sardella & palombo (2007) argued that, considering the carnivorans, the wolf event includes several diachronic bioevents, such as the dispersals of different canids, panthera, and pachycrocuta. the latter, involving the giant hyena pachycrocuta brevirostris, was regarded as the most representative dispersion in europe. according to iannucci et al. (2021b), the earliest calibrated occurrence of p. brevirostris is likely from fonelas p-1, placed between feni and olduvai subchrons, hence between ~2.12 and 1.92 ma (arribas et al., 2009). some uncertainty persists, however, considering that the taxonomic identification is based on few elements of the deciduous dentition (arribas & garrido, 2008), with only one tooth actually exceeding the biometric range known for pliocrocuta perrieri, a species also present in the site (iannucci et al., 2021b). like fonelas p-1, the fauna of gerakarou 1 is either referred to as middle or late villafranchian (or as transitional), especially due to the cooccurrence of p. brevirostris and gazella (koufos, 1992; konidaris et al., 2021). in italy, gazella is not recorded after the coste san giacomo fu (masini et al., 2013; bellucci & sardella, 2015) and indeed its disappearance was listed among the bioevents characterizing the late villafranchian faunal turnover (azzaroli et al., 1988; gliozzi et al., 1997). in france, it could have become locally extinct even earlier, as it is already absent in senèze and other faunas usually considered of similar age (heintz et al., 1974; palombo & valli, 2004). assuming that this absence is not due to the paucity of the fossil record and/or biased by the environmental preferences of gazella, the association of 81 “wolf event” and large mammal dispersal 82 gazella and p. brevirostris suggests an age intermediate between coste san giacomo and olivola fus. this implies a certain degree of subjectivity in referring faunas in which such association is documented, like fonelas p-1 and gerakarou 1, as to middle or late villafranchian. we argue that these faunas could simply be considered transitional between biochronological units traditionally recognized (arribas et al., 2009; konidaris et al., 2021). this is probably the best choice to minimize inconsistency in current research and with previous studies. the fauna of olivola includes p. brevirostris (ficcarelli & torre, 1970) but it is not directly dated. paleomagnetic investigations carried out at poggio rosso, allowed to correlate this latter locality within the olduvai subchron at ~1.92–1.77 ma (napoleone et al., 2001, 2003; mazza et al., 2004). the fauna of poggio rosso has been considered transitional between olivola and tasso fus (gliozzi et al., 1997), or in other terms it cannot be unequivocally ascribed to one of the two fus, but in any case provides indirect constraints for both. the giant hyena p. brevirostris is documented by direct skeletal evidence in ~60 localities across europe (iannucci et al., 2021b), a number that would likely increase taking into account indirect evidence (e.g., coprolites, gnawing marks) and reports in open taxonomy. actually, roughly coeval early occurrences are known from both sides of eurasia at ~2.0 ma (arribas et al., 2009; liu et al., 2021; iannucci et al., 2021b). the giant hyena is a species that played an important role as a taphonomic agent and has been the subject of much research focused on investigating its potential relationships with other carnivorans and early hominins dispersing out of africa (turner & antón, 1996; palmqvist et al., 2011; espigares et al., 2013; madurell-malapeira et al., 2017; iannucci et al., 2021b). this explains why p. brevirostris has been considered a representative species of the late villafranchian faunal turnover (palombo & sardella, 2007; martínez-navarro, 2010). the earliest material referred to pachycrocuta sp. is from the pliocene of east africa, but african remains of pleistocene age are only known from the south of the continent, possibly indicating that pachycrocuta did not survive long in east africa (werdelin, 1999; werdelin & lewis, 2008). pachycrocuta brevirostris is thought to derive from a large-sized population of pliocrocuta perrifig. 3 selected biochronological schemes and mammal ranges proposed over the years (a) and the updated scheme adopted in this work (b). saint vallier has often been placed in italics to emphasize that it is not an italian site. silhouettes modified from: iurino et al. (2022; canis etruscus); iannucci et al. (2021, pachycrocuta brevirostris); phylopic, by zimices (phylopic.org/image/c2d68ebb-50ec-45f48cd1-6cf52ad02286, hippopotamus). iannucci a. et al. eri, most likely in asia, where transitional samples are known (qiu et al., 2004; iannucci et al., 2021b). in western eurasia, remains assigned to pachycrocuta brevirostris and pliocrocuta perrieri are jointly known from fonelas p-1, gerakarou 1, and dmanisi (collectively ~2.1–1.8 ma; koufos, 1992, 2014; vekua, 1995; lordkipanidze et al., 2007; arribas et al., 2009; iannucci et al., 2021b). the two species share an overall similar morphology in many respects and, especially dealing with isolated remains, attributions often relied on biometric comparisons. as the often-evoked “giant” size of p. brevirostris suggests, this approach is generally accepted, but considering the close relationship between the two species and the many implications associated to the appearance of p. brevirostris, it should be accompanied by some reflection (see iannucci et al., 2022b, for discussion). 6. discussion and conclusions azzaroli (1983) named “wolf event” the faunal turnover associated to the beginning of the late villafranchian, coinciding with the olivola fu. this was also roughly coincident with the old (i.e., prior to 2009) plio-pleistocene boundary at ~1.8 ma. initially, this event was considered to document the first appearance in the european fossil record of canis etruscus (the “wolf”, hence the name) and other large mammals (leptobos etruscus, sus strozzii, and pachycrocuta brevirostris), but soon modified to include the “massive expansion” of the considered species and other bioevents (azzaroli et al., 1988, p. 84). the latter adjustment was a good compromise between the need not to disregard occurrences of the considered species potentially older than olivola (but at the time of doubtful chronology or taxonomic attribution, like those from senèze), and the intention of maintaining the reference role of the olivola fu. however, this definition left room for different interpretations. it is now clear that several bioevents traditionally included in the wolf event and others that have been considered to occur later are conversely already documented in middle villafranchian faunas, most notably the arrival in europe of modern canids, but also of s. strozzii and hippopotamus, among others (fig. 3). if a single species has to be taken as representative of the late villafranchian faunal turnover, the best candidate based on the current evidence is the giant hyena pachycrocuta brevirostris (sardella & palombo, 2007; palombo et al., 2008; martínez-navarro, 2010; iannucci et al., 2021b). pachycrocuta brevirostris is indeed the only species among those initially listed by azzaroli (1983) as part of the wolf event whose first appearance in the european fossil record is still coincident with the beginning of the late villafranchian at the olivola fu, and its occurrences are abundant across eurasia. the first appearance in the european fossil record of panthera gombaszoegensis (added in the wolf event as an accompanying species by azzaroli et al., 1988), is also documented at that time. however, the faunas fonelas p-1 (spain) and gerakarou 1 (greece) contains pachycrocuta brevirostris in association with gazella, a “typical” middle villafranchian taxon (actually a holdover of even older faunas) that is not documented in italy after the coste san giacomo fu (last fu of the middle villafranchian, older than olivola) (bellucci & sardella, 2015). gerakarou 1 includes also panthera gombaszoegensis. therefore, even the arrival of pachycrocuta brevirostris and panthera gombaszoegensis somewhat anticipates the chronology previously assumed. moreover, the beginning of the late villafranchian does not correspond to a sharp faunal turnover as traditionally envisioned for the wolf event. current evidence highlights the rather diachronic nature of large mammal dispersal occurred in the late middle and early late villafranchian (late gelasian, ~2.2–1.8 ma). in this regard, it would be arguably better avoiding naming this time-averaged phenomenon after a single species. here, we dedicated space to discuss the “hippo event” (section 3), as we think that this case eloquently speaks for the need of critically evaluating the biochronological, paleoecological, and paleobiogeographical significance of each bioevent. indeed, the presence of hippopotamus in europe is now attested since ~2.2 ma, documenting an african dispersal of a species linked to humid conditions in a context that is generally deemed to denote the spread of open-adapted faunal elements of mainly asian affinities. however, this bioevent was once considered younger than ~1.8 ma and placed in the tasso fu (azzaroli, 1983; gliozzi et al., 1997). consequently, the presence of hippopotamus at coste san giacomo and senèze was perceived at odds with a middle villafranchian age and engendered ideas of mixing with substantially younger faunas, which are, however, not supported by available dating and field evidence (delson et al., 2006; bellucci et al., 2014; palombo et al., 2017; paquette et al., 2021). several other faunas have been considered mixed or younger than they really are due to the presence of hippopotamus, including, for instance, castel san pietro, bocchignano, and to some extent monte riccio (e.g., marra et al., 2018). it might be argued that since the arrival of many species once considered to indicate the beginning of the late villafranchian is now recognized to be older, then the passage between the middle and late villafranchian could be moved back as well. however, such an approach would be inconsistent with a huge body of previous research in which the beginning of the late villafranchian is typified by the olivola fu, and hence it would be unavoidably ambiguous. moreover, while it is true that the arrivals of many species traditionally included in the wolf event are now already recorded in middle villafranchian faunas, their “massive expansion” (sensu azzaroli et al., 1988) can still be correlated with the olivola fu. this is the case of leptobos etruscus, sus strozzii, and not least canis etruscus. we argue that the earliest occurrence of pachycrocuta brevirostris and panthera gombaszeogensis heralds the late villafranchian faunal turnover, which is then best expressed by the increase in the documentation of the other species. to minimize inconsistent approaches, “transitional” faunas like fonelas p-1 and gerakarou 1 could be simply referred to as such. in general, resolving the exact timing of large mammal bioevents in the late gelasian is complicated by the paucity of middle villafranchian localities, as already 83 “wolf event” and large mammal dispersal 84 pointed out by azzaroli (1983). moreover, of the two most important large mammal middle villafranchian faunas postdating the montopoli fu listed in the synthesis of gliozzi et al. (1997), namely those of collepardo and coste san giacomo, only the correlation of the latter has been confirmed (bellucci et al., 2012, 2014; bona et al., 2015). conversely, although the fauna of collepardo was initially considered close in age to saint vallier (gliozzi et al., 1997), it is now recognized as markedly older than the french site and referred to the triversa fu (early villafranchian; bellucci et al., 2019; iannucci et al., 2022a). on the other hand, a huge number of localities, more or less abundant in terms of fossil remains, including mainly either sporadic (i.e., not coming from systematic excavations) and/or historical findings, have yielded early pleistocene large mammal faunas. as shown by the recent case of vigna nuova (azzarà et al., 2022), proper examinations of these samples might reveal further middle villafranchian faunas simply not recognized as such. acknowledgements we are thankful to d.a. iurino and f. strani for discussion and support. comments and suggestions received during the revision of this manuscript from the reviewers were appreciated. this work was funded by sapienza university of rome grandi scavi 2021 (grant no: sa12117a87bc3f0a) and grandi scavi 2022 (grant no: sa1221816893e2ab) to rs; sapienza university of rome “progetti per avvio alla ricerca tipo 1 anno 2020” (grant no: ar120172b7d44b9e) to ai; sapienza university of rome “progetti per avvio alla ricerca tipo 2 anno 2022” (grant no: ar222181333c1b88) and “contributi premiali per i ricercatori e assegnisti di ricerca per rafforzarne la condizione professionale e potenziare il sistema della ricerca del lazio” call proposal of the lazio region (de g05411, 05/05/2022) to bm. references aguirre e., pasini g. 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(1996) the wolf-event in western europe and the beginning of the late villafranchian. neues jahrbuch für geologie und paläontologie-monatshefte, 1996(8), 495-501. rook l., martínez-navarro b. (2010) villafranchian: the long story of a plio-pleistocene european large mammal biochronologic unit. quaternary international, 219, 134-144. rook l., croitor r., delfino m., ferretti m.p., gallai g., pavia m. (2013) the upper valdarno pliopleistocene vertebrate record: an historical overview, with notes on palaeobiology and stratigraphic significance of some important taxa. italian journal of geosciences, 132(1), 104-125. russo ermolli e., sardella r., di maio g., petronio c., santangelo n. (2010) pollen and mammals from the late early pleistocene site of saticula (sant'agata de'goti, benevento, italy). quaternary international, 225(1), 128-137. sardella r. (2012) evidence of hippopotamus remains in the middle villafranchian faunal assemblages of anagni basin (central italy): evidence for an early dispersal of the genus in europe. quaternary international, 279-280, 427. sardella r., palombo m.r. (2007) the pliocenepleistocene boundary: which significance for the so called “wolf event”? evidences from western europe. quaternaire, 18, 65-71. sardella r., bellucci l., bona f., cherin m., iurino d.a., rook l. (2018) before and after the earliest homo dispersal in europe: evidence from the early pleistocene sites of the italian peninsula. comptes rendus palevol, 17(4-5), 287-295. scager d.j., ahrens h.j., dieleman f.e., van den hoek ostende l.w., de vos j., reumer j.w.f. (2017) the kor & bot collection revisited, with a biostratigraphic interpretation of the early pleistocene oosterschelde fauna (oosterschelde estuary, the netherlands). deinsea, 17, 16-31. schaub s. (1943) die oberpliocaene säugetierfauna von senèze (haute-loire) und ihre verbreitungsgeschichtliche stellung. eclogae geologicae helvetiae, 36, 270-289. shackleton n.j. (1995) new data on the evolution of pliocene climatic variability. in: palaeoclimate and evolution with emphasis on human origins (ed. by vrba e.s., denton g.h., patridge t.c., burckle l.h.), yale university press, london, 242-248. sinusía c., pueyo e.l., azanza b., pocoví a. (2004) datación magnetoestratigráfica del yacimiento paleontológico de la puebla de valverde (teruel). geotemas, 6(4), 339-342. sorbelli l., cherin m., kostopoulos d.s., sardella r., mecozzi b., plotnikov v., prat-vericat m., azzarà b., bartolini-lucenti s., madurell-malapeira, j. (2023) earliest bison dispersal in western palearctic: insights from the eobison record from pietrafitta (early pleistocene, central italy). quaternary science reviews, 301, 107923. strani f., demiguel d., sardella r., bellucci l. (2015) paleoenvironments and climatic changes in the italian peninsula during the early pleistocene: evidence from dental wear patterns of the ungulate community of coste san giacomo. quaternary science reviews, 121, 28-35. strani f., demiguel d., sardella r., bellucci l. (2018) resource and niche differentiation mechanisms by sympatric early pleistocene ungulates: the case study of coste san giacomo. quaternary international, 481, 157-163. strani f., bellucci l., iannucci a., iurino d.a., mecozzi b., sardella r. (2022) palaeoenvironments of the mis 15 site of cava di breccia-casal selce 2 (central italian peninsula) and niche occupation of fossil ungulates during middle pleistocene interglacials. historical biology, 34(3), 555-565. symeonidis n.k., theodorou g.e. (1986) new localities with fossil hippopotamus in northwestern peloponnese. annales géologiques des pays helléniques, 33, 51-67. thenius e. (1955) hippopotamus aus dem astien von elis (peloponnes). annales géologiques. des pays helléniques, 6, 206-212. 89 “wolf event” and large mammal dispersal torre d. (1967) i cani villafranchiani della toscana. palaeontographia italica, 63, 113-138. torre d. (1979) the ruscinian and the villafranchian dogs of europe. bollettino della società paleontologica italiana, 18(2), 162-165. torre d., ficcarelli g., masini f., rook l., sala b. (1992) mammal dispersal events in the early pleistocene of western europe. courier forschungsinstitut senckenberg, 153, 51-58. tuccimei g. (1889a) alcune recenti osservazioni sul villafranchiano della sabina bollettino della società geologica italiana, 8, 566-568. tuccimei g. (1889b) il villafranchiano nelle valli sabine e i suoi fossili caratteristici. bollettino della società geologica italiana, 8, 95-131. tuccimei g. (1891) alcuni mammiferi fossili delle provicie umbra e romana. memorie della pontificia accademia dei nuovi lincei, 7, 89-152. tuccimei g. (1893) resti di arvicola nel pliocene lacustre della sabina. memorie della pontificia accademia dei nuovi lincei, 9, 35-45. tuccimei g. (1898) sopra alcuni cervi pliocenici della sabina e della provincia di roma. memorie della pontificia accademia dei nuovi lincei, 14, 33-55 turner a., antón m. (1996) the giant hyaena pachycrocuta brevirostris (mammalia, carnivora, hyaenidae). geobios, 29, 455-468. van der made j. (2005) le pliocène moyen, le villafranchien inférieur. la faune du velay vers 3 millions d’années. cf. “microstonyx” major. in: les grands mammifères fossils du velay. les collections paléontologiques du plio-pléistocène du mesée crozatier, le puy-en-velay (ed. by lacombat f.), phil’ print, yssingeaux, 58-59. van der made j., moullé p.e. (2005) le pliocène moyen, le villafranchien inférieur. la faune du velay vers 3 millions d’années. in: les grands mammifères fossils du velay. les collections paléontologiques du plio-pléistocène du mesée crozatier, le puy-en-velay (ed. by lacombat f.), phil’ print, yssingeaux, 56-57. van der made j., stefaniak k., marciszak a. (2014) the polish fossil record of the wolf canis and the deer alces, capreolus, megaloceros, dama and cervus in an evolutionary perspective. quaternary international, 326, 406-430. van der made j., rosell j., blasco r. (2017) faunas from atapuerca at the early-middle pleistocene limit: the ungulates from level td8 in the context of climatic change. quaternary international, 433, 296-346. vekua a. (1995) die wirbeltierfauna des villafranchium von dmanisi und ihre biostratigraphische bedeutung. jahrbuch des römisch-germanischen zentralmuseums mainz, 42, 77-180. viret j. (1954) le loess à bancs durcis de saint-vallier (drôme) et sa faune de mammifères villafranchiens. nouvelles archives du muséum d’histoire naturelle de lyon, 4, 1-200. werdelin l. (1999) pachycrocuta (hyaenids) from the pliocene of east africa. paläontologische zeitschrift, 73, 157-165. werdelin l., lewis m.e. (2008) new species of crocuta from the early pliocene of kenya, with an overview of early pliocene hyenas of eastern africa. journal of vertebrate paleontology, 28, 11621170. ms. received: february 10, 2023 revised: march 18, 2023 accepted: march 19, 2023 available online: march 29, 2023 90 iannucci a. et al. impaginato moro aannaalliissii ppaalleeoossiissmmoollooggiicchhee lluunnggoo llaa ffaagglliiaa ddeell mm.. mmaarriinnee ((aallttaa vvaallllee ddeellll’’aatteerrnnoo)):: rriissuullttaattii pprreelliimmiinnaarrii mmaarrccoo mmoorroo11,, vviittttoorriioo bboossii22,, ffaabbrriizziioo ggaallaaddiinnii33,, ppaaoolloo ggaallllii22,, bbiiaaggiioo ggiiaacccciioo33,, ppaaoolloo mmeessssiinnaa33,, aannddrreeaa ssppoossaattoo33 1ingv, istituto nazionale di geofisica e vulcanologia, roma (e-mail: moro@ingv.it) 2ssn, servizio sismico nazionale, roma (e-mail: vittorio.bosi@serviziosismico.it, paolo.galli@serviziosismico.it) 3cnr, istituto di geologia ambientale e geoingegneria, sez. di roma-tor vergata, roma (e-mail: f.galadini@igag.cnr.it, p.messina@igag.cnr.it, b.giaccio@igag.cnr.it, a.sposato@igag.cnr.it) riassunto il versante sudoccidentale del m. marine è caratterizzato da una faglia normale ad andamento nw-se, ritenuta responsabile della formazione del bacino intermontano dell’alto aterno. l’area è stata interessata dal terremoto del 2 febbraio 1703 (me=6.7). nel corso delle indagini per la realizzazione di una "cartografia geologica prototipale" sono state individuate alcune scarpate di faglia poste alla base del m. marine, con direzione wnw-ese, da ricondurre all'attività recente della faglia. l'identificazione delle scarpate di faglia ha suggerito di avviare un'analisi paleosismologica nell'area. in particolare, è stata realizzata una trincea attraverso una delle scarpate. i risultati ottenuti hanno evidenziato l'occorrenza di un minimo di cinque eventi di dislocazione nell’ambito degli ultimi ca. 15.000 anni, il più recente dei quali è probabilmente da legare al terremoto del febbraio 1703, come evidenziato dalla presenza di colluvi storici fagliati e delle evidenze storiche relative agli effetti geologici del terremoto nell'area investigata. gli studi paleosismologici hanno fornito maggiori vincoli sull’ipotesi di associazione tra l’evento del 1703 e la faglia del m. marine. attraverso l’applicazione di relazioni empiriche che legano la magnitudo momento con la lunghezza della faglia e considerando la struttura del m. marine come parte del sistema di faglie di l’aquila (circa 25 km di lunghezza), è possibile ipotizzare che l'attivazione della sorgente, la cui espressione superficiale si manifesta con il sistema menzionato, sia in grado di produrre terremoti con mw prossima a 6.7. abstract paleoseismological analyses along the mt. marine fault (high aterno valley): preliminary results.the south-western side of mt. marine is characterized by a nw-se trending normal fault, which has been responsible for the formation of the alto aterno intermontane basin. this area was affected by the earthquake of 2 february 1703 (me=6.7), which represents the last seismic event of a sequence characterized by two other main earthquakes occurred during january 1703. during investigations aimed at realizing a “prototipe geological map”, some fault scarps (wnw-ese trending), have been recognized at the base of mt. marine; these scarps are related to the recent fault activity. the identification of the fault scarps suggested to perform paleoseismological analyses in the area. a trench was dug across the 10-m-high southernmost scarp. on the basis of the sedimentological and paleoenvironmental characteristics, the stratigraphic sequence recognized within the trench was divided in 4 different complexes, separated by 3 fault zones. the different ages of the defined complexes has been confirmed by the results of the radiocarbon analysis. paleoseismological analyses indicate the occurrence of a minimum of five displacement events within the last 15,000 years; the most recent of these events is probably related to the 2 february 1703 earthquake, as indicated by the displacement of historical colluviums and by the historical information on the geological coseismic effects in the investigated area. displacements observed along the secondary faults of the main fault zones vary between 0.10 and 0.60 m. considering the magnitude (me=6.7) associated with the 2 february 1703 earthquake and on the basis of the empirical relationships between earthquake magnitude and surficial displacement, a maximum displacement per event of about 1 m can be expected. paleoseismological studies provided, therefore, further information about the association between the 1703 seismic event and the mt. marine fault. also the magnitude related to this event (me=6.7) is comparable with the mw (6.7) which can be derived from the equations linking this kind of magnitude with the length of the surficial fault expression of the entire l’aquila fault system (about 25 km). parole chiave: scarpata di faglia, italia centrale, fagliazione superficiale, paleoterremoto, paleosismologia keywords: fault scarp, central italy, surface faulting, paleoearthquake, paleoseismology. il quaternario italian journal of quaternary sciences 1155(2), 2002, 259-270 11.. iinnttrroodduuzziioonnee nell'ambito del progetto per la realizzazione di una "cartografia geologica prototipale" (accordo di programma tra servizi tecnici nazionali, servizio geologico nazionale e consiglio nazionale delle ricerche) sono stati eseguiti rilievi di campagna finalizzati alla definizione dell’assetto geologico evolutivo della zona dell’alta valle dell’aterno. nel corso delle indagini sono state riconosciute alcune scarpate di faglia nella fascia pedemontana del m. marine, con direzione wnw-ese. la formazione di tali scarpate è da ricondurre all'attività recente della faglia che borda, per l'intera lunghezza, il versante sudoccidentale del m. marine. questa ha un andamento medio da nw-se a wnw-ese ed è ritenuta responsabile della formazione del bacino intermontano dell’alto aterno (bosi, 1975; blumetti, 1995; blumetti et al.., 1996; basili et al., 1997; 1999). in questo lavoro vengono descritti i primi risultati ottenuti dallo studio di una trincea paleosismologica scavata attraverso una delle scarpate di faglia menzionate associate alla struttura del m. marine. mediante l’osservazione delle foto aeree, la mappatura e il riconoscimento sul terreno della scarpata, sono stati identifica260 m. moro et al. ti siti potenziali per lo scavo di trincee esplorative. la realizzazione di una trincea paleosismologica ha permesso di determinare la natura tettonica della scarpata; quest’ultima è risultata essere l’espressione superficiale di una faglia diretta parallela al versante di faglia e responsabile della dislocazione di depositi alluvionali, di versante e di coltri colluviali recenti (olocene) (fig. 1). l'analisi condotta ha fornito informazioni sulla cinematica della struttura ed ha permesso il riconoscimento di eventi di dislocazione cosismica recenti. a questo proposito va ricordato che l’area è stata interessata da un terremoto distruttivo il 2 febbraio 1703 (me=6.7, gruppo di lavoro cpti, 1999). inoltre blumetti (1995), in base all’osservazione di dislocazioni di depositi colluviali tardo pleistocenici e delle descrizioni storiche degli effetti indotti sul terreno dal terremoto del 1703, ha ipotizzato l’attivazione della faglia del m. marine proprio in occasione di questo terremoto. dopo l'inquadramento geologico dell'area ed alcune indicazioni sulla sismicità, un ampio capitolo del presente lavoro è dedicato ai vari aspetti connessi all'analisi paleosismologica: dall'individuazione e caratterizzazione della scarpata di faglia, alla realizzazione della trincea, descrizione delle varie unità dislocate individuate, interpretazione in termini stratigrafici e inquadramento cronologico dei singoli eventi di fagliazione individuati. alcune implicazioni dei risultati ottenuti saranno evidenziati nelle conclusioni. figura 1. localizzazione ed inquadramento geologico del sito. 1, sedimenti sabbioso-limosi e coltri colluviali; 2, brecce calcaree di versante; 3, successione carbonatica; 4, scarpate di faglia secondarie; 5, faglia diretta (a) e suo probabile prolungamento (b); i trattini indicano la parte ribassata; 6, sito della trincea. geological framework and location of the site. 1, sandy-silty sediments and colluvial deposits; 2, slope-derived calcareous breccias; 3, carbonate succession; 4, secondary fault scarps; 5, normal fault (a) and its probable extension (b); hatching on downthrown side; 6, trench site. 22.. iinnqquuaaddrraammeennttoo ggeeoollooggiiccoo ddeellll’’aarreeaa l'alta valle del f. aterno è una depressione allungata in direzione nw-se all’interno della dorsale appenninica, nel settore più settentrionale dei rilievi abruzzesi. nel tratto tra barete e arischia la valle si immette in un’ampia depressione in gran parte di origine tettonica, bordata dalla faglia del m. marine, che tende a congiungersi verso sud con la conca aquilana. i rilievi che bordano la valle sono costituiti da rocce calcareo-dolomitiche appartenenti alla successione meso-cenozoica laziale-abruzzese, mentre in prossimità del fondovalle affiorano depositi fluviali e lacustri plio-quaternari terrazzati e depositi clastici di versante; solo nel tratto a nord di s. giovanni, il fondovalle dell’aterno è inciso anche nei depositi silicoclastici miocenici. per quanto riguarda gli studi di tettonica plio-quaternaria, i dati geologici disponibili per quest’area sono riportati in bosi (1975), blumetti (1995), bagnaia et al. (1996), blumetti et. al. (1996), basili et al. (1997), basili et al. (1999), galadini (1999) e galadini & galli (2000). più recentemente, bosi et al. (2000) e moro et al. (2001) hanno realizzato una carta geologica in cui sono rappresentati gli eventi sedimentari ed erosivi occorsi durante il plio-quaternario. dall’analisi delle informazioni contenute nella carta emerge un quadro di evoluzione geologica caratterizzato dalla presenza di almeno nove episodi sedimentari e numerosi eventi erosivi. dal punto di vista dell’assetto strutturale, va evidenziato il fatto che la faglia del m. marine fa parte di un sistema composto da quattro segmenti principali (fig. 1) disposti en-echelon con step-over destro (galadini, 1999; galadini & galli, 2000; galadini & messina, 2001) che si sviluppa tra il bacino di capitignano (a nord dell'area studiata) e la città di l'aquila. nell'ambito dell'intero sistema di faglia, tuttavia, le evidenze più marcate di attività tardo-quaternaria riguardano proprio il segmento di m. marine e quello subito a sud, noto come faglia del m. pettino. il primo ha andamento da nw-se a wnwese e si sviluppa tra gli abitati di marana e arischia, mentre il secondo, con andamento da nw-se ad e-w, termina verso nw tra gli abitati di s. vittorino e s. marco e verso sud a ridosso di l'aquila (fig. 1). entrambe le faglie, ritenute attive nel pleistocene superiore-olocene (bosi, 1975; blumetti, 1995; blumetti et al., 1996; basili et al., 1997; basili et al., 1999; galadini & galli, 2000), sono caratterizzate da evidenti scarpate di faglia in roccia e, spesso, da ampie zone cataclastiche laddove tagliano la serie meso-cenozoica. 33.. ssiissmmiicciittàà ddeellll’’aallttoo aatteerrnnoo le informazioni riguardanti la sismicità storica evidenziano che l'area è stata interessata nel 1703 da una delle più distruttive sequenze sismiche che hanno interessato l’italia peninsulare. la sequenza è caratterizzata da tre eventi principali, di cui l’ultimo (2 febbraio), con epicentro nella zona di l’aquila, è risultato di intensità pari a x mcs (gruppo di lavoro cpti, 1999). la cronologia degli eventi principali (14 gennaio, 16 gennaio, 2 febbraio) e l'ubicazione delle aree epicentrali evidenziano l'attivazione progressiva di sorgenti sismogenetiche in direzione appenninica, da nord verso sud. 261analisi paleosismologiche ... le numerose scosse causarono rilevanti effetti sull'ambiente, descritti da grimaldi (1703), uria de llanos (1703) e parozzani (1887): voragini e spaccature nel terreno, fuoriuscita di materiale infiammato e di gas sulfurei, dissesti di vario tipo e modifiche nell'andamento del corso dei fiumi, formazione di laghi di piccole dimensioni. in particolare, nei dintorni di arischia si formarono due aperture nel terreno dalle quali fuoriuscirono pietre e grandi quantità d'acqua, con formazione di un piccolo bacino idrico. nei monti vicini alla località colle vi fu caduta di massi e si aprirono spaccature nel terreno: in una di queste, lunga circa 3 km (2 miglia), precipitarono anche alcune pecore. a pizzoli è ricordata l'apertura di due fenditure, da una delle quali uscì una grande quantità di materiale roccioso e dell’acqua bianca che aveva formato un laghetto. per quanto riguarda altri terremoti distruttivi, l'informazione storica evidenzia che l'area aquilana è stata interessata da una delle scosse della disastrosa sequenza del 1349 (i pari a ix-x mcs a l'aquila, monachesi & stucchi, 1997). prima di questo evento, tuttavia, l'area aveva già subito il terremoto del 1315, i cui effetti sono, tuttavia, poco noti. successivamente, l'aquila e l'alto aterno sono stati interessati dal terremoto del 1461 e da quello del 1762 (i x e ix rispettivamente a l'aquila) con effetti non paragonabili a quelli dei terremoti del 1349 e del 1703. gli unici dati sismologici strumentali relativi alla sismicità minore dell'alta valle dell'aterno sono stati pubblicati da bagnaia et al. (1996). in tale lavoro sono stati analizzati i dati raccolti, a partire dal 1992, da una rete locale gestita dal servizio sismico nazionale in collaborazione con il dipartimento di fisica dell’università di l’aquila. l’attività sismica risulta concentrata in due sequenze, una nell’agosto del 1992 (mmax = 3.9) e l’altra nel giugno 1994 (mmax = 3.7). lo sciame della prima sequenza è localizzato tra il m. san franco ed il m. stabiata con una concentrazione degli ipocentri all’interno di una stretta fascia tra 8 e 12 km. le soluzioni focali indicano meccanismi dip-slip con piani di faglia a direzione prevalente nw-se ed assi t orientati in direzione antiappenninica, compatibili con il regime tettonico distensivo che caratterizza questo settore dell’appennino centrale. nel 1994 l'area è stata interessata da un secondo sciame con un evento principale, il 2 giugno, di magnitudo pari a 3.7. la distribuzione spaziale degli eventi è concentrata in una fascia adiacente le località di barete, pizzoli e m. marine. secondo bagnaia et al. (1996) gli ipocentri proiettati in direzione e-w interessano volumi focali raggruppati nei primi 15 km di crosta, a profondità tipiche dei terremoti appenninici. 44.. iinnddaaggiinnii ppaalleeoossiissmmoollooggiicchhee 4.1 geomorfologia del sito la scelta del sito della trincea è il frutto di analisi morfologiche eseguite nell’ambito degli studi per la realizzazione di una carta geologica prototipale (bosi et al., 2000; moro et al., 2001). oltre alla scarpata principale, ubicata al piede del versante carbonatico, sono state evidenziate tre ulteriori scarpate di altezza variabile tra 10 e 20 metri (fig. 1). queste scarpate sono state ritenute di origine tettonica in base ai seguenti elementi: 262 non sono riferibili alla successione terrazzata dell’alta valle dell’aterno; non sono riferibili ad attività antropica (i muri a secco osservabili lungo alcuni tratti delle scarpate sono di limitata altezza ed hanno il solo scopo di impedire fenomeni franosi di piccola entità in una zona densamente abitata). l’analisi delle foto aeree ed i rilievi sul terreno lungo le scarpate che interessano i depositi di versante hanno mostrato che in generale questi tre elementi morfologici interessano principalmente aree caratterizzate da erosione durante l’olocene. l’esiguità di affioramenti di depositi olocenici ha consentito di identificare in questa fase due soli siti per lo scavo di trincee esplorative. i siti identificati si localizzano sulla scarpata più meridionale rispetto alle tre riconosciute (fig. 1). in questa area la faglia assume una direzione wnw-ese. nella figura 1 sono riportate le unità affioranti in prossimità del sito paleosismologico. oltre alle formazioni calcareo-dolomitiche presenti sul versante di m. marine, sono state evidenziate due unità riferibili al pleistocene superiore olocene: l’unità 1 è costituita da più livelli sabbioso-limosi e da coltri detritiche provenienti dai soprastanti versanti; comprende inoltre i depositi di due conoidi detritiche (pleistocene sup. olocene). l’unità 2 è costituita da brecce calcaree di versante ben stratificate a cui si intercalano alcuni livelli centimetrici sabbioso-limosi ricchi di materiale organico. le datazioni con il metodo del radiocarbonio eseguite su due di questi livelli hanno fornito età rispettivamente di 31.710±760 e 23.330±300 yr b.p. (galadini & galli, 2000). questa unità è dislocata dal sistema di faglie presenti al piede del versante del m. marine e nel settore ribassato della struttura i depositi non affiorano in quanto ricoperti da unità più recenti. 4.2 aspetti tecnici dell'analisi paleosismologica la trincea è stata scavata trasversalmente alla scarpata di faglia (fig. 2) con direzione n25°e, è lunga circa 28 metri, raggiunge una profondità e larghezza media di 2 metri ed interessa depositi alluvionali, colluviali e di versante. allo scopo di cartografare in dettaglio le pareti della trincea, è stato applicato un reticolo a maglie quadrate di un metro di lato e nelle zone in cui necessitava un maggior dettaglio stratigrafico la larghezza delle maglie è stata portata a 0.5 m di lato. i dati desumibili dalle pareti della trincea sono stati trasferiti su carta millimetrata in scala 1:20. sono state altresì effettuate riprese fotografiche di dettaglio delle pareti con fotocamera digitale, a distanza fissa (circa 1 m) per ogni fotogramma. ciò ha permesso di realizzare un fotomosaico delle pareti, grazie alla retrodeformazione delle immagini vincolata dalla geometria del reticolo. l’età dei paleoeventi è stata vincolata sulla base di datazioni radiometriche 14c effettuate su campioni prelevati dalle unità stratigrafiche. le datazioni sono state eseguite presso il laboratorio beta analytic inc. (miami-florida). le età convenzionali sono state calibrate da beta analytic utilizzando il database intcal98 di cui in stuiver et al. (1998). la conoscenza dei processi deposizionali ed erosivi, relativi all’evoluzione geologica del pleistocene superiore-olocene in questo settore appenninico, ha permesso di definire una cronologia relativa per i comm. moro et al. figura 2. veduta panoramica del sito paleosismologico. le linee a tratteggio indicano la parte superiore ed inferiore della scarpata di faglia. le frecce mostrano l’andamento in superficie della scarpata. view of the paleoseismological site. dashed lines indicate the top and the bottom of the fault scarp. arrows shows the superficial pattern of the scarp. 263 plessi sedimentari riconosciuti. come mostrato nel seguito, ciò ha consentito di superare alcune difficoltà legate alla definizione di vincoli cronologici mediante datazioni quantitative. 4.3 contesto stratigrafico e misure radiocarboniche nell’ambito della successione indagata sono state riconosciute 10 unità distinte sulla base dei principali caratteri lito-pedostratigrafici e del loro significato sedimentologico-paleoambientale (tab. 1). i rapporti stratigrafico-tettonici esistenti fra le unità attraversate dalla trincea permettono, inoltre, di suddividere l’intera successione in quattro principali complessi (fig. 3). i principali elementi di discontinuità stratigrafica che consentono una simile suddivisione sono rappresentati dalle tre zone di deformazione a, b e c (fig. 3, 4, 5, 6 e 7). i quattro gruppi di unità, che attraverso tali elementi vengono a contatto fra loro, non mostrano infatti alcun tipo di affinità sedimentologico-stratigrafica; essi pertanto possono essere trattati come complessi discreti stratigraficamente e cronologicamente ben distinti gli uni dagli altri. tale suddivisione è corroborata dalla cronologia radiocarbonica disponibile riportata in tab. 2. 4.3.1 indizi cronologici forniti dal contesto stratigrafico-paleoambientale sebbene in ambito paleosismologico le misure cronometriche siano un requisito essenziale, esse in ogni caso costituiscono solo una parte del complesso di dati necessari per la definizione di una precisa cronologia della sequenza stratigrafica e degli eventi paleosismici riconosciuti. nel caso in esame, il riconoscimento di alcuni elementi di potenziale valenza tefrocronologica nonché l’analisi dell’evoluzione stratigrafico-paleoambientale della successione indagata permettono di migliorare e ridefinire il quadro cronologico fornito dalle misure radiocarboniche. per quanto concerne la parte più antica della successione (complesso 1 fig. 3 e 5), l’elemento più significativo ai fini cronologici è senza dubbio rappresentato dalla sequenza costituita dal tephra ridepositato (unità 8a e 8b) e dal paleosuolo che ne interessa il tetto (unità 7a) la cui frazione organica ha fornito un’età di 30.110±310 yr 14c b.p. la componente vulcanica del tephra rimaneggiato è costituita in larga misura (>90%) analisi paleosismologiche ... figura 3. riproduzione grafica e fotomosaico della parete ovest della trincea. sono indicate con i riquadri a tratteggio le tre zone principali di deformazione a,b,c. le unità stratigrafiche così come le zone principali di faglia vengono descritte nel testo. le faglie sono indicate in nero nello schema grafico ed a tratteggio bianco nel fotomosaico. sketch and photomosaic of the western trench wall. dashed squares indicate the three principal deformation zones a,b,c. stratigraphic units and the principal fault zones are described in the text. faults are indicated with black lines in the sketch and with white dashed lines in the photomosaic. 264 da ceneri molto sottili, dal tipico colore giallastro assunto dai vetri in seguito ad un processo di alterazione, mentre la frazione psammitica si compone di vetro grigio ben vescicolato associato a fenocristalli di mica, pirosseno e plagioclasio in abito discretamente conservato. il paleosuolo limoso, si presenta ben sviluppato (spessore 70-100 cm) con un orizzonte b bruno-nerastro (7,5yr3/2) che, tramite un orizzonte nodulare discontinuo, sfuma gradualmente in c. entrambi gli orizzonti b e c sono ben distinti e rappresentati, mentre l’orizzonte a, troncato al tetto da una superficie di erosione, affiora solo in lembi residui. a completamento di quanto ossservato, va ricordato che a meno di un chilometro ad est della trincea, nell’abitato di frattole, blumetti (1995) ha descritto una sequenza di depositi quaternari recenti interessata da un fitto e complesso sistema di faglie dirette. questa successione presenta nella parte alta un paleosuolo, sviluppato su tephra giallastro, che ha fornito un’età di 29.690±1110 yr 14c b.p. del tutto simile a quella del paleosuolo rinvenuto nella trincea paleosismologica (in seguito pt). un esame delle caratteristiche mineralogico-sedimentologiche del livello pedogenizzato e del parent material del paleosuolo di frattole (in seguito pf) hanno inoltre evidenziato forti analogie lito-pedostratigrafiche fra i due paleosuoli che, in aggiunta ai dati cronometrici, ne confermano la correlazione. sui rilievi carbonatici dell’appennino centrale è stato identificato, in diversi contesti deposizionali subaerei, un pedomarker tardopleistocenico sviluppatosi su un tephra rimaneggiato correlato all’ignimbrite campana (frezzotti & narcisi, 1996). il paleosuolo è classificato come un andosuolo sviluppatosi sotto condizioni climatiche temperato umide, evolutosi a luvisol in seguito ad m. moro et al. tabella 1. descrizione litostratigrafica, interpretazione sedimentologica e cronologia della trincea marruci 1. lithostratigraphic description, sedimentological interpretation and chronology of the marruci 1 trench. unità liv. descrizione interpretazione misure 14c età (ky bp) 10 a-c ghiaie grossolane caotiche con elementi eterometrici e poco elaborati in scarsa sedimenti alluvionali matrice sabbiosa. verso l’alto le ghiaie passano a livelli decimetrici di sabbie fini. 9 a-e ghiaie stratificate (clast-supported) con elementi calcarei subarrotondati passanti sedimenti alluvionali >39,3 verso l’alto a sabbie fini interessate da patine manganesifere. 8 a-b sabbie fini e silt giallastro a prevalente componente vulcanica con intercalazioni tephra rimaneggiato 39,3÷37,81 di ghiaie (8a) in strati decimetrici lenticolari. dell’ignimbrite campana 7 a limo bruno-giallastro a prevalente componente vulcanica. orizzonte b/c di alterazione 37,8÷341 pedogenetica b limo bruno-nerastro (7,5 yr3/2) con abbondante materiale organico, incrostazioni orizzonte b di alterazione 30.310±310 e noduli calcarei . pedogenetica erosione 6 limo sabbioso bruno-nerastro con rari clasti calcarei. colluvio del sottostante <34 paleosuolo (7) 5 a-f alternanze di ghiaie ben stratificate ed embriciatie e sabbie in livelli decimetrici e sedimenti alluvionali 33.580±270 geometria lenticolare e cuneiforme. 4 a-f ghiaie calcaree eterometriche e massive ad elementi subangolosi corrosi, a luoghi depositi di versante 24÷18 stratificate in livelli decimetrici con rari intervalli sabbiosi. 3 a-g ghiaie grossolane mal stratificate con abbondante matrice limosa ed intercalazioni sedimenti 21.090±280 <24 decimetriche di limo sabbioso. alluvio-colluviali >16 2 f-e limi sabbiosi bruno-giallastri amalgamati, mal stratificati con elementi calcarei sedimenti colluviali 12.930±260 <16 eterometrici. 2 a-c limi sabbiosi amalgamati, mal stratificati con rari elementi calcarei eterometrici e sedimenti colluviali 3880±70 <22 frammenti di laterizi di età storica (2c-2a). 1 limo sabbioso bruno suolo attuale 1giaccio et al., 2002; giaccio & isaia submitted; 2età desunta dal contenuto archeologico. tabella 2. età 14c dei campioni prelevati in trincea ottenute sulla base di datazioni radiometriche calibrate e dendrocorrette. la localizzazione dei campioni è riportata in figg. 4, 5, 6, e 7 (esclusi i campioni piz4 e piz7, non rappresentati nel log della trincea). l’intervallo 2σ è dato secondo il programma di calibratura del radiocarbonio di stuiver et al. (1998). measured and dendrochronologically calibrated 14c age of samples collected in the trench. sample location and age are shown in figures 4, 5, 6 and 7 (except for sample piz4 and piz7, which is out of the log of trench). the 2σ interval is given according to the radiocarbon calibration program of stuiver et al. (1998). camp. comp. unità liv. materiale datato cod. lab. tecnica età 14c bp 2σ età cal. bp piz4 1 7 a paleosuolo beta-167950 radiometrica 30.110 310 ~35.0902; ~34.1003 piz3 1 5 e carbone beta-167949 ams 33.580 270 ~38.9002; ~37.4003 piz7 3 3 e silt colluviale beta-167951 radiometrica 21.090 280 ~24.8002; ~24.0003 piz10 4 2 e silt colluviale beta-167952 radiometrica 12.930 260 16.160-14.3401 piz14 4 2 y silt colluviale beta-167953 radiometrica 3890 60 4500-4480/4440-41501 piz12 4 2 a silt colluviale beta-169188 radiometrica 3880 70 4520-4140/4120-41001 1stuiver et al., 1998; 2 bard, 1998; 3voelker et al., 2000 (2 -3calibrazione stimata). 265analisi paleosismologiche ... un successivo peggioramento climatico in senso freddoarido (frezzotti & narcisi, 1996). con l’eccezione di una singola datazione a 38.770±2100 14c yr b.p., numerose misure radiocarboniche indicherebbero che questo pedomarker appenninico (in seguito pma) si sia sviluppato nell’intervallo cronologico di 33.000-29.000 yr 14c b.p. (frezzotti & narcisi, 1996 con riferimenti). le età di 29.690±1110 e di 30.110±310 yr 14c b.p., rispettivamente del pf e del pt, si sovrappongono ampiamente alle misure radiocarboniche attualmente disponibili per il pma suggerendo pertanto una loro correlazione. le più recenti datazioni dei depositi prossimali terrestri dell’ignimbrite campana (in seguito ic), hanno fornito un’età di 39.280±110 yr b.p., ottenuta da 18 misure 40ar/39ar (de vivo et al., 2001), mentre la risedimentazione del tephra (unità 8) e la sua successiva pedogenesi (unità 7) sono state correlate rispettivamente all’heinrich event 4 (ca. 39.300÷37.800 cal yr b.p.) e agli interstadi 8-7 (ca. 37.500÷34.000 cal yr b.p.) della stratigrafia isotopica groenlandese (giaccio et al., 2002; giaccio & isaia, 2002). tramite le zone di deformazione b e c, rappresentate rispettivamente da un sistema di faglie normali e da una faglia diretta antitetica del sistema del m. marine, il complesso 1 è messo a contatto con i più recenti depositi dei complessi 2 e 3 (fig. 3, 5 e 6). i depositi del complesso 2 (unità 4a-f) evidenziano un netto cambiamento di facies rispetto alla sequenza del complesso 1. si tratta di ghiaie calcaree massive mal stratificate e mal classate ad elementi subangolari con scarsa matrice sabbiosa totalmente priva di componente organica e/o di sedimenti di suolo così frequenti nei livelli sottostanti. essi, per la posizione stratigrafica che occupano e le caratteristiche di facies che li contraddistinguono, possono essere dubitativamente correlati alle fasi di gelifrazione e sedimentazione detritica di versante dell’ultimo massimo glaciale ampiamente documentate in appennino centrale fra 21.000 e 18.000 14c yr b.p. (giraudi & frezzotti, 1997). il complesso 3 (unità 3a-g) è invece costituito da alternanze di livelli ghiaiosi e sabbioso-limosi presumibilmente riferibili a processi di sedimentazione alluvionale e colluviale. la frazione organica di un campione di sabbie-limose colluviali (livello 3e) di questo complesso ha fornito l’età di 21.090±280 14c yr b.p. considerando la natura colluviale del materiale datato, per questi sedimenti tale data va intesa come termine post quem per la sedimentazione, mentre si può assumere come età minima la data di 12.930±280 14c yr b.p. della base del complesso 4 riferibile all’intervallo tardiglaciale-olocene recente. l’attribuzione a tale ambito cronologico è suggerita sia dai dati cronometrici (tab. 1) sia dall’evidenza stratigrafica di numerosi frammenti laterizi fluitati di età storica (rolfo, com. pers.) distribuiti nella parte alta della sequenza (livelli 2a-c). la serie tardiglaciale-olocenica si compone di sedimenti colluviali amalgamati e malstratificati, tali da rendere piuttosto arbitraria una precisa individuazione dei limiti di base e tetto delle quattro unità riconosciute che rappresentano, in ogni caso, altrettanti distinti episodi colluviali. nell’ambito di territori caratterizzati da una costante occupazione umana storico-protostorica associata ad una massiccia attività agricolo-pastorale, quale è certamente il caso in esame, è estremamente critica la distinzione degli effetti geologico-ambientali dovuti all’impatto antropico da quelli ascrivibili alle oscillazioni climatiche oloceniche. studi stratigrafici ad alta risoluzione hanno in ogni caso evidenziato un comportamento ciclico del clima olocenico con un periodo di circa 1500±500 yr (bond et al., 1997; mayewski et al., 1997; bond et al., 2001). nell’ambito di questa ciclicità, nel periodo storico (ultimi 2500) si sarebbero verificati due episodi principali di raffreddamento centrati, rispettivamente, intorno a 1400 e 350 yr b.p. che corrispondono a due fasi di dissesto ambientale ben documentate nel territorio italiano (es. cremaschi & gasperi, 1989; ortolani & pagliuca, figura 4. riproduzione grafica della zona di deformazione a della parete ovest della trincea. le unità stratigrafiche e le deformazioni vengono descritte all’interno del testo. le frecce rappresentano gli orizzonti evento relativi agli eventi di dislocazione riconosciuti. sketch of the deformation zone a of the western trench wall. stratigraphic units and deformation zones are described in the text. arrows represent the event horizons related to the recognized displacement events. 266 m. moro et al. figura 5. riproduzione grafica della zona di deformazione b della parete ovest della trincea. le unità stratigrafiche e le deformazioni vengono descritte all’interno del testo. le frecce rappresentano gli orizzonti evento relativi agli eventi di dislocazione riconosciuti. sketch of the deformation zone b of the western trench wall. stratigraphic units and deformation zones are described in the text. arrows represent the event horizons related to the recognized displacement events. 1994; veggiani, 1995; antonioli et al., 2000; giraudi, in stampa ). a questi periodi, noti nella letteratura della climatologia storica come la “fase dei dissesti alto medievali” e la “piccola età glaciale”, sono associati episodi di intensa erosione di suoli e accumulo di sedimenti colluviali . alla luce di quanto precede, e considerando la criticità interpretativa delle misure cronometriche ottenute dai sedimenti colluviali di questo complesso, è possibile correlare dubitativamente la parte alta delle unità oloceniche, contenenti laterizi storici, ad una fra le due ultime fasi di instabilità ambientale dell’alto medioevo e della piccola età glaciale. 4.4 deformazioni osservate ed eventi di dislocazione cosismica riconosciuti i rapporti tra le unità stratigrafiche ed i vari piani di taglio esposti in entrambe le pareti dello scavo hanno portato al riconoscimento delle tre zone di deformazione principali indicate in figura 3 e citate nel paragrafo precedente. le zone sono composte da sistemi più o meno complessi di faglie prevalentemente dirette, ad alto angolo, con orientamento wnw-ese, che ribassano il settore sudoccidentale (tranne la faglia f6 che ribassa il settore settentrionale). le relazioni tra unità stratigrafiche e piani di taglio hanno permesso di riconoscere l'occorrenza di almeno cinque eventi di fagliazione superficiale. la zona di deformazione a (fig. 3, 4 e 7) risulta ampia circa 2 m; è composta da una serie di faglie dirette ad alto angolo (f2) con locale movimento inverso (f1) e mette a contatto due differenti sequenze stratigrafiche (complesso 3 e 4). la sequenza delle unità 2 (da 2c a 2f) risulta costituita da corpi colluviali massivi recenti (presenza al loro interno di frammenti di ceramica storica) mentre la sequenza 3 è rappresentata da depositi alluvio-colluviali mal stratificati che potrebbero costituire il prodotto della rielaborazione delle unità alluvionali più antiche 5-10 (complesso 1). la faglia è sigillata dall’unità 2a che poggia indisturbata sulle sequenze sottostanti. la zona di deformazione b (fig. 3 e 5) presenta un'ampiezza di circa 5 m e risulta costituita da una serie di faglie normali ad alto angolo localmente con movimento inverso. la faglia principale (f5) mette a contatto la sequenza stratigrafica 3 (complesso 3) con la 5-10 (complesso 1), costituita prevalentemente da depositi fluviali a diverso grado di energia deposizionale, con stratificazione suborizzontale, riferibili ad un livello di base antico non corrispondente con l'attuale. tale faglia disloca l’intera sequenza stratigrafica fino alla base del suolo attuale. la struttura f4 che interessa la sequenza 3 presenta una diminuzione dell’entità del rigetto verticale procedendo verso la porzione superiore della sequenza, ad indicare una riattivazione della struttura. in particolare la base dell’unità 3e ed il tetto dell’unità 3c risultano dislocati rispettivamente di circa 0,50 m e 0,30 m. le faglie che interessano la sequenza 5-10 presentano una entità del rigetto costante e tagliano l’intera sequenza fino alla base del suolo attuale mostrando un rigetto massimo osservabile di circa 0,60 m. la zona di deformazione c (fig. 3 e 6) risulta ampia circa 3 m ed è composta da strutture antitetiche e da strutture a movimento inverso. la faglia antitetica f6 mette a contatto i depositi detritici di versante della sequenza 4 (complesso 2) con la sequenza 5-10 (complesso 1) ed è sigillata dal suolo attuale. nella parete est uno degli ultimi livelli dislocati presenta al suo interno un frammento di ceramica storica. sono presenti altre strutture a componente inversa che mostrano rigetti di 0,1-0,15 m. in tutta la trincea si osservano inoltre strutture e fratture secondarie con rigetti minimi o nulli. l’analisi delle sequenze sedimentarie unitamente allo studio delle strutture deformative ha permesso di identificare le evidenze geologiche di almeno cinque eventi di dislocazione cosismica. l’evento più recente (e1) è desumibile dalla dislocazione, nella zona a, dell’intera sequenza stratigrafica fino alla base dell’unità 2a; la dislocazione riguarda unità recenti che contengono frammenti di ceramica storica. nelle zone b e c tutte le unità sono dislocate, ad 267analisi paleosismologiche ... figura 6. riproduzione grafica della zona di deformazione c della parete ovest della trincea. le unità stratigrafiche e le deformazioni vengono descritte all’interno del testo. le frecce rappresentano gli orizzonti evento relativi agli eventi di dislocazione riconosciuti. sketch of the deformation zone c of the western trench wall. stratigraphic units and deformation zones are described in the text. arrows represent the event horizons related to the recognized displacement events. eccezione del suolo attuale. l'evento e1 ha causato la formazione di una scarpata la cui degradazione ha alimentato la deposizione del cuneo colluviale 2b e successivamente 2a, osservabile nella zona a delle pareti. anche nella zona c, così come nella zona a, la dislocazione interessa un livello contenente manufatti storici. tale evento ha prodotto un progressivo ribassamento verso s delle sequenze stratigrafiche. l’entità minima del rigetto calcolata per questo evento è risultata di 0,3 m, considerando la dislocazione dell’unità 2d (fig. 7). nonostante l'analisi col metodo del radiocarbonio dei depositi fagliati (unità 2y) e di quelli sigillanti (2a) fornisca età piuttosto antiche (vedi tabella 2), la presenza di ceramica storica garantisce che tali livelli siano il frutto di colluviamento da riferire ad una fra le due più recenti fasi di instabilità climatica; la deposizione sarebbe pertanto da riferire o all’alto medioevo o alla piccola età glaciale, come detto in precedenza. questa osservazione, unita alle evidenze storiche sugli effetti geologici del terremoto del 2 febbraio 1703, alla localizzazione dell’epicentro e all’intensità di questo evento sismico, permette di associare ad esso l'evento di dislocazione e1. un ulteriore evento (e2) è riconoscibile nella zona a della parete est (fig. 7), a causa della presenza di un probabile cuneo colluviale (unità 2d), che dovrebbe rappresentare il prodotto dello smantellamento di una scarpata di faglia prodottasi durante e2. il cuneo colluviale (unità 2d) verrà successivamente fagliato dall’evento e1, più recente, descritto in precedenza. nella parete est, in corrispondenza della faglia f3 268 m. moro et al. figura 7. riproduzione grafica della zona di deformazione a della parete est della trincea. le unità stratigrafiche e le deformazioni vengono descritte all’interno del testo. le frecce rappresentano gli orizzonti evento relativi agli eventi di dislocazione riconosciuti. sketch of the deformation zone a of the eastern trench wall. stratigraphic units and deformation zones are described into the text. arrows represent the event horizons related to the recognized displacement events. (fig. 7), è possibile riconoscere altri due eventi: il più recente (e3) disloca la parte basale dell’unità 3a (f4 di fig. 5 e f3 di fig. 7), producendo un rigetto di circa 0,30 m; l’evento più antico (e4) interessa l’intera successione 3 fino al tetto dell’unità 3b, con l’unità 3a che ne sigilla il piano di faglia. in base alle considerazioni riportate nel paragrafo 4.3.1, si ipotizza che la porzione superiore del complesso 3 sia riferibile all’intervallo di tempo 15.00012.000 b.p.; l’età di questi due ultimi eventi è quindi attribuibile al periodo tardiglaciale. l’evento più antico (e5) è riconoscibile nella zona b (parete ovest) sulla struttura f4 (fig. 5), a causa dell’aumento del rigetto tra le unità 3c e 3e, che passa da circa 0,30 m a 0,50 m. l’età del campione piz 7 relativo all’unità 3e è risultata di 21.090±280 yr bp; considerando la natura colluviale di tali depositi, l’età di sedimentazione di tale livello potrebbe essere ringiovanita come detto nel capitolo 4.3.1, fino a circa 12.930±280 yr b.p. l’evento riconosciuto sarebbe quindi databile al periodo tardiglaciale (15.000-12.000 b.p.). la mancanza di correlazioni stratigrafiche fra i vari complessi sedimentari non consente di individuare il rigetto complessivo degli eventi individuati. 55.. ccoonncclluussiioonnii l'identificazione di scarpate di faglia formatesi con l'attività recente (pleistocene superiore-olocene) della faglia del m. marine ha suggerito di approfondire le caratteristiche di tale attività mediante analisi paleosismologica. la scarpata attraverso la quale è stata realizzata la trincea paleosismologica si è formata a causa dei movimenti ripetuti di alcuni piani di faglia che costituiscono parte dell'espressione superficiale della struttura del m. marine. l'analisi paleosismologica ha evidenziato l'occorrenza di eventi di dislocazione nel pleistocene superiore e nell'olocene. in particolare la trincea ha esposto evidenze relative a cinque eventi nell'ambito degli ultimi 15.000 anni. il più recente di tali eventi è da riferire con molta probabilità al terremoto del 2 febbraio 1703, come evidenziato dalla fagliazione di colluvi storici e dalle informazioni storiche sugli effetti geologici del terremoto. le dislocazioni osservate lungo le singole faglie presentano rigetti variabili tra 0,10 e 0,60 m; tali valori, alla luce delle osservazioni sulle deformazioni prodotte dall’ultimo evento (e1), potrebbero rappresentare un minimo se si ipotizza la riattivazione contemporanea dei vari piani di faglia durante un singolo evento sismico. nel complesso, l'analisi paleosismologica ha fornito vincoli geologici più affidabili riguardo l’ipotesi di associazione tra l’evento del 1703 e la faglia del m. marine, sebbene i risultati esposti abbiano carattere preliminare e si attenda la realizzazione di ulteriori scavi nell'area indagata. attraverso l’applicazione di relazioni empiriche che legano la magnitudo momento con la lunghezza della faglia (wells & coppersmith, 1994), e considerando la struttura del m. marine come parte del sistema di faglie di l’aquila (circa 25 km di lunghezza) (galadini & messina, 2001), è possibile ipotizzare che il sistema sia in grado di produrre terremoti con magnitudo prossima a 6.7. il riconoscimento di evidenze di deformazione legate con molta probabilità all’evento sismico del 2 febbraio 1703 (me = 6.7) permette di definire per la faglia del m. marine un tempo intercorso dall'ultimo evento di fagliazione di superficie piuttosto ridotto (dell'ordine dei 300 anni). considerando i dati disponibili sui tempi di ritorno delle faglie appenniniche (in genere superiori al millennio, si veda galadini & galli, 2000, per una sintesi sull'argomento), le valutazioni relative al m.marine definiscono una scarsa probabilità di attivazione in un futuro di interesse sociale. infine, l'individuazione di cinque eventi di dislocazione negli ultimi ca. 15.000 anni, sebbene la sequenza dislocativa sia probabilmente incompleta, è congruente con le indicazioni finora acquisite sui lunghi tempi di ritorno che caratterizzano le faglie appenniniche. rriinnggrraazziiaammeennttii il lavoro è stato parzialmente finanziato dal programma cnr agenzia 2000 “strutture attive nel sistema orogenico appenninico: caratterizzazione geomorfologica, geologico-strutturale, sismogenetica e geodetica”. a. cittadini ha partecipato alle attività di rilievo paleosismologiche. m. rolfo ha effettuato determinazioni archeologiche su frammenti ceramici. si ringrazia c. giraudi per le utili discussioni sulla stratigrafia delle unità riconosciute sulle pareti della trincea. si ringrazia infine f. cococcia per l’aiuto logistico fornito. bbiibblliiooggrraaffiiaa antonioli f., baroni c., camuffo d., carrara c., cremaschi m., frisia s., giraudi c., improta s., magri d., margottini c., orombelli g. & silenzi s. 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(2000) radiocarbon levels in the iceland sea from 25-53 kyr and their link to the magnetic field intensity. radiocarbon, 4422, 437-452. wells, d., & coppersmith k., (1994) new empirical relationships among magnitude, rupture length, rupture width, rupture area and surface displacement. bull. seismol. soc. am., 8844, 974– 1002. 270 m. moro et al. ms. ricevuto il 27 novembre 2002 testo definitivo ricevuto il 20 gennaio 2003 ms. received: november 27, 2002 final text received: january 20, 2003 amq29(2) 6 altamura 77-90.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 29 (1), 2016, 77 89 dietary behaviour of the pleistocene cretan dwarf deer: preliminary clues from mesowear analysis of candiacervus ex gr. candiacervus ropalophorus from bate cave sara altamura dipartimento di scienze della terra, università sapienza, rome, italy corresponding author: s. altamura <sara.altamura@gmail.com> abstract: during the middle and late pleistocene crete was inhabited by endemic dwarf deer. the smallest, candiacervus ex gr. candiacervus ropalophorus (sensu palombo et al., 2008) have been believed to have inhabited rocky environments characterised by typical mediterranean vegetation. this research aims to investigate dietary behaviour in the sample of the smallest deer found in the bate cave late middle early late pleistocene deposits (152,000±20% to 105,000±20% years). the molar teeth of candiacervus ex gr. c. ropalophorus from bate cave mainly show well-defined and high cusps, sometimes also perceptible in teeth in an advanced wear stage. therefore, it seems rational to suppose that deer had an eating behaviour approaching browsers. in order to substantiate this hypothesis, it was applied the mesowear method proposed by fortelius & solounias (2000) to infer the dietary behaviour of herbivores. the method was originally based on facet development on the occlusal surface of the second upper molar tooth, then extended to other molars, although results obtained show some inconsistencies. the number of m2 specimens of candiacervus ex gr. c. ropalophorus from bate cave is too low to be statistically valid. therefore, the analysis was extended to the last two lower and upper molars, divided in group according to their wear stage, with the double aim to check the consistence of results obtained by analysing upper and lower molars and verify to which extent wear may influence the cusp shape. the results obtained by extension of the method are encouraging, in fact all the teeth reveal the same trend suggesting a prevalent mixed-feeder habit for candiacervus ex gr. c. ropalophorus from bate cave although in some individuals a more marked browsing attitude is observed. a possible diet included leaves, shrubs and other tender and nutritious vegetation. key words: candiacervus ropalophorus, crete, mesowear, dietary behaviour, pleistocene. 1. introduction the study of feeding behaviour in herbivorous mammals (ungulates) is of particular interest to infer habitat preference and behaviour of fossil herbivores and provides some clues about the environment they inhabited. the food preference, indeed, reflects the vegetation cover and availability and partition of resources. according to their feeding behaviour, herbivores are generally classified into three main ecological groups: browser, grazer and mixed feeder. cervids are a highly heterogeneous group, most of species are ecologically flexible, some inhabit different environments, and some are opportunistic / mixed feeder, changing seasonality or occasionally their diet depending on resource availability and competition with other herbivores (see inter alios geist, 1999; palombo, 2005; yamada, 2012; de marinis & toso, 2015). the varied dietary habits of herbivores may be inferred by analysing the morphology of the tooth itself. in particular, the method of mesowear analysis, as originally proposed by fortelius & solounias (2000), provides information about the prevalent feeding behaviour of a species basing on the observation of occlusal facet of the second upper molar (m2). the development of this facet is related to the relative ratio of attrition (tooth-totooth contact) and abrasion (food-to-tooth contact) that occurs during mastication activities. according to fortelius & solounias (2000) the method provides stable trophic classification when at least 20 teeth are investigated. however, in the study of fossil species, sometimes the sample is not large enough to provide firm results. afterwards, the method has been extended to other teeth including the last two upper molars (twotooth model m2-m3) (franz-odendaal & kaiser; 2003; valli & palombo, 2008), all molars (m1÷m3, kaiser & croitor, 2004; m1÷m3 and m1÷m3 louys et al., 2011) or all the chewing teeth (four-tooth model p4÷m3; p4÷m3) (kaiser & solounias, 2003; kaiser, 2003; kaiser & fortelius, 2003). the method has been applied in several studies dealing with the dietary strategy in fossil and extant herbivores, such as equidae (kaiser & solounias, 2003; kaiser, 2003; kaiser & fortelius, 2003; mihlbachler et al., 2011; loffredo & desantis, 2014), cervidae (kaiser & croitor, 2004; palombo, 2005; valli & palombo 2008; yamada, 2012) and others (franz-odendaal & kaiser, 2003; kaiser & kahlke, 2005; clauss et al., 2007; rivals et al., 2011; louys et al., 2011; solounias et al., 2014). furthermore, in order to obtain data comparable with other possible variables (e.g. hypsodonty, %grass, habitat) (rivals & semprebon, 2006; kaiser et al., 2009; valli & palombo, 2008; loffredo & desantis, 2014) the fig. 1 skulls (a: female specimen 6; b: male specimen 3), jaws (c: sn1-sx; d: 8-dx) and mounted skeletons (e) of candiacervus ex gr. candiacervus ropalophorus from bate cave (paleontological museum of sapienza university, rome). 78 altamura s. mesowear qualitative variables (or and cusps shape) were combined to convert them into mesowear score: high relief and sharp cusps = ‘‘0’’, high relief and rounded cusp = ‘‘1’’, low relief and sharp cusp = ‘‘2’’, low relief and round cusp = ‘‘3’’, low relief and blunt cusp = ‘‘4’’. indeed, a score of 0 represents the most attritiondominated mesowear signals, while a score of 4 would represent the most abrasion-dominated signals. (rivals & semprebon, 2006; kaiser et al., 2009; mihlbachler et al., 2011). the research aims to infer the dietary behaviour of the cretan endemic deer, candiacervus ex gr. candiacervus ropalophorus (sensu palombo et al., 2008) (fig. 1), found in the bate cave (rethymnon) and dated between 150,000±20% and 105,000±20% years (aar method -reese et al., 1996). during the middle and late pleistocene, the crete island was inhabited by at least five endemic deer which originated from a radiative evolutionary process that led to a niche partition among deer species differing in size, habitat and feeding behaviour (de vos, 1996, 2000). the candiacervus ropalophorus group includes the smallest among the cretan endemic deer (candiacervus ropalophorus and candiacervus sp. ii in de vos, 1979, 1984, 1996), c. ex gr c. ropalophorus is believed to have inhabited rocky environments with a mediterranean vegetation and to have had a mixed diet mainly consisting of bushes, shrubs, leaves and grass, whose availability and quality were subject to seasonal variations (caloi & palombo, 1996; van der geer et al., 2006; van der geer et al., 2010; van der geer et al., 2014; mujica, 2014; palombo & zedda, 2015). to validate such a hypothesis, i applied the mesowear method to the last two upper and lower molars also with the aim of investigating whether results obtained by analysing these chewing teeth are consistent with each other and, therefore, may provide hints to infer dietary behaviour when the m2 sample is not statistically valid, and the wear variation is particularly high. 2. materials and methods the material object of this study is kept at the paleontological museum of the la sapienza university of rome and consists of 102 molars: 25 m2, 32 m3, 24 m 2 and 21 m3. i chose to analyse the upper and lower penultimate and ultimate molars because results provided by the two-tooth model (m2-m3) are similar to those obtained by analysing only m2 (franz-odendaal & kaiser, 2003), while the analysis of upper and lower m1 and p4 has been demonstrated to be less reliable (as least as ruminants is concerned, conversely to horses) (kaiser & solounias, 2003; kaiser, 2003; kaiser & fortelius, 2003) because of the extent of the wear period (see louys et al., 2011). only permanent teeth showing different wear stages have been considered. the sample does not include teeth in very advanced stage of wear. the shape of cusps of molars of deer from bate cave ranges from high and sharp in unworn teeth to low and rounded/ sharp in the most worn one. therefore, prior to performing the mesowear analysis, c. ex gr. c. ropalophorus molars were grouped according to their degree of wear. the wear classes were evaluated according the idas system (individual dental age stages) based on tooth eruption and tooth wear (anders et al., 2011) and the progressive decrease of crown height have been used as a guideline to define three wear stages: slightly worn teeth (1° wear stage, w1) (idas 2, permanent dentition is fully erupted), average worn teeth (2° wear stage, w2) (idas 3, the second molar starts to lose the inner profile), strongly worn teeth (3° wear stage, w3) (idas 4, the second molar loses the inner profile) (anders et al., 2011). it is well known that in herbivore the height of the tooth crown provides clues as regard to dietary aptitudes, because reflects the resistance of tooth to the abrasive power of food responsible for tooth wear during the masticatory process (i.e. herbivores feeding on fibrous material have a hypsodont dentition) (see inter alios fortelius, 1985; janis, 1988; janis & fortelius, 1988; damuth & janis, 2011; kaiser et al., 2013). the quantitative measure of hypsodonty, (hypsodonty index, hi) can be calculated in different ways: on m2 by dividing the height of the crown by the occlusal total length of the tooth (valli & palombo, 2008), and on m3 by dividing the height of the crown by width of the tooth (janis, 1988; fortelius & solounias, 2000; kaiser et al., 2013). appling both methods the value of the hi measured on unworn teeth is < 1.5 in brachydont, ranges from 1.5 to 3.0 in mesodont, and from 3.0 to 4.5 in hypsodont, and is > 4.5 in highly hypsodont animal. the hi of c. ex gr. c. ropalophorus has been evaluated measuring m2 and m3 at different wear stage. as regards to the parameters related to mesowear method (fortelius & solounias, 2000), the cusp height (occlusal relief-or) was defined as the difference in height between cusp tips and inter cusp valley as seen in labial projection (m2, m3) or in lingual projection (m2, m3). the or values is “high” when the result is greater than 0.1, while “low” when it is less than 0.1. the shape of the cusps was qualitatively evaluated according to three typologies: sharp, rounded, and blunt (fig. 2). all mesowear results was converted into mesowear score (kaiser et al., 2009) and plotted versus hi in order to verify whether this rating may be regarded as a valid habitat proxy (kaiser et al., 2013). data obtained for c. ex gr. c. ropalophorus have been compared with those of 63 extant species (data from fortelius & solounias, 2000; mendoza & palmqvist, 2008; kaiser et al., 2009; kaiser et al., 2013) (tab. 1). to infer the grazer versus browser ability of c. ex gr. c. ropalophorus from bate cave, a cluster analysis has been performed comparing c. ex gr. c. ropalophorus with 52 extant artiodactyl species (cervids, bovids, giraffids and camelids, data from fortelius & solounias, 2000; franz-odendaal & kaiser, 2003; louys et al., 2011) (tab. 2). the species were assigned to dietary categories on the basis of personal observation and comparing results obtained by different authors (fortelius & solounias, 2000; gagnon & chew, 2000; louys et al., 2011). four extinct species having different trophic and ecological requirement have been added to the cluster analysis (tab. 2) selected because they show a dietary behaviour of candiacervus ex gr. c. ropalophorus from bate cave (crete) 79 mesowear patter similar to that of c. ex gr. c. ropalophorus (duboisia santeng, metacervoceros rhenanus and croizetoceros ramosus) and because inhabited on a mediterranean island environments similar to those of the cretan deer (praemegaceros cazioti). two pleistocene insular species, praemegaceros cazioti from dragonara cave (sardinia) and duboisia santeng from java, and two continental villafranchian cervids metacervoceros rhenanus and croizetoceros ramosus from saint-vallier (drôme, france). the dwarf megacerine preamegaceros cazioti from dragonara cave (sardinia) was a mixed feeder inhabiting territories characterized by hard and bumpy substrate (caloi & palombo, 1991; mujica, 2014) and a vegetation cover comparable to the mediterranean scrub (palombo, 2005). the dwarf bovid duboisia santeng from java, was a forest dweller, mostly feeding on leaves and only occasionally on harder vegetation (rozzi et al., 2013). the metacervoceros rhenanus and croizetoceros ramosus villafranchian deer from sainttab. 2 the extant and fossils species were compared in this study by cluster analysis with candiacervus ex gr. c. ropalophorus from bate cave. tab. 1 date used for the construction of bivariate plot: dietary classification (dc); mesowear score (ms); hypsodonty index (hi); habitat categories (hab), 1=open, 2=intermediate, 3=closed. (data from fortelius & solounias (2000), kaiser et al., 2009, kaiser et al. (2013) and references therein). <<----------------------------------------- 80 altamura s. vallier (drôme, france) were seasonal mixed feeder with a mainly browsing feeding behaviour (valli & palombo, 2008). hierarchical cluster analysis was performed by means of past 3.13 software (hammer et al., 2001) with euclidean distances and complete linkage, using as variables the percentage of or and shape cusp resulting from mesowear analysis. three clusters analyses have been performed on three samples. in the first, cluster-a, m2 and the twotooth model approach were used irrespectively of the wear stage of c. ex gr. c. ropalophorus teeth. in the second, cluster-b, the last upper and lower molars are individually examined taking into account their wear stage. in the third, cluster-c, the two-tooth model was used, taking into account wear stage of the teeth. fig. 2 candiacervus ex gr. c. ropalophorus from bate cave (crete) (bate 6), fragment of the left maxillary with p2 m3 (on the left). the mesowear variables as in fortelius and solounias (2000) (on the right). fig. 3 upper and lower molars of candiacervus ex gr. candiacervus ropalophorus from bate cave (crete) grouped according to their wear stages: wear stage 1: a) third upper molar (labial and occlusal views); b) second lower molar (lingual and occlusal views); wear stage 2: c) third upper molar (labial and occlusal views); d) second and third lower molar (lingual and occlusal views); wear stage 3: e) second and third upper molar (labial and occlusal views); f) second and third lower molar (lingual and occlusal views). dietary behaviour of candiacervus ex gr. c. ropalophorus from bate cave (crete) 81 second lower molars (fig. 4). in teeth at first wear stage, cusps are in upper molars only sharp, while in the lower molars rounded cusps reach the 30%. as the degree of wear augments the shape of cusps changes from sharp towards lesspointed, the percentage of rounded cusps increases and some blunt cusps may be occasionally present. it is worth noting, however, that cusps are still evident even in the worn teeth. moreover, with the increasing of the wear degree, the percentage of the high cusps slightly decreases, but they are still the most abundant (fig. 5, tab. 5). the hi and ms values of the cretan small deer are very low. as regards to the clues about dietary behaviour (fig. 6) and habitat (fig. 7) obtained by plotting hi versus ms, the c. ex gr. c. ropalophorus sample fall in the ecospace of browsers and species prevalently inhabiting close environments. the cluster analysis provides a quite good resolution in splitting extant artiodactyl species according to their dietary adaptation (figg. 8a, b, c). three main groups are generally detectable, the first includes a high percentage of browsers, in the second includes mixed feeders and few browsers and grazers, in the third grazers dominate. in the cluster-a (fig. 8a), c. ex gr c. ropalophorus (crb)’s m2 falls in the mixed feeder spectrum (b.2) together with gazella granti (gg), which is a mixed feeder 3. results 3.1. wear stage in the first wear stage teeth show thin streaks of dentin. the cusps, paracone and metacone, are well defined and the median groove shows a marked "v" shape (fig. 3.a, 3.b). at the second wear stage, in the masticatory table the dentine area is wider and shows rhomboidal geometry. the infundibula are evident though reduced with respect to the previous stage, and still connected in the upper molars. the median groove is evident, but the outline is "u-shape". the cusps are still well defined (fig. 3.c, 3.d). in molars with an advanced wear degree, infundibula are greatly reduced, the dentine is exposed over the whole occlusal surface and the enamel band is thinner than that of previous wear stages. the bottom of the median groove can reach the neck, or even the roots. the cusps are still identifiable, the profile is angled or undulate, though height and shape of cusps show a quite significant variation (fig. 3.e, 3.f). 3.2. hypsodonty the average hi of c. ex gr. c. ropalophorus m2 and m3 shows values roughly consistent with each other, though hi values of m3 are generally higher than those obtained for m2. the lower third molar is, indeed, the last tooth to erupt and in extant deer the eruption is completed about 6-12 months (roe deer and red deer respectively) later than that of m2 (de marinis & toso, 2015). the average hi value in teeth at the first wear stage is < 1.5 confirming that c. ex gr. c. ropalophorus from bate cave has a brachyodont dentition (tab. 3). as expected hi decreases as the wear augments. as expected, the hi reduction is proportional to the degree of wear. furthermore, the differences in hi between teeth at the first and the second stage of wear (hi) is slightly greater in m3 than in m 2, while the differences are almost the same in m3 and m 2 at the second and third stages of wear. 3.3. mesowear patterns and dietary behaviour results obtained by the mesowear analysis on m2, m3, m2 and m3 of c. ex gr. c. ropalophorus from bate cave indicate that cusps have generally high (86%) and sharp/rounded (49%/48%) profiles (tab. 4). the sharp shape prevails in the second upper molar, while, rounded shapes are more frequent in the tab. 3 hypsodonty index in the last lower (m3) and second upper molars (m2) of candiacervus ex gr. c. ropalophorus from bate cave (crete), grouped according to their wear stage. tab. 4 summary of the percentage of mesowear variables in the molars of candiacervus ex gr. c. ropalophorus from bate cave (crete), overall and grouped according to their wear stage. tab. 5 percentage of mesowear variables in second and third upper and lower molars of candiacervus ex gr. c. ropalophorus from bate cave (crete), grouped according to their wear stage. 82 altamura s. but having a predominant browser behaviour (b.2.2.1.2). when the average value obtained from m2 and m3 analysis is considered (two-upper-tooth model), cretan deer still falls in mixed feeder field (b.2.2.1.2), close to m2 average value, together with ovibos moschatus (om) which is an opportunistic specie. when the average value obtained from m2 and m3 analysis is considered (two-lower-tooth model), c. ex gr c. ropalophorus falls between the mixed feeders (b.2.2.1.1) but close to antidorcas marsupialis (ma), which is an intermediate seasonal browser. in the cluster-b (fig. 8b), where the wear stages of c. ex gr. c. ropalophorus (crb) have been taken into account, two main groups are identifiable. a small group (a) including browsers, and a large one (b) gathering both mixed feeders (b.1) and grazers (b.2), which, however form two separate sister groups. the c. ex gr. c. ropalophorus m2, m3 (a.2.2) and m3 (a.1.2), at the first wear stage (w1) fall among browsers (a). in particular, m2 and m3 are linked with alces alces (aa), and m3 with odocoileus hemionus (oh), both typical browsers. conversely, m2 teeth fall among the mixed feeders (b.1.2.1.1) possibly because, although the cusps with a sharp shape predominate, the percentage of rounded cusps is not negligible (37.5%). the percentage of rounded cusps considerably increases in m2 at the third stage of wear, which fall in the grazer range (b.2.1.1.2) although the percentage of high cusps is unusually high (80%) for grazers. most of the other c. ex gr. c. ropalophorus molars, showing various degrees of wear, fall in the large group of mixed feeders together with species (e.g. gazella granti (gg), g. thomsonii (gt), g. dorcas (gd), ourebia ourebi (oo), tragelaphus strepsiceros (tt), t. imberbis (ti), but also ammodorcas clarkei (ei)) that mainly eat leaves, fruit, or fresh grass, according to the season and the availability of vegetal resources. in the cluster-c (fig. 8c), where only the two-tooth model with lower and upper molars of c. ex gr. c. ropalophorus (crb) from the first to third stage of wear have been included, the distribution of extant species belonging to the three main trophic groups is similar to that of cluster-b. as regards to cretan deer, molars at the first stage of wear fall in browser group (a), with alces alces (aa) and odocoileus hemionus (oh), while those at the second and third stage mainly fall among the mixed feeders tree. the sister group of the upper molars at the second and third wear stage and the lower molars at the third wear stage (b.1.1) includes gazella soemmerringi (gs), which feeds on bush leaves, grasses and herbs and g. dorcas (gd), which eats leaves, pods, fruits and bulbs. the lower molars at the second wear stage has as sister group (b.1.2.2.1) ovis canadensis (oc), which consumes leaves, grasses, sedges and forbs, but it usually takes some browse during winter, and gazella granti (gg), its diet consist mainly of leaves and stems. fig. 6 bivariate plot of mesowear score (ms) and hypsodonty index (hi) of extant artiodactyls and candiacervus ex gr. c. ropalophorus from bate cave (crete). data of extant species from fortelius & solounias (2000), kaiser et al. (2009) and kaiser et al. (2013) (tab.3). fig. 7 bivariate plot of mesowear score (ms) and hypsodonty index (hi) with habitat as cofactor of extant artiodactyls and candiacervus ex gr. c. ropalophorus from bate cave (crete). data of extant species from fortelius & solounias (2000), mendoza & palmqvist (2008), kaiser et al. (2009) and kaiser et al. (2013) (tab.3). dietary behaviour of candiacervus ex gr. c. ropalophorus from bate cave (crete) 83 fig. 4 comparison among the percentage of mesowear variables in second (m2u) and third (m3u) upper and lower (m2lm3l) molars of candiacervus ex gr. c. ropalophorus from bate cave (crete). fig. 5 comparison among the percentage of mesowear variables in upper and lower molars of candiacervus ex gr. c. ropalophorus from bate cave (crete) grouped according to their wear stage. f ig . 8 .a c lu st e ra : h ie ra rc h ic a l cl u st e r d ia g ra m c o m p a ri n g t h e o n e -t o o th m o d e l u si n g u p p e r se co n d m o la rs o n ly a n d t h e u p p e r a n d l o w e r tw o -t o o th m o d e l u si n g s e co n d a n d t h ir d m o la rs o f c a n d ia ce rv u s e x g r. c . ro p a lo p h o ru s fr o m b a te c a ve , b a se d o n a s e t e xt a n t a n d f o ss il sp e ci e s (d a ta f ro m f o rt e liu s & s o lo u n ia s, 2 0 0 0 ; f ra n zo d e n d a a l & k a is e r, 2 0 0 3 ; l o u ys e t a l., 2 0 1 1 ; p a lo m b o , 2 0 0 5 ; v a lli & p a lo m b o , 2 0 0 8 ; r o zz i e t a l., 2 0 1 3 ). t h e m e so w e a r va ri a b le s: p e rc e n t h ig h o cc lu sa l r e lie f, p e rc e n t sh a p e c u sp s (s h a rp , ro u n d e d a n d b lu n t) . b ro w se r= u p p e r c a s e a n d g re e n ; g ra ze r= lo w e r ca se a n d b ro w n ; m ix e d f e e d e r= m ix e d c a se a n d y e llo w ; f o ss il sp e ci e s= in ve rs e m ix e d c a se a n d p in k. c r b ( b lu e )= c . e x g r c . ro p a lo p h o ru s fr o m b a te c a ve . “d is ta n ce ” = e u cl id e a n d is ta n ce . 84 altamura s. f ig . 8 .b c lu st e rb : h ie ra rc h ic a l cl u st e r d ia g ra m c o m p a ri n g t h e o n e -t o o th m o d e l u si n g u p p e r a n d l o w e r se co n d m o la rs a n d u p p e r a n d l o w e r th ir d m o la rs g ro u p e d a cc o rd in g t o t h e ir w e a r st a g e o f c a n d ia ce rv u s e x g r. c . ro p a lo p h o ru s fr o m b a te c a ve , b a se d o n a s e t e xt a n t a n d f o ss il sp e ci e s (d a ta f ro m f o rt e liu s & s o lo u n ia s, 2 0 0 0 ; f ra n zo d e n d a a l & k a is e r, 2 0 0 3 ; l o u ys e t a l., 2 0 1 1 ; p a lo m b o , 2 0 0 5 ; v a lli & p a lo m b o , 2 0 0 8 ; r o zz i e t a l., 2 0 1 3 ). t h e m e so w e a r va ri a b le s: p e rc e n t h ig h o cc lu sa l re lie f, p e rc e n t sh a p e c u sp s (s h a rp , ro u n d e d a n d b lu n t) . b ro w se r= u p p e r c a s e a n d g re e n ; g ra ze r= lo w e r ca se a n d b ro w n ; m ix e d f e e d e r= m ix e d c a se a n d y e llo w ; f o ss il sp e ci e s= in ve rs e m ix e d c a se a n d p in k. c r b ( b lu e )= c . e x g r c . ro p a lo p h o ru s fr o m b a te c a ve . “d is ta n ce ” = e u cl id e a n d is ta n ce . dietary behaviour of candiacervus ex gr. c. ropalophorus from bate cave (crete) 85 f ig . 8 .c c lu st e rc: h ie ra rc h ic a l cl u st e r d ia g ra m c o m p a ri n g t h e u p p e r a n d l o w e r tw o -t o o th m o d e l u si n g s e co n d a n d t h ir d m o la rs a cc o rd in g t o t h e ir w e a r st a g e o f c a n d ia ce rv u s e x g r. c . ro p a lo p h o ru s fr o m b a te c a ve , b a se d o n a s e t e xt a n t a n d f o ss il sp e ci e s (d a ta f ro m f o rt e liu s & s o lo u n ia s, 2 0 0 0 ; f ra n zo d e n d a a l & k a is e r, 2 0 0 3 ; l o u ys e t a l., 2 0 1 1 ; p a lo m b o , 2 0 0 5 ; v a lli & p a lo m b o , 2 0 0 8 ; r o zz i e t a l., 2 0 1 3 ). t h e m e so w e a r va ri a b le s: p e rc e n t h ig h o cc lu sa l re lie f, p e rc e n t sh a p e c u sp s (s h a rp , ro u n d e d a n d b lu n t) . b ro w se r= u p p e r c a s e a n d g re e n ; g ra ze r= lo w e r ca se a n d b ro w n ; m ix e d f e e d e r= m ix e d c a se a n d y e llo w ; f o ss il sp e ci e s= in ve rs e m ix e d c a se a n d p in k. c r b ( b lu e )= c . e x g r c . ro p a lo p h o ru s fr o m b a te c a ve . “d is ta n ce ” = e u cl id e a n d is ta n ce . 86 altamura s. 4. discussion and conclusion results obtained by the mesowear analysis of molars of c. ex gr. c. ropalophorus from bate cave suggest a chewing activity mainly characterised by a friction action associated with a milder abrasive component. the latter becomes more relevant as the degree of wear increases, although, in the cusps are still well delineated (fig. 3.e, 3.f). therefore, it is rational to suppose that the chewing process of c. ex gr. c. ropalophorus may have taken place in two phases. in the first phase a sharing component prevails, while in the second the sharing is progressively lost and the grinding prevails (janis, 1979; valli et al., 2012). the abrasive component equals or prevails over the frictional one if the wear is advanced. however, even at the third wear stage sharp cusps are still present (25%), suggesting that c. ex gr c. ropalophorus likely had an intermediate-browser feeding behaviour. the variation of hi at different wear stage is not particularly high being the value of hi at the last stage 58% less than at the first. it is worth noting that the typology of food may greatly affect brachyodont teeth, resulting in premature loss of its functionality (anders et al., 2011). in deer, the extent of the wear stages is not characteristic of a species, conversely intraspecific variation has been observed according to the environmental characteristic and the resources availability. accordingly, the variation in hi shown by c. ex gr. c. ropalophorus molars may be regarded as coherent with a diet consisting in no-abrasive food. this conclusion is supported by cluster analysis. the results obtained indicate that the small deer from bate cave had an intermediate-browser feeding strategy (mixed-feeder versus browser) and the diet possibly included more leaves and buds than hard grasses. the inferred feeding behaviour is supported by the cranial and mandibular features related to masticatory processes (see caloi & palombo, 1996 for a discussion). in addition, it is interesting to note how mesowear pattern slightly differs in upper and lower molars having similar wear degree (fig.8b). the cusps of second lower molar, indeed, are generally less sharp then those of last molars (tab. 5), as indicate by the position of m2 (w1-w2-w3), which mainly fall among mixed-feeder, at the first and second stage of wear, and among grazers at the third stage. this result confirms for m2 what observed by kaiser & fortelius (2003) and franzodendaal & kaiser (2003) in some herbivores. differences in the mesowear pattern shown by upper and lower cheek teeth may depend on the fact that during the masticatory process food frequently is more in contact with the lower teeth than with the upper ones. the degree of functional anisodonty and differences in mesowear pattern seem to be more pronounced in mixed feeders then in specialized feeders, though such differences are less evident when a two-tooth model is applied (fig. 8c). all in all, the obtained results indicate that c. ex gr. c. ropalophorus from bate cave had an opportunistic eating habit with a prevalent browser behaviour. these small deer on one hand possibly had a remarkable ability to select the food and change their diet according to the nature and number of competitors, the environmental characteristics and their seasonal changes, on the other they likely did not inhabited environments with a low primary productivity. acknowledgements i thank the director and staff of the paleontological museum of sapienza university of rome for giving me access to deer collections and their assistance during my research. i’m grateful to a.m.f. valli and the anonymous reviewer for their useful comments, and to m.r. palombo for suggestions and valuable discussion. this research was funded by italian murst (sapienza university of rome 2014, project c26a14bnrm led by m.r. palombo). references anders u., von koenigswald w., ruf i., smith b.h. 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(2012) how homogeneous are microwear patterns on a fossil horse tooth? preliminary test on a premolar of equus altidens from barranco leon 5 (spain). amqalpine and mediterranean quaternary, 25, 1, 25-33. yamada e. 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can be opened with acrobat and adobe reader 5.0 and later.) >> /namespace [ (adobe) (common) (1.0) ] /othernamespaces [ << /asreaderspreads false /cropimagestoframes true /errorcontrol /warnandcontinue /flattenerignorespreadoverrides false /includeguidesgrids false /includenonprinting false /includeslug false /namespace [ (adobe) (indesign) (4.0) ] /omitplacedbitmaps false /omitplacedeps false /omitplacedpdf false /simulateoverprint /legacy >> << /addbleedmarks false /addcolorbars false /addcropmarks false /addpageinfo false /addregmarks false /convertcolors /converttocmyk /destinationprofilename () /destinationprofileselector /documentcmyk /downsample16bitimages true /flattenerpreset << /presetselector /mediumresolution >> /formelements false /generatestructure false /includebookmarks false /includehyperlinks false /includeinteractive false /includelayers false /includeprofiles false /multimediahandling /useobjectsettings /namespace [ (adobe) (creativesuite) (2.0) ] /pdfxoutputintentprofileselector /documentcmyk /preserveediting true /untaggedcmykhandling /leaveuntagged /untaggedrgbhandling /usedocumentprofile /usedocumentbleed false >> ] >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice amq28(2)131-143 toti rivisto 12_2015 edi.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 28 (2), 2015, 131 143 interglacial vegetation patterns at the early-middle pleistocene transition: a point of view from the montalbano jonico section (southern italy) francesco toti department of earth sciences, university of florence, florence, italy corresponding author: f. toti <francesco.toti@unifi.it> abstract: the montalbano jonico succession (southern italy) represents a rich stratigraphic archive of the early to middle pleistocene environmental and climatic changes in the central mediterranean. pollen analyses associated to multivariate statistical methods (principal component and cluster analyses) have been carried out in the sedimentary portion including marine isotope stages (mis) 21 to 17 (~200 kyrs and ~190 m). the pollen ratio between mesotherm and steppic taxa (pollen temperature index), used as a proxy of temperature, permits to precise consecutive warmer and cooler phases associated, respectively, to interglacials/interstadials and glacials/stadials (substages 21.3 to 18.3 plus stage 17). pollen data suggest major expansions of mixed oak forests during warm phases, whereas open vegetation typically marks cool to cold phases. the statistical processing puts in evidence both analogies and differences among the successive interglacials/interstadials. midto high-altitude trees and mediterranean taxa appear to expand slower than hydrophytes plus deciduous oaks and other herbs, which conversely act like pioneers. moreover tsuga, cedrus plus steppic plants and poaceae are inversely related to mediterranean xerophytes and mesotherm deciduous taxa, possibly due to the different tolerance to temperature decreases. on this basis, three main vegetation patterns seem to occur during warm periods. the 1st pattern (including mis 21.3, 19.3 and 17) shows a tripartite structure with a middle warm phase including higher abundances of slow-spreading taxa, sandwiched between cooler intervals (at the beginning and the end of the sub-stage) with the increase of faster-expanding taxa. the 2nd pattern (in mis 21.1 and 19.1) shows a complex structure characterized by rapid changes in proportions between fastand slow-spreading taxa as well as among plants with different tolerance to temperature decrease. the 3rd pattern (in two interstadials within mis 18), is characterized by relatively high abundances of fast-spreading taxa and low abundances of warmth-demanding taxa. this work represents a first attempt for a better understanding of interglacial vegetation dynamics during the early-middle pleistocene transition; deeper investigations are in progress with the specific aim to better characterize the observed multiple patterns and possibly to define their causes. keywords: early-middle pleistocene transition, interglacials, mis 19, montalbano jonico, southern italy, principal component analysis, pollen analysis. 1. introduction during the transition between early and middle pleistocene (empt, 1.2-0.5 ka; e.g. head & gibbard, 2005; maslin & ridgwell, 2005), earth’s climate experienced a gradual change in the glacial-interglacial (g-i) oscillations mode. the orbital obliquity-driven 41 kyrs cyclicity, which had dominated the earlier part of the pleistocene, was overshadowed by a high-amplitude, lower-frequency 100 kyrs-rhythm. a profound impact on terrestrial and marine biota is recorded across the empt as a result of changes in the intensity and duration of both glacials and interglacials (e.g. head et al., 2008). in the italian pollen and calcareous nannoplankton records a major shift seems to coincide with the marine isotope stages (mis) 25 to 20, at the end of the jaramillo sub-chron, where several turnovers in the nannofossil communities and the progressive disappearance of the most thermophilous pollen taxa occurred (bertini et al., 2010 and references therein). on the other hand, no remarkable events have been recorded at the calabrian-ionian transition (e.g. head & gibbard, 2005; bertini et al., 2015). quaternary european and mediterranean pollen records display recurrent patterns of vegetation succession paralleling g-i cyclicity. in italy, four main patterns have been summarized on the basis of latitudinal, geomorphological and local factors by bertini (2010). pattern 1, is expressed by open vegetation-thermophilous forest alternations especially in mediterranean littoral zones (e.g. suc et al., 1995). pattern 2, which is typical of several northern apennines sites, exhibits prevalent alternations between altitudinal coniferous and thermophilous forests (e.g. bertini 2001 and references therein). patterns 3 and 4 show the presence of thermophilous and coniferous forest, respectively, during glacials, and open vegetation and steppe, respectively, during interglacials (e.g. bertoldi et al., 1989; capraro et al., 2005). the interglacial structure, its duration and intensity, as well the seasonality, strongly depend on the earth orbital geometry, which is a major factor of climate forcing (e.g. hays et al., 1976; berger, 1981; 1988). according to many authors, the vegetation succession of each interglacial is “unique” because of the peculiar combination of its astro -climatic variables (e.g. watts, 1988; bartlein & prentice, 1989; huntley & webb, 1989). moreover, even where some interglacials exhibit virtually identical orbital configurations, the occurrence of stochastic factors (e.g. relationships among taxa and/or between taxa and climate) can make the system unpredictable (e.g. bennett et al., 1991; tzedakis et al., 2012a). at the same time, the existence of interglacials characterized by very different climate conditions but showing similar vegetation patterns cannot be excluded (tzedakis & bennett, 1995); in this case, internal biotic forcings should be invoked. one of the longest composite quaternary pollen record, including subsequent interglacials since the base of the gelasian, has been reconstructed by the study of both marine and continental successions of southern italy (fig. 1) (e.g. combourieu-nebout et al., 1990; combourieu nebout and vergnaud grazzini, 1991; combourieu-nebout, 1993; capraro et al., 2005; klotz et al., 2006; joannin et al., 2008; russo ermolli et al., 2010a, b, 2014; suc et al., 2010; amato et al., 2014; petrosino et al., 2014; robustelli et al., 2014; bertini et al., 2015; marino et al., 2015). the knowledge of past interglacials is particularly significant not only because it allows the documentation of ancient paleoenvironments but also for its key role in modeling the natural course of the present interglacial (holocene), permitting predictions about the future climate changes. for this study a selected portion of the montalbano jonico (mj) section, spanning the mis 21-16, has been submitted to detailed palynological analyses which have strongly improved those recently produced in bertini et al. (2015), and extend the previous pollen documentation concerning mis 3723 (joannin et al., 2008). the main purpose of this paper is to recognize similarities and differences in the vegetation dynamics between subsequent warm periods (either interstadials or interglacials), assuming that each one is marked by a peculiar astronomical and vegetation signature. to achieve this aim, warmer phases have been singled out and compared using a multivariate statistical approach. the significance of the mj pollen record is enhanced by the possibility to exclude the presence of consistent stratigraphic gaps thanks to the strong stratigraphical frame established for this marine section (e.g. marino et al., 2015 and references therein). 2. case study: the montalbano jonico section 2.1. geological and stratigraphical setting mj composite succession is located in the basilicata region (southern italy), near the eponymous village, at 40°17’n 16°34’e (292 m above the sea level). its deposition occurred within the bradanic foredeep, a perisutural basin bounded westward by the apennine orogenic front and eastward by the murge highlands. the mj succession covers more than 630 kyrs (lower to middle pleistocene; ciaranfi et al., 2010) and has been reconstructed sewing up 10 sub-sections (ciaranfi et al., 1997; 2001). the succession is divided in two distinct portions by a stratigraphic gap (fig. 2). the lower portion (“interval a”) consists of ~180 m thick muddy turbidites including a volcaniclastic layer (v1). benthic paleocommunities assign “interval a” to an upper-slope environment involved in a prevalent shallowing upward trend (d’alessandro et al., 2003; stefanelli, 2004). the upper portion (“interval b”) is more than 300 m thick and includes silty sands and silty clays in which eight volcaniclastic layers (v2-v9) are embedded; repeated deepening-shallowing cycles, from outer to inner shelf environment, have been recognised (d’alessandro et al., 2003; stefanelli, 2004) (fig. 2). bathymetric changes have been firstly related to the north-eastward thrusting of the southern apennines units (ciaranfi et al., 1996; d’alessandro et al., 2003), and secondly to the orbital-scale g-i ciclicity and climate-driven eustatic variations, in the frame of the progressive pliopleistocene cooling (e.g. joannin et al., 2008; ciaranfi et al., 2010). based on the most recent radiometric datings 132 toti f. fig. 1 (a) location of montalbano jonico and the main sites of southern italy cited in the text. (b) view of the montalbano jonico succession in the “calanchi” badlands area, with the agri valley in the background. (39ar/40ar) on v1-v5 tephra layers (petrosino et al., 2015) and the constrains provided by the calcareous plankton (maiorano et al., 2004), sapropel (stefanelli et al., 2005) and isotopic (brilli et al., 2000) stratigraphy, marino et al. (2015) have proposed the age-model shown in fig. 2, closely related to the astronomical tuning of the section by ciaranfi et al. (2010). correlations with lr04 benthic stack (lisiecki and raymo, 2005), pacific (mix et al., 1995a,b; shackleton et al., 1995) and atlantic (bickert et al., 1997) δ18o benthic records allow the isotopic shifts related to mis 22-16 to be outlined (ciaranfi et al., 2010; marino et al., 2015). according to the calcareous plankton-inferred relative chronology (maiorano et al., 2004), “interval b” extends from the top of pseudoemiliania lacunosa zone to the base of emiliania huxleyi zone of rio et al. (1990) (fig. 2). two nannofossil events are recorded: the beginning (826.89 ka) and the end (771.04 ka) of the second temporary disappearance of gephyrocapsa omega (maiorano et al., 2004). although no sapropels occur within the 133 interglacials at the empt in southern italy fig. 2 lithostratigraphy and benthic δ18o record of the montalbano jonico composite section (brilli et al., 2000; ciaranfi et al., 2010; maiorano et al., 2010; marino et al., 2015); the age of volcaniclastic layer v4 is after petrosino et al. (2015); the studied portion is indicated on the right. (modified from bertini et al., 2015). “interval b” (stefanelli et al., 2005), three bands with higher organic carbon content are visible (fig. 2): the oldest one encloses v4 tephra (773.9 ±1.3 ka, petrosino et al., 2015), the second and last one are located below and above the end of the second temporary disappearance of gephyrocapsa omega. the present work is based on the study of eightythree palynological samples from the 67.7 m (858 ka, mis 21)-257.5 m (656.05 ka, mis 16) portion of “interval b” (fig. 2), this generating a mean time resolution of ~2463 years. however this result is based on highly uneven values throughout the succession, ranging from 60 years to more than 14 kyrs. 2.2. present climate and vegetation the mj section lies between the metapontine jonian coast, to the south-east, and the agri valley, to the north-west. the latter is part of a wider hydrographic basin including all the apennines rivers with drainage towards the taranto gulf (fig. 1). the agri valley is bordered northward by reliefs ranging from ~1700 to ~2000 m. 50 km southwest of mj, the pollino massif, with several peaks over 2000 m, separates basilicata from calabria region. the agri valley approximates the intersection between three climatic zones: the coastal metapontine area, characterized by a meso-mediterranean regime, the eastern hinterlands, with semi-continental climatic features, and the western mountain area, with rainfalls well distributed throughout the year and strong thermal and humidity gradients depending on orography. the mj section is embedded in the evocative badlands landscape, molded by the erosion of pliopleistocene marine clays. the vegetation cover is firstly influenced by edaphic factors, being the substrate the result of sediment weathering (di pietro et al., 2004). halo-xerophytic components, such as camphorosma monspeliaca, lygeum spartum and mantisalca duriaei, colonize the steepest slopes, enriched by sulla coronata when slopes are weaker. terophytes grow in more sandy and detritic soils (fascetti et al., 2001). amaranthaceae (i.e. camphorosma, atriplex, suaeda) occupy flat and more humid zones at the base of the slopes. in weakly steep areas, poorly affected by erosion processes, terophytic fabaceae (including hedysarium and scorpiurus) dominate the floristic assemblage, with sporadic ingressions of plantago afra. on flat to sub-flat surfaces, some patchy mediterranean maquis occurs; here pistacia lentiscus dominates in association with rubia peregrina, phillyrea latifolia, juniperus oxycedrus, asparagus acutifolius and helictotrichon convolutum (biondi et al., 1992; fascetti et al., 2001). the basal horizon of the surrounding relief, which extends from a few meters to 300-400 m, belongs to the olive tree-carob tree alliance (mediterranean climax), also including holm oak; it is worth noting that the latter is an important component of higher (submontane) belts, forming mid-altitude (up to 800-1000 m) woodlands (corbetta, 1974). cypresses and aleppo pines occur as reforestation elements. submediterranean to submontane horizons are marked by the presence of quercus pubescens, commonly with fraxinus ornus (plus ostrya carpinifolia, carpinus betulus and c. orientalis in moisture-rich stations), pyrus communis, sorbus domestica, crataegus oxyacantha, ligustrum vulgare, spartium junceum, osyris alba, and sclerophyll taxa such as asparagus acutifolius and pistacia terebinthus. at higher elevations quercus pubescens tends to be replaced by q. cerris, which, together with chestnut woods, characterizes the submontane horizon. beechwoods and abies alba relict formations punctuate mountain belts, together with pteridium aquilinum brackens. the undergrowth composition varies with the altitude and includes noteworthy taxa such as ilex aquifolium, geranium striatum, and stellaria nemonum (corbetta, 1974). 3. methods 3.1. palynological analyses palynological analyses have been performed on samples from the mj section’s “interval b” (“ideale”, “js” and “vct” sub-sections: see fig. 2) during the first year of phd of the author; the pollen study is still in progress in order to increase the resolution in selected intervals. at present, eighty-three sediment samples have been processed using a standard palynological technique, at the laboratory of palynology of the department of earth science of the florence university. samples have been first weighted before starting the physical-chemical treatment. lycopodium tablets have been added to each sample to estimate palynomorph concentrations. attacks with acid (hcl and hf), koh and hexametaphosphate solutions have been followed by enrichments procedures (zncl2 and 10µm sieving in ultrasonic bath). residues have been mounted in slides using glycerol and finally analyzed by optical microscope (using x750 and 1250 magnifications) for quantitative pollen analyses. a mean of 284 pollen grains per sample have been counted, pinus and cupressaceae excluded. pinus, which is generally over-represented in the marine sediments (heusser, 1988; beaudouin et al., 2005), at mj reaches very high percentage values and for this reason has been excluded from the total pollen sum (see pollen diagram in fig. 3); for the taphonomic and palaeoenvironmental significance of pinus pollen grain, see bertini et al. (2015) and marino et al. (2015). cupressaceae pollen grains have been also removed from the total pollen sum as they exhibit in some levels both very high frequencies and morphologic features which do not support their unequivocal determination. pollen data are expressed as percentages normalized to the total pollen sum, excluding pinus, cupressaceae, indeterminate and indeterminable grains; the summary pollen diagram (fig. 3) shows eleven selected informal pollen groups established on the basis of climate and ecological requirements of correlative modern taxa, which are: (1) cedrus and tsuga; (2) high-altitude taxa (abies and picea plus betula and fagus); (3) deciduous quercus; (4) broad-leaved deciduous taxa minus quercus, e.g. carpinus, ostrya, alnus, ulmus, zelkova, alnus, carya, pterocarya, ericaceae and hedera; (5) mediterranean sclerophyll taxa, e.g. quercus ilex type, olea, pistacia and cistaceae; (6) asteraceae except artemisia; (7) poaceae; (8) hydrophytes, principally cyperaceae and sparganium/typha angustifolia type; 134 toti f. (9) halophytes, e.g. amaranthaceae, caryophyllaceae and plumbaginaceae; (10) steppic taxa, e.g. artemisia and ephedra; (11) other non-arboreal plants, e.g. brassicaceae, dipsacaceae, plantago, rosaceae and saxifragaceae. arboreal pollen (ap) relative abundances have also been plotted (fig. 3) as they are expected to reflect the spreading/shrinkage of the woodland in response, respectively, to the increase/decline of the atmospheric humidity. in order to discriminate warm (temperate) from cooler to cold phases, a pollen-derived palaeotemperature index (pollen temperature index: pti, fig. 3; e.g. joannin et al., 2008, 2011; bertini et al., 2015) has been used. pti, which is given by the ratio between mesothermic and steppic taxa, puts in evidence the glacial/stadial (lower values)-interglacial/interstadial (higher values) alternation in the pollen record. we have included deciduous quercus, corylus, carpinus, ostrya, alnus, ulmus, zelkova, carya, pterocarya, tilia, hedera and ericaceae (just to mention the most abundant) among mesothermic taxa and artemiasia, ephedra, lygeum and hippophae among steppic taxa. a threshold-value of the pti has been proposed at ~2 to divide warmer by cooler phases, so that they have distinct separations (fig. 3). the so defined glacial/stadial (pti < ~2) and interglacial/interstadial (pti > ~2) phases are in good agreement in terms of both chronologic position and time extension with the major shifts in the δ8o curve (e.g. sub-stages 21.3, 21.1, 19.3 and 19.1 after: marino et al.; 2015) of the same succession. 3.2. multivariate statistical analyses pollen data relative to the samples with a pti > ~2 (assumed to belong to interglacials/interstadials, as described in methods), in which the variables are represented by the eleven (1-11) selected informal groups, have been examined through principal component analysis (pca) using variance-covariance matrix as data input. pca has been adopted as a tool for transposing the original dataset variability in a lower dimension representation. in this simplified panorama, few principal components are assumed to summarize the associations among correlated variables. centered logratio transformation as proposed by aitchison (1982) have been carried out to avoid biases deriving from the compositional (constrained) nature of the data. variability similarities between selected pollen groups have been also evaluated through hierarchical cluster analysis, that has been applied on log-centered variables by using the euclidean distance as similarity measure andward's method as the subsequent linkage algorithm. 4. results palynological analyses point out a rich flora consisting of more than 120 taxa. they are largely herbaceous; among them asteraceae, poaceae, amaranthaceae and ephedra are dominant. artemisia and ephedra show subsequent phases of significant increase, reasonably linked to steppe expansion during (cold/dry) glacial periods at the expenses of forest taxa, amaranthaceae usually paralleling the steppe taxa trends (fig. 3). among arboreal taxa, pinus pollen grains reach the highest percentage values. quercus is also well represented and its increase has been associated to the expansion of the forest during warm-temperate conditions. among the other deciduous broad-leaved taxa, carpinus 135 135 fig. 3 pollen temperature index (pti) and percentage values of selected pollen groups in the mis 21-17 interval of the montalbano jonico section. on the left, the age-model (marino et al., 2015) and the benthic δ18o curve (brilli et al., 2000; ciaranfi et al., 2010). the horizontal dashed lines define informal pollen zones corresponding to the successive warm periods (i.e. zones i-vi plus t), as specified in the column on the right. ap: arboreal plants. interglacials at the empt in southern italy betulus, c. orientalis/ostrya type, ulmus, zelkova, etc. follow. along with zelkova, other taxa which progressively disappears in the course of the pleistocene, such as carya, pterocarya and liquidambar, are still found in this portion of the mj section, where taxodium type shows scattered occurrences. cedrus and abies are the most abundant taxa among midand highaltitude conifers, respectively. as a whole the floristic composition at mj is quite uniform as pointed out and discussed for the mis 21 to mis 18 interval by bertini et al. (2015); in fact neither disappearance nor appearance events have been recorded. 4.1. vegetation and climatic signature of interglacials and interstadials the subsequent changes in the arboreal and non-arboreal pollen taxa throughout the mj succession (858 to 656.05 ka) permit to recognize a clear alternation between forest and open landscapes. they are well expressed especially by the contraposition between steppe plus other nonarboreal taxa and quercus plus other mesophilous taxa (fig. 3). based on these vegetation data, it is possible to discriminate between warmer and cooler phases. it is further possible to determine the extension of such zones through the pti. in fact, as specified in methods, pti values higher than ~2 have been assumed to depict warm-temperate conditions associated to interglacials/interstadials whereas values lower than ~2 approximate glacials/stadials (fig. 3). forty-three samples have been thus included into seven informal “warm” zones: those labeled with roman numbers (i-vi) include samples with pti stably above 2, whereas that labeled with t (=transition) includes samples with pti quickly oscillating between 1.3 and 3 (fig. 3 and tab. i). each zone can be generally correlated with a stage or sub-stage of the marine isotope stratigraphy by considering the astronomical tuning after marino et al. (2015) and the oxygen isotope stack after bassinot et al. (1994) (fig. 3). a short description of the informal zones is provided below. zone i it is described by three pollen samples covering ~12 kyrs. ap percentages are constantly high, even if changes in proportions between midto high-altitude trees and mesophilous taxa pollen are recorded. zone i is consistent with mis 21.3. zone t ap are in low percentages, with a main fall at 827.5 ka. both steppic and halophytic taxa reach a peak at 824.5 ka. short-term variations of cedrus and tsuga diffusely occur. this zone correlates with sub-stage 21.1. zone ii mesophilous arboreal taxa show quite high percentages, decreasing only in correspondence with two short-term events (at 783.5 and 774.8 ka, bertini et al., 2015) marked by the expansion of asteraceae due to humidity drops. mediterranean taxa show a significant abundance at 780.56 ka, predating the acme of quercus and a subsequent increase of high-altitude taxa. this zone correlates with isotopic sub-stage 19.3. zone iii the first portion of the interval is marked by a positive excursion of oak and mediterranean taxa. afterwards, the other mesophilous taxa plus the midto highelevations trees slightly increase. a correlation of this zone with mis 19.1 is consistent. zone iv as a whole ap percentage values are similar to those of the previous zone iii (tab. i).the ap curve shows a peak centered at 741.41 ka. such an event coincides with an increase in midto high-altitude taxa and predates the start of quercus increase at 740.12 ka. the zone extension ranges between 18.4 and 18.3 isotope sub-stages. zone v ap percentages stay quite similar to those of the previous zones. quercus relative abundances rapidly increase between 728.28 and 726.9 ka, with secondary superimposed oscillations well appreciable due to the high time-resolution. a correlation with the 18.3 isotope sub-stage can be proposed. zone vi it corresponds to mis 17 and represents the longest interglacial. it is also marked by the highest ap values (a huge shift is located at 675.42 ka). between 697.31 and 677.96 ka, high-altitude taxa are considerably abundant, whereas cedrus and tsuga show sparse occurrences. mediterranean taxa peak at 695 ka, while deciduous quercus is involved in a gradual increase up 136 toti f. tab. i montalbano jonico section: pollen-based zonation for the studied interval, associated with summary vegetation indexes. correlation with isotopic stages is also shown. tab. ii montalbano jonico section: principal component loadings for the first three axes. to 680.69 ka, followed by a dramatic rise 5 kyrs after, when high-altitude elements collapse. 4.2. principal component analysis statistical calculations on selected pollen data allow three principal components to be extracted. they are able to take into account for about 69% of the total variance, thus providing a reasonable summary of the information contained in the dataset (tab. ii). the first principal component (pc 1) encloses 30.62% of the total variance and expresses a balance in which hydrophytes, quercus, poaceae and steppic taxa (with positive loadings) are opposed to tsuga and cedrus, highaltitude taxa and mediterranean taxa (with negative loadings). pc 1 could reflect the different timing of expansion exhibited by taxa with positive loadings (fasterexpanding taxa) versus negative loadings (slowerexpanding taxa). the analysis of vegetation successions in many sites of southern europe with sufficient moisture availability confirms that non-synchronous taxa expansions occur at the onset of warm-humid periods. deciduous quercus often expands early, followed by other mesophilous trees, such as carpinus and ostrya, and then by abies, fagus and sometimes picea (tzedakis, 2007; brauer et al., 2007). in fact, some waterdemanding arboreal taxa can show delays in migration 137 interglacials at the empt in southern italy fig. 4 montalbano jonico section: plot of sample scores. (a) first vs second principal component, (b) first vs third principal component and (c) second vs third principal component. samples colours indicate the correspondent pollen zone. because they require well developed soils, which do not form until several millennia from the beginning of an interglacial; conversely, deciduous oaks can grow on less organic soils (sadori et al., 2011). further, we may expect that hydrophytes and other herbaceous taxa react more rapidly to an increase of humidity with respect to arboreal taxa. the second principal component (pc 2) accounts for the 27.73% of the total variance, and expresses a balance between mid-altitude taxa, halophytes, steppic taxa (with positive loadings) and mediterranean elements, quercus, plus other broad-leaved thermophilous trees (with negative loadings) (tab. ii). conceivably, this balance can be considered expression of the differential vegetation’s response to cooler (with mid-altitude taxa and herbs increase) and warmer (with broad-leaved deciduous taxa and mediterranean xerophytes increase) climate contexts. the third principal component (pc 3), contributing for the 10.89% to the total data variability, appears to be almost exclusively controlled by high-altitude taxa (with positive loadings) and mediterranean taxa (with negative loadings). this component can reflect the different moisture requirements of mediterranean sclerophylls (adapted to seasonal draught) and high-altitude trees (demanding more constant humidity). samples from the seven statistical units associated with zones i-vi and t, plotted as scores (the coordinates of the samples in the space of the components) on the three main components (fig. 4) show scattered distributions and overlapping domain areas. in other words, “warm” zones, regarded as groups of samples defined a priori, cannot be discriminated if the variance-covariance structure of taxa groups is applied. 4.3. cluster analysis cluster analysis on the centered-log data has therefore been run in order to discover the presence of natural associations in the dataset. the obtained dendrogram (fig. 5a) permits to point out the presence of two well distinct groups of samples, marked with different colors (blue cluster vs green cluster) which further help us to sight them across the seven “warm” zones (fig. 5b). the main clusters obtained have been separated by considering that theiroccurred only for a high rescaled distance representing anof high dissimilarity. the two clusters have been then plotted as scores on the three main components revealed by multivariate analysis (fig. 6). in fig. 6a we can see that pc 1 and pc 2 are both involved in marking the separation between the two clusters. the blue cluster shows higher values for both axes with respect to the green cluster. in fig. 6b the two clusters are plotted in a pc 1 vs pc 3 diagram, and discrimination is 138 toti f. fig. 5 (a) cluster analysis on the selected warm periods from the montalbano jonico record; dendrogram has been obtained using ward method. (b) clustered samples are sorted in function of the age. fig. 6 montalbano jonico section: plot of sample scores on the component axes already used in fig. 4. samples are marked with colours of natural associations revealed by the cluster analysis. operated by the former. again, the blue cluster assumes higher values than green cluster. no significant discrimination is obtained by plotting the samples in a pc 2 vs pc 3 diagram. 5. discussion palynological analyses point out, in agreement with the isotopic record (marino et al., 2015), the succession of climatic oscillations between mis 21 and mis 16. in particular interglacials and interstadials are well expressed by major increases in deciduous quercus and other mesophilous taxa and by pti values higher than ~2. on the other hand, glacials and stadials are characterized by the large expansion of steppe and halophytic taxa as well as by pti values lower than ~2. cluster analysis on the pollen samples from the “warm” zones (i-vi plus t) indicates that the variability in taxa percentages is expressed by two main associations of samples (i.e. blue and green clusters), showing well sorted distributions on the pca plots (fig. 6a and b). each studied interval (zones i-vi and t) includes samples associated to both blue and green cluster, except for the zone v, wich is exclusively represented by blue cluster’s samples (fig. 7). a first observation is that a similar “blue-green-blue” arrangement unites zone ii and zone vi (mis 19.3 and 17, respectively) (fig. 7). (zone i represents the last ~12 kyrs of mis 21.3 and shows a pattern very close to those better expressed in both zone ii and zone vi). analogies can also be recognised between zone iv and zone v (mis 18.3-18.4 interval and mis 18.3, respectively), since they both show the predominance (up to totality) of “blue” samples (fig. 7). instead zone t and zone iii (mis 21.1 and 19.1, respectively) show a thickly alternate blue-green pattern. key remarks arise when samples are plotted into the pc 1 vs pc 2 diagram (fig. 6a). increasing values of the pc 1 highlight major differences on the rapidity of plant community changes: hydrophytes and deciduous quercus as well as other herbaceous taxa (with positive loadings), are expected to react more quickly to palaenvironmental changes than midto high-altitude forest taxa and mediterranean sclerophylls (with negative loadings) (tab. ii). on the other hand, the pc 2 can be thought to reflect the duality among plants with different tolerance to cold: tsuga, cedrus, halophytes and steppic taxa with positive loadings -, though diffused in very different environments, can tolerate decrease in temperature; conversely, mediterranean taxa and deciduous broad-leaved elements with negative loadings have a lower tolerance to temperature decreases. blue cluster’s samples are marked by higher values for both principal component axes than green cluster’s samples (fig. 6a). hence, the former reflect periods marked by (a) not very high temperatures (higher values on pc 2) and (b) the increase of fast-spreading taxa (higher values on pc 1); vice versa, the latter suggest contexts with (c) higher temperatures (lower values on pc 2) and (d) lower abundances of pioneer taxa (lower values on pc 1). this allow some considerations to be made, in the light of the three pattern previously described: vegetation succession during mis 19.3 and 17 (and possibly 21.3) is characterized by a warm mid-phase with a relatively high percentage of slow-spreading taxa, rimmed by cooler intervals with higher abundance of fast-expanding plants (sandwich pattern). the vegetation landscape within mis 21.1 and 19.1 constantly changes from warmer states, with the increase of slow-spreading taxa, to cooler states, in which higher frequencies of fast-spreading taxa are recorded. interstadial between mis 18.4 and mis 18.3, as well as mis 18.3, show a rather monotonous vegetation pattern, marked by the constant relatively low presence of both slow-spreading and warmth-demanding taxa. this is probably due to the shortness of the warm phase that prevent those plants to settle. selected warm periods at mj section, “interval b” are different under many points of view, being their duration, time-scale position, intensity and orbital configurations widely varying. nevertheless, cluster analysis shows that the most of the variability is described by only two main classes of samples, which generally coexist within each interval. at one level, warm periods globally show more similarities than initially predicted. as hinted by tzedakis & bennet (1995), internal biotic factor such as interand intra-specific competition can be invoked to justify these analogies. at the same time, it is worth nothing that each period is characterized by a specific vegetation dynamics (see the presence of three patterns), which induce to stress the role of the forcing by external factors. 6. conclusions and perspectives mj section represents an important stratigraphic archive for the reconstruction of the early-middle pleistocene g-i cycles in the central mediterranean basin. indepth studies on flora and vegetation changes have been previously carried out by joannin et al. (2008) and bertini et al. (2015), for the mis 37-23 and mis 21-18 intervals, respectively. here, high resolution palynological analyses and statistical processing of pollen data have been performed for the interval mis 21 to 16. such an approach has permitted to characterize and compare successive warm periods in terms of duration, intensity and vegetation dynamics. the pca carried out on pti-based statistical groups has not permitted to discriminate the different warm periods. on the other hand, cluster analyses underline the presence of two natural association of samples, which bear vegetational signatures when they are plotted on principal component axes. such a double type of samples is not randomly arranged across the succession and points out three main pattern in the warm periods. since the age-model of the mj section allows correlations with the orbital geometry predicted for each period (e.g. after laskar et al., 2004), it would be possible to verify if astronomical forcing can be (at least partially) responsible for the different structure of warm periods. the chronologic model suggests a major role especially of the 100 kyrs-period oscillations. in particular, (absolute or relative) eccentricity maxima correlate 139 interglacials at the empt in southern italy well with the first (sandwich) structure. an in-depth statistical approach would permit to test relationships between orbital and vegetation phenomena but also to better understand how astronomical factors modulate vegetation changes during interglacials and warm phases (tzedakis, 2012a, b). the present study also fits the issue concerning the extent of the impact of the empt on terrestrial ecosystems. finally the high-resolution record of one of the investigated interglacials, i.e. mis 19, represents a par 140 toti f. fig. 7 selected samples of the warm periods of the montalbano jonico pollen record marked with colours from the cluster analysis -, “warm” pollen zones and oxygen isotopic curve (brilli et al., 2000; ciaranfi et al., 2010; marino et al., 2015). ticularly appreciable datum as it is now considered one of the “best analogues” of the present interglacial (berger et al., 2012; tzedakis at al., 2012a). acknowledgements this research has been financially supported by the università degli studi di firenze (fondi di ateneo, a. bertini 2011-2013) and a phd fellowship. the author is deeply grateful to adele bertini and antonella buccianti (università degli studi di firenze) for the many constructive advices. the author wish to thank luigi forte, neri ciaranfi, angela girone, patrizia maiorano and maria marino (università degli studi di bari, aldo moro). a thanks goes to elda russo ermolli and an anonymous reviewer for the thoughtful comments on the previous version of the manuscript. references aitchison j. 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(1995) interglacial vegetation succession: a view from southern europe. quaternary science reviews, 14, 967-982. tzedakis p.c. (2007) seven ambiguities in the mediterranean palaeoenvironmental narrative. quaternary science reviews, 26, 2042-2066 tzedakis p.c., wolff e.w., skinner l.c., brovkin v., hodell d.a., mcmanus j.f., raynaud d. (2012a) can we predict the duration of an interglacial? climate of the past, 8, 1473-1485. tzedakis p.c., channell j.e.t., hodell d.a., kleiven h.f., skinner l.c. (2012b) determining the natural length of the current interglacial. nature geoscience, 5, 138-141. watts, w.a. (1988) europe. in: huntley b., webb iii t. (eds), handbook of vegetation science 7. vegetation history. kluwer, dordrecht, pp. 155-192. 143 interglacials at the empt in southern italy imp.napoleone ccaalliibbrraattiioonn ooff tthhee uuppppeerr vvaallddaarrnnoo bbaassiinn ttoo tthhee pplliioo--pplleeiissttoocceennee ffoorr ccoorrrreellaattiinngg tthhee aappeennnniinnee ccoonnttiinneennttaall sseeqquueenncceess ggiioovvaannnnii nnaappoolleeoonnee11,,22,, aannddrreeaa aallbbiiaanneellllii11,, aauugguussttoo aazzzzaarroollii11,,22,, aaddeellee bbeerrttiinnii11,,22,, mmaauurriizziioo mmaaggii11,, mmeennoottttii mmaazzzziinnii22 1dipartimento di scienze della terra, università di firenze, via la pira, 4 i 50121 2museo di storia naturale, sezione di geologia e paleontologia, università di firenze, via la pira, 4 i 50121 e-mail: napo19@unifi.it albix@geo.unifi.it abertini@geo.unifi.it menotti@unifi.it abstract the upper valdarno continental sequence is formed by 500 m thick sediments calibrated to gauss and matuyama chrons, for nearly 2.5 my history. continuity in lacustrine and fluviatile deposition is interrupted by two major pulses of the apennine uplift. one is dated to the boundary of the gauss/matuyama chrons at 2.58 ma and lasts until 2.1 ma, the other from shortly after the olduvai chron at 1.77 ma until 1.05 ma (jaramillo), or 0.78 ma (brunhes). such interruptions are recorded differently. the former by a condensed sequence containing two events of the magnetic polarity, the g/m boundary and the short normal chron reunion within the early matuyama, while the second missed any record. the condensed sequence is of wind-blown sands, with scanty levels of fine silt, used also for pollen analyses. the deposition intervals, now dated in the lacustrine sequences, are similarly long. in the first basin filling, from mammoth at 3.3 ma, the lake deposits of uniform silty clays, the meleto clays, began at nearly 3.15 ma, from shortly before kaena through the latest gauss. this time span was separately measured by spectral content of the magnetic signal to last 400 ky; there, cyclostratigraphy enhanced periods of various lengths accounting for either different rates of deposition through the time series or the occurrence of a bimodal cyclicity at 2.85 ma. at this time, the pollen record started moving towards a reduction of species of the subtropical forest and an increase of the altitudinal coniferous vegetation; an oscillating pattern from open to forest vegetation took place in the early matuyama. in the second lacustrine cycle the record is less continuous, and the highest percentage of herbs is reached at nearly the p/p boundary. key villafranchian faunas, from triversa or villafranca d’asti sequence of north-western italy to pirro faunas of south-eastern italy, were grouped in the biochronologic sequence of different faunal units, and are now correlated with the upper valdarno chronostratigraphic framework. after the early villafranchian, the montopoli fauna, the only one with a date (2.58 ma) before the calibration of the upper valdarno, marked the major change with the preceding fauna of triversa, leading to the middle villafranchian. the other faunas formed the late villafranchian, from olivola of north-western apennines to tasso of upper valdarno and farneta in central italy to pirro, which were little affected by the global changes occurred at the p/p boundary. after the villafranchian age, the new fauna starts to build the asset of the present day distribution at the end of the matuyama, and possibly at the boundary with the jaramillo chron, as recorded also in the upper valdarno. devoid of a direct calibration, these faunas containing the mammal neogene (mn) age units mn16a mn16b and mn17 of western europe faunal distribution, had always been very difficult to correlate with biostratigraphy, and even more with the geomagnetic polarity time scale gpts. they are now placed relative to the upper valdarno magnetochronology, from mammoth to jaramillo. the high resolution of the upper valdarno is viable for finer enhancements in the apennine sequences explored by direct magnetostratigraphies. these will permit the dating of their complete faunal sequences and correlate them with the european late-neogene mammal faunas. riassunto la datazione dei depositi continenali del valdarno superiore è stata effettuata per una estensione di ca. 2.5 milioni di anni (ma), ricostruendo dai vari affioramenti, lungo 30 km di estensione del bacino, la successione sedimentaria. su entrambi i fianchi della valle, essa è stata testimone di diverse quantità di apporto e di erosione, nel corso della sua storia intervallata da due fasi tettoniche che ne hanno segnato l'assetto. la più intensa è datata con inizio in prossimità del limite tra i magnetocroni a polarità normale gauss (c2an.1n) e matuyama (c1r.3r) inversa, a 2.58 ma. essa è responsabile della netta dislocazione del fianco orientale del bacino che ha depresso il bordo delle argille lacustri (a. di meleto) con un'inclinazione a ne di oltre 30°. la seconda crisi tettonica segna la fine della seconda fase deposizionale, con il riempimento del bacino in corrispondenza della crisi climatica globale alla fine del pliocene che segna il limite con il pleistocene. gli ultimi depositi di questo ciclo sono datati fino a dopo il debutto della nuova fase, cioè ad un'età appena più recente del limite plio-pleistocene, superando di poco la fine del crono olduvai (c2n) che è alla data di 1.77 ma. la terza fase si apre senza apparenti discordanze nel versante a destra dell’arno e con una di valore modesto, nel versante sinistro. molto più consistente è invece il salto cronologico: esso coinvolge quasi tutta la porzione post-olduvai del matuyama (c1r.2r), per almeno 650 mila anni (ka), prima della nuova fase, segnata con una breve alternanza di magnetizzazione inversa e normale. nella scala gpts dei tempi magnetici la prima polarità normale dopo l'olduvai si riscontra alla data di 1.05 ma, jaramillo (c1r.1n), e la seconda, brunhes (c1n), alla data di 0.78 ma alla quale è calibrato il limite del pleistocene medio. a questi punti fermi magnetocronologici si aggiungono quelli forniti dagli eventi sedimentari più rimarchevoli, che accompagnano i cambiamenti protrattisi per durate notevoli; anche queste durate, segnate dallo scorrere di una deposizione con velocità non sempre costante, sono state misurate. i primi depositi sono i conglomerati di base (ciottolami di spedalino), che cominciano alla data di oltre 3.3 ma nel mammoth (c2an.2r) e poggiano sul basamento oligo-miocenico delle arenarie del macigno. la deposizione assume quindi un regime continuo in acque molto basse, con il breve episodio di accumulo palustre di ligniti, che lateralmente al piccolo lago poggiano direttamente sul basamento. il livello più basso di ligniti è compreso tra la fine del breve crono a polarità normale (c2an.2n) prima del kaena (c2an.1r) e l’inizio di quest’ultimo, cioè in un breve intervallo valutabile in qualche decina di ka a cavallo del limite a 3.11 ma. a questa data è ricondotta l’età della prima fauna a vertebrati, che aveva fornito la datazione precedente dei depositi palustri all’inizio del villafranchiano. quindi il depocentro si approfondisce e si depositano argille sabbiose e limi (argille di meleto) la cui sedimentazione continua si estende per tutto il gauss terminale (3.04÷2.58 ma), senza però raggiungerne il limite, perché interrotta dal riempimento sabbioso del lago. la ricostruzione della serie deposta durante il gauss (senza nessun reperto fossilifero) è stata effettuata attraverso l’analisi spettrale della oscillazione continua del segnale magnetico. essa ha fornito la ciclostratigrafia della serie fino ai 60 ka prima del limite, cioè fino alla data di 2.64 ma, dopo dei quali si depositano rapidamente le sabbie di riempimento del lago (sabbie di s. donato). una foresta subtropicale di clima caldo umido è presente durante la formazione della lignite in un ambiente di palude arborata e prosegue per buona parte della successiva prevalente deposizione lacustre. il progressivo fenomeno di raffrescamento, segnalato dai “record marini” come più evidente a partire da circa 2.77 ma, determina una progressiva riduzione degli elementi più termofili e il contemporaneo aumento delle conifere di altitudine tipiche oggi delle foreste boreali. non si registrano variazioni significative nei valori delil quaternario italian journal of quaternary sciences 1166(1bis), 2003, 131-166 132 g. napoleone et al. 11.. iinnttrroodduuccttiioonn the continental deposits of the upper valdarno represent a fundamental key for timing the major apennine uplift during pliocene and pleistocene (fig. 1). also their fossil record of mammals became famous in the late seventeen hundreds and was studied in the early eighteen hundreds with a decisive contribution to the development of palaeontology. the first represented fossil was the proboscidean jaw reproduced by nesti in 1808, followed by rich collections. during the last 50 years the museum collections were reconsidered, and thence arranged in the villafranchian biochronological sequence (azzaroli, 1977a) which was further enriched l’umidità, i quali invece risulteranno fortemente alterati in seguito all’instaurarsi dei cicli glaciali/interglaciali a partire dall’inizio del matuyama. alle sabbie di san donato seguono in discordanza le sabbie della fase di erosione e inclinazione degli strati verso ne (rena bianca): nei pochi livelli limosi misurati, esse hanno fornito tratti discontinui di una polarità normale alla base, seguita da una inversa, ed interpretati come il limite gauss-matuyama, fino al breve crono con polarità normale, reunion (2.15 ma), e l’inizio di una nuova parte del matuyama c2r.1r, con i limi della nuova fase fluvio-lacustre della serie del ciclo di montevarchi (limi di terranuova). questa serie è in continuità sulle sabbie della rena bianca, nella parte più occidentale in sinistra d'arno; nella serie del depocentro affiorante in destra d'arno il contatto non è stato mai rinvenuto. qui, il nuovo livello argilloso affiora nel letto dell’arno e la sua età è prossima a 2.1 ma; il primo livello fossilifero, invece, è alla data di 1.99 ma. esso inaugura la nuova fauna del villafranchiano superiore, che nella sezione di faella si rinviene con una distribuzione stratigrafica di 220 ka ed è parimenti datata con la correlazione magnetostratigrafica poco dopo l’olduvai. infatti, nella sezione composita di faella e galleria tasso, la serie procede con l’inizio del magnetocrono a polarità normale olduvai a 1.95 ma. la sua prima porzione arriva a 1.815 ma, seguita da un breve tratto a polarità inversa fino a 1.785 ma ed un nuovo normale fino a 1.77 ma, secondo la calibrazione effettuata nello stratotipo della vrica. in quest'ultimo, il limite p/p è definito a 1.796 ma, entro la breve inversione al tetto dell’olduvai. in ca. 300 ka intorno al limite p/p è racchiuso tutto l’arco del villafranchiano superiore presente nel valdarno superiore fino all’unità faunistica tasso, che però costituisce la grande maggioranza delle collezioni del museo di firenze. gli elementi di una foresta subtropicale-temperato calda progressivamente sempre più impoverita nei suoi elementi più termofili si alternano a quelli erbacei tipici di una vegetazione aperta nella quale trovano spazio anche numerosi elementi steppici. nei sedimenti della rena bianca, il passaggio gauss-matuyama, è marcato dalla prima registrazione testimoniante l’espansione della vegetazione steppica con artemisia che raggiunge per la prima volta valori dell’ordine di oltre il 20%. con tali punti di controllo, datati con l’accuratezza di 10 ka, entro la quale si ritiene compresa la durata di transizione da una polarità all’altra, anche le date di tutti gli eventi faunistici, pollinici e sedimentari sono fissate lungo la serie, con accuratezze cioè di qualche ka. in particolare, per quelli del secondo ciclo sedimentario di montevarchi che risultano continui per la durata complessiva da ca. 2.05 ma a ca. 1.75 ma, gli eventi faunistici sono scanditi entro 2 ka e quelli vegetazionali correlati con le alternanze delle ciclicità astronomiche di milankovitch misurate dalla distribuzione spettrale del segnale magnetico. gli eventi faunistici sono quelli classici del villafranchiano superiore successivi alla fauna di olivola della toscana settentrionale. sono costellati da depositi fossiliferi fra i più cospicui, come la fauna del tasso della fine dell’800 e quella di poggio rosso della fine del 900, nonchè dai reperti isolati che sono stati riposizionati nella serie di montevarchi, come il rinoceronte di nesti del 1811 e l’elefante di azzaroli del 1953. ora, queste collezioni del museo di firenze sono datate insieme con la calibrazione del limite p/p rapportato alla stratotipo della vrica. quindi, così come alla vrica, il limite p/p è marcato dall’instaurarsi di una fase glaciale che si traduce in un’espansione della vegetazione erbacea, e tale fase è preceduta da una lunga fase calda ed umida. i successivi cicli glaciali-interglaciali si differenziano ulteriormente da quelli pliocenici per una notevole riduzione nella diversità floristica determinata dalla progressiva scomparsa nel corso del pleistocene di numerosi taxa (ad esempio taxodiaceae, cathaya e tsuga). le sabbie di oreno sovrastanti le argille di ascione chiudono il ciclo di montevarchi, e con esso termina il villafranchiano nel bacino del valdarno superiore. la sedimentazione riprende dopo una interruzione non valutabile, sul versante destro dell'arno, in mancanza di una serie magnetostratigrafica: nella parte se del bacino, presso lévane (cava specchiano), pochi livelli limosi nei ciottolami di laterina e nelle sabbie di lévane hanno fornito una polarità inversa attribuita al matuyama superiore. sul versante sinistro, nella zona a sw presso bucine (cava gori), i conglomerati sono a polarità inversa e i limi e le argille soprastanti a polarità normale. la ricca fauna di bucine, rinvenuta negli strati sabbioso-ghiaiosi a copertura degli ultimi depositi, nettamente post-villafranchiana, era anzi rapportata ai tempi del pleistocene medio terminale sulla base delle evidenze archeo-antropologiche di reperti litici. sia che il salto di polarità corrisponda ai tempi magnetici del crono jaramillo che a quelli del brunhes, rimane l'importante indicazione che il tempo trascorso dopo gli ultimi depositi della serie di montevarchi è vicino a/o raggiunge 1 ma, che è pertanto il salto dalla fauna del tasso a quella di bucine. da tale quadro cronologico emergono le condizioni per calibrare gli eventi faunistici e floristici dei bacini intermontani dell’appennino, correlandoli con quelli del valdarno superiore. il prototipo è dato dal bacino tiberino. il “record” pollinico della formazione di fosso bianco è stato calibrato direttamente con la magnetostratigrafia, per 600 ka, durante il gauss terminale ed il matuyama fino a tutto il reunion. l’unica indicazione cronologica è data dalla ridotta associazione faunistica di todi, rinvenuta a cava toppetti nella sovrastante formazione di ponte naia ed attribuita al villafranchiano medio, tra le età dell'unità faunistica di montopoli (calibrata a 2.58 ma) e quella di olivola (ora datata a ca. 2.1 ma): essa risulta perciò entro confini molto ristretti, intorno ad una età prima di olivola, ma certamente non prima di 2.15 ma, essendo posteriore al reunion. per gli altri bacini, nonostante la mancanza di controlli magnetostratigrafici diretti, le età che erano state fissate con i criteri biocronologici vengono ora circoscritte intorno a date che le hanno talvolta spostate notevolmente. la stessa durata del villafranchiano, ritenuta nel valdarno superiore estendersi dal pliocene medio a circa la fine del pleistocene inferiore, è stata accorciata all’età biostratigrafica di poche decine di ka dopo l’inizio del pleistocene. nella calibrazione alla scala gpts questo comincia nell’olduvai terminale, a circa 1.8 ma e l’età del villafranchiano arriva nel valdarno superiore a ca. 1.75 ma, cioè con una riduzione di 600-700 ka rispetto a quanto implicato dalle precedenti correlazioni indirette. con la completezza del quadro magnetocronologico del valdarno superiore possono essere correlate le faune principali dei bacini appenninici, e gli eventi sedimentari e floristici rinvenuti nei due versanti della catena. in particolare, viene riportata la nuova interpretazione della successione stratigrafica dei depositi faunistici, a partire da quello di villafranca d’asti, come rieferimento per il villafranchiano, che risulta coevo con quello di castelnuovo dei sabbioni. seguono le età di montopoli (già nota, a 2.58 ma) e di olivola ora interpretata a 2.1 ma, mentre quelle di tasso e farneta sono molto prossime fra loro ed entrambe appena dopo il limite pliopleistocene; quella di pirro alquanto indefinita. il passaggio alla fase nuova che prelude alla fauna attuale è marcato al crono jaramillo, 1.05 ma. key words: magnetochronology, upper valdarno basin, villafranchian faunas, pliocene correlations, pleistocene boundary, vegetational changes, climate changes. parole chiave: magnetocronologia, valdarno superiore, faune villafranchiane, pliocene, pleistocene, variazioni climatiche. by various details (azzaroli, 1977b; 1983; 1992; 1995; 1998; 2001; azzaroli et al. 1988; 1997), until magnetostratigraphy provided the dates for the whole record beginning from nearly 3.1 ma (fig. 2). in a framework related to the geomagnetic polarity time scale (gpts), the new historical reconstruction of the upper valdarno faunal sequence is correlated with great confidence with the sedimentologic and climatic ones. magnetic stratigraphy has in fact demonstrated the onset of the continental deposition at 3.3 ma and of the lacustrine facies at 3.1 ma, when the first faunal sequence was also recorded (albianelli et al., 1997). its end was close to the gauss/matuyama boundary. a second lake developed at 2.1 ma and a new fossil record has been dated since 1.99 ma (cioppi & napoleone, 2001, napoleone et al., 2001c, albianelli et al., 2002a). in the mean time, the sedimentary features showed a marked change in the 450 ky time series of the first lake with a gradual increase of the deposition rate by more than 60% from the middle to the end of the late gauss chron (albianelli et al., 1999, napoleone & albianelli, 2002). it was recorded by the magnetic signal as mainly related to milankovitch climatic changes that were also recorded by the pollen distribution (bertini, 1994; bertini & roiron, 1997). two results emerged from these studies. one was to date the turnover of the milankovitch precessional signal towards the obliquity one at 2.85 ma, when also the pollen of warm-temperate forest began to change towards a cooler vegetation and later alternate with the warmer one at nearly the 133calibration of the upper val d’arno basin ... gauss/matuyama boundary. the other one was to find the pliocene/pleistocene boundary with the same features as in the stratotype (van couvering, 1997), and to record the acme of the pollen concentration up to 89% of steppe herbs in proximity of that boundary. the present contribution summarizes these results and the ones from additional studies not reported in specific accounts, with the aim of developing the comprehensive history of the basin directly calibrated to the numerical dates of the gpts. we briefly review the classical faunas of the upper valdarno as illustrated by azzaroli et al. (1988), together with the faella small collection now revised in its composition because of new acquisitions in the inventory of specimens from different levels of the faella clay pit. other specimens were also considered from the finds accurately reported in the automated catalogue of the museum of firenze (cioppi et al., 1996). accuracy on their stratigraphic position reflects on their datings, with a confidence of 2 to 15 ky, that build the base for correlation of most apennine faunas which were until now approximately placed in the biostratigraphic chronology, and fairly incorrectly related to the gpts. 22.. bbiioocchhrroonnoollooggiicc hhiissttoorryy ooff tthhee uuppppeerr vvaallddaarrnnoo sseeqquueennccee the early geologic reconstructions were made for the italian peninsula, at the same time when also the upper valdarno chronostratigraphy was established. its continental deposits were classified in the general asset of the marine sequences, with the pliocene clay (blue clay formation) overlain by the pleistocene sand (cocchi, 1856; pareto, 1865). both successions were believed to be of equivalent geochronologic resolution, and biochronology of the mammal age classification was associated with the biostratigraphic classification. the villafranchian defined by pareto (1865) for the triversa vertebrate fauna of villafranca d'asti in piemonte (north-western italy) was later extended to the sequences of peninsular italy, and its onset related to the early pliocene (azzaroli, 1977a), in its twofold definition before a third stage was recently introduced for the latest pliocene. the mid villafranchian is represented by the montopoli fauna, collected in the lower valdarno basin, and related to the late pliocene, while the olivola fauna of late villafranchian collected in northwestern toscana was assumed to mark the beginning of the pleistocene. magnetochronology has now figure 1 general tectonic setting of the intramontane basins along the northern apennine belt (modified, after martini and sagri, 1993). the upper and lower valdarno, south and west from florence, respectively, and valtiberina farther south from upper valdarno are the only ones here taken into account for their direct calibration by magnetic stratigraphy, but their features are typical throughout the italian peninsula. 134 fixed new dates for the pliocene and pleistocene, so that the previous correlation used for assigning an age to the major turnovers in the terrestrial fauna is recognized to diverge from the ones of the marine record. the main difference is at the pliocene/pleistocene boundary, which did not mark any vertebrate diversification, as pointed out from the following facts (to be discussed in the chapter on calibrations). the earliest turnover of vertebrate associations (azzaroli, 1983) took place at 2.58 ma, the boundary between the gauss (c2an.1n) and matuyama (c1r.3r) chrons, which also calibrates to the gpts the boundary of the middle to late pliocene (berggren et al., 1995). the next one marked the extinction of the main taxa which are no longer represented in the presentday faunal associations and was dated at the jaramillo chron, approximately 1 ma (azzaroli, 1995). the mid pleistocene boundary was calibrated to the following chron of brunhes, while the onset of the quaternary recorded only the so-called “wolfevent” with the arrival of a new canis (xenocyon) overlapping the previous mid villafranchian one (torre et al., 2001). this lack of major events was also one of the reasons why the pleistocene boundary had a late recognition (pasini & colalongo, 1997) and correlation with it of the italian mammal fauna was actually made through the himalayan sequence (azzaroli et al., 1997), calibrated to the pliocene and pleistocene by its magnetostratigraphy (azzaroli & napoleone, 1981). with calibration of the stratotype to the gpts at the date of 1.796 ma, also the upper valdarno series is defined by the same dates, including the boundary at the pliocene/pleistocene, and the various ages before and after it which become actually correlated at the highest resolution with their faunal events. the main aspects of the upper valdarno faunal record are recalled here, as they represent most reference events for the villafranchian vertebrates of the italian peninsula and will put the benchmarks for magnetochronologic calibration of several of them. the first fauna of castelnuovo dei sabbioni (early villa-franchian) is separated from the next one of the montevarchi sedimentary cycle (late villafranchian) by the wind blown and unfossiliferous sands of rena bianca. its intermediate position, covering the middle villafranchian age actually missing in the upper valdarno, is represented by a single fossil which has been hitherto allegedly found, a partial skeleton of a mastodont described and partly figured by nesti in 1826, and now referred to anancus arvernensis by azzaroli. the fossil was restored and is exhibited in the museum of firenze; its provenance was not reported by nesti and the position in the rena bianca is here only inferred. g. napoleone et al. figure 2 magnetostratigraphic asset of the upper valdarno sedimentary sequence used for dating the villafranchian faunas and implemented by the present results. the basic figure was after albianelli (1995), and first used in cioppi and napoleone (2001). an important change is now introduced, after recognizing the unconformity between rena bianca and san donato sand units, so that they are split in two zones belonging to the montevarchi cycle and to the castelnuovo cycle, respectively. the san donato sand represents therefore a short time span, and rena bianca a condensed sequence to which the valtiberina profile at todi provides a full extent for correlation. the montevarchi sequence is synthesized from various profiles; the filling sediments are not reported herein. 135 22..11 tthhee ccaasstteellnnuuoovvoo ddeeii ssaabbbbiioonnii llooccaalliittyy the mining of the lignite-bearing levels of the basal unit yielded few fossil specimens kept in the university museum of firenze. the small collection assembled as the castelnuovo dei sabbioni fauna actually came from various sites of the old small mines (gaville, tegolaio, etc.), distributed in the area around the small town of castelnuovo dei sabbioni. the last and largest one at santa barbara provided extended outcrops used for surveying various sedimentary aspects, but its industrialized exploitement did not allow any fossil recovery (fig. 3). the fauna is characterized by the mastodonts zygolophodon borsoni, anancus arvernensis, and by ursus minimus, the perissodactyl tapirus arvernensis, the turtle mauremys etrusca, the fish tinca sp. it has been correlated with the triversa fauna occurring at villafranca d'asti in piemonte and is characterized by the same faunal elements (azzaroli, 1977a). as the triversa assemblage was taken by pareto (1865) to represent the villafranchian terranes (see the discussion reported in azzaroli, 2001), the triversa locality was assigned as the base of the villafranchian stage, and the castelnuovo locality was accordingly positioned at the same time level. the rough chronostratigraphy derived from broad correlations with the marine sequences gave an age of pliocene, actually corresponding to a lower piacenzian as defined by pareto (1865). therefore, the castelnuovo fauna represents the earliest mammal assemblage from the apennine intramontane basins developed with the plio-pleistocene uplifting of the chain. the present date, produced by its magnetostratigraphic determination (see in chapter 5), is calibrated to the gpts and will be used (in chapter 6) to date more accurately the reference assemblage of triversa by a correlation better defined. calibration of the upper val d’arno basin ... figure 4 the earliest illustration of a fossil specimen from the upper valdarno old collections (after nesti, 1808, reproduced in azzaroli et al., 1992). this proboscidean was tentatively attributed by azzaroli to anancus arvernensis. figure 3 the outcrop of the meleto clay in the santa barbara pit, opened for the exploitement of the lignite seam. in the foreground, the lignite-bearing level has already been removed, and the paleomagnetic survey has been carried out up to the top. the sampling for palynology was conducted earlier, in the profile on the left side of the section, 1 km away. 136 22..22 llooccaall ffaauunnaass iinn tthhee mmoonntteevvaarrcchhii sseeqquueennccee in this complex, forming the second depositional cycle, the bulk of the upper valdarno fauna stored in the palaeontological museum of firenze has been collected since early eighteen hundreds, and a large collection is also stored in the famous museum of montevarchi, the town from which the succession is named. the first catalogue of the upper valdarno fossils in the museum of firenze was assembled by filippo nesti in 1845, and contained the list of 356 specimens (azzaroli et al., 1992). some of them are in the exhibition, representing the best pieces for the study collection, and were studied in detail to create the base for the developments in palaeontology. the earliest description, dating from 1808, is a toothless jaw of a then unnamed proboscidean; it belongs to a mastodont, likely from the older lake of castelnuovo dei sabbioni and tentatively assigned to anancus arvernensis (fig. 4). a second fossil was the rhinoceros described by nesti in 1811 (a pelvis and the four limbs), named rhinoceros etruscus, and now stephanorhinus etruscus. the detailed description of the site location has now been reconsidered for dating the embedding sequence, and the level of provenance recognized in the sequence of poggio di monte al pero, which is the hill peak by the side of matassino, another important fossil site. these localities are both dated with high resolution by magnetostratigraphy of their sequences, as reported in chapter 5. the oldest fossils collected so far in the montevarchi sequence are an antler of a juvenile cervid, pseudodama nestii (fig. 5) acquired in the catalogue on april 1999, and a tibia of the equus stehlini acquired in the catalogue on january 2000, with specimens of a few more species. they all come from the lowermost 10÷15 m of the faella section, 2 km away from that of matassino, on the right (eastern) bank of the arno river (see on map of fig. 8). as discussed in the next sections, the faella outcrop represented the key for new insights into the biochronologic history of the upper valdarno, because the whole fauna collected in two centuries from this area and resumed from the catalogue was calibrated, thus becoming the reference for the equivalent faunal collections. in fact it spans all through the montevarchi succession from which most of the fossil sites were retrieved. the species list of the faella small collection of 29 specimens includes pachycrocuta brevirostris, leptobos etruscus, leptobos vallisarni, sus strozzii, eucladoceros dicranios, canis arnensis, ursus etruscus, archidiskodon meridionalis, pseudodama nestii, equus stehlini. they are now dated in stratigraphical sequence, as will be discussed in the magnetochronologic section, even if a provenance of the specimens in the old collections was not reported (napoleone & azzaroli, 2002). cocchi (1867) made an important recovery at the same level as the base of the faella section, just across the faella creek and at the foot of the monte al pero hill, with two additional genera: megantereon and rhinoceros (now stephanorhinus). the matassino hill is the northern flank of monte al pero, and culminates with the peak of poggio rosso. at its base, the matassino site was the first rich assemblage recovered in the uv as one single deposit (azzaroli, 1967), in a channelled sand pocket, with two young male and female elephants, the latter shown in figure 6. it was dated to the late villafranchian and represented until three years ago the oldest faunal assemblage in the montevarchi sequence, for which a close affinity with the olivola fauna was recognized (azzaroli, 1977a) and an age of earliest pleistocene was since established. the matassino local mammal fauna (lmf) is assembled in the catalogue list from 8 sites around the mentioned deposit and contains most of the species of the faella previous list, totalling 12, including the canis arnensis described by torre (1967). in the same sequence of the matassino locality, some 30 m higher up, a very rich fauna was discovered in 1995 (mazzini m. et al., 2000), the poggio rosso fauna, and is under preparation. a list of the specimens exhibited in the museum during 1997÷2002 included 13 species, archidiskodon meridionalis, equus stenonis, equus stehlini, stephanorhinus etruscus, leptobos etruscus, eucladoceros dicranios, pseudodama nestii, sus strozzii, pachycrocuta brevirostris, canis etruscus, canis arnensis, ursus etruscus, castor plicidens. the species are now 19 out of more than one thousand specimens restored and preliminarily examined; the complete list of more than 15 hundred specimens is not yet fully included in the automated catalogue. the fauna lies in a channelled sand pocket and was washed in by a stream during a flood. although the association has still to be defined, all groups being under study, there appear to be present the most characteristic elements that had been attributed for their analogies to the olivola faunal unit (reported later, in chapter 6), with the exclusion of the species endemic to that site and with the addition of equus stehlini, canis arnensis, castor plicidens and hystrix etrusca. the latter species was described from other sites of the basin by bosco in late eighteen hundreds (quoted in azzaroli, 1998). owing to transport by a stream the elephant is represented by few g. napoleone et al. figure 5 one of the most recent acquisitions (april 1999) of the upper valdarno fossils made by the natural history museum of firenze, the cervid antler of a juvenile specimen at the base of the faella clay pit, few meters by the side of the faella creek. in january 2000, a few meters underneath, the oldest fossils of the late villafranchian dated 1.99 ma have been found. bones of the hand. two complete skeletons of the elephant archidiskodon meridionalis m. were collected by azzaroli in the montevarchi territory, on the left bank of the arno. the one collected in 1949 is stored in the montevarchi museum, and a male skeleton was collected in 1953 on a hilltop at the borro quercio creek. the find of 1949 was recovered not far and at a level slightly higher than that of the other one, and determined as a young female individual of elephas meridionalis nesti (azzaroli, 1952). the find of 1953, stored in the museum of firenze, has been reappraised (azzaroli & napoleone, in ms) to report on its preliminary determinations and on accurate chronology of its level bed (fig. 7). a fairly rich fauna was collected in recent years near casa frata, not far nw of the town of terranuova bracciolini (borselli et al., 1980; de giuli & masini, 1986), and is still under study. it includes canis etruscus, canis falconeri (?), ursus etruscus, martes sp., pachycrocuta brevirostris, lynx cf. issiodorensis, acynonyx pardinensis, homotherium crenatidens, eucladoceros sp., pseudodama sp., equus stehlini, stephanorhinus etruscus and the limbs of a mediumsized, heavily built bovid, which has not yet been detected in other sites of the upper valdarno. the sequence containing the two major deposits of the casa frata assemblage is not well exposed and has not been studied for palaeomagnetism. from the vicinity of the area labeled in the museum catalogue as il tasso come: lepus etruscus, castor plicidens, mimomys savini, canis etruscus, canis arnensis, canis falconeri (now canis (xenocyon) ex gr. falconeri, rook, 1994), ursus etruscus, martes sp., pannonictis nestii, pachycrocuta brevirostris, lynx issiodorensis, panthera toscana, homotherium crenatidens, megantereon cultridens, stephanorhinus etruscus, equus stehlini, sus strozzii, pseudodama nestii, eucladoceros dicranios, leptobos vallisarni, archidiskodon meridionalis. the occurrence of equus stenonis and leptobos etruscus is doubtful, that of the hippopotamus antiquus included in the catalogue as belonging to this group will be discussed at the end of this chapter. several more localities with minor finds and/or of undetermined positions are classified in the catalogue, but their variability is not recognizable from the above mentioned localities already ordered in stratigraphic succession, as dated later by their magnetochronology. a large tusk of an elephant was collected by azzaroli and de giuli in 1975, west of montevarchi and near km 41 of the road from siena, at an altitude of 205÷210 m. it is decidedly larger than the tusks of the borro quercio elephant and other tusks from the upper valdarno and nearly equals in size to the specimens found near the farneta abbey in eastern toscana, to be discussed in the stratigraphical reconstructions of chapter 6. 22..33 aaddddiittiioonnaall ffaauunnaass aafftteerr tthhee pplleeiissttoocceennee bboouunnddaarryy the basin fill is recorded in a short succession overlying the eartliest pleistocene sand. the one exposed on the right-hand bank of the arno did not yield any fossil remains but the frontal skull of a bovid; on the lefthand side, in contrast, a rich assemblage was collected and labeled as the bucine local fauna, even if randomly found on the surface, in the area around pogi, south of the small town of bucine. these sediments extend in a flat area from bucine to ambra, beyond the southern margin of the valdarno basin at an altitude of 220÷240 m, unconformably sitting on the previous unit. in the late eighteen hundreds, during the reconstruction of the railroad from firenze to roma, a set of tunnels were opened near bucine at an altitude of 205÷207 m. in one of these, forsyth major collected a set of teeth of the reported late middle pleistocene equus süssenbornensis von reichenau (azzaroli, 1984). higher up in this area, near the village of pogi, a small fauna was collected in the 1960s and stored in the museum of firenze: 137calibration of the upper val d’arno basin ... figure 6 a specimen of the first fossil assemblege recovered at matassino by the staff of the museum of firenze, in a channelled deposit of sand and fine gravel interlayered in the terranuova silt level which is now dated as just preceding the onset of the olduvai chron at 1.95 ma (albianelli & napoleone, 2002, unpublished data). figure 7 the largest specimen in the exhibition of the natural history museum of firenze, collected in 1953 near montevarchi and now dated in the upper olduvai, at nearly 1. 85 ma (azzaroli & napoleone, 2002). mammuthus primigenius, a lower molar; equus ferus, a left metacarpal; dama dama, a left metatarsal; cervus elaphus, a right antler; stephanorhinus hemitoechus, a male skull; grus cf. cinerea, a partial humerus, tibio-tarsus. it was assigned an age of late, but not latest pleistocene. three upper and two lower molars referable to equus ferus (named equus caballus by azzaroli, 1984), and a left horncore of bison schoetensacki from the higher levels of the eastern margin of the basin were also described by the same author and were referred to the late pleistocene. the assemblage kept in the palaeontological collection of the montevarchi museum and of the high school of bucine comes from 11 collecting localities listed by mazza (1997), and used to reconstruct the taphonomy of their occurrence: elephas (palaeoloxodon) antiquus, mammuthus primigenius, stephanorhinus sp., equus gr. bressanus-süssenbornensis, sus scrofa, bos primigenius, bison priscus, cervus elaphus, dama dama, megaloceros sp., capreolus capreolus, ursus arctos, canis lupus, crocuta crocuta, castor fiber. the biochronologic dating of this fauna, although decidedly more derived than the villafranchian ones, is not sufficient to resolve its age in some detail. the age of late middle pleistocene (latest galerian ?) was arbitrarily assigned, lacking any stratigraphic correlation, as will be shown by its calibration. the efforts of cocchi (1856) and pareto (1865) to correlate continental sequences with the marine ones were not improved by the biochronologic attempts for dating deposition gaps of unknown duration. in the upper valdarno filling, this has been a major problem until magnetostratigraphy provided the numerical dating of their time intervals (napoleone et al., 2001c). a 30 m thick sequence, in the upper silt and clay underlying the final thin bed of sand, was surveyed for magnetics in a gravel and sand pit, in the vicinity of bucine. also in a shorter section of a similar pit, ca. 1 km away, the same sequence was sampled after an elephant tusk was reported by one of us (m. mazzini) on the 21st of october 2001, in the yellowish lenticular fluvial deposits. several remains of elephas antiquus were recovered on the 26th, 27th, and 29th of october, and the specimen is labeled in the inventory of the museum as igf 8215v. the fossil level was above the gravel bank and a less than 10 m section was sampled for magnetostratigraphy, including two clay and silt lenticular levels in the gravel bank. the hippopotamus of the upper valdarno, descibed by nesti and grouped with the large assemblage of specimens of the tasso faunal unit, devoid of a position within the montevarchi sequence, raises a problem. the fossils, which slightly differ from the living species, are plentiful. nesti gave no details on their locality, and no fossils of this species were collected in recent years, either in the upper valdarno or in younger deposits of the farneta area of val di chiana and the mugello basin, north of firenze (reported in chapter 6). this leads us to suppose that the hippopotami are of a younger age than the main upper valdarno fauna. the remains of a similar hippopotamus were collected in recent years farther east, at the boundary between umbria and marche districts of central italy, in the colfiorito basin, associated with other remains of postvillafranchian fossils (borselli et al., 1988). the upper valdarno fauna, owing to its richness and recent acquisitions, has not yet been studied with the detail it deserves. 33.. tteeccttoonniicc aanndd sseeddiimmeennttaarryy eevvoolluuttiioonn ooff tthhee bbaassiinn the arno river makes its 240 km path running from the casentino valley in east toscana, first south towards arezzo, and before reaching the town it turns west and then north to firenze, across the upper valdarno basin (fig. 1). after the firenze basin, it continues west cutting a series of hills and, in the lower valdarno basin, the shallow marine deposits of miocene and early pliocene. sometimes its early and mid villafranchian sediments interfinger with the mid pliocene ones. however, the fairly poor biostratigraphic resolution in this area never led the accurate dating of the vertebrate fossil sites that are also scattered in younger deposits, but never indicative of a faunal assemblage of biochronological significance. the upper and lower vardarno basins also had quite a different tectonic history, the latter responding to the pulses of the apennine uplift by mild sea level changes which formed several regressivetransgressive cycles in a circa-littoral environment (benvenuti et al., 1995). short-lived episodes of continental deposition and of minor areal extent are in contrast with the relatively long sequences accumulated in the marine facies. also the pollen distribution was different, recording changes largely reduced in ampliture and testifying a lagunar facies in the vegetation. sedimentation started in the upper valdarno directly with continental deposits, unconformably overlying the turbiditic sandstone of oligo-miocene age, and was affected by two main episodes of the apennine uplifting, which produced deep changes in its lacustrine sequences. these were in fact interrupted twice, for time spans which are now dated to represent long breaks in the history of the basin. similar breaks are expected to be found in the several intramontane basins of the apennine belt, and in the external apennines where are now dated coeval with the upper valdarno breaks (albianelli et al., this volume). 33..11 sseettttiinngg ooff tthhee bbaassiinn the general setting of the northern-apenninic architecture was described by merla (1951), and the upper valdarno disposition in its framework by abbate et al. (1971). a detailed survey of the basin led to the lazzeri (1977) map, from which the sketch of figure 8 is taken. in the present reconstruction only few references are quoted, without discussing the general framework developed since merla's (1951) modern views for the northern apennines and later reproposed with increasing details. the upper valdarno basin was re-visited by merla & abbate (1967) and azzaroli (1967) for their tectonic and biochronologic reconstructions. an updated tectonic and sedimentarry feature was provided by martini and sagri (1993), who restored the asset of the northern apennine basins as reported in figure 1, while the lazzeri (1977) map completed the scheme to which all studies on the upper valdarno record were later linked. a next step will be marked by the detailed new 138 g. napoleone et al. mapping, which is beginning in these days. it will be useful to report more widely on the previous works. the time implications on the history of the basin, until now established by the faunal distribution earlier mentioned, are shortly emphasized, although disregarding the tectonic reconstructions of the basin in relation to the close intramontane structures along the northern apennine belt. the basin is an asymmetrical depression, bordered on the north-eastern margin by the pratomagno ridge, which divides the upper valdarno from the casentino basin, and with a normal fault system of smaller displacements along the south-western margin by the chianti mts (merla & abbate, 1967; magi et al., 1992). these deeply regulated the sedimentary regime, which produced a number of local deposits. they have been grouped in two main sets, better exposed on either side of the arno river bank, one on the western border containing the earliest and latest sequences, and the other on the eastern bank with the richest fossil sites and of median age between the tectonic displacements of the apennine uplift now dated to last half a million years and nearly one million, respectively. during these ages, indeed, the deposition was also regulated by the climatic changes affecting the geologic system at the critical ages of the turnovers to the late pliocene and to pleistocene. they were recorded by the pollen and magnetic signatures, imprinted by their continuous changes throughout the series. therefore, our interest is directed to timing the main events in the history of the basin, which will provide the reference for the similar ones accompanying the time span of the apennine growth. it is notable that this growth also left traces in the external apennine marine sequences and their detailed correlation with the upper valdarno ones will be the next goal in dating the ages of the tectonic phases across the mountain belt. 33..22 tthhrreeee ddeeppoossiittiioonnaall ccyycclleess the upper valdarno sedimentary fill is made of three separate units, each marked by angular and/or erosional discontinuities (billi et al., 1991; martini & sagri, 1993); the bulk of its new asset is represented in figure 2, the dates for their events having been provided by magnetostratigraphy (albianelli et al., 1997; 2002a). it is here used to introduce the general aspects, while a more detailed reconstruction descending from the present study is reproposed in figure 18, with the actual series exposed on both sides of the valley and correlated by their magnetostratigraphy. the first phase developed in the south-western margin of the basin, with the fluvial-lacustrine deposition of the castelnuovo succession. it started with pebble and sand of alluvial fan type; after a while, the fine grained sedimentation developed, and rapidly moved to palustrine clay with thick lignite seams and to a decidedly lacustrine facies. the basin was filled up by sandy fluvial deposits (san donato sand) which are overlain by a more than 30 m thick level of wind-blown white sand, rena bianca (magi & sagri, 1996), recognized in recent cuts to unconformably stand on them. this deposit was the result that followed the strong apennine uplift which displaced and tilted to the ne the lacustrine deposits. for its disposition, it is now assigned to the overlying montevarchi sequence (fig. 2), thus deeply modifying the previous asset of the magnetostratigraphic reconstructions reported in previous papers (albianelli et al., 1997; cioppi & napoleone, 2001; napoleone et al., 2001c). the second lacustrine and palustrine phase developed in the central basin, which occupied a quite larger area than the previous one, with fan-delta deposits in the marginal sides (billi et al., 1991). the former facies is made of clayey-sandy silts, with frequent sand levels containing lignitiferous beds in their middle-upper part; the fan delta facies, in contrast, is made of coarse pebbly deposits passing to channelled sand and pebble. the lacustrine and palustrine sediments are represented by alternating sand and silt levels, grouped in the 80-90 m thick montevarchi succession. the third phase marks the filling of the basin and is separated from the second one by an erosional event, which is now known as a significant one as it represents an extended gap, whose duration still needed to be defined until magnetostratigraphy provided a date for its long duration (see in chapter 4). a fluviatile facies, the monticello succession, crops out in the axial zone, with alluvial fan sediments of the ciuffenna succession (fig. 2), in the vicinity of the pratomagno ridge and mainly in its south-eastern edge. in the wstern bank, indeed, the corresponding facies has released a rich fossil fauna. 3.2.1 the early lacustrine facies in the santa barbara profile a direct view of an outcrop in the open mine of santa barbara is shown in figure 3 and illustrates the full extent of the meleto clays, which were removed for quarrying the 15 m thick lignitiferous level. in the marginal area of the present view, the lignite seam directly lies on the arenaceous basement, which is exposed on the left-hand side of the picture as the wall of the basin 139calibration of the upper val d’arno basin ... figure 8 simplified sketch of the upper valdarno geologic map (redrawn after lazzeri, 1977, and magi et al., 1992). the basic sedimentary sequences are shown, together with some of the fossil sites mentioned in this paper. at the foot of the chianti mts. in the background, about 1 km away, the lowermost sediments are exposed, with the spedalino gravel and sand derived from the oligocene-miocene deposits of the basement, in which few fine-grained limy beds were also sampled for magnetic stratigraphy and palynology. farther off the margin, a few meter thick level of clay underlies the lignite seam and represents the beginning of the lacustrine sedimentation. so, this facies shortly precedes the palustrine one of the lignite-bearing level. the rapid accumulation of the latter, then, quickly moved back to the shallow-water lake deposits in the meleto area and in the extreme north-western edge of the basin. the 156 m section in the foreground of the picture (fig. 3) is in the clays above the lignites and was sampled for magnetics avoiding the more sandy beds; the one in the background was sampled for palynology a few years earlier, for nearly 300 m from the base. the lower part of the sequence, beginning with the aforesaid levels of the basal gravel and sand and nearly a half of the lacustrine clay, is entirely dominated by the pollen of warm, humid forest vegetation typical of subtropical to warm-temperate climates (e.g. taxodium/glyptostrobus type, nyssa, engelhardia, arecaceae, itea, symplocos, cephalanthus, clethraceae, cyrillaceae, myrica, carya, quercus, carpinus, ulmus, zelkova). the basin, after this phase corresponding to the development of a bog, moved toward cooler conditions, with some fluctuations, leading to an expansion of cooler forest; the herbs (including the steppe flora) remain a minor component. then, near the top of the meleto clays, the subtropical forest almost vanished, giving way to a great expansion of the coniferous boreal forests (with a large component of picea). this record is correlative with the reuverian of zagwjin (1960). the thickness of the lithologic profile is reported from the section measured for the magnetic stratigraphy, which was correlated with that for the pollen profile by several markers (fig. 2). it is formed by the clay and lignite seam, which were sampled in the cores of two drilling bore-holes, overlain by a thinner level of siderite before the next lignite seam; then a thick pile of silt extends upwards until the sandy beds begin to increase in thickness and frequency, progressing with the lake filling. these beds are recognized in short sequences from several sites but their total thickness is still tentative. 3.2.2 end of the castelnuovo cycle up to the rena bianca sand the time span for deposition of the san donato sand overlying the meleto clay and of the rena bianca sand is questionable, lacking adequate reference of fossil finds and sufficiently long exposures; only recent cuts for quarrying evidenced the unconformity of rena bianca with the underlying sand. this led to the separation of these two sandy units, which were earlier assumed as two different facies of the sand body separating the first lacustrine cycle from the second one. therefore, the short reversal measured in the lowermost rena bianca unit is interpreted as the gauss/matuyama boundary (fig. 2), and no more associated with the san donato sand as previously reported (albianelli, 1995; albianelli et al., 1997; 1999; cioppi & napoleone, 2001). in the san donato sands, instead, a strong resurgence of the warm forest is recorded by pollen, while at the base of the rena bianca sand, i.e. at the gauss/matuyama boundary, a drastic change has marked the withdrawal of almost all the forest taxa, leaving a profile dominated by herbs including a very large component of artemisia. above this, but still in the earliest matuyama, a great increase in the warm forest taxa and cathaya as well as a strong reduction of steppe elements are recovered. this phase can be correlated with the first glacial/interglacial cycles following the onset of the arctic glaciation reported at 2.6 ma and the praetiglian of zagwijn. an unconformity between rena bianca and the overlying series was never found until the latest intensive quarrying of the rena bianca sands has exposed their contact. the new silty facies is the very beginning of the terranuova unit in the montevarchi cycle, leading thus to the connection of rena bianca with the second lacustrine sedimentation (magi, unpublished data; ghinassi et al., in manuscript) this implies that most of the tilting of the meleto sand unit occurred before deposition of the rena bianca, i.e. in the very short time span preceding the gauss/matuyama boundary, and the rest took place in the longer interval before the new phase placed at nearly 2.1 ma (fig. 2). the pollen record there evidenced -at the gauss/matuyama boundarythe presence of an arid climate vegetation (bertini, 1994; bertini & roiron, 1997). therefore a wind blown origin for it was supported by the dates of the scanty interbedded silt levels at a time when the ice rafting of the pliocene had already started (shackleton et al., 1984). from the (lower part of) rena bianca presumably comes a single vertebrate fossil, the mastodont skeleton studied by nesti (1825) but reported without any account on its location. 3.2.3 the montevarchi cycle in the faella pit section the lacustrine and palustrine deposits of the montevarchi sequence mostly lie in flat bedding with an average thickness outcropping for 80÷90 meters, which is almost wholly included in the section of the faella pit (fig. 9), and its magnetostratigraphic profile is reported in figure 17. they are subdivided into three lithostratigraphic units, the first being represented by 30÷35 m of prevailing sandy silts and sands, the terranuova silt. the second one is a 20÷25 m thick horizon with peat or lignite and clays rich in organic matter, and with silt and sand interbeds, the ascione clay. the third unit is a ca. 30 m thick sequence mainly of sand, the oreno silt and sand, which also closes the lacustrine deposition in the central area of the basin. the surveyed sequence exposed in the faella pit, about half a km southwest of the faella village and on the right bank of the arno river, is ca. 70 m thick. in figure 9 most of its extent is shown in a fresh section (fig. 9a), starting at ca. 150 m level and slightly above the base of the present quarry (143 m). the lower sediments reach an elevation shortly above 185 m, and consist partly of the terranuova silt and the entire ascione clay, while in figure 9b the overlapping portion of the ascione unit extends in the oreno silt and sand, which reaches 207 m in a short section further in the back140 g. napoleone et al. ground. the actual thicknesses of the lithology profile are reported in the magnetostratigraphic profile albianelli et al. (2002a), and reach 134 m at the base of the faella section (napoleone & azzaroli, 2002). on the right-hand bank the horizontal montevarchi sediments are overlain with a small angular discontinuity by the silt and sand of the successive sequence, and upstream (the south-eastern edge of the basin) the fluvial regime deposited the basal laterina gravel (fig. 2). the same gravel marks the unconformity of 15°÷20° dip, due ne, on the left-hand bank, although in the area nw of bucine it seems to lie on the intermediate unit (ascione) of the montevarchi sequence, possibly with a minor oreno level (fig. 10). in the faella section, the terranuova silt is represented by 25 m of mixed levels of more clayey and sandy grey silt, sometimes maculated and often bioturbated and pedogenized, and by sand with variable lime content, in widely extended flat beds. channelled sandy bodies are also present. some 20 m thick peaty clays of the ascione unit overlie the terranuova silt. brownish to grey-greenish clays alternate in beds of various thickness from few cm to some dm; interbeds of sand and silty-sand also alternate with a similar variable thickness. about 25 m of the mainly sandy oreno unit are exposed in the upper section, with thicker beds of sands also containing some lignite seams in a coarser sand-topebble facies which is usually rich in fossils. channelled bodies are here more frequent. a similar sequence was described by cocchi (1867) on the opposite hill of monte al pero, across the faella creek, and correlates with the lowermost faella profile. in the present section, then, the ascione clay is fully represented while the oreno unit is interrupted, partly because its sand was removed for industrial works. a close analogy of this sequence with the one brought to light at tasso (fig. 10), nearly 10 km south of faella, was found while surveying the outcrop for the new railroad tunnel. its sedimentary sequence showed the ascione and oreno units as at faella. the sedimentologic recognition on both sections led to closely correlate the upper ascione unit and basal oreno, and also drove more attention to the same units exposed in the matassino pit, 2 km away and closer to the arno river. even if palynological sampling was carried out in several sections, documentation of vegetational changes is less complete than in the castelnuovo succession and less continuous (bertini, 1994; albianelli et al., 1995). in fact the dominant silty and sandy sediments are generally barren or nearly barren of pollen and spores; in a few cases a high spore abundance along with concentricystes seems due to stream concentration. palynological data show a progressive reduction of subtropical/warm-temperate taxa that are mainly represented, although discontinuously, by cathaya (plus pinus haploxylon type) and taxodium. a sequence of steppeforest alternations, indicative of well established glacial/interglacial climatic cycles is recorded. steppe assemblages are characterized by non-arboreal pollen (mainly asteraceae included artemisia, poaceae, cyperaceae); forest assemblages by thermophilous arboreal pollen (mainly quercus, carya, carpinus, pterocarya, ulmus, zelkova). in particular at matassino, in the level beds from the poggio rosso fossil deposit to the level of nesti's rhino, a glacial-integlacial oscillation is recorded. in the upper part of the oreno silt and sand, at the tasso tunnel section, a significant increase of the herbs percentage (up to 89%) is measured; it is represented mainly by asteraceae cichorioideae, and marks a cold and dry phase correlated with the beginning of the eburonian of 141calibration of the upper val d’arno basin ... figure 9 the outcrop of the montevarchi sequence is better exposed in the faella clay pit. the profile for the lithology is controlled on the detailed survey of the area (magi, 1999), and that for the magnetic stratigraphy is the composition from the sampled sections shown after a fresh cut: in a the lower portion reaches 185 m in elevation, and in b the upper one is exposed, but not up to the end of the sequence, which was sampled up to 207 m level in a short section slightly beyond the peak (modified, after albianelli et al., 2002a). figure 10 the trench opened for the artificial tunnel of the new railroad roma-firenze, yielded the magnetostratigraphic profile shown by the side, and used with the previous one of faella for reconstructing the magnetostratigraphic reference section of figure 16 (modified after napoleone et al., 2001c). zagwijn in northern europe. this trend toward aridity coincides with a partial drying of the basin and a more frequent input of arenaceous sediments. 3.2.4 the third cycle: cava gori and c. minuto pits, on the western bank of the arno river this sequence is rather thin. its base is formed by a 6÷8 m thick gravel bank in the south-western edge of the basin, and by an equivalent sand bank more to the north. the gravel in the southern outcrops generally overlies the clay unit (ascione) of the montevarchi sequence, while the oreno sand is lacking. this is the case with the section in the cava gori pit, which was thoroughly sampled in the occasion of new outcrops which uncovered a 20 m deep well of roman age (fig. 11). the ascione clay underlying the basal gravel bank is tilted 17°; a 4 m thick sand covers the gravel and is followed by 5 m of silt and 4 m of clay rich in organic matter. on top, the coarse material of the final basin fill had been already removed in c. gori, but at pogi, near bucine, it released a rich fauna. downsection, a slice of the ascione unit is underlain by the terranuova silt of several meters thickness; the full profile is reconstructed for nearly 40 m, almost half with terranuova silts and half with ascione clays but either one covered by a few meters and with a relevant displacement in the mid section. the upper lithologic profile fits that obtained in the reduced sequence shown by the side of the magnetic stratigraphy in c. minuto (see fig. 17). the latter is very similar to the uppermost sequence of c. gori, although with minor changes in thicknesses, due to the irregular fluvial deposition. the gravel bank at the base is of comparable thickness, but the clay silt overlying it and containing the elephant bones reported earlier are of reduced thickness due to the nearly complete absence of the uppermost level rich in organic matter. the widespread closure horizon is also present, with a thin bed of sand on top and the gravel, just exploited by the quarrying but still visible in the vineyards by the side. 44.. mmaaggnneettoocchhrroonnoollooggyy ooff tthhee ddeeppoossiittiioonnaall rreeccoorrdd the magnetostratigraphic dating of the upper valdarno sequence was first applied to calibrate single sites with known position of fossil finds, either belonging to actual recoveries (torre et al., 1993; albianelli et al., 1997; 2002a; napoleone et al., 2001b) or to the museum old collections reappraised from the information in the automated catalogue (cioppi & napoleone, 2001; napoleone et al., 2001a). a thoroughly revised dating of the main museum collections is reported in a paper submitted in january 2001 to the bulletin of the italian paleontological society and still unpublished (napoleone et al., 2001c). these localities were placed in the new magnetostratigraphical asset, which was by the way still devoid of several results recently acquired and only now reported herein, while fresh outcrops let to better sample new sites with better behaved magnetic properties. one such sites was the poggio rosso profile, where even the more sandy samples of the series led to measure the acquisition of magnetization under strong applied fields as shown in the next section. the 142 g. napoleone et al. figure 11 the short sequence of the third depositional cycle is shown in the outcrop of the cava gori sand pit during the excavations for recovering the old water well of roman age. the full sequence is represented in the profile by the lithologies surveyed in the walls of the pit and its outskirts. the base of the profile is formed by the ascione clay of the underlying montevarchi series, which was surveyed for almost 40 meters in a partly covered outcrop in continuity with the present section (after albianelli et al., unpublished data). faunal site of matassino, in the same profile, was the prominent locality re-placed once the channelled nature of the previous section measurement produced the misleading value of its age previously reported (torre et al., 1993). finally, the filling series was investigated thouroughly and its late matuyama age is the newest result. this leads to an important role in the history of the growth of the appenine range that will be plaid by the complete range of dates now recorded, the longest series in the continental deposits of the apennines. last but not least, all recent data were made possible by the new recognition in the sedimentary sequence of the unconformity between the san donato and rena bianca sands which permitted to place the gauss/matuyama boundary in the basal rena bianca and identify in the overlying silts the short reunion chron (fig 2). the tabulated data from the measurements yielded the results here illustrated in a few figures by some representative diagrams, in order to focus the main aspects in the rock-magnetic properties associated with the upper valdarno lithologies, which provided the fundamentals for its magnetostratigraphy. 44..11 mmaaggnneettiicc pprrooppeerrttiieess ooff tthhee rroocckk ttyyppeess the problem of stability of the magnetic signal is of major concern in studying sedimentary sequences of rapid accumulation, as experienced in the present deposits on continental slopes, for the bacterial activities which reduce the iron oxides to sulphides. these can be very unstable under laboratory tests, by either changing with temperature into another mineral phase (magnetite) or being incapable of maintaining a regular track of their natural remanent magnetization (nrm) under applied fields with alternative currents (af). such a behavior was shown by the most representative early pliocene rock type of marine facies, in southern sicily, and by the lacustrine clay very rich in organic matter, close to the lignite seam at santa barbara (albianelli, 1995). these occurrences are enhanced by the following three main precedures. saturation of the isothermal remanence (irm), nrm stepwise demagnetization and the curie balance curves are among the more usual ones used for evidencing the basic rock-magnetic properties. with the first type of experiments, the degree of irm acquired along the three axes is shown by its demagnetization curves, which remark the low coercivity of ferromagnetic minerals. in the second one, visualised in zijderveld’s vectorial plots, the trend of the directions converging to the origin of the axes, while demagnetizing the rock sample, are indicative of a stable primary magnetization, not influenced by the secondary ones. with the curie-balance experiment, the acquisition of the remanence by a rock sample is enhanced while it is cooling in a strong applied field after its complete demagnetization with stepwise increasing temperatures. these tests were applied to the surveyed sections, and their lithologies showed a variety of different behaviors. sometimes such changes assumed a wider range within the same sequence rather than between the three main depositional series. depending on minor changes in the mineralogical content of their ferromagnetic particles, and related alterations suffered during their geologic past, the main types will be shortly illustrated in some examples for their good rock-magnetic properties on which the magnetostratigraphic interpretations are based. 4.1.1 meleto clay in the castelnuovo cycle as for all the other units, the basic lithology formed by silt is varying in a wide range of more sandy compositions: the stage of a complete sand bed is reached with marked discontinuities within the meleto clay. the most common representative of the rock type is here shown for only some of the measured characters. for example, in two samples of the meleto clay, different sulphide content can be demonstrated in beds overlying the lignite seam, one (sb -12) less than 5 m above its top and one (sb 27) 44 m higher up (fig. 12). the magnetic remanence is steadily decreasing versus temperature, to ca. 300÷400 °c, above which a remanence is added by new-formed minerals, essentially magnetite. the occurrence of sulphur compounds is common in marine and continental sediments of recent geologic ages and of rapid accumulation, depending on the redox conditions at the bottom surfaces where anoxic conditions lead the bacterial activity to reduce iron oxides of the magnetic minerals. this behavior was particularly diffused in the marine carbonates of the early pliocene sequence in southern italy, which showed a very unstable behavior and the diagrams for the curie-balance experiments enhanced peaks even more prominent than the ones here reported (albianelli, 1995). also the nrm reveals the presence of such perturbations in the rock composition, and is evidenced in the zijderveld plot where the directions are projected in the vertical plane z (inclination) and in the horizontal one h (declination), for every step of the demagnetization procedures. a onecomponent primary magnetization would show a straightforward trend to the axis origin, while perturbations at various demagnetization steps would enhance additional vectors which are being removed. the presence of a new magnetic phase, as in the previous example, would make the directions completely out of the steady demagnetization pattern: for this reason the values for a sample (sb -1) 11 m above the previous one (sb -12), are not plotted for temperatures higher than 300 °c, as the direction is suddenly diverging 143calibration of the upper val d’arno basin ... figure 12 diagram of the curie balance measurements carried out on two samples of the meleto, one (sb -12) from a level very close to the top of the lignite seam and another one (sb 27) some 40 m higher up. their magnetizations are decreasing at increasing temperatures, until a rapidly increasing value is measured around a critical range of 300÷350 °c, interpreted as a new magnetic mineral phase produced by oxidation of the sulphide contained in the rock. this content is markedly higher in the levels closer to the organic material, strongly decreases at 40 m level, and is absent farther up in the series. and the susceptibility sharply increasing. in contrast, the level bed at 46 m (sb 29) is devoid of these alterations. the latter type of diagram is available for every sample, as in all of them a number of demagnetization steps were used in order to control more accurately the changes measured, up to the highest step before alterations could interfere with the normal trend, or to the lowest magnetic moment detectable. the latter was that of the magnetometer of the eth paleomagnetic laboratory in zurich, and the measured signal provided fully reliable intensities for magnetizations in the range of 10-8 uem/gr. 4.1.2 the montevarchi units the few levels with fine-grained limy beds in the coarse grain unit of san donato sand and finer sand in the rena bianca usually enhance low nrms, which rapidly decay to undetectable values not further than 300 °c. in the overlying montevarchi sediments the general characters of the rock magnetic behavior are similar to the meleto types, with a more common occurrence of oxidized material of higher coercivity, able to reach higher blocking temperatures in samples with higher silt and sand contents. the experiment for irm saturation in the orthogonal directions, with its demagnetization, adds one more evidence of different behaviors of the carriers of the magnetization. two examples of this test are also shown (fig. 13). for each of them, two diagrams show the acquisition of the magnetization and its differential removal, to represent the behavior of a clay (gt 13) in contrast with a silt (f 48). in the first two diagrams on the left, the magnetization rapidly increases, in the range from 50 mt to 200 mt of an applied field up to 1 tesla (t). the upper sample represents the saturation for the low coercivity minerals, which is normally attained in that range; the lower sample represents those of high coercivity, which do not reach the saturation, requiring stronger fields (usually up to 5 t, or more). on the adjacent two diagrams , the three components of the magnetizations acquired show their decay curves, which are in the great majority of the measured samples showing low blocking temperatures for minerals with low coercivities. in sample gt 13, the component acquired up to 100 mt contains the total amount of the magnetization and practically nothing is left to the other two. the only one blocking temperature is interpreted to be that of magnetite as the sole carrier of the magnetization. the opposite occurs in sample f 48, with a first branch of the diagram relative to a low coercivity mineral phase, and a superimposed one not reaching the saturation up to 1 t. the minor phase showing a low blocking temperature is likely associable to other ferromagnetic minerals including sulphides; another one not yet destroyed at 600 °c, is interpreted as hematite. the same properties are evidenced by the related demagnetization curves of nrm, on the right hand diagrams, for two samples, one at the same level gt 13, and the other, f 45, with the same lithology as f 48. another example (fig. 14) shows two samples from the level beds close to the poggio rosso fossil site, whose nrm is demagnetized by thermal treatment and by alternative fields af. the fairly straight pattern of the af curve in also an indication of the absence of sulfides, whose instability produces random directions 144 g. napoleone et al. figure 13 an example of the irm saturation for two samples from the tasso section (gt 13) and faella section (f 48); their remanence acquired on the three axes is thermally demagnetisedin order to show the blocking temperature of the minerals associable to different coercivity ranges. the next two diagrams on the rigth show the nrm demagnetization for two similar samples, plotted in the zijderveld polar diagrams. 145calibration of the upper val d’arno basin ... figure 14 at poggio rosso, in the series of the second sedimentary cycle, the demagnetization of the nrm is shown by applying either the thermal treatment to a sample of sandy silt shortly above the fossil site, or that of the alternative fields af applied up to 160 mt. both treatments destroy stepwise their remanences, in order to enhance any superimposed field fixed after the primary one, which is well preserved in the original directions. during successive demagnetization steps. 4.1.3 the uppermost units the final deposits of the upper valdarno, exposed at the cava gori, are represented by a sample of the uppermost silty clay (cgn 14), which is compared with a reversed one from the unconformably underlying unit of the montevarchi sequence (fig. 15). both levels are made of the same material, although their dates are nearly 1 my apart, as shown in the next section. the silt is in both cases more clayey and peaty, and the samples are taken from very fresh outcrops. the reversed one, cgv 33, shows the removal of a weak component with normal magnetization, usually due to the present normal polarity acting for the recent geologic past, which is rapidly cancelled in the initial demagnetization steps. both sand levels and the thin beds of fine sediment in the lower half of the cava gori profile (fig. 11) revealed poor rock-magnetic properties, with their nrms very weak and demagnetization curves of rather unstable directions, indicative of a transitional field, which was instead better recorded in cava minuto with a decise reversal (fig. 17). 44..22 mmaaggnneettoossttrraattiiggrraapphhyy iinn tthhee rreeffeerreennccee sseeccttiioonnss the sedimentary reconstruction of the basin is now being completed, and it led to the selection of the sections for the paleomagnetic surveys, on both sides of the arno bank. on the left bank, the first cycle of sediments is displaced by a significant lowering on its eastern flank so that it is exposed only in the western bank, from the gravel and clay underlying the lignite seam to the meleto clay, and up to the rena bianca. the dates there measured mark the steps from 3.3 ma to 3.1 ma, up to 2.1 ma, respectively. the full sequence of the second lake is represented on the right bank of the arno river by generally flat beds, except the lowermost ones which are not exposed; it spans from nearly 2.1 ma to 1.7 ma and covers almost completely the montevarchi series. in the left bank, this sequence is partial, interrupted for long intervals and dipping 15°÷20° to the nne. the unconformity cuts there nearly half of the montevarchi sequence, as the basal gravel of the third cycle directly overlies the ascione unit, while the lower series of the terranuova silt is present only with its upper portion. the third cycle has been surveyed in two outcrops on the right bank and two on the left bank, all in quarries exploiting gravel and sand. its basal gravel yielded on both sides reversely magnetized levels in the few limy figure 15 in the sediments of the third cycle, at the cava gori sand pit, a sample with reversed magnetization is thermally demagnetized, in the same way as the previous samples, and is compared with a sample of normal magnetization collected in the underlying outcrop belonging to the ascione unit. beds, but followed by the normally magnetized ones in the silty sequence of the western bank. 4.2.1 dates from 3.3 ma to 2.1 ma, santa barbara and rena bianca sections the gravel in the earliest sediments is devoid of measurable levels, except for few thin silty beds with reversed polarity. the few-meters clay level above it was no longer exposed at the time of the paleomagnetic survey, and the section for magnetic stratigraphy was sampled in the outcrop starting above the lignite-bearing clay directly lying on the basement. it was later completed downwards by cores drilled in two bore-holes, less than 100 m away from the outcrop, towards the inner lake, where the lignite seam is followed downcore by a few meter thick clay level overlying the sandstone basement. a normal polarity is measured in the lower core, and a reversed one in the higher clay and in part of the lignite, while further up the rest of the lignite and the clay yield again a normal polarity. this persists until the end of the section. its magnetic stratigraphy is interpreted as the latest gauss normal polarity following the kaena reversed one (albianelli et al., 1997). above the lignite-bearing level, the series continues some 400 ky in the meleto clay (albianelli, 1995). in fact, from the magnetostratigraphic constraint of the kaena boundary the duration of the sequence was calculated by spectral analysis of the magnetic record, which marked its continuous changes in the milankovitch index-forced sedimentation, to last 60 ky before the end of the gauss chron. the cyclicity-driven changes are discussed elsewhere (napoleone & albianelli, 2002), and they also date the onset of the alternating vegetational associations of warmer and cooler climatic intervals, starting in the mid pliocene and preceding the ice-rafting of the glacial-pliocene (shackleton et al., 1984; demenocal & bloemendal, 1995). the overlying sand unit (san donato sand) is not in continuity with the profile of figure 3, and yields a normal polarity in the few measurable silt levels. further up, two levels with a normal and reversed polarity are measured and labeled as marking a short interval containing the gauss-matuyama boundary. this latter was felt to be positioned only when the cyclostratigraphic processing of the magnetic signal through the time series of the meleto clay yielded the full extent of the latest gauss, except the last 60 ky before the boundary. these results were reported in several meetings, from the ias of 1998 to the gsa of 1999, the euromam in 2000, and on the sepm integrated cyclostratigraphy in, 2001, for which the final study is in the press (napoleone & albianelli, 2002). in the wind-blown sand complex above the san 146 g. napoleone et al. figure 16 the magnetostratigraphic profile of the faella clay pit, valid for the whole montevarchi series. the lower portion is provided by the faella section, and the upper part, by the tasso tunnel section,. the lithologic profile is that of cava faella, to wich the positions of the museum collection of the faella local fauna are associated. thus, the localities of the montevarchi series are calibrated to the faella composite magnetostratigraphy and the vrica stratotype is reported for reference. donato sand, few levels were useful for sampling. the final figure is still under discussion, but the results support the occurrence of a short reunion chron, just above the end of the rena bianca sand and in the following montevarchi succession. this updated version is reported here (fig. 2), and a more detailed profile is reproduced in figure 18. 4.2.2 the interval 2.1 to 1.7 ma in the faella section after the reunion, recorded above the condensed series of wind-blown sand, the sedimentary history and its continuity with the overlying sequence in the matuyama has not yet been fully recognized. in the western bank, the rena bianca is overlain by the terranuova silt for a few meters; in the eastern bank the terranuova silt extends over a thickness of several tens of meters, but the contact with the underlying unit has never been uncovered. this disconformity has an estimated duration of less than 100 ky, after the magnetostratigraphic reconstructions made so far on the outcropping sections, while more data from a bore-hole core extend the series few ky earlier in the reversed magnetozone (albianelli & napoleone, unpublished data). in fact, the earliest fossil is dated 1.99 ma at faella while the terranuova silt extends at least 20 m below it in the outcrops, and possibly 20 more meters, as cored in the bore-hole drillings at terranuova. this sequence, at the rates of deposition calculated by albianelli et al. (2002a) and discussed in napoleone and albianelli (2002), would add ca. 100 ky, and therefore the earliest date be extended to 2.1 ma. from the bottom, the identification of the reunion leads to a date of 2.24 ma (in the time scale of baksi, 1993) as a lowermost limit, with some more space available to shorten this 150 ky gap, which becomes much shorter with the date of 2.14 ma used in the scale of berggren et al. (1995). the geological setting of the montevarchi complex indicates a wide distribution of its three units, which are exposed frequently by quarrying operations. a nearly complete magnetostratigraphic succession is reconstructed on the right-hand bank. from the missing contact with the rena bianca sand, its lowermost exposures are at the arno level, and not in continuity. they are overlain by the faella section, the longest and most continuous one, forming the profile for the central lake sequence (fig 18). in the western bank, the montevarchi beds are interfingered with the upper levels of the aeolian sand younger than the reunion, therefore not reaching a date of 2.14 ma. also the upper limit is not calibrated, the youngest date being measured in the eastern bank shortly after 1.77 ma, in the oreno sand; some more 50 ky may be expected in the last 20÷30 m of the highest sequences, considering the sedimentation rate calculated by spectral analysis of the continuous magnetic record (napoleone & albianelli, 2002) and the average rates shown by the detailed magnetic stratigraphy (albianelli et al., 2002a). therefore a date not younger than 1.70 ma would be reached. significant geochronologic results relate to this interval. downsection from the base of the olduvai at 1.95 ma, the earliest fossil occurrence dates 1.99 ma, with the new recovery in january 2000. the top of the profile did not yield any positioned fossil site and also the end of the olduvai was better defined in the tasso tunnel section. therefore, the magnetostratigraphic section is produced from the composition of the two (fig. 16), and adapted to the profile shown in figure 18. the entire sequence also provides the base for correlating several profiles surveyed in the montevarchi units, usually with an accuracy within 5 ky. the most important one is the matassino section where the base of the olduvai was first identified (torre et al., 1993). for its geochronologic implications, see the discussion in napoleone et al. (2001b). the section of monte al pero, adjacent to the matassino section, was surveyed from top to 20 m above the ground-level of the matassino clay pit; only one normal polarity was measured, as occurred also with the normal polarity in the poggio rosso section. both sequences were correlated with the faella section (fig. 16). more implications arise after the new results from several cores drilled in the upper sequence and at its base, thus extending the magnetostratigraphic profile, downward in the terranuova silt and upward in the oreno sand, but details on these data will be reported elsewhere (napoleone et al., in preparation). the preliminary results extend only by a few meters the lower profile in the reverse polarity, but they produce important implications in the upper profile because a normal polarity is measured for several meters on top of the sequence. this part is recognized in the latereto sand of the upper series, discussed in the next section. the total time span of the measured series ranges from nearly 2.05 ma to 1.75 ma, while an estimate for 147calibration of the upper val d’arno basin ... figure 17 at cava minuto, 1 km away from cava gori, the sediments of the third cycle are represented by a less complete sequence, but in the basal gravel two lenses of silty clay are better developed than in the c. gori and their magnetization is with a reversed polarity. above the gravel unit the polarity is normal as in c. gori (after napoleone et al., unpublished data). the remaining parts not yet found in the exposures would add some 50 ky to both extremes. 4.2.3 the upper series at cava gori and c. minuto the sedimentary cycle above the montevarchi succession started again without any striking gap recorded by sedimentary or tectonic discontinuity. the faunal record was totally lacking in the eastern bank, except one frontal skull of a bovid, while on the western bank the faunal record occurred only in the uppermost filling, on the surface. on the right-hand side a reversed polarity was measured at cava specchiano, and a normal one on the opposite bank, at cava gori in the monteleone area. the first magnetic polarity dating is from the fine grained levels in a less than 10 m thick gravel deposit. it stands as an isolated reversely magnetized interval in the matuyama, and a date for it was questionable; a moderately young matuyama date was only reported as tentative (albianelli, 1995; cioppi & napoleone, 2001). in the cava gori profile, which also unconformably overlies parts of the montevarchi series, the normal polarity measured in the sand just above the gravel, correlative with that of c. specchiano and farther up in the latereto silt, may imply a post-matuyama chron (albianelli & napoleone, unpublished data). at present, this reversed matuyama level is considered to shortly precede the jaramillo or brunhes chrons. it would imply that a lack of nearly 0.7 my or 1 my, respectively, affected the sedimentary record, beginning soon after the end of the olduvai. the sequence is there tilted by 17°, and the magnetic stratigraphy of the profile reported in figure 11, is used to reconstruct the comprehensive upper valdarno series (fig. 18). an important date is added here by new results (napoleone & albianelli, unpublished data) from the analogous section at cava minuto (fig. 17). this profile is a little shorter than at c. gori, its lower sand level being actually missing; the basal gravel on the contrary contains two episodes of fine grained silt, which both yield a very stable reversed magnetization; above the gravel, the silt containing the fossil site and the remaining sequence show a normal polarity. this sharp time signal can be represented as in figure 18 and its date should correspond to a postolduvaian polarity change, which can only be the jaramillo or brunhes chrons. in such conditions the choice of any one of them cannot be solved because the basin fill is devoid of any further step; on the other hand, the previous results provide a fundamental date to reconstruct the history of the basin. the long time span implied in the previous considerations, during which no sedimentary record was preserved, ought to be recognized in the geological processes taking place in the basin and recorded in some way. 44..33 tthhee ssuummmmaarriisseedd mmaaggnneettiicc ppoollaarriittyy sseeqquueennccee a new magnetochronology has been brought about by the results discussed so far in this chapter and its comprehensive features better enhance several details (fig. 18). magnetostratigraphy of the thick first sequence interval yielded a date of ca. 3.3 ma (at the mammoth chron, c2an.2r) for the basal spedalino gravel and pebbly sand, and ca. 3.1 ma for the lignite seam, which began depositing shortly before the kaena (c2an.1r). the succeeding clay sediments attained a variable thickness (100÷200 m), and their layers became progressively more closely interbedded with sand levels while approaching the gauss-matuyama boundary. the sequence was calculated to end at 2.64 ma, shortly before that boundary (2.58 ma), while the record of the short reunion chron c2r.1n (2.15 ma) has now 148 g. napoleone et al. figure 18 the complete reconstruction of the lacustrine sediments is represented in the lithologic profiles from both sides of the arno river bank. the first lake is represented only by the long sequence outcropping in the western bank; in the eastern side the exposures begin with the second lake, and are well developed. correlation with the western bank is marked by the occurrence of the olduvai chron and its underlying matuyama; the former is interrupted in the ascione clay unit, while the short polarity sequence above the unconformity is dated to the jaramillo chron (or later, to the brunhes). its equivalent in the eastern bank has not been measured in the central area, and has yielded only one reversed polarity in the southern area, at specchiano. the olduvai and correlated with the deposits retrieved in 1862 by cocchi (1867), as emphasized in napoleone et al. (2001c). these represent the earliest fossil finds, over 1 my younger than the fossils from the preceding castelnuovo succession. the biochronologically youngest fauna of tasso, elevated to the rank of reference unit (azzaroli, 1977a; 1983), is believed to come from the upper levels. it is assembled by all unpositioned specimens from the old collections; only one site was reported by bosco (quoted in azzaroli, 1998) for two porcupine skulls at le strette, 183 m in elevation. nearly the entire series of montevarchi is now assigned by the magnetostratigraphic reconstruction to a late pliocene age (albianelli et al., 2002a); while the boundary of the pleistocene is calibrated in the oreno unit, at 195 m of the faella composite section (fig. 17). the latest fauna, at the very end of the basin fill provided the greatest new results, i.e. a date for it is firstly reported herein. it is fixed at 1.0 ma and replaces the previous age of late middle pleistocene by precise stratigraphical constraints for reconsidering the whole biochronologic history of the basin and its palaeoenvironmental reconstructions. 55..11 tthhee eeaarrllyy vviillllaaffrraanncchhiiaann ffaauunnaa mmnn1166aa aatt tthhee kkaaeennaa//llaattee ggaauussss bboouunnddaarryy ooff 33..1111 mmaa the fossil finds assembled in the castelnuovo dei sabbioni fauna (mn16a) were collected only in the lignite-bearing level, whose base is older than the beginning of the kaena chron (ca2n.1r), at 3.11 ma, and in the clay beds interfingered with the top of the lignite, at 3.04 ma. a date shortly earlier than this boundary may be assigned, 3.07 ma, with an uncertainty even better than ± 0.02 my, considering that the lignite seam could represent a rather short-lived event in the sedimentary record (fig. 2). its time span may be reconstructed by the magnetic cyclostratigraphy carried out on the meleto clay series (albianelli et al., 1999; napoleone & albianelli, 2002). the clay above the lignite-bearing level yielded an accumulation rate of 220 mm/ky, progressively increasing, up to 390 mm/ky on top; at that lower rate, a 15 m thick lignite bed would last 2/3 of 100 ky, and a rate only twice higher than that one for the clay would lead to the mentioned size of ± 0.02 my in the error bar on a date close to 3.11 ma. it is also reminded that the early villafranchian record of the castelnuovo fauna was classified as contemporary with the triversa faunal unit from villafranca d'asti and the latter will be described in the next chapter. the calibration of the castelnuovo fauna puts a tight constraint on the faunas of triversa and arondelli in piemonte, the latter correlating with the other one in the lower valdarno provisionally taken as an undefined lmf assemblage, but dated quite younger than triversa (to be discussed in next chapter 6). 55..22 mmiidd vviillllaaffrraanncchhiiaann:: tthhee mmaassttooddoonntt iinn tthhee eeaarrllyy mmaattuuyyaammaa,, 22..5588--22..1155 mmaa faunas of this age are labeled in the mammal classification as mn16b. its reference faunal unit was the montopoli association, not represented by an equivalent local fauna in the upper valdarno record, but highly significant for the major turnover it marked in the 149calibration of the upper val d’arno basin ... been found shortly above the rena bianca sand in one of its few exposures. the following matuyama time is recorded in the lower montevarchi silt, and the olduvai in the overlying units. the late olduvai however recorded an important event in the split polarity reversal, which is dated 1.815 ma and 1.785 ma in the p/p stratotype boundary (1.796 ma), before the end of the chron at 1.77 ma. the latest sediments are not calibrated by a polarity sequence, due to the short length of profiles, and the date near 1.05 ma reported above is alternative to the one at 0.78 ma. the lithoand magnetostratigraphic profiles are summarized in the two reconstructions made from the opposite banks of the arno (fig 18), while the previous magnetostratigraphic framework was reported for convenience in the introduction (fig. 2). the discussion on the dates for each faunal interval, for the ca. 2.5 my surveyed in the basin will follow below, while the results from cyclostratigraphy, reported in the references quoted above, mainly relate to the climate and sedimentary changes for these critical ages of the recent geological time. 55.. ddaatteess ffoorr tthhee uuppppeerr vvaallddaarrnnoo ffoossssiill vveerrtteebbrraatteess most events of the villafranchian age were recorded in this basin, and the dating of its sediments is related to calibration of the middle and late pliocene and beginning of pleistocene. correlation with the bio-chronostratigraphy is updated to the revised one of berggren et al. (1995), and calibration of the pleistocene boundary is related to that of the vrica stratotype (van couvering, 1997). an attempt at uniforming various stages of vertebrate associations in the mammal neogene (mn) age classification assigned the villafranchian to the relative ages mn16 and mn17 (mein, 1990). for the aforesaid reasons, azzaroli (1995) split the mn16 in mn16a for the early villafranchian and mn16b for the middle villafranchian, pointing out that the major faunal turnover occur between the triversa and montopoli fu at the late pliocene boundary (azzaroli, 1983). whereas the faunas of montopoli and olivola respectively of middle and late villafranchianwere collected outside of the upper valdarno, from single pockets with a rich concentration of bones and a variety of species, the early villafranchian fauna of castelnuovo was dispersed, even if the few species lived for a presumably short time span within/or across the lignite-bearing level. in contrast, the rich fossil-bearing montevarchi succession is widely distributed and tightly constrained by several magnetostratigraphic tie-points, after a long gap occupied by the condensed series, which has now been dated to range from the gauss-matuyama boundary at 2.58 ma to the reunion at 2.15 ma. the montevarchi sediments extend from the vicinity of incisa in the north-west to around bucine in the south-west, with a length of over 20 km, and fossils are distributed in horizontal deposits ranging from approximately 130 to 230 m in elevation. the fossil-bearing levels lie in either one of the ascione and oreno units overlying the terranuova silt, and in the latter as well. in the terranuova silt , in particular, the fossils collected from the basal faella clay pit at 134 m are calibrated before biodiversification of the terrestrial fauna in western europe and southern russia (azzaroli, 1983; 2001). with the magnetostratigraphic calibration, it is established that during the mid villafranchian age the upper valdarno record was mostly formed by subaerial deposits, for a more than 0.4 my time span (fig. 2) and in a well established regime of glacial-interglacial oscillations partly recorded by the pollen distribution. thin limy beds within these wind-blown sands have recently shown the end of the reversed polarity alternating with the normal one, which leads to the recognition of the presence of the reunion chron c2r.1n immediately above the transition to the silt of the following lower deposits (albanelli & napoleone, unpublished data). the only one finding of vertebrates, attributed by azzaroli to possibly belong to this sequence is a nearly complete skeleton of a mastodont found in the vicinity of the montecarlo convent, on the hilltop on the left bank of the montevarchi basin. the fossil was excavated in early eitghteen hundred and was summarily described, without an exact indication of the site, by filippo nesti in 1825, who did not report on the stratigraphy of the upper valdarno in that occasion. in 1811, in contrast, he gave precise indication for the location of the rhinoceros of poggio di monte al pero and of the geology of the montevarchi deposits (nesti, 1811). the anancus of figure 4 is from the castelnuovo sequence but considered somewhat younger than the castelnuovo dei sabbioni fauna, although its recovery was not reported and location is unknown. the montecarlo convent is built on deposits of the second cycle, but not far west the hill slopes down and overlies deposits of the rena bianca unit. the skeleton may safely be assumed to come from the latter formation. it is practically complete (only the tusks are missing; in the exibition of the museum they were replaced). the specimen is of a large size, nearly 3 m high at the withers. it slightly exceeds the size of a mastodont from valleandona in piemonte, west of asti, summarily described and figured by capellini (1908). to judge from the shape of its pelvis, it seems to belong to a female. this famous specimen in the paleontological collections of the museum of firenze was ascribed to the mid villafranchian, as it was last represented in the montopoli fauna. another specimen of anancus was reported in the marchesa paulucci collection, donated in the early 19 hundreds to the museum of firenze (cioppi et al., 2001); it consists of a tusk and a molar whose position is believed by azzaroli at the base of the hill on top of which her villa is positioned at sammezzano, on the right bank of the arno, in the middle of the area of the montevarchi terranes, but the fossil site cannot be better identified. 55..33 llaattee vviillllaaffrraanncchhiiaann:: ffaauunnaass ooff oolldduuvvaaii ttiimmee ddaatteedd 11..9999--11..7777 mmaa this mammal age is covered in the upper valdarno by the montevarchi sequence which is represented by the outcrops on the eastern bank of the arno forming the profile of the central lake (fig. 18). the whole sequence is particularly well documented by the detailed dates of its finds, but it is unfortunate that the majority of fossils of the older collections, ca. 75% of the upper valdarno vertebrates in the museum, do not bear an indication of the locality nor of the exact level of provenance. almost all of the series has been calibrated to the late pliocene age, and the dated fossil record spans 220 ky from 1.99 ma in the faella section, including the pleistocene boundary sited in the oreno unit. as said before, this section has recently provided the oldest specimens. out of faella, the matassino deposit represented until recently (gliozzi et al., 1997; torre et al., 2001) the first fauna of the late villafranchian, which had been classified as coeval with the olivola faunal unit for their affinities (azzaroli, 1977a). magnetic stratigraphy of the matassino section identified this locality to stand ca. 10 m above the base of the olduvai, and its date to be quite younger than 1.95 ma (torre et al., 1993). a new determination has been made in the summer of 2002, sampling a profile adjacent to the previous one and where parts of an elephant have been later collected. it shows that a 12 m thick normal polarity was brought in by channelled sand embedded in a reversed magnetozone (napoleone & albianelli, unpublished data). a further profile, sampled closely by the side of the channelled deposit, led to the reconstruction of the classical old locality as sited just at the base of the olduvai, and its date at 1.95 ma, replacing the previous profile which produced the misleading date of latest olduvai. in the same clay pit, the poggio rosso site is 30 m above the matassino site, and its fauna forming the richest assemblage collected in the upper valdarno is dated 1.87 ma. this value is the result of the cyclostratigraphic analysis of the magnetic signature (napoleone & albianelli, 2002) and of the correlation with the faella magnetostratigraphic section (napoleone et al., 2001b). to the se of the matassino hill, the rhinoceros studied by nesti in 1811 was collected near the top, at poggio di monte al pero and located shortly above the poggio rosso fauna: it was dated ca. 1.83 ma, being correlated with the faella reference section. the same date has been given the rhinoceros skeleton recovered in 1999, while the elephant collected by azzaroli in 1953 is estimated to be slightly older, 1.87 ma (azzaroli & napoleone, in manuscript). the old collection of faella is centered at a level higher than the latter site and a younger date was assigned to this part of the faella lmf, at 1.82 ma, while the elefant of 1949 would be even younger. the large tusk collected on the road to siena, west of montevarchi, was excavated in the upper oreno sand and represents the youngest dated specimen of the montevarchi series (fig. 16); it is labeled as azzaroli’s elephant only for graphic covenience. several other large collections do not have a magnetic stratigraphy, or their sites are not positioned. however, from the previous results some inferences restrict their dates to a narrow range of uncertainty. first of all, the casa frata fauna was collected near the section of the tasso tunnel, in the upper ascione beds close to the transition to the oreno sand, which in that profile is in the portion of the olduvai ending at 1.815 ma. the casa frata fauna is therefore placed in figure 16 quite older than this date and likely close to 1.85 ma. the problem with the tasso faunal unit is similar. few detailed indications were given only on the porcupine of bosco (azzaroli, 1998), referred as positioned at le strette al tasso, an area around the small water gap 150 g. napoleone et al. of the tasso creek, where the farm labeled as le strette on the official map of the national topographic survey is reported at 183 m. as a consequence, the biochronologic constraint that the tasso faunal unit (to which this porcupine belongs) follows the poggio rosso and casa frata faunas imposes that all specimens of the assemblage should have been recovered in level beds quite higher in the series and not in the lower oreno unit still datable in the late olduvai. although not fully calibrated, the oreno sand would not reach the date of 1.70 ma: at most, the tasso faunal unit, sited in the short interval of the oreno sand would be dated from shortly before the p/p boundary to shortly later, for example between 1.8 ma and 1.75 ma. in figure 20 its position is stretched towards this upper limit. the totality of the fauna dated so far did not range beyond the late pliocene; only a minor part, before its calibration, is expected to actually be of early pleistocene age, and lasted very few ky. also another proxy is in the same condition, the pollen record, which does not reach the pleistocene boundary, as reported elsewhere (albianelli et al., submitted). at very few ky before the boundary the pollen record attains the highest percentage of herb sporomorphs, indicating a steppe vegetation of glacial facies. deposition becomes more sandy and its rate close to that of the san donato sand. all fossils from this succession were assigned a wide range of dates in the early pleistocene, and with this age are reported in the gef automated catalogue (cioppi et al., 1996). no site has been measured yet in the pleistocene, as it is located in the p/p stratotype (van couvering, 1997). therefore one might argue that early pleistocene representatives are barely present in the palustrine sequence of the upper valdarno, considering that the two skulls of hystrix etrusca, from le strette, se of terranuova, were found in a site which lies near the unfossiliferous wall opened for the tasso tunnel. in this section the end of the olduvai chron was measured at 205 m level and the pleistocene boundary placed at 195 m (figs.10, 16). the remaining fauna from the undefined localities of the tasso mammal unit might be considered in a similar condition. it was never fully studied from the palaeontological point of view, and none of its specimens was sited precisely in the several findings from the tasso localities, le strette al tasso, il tasso, ville al tasso, etc. these all belong to the upper montevarchi series, but a stratigraphic resolution better than ± 20 m would add a slightly more precise age of no more than 50 ky around the end of the olduvai at 1.77 ma, except to slip back and forth across the pleistocene boundary. 55..44 tthhee ppoosstt--vviillllaaffrraanncchhiiaann ooff bbuucciinnee aatt tthhee jjaarraammiilllloo bboouunnddaarryy,, 11..0055 mmaa the rich faunal assemblage collected on the surface in several sites of the pogi area near the town of bucine, belongs to the gravel of the latest filling of the basin, best represented by the cava gori lithologic profile. the magnetostratigraphic profile of the adjacent cava minuto gives, instead, a prime result for the history of the upper valdarno: the lower portion, in the reversed magnetozone, puts the lower limit of the basin fill not younger than the transition from villafranchian to the galerian mammal age. in the meantime, the fossil site of cava minuto would summarize the thin horizon of the bucine fauna and yield a date of the onset of the normal polarity interval. however, its range would be very narrow, as the recoveries at pogi had been in the upper gravel, no more exploited, but in the same horizon which closes the basin fill at cava minuto, and just following in the normal polarity the elephant bed. therefore, a younger limit could reach the date of 0.78 ma, to which the beginning of the middle pleistocene is calibrated to the gpts, and an older one would be dated shortly more than 1 ma. a date very close to 1 ma or to 0.8 ma would be provided for both, the fossil collected at cava minuto and the ones at pogi. these dates build a completely new framework for the history of the basin, which now is more clearly understood also in relation to the other northern apennine basins. the calibrated faunas there recovered (see in the next chapter) do not exceed a date younger than the brunhes boundary and more likely jaramillo. only the bucine lmf would have reached an age as young as a late middle pleistocene, which has to be rejected in absence of stratigraphical supports, while the present magnetochronologic framework puts immediately the constraints on the age of the elephas antiquus recovered in october 2001. 66.. cchhrroonnoossttrraattiiggrraapphhiicc ffrraammeewwoorrkk ffoorr tteerrrreessttrriiaall ffaauunnaass ooff tthhee iittaalliiaann ppeenniinnssuullaa the time span elapsed for the deposition of the upper valdarno sediments, during the villafranchian mammal age, is now calibrated by magnetic stratigraphy to the middle and late pliocene, and to the earliest pleistocene. these accurate dates are applied to date the fossil sites and the palaeoenvironmental changes which affected the apennine basins. for these ages, in fact, the faunas of the main localities of the italian peninsula, recently reconsidered by azzaroli (2001), are now recognized in stratigraphic order. their distribution is mainly located in the northern apennines (fig. 19), and correlation is made with the same criteria as for the biostratigraphical series, so that the previously established biochronologic dating can be now formulated on the base of the gpts dates, with a decidedly improved accuracy (fig. 20). this chronostratigraphic asset of the faunal events is also valid for the main events of the global climatic changes, which were recorded in the apennine continental sediments using the magnetic signal for processing the spectral distribution of its changes, and detecting the oscillations of the pollen percentage affecting vegetational assemblages of cooler and warmer climates. both proxies were investigated in parallel over three sequences, whose time series were constrained by a direct magnetostratigraphic zonation. in the upper valdarno, the interval 3.1÷2.64 ma showed the shift from the precessional to the obliquity cyclicity at 2.85 ma; in the valtiberina, the interval 2.8÷2.1 ma showed the same shift, but shortly later; in the san arcangelo basin of southern apennines, dated shortly before the jaramillo, the eccentricity cycle period was already established along with that of obliquity (albianelli et al., unpublished data). climatic changes in the geological system were inferred from palaeotemperature oscillations in the oceanic waters (shackleton, 1995). they consist of fre151calibration of the upper val d’arno basin ... quent fluctuations, at a rhythm of approximately 40 ky, which took place after a steady decline to cooler temperatures occurring between 3.1 ma and 2.5 ma. the 40 ky signal dominated until ca. 1.0 ma, and was followed by a marked change in amplitude and frequency with a shift to fluctuations of 100 ky and to a further decline in temperature involving major climatic changes on the continents. a marked change of climate in china was shown by deng et al. (1999) to coincide with the beginning of loess deposition, at about 2.6 ma. also magnetic stratigraphy enhanced in the loess deposits the onset of an alternating signal during wet and dry conditions with alternations of paleosols producing distinctive magnetic characters (heller et al., 1991; spassov et al., 2001). in western europe a direct influence of the climatic changes on the vegetation was evidenced by the pollen distribution with drastic changes during the late pliocene and pleistocene (zagwijn, 1974; suc et al., 1995). in the vrica stratotype area, the series yielded a pollen record representative of the central mediterranean realm (combourieu-nebout, 1993; combourieu-nebout & vergnaud-grazzini, 1991). in the northern apennines such changes were searched in the upper valdarno, where details in the vegetational associations were dated since 3.1 ma with the stratigraphic resolution of the gpts. the subtropical forest of warm-temperate climate, already established since the early pliocene, was still steadily persisting in the mid pliocene meleto clay, and gradually replaced by a conifer vegetation of cooler climate (bertini, 1994), beginning in the middle of late gauss, at 2.85 ma. this date was focused by a marked change in the spectral content of the magnetic susceptibility profile, with the amplitide of the dominant cycle at 20 ky period of the precessional index in the early pliocene drifting to the 40 ky period of the obliquity (albianelli et al., 1999; napoleone & albianelli, 2002). a similar drift was recorded by the magnetic signal in the deposits produced by the climatic changes in the subtropical africa (demenocal & bloemendal, 1995). the measured periods of the cycles were in the range of the milankovitch changes of the astronomical parameters affecting the solar radiation. it may be assumed that temperature changes in the boreal hemisphere were triggered by the insolation, and that deep ocean sediments reflected with a definite lag events which had taken place on the surface of the earth. the lag, from the observations on continental faunas and loess deposition, was possibly of the order of 100 ky, or may be even larger according to pollen and magnetic records. the villafranchian terrestrial faunas of the apennine basins were deeply influenced by climate changes at the gauss/matuyama boundary when the pliocene ice-rafting took place (shackleton et al., 1984), and at the jaramillo. in contrast, at the pliocene/pleistocene bondary their turnover was much less notable, as shown in the following faunal distribution, reconsidered after its magnetochronologic asset. the present paper discusses faunal events that took place in central and southern italy (fig. 19) during the period from nearly the onset of the late gauss, through reunion and jaramillo, up to the onset of brunhes, approximately from 3.1 ma to 0.8 ma. magnetostratigraphic calibrations made in the upper valdarno involved sequences not much younger than the end of olduvai (1.77 ma), thus not reaching 1.70 ma. then two short sections, at colle curti and cesi in the colfiorito basin and the one at oriolo in the littoral deposits of the external apennines (to be discussed at the end of this chapter), were respectively dated to the jaramillo and beginning of brunhes. most of the middle pleistocene is now being studied through one single section in the southern apennines, although with a poor faunal record. preliminary studies dated its base shortly prior to the jaramillo (sabato et al., 2002), and new detailed results extended the series into the brunhes (albianelli & napoleone, unpublished data). all the assemblages reported in the following sections will be assigned a position on the gpts, summarized in figure 20, to which a numerical date will correspond for calibration. as discussed before, the late villafranchian faunas of tasso and of the close farneta area are inferred to date in the proximity of the end olduvai, but their stratigraphic position is still drawn at a younger age, so partly maintaining the biochronologic setting. their range of uncertainty is visibly wide, at the scale of the gpts geochronology, but the faunas lacking a direct magnetostratigraphic calibration are positioned with dates in the most appropriate approximation inferred from what reported below. some faunas discussed in the next sections but not shown in figure 20 can be accordingly located with the same cautions used for the accuracy of their numerical dates, which anyhow can benefit from an improved accuracy by the new position of the faunal units, displayed in the last column on the right-hand side. 66..11 tthhee ddeeppoossiittss ooff eeaarrllyy vviillllaaffrraanncchhiiaann aaggee the earliest continental sedimentation of the apennine basins is the one of the upper valdarno, as it is enhanced by magnetostratigraphy, and marked to occur in the second half of the gauss chron, to which a middle pliocene age is correlated. the earliest deposit 152 g. napoleone et al. figure 19 – map of the main sites of faunal distribution in peninsular italy. the earliest fauna, out of the triversa site located in the western corner of the po valley and north of the area here represented, was believed to lay in the area of aulla underneath the olivola site. a general trend of more evolved faunas was recognized, moving from west towards the more easterly basins. the present magnetostratigraphic dates are reported in chapter 6 for the sites here labeled: 1, olivola; 2, mugello; 3, montopoli; 4, firenze; 5, upper valdarno, in its bulk; 6, farneta; 7, selvella; 8, pietrafitta; 9, colfiorito; 10, todi; 11, l'aquila; 12, pirro nord. 153calibration of the upper val d’arno basin ... was identified on the north-western border of the mountain belt while the intramontane basins developed in upper and lower valdarno, and sarzana. their record is based on a mammal fauna that correlates with the mn16a because of absence of equus from it as well as from the sites od western europe (e.g; gea in spain, quoted in lindsay et al., 1997), readily correlated with late gauss and early matuyama. direct calibration to the figure 20 the overall recostruction of the stratigraphic position for the main mammal sites in the northern apennines is shown in the draft assembled by ambrosetti in 1994 and reported in cita & castradori (1994, quoted in albianelli et al., 2002b), and updated for all the results discussed in the present work. the calibrated faunas (positioned by the dots) are sided by the magnetostratigraphic column with normal (black) and reversed (white) polarities; the others (not calibrated, and with the shadowed column) are correlated with the gpts of berggren et al. (1995) by a lesser tight constraint, due to the faible stratigraphic resolution of their biochronological ages. the display follows a general disposition from west to east, to which correspond the dates of each site readable on the gpts, while the faunal units grouping them in the biochronological setting are shown on the vertical scale in the other extreme. for the confidence range of the faunal units dates, see the discussion in the text. 154 g. napoleone et al. gpts of continuous long profiles in the upper valdarno clears up any biochronological uncertainty leading to different scenarios, such as those discussed by lindsay et al. (1997) for the triversa fauna in its villafranca d’asti type area. there, the lower triversa sequence was correlated with the mn15 faunal sequence and with the late gilbert chron. however, this area is out of the northern apennine range while the equivalent fauna of the upper valdarno was directly calibrated in a long magnetostratigraphic series; but the triversa fauna of the type area, with its rather rich sequence, is emphasized because it marks the onset of the villafranchian and its diversification is now estimated during a long time span which as compared with the upper and lower valdarno ones. it is noteworth to recall that the geologic setting was reappraised in great detail (carraro et al., 1995), but its stratigraphic updating by lindsay et al. (1997) seems not correlatable with the upper valdarno series. 6.1.1 the triversa sequence at 3.1-2.9 ma of the kaena/late gauss chrons the triversa sequence (mn16a) comes from several sites along the triversa river near the town of villafranca d'asti in piemonte, and is mainly characterized by its typical elements zygolophodon borsoni, anancus arvernensis, ursus minimus, and the turtle mauremys etrusca (azzaroli, 1977a). the triversa fauna at fornace rdb site is considered the oldest one, and the previous list in all alike the fauna of castelnuovo dei sabbioni is thence dated in the kaena chron, at 3.1 ma. the specimens of fornace rdb were recovered in an unknown position through a short profile of silts and silty sands in the lower part, and sands higher up. its list contains also other species, macaca florentina, castor sp., acinonyx pardinensis, tapirus arvernensis, stephanorhinus jeanvireti, procapreolus cf. cusanus, leptobos stenometopon. among several other sites, the arondelli and san paolo faunas are considered to overlay by few meters the rdb site although the species list is poorer, containing the former one with insectivores (talpa cf. minor) rodents and few carnivores. they were not measured for palaeomagnetism and are placed correlative to the upper late gauss, according to the stratigraphic inferences of azzaroli (1977a). the fornace rdb profile includes a tiny normal polarity magnetozone between the two reversed ones, i.e. a nearly 25 m outcrop with a less than 2 m thick magnetic zone of normal polarity at 12 m level. the two reversals are therefore associable to the mammoth and kaena events in the gauss chron. as a consequence we reject lindsay’s et al. (1997) assignement of the earlier triversa fauna to the gilbert chron an assignment that would make it one million years older than the same faunas in the upper and lower valdarno basins. in our interpretation, then, the triversa faunal unit stems from the gauss chron, close to and/or within the kaena event (fig. 20). the arondelli local fauna, few meters above the main triversa fauna, has not yet been found in the more easterly basins, but is most likely of gauss age as well. its age could match that of the new fauna collected in the lower valdarno (to be discussed in the next section) that has been grouped in the occasion of the magnetostratigraphic exploration of the series, downwards from the montopoli locality and is now dated to not reach 2.9 ma as a lower limit. 6.1.2 lower valdarno finds with triversa affinity, 2.8 ma the oldest finds in the apennine basins, after the upper valdarno local fauna of castelnuovo, are in the lower valdarno. the significant site is in the eastern side of the basin, at the base of the marine sedimentary cycles mentioned earlier, in chapter 2. from there, the tapir recently found and few more remains were dated as coeval with the same fauna of castelnuovo (benvenuti et al., 1995). their age was not fully resolved by the marine sequence, due to a poor biostratigraphic record, as the tentative biozonation assigned the bulk of the sequence to the globorotalia aemiliana zone, therefore with a too large range for the resolution of the present correlation. also the record of the vertebrate fauna released in the lower sequence was poor, but the only one correlatable with that of the upper valdarno, as demonstrated by the magnetostratigraphic dating. this minor faunal assemblage comes from relatively recent discoveries: firstly a canid nyctereutes megamastoides del campana was found in 1917 at the brick factory chiarugi, and then two jaws of the arvicolid vole mimomys stehlini kormos, followed by a fragmental antler of croizetoceros cf. ramosus (azzaroli, 1992). a lower molar m1 of anancus arvernensis from the piazzano farm, was dated approximately 3 ma by aminochronologic analysis (g. belluomini, 1990, personal communication to azzaroli). near the small town of ponte a elsa, the antlers of a small-sized cervid were recovered and adopted as the species holotype of pseudodama lyra (azzaroli, 1992). finally, an almost complete skeleton of tapirus arvernensis was found in the clay pit of casenuove, with other fragments (dominici et al., 1994). all these specimens may be assembled in a local fauna, the lower valdarno lmf (mn16a), confined in a short time span of emersion between two thick sequences of shallow marine facies, and supposedly at a date not much younger than that of the castelnuovo fauna. in fact, the magnetostratigraphic date of the latter is close to 3.1 ma, while in the lower valdarno the aforesaid date of ca. 3 ma was the only available indication until magnetic stratigraphy of the composite sequence was measured in the overlying marine silts and sands (albianelli et al., unpublished data). it released only one magnetozone of normal polarity, taken as the end of the gauss chron before the montopoli fauna found on top of the marine sequence, and dated at the lowermost matuyama (lindsay et al., 1980). its duration, however, could not be calculated by the magnetic cyclostratigraphy, as it was done in the santa barbara profile. the sequence was made of separate short sections, although well correlated, but not with the required accuracy for detecting the milankovitch periods used in the upper valdarno to date its duration. with an indicative rate of deposition of the marine sequence similar to that measured in the upper valdarno, and the thickness reconstructed from the various outcrops, a time span longer than 200 ky before the matuyama boundary is estimated. so, the lower valdarno fauna with affinity to the triversa faunal unit would not reach a date as old as 2.9 ma and therefore be at least 200 ky younger than the castelnuovo faunal assemblage. the affinity of the latter with the triversa fauna suggests a parallel affinity of the arondelli fauna above the fornace rdb site with the present lower valdarno fauna, based on an equivalent magnetostratigraphic date inferred for the arondelli fauna. 6.1.3 the aulla find near olivola, nw toscana, 3.1 ma (?) in the abandoned clay pit, 1 km out of the aulla town, sarzana basin (val di magra), two small cervid remains were recovered in a 5 m short outcrop (abbazzi et al., 1995). part of a right shed antler was available to inferring the presence of procapreolus cusanus; a psedodama ex gr. pardinensis-lyra was also determined. their little biochronologic resolution is even reduced by a poor preservation, which did not prevent, however, to infer an early villafranchian age. actually, this was assumed in order to replace the previous age of earliest pliocene established by presence of pollen species of a vegetation still maintaining some miocene characters. large excavations, presently made to build the new railway station of aulla, and drilling bore-holes added a 30 m thickness to the sequence, down to the basal lignite-bearing clay. they did not provide a polarity sequence, but only one reversed polarity, as it was also for the 5 m outcropping section (napoleone and albianelli, unpublished data). an expected date for this 35 m thick profile with reversed polarity would suggest a magnetization acquired in the matuyama chron, and the age of this poor record would be assigned to a time younger than the gauss chron. therefore, also this site cannot be assigned a date of the castelnuovo fauna, but quite younger than that and still fitting the very wide range of uncertainty of the biochronologic inferences. from the above discussion the reversed polarity of an early matuyama would date this site younger than 2.58 ma, most probably not reaching 2.5 ma, as it is placed at least 35 m above the onset of the magnetozone and if an average sedimentation rate is assumed close to that of the valdarno basins. 66..22 mmiiddddllee vviillllaaffrraanncchhiiaann mmaammmmaallss this mammal age was a period of scanty finds, also corresponding to a generalized time of widespread transgression on land, which reduced the continental environment. in azzaroli's (1977a) revision of villafranchian the triversa fauna is the holotype of this land mammal age and represents the early villafranchian, while montopoli represented a new stage. until the present dating of the triversa-like fauna of castelnuovo dei sabbioni and of the subsequent gaussian fauna of the lower valdarno correlated with the arondelli lmf, the time span between triversa and montopoli faunal units was considered large and marked in europe by the arrival of elephant from africa and horse from n. america. the former event is dated now earlier than 3.1 ma, witnessed by the tectonic phase producing the subsidence basins in the apennine intramontane belt, the latter by the montopoli fauna calibrated to 2.58 ma. the half a million year lag from this event to the previous one is now covered by findings of intermediate dates reported for the aforesaid faunas in the upper triversa sequence. for younger ages, the only finds are the poor fauna of todi, which indeed by magnetostratigraphy is tightened very close to the upper limit of the montopoli mammal age, with a similar lag of nearly 0.5 my, but without any intermediate finding in the apennine basins. the montopoli locality contains the richest assemblage of the few ones in western europe, among which that of senèze, dated at the reunion chron, represents the successive saint vallier faunal unit. in italy, an affinity with the fauna of montopoli (mn16b) was attributed to that of costa san giacomo (central italy) (gliozzi et al., 1997). 6.2.1 the montopoli fauna of lower valdarno, 2.58 ma it is the oldest fauna of this period (middle villafranchian), at the base of the matuyama chron, dated shortly after 2.48 ma by lindsay et al. (1980), but the beginning of the matuyama has now been corrected to 2.6 ma (see shackleton, 1995), while the updated scale by berggren et al. (1995) puts it at 2.58 ma. the fauna was collected by forsyth major (1877) near a hilltop south of montopoli, a small town in the lower valdarno, west of firenze and south of the arno river. after the detailed account by forsyth major (1877), the list of fossils was revised by azzaroli and de giuli in order to update the information in the newly created automated catalogue (cioppi et al., 1996). it is fairly rich but fossils are fragmentary: archidiskodon gromovi, anancus sp., stephanorhinus jeanvireti, equus cf. livenzovensis, pseudodama cf. lyra, croizetoceros ramosus, procapreolus cf. cusanus, pliocrocuta perrieri, nyctereutes megamastoides, acynonyx pardinensis. a similar fauna from liventsovka in southern russia, near the azov sea, was described by bajgusheva (1971; 1978; quoted in azzaroli, 2001). the relevance of the montopoli fauna as testimony of a major dispersal event in the late cenozoic was emphasized by lindsay et al. (1980). soon after azzaroli (1983) brought new attention to the problem, having linked it with the mammal fauna of the himalayan india dated by magnetostratigraphic investigation to the late pliocene and early pleistocene (azzaroli and napoleone, 1981). the faunal diversification there verified, was correlated with the late villafranchian fauna of western europe, and its major dispersals, which took place before and after the pliocene/pleistocene boundary, were emphasized (azzaroli et al., 1997) in order to place in a stratigraphic order the villafranchian faunas of the italian peninsula. with the present magnetostratigraphic record these correlations could be revised with a much finer resolution. 6.2.2 the fauna from cava toppetti near todi, umbria, 2.13 ma a poor fauna was collected at cava toppetti, sw of todi, in umbria (abbazzi et al. 1997), and comprises: stephanorhinus cf. etruscus a fragmental scapula pseudodama cf. rhenanus fragments of antlers, two damaged teeth, a hoof phalange procapreolus sp. the basal portion of an antler 155calibration of the upper val d’arno basin ... apodemus cf. dominans a right m1/ this small association is presumed to be younger than the montopoli fauna, despite its poor biochronologic resolution. the fossiliferous beds crop out in the cava toppetti clay pit exploited for the brick factory, at todi, in the ponte naia formation. the series uncomformably overlies the fosso bianco fm, which was calibrated to the latest gauss and early matuyama, and soon after the reunion (fig. 2). the fossil bearing section has not given data of its palaeomagnetism, but from the above biochronological indications it may be considered older than the olduvai chron, and therefore of late pliocene age. it was actually constrained between montopoli and olivola faunal units, whose dates are now avalaible, although the second one will be further discussed in the present work. a major argument to the previous biochronologic assignment of an age is that the olivola unit is now recognized older than 1.95 ma (by possibly 150 ky), and much younger than the reunion (2.24 ma, in the gpts calibrated by baksi, 1993, or 2.15 ma in that used by cande & kent, 1995 and adopted by berggren et al., 1995). this contradicts the geological evidence because these scanty finds are overlying, with a sequence of at least 100 ky duration, the beds with normal polarity of the reunion chron, measured in the same section, but above the major fault that affects the whole valtiberina basin. a larger time span for it would reach the olduvai, which is younger than the olivola fauna, to be discussed, in the next section. more discussion on the pollen distribution and its correlation with the upper valdarno series is made specifically with the lower fosso bianco formation (pontini et al., 2002). a possible lag between their records is detected by magnetostratigraphy and attributed to climatic differences of local origin producing a microclimate. the stratigraphic position of this fauna is visualized in figure 20 as closely before olivola, and therefore strongly confined by the olivola date of nearly 2.1 ma, which will be discussed later. this position is indeed forced against the tight limit of reunion at 2.15 ma and the main fault in between. it seems an evident case for evaluating the resolution power of both chronologies when compared to one another, the highly constraining numerical one of the gpts and the faunal unit sequence of the comparative osteology, which needs very wide margins of confidence for fixing biochronologic affinities. 66..33 llaattee vviillllaaffrraanncchhiiaann mmaammmmaallss this new mammalian age (mn17) was particularly well represented either in the upper valdarno and in the italian peninsula. in the latter, several localities were collected, among which the richest one is at pietrafitta, in umbria (gentili et al., 2000). an important result seems evident: with the present numerical dates available for this continental series, the rich fossil deposits actually exhibit a monotonous composition, because they belong to almost the same narrow range of dates. it has been stressed above, for the upper valdarno, that biodiversification was practically undetectable in the faunal assemblages of the montevarchi sequence, while in the same sediments the magnetic and pollen records clearly detected the severe changes which prepared the break at the pleistocene boundary. the present dates have in fact shortened the time span of the continental sedimentation during which the assemblages remained unchanged, as summarized in the faella collection by its stratigraphical disposition spanning over 220 ky across the olduvai (napoleone & azzaroli, 2002). another important result can be commented. it is now quite clear that the late villafranchian age comes to an end pretty soon in the upper valdarno, the first find being dated 1.99 ma and the last ones demonstrated here to be not much younger than 1.77 ma. in contrast, during last half a century the trend in dating their biochronologic ages was to rather expand the time intervals between various localities, and separate these latter in faunal units in spite of their tenuous palaeontological constraints. the “wolf-event” was actually the only biochronological date to make the divide between the middle and late villafranchian (torre et al., 2001) the example of the matassino assemblage is typical because its first recognized affinity with olivola (representing the basal pleistocene), that led to assigning both of them the same age (azzaroli, 1977a), was progressively shifted to a younger age on the statement that the next tasso faunal unit should be substantially higher up in the early pleistocene, to approach the major faunal turnover of the new age (gliozzi et al., 1997; mazzini i. et al., 2000; torre et al., 2001). such a scheme was actually the basic asset for the biochronologic history of the villafranchian, but the new data brought to light by magnetostratigraphy and reported since a decade (torre et al., 1993; 1996; albianelli et al. 1995; 1997; 2002a) have drastically changed the previous framework. these results are commented stepwise, in a chronologic order mostly inferred from indirect correlations with the gpts magnetochronology. 6.3.1 the olivola fauna of lunigiana, nw toscana, 2.1 ma a rich fauna was retrieved in the late eighteen hundreds by forsyth major (1890) from silts underlying the olivola village, which stands on a hilltop ne of aulla, the main town of the lunigiana district, nw toscana, where the sarzana basin is occupied by the val di magra valley. this will be discussed just after reporting that the fauna was collected in a site already known for a long time for its content of fossil vertebrates: it was visited in the mid eighteen hundreds by igino cocchi and by giovanni capellini, who collected some specimens which were stored in the palaeontological museums of the universities of pisa and bologna. several years later forsyth major undertook a regular excavation and obtained a large collection. most of it was taken to the palaeontological museum of firenze university, some fossils were brought to the british museum (natural history), where among others a fine facial skull of sus strozzii is now stored. fossils were transported by a stream; they are white and brittle, embedded in a pink-yellowish matrix, and as a rule are disconnected, but some articulated, partial limbs were also collected. bones were selected according to size: an elephant is represented only by a partial ulna and radius and part of the carpus; other large herbivores and carnivores are common, smaller species are rare (azzaroli, 1950). the most common species are: 156 g. napoleone et al. stephanorhinus etruscus skulls, jaws, limb bones equus stenonis skulls, jaws, limb bones sus strozzii fragmental skulls, jaws, limb bones leptobos etruscus fragmental skulls, jaws, limb bones eucladoceros dicranios olivolanus partial skulls, jaws, antlers, limb bones pseudodama nestii partial skulls, jaws, antlers, limb bones ursus etruscus partial skulls, jaws, limb bones canis etruscus skulls, jaws, limb bones pachycrocuta brevirostris a maxillary, two jaws, isolated teeth, few limb bones less common elements are: megantereon cultridens a partial skull, fragmental jaws, isolated teeth homotherium crenatidens few teeth lynx issiodorensis an incomplete skull, a maxillary, a jaw, fragments of the pelvis and limbs. these species are also represented in the montevarchi succession of the upper valdarno, with the only exception of eucladoceros dicranios, represented in the upper valdarno by a different subspecies (see below). species recorded in italy only from olivola are: procamptoceras cf. brivatense an upper tooth row gallogoral meneghinii a partial skull, the distal end of a humerus chasmaporthetes lunensis a partial skull felis lunensis (also called felis sylvestris lunensis by ficcarelli and torre, 1974, in azzaroli 1977a) a felid of the size of a common cat: a jaw, partial fore and hind limbs. the first two species occur in italy only at olivola; they also occur in france, in the middle-late pliocene. the problem of dating the olivola site, previously established to represent the base of the pleistocene, was a critical one since the initial calibration in the upper valdarno sites. its age is still lacking a direct magnetostratigraphic exploration, but inferences were made, based on the following statement (cioppi & napoleone, 2001). the matassino fauna was considered, on the biochronological basis, of the same age as olivola for the affinities between them, and then its age was moved stepwise to younger dates than olivola (e.g. azzaroli et al., 1988; gliozzi et al, 1997). separately, the faella fauna -in all alike the matassino onewas dated as old as 1.99 ma (albianelli et al. 2002; napoleone & azzaroli, 2002). the olivola must precede the pleistocene boundary, fixed at 1.796 ma in the end olduvai, by more than 200 ky. moreover, considering that in the upper valdarno the new late villafranchian fauna is retrieved from the terranuova silt and this sequence extends more than 50 ky earlier than the basal fossil find of faella, an upper limit for the olivola date might be as old as 2.05 ma and a lower limit younger than reunion, to which the senéze fauna of the st. vallier faunal unit is calibrated. a date younger than reunion is further fixed as a more recent time by the fauna of todi, already recognized quite younger than reunion but assumed older than olivola. with the biochronological considerations made before, a date of 2.1 ma with a narrow excursion (say, less than ± 50 ky) is conceivable for olivola, and this puts its date quite older than any other one reported so far. this shift to the late, and not even the latest pliocene has been pushed back since the first calibration of the matassino fauna (torre et al., 1993), when the upper valdarno faunas of the montevarchi succession were already considered quite younger than olivola. with the present magnetostratigraphic calibration, all these faunas are quite aged, as shown in the previous chapter, being dated still prior to the onset of the olduvai chron (albianelli et al., 2002a; napoleone et al., 2001b). the yellowish silt of the fossil deposit is exposed at olivola for about 1 m in thickness and is magnetized with reversed polarity: this is not in conflict with the discussion made before, but not decisive for defining a more precise date than that just inferred at 2.1 ma. 6.3.2 the recent finds from north of roma, 2.0÷1.75 ma (?) an occasional find at monte riccio, in the northern lazio district, 10 km inland from the tyrrhenian sea and 100 km n of roma, was the first locality from that area and dated after the analogies with the fauna of the upper valdarno (mazzini i. et al., 2000). in a 30 m section of very shallow marine facies, attributed to the late pliocene by the geological evidence in the area, a terrestrial fauna was deposited during a short episode of emersion. a biostratigraphically poor association is based on ostrea, clamys, pecten, etc., mostly indicating the low water depth, and a similar estimate was provided by the benthic foraminifera. an ostracod with stratigraphic meaning, cyperideis torosa, would be noticeable for its first appearence being at the beginning of the pleistocene. nonetheless, this is one of the few occasions, in the italian peninsula, to have an indication of biostratigraphic dating for a terrestrial fauna. a fairly rich assemblage overlying the marine detrital sequence is formed by the following specimens: prolagus sp. two fragmentary molars elephantidae cf. archidiskodon meridionalis some limb bones and a dental lamina sus strozzii fragmentary mandible and a metapodial hippopotamus sp. a fragment of the skull leptobos cf. leptobos etruscus two frontal bones, a metacarpal procapreolus sp. fragmentary frontal bones with the basal part of the antler eucladoceros ctenoides a basal part of an antler, some molars, a tibia fragment, a calcaneum of juvenile specimen pseudodama? metapodials, fragmentary limb bones, jugal teeth stephanorhinus cf. s. etruscus a fragmentary humerus, radius and tibia equus stenonis an almost complete mandible very similar to the holotype from the upper valdarno, a fragmentary scapula vulpes cf. vulpes alopecoides part of mandible with two molars canis etruscus a fragmentary mandible with two molars and a left hand in anatomical connection megantereon cultridens a metatarsal the range of these species spans a large interval, but their association leads to a restricted age comprising 157calibration of the upper val d’arno basin ... the olivola and tasso faunal units (mazzini i. et al., 2000). this indication led to assigning an age derived from the alleged age of the latter in the late part in the erly pleistocene, still used in the catalogue and in the most recent accounts (gliozzi et al., 1997; torre et al., 2001). but this resulted an inference very weak for the monte riccio section, as the biochronological range of the tasso fauna is actually poorly defined, and even less is the biostratigraphic timing of the profile with a generical age as pleistocene. the presumed age, at the resolution of the tasso faunal unit, was arbitrarily used in a stratigraphic meaning for its upper early pleistocene age, disregarding the indication of the only fossil there recognized with a stratigraphic meaning for a presence started since the beginning of the pleistocene. nonetheless, the affinity with the tasso fu still provides an age indication better constrained than that of a broader pleistocene given by the marine fossils of this short series, and dated with the accuracy fixed for the tasso fu by the new magnetochronologic constraints. therefore, with a tasso fu dating soon after the olduvai, its age would be in the earliest pleistocene, in a very limited range before 1.7 ma, and anyhow quite shorter than that assigned in figure 20 to the faunal unit. 6.3.3 the firenze basin, 1.8÷1.7 ma firenze lies in an old lacustrine basin which, unlike the upper valdarno, was never filled completely. scanty fossils were collected. on the right bank of the arno, in the centre of the town, some limb bones of an elephant were retrieved during excavations for the building of barracks. on the left bank, south of porta romana, in the southern outskirts of the town, an elephant tusk and few molars were collected. a fragment of a metatarsal cannon of leptobos was retrieved in a railway tunnel north of the town. a portion of the nasal bone of a rhinoceros was collected near signa, at the western end of the lacustrine basin and a fragment of a left maxillary was collected from a well near prato, in the north of the basin. these remains do not allow for a more accurate biochronological timing than the age of the latest montevarchi sediments or shortly younger (the farneta fauna?, see below). the magnetic stratigraphy is not available, due to lack of convenient outcrops, but its stratigraphic position is here assigned to an age earlier than that of the next fauna only on the basis of the biochronological indications, which were indeed recalled in several aforesaid occasions to yield a too large range of uncertainty. 6.3.4 the late villafranchian fauna of farneta, 1.7÷1.6 ma the farneta abbey is placed on a series of hills of fluviatile sands which run to the right (east) of the chiana river, a southern tributary of the arno. a rich fauna surrounds it and extends southwards until the boundary between toscana and umbria near pozzuolo. in quarries north and west of the boundary with umbria, remains of elephants and other fossils, including a beaver, were collected. a large sized subspecies of the elephant, archidiskodon meridionalis vestinus, dominates the fauna (azzaroli 1977b); the type of the species is from scoppito, west of l’aquila, central italy (fig. 19), and was described as elephas meridionalis by maccagno (1962). small sized deer are represented by the progressive species pseudodama farnetensis (azzaroli 1992) and the valdarno eucladoceros has been replaced by the more derived megaceroides obscurus, a forerunner of the middle pleistocene megaceroides verticornis. the geological setting of the area, also described by azzaroli (1992) to argue the slight differentiation of cervids in toscana (azzaroli, 1947), leads to a stratigraphic position slightly younger than the upper deposits of the montevarchi unit in the adjacent upper valdarno. the quarrying is over and not sufficiently long sequences with fresh cuts are useful for palaeomagnetic sampling. a date however could be expected close to the end olduvai, i.e. not much younger than 1.77 ma, possibly in the range of the tasso fu with the gpts; as a direct magnetostratigraphy is lacking, the biochronologic indications are partly maintained for correlation with the stratigraphic setting of the tasso unit in figure 20. the adjustments in repositioning the fossil sites are made for the ones dated by magnetostratigraphy. only the todi and olivola ages are moved because of their stringent magnetochronological evidence. the biochronological ages of the others are partly correlated with the gpts dates, but emphasizing that their shadowed columns, by the side, earlier represented the time span presumed for the extent of the sequences lacking the magnetostratigraphic calibration, and cover the minimum range of uncertainty in this indirect correlation or pseudo-calibration. 6.3.5 selvella fauna, 1.7÷1.6 ma farther south-east, in umbria, a more poorly preserved fauna was retrieved by de giuli (1986) at selvella. it includes equus cf. stenonis, pseudodama sp. (farnetensis?), a large cervid called eucladoceros cf. dicranios (possibly a megaceroides obscurus?; see azzaroli, 1953), leptobos sp., canis etruscus, lynx issiodorensis, sus sp. and an undetermined elephant. fossils are less bulky than those collected around farneta: the stream which carried them was slowing down. arkidiskodon meridionalis vestinus is poor: few limb bones. equus stenonis, a large sized eucladoceros, and a leptobos are mainly represented by limb bones; pseudodama farnetensis is also documented by fragmental antlers, carnivores are documented by a facial skull of canis etruscus and a fragmental jaw of a lynx. the age of this locality matches that of farneta, representing only a different depositional setting, more downstream; thus, the same date of the farneta fauna is assigned to it in the representation of figure 20, although in absence of magnetic stratigraphy. 6.3.6 mugello basin, 1.7÷1.6 ma sited north of firenze and in a deep depression with a more than 600 m thick pile drilled in the central basin, this was another lacustrine basin where the fossil record had been collected for a long time, from scattered sites and without notes on their position. fossils 158 g. napoleone et al. mainly come from the lignite-bearing levels, and the interfingered or overlying clays. in the latest mining operations a rhinoceros -a small skulland an archidiskodon meridionalis vestinus -a dextral femurwere recovered and kept in the museum of firenze. important recoveries in the eighteen hundreds were kept in the museums of pisa and bologna. a rather fragmental fossil assemblage of 13 species is from the sands overlying the lignite-bearing clays and represents a fauna similar to the one of farneta. it mainly includes tusks and other bones of the large sized elephant, ursus etruscus, sus strozzii, a pseudodama, fragments of a large cervid not identified specifically, a derived rhinoceros recalling those from pietrafitta (see in next section), mustela sp. and a macaque (macaca florentina), poorly represented by fragmentary remains. the short length of the sections with the fossil recoveries, and their correlation, not sufficiently accurate to allow a cyclostratigraphic determination of the time spans involved in a given sequence, prevented assigning a date to the three surveyed sites (albianelli & napoleone, unpublished data). rock magnetic properties were among the best ones for the continental sediments so far examined in the apennine basins, but unfortunately the main result was to have measured only one reversed polarity, which leads to a matuyama chron younger than olduvai. transferring the biochronological affinities into the established asset of the numerical dates, one may figure out a date still close to 1.7 ma used for the end of the montevarchi sequence, which is also a date very close to that of the farneta fu. the range of the latter is arbitrarily kept in figure 20 too wide, as presumed by the previous biochronologic assignments, and thus placed quite younger than that of tasso. the position of the mugello fauna is not drawn in figure 20. 6.3.7 some notes on the pietrafitta fauna, 1.6÷1.5 ma a very rich fauna with several elephant skeletons was collected during excavations for the extraction of lignite at pietrafitta, in umbria, south of lake trasimeno. the fauna has not been studied and only few species have been described (gentili et al. 1996, mazza et al. 1993). the species list contain: archidiskodon meridionalis vestinus, stephanorhinus hundsheimensis, equus sp., leptobos aff. vallisarni, megaloceros obscurus, pseudodama farnetensis, ursus etruscus, panthera gombaszoegensis, pannonictis nestii, macaca cf. florentina, castor plicidens, oryctolagus etruscus, microtus (allophaiomys) cf. ruffoi, microtus (allophaiomys) chalinei, mimomys pusillus, sorex sp., talpa sp. among other species, a large deer is documented by an antlered skull and several other remains, megaceroides boldrinii, named after its collector (azzaroli & mazza, 1992). the best preserved specimen is a juvenile antlered skull. there are, in addition, fragmental antlers belonging to at least seven individuals, a right jaw and some limb bones. the antlers display an exceedingly high variability, which is interpreted as evidence of a genetical instability preceding the evolution leading to m. obscurus and in the galerian to m. verticornis. for the same reasons as with the mugello fauna, the uncertainty for the dates is relatively large, and a possible date would be quite older than the reported 1.5 ma for the farneta fauna in figure 20. the short section presently outcropping has been sampled for palaeomagnetics, and its samples showed very stable directions. it recorded only one reversed polarity (albianelli & napoleone, unpublished data) presumably a matuyama date not better defined, but still not much younger than the end of the olduvai, based on the biochronological affinities with the farneta fauna. 6.3.8 the faunas from pirro nord in se italy this fauna was retrieved by de giuli and collaborators near pirro nord, in the surroundings of apricena, at the eastern foot of the mountains of the gargano promontory in the south-east of the italian peninsula. the geologic setting is devoid of a detailed stratigraphic position, while the fauna is still under study; a preliminary note was published by de giuli et al. (1986), attributing a still younger age to it, while specific aspects were also reported (mazza, 1987; mazza et al., 1993; masini & santini, 1991). the most characteristic element of the fauna is eobison, a genus of intermediate morphology between leptobos and bison, represented by a partial skull with a bulging forehead, a jaw and two rather short and massive metacarpals. the fauna, collected from several sinkholes, is rich. it includes an elephant, a rhinoceros (may be stephanorhinus), a rather slender limbed equid with stenonid features in its dentition, a pseudodama more derived than p. farnetensis, a megaceroides, sus, megantereon cf. cultridens, homotherium crenatidens, pachycrocuta brevirostris, canis arnensis, canis falconeri, ursus etruscus, vulpes cf. alopecoides, hystrix, apodemus, microtus, hypolagus, lepus, miniopterus, myotis, rhinolophus, talpa. with the lack of any stratigraphic indication sharper than the biochronological one (ficcarelli et al., 1996), the dating of this fauna, which was distinguished in a unit representing the end of the villafranchian mammal age, is positionable in a wide range of the gpts. but it is also quite likely that the next dramatic change, which will occur with the turnover at 1 ma, took place after a long sedimentation gap, due to a long tectonic activity in the apennines and/or to a generalised unfavourable state of environmental conditions for the continental deposition. therefore, a date still not much younger than 1.7 ma is conceivable, also in view of the indication deriving from the evidence discussed shortly below. meanwhile, its position is arbitrarily maintained in figure 20 at a higher stratigraphic level. 66..44 eenndd ooff tthhee vviillllaaffrraanncchhiiaann aanndd ttrraannssiittiioonn ttoo tthhee nneeww aaggee aatt tthhee jjaarraammiilllloo bboouunnddaarryy,, 11..0055 mmaa the alleged middle pleistocene following the end of the villafranchian saw the development of a large number of mammalian species and new adaptations: the large deer megaloceros and megaceroides, the heavy bovids bos, bison and ovibos. equids differentiated into a large number of species, the cold-adapted mammuthus made its appearance. the new age has been related to a major event in the pleistocene, which makes the turnover to the middle pleistocene. it is calibrated in the gpts to the jaramillo chron, so that a date for its onset is fixed at 1.05 ma. in the upper 159calibration of the upper val d’arno basin ... valdarno, the last testimony of a faunal association in the bucine fauna was classified to an age of late middle pleistocene, while in the present magnetochronologic reconstruction is dated at the base of the jaramillo or at most at the base of the brunhes. out of the upper valdarno, the beginning of this new age has the first example with the colfiorito and oriolo faunas, because they are directly calibrated by means of magnetostratigraphy to the gpts. another site of comparable age had a palaeomagnetic survey, the outstanding site of isernia with its human remains, but is not calibrated because its magnetostratigraphy yielded only one normal polarity, interpreted as an early brunhes from biochrological and anthropological inferences (sala, 1990; sala & fortelius, 1993). 6.4.1 the alleged middle pleistocene fossils from the farneta area the late villafranchian deposits of farneta described above are overlain by coarser sediments with a scanty fauna of galerian age. remains of a skull of megaceroides verticornis were retrieved from the vicinity of farneta abbey and further south, at pozzuolo and petrignano in umbria. remains of a hippopotamus were collected near farneta. here it can be recalled that, lacking a time constraint until the date of 1 ma, the time span between the farneta fauna and these remains of galerian age is cancelled by the coarser sediments just mentioned. the same case was reported in the upper valdarno where the gap between the end of the montevarchi series at nearly 1.7 ma and the new one overlying the conglomerate on both sides of the arno river bank at nearly 1.05 ma or 0.78 ma, was, on the contrary, measured by magnetic stratigraphy thus lasting 0.7 my or 1 my. therefore, a similar condition would be repeated in valdichiana after the deposits of the farneta localities. above the gravel bed, the new faunal remains would date roughly 1 my younger than last villafranchian deposits, as calibrated in the adjacent upper valdarno in the profile of cava minuto (fig. 17) succeeding the late pliocene one of faella. 6.4.2 the fauna of colle curti this fauna was recovered in the colfiorito basin, on the apennines not far east of the watershed between umbria and marche. it was palaeomagnetically dated at the onset of the jaramillo and therefore close to 1 ma, with an age calibrated to it for the emilian bio-chronostratigraphic stage (coltorti et al., 1998). the beginning of the great faunal revolution from late villafranchian to galerian is related to such an event. the fauna, still under study, is significant, represented by megaceroides verticornis and stephanorhinus cf. hundsheimensis, two typically galerian elements, with some survivors from late villafranchian: pseudodama cf. farnetensis, canis arnensis, canis cf. falconeri, ursus cf. etruscus, microtus (allophaiomys) cf. pliocaenicus and a large sized variant of hippopotamus antiquus (borselli et al., 1988; ficcarelli & mazza, 1990). its stratigraphic position is in a 12 m thick silt level, overlying a longer series of sand layers, in correspondence with the polarity change from a reversed to a normal magnetozone. the transitional characters of the colle curti assemblage are therefore peaked at the magnetic polarity transition, dated 1.05 ma in the gpts. another date at 426 ka was provided by the radiometric timing of the tephra contained in the paleosol level unconformably overlying the basin fill. 6.4.3 the fauna of cesi in the same basin of colfiorito, at cesi, few km away, a 10 m sequence of silt containing the fossil site and overlain by the same paleosol with the tephra dated 426 ka was assigned a higher stratigraphic position than the previous one at colle curti. the polarity couplet of reversed and normal directions was referred to the only possible polarity change younger than the jaramillo of colle curti (ficcarelli et al., 1997). the fauna was with more differentiated characteristics, and this led, together with the radiometric date of the overlying paleosol, to assigning the polarity chron a magnetostratigraphic date of the end matuyama, at the boundary with brunhes. a long separation between the deposits of these two colfiorito faunas, from jaramillo to brunhes, was actually introduced on the bases of such preliminary inferences rather than by firm stratigraphic markers recognized in their distant profiles. both sequences extended over ca. 10 m thick beds of massive fine sediments, capped by the paleosol layer containing the dated tephra. the date of an early brunhes was therefore tentative, expecially when compared with similar results from the oriolo fauna, reported in the next section, which in contrast supports the choice of the jaramillo date. both sites are positioned (fig. 20) according to the previous constraints but are left in that yielded by the biochronologic determination, while magnetochronology would have been undetermined between brunhes or jaramillo boundary. the fauna includes among others stephanorhinus cf. hundsheimensis, hippopotamus sp., megaceroides solhilacus, cervus elaphus, dama clactoniana, bison schoetensacki, homotherium, and an indetermined elephant (archidiskodon meridionalis vestinus ?) whose date at the onset of the brunhes chron would extend its previous range of distribution (torre et al., 1996), known so far until the jaramillo. 6.4.4 the fauna of oriolo the finds are scarse and include scanty remains of hippopotamus, rhinoceros, horse, bison and elephant in a 20 m thick section through the transitional sequence from the sand unit overlying the main blue clay formation of the external apennines. most representative are the skull of bison cf. schoetensacki at the bottom and a skull of archidiskodon meridionalis vestinus close to the top, in a reversed polarity and in a normal one, respectively. this disposition does not contradict an assigned date to the jaramillo, although the sedimentary indications suggest a more recent age, while the former was preferred because the a. meridionalis vestinus is known until the jaramillo and its extension to the brunhes would deserve a stronger support by a widespread recognition rather than the generalised age of the geologic setting. therefore, all three sites lately measured are datable in the transition to the jaramillo, which could also be 160 g. napoleone et al. the date of the bucine fauna of the upper valdarno, leading to a conclusion that no one fauna so far examined in the northern apennines would be representative of the new mammal age. this time span should be searched in the records of younger basins, as are those from the southern apennines. one example has been reported from the san arcangelo basin, already mentioned (sabato et al., 2002), and with new palaeomagnetic data which calibrate a section nearly 200 m thick, spanning from the reversed polarity before the jaramillo to the beginning of the brunhes (albianelli et al., unpublished data). in a lateral section, where the fossiliferous site with a poor fauna of micromammal species was found (masini et al., unpublished data), the measured magnetic polarity was in the brunhes, and the biochronologic indication suggested an age of this site related to an early brunhes (masini, personal communication). 77.. ccoonncclluussiioonnss magnetic stratigraphy has now dated the upper valdarno series in the gpts system, and therefore this basin results one of the oldest in age and the one of longest duration among the sequences in the intramontane basins of the italian peninsula. it spans from middle through late pliocene, up to the beginning of the pleistocene, during which two major steps of the appennine uplift brought about such extensional basins, in a time span comprised in the magnetostratigraphic framework of 1.5 my (fig. 2). the second one, in particular, produced a long gap in the lacustrine sedimentary record, dated to last more than 0.7 my. the first interruption, instead affected the faunal and pollen records, which registered the main climatic events of the glacial pliocene. in fact, from the magnetochronological criteria, the bases were developed for a new concept in dating faunal complexes, which provided facts of a tangible and substantial renovation (lindsay, 2001). by themselves, they warrant a radical revision of what was established in more than one and a half centuries, until azzaroli (1977a) decidedly pointed to the stratigraphical significance of the historical content inherent in the museological collection of fossil vertebrate faunas of the upper valdarno, with which the history of the museum of firenze was started. the awareness of the lack of basic chronological data for all ancient collections brought us to look for new ways of confering a more significant dating to the biochronological criterion which had been protracted since the first results of the comparative osteology of cuvier (1824). through inductive ways, comparing what had already been established with magnetostratigraphic criteria of dating continental sedimentary sequences, the mammal faunas of most apennine basins may be reasonably dated with a highly improved accuracy, assigning them the ages of the pliocene and pleistocene biostratigraphic record. also classical vertebrate fossils of the upper valdarno collections in the museum of firenze were dated with a resolution of few thousand years out of an age of nearly 2 ma, due to the direct calibration of their sites within the magnetostratigraphic series of 2.5 my there established. for the geological setting of the sedimentary series, the newest data provided by dating the time span between major events, such as the duration of the upheaval pulses and breaks of sedimentation, put fundamental steps for re-defining the history of the basin fill. the sedimentation started at 3.3 ma in the mammoth magnetochron, but the bulk of the lake deposits is dated after the short episode of the lignite seam (may be shorter than 3.13 to 3.08 ma) across the boundary of 3.11 ma for the kaena chron. the thick meleto-clay pile of silts lasted until 60 ky before the gauss-matuyama boundary of 2.58 ma, and was replaced by sand deposits (san donato sands) rapidly filling the basin. the g/m boundary was recorded during a subaerial deposition (rena bianca sands) when a condensed series of sand accumulated until shortly before the reunion chron at 2.15 ma. this dating is the most recent result, first reported in this work, and the implications need to be discussed with great attention. after this interruption (at 2.64 ma) a lacustrine-fluviatile regime was restored with the montevarchi sequence shortly after 2.15 ma. the new silty sediments have been recently found in contact with the sand, and therefore the reunion was immediately followed by the reversed matuyama polarity. the first mammal fauna is recovered in layer beds dated 1.99 ma, after which its blooming is recorded thoughout 220 ky and with resolutions of very high accuracy, while several important facts occur at the same time and are now dated in the upper valdarno series. the main events coeval with the faunal record are the two magnetostratigraphic boundaries between gauss and matuyama and the end-olduvai. the first calibrates to the gpts the chronostratigraphic boundaries of the middle and late pliocene, and the second the end of pliocene and the beginnig of the quaternary. this makes the upper valdarno continental sequence the reference series for correlating the apennine continental basins on the bases of events on the global scale which produce the main changes in the geologic system. two main climatic changes were documented in the geologic system. one was the temperature oscillations on a trend of decreasing values, observed in the oceanic record by the oxygen isotope ratios (summarized in shackleton et al., 1984). the other one observed in the continental areas was given by the pollen percentage changes, reproducing vegetational assemblages of wet/temperate forest alternating with those from herbs and sprouts of a dry/cold vegetation (summarized in zagwijn, 1974; leroy & seret, 1992). the former took place as a decreasing temperarture marked by the increasing of the absolute values of the oxygen ratios, which began to cyclically oscillate with the 41 ky period, as the obliquity atronomical parameter, while approaching the boundary between middle and late pliocene. its calibration has been updated by shackleton (1995). the latter confirmed the trend of decreasing temperatures by remarking a decrease in pollen percentage of the arboreal plants, from a forest vegetation of a warm and wet climate towards a cooler one, leading then to an oscillating abundance of forest and herb pollen sporomorphs. this condition spinned up in the olduvai, when it drastically jumped to nearly 90% of the steppe vegetation representative herbs dominated by artemisia, while in the ocean the oscillating ratio moved to periods of 100 ky, the short eccentricity cycle. the magnetic signal was capable of detecting both changes in the milankovian periodicities, acting as another proxy independently to the previous ones, and to date very accura161calibration of the upper val d’arno basin ... tely their occurrences. the earlier one was enhanced by the onset of the obliquity cycle taking place at 2.85 ma a date representing the initial conditions leading to the pliocene glacial/interglacial alternation systemand overprinting the precessional one which was prevailing before. the second one by calibrating the p/p boundary in the continental deposits where the highest percentage of herbs pollen was recorded in correspondence to the level beds just preceding the pleistocene by few tens of ky. this is another date of critical relevance because its recording in the marine series of vrica, southern italy, decidedly contributed to fixing there the ‘golden spike’ for the pleistocene boundary stratotype, “just before the end of the olduvai”, at 1.796 ma (zijderveld et al., 1991). in these ages accurately dated, also the upper valdarno faunas were all dated at high resolution. the range spanned from 50 ky to 2 ky, according to the degree of accuracy for their positions reported with the recovery, from the ones only located in a broad area or stratigraphic level to the ones with detailed positions, given the present magnetostratigraphical framework. it begins in the gauss chron and extends throughout the olduvai (1.77ma), thus establishing an essentially continuous magnetostratigraphic reconstruction of the continental series, after which an interruption of nearly 1 my was documented in the basin fill. more outcrops of these continental deposits may be uncovered by excavations for industrial purposes, and thence more data would be added. in the prospect of new results, some of the closest ones may be suggested as an outlook. improving the dates of the museum collections. high resolution dating of the upper valdarno fauna from the main collections in the museum of firenze was made at ± 2 ky for the fossil sites with accurate positions, and at ± 50 ky for those reported in the catalogue without indication of a precise position. to this group belong almost 75% of the upper valdarno collections, which will have in the present magnotochronologic framework the best reference for reconsidering their broad datings of specimens labeled so far as simply pliocene or pleistocene. with such a resolution, a review of information available in the automated catalogue is highly recommended; as a conclusion of the present work, the ages of most of these faunas would shift from pleistocene to the last 300 ky of the pliocene. the first dates were already assigned, and their numerical uncertainties were close to ± 10 ky; this resolution seems viable for the specimens of several collections. a second point would deal with the pollen events, as changes in their percentages can be dated with the same accuracy reached in the mammal fauna, so that subtle changes can be ordered in time series in order to analyse the climatic changes. the main global events were already identified in the upper valdarno record: refinements at a higher order can detect minor changes between close areas, at the scale of microclimates, such as that already tested in the apennine basins, where differential upliftings may have affected their paleoenvironments. the case of a short diachronism, measured between upper valdarno and valtiberina pollen records at the gauss/matuyama boundary, can be extended to other basins to reconstruct the history of the climatic changes in the italian peninsula. a further point would focus attention on the correlation of the marine series of the italian peninsula with the calibrated upper valdarno series, by reversing the prospects for a finer resolution. the continental sequences are now very well dated series, with a time resolution extremely high and able to improve, for most sequences through the apennines, that of the biozonation, which is in contrast rather poor in these critical ages from pliocene to pleistocene. the stages around the boundary, best represented in the italian sequences, may have a number of detailed tests dealing with dated sequences to reconstruct the comprehensive sedimentary geology, produced after nearly a century since that compiled by gignoux. the present case of the mid and late pliocene sequence of the marchean pelites calibrated to the gpts (this volume) demonstrates the role represented by the upper valdarno magnetochronology as a reference sequence. a direct correlation between these series, documenting the upheaval of the apennine range on both sides of the watershed, is producing dates of various episodes of its tectonic activity. the conclusive figure 20 shows the faunal distribution of the main portion of the classical sites and few recent ones that have been calibrated to magnetochronology. some crucial faunal units remain to be calibrated, as olivola and tasso. for both of them only a short continuous sequence can be measured, and this will add little information. more important would be to calibrate the interval from the olduvai to jaramillo which includes the faunal units of farneta and pirro. they are now positioned in a more appropriate relationship with the gpts reference than previously attempted without a close magnetostratigraphic reference, such as the present one of the upper valdarno. a new accurate timing can be used for reporting on finds which will be recovered with stratigraphic indication, and from magnetochronology trying to set up the various evidences to reconstruct for them a biochronologic history with stratigraphic criteria. aacckknnoowwlleeddggmmeennttss the present work benefited during several years from the help of numerous scientists and organizations, in the field recognition on pit sections. new fossil recoveries provided fundamental markers for the biochronologic asset of the late villafranchian, leading to a reconstruction of a magnetostratigraphic profile where a detailed positioning of their sites dated the ages directly to the gpts. the owners of the pits recalled in this work are deeply aknowledged for letting us survey any available outcrop, especially the brothers del buffa who opened new trenches at matassino and poggio rosso for recovering fossil remains and sampling fresh outcrops for magnetostratigraphy. several organizations provided cores from bore-hole drilling. the administrators of the terranuova bracciolini township put to our disposal two cores from the hilltop near the casa frata site, which yielded the tasso sand and oreno sand in the montevarchi series. the administrators of the montevarchi township let us sample two cores drilled in the arno bed, which hel162 g. napoleone et al. ped to extend downwards the profile of the montevarchi series. two more were made available in the rena bianca by the owners of the pit, and their few limy beds confirmed the presence of the gauss/matuyama boundary at its bottom. the enterprise people in charge (ing. bianchini) provided us with two cores drilled in the aulla railway station that supported the idea of a younger date than gauss for the aulla site. the continuous financial support from both our organizations, the museum and the department of the firenze university, is deeply aknowledged for helping in the operations of recovering fossil material and surveying for sections eligible for pollen and 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(1960) aspects of the pliocene and early pleistocene vegetation in the netherlands. mededelingen van de geologische stichting, ser. c, 3 (5): 1-78. zagwijn w.h. (1974) the plio-pleistocene boundary in western and southern europe. boreas, 3: 75-97. zijderveld j.d.a., hilgen f.j., langereis c.g., verhallen p.j.j.m. & zachariasse w.j., 1991 integrated magnetostratigraphy and biostratigraphy of the upper pliocene lower pleistocene from the monte singa and crotone areas in calabria, italy. earth planet. sci. lett., 110077, 697-714. 166 g. napoleone et al. impaginato atti 11.. iinnttrroodduuzziioonnee il suolo, trovandosi all'interfaccia fra litosfera e biosfera, risente profondamente dei processi che alterano l'equilibrio di entrambe, registrandone gli effetti sotto forma di figure permanenti, analizzabili e riconoscibili mediante determinate tecniche analitiche. pertanto, esso può divenire un importante indicatore delle variazioni ambientali che sono avvenute a partire dal pliocene superiore, quando l’area mediterranea fu interessata da fluttuazioni climatiche che produssero una alternanza tra condizioni subtropicali e climi oceanici (cremaschi, 1992). in particolare, per quanto riguarda l’area prealpina, un classico esempio di questa situazione, è dato dalle terre rosse1, ossia paleosuoli evolutisi su substrati calcarei in condizioni subtropicali mediterranee (pre-glaciali o interglaciali), successivamente troncati da processi connessi al deterioramento climatico durante le diverse fasi glaciali del pleistocene. tali paleosuoli, ove si trovino legati a superfici topografiche il quaternario italian journal of quaternary sciences 1155(1), 2002, 131-140 ppaalleeoossuuoollii ttiippoo tteerrrraa rroossssaa aall mmaarrggiinnee pprreeaallppiinnoo.. iill ccaassoo ddii ssttuuddiioo ddeell mmoonnttee ccaassttoo ((vvaall ssaabbbbiiaa - bbrreesscciiaa)) ll.. ttrroommbbiinnoo11 && ff.. ffeerrrraarroo22 1cnr centro studio geodinamica alpina quaternaria via mangiagalli 34, 20133 milano 2università degli studi di milano dipartimento di scienze della terra, via mangiagalli 34, 20133 milano riassunto paleosuoli tipo terra rossa al margine prealpino. il caso di studio del monte casto (val sabbia brescia). l’area della val sabbia, nel suo tratto prealpino, è caratterizzata dalla presenza di una paleosuperficie su cui si sviluppano suoli di tipo terra rossa, spesso costituiti da coltri colluviate e, solo in particolari situazioni, conservati in posto. il profilo in esame è stato identificato e descritto sulle pendici del monte casto, un piccolo rilievo calcareo che raggiunge i 400 m di quota. il profilo è costituito da due unità pedologiche distinte che vanno a formare un profilo composito: l’unità profonda è un paleosuolo fersiallitico in posto, tipo terra rossa, mentre quella superficiale mostra le caratteristiche di una successione di più coltri di loess pedogenizzate. le due unità sono state distinte in base alle loro caratteristiche micromorfologiche, chimiche e fisiche, e attraverso parametri e indici che ne hanno evidenziato il diverso grado di sviluppo morfologico e di espressione della pedogenesi: conseguenze, queste ultime, di un profondo cambiamento ambientale che ha interessato l’area in esame durante la sua storia geologica più recente. abstract terra rossa paleosols on the prealpine border. the study case of mount casto (val sabbia, brescia northern italy). the prealpine reach of the val sabbia is characterised by the presence of a paleosurface strictly associated to the development of terra rossa type soils. they are often constituted by colluviated blankets of soil material and, only in particular situations, preserved in place. the described soil profile has been identified on the slopes of mount casto (a limestone plateau 400 m high). the profile is composed of two different pedologic units: the deeper one is a terra rossa fersiallitic paleosol in place, while the upper one is a soil developed from some loess blankets. the two units can be identified on the basis of their micromorphological, chemical and physical characteristics and, above all, using indexes and parameters enhancing their different degree of morphological development and of pedogenetic expression; the latter due to a paleoenvironmental change affecting the study area during its recent geological history. parole chiave: terra rossa, paleosuolo, micromorfologia del suolo, analisi elementi maggiori, italia settentrionale. key-words: terra rossa, paleosol, soil micromorphology, major elements analysis, northern italy. 1 non potendo citare in maniera adeguata oltre 150 anni di dibattito scientifico sulla terra rossa (in italiano nel testo zippe, 1853), per quanto riguarda la definizione di terra rossa si rimanda a una recente sintesi sui suoli rossi mediterranei di yaalon (1997), secondo cui il termine terra rossa viene utilizzato più o meno rigorosamente, per indicare i suoli rossi superficiali o poco profondi, che si sviluppano sui calcari in area mediterranea. stabili e non siano sepolti da una coltre di sedimenti sufficientemente spessa da isolarli definitivamente dalla superficie, sono soggetti a fenomeni pedogenetici in equilibrio con il clima attuale ed estranei alle prime fasi del loro sviluppo (cremaschi, 1987). 22.. mmaatteerriiaallii ee mmeettooddii la descrizione di campagna del profilo è stata effettuata attenendosi agli schemi suggeriti da hodgson (1976). il colore dei vari orizzonti e di eventuali screziature è stato determinato utilizzando le tavole munsell ® (1994). la designazione degli orizzonti è stata scelta in base alle keys to soil taxonomy (soil survey staff, 1990). i campioni per le analisi sono stati prelevati sia come indisturbati, sia per le analisi quantitative. le analisi pedologiche di routine sono state svolte seguendo i criteri generali proposti da avery e bascomb (1974) e da gale e hoare (1991). le analisi granulometriche sono state condotte per vagliatura e aerometria. la determinazione quantitativa del ferro estraibile ha previsto l’impiego di soluzioni di ditionito citrato, di ammonio ossalato e di sodio pirofosfato. la separazione dei minerali pesanti è stata effettuata su materiale di granulometria compresa tra 63 µm e 180 µm, preventivamente decarbonatato e deferrificato, utilizzando, come liquido pesante, il metatungstato di sodio, preparato a densità 2.9 g/cm3. per l’analisi geochimica degli elementi maggiori sono state selezionate le frazioni granulometriche più fini, precisamente: limo grossolano (coarse 63 µm 31.2 µm), limo medio (medium 31.2 µm 11 µm), limo fine + argilla (fine inferiori a 11 µm). la dissoluzione del substrato carbonatico, campionato alla base del profilo è avvenuta per immersione in bagno di acido acetico (99-100%) per oltre 2 mesi. sui campioni così preparati è stata condotta un’analisi geochimica attraverso la spettrometria per fluorescenza ai raggi x e spettrofotometria ad assorbimento atomico, al fine di determinare la composizione percentuale degli ossidi degli elementi maggiori e in parti per milione dello zirconio. per quanto riguarda la descrizione micromorfologica, le osservazioni sono state condotte secondo i canoni proposti nel handbook for soil thin section description (bullock et al., 1985). talora, nel corso della discussione è stata parzialmente utilizzata la terminologia del sistema descrittivo proposto da brewer (1964). 33.. iinnqquuaaddrraammeennttoo ggeenneerraallee il monte casto (fig. 1) è un piccolo rilievo che raggiunge i 400 m di quota, costituito da calcare della “corna”, ossia calcare compatto, di colore bianco avorio, giallo grigio, stratificato con strati potenti, a volte indistinti, del triassico superiore giurassico inferiore (definizione di curioni, 1877). la sommità del monte casto, come quella di altri rilievi presenti nell’area, è interessata dalla presenza di 132 fig. 1 carta topografica dell’area e localizzazione del profilo. topographic map and profile location. l. trombino & f. ferraro superfici a debole energia di rilievo: dal punto di vista geomorfologico esse sono i lembi di un penepiano tardo terziario, smantellato a seguito di fenomeni tettonici (chardon, 1975). su una di tale paleosuperficie si sviluppa un paleosuolo di tipo terra rossa (chardon, 1975), costituito da coltri sottili e/o colluviate, solo in particolari situazioni conservato in posto per spessori superiori al metro; spesso la terra rossa risulta coperta da depositi loessici di spessore variabile. per quanto riguarda l’evoluzione quaternaria della val sabbia, essa risulta essere stata interessata da varie fasi di espansione glaciale: riferendosi alla interpretazione fornita da chardon (1975), durante la sua massima avanzata il ghiacciaio della val sabbia sarebbe giunto fino all’altezza di barghe (pochi chilometri a monte dell’area studiata), mentre autori precedenti, quali venzo (1965), identificano depositi morenici anche più a valle del sito, nella zona di clibbio. 44.. ccaarraatttteerriizzzzaazziioonnee ddeell pprrooffiilloo 44..11.. ddeessccrriizziioonnee il profilo è stato descritto sulla parete di una cava abbandonata, che incide il versante nord occidentale del rilievo, non lontano dalla sua sommità. la superficie di campagna si trova ad una quota di 370 m s.l.m. e la copertura vegetale è essenzialmente costituita da robinia pseudoacacia. gli orizzonti identificati sono (fig. 2): o 0 20 cm, lettiera e orizzonte organico bw1 20 45 cm, 7.5 yr 6/6 (giallo rossastro), franco limoso argilloso, aggregazione poliedrica angolare minuta debolmente sviluppata, poliedri moderatamente deboli, presenza di un livello organico nei pressi del limite superiore, limite inferiore diffuso con bw2 45 100 cm, 7.5 yr 5/6 (giallo rossastro), come il precedente, eccetto aggregazione moderatamente sviluppata, rari rivestimenti di argilla sulla superficie dei poliedri, presenza di aggregati subarrotondati di materiale argilloso, limite graduale con 2bt1 100 135 cm, 5 yr 5/6 (rosso giallastro), franco argilloso, aggregazione poliedrica angolare fortemente sviluppata, poliedri resistenti, presenza di rivestimenti di argilla e di noduli e rivestimenti di fe-mn, limite diffuso con 2bt2 135 200 cm, 5 yr 5/8 (rosso giallastro), come il precedente eccetto argilloso, limite chiaro e irregolare con il substrato. 44..22.. ggrraannuulloommeettrriiee le curve granulometriche cumulative (fig. 3) consentono una precisa caratterizzazione degli orizzonti del profilo. in particolare, le curve degli orizzonti bw1 e bw2 mostrano un andamento che ricade nel campo compreso tra la curva del loess fresco e quella del loess alterato, queste ultime costruite da cremaschi (1987) sulla base di 70 campioni prelevati ai margini prealpino ed appenninico. per quanto riguarda gli orizzonti 2bt1 e 2bt2, l’argilla diviene la frazione granulometrica dominante; nell’orizzonte 2bt1 anche il contenuto in sabbia fine e molto fine non è trascurabile. 44..33.. mmiiccrroommoorrffoollooggiiaa in sezione sottile l’orizzonte bw1 è caratterizzato da aggregati poliedrici, separati da numerosi vuoti planari (fig. 4/a). la massa di fondo è costituita da grani di 133 fig. 2 il profilo del monte casto. mount casto profile. quarzo e lamelle di mica delle dimensioni massime rispettivamente della sabbia media e della sabbia fine. la frazione fine è costituita da una massa bruno giallastra, da nebulosa a maculata, costituita da argilla e grani minerali della dimensione del limo, questi ultimi inducono una b-fabric cristallitica. nella parte superiore della sezione sottile sono presenti resti vegetali solo parzialmente decomposti (fig. 4/b), mescolati ad aggregati granulari di piccole dimensioni. infine, per quanto riguarda le figure pedologiche, esse sono costituite essenzialmente da noduli e impregnazioni amorfe di ferro manganese. da un punto di vista micromorfologico, l’orizzonte bw2 è abbastanza simile al bw1: la microstruttura è sostanzialmente identica, così come sono corrispondenti le caratteristiche mineralogiche della frazione fine e grossolana, ad esclusione della presenza di alcuni frammenti subarrotondati di selce con dimensioni superiori ai 2 mm, di probabile provenienza esterna. i resti vegetali sono assenti, mentre sono stati descritti aggregati subarrotondati di argilla rossastra, interpretabili come pedorelitti (brewer, 1964 fig. 4/c). infine, per quanto riguarda le figure pedologiche, oltre a quelle amorfe, sono presenti rari frammenti arrotondati di argilla birifrangente (papulae, brewer, 1964 fig. 4/d). l’orizzonte 2bt1 si differenzia molto bene da quelli descritti in precedenza. la sua massa di fondo è caratterizzata dalla presenza di aggregati poliedrici separati da vuoti planari (fig. 4/e): lo stesso tipo di vuoti, ma più sottili, disloca ulteriormente gli stessi poliedri. la frazione grossolana è costituita da scarsi grani di quarzo e scaglie di mica, con rari frammenti di selce. la frazione fine è costituita da una massa rossa di argilla e ossidi di ferro, opaca, a b-fabric da maculata a striata (fig. 4/f). le figure pedologiche tessiturali sono costituite da rivestimenti di argilla rosso giallastri, mentre quelle amorfe da noduli di ferro manganese della dimensione massima della sabbia grossolana. paleosuoli tipo terra rossa ... l’orizzonte 2bt2 mostra le stesse caratteristiche micropedologiche del precedente, eccezion fatta per un minore contenuto in costituenti minerali grossolani. per una descrizione più dettagliata delle sezioni sottili si rimanda all’appendice. 44..44.. aannaalliissii cchhiimmiiccaa i risultati ottenuti dall’analisi degli elementi maggiori e dello zirconio (tab. 1), condotti sulle frazioni granulometriche limose e argillosa dei principali orizzonti del profilo e sul residuo insolubile prodotto per dissoluzione dei carbonati del substrato in acido acetico, permettono una ulteriore caratterizzazione delle entità pedogenetiche che costituiscono il profilo del monte casto. una prima osservazione riguarda la differenza esistente tra la composizione della coppia di orizzonti bw1 bw2 rispetto al 2bt1, quest’ultimo campionato verso il suo limite inferiore, in modo da essere rappresentativo dell’intera porzione profonda del profilo; l’orizzonte 2bt1, infatti, mostra un tenore in silicio mediamente più basso, un contenuto in alluminio e ferro superiore, ed un moderato quantitativo di calcio. d’altro canto, sempre dal punto di vista chimico, il materiale (o i materiali) da cui si è sviluppato il profilo non sembra essere corrispondente al residuo insolubile della dissoluzione del calcare: quest’ultimo, infatti risulta molto più ricco in silice (resistente all’alterazione) rispetto agli ossidi degli altri elementi chimici (cfr. macleod, 1980; olson et al., 1980; frolking et al., 1983; vanmechelen et al., 1993). alla luce di questa 134 fig. 3 curve granulometriche cumulative degli orizzonti del profilo, confrontate con le curve teoriche del loess fresco ed alterato (modificato da cremaschi, 1987). grain size cumulative curves of the profile horizons in comparison with the fresh loess and weathered loess curves (modified from cremaschi, 1987). ssiioo22 aall22oo33 ffee22oo22 mmnnoo ttiioo22 pp22oo55 mmggoo nnaa22oo ccaaoo kk22oo zzrroo22 bb11 - cc 69.00 13.29 3.96 0.08 2.47 0.04 0.47 1.12 0.17 2.06 351 bb11 - mm 66.02 15.66 4.54 0.02 2.63 0.06 0.42 0.91 0.53 2.60 583 bb11 - ff 47.51 24.66 7.88 0.09 2.57 0.17 1.14 0.30 0.37 2.46 431 bb22 - cc 63.50 16.79 4.91 0.10 2.53 0.02 0.55 1.75 0.18 2.49 376 bb22 - mm 60.35 18.45 5.65 0.00 2.61 0.04 0.54 0.73 0.37 2.62 518 bb22 - ff 49.68 23.93 7.65 0.08 2.49 0.16 1.11 0.29 0.44 2.38 446 22bbtt11 - cc 50.10 22.51 8.52 0.06 2.53 0.09 1.08 0.62 0.28 2.21 334 22bbtt11 - mm 54.04 20.43 7.29 0.09 2.58 0.06 1.03 0.61 0.85 2.26 353 22bbtt11 - ff 46.45 23.97 7.57 0.10 2.57 0.10 1.51 1.16 0.66 2.94 315 rreessiidduuoo 67.62 7.39 2.26 0.02 1.75 0.04 0.15 0.14 0.39 0.45 168 tab. 1 composizione elementale degli orizzonti: valori espressi in percentuale eccetto zro 2 in ppm, h2o non mostrata (c = coarse; m = medium; f = fine). elemental composition of the horizons: values in percentage, zro2 in ppm, h 20 not showed (c = coarse; m = medium; f = fine). l. trombino & f. ferraro mancata corrispondenza chimica tra orizzonti superficiali e orizzonte profondo, e tra quest’ultimo ed il residuo insolubile, è possibile ipotizzare che l’intero profilo sia stato interessato da apporti di materiale alloctono, in quantità, tempi diversi e proveniente da più sorgenti. 44..55.. aannaalliissii ddeeii mmiinneerraallii ppeessaannttii la determinazione dell’assemblaggio dei minerali pesanti fornisce un elemento di differenziazione tra le due porzioni del profilo, sia da un punto di vista mineralogico, sia per quanto riguarda il livello di alterazione raggiunto (tab. 2). la coppia di orizzonti bw1 e bw2 mostra una composizione mineralogica drasticamente dominata dagli anfiboli (59% e 45%) che, aggiunti ai pirosseni e agli epidoti, portano il totale dei minerali poco resistenti all’alterazione al 75% (bw1) e al 63% (bw2). le specie mineralogiche più stabili (zircone, tormalina e rutilo), al contrario, presentano un contenuto del 7% circa per entrambi gli orizzonti. la prima coppia di orizzonti è anche caratterizzata dalla presenza esclusiva di cianite e clorite. la situazione cambia nettamente con l’orizzonte 2bt1, che mostra un contenuto in anfiboli pari al 25%, un totale di minerali poco stabili dell’ordine del 52% ed un quantitativo di zircone, rutilo e tormalina più che doppio rispetto agli orizzonti precedenti. dunque, due differenti mineralogie si manifestano nel medesimo profilo, con una alterazione crescente nel senso della profondità. infatti l’orizzonte bw2 risulta lievemente più alterato del soprastante bw1, mentre l’orizzonte 2bt1 è più alterato di entrambi i precedenti. 55.. ggllii iinnddiiccii ccaallccoollaattii i dati ricavati dalle descrizioni e dalle analisi condotte sui singoli orizzonti possono essere utilizzati, oltre che per un confronto diretto tra i singoli parametri, 135 a b d f c e fig. 4 il profilo del monte casto in sezione sottile: a) orizzonte bw1, massa di fondo (ppl 16x); b) orizzonte bw1, resti vegetali (ppl 25x); c) orizzonte bw2, pedorelitto (ppl 25x); d) orizzonte bw2, papula (xpl 400x); e) orizzonte 2bt1, massa di fondo (ppl 25x); f) orizzonte 2bt1, massa di fondo (xpl 25x). mount casto profile in thin section: a) horizon bw1, groundmass (ppl 16x); b) horizon bw1, vegetal fragments (ppl 25x); c) horizon bw2, pedorelict (ppl 25x); d) horizon bw2, papula (xpl 400x); e) horizon 2bt1, groundmass (ppl 25x); f) horizon 2bt1, groundmass (xpl 25x). paleosuoli tipo terra rossa ... orizzonti dell’unità profonda rispetto a quelli superficiali, per i quali il grado di arrossamento è moderato (fig. 6). 55..33.. iinnddiiccee ddeell ffeerrrroo aattttiivvoo l’indice del ferro attivo, calcolato secondo rhodes e sutton (1978) e secondo arduino et al. (1984) mostra i seguenti valori: oorriizzzzoonnttee rrhhooddeess ee ssuuttttoonn aarrdduuiinnoo eett aall.. bw1 0.84 7.63 bw2 0.82 9.52 2bt1 0.73 15.19 2bt2 0.71 16.67 anche per una elaborazione più complessa, attraverso la determinazione di appropriati indici che forniscono ulteriori informazioni sullo stato di evoluzione dei suoli. 55..11.. uunniiffoorrmmiittàà ddeell ppaarreenntt mmaatteerriiaall la valutazione di uniformità del parent material è lo strumento “quantitativo” per identificare le principali discontinuità che interessano il profilo (per una sintesi su questo argomento si rimanda a vidic, 1994). a tale scopo viene utilizzato il confronto dei rapporti tessiturali, chimici e mineralogici degli orizzonti del suolo (fig. 5). il primo parametro utilizzato in questa sede è il rapporto tra il contenuto in limo e quello in sabbia dei vari campioni (busacca e singer, 1989). i risultati ottenuti mostrano una variazione di tale rapporto tra l’orizzonte 2bt1 e la parte superiore del profilo. infatti, gli orizzonti bw1 e bw2 (rappresentati graficamente fuori scala) hanno un indice pari a 5.60 e 4.16 rispettivamente, mentre il 2bt1 raggiunge appena l’1.23. la lieve differenza esistente tra i due orizzonti bw sembra dipendere dalla maggiore alterazione di bw2. il primo dei parametri chimici utilizzati è la distribuzione del titanio all’interno del profilo (brewer, 1964). data la costanza dei valori misurati per questo elemento, tale indice non fornisce nessuna informazione sulla presenza di discontinuità, anzi sembrerebbe indicare una sostanziale uniformità del profilo. al contrario, gli altri indici chimici utilizzati (busacca e singer, 1989) sono indicativi della disomogeneità esistente tra l’orizzonte 2bt1 e quelli soprastanti. sia il rapporto calcio / zirconio, sia quello ferro / zirconio presentano infatti una brusco incremento in corrispondenza di tale orizzonte. questo andamento pare condizionato da variazioni che interessano tutti e tre gli elementi considerati, ovviamente con intensità e segno che sono specifiche. infine, anche gli indici mineralogici confermano la separazione tra l’orizzonte 2bt1 e la porzione soprastante del profilo: per quest’ultimo orizzonte infatti, gli indici calcolati secondo brewer2 (1964) e cremaschi3 (1978) mostrano valori tre quattro volte superiori a quelli degli orizzonti bw1 e bw2. è dunque possibile concludere che il profilo del monte casto sia interessato da una disomogeneità chimica e mineralogica, condizionata quindi da una diversa litologia nel parent material, coincidente con il limite superiore dell’orizzonte 2bt1, che per altro, corrisponde a una discontinuità nell’organizzazione macro e microscopica del profilo. 55..22 iinnddiiccee ddii aarrrroossssaammeennttoo l’indice di arrossamento (torrent et al., 1980) riferito al profilo del monte casto evidenzia la maggiore rubefazione degli 136 2 zircone + tormalina –––––––––––––––– prosseni + anfiboli 3 zircone + tormalina + ossidi di titanio ––––––––––––––––––––––––––––– pirosseni + anfiboli + epidoti bb11 bb22 22bbtt11 ttrraassppaarreennttii 80.5 61.7 69.4 ooppaacchhii 19.5 38.3 30.6 zziirrccoonnee 1.9 4.7 7.9 ttoorrmmaalliinnaa 5.1 0.7 4.6 rruuttiilloo 0.0 1.3 2.6 ppiirroosssseennii 4.5 6.0 5.9 aannffiibboollii 58.6 44.7 25.0 eeppiiddoottii 11.5 12.0 21.1 ggrraannaattii 5.1 7.3 13.2 ssttaauurroolliittee 1.9 2.7 3.9 ssffeennee 0.6 1.3 4.6 cciiaanniittee 1.3 4.0 0.0 cclloorriittee 2.5 2.7 0.0 bbaarriittee 0.6 1.3 2.0 aallttrrii 0.0 1.3 0.7 aalltteerraattii 5.7 10.0 8.6 tab. 2 assemblaggio dei minerali pesanti del profilo del monte casto (valori espressi in percentuale). heavy minerals composition of mount casto profile (values in percentage). fig. 5 valutazione di uniformità del parent material del profilo del monte casto [rapporto limo / sabbia da busacca e singer (1989); contenuto in tio2 da brewer (1964); rapporti cao / zro2 e fe2o3 / zro2 da busacca e singer (1989); indici mineralogici da brewer (1964) e cremaschi (1978)]. parent material uniformity of mount casto profile [silt / sand ratio, from busacca and singer (1989); tio2 content, from brewer (1964); cao / zro2 and fe2o3 / zro2 ratios, from busacca and singer (1989); mineralogical indexes from brewer (1964) and from cremaschi (1978)]. l. trombino & f. ferraro è evidente una chiara differenziazione tra le due unità che compongono il profilo, con un livello di maggiore alterazione pedogenetica per quanto riguarda gli orizzonti più profondi. 55..44.. llaa ppeerrcceennttuuaallee rreessiidduuaa ddeeggllii eelleemmeennttii oorriiggiinnaarrii partendo dai dati ottenuti attraverso le analisi in fluorescenza ai raggi x e assorbimento atomico è anche possibile determinare le variazioni delle quantità relative dei singoli elementi avvenute durante la pedogenesi, attraverso il calcolo della percentuale residua degli elementi originari 4 (percentage of element remaining busacca, 1982; busacca et al., 1988; busacca e singer, 1989). in questo caso, la percentuale residua degli elementi originari è stata calcolata riferendosi alla composizione chimica del residuo insolubile della dissoluzione del calcare come parent material ed utilizzando lo zirconio come elemento indice. alla luce del fatto che il profilo si è sviluppato a partire da almeno due distinti materiali, come determinato dalla valutazione di uniformità del parent material (§ 5.1.), i risultati che si ottengono per le due porzioni del profilo sono profondamente diversi (tab. 3). ciononostante, è sembrato significativo procedere con la indicizzazione, quanto meno per un confronto quantitativo tra le due unità. in realtà, il problema appare ancora più complesso in quanto, sia per il gruppo di orizzonti bw1 e bw2, sia per l’orizzonte 2bt1 si ricava una generalizzata presenza di arricchimenti (valori residui che superano il 100%). di solito, tali arricchimenti sono legati all’esplicarsi dei fenomeni pedogenetici, che provocano una concentrazione degli elementi più stabili, a causa della perdita per alterazione di quelli meno stabili (e.g. busacca e singer, 1989). nel caso specifico, però, la percentuale residua non sembra seguire solamente questo schema: sono infatti presenti anche arricchimenti di elementi di facile alterazione (e.g. sodio e magnesio) accanto a perdite di elementi più stabili (e.g. titanio). appare chiaro come il residuo insolubile non costituisca, da solo, il materiale originario su cui ha avuto luogo la pedogenesi, ma debba, necessariamen137 fig. 6 l’indice di arrossamento del profilo del monte casto reddening index of mount casto profile. ssiioo22 aall22oo33 ffee22oo22 mmnnoo ttiioo22 pp22oo55 mmggoo nnaa22oo ccaaoo kk22oo bb11 - cc 48.74 85,87 83.96 158.58 67.55 55.12 151.39 370.48 20.60 217.53 bb11 - mm 28.09 60.95 57.89 27.93 43.32 46.61 80.83 180.62 39.66 165.88 bb11 - ff 27.33 129.78 135.95 138.81 57.09 186.81 297.79 80.60 37.36 211.66 bb22 - cc 41.84 101.22 97.04 184.30 64.41 31.38 163.71 538.90 20.70 245.59 bb22 - mm 28.91 80.87 81.23 5.45 48.41 36.84 118.12 163.60 30.84 187.67 bb22 - ff 27.62 121.71 127.49 130.17 53.54 175.19 279.27 75.58 42.78 198.50 22bbtt11 - cc 37.16 152.75 189.58 112.96 72.50 122.55 364.26 215.93 36.10 245.13 22bbtt11 - mm 37.95 131.26 153.55 166.94 69.96 76.69 327.70 201.44 104.46 237.67 22bbtt11 - ff 36.56 172.62 178.67 217.31 78.18 157.20 537.20 427.01 90.58 346.88 rreessiidduuoo 100 100 100 100 100 100 100 100 100 100 tab. 3 la percentuale residua degli elementi originari del profilo del monte casto, riferita alla composizione chimica del residuo insolubile della dissoluzione del calcare del substrato. percentage of element remaining of mount casto profile, using the insoluble residue of limestone dissolution as parent material 4 eh x ipm %er = –––––––– x 100 epm x ih • %er percentuale residua dell'elemento considerato nell'orizzonte (rispetto ad un contenuto originale del parent material pari al 100%); • eh concentrazione dell'elemento considerato nell'orizzonte; • epm concentrazione dell'elemento considerato nel parent material; • ih concentrazione dell'elemento indice (titanio o zirconio) nell'orizzonte; • ipm concentrazione dell'elemento indice (titanio o zirconio) nel parent material. paleosuoli tipo terra rossa ... te, essere stato addizionato da contributi di materiale alloctono. tali contributi risultano massimi, se non esclusivi, per quanto riguarda l’unità superficiale, mentre più limitati, anche se evidenti, per l’orizzonte 2bt1. venendo ad osservazioni più strettamente pedogenetiche, è possibile notare come per l’orizzonte 2bt1 incrementi evidenti siano relativi a ferro, alluminio e manganese, cioè elementi legati ai fenomeni di rubefazione, di formazione di noduli e neoformazione e/o translocazione di argille. viceversa gli incrementi che tale orizzonte manifesta per magnesio, sodio, fosforo e parzialmente per il potassio (elemento stabile), sarebbero da imputarsi, in massima parte, al contributo di materiale di provenienza esterna. anche l’incremento di alluminio nell’unità profonda potrebbe essere imputabile almeno in parte ad una contaminazione eolica a lungo raggio (molinaroli et al., 1993) e non solo al manifestarsi dei fenomeni pedogenetici, precedentemente citati. 66.. ddiissccuussssiioonnee il profilo identificato e descritto sulle pendici del monte casto è costituito da due unità pedologiche distinte che vanno a formare un profilo composito: l’unità profonda è costituita dagli orizzonti 2bt1 e 2bt2, quella superficiale, dagli orizzonti o, bw1 e bw2. le due unità sono distinguibili in base alle loro caratteristiche morfologiche, chimiche e fisiche, ed anche attraverso i parametri utilizzati per evidenziarne il diverso grado di sviluppo morfologico e di espressione della pedogenesi. per quanto riguarda l’unità profonda, essa è costituita da un suolo fersiallitico (duchaufour, 1983), una terra rossa, che mostra le sue tipiche caratteristiche micromorfologiche, chimiche (rubefazione), granulometriche (tenore in argilla). in particolare, per quanto riguarda la micromorfologia, la relativa scarsità di figure pedologiche tessiturali sulla superficie dei vuoti non è in contraddizione con lo sviluppo di suolo fersiallitico, quanto piuttosto con l’incorporazione di tali figure nella massa di fondo a seguito di processi di shrink – swell, che inducono una b-fabric striata, come sintetizzato da fedoroff (1997). inoltre, per quanto riguarda i rapporti tra la sequenza profonda ed il substrato, non vi sono state identificate evidenze di fenomeni di trasporto lungo versante a carico di tali orizzonti: è dunque possibile ipotizzare che il substrato calcareo costituisca (almeno in parte) il parent material di tale porzione di suolo. d’altro canto, occorre anche considerare la terra rossa come un suolo di origine poligenetica, in cui si sommano gli effetti di diversi processi pedogenetici con una intensità relativa che può essere estremamente variabile da caso a caso (cremaschi, 1987; fedoroff, 1997; trombino, 1998): in questo caso risultano evidenti apporti di materiale esterno, probabilmente di natura eolica ad ampio raggio, come confermato dallo squilibrio chimico esistente tra la composizione del residuo insolubile della dissoluzione del calcare, ed il suolo stesso. infine, la sequenza profonda manca degli orizzonti superficiali, ha quindi subito una troncatura, causata da fenomeni di tipo erosionale. un primo elemento di caratterizzazione dell’unità superficiale è dato dal parent material dal quale essa si è formata: le caratteristiche sedimentologiche degli orizzonti bw1 e bw2 sembrano indicare la deposizione di una o più coltri di loess successivamente pedogenizzate. accanto a questa sorgente di tipo eolico occorre considerare la presenza di materiale messo in posto da fenomeni di versante, in particolare per l’orizzonte bw2, nel quale sono stati identificati pedorelitti arrotondati e papulae. tali figure, infatti, sono legate a fenomeni di colluviazione (mücher et al., 1972; bresson, 1974; cremaschi, 1991). dal punto di vista dell’alterazione pedogenetica, essa risulta essere stata sensibile anche per l’unità superficiale, anche se di intensità molto minore rispetto a quella della terra rossa. la superficie che separa le due unità è di facile identificazione, ma gli orizzonti di cui essa costituisce il limite mostrano una zona di transizione, che permette di ipotizzare un certo riarrangiamento. tale riarrangiamento risulta significativo in quanto sembra indicare che la separazione “fisica” delle due unità non vada semplicemente intesa come un evento unico, di breve durata. due sono infatti gli aspetti rilevanti di questa condizione: in primo luogo è possibile invocare un’alternanza di fasi di aggradazione e degradazione del profilo che, in corrispondenza della discontinuità, hanno aumentato il grado di riorganizzazione del materiale. in secondo luogo, la deposizione di una coltre di materiale loessico è un evento che interessa archi di tempo relativamente lunghi, con frequenti apporti di modeste quantità di materiale: un tipo di deposizione che implica un rallentamento piuttosto che una netta interruzione dei fenomeni pedogenetici (cremaschi, 1987; cremaschi e busacca, 1994; busacca e cremaschi, 1998). 77.. ccoonncclluussiioonnii la pedogenesi del profilo descritto sul monte casto presenta caratteristiche polifasiche. partendo dal basso, nel profilo è registrata una prima fase pedogenetica piuttosto spinta, che ha portato alla formazione di un suolo di tipo terra rossa, evidenza di una pedogenesi fersiallitica in clima mediterraneo (duchaufour, 1983). questo primo momento è stato seguito da una interruzione della pedogenesi, connessa ad una fase climatica che ha portato alla troncatura e all’erosione del profilo, quindi alla deposizione di materiale “fresco”. tale materiale risulta di origine prevalentemente eolica (loess), con un moderato apporto dovuto a fenomeni di colluviazione lungo il versante. molto probabilmente le fasi di degradazione del profilo sono state più di una, e l’apporto di materiale ha interessato un intervallo di tempo significativo, coincidente, almeno in parte, con la ripresa della pedogenesi. le fasi pedogenetiche più recenti, che hanno interessato la coltre di sedimenti eolici, sono state sicuramente meno intense della fase antica, ma comunque caratterizzate da processi di decarbonatazione, di scarsa translocazione di argilla e di moderata rubefazione. infine, appare necessario puntualizzare alcune osservazioni paleoclimatiche e cronologiche. la genesi geomorfologica della paleosuperficie su cui si sviluppa la terra rossa al tardo terziario (chardon, 1975), permette di collocare il termine post quem per l’origine e lo sviluppo di questo paleosuolo nel quatenario. d’altra parte, lo sviluppo di suoli con caratteristiche simili a quelle degli orizzonti profondi del profilo descritto necessita di specifiche condizioni climatiche e ambientali che possono essere connesse a periodi caldi come quelli occorsi prima del pleistocene glaciale (dunque pleistocene inferiore cremaschi, 1987; cremaschi e ginesu, 1990) o durante gli interglaciali del pleistocene medio (magaldi et al., 1985; magaldi e bidini, 1991). mancando elementi certi per datare la fase pedogenetica antica e le fasi pedogenetiche successive e, alla luce della natura poligenetica della terra rossa, l’attribuzione cronologica del paleosuolo ad uno dei periodi sopracitati risulta alquanto difficoltosa. il confronto dei livelli di alterazione raggiunti da paleosuoli simili, citati in letteratura, non risulta definitivo a causa della non corrispondenza geografica dei diversi profili: probabilmente solo uno studio pedostratigrafico dell’area potrebbe contribuire alla risoluzione di tale problema cronologico, seppure in modo relativo. ciononostante, il caso di studio del monte casto 138 l. trombino & f. ferraro risulta così un ulteriore esempio di come il suolo resti un imprescindibile strumento nella ricostruzione del nostro passato più recente, proprio in virtù della sua sensibilità alle variazioni che interessano litosfera, biosfera e atmosfera, di cui esso costituisce l’interfaccia. parte integrante di uno studio paleopedologico sono, in questo senso, tutti gli approcci in grado di mettere in luce, con la maggiore sensibilità possibile, le tracce di queste variazioni, registrate sotto varia forma all’interno del profilo del suolo. aappppeennddiiccee ddeessccrriizziioonnee ddeellllee sseezziioonnii ssoottttiillii le descrizioni sono state effettuate secondo i canoni proposti nel handbook for soil thin section description (bullock et al., 1985). talora, nel corso della discussione è stata parzialmente utilizzata la terminologia del sistema descrittivo proposto da brewer (1964). le classi di frequenza nella descrizione sono state attribuite secondo le “general purpose classes” (bullock et al. 1985) come segue: più che dominante > 70 %; dominante 50-70 %; comune 30-50 %; frequente 15-30 %; scarso 5-15 %; raro < 5 %. bbww11 microstruttura e porosità: microstruttura subangular blocky; comuni planes ad andamento ortogonale e lume dalla dimensione massima della sabbia fine media, scarsi canali a lume dalla dimensione massima della sabbia grossolana, scarsi vuoti di costruzione in corrispondenza di un livello organico. massa di fondo: materiale grossolano costituito da comuni grani di quarzo, subarrotondati, lisci, equidimensionali tabulari, di dimensioni fino alla sabbia grossolana, frequenti lamine di mica, subangolari, ondulate, tabulari, di dimensioni fino alla sabbia fine; materiale fine costituito da una massa di argilla, limo e ossidi di ferro, bruno giallastra, nebulosa a mosaico, con b-fabric cristallitica; limite c/f 10 µm, rapporto c/f 45/55, distribuzione relativa c/f porfirica. costituenti organici: resti vegetali parzialmente decomposti, concentrati nella parte superiore della sezione sottile. figure pedologiche: amorfe scarsi noduli di fe-mn, tipici, di dimensioni fino alla sabbia grossolana, scarse impregnazioni di fe-mn. bbww22 microstruttura e porosità: microstruttura subangular blocky; comuni planes a lume dalla dimensione massima della sabbia fine media, rari canali a lume dalla dimensione massima della sabbia media; presenza di aggregati arrotondati a matrice argillosa rossastra. massa di fondo: materiale grossolano costituito da comuni grani di quarzo, subarrotondati, lisci, equidimensionali tabulari, di dimensioni fino alla sabbia grossolana, frequenti lamine di mica, subangolari, ondulate, tabulari, di dimensioni fino alla sabbia fine, rari frammenti di selce subarrotondati, ruvidi, tabulari, con tracce di alterazione superficiale di dimensioni fino alla ghiaia; materiale fine costituito da una massa di argilla, limo e ossidi di ferro, rosso giallastra, opaca nebulosa, con b-fabric cristallitica a mosaico; limite c/f 10 µm, rapporto c/f 45/55, distribuzione relativa c/f porfirica a spazio da singolo a doppio. figure pedologiche: tessiturali, rari frammenti arrotondati di rivestimenti di argilla rosso giallastri; amorfe scarsi noduli di fe-mn, tipici, di dimensioni fino alla sabbia grossolana, scarse impregnazioni di fe-mn. 22bbtt11 microstruttura e porosità: microstruttura subangular blocky, crack all’interno dei poliedri; comuni planes a lume dalla dimensione massima della sabbia fine media, rari canali e camere a lume dalla dimensione massima della sabbia. massa di fondo: materiale grossolano costituito da scarsi grani di quarzo, subarrotondati, lisci, equidimensionali tabulari, di dimensioni fino alla sabbia fine, rare lamine di mica, subangolari, ondulate, tabulari di dimensioni fino alla sabbia fine, rari frammenti di selce di dimensioni fino alla ghiaia; materiale fine costituito da una massa di argilla ossidi di ferro, rossa, opaca a b-fabric maculata reticolare striata; limite c/f 2 µm, rapporto c/f 25/75, distribuzione relativa c/f porfirica a spazio aperto. figure pedologiche: tessiturali, rari rivestimenti di argilla, rosso giallastri, non continui, tipici, sottili, sulla superficie dei vuoti, rari frammenti arrotondati di rivestimenti di argilla rossi; amorfe scarsi noduli di fe-mn, tipici, di dimensioni fino alla sabbia grossolana. 22bbtt22 microstruttura e porosità: microstruttura subangular blocky, crack all’interno dei poliedri; comuni planes a lume dalla dimensione massima della sabbia fine media, rari canali e camere a lume dalla dimensione massima della sabbia grossolana. massa di fondo: materiale grossolano costituito da scarsi grani di quarzo, subarrotondati, lisci, equidimensionali tabulari, di dimensioni fino alla sabbia fine, rare lamine di mica, subangolari, ondulate, tabulari di dimensioni fino alla sabbia fine, rari frammenti di selce di dimensioni fino alla ghiaia; materiale fine costituito da una massa di argilla ossidi di ferro, rossa, opaca a b-fabric maculata reticolare striata; limite c/f 2 µm, rapporto c/f 20/80, distribuzione relativa c/f porfirica a spazio aperto. figure pedologiche: tessiturali, rari rivestimenti di argilla, rosso giallastri, non continui, tipici, sottili, sulla superficie dei vuoti; amorfe scarsi noduli di fe-mn, tipici, di dimensioni fino alla sabbia grossolana. rriinnggrraazziiaammeennttii il nostro primo ringraziamento va a mauro cremaschi: senza il suo aiuto, il suo incitamento e soprattutto senza il suo insegnamento questo lavoro non sarebbe esistito. quindi vorremmo esprimere la nostra gratitudine a lucas vanmechelen che ha stimolato il nostro interesse verso i problemi di contaminazione eolica delle terre rosse italiane. un sentito ringraziamento va ai referees stefano carnicelli e pierluigi pieruccini, che, con le loro osservazioni, ci hanno invitato ad ampliare le nostre vedute sul problema in esame, permettendoci di migliorare la qualità dell’articolo. infine un ringraziamento speciale va a pietro mario rossi, direttore del centro di studio per la geodinamica alpina e quaternaria di milano, per l’incoraggiamento ed il supporto fornitici. bbiibblliiooggrraaffiiaa arduino e., barberis e., carraro f. e forno m.g. (1984). estimating relative ages from iron-oxide / totaliron ratios of soils in the western po valley, italy. geoderma, 3333:: 39-52. 139paleosuoli tipo terra rossa ... avery b.w. e bascomb c. l. [ed.] (1974). soil survey laboratory methods. soil survey technical monograph, 66, harpenden. bresson l.m. (1974). a study of integrated microscopy: rubefaction under wet temperate climate in comparison with mediterranean rubefaction. in: rutherford g.k. [ed.], soil microscopy, pp. 526541. the limestone press, kingston. brewer r. (1964). fabric and mineral analysis of soils. john wiley and sons, new york. bullock p., fedoroff n., jongerius a., stoops g., tursina t. e babel c. (1985). handbook for soil thin section description. waine research publication, albrighton. busacca a.j. (1982). geologic history and soil development, northeastern sacramento valley, california. ph.d. dissertation, university of california, davis. busacca a. e cremaschi m. (1998). the role of time versus climate in the formation of deep soils of the appennine fringe of the po valley, italy. quaternary international, 5511//5522: 95-107. busacca a.j. e singer m.j. [eds.] (1989). pedogenesis of a chronosequence in the sacramento valley, california, usa, ii. elemental chemistry of silt fractions. geoderma, 4444: 43-75. busacca a.j., singer m.j. e verosub k.l. (1988). late cenozoic stratigraphy of the feather and yuba rivers area, california, with a section on soil development in mixed alluvium at honcut creek. u.s. geological survey bulletin, 1590-g. chardon m. (1975). les préalpes lombardes et leurs bordures. librairie champion, paris. cremaschi m. (1978). unità litostratigrafiche e pedostratigrafiche nei terreni quaternari pedeappenninici; loess e paleosuoli tra il fiume taro e il torrente sillaro. geografia fisica e dinamica del quaternario, 1: 4-22. cremaschi m. (1987). paleosols and vetusols in the central po plain (northern italy): a study in quaternary geology and soil development. unicoply, milano. cremaschi m. (1991). paleosuoli. in: cremaschi m. e rodolfi g. [ed.], il suolo, pp. 283-317. nuova italia scientifica, roma. cremaschi m. (1992). la penisola italiana nel quaternario: aspetti geologici e geoarcheologici. in: guidi a. e piperno m [ed.], preistoria d’italia, pp. 15-39. laterza, bari. cremaschi m. e busacca a. (1994). deep soils on stable or slowly aggrading surfaces: time versus climate as soil-forming factors. geografia fisica e dinamica quaternaria, 1177: 19-28. cremaschi m. e ginesu s. (1990). morfogenesi e pedogenesi tardo terziaria e pleistocenica antica nella nurra occidentale (sardegna). nota preliminare. geografia fisica e dinamica quaternaria, 1133: 81-82. curioni g. (1877). geologia applicata delle province lombarde. milano. duchaufour ph. (1983). pédologie 1: pédogenèse et classification. masson, paris. fedoroff n. 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(1991). microscopic and submicroscopic characterization of a well developed plinthite in a buried middle pleistocene soil in northern tuscany (italy). quaderni di scienza del suolo, iiiiii: 31-44. molinaroli e., guerzoni s. e rampazzo g. (1993). contribution of saharan dust to the central mediterranean basin. in: johnsson m.j. e basu a. [ed.], processes controlling the composition of clastic sediments, geological society of america, special paper 228844: 303-312. mücher h.j., carballas j., guitian ojea f., jomgerius p.d., kroonenberg s.b. e villar m.c. (1972). micromorphological analysis of effects of alternating phases landscape stability on two profiles in galicia, north west spain. geoderma, 88: 241-266. munsell ® (1994). soil color charts. 1994 revised edition. munsell ® color, new windsor. olson c.g., ruhe r.v. e mausbach m.j. 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(1965). rilevamento geologico dell’anfiteatro morenico frontale del garda, dal chiese all’adige. memorie della società italiana di scienze naturali e del museo civico di storia naturale di milano, xiv, i. vidic n. (1994). pedogenesis and soil age relationships of soils on glacial outwash terraces in the ljubljana basin. ph.d. thesis. university of colorado. yaalon d.h. (1997). soils in the mediterranean region: what makes them different. catena, 2288: 157-169. zippe f.x.m. (1853). über die grotten und höhlen von adelsberg, lueg, planina und laas. wien. 140 ms. ricevuto marzo 2002 ms. received: march 2002 l. trombino & f. ferraro ojs 733 peresani 185-204.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 36 (2), 2023, 185-204 1. introduction because of its strategic position between africa and continental europe, italy with its variegated landscape is particularly suitable for palaeoecological, archaeological and palaeoanthropological studies. during the pleistocene, distinct human migration waves occurred in western eurasia, particularly in its southern area, leaving ephemeral and progressively more and more consistent traces framed in their ecological context. continental italy and, above all, peninsular italy preserve abundant biological and cultural fossil record, placed in peculiar geographical and ecological contexts that stimulate the investigation of population dynamics, adaptations, and cultural transition across the whole pleistocene. in the last two decades there have been a number of new discoveries of sites, cultural items and human remains from across the country spanning from the lower to the upper palaeolithic. in the meantime, many materials, specimens, chronologies have been reconsidered and re-evaluated to increase our knowledge of crucial findings attributed to homo heidelbergensis, homo neanderthalensis and homo sapiens populations in the widest western eurasian scenario. italy is mostly a mountainous and coastal country. the alpine chain, mainly e-w oriented, reaching elevations >4500 m in its western range, alongside with the apennines, nw-se oriented, with elevations >2500 m, acted as important ecological barriers, respectively towards continental europe and splitting the peninsula in two sides. the western one is influenced by the mediterranean climate, while the eastern side is more subjected adaptations and cultures of pleistocene humans in italy marco peresani dipartimento di studi umanistici, sezione di scienze preistoriche e antropologiche, univ. degli studi di ferrara, ferrara, italy. istituto di geologia ambientale e geoingegneria, consiglio nazionale delle ricerche, milano, italy. corresponding author: marco peresani <psm@unife.it> abstract: italy preserves abundant biological and cultural fossil record, placed in peculiar geographical and ecological contexts that stimulate the study of population dynamics, adaptations, and cultural transitions during the whole pleistocene. such a variegated territory, bounded by the alpine chain and longitudinally split by the apennines, hosted distinct migration waves attributed to unidentified hominins, and to homo heidelbergensis, homo neanderthalensis, homo sapiens in a heterogeneous scenario subjected to profound changes during extreme sea-level lowering. the first human colonization occurred around the early to middle pleistocene transition, presumably driven by major faunal renewals which invested southern europe. these first proofs are documented in the oldest sites, pirro nord and monte poggiolo, with lithic industries based on core-and-flake technology. after a gap in the evidence of human settlements between mis19 and mis17, the earliest acheulean makes its appearance in southern italy starting from 661-614 ka. large cutting tools typical of this complex remain however poorly represented throughout the early middle pleistocene, in favour of the tiny and medium-sized flakes which feature the lithic industries until the conventional end of the lower palaeolithic. specifically, these small tools mark the middle pleistocene interaction between hominins and elephants, as documented in many sites in central italy. as regards the middle palaeolithic, its archaeological and anthropological record looks more consistent and proves that neanderthals inhabited southern europe and continental italy. the neanderthal record refers to settlement patterns and mobility strategies in the geographic and environmental districts that feature most of the regions at the alpine fringe, along the apennine chain and the rocky coasts. settlements have complementarity character, with long-term occupations and other locations used for short time, particularly caves and sheltered sites, where the stratigraphic sequences record multioccupations covering large time intervals and repeated environmental changes. as a matter of fact, some environmental changes are related to cultural turnovers like the appearance of the mousterian quina during mis4 in the north of italy. hunting and dietary behaviour reconstructed from a number of sites stimulates debate around possible convergencies or divergencies between neanderthals and the first homo sapiens communities who started settling italy since about 44-43 cal ka bp. pieces of the neanderthal -sapiens biocultural transition with contested attributions have been unveiled in recent years at key archaeological sites, either in the north and in the south of italy, producing an incontestable contribution for reconstructing these dynamics in europe. this is specifically the case of the uluzzian with its cultural package of lithic and bone technologies and ornamental beads, that follows in time the oldest known cultural expressions of homo sapiens in other regions of western eurasia. the spread of early sapiens is also related to the aurignacian and marks another intriguing cultural dynamic of the upper palaeolithic, prolongating across the last glacial maximum and the late glacial, two turning points for the bio-geographical, anthropological and cultural evolution marked by the loss of large continental plains and the rearrangement of all ecozones of human populations. as consequence of the late glacial interstadial warming, a large-scale epigravettian colonization of the mountain ranges started and continued in the mesolithic until the disappearance of those hunter-gatherer populations. keywords: settlement, human adaptation, migration, culture, palaeolithic. https://doi.org/10.26382/amq.2023.08 to continental conditions. extensive and long-lasting tectonic activity, together with the major geomorphic processes attributable to glacial, fluvial and marine erosion, fluvial sedimentary aggradation, and volcanic activity contributed to produce a heterogeneous physiography, with considerable extension of the coasts during the extreme sea-level lowering. furthermore, given its latitudinal extension from 38° to 47° n, italy is featured by a strong climatic gradient, in turn favouring a marked biodiversity also enhanced by the extensive variety of bedrocks. the pattern of modern precipitation values ranges from >2000 mm/year in the prealpine belt of northern italy to <500 mm/year in some areas especially of southern italy and sicily. during the pleistocene global climatic turnovers, these values, alongside the average t° dramatically varied and impacted on the extention of the icesheets, landmass, biomass and ecological variability with maintenance of remarkable differences across the peninsula and especially between the western and eastern sides. 2. the oldest lower palaeolithic settlements and the transition from the early to middle pleistocene when, where and in which conditions the first colonization of western mediterranean europe by hominins occurred is one of the most debated topics in palaeoanthropology and prehistoric archaeology. researchers agree on human’s dispersal events towards w europe during the late early pleistocene, probably occurred earlier than 1.2 ma, as demonstrated by chronometrically dated finds in spain (huguet et al., 2017). furthermore, models elucidate that this dispersal was likely part of the progressive faunal renewal, which also involved some large mammals of african origin during the early pleistocene (manzi et al., 2011). such a first distinct wave of humans is documented at orce and atapuerca sima del elefante and has been referred to homo antecessor, which remains were found associated with stone artefacts attributed to the so-called mode 1. these industries are largely known in many sites of the mediterranean and continental regions. large discontinuities affect the archaeological record up to the early middle pleistocene for a range of taphonomic, visibility and research reasons, with no exclusion of ecological conditions. human dispersal into europe is thus attributable to morphologically derived hominins, well known from atapuerca (bermúdez de castro et al., 2011) and to several sites where bone remains broadly included within the homo sp. were found. this significant human presence has been related to the major faunal renewal that characterised the early to middle pleistocene transition. this hypothesis is supported by evidence of a major episode in the reorganization of mammalian fauna since at least 1.3 ma, with dispersals of taxa most of which persisted throughout the middle pleistocene and respective reconstruction of mammalian faunal complexes (palombo, 2010). as expressed above, the italian peninsula is an important benchmark for reconstructing the chronological and cultural data about the diffusion of genus homo outside africa. archaeological sites (fig. 1) testify to an early occupation of italy and corroborate models about the exit from africa that could have spread from the middle east. the oldest archaeological evidence comes from pirro nord in apulia, s italy, dated on biochronological base to 1.6-1.3 ma. the site counts a large assemblage of fossil vertebrates (pirro nord faunal unit) and short reduction sequences deeply adapted to obtain flakes (arzarello et al., 2012). however, this chronological interval has been criticized by muttoni et al. (2018) because of the lack of magneto-stratigraphical and numerical dates. thus, an age of >0.78 ma has been proposed for pirro nord, instead, according to the biochronology of the mammal association, the correlation between bones and cut-marked bones, stone tools and the sedimentary infill of the karts structure. if the old chronology is confirmed, a long gap separates pirro nord from the open-air site of cà belvedere di monte poggiolo in the n apennine, dated to about 0.9 ma by esr and palaeomagnetism (muttoni et al., 2011). the site is characterized by core-on-flake technology and abundant refitting which allowed the reconstruction of complete reduction sequences (peretto et al., 1998). thanks to refits, is has been possible to understand than local raw materials only allowed the production of short reduction sequences (ssda or centripetal) to obtain flakes which were rarely shaped through retouched edges. this first phase of occupation fits perfectly with the other european sites dated between 1.3 and 0.9 ma. however, the oldest italian sites do not present retouched lithic elements in their assemblages, although at pirro nord it might be observed a strong predetermination (chelli cheheb et al., 2019). 3. the middle pleistocene, the acheulean and other complexes ultimately, there are no archaeological sites between marine isotope stage (mis) 19 and mis 17 and the sites recorded in an indisputable stratigraphic context between mis 17 and mis 12 are few and fragmented both temporally and spatially (fig. 1). however, the timing and occurrence of the settlement in this timespan and the related technical behaviours are subjected to different interpretations (muttillo et al., 2021). the middle pleistocene human fossil record is represented by the partial femur shaft from venosa notarchirico (moncel et al., 2020), and the human deciduous incisor from isernia la pineta (peretto et al., 2015). it is worth to mention ceprano in southern latium for human remains, as a calvarium in primary deposits was recovered and dated to 400 ka. it has no apomorphic neanderthal trait, while shows similarities with specimens attributed to homo heidelbergensis in e africa (manzi et al., 2001). it supports the phylogenetic significance of ceprano as the best candidate to represent the ancestral morphology of this putative polymorphic species (manzi, 2016). nearby this site, the human teeth rcovred at fontana ranuccio (k/ar dated to 0.46, muttoni et al., 2009) shows morphological traits supporting an evolutionary continuity between the mid pleistocene humanity and neanderthals (rubini et al., 2014; zanolli et al., 2018). this affinity, alongside with the apparent contrast with ceprano, hints at more archaic morpholo 186 peresani m. (moncel et al., 2020). during this phase, large cutting tools are poorly or not represented in the italian peninsula. the lithic assemblage of isernia la pineta (583561 ka) reflects this situation. it is mainly composed of small and medium-sized flakes of local flint and limestone but no bifaces (peretto et al., 2015). these sites share similar riverine contexts despite the differences observed in the archaeological assemblages (muttillo et al., 2021). one of the most intriguing pieces of evidence of middle pleistocene hominin behaviour in italy is related to the interaction between hominins and elephants, as gies retained by 400 ka populations in italy, contrary to other populations in southern and central europe (manzi, 2016). these, instead, already showed varying grades of morphological progression towards the typical neanderthal assemblage of traits, thus suggesting the occurrence of different sub-species of homo heidelbergensis in the same timeframe. profound changes between the first appearance of human groups in southern europe and the early use of hand axes occurred at the end of the middle pleistocene climatic revolution. notarchirico is the earliest acheulean assemblages in italy, and it is dated to 661-614 ka 187 adaptations and cultures of pleistocene humans in italy fig. 1 most relevant lower palaeolithic sites in italy: 1) visogliano; 2) quinzano; 3) monte poggiolo; 4) ficoncella; 5) castel di guido; 6) torre in pietra; 7) polledrara di ceccanibbio; 8) fontana ranuccio; 9) valle giumentina; 10) pirro nord; 11) isernia la pineta; 12) guado san nicola; 13) roccamonfina; 14) notarchirico; 15) atella (source http://tinitaly.pi.ingv.it; elab. by d.delpiano). testified from elephant bones with presence of anthropogenic surface modifications. such evidence can be found to archaeological and taphonomic records in africa, europe, and asia where remains of palaeoloxodon antiquus and lithic tools coexist (agam & barkai, 2018; panagopoulou et al., 2018 and references therein). medium sized lithic tools with residues and use-wear related to animal tissues processing, found in association with carcasses and articulated bones, corroborate the involvement of these animals in the diet of lower palaeolithic hominins (aranguren et al., 2019). elephants were not exclusively exploited for meat, fat, and marrow: their bones were also used as raw material to produce flakes and various types of large bone tools among such as handaxes (barkai, 2021; villa et al., 2021). given the paramount importance of these animals as sources of food and raw material it might be assumed that also affected hominins’ behaviour and their landscape exploitation strategies (lemorini et al., 2022). under this light, a remarkable site of reference is la polledrara di cecanibbio where elephant carcass and lithic implements were found in fluvial and fluvio-palustrine fossiliferous deposits included in the ponte galeria sequence 6 of the aurelia formation (mis10 and mis9; santucci et al., 2016). the optimal quantity and degree of preservation of the faunal remains thanks to the contemporaneous re -sedimentation of a volcanic unit dated 325–310 ka (pereira et al., 2017), allowed to unearth large mammals like palaeoloxodon antiquus and bos primigenius, together with lithic and bone artifacts but no bifaces. the interpretation of butchering activities going on the site is consequence of the over 500 stone flakes recovered around the carcass of a single elephant in anatomical connection. data obtained from a recent study and compared to previous published papers (cerilli & fiore, 2018) shed light on a sequence of events occurring over a long-time span from a fresh carcass to a completely bare skeleton. the human interaction with the body of the elephant, entrapped in the mud, consisted in a series of butchering sessions occurring in a few days (lemorini et al., 2022). these interactions probably followed of the organization of a hunting session. another hypothesis is that the elephant carcass, probably partly scavenged by other predators, was found during routine exploration and exploitation of the landscape and totally scavenged by hominins adapted with flexible dietary behavior and equipped with a toolkit suitable to these situations. 4. neanderthals and the middle palaeolithic due to the blurred chronology of the middle palaeolithic, especially of its earliest phase, the understanding of the variability and evolutionary patterns of the late acheulean and first mousterian techno-complexes is quite limited. nonetheless, a consistent archaeological record attests that neanderthals inhabited s europe and italy throughout the entire middle palaeolithic (fig. 2). starting from the earliest attestations, one of the most spectacular pieces of evidence is reported at foresta ichnosite in sw italy, also known as ‘devil’s trails’, impressed on top of the ls7 pyroclastic unit dated 345350 ka (mis 10). at this site, a minimum number of three individuals left isolated footprints and trackways moving downslope but also in the opposite direction with respect to the others (panarello et al., 2020; mietto et al., 2022). human fossil specimens have been found all over italy and bear a mixture of archaic features and more progressive (neanderthal) traits, as attested by the skeleton from altamura (s italy) and skulls found at saccopastore. skulls, teeth and appendicular skeleton remains were found at grotta guattari also during recent excavations (rolfo et al., in press). isolated teeth come from several sites from northern to sougìthern italy, like ciota ciara, riparo broion, riparo tagliente, grotta fumane, grotta de nadale and grotta taddeo, grotta cavallo, spinadesco, and campoverde (buzi et al., 2021). the altamura skeleton is one of the most complete human specimens of late middle pleistocene in europe. it was found in the karstic cave of lamalunga in puglia and apparently was not associated to any lithic artifact. it is covered of large calcite concretions, u/th dated between 172±15 and 130.1±1.9 ka (lari et al., 2015). bones support the idea that the individual remained trapped in the karstic system and died right in the place of deposition, as any sign of transportation, modification or deformation was observed. neanderthals’ settlement patterns and mobility strategies varied in the different italian geographic and environmental areas, although adaptations to ecological contexts are still poorly known all across many districts. the settlements are characterised by a complementarity between long-term occupations and locations showing short-time, repeated occupations, particularly in caves and sheltered sites where stratigraphic sequences span wide time intervals and cover an ensemble of environmental changes (romagnoli et al., 2022). the technoeconomic variability might be explained by different mobility strategies, technological traditions and neanderthal behaviour. the result is a complex mosaic between expediency and curation in the organization of production and maintenance of stone tools, with continuities and ruptures across time. currently, this dynamic and kaleidoscopic scenario cannot be interpreted according to a universal model either of time or space (romagnoli et al., 2018; delpiano et al., 2019). italy was well-populated by neanderthals all across the mp and especially at its end, as demonstrated by the density of sites. human presence was recorded in caves and shelters, in the open-air on fluvial terraces, hill tops, karst surfaces, mountain ridges. although neanderthal population density cannot be estimated yet, studies on land-use patterns and mobility reveal that their settlements covered a wide biogeographic range, bounded from the north by the pre-alpine fringe and to the south by the marine coasts. unfortunately, due to alpine glaciers and periglacial processes, the archaeological record preserved only on mountain and hilly sectors on the southern alpine slope spared by these processes. the reconstruction of the settlement system can be inferred by sites located on those fluvial terraces situated at the edge of the mountain range, spared by destructive post-depositional processes. the same holds for the apennine range, which hosts several sites also up to its inner ridge. in the ital 188 peresani m. humans all along the pre-alpine area (margaritora et al., 2020). settling this region was favoured by the geographical variability and dense spacing of biotopes which characterize the belt between the upper alluvial plain and the pre-alpine range. presumably, neanderthal groups developed different models of mobility and exploitation of resources across this territory and used the main caves for complex and intense human occupaian alps, mid-altitude caves like for instance the caverna generosa at 1,450 m of altitude in the lombard pre-alps can be viewed as refugia-locations used in function of constrained factors influenced by altitude and ecoclimatic situations (bona et al., 2007). these mountain sites scattered at 1300-1400 m a.s.l., peaking at 1600 m and bearing traces from ephemeral to consistent, might well be integrated within the seasonal movements of 189 fig. 2 selection of middle palaeolithic sites in italy: 1) grotta del rio secco; 2) grotta maggiore di san bernardino; 3) grotta e riparo del broion; 4) covolo de nadale; 5) grotta di fumane; 6) rìparo tagliente; 7) vajo salsone; 8) monte netto; 9) ciota ciara; 10) balzi rossi; 11) san francesco; 12) arma delle manie; 13) ghiardo; 14) podere due pozzi 15) grotta del capriolo; 16) grotta all'onda; 17) campitello; 18) poggetti vecchi; 19) grotta la fabbrica; 20) grotta di cala dei santi; 21) saccopastore; 22) casal de pazzi; 23) grotta guattari; 24) grotta breuil; 25) grotta del fossellone; 26) grotta dei moscerini; 27) grotta reali; 28) monte conero; 29) grotta paglicci e riparo esterno; 30) grotta delle mura; 31) lamalunga; 32) riparo dell'oscurusciuto; 33) grotta del cavallo; 34) grotta romanelli; 35) grotta di castelcivita; 36) grotta della cala; 37) grotta e riparo del poggio; 38) riparo del molare; 39) archi (source http://tinitaly.pi.ingv.it; elab. by d.delpiano). adaptations and cultures of pleistocene humans in italy tions. this was particularly the case of the venetian and carnic pre-alps, where differences in anthropogenic features, spatial patterning, stone knapping methods and bone industries likely reflect different adaptive responses at ecological factors. however, due to the bias in the preservation of the archaeological record, not all the finds share the same informative potentiality. for instance, open-air sites, strongly affected by post-depositional disturbance which caused the impoverishment of past human activity traces with substantial loss of information. at any rate, some information can be acquired also by their location features furnishing details about territoriality and site catchment. as a consequence, aspects of the settlement system inferred from site exploitation territory, site function and raw material circulation are accessible only in a limited range of evidence, the more detailed of which are often provided by the stratified archives (i.e., delpiano et al., 2019). thanks to the layout of these contexts human behavior can be explored in relation to the environmental context: current data on systems in coastal, hill and mountain landscapes can enrich our knowledge on the seasonal nomadism practiced by neanderthals. caves presumably had a main role thanks to their strategic position, being favourable for catchment in different environments through short-range movements. the variety of hunted animal species confirms opportunities to diversify the exploitation of animal resources. if we add the possibility for the human groups to easily access the primary exposures and secondary deposits of chert, we can argue that neanderthal huntergatherers’ ecological adaptations were deeply influenced from the not homogenous distribution of resources, so typical of the italian landscape. this plethora of evidence allowed the reconstruction of neanderthal hunting behaviour. hunting was shaped by game availability in the surroundings, particularly at hilly and mountain landscape lowlands junction rather than specialization or selection of selected taxa, as confirmed by zooarchaeological data. not surprisingly, caves in the pre-alpine and sub-alpine area, located in proximity of a range of ecological contexts, reveal that ungulates were hunted conformably to the respective specific ecological conditions at each site (romandini et al., 2020; terlato et al. 2021). the location and the ecological context of caves placed at low-mid altitude in landscapes dissected by deep valleys with cliffs and steep slopes in proximity to the alluvial plain and the mountain grassland belt, favoured the exploitation of different prey, despite the efforts required to cover the distance from and to the site. although for some context we only have preliminary data, it seems that these sites were used as place where to finalize the processing of carcasses after having begun at the kill site and especially for red-deer and roe-deer. as a matter of fact, as indicated by the pattern of preservation of skeletal elements, selected anatomical parts with high nutritional value, such as limbs, especially hind, and to a lesser extent the cranium, were brought to the site. thus, it can be envisaged well-established and cost-effectiveness patterns in the selection of specific skeletal portions, as a function of factors like the weight of the red-deer and roe-deer carcass portions and the distance between the kill site and the home base (romandini et al., 2014a; terlato et al., 2021). on the other hand, some sites at the edge of the murge karst plateau in southern italy showed hunting adaptation behaviours, where skeletal parts from bos and other ungulates were selected in relation to the exploitation of long bones for the extraction of marrow and the probable use of epiphysis and articular bones as fuel (boscato et al., 2011). further signatures of uncommon hunting and dietary behaviour produced at fumane stimulate debate around possible convergencies or divergencies between neanderthal groups and also with modern human communities. as a matter of fact, the hunting of bears and cave bears by neanderthals marks a particular signature, together with the ones of carnivores and rodents exploited for fur, like fox, which are animals commonly targeted during the upper palaeolithic (romandini et al., 2018a; 2018b). during different periods and mousterian cultures, it can be inferred also the role that birds played in the complexity of neanderthal subsistence, especially when evidence of avifaunal resource exploitation was found at different sites, as shown at fumane (peresani et al., 2011; fiore et al., 2016). birds were likely not an elusive resource, possibly favoured by the ecological conditions and the presence of cliffs in proximity of the sites and their contribution in the dietary balance is far from the amount of protein provided by herbivore prey. these conditions stimulate future investigations to deep our knowledge about the acquisition of birds, the butchering process and the successive consumption. one further point of interest is marked by the variability of technocomplexes all across the late middle palaeolithic, as shown by certain key sites like grotta de nadale, fumane, riparo tagliente, grotta rio secco, grotta madonna dell’arma, grotta guattari, grotta castelcivita, riparo paglicci, riparo oscurusciuto and others. it stimulates debating about neanderthals’ cultural variability, ecology and economy of subsistence related to different methods of chert knapping and the design of a range of lithic tool types. these variables are under the focus of ongoing research when advanced evidence might be achieved following the same approach and protocol of investigation for identifying similarities or divergencies in the exploitation patterns of specific prey. particularly in cases where the zooarchaeological record produces signatures of standardized actions on both soft and hard tissues, systematic practices in the sequence of faunal processing have been assessed. further evaluation whether each range of game available at the site surroundings was exploited following standardized processes but by different cultural groups using distinct lithic technologies and related stone tools, is an intriguing issue (romandini et al., 2020). it is undeniable that this requires in-depth inspections across mousterian sequences, where levallois alternates with discoid, which were the most common technologies used by neanderthals in italy. levallois was the dominant knapping method at most of mp sites, despite of their function, geomorphological and ecological context, raw materials and hunting behaviours of their inhabitants (palma di cesnola, 1996; marciani et al., 2020). currently, early mp technology including levallois and prepared-core technolo 190 peresani m. blanks (peresani et al., 2015) but it was related to both expedient and curated behaviours in different moments across the stratigraphic sequences, probably due to changes in mobility strategies and toolkit provisioning in accordance with site function and the duration of occupation. although its documentation in the archaeological record is still partial, this behaviour might also be correlated to the use of a site as a storage location over time (peresani et al., 2015). amongst the sites showing adaptation to the distribution of resources, it is worth mentioning the pontinian mousterian in coastal latium. this ensemble of industries was based on the exploitation of small pebbles chipped also by bipolar percussion on anvil and further reduced by free-hand percussion or retouched to obtain cortical tools (kuhn, 1990). although dates are uncertain, the pontinian should have been a local technological tradition from mis 5-3. a further example of specific neanderthal adaptation to local resources is attested by the exploitation of callista chione’s marine shells to shape retouched tools (douka & spinapolice, 2012). this behaviour is recognized in several sites along the tyrrhenian and ionian coasts, although their chronological framework is still uncertain (romagnoli et al., 2016). in continuity with the abovementioned dynamic material culture of neanderthals, fumane cave has provided clues on the evolution of human behaviour refusing the view that neanderthals did not make use of symbolic items. rather, they gave attention to the aesthetic or uniqueness of certain materials of biological nature. although direct and indirect evidence are still scanty if compared to the upper palaeolithic, the middle palaeolithic groups a varied ensemble of materials also of inorganic nature like raptor claws, remix feathers, ochre, marine shells, green colour pebbles (peresani et al., 2011; 2021, romandini et al., 2014b). 5. transition from the middle to the upper palaeolithic the pivotal phase of human evolution represented by the middle to upper palaeolithic transition in western eurasia had a definitive impact on humankind. when and how the native population of homo neanderthalensis lived and was definitely replaced by homo sapiens is a subject of heat debate and it is far from being clarified yet. studies focused on the relations between them and their respective ecological conditions and material cultures were carried on based on ecological, behavioural and cognitive spheres of these humans. recently, a multidisciplinary research conducted at key archaeological sites in italy produced an incontestable contribution for reconstructing the bio-cultural dynamics southern europe jigsaws of such an intriguing puzzle with contested attributions of some specific expressions of past human diversity. amongst many archaeological and anthropological records, grotta fumane, riparo broion, riparo bombrini, grotta cavallo, grotta castelcivita, grotta roccia san sebastiano and others contain the most important record and are successfully producing evidence of direct implication for the history of humankind in this strategic area of the mediterranean rim (fig. 3). the last achievements in the reconstruction gy, branching and a large variety of retouched items, is attested since mis 9-8 at cave dall’olio in emiliaromagna (fontana et al., 2013), and in latium (villa et al., 2016). however, in multi-layered sites is attested the alternation or co-presence with other lithic exploitation strategies following the discoid method (e.g., fumane and rio secco, bombrini and riparo mochi and grotta principe, grotta cavallo and riparo bernardini). laminar production is also known in the italian mp. blades were produced both within levallois modalities and as unipolar volumetric debitage (marciani et al., 2020). bladelets are sporadically attested, and the assemblages are never characterised by a sole production method. furthermore, in the assemblages, expeditive productions are usually associated with more formal technologies. as a matter of fact, it seems plausible that the production with discoid knapping methods by certain groups of neanderthals supported them to adopt an opportunistic exploitation of cherts (delpiano et al., 2018). neanderthal behavioural variability is also expressed by the mousterian quina techno-complex, as attested by lithic assemblages found at fumane and de nadale, both chronologically framed in a cold phase of the upper pleistocene between 70 and 60 ka, coincident with mis4. the assemblages consist of cores, large flakes with thin transverse edge or short and thick flakes, and scrapers shaped by three or more orders of stepped -scaled (quina-type) retouch. overall, they share similarities with the quina reduction methods and technofunctional lay-outs identified in w europe, providing opportunities to compare evidence at the large scale in the same chronological interval (delpiano et al., 2022). aside the quina tools, sidescrapers in the italian mousterian industries are the most frequent retouched tools, followed by denticulates, notched tools and rare points. the intensity of retouch and resharpening varies from site to site, as the ratio between retouched and unretouched items. the fact that knappable stones and finished tools were introduced to a given site have been related to multiple factors like the duration of human occupation, site function and cultural patterns, including recycling. chert is the mainly exploited material in the middle palaeolithic sites, and it was generally collected locally and regionally (within 30 km of the site). nevertheless, the presence of very homogeneous resources related to supply areas located more than 100 km away has occasionally been identified and is always present in low percentages in most of the assemblages (negrino & starnini, 2003; porraz & peresani, 2006; spinapolice, 2012). raw material collected from far away sites usually arrived at the site as finished tools as part of a personal toolkit. resources other than chert, like quartzite, jasper, silcrete, limestone, are also attested, although their frequency varies from layer to layer and from site to site, suggesting adaptation of these communities to the local landscape. furthermore, several examples demonstrate that a variable part of the tool-kit was made and maintained not only on exogenous materials, but also on old patinated artefacts, collected, exploited or resharpened and used after their first phase of life and the new functional cycle. at fumane, san bernardino and broion caves it seems that the recycling of previously abandoned and patinated flakes was not focused on specific 191 adaptations and cultures of pleistocene humans in italy of life, subsistence, and cultures of these hominins are resumed in the following sections. 6. homo sapiens and the upper palaeolithic 6.1. uluzzian an important role to unveil these dovels of the mpup transition puzzle is played by the uluzzian cultural complex, which spread across the central mediterranean rim in italy and the south of the balkans (moroni et al., 2018; peresani, 2014). traditionally, it is characterized as a lithic and bone technocomplex that produces flakes and blades with pieces that are splintered or backed, crescent-shaped microliths, as well as endscrapers, bone tools and ornamental beads. at the present state of research, the uluzzian follows in time the presumably oldest known cultural expressions associated to homo sapiens in western eurasia, namely the neronian (slimak et al., 2022) and the initial upper palaeolithic (hublin et al., 2020). the uluzzian, in fact, is attributed to modern humans on an anatomical base of two deciduous teeth discovered in the 60ies in cavallo cave (benazzi et al., 2011). along the italian peninsula, the uluzzian is currently best known by its stratigraphic position placed above the mousterian in cave sedimentary sequences, as in northern italian sites. as a matter of fact, the discovery of assemblages at grotta fumane (peresani et al., 2016) and riparo broion (peresani et al., 2019) proved an expansion of its cultural borders further north from what was thought to be exclusively a southern extension. unfortunately, the stratified sites along the ligurian arch (riel-salvatore & negrino, 2018) and along the southern and eastern margins of the po plain (peresani, 2011; karavanić et al., 2018) are lacking of comparable diagnostic evidence. this geographical space constrained from the apennine, the southern alps, the dinarids and the shallow adriatic reach of mis3, features high ecological diversity, and raises its pivotal importance in influencing human migratory routes. furthermore, interactions between different biocultural worlds are relevant evidence for further increasing the frame of the on-going debate regarding the makers of the uluzzian (zilhão et al., 2015; moroni et al., 2018; peresani et al., 2019), and the biological taxonomy of the settlers recognized at fumane (peresani et al., 2022). additional cultural and taphonomic data from the transitional sequence in question are needed. indeed, serious doubts have been cast on the reliability of the stratigraphic position of the teeth found at grotta cavallo (zilhão et al., 2015), based on the lack of data available to ascertain the consistency of the uluzzian sequence from layers eiii to di. cavallo b and cavallo c teeth were discovered in association with anthropically modified faunal remains, knapped stones, bone tools and marine shells which form the foundation for this technocomplex. due to their state of preservation, uniqueness, tiny size and lack of dentine, the teeth cannot be directly radiocarbon dated. however, moroni and colleagues (2018), based on a recent detailed reexamination from the field notes of arturo palma di cesnola, confirmed that they were recovered from undisturbed deposits. to reinforce their finding context, the analysis of two tephra layers, the y6 and campanian ignimbrite, sandwiching the uluzzian at the base (layer fa) and at the top (layer cii) respectively, dispels doubts on the solidity of the uluzzian at grotta cavallo, and sets its duration not earlier than 45.5±1.0 ka bp and not later than 39.85±0.14 ka bp (zanchetta et al., 2018). this date range does not contradict the previous chronometry based on marine shells, charcoal and a probability distribution function for layer eiii (douka et al., 2014) which has now been directly dated to between 44 and 43 cal ka bp (higham et al., 2022), close to the age ranges at broion and fumane. current research focuses on improvements for this resolution to confirm results with greater certainty. however, in accordance with the cultural marked affinities between the southern site and broion mentioned above, it can be asserted that these uluzzians were the first homo sapiens settling italy. despite the lack of any reliable evidence, the provenance of this population is presumably trackable from the near east, notably from its coastal belt. this corridor was traditionally considered to have been well-used by early sapiens population waves since 170 ka (herschowicz et al., 2018). in this extensive debate surrounding the modifications in human societies that occurred in concomitance with the spread of sapiens in europe, a key role is covered by the shell assemblages largely used as ornamental and symbolic objects (vanhaeren & d’errico, 2006). although neanderthals were not unaware of their use at fumane (peresani et al., 2013), the frequency of marine and freshwater shells increases considerably across early upper palaeolithic sites and in inland farther areas located great distances (taborin, 2003; white, 2004). in these sites, the lack of seashells was compensated by freshwater taxa. for instance, the open-air site of kostenki 14 yielded tens of specimens of theodoxus fluviatilis (sinitsyn, 2003). similarity in the use of marine shells has been observed during the uluzzian at both northern and southern sites, as reported at cavallo, la cala and castelcivita. at klissoura cave in greece, where intentionally perforated and/or fractured shells (cyclope neritea, columbella rustica, pecten sp., glycimeris, antalis) were discovered throughout all the uluzzian phases (arrighi et al., 2020a). specifically, antalis from cavallo cave marks similitudes with the very few specimens found at broion associated also to one theodoxus danubialis specimen (arrighi et al., 2020b). hence, the discovery of the uluzzian at fumane and broion confirms that the northern cultural frontier of this complex is an archaeological reality, which dispels doubts of its existence outside the “core” area in southern peninsula, now nullified by the discovery of colle rotondo (villa et al., 2018). furthermore, this revelation stresses the importance of the northern adriatic area as a corridor for attracting the movements of faunal and human groups from the east during the extension of landmass as a consequence of the sea-level mis3 fall. given the co-existence of neanderthals and homo sapiens for around 2,600-5,400 years in europe (higham et al., 2014) or even more (slimak et al., 2022), genetic exchange has been claimed for this period (fu et al., 2016), together with the fact that a possible transmission 192 peresani m. ois, hunted in the site surroundings in a mostly open and patchy woodland landscape under cold climatic conditions. a recent estimation of net primary productivity (npp) reflects how its fluctuations in the prealpine area, where fumane cave is located, affected the biotic resources in contrast to known mediterranean sites. nonetheless, protoaurignacians’ resilience was successful in a mosaic of environments that were affected by significant climate changes and supported rapid dispersal of human groups (marin-arroyo et al., 2023). about the lithic industry, recent studies carried out on the fumane lithic assemblages have contributed to a more precise definition of the protoaurignacian through a high-resolution inspection of the production of blades and bladelets (falcucci & peresani, 2022). this reevaluation revealed that dissociate reduction sequences were addressed to obtain bladelets within a single and continuous knapping from the same core as the result of its progressive reduction. the first goal of production was thus bladelets which did not originate from a broad range of independent core reduction strategies. an additional analysis focusing on carinated core technology furnished further evidence to the theory about a common technological background shared by the protoaurignacian and the early aurignacian (falcucci et al., 2017). in fact, the major difference with the protoaurignacian is the frequency of retouched bladelets, which are much more common in this complex. this emerging view challenges the traditional focus paid on the northern aquitaine basin and raises once again the importance of the mediterranean basin as a region worthy of consideration (gennai, 2021). furthermore, the dense stratigraphic sequence of fumane is stimulating investigations on cultural diachronic variability across the time interval framed by thesecultural units. the goal is to test if the early aurignacian with its new organic artifacts followed the protoaurignacian. data have shown that the protoaurignacian techno-typological features do not switch throughout the stratigraphic sequence and across the heinrich event 4, thus challenging the debated view that environmental deteriorations at the onset of this event explain remarkable differences detected in technologies and human adaptative systems in the early aurignacian by respect to the protoaurignacian (falcucci et al., 2020). by the other hand, the appearance of split-based points in the youngest phase of the sequence at fumane is once again an expression of extensive networks that allowed this technological innovation to spread in italy (tejero & grimaldi 2015) and across different aurignacian regions. 6.3. gravettian, early epigravettian and the last glacial maximum peopling of italy despite their biological and cultural success compared to the previous european “native” populations, upper palaeolithic homo sapiens hunter-gatherers experienced dramatic biological turnovers during the late pleistocene glacial cycle, as attested by discontinuous archaeological record (djindjian et al., 1999, bocquetappel et al., 2005). nonetheless, these last glacial maximum (hereafter lgm) human groups reacted by increasing their resilience at some middle latitudes, but also through migrating at large scale along the corridors of cultural and symbolic behaviours might had occurred between these distinctively acculturated human groups. this being the case, the neanderthal population still remained active during the onset of the uluzzian, not only in western europe with the chatelperronian technocomplex (ruebens et al., 2015), or in some eurasian confined areas like murcia in southern spain (hoffman et al., 2018), but also in corridors like the ligurian arch up to 40.5 cal ka bp (higham et al., 2014). crucially, this is an area where the uluzzian has not been recorded yet. under the light of this evidence, the uluzzian, as a behavioural system developed in southern europe, displaces an intriguing potential for investigating stimulus diffusion and other processes of knowledge transfer in this scenario of coexistence with different humans. this ignites the need to move away from the traditional dichotomy, commonly used to explain the significant cultural phenomena of this phase exclusively as products of one hominin taxon or another. 6.2. protoaurignacian in the kaleidoscopic scenario of the spread of early homo sapiens into western eurasia, the appearance of the aurignacian corresponds to one amongst the most intriguing cultural dynamics of the upper palaeolithic. thus far, research has focused on the origin and chronological expansion of this technocomplex and its arrival to different regions, regardless of the climate and ecological conditions faced by the new incomers (nigst et al., 2014; shao et al., 2021). the homo sapiens populations progressively settled following eastern-northern mediterranean and central-european trajectories (hublin, 2015; mihailović, 2020), bringing with them the diffusion of the new cultural traits represented by portable and cave art, musical instruments (not in italy, yet) and evidence of use of specific categories of symbolic objects for personal purpose, even peculiar of italy (martini, 2007; arrighi et al., 2020; sigari, 2022). for instances, marine shells, collected and modified for making ornaments are one further evidence in support of past human communication behaviour and cultural exchange during this early upper palaeolithic phase (vanhaeren & d’errico, 2006). despite the paucity of marine and freshwater shell assemblages of similar age and composition in southern europe, shells from fumane, bombrini, mochi, castelcivita, partly smeared with red ochre, confirm similarities in the taxonomic composition (peresani et al., 2019; arrighi et al., 2020a). among these elements, shells of homalopoma sanguineum probably played a fundamental role in maintaining a communication system over a large geographic area. they might have represented group consciousness or even longstanding ethnic identities between the rhone basin and the eastern mediterranean regions (vanhaeren & d´errico, 2006; nitu et al., 2019). early modern humans’ subsistence strategies were successful for their dispersal throughout italy despite the mis3 abrupt climatic oscillations and the uneven topographic and ecological conditions. in northern italy one of the first european regions where aurignacians settled (frouin et al., 2022), archaeozoological data indicate seasonal site occupations during late spring/summer. the exploitation was mostly oriented on ibex and cham 193 adaptations and cultures of pleistocene humans in italy connecting european regions. demography and behaviour were thus deeply affected, resulting in the synchronic and diachronic development of a variety of archaeological cultures in different regions and at different times. for this reason, the timing and pattern of multiscalar shifts that occurred from the lgm to the onset of the late glacial (hereafter lg) interstadial (14.7 cal ka bp) are considered among the most important events, also in italy. before 30 ka bp in the alps, glaciers were already growing and reached their maximum extent around 25.0±1.7 cal ka bp (monegato et al., 2017). despite these geographic and climate changes (antonioli & vai, 2004), in southern europe several regions experienced the development of open boreal forests and highly productive wetlands thanks to more favourable conditions supporting (badino et al., in press) which also helped the survival of several mammal species (svenning et al., 2008): here they could thrive while large part of their former distribution areal, in central and northern europe, was covered by ice sheets. in turn, hunters-gatherers groups’ subsistence was favoured by the presence of a rich mammal fauna in these southern refugial areas in turn gave subsistence to hunters-gatherers groups enhancing their capability to maintain large-scale networks (soffer & gamble, 1990; djindjian et al., 1999; moreau, 2009) as attested also by large scale distribution of homalopoma sanguineum shells in the balkans (nitu et al., 2019). as a matter of fact, south of the alpine chain, more favourable conditions allowed the survival and delayed extinction of important consumers like cave bears (terlato et al., 2019a). nonetheless, a full understanding of the way upper palaeolithic groups modulated their biological, cultural and social adaptation to the late pleistocene climate change is still far from being achieved, especially in regions of strategic importance for their geographic position, geomorphological setting and biodiversity. the reason is also due to the low number of archaeological sites that have been radiocarbon-dated to the lgm: these are in western liguria, in the northern and northeastern fringes of the po valley, along the thyrrenian coast and, to the east, in apulia (palma di cesnola, 2001; mussi, 2001) (fig. 3). all of them are either caves or rockshelters, since only one open-air settlement has been excavated so far (mussi & peresani, 2004): these are the piovesello and bilancino sites on the apennine range. at piovesello, a site situated on the watershed of the northern apennine (peresani et al., 2018), unexpected archaeological evidence dated to gs-5 was recovered proving that open, extreme landscapes were the edge of elevational logistical movements of human groups along mountain ecozones. bilancino is a specialized site excavated on a fluvial terrace of the western slope of central apennine (aranguren & revedin, 2008). acquisition strategies of lithic raw materials hint for a well-established territory extended from the central tyrrhenian coasts to across the mountainous chain towards umbria or marche regions, where chert outcrops provided a relevant amount of knappable stone (aranguren et al., 2015). overall, this patchy gravettian archaeological record in italy is to some extent the result of a lack of scientific investigation (palma di cesnola, 2001). site size is also different in the two better investigated areas. some substantial or even large sites are known at sea level in liguria at the balzi rossi. grotta arene candide, further east, is possibly another major site. in southern italy, evidences of human occupation are very scarce in number indeed. grotta paglicci witnessed traces of repeated frequentations and human burials across its long-stratified deposits, thus becoming a reference cultural complex site (palma di cesnola, 2004). following the aurignacian, the gravettian technotypological signatures spread in a rather short time interval across europe (reynolds & green, 2019) and also italy. here, the earliest known gravettian assemblages at the edge of the great po plain are dated at fumane to ca. 35-34 cal ka bp and slightly later at paglicci cave in the southern adriatic region (palma di cesnola, 2004; talamo et al., 2014; falcucci & peresani, 2019). the early gravettian appears in italy to be more homogeneous than the later stages of this technocomplex, being characterized by the presence of backed points and the absence of other typical tool types. after this phase, the adriatic and tyrrhenian records took different cultural trajectories: noailles burins were designed, manufactured and used in western italy as a result of cultural contacts between adjacent regions (santaniello & grimaldi, 2019), but they are missing in the archaeological record of adriatic italy and the balkans (mihailovic & mihailovic, 2007). a key region for human and animal migrations was the great adriatic-po plain (gapr). this vast continental shelf emerged as consequence of the lgm sea level low stand, extending from the western balkan peninsula to peninsular italy (peresani et al., 2021). this area is a paradigmatic case, thanks to its peculiar geographic setting and climatic and ecological variability, which supported refugia for temperate species and witnessed vast movements of populations. the human adaptive flexibility expressed by the gravettian-epigravettian material culture, human mobility, subsistence and symbolic thinking from this region has been the focus of multidisciplinary investigations. in the last decade new paleo-geographic, ecological and anthropogenetic data were obtained from a large set of sources circumscribing the gapr, including the italian prealps, to boost our understanding of the settlement dynamics. summarizing, cultural and petroarchaeometric evidence of chert tools reveal the existence of large-scale circulation patterns across the gapr of finished or semifinished early epigravettian artefacts made of chert coming from the formations of the umbria-marche apennines in the subalpine zone, istria and dalmatia, thus pointing to the gapr as a suitable land for gravettian and epigravettian hunter-gatherers. this point of view was questioned several times since the end of the 80’s of the 20th century. some contrasting positions supported at times the view of a plain seasonally crossed by large migratory herbivores, thus rich in game, water and a variety of resources, especially along water courses, across ecotones, around lakes and on the coastal and estuarine environments. under this light the plain has become more attractive for human populations than the karstic inland, sporadically settled on a strictly seasonal basis and careful planning (peresani et al., 2021, and refer 194 peresani m. middle gravettian are too sparse in the gapr to reconstruct the settlement dynamics in this landscape, a marked trend in the design and circulation of chert artefacts has been highlighted starting with the late gravettian-early epigravettian and up to the early late epigravettian (peresani et al., 2021). this event coincided with a renewal in hunting weaponry around 24 cal ka bp, mainly consisting in the introduction of shouldered points rather than other backed implements. the longence therein). connections between sites located over 250 km apart from another do not contradict the scenario drawn in the innermost continental europe, when hunter-gatherers inhabited with variable continuity cold, cold-temperate and often moister biomes. at the edge of the gapr, stable terraces along the apennine belt were potential areas to settle on a seasonal base or maintain a network of exchanges between different groups. although data about human mobility during the 195 fig. 3 key upper palaeolithic sites in italy: 1) grotte di pradis; 2) altopiano del cansiglio; 3) riparo villabruna; 4) riparo dalmeri; 5) riparo del broion; 6) covolo di trene e grotta di paina; 7) grotta di fumane; 8) riparo tagliente; 9) balzi rossi; 10) grotta della basura; 11) arene candide; 12) piovesello; 13) bilancino; 14) grotta la fabbrica; 15) fosso mergaoni e grotta della ferrovia; 16) fonte delle mattinate; 17) grotta polesini; 18) colle rotondo; 19) grotta paglicci; 20) serino; 21) grotta di castelcivita; 22) grotta della cala; 23) grotta della serratura; 24) grotta del romito; 25) grotta di santa maria di agnano; 26) grotta del cavallo e grotte della baia di uluzzo; 27) grotta delle veneri; 28) grotta romanelli; 29) grotta san teodoro; 30) grotta dell'addaura (source http://tinitaly.pi.ingv.it; elab. by d.delpiano).. adaptations and cultures of pleistocene humans in italy range circulation of these points encompasses several macro-regions of europe and could be related to new mobility strategies or changes in human groups and their way of exploiting resources in this territory. around 24 cal ka bp, the early epigravettian replaced the former technocomplex in coincidence of the gi-2, a climatic threshold marking major cultural changes in western eurasia (ruiz-redondo et al., 2022). extensive renewals in the variety of marine species used as ornaments are recorded only during the late epigravettian, hence leaving incertitude on a wide chronological range (martini ed., 2007). paleogenetic studies focusing on gravettian and post-gravettian hunter-gatherer individuals, combined with fine resolution radiocarbon chronologies and cultural data allow a better comprehension of the population dynamics that accompanied modern human reexpansion towards the end of the lgm. specifically, biomolecular data reveal that several population transformations took place across europe, with reduced diversity in mtdna during the lgm, but also survival of european maternal gene pool (fu et al., 2016; posth et al., 2016). in this scenario, a population turnover took place around 18 cal ka and well before the lg interstadial, as revealed from genetic discontinuity due to the spread of individuals of the villabruna cluster (an individual retrieved in riparo villabruna, dated to 14.2-13.8 cal ka bp; aimar et al., 1992), sharing distinctive affinity to present-day populations from the near east. additional genome-wide data have been achieved from the analysis of the individual from riparo tagliente, so essential to understand the distribution of such ancestry through time in southern european climatic refugia (bortolini et al., 2021). this incoming genetic component largely replaced the ancestry identified also in older magdalenian-related individuals from central europe (fu et al., 2016) and supports the hypothesis that, from at least 19 -18 cal ka bp, european populations were broadly interconnected across the gapr and beyond. 6.4. late-glacial, the submersion of the gapr and the spread of epigravettian hunter-gatherers after the last glacial maximum, the changes of vegetation and animal distribution viewed the peopling of italy as a gradual process marked by the progressive colonization of new territories following (naudinot et al., 2014; vescovi et al., 2017) and coinciding with the spread of the epigravettian. this cultural complex consists in an ensemble of industries following the gravettian until the end of the pleistocene. as stated above, the reaction of human groups to the lgm physical and ecological turnovers deeply contributed to the shaping of our present genetic ancestry. in the gapr, the end of the lgm lgm witnessed, also in lowlands, quick geomorphological changes due to the corresponding collapse after 18 cal ka bp of the alpine glaciers, starting their final withdrawal. the effects of these modifications on human occupation along river terraces in the plain are not yet detectable. conversely, at the northern edge of the gapr in the prealpine foothills, riparo tagliente was a location persistently settled by human groups for the exploitation of local biotic and abiotic resources which marks one of the first steps of the pioneering colonization of the inner mountain belt on relatively stable areas (fontana et al., 2009). evidence of this phase is however scanty. such scarcity of data hampers the reconstruction of the peopling of the italian eastern alps and dinarides triggered by the climatic amelioration of the lg interstadial starting at 14.7/14.5 cal ka bp. in the lg interstadial, the progressive rise of the adriatic coastline combined to the expansion of the treeline up to 1700-1800 m a.s.l. in the se-alps (vescovi et al., 2007) are among the key factors leading human groups to intensely occupy the interior mountain ranges along new routes and to expand their settlements (bertola et al., 2007; naudinot et al., 2014) (fig. 3). late epigravettian penetration, firstly limited to valley floors and high plateaus around 500 m above modern sea level (amsl), reached mid-altitude territories during the second part of the lg interstadial with the full development of a logistical occupation network at the ecotone between coniferous woods and alpine prairies (bertola et al., 2007). this organisation corresponds to a seasonal mobility strategy based on sites that are functionally complementary to each other and located at different altitudes. regarding the faunal target, the most exploited game was ibex, which is the dominant species in dalmeri rock shelter and other midaltitude sites (tagliacozzo and fiore, 2000), alongside with marmots, systematically exploited in the pradis plateau (romandini et al., 2012; nannini et al., 2022). lithic industries evolved towards a progressive simplification of the production systems, associated with the persistence of standardized lithic backed tools used as projectile implements in response to specific functional requirements and constraints (duches et al., 2018; montoya et al., 2018). other than the alpine slope, the general increase of evidence and radiocarbon datataset at the beginning of the greenland interstade 1 (gi-1), has been interpreted as the result of a major change in the socio-economic system of epigravettian groups. changes in lithic technology occurred during this period are likely to be associated with some major modifications of the mobility patterns with clear increase of task-oriented sites and a global multiplication of the sites. evidence is sparse all over italy, but morefrequent in the ligurian arch, eastern alps, northern and central apennine, sicily and patches along the thyrrenian and adriatic coasts. in liguria, an exceptional ichnosite is the cave of básura near toirano, where about thirty footprints dated to 14 cal ka bp are referred to a small group of visitors (avanzini et al., 2021). the pleistocene-holocene transition also marked a major turnover in the history of the environment and prehistoric peopling of high latitude regions as much as mountain territories. after the gi-1, the progressive decrease in temperatures in coincidence of the greeenland stade 1 (gs-1: 12.9-11.7 cal ka bp), gave rise to a set of modifications with which the hunter-gatherers related. the spread of hunter-gatherers is recorded with variable details in the alps, the eastern sector, and the central apennine, which were the scenarios of extensive research on human occupation since the 1970’s. the archaeological record shows a relative scarcity of sites with evidence of gs-1 occupation, contrasting with the 196 peresani m. references agam a., barkai r. 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(2015) analysis of site formation and assemblage integrity does not support attribution of the uluzzian to modern humans at grotta del cavallo. plosone 10(7), e0131181. ms. received: march 2, 2023 revised: may 23, 2023 accepted: may 24, 2023 available online: may 27, 2023 204 peresani m. ojs 633 iannucci et al gm as.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 35 (2), 2022, 1-13 1. introduction hyenas were once an ecologically diverse group that showed adaptations to many different feeding behaviors, from the probable insectivory/omnivory of civetlike and mongoose-like species, to hypercarnivory and “bone-cracking” (kurtén, 1956; howell & petter, 1980; werdelin & solounias, 1991, 1996; semenov, 2008; turner et al., 2008; tseng et al., 2013; coca-ortega & pérez-claros, 2019; koufos, 2021; iurino et al., 2022; lewis & werdelin, 2022). the latter is almost the only ecomorphotype (or ecomorph; werdelin & solounias, 1996) that survived to the present day. indeed, with the exception of the aardwolf, proteles cristatus (sparrmann, 1783), which is a specialized termite eater (kruuks & sands, 1972; cooper & skinner, 1979), the other three living hyenas, crocuta crocuta (erxleben, 1777), hyaena hyaena (linnaeus, 1758), and parahyaena brunnea (thunberg, 1820), display a suite of craniodental traits that highlight their ability of cracking bones. this capacity gave bone-cracking hyenas access to resources out of reach of most other predators and scavengers, apart mainly from hominins, who could also crack and deflesh bones using tools. therefore, quaternary hyenas are often considered as potential competitors of hominins, stimulating research with vibrant paleoecological and taphonomic implications, but also engendering debate on the magnitude of homohyena interactions and relationships (stiner, 1991; turner & antón, 1996; boaz et al., 2000; lewis & werdelin, 2010; espigares et al., 2013; madurellmalapeira et al., 2017; iannucci et al., 2021b). an interesting period on which our knowledge on the evolution of hyenas is still rather imperfect is around 2.0–1.8 ma. at the time, the giant hyena pachycrocuta brevirostris (gervais, 1850) spread into europe, becoming soon after the only bone-cracking carnivoran for most of the early pleistocene (iannucci et al., 2021b). in some of the earliest localities where p. brevirostris is recorded, the giant hyena is accompanied by other species that will be no longer present in later faunas, namely the hunting hyena chasmaporthetes lunensis (del campana, 1914) and another bone-cracker, pliocrocuta perrieri (croizet & jobert, 1828). chasmaporthetes lunensis is a more gracile and cursorial species than the others, and its ecology is often discussed in comparison to carnivorans other than bone-cracking hyenas (kurtén & werdelin, 1988; ferretti, 1999; antón et al., 2006; tseng et al., 2011, 2013; pérez-claros et al., 2021; konidaris, 2022; marciszak et al., 2022). conversely, https://doi.org/10.26382/amq.2022.06 the lost hyena from paciano (umbria, italy) reconsidered. alessio iannucci 1, marco cherin 2, raffaele sardella 1 1 dipartimento di scienze della terra (paleofactory lab.), sapienza università di roma, roma, italy. 2 dipartimento di fisica e geologia, università degli studi di perugia, perugia, italy. corresponding authors: a. iannucci <alessio.iannucci@uniroma1.it> abstract: we redescribe and revise the taxonomic attribution of a lost hyena hemimandible recovered from paciano (umbria, italy), originally reported in the early 1900s, by comparing it with relevant samples of pliocene, pleistocene, and extant species. the mandible of the paciano hyena was initially attributed to hyaena striata (= hyaena hyaena) and subsequently listed as a record of the giant hyena pachycrocuta brevirostris, but is here assigned to another “bone-cracking” hyena, the pliocene-early pleistocene pliocrocuta perrieri. the paciano hyena contributes to the discussion on the relationships and turnover between pl. perrieri and p. brevirostris. on the one hand, the two species are very similar in craniodental morphology; their isolated remains are often separated by size; and p. brevirostris is thought to derive from a large-sized population of pl. perrieri. on the other, a larger size is not an aspect to disregard in hyenas as it usually correlates with the acquisition or better development of “bone-cracking” features; remains attesting the co-occurrence of pl. perrieri and p. brevirostris are known from some sites dated at around 2.0–1.8 ma; and the observed size differences between the two species exceed those recorded between extant and (at times) sympatric species. therefore, taken alone the competition with p. brevirostris does not explain the extinction of pl. perrieri, but considering it together with the concurrent spread and resulting peak of carnivoran diversity in late villafranchian faunas might. pliocrocuta perrieri was outcompeted by its larger descendent in scavenging carcasses, while other carnivorans limited its options to deviate to other resources or adopt a different feeding behavior (e.g., active hunting). the case of paciano is also significant in that it offers an example of the importance and feasibility of reconsidering historical collections, even when the original material is lost entirely. in general, the seek for “novelty” that permeates current scientific literature ensues in few descriptions or reconsiderations of historical samples, especially if the new examinations confirm old results, but we emphasize the significance of such efforts in making old data truly available for the scientific community. in addition, the hyena from paciano has a biochronological and stratigraphic value, confirming the occurrence in western umbria of a depositional cycle older than the late early pleistocene one (well represented by the rich assemblages from pietrafitta and selvella; farneta faunal unit). keywords: hyaenidae, carnivora; quaternary; europe; historical collections. 2 iannucci a. et al. pliocrocuta and pachycrocuta are considered ecomorphologically very close and indeed placed by some authors in the same genus (e.g., qiu et al., 2004; liu et al., 2021). arguments in favor of a “sharp” separation between pliocrocuta and pachycrocuta are some morphological differences, especially the lack of a metaconid in the lower carnassial in p. brevirostris (werdelin & solounias, 1991) and the co-occurrence of the two species in some european localities at ~2.0 ma (iannucci et al., 2021b). on the other hand, localities where hyaenid fossils have been assigned to both species are not but a few, and attributions are merely based on the size of the remains (iannucci et al., 2021b). from an ecological point of view, the increase in size in hyenas is nonetheless significant, as it is generally correlated to the acquisition or better development of “bone-cracking” craniodental features (werdelin & solounias, 1991). moreover, despite the paucity of available remains in relevant localities, the reliability of such size-based repartition would be corroborated by the low level of sexual dimorphism –in craniodental measurements– observed in c. crocuta (e.g., garcía, 2003; lewis & werdelin, 2022), assuming that the same holds true for pliocrocuta and pachycrocuta. in general, the spotted hyena is definitely the most studied amongst extant hyenas (e.g., kruuk, 1972; frank, 1986a, b; kolowski et al., 2007; holekamp et al., 2012), somehow “skewing” considerations on hyenas as a whole (werdelin & solounias, 1991; lewis & werdelin, 2022). however, considering how many aspects of c. crocuta biology and ecology are regarded as peculiar in comparison to other extant bone-cracking hyenas (e.g., kruuk, 1972; frank, 1986a, b; mills 1982, 1990) and that it has been suggested that several features might have evolved recently (werdelin & lewis, 2008), it remains to be answered to what extent similar characteristics were present in extinct hyenas (iannucci et al., 2022). in this framework, there is a critical need of description of more material that might be key to clarify. notwithstanding the importance of the recovery of further fossils from new excavations, revising historical collections might also offer new insights. the rediscovery of important specimens or new research in old localities is often the impetus for revising historical collections (e.g., bona, 2021; fabbi et al., 2021; mecozzi et al., 2021, 2022), but reconsiderations of many samples are never attempted, especially if represented by few specimens. the number of “sporadic” findings, that is, those fig. 1 geographic location of paciano (red star). the extensional basins cited in the text are highlighted. 3 the lost hyena from paciano not recovered during systematic excavations, can be substantial in localities with a long research tradition and/or when fossiliferous formations span vast areas (e.g., argenti, 2004; iannucci et al., 2021c; mecozzi et al., 2021). extensive fossil samples remain undescribed in museums and other institutions, which might be seen as a particular case of the “taxonomic impediment” (rodman & cody, 2003) in one of its worst forms, that is, not necessarily due to the lack of proper expertise, but to the poor motivation to undertake dedicated studies, given the long effort needed and the meager credit taxonomic and descriptive works might have (godfray, 2002; agnarsson & kuntner, 2007). in several cases, historical samples were the subject or works carried out at the time of their discovery, but then went entirely lost or destroyed for disparate reasons. notorious incidents that caused immeasurable loss of natural history collections span from the bombing of several museums and institutions during world war ii (e.g., crumly, 1984) to the recent fire of the national museum of brazil in 2018 (escobar, 2018). implications for such losses are huge, and the existence of historical descriptions can have great importance from purely taxonomic and nomenclatural considerations to all that follows (e.g., pape et al., 2018). paradoxically, however, the existence of previous works also adds further difficulties in offering stand-alone reconsiderations of historical samples, as they might be perceived as not original, the seek for “novelty” being a key aspect of current scientific publication practice (makel & plucker, 2014). in this context, umbria (central italy) represents an emblematic case. in fact, despite the small geographical extension but thanks to the considerable (vertical and horizontal) development of plio-pleistocene sedimentary basins on the territory, it has played and still plays a key role for the understanding of the faunal turnovers that occurred in the last 3 ma or so (cherin, 2013). the historical collections of fossil mammals from umbria have been known to science since the beginning of the 19th century (e.g., cuvier, 1821) and were often the preserve of nobles or other prominent personalities of culture and society (as was the case in many other parts of europe at that time). the recent reconsideration of some of these collections or of individual fossils has led to interesting knowledge advances. for instance, the revision of part of the mammal assemblage (cicioni and bellucci collections) recovered from villa spinola (perugia) in 1894-95 (tuccimei, 1895) led to the description of the only partial skeleton of the felid panthera gombaszoegensis (kretzoi, 1938) known in umbria to date (argenti & sardella, 2003). similarly, a recently reappraised mandible of tapirus arvernensis croizet & jobert, 1828 from the lignite mines of spoleto (clerici collection; clerici, 1895) was recognized as the southernmost record of this species in italy (pandolfi & kotsakis, 2017). here, we redescribe and revise the taxonomic attribution of a lost hyena hemimandible recovered from paciano (umbria, italy; fig. 1), originally reported by bortolotti (1905), comparing it with relevant samples of pliocene, pleistocene, and extant species. 2. materials and methods the original hyena right hemimandible recovered from paciano and described by bortolotti (1905) is apparently lost, as reported by argenti (2004) when listing fossil localities of umbria and as confirmed by our own surveys in relevant institutions. in detail, the paciano hyena was part of the ancient canali collection, a historical collection that went lost after the first decades of the last century (argenti, 2004). only a fraction of the canali collection is still curated in the regional direction for museums of umbria, including some other specimens described by bortolotti (1904). nonetheless, even if the original material is not available for direct examination, bortolotti (1905) provided measurements and comments that allow to compare and contextualize this important specimen in an updated taxonomic framework. bortolotti (1905) attributed the paciano hyena to hyaena striata (= hyaena hyaena), while argenti (2004) referred it to p. brevirostris. however, iannucci et al. (2021b) did not mention paciano among the occurrences of the giant hyena. the massive and straight mandibular corpus of the hyena from paciano adheres in morphology to that of a bone-cracking hyena. therefore, the mandible was compared with that of extinct and extant bone-cracking hyetab. 1 measurements (in mm) of the hyena right hemimandible from paciano provided by bortolotti (1905). l = length, w = width, m1 pa-pr = distance between paraconid and protoconid, m1 bhpa = buccal height of the crown at the paraconid, m1 bhpr = buccal height of the crown at the protoconid, m1 hmt = height of the crown at the metaconid, di = length of diastema c1-p2, c1 -m1 = inclusive length of c1-m1, p2-m1 = inclusive length of p2m1, hfp2 = dorsoventral height of the mandible in front of p2, hbm1 = dorsoventral height of the mandible behind m1, tpl = total preserved length of the mandible between the base of c1 and the rear of the ascending ramus. 1 approximate value according to bortolotti (1905). 2 we also consider these values approximations, as bortolotti (1905) reported that the tooth was fragmented above the base of the crown. 3 the true total length of the mandible would have been greater than the reported value. interno del ferino” (= “internal tubercle of the carnassial”; own translation from the original italian)] and a welldeveloped talonid hosting two cuspids (one buccally and one lingually) separated by a valley. 3.2. biometric comparison the results of the pca are consistent with those obtained by iannucci et al. (2021b). in logpca, the morphospace projection onto the first two components (figure 3) separates specimens mainly according to their size (along pc1, 86.5% of explained variance) and relative elongation of m1 (along pc2, 8.6% of explained variance). the large-sized p. brevirostris is placed on the right of the scatter plot and c. crocuta separated towards positive values on pc2. the other species are grouped on the left and are mainly, but not completely (apart from h. hyaena and “h.” prisca), distinct by size. some specimens of pl. perrieri, especially that from paciano, plot towards positive values along pc2, meaning they have relatively elongated m1. when the effect of size is adjusted in gmpca, the morphospace projection of the first two components (figure 4) separates specimens mainly on the base of the elongation of m1 (along pc1, 66.0% of explained variance) and the proportions of the premolars (along pc2, 21.4% of explained variance). the latter differences are mainly intraspecific and place specimens with widened premolar towards more negative values along pc2. basically, in gmpca only c. crocuta clearly occupies a distinct area of the morphospace, while there is overlap between all other species. also in this case, there are, however, few specimens of p. brevirostris and pl. perrieri, especially paciano, that plot closer to values observed for c. crocuta, having relatively elongated m1. detailed bivariate comparisons of length and width of each tooth confirm the differences in size observed with the pca (figure 5). hyaena hyaena is the smallest species in all considered measurements, while p. brevirostris is the largest in all but m1 l, in which it is surpassed by several specimens of c. crocuta. in terms of dental proportions, all species are similar, apart from c. crocuta, which is almost completely separated by other hyenas according to its relatively more elongated m1 (figure 5c). in general, measurements of the hemimandible from paciano place it among small-sized specimens. in detail, in the p3 scatter plot it falls within the ranges of h. hyaena and pl. perrieri, and not far from the smallest specimens of brown and spotted hyenas nas, namely pl. perrieri, p. brevirostris, c. crocuta, “hyaena” prisca, h. hyaena, and pa. brunnea. the sample from longdan (qiu et al., 2004), considering his potentially “transitional” position between pliocrocuta and pachycrocuta (iannucci et al., 2021b), is analyzed separately. length (l) and width (w) of third premolar (p3), fourth premolar (p4), and first molar (m1) were included in the analysis. here, the choice of variables was dictated by the availability of reliable measurements provided by bortolotti (1905), but previous biometric analyses similarly relied on the p3-m1 series (iannucci et al., 2021b). we used the dataset assembled by iannucci et al. (2021b), with the addition of the paciano specimen, as the input for two pca analyses on the variance-covariance matrix of the considered measurement, in the first case using log-transformed values (referred to as logpca in the text) and in the second “size-adjusting” raw measurements by dividing them by the geometric mean (gmpca) of all measurements for that specimen (mosimann, 1970; mosimann & james, 1979; jungers et al., 1995), the latter being an effective method to produce dimensionless variables widely adopted in studies on fossil mammals (e.g., ercoli et al., 2019; iannucci et al., 2021a). the software past version 4.04 (hammer et al., 2001) was used for the analysis. to avoid confusion when referring to different taxa, pachycrocuta is abbreviated to p., pliocrocuta to pl., and parahyaena to pa., when appropriate. measurements of the paciano hyena and related abbreviations are provided in table 1. 3. results 3.1. description bortolotti (1905) provided only a figure of the paciano right hemimandible, from which the morphology of the dentition is not very clear (fig. 2). still, the robust and straight corpus of the hemimandible is indicative of a bone-cracking hyena, similar in proportions to all species considered in the comparison except for c. crocuta, in which the body is shallower near the symphysis (palmqvist al., 2011; iannucci et al., 2022). according to bortolotti (1905), the mandible of paciano preserved the right p3-m1 series, with p2 and c1 also present but severely damaged. the author did not provide many details in his description of the specimen, but he emphasized the presence in m1 of a metaconid [“tubercolo 4 iannucci a. et al. fig. 2 the hyena right hemimandible recovered from paciano. modified from bortolotti (1905). fig. 3 scatter plot (a) and loadings (b) of the first two principal components of logpca. for raw data and detailed references, see iannucci et al. (2021b). 5 the lost hyena from paciano fig. 4 scatter plot (a) and loadings (b) of the first two principal components of gmpca. for raw data and detailed references, see iannucci et al. (2021b). 6 iannucci a. et al. 7 the lost hyena from paciano fig. 5 bivariate plots comparing l and w (in mm) of p3 (a), p4 (b), and m1 (c) of the hyena from paciano and several samples of extinct and extant bone-cracking hyenas. 8 iannucci a. et al. (figure 5a). in the bivariate comparison of p4 measurements, paciano is somewhat distinct from other species but closer to c. crocuta (figure 5b). considering length and width separately, in p4 l, paciano is compatible with c. crocuta, h. hyaena, pa. brunnea, and pl. perrieri, while p4 w only fits with h. hyaena and smallest values of c. crocuta. in m1 measurements, paciano again does not plot confidently in the range of one of the groups of the comparative sample, but it is close to specimens of c. crocuta, pa. brunnea, and pl. perrieri. 4. discussion bortolotti (1905) attributed the paciano hyena to h. striata (= h. hyaena), noting an overall resemblance with h. arvernensis (= pl. perrieri) but judging the specimen too small to belong to that species. indeed, our comparisons showed that there is some overlap, though limited, between the largest specimens of h. hyaena and the smallest of pl. perrieri in most measurement considered (figure 5). however, although the paciano hyena is apparently among the smallest specimens of pl. perrieri, it has a larger and proportionally more elongated m1 than that of h. hyaena, which separates it from this species. this evidence allows to identify the paciano hyena as pl. perrieri. considering the paucity of comparative material bortolotti (1905) had in his disposal, his taxonomic opinion represented the best fit for the then available evidence, but can now be confidently revised. pliocrocuta perrieri and the giant hyena p. brevirostris have a very similar morphology, and remains of the two species are often separated by size (iannucci et al., 2021b). in this respect, the small size of the paciano hyena clearly excludes an attribution to p. brevirostris, which was tentatively suggested by argenti (2004). bortolotti (1905) also underlined the presence of a welldeveloped metaconid in the m1 of the paciano hyena, a feature that reinforces its assignment to pl. perrieri (werdelin & solounias, 1991; iannucci et al., 2021b). in some measurements, the paciano hyena seems peculiar in comparison to other specimens of pl. perrieri. in detail, the p4 w (11.5 mm) is slightly below the minimum value of the sample of pl. perrieri included in the comparison (12.1 mm), although not outside the range known for the species (a minimum value of 9.3 mm is reported by coca-ortega & pérez-claros, 2019). moreover, although the specimen is small in most measurement, the value of m1 l is relatively high, denoting a proportionally elongated carnassial. however, considering the fragmentary nature of the specimen and that bortolotti (1905) evidently adopted a “coarse” approximation at 0.5 mm in his measurements, the observed differences are likely spurious. for completeness, it is worth mentioning that a reference of the paciano hemimandible to c. lunensis, a species that might have been compatible with the putative age of the fossil locality, is clearly discouraged by morphological and biometric traits, including the robust and straight mandibular corpus, the presence of a metaconid in m1, and the widened teeth, among others (werdelin & solounias, 1991; tseng et al., 2013). the presence of pl. perrieri at paciano has also implications for the age of the fossil deposit. the latest occurrences of pl. perrieri in europe are dated at ~2.0– 1.8 ma (iannucci et al., 2021b), and the species is certainly more abundant in older localities (e.g., viret, 1954; howell & petter, 1980; qiu, 1987; werdelin & solounias, 1991). in umbria, most plio-pleistocene mammal assemblages have been discovered within the tiberino basin, which extends across the center of the territory for ~1800 km2 (cherin et al., 2019). other findings are reported from the smaller tavernelle-pietrafitta basin, south of lake trasimeno, including the extremely rich assemblage from the pietrafitta lignite mines (martinetto et al., 2014; sorbelli et al., 2021, and references therein). finally, some other mammal remains have been recovered from the valdichiana basin, whose deposits crop out in few areas of western umbria (figure 1). among the latter discoveries, it is worth mentioning the assemblages from selvella and vigna nuova. the former was originally dated at ~1 ma (de giuli, 1987), but then referred to the farneta faunal unit (fu; ~1.5 ma; alberdi & palombo, 2013; cirilli et al., 2020), similarly to the aforementioned assemblage from pietrafitta. the case of vigna nuova is intriguing because taphonomic and geological evidence have allowed the sample to be divided into two assemblages (azzarà et al., 2022). the younger, including only remains of cf. leptobos collected from conglomerates (“upper layer”), can be correlated with other well-known valdichiana assemblages (e.g., selvella, farneta), thus dated at ~1.5 ma. the older sub-sample, coming from a putative paleosol (“lower layer”) no longer visible in the field, includes cf. megantereon, canis sp., mustelidae indet., proboscidea indet., equus cf. senezensis, cf. leptobos, croizetoceros ramosus, pseudodama sp., cervidae indet. (large size), and sus cf. strozzii. azzarà et al. (2022) referred this assemblage to the coste san giacomo fu (late middle villafranchian; ~2.2–2.1 ma). unfortunately, the exact provenance of the hyena from paciano is unknown. on the basis of the geographical location of the municipality of paciano (figure 1), the fossil could come from deposits of either the valdichiana or tavernelle-pietrafitta basin. therefore, given that the last occurrence of pl. perrieri is attested at the beginning of the late villafranchian (but the species is certainly more abundant in europe in the middle villafranchian), its presence in paciano could (1) confirm the presence of a late middle villafranchian sedimentary cycle in the valdichiana basin, in agreement with the recent discoveries at vigna nuova (azzarà et al., 2022) or (2) suggest the presence of a similar sedimentary cycle also in the tavernelle-pietrafitta basin, not reported so far. unfortunately, as it is not possible to define whether the fossil comes from one or the other basin, this doubt cannot be resolved. the paciano hyena likely falls in a time-span of great interest for the evolution of hyenas in europe, when some localities still document the presence of c. lunensis and pl. perrieri, but also the contemporaneous occurrence of p. brevirostris (iannucci et al., 2021b). if the coexistence between c. lunensis and the other species is easily justifiable by their different inferred ecology (e.g., werdelin & solounias, 1991, 1996; tseng et al., 9 the lost hyena from paciano 2011, 2013), that between pl. perrieri and p. brevirostris might seem to necessitate some further explanation, as they are very similar in craniodental morphology. a somewhat similar case that is worth considering here is the extinction in europe of p. brevirostris. after ~1 ma since its appearance in the european fossil record, the rule of the specialized bone-cracker came to an end close the early-middle pleistocene boundary, ~0.8 ma, approximately coinciding with the arrival of c. crocuta and “h.” prisca (iannucci et al., 2021b). competition between p. brevirostris and c. crocuta has often been advocated as a factor potentially favoring the disappearance of the former (e.g., kurtén, 1968; palombo et al., 2008). iannucci et al. (2021b) argued instead that the newcomers hardly played a significant role in the extinction of p. brevirostris, considering paleoecological and paleobiogeographical aspects, but mostly revising the putative records previously deemed to attest a persistence of the giant hyena in europe beyond the earlymiddle pleistocene boundary and its coexistence with c. crocuta. the authors also reasoned that although the error ranges associated with the available dating estimates for the last occurrences of p. brevirostris and the firsts of c. crocuta in the iberian peninsula do not allow to exclude an overlap in the chronological range of the two species –one of the aspect that might permit to hypothesize some sort of competition– from a biochronological point of view the arrival of galerian newcomers such as cervus elaphus, sus scrofa, and c. crocuta at gran dolina and cueva negra (earliest localities with c. crocuta) likely supports a separation from vallparadís evt7 (latest calibrated occurrence of p. brevirostris). this remark has now received further support from the revised chronological constraints for the lower levels of gran dolina (duval et al., 2022), which, among the other things, are incompatible with the previous paleomagnetic correlation for the normal polarity intervals of the unit td7 with the kamikatsura (846 ± 10 ka) and/or santa rosa (932 ± 5 ka) magnetic excursions (parés et al., 2013). the new dating constraints rather point to a correlation with the matuyama-brunhes precursor, which is not older than 794 ± 4 ka but perhaps even younger (channell et al., 2020; haneda et al., 2020; duval et al., 2022). the previous interpretation was the main reason to consider c. crocuta potentially present in europe prior 0.9 ma (e.g., martínez-navarro, 2010; palombo, 2014), as td7 overlies levels with hyaenid remains in the sequence of gran dolina. therefore, the “c. crocuta event”, as it is often referred to (martínez-navarro, 2010), likely occurred ~0.8 ma. this age is close to the earliest occurrence of c. crocuta in italy from the layer of gravels and sands of cava di breccia di casal selce, which is dated around 0.75–0.70 ma and yielded the reference fauna of the ponte galeria fu, at the beginning of the galerian european land mammal age (petronio & sardella, 1999; sardella & petrucci, 2012; strani et al., 2022). in this case, competition between hyenas hardly played a significant role in the extinction of p. brevirostris, although it might have influenced the late dispersal of crocuta in europe after its spread outside africa (iannucci et al., 2021b). however, pl. perrieri and p. brevirostris were definitely closer in craniodental morphology (and hence inferred ecology) than the giant hyena was to c. crocuta, and their remains are recovered together in some localities (iannucci et al., 2021b). even so, looking at the dimensional differences in dental measurements between the extant species (figure 5), we observed a much larger overlap than that between pl. perrieri and p. brevirostris. therefore, even considering size alone, it seems reasonable to assume that the two species were different enough to occupy different niches, not impeding their coexistence. further support for this consideration comes from the behavioral plasticity of living bone-cracking hyenas. the proportion between hunting and scavenging, diurnal or nocturnal activity, and the location of denning sites, among others, are all factors that can vary and thus facilitate coexistence between living species (kruuk, 1972; mills, 1982, 1990; wiesel, 2006). on the other hand, the “p. brevirostris event” was accompanied by an important reorganization of mammalian faunas and indeed witnessed a peak in carnivoran diversity, particularly of hypercarnivorous and ambush-hunting felids (azzaroli, 1983; palombo et al., 2008; konidaris, 2022). envisioning pl. perrieri mainly as a solitary scavenger, led to the paradox that after its extinction the “place” of a middle-sized scavenger in the carnivoran guild of the late villafranchian remained unoccupied (konidaris, 2022), which might have implications for early hominin dispersal into europe (konidaris & tourloukis, 2021; konidaris, 2022). however, few species are exclusively adapted to a specific feeding behavior and if pl. perrieri had to coexist with p. brevirostris, it likely had to deviate to a more active hunting behavior and/or to target smaller preys. at the same time, this was likely not an easy task, facing the arrivals of several new competitors. it is thus conceivable that pl. perrieri managed to maintain a place in late villafranchian carnivoran guild only for a short geological period, perhaps while other carnivorans were becoming widespread. if the evolution of p. brevirostris was a punctuated event, the likely source area would be eastern asia. indeed, the sample from longdan referred to pachycrocuta by qiu et al. (2004), is intermediate in several measurements between pl. perrieri and p. brevirostris, although somewhat closer to the former species (figure 5). further discovery and description of new (and old) material is needed to understand if a tendency towards larger dimensions occurred in other samples across eurasia, especially focusing on late samples of pl. perrieri. although the trend is not strong, chronologically younger specimens of p. brevirostris are generally larger than earlier representatives of the species, supporting the view of a progressive specialization during the evolution of the giant hyena (iannucci et al., 2021b, 2022), which might have started from the separation of p. brevirostris from pl. perrieri (werdelin & solounias, 1991), or perhaps even in some late samples of the latter species. 5. conclusions although the hyena hemimandible from paciano went lost over the years, critically revising and contextualizing the description and measurements provided by bortolotti (1905) in an updated comparative and taxo nomic framework allowed to reattribute the specimen to pl. perrieri. this species is not documented by extensive samples in italy and testifies to a relatively old age for the fossil locality, thus offering an interesting additional record in the study of early pleistocene european hyenas and underlining the importance and the feasibility of revising historical collections, even when the original remains are lost. in general, there is a relative paucity of descriptions or reconsiderations of historical samples, especially if excluding publications that change previous interpretations, as a likely consequence of the seek for “novelty” that permeates current scientific literature. here, we revised the taxonomic attribution of the paciano hyena, but we emphasize that even confirming an attribution to p. brevirostris, as proposed in the latest work mentioning this sample (argenti, 2004), would have been a significant outcome, and that confirmatory results are worth to share with the scientific community. the giant hyena p. brevirostris likely originated from a large-sized stock of pl. perrieri, but around 2.0–1.8 ma, while p. brevirostris spread into europe, some populations of pl. perrieri remained relatively small-sized and survived for a short time alongside the giant hyena. the impact of competition between extant hyaenid species is generally compensated by their behavioral plasticity, but the evolution of the specialized giant hyena on one side, and the concurrent spread of other late villafranchian carnivorans on the other, might have pushed pl. perrieri towards the limits of its ecological tolerance, eventually triggering its extinction. in any case, there are few localities that document a co-occurrence of pl. perrieri and p. brevirostris, which complicates elucidating the issue. acknowledgments the comparative sample considered here and in previous works has been examined during visiting periods in several institutions, we wish therefore to thank the curators and other personnel that supported us on such occasions, especially manuela aiglstorfer, deborah arbulla, luca bellucci, riccardo castiglia, elisabetta cioppi, andy currant, thomas engel, mihály gasparik, emmanuel gilissen, ralf-dietrich kahlke, linda riti, gerald utschig, and david waterhouse. george e. konidaris and an anonymous reviewer provided valuable comments on a previous version of this article, for which we are grateful. this research received support from the synthesys project http://www.synthesys. info which was financed by european community research infrastructure action under the fp7 “capacities” program (hu-taf-707 and be-taf-708 to rs) and the following synthesys+ project, financed by the european commission via the h2020 research infrastructure programme (de-taf-59 to ai). references agnarsson i., kuntner m. 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(2006) predatory and foraging behaviour of brown hyenas (parahyaena brunnea (thunberg, 1820)) at cape fur seal (arctocephalus pusillus pusillus schreber, 1776) colonies. unpublished phd thesis. university of hamburg, germany. 13 the lost hyena from paciano ms. received: november 30, 2022 revised: december 6, 2022 accepted: december 6, 2022 available online: december 16, 2022 14 amq28(2)111-120 ferrario rivisto 12_2015.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 28 (2), 2015, 111 120 buried landscapes: geoarchaeology of the roman harbor of como (n italy) maria francesca ferrario, fabio brunamonte, arianna caccia, franz livio, elisa martinelli, eleonora mazzola, alessandro m. michetti, silvia terrana dipartimento di scienza e alta tecnologia, università degli studi dell’insubria, como, italy corresponding author: m.f. ferrario <francesca.ferrario@uninsubria.it> abstract: the town of como (n italy) was founded in 59 bc on the shores of the homonymous lake. its present-day environmental setting derives from the interactions between lacustrine, alluvial and human dynamics. the lake coastline moved through time because of alluvial progradation, town expansion and land reclamation. since 1700 ad, more than 200 m of land reclamation towards the north are observed from historical maps of the study area. the harbor is a strategic infrastructure for a coastal town and its localization is a critical issue. archaeological evidence found in the como urban area points to a different position of the harbor during the roman period and the middle ages; presently, those areas are buried below several meters of sediments due to land subsidence and the artificial filling of coastal areas. the results of a geoarchaeological study aimed at understanding the evolution of the coastal area are presented here. adopted methodologies include the collection of available archaeological and stratigraphic data and the analysis of a number of continuous core drillings both on the lake promenade and, for the first time in como, on the lake bottom. sedimentological and geotechnical investigations were performed and archaeological and vegetal findings were studied. a lithological unit consisting of organic silts rich in vegetal remains and archaeological findings has been identified. the thickness of this unit varies from less than 1 meter to 6 meters and it refers to a depositional environment characterized by shallow water and human influence; its deposition started during roman age, when the town was founded and an impressive reorganization of the drainage network took place. geological cross-sections and map reconstructions enable us to define different phases of the town evolution. our results highlight the role of geological research in reconstructing the recent evolution of buried and/or submerged environments: geoscience provides useful information when it is not possible to carry out expensive archaeological excavations at sensitive sites and allows to optimize resource utilization. keywords: geoarchaeology; paleoenvironmental reconstruction; sedimentological analysis; lacustrine harbor; como 1. introduction in areas of ancient civilization, the present-day urban setting can be understood only considering the interaction among natural and cultural factors. geosciences are able to unveil the paleogeography and archaeological evolution at sensitive sites, such as coastal environments. the town of como (n italy) offers the opportunity to apply a geoarchaeological approach at a lacustrine coastal site. sedimentary sequences on the present-day coastal and harbor areas have been analyzed applying a “modern analogue” approach: their sedimentary signature is compared with stratigraphic and archaeological data available for several sites presently buried below the modern town and interpreted as urban harbors (sensu marriner & morhange, 2007) that were in use during different times since the foundation of the town in the roman period. ancient harbors are unique archives of information concerning natural processes, climate forcing, occupation history and human use of a coastal or fluvial area; the study of harbor environments can shed light on the relations between natural dynamics and evolving human societies. a complete investigation has to deal with several scientific disciplines, such as archaeology, history, geology, geomorphology, biology and geochemistry; only through a multifaceted approach it is possible to crosscheck the results obtained by single techniques, that integrate and provide complementary data. the goals of the present research can be summarized as follows: (i) reconstruct the development of the area at the interface between land and the lake by means of a multidisciplinary approach including lithological, sedimentological and geotechnical analyses and geologic cross-sections; (ii) constrain the evolution of the coastline and harbor infrastructures, both in time and space; (iii) differentiate natural and human-induced modifications on the local environmental setting; (iv) acquire independent experimental data derived from the analysis of sedimentary sequences drilled in the coastal area, in order to integrate them with already existing archaeological data. 2. geologic setting and como town stratigraphy the town of como lies at the sw end of the western branch of lake como, located at the foothills of the southern alps and characterized by a lambda-shape. lake como main tributaries are located in the northern sector, whereas the only emissary outflows at the se termination of the lake, then reaching po river. the closed, western branch of the lake is thus a perfect sedimentary trap, which collects sediments from a huge drainage basin, more than 4500 km2 wide (fig. 1a). the historical downtown is built on a nw-se elongated alluvial plain, gently rising from lake level (198 m a.s.l.) to 220 m a.s.l. at its southern margin. two creeks, the cosia and valduce, drain the plain and strongly influenced the evolution of the town, and specifically of the area at the interface with the lake, in the last millennia. nowadays they have been forced to flow underground, beneath the urban area, till their outlet into the lake (fig. 1b). the sedimentary basin hosting the town is composed of more than 180 m of late quaternary loose sediments, settled in lacustrine, palustrine and fluvial environments. the basin is enclosed by two bedrock slopes, composed by mesozoic pelagic carbonates (medolo group – early jurassic) to the ne, and deep sea turbiditic conglomerates (gonfolite group – oligo-miocene) to the sw (fig. 1b; michetti et al., 2013). the gonfolite group and the mesozoic units are in tectonic contact along the gonfolite backthrust, a major regional n-verging structure bordering the como urban area to the sw. fault activity is testified by deformed pliocene-toquaternary sediments (e.g., bernoulli et al., 1989) but also more recent evidence of fault displacement, dating to pleistoceneholocene times, is recorded (livio et al., 2011; michetti et al., 2012). 3. dataset 3.1. como town stratigraphy in the last 40 years, several efforts have been conducted in order to reconstruct the stratigraphic setting of the como urban area. during 1970s, a strong input to this research derived from the studies aimed at comprehend and mitigate the effects of land subsidence, namely the occurrence of severe damage to buildings; it was ascertained that subsidence was due mainly to the overexploitation of groundwater from the deep aquifer (comune di como, 1980). since then, several studies dealt with the hydrogeological and environmental setting, the landscape evolution and with the geohazards of this area (e.g., bini, 1987; comerci et al., 2007; comune di como, 2011 and references therein). the general stratigraphy of the como basin is based on the collection of more than 250 borehole logs, covering a territory of ca. 5 km2 and including the entire urban area (fig. 2). chronological data derives from twelve 14c dating (comerci et al., 2007; ferrario et al., 2015b) covering the time period since ca. 18 cal ka bp. seven lithological units, here described from the top, were defined (comune di como, 1980; comerci et al., 2007; ferrario, 2013); borehole logs were analyzed accounting for the description of grain-size distribution, color, organic and artifact content and, where available, geotechnical index properties. unit boundaries are based on lithological variations or appearance/ disappearance of indicators such as archaeological or organic fragments. our classification corresponds only partially with lithostratigraphic units, because our definition is primarily related to the deposition environment and the palaeogeography of the study area. this choice highlights lateral facies variations, one of the most prominent elements of interest for the present research. unit 1 is composed of heterogeneous reworked material (sands and fine gravels with silty matrix and 112 ferrario f. et al. fig. 1 a) geographical location of como town; lake como and po river drainage basins are also highlighted. b) simplified geologic map of the study area, modified after michetti et al., (2013). topo map: ctr (carta tecnica regionale), provided by regione lombardia, coordinate system: wgs84. fig. 2 map of the como urban area, showing location of boreholes, available 14c dating and archaeological findings. basemap source: http://services.arcgisonline.com/ arcgis/services sparse pebbles) with archaeological and vegetal remains. unit 2 is made up of coarse alluvial sediments related to the post-roman evolution of the cosia delta, after the diversion of the riverbed that was realized for the land reclamation of the como plain, as described below in more detail. unit 3 is constituted by highly compressible plastic silts rich in organic matter and archaeological remains including bricks, pottery, glass fragments and leather tiers. the unit gives a very clear signature on geotechnical probes and is interpreted as the filling of harbor areas (see section 5). unit 4 has a fluvial origin and is made up of holocene coarse sands and fine gravels. unit 5 is represented by laminated clayey silts with sandy horizons; vegetal fragments are dispersed or organized in aggregates or lenses. the unit deposited in a lacustrine\palustrine environment during latest pleistocene and holocene. the two lowermost units, not of interest for the present research, are constituted by late pleistocene inorganic sandy silts with dropstones (unit 6) and medium to coarse sands (unit 7) representative of distal and proximal glaciolacustrine environments, respectively. 3.2. historical evolution and archaeological data the archaeological and historical database for como is of excellent quality. the prehistorical, roman and historical evolution of the city has been the subject of several publications and technical reports (e.g., caniggia, 1968; luraschi, 1987, 2002; uboldi, 1993; jorio, 2004) and is briefly summarized below. the reconstruction is based on more than 100 findings in total, including masonries, pavings, floorings, burials, inscriptions and architectural elements (uboldi, 1993; fig. 2). the oldest human occupation in the area is dated to the iron age, when the mountain slopes surrounding the basin started to be colonized (uboldi, 1993). at that time, the plain was indeed an unhealthy, marshy area, frequently affected by debris flows and flooding events. the hypothesis that the plain was occupied by a roman military camp in the ii century bc is not accepted by all the authors (caniggia, 1968; luraschi, 1987). the foundation of novum comum is well dated and occurred in 59 bc under the roman consul gaius julius caesar. the location of the future town was selected in a strategic position on the lake shore, along the trade itinerary between mediolanum to the south, and central europe (rhine and danube valleys) to the north. the colonizers clearly aimed at taking advantage of lake como as a 60 km long n-s sailing route. the building of the town in the center of the sedimentary plain required an impressive reorganization of the drainage network and related mountain catchment. the cosia and valduce creeks were diverted from the center of the plain and forced to flow at the base of the sw and ne mountain slopes, respectively. northwards the town was naturally protected by the lake, whereas on the other three sides town walls were built. during i-iii century ad, several expansions towards the north are recorded, related to at least three phases of land reclamation (caniggia, 1968). since the beginning of middle ages (iv-v century ad), many more edifices were built close to the lake, but the coastline position was substantially stable till xviii century. historical sources, as well as archaeological findings, refer to different harbors; however, their precise location and the definition of the times in which were active are not well known. at piazza cacciatori delle alpi (fig. 2), during 1999-2000 archaeological excavations, three parallel structures interpreted as roman quays were unearthed (jorio, 2004); at piazza mazzini a monumental marble block resting upon wooden remains, interpreted as the rests of a boat, was found (uboldi, 1993). 4. methods the coastal area was studied through different drilling investigations aimed at characterizing the site for an engineering project for mitigating the flood hazard: 1997 drillings: 10 cores were drilled, each one 60 m deep; in situ tests were performed and 9 piezometer and a magnet extensometer were installed inside the drilling holes. laboratory tests were performed on 88 undisturbed and 9 remolded samples and 5 cptu tests were carried out. 2010 drillings: the survey was performed for hydrogeological purposes mainly; 11 piezometers were installed in drillings up to 25 m deep and a number of permeability tests were done. 2013 drillings: 5 continuous core drillings and 2 more cores for cross-hole seismic tests were realized; for the first time, some drillings were made on the lake bottom. subsoil properties in static and dynamic conditions were defined and in situ and laboratory tests were performed. 113 buried landscapes: the roman harbor of como (n italy) fig. 3 location of available stratigraphic data in the present coastal area and trace of the geologic sections (fig. 8). results gained from these investigations have been analyzed mainly from an engineering perspective (ferrario et al., 2013, 2015a, b). here we present the results of a geoarchaeological study conducted on new sedimentary sequences, collected in 2014 on the western portion of the lake shore. cores were drilled by a machine-operated drill rig, core diameter is 86 mm. a total of 6 cores, 30-to -40 m deep, were drilled on the promenade as well as on the lake bottom. five more cores, 10 m deep, were equipped with piezometers. ancient city maps and historical chronicles have been studied for precisely reconstructing changes in the coastline since xvii century ad (caniggia, 1968; gianoncelli, 1975): maps were georeferenced and line drawing of the main features was realized in arcgis environment. chronological constraints since latest pleistocene are provided by a number of 14c dating (comerci et al., 2007; ferrario et al., 2015b; tab. 1) obtained at several sites in the como basin and integrated with information deriving from the archaeological record (uboldi, 1993; jorio, 2004). calibration was carried out applying oxcal software (https://c14.arch.ox.ac.uk/oxcal/oxcal.html, last accessed january 2015) and the intcal13calibration curve (reimer et al., 2013). 4.1. drillings: in situ tests the elevation of each core was calculated based on the municipal 1:2,000 scale topo map acquired in 1994; the elevation of cores on the lake bottom was calculated by subtracting water depth at each point. digital photographs were taken of every sediment core and, as soon as the sediments were collected, pocket penetrometer and shear values were measured. a detailed lithostratigraphic description was based upon grain size estimation, texture, color (with munsell soil color chart), presence of organic substance and artifacts. peculiar archaeological findings and some organic sample suitable for 14c dating were collected. 4.2. drillings: laboratory tests two sediments were sampled for analysis under laboratory conditions: the main physical parameters and a preliminary estimate of the biological content were investigated. sampling was not based on a regular spatial interval, but more emphasis was put on the most interesting parts of the sequence, namely where lithological markers or peculiar sedimentary features are present. four different kinds of samples were taken: (i) ca. 100 g of wet sediments were collected in small plastic containers for texture analysis, exoscopic indicators (degree of roundness and angularity) and organic abundance estimation; at this stage of the research, 20 to 35 samples were taken for each of the 30-to-40 m deep drillings. (ii) a total of 21 samples for grain size analysis with sieving and sedimentation procedure were stored in plastic bags. (iii) natural density and unit weight were calculated on 109 samples collected through steel or plastic cylinders of known volume. (iv) undisturbed samples were taken with osterberg samplers for geotechnical probes. water content, grain size and unit weight have been determined on all the cores, indeed two specific cores (si7 and si12) were selected for determination of organic abundance. grain size determination was performed through sieving and sedimentation procedure, according to astm d422 procedure and results were statistically analyzed. bulk density was calculated dividing dry weight by the sampler known volume. sediment samples of the above-mentioned category (i) were analyzed with the following procedure: they were weighted immediately after the sampling and then oven dried at 105°c in order to calculate water content. they underwent mechanical sieving for sorting out coarse fraction (> 2 mm), very coarse sand (2 mm – 850 µm), medium to coarse sand (850 – 250 µm), fine sand (250 – 150 µm), very fine sand (150 – 63 µm) and silts/ clays fraction (< 63 µm). these categories were defined considering the predominance of fine sediments and the almost negligible amount of material larger than 250 µm. on the finest fraction color was determined using the munsell chart, whereas the sand fraction was examined under a stereoscopic microscope (carl zeiss kl 200, magnification 8 – 50 x). organic abundance, roundness and angularity were estimated by comparison with reference charts representing four classes (for organic abundance: 1, absent; 2, rare; 3, present; 4, abundant). 5. results and discussion obtained data allowed to document with unprecedented detail the holocene evolution of the area, the first human influence before the foundation of como and finally the dramatic hydraulic and geomorphic changes induced during roman and historical times. sedimentological proxies are discussed in the following according to their relation in respect of the local harbor evolution. 5.1. pre-harbor environment: natural processes and first anthropic influence during the last glacial maximum (lgm), the area nowadays hosting the town of como was fully covered by ice. the sedimentary sequence in the como basin was generated by the retreat of the glacier front towards the north: a proglacial lake formed at an elevation of 270 m a.s.l. and inorganic glaciolacustrine proximal (unit 7) and distal (unit 6) deposits settled. with the inception of a milder climate, the deposition of palustrine organic silts (unit 5) begun; this moment is dated at 18.5 – 17 ka bp (via valleggio and piazza verdi sites; comerci et al., 2007; ferrario et al., 2015b) and the lake stood at ca. tab. 1 14c-ams ages and calibration of wood fragments from core si3 on the lake shore area of como. 114 ferrario f. et al. 215 m a.s.l. vegetation history has been reconstructed by means of palaeobotanical analyses on the piazza verdi cores (martinelli, 2014). a succession starting from few pioneer herbaceous species, through arboreal species (lateglacial), continental forests (bölling/allerød interstadial) and mixed mesophilous forests (holocene) developed. the first human influence is attested on the basis of the local fire history since 8.2 ka bp and progressively intensified, because of deforestation, agriculture and livestock farming. unit 5 has been dated at several sites, namely s. abbondio (castelletti & orombelli, 1986; comerci et al., 2007), via valleggio (comerci et al., 2007) and piazza verdi (ferrario et al., 2015b). unit 5 was cored both in si12 (5.72 – 30.00 m depth) and si7 (17.37 – 40.00 m) drillings. it is constituted by sandy clays rich in organic matter and vivianite, an iron orthophosphate that is formed under reducing redox environments and alkaline conditions. the unit settled in a lacustrine-palustrine environment. vegetal fragments are dispersed or organized in aggregates or lenses. usually an alternation of mm-thick organic strata and mm-to-cm inorganic strata is present. locally, layers are convolute or inclined up to 40° and flame-structures (fig. 4b) are present, pointing to possible reworking of sediments. we interpreted these features as related to gas emission, but other triggering mechanisms cannot be ruled out, including sediment overload, earthquake shaking, storm, lake-level variations and biological activ 115 fig. 4 sedimentary structures and archaeological findings recovered from the drillings: a) unit 3 intercalated between anthropic reworked material of unit 1 (si1, depth: 6.70-7.20 m below ground surface, 2013 drillings); b) laminated structure and gas-emission features in unit 5 (si3, depth: 35.00-40.00 m, 2013 drillings). the holes in the core represents pocket penetrometer and vane borer measurements; c) pottery fragments, age uncertain (pz11, depth 7.20 m, 2014 drillings); d) glass fragment, early middle ages (si3, depth 8.00 m, 2013 drillings); e) and f) leather tiers, imperial age? (si3, depth 13.12-13.18 m, 2013 drillings). borehole location is shown in fig. 3. 115 buried landscapes: the roman harbor of como (n italy) ity. the elevation of the base of the unit was ascertained with the 1997 drillings and runs at 50-60 m depth in the western sector of the lake shore, while it increases to 20 m depth in the eastern sector. sedimentological analyses performed on 50 samples taken from cores si12 (fig. 5) and si7 (fig. 6) allowed to accurately characterize the index properties of unit 5. water content is highly variable in si12 (3590%), whereas in si7 is more clustered (35-60%); unit weight increases with depth, from ca. 10 to 16 kn/m3. the coarse fraction (> 2 mm) is very low, in the order of 1% and composed both by mineral or biological fragments; sand varies between 20 and 70%, with an average of 49% in si12 and 46% in si7. the finest fraction (< 63 µm) corresponds to 30 – 85% of the sediment texture (average 49 and 53% for si12 and si7, respectively). concerning the sand fraction, it is composed almost only by very fine sand (150 – 63 µm). the sedimentation of unit 5 went on for several millennia; the unit is generally overlaid by alluvial deposits. a wood fragment collected from si3 at 38.40 m depth (see fig. 3 for location) yielded an age of 7.5 ka bp (ferrario et al., 2015b; table 1). the boundary between unit 5 and 4 is a diachronic erosive surface, being younger moving towards the north. this limit has been dated at 5.8 and 4.5 ka bp at via valleggio and piazza verdi sites, respectively (comerci et al., 2007) and corresponds to the progradation of the cosia alluvial fan on the palustrine basin. considering the age difference and the distance between the two sites, an average velocity of progradation of almost 1 m per year can be estimated. the fast progradation abruptly ceased ca. 2 ka bp when the foundation of novum comum occurred. unit 4 thickness ranges from 10 to 25 meters, depending on the distance from the river course. the thickness rapidly decreases from south towards the lake, where the unit is absent. unit 4 was not cored during the 2014 drillings because it pinches out few meters southward. 5.2. harbor environment the boundary between unit 5 (or unit 4, where present) and the overlying unit 3 is an unconformity marked by: (i) the appearance of sandy clays of low consistence and extremely rich in water; ii) a change in color, from grey to dark brown; iii) the presence of archaeological findings (bricks, potsherds, glass); iv) a sharp signature on the geotechnical parameters, namely a decrease in cone resistance and an increase in the friction ratio recorded by cptus (ferrario et al., 2013). driven by these observations, we interpreted this limit as the harbor foundation surface (hfs, sensu marriner & morhange, 2007), marking the beginning of human modification of the basin. sediments of unit 3 are definitely homogeneous in lithology and belong to the oh-mh category in the casagrande plasticity chart; water content is extremely fig. 5 sedimentology and organic abundance of core si12. lithological description is based on in situ analysis of the core (cl: clay; si: silt; sa: sand; gr: gravel), whereas grain size, water content and unit weight derive from laboratory measurements. the abundance of organic material (org. abund., 1: absent; 2: rare; 3: present; 4: abundant) is estimated by means of a stereoscopic microscope. 116 ferrario f. et al. high (ca. 90%) and unit weight quite low (ferrario et al., 2015b). archaeological evidence based on chronology of masonries and materials (jorio, 2004) suggests that unit 3 begun to settle during the roman age, when the town was founded. before that period, the strong sedimentary supply of the streams resulted in an higher energy of the local environment. man-made interventions on the river courses promoted alluvial deposition on the western side of the plain, whereas in the central sector a low-energy environment with shallow waters developed enabling the deposition of unit 3. here, anoxic conditions are present and sediments are saturated with water, thus otherwise perishable biological and archaeological materials (leather, wood, peat, seeds) can be preserved. plastic silts and clays contain a coarser fraction made up by biological remains and artifacts (fig. 4). during roman age, the harbor environment was first located close to the present-day piazza mazzini (see fig. 2 for location), then moved towards the northeast (fig. 7) due to silting of the basin. harbor clays settled atop older sediments constituted by unit 4 or unit 5; a sequence of alternating strata of unit 4 and 3 is locally recorded in the western sector of the urban area, attesting for both lacustrine and alluvial floods. on the lake shore, the age of the unit has been bracketed between viii and xv century ad (si3; ferrario et al., 2013). a particular situation was encountered in si1, located on the eastern part of the lake shore (see fig. 3): here, a 70-cm thick layer belonging to unit 3 is intercalated within anthropic materials of unit 1 (fig. 4a). the lower part of unit 1 has been interpreted as a manmade filling built in order to protect a coastal infrastructure; unit 3 refers to a quiet environment developed for a short time and then covered by another phase of manmade filling accumulation, presumably related to the land reclamations occurred since xviii century. 5.3. post-harbor environment and the most recent evolution the upper limit of unit 3 can be defined as the harbor abandonment surface (has, sensu marriner & morhange, 2007). the abrupt boundary between fine silts of unit 3 and overlying coarser materials represents coastline progradation of both natural or man-made origin, which caused a silting of the harbor basin and its loss of functionality. in the southern and western sectors of the town, unit 3 is overlaid by the coarse sediments of unit 2: during historical times, alluvial floods promoted coastline progradation, culminated in the landlocking of the harbor basin. however, in the central and northern parts of the town, unit 1 lies in unconformity over unit 3, attesting to anthropic modification of the coastline. fig. 6 sedimentology and organic abundance of core si7. lithological description is based on in situ analysis of the core (cl: clay; si: silt; sa: sand; gr: gravel; symbol legend is shown in fig. 5), whereas grain size, water content and unit weight derive from laboratory measurements. the abundance of organic material (org. abund., 1: absent; 2: rare; 3: present; 4: abundant) is estimated by means of a stereoscopic microscope. 117 buried landscapes: the roman harbor of como (n italy) man-made fillings are constituted by medium-tocoarse sands and fine gravels with silty matrix; accumulation of blocks, mainly made of limestone, is recorded on the coastal area. on the lake shore area, unit 1 is typically younger than 200 years and reaches a maximum thickness of ca. 15 meters. the coastline evolution in the last centuries is constrained by old city maps (gianoncelli, 1975): at least three phases of land reclamation were realized in xviii-xix century. present-day piazza cavour was the dock of the town till 1870, when a notable reorganization of the coastline took place and the last marshy areas were reclaimed. coastal changes show a progressive regularization, obtained through the filling of natural coves. 5.4. geologic cross-sections stratigraphic data were arranged in two different cross-sections, illustrated in fig. 8. vertical and lateral facies changes are common and reflect the paleogeographic evolution of the area driven by natural as well as human-induced factors. unit thickness varies notably in limited planar extents, especially along the ns direction. instead, on the w-e direction, lithological units can be depicted along their extension along the lake shore. fig. 8b shows the main stratigraphic characteristics of unit 3: in the western part it overlies unit 4, whereas to the east it overlies unit 5. locally, a more complex setting is present, such as in correspondence with core si1: the interpretation drawn here suggests a lateral facies contact between unit 4 and unit 1, both passing to the top to unit 3 and finally to unit 1. in core si1 anthropic fills are present down to 13 m depth; the lower part is interpreted as a protective filling for coastal infrastructures, including a staircase. it was then submerged for a short period, testified by a 70-cm thick layer belonging to unit 3 at 6.70 – 7.30 m depth and then covered by another phase of man-made deposits (fig. 4a). 6. conclusions this paper illustrates geoarchaeological research that we performed on the como coastal area, essentially fig. 7 map of the como urban area, showing the holocene position of the cosia alluvial fan and the evolution in coastline and harbor position. modified after ferrario et al., 2013. 118 ferrario f. et al. based on the detailed analysis of sedimentary sequences sampled through extensive coring. our preliminary results allow to draw some conclusion, as summarized below: the comprehensive characterization of the area at the interface between land and the lake clearly shows the strong relationship existing between harbor evolution, natural events and human occupation; sedimentological analyses corroborate available stratigraphic and archaeological data and allow to draw geological cross-sections, aimed at reconstructing the local landscape evolution in the last millennia; the adopted methods, based on the integration of stratigraphic, sedimentological, geotechnical and archaeological proxies, document that a crossdisciplinary approach is the best strategy of investigation when natural and anthropic processes are superimposed within each other, as typically occur in the coastal settings of regions with ancient civilization; the model of the landscape evolution, if properly integrated in urban planning, is suitable for reaching a better management of the cultural heritage and for revealing possible risk for the local infrastructures and assets; geological techniques are an interesting option when it is not possible to perform archaeological excavations, due to technical difficulties (submerged environments, groundwater) or economic costs; the possibility offered by geoscience to use non-destructive methods is a valuable tool for the protection of very sensitive environments and heritages; obtained results provide guidance for future research involving the integration of the conspicuous geological and archaeological data available for the study area; the como case is one of the first lacustrine settings studied on a geoarchaeological basis. the main conclusions arising from the study therefore include not only the specific results achieved so far, but also interesting methodological opportunities for future research at como or in other similar lacustrine coastal sites. acknowledgements the authors would like to thank the como municipality; georicerche s.r.l. is acknowledged for the field investigations and for supporting 14c dating. topographic maps were provided by regione lombardia. giuseppe orombelli and paolo mozzi contributed to the improvement of the manuscript. references bernuolli d., bertotti g., zingg a. 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(1993) carta archeologica della lombardia. como. la città murata e la convalle. franco cosimo panini, modena. ms. received: may 20, 2015 final text received: june 18, 2015 120 ferrario f. et al. amq 27 sn 2 mazza pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 27 (1), 2014, xi xvii paleontology spring field school report on the excavation of castel cellesi (bagnoregio, viterbo, central italy) paul mazza department of earth sciences, university of florence, florence, italy corresponding author: p. mazza <paul.mazza@unifi.it> abstract: fossil remains of palaeoloxodon antiquus were found in 2013 at "campo della spina", near the small village of castel cellesi (bagnoregio, viterbo, central italy). a paleontology spring field school was planned, under the patronage of aiqua and the italian paleontological society, to raise funds for the excavation. sixteen students attended the lectures delivered by eight eminent teachers, most of which members of aiqua. the excavation unearthed many bones of the highly disarticulated skeleton of palaeoloxodon. following an agreement reached with the regional board of the ministry of cultural heritage and environmental conservation of southern etruria the specimens were left in situ. they will be housed in an eco-structure that will be built over them and that will represent a cutting-edge museum with no such equivalent in italy. keywords: palaeoloxodon antiquus, paleontological excavation, spring field school, middle pleistocene, central italy. preamble in july 2013, the discovery of fossil remains of a large-size, senile palaeoloxodon antiquus at "campo della spina", a few kilometers southwest of the hamlet of castel cellesi (bagnoregio, viterbo, central italy, fig. 1), was reported to the department of earth sciences of the university of florence (fig. 2). an exploratory excavation was conducted at the end of august. on that occasion, a grid layout of 1 m2 georeferenced squares, oriented nw-se, was established over the area to be excavated. the squares were identified with letters and numbers, starting from a1, at nw, to d7 at se. three squares were explored, namely, a4, b5 and c6, where bones were exposed. a growing concentration of bones a left humerus and numerous ribs was found from a4 to c6 (fig. 3). part of the specimens were immersed, whereas others lied over, a greyish silty sedimentary body containing small volcanic breccias. a systematic excavation was therefore planned late in spring 2014. to raise the funds for the excavation a paleontology spring field school was also planned at castel cellesi. sixteen students and eight teachers from many italian colleges participated in the field school (fig. 4). by the first half of june, geoelectrical and georadar investigations were conducted to explore the resistivity of the fossil-bearing deposits, as well as to locate possible concentrations of bones. these surveys intended to reduce the excavation activities to a minimum, and save time and money. the geoelectrical exploration showed a lens of less resistive sediments dipping northwards. in contrast, the georadar survey gave chaotic and unreliable results. the excavation (figure 5) excavations began on the 16th of june, 2014. the operations started from the squares b6, a5, c7 and d6 that were adjacent a4, b5 and c6 that had been explored in spring. this was decided following the bones that lied exposed from the walls of the three previously dug squares. the excavation was conducted using a methodology of "exfoliation" of the layers. stratigraphy (figure 6) within the excavated area, under the topmost 5-8 cm of trampled sediment, lie 50-60 cms of massive, ochercoloured silty-clay (us2), consisting of reworked tuffaceous material with lithoclasts of different composition, but mostly of pumice, and with plant remains of various size, rhizoliths, small, white, thin-shelled gastropods. bioturbations are also visible. this layer lies over a similar one (us3), some 90 cm thick, separated by a very hard lateritic duricrust, which forms an irregular horizon fig. 1 location map of the castel cellesi excavation. sandwiched in between the two layers. the duricrust coats 16 to 90 cm-wide channels. us3 contains a large sedimentary lens, 30 to 50 cms thick, made of a gravel of poorly-rounded and poorly-sorted lithic elements floating in a greyish silty matrix (us4). the upper surface of the lens is irregular. it often intrudes upwards in us3 forming diapir-like pillars or flame-like structures. the lens is the fossil-bearing sedimentary body of the succession. the bones lie within and upon the grey gravelly-silty lens. all the layers are directed n-s and dip mazza p. xii fig. 2 lower molars of palaeoloxodon antiquus. the specimens were the first evidence of the presence of the fossiliferous site. xiii paleontology spring field school, castel cellesi excavation fig. 3 result of the exploratory excavation at the site. fig. 4 some of the participants of the castel cellesi’s paleontology spring field school during the excavations. 10° n. the fossil-bearing lens dips markedly towards square d3. more in general, the stratigraphic succession, consists of the following units, from the bottom upwards: 1) about 20 cm of rhythmic grey clay laminae, each approximately 1 cm thick, interbedded with fine-grained sands made of quartz and volcanic minerals (us7: the base of this unit is not exposed: fig. 6 a, b); 2) 5 cm of light-yellow to whitish clayey marl with intercalations of lenticular grey clay and fine-grained sand made of quartz and volcanic minerals. this level contains plant remains rhizoliths and ripple-marks (us6: fig. 6 a, b); 3) 30 cm of fine-grained sand and laminated clay, at times lenticular, with frequent plant remains (us 5: fig. 6 a, b); 4) about 60 cm of light-grey, massive clayey silt, containing reworked tuffaceous material, various kinds of lithoclasts, numerous plant remains of different size, rhizoliths, small, thin-shelled, whitish gastropods and bioturbations (us3: fig. 6 c-f); 5) lateritic duricrust (fig. 6 c, d); 6) about 150 cm of solid, ocher-colored clayey silt, similar to the underlying ones of us3 (us2: fig. 6 c -d, f, g-h). in the upper part, at the transition to the overlying us1, the unit is markedly reddened by soil processes (fig. 6 f-h); 7) about 60 cm of whitish lacustrine diatomitic deposits. this level contains numerous plant remains, rhizoliths and shells of small freshwater mollusks. at the base there are several channels, some 100-120 cm wide (us1: fig. 6 f-h). the succession likely belongs in the tuffs of the "paleo-vulsini" complex. it is therefore tentatively dated to around 600 ka. nonetheless, this age attribution is still provisional and needs to be verified. the specimens given the limited time granted for the excavation and after an agreement reached with the regional board of the ministry of cultural heritage and environmental conservation of southern etruria to leave the specimens in situ and not to recover them, the excavations were extended to the following squares: a3, b3, b4, b6, b7, c3, c4, c5, c7, d3, d4, d5, d6 and d7. the bones sum up to a total of 130. they belong almost entirely to paleoloxodon antiquus, except a small fragmental rib likely of a cervid (cervus elaphus?), found at the boundary between squares c5 and c6. the skeletal elements are all disarticulated, with the only exception of three thorachic vertebrae. the bones were nonetheless found accumulated in a relatively small area. many bones seem having a bimodal orientation nw-se and ne-sw, but this needs careful taphonomic verification (fig. 5). hypothetical reconstruction of the site's formation the fossiliferous lens (us4), consisting of poorly rounded and poorly sorted gravel elements floating within a silty matrix has the characteristics of a fairly fluid debris-flow. these highly concentrated slurries of sediment and water are triggered by high relief, abundant xiv fig. 5 plan view of the excavation. mazza p. xv paleontology spring field school, castel cellesi excavation fig. 6 a-b. basal part of the castel cellesi stratigraphic succession. c-e. details of the stratigraphic units met at the excavation. loose sediment trapped in steep catchments and a sharp peak in surface hydrological activity, during prolonged rain. the flame-like structures that deform the upper surface of the fossil-bearing sedimentary body, as well as the roughly bimodal arrangement of the bones, indicate that the debris-flow was probably quite fluid. based on the degree of wear of its teeth and on its particularly large size, the castel cellesi elephant was an old male. the characters of the stratigraphic succession indicate sedimentation in a shallow water basin, likely a swamp or a small lake. the sedimentary succession suggests that the water body alternatively deepened evolving into a lake or shallowed drying up and being replaced by a network of channels interspersed with vegetated plains. the elephant probably died along the banks of the water body, where us7-5 had already deposited, possibly bogged in the muddy sediments. nonetheless, this cannot be verified until the animal’s extremities are found. alternatively, the elephant might have died from dehydration during a drought event. the degree of disarticulation of the skeleton, as well as the lack of evidence of weathering and carnivore ravaging on the bone surfaces indicate that the carcass probably decayed submerged in the water body. once decomposition had reached an advanced phase, the debris flow (us4) ran into, entrained and buried, the already disar xvi mazza p. fig. 7 draft of the project for the structure that shall house the castel cellesi paleontological site. ticulated elephant carcass, scattering the bones. the water body still maintained for a while and its normal pattern of sedimentation was restored (us3). then it dried up, at least locally, and the area was subjected to soil formation and carved by a set of small channels. alternating wet and dry conditions favored the formation of the lateritic duricrust. the area subsequently drowned again and the swamp/lacustrine sedimentation was again resumed (us2). after that it emerged once more, new soil was formed and then it definitively drowned evolving in a lake. during this final phase the area was enriched with silica of volcanic origin, which favored the blooming of diatom colonies (us1). future prospects the fate of the castel cellesi elephant is unique in italy. contrary to usual practice, the fossil skeleton will not be retrieved from its natural grave. the regional board of the ministry of cultural heritage and environmental conservation of southern etruria made the decision to leave it where nature preserved it. the skeleton, together with the stratigraphic succession next to it, will be housed in an eco-structure, built in glass and wood, which will also include a mounted copy of a skeleton of palaeoloxodon antiquus, a classroom for lessons in situ and a laboratory (fig. 7). the building will be powered by photovoltaic panels and will use rainwater, which will be recicled using plant water purifiers. if the project will be realized in full respect the plan, the structure has no such equivalent in italy. being located in almost incontaminated surroundings, it would be a natural science laboratory for students from the schools of every order and degree, as well as for researchers of the widest range of natural history fields. it can even be used by archeologists, because the site is very close to etruscan and roman finds. the project is indeed ambitious. but ambitions are made to achieve. acknowledgements i wish to thank deeply aiqua and its president prof. adele bertini for the patronage of castel cellesi’s paleontology spring field school. i extend my gratitude to profs. maria rita palombo, anna gandin, mauro coltorti, giorgio manzi, and pierluigi pieruccini and to phd dr. andrea savorelli who contributed to the success of the school. i am particularly indebted to the 16 students who participated in this enterprise: without their help and financial support the excavation and the castel cellesi’s paleontology spring field school would have been a mere daydream. i am also most grateful to the italian paleontological society (spi) for the patronage and helpful support. many thanks also to dr. maria letizia arancio, of the regional board of the ministry of cultural heritage and environmental conservation of southern etruria, for her most helpful assistance and advice. xvii paleontology spring field school, castel cellesi excavation ms. received: october 30, 2014 final text received: november 14, 2014 impaginato bosi ll’’iinntteerrpprreettaazziioonnee ddeellllee ssuuppeerrffiiccii rreelliittttee nneellll’’aappppeennnniinnoo cceennttrraallee:: iill ccaassoo ddeellllaa zzoonnaa ddii ccoollffiioorriittoo ((pprroovv.. ppeerruuggiiaa ee mmaacceerraattaa)) cc.. bboossii c. n. r. istituto di ricerca sulla tettonica recente via del fosso del cavaliere 00133, roma e-mail: bosi@irtr.rm.cnr.it riassunto l’utilizzazione delle successioni di superfici relitte per la ricostruzione dell’evoluzione geologica in aree di catena dispone di presupposti metodologici ancora piuttosto approssimativi, come può ritenersi indirettamente dimostrato dai risultati contrastanti recentemente ottenuti da due gruppi di ricercatori nella zona colpita dal terremoto di colfiorito (settembre-ottobre 1997) nell’alto bacino del chienti (parte centrale dello spartiacque appenninico umbro-marchigiano). questo contrasto è in larga misura connesso ai modelli genetici assunti, nonché ai criteri seguiti nella delimitazione e correlazione dei lembi di superfici relitte. un esame critico della bibliografia geologica ha portato a focalizzare l’attenzione sulle spianate sommitali (di regola interpretate come lembi di una stessa “paleosuperficie sommitale”) e sulle successioni terrazzate di superfici relitte in esse incassate. in relazione al primo argomento, partendo dalla critica alla correlazione delle spianate sommitali in quanto sommitali e dalle riserve sulle ricostruzioni che se ne possono trarre (in particolare su quella che estenderebbe a tutta la penisola la suddetta paloesuperficie), è stata prospettata la possibilità che le spianate sommitali, pur facendo parte del paesaggio relitto esistente all’inizio dell’approfondimento del reticolo idrografico conseguente al sollevamento tettonico, possano essere riferite non ad un unico evento morfogenetico, ma a più eventi verificatisi nell’ambito di tutta l’evoluzione geologica precedente. in relazione al secondo argomento, è stata prospettata l’ipotesi che i lembi, abitualmente modesti, delle superfici che costituiscono le successioni terrazzate non corrispondano alle tracce residue di larghe spianate vallive, ma a ciò che resta di spianamenti verificatisi in corrispondenza di insiemi di più modeste incisioni connesse con livelli di base relativamente uniformi. sulla base di una riconsiderazione metodologica che tiene conto delle ipotesi proposte e dei risultati già pubblicati dai due gruppi di autori sopra citati, è stato eseguito lo studio di una vasta zona comprendente l’area epicentrale del terremoto di colfiorito. questo studio ha portato alla definizione di una successione di superfici relitte, la cui distribuzione plano-altimetrica ha permesso di delineare una successione di 7 distinti ordini di spianate, incassate entro un insieme di spianate sommitali fra loro non correlabili. dalla distribuzione plano-altimetrica dei lembi osservati sono state ricavate precisazioni tettoniche che riguardano: l’inizio del sollevamento che risulterebbe riferibile ad un pliocene inoltrato, e quindi probabilmente più recente di quanto in precedenza ipotizzato; la collocazione cronologica dell’inizio dell’attività delle principali faglie che sembrano rappresentare l’espressione superficiale della struttura sismogenetica responsabile del terremoto. abstract the study of the remnant landsurfaces is of considerable interest with regard to the reconstruction of the geological evolution of the chain area. the methodology available for the use of these surfaces is still rather approximative, as is shown by the contrasting results recently obtained by two groups of researches in the area hit by the colflorito earthquake (september -october 1997, mw 5.6-6.0) in the high valley of chienti, corresponding to the central part of the divide of the chain in the umbria-marche region. this contrast mainly regards the number of landsurfaces and the area distributions of the remnants; it is in the main part connected to the genetic models assumed and to the criteria followed in the delimitation and correlation of the remnants. a critical examination of the geological bibliography regarding the planation surfaces of most of the central and southern apennines, has brought our attention to the summit surfaces and to the terraced flights of the remnant surfaces. in relation to the first argument it has been highlighted that it is not very frequent that the adjacent remnants are so near to prove directliy to belong to the same planation surface. in most cases this belonging is affirmed on the basis of correlations founded on the summit positions of the remnants and on the altitude which is often relatively even. this correlation must be evaluated with great caution in that, not only is it without adequate support, but it lends itself to hard to believe deductions. this has been recently proposed on the extension of the same summit surface to all the apennines. an alternative hypothesis can be proposed, founded on an evolutionary model, according to which the strips of the summit surfaces can be referred to not just one morphogenetic event, but to a group of further events, occurred in all the previous geological evolution. in relation to the terraces flights is formulated the hypothesis that the usually modest strips, that constitute them, do not correspond to the remaining traces of large valley bottoms but of that which remains of planation surfaces in correspondence to a group of more modest incisions attributed to the same level of deepening network. both evolution schemes proposed have noticeable implications with regards to the tectonic interpretation of remnant surfaces. the first leads us to believe that the operation of obtaining information on the extent and the amount of the tectonic uplift from surfaces altitude, must be limited to only the areas where concrete correlations can be proposed. the second, considerably reduces the importance of the present altitude of the surfaces in terraced successions. on the basis of these evolutionary schemes and of a re-examination of the criteria for delimitation and correlation of the observable strips, a study of the area epicentral to the colflorito earthquake, including the plateau of the same name was carried out. this study has led to the definition of a succession of seven distinct planation surfaces carved into a group of summit surfaces, referred to pliocene. with regards to this group, the only possible correlations are those among the remnants maintained in the m.fema m.cavallo sector. some of the most important sufaces to be mentioned are: the m.tito surface widely developed in the colfiorito plateu and in correspondence to the present chienti valley, referable to pliocene or to the initial pleistocene. the rasenna surface present only in the colfiorito and m.lago plateau, that cut sediments having an age of about 420.000 years from the distribution of the strips observed, other tectonic data has been collected that regard: the start of the uplift that would result referable to an advanced pliocene, and thus probably more recent than that which had been previously hypothesised. the chronological collocation of the start of the activity of the main faults that seem to represent the superfcial expression of the sismogenetic structure responsible for the earthquake. parole chiave: superfici relitte, tettonica, appennino centrale key-words: remnant surfaces, tectonics, central appennines il quaternario italian journal of quaternary sciences 1155(1), 2002, 69-82 11.. pprreemmeessssaa le maggiori difficoltà che si incontrano nella ricostruzione dell’evoluzione geologica quaternaria della catena appenninica derivano notoriamente dalla scarsità di successioni stratigrafiche in grado di fornire significativi orizzonti di riferimento per valutazioni tettoniche. i sedimenti plio-quaternari, prevalentemente rappresentati da depositi fluviali terrazzati entro incisioni vallive e da coltri di depositi detritici e colluviali sui versanti, sono infatti molto discontinui e di regola privi di elementi di datazione. le successioni lacustri sono di maggior utilità, ma hanno l’inconveniente di interessare solo una porzione molto piccola della catena. si rende quindi opportuno considerare anche altri elementi geologici, fra i quali hanno un ruolo importante i lembi di spianate riconducibili a superfici relitte, largamente diffusi lungo tutta la catena appenninica (bosi, 1978). in modo molto schematico si può ritenere che queste superfici possano essere utilizzate in due modi diversi. il primo consiste nell’utilizzare le successioni di superfici relitte per ricavarne indicazioni sulla mobilità tettonica delle aree nelle quali queste successioni sono rappresentate. un’approccio di questo tipo è, ad esempio, quello delineato da bosi et al. (1996) mirante a definire zone a diversa mobilità tettonica verticale di zone circostanti il fucino, e più ampiamente sviluppato da amato e cinque (1999) per la caratterizzazione cinematica quaternaria dell’appennino campano-lucano. il secondo modo consiste nel trattare le singole superfici relitte alla stregua di orizzonti di riferimento di tipo stratigrafico (quali strati, discontinuità, limiti di unità, ecc.) per il riconoscimento di specifiche deformazioni tettoniche. lo studio al quale si riferisce la presente nota riguarda prevalentemente le problematiche coinvolte in questo secondo procedimento, prendendo lo spunto dall’esame delle superfici relitte esistenti nell’area maggiormente colpita dal terremoto di colfiorito del settembre-ottobre 1997. la zona esaminata, comprendente le aree epicentrali delle tre scosse principali (cesi mw=5.7; annifo mw=6.0 e sellano mw=5.6, amato et al., 1998), corrisponde alla parte dello spartiacque appenninico delimitato all’incirca dal potenza a nord e dal nera a sud (fig.1). questa zona può essere suddivisa in due settori orograficamente diversi. il settore orientale è costituito da un gruppo di accentuati rilievi, culminanti a nord con il monte pennino (quota 1571) ed a sud con il monte fema (quota 1575), profondamente inciso dalle valli del chienti e del nera. all’estremità nord-orientale di questo settore è chiaramente individuabile un piccolo altopiano caratterizzato da estese depressioni carsiche (piano di monte lago). il settore occidentale corrisponde sostanzialmente ad un altopiano variamente dissecato, caratterizzato da modesti rilievi (quote massime 1000-1100 m) che emergono da un insieme di grandi depressioni carsiche (piano di colfiorito, piano di annifo, ecc.). questo settore risulta sospeso verso w sul bacino del topino e verso s dal bacino del nera da un insieme di ripidi versanti. nei paragrafi che seguono, la descrizione dei risultati ottenuti per quest’area è preceduta dall’inquadramento dei problemi posti dallo studio delle superfici relitte appenniniche, con particolare riguardo a quelle dell’appennino centrale. 22.. ssttuuddii pprreecceeddeennttii superfici d’erosione relitte sono state sommariamente descritte in appennino fino dai primi decenni del ‘900 (marinelli, 1922; sestini, 1939; lipparini, 1935). descrizioni più dettagliate sono quelle degli anni ‘60-‘70 riportate nei lavori di demangeot (1965) e di bertini e bosi (1976; 1978) per l’abruzzo, di desplanques (1969) per le marche, di marchetti (1974), bernini et al. (1977) e marchetti et al. (1979) per l’appennino emiliano, di bartolini (1980) per l’appennino lucchese, nonché di sestini (1981) per le colline del chianti. tutti questi lavori descrivono generalmente superfici relitte sommitali, di solito bene individuabili nel paesaggio attuale, modellate su successioni meso-cenozoiche marine variamente corrugate. lavori più recenti sono quelli citati nella sintesi che segue1. nell’appennino umbro-marchigiano, a partire dal citato lavoro di desplanques è stata ripetutamente illustrata una superficie relitta, generalmente in posizione sommitale, denominata come “la paleosuperficie” o “paleosuperficie sommitale”2, scolpita nelle formazioni calcaree, calcareo-marnose e terrigene della successione marina giurassico-miocenica. per la definizione delle sue caratteristiche si può fare riferimento a ciccacci et al. (1985) che descrivono una superfice relitta spianata o blandamente ondulata, in forte contrasto morfologico con la accentuata pendenza dei versanti delle valli che la incidono. questa superficie è stata generalmente interpretata come un paesaggio a bassa energia di rilievo, reso relitto dai fenomeni di forte incisione innestati dal sollevamento della catena; la sua genesi è stata generalmente imputata a processi erosivi a carattere areale, realizzatisi in condizioni climatiche di tipo probabilmente arido (dramis et al., 1991; dramis, 1992). calamita et al. (1999) e coltorti e pieruccini (2000) hanno avanzato l’ipotesi che la sua realizzazione sia avvenuta a quote prossime a quelle del mare, senza peraltro esplicitarne le motivazioni. la “paleosuperficie sommitale” è stata genericamente attribuita al pliocene inferiore (ciccacci et al., 1985; dramis, 1992) sulla base dei rapporti cronologici con le fasi dell’evoluzione tettonica individuate nell’area. a conferma di questa attribuzione coltorti e pieruccini (1997) hanno precisato che in corrispondenza del bacino di spoleto la superficie è correlabile con una superficie d’erosione ricoperta da sedimenti riferibili alla parte finale del pliocene inferiore. 70 c. bosi 1 per un elenco più completo di lavori sull’argomento si rimanda a messina et al. (2002) e a coltorti e pieruccini (2000). 2 nel seguito le virgolette saranno utilizzate per indicare che questo termine viene utilizzato nel senso indicato dagli autori. tutti gli autori citati sono sostanzialmente d’accordo nel ritenere che la superficie abbia avuto un’estensione regionale, avendo lasciato le sue tracce su tutto l’appennino umbro-marchigiano. recentemente coltorti e pieruccini (2000), hanno ipotizzato che la superficie fosse originariamente estesa addirittura su tutta la penisola italiana. questa ipotesi deriva, in sostanza, dalla correlazione di tutti i lembi di spianate sommitali esistenti nell’area. nella “paleosuperficie sommitale” sono debolmente incassate altre spianate d’erosione che corrispondono agli orographic terraces di ciccacci et al. (1985) ed alle “spianate non intravallive” di nesci et al. (1992); i resti di queste spianate hanno estensione abitualmente modesta (spesso di pochi ettari) ed interessano la parte superiore dei grandi versanti che incidono la paleosuperficie. più decisamente incassata in quest’ultima è una superficie relitta a carattere regionale, costituita prevalentemente da spianate pedimentarie (dramis et al., 1991; dramis, 1992) e correlabile con la “superficie villafranchiana” di demangeot (1965), riferita al pleistocene inferiore sulla base di rapporti con alcune successioni fluvio-lacustri. entro questa superficie sono poi incassate successioni terrazzate costituite sia da superfici d’erosione, 71l’interpretazione delle superfici relitte ... sia da superfici di accumulo, del tipo di quelle descritte da nesci et al. (1992) e da cantalamessa et al. (1986). situazioni analoghe a quella dell’appennino umbro-marchigiano sono note anche nell’appennino laziale-abruzzese. in questa zona sono abbastanza diffuse superfici relitte sommitali (superfici di anzano, di m.te marine e dell’aquilente)3, con caratteristiche del tutto simili a quelle della “paleosuperficie sommitale”; altre superfici (s. di longone sabino, di alto di cacchia e di pescasseroli), incassate in quelle, potrebbero corrispondere alla citata “superficie villafranchiana” (bertini & bosi, 1978; bosi, 1989b; bosi e messina, 1991; galadini e messina, 1993; cacciuni et. al., 1995) ulteriori superfici sono quelle che si osservano sui fianchi delle valli principali, progressivamente incassate le une nelle altre. molte di queste superfici hanno carattere erosionale e sono geneticamente riconducibili ad episodi di pediplanazione connessi con la temporanea stabilità di livelli di base locali; alcune altre corrispondono a superfici di accumulo al top di sedimenti fluviali o lacustri. figura 1 – schema orografico dell’area considerata. 1, 2, 3: epicentri dei principali eventi del terremoto di colfiorito del settembreottobre 1997 (1 – annifo; 2 – cesi; 3 sellano). orographic scheme of the study area; 1, 2, 3: epicentres of main events of the colfiorito earthquake of september-october, 1997 (1annifo; 2cesi; 3sellano). 3 queste superfici sono talora rappresentate da spianate dalle quali emergono modesti rilievi a versanti di regola poco inclinati. in questi casi il termine “superficie sommitale” si riferisce non alla sola spianata, ma all’insieme spianata+rilievo. situazioni di questo tipo sono note nella valle dell’aterno (bertini e bosi, 1993), nella conca del fucino (bosi et al.,1996), nella valle del salto (bosi et al., 1989; chiarini et al., 1997), nella conca di rieti (cavinato, 1993; carrara et al., 1992) ed in quella di pescasseroli (galadini e messina, 1993), nonché nella conca di amatrice (cacciuni et al. lav. cit.). una superficie relitta sommitale con caratteristiche molto simili a quella dell’appennino umbro-marchigiano è stata riconosciuta anche nell’appennino campanolucano; anch’essa era stata inizialmente interpretata come un paleopaesaggio pianeggiante, realizzatosi più o meno contemporaneamente in tutta l’area in funzione di livelli di base regionali (brancaccio e cinque, 1988). a partire dai primi anni ’90 questa interpretazione è però sensibilmente cambiata, nel senso che all’ipotesi di un’unica unità geomorfologica è stata sostituita l’ipotesi di unità plurime, elaboratesi in tempi diversi in relazione a livelli di base locali (cinque 1992; 1995). secondo questo autore l’ipotesi iniziale deve essere accantonata, non solo per alcuni difetti logici nell’impostazione delle ricerche che ne sono alla base, ma soprattutto perché è incompatibile con l’evoluzione strutturale generalmente accettata per l’appennino meridionale. anche in questa parte della catena, nella superficie sommitale sono incassate successioni terrazzate analoghe a quelle dell’appennino laziale-abruzzese. queste successioni sono state riconosciute in varie zone fra le quali sono da citare la val d’agri (amato e dimase, 1997; di niro e giano, 1995), la valle del noce (la rocca e santangelo, 1992), la valle del tanagro (ascione, cinque e tozzi, 1992), il bacino di calvello (amato e cinque, 1992) e la valle del volturno (brancaccio et al., 2000). tornando all’appennino umbro-marchigiano, un’efficace panoramica dei problemi che si incontrano nello studio delle successioni di superfici relitte può essere delineata partendo dal confronto fra due gruppi di lavori, riguardanti la zona oggetto di questa nota. il primo gruppo (ficcarelli et al., 1997; calamita et al.,1997; calamita et al., 2000) interessa una vasta area che si estende dalla valle del topino alla dorsale m.tolagna-m.cavallo, comprendendo l’altopiano di colfiorito. in questi lavori sono individuati numerosi ed estesi lembi di superfici relitte che vengono riferiti ad un’unica planation surface correlabile con la “paleosuperficie sommitale”. le principali differenze di quota fra gruppi di lembi di questa superficie sono imputate a dislocazioni tettoniche. il secondo gruppo di lavori (messina et al., 1999; messina et al., 2002)4 riguarda un’area che presenta un’ampia zona di sovrapposizione rispetto a quella considerata nel primo gruppo di lavori. il quadro delle superfici relitte che viene fornito è però sensibilmente diverso. nel settore occidentale, corrispondente all’altopiano di colfiorito, i lembi riconosciuti sono stati attribuiti a otto ordini distinti, distribuiti all’incirca fra i 750 ed i 1200 metri di quota; nel settore orientale, corrispondente a parte della dorsale m.cavallo-m.tolagna, sono distinti tre ordini di superfici situati fra 1100 e 1400 metri di quota circa. secondo gli autori, i tre ordini riconosciuti sulla dorsale sono riferibili a un paleopaesaggio analogo alla “paleosuperficie sommitale”. a questa superficie potrebbero essere riferiti anche i più alti fra gli ordini di superfici relitte riconosciute nell’altopiano; le differenze di quota con le superfici della dorsale potrebbero essere imputabili a dislocazioni tettoniche. il contrasto fra i due gruppi di lavori non è riconducibile ad una semplice divergenza di opinioni sul numero degli ordini di superfici, ma rimanda a problematiche più generali che riguardano i criteri applicati nella individuazione e nella correlazione delle superfici relitte. nel primo gruppo di lavori questi criteri non sono precisati; non sono quindi espliciti i motivi che hanno portato alla definizione di un’unica superficie relitta a dispetto del fatto, indicato da messina et al. (1999) e confermato dall’analisi svolta nell’ambito del presente lavoro, che nel paesaggio attuale possono essere agevolmente riconosciute successioni di lembi di spianate moderatamente incassate l’una nell’altra. appare quindi chiaro che con la planation surface si è inteso definire un paleopaesaggio “policiclico” comprendente questi lembi, interpretati come effetti di fenomeni di spianamento a carattere locale verificatisi nell’ambito di una fase morfogenetica sostanzialmente unitaria. nel secondo gruppo di lavori i criteri adottati sono più analitici, in quanto quelli che vengono considerati sono i singoli lembi osservati e non un insieme di lembi già interpretati come facenti parte di una stessa unità morfologica. questa impostazione discende chiaramente dall’ipotesi che: (i) i singoli lembi siano geneticamente distinti e suscettibili di correlazione in quanto connessi con la stabilità di livelli di base più generali e (ii) solo i lembi più alti possano essere interpretatati come elementi della “paleosuperficie”. le marcate diversità delle interpretazioni fornite dai due gruppi di autori devono essere ricercate nei modelli genetici che ne sono alla base e nei metodi di studio che ne derivano. 33.. mmooddeellllii ggeenneettiiccii 33..11 llaa ““ppaalleeoossuuppeerrffiicciiee ssoommmmiittaallee”” la maggior parte degli autori che si sono interessati dell’argomento ha ipotizzato che i lembi relitti attribuiti a questa superficie configurino un elemento geomorfologico sostanzialmente unitario; esso corrisponderebbe infatti ad un paleopaesaggio pianeggiante che, nell’ambito dell’area considerata da ciascun autore, si sarebbe originato in una stessa fase morfogenetica ed avrebbe presentato ovunque caratteristiche geomorfologiche analoghe a quelle dei lembi attualmente osservabili. questo paesaggio sarebbe quello esistente all’inizio dell’approfondimento del reticolo idrografico, comunemente riferito al pliocene. in appennino i casi in cui i lembi di spianate presentano una contiguità geometrica tale da comprovare direttamente l’unitarietà della “paleosuperficie sommitale” sono decisamente scarsi. nella maggior parte dei casi questa unitarietà, nell’area considerata da ciascun 72 c. bosi 4 per brevità, nel seguito la citazione dei due gruppi di lavori farà riferimento soltanto a quelli di ficcarelli et al. (1997) e messina et al. (1999) che esprimono compiutamente le valutazioni dei due gruppi di ricercatori. 73l’interpretazione delle superfici relitte ... autore, può quindi essere affermata solo sulla base di una correlazione fra le varie spianate sommitali. questa correlazione, data la mancanza pressochè totale di riscontri stratigrafici, è fondata sostanzialmente su due fatti: a) i lembi di spianate hanno una posizione sommitale; b) le quote dei lembi tendono ad essere relativamente uniformi su aree anche vaste. il valore probatorio di questi fatti deve essere considerato con molta cautela. il primo non ha alcun significato cronologico, se non quello, scontato, che ciascuno dei lembi di spianate sommitali è più antico di tutti gli eventuali lembi in esso incassati. anche il fatto che si tratta di elementi morfologici che precedono la fase di approfondimento del reticolo connessa con il forte sollevamento tettonico, non è che un vincolo “ante quem”, insufficiente per una convincente valutazione cronologica il secondo fatto (la relativa costanza delle quote) può portare a delineare una superficie unitaria solo se si postula che eventuali differenze di quota fra lembi di spianate sommitali, anzichè essere riconducibili all’incassamento di più superfici d’erosione, siano da imputare a dislocazioni tettoniche. e’ evidente che questo postulato è affetto da una marcata circolarità in quanto è fondato sulla supposta originaria unitarietà della paleosuperficie, che è proprio l’elemento in discussione. d’altra parte, nella correlazione fra le diverse spianate sommitali si deve tener conto anche del fatto, non trascurabile, che i lembi osservabili rappresentano generalmente una porzione molto piccola dell’area che si suppone essere stata interessata da quella superficie; tanto piccola che in molti settori della catena il campione rappresentato dai lembi relitti deve addirittura essere considerato come statisticamente non significativo nei riguardi della ricostruzione di qualsivoglia paesaggio originario di appartenenza5. e’ poi importante notare che correlare le spianate sommitali solo perché si tratta delle spianate più antiche (in altre parole correlare le spianate sommitali in quanto sommitali) porterebbe ad estendere la “paleosuperficie” a tutte le zone nelle quali sono presenti spianate sommitali, il che significa, di fatto, a tutto l’appennino. di conseguenza accettare questa correlazione porta, quasi inevitabilmente, ad accettare l’ipotesi di coltorti e pieruccini (2000) sulla continuità della superficie su tutta la penisola italiana. si tratta evidentemente di un’ipotesi che ha importanti conseguenze sulla ricostruzione dell’evoluzione tettonica dell’appennino, in relazione sia agli aspetti metodologici delle ricerche, sia ai vincoli che verrebbero posti alla ricostruzione stessa. essa farebbe infatti della “paleosuperficie sommitale”, da un lato, un prezioso orizzonte di riferimento che permetterebbe di valutare con continuità l’entità del sollevamento su tutta la penisola e, dall’altro, porterebbe ad ammettere un periodo di generale stabilità tettonica di durata tale da permettere una fase erosiva6 in grado di “piallare” l’intero appennino. l’ipotesi avanzata, per quanto suggestiva, appare però poco credibile. essa deve fare i conti, infatti, sia con le citate critiche di cinque (1992; 1995), sia con riserve a carattere più generale. una prima riserva (alla quale ha accennato anche questo autore) è che, a parte la “paleosuperficie sommitale”, nell’evoluzione della catena non sono noti altri indizi di quella fase di stabilità tettonica che essa presupporrebbe. questa circostanza è indirettamente provata dal fatto che l’eventuale eliminazione di questa fase di spianamento non pregiudica in alcun modo la congruenza degli attuali modelli dell’evoluzione tettonica della catena come, ad esempio, quello di calamita et al. (2000) per l’appennino centrale. altrettanto difficile è indicare nelle successioni sedimentarie dei bacini marini che nel pliocene delimitavano la dorsale appenninica (lato tirrenico e lato adriatico), attualmente affioranti ai piedi della catena, quelli che dovrebbero essere i depositi correlativi di una fase erosiva commisurata all’entità dello spianamento invocato7. e’ chiaro, inoltre, che estendere la paleosuperficie sommitale a tutto l’appennino significa aumentare enormemente i casi in cui le differenze di quota fra lembi di spianate sommitali devono essere imputati a dislocazioni tettoniche. l’argomentazione che è alla base dell’ipotesi di una superficie unitaria su tutta la penisola è quindi doppiamente circolare: nei riguardi del rapporto fra paleosuperficie e fase di stabilità tettonica che l’avrebbe generata, e nei riguardi del rapporto fra differenze di quote e dislocazioni tettoniche. un po’ come dire che la fase di stabilità tettonica è dimostrata dalla unitarietà della superficie e che la sua eventuale non-unitarietà geometrica deve essere imputata a dislocazioni tettoniche. un po’ paradossalmente, è quindi proprio la larga diffusione delle spianate sommitali che rappresenta l’elemento di maggior debolezza nei riguardi dell’ipotesi che tutti i lembi siano il risultato di una stessa fase erosiva. per ridurre il peso di questa argomentazione, in modo da poter salvare la possibilità di correlare le spianate sommitali in quanto sommitali e poste a quote simili, si potrebbe pensare di “regionalizzare” la paleosuperficie sommitale. si potrebbe, cioè, rinunciare all’idea di una superficie estesa su tutto l’appennino ripiegando su estensioni più modeste, separando ad esempio una paleosuperficie marchigiana da una laziale-abruzzese o da una umbra. le possibilità di successo di una simile operazione appaiono però piuttosto problematiche in quanto sarebbe necessario, da un lato, tracciare limiti geologicamente motivati fra le diverse aree e, dall’altro, assegnare alle paleosuperfici presenti in ciascuna di queste aree una diversa collocazione temporale ed uno specifico significato tettonico, pena la ricaduta nell’ipotesi della superficie unitaria a scala peninsulare. in un panorama interpretativo così problematico l’argomento che riveste il peso maggiore a favore dell’ipotesi di una superficie unitaria, regionale o peninsulare 5 ovviamente a meno che non si postuli la planarità del paesaggio, ricadendo così nella circolarità dell’argomentazione 6 anche se non è possibile formulare valutazioni quantitative al riguardo, l’entità della discordanza della “paleosuperficie” con le successioni sedimentarie che ne sono erose induce a ritenere quanto meno verosimile che si sia trattato di un fenomeno che ha asportato un volume considerevole di materiali, di durata certamente non breve. 7 depositi di questo tipo potrebbero essere quelli descritti da cantalamessa et al., (1986) peraltro limitati alle marche meridionali 74 c. bosi che sia, resta il fatto che questa sembra corrisponde all’unico modello evolutivo in grado di spiegare i fatti osservati. la prima obiezione che viene fatta al tentativo di negare l’unitarietà della superficie è, infatti, che non si vede in quale altro modo si possa spiegare la situazione osservata, visto che la distribuzione di lembi di spianate sommitali a quote relativamente uniformi non può essere casuale. vale quindi la pena di esplorare la possibilità di schemi genetici alternativi, che siano in grado di spiegare questa distribuzione senza ricorrere all’ipotesi della superficie unica. un tentativo in questo senso può essere effettuato partendo dalle seguenti due circostanze. a) l’evoluzione geomorfologica di gran parte dell’appennino può essere schematicamente divisa in due parti: la prima, essenzialmente pliocenica, comprende una serie di fasi erosive che hanno interagito con la strutturazione della catena; la seconda corrisponde al marcato approfondimento del reticolo conseguente al successivo forte sollevamento. b) in un’evoluzione morfologica dominata dall’erosione, le forme più conservative sono quelle planari e suborizzontali; questa valutazione è avvalorata anche dal fatto che la maggior parte delle attuali superfici relitte è di questo tipo. queste due circostanze, considerate congiuntamente, inducono a ritenere che: le forme originatesi nella prima fase evolutiva e “fossilizzate” ad opera della seconda siano rappresentate prevalentemente da spianate; queste spianate siano disposte di preferenza in posizione sommitale; questa posizione possa essere diversa da quella originaria perché la continua sovrimpressione di forme di erosione può aver obliterato altre spianate (non necessariamente sommitali) poste originariamente a quote anche più alte. la distribuzione plano-altimetrica delle spianate sommitali nel paesaggio attuale verrebbe quindi ad essere sostanzialmente determinata dalle quote attuali dei maggiori rilievi: è quindi inevitabile che là dove queste quote sono contenute in intervalli relativamente ristretti (come succede in molte zone non soltanto appenniniche) i lembi delle spianate sommitali abbiano anch’esse quote relativamente uniformi, creando l’impressione di essere riconducibili ad un’unica “paleosuperficie sommitale”. in questa prospettiva la problematica genetica di questa superficie verrebbe quindi ad avere aspetti in comune con la vecchia questione della gipfelflur (penck, 1955)8, in quanto legata anch’essa alla tendenza delle sommità dei rilievi ad assumere quote relativamente uniformi su vaste aree. uno schema che esemplifica quanto ora esposto è quella delineato nella figura 2, con una successione di quattro paesaggi incassati l’uno nell’altro, profondamente incisa dall’erosione prodotta dal sollevamento della catena. dallo schema appare chiaro che i lembi di superfici relitte più o meno pianeggianti, anche se collocati in un ristretto intervallo altimetrico, non rappresentano affatto quello che resta di un’unica paleosuperficie pianeggiante; essi sono invece il risultato di una storia erosiva che, grazie alla stabilità delle forme planari ed alla relativa similitudine di quota della sommità degli attuali rilievi, ha portato a conservare a quote simili lembi di spianate di età diversa. allo schema di fig.2 si potrebbe obiettare che i quattro paesaggi fittizi che vi sono rappresentati corrispondono a morfologie di comodo, miranti a delineare scenari favorevoli all’ipotesi proposta. in realtà non è così, visto che a risultati analoghi si arriva partendo da qualunque insieme di paesaggi incassati l’uno nell’altro, purchè siano verificate due condizioni: (i) che i paesaggi comprendano superfici pianeggianti diffuse su tutta l’area considerata e (ii) che i dislivelli fra di esse siano molto minori di quelli che separano le spianate relitte presenti entro le valli che incidono la “paleosuperficie figura 2 – schema evolutivo che dimostra la possibilità che spianate sommitali a quote analoghe non siano indicative di una “paleosuperficie sommitale” geneticamente unitaria. 1, 2, 3, 4 : successione di paesaggi pre-sollevamento; 5 paesaggio attuale; i, ii, iii, iv ordine delle spianate riferito alla successione dei paesaggi 1-4. n.b. per ciascun paesaggio non sono stati considerati gli effetti del rimodellamento relativo ai paesaggi più recenti. evolutionary scheme that demonstrates the possibility that summit surfaces at a similar altitude are not indicative of one genetically unitary surface. 1, 2, 3, 4: flights of landscapes; 5-present landscape; i,ii, iii, iv order of the planation surfaces referred to flights 1-4. n.b. for each landscape, the effects of remodelling regarding more recent landscapes have not been considered. 8 si tratta, come è noto, dell’ipotesi che la relativa uniformità delle quote dei rilievi in ampi settori di catena potessero essere dovuti all’esistenza di una fantomatica originaria superficie pianeggiante, corrispondente all’inviluppo delle cime. 75 sommitale”. ambedue queste condizioni sono del tutto compatibili con uno scenario evolutivo caratterizzato, per l’appennino, dalla forte accelerazione dell’erosione provocata dal sollevamento. le principali differenze fra l’ipotesi di una “paleosuperficie sommitale” geneticamente unitaria degli autori ed il modello evolutivo proposto risiede sostanzialmente nelle caratteristiche del paesaggio esistente all’inizio dell’approfondimento del reticolo idrografico e nel ruolo che esso riveste nella ricostruzione della componente verticale delle dislocazioni tettoniche. secondo la prima ipotesi si trattava di un paesaggio pianeggiante, diffuso a scala regionale e, almeno secondo alcuni autori (v. cap.2), originatosi a quote prossime a quelle del mare, suscettibile di fornire un ottimo orizzonte di riferimento per ricostruzioni tettoniche. secondo il modello proposto si trattava invece di un paesaggio non definibile sulla base della morfologia attuale: di esso si può solo dire che doveva comprendere lembi di spianate originatesi nel corso di tutta l’evoluzione geomorfologica precedente, alcune delle quali potevano essere anche più antiche (e più alte) di quelle attualmente conservate. tenendo conto che questa parte dell’evoluzione è interamente precedente alla parte più intensa fase del sollevamento, si può tutt’al più ritenere che il paesaggio fosse probabilmente meno accidentato di quello attuale, senza che sia però possibile alcun riferimento al corrispondente livello del mare. la possibilità di utilizzare la “paleosuperficie sommitale” nelle ricostruzioni tettoniche viene quindi ad essere notevolmente ridimensionata. lo schema evolutivo prospettato in fig. 2 non esclude ovviamente che in appennino possano esistere paleopaesaggi sommitali geneticamente unitari anche estesi; esso porta solo a negare che tutti gli attuali lembi di spianate sommitali siano necessariamente riconducibili ad un unico paesaggio pianeggiante. ipotesi di paesaggi sommitali geneticamente unitari dovrebbero, di conseguenza, essere accettate solo nei casi in cui si disponga di elementi di valutazione ragionevolmente probanti, diversi ovviamente dall’assunto “a priori” della superficie unica. 33..22 llee ssuucccceessssiioonnii tteerrrraazzzzaattee dalla sintesi degli studi riportata nel capitolo 2, emerge che situazioni rappresentate da successioni terrazzate di superfici relitte, spesso incassate in lembi di antiche spianate d’erosione, sono diffuse in tutta la catena appenninica. ciò dimostra che l’approfondimento del reticolo non si è realizzato in modo continuo, ma con alternanze di fasi di incisione e fasi di spianamento che si sono realizzate, non soltanto nell’intervallo di tempo nel quale si sono realizzate le successioni di terrazzi alluvionali generalmente presenti nella parte inferiore dei versanti, ma durante tutta l’evoluzione morfologica che ha portato al paesaggio attuale. anche senza entrare nell’esame dei fenomeni che sono alla base di questa alternanza, appare ovvio che la loro generalità alla scala dell’intera catena non può che indicare una forte influenza climatica. una situazione che rappresenta nel modo più completo l’assetto delle successioni terrazzate nelle marche, senz’altro la zona appenninica più conosciuta sotto questo profilo, è quella sintetizzata in nesci et al. (1992) riportata nella figura 3. da questa figura sembra potersi desumere che, al di là delle distinzioni terminologiche, il fenomeno del terrazzamento è sostanzialmente consistito nel progressivo incassamento di spianate la cui estensione complessiva si è progressivamente ridotta nel corso dell’approfondimento del reticolo, fino ai terrazzi alluvionali conservati nella parte inferiore dei versanti. sembra potersi desumere anche che le spianate più antiche (“spianate non intravallive” corrispondenti agli oroghraphic terraces di ciccacci et al.,1985) dovevano corrispondere a larghissime depressioni pianeggianti, incassate nella “paleosuperficie sommitale”. la verosimiglianza di questa ipotesi appare piuttosto dubbia, soprattutto per la difficoltà di spiegare in modo convincente la genesi di queste spianate. essa non può, infatti, essere imputata a fenomeni di erosione fluviale, dal momento che mancano completamente altri indizi di attività dei fiumi corrispondenti; difficile pure pensare a soli processi pedimentari di questa importanza, ripetuti durante tutto il processo di escavazione. figura 3 – sezioni morfologiche trasversali nell’area di fossombrone. t3, t2, t1 terrazzi poligenici; te terrazzi d’erosione; se spianate non intravallive (da nesci et al. 1992, semplificata). morphological sections in the fossombrone area. t3, t2, tlpoligenic terraces; teerosion terraces: senot intravallies surfaces. (by nesci et al.1992, simplified). l’interpretazione delle superfici relitte ... un altro fatto che lascia perplessi è che, nonostante l’estensione di questi ipotetici spianamenti, l’area dei singoli lembi tende ad essere sempre molto limitata. un modello evolutivo che sembra in grado di spiegare in modo più convincente la grande estensione delle aree nelle quali sono conservati lembi, anche modesti, di uno stesso ordine di spianate è quello schematizzato nella figura 4. secondo questo schema i lembi di superfici relitte sarebbero da riferire non ad un’unica spianata connessa con la stabilità del livello di base della corrispondente larghissima vallata, ma a spianate sviluppatesi sui fianchi di un insieme di valli distinte, che sono espressione di uno stesso stadio di approfondimento del reticolo. si tratterebbe quindi di effetti connessi con la stabilità di livelli di base plurimi, accumunati dal fatto di essere significativamente più bassi di quelli corrispondenti alle spianate immediatamente più antiche e più alti di quelli delle spianate immediatamente più recenti. i limiti delle zone nelle quali sono conservati lembi di spianate di uno stesso ordine corrisponderebbero quindi ai limiti delle aree sulle quali ha agito il sistema di valli appartenenti ad uno specifico stadio di approfondimento del reticolo. e’ da osservare che lo schema evolutivo proposto, se da un lato fornisce una spiegazione più convincente dei fatti osservati, dall’altro complica notevolmente l’interpretazione delle successioni terrazzate di superfici relitte. l’inviluppo dei lembi relitti appartenenti ad uno stesso ordine di superfici dovrebbe infatti essere assimilato non ad una superficie pianeggiante e suborizzontale, ma ad una morfologia più o meno irregolare la cui unica caratteristica certa è quella di presentare quote decrescenti verso i livelli di base. nel caso di successioni di più superfici incassate l’una nell’altra possono di conseguenza aumentare notevolmente le difficoltà che si incontrano sia nel definire correlazioni fra i lembi osservati, sia nel ricavare indicazioni sulle deformazioni tettoniche partendo dalla attuale distribuzione plano-altimetrica degli stessi lembi. per inciso, si può anche osservare che, adottando lo schema di fig.4, le distinzioni terminologiche proposte nel citato lavoro di nesci et al. (terrazzi vallivi poligenici, terrazzi d’erosione, spianate non intravallive), come anche quelle analoghe di altri lavori sull’argomento (v. ad esempio la carta geomorfologica allegata a dramis et al., 1992 ) potrebbero perdere gran parte delle loro motivazioni; tutte le spianate comprese fra quelle sommitali ed i sedimenti alluvionali sospesi sui fondovalle potrebbero, infatti, essere esaurientemente definite dalla loro posizione ordinale e da una precisazione in merito alla loro origine (erosionale o di accumulo). 44.. mmeettooddii ddii ssttuuddiioo in relazione ai metodi seguiti negli studi sulle superfici relitte è opportuno considerare soprattutto i criteri di delimitazione dei lembi di superfici osservati e i criteri di correlazione degli stessi. i criteri di delimitazione devono fare i conti con un’inevitabile soggettività legata a diverse circostanze, fra le quali sono da citare le seguenti: tutte le superfici relitte sono più o meno rimodellate come è dimostrato, fra l’altro, dall’assenza pressoché totale di coltri colluviali e di suoli; la distinzione fra rimodellamento ed incassamento di altre superfici può talora essere piuttosto opinabile; salvo casi eccezionali, i lembi di spianate non sono delimitati da cigli netti, cartografabili con precisione, ma da convessità più o meno pronunciate che raccordano le spianate ai versanti che le intersecano. la soggettività della delimitazione può avere conseguenze importanti sui risultati che si possono ottenere. largheggiare nella delimitazione, ad esempio, finisce inevitabilmente per aumentare in modo rilevante l’area attribuita a resti di paesaggi relitti, contribuendo ad aumentare in modo gratuito la verosimiglianza di ricostruzioni che possono invece essere molto aleatorie; porta inoltre ad ampliare l’intervallo di quota nel quale si sviluppa la superficie e, quindi, ad ipotizzare morfologie originarie più ondulate. d’altra parte, delineare lembi più ristretti (fino a considerare soltanto le quote più alte dei singoli lembi), orienta di fatto verso l’ipotesi di morfologie originarie più piatte, che possono incoraggiare ipotesi di correlazioni su basi prevalentemente altimetriche. più complessi sono i problemi relativi alla correlazione fra i diversi lembi osservati, problemi che sono diversi da quelli già analizzati a proposito delle superfici sommitali (par. 3.1) considerazioni su questo argomento possono prendere le mosse dai criteri indicati in messina et al. (1999), ripresi da bosi et al. (1996), che sono fondati sulle seguenti caratteristiche: quote dei diversi lembi; spaziatura altimetrica fra coppie di superfici apparte76 c. bosi figura 4 – schema evolutivo che riconduce i lembi relitti di successioni terrazzate all’approfondimento “per fasi” di un reticolo idrografico costituito da insiemi di incisioni di modesta entità. n.b. per le tre fasi più antiche non sono state evidenziate le fasi di incisione che hanno terrazzato le spianate di fondovalle dando origine alla successione dei diversi ordini di superfici. evolutionary scheme that leads the planation surfaces of terraces flights to a deepening of a hydrographic network made up by a group of modest incisions. n.b. for the three oldest phases, the phases of incisions that have terraced the valley bottom, giving origin to successions of different surfaces orders, have not been highlighted. nenti a successioni diverse, tenuto conto della loro pendenza originaria; posizione nell’ambito delle diverse successioni. esperienze effettuate in varie zone appenniniche sembrano indicare che questi criteri debbano essere rivisti, soprattutto per il fatto, già ricordato nel paragrafo 3.2, che la pendenza delle superfici originarie non è nota. esiste quindi il rischio, già ventilato, che si finisca con l’adottare un modello rappresentato da una serie di superfici sostanzialmente pianeggianti e suborizzontali progressivamente incassate l’una nell’altra, modello che è privo di adeguate motivazioni. un’altra considerazione che induce alla cautela nella applicazione dei criteri sopra ricordati riguarda il ruolo della posizione ordinale delle superfici nelle diverse successioni. e’ infatti ovvio che questa posizione può essere di ausilio nella correlazione fra i diversi lembi solo a patto che si possano escludere obliterazioni tali da alterare le successioni originarie, annullando le tracce di uno o più ordini di superfici. tenuto conto di queste circostanze e dei modelli evolutivi riportati nel cap.3, nello studio della zona considerata è stata seguita una procedura che può essere sintetizzata come segue. a) sono stati considerati tutti i lembi di spianate d’erosione, da suborizzontali a poco inclinate, che possono essere interpretate come tracce di antiche morfologie realizzatesi con riferimento a livelli di base diversi da quelli attuali. i limiti dei singoli lembi sono stati tracciati in corrispondenza del punto di massima curvatura della convessità che separa la spianata dal sottostante versante, eliminando l’effetto topografico dei più evidenti fenomeni di rimodellamento. b) allo scopo di definire nel modo più affidabile possibile la successione degli eventi di spianamento che hanno interessato la zona, è stato inizialmente individuato un certo numero di “successioni-base”, ciascuna delle quali è rappresentata da due o più spianate raccordate da versanti geometricamente continui, in modo da minimizzare il rischio di trascurare gli effetti di dislocazioni tettoniche. l’insieme delle “successioni-base” ha portato alla elaborazione di una “successione-tipo”, che dovrebbe corrispondere alla successione degli eventi di spianamento e, quindi, agli ordini di superfici da considerare9. c) si è proceduto poi ad una correlazione dei singoli lembi cartografati con la successione-tipo, fondata sui rapporti plano-altimetrici riferiti a scenari paleomorfologici ritenuti ragionevoli. in concreto si potrebbe dire che il quadro delle correlazioni effettuate ha corrisposto ad un processo di best fitting fondato sui vincoli derivanti dalla successione-tipo, dalla distribuzione plano-altimetrica dei lembi osservati e dalle dislocazioni tettoniche cronologicamente caratterizzate. i lembi di attribuzione problematica sono stati opportunamente evidenziati; quelli per i quali il livello di incertezza era troppo elevato sono stati definiti come “non correlabili”. e’ chiaro che la procedura delineata conserva ancora notevoli margini di opinabilità, in relazione sia alla ricostruzione della successione tipo, sia alla attribuzione dei singoli lembi di spianate agli ordini di questa successione. il metodo sembra comunque rappresentare un certo progresso non foss’altro perchè, chiarendo le motivazione delle diverse scelte, facilita la valutazione sull’attendibilità e sulla verosimiglianza della ricostruzione effettuata. 55.. llaa ssuucccceessssiioonnee ddeellllee ssuuppeerrffiiccii rreelliitt-ttee nneellll’’aarreeaa ssttuuddiiaattaa nella zona esaminata, i lembi di superfici relitte (v. carta allegata) sono relativamente numerosi ma di dimensioni generalmente modeste (raramente raggiungono 0.5-1.0 kmq), tanto che si può stimare che la superficie complessiva dei lembi osservati rappresenti mediamente alcuni percento dell’area totale. i lembi sono però distribuiti in modo tale da rendere possibile l’individuazione di un discreto numero di “successionibase” (par.4); fra le più rilevanti ai fini dello studio si possono citare quelle delle zone di m.tito e di m.camorlo, rispettivamente nel settore meridionale e settentrionale dell’area. l’insieme delle successioni-base è stato integrato in una “successione-tipo” costituita da otto ordini di superfici. per queste superfici l’abituale indicazione per ordine numerico (i, ii, iii …. ordine) è stata sostituita da una denominazione analoga a quella usata nella litostratigrafia; ogni superficie è stata cioè contraddistinta con un nome di località, tendenzialmente quella nella quale la essa è più evidente. per le superfici più antiche, riconosciute solo alla sommità dei maggiori rilievi del settore orientale dell’area considerata, è stato utilizzato il termine “gruppo delle spianate sommitali” per esprimere la valutazione che queste superfici, pur appartenendo al paleopaesaggio sul quale si è esplicata l’erosione conseguente al sollevamento, possono non appartenere ad una stessa fase morfogenetica (v. par. 3.1). altre informazioni utili alla interpretazione della carta allegata sono quelle sotto riportate. 1) nell’ambito del “gruppo delle spianate sommitali” l’appartenenza ad un’unica superficie originaria può essere ipotizzata solo per gli estesi lembi conservati alla sommità dei rilievi compresi fra m.fema, e m.cavallo, nel settore sud-orientale dell’area considerata, date le modeste distanze che li separano e l’assenza di importanti incisioni interposte. nessuna correlazione può invece essere ipotizzata fra questi lembi e quelli conservati nelle altre zone. 2) la superficie di m.tito è ben rappresentata alla sommità dei blandi rilievi che caratterizzano il settore occidentale dell’area considerata, ad ovest della dorsali di m.tolagna e di m.prefoglio-m.scalette; essa sembra però aver interessato anche un’ampia zona in corrispondenza della valle del chienti e l’altopiano di m.lago. il suo incassamento nella superficie di m.peletta ed in quelle sommitali si può osservare piuttosto chiaramente nel settore meridionale dell’area considerata. questa superficie è la più recente fra quelle che precedono l’impostazione della depressione tettonica nella quale è contenuta la successio77 9 si può osservare che, come indicato in altri lavori (carraro e ferrarino, 1981), questa successione può essere considerata l’equivalente in campo morfologico delle usuali successioni stratigrafiche (“successione morfosequenziale” in bosi, 1989a). l’interpretazione delle superfici relitte ... ne di cesi-colle curti (ficcarelli et al., 1997). dato che, secondo questi autori, la base di questa successione è riferibile al pleistocene inferiore (più antico di un milione di anni circa) il completamento della superficie di m.tito dovrebbe essere riferito pliocene o, tutt’al più, alla parte basale del pleistocene inferiore. 3) la superficie di rasenna è sviluppata a tetto della parte superiore della successione pleistocenica di cesi-collecurti, studiata da ficcarelli et al. (lav. cit.) e precisata da messina et al. (1999), contenente tephra datati a circa 430.000 anni. 4) la superficie di cavallara, definita sulle alture ad w della palude di colfiorito, è rappresentata nella parte meridionale dell’area considerata ad un sistema di fondovalle sospesi rispetto alle valli attuali. 5) la superficie di borgo corrisponde alla superficie sommitale di un terrazzo fluviale che, a sse del piano di colfiorito, è incassato sia nella superficie di rasenna, sia in quella di cavallara. 6) la superficie di casale paolucci corrisponde al top di conoidi ed a lembi di terrazzi (di erosione e di accumulo)10, sospesi sui fondovalle o su sporadici lembi di terrazzi alluvionali recenti che non sono stati considerati. si deve anche precisare che, nell’interpretazione dei lembi di superfici relitte ad e di colfiorito, si è tenuto conto delle importanti faglie ubicate al piede delle dorsali m.prefoglio-m.scalette e m.tolagna, la cui attività si sarebbe protratta fino all’attuale, come dimostrato dalle dislocazioni verificatesi in occasione del recente terremoto di colfiorito (cello et al., 1997; cinti et al., 1999). secondo altri autori (basili et al., 1998; messina et al., 1999), invece, l’attività di queste faglie si sarebbe praticamente arrestata nel pleistocene medio, ragion per cui esse dovrebbero aver interessato solo le superfici più antiche di quella di rasenna. analoga considerazione si è riservata anche alle faglie che interessano la zona ad ovest della dorsale m.acuto-m.trella che mostrano indizi morfologici di dislocazioni riferibili al pleistocene medio-superiore11. i risultati sintetizzati nella carta differiscono da quelli di ficcarelli et al. (1997) in modo radicale: tutte le superfici che vi compaiono costituiscono infatti differenziazioni dell’unica superficie sommitale individuata dagli autori. i risultati ottenuti sono sensibilmente diversi anche da quelli di messina et al. (1999), oltre che per la diversa interpretazione delle spianate sommitali, per il numero minore di superfici riconosciute nell’altopiano di colfiorito (5 invece di 8) e per la posizione stratigrafica della “superficie di m.tito”, incassata nelle superfici più antiche anziché correlabile con esse. 66.. sscchheemmaa eevvoolluuttiivvoo sulla base dei dati raccolti e delle interpretazioni schematizzate nella carta allegata e precisate nel capitolo precedente, la successione delle fasi erosive che ha interessato la zona può essere divisa in due parti. nella prima, una successione di eventi di spianamento, cronologicamente non precisabili, ha dato origine al gruppo delle “spianate sommitali”; nella seconda si è prodotta una sequenza di almeno sette eventi di spianamento, testimoniati dalle superfici comprese fra quella di colle argentiera e quella di casale paolucci, seguiti da altrettante fasi di escavazione. la successione di tutti questi eventi erosionali si è manifestata in un contesto tettonico determinato, oltre che da un sollevamento generalizzato plio-quaternario (v. cap.2), dall’attività della importante struttura tettonica corrispondente al bordo occidentale del gruppo montuoso m.fema-m.pennino (faglia di m.tolagna e faglia m.prefoglio-m.scalette già citate) (calamita et al., 1997). le modalità con le quali si è realizzata l’interazione erosione-tettonica possono essere sintetizzate come segue. a) dopo la successione degli eventi di spianamento responsabili della formazione del gruppo delle “spianate sommitali”, due distinte alternanze incisionespianamento hanno dato origine alle superfici di colle argentiera e di m.peletta. la distribuzione dei corrispondenti lembi relitti non fornisce particolari informazioni sull’evoluzione del paesaggio nel corrispondente intervallo di tempo; appare comunque probabile che le fasi erosive siano state di entità piuttosto modesta. b) una successiva, e ben più importante, fase erosiva ha portato alla individuazione di due distinti gruppi di rilievi (m.fema-m.tolagna a sud e m.camorlom.pennino a nord), separati da una larga depressione, con asse all’incirca corrispondente all’attuale valle del chienti (v. fig.5). questa fase corrisponde verosimilmente all’inizio del forte sollevamento generalizzato riconosciuto in tutto l’appennino centrale. essa è stata seguita da un importante episodio di spianamento che ha dato origine alla superficie di m.tito, profondamente incassata nelle superfici precedenti e sviluppata in tutta la parte occidentale dell’area considerata, nonché nelle zone corrispondenti alla valle del chienti ed all’altopiano di m. lago. questa fase di spianamento non sembra aver risentito della attività della faglia m.prefoglio-m.scalette. c) la successiva alternanza incisione-spianamento ha dato origine alla superficie di rasenna, moderatamente incassata in quella di m. tito, che mostra una distribuzione sostanzialmente limitata alla parte occidentale dell’area ed alla zona di m. lago12. la diferenza fra questa distribuzione e quella della superficie di m.tito suggerisce una discontinuità del panorama erosivo, probabilmente connessa con l’attività della citata faglia m.prefoglio-m.scalette. d) l’evoluzione geologica successiva alla superficie di rasenna appare condizionata dallo sbarramento del 78 c. bosi 10 nella carta allegata sono indicati solo i lembi più importanti. 11 questa valutazione è ricavata da un’analisi dei rapporti fra elementi morfologici specifici e paesaggi relitti, che sarà oggetto di una imminente pubblicazione. 12 a meno che la superficie di rasenna non possa essere riconosciuta anche nei lembi cartografati come “non attribuibili” nella zona di m.barbontile, nel qual caso la situazione di m.lago dovrebbe essere allargata verso sud. 13 secondo messina et al. (lav.cit.) allo sbarramento ha collaborato anche una grande frana verificatasi in corrispondenza del margine orientale del piano di colfiorito. 79 reticolo ad opera della faglia m. prefoglio-m. scalette13, e dalla impostazione, nell’altopiano di colfiorito, di due distinti bacini separati dalla sella de la pintura (testata del percanestro, a sw del m. tolagna). vengono così a configurarsi tre distinti bacini (colfiorito, m. lago e percanestro), ciascuno caratterizzato da una propria evoluzione, legata peraltro ad un’analoga successione di alternanze incisione-spianamento. e) la parte più recente dell’evoluzione geomorfologica si collega direttamente a quella in atto, determinata dalla forte approfondimento dei bacini del chienti, del topino e del nera e dall’evoluzione endoreica degli altopiani di colfiorito e di m.lago, influenzata da vistosi fenomeni carsici. per l’altopiano di colfiorito appare inoltre evidente il ruolo svolto, anche in questa fase, dalla struttura corrispondente alla faglia m.prefoglio-m.scalette. ai fini della ricostruzione della evoluzione geologica dell’area dovrebbero, ovviamente, essere considerate anche le indicazioni fornite dalle successioni sedimentarie esistenti nell’area. rinviando ad un successivo lavoro lo sviluppo di questo argomento, ci si limita in questa sede a ricordare che le successioni di interesse più generale sono quelle contenute nelle principali depressioni, descritte da ficcarelli et al. (1997) e da messina et al. (1999), cronologicamente collocabili fra gli eventi indicati ai punti b) e c). altre successioni di un qualche rilievo sono quelle immediatamente sottostanti alle superfici di borgo e di c.paolucci. lo schema dell’evoluzione geologica così delineato sembra suggerire che l’inizio del sollevamento generalizzato dell’area sia da porre in un pliocene piuttosto inoltrato, piuttosto che nella parte superiore del pliocene inferiore come ritenuto da coltorti e pieruccini (2000). questa valutazione deriva sia dalla non-significatività della situazione della zona di spoleto, descritta da coltorti e pieruccini, 1997), sia sul verosimile assunto di una durata non breve degli eventi che, oltre alla strutturazione della catena, hanno dato origine all’evoluzione geologica testimoniata dalla successione “superfici sommitali”s. di colle argentiera s.di m.paletta. lo schema porterebbe anche a ritenere che l’inizio dell’attività delle faglie che delimitano verso ovest le dorsali di m.tolagna e di m.prefoglio-m.scalette (o quanto meno l’inizio della fase più importante delle dislocazioni lungo di esse) sia riferibile all’intervallo compreso fra il completamento della superficie di m.tito e la sedimentazione degli strati basali della successione di cesi colle curti. 77.. ccoonncclluussiioonnii l’esame critico della bibliografia geologica relativa alle superfici relitte di buona parte dell’appennino centromeridionale ha portato ad approfondire alcuni aspetti dei modelli genetici che sono alla base delle interpretazioni finora pubblicate. un primo aspetto riguarda l’unitarietà della “paleosuperficie sommitale”. partendo dalla critica al procedimento che porta a correlare le spianate sommitali solo sulla base del fatto che si tratta delle superfici relitte più antiche nell’ambito delle varie successioni terrazzate osservate e dalle numerose figura 5 – quadro schematico della diffusione areale di alcune superfici relitte. legenda: a piano di colfiorito; b piano di monte lago; 1 superficie di m.fema (“gruppo spianate sommitali”); 2 superficie di m.tito; 3 superficie di rasenna; 4 faglie ad attività meso-supra pleistocenica. schematic outline of the distribution of some remnant surfaces. key: a piano di colfiorito; b piano di monte lago; 1 m. fema surfaces (“summit surfaces group”) ; 2 m. tito surface; 3 rasenna surface; 4 – meso-supra pleistocene faults. l’interpretazione delle superfici relitte ... riserve che si possono sollevare nei riguardi delle ricostruzioni che logicamente ne conseguono (come quella che ipotizza l’estensione della paleosuperficie sommitale su tutto l’appennino), è stata prospettata la possibilità che le spianate sommitali possano essere riferibili non ad un unico evento morfogenetico, ma ad un insieme di più eventi verificatisi nell’ambito di tutta l’evoluzione geologica precedente al sollevamento. un secondo aspetto della problematica relativa alle superfici relitte riguarda l’evoluzione dei fenomeni erosivi che sono all’origine della distribuzione spaziale delle più alte delle superfici incassate in quelle sommitali. la difficoltà di ipotizzare valli di larghezza sufficiente a comprendere tutti i lembi appartenenti ad uno stesso ordine (larghezza dell’ordine anche di parecchi km), possono essere rimosse ammettendo che l’alternanza di fasi di approfondimento e di spianamento, che ha caratterizzato tutto l’approfondimento del reticolo, abbia interessato non singole larghe vallate, ma insiemi di valli minori, accumunate dal fatto di essere condizionate da livelli di base relativamente uniformi. ambedue gli schemi evolutivi proposti hanno sensibili implicazioni nei riguardi dell’interpretazione tettonica di superfici relitte. il primo induce a ritenere che l’operazione di ricavare indicazioni sull’entità dei sollevamenti differenziali dalle differenze di quota delle superfici sommitali debba essere limitata alle sole zone nelle quali si possono proporre fondate correlazioni fra le stesse superfici. il secondo, oltre a complicare il problema delle correlazioni fra i lembi relitti, riduce considerevolmente l’importanza che le quote attuali delle superfici relitte hanno nei riguardi della ricostruzione di deformazioni tettoniche. nonostante queste limitazioni, le superfici relitte possono fornire informazioni utili ai fini della ricostruzione della evoluzione geologica di zone di catena. nel caso della zona considerata in questo lavoro, integrando la riconsiderazione dei modelli genetici con precisazioni di ordine metodologico, è stata ricostruita una successione di superfici relitte, la cui distribuzione plano-altimetrica può contribuire a precisare l’evoluzione dell’area considerata. queste precisazioni riguardano sostanzialmente: l’inizio del sollevamento e del conseguente forte approfondimento del reticolo idrografico, che risulterebbe riferibile ad un pliocene inoltrato, e quindi probabilmente più recente di quanto ipotizzato da coltorti e pieruccini (2000); l’inizio dell’attività delle faglie che bordano le dorsali di m.tolagna e m.prefoglio-m.scalette che potrebbe essere riferito all’intervallo cronologico compreso fra il completamento della superficie di m.tito e l’età degli strati basali della successione cesi-colle curti; l’origine dell’altopiano di m.lago che risulterebbe connessa con una evoluzione analoga a quella dell’altopiano di colfiorito, in accordo con le similitudini fra le caratteristiche orografiche delle due aree. rriinnggrraazziiaammeennttii l’autore ringrazia c.bartolini e f.carraro per la revisione del testo e per i suggerimenti forniti. llaavvoorrii cciittaattii amato a., azzara r., chiarabba c., cimini g.b., cocco m., di bona m., margheriti l., mazza s., mele f., selvaggi g., basili a., boschi e., courboulex f., deschamps a., gaffet s., bittarelli g., chiaraluce l., piccinini d. & ripepe m. 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(1935). i terrazzi fluviali dell’emilia, giorn. geolo., serie 2a, 9bis, 43-88 marchetti g. (1974). studi geomorfologici in rapporto alla neotetonica della fascia pedecollinare piacentina. st. trent. di sc. nat. vol.51. marchetti g., perotti c. & vercesi p.l. (1979). possible significance of the paleosurfaces with reference to the geomorphological plio-quaternari evoluzion of l’interpretazione delle superfici relitte ... the piacenza appennine. proc. 15th plenary meeting og igu commission on geomorphological survey ad mapping. catania 715 sett. 1979 marinelli o. (1922). atlante dei tipi geografici. firenze igm messina p., galadini f., galli p. & sposato a. (1999). evoluzione a lungo termine e caratteristiche della tettonica attiva nell’area umbro-marchigiana colpita dalla sequenza sismica del 1997-1998 (italia centrale). in: l.peruzza (a cura di), metodi innovativi per la stima dell’hazard: applicazione all’italia centrale. cnr – gndt? messina p., galadini f., galli p. & sposato a. (2002). quaternary basin evolution and present tectonic regime in the area of the 1997-1998 umbriamarche seismic sequence (central italy). geomorphology, 42 nesci o., savelli d. & veneri f. (1992). terrazzi vallivi e superfici di spianamento nell’evoluzione del rilievo appenninico marchigiano. studi geol.camerti, vol.spec. 1992/1 penck a. (1955). morphological analysis of landoforms. london, mc millan sestini a. (1939) osservazioni geomorfologiche sull’appennino tosco-emiliano tra il reno ed il bisenzio. att. soc. tosc. scienze nat., xlviii sestini a. (1981). un’antica superficie di erosione nei monti del chianti. riv. geogr. it., 88, 214-220 82 c. bosi ms. ricevuto il 26 marzo 2002 testo definitivo ricevuto il 28 maggio 2002 ms. received: march 26, 2002 final text received: june 28, 2002 available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 34 (1), 2021, 69-74 new data on the middle pleistocene small mammal fauna from the homo bearing site of fontana ranuccio (anagni basin, central italy). fabio bona 1 , flavia strani 2,3 1 museo civico dei fossili di besano, besano, varese, italia. 2 dipartimento di scienze della terra, sapienza università di roma, roma, italia. 3 istituto italiano di paleontologia umana, roma, italia. corresponding author: fabio bona <fabgeo@libero.it> abstract: the scanty small mammals material of the middle pleistocene fontana ranuccio site is characterized by the presence of six species belonging to three order: eulipotyphla, lagomorpha, and rodentia. the small mammal fossils evidence from fontana ranuccio, instead the scarce number of specimens, indicates that the site is characterized by a warm and wooded environment with subordinate grassland. keywords: systematics, chronological remarks, environmental. 1. introduction the aim of this short note is to describe for the first time the remains of small mammals, albeit limited to a few often poorly preserved fragments, from the middle pleistocene homo bearing site of fontana ranuccio (anagni, central italy). the fontana ranuccio site is located in the anagni basin about 90 km southeast of rome (fig. 1). the locality was discovered in 1976 during quarry activities for the extraction of “pozzolana” (volcanic ash). since then, several excavation campaigns have been carried out by the italian institute of human paleontology which have allowed to unearth a large number of archaeological tools (>100), faunal remains (>25,000) and four human teeth (segre & ascenzi, 1984; ascenzi et al., 1993; segre naldini et al., 2009; rubini et al., 2014; grimaldi et al., 2020). the fossiliferous layer is located within a succession of pyroclastic deposits which has been dated around 0.4 ma (pereira et al., 2018), right after the mis 12-11 passage which marks the end of the early-middle pleistocene transition with the definitive consolidation of the glacial cycles’ periodicity change from 41 kyr to 100 kyr (the socalled “mid-brunhes event”; head & gibbard, 2015). after this event an increase in the amplitude of both glacial and interglacial periods is observed with the mis 11 representing one of the longest and warmest interglacial recorded after the early-middle pleistocene transition (weirauch et al., 2008). the fontana ranuccio rich vertebrate collection is stored at the italian institute of human palaeontology (isipu) depository (anagni, frosinone). among the large mammals, 1360 specimens have been attributed to 15 taxa: palaeoloxodon antiquus, stephanorhinus sp., equus cf. e. mosbachensis, hippopotamus amphibius, dama clactoniana, cervus elaphus eostephanoceros, praemegaceros sp., bos primigenius, sus scrofa ferus, ursus deningeri, ursus sp., panthera sp., crocuta crocuta, canis mosbachensis, macaca sylvanus and homo sp. (segre & ascenzi, 1984; ascenzi et al., 1993; rubini et al., 2014: conti et al., 2021). artiodactyla is the best-represented order (68% of faunal remains) of which 69% belong to cervids and 25% to bovids (strani et al., 2018). fig. 1 geographical position of fontana ranuccio (modified from strani et al., 2018). https://doi.org/10.26382/amq.2021.01 70 bona f., strani f. 2. materials and methods the studied material was collected during past field excavations starting from 1976 to today (tab.1). the measurements of long bones and skulls presented in this paper were taken according to von den driesch (1976). the measurements of the lower first molar of microtus (terricola) sp. were taken, using a digital micrometer parker hannifin-decadal, according to sala et al. (1994). the length of the tooth row were taken on the buccal side from the first root of the p4 to the last of the m3. the fossils were compared, where necessary, with the comparison collection of one of the authors (fb). 3. systematic the scanty small mammals material of the middle pleistocene fontana ranuccio site is characterized by the presence of six species belonging to three orders: eulipotyphla, lagomorpha and rodentia. the rodents are represented by seven specimens, only four of those are determined at least to the generic level. the eulipotyphla are represented by two remains attributed one to a talpid and the second to a hedgehog. three specimens are referred to a leporid. order rodentia bowdich, 1821 family cricetidae fischer, 1817 genus microtus schrank, 1798 microtus (terricola) sp. material: 1 left hemi-mandible with m1 and m2 (fr sd-171) (fig. 1,2). measure: tab. 2. the m1 of fr sd-171 shows a posterior loop, t1, t2 and t3 alternate, t4 and t5 are extremely confluent, forming a “pitymyoid” rhombus useful to attribute the specimen to subgenus terricola, and t6 and t7 are confluent with ac3. bsa3 and lsa4 are aligned similar in shape to the extant m. (t.) gr. multiplex-subterraneus. bra4 and lra5 are well developed. the tooth axis is rectilinear with a slight concavity to the buccal side. the tooth enamel shows a positive thickness (microtus-type) differentiation. the lingual triangles are larger than the buccal ones. the cement is present in the re-entrant angles. the current taxonomic situation of the vole of the subgenus terricola of the so-called "savii" group of central-south italy, in accordance with genetic data, sees the attestation of different species of the classic italian endemic savi’s pine vole (microtus (t.) savii) as described by toschi (1965). specifically, the species microtus (t.) brachycercus is the most typical of southern italy. microtus (t.) brachycercus was primarily defined at the genetic level and secondarily for some morphological characteristics defined as a member of the “mediterranean” group; in fact, it is probably related, for the morphometric analysis of m1, to species like microtus (t.) duodecimcostatus and microtus (t.) lusitanicus of the iberian peninsula (contoli et al., 2008). according to data on extant savi’s pine vole group, which underline the great level of variation in the italian peninsula, is not possible with only one specimen to attribute fr sd-171 to a specific level. family gliridae muirhead in brewster, 1819 genus eliomys wagner, 1840 eliomys sp. material: 1 second left hemi-mandible (fr sd-172) without teeth. measure: length of the tooth row p4-m3: 6 mm. according to the shape of the radical surface (niethammer & krapp, 1978), reflecting the presence of the roots of the fourth premolar and of the three molars, and to the dimensions (fig. 2, 3) fr sd-172 is attributed to eliomys sp. the complete radical surface of fr sd-172 measured 6 mm, it is smaller than genus sciurus, that usually reached 9-11 mm (toschi, 1965) and larger for the genus dryomys, that usually reached 3-4 mm (toschi, 1965). tab. 1 commented list of the collected small mammals. tab. 2 measures of first lower molar of fr sd-171 (measures in mm). 71 genus glis brisson, 1762 cf. glis sp. material: 1 left incomplete femur (fr sd-177/1). the direct comparison of fr sd-177/1 with specimens of the comparative collection allows to tentatively attribute the fossil to cf. glis sp. order lagomorpha brandt, 1855 family leporidae fischer de waldheim, 1817 genus lepus linnaeus, 1758 lepus sp. material: 1 upper left fourth premolar or first/second molar (fr sd-173); 1 distal fragment of left humerus (fr sd-163); 1 right distal fragment of tibia (inv. 56572). measure: fr sd-173, bd (breadth of distal end): 11.8 mm; inv. 56572, bd (breadth of distal end): 14.1 mm. fr sd-173 is characterized by a not deep coronoid fossa and a wide supratrochlear hole and by a deep trochlea and small humeral capital (fig. 3a). inv. 56572, although a small fragment, presents a sub-rectangular distal articular surface and a well-developed malleulus lateralis (fig. 3b). the three lagomorph specimens, according to the dimensions (larger than the genus oryctolagus where, for example, specimens from sicily humerus bd does not reach 10 mm and tibia bd does not reach 12 mm, fig. 3ab) are attributed to lepus sp. (ascenzi et al., 1993). order eulipotyphla waddell et al., 1999 family talpidae fischer de waldheim, 1817 genus talpa linnaeus, 1758 talpa sp. material: 1 incomplete left humerus (fr 86-1). measure: fr 86-1, sd (smallest breadth of diaphysis): 4.4 mm. the morphology permit, without doubts, to attribute fr 86-1 to talpa sp. (fig. 2a-b); the large dimensions (fig. 4b) and the poorly preservation of the humerus does not permit to a clear attribution to one of the two large species of the genus talpa nowadays present in the area of fontana ranuccio: talpa europaea and talpa romana. family erinaceidae fischer de waldheim, 1817 genus erinaceus linnaeus, 1758 erinaceus sp. material: 1 proximal fragment left scapula (fr 78-3). measure: fr 78-3, glp (greatest length of the processus articularis): 10.7 mm. the fragment fr 78-3 has been determined on a comparative base to erinaceus europaeus (fig. 4a). 4. chronological considerations the association of the large mammals and the geochemical dates testified an age for fontana ranuccio site of about 400.000 (middle galerian) (pereira et al., 2018). the presence in the scanty small mammal fauna of an evolved form of microtus vole indicates that the deposit’s age is near to the early toringian (sala & masini, 2007) confirming the data for the large mammal fauna (sala & masini, 2007). 5. paleoecological inferences the small mammal fossils from fontana ranuccio, despite the scarce number of specimens (two glirids, a pine vole, a hare, a large mole and a large hedgehog), allow to make some considerations on paleoenvironmen fontana ranuccio small mammal fauna fig. 2 fontana ranuccio small mammals. 1: fr sd-171 microtus (terricola) sp., left m/1-2 (hemi-mandible); 2: fr 86-1 talpa sp., left humerus (a: dorsal, b: ventral); 3: fr sd-172 elyomys sp., left hemi-mandible. scale bars = 1mm. 72 bona f., strani f. fig. 3 fontana ranuccio lagomorphs. a, left humerus, a1: oryctolagus cuniculus, modern; a2: fr sd-163; a3: lepus europaeus, modern. b, right tibia, b1: oryctolagus cuniculus, modern; b2: inv. 56572; b3: lepus europaeus, modern. scale bars =1mm. 73 fontana ranuccio small mammal fauna fig. 4 fontana ranuccio small mammals. a left scapula, a1: erinaceus europaeus, modern; a2: fr 78-3, erinaceus sp., left scapula fragment. b left humerus, b1: talpa caeca, modern; b2: fr sd-1; b3: talpa europaea, modern. scale bars =1mm. tal conditions of the area during the deposition of fossil beds. the presence of glirids, arvicolids of the subgenus terricola and large talpids allows to interpreted as the site was characterized by the presence of warm and wooded environment with subordinate grassland and welldeveloped soils; the presence of beavers (ascenzi et al. 1993) allow to think about the presence of water stream. this is in accordance with what has been reported by palaeoecological and paleoenvironmental reconstruction based on herbivorous ungulates dietary adaptations, where most cervids (the best represented mammal group) display dental wear patterns compatible with a diet based on the consumption of soft plant resources (e.g., leaves and twigs) which are most common in wooded areas and closed canopies (strani et al., 2018). the abundance of wooded areas is also supported by results obtained by the stable isotopic analysis on e. cf. e. mosbachensis dental material, which suggests that this equid while feeding mostly on abrasive plants occupied less open habitats (e.g. at the edge between grasslands and woodlands) (strani et al., 2019). acknowledgements we thank all the palaeontologists and archaeologists that participated in the excavations and lab activities of fontana ranuccio. we are particularly grateful to luciano bruni of the italian intistute of human paleontology (isipu) for providing us endless support to our research work. we also acknowledge dr. juan manuel lópezgarcía and the anonymous reviewer for the helpful comments that allowed us to improve the manuscript. references ascenzi a., biddittu i., cassoli p.f., segre a.g., segre naldini e. 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(2014) a revision of hominin fossil teeth from fontana ranuccio (middle pleistocene, anagni, frosinone, italy). journal of human evolution, 77, 204216. sala b., masini f. (2007) late pliocene and pleistocene small mammal chronology in the italian peninsula. quaternary international, 160 (1), 4-16. sala b., masini f., torre d. (1994) villanyian arvicolids from rivoli veronese, a karst fissure in the adige valley, northeastern italy. bollettino della società paleontologica italiana, 33 (1), 3-11. segre a.g., ascenzi a. (1984) fontana ranuccio: italy's earliest middle pleistocene hominid site. current anthropology, 25 (2), 230-233. segre naldini e., muttoni g., parenti f., scardia g., segre a.g. (2009) nouvelles recherches dans le bassin plio-pléistocène d’anagni (latium méridional, italie). l’anthroplogie, 113, 66-77. strani f., demiguel d., bona f., sardella r., biddittu i., bruni l., de castro a., guadagnoli f., bellucci l. (2018) ungulate dietary adaptations and palaeoecology of the middle pleistocene site of fontana ranuccio (anagni, central italy). palaeogeography, palaeoclimatology, palaeoecology, 496, 238-247. strani f., pushkina d., bocherens h., bellucci l., sardella r., demiguel d. (2019) dietary adaptations of early and middle pleistocene equids from the anagni basin (frosinone, central italy). frontiers in ecology and evolution, 7, 176. toschi a. (1965) mammalia: lagomorpha, rodentia, carnivora, ungulata, cetacea. fauna d’italia vol. vii. calderini ed., bologna, pp. 442. von den driesch a. (1976) a guide to the measurement of animal bones from archaeological sites. cambridge press, harvard university, uk, pp. 136. weirauch d., billups k., martin p. (2008) evolution of millennial-scale climate variability during the midpleistocene. paleoceanography, 23. ms. received: november 13, 2020 revised: december 17, 2020 accepted: december 21, 2020 avaiable online: february 24, 2021 amq_28(1) coloph 3.pub available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 28 (1), 2015, iii vi aiqua congress in turin february 24th 26th, 2015 the plio-pleistocene continental record in italy: highlights on stratigraphy and neotectonics in honour of francesco carraro giuseppe orombelli university of milano-bicocca, milano, italy corresponding author: g. orombelli <giuseppe.orombelli@unimib.it> abstract: the 2015 aiqua congress (torino, february 24-26) highlighted the advances on the studies concerning the stratigraphy of plio-pleistocene continental records and the neotectonic deformation of key representative areas in both alpine and apennine contexts. two field trips that followed the conference focused on the type-area of the villafranchian succession” and on the ivrea morainic amphitheatre. keywords: quaternary, aiqua congress, torino, italy the annual aiqua (italian association for quaternary research) meeting took place in turin, february 24-26, 2015. it was organized in honour of prof. francesco carraro by the earth sciences department of the turin university, with the collaboration of colleagues from the cnr institute of geosciences and earth resources. the conference theme was "the pliocenepleistocene continental record in italy: highlights on stratigraphy and neotectonics". two topics that have marked much of the research of francesco carraro. francesco was the main promoter and one of the aiqua founders. he was aiqua president and adviser for many years. attendance at the meeting was intense and warm and showed the maturity and scientific progress achieved by the italian quaternary community. on february the 24th the historic "hall of coats of arms" (1893) of the national mountain museum "duca degli abruzzi" in monte dei cappuccini was crowded by researchers (about sixty) coming from all over italy almost as suggested by the arms of the italian cities painted on the hall walls. after the greetings of mr. roberto ferrero, on behalf of the italian alpine club and of the mountain museum, and of the department director prof. daniele castelli, the conference was opened by prof. gabriella forno, meeting organizer together with franco gianotti and giovanni monegato. during the entire day 14 communications, the visit to the posters and the presentation of two excursions to villafranca d'asti (g. forno) and to the ivrea moraine amphitheater (f. gianotti) occurred. the writer of these notes opened the communication section and, based on his blurry memories, tried to summarize the development of quaternary studies in the last half century (how much quaternary grew up! 50 years of impressive breakthrough and extraordinary adventures). thanks to the progress of research and dating methods and to the urgency of environmental problems, from specialized niche area the quaternary geology (a short term for the whole spectrum of stratigraphic, geomorphological, palaeobiological, palaeoenvironmental, palaeoclimatic and neotectonic studies dedicated to the quaternary) has fully established itself and has attracted a growing number of full-time researchers. so that, for example, from a single scientific journal in the 50s and 60s of the last century it has been reached more than 20 journals having the term quaternary (or equivalent) in the title, and even more numerous are the scientific journals that routinely publish articles of quaternary interest. then the aiqua president adele bertini took the floor (the history of late pliocene-middle pleistocene terrestrial settings in italy: vegetation and palaeoenvironmental changes as a response to the northern hemisphere insolation forcing and regional tectonics) summarizing a rich, varied and detailed contribution of palynology to the reconstruction of vegetation and environmental changes that occurred in italy from the piacenzian to the middle pleistocene, in response to cyclicalclimate change on a global scale, or to tectonic evolution at local-regional scale. r. sardella, also on behalf of russo ermolli, (pleistocene large mammals and pollen from the mercure basin southern italy) described mid-pleistocene fauna and pollen and tephrostratigraphic record contained in the fluvio-lacustrine deposits of the mercure basin (southern apennines). the presentation of mazzini (mazzini i., e. regattieri, b. giaccio, g. zanchetta, s. nomad, rn drysdale, p. galli, e. peronace the sulmona basin lake during the early last glacial: palaeoclimate vs palaeohydrology) related to the study of a carbonate lacustrine section of the sulmona basin, containing four levels of tephra dated 92 to 110 ka bp. the analysis of stable isotopes and ostracod associations helped to identify and correlate climatic events that have marked the early stages of the last main glacial cycle. m. spadi (m. spadi, m. nocentini, e. gliozzi, d. cosentino the early evolutive stages of the l’aquila basin (central italy) inferred from paleontological and stratigraphical analyses) showed the plio-pleistocene stratigraphic succession representative of the early stages of infill of the intermontane basin of l’aquila, when it was still divided into two sub-basins separated by a bedrock threshold. the environmental development, also documented with the ostracod assemblages, experienced a main phase of tectonic uplift highlighted by a stratigraphic unconformity occurring in both the two sub-basins. thanks to his expertise and knowledge that started right in aiqua at the instigation of f. carraro and c. bosi, fabrizio galadini illustrated the current state in italy of the study of active and capable faults, and of related scientific problems and regulations (the quaternary geology applied to the study of active and capable faults: the state of knowledge in italy). s. gori addressed the topic of changes of the hydrographic network (stream piracy, drainage reversal) in central apennines, caused by erosional phases related to the tectonic evolution of the chain during the earlymiddle pleistocene transition (s. gori, e. falcucci , g. scardia, s. nomad, h. guillou, f. galadini, p. fredi early capture of a central apennine (italy) internal basin as a consequence of enhanced regional uplift at the early-middle pleistocene transition). in the tiber basin (valle umbra) palaeocarpological remains and pollen data collected from the section of the beveragna-arquata quarry provided information on the late pleistocene palaeoclimate and palaeoenvironment, described by r. bizzarri (a. baldanza, r. bizzarri, r. colacicchi, p. corrado, d. magri, e. martinetto early capture of a central apennine (italy) internal basin as a consequence of enhanced regional uplift at the earlymiddle pleistocene transition). with the note presented by a. irace (a. irace, g. monegato, e. tema, e. martinetto, d. gianolla, e. vassio, l. bellino, d. violanti the first late piacenziangelasian fluvial record in northern italy: insights from the alessandria basin) we moved to northern italy: in the alessandria basin the coarse river sedimentation started at the end of piacenzian after a climate deterioration dated to 2.8 myr, also documented by carpoflora. in the late piacenzian-gelasian the basin was deformed by a ns shortening related to the north-apennine thrust front. on the basis of peculiarities of the lower cerrina valley (monferrato) and their stratigraphic and structural data, carlo giraudi (could the low cerrina valley – piedmont, nw italy be an early and middle pleistocene trough developed behind the monferrato thrust fig. 1 the audience at the aiqua meeting of turin in the "hall of coats of arms" of the national mountain museum. in the second row, fourth from right, francesco carraro iv orombelli g. front?) put forward the hypothesis that this sector, raised after the messinian, remained emerged during the pliocene, to become subsiding during early and middle pleistocene, because of the northward migration of the monferrato thrust beneath the vercelli plain. a. fontana (late quaternary alluvial megafans in northern italy), on behalf of the co-author p. mozzi too, described the megafan alluvial system, placed at the foot of the alps during the last glacial maximum (27-19 ka bp) and incised during the lateglacial-early holocene. in the veneto-friuli area distal parts of megafans are directly connected to the adriatic and have been affected by the holocene sea levelrise. p. mozzi spoke instead about the interpretation problems related to the montebelluna megafan at the mis 3-2 transition (p. mozzi, s. rossato, v. pascucci, s. andreucci, g. monegato, a. fontana, d. sechi aggradation of the montebelluna megafan (ne italy) at the mis 3-2 transition, problems and perspectives.) m. e. poli and g. monegato showed extensive evidence of neotectonic deformations along the southern alps thrust-front in western friuli (neotectonic evidence of the plio-pleistocene activity of the eastern southalpine thrust front in western friuli). in particular they showed morphotectonic evidence of faults that displace alluvial fans referred to the lgm with metric height differences, involving sliding rates up to 0.6 mm / year. e. falcucci (e. falcucci, m.e. poli, f. galadini, g. paiero, g. scardia, a. zanferrari first paleoseismological evidence of active deformation along the eastern front of the southern alps ne italy, friuli) described evidence of recent deformations induced by faults related to seismic events that occurred in the vi-vii and in the xv-xvi centuries ad. before the lunch offered by the organization, marco giardino brilliantly and nicely sketched with spirit the figure and work of francesco carraro, quaternary geologist and disseminator of knowledge on surface environments, adding to his say with numerous photos of the celebrated professor. francesco carraro replied with a brief greeting, sincere and heartfelt, welcomed by the audience with a prolonged applause. at the end of the day, g. forno shortly illustrated the field excursion to the area of villafranca d’asti, where two deltaic and fluvial sedimentary sequences separated by an angular unconformity are attributed respectively to piacenzian and calabrian. a regional transcurrent n-s structure at the western margin of the area was also described. the displayed posters: d. barbero, a. doglione, m.g. forno, m. gattiglio the importance of stratigraphic and structural aspects in the mitigations of landslides involving slopes near aguggia (san damiano d’asti). f. finocchiaro, s. furlani, d. lenaz, g. boschian, e. zordan sedimentological and mineralogical reconstruction of a quaternary sequence in val rosandra (trieste, ne italy). g. fubelli, g. amato, m. della seta evidence of fault inactivity: a multidisciplinary approch integrating geomorphology, stratigraphy and paleontology. e. martinetto, a. irace, g. monegato, e. vassio an updated overview of the distribution of biochronologically relevant fruit and seed taxa in the pliopleistocene of italy. m.r. palombo dispersal bioevents of large mammals in sw europe during the early pleistocene: implications for biochronology and faunal dynamics. p. sassone, r. gamba, l. navone strutture recenti nord-vergenti a basso angolo in val cerrina (monferrato casalese): nuove segnalazioni. abstracts of communications and posters are published on n. 26 (2015) of miscellaneous ingv (http:// istituto.ingv.it/l-ingv/produzione-scientifica/miscellaneaingv/) allow me here a personal thought and a tribute to francesco carraro. strong and determined in his choices, francesco came across the problems of quaternary geology in the late 60s of last century, coming from that group of young geologists who worked in universities, attending to the survey of the geological map of italy, thanks to the law 15.01.1960 ("completion and updating of the geological map of italy"), , which brought within fifteen years to survey and publication of 276 new sheets at 1:100,000 scale and the related notes. in particular carraro took a part in the survey of the sheets biella (43), peschiera del garda (48), verona (49), carmagnola (68), dronero (78-79), demonte (90), in many of which large areas are occupied by quaternary continental glacigenic or fluvial deposits. heir of the teachings of sergio venzo and roberto malaroda with his colleague and inseparable friend franco petrucci, in the following years he devoted himself to the survey of the ivrea and tagliamento morainic amphitheaters. studies of the last one, that were carried out after the friuli 1976 earthquake, brought him to further reflection on modality of the construction of the moraine systems left behind by pleistocene piedmont glaciers at the foothills of the alps. all his subsequent work was dedicated with admirable perseverance and conviction to the study of "geology of surficial formations " (his definition) with all its aspects, from stratigraphy to the geological survey, from neotectonics, to relationship with geomorphology and applied geology. francesco had a decisive role, gener v the plio-pleistocene continental record in italy ... fig. 2 the aiqua president , adele bertini, during the turin meeting ous and disinterested in promoting quaternay studies in italy, he was tireless in raising initiatives, debates, even provocation, in order to attract attention and stimulate young researchers to this field of study. his book "quaternary geology", which aimed to collect and systematize knowledge and reflections coming from its long and direct experience of study, survey and analysis was recently published. the book, which is rich in illustrations, diagrams, drawings and photographs, is a compendium of knowledge, problems, experiences that in recent decades have characterized the study of the continental quaternary in italy. it stands for new generations of researchers as an achievement on which further advances should be grounded. vi orombelli g. ms. received: may 5, 2015 final text received: may 13, 2015 imp.d'alessandro rreessppoonnssee ooff mmaaccrroobbeenntthhooss ttoo cchhaannggeess iinn ppaallaaeeooeennvviirroonnmmeennttss iinn tthhee lloowweerr--mmiiddddllee pplleeiissttoocceennee ((lluuccaanniiaa bbaassiinn,, ssoouutthheerrnn iittaallyy)) aassssuunnttaa dd’’aalleessssaannddrroo11,, rraaffaaeell llaa ppeerrnnaa && nneerrii cciiaarraannffii dipartimento di geologia e geofisica, università di bari campus universitario, via orabona 4, 70125 bari, italia 1corresponding author e-mail address: tina@geo.uniba.it abstract the lucania basin is part of the bradano trough, whose internal sectors were subject to continuous subsidence during the early pleistocene. this led to the deposition of a muddy sequence with a thickness in excess of 500 m in the montalbano jonico area (lucania). during the middle pleistocene, a general shallowing took place, starting from the more internal sectors of the lucania basin. the regressive succession exposed in the badland area of montalbano is candidate of the early/middle pleistocene boundary stratotype. the restored sequence was obtained from selected partial sections correlated by means of nine volcaniclastic layers, each of them characterised by distinct macrofauna assemblages. a gap of unknown thickness (probably a few tens of metres) divides the succession in two intervals: the lower one (a) consists of muddy deposits, the upper one (b) of muddy to sandy deposits, overlain by organogenic calcarenites in the uppermost part. integrated palaeoecologic, taphonomic and ichnologic analyses were performed in order to reconstruct bathymetric fluctuations and environmental changes, based on biotic responses. palaeocommunities from the lower interval point to background environments with moderate sedimentation rate, low hydrodynamic level and low oxygen content, punctuated by numerous events of mass deposition. palaeodepths range from the upper bathyal to the shelf break. through interval b, palaeodepths range from the shelf break to the inner shelf-nearshore. this interval includes genetically different shell beds. the inferred background environments are characterised by sedimentation rates and water-energy ranging from low to high, under fully aerobic conditions. like in the lower interval, blanketing events are numerous. within the general regressive trend, several fifthand sixth-order cyclothems are recognised throughout the sequence. vertical changes in the fossil communities within individual cycles indicate changes in water depth that parallel climatic fluctuations, as proved by climatic indicators in interval b. further, the sea-level curve proposed in the present work matches well the local oxygen isotope curve, but the bathymetric range of some of the cycles suggests a tectonic control superimposed on the climatic influence. riassunto il bacino lucano fa parte della fossa bradanica i cui settori interni furono interessati, nel corso del pleistocene inferiore, da una subsidenza pressoché continua che determinò l’accumulo di depositi prevalentemente fangosi, affioranti per uno spessore di oltre 500 m nell’area di montalbano jonico (lucania). nel pleistocene medio ebbe inizio una fase regressiva a partire dai settori più interni del bacino. la successione regressiva di montalbano è candidata come stratotipo per il limite pleistocene inferiore/medio. la sequenza è stata ricostruita sulla base di numerose sezioni parziali, correlate attraverso nove livelli guida vulcanoclastici, a loro volta caratterizzati da associazioni faunistiche diverse. un’interruzione di entità non valutabile (probabilmente di poche decine di metri) divide la successione in due intervalli: quello inferiore (intervallo a) è rappresentato da depositi fangosi, quello superiore (intervallo b) è costituito da depositi da fangosi a sabbiosi, passanti a calcareniti organogene nella parte sommitale. analisi paleocologiche, tafonomiche ed icnologiche, svolte in maniera integrata, sono state utilizzate per dedurre fluttuazioni batimetriche ed evoluzione paleoambientale. le paleocomunità dell’intervallo inferiore, permettono di dedurre ambienti di background caratterizzati da tasso di sedimentazione generalmente moderato, bassa energia e basso contenuto di ossigeno, sottoposti a numerosi eventi di deposizioni in massa e localizzati a profondità variabili fra il batiale superiore ed il margine di piattaforma. nell’intervallo b, le paleobatimetrie variano tra il margine di piattaforma e la transizione al nearshore. la presenza di shell beds di varia genesi è tipica di questo intervallo. gli ambienti di background sono caratterizzati da tasso di sedimentazione e livello di energia idrodinamica da basso ad alto e da buona ossigenazione. come nell’intervallo inferiore, sono numerosi gli eventi di blanketing. nell’ambito di una generale tendenza regressiva, sono stati riconosciuti diversi ciclotemi di quinto e sesto ordine; tale ciclicità è evidenziata dai cambiamenti, in verticale, delle associazioni fossili. il controllo climatico è confermato dalla presenza di indicatori climatici fra le faune dell’intervallo b. esiste, inoltre, un buon accordo fra i cicli dedotti sulla base del presente studio e la locale curva isotopica dell’ossigeno, anche se l’ampiezza batimetrica di alcuni cicli suggerisce la sovrapposizione di un controllo tettonico a quello climatico. keywords: benthic communities, sea level changes, oxygen changes, early-middle pleistocene, lucania basin. parole chiave: comunità bentoniche, fluttuazioni del livello marino, fluttuazioni nell’ossigenazione, pleistocene inferiore e medio, bacino lucano. il quaternario italian journal of quaternary sciences 1166(1bis), 2003, 167-182 11.. iinnttrroodduuccttiioonn the bradano trough (fig. 1) is part of a foredeep basin, extending from molise to the gulf of taranto. during the lower pleistocene a high sedimentation rate and an almost continuous downlift led to the deposition of thick clastic sequences. particularly, along the apenninic margin of the lucania basin (i.e. the southernmost part of the foredeep), active subsidence caused the deposition of hemipelagic clays interfingered with muddy turbiditic deposits. a generalized shallowing phase started in the middle pleistocene resulting in a relative shallowing of the basin, testified by a shift from upper slope to shelf depositional environments. the pleistocene marine succession cropping out in the badlands area of montalbano (fig. 2) contains fossil assemblages, that clearly indicate short-term cyclic palaeobathymetric changes. as a whole, the sequence shows 168 a. d’alessandro, r. la perna & n. ciaranfi a general regressive trend, from upper slope to inner shelf deposition (ciaranfi et al, 1997). this succession is over 500 m thick and mostly silty-clayey. except for an isolated section about 15 m thick, referred to the “large” gephyrocapsa biozone, the sequence is referred to the “small” gephyrocapsa biozone and to the pseudoemiliania lacunosa biozone, providing a reference for the selection of the lower/middle pleistocene boundary stratotype (ciaranfi et al. 1997, maiorano et al., in press). the present study investigates the palaeoenvironmental evolution inferred from the fossil assemblages in order to discriminate between the cyclically modulated climatic changes, and the tectonic control. a palaeoecological analysis of the macrofauna has been combined with ichnological and taphonomic observations, with the aim of clarify changes in depth, oxygen content, and sedimentation rate. molluscs have been primarily used due to their good distribution and abundance in the studied succession; nevertheless, environmental data have been also obtained from other groups (e.g., echinoderms, decapods, bryozoans, planktonic gastropods). such an integrated approach enables a more detailed stratigraphic resolution within a framework of predictable relations between biota and sedimentation dynamics. 22.. ssttrraattiiggrraapphhyy the “argille subappennine” formation crops out in the montalbano jonico area in a monoclinal, gently sedipping structure. in spite of several mainly n-s and nesw trending faults, a continuous succession (fig. 3) was reconstructed by numerous partial sections over an area of about 2.5 km2 (ciaranfi et al., 2001, fig. 5). nine volcaniclastic beds are present (fig. 2), ranging from a few centimetres to 50 cm in thickness. they consist of pure ashes or volcaniclastic-rich sands, occasionally with pumice clasts as redeposited material. this volcanic material is referred as have been generated by an alkaline undersaturated volcanism (de rosa in ciaranfi et al., 1996). the volcaniclastic beds (v1-v9) are associated to benthic palaeocommunities pointing to different bathymetric trends, and this allows them to be used as marker beds (ciaranfi et al., 2001, fig. 7). the recognition of alternating darker and lighter intervals (3-6 m thick) all through the section and the presence of a dark, laminated horizon rich in delectopecten vitreus (gmelin) provided further tools for correlation (ciaranfi et al., 2001, figs. 5, 7). a gap of unknown thickness (probably a few tens of metres) divides the restored succession in two intervals. the lower interval (aa), about 180 m thick, consists of dark grey, massive to locally laminated mud (i.e., silty clay to clayey silt), commonly bioturbated and with dispersed macrofossils. the upper interval (bb), over 300 m thick, consists of muddy to sandy shelf deposits, generally with abundant macrofauna, and including thick shellbeds. this interval is capped by transgressive continental conglomerates. 33.. mmeetthhooddss three main approaches have been used to unravel the depositional evolution of the study sequence. fig. 1 structural map of southern italy and location of the montalbano jonico sequence. fig. 2 view of the montalbano jonico badlands with the thickest volcaniclastic layers v5 (lower arrow) and v7 (upper arrow). 169response of macrobenthos to changes ... taphonomic observations allowed to infer the main depositional patterns (i.e., background versus event depositions, sedimentation rate, etc.). palaeoichnologic analysis has been useful to infer fluctuations in the oxygen content, and palaeoecology has been mainly applied to reconstruct bathymetric changes. the main difficulty encountered during this study was the extremely time-consuming field work, due the need of recording in continuum taphonomic features, trace fossil distribution, faunal composition and distribution, as well as sedimentological features (raw field data and the list of the taxa are available from the authors on request). the outcrop surface was first cleaned from the weathered part to expose fresh mudrock over a belt 50100 cm wide throughout the succession. mudrock was then removed down to a depth of 10-30 cm and examined. most aragonitic skeletons and, to a less extent, even the calcitic ones, had been weakened by dissolution, frequently fractured by compaction or are preserved as deformed steinkerns. a number of bulk-samples (50-100 kg of sediment) has been taken for a quantitative palaeoecological analysis, although it often turned out that the benthic palaeocommunities (i.e associations) suffered more or less preservational bias. accordingly, most analyses were carried on a qualitative or semi-quantitative base. whenever possible, fossil associations were paralleled to recent mediterranean biocoenoses or to the atlantic communities. the mediterranean biocoenoses were defined (pérès & picard, 1964) qualitatively and each of them is identified by a group of characteristic species, irrespective of their abundance. this bionomic approach, successfully adopted in the mediterranean area, is the most suitable tool for the identification of biotopes (basso & corselli, 2002) and for a more precise bathymetric location of palaeocommunities. 44.. ttaapphhoonnoommyy 44..11 ddeessccrriippttiioonn iinntteerrvvaall aa. the main taphonomic feature of this interval is highly dispersed autochthonous fossils. except for larger specimens, fossils are partly decalcified and preserved as more or less flattened steinkerns, often internally lined by pyrite (pl. 1, fig. 1). pyrite linings, or pyrite steinkerns of the smaller components (pl. 1, figs. 4, 7), can occur in several unrelated taxa, e.g. molluscs, echinoids, decapods (pl. 1, fig. 10), and foraminifers (pl. 1, fig. 14). fossils, often articulated and without signs of abrasion or encrustation, lack any preferred orientation in plane view and are concordant to bedding plane in transversal view. numerous loosely packed concentrations have been regarded as intrinsic biogenic concentrations (kidwell et al., 1986) including three thin, dark, mostly laminated intervals rich in delectopecten vitreus. the mud-pecten shells, concentrated in discontinuous pavements and layers, are pristine, concordant, densely packed, commonly preserved as closed or slightly shifted valves, mostly with an internal pyrite lining, single, and rarely in butterfly position. extrinsic biogenic concentrations are recorded by several small accumulations of small angular bioclasts due to biological activity (pl. 2, fig. 13). several obrution events are inferred by completely fig. 3 reconstructed sequence of montalbano jonico. a and b are the stratigraphic intervals considered in the present work. 170 a. d’alessandro, r. la perna & n. ciaranfi 171response of macrobenthos to changes ... fig. 1 abra longicallus (scacchi). articulated, compressed and partially fragmented specimen with internal pyrite lining. interval a, scale bar 0.5 cm. fig. 2 abra nitida (müller). specimen preserved in butterfly position. interval a, scale bar 0.5 cm. fig. 3 bathyspinula excisa (philippi). articulated, compressed and partially fragmented specimen. interval a, scale bar 0.5 cm. fig 4 delicate erect bryozoan colonies with pyrite infilling. interval b, scale bar 0.5 cm. fig. 5 undetermined “small shrimp” preserved as a muddy steinkern with minor pyrite mineralization. interval a, scale bar 2 mm. fig. 6 amphiura chiajei forbes. fully articulated specimen with arms closed around the disc. interval b (top part), scale bar 2 cm. fig. 7 ebalia nux norman & milne edwards. pyritized carapace steinkern with skeletal remains in dorsal (a) and ventral (b) view. this specimen was fully articulated but appendages were lost during the bulk-sample treatment. interval a, scale bar 2 mm. fig. 8 brissopsis lyrifera (forbes). undeformed muddy steinkern. interval b, scale bar 1 cm. figs. 9, 11 brissopsis lyrifera (forbes). strongly compressed and fragmented tests with attached raised spines. minor pyritization in fig. 11. interval a, scale bars 1 cm. fig. 10 goneplax rhomboides (linnaeus). spectacularly preserved and fully pyritized specimen. note the eyestalks in the cephalic region (arrows). interval b, scale bar 0.5 cm. fig. 12 geryon sp. fully articulated specimen with pyrite infilling in the smaller appendage cavities. interval a, scale bar 1 cm. fig. 13 funiculina quadrangularis (pallas). long fragment with inner pyrite lining. interval a, scale bar 1 cm. fig. 14 discospirina italica (costa). complete test with pyritized chamber infilling. interval a, scale bar 2 mm. fig. 15 brissopsis lyrifera (forbes). detail of articulated and raised spines. interval a, scale bar 0.5 cm. articulated crustacean skeletons and by strongly flattened infaunal echinoid tests, with some diagenetic features, such as pyritization, due to decay of organic matter. another evidence of obrution events comes from obliquely embedded and deformed echinoid tests, occasionally preserved with articulated and raised spines, which are signs of escape attempts (pl, 1, figs. 9, 11, 15). erosional, reddish silt-bearing surfaces with or without dispersed shells indicate episodic rise of waterenergy. rare, poorly evident, thin lenses of dispersed to densely-packed biogenic elements occur as sedimentological concentrations, mainly consisting of hard parts of benthic organisms (e.g., small bivalves and large foraminifers, pl. 2, fig. 3), pteropods (pl. 2, fig. 1), terrestrial leaves (pl. 2, fig. 6) and posidonia oceanica (linnaeus) leaves (pl. 2, figs. 2, 5). two, 10-20 cm thick, graded beds with erosional base occur in the uppermost part of interval a. they are mud-supported, rhodolith-rich accumulations including large and abraded shell fragments of shelf origin, testifying mass deposition events. iinntteerrvvaall bb. fossils are more abundant and better preserved than in the lower interval, but are still dispersed. the hardparts of epifaunal organisms may be encrusted, moderately bioeroded and locally abraded. the degree of disarticulation is generally low to medium, except for some shell beds in the upper part of the sequence, where bivalves are highly disarticulated and exhibit a moderate degree of fragmentation. burial events by muddy plumes are numerous and well documented by the same biostratinomic signatures as in the lower interval associated with common pyrite steinkerns (e.g. minute gastropods, bryozoans, foraminifer tests) or patinas (e.g. pyrite coatings of echinoid spines, internal linings of bivalves, etc.). different genetic types of shell beds occur. some intrinsic biogenic concentrations, such as the associations of erect bryozoans-small pectinids, protula wormscelleporiform bryozoans, and neopycnodonte, record burial episodes of sessile palaeocommunities. commonly, the appearance of these concentrations is abrupt, without any evident basal erosional surface. in rare cases, the erect-bryozoan shell beds are complex, showing a thin, sharp-based layer consisting of densely packed fragments of delicate branching, mud-tolerant bryozoans, overlain by clumps of erect bryozoans. below v3 (fig. 3), the erect bryozoan-small pectinid shell beds alternate with less fossiliferous intervals containing loosely packed to dispersed ditrupa tubes or, more rarely, articulated shells of corbula (in both cases without preferred orientations). rare extrinsic biogenic concentrations, produced by scavengers or deposit-feeders, were encountered. in other cases the original concentration has been partially distorted by high-energy events (e.g. hiatella arctica (linnaeus) and aequipecten opercularis-bearing beds), resulting in mixed concentrations. bivalve remains are densely packed and concordant to bedding, both articulated (closed shells to butterfly position) and disarticulated, complete, and the pectinids are also partially encrusted. a single case of diagenetic concentration was encountered about 15 m above the v2 volcaniclastic layer. it consists of a population of isocardia, whose shells form a loosely packed pavement. this concentration resulted from compression, as indicated by the strong deformation and fragmentation of closed valves. pure sedimentologic concentrations, formed by storm-induced currents, are represented by small lenses of bioclasts, sharp-based silty layers and, upwards, by discontinuous shell pavements (fig. 4) and by few complex shell beds resulting from multiple events. these ➧ 172 a. d’alessandro, r. la perna & n. ciaranfi thick shell beds, occurring in sandy-silty intervals, mainly consist of aequipecten opercularis (linnaeus) valves which are closely-packed, highly disarticulated, convex-upward, sometimes stacked, broken and encrusted. moreover, scattered arctica islandica (linnaeus) and ophiuroid lenses occur in the coarser interval. the bivalves consist of articulated and empty valves, and the amphiura chjaiei (forbes) skeletons are preserved perfectly articulated and with arms closed around the disc (pl. 1, fig. 6). 44..22 iinntteerrpprreettaattiioonn in most cases, background and episodic processes can be clearly distinguished (discrete signatures of speyer & brett, 1991). however, in the upper interval, the taphonomic features reflect more complex interactions, mostly due to higher energy settings (on average) and to more diverse biostratinomic responses to dynamics of sedimentation. the biostratinomic signatures in the lower interval allow to infer low-energy background palaeoenvironments located well below the maximum storm wave base and characterized by low to moderate sedimentation rates, soft and, less commonly, soupy substrates. this is clear evidence of frequent mud blanketing events by deposition of muddy plumes and rarer winnowing episodes by weak bottom currents. the diagenetic features, particularly the common pyrite linings and rarer pyrite cores, suggest low dysaerobic conditions within the sediment (brett & baird, 1986), not always related to burial events. in the upper interval, the biostratinomic signatures prevail over the diagenetic ones, thus allowing a greater accuracy when inferring palaeobathymetry. lowand high-energy taphofacies the latter indicative of settings located above the maximum storm wave base alternate. deeper settings, where taphonomic signatures are less evident and distinctive, are better defined on palaeoecological grounds. the higher energy 173response of macrobenthos to changes ... fig. 1 winnowed concentration, mostly consisting of pteropod shells. the dark spots are plant remains. interval a, scale bar 2 cm. fig. 2 winnowed concentration of posidonia oceanica (linnaeus) leaves. interval a, scale bar 1 cm. fig. 3 winnowed concentration of cyclammina cancellata brady tests. interval a, scale bar 0.5 cm. fig. 4 chondrites targionii (brongniart). interval a, scale bar 1 cm. fig. 5 leaf fragment of posidonia oceanica (linnaeus). interval a, scale bar 1cm. fig. 6 quercus sp. leaf. interval a, scale bar 1 cm. figs 7, 10 cross-sections of zoophycos spreiten. interval a, scale bar 1 cm. fig. 8 teredolites isp. in a carbonized wood. interval a, scale bar 1 cm. fig. 9 chondrites patulus fischer-ooster. interval a, scale bar 1 cm. fig. 11 track-like trace. interval b, scale bar 1 cm. fig. 12 cladichnus isp. (detail of a polished surface). interval a, scale bar 0.5 cm. fig. 13 burrow filled with shell debris (extrinsic concentration). interval a, scale bar 0.5 cm. figs. 14, 15 problematica. interval a, scale bars 0.5 cm. ➧ fig. 4 – interval b (upper part). discontinuous pavements of convex-up valves of aequipecten opercularis. some of them are heavily encrusted by corallinaceans and/or serpulids (arrows). taphofacies are indicative of middle and inner shelf settings. numerous winnowing episodes led to firmer substrates suitable for the settlement of sessile fast-growing bryozoans and their epibionts, which characterise this community. in few cases, event-concentrations of mudrelated delicate bryozoans provided the firm substrate colonized by the erect bryozoans (taphonomic feedback). in the uppermost part of sequence, taphonomic features suggest inner shelf, maybe transitional to shoreface, environments. in particular, the arctica and amphiura lenses testify reworking of both dead and living benthic organisms and their catastrophic burials during transgression culminating in a marly sediment with neopycnodonte clumps. the stratigraphic distribution of taphofacies points to clear short-term bathymetric fluctuations, within a general shallowing trend. levels with abundant pyrite steinkerns within small skeletal cavities suggests episodic dysaerobic microenvironments due to rapid burial of organic material. 55.. ppaallaaeeooiicchhnnoollooggyy 55..11 ddeessccrriippttiioonn iinntteerrvvaall aa. this interval is generally bioturbated with a highly variable bioturbation index (nil to mottled). distinctive trace fossils are visible only when they contrast in colour with the host rock. where the sediment is massive, mottling is doubtful, though more than likely. distribution of ichnotaxa and bioturbation index (bi) are reported in appendix. all through interval a, a few centimetres-thick layers, highly bioturbated by chondrites intricatus (brogniart) may occur near silty surfaces with taphonomic evidence of burial events. in the lower part, some intervals up to few metres thick are characterised by dispersed and diverse ichnotaxa (2-4 bi): chondrites (pl. 2, figs. 4, 9), cladichnus (pl. 2, fig. 12) and subordinately alcyonidiopsis are dominant. in the middle part, chondrites-zoophycos intervals may alternate with massive (mottled?) beds, or with phycosiphon-bearing strata (bi 5). zoophycos (pl. 2, figs. 7, 10), which has a discontinuous stratigraphic occurrence, disappears a few metres above the v2 layer (appendix). poorly bioturbated intervals (bi 2 to 3) with small thalassinoides, planolites and undetermined track-like traces (pl. 2, fig. 11) are also present. in the upper part, the degree of bioturbation is generally lower and ichnotaxa are mostly represented by different chondrites ichnotaxa. in three cases, chondrites intricatus is markedly thin and dispersed until its disappearance, which happens in dark, laminated delectopecten vitreus-rich sediment (fig. 5). the thickest of these intervals (fig. 6) coincides with the first occurrence of gephyrocapsa sp. 3 (upper part of the interval a). iinntteerrvvaall bb. bioturbation is poorly defined, except for the volcaniclastic beds, where scolicia (bi 3-5) or thalassinoides (bi 2-3), due to the highly contrasting colour, are clearly evident. more generally, thalassinoides and planolites, sometimes associated with track-like traces, are present, although uncommonly. bioerosion is abundant in the middle-upper part of the sequence and, more generally, in the shallower settings. 55..11 iinntteerrpprreettaattiioonn ichnologic features of interval a (i.e., high abundance and diversity of chemichnia) point to general dysoxic conditions in the muddy sediment, except for the well oxygenated phycosiphon-rich massive package. an increasing oxygen content in the bottom water and/or in the pore water may be inferred by the decrease of chemichinia diversity, as well as by the increased size of traces in the middle-upper part of the sequence. zoophycos has been found in regressive tracts (inferred by the palaeoecological analysis), thus confirming its relation with raising sedimentation rates (brett, 1998). the thin layers with minute ch. intricatus that occur throughout the muddy interval, are interpreted as colonization episodes triggered by abrupt burial of organic matter. the aforementioned, laminated, delectopecten vitreus-rich sediment are an interesting case, since this situation records the exaerobic biofacies of savdra & bottjer (1987): i.e. depletion of oxygen and sealing of the mud bottom by biomats allow specialized chemosymbiotic epifauna to live in an abenthic regime (savdra, et al., 1991). the bacterial mats might have provided a suitable bottom for the epibyssate life habit of d. vitreus. this hypothesis envisages d. vitreus as a facultative chemosymbiotic organism, although no data are found in the literature on this habit. however, hickman (1984) reports a deep-water facies, characterised by mud-pectens, in laminated, organic matter-rich sediments. a second hypothesis suggests colonization by opportunistic shelled organisms during short oxic pulses (sageman et al., 1991), but the absence of any kind of infauna remains unexplained. for interval a, an oxygen curve (fig. 5) has been reconstructed, based on the vertical distribution of oxygen-related ichnoassociations. for the d. vitreus interval containing the first occurrence of gephyrocapsa sp.3, a more detailed curve (fig. 6) was constructed based also on macrobenthic organisms sensitive to oxygen conditions. the ichnologic features of interval b point to fully aerobic conditions. rare cases of moderate dysaerobic conditions are suggested by the occurrence of abundant alcyonidiopsis and small concentrations of faecal pellets, which may be related to local obrution events (blanketing). 66.. ppaallaaeeooeeccoollooggyy 66..11 ddeessccrriippttiioonn iinntteerrvvaall aa. most of the invertebrate macrofauna consists of dispersed molluscs and, subordinately, of burrowing echinoids, macroforaminifers, decapods, and octocorals. the most typical bathyal molluscs are bathyspinula excisa (philippi) (pl. 1, fig. 3), katadesmia confusa (seguenza), delectopecten vitreus, abra longicallus (scacchi) (pl. 1, fig. 1), dentalium agile sars, and entalina tetragona (brocchi), taxa also known from other coeval bathyal sequences (di geronimo & la perna, 1997, di geronimo et al., 1997). in the short basal section, these species are particularly common, but they become more and more dispersed upwards until they are replaced by a monotypic chondrites intricatus (bi 4-5) association. in the remaining part of the interval, the strictly bathyal species and their palaeocommunities exhibit a somewhat discontinuous vertical 174 a. d’alessandro, r. la perna & n. ciaranfi 175response of macrobenthos to changes ... fig. 5 interval a. palaeobathymetric curve, main palaeocommunities and oxygen curve. each palae-ocommunity is named after the most typical faunal component(s). oxygenation levels in the bottom water are according to bromley (1996, fig. 12.1): aer = aerobic, dys = dysaerobic (upper and lower), ex = exaerobic. log abbreviations: dv = delectopecten shell-beds, m = mottling, obr = obrutions (main events), t = turbidites, tl = thin muddy turbidites (main events), w = winnowing (main events). distribution, alternating with taxa characteristic of shallower slope facies such as aporrhais uttingerianus (risso) , a. serresianus (michaud), nassarius cabrierens i s (f o n t a n n e s ), kelliella abyssicola (f o r b e s ), parvicardium minimum (philippi), hyalopecten similis (laskey), and fissidentalium rectum (gmelin). d. vitreus exhibits a peculiar distribution. it is uncommon throughout interval a, but forms closely packed concentrations in three cases (see taphonomy), giving rise to a monotypic palaeocommunity preserved in laminated layers. shells mostly belong to fully grown individuals. this species belongs to a group of thin-shelled pectinids with a deep-water distribution on muddy bottoms and facultative epibyssate habits. there is a certain systematic confusion about d. vitreus (gmelin, 1791) due to the supposed existence of a distinct species, d. abyssorum (sars, 1878), which would have slightly different ecologic needs. robba (1996) kept these two species distinct, but there is no general agreement about this distinction. in the present paper, both taxa are considered as a single mud-tolerant species referred to as d. vitreus. echinoids are almost exclusively represented by brissopsis lyrifera (forbes). decapods include the bathyal species ebalia nux norman & milne edwards and the eurybathic goneplax rhomboides (linnaeus). in some thin intervals (1-2 m), a monospecific association of the macroforaminifer discospirina italica (costa) (pl. 1, fig. 14) occurs as loosely packed concentrations. bathyal octocorals are recorded by rare remains of funiculina quadrangularis (pallas) (pl. 1, fig. 13) and isidella elongata (esper), the latter being locally common. iinntteerrvvaall bb. fauna from this interval is richer and referable to several palaeocommunities of clearly different bathymetric settings. however, changes in palaeocommunity composition are mostly gradual, making any clear-cut separation of different palaeocommunities rather difficult. moreover, the biotic response to environmental changes, particularly to edaphic factors, is so marked in shelf settings, that fossil associations highly differ from each other, and it is neither possible to outline general compositional features, nor to describe each community one by one. in this paper, a few case studies 176 a. d’alessandro, r. la perna & n. ciaranfi fig. 6 interval a. oxygen curve for the delectopecten vitreus package containing the fo (arrow) of the calcareous nannofossil gephyrocapsa sp. 3 (sensu rio, 1983). the curve is based on the vertical distribution of oxygen-related trace fossils and on other faunistic and taphonomic features. 177response of macrobenthos to changes ... fig. 7 interval b. palaeobathymetric curve and main associations. each association is named after the most typical faunal component(s). log abbreviations: dv = delectopecten shell beds, m = mottling, obr = obrutions (main events), t = turbidites, w = winnowing (main events), bs = sequence boundary, ts = transgressive surface. symbols: sun = interglacial peak, snowflake= glacial peak. 178 a. d’alessandro, r. la perna & n. ciaranfi are reported to characterise the main environments, related to sea-level fluctuations and encompassing different system tracts of sequence stratigraphy. a polyspecific middle-inner shelf molluscan palaeocommunity (between v2 and v3) contains aequipecten opercularis (linnaeus), venus multilamella (lamarck), plagiocardium papillosum (poli), turritella ex gr. communis risso, t. mediterranea monterosato, trochids (commonly encrusted by bryozoans), and small rhodoliths. below v5, another similar community is represented by arctica islandica, isocardia cor (linnaeus), large cardiids, and a. opercularis. near the top of the sequence, a sharp environmental change is recorded by a middle shelf muddy bottom palaeocommunity (turritella ex gr. communis association) abruptly replaced by an inner shelf-shoreface sandy bottom palaeocommunity (a. opercularis-a. islandica association). the latter is recorded by parautochthonous elements packed in a thick shell bed with complex internal structure, overlying an irregular erosional surface. a protula-encrusting bryozoan palaeocommunity is referred to outer shelf low-stress biotopes with cohesive substrates and low sedimentation rates. upwards, near the v5 layers, the protula-bryozoan palaeocommunity evolves into a palaeocommunity characterised by large-sized hiatella arctica, a weak borer in stiff sediments. this ecological succession culminates with the neopycnodonte cochlear palaeocommunity. nassarius edwardsi (p.fischer) is an associated species which, in this upper part of the succession, replaces the deeper taxon n. cabrierensis. another case study are erect bryozoan-small pectinid palaeocommunities, dominated by adeoniform and r e t e p o r i f o r m growth forms. they alternate with opportunistic softbottom palaeocommunities characterised by ditrupa arietina (müller) or corbula gibba (olivi). 66..22 iinntteerrpprreettaattiioonn in the montalbano succession, palaeocommunities and their stratigraphic successions provide the best tool to identify cyclic sealevel changes and key surfaces of the short-time cyclothems. such changes are recorded throughout the succession. benthic palaeocommunities from interval a are clearly indicative of upper slope environments, with a maximum depth of about 500 m. only near the middle part of this interval, the fauna suggests a shelf-margin setting (fig. 5). within this bathymetric range, several cyclic fluctuations involving changes in sedimentation rate and substrate consistency, are recorded. in these deep water settings, the fluctuations are mainly recognised basing on the relative dominance or abundance of typically bathyal species vs shelf margin and deep shelf species in the associations. palaeocommunities from interval b record outerto inner-shelf palaeocommunities, except for a nassarius cabrierensis-dominated palaeocommunity, located a few metres above the volcaniclastic layer v4, which suggests a transitional-to-slope setting, as is also indicated by the presence of rare bathyal species. like in the lower interval, palaeoecological evidence indicates cyclic sea-level changes (fig. 7), by a distinct change of shelf palaeocommunities. the occurrence, in the shallower phases, of the so-called “boreal guests” arctica islandica and pseudamussium septemradiatum (müller) together with numerous hiatella arctica specimens, whose size is similar to that of the recent north atlantic ones, suggests a climatic control for these fluctuations. sea-level lowstands are recorded by the polyspecific molluscan palaeocommunities occurring in thin horizons between v2 and v3 and below v5. near the top, the lowstand is represented by an erosional surface (ts, fig. 8) capped by a thick shell-rich bed. during deepening phases, protula worms-celleporiform bryozoan palaeocommunities flourished in outer fig. 8 – interval b (top). a = silts with turritella ex gr. communis. b = simple shell bed with arctica islandica, aequipecten opercularis and t. ex gr. communis. sb = sequence boundary. ts = transgressive surface. c = complex shell bed. d = sands with a. islandica and amphiura chiajei lenses. shelf low-stress biotopes characterised by cohesive substrates and a low sedimentation rate. near the v5 layers, the ecological replacement starting with faunas indicative of inner shelf environments, culminates with the neopycnodonte cochlear palaeocommunity that indicates the maximum flooding surface. the inversion of the trend up section is pointed out by gradually shallower palaeocommunities related to higher sedimentation rates. the neopycnodonte palaeocommunity is recurrent in interval b and highlights the positions of the maximum flooding surfaces in several cyclothems. conversely, shallowing phases are highlighted by the ditrupa arietina or corbula gibba opportunistic communities that flourish in condition of high turbidity (di geronimo & robba, 1989) and high sedimentation rate and inhabit soupy-soft substrates. these conditions are common during the late highstand system tracts. the frequent intercalations within these communities of erect-bryozoan communities (that have contrasting ecological needs) can be explained by periodic winnowing that removed the soupy boundary layer and exposed firmer substrates suitable for such sessile communities of fast-growing organisms. the vertical succession of communities confirms the upwards shallowing trend. 77.. ddiissccuussssiioonn changes in the taphonomic and palaeoecological features allowed to infer a sea-level curve for the earlymiddle pleistocene (figs. 5, 7). the curve is composed of short-term fifth(100 ka) and sixth-order (40ka) cycles, as evaluated from the local oxygen isotope curve (brilli in d’alessandro et al., 2002). the ba-thymetric range of cycles is about 100 m, although in so-me cases it considerably exceeds (over 200 m) this value. throughout interval b, the climatic control is proved by the occurrence of “cool water” molluscs indicators in the shallower phases and, occasionally, by “warm water” indicators in the deeper ones, i.e. two teleosteans (girone & varola, 2001) and a serpulid (sanfilippo, in press). conversely, no palaeoclimatic indicator occurs in the lower interval. however, there is a good match between the sea level curve and the oxygen isotope curve, which at present does not cover all the sequence. the same type of control can be then supposed for the whole sequence of montalbano. however, in some intervals, the bathymetric range is too high to be exclusively ascribed to climatic effects; therefore, a tectonic control must be an additional factor. the best example occurs near the volcaniclastic layer v4, where the bathymetric range exceeds 200 m and the kind of palaeocommunities i.e., palaeocommunities dominated by attached forms preserved as loosely to closely packed concentrations versus palaeocommunities of mostly vagile elements, occurring as dispersed assemblages are indicative of a low and high sedimentation rate respectively. the high sedimentation rate events occur during abrupt deepening phases (as inferred by the palaeocommunity succession) or follow them, thus contrasting with the expected sedimentation pattern during the transgressive system tract. this can be attributed to uplift of the continental areas surrounding the foredeep basin and resulting in increased terrigenous supply. hence, the “cycle” is exalted in magnitude and broken down in tectonically controlled steps. in interval a, palaeobathymetric ranges of sea level fluctuations are less detailed due to the intrinsic features of both deep-water fauna and biotopes. anyway, in analogy of the upper interval, the largest cycles are also regarded as partially tectonic-controlled. the ichnological assemblages from the lower interval allowed to draw a curve of changes in the bottom water oxygen content (figs. 5, 6). it is worth noticing that the dysaerobic/anaerobic events occur during maximum flooding phases, as a result of the decreased oxygen supply to the bottom water during interglacial periods. the present study also allows to elucidate the palaeoecological significance of two types of associations hitherto unknown in the literature, i.e. the delectopecten vitreus and the discospirina italica communities. in the studied sequence, d. vitreus is commonly present in muddy bottom, bathyal palaeocommunities, as is known in the literature (d’alessandro & de marco, 1993; robba, 1996; di geronimo & la perna, 1997), but this species, when recorded in monotypic palaeocommunities, seems to be related to exaerobic conditions, as suggested by ichnofossil analysis. the “exaerobic model” may be thus adequate to explain the absence of all kind of infauna, including the chondritesmakers. this hypothesis would entail a facultative chemosymbiotic feeding mode for d. vitreus. discospirina italica is an unusual deep-water macroforaminifer (adams, 1973, 1976; hottinger, pers. comm., 2001), whose ecology is poorly known. monotypic associations of discospirina, in the studied sequence, have been found during the early highstands, in slope (interval a) and outer shelf/slope settings, characterising an increased sedimentation rate related to shallowing. there is an overall good match between the inferred cycles and those obtained from other palaeontological studies, although at different degree of resolution. benthic foraminifers provide a detailed reconstruction of bathymetric changes in particular for the upper interval, while the same group allows a better resolution of oxygen changes through the interval a (stefanelli, in press), giving a curve more or less equivalent to that inferred by the ichnofossils. fish otoliths are a fairly good bathymetric indicators in the deeper settings (girone, 2000). tapho-facies analysis was particularly useful in shallower environments (soldani, 2000; ciaranfi et al., 2001). the integrated palaeontological analyses applied to the montal-bano sequence support the statement by brett (1998) that fossils provide a good tool to identify key surfaces and sedimentation dynamics within sequences, while the sequence stratigraphy model provides a predictive framework to interpret probable causes of biotic changes. aacckknnoowwlleeddggmmeennttss we thank the referees b.m. cita (milano university) and f.t. fürsich (würzburg university) for improving of the manuscript and helpful comments, and a. girone (bari university) 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(in press) climatic response in the genus plagostegus philippi, 1844 from plio-pleistocene to recent mediterranean, with description of a new species (polychaeta, serpulidae). bollettino della società paleontologica italiana. savdra c.e. & bottjer d.j., 1987 the exaerobic zone, a new oxygen-deficient marine biofacies. nature, 327: p. 54-56. savdra c.e., bottjer d.j., and seilacher a., 1991 redox-related benthic events. in einsele g., ricken w., seilacher a. (eds.): cycles and events in stratigraphy springer-verlag, berlin, p. 524-541. soldani d., 2000 utilizzo e limiti di applicabilità delle tafofacies nelle analisi di bacino. tesi di dottorato, università di bari, unpublished, pp. 114. speyer s.e. & brett c.e., 1991 taphofacies controls. in: allison p.a. & briggs d.e.g. (eds.) taphonomy: releasing the data locked in the fossil record. vol. 99 of topics in geobiology, , p. 501-545. stefanelli s. (in prep.) early-middle pleistocene benthic foraminifera microhabitats as response to oxygen variations: proxy of oxygen content? 180 a. d’alessandro, r. la perna & n. ciaranfi 181response of macrobenthos to changes ... a p p e n d ix 182 a. d’alessandro, r. la perna & n. ciaranfi a p p e n d ix a p p e n d ix b io tu rb a tio n in d e x (b i) a n d d is tr ib u tio n o f ic h n o ta xa in in te rv a l a . in d ic e d i b io tu rb a zi o n e ( b i) e d is tr ib u zi o n e d e g li ic h n o ta xa n e ll’ in te rv a llo a amq 24 giraudi impaginato 04082014 available online http://amq.aiqua.it issn (print): 2279-7327, issn (online): 2279-7335 alpine and mediterranean quaternary, 27 (1), 2014, 5 28 quaternary studies as a tool to validate seismic hazard potential of tectonic structures: the case of the monferrato thrust front (vercelli plain, nw italy) carlo giraudi enea c.r. saluggia, vercelli, italy corresponding author: c. giraudi <carlo.giraudi@enea.it> abstract: this paper proposes the study of the quaternary geological evolution of the vercelli plain (piedmont, nw italy) with the aim of validating the reliability of assumptions about seismic hazard of tectonic structures based on seismotectonic data obtained from studies at regional scale. in particular, the quaternary evolution is interpreted in order to verify and date the tectonic activity of the monferrato thrust front, i.e., the westernmost arch of the buried northern apennines front. in reference to the main purpose of the work, it is observed that only some stretches of the buried front (lucedio and cavourrina fault and, very likely, the flexures of crescentino and morano po) were active between 870 and 400 ka bp. after 400 ka bp, near crescentino and trino, some structures transversal to the monferrato front were probably activated, inducing the uplift of n-s elongated areas. the uplift affected both the northern monferrato slope and the areas of the plain located south and north of the thrust front. the uplifted trino area was limited to the east by the salera line. there are no indications of structures (fault or flexure) to the west of the trino area or which form the limits of the uplifted crescentino area, although their presence could be hypothesized. the salera line is the most important identified structure; it is very likely a complex-kinematics fault that was active from the pliocene to the upper pleistocene and the holocene. it continues to the south inside the hill areas, for a length of about 20 km. therefore, the recent tectonic movements are not associated with the monferrato thrust front, as claimed by other authors, but rather with n-s structures which are transversal to the front. although elements to evaluate the seismic hazard possibly associated with these structures are not available, it is unlikely that the seismicity alone of the easternmost apennine fronts (emilia and ferrara folds) can provide useful information to assess the seismic hazard of the vercelli plain and of northern monferrato. keywords: quaternary evolution, buried tectonic structures, climatic impact, climate and tectonic interaction, river diversions, vercelli plain, monferrato hills. 1. introduction a detailed study of the quaternary evolution of the vercelli plain (northwestern italy) is used here as a tool to assess the reliability of previous assumptions based on seismic hazard which were generally based on the analysis of historical seismicity, on the evolution of the drainage network, on the presence of quaternary sediments displaced by faults, and on gps measurements. data collected and presented in this paper are interpreted in order to verify and date the tectonic activity of the buried thrust front of this sector of the apennines. as quaternary sediments of the vercelli plain bury the monferrato thrust front (i.e., the westernmost of the three major buried arches of the northern apennines; fig. 1a) the detailed geological and geomorphological study of the plain provides a reliable tool for understanding the possible activity of the front. in fact, according to several authors (e.g. costa, 2003; dela pierre et al. 2003b; galadini et al., 2012) the activity of the frontal thrust of monferrato ended in the early pleistocene while, further to the east, the emilian and ferrara fronts are still active. this is testified also by historical and instrumental seismicity, which is totally absent in the monferrato front, and increases toward the emilian folds (galli, 2005), reaching a maximum in the ferrara folds (galli et al., 2012; burrato et al., 2012a). on the other hand, the results of other seismotectonic research, conducted at the scale of the whole po valley, led to the hypothesis that the monferrato front may be seismically active, even if characterized by earthquakes with long return periods. both bonadeo et al. (2010) and michetti et al. (2012), suggest that the level of seismic activity of the monferrato front could be similar to the two other northern apennine fronts. indeed, according to michetti et al. (2012), the monferrato front might be able to generate earthquakes of mw 6. in the past, the presence of the trino isolated ridge (known as rit in the literature), lying above the buried monferrato front, had already stimulated research by the working group on the po valley quaternary (gruppo di studio del quaternario padano: gsqp, 1976) which established that the area could have been affected by middle pleistocene tectonic activity. moreover, geodetic data reported in arca & beretta (1985) provide information on some aseismic deformations that occurred along a section which crosses the se portion of the area of this study during the period between 1897 and 1957. thus, the conflicting interpretation of tectonic activity and seismic hazard, and the presence of aseismic deformations, require detailed study of the quaternary geological evolution to determine which deformations were recorded by sediments and landforms, and thus which structures are likely to be active. in this paper, the evaluation of the deformation of quaternary sediments, including those dated as the last 2-3 ka, suggests the activity of tectonic structures which only partially match those hypothesized in the literature. to assess adequately the tectonic evolution of this area, this study takes into account the interaction between sedimentary and erosive phases driven by climate and those probably influenced by tectonics, starting from the upper lower pleistocene. 2. study area the vercelli plain lies between the river dora baltea and the ivrea morainic amphitheatre to the west, the river po and the monferrato hills to the south, the river sesia to the east and the rivers elvo and cervo to the north (fig. 2a). the plain is mainly formed by plio-pleistocene sediments, but in its southern part a thin quaternary sedimentary cover lies on marine sediments. the tertiary marine sediments, outcropping in the po riverbed, are folded and heavily deformed by the activity of the northernmost monferrato thrust front (sgd’i, 1969a; dela pierre et al., 2003a). a large part of the vercelli plain is in the sesia river catchment whereas only the western and southern portions of the plain are in the catchments of the rivers dora baltea and po (fig. 2b). it should be noted than the po catchment, which includes a large area of the western alps and the northern slope of the torino and monferrato hills, before receiving the stura di monferrato stream, narrows to 1.5-2.5 km (fig. 2b). in the monferrato hills the divide of the small catchments that drain toward the po migrates abruptly towards the north and remains very close to the plain down to the confluence with the stura stream. starting from the area of gabiano, the bed of the po is always very close to the hill slope and erodes it. the narrowing of the po catchment in the southern vercelli plain and in the northern monferrato slope is an apparent anomaly compared to the westernmost areas. the po, which is the main watercourse in the study area, during the quaternary was mostly flowing south of the monferrato hills. it migrated north of the hills only after a diversion that took place during the late pleistocene (carraro, 1976; carraro et al.,1980; 1995). before the diversion, the rivers sesia and dora baltea flowed into a river, which from now on will be referred to as the dros, formed by the confluence of the rivers dora riparia, orco, stura and other smaller streams, whose basin was in the north-western part of the alps. 3. methods in this paper a detailed discussion of the topographical, geomorphological and geological elements is presented in order to assess the chronology of the tectonic phases and to verify whether the most recent tectonic activity is actually connected with the monferrato thrust front or with other structures. topographic observations are based on the trend of the contour lines reported (ajassa et al., 1990) on the elevation map of the piedmont plain (carta altimetrica dell'alta pianura giraudi c. 6 fig. 1 apennine thrust fronts buried below the quaternary sediments of the po plain, and main structures of the monferrato thrust front. 1a: general view of the apennine buried fronts. 1b: the monferrato-torino hills thrust front according to costa (2003). 1c: the monferrato thrust fronts below the quaternary sediments of the vercelli plain, according to the geological map of italy f. vercelli (1969) and enel (1985). 1d: the monferrato thrust fronts below the quaternary sediments of the vercelli plain according to (msdi = bigi et al., 1990) and (cgt = dela pierre et al., 2003a). 7 quaternary studies as a tool to validate assumptions about seismic hazard ... piemontese in italian) at the scale of 1:250,000. the data used to draw the topographical profiles are reported on the carta tecnica della regione piemonte (the official regional topographic cartography) at a scale of 1:10,000. the profiles were designed using 5 m contour lines. the geological maps presented are the result of both field surveys carried out over a long period of time, and of the interpretation of aerial photographs. the flight done in the '50s (istituto geografico militare, flight) was mainly used, as it is the most useful one for the recognition of low terrace scarps. as a matter of fact, agricultural works carried out in the second half of the past century often erased morphological features that, in turn, could be relevant for the interpretation of the evolution of the area. the lithology of the sediment forming the surface of the terraces has been observed on terrace scarps, along the banks of streams and on ephemeral exposures. field data have been integrated with stratigraphic data from boreholes. in the area west of ronsecco and nw of the rit, the stratigraphy of the sediments was surveyed along several 2.5-m-deep, and 100-m-spaced trenches, all dug for the foundation of high voltage pylons, and arranged along two different alignments, for a total length of 7-8 km. fig. 2 location of the studied area. 2a: contour map, slope of the plain, topographic anomalies and main geological structures buried below quaternary sediments. 2b: the river po catchment basin west of the confluence of the stura stream. the chronological framework was mainly based on the morphological correlation between the terraces in the vercelli plain and the glacial and glaciofluvial features of the ivrea moraine amphitheatre (gianotti et al., 2008). the age of some sediments has been constrained by previous geochemical characterization of a tephra layer (enel, 1984), by the dating of a second tephra layer with the fission track method (enel, 1984), by some radiocarbon dating (tropeano & olive, 1989; giraudi, 1998) and by the presence of archaeological artefacts from the lower palaeolithic to the bronze age (fedele, 1976; gsqp, 1976; giraudi, 1998). i have assessed the stratigraphy of the quaternary deposits through both the stratigraphy of water wells (varalda et al., 2006; arpa piemonte, 2014), and direct observation of boreholes drilled in the framework of a study for the seismotectonic characterization of areas identified as possible locations of nuclear power plants, in the years between 1976 and 1984 (enel, 1984). the enel data have already been used for the geological map of italy at a scale of 1:50,000 (dela pierre et al., 2003a) and the stratigraphies of the boreholes carried out by enel are listed and described in the geotechnical data bank of the arpa piemonte (2014). in order to infer the quaternary tectonic deformations, thickness changes of alluvial and glaciofluvial sedimentary units and different elevations of the base of sediments forming the terraces have been evaluated. indeed, the stratigraphic data show a great thickness variability of glaciofluvial and alluvial sediments forming the plain north and south of the monferrato buried thrust front. 4. geology of the vercelli plain the vercelli plain is composed, almost completely, by glaciofluvial, fluvial and aeolian quaternary sediments (sgd’i, 1969a). marine tertiary sediments outcrop on the scarps of the highest terraces and in the bed of the river po, i.e. where the river is eroding the northern slope of the monferrato hills. as already mentioned, the southernmost portion of the plain is formed by quaternary sediments, less than 15-20 m thick, lying on the tertiary bedrock deformed by folds, fault and involved by the frontal thrust. the following description of tertiary sediments and tectonic structures is based on data derived from geophysical researches and wells dug during oil exploration campaigns (pieri & groppi, 1981; cassano et al., 1986) and the seismotectonic characterization of sites suitable for a nuclear power plant (enel, 1984). lastly, data from the po river bed derive from a survey of the outcrops. 4.1. tertiary bedrock and main tectonic structures previous works on the study area have stated the bedrock of the southern vercelli plain is formed by tertiary marine sediments involved in one or more thrust fronts. tectonic interpretations (fig. 1c; 1d) reported in sgd’i (1969a), enel (1984) and in bigi et al. (1990) show that the northernmost thrust front (balzola fault) affects at depth the lower pliocene marine sediments. south of the balzola fault, one or more thrust fronts are reported by the authors. according to costa (2003), the northernmost part of the monferrato thrust front has been extruded northwards along two lateral structures (fig. 1b) located east and west of the front. borehole data (enel, 1984) aided in recognizing 8 fig. 3 position of the boreholes and the wells, tertiary and early pleistocene sediments lying below late early pleistocene to holocene deposits. 3a: boreholes and wells used for their stratigraphic data. 3b: age of the sediments sampled in the boreholes covered by glaciofluvial and fluvial deposits, and outcropping in the po river bed, main tectonic structures inferred from the borehole stratigraphy. giraudi c. the presence of marine sediments below the quaternary glaciofluvial and fluvial sediments, mainly dated from eocene to pliocene, but also to the onset of the early pleistocene, and of early pleistocene alluvial and lacustrine sediments (fig. 3a, b). in this paper the upper pliocene marine sediments reported in enel (1984) are dated at the early pleistocene of the new international geochronological scale (gibbard et al., 2010). except for some areas (oligocene, pliocene and early pleistocene marine sediments outcropping or drilled in the rit area and south of crescentino) the boundaries between the different marine formations cannot be clearly traced. it follows that in fig. 3 the sediments and their ages are shown with symbols in correspondence to the places where they have been recognized. through borehole alignments (enel, 1984) it was possible to deduce the presence of at least two faults (cavourrina and lucedio faults fig. 3a), the position of which lies within a 40-50-m-width strip matching the distance between the closest pair of boreholes. the cavourrina fault juxtaposes oligocene and pliocene marine sediments (fig. 3b). the fault bounds the northern edge of the rit and it was very likely responsible for its uplift. west of the rit, the fault plane dips to the nw. north of the rit, according to the drilling stratigraphy, the fault plane is nearly vertical. southeast of the rit, the fault reaches at least the latitude of trino (fig. 3), where two closely spaced drillings show the presence of marls, probably oligocene (in the west) and of pliocene silty sands (in the east). there are no data that can be used to infer whether the fault continues to the south, outside of the area surveyed with boreholes. the lucedio fault trends wsw-ene, being slightly convex northward. here pliocene and lower pleistocene marine sediments are faulted against lower pleistocene fluvial and lacustrine sediments, inducing the subsidence of the northern area at least after the lower pleistocene. in the alignment where the boreholes are closer, the northward dip of the fault plane cannot be less than 80°. hydrogeological studies in the area (enel 1984) have shown that, just to the north of the lucedio fault, there are springs fed by water rising from deep aquifers (fig. 3) having a chemical and isotopic composition very different from that of water of surrounding areas. the rise of deep water also occurs nw and se of the stretch of the fault indicated by an alignment of boreholes: it is therefore probable, as suggested in enel (1984), that the lucedio fault might reach the areas north-east of crescentino and of salera, south-east of tricerro. a seismic line crossing the faults north of the rit (enel, 1984) shows that both the cavourrina and lucedio faults match the thrust fronts evidenced by the sgd’i (1969a) (fig. 1). here the cavourrina fault could partly fit in with the youngest thrust front reported by bigi et al. (1990). on the other hand, ese and wsw of crescentino, where many authors placed the monferrato thrust front (sgd’i, 1969a; pieri & groppi, 1981; enel, 1984; cassano et al., 1985; dela pierre et al., 2003), at least down to the depth of about 200 m, any of the available borehole logs account for the existence of faults similar to the lucedio one. the pliocene and lower pleistocene marine sediments dip 10-15° to the nnw and are deformed by a flexure. the flexure starts just east of crescentino near the western termination of the lucedio fault. the change of the tectonic features of the thrust front east of crescentino implies the presence of a fault crossing the front (crescentino fault) which could match the nw-se lateral ramp hypothesized by costa (2003). indeed, the crescentino fault (fig. 3b) reaches the po river bed in a place where outcropping tertiary marine sediments show nw-se fault planes. in the area between pontestura and morano po, the river bed is almost completely carved in tertiary bedrock (fig. 3b): the presence of calcareous marl suggests that it belongs to the eocene terms of the “ligurian” units, the same reported by dela pierre et al. (2003a) in the po bed south of trino. in the river bed ne of pontestura, nearly vertical marl strata, running n-s, outcrop, while to the east strata dip very irregularly and are displaced by faults. undeformed nnw-sse marl outcrop in the river bed sw of morano po, that is, east of the area where the sediments are displaced by faults. also near casale monferrato, in the river bed, eocene clay and calcareous marl of the “ligurian” units outcrop, although a few dozen metres north of the river bed, pliocene marine sediments (subzone mp14 and mp15a) have been found in boreholes (violanti & sassone, 2008). the boundary between eocene and pliocene sediments is not exposed, but strongly deformed outcropping sediments suggest the presence of an unconformity or a tectonic contact. the geological structure of the casale monferrato area matches that of the castel verrua area, south of crescentino, where pliocene sediments unconformably overlie the deposits of the “complesso indifferenziato” (“ligurian” units; zappi, 1961; dela pierre et al., 2003a,b). at casale monferrato, the contact could correspond to the projection at the surface (fig. 1c) of a nwse thrust front (evidenced in enel, 1984) or of another front (fig. 1d) hypothesized in bigi et al. (1990). 4.2. geomorphology and quaternary stratigraphy of the vercelli plain the vercelli plain is quite homogeneous, especially in the north-western and central-northern areas (fig. 2a). according to all previous works (sgd’i, 1966; sgd’i, 1969a; gsqp, 1976; carraro et al., 1975; giraudi, 1998; dela pierre et al., 2003a; gianotti et al. 2008) it is mainly formed by glaciofluvial and fluvial sediments dated between the mindel glaciation and the holocene. despite the scarcity of exposures, the stratigraphy of the sediments is fairly well known thanks to boreholes drilled for water and stratigraphic surveys. the stratigraphic data enable the thickness of the quaternary sediments to be evaluated and also to differentiate the areas in which sedimentation prevailed from others where erosion and sedimentation phases occurred. based on the abundance of terraces formed by the main streams, (fig. 4) the vercelli plain can be divided 9 quaternary studies as a tool to validate assumptions about seismic hazard ... into four parts: the north-western area, formed by some terraced surfaces, is a narrow strip surrounding the hills of the se ivrea morainic amphitheatre. the centralnorthern area, extending over about two-thirds of the studied plain, forms the main surface of the plain. the southern area is formed by seven different terraces while the last well recognizable area is the belt formed by three terraces parallel to the river beds. the four older terraces (s1 to s4) are only in the southern area, while the others (s5 to s8 and t9 to t11) are more diffuse. the stratigraphy of the sediments forming the terraces will be described from the oldest to the most recent. however, some parts of the vercelli plain are formed by terraces shaped by local streams (l1-2), and will be described separately. the relationship between sediments that form terraces and moraines of the ivrea amphitheatre indicates the glaciofluvial origin of sediments and suggests the age of some terraces. the bottom of sediments forming the oldest terrace is carved into the tertiary bedrock, while the bottom of other glaciofluvial deposits cuts into older sediments and sometimes into the tertiary bedrock. as determined in the whole of the mediterranean basin by macklin et al. (2002), i have assumed that, if the phases of coarse sedimentation predominantly correspond to periods of glacial expansion, the phases of prevailing erosion mainly correspond to interstadials or interglacials. the terraces (fig. 4), due to their characteristics, can be divided into groups. one group (s1-s3) includes only the terraces that form the rit, relating to a landscape that was significantly different to the modern one. conversely, the distribution of younger terraces (s4-t11), the inclination of their surfaces, and the direction of their scarps enable the identification of their own stream. in this group of terraces a first subgroup (s4-s8) can be distinguished: this includes terraces shaped by rivers that flowed, at least in certain parts, in areas away from the current river beds. the terraces form the eastern portion of the river dora baltea glaciofluvial fan, and the area, oriented approximately w-e, between the rit and the monferrato hills. a second subgroup includes terraces (t9-t11) lying along the modern river beds. several exposures and the stratigraphy and lithology 10 giraudi c. fig. 4 the terraces of the vercelli plain. s1-s3: terraces forming the trino isolated hill (rit). s4-s8: terraces shaped by alpine rivers when their bed was far from the modern ones. t9-t11: terraces forming a belt near the modern day alpine river beds. l1-l2: terraces shaped by local streams. of sediments obtained from boreholes show that some terrace surfaces are formed by sediments of different ages. terrace s1 sediments that form terrace s1 (“a” in fig. 5) are described in sgd’i (1969a), gsqp (1976) and enel (1984) as directly overlying the oligocene marine bedrock, 8-9 m thick, and formed, at the bottom, by glaciofluvial sandy gravel. sediments are very weathered (colour 2.5-5 yr of the munsell soil color chart, mscc). the degree of weathering of sediments is also similar to that of deposits partly outcropping on a terrace scarp eroded by the dora baltea river (“a” in fig. 5), not far from the morainic front, and assumed to be formed before the mindel glaciation (sgd’i., 1969a). a layer of pedogenized loess (coloured 5yr, mscc) lays above sandy gravel, and it is covered by a younger, pedogenized loess (coloured 7.5yr, mscc). according to the sgd’i (1969a), the older loess sedimented during the mindel glaciation, while the second one is dated at the riss glaciation. another thin and discontinuous loess horizon, (pedogenized and coloured 10yr, mscc), ends the stratigraphic sequence. the s1 glaciofluvial sediments are weathered and pedogenized to the same degree as some morainic deposits in the northern ivrea amphitheatre reported by gianotti et al. (2008). according to carraro et al. (1991) the moraines with soils coloured 2.5yr (mscc) are the oldest and, according to their palaeomagnetic characteristics, can be dated to the late early pleistocene. other 11 fig. 5 geological map of the vercelli plain. legendm1-m2: moraine ridges of the serra alloformation; a-h: late early pleistocene to late upper pleistocene glaciofluvial sediments; a: late early pleistocene (mis 22-?); b: late early pleistocene to middle pleistocene (mis 22?-mis 12); c: middle pleistocene (mis 10); d: middle pleistocene (mis 8); e: late middle pleistocene (mis 6); f: late middle pleistocene or early upper pleistocene; g: early (?) and middle upper pleistocene (mis 4?); h: late upper pleistocene (mis 2); i, l, m: late holocene. l1: sediments from valdora temporary stream and other local streams (mis 4? mis 2?); l2: sediments of the local streams (mis 2?late holocene). quaternary studies as a tool to validate assumptions about seismic hazard ... moraines, early middle pleistocene in age (gianotti et al., 2008), contain soils coloured 5yr (mscc). the s1 glaciofluvial sediments, being the oldest and most weathered, could have the same age as the oldest moraines and date back to late early pleistocene. the loess dating is based mainly on the presence of prehistoric artefacts. the younger loess covers some upper palaeolithic artefacts and can be dated at the mis 2. the intermediate loess covers lower palaeolithic artefacts and includes at the top some middle palaeolithic mousterian artefacts. thus, the top of the loess may be dated to the late middle pleistocene or upper pleistocene (fedele, 1976), that is, at mis 6 mis 3. the older loess is, therefore, older than mis 6 and dated at least at mis 8. terrace s2 the terrace surface s2 is separated from that of s1 by a scarp that reaches a height of approximately 10 m. the stratigraphy of the sediments forming the terrace ( sgd’i, 1969a; gsqp, 1976; enel, 1984), is very similar to that of s1. glaciofluvial sandy gravel and very weathered sand (coloured 2.5-5yr, mscc), (“b” in fig. 5) form the main sedimentary body. the s2 sediments, assumed to be older than the mindel glaciation by sgd’i (1969a), can be correlated to the moraines having the same degree of weathering and can be dated to the late early pleistocene or the early middle pleistocene. they are covered by two loess horizons, the older and more weathered one (colour 5yr) being covered by a less weathered one (colour 7.5yr). at the top of the younger loess, middle palaeolithic mousterian artifacts have been found (fedele, 1976). we can assume, therefore, that the loess horizons correspond to those described for the s1 surface and that they are of the same age (mis 6mis 3 and mis 8). on the whole, the sediments are 15-16 m thick. terrace s3 terrace surface s3 is separated from that of s2 through a scarp that reaches a height of approximately 10 m. the stratigraphy sediments (gsqp, 1976; enel, 1984), is made by gravelly sand and sandy gravel, with interbedded sand and silty sand layers, weathered at their top and coloured 5yr (mscc). also these sediments are originally glaciofluvial, but interbedded fine sediments are colluvia that originated from the s2 terrace scarp. the glaciofluvial sediments can be correlated to moraines having the same degree of weathering and, consequently, dated to the early middle pleistocene. as on terrace s2, the pedogenized glaciofluvial sediments are capped by two loess horizons: the older one is more weathered (5yr in colour) than the younger one (7.5yr). the loess horizons can be correlated, therefore, to those lying on terraces s1 and s2. on the whole, the thickness of sediments forming the terrace s3 can be around 15-17 m. terrace s4 the terrace s4 has been observed in three places, north of the rit and north of crescentino. here the s4 surface is preserved in two small, isolated flattened heights which are surrounded by younger terraces. the first, larger one (nearly divided into two parts by a small valley with a flat bottom) lies near san grisante, while the second one is near lamporo. sediments forming the san grisante terrace (gsqp, 1976; enel, 1984), are glaciofluvial sandy gravel covered by silt and sandy silt. glaciofluvial sediments (“b” in fig. 5) are very weathered and there is a truncated palaeosoil at their top. therefore, between the end of the glaciofluvial sedimentation and the onset of the deposition of top silts, a strong pedogenetic phase occurred which was followed by an erosion. the degree of weathering of san grisante glaciofluvial sediments is similar to that of sediments forming terraces s2 and s3 and of moraines dating back, according to carraro et al. (1991) and gianotti et al. (2008), to the late early pleistocene or the early middle pleistocene. according to gsqp (1976) the soil on the top of the glaciofluvial sediments is the socalled “ferretto”, which developed during the interglacial between the mindel and the riss glaciations, that is during the mis 11. the glaciofluvial sandy gravel should therefore have been sedimented during the mis 12 or earlier. silt and sandy silt sediments, overlying the top of glaciofluvial sandy gravel, form a layer of variable thickness (from 3.6 to 6 m) and are capped by a soil coloured 10yr/7.5yr (“d” in fig. 5). silt is similar to that forming the top of the torrazza-rondissone terrace, lying w of the dora baltea river, described by gsqp (1976). silt sedimented on a flood plain or in a palustrine basin, but at its top it consists of loess-derived deposits. in the torrazza-rondissone terrace, interbedded between the silty deposits, some 0.1-0.5-m-sized polished and striated pebbles form some stone-lines. according to gsqp (1976) pebbles could have been carried there by floating ice chunks stemming from the tongue of the dora baltea glacier. the sin-glacial origin of sediments assumed by sgd’i (1969a) is therefore confirmed. in a quarry of the torrazza-rondissone terrace, interbedded in the upper silt sediments, a horizon containing volcanic glass was sampled. mineralogical characteristics of glass suggest that it originated from the m. amiata volcano (enel, 1984), which was active between 300 and 180 ka bp (bigazzi et al., 1981), that is, in a period including the mis 8 and the early mis 6. north of the rit, top sediments forming the surface are made by 4-to-6-m thick silt, very similar in its lithology and sedimentary facies to that described above and containing remnants of the tephra layer. silt covers unweathered sandy gravel (“d” in fig. 5), about 8 m thick. below the sandy gravel, a colluvium of a soil formed by very weathered silty clay coloured 2.5yr, was sampled in a borehole. it follows that the colluvium derives from the top of the pedogenized sandy gravel forming s1, and that the sandy gravel was probably sedimented during the same cold stage just before the silt. as the top of terrace s4 is higher than the s5 (dated at the mis 6; see below), it was formed in a cold stage preceding the mis 6. based on the volcanic glass chronological framework, the cold stage is, therefore, the mis 8 (280240 ka bp). the loess-derived palustrine sediments could therefore be correlated with the oldest loess, which overlies soils coloured 2.5-5yr, identified on terraces s1, s2 and s3. terrace s5 this forms the nw part of the vercelli plain and derives from the melting of remnants of different terrace surfaces that can be distinguished only near the moraine hills. the terraces consist of glaciofluvial sediments weathered by a soil coloured 7.5yr. they outcrop dis 12 giraudi c. continuously and, generally, are limited in extent, forming an apron around the moraines. in turn, the moraines lying at the nw boundary of the study area are formed by two differently preserved series of ridges (m1 and m2 in fig. 5). the presence of a series of terraces and moraine ridges shows that the evolution of the glacial front in this area was very complex. according to gianotti et al. (2008), both moraines and glaciofluvial sediments, dated to the riss glaciation in former geological maps and papers (sgd’i, 1966; 1969a; carraro et al., 1975), pertain to the “serra alloformation” dated to the late middle pleistocene, that is, the mis 6. to the south and se the different surfaces join to form a single surface (s5, fig. 4). above the contour line 170 m a.s.l. (fig. 5), surface s5 is formed mainly by sandy gravel sediments, sometimes covered by a thin silt layer, weathered by a soil coloured 7.5yr. at a lower altitude, surface s5 develops on sediments having different ages and origins. in the area ne of lamporo, glaciofluvial sandy gravel, heavily weathered (coloured 2.5-5yr) down to a depth of 10-12 m (“b” in fig. 5), is both exposed and sampled in some boreholes; this is very similar to that underlying the silt that forms the s4 surface near san grisante. the degree of weathering of sediments is similar to that of s2 and s3 terraces and of the moraines dating back to the late early pleistocene or the early middle pleistocene (carraro et al., 1991; gianotti et al., 2008). in the area ne of lamporo, pedogenesis lasted for a longer period than in the san grisante and rit area, and has continued till the present day. arduino et al. (1984), studying the relationships between the age of soils, the presence of iron oxides and the redness of soils, evidenced that the pedogenesis did not stop during cold periods. other boreholes showed that at the northern and eastern boundaries of the area with strongly weathered sandy gravel, there are sandy gravelly sediments a few metres thick, less weathered and coloured 7.5yr (“c” in fig. 5). these sediments are covered by the younger glaciofluvial sediments that were described above, dated to the mis 6. in some places surface s5 is capped by discontinuous layers of silt, 2-3 m thick, alluvial in origin, formed by the sedimentation of material derived from the erosion of soils developed on glaciofluvial deposits. the silt can be both stiff and weathered by a soil coloured 7.5yr, or less stiff, but less pedogenized (soil coloured 10yr). the latter sometimes overlaps the more weathered one. in profiles 1 and 2 (fig. 6) it can be noted that the boundaries between the different sedimentary units described above are evidenced by small changes in the slope of the plain: the places where the most weathered sediments are exposed are the flattest. terrace s6 this terrace is only in the western plain (fig. 4). a scarp 3-4 m high separates it from s5 but it becomes less clear and nearly disappears towards the se. the terrace is made by sandy gravel (“f” in fig. 5), the thickness of which is unknown, younger than the mis 6 glaciofluvial sediments forming s5. terrace s7 the surface of terrace s7, surrounding both the rit and the s4 terraces, is well represented in the area. the scarp that separates the terrace from s6 is higher to the west and becomes smaller towards the east, and the boundary between surfaces s7 and s5 is not a real scarp, but only a slight break in the slope of the plain (profiles e, f, in fig. 6). west of the lamporo area, sediments forming the terrace (“g” in fig. 5) are mainly glaciofluvial sandy gravel, while to the east, in places where the surface is less eroded by local streams, a layer of alluvial silt, 2-3 m thick, pedogenized by a soil coloured 7.5yr, covers the sandy gravel. in a few places, the top silt is capped by another layer of silt not so stiff, with a less evoluted soil coloured 10yr, which can be correlated to the younger silt layer lying on terrace s5. the sediment thickness is on the whole about 15 m. near the sw slope of the rit, below the silt that forms surface s7, sandy gravel weathered by a soil coloured 5yr has been found. these sediments are probably remnants of the sandy gravel forming also terrace s3, only eroded at the top during the shaping of terrace s7. the terrace correlates with that evidenced by gianotti et al. (2008), outside the moraine amphitheatre, on the right of the dora baltea river, and formed by glaciofluvial deposits of the piverone alloformation. the terrace sediments, therefore, can be dated to the period following the mis 6 glacial maximum (which ended about 140 ka bp) and preceding the mis 2 glacial maximum (which started about 30 ka bp), named mis 4? in this paper. surface s7 was eroded by local streams. west of the rit, these streams caused mainly the erosion of the summit silt, while north and ne of the rit, the terrace is cut by a complex network of small valleys, the bottom of which lies between 1-2 m and 7-8 m below the terrace surface. terrace s8 the scarp dividing s7 from s8 is lower towards the west and higher towards the east: it is this feature that makes it different from those that separate the terraces s5 from s6, and s6 from s7. in the plain south of the po river, terrace s8 has been observed only west of castel verrua and east of casale monferrato, but is lacking in the intermediate area. sediments forming the terrace (“h” in fig. 5) mainly consist of sandy gravel, overlain by a soil coloured 10yr. the sediment thickness, which is known only in the trino and palazzolo area, does not exceed 10 m. the terrace correlates with that evidenced by gianotti et al. (2008), outside the moraine amphitheatre, on the right of the river dora baltea, and is formed by glaciofluvial deposits of the ivrea alloformation. inside the amphitheatre sediments of the ivrea alloformation are dated to the last glacial maximum, around 21 ka bp, according to gianotti et al. (2008), or are younger, because they also lie upstream of the terminal moraines. the sediments forming s8 can be dated, therefore, to the late upper pleistocene, between 21 and 14-15 ka bp. terraces t9, t10, t11 these are the most recent terraces and form a discontinuous strip along the river beds. it should be noted that starting from the area south of fontanetto po down to trino, the strip formed by terraces t9, t10 and t11 is narrower than in the 13 quaternary studies as a tool to validate assumptions about seismic hazard ... western and eastern areas (1.2 to 2.5 km wide, against the 2.5-5 km near crescentino and 3-3.5 km east of morano po). in the plain south of the po, between verrua savoia and casale monferrato, only terrace t11 is present. alluvial sediments forming terraces t9, t10 and t11 are mainly of sandy gravel lithology (i, l, m in fig. 5). their thickness, visible only between fontanetto po and trino, does not exceed 6-8 m. in the sediments that form terrace t9 some useful dating elements have been found. in a borehole drilled near fontanetto po an iron nail contained in the sandy gravel came to light, similar to those used by romans for the ivrea harbour in the dora baltea river (f. gambari, personal communication). in a quarry south of villanova monferrato, tree trunk remnants have been exposed, dated 380-600 ad, 115-725 ad and 440-640 ad (2σ calibrated 14c age; tropeano & olive, 1989). it follows that terrace t9 should be dated to the roman and the early medieval periods. on the po banks, near palazzolo, trino and morano po, where sandy gravel forming terraces t10 and t11 lie directly on the tertiary bedrock, at the bottom of the alluvial sediments, bronze axes and swords from the bronze age have been found (janigro d’aquino,1979; fozzati & giraudi, 1983; facchin, 1997; giraudi, 1998). near the po bed, north of camino, the t11 sediments cover the remains of a medieval building and contain remnants of poles, from the middle ages (1225-1400 and 1325 -1460 ad), and trees, dated to the renaissance (1410-1620 ad) (2σ calibrated 14c age; giraudi, 1998). on the whole we can state that sediments forming the three most recent terraces date back to the last 3-4 millennia. terraces shaped by small local streams the vercelli plain has been shaped also by local streams mainly fed by water from springs sited along the “risorgive” area (de luca et al., 2005). fig. 4 shows two areas shaped in a different way by said streams. surface l1 this is the surface, lower than s5 and s7, that forms the central and northern vercelli plain, formed mainly by sandy gravel. l1 is fairly regular but in the eastern part it appears cut by small valleys with flat bottoms, 1 to 3 m deep, produced by smaller local streams. the scarp between s5 and l1, well recognizable in the nw area, becomes difficult to identify towards the se, but nw of ronsecco it is again well recognizable. in the north-western plain, l1 narrows and enters an abandoned river bed, produced by a glacial meltwater stream, which cut into the mis 6 glaciofluvial sediments. the stream that shaped the l1 surface, therefore, came from the former stream bed (fig. 4), called valdora. according to gianotti et al. (2008) the glacial meltwater stream was linked to the piverone alloformation glacial phase, doubtfully attributed to mis 4, and was therefore contemporaneous with the glaciofluvial sedimentation forming the s7 terrace. however, the surveys carried out for this paper have evidenced that the bottom of the former valdora bed, formed by sandy gravel having a homogeneous grain size and lithology, is cut across by a gently sloping scarp a few metres high. the surface l1 begins east of the scarp, therefore it is younger than the piverone alloformation. in the southern vercelli plain, surface l1 cuts surface s7, which is correlated with said alloformation, confirming that l1 was younger. the scarp, which crosses the former valdora bed, cannot have been produced by lithological discontinuities or tectonic displacements, because these would also have affected the surrounding areas formed by older sediments. it seems reasonable to believe the bottom of the former bed was partly modified by the water of a large spring, which formed near the base of the gently sloping scarp, and was active for a period following the 14 giraudi c. fig. 6 profiles along the vercelli plain. 6a: terrace map with the position of profiles; 1, 2: profiles reported on fig. 6b; a,b,c,d,e,f: position of the profiles reported in fig. 7; 6b: profiles showing the slope of the plain, the boundaries between terraces and stratigraphic units and thickness of glaciofluvial sediments lying on early pleistocene fluvial and lacustrine deposits. 15 piverone alloformation glacial maximum. surface l2 l2 represents a cluster of surfaces shaped by local streams. in fact, the different surfaces are difficult to map because the very low scarps separating them are very difficult to follow and have been partly erased by agricultural works. l2 forms also the bottoms of the small valleys cutting into fluvial terraces and l1 surfaces. the sediments forming l2 are generally silty sand, sand and sandy gravel; their thickness, that reaches 2.5 m, is known only in the trino area because some trenches some hundreds of metres in length have been made for a channel. 4.3 thickness of glaciofluvial sediments according to borehole data the stratigraphy of sediments lying well below the terrace surfaces in the area north of the lucedio and cavourrina faults and the crescentino flexure has been evidenced by boreholes that reached a maximum depth of 200 m (fig. 7). based on the borehole alignments, some geological sections have been drawn, revealing the thickness and the relationships between both the glaciofluvial sediments and the underlying older deposits, as also the presence of possible tectonic structures. three different glaciofluvial and fluvial units (fau) have been identified, mainly formed by sandy gravel overlying, through a sharp contact, thinner fluvial and lacustrine sediments or the older fau deposits. the fluvial and lacustrine sediments are dated at the lower pleistocene, and are mainly made by sand, silt and clay, with vegetation remnants and small pieces of wood interbedded with thin sandy gravel and peat layers (enel, 1984; arpa piemonte, 2014; varalda et al., 2006). the 1st fau includes units “a” and “b” which form the terraces, and overlies lower pleistocene sediments through an erosion surface and has a maximum thickness of about 70 m. the top of the 1st fau is in general eroded and covered by later sediments. when the top of the 1st fau reaches the surface (on terrace s5) or is exposed in quarries (below the silts forming terrace s4 near san grisante) sediments are heavily weathered (soils coloured 2.5yr or 5yr). as discussed above regarding terraces s4 and s5, pedogenesis occurred probably during mis 11 and the top of the glaciofluvial sediments is dated to the mis 12 or is older. based on the age and the weathering, we assume that the 1st fau can be correlated to the strongly weathered glaciofluvial sediments of the rit. however, while on the rit sediments form three different terraces and sedimentary units with a bottom gradually at lower altitudes, north of the lucedio fault the 1st fau formed during conditions of prevailing sedimentation. there are no direct data that can suggest the real age of the base of the 1st fau, but the abrupt increase in sediment grain size at the base of the 1st fau corresponds to the grain size increase that occurred, after the sedimentation of thinner early pleistocene sediments, in the po plain and around the alps. studies carried out by muttoni et al. (2007) demonstrate that at the mouths of the alpine valleys in lombardy (east of the study area), a sharp grain size change occurred during the mis 22 quaternary studies as a tool to validate assumptions about seismic hazard ... fig. 7 stratigraphic sections of the sediments forming the vercelli plain obtained from enel (1984) boreholes. (starting ca. 870 ka bp). moreover, valla et al. (2011) have reported that around 800-900 ka bp, in the french alps, erosion phases stronger than before started. the increased erosion probably produced an increase in the volume and grain size of the debris carried by rivers in the plains surrounding the alps. since the grain size increase is a general trend, and its age agrees with the chronological framework of the 1st fau, we assume that the sharp transition from fluvial -lacustrine to glaciofluvial sediments occurred during the mis 22. the sections reported in fig. 7 show that the 1st fau sediments are not in contact with the lucedio fault. however, the sediment dip changes nearing the fault. in the northernmost area, the 1st fau sediments dip towards the south and se, as one would expect for sediments produced by alpine rivers flowing from north and nw, while near the lucedio fault they dip towards the northern quadrants. the 2nd fau lies on an erosion surface carved in the 1st fau, is mainly of sandy gravel, and reaches a maximum thickness of 20 m. its top is exposed on the s5 terrace surface (“c” in fig. 5) and, as discussed above, is covered by the mis 6 glaciofluvial sediments. the 2nd fau has been identified also in a borehole made near the lucedio fault (fig. 7, section c) embedded between the 1st fau and the glaciofluvial sediments dated mis 6. interbedded within the sandy gravel of the 2nd fau, a tephra layer has been found. its age, obtained by the fission track method, is 350±100 ka bp (enel, 1984). as sediments are of glaciofluvial origin, the tephra fall could be dated to the mis 10 (ca. 380-340 ka bp) or mis 8 (ca. 280-240 ka bp). however, the stratigraphic framework and the tephra age indicate that the tephra was deposited during the mis 10, because the sediments of the 2nd fau are older than the deposits forming terrace s4, dated mis 8. as the 2nd fau is dated at mis 10, the erosion surface that separates it from the 1st fau is probably dated mis 11. the 2nd fau is very near to, or in contact with the lucedio fault plane (fig. 7, section c). however, its deposits are not faulted, but overlie an erosion surface cut into the early pleistocene lacustrine and fluvial sediments which are displaced by the fault. this implies that, during the mis 10, a river was flowing just north of the lucedio fault. the 3rd fau includes all the sediments younger than that forming the 2nd fau. the contact between its base and the older sediments occurs through an erosion surface. the older sediments forming this fau are dated to the mis 8 in terrace t4. on the whole, the stratigraphy of the sediment evidenced by boreholes shows that in the area north of the lucedio fault sedimentation prevailed, while south of the fault erosion and depositional phases alternated. the difference between the northern and southern areas, however, disappeared during the sedimentation of the 3rd fau. 4.4. summary of the stratigraphic data the combination of morphological and stratigraphic data indicates the chronology of sediments that form the vercelli plain. the deposition of the older glaciofluvial sediments forming the 1st fau, the highest terraces and part of the s5 surface (“a” and “b” in fig. 5) started during the mis 22 (ca. 870 ka bp) and ended before the mis 11 (ca. 400 ka bp). the glaciofluvial sediments of the 2nd fau, forming also part of surface s5 (“c” in fig. 5), are dated to the mis 10 (ca. 380-340 ka bp). the glaciofluvial and lacustrine sediments (“d” in fig. 5) forming terrace s4 can be dated to the mis 8 (ca. 280 -240 ka bp). the glaciofluvial sediments (“e” in fig. 5) which form a large part of surface s5 and the terraces (5a, 5b, 5c, 5d) in the area near the moraines are dated to the mis 6 (ca. 180-130 ka bp). the glaciofluvial sediments (“g” in fig. 5) that form terrace s7 could have been deposited during the mis 4 (mis 4?) but their chronological framework is definitely bracketed between the end of the mis 6 glacial maximum (ca. 140 ka bp) and the beginning of the mis 2 (ca. 30 ka bp). nearly in the same period, or later, in the northern plain, surface l1 was shaped. the last glaciofluvial sediments (“h” in fig. 5) forming terrace s8 are dated to the mis 2 (ca. 30-14 ka bp). the most recent sediments (i, l, m, in fig. 5) forming terraces t9, t10, t11 are dated to the late holocene (ca. 4 ka bp to the present). 5. considerations on the different thickness of glaciofluvial and fluvial sediments data show that in the study area the thickness of glaciofluvial and fluvial sediments, dated between 870 ka bp and the late holocene, can be quite different (fig. 8). in general the thickness is greater (reaching 70 m) north of the thrust fronts (which match the lucedio and cavourrina faults and the crescentino and morano po flexures). south of the thrust front, the thickness of the glaciofluvial and fluvial sediments is always less than 20 m. in particular, between fontanetto po and the area just east of trino, along the younger terraces, the sediment thickness is less than 10 m. because the boreholes are mainly sited in the area between trino, the rit and crescentino, the thickness of the glaciofluvial and fluvial sediments forming the south-eastern vercelli plain is less known. in order to evaluate the sediment thickness of the eastern plain, the thickness of the sediments containing phreatic groundwater reported in hydrogeological studies (regione piemonte, 2004; varalda et al., 2006) has been used. in fact, the hydrogeological studies carried out by enel (1984) indicated that the base of the phreatic groundwater matches the base of glaciofluvial sediments. glaciofluvial sediments are thickest in the plain between lamporo and the area nw of the rit (fig. 5; 7; 8) where the very weathered sediments of the 1st fau are exposed. in the area nw and w of the rit, the isopachs are nearly parallel to the lucedio fault and show that the bottom of the 1st fau forms two depressions, elongated sw-ne, divided by a small ridge. the northernmost depression (nd in fig. 8) lies near the axis of the syncline in the pliocene and pleisto 16 giraudi c. 17 cene marine sediments, and its depth increases from east to west, in a direction opposite to that of rivers. the southernmost depression (sd in fig. 8) lies near the lucedio fault and is closed to the sw. north of crescentino and near tricerro, the isopachs are transversal to the lucedio fault and crescentino flexure and assume a direction approximately n-s. in the plain east of trino, the ns isopachs are nearly parallel to the eastern branch of the cavourrina fault. lastly, starting from the area just west of morano po and as far as casale monferrato, the isopachs have a direction nearly parallel to the flexure and to the northern slope of the monferrato hills. profiles 1 and 2 in fig. 6 and a-d in fig. 9 show the variations in the sediment thickness. in the profiles ad (fig. 9) it can be observed that there are increases in sediment thickness both west and east of the area between fontanetto po and trino. moreover, west of fontanetto po, the bottom of the sediments dips to the west, therefore in a direction opposite to the slope of the plain. the westward dip of the bottom of the sediments forming the older terraces is greater than that of the most recent deposits. the base of the sediments of terrace s7 lies ca.18 m below that reached east of fontanetto po, while the base of the sediments of terrace t8 is 2 m below. 6. data on minor morphological features in the vercelli plain other secondary morphological evidence can be analyzed and taken into account, such as the change of the inclination of the terrace surfaces. some observations about small changes of the terrace surfaces, due to the presence of different sedimentary units, were reported above. in this chapter some anomalous slope inclinations observed in the southern part of the plain will be discussed. each profile in fig. 9 refers to the surface of a single terrace. profile d represents the surface of terrace s7, profile b that of s8, profile a that of terrace t9, and profile c that of surface l2. on the profiles the thickness of the sediments forming the terraces is also reported. all the profiles show anomalous slope inclination values in the area between trino and morano po (fig. 9), where the terrace surface inclination is around 0.22 % while in the area west of trino it is between 0.09 and 0.15% and east of morano po between 0.12 and 0.17%. between the two gently dipping sectors from the profiles in fig. 9 a rough value of the scarp height can be estimated. by projecting the slope measured in the western surfaces eastward to the area with the anomaly, it is possible to evaluate the difference between the eastern ground surface and the virtual elevation of the western surface. this method allows us to obtain a height difference of ≥7 m for terrace s7, of ≥6 m for s8, and of about 2 m for terraces t9 and l2. the anomaly coincides with the area where the glaciofluvial sediments thicken. it is worth noting that all the profiles show that, west of fontanetto po, even if the thickness of the sediments increases, no superficial anomaly can be observed. 7. discussion stratigraphy, facies, age and distribution of the sediments and terraces, are useful for the discussion of the geological evolution of the vercelli plain starting from the mis 22. in the first part of the chapter the impact of climatic variations will be considered, and then the stratigraphic data will be analyzed in order to obtain useful information for assessing the tectonic activity that occurred during the last 870 ka. 7.1. the impact of climatic variations and interactions between sedimentation and tectonic activity the impact of climatic variations on the evolution of the vercelli plain is clear, as the plain was formed mainly by glaciofluvial sediments, dated between mis 10 and mis 2, connected with the glacial advances and the shaping of the ivrea moraine amphitheatre. also the erosion surfaces that separate the different glaciofluvial sedimentary bodies can be ascribed mainly to the glacial retreats that took place during the interglacials. muttoni et al (2007) suggest that also the grain size increase of the sediments dated to the mis 22 was caused by climatic variations. nevertheless the evolution of the sedimentary units quaternary studies as a tool to validate assumptions about seismic hazard ... fig. 8 map of the isobaths of the base of glaciofluvial and fluvial sediments and tectonic structures active after the sedimentation of the 1st glaciofluvial and fluvial unit. 18 giraudi c. fig. 9 topographic profiles and stratigraphic outlines in the southern vercelli plain. the profiles are based on 5 m contour lines reported on the “carta tecnica regionale” at a scale of 1:10.000 in the piemonte region. the stratigraphic data are from enel (1984) boreholes and from regione piemonte (2004). 19 and the terraces indicates that the climatic impact on the plain evolution changed through time. starting from mis 10, the evolution of the plain is characterized by alternating phases of aggradation (glaciofluvial sedimentation) and erosion and pedogenesis. erosion and pedogenesis occurred between the end of one glacial phase and the start of a new one. in the mediterranean area (macklin et al., 2002), also in places very far from the glaciers, during the interstadials, the rivers incised the sediments deposited during the preceding cold stages, while on the terraces surface the soils evolved. at least the alternating phases of aggradation and erosion of the late holocene terraces were climatically driven, as evidence by giraudi (1998). therefore climatic variations have had a great impact on the evolution of the vercelli plain during the last 400 ka. for the period preceding the mis 10, that is during the sedimentation of the 1st fau, the comparison between the parts of the plain lying north and south of the lucedio fault shows data that seem to be in contrast with the hypothesis of an evolution driven mainly by the climate. the plain north of the lucedio fault is formed by sediments up to 70 m thick, without any evidence of erosion surfaces, heavily weathered at the top, which can be dated between mis 22 and mis 12. south of the fault, the sediments having a similar age have been eroded or form (on the rit) three different sedimentary bodies whose bases are cut into the tertiary bedrock at progressively lower altitudes. the entire thickness of the three sedimentary units is between 35 and 45 m. the difference in sedimentation between the areas north and south of the fault cannot be ascribed to climate variations. we believe that, to the north, no strong erosion phases occurred because subsidence prevailed, while to the south the alternating phases of limited aggradation and strong erosion could have been produced by the interaction between tectonic uplift and variations in fluvial regime driven by climate changes. michetti et al. (2012), using a boundary r-surface sequence obtained from the stratigraphic data of oil wells, evidenced that the surface (corresponding to the base of the 1st fau of this paper) is uplifted and eroded at the top of the buried thrust fronts of the northern central po plain, while in the basins lying outside the fronts, the surface lies below very thick sedimentary cover. it can be therefore assumed that the shape of the 1st fau bottom enables the subsidence rate and the distribution and geometry of tectonic structures in the study area to be assessed. studies on the tertiary and quaternary sediments forming the monferrato hills and the basin north of the monferrato thrust front (dela pierre et. al., 1995) show that phases of subsidence of the basin can be correlated to the activity of the thrust front. mariotti & doglioni (2000) state that the subsidence in the foredeeps can be ascribed to the load of thrust sheets and/or to the slab pull effect. the pleistocene subsidence of the area external to the thrust front is well known and appears to continue the pliocene trend (sgd’i, 1969a; bigi et al., 1990; dela pierre et al., 1995; irace et al., 2009). 7.2. tectonic interpretation based on stratigraphic data interpretation of the anomalous changes in thickness and in altitude of the bottom of the 1st fau and younger sediments makes it possible to evaluate the tectonic activity and the deformation rate of some areas of the plain. elements showing tectonic deformations connected with the monferrato thrust front, but also with structures crossing it are discussed below. 7.2.1. tectonic deformations connected with the monferrato thrust front the thickness variations, the dip and the difference in the sedimentation of the 1st fau are reported in fig. 7 and fig. 8. as evidenced above, apart from the rit, the 1st fau was not found south of the lucedio fault and in the tricerro area, probably because it was eroded. the thrust front, forming the boundary between the two geologically different areas, therefore played a role in the 1st fau deformation. the 1st fau is formed by glaciofluvial sediments of rivers flowing from the northern and western quadrants, but its bottom dips in different directions. in the northernmost area the 1st fau dips gently to the south. the dip appears regular because the dora baltea river flowed from the n and nw. near the lucedio fault, the 1st fau changes its slope, dipping toward the northern quadrants and assuming a direction contrary to the river flow. the change of the inclination can be ascribed to tectonic deformations. the area where sediments dipping to the north join those dipping to the south (sections of fig. 7) is the place where sediments reach their maximum thickness. in the subsidence area w and nw of the rit, the bottom of 1st fau sediments (fig. 8) shows the presence of two depressions (nd and sd) divided by a ridge (ir). the three features have a sw-ne direction nearly parallel to the lucedio fault. the northernmost depression (nd) matches the axis of the syncline deforming also the base of the pliocene marine sediments. the nd bottom cannot have been shaped only by rivers, having also been deformed by tectonic activity. in fact, the base of the 1st fau dips to the wsw, in a direction opposite to the river flow. for the same reason the bottom of the sd depression, closed to the west, cannot have been shaped only by a river. above the ir ridge the thickness of the sediments is 15-20 m less that in the nd and sd depressions. the change of the thickness could be explained by a different degree of subsidence. the deformations of the 1st fau bottom fit the hypothesis of the presence of tectonic features (probably poorly developed folds) parallel to the lucedio fault, which can therefore be linked to the activity of the monferrato thrust front. the sediments of the 1st fau do not cross the lucedio and cavourrina faults, and so it is difficult to demonstrate when the deformation ended. but if the subsidence implies thrust front activity, then the end of quaternary studies as a tool to validate assumptions about seismic hazard ... the subsidence could imply the end of the tectonic compression. the end of the subsidence north of the lucedio fault is shown by the heavily weathered top of the sediments of the 1st fau that are exposed near the axis of the subsiding area. in fact, if the subsidence had continued, the (now) weathered sediments would have been completely covered by younger ones. it follows that the subsidence ceased before the end of the 1st fau sedimentation (mis 12 ca. 400 ka bp). as far as the cavourrina fault is concerned, it can be observed that its activity ceased before ca. 280-240 ka bp, because undeformed sediments of terrace s4 seal the fault. the fault lies not far from the western, northern and eastern scarps that form the boundaries of the rit, while no isolated ridge is preserved in the longer and wider area uplifted by the lucedio fault. the presence of the rit, and the preservation of the 1st fau sediments lying on it, suggest that the cavourrina fault activity produced an uplift stronger than the lucedio fault. we cannot exclude that the cavourrina fault activity continued also after 400 ka bp. section b in fig. 7 (in a sse-nnw direction) shows that the difference in altitude of the base of the 1st fau sediments between the area where the thickness is greater (nd depression, fig. 8) and the uplifted area (rit) can be estimated as about 80-85 m. nevertheless, the real deformation should be higher because the rit is situated further down the slope than the nd depression. section e of fig. 9 (direction ca. w-e) shows the base of the 1st fau sediments between the area west of san grisante and the rit. it evidences that the base of the sediment is uplifted near san grisante, subsiding to the east and uplifting again in the proximity of the lucedio fault and of the rit. fig. 9 shows also that the uplift of the 1st fau in the san grisante area occurs in the area north of the fault. in the area between morano po and casale monferrato, the thickness of the glaciofluvial and fluvial sediments younger than the mis 22 increases towards the north and the isopachs lie parallel to the northern monferrato slope. the trend of the isopachs is similar to that of the area s and sw of crescentino. the two areas show the same geological characteristics already evidenced by the tertiary bedrock. the similarity between the two zones enables us to assume that also the isopach trend between morano po and casale monferrato was produced by a flexure that probably corresponds to a blind thrust front (fig. 1). 7.2.2. tectonic deformations crossing the monferrato thrust front the trend of the isobaths of the base of the glaciofluvial and fluvial sediments indicates that independent tectonic deformations of the monferrato front took place. in fact, in the areas n of crescentino and ne of trino, the isopachs assume an approximately n-s direction, crossing the crescentino flexure and the lucedio fault (fig. 6, profiles 1-2; fig. 8). in particular, in the crescentino area the isopachs in a n-s direction continue also well to the north of the thrust front. the uplift of the 1st fau base near san grisante, pointed out above (section e, fig. 9), seems to have been produced by n-s deformations. both the rit and terrace s4 north of crescentino lie in the northern portion of the areas affected by n-s tectonic deformations (fig. 8). the southern boundaries of the areas affected by these deformations are near castel verrua and camino, where the hills form headlands within the alluvial plain. the n-s deformations, possibly, affect the plain, both north and south of the lucedio fault and crescentino flexure, and the monferrato hills. on terrace s4, north of crescentino, the top of the 1st fau sediments, older than glaciofluvial and palustrine deposits dated to the mis 8, is strongly pedogenized, but the soil is eroded, at least in part. probably the deformation phase along the n-s structure started before the sedimentation of the palustrine deposits and favoured the erosion of the soil. the tectonic deformations along the n-s structure in the trino area seem to be dated at the mis 8. in fact, the sedimentary facies of deposits forming the terrace s4 and the thickness of the top sediments (from ca. 4 to 6 m) highlight a decrease of the river energy and the development of a wide marsh on the flood plain, which had never formed before. the changing sedimentary facies fits the hypothesis of difficult drainage to the east, most likely caused by the slow uplift of the area lying nne or ne of terrace s4. in the area south of the rit, the profiles in fig. 9 show that between fontanetto po and the trino area, to the monferrato hill slopes, the glaciofluvial and fluvial sediments are less than 10 m thick. west of fontanetto po, sediments become thicker and their base dips to the west, that is, against the river flow. also east of trino (fig. 9), in the area where the terrace surfaces show an anomalous slope inclination, sediments become thicker, and the isopachs have a n-s direction. in the area where the glaciofluvial and fluvial sediments are less than 10-20 m thick the bedrock is of tertiary marine sediments, while where the thickness exceeds 20 m the bedrock consists of lower pleistocene continental sediments. therefore in the area where the thickness of the glaciofluvial and fluvial sediments is less, the stratigraphic gap is greater due mainly to stronger erosion. the thickening of sediments to the west and east can be observed also near tricerro, north of the lucedio fault (fig. 6, profiles 1, 2). whole data suggests that an uplift occurred mainly in the area between fontanetto po and trino, but the area is elongated to the south to the monferrato hills, and to the north at least to tricerro. a tectonic structure could exist east of the uplifted area. in fact, the increase in the thickness of the glaciofluvial sediments observed east of trino, evidenced by the isobaths running ca. n-s and crossing the flow direction of rivers, cannot have been produced by rivers alone. due to the lack of borehole alignments, it is not clear if the structure is a fault or a flexure. thus, it can be assumed the presence of an undefined tectonic element (salera line), which drove the subsidence of the eastern area. based of the isopach trend, the salera line could also reach tricerro. 20 giraudi c. 21 in the salera area there is also a flow of saline water from the tertiary bedrock (enel, 1984). according to the small-scale cartography reported in irace et al. (2009), along a belt roughly corresponding to the salera line, also the isobaths of the upper pliocene base are in a direction ca. n-s and the pliocene sediment thickness increases towards the east. faults and lineaments running n-s have been observed in the monferrato hills but are not so common. according to dela pierre et al. (2003), the paucity of n-s structures in an area having many faults, anticlines and synclines with different directions could be due to their recent (pliocene and pleistocene) age. the salera line seems the northern continuation of a strongly asymmetrical syncline lying ca. n-s, at the mouth of the cerrina valley in the po plain, pointed out by sgd’i (1969a). furthermore, the hypothetical continuation southwards of the salera line would cross the po river bed in the place where marine sediments are really strongly affected by tectonic deformation. west of the salera line, the eocene marine sediments, lying below fluvial deposits or outcropping in the po river bed, reach nearly the latitude of trino, while east of the line they reach only the latitude of morano po. therefore, it is possible that the salera line produced oblique deformations or that its activity changed in the course of time. the lucedio fault ends eastward against the salera line or, alternatively, it could continue in the salera line. in other words, this latter might have played a role in the migration northwards of the thrust front and could correspond (although with a different direction) to the transcurrent or transpressive fault hypothesized by costa (2003) in the same area. nevertheless, starting at least from mis 10, the salera line seems to have produced only the subsidence of the area east of trino. to sum up, the salera line seems to be a ca. n-s fault with complex kinematics extending from tricerro to the cerrina valley in the monferrato hills. all the structures active during the last 870 ka are reported in fig. 10. 7.3. evaluation of the uplift rate as observed above, the geological and morphological features show strong differences between the uplifted area south of the lucedio-cavourrina faults and those north of these. the features are the result of climatic variations and two different phases of tectonic activity. the maximum difference between the elevation of the 1st fau base (dated ca. 870 ka bp) in the two areas is more than 80-85 m, and may be estimated as ca. 115 m (fig. 7, section b); thus, considering that the activity of the lucedio and cavourrina faults ended before 400 ka bp, the mean uplift rate of the southern area linked to thrust front activity was 0.25 mm/yr. however in each area differences can be observed in the elevation of the 1st fau base. the deformation produced by the n-s uplift area between trino and fontanetto po can be estimated using the variations in the altitude of the base of the glaciofluvial and fluvial sediments where the base dips against upstream, that is, west of fontanetto po (fig. 9). in that area, the base of the sediments dated mis 4? lies at an elevation 22 m lower than east of fontanetto po. as without tectonic deformation the inclination of the base of the sediments should be from west to east, the area between fontanetto po and trino underwent a minimum uplift of 22 m. based on the age of the sediments (an interval between 140 and 30 ka bp), the uplift rate is thus >0.16 mm/yr. if the deformation (more than 12 m) of the base of the sediments dated mis 2, ca. 30-15 ka old (fig. 9) is considered, an uplift rate >0.4 mm/yr can be calculated. the uplift rate of the sediments forming the t9 terrace, dated to the last 2-1.5 ka but whose base could be dated to 3-4 ka, can be obtained using two different data. the first is the value of the dip against upstream, and the second is the anomalous inclination of the ter quaternary studies as a tool to validate assumptions about seismic hazard ... fig. 10 active tectonic structures during the quaternary. race surface. the inclination against upstream of the sediment base, west of fontanetto po, is about 2 m (fig. 9) and therefore the uplift rate could be nearly 0.5 mm/yr. the slope inclination anomaly of the s9 surface east of trino is nearly 2 m in correspondence with the salera line, and the uplift rate of the area during the last 2 ka should therefore be nearly 1 mm/yr. however, taking into account the uncertainty of the method, such a rate should be considered the maximum possible. on the whole, over the last 140 ka, we can estimate an uplift rate between 0.16 and 0.5 mm/yr. studies carried out in the torino hills (boano et al., 2004), sited west of the vercelli plain, evaluate 1 mm/yr the uplift rate from the middle pleistocene to the present. within the uplift area between fontanetto po and trino, the southward lowering of the altitude of the base of the glaciofluvial and fluvial sediments and of the terraces surfaces suggests that the northern area is uplifted more than the southern one. 8. tectonic interpretations based on morphologic anomalies and fluvial diversions studies reported in recent papers on the tectonics of the po plain (burrato et al. 2012a; 2012b; michetti et al., 2012) have used presumed morphological anomalies and changes in the course of rivers, jointly with structural data, to evaluate the modern tectonic activity and the deformation rates that can be ascribed to structures buried below alluvial sediments. the epicentral area of the recent seismic crisis (2012) of the emilian plain (galli et al., 2012) matches one of the areas where, according to the previous hypotheses, the drainage was strongly conditioned by the buried tectonic structures. the use of the drainage variations for estimating the activity of structures buried below the alluvial sediments of the po plain, therefore, may sometimes give reliable results. the morphological anomalies, the presence of an anomalous number of terraces and the river diversions, analyzed in this paper, provide the palaeogeographic and chronological data needed in order to complete the observations on the vercelli plain presented, in a less detailed way, in some papers (gsqp, 1976; burrato et al. 2012a; 2012b; michetti et al., 2012). the areas with topographic anomalies and complex morphology lie between the axis of the syncline north of the thrust front and the monferrato hills (fig. 2; 4; 5), i.e. the area where the stratigraphic data show the presence of quaternary tectonic deformations. the presence of s8 (ca. 30-14 ka bp) south and north of the po can indicate possible clues of tectonic activity. in fact between trino and casale monferrato, s8 is not far from the po bed, while ne of casale monferrato some small remnants of the s8 terrace are 8-10 km north of the river. also south of the po the s8 terrace remnants suggest an anomaly. the terrace is preserved only west of verrua savoia and east of casale monferrato. it is likely that the lack of s8 in the intermediate area was caused by the erosion linked to the migration of the river southwards produced by the uplift of the plain north of crescentino and trino. many river diversions highlighted by the geometry and extent of terraces of the studied area can have been produced by sedimentary and erosion processes, determined by climatic variations or tectonic deformations. the dominant influence of the climate on the evolution of the plain has already been discussed and shows a strong link between sedimentation and erosion phases, and climatic changes. certainly, in the nw vercelli plain, the dora baltea river bed migrated many times during the last 870 ka, due to the change of shape and extent of the glacial fronts and of the position of the glacial meltwater streams. during the same glacial stages, glacier melting produced more than one meltwater stream fed by different glacial lobes (carraro et al., 1975; gianotti et al., 2008). some diversions of alpine rivers and of local streams that took place in the last 2 ka were, or could have been, produced by human impact (rivers cervo and sesia in the vercelli area). many river diversions, recognized in the southern vercelli plain, occurred during the same sedimentation phase and can have been produced by the change in the inclination of the river bed as a consequence of variations in the solid load transport. however most river diversions can have been produced by tectonic deformations along the structures described above. during the period between mis 22 and mis 12 (~0.87-0.4 ma), the terraces show a diversion to the nw of the river, formed by the dora baltea and the dros, which flowed south of the rit (fig. 11a). the diversion is compatible with the uplift of the area south of the monferrato thrust front, produced by the compression that induced also the deformation of the 1st fau sediments. in that period, the northern slope of the monferrato hills should have been not very far from the rit. during the period between mis 10 and mis 8 (~0.35 -0.25 ma), in the crescentino area, the river changed its course, bypassing san grisante to the north (fig. 11b). the age of the diversion is the same as the beginning of the deformation along the n-s structure. during the same period, north of the rit, a diversion eastwards of the dora baltea and the migration of the confluence with the dros river occurred (fig. 11b). the diversion may have been produced by the uplift of the area east of lamporo. despite the climatic variations that occurred between mis 8 and mis 4?, the river continued to flow north of the lucedio fault, showing that the climate did not produce river diversions. the river ran parallel to and partly overlapped the thrust front. the position of the river was determined by the presence of the glaciofluvial fan, which limited the lateral variations toward the north, and by the presence of terraces (or of the hillslopes) to the south. the morphological situation was substantially equivalent to that which currently determines the position of the po from turin to crescentino and from morano to casale monferrato. during mis 4? (~0.14-0.03 ma), a series of diversions occurred (fig. 11c). initially the river (baltea + 22 giraudi c. 23 quaternary studies as a tool to validate assumptions about seismic hazard ... fig. 11 fluvial diversions and tectonic mobility of the vercelli plain during the period between mis 22 and mis 12 (11a), between mis 10 and mis 6 (11b), during mis 4? (11c), and between mis 3 and mis 1 (11d). dros), which flowed north of the rit, migrated slightly towards the south eroding the northern slope of the ridge, then underwent diversions that made it flow to the west and south of the rit, and later to the west and south of the terrace s4 near san grisante. these diversions are compatible with the uplift along the n-s structures in the trino and crescentino area. during this period, in the area between crescentino and trino an anomalous situation began in the relationship between the position of the river and the monferrato thrust front, because the river crossed the front and began to flow behind it, showing that the activity of the thrust had ceased. during the upper pleistocene a diversion also occurred of the po towards the plain north of the monferrato hills (carraro, 1976; carraro et al., 1995), whereas, previously, the river flowed to the south. the po diversion could have occurred during mis 4?, just during the phase of continuous diversions of the river in the southern vercelli plain. during mis 2 mis 1 there was a continuous migration to the south of the po and the dora baltea rivers (fig. 11d) and a significant shift to the west of the confluence of the two rivers. the river diversions that occurred during the mis 2 mis 1 period are compatible with the uplift of the structures, with a n-s axis, of the crescentino and trino areas. the southward river migration, which produced a strong and continuous erosion of the northern hillslopes, implies that in the crescentino and trino uplifted areas, the uplift of the northernmost portion is greater than that of the southern one, confirming the interpretation based on the variations of the altitude of the fluvial sediment base. the extreme north-south reduction of the po river drainage basin in the stretch between crescentino and trino, described above (fig. 2), may be a consequence of the southward migration of rivers. in fact, by eroding the hillside they reduced the extent of the basins of the streams that drain into the po. in the area between fontanetto po and trino, terraces t9, t10, and t11 form a strip narrower that in the area upstream and downstream. this may be a consequence of the late-holocene uplift of the area, suggested by the deformation of the fluvial sediment base (fig. 9). in the casale monferrato area, after the formation of terrace s8, the po underwent a diversion to the north (fig. 11d). west of the town, the migration of the river from north to south can be explained by the greater uplift of the northern area of the trino and crescentino north-south structures; consequently it can be assumed that the northwards diversion of the river was caused by the uplift of the southern plain and/or by the subsidence of the plain north of the po. in the rive and balzola area, some small-scale morphological clues on the late holocene terraces could suggest stream diversions. the natural origin of the diversions is uncertain, but, if the diversions had been natural, it could have been linked to the subsidence of the area ne of casale monferrato. the small valleys (forming surface l2) cutting the river terraces show that during the mis 2 mis 1 period, also the local streams suffered many diversions (fig. 11d). in particular, in the area between ronsecco and tricerro, there are remnants of small valleys abandoned because the streams were diverted n and ne. the diversion may have been produced by the uplift of the northernmost part of the n-s structure. in the area between tricerro and costanzana some morphological features linked to the northward migration of the marcova stream have been observed. the diversions may have been produced by the uplift of the n-s structure, but also by the uplift of a narrow area (fig. 11d) parallel to the buried monferrato front. 9. relationship between tectonic deformations in the arca and beretta (1985) paper, the uplift rate of some places located near casale monferrato and the vercelli plain is reported. the uplift rate was obtained by means of the comparison between data from geodetic measurements carried out in 1897 and in 1957 ad. in particular, the points lying along a section from casale monferrato to vercelli, that cross the monferrato thrust front, indicate an uplift rate of 4.32 mm/yr in the area south of the front, 1.37 mm/yr at villanova monferrato, located north of the po, between the front and the syncline axis, 1.67 mm/yr at stroppiana and 0.62 mm/yr at vercelli, located north of the syncline axis. the area south of the monferrato front has an uplift rate four times greater than in the area north of it. however, the section does not allow a threedimensional interpretation and it is therefore not possible to determine whether the deformation occurred exactly on the flexure or on the front, or along other structures transversal to the front. the morphological features that suggest a possible tectonic activity in the plain near casale monferrato are dated to the upper pleistocene. no clues showing older deformations have been found. the age of the tectonic activity makes it unlikely that the uplift was produced by the monferrato thrust front. 10. summary of tectonic interpretations, considerations on seismicity and on aseismic movements in the area the stratigraphic and morphological characteristics of the vercelli plain allow us to assess the evolution during two periods, the first between 870 and ca. 400 ka bp, the second following 400 ka bp. in the older period, evolution was influenced by the subsidence of the axial area of the syncline lying north of the lucedio fault and of the crescentino and morano po flexures, while the area between the syncline and the fault and the flexures was less subsiding, and the area south of the fault and the flexures was subject to uplift. the lucedio fault was active until ca. 400 ka bp while the cavourrina fault could have been active also later, but before 280 ka bp. as discussed above, these faults constitute the thrusts front, and therefore we can conclude that the main compression in the monferrato 24 giraudi c. 25 front ended before or about 400 ka bp. during the thrust activity the salera line and the crescentino fault acted as transcurrents or transpressives, according to the costa (2003) hypothesis. because the thrust fronts are reported on maps at a scale lower than that of the maps in this paper, and there is uncertainty about their exact position (fig. 1), it is difficult to establish in detail whether the crescentino and morano flexures lie on stretches of the monferrato thrust front, but it is likely that the flexures are superficial effects produced by the blind thrust. interpretation of the data suggests that the fronts corresponding to the lucedio and cavourrina faults and to the crescentino and morano po flexures were active at least in the period between 870 and 400 ka bp. the deformation of the sediments shows that the tectonic compression acted in different ways on the various stretches of the front during the same periods. the dip of the sediments, the degree of deformation and the dip of the fault planes indicate a clear difference between the fronts corresponding to the lucedio and cavourrina faults (the farthest from the monferrato hills) and the front that produced the flexures. according to the published papers (sgd’i, 1969a; sgd’i, 1969b; pieri and groppi, 1981; cassano et al., 1985; dela pierre et al., 2003a; festa et al., 2009), excluding the area of the lucedio and cavourrina faults, the buried thrust front of the monferrato-torino hills is always near the northern hill slope. moreover, the tertiary and quaternary sediments lying outside the thrust front show an inclination and dip very similar to that observed in the crescentino flexure. it can be deduced that, although framed within the activity of the monferrato thrust front, the lucedio and cavourrina faults and the other associated tectonic structures (crescentino fault and salera line) acted in a different way. the anomalous tectonic evolution of this part of the thrust front started well before the quaternary. in fact, the balzola fault (fig. 4; 5), which is a lower pliocene thrust front lying north of the lucedio fault (sgd’i, 1969a; pieri & groppi, 1981; cassano et al., 1985; bigi et al., 1990; enel, 1994; dela pierre et al., 2003a), is nearly parallel to the younger thrust front. naturally the data on the quaternary evolution are related to a short period, compared to the length of the tectonic phase, and cannot properly explain the tectonic anomaly of this part of the monferrato thrust front. in the last 400 ka, the only possible tectonic motions affect n-s trending structures near crescentino and trino. the activity of these structures became stronger during the last 250 ka. according to the deformation of the base of the sediments dated at the last 140 ka, the uplift rate of the north-south trino structure was between 0.16 and 0.5 mm/yr and the northern part of this structure uplifted more than the southern part. the n-s deformations were not found in other places north of the collina di torino-monferrato. it follows that these deformations are anomalous, but correspond to an area of anomaly since the lower pliocene. as the lucedio and cavourrina faults are sealed by middle pleistocene sediments, the n-s deformations can hardly be connected with the thrust front activity. is not clear whether the north-south uplifted areas are included between north-south striking faults or flexures, but east of trino lies the salera line, a very important structure with a long and complex activity. the line seems to continue from tricerro to the cerrina valley, inside the monferrato hills, reaching a length of ca 20 km. we cannot completely exclude the uplift, since mis 4?, of a short, narrow area east of tricerro (fig. 11c;d) parallel, but external, to the lower pliocene monferrato thrust front. the seismic catalogues show, for the studied area, the absence of any earthquakes between 1000 to 2006 ad (rovida et al., 2011; rsni, 2014a) and the presence, during the period covered by instrumental record, of only four events of ml ≥ 2 (rsni, 2014 b) located in trino, camino and gabiano, but the depth of the epicentres of two events near trino has been assessed as more than 50 km below ground level. because the area of casale monferrato, according to the arca and beretta (1985) geodetic data, was affected between 1897 and 1957 ad by vertical movements with values greater than 4 mm / yr -1 but there were no earthquakes, one must conclude that the area is characterized by significant aseismic movements. the aseismic uplift rate of casale monferrato is at least eight time greater than the maximum rate that can be assumed for the trino area on the basis of the geological data. 11. conclusions the study of the quaternary geological evolution of the vercelli plain shows complex morphological, stratigraphic and tectonic variations. with reference to the main aim of the work, i.e. the validation of the seismotectonic interpretations and the associated seismic hazard implications made by various authors, we can observe the following. only some stretches of the buried fronts, which were reported or assumed as active by various authors (fig. 1), have influenced or induced deformation in the quaternary sedimentation and drainage. among the buried thrust-fronts which were active in the past 870 ka (i.e., lucedio and cavourrina faults), and the flexures of crescentino and morano po, only the first two produced the most appreciable deformation. the salera line, along with another possible fault (crescentino fault), may have played a key role in the northward shift of the thrust fronts of lucedio and cavourrina. over the past 400 ka the monferrato front has no longer been active, or its activity has been very low because the base of the ii fau seals it. thus, starting at about 400 ka bp, the tectonic evolution of the thrust and of the foredeep basin differed substantially from that of the fronts of the emilia and ferrara folds which are considered active and seismogenic. from mis 10 or before, the crescentino and trino structures, transversal to the monferrato front contributed to the uplift of areas elongated approximately in a ns direction. the uplift affected both the northern quaternary studies as a tool to validate assumptions about seismic hazard ... monferrato slope and areas in the plain south and north of the thrust front. the uplifted trino area was limited to the east by the salera line. there are no indications of structures (faults or flexures) located to the west of the trino area or forming the limits of the uplifted crescentino area, although their presence might be assumed. it is possible that the aseismic uplift, geodetically recorded in the area of casale monferrato, is connected with a structure similar to those of trino and crescentino. it is possible that there is a structure that produces the uplift of a small area to the east of tricerro. the structure would lie outside of the oldest monferrato front, but its trend is sub-parallel to this. it is possible that the southern vercelli plain was affected by tectonic deformation even in the late holocene. for the period between mis 4? and the present, the maximum uplift rate of the structure of trino is evaluated as between 0.16 and 0.5 mm/yr. the most important identified structure, that was active also during the upper pleistocene and the holocene, is the salera line, an unknown structure with a complex kinematics, which might continue to the south, inside the hills, for a length of about 20 km. the presence of aseismic uplift (up to 4 mm/yr in the area of casale monferrato) in an area with very low seismicity, could justify the deformation of sediments and of terrace surfaces that occurred in the past thousands of years. however, the aseismic uplift, tested only for a few tens of years, may not be significant or may be only one aspect of the long-term tectonic evolution. in addition, as elsewhere in the world, there is the possibility that the area is subject to earthquakes with very long return periods, not reported by the seismic compilations. the detailed study of the geological evolution of the vercelli plain has therefore made it possible to characterise the tectonic structures that were active during the quaternary and to assess the uplift rate. the recent vertical movements of the surface, however, are not associable with the monferrato thrust front, as suggested previously, but to north-south unknown structures, transversal to the front, which seem to affect both the plain and the northern portion of the monferrato hills. as a concluding remark, it is unlikely that the seismicity of the easternmost apennine fronts (emilia and ferrara folds) can provide useful information to assess the seismic hazard of the vercelli plain and of the northern monferrato. aknowledgements: 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